JPH11304722A - Method and device for inspecting disk - Google Patents

Abstract

PROBLEM TO BE SOLVED: To more quickly inspect a plurality of kinds of disks as compared with the past while satisfying inspection accuracy. SOLUTION: Illumination light 3 is applied to a surface 1a to be inspected of a disk 1 with a light reflection property from one side of a normal line 2, at the same time, reflected light 4 from the surface 1a to be inspected is received at the opposite side of the normal line 2 for obtaining a gray image 5 of the surface 1a to be inspected, transmission light 6 from the disk 1 is received at the side of a surface opposite to the surface 1a to be inspected of the disk 1, a hole and the defect of a light transmission part are detected by the transmission light, the gray-level image 5 is subjected to image processing for detecting a noise image 7 of the defect by image recognition, and the defect of the surface 1a to be inspected is detected.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to CD, PD, DV
TECHNICAL FIELD The present invention relates to a light-reflective disk as a disk-type data storage medium such as D, and to a disk inspection method and apparatus for detecting surface defects.

[0002]

2. Description of the Related Art Conventionally, these discs are inspected using a method and apparatus disclosed in Japanese Patent Application Laid-Open No. 03-172527. This method uses an optical disk playback device having an optical pick, performs a playback operation on each disk to be inspected one by one, and determines whether playback can be performed without malfunction.
The quality of the disc is detected with high accuracy.

[0003]

Incidentally, there are discs of various reproduction systems. Therefore, in the above-described method using the reproducing apparatus, the same number of types of reproducing apparatuses are required in accordance with the type of the disc. Therefore, enormous capital investment was required to inspect various disks.
In addition, if the reproducing operation is performed for each disk for inspection, it takes several tens of minutes to inspect each disk, so that the inspection efficiency is low and the cost is high. In order to cope with an increase in the number of productions due to the approximate increase in demand for disk-type data storage media, simultaneous inspection using a plurality of playback devices further increases equipment costs, which further increases costs.

The present inventors have been conducting various studies in an attempt to solve these problems. Considering that image data of the surface to be inspected is subjected to image processing to detect defects by image recognition, a grayscale image obtained by light reception is binarized and detected as in normal image processing. As a result, a binarized image C as shown in FIG. 6 is obtained, and a normal pattern a and a noise image b provided for reading and writing on the disk are detected. The noise image b that can be detected by the pattern matching method of the pattern a or the like and that does not match the noise can be easily detected as a defect. However, one of the regular patterns a
Finally, there is a noise image b, which is not detected but is erroneously detected. In addition, since the disk is often a combination of a plurality of layers, there is an erroneous detection in the above-described image processing and image recognition due to missing a small hole or a defect in the light transmitting portion. In addition, the types of defects include holes, light-transmitting portions, foreign matter, scratches, stains, and the like that become noise in reproduction, and these need to be distinguished and detected with high accuracy in distinction from various regular pattern images. However, this has not yet been fully responded.

An object of the present invention is to provide a disk inspection method and apparatus capable of inspecting a plurality of types of disks at a higher speed than before, while satisfying the inspection accuracy.

[0006]

In order to achieve the above object, a disk inspection method according to the present invention irradiates an inspection surface of a light reflective disk with illumination light from one side of a normal line. At the same time, the reflected light from the surface to be inspected is received on the side opposite to the normal line to obtain a grayscale image of the surface to be inspected, and the light is reflected from the disk on the side opposite to the surface to be inspected of the disk. One method is to receive transmitted light, detect defects in holes and light-transmitting parts using transmitted light, perform image processing on grayscale images, detect noise images of defects by image recognition, and detect defects on the inspection surface. Features.

As described above, the light-reflective surface to be inspected is irradiated with illumination light from one side of the normal line, and the reflected light is received on the opposite side of the normal line, thereby providing light reflectivity. A shaded image corresponding to the difference in the reflection conditions of the inspected surface is obtained. The grayscale image data includes various normal pattern images and various noise images. By performing image processing on these images, it is possible to detect only a defect due to a difference in density or a difference in pattern. On the other hand, even if there is a hole or a hole of a defect that is missed by this image recognition, it can be easily and reliably received by receiving the transmitted light of the illumination light to the inspection surface side of the disk. Can be detected.
Such a defect detection method can be similarly applied to discs of various playback systems, and furthermore, by detecting transmitted light and performing image processing and image recognition of a grayscale image by reflected light, only a defect can be detected at high speed and with high accuracy. Can be detected. Therefore, both equipment costs and inspection costs are reduced.

When there is a regular pattern on the surface to be inspected, the regular pattern is not recognized as a defect by recognizing the regular pattern in a grayscale image and distinguishing it from a defect. In particular, when a pattern neighborhood including a neighborhood of a regular pattern that is image-processed and image-recognized is set, there is no regular pattern outside the neighborhood of the pattern. By performing a binarization process in accordance with the defect, noise images of all the various types of defects having different reflection characteristics appear, and it is possible to detect the noise image without omission with high accuracy. Also, in the pattern vicinity area, by distinguishing a regular pattern whose image has been recognized from a defect, a defect can be detected with high accuracy by image recognition as in the case of the outside.

The inspection method as described above includes an illuminator for illuminating a surface to be inspected of a light reflective disk from one side of a normal line,
A first light receiving device for receiving light reflected from the surface to be inspected on a side opposite to the normal line of the surface to be inspected, and receiving a transmitted light from the disk on a surface of the disk opposite to the surface to be inspected; Image processing for detecting a disk defect based on recognition data obtained by performing image processing on gray-scale image data from the first light receiver, image recognition of the gray image data from the first light receiver, and transmitted light data received by the second light receiver According to the disk inspection apparatus characterized in that the apparatus is provided, the operation is automatically and efficiently and stably achieved in accordance with a predetermined program by the operation of each apparatus. In addition, if the image of the entire surface to be inspected is made so that the partial detection unit extends over the entire surface to be inspected while rotating the disk, the entire surface to be inspected can be inspected efficiently with a small-scale inspection device. It is preferable because it can be performed. In addition, if the illuminator is equipped with a light amount adjustment unit that adjusts the amount of illumination light, it is possible to freely set the degree of illumination that can obtain a grayscale image in which defects can be most easily detected, in response to disks and defects with different reflection characteristics, The accuracy and efficiency of defect inspection are improved.

[0010] Further objects and features of the present invention will become apparent from the following detailed description and drawings. The above features of the present invention can be used alone or in combination in various combinations.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to FIGS. 1 to 6 together with embodiments thereof, to provide an understanding of the present invention.

The disk inspection method according to the present embodiment is an example of a case in which various defects are detected by using a disk 1 as shown in FIG. However, the present invention is not limited to this, and it is possible to detect various kinds of defects having different reflection characteristics of the disks, including holes and light-transmitting portions, and to detect only one type of defect. It is.

Referring to the disk inspection apparatus according to the embodiment of the present invention shown in FIG. 1, the illumination light 3 is applied to the inspection surface 1a of the disk 1 from one side of the normal 2 at the same time. On the side opposite to the normal, the reflected light 4 from the surface 1a to be inspected is received to obtain a gray image 5 of the surface 1a to be inspected as shown in FIG.
Receives the transmitted light 6 from the disk 1 on the side opposite to
A defect in a hole or a light transmitting portion is detected by the transmitted light 6, an image processing is performed on the grayscale image 5, a noise image 7 of the defect is detected by image recognition, and a defect on the inspection surface 1a is detected.

As described above, by irradiating the light-reflective inspected surface 1a with the illumination light 3 from one side of the normal 2 and receiving the reflected light 4 on the side opposite to the normal 2, A gray image 5 corresponding to the difference in the reflection conditions of the inspection surface 1a having light reflectivity is obtained. For this purpose, it is preferable that the incident angle of the illumination light 3 is about 10 ° to 80 ° with respect to the inspection surface 1a. If the angle is 10 ° or less, it is difficult to obtain a grayscale image corresponding to the difference in the reflectance of the inspection surface 1a due to the reflected light 4. If it exceeds 80 °, light or interference of equipment occurs, which is not suitable for inspection.

The reflected light 4 is a mirror-target position at the boundary between the illumination light 3 and the normal 2. In addition, according to the type of the disk, for example, the material and thickness of the disk 1 or each layer constituting the disk, or the type of defect, a gray image 5 suitable for inspection corresponding to the difference in their reflection characteristics is obtained. It is preferable to adjust the amount of illumination light 3. By this adjustment or depending on the state of light reception, it is possible to deviate from the above angle range.

The light and shade image 5 shown in FIG. 3 includes various regular images such as a regular pattern 8 as shown in FIG. 3 provided for reading and writing and various noise images 7. 5, only a defect can be detected with high accuracy, as in the noise image 7 of the binarized detection image 5a shown in FIG. On the other hand, even if there is a hole or a hole of a defect that is missed by this image recognition, the transmitted light 6 of the illumination light 3 to the side opposite to the inspection surface 1a of the disk 1 is received. By doing so, this can be easily and reliably detected. Such a defect detection method can be similarly applied to discs of various reproduction systems, and furthermore, receiving the transmitted light 6 and
By image processing and image recognition of the grayscale image 5 by the reflected light 4, only the defect can be detected with high accuracy at a high speed of about several seconds. Therefore, both equipment costs and inspection costs are reduced.

When the regular pattern 8 as described above is present on the surface 1a to be inspected, the regular pattern is subjected to image processing such as binarization in the grayscale image 5 and image recognition is performed to distinguish the regular pattern from a defect. 8 is not detected as a defect. However, even in this case, if the defect noise image 7 overlaps the regular pattern 8, it is difficult to detect this. Thus, when a pattern neighborhood 11 such as the grayscale image 5 shown in FIG. 4 including the neighborhood of the regular pattern 8 subjected to image processing and image recognition is set, there is no regular pattern 8 outside the neighborhood 11 of the pattern. In the same image processing state or by performing binarization processing according to the defect having the lowest density, it is possible to obtain a noise image 7 for all the various types of defects having different reflection characteristics and to detect it with high accuracy without omission. it can. In addition, by discriminating the regular pattern 8 whose image has been recognized from the defect in the pattern neighborhood 11,
As with the outside, highly accurate defect detection can be performed by image recognition.
In order to distinguish the regular pattern 8 from the defect, the corresponding pattern may be detected by pattern matching or the like, and the other pattern may be image-recognized as a noise image corresponding to the defect.

In order to achieve the above-described inspection method, the inspection apparatus of the present embodiment supports the disk 1 on a rotating disk 13 connected to a motor 12 as shown in FIG. The gray image of the inspection surface 1a is taken in while rotating. According to one embodiment, the diameter of the disk 1 is 120 mm, the diameter of the central hole 1b is 15 mm, and the diameter of the turntable 13 is about 21 mm. The surface 1a to be inspected of the disk 1 is a range in which the disk 1 can be read and written, and has a diameter of 46 mm to 120 mm. Therefore, the hole 1b, which is one of the regular patterns at the center of the disk 1, is outside the range of the surface 1a to be inspected, and does not enter the grayscale image 5. However, since the hole 1b is a normal image even if it enters the grayscale image 5, it can be distinguished from a defect by the image processing and image recognition.

In order to capture the grayscale image 5 of the entire inspection surface 1a of the rotating disk 1, an illuminator 14 irradiating the illumination light 3 illuminates the radial line of the inspection surface 1a of the disk 1 with the band illumination light 3. Then, if the strip-like reflected light 4 is received by the light receiver 15, a gray image 5 of the inspection surface 1a can be obtained by one rotation of the disk 1. However, even if the gray scale image 5 is taken in by sequentially scanning from one of the inner and outer diameter sides to the other by the point illumination, it can be achieved at a higher speed than when the disk 1 is reproduced. The illuminator 14 has a light amount adjusting section 14a for adjusting the light amount, and can be adjusted manually. There is also provided a light receiver 17 for receiving the transmitted light 6 to the side opposite to the disk 1 in the range of the inspection surface 1a of the disk 1. The optical axis of each of the illuminator 14 and the light receiver 15 is mirror-symmetric with respect to the normal 2, and the illuminator 1
The optical axis of the light receiver 4 and the light receiver 17 need to satisfy a predetermined positional relationship with each other so that their optical axes are on the same line. It is supported so that the side angle can be adjusted. It is preferable that the angles can be adjusted in conjunction with each other while maintaining a predetermined angle and positional relationship.

The received light data from the light receivers 15 and 17 are input to an image processing section 20 where the determination of the presence or absence of the detection of the transmitted light 6 and the image processing and image recognition of the gray image using the reflected light 4 are performed. Done. Specifically, the image processing unit 2
0, as shown in FIG. 2, first determines the presence or absence of the transmitted light 6. As a result, if the transmitted light 6 is present, the disc 1 can be immediately determined to be defective, and complicated image processing and image recognition operations can be omitted. If there is no transmitted light 6, the process proceeds to the detection of a defect by image processing and image recognition, and the light receiving data of the reflected light 4 from the inspected surface 1a is stored in the image storage unit 22. As a result, when a predetermined density image 5 for one disk 1 is accumulated, the regular pattern 8 is extracted by the pattern extraction unit 23. When the regular pattern 8 is extracted, the pattern neighborhood 11 including the neighborhood of the regular pattern 8 extracted by the pattern neighborhood definition unit 24 is defined. Next, in the near-pattern area defect extracting section 25 and the near-pattern outside defect extracting section 26, the above-described defect extraction operation corresponding to each is performed.

If any one has a defect, it is determined to be a defective disk, and if there is no defect, it is determined to be a good disk. If there is no regular pattern 8 in the pattern extracting unit 23,
If there is a noise image 7, the pattern non-defect detection unit 27 detects it as a defect and determines it as a defective disk. If there is no noise image 7, it determines that there is no defect and it is a good disk.

As a result, the above-described characteristic defect detection for one disk 1 is automatically and efficiently achieved stably according to a predetermined program.

[0023]

According to the disk inspection method of the present invention,
For discs of various playback systems, by receiving transmitted light and performing image processing and image recognition of grayscale images by reflected light,
Only defects can be detected at high speed and with high accuracy. Therefore, both equipment costs and inspection costs are reduced.

Further, even if there is a regular pattern on the surface to be inspected, this is not detected as a defect, and the regular pattern is not affected by the regular pattern outside the area near the pattern set for the recognized regular image. The defect of the defect can be detected with high accuracy by image recognition without the influence of the regular pattern inside.

According to the disk inspecting apparatus of the present invention, it is achieved efficiently and stably automatically according to a predetermined program.

[Brief description of the drawings]

FIG. 1 is a schematic side view showing a disk inspection method and apparatus according to an embodiment of the present invention.

FIG. 2 is a flowchart illustrating an internal function and an example of a processing operation of an image processing unit of the apparatus in FIG. 1;

FIG. 3 is an example of a grayscale image captured from a surface to be inspected of a disk in the method and apparatus of FIG. 1;

FIG. 4 is a setting example of a pattern vicinity area for a normal pattern in the grayscale image of FIG. 3;

FIG. 5 is an example of a binarized detection image detected by setting a pattern vicinity area in FIG. 4;

FIG. 6 is an example of a defect detection image obtained by binarization performed by the present inventors.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Disc 1a Inspection surface 2 Normal line 3 Illumination light 4 Reflected light 5 Grayscale image 6 Transmitted light 7 Noise image 8 Regular pattern 11 Pattern neighborhood 13 Turntable 14 Illuminator 14a Light amount adjusting unit 15, 17 Light receiver 20 Image processing Unit 22 Image storage unit 23 Pattern extraction unit 24 Pattern near area definition unit 25 Pattern near area defect extraction unit 26 Pattern near area outside defect extraction unit

Claims (6)

[Claims] An illumination light is radiated to a surface to be inspected of a light-reflective disk from one side of a normal line, and reflected light from the surface to be inspected is received at a side opposite to the normal line. In addition to obtaining a grayscale image of the surface to be inspected, the transmitted light from the disk is received on the side of the disk opposite to the surface to be inspected, and the transmitted light detects defects in holes and light-transmitting parts, and the grayscale image is imaged. A disk inspection method, comprising: detecting a noise image of a defect by image recognition to detect a defect on a surface to be inspected; 2. When there is a regular pattern on the surface to be inspected,
The disk inspection method according to claim 1, wherein the gray image is subjected to image processing to recognize a regular pattern, thereby discriminating the image from a defect. 3. A method of irradiating illumination light on a surface to be inspected of a light-reflective disk from one side of a normal line, and receiving reflected light from the surface to be inspected on a side opposite to the normal line. A shaded image of the surface to be inspected is obtained, and the shaded image is subjected to image processing to set a pattern neighborhood including a neighborhood of a recognized regular image. Except for a disc inspection method in which an operation for detecting a noise image of a defect by image recognition is performed without such an operation outside. 4. The disk inspection method according to claim 3, wherein the transmitted light from the disk is received on the side of the disk opposite to the surface to be inspected, and holes or light transmitting portions are detected by the transmitted light. 5. An illuminator for illuminating a surface to be inspected of a light-reflective disk from one side of a normal line, and receiving reflected light from the surface to be inspected on a side opposite to the normal line to the surface to be inspected. A first light receiving device, a second light receiving device for receiving the transmitted light from the disk on the side opposite to the surface to be inspected of the disk, and an image obtained by performing image processing on the gray image data from the first light receiving device An apparatus for inspecting a disk, comprising: an image processor for detecting a defect of the disk based on the recognized data and the transmitted light data received by the second light receiver. 6. The disk inspection apparatus according to claim 5, wherein the illuminator includes a light amount adjusting unit for adjusting an illumination light amount.