Power supply for electronic timpiece

• US 4,730,287 A
• Filed: 04/09/1986
• Issued: 03/08/1988
• Est. Priority Date: 04/10/1985
• Status: Expired due to Term

• Current Assignee: Seiko Epson Corporation (Seiko Group)
• Original Assignee: Seiko Epson Corporation (Seiko Group)
• Inventors: Nishiwaki, Yoshitsugu, Yoshino, Masahito
• Primary Examiner(s): Roskoski, Bernard
• Application Number:
  US06/849,932
• Time in Patent Office: 699 Days
• Field of Search: 368/205, 323/906, 320/1, 320/2, 363/59, 363/60, 307/110
• US Class Current: 368/205
• CPC Class Codes: G04C 10/02 the power supply being a radioactive or photovoltaic source
• CPC Class Codes: G04G 19/02 Conversion or regulation of current or voltage

Abstract

To increase the utilization by an electric timepiece, such as a quartz watch, of the electric energy derived from a primary source, such as a photo cell, which energy is stored in a multi-layer capacitor, the voltage on the capacitor is fed to transfer capacitors which are connected in series or in parallel to be charged from the multi-layer capacitor and then connected in series or in parallel to charge an auxiliary capacitor which drives the movement of the timepiece. Provisions are made for starting the watch when the stored voltage is less than the operating voltage of the watch movement.

Claims

1. An electronic timepiece comprising:

a primary source of electric power;

a secondary power source which is charged by the primary source and whih has an output voltage which changes with use of power stored therein;

a timepiece movement; and

a supply circuit which delivers power from the secondary power source to the timepiece movement, the supply circuit comprising;

detector means responsive to the level of the output voltage of the secondary power source to provide a control signal when the output voltage has fallen to a predetermined voltage level;

booster means in the supply circuit, the booster means being responsive to the control signal for transforming voltage from the secondary power source to a higher level for delivery to the timepiece movement;

an auxiliary power source which is charged by the booster means above the predetermined voltage level and which delivers the charge to the timepiece movement; and

whereby the level of voltage supplied to the timepiece movement from the secondary power source is maintained above the predetermined level.

2. An electronic timepiece in accordance with claim 1 in which the auxiliary storage means comprises an auxiliary storage capacitor.

3. An electronic timepiece in accordance with claim 1, wherein the means for transforming voltage to a different level further comprises:

at least one transfer capacitor; and

switch means responsive to the control signal for first coupling the transfer capacitor in parallel with the secondary power source to be charged and then in series with the secondary power source to deliver energy to the auxiliary storage means, whereby the charge delivered from the secondary power source to the auxiliary storage means is boosted by the charge stored in the transfer capacitor and the voltage level of the auxiliary storage means is raised above the level of the secondary power source.

4. An electronic timepiece in accordance with claim 1, wherein the means for transforming voltage to a different level further comprises:

at least two transfer capacitors; and

switch means responsive to the control signal to first couple the transfer capacitors in series with each other to be charged from the secondary power source and then to couple the capacitors in parallel with each other and in series with the secondary power source to charge the auxiliary storage means.

5. An electronic timepiece in accordance with claim 1, wherein the means for transforming voltage to a different level further comprises:

at least two transfer capacitors; and

switch means responsive to the control signal to first couple the transfer capacitors in parallel with each other and with the secondary power source to be charged and then to couple the transfer capacitors in parallel with each other and in series with the secondary power source to charge the auxiliary storage means.

6. An electronic timepiece in accordance with claim 1, wherein the means for transforming the voltage to a different level further comprises:

at least two transfer capacitors; and

switch means responsive to the control signal to first couple the transfer capacitors in parallel with each other to be charged from the secondary power source and then to couple the transfer capacitors in series with each other and with the secondary power source to charge the auxiliary storage means.

7. An electronic timepiece in accordance with claim 1, wherein the detector means provides at least first and second control signals in response to the detection of first and second predetermined voltage levels in the supply circuit, and wherein the means for transforming voltage to a different level further comprises:

at least two transfer capacitors; and

switch means responsive to the first control signal to first couple the transfer capacitors in series with each other to be charged from the secondary power source and then to couple the transfer capacitors in parallel with each other and in series with the secondary storage means to charge the auxiliary storage means, and the switch means responsive to the second control signal to first couple the transfer capacitors in parallel with each other to be charged from the secondary power source and to then couple the transfer capacitors in parallel with each other and in series with the secondary power source to charge the auxiliary storage means.

8. An electronic timepiece in accordance with claim 7, wherein the detector means provides a third control signal in response to detection of a third predetermined voltage level in the supply circuit, and wherein the switch means responds to the third control signal to first couple the transfer capacitors in parallel with each other and with the secondary power source to be charged and then to couple the transfer capacitors in series with each other and with the secondary power source to charge the auxiliary storage means.

9. An electronic timepiece in accordance with claim 1, wherein the detector means provides first and second control signals in response to detection of predetermined first and second voltage levels, respectively, in the supply circuit and wherein the means for transforming voltage to a different level further comprises:

at least two storage capacitors; and

switch means responsive to the first control signal to first couple the transfer capacitors in parallel with each other to be charged from the secondary power source and then to couple the transfer capacitors in parallel with each other and with the secondary power source to charge the auxiliary storage means, and the switch means responsive to the second control signal to first couple the transfer capacitors in parallel with each other and with the secondary power source to be charged and then to couple the transfer capacitors in series with each other and with the secondary power source to charge the auxiliary storage means.

10. An electronic timepiece in accordance with claim 3, wherein the switch means comprises a plurality of switching transistors.

11. An electronic timepiece in accordance with claim 1, wherein the detector means further comprises:

means having a reference voltage level as an output; and

means for comparing the voltage level at the predetermined point in the supply circuit with the reference voltage level to provide the control signal when the predetermined voltage level is present.

12. An electronic timepiece in accordance with claim 11, and further comprising:

logic means responsive to the comparison signal for controlling the transforming means.

13. An electronic timepiece in accordance with claim 7, wherein the detector means further comprises:

means having at least first and second reference voltage levels as outputs; and

means for comparing the voltage level at the predetermined point in the supply circuit with the first and second reference voltage levels to provide one of the first and the second control signals for initiating a respective voltage transformation when one of the first and the second predetermined voltage level is present.

14. An electronic timepiece in accordance with claim 13, wherein a third reference voltage level is provided for comparison with the voltage level at the predetermined point to provide a third control signal for initiating a third voltage transformation when a voltage having a third predetermined level is present.

15. An electronic timepiece in accordance with claim 3, and further comprising:

control means coupled to the detector means for cyclically actuating the detector to determine the voltage level at the predetermined point in the supply circuit, whereby the voltage level of the auxiliary storage means is repeatedly boosted.

16. An electronic timepiece in accordance with claim 1, wherein the watch movement further comprises an oscillator which is powered by the supply circuit, and further comprising:

detector means coupled to the output of the oscillator for providing a failure signal in the event that oscillation stops; and

switch means responsive to the failure signal to disconnect the oscillator from the supply circuit and to connect it to the secondary power source to reestablish oscillation.

17. The electronic timepiece of claim 16, wherein when oscillation is reestablished, the switch means reconnects the oscillator to the supply circuit.

18. An electronic timepiece in accordance with claim 1, wherein the secondary power source is a storage capacitor.

19. The electronic timepiece of claim 1 and further comprising:

coupling means for coupling the primary source to the secondary power source and for providing, when the primary source begins operating and when insufficient energy is stored in the secondary power source to provide the minimum operating voltage to the timepiece movement, a voltage from the primary source for supply to the timepiece movement which rises quickly above the minimum operating voltage prior to the time that the voltage on the secondary power source rises to the minimum operating level.

20. The electronic timepiece of claim 19, wherein the coupling means limits current flow to the secondary power source until the voltage level of the secondary power source reaches at least the minimum operating voltage.

21. The electronic timepiece of claim 20, wherein the coupling means includes switch means responsive to a control signal for connecting the secondary power source directly to the primary source when the voltage level of the secondary power source is at least at the minimum operating voltage.

22. The electronic timepiece of claim 21 wherein the coupling means comprises a resistor and the switch means comprises a transistor connected in parallel with the resistor.

23. The electric timepiece of claim 21:

wherein the auxiliary storage means is of lesser capacity than the secondary power source.

24. The electronic timepiece of claim 23 wherein the primary source comprises a solar battery, the secondary power source comprises a double-layer capacitor, and the auxiliary storage means comprises a tantalum electrolytic capacitor.

25. The electronic timepiece of claim 23 and further comprising:

detector means for generating the control signal when the voltage on the secondary power source has reached a predetermined level.

26. The electronic timepiece of claim 23 and further comprises:

means coupled to the timepiece movement for providing the control signal when the timepiece movement is operative.

27. The electronic timepiece of claim 19 wherein the primary source comprises a solary battery.

28. The electronic timepiece of claim 1, wherein when the detector means detects the voltage level of the secondary power source falling below a second predetermined level, the booster means maintains the voltage level supplied to the timepiece above the first predetermined level and when the detector means detects the voltage level of the secondary power source falling below a third predetermined voltage level the booster means maintains the voltage level supplied to the timepiece above the first predetermined level, wherein the first predetermined voltage level is greater than the second predetermined voltage level and the second predetermined voltage level is greater than the third predetermined voltage level.

29. The electronic timepiece of claim 9, wherein when the detector means detects the voltage level of the secondary power source falling below a second predetermined level the booster means maintains the voltage level supplied to the timepiece above the first predetermined level and when the detector means detects the voltage level of the secondary power source falling below a third predetermined voltage level the booster means maintains the voltage level supplied to the timepiece above the first predetermined level, wherein the first predetermined voltage level is greater than the second predetermined voltage level and the second predetermined voltage level is greater than the third predetermined voltage level.

30. An electronic timepiece comprising:

means for converting externally supplied energy into electricity;

timekeeping means having a minimum operating voltage;

first storage means for coupling the converting means to the timekeeping means, the first storage means receiving and storing electricity from the converting means and delivering stored electricity to operate the timekeeping means;

auxiliary storage means, having a capacity less than the capacity of the first storage means, said auxiliary storage means being charged by the converting means and the first storage means and delivering power to the timekeeping means;

a reverse current prevent element coupled between the auxiliary storage means and the first storage means;

a high impedance element coupled between the converting means and the first storage means; and

coupling means for coupling the converting means to the auxiliary storage means when the voltage being supplied to the timekeeping means by the first storage means is below the minimum operating voltage, so that, when the voltage level of the first storage means is less than the minimum operating voltage, a greater amount of current supplied by the converting means flows to the auxiliary storage means than to the first storage means.

31. The electronic timepiece of claim 30 wherein the coupling means limits current flow to the storage means until the voltage level of the storage means reaches at least the minimum operating voltage.

32. The electronic timepiece of claim 31, wherein the coupling means includes switch means responsive to a control signal for connecting the storage means directly to the converter means when the voltage level of the storage means is at least the minimum operating voltage.

33. The electronic timepiece of claim 32 wherein the coupling means comprises a resistor and the switch means comprises a transistor connected in parallel with the resistor.

34. The electronic timepiece of claim 32 wherein the converting means comprises a solar battery, the storage means comprises a double-layer capacitor, and the auxiliary storage means comprises a tantalum electrolytic capacitor.

35. The electronic timepiece of claim 32 and further comprising:

detector means for generating the control signal when the voltage on the storage means has reached a predetermined level.

36. The electronic timepiece of claim 32 and further comprising:

means coupled to the timekeeping circuit for providing the control signal when the timekeeping means is operative.

37. The electronic timepiece of claim 32 and further comprising:

means coupled between the storage means and the auxiliary storage means and responsive to a control signal for transforming voltage from the storage means to a different level for delivery by the auxiliary storage means to the timekeeping means.

38. The electronic timepiece of claim 30 wherein the converting means comprises a solar battery.