Horology: time measuring systems or devices – Power supply details – Electrical
Reexamination Certificate
2002-03-22
2004-02-17
Martin, David (Department: 2841)
Horology: time measuring systems or devices
Power supply details
Electrical
C368S203000, C368S064000, C368S066000, C322S008000, C322S024000, C322S029000, C322S046000
Reexamination Certificate
active
06693852
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an electronic device, an electronically-controlled, mechanical timepiece, and an electronic device controlling method. More specifically, the present invention relates to such a device/timepiece which includes a mechanical energy source, a generator which is driven by the mechanical energy source and which generates induced electrical power and provides electrical energy, and a rotation controller which is driven by the electrical energy and which controls the rotation period of the generator. A method for so controlling an electronic device is also provided.
2. Description of the Related Art
Japanese Patent Publication No. 7-119812 discloses an electronically controlled, mechanical timepiece which presents precise time by accurately driving hands attached to a gear train. In this timepiece, a mainspring, when unwound, releases mechanical energy, which is converted into electrical energy by a generator. The electrical energy is then used to drive a rotation controller, which controls the current flowing through a coil of the generator.
In order to increase the duration of such an electronically-controlled, mechanical timepiece, it is important that, while a torque of the mainspring (mainspring torque) is high, a braking torque can be increased without reducing the power generated. More specifically, in the brake control of the generator, preferably, the braking torque is prioritized when the mainspring torque is high and power generation (electromotive force) is prioritized when the mainspring torque is low, that is, when a large braking force is not required. The torque (mainspring torque) is increased not only when the mainspring is wound by a large amount but also when a driving torque applied to a rotor is increased due to external shock such as oscillation, impact, etc. Similarly, the torque (mainspring torque) is increased not only when the mainspring is loose but also when the driving torque applied to the rotor is reduced due to the external shock.
Thus, according to the Japanese Patent Publication No. 7-119812, two angular ranges are provided in a single turn of a rotor, that is, in each period of a reference signal. In one angular range, a braking force is removed to increase the rotational speed of the rotor so that the amount of power generation is increased. In the other angular range, a braking force is applied to reduce the rotational speed of the rotor. The efficiency in power generation is increased while the rotor rotates at a high speed to compensate for a drop in power generation that takes place during the braking period.
More specifically, according to the Japanese Patent Publication No. 7-119812, the braking force is removed at first time points which occur periodically at the same period as a reference signal obtained from a crystal oscillator, etc. In addition, the braking force is re-applied at second time points, which occur alternately with the first time points with the same period as the reference signal. Accordingly, the braking force is removed and re-applied in every period of the reference signal. However, according to the Japanese Patent Publication No. 7-119812, power generation is reduced while the braking force is applied, so that there is a limit to the amount by which the braking torque can be increased while the reduction in power generation is suppressed.
In addition, according to the Japanese Patent Publication No. 7-119812, the braking force is simply applied or removed. Thus, the rotational speed of the rotor is suddenly reduced when the braking force is applied and is suddenly increased when the braking force is removed. A problem with this arrangement is that the sudden changes in the rotational speed of the rotor cause the hands connected to the rotor vibrate at a large amplitude. In addition, since the braking force is simply applied or removed, an excessive braking force may be applied even when only a small braking force is required, and the braking force may be reduced too much even when only a small reduction is required.
Especially when an excessive braking force is applied, the possibility that the rotor will stop due to a cogging torque of the rotor increases. For example, according to experiments performed by the inventors, if a generator of an electronically-controlled, mechanical timepiece is controlled to rotate at 8 Hz, the possibility that a rotor will stop due to the cogging torque increases when the rotational speed is reduced to 5 Hz by the braking force.
In contrast, when the braking force is reduced too much, there is a problem in that the rotational speed of the rotor is excessively increased.
These problems occur not only in electronically-controlled, mechanical timepieces, but also in various electronic devices such as music boxes, metronomes, etc., which include components rotated by a mechanical energy source such as a mainspring, an elastic band, etc. Thus, solving these problems would improve these timepieces and electronic devices.
OBJECTS OF THE INVENTION
An object of the present invention is to provide an electronically-controlled mechanical timepiece, an electronic device and a method for controlling such a device, which overcome these problems.
It is another object of this invention to provide such a timepiece, device and controlling method in which the braking torque can be increased while the reduction in power generation is suppressed, in which the variation in rotational speed of the rotor of the generator can be reduced, and in which the rotational speed of the rotor can be reliably controlled while preventing the rotor from stopping or rotating at an excessive speed.
SUMMARY OF THE INVENTION
According to one aspect of the present invention, an electronic device is provided. Such a device comprises a mechanical energy source; a generator configured to be driven by the mechanical energy source, to generate induced electrical power, and to provide electrical energy; and a rotation controller configured to be driven by the electrical energy, and to control the rotation period of the generator. The rotation controller includes a switch that is able to selectively connect both terminals of the generator in the form of a closed loop, a chopping signal generator configured to generate a chopping signal that is applied to the switch for brake control of the generator, and a brake controller configured to control the chopping signal generator, and thereby control a braking force applied to the generator, by switching between at least three brake control modes, including a high-power brake control mode in which an effective braking force is large, a mid-power brake control mode in which the effective braking force is less than the effective braking force of the high-power brake control mode, and a low-power brake control mode in which the effective braking force is less than the effective braking force of the mid-power brake control mode.
In the electronic device of the present invention, the generator is driven by the mechanical energy source, which may be a mainspring or equivalent component, and the rotational speed of a rotor in the generator is controlled by applying a braking force to the generator, as determined by the rotation controller.
The rotation of the generator is controlled by applying the chopping signal to the switch, that is, by turning on and off the switch, which selectively connects both terminals of a coil of the generator in the form of a closed loop. When the switch is turned on, both terminals of the generator coil are connected in the form of a closed loop so that a short brake is applied and energy is stored in the coil of the generator. When the switch is turned off and the loop is opened, the generator is activated. Because of the additional energy stored in the coil, the electromotive force (generated voltage) of the generator is increased. Since the brake control is performed based on the chopping signal, in the case in which a large braking force is applied, the reduction in power gene
Koike Kunio
Nakamura Hidenori
Shimizu Eisaku
Gabrik Michael T.
Lindinger Michael L.
Martin David
Seiko Epson Corporation
LandOfFree
Electronic device, electronically-controlled mechanical... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Electronic device, electronically-controlled mechanical..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Electronic device, electronically-controlled mechanical... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3320455