Voltage conversion system for electronic timepiece

• US 4,259,715 A
• Filed: 06/05/1978
• Issued: 03/31/1981
• Est. Priority Date: 09/27/1975
• Status: Expired due to Term

• Current Assignee: Citizen Watch Co Limited (Citizen Electronics Company Limited)
• Original Assignee: Citizen Watch Co Limited (Citizen Electronics Company Limited)
• Inventors: Morokawa, Shigeru
• Primary Examiner(s): Shoop, William M.
• Application Number:
  US05/912,267
• Time in Patent Office: 1,030 Days
• Field of Search: 58/23 A, 58/23 BA, 363/60, 363/61, 363/62, 363/63
• US Class Current: 363/60
• CPC Class Codes: G04G 19/04 Capacitive voltage division or multiplication
• CPC Class Codes: H02M 3/07 using capacitors charged and discharged alternately by semiconductor devices with control electrode , e.g. charge pumps

Abstract

A voltage conversion system for an electronic timepiece having a power source as a lithium battery, which system generates power at lower voltage level than that of the power source for operating at least one of a frequency standard, a frequency converter, a time counter circuit and a display system. The voltage conversion system comprises an oscillator circuit coupled to the power source to generate output signals, a plurality of capacitors, and a plurality of switching elements responsive to the output signals for alternately setting the capacitors in a parallel connected condition and a series connected condition, whereby an output voltage lower than that of the power source is generated at an output terminal of the system.

Claims

1. A voltage convertion system coupled to a power source having high and low potentials, to provide a lower output voltage than that of the power source, comprising:

a plurality of capacitors; and

a plurality of different types of fieled effect transistors for switching connections of said plurality of capacitors relative to the power source for thereby providing said lower output voltage, one type of said plurality of field effect transistors having a source electrode connected to the high potential of said power source, and another type of said plurality of field effect transistors having a source electrode connected to the low potential of said power source.

2. A voltage convertion system according to claim 1, in which said one type and said another type of said plurality of field effect transistors comprise a P-channel field effect transistor and a N-channel field effect transistor, respectively.

3. A voltage convertion system according to claim 2, further comprising a signal generator circuit coupled to the power source to generate an output signal, and in which said P-channel field effect transistor and said N-channel field effect transistor responsive to said output signal, respectively, for setting said plurality of capacitors into a parallel connected condition and a series connected condition.

4. A voltage conversion system according to claim 3, in which said signal generator circuit comprises an oscillator circuit coupled to the power source to provide said output signal.

5. A voltage conversion system according to claim 4, in which said oscillator circuit comprises a plurality of inverters coupled in a ring configuration.

6. A voltage conversion system according to claim 5, in which each of said inverters comprises complementary metal oxide semiconductor field effect transistors.

7. A voltage conversion system according to claim 6, in which said signal generator circuit further comprises a waveform shaping circuit coupled to said oscillator circuit to perform waveshaping of said output signal from said oscillator circuit.

8. A voltage conversion system according to claim 7, in which said waveform shaping circuit comprises a plurality of inverters connected in series.

9. A voltage conversion system according to claim 5, in which said oscillator circuit further comprises temperature sensing means coupled to said inverters for causing said oscillator circuit to serve as a temperature sensitive oscillator to generate an output signal at a frequency varying in dependence on ambient temperature.

10. A voltage conversion system according to claim 9, further comprising temperature compensation means coupled to a frequency standard and said oscillator circuit for automatically compensating changes in an output signal frequency of said frequency standard caused by said changes in temperature in dependence on a frequency of the output signal of said oscillator circuit.

11. A voltage conversion system according to claim 10, in which said temperature compensation means comprises means for generating an output signal of a frequency deviation proportional to a power of the value of any change in said ambient temperatue, and frequency summing means for generating an output signal of a frequency equal to the sum of frequencies of the output signals of said oscillator circuit, frequency standard and output signal generating means.

12. A voltage conversion system according to claim 11, in which said output signal generating means comprises a frequency squaring circuit which generates an output signal of a frequency proportional to the square of changes in the value of said ambient temperature above and below a preset specific temperature.

13. A voltage conversion system according to claim 12, in which said output signal generating means further comprises a frequency sampling circuit coupled to said frequency standard and said oscillator circuit and responsive to the output pulse signals from said frequency standard and the output signal from said oscillator circuit for thereby generating a sample output signal whose frequency is zero at said specific temperature and increases in proportion to the absolute value of any changes in said ambient temperature relative to said specific temperature value.

14. A voltage conversion system according to claim 13, in which said frequency squaring circuit comprises means for generating a plurality of pulse trains of different frequencies relative to one another, each having a frequency proportional to said sample output signal, frequency selecting means for selecting various combinations of said pulse trains, and frequency summing means for summing said selected combinations of pulse trains.

15. A voltage cnversion system according to claim 14, in which said frequency selecting means comprises means for generating various control signals in proportion to changes in frequency of said sample output signal.

16. A voltage conversion system according to claim 15, in which said control signal generating means comprises a counter circuit coupled to said sampling circuit and responsive to said sample output signal for generating said control signals.

17. A voltage conversion system according to claim 14, in which said means for generating said plurality of pulse trains comprises a counter circuit which counts continuously in response to an input signal of frequency proportional to that of said sample output signal.

18. A voltage conversion system according to claim 11, in which said temperature compensating means further comprises means for intermittently detecting said ambient temperature to provide a temperature information signal, and memory means for storing said temperature information signal.

19. A voltage conversion system according to claim 15, in which said frequency selecting means further comprises a matrix of logic AND gates coupled to said control signal generating means and said means for generating said plurality of pulse trains, said matrix selecting said various combinations of said pulse trains in response to said control signals.

20. A voltage conversion system according to claim 1, in which said power source comprises a lithium battery.

21. A voltage conversion system according to claim 1, in which said power source comprises a silver oxide battery.

22. A voltage conversion system according to claim 1, further comprising voltage stabilizing means coupled to said power source to stabilize the level of said lower output voltage, said voltage stabilizing means including first transistors as a reference voltage generator, and a second power controlling transistor coupled between said voltage conversion system and an output of said reference voltage generator.

23. A voltage conversion system according to claim 22, in which a threshold voltage of said first transistors is utilized as a reference voltage.

24. A voltage convertion system coupled to a power source to provide a lower output voltage than that of the power source, comprising:

a plurality of capacitors;

means for switching connections of said plurality of electric energy storage means relative to the power source for thereby providing said lower output voltage;

a buffer capacitor coupled to a terminal of the power source; and

a switching device coupled between said buffer capacitor and one of the output terminal of said switching means, said switching device coupling the output terminal of said switching means to said buffer capacitor only while said plurality of electric energy storage means are in a specific, present connected condition.

25. A voltage comvertion system coupled to a power source to provide a lower output voltage than that of the power source, comprising:

a plurality of capacitors;

means for switching connections of said plurality of electric energy storage means relative to the power source for thereby providing said lower output voltage;

a signal generator circuit coupled to the power source to generate an output signal;

said switching means responsive to said output signal for setting said plurality of electric energy storage means into a parallel connected condition and a series connected condition;

a voltage up converter circuit coupled to the power source to generate a higher output voltage than that of the power source, said voltage up converter circuit including a plurality of metal oxide field effect semiconductor transistors, a first capacitor coupled to a source terminal of one of said field effect transistors and coupled to a drain terminal of another of said field effect transistors, a source of boost switching signals, and a reservoir capacitor coupled to a terminal of the power source and to an output terminal of said voltage up converter circuit, wherein charge stored in said first capacitor by a first polarity of transitions of said boost switching signals is transferred to said reservoir capacitor by the action of a second polarity of transitions of said boost switching signal, causing one or more of said field effect transistors to pass from a high resistance state between drain and source terminals to a low resistance state.

26. A voltage convertion system according to claim 25, in which said boost switching signals are provided from said signal generator.

27. A voltage convertion system coupled to a lithium battery having high and low potentials, to provide a lower output voltage than that of the lithium battery, comprising:

a plurality of capacitors; and

a plurality of field effect transistors for switching connections of said plurality of capacitors relative to the lithium battery for thereby providing said lower output voltage, said plurality of field effect transistors including a P-channel field effect transistor having a source electrode connected to the high potential of said lithium battery and a drain electrode connected to said plurality of capacitors, and a N-channel field effect transistor having a source electrode connected to the low potential of said lithium battery and a drain electrode connected to said plurality of capacitors.

28. A voltage convertion system according to claim 27, further comprising a signal generator circuit coupled to the lithium battery to generate an output signal, and in which said P-channel field effect transistor and said N-channel field effect transistor have gate electrodes connected to said signal generator, said P-channel field effect transistor and said N-channel field effect transistor being responsive to the output signal for setting said plurality of capacitors into a parallel connected condition and a series connected condition.