JPH0695399B2 - Optical disk defect location search method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for searching for a defective position on an optical disc.

(Prior Art) It is desired that the defect occurrence rate, which is one of the important performances of optical disks, be as low as possible. Therefore, in order to reduce the defect occurrence rate, it is necessary to know the cause of the defect occurrence, and observing the defective portion with a microscope (optical microscope, electron microscope, etc.) is one of the important means.

The defective portion of the optical disc is determined by processing a reproduced signal using a reproducing optical system and determining whether or not an error has occurred. Conventionally, the defect occurrence position at this time is observed as follows. When the track address information and the sector address information are already recorded on the optical disc, each address information is read at the time of observing a defect. If there is no address information on the optical disk, a read radius position reading mechanism of the read optical system and a rotation angle reading mechanism on the optical disk rotation axis are attached to read the read radius and the disk rotation angle when a defect is observed. When observing the defective portion of the disk whose defect generation position has been read as described above using a microscope, the defective portion is searched by observing the vicinity of the above-mentioned disk radial position and rotation angle position read at the time of defect observation.

(Problems to be Solved by the Invention) When a defect is searched and a defect is observed by the above method,
When the size of the observable symmetry defect is about 1 μm, there are the following problems. Even if the defect area is searched by observing the disk radial position and the rotation angle position read at the time of defect observation, if the microscope magnification is increased, the observation field becomes narrower, making it difficult to find the defect area. When the magnification is reduced, the defect itself becomes invisible. For this reason, it is difficult to search for the defective portion. Further, even if a position which is expected to be a defective portion is found, it is impossible to judge whether or not the portion is judged to be defective by the reproducing optical system.

An object of the present invention is to solve the above problems and provide an optical disk defect position searching method for efficiently searching for a defective position on an optical disk.

(Means for Solving the Problems) The gist of the present invention is to provide a method of searching for a defect position of an optical disc, in which a shape having a predetermined length is provided in the vicinity of the defect position detected by the reproduction optical system of the optical disc. A change region, an optical constant change region, or a region having a different magnetization direction is recorded on an optical disk by using a reproduction optical system or an optical system independent of the reproduction optical system, and a shape change region or an optical constant change region near the defect position is recorded. Alternatively, the optical disk defect position searching method is characterized in that a defect position is searched by searching a region having a different magnetization direction with a microscope.

The length of the region is longer than 1 μm, preferably 10 μm.
It is better to be more than μm and about 10 cm.

(Operation) The present invention will be described in detail below with reference to the drawings.

In the following description, a shape change area, an optical constant change area, or an area having a different magnetization direction, which is recorded in the vicinity of the defect position detected by the reproduction optical system of the optical disc, is referred to as a marking area.

FIG. 1 shows a schematic view of the arrangement of the defective portion 1 and the marking area 2. Immediately after the defective portion 1 of the optical disc is detected by the optical disc reproducing optical system, recording is performed for a certain period of time to create a marking area 2. When searching for defect locations,
First, the marking area 2 is searched, and the marking area is traced in the opposite direction to the recording direction, whereby the defective portion 1 can be easily found, and the efficiency of defect observation can be improved.

(Embodiment 1) FIGS. 2 and 3 are schematic diagrams of micrographs in which a defective portion where a recording bit is missing is searched using the defect position searching method of the present invention.
Shown in the figure. FIG. 2 is a schematic view of a marking area observed with an optical microscope at a magnification of 100 times. Although there is a defective portion at the tip of the marking area, the defective portion cannot be seen at this magnification. FIG. 3 is a schematic diagram when the tip portion of the marking area in FIG. 2 is enlarged to a magnification of 2000 times. At this magnification, the defective portion can be observed.

(Example 2) FIG. 4 shows a schematic diagram of a micrograph of an extra defect portion searched using the defect position searching method of the present invention. FIG. 4 is a schematic diagram in which the tip of the marking area is enlarged (magnification: 1000 times) as in FIG. At this magnification, the defective portion can be observed.

(Effect of the Invention) As described in detail above, by using the optical disk defect position searching method according to the present invention, it is possible to search for defects at a low magnification, speed up the defect observation of the optical disc, and improve the efficiency of defect observation. Can be improved.

[Brief description of drawings]

FIG. 1 is a diagram showing the arrangement of defective portions and marking areas,
2, 3 and 4 are schematic diagrams showing micrographs of the defective portion and the marking area. In the figure, 1 is a defective portion and 2 is a marking area.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A 63-152038 (JP, A) JP-A 63-152039 (JP, A) JP-A 63-117245 (JP, A) JP-A 63- 152040 (JP, A)

Claims (1)

[Claims] 1. A method of searching a defect position of an optical disc, wherein a shape change region or an optical constant change region of a predetermined length or a region having a different magnetization direction is provided in the vicinity of the defect position detected by a reproduction optical system of the optical disc. Recording on an optical disc using a reproduction optical system or an optical system independent of the reproduction optical system, a shape change region near the defect position, an optical constant change region, or a region with a different magnetization direction is searched with a microscope to detect the defect position. A method for searching the position of an optical disk defect, which comprises searching.