JPH02161576A - Binary code reader - Google Patents

Abstract

PURPOSE:To accurately and rapidly read out a binary code by sequentially arranging the brightness values of binary codes in the ascending order of the brightness values, finding out respective differences from the sequenced values and binarizing a position indicating the maximum value of the differences. CONSTITUTION:The output of a photoelectric converter 1 for picking up the image of a binary code printed on a semiconductor device and converting the image into an electric signal is converted into a digital signal by an A/D converter 2 and inputted to a block position determining part 3. The determination part 3 finds out the position of a block constituted of codes. The code position in the block is found out by a code position determining part 6 and then the brightness of the code part is found out by a code brightness detecting part 7 as a digitized value. Above operation is repeated by the number of times corresponding to the number of codes forming one block. After rearranging these values in the ascending order, respective differences of these values are found out and a threshold discriminating the existence of a code at the part indicating the maximum value of the differences is found out by a threshold determining part 9. After ending the processing of all the codes, a recognition code is determined by a recognition determining part 8.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a binary code reading device.

[Conventional technology]

FIG. 6 is a block diagram showing a conventional binary code reading device. In the figure, 1 is a photoelectric conversion device;
2 is an A/D converter; 3 is a block positioning unit that positions a block composed of codes; 4 is a block brightness histogram creation unit; 5 is a threshold determining unit that determines a threshold value for the presence or absence of a code; Reference numeral 6 denotes a code positioning section that positions the code within the block, 7 a code brightness detection section that detects the brightness of the code within the block, and 8 a recognition code determination section. Note that the cord positioning section 6. Inside the code brightness detection unit 7 is a block 6 composed of codes.
1 to 66.71 to 76 exist, and in Figure 6, 6 is an example.
I have one. FIG. 2 shows the overall configuration, in which 1 is a photoelectric conversion device, 10 is a recognition device indicated by numerals 2 to 8 in FIG.
1 is a semiconductor wafer, 12 is a lighting device, and 13 is a block consisting of six codes. Further, FIG. 4 shows a block consisting of six codes, 13a to 13c are parts without codes, and 14a to 14c are parts with codes.

Furthermore, Fig. 7 is a code recognition flowchart for explaining the operation of the conventional device, Fig. 8 is a brightness histogram of a block composed of codes with a large difference in brightness, and Fig. 9 is a code recognition flowchart for explaining the operation of a conventional device. 15 is the blackest part, 16 is the whitest part, 17 is the brightness histogram, 18 is the histogram peak of the part without code, 19 is the histogram peak of the part with code, 20 is the presence or absence of code. is the threshold value.

As shown in FIG. 2, the illumination device 12 illuminates the semiconductor device 11 from an oblique direction, and the photoelectric conversion device 1 images the surface of the semiconductor device 11 on which the code to be recognized is printed, and the image is transmitted to the recognition device. Take in at 10. Since the subsequent processing will be performed by the microcomputer, the process will be explained according to the flowchart shown in FIG.

Find the position of the block composed of the code from the image captured by the recognition device 10 (step 21.22),
Next, as shown in Figure 8, a brightness histogram is created from the digitized values of the brightness of the block composed of codes (Step 23), a threshold value for the presence or absence of a code is determined (Step 24), and the code position within the block is determined. , the brightness within the code is detected (steps 25 and 26), and the value obtained by digitizing the brightness of the block for each code is compared with the previously determined threshold, and if the threshold is larger, then If the threshold value is smaller, the part is determined to have no code (step 27), and this flow is performed for all codes of one block (step 28). After all codes are completed, a recognition code is determined based on the code presence/absence result (step 29).

[Problem to be solved by the invention]

Since the conventional binary code reading device is configured as described above, if there is a small difference in brightness between the areas with and without codes, two peaks will appear in the brightness histogram as shown in Figure 9.
Therefore, it is impossible to accurately recognize the code.

The present invention has been made in view of these points, and its purpose is to provide a device that can read binary codes accurately and in a short time.

[Means to solve the problem]

In order to solve such problems, the present invention provides a lighting device that illuminates a binary code surface printed on a semiconductor device from an oblique direction, and a lighting device that illuminates the binary code surface of the semiconductor device illuminated by the lighting device. an A/D converter that converts the brightness into a numerical value from the electrical signal obtained by the photoelectric conversion device;
A block positioning unit that determines the position of a block composed of a binary code in which there is at least one code corresponding to white and one black from the signal output from the converter, and a block positioning unit that performs binarization from the determined position of the block. A code positioning unit that determines the position of the code, a code brightness detection unit that converts the brightness of the determined position of the binary code into a digital value, and a code brightness detection unit that ranks the brightness of the binary code in order of brightness. A threshold determining section is provided which calculates each difference from the numerical values and binarizes the difference at the point where the difference shows the maximum value.

[Effect]

In the binary code reading device according to the present invention, after digitizing the brightness of a block made up of codes and arranging the values in descending order, the presence or absence of a code is determined at the part that indicates the maximum value of each difference. To detect.

〔Example〕

FIG. 1 is a block diagram showing an embodiment of a binary code reading device according to the present invention. In the figure, numeral 9 denotes a threshold value determination unit that determines the threshold value for the presence or absence of a code, and the same or equivalent parts as in FIG. 6 are given the same reference numerals. FIG. 3 is a code recognition flowchart for explaining the operation of the apparatus shown in FIG. 1, and FIG. 5 is an explanatory diagram showing a number line in which numerical values obtained by digitizing the brightness of FIG. 4 are arranged.

FIG. 2 is an overall configuration diagram, and the recognition device 10 in FIG. 2 consists of the components 2, 3, and 6 to 9 in FIG. As shown in FIG. 2, the lighting device 12 illuminates the semiconductor device 11 from an oblique direction.
Illuminates the semiconductor device! The photoelectric conversion device 1 takes an image of the surface on which the code No. 11 to be recognized is printed, and the image is captured by the recognition device 10.The subsequent processing is performed by a microcomputer, so the explanation will be given according to the code recognition flowchart in FIG. .

From the image captured by the recognition device 10, the position of the block composed of codes is determined (steps 31 and 32);
Next, find the position of the code within the block (step 33
), the brightness of the code portion is determined as a digitized value (step 34).

Repeat this for the number of codes forming one block (step 35).Next, after rearranging these numbers on a number line in descending order (see Figure 5), calculate the difference between each one. and find a threshold for distinguishing the presence or absence of a code at the part that indicates the maximum value of the difference (step 36).
, and FIG. 5' as an example, the difference is greatest between code 13a and code 14b. Therefore, the threshold value is (numerical value of code 13a + numerical value of code 14b)/2, and 14b has a larger numerical value than this threshold value.

14C and 14a have codes (step 37),
After all the codes have been completed (step 38), a recognition code is determined (step 39).

Note that although the above embodiment describes the case of reading a code printed on a semiconductor wafer, the same effect as in the above embodiment can be obtained when reading a code printed on a flat part other than a semiconductor wafer. can get.

〔Effect of the invention〕

As explained above, the present invention ranks the brightness of the binarized code in order of lightness, calculates the difference for each from the ranked numerical values, and binarizes at the point where this difference shows the maximum value. Therefore, even if there is a small difference in brightness between areas with and without a code, the threshold value can be accurately determined, and the presence or absence of a code can be determined accurately and in a short time.

[Brief explanation of the drawing]

FIG. 1 is a block system diagram showing an embodiment of a binary code reading device according to the present invention, FIG. 2 is an overall configuration diagram showing the overall configuration for reading a binary code, and FIG.
A code recognition flowchart to explain the operation of the device shown in the figure, Fig. 4 is an explanatory diagram showing blocks made up of codes, and Fig. 5 is an explanatory diagram showing a number line with digitized numerical values of the brightness of the code. , FIG. 6 is a block system diagram showing a conventional binary code reading device, FIG. 7 is a code recognition flowchart for explaining the operation of the device shown in FIG. 6,
FIG. 8 is an explanatory diagram showing a brightness histogram of a block composed of codes with a large difference in brightness, and FIG. 9 is an explanatory diagram showing a brightness histogram of a block composed of codes with a small difference in brightness. 1... Photoelectric conversion device, 2... A/D converter, 3...
・Block positioning section, 6... Code positioning section, 7
... code brightness detection unit, 8... recognition code determination unit,
9... Threshold determination unit.

Claims (1)

[Claims] An illumination device that illuminates a binary code surface printed on a semiconductor device from an oblique direction; and a photoelectric conversion device that captures an image of the binary code of the semiconductor device illuminated by the illumination device and outputs an electrical signal. an A/D converter that converts brightness into a numerical value from an electrical signal obtained by the photoelectric conversion device;
A block positioning unit that determines the position of a block composed of a binary code in which there is at least one code corresponding to white and one code corresponding to black from the signal output from the A/D converter; A code positioning unit that determines the position of the binary code from the code, a code brightness detection unit that converts the brightness of the determined position of the binary code into a digitized value, and a code brightness detection unit that ranks the brightness of the binary code in order of brightness. 1. A binarized code reading device comprising: a threshold determining unit which obtains each difference from the ranked numerical values and binarizes the difference at a point where the difference shows a maximum value.