Electronic watch and method of charging the same

• US 5,835,457 A
• Filed: 01/06/1997
• Issued: 11/10/1998
• Est. Priority Date: 01/03/1997
• Status: Expired due to Term

• Current Assignee: Citizen Holdings Co., Ltd. (Citizen Electronics Company Limited)
• Original Assignee: Citizen Watch Co Limited (Citizen Electronics Company Limited)
• Inventors: Nakajima, Fumio
• Primary Examiner(s): Roskoski, Bernard
• Application Number:
  US08/778,777
• Time in Patent Office: 673 Days
• Field of Search: 368/205, 368/204, 368/203
• US Class Current: 368/204
• CPC Class Codes: G04C 10/00 Arrangements of electric power supplies in time pieces circuits G04G19/00; mounting, assembling of components of electromechanical watches G04C3/008, of electronic watches G04G17/00
• CPC Class Codes: G04G 19/02 Conversion or regulation of current or voltage

Abstract

The electronic watch according to the invention comprises an energy source 1 (power supply), storage circuit 3, clock output unit 4, constant voltage circuit 5, voltage detection circuit 6, switching circuit 8, and control unit. The energy source 1 transforms external energy into electric energy and supplies a power supply voltage. The storage circuits 3 stores the power supply voltage or a booster voltage of the power supply voltage and thereby supplies a storage voltage. The clock output unit has a watch system and a condenser of a small capacitance, receives any of the power supply voltage or the booster voltage, and the storage voltage, and supplies a plurality of logic signals. The constant voltage circuit 5 generates a reference voltage from the clock voltage. The voltage detection circuit 6 compares the power supply voltage or booster voltage, storage voltage, and clock voltage selectively with a voltage set on the basis of the reference voltage and supplies a voltage detection signal. The switch circuit 8 is provided with a plurality of switches for controlling charging times of the storage circuit and the clock output unit. The control unit controls the switching circuit 8 by a plurality of pulse width variable switch control signals corresponding to a plurality of the logic signals and the voltage detection signal.

Claims

1. An electronic watch comprising:

an energy source that transforms an external energy into an electric energy and supplies a power supply voltage;

a booster circuit to generate a booster voltage from the power supply voltage;

a storage means for storing the power supply voltage or the booster voltage of the power supply voltage to supply a storage voltage;

a clock output means that has a watch system and a condenser of a small capacitance, that receives any of the power supply voltage or the booster voltage, and the storage voltage as a clock voltage, and supplies a plurality of logic signals;

a constant voltage circuit for generating a reference voltage from the clock voltage;

a voltage detection circuit that compares the power supply voltage or the booster voltage, the storage voltage, and the clock voltage selectively with a voltage set on the basis of the reference voltage and supplies a voltage detection signal;

a switching means provided with a plurality of switches, for controlling charging times of the storage means and the clock output means; and

a control means for controlling the switching means corresponding to a plurality of the logic signals and the voltage detection signal so that the charging time of the condenser of the clock output means becomes longer stepwise and the charging time of the storage means becomes shorter stepwise at a starting time of the clock system, and the charging time of the condenser of the clock output means becomes shorter stepwise and the charging time of the storage means becomes longer stepwise at a normal operation of the clock system.

2. An electronic watch according to claim 1, wherein:

the control means has a voltage detection control circuit that supplies a plurality of selection signals and data signals for setting a voltage to the voltage detection circuit, and

the voltage detection circuit comprises;

a voltage dividing circuit comprised of transmission gates for selecting any one of the power supply voltage or the booster voltage, the storage voltage, and the clock voltage corresponding to a plurality of the selection signals entering from the control means, and resistors for dividing the voltage selected thereby;

a D/A converter that converts the data signals (digital signals) entering from the control means into analog signals on the basis of the reference voltage from the constant voltage circuit and sets a voltage to be compared with a voltage selected by the voltage dividing circuit; and

a comparator that compares the voltage set by the D/A converter with the voltage selected and divided by the voltage dividing circuit and supplies the voltage detection signal.

3. An electronic watch as claimed in claim 1, wherein:

the clock output means supplies a plurality of the logic signals, when the power supply voltage generated by the energy source becomes a specific level of voltage;

by means of the logic signals, the control means supplies a plurality of selection signals and data signals to the voltage detection circuit;

the voltage detection circuit selects any one of the power supply voltage, the booster voltage, the storage voltage, and the clock voltage corresponding to the selection signals, compares the selected voltage with a voltage set on the basis of the data signals and the reference voltage, and supplies the voltage detection signal corresponding to the magnitude of the voltages;

the control means supplies a plurality of switch control signals to the switching means corresponding to the voltage detection signal and the logic control signals;

by means of the switch control signals, the switching means switches a plurality of the switches ON/OFF to control the charging times of the storage means and the clock output means.

4. An electronic watch as claimed in claim 2, wherein:

the clock output means supplies a plurality of the logic signals, when the power supply voltage generated by the energy source becomes a specific level of voltage;

by means of the logic signals, the voltage detection control circuit of the control means supplies a plurality of the selection signals and the data signals to the voltage detection circuit;

the voltage dividing circuit selects any one of the power supply voltage or the booster voltage, the storage voltage, and the clock voltage by the transmission gates corresponding to the selection signals, and divides the voltage selected thereby;

the D/A converter converts the data signals into analog signals based on the reference voltage to set a voltage;

the comparator compares the selected and divided voltage with the set voltage, and supplies the voltage detection signal corresponding to the magnitude of the voltages;

the control means supplies a plurality of switch control signals to the switch means corresponding to the voltage detection signal and the logic control signals; and

by means of the switch control signals, the switching means switches a plurality of the switches ON/OFF to control the charging times of the storage means and the clock output means.

5. An electronic watch, comprising:

an energy source that transforms an external energy into an electric energy and supplies a power supply voltage;

a booster circuit to generate a booster voltage from the power supply voltage;

a storage means for storing the power supply voltage or the booster voltage of the power supply voltage to supply a storage voltage;

a clock output means that has a watch system and a condenser of a small capacitance, that receives any of the power supply voltage or the booster voltage, and the storage voltage as a clock voltage, and supplies a plurality of logic signals;

a constant voltage circuit for generating a reference voltage from the clock voltage;

a voltage detection circuit that compares the power supply voltage or the booster voltage, the storage voltage, and the clock voltage selectively with a voltage set on the basis of the reference voltage and supplies a voltage detection signal;

a switching means provided with a plurality of switches, for controlling charging times of the storage means and the clock output means; and

a control means for controlling the switching means corresponding to a plurality of the logic signals and the voltage detection signal, wherein the control means is provided with a switch control circuit that has a pulse width control circuit, and supplies a plurality of pulse width variable switch control signals to the switching means for controlling the charging times of the storage means and the clock output means by receiving the logic signals from the clock output means and the voltage detection signal from the voltage detection circuit.

6. An electronic watch according to claim 5, wherein the switch control circuit of the control means supplies, as a plurality of the switch control signals, a first, a second, a third, and a fourth switch control signal to the switch means, wherein the switching means comprises:

a first switch connected between a terminal of the booster voltage and a terminal of the storage voltage, controlled to be ON/OFF by the first switch control signal;

a second switch connected between a terminal of the storage voltage and a terminal of the clock voltage, controlled to be ON/OFF by the second switch control signal;

a third switch connected between a terminal of the booster voltage and a terminal of the clock voltage, controlled to be ON/OFF by the third switch control signal;

a fourth switch connected between a terminal of the power supply voltage and a terminal of the clock voltage, controlled to be ON/OFF by the fourth switch control signal; and

a diode for preventing a backflow, connected in parallel with the fourth switch.

7. An electronic watch as claimed in claim 5, wherein:

the clock output means supplies a plurality of the logic signals, when the power supply voltage generated by the energy source becomes a specific level of voltage;

by means of the logic signals, the voltage detection control circuit of the control means supplies a plurality of the selection signals and the data signals to the voltage detection circuit;

the voltage detection circuit selects any one of the power supply voltage or the booster voltage, the storage voltage, and the clock voltage corresponding to the selection signals, and compares the selected voltage with a voltage set on the basis of the data signal and the reference voltage, and supplies the voltage detection signal corresponding to the magnitude of the voltages;

the control means supplies a plurality of pulse width variable switch control signals from the switch control circuit, corresponding to the voltage detection signal and the logic control signals; and

by means of a plurality of the switch control signals, the switching means controls the charging times of the storage means and the clock output means so that the charging time of the condenser of the clock output means becomes longer stepwise and the charging time of the storage means becomes shorter stepwise at a starting time of the clock system, and the charging time of the condenser of the clock output means becomes shorter stepwise and the charging time of the storage means becomes longer stepwise at a normal operation of the clock system.

8. An electronic watch as claimed in claim 6, wherein:

the clock output means supplies a plurality of the logic signals, when the power supply voltage generated by the energy source becomes a specific level of voltage;

by means of the logic signals, the voltage detection control circuit of the control means supplies a plurality of the selection signals and the data signals to the voltage detection circuit;

the voltage detection circuit selects any one of the power supply voltage or the booster voltage, the storage voltage, and the clock voltage corresponding to the selection signals, and compares the selected voltage with a voltage set on the basis of the data signal and the reference voltage, and supplies the voltage detection signal corresponding to the magnitude of the voltages;

the control means supplies the first, the second, the third, and the fourth switch control signal for controlling the switching means from the switch control circuit corresponding to the voltage detection signal and the logic signals; and

by means of the first, the second, the third, and the fourth switch control signal, the switching means switches the first, the second, the third, and the fourth switch ON/OFF to control the charging times of the storage means and the clock output means so that the charging time of the condenser of the clock output means becomes longer than the charging time of the storage means at a starting time of the clock system and the charging time of the storage means becomes longer than the charging time of the condenser of the clock output means at a normal operation of the clock system, and the diode for preventing a backflow is in connection between the terminal of the power supply voltage and the terminal of the clock voltage when the fourth switch is turned OFF.

9. An electronic watch as claimed in claim 8, wherein, when the switch control circuit of the control means determines from the voltage detection signal and the logic signals that the storage voltage is lower than a preset level, the fourth switch control signal turns ON the fourth switch of the switch means to short-circuit the diode for preventing the backflow.

10. An electronic watch as claimed in claim 8, wherein, when the switch control circuit of the control means determines from the voltage detection signal and the logic signals that the storage voltage is higher than the preset level, the second switch control signal turns ON the second switch of the switch means and the fourth switch control signal turns OFF the fourth switch of the switch means.

11. An electronic watch comprising:

an energy source that transforms an external energy into an electric energy and supplies a power supply voltage;

a storage means for storing the power supply voltage to supply a storage voltage;

a clock output means that has a watch system and a condenser of a small capacitance, that receives the power supply voltage or the storage voltage as a clock voltage, and supplies a plurality of logic signals;

a constant voltage circuit for generating a reference voltage from the clock voltage;

a voltage detection circuit that compares the power supply voltage or the storage voltage, and the clock voltage selectively with a voltage set on the basis of the reference voltage and supplies a voltage detection signal;

a switching means provided with a plurality of switches, for controlling charging times of the storage means and the clock output means; and

a control means for controlling the switching means corresponding to a plurality of the logic signals and the voltage detection signal so that the charging time of the condenser of the clock output means becomes longer stepwise and the charging time of the storage means becomes shorter stepwise at a starting time of the clock system, and the charging time of the condenser of the clock output means becomes shorter stepwise and the charging time of the storage means becomes longer stepwise at a normal operation of the clock system.

12. An electronic watch as claimed in claim 11, wherein:

the clock output means supplies a plurality of the logic signals, when the power supply voltage generated by the energy source becomes a specific level of voltage;

by means of the logic signals, the control means supplies a plurality of selection signals and data signals to the voltage detection circuit;

the voltage detection circuit selects any one of the power supply voltage, the storage voltage, and the clock voltage corresponding to the selection signals, compares the selected voltage with a voltage set on the basis of the data signals and the reference voltage, and supplies the voltage detection signal corresponding to the magnitude of the voltages;

the control means supplies a plurality of switch control signals to the switching means corresponding to the voltage detection signal and the logic control signals;

by means of the switch control signals, the switching means switches a plurality of the switches ON/OFF to control the charging times of the storage means and the clock output means.

13. An electronic watch according to claim 11, wherein:

the control means has a voltage detection control circuit that supplies a plurality of selection signals and data signals for setting a voltage to the voltage detection circuit, and

the voltage detection circuit comprises;

a voltage dividing circuit comprised of a transmission gates for selecting any one of the power supply voltage or the storage voltage, and the clock voltage corresponding to a plurality of the selection signals entering from the control means, and resistors for dividing the voltage selected thereby;

a D/A converter that converts the data signals (digital signals) entering from the control means into analog signals on the basis of the reference voltage from the constant voltage circuit and sets a voltage to be compared with a voltage selected by the voltage dividing circuit; and

a comparator that compares the voltage set by the D/A converter with the voltage selected and divided by the voltage dividing circuit and supplies the voltage detection signal.

14. An electronic watch as claimed in claim 13, wherein:

the clock output means supplies a plurality of the logic signals, when the power supply voltage generated by the energy source becomes a specific level of voltage;

by means of the logic signals, the voltage detection control circuit of the control means supplies a plurality of the selection signals and the data signals to the voltage detection circuit;

wherein;

the voltage dividing circuit selects any one of the power supply voltage or the storage voltage, and the clock voltage by the transmission gates corresponding to the selection signals, and divides the voltage selected thereby;

the D/A converter converts the data signals into analog signals based on the reference voltage to set a voltage;

the comparator compares the selected and divided voltage with the set voltage, and supplies the voltage detection signal corresponding to the magnitude of the voltages;

the control means supplies a plurality of switch control signals to the switch means corresponding to the voltage detection signal and the logic control signals; and

by means of the switch control signals, the switching means switches a plurality of the switches ON/OFF to control the charging times of the storage means and the clock output means.

15. An electronic watch, comprising:

an energy source that transforms an external energy into an electric energy and supplies a power supply voltage;

a storage means for storing the power supply voltage supply voltage to supply a storage voltage;

a clock output means that has a watch system and a condenser of a small capacitance, that receives the power supply voltage or the storage voltage as a clock voltage, and supplies a plurality of logic signals;

a constant voltage circuit for generating a reference voltage from the clock voltage;

a voltage detection circuit that compares the power supply voltage or the storage voltage, and the clock voltage selectively with a voltage set on the basis of the reference voltage and supplies a voltage detection signal;

a switching means provided with a plurality of switches, for controlling charging times of the storage means and the clock output means; and

a control means for controlling the switching means corresponding to a plurality of the logic signals and the voltage detection signal,

wherein the control means is provided with a switch control circuit that has a pulse width control circuit, and supplies a plurality of pulse width variable switch control signals to the switching means for controlling the charging times of the storage means and the clock output means by receiving the logic signals from the clock output means and the voltage detection signal from the voltage detection circuit.

16. An electronic watch according to claim 15, wherein the switch control circuit of the control means supplies, as a plurality of the switch control signals, a first and a second switch control signal to the switch means, wherein the switching means comprises:

a first switch connected between a terminal of the storage voltage and a terminal of the clock voltage, controlled to be ON/OFF by the first switch control signal;

a second switch connected between a terminal of the power supply voltage and a terminal of the clock voltage, controlled to be ON/OFF by the second switch control signal; and

a diode for preventing a backflow, connected in parallel with the second switch.

17. An electronic watch as claimed in claim 15, wherein:

the clock output means supplies a plurality of the logic signals, when the power supply voltage generated by the energy source becomes a specific level of voltage;

by means of the logic signals, the voltage detection control circuit of the control means supplies a plurality of the selection signals and the data signals to the voltage detection circuit;

the voltage detection circuit selects any one of the power supply voltage or the storage voltage, and the clock voltage corresponding to the selection signals, and compares the selected voltage with a voltage set on the basis of the data signal and the reference voltage, and supplies the voltage detection signal corresponding to the magnitude of the voltages;

the control means supplies a plurality of pulse width variable switch control signals from the switch control circuit, corresponding to the voltage detecting signal and the logic control signals; and

by means of plurality of the switch control signals, the switching means controls the charging times of the storage means and the clock output means so that the charging time of the condenser of the clock output means becomes longer stepwise and the charging time of the storage means becomes shorter stepwise at a starting time of the clock system, and the charging time of the condenser of the clock output means becomes shorter stepwise and the charging time of the storage means becomes longer stepwise at a normal operation of the clock system.

18. An electronic watch as claimed in claim 16, wherein:

the clock output means supplies a plurality of the logic signals, when the power supply voltage generated by the energy source becomes a specific level of voltage;

by means of the logic signals, the voltage detection control circuit of the control means supplies a plurality of the selection signals and the data signals to the voltage detection circuit;

the voltage detection circuit selects any one of the power supply voltage or the storage voltage, and the clock voltage corresponding to the selection signals, and compares the selected voltage with a voltage set on the basis of the data signal and the reference voltage, and supplies the voltage detection signal corresponding to the magnitude of the voltages;

the control means supplies the first and the second switch control signal for controlling the switching means from the switch control circuit corresponding to the voltage detection signal and the logic signals; and

by means of the first and the second switch control signals, the switching means switches the first and the second switch ON/OFF to control the charging times of the storage means and the clock output means so that the charging time of the condenser of the clock output means becomes longer than the charging time of the storage means at a starting time of the clock system and the charging time of the storage means becomes longer than the charging time of the condenser of the clock output means at a normal operation of the clock system, and the diode for preventing a backflow is in connection between the terminal of the power supply voltage and the terminal of the clock voltage when the second switch is turned OFF.

19. An electronic watch as claimed in claim 18, wherein, when the switch control circuit of the control means determines from the voltage detection signal and the logic signals that the storage voltage is higher than the present level, the first switch control signal turns ON the first switch of the switch means and the second switch control signal turns OFF the second switch of the switch means.

20. An electronic watch as claimed in claim 18, wherein, when the switch control circuit of the control means determines from the voltage detection signal and the logic signals that the storage voltage is lower than a present level, the second switch control signal turns ON the second switch of the switch means to short-circuit the diode for preventing the backflow.

21. A method of charging an electronic watch, comprising the steps of:

transforming an external energy into an electric energy supplying a power supply voltage;

boosting the power supply voltage to supply a booster voltage;

storing the power supply voltage or the booster voltage in a storage means to supply a storage voltage;

providing a clock voltage to a clock output means, having a watch system and a condenser of a small capacitance, from at least one of the power supply voltage, the booster voltage, and the storage voltage;

generating a plurality of logic signals from the clock output means;

supplying a reference voltage from the clock voltage;

comparing at least one of the power supply voltage, the booster voltage, and the storage voltage with a voltage set on the basis of the reference voltage to generate a voltage detection signal corresponding to the magnitude of the voltages;

controlling charging times of the storage means and the clock output means based on switches controlled by the logic signals and the voltage detection signal, so that the charging time of the condenser of the clock output means becomes longer stepwise and the charging time of the storage means becomes shorter stepwise at a starting time of the clock system, and the charging time of the condenser of the clock output means becomes shorter stepwise and the charging time of the storage means becomes longer stepwise at a normal operation of the clock system.

22. A method of charging an electronic watch, comprising the steps of:

transforming an external energy into an electric energy supplying a power supply voltage;

storing the power supply voltage in a storage means to supply a storage voltage;

providing a clock voltage to a clock output means, having a watch system and a condenser of a small capacitance, from the power supply voltage or the storage voltage;

generating a plurality of logic signals from the clock output means;

supplying a reference voltage from the clock voltage;

comparing the power supply voltage or the storage voltage with a voltage set on the basis of the reference voltage to generate a voltage detection signal corresponding to the magnitude of the voltages;

controlling charging times of the storage means and the clock output means based on switches controlled by the logic signals and the voltage detection signal, so that the charging time of the condenser of the clock output means becomes longer stepwise and the charging time of the storage means becomes shorter stepwise at a starting time of the clock system, and the charging time of the condenser of the clock output means becomes shorter stepwise and the charging time of the storage means becomes longer stepwise at a normal operation of the clock system.