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.
An electronic apparatus includes a power generator (20) as a power supply, a capacitor (30) for accumulating generated power, a logic circuit (170) driven by the power from the capacitor, and a power supply cut-off circuit (31). When the power generator starts operating,the power supply cut-off circuit (31) does not supply power to the logic circuit (170) until a voltage of the capacitor (30) reaches a preset voltage. When the voltage of the capacitor (3) becomes equal to or greater than the preset voltage, power is supplied from the capacitor to the logic circuit. Accordingly, a leakage current when power generation starts is prevented, and most of the generated power is accumulated in the capacitor. The capacitor, can rapidly accumulate electricity, and the time until activation of an electronic circuit driven by the capacitor is reduced.
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.
In an electronic timepiece using power supply means consisting of a solar cell and an electric double layer capacitor, whose output voltage varies, as a power supply, a plurality of driving pulse preparation means for preparing driving pulses for driving a stepping motor are arranged. Each driving pulse preparation means prepares a driving pulse group having a combination of pulse widths, which combination is different from that of remaining ones of the driving pulse preparation means. A varying output voltage of the power supply means is detected, and one of the plurality of driving pulse preparation means is selected in accordance with the detected output voltage. A driving pulse for minimizing the current consumption is selected and supplied to the drive circuit of the stepping motor. With this arrangement, the stepping motor can always be driven at a minimum current consumption, and the driving time can be prolonged.
A compact and thin electronic control timepiece having a long duration time for indicating highly accurate time. The flow of an AC electromotive force induced in a coil in a generator powered by a power spring is supplied to a step-up circuit in an IC. The step-up circuit boosts the rectified electromotive force doubling to charge in a smoothing capacitor as storage power. A step-up control circuit generates a step-up control signal for controlling the step-up operation of the step-up circuit. A cycle comparing circuit compares a reference cycle signal from an oscillation circuit and a detected cycle signal synchronized with the rotational cycle of the generator, generates a cycle correction signal for eliminating a time difference between both signals, and outputs the signal to a load control circuit. The load control circuit in turn changes a load current on the generator by appropriately selecting a load resistor for changing switching elements within an internal circuit, controls the amount of an electromagnetic brake corresponding to a current amount flowing through the load resister and thereby governs the speed of the rotation cycle of the generator.
An electronic device, in a preferred embodiment an electronic watch, including a power generating device, a secondary power source for storing generated electric energy fed from the power generating device and serving as the power source for the electronic device, a first boosting circuit for stepping up the voltage of the secondary power source, a second boosting circuit, and a capacitor connected to the output of the first boosting circuit and charged through the output of the first boosting circuit, for stepping up the voltage of the capacitor. A voltage level converter converts a control signal based on the first boosting circuit output voltage to a control signal based on the second boosting circuit output to at least in part control the operation of the first boosting circuit. In this manner, the boosting circuits control the operation of the device such that when the voltage lever is low or the voltage level reaches a certain point the device does not shut down, but rather maintains normal operation.
