Matsushita Electric Industrial Co., Ltd.

Yoshiteru Hosokawa

Makoto Gotou

Takafumi Asada

Yoshiaki Igarashi

Minoru Koda

Tadao Shioyama

Cyuryo Yoshida

Takafumi Akeda

Rotary head device with fluid bearing

A brushless DC motor, in which power supplied to polyphase stator coils is controlled by drive transistors, has a DC-DC switching converter for producing an output voltage according to an on-time ratio of the switching semiconductor, a voltage controller for detecting a voltage drops across the drive transistors and for controlling the on-time ratio of the switching semiconductor so that the voltage drops across the drive transistors become a predetermined small value, a temperature detector for detecting a temperature of the drive transistors, and a current reviser for reducing the output currents of the drive transistors in each activated period so that the currents of the drive transistors are controlled in response to a command signal and an output of the temperature detector.

Brushless DC motor

In a magnetic recording and reproducing device for recording a video signal intermittently by a rotary magnetic head, a skewing of the reproduced image can be prevented by controlling the rotation phase of the rotary magnetic head so as to record the horizontal synchronizing signals of the adjacent two tracks so that the phases are conincident, and also a skewing of a reproduced still image can be prevented by controlling the angular velocity of the rotary magnetic head so as to record an integral number of the horizontal synchronizing signals on a scanning trace of the head when the magnetic tape is stopped.

Magnetic recording device for synchronizing headwheel movement

Growing community of inventors

Hirakata, Japan

Yoshiteru Hosokawa