JPH0233740A - Optical disk - Google Patents

Abstract

PURPOSE:To obtain highly reliable read data written in the disk without changing recording power in response to the distance from the center by varying the width of the groove for recording data according to the linear speed. CONSTITUTION:The width of the groove in which data is recorded is varied according to the linear speed of the disk. Namely, grooves near outer periphery are narrower than those in the center part. Thus, the recording power can be kept constant without affected by the linear speed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a magneto-optical disk for an optical recording and reproducing device that records and reproduces information using a semiconductor laser as a light source.

[Conventional technology]

FIG. 2 shows a cross-sectional view of a magneto-optical disk of an optical recording/reproducing device using a conventional semiconductor laser as a light source. A focused beam 1 focused by an objective lens passes through a substrate 2,
The recording film 3 is irradiated to perform recording, reproduction, and erasing. When recording, the recording film on the groove 4 is heated by the focused beam 1 and a recording bit is formed. At this time, since the recording film on the wall of the groove 4 is thin, heat conduction occurs on the wall. This results in a shape similar to the recording bit 5 shown in FIG.

In continuous servo, the width of the groove is the same from the inner circumference to the outer circumference, and as a result, the optimum recording power and optimum erasing power change depending on the linear velocity.

In addition, in the sampling servo method, as shown in FIG. 3, there are no grooves and there is no wall to block heat conduction, so the recording pit has the shape shown in 6. Recording and erasing conditions are determined by changing the optimum recording power and optimum erasing power in accordance with the linear velocity in the same way as for continuous servo.

[Problem to be solved by the invention]

However, in the above-mentioned conventional technology, the recording power must be changed depending on the radial position of the disk, and the laser power must be increased at the outer periphery of the disk, which shortens the life of the laser. In the sample servo method, in addition to the above, the recorded bits become larger due to heat conduction during recording, causing signal crosstalk.

The present invention is intended to solve these conventional problems, and its purpose is to record bits that will allow highly reliable read data to be obtained without changing the recording power depending on the disk radius. The object of the present invention is to provide a magneto-optical disk that can be used in sample servo and has less signal crosstalk.

[Means to solve the problem]

The optical disc of the present invention has the following features: (1) (a) An optical disc for an optical recording and reproducing device that records and reproduces information using a semiconductor laser as a light source, (b) The width of the groove (between the grooves) for recording data is set by a line. (2) (C) The optical disc records and reproduces information using a sampling servo method that performs tracking servo using wobble pits, etc. on the disc, (d) The present invention is characterized in that a groove is provided in a data area to be recorded and reproduced, and (e) the width of the groove is changed between an inner circumference and an outer circumference.

〔Example〕

FIG. 1 shows the recording pit shape of the magneto-optical disk of the present invention from the outer circumference to the inner circumference. The groove pitch is constant on both the inner and outer circumferences. 7 shows the bit shape recorded in the groove on the outer periphery, 8 shows the recorded pit in the center, and 9 shows the recorded pit in the inner periphery. Since the bit width is limited by the groove, the bit width and groove width are approximately equal, and the bit width becomes narrower at the outer periphery. FIG. 4 shows the groove width with respect to the disk radius of the present invention, and the optimum recording power with respect to the disk radius is shown in the fifth section. Therefore, it can be seen that the recording power is limited by changing the groove width, and the recording power is kept constant regardless of the linear velocity.

FIG. 6 shows the pit shape when there is a groove in the sample servo in the second embodiment of the present invention. The bit 10 indicated by diagonal lines is the bit shape when there is a groove,
A portion 11 indicated by a dotted line is the bit shape without a groove. In this way, the bit width can be restricted by the grooves, signal cross-tock can be reduced, and the track pitch can be narrowed for higher density recording.

〔Effect of the invention〕

As described above, according to the present invention, the following effects are brought about. Optimal recording and erasing can be performed with constant power without changing the recording power and erasing power depending on the linear velocity.

In addition, in sampling servo', signal crosstalk between adjacent tracks can be suppressed, and the track pitch can be reduced for high-density recording.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the shape of pits on a recording film of the present invention. FIG. 2 is a diagram showing the cross-sectional shape of the media. FIG. 3 is a diagram showing the shape of bits on the disk. FIG. 4 is a diagram showing the groove width with respect to the disk radius. FIG. 5 is a diagram showing recording power versus disk radius. FIG. 6 is a diagram showing a bit shape for a second embodiment of the present invention. 1...Focused beam 2...Substrate 3...Recording film 4...Groove 5...More than recording pit

Claims (2)

[Claims] (1) (a) In an optical disk of an optical recording and reproducing device that records and reproduces information using a semiconductor laser as a light source, (b) changing the width of the groove (between grooves) in which data is recorded in accordance with the linear velocity. An optical disc featuring (2) (c) In the optical disc in which information is recorded and reproduced by a sampling servo method that performs tracking servo using wobble pits or the like on the disc, (d) grooves are provided in the data area where information is recorded and reproduced. 2. The optical disc according to claim 1, wherein: (e) the width of the groove is changed between an inner circumference and an outer circumference.