Matsushita Electric Industrial Co., Ltd.

Kiyoyuki Suenaga

Shingo Sagata

Makoto Taromaru

Koji Muraoka

Hiroyuki Gondo

Kouji Muraoka

Hiroyuki Gondou

Tomomichi Tamura

An apparatus for reproducing data from the optical disk at a constant linear velocity includes a specified rotation speed detection module which decides whether or not the optical disk is rotating at a specified rotation speed. A linear velocity calculation module arithmetically determines the linear velocity by measuring a time taken for a complete rotation of the optical disk at a start position of a data area on the optical disk when the optical disk is detected as rotating at a specified rotation speed.

Optical disk drive apparatus and linear velocity calculating method

A servo control system for controlling position of a readout head such as a magnetic or optical head which records, reproduces or erases information on or from a magnetic or magneto-optical disk. This servo control system includes an actuator for moving the head toward a required position on the disk, a position detecting circuit for detecting a position of the head relative to the disk, and a signal processing circuit for processing an output signal from the position detecting circuit to provide a control signal to the actuator. When a value of the signal from the position detecting circuit falls within a preselected range, a controller deactivates a servo control operation of the signal processing circuit and modifies controlled parameters used in the servo control operation in response to a disturbance such as vibration of the system.

Servo control system for head recording and/or reproducing information

An optical disk apparatus equipped with an objective lens for converging light from a light source onto a track formed on an optical disk, the objective lens being arranged to be movable and an error detecting section for detecting a difference in position between the light converged by the objective lens and the track on the optical disk. Included in the servo section of the optical disk apparatus are an amplifier for amplifying an output of the error detecting section with an amplification factor which is variable and a filter circuit for cutting off a frequency component of an output of the amplifying means, the cutoff frequency being variable. On the basis of the output of the filter circuit, a moving device moves the objective lens so that the difference between the converged light and said track is reduced. The amplification factor of the amplifier and the cutoff frequency of the filter circuit are determined in correspondence with the position of the objective lens. These amplification factor and cutoff frequency are prestored in a memory so that the corresponding amplification factor and cutoff frequency are read out therefrom in accordance with the current position of the objective lens.

Optical disk apparatus

Growing community of inventors

Kasuga, Japan

Kiyoyuki Suenaga