JPH034149A - Device for inspecting disc surface - Google Patents

Abstract

PURPOSE:To simultaneously and independently detect a pit and a flaw by providing a mirror having a hole at a position corresponding to the position of the optical axis of the reflected light of a laser beam. CONSTITUTION:The surface of a disk 1 is scanned with the laser beam from a laser irradiation device 2. Next, the 1st photoelectric conversion circuit, which receives the reflected light of the laser beam, receives the reflected light passing through the mirror 4 having the hole 3 at the position corresponding to the position of the optical axis L and the hole 3 and generates a corresponding electrical signal. Then, the 2nd photoelectric conversion circuit receives the reflected light by the mirror 4 and generates the corresponding electrical signal. The 1st and the 2nd detection circuits compare the signals from the 1st and the 2nd conversion circuits with specified level and generate detection signals respectively. Furthermore, the 3rd detection (continuity decision) circuit 17 detects that the detection signals from the 2nd detection circuit are continuously generated for a fixed time or equal to or above a fixed number. Then, the signal from the 1st detection circuit and the signal from the 3rd detection circuit are obtained as a pit-state fault detection signal and a flaw detection signal respectively.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a disk surface inspection device, and in detail,
Inspection equipment that inspects defects on the surface of disks such as glass, which can particularly detect minute, relatively deep, concave defects (hereinafter referred to as bits) and linear defects. Regarding equipment.

[Prior Art] In magnetic storage devices, f-conductor Ueno 1, etc., disks made of glass, Noricon, etc. are used as base materials for information recording media or as semiconductor materials. If there are defects on the surface, the quality of the product will deteriorate, so these can be detected using a disk surface inspection device. iIh
and then used.

There are 8 NA types of defects on the surface of the disk, but they can be broadly classified as defects such as scratches (in this Specification-F, flaws refer to flaws in minute recesses that have penetrated into the inside of the disk). (Used in the concept of larger flaws excluding pits), pits, holes, and even those formed on the surface such as foreign matter such as attached dust or dirt. Of these, defects such as scratches and pits are defects in the material itself and are difficult to remove, but attached foreign matter can be removed by cleaning. Furthermore, depending on the condition and number of pits and flaws, it is possible to use the product as a product if countermeasures are taken.

For this reason, it is necessary to manage the types of defects. So, disk surface +! In the 11th inspection device, it is particularly necessary to determine whether a detected defect is a flaw or a crack or a splinter.

[Problem to be solved] In order to determine whether a detected defect is a defect or a pit, a disk surface inspection device runs across the disk surface and uses an optical sensor or the like to check the state of the defect using an electronic signal generator. Inspections are carried out by converting the data into a 3D image and storing it for one revolution or several revolutions, for example. Therefore, the data fit becomes very large. Furthermore, processing the data to determine whether it is a pit or flaw and managing the number and position thereof requires a lot of time.

The present invention solves the problems of the prior art, and aims to provide a disk surface inspection device that can simultaneously and independently detect pits and flaws.

[F stage for solving the problem] The configuration of the disk surface inspection apparatus of the present invention to achieve such an object is as follows: A running mechanism that scans the surface with a mirror, a mirror that receives the reflected light of the laser beam and has a hole at a position corresponding to the position of the optical axis, and a mirror that receives the reflected light that passes through the hole and generates an electrical signal corresponding to it. a first photoelectric conversion circuit that receives reflected light from the mirror and generates an electrical signal corresponding to the reflected light from the mirror;
a first detection circuit that directly or amplifies the signal from the first photoelectric conversion circuit and compares it with a predetermined level to generate a detection signal; and a signal from the second photoelectric conversion circuit. a second detection circuit that generates a detection signal by directly or amplifying it and comparing it with a predetermined level, and a detection signal of this second detection circuit that is continuously generated for a certain period of time or in a certain quantity a third detection circuit for detecting the presence of a pit-like defect;
The signal from the third detection circuit is obtained as a flaw detection signal.

[Effect] By the way, when a laser beam is irradiated onto a light-reflecting surface such as a glass disk, the light reflected by deep and small concave defects such as pits is generally scattered less and is not dispersed much from the optical axis. Reflected light occurs. On the other hand, reflected light from a somewhat large flaw, a long flaw, a shallow flaw, etc. has a large scattering width, and generates reflected light that is dispersed far from the optical axis.

Therefore, as in the above configuration, a mirror with a hole is provided at a position corresponding to the position of the optical axis, and a detector detects reflected light obtained through the hole, and a detector detects reflected light from the mirror. Furthermore, by providing a detection circuit on the side that detects the reflected light of the mirror to identify whether or not the reflected light can be obtained continuously, the detector 2) obtained from one of the detectors can be The detection signal obtained from the other detection circuit can be used as the flaw signal.

As a result, if a single disk surface inspection device can detect both focus and flaws at the same time, and stores this information according to position information, it is possible to use a device with a large memory capacity as in the past. Moreover, since pits and flaws are sorted and collected, subsequent data processing is simplified, IM can be performed in a short time, and inspection efficiency can be improved.

[Embodiment] FIG. 1 is a block diagram of an embodiment of a disk surface inspection apparatus according to the present invention.

In the figure, reference numeral 20 denotes a detection optical detection system of the disk surface inspection apparatus, which irradiates the surface of the glass disk 1 with a laser beam T from a laser irradiation device Wt2 at a relatively large incident angle Ol, and its reflected light A mirror 4 tilted at a low angle θ2 with a hole 3 in the center thereof is provided so that the hole 3 is located corresponding to the position of the optical axis.

Therefore, the scattered light Ro (zero-order term reflected light) near the optical axis of the reflected light passes through the hole 3 and is transmitted to the bin photodiode.
The light is received by the light receiving element 5 (a specific example of the first photoelectric conversion circuit) composed of - and detected.

On the other hand, the scattered light Rr (reflected light of terms after the first order) of the reflected light irradiated outward from the periphery of the hole 3 of the mirror 4 with the hole 3 is condensed by the condensing lens 6 and converted into a photomultiplier, etc. The light is irradiated onto the light receiver 7 (a specific example of the second photoelectric conversion circuit) and detected thereby.

Note that the glass disk 1 is used for image processing 'A position 1, which will be described later.
The control signal 18a from 8'V rotates the motor connected to the spindle of the glass disk l, and as a result, scanning for one track is performed by the laser beam T, and the laser irradiation device 2 adjusts the radius of the glass disk l. By moving towards the center along Not particularly shown.

Here, the level of the scattered light R, increases when there are pits on the surface of the glass disk 1, and the level of the scattered light R1 increases.
The level becomes stronger when there are flaws on the surface of the glass disk 1.

Now, the scattered light RO received and detected by the light receiving element 5 becomes an electric signal, which is amplified by the amplifier circuit 1O and inputted to the comparator (COM) 11. The comparator 11 inputs a reference voltage vl that can be adjusted and set as a comparison standard to the other human power, for example, to an image processing device 18 (described later).
, and a signal exceeding this slice level v1 is output as a pit detection signal. This detection signal is then sent to the game 15a.

Similarly, the scattered light R1 received and detected by the light receiver 7 becomes an electric signal, is amplified by the amplifier circuit 13, and is input to the comparator (COM) 14G. The comparator 14 has an adjustment setting r
Similarly, the reference voltage v2, which can be used as a slice level, is received from the image processing device 18 as a slice level.
A signal exceeding 2 is output as a flaw (other than pit) detection signal.

This detection signal is then sent to the gate 15b.

Reference numeral 16 denotes a rotation synchronization clock generation circuit, which generates a clock synchronized with a rotation synchronization signal obtained from the rotation drive device of the glass disk 1, and transmits the clock to the gates 15a and 15b.
This clock is added as a gate signal to
The signal is sent to the continuity determination circuit 17 and the image processing device 18 as a position signal.

Therefore, in response to a clock synchronized with the rotation synchronization signal,
A 1-bit pit detection signal corresponding to the clock is obtained at the output of the gate 15a, and a 1-bit flaw detection signal corresponding to the clock is obtained at the output of the gate 15b.

The pit detection signal output of game) 15a is output from the image processing device 1.
8, and the flaw detection signal output from the gate 15b is manually input to a continuity determination circuit 17, which is constituted by a shift register or the like. The continuity determination circuit 17 receives the detection signal obtained from the gate 15b as a 1-bit signal in response to the clock signal from the rotation synchronization clock generation circuit 16, and sends this signal to the shift register in accordance with the clock. to shift sequentially and memorize it. Then, the continuity of the flaw detection signal is determined by decoding the value of the "l" pit from "l" to "O" using a decoder that receives and decodes each digit of the shift register. , when "0" is input to the shift register, it is output to the image processing device 18 as flaw length information.

The image processing device 18 receives the pit detection signal and the flaw length information, counts the clock of the rotation synchronization clock generation circuit 16, receives the rotating base position signal 19 of the glass disk l, and extracts the glass disk from them. The position information of 1 is calculated, and the received bit and flaw length information are recorded together with the position t and 9X. Then, when the position of a pin or gutter overlaps the position of a flaw, it is determined whether it is a flaw or a bit based on the length, and the data of the bit information and the flaw information is corrected. In addition, if a flaw with almost no length occurs in the above data other than the bit position, for example, ■ When a length detection signal of several pittle bits is obtained, it can be considered as a flaw. Instead, treat it as a foreign object, exclude it from the data, and manage that data as a foreign object.

Thereafter, the flaws and bits are displayed on the display, for example, in different colors, and in the case of flaws, the length thereof is also displayed as a map according to the position information.

Salt 1 - As explained above, in the example, the photoreceptor r.

Although the signals from the light receiver are amplified by an amplifier and compared by a comparator, it is of course possible to directly compare the signals depending on the output level of the light receiving element r or the light receiver.

In the embodiment, a continuity judgment circuit is provided to judge the continuity of flaws, but this may be any circuit that can distinguish between bits and flaws, and it is not necessarily necessary to output data including the length. do not have. Therefore, this time is one minute for a detection circuit that generates a flaw detection signal by detecting whether or not there is quantitative continuity between the detection signal from the flaw detection circuit and s'P-.

Further, although the embodiments show examples of glass disks, the present invention is not limited to glass disks (any reflective disk can be applied).

[Effects of the Invention] As can be understood from the above description, the present invention provides a mirror with a hole at a position corresponding to the position of the optical axis, and a detector that detects reflected light obtained through the hole. By providing a detector for detecting the reflected light of the mirror, and further providing a detection circuit on the side that detects the reflected light of the mirror for determining whether or not the reflected light is continuously obtained,--
The detection signal obtained from one of the detectors can be used as a bit detection signal, and the detection signal obtained from the other detection circuit can be used as a flaw signal.

As a result, if a single disk surface inspection device can detect bits and flaws at the same time and store this information according to position information, it will no longer be necessary to use a large memory capacity h as in the past. In addition, since pits and defects are classified and collected, subsequent data processing is simplified, inspection can be completed in a short time, and inspection efficiency can be improved.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an embodiment of a disk surface inspection apparatus according to the present invention. l...Glass disk, 2...Laser irradiation device, 3
... hole, 4... mirror 4.5... light receiving element r, 6.
...Condensing lens, 7... Light receiver, 10.12... Amplifying circuit, 11.13... Converter, 16... Rotation synchronization clock generation circuit, 17... Continuity determination circuit, 1
8... Image processing device, 20... Optical detection system of disk surface inspection device.

Claims (1)

[Claims] (1) A laser beam irradiation device that irradiates the surface of the disk with a laser beam; a scanning mechanism that scans the surface with the laser beam; a mirror with a hole; a first photoelectric conversion circuit that receives the reflected light that has passed through the hole and generates an electric signal corresponding thereto; and a first photoelectric conversion circuit that receives the reflected light from the mirror and generates an electric signal corresponding thereto. Second to do
A first detection circuit that directly or amplifies the signal from the first photoelectric conversion circuit and compares it with a predetermined level to generate a detection signal, and a signal from the second photoelectric conversion circuit. a second detection circuit that generates a detection signal by directly or amplifying it and comparing it with a predetermined level; and a detection signal of this second detection circuit that is continuously generated for a certain period of time or a certain number of times. and a third detection circuit for detecting the presence of defects, the signal of the first detection circuit is obtained as a pit-like defect detection signal, and the signal of the third detection circuit is obtained as a flaw detection signal. Disc surface inspection equipment.