Sanyo Electric Co., Ltd.

Hideki Osawa

Tsuyoshi Yamamoto

Koji Tsukagoshi

Yasushi Hanamoto

Hiroyuki Mutou

Hitoshi Ogura

Yasuki Mori

Syuzi Inoue

Nobumasa Nakagawa

In an optical disk recording and reproducing device which uses an optical disk having at least a first recording layer and a second recording layer, a thickness of a spacer section between the first recording layer and the second recording layer is measured, an amount of defocus with respect to the second recording layer is set based on the measured spacer thickness, and a focus servo operation is performed for focusing the laser light irradiated from an optical pickup device on the second recording layer.

Method of controlling focus of optical disk recording and reproducing device

A DC voltage value is obtained at least at an inside position, an intermediate position, and an outside position on a disc () from a drive signal that is supplied to a focusing coil () built into an optical pickup (). From the DC voltage values is obtained a relationship of a position between the respective positions and the DC voltage value, and this relationship is stored into a memory circuit (). Then, during recording or playback, the DC voltage value that is calculated on the basis of the recording or playback position of the signal at that time and the AC signal included in the drive signal that is supplied to the focusing coil () are added to create a signal to be supplied to a tilt adjustment coil ().

Tilt control for optical disc recording and playback apparatus

A signal recording apparatus comprising the operation portion to be manipulated when it is found necessary to record a signal on a recording medium while the signal is being produced, a signal conversion circuit for converting the signal to a digital signal, a memory circuit of specified capacity for temporarily storing the digital signal from the conversion circuit and thereafter feeding the signal to a signal recording head, and a main control circuit for controlling the memory circuit for storing the signal therein and reading out the signal therefrom. In response to a recording start instruction given by the operation portion, a system for driving the recording medium is initiated into operation, and at the same time, the signal is read out from the memory circuit retroactively since a predetermined time interval prior to the manipulation of the operation portion and is recorded on the medium.

Signal recording apparatus

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Fukaya, Japan

Hideki Osawa