Kabushiki Kaisha Daini Seikosha

Seiko Instruments Inc

Seiko Instruments & Electronics Ltd.

Shuji Otawa

Masaharu Shida

Makoto Ueda

Masaaki Mandai

Katsuhiko Sato

Akira Torisawa

Takashi Sato

Kenichi Ono

Masao Kasuga

Fujio Ozawa

An ultrasonic motor capable of being accurately step-driven comprises a vibrating member piezoelectrically vibrated for driving and halting a movable member. A driving wave is generated for vibrating the vibrating member to drive the movable member, and a halting wave is generated for vibrating the vibrating member to halt the movable member. The driving wave can be either a travelling wave or a standing wave, and the halting wave is a standing wave. The movable member is divided into a plurality of portions, and when the vibrating member is driven by the halting wave, the portions of the movable member become centered at respective nodal portions of the standing halting wave, causing the movable member to stop rotating so that the ultrasonic motor can be accurately step-driven.

Ultrasonic motor

An electronic timepiece having a stepping motor includes a power source, an oscillating circuit, a dividing circuit connected to the oscillating circuit, and a wave shaping circuit receptive of a plurality of output signals produced from the dividing circuit to produce a plurality of controlling signals. A controlling circuit receives the controlling signals and controls a driving circuit. The power source is connected to a detecting voltage circuit by which the variation of the supply voltage of the power source is detected, and a normal waveform or an intermittent waveform is selectively applied to the stepping motor according to the variation of the supply voltage. As a result, the power consumption of the steppng motor is controlled at a constant level, even if the supply voltage of the power source is higher than the optimum voltage of the stepping motor and even if the supply voltage varies.

Electronic timepiece

An analogue alarm electronic timepiece has electronic circuitry for controlling the drive of the time-indicating hands by a reversible stepping motor to selectively position the hands at desired alarm time and display time settings. Externally operable switches control the operation of the electronic circuitry and enable re-positioning of the hands by the motor to the previously set alarm time so that the user of the timepiece may confirm the alarm time setting. The electronic circuit includes a first settable memory means for storing the time difference between the alarm time and the present time, and a second settable memory means for storing the time difference between the present time and the display time. First means are provided for detecting coincidences between the alarm time and the present time. Second means are provided for detecting coincidence between the present time and the display time.

Analogue alarm electronic timepiece

An electronic timepiece has a stepping motor comprised of a stator, rotor and coil, and circuitry for producing and applying driving pulses to the coil to effect stepwise rotation of the rotor. The presence of an external alternating magnetic field is detected by switching the coil from an open-circuit condition to a low impedance loop comprised of the coil and a low impedance element. The rotation of the rotor is detected by alternately switching the coil between the low impedance loop and a high impedance loop comprised of the coil and a high impedance element. Control circuitry controls the switching operations to ensure that the magnetic field detection and the rotor rotation detection are carried out at different times.

Detection device of electronic timepiece

An electronic timepiece has a stepping motor comprised of a stator, rotor and driving coil. A wave shaping circuit produces normal driving pulses and correction driving pulses having a longer pulse width than the normal driving pulses. A rotor rotation detection device detects rotation and non-rotation of the rotor after normal driving pulses are applied to the driving coil and in response to detection of a non-rotation condition, a correction driving pulse is applied to the driving coil. A magnetic field detection device detects the presence and absence of an external alternating magnetic field and in response to detection of a magnetic field, a driving pulse of longer pulse width than the correction driving pulses is applied to the driving coil to effect rotor rotation. The magnetic field detection device operates before the normal driving pulses are applied to the driving coil so that in the event of detection of a magnetic field, a driving pulse of sufficiently long pulse width will be applied to the driving coil to effect rotor rotation. In response to detection of an external alternating magnetic field by the magnetic field detection device, operation of the rotor rotation detection device is inhibited thereby conserving power and preventing mis-operation of the stepping motor.

An electronic timepiece includes a stepping motor having a stator, a drive coil and a rotor which is driven in one of at least two different states. The state of the driving motor is changed in response to a change in the load of the motor or in response to the locating of the motor in an external magnetic field.

An electronic timepiece of the type having a frequency dividing circuit, and a drive circuit for driving a motor having a rotor, a stator and a driving coil, is provided with a magnetic field detection device comprised of a low impedance closed loop including a low resistance element and the driving coil and a high impedance closed loop including a high resistance element and the driving coil. The driving coil develops an induced voltage when placed in an external alternating magnetic field and also functions to drive the rotor. The strength of the alternating magnetic field is measured by the voltage level developed across the high resistance element and the measuring sensitivity is improved by alternately switching between the low impedance closed loop and the high impedance closed loop. In response to the detection output of the magnetic field detection device, the effective power applied to the driving coil is increased so that the motor performance is not adversely affected by the external alternating magnetic field.

Growing community of inventors

Tokyo, Japan

Shuji Otawa