JPH0535467B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a position detection device, and particularly to a position detection device that detects a positional deviation of a positioning target pattern read out by scanning with a photoelectric conversion scanner.

[Conventional technology]

As for the conventional technology, for example, Kashiwaoka, Ejiri, Sakamoto "Group control transistor assembly system using time-division pattern recognition technology" IEEJ Transactions Vol. 56
-C, no. 1, pp9-16 January 1976, there is a position detection device.

In a conventional position detection device, an input image scanned and read by a photoelectric conversion scanner is converted into a binary image by a binarization circuit, and a specified N×M of the converted binary images is A method is used in which pixels are stored in advance as a standard pattern, the degree of coincidence between the binarized image of the positioning target pattern and the stored standard pattern is sequentially checked, and the position with the highest degree of coincidence is detected. was.

[Problem that the invention seeks to solve]

In the above-mentioned conventional position detection device, the input image scanned by the photoelectric conversion scanner is processed by converting it into a binary image of "0" and "1" at a fixed binary level, so noise is reduced. If the input image changes due to influence or changes in lighting conditions, the binarized image will also change accordingly, so when performing position detection to determine the degree of match with the standard pattern, the detected position may shift or may not be detected. The problem was that it was possible.

[Means for solving problems]

The position detection device of the present invention includes an A/D conversion circuit for converting an image signal read out by scanning with a photoelectric conversion scanner into a multilevel digital image;
A standard pattern memory circuit for storing the converted digital image as a standard pattern, and the contents of the stored standard pattern memory,
An image retrieval circuit for retrieving image signals of a plurality of pre-specified lines, an autocorrelation function calculation circuit for calculating an autocorrelation function for the retrieved image signals, and a memory for storing the calculated autocorrelation function. for calculating respective cross-correlation values between the autocorrelation storage circuit of the positioning target pattern, the output signal of the A/D conversion circuit of the positioning target pattern, the delayed signal of the output signal, and the output signal of the image retrieval circuit. Consists of a cross-correlation calculation circuit and a position detection circuit that calculates the amount of positional deviation from the standard pattern by comparing the calculated cross-correlation value with an autocorrelation function stored in advance in an autocorrelation storage circuit. be done.

〔Example〕

Next, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram showing one embodiment of the present invention. In the figure, an input image 2 scanned and read out by a photoelectric conversion scanner 1 is transmitted to an A/D conversion circuit 3.
The digital image 4 is converted into a multilevel digital image 4.

The digital image 4 is stored as a standard pattern in a standard pattern memory circuit 5, and among the contents 6 of the stored standard pattern memory, image signals of a plurality of pre-specified lines are extracted by an image extraction circuit 7. An autocorrelation function 10 is calculated from the extracted image 8 by an autocorrelation function calculation circuit 9, and the calculated autocorrelation function is stored in an autocorrelation storage circuit 11.

The cross-correlation calculation circuit 12 converts the multilevel digital image 4 of the positioning target pattern converted by the A/D conversion circuit 3 and the delayed signal of the digital image 4 into an image 8 extracted by the image extraction circuit 7. A cross-correlation value 13 is calculated between the two, and each calculated cross-correlation value 13 is calculated based on the content 15 of the autocorrelation storage circuit 11 calculated in advance by the position detection circuit 14.
The amount of positional deviation 16 from the standard pattern is calculated.

Next, details of each part will be explained.

FIG. 2 is an explanatory diagram of the operation of the autocorrelation function calculation circuit. When the input signal 20 is x(k) (k=1 to N), the autocorrelation value when the deviation amount 22 is r is C(τ)=1/N _N 〓 ^k=1 {x(k)−} {x(K−τ)−}
...(1) However, indicates the average value.

It is expressed as Therefore, the autocorrelation function when τ is changed is as shown in FIG.

FIG. 3 shows a block diagram of the autocorrelation function calculation circuit. In the figure, an input signal 30 is input to a subtraction circuit 3.
3 and added to the delay circuit 31, and the delay circuit 3
1, the delayed signal 32 is delayed by a certain delay amount τ.
is applied to the subtraction circuit 33, and in the subtraction circuit 33,
The average value of the input signal is subtracted and input as output signals 34 and 35 to a multiplier circuit 36. This multiplication value 37 is added by an adding circuit 38 and an autocorrelation value 39 is output.

FIG. 4 shows a block diagram of the cross-correlation calculating circuit. In the figure, the output signal of the A/D conversion circuit described above is applied as an input signal 40 to a delay circuit 42 and a subtraction circuit 46. The delay circuit 42 delays the signal by a certain amount and outputs it as a delayed signal 43. The subtracting circuits 44 and 46 subtract the average values and output them as subtracted values 45 and 47.
The image signal 41 extracted from the image extraction circuit described above is applied to a subtraction circuit 48, where the average value is subtracted and output as a subtracted value 49. This subtraction value 49 and the subtraction values 45 and 47 are input to multiplication circuits 50 and 54, respectively, and output as multiplication values 51 and 55. These values are input to addition circuits 52 and 56, and cross-correlation values 53 and 57 are input. are calculated respectively.

FIG. 5 is an explanatory diagram of the operation of the position detection circuit. In the figure, the autocorrelation function 60 previously stored in the autocorrelation storage circuit is compared with the cross-correlation value calculated by the above-mentioned cross-correlation calculation circuit, and a matching position 61 is determined, and the amount of deviation at this time is calculated. 63, the positional deviation amount is calculated.

〔Effect of the invention〕

In the position detection device of the present invention, two of "0" and "1" are used.
Instead of converting to a digitized image and processing it, it is converted to a multilevel digital image and positioning is performed based on cross-correlation values, so changes in the input image due to the influence of noise or fluctuations in lighting conditions are avoided. This has the effect that positioning is possible without being affected by

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing one embodiment of the present invention;
2 is an explanatory diagram of the operation of the autocorrelation function calculation circuit shown in FIG. 1, FIG. 3 is a block diagram of the autocorrelation function calculation circuit shown in FIG. 1, and FIG. 4 is a cross-correlation calculation circuit shown in FIG. 1. FIG. 5 is an explanatory diagram of the operation of the position detection circuit shown in FIG. 1. 1...Photoelectric conversion scanner, 2...Input image, 3
...A/D conversion circuit, 4...Digital image, 5
... Standard pattern memory circuit, 6 ... Contents of standard pattern memory, 7 ... Image retrieval circuit, 8 ...
... Extracted image, 9 ... Autocorrelation function calculation circuit, 10 ... Autocorrelation function, 11 ... Autocorrelation storage circuit, 12 ... Cross correlation calculation circuit, 13 ... Cross correlation value, 14 ... Position detection Circuit, 15...Contents of autocorrelation memory circuit, 16...Amount of positional deviation, 20
... Input signal, 21 ... Delay signal, 22 ... Displacement amount, 30 ... Input signal, 31 ... Delay circuit, 32
... Delay signal, 33 ... Subtraction circuit, 34 ... Subtraction value, 35 ... Subtraction value, 36 ... Multiplication circuit, 37 ...
... Multiply value, 38 ... Addition circuit, 39 ... Autocorrelation value, 40 ... Input signal, 41 ... Image signal, 42
... Delay circuit, 43 ... Delay signal, 44 ... Subtraction circuit, 45 ... Subtraction value, 46 ... Subtraction circuit, 47
... Subtraction value, 48 ... Subtraction circuit, 49 ... Subtraction value, 50 ... Multiplication circuit, 51 ... Multiplication value, 52 ...
... Addition circuit, 53 ... Cross correlation value, 54 ... Multiplication circuit, 55 ... Multiply value, 56 ... Addition circuit, 57
...Cross correlation value, 60...Autocorrelation function, 61...
... Matching position, 62 ... Delay amount, 63 ... Position deviation amount.

Claims (1)

[Claims] 1. An A/D conversion circuit for converting an image signal read out by scanning with a photoelectric conversion scanner into a multilevel digital image, and a standard pattern memory circuit for storing the converted digital image as a standard pattern. An image retrieval circuit for retrieving image signals of a plurality of pre-specified lines from among the contents of the stored standard pattern memory, and an autocorrelation function calculation circuit for calculating an autocorrelation function for the retrieved image signals. and an autocorrelation storage circuit for storing the calculated autocorrelation function, an output signal of the A/D conversion circuit of the positioning target pattern, a delayed signal of the output signal, and an output signal of the image extraction circuit. By comparing the cross-correlation calculation circuit for calculating each cross-correlation value with the autocorrelation function stored in the autocorrelation storage circuit in advance, the amount of positional deviation from the standard pattern A position detection device comprising: a position detection circuit that calculates a position detection circuit.