JP5891195B2 - Optical inspection apparatus and optical inspection method for magnetic media - Google Patents

Description

  The present invention relates to an optical inspection apparatus and an optical inspection method for magnetic media.

  As a substrate for magnetic media (magnetic disk), an aluminum (Al) substrate or a glass substrate is used. Depending on the application, crystallized glass (SX) or amorphous glass (MEL) is used as the glass substrate, and in each type of glass, a plurality of types of glass having different components are used.

  In the glass substrate, a minute dent (pit) defect or a minute protrusion (bit) defect may occur on the surface of the substrate during the processing step. A glass substrate on which such a minute defect exists is highly likely to be rejected as a defective product in the final inspection process. Therefore, it is desirable to remove the glass substrate having a high probability of being defective as described above from the line in the initial process of the production line in order to maintain a high production yield.

  There are various sizes of glass substrates or aluminum substrates and magnetic disks according to applications, and general sizes include a magnetic disk for mobile use with an outer diameter of 1.8 inches, a magnetic disk for desktop use with 2.5 inches, and 3. There are magnetic disks for 5-inch servers. Furthermore, there are various types of inner diameters. For example, a disk with an outer diameter of 2.5 inches has an inner diameter of 20 mm for a desktop and a disk with a diameter of 25 mm for a server. As the use of hard disks expands, such as the presence of inch disks and 3.5 inch disks, the size of magnetic media has become more complex and diverse.

  Under such circumstances, regardless of the inspection method, an optical inspection apparatus for magnetic media (magnetic disk) is required to have a function corresponding to various disk sizes. As a method of fixing an inspection target disk in an optical inspection apparatus, an apparatus for optically inspecting a defect on a disk surface as described in Patent Document 1, for example, as described in Patent Document 2 A general method is to clamp the center hole of the disk using a dedicated hub and rotate the disk by a spindle. In addition, a method has been adopted in which a dedicated hub is prepared for each inner diameter of the disk, and the hub size is exchanged according to the size of the disk to be inspected, so that one apparatus can cope with a plurality of disk sizes.

JP 2011-76669 A JP 2011-192368 A

  In an optical inspection apparatus for magnetic media corresponding to magnetic disks of various sizes, it is necessary to prepare a dedicated hub corresponding to the size and to change the inspection area in the radial direction of the disk according to the disk. is there. This inspection area differs depending on the size of the disk and may overlap. As an example, in a disk having an outer diameter of 2.5 inches and an inner diameter of 20 mm and a disk having an inner diameter of 25 mm, an inspection area overlap of about 2.5 mm occurs on the inner diameter side. This overlap causes a collision between the device inspection mechanism and the hub. In an apparatus for optically inspecting a disk surface defect as described in Patent Document 1, an inspection mechanism in which a lens or a mirror that collects reflected light from the disk surface relatively moves on the disk surface to be inspected. As a risk of collision with the hub.

  In inspections in the magnetic disk test process, there are many cases where the area close to the inner diameter of the magnetic disk is set as the inspection area. In such operations, the size of the hub mounted on the apparatus and the setting of the inspection area in the apparatus software, etc. There is a risk that the above-described inspection mechanism and the hub collide when the mismatch occurs.

  Patent Document 1 does not describe preventing the collision between the inspection mechanism and the hub. Also, Patent Document 2 does not describe preventing the upper end portion of the hub protruding beyond the upper surface of the disk from colliding with the inspection mechanism when the disk is chucked.

  As a mechanism for preventing this collision, a method such as using a light shielding sensor between the spindle carriage and the inspection mechanism can be considered, but a mechanism for detecting the inspection mechanism that moves relatively close to the inner diameter of the disk (the outer diameter of the hub). Therefore, it is necessary to make the operation accuracy of the sensor itself and the position accuracy of the sensor extremely high, and high responsiveness is also required for the operation of stopping the spindle carriage. Security problems, control technology problems, and cost problems occur. Furthermore, as a mechanism to prevent the collision between the inspection mechanism and the hub simply and reliably, a method using a mechanical stopper between the spindle carriage and the inspection mechanism is conceivable. However, in a device in which the hub diameter can be changed by replacing the hub. When changing the size of the disk to be inspected, the hub may be replaced with a mechanical stopper, and in such a device, a human error such as forgetting to replace the mechanical stopper may occur. is there.

  The present invention solves the above-described problems of the prior art and reliably prevents the collision between the inspection mechanism and the hub even when the hub for clamping the disc is replaced according to the type of the disc. It is an object of the present invention to provide an optical inspection apparatus for magnetic media that makes it possible to achieve this.

  In order to solve the above problems, in the present invention, an optical inspection apparatus for magnetic media includes a disk delivery unit that delivers a disk that is a magnetic medium to be inspected, a disk inspection unit that optically inspects a disk, and a disk A disk transport unit that fits into the hole in the center of the disk and mounts the disk, mounts the disk on the hub and moves between the disk delivery section and the disk inspection section, and the disk transport unit is the hub Detecting means for detecting a size of a portion of the hub of the hub mounted with the disk, which is engaged with a hole in the central portion of the hub in the middle of moving from the disk delivery section to the disk inspection section with the disk mounted on the disk, and the detecting means If the size of the part of the hub that is detected in step 1 is different from the preset size, the disc is transported. It was constructed and a control means for stopping the movement of the knitting.

  In order to solve the above problems, in the present invention, in the disk delivery section, the hole in the center of the disk, which is the magnetic medium to be inspected, is fitted to the tip of the hub and mounted on the hub. The mounted hub is transported to a disk inspection unit that optically inspects the disk. In the optical inspection method for magnetic media in which the disk is optically inspected by this disk inspection unit, the hub on which the disk is mounted is transported to the disk inspection unit. In the middle of the process, the size of the part that fits into the hole in the center part of the hub disk is detected, and the size of the part that fits into the hole in the center part of the hub disk is preset. The transport of the hub is stopped when it is different from the size.

  According to the present invention, in the optical inspection apparatus for magnetic media, when the spindle carriage that moves between the inspection mechanism and the disk supply / discharge position moves toward the inspection mechanism, the inspection target disk mounted on the spindle carriage It is now possible to prevent the replaceable hub from interfering with the inspection mechanism and destroying the inspection mechanism depending on the size of the machine.

1 is a front block diagram showing a schematic configuration of an optical inspection apparatus for magnetic media according to an embodiment of the present invention. 1 is a front block diagram showing a schematic configuration of an optical inspection apparatus for magnetic media according to an embodiment of the present invention. It is a front block diagram which shows the structure of the outline of the optical inspection unit which concerns on the Example of this invention. It is a block diagram of the front which shows the outline structure of the low angle detection optical system of the front side inspection optical system of the optical inspection unit which concerns on the Example of this invention. It is a front view of the detection surface of the regular reflection light detector of the optical inspection unit which concerns on the Example of this invention. It is a block diagram of the front which shows the outline structure of the high angle detection optical system of the front side inspection optical system of the optical inspection unit which concerns on the Example of this invention. It is a top view of a magnetic disk. 1 is a block diagram of a front side of an optical inspection apparatus for magnetic media according to an embodiment of the present invention, showing a state in which a front portion of a disk being transported by a spindle carriage has reached a laser displacement meter. FIG. 1 is a block diagram of a front side of an optical inspection apparatus for magnetic media according to an embodiment of the present invention, showing a state in which a tip portion of a hub being conveyed by a spindle carriage is approaching a laser displacement meter. FIG. 1 is a block diagram of a front side of an optical inspection apparatus for magnetic media according to an embodiment of the present invention, showing a state in which a rear portion of a disk being conveyed by a spindle carriage reaches a laser displacement meter. FIG. It is a front view of a spindle carriage showing a case where a range where H is detected in a height detected by a laser displacement meter 1050 is narrow in an optical inspection apparatus for magnetic media according to an embodiment of the present invention. FIG. 6 is a front view of a spindle carriage showing a case where a range in which H is detected in a height detected by a laser displacement meter 1050 in a magnetic media optical inspection apparatus according to an embodiment of the present invention is relatively wide. It is a front view of a spindle carriage showing a case where the range in which H is detected in the height detected by the laser displacement meter 1050 is wider in the optical inspection apparatus for magnetic media according to the embodiment of the present invention. 1 is a block diagram of a front side of an optical inspection apparatus for magnetic media according to an embodiment of the present invention, showing a state where a spindle carriage has reached an optical inspection unit.

In the present invention, in the optical inspection apparatus for magnetic media, the size of the hub is detected by the laser displacement meter while the spindle carriage moving between the inspection mechanism and the disk supply / discharge position is moving toward the inspection mechanism. Then, the diameter information of the hub detected by the laser displacement meter is collated with the information of the inspection area set in the inspection apparatus, and when both coincide, the spindle carriage is moved to the inspection mechanism side as it is. If they do not match, stop the spindle carriage movement and return it to the start position, replace the hub with an appropriate one, adjust the inspection mechanism, and then move the spindle carriage to the inspection mechanism side again. Can be prevented from interfering with the inspection mechanism and destroying the inspection mechanism.
Embodiments of the present invention will be described below with reference to the drawings.

  As an example of an optical inspection apparatus for magnetic media, an example of an optical disk inspection apparatus that optically inspects scratches or adhering foreign matter on both sides of the disk will be described.

FIG. 1A is a front view showing a schematic configuration of an optical inspection apparatus 1000 for magnetic media, and FIG. 1B is a plan view thereof.
An optical inspection apparatus 1000 for magnetic media includes an optical inspection unit 1200 including a delivery unit 1100 for delivering the disk 1 and an optical inspection unit 1210 for optically inspecting both sides of the disk 1 simultaneously, and an overall control unit 1300. In the meantime, the spindle carriage 1004 reciprocally moves on the disk 1 mounted on the hub 1001 between them.

  The spindle carriage 1004 is mounted with a hub 1001 driven by a spindle motor (not shown), and a hole 2 in the center portion of the disk 1 is fitted to the tip portion 1002 of the hub 1001 and chucked by a chuck mechanism (not shown). Hold the disc 1. In a state where the disk 1 is held, the tip end portion 1002 of the hub 1001 protrudes upward from the upper surface of the disk 1.

  The spindle carriage 1004 is engaged with a ball screw 1005 and a guide shaft 1006. The ball screw 1005 is rotationally driven by a stepping motor 1003, and the amount of rotation is measured by an encoder 1008. The guide shaft 1006, the stepping motor 1003, and the encoder 1008 are fixed to the base plate 1011 with support columns 1009 and 1010, respectively.

  In the delivery unit 1100, an uninspected disc is taken out from a cassette (not shown) by a handling unit (not shown), and the center of the disc 1 is placed on the front end portion 1002 of the hub 1001 of the spindle carriage 1004 waiting in the delivery unit 1100. The disk 1 is held by fitting the hole 2 in the part.

  With the disk 1 held by the hub 1001, the spindle carriage 1004 moves along the guide shaft 1006 toward the optical inspection unit 1200 when the ball screw 1005 rotated by the stepping motor 1003 rotates.

  As shown in FIG. 2A, the optical inspection unit 1210 of the optical inspection unit 1200 includes a front-side inspection optical system 1211 that inspects the front-side (upper) surface of the disk 1 with optical technology, and the back side (lower-side) of the disk 1. And a back side inspection optical system 1212 for optically inspecting the surface of the disk 1 and inspecting both surfaces of the disk 1 simultaneously.

  The front-side inspection optical system 1211 includes an illuminating unit 100 that irradiates illumination light on the surface side of the disk 1, and a low-angle direction (the angle formed with the normal direction of the surface of the disk 1 is from the surface side of the disk 1 irradiated with the illumination light). Low angle detection optical system 200 that collects and detects light that is regularly reflected / scattered in a small direction (high elevation angle direction), and an angle between the surface side of the disk 1 and a high angle direction (normal direction of the surface of the disk 1). A high angle detection optical system 300 that collects and detects light scattered in a large direction (low elevation angle direction) is provided.

  The back side inspection optical system 1212 converts the path of the illumination light to irradiate the back surface of the disk 1 with the illumination unit 100 ′ that irradiates illumination light on the back side of the disk 1 and the illumination light emitted from the illumination unit 100 ′. Mirror 101 collects the light that is regularly reflected and scattered in the low-angle direction (the direction in which the angle normal to the surface of the disk 1 is small: the high elevation angle direction) from the back side of the disk 1 irradiated with the illumination light. The low-angle detection optical system 200 ′ to detect, collects and detects light scattered from the back side of the disk 1 in a high angle direction (a direction with a large angle with the normal direction of the surface of the disk 1: a low elevation angle direction). A high angle detection optical system 300 'is provided.

  The optical inspection unit 1210 further detects the respective analog detections output by detecting the regular reflection / scattered light from the disc 1 by the low angle detection optical systems 200 and 200 ′ and the high angle detection optical systems 300 and 300 ′, respectively. A / D converter 400 that amplifies the signal and converts it into a digital signal (A / D conversion), processing unit 500 that receives and processes the signal from each detector converted by A / D converter 400, and processing unit Input / output means 600 for inputting 500 processing conditions and outputting the processing results is provided. The entire optical inspection unit 1210 is controlled by the overall control unit 1300.

The height of the front-side inspection optical system 1211 is adjusted by the vertical drive device 1213 according to the type of the disk 1 to be inspected.
The illumination means 100 and 100 ′ include a laser light source that outputs a laser having a desired wavelength.

  Since the low-angle detection optical systems 200 and 200 ′ and the high-angle detection optical systems 300 and 300 ′ have basically the same configuration, the following description is based on the front-side inspection optical system 1211 that inspects the surface of the disk 1. The low angle detection optical system 200 and the high angle detection optical system 300 will be described.

  The low-angle detection optical system 200 includes reflected / reflected light that is irradiated by the illuminating unit 100 and includes specularly reflected light that is reflected / scattered on the surface of the disk 1 and travels in the low angle direction (high elevation angle direction) among the directions indicated by the dotted lines. An optical system for detecting scattered light.

  As shown in FIG. 2B, the low-angle detection optical system 200 reflects the specularly reflected light that travels in the low-angle direction from the surface of the disk 1, and the scattered light around the specularly reflected light that is not reflected by the mirror 201. A Fresnel lens 202 that plays the role of a converging objective lens, an objective lens 203 that condenses the specularly reflected light reflected by the mirror 201, and a converging lens that converges the specularly reflected light from the disk 1 that is condensed by the objective lens 203. 204, a pinhole plate 205 that has a pinhole for passing the specularly reflected light focused at the convergence point of the specularly reflected light by the converging lens 204 and shields stray light other than the specularly reflected light, and this pinhole plate 205 Light reflected by a specular reflection detector 206 configured to detect specular reflection light that has passed through the pinhole and light condensed by the Fresnel lens 202 (dis A converging lens 207 for converging (the scattered light around the specularly reflected light from 1), and a pin hole located at the converging point of the converging lens 207 for passing the converged light and blocking the unconverged light A hall plate 208 and a low-angle detector 209 that detects light passing through the pinhole plate 208 are provided.

  Here, as shown in FIG. 2C, the regular reflection light detector 206 is configured by a four-divided sensor in which the detection surface is divided into four detection elements 2061 to 2064. However, the regular reflection light detector 206 is not limited to a four-divided sensor, and may be a six-divided sensor or an eight-divided sensor. In FIG. 2C, the detection element is shown as a rectangle, but a quadrant sensor in which a circle is divided into four may be used.

  As shown in FIG. 2D, the high-angle detection optical system 300 collects scattered light emitted from the illumination unit 100 and reflected and scattered from the surface of the disk 1 in the high angle direction (low elevation angle direction). A Fresnel lens 301 serving as an objective lens, a converging lens 302 for converging the light collected by the Fresnel lens 301, and a pinhole for passing the converged light located at the converging point of the converging lens 302. A pinhole plate 303 that shields unfocused light and a high-angle detector 304 that detects light that has passed through the pinhole plate 303 are provided.

  In a state where the disk 1 is rotated by driving a spindle motor (not shown) by the overall control unit 1300 and rotating the hub 1001, the overall control unit 1300 drives the stepping motor 1003 to move the spindle carriage 1004 at a constant speed. Then, both sides of the disk 1 are inspected spirally by moving in the radial direction of the disk 1. The position and moving speed of the spindle carriage 1004 are controlled by detecting the rotation of the ball screw 1005 with the encoder 1008.

  In this inspection, analog signals output from the detectors 206, 209, and 304 that have detected the light reflected and scattered by the surface of the disk 1 are respectively output from the A / D converters 401 to 403 of the A / D converter 400. Amplified, A / D converted, and input to the processing unit 500. Similarly, the analog signals output from the low angle detection optical system 200 ′ and the high angle detection optical system 300 ′ that detect the light reflected and scattered by the back surface of the disk 1 are respectively A / D converted by the A / D converter 400. Amplified by the converters 401 ′ to 403 ′, A / D converted, and input to the processing unit 500.

  The processing unit 500 processes the signals amplified and A / D converted by the A / D converters 401 to 403 and 401 ′ to 403 ′, detects defects, classifies them by defect type, and obtains the obtained defects. The quality of the disk 1 is determined based on the number and distribution of defects for each species.

  The disk 1 has a donut-shaped planar shape as shown in FIG. 3, and the thickness, outer diameter, and inner diameter of the hole 2 differ depending on the type, and the diameter of the hub 1001 of the spindle carriage 1004 that conveys the disk 1 accordingly. The diameter of the tip portion 1002 is different.

  Information on the type of the disk 1 is input from an input unit (not shown) of the overall control unit 1300 and is controlled by the overall control unit 1300, and the vertical drive device 1211 is driven so that the front side inspection optical system 1211 is inspected. The height is adjusted according to the type of 1 and an inspection range (moving range of the spindle carriage 1004) is set to prevent the optical inspection unit 1210 and the tip 1002 of the hub 1001 from colliding with each other.

  On the other hand, the hub 1001 of the spindle carriage 1004 is also replaced according to the type of disk. Both the operation of exchanging the hub 1001 and the operation of inputting information relating to the type of the disk 1 to the overall control unit 1300 must be executed. However, there is a possibility that one of the tasks will be forgotten.

  At the time of inspection of the disk 1, the optical inspection unit 1210 performs an inspection close to the surface of the disk 1 in order to detect weak reflected / scattered light from minute defects on both sides of the disk 1. Therefore, when the diameter of the hub 1001 attached to the spindle carriage 1004 is larger than the diameter of the hub registered in the overall control unit 1300, the inspection range by the optical inspection unit 1210 and the tip portion 1002 of the hub 1001 are There is a risk that the optical inspection unit 1210 and the distal end portion 1002 of the hub 1001 collide with each other due to interference with the region.

  Therefore, in the present embodiment, a configuration in consideration of the case where any one of the operations is forgotten is adopted. That is, in this embodiment, when the spindle carriage 1004 is moving along the guide shaft 1006 toward the optical inspection unit 1200, the laser displacement meter 1050 is used for the upper surface of the disk 1 and the tip portion 1002 of the hub 1001. The size (diameter) is detected, and after confirming that it matches the information related to the type of the disc 1 registered in the overall control unit 1300, the disc 1 is transported to the optical inspection unit 1200. .

  Next, when the spindle carriage 1004 moves to the optical inspection unit 1200 along the guide shaft 1006, the laser displacement meter 1050 detects the height of the upper surface of the disk 1 and the tip portion 1002 of the hub 1001. The state will be described with reference to FIGS. 4A to 4C.

  First, as shown in FIG. 1A, the spindle carriage 1004 is moved along the guide shaft 1006 by the ball screw 1005 rotated by the stepping motor 1003 in a state where the disk is held by the hub 1001 in the delivery unit 1100. The position of FIG. 4A is reached. At this position, the laser displacement meter 1050 detects the height of the upper surface of the disk 1. When the spindle carriage 1004 further advances and reaches the position shown in FIG. 4B, the height of the tip end portion 1002 of the hub 1001 is detected by the laser displacement meter 1050. When the process further proceeds, as shown in FIG. 4C, the height of the upper surface of the disk 1 is detected again by the laser displacement meter 1050.

  The laser displacement meter 1050 measures the height of the upper surface of the disk 1 and the tip end portion 1002 of the hub 1001 at regular time intervals. In FIG. 5A, when the disk 1 is held by a hub 1001 having a relatively small diameter at the tip portion 1002 of the hub 1001, the laser displacement meter 1050 measures the height of the top surface of the disc 1 and the tip portion 1002 of the hub 1001. The results are shown. L in the figure indicates the case where the height of the surface detected by the laser displacement meter 1050 is low, and corresponds to the case where the height of the upper surface of the disk 1 is detected. On the other hand, H indicates the case where the height of the surface detected by the laser displacement meter 1050 is high, and corresponds to the case where the height of the tip portion 1002 of the hub 1001 is detected.

  FIG. 5A. When the range in which H is detected in the height detected by the laser displacement meter 1050 is narrow, FIG. 5B shows a case where the range where H is detected is relatively wide, and FIG. 5C shows a case where the range where H is detected is wider. ing.

  The overall controller 1300 receives an output signal from the laser displacement meter 1050 corresponding to L and H shown in FIGS. 5A to 5C, and when the spindle carriage 1004 reaches the position shown in FIG. The diameter of 1002 is obtained. Then, it is checked whether or not the obtained diameter corresponds to a preset type of the hub 1001, and if it corresponds to the preset type of the hub 1001, the stepping motor 1003 is controlled to control the spindle carriage 1004. Transport to the position of FIG.

  On the other hand, when the obtained diameter of the tip 1002 of the hub 1001 does not correspond to the preset type of the hub 1001 (the diameter of the tip 1002 depends on the type of the disk 1 registered in the overall control unit 1300 in advance. If it is larger or smaller than the predetermined dimension), the driving by the stepping motor 1003 is stopped, the spindle carriage 1004 is stopped at the position shown in FIG. 4C, and the diameter of the tip portion 1002 of the hub 1001 is abnormal. Outputs information indicating that there is.

  As described above, in this embodiment, the diameter of the tip portion 1002 of the hub 1001 is detected during the conveyance of the disk 1 from the delivery unit 1100 to the optical inspection unit 1200, so that the disk 1 being conveyed is entirely controlled in advance. After confirming that the disc 1 matches the type of the disc 1 set in the unit 1300, it is carried into the optical inspection unit 1200. This prevents a collision between the leading end portion 1002 of the hub 1001 and the optical inspection unit 1210 of the optical inspection unit 1200 due to a mismatch between the disk 1 being conveyed and the type of the disk 1 set in the overall control unit 1300. I can do it now.

  As mentioned above, although the invention made by the present inventor has been specifically described based on the embodiments, it is needless to say that the present invention is not limited to the above embodiments and can be variously modified without departing from the gist thereof. Yes.

  DESCRIPTION OF SYMBOLS 1 ... Disk 1000 ... Optical inspection apparatus of magnetic media 1001 ... Hub 1002 ... Hub tip part 1003 ... Stepping motor 1004 ... Spindle carriage 1005 ... Ball screw 1008 ... Encoder 1100 ... Delivery part 1050 ... Laser displacement meter 1200 ... Optical inspection Unit 1210: Optical inspection unit 1211 ... Front side inspection optical system 1212 ... Back side inspection optical system 1300 ... Overall control unit.

Claims (8)

A disk delivery unit that delivers a disk that is a magnetic medium to be inspected;
A disc inspection unit for optically inspecting the disc;
A disk transport unit that fits with a hole in the center portion of the disk and mounts the disk, and that mounts the disk on the hub and moves between the disk delivery section and the disk inspection section;
The size of the portion of the hub loaded with the disk mated with the hole of the central portion of the disk in the middle of moving from the disk delivery section to the disk inspection section with the disk transport unit mounted on the hub. Detecting means for detecting
Control means for stopping the movement of the disk transport unit when the size of the part of the hub that is detected by the detection means is fitted to the hole of the central part of the disk is different from a preset size. An optical inspection device for magnetic media.   2. The optical inspection apparatus for magnetic media according to claim 1, wherein the detecting means is a laser displacement meter, and the height of the upper surface of the disk mounted on the hub by the laser displacement meter and the central portion of the disk of the hub. Measure the height of the part mated with the hole of the disk, and detect the size of the part mated with the hole of the central part of the disk of the hub from the difference in the measured height in the control means An optical inspection device for magnetic media.   3. The optical inspection apparatus for magnetic media according to claim 1, wherein the disk inspection section optically inspects a front surface of the disk to detect a scratch or a defect on the front surface of the disk. A front side inspection optical system, and a back side inspection optical system that optically inspects the back side surface of the disk to detect scratches and defects on the back side surface of the disk. Optical inspection device.   3. The magnetic medium optical inspection apparatus according to claim 1, wherein the disk inspection unit further includes a driving unit that adjusts a height of the front inspection optical system according to a type of the disk to be inspected. An optical inspection apparatus for magnetic media, comprising: At the disk delivery section, the hole in the center of the disk, which is the magnetic medium to be inspected, is fitted to the tip of the hub and mounted on the hub,
The hub carrying the disc is transported to a disc inspection unit for optically inspecting the disc,
An optical inspection method for a magnetic medium for optically inspecting the disk in the disk inspection unit,
In the middle of transporting the hub loaded with the disk to the disk inspection section, the size of the portion of the hub loaded with the disk fitted with the hole in the central portion of the disk is detected, and A method for optically inspecting a magnetic medium, characterized in that the transport of the hub is stopped when a size of a portion fitted with a hole in a central portion is different from a preset size.   6. An optical inspection method for a magnetic medium according to claim 5, wherein a laser displacement meter is used to detect the size of a portion of the hub that is engaged with a hole in the central portion of the disk, and the laser Using a displacement meter, the height of the upper surface of the disk mounted on the hub and the height of the portion of the hub that fits into the hole in the center of the disk are measured, and the disk of the hub is determined from the difference in the measured height. An optical inspection method for magnetic media, comprising: detecting a size of a portion mated with a hole in a central portion of the magnetic medium.   7. The optical inspection method for a magnetic medium according to claim 5, wherein the disk inspection unit includes a front inspection optical system and a back inspection optical system, and the front side of the disk is used by using the front inspection optical system. The surface of the disc is optically inspected to detect scratches and defects on the front surface of the disc, and the back side surface of the disc is optically inspected using the back side inspection optical system. An optical inspection method for magnetic media, characterized by detecting scratches and defects in the magnetic media.   7. The optical inspection method for a magnetic medium according to claim 5, wherein the disk inspection unit adjusts the height of the front inspection optical system in accordance with the type of the disk to be inspected. Optical inspection method for magnetic media.

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