Horology: time measuring systems or devices – Power supply details – Electrical
Reexamination Certificate
2001-01-25
2004-09-21
Miska, Vit W. (Department: 2841)
Horology: time measuring systems or devices
Power supply details
Electrical
C322S008000, C322S024000, C322S029000
Reexamination Certificate
active
06795378
ABSTRACT:
TECHNICAL FIELD
The present invention relates to an electronic device, an electronically controlled mechanical timepiece, and a control method therefore, and more particularly, to an electronic device having a mechanical energy source, a generator that is driven by the mechanical energy source, generates induced electric power, and outputs electrical energy, an electric storage unit for storing the electrical energy output from the generator, and a rotation control unit that is driven by the electrical energy supplied from the electric storing unit and controls the rotation cycle of the generator; an electronically controlled mechanical timepiece; and a control method therefor.
BACKGROUND ART
As an electronically controlled mechanical timepiece that converts the mechanical energy produced when a mainspring is unwound into electrical energy by a generator, uses the electrical energy to actuate a rotation control unit so as to control the value of a current passing through a coil of the generator, thereby accurately driving the hands fixed to a wheel train to accurately display time, there has been known an electronically controlled mechanical timepiece disclosed in Japanese Examined Patent Application Publication No. 7-119812.
In the invention disclosed in the Japanese Examined Patent Application Publication No. 7-119812, brake-OFF control is conducted at each of a plurality of first time points that periodically take place at the cycle of a reference signal from a crystal oscillator or the like, and brake-ON control is conducted at a second time point spaced away the first time point in the cycle of the reference signal. The brake-ON control and the brake-OFF control are always carried out in one cycle of a reference cycle.
However, the brake-ON control begun at the second time point of a reference cycle is forcibly switched to the brake-OFF control at the first time point of the next reference cycle regardless of the rotation state of the generator. This has been posing a problem in that a sufficient brake amount cannot be supplied, depending on the state, and much time is required before speed control is completed.
Furthermore, in addition to the electronically controlled mechanical timepieces, in a variety of electronic devices, such as music boxes, metronomes, toys, and electric razors, that have components rotatively controlled by mechanical energy sources, such as springs or elastic, there has always been a demand for improved accuracy of moving parts, e.g., the operations of the drums of music boxes or the pendulums of metronomes, by conducting accurate brake control.
An object of the present invention is to provide an electronic device capable of applying an accurate and sufficient brake amount and of achieving improved responsiveness of speed control and stable control, an electronically controlled mechanical timepiece, and a control method therefor.
DISCLOSURE OF INVENTION
An electronic device of the present invention is equipped with a mechanical energy source, a generator that is driven by the mechanical energy source, generates induced electric power, and supplies electrical energy, and a rotation control unit that is driven by the electrical energy and controls a rotation cycle of the generator, wherein the rotation control unit is provided with a brake control unit that compares a reference signal issued based on a signal from a time standard source with a rotation detection signal based on the rotation cycle of the generator thereby to adjust a braking time of the generator, and a brake amount correcting unit for correcting the braking time set by the brake control unit on the basis of the rotation cycle of the generator.
At this time, preferably, the brake amount correcting unit corrects the braking time by making the braking time shorter than the time set by the brake control unit if the rotation cycle of the generator is later (or longer: the same will apply hereinafter) than a predetermined range based on the cycle of the reference signal.
The brake amount correcting unit may correct the braking time by making the braking time longer than the time set by the brake control unit if the rotation cycle of the generator is earlier (or shorter: the same will apply hereinafter) than the predetermined range.
Preferably, the brake amount correcting unit corrects the braking time by making the braking time shorter than the time set by the brake control unit if the rotation cycle of the generator is later than a predetermined range based on the cycle of the reference signal, or by making the braking time longer than the time set by the brake control unit if the rotation cycle of the generator is earlier than the predetermined range.
In the electronic device in accordance with the present invention, the generator is driven by a mechanical energy source, such as a spring, and the number of rotations of a rotor is controlled by applying a brake to the generator by a rotation control unit.
At this time, if the rotation cycle of the generator is close to the reference signal cycle, that is, if the rotation cycle is based on the reference signal cycle and stays within a predetermined range, then the brake control is carried out on the basis of the braking time set by the comparison between the reference signal and a rotation detection signal performed by the brake control unit.
Furthermore, if the rotation cycle of the generator significantly deviates from the reference signal cycle, then the braking time, i.e., the brake amount, is adjusted on the basis of the rotation cycle. For example, if the rotation cycle is shorter than the reference signal cycle, then the braking time is made longer than the time set at the brake control unit so as to suppress the rotational speed of the generator thereby causing the rotation cycle to quickly approach the reference signal. If the rotation cycle is longer than the reference signal cycle, then the rotational speed of the generator is increased by making the braking time shorter than the time set at the brake control unit so as to increase the rotational speed of the generator, thereby causing the rotation cycle to quickly approach the reference signal.
With this arrangement, optimum brake control is conducted on the basis of the rotation cycle of the generator regardless of the reference cycle; hence, a secure, sufficient brake amount is applied, and the responsiveness in speed control can be enhanced, as compared with the case where the brake-ON control and the brake-OFF control are always carried out in every cycle of the reference cycle. Thus, variations in the rotation cycle of a rotor of a generator can be reduced, allowing the generator to stably rotate at a substantially constant speed.
The time during which the brake amount correcting unit adjusts the braking time may be set, for example, in one level or more beforehand according to the rotation cycle of the generator, or may be set so that it is continuously changed according to the rotation cycle at that point.
The correction time for correcting the braking time may be in one level (fixed); however, setting the correction time in one level or more, preferably two levels or more, on the basis of the magnitude of the rotation cycle, i.e., the displacement from the reference cycle, makes it possible to bring the rotation cycle of the generator close to the reference cycle more quickly by extending the correction time even in case of a significant deviation from the reference cycle. Setting the correction time so that it is continuously changed according to the rotation cycle permits more detailed adjustment to be made.
Preferably, the brake control unit is provided with a count-up/down counter that receives one of the rotation detection signal and the reference signal as a count-up signal, receives the other as a count-down signal, and is configured so that if the value of the count-up/down counter is a set value or more, then a brake is applied to the generator, and if it is below the set value, then the brake applied to the generator is released.
Employing the count-up/down
Koike Kunio
Nakamura Hidenori
Shimizu Eisaku
Miska Vit W.
Seiko Epson Corporation
Watson Mark P.
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