JPH0224540A - Optical disk checking apparatus - Google Patents

Abstract

PURPOSE:To shorten the checking time to a large extent without decreasing checking accuracy excessively by checking a track on an optical disc, jumping a specified number of tracks without checking, and checking a track beyond said jumped tracks. CONSTITUTION:Optical heads 2a and 2b detect whether a defect is present in the first track on an optical disc 1. When the checking is finished, a predetermined number of (n) pieces (n<=20) of tracks are jumped, and a defect in the next track is checked. This operation is repeated. Whether a defect is present or not is detected for every (n) pieces of tracks. Defects are uniformly distributed on the optical disc 1. Even if the tracks to be checked are thinned, the rate of the defect length with respect to the checking length, i.e. the defect rate, can be suppressed with respect to the case wherein all tracks are checked if the thinning is performed evenly. The errors can be suppressed to several % or less.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an optical disc inspection device, and in particular, a tracking servo is applied to each of a large number of layered tracks formed on an optical disc to detect scratches and the like on the optical disc. The present invention relates to an optical disc inspection device for inspecting defects in an optical disc.

[Prior Art] FIG. 3 is a diagram showing an example of an optical disc. Although a large number of layered tracks are formed on the surface of the optical disc 1, defects such as uneven scratches may occur during the manufacturing process. Since defects on the disk surface directly affect the read signal, it is necessary to discover them and eliminate optical disks with many defects. Conventionally, an optical pickup was used to make a light beam follow the tracks on the disk surface, and all tracks were inspected for defects.

[Problems to be Solved by the Invention] However, although the method described above has the advantage of being able to detect all defects on the optical disc 1, the inspection time becomes long. This is particularly inconvenient when selecting optical discs 1 at a mass-produced level, and faster inspection is required.

Therefore, the main object of the present invention is to provide an optical disk inspection apparatus that can reduce the number of inspection tracks and shorten inspection time.

[Means for Solving the Problems] The present invention provides an optical disc inspection apparatus that inspects defects such as scratches on an optical disc by applying a tracking servo to each of a large number of layered tracks formed on an optical disc. After a certain track is inspected, a predetermined number of tracks are not inspected, and the next track is inspected.

[Function] In the optical disk inspection apparatus according to the present invention, after inspecting one track, the inspection time for n tracks is omitted, thereby reducing the inspection time to 1/(n+1).

[Embodiment of the Invention] FIG. 1 is a flow diagram for explaining the operation of an embodiment of the invention, and FIG. 2 is a specific block diagram of the embodiment of the invention.

First, the configuration of an embodiment of the present invention will be described with reference to FIG. Although not shown, an optical disk 1 is placed on a spindle motor, and the spindle motor is servo-controlled by a spindle servo circuit 13.

Two sets of detection devices are provided to detect defects on the surface of the optical disc 1. The reason why two sets of detection devices are provided in this way is to cut the inspection time in half.

One inspection device includes an optical head 2a. This optical head 2a is provided with an optical system for irradiating laser light onto the optical disc 1 and detecting the reflected light. The optical head 2a is driven by a linear motor 3a and is configured to be able to slide on an air slide 4a.

The distance that the optical head 2a has slid is detected by the linear scale 5a. The output detected by the optical head 2a is given to a focusing servo circuit 8a, a tracking servo circuit 9a, a laser power servo circuit 10a, and an RF signal processing circuit 12a via a detection circuit 6a.

The focusing servo circuit 8a performs focusing servo control to focus the laser beam spot onto the destination disk 1, and the focusing servo circuit 9
The circuit a performs tracking servo control so that the laser beam spot follows the track on the optical disc 1, and the laser power servo circuit 10a performs laser power servo control to adjust the intensity of the laser beam. . Further, the detection output of the linear scale 5a is processed by the linear scale signal processing circuit 7a and then given to the slide servo circuit 11a. The slide servo circuit 11a drives the linear motor 3a to perform slide servo control so that the optical head 2a slides on the air slide 4a. Focusing servo circuit 8a.

The respective outputs of the tracking servo circuit 9a, the laser power servo circuit 10a, and the slide servo circuit 11a are given to the microprocessor 14. In addition, RF
The signal processing circuit 12a processes high frequency components contained in the output of the detection circuit 6a.

The other detection circuit is configured similarly, and the optical head 2b
Near motor 3b, air slide 4b, linear scale 5b, detection circuit 6b; asscale signal processing circuit 7
b, a focusing servo circuit 8b, a tracking servo circuit 9b, a laser power servo circuit 10b, a slide servo circuit 11b, and an RF signal processing circuit 12b.

An input section 15 is connected to the microprocessor 14, and necessary data for inspecting the optical disc 1 is inputted from this input section 15. Further, the microprocessor 14 is connected to a computer 16, and a block 17 for plotting the inspection results of the inspected optical disk is connected to the computer 16.

Next, with reference to FIG. 1 and FIG. 2, a specific operation of an embodiment of the present invention will be described.

The optical heads 2a and 2b detect whether or not there is a defect in the first track on the optical disc 1, and when the detection is completed, they jump a predetermined number of days (n≦20) tracks and start the next track. Inspect for defects. This operation is repeated to detect whether or not there is a defect every 5.0 tracks.

As shown in FIG. 3 above, the optical disc 1 has defects uniformly distributed, so even if the tracks to be inspected are thinned out, if the thinning method is uniform, the inspection length will be °The error in the defect length ratio, that is, the defect rate, was suppressed to a few percent or less compared to when all tracks were inspected.

This shows that the defect has a certain width and has characteristics that are correlated in the radial direction.

Note that depending on the inspected defects or the distribution of scratches on the optical disc 1, whether or not the optical disc 1 can be used is determined manually.

[Effects of the Invention] As described above, according to the present invention, after inspecting a certain track on an optical disk, a predetermined number of tracks are not inspected, and the next track is inspected. Therefore, compared to the case where all tracks are inspected for defects, inspection time can be significantly shortened without significantly reducing inspection accuracy.

[Brief explanation of the drawing]

FIG. 1 is a flow diagram for explaining the operation of one embodiment of the present invention. FIG. 2 is a concrete block diagram of an embodiment of the present invention. FIG. 3 is a diagram showing an example of an optical disc. In the figure, 1 is an optical disk, 2a, 2b are optical heads, 3a, 3b are linear motors, 4a, 4b are air slides, 5a, 5b are linear scales, 5a, 5b are detection circuits, 7a, 7b are linear scale signal processing circuit, 8g,
8b is a focusing servo circuit, 9a and 9b are tracking servo circuits, 10a and 10b are laser power servo circuits, 11a and llb are slide servo circuits, 12a
12b is an RF signal processing circuit, 13 is a spindle servo circuit, 14 is a microprocessor, 15 is an input section, 16 is a computer, and 17 is a plotter.

Claims (1)

[Claims] In an optical disk inspection apparatus that applies tracking servo to each of a large number of layered tracks formed on an optical disk to inspect defects such as scratches on the optical disk, after inspecting a certain track on the optical disk, An optical disk inspection device characterized in that the apparatus jumps to a predetermined number of tracks without inspecting them and inspects the next track.