Matsushita Electric Industrial Co., Ltd.

Panasonic Corporation

Yuu Okada

Katsuya Watanabe

Mamoru Shoji

Yasumori Hino

Takahiro Sato

Takeharu Yamamoto

Kenji Fujiune

Jun Kikuchi

Takashi Kishimoto

Tetsuya Shihara

Akihiko Nishioka

Koujiro Okamoto

A recording power determination method for determining a recording power of an optical beam for recording data on an information storage medium includes the steps of recording test data on the information storage medium at a plurality of test recording powers; reading the test data recorded at each test recording power, generating a signal, and measuring a modulation factor of the signal corresponding to each test recording power; calculating a product of an n'th power of each test recording power and the corresponding modulation factor, thereby obtaining a plurality of products corresponding to the plurality of test recording powers, where n is a value of exponent and is a real number other than 1; calculating a first recording power based on the correlation between the plurality of test recording powers and the plurality of products; and calculating the recording power based on the first recording power.

Recording power determination method and device

An optical disc apparatus includes: a converging section for converging a light beam and irradiating a rotating information medium with the converged light beam; a moving section for moving the converging section, thereby moving a converging point of the converged light beam in a direction perpendicular to an information surface of the information medium; a converging state detection section for generating a focus servo signal which represents a converging state of the light beam on the information medium based on reflected light or transmitted light of the light beam from the information medium; a focus servo control section for controlling the moving section based on the focus servo signal, so that the light beam reaches a predetermined converging state on the information medium; and a focus pull-in section for turning ON the control by the focus servo control section, wherein the focus pull-in section turns ON the control by the focus servo control section in a case where the focus pull-in section determines that the converging point of the light beam is located in the vicinity of the minimum velocity position on the information medium axial deviation.

Optical disc apparatus

A laser power control apparatus is for use in an optical disk apparatus for recording information on an optical disk having at least a first layer and a second layer. The laser power control apparatus includes a power control section for controlling a laser element such that a power of a laser beam approaches a control target level; a change detection section for detecting that a recording condition for the optical disk has been changed; and a power adjustment section for adjusting the power of the laser beam for a recording film of the first layer, in accordance with an output from the change detection section. The power adjustment section determines the power of the laser beam for a recording film of the second layer, based on the power of the laser beam which has been adjusted for the recording film of the first layer.

Laser power control apparatus and method, an optical disk apparatus and a recording method

The optical disc apparatus comprises a convergence lens, a light detection devicefor outputting a first and a second detection signals after detecting reflected optical beam area by area, an actuatorfor shifting the convergence lens, a gain balance circuitfor changing a gain balance of the first and the second detection signals, an addition circuitfor outputting the addition signal AS after adding the first detection signal to the second detection signal in response to the shift in lens position and the change in gain balance made by the gain balance circuitand the actuator, and an addition signal measurement unitand a gain balance adjustment unitoperable to obtain the addition signal AS from the addition circuit, specify the gain balance that equalizes the detection sensitivities in the respective areas of the light detection devicebased on the obtained result, and control the gain balance circuitthat realizes the determined gain balance.

Optical disc apparatus, control device and control signal generation circuit

An optical disc device with high reliability, which is capable of performing a stable track jumping, is provided. In the optical disc device, a space (time interval) between an address part and the next address part in the address space measuring part inside the DSP is measured, and when the reproduction speed detected in the reproduction speed detection part based on the measuring result is faster than a predetermined reproduction speed, an application timing of an accelerating pulse is switched in the accelerating/decelerating pulse generator such that the application timing of an accelerating pulse or a decelerating pulse is matched with a transit timing in the address part.

Optical disc device

An optical disk apparatus includes a converging section for converging a light beam toward an information carrier; a moving section for moving the light beam converged by the converging section in a direction perpendicular to a surface of the information carrier; a light detector for detecting the light beam reflected by the information carrier; a convergence state detecting section for generating a convergence state signal representing a convergence state of the light beam at a convergence point on the information carrier and outputting a reproduction signal from the information carrier, based on the output from the light detector; a focus controller for driving the moving section to make the convergence state constant based on the convergence state signal and a prescribed target position; a reproduction quality signal detector for detecting a reproduction quality signal representing a quality of the reproduction signal based on the reproduction signal; a reproduction quality signal measuring section for changing the target position and measuring a value of the reproduction quality signal corresponding to each of the changed target positions; a reproduction quality signal characteristic determining section for determining a characteristic of the reproduction quality signal based on the value of the reproduction quality signal corresponding to each of the changed target positions; and a target position searching section for searching for an optimum target position of the focus controller for optimizing the value of the reproduction quality signal based on a determination result of the reproduction quality signal characteristic determining section.

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Moriguchi, Japan

Yuu Okada