Sanyo Electric Co., Ltd.

Nippon Hoso' Kyokai

Tateo Toyama

Hiroshi Watanabe

Toshiaki Hioki

Yoshihiko Morita

Kenichi Sato

Yoichi Tsuchiya

Shuichi Ichiura

Seiji Kajiyama

Kenji Torazawa

Minoru Yasuda

Katsutoshi Hibino

Makoto Yamada

Yasuhiro Ishii

Haruo Isono

Nagatoshi Sugihara

Norihisa Takayama

Shin'ichiro Tomisawa

Yoshinobu Nishikawa

An optical disc readout apparatus is disclosured. The apparatus adjusts an optical system which leads the laser beam output from the laser diode to the objective according to the board thickness of the optical disc, and focuses the laser beam onto the information-bearing surface of the disc by the collaboration of the adjusted optical system with the objective. The adjustment can be achieved by, for example, advancing the correction lens to the optical path of the optical system or retreating the correction lens from such optical path. An another apparatus is disclosured. The another apparatus is provided with a first optical system which leads the laser beam output from the first laser diode to the common optical system and a second optical system which leads the laser beam output from the second laser diode to the common optical system. Either the first optical system or the second optical system includes a correction lens. One of the systems is selected according to a type of the loaded disc. Both the first optical system and the second optical system can focus the laser beam onto the information-bearing surface of the disc.

Optical disk readout apparatus

A disc recording/reproducing apparatus according to the present invention intermittently records and reproduces compressed digital audio data in normal recording/reproduction. In high-speed dubbing of digital audio data, two of such apparatuses are used, wherein compressed digital audio data is continuously reproduced from a disc for reproduction by the reproduction side apparatus to be directly applied to the recording side apparatus and continuously recorded on a disc for recording. Thus, the compressed high-speed dubbing of the digital audio data can be achieved without increasing a rotation speed of the disc even in high-speed dubbing.

Audio data recording/reproducing apparatus having digital high-speed

A MUSE encoder converts a HDTV signal into a MUSE signal and supplies the converted MUSE signal to a digital recording circuit 52 of a digital VTR. The supplied MUSE signal includes audio data and additional information, each being a ternary signal. A state of a ternary signal at one sampling point is discriminated by a ternary discrimination circuit 102, with the result thereof being indicated as a two-bit digital signal by a two-bit indicating circuit 103. Accordingly, the number of bits required for the audio data at one sampling point can be compressed from eight bits to two bits. In addition, by converting two successive discriminated results by the ternary discrimination circuit 102 into a binary signal by means of a ternary/binary converting circuit 104, the number of bits required at two sampling points can be reduced from 16 bits to three bits. As a result, a recording bit rate for the MUSE signal, to be digitally recorded on the magnetic tape, can be reduced.

Digital recording and reproducing apparatus for muse signal

Stereoscopic video disc record and recording and reproducing apparatus

A frequency multiplexing circuit in an optical video disc recorder frequency-multiplexes a second signal comprising a digital sound signal on the low frequency band of a first signal comprising a frequency-modulated video signal to generate a recording signal. In addition, the recording signal is applied to a limiter to be limited. In this case, a noise component produced in a band of the second signal is extracted by using a Bessel filter and a subtractor and previously subtracted from the recording signal generated by frequency multiplexing. The recording signal including a negative noise component is applied to the limiter, so that harmonic noise and linear distortion noise essentially produced in an output of the limiter can be cancelled. Furthermore, a slice level of the limiter is suitably adjusted, so that asymmetrical noise in the output of the limiter can be also eliminated.

Frequency multiplexing circuit in optical video disc recorder

Growing community of inventors

Gifu, Japan

Tateo Toyama