JP3349494B2 - Inspection method and inspection device for disk-shaped body - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention can inspect a surface of a disk-shaped object such as a disk-shaped recording medium (optical disk) for defects, and can shorten the inspection time while maintaining the inspection accuracy (resolution and detection ability). The present invention relates to an inspection method and an inspection device.

[0002]

2. Description of the Related Art As a device for inspecting defects on the surface of a disk-shaped recording medium such as an optical disk, a configuration shown in FIG. 5 is known. In the conventional inspection apparatus of FIG. 5, a light beam is emitted from the light source 10 to the disc-shaped recording medium 13, and the reflected light is received by a line camera 30 having pixels arranged in a line. A motor 31 controlled by a motor control device 32 for a disc-shaped recording medium 13
Scans one rotation while rotating the camera, and performs image processing on the video output signal of the line camera 30 by the image processing device 33. Based on the processing information, the CPU (central processing unit) 3
4 is analyzed for defects, and the result of the pass / fail judgment is
(Image display device) Displayed on 35 or output to sequencer 36. FIG. 6 shows an example of the relationship between the pixels (2048 pixels) of the line camera obtained by scanning one line in the radial direction and the amount of received light.

FIG. 7 is a schematic diagram showing an image memory taken by a line camera having pixels arranged in a line in the conventional inspection apparatus of FIG. The horizontal axis represents the number of pixels of the line camera arranged radially from the center of the disc-shaped recording medium toward the outer periphery. 1 is the innermost circumference, pixel No. 20
48 is the outermost periphery. The vertical axis represents the number of scans when the disk is rotated once, the first scan is at the start of disk rotation, and the 12,000 scan is at the end of disk rotation (after 360 ° rotation). As is clear from FIG. 7, the resolution in the radial direction of the disc-shaped recording medium is determined by the number of pixels arranged by the line camera, and the resolution in the circumferential direction of the disc-shaped recording medium is the number of scans during one rotation of the disc. Is determined. In addition, one scanning time is determined by a time for capturing information of one pixel of the line camera and an image processing device attached to the line camera. Therefore, the inspection time is determined by the number of scans during one rotation of the disk-shaped recording medium. It is determined.

[0004]

According to the above-described conventional inspection apparatus, it is necessary to keep the number of scans constant in order to maintain the resolution in the circumferential direction of the disk-shaped recording medium. The only way to shorten the inspection time while maintaining the resolution of the recording medium in the circumferential direction was to reduce the time to capture the information of one pixel. However,
If the time for taking in information of one pixel is shortened, the amount of received light per pixel is reduced, which causes a problem that the detection capability is reduced.

The present invention has been made in view of the above-mentioned problems of the prior art, and has an inspection method capable of shortening the inspection time for a disk-shaped body such as a disk-shaped recording medium while maintaining the inspection accuracy (resolution and detection ability). And an inspection device.

[0006]

In order to solve the above-mentioned problems, a method of inspecting a disk-shaped object according to the present invention irradiates a surface to be inspected of the disk-shaped object with a reflected light or a transmitted light. Light is received by the light receiving means in which a number of pixels are arranged in a line from the center of the disc toward the outer periphery, and information is taken in from the light receiving means while rotating the disc, and a normal part is determined based on the information. An inspection method for inspecting a defect of the disc-shaped body by discriminating a defective portion, wherein a large number of pixels of the light receiving unit are divided into a plurality of blocks, and the divided blocks are synchronized with each other. The method is characterized in that information obtained by this scanning is processed in parallel while scanning the inspection surface divided in accordance with the division in parallel.

According to this inspection method, while the blocks obtained by dividing a large number of pixels of the light receiving means are scanned in parallel while synchronizing each of the divided inspection surfaces, information obtained by this scanning is parallelized. And the inspection can be performed simultaneously without changing the number of scans, so that the inspection time can be shortened while maintaining the inspection accuracy such as resolution and detection capability.

In this case, it is preferable that information between the divided blocks is connected and processed.

A first defect signal is detected on one side at the boundary of the divided inspection surface, and a second defect signal is detected on the other boundary of the inspection surface on the other side. At this time, a connection process for connecting the first defect signal and the second defect signal can be performed. Thus, the defect signal detected near the boundary of the divided inspection surface can be accurately determined and determined. Note that the connection processing of the first defect signal and the second defect signal can be performed based on the number of scans.

Each information of the divided blocks is processed in parallel by an image processing device, integrated by a central processing unit, and processed as information of one disk-shaped body.
It can be determined and displayed on the display device. Also,
The surface to be inspected is preferably irradiated with visible light from a halogen lamp or the like or near infrared rays having a wavelength of about 800 to 1100 nm. Further, the information can be obtained from the difference in the amount of received light of the reflected light or the transmitted light, and the pass / fail of the determined defect can be determined based on the difference in the amount of received light.

According to the present invention, there is provided an apparatus for inspecting a disk-shaped object, comprising: a light source for irradiating a light beam to a surface to be inspected of the disk-shaped object; Light receiving means in which a large number of pixels are arranged in a line toward, a rotating means for rotating the disc-shaped body with respect to the light receiving means, and information obtained from the light receiving means while rotating the disc-shaped body. A discriminating unit for discriminating between a normal portion and a defective portion based on the information, and an inspecting device for inspecting the disc-shaped body for defects. Dividing, and scanning each of the surfaces to be inspected which are divided corresponding to the division while synchronizing each divided block, and processing information obtained by the scan in parallel. And

According to this inspection apparatus, the inspection method described above can be executed, and each of the divided inspection surfaces can be inspected simultaneously without changing the number of scans. Inspection time can be reduced while maintaining accuracy.

In this case, it is preferable that the discriminating means processes the information by linking information between the divided blocks.

Further, the discriminating means detects a first defect signal on one side at the boundary of the divided inspection surface, and detects a second defect signal on the other side at the boundary of the divided inspection surface. When a signal is detected, the first defect signal and the second
The defect signal can be determined by performing a linking process of linking the defect signal with the defect signal.

Further, the determining means includes an image processing device, a central processing device, and a display device. Each information of the divided blocks is processed in parallel by the image processing device, and then integrated by the central processing device. Then, the information is processed and determined as information of one disk-shaped body, and can be displayed on the display device.

It is preferable that the light source emits visible light or near-infrared light to the surface to be inspected. The determining means may determine a defect by obtaining the information from a difference in the amount of received light of the reflected light or the transmitted light, and determine whether the determined defect is acceptable based on the difference in the amount of received light. Can be.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a diagram showing a schematic configuration of a disk-shaped body inspection apparatus according to an embodiment of the present invention. FIG.
The inspection apparatus shown in FIG. 1 includes a line camera 14 as a light receiving means such as a one-dimensional CCD in which a large number of pixels are arranged in a line, and a video output signal from the line camera 14 is fetched to perform analog or digital filter processing. The image processing devices 19 and 20 for performing image processing such as waveform shaping by means of, for example, determine defects based on the image-processed signal subjected to waveform shaping, and compare with a predetermined threshold to perform binarization processing. A central processing unit (CPU) 21 for determining whether the defect is acceptable, a display device 22 for displaying the result of the determination on a display, a printer 23 for printing the result of the determination on recording paper, and a sequence of the inspection device based on the result of the determination. And a sequencer 24 to be controlled.

The inspection apparatus also includes a light source 10 such as a halogen lamp that irradiates a light beam on the back surface 13 b of the disk 13 that is the inspection target, a motor 11 that rotates the disk 13 for inspection, This motor 11 is connected to the CPU 21
And a motor control device 32 that performs control based on the instruction. The disk-shaped body 13 is a light-transmitting substrate, and after inspection, for example, a recording layer or the like is formed thereon to obtain a disk-shaped recording medium.

The line camera 14 is provided above the front surface 13 a so as to receive the transmitted light transmitted from the light source 10 to the back surface 13 b of the disk-shaped body 13, and a large number of pixels arranged in a line are formed in the disk. It is arranged so as to face from the center hole 13c of the body 13 to the outer periphery. A large number of pixels (for example, a total pixel number of 204
8) is divided in the line direction into two blocks on the inner peripheral side and the outer peripheral side. As shown in FIG. 1, the surface 13a of the disk 13 is inspected corresponding to the two divided blocks. The surface is elongated in the radial direction and is divided to form an inner peripheral imaging region 15 and an outer peripheral imaging region 16. The imaging area 15 has the pixel No. 1 to No. 1024, and the image pickup area 16 has the pixel No. No. 1025-No. 2
048.

The operation of the inspection device shown in FIG. 1 will be described. Motor control device 3 based on an instruction from CPU 21
Numeral 2 rotates the motor 11 to rotate the disc 13 at a constant rotation speed, while the light source 10 is turned on to irradiate the disc 13 from the back surface 13b. Next, line camera 1
Numeral 4 simultaneously scans the imaging areas 15 and 16 on the surface 13a of the disc 13 while synchronizing each other. Thereby, the transmitted light transmitted through the disc 13 in the imaging regions 15 and 16 is captured by each block of the line camera 14. The video output signal 17 (corresponding to the pixels No. 1 to No. 1024) of the inner peripheral imaging area 15 and the video output signal of the outer peripheral imaging area 16 are obtained from each block of the line camera 14 according to the amount of received light. Signal 18 (pixel No.
No. 1025-No. 2048) are output in parallel, input to the image processing devices 19 and 20, respectively, and image processing such as waveform shaping is performed in parallel and simultaneously. Processing signal is CP
The U (central processing unit) 21 performs processing by linking based on the number of scans, and performs integrated processing. Thereby, each piece of information obtained from each block (imaging areas 15 and 16) can be integrated as information of one disc-shaped body 13.

FIG. 2 shows the inspection apparatus shown in FIG.
Each pixel (pixels No. 1 to No. 10) in the inner peripheral block of the line camera 14 obtained by scanning the line
24A and 24B are diagrams illustrating examples of the relationship (a) between the amount of received light and the amount of received light and the relationship between each pixel (pixels No. 1024 to No. 2048) and the amount of received light in the outer peripheral block.

FIG. 3 shows the inspection apparatus of FIG.
4 inner peripheral side block (pixel No. 1 to No. 1024)
FIG. 9 is a diagram schematically showing an image memory (a) fetched by the step (b) and an image memory (b) fetched by the outer peripheral block (pixels No. 1024 to No. 2048).
o. And the vertical axis represents the number of scans. The image memory of FIG. 3A processes the video output signal 17 by the image processing device 19, and the image memory of FIG.
Is processed by the image processing apparatus 20.

For example, the disc-shaped body 13 has a defect such as a pinhole, the amount of light received by the line camera 14 changes, and a difference occurs in the amount of light received between pixels before and after the line camera (with no defect). As a result of waveform shaping at 19 and 20, FIG.
When a + peak aa like this appears, this peak aa
Is compared with a preset threshold value a1, and if it is not less than a1, the CPU 21 determines that the signal is a defect signal. The defect position can be specified on the image memory as a defect signal 39 as shown in FIG. Similarly, when a negative peak bb as shown in FIG. 2B appears, the value of this peak bb is set to the threshold value b1.
If it is less than or equal to b1, the CPU 21 determines that the signal is a defect signal. The defect position can be specified on the image memory as a defect signal 40 as shown in FIG. In this manner, the inspected surface of the front surface 13a can be inspected to determine a normal portion and a defective portion. Then, when the defect signal determined as a defect exceeds a predetermined threshold, the defect can be determined to be defective (fail). The predetermined thresholds may be the thresholds a1 and b1 in FIGS. 2A and 2B, but may be set separately. In addition, as shown in FIG. And the number of scans, the position of the detected defect can be specified on the actual inspected surface.

Next, the information on the defect signals 39 and 40 as described above can be displayed on the display device 22 and printed by the printer 23, and output to the sequencer 24 a judgment on the quality of the inspected disk-shaped body. be able to. If the result of the determination is defective (failed), the failed disk-shaped body can be removed from the inspection process.

In the above-described inspection process, if the time for taking in information of one pixel of the line camera 14 as the light receiving means is the same as the conventional one, the time for one scan is as shown in FIG.
(A) and (b), each block scans simultaneously in parallel, and output signals 17 and 18 thereof are output to the image processing apparatus 1.
Since the processing is performed simultaneously in steps 9 and 20, it takes only half the time as compared with the related art. Here, when the cycle of taking in information of one pixel is 20 MHz, and the entire circumference of the disc is scanned 12,000 times by the line camera of 2048 pixels, it takes 1.23 seconds with the conventional inspection apparatus (FIG. 5). But,
According to the inspection apparatus of the present embodiment, only 0.61 seconds is required, and the inspection time can be reduced to half. In addition, since each imaging region can be inspected simultaneously without changing the number of scans, the inspection time can be reduced while maintaining inspection accuracy such as resolution and detection capability. Thereby, the production efficiency of the entire product can be improved while maintaining the quality of the product.

As described above, in order to divide the surface to be inspected, scan each of the divided imaging regions simultaneously, and simultaneously process the obtained signals in parallel by different image processing apparatuses, the inspection time is required. Can be shortened. In the present embodiment, the inspection time can be reduced to half by dividing the total number of pixels of the line camera into two. However, the present invention is not limited to this, and the inspection time may be reduced to three or more. The inspection can be further speeded up. Further, the inspection device of the present embodiment detects surface defects such as pinholes, scratches, wetness, and foreign substances, but can also detect internal defects.

Next, referring to FIG. 4, a description will be given of a determination method when a defect signal is found near the boundary where the number of pixels of the light receiving unit is divided in the inspection apparatus of FIG. For example, as shown in FIG. 4A, in the image memory of the inner peripheral block, the defect signal 41a is set to the pixel No. 1024 appear on the fourth scan and the fifth scan. On the other hand, as shown in FIG.
1b is the pixel No. 4th scan of 1025, 1026,
If it appears on the fifth scan, the CPU 21 outputs a defect signal 4
A process for linking 1a and 41b based on the number of scans is performed. Since the defect signals 41a and 41b are detected with the same number of scans, the CPU 21 determines that the defect signals are continuous. In this way, when the defect signal detected at the boundary between the two blocks is determined to be one,
The pass / fail judgment of the defect is performed based on the set size of the defect.
Further, for example, when the defect signal 41c is the pixel No. When it appears in the third scan of 1025, the defect signals 41a, 41
b and 41c are determined as one continuous defect signal.

In FIG. 4A, the defect signal 42 is
o. Appears on 1024 8th and 9th scans,
On the other hand, in FIG. 102
In the case where it appears on the eleventh scan of 5,1026, the number of scans is not the same, so that the defect signals 42 and 43 are determined as independent defect signals.

When a defective signal is found at the boundary of each of the divided blocks as described above, a linking process is performed based on the number of scans, and it can be determined whether or not the signals are the same continuous defective signal.

As described above, the present invention has been described by the embodiments. However, the present invention is not limited to these embodiments.
Various modifications are possible within the scope of the technical idea of the present invention. For example, a light beam from the light source may be applied to the disc-shaped body, and the reflected light may be received by the line camera of the light receiving unit, and the same effect as in the case of the transmitted light can be obtained. Also,
The light source may be capable of emitting near-infrared light having a wavelength of about 800 to 1100 nm.

The disk-shaped object to be inspected may be an optical disk or a magneto-optical disk, and specifically includes a CD, CD-R, CD-RW, MD, DVD, etc. A light-transmitting substrate for a medium may be used, but the present invention is not limited thereto, and it is a matter of course that a disk-shaped body for other uses may be used.

[0032]

According to the inspection method and the inspection apparatus of the present invention, without lowering the inspection accuracy (resolution, detection ability),
The inspection time can be shortened, and the quality of the disk-shaped body can be maintained and the productivity can be improved.

[Brief description of the drawings]

FIG. 1 is a diagram showing a schematic configuration of a disk-shaped body inspection apparatus according to an embodiment of the present invention.

FIG. 2 shows the relationship (a) between each pixel in the inner peripheral block and the amount of received light of the line camera 14 obtained by scanning one line in the radial direction with the inspection apparatus of FIG. It is a figure showing the example of the relation (b) with the amount of light reception.

FIG. 3 schematically shows an image memory (a) captured by an inner peripheral block and an image memory (b) captured by an outer peripheral block in a line camera as a light receiving means in which pixels are arranged in a line in the inspection apparatus of FIG. FIG.

4 is a view similar to FIG. 3 for explaining defect determination when a defect appears at a boundary between an inner peripheral block and an outer peripheral block in the line camera in the inspection apparatus of FIG. 1;

FIG. 5 is a view showing a schematic configuration of a conventional disk-shaped recording medium inspection apparatus.

FIG. 6 is a diagram showing a relationship between each pixel of a line camera and a received light amount obtained by scanning one line in a radial direction with a conventional inspection device.

FIG. 7 is a diagram schematically illustrating an image memory captured by a line camera having pixels arranged in a line in a conventional inspection apparatus.

[Explanation of symbols]

Reference Signs List 10 light source 11 motor 32 motor control device 13 disc-shaped body 13a surface of disc-shaped body (surface to be inspected) 13b back surface of disc-shaped body 14 line camera (light receiving means) 15 inner peripheral side imaging region (divided surface to be inspected) 16) Imaging area on outer peripheral side (divided surface to be inspected) 19, 20 Image processing device (determination means) 21 Central processing device (CPU)
(Determination means) 22 display device 23 printer 24 sequencer 39, 40 defect signal 41a, 41b, 41c defect signal

──────────────────────────────────────────────────続 き Continuation of the front page (51) Int.Cl. ⁷ identification code FI G11B 20/18 G11B 20/18 572F (58) Investigated field (Int.Cl. ⁷ , DB name) G01B 11/30 G01N 21 / 95 G11B 7/26 G11B 20/18 501 G11B 20/18 572

Claims (12)

(57) [Claims] 1. A light-receiving means which irradiates a light beam to a surface to be inspected of a disk-shaped body and reflects or transmits the reflected light or transmitted light from the center of the disk-shaped body toward an outer periphery thereof in a line form. Receiving an information from the light receiving means while rotating the disk-shaped body, and inspecting the disk-shaped body for defects by determining a normal part and a defective part based on the information, Dividing a large number of pixels of the light receiving means into a plurality of blocks,
The divided blocks are scanned in parallel on the surface to be inspected, which is divided in the radial direction corresponding to the division while synchronizing with each other, and information obtained by this scan is processed in parallel. Inspection method for disk-shaped objects. 2. The inspection method according to claim 1, wherein information between the divided blocks is connected and processed. 3. A first defect signal is detected on one side at a boundary between the divided inspection surfaces, and a second defect signal is detected on a boundary between the divided inspection surfaces on the other side. 3. A connection process for connecting the first defect signal and the second defect signal.
Inspection method described in 1. 4. The information of each of the divided blocks is processed in parallel by an image processing device, integrated by a central processing unit, processed as information of one disk-shaped body, determined, and displayed on a display device. 2. The display according to claim 1,
The inspection method according to 2 or 3. 5. The method according to claim 1, wherein the surface to be inspected is irradiated with visible light or near infrared light.
Inspection method described in 1. 6. A method for determining a defect by obtaining the information from a difference in the amount of received light of the reflected light or the transmitted light, and determining whether or not the determined defect is acceptable based on the difference in the amount of received light. The inspection method according to any one of claims 1 to 5, wherein 7. A light source for irradiating a light beam to a surface to be inspected of a disc-shaped body, and a large number of pixels arranged linearly from the center of the disc-shaped body toward the outer periphery to receive reflected light or transmitted light of the light beam. Light receiving means in which are arranged, rotating means for rotating the disc-shaped body with respect to the light receiving means, information obtained from the light receiving means while rotating the disc-shaped body, and a normal part based on the information. And a discriminating means for discriminating between a defective portion and a discriminating portion, and an inspecting device for inspecting a defect of the disk-shaped body, wherein a large number of pixels of the light receiving unit are divided into a plurality of blocks,
The divided blocks are scanned in parallel on the surface to be inspected, which is divided in the radial direction corresponding to the division while synchronizing with each other, and information obtained by this scan is processed in parallel. Inspection device for disk-shaped objects. 8. The inspection apparatus according to claim 7, wherein the discriminating unit connects and processes information between the divided blocks. 9. The determination means detects a first defect signal on one side at a boundary of the divided inspection surface and a second defect at a boundary of the divided inspection surface on the other side. The inspection apparatus according to claim 7, wherein when a signal is detected, a connection process for connecting the first defect signal and the second defect signal is performed to determine a defect. 10. The discrimination means includes an image processing device, a central processing unit, and a display device. Each piece of information of the divided blocks is processed in parallel by the image processing device, and then integrated by the central processing device. The inspection apparatus according to claim 7, 8 or 9, wherein the information is processed as one piece of disc-shaped body information, determined, and displayed on the display device. 11. The apparatus according to claim 7, wherein the light source irradiates the inspection surface with visible light or near-infrared light.
The inspection device according to 8, 9, or 10. 12. The discriminating means discriminates a defect by obtaining the information from a difference in the amount of received light of the reflected light or the transmitted light, and determines whether or not the determined defect is acceptable based on the difference in the amount of received light. The method according to claim 7, wherein the determination is performed.
The inspection device according to any one of claims 1 to 7.