Pioneer Electronic Corporation

Shigeru Kato

Hideki Hatano

Norikiyo Tajiri

Sakashi Otaki

A noise reduction system which is unaffected by bandwidth limitations of the transmission system with which the noise reduction system is employed. The noise reduction system is of a type including a compressor, the transmission system, which receives a compressed signal from the compressor, and an expander for expanding a signal outputted by the transmission system. In accordance with the invention, a low-pass filter having a pass band corresponding to the transmission band of the transmission system is provided in the stage prior to the compressor. In another embodiment, a low-pass filter is provided in a stage prior to a level detector within the compressor.

Noise reduction compression system controlled by compressed output

Disclosed is a system for recording and playing back information utilizing a magneto-optical disc memory having a vertical magnetization film on and from which the information is recorded and read out by an optical means. In order to simplify the construction of the system, an optical system including an objective lens and a tracking mirror is used both as a part of an optical path of a recording light beam and a part of an optical path of a readout light beam. The wavelengths of the recording light beam and the readout light beam are selected to be different so that the light beams are easily discriminated in the optical system.

System for recording and playing back information with magneto-optical

Disclosed is a method and system for recording and playing back information utilizing a recording medium having a vertical magnetization film on and from which the information is recorded and read out by an optical means, characterized by changing the direction of the magnetic field applied on the recording medium during the application of a recording light beam so as to maintain the recording track of portions of the recording medium on which the previously recorded information is erased by the application of the recording light beam during editing operations.

Method and system for optically recording and playing back information

Disclosed is an information recording system having a recording light beam passing through a focus lens, and a focus servo mechanism for adjusting the position of the focus lens, characterized by the provision of a bias beam of a weak intensity for producing a continuous control signal for the focus servo mechanism.

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Tokorozawa, Japan

Shigeru Kato