JPH0896077A - Apparatus and method for detecting inclination of symbol string - Google Patents

Abstract

(57) [Summary] [Purpose] In a device for detecting the inclination of a character or symbol string by imaging the character or symbol string, the leftmost (first) or rightmost (last) character in the character or symbol string or Even if there are a plurality of same symbols, it is possible to accurately detect the inclination of a character or symbol string by referring to the first and last symbols of the symbol or character string. [Structure] The first and last characters of the character string are searched from the image data of the character string, and the part with a high degree of matching with a predetermined character pattern is recognized as the existing part of the character string, and the first character in the recognized character string is detected. And the inclination of the symbol string is detected based on the last character. At this time, when a plurality of first or last characters are present in the character string, the end point position of the character string is selected and the inclination of the character string is detected based on this, so the accuracy of inclination detection is improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus and a method for detecting the inclination of a symbol string for inspecting the appearance of the symbol string written on the object from the imaged data of the object.

[0002]

2. Description of the Related Art Conventionally, for example, in order to perform a visual inspection such as whether a lot number of a product is correctly written, a symbol string attached to an object is imaged and how it comes into the image pickup screen. There is known a device and a method for detecting a tilt of a symbol string from image data of an unknown symbol string, correcting the inclination of the symbol string, and inspecting the symbol by correcting it to a horizontal position. The method for detecting and correcting the inclination of the symbol string in this apparatus and method will be described below.

The concept of a conventional symbol string inclination detection and correction method will be described with reference to FIG. First, as a pre-setting step, several types of patterns such as characters and symbols to be inspected are stored. At that time, in consideration of the fact that the object is inclined at the time of inspection, a plurality of inclined patterns are stored. In this example, “1, 2, 3, ...” Is used as the pattern character, and the pattern as shown in FIG. 1A is stored. Furthermore, when the character strings are arranged from left to right in order to obtain the inclination of the object itself or the inclination of a string of characters or symbols (hereinafter referred to as a character string), the leftmost character and the rightmost character are arranged. Enter. In this example, it is assumed that they are "1" and "3", respectively.

Next, as an inclination detecting step, as shown in FIG. 1B, the screen is scanned to find a portion having a high degree of coincidence with the pattern stored in the preset setting. As a result, the approximate position where each symbol of the symbol string “1, 2, 3” exists on the screen can be known. Since the inclination angle of the pattern of the character has a discontinuous value, it does not always match the character of the object to be inspected. Next, as shown in FIG. 1C, the center coordinates of the leftmost and rightmost characters that have been input before the inspection, here, the characters “1” and “3” are obtained, and the center coordinates of the respective characters are calculated. The inclination angle of the entire character string with respect to the horizontal direction is calculated from the straight line connecting the two. Finally, as a visual inspection step, as shown in FIG. 1D, the contents of the image memory are tilted by affine transformation according to the tilt angle found in the tilt detection step, and matching with the character pattern is found again. The test result.

[0005]

However, in the above-mentioned conventional method, when there are a plurality of designated leftmost or rightmost characters in the character string in the character string inclination detection step, the inclination angle is calculated. It is uncertain whether or not the character to refer to is the leftmost and rightmost characters that have been input. For example, as shown in FIG. 2, the leftmost character "1" is not a problem, but the rightmost character ""3" is duplicated in the character string, and it becomes uncertain which "3" is used for inclination detection. In such a case, when the leftmost character and the rightmost character that appears next are selected, the straight line connecting the centers of these characters becomes short, and the accuracy of the obtained tilt angle deteriorates.
Therefore, the horizontal correction of the symbol string is not strictly performed, and the appearance inspection may be uncertain.

The present invention has been made to solve the above problem, and when detecting the inclination of a character or symbol string, the leftmost (first) or rightmost (last) of the character or symbol string is detected.
Even if there are multiple characters or symbols that are the same as above, be sure to refer to the first character or symbol and the last character or symbol among them to calculate the tilt angle of the object, and improve the accuracy of the required tilt angle. It is an object of the present invention to provide a symbol string inclination detecting device and method capable of performing the inclination detection.

[0007]

In order to achieve the above-mentioned object, the invention of claim 1 images a symbol string described on an object,
In a symbol string inclination detecting device for detecting the inclination of a symbol string from the imaged data, a pattern storage means for designating the first and last symbols of the symbol string and storing the pattern, and the image data to be stored in the pattern memory means. Sequence detecting means for detecting a position having a high degree of coincidence with the generated pattern as the position of the symbol sequence, and inclination for detecting the inclination of the symbol sequence from the first and last symbols of the symbol sequence detected by the symbol sequence detecting means. A detecting means, the inclination detecting means, when a plurality of first or last symbols stored in the pattern detecting means are present in the symbol string, and an end point of the symbol string position detected by the symbol string detecting means. Is selected, and the inclination of the symbol string is detected based on the symbol located at the end point.

According to a second aspect of the present invention, in the structure of the first aspect, when the inclination detecting means has a plurality of first and last symbols stored in the pattern detecting means in a symbol string, The symbol located at the rightmost end or the leftmost end is selected from the plurality of symbols, and the inclination of the symbol string is detected based on the position of the selected symbol.

According to a third aspect of the present invention, in the structure of the first or second aspect, the pattern storage means has
The pattern of symbols at a plurality of angles is stored.

Further, the invention of claim 4 is a data correcting means for correcting the imaging data based on the inclination of the symbol string detected by the symbol string inclination detecting device according to any one of claims 1 to 3. And a checking means for checking the symbol string based on the data corrected by the data correcting means.

According to a fifth aspect of the present invention, in a symbol string inclination detecting method for imaging a symbol string written on an object and detecting the inclination of the symbol string from the imaged data, the first and last symbols of the symbol string are detected. A step of specifying and storing the pattern, a step of detecting, from the imaging data, a position having a high degree of coincidence with the stored pattern as a position of the symbol string, and the symbol from the first and last symbols of the detected symbol string. And a step of detecting the inclination of the symbol string, and in the step of detecting the inclination of the symbol string, when there are a plurality of first or last symbols in the symbol string, the position that is the end point of the detected symbol string position is set. It is a method for detecting the inclination of a symbol string, which comprises selecting and detecting the inclination of the symbol string based on the symbol located at the end point.

[0012]

According to the symbol string inclination detecting device of the first aspect,
The symbol string detecting means searches the image data of the symbol string for the first and last symbols of the symbol string stored in the pattern storing means, and recognizes a portion having a high degree of coincidence as an existing portion of the symbol string. The inclination detecting means detects the inclination of the symbol string based on the first and last symbols of the recognized symbol string. At this time, when a plurality of first or last symbols stored in the pattern detecting means are present in the symbol string, the inclination detecting means selects the end point position of the symbol string detected by the symbol string detecting means, and selects the selected position. The inclination of the symbol string is detected based on the coordinates. Therefore, the accuracy of tilt detection is improved.

According to the tilt detecting device of the second aspect,
The inclination detecting means selects the symbol located at the rightmost end or the leftmost end among the same plurality of symbols as the first or last symbol, so that even if there are a plurality of first or last symbols in the symbol string,
Inclination can be detected with high accuracy.

According to the tilt detecting device of claim 3,
Since the pattern storage means stores the symbol patterns at a plurality of angles, the symbol string can be detected accurately.

Further, according to the position shift inspection apparatus of the fourth aspect, the data correcting means is based on the inclination of the symbol string detected by the symbol string inclination detecting apparatus according to any one of the first to third aspects. The imaging data is corrected to a horizontal position by the inspection means, and the inspection means inspects the symbol from the symbol string data corrected by the data correction means. Therefore, the appearance inspection of the symbol attached to the object can be performed accurately.

According to the symbol string inclination detection method of claim 5, when a plurality of first or last symbols of the symbol string are present in the symbol string, the end point position of the symbol string is selected and the selected end point is selected. The inclination of the symbol string is detected based on the symbol located.
As a result, it is possible to prevent the symbol referred to for detecting the inclination from being mistakenly recognized, and to detect the inclination of the symbol string with high accuracy.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to the drawings. In the symbol string inclination detection apparatus and method of the present invention,
At the stage of detecting the inclination of the symbol string shown in FIG.
When there are multiple symbols in the symbol string that are the same as the first or last symbol specified in the pre-setting stage, misidentification is prevented.
That is, in the case as shown in FIG. 2, the symbol string “1”
The first symbol "1" and the last symbol "3" of "3" and "3" are correctly recognized. Figure 3
Will be described with reference to. FIG. 3 shows a procedure for selecting both end points (the rightmost end and the leftmost end) of the symbol string when the same symbol is present in the character string when searching the first and last symbols in the symbol string.

In FIG. 3, first, the leftmost character of the first designated symbol, that is, the symbol string is searched (S
1) After that, it is judged whether or not the leftmost symbol is found (S2). If a plurality of the leftmost symbols are found (YES in S2), the symbol located at the minimum x coordinate of the symbol string, that is, the leftmost symbol. The located symbol is adopted as the first symbol (S3). S2
If more than one is not found in S2 (NO in S2), and S3
After the processing of (1), the process proceeds to S4, and this time, the last symbol designated in advance, that is, the rightmost symbol of the symbol string is searched (S4), and it is determined whether a plurality of symbols have been found (S5).
If a plurality of symbols are found (YES in S5), the symbol located at the maximum x coordinate of the symbol string, that is, the symbol located on the far right is adopted as the final symbol (S6), and the process is terminated. S5
If a plurality of items are not found in, the process is terminated (NO in S5).

As described above, when a plurality of the same symbols as the designated first or last ones as shown in FIG. 2 are present in the symbol string, the last symbol "3" is included in the symbol string in the conventional method. It is uncertain which "3" is recognized as the last symbol, but in the apparatus and method of the present invention, the "3" at the coordinate position having the largest x coordinate among the overlapping "3" s.
Is adopted so that it can be recognized correctly. Accordingly, it is possible to improve the accuracy of detecting the inclination of the symbol string, which will be described later, and detecting the inclination of the symbol string in the inspection device.

Further, if a duplicate of the first symbol is found in S3 in the procedure of FIG. 3, the symbol having the minimum x coordinate of the symbol string is adopted, and in S6 in the procedure of FIG. 3, the last symbol is adopted. If a duplicate symbol is found, the symbol with the maximum value of the symbol string is adopted, but as another method, in S3, the first symbol is compared with the duplicate symbol and the maximum value is compared. The rightmost one may be selected as the first symbol, and the last symbol may be compared with the overlapping symbol in S6 to select the leftmost symbol. further,
In the procedure of FIG. 3, the inclination of the symbol string is in the range of −90 ° to 90 °, and the first and last symbols are detected, that is, only the x coordinate is detected, but the step of detecting the y coordinate is also performed. If added, the first and last symbols can be recognized no matter how the symbol string is inclined by 360 °.

FIG. 4 shows a schematic structure of a positional deviation correcting and inspecting apparatus to which the above-mentioned method is applied. The camera 1 images the symbol string attached to the object and outputs a video signal.
The A / D converter 2 converts the video signal from the camera 1 into a digital signal. The image memory 3 stores the digitally converted image data. The input device 4 is composed of a keyboard or the like, and specifies the first and last symbols of a symbol string to be inspected by searching, that is, cuts out a registered pattern. The pattern storage unit 5 stores a registered pattern of symbols to be inspected, interval data of inspected symbol strings, and the like, and the pattern of symbols to be inspected in advance is obtained by image data of the image captured by the camera 1. You just have to enter and register.

The search processing unit 6 constitutes a symbol string detecting means and searches the image data in the image memory 3 for a symbol string designated by the pattern storage unit 5. The tilt angle detection unit / positional deviation correction unit 7 constitutes a tilt detection unit and a correction unit, recognizes the first and last symbols of the symbol string detected by the search processing unit 6, and detects the inclination of the symbol string. ,Also,
The symbol string is rotated to a horizontal position according to the tilt angle, and the corrected data is registered in a predetermined area of the image memory 3. The inspection unit 8 compares the image data registered in the image memory 3 corrected by the positional deviation correction unit 7 with the pattern stored in the pattern storage unit 5 to determine whether or not the symbol is correctly added. It is something to inspect. That is, since this inspection is performed by obtaining the degree of coincidence between the image data after the positional deviation correction and the symbol string pattern without inclination, the inspection accuracy can be improved. The D / A converter 9 converts the image data in the image memory 3 into analog data. The display unit 10 outputs and displays the data of the image memory 3 and the inspection result of the inspection unit 8. The method for detecting the inclination of the symbol string shown in FIG. 3 is performed by the search processing unit 6 and the positional deviation correction unit 7.

Next, the symbol search process (S in FIG. 3) of the positional deviation correcting and inspecting apparatus constructed as described above is performed.
1, S4) will be described in detail with reference to FIG.
FIG. 5 corresponds to the subroutine of S1 and S4 in FIG. 5, in the present process, first, a threshold value of the degree of coincidence between the symbol string detected in the search process and the image data is set (S10), and then the symbols stored in the pattern storage unit 5 are set. An angle of a symbol (hereinafter, referred to as a model) designated in advance from the pattern is set to an initial value, that is, a horizontal position (S11), and the position of this model is aligned with the upper left of the screen defined by the image data (S12). The degree of coincidence is measured in this state (S13).

Next, it is judged whether the measured coincidence is greater than or equal to the threshold set in S10 (S14). If the coincidence is greater than or equal to the threshold (YES in S14), the leftmost model is searched. If possible, the position coordinates are stored (S15),
Proceed to S16. If the degree of coincidence is less than or equal to the threshold value in S14 (NO in S14), the process proceeds to S16 without processing S15. In S16, it is determined whether or not the degree of coincidence has been measured at all positions of the image data, and if not measured at all positions (NO in S16), the model set in S11 is shifted by one pixel on the screen ( S17), and the processes of S13 to S17 are repeated until the degree of coincidence is measured for all the positions. If it is determined in S16 that the degree of coincidence has been measured at all positions (YES in S16), then it is determined whether or not the search has been performed in all model angles (S18), and the search is performed in all angles in S18. If not (NO in S18), the model angle is changed (S19), the process returns to S12, and if all model angles are searched in S18 (YES in S18),
The process ends. In the above procedure, if a plurality of locations where the degree of coincidence is greater than or equal to the threshold value are detected in S14, a plurality of position coordinates are stored in S15.

By performing the above-described processing of FIGS. 3 and 5, it is possible to accurately recognize the first (leftmost) and last (rightmost) symbols (characters) of the symbol string, and to identify the center of these symbols. The inclination of the symbol string can be accurately detected from the equation for obtaining the inclination of the symbol string shown in FIG. 6 based on the coordinates. Further, the content of the image memory 3 is rotated based on the detection of the inclination of the symbol string, for example, by an affine transformation formula as shown in FIG. 7, and the degree of coincidence of the symbols is as shown in FIG. It suffices to check using a matching expression. In this way, it is possible to improve the performance of the recognition of the symbol attached to the object and the appearance inspection. The methods shown in FIGS. 7 and 8 are merely examples, and the methods are not limited to these.

The present invention is not limited to the configuration and method of the above-described embodiment, and various modifications can be made. A plurality of inclined symbol patterns as shown in FIG. 1 (a) are based on image data captured in advance. It can be obtained by the operator setting various attributes from the input device 4. However, if several kinds of rotation patterns are automatically obtained with respect to the symbol pattern of one angle, the labor of the operation can be saved, and By finely dividing the angle of rotation, it is possible to reliably detect a character that matches a tilted symbol. Further, before the inspection, the symbols or characters to be inspected at the beginning and end of the symbol or character string to be inspected are specified from the input device 4 and input, but at that time, the first symbol or character and the A symbol or a character may be designated and registered.

If there are a plurality of character strings to be inspected, the plurality of character strings are formalized in advance as shown in FIG. 9, and the format number is input from the input device 4 before the inspection. The last character may be registered. That is, when the format "A-1" in FIG. 9 is input, the character strings "A, B, C" can be automatically inspected. The first letter and the last letter at that time are "A"
And "C" are automatically registered.

[0028]

As described above, according to the apparatus and the method of claims 1 and 5, when the inclination of a symbol string is detected, a plurality of symbols identical to the designated first or last symbol exist in the symbol string. However, since the end point position of the symbol string is selected and used as the reference symbol for tilt detection, the first and last symbols of the symbol string can be reliably selected and detected without misidentifying the first or last symbol. Therefore, the accuracy of the inclination angle of the symbol string can be improved. Further, according to the inclination detecting device of the second aspect, the inclination detecting means selects the symbol located at the rightmost end or the leftmost end among the same plurality of symbols as the first or last symbol, so that the accuracy is higher. The inclination of the symbol string can be detected. Further, according to the inclination detecting device of the third aspect, since the pattern storing means stores the symbol patterns at a plurality of angles, it is possible to reliably detect the symbol to be inspected. Further, the symbol string position deviation inspection device according to claim 4 corrects the symbol string to a horizontal position based on the tilt angle detected by the tilt detection device according to any one of claims 1 to 3, Since the symbols are inspected, the appearance of the symbol string can be accurately inspected.

[Brief description of drawings]

FIG. 1 is a diagram showing a method procedure of a conventional character string inclination detection.

FIG. 2 is a diagram showing a state in which the last character specified in a character string whose inclination is to be detected overlaps.

FIG. 3 is a flowchart showing a processing procedure for detecting first and last characters according to an embodiment of the present invention.

FIG. 4 is a block diagram showing a schematic configuration of a misalignment correction and inspection device equipped with a character string inclination detection device according to an embodiment of the present invention.

5 is a flowchart showing a procedure for detecting character candidates located at the leftmost and rightmost positions in FIG.

FIG. 6 is a diagram for explaining an expression for obtaining the inclination of a character string.

FIG. 7 is a diagram for explaining an affine transformation formula.

FIG. 8 is a diagram for explaining matching.

FIG. 9 is a diagram illustrating a method of designating first and last characters according to another embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 camera 3 image memory 4 input device 5 pattern storage unit (pattern storage unit) 6 search processing unit (symbol string detection unit) 7 position shift correction unit (tilt detection unit, correction unit)

Claims (5)

[Claims] 1. A symbol string inclination detecting device for imaging a symbol string written on an object and detecting the inclination of the symbol string from the imaged data, wherein the first and last symbols of the symbol string are designated and the pattern is stored. Pattern storage means, a symbol string detection means for detecting, from the imaged data, a position having a high degree of coincidence with the pattern stored in the pattern storage means as the position of the symbol string, and the symbol string detected by the symbol string detection means. A tilt detecting means for detecting the tilt of the symbol string from the first and last symbols of the symbol string, wherein the tilt detecting means has a plurality of first or last symbols stored in the pattern detecting means in the symbol string. In addition, the position of the symbol string position detected by the symbol string detecting means is selected as an end point, and the inclination of the symbol string is detected based on the symbol located at the end point. That symbol column slope detection device. 2. The inclination detecting means selects a symbol located at the rightmost end or the leftmost end of the plurality of symbols when a plurality of first and last symbols stored in the pattern detecting means are present in the symbol string. Then, the symbol string inclination detection device according to claim 1, wherein the inclination of the symbol string is detected based on the position of the selected symbol. 3. The symbol string inclination detection device according to claim 1, wherein the pattern storage means stores symbol patterns at a plurality of angles. 4. A data correction means for correcting imaging data based on the inclination of a symbol string detected using the symbol string inclination detection device according to claim 1, and the data correction means. An inspection device for inspecting a symbol string position based on the corrected data. 5. A symbol string inclination detection method for imaging a symbol string written on an object and detecting the inclination of the symbol string from the imaged data, wherein the first and last symbols of the symbol string are designated and the pattern is stored. And a step of detecting a position having a high degree of coincidence with the stored pattern as a position of the symbol string from the imaging data, and a step of detecting the inclination of the symbol string from the first and last symbols of the detected symbol string. And, in the step of detecting the inclination of the symbol string, when there are a plurality of first or last symbols in the symbol string, select a position that is the end point of the detected symbol string position, A method for detecting the inclination of a symbol string, which comprises detecting the inclination of a symbol string based on a symbol located.