JPS59172244A - Notch detecting process of disc - Google Patents

Abstract

PURPOSE:To detect the notch of a disc rapidly and accurately by a method wherin a curvature fluctuation on the circumference of a disc at a specified distance is pursued after along the periphery of the disc to detect a straight line part out of circular part. CONSTITUTION:A marking peripheral image element detector 7 detects an optional peripheral image element P0 out of peripheral image elements on the circumference of a disc 2. Next a peripheral equidistant image element detector 8 as a means to detect two peripheral image elements P1 and P2 at a specified distance (r) from the reference image element P0 outputs location data of said elements P1 and P2 from the reference image element P0. A straight line discriminator 9 calculates a supplementary angle delta met by segments P0-P1 and P0-P2 in terms of the location data on three image elements comprising the reference image element P0, said peripheral equidistant image elements P1 and P2 to output a true datum in case the image elements P0, P1 and P2 are on a straight line with the supplementary angle delta=0 while a final processor 10 discriminates the direction of a notch of the straight line part i.e. the attitude of the disc 2. When the datum is false, said output may be forward to a marking image element shifting processor 11 to set up a new marking image element for detecting a truly straight line part.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides image information obtained by imaging an object used in the manufacture of semiconductor devices, which consists of a straight part and a circular part of a disc-shaped body having a straight notch. More specifically, the present invention relates to a method of detecting the direction of the straight line portion.

When reading an identification mark of a semiconductor element on a disc-shaped body, it is necessary to know the precise direction of the notch, which serves as a reference line of the disc-shaped body. Conventionally, in order to grasp the reference line of this disc-shaped body, a linear notch L was used as shown in Figure 1.
The image pickup device 3 captures the disk-shaped body 2 having The binary image information output from the pre-processing section 4 is converted into value image information, and the entire binary image information is taken into the storage section 5.The posture detection processing section 6 calculates the disc shape from the binary image information taken into the storage section 5. Calculate the center of the body 2, match the center of the circular dictionary pattern with the same diameter as the disc-shaped body 2, and find the mismatched part corresponding to the notch 1 ( The direction of the straight part of the notch 1 is determined by the mismatching method.

However, in this notch detection method, the processing in the posture detection processing unit 6, that is, the processing for calculating the entire center of the disc-shaped body 2, and the processing for detecting mismatching between the disc-shaped body 2 and the dictionary pattern are required. In both cases, the processing requires a huge amount of processing time and requires a huge amount of processing time, as it involves distinguishing between all pixels on the screen whether they are centered or not, and whether or not they are mismatched. The disadvantage was that it took a lot of time.

In addition, since various patterns for forming semiconductor elements are written on the disc-shaped body 2, the surface pattern of the disc-shaped body 2 becomes noise during binary image conversion after imaging, and the disc-shaped body 2 It was difficult to accurately calculate the center position of the shaped body 2.

In order to eliminate the above-mentioned drawbacks, the present invention detects a straight part from a circular part by tracing the change in curvature of the outer periphery of the disc-shaped body at regular intervals along the periphery of the disc-shaped body. It is an object of the present invention to provide a method for detecting notches in a disc-shaped body, which detects the notches at high speed and accurately.

The present invention achieves this object by capturing an entire disk-shaped body having a linear notch in a part of its outer periphery, converting the output signal of this imaging device into binary image information by a preprocessing unit, and then storing the image information in a storage unit. In the method for detecting a notch in the disc-shaped body (using the binary image information stored in While tracking the peripheral image, two peripheral pixels located at a certain distance from the pixel of interest are found, and by finding that these three peripheral pixels are on a straight line, a notch in the disc-shaped body is detected. It is characterized by

In principle, the notch detection method according to the present invention, as shown in FIG.
Two peripheral pixels Pl are equidistant r from the peripheral pixel of interest (pixel of interest) Po.

The angle P formed by P, , Po, is represented by the supplementary angle 6 of P, and the supplementary angle δ is detected at every fixed distance r along the circumference of the disc-shaped body 20, and when δ=0, that is, the peripheral pixel P,
, Po, and P are straight lines to find the direction of the straight line portion of the circular plate-shaped body 2.

Hereinafter, the present invention will be described in detail with reference to FIGS. 4 and 5 as well as FIG. 3. In FIG. 4, the peripheral pixel of interest detection unit 7 is means for finding an arbitrary peripheral pixel (pixel of interest) Po among the peripheral pixels existing on the outer periphery of the disc-shaped body 2.

Specifically, for example, pixels are detected while horizontally scanning from the center pixel S1 at the left end of the imaging screen to the center pixel S2 at the right end, and binary image information corresponding to the screen other than the disk-shaped body 2 is detected. The first point of change at which the binary image information drawn on the disc-shaped body 2 changes from OFF to ON is found and the position information of that pixel (target pixel) Po is output.

Next, the peripheral equidistant pixel detection unit 8 detects two peripheral pixels P existing at a constant distance r from the pixel of interest PO.

and Pie, the peripheral equidistant pixel P1 . Output the position information of P2.

Specifically, as shown in FIG.
Create a circular pattern consisting of pixels located at a certain distance r from
The peripheral equidistant pixel P1. Find P. These peripheral pixels P, , P.

The position can be determined easily and immediately because the central pixel of interest Po is determined and a circular pattern is also set.

The straight line determining unit 9 selects the pixel of interest Po and the peripheral equidistant pixel P1.
* Based on the three pixel position information consisting of Pl, calculate the supplementary angle δ formed by the line segment between Po and P and the line segment between Po and Pl, and the supplementary angle δ becomes 0, and the pixels P, , P, , Pl
When is on a straight line, it outputs true information, and when it is a supplementary angle δNO and is on a straight line, it outputs false information @. When the true information is output from the straight line determining unit 9, the termination processing unit 10 obtains the direction of the notch in the straight line portion, that is, the attitude of the disc-shaped body 2.

When the output from the straight line determining section 9 is false information, this output reaches the pixel of interest movement processing section 11.

The pixel of interest movement processing unit 11 selects a pixel P based on false information. ,
Since p, , p, is not a straight line part, this is a means of setting a new pixel of interest in order to further search for a straight line part. Here, when determining a new pixel of interest, among the pixels that are found to be not in a straight line, the peripheral equidistant pixels Pt, Pg
y as a new pixel of interest. That is, the pixel of interest movement processing section 11 outputs Pl, which is a new pixel of interest, or pixel position information of Pl. Whether to use pixel Pl or Pl 4 as the pixel of interest depends on whether the circumference of the disc-shaped object is tracked clockwise or counterclockwise, and either can be selected. It is possible. Furthermore, this method of determining the pixel of interest is that, except for determining the first pixel of interest that is scanned from the edge of the screen, one of the intersections between the circular pattern and the peripheral pixels is set as the pixel of interest. First, all pixels of interest may be scanned from the edge of the screen to narrowly determine the pixels of interest.

The above method can be used for any object that has a linear cutout in a disc-shaped body, such as a semiconductor substrate, and can also be used when the disc-shaped body is located at an arbitrary position on the screen. It also has the feature that the direction of the notch can be detected at high speed.

As explained above, the present invention makes effective use of the characteristics of an object such as a one-handed conductor board whose shape is composed of a circular part and a straight part, and allows It has specificity in determination, and does not require a large amount of processing such as calculating the center of a disc-shaped object or detecting pattern mismatching, as required in the past, and can quickly and accurately determine the direction of a notch from an image of a disc-shaped object. Can be detected. Therefore, it can be used to detect the attitude of a moving disc-shaped body, and the same method can be used even if the size of the object changes.

[Brief explanation of drawings]

Fig. 1 is a configuration diagram for explaining a conventional notch detection method, Fig. 2 is an explanatory diagram of an example of binary image information corresponding to a screen, Fig. 3 is a detailed explanatory diagram of the present invention, and Fig. 4 5 is a circuit block diagram illustrating an example of the notch detection method of the present invention, and FIG. 5 is an explanatory diagram showing an example of a circular pattern. In the figure, 3 is an imaging device, 4 is a preprocessing unit, 5 is a storage unit, 7 is a peripheral pixel of interest detection unit, 8 is a peripheral equidistant pixel detection unit, 9 is a straight line determination unit, 10 is an end processing unit, 11 is a pixel of interest movement processing unit, Po is a pixel of interest, and Pl and Pl are peripheral equidistant pixels. Patent applicant Nippon Telegraph and Telephone Public Corporation representative Patent attorney Shibu Mitsuishi (and one other person)

Claims (3)

[Claims] (1) A disk-shaped object containing a linear notch on a part of its outer periphery is captured by an imaging device, and the output signal of the imaging device is converted into binary image information by a preprocessing section and stored in a storage section. In the method of detecting a notch in the disc-shaped body using binary image information from the storage unit, one of the peripheral pixels of the disc-shaped body is set as a pixel of interest, and this pixel of interest is used to detect the notch of the disc-shaped body. The present invention is characterized by detecting a notch in a disc-shaped body by finding two peripheral pixels located at a certain distance from the pixel of interest while tracking the above-mentioned pixel, and finding that these three peripheral pixels are on a straight line. A method for detecting notches in disc-shaped objects. (2) In the method for detecting a notch in a disc-shaped body according to claim 1, when finding two peripheral pixels located at a certain distance from the pixel of interest, in advance, from a pixel located at a certain distance from the pixel of interest, A circular pattern is constructed, the center of the circular pattern is aligned with the pixel of interest, and two peripheral pixels are found by finding the intersection between the pixel of this circular pattern and the peripheral pixel of the disc-shaped object. A method for detecting a notch in a disc-shaped object. (3) In the method for detecting a notch in a disc-shaped body according to claim 1 above, in identifying the pixel of interest until it is found that the three peripheral pixels are on a straight line, A method for detecting a notch in a disc-shaped body using one of two peripheral pixels at a distance of as the next pixel of interest.