Matsushita Electric Works, Ltd.

Hidetoshi Amaya

Yasuo Ibuki

Toyokatsu Okamoto

Takio Maekawa

Claude Oudet

Daniel Prudham

Masao Tanahashi

Ryo Motohashi

Vibrating linear actuator and method of operating same. The actuator of the invention includes a stator, a spring vibration system having a moving portion with a magnet and further having a spring configured to support the moving portion. The actuator further includes an electromagnetic coil configured to receive an electrical current, whereupon the coil moves the moving portion against a load supplied by the spring to reciprocally move the moving portion, a frequency detector configured to detect a natural frequency of the spring vibration system, and a frequency controller configured to determine a frequency of an electrical current pulse, the pulse to be received by the coil, in accordance with a detection result of the detector.

Vibrating linear actuator and method of operating same

A control system for a linear vibration motor capable of eliminating necessity of a separate sensor of detecting the motion of the motor. The linear vibration motor includes a stator provided with a winding, and a vibrator provided with a permanent magnet. The winding is fed with a drive current to generate a magnetic field which interacts with the permanent magnet to cause the vibrator to reciprocate linearly relative to the stator for producing a vibration. The control system includes a controller which detects an ongoing amplitude, i.e., the motion represented by the displacement, speed, or acceleration of the vibrator and provides ON-periods of feeding the driving current to the winding in a varying amount based upon the ongoing amplitude detected in order to keep a vibration amplitude of the vibrator constant. The controller is characterized to provide OFF-period in which the controller instructs not to feed the drive current and in which the controller detects a voltage developed across the winding and determines the ongoing amplitude based upon the detected voltage. Thus, the winding can be best utilized commonly to drive the motor and to sense the ongoing amplitude or motion of the vibrator, thereby eliminating an additional sensor for detection of the motion of the vibrator.

Control system for a linear vibration motor

A method for driving a linear oscillating motor and a linear oscillating motor are provided. The motor includes a fixed magnetic member, a movable member having a magnet and being supported to oscillate relative to the fixed magnetic member, a detector that detects displacement of the movable member, and a control that oscillates the movable member by sending drive current to a coil of the fixed magnetic member. The method includes controlling, during a first half-period that occurs within a full amplitude period of the movable member, the drive current based upon the output of the detector. The method also includes controlling, during a second half-period that occurs within a fill amplitude period of the movable member, the drive current based upon a fixed drive current waveform.

Drive control method for linear oscillating motors and a linear oscillating 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.

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Shiga-ken, Japan

Hidetoshi Amaya