U.S. patent application number 15/891928 was filed with the patent office on 2019-06-06 for leakage protection circuit, method and drive device.
The applicant listed for this patent is Shanghai Bright Power Semiconductor Co., Ltd.. Invention is credited to Shungen SUN, Weijia YU.
Application Number | 20190170336 15/891928 |
Document ID | / |
Family ID | 61590410 |
Filed Date | 2019-06-06 |
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United States Patent
Application |
20190170336 |
Kind Code |
A1 |
SUN; Shungen ; et
al. |
June 6, 2019 |
LEAKAGE PROTECTION CIRCUIT, METHOD AND DRIVE DEVICE
Abstract
The present disclosure provides a leakage protection circuit, a
method and a drive device. The leakage protection circuit is used
for being electrically connected with the power supply line of a
load, and may be configured to sample the power supply line at
intervals, detect the voltage of the sampled electrical signals to
determine whether the voltage of the AC input power is divided, and
provide leakage protection based on the determined result. The
present disclosure can prevent human from electric shock through
sampling the electric signals from the power supply line at
intervals and performing voltage detection and comparasion to
determine whether the voltage of the accessed AC input power is
divided, when the voltage of the accessed AC input power is
determined to be divided, the power supply line will be controlled
in non-conductive state.
Inventors: |
SUN; Shungen; (Shanghai,
CN) ; YU; Weijia; (Shanghai, CN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Shanghai Bright Power Semiconductor Co., Ltd. |
Shanghai |
|
CN |
|
|
Family ID: |
61590410 |
Appl. No.: |
15/891928 |
Filed: |
February 8, 2018 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H05B 45/37 20200101;
Y02B 20/30 20130101; G01R 31/52 20200101; Y02B 20/343 20130101;
G01R 31/40 20130101; F21V 25/04 20130101; F21K 9/272 20160801; G01R
31/44 20130101; Y02B 20/341 20130101; H05B 45/50 20200101 |
International
Class: |
F21V 25/04 20060101
F21V025/04; F21K 9/272 20060101 F21K009/272; H05B 33/08 20060101
H05B033/08; G01R 31/44 20060101 G01R031/44 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 1, 2017 |
CN |
201711252359.8 |
Claims
1. A leakage protection circuit, used for being electrically
connected with a power supply line of a load, the leakage
protection circuit being configured to sample a power supply line
voltage at intervals, detect the sampled power supply line voltage
to determine whether a voltage of an AC input power is divided, and
provide leakage protection based on the determined result.
2. The leakage protection circuit of claim 1, comprising: a
detection unit, connected with the power supply line, and
configured to output a sampling control signal based on the
detection of the power supply line voltage; a sampling unit,
connected with the detection unit, and configured to sample an
electrical signal from the power supply line based on the received
sampling control signal; and a control unit, connected with the
sampling unit, and configured to compare the voltage of the sampled
electrical signal with a predetermined power-off protection voltage
threshold and provide leakage protection based on the compared
result.
3. The leakage protection circuit of claim 2, wherein the detection
unit comprises a limited voltage detection circuit module which is
connected with the power supply line and configured to detect the
power supply line voltage and output a first sampling control
signal when the detected power supply line voltage falls within
predetermined limited voltage range.
4. The leakage protection circuit of claim 3, wherein the detection
unit further comprises a timing circuit module which is connected
with the limited voltage detection circuit module and configured to
output a second sampling control signal based on the first sampling
control signal.
5. The leakage protection circuit of claim 4, wherein the timing
circuit module is configured to set a detection timing based on the
first sampling control signal, and output the second sampling
control signal after the detection timing is exceeded.
6. The leakage protection circuit of claim 4, wherein the timing
circuit module is configured to output the second sampling control
signal within an existence duration of the first sampling control
signal.
7. The leakage protection circuit of claim 1, wherein the interval
is set based on a change period of the power supply line voltage or
based on a predetermined duration.
8. The leakage protection circuit of claim 2, wherein the control
unit comprises: a comparison circuit module, configured to compare
the voltage of the sampled electrical signal with the predetermined
power-off protection voltage threshold and output the compared
result; and a logic latch circuit module, connected with the
comparison circuit module, and configured to latch the compared
result and output a corresponding latch signal, wherein the latch
signal is representing a leakage protection control signal
generated by the leakage protection circuit.
9. The leakage protection circuit of claim 8, wherein the control
unit further comprises: a switch circuit module which is connected
with the logic latch circuit module and configured to control a
conductive state or a non-conductive state of the power supply
line.
10. The leakage protection circuit of claim 1, wherein the leakage
protection circuit is configured to stop sampling the power supply
line voltage at intervals when the power supply line is controlled
to be conductive.
11. The leakage protection circuit of claim 1, wherein the leakage
protection circuit is an LED leakage protection circuit used for
being electrically connected with the power supply line of an LED
load, and the LED leakage protection circuit is configured to
output a leakage protection control signal based on the determined
result, in order that an LED drive circuit electrically connected
with the LED leakage protection circuit gives a corresponding
leakage protection response based on the leakage protection control
signal.
12. A chip, comprising: multiple pins, wherein at least one pin of
the multiple pins is electrically connected with a power supply
line of a load; a leakage protection circuit, connected with the
pin and configured to sample a power supply line voltage at
intervals, detect the sampled power supply line voltage to
determine whether a voltage of an AC input power is divided, and
provide leakage protection based on the determined result.
13. The chip of claim 12, wherein the leakage protection circuit
comprises: a detection unit, connected with the power supply line,
and configured to output a sampling control signal based on the
detection of the power supply line voltage; a sampling unit,
connected with the detection unit, and configured to sample an
electrical signal from the power supply line based on the received
sampling control signal; and a control unit, connected with the
sampling unit, and configured to compare the voltage of the sampled
electrical signal with a predetermined power-off protection voltage
threshold and provide leakage protection based on the compared
result.
14. The chip of claim 13, wherein the detection unit comprises a
limited voltage detection circuit module which is connected with
the power supply line and configured to detect the power supply
line voltage and output a first sampling control signal when the
detected power supply line voltage falls within a predetermined
limited voltage range.
15. The chip of claim 14, wherein the detection unit further
comprises a timing circuit module which is connected with the
limited voltage detection circuit module and configured to output a
second sampling control signal based on the first sampling control
signal.
16. The chip of claim 12, wherein the interval is set based on a
change period of the power supply line voltage or based on a
predetermined duration.
17. The chip of claim 13, wherein the control unit comprises: a
comparison circuit module, configured to compare the voltage of the
sampled electrical signal with the predetermined power-off
protection voltage threshold and output the compared result; and a
logic latch circuit module, connected with the comparison circuit
module, and configured to latch the compared result and output a
corresponding latch signal, wherein the latch signal is
representing a leakage protection control signal generated by the
leakage protection circuit.
18. The chip of claim 17, wherein the control unit further
comprises: a switch circuit module which is connected with the
logic latch circuit module and configured to control a conductive
state or a non-conductive state of the power supply line.
19. The chip of claim 12, wherein the leakage protection circuit is
an LED leakage protection circuit, and is electrically connected
with a power supply line of an LED load via the pin.
20. A drive device, comprising: a rectifying circuit, configured to
rectify the accessed AC and then provide to a power supply line of
a load; a leakage protection circuit, connected with the rectifying
circuit and configured to sample a power supply line voltage at
intervals, detect the sampled power supply line voltage to
determine whether a voltage of an AC input power is divided, and
provide leakage protection based on the determined result; and a
drive circuit, connected with the leakage protection circuit and
configured to supply power to the load based on the current
rectified by the rectifying circuit.
21. The drive device of claim 20, wherein the leakage protection
circuit comprises: a detection unit, connected with the power
supply line, and configured to output a sampling control signal
based on the detection of the power supply line voltage; a sampling
unit, connected with the detection unit, and configured to sample
an electrical signal from the power supply line based on the
received sampling control signal; and a control unit, connected
with the sampling unit, and configured to compare the voltage of
the sampled electrical signal with a predetermined power-off
protection voltage threshold and provide leakage protection based
on the compared result.
22. The drive device of claim 21, wherein the detection unit
comprises a limited voltage detection circuit module which is
connected with the power supply line and configured to detect the
power supply line voltage and output a first sampling control
signal when the detected voltage falls within a predetermined
limited voltage range.
23. The drive device of claim 22, wherein the detection unit
further comprises a timing circuit module which is connected with
the limited voltage detection circuit module and configured to
output a second sampling control signal based on the first sampling
control signal.
24. The drive device of claim 21, wherein the control unit
comprises: a comparison circuit module, configured to compare the
voltage of the sampled electrical signal with the predetermined
power-off protection voltage threshold and output the compared
result; and a logic latch circuit module, connected with the
comparison circuit module, and configured to latch the compared
result and output a corresponding latch signal, wherein the latch
signal is representing the leakage protection control signal
generated by the leakage protection circuit.
25. The drive device of claim 24, wherein the leakage protection
circuit is configured to output the leakage protection control
signal to the drive circuit; and the drive circuit gives a
corresponding leakage protection response based on the leakage
protection control signal.
26. The drive device of claim 25, wherein the drive circuit
comprises an enable control unit, and the enable control unit is
configured to give a corresponding leakage protection response
based on the leakage protection control signal when the leakage
protection circuit outputs the leakage protection control
signal.
27. A leakage protection method, comprising: sampling a power
supply line voltage of a load at intervals; detecting the sampled
power supply line voltage to determine whether a voltage of an AC
input power to which the power supply line is accessed is divided;
and providing leakage protection based on the determined
result.
28. The leakage protection method of claim 27, wherein the manner
of sampling the power supply line voltage of a load at intervals
comprises: performing a limited voltage detection on the power
supply line voltage; and acquiring a sampled electrical signal from
the power supply line based on a result of the limited voltage
detection.
29. The leakage protection method of claim 28, wherein the manner
of acquiring the sampled electrical signal from the power supply
line based on a result of the limited voltage detection comprises:
acquiring a sampled electrical signal from the power supply line
after a predetermined detection timing is exceeded and the power
supply line voltage falls within a predetermined limited voltage
range.
30. The leakage protection method of claim 27, wherein the interval
is set based on a change period of the power supply line voltage or
based on a predetermined duration.
31. The leakage protection method of claim 27, wherein the manner
of detecting the sampled power supply line voltage to determine
whether the voltage of the AC input power to which the power supply
line is accessed is divided comprises: comparing the sampled power
supply line voltage with a predetermined power-off protection
voltage threshold, and determining whether the voltage of the AC
input power is divided based on the compared result.
32. The leakage protection method of claim 27, wherein the manner
of providing leakage protection based on the determined result
comprises: controlling the power supply line to be conductive when
the determined result is that the voltage of the AC input power is
not divided; and controlling the power supply line to be
non-conductive when the determined result is that the voltage of
the AC input power is divided; or controlling a drive circuit to
supply power to the load when the determined result is that the
voltage of the AC input power is not divided; and controlling the
drive circuit to give a leakage protection response when the
determined result is that the voltage of the AC input power is
divided.
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of
electronic circuit, and in particular to a leakage protection
circuit, a method and a drive device.
BACKGROUND OF THE INVENTION
[0002] LED tube lamp has dual-end power supply, when one end cap of
an LED tube lamp is inserted into a lamp socket but another is not,
an electric shock would happen if user touches the metal or
conductive parts of another end cap which is not inserted into the
lamp socket.
SUMMARY OF THE INVENTION
[0003] In view of the above shortcomings of the prior art, the
objective of the present application is to provide a leakage
protection circuit, a method and a drive device for solving the
problem of electric shock caused by touching the metal or
conductive parts of an electric appliance by mistake in man-made
operations in the prior art.
[0004] In one aspect, the present application provides a leakage
protection circuit. The leakage protection circuit is electrically
connected with the power supply line of a load, and the circuit may
be configured to sample an electrical signals from the power supply
line at intervals, detect the voltage of the sampled electrical
signals to determine whether the voltage of the AC input power is
divided, and provide leakage protection based on the determined
result.
[0005] In some embodiments, the leakage protection circuit may
comprise a detection unit, a sampling unit and a control unit. The
detection unit is connected with the power supply line, and may be
configured to detect the voltage of the power supply line and
output the sampling control signals based on the detected voltage.
The sampling unit is connected with the detection unit, and may be
configured to sample an electrical signals from the power supply
line according to the received sampling control signals. The
control unit is connected with the sampling unit, and may be
configured to compare the voltage of the sampled electrical signals
with a predetermined power-off protection voltage threshold, and
provide leakage protection response based on the compared
result.
[0006] In some embodiments, the detection unit may comprise a
limited voltage detection circuit module which is connected with
the power supply line and configured to detect the voltage of the
power supply line and output a first sampling control signal when
the detected voltage falls within a predetermined limited voltage
range.
[0007] In some embodiments, the detection unit may further comprise
a timing circuit module which is connected with the limited voltage
detection circuit module and configured to output a second sampling
control signal based on the first sampling control signal, wherein
a second sampling control signal is effective within a time
limit.
[0008] In some embodiments, the timing circuit module may be
configured to set a detection timing based on the first sampling
control signal, and output the second sampling control signal after
the detection timing is exceeded.
[0009] In some embodiments, the timing circuit module may be
configured to output the second sampling control signal within the
existence duration of the first sampling control signal.
[0010] In some embodiments, the interval may be set based on the
change period of the voltage of the power supply line or based on a
predetermined duration.
[0011] In some embodiments, the control unit may comprise a
comparison circuit module and a logic latch circuit module. The
comparison circuit module may be configured to compare the voltage
of the sampled electrical signal with the predetermined power-off
protection voltage threshold and output the compared result. The
logic latch circuit module is connected with the comparison circuit
module, and may be configured to latch the compared result and
output a corresponding latch signal. Wherein, the latch signal is
representing the leakage protection control signal generated by
leakage protection circuit.
[0012] In some embodiments, the control unit may further comprise a
switch circuit module which is connected with the logic latch
circuit module and configured to control the conductive state or
non-conductive state of the power supply line.
[0013] In some embodiments, the leakage protection circuit may be
configured to stop sampling the power supply line at intervals when
the power supply line is controlled to be conductive.
[0014] In some embodiments, the leakage protection circuit may be
an LED leakage protection circuit. The leakage protection circuit
is electrically connected with the power supply line, which
provides power for LED load. The LED leakage protection circuit may
be configured to output a leakage protection control signal based
on the determined result, in order that an LED drive circuit
electrically connected with the LED leakage protection circuit
gives a corresponding leakage protection response based on the
leakage protection control signal.
[0015] In another aspect, the present application provides a chip.
The chip may comprise multiple pins and a leakage protection
circuit. Wherein, at least one pin of the multiple pins is
electrically connected with the power supply line of a load. The
leakage protection circuit is connected with the pin and may be
configured to sample electrical signals from the power supply line
at intervals, detect the voltage of the sampled electrical signals
to determine whether the voltage of the AC input power is divided,
and provide leakage protection response based on the determined
result.
[0016] In some embodiments, the leakage protection circuit may
comprise a detection unit, a sampling unit and a control unit. The
detection unit is connected with the power supply line, and may be
configured to output the sampling control signals based on the
detection of the voltage of the power supply line. The sampling
unit is connected with the detection unit, and may be configured to
sample an electrical signals from the power supply line based on
the received sampling control signals. The control unit is
connected with the sampling unit, and may be configured to compare
the voltage of the sampled electrical signals with a predetermined
power-off protection voltage threshold and provide leakage
protection based on the compared result.
[0017] In some embodiments, the detection unit may comprise a
limited voltage detection circuit module which is connected with
the power supply line and configured to detect the voltage of the
power supply line and output a first sampling control signal when
the detected voltage falls within a predetermined limited voltage
range.
[0018] In some embodiments, the detection unit may further comprise
a timing circuit module which is connected with the limited voltage
detection circuit module and configured to output a second sampling
control signal based on the first sampling control signal, wherein
a second sampling control signal is effective within a time
limit.
[0019] In some embodiments, the interval may be set based on the
change period of the voltage of the power supply line or based on a
predetermined duration.
[0020] In some embodiments, the control unit may comprise a
comparison circuit module and a logic latch circuit module. The
comparison circuit module may be configured to compare the voltage
of the sampled electrical signal with the predetermined power-off
protection voltage threshold and output the compared result. The
logic latch circuit module is connected with the comparison circuit
module, and may be configured to latch the compared result and
output a corresponding latch signal. Wherein, the latch signal is
representing the leakage protection control signal generated by the
leakage protection circuit.
[0021] In some embodiments, the control unit may further comprise a
switch circuit module which is connected with the logic latch
circuit module and configured to control the conductive state or
non-conductive state of the power supply line.
[0022] In some embodiments, the leakage protection circuit may be
an LED leakage protection circuit, and is electrically connected
with the power supply line of an LED load via the pin.
[0023] In yet another aspect, the present application provides a
drive device. The drive device may comprise a rectifying circuit, a
leakage protection circuit and a drive circuit. The rectifying
circuit may be configured to rectify the accessed AC and then
provide to the power supply line of a load. The leakage protection
circuit is connected with the power supply line and may be
configured to sample electrical signals from the power supply line
at intervals, detect the voltage of the sampled electrical signals
to determine whether the voltage of the AC input power is divided,
and provide leakage protection response based on the determined
result. The drive circuit is connected with the leakage protection
circuit and may be configured to control the power supply line to
supply power to the load.
[0024] In some embodiments, the leakage protection circuit may
comprise a detection unit, a sampling unit and a control unit. The
detection unit is connected with the power supply line, and may be
configured to output the sampling control signals based on the
detection of the voltage of the power supply line. The sampling
unit is connected with the detection unit, and may be configured to
sample an electrical signals from the power supply line based on
the received sampling control signals. The control unit is
connected with the sampling unit, and may be configured to compare
the voltage of the sampled electrical signals with a predetermined
power-off protection voltage threshold and provide leakage
protection based on the compared result.
[0025] In some embodiments, the detection unit may comprise a
limited voltage detection circuit module which is connected with
the power supply line and configured to detect the voltage of the
power supply line and output a first sampling control signal when
the detected voltage falls within a predetermined limited voltage
range.
[0026] In some embodiments, the detection unit may further comprise
a timing circuit module which is connected with the limited voltage
detection circuit module and configured to output a second sampling
control signal based on the first sampling control signal, wherein
a second sampling control signal is effective within a time
limit.
[0027] In some embodiments, the control unit may comprise a
comparison circuit module and a logic latch circuit module. The
comparison circuit module may be configured to compare the voltage
of the sampled electrical signal with the predetermined power-off
protection voltage threshold and output the compared result. The
logic latch circuit module is connected with the comparison circuit
module, and may be configured to latch the compared result and
output a corresponding latch signal. Wherein, the latch signal is
representing the leakage protection control signal generated by the
leakage protection circuit.
[0028] In some embodiments, the leakage protection circuit may be
configured to output the leakage protection control signal to the
drive circuit; and the drive circuit gives a corresponding leakage
protection response based on the leakage protection control
signal.
[0029] In some embodiments, the drive circuit may comprise an
enable control unit. The enable control unit may be configured to
give a corresponding leakage protection response based on the
leakage protection control signal when the leakage protection
circuit outputs the leakage protection control signal.
[0030] In one aspect, the present application provides a leakage
protection method. The leakage protection method may comprise:
sampling the power supply line of a load at intervals; detecting
the voltage of the sampled electrical signals to determine whether
the voltage of the AC input power is divided; and providing leakage
protection based on the determined result.
[0031] In some embodiments, the manner of sampling the power supply
line of a load at intervals may comprise: performing limited
voltage detection on the voltage of the power supply line; and
acquiring the sampled electrical signals from the power supply line
based on the result of limited voltage detection.
[0032] In some embodiments, the manner of acquiring the sampled
electrical signals from the power supply line based on the result
of limited voltage detection may comprise: acquiring the sampled
electrical signals from the power supply line after a predetermined
detection timing is exceeded and the voltage of the power supply
line falls within a predetermined limited voltage range.
[0033] In some embodiments, the interval may be set based on the
change period of the voltage of the power supply line or based on a
predetermined duration.
[0034] In some embodiments, the manner of detecting the voltage of
the sampled electrical signals to determine whether the voltage of
the AC input power is divided may comprise: comparing the voltage
of the sampled electrical signals with a predetermined power-off
protection voltage threshold, and determining whether the voltage
of the AC input power is divided based on the compared result.
[0035] In some embodiments, the manner of providing leakage
protection based on the determined result may comprise: controlling
the power supply line to be conductive when the determined result
is that the voltage of the AC input power is not divided; and
controlling the power supply line to be non-conductive when the
determined result is that the voltage of the AC input power is
divided; or controlling the drive circuit to supply power to the
load when the determined result is that the voltage of the AC input
power is not divided; and controlling the drive circuit to give a
leakage protection response when the determined result is that the
voltage of the AC input power is divided.
[0036] As mentioned above, the leakage protection circuit, the
method and the drive device in the present application have the
following beneficial effects: through sampling the electric signals
from the power supply line at intervals and performing voltage
detection and comparasion to determine whether the voltage of the
accessed AC input power is divided, when the voltage of the
accessed AC input power is determined to be divided, the power
supply line will be controlled in non-conductive state, thereby
prevent human from electric shock.
BRIEF DESCRIPTION OF THE DRAWINGS
[0037] The novel features of the invention are set forth with
particularity in the appended claims. A better understanding of the
features and advantages of the present invention will be obtained
by reference to the following detailed description that sets forth
illustrative embodiments, in which the principles of the invention
are employed, and the accompanying drawings (also "figure" and
"Fig." herein), of which:
[0038] FIG. 1 is a schematic diagram showing the connection
relationship when the LED tube lamp is accessed to the AC input
power.
[0039] FIG. 2 is a schematic diagram of the structural framework of
the leakage protection circuit in one embodiment in the present
application.
[0040] FIG. 3 is a structural schematic diagram of the limited
voltage detection circuit module in the leakage protection circuit
in the present application in one embodiment.
[0041] FIG. 4 shows a timing sequence schematic diagram of the
limited voltage detection circuit module and the timing circuit
module represented by respectively utilizing the waveforms of the
first sampling control signal and the second sampling control
signal according to the leakage protection circuit in one
embodiment in the present application.
[0042] FIG. 5 is a structural schematic diagram of the timing
circuit module in one embodiment of the leakage protection circuit
in the present application in one embodiment.
[0043] FIG. 6 is a waveform schematic diagram of the relationship
between the second sampling control signal output by the timing
circuit module and the first sampling control signal in one
embodiment of the present application.
[0044] FIG. 7 is a structural schematic diagram of the timing
circuit module in another embodiment of the leakage protection
circuit of the present application in one embodiment.
[0045] FIG. 8 is a structural schematic diagram of the leakage
protection circuit in the present application in one
embodiment.
[0046] FIG. 9 is a waveform schematic diagram of the relationship
between the voltage of the sampled electrical signals and the
power-off protection voltage threshold when the leakage protection
circuit in the present application detects voltage of AC input
power is divided or not.
[0047] FIG. 10 is a structural schematic diagram of the leakage
protection circuit in the present application in another
embodiment.
[0048] FIG. 11 is a schematic diagram of a packaging structure of
the chip containing the leakage protection circuit of the present
application in one embodiment.
[0049] FIG. 12 is a frame structural schematic diagram of the drive
device in the present application in one embodiment.
[0050] FIG. 13 is a structural schematic diagram of the circuit of
the drive device in the present application in one embodiment.
[0051] FIG. 14 is a flow chart of the leakage protection method in
the present application in one embodiment.
[0052] FIG. 15 is a flow chart of the drive method in the present
application in one embodiment.
[0053] FIG. 16 is a structural schematic diagram of the leakage
protection circuit and the drive circuit.
[0054] FIG. 17 is another structural schematic diagram of the
leakage protection circuit and the drive circuit.
DETAILED DESCRIPTION
[0055] While various embodiments of the invention have been shown
and described herein, it will be obvious to those skilled in the
art that such embodiments are provided by way of example only.
Numerous variations, changes, and substitutions may occur to those
skilled in the art without departing from the invention. It should
be understood that various alternatives to the embodiments of the
invention described herein may be employed.
[0056] The implementation of the present application is described
below via specific embodiments, and those skilled in the art can
easily understand other advantages and effects of the present
application through the contents disclosed in the present
description.
[0057] Electric leakage caused by man-made operations usually
occurs during the assembly operation of loads. With the connection
relationship when the LED tube lamp including drive device being
connected with AC input power as shown in FIG. 1 as an example, the
LED tube lamp is internally provided with a drive device and an LED
load, and the two end caps of the LED tube lamp are respectively
connected with a lamp sockets (namely, a live wire end and a
neutral wire end) of an AC input power. In the assembly process of
the above connection relationship, when people insert one end cap
of an LED tube lamp into lamp socket, they may concentrate on
assembling the needle-shaped pin of the LED tube lamp and neglect
the handheld position on the tube lamp, and when one end cap of the
tube lamp is inserted onto the lamp socket, they may mistouch the
metal or conductive parts of other end cap of the LED tube lamp
which is not inserted into the lamp socket, thereby giving rise to
the danger of electric shock.
[0058] In order to avoid the potential electric leakage existing in
the assembly processes of electrical appliances similar to the
above assembling connection methods, with the assembling connection
methods of the LED tube lamp as an example, the present application
provides a leakage protection circuit. The leakage protection
circuit is used for being accessed to the power supply line of the
load, sampling an electrical signal from the power supply line at
intervals, detecting the voltage of the sampled electrical signals
to determine whether the voltage of the AC input power is divided
or not, and controlling the conductive state of the power supply
line based on the determined result. With the LED load as an
example, the leakage protection circuit is an LED leakage
protection circuit and is configured to provide leakage protection
for the user and the LED load when the LED load is connected to the
power supply line. The leakage protection circuit provided by the
present application can be used as an LED leakage protection
circuit and can be connected with the power supply line, which is
coupled to the LED load. Wherein the power supply line mainly
converts the rectified current into an operating current to drive
the load after the AC is rectified, the power supply line is not
only provided with a conductor loop which enables the current to be
output to the ground wire from the rectifying circuit, but also is
provided with an electrical appliance which is arranged on the
conductor loop and used for supplying power to the load, wherein
the power supply line further includes a leakage protection
circuit.
[0059] Herein, the leakage protection circuit can be arranged
inside the drive device of an electrical appliance, wherein the
drive device can perform energy conversion on the AC provided by
the AC input power to provide power supply to the load. With the
LED drive device as an example, based on the operating voltage of
the LED load, the LED drive device provides corresponding power
supply to the LED load. The LED leakage protection circuit is
arranged inside the LED drive device. For example, the LED leakage
protection circuit is arranged in the LED drive device, and is
electrically connected with the power supply line which is
connected to a rectifying circuit. When the two end caps of an LED
tube lamp are not accessed to the AC input power at the same time,
the leakage protection circuit enables the whole power supply line
to be in non-conductive state in which the load can operate. Within
a short time after being accessed to the AC input power, whether
electric leakage occurs should be detected, if no electric leakage
occurs, then the power supply line is in conductive state in which
the load can operate, otherwise, the state in which the power
supply line to be in non-conductive state in which the load can
operate is maintained.
[0060] In the above example, the leakage protection circuit samples
the electrical signals from the power supply line at intervals,
wherein the power supply line is connected to the rectifying
circuit to get the rectified voltage; and detects whether the
voltage of the AC input power accessed by the electrical appliance
is divided or not based on the voltage of the sampled electrical
signals; when the voltage of the AC input power is determined to be
divided based on the detection result, leakage protection is
provided, thereby effectively preventing the electric leakage
danger occurred during unintended touch by human bodies; when the
voltage of the AC input power is determined to be not divided based
on the detection results, the power supply line is controlled to be
in conductive state, thereby realizing providing operating power
supply to the load.
[0061] Herein, the sampling interval of the leakage protection
circuit can be set based on the voltage change period of the power
supply line. For example, the electrical signals can be sampled at
the voltage peak or the valley in each rectified voltage change
period or in at least every rectified voltage change period, or the
electrical signals can be sampled in the fixed voltage area between
the voltage peak and the valley in each rectified voltage change
period or in at least every rectified voltage change period.
Wherein in order to ensure that human bodies will not be damaged by
continuous electric shock during unintended touch period, the
sampling interval is a millisecond or even a microsecond, for
example, the sampling interval may be every half of a voltage
change period, every one voltage change period or every multiple
voltage change periods. The sampling interval can be realized
through the circuit structure which is designed by utilizing the
voltage change period in the leakage protection circuit. Or, the
sampling interval is set according to the predetermined duration.
For example, the leakage protection circuit contains a capacitor
and a resistor, and the sampling interval is determined based on
the charging duration of the capacitor; wherein the technicians can
design corresponding sampling intervals through assembling a
resistor. The resistor can be an adjustable resistor or a fixed
resistor.
[0062] Herein, in the voltage detection manner of the leakage
protection circuit, the sampled voltage can be compared with the
predetermined reference voltage corresponding to the sampling
instant to determine whether the voltage of the AC input power is
divided or not, so as to determine the conductive or non-conductive
state of the power supply line connected to the load. For example,
when detecting the voltage of the power supply line is zero, the
leakage protection circuit starts the timing of the sampling
interval, samples the electrical signals from the power supply line
when timing reaches, determines the voltage threshold when timing
reaches based on the voltage change period of the power supply
line, and compares the voltage of the sampled electrical signals
with the voltage threshold to determine whether the voltage of the
AC input power is divided or not. When the voltage of the AC input
power is determined to be divided, the leakage protection circuit
can output the leakage protection control signals to control the
other circuits connected with the power supply line to suspend
operating or control the power supply line to be in non-conductive
state. Wherein the other circuits include but are not limited to a
drive circuit and a filter circuit, etc. With the leakage
protection circuit of the LED load as an example, the LED leakage
protection circuit is used for electrically connecting to the power
supply line of the LED load, the LED leakage protection circuit
outputs the leakage protection control signals based on the
determined compared results, such that the LED drive circuit
electrically connected with the LED leakage protection circuit can
give corresponding leakage protection response based on the leakage
protection control signals. For example, the drive circuit includes
an enable control unit, the controlled terminal of the enable
control unit is connected with the output terminal of the leakage
protection circuit and is connected with the switch device or logic
device in the drive circuit, when receiving the leakage protection
control signals, the enable control unit controls the switch device
in the drive circuit to be non-conductive, such that the energy
converted by the drive circuit cannot be provided to the load until
the leakage protection control signal is invalid, and the switch
device is switched into a conductive state, at this time, the drive
circuit can execute the drive operation to provide power for the
load. For another example, the drive circuit contains an enable
control unit, the controlled terminal of the enable control unit is
connected with the output terminal of the leakage protection
circuit to receive the leakage protection control signal, the input
terminal of the enable control unit is connected with the power
supply terminal of the drive circuit, and the output terminal of
the enable control unit is grounded; and when the leakage
protection circuit outputs the leakage protection control signal,
the enable control unit gives corresponding leakage protection
response based on the leakage protection control signal, namely,
the power supply terminal of the drive circuit is grounded such
that the active device in the drive circuit can not reach its
operating voltage, that is, the drive circuit can not execute the
drive operation to provide power for the load.
[0063] Herein, the leakage protection circuit samples the voltage
of the electrical signals based on the sampling interval set
according to the voltage change period, and can determine whether
the voltage of the AC input power is divided or not by comparing
the voltage of the electrical signals with the predetermined
power-off protection voltage threshold. Therefore, please refer to
FIG. 2 which is a schematic diagram of the structural framework of
the leakage protection circuit in one embodiment. As shown in the
figure, the leakage protection circuit includes: a detection unit
11, a sampling unit 12 and a control unit 13.
[0064] The detection unit 11 is connected with the power supply
line, and is configured to output sampling control signals based on
the detection of the voltage of the power supply line. Herein, the
detection unit 11 can detect the change of the voltage of the power
supply line in real time, and determine to reach the sampling
interval when detecting that the voltage changes to the
predetermined reference voltage value and output the sampled
control signals. Wherein the predetermined reference voltage value
can also be equal to any voltage value correspond to the voltage
change period, such as the peak value, the valley value and the
intermediate value. The sampling unit performs sampling operations
based on the sampling control signal.
[0065] In some embodiments, the detection unit includes a limited
voltage detection circuit module connected with the power supply
line, and is configured to detect the voltage of the power supply
line, and output the first sampling control signal when the
detected voltage falls within the predetermined limited voltage
range, wherein the limited voltage range is intercepted in the
voltage change range of the power supply line, for example, the
limited voltage range is [V1,V2], wherein 0.ltoreq.V1<V2<V
max, and V max is the maximum value in the voltage change
range.
[0066] In order to realize the above limited voltage detection, the
limited voltage detection circuit module includes at least one
comparator, and the comparator is configured to compare whether the
voltage of the power supply line falls in the predetermined limited
voltage range, wherein the comparator is configured to provide the
boundary threshold of the limited voltage range. The comparator can
be a hysteresis comparator, a window comparator or a zero-crossing
comparator, etc. In some embodiments, the limited voltage detection
circuit module is a valley bottom detection circuit designed based
on the sine wave changes. For example, please refer to FIG. 3 which
is a structural schematic diagram of the limited voltage detection
circuit module. As shown in FIG. 3, the limited voltage detection
circuit module includes a zero-crossing comparator, the negative
input terminal of the zero-crossing comparator is accessed to the
boundary threshold of the limited voltage range, the positive input
terminal of the zero-crossing comparator is connected with the
power supply line directly or via a circuit containing a sampling
resistor, and when the voltage change of the power supply line is
smaller than the boundary threshold, the first sampling control
signal is output. Wherein the boundary threshold is greater than
zero, such that the first sampling control signal maintains for an
effective duration, and meanwhile triggering or no triggering by
mistake caused by unstable voltage of the power supply line can be
tolerated. The sampling unit can sample the electrical signals from
the power supply line based on the rising edge or the falling edge
of the first sampling control signal, or can continuously sample
the electrical signals in the effective duration of the first
sampling control signal. The sampling unit can perform the sampling
operation once in each voltage change period based on the first
sampling control signal.
[0067] In still some other embodiments, the detection unit further
includes a timing circuit module. The timing circuit module is
connected with the limited voltage detection circuit module and is
configured to output a second sampling control signal based on the
first sampling control signal, wherein a second sampling control
signal is effective within a time limit. The timing circuit module
outputs the second sampling control signal when the rising edge of
the first sampling control signal is detected, and the sampling
unit samples the electrical signals when the second sampling
control signal is effective. Wherein, the second sampling control
signal is generated from the first sampling control signal, and the
second sampling control signal is effective within a time limit,
which is preset by the timing circuit based on the effective
duration of the first sampling control signal. In addition, the
effective duration of the second sampling control signal is deemed
as the sampling duration allowed by the sampling unit. The limit of
the sampling duration can effectively prevent mis-connectivity
operations caused by jittering of the sampled electrical signals.
For example, with reference to FIG. 4 which is a timing sequence
schematic diagram of the limited voltage detection circuit module
and the timing circuit module represented by respectively utilizing
the waveforms of the first sampling control signal and the second
sampling control signal. The timing circuit module outputs the
second sampling control signal when the rising edge of the first
sampling control signal is detected, and times the existence
duration of the second sampling control signal, in the timing
duration, the sampling unit samples the electrical signals. Wherein
in order to prevent mis-connectivity operations caused by jittering
of the sampled electrical signals, the timing circuit module
outputs the second sampling control signal within the existence
duration of the first sampling control signal, namely, the
existence duration of the second sampling control signal is shorter
than the existence duration of the first sampling control signal.
The sampling unit samples the electrical signals based on the
second sampling control signal.
[0068] In some specific examples, the timing circuit module
contains a clock signal generator, a counter 1, a logic device
group and a switch and the like, wherein the switch is on with the
limited voltage detection circuit module, the switch is on with the
control terminal of the counter 1, the input terminal of the
counter 1 is connected with the clock signal generator, and the
output terminal of the counter 1 is connected with the logic device
group, wherein the switch is controlled to be on or off based on
the first sampling control signal, when the switch is on, the
counter 1 begins to count the received clock signals, and before
the number of pulses of the clock signals counted by the counter 1
reaches the predetermined value, the logic device group outputs the
second sampling control signal; and when the number of pulse
signals counted by the counter 1 reaches its count value, the logic
device group is controlled not to output the second sampling
control signal, until the next first sampling control signal
arrives.
[0069] In still some specific examples, please refer to FIG. 5
which is a structural schematic diagram of the timing circuit
module in one embodiment. As shown in the figure, the timing
circuit module contains a capacitor, a capacitor charge controller,
a capacitor discharge controller, two comparators, a logic device
group and the like, wherein the capacitor discharge controller is
connected a capacitor in parallel; the control terminal of the
capacitor charge controller receives the first sampling control
signal, the input terminal is accessed to a constant voltage, and
the output terminal is connected to a capacitor; one end of the
capacitor is grounded directly or via a resistor; the another end
of capacitor is also connected to the negative input terminal
comparators A1 and A2; wherein another positive input terminal of
the comparator A1 is accessed to the reference voltage Vref 1,
while another positive input terminal of the comparator A2 is
accessed to the reference voltage Vref 2; the output terminal of
the comparators A1 and A2 are both connected with the logic device
group, and the logic device group outputs the second sampling
control signal, wherein the capacitor charge controller and the
capacitor discharge controller can both be a controlled switch,
such as an MOSFET. The reference voltage Vref 1 approaches 0V,
while Vref 2 is a voltage value greater than Vref 1. Through the
design of the technicians, the duration of the capacitor voltage
rising from Vref 1 to Vref 2 is shorter than the existence duration
of the first sampling control signal. In the initial period, the
capacitor discharge controller is short connected to a capacitor
and the capacitor charge controller is disconnected, such that the
capacitor is in a zero charge state, correspondingly, the
comparator A1 outputs the low level; when the capacitor charge
controller receives the first sampling control signal, the
capacitor charge controller is conductive and the capacitor
discharge controller is non-conductive, such that the capacitor is
charged, when the capacitor voltage is higher than the reference
voltage Vref 1, the comparator A1 outputs the high level while the
comparator A2 still outputs the low level, and when the comparator
A1 outputs the high level while the comparator A2 outputs the low
level, the logic device group outputs the second sampling control
signal based on the predetermined logic configuration; the
capacitor continues to be charged, such that when the voltage of
the capacitor reaches the Vref 2, the comparator A2 jumps to the
high level, and when the comparators A1 and A2 both output the high
level, based on the logic configuration, the logic device group
will not output the second sampling control signal, and controls
the capacitor charge controller to be off so that the capacitor is
not charged, and controls the capacitor discharge controller to be
on so as to discharge the electric charge of the capacitor, until
the next first sampling control signal arrives.
[0070] In still some other embodiments, the timing circuit module
further sets the detection timing based on the first sampling
control signal, and outputs the second sampling control signal
after the detection timing is exceeded. Please refer to FIG. 6
which is a waveform schematic diagram of the relationship between
the second sampling control signal output by the timing circuit
module and the first sampling control signal. As shown in the
figure, wherein the detection timing can enable that, within at
least in one time interval T2 of first sampling control signal, the
timing circuit module does not output the second sampling control
signal based on the first sampling control signal. Therefore, the
existence duration of the detection timing is the minimum time
interval of the second sample control signal, and the timing
circuit module can output the second sampling control signal in the
case that the detection timing is exceeded and the first sampling
control signal is effective, that is, the timing circuit module can
output the second sampling control signal based on the first sample
control signal only if the minimum time interval is satisfied.
Further, the sampling interval may be set based on the change
period of the voltage of the power supply line or based on a
predetermined duration, the minimum time interval also may be set
based on the change period of the voltage of the power supply line
or based on a predetermined duration.
[0071] Based on the technical concept mentioned above, the timing
circuit module may further set a sampling interval T3, during which
the limited voltage detection circuit module detects a voltage of
the power supply line and outputs a first sampling control signal
when the detected voltage falls within a predetermined limited
voltage range. For example, the timing circuit module is configured
to start the sampling interval T3 after T2 is exceeded, instruct
the limited voltage detection circuit module to detect the voltage
of the power supply line within T3, and output a first sampling
control signal when the detected voltage falls within a
predetermined limited voltage range. The timing circuit module is
configured to output a second sampling control signal based on the
received first sampling control signal, and start the time T2 and
perform loop operation.
[0072] In some specific examples, the timing circuit module
contains multiple counters, wherein one counter 1 is used for
counting the existence duration of the second sampling control
signal, while the other counter 2 is used for counting the
detection timing. The timing circuit module further includes a
clock signal generator, a switch and a logic device group. The
switch is controlled to be on or off based on the first sampling
control signal, when the switch is on, the counter 1 begins to
count the received clock signals, and before the number of pulses
of the clock signals counted by the counter 1 reaches the
predetermined value, the logic device group outputs the second
sampling control signal; and when the number of pulse signals
counted by the counter 1 reaches its count value, the logic device
group is controlled not to output the second sampling control
signal, at this time, the counter 2 begins to count the number of
pulses of the received clock signals; when the counter 2 reaches
its count value, namely, the detection timing is exceeded, the
logic device group is controlled to output the second sampling
control signal.
[0073] In still some other specific examples, please refer to FIG.
7 which is a structural schematic diagram of the timing circuit
module in another embodiment. As shown in the figure, the timing
circuit module can contain multiple capacitors, and each capacitor
is configured with a capacitor charge controller and a capacitor
discharge controller, multiple comparators and a logic device
group, etc. Wherein the configured capacitor discharge controller
is connected to a corresponding capacitor in parallel; the control
terminal of the configured capacitor charge controller receives the
first sampling control signal, the input terminal is accessed to a
constant voltage and the output terminal is connected with a
corresponding capacitor; one end of each of the capacitors is
grounded directly or via a resistor; another end of the capacitors
C1 is further connected with the negative input terminal of the
comparators A1 and A2; wherein the positive input terminal of the
comparator A1 is accessed to the reference voltage Vref 1, the
positive input terminal of the comparator A2 is accessed to the
reference voltage Vref 2; the negative input terminal of comparator
A3 is connected with another capacitor C2 and the positive input
terminal is accessed to the reference voltage Vref 3; the output
terminal of the comparators A1, A2 and A3 are all connected with
the logic device group, and the logic device group outputs the
second sampling control signal, wherein the reference voltage Vref
1 approaches 0V, and Vref 2 is a voltage value greater than Vref 1.
Through the design of the technicians, the duration of the voltage
of the capacitor C1 rising from Vref 1 to Vref 2 is shorter than
the existence duration of the first sampling control signal; and
the duration of the voltage of the capacitor C2 from the initial
value (such as 0V) to Vref 3 is longer than the existence duration
of a first sampling control signal. In the initial period, the
capacitor discharge controller CDC1 is short connected to the
capacitor C1 and the capacitor charge controller CCC1 is off, such
that the capacitor C1 is in a zero charge state, meanwhile, the
capacitor discharge controller CDC2 connected with the capacitor C2
is off and the capacitor charge controller CCC2 is on, such that
the capacitor C2 is in a charge saving state; correspondingly, the
comparators A1 and A2 output the low level while the comparator A3
outputs the high level; when the capacitor charge controller CCC1
connected with the capacitor C1 receives the first sampling control
signal, the capacitor charge controller CCC1 connected with the
capacitor C1 is on and the capacitor discharge controller CDC1 is
off, such that the capacitor C1 is charged. When the voltage of the
capacitor C1 is higher than the reference voltage Vref 1, the
comparator A1 outputs the high level and the comparator A2 still
outputs the low level, and when the comparators A1 and A3 output
the high level and the comparator A2 outputs the low level, the
logic device group outputs the second sampling control signal based
on the predetermined logic configuration; at this time, the
capacitor discharge controller CDC2 and the capacitor charge
controller CCC2 enable the capacitor C2 to discharge based on the
second sampling control signal, and the comparator A3 outputs the
low level; however, the capacitor C1 continues to be charged, such
that when the voltage reaches Vref 2, the comparator A2 jumps to
the high level, and when the comparators A1 and A2 both output the
high level and the comparator A3 outputs the low level, based on
the logic configuration, the logic device group does not output the
second sampling control signal, controls the capacitor charge
controller CCC1 to be off such that the capacitor C1 is not
charged, and controls the capacitor discharge controller CDC1 to be
on to discharge the charge of the capacitor C1. When the capacitor
C1 is discharged, the capacitor charge controller CCC2 of the
capacitor C2 is on and the capacitor discharge controller CDC2 is
off such that the capacitor C2 is charged, until the voltage of the
capacitor C2 reaches Vref 3, then the comparator A3 outputs the
high level, and when the comparator A3 outputs the high level,
based on the logic configuration, the logic device group outputs
the second sampling control signal based on the change of the level
of the comparators A1 and A2.
[0074] It should be noted that, the circuit structure of the timing
circuit module mentioned above is only exemplary, rather than
limiting the circuit structure of the timing circuit module in the
present application. In fact, based on the design of the timing
logic by the technicians, other timing circuit modules including a
comparator, a logic device group and a capacitor can also be
proposed; or, the timing circuit module containing a clock signal
generator and a counter can also be proposed, which are not
elaborated herein, however, the timing circuit module designed
based on the technical enlightment of the above timing circuit
module should be deemed as the specific example of the present
application. In addition, the devices in the above timing circuit
module can be included in the leakage protection circuit. To
facilitate the periods of various ACs provided by different AC
input powers, the devices used for timing, such as a capacitor and
the peripheral devices or a counter, in the timing circuit module
can be selected by the technicians based on the requirements of
specific designs. Based on the design of the above timing circuit
modules, one example is as follows: the sampling unit included in
the leakage protection circuit samples the voltage of the
electrical signals from the power supply line during the period in
which the second sampling control signal is received.
[0075] It should also be noted that, as required by actual logic
design, the logic device group mentioned in any of the above
examples can contain at least one logic device, and all the logic
devices are electrically connected to realize corresponding logic
configuration, wherein the logic devices include but are not
limited to an AND gate, an OR gate, a NAND gate, a NOT gate, an
encoder, a decoder, a selector, etc.
[0076] The sampling unit is connected with the detection unit and
is configured to sample the electrical signals from the power
supply line based on the received sampling control signals.
[0077] Please refer to FIG. 8 which is a structural schematic
diagram of the leakage protection circuit in one embodiment. As
shown in the figure, wherein the sampling unit 12 contains a
controlled switch and a sampling resistor, wherein the control
terminal of the controlled switch is connected with the output
terminal of the detection unit, one access terminal of the
controlled switch is connected with the power supply line, while
the other access terminal is grounded via the sampling resistor,
and the sampling resistor is further connected with the control
unit 13. Wherein the controlled switch includes but is not limited
to any one of a triode (BJT), a junction field effect transistor
(JFET), a depletion MOSFET and thyristor. When the detection unit
11 outputs a sampling control signal, the controlled switch is on,
and the control unit 13 acquires the voltage of the sampled
electrical signals from the sampling resistor.
[0078] In one specific example, as shown in FIG. 8, the controlled
switch is an MOSFET as an example, the gate of the MOSFET is
connected with the output terminal of the detection unit, while the
drain of the MOSFET is connected with the power supply line and the
source is connected with the sampling resistor. Wherein based on
the detection unit described above, the MOSFET is on when receiving
the first sampling control signal or the second sampling control
signal, such that the control unit 13 acquires the sampled voltage
of the electrical signals from the power supply line.
[0079] The control unit is configured to compare the voltage of the
sampled electrical signals with the predetermined power-off
protection voltage threshold and providing leakage protection based
on the compared results.
[0080] Herein, the power-off protection voltage threshold
predetermined by the control unit can be supplied by a constant
voltage circuit. The power-off protection voltage threshold can be
designed based on the fact that the value of voltage drop of the
sampling unit will be influenced by the division of the AC input
power by human bodies. When the control unit determines that the
sampled voltage is lower than the power-off protection voltage
threshold, the power supply line may be controlled to be in
non-conductive state or the leakage protection control signals may
be output; otherwise, the power supply line is in conductive state
so as to enable the load to operate normally.
[0081] In one embodiment, the control unit contains a comparison
circuit module, a logic latch circuit module and a switch circuit
module, wherein the comparison circuit module is configured to
compare the voltage of the sampled electrical signals with the
predetermined power-off protection voltage threshold and output the
compared results. The logic latch circuit module is connected with
the comparison circuit module and is configured to latch the
compared results. The switch circuit module is connected with the
logic latch circuit module and is configured to control the
conductive state or non-conductive state of the power supply line
based on the latch signals.
[0082] Please refer to FIG. 9 which shows a waveform schematic
diagram of the voltage of sampled electrical signals received by
the comparison circuit module when voltage division is generated at
the AC input power side due to man-made misoperation and when the
load is connected to the power supply line normally with no
man-made voltage division, corresponding to the leakage protection
circuit as shown in FIG. 8. As shown in the figure, when the load
is connected to the power supply line with no man-made
misoperation, the sampled voltage is higher than the power-off
protection voltage threshold Vref; when the load is connected to
the power supply line with man-made misoperation, the sampled
voltage is lower than the power-off protection voltage threshold
Vref due to voltage division by human bodies. When the sampled
voltage is higher than the power-off protection voltage threshold
Vref, the comparison circuit module outputs a jumping signal, the
logic latch circuit module latches the jumping signal and outputs
the latch signal to a switch circuit module, and the switch circuit
module controls the power supply line to be in conductive state,
otherwise, the comparison circuit module does not output a jumping
signal, the logic latch circuit module does not output latch
signals, and the switch circuit module maintains the non-conductive
state of the power supply line, thereby protecting the safety of
the load and human.
[0083] In a specific example, the comparison circuit module
includes a comparator, and the switch circuit module includes the
controlled switch and a switch drive module, the negative input
terminal of the comparator is accessed to the power-off protection
voltage threshold and the positive input terminal of the comparator
is connected to the sampling unit to get the voltage of the sampled
electrical signals, the output terminal of the comparator is
connected to the input terminal of the logic latch circuit, and the
output terminal of the logic latch circuit module is connected to
the switch drive module. The switch circuit module includes a gate
drive module and an MOSFET as an example, the gate of the MOSFET is
connected with the output terminal of the logic latch circuit
through the gate drive module, and the source and the drain are
connected with the two ends of the power supply line, that is, the
MOSFET is a necessary part of the power supply line, the current
flow through the MOSFET. When there is no voltage division is
generated at the AC input power side, the comparator always outputs
the high level, and the MOSFET is turned on and the power supply
line is in conductive state such that the load works normally. In
another embodiment, the gate of the MOSFET is connected with the
output terminal of the comparator through the gate drive module and
the like. Please refer to FIG. 10 which is a structural schematic
diagram of the leakage protection circuit in another embodiment,
wherein the logic latch circuit module latches a high level state
when the comparison circuit module outputs the jump signal from a
low level to a high level, and latches a low level state when the
comparison circuit module outputs the jump signal from a high level
to a low level. In the initial period, the logic latch circuit
module is in a low level state, and the switch circuit module cuts
off the power supply line based on the received latch signals in a
low level state; and when the comparison circuit module outputs the
jump signal from a low level to a high level, the logic latch
circuit module latches the high level state and outputs the latch
signals in a high level state, then the switch circuit module is on
such that the power supply line is in conductive state. Therefore,
it can be seen that the latch signal is representing the leakage
protection control signal generated by the leakage protection
circuit.
[0084] Herein, the MOSFET in the controlled switch can also be
substituted into any one of a triode (BJT), a junction field effect
transistor (JFET), a depletion MOSFET and a thyristor. The switch
drive module is not necessarily a gate drive module, but can be
adjusted based on the actual design requirements. For example, the
switch circuit module includes an MOSFET and a source drive module,
etc.
[0085] In some other embodiments, the output terminal of the logic
latch circuit module is connected with the other circuits (such as
the drive circuit described above) connected with the power supply
line, such that the other circuits provide corresponding leakage
protection based on the latch signals, and this will not be
repeated redundantly herein.
[0086] It should be noted that, the comparative relationship
between the voltage of the sampled electrical signal with voltage
division by human bodies and the power-off protection voltage
threshold and the comparative relationship between the sampled
electrical signal voltage with no voltage division by human bodies
and the power-off protection voltage threshold as shown in the
above FIG. 9 are related to the circuit structure of the sampling
unit. When the circuit structure of the sampling unit is configured
in such a way that the voltage of the sampled electrical signals
with voltage division by human bodies is higher than the voltage of
the sampled electrical signals with no voltage division by human
bodies, the corresponding control unit should provide corresponding
leakage protection based on the compared results contrary to those
shown in FIG. 9. Wherein the circuit structure of the sampling unit
can also be of a connection manner in which one access terminal of
the controlled switch is connected to the power supply line via a
sampling resistor while the other access terminal of the controlled
switch is grounded, and the connection manners will not be
enumerated herein.
[0087] In order to prevent the logic latch circuit module from
providing wrong latch signals in the restarting operation after
users turn off the electrical appliance, when the power supply for
the load is interrupted, the logic latch circuit module needs to
reset to the initial low level state. In some specific examples,
the logic latch circuit module resets based on the fact that the
leakage protection circuit is in an undervoltage state.
[0088] Wherein the undervoltage state is a state in which the
voltage of the load cannot reach its normal working voltage due to
the influence of external factors or electrical appliance
components connected with or located on the power supply line in
the normal operating period of the load, such that the load is in a
state of not operating. The undervoltage state of the leakage
protection circuit is caused by man-made power failure or by
abnormity of the electrical appliance components inside (or
outside) the leakage protection circuit. For example, the instances
enabling the leakage protection circuit to be in an undervoltage
state include but are not limited to the power-off state of the
leakage protection circuit in the power off period and the state of
the leakage protection circuit when the power supply system cannot
provide corresponding operating voltage to the active device in the
leakage protection circuit.
[0089] The logic circuit module can reset the latched signals
through detecting the undervoltage state of the leakage protection
circuit. In one specific example, the reset terminal of the logic
latch circuit module is connected with a power supply line, when
the power supply of the power supply line is interrupted, the
leakage protection circuit is in an undervoltage state, and the
reset terminal of the logic circuit module receives effective reset
signals. In another specific example, the reset terminal of the
logic latch circuit module is connected with the undervoltage
protection circuit used for protecting the leakage protection
circuit, and when the undervoltage protection circuit generates
undervoltage protection signals due to the detection of an
undervoltage state of the leakage protection circuit, the reset
terminal of the logic latch circuit module takes the undervoltage
protection signal as the effective reset signal, thereby realizing
the reset operation of the logic latch circuit module.
[0090] In addition, due to the logic latch circuit module, when the
power supply line is in conductive state, the detection unit and
the sampling unit are not necessarily required to continuously
provide voltage of the electrical signals to continuously control
the on or off state of the switch circuit unit. Therefore, the
sampling of the power supply line at intervals is stopped when the
power supply line is controlled to be conductive. Wherein the
leakage protection circuit can add a control circuit module in the
detection unit or a sampling unit to correspondingly stop the
detection or sampling. In some specific examples, the control unit
is also connected with the detection unit, and is configured to
control the detection unit to stop outputting the sampling control
signals while control the power supply line to be conductive. For
example, the timing circuit module in the detection unit is further
connected with the output terminal of the logic latch circuit
module in the control unit, and when the logic latch circuit module
outputs the latch signals in a high level state, the timing circuit
module does not output the first sampling control signal or the
second sampling control signal, thereby effectively preventing such
problems as mis-power-off of the load caused by unstable voltage of
the AC input power.
[0091] Now, the leakage protection circuit structure as shown in
FIG. 10 is taken as an example to describe the operating process of
the leakage protection circuit. When the load is connected with the
power supply line, the limited voltage detection circuit module 111
acquires the voltage of the power supply line in real time and
outputs the first sampling control signal when the acquired voltage
falls within the predetermined limited voltage range; and the
timing circuit module 112 outputs the second sampling control
signal based on the first sampling control signal and begins to
time the detection timing, wherein the existence duration of the
second sampling control signal is shorter than that of the first
sampling control signal, the sampling unit 12 samples the
electrical signal from the power supply line based on the second
sampling control signal and provides the voltage of the electrical
signals to the comparison circuit module 131 included in the
control unit 13 to compare the voltage of the electrical signals
with the predetermined power-off protection voltage threshold, if
the voltage of the electrical signals is lower than the power-off
protection voltage threshold, it indicates that the voltage of the
AC input power is divided in a man-made manner, the comparison
circuit module 131 outputs a low level signal, and the logic latch
circuit module 132 controls the switch circuit module 133 to cut
off the power supply line based on the low level signal; if the
voltage of the electrical signals is higher than the power-off
protection voltage threshold, it indicates that the voltage of the
AC input power is not divided, the comparison circuit module 131
outputs a high level signal, and the logic latch circuit module 132
outputs the latch signal in a high level state based on the high
level signal and controls the switch circuit module 133 to control
the power supply line in conductive state.
[0092] When the power supply line is in non-conductive state, when
the detection timing is not exceeded, the timing circuit module 112
does not output the second sampling control signal based on the
first sampling control signal, and until detection timing is
exceeded, output the second sampling control signal responds to the
first sampling control signal. In addition, when the power supply
line is in conductive state, the timing circuit module 112 is
controlled not to output the second sampling control signal so as
to disconnect the loop in which the sampling resistor is located,
thereby reducing the power consumption of the leakage protection
circuit.
[0093] The present application further provides a chip containing
the leakage protection circuit, and the chip can be assembled in a
power supply line which supplies power to the load. In some
examples, the chip is assembled in a drive device. For example, the
chip is assembled in a rear terminal of the rectifying circuit in
the drive device. The drive device is an LED drive device as an
example.
[0094] Please refer to FIG. 11 which is a schematic diagram of a
packaging structure of the chip containing the leakage protection
circuit. As shown in the figure, the chip contains multiple pins,
wherein at least one pin is used for being accessed to the power
supply line of the load such that the power supply line via the
chip. The pins include GND, DRAIN and HV pins. Wherein the HV pin
serves as a current input terminal of the chip and is connected to
the power supply line, the DRAIN and GND pins serve as the ground
wire loop of the power supply line and are accessed to the power
supply line such that the power supply line via the chip. The
leakage protection circuit samples the electrical signals from the
power supply line at intervals through detecting the HV pin,
detects the voltage of the sampled electrical signals so as to
determine whether the voltage of the AC input power is divided or
not, and controls the conductive or non-conductive state of the
circuit between the DRAIN and GND pins based on the determined
results, thereby realizing leakage protection. The quantity of the
pins of the chip is related to the integrated circuit module, for
example, the chip contains the leakage protection circuit, the
constant-voltage power supply used by the leakage protection
circuit can be shared with the constant-voltage power supply in
other circuits in the drive device or can be singly configured and
integrated in the chip. For the instance of sharing a
constant-voltage power supply, the chip further includes a pin used
for connecting with the constant-voltage power supply.
[0095] Inside the chip as shown in FIG. 11, the HV, DRAIN and GND
pins are all connected with the leakage protection circuit, wherein
the HV pin is used for providing the voltage of the power supply
line to the leakage protection circuit, and the DRAIN and GND pins
are used for connecting or disconnecting the power supply line
under the control of the leakage protection circuit. The leakage
protection circuit is configured to sample the power supply line at
intervals, determine whether the voltage of the AC input power is
divided or not based on the detection of the voltage of the sampled
electrical signals, and control the conductive state or
non-conductive state of the power supply line based on the
determined result.
[0096] In some other embodiments, based on the actual design
requirements of the peripheral circuit of the chip and other
circuits in the drive device in which the chip is located, the chip
can further include a pin used for outputting the leakage
protection control signal and a pin used for connecting the power
supply line. Wherein the leakage protection control signal is
generated and output when the leakage protection circuit confirms
electric leakage through sampling at intervals and voltage division
detection. Through the pin used for outputting the leakage
protection control signal, other circuits connected with the power
supply line can give corresponding leakage protection response
based on the received leakage protection control signals. Wherein
the other circuits include but are not limited to a filter circuit
and a drive circuit, etc. For example, please refer to FIG. 16
which shows a structural schematic diagram of the leakage
protection circuit and the drive circuit. The leakage protection
circuit 41 is connected with the power supply line and is grounded
via the pin of the chip; the drive chip 42 includes an enable
control unit (not shown in the figure), the controlled terminal
(namely, the enable terminal EN) is connected with the output
terminal of the leakage protection circuit 41 via another pin of
the chip and is connected with the switch device or the logic
circuit (not shown in the figure) in the drive circuit 42, the
enable control unit controls the corresponding switch device or the
logical circuit when receiving the leakage protection control
signal, such that the drive circuit stops providing power supply to
the load until the leakage protection control signal is invalid,
and provides power supply to the load, at this time, the drive
circuit 42 can execute the drive operation. For another example,
please refer to FIG. 17 which shows another structural schematic
diagram of the leakage protection circuit and the drive circuit,
the leakage protection circuit 51 is connected with the power
supply line and is grounded via the pin of the chip; the drive
circuit 52 contains an enable control unit and an existing drive
controller, the controlled terminal of the enable control unit is
connected with the output terminal of the leakage protection
circuit via another pin of the chip, the input terminal is
connected with the power supply terminal of the drive controller,
and the output terminal is grounded; and when the leakage
protection circuit 51 outputs the leakage protection control
signal, the enable control unit gives corresponding leakage
protection response based on the leakage protection control signal,
that is, make the power supply terminal VCC of the drive controller
be grounded, such that the existing drive controller cannot reach
its normal operating voltage.
[0097] Herein, the sampling interval of the leakage protection
circuit can be set based on the voltage change period of the power
supply line. For example, the electrical signals can be sampled at
the voltage peak or the valley in each rectified voltage change
period or in at least every rectified voltage change period, or the
electrical signals can be sampled in the fixed voltage area between
the voltage peak and the valley in each rectified voltage change
period or in at least every rectified voltage change period.
Wherein in order to ensure that human bodies will not be damaged by
continuous electric shock during unintended touch period, the
sampling interval is a millisecond or even a microsecond, for
example, the sampling interval may be every half of a voltage
change period, every one voltage change period or every multiple
voltage change periods. The sampling interval can be realized
through the circuit structure which is designed by utilizing the
voltage change period in the leakage protection circuit. Or, the
sampling interval is set according to the predetermined duration.
For example, the leakage protection circuit contains a capacitor
and a resistor, and the sampling interval is determined based on
the charging duration of the capacitor; wherein the technicians can
design corresponding sampling intervals through assembling a
resistor. The resistor can be an adjustable resistor or a fixed
resistor.
[0098] Herein, in the voltage detection manner of the leakage
protection circuit, the sampled voltage can be compared with the
predetermined reference voltage corresponding to the sampling
instant to determine whether the voltage of the AC input power is
divided or not, so as to determine the conductive or non-conductive
state of the power supply line connected to the load. For example,
when detecting the voltage of the power supply line is zero, the
leakage protection circuit starts the timing of the sampling
interval, samples the electrical signals from the power supply line
when timing reaches, determines the voltage threshold when timing
reaches based on the voltage change period of the power supply
line, and compares the voltage of the sampled electrical signals
with the voltage threshold to determine whether the voltage of the
AC input power is divided or not. When the voltage of the AC input
power is determined to be divided, the leakage protection circuit
can output the leakage protection control signals to control the
other circuits connected with the power supply line to give
corresponding leakage protection response or control the power
supply line to be in non-conductive state.
[0099] In some embodiments, the leakage protection circuit samples
the voltage of the electrical signals based on the sampling
interval set according to the voltage change period, and can
determine whether the voltage of the AC input power is divided or
not by comparing the voltage of the electrical signals with the
predetermined power-off protection voltage threshold. Therefore, as
shown in the FIG. 2, the leakage protection circuit includes: a
detection unit 11, a sampling unit 12 and a control unit 13.
[0100] The detection unit 11 is connected with the power supply
line via an HV pin, and is configured to output sampling control
signals based on the detection of the voltage of the power supply
line. Herein, the detection unit 11 can detect the change of the
voltage of the power supply line in real time, and determine to
reach the sampling interval when detecting that the voltage changes
to the predetermined reference voltage value and output the sampled
control signals. Wherein the predetermined reference voltage value
can also be equal to any voltage value correspond to the voltage
change period, such as the peak value, the valley value and the
intermediate value. The sampling unit performs sampling operations
based on the sampling control signal.
[0101] In some embodiments, the detection unit includes a limited
voltage detection circuit module connected with the power supply
line, and is configured to detect the voltage of the power supply
line, and output the first sampling control signal when the
detected voltage falls within the predetermined limited voltage
range, wherein the limited voltage range is intercepted in the
voltage change range of the power supply line, for example, the
limited voltage range is [V1,V2], wherein 0.ltoreq.V1<V2<V
max, and V max is the maximum value in the voltage change
range.
[0102] In order to realize the above limited voltage detection, the
limited voltage detection circuit module includes at least one
comparator, and the comparator is configured to compare whether the
voltage of the power supply line falls in the predetermined limited
voltage range, wherein the comparator is configured to provide the
boundary threshold of the limited voltage range. The comparator can
be a hysteresis comparator, a window comparator or a zero-crossing
comparator, etc. In some embodiments, the limited voltage detection
circuit module is a valley bottom detection circuit designed based
on the sine wave changes. For example, as shown in FIG. 3, the
limited voltage detection circuit module includes a zero-crossing
comparator, the negative input terminal of the zero-crossing
comparator is accessed to the boundary threshold of the limited
voltage range, the positive input terminal of the zero-crossing
comparator is connected with the power supply line directly or via
a circuit containing a sampling resistor, and when the voltage
change of the power supply line is smaller than the boundary
threshold, the first sampling control signal is output. Wherein the
boundary threshold is greater than zero, such that the first
sampling control signal maintains for an effective duration, and
meanwhile triggering or no triggering by mistake caused by unstable
voltage of the power supply line can be tolerated. The sampling
unit can sample the electrical signals from the power supply line
based on the rising edge or the falling edge of the first sampling
control signal, or can continuously sample the electrical signals
in the effective duration of the first sampling control signal. The
sampling unit can perform the sampling operation once in each
voltage change period based on the first sampling control
signal.
[0103] In still some other embodiments, the detection unit further
includes a timing circuit module. The timing circuit module is
connected with the limited voltage detection circuit module and is
configured to output a second sampling control signal based on the
first sampling control signal, wherein a second sampling control
signal is effective within a time limit. The timing circuit module
outputs the second sampling control signal when the rising edge of
the first sampling control signal is detected, and the sampling
unit samples the electrical signals when the second sampling
control signal is effective. Wherein, the second sampling control
signal is generated from the first sampling control signal, and the
second sampling control signal is effective within a time limit,
which is preset by the timing circuit based on the effective
duration of the first sampling control signal. In addition, the
effective duration of the second sampling control signal is deemed
as the sampling duration allowed by the sampling unit. The limit of
the sampling duration can effectively prevent mis-connectivity
operations caused by jittering of the sampled electrical signals.
For example, with reference to FIG. 4, the timing circuit module
outputs the second sampling control signal when the rising edge of
the first sampling control signal is detected, and times the
existence duration of the second sampling control signal, in the
timing duration, the sampling unit samples the electrical signals.
Wherein in order to prevent mis-connectivity operations caused by
jittering of the sampled electrical signals, the timing circuit
module outputs the second sampling control signal within the
existence duration of the first sampling control signal, namely,
the existence duration of the second sampling control signal is
shorter than the existence duration of the first sampling control
signal. The sampling unit samples the electrical signals based on
the second sampling control signal.
[0104] In some specific examples, the timing circuit module
contains a clock signal generator, a counter 1, a logic device
group and a switch and the like, wherein the switch is on with the
limited voltage detection circuit module, the switch is on with the
control terminal of the counter 1, the input terminal of the
counter 1 is connected with the clock signal generator, and the
output terminal of the counter 1 is connected with the logic device
group, wherein the switch is controlled to be on or off based on
the first sampling control signal, when the switch is on, the
counter 1 begins to count the received clock signals, and before
the number of pulses of the clock signals counted by the counter 1
reaches the predetermined value, the logic device group outputs the
second sampling control signal; and when the number of pulse
signals counted by the counter 1 reaches its count value, the logic
device group is controlled not to output the second sampling
control signal, until the next first sampling control signal
arrives.
[0105] In still some specific examples, as shown in the FIG. 5, the
timing circuit module contains a capacitor, a capacitor charge
controller, a capacitor discharge controller, two comparators, a
logic device group and the like, wherein the capacitor discharge
controller is connected a capacitor in parallel; the control
terminal of the capacitor charge controller receives the first
sampling control signal, the input terminal is accessed to a
constant voltage, and the output terminal is connected to a
capacitor; one end of the capacitor is grounded directly or via a
resistor; the another end of capacitor is also connected to the
negative input terminal comparators A1 and A2; wherein another
positive input terminal of the comparator A1 is accessed to the
reference voltage Vref 1, while another positive input terminal of
the comparator A2 is accessed to the reference voltage Vref 2; the
output terminal of the comparators A1 and A2 are both connected
with the logic device group, and the logic device group outputs the
second sampling control signal, wherein the capacitor charge
controller and the capacitor discharge controller can both be a
controlled switch, such as an MOSFET. The reference voltage Vref 1
approaches 0V, while Vref 2 is a voltage value greater than Vref 1.
Through the design of the technicians, the duration of the
capacitor voltage rising from Vref 1 to Vref 2 is shorter than the
existence duration of the first sampling control signal. In the
initial period, the capacitor discharge controller is short
connected to a capacitor and the capacitor charge controller is
disconnected, such that the capacitor is in a zero charge state,
correspondingly, the comparator A1 outputs the low level; when the
capacitor charge controller receives the first sampling control
signal, the capacitor charge controller is conductive and the
capacitor discharge controller is non-conductive, such that the
capacitor is charged, when the capacitor voltage is higher than the
reference voltage Vref 1, the comparator A1 outputs the high level
while the comparator A2 still outputs the low level, and when the
comparator A1 outputs the high level while the comparator A2
outputs the low level, the logic device group outputs the second
sampling control signal based on the predetermined logic
configuration; the capacitor continues to be charged, such that
when the voltage of the capacitor reaches the Vref 2, the
comparator A2 jumps to the high level, and when the comparators A1
and A2 both output the high level, based on the logic
configuration, the logic device group will not output the second
sampling control signal, and controls the capacitor charge
controller to be off so that the capacitor is not charged, and
controls the capacitor discharge controller to be on so as to
discharge the electric charge of the capacitor, until the next
first sampling control signal arrives.
[0106] In some embodiments, the timing circuit module further sets
the detection timing based on the first sampling control signal,
and outputs the second sampling control signal after the detection
timing is exceeded. Please refer to FIG. 6 which is a waveform
schematic diagram of the relationship between the second sampling
control signal output by the timing circuit module and the first
sampling control signal. As shown in the figure, wherein the
detection timing can enable that, within at least in one time
interval T2 of first sampling control signal, the timing circuit
module does not output the second sampling control signal based on
the first sampling control signal. Therefore, the existence
duration of the detection timing is the minimum time interval of
the second sample control signal, and the timing circuit module can
output the second sampling control signal in the case that the
detection timing is exceeded and the first sampling control signal
is effective, that is, the timing circuit module can output the
second sampling control signal based on the first sample control
signal only if the minimum time interval is satisfied. Further, the
sampling interval may be set based on the change period of the
voltage of the power supply line or based on a predetermined
duration, the minimum time interval also may be set based on the
change period of the voltage of the power supply line or based on a
predetermined duration.
[0107] Based on the technical concept mentioned above, the timing
circuit module may further set a sampling interval T3, during which
the limited voltage detection circuit module detects a voltage of
the power supply line and outputs a first sampling control signal
when the detected voltage falls within a predetermined limited
voltage range. For example, the timing circuit module is configured
to start the sampling interval T3 after T2 is exceeded, instruct
the limited voltage detection circuit module to detect the voltage
of the power supply line within T3, and output a first sampling
control signal when the detected voltage falls within a
predetermined limited voltage range. The timing circuit module is
configured to output a second sampling control signal based on the
received first sampling control signal, and start the time T2 and
perform loop operation.
[0108] In some specific examples, the timing circuit module
contains multiple counters, wherein one counter 1 is used for
counting the existence duration of the second sampling control
signal, while the other counter 2 is used for counting the
detection timing. The timing circuit module further includes a
clock signal generator, a switch and a logic device group. The
switch is controlled to be on or off based on the first sampling
control signal, when the switch is on, the counter 1 begins to
count the received clock signals, and before the number of pulses
of the clock signals counted by the counter 1 reaches the
predetermined value, the logic device group outputs the second
sampling control signal; and when the number of pulse signals
counted by the counter 1 reaches its count value, the logic device
group is controlled not to output the second sampling control
signal, at this time, the counter 2 begins to count the number of
pulses of the received clock signals; when the counter 2 reaches
its count value, namely, the detection timing is exceeded, the
logic device group is controlled to output the second sampling
control signal.
[0109] In still some other specific examples, as shown in the FIG.
7, the timing circuit module can contain multiple capacitors, and
each capacitor is configured with a capacitor charge controller and
a capacitor discharge controller, multiple comparators and a logic
device group, etc. Wherein the configured capacitor discharge
controller is connected to a corresponding capacitor in parallel;
the control terminal of the configured capacitor charge controller
receives the first sampling control signal, the input terminal is
accessed to a constant voltage and the output terminal is connected
with a corresponding capacitor; one end of each of the capacitors
is grounded directly or via a resistor; another end of the
capacitors C1 is further connected with the negative input terminal
of the comparators A1 and A2; wherein the positive input terminal
of the comparator A1 is accessed to the reference voltage Vref 1,
the positive input terminal of the comparator A2 is accessed to the
reference voltage Vref 2; the negative input terminal of comparator
A3 is connected with another capacitor C2 and the positive input
terminal is accessed to the reference voltage Vref 3; the output
terminal of the comparators A1, A2 and A3 are all connected with
the logic device group, and the logic device group outputs the
second sampling control signal, wherein the reference voltage Vref
1 approaches 0V, and Vref 2 is a voltage value greater than Vref 1.
Through the design of the technicians, the duration of the voltage
of the capacitor C1 rising from Vref 1 to Vref 2 is shorter than
the existence duration of the first sampling control signal; and
the duration of the voltage of the capacitor C2 from the initial
value (such as 0V) to Vref 3 is longer than the existence duration
of a first sampling control signal. In the initial period, the
capacitor discharge controller CDC1 is short connected to the
capacitor C1 and the capacitor charge controller CCC1 is off, such
that the capacitor C1 is in a zero charge state, meanwhile, the
capacitor discharge controller CDC2 connected with the capacitor C2
is off and the capacitor charge controller CCC2 is on, such that
the capacitor C2 is in a charge saving state; correspondingly, the
comparators A1 and A2 output the low level while the comparator A3
outputs the high level; when the capacitor charge controller CCC1
connected with the capacitor C1 receives the first sampling control
signal, the capacitor charge controller CCC1 connected with the
capacitor C1 is on and the capacitor discharge controller CDC1 is
off, such that the capacitor C1 is charged. When the voltage of the
capacitor C1 is higher than the reference voltage Vref 1, the
comparator A1 outputs the high level and the comparator A2 still
outputs the low level, and when the comparators A1 and A3 output
the high level and the comparator A2 outputs the low level, the
logic device group outputs the second sampling control signal based
on the predetermined logic configuration; at this time, the
capacitor discharge controller CDC2 and the capacitor charge
controller CCC2 enable the capacitor C2 to discharge based on the
second sampling control signal, and the comparator A3 outputs the
low level; however, the capacitor C1 continues to be charged, such
that when the voltage reaches Vref 2, the comparator A2 jumps to
the high level, and when the comparators A1 and A2 both output the
high level and the comparator A3 outputs the low level, based on
the logic configuration, the logic device group does not output the
second sampling control signal, controls the capacitor charge
controller CCC1 to be off such that the capacitor C1 is not
charged, and controls the capacitor discharge controller CDC1 to be
on to discharge the charge of the capacitor C1. When the capacitor
C1 is discharged, the capacitor charge controller CCC2 of the
capacitor C2 is on and the capacitor discharge controller CDC2 is
off such that the capacitor C2 is charged, until the voltage of the
capacitor C2 reaches Vref 3, then the comparator A3 outputs the
high level, and when the comparator A3 outputs the high level,
based on the logic configuration, the logic device group outputs
the second sampling control signal based on the change of the level
of the comparators A1 and A2.
[0110] It should be noted that, the circuit structure of the timing
circuit module mentioned above is only exemplary, rather than
limiting the circuit structure of the timing circuit module in the
present application. In fact, based on the design of the timing
logic by the technicians, other timing circuit modules including a
comparator, a logic device group and a capacitor can also be
proposed; or, the timing circuit module containing a clock signal
generator and a counter can also be proposed, which are not
elaborated herein, however, the timing circuit module designed
based on the technical enlightment of the above timing circuit
module should be deemed as the specific example of the present
application. In addition, the devices in the above timing circuit
module can be included in the chip. To facilitate the periods of
various ACs provided by different AC input powers, the devices used
for timing, such as a capacitor and the peripheral devices or a
counter, in the timing circuit module can be assembled outside the
chip, and the devices can be controlled to acquire data through
corresponding pins, such that the technicians can select based on
the requirements of specific designs. Based on the design of the
above timing circuit modules, one example is as follows: the
sampling unit included in the leakage protection circuit samples
the voltage of the electrical signals from the power supply line
during the period in which the second sampling control signal is
received.
[0111] It should also be noted that, as required by actual logic
design, the logic device group mentioned in any of the above
examples can contain at least one logic device, and all the logic
devices are electrically connected to realize corresponding logic
configuration, wherein the logic devices include but are not
limited to an AND gate, an OR gate, a NAND gate, a NOT gate, an
encoder, a decoder, a selector, etc.
[0112] The sampling unit is connected with the detection unit and
is configured to sample the electrical signals from the power
supply line based on the received sampling control signals.
[0113] Please refer to FIG. 8 which is a structural schematic
diagram of the leakage protection circuit in one embodiment. As
shown in the figure, wherein the sampling unit 12 contains a
controlled switch and a sampling resistor, wherein the control
terminal of the controlled switch is connected with the output
terminal of the detection unit, one access terminal of the
controlled switch is connected with the power supply line via the
HV pin, while the other access terminal is grounded (namely,
connected to the GND pin) via the sampling resistor, and the
sampling resistor is further connected with the control unit 13.
Wherein the controlled switch includes but is not limited to any
one of a triode (BJT), a junction field effect transistor (JFET), a
depletion MOSFET and thyristor. When the detection unit 11 outputs
a sampling control signal, the controlled switch is on, and the
control unit 13 acquires the voltage of the sampled electrical
signals from the sampling resistor.
[0114] In one specific example, as shown in FIG. 8, the controlled
switch is an MOSFET as an example, the gate of the MOSFET is
connected with the output terminal of the detection unit, while the
drain of the MOSFET is connected with the power supply line and the
source is connected with the sampling resistor. Wherein based on
the detection unit described above, the MOSFET is on when receiving
the first sampling control signal or the second sampling control
signal, such that the control unit 13 acquires the sampled voltage
of the electrical signals from the power supply line.
[0115] The control unit is configured to compare the voltage of the
sampled electrical signals with the predetermined power-off
protection voltage threshold and providing leakage protection based
on the compared results.
[0116] Herein, the power-off protection voltage threshold
predetermined by the control unit can be supplied by a constant
voltage circuit. The power-off protection voltage threshold can be
designed based on the fact that the value of voltage drop of the
sampling unit will be influenced by the division of the AC input
power by human bodies. When the control unit determines that the
sampled voltage is lower than the power-off protection voltage
threshold, the power supply line may be controlled to be in
non-conductive state or the leakage protection control signals may
be output; otherwise, the power supply line is in conductive state
so as to enable the load to operate normally.
[0117] In one embodiment, the control unit contains a comparison
circuit module, a logic latch circuit module and a switch circuit
module, wherein the comparison circuit module is configured to
compare the voltage of the sampled electrical signals with the
predetermined power-off protection voltage threshold and output the
compared results. The logic latch circuit module is connected with
the comparison circuit module and is configured to latch the
compared results. The switch circuit module is connected with the
logic latch circuit module and is configured to control the
conductive state or non-conductive state of the power supply line
based on the latch signals.
[0118] Please refer to FIG. 9 which shows a waveform schematic
diagram of the voltage of sampled electrical signals received by
the comparison circuit module when voltage division is generated at
the AC input power side due to man-made misoperation and when the
load is connected to the power supply line normally with no
man-made voltage division, corresponding to the leakage protection
circuit as shown in FIG. 8. As shown in the figure, when the load
is connected to the power supply line with no man-made
misoperation, the sampled voltage is higher than the power-off
protection voltage threshold Vref; when the load is connected to
the power supply line with man-made misoperation, the sampled
voltage is lower than the power-off protection voltage threshold
Vref due to voltage division by human bodies. When the sampled
voltage is higher than the power-off protection voltage threshold
Vref, the comparison circuit module outputs a jumping signal, the
logic latch circuit module latches the jumping signal and outputs
the latch signal to a switch circuit module, and the switch circuit
module controls the power supply line to be in conductive state,
otherwise, the comparison circuit module does not output a jumping
signal, the logic latch circuit module does not output latch
signals, and the switch circuit module maintains the non-conductive
state of the power supply line, thereby protecting the safety of
the load and human.
[0119] In a specific example, the comparison circuit module
includes a comparator, and the switch circuit module includes the
controlled switch and a switch drive module, the negative input
terminal of the comparator is accessed to the power-off protection
voltage threshold and the positive input terminal of the comparator
is connected to the sampling unit to get the voltage of the sampled
electrical signals, the output terminal of the comparator is
connected to the input terminal of the logic latch circuit, and the
output terminal of the logic latch circuit module is connected to
the switch drive module. The switch circuit module includes a gate
drive module and an MOSFET as an example, the gate of the MOSFET is
connected with the output terminal of the logic latch circuit
through the gate drive module, and the source and the drain are
connected with the two ends of the power supply line, that is, the
MOSFET is a necessary part of the power supply line, the current
flow through the MOSFET. When there is no voltage division is
generated at the AC input power side, the comparator always outputs
the high level, and the MOSFET is turned on and the power supply
line is in conductive state such that the load works normally. In
another embodiment, the gate of the MOSFET is connected with the
output terminal of the comparator through the gate drive module and
the like. Please refer to FIG. 10 which is a structural schematic
diagram of the leakage protection circuit in another embodiment,
wherein the logic latch circuit module latches a high level state
when the comparison circuit module outputs the jump signal from a
low level to a high level, and latches a low level state when the
comparison circuit module outputs the jump signal from a high level
to a low level. In the initial period, the logic latch circuit
module is in a low level state, and the switch circuit module cuts
off the power supply line based on the received latch signals in a
low level state; and when the comparison circuit module outputs the
jump signal from a low level to a high level, the logic latch
circuit module latches the high level state and outputs the latch
signals in a high level state, then the switch circuit module is on
such that the power supply line is in conductive state. Therefore,
it can be seen that the latch signal is representing the leakage
protection control signal generated by the leakage protection
circuit.
[0120] Herein, the MOSFET in the controlled switch can also be
substituted into any one of a triode (BJT), a junction field effect
transistor (JFET), a depletion MOSFET and a thyristor. The switch
drive module is not necessarily a gate drive module, but can be
adjusted based on the actual design requirements. For example, the
switch circuit module includes an MOSFET and a source drive module,
etc.
[0121] In some other embodiments, the output terminal of the logic
latch circuit module is connected with the other circuits (such as
the drive circuit described above) connected with the power supply
line, such that the other circuits provide corresponding leakage
protection based on the latch signals, and this will not be
repeated redundantly herein.
[0122] It should be noted that, the comparative relationship
between the voltage of the sampled electrical signal with voltage
division by human bodies and the power-off protection voltage
threshold and the comparative relationship between the sampled
electrical signal voltage with no voltage division by human bodies
and the power-off protection voltage threshold as shown in the
above FIG. 9 are related to the circuit structure of the sampling
unit. When the circuit structure of the sampling unit is configured
in such a way that the voltage of the sampled electrical signals
with voltage division by human bodies is higher than the voltage of
the sampled electrical signals with no voltage division by human
bodies, the corresponding control unit should provide corresponding
leakage protection based on the compared results contrary to those
shown in FIG. 9. Wherein the circuit structure of the sampling unit
can also be of a connection manner in which one access terminal of
the controlled switch is connected to the power supply line via a
sampling resistor while the other access terminal of the controlled
switch is grounded, and the connection manners will not be
enumerated herein.
[0123] In order to prevent the logic latch circuit module from
providing wrong latch signals in the restarting operation after
users turn off the electrical appliance, when the power supply for
the load is interrupted, the logic latch circuit module needs to
reset to the initial low level state. In some specific examples,
the logic latch circuit module resets based on the fact that the
leakage protection circuit is in an undervoltage state.
[0124] Wherein the undervoltage state is a state in which the
voltage of the load cannot reach its normal working voltage due to
the influence of external factors or electrical appliance
components connected with or located on the power supply line in
the normal operating period of the load, such that the load is in a
state of not operating. The undervoltage state of the leakage
protection circuit is caused by man-made power failure or by
abnormity of the electrical appliance components inside (or
outside) the leakage protection circuit. For example, the instances
enabling the leakage protection circuit to be in an undervoltage
state include but are not limited to the power-off state of the
leakage protection circuit in the power off period and the state of
the leakage protection circuit when the power supply system cannot
provide corresponding operating voltage to the active device in the
leakage protection circuit.
[0125] The logic circuit module can reset the latched signals
through detecting the undervoltage state of the leakage protection
circuit. In one specific example, the reset terminal of the logic
latch circuit module is connected with a power supply line, when
the power supply of the power supply line is interrupted, the
leakage protection circuit is in an undervoltage state, and the
reset terminal of the logic circuit module receives effective reset
signals. In another specific example, the reset terminal of the
logic latch circuit module is connected with the undervoltage
protection circuit used for protecting the leakage protection
circuit, and when the undervoltage protection circuit generates
undervoltage protection signals due to the detection of an
undervoltage state of the leakage protection circuit, the reset
terminal of the logic latch circuit module takes the undervoltage
protection signal as the effective reset signal, thereby realizing
the reset operation of the logic latch circuit module.
[0126] In addition, due to the logic latch circuit module, when the
power supply line is in conductive state, the detection unit and
the sampling unit are not necessarily required to continuously
provide voltage of the electrical signals to continuously control
the on or off state of the switch circuit unit. Therefore, the
sampling of the power supply line at intervals is stopped when the
power supply line is controlled to be conductive. Wherein the
leakage protection circuit can add a control circuit module in the
detection unit or a sampling unit to correspondingly stop the
detection or sampling. In some specific examples, the control unit
is also connected with the detection unit, and is configured to
control the detection unit to stop outputting the sampling control
signals while control the power supply line to be conductive. For
example, the timing circuit module in the detection unit is further
connected with the output terminal of the logic latch circuit
module in the control unit, and when the logic latch circuit module
outputs the latch signals in a high level state, the timing circuit
module does not output the first sampling control signal or the
second sampling control signal, thereby effectively preventing such
problems as mis-power-off of the load caused by unstable voltage of
the AC input power.
[0127] Now, the leakage protection circuit structure shown in FIG.
10 and the chip packaging structure shown in FIG. 11 are taken as
an example to describe the operating process of the chip. When the
load is connected with a power supply line, the HV pin is
electrically connected with the power supply line, the limited
voltage detection circuit module 111 connected with the HV pin and
inside the chip can acquire the voltage of the power supply line in
real time and outputs the first sampling control signal when the
acquired voltage falls within the predetermined limited voltage
range; and the timing circuit module 112 outputs the second
sampling control signal based on the first sampling control signal
and begins to time the detection timing, wherein the existence
duration of the second sampling control signal is shorter than that
of the first sampling control signal, the sampling unit 12 samples
the electrical signal from the power supply line based on the
second sampling control signal and provides the voltage of the
electrical signals to the comparison circuit module 131 included in
the control unit 13 to compare the voltage of the electrical
signals with the predetermined power-off protection voltage
threshold, if the voltage of the electrical signals is lower than
the power-off protection voltage threshold, it indicates that the
voltage of the AC input power is divided in a man-made manner, the
comparison circuit module 131 outputs a low level signal, and the
logic latch circuit module 132 controls the switch circuit module
to cut off the power supply line based on the low level signal; if
the voltage of the electrical signals is higher than the power-off
protection voltage threshold, it indicates that no man-made
electric shock occurs, the comparison circuit module 131 outputs a
high level signal, and the logic latch circuit module 132 outputs
the latch signal in a high level state based on the high level
signal and controls the switch circuit module 133 to be
communicated with DRAIN pin and the GND pin, such that the power
supply line in conductive state.
[0128] When the power supply line is in non-conductive state, when
the detection timing is not exceeded, the timing circuit module 112
does not output the second sampling control signal based on the
first sampling control signal, and until detection timing is
exceeded, output the second sampling control signal responds to the
first sampling control signal. In addition, when the power supply
line is in conductive state, the timing circuit module 112 is
controlled not to output the second sampling control signal so as
to disconnect the loop in which the sampling resistor is located,
thereby reducing the power consumption of the leakage protection
circuit.
[0129] The present application further provides a drive device. The
drive device is configured to provide DC power supply higher than
body safety voltage to the load. With the LED load as an example,
as an LED drive device, the drive device is configured to drive the
LED load to operate normally. Herein, the LED load takes the LED
tube lamp as an example, when the LED tube lamp is installed,
people may touch the needle-shaped pin due to misoperation, when
the needle-shaped pin is connected with the LED drive device at the
same time, human bodies will be damaged by electric shock. To this
end, a leakage protection circuit is assembled in the LED drive
device. The drive device provided by the present application can be
used as an LED drive device and can be assembled in the AC input
power and provide a power supply line to the LED load.
[0130] FIG. 12 shows a frame structural schematic diagram of a
drive device. As shown in the figure, the drive device includes a
rectifying circuit 21, a leakage protection circuit 22 and a drive
circuit 23. The drive device is configured to supply the DC power
supply higher than the body safety voltage to the load 24. Wherein
with the LED load as an example, the drive device is an LED drive
device and provides leakage protection to the user and the LED load
when the LED load is connected to the power supply line. The drive
device provides leakage protection when detecting the voltage
division generated by man-made misoperation and maintain the power
supply line in conductive state and provides power supply to the
LED load when detecting no man-made misoperation.
[0131] The rectifying circuit 21 is configured to rectify the
accessed AC and provide the rectified voltage to the power supply
line of the load. Herein, the rectifying circuit 21 is accessed to
the AC input power and is subjected to rectified output via a
rectifier bridge constituted by four diodes.
[0132] The leakage protection circuit 22 is connected to the
rectifying circuit 21 and is configured to sample the power supply
line at intervals, detect the voltage of the sampled electrical
signals to determine whether the voltage of the AC input power is
divided, and provide leakage protection based on the determined
results.
[0133] As shown in FIG. 12, the leakage protection circuit 22 is
coupled to rectifying circuit 21. The leakage protection circuit
can be integrated into a chip. In some embodiments, as shown in
FIG. 11, the HV pin of the chip is connected with the output of the
rectifier circuit, the GND pin is connected with the grounded end
of the rectifier bridge, and the DRAIN pin of the chip is connected
onto the loop of the power supply line of the load. Therefore, the
conductive or non-conductive state of the grounded part in the
power supply line of the load is controlled by the leakage
protection circuit, namely, when the leakage protection circuit
detects that the voltage of the AC input power is divided, the
power supply line is cut off, otherwise, the power supply line is
in conductive state. The quantity of the pins of the chip is
related to the integrated circuit module. For example, the chip
contains the leakage protection circuit, the constant voltage power
supply used by the leakage protection circuit can be shared by
other circuits in the drive device or can be singly assembled and
integrated in a chip. For the instance of sharing a constant
voltage power supply, the chip further includes a pin used for
connecting the constant voltage power supply.
[0134] In some other embodiments, based on the actual design
requirements of the peripheral circuit of the chip and other
circuits in the drive device in which the chip is located, the chip
can further include a pin used for outputting the leakage
protection control signal and a pin used for connecting the power
supply line. Wherein the leakage protection control signal is
generated and output when the leakage protection circuit confirms
electric leakage through sampling at intervals and voltage division
detection. Through the pin used for outputting the leakage
protection control signal, other circuits connected with the power
supply line can give corresponding leakage protection response
based on the received leakage protection control signals. Wherein
the other circuits include but are not limited to a filter circuit
and a drive circuit, etc. For example, please refer to FIG. 16
which shows a structural schematic diagram of the leakage
protection circuit and the drive circuit. The leakage protection
circuit 41 is connected with the power supply line and is grounded
via the pin of the chip; the drive chip 42 includes an enable
control unit (not shown in the figure), the controlled terminal
(namely, the enable terminal EN) is connected with the output
terminal of the leakage protection circuit 41 via another pin of
the chip, and the enable control unit controls the switch device or
the logic circuit (not shown in the figure) in the drive circuit
42, the enable control unit controls the switch device or the
logical circuit in the drive circuit 42 when receiving the leakage
protection control signal, such that the energy converted by the
drive circuit 42 can not be provided to the load until the leakage
protection control signal is invalid, and the switch device is
switched into a conductive state, at this time, the drive circuit
42 can execute the drive operation. For another example, please
refer to FIG. 17 which shows another structural schematic diagram
of the leakage protection circuit and the drive circuit, the
leakage protection circuit 51 is connected with the power supply
line and is grounded via the pin of the chip; the drive circuit 52
contains an enable control unit and an existing circuit in the
drive controller, the controlled terminal of the enable control
unit is connected with the output terminal of the leakage
protection circuit via another pin of the chip, the input terminal
is connected with the power supply terminal of the drive chip, and
the output terminal is grounded; and when the leakage protection
circuit 51 outputs the leakage protection control signal, the
enable control unit gives corresponding leakage protection response
based on the leakage protection control signal, that is, make the
power supply terminal VCC of the drive controller be grounded, such
that the active device in the circuit in existing drive controller
cannot reach its normal operating voltage.
[0135] Herein, the sampling interval of the leakage protection
circuit can be set based on the voltage change period of the power
supply line. The sampling interval can be realized through the
circuit structure in the detection unit configured to control the
sampling interval in the leakage protection circuit. For example,
the electrical signals can be sampled at the voltage peak or the
valley in each rectified voltage change period or in at least every
rectified voltage change period, or the electrical signals can be
sampled in the fixed voltage area between the voltage peak and the
valley in each rectified voltage change period or in at least every
rectified voltage change period. Wherein in order to ensure that
human bodies will not be damaged by continuous electric shock
during unintended touch period, the sampling interval is a
millisecond or even a microsecond, for example, the sampling
interval may be every half of a voltage change period, every one
voltage change period or every multiple voltage change periods. The
sampling interval can be realized through the circuit structure
which is designed by utilizing the voltage change period in the
leakage protection circuit. Or, the sampling interval is set
according to the predetermined duration. For example, the leakage
protection circuit contains a capacitor and a resistor, and the
sampling interval is determined based on the charging duration of
the capacitor; wherein the technicians can design corresponding
sampling intervals through assembling a resistor. The resistor can
be an adjustable resistor or a fixed resistor.
[0136] Herein, in the voltage detection manner of the leakage
protection circuit, the sampled voltage can be compared with the
predetermined reference voltage corresponding to the sampling
instant to determine whether the voltage of the AC input power is
divided or not, so as to determine the conductive or non-conductive
state of the power supply line connected to the load. For example,
when detecting the voltage of the power supply line is zero, the
leakage protection circuit starts the timing of the sampling
interval, samples the electrical signals from the power supply line
when timing reaches, determines the voltage threshold when timing
reaches based on the voltage change period of the power supply
line, and compares the voltage of the sampled electrical signals
with the voltage threshold to determine whether the voltage of the
AC input power is divided or not. When the voltage of the AC input
power is determined to be divided, the leakage protection circuit
can output the leakage protection control signals to control the
other circuits connected with the power supply line to give
corresponding leakage protection response or control the power
supply line to be in non-conductive state.
[0137] In some embodiments, the leakage protection circuit samples
the voltage of the electrical signals based on the sampling
interval set according to the voltage change period, and can
determine whether the voltage of the AC input power is divided or
not by comparing the voltage of the electrical signals with the
predetermined power-off protection voltage threshold. Therefore, as
shown in the FIG. 2, the leakage protection circuit includes: a
detection unit 11, a sampling unit 12 and a control unit 13.
[0138] The detection unit 11 is connected with the power supply
line, and is configured to output sampling control signals based on
the detection of the voltage of the power supply line. Herein, the
detection unit 11 can detect the change of the voltage of the power
supply line in real time, and determine to reach the sampling
interval when detecting that the voltage changes to the
predetermined reference voltage value and output the sampled
control signals. Wherein the predetermined reference voltage value
can also be equal to any voltage value correspond to the voltage
change period, such as the peak value, the valley value and the
intermediate value. The sampling unit performs sampling operations
based on the sampling control signal.
[0139] In some embodiments, the detection unit includes a limited
voltage detection circuit module connected with the power supply
line, and is configured to detect the voltage of the power supply
line, and output the first sampling control signal when the
detected voltage falls within the predetermined limited voltage
range, wherein the limited voltage range is intercepted in the
voltage change range of the power supply line, for example, the
limited voltage range is [V1,V2], wherein 0.ltoreq.V1<V2<V
max, and V max is the maximum value in the voltage change
range.
[0140] In order to realize the above limited voltage detection, the
limited voltage detection circuit module includes at least one
comparator, and the comparator is configured to compare whether the
voltage of the power supply line falls in the predetermined limited
voltage range, wherein the comparator is configured to provide the
boundary threshold of the limited voltage range. The comparator can
be a hysteresis comparator, a window comparator or a zero-crossing
comparator, etc. In some embodiments, the limited voltage detection
circuit module is a valley bottom detection circuit designed based
on the sine wave changes. For example, as shown in FIG. 3, the
limited voltage detection circuit module includes a zero-crossing
comparator, the negative input terminal of the zero-crossing
comparator is accessed to the boundary threshold of the limited
voltage range, the positive input terminal of the zero-crossing
comparator is connected with the power supply line directly or via
a circuit containing a sampling resistor, and when the voltage
change of the power supply line is smaller than the boundary
threshold, the first sampling control signal is output. Wherein the
boundary threshold is greater than zero, such that the first
sampling control signal maintains for an effective duration, and
meanwhile triggering or no triggering by mistake caused by unstable
voltage of the power supply line can be tolerated. The sampling
unit can sample the electrical signals from the power supply line
based on the rising edge or the falling edge of the first sampling
control signal, or can continuously sample the electrical signals
in the effective duration of the first sampling control signal. The
sampling unit can perform the sampling operation once in each
voltage change period based on the first sampling control
signal.
[0141] In still some other embodiments, the detection unit further
includes a timing circuit module. The timing circuit module is
connected with the limited voltage detection circuit module and is
configured to output a second sampling control signal based on the
first sampling control signal, wherein a second sampling control
signal is effective within a time limit. The timing circuit module
outputs the second sampling control signal when the rising edge of
the first sampling control signal is detected, and the sampling
unit samples the electrical signals when the second sampling
control signal is effective. Wherein, the second sampling control
signal is generated from the first sampling control signal, and the
second sampling control signal is effective within a time limit,
which is preset by the timing circuit based on the effective
duration of the first sampling control signal. In addition, the
effective duration of the second sampling control signal is deemed
as the sampling duration allowed by the sampling unit. The limit of
the sampling duration can effectively prevent mis-connectivity
operations caused by jittering of the sampled electrical signals.
For example, with reference to FIG. 4 which is a timing sequence
schematic diagram of the limited voltage detection circuit module
and the timing circuit module represented by respectively utilizing
the waveforms of the first sampling control signal and the second
sampling control signal, the timing circuit module outputs the
second sampling control signal when the rising edge of the first
sampling control signal is detected, and times the existence
duration of the second sampling control signal, in the timing
duration, the sampling unit samples the electrical signals. Wherein
in order to prevent mis-connectivity operations caused by jittering
of the sampled electrical signals, the timing circuit module
outputs the second sampling control signal within the existence
duration of the first sampling control signal, namely, the
existence duration of the second sampling control signal is shorter
than the existence duration of the first sampling control signal.
The sampling unit samples the electrical signals based on the
second sampling control signal.
[0142] In some specific examples, the timing circuit module
contains a clock signal generator, a counter 1, a logic device
group and a switch and the like, wherein the switch is on with the
limited voltage detection circuit module, the switch is on with the
control terminal of the counter 1, the input terminal of the
counter 1 is connected with the clock signal generator, and the
output terminal of the counter 1 is connected with the logic device
group, wherein the switch is controlled to be on or off based on
the first sampling control signal, when the switch is on, the
counter 1 begins to count the received clock signals, and before
the number of pulses of the clock signals counted by the counter 1
reaches the predetermined value, the logic device group outputs the
second sampling control signal; and when the number of pulse
signals counted by the counter 1 reaches its count value, the logic
device group is controlled not to output the second sampling
control signal, until the next first sampling control signal
arrives.
[0143] In still some specific examples, as shown in the FIG. 5, the
timing circuit module contains a capacitor, a capacitor charge
controller, a capacitor discharge controller, two comparators, a
logic device group and the like, wherein the capacitor discharge
controller is connected a capacitor in parallel; the control
terminal of the capacitor charge controller receives the first
sampling control signal, the input terminal is accessed to a
constant voltage, and the output terminal is connected to a
capacitor; one end of the capacitor is grounded directly or via a
resistor; the another end of capacitor is also connected to the
negative input terminal comparators A1 and A2; wherein another
positive input terminal of the comparator A1 is accessed to the
reference voltage Vref 1, while another positive input terminal of
the comparator A2 is accessed to the reference voltage Vref 2; the
output terminal of the comparators A1 and A2 are both connected
with the logic device group, and the logic device group outputs the
second sampling control signal, wherein the capacitor charge
controller and the capacitor discharge controller can both be a
controlled switch, such as an MOSFET. The reference voltage Vref 1
approaches 0V, while Vref 2 is a voltage value greater than Vref 1.
Through the design of the technicians, the duration of the
capacitor voltage rising from Vref 1 to Vref 2 is shorter than the
existence duration of the first sampling control signal. In the
initial period, the capacitor discharge controller is short
connected to a capacitor and the capacitor charge controller is
disconnected, such that the capacitor is in a zero charge state,
correspondingly, the comparator A1 outputs the low level; when the
capacitor charge controller receives the first sampling control
signal, the capacitor charge controller is conductive and the
capacitor discharge controller is non-conductive, such that the
capacitor is charged, when the capacitor voltage is higher than the
reference voltage Vref 1, the comparator A1 outputs the high level
while the comparator A2 still outputs the low level, and when the
comparator A1 outputs the high level while the comparator A2
outputs the low level, the logic device group outputs the second
sampling control signal based on the predetermined logic
configuration; the capacitor continues to be charged, such that
when the voltage of the capacitor reaches the Vref 2, the
comparator A2 jumps to the high level, and when the comparators A1
and A2 both output the high level, based on the logic
configuration, the logic device group will not output the second
sampling control signal, and controls the capacitor charge
controller to be off so that the capacitor is not charged, and
controls the capacitor discharge controller to be on so as to
discharge the electric charge of the capacitor, until the next
first sampling control signal arrives.
[0144] In still some other embodiments, the timing circuit module
further sets the detection timing based on the first sampling
control signal, and outputs the second sampling control signal
after the detection timing is exceeded. Please refer to FIG. 6
which is a waveform schematic diagram of the relationship between
the second sampling control signal output by the timing circuit
module and the first sampling control signal. As shown in the
figure, wherein the detection timing can enable that, within at
least in one time interval T2 of first sampling control signal, the
timing circuit module does not output the second sampling control
signal based on the first sampling control signal. Therefore, the
existence duration of the detection timing is the minimum time
interval of the second sample control signal, and the timing
circuit module can output the second sampling control signal in the
case that the detection timing is exceeded and the first sampling
control signal is effective, that is, the timing circuit module can
output the second sampling control signal based on the first sample
control signal only if the minimum time interval is satisfied.
Further, the sampling interval may be set based on the change
period of the voltage of the power supply line or based on a
predetermined duration, the minimum time interval also may be set
based on the change period of the voltage of the power supply line
or based on a predetermined duration.
[0145] Based on the technical concept mentioned above, the timing
circuit module may further set a sampling interval T3, during which
the limited voltage detection circuit module detects a voltage of
the power supply line and outputs a first sampling control signal
when the detected voltage falls within a predetermined limited
voltage range. For example, the timing circuit module is configured
to start the sampling interval T3 after T2 is exceeded, instruct
the limited voltage detection circuit module to detect the voltage
of the power supply line within T3, and output a first sampling
control signal when the detected voltage falls within a
predetermined limited voltage range. The timing circuit module is
configured to output a second sampling control signal based on the
received first sampling control signal, and start the time T2 and
perform loop operation.
[0146] In some specific examples, the timing circuit module
contains multiple counters, wherein one counter 1 is used for
counting the existence duration of the second sampling control
signal, while the other counter 2 is used for counting the
detection timing. The timing circuit module further includes a
clock signal generator, a switch and a logic device group. The
switch is controlled to be on or off based on the first sampling
control signal, when the switch is on, the counter 1 begins to
count the received clock signals, and before the number of pulses
of the clock signals counted by the counter 1 reaches the
predetermined value, the logic device group outputs the second
sampling control signal; and when the number of pulse signals
counted by the counter 1 reaches its count value, the logic device
group is controlled not to output the second sampling control
signal, at this time, the counter 2 begins to count the number of
pulses of the received clock signals; when the counter 2 reaches
its count value, namely, the detection timing is exceeded, the
logic device group is controlled to output the second sampling
control signal.
[0147] In still some other specific examples, please refer to FIG.
7 which is a structural schematic diagram of the timing circuit
module in another embodiment. As shown in the figure, the timing
circuit module can contain multiple capacitors, and each capacitor
is configured with a capacitor charge controller and a capacitor
discharge controller, multiple comparators and a logic device
group, etc. Wherein the configured capacitor discharge controller
is connected to a corresponding capacitor in parallel; the control
terminal of the configured capacitor charge controller receives the
first sampling control signal, the input terminal is accessed to a
constant voltage and the output terminal is connected with a
corresponding capacitor; one end of each of the capacitors is
grounded directly or via a resistor; another end of the capacitors
C1 is further connected with the negative input terminal of the
comparators A1 and A2; wherein the positive input terminal of the
comparator A1 is accessed to the reference voltage Vref 1, the
positive input terminal of the comparator A2 is accessed to the
reference voltage Vref 2; the negative input terminal of comparator
A3 is connected with another capacitor C2 and the positive input
terminal is accessed to the reference voltage Vref 3; the output
terminal of the comparators A1, A2 and A3 are all connected with
the logic device group, and the logic device group outputs the
second sampling control signal, wherein the reference voltage Vref
1 approaches 0V, and Vref 2 is a voltage value greater than Vref 1.
Through the design of the technicians, the duration of the voltage
of the capacitor C1 rising from Vref 1 to Vref 2 is shorter than
the existence duration of the first sampling control signal; and
the duration of the voltage of the capacitor C2 from the initial
value (such as 0V) to Vref 3 is longer than the existence duration
of a first sampling control signal. In the initial period, the
capacitor discharge controller CDC1 is short connected to the
capacitor C1 and the capacitor charge controller CCC1 is off, such
that the capacitor C1 is in a zero charge state, meanwhile, the
capacitor discharge controller CDC2 connected with the capacitor C2
is off and the capacitor charge controller CCC2 is on, such that
the capacitor C2 is in a charge saving state; correspondingly, the
comparators A1 and A2 output the low level while the comparator A3
outputs the high level; when the capacitor charge controller CCC1
connected with the capacitor C1 receives the first sampling control
signal, the capacitor charge controller CCC1 connected with the
capacitor C1 is on and the capacitor discharge controller CDC1 is
off, such that the capacitor C1 is charged. When the voltage of the
capacitor C1 is higher than the reference voltage Vref 1, the
comparator A1 outputs the high level and the comparator A2 still
outputs the low level, and when the comparators A1 and A3 output
the high level and the comparator A2 outputs the low level, the
logic device group outputs the second sampling control signal based
on the predetermined logic configuration; at this time, the
capacitor discharge controller CDC2 and the capacitor charge
controller CCC2 enable the capacitor C2 to discharge based on the
second sampling control signal, and the comparator A3 outputs the
low level; however, the capacitor C1 continues to be charged, such
that when the voltage reaches Vref 2, the comparator A2 jumps to
the high level, and when the comparators A1 and A2 both output the
high level and the comparator A3 outputs the low level, based on
the logic configuration, the logic device group does not output the
second sampling control signal, controls the capacitor charge
controller CCC1 to be off such that the capacitor C1 is not
charged, and controls the capacitor discharge controller CDC1 to be
on to discharge the charge of the capacitor C1. When the capacitor
C1 is discharged, the capacitor charge controller CCC2 of the
capacitor C2 is on and the capacitor discharge controller CDC2 is
off such that the capacitor C2 is charged, until the voltage of the
capacitor C2 reaches Vref 3, then the comparator A3 outputs the
high level, and when the comparator A3 outputs the high level,
based on the logic configuration, the logic device group outputs
the second sampling control signal based on the change of the level
of the comparators A1 and A2.
[0148] It should be noted that, the circuit structure of the timing
circuit module mentioned above is only exemplary, rather than
limiting the circuit structure of the timing circuit module in the
present application. In fact, based on the design of the timing
logic by the technicians, other timing circuit modules including a
comparator, a logic device group and a capacitor can also be
proposed; or, the timing circuit module containing a clock signal
generator and a counter can also be proposed, which are not
elaborated herein, however, the timing circuit module designed
based on the technical enlightment of the above timing circuit
module should be deemed as the specific example of the present
application. In addition, the devices in the above timing circuit
module can be included in the chip. To facilitate the periods of
various ACs provided by different AC input powers, the devices used
for timing, such as a capacitor and the peripheral devices or a
counter, in the timing circuit module can be assembled outside the
chip in which the leakage protection circuit is located, and the
devices can be controlled to acquire data through corresponding
pins, such that the technicians can select based on the
requirements of specific designs. Based on the design of the above
timing circuit modules, one example is as follows: the sampling
unit included in the leakage protection circuit samples the voltage
of the electrical signals from the power supply line during the
period in which the second sampling control signal is received.
[0149] It should also be noted that, as required by actual logic
design, the logic device group mentioned in any of the above
examples can contain at least one logic device, and all the logic
devices are electrically connected to realize corresponding logic
configuration, wherein the logic devices include but are not
limited to an AND gate, an OR gate, a NAND gate, a NOT gate, an
encoder, a decoder, a selector, etc.
[0150] The sampling unit is connected with the detection unit and
is configured to sample the electrical signals from the power
supply line based on the received sampling control signals.
[0151] Please refer to FIG. 8 which is a structural schematic
diagram of the leakage protection circuit in one embodiment. As
shown in the figure, wherein the sampling unit 12 contains a
controlled switch and a sampling resistor, wherein the control
terminal of the controlled switch is connected with the output
terminal of the detection unit, one access terminal of the
controlled switch is connected with the power supply line, while
the other access terminal is grounded via the sampling resistor,
and the sampling resistor is further connected with the control
unit 13. Wherein the controlled switch includes but is not limited
to any one of a triode (BJT), a junction field effect transistor
(JFET), a depletion MOSFET and thyristor. When the detection unit
11 outputs a sampling control signal, the controlled switch is on,
and the control unit 13 acquires the voltage of the sampled
electrical signals from the sampling resistor.
[0152] In one specific example, as shown in FIG. 8, the controlled
switch is an MOSFET as an example, the gate of the MOSFET is
connected with the output terminal of the detection unit, while the
drain of the MOSFET is connected with the power supply line and the
source is connected with the sampling resistor. Wherein based on
the detection unit described above, the MOSFET is on when receiving
the first sampling control signal or the second sampling control
signal, such that the control unit 13 acquires the sampled voltage
of the electrical signals from the power supply line.
[0153] The control unit is configured to compare the voltage of the
sampled electrical signals with the predetermined power-off
protection voltage threshold and providing leakage protection based
on the compared results.
[0154] Herein, the power-off protection voltage threshold
predetermined by the control unit can be supplied by a constant
voltage circuit. The power-off protection voltage threshold can be
designed based on the fact that the value of voltage drop of the
sampling unit will be influenced by the division of the AC input
power by human bodies. When the control unit determines that the
sampled voltage is lower than the power-off protection voltage
threshold, the power supply line may be controlled to be in
non-conductive state or the leakage protection control signals may
be output; otherwise, the power supply line is in conductive state
so as to enable the load to operate normally.
[0155] In one embodiment, the control unit contains a comparison
circuit module, a logic latch circuit module and a switch circuit
module, wherein the comparison circuit module is configured to
compare the voltage of the sampled electrical signals with the
predetermined power-off protection voltage threshold and output the
compared results. The logic latch circuit module is connected with
the comparison circuit module and is configured to latch the
compared results. The switch circuit module is connected with the
logic latch circuit module and is configured to control the
conductive state or non-conductive state of the power supply line
based on the latch signals.
[0156] Please refer to FIG. 9 which shows a waveform schematic
diagram of the voltage of sampled electrical signals received by
the comparison circuit module when voltage division is generated at
the AC input power side due to man-made misoperation and when the
load is connected to the power supply line normally with no
man-made voltage division, corresponding to the leakage protection
circuit as shown in FIG. 8. As shown in the figure, when the load
is connected to the power supply line with no man-made
misoperation, the sampled voltage is higher than the power-off
protection voltage threshold Vref; when the load is connected to
the power supply line with man-made misoperation, the sampled
voltage is lower than the power-off protection voltage threshold
Vref due to voltage division by human bodies. When the sampled
voltage is higher than the power-off protection voltage threshold
Vref, the comparison circuit module outputs a jumping signal, the
logic latch circuit module latches the jumping signal and outputs
the latch signal to a switch circuit module, and the switch circuit
module controls the power supply line to be in conductive state,
otherwise, the comparison circuit module does not output a jumping
signal, the logic latch circuit module does not output latch
signals, and the switch circuit module maintains the non-conductive
state of the power supply line, thereby protecting the safety of
the load and human.
[0157] In a specific example, the comparison circuit module
includes a comparator, and the switch circuit module includes the
controlled switch and a switch drive module, the negative input
terminal of the comparator is accessed to the power-off protection
voltage threshold and the positive input terminal of the comparator
is connected to the sampling unit to get the voltage of the sampled
electrical signals, the output terminal of the comparator is
connected to the input terminal of the logic latch circuit, and the
output terminal of the logic latch circuit module is connected to
the switch drive module. The switch circuit module includes a gate
drive module and an MOSFET as an example, the gate of the MOSFET is
connected with the output terminal of the logic latch circuit
through the gate drive module, and the source and the drain are
connected with the two ends of the power supply line, that is, the
MOSFET is a necessary part of the power supply line, the current
flow through the MOSFET. When there is no voltage division is
generated at the AC input power side, the comparator always outputs
the high level, and the MOSFET is turned on and the power supply
line is in conductive state such that the load works normally. In
another embodiment, the gate of the MOSFET is connected with the
output terminal of the comparator through the gate drive module and
the like. Please refer to FIG. 10 which is a structural schematic
diagram of the leakage protection circuit in another embodiment,
wherein the logic latch circuit module latches a high level state
when the comparison circuit module outputs the jump signal from a
low level to a high level, and latches a low level state when the
comparison circuit module outputs the jump signal from a high level
to a low level. In the initial period, the logic latch circuit
module is in a low level state, and the switch circuit module cuts
off the power supply line based on the received latch signals in a
low level state; and when the comparison circuit module outputs the
jump signal from a low level to a high level, the logic latch
circuit module latches the high level state and outputs the latch
signals in a high level state, then the switch circuit module is on
such that the power supply line is in conductive state. Therefore,
it can be seen that the latch signal is representing the leakage
protection control signal generated by the leakage protection
circuit.
[0158] Herein, the MOSFET in the controlled switch can also be
substituted into any one of a triode (BJT), a junction field effect
transistor (JFET), a depletion MOSFET and a thyristor. The switch
drive module is not necessarily a gate drive module, but can be
adjusted based on the actual design requirements. For example, the
switch circuit module includes an MOSFET and a source drive module,
etc.
[0159] In some other embodiments, the output terminal of the logic
latch circuit module is connected with the other circuits (such as
the drive circuit described above) connected with the power supply
line, such that the other circuits provide corresponding leakage
protection based on the latch signals, and this will not be
repeated redundantly herein.
[0160] It should be noted that, the comparative relationship
between the voltage of the sampled electrical signal with voltage
division by human bodies and the power-off protection voltage
threshold and the comparative relationship between the sampled
electrical signal voltage with no voltage division by human bodies
and the power-off protection voltage threshold as shown in the
above FIG. 9 are related to the circuit structure of the sampling
unit. When the circuit structure of the sampling unit is configured
in such a way that the voltage of the sampled electrical signals
with voltage division by human bodies is higher than the voltage of
the sampled electrical signals with no voltage division by human
bodies, the corresponding control unit should provide corresponding
leakage protection based on the compared results contrary to those
shown in FIG. 9. Wherein the circuit structure of the sampling unit
can also be of a connection manner in which one access terminal of
the controlled switch is connected to the power supply line via a
sampling resistor while the other access terminal of the controlled
switch is grounded, and the connection manners will not be
enumerated herein.
[0161] In order to prevent the logic latch circuit module from
providing wrong latch signals in the restarting operation after
users turn off the electrical appliance, when the power supply for
the load is interrupted, the logic latch circuit module needs to
reset to the initial low level state. In some specific examples,
the logic latch circuit module resets based on the fact that the
leakage protection circuit is in an undervoltage state.
[0162] Wherein the undervoltage state is a state in which the
voltage of the load cannot reach its normal working voltage due to
the influence of external factors or electrical appliance
components connected with or located on the power supply line in
the normal operating period of the load, such that the load is in a
state of not operating. The undervoltage state of the leakage
protection circuit is caused by man-made power failure or by
abnormity of the electrical appliance components inside (or
outside) the leakage protection circuit. For example, the instances
enabling the leakage protection circuit to be in an undervoltage
state include but are not limited to the power-off state of the
leakage protection circuit in the power off period and the state of
the leakage protection circuit when the power supply system cannot
provide corresponding operating voltage to the active device in the
leakage protection circuit.
[0163] The logic circuit module can reset the latched signals
through detecting the undervoltage state of the leakage protection
circuit. In one specific example, the reset terminal of the logic
latch circuit module is connected with a power supply line, when
the power supply of the power supply line is interrupted, the
leakage protection circuit is in an undervoltage state, and the
reset terminal of the logic circuit module receives effective reset
signals. In another specific example, the reset terminal of the
logic latch circuit module is connected with the undervoltage
protection circuit used for protecting the leakage protection
circuit, and when the undervoltage protection circuit generates
undervoltage protection signals due to the detection of an
undervoltage state of the leakage protection circuit, the reset
terminal of the logic latch circuit module takes the undervoltage
protection signal as the effective reset signal, thereby realizing
the reset operation of the logic latch circuit module.
[0164] In addition, due to the logic latch circuit module, when the
power supply line is in conductive state, the detection unit and
the sampling unit are not necessarily required to continuously
provide voltage of the electrical signals to continuously control
the on or off state of the switch circuit unit. Therefore, the
sampling of the power supply line at intervals is stopped when the
power supply line is controlled to be conductive. Wherein the
leakage protection circuit can add a control circuit module in the
detection unit or a sampling unit to correspondingly stop the
detection or sampling. In some specific examples, the control unit
is also connected with the detection unit, and is configured to
control the detection unit to stop outputting the sampling control
signals while control the power supply line to be conductive. For
example, the timing circuit module in the detection unit is further
connected with the output terminal of the logic latch circuit
module in the control unit, and when the logic latch circuit module
outputs the latch signals in a high level state, the timing circuit
module does not output the first sampling control signal or the
second sampling control signal, thereby effectively preventing such
problems as mis-power-off of the load caused by unstable voltage of
the AC input power.
[0165] When the power supply line is in conductive state, the drive
circuit in the drive device provides constant-current power supply
to the load based on the current rectified by the rectifying
circuit. Herein, one end of the drive circuit is connected on the
intersecting point between the leakage protection circuit and the
rectifying circuit, performs constant-voltage processing on the
received power supply to provide constant-current output to the
load, and returns to the grounded part controlled by the leakage
protection circuit via the load, thereby realizing a complete loop
of the power supply line.
[0166] In some embodiments, the drive circuit utilizes the
resonance principle to process the rectified current into operating
power supply of the load. Herein, the drive circuit includes an LC
oscillating unit and a switch control unit controlling the LC
oscillating unit. The switch control unit is used to perform the
switch control on the conductive or non-conductive state of the
oscillating loop in the LC oscillating unit so as to provide a
constant-current power supply to the load.
[0167] In other embodiments, the drive circuit provides
constant-current power supply to the load. Herein, the drive
circuit contains a line voltage compensation circuit. The line
voltage compensation circuit performs reversed linear compensation
on the rectified current through the at least one predetermined
linear compensation relationship, such that the current flowing
through the load is compensated, and constant-current power supply
is realized.
[0168] It should be noted that, the above drive mode and circuit
structure of the drive circuit are merely exemplary, rather than
limiting the present application. Aiming at the load of actually
being driven, the technicians can provide corresponding drive
circuit during use, which will not be enumerated herein. However,
any manner in which the drive circuit is connected with the leakage
protection circuit and the rectifying circuit and the load is
supplied with constant-current power supply should be deemed as a
specific example of the present application.
[0169] It should also be noted that, all or part of the electrical
appliances in the above drive circuit can be integrated in the
chip, and can be connected with the leakage protection circuit, the
rectifying circuit, the load and other peripheral circuits via the
pins. Wherein the peripheral circuits include but are not limited
to the electrical appliances not integrated in the drive circuit,
and the power supply line in the chip, etc. For example, the switch
control unit in the drive circuit is integrated in the
constant-current controller which is the product of our company,
the DRAIN pin of the series of chips can be used for being accessed
to the connecting node of the leakage protection circuit and the
rectifying circuit, the GND pin is used for connecting the switch
circuit module in the leakage protection circuit, and the CS pin is
connected with the LC oscillating unit. Please refer to FIG. 13
which is a structural schematic diagram of a drive device in one
embodiment, wherein the output terminal of the rectifying circuit
31 serves as an initiating terminal of the power supply line of the
load and is connected with the HV pin of the chip 32 containing the
leakage protection circuit, the electromagnetic interference (EMI)
circuit 33 in the drive device is configured to reduce the
electromagnetic interference on the power supply line, the DRAIN
pin of the constant-current controller 34 in the drive circuit is
accessed to the power supply line through connecting with the EMI
circuit, wherein the constant-current controller 34 controls the
conductive or non-conductive state of the DRAIN pin and the GND pin
via the electrical signals sampled by the CS and FB pins, and
further controls the post-stage LC oscillating unit 35 so as to
supply constant-current power supply to the LED load. The ground
pin of the constant-current controller 34 and the grounded end of
the LC oscillating unit 35 are both connected with the DRAIN pin of
the chip 32, and is grounded via the GND pin of the chip 32,
thereby realizing the control of the conductive or non-conductive
state of the whole power supply line by the leakage protection
circuit in the chip 32.
[0170] In addition, all or part of the circuits in the leakage
protection circuit and the drive circuit in the drive device can be
integrated in a drive chip. The drive chip is connected with the
rectifying circuit, electrical appliances which are not integrated
in the, the leakage protection circuit and the drive circuit, and
other peripheral circuits via the pin. The drive chip is configured
to perform leakage detection on the current rectified by the
rectifying circuit and drive the adaptive load, so as to supply
users with leakage protection and provide constant-current power
supply to the load, wherein the peripheral circuit includes the
power supply line of the chip as an example.
[0171] In one example, the drive chip contains the following pins:
HV, GND, DRAIN, CS and VCC, etc. Wherein the HV pin serves as a
current input terminal of the drive chip and is connected to the
power supply line which is connected with the output terminal of
the rectifying circuit, the DRAIN and GND pins connects the drive
chip to the ground wire loop of the power supply line, such that
the conductive or non-conductive state of the ground wire loop of
the power supply line is controlled by the drive chip. The leakage
protection circuit in the drive chip samples the power supply line
at intervals through detecting the HV pin, detects the voltage of
the sampled electrical signals so as to determine whether the
voltage of the AC input power is divided or not, and controls the
conductive or non-conductive state of the circuit between the DRAIN
and GND pins based on the determined results, thereby realizing
leakage protection. When the DRAIN and GND pins in the drive chip
are in conductive state, the drive circuit in the drive chip
samples the rectified electrical signals through the CS port and
supplies a constant current to the load based on the detection of
the sampled electrical signals. In addition, the VCC pin can be
used for being accessed to the constant-voltage source of the chip,
so as to supply a power source to the active devices in the chip,
and supply a constant reference voltage for electrical appliances
such as a comparator and an operational amplifier in the chip.
[0172] In another example, based on the actual design requirements
of the peripheral circuit of the chip and other circuits in the
drive device in which the chip is located, the chip can further
include a pin used for outputting the leakage protection control
signal. Wherein the leakage protection control signal is generated
and output when the leakage protection circuit confirms electric
leakage through sampling at intervals and voltage division
detection. Through the pin used for outputting the leakage
protection control signal, other circuits connected with the power
supply line can give corresponding leakage protection response
based on the received leakage protection control signals. Wherein
the other circuits include but are not limited to a filter circuit
and a drive circuit, etc. For example, as shown in FIG. 16, the
drive circuit includes an enable control unit (not shown in the
figure), the controlled terminal (namely, the enable terminal EN)
is connected with the output terminal of the leakage protection
circuit and the enable control unit drives the switch device or the
logic device in the drive circuit, the enable control unit controls
the switch device in the drive circuit to be non-conductive when
receiving the leakage protection control signal, such that the
energy converted by the drive circuit can not be provided to the
load until the leakage protection control signal is invalid, and
the switch device is switched into a conductive state, at this
time, the drive circuit can execute the drive operation. For
another example, as shown in FIG. 17, the drive chip contains an
enable control unit and an existing circuit in the constant-current
controller, the controlled terminal of the enable control unit is
connected with the output terminal of the leakage protection
circuit, the input terminal is connected with the power supply
terminal of the drive chip, and the output terminal is grounded;
and when the leakage protection circuit outputs the leakage
protection control signal, the enable control unit gives
corresponding leakage protection response based on the leakage
protection control signal, that is, make the power supply terminal
VCC of the constant-current controller be grounded, such that the
active device in the circuit in existing constant-current
controller cannot reach its normal operating voltage.
[0173] It should be noted that, the above existing constant-current
controller is merely exemplary, rather than limiting the present
application. By means of the enlightement of the above connection
relationship between the enable control unit and the chip, those
skilled in the art can add corresponding enable control unit to the
other drive chips which are not equipped with leakage protection,
such that the leakage protection can be realized by combining the
leakage protection circuit and the drive circuit.
[0174] It should be noted that, the quantity of pins of the drive
chip is related to the integrated circuit module, for example, some
capacitor devices in the drive circuit are not integrated in the
drive chip, then corresponding drive chip provides pins used for
connecting corresponding capacitor devices.
[0175] Please refer to FIG. 14 which is a flow chart of the leakage
protection method. The leakage protection method can be executed by
the above leakage protection circuit, or other leakage protection
circuits capable of executing the method.
[0176] In step S110, the power supply line of the load is sampled
at intervals.
[0177] Herein, the sampling interval can be set based on the
voltage change period of the power supply line. For example, the
electrical signals can be sampled at the voltage peak or the valley
in each rectified voltage change period or in at least every
rectified voltage change period, or the electrical signals can be
sampled in the fixed voltage area between the voltage peak and the
valley in each rectified voltage change period or in at least every
rectified voltage change period. Wherein in order to ensure that
human bodies will not be damaged by continuous electric shock
during unintended touch period, the sampling interval is a
millisecond or even a microsecond, for example, the sampling
interval may be every half of a voltage change period, every one
voltage change period or every multiple voltage change periods. The
sampling interval can be realized through the circuit structure
which is designed by utilizing the voltage change period in the
leakage protection circuit. Or, the sampling interval is set
according to the predetermined duration. For example, the leakage
protection circuit contains a capacitor and a resistor, and the
sampling interval is determined based on the charging duration of
the capacitor; wherein the technicians can design corresponding
sampling intervals through assembling a resistor. The resistor can
be an adjustable resistor or a fixed resistor.
[0178] In some embodiments, the electric signal voltage can be
sampled based on the sampling interval set according to the voltage
change period, and the electric signal voltage can be compared with
the predetermined power-off protection voltage threshold to
determine whether the voltage of the AC input power is divided or
not.
[0179] To this end, step S110 can contain a step of acquiring the
sampled electrical signals from the power supply line based on the
detection of the voltage of the power supply line and based on the
results of limited voltage detection.
[0180] Herein, the leakage protection circuit can detect the change
of the voltage of the power supply line in real time, and determine
to reach the sampling interval when detecting that the voltage
changes to the predetermined reference voltage value and acquire
the sampled electrical signals from the power supply line. Wherein
the predetermined reference voltage value can also be equal to any
voltage value correspond to the voltage change period, such as the
peak value, the valley value and the intermediate value.
[0181] In some embodiments, the leakage protection circuit can
detect the voltage of the power supply line, and acquire the
sampled electrical signals from the power supply line when the
detected voltage falls within the predetermined limited voltage
range, wherein the limited voltage range is intercepted in the
voltage change range of the power supply line, for example, the
limited voltage range is [V1,V2], wherein 0.ltoreq.V1<V2<V
max, and V max is the maximum value in the voltage change range.
Wherein the leakage protection circuit will execute one sampling in
each voltage change period.
[0182] In some other embodiments, the leakage protection circuit
acquires the sampled electrical signals from the power supply line
within a time limit when the detected voltage falls within the
predetermined limited voltage range. Wherein the limited sampling
duration is shorter than the duration in which the detected voltage
falls within the predetermined limited voltage range. The limit of
the sampling duration can effectively prevent mis-connectivity
operations caused by jittering of the sampled electrical signals.
For example, with reference to FIG. 4 which is a timing sequence
schematic diagram of the limited voltage detection circuit module
and the timing circuit module represented by respectively utilizing
the waveforms of the first sampling control signal and the second
sampling control signal, the leakage protection circuit samples the
electrical signals from the power supply line in the effective time
limit of the second sampling control signal. Wherein the first
sampling control signal is generated when the voltage of the power
supply line is detected to fall within the predetermined limited
voltage range, and the second sampling control signal is generated
from the first sampling control signal, and the second sampling
control signal is effective within a time limit. The leakage
protection circuit samples the electrical signals based on the
second sampling control signals.
[0183] In some embodiments, the leakage protection circuit is
configured to acquire the sampled electrical signals from the power
supply line after a predetermined detection timing is exceeded and
the voltage of the power supply line falls within a predetermined
limited voltage range. Please refer to FIG. 6 which is a waveform
schematic diagram of the relationship between the first sampling
control signal and the second sampling control signal in the
leakage protection circuit. As shown in the figure, wherein the
detection timing can enable that, within at least in one time
interval T2 of first sampling control signal, the timing circuit
module does not output the second sampling control signal based on
the first sampling control signal. Therefore, the existence
duration of the detection timing is the minimum time interval of
the second sample control signal, and the timing circuit module can
output the second sampling control signal in the case that the
detection timing is exceeded and the first sampling control signal
is effective, that is, the timing circuit module can output the
second sampling control signal based on the first sample control
signal only if the minimum time interval is satisfied. Further, the
sampling interval may be set based on the change period of the
voltage of the power supply line or based on a predetermined
duration, the minimum time interval also may be set based on the
change period of the voltage of the power supply line or based on a
predetermined duration. The leakage protection circuit acquires the
sampled electrical signals from the power supply line within the
duration time limit of the second sampled control signal.
[0184] Based on the technical concept mentioned above, the timing
circuit module may further set a sampling interval T3, during which
the limited voltage detection circuit module detects a voltage of
the power supply line and outputs a first sampling control signal
when the detected voltage falls within a predetermined limited
voltage range. For example, the timing circuit module is configured
to start the sampling interval T3 after T2 is exceeded, instruct
the limited voltage detection circuit module to detect the voltage
of the power supply line within T3, and output a first sampling
control signal when the detected voltage falls within a
predetermined limited voltage range. The timing circuit module is
configured to output a second sampling control signal based on the
received first sampling control signal, and start the time T2 and
perform loop operation.
[0185] In step S120, detection is conducted on the voltage of the
sampled electrical signals to determine whether the voltage of the
AC input power is divided or not.
[0186] Herein, in the leakage protection circuit, the sampled
voltage corresponding to the sampling instant can be compared with
the predetermined reference voltage corresponding to the sampling
instant to determine whether the voltage of the AC input power is
divided or not, so as to determine the conductive or non-conductive
state of the power supply line connected to the load. For example,
when detecting the voltage of the power supply line is zero, the
leakage protection circuit starts the timing of the sampling
interval, samples the electrical signals from the power supply line
when timing reaches, determines the voltage threshold when timing
reaches based on the voltage change period of the power supply
line, and compares the voltage of the sampled electrical signals
with the voltage threshold to determine whether the voltage of the
AC input power is divided or not.
[0187] In some embodiments, the power-off protection voltage
threshold is predetermined by the leakage protection circuit. The
power-off protection voltage threshold can be designed based on the
fact that the value of voltage drop of the sampling unit will be
influenced by the division of the AC input power by human bodies.
The leakage protection circuit compares the voltage of the sampled
electrical signals with the predetermined power-off protection
voltage threshold and outputs the compared results. For example,
when the load is connected to the power supply line normally, the
sampled voltage is higher than the power-off protection voltage
threshold; when the load is connected to the power supply line with
man-made misoperation, the sampled voltage is lower than the
power-off protection voltage threshold due to the voltage division
by human bodies.
[0188] It should be noted that, based on the circuit structure
design of the sampling unit, when the load is connected to the
power supply line normally, the sampled voltage is lower than the
power-off voltage threshold; when the load is connected to the
power supply line with man-made misoperation, the sampled voltage
is higher than the power-off protection voltage threshold due to
voltage division by human bodies.
[0189] In step S130, leakage protection is provided based on the
determined results.
[0190] In some embodiments, the leakage protection circuit compares
the voltage of the sampled electrical signals with the
predetermined power-off protection voltage threshold; when the
compared result is that the voltage of the AC input power is not
divided, the power supply line is controlled to be conductive; and
when the detection result is that the voltage of the AC input power
is divided, the power supply line is controlled to be
non-conductive.
[0191] In a specific example, the leakage protection circuit
contains a controlled switch connected onto the power supply line.
The controlled switch is an MOSFET as an example, when the voltage
of the electric signals is higher than or equal to the power-off
protection voltage threshold, the leakage protection circuit
controls the MOSFET to be turned on, otherwise, the leakage
protection circuit controls the MOSFET to be turned off.
[0192] In some other embodiments, the leakage protection circuit
can output the leakage protection control signals to other circuits
connected with the power supply line based on the determined
results. Wherein the leakage protection control signal is generated
and output when the leakage protection circuit confirms electric
leakage through sampling at intervals and voltage division
detection. Other circuits connected with the power supply line can
give corresponding leakage protection response based on the
received leakage protection control signals. Wherein the other
circuits include but are not limited to a filter circuit and a
drive circuit, etc. For example, the drive cuicuit connected with
the leakage protection circuit includes an enable control unit (not
shown in the figure), the controlled terminal (namely, the enable
terminal EN) is connected with the output terminal of the leakage
protection circuit and the enable control unit controls the switch
device or the logic device in the drive circuit, the enable control
unit controls the switch device in the drive circuit to be
non-conductive when receiving the leakage protection control
signal, such that the energy converted by the drive circuit can not
be provided to the load until the leakage protection control signal
is invalid, and the switch device is switched into a conductive
state, at this time, the drive circuit can execute the drive
operation. For another example, the drive circuit connected with
the leakage protection circuit contains an enable control unit and
an existing constant-current controller, the controlled terminal of
the enable control unit is connected with the output terminal of
the leakage protection circuit, the input terminal is connected
with the power supply terminal of the drive chip, and the output
terminal is grounded; and when the leakage protection circuit
outputs the leakage protection control signal, the enable control
unit gives corresponding leakage protection response based on the
leakage protection control signal, that is, make the power supply
terminal VCC of the constant-current controller be grounded, such
that the active device in existing constant-current controller
cannot reach its normal operating voltage.
[0193] In another embodiment, the leakage protection method further
includes a step of stopping sampling the power supply line at
intervals when the power supply line is controlled to be
conductive.
[0194] As when the power supply line is in conductive state, the
leakage protection circuit is not necessarily required to sample
the voltage of the electrical signals continuously at intervals to
continuously control the conductive of the switch circuit unit.
Therefore, the leakage protection circuit can correspondingly stop
generating the sampling control signals or stop sampling when the
power supply line is in conductive state.
[0195] It should be noted that, the above steps can be executed by
the corresponding circuit module of the leakage protection circuit
mentioned in the present application, and the structure of the
leakage protection circuit will not be repeated redundantly
herein.
[0196] Please refer to FIG. 15 which is a flow chart of the drive
method in one embodiment of the present application. The drive
method is mainly executed by the above drive device, or by the
other drive devices which can execute the method.
[0197] In step S210, the accessed AC is rectified and then provided
to the power supply line of the load.
[0198] Herein, the drive device is accessed to the AC input power
and is rectified and output via the rectifier bridge constituted by
four diodes.
[0199] In step S220, the power supply line is sampled at intervals.
Wherein the implementation of step S220 may be the same as or
similar to the implementation of step S110, and will not be
described in detail herein.
[0200] For example, the leakage protection circuit in the drive
device is configured to acquire the sampled electrical signals from
the power supply line after a predetermined detection timing is
exceeded and the voltage of the power supply line falls within a
predetermined limited voltage range. Please refer to FIG. 6 which
is a waveform schematic diagram of the relationship between the
first sampling control signal and the second sampling control
signal in the leakage protection circuit. As shown in the figure,
wherein the detection timing can enable that, within at least in
one time interval T2 of first sampling control signal, the timing
circuit module does not output the second sampling control signal
based on the first sampling control signal. Therefore, the
existence duration of the detection timing is the minimum time
interval of the second sample control signal, and the timing
circuit module can output the second sampling control signal in the
case that the detection timing is exceeded and the first sampling
control signal is effective, that is, the timing circuit module can
output the second sampling control signal based on the first sample
control signal only if the minimum time interval is satisfied.
Further, the sampling interval may be set based on the change
period of the voltage of the power supply line or based on a
predetermined duration, the minimum time interval also may be set
based on the change period of the voltage of the power supply line
or based on a predetermined duration. Wherein the first sampling
control signal is generated when the voltage of the power supply
line is detected to fall within the predetermined limited voltage
range, and the second sampling control signal is generated from the
first sampling control signal, and the second sampling control
signal is effective within a time limit. The leakage protection
circuit acquires the sampled electrical signals from the power
supply line within the duration time limit of the second sampled
control signal.
[0201] Based on the technical concept mentioned above, the timing
circuit module may further set a sampling interval T3, during which
the limited voltage detection circuit module detects a voltage of
the power supply line and outputs a first sampling control signal
when the detected voltage falls within a predetermined limited
voltage range. For example, the timing circuit module is configured
to start the sampling interval T3 after T2 is exceeded, instruct
the limited voltage detection circuit module to detect the voltage
of the power supply line within T3, and output a first sampling
control signal when the detected voltage falls within a
predetermined limited voltage range. The timing circuit module is
configured to output a second sampling control signal based on the
received first sampling control signal, and start the time T2 and
perform loop operation.
[0202] In step S230, detection is conducted on the voltage of the
sampled electrical signals to determine whether the voltage of the
AC input power is divided or not. Wherein the implementation of
step S230 may be the same as or similar to the implementation of
step S120, and will not be described in detail herein.
[0203] For example, the power-off protection voltage threshold is
predetermined by the leakage protection circuit in the drive
device. The power-off protection voltage threshold can be designed
based on the fact that the value of voltage drop of the sampling
unit will be influenced by the division of the AC input power by
human bodies. The leakage protection circuit compares the voltage
of the sampled electrical signals with the predetermined power-off
protection voltage threshold and outputs the compared results. For
example, when the load is connected to the power supply line
normally, the sampled voltage is higher than the power-off
protection voltage threshold; when the load is connected to the
power supply line with man-made misoperation, the sampled voltage
is lower than the power-off protection voltage threshold due to the
voltage division by human bodies.
[0204] In step 240, leakage protection is provided based on the
determined results. Wherein the implementation of step S240 may be
the same as or similar to the implementation of step S130, and will
not be described in detail herein.
[0205] For example, the leakage protection circuit in the drive
device contains a controlled switch connected onto the power supply
line. The controlled switch is an MOSFET as an example, when the
voltage of the electric signals is higher than or equal to the
power-off protection voltage threshold, the leakage protection
circuit controls the MOSFET to be turned on and step S250 is
executed, otherwise, the leakage protection circuit controls the
MOSFET to be turned off to provide leakage protection.
[0206] In step S250, power supply is provided to the load on the
power supply line.
[0207] For example, the drive circuit in the drive device utilizes
the resonance principle to process the rectified current into
operating power supply of the load. For another example, the drive
circuit in the drive device utilizes line voltage compensation
method to process the rectified current into operating power supply
of the load.
[0208] In conclusion, the technical solution in the present
application can prevent human from electric shock through sampling
the electric signals from the power supply line at intervals and
performing voltage detection and comparasion to determine whether
the voltage of the accessed AC input power is divided, when the
voltage of the accessed AC input power is determined to be divided,
the power supply line will be controlled in non-conductive
state.
[0209] While preferred embodiments of the present invention have
been shown and described herein, it will be obvious to those
skilled in the art that such embodiments are provided by way of
example only. It is not intended that the invention be limited by
the specific examples provided within the specification. While the
invention has been described with reference to the aforementioned
specification, the descriptions and illustrations of the
embodiments herein are not meant to be construed in a limiting
sense. Numerous variations, changes, and substitutions will now
occur to those skilled in the art without departing from the
invention. Furthermore, it shall be understood that all aspects of
the invention are not limited to the specific depictions,
configurations or relative proportions set forth herein which
depend upon a variety of conditions and variables. It should be
understood that various alternatives to the embodiments of the
invention described herein may be employed in practicing the
invention. It is therefore contemplated that the invention shall
also cover any such alternatives, modifications, variations or
equivalents. It is intended that the following claims define the
scope of the invention and that methods and structures within the
scope of these claims and their equivalents be covered thereby.
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