Recording medium, recording apparatus and recording method

Abstract

Optimum movement of first and last signal pulses based on the data pattern is determined before data recording to record marks in the correct position. A specific pattern signal is read from a disc track and digitized with an appropriate slice level by the digitizing circuit (115). A pulse position offset measuring circuit (120) then measures specific edge intervals in the resulting digital signal. Movement of the first and last pulse by the pulse moving circuit (110) is then set so that the offset between the measured edge interval and a predetermined standard edge interval is ideally zero.

Description

BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The present invention relates to a data recording medium, a recording apparatus and to a recording method for recording information to this data recording medium. [0003] 2. Description of Related Art [0004] Data recording devices for optically recording information, and particularly digital data, to a storage medium are commonly used as a convenient means of mass data storage. [0005] Phase change optical discs are one type of optical data recording medium. To record to a phase change optical disc a semiconductor laser emits an optical beam to a spinning disc to heat and melt a recording film on the disc. The achieved temperature and the cooling process (rate) of the molten film can be regulated by controlling the power of the laser beam, thereby inducing a phase change in the recording film. [0006] When laser power is high, the recording film cools rapidly from a high temperature state and thus becomes amorphous. Wh...

AI Technical Summary

Benefits of technology

[0131] According to the 61st aspect of the invention, in the recording method as set forth in the 57th aspect, group delay compensation is performed to minimize jitter in the reproduced test signal.

Problems solved by technology

In a direct overwrite recording method this can result in part of a mark not being overwritten or completely erased, resulting in a significant loss of signal quality due to signal crosstalk between tracks during reproduction.

This thermal interference can result in heat at the trailing edge of a recorded mark travelling through the following space, thus affecting heat distribution at the beginning of the next mark.

Heat at the beginning of one recorded mark can also travel back through the preceding space and adversely affect the cooling process of the preceding mark.

When such thermal interference occurs with conventional recording methods, the positions of the leading and trailing edges can shift, thus increasing the error rate during data reproduction.

Japanese Patent Application 5-279513 does not, however, teach a method for determining the optimum positions of the leading and trailing parts of a mark.

If the method of optimizing the leading and trailing edge positions is not defined, the reliability of the optimized recording will be low.

Furthermore, even if optimized recording is achieved, it will be at the expense of excessive time spent searching for the optimum position and excessive circuit cost.

A problem with this method, however, is that the edge of a recorded mark can move due to thermal interference as described above.

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