Citizen Watch Company, Ltd.

Citizen Holdings Company, Ltd.

Fumio Kanno

Koichi Sato

Fumio Nakajima

Haruhiko Higuchi

Takayasu Machida

Kiyotaka Igarashi

Kenji Yamada

Kenji Miyasaka

Kohichi Satoh

An electronic watchwhich comprises a power supplyand a watch circuit. The watch circuitcomprises an oscillator circuit, a frequency divider circuit, a drive pulse generation means, a drive motorwhich, in response to a drive pulse Pthat is output by the above-noted drive pulse generation means, drives at least one of the hour/minute, second, and functional hands including chronograph hands, a drive circuit meanswhich controls the drive of the drive motor, a drive circuit control meanswhich controls the above-noted drive circuit means, and a control condition detection meanswhich is connected to the above-noted drive circuit control meansand which detect the control condition in the drive circuit control means, the control condition detection meansbeing provided with a non-proper condition detection meanswhich senses the occurrence of a condition in which it is not possible to properly drive the above-noted drive motorunder a prescribed condition in a prescribed control mode currently being executed, and a control mode change-instructing meanswhich, in response to a detection signal of the above-noted non-proper condition detection means, issues an instruction to the drive circuit control meansto change the control mode currently being executed.

Electronic watch

Electronic watch provided with an electrical generator

An electronic watch 400 which comprises a power supply 401 and a watch circuit 402. The watch circuit 402 comprises an oscillator circuit 403, a frequency divider circuit 404, a drive pulse generation means 405, a drive motor 406 which, in response to a drive pulse P1 that is output by the above-noted drive pulse generation means 405, drives at least one of the hour/minute, second, and functional hands including chronograph hands, a drive circuit means 407 which controls the drive of the drive motor 406, a drive circuit control means 408 which controls the above-noted drive circuit means 407, and a control condition detection means 409 which is connected to the above-noted drive circuit control means 408 and which detect the control condition in the drive circuit control means 408, the control condition detection means 409 being provided with a non-proper condition detection means 410 which senses the occurrence of a condition in which it is not possible to properly drive the above-noted drive motor 406 under a prescribed condition in a prescribed control mode currently being executed, and a control mode change-instructing means 411 which, in response to a detection signal of the above-noted non-proper condition detection means 410, issues an instruction to the drive circuit control means 408 to change the control mode currently being executed.

In an electronic timepiece utilizing a stepping motor, voltage induced in the electromagnetic coil of the motor due to free oscillation of a rotor thereof is detected in a plurality of successive detection periods after application of a driving force to the motor is completed, and it is determined on the basis of such induced voltage for the respective detection periods whether the rotor failed to step or not. If the stepping failure is determined in at least one detection period, a compensation pulse is fed to the stepping motor to compensate for the stepping failure of the rotor and thereafter driving energy supplied to the electromagnetic coil of the motor is increased.

Timepiece stepping motor drive circuit with stepping failure compensation

In an electronic timepiece having two stepping motors, one for driving at least a second-hand and the other for driving at least an hour-hand, rotation or non-rotation of the rotor of said other stepping rotor is detected and when non-rotation is detected, failure of stepping of said other stepping motor is determined and said one stepping motor is controlled to be actuated in a warning mode which is different from a normal mode to give warning of the failure of stepping of said other stepping motor.

Electronic timepiece

An electronic timepiece havig a stepping motor driving time indicating hands is provided with a system whereby the stepping motor is selectively driven at one of three different drive power levels, in accordance with the load currently being applied to the motor. Detection of the load level is performed by momentarily sampling a voltage induced in the motor drive coil during a short time interval following a drive pulse. The system provides rapid response to changes in load level, highly stable control, and excellent tolerance to variations in characteristics of different stepping motors and circuit components.

In an electronic timepiece having a stepping motor which drives time indicating means, a system is provided for detecting an increase in the load torque on the stepping motor above a predetermined level. When such an increase is detected, the conditions for detection of the load on the stepping motor are changed, and thereafter drive pulses of increased power are applied to the stepping motor. When the increased load is removed, this is detected under the new set of detection conditions, and a return to the original detection conditions is executed, with the drive pulse power being returned to the original level. Stability of control is thereby provided, together with immediate response to increased load on the stepping motor.

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Tokyo, Japan

Fumio Kanno