JPS63152038A - Optical disk faulted position retrieving system - Google Patents

Abstract

PURPOSE:To attain fault observation in which the kind of fault is discriminated by including information concerning a faulty part in the record of a form alteration area and an optical constant alteration area or an area whose magnetic direction is different near the faulty part. CONSTITUTION:In an optical disk reproducing optical system, as soon as the faulty part 1 of the optical disk is detected and the kind of fault is decided, and immediately after the decision, a recording laser light beam modulated by the information about the fault records in a certain period so as to form a marking area 2. At the time of retrieving the fault position 1, the marking area 2 is retrieved first and the faulty part 1 can be found by tracing back the marking area 2 in a direction opposite to a recording direction. Moreover, it can be informed that a reproducing optical system and a signal process system decides what kind of fault the fault is.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for searching for defect positions on optical discs.

(Prior art) The defect occurrence rate, which is one of the important performances of optical discs, is desired to be as low as possible. Therefore, in order to reduce the defect occurrence rate, it is necessary to know the cause of defect occurrence, and to Observation using a microscope (such as an optical microscope or an electron microscope) is an important method.

A defective portion of an optical disk is determined by processing a reproduced signal using a reproduction optical system and checking whether an error has occurred. Conventionally, the defect occurrence position at this time is measured as follows. If track address information and sector address information are already recorded on the optical disc, each address information is read at the time of defect mi measurement. If there is no address information on the optical disc, a reproduction radius position reading mechanism of the reproduction optical system and a rotation angle reading mechanism are attached to the optical disc rotation axis, and the reproduction radius and disc rotation angle are read when defects are observed. When observing a defective portion of a disk whose defect occurrence position has been read as described above using a microscope, the defective portion is searched for by observing the vicinity of the disk radial position and rotational angle position read at the time of defect observation.

In addition, as a method that the present inventors have already proposed that makes it easy to search for defect positions, a shape-changing area with a length of about 100 μm to about 5C11 is created near the defect position detected by the optical disc playback system. There is a method in which regions of varying optical constants or regions of different magnetization directions are recorded on an optical disk (hereinafter these regions are referred to as marking regions), and these marking regions are searched using a microscope to search for defect positions.

(Problems to be Solved by the Invention) As mentioned above, in the method of searching for defective parts by observing the vicinity of the disk radial position and rotational angle position read during defect observation, it is difficult to increase the recording density due to the positional accuracy. When there are several types of defects near the defect observation position, it becomes impossible to distinguish between them. In addition, the method of searching the marking area near the defect position has good defect search efficiency, but if multiple types of defects are detected on the same optical disc and a marking area for defect search is recorded for each, the marking area can only be searched. However, there was a drawback that it was not possible to determine what type of defect it was.

(Means for Solving the Problems) The gist of the present invention is a method for searching for defect positions by recording shape change regions, optical constant change regions, or regions with different magnetization directions near defective parts of an optical disk. An optical disc defect position search method is characterized in that information regarding the defective portion is included in the recording of a shape changing region, an optical constant changing region, or a region having a different magnetization direction near the defective portion.

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

FIG. 1 shows a schematic diagram of the arrangement of the defective portion 1 and the marking area 2. A defective portion 1 of the optical disk is detected by an optical disk reproducing optical system to determine the type of defect, and immediately after that, recording is performed for a certain period of time with a recording laser beam modulated according to defect information to create a marking area 2. When searching for the defect position 1, first search the marking area 2, and trace the marking area 2 in the opposite direction to the recording direction.
The defective portion 1 can be found, and furthermore, it is possible to know what type of defect has been determined by the reproduction optical system and the signal processing system.

(Example) FIGS. 2 and 3 show microscopic photographs of a defective portion due to a missing recording bit and an extra defective portion searched for using the defect position searching method of the present invention.

The defect information of missing recorded bits in FIG. 2 was recorded in a marking area by increasing the modulation pulse width, and the extra defect information in FIG. 3 was recorded in a marking area by shortening the modulation pulse width. This allows the type of defect recorded in the marking area to be determined.

(Effects of the Invention) As described above in detail, by using the optical disk defect position search method according to the present invention, it becomes possible to observe defects with defect type discrimination.

[Brief explanation of the drawing]

Figure 1 is a diagram showing the arrangement of defective parts and marking areas;
FIGS. 2 and 3 are IR microphotographs in which defective areas due to missing recorded bits and extra defective areas were searched. In the figure, 1 is the defective area and 2 is the marking area. Applicant: 5-33-1 Shiba, Minato-ku, Tokyo (423) NEC Corporation Representative: Tadahiro Sekimoto 4, Agent: Sumitomo Sanda Building, 37-8 Shiba 5-chome, Minato-ku, Tokyo 108 (
Contact information: NEC Corporation Patent Department) 5. Date of amendment order: March 31, 1988 (shipment date) 6. Detailed explanation of the invention in the specification subject to amendment Column for brief explanation of the drawings 7. Amendment to drawings Contents 1) The embodiments from page 5, line 2 to page 5, line 10 of the specification are amended as follows. (Example) Fig. 2 and Fig. 3 are schematic diagrams of micrographs obtained by searching for defective areas of missing recording bits and extra defective areas using the defect location search method of the present invention. The defect information of missing recorded bits was recorded in the marking area by increasing the modulation pulse width, and the extra defect information in Figure 3 was recorded in the marking area by shortening the modulation pulse width.As a result, the defect recorded in the marking area 2) The column for the brief explanation of the drawings in the specification should be amended as shown in the attached sheet. 3) Figure 2 of the drawings attached to this application is amended to look like an attached drawing. 4) Figure 3 of the drawings attached to this application is amended to look like an attached drawing. Brief explanation of attached drawings Figure 1 is a diagram showing the arrangement of defective parts and marking areas;
FIGS. 2 and 3 are diagrams schematically showing micrographs obtained by searching for defective areas due to missing recording bits and extra defective areas. In the figure, 1 is a defective part and 2 is a marking area.

Claims (1)

[Claims] In a method in which a defect position is searched by recording a shape change region, an optical constant change region, or a region with a different magnetization direction near the defective portion of an optical disk, the shape change region, optical constant change region, or magnetization direction An optical disc defect position search method characterized in that information regarding the defective portion is included in recordings of different areas.