Citizen Watch Company, Ltd.

Kenji Yamada

Fumio Nakajima

Takayasu Machida

Yasushi Nomura

Minoru Watanabe

Fumio Kanno

In a circuit for driving a pulse motor of an electronic timepiece, the initial part or entirety of each drive pulse is modulated to form a group of high frequency pulses thereby reducing an initial surge of current while rotor of motor is still stationary. Modulation can be controlled according to load placed on motor to provide increased drive energy for heavy loading.

Drive system for pulse motor

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.

Drive control system for stepping motor

An electronic timepiece having a reversible stepping motor to actuate time-indicating hands to provide a time display, which comprises a driver circuit to produce driving current pulses composed of compound pulses appearing each time unit. A rotor of the stepping motor rotates a plurality of steps during each time unit to cause one of the time-indicating hands to advance through unequal intervals to provide a modulated display.

Electronic timepiece

An electro-mechanical transducer driver circuit for an electronic timepiece characterized in that the pulse width of a driving pulse which drives an electro-mechanical transducer is controlled in a step-wise manner by the induced voltage of a driving coil.

Driver circuit for electro-mechanical transducer

An electronic timepiece includes a reversible stepping motor to drive rotatable hands to provide a time display. In a first preferred embodiment, the electronic timepiece includes a circuit means to generate alternating current pulses having an increased pulse width or an increased amplitude to drive the stepping motor with an increased driving current during high speed time correction when a manually operable external control member is actuated during time correction. In a second preferred embodiment, the electronic timepiece comprises a clockwise correction switch, a counter-clockwise correction switch and circuit means for generating first and second alternating current pulses of first and second pulse widths at a predetermined frequency higher than normal driving pulses to drive a stepping motor in clockwise and counter-clockwise directions, respectively, to perform clockwise and counter-clockwise corrections when the clockwise and counter-clockwise correction switches are actuated during time corrections, respectively. The pulse width of the second alternating current pulses is selected to be smaller than that of the normal driving pulses.

A stepping motor for use in an electronic timepiece in which a rotor is stable on an axis of static equilibrium at an angle from 0.degree. to 30.degree. with respect to a center line of the air gaps between stator pole pieces. The relationship between the stator pole pieces and the rotor is such that the phase difference between driving torque and attraction force applied to the rotor ranges from 60.degree. to 90.degree. by an electrical angle in a normal rotation of the rotor and ranges from 90.degree. to 120.degree. in a reverse rotation of the rotor.

Stepping motor for electronic timepiece

A stepping motor for use in an electronic timepiece which has a permanent magnet rotor and a stator provided with a driving coil. The stator is comprised of stator pole pieces each having assymetric portions which provide primary and secondary magnetic paths, respectively, whereby two static equilibrium positions are provided. The rotor may be stable at either one of these static equilibrium positions by controlling the supply of two-phase pulses to the driving coil so that the rotor may be rotated in normal or reverse direction. Su

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Koganei, Japan

Kenji Yamada