Matsushita Electric Industrial Co., Ltd.

Panasonic Corporation

Yoshiyasu Nakayama

Harumitsu Miyashita

Masayoshi Nakamura

Yasuo Ueda

Emi Kitano

Hiroaki Shigematsu

The present invention provides a method for writing data on a multilayer optical disc with N information storage layers (where N is an integer and N&#x2267;2). The kdeepest one (where k is an integer and 1&#x2266;k&#x2266;N) of the storage layers of the multilayer optical disc is called a kinformation storage layer. The method includes the steps of: (A) finding the number of layers that an optical disc loaded into an optical disc drive has (disc type recognition); if the number of layers is X (which is an integer and X&#x2267;2), (B) tentatively writing data on a test write area of an minformation storage layer (where m is an integer and 1&#x2266;m&#x2266;X&#x2212;1), thereby determining a provisional initial optical recording power (performing OPC); (C) choosing an appropriate correction coefficient according to the level of a target layer, on which data needs to be written, and correcting the provisional initial optical recording power based on the correction coefficient chosen, thereby determining an initial optical recording power; and (D) starting writing the data on the target layer with the initial optical recording power.

Method for writing data on multilayer optical disc and optical disc drive

In an optical information reproduction apparatus having optical beam sources having at least two types of wavelengths, an object lens may be damaged by colliding with an information recording medium while driving a focus servo, which is caused by a fake signal generated due to an incompatibility of the wavelength in use with the information recording medium. To solve such a problem, in case the type of the information recording medium is unrecognizable and a focus servo is led in by using the optical beam source having the first wavelength, the focus servo is led in by using the second focus servo lead-in unit which is driven by an output of a near focus point detection unit during an operation of a second focus search unit which renders the object lens move away from the information recording medium.

Optical information reproduction method and apparatus

Growing community of inventors

Osaka, Japan

Yoshiyasu Nakayama