JP2551063B2 - Light disk - Google Patents

Description

The present invention relates to an optical disk used in an optical disk device,
In particular, the present invention relates to an optical disc that mainly reproduces or records and reproduces a moving image, a still image, a sound, a code signal, or the like, which is mainly a video signal.

[Conventional technology]

Conventionally, as this type of disk, there is, for example, one shown in FIGS. 2 (a) and 2 (b).

In the optical disc 1 shown in FIG. 2 (a), concentric grooves 2a and 2b are formed. In this case, when the optical disc 1 makes one revolution during continuous reproduction, the optical head needs to be track-jumped inward or outward. However, such a track jump is usually the cause of difficulty in controlling the servo of the optical head drive unit and the instability of the reproducing operation.

Therefore, as a structure for eliminating the track jump, a structure like the optical disk in FIG. 2B is considered. This is one in which clockwise or counterclockwise spiral grooves are formed on the optical disc 1 as grooves 3a and 3b, respectively. With this configuration, the optical head is a groove.
Since it was accessed along the spirals of 3a and 3b, there was no need for truck jumping.

By the way, recently, an increasing number of methods use a plurality of optical heads in order to record more information on an optical disk. In such a case, it is better to move one of the optical heads from the center side to the outer circumference side and move the other from the outer circumference side to the center side rather than moving the plurality of optical heads in the same direction. It has been researched that the total speed becomes constant and high density recording is possible, which is advantageous.

However, in the optical disk as shown in FIG. 2 (b), if the above method is applied, one optical head can be continuously reproduced without a track jump, but the other optical head rotates in the direction opposite to the spiral, so that the optical disk rotates. It is necessary to make a jump of 2 tracks per revolution.

[Problems to be solved by the invention]

As described above, in the conventional optical disk, when reproducing using a plurality of optical heads, the track head jump of the optical head is necessary in FIGS. 2A and 2B, so that the servo of the optical head drive control unit is required. There was a problem that the operation became unstable.

[Means for solving problems]

In the present invention, the radius r1 to the radius r1 + m (where 0 <m <
A spiral groove in the clockwise or counterclockwise direction formed in the area up to (r2-r1) / 2) and radius r2-n (where 0 <n <(r2-r1) / 2) to radius r2 And a spiral groove in the opposite direction to the groove.

[Action]

In the present invention, the clockwise and counterclockwise grooves enable continuous reproduction of a plurality of optical heads without causing a track jump.

Example Next, an example of the present invention will be described with reference to the drawings.

In FIG. 1, 4a is the radius from the radius r1 of the optical disk 10.
A spiral groove 4b is formed in the clockwise direction in the region of r2, and a spiral groove 4b is formed in the counterclockwise direction in the region of radius r2 to radius r3. Also, h _a , h
_b is an optical head, an optical head h _a in the center of circle direction, the optical head h _b is assumed to be moved toward the outer circumference.

When the first light head h _a, h _b and were located at a radius r2, the clockwise rotation of the optical disk 10, each groove 4a after t seconds, 4b spirally along connexion light head h _a of,
h _b moves by the amount of movement k, and each radius (r2-k),
It will be located at (r2 + k). Therefore, it is clear that the total value of the radial positions of the two optical heads h _a and h _b is always 2 · r2.

Further, the radial position than that proportional to the linear velocity, these optical head h _a, also the sum of the linear velocity of h _b becomes constant.

As described above, in the present embodiment, the grooves 4a and 4b are formed in the clockwise and counterclockwise spiral shapes, respectively.
h _a and h _b can be played continuously without track jumping.

〔The invention's effect〕

As described above, according to the present invention, since the spiral grooves in the clockwise direction and the counterclockwise direction are formed in the respective predetermined regions, continuous reproduction can be performed without a track jump even when a plurality of optical heads are used. In addition, since the servo operation is stable and the linear velocity is constant, higher density recording is possible.

[Brief description of drawings]

FIG. 1 is a plan view showing an embodiment of the present invention, and FIGS. 2 (a) and 2 (b) are plan views of a conventional example. 4a, 4b …… groove, 10 …… optical disc, h _a , h _b …… optical head.

Claims (1)

(57) [Claims] 1. An optical disk having a region from radius r1 to radius r2 (r1 <r2) as a reproducible or recordable / reproducible region, wherein radius r1 to radius r1 + m (where 0 <m <(r2-r1) / 2)
To the clockwise or counterclockwise spiral groove formed in the area up to the radius r2-n (where 0 <n <(r2-r1) / 2) to the radius
An optical disk, characterized in that a spiral groove formed in a direction opposite to the groove is provided in a region up to r2.