JPH0478036A - Disk defect coordinate fetching system - Google Patents

Abstract

PURPOSE:To save memory capacity by storing the coordinates of the angle of circumference and the radial position of a defective signal in a RAM, and displaying a defect on a map corresponding to the coordinates by the processing of a microprocessor. CONSTITUTION:The defective signal Pd is inputted to a beginning point.end point detection circuit 8, and an angle pulse a rotary encoder 10 installed at a rotating mechanism outputs is inputted, and by making these a trigger, a beginning point pulse and an end point pulse for the beginning point and the end point of the defective signal Pd are generated, and the coordinates of the angle of circumference and the radial position for the beginning point and the end point are stored in the RAMs 14a, 14b. Then, by processing these by the microprocessor 9, the continuous defect is map-displayed in a continuous state. Thus, the coordinates of all the points of the continuous defect are not necessitated, and the memory capacity is saved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application] The present invention relates to a system for capturing coordinate data indicating the location of a disk defect.

[Prior Art] Information recording media such as magnetic disks, optical disks, or magneto-optical disks are inspected by a disk defect inspection device because if there are defects on the surface, the quality of data recording performance deteriorates. An optical method using a laser is used for inspection.

2(a), (b), and (C), an overview of disk defects, a basic optical system of a laser disk defect inspection apparatus, and a method of measuring defect data will be explained. Figure (a
), ■ is each of the above disks, and on its surface, isolated defects (A), continuous line defects (0), or planar surface defects (C) are randomly distributed. . In Figure (b), a disk 1 is mounted on a spindle 2 and rotates, and a laser beam from light #3 is projected onto the disk 1 to form a spot Sp on the surface of the disk.

The spot Sp moves in the direction of the radius R and scans the surface in a spiral manner, and if there is a defect, scattered light is generated. The scattered light is condensed by a condensing lens 4 and received by a light receiver 5 consisting of a photoelectric converter, various defects are detected, and defect signals are taken into the microprocessor. Note that the above optical system is a basic one, and various optical systems are used in combination to efficiently detect various defects, and the light reception signal of the photoreceiver is identified using various thresholds. The size of the defect is taken as defect data.

The defect data obtained above is appropriately aggregated and displayed on a display as a map showing the location of defects for convenient observation and evaluation.

For map display, the circumferential angle θ and radius R of the disk are divided into minute Δθ and Δr, respectively, and divided into unit cells ΔS, as shown in FIG. Here, the division of Δθ is performed by an angle pulse obtained from a rotary encoder of the disk rotation mechanism, and the division of Δr is performed by the movement of the spot Sp with respect to the rotation of the disk. Therefore,
The coordinate of ΔS for the spot Sp is obtained by counting the angle pulse and the number of revolutions, and the coordinate of ΔS at the time when the defect signal is input is stored in the memory and used for map display.

[Problem to be solved] Recently, as the recording density of disks has improved, the allowable defect size has become smaller and smaller, and the above unit cell ΔS needs to be made even smaller to accommodate this. It is. For example, in the past, when Δθ and Δr were set to ~0.5 mm, ΔS was approximately 0°25 mm2, but by setting Δθ and Δr to 1/50 or less, ΔS was reduced to 1/2500 or less. It may be reduced. As described above, defects are stored in the memory for each coordinate of the unit cell ΔS, so when ΔS is reduced, it is necessary to increase the memory capacity by more than 2500 times compared to the above example.

On the other hand, in the case of optical disks, inspection is performed even when groups (grooves) are formed, and crushed groups are considered defects. Increasingly large amounts of memory capacity are required. On the other hand, it is desirable to save memory capacity by compressing the defect data for each unit cell ΔS as much as possible so as not to interfere with map display.

The present invention has been made in view of the above, and it is an object of the present invention to provide a method for importing defect coordinates in a disk defect inspection device that does not interfere with map display of defect data and can save memory capacity.

[Means for Solving the Problems] This invention detects the circumferential angle and radial position of a defect signal obtained by an inspection optical system for a defect on a disk by using an angular pulse output from a rotary encoder. This is a disk defect coordinate acquisition method in a disk defect inspection apparatus in which the coordinates of the defect are stored in the RAM and the defects are displayed on a map corresponding to the coordinates through processing by a microprocessor. By using the start point pulse and the end point pulse for the start point and end point of the defect, the circumferential angle and radial position coordinates of the disk for the start point and end point are stored in the RAM, and the processing of the micro processor is used to map successive defects in a continuous state. do.

The above-mentioned start point pulse and end point pulse are generated by inputting a defective image to a start point/end point detection circuit consisting of two flip-flops, an exclusive OR circuit, and an AND circuit, and using the angle pulse as a trigger.

[In the disk defect coordinate capture method described above, the start point pulse and end point pulse for the start point and end point of the defect are used to
The coordinates of the circumferential angle and radial position relative to the start point and end point are R
This is stored in the AM and processed by a microprocessor to display a continuous map of consecutive defects, which requires the coordinates of all points of consecutive defects, which requires a large amount of memory. You can save money. These start point pulses and end point pulses are easily generated by inputting a defect signal to the start point/end point detection circuit and using the angle pulse from the rotary encoder as a trigger.

[Example 1] Figures 1 (a), (b), and (c) show the block configuration of a disk defect inspection apparatus, the start point/end point detection circuit, and its operation in an embodiment of the disk defect coordinate capture method according to the present invention. A time chart of signal waveforms to be explained is shown. In FIG. 3A, a light reception signal of scattered light due to a defect is outputted from a light receiver 5, appropriately amplified by an amplifier 6, and inputted to a + terminal of a comparator 7. On the other hand, an appropriate digital threshold value [SL] supplied from the microprocessor (MPU) 9 is given to one terminal as an analog quantity SL by the D/A converter 9a, and a defect is identified. The defect signal Pd is input to the start point/end point detection circuit 8.

On the other hand, input the angle pulse [Δθ] output from the rotary encoder (ENC) +o installed in the rotating mechanism, and use this as a trigger to generate the start point pulse and end point pulse for the start and end points of the defect signal. , these are input to the defect number counter 13 and counted. This count number is added to RAM14a and +4b as an address signal.

On the other hand, the angle pulse [Δθ] is input to the θ counter 12a to change the rotation angle data [θ] of the disk, and the E
[O] indicates the reference point of the rotation angle O output from SCIO.
[°] signal is counted by the R color/return 12b and the radial position data [R] is changed. Send the start point pulse and end point pulse with the enable (EN) signal, and set the data [0 and [
R is stored in the addresses of the RAMs 14a and 14b with the above number of addresses, respectively. The stored data [θ] and [R] are processed by the MPU 9 and output to the display 9b, where they are displayed as a map corresponding to the coordinates of the defect.

If the defects are consecutive, they are listed as consecutive.

The start point/end point detection circuit 8 and its operation will be explained with reference to FIGS. 1(b) and 1(c). The start point/end point detection circuit 8 shown in FIG.
)8b is connected as shown in the figure, and both outputs Ql, Q
2 is input to the AND circuit 8d via the exclusive OR circuit 8C. Also, (FFI) 8a.

An angle pulse [Δθ] is applied to the (FF2) 8b and the AND circuit 8d. On the other hand, in Figure (C), the light reception signal of the light receiver 5 is shown as (A), and this is identified by the threshold port SL] in the comparator 7 and the defect signal Pd is changed. When the defect signal Pd (FFI) is input manually to the D terminal of 8a, Ql becomes "1" due to [Δθ], and this becomes (FFI).
2) 5 is applied to the D terminal of 8b. At this point, Q2 is "O", so when the exclusive OR circuit 8C outputs "1" or when Q2 becomes "1" due to the next [Δθ], the output of the exclusive OR circuit 8c becomes "0", The output during this period is the starting point signal ps.When the defect signal Pd ends, Ql is “
However, since Q2 is "1" for one [Δθ], the end point signal pe is output during that time.Here,
If the defect signal is short as shown in (b) of Figure (b) and is equal to or less than [Δθ], the start point signal ps and end point signal pe are continuous as shown in the figure, so these should be separated. or is necessary. Therefore, the AND circuit 8d separates them by ANDing these and [80] to generate the start point or end point pulse pc.

The above defect coordinate acquisition method is for a defect signal identified by a single threshold value SL, or in an actual disk defect inspection apparatus, various optical systems are combined as described above, and the threshold value SL is The size of the defect is detected in stages, and the coordinate acquisition method described in L is applied to each defect signal obtained by these optical systems or multiple threshold values, and the obtained defect data is aggregated by the MPU. can be displayed on one map.

[Effects of the Invention] As is clear from the above explanation, in the disk defect coordinate import method according to the present invention, the circumferential angle and radial position coordinates for the starting point and ending point of the defect are stored in the RAM, and these are stored by the microprocessor. By processing, continuous defects can be displayed as a map in a continuous state, and the memory capacity required for determining the coordinates of all points of continuous defects can be greatly reduced, and it is used in information recording media. The effects obtained when applied to a defect inspection device for various types of high-density disks are significant.

[Brief explanation of drawings]

FIGS. 1(a), (b), and (C) show an embodiment of the disk defect coordinate capturing method according to the present invention. FIG. 2(a) is a configuration diagram of the start point/end point detection circuit and a time chart of signal waveforms for its operation. (b) and (C) are explanatory diagrams of defects on a disc, a basic configuration diagram of an optical system of a disc inspection apparatus, and an explanatory diagram of a method of displaying a map of defect data.

Claims (2)

[Claims] (1) In response to a defect signal for a defect on the disk to be inspected obtained by the inspection optical system, the coordinates of the circumferential angle and radial position for the defect signal are stored in the RAM by the angle pulse output from the rotary encoder, and In a disk defect inspection device that displays the defect on a map corresponding to the coordinates through processing by a processor, the circumferential angle and radius of the disk relative to the start point and end point are determined by the start point pulse and end point pulse for the start point and end point of the defect. A disk defect coordinate importing method characterized in that position coordinates are stored in the RAM, and continuous defects are displayed as a map in a continuous state through processing by the microprocessor. (2) The above defect signal is connected to two flip-flops, exclusive O
2. The disk defect coordinate acquisition method according to claim 1, wherein the input is input to a start point/end point detection circuit comprising an R circuit and an AND circuit, and the start point pulse and end point pulse are generated using the angle pulse as a trigger.