Matsushita Electric Industrial Co., Ltd.

Yasuhito Soma

Kazuhiko Kouno

Akira Matsubara

Masayuki Shibano

The present invention provides an optical disc apparatus which solves a problem that the tracking control takes off when an objective lens is displaced in the tracking direction due to its weight. In this optical disc apparatus, a spot position detectorgenerates a spot position signal which indicates a position of a light spot on a light receiving element, and supplies the signal to a traverse loop filterand a spot position loop filter. A controllersupplies an output from the spot position loop filterto a tracking actuator, before supplying an output from the traverse loop filterto a traverse motor, previously moves the light spot near the center of the light receiving element, and starts the traverse control in a state where a value of the spot position signal at starting of the traverse control is reduced.

Optical disc apparatus having compensation for objective lens dislocation, and method therefor

In an optical disc device that selectively implements a tracking servo and a spot position servo, a discontinuation cancellation unit is provided so that, when switching from the tracking servo to the spot position servo, and when switching in the opposite direction, the low-frequency component of the tracking drive signal and the low-frequency component of the spot position servo connect smoothly so that there is no step difference.

Optical disc device

The present invention provides an optical disc apparatus which solves a problem that the tracking control takes off when an objective lens is displaced in the tracking direction due to its weight. In this optical disc apparatus, a spot position detector generates a spot position signal which indicates a position of a light spot on a light receiving element and supplies the signal to a traverse loop filter and a spot position loop filter A controller supplies an output from the spot position loop filter to a tracking actuator before supplying an output from the traverse loop filter to a traverse motor previously moves the light spot near the center of the light receiving element and starts the traverse control in a state where a value of the spot position signal at starting of the traverse control is reduced.

Optical disk apparatus having compensation for objective lens dislocation

The present invention provides an optical disc apparatus which solves a problem that the tracking control takes off when an objective lens is displaced in the tracking direction due to its weight. In this optical disc apparatus, a spot position detector generates a spot position signal which indicates a position of a light spot on a light receiving element , and supplies the signal to a traverse loop filter and a spot position loop filter . A controller supplies an output from the spot position loop filter to a tracking actuator , before supplying an output from the traverse loop filter to a traverse motor , previously moves the light spot near the center of the light receiving element , and starts the traverse control in a state where a value of the spot position signal at starting of the traverse control is reduced.

An optical disk apparatus for recording and reproducing data to and from an optical disk has a pit area where data are recorded along a track by pits and a groove area where grooves are formed along a track to record data. The optical disk apparatus includes an optical head for projecting a light beam on the optical disk and a photodetector array for receiving the reflected light. A preamplifier is connected to the photodetector array for producing a tracking error signal and an RF signal representing the pits. The tracking error signal is used as a clock signal in flip-flops and the RF signal is used as an initial setting signal, so that the flip-flop produces a signal indicating that the optical head is in the pit area.

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Hirakata, Japan

Yasuhito Soma