Abstract: A rotary head device with a fluid bearing including an upper cylinder and lower cylinder, a sleeve provided on the lower cylinder, a rotary shaft rotatably inserted in the sleeve, and pairs of cylindrical rotary transformers are mounted on the upper and lower cylinders, with two spaced apart herringbone patterns of grooves (26A and 26B) formed either on the rotary shaft or on the inside surface of the sleeve, the length of the herringbone pattern of grooves being larger on the upper cylinder end of the shaft or sleeve, and smaller on a motor end of the shaft or sleeve.

Abstract: 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.

Abstract: 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.