U.S. patent application number 13/932495 was filed with the patent office on 2013-11-07 for solid state semiconductor led replacement for fluorescent lamps.
The applicant listed for this patent is Laurence P. Sadwick. Invention is credited to Laurence P. Sadwick.
Application Number | 20130293131 13/932495 |
Document ID | / |
Family ID | 41652268 |
Filed Date | 2013-11-07 |
United States Patent
Application |
20130293131 |
Kind Code |
A1 |
Sadwick; Laurence P. |
November 7, 2013 |
Solid State Semiconductor LED Replacement for Fluorescent Lamps
Abstract
Various apparatuses and methods for replacing a fluorescent lamp
with a non-fluorescent tube are disclosed herein. For example, some
embodiments provide an apparatus for replacing a fluorescent lamp,
including an electrical connector adapted to electrically connect
to a fluorescent lamp fixture, a DC rectifier connected to the
electrical connector, a voltage converter connected to the DC
rectifier, and a non-fluorescent light source connected to the
voltage converter. The DC rectifier, voltage converter and
non-fluorescent light source are substantially contained within a
housing that is physically configured to replace the fluorescent
lamp in a fluorescent lamp fixture.
Inventors: |
Sadwick; Laurence P.; (Salt
Lake City, UT) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Sadwick; Laurence P. |
Salt Lake City |
UT |
US |
|
|
Family ID: |
41652268 |
Appl. No.: |
13/932495 |
Filed: |
July 1, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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12367539 |
Feb 8, 2009 |
8502454 |
|
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13932495 |
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61027115 |
Feb 8, 2008 |
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Current U.S.
Class: |
315/200R |
Current CPC
Class: |
H05B 31/50 20130101;
F21K 9/27 20160801; H05B 45/50 20200101; H05B 45/3725 20200101;
Y02B 20/30 20130101; H05B 45/37 20200101 |
Class at
Publication: |
315/200.R |
International
Class: |
H05B 33/08 20060101
H05B033/08 |
Claims
1-20. (canceled)
21. An apparatus for replacing a fluorescent lamp, the apparatus
comprising: a constant current driver operable to receive
electrical current from a fluorescent lamp fixture and operable to
power a non-fluorescent light source, wherein the constant current
driver comprises startup and feedback circuitry operable to
simulate the electrical behavior of a fluorescent tube when no
fluorescent tube is installed in the fluorescent lamp fixture.
22. The apparatus of claim 21, wherein the non-fluorescent light
source comprises at least one organic light emitting diode.
23. The apparatus of claim 21, wherein the constant current driver
is operable to be dimmed by a wall dimmer.
24. The apparatus of claim 21, wherein the constant current driver
is operable to receive the electrical current from a magnetic
ballast in the fluorescent lamp fixture.
25. The apparatus of claim 21, wherein the constant current driver
is operable to receive the electrical current from an electronic
ballast in the fluorescent lamp fixture.
26. The apparatus of claim 21, wherein the constant current driver
is operable to control a color of the non-fluorescent light
source.
27. The apparatus of claim 26, wherein the non-fluorescent light
source comprises a red, green and blue light source.
28. The apparatus of claim 21, wherein the constant current driver
is operable to store color choices.
29. The apparatus of claim 21, further comprising a housing
containing the constant current driver, and comprising a color
filter in the housing.
30. The apparatus of claim 21, wherein the constant current driver
is operable to operate with magnetic and electronic ballasts in the
fluorescent lamp fixture.
31. The apparatus of claim 21, wherein the constant current driver
is operable to receive the electrical current from the fluorescent
lamp fixture when no ballast is installed in the fluorescent light
fixture.
32. The apparatus of claim 21, further comprising power factor
correction circuitry connected to the constant current driver.
33. The apparatus of claim 21, further comprising a dimming control
circuit connected to the constant current driver and operable to
control dimming of the power to the non-fluorescent light
source.
34. The apparatus of claim 33, wherein the dimming control circuit
comprises a wireless interface operable to control the constant
current driver.
35. The apparatus of claim 34, wherein the wireless interface
comprises an infrared interface.
36. The apparatus of claim 34, wherein the wireless interface
comprises an optical interface.
37. The apparatus of claim 33, wherein the dimming control circuit
comprises a wired interface operable to control the constant
current driver.
38. The apparatus of claim 33, wherein the dimming control circuit
comprises a digital addressable lighting interface operable to
control the constant current driver.
39. The apparatus of claim 33, wherein the dimming control circuit
comprises a 0 to 10 volt interface operable to control the constant
current driver.
40. The apparatus of claim 21, further comprising a light sensor
input operable to control dimming of the power to the
non-fluorescent light source.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] The present application claims priority to U.S. Provisional
Patent Application No. 61/027,115 entitled "All Solid State
Semiconductor LED Replacement For Fluorescent Lamps", filed Feb. 8,
2008. The aforementioned application is assigned to an entity
common hereto, and the entirety of the aforementioned application
is incorporated herein by reference for all purposes.
BACKGROUND
[0002] Lighting is needed in many applications including both
consumer/residential and commercial markets. Fluorescent tube
lighting is a significant source of lighting in many applications,
particularly in commercial markets, for a number of reasons such as
higher efficiency and longer life than incandescent bulbs. However,
newer solid semiconductor lighting such as light emitting diodes
(LEDs) have been developed having advantages over fluorescent tube
lighting. Conversion from fluorescent tube lighting to newer
technologies can be prohibitively costly due to characteristics
that are fundamentally associated with fluorescent lighting. In
general, fluorescent lights and lamps cannot run directly off the
alternating current (AC) mains. To make fluorescent lighting
practical and relatively easy to use, a ballast 10 is required to
be placed between the AC mains 12 and the fluorescent lamp or tube
14 as illustrated in FIG. 1 to control and regulate the voltage,
current and power applied to the fluorescent lamp 14.
[0003] As a result, large fluorescent light fixtures including
heavy ballasts 10, reflectors 16, and specific fluorescent tube
connectors 20 are mounted in offices and homes around the world.
Conversion from fluorescent tube lighting generally requires that
the fluorescent lighting fixture or at least the ballast 10 be
removed so that replacement lighting technology not requiring a
ballast may be installed.
SUMMARY
[0004] Various apparatuses and methods for replacing a fluorescent
lamp with a non-fluorescent tube are disclosed herein. For example,
some embodiments provide an apparatus for replacing a fluorescent
lamp, including an electrical connector adapted to electrically
connect to a fluorescent lamp fixture, a DC rectifier connected to
the electrical connector, a voltage converter connected to the DC
rectifier, and a non-fluorescent light source connected to the
voltage converter. The DC rectifier, voltage converter and
non-fluorescent light source are substantially contained within a
housing that is physically configured to replace the fluorescent
lamp in a fluorescent lamp fixture.
[0005] In an embodiment of the apparatus for replacing a
fluorescent lamp, the non-fluorescent light source comprises at
least one LED.
[0006] In an embodiment of the apparatus for replacing a
fluorescent lamp, the apparatus is adapted to connect through the
electrical connector to an AC output of a fluorescent ballast in
the fluorescent lamp fixture.
[0007] In an embodiment of the apparatus for replacing a
fluorescent lamp, the fluorescent ballast comprises a magnetic
ballast.
[0008] In an embodiment of the apparatus for replacing a
fluorescent lamp, the fluorescent ballast comprises an electronic
ballast.
[0009] In an embodiment of the apparatus for replacing a
fluorescent lamp, the voltage converter is adapted to reduce a
voltage from the DC rectifier.
[0010] In an embodiment of the apparatus for replacing a
fluorescent lamp, the apparatus includes protection circuitry
connected between the electrical connector and the DC rectifier in
the housing. The protection circuitry is adapted to prevent a
voltage exceeding a threshold value from passing through the
protection circuitry.
[0011] In an embodiment of the apparatus for replacing a
fluorescent lamp, the apparatus includes startup and feedback
circuitry connected to the DC rectifier in the housing. The startup
and feedback circuitry is adapted to simulate an electrical
behavior of a fluorescent tube in response to a startup sequence
from a ballast in the fluorescent lamp fixture.
[0012] In an embodiment of the apparatus for replacing a
fluorescent lamp, the apparatus includes a power factor correction
circuit connected to the DC rectifier in the housing.
[0013] In an embodiment of the apparatus for replacing a
fluorescent lamp, the apparatus includes a cathode heater
simulation circuit in the housing and switchably connected to the
electrical connector. The cathode heater simulation circuit is
adapted to simulate a fluorescent tube cathode when a ballast in
the fluorescent lamp fixture is in a cathode heating mode.
[0014] In an embodiment of the apparatus for replacing a
fluorescent lamp, the voltage converter comprises a pulse generator
and a constant current driver.
[0015] In an embodiment of the apparatus for replacing a
fluorescent lamp, the apparatus includes a current overload
protection circuit connected to the voltage converter in the
housing.
[0016] In an embodiment of the apparatus for replacing a
fluorescent lamp, the apparatus includes a thermal protection
circuit connected to the voltage converter in the housing. The
thermal protection circuit is adapted to reduce a current to the
non-fluorescent light source in inverse proportion to a temperature
of the apparatus.
[0017] In an embodiment of the apparatus for replacing a
fluorescent lamp, the apparatus includes a dimming circuit
connected to the voltage converter in the housing. The dimming
circuit is adapted to controllably reduce a current to the
non-fluorescent light source.
[0018] Other embodiments provide a method of powering an LED
replacement tube in a fluorescent lamp fixture. The method includes
receiving an AC voltage input from the fluorescent lamp fixture,
and converting the AC voltage to a power source for at least one
LED in the LED replacement tube. The converting is performed by a
power converter in the LED replacement tube.
[0019] In an embodiment of the method of powering an LED
replacement tube in a fluorescent lamp fixture, the method includes
rectifying the AC voltage to a DC voltage before the
converting.
[0020] In an embodiment of the method of powering an LED
replacement tube in a fluorescent lamp fixture, the method includes
electrically simulating a fluorescent tube response to a startup
sequences from a ballast in the fluorescent lamp fixture. The
simulating is performed in the LED replacement tube.
[0021] In an embodiment of the method of powering an LED
replacement tube in a fluorescent lamp fixture, the method includes
controlling a power factor of the LED replacement tube resulting in
a higher power factor, wherein the controlling is performed in the
LED replacement tube.
[0022] In an embodiment of the method of powering an LED
replacement tube in a fluorescent lamp fixture, the method includes
dimming the at least one LED by reducing a current to the at least
one LED in the LED replacement tube, wherein the dimming is
performed in the LED replacement tube.
[0023] Other embodiments provide an apparatus for replacing a
fluorescent lamp. The apparatus includes an electrical connector
adapted to electrically connect to an AC output of a fluorescent
ballast in the fluorescent lamp fixture. The apparatus also
includes a cathode heater simulation circuit switchably connected
to the electrical connector. The cathode heater simulation circuit
is adapted to simulate a fluorescent tube cathode when a ballast in
the fluorescent lamp fixture is in a cathode heating mode. The
apparatus also includes a protection circuit connected to the
electrical connector. The protection circuit is adapted to prevent
a voltage exceeding a threshold value from passing through the
protection circuit. The apparatus also includes a DC rectifier
connected to the protection circuit, a power factor correction
circuit connected to the DC rectifier. The apparatus also includes
a startup and feedback circuit connected to the DC rectifier. The
startup and feedback circuit is adapted to simulate an electrical
behavior of a fluorescent tube in response to a startup sequence
from a ballast in the fluorescent lamp fixture. The apparatus also
includes a voltage converter connected to the DC rectifier and
adapted to reduce a voltage from the DC rectifier. The apparatus
also includes a current overload protection circuit connected to
the voltage converter. The apparatus also includes a thermal
protection circuit connected to the voltage converter. The thermal
protection circuit is adapted to reduce a current from the voltage
converter in inverse proportion to a temperature of the apparatus.
The apparatus also includes a dimming circuit connected to the
voltage converter. The dimming circuit is adapted to controllably
reduce a current from the voltage converter. The apparatus also
includes at least one LED connected to the voltage converter. The
apparatus also includes a housing substantially containing the
cathode heater simulation circuit, DC rectifier, power factor
correction circuit, startup and feedback circuit, voltage
converter, current overload protection circuit, thermal protection
circuit, dimming circuit and at least one LED. The housing is
physically configured to replace the fluorescent lamp in the
fluorescent lamp fixture.
[0024] This summary provides only a general outline of some
particular embodiments. Many other objects, features, advantages
and other embodiments will become more fully apparent from the
following detailed description, the appended claims and the
accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0025] A further understanding of the various embodiments may be
realized by reference to the figures which are described in
remaining portions of the specification. In the figures, like
reference numerals may be used throughout several drawings to refer
to similar components.
[0026] FIG. 1 depicts a prior art fluorescent lamp fixture.
[0027] FIG. 2 depicts a fluorescent lamp fixture with a solid state
semiconductor LED replacement for a fluorescent lamp with a single
ended power converter in accordance with some embodiments.
[0028] FIG. 3 depicts a fluorescent lamp fixture with a solid state
semiconductor LED replacement for a fluorescent lamp with a double
ended power converter in accordance with some embodiments.
[0029] FIG. 4 depicts a fluorescent lamp fixture with a solid state
semiconductor LED replacement for a fluorescent lamp with
multi-directional LED orientation in accordance with some
embodiments.
[0030] FIG. 5 depicts a block diagram of a power converter in
accordance with some embodiments.
[0031] FIG. 6 depicts a block diagram of a power converter for use
with a magnetic ballast in accordance with some embodiments.
[0032] FIG. 7 depicts a block diagram of a power converter with
power factor correction circuitry in accordance with some
embodiments.
[0033] FIG. 8 depicts a block diagram of a power converter with
power factor correction circuitry in accordance with some
embodiments.
[0034] FIG. 9 depicts a block diagram of a power converter for use
with an electronic ballast in accordance with some embodiments.
[0035] FIG. 10 depicts a block diagram of a power converter with
protection and ballast handling circuitry in accordance with some
embodiments.
[0036] FIG. 11 depicts a block diagram of a power converter for use
without a fluorescent ballast in accordance with some
embodiments.
[0037] FIG. 12 depicts a block diagram of a power converter for use
without a fluorescent ballast and including current overload and
thermal protection in accordance with some embodiments.
[0038] FIG. 13 depicts a block diagram of a power converter with
current overload and thermal protection circuitry in accordance
with some embodiments.
[0039] FIG. 14 depicts a block diagram of a power converter in
accordance with some embodiments.
[0040] FIG. 15 depicts a block diagram of a power converter
operating in an AC mode in accordance with some embodiments.
[0041] FIG. 16 is a flow chart of an exemplary operation for
powering an LED replacement tube in a fluorescent lamp fixture.
DESCRIPTION
[0042] The drawings and description, in general, disclose various
embodiments of a solid state semiconductor LED replacement for
fluorescent lamps. An embodiment is illustrated in FIG. 2, wherein
a fluorescent lamp fixture includes an AC input 12 powering a
ballast 10. An LED replacement tube 22 is inserted into the
fluorescent lamp fixture in place of a fluorescent tube. The LED
replacement tube 22 includes one or more electrical connectors 24
extending from the housing 26 of the LED replacement tube 22 to
connect to the fluorescent tube connectors 20 in the fixture. The
LED replacement tube 22 includes one or more non-fluorescent light
sources, such as LEDs 30, that are electrically connected to a
power converter 32, for example on a printed circuit board 34 or
other electrically connective support structure. It is to be
understood that the light sources in the LED replacement tube 22
can be any non-fluorescent light source, including LEDs and organic
light emitting diodes (OLEDs). Thus, the term LED has been used
generically throughout this document, including in the claims, to
refer to any light source other than a fluorescent light source,
including LEDs and OLEDs. The power converter 32 in various
embodiments is adapted to draw power from the ballast 10 or from
the AC mains 12 in the absence of a ballast 10 or given a
non-functional ballast 10, and to convert the power from the
ballast 10 or AC mains 12 for use by the LEDs 30. In other
embodiments as illustrated in FIG. 3, multiple power converters 32
and 36 may be included, connecting in the fluorescent lamp fixture
at both ends of the LED replacement tube 22. Any desired number and
orientation of LEDs 30 may be included. For example, the LEDs 30
may be oriented to direct light substantially downward across an
angle such as 180 degrees, or may be oriented across wider angles
as illustrated in FIG. 4 to more closely resemble the light output
of a fluorescent tube, thereby reflecting off a reflector 40 above
the LED replacement tube 22 in the fluorescent lamp fixture.
[0043] The LED replacement tube 22 disclosed herein provides a high
efficiency long life lamp replacement that is more environmentally
friendly than fluorescent tubes. The LED replacement tube 22 may be
used in place of fluorescent or neon tubes and is form function
compatible with existing lamp fixtures and ballasts, both of the
magnetic and electrical types of operation over a wide voltage
range of operation offering high efficiency, high power factor and
long life with environmentally friendly materials. The LED
replacement tube 22 makes use of the standard tubular, spiral, or
any other standard form factor lamp and ballast and related
fixtures to allow an LED light source in a variety of shapes,
sizes, colors, arrays, etc. to be used and inserted into existing
and new fluorescent lamp fixtures of any length and any power,
voltage and current combination. In one embodiment, the housing 26
consists of a tube that can be made of any suitable material
including glass and/or plastic. In other embodiments, the housing
26 may have other shapes and sizes and may include a mixture of
different materials, such as an opaque plastic upper portion and a
substantially transparent plastic or glass lower portion. Yet other
embodiments may have a partially open housing 26, such as an
exposed support structure, e.g., a printed circuit board, with LEDs
30 mounted thereon and exposed to the air without covering. The LED
replacement tube 22 may use any suitable type, number and
configuration of LEDs 30 such as, for example, ultraviolet LEDs
with a phosphor coating on the LEDs or on the housing 26 itself to
produce suitable output light in the desired wavelength regions
(i.e., white or visible light), or may use any number and
combination of different colored LEDs to accomplish the desired
illumination performance. The LED or LED array 30 is contained
within the housing 26 and may have any shape or form including but
not limited to circular, cylindrical, triangular, rectangular,
square, string, helical, spiral, polygonal, perpendicular, etc. The
power converter 32 is also contained within the housing 26 to
convert the input alternating current (AC) voltage/current/power
into the appropriate DC output required for the LED or LED arrays
30 to operate.
[0044] In one embodiment, the power converter 32 may supply an AC
output of suitable voltage and frequency to drive LEDs connected in
parallel and inverse fashion, that is, a parallel array of LEDs
arranged anode to cathode and cathode to anode. In addition to the
power converter 32 and LEDs 30, the LED replacement tube 22 may
include various types of interfaces that permit both wired and
wireless communications with the power converter 32 to permit
monitoring, control, dimming, turn on, turn off, light sensor
input, various sensor input, human input, automated and automated
control system input etc., Bluetooth, web/internet-based, WIMAX,
WIFI, telephone, cellular phone and all other types and standards
for communications, etc. The support circuitry may be contained
either entirely within the LED replacement tube 22, may be located
outside the housing 26, or partially inside and partially outside.
The power converter 32 may be adapted to operate with the existing
ballast in place in the light fixture, or with the ballast removed
and bypassed in the fixture.
[0045] Again, the LEDs 30 may be directed in any desired manner,
such as a unidirectional orientation to illuminate in one direction
from the LED replacement tube 22 as illustrated in FIGS. 2 and 3,
or may be configured to illuminate substantially in all directions,
or in any other custom spotlight fashion (e.g., FIG. 4). Reflectors
may also be included within the LED replacement tube 22 to produce
the desired output.
[0046] Various embodiments of the power converter 32 in the LED
replacement tube 22 are adapted to work with one or more types of
ballasts 10 and fluorescent lamp fixture configurations. Ballasts
10 typically fall within one of two broad categories, magnetic and
electric. Magnetic ballasts in general are older and less efficient
ballasts that typically include an inductive coil and a starter
circuit. Magnetic ballasts are also prone to failure after a
certain number of years. In addition to being inefficient, magnetic
ballasts also present poor electrical characteristics to the AC
mains which can be viewed in terms of having a poor power factor.
The output of a magnetic ballast should be an ideal sine wave
usually at the same frequency as the AC mains (in general 50 to 60
hertz), however, the discussion and application discussed here is
fully applicable to higher frequency (i.e., 400 Hz) magnetic
ballasts. This sine wave can have the same or similar amplitude as
the AC mains or the sine wave can have a higher amplitude than the
AC mains. Typically magnetic ballasts have amplitudes similar to
the AC mains which, depending on the type and diameter of the
fluorescent tube, can range from around 100 V AC RMS up to over 400
V AC RMS with 120, 240 and 277 V AC RMS being commonly used in the
United States.
[0047] Electronic ballasts are newer and more modern ways to
efficiently light fluorescent lamps. Whereas magnetic ballasts tend
to be very similar in their performance and operation and in
general lack "smarts" or electronic intelligence, electrical
ballasts have been designed and implemented in a wider variety from
very simple to very complicated versions. Electronic ballasts
include versions that have built in microprocessors and/or
microcontrollers and other such electronic state machines capable
of executing simple to complex timing sequences that are often
required to best optimize factors such as the efficiency and
lifetime of the fluorescent lamp based on the intrinsic and
fundamental physics of the gas discharge and plasma physics and
processes that govern fluorescent lamps. These electronic ballasts
can be designed to provide excellent power factor correction and
can be made to be very efficient in terms of electrical power usage
and consumption. In addition, electronic ballasts can also be used
to make decisions as to the condition and health of the fluorescent
tube and even make a decision as to whether the fluorescent tube is
no longer functional (i.e., burned out) or even present (i.e.,
installed). These types of decisions are typically based on
electronic and electrical information fed back to the ballast
during and after the electronic ballast is or is in the process of
applying voltages, energy and power to the fluorescent lamp. Based
on the sequence and responses to these voltages, the ballast is
often designed to decide if the fluorescent lamp is behaving
properly and in a normal mode such that a plasma discharge has been
struck in the lamp and appropriate current is flowing through the
fluorescent lamp(s). If the ballast receives information that
indicates that there was not a turn on of or strike in the
fluorescent lamp then, depending on the ballast design, the ballast
may continue repeating the turn on sequence or may effectively shut
down until commanded, typically by human intervention, to retry and
restart the startup sequence. There are numerous variations of this
basic approach depending on the design, manufacturer, end user,
etc. of the electronic ballast. To complicate matters further, the
output frequency and voltage can range from around b 30 kHz (i.e.,
above the human audio range) to upwards of 100 kHz and even higher,
again depending on the ballast design and intended application.
[0048] In addition to the output frequency bearing no direct
relationship to the input AC mains frequency, the output voltages
also in general bear no direct relationship to the input AC mains
voltages, but instead are typically chosen based on the type of
fluorescent lamp (with the diameter and length of the lamp being
major considerations). As the use of "smart" electronics allows the
possibility of huge and sometimes subtle variations in the start-up
sequence that the ballast presents to the fluorescent lamp
including how and when (i.e., the timing sequence and method of
applying voltage to the fluorescent lamp) the ballast responds to
the information fed back to the ballast from the lamp, it is
important that the lamp behave in most every way in a manner that
would be expected from a fluorescent lamp/light source. Fluorescent
lamps also have heaters (which are also commonly referred to as
filaments or cathodes) at each end of the lamp. How these
heaters/filaments/cathodes are used and the associated timing
sequence can have a dramatic effect on the life of the fluorescent
tube and, in some cases, the life of the ballast as well.
[0049] There are three commonly recognized pre-heating or heating
sequences utilized in electronic ballasts to strike or turn on the
fluorescent lamp. These three sequences are often referred to as
the preheat start, the instant start, and the rapid start. With the
preheat start, power is first applied to the cathodes typically
from less than one second to at most a few seconds before
attempting to breakdown the gas in the fluorescent tube and strike
a plasma. With instant start, no power is applied to the cathodes
or power is applied at the same time as the high voltage is applied
and this high voltage is applied across the fluorescent tube to
strike a plasma with or without the assistance of electrons created
at the cathodes. With rapid start, the cathodes are always heated
resulting in a fast rapid start at the expense of "wasted energy"
when the fluorescent lamp is not on (i.e., not lit for producing
light). There are also variations of these three sequences that are
used with and in electronic ballasts. During the start up sequence,
the voltages that electronic ballasts put out can typically range
from hundreds of volts up to one thousand volts or more depending
on the ballast design and intended fluorescent tube type(s) (i.e.,
T12, T9, T8, T5, etc.) that the ballast is intended to drive,
operate, support, etc. A common type of electronic ballast design
uses a multi frequency or sweeping frequency resonance approach to
breakdown the gas and strike a plasma in the fluorescent tube. The
open circuit voltage of such a resonant approach can be quite high
(in the thousands of volts) depending on a number of factors
including the quality factor (Q) of the circuit.
[0050] In certain applications it may be desirable or necessary to
replace fluorescent tubes with other light sources such as solid
state light sources including LEDs and OLEDs. In general there are
significant differences between fluorescent light sources and LED
and OLED light sources. In general, fluorescent light sources
require AC voltages containing as little as possible direct current
(DC) voltages whereas, in general, LED and OLED light sources
require primarily DC voltages and are potentially damaged by large
AC voltages that swing in the negative direction (which reverse
biases the LED and produces no light output) unless the LEDs or
LEDs are arranged in a back to back configuration (i.e., for
example, two LEDs are put in parallel with the cathode of the first
LED attached to the anode of the second LED, and the anode of the
first LED attached to cathode of the second LED). Needless to say,
there can be numerous variations of the back to back configuration
involving multiple LEDs (or OLEDs) placed in various parallel and
series configurations. The voltage applied in these configurations
should not exceed the reverse breakdown of any LED as doing so may
cause damage or fatal failure to one or more of the LEDs.
[0051] In general, the LED replacement tube 22 used with an
existing ballast 10 mimics both the behavior of a fluorescent tube
lamp and also is adapted to survive the potentially high voltages
associated with fluorescent lamps and ballasts.
[0052] Various embodiments of LED replacement tube 22 may
include:
[0053] An integral AC to DC, AC to AC, or DC to DC circuit.
[0054] Circuitry to identify and handle instant on, rapid on and
pre-heat sequences.
[0055] Circuitry designed specifically for use with magnetic or
electronic ballasts or universal circuitry for use with both
magnetic and electronic ballasts.
[0056] Protection circuitry to handle potentially high turn on
voltages of ballasts.
[0057] Strike current mimic functionality to allow/permit ballast
to determine that it is receiving the correct feedback.
[0058] High power factor correction for magnetic and low frequency
ballasts.
[0059] Universal voltage ballast translator.
[0060] Power converters to convert high voltage AC into constant
current DC.
[0061] Dimming functionality using conventional wall dimmers,
infrared, wireless, analog, low voltage, Ethernet, USB, I2C, RS232,
optical, parallel, UART, and other types of wired and wireless
digital and/or analog transceivers, etc.
[0062] Color rendering, color monitoring, color feedback and
control.
[0063] Temperature monitoring, feedback, and adjustment.
[0064] The ability to change to different colors when using light
sources capable of supporting such(i.e., LEDs including but not
limited to red, green, blue LEDs and/or any other possible
combination of LEDs and colors).
[0065] The ability to store color choices, selections when using
non-fluorescent light sources that can support color changing.
[0066] The ability to change between various color choices,
selections, and associated inputs to do.
[0067] The ability to modulate the color choices and
selections.
[0068] The use of either passive or active color filters and
diffusers to produce enhanced lighting effects.
[0069] Circuitry to handle AC voltages up to and above 1 kV in
amplitude and 100 KHz in frequency.
[0070] Referring now to FIG. 5, various embodiments of the LED
replacement tube 22 will be described. An AC output 50 from a
ballast 10 supplies power to a conversion circuit 52 within the LED
replacement tube 22. The AC output 50 from a ballast 10 may have a
frequency of 30 kHz up to 100 kHz or even higher, with a voltage of
about 150 VAC up to 1000 VAC peak or more depending on the
fluorescent tube and cathode being used. The conversion circuit 52
includes protection circuitry 54 that protects other components of
the conversion circuit 52 and LEDs 30 from being damaged by high
voltage/current/frequencies from the ballast 10 when it is turned
on. The protection circuitry 54 may lower the voltage, or may
harmlessly discharge the voltage if it exceeds a threshold value so
that it cannot damage other components of the conversion circuit
52. For example, the protection circuitry 54 may include a spark
gap connected in parallel with the connections from the AC output
50, shorting across the AC output 50 to discharge the voltage to
prevent damage to the conversion circuit 52. In other embodiments,
the protection circuitry 54 may include a switchably connected load
that is applied when the voltage rises above a threshold value,
loading down the ballast 10 and reducing the voltage, then being
disconnected when the voltage falls to avoid triggering fault
detection in the ballast 10. The protection circuitry 54 may also
include a feedback controlled switch to connect or disconnect power
from the AC output 50 to other elements of the conversion circuit
52.
[0071] A DC rectifier 56 is connected to the protection circuitry
54 to convert the AC power from the AC output 50 to DC power for
use by the LEDs 30. Depending on the type of ballast 10 for which
the conversion circuit 52 is intended, the DC rectifier 56 may be a
high voltage rectifier, for example a 1 kV or 1.2 kV (or higher
voltage) diode bridge of four or more diodes.
[0072] A voltage converter 60 such as a boost/buck or buck
converter is connected to the DC rectifier 56 to reduce the voltage
from the voltage converter 60, for example dropping the voltage
down to 48 VDC or 12 VDC or to whatever voltage is suitable for the
LEDs 30 connected to the voltage converter 60. Depending on how the
LEDs are connected and configured, the voltage range could be from
roughly around 3 volts DC to greater than 100 volts DC.
[0073] Startup and feedback circuitry 62 in the conversion circuit
52 processes feedback signals 64 and 66, particularly during the
startup sequence, and provides control signals 70 to the protection
circuitry 54. The startup and feedback circuitry 62 controls the
protection circuitry 54 to protect the DC rectifier 56 and voltage
converter 60 by applying a load resistor in the protection
circuitry 54 to limit the voltage from the ballast 10, or to
control a switch to connect the DC rectifier 56 to the protection
circuitry 54, etc. The startup and feedback circuitry 62 is adapted
to meet the needs of the ballast 10 so that it appears that a
functional fluorescent tube is in place, as well as controlling the
protection circuitry 54 to protect the conversion circuit 52 from
damaging voltages, currents or frequencies.
[0074] Referring now to FIG. 6, an embodiment of a conversion
circuit 80 is disclosed for use in an LED replacement tube 22 for a
fluorescent lamp fixture having a magnetic ballast 10. In this
embodiment, the magnetic ballast 10 supplies an AC voltage 82.
Protection circuitry 84 is connected to the AC voltage 82 and
provides voltage, current and/or frequency protection to the
conversion circuit 80 from the magnetic ballast 10, as controlled
by control signals 86 from startup and feedback circuitry 90.
Although a magnetic ballast includes a starter that can supply high
voltages during startup, a magnetic ballast tends to operate at a
lower voltage than an electronic ballast. Furthermore, the magnetic
ballast typically does not include complex error sensing circuitry
that would require particular fluorescent tube simulation behaviors
from the LED replacement tube 22. The operating frequency of the
magnetic ballast is also much closer to that of the AC mains,
reducing or eliminating a need for frequency compensation. The
protection circuitry 84 thus may use lower voltage and slower
components if desired than the protection circuitry 54 of FIG.
5.
[0075] A DC rectifier 92 is connected to the protection circuitry
84 to produce a DC voltage, and a current controller 94 generates a
constant DC current for use by the LEDs 30. The current controller
94 may use any suitable circuit for generating a constant current.
The startup and feedback circuitry 90 processes feedback from the
output of the protection circuitry 84 and the LEDs 30, and as with
the protection circuitry 84, may use simpler and less robust
components than with an electronic ballast. The startup and
feedback circuitry 90 in one embodiment may be as simple as a
voltage divider and comparator to cause the protection circuitry 84
to disconnect from the DC rectifier 92 or to connect a resistor
across the ballast 10 as a current limiter, particularly during
startup or when the voltage otherwise rises. Simple startup
circuits can be applied depending on the characteristics of the
ballast 10 and, in some cases, the start-up circuit may not be
needed or may not be activated. This can also be true due to the
choice of components in the LED replacement tube 22 that are rated
to survive the highest voltage produced by the ballast 10.
[0076] Referring now to FIG. 7, another embodiment of a conversion
circuit 100 is powered by the AC output 82 of a magnetic ballast
10, with protection circuitry 84 controlled by startup and feedback
circuitry 90 as in FIG. 6. In this embodiment, power factor
correction circuitry 102 is connected between the protection
circuitry 84 and DC rectifier 92. The power factor correction
circuitry 102 compensates for the notoriously bad power factor of a
magnetic ballast 10. The power factor correction circuitry 102 also
functions if the magnetic ballast 10 is disconnected. The power
factor correction may be performed before DC rectification as well,
as in the conversion circuit 104 illustrated in FIG. 8. In this
embodiment, the power factor correction circuitry 102 is connected
to the output of the protection circuitry 84, and the DC rectifier
92 is connected to the output of the protection circuitry 84. The
startup and feedback circuitry 90 in this embodiment operates on
the output of the DC rectifier 92 and the LEDs 30 to control the
protection circuitry 84.
[0077] Referring now to FIG. 9, an embodiment of a conversion
circuit 120 that may be used in an LED replacement tube 22 for a
fluorescent lamp fixture having an electronic ballast 10 will be
described. The conversion circuit 120 is powered by the AC output
122 of the electronic ballast 10. Protection and cathode heater
circuitry 124 is connected to the AC output 122 to simulate a
cathode heater for the electronic ballast 10. During startup when
the electronic ballast 10 attempts to preheat the cathode of a
fluorescent tube, the protection and cathode heater circuitry 124
presents a load such as a resistor that is typical of a cathode in
the fluorescent tube being replaced. This load may be disconnected
after the startup sequence for efficiency. Any suitable circuitry
may be used in the protection and cathode heater circuitry 124 to
connect and disconnect the cathode simulation load, such as an RC
time constant or a timer circuit. Protective circuitry in the
protection and cathode heater circuitry 124 also protects the
conversion circuit 120 from excessive voltage using a device such
as a spark gap or a load applied when the voltage exceeds a
threshold value or to effectively perform such a function.
[0078] A high frequency DC rectifier 126 is connected to the
protection and cathode heater circuitry 124 to convert the high
frequency AC input to a DC voltage. The high frequency DC rectifier
126 uses, for example, ultrafast diodes to pass current from the
very high frequencies from the electronic ballast 10. A voltage
converter 130 is connected to the high frequency DC rectifier 126
to provide the proper DC voltage to the LEDs 30. Startup and
feedback circuitry 132 connected to the output of the protection
and cathode heater circuitry 124 and the LEDs 30 may also include
high speed electronics to be able to react to the high frequency
waveform from the protection and cathode heater circuitry 124.
[0079] Referring now to FIG. 10, an embodiment of a conversion
circuit 140 is disclosed for use in an LED replacement tube 22 for
a fluorescent lamp fixture having a magnetic or electronic ballast
10, in which a pulse generator 142 is used to control a current
through the LEDs 30. The conversion circuit 140 is powered by an AC
output 144 from the ballast 10. Protection and ballast handling
circuitry 146 is connected to the AC output 144 as with previous
embodiments, based on the type of ballast 10. A DC rectifier 150 is
connected to the protection and ballast handling circuitry 146 to
produce a DC voltage. The pulse generator 142 provides pulsed power
from the DC rectifier 150 to control a constant current driver 152
in a switching power supply technique. The constant current driver
152 supplies a constant current to the LEDs 30. Power factor and
constant current feedback circuitry 154 controls the timing and
width of pulses generated by the pulse generator 142, as well as
controlling the protection and ballast handling circuitry 146 as
described above.
[0080] Referring now to FIG. 11, an embodiment of a conversion
circuit 170 is disclosed for use in an LED replacement tube 22 for
a fluorescent lamp fixture in which the ballast 10 has been removed
or is otherwise bypassed or nonfunctional. The conversion circuit
170 is thus typically powered by a low voltage (in the range of
less than 100 V to greater than 500 V), low frequency AC mains
input 172. A DC rectifier 174 converts the AC input 172 to a DC
voltage. A pulse generator 176 controls a constant current driver
180 to power the LEDs 30. Constant current feedback 182 is used by
the pulse generator 176 to maintain a constant current from the
constant current driver 180. The pulse generator 176, constant
current driver 180 and constant current feedback 182 may be any
suitable switch mode power supply circuit to power the LEDs 30 in
the LED replacement tube 22 from a DC rectified AC mains input
172.
[0081] Referring now to FIG. 12, another embodiment of a conversion
circuit 170 is disclosed for use in an LED replacement tube 22 for
a fluorescent lamp fixture in which the ballast 10 has been removed
or is otherwise bypassed or nonfunctional. In this embodiment,
power factor correction is included in the constant current
feedback 184 to guarantee a good power factor from the pulse
generator 176 and constant current driver 180. Current overload and
thermal protection circuitry 190 is connected between the constant
current driver 180 and pulse generator 176 to reduce the width or
frequency of the pulses from the pulse generator 176 if the current
through the LEDs 30 exceeds a threshold value or if the temperature
of the conversion circuit 170 becomes excessive.
[0082] Referring now to FIG. 13, an embodiment of a conversion
circuit 200 is disclosed for use in an LED replacement tube 22 for
a fluorescent lamp fixture having a magnetic or electronic ballast
10, in which a pulse generator 202 and constant current driver 204
is used to control a current through the LEDs 30. The conversion
circuit 200 is powered by an AC output 206 from the ballast 10. DC
rectification and protection circuitry 210 is connected to the AC
output 210 to rectify the AC input and to protect the conversion
circuit 200 as with previous embodiments, based on the type of
ballast 10. The pulse generator 202 provides pulsed power from the
DC rectification and protection circuitry 210 to control the
constant current driver 204 in a switching power supply technique.
The constant current driver 204 supplies a constant current to the
LEDs 30, as controlled by constant current feedback and control
circuitry 208. Current overload and thermal protection circuitry
212 is connected between the constant current driver 180 and pulse
generator 176 to reduce the width or frequency of the pulses from
the pulse generator 176 if the current through the LEDs 30 exceeds
a threshold value or if the temperature of the conversion circuit
170 becomes excessive. Dimming sense and control circuitry 214 is
included in the conversion circuit 200 to enable dimming of the
LEDs 30. The dimming sense and control circuitry 214 can dim the
LEDs 30 by reducing the width or frequency of the pulses from the
pulse generator 176, or by causing a dimmable electronic ballast 10
to dim the AC output 206 of the ballast 10. The dimming sense and
control circuitry 214 may be controlled via a number of interfaces
as described above, including wired and wireless interfaces, such
as a digital addressable lighting interface (DALI), 0 to 10 V DC
analog, pulse width modulation (PWM), digital multiplexing (DMX),
etc. If the ballast 10 is dimmable, then it can perform the dimming
functions itself or the dimming sense and control circuitry 214 may
detect that the ballast 10 is attempting to dim, at which point the
dimming sense and control circuitry 214 would narrow the pulses to
dim the LEDs 30.
[0083] Referring now to FIG. 14, a more detailed block diagram of
an embodiment of a conversion circuit 230 is illustrated. An AC
input 232 powers the conversion circuit 230 through a fuse 234, an
electromagnetic interference (EMI) filter 236, a protection control
circuit 240 and a rectifier 242. Circuitry 244 for power factor
control, constant current generation, dimming and protection
control is included to perform the functions described above, again
with variations depending on the presence and type of ballast 10.
In this embodiment, a variable pulse generator 246 is driven by the
control circuitry 244, and the variable pulse generator 246
controls constant current drive circuitry including a switch 250
such as a power FET, an energy storage device such as an inductor
252, and diode 254. In this embodiment, the switching power supply
circuitry operates by pulling a current from an upper voltage rail
256 through the LEDs 30 and inductor 252 and switch 250 to a lower
voltage rail 260 when a pulse from the variable pulse generator 246
is on, powering the LEDs 30 and storing energy in the inductor 252.
When the pulse is off, the switch 250 is open, the inductor 252
resists the change in current and recirculates current through the
diode 254, the LEDs 30 and inductor 252. A capacitor 262 may be
connected in parallel with the LEDs 30 to smooth the voltage if
desired. A current sensing resistor 264 provides a feedback signal
266 to the control circuitry 244. The inductor 252 may be replaced
or augmented with a transformer and appropriate additional
components and/or circuits to provide the same functionality in an
isolated configuration (one example being in a flyback mode) and
also multiple output taps to control different LEDs (i.e., red,
green and blue LEDs) or configurations of LEDs (i.e., segments and
bank arrangements and configurations). A voltage divider 270 and
272 may be used to supply a reference voltage to the control
circuitry 244. The control circuitry 244 may be powered through a
resistor 274 from the upper voltage rail 256. The variable pulse
generator 246 may also be powered from the upper voltage rail 256
through a resistor 276. Current protection may be provided by a
sense resistor 280 providing feedback 282 to the variable pulse
generator 246. In this embodiment, the control circuitry 244 and
variable pulse generator 246 operate at different potentials, so
control signals from the control circuitry 244 to the variable
pulse generator 246 may pass through a level shifter 284. The
conversion circuit 230 used in a LED replacement tube 22 may be
variously embodied with any suitable output driver and control
circuitry, and is not limited to the specific examples set forth
above.
[0084] Referring now to FIG. 15, the various embodiments of the
conversion circuit 300 in an LED replacement tube 22 may drive the
LEDs 30 in an AC mode with a suitable voltage and frequency for
LEDs 30 connected in parallel and inverse fashion, that is, a
parallel array of LEDs arranged anode to cathode and cathode to
anode. Any of the various embodiments, both described herein and
otherwise, may be adapted to drive the LEDs 30 in AC mode, whether
in the presence of a magnetic or electronic ballast 10 or in the
absence of a ballast 10. For example, the conversion circuit 300
may be powered by an AC output 302 from a ballast 10. Protection
circuitry 304 may be connected to the AC output 302 as discussed
above to protect the conversion circuit 300. A voltage converter
306 may be used to adapt the level and frequency, as desired, from
the protection circuitry 304 to power the LEDs 30. Startup and
feedback circuitry 310 may be used in the conversion circuit 300 to
adapt to the ballast 10, if any, as described above.
[0085] Various embodiments of the LED replacement tube 22 may also
include multiple constant current sources if desired to drive, for
example, multiple load groups such as banks of different types or
colors of LEDs, etc. These embodiments can include any form(s) of
parallel/series back to back configurations of the LEDs. In
addition, for both AC and DC approaches, the embodiments and
implementations can be designed to produce constant current
output(s).
[0086] A method for powering an LED replacement tube in a
fluorescent lamp fixture is summarized in the flow chart of FIG.
16. The method includes receiving an AC voltage input from the
fluorescent lamp fixture (block 400), and converting the AC voltage
to a power source for at least one LED in the LED replacement tube,
wherein the converting is performed by a power converter in the LED
replacement tube (block 402). The method may further include
rectifying the AC voltage to a DC voltage before the converting,
and electrically simulating a fluorescent tube response to a
startup sequences from a ballast in the fluorescent lamp
fixture.
[0087] While illustrative embodiments have been described in detail
herein, it is to be understood that the concepts disclosed herein
may be otherwise variously embodied and employed. The
configuration, arrangement and type of components in the various
embodiments set forth herein are illustrative embodiments only and
should not be viewed as limiting or as encompassing all possible
variations that may be performed by one skilled in the art while
remaining within the scope of the claimed invention.
* * * * *