Abstract: An optical recording and reproducing system having an accurate high-speed optical head positioning apparatus. In one embodiment, a positive acceleration is applied to the optical head until the optical head has moved half the distance to a target track. Thereafter, a negative acceleration is applied to the optical head to decelerate the optical head until the optical head arrives at the target track. Feedback control is not used while the optical head is moving, thus eliminating a delay in response time due to a limited servo band upon the transition from the positive acceleration to the negative acceleration.

Abstract: An error detection and/or correction is achieved in the horizontal direction in a block and then an error state is determined by use of an error correction in the vertical direction; furthermore, the correcting system is changed over according to the result of the determination.

Abstract: This invention relates to a phase coincidence detector for examining whether or not two input digital signals are coincident by utilizing a delay signal and an advance signal of a digital phase comparator which examines the phase difference between the two input digital signals and outputs the delay signal representing the delay of one of the input signals to the other and the advance signal representing the advance of one of the input signals to the other. Particularly, the output signals of the phase comparator, that is, the delay signal and the advance signal, are periodic pulse signals, and residual pulses having a small pulse width occur periodically even at the time of coincidence.

Abstract: A light emitted from a laser diode is reflected by a video disc which is rotated by a spindle motor. The reflected light is modulated by video information recorded on the video disc and converted to an electrical signal by a photodiode array. A signal generated by a trapezoidal generator is sampled with a horizontal synchronizing signal separated from the video information signal. The sampled signal is supplied to the spindle motor for correcting a time base error. A zero crossing point of the trapezoidal waveform is detected and is utilized for controlling the start of a rise portion of the trapezoidal waveform for compensating a DC offset. The trapezoidal waveform is controlled so as to vary an average power supplied to the spindle motor in accordance with a detected rotational speed difference so as to compensate a rotational speed of the spindle motor.

Abstract: A magnetostatic wave tunable resonator which has fine stripe electrodes and bonding electrode films formed on the surface of a YIG thin film supported by a GGG substrate. The stripe electrodes, bonding electrode films and edges of the YIG film are formed by a chemical etching method based on photolithography. The resonator so formed has suppressed spurious resonance of high order modes and enables the use of a magnet of greatly reduced size.

Abstract: In an apparatus for reproducing information recorded on a disk having a tracking servo device for an actuator which directs a read beam to a track of the disk, a first power product is applied to the actuator upon turn-off of the tracking servo system, a velocity of the actuator is detected based on an error signal from the tracking servo device, the velocity of the actuator detected immediately after the start of movement of the actuator is stored, on the basis of the detected result, the subsequent velocity of the actuator is sequentially compared with the initial velocity and the velocity is controlled at a constant value until the actuator reaches a predetermined track.

Abstract: A rotary cylinder device for helical scan type magnetic recording/reproducing apparatus including a rotary cylinder having an axis of rotation arranged in opposition a stationary cylinder in the direction of the axis of rotation with a small gap therebetween. The rotary cylinder has an end surface facing the stationary cylinder and an outer peripheral surface, recesses formed in the end surface and opening in the outer peripheral surface so as to extend therefrom radially inwardly over a small distance. Each of the recesses has a leading end wall and a trailing end wall, as viewed in the direction of rotation of the rotary cylinder. Magnetic heads are fixed to the rotary cylinder and are positioned in the recesses and have outer extremities projecting beyond the outer peripheral surface of the rotary cylinder.