Citizen Watch Company, Ltd.

Union Kogaku Kabushiki Kaisha

Fumio Nakajima

Takayasu Machida

Kenji Yamada

Akira Nikaido

Yasushi Nomura

Takashi Toida

Fumio Kanno

Mitsuo Onda

Yasuhisa Hirosawa

Minoru Watanabe

Hidemasa Yoshida

Hirohiko Yoshida

Tadami Taoka

Kimio Maru

Hisashki Kawamura

Kazutoshi Arita

Yutaka Hirano

A tuning-fork sensor is formed with a piezoelectric single crystal and its drive arm,is self-excitedly vibrated by an oscillation circuit at a resonance frequency f0 in a predetermined direction. A sensor arm,also vibrates in the same direction in synchronization with the drive arm, and forcibly vibrates in the direction orthogonal to the direction of the vibration at the same frequency as f0 by a Coriolis force induced by the rotation. First sensor electrodes of the sensor arm are connected to a ground wire, a positive-input terminal of an operational amplifier forming a sensor circuit is connected to the ground wire, second sensor electrodes and a negative-input terminal are connected to each other, and the negative-input terminal and an output terminal are connected to each other through a feedback resistor

Angular velocity sensing device

An angular velocity sensor including a tuning-fork sensor element made of a material exhibiting piezoelectricity to have two arms formed integrally on a base and electrodes provided on surfaces of the arms. The free end of each arm is formed with an extension projecting outward in the direction of arm vibration. The surfaces of the arms lying in the direction of vibration and the surfaces thereof lying orthogonal to thee surfaces are each provided with a single electrode. When the angular velocity sensor experiences an angular velocity owing to rotation about an axis orthogonal to the plane of the tuning fork, Coriolis forces act on the arms in the same direction as or the opposite direction from that of the vibration at that instant, thereby producing a bending moment. The direction and magnitude of the angular velocity can be determined by detecting the voltages produced by the bending moment.

Angular velocity sensor and angular velocity sensing system

The angular velocity sensing device is structured in such a manner that a first vibration element 1 having piezoelectric elements or electrodes (two or more) for generating oscillation and a second vibration element 2 having piezoelectric elements or electrodes (two or more) for sensing angular velocity are connected through first connection portions (two or more) on nodes of vibration (two or more) of the first vibration element 1, and the second vibration element 2 and a supporting portion are connected with each other through second connection portions (two or more). These first, second vibration elements, the supporting portion, and the first, second connection portions have a plane structure with almost uniform thickness, and both of the first vibration element and the second vibration element are made to have symmetric shapes with respect to the common center point P.

Electronic watch

An angular velocity sensor including a tuning-fork sensor element made of a material exhibiting piezoelectricity to have two arms formed integrally on a base and electrodes provided on surfaces of the arms. The free end of each arm is formed with an extension projecting outward in the direction of arm vibration. The surfaces of the arms lying in the direction of vibration and the surfaces thereof lying orthogonal to these surfaces are each provided with a single electrode. When the angular velocity sensor experiences an angular velocity owing to rotation about an axis orthogonal to the plane of the tuning fork, Coriolis forces act on the arms in the same direction as or the opposite direction from that of the vibration at that instant, thereby producing a bending moment. The direction and magnitude of the angular velocity can be determined by detecting the voltages produced by the bending moment.

The electronic watch according to the invention comprises an energy source 1 (power supply), storage circuit 3, clock output unit 4, constant voltage circuit 5, voltage detection circuit 6, switching circuit 8, and control unit. The energy source 1 transforms external energy into electric energy and supplies a power supply voltage. The storage circuits 3 stores the power supply voltage or a booster voltage of the power supply voltage and thereby supplies a storage voltage. The clock output unit has a watch system and a condenser of a small capacitance, receives any of the power supply voltage or the booster voltage, and the storage voltage, and supplies a plurality of logic signals. The constant voltage circuit 5 generates a reference voltage from the clock voltage. The voltage detection circuit 6 compares the power supply voltage or booster voltage, storage voltage, and clock voltage selectively with a voltage set on the basis of the reference voltage and supplies a voltage detection signal. The switch circuit 8 is provided with a plurality of switches for controlling charging times of the storage circuit and the clock output unit. The control unit controls the switching circuit 8 by a plurality of pulse width variable switch control signals corresponding to a plurality of the logic signals and the voltage detection signal.

Electronic watch and method of charging the same

An electronic watch comprises a power supply 1 for generating electric energy by using external energy, a booster portion 2 having at least two booster circuits for sequentially repeating charging by the power supply 1 and boosting and discharging a charged voltage, a storage portion 3 for storing a charge discharged by the booster portion 2, a clock output portion 6 connected to an output terminal of the storage portion 3 and also connected to the power supply 1 by way of a reverse-blocking diode 8 for blocking the stored voltage from reversely flowing to the power supply 1, and a first voltage comparator portion 4 serving as a control portion, wherein the first voltage comparator portion 4 outputs a control signal for switching between charging and discharging of each booster circuit constituting the booster portion 2. Accordingly, effective charging can be made without being influenced by an internal resistance of the power supply 1, thereby reducing the variation of the stored voltage.

Electronic watch and method of driving the same

Super-miniature motor

An angular velocity detector circuit composed of: an oscillator circuit including an inverting amplifier connected between a driving electrode of a quartz crystal and an electrode for detecting an electric field generated in the quartz crystal by a Corioli's force when the quartz crystal is rotated; a differential amplifier circuit connected at its input terminals to the detecting electrode of the quartz crystal; a detector circuit which receives the output from the differential amplifier circuit and using the output from the oscillator circuit as detection signals; and an output amplifier circuit which receives the output from the detector circuit.

Quartz crystal oscillator angular velocity detector circuits

A carriage device used for moving and positioning a magnetic head opposite prescribed tracks of a magnetic disk has the magnetic head mounted on a carriage which has linear motor mechanisms built integrally therein. The linear motor mechanisms incorporate coils secured to part of the carriage and permanent magnets secured aorund the coils. Guide rails serving to support the carriage within the range of the sliding motion of the coils are made of a magnetic substance.

Carriage device for moving and positioning magnetic head

The present invention provides a micro stepping motor for more accurately stepping and positioning a magnetic head in a magnetic disc system. The stepping motor has a permanent magnet type rotor and a stator encircling the rotor, the rotor having a plurality of pole teeth formed therein with a fine pitch and the stator also having a plurality of pole teeth formed therein with a fine pitch and disposed opposed to the pole teeth in the rotor, the stator pole teeth being divided into at least one pair of pole tooth groups which are out of phase relative to each other by an electrical angle of 180 degrees. A single common stator coil is provided to the pair of stator pole tooth groups. Thus, the stepping pitch of the rotor is determined by the pitch in the pole tooth groups, whereby the rotor can steppingly be driven with higher density even by the reduced number of stator coils. In addition, plural pairs of pole tooth groups can be formed such that at least two pairs of pole tooth groups and the corresponding two stator coils will be provided to determine the stepping angle of the rotor optionally under the multi-excitation.

Micro stepping motor

A motor driving circuit comprising a pulse generating circuit for generating plural types of pulse trains, a modulation pulse generating circuit connected to the pulse generating circuit, a semiconductor driving circuit connected to an output of the modulation pulse generating circuit for providing operating power to a motor winding, a detecting circuit connected to the driving circuit for detecting a voltage induced in the motor winding, and a counting circuit connected to the detecting circuit. The detecting circuit has means for setting reference levels, detects the voltage induced in the motor winding in accordance with the reference levels during the time the semiconductor driving circuit is non-conducting, and sends control signals for regulating a next produced modulation pulse width to the counting circuit, and the modulation pulse generating circuit shapes the modulation pulse from the plural types of pulse trains of the pulse generating circuit in accordance with outputs of the counting circuit so as to drive the motor uniformly.

Motor driving circuits

An electronic timepiece comprising a step motor composed of an electromagnetic coil excited by two phase alternating driving signals, characterized by comprising means for changing over the electromagnetic coil from a closed circuit condition to an open circuit condition and vice versa, means for detecting shocks, means for discriminating the shock direction, and means for controlling the driving signal.

Electronic timepiece

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

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.

Growing community of inventors

Tokyo, Japan

Fumio Nakajima