Victor Company of Japan, Limited

Yoshihiko Honjo

Hisao Kinjo

Ichiro Ueno

Ryozo Abe

Kenji Yoshihara

Masaki Sakurai

Yoshiyo Wada

Seisuke Hiraguri

Kazuo Tatsuguchi

Juichi Shikunami

Junji Kuroda

Kazuhiro Hosono

Hisayoshi Yamada

A rotary recording medium recorded with an information signal including a video signal along a spiral track thereon, and from which the recorded information signal is reproduced by a reproducing apparatus in which a reproducing element scans over the spiral track, is further recorded with a stop signal on a track turn recorded with an information signal which is to be reproduced repeatedly for a predetermined time period so that the reproducing element repetitively reproduces the track turn for the predetermined time period. The reproducing apparatus comprises a stop signal detection circuit for detecting the stop signal from a signal reproduced by the reproducing element, and a circuit responsive to the stop signal detected by the stop signal detection circuit, for causing repetitive reproduction of a predetermined track turn recorded with the stop signal. The still picture reproduction is performed by repetitively reproducing the information signal recorded on a track turn recorded with the stop signal.

Rotary recording medium and reproducing apparatus therefor

An optical apparatus reproduces an information signal recorded as pits along track turns of a rotating recording medium. At least one kind of reference signal is recorded along and overlapping the lateral edges of the adjacent track turns of the information signal. A light source projects a first light beam onto the surface of the recording medium to simultaneously reproduce the information and reference signals. A detector responds to reflections of the projected light which includes and reproduces the information signal and the reference signal. The optical system is controlled so that the center of the light beam coincides with the centerline of the track. A circuit separates the reference signal from the total reproduced signal and produces a tracking control signal in response thereto. The optical system also projects a second light beam onto the recording medium and its reflected component is used for focus control. The depth of focus of the objective lens is substantially equal to or less than two times the pit depth, so that the focussing point of the reproduction light beam coincides with the upper surface of the rotating recording medium or the bottom surface of the pits. Thereby resulting in fine reproduction without introducing second-order harmonic distortion.

Apparatus for optically reproducing signals recorded on a rotating

The invention provides a system for optically recording information on a recording medium. A light source emits a laser light beam and an optical system, including a lens, focuses the laser beam spot on the recording medium. The light intensity of the laser beam is modulated responsive to an information signal. The light modulator is in a path between the light source and the optical system. A noise component is detected in the laser light beam passing through the light path and removed therefrom. The optical system records the information on the recording medium by the laser light beam, in which the noise component has been removed, and on which the information has been applied by the light modulator.

Signal noise filtration for laser beam recording system

The invention relates to a system for detecting the height fluctuations of a surface on a recording medium in an optical recording or reproducing apparatus. A light source emits a main light beam for recording or reproducing. An optical system, including an objective lens, focuses the main light beam into a spot on the surface. A first reflecting mirror introduces a sublight beam into the peripheral part of the main light beam. The sub-light beam advances in a forward path through the objective lens to be projected onto the recording surface and reflected thereby. The sub-beam returns again through the objective lens along the peripheral part of the main light beam, but on the opposite side from said forward path. A second reflecting mirror extracts the sub-light beam in the return path out of the light to operate a detector which detects fluctuations in the distance between the objective lens and the recording surface and to produce control signals maintaining a constant distance between the objective lens and recording surface.

System for detecting height fluctuations of a surface on a recording

A switching circuit connects a magnetic head in a magnetic recording and reproducing apparatus. The magnetic head is used for recording and reproducing signals onto and from a magnetic recording medium. The switching circuit comprises a first electronic switch connected between ground, the output side of a recording amplifier, and one terminal of the magnetic head. The switch becomes nonconductive during the recording mode and becomes conductive during the reproducing mode. A second electronic switch circuit is connected substantially between ground, the other terminal of the magnetic head, and the input side of a reproducing amplifier. The second switch becomes conductive during recording and nonconductive during the reproducing mode.

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Ayase, Japan

Yoshihiko Honjo