Horology: time measuring systems or devices – Chronological – With supplemental power source
Reexamination Certificate
2000-08-03
2002-10-15
Miska, Vit (Department: 2841)
Horology: time measuring systems or devices
Chronological
With supplemental power source
C368S066000, C368S204000
Reexamination Certificate
active
06466519
ABSTRACT:
TECHNICAL FIELD
The present invention relates to an electronic apparatus, to an electronically-controlled timepiece having the same, and to a power supply control method.
BACKGROUND ART
Concerning an electronically-controlled mechanical timepiece for displaying accurate time, there is a known timepiece described in Japanese Unexamined Patent Application Publication No. 8-5758. In this timepiece, mechanical energy when releasing a spring is converted into electrical energy by a power generator. A rotation control unit is activated by the electrical energy, and a current value flowing through a coil of the power generator is controlled. Hence, hands fixed to a wheel train are accurately driven, thus displaying accurate time.
In this timepiece, the electrical energy from the power generator, that is, the power supply for supplying electrical energy, is supplied to a capacitor once, and power from the capacitor is employed to drive the rotation control unit. Since AC electromotive force in synchronism with a rotation period of the power generator is input to the capacitor, it is not necessary to store power for enabling the rotation control unit provided with an IC (an electronic circuit and a logic circuit) and an oscillation circuit (quartz crystal oscillator) to operate for a long period of time. Hence, a capacitor with a relatively small capacitance, such as a 10 &mgr;F capacitor, capable of operating the IC and the oscillation circuit for a few seconds is employed.
This electronically-controlled mechanical timepiece does not require a motor since it uses the spring as a power source for driving the hands. Therefore, the characteristics of the timepiece are that it requires a few components and is inexpensive. In addition, it is only necessary to generate small electrical energy for driving the electronic circuit. The timepiece can be operated by small input energy.
However, this conventional electronically-controlled mechanical timepiece has drawbacks as follows. Specifically, when performing time adjustment (hands adjustment) which is generally performed by pulling out a crown, hands for hour, minute, and second are stopped so that the time can be accurately adjusted. Since stopping the hands would mean stopping the wheel train, the power generator is also stopped.
Therefore, the input of electromotive force from the power generator to the capacitor is stopped. In contrast, the IC and the oscillation circuit are continuously driven. Electrical charges accumulated in the capacitor are discharged to the IC side, thus reducing a terminal voltage. As a result, the rotation control unit, that is, the oscillation circuit or the like, is also stopped.
When the IC stops oscillating, power consumption is reduced, thus significantly slowing down voltage reduction in the capacitor. When a user has trouble in adjusting the time, and a voltage of the capacitor is reduced below an oscillation stopping voltage, the capacitor is often at a voltage of approximately 0.3 to 0.4 V which is slightly smaller than the oscillation stopping voltage. When the time adjustment (hands adjustment) is performed for a very long period of time, such as for more than several tens of minutes, the capacitor may completely discharge, and the voltage may be reduced to “0”.
When the hands adjustment is completed and the crown is pushed in, thus starting rotation of the power generator, some time is required to boost the voltage of the capacitor by a charging current of the power generator and to cause the oscillation circuit and the IC to start operating. In particular, when a generated current is small, power is consumed by a leakage in the IC, and the voltage of the capacitor is not increased. Hence, the system is not promptly started. This results in taking time to start brake control and to perform time control. Although the time adjustment (hands adjustment) is performed, there is an error in the designated time.
Besides the electronically-controlled mechanical timepiece, a self-winding generating-type timepiece for moving an oscillating weight and generating power, and an electrically-controlled timepiece, such as a solar rechargeable-type timepiece, provided with various generators (power supplies) have a similar problem. When a power generator is stopped upon hands adjustment, and when a capacitor is discharged, some time is required to activate electronic circuits due to a leakage in the IC or the like, even when the power generator is activated.
Besides the electrbnically-controlled timepiece, there are various electronic apparatuses provided with a power generator (power supply), a capacitor, and electronic circuits such as an IC and an oscillation circuit. In addition, there are various electrical apparatuses provided with, instead of a power generator, a power supply such as a commercial power supply or a car battery. Concerning these electrical apparatuses, there is a problem in that, when the power supply starts operating, that is, when the power generator is started or when power is first supplied from the power supply, some time is required to activate the IC and the oscillation circuit, due to a leakage in the IC or the like.
It is an object of the present invention to provide an electronic apparatus, an electronically-controlled timepiece, and a power supply control method in which electronic circuits, such as an IC and an oscillation circuit, are rapidly activated when a power supply starts operating.
DISCLOSURE OF INVENTION
An electronic apparatus according to the present invention, including a power supply, a capacitor for accumulating power from the power supply, and an electronic circuit driven by the power from the capacitor, comprises a power supply control unit for not supplying the power from the capacitor to the electronic circuit until a voltage of the capacitor reaches a preset voltage, and for supplying the power from the capacitor to the electronic circuit when the voltage of the capacitor becomes equal to or greater than the preset voltage.
According to the present invention, the power supplied from the power supply, such as a power generator, is accumulated in the capacitor. Since the power supply control unit controls the power not to be supplied from the capacitor to the electronic circuit until the voltage of the capacitor reaches the preset value, a leakage current is not generated, which is part of the power supplied from the power supply flowing into the electronic circuit. Most of the supplied power (generated power or the like) can be supplied to the capacitor. Therefore, the time required to increase the voltage of the capacitor so as to reliably activate the electronic circuit, such as an IC, is reduced. The time until activation of the electronic circuit, such as the IC or an oscillation circuit, is reduced.
Due to characteristics of a quartz crystal oscillator, the quartz crystal oscillator oscillates more readily when a rapidly-changing voltage is suddenly applied, compared to when a gradually-increasing voltage is applied. In other words, the quartz crystal oscillator can oscillate even at a low voltage. By applying the voltage of the capacitor that has reached the preset voltage to the electronic circuit, a relatively large voltage can suddenly be applied to the electronic circuit. This reduces the oscillation starting time of a quartz crystal oscillating circuit of the electronic circuit.
The power supply may be a power generator. Preferably, when the power generator starts operating, the power supply control unit does not supply the power from the capacitor to the electronic circuit until the voltage of the capacitor reaches the preset voltage. Preferably, the power supply control unit supplies the power from the capacitor to the electronic circuit when the voltage of the capacitor becomes equal to or greater than the preset voltage.
Concerning the power supply, a commercial power supply or a car battery can be employed. Alternatively, various power generators can be employed, including a power generator for rotating a rotor and generating power by means of ele
Koike Kunio
Nakamura Hidenori
Shimizu Eisaku
Miska Vit
Seiko Epson Corporation
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