JPH01181165A - Tilt detecting device - Google Patents

Abstract

PURPOSE:To improve the tilt calculating accuracy and to detect even the tilt of a complicated pattern by obtaining the density distribution signals in response to the angles for both subject and standard patterns and calculating a tilt angle from the mutual correlative function between both patterns. CONSTITUTION:A photoelectric transformation scanner 1 is scanned by a synchronizing signal 16 of a synchronizing generating circuit 15 and an input picture 2 is read out and converted into a digital picture 4 of a multiple level via an A/D converter 3. A density distribution calculating circuit 5 calculates the mean value of the picture 4 in accordance with its angle formed to a center position and obtains a density distribution signal 6 to store this signal into a subject pattern memory circuit 8 in case the scanning position set on the picture 4 is kept within a fixed distance from the center position detected preliminarily. While a standard pattern is also stored in a standard pattern memory circuit 7. Then a mutual correlative function calculating circuit 11 calculates a mutual correlative function 12 based on the signals 9 and 10 received from both circuits 7 and 8 respectively. Thus a tilt signal 14 which secures the optimum value is calculated.

Description

[Detailed Description of the Invention] [Industrial Field of Application] The inclination detection device of the present invention, in particular, detects the inclination of a target pattern read out by scanning a standard pattern stored in advance with a one-dimensional electric conversion scanner. Regarding the desired tilt detection device.

[Conventional technology]

As a conventional technology, for example, M.L.P. Baird (+
d, h, t3aird) is an app'y
-'/-1-op Computer Vision to Automated IC Chip Manufacture (an application of Comput
Ter fision to Automated IC
Chip Manufacture) was published under the title of Plonde Ink IIv-De Internasi Shoulder Narugeot Conference-On Pattern Ringenin! l
7 (Proc, 3rd Int JointConf
on Pattern Recognition)
There is a technique for detecting the tilt of an IC chip, as announced in 1976 on pages 3 to 7.

Conventional tilt detection technology performs edge detection processing using a 3 x 3 window on the input digital image when the directional distribution of the edges of the target pattern is limited to 08 and 90 degrees. The distribution was obtained, and the deviation between the value and the limited distribution Oo and 90° as described above was obtained and the slope was calculated.

[Problem that the invention seeks to solve]

In the conventional tilt detection technology described above, since the edge direction distribution is used by edge detection processing using a 3×3 window, the accuracy of calculating the tilt of the target pattern is poor, and there are restrictions on the edge direction distribution of the target pattern. Therefore, there is a drawback that it is impossible to detect the inclination of a plurality of patterns.

[Means for solving problems]

The tilt detection device of the present invention includes an original 1 conversion scanner that scans a pattern to be detected for tilt, a synchronization signal generation circuit for controlling the photoelectric conversion scanner, and a multiplex image detected by the original i, ilc conversion scanner. The scanning position on the digital image is determined based on the output signal of the A/D conversion circuit for converting to a digital image of the 1st level digital image and the synchronization signal generation circuit, and the scanning position is within a certain distance from the center position detected in advance. a density distribution calculation circuit that calculates the average value of the digital image according to the angle formed by a point with respect to the center position, and obtains an 8-degree distribution with respect to the angle;

There is a target pattern storage circuit for storing the calculated density distribution, a standard pattern storage circuit for storing the density distribution for angles calculated in advance by performing the same process as described above for the standard pattern, and a cross-correlation calculation circuit that calculates a cross-correlation function using the output value of the target pattern storage circuit and the output value of the standard pattern storage circuit;

and a slope calculation circuit that calculates the slope from the position giving the maximum value of the calculated cross-correlation function.

〔Example〕

Next, one embodiment of the present invention will be described in detail with reference to one drawing.

FIG. 1 is a block diagram showing one embodiment of the present invention.

Using the synchronization signal 16 output from the synchronization signal generation circuit 15, the optical conversion scanner 1 is scanned to read out the human image 2, which is further converted into a multilevel digital image 4 by the A/D conversion repair 3. do.

The density distribution calculation circuit 5 calculates the scanning position on the digital image 4 based on the synchronization signal 16, and if the position is within one foot distance from the previously detected center position, it is determined as the center position. The average value of the digital image 4 is calculated according to the angle formed by the digital image 4 to obtain the density distribution with respect to the angle, and the calculated 4-degree distribution signal 6 is stored in the target pattern storage circuit 8.

For the standard pattern, the same processing as above was performed in advance, and the calculated density distribution is as follows.

The standard pattern is stored in the standard pattern storage circuit 7 in advance.

Using the standard pattern signal 9 outputted from the standard pattern storage circuit 7 and the target pattern signal 10 outputted from the target pattern a memory circuit 8, the cross-correlation calculation circuit 11 calculates the cross-correlation function 12. Slope calculation circuit 13
Then, the slope is calculated from the position giving the maximum weight of the calculated cross-correlation function 12, and the slope signal 14 is output.

Next, details of each part will be explained.

FIG. 2 (al, tbl is an explanatory diagram of the operation of the concentration distribution calculation circuit).

Figure 2 1b+ is a digital image 20 created by one person.
It shows how the concentration distribution is determined for points within the concentration distribution calculation area within a certain distance r from the center 23 according to the inclination angle θ.

Further, FIG. 2 1b+ shows the concentration distribution 6 determined by the aforementioned concentration distribution calculation circuit.

FIG. 3 is a professional diagram showing the concentration distribution calculation circuit.

The control unit 30 determines the traveling position based on the input synchronization signal 16, and calculates the distance and angle θ between that position and the pre-registered center position by X-x(.

However, x, y): Scanning position (xOaYo): Center position - 90° θ≦90° Calculated using formulas (1) and (2), and if the distance is smaller than the preset distance r, An angle signal 35 and a control signal 31 are output.

Further, the contents of the table memory section 32 are read out using the angle signal 35 as the address of the memory, and the read memory data 36 is written as the city 1. Under the control signal 31, the digital image 4 is added to the adder 31834, and the added value 33 resulting from the addition is used to update the contents of the table memory section 32 corresponding to the angle signal 35. By sequentially reading out the contents of the table memory section 32 when the processing described above for all human-powered digital images 4 is completed.

A modified distribution signal 6 is obtained.

FIG. 4 tal and tbl are explanatory diagrams of the slope calculation method.

FIG. 4 ta+ shows the density distribution with the standard pattern signal 9 and the target pattern bias +510.

Fbl in FIG. 4 was obtained using the standard pattern signal 9 as a reference. The state of the cross-correlation function 12 with the target pattern signal 10 is shown. The position where the cross-correlation value is maximum.

When calculated by the slope calculating circuit 13, a slope signal 14 is obtained as the amount of deviation τ.

〔Effect of the invention〕

In the tilt detection device of the present invention, instead of performing edge extraction processing using a 3×3 window, a degree distribution signal corresponding to the angle θ is obtained for each of the target pattern and the standard pattern, and roughly Since the tilt angle is calculated from the cross-correlation function, there is an effect that the tilt calculation phase change is good and it is also possible to detect the tilt of a complicated pattern.

[Brief explanation of the drawing]

Figure 1 is a block diagram showing one embodiment of the present invention, Figure 2
a) , (bl is an explanatory diagram of the operation of the concentration distribution calculation circuit. Figure 3 is a professional diagram of the concentration distribution calculation circuit, Figure 4 tal
, tbl is an explanatory diagram of the slope calculation method. l... Original IT conversion scanner, 2... Human image, 3... A/Di conversion circuit, 4...
・Digital image, 5...Concentration distribution calculation circuit,
6... Modified distribution signal, 7... Standard pattern storage circuit, 8... Target pattern storage circuit,
9-.....quasi pattern signal, 10..... target pattern signal, 11..... cross-correlation calculation circuit,
12... Cross-correlation function, 13... Slope calculation circuit, 14... Slope signal, 15...
・Synchronization color code generation circuit, 16...Synchronization signal, 20
...Digital image, 21...Density distribution calculation area, 22...Tilt angle, 23...
- Center, 30... Control section, 31...
Control signal, 32... Table memory section, 33.
...addition; direct. 34...Addition section, 35...Angle signal,
36...Memory data. Agent Patent Attorney Shinkan Uchihara 1 Sensan 2 SenCb) Eveshi〉ira θ 3rd bacterium

Claims (1)

[Claims] a photoelectric conversion scanner that scans a pattern to be detected for tilt;
a synchronization signal generation circuit for controlling the photoelectric conversion scanner; an A/D conversion circuit for converting the image detected by the photoelectric conversion scanner into a multilevel digital image; and an output of the synchronization signal generation circuit. The scanning position on the digital image is determined based on the signal, and the average value of the digital image is calculated according to the angle made with the center position for a point within a certain distance from the center position detected in advance, and the density relative to the angle is calculated. A concentration distribution calculation circuit for determining the distribution, a target pattern storage circuit for storing the calculated concentration distribution, and a standard pattern memory for storing the concentration distribution for angles calculated in advance by performing the same processing as described above for the standard pattern. a cross-correlation calculation circuit that calculates a cross-correlation function using the output value of the stored target pattern storage circuit and the output value of the standard pattern storage circuit, and a position that gives the maximum value of the calculated cross-correlation function. A tilt detection device comprising: a tilt calculation circuit that calculates a tilt.