Horology: time measuring systems or devices – Chronological – With supplemental power source
Reexamination Certificate
1999-12-13
2002-01-29
Miska, Vit (Department: 2859)
Horology: time measuring systems or devices
Chronological
With supplemental power source
C368S066000, C368S204000
Reexamination Certificate
active
06343051
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a portable electronic device and a control method for the portable electronic device, and more specifically, it relates to a power supply control technique in an electronically controlled portable timepiece that incorporates a power generating mechanism.
2. Description of the Related Art
Recently, small-sized electronic timepieces in the form of, e.g., wristwatches have been developed. These timepieces incorporate a power generator such as a solar cell and operate without replacing batteries. These electronic timepieces charge large-capacitance capacitors with electric power generated by power generators, and indicate the time of day with the power discharged from the capacitors when power is not generated. These electronic timepieces can therefore operate stabily for a long time without batteries. Given the inconvenience of replacing batteries and problems incidental to disposal of exhausted batteries, it is expected that power generators will be incorporated in more and more electronic timepieces in the future.
In such an electronic timepiece incorporating a power generator, a limiter circuit for limiting a source voltage is provided to prevent a voltage generated by the power generator from exceeding the voltage tolerance level of a power supply unit having an electricity accumulating function, e.g., a large-capacitance capacitor, or to prevent a source voltage applied from the power supply unit to a time indicating circuit from exceeding the voltage tolerance level of the time indicating circuit.
In order to prevent a voltage generated by the power generator from exceeding the voltage tolerance level of the power supply unit, or prevent a source voltage applied from the power supply unit to the time indicating circuit from exceeding the withstanding voltage tolerance level of the time indicating circuit, the limiter circuit operates to electrically disconnect the power supply unit from the power generator at a point upstream of the power supply unit, or electrically disconnects the power supply unit from the time indicating circuit at a point downstream of the power supply unit, or short-circuits the output terminals of the power supply unit to prevent the generated voltage from being transmitted to downstream components.
However, in order to provide a stable power supply, an electronic timepiece incorporating a power generator is constructed such that when the power generator does not generate power for a predetermined time or longer, this condition is detected to shift the operation mode from a normal operation mode (indicating mode) in which the time of day is indicated, to a power-saving mode in which the time of day is not indicated.
Operating the limiter circuit requires a voltage detecting circuit for detecting the applied voltage, and the voltage detecting circuit increases power consumption. Particularly, when the voltage detecting circuit is constructed of a circuit for detecting voltage with high precision, there arises a problem of increasing both the circuit scale and power consumption.
Further, in order to prolong the operating time, an electronic timepiece incorporating a power generator includes a voltage step-up circuit for stepping up a source voltage to produce voltages for driving downstream circuits. However, unless a step-up factor of the voltage step-up circuit is correctly set, a voltage exceeding the voltage value suitable for operation or the absolute rated voltage is applied to the circuits, and in the worst case, the electronic timepiece would be damaged.
OBJECTS OF THE INVENTION
Therefore, it is an object of the present invention to overcome the aforementioned problems.
Accordingly, the object of the present invention is to realize a reliable power supply control function in a portable electronic device which includes a limiter circuit for limiting a source voltage, or includes the limiter circuit and a voltage step-up circuit, and to provide a portable electronic device and a control method for the portable electronic device with which power consumption can be reduced.
SUMMARY OF THE INVENTION
To solve the problems set forth above, a portable electronic device according to the present invention comprises a power generator or generating means for generating power through conversion from first energy to second energy in the form of electrical energy; a power supply or power supply means for accumulating the electrical energy produced by the power generation; a for accumulating the electrical energy produced by the power generation; a driven unit or means driven with the electrical energy supplied from the power supply; a power-generation detector or detecting means for detecting whether or not power is generated by the power generator; limiter-ON-voltage detector or detecting means for detecting whether or not a voltage generated by the power generator or a voltage accumulated in the power supply exceeds a preset limiter-ON voltage; a limiter or limiter means for limiting the voltage of the electrical energy to be supplied to the power supply to a predetermined reference voltage set in advance when it is determined, based on a detection result of the limiter-ON-voltage detector, that the voltage generated by the power generator or the voltage accumulated in the power supply has not been reduced below the preset limiter-ON voltage; and limiter-ON-voltage detection prohibiting unit or means for prohibiting the detecting operation of the limiter-ON-voltage detector when it is determined, based on a detection result of the power-generation detector, that power is not generated by the power generating means.
Also, the limiter-ON-voltage detection prohibiting unit may include an operation stopping unit or means for stopping operation of the limiter-ON-voltage detector to prohibit the detecting operation of the limiter-ON-voltage detector.
In addition, the portable electronic device may further comprise a generated-voltage detector or detecting means for detecting a voltage generated by the power generator, and the limiter-ON-voltage detection prohibiting unit may include a limiter-ON-voltage detection controller or control means for prohibiting the detecting operation of the limiter-ON-voltage detector when it is determined, based on a detection result of the generated-voltage detector, that the generated voltage does not exceed a predetermined limiter control voltage that is lower than the limiter-ON voltage, and allowing the detecting operation of the limiter-ON-voltage detector when the generated voltage exceeds the predetermined limiter control voltage.
Further, the portable electronic device according to the present invention may further comprise a limiter-ON unit or means for bringing the limiter into an operative state when it is determined, based on the detection result of the limiter-ON-voltage detector, that the voltage generated by the power generator or the voltage accumulated in the power supply has exceeded the preset limiter-ON voltage; and an operating-state controller or control means for bringing the limiter into an inoperative state when the limiter is in the operative state, and also when it is determined, based on the detection result of the power-generation detector, that power is not generated by the power generator or when it is determined, based on the detection result of the generated-voltage detector, that the generated voltage does not exceed the predetermined limiter control voltage that is lower than the limiter-ON voltage.
Also, the limiter-ON-voltage detector detects whether or not the voltage accumulated in the power supply means exceeds the preset limiter-ON voltage, with a cycle not larger than the cycle necessary for detecting a change of the voltage generated by the power generator.
A portable electronic device according to the present invention comprises a power generator or generating means for generating power through conversion from first energy to second energy in the form of electrical energy; a power supply or power suppl
Okeya Makoto
Yabe Hiroshi
Miska Vit
Seiko Epson Corporation
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