Olympus Optical Company, Ltd.

Tsutomu Shibata

Kenji Kimura

Ken Satoh

Toshikazu Kato

Sinichi Saitou

Ken Ohshima

Seizo Watanabe

A light beam emitted from a laser light source is made incident upon a video disc by means of an objective lens and a light flux reflected by the disc is made incident upon a light detector arranged in a far field of an information track of the disc. The light detector includes four light receiving regions divided in a track direction and a direction perpendicular to the track direction. A first sum of output signals from diagonally aligned two light receiving regions and a second sum of the remaining two light receiving regions are derived and then a sum signal and a difference signal of the first and second sums are formed. The difference signals are sampled by sampling pulses generated at positive going and/or negative going zero cross points of the sum signal to generate sampled values. A tracking error signal is obtained from sampled values.

Signal detection system for use in an optically reproducing apparatus

This invention is for a tape cassette having window for insertion of a magnetic head and a pinch roller formed extending from a peripheral wall of the housing of the tape cassette to one of the holding plates which holds a pair of reel hubs in place. The device according to this invention has a shutter member, and a resilient metal wire housed in the housing. The shutter member has projections which are to be engaged with an engaging member provided on a tape cassette holder member of the magnetic tape transport apparatus. The metal wire urges the shutter member to close a portion of the window formed in the holding plate. When the cassette is loaded into the loading member, the projections engage with the engaging member and the shutter member releases the closing state of the holding plate forming portion of the window against an urging force of the wire. When the cassette is removed from the loading member, the shutter member closes the holding plate forming portion to prevent the tape from being damaged by an external force.

Magnetic record tape protective device for a tape cassette

First and second capstans are rotated at respective speeds by first and second motors. The speeds of revolution of the first and second motors are detected as detection signals, and the revolution speed of at least one of the first and second motors is controlled in accordance with a difference between the detection signals. An offset voltage is added to one of the detection signals corresponding to the revolution speeds of the first and second motors for the control of tape tension.

Double-capstan tape driving device

A tape cassette according to this invention comprises at least three guide rollers disposed inside the housing of the tape cassette. The at least three guide rollers define a position of the magnetic recording tape of the tape cassette relative to the housing across the thickness thereof while the tape is travelling from one of two reel hubs held by the housing along a path extending adjacent a front wall of the housing, the front wall having openings for the insertion of a magnetic head and a pinch roller.

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Hachioji, Japan

Tsutomu Shibata