Matsushita Electric Works, Ltd.

Takio Maekawa

Yasuo Ibuki

Toyokatsu Okamoto

Hidetoshi Amaya

Claude Oudet

Hideki Tamura

Hideaki Abe

Daniel Prudham

Masao Tanahashi

Ryo Motohashi

Satoru Inakagata

Atsushi Takahashi

Shosuke Akisada

Mikihiro Yamasita

A controlling apparatus for controlling a linear oscillation motor includes a sensor and a controller. The motor has a movable element and a stator one of which includes an electromagnet with a winding. The sensor is configured to detect movement of the movable element. The controller is configured to intermittently supply electric power to the winding of the electromagnet to move the movable element reciprocally and linearly. The controller is configured to begin each intermittent supply of electric power to the winding at a timing before a dead center of the movable element based on an output of the sensor.

Controlling apparatus for linear oscillation motor and method for controlling linear oscillation motor

A linear vibration motor which includes a vibration system, an electromagnetic driver, a detection system, and a control system. The vibration system includes a driven member or reciprocator which is mounted to a magnetic member for reciprocating movement. The amplitude of the reciprocating movement varies as an inverse function of load on the motor. The electromagnetic driver includes a coil and drives the vibration system by applying an electromagnetic force to the magnetic member, the electromagnetic force being produced by a driving current flowing through the coil. The detection system detects at least one characteristic of the vibration system that is related to a characteristic frequency of the vibration system, and produces a feedback signal indicative of a value of the at least one characteristic. The control system is responsive to the feedback signal, during a primary mode of operation, to controllably vary the driving current flowing through the coil in such a manner as to drive the vibration system in resonance with the characteristic frequency, and determines the existence of a condition that renders the detection system non-functional, and drives the vibration system at a prescribed frequency when it is determined that the condition exists, during a back-up mode of operation.

Linear vibration motor and method for controlling vibration thereof

A linear oscillating motor capable of assuring a consistent and effective feedback control of keeping a constant oscillation amplitude with varying load conditions. The linear oscillating motor comprises an oscillator carrying a permanent magnet, and a stator with an electromagnet. The electromagnet is supplied with an electric power to develop an electromagnetic drive force of moving the oscillator in a linear direction relative to the stator. A spring is provided to apply a restoring force to the oscillator for providing a linear oscillating motion to the oscillator. A photo-sensor monitors the linear motion of the oscillator and outputs a signal to a reverse-point detector which determines right and left reverse points of the oscillator. A controller applies the electric power to the electromagnet at the drive points respectively defined subsequent in time to the reverse points and in a varying amount for keeping a constant oscillation amplitude of the oscillator. The photo-sensor outputs a train of pulses appearing each time the oscillator passes its oscillation center. The reverse-point detector determines the reverse points based upon a time period between the two preceding pulses. Since the photo-sensor can monitor an oscillation cycle of the oscillator without being affected by the magnetic field developed by the electromagnet for driving the oscillator, it provides a reliable basis for accurately determining the reverse points and therefore the drive points. Accordingly, the driving force can be applied at an optimum timing to make the feedback control accurately and reliably.

Linear oscillating motor

An inverter power supply having a DC source, a transformer having a primary winding, a secondary winding, and a feedback winding, an L-C resonant circuit of a capacitor and the primary winding, and a self-excited oscillator. The oscillator includes an L-C resonant circuit and an FET connected in series with the primary winding across the DC source to generate a high frequency voltage across the primary winding, a feedback voltage across the feedback winding and a resulting output AC voltage across the secondary winding. A biasing capacitor is connected in parallel with a series combination of the L-C resonant circuit and the FET across the DC source to be charged thereby. The biasing capacitor is also connected in series with the feedback winding to provide an offset voltage which is additive to the feedback winding to give a bias voltage applied to a gate of the FET so as to alternately turn on and off the FET for driving the self-excited oscillator. A current sensor is provided to sense a current flowing through FET and gives a first level signal indicative of the sensed current being fed to the resonant circuit. Extending across the biasing capacitor is a single discharge path which does not go through the FET. A switching transistor is inserted in the single discharge path and is caused to turn on, upon the first level signal exceeding a threshold level, to discharge the biasing capacitor to a level for maintaining the offset voltage at a constant level during continued oscillation of the L-C resonant circuit.

Inverter power supply with single discharge path

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Hikone, Japan

Takio Maekawa