U.S. patent application number 09/162876 was filed with the patent office on 2001-11-29 for electronically controlled mechanical timepiece and method controlling the same.
Invention is credited to KOIKE, KUNIO, SHIMIZU, EISAKU, SHINKAWA, OSAMU, TAKAHASHI, OSAMU.
Application Number | 20010046188 09/162876 |
Document ID | / |
Family ID | 27311187 |
Filed Date | 2001-11-29 |
United States Patent
Application |
20010046188 |
Kind Code |
A1 |
KOIKE, KUNIO ; et
al. |
November 29, 2001 |
ELECTRONICALLY CONTROLLED MECHANICAL TIMEPIECE AND METHOD
CONTROLLING THE SAME
Abstract
An electronically controlled mechanical timepiece includes a
mechanical energy source; a generator for converting mechanical
energy transmitted through a train wheel to electrical energy. A
rotation controller coupled to the generator controls rotation of
the generator and includes switch capable of short circuiting the
generator by intermittently activating and deactivating the switch
using chopper control.
Inventors: |
KOIKE, KUNIO;
(MATSUMOTO-SHI, JP) ; SHIMIZU, EISAKU; (OKAYA-SHI,
JP) ; TAKAHASHI, OSAMU; (MATSUMOTO-SHI, JP) ;
SHINKAWA, OSAMU; (SUWA-SHI, JP) |
Correspondence
Address: |
STROOCK & STROOCK & LAVAN
180 MAIDEN LANE
NEW YORK
NY
100384982
|
Family ID: |
27311187 |
Appl. No.: |
09/162876 |
Filed: |
September 29, 1998 |
Current U.S.
Class: |
368/204 |
Current CPC
Class: |
G04C 10/00 20130101;
G04C 3/00 20130101; G04C 11/00 20130101 |
Class at
Publication: |
368/204 |
International
Class: |
G04B 001/00; G04C
003/00 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 30, 1997 |
JP |
9-265205 |
Apr 17, 1998 |
JP |
10-108251 |
Aug 4, 1998 |
JP |
10-220738 |
Claims
What is claimed is:
1. A timepiece, comprising: a mechanical energy source; a generator
having a rotor; a train wheel connecting said mechanical energy
source and said generator, said mechanical energy source driving
said train wheel to cause rotation of said generator, said
generator converting rotation into electrical power; and a rotation
controller coupled to said generator for controlling the rotation
of said generator, said rotation controller including a switch for
short-circuiting said generator, and wherein the rotation
controller chopper controls the rotation of said generator by
intermittently activating and deactivating said switch.
2. The timepiece of claim 1, wherein said generator includes a
rotor, said train wheel rotating said rotor, and the frequency of
chopper control is at least five times as large as the waveform
frequency of the voltage generated by said rotor of said generator
at a predetermined velocity.
3. The timepiece of claim 1, wherein the frequency of chopper
control is about five to one hundred times as large as the waveform
frequency of the voltage generated by said rotor of said generator
at a predetermined velocity.
4. The timepiece of claim 1, further comprising: a power supply
circuit having a first power supply line coupled to said generator
at a first terminal and a second power supply line coupled to said
generator at a second terminal for transmitting electrical energy
generated by said generator to said power supply circuit; and
wherein said switch includes a first switch and a second switch,
said first switch being interposed between said first terminal and
said first power supply line, said second switch being interposed
between said second terminal and said second power supply line; and
wherein said rotation controller continuously activates one of said
first switch and said second switch and chopper controls the other
of said first switch and said second switch.
5. The timepiece of claim 1, wherein said first switch includes a
first transistor and said second switch includes a third
transistor.
6. The timepiece of claim 5, wherein said rotation controller
includes: a comparison circuit for outputting a differential signal
based upon the comparison of a waveform-shaped signal with a time
reference signal; a signal output circuit for outputting a clock
signal having a variable pulse width based upon said differential
signal; a first logic circuit for receiving said clock signal and
said comparison reference signal and transmitting a signal to said
first transistor for selectively activating the first transistor;
and a second logic circuit for receiving said clock signal and said
comparison reference signal and transmitting a signal to said
second transistor for selectively activating the second
transistor.
7. The timepiece of claim 4, wherein said first transistor is a
field effect transistor having a gate connected to said second
terminal of said generator and said first switch further includes a
second field effect transistor connected in series to said first
field effect transistor, said second field effect transistor being
intermittently activated by said rotation controller; and said
third transistor is a field effect transistor having a gate
connected to said first terminal of said generator and said second
switch further including a fourth field effect transistor connected
in series to said third field effect transistor, said fourth field
effect transistor being intermittently activated by said rotation
controller.
8. The timepiece of claim 7, further comprises a first diode
interposed between said first terminal of said generator and one of
said first power supply line and second power supply line and a
second diode interposed between said second terminal of said
generator and the other of said first power supply line and said
second power supply line.
9. The timepiece of claim 7, further comprising a boost capacitor
interposed between one of said first generator terminal and said
second generator terminal and one of said first power supply line
and said second power supply line, and a diode interposed between
the other one of said first generator terminal and said second
generator terminal and the other one of said first power supply
line and said second power supply line.
10. The timepiece of claim 1, wherein said rotation controller
includes a chopper signal generator for generating at least a first
chopper signal and a second chopper signal, said first chopper
signal having a duty ratio different from said second chopper
signal, and transmitting said first chopper signal and said second
chopper signal to said switch, thereby performing chopper control
of said generator.
11. The timepiece of claim 10, wherein said rotation controller
includes a brake controller for controlling a brake activation,
said brake controller detecting the rotational cycle of said
generator and applying a brake on said generator based on said
rotational cycle, and for releasing the brake based on said
rotational cycle; said brake controller transmitting to said switch
said first chopper signal having a duty ratio larger than that of
said second chopper signal during said brake activation control and
transmitting said second chopper signal to said switch during said
brake deactivation control.
12. The timepiece of claim 1, wherein said rotation controller
includes a chopper signal generator for generating a chopper signal
and a brake controller for controlling a brake activation, said
brake controller detecting the rotational cycle of said generator
and applies a brake on said generator based on said rotational
cycle, and for releasing the brake based on said rotational cycle;
said brake controller transmitting to said switch said chopper
signal during said brake activation control.
13. The timepiece of claim 1, wherein said rotation controller
includes a chopper signal generator for generating at least a first
chopper signal and a second chopper signal, said first chopper
signal and said second chopper signal having different frequencies,
and transmitting said first chopper signal and said second chopper
signal to said switch to perform chopper control of said
generator.
14. The timepiece of claim 13, wherein said rotation controller
includes a brake controller for controlling a brake activation,
said brake controller detecting the rotational cycle of said
generator and applying a brake on said generator based on said
rotational cycle, and for releasing the brake based on said
rotational cycle; said brake controller transmitting to said switch
said first chopper signal having a frequency smaller than that of
said second chopper signal during said brake activation and
transmitting said second chopper signal to said switch during said
brake deactivation.
15. The timepiece of claim 14, wherein said first chopper signal
and said second chopper signal have different duty ratios.
16. The timepiece of claim 1, wherein said rotation controller
comprises: a chopper signal generator for generating at least a
first chopper signal having a first frequency and a second chopper
signal having a second frequency lower than said first frequency;
and a voltage sensing unit for detecting the voltage of a power
supply charged by the generator; and wherein, when the voltage of
the power supply detected by said voltage sensing unit is lower
than a predetermined value, a first chopper signal is transmitted
to said switch, and when the detected voltage of the power supply
is higher than the predetermined value, a second chopper signal is
transmitted to said switch, thereby chopper controlling the
generator.
17. The timepiece of claim 1, wherein said rotation controller
comprises: a chopper signal generator for generating a first
chopper signal having a first frequency and a second chopper signal
having a second frequency, said second frequency being lower than
said first frequency; a voltage sensor for detecting the voltage of
a power supply charged by said generator; a brake controller for
detecting the rotational cycle of said generator and applying a
brake on said generator when said rotational cycle is greater than
a first predetermined value, and for releasing the brake when said
rotational cycle is less than or equal to the first predetermined
value, and said brake controller transmitting said first chopper
signal to said switch when the detected voltage is greater than the
predetermined value, and said brake controller transmitting said
second chopper signal to said switch when the detected voltage is
less than or equal to the predetermined value, thereby performing
chopper control.
18. The timepiece of claim 1, wherein said rotation controller
includes a brake controller having a synchronizer for synchronizing
the time at which a brake is applied to said generator and at which
the brake is released from said generator, said synchronizer
controlling said switch by a chopper signal.
19. The timepiece of claim 1, wherein said rotation controller
includes a rotor rotation sensor for detecting the rotation of said
rotor comprising: a rotor sensor for detecting a rotor pulse
voltage; a comparator for comparing said rotor pulse voltage to a
reference voltage during a period of chopper control; and a pulse
generator for transmitting one of a low-level rotor rotation
sensing signal and a high-level rotor rotation sensing signal when
a said rotor pulse voltage exceeds said reference voltage and the
other of one of a low-level rotor rotation sensing signal and a
high-level rotor rotation sensing signal when said rotor pulse
voltage does not exceed said reference voltage.
20. The timepiece of claim 1, wherein said rotation controller
includes a rotor rotation sensor for detecting the rotation of said
rotor comprising: a rotor sensor for detecting a rotor pulse
voltage; a first counter for counting the number of consecutive
times a rotor pulse voltage is greater than a reference voltage
during a period of chopper control and storing a first count value;
a first comparator for comparing said first count value to a first
predetermined value; and a pulse generator for transmitting one of
a low-level rotor rotation sensing signal and a high-level rotor
rotation sensing signal when a first count exceeds said
predetermined value and the other of one of a low-level rotor
rotation sensing signal and a high-level rotor rotation sensing
signal when said first count does not exceed said predetermined
value.
21. The timepiece of claim 20, wherein said rotor rotation sensor
further comprises: a second counter for counting the number of
consecutive times a rotor pulse voltage is less than said reference
voltage and storing a second count value; a second comparator for
comparing said second count value to a second predetermined value;
and wherein said pulse generator transmits a low-level rotor
rotation sensing signal when said first count exceeds said first
predetermined value, and transmits a high-level rotor rotation
sensing signal when said second count exceeds said second
predetermined value.
22. The timepiece of claim 20, wherein said rotor rotation sensor
further comprises: a second counter for counting the number of
times a rotor pulse voltage is less than said reference voltage and
storing a second count value; a second comparator for comparing
said second count value to a second predetermined value; and
wherein said pulse generator transmits a low-level rotor rotation
sensing signal when said first count exceeds said first
predetermined value, and transmits a high-level rotor rotation
sensing signal when said second count exceeds said second
predetermined value.
23. The timepiece of claim 20, wherein said first predetermined
value is based on a chopping frequency and a noise frequency
superimposed on the rotational waveform of said rotor.
24. The timepiece of claim 21, wherein said first predetermined
value and said second predetermined value are based on a chopping
frequency and a noise frequency superimposed on the rotational
waveform of said rotor.
25. The timepiece of claim 22, wherein said first predetermined
value and said second predetermined value are based on a chopping
frequency and a noise frequency superimposed on the rotational
waveform of said rotor.
26. The timepiece of claim 1, wherein said rotation controller
controls includes a PLL control for controlling the rotation of
said rotor.
27. The timepiece of claim 1, wherein said rotation controller
includes an up/down counter for controlling the rotation of said
rotor.
28. A method of controlling a timepiece generator, comprising the
steps of: comparing a reference signal with a rotation sensing
signal that is based on the rotational cycle of said generator;
determining a phase difference between said reference signal and
said rotation sensing signal; and chopper controlling said
generator by intermittently activating and deactivating a switch
for short-circuiting the respective terminals of said generator in
accordance with said phase difference.
29. A method of controlling a timepiece generator, comprising the
steps of: inputting to an up/down counter a reference signal based
on a signal from a time standard source and a rotation sensing
signal based on the rotational cycle of the generator, wherein one
of said reference signal and said rotation signal is input as an
up-count signal and the other of said reference signal and said
rotation signal is input as a down-count signal; and chopper
controlling said generator by applying a brake to said generator
when the counter value of the up/down counter is a preset value and
not applying the brake to said generator when the counter value is
a value other than said preset value.
30. The method of controlling a timepiece generator of claim 28,
comprising the further step of: detecting a charged voltage of a
power supply; comparing said charged voltage with a prescribed
voltage; and outputting a system reset signal to said up/down
counter when said charged voltage is greater than said prescribed
voltage.
Description
BACKGROUND OF THE INVENTION
[0001] The present invention relates to an electronically
controlled mechanical timepiece for accurately driving hands fixed
to a train wheel by converting the mechanical energy of a
mechanical energy source, such as a mainspring, into electrical
energy by a generator and controlling the rotational cycle of the
generator by actuating a rotation controller powered by the
electric energy.
[0002] Japanese Examined Patent Publication No. 7-119812 and
Japanese Unexamined Patent Publication No. 8-101284 disclose
electronically controlled mechanical timepieces for displaying time
by driving hands fixed to a train wheel by converting mechanical
energy generated by the release of a mainspring into electrical
energy by a generator and controlling the value of the current
flowing to the coil of the generator by actuating a rotation
controller by the electrical energy.
[0003] In the timepieces of the above references, it is important
to increase braking torque when the mainspring has high torque and
prevent a drop of generated power at the same time to increase the
time with which the timepiece may be powered by the electrical
energy. For this purpose, the electronically controlled mechanical
timepiece disclosed in Japanese Examined Patent Publication No.
7-119812 provides an angular range where the rotating velocity of a
rotor is increased by turning off a brake to increase the amount of
generated power each time the rotor rotates. That is, a brake is
released during each rotation of the rotor to permit more power to
be generated to compensate for the drop in generated power when the
brake is applied over an angular range.
[0004] Further, the timepiece disclosed in Japanese Unexamined
Patent Publication No. 8-101284 increases braking torque and
prevents a drop of a generated voltage at the same time by boosting
the voltage of the power induced by a generator with a number of
stages of a boosting circuit.
[0005] However, in the timepiece disclosed in Japanese Examined
Patent Publication No. 7-119812, the rotor is switched from a state
in which it rotates at a high rotating velocity to a state in which
it rotates at a low rotating velocity. The abrupt velocity change
is difficult to realize as the rotor almost stops during each
rotation. In particular, because a fly wheel is typically provided
to increase the rotational stability of the rotor, it is difficult
to abruptly change the velocity of the rotor.
[0006] Further, since generated power is reduced when the brake is
applied, a limit is reached in suppressing the reduction in the
loss of generated power while increasing braking torque.
[0007] On the other hand, because the electronically controlled
mechanical timepiece disclosed in Japanese Unexamined Patent
Publication No. 8-101284 requires a number of switches and
capacitors, the cost of the design is increased.
[0008] Accordingly, it is desirable to provide a timepiece that
overcomes the drawbacks of the prior art.
SUMMARY OF THE INVENTION
[0009] Generally speaking, in accordance with the invention, an
electronically-controlled, mechanical timepiece preferably can
include a mechanical energy source, a generator driven by the
mechanical energy source coupled therewith through a train wheel.
The generator generating induced power and supplying electrical
energy from first and second terminals of the generator, and hands
coupled with the train wheel. A rotation controller, driven by the
electric energy can be provided to control the rotational cycle of
the generator, and can include a switch for short-circuiting the
respective terminals of the generator, and wherein the rotation
controller uses chopping to control the generator by intermittently
actuating the switch.
[0010] The electronically controlled mechanical timepiece of the
present invention drives the hands and the generator by a
mainspring and regulates the number of rotations of a rotor (and
thereby the rotation of the hands) by applying a brake to the
generator by the rotation controller. The generator rotation is
controlled by chopping the generator by activating and deactivating
the switch that short circuits the ends of the generator coil. When
the switch is activated, a short-circuit brake is applied to the
generator by chopping and energy is stored in the coil of the
generator. Whereas, when the switch is deactivated, the generator
is operated and a voltage generated thereby is increased by the
energy stored in the coil. As a result, when the generator is
controlled by chopping, a loss of generated power caused when the
brake is applied can be compensated by an increase in the generated
voltage when the switch is deactivated. Thus, brake torque can be
increased while keeping the generated power to at least a
prescribed level so that the timepiece can have a long life.
[0011] Since the effect of increasing the generated voltage is
diminished when the chopping frequency is lower than five times the
waveform frequency of the generated voltage, it is preferable that
a chopping frequency for intermittently activating the switch by
the rotation controller is at least five times as large as the
waveform frequency of the voltage generated by the rotor of the
generator at a set velocity. It is more preferable that the
chopping frequency is five to one hundred times as large as the
waveform frequency of the voltage generated by the rotor of the
generator at the set velocity.
[0012] When the chopping frequency is more than one hundred times
as large as the waveform frequency of the generated voltage, an IC
for executing chopping consumes a large amount of power. Thus, it
is preferable that the chopping frequency is one hundred times or
less the waveform frequency of the generated voltage. Further,
because the changing ratio of torque to the changing ratio of a
duty cycle approaches a prescribed level when the chopping
frequency is five times to one hundred times as large as the
waveform of the generated voltage, the control can be easily
carried out. However, the chopping frequency may be set to less
than five times or greater than one hundred times the value of the
generated voltage waveform depending upon the use and the control
method.
[0013] In a preferred embodiment, the timepiece includes first and
second power supply lines for charging the electrical energy of the
generator to a power supply circuit, wherein the switch is composed
of a first and a second switch, preferably transistors, interposed
between the first and second terminals of the generator and one of
the first and second power supply lines, respectively, and the
rotation controller continuously activates the switch connected to
one of the first and second terminals of the generator as well as
intermittently activates the switch connected to the other terminal
of the generator.
[0014] With this arrangement, since the control of the power
generating process and the rotation process of the generator can be
simultaneously carried out in addition to the brake control by
chopping, cost can be reduced by decreasing the number of parts as
well as an improvement can be attained in power-generating
efficiency by controlling the timing at which the respective
switches are activated.
[0015] Further, it is preferable that the rotation controller
includes comparators for comparing the waveforms of the voltage
generated by the generator with a reference waveform, a comparison
circuit for comparing the output from each comparator with a time
standard signal and outputting a difference signal, a signal output
circuit for outputting a pulse-width varied clock signal based on
the difference signal, and a logic circuit for ANDing the clock
signal and the output from each comparator and outputting an ANDed
signal to the transistors.
[0016] With this arrangement, because the power consumed to
intermittently control the transistors can be reduced, a circuit
may be arranged that is suitable for the generator of a clock that
generates a small amount of power.
[0017] A preferred embodiment of the timepiece includes a first
switch that includes a first field effect transistor having a gate
connected to the second terminal of the generator and a second
field effect transistor connected in series to the first field
effect transistor is intermittently activated by the rotation
controller. The second switch includes a third field effect
transistor having a gate connected to the first terminal of the
generator, and a fourth field effect transistor connected in series
to the third field effect transistor that is intermittently
activated by the rotation controller. Further, one of the first and
second diodes are interposed between one of the first and second
terminals of the generator and one of the first and second power
supply lines, respectively.
[0018] In another preferred embodiment, the first switch is
preferably composed of a first field effect transistor having a
gate connected to the second terminal of the generator that is a
second field effect transistor connected in series to the first
field effect transistor and intermittently activated by the
rotation controller. The second switch is preferably composed of a
third field effect transistor having a gate connected to the first
terminal of the generator and a fourth field effect transistor
connected in series to the third field effect transistor that is
intermittently activated by the rotation controller. A boost
capacitor is interposed between one of the first and second
terminals of the generator and the other of the first and second
power supply lines and a diode is interposed between the other of
the first and second terminals and the other of the first and
second power supply lines.
[0019] In the timepiece constructed as described above, when the
first terminal of the generator is positive and the second terminal
thereof is negative (i.e., the second terminal has lower potential
than that of the first terminal), the first field effect
transistor, whose gate is connected to the second terminal, is
activated, and the third field effect transistor, whose gate is
connected to the first terminal, is deactivated. As a result, the
a.c. current generated by the generator flows through the path
composed of the first terminal, the first field effect transistor,
one of the first and second power supply lines, the power supply
circuit, the other of the first and second power supply lines and
the second terminal.
[0020] When the second terminal of the generator is set to positive
and the first terminal thereof is set to negative (i.e., the first
terminal has a lower potential than that of the second terminal),
the third field effect transistor whose gate is connected to the
first terminal, is activated, and the first field effect
transistor, whose gate is connected to the second terminal, is
deactivated. As a result, the a.c. current generated by the
generator flows through the path composed of the second terminal,
the third field effect transistor, one of the first and second
power supply lines, the power supply circuit, the other of the
first and second power supply lines and the first terminal.
[0021] At that time, the second and fourth field effect transistors
are repeatedly activated and deactivated in response to the
chopping signals input to their gates. Since the second and fourth
field effect transistors are connected in series to the first and
third field effect transistors, when the first and third field
effect transistors are activated, a current flows regardless of the
activation state of the second and fourth field effect transistors.
However, when the first and third field effect transistors are
deactivated, current flows when the second and fourth field effect
transistors are activated in response to the chopper signal.
Therefore, when the second and fourth field effect transistors,
which are connected in series to one of the first and third field
effect transistors in the deactivated state, are activated in
response to the chopping signal, both the first and second switches
are activated to thereby short-circuit the respective terminals of
the generator.
[0022] With this operation, the generator may be subjected to a
brake control by chopping so that a drop of generated power when
the brake is applied can be compensated by an increase in the
generated voltage when the switch is deactivated. In this way,
brake torque can be increased, while maintaining generated power to
at least a prescribed level so that the life of the timepiece is
prolonged. Further, since the generator is rectified by the first
and third field effect transistors whose gates are connected to the
respective terminals, a comparator and the like are not required,
thereby simplifying the construction as well as preventing a drop
in the charging efficiency due to the power consumed by the
comparator. Further, since the field effect transistors are
activated and deactivated making use of the terminal voltage of the
generator, the respective field effect transistors can be
synchronized with the polarities of the terminals of the generator,
thereby improving the rectifying efficiency.
[0023] When a boost capacitor is interposed between one of the
terminals of the generator and a power supply line as described
above, the power supply circuit and the boost capacitor can be
simultaneously charged when the terminal voltage of the terminal to
which the capacitor is connected is increased. Whereas, when the
voltage of the other terminal of the generator is increased, the
power supply circuit can be charged with a high voltage obtained by
adding the voltage charged to the boost capacitor to the voltage
induced by the generator.
[0024] The rotation controller can include a chopper signal
generator for generating at least two types of chopper signals
having different duty ratios and at least the two types of chopper
signals can be imposed on the switch to thereby perform chopping
control of the generator.
[0025] In the present invention, when the switch for
short-circuiting both terminals of the generator is provided and
the generator is controlled by imposing the chopping signal to the
switch, although a lower chopper frequency and a higher duty ratio
can provide increased drive torque (brake torque) and the higher
chopper frequency increases the charged voltage (generated
voltage), the drive torque and voltage generated are not
significantly reduced even if the duty ratio is increased. This
effect is found where the charged voltage is increased until the
duty ratio is about 0.8 when the chopper frequency is at least 50
Hz. Thus, the generator can be controlled by chopping using at
least the two chopper signals having different duty ratios.
[0026] It is preferable that the rotation controller includes a
brake controller for detecting the rotational cycle of the
generator and applying a brake to the generator based on the
rotational cycle and a brake deactivation control for releasing the
brake. The brake controller imposes chopper signals having
different duty ratios on the switch in the brake-activation control
and the brake-deactivation control. For example, preferably, the
chopper signal imposed in the brake-activation control can have a
duty ratio larger than that of the chopper signal imposed in the
brake-deactivation control.
[0027] The timepiece of the present invention can drive the hands
and the generator by a mainspring and regulate the number of
revolutions of the rotor (and hence the hands) by applying a brake,
controlled by a rotation controller, to the generator.
[0028] The rotation control of the generator is carried out by
imposing a chopper signal on the switch capable of short-circuiting
both ends of the generator coil and turning the switch on and off,
that is, by chopping the switch. When the switch is activated by
the chopping, a short-circuit brake is applied to the generator and
energy is stored to the generator coil. Whereas, when the switch is
deactivated, the generator is operated and a voltage generated
thereby is increased by the energy stored in the coil. As a result,
when the generator is controlled by the chopping in the application
of the brake, a drop of the generated power caused when the brake
is applied can be compensated by an increase of the generated
voltage when the switch is deactivated. In this manner, brake
torque (brake torque) can be increased while preventing a drop in
the generated power so that the timepiece life is prolonged.
[0029] When the brake activation control in which the brake is
applied by imposing at least two types of chopper signals having
different duty ratios on the switch, the control torque of the
generator can be increased and a drop of the generated power can be
prevented by using a chopper signal having a large duty ratio
(during which the switch is activated for a longer period than the
switch is deactivated).
[0030] On the other hand, when the brake is released, the brake
torque of the generator can be greatly reduced and the generated
power can be sufficiently maintained by using a chopper signal
having a duty ratio smaller than that of the chopper signal
described above.
[0031] The application of the brake by a chopper signal having a
large duty ratio and the release thereof by means of the chopper
signal having a small duty ratio permits an increase of the brake
torque while suppressing a drop of the generated power (power
charged to a capacitor and the like), whereby an electronically
controlled mechanical timepiece having a long life can be
arranged.
[0032] Although the brake-activation control and the
brake-deactivation control are ordinarily carried out once in each
reference cycle of the generator (for example, the cycle during
which the rotor rotates once), in one embodiment, only the
brake-deactivation control may be carried out during a plurality of
the reference cycles just after the generator is started. Further,
although the duty ratio of the respective chopper signals may be
set in accordance with the characteristics of the generator to be
controlled, a chopper signal having a large duty ratio of, for
example, about 0.7 to 0.95, and a chopper signal having a small
duty ratio of about, for example, 0.1 to 0.3 can be used.
[0033] In another embodiment, the rotation controller includes a
chopper signal generator for generating a chopper signal and brake
controller for switching a brake-activation control for detecting
the rotational cycle of the generator and applying a brake to the
generator based on the rotational cycle and a brake-deactivation
control for releasing the brake. In this embodiment, the brake
controller imposes the chopper signal on the switch only in the
brake-activation control to thereby perform chopping control of the
generator.
[0034] Since the chopping signal is imposed only in the brake
activation control which, in this case, also needs to control a
brake, the brake torque of the generator can be increased and a
drop of generated power can be suppressed by chopping.
[0035] The rotation controller can include a chopper signal
generator for generating at least two types of chopper signals
having a different frequency, which are imposed on the switch to
thereby chopping control the generator.
[0036] It is preferable that the rotation controller includes a
brake controller for switching a brake activation control for
detecting the rotational cycle of the generator and applying a
brake to the generator based on the rotational cycle and a brake
deactivation control for releasing the brake, wherein the brake
controller uses chopper signals having different frequencies on the
switch in the brake activation control and the brake deactivation
control and the chopper signal imposed in the brake activation
control has a frequency smaller than that of the chopper signal
imposed in the brake deactivation control. When the chopper signal
imposed on the switch has a high frequency, the drive torque (brake
torque) is reduced so that a braking effect is decreased and the
charged voltage (generated voltage) is increased. On the other
hand, when the chopper signal having a low frequency is imposed,
the drive torque is increased, the braking effect is increased, and
the charged voltage is reduced as compared with the case where the
frequency is high. However, since chopping is carried out, the
charged voltage is increased as compared with a case where only a
brake control is executed.
[0037] Therefore, where the brake is applied during brake
activation control, the brake torque of the generator can be
increased by using a chopper signal having a low frequency while
suppressing a drop of the generated power by the chopping. On the
other hand, where the brake is released during brake-deactivation
control, the brake torque of the generator can be greatly reduced
by using a chopper signal having a frequency which is higher than
that used during brake activation control, thereby generating
sufficient power.
[0038] The brake torque can be increased while suppressing a drop
of the generated power by applying the brake using a chopper signal
having the low frequency and releasing the brake using a chopper
signal having the high frequency, whereby an electronically
controlled mechanical timepiece having a long life can be
arranged.
[0039] Although the frequency of the respective chopper signals may
be set in accordance with the characteristics of the generator to
be controlled, a chopper signal having a high frequency of, for
example, about 500-1000 Hz and a chopper signal having a low
frequency of, for example, about 10-100 Hz can be used.
[0040] Further, the chopping control may be carried out using
chopper signals having not only a different frequency but also a
different duty ratio. In particular, brake control can be
effectively carried out when a chopper signal having a low
frequency and a high duty ratio is used in the brake activation
control and a chopper signal having a high frequency and a low duty
ratio is used in the brake deactivation control.
[0041] The rotation controller can include a chopper signal
generator for generating at least two types of chopper signals
having different frequencies and a voltage sensor for detecting the
voltage of a power supply charged by the generator. Where the
voltage of the power supply detected by the voltage sensor is lower
than a set value, a chopper signal having a first frequency can be
imposed on the switch, and when the detected voltage of the power
supply is higher than the set value, a chopper signal having a
second frequency, which is lower than the first frequency, can be
imposed on the switch.
[0042] In one embodiment, the rotation controller preferably
includes a brake controller for switching a brake activation
control, for detecting the rotational cycle of the generator, and
for applying a brake to the generator based on the rotational
cycle, and a brake deactivation control for releasing the brake.
The chopper signal generator can generate two types of chopper
signals having a different duty ratio at first and second
frequencies. The brake controller can use chopper signals having
one of a first and second frequencies selected in correspondence to
the power supply voltage and a different duty ratio than the switch
in the brake activation control and the brake deactivation control,
respectively.
[0043] In the present invention arranged as described above, the
chopper signal for executing the brake control of the generator is
switched to a chopper signal having a different frequency in
accordance with the power supply voltage (for example, the voltage
charged to the capacitor by the generator). Accordingly, when the
power supply voltage is lower than a predetermined value, a chopper
signal can be used that decreases brake torque and increases
charged voltage (that is, which gives priority to charging rather
than a braking effect), whereas when the power supply voltage is
higher than the predetermined value, a chopper signal can be used
that increases the brake torque and decreases charged voltage (that
is, which gives priority to the brake rather than a charging
effect), so that a proper brake control can be carried out in
accordance with a charged state.
[0044] Further, it is preferable that the rotation controller
synchronizes the time at which the brake activation control for
applying the brake to the generator and the brake deactivation
control for releasing the brake are switched with a time when the
switch is intermittently activated in response to the chopper
signal. When the timing of the brake is synchronized with the
timing of the chopping signal, the chopper signal can also be used
as a pace measuring pulse.
[0045] In a further embodiment, the rotation controller can include
a rotational cycle sensing for detecting the rotational cycle of
the rotor by means of a rotor rotation sensing signal, which is set
to one of a low-level signal and a high-level signal when the
voltage of the rotational waveform of the generator is compared
with a reference voltage at a time of chopping and the voltage of
the rotational waveform is equal to or lower than the reference
voltage, and to the other of the low-level signal and the
high-level signal when the voltage of the rotational waveform is
higher than the reference voltage.
[0046] It is preferable that the rotation controller sets the rotor
rotation sensing signal to one of the low-level signal and the
high-level signal when the voltage of the rotational waveform of
the generator is compared with the reference voltage at the time of
chopping and is continuously equal to or lower than the reference
voltage n number of times, and sets the rotor rotation sensing
signal to the other of the low-level signal and the high-level
signal when the voltage of the rotational waveform of the generator
which is compared with the reference voltage at the time of
chopping is continuously higher than the reference voltage m number
of times. In addition, it is preferable that n and m are based on a
chopping frequency and a noise frequency superimposed on the
rotational waveform of the rotor.
[0047] When the generator is controlled by chopping, a chopper
pulse is superimposed on the rotational waveform of the rotor of
the generator. Therefore, the voltage of the rotational waveform of
the rotor is compared with the reference voltage at the time the
chopper pulse is superimposed (i.e., time at which the chopping is
executed) to obtain a rectangular wave signal (rotor rotation
sensing signal) that corresponds to the rotational cycle of the
rotor from the rotational waveform of the rotor.
[0048] At that time, noise such as an external magnetic field (for
example, a commercial power supply having a frequency of 50/60 Hz)
may be superimposed on the rotational waveform of the rotor and
there may arise such a case that the rotational waveform of the
rotor is deformed by the effect of the noise and the rotor rotation
sensing signal cannot be correctly obtained. To cope with this
problem, whether the rotational waveform of the rotor is equal to
or less than the reference voltage or greater than the reference
voltage can be correctly and reliably detected so that the
erroneous detection of the rotor rotation sensing signal caused by
the effect of the noise can be prevented by setting the rotor
rotation sensing signal to one of the low-level signal and the
high-level signal when the voltage of the rotational waveform of
the generator is continuously equal to or lower than the reference
voltage n number of times, and setting the rotor rotation sensing
signal to the other of the low-level signal and the high-level
signal when the voltage of the rotational waveform of the generator
(which is compared with the reference voltage at the time of
chopping) is continuously higher than the reference voltage m
number of times.
[0049] Further, the rotation controller may set the rotor rotation
sensing signal to one of the low-level signal and the high-level
signal when the voltage of the rotational waveform of the generator
(which is compared with the reference voltage at the time of
chopping) is continuously equal to or lower than the reference
voltage x number of times and set the rotor rotation sensing signal
to the other of the low-level signal and the high-level signal when
the rotational waveform of the generator (which is compared with
the reference voltage at the time of chopping) is higher than the
reference voltage y number of times (which may not be continuous).
It is preferable here that the x times and the y times are set
based on a chopping frequency and a noise frequency superimposed on
the rotational waveform of the rotor.
[0050] Whether the rotational waveform of the rotor is equal to or
less than the reference voltage or greater than the reference
signal can be correctly and reliably detected and the erroneous
detection of the rotor rotation sensing signal caused by the effect
of the noise can be prevented.
[0051] Further, the rotation controller may control the rotation of
the rotor using a PL control and may control the rotation of the
rotor using an up/down counter. In short, the rotation controller
may control the rotation of the rotor using any means so long as it
compares the rotational waveform of the rotor with the reference
waveform from a quartz oscillator and carries out the brake control
of the generator so as to reduce the difference therebetween.
[0052] A method of controlling an electronically controlled,
mechanical timepiece of the present invention is provided that
includes the steps of comparing a reference signal based on a
signal from a time standard source with a rotation sensing signal
output that corresponds to the rotational cycle of the generator,
intermittently activating a switch capable of short-circuiting the
respective terminals of the generator in accordance with an amount
of advance of the rotation sensing signal with respect to the
reference signal and subjecting the generator to a brake control by
chopping.
[0053] According to the above control method, because the rotation
control (brake control) of the generator is carried out by chopping
the activation and deactivation of the switch capable of
short-circuiting both the ends of the generator coil, a drop in
generated power caused when the brake is applied can be compensated
by an increase of the generated voltage when the switch is
deactivated. In this way, control torque can be increased while
keeping the generated power to at least a prescribed level so that
the life of an electronically controlled mechanical timepiece can
be prolonged.
[0054] A second method of controlling an electronically controlled
mechanical timepiece is provided, and includes the steps of
inputting a reference signal based on a signal from a time standard
source and a rotation sensing signal output that corresponds to the
rotational cycle of the generator to an up/down counter by setting
one of the signal as an up-count signal and the other of the
signals as a down-count signal, applying a brake to the generator
by chopping when the counter value of the up/down counter is a
predetermined value and not applying the brake to the generator
when the counter value is a value other than the predetermined
value.
[0055] According to the above control method, when the counter
value of the up/down counter is the predetermined value (that is,
when the torque of the mechanical energy source, such as a
mainspring, is increased and the rotation of the generator is
increased), a brake is continuously applied by chopping until the
difference between the respective count values disappears. As a
result, brake torque can be increased while keeping generated power
to at least a prescribed level, whereby a rotational velocity can
be promptly and correctly regulated so that a control can be
executed with excellent responsiveness. Further, since counting and
the comparison of respective count values can be performed at the
same time by the up/down counter, the construction can be
simplified and the difference between the respective count values
can be simply determined.
[0056] As described above, according to the electronically
controlled mechanical timepiece of the present invention, torque
for controlling the generator can be increased while keeping
generated power to at least a prescribed amount as well as a cost
can be also reduced.
[0057] An object of the present invention is to provide an
electronically controlled mechanical timepiece capable of
increasing the braking torque of a generator while keeping
generated power at least at a prescribed level, and reduce the cost
of the timepiece construction.
[0058] Other features of the present invention will become apparent
from the following detailed description, considered in conjunction
with the accompanying drawing figures. It is to be understood,
however, that the drawings, which are not to scale, are designed
solely for the purpose of illustration and not as a definition of
the limits of the invention, for which reference should be made to
the appended claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0059] In the drawing figures, which are not to scale, and which
are merely illustrative, and wherein like reference numerals depict
like elements throughout the several views:
[0060] FIG. 1 is a plan view showing a portion of an electronically
controlled mechanical timepiece constructed in accordance with a
first embodiment of the present invention;
[0061] FIG. 2 is a cross-sectional elevational view showing a
portion of the timepiece constructed in accordance with the first
embodiment of the invention;
[0062] FIG. 3 is a sectional elevational view showing a portion of
the timepiece constructed in accordance with the first embodiment
of the invention;
[0063] FIG. 4 is a block diagram the timepiece constructed in
accordance with the timepiece of the first embodiment of the
invention;
[0064] FIG. 5 is a block diagram showing the timepiece constructed
in accordance with the timepiece of the first embodiment of the
invention;
[0065] FIG. 6 is a circuit diagram showing a chopper charging
circuit of the timepiece constructed in accordance with the first
embodiment of the invention;
[0066] FIG. 7 is a block diagram of a waveform shaping circuit of
the timepiece constructed in accordance with the first embodiment
of the invention;
[0067] FIG. 8 a block diagram of a second embodiment of a waveform
shaping circuit of the timepiece constructed in accordance with the
first embodiment of the invention;
[0068] FIG. 9 is a waveform diagram of the timepiece constructed in
accordance with the first embodiment of the invention;
[0069] FIG. 10 is a timing chart showing processing executed by a
comparator of a brake control circuit of the timepiece constructed
in accordance with the first embodiment of the invention;
[0070] FIG. 11 is a flowchart showing a control method of the
timepiece constructed in accordance with the first embodiment of
the invention;
[0071] FIG. 12 is a timing chart of the timepiece constructed in
accordance with the first embodiment of the invention;
[0072] FIG. 13 is a block diagram showing an electronically
controlled mechanical timepiece constructed in accordance with a
second embodiment of the invention;
[0073] FIG. 14 is a circuit diagram of the timepiece constructed in
accordance with the second embodiment of the invention;
[0074] FIG. 15 is a circuit diagram of a rectifying circuit of the
timepiece constructed in accordance with the second embodiment of
the invention;
[0075] FIG. 16 is a timing chart for an up/down counter of the
timepiece constructed in accordance with the second embodiment of
the invention;
[0076] FIG. 17 is a timing chart of a chopper signal generating
unit of the timepiece constructed in accordance with a second
embodiment of the invention;
[0077] FIG. 18 is a diagram of an output waveform of a generator of
the timepiece constructed in accordance with the second embodiment
of the invention;
[0078] FIG. 19 is flowchart showing a control method of the
timepiece constructed in accordance with the second embodiment of
the invention;
[0079] FIG. 20 is a timing chart of the timepiece constructed in
accordance with the second embodiment of the invention;
[0080] FIG. 21 is a diagram of the operation of the timepiece
constructed in accordance with the second embodiment of the
invention;
[0081] FIG. 22 is a circuit diagram of a timepiece constructed in
accordance with a third embodiment of the invention;
[0082] FIG. 23 is a diagram of an output waveform of a generator of
the timepiece constructed in accordance with the third embodiment
of the invention;
[0083] FIG. 24 is a timing chart of the timepiece constructed in
accordance with the third embodiment of the invention;
[0084] FIG. 25 is a circuit diagram of a timepiece constructed in
accordance with a fourth embodiment of the invention;
[0085] FIG. 26 is a timing chart of the timepiece constructed in
accordance with the fourth embodiment of the invention;
[0086] FIG. 27 is a diagram of an output waveform of a generator of
the timepiece constructed in accordance with the fourth embodiment
of the invention;
[0087] FIG. 28 is a circuit diagram of a timepiece constructed in
accordance with a fifth embodiment of the invention;
[0088] FIG. 29 is a timing chart of a circuit of the timepiece
constructed in accordance with a fifth embodiment of the
invention;
[0089] FIG. 30 is a block diagram of the timepiece constructed in
accordance with the fifth embodiment of the invention;
[0090] FIG. 31 is a circuit diagram showing a second embodiment of
the chopper charging circuit constructed in accordance with the
invention;
[0091] FIG. 32 is a circuit diagram showing a third embodiment of
the chopper charging circuit constructed in accordance with the
invention;
[0092] FIG. 33 is a circuit diagram showing a fourth embodiment of
the chopper charging circuit constructed in accordance with the
invention;
[0093] FIG. 34 is a circuit diagram showing a fifth embodiment of
the chopper charging circuit constructed in accordance with the
invention;
[0094] FIG. 35 is a circuit diagram showing a sixth embodiment of
the chopper charging circuit constructed in accordance with the
invention;
[0095] FIG. 36 is a circuit diagram showing a seventh embodiment of
the chopper charging circuit constructed in accordance with the
present invention;
[0096] FIG. 37 is a view showing another embodiment of the waveform
shaping circuit constructed in accordance with the invention;
[0097] FIG. 38 is a circuit diagram showing another embodiment of
the chopper rectifying circuit constructed in accordance with the
invention;
[0098] FIG. 39 is a view showing another embodiment of a rotor
rotation sensing circuit constructed in accordance with the
invention;
[0099] FIG. 40 is a timing chart of the operation of the rotor
rotation sensing circuit of FIG. 39;
[0100] FIG. 41 is a graph of a waveform output by the rotor
rotation sensing circuit of FIG. 39;
[0101] FIG. 42 is a timing chart depicting the operation of another
embodiment of the rotor rotation sensing circuit constructed in
accordance with the invention;
[0102] FIG. 43 is a waveform output by the rotor rotation sensing
circuit of FIG. 42;
[0103] FIG. 44 is a circuit diagram showing a chopper charging
circuit of an experimental example of the present invention;
[0104] FIG. 45 is a graph showing the relationship between a
chopping frequency and a charged voltage in the experimental
example of the present invention; and
[0105] FIG. 46 is a graph showing the relationship between a
chopping frequency and braking torque in the experimental example
of the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0106] Referring to FIG. 1, a plan view showing a portion of an
electronically controlled, mechanical timepiece generally depicted
as 25, is constructed in accordance with of a first embodiment of
the invention. Referring to FIG. 2, which depicts timepiece 25 in a
front elevational cross section, timepiece 25 includes a movement
barrel 1, having a mainspring 1a, a barrel wheel 1b, a barrel arbor
1c, and a barrel cover 1d. Mainspring 1a is supported with its
outer end anchored at barrel wheel 1b and its inner end anchored at
barrel arbor 1c. Barrel arbor 1c is supported by a main plate 2 and
a train wheel support 3, and is rigidly secured to a ratchet wheel
4 by a ratchet wheel screw 5 so that both barrel arbor 1c and
ratchet wheel 4 are integrally rotated.
[0107] Referring again to FIG. 1, ratchet wheel 4 meshes with a
pawl 6 that permits ratchet wheel 4 to be rotated clockwise but
does not permit ratchet wheel 4 to be rotated counterclockwise. The
method of turning ratchet wheel 4 clockwise to tighten mainspring
1a is identical to the mechanism of self-winding or manual winding
of a mechanical timepiece, which is well-known in the art and
therefore is not discussed here. The rotation of barrel wheel 1b is
stepped up in speed by a factor of seven and transmitted to a
second wheel and pinion 7, and thereafter sequentially stepped up
by a factor of 6.4 and transmitted to a third wheel and pinion 8,
stepped up by a factor of 9.375 and transmitted to a fourth wheel
and pinion 9, stepped up by a factor of three and transmitted to a
fifth wheel and pinion 10, stepped up by a factor of 10 and
transmitted to a sixth wheel and pinion 11, stepped up by a factor
of ten and transmitted to a rotor 12. Through these step-up train
wheels 7 through 11, the rotational speed is increased by a factor
of 126,000.
[0108] Referring to FIG. 3, second wheel and pinion 7 includes a
cannon pinion 7a and a minute hand 13 attached to cannon pinion 7a
for indicating time. A second hand 14 for indicating time is
attached to the fourth wheel and pinion 9. To rotate second wheel
and pinion 7 at 1 rph and fourth wheel and pinion 9 at 1 rpm, rotor
12 may be controlled to rotate at 5 rps. In such a case, barrel
wheel 1b rotates at {fraction (1/7)} rph.
[0109] Timepiece 25 also includes a generator 20 having rotor 12, a
stator 15 and a coil block 16. Rotor 12 includes a rotor magnet
12a, a rotor pinion 12b, and a rotor flywheel 12c, which reduces
variations in the number of revolutions of rotor 12 due to
variations in driving torque of movement barrel 1. Stator 15
includes a stator body 15a around which a stator coil 15b having
40,000 turns, by way of example, is wound. Coil block 16 includes a
coil core 16a around which a coil 16b having 110,000 turns, by way
of example, is wound. Stator body 15a and coil core 16a are made of
PC Permalloy or of other materials known in the art. Stator coil
15b and coil 16b are connected in series so that the sum of the
voltages across these coils is output.
[0110] Next, a control circuit of the electronically controlled
mechanical timepiece will be described with reference to FIGS. 4 to
9. FIG. 4 is a block diagram showing a timepiece constructed in
accordance with a first embodiment of the invention.
[0111] The AC output from generator 20 is boosted and rectified
through a rectifying circuit 21, which executes boosting and
rectification using full wave rectification, half wave
rectification, transistor rectification, and the like. A load 22
such as an integrated circuit (IC) for controlling, for example, a
rotation controller, a quartz oscillator, and the like is connected
to rectifying circuit 21. FIG. 4 shows respective functional
circuits arranged in an IC separately from load 22 for the
convenience of description.
[0112] A voltage control oscillator (VCO) 25 coupled across
rectifying circuit 21 is composed of generator 20 and braking
circuit 23. Connected to generator 20 is a braking circuit 23.
Braking circuit 23 includes braking resistor 23A and an N-channel
or P-channel-type transistor 23B, which functions as a switch,
connected in series. A diode may be suitably inserted into braking
circuit 23 in addition to braking resistor 23A.
[0113] A rotation controller 50 is connected to VCO 25, and
includes an oscillating circuit 51 providing an input to a dividing
circuit 52 which provides an input to phase comparison circuit (PC)
54. A rotation sensing circuit 53, for detecting the rotation of
rotor 12 also provides an input to a phase comparison circuit (PC)
54 which in turn provides an input to a low pass filter (LPF) 55
which in turn provides an input to a brake control circuit 56.
[0114] Oscillating circuit 51 outputs an oscillating signal
generated by a quartz oscillator 51A, which is divided to a
prescribed frequency by dividing circuit 52. The divided signal is
output to phase comparison circuit 54 as a time standard signal (or
a reference frequency signal) fs of, for example, 100 Hz. Reference
frequency signal fs may be created using various types of reference
standard oscillation sources known to those skilled in the art in
place of quartz oscillator 51A.
[0115] Rotation sensing circuit 53 receives the output waveform
from VCO 25 at high impedance so that generator 20 is not affected
thereby, converts the output to a rectangular wave pulse fr and
outputs the same to phase comparison circuit 54. Phase comparison
circuit 54 compares the phase of time standard signal fs from
dividing circuit 52 with that of rectangular wave pulse fr from
rotation sensing circuit 53, calculates a difference and outputs a
difference signal. The difference signal is input to brake control
circuit 56 after its high frequency component is filtered by LPF
55. Brake control circuit 56 inputs the control signal from braking
circuit 23 to VCO 25 based on the above signal, by which a phase
synchronous control (PLL control) is realized.
[0116] Referring to FIG. 5, a more specific arrangement of the
embodiment is depicted. In the embodiment, a chopper charging
circuit 60 is used as braking circuit 23. As shown in FIG. 6,
chopper charging circuit 60 includes two comparators 61, 62
connected to coils 15b, 16b of generator 20. A power supply 63
supplies a comparison reference voltage Vref to comparators 61, 62,
OR circuits 64, 65 receive the outputs from comparators 61, 62 and
the clock output (control signal) from brake control circuit 56 and
output signals to the gates of transistors 66, 67 respectively.
Charging circuit 60 also includes the field effect transistors
(FETs) 66, 67, which are connected to coils 15b, 16b and function
as switches. Diodes 68, 69 are connected to coils 15b, 16b as well
as to a capacitor power supply lines. FETs 66, 67 are provided with
parasitic diodes 66A, 67A thereacross.
[0117] The positive side (first power supply line side) of
capacitor 21 a is set to a voltage VDD and the negative side
thereof (second power supply line side) is set to a voltage VTKN
(V/TANK/Negative) for example, the negative side of a battery.
Likewise, the negative side of power supply 63 and the source sides
of transistors 66, 67 are also set to the voltage VTKN (second
power supply line side). Therefore, chopper charging circuit 60
executes chopper boosting by short-circuiting generator 20 once to
the VTKN side by controlling transistors 66, 67 so that the voltage
of generator 20 is increased above voltage VDD when transistors 66,
67 are released. For this purpose, comparators 61, 62 compare a
generated and boosted voltage with the voltage Vref, which is
arbitrarily set between the VDD and the VTKN.
[0118] In chopper charging circuit 60, the outputs from comparators
61, 62 are also output to a waveform shaping circuit 70.
Accordingly, rotation sensing circuit 53 is composed of chopper
charging circuit 60 and waveform shaping circuit 70.
[0119] Waveform shaping circuit 70 may include a monostable
multivibrator 71 (preferably, a one-shot type) composed of a
capacitor 72 and a resistor 73, connected in parallel, as shown in
FIG. 7, or a type using a counter 74 and a latch 75 connected in
series as shown in FIG. 8. An OR Gate receives the count of counter
74 and provides an ORed input to counter 74.
[0120] Referring to FIG. 5, Phase comparison circuit 54 includes an
analog phase comparator (not shown), a digital phase comparator
(not shown), and may include a CMOS type phase comparator using a
CMOS IC. Phase comparison circuit 54 detects a phase difference
between the time standard signal fs of 10 Hz output from dividing
circuit 52 and the rectangular wave pulse fr output from waveform
shaping circuit 70 and outputs a difference signal fd.
[0121] Difference signal fd is input to a charge pump (CP) 80,
where it is converted into a voltage level. A high frequency
component of difference signal fd is removed by a loop filter 81
composed of a resistor 82 and a capacitor 83. Therefore, LPF 55
shown in FIG. 4 is composed of charge pump 80 and loop filter
81.
[0122] Referring again to FIG. 5, the level signal a output from
loop filter 81 is input to a signal output circuit 90. A triangular
signal b, obtained by converting the signal from oscillating
circuit 51 through a triangular wave generating circuit 92, which
uses a dividing circuit 91 for dividing the signal from oscillating
circuit 51 to 50 Hz-100 kHz, or an integrator, for example, is also
input to signal output circuit 90. Signal output circuit 90 outputs
a rectangular wave pulse signal c in response to level signal a
from loop filter 81 and triangular signal b. Therefore, brake
control circuit 56, depicted in FIG. 4, includes signal output
circuit 90, dividing circuit 91 and triangular wave generating
circuit 92.
[0123] Rectangular wave pulse signal c output from signal output
circuit 90 is input to chopper charging circuit 60 as clock signal
CLK.
[0124] An operation of the embodiment is described with reference
to the waveforms shown in FIGS. 9, 10 and the flowchart of FIG.
11.
[0125] When rotor 12 of generator 20 is rotated by mainspring 1a,
alternating current waveforms are output from coils 15b, 16b in
accordance with the change of fluxes. The waveforms are input to
comparators 61, 62, which compare them with reference voltage Vref
from power supply 63. A timing of polarity for activating
transistors 66, 67 is detected by the comparison executed by
comparators 61, 62.
[0126] That is, boosting and charging to capacitor 21a and a
chopper braking operation of generator 20 can be carried out only
by inputting the clock signal CLK to the gates of transistors 66,
67. However, because transistors 66,67 are controlled solely by
clock signal CLK, when clock signal CLK is set to a high-level
signal, transistors 66, 67 are simultaneously activated and
short-circuited, whereas when clock signal CLK is set to a
low-level signal, capacitor 21a is charged through one of parasitic
diodes 66A, 67A and one of diodes 68, 69. More specifically, when a
terminal AG1 is set to a positive level, capacitor 21a is charged
through a path from parasitic diode 67A to diode 68 through coils
15b, 16b, whereas when a terminal AG2 is set to a positive level,
capacitor 21a is charged through a path from parasitic diode 66A to
diode 69 through coils 15b, 16b.
[0127] In this case, since the two diodes are connected in series
in the charging path, a voltage is dropped by an amount obtained by
adding the rising-up voltages VF of the respective diodes.
Therefore, capacitor 21a cannot be charged unless a charging
voltage is higher than a voltage obtained by adding the amount of
the voltage drop to the potential of capacitor 21a, which is a
large factor for lowering a charging efficiency in a generator used
in an electronically controlled mechanical timepiece that generates
a small voltage.
[0128] To cope with the above problem, the embodiment improves the
charging efficiency by regulating the timing of transistors 66, 67
without simultaneously activating and deactivating them. That is,
when terminal AG1 is set to positive when viewed from voltage VTKN
and exceeds voltage Vref, comparator 62 outputs a high-level signal
so that OR circuit 65 continuously outputs a high-level signal
regardless of clock signal CLK, and transistor 67 is activated by a
voltage applied to its gate.
[0129] On the other hand, comparator 61 connected to terminal AG2
outputs a low-level signal due to terminal AG2 being less than
voltage Vref, OR circuit 64 outputs a signal that is synchronized
with clock signal CLK, transistor 66 repeats an
activation/deactivation operation and terminal AG1 is chopper
boosted.
[0130] The charging path at the time is set to AG1-diode
68-capacitor 21a -VTKN transistor 67 (from source to drain)-AG2.
Parasitic diode 67A is removed from the path when transistor 66 is
activated once and then deactivated, thereby reducing a voltage
drop and improving the charging efficiency.
[0131] It is preferable to select, as the level of voltage Vref, a
generated voltage level that permits the voltage generated by
generator 20 to be chopper boosted and charged to capacitor 21a.
Ordinarily, voltage Vref is set to a level exceeding voltage VTKN
by several hundred millivolts. When voltage Vref is set to a
high-level, the power-generating efficiency is lowered accordingly
because the period within which comparators 61, 62 are put into
operation is increased and diodes 66A and 67A are connected in
series in a charging path during the period, whereby the
power-generating efficiency is lowered.
[0132] When transistor 66 is activated, generator 20 is
short-circuited because transistor 67 is also activated at the
time. As a result, a short-circuit brake is applied to generator 20
and the amount of power generated is reduced accordingly. However,
the voltage of generator 20 can be boosted to a level higher than
VDD by short-circuiting generator 20 to the voltage VTKN side when
transistor 66 is released. Therefore, when a chopping cycle for
activating and deactivating transistors 66, 67 is set higher than a
prescribed cycle, a drop in generated power can be compensated for
when a short-circuit brake is applied so that brake torque can be
increased while maintaining generated power to a level higher than
a prescribed level.
[0133] When the output from generator 20 is set to the terminal AG2
side, an operation similar to the aforesaid operation is carried
out except that the operations of comparator 61 and transistor 66
are replaced with those of comparator 62 and transistor 67.
[0134] The outputs from comparators 61, 62 of chopper charging
circuit 60 are input to waveform shaping circuit 70 and converted
into rectangular wave pulse fr. That is, rotation sensing circuit
53 composed of chopper charging circuit 60 and waveform shaping
circuit 70 detects the rotation of rotor 12 and outputs it as the
rectangular wave pulse fr (Step 1) (hereinafter, step is
abbreviated as "S"; see FIG. 11).
[0135] For example, monostable multivibrator 71 shown in FIG. 7
executes waveform shaping by detecting only one polarity (i.e., the
output from comparator 62). More specifically, monostable
multivibrator 71 is triggered in response to the rising-up edge of
output from comparator 62 and outputs a pulse having a length set
by values of a capacitor and resistor (RC). Since the RC has a time
constant set about 1.5 times the cycle of clock signal CLK, the
rising-up edge of the next output of comparator 62 is input within
the pulse time set by the RC to thereby trigger monostable
multivibrator 71. Therefore, monostable multivibrator 71
continuously outputs a high-level signal until the ascending edge
of the output from comparator 62 is not generated within the time
1.5 T set by the RC so that the rectangular wave pulse fr
corresponding to the output signal of generator 20 is output.
However, the descent time of the pulse fr is delayed by the time of
the high-level of the set-time-polarity-detecting pulse of the RC.
Thus, when the RC is set to 1.5 T as shown in FIG. 9, a delay of 1
T (=1.5 T-0.5 T) is caused.
[0136] On the other hand, waveform shaping circuit 70 shown in FIG.
8 also executes waveform shaping by detecting only one polarity
(i.e., the output of one of comparators 61, 62). More specifically,
in this embodiment, waveform shaping circuit 70 is composed of
counter 74 for counting the clock signal for only a time 2 T and
clearing it, and latch 75 for applying a latch in response to the
output from counter 74. Counter 74 and latch 75 are set so that
they are cleared in response to the output from either comparator
61, 62. For example, where output is generated from comparator 62,
latch 75 and counter 74 are cleared and output fr outputs a
low-level signal as shown in FIG. 9. When output is not generated
from comparator 62, output fr is latched to a high-level by counter
74.
[0137] When output is generated from comparator 62 again, a latch
signal is cleared and output fr is dropped to a low-level signal so
that the rectangular wave pulse can be obtained. When the output is
generated from comparator 62 within the time (2 T) set to the
counter, no latch operation is executed. In this case, as shown in
FIG. 9, the rise of rectangular wave pulse fr to a high-level is
also delayed by the time (2 T) set to counter 74.
[0138] Respective waveform shaping circuits 70 shown in FIGS. 7 and
8 convert the output from comparator 62 into a rectangular wave
pulse by adding a delay to the output. This delay is executed to
prevent the occurrence of incorrect pulse by the time set to the RC
or the time set to the counter because the output from comparator
62 at the start of the system is not always obtained as a signal
synchronized with the cycle of the clock signal and sometimes
exhibits itself as an output with lack of pulse. Such an occurrence
causes incorrect pulses when the output is converted into a
rectangular wave pulse. The times set to the RC and the counter may
be set to about 1.5-5 T in accordance with the degree of the lack
of pulse. The delay does not have any affect on control.
[0139] The rectangular wave pulse fr shaped as described above is
compared with the time standard signal fs of dividing circuit 52 by
phase comparison circuit 54 (S2) and difference signal fd thereof
is converted into level signal a through charge pump 80 and loop
filter 81.
[0140] Signal output circuit 90 outputs a rectangular wave pulse
signal c in response to level signal a and triangular signal b from
triangular wave generating circuit 92 as shown in FIG. 10. Level
signal a is set such that when rectangular wave pulse fr based on
the rotation of rotor 12 advances with respect to time standard
signal fs, pulse fr is made lower than the standard level, whereas
if pulse fr delays with respect to time standard signal fs and
pulse fr is made higher than the standard level.
[0141] As a result, when rectangular wave pulse fr advances with
respect to time standard signal fs (S3), rectangular wave pulse
signal c is in a high-level state for a longer time to thereby
increase a short-circuit brake period in the respective chopper
cycles in chopper charging circuit 60 so that the amount of braking
is increased and the velocity of rotor 12 of generator 20 is
reduced (S4). On the contrary, when rectangular wave pulse fr is
delayed with respect to time standard signal fs, rectangular wave
pulse signal c is in a low-level state for a longer time to thereby
decrease the short-circuit brake period in the respective chopper
cycles in chopper charging circuit 60 so that the amount of brake
is decreased and the velocity of rotor 12 of generator 20 is
increased (S5). Rectangular wave pulse fr is controlled by the
repetition of the above brake control until pulse fr corresponds to
time standard signal fs.
[0142] The relationship between time standard signal fs and
rectangular wave pulse fr from waveform shaping circuit 70 shown in
FIGS. 4 and 5 and signal c output from signal output circuit 90 can
be represented by a timing chart as shown in FIG. 12. That is,
output signal c from signal output circuit 90 is arranged such that
the short-circuit brake period is increased to thereby increase the
amount of brake or decreased to thereby reduce the amount of brake
in accordance with the phase difference between time standard
signal fs and rectangular wave pulse fr. That is, in the comparison
of cycles T1, T2 and T3 of time standard signal fs shown in FIG.
12, because the phase difference between the descending edge of
rectangular wave pulse fr and that of the subsequent reference
frequency signal fs in cycle T2 is smaller than the phase
difference in cycle T1, output signal c from signal output circuit
90 in the next cycle (cycle T3) following the previous cycle T2 is
set to decrease the short-circuit brake period to thereby reduce
the amount of brake as compared with the case where the phase
difference between the descending edge of rectangular wave pulse fr
is compared with that of the subsequent reference frequency signal
fs in cycle T1 (that is, as compared with cycle T2). Output signal
c is set to the same waveform over one cycle of time standard
signal fs; that is, signal c has a waveform having the same
short-circuit brake period. In a preferred embodiment, the brake
period is set to a high-level so that a brake is applied when
output signal c is at the high-level.
[0143] This embodiment can provide the following benefit:
[0144] (1) Since VCO 25, composed of generator 20 and brake circuit
23, phase comparison circuit 54 and brake control circuit 56 are
provided, the rotation of generator 20 can be controlled by the PLL
control. As a result, since a brake level can be set in braking
circuit 23 by comparing the waveforms of generated power at
respective cycles, once generator 20 is in a lock range, it can be
stably controlled with prompt responsiveness unless the waveforms
of generated power greatly vary at a moment.
[0145] (2) Since braking circuit 23 is composed of chopper charging
circuit 60 and brake control is realized using chopping, control
torque can be increased while keeping a generated power to at least
a prescribed level. As a result, the brake control can be
effectively executed while maintaining the stability of the
system.
[0146] (3) Since chopper charging circuit 60 is used, not only for
brake control but also to charge capacitor 21a through rectifying
circuit 21, chopper charging circuit 60 can detect the rotation of
rotor 12 of generator 20. Therefore, the circuit can be simplified,
the cost of such a system can be reduced by decreasing the number
of parts, and manufacturing efficiency can be improved as compared
with a case where these respective functions are performed by
individual circuits.
[0147] (4) Since chopper charging circuit 60 controls the timing at
which transistors 66, 67 are activated and deactivated and
activates and deactivates one of transistors 66, 67 when the other
thereof is continuously activated, a voltage drop in the charging
path can be reduced and power generating efficiency can be
improved. Such a system is very effective in improving the power
generating efficiency of generator 20, which is small in size.
[0148] (5) Since waveform shaping circuit 70 is provided, even if
the output waveform from VCO 25 is changed by changing the circuit
arrangement of chopper charging circuit 60, for example, a
different portion of the output waveform can be absorbed by
waveform shaping circuit 70. As a result, even if the circuit
arrangement of chopper charging circuit 60 is different, rotation
controller 50 can be commonly used so that a cost reduction for
parts is realized.
[0149] (6) When an ordinary circuit made by combining a low pass
filter (LPF) and a comparator is used as waveform shaping circuit
70, a portion of a generated voltage, which has been chopper
boosted, is charged to an LPF composed of a primary delay RC filter
and the like. Although this lowers the charging efficiency to
capacitor 21a, since respective waveform shaping circuits 70 of the
embodiment carry out processing digitally, a consumption current
can be suppressed to a low-level and the charging efficiency to
capacitor 21a can be improved.
[0150] Next, a timepiece constructed in accordance with a second
embodiment of the invention will be described, wherein the same
numerals as used in the aforesaid embodiment are used to denote
components that are similar or correspond to those of the aforesaid
embodiment, permitting the description thereof to be omitted or
simplified.
[0151] Referring to FIG. 13, an electronically controlled
mechanical timepiece includes a mainspring 1 a as a mechanical
energy source, a velocity increasing train wheel (wheels 7-11)
transmits the torque of mainspring 1a to generator 20 and hands
(minute hand 13 and second hand 14) coupled with the velocity
increasing train wheel for displaying a time.
[0152] Generator 20 is driven by mainspring 1a through the velocity
increasing train wheel and supplies electric energy by induction.
The a.c. output from generator 20 is boosted and rectified through
rectifying circuit 21, which executes boosting and rectification of
the output using, for example, full wave rectification, half wave
rectification and transistor rectification, and charges the output
to a power supply circuit 21a, which includes a capacitor.
[0153] As shown in FIG. 14, in this embodiment, generator 20 is
provided with a brake circuit 120, which includes a rectifying
circuit 35. More specifically, brake circuit 120 includes first and
second switches 121, 122 for applying a short circuit brake to
generator 20 by short-circuiting the output terminals of generator
20, denominated as a first terminal MG1 and a second terminal
MG2.
[0154] First switch 121 includes a first-channel field effect
transistor (FET) 126, having a gate connected to second terminal
MG2, and a second field effect transistor 127, having a gate to
which a chopper signal (chopper pulse) CH3 from a chopper signal
generator 180 (to be described later) is input. First FET 126 is
connected in series to second FET 127.
[0155] Second switch 122 is composed of a third P-channel FET 128,
having a gate connected to first terminal MG1, and a fourth FET
129, having a gate to which chopper signal CH3 from chopper signal
generator 180 is input. Third FET 128 is connected in series to
fourth FET 129.
[0156] A voltage doubler rectifying circuit (or simplified
synchronously boosting chopper rectifying circuit) 35 is composed
of a boost capacitor 123, diodes 124, 125, and first switch 121 and
second switch 122, which are connected to generator 20. Any type of
one-direction devices for permitting a current to flow in one
direction known to those skilled in the art may be used as diodes
124, 125. In particular, because the voltage generated by generator
20 is small in an electronically controlled mechanical timepiece,
it is preferable to use a Schottky barrier diode having a small
voltage drop Vf as diode 125. Further, diode 124 is preferably a
silicon diode having a small inverse leak voltage.
[0157] Brake circuit 120 is controlled by rotation controller 50,
which is driven by the power supplied from power supply circuit
(capacitor) 21a. As shown in FIG. 13, rotation controller 50
includes oscillating circuit 51, rotation sensing circuit 53 and
brake control circuit 56.
[0158] Oscillating circuit 51 outputs an oscillating signal (32768
Hz) using quartz oscillator 51A as a time standard source. The
oscillating signal is divided to a prescribed frequency by a
dividing circuit 52 composed of a twelve-stage flip-flop. The
twelfth-stage output Q12 of dividing circuit 52 is output as a
reference signal of 8 Hz.
[0159] Rotation sensing circuit 53 is composed of a waveform
shaping circuit 161, which is connected to generator 20 and
mono-multivibrator 162. Waveform shaping circuit 161 is composed of
an amplifier and a comparator and converts a sine wave into a
rectangular wave. Mono-multivibrator 162 functions as a band-pass
filter for passing a pulse having at least a certain frequency and
outputs a rotation sensing signal FG1 from which noise is
filtered.
[0160] Brake control circuit 56 includes an up/down counter 160,
which functions as a brake control circuit, synchronous circuit 170
and chopper signal generator 180. Rotation sensing signal FG1 from
rotation sensing circuit 53 and reference signal fs from dividing
circuit 52 are input to the up-count input terminal and the
down-count input terminal of up/down counter 160 through
synchronous circuit 170.
[0161] Synchronous circuit 170 is composed of four flip-flops 171,
AND gates 172 and NAND gates 173, and synchronizes rotation sensing
signal FG1 with reference signal fs (8 Hz) making use of output Q5
(1024 Hz) from the fifth stage of dividing circuit 52 and output Q6
(512 Hz) from the sixth stage of dividing circuit 52. In addition,
synchronous circuit 170 adjusts the respective signal pulses to
prevent them from being output in a superimposed state.
[0162] Up/down counter 160 is composed of a four-bit counter. A
signal based on rotation sensing signal FG1 is input to the
up-count input terminal of up/down counter 160 from synchronous
circuit 170 and a signal based on reference signal fs is input to
the down-count input terminal thereof from synchronous circuit 170.
With this operation, reference signal fs and rotation sensing
signal FG1 are counted and the difference therebetween is
calculated at the same time.
[0163] Up/down counter 160 includes four data input terminals
(preset terminals) A-D. A high-level signal is input to terminals
A-C so that the initial value (preset value) of up/down counter 160
is set to a counter value 7.
[0164] An initializing circuit 190 is connected to the LOAD input
terminal of up/down counter 160 for outputting a system reset
signal SR in accordance with the voltage of power supply circuit
21a. Initializing circuit 190 outputs a high-level signal until the
charged voltage of power supply circuit 21a becomes a prescribed
voltage at which point it outputs a low-level signal.
[0165] Since up/down counter 160 does not receive an up-down input
until the LOAD input terminal is a low-level signal, that is, until
the system reset signal SR is output, the counter value of up/down
counter 160 is maintained at "7".
[0166] Up/down counter 160 has four-bit output terminals QA-QD. The
fourth bit output terminal QD, which is connected to chopper signal
generator 180, outputs a low-level signal when the counter value is
7 or less, and outputs a high-level signal when the counter value
is 8 or more.
[0167] Chopper signal generator 180 includes a first chopper signal
generator 181, which includes three AND gates 182, 183 and 184, and
which outputs a first chopper signal CHI and uses outputs Q5-Q8 of
dividing circuit 52, a second chopper signal generator 185, which
includes two OR gates 186, 187, and which outputs a second chopper
signal CH2 and uses outputs Q5-Q8 of dividing circuit 52, an AND
gate 188 to which the output QD of up/down counter 160 and signal
CH2 of second chopper signal generator 185 are input, and a NOR
gate 189 to which the output of AND gate 188 and signal CH1 of
first chopper signal generator 181 are input.
[0168] The output CH3 from NOR gate 189 of chopper signal generator
180 is input to the gates of second and fourth FETs 127, 129.
Therefore, when a low-level signal is output from output CH3,
transistors 127, 129 are activated causing generator 20 to be
short-circuited, thereby applying a brake. On the other hand, when
a high-level signal is output from output CH3, transistors 127, 129
are deactivated and no brake is applied to generator 20. In this
manner, generator 20 can be chopper-controlled by the chopper
signal from output CH3.
[0169] Next, an operation of the embodiment will be described with
reference to the timing charts of FIGS. 16-18 and the flowchart of
FIG. 19, which depicts steps S11-S15.
[0170] When generator 20 starts to operate and a low-level system
reset signal SR is input from initializing circuit 190 to the LOAD
input terminal of up/down counter 160 (S1), an up-count signal (UP)
based on rotation sensing signal FG1 and a down-count signal (DOWN)
based on reference signal fs are counted by up/down counter 160
(S12). These signals are set by synchronous circuit 170 such that
they are not simultaneously input to up/down counter 160.
[0171] As a result, when up-count signal (UP) is input where the
initial count value is set to "7", the counter value increases to
"8" and a high-level signal is output from the output QD to AND
gate 188 of chopper signal generator 180. On the other hand, when a
down-count signal (DOWN) is input and the counter value returns to
"7", the low-level signal is output from the output QD.
[0172] As shown in FIG. 17, in chopper signal generator 180, output
CHI is output from first chopper signal generator 181 and output
CH2 is output from second chopper signal generator 185 making use
of the outputs Q5-Q8 of dividing circuit 52.
[0173] When the low-level signal is output from the output terminal
QD of up/down counter 160 (count value is "7" or less), since the
output from AND gate 188 becomes a low-level signal, output CH3
from NOR gate 189 becomes a chopper signal obtained by inverting
output CH1. That is, a chopper signal having a small duty ratio
(the ratio at which transistors 127, 129 are activated) at which a
high-level signal (brake-deactivation time) is long and a low-level
signal (brake-activation time) is short. Therefore, the
brake-activation time is reduced at a reference cycle so that
almost no brake is applied to generator 20. Accordingly, under this
circumstance, the brake-deactivation control gives priority to
power generation (S13, S15).
[0174] On the other hand, when the high-level signal is output from
output terminal QD of up/down counter 160 (count value is "8" or
more), since the output from AND gate 188 becomes a high-level
signal, output CH3 from NOR gate 189 becomes a chopper signal
obtained by inverting output CH2, and has a large duty ratio at
which a low-level signal (brake-activation time) is long and a
high-level signal (brake-deactivation time) is short. Therefore,
the brake-activation time is increased at the reference cycle and
the brake-activation control is performed on generator 20. However,
because the brake is deactivated at a prescribed cycle, a chopping
control is carried out so that brake torque can be improved while
suppressing the drop of generated power (S13, S14).
[0175] Voltage doubler rectifying circuit (or simplified
synchronously boosting chopper rectifying circuit) 35 charges the
electric charge generated by generator 20 to power supply circuit
21a as described below. That is, when the polarity of the first
terminal MG1 is positive and the polarity of the second terminal
MG2 is negative, first FET 126 is activated and third FET 128 is
deactivated. As a result, the electric charge of the voltage
induced by generator 20 is charged to capacitor 123 of, for
example, 0.1 .mu.F through the circuit "{circle over
(4)}.fwdarw.{circle over (3)}.fwdarw.{circle over
(7)}.fwdarw.{circle over (4)}" shown in FIG. 15, as well as to
power supply circuit (capacitor) 21a of, for example, 10 .mu.F
through the circuit "{circle over (4)}.fwdarw.{circle over
(5)}.fwdarw.{circle over (6)}.fwdarw.{circle over
(1)}.fwdarw.{circle over (2)}.fwdarw.{circle over
(3)}.fwdarw.{circle over (7)}.fwdarw.{circle over (4)}".
[0176] On the other hand, when the polarity of the first terminal
MG1 to negative and the polarity of the second terminal MG2 is
positive, first FET 126 is deactivated and third FET 128 is
activated. As a result, the voltage obtained by adding the voltage
induced by generator 20 and the voltage charged to capacitor 123 is
charged to power supply circuit (capacitor) 21a through the circuit
"capacitor 123.fwdarw.{circle over (4)}.fwdarw.{circle over
(7)}.fwdarw.{circle over (6)}.fwdarw.{circle over
(1)}.fwdarw.{circle over (2)}.fwdarw.{circle over
(3)}.fwdarw.capacitor 123" shown in FIG. 15.
[0177] When both ends of generator 20 are short-circuited by a
chopper pulse and generator 20, a high voltage is induced across
both ends of the coil, and power supply circuit (capacitor) 21a is
charged by the high-charging voltage, whereby charging efficiency
is improved.
[0178] When mainspring 1a has a large amount of torque and
generator 20 has a high rotational velocity, an up-counter value
may be input to up/down counter 160 after the counter value is set
to "8". In this case, the counter value is set to "9" and the
brake-activation control of the chopper signal is performed by
chopper signal CH3 to maintain the output QD at the high-level.
Thus, the rotational velocity of generator 20 is lowered by the
application of a brake thereto. When reference signal fs (the
down-count signal) is input twice before rotation sensing signal
FG1 is input, the counter value is lowered from "9" to "8" and then
"7". When the counter value is "7", the control is switched to the
brake-deactivation control for releasing the brake.
[0179] When the above control is carried out, the rotational
velocity of generator 20 approaches a set rotational velocity and
the operation shifts to a lock state in which the up-count signal
(UP) and the down-count signal (DOWN) are alternately input and the
counter value repeats "8" and "7". At that time, the brake is
repeatedly activated and deactivated in accordance with the counter
value. That is, the chopping control is carried out by the
application of the chopper signal having a large duty ratio and the
chopper signal having a small duty ratio to transistors 127, 129 in
one reference cycle during one revolution of the rotor.
[0180] Further, when mainspring 1a is unwound and its torque is
reduced, a brake application time is gradually decreased and the
rotational velocity of generator 20 approaches a reference velocity
even if no brake is applied.
[0181] When many down-count values are input in the absence of the
application of the brake, the count value falls to a value of "6"
or less, which indicates that the torque of mainspring 1a is
diminished. In this event, the user is prompted to rewind
mainspring 1a by the cessation of hand movement or the slow
operation of the hands. Further, a buzzer may be sounded or a lamp
may be lit to alert the user.
[0182] Therefore, when the high-level signal is output from output
terminal QD of up/down counter 160, the brake-activation control is
performed with a chopper signal having a large duty ratio, whereas
when the low-level signal is output therefrom, the
brake-deactivation control is performed with a chopper signal
having a small duty ratio. That is, up/down counter 160 uses
brake-activation control and brake-deactivation control as a brake
controller.
[0183] In the embodiment, when the low-level signal is output from
output terminal QD, chopper signal CH3 is arranged such that
high-level period/low-level period is preferably set to 15:1, that
is, the duty ratio is set to {fraction (1/16)}=0.0625. Whereas,
when the high-level signal is output from output terminal QD,
chopper signal CH3 is arranged such that high-level
period/low-level period is preferably set to 1:15; that is, the
duty ratio is set to {fraction (15/16)}=0.9375.
[0184] As shown in FIG. 18, an a.c. waveform corresponding to the
change of a flux is output from terminals MG1, MG2 of generator 20.
At the time, chopper signals CH3, having a constant frequency and a
different duty ratio are suitably applied to transistors 127, 129
in accordance with the signal from output terminal QD. When output
terminal QD outputs the high-level signal (that is, when the
brake-activation control is performed), the short-circuit brake
time is increased in each chopper cycle to thereby increase the
braking amount so that the rotational velocity of generator 20 is
reduced. Then, although the amount of generated power is reduced
corresponding to the amount of brake applied, the power can be
chopper-boosted by outputting the energy accumulated in the
short-circuit brake when transistors 127, 129 are deactivated by
the chopper signal. Accordingly, the reduction of the generated
power in the short-circuit brake can be compensated so that the
brake torque can be increased while suppressing a drop of the
generated power.
[0185] On the contrary, when the low-level signal is output from
output terminal QD, that is, when the brake-deactivation control is
carried out, the short-circuit brake time is decreased in each
chopper cycle to thereby reduce the braking amount so that the
rotational velocity of generator 20 is increased. Since, even
during this condition, power can be chopper-boosted when
transistors 127, 129 are switched from the deactivated state to the
activated state, the generated power can be improved compared to a
case where control is performed without applying a brake.
[0186] As discussed above, the a.c. output from generator 20 is
boosted and rectified by voltage doubler rectifying circuit 35 and
charged to power supply circuit (capacitor) 21a and rotation
controller 50 is driven by power supply circuit 21a. Since both
output QD of up/down counter 160 and chopper signal CH3 make use of
outputs Q5-Q8 and Q12 of dividing circuit 52 (that is, the
frequency of chopper signal CH3 is made an integral multiple of the
frequency of the output QD), the change in the output level of
output QD (that is, the time at which the brake-activation control
and the brake-deactivation control are switched), and chopper
signal CH3 are synchronized with each other.
[0187] FIG. 20 shows the relationship between the down-count signal
DOWN of 8 Hz, the up-count signal UP of 8 Hz and chopper signal CH3
shown in FIGS. 16-18 in a timing chart. Chopper signal CH3 is
synchronized with the down-count signal DOWN and the up-count
signal UP. However, as shown by chopper signal CH3 of FIG. 20,
chopper signal CH3 need not be synchronized with the down-count
signal DOWN and the up-count signal UP and may have a waveform that
starts from a high-level of the chopper signal CH3' in a certain
cycle of the respective signals DOWN, UP or from a low-level
thereof in a certain cycle thereof. In a preferred embodiment,
however, the brake period is set to a low-level so that a brake is
applied when chopper signal CH3 is at the low-level.
[0188] Further, the chopping signal need not be synchronized with a
velocity set to control the rotation of rotor 12 (that is, with a
velocity that permits the display of the correct time), so long as
rotor 12 is rotated at the correct velocity. More specifically, the
chopping cycle may or may not be synchronized with the set velocity
and the relationship between chopping and the set velocity is not
subject to any restriction.
[0189] This embodiment can provide the following benefits:
[0190] (7) The up-count signal (UP) based on rotation sensing
signal FG1 and the down-count signal (DOWN) based on reference
signal fs are input to up/down counter 160, and where the count
number of rotation sensing signal FG1 (up-count signal) is larger
than the count number of reference signal fs (down-count signal)
(where counter value is at least "8" when the initial value of
up/down counter 160 is set at "7"), a brake is continuously applied
to generator 20 by brake circuit 120, whereas the count number of
rotation sensing signal FG1 is less than the count number of
reference signal fs (where counter value is "7" or less), the brake
of generator 20 is deactivated (off). As a result, even if the
rotational velocity of generator 20 greatly differs from the
reference velocity when generator 20 starts, the rotational
velocity can promptly approach the reference velocity, thereby
improving the responsiveness of rotational control.
[0191] (8) Moreover, since the brake-activation and
brake-deactivation controls are carried out using two types of
chopper signals CH3 having a different duty ratio, brake torque can
be increased without dropping a charged a generated voltage. In
particular, when the brake is applied, since generator 20 is
controlled using the chopper signal having a large duty ratio, the
brake torque can be increased while suppressing a drop of the
charged voltage, whereby the brake control can be effectively
performed, while maintaining the stability of the system. With this
arrangement, the life of the timepiece can also be increased.
[0192] (9) When the brake is not applied, since generator 20 is
chopper controlled by the chopper signal having a small duty ratio,
the charged voltage can be increased when brake is not applied.
[0193] (10) Since the brake-activation control and the
brake-deactivation control is switched depending only upon whether
the counter value is less than or equal to "7" or greater than or
equal to "8", a brake period need not be set, thereby simplifying
the construction of rotation controller 50, and reducing the cost
of parts and manufacturing of the timepiece.
[0194] (11) Since the timing at which the up-count signal (UP) is
input changes in accordance with the rotational velocity of
generator 20, the period during which the counter value is set to
"8" (the period during which the brake is applied) can also be
automatically adjusted. As a result, stable control having prompt
responsiveness is performed in the lock state where the up-count
signal (UP) and the down-count signal (DOWN) are alternately
input.
[0195] (12) Since up/down counter 160 is used as the brake
controller, the count of the respective up-count signals (UP) and
down-count signals (DOWN), and the calculation of the difference
between the respective counted values can automatically be
performed at the same time. As a result, the construction is
simplified, while simplifying the determination of the difference
between the respective counted values.
[0196] (13) Since four-bit up/down counter 160 is used, sixteen
count values can be counted. Therefore, when up-count signals (UP)
are continuously input, the input values can be cumulatively
counted and the accumulated error of the input values can be
corrected within a set range; that is, within a range in which the
up-count signals and the down-count signals are continuously input
and do not reach "15" or "1". As a result, even if the rotational
velocity of generator 20 greatly deviates from the reference
velocity, it can be returned to the reference velocity by reliably
correcting the cumulated error, although it takes time until a lock
state is achieved, whereby the correct operation of the hands can
be maintained in the long run.
[0197] (14) Since the brake control is not carried out until power
supply circuit 21a is charged to a prescribed voltage at the start
of generator 20 by the provision of initializing circuit 190 so
that no brake is applied to generator 20, priority can be given to
the charging of power supply circuit 21a. Thus, rotation controller
50 can promptly and stably be driven by power supply circuit 21a
and the stability of the rotation control executed thereafter also
can be improved.
[0198] (15) Since the time at which the output level from output
terminal QD changes (the time at which the activation- and
deactivation-controls of the brake are switched) is synchronized
with the time at which chopper signal CH3 is changed from an
activated-state to a deactivated-state, a high voltage portion
(shown as the beard-shaped voltage spike in FIG. 21) can be
generated from generator 20 at prescribed intervals in
correspondence to chopper signal CH3 and the output also can be
used as a pace measuring pulse of the clock.
[0199] That is, when output QD is not synchronized with chopper
signal CH3, a high voltage portion is also generated from generator
20 in response to the change of output QD, in addition to chopper
signal CH3 having a prescribed cycle as shown in FIG. 21. As a
result, since the beard portion is not always output at prescribed
intervals in the output waveform of generator 20, it cannot be used
as a pace measuring pulse. However, when output QD is synchronized
with chopper signal CH3 as is the case preferably, the beard
portion also can be used as the pace measuring pulse.
[0200] (16) Since the rectification control of generator 20 is
carried out by first and third FETs 126, 128 whose gates are
connected to terminals MG1, MG2, a comparator need not be used. The
arrangement is therefore simpler and a further drop of the charging
efficiency due to the power consumed by the comparator can be
prevented. Further, field effect transistors 126, 128 are activated
and deactivated making use of the terminal voltages of generator
20, and they can be synchronized with the polarities of the
terminals of generator 20, thereby improving rectifying efficiency.
In addition, since second and fourth field effect transistors 127,
129, which are subjected to the chopping control, are connected in
series to transistors 126, 128, the chopping control can be
independently performed and the arrangement can be simplified.
Therefore, there can be provided a voltage doubler rectifying
circuit 35 that has a simplified arrangement and that can execute
chopper rectification in synchronicity with the polarity of
generator 20 while boosting a voltage.
[0201] Next, a timepiece constructed in accordance with a third
embodiment of the present invention will be described with
reference to FIG. 22, wherein the same numerals as used in the
aforesaid respective embodiments are used to denote components that
are similar or correspond to those of the aforesaid embodiments,
permitting the description thereof to be omitted or simplified.
[0202] The embodiment is arranged such that chopper signal
generator 180' is composed only of second chopper signal generator
185 by omitting first chopper signal generator 181 of the second
embodiment. In this manner, chopper control is carried out by
imposing a chopper signal only in a brake-activation control. That
is, as shown in FIG. 23, since output CH4 from chopper signal
generator 180' is maintained at a high-level in a state where
output terminal QD is set to a low-level signal and a brake is not
applied, transistors 127, 129 are deactivated and the a.c. output
from generator 20 is output. On the other hand, when output
terminal QD is set to a high-level signal and the brake is applied
(in the brake-activation control), output CH4 from chopper signal
generator 180 transmits a chopper signal similar to that of the
first embodiment and chopper control is performed.
[0203] FIG. 24 depicts the relationship between a down-count signal
(DOWN) of 8 Hz, an up-count signal (UP) of 8 Hz and chopper signal
CH4. Although chopper signal CH4 is also synchronized with one
cycle of the down-count signal (DOWN) in this embodiment, chopper
signal CH4 may have the waveform shown as chopper signal CH4' of
FIG. 24. Chopper signal CH4' is not synchronized with the
down-count signal (DOWN), and may start from a high-level of
chopper signal CH4' in a certain cycle of the down-count signal
(DOWN) and a low-level in a certain cycle thereof. In a preferred
embodiment, however, the brake period is set to a low-level so that
the brake is applied when chopper signal CH4 is at the
low-level.
[0204] Further, the chopping signal need not be synchronized with
the velocity set to rotor 12 as was the case in the second
embodiment described above.
[0205] This third embodiment also can achieve benefits similar to
(7), (8), (10)-(16) of the second embodiment, and provide the
following additional advantage:
[0206] (17) Because first chopper signal generator 181 is omitted,
the number of parts can be reduced and cost is reduced.
[0207] Next, a timepiece constructed in accordance with a fourth
embodiment of the present invention will be described with
reference to FIG. 25. In the fourth embodiment, the same numerals
as used in the aforesaid respective embodiments are used to denote
components that are similar or correspond to those of the aforesaid
embodiment, thus permitting the description thereof to be omitted
or simplified.
[0208] The embodiment is arranged such that the frequency of output
CH2 from first chopper signal generator 181 in chopper signal
generator 180" is made different from that of output CH5 from
second chopper signal generator 185 so that two types of chopper
signals having a different frequency can be output as chopper
signal output CH6 from chopper signal generator 180.
[0209] As shown in FIG. 26, in such an embodiment, the frequency of
output CH5 from first chopper signal generator 181' is preferably
set to twice that of output CH2 from second chopper signal
generator 185 by inputting output Q4 from dividing circuit 52 only
to first chopper signal generator 181. Therefore, two types of
chopper signals having different duty ratios and frequencies are
output as output signal CH6 from chopper signal generator 180
depending upon the level of output terminal QD. That is, the
frequency and duty ratio of the chopper signal depend upon whether
a brake activation or a brake deactivation control is performed,
thereby providing the a.c. waveform output from generator 20 shown
in FIG. 27.
[0210] Further, as in the above embodiments, the chopping signal
need not be synchronized with the set velocity of rotor 12 in this
embodiment.
[0211] This fourth embodiment can achieve benefit similar to
(7)-(16) of the second embodiment, and additionally provide the
following benefit:
[0212] (18) A chopper frequency can be produced twice as large as
that of the second embodiment during brake-deactivation control. As
is shown in FIGS. 45 and 46, when a duty ratio is the same, a
higher frequency can reduce drive torque as well as improve a
charged voltage. As a result, in this embodiment, the braking
effect (brake torque) of the brake-deactivation control can be
reduced as compared with the first embodiment, thereby improving
the charged voltage.
[0213] Next, a timepiece constructed in accordance with a fifth
embodiment of the present invention will be described with
reference to FIG. 28. In the fifth embodiment, the same numerals as
used in the aforesaid respective embodiments are used to denote
components that are similar or correspond to those of the aforesaid
embodiment permitting the description thereof to be omitted or
simplified.
[0214] In this embodiment, a chopper signal generator 180'" is
provided that includes a high frequency chopper signal generator
101 for outputting a high frequency chopper signal, a low frequency
chopper signal generator 102 for outputting a low frequency chopper
signal, a power supply voltage sensor 103 for detecting the voltage
of power supply circuit 21a, and a switch 104 for switching an
output CH7 from high frequency chopper signal generator 101 and an
output CH3 from low frequency chopper signal generator 102
depending on the voltage of power supply circuit 21a and outputting
the same.
[0215] The respective chopper signal generators 101, 102 are each
arranged similarly to chopper signal generator 180' of the second
embodiment and include three AND gates 182, 183, 184, two OR gates
186, 187, an AND gate 188, to which the output from OR gate 187 and
output QD from up/down counter 160 are input, and NOR gate 189 to
which the output from AND gate 188 and the output from AND gate 184
are input.
[0216] Since high frequency chopper signal generator 101 makes use
of outputs Q4-Q7 of dividing circuit 52, it can output chopper
signal CH7 having a frequency higher than that of the chopper
signal of low frequency chopper signal generator 102, which makes
use of outputs Q5-Q8 of dividing circuit 52.
[0217] When the voltage charged to power supply circuit (capacitor)
21a is lower than a set value, power supply voltage sensor 103
outputs a low-level signal, whereas when the voltage is higher than
the set value, power supply voltage sensor 103 outputs a high-level
signal.
[0218] Switch 104 includes two AND gates 105, 106 to which the
signal from power supply voltage sensor 103 and the signals from
respective chopper signal generators 101, 102 are input,
respectively, and an OR gate 107 to which the outputs from AND
gates 105, 106 are input.
[0219] When the low-level signal is input from power supply voltage
sensor 103 (when the charged voltage is lower than the
predetermined value), output CH3 from low frequency chopper signal
generator 102 is cancelled by the low-level signal by inverting the
signal input to the AND gate 105 from power supply voltage sensor
103 so that output CH7 from high frequency chopper signal generator
101 is output from OR gate 107 to transistors 127, 129. On the
contrary, when a high-level signal is input from power supply
voltage sensor 103 (when the charged voltage is higher than the
predetermined value), output CH7 from high frequency chopper signal
generator 101 is cancelled by the low-level signal so that output
CH3 from low frequency chopper signal generator 102 is output from
OR gate 107 to transistors 127, 129.
[0220] As a result, when a power supply voltage is low, a chopper
brake control is carried out by the high frequency chopper signal
CH7, whereas when the power supply voltage is high, the chopper
brake control is carried out by the low frequency chopper signal
CH3 as shown in FIG. 29. Since chopper signals CH3 and CH7 have the
same duty ratio, respectively when a brake-activation control and a
brake-deactivation control are carried out, high frequency chopper
signal CH7 has a lower drive torque and a higher charged voltage
(i.e., priority is given to charging), whereas low frequency
chopper signal CH3 has higher drive torque and a lower charged
voltage and thus performs chopper control giving priority to
braking.
[0221] As with earlier embodiments, the chopping signal need not be
synchronized with the velocity of rotor 12 in this embodiment.
[0222] This embodiment can achieve advantages similar to (7)-(16)
of the second embodiment, and offers the following additional
advantage:
[0223] (19) Because high frequency chopper signal generator 101,
low frequency chopper signal generator 102, power supply voltage
sensor 103 and switch 104 are provided as chopper signal generator
180'", and the frequency of the chopper signal changes depending on
the power supply voltage value, chopper control can be performed
that corresponds to the charged state of generator 20, thereby
performing a more effective brake control.
[0224] The present invention is not limited to the above
embodiments as modifications and improvements that fall within a
range in which the object of the present invention can be achieved
are included in the present invention. Again, for the following
embodiments like numbers indicate like parts.
[0225] As reference is now made to FIG. 30 in which another
embodiment of the invention is provided. Rotation controller 50 may
include a F/V (frequency/velocity) converter 100 that converts the
output frequency of waveform shaping circuit 70 into velocity
information. Since the rotational velocity information of generator
20 can be obtained by the provision of F/V converter 100, the
rotational velocity of generator 20 can be controlled so that it
approaches a predetermined velocity, that is, a time standard
signal. As a result, even if a waveform of generated power greatly
varies instantly and deviates from a lock range, the control of
generator 20 can be maintained, and a more stable system can be
constructed.
[0226] Chopper charging circuit 60 is not limited to that disclosed
in the above embodiments. For example, as shown in FIG. 31, a
chopper charging circuit 110 constructed in accordance with another
embodiment of the invention composed of a comparator 111 is coupled
across coils 15b, 16b for detecting the polarity of rotor 12.
Furthermore, diodes 112 are coupled between a respective coil end
and a respective one of chopping transistors 66, 67. Diodes 112'
are coupled between resistors 113 and a clock CLK signal.
[0227] Since comparators 61, 62 are used to detect polarity in the
above embodiments, power supply 63 is needed to supply a
comparative reference voltage Vref to comparators 61, 62. The
embodiment of FIG. 31, however, makes power supply unnecessary. In
chopper charging circuit 110, depending upon the polarity of a
power generating coil, transistors 66, 67 are driven by the coil
terminal voltage through diodes 112 to make transistors 66, 67
conductive. For this purpose, the coil terminal voltage must be
made higher than a voltage which is obtained by adding a threshold
voltage Vth capable of driving transistors 66, 67 to the rising-up
voltage Vf of diodes 112. When, for example, Vth=0.5 V and diode
Vf=0.3, 0.8 V is needed to satisfy the above requirement, and
generator 20 must have a generating capability of about 1.0-1.6 V.
As a result, chopper charging circuit 60 of the above embodiments
in which transistors 66, 67 are driven without the diodes is
preferable in that a chopper charging operation can be more
effectively carried out by a small voltage generated by generator
20.
[0228] Further, the chopper charging circuit may be arranged such
that transistors 66, 67 of chopper charging circuit 60 shown in
FIG. 6 are changed to a P-channel type, further transistors 66, 67
can be replaced with diodes 68, 69 to thereby short-circuit them to
the positive side (VDD) of capacitor 21a (first power supply line)
so that the voltage of capacitor 21a is boosted to a voltage less
than the voltage of the VTKN when transistors 66, 67 are released.
In this case, the outputs from comparators 61, 62 are ANDed with
the output of clock signal CLK by an AND circuit and input to the
gates of transistors 66, 67.
[0229] Likewise, in the second to fifth embodiments, the first and
second switches 121, 122 may be replaced with a capacitor 123 and a
diode 124 and disposed to the negative side (VSS) of capacitor 21a
(second power supply side). That is, transistors 126-129 of
respective switches 121, 122 are changed to N-channel type and
inserted between terminals MG1, MG2 of generator 20 and the
negative side (VSS) of capacitor 21a as the power supply on the low
voltage side (second power supply line side). In this case, the
circuit is arranged to permit switches 121, 122 connected to the
negative terminal of generator 20 to be continuously activated and
switches 121, 122 connected to the positive terminal thereof to be
intermittently activated.
[0230] Further, a chopper charging circuit that simultaneously
activates and deactivates transistors 66, 67 may be used in the
first embodiment.
[0231] In addition, chopper charging circuits 200, 300, 400, 500,
600 as shown in FIGS. 32-36 may be used, respectively, in the first
embodiment. In chopper charging circuits 200-600, components that
are similar or correspond to those of the above embodiments are
denoted by the same numerals and the description thereof is
omitted.
[0232] Chopper charging circuit 200 shown in FIG. 32 is arranged
such that a capacitor 201 is connected in series to the coil of
generator 20, and a capacitor 21a and an IC 202 are connected in
parallel to generator 20. A chopping switch 203 for executing
chopping under the control of IC 202 is connected in parallel to
generator 20. A parasitic diode 204 is connected in parallel to
switch 203.
[0233] In this manner, a benefit similar to the benefit denoted as
(2) of the first embodiment is achieved. Brake torque can be
improved without dropping a charged voltage in chopper charging
circuit 200 because energy is charged to capacitor 201 when a
short-circuit brake is applied to generator 20 by turning
activating switch 203. Further, power in which a generated voltage
is increased by containing the energy of capacitor 201 can be
charged to capacitor 21a when switch 203 is deactivated. In
addition, because parasitic diode 204 also acts as the diode of a
boosting/rectifying circuit, the number of parts can be reduced
thus achieving a part and manufacture cost reduction.
[0234] Chopper charging circuit 300, shown in FIG. 33, differs from
chopper charging circuit 200 in that rectifying diodes 301, 302 are
added to chopper charging circuit 200.
[0235] Chopper charging circuit 300 is more expensive than chopper
charging circuit 200 because it includes an additional diode 301 in
parallel with generator 20 and capacitor 201 and a second diode 302
between generator 20 and switch 203. However, chopper charging
circuit 200 has a drawback because when switch 203 is connected and
short-circuited, the charge of capacitor 201 flows to switch 203,
thereby reducing a generated voltage improving ratio when a
short-circuit time is increased. Whereas, the advantage of chopper
charging circuit 300 is that since it can prevent the charge of
capacitor 201 from flowing to switch 203 when switch 203 is
connected, it can increase boosting performance as compared with
chopper charging circuit 200.
[0236] Chopper charging circuit 400 shown in FIG. 34 is similar to
chopper charging circuit 300, the primary difference being an
additional switch 203b and diodes 204b, 302b used in chopper
charging circuit 300 to execute chopping to both the positive and
negative waves of the a.c. output of generator 20. Like numbers are
utilized to indicate like structure.
[0237] A second switch 203b is coupled across generator 20 parallel
with a diode 204b. A diode 302b is coupled in series with switch
203b and generator 20. A first switch 203a with diodes 204a and
302a are coupled in mirror image and in parallel with the circuit
of switch 203b. As a result, boosting and braking control can be
performed over the entire cycle of the a.c. output of generator 20,
thereby increasing boosting performance and braking
performance.
[0238] Chopper charging circuit 500 shown in FIG. 35 is a voltage
doubler rectifying circuit capable of imposing a voltage twice as
large as the voltage generated by generator 20 on IC 202 by the
provision of two capacitors 501, 502. Diodes 510 are coupled in
series across IC 202. A generator is coupled between the junction
of diodes 510 at its one end and capacitors 501, 502 at its other
end. Capacitors 501, 502 are coupled in parallel with a first diode
302a and is coupled in series with a switch 203a, which is coupled
in parallel with generator 20. A second diode 302b is coupled in
series with a switch 203b, which in turn is coupled in parallel
with generator 20.
[0239] Chopper charging circuit 600 shown in FIG. 36 achieves
chopping by a full wave rectifying circuit having rectifying diodes
601. A capacitor 201 is coupled across diodes 601. Diodes 601 are
also in parallel with generator 20 and a series connection of diode
302a in series with switch 203a and diode 302b in series with a
switch 203b.
[0240] Although chopper charging circuit 500, 600 are arranged to
carry out chopping to a full wave, they may be arranged to carry
out chopping to a half wave. Chopper charging circuits 300-600 can
also obtain an advantage similar to that numbered (2) of the first
embodiment.
[0241] Further, the arrangement of rotation sensing circuit 53, LPF
55 and brake control circuit 56 is not limited to the arrangement
composed of waveform shaping circuit 70, charge pump 80, loop
filter 81, signal output circuit 90, dividing circuit 91 and
triangular wave generating circuit 92 as shown in the first
embodiment. For example, latch 76, as shown in FIG. 37, may be used
as the waveform shaping circuit 70. Although one embodiment of
waveform shaping circuit 70 shapes the rectangular wave pulse fr
only by the output from one of comparators 61, 62 as shown in FIG.
6, waveform shaping circuit 70 shown in FIG. 37 applies latch 76 in
response to the ascending edge of the output for detecting the
polarity of terminal AG1 (comparator 62) and is reset in response
to the output from comparator 61 of terminal AG2 as shown in FIG.
9. This arrangement has an advantage that time is not delayed and
detection can be accurately performed, although two outputs must be
used. When latch 76 is applied in response to the output of
terminal AG1, even if the output at terminal AG1 causes a lack of
pulse, it is ignored. Accordingly, an affect to the rectangular
wave pulse fr can be prevented.
[0242] The rotation controller is not limited to that using the PLL
control as shown in the first embodiment and the one using up/down
counter 160 as shown in the second through fifth embodiments. The
rotation controller may control a rotational velocity only by the
output from, for example, F/V converter 100. Further, generator 20
is not limited to a two-pole rotor, but may be a generator using a
multi-pole rotor.
[0243] Although the second to fifth embodiments use a four-bit
up/down counter 160 as the brake controller, an up/down counter of
three bits or less and an up/down counter of five bits or more may
be used. Since the use of an up/down counter having a larger number
of bits increases a countable value, the range in which a cumulated
error can be stored is increased, which is particularly
advantageous in the control executed in a non-lock state just after
the start of generator 20, for example. On the other hand, the use
of a counter having a small number of bits has the advantage that a
one-bit counter can handle the operation at a reduced cost,
although the range in which an accumulated error can be stored is
reduced, because an up-count and a down-count are repeated
particularly in a lock state.
[0244] The brake controller is not limited to an up/down counter
and may include first and second counters for use with reference
signal fs and rotation sensing signal FG1, respectively, and a
comparison circuit for comparing the values counted by the
respective count means. However, the use of up/down counter 160 is
advantageous in that it simplifies a circuit arrangement. Further,
any arrangement may be employed as the brake controller so long as
it can detect the rotational cycle of generator 20 and activate the
brake-activation control and the brake-deactivation control based
on the rotational cycle of generator 20.
[0245] Although the brake control can be carried out using two
types of chopper signals having different duty ratios and different
frequencies in the above embodiments, three or more types chopper
signals having different duty ratios and different frequencies may
be used.
[0246] The specific arrangements of voltage doubler rectifying
circuit 35, brake circuit 120, brake control circuit 56, chopper
signal generator 180 and the like are not limited to those of the
above respective embodiments and any arrangements may be used so
long as they can chopper control generator 20 of an electronically
controlled mechanical timepiece.
[0247] For example, as is shown in the embodiment of FIG. 38, a
diode 125a may be provided in place of capacitor 123 as chopper
rectifying circuit 35 of brake circuit 120. Again, like numbers are
utilized to indicate like structure. In this case, since a boosting
circuit is not formed, chopper rectifying circuit 35 functions as a
simplified synchronized chopper rectifying circuit. That is, when
the polarity of the first terminal MG1 is positive and that of the
second terminal MG2 is negative, first field effect transistor
(FET) 126 is activated and third field effect transistor (FET) 128
is deactivated. As a result, the voltage charge generated by
generator 20 is charged to power supply circuit (capacitor) 21a
through the circuit "{circle over (4)}.fwdarw.{circle over
(5)}.fwdarw.{circle over (6)}.fwdarw.{circle over
(1)}.fwdarw.{circle over (2)}.fwdarw.{circle over
(3)}.fwdarw.{circle over (7)}.fwdarw.{circle over (4)}" as is shown
in FIG. 38. On the other hand, when the polarity of the first
terminal MG1 is negative and the polarity of the second terminal
MG2 is positive, first FET 126 is deactivated and third FET 128 is
activated. As a result, the voltage charge generated by generator
20 is charged to power supply circuit (capacitor) 21a through the
circuit "{circle over (7)}.fwdarw.{circle over (6)}.fwdarw.{circle
over (1)}.fwdarw.{circle over (2)}.fwdarw.{circle over
(3)}.fwdarw.{circle over (4)}.fwdarw.{circle over (7)}" as is shown
in FIG. 38.
[0248] The frequency of the chopper signal in the above embodiments
may be set at an appropriate level depending on the system
components and circuit construction. However, when the cycle is,
for example, 50 Hz or more (about five times as large as the
rotational frequency of the rotor of generator 20), brake
performance can be improved while keeping a charged voltage to a
prescribed value or more. Further, the duty ratio of the chopper
signal may be appropriately set according to the components of a
specific arrangement.
[0249] The rotational frequency (reference signal) of the rotor is
not limited to 10 Hz of the first embodiment and the 8 Hz of second
embodiment and may be appropriately chosen in accordance with the
specific components.
[0250] A rotor rotation sensing circuit 800 as shown in FIG. 39 may
be used to detect the rotation of the rotor as rotation sensing
circuit 53. That is, when generator 20 is controlled by chopping, a
chopper pulse is superimposed on the rotational waveform of rotor
12 of generator 20. The voltage of the rotational waveform of rotor
12 is compared with the reference voltage at the time the chopper
waveform is superimposed to obtain a rectangular wave signal (rotor
rotation sensing signal MGOUT) that corresponds to a rotor
rotational cycle from the rotational waveform of rotor 12. At the
time, noise such as an external magnetic field (for example, a
commercial power supply having a frequency of {fraction (50/60)}
Hz) may be superimposed on the rotational waveform of rotor 12 and
there may arise such a case that the rotational waveform of rotor
12 is deformed by being affected by the noise and a rotor rotation
signal cannot be obtained.
[0251] To cope with the noise problem, rotor rotation sensing
circuit 800 includes a rotor pulse sensing circuit 801 coupled to
the coil of generator 20 and the chopper signal for detecting
whether the voltage of a rotor pulse VMG2 exceeds a reference or
threshold voltage VROTD at the time of chopping. Rotor Pulse
sensing circuit 80 provides an output to a first counter 802 for
counting the number of consecutive times rotor voltage VMG2 exceeds
a reference voltage and registering a first count. Counter 802
inputs the first count to a comparator 803 for comparing the first
count of first counter 802 with a predetermined value p (which, for
example, may be set to three) and detecting whether the first count
is greater than predetermined value p. Rotor pulse sensing circuit
801 also provides an input to a second counter 804 for counting the
number of times rotor voltage VMG2 is in excess of reference
voltage VROTD and is not continuously detected by rotor pulse
sensing circuit 801 and registering a second count. Counter 802
outputs the second count to a comparator 805 for comparing the
second count of second counter 804 with a second predetermined
value r (which, for example, may be set to three) and detecting
whether the second count is greater than second predetermined value
r. A pulse generator 806 outputs rotor rotation sensing signal
MGOUT based on the results of comparisons executed by comparators
803, 805.
[0252] Referring to FIG. 40, a preferred embodiment is displayed
where reference voltage VROTD is set to 0.5 V and each pulse is
depicted as a broken horizontal line. When voltage VMG2 of
generator 20 exceeds reference voltage VROTD for a predetermined
value p pulses (set, preferably, to three consecutive pulses),
rotation sensing signal MGOUT drops from a high-level signal to a
low-level signal, and a brake is applied to generator 20 by chopper
control (BRAKE shown as a low-level signal). Whereas when voltage
VMG2 of generator 20 does not exceed reference voltage VROTD for a
predetermined value r pulses (set, preferably, to three consecutive
pulses), rotation sensing signal MGOUT switches to a high-level
signal, and the brake is released (depicted as BRAKE shown as a
high-level signal). As such, since MGOUT switches from a high-level
signal to a low-level signal once during each rotation of rotor 12,
the rotation of rotor 12 can be reliably detected as shown in FIG.
40. MGOUT is compared with a reference signal (for example, 8 Hz)
and a brake is applied during the time that the reference signal
exceeds MGOUT to thereby regulate the velocity of rotor 12.
[0253] Although the values p and r may differ depending on the
components used, they may be based on the noise frequency
superimposed on the rotational cycle of rotor 12. For example,
referring to FIG. 41, when 50 Hz noise (1 Vp-p sine wave) is
superimposed on a 8-Hz rotational waveform (2 Vp-p sine wave) of
rotor 12 and the chopping frequency is 256 Hz, about five cycles of
the chopping frequency occurs during one cycle of the 50 Hz noise.
Therefore, even if noise is superimposed on the rotational waveform
of rotor 12, whether the rotational waveform exceeds the reference
voltage can be determined depending upon whether one-half or more
of the rotational waveform (the amount of three cycles of the
continuous chopping frequency) exceeds the reference voltage. As
such, the values p and r are preferably set to three times.
[0254] As is shown in FIGS. 42 and 43, a rotor rotation sensing
circuit 800' constructed similarly to rotation sensing circuit 800,
may include in place of counter 804, a counter 804' for counting
the number of times voltage VMG2 does not exceed reference voltage
VROTD, regardless of whether the non-detection occurs
consecutively. In this case, a value v may be set, for example, to
a value of two. Thus, where the number of consecutive pulses in
which detected voltage VMG2 exceeds reference voltage VROTD is two,
rotation sensing signal MGOUT drops from a high-level signal to a
low-level signal. A value w may be set, for example, to a value of
five. In this way, when the voltage VMG2 does not exceed reference
voltage VROTD and is not detected, even if voltage VMG2 does not do
so consecutively, rotation sensing signal MGOUT switches to a
high-level signal. Thus, non-detection may be set based on the
chopping frequency and the noise frequency to be superimposed on
the rotational frequency of rotor 12. The detection of the rotation
of rotor 12 where noise is superimposed on the rotational waveform
of rotor 12 permits the rotation of rotor 12 to be correctly
detected even if a clock is used in an environment where noise is
likely to occur.
[0255] The use of chopper rectifying circuit 35 shown in FIG. 15
and FIG. 38 is not limited to the electronically controlled
mechanical timepiece of the above embodiments. It is applicable to
timepieces, such as wrist watches, table clocks, other types of
clocks, portable sphygmomanometers, portable phones, pagers,
pedometers, pocket calculators, portable personal computers,
electronic notebooks, portable radios and the like. In short, it
can be widely used in any type of electronic equipment that
consumes electrical power. If, incorporated in an electronic
circuit, such a chopper circuit can drive a mechanical system by a
generator without a battery, thereby rendering a battery and the
need to replace the battery unnecessary.
[0256] Further, it is possible to use the present invention in
combination with other power-generating mechanisms by which battery
replacement is made unnecessary, for example, a self-winding power
generating mechanism and a self-power-generating device such as a
solar cell, a thermo-power-generating device and the like.
[0257] The effect of the present invention is described next in
connection with an example.
[0258] A chopper charging circuit 700, shown in FIG. 44, was used
in the following experiment. Chopper charging circuit 700 was
constructed similarly to chopper charging circuit 300 shown in FIG.
33 and arranged such that a capacitor 201 of 0.1 .mu.F was
connected in series to the coil of generator 20. A capacitor 21a of
1 .mu.F and chopping switch 203 were connected in parallel with
generator 20. Further, a resistor 205 of 10 M.OMEGA. was disposed
in place of an IC as well as rectifying diodes 301, 302 were
provided.
[0259] The voltages charged to capacitor 21a (generated voltages)
and drive torque were measured at the respective values of a duty
cycle which represents the activation ratio of switch 203 when the
chopping frequency of switch 203 was switched to five stages of
frequencies; that is, to 25, 50, 100, 500, 1000 Hz. FIGS. 45 and 46
show the results of the experiment. The rotational frequency of the
rotor of generator 20 was set to 10 Hz. Since an electronically
controlled mechanical timepiece had IC 202, which was ordinarily
set to be driven by 0.8 V and 80 nA, when 0.8 V was charged to
capacitor 21a in circuit 700, a current of 80 nA flowed to resistor
205 of 10 M.OMEGA. so that a voltage sufficient to drive IC 202 was
charged.
[0260] As is apparent from the results of the experiment shown in
FIG. 45, a voltage exceeding 0.8 V was charged except where the
chopping frequency was 25 Hz. Thus, charged voltage could be
maintained using chopper charging circuit 700 to a prescribed value
of 0.8 V or more.
[0261] FIG. 46 shows the results of the measurement of the torque
for driving generator 20 under the chopping conditions shown in
FIG. 45. Drive torque is necessary to rotate generator 20 at 10 Hz
and similar to the torque by which generator 20 applies a brake to
mainspring 1a. As is shown in FIG. 46, when the duty reaches 0.9,
nearly the same drive torque can be obtained independent of the
chopper frequency, although the drive torque curves are different
depending upon the chopping frequencies as the duty is
increased.
[0262] Therefore, when the chopper frequency is 50 Hz, that is, at
least five times as large as the rotational frequency of the rotor,
brake performance can be improved while maintaining the charged
voltage to at least the prescribed value, thus confirming the
effectiveness of the present invention.
[0263] As is shown in FIG. 45, even if chopper frequency is 25 Hz,
at least 0.8 V can be charged when the duty is 0.80 or less.
Accordingly, the chopping frequency of 25 Hz also can be also used
by suitably setting the duty value.
[0264] Although the chopper frequency was measured only up to 1000
Hz in the experiment, it is presumed that the sane effect can be
achieved by a larger chopper frequency. However, when the chopper
frequency is excessively large, the IC for chopping consumes a
large amount of power, and therefore power to be generated by the
generator is increased. Thus, preferably, the upper limit of the
chopping frequency is set to above 1000 Hz; that is, to about
one-hundred times as large as the rotational frequency of the
rotor. In the event that an IC can be constructed that consumes
less power, the upper limit of the dropping frequency will increase
accordingly.
[0265] The characteristics shown in FIGS. 45 and 46 are not limited
to the case where the rotational frequency (reference signal) of
rotor 12 of generator 20 is 10 Hz. A similar tendency is also
established at other frequencies. Accordingly, the rotational
frequency may be appropriately set depending on the timepiece
construction, and the same effect can be achieved with any
rotational frequency.
[0266] It will thus be seen that the objects set forth above, among
those made apparent from the preceding description are efficiently
obtained and, since certain changes may be made in carrying out the
above method and in the constructions set forth without departing
from the spirit and scope of the invention, it is intended that all
matter contained in the above description and shown in the
accompanying drawings shall be interpreted as illustrative and not
in a limiting sense.
[0267] It is also to be understood that the following claims are
intended to cover all of the generic and specific features of the
invention herein described and all statements of the scope of the
invention which, as a matter of language, might be said to fall
therebetween.
* * * * *