JPH0861919A - Center position detecting method for optical disc - Google Patents

Abstract

PURPOSE: To detect the center position of an optical disc by the recognition of an image. CONSTITUTION: An optical disc is photographed and, among the read images thereof, a reflected light image 120 from a ring type mirror surface section formed by a reflective film is separated. Then, the vicinity of the center of the image 120 is retrieved and scanned in a plurality of rows along X-axis direction. Furthermore, the positions of partial images forming a pair are recognized for every row, and midpoints Xc1, Xc2 and Xc3 between both partial images are calculated. Then, the mean value thereof is adopted as the center coordinates of the ring type reflected light image in the X-axis direction. In addition, the vicinity of the center of the image 120 is retrieved and scanned in a plurality of rows along Y-axis direction, and the positions of partial images forming a pair are recognized for every row. Then, midpoints Yc1, Yc2 and Yc3 between both partial images are calculated and the mean value thereof is adopted as the center coordinates of the ring type reflected light image in the Y-axis direction. Thereafter, the center coordinates in the X- and Y-axis directions are detected as the center position of the optical disc.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disc inspection method, and more particularly to a disc center detection method for recognizing an identification mark attached to a ring-shaped mirror surface by a reflection film.

[0002]

2. Description of the Related Art An optical disc is produced by a process in which aluminum is vapor-deposited as a reflective film on a molded signal forming surface and a protective coating material is applied on the upper surface of the optical disk in order to prevent oxidation of the reflective film. It is common. An identification mark for identifying what is recorded on each optical disc is a ring-shaped mirror surface portion 1 formed by a reflection film in a portion adjacent to the signal forming surface 11 as shown in FIG.
2 are arranged in an arc shape and given. When the identification symbol string 10 is image-recognized and the quality of each symbol is determined and the type of the optical disc 1 is identified, first, the arc center of the identification symbol string arranged in an arc shape, that is, the center position of the optical disc is correctly detected. Must. Conventionally, such center detection position detection adopts a method of recognizing a center mark 22 attached to a taper pin 21 fixed to the center of a table 2 for positioning and mounting an optical disk, as shown in FIG. 5, for example. Was there.

[0003]

In the method for recognizing the center mark by recognizing the center mark on the upper surface of the taper pin as described above, there is a sticking error at the time of adding the center mark, a reflection film at the time of fitting the optical disk and the taper pin, and a reflection film. It is necessary to consider the vapor deposition position error and so on. For this reason, in order to keep the positioning and placing accuracy of the disk within a certain error, a mechanism of appropriate accuracy is required. The present invention provides a method for detecting the center position of an individual optical disk with a mechanism that allows the ring-shaped mirror surface portion of the optical disk to enter the imaging field of view without requiring such accuracy. Therefore, the purpose is to accurately recognize the identification symbol.

[0004]

According to the center position detecting method of the present invention, an image of an optical disk is picked up, a reflected light image from a ring-shaped mirror surface portion by a reflecting film is cut out from the captured image, and the reflected light image is obtained. Multiple lines are scanned in the X direction near the center of. For each line, the positions of the partial images forming a pair are recognized, the midpoint between the partial images is calculated, and the average value thereof is taken as the X-direction center coordinate of the ring-shaped reflected light image. Then, near the center of the reflected light image, a plurality of lines are searched and scanned in the Y direction,
For each line, the position of the pair of partial images is recognized, the midpoint between the partial images is calculated, and the average value thereof is taken as the Y-direction center coordinate of the ring-shaped reflected light image. The center coordinate of is detected as the center position of the optical disc.

[0005]

By the image recognition, the ring-shaped mirror surface image of the optical disk is cut out, and the center coordinates in the X and Y directions are obtained. This center coordinate is assumed to be the center coordinate of the optical disc, and thereafter, image recognition of the identification mark is advanced.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A center position detecting method of the present invention will be described with reference to the drawings. FIG. 1 is a plan view of the optical disc 1, and FIG. 4 is a schematic configuration diagram for carrying out the center position detecting method of the present invention. The same components as those in the conventional example are designated by the same reference numerals. 2 is a table on which the optical disc 1 is placed, 3 is an image pickup means for picking up an image of the optical disc placed on the table 2 from above, and 4 is an image recognized by the image pickup means 3,
It is a center detection device that detects the center position of the optical disk 1. As shown in FIG. 1, the image pickup means 3 is arranged at a distance such that the ring-shaped mirror surface portion 12 of the optical disk is sufficiently included in the visual field 13. Further, a ring-shaped surface light source may be arranged between the image pickup means 3 and the table 2 in order to improve the quality of the captured image. The center detecting device 4 also has a function of detecting the center position of the optical disc 1 and then character-recognizing the identification symbol attached to the ring-shaped mirror surface portion to determine whether the character is good or bad and to identify the type of the optical disc. .

The operation of this embodiment will be described. The optical disk 1 is placed on the table 2 by a transfer means (not shown), and the imaging means 3 images the surface of the optical disk existing in the visual field 13. The captured image is input to the center detection device 4, and the image recognition work is started. First, the center detection device 4 cuts the reflected light image of the ring-shaped mirror surface portion 12 from other images. Therefore, a density histogram of the input image is created, and a threshold value of a level at which the reflected light image can be separated is determined. Then, binarize the image with this threshold,
The ring-shaped reflected light image 120 shown in FIG. 2 is recognized.

FIG. 3 shows a recognized ring-shaped reflected light image 12
It is explanatory drawing of the method of calculating | requiring a ring center based on 0. The center detection apparatus 4 scans the vicinity of the center of the reflected light image 120 at three places parallel to the X direction, and searches the position of an image. Peripheral position coordinates (X11 and X
12, X21 and X22, X31 and X32) midpoint Xc1, Xc2, X
Calculate c3 by the following formula.

Xc1 = (X11 + X12) / 2

Xc2 = (X21 + X22) / 2

Xc3 = (X31 + X32) / 2

The average value of the calculated coordinates of each midpoint is taken as the center coordinate of the ring-shaped mirror surface portion in the X direction.

Similarly, the center detecting device 4 uses the reflected light image 12
The position of the image is searched by scanning three points near the center of 0 in parallel with the Y direction. For each scanning line, the midpoints Yc1, Yc2, Yc3 between the outer peripheral position coordinates (Y11 and Y12, Y21 and Y22, Y31 and Y32) of the paired partial images are calculated by the following formula.

Yc1 = (Y11 + Y12) / 2

Yc2 = (Y21 + Y22) / 2

Yc3 = (Y31 + Y32) / 2

The average value of the obtained coordinates of each midpoint is taken as the Y-direction center coordinate of the ring-shaped mirror surface portion. The X-direction and Y-direction center coordinates of the ring-shaped mirror surface portion thus calculated are recognized as the center coordinates of the optical disc 1, and the process proceeds to the character recognition operation of the identification symbol 10 thereafter.

In this embodiment, when searching and scanning an image,
Although the outer peripheral positions of the pair of partial images are detected, the inner peripheral positions may be the same, or the barycentric position of each partial image on the scanning line may be used.

[0019]

According to the present invention, the center position of each optical disk can be detected with a simple mechanism having an accuracy of such that the ring-shaped mirror surface portion of the optical disk only needs to enter the imaging visual field. , It is a basis for recognizing the identification symbol with high accuracy.

[Brief description of drawings]

FIG. 1 is a plan view of an optical disc according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating a reflected light image of a ring-shaped mirror surface portion of an optical disc.

FIG. 3 is a diagram illustrating a method of calculating center coordinates of a ring-shaped reflected light image.

FIG. 4 is a schematic configuration diagram when the center position detecting method of the present invention is implemented.

FIG. 5 is a perspective view illustrating a conventional center position detecting method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Optical disc 12 Ring-shaped mirror surface portion 120 Reflected light image of ring-shaped mirror surface portion 2 Table 3 Imaging means 4 Center detection device

Claims (3)

[Claims] 1. An optical disk is imaged, a reflected light image from a ring-shaped mirror surface portion by a reflecting film is cut out from the captured image, and the ring-shaped reflected light image is scanned in plural directions in the X direction to scan each image. The position of the partial images forming a pair is recognized for each line, the midpoint between the partial images is calculated, and the average value thereof is taken as the X-direction center coordinate of the ring-shaped reflected light image. Is scanned in the Y direction for a plurality of lines, the positions of the partial images forming a pair are recognized for each line, the midpoint between the partial images is calculated, and the average value thereof is calculated in the Y direction of the ring-shaped reflected light image. A method for detecting the center position of an optical disc, wherein the center coordinate is detected, and the center coordinate in the X direction and the Y direction is detected as the center position of the optical disc. 2. The method according to claim 1, wherein the X-direction center coordinate is obtained from a value obtained by calculating a midpoint between outer peripheral position coordinates of a pair of partial images for each line. A method for detecting the center position of an optical disc, wherein the Y-direction center coordinates are obtained from the respective calculated midpoints between the outer peripheral position coordinates of a pair of partial images. 3. The method according to claim 1, wherein a plurality of search scans of the ring-shaped reflected light image in the X direction and the Y direction are performed near the center of the ring-shaped reflected light image. A method for detecting the center position of an optical disc, characterized by: