JPH02187976A - Optical disk - Google Patents

Abstract

PURPOSE:To automatically discriminate a correct disk rotating direction and to supply a reference rotating direction signal for showing the correct disk rotating direction to an optical disk device by providing a signal for showing the reference rotating direction on a specific radial direction of the disk surface. CONSTITUTION:When a double access optical disk 1 is installed in an optical disk device, a reflection factor of a concentric circle-like area 11a or 11b having a signal for showing the reference rotating direction of a first and a second optical disks 1a, 1b which prescribe the counterclockwise direction or the clockwise direction, respectively indicated with an arrow 1a or 1b as a normal use state is detected. As a result, the double access disk 1 is rotated immediately in the normal direction, and a recording/reproducing or erasing operation is executed quickly.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an optical disc on which information is recorded, reproduced, or erased using optical means.

[Conventional technology]

Conventional optical discs are used by being attached to an optical disc device that has a spindle that always rotates in the same direction of rotation, so they do not have marks specifically indicating the rotational direction in which the optical disc should be used.

[Problem to be solved by the invention]

By the way, as the performance of optical disks increases, optical disk devices that use optical disks that have recording areas on both sides for simultaneous recording, playback, or erasing are being considered. The disc rotation directions during recording and reproduction are opposite to each other.

Therefore, if a double-sided access optical disc is mistakenly loaded into an optical disc device with the front and back sides reversed, there is a problem that recording/reproducing or erasing operations cannot be performed. In addition, if it is detected that recording, playback, or erasing cannot be performed, and measures are taken to turn the double-sided access optical disc upside down or reverse the direction of rotation of the spindle, correct recording, playback, or erasing can be performed. The drawback is that it takes a long time to stop and start the spindle before it can operate normally.

An object of the present invention is to eliminate these drawbacks, to automatically identify the correct disk rotation direction, and to supply a reference rotation direction signal indicating the correct disk rotation direction to an optical disk device without rotating the optical disk. Our goal is to provide optical discs.

[Means to solve the problem]

In order to achieve the above object, the optical disc according to the present invention has a signal indicating the reference rotation direction at a specific radial position on the disc surface.

〔Example〕

Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

FIGS. 1(a), 1(b), and 1(c) are conceptual diagrams showing one embodiment of the present invention.

The double-sided access optical disc 1 is a first optical disc 1 whose normal use state is defined as being in the counterclockwise direction indicated by arrow a.
a, and a second optical disc 1b whose normal use state is defined as being clockwise as indicated by an arrow. The first and second optical discs 1a and lb have concentric regions 11a and 11b having mutually different reflectances and serving as reference rotation direction signals at specific radial positions.

When the double-sided access optical disc 1 of the present invention is installed in an optical disc device, the concentric area 11a or 11
Detect the reflectance of b. That is, by reading the reference rotation direction signal, the double-sided access optical disk 1 can be immediately rotated in the normal direction, and recording/reproducing or erasing operations can be performed promptly.

Note that the concentric region 11a or 11b may be further divided into a plurality of concentric regions, and the reflectance of each region may be changed in a specific pattern.

In this case, after the optical disk is mounted, the optical head is moved slightly in the disk radial direction and the specific pattern is detected, thereby ensuring accurate reference rotation so as not to be affected by reflectance fluctuations due to variations in optical disk manufacturing. It is possible to detect direction signals.

In addition, in this embodiment, a two-disc bonded optical disc for the purpose of simultaneous access on both sides was explained, but a single-disc disc with only single-sided access, and an optical disc that uses both sides and uses one side at a time by rotating in the same direction are also applicable. It is also effective to record a signal indicating the reference rotation direction at the same specific radial position as in the previous embodiment. As a result, an appropriate disk rotation direction can be automatically and quickly selected for the various types of disks mentioned above when the optical disk device is installed.

In this embodiment, the difference in reflectance is used as the reference rotation direction signal, but the same effect can be obtained by other means such as a difference in track pitch.

〔Effect of the invention〕

As described above, the optical disc of the present invention has a reference rotation direction signal at a specific radial position, so that it can be accessed simultaneously on both sides of an optical disc or a single-plate disc.

To provide an effect in which the correct disk rotation direction can be immediately detected before rotating the disk, regardless of which type of optical disk is used, such as an optical disk that uses both sides and uses one side at a time in the same rotational direction.

[Brief explanation of the drawing]

FIG. 1(a) is a plan view showing one embodiment of the present invention, FIG. 1(b)
is the same side view, and (C) is the same bottom view. 1...Double-sided access optical disc LA, LB...Optical disc

Claims (1)

[Claims] (1) An optical disc characterized by having a signal indicating a reference rotation direction at a specific radial position on the disc surface.