JPH02307007A - Defect inspection method for optical disk - Google Patents

Abstract

PURPOSE:To detect only a groove defect by making the detection data of an ID(identification code) part ineffective by a data processing part with the detection signals of an index detector and a rotational angle detector provided on a spindle. CONSTITUTION:The optical disk 1 is rotated on the spindle 1, the index detector 5 detects and outputs its index mark, and the rotary angle detector 6 detects and outputs its rotational angle theta. Further, the surface of the disk 1 is irradiated with a laser beam T to form a spot S and a light receiving device 4 detects primary diffracted light R1 and also detects scattered light from ID pits simultaneously. A defect detection part 8 detects the light receiving signals as a groove defect and the light receiving signal of the scattered light as a dummy defect and inputs them to a data processing part 9, which stores the data on a memory 9a. The processing part 9 inputs the index signal and rotary angle signal to find the radial position and angular position, data in the address on the memory 9a corresponding to the radius and angular position is made ineffective, and only groove defective data other than the defective data are outputted.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of Industry (-1)] The present invention relates to a defect@previous method for optical discs, and more particularly to group defect inspection in write-once optical discs.

[Prior Art] The field of use of optical discs as high-density recording media is rapidly expanding. FIG. 2(a) shows a write-once optical disc, in which a large number of r-shaped concentric circles la are provided on the disc l, and information pits are carved into the groups la during use.

Optical discs undergo various inspections during the manufacturing process, and methods for detecting group defects at the stage where groups are carved are already known. Figure 2(b).

This is illustrated by (c) and (d). In Figure (b), an optical disc 1 is rotated by a spindle 2, and a laser beam T is focused onto a spot S by a projection lens 3 and emitted in an X direction. In this case, if the diameter of spora l-8 is set to be 1 larger than the pitch interval of group la, then - IQ? The groups la lined up form a diffraction grating r, which reflects diffracted light with a regular intensity distribution. For example, the first-order light R1 (÷) of the diffracted light, or R1
(-) is received by the light receiver 4 or 4'. Now, figure (C
), when group la has a defect (f) such as collapse, the diffracted light in this portion decreases. When the spot S moves in the direction of the arrow, the light receiver 4 receives a signal (f) that is lower than the light reception level Ls for the normal group, as shown in FIG. 4(d). This is detected and treated as a defect.

[Problem to be Solved] Now, on a write-once optical disc, ID information is set after a group of [-] is engraved. Figure 3 (a), (b)
This is explained by dividing the surface of the disk 1 into multiple sectors S1 starting from the index mark (IND).
．． S2.・・・・・・Divide into sn. The narrow angular range δθ of the frontal region of each sector S is taken as the ID part, and as shown in Figure (b), the code such as the sector number is written in the pit 1.
b is engraved, and what follows is a data section where pits of information data are recorded. Such an ID is set, and a replica of the optical disc is manufactured using the original disc at a stage where no information data is recorded. 1 for this replica,
If the group inspection described above is to be carried out, ■1) Pit 1b
Therefore, the diffracted light changes, and it is detected as a pseudo defect even though there is no defect in the It) part. In response to this, several methods have been proposed for detecting defects in groups of ID sections by taking into account the influence of ID beat I, and some are effective.

However, all of those methods are slightly complicated P methods. On the other hand, since replicas are produced in large numbers, there is a need for quick inspection using a simple method, and as a next step, it is necessary to inspect for group defects only in the data section.

This invention was made in view of the following 11 circumstances, and I
This provides a method for inspecting only the data section for group defects, excluding the I) section.

[R stage to solve the problem] This invention provides a laser beam ray onto the surface of a write-once optical disc rotated by a spindle! ! (This is an inspection method for defect inspection of optical disks that scans in a spiral with a single beam and detects diffracted light by groups set on the surface.It is an inspection method for defect inspection of optical disks in which the optical disk is scanned in a spiral manner and diffracted light is detected by groups set on the surface. For the part II) in which rD pits are set in a certain angular range,
Detection signals from an index detector and a rotation angle detector provided on the spindle are input to a data processing section, and through data processing, detection data for the ID section is invalidated, and detection data for the data section is output as valid. .

[In the defect detection method described in Effect 1-1, all the diffracted light from the data section group and the diffracted yt or scattered light from the ID section group and its pits are detected. Based on the detection signals from the detector and the rotation angle detector, the data processing section invalidates the detection data of the ID section and only detects group defects in the data section.

[Embodiment] FIG. 1 shows a schematic diagram of a probe I in an embodiment of the optical disc defect inspection method according to the present invention. Diagram (a)
, the optical disk l to be inspected is rotated by a spindle 2, and an index (I) is detected by an index detector 5.
The rotation angle 0 of the disk 1 is detected by the rotation angle detector 6, and each detection (;
No. 1 is output. The defect detection optical system for the surface of the disk 1 irradiates the surface of the disk 1 with a laser beam T to form a spot S, as shown in FIG. The light is received by the device 4, and at the same time, the light scattered by the ID pits is also received. These light receivers 5) are level-adjusted by a suitable amplifier 7, and group defects are detected by a defect detector 8.
In addition, the light receiver 5f of the scattered light of the ID pit is detected as a pseudo defect, and the data of these defects and pseudo defects is input to the data processing section 9, and the 1', diameter and rotation angle of the disk (2) are input to the address 7. It is stored in the memory 9a. On the other hand, the index signal zJ and the rotation angle transformer are input to the data processing section 9, and by counting the inch 1 x signal, each N) starting from ゛lt, radial position return position, INF) is input.
The angle (1"l position of if - As the rotation angle detector 6, a rotary encoder with good resolution is used.

[Effects of the Invention] As is clear from the explanation below, in the optical disc defect inspection method according to the present invention, by using a simple software method, II) preventing pit pseudo defects from being detected as group defects; By applying this method, it is possible to efficiently inspect a replica of a write-once optical disc, which is highly effective.

[Brief explanation of the drawing]

FIG. 1 is a schematic block diagram of an embodiment of the optical disc missing 1fM scanning method according to the present invention, and FIG. 2(a)
, (b), (c) and (d) are explanatory diagrams of a group of optical disks for additional recording and a known group defect detection method,
FIGS. 3A and 3B are explanatory diagrams of ID information pits set on a write-once optical disc and pseudo defects caused by the ID information pits. 1...Writable optical disc, la...Group, 1b
...Pit, 2...Spindle, 3...
・Emission lens, 4.4'...Receiver, 5...
・Index detector, 6...Rotation angle detector, 7・
...Amplifier, 8...Defect detection section, 9...
data processing unit, 9a...memory; Special Engineering 1 Applicant [1 Ritsunen R Engineering Co., Ltd. Agent Patent Attorney: Kajiyama Kōre Patent Attorney L: Tomi Yamaki” - Male (b) ○ 2 (C) (d)

Claims (1)

[Claims] A defect in an optical disc in which the surface of a write-once optical disc rotated by a spindle is irradiated with a laser beam to scan it spirally, and the diffracted light of the laser beam is detected by a guide groove (hereinafter referred to as a group) set on the surface. In the inspection, the surface of the optical disk is equally divided in the circumferential direction with the index mark as the starting point, and for each sector, identification code (ID) pits are set in a certain angular range in the ID section, and the pits are set on the spindle. Detection signals from the index detector and the rotation angle detector of the optical disc are input to a data processing section, and the detection data for the ID section is invalidated through data processing, and the detection data for the data section is output as valid. A method for inspecting optical discs for defects.