JPS6132714B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device for reading information displayed on marks attached to the surface of an object, and the first object of the present invention is to read information displayed on marks attached to the surface of an object. The object of the present invention is to provide a method that allows reading without changing the reading direction even if the reading direction is changed.

An object of the second invention of the present application is to display the position of a pattern to be read on the surface of an object without error even if there is another pattern that is partially similar to the pattern that displays the position of the pattern. The purpose is to provide a method by which patterns can be detected.

<General Description of the Invention> The device of the present invention reads marks printed or pasted on the surface of an object such as a cardboard box. This mark has the shape shown in Figure 1 as an example, and has n decimal digits (n: any integer; in this example, 1
As an example, the number n=9) is displayed.
Note that the coordinate axes x, y and the inclination θ of the mark are defined as shown in FIG. 2.

FIG. 3 shows an example of the overall configuration of a reading device according to the present invention. Here, the mark 11 is attached to the object 16, and the object 16 moves on the conveyor 12. The recognition device 14 starts operating in response to a signal from the product arrival detector 13, and uses a camera 2 using a vidicon or the like.
(The case using a vidicon camera will be described below) processes the image of the mark 11, and reads and outputs the displayed n-digit decimal number. Note that the image rotation device 1 rotates the image during imaging and corrects the inclination θ of the mark. Further, the flash illumination device 15 is used to obtain a still image by eliminating blur caused by afterimages of the camera when an object moves at high speed. Therefore, if the object is to temporarily stop in front of the camera, the flash illumination device 15 is not necessary.

FIG. 4 is a basic configuration diagram of a mark reading device according to the present invention. The basic parts of this device are a right edge detection circuit 4, a top and bottom edge detection circuit 5, and a shape recognition circuit 8.
"The part that recognizes the external shape" of mark 11 consisting of
This is a part that recognizes a "character type code" pattern, which consists of a character pattern detection circuit 6, a character position detection circuit 7, and each digit character determination circuit 9.

Here, the former method correctly extracts marks written on objects mixed with letters and figures, and recognizes their positions and inclinations. The latter effectively utilizes the recognition results of the former to recognize the information meant by the mark 11.

By adopting such a configuration, the present invention can realize a mark reading device with a high correct reading rate on a small scale. For example, in order to correct pattern rotation (mark inclination), which is difficult to process by hardware, the inclination is first determined in the former and optical rotation correction is performed, so that the latter rotation scale is considerably small. For the same reason, a high correct reading rate can be maintained even if the mark position accuracy is poor.

In addition, while the former recognizes the mark's outer shape, information about the presence or absence of the mark and its position is given to the latter in the middle of the recognition process, so the "Character Type Code"
It is possible to read only the pattern accurately,
A high recognition rate can be obtained.

Furthermore, in the former case, even if processing is started on a pattern other than the mark by mistake, if a circuit system described later is adopted that can detect this and return the device to its initial state, it will become unreadable. The probability can be greatly reduced.

Hereinafter, the present invention will be explained in detail with reference to Examples.

<Example> In FIGS. 3 and 4, the image of the vicinity of the mark 11 on the object 16 captured by the vidicon camera 2 through the image rotation device 1 is digitized by the binarization circuit 200 and the sampling circuit 201. After that, it enters the two-dimensional local memory 3. This two-dimensional local memory 3 is a circuit that cuts out a local two-dimensional pattern (hereinafter referred to as a partial pattern) from an image. The cutting position of the partial pattern moves over the entire image as the vidicon camera 2 scans.

The right edge detection circuit 4 processes the partial pattern cut out by the two-dimensional local memory 3, and detects a certain angle (approximately 120 degrees as shown in FIG. 1) from the video image.
A pattern with an opening angle of , that is, a pattern at the right end of the mark is extracted. The upper and lower edge detection circuit 5 similarly processes the partial pattern, extracts a pattern in which the black and white boundary line is straight, that is, a pattern at the upper and lower edges of the mark, and further detects the y-direction of the mark based on the extracted upper and lower edge positions of the mark. Find the center.

By similarly processing the partial pattern, the character pattern detection circuit 6 extracts a "character type code" pattern indicating the numbers "0" to "9", and
The character position detection circuit 7 extracts the center in the x direction of each digit of the "character type code" pattern displayed with n digits.

In this way, four types of characteristic patterns representing the characteristics of each part of the mark are individually extracted. In addition, by using the two-dimensional local memory 3 and performing high-speed processing using dedicated hardware for each circuit, each feature pattern can be displayed anywhere on the image.
All are extracted during scanning of one field by the vidicon camera 2.

By the way, since characters and figures other than the mark 11 are printed on the surface of the object 16, the patterns extracted by the four types of detection circuits mentioned above include:
It includes things that are truly extracted from the mark and things that are not. The external shape recognition circuit 8 and each digit character determination circuit 9 are circuits for recognizing marks by separating marks other than these marks based on their coordinate relationships, selecting only marks that meet mark shape conditions. .

That is, the outer shape recognition circuit 8 is a circuit that recognizes the outer shape of a mark based on the right edge pattern of the mark extracted by the right edge detection circuit 4 and the upper and lower edge patterns of the mark extracted by the upper and lower edge detection circuit 5, and determines the mark position. and the inclination θ of the mark are output. Further, the center coordinates of the mark in the y direction determined by the upper and lower end detection circuit 5 are updated and stored every horizontal scan of the vidicon camera 2. (However, the y direction here is the direction shown in Figure 2, and as described later, it is taken to match the vertical scanning direction of the vidicon camera 2.) The center of this mark in the y direction is the "character" It coincides with the center of the "type code" pattern in the y direction, and is used by the character position detection circuit 7 and each digit character determination circuit 9 to determine the position on the video to be processed.

Furthermore, each digit character determination circuit 9 determines a "character type code" pattern based on the x-direction center of the "character type code" pattern obtained by the character position detection circuit 7 and the y-direction center obtained by the outer shape recognition circuit 8. The character type code of each digit is determined by detecting the position where the character pattern detection circuit 6 exists, and selecting only the output corresponding to this position from the output of the character pattern detection circuit 6.

The comprehensive judgment circuit 10 determines whether the mark external shape completely satisfies the mark conditions as a result of the extraction and judgment performed by each circuit in this way, or whether it is a "character type code".
determines whether n digits have been completely read and outputs the reading result.

In addition, this device performs imaging at least twice to read one mark, and in the first imaging, the amount of inclination θ of the mark determined by the external shape recognition circuit 8 is sent to the image rotation device 1, and the inclination is corrected. Afterwards, the image is taken again and the "character type code" pattern is determined.

Furthermore, when recognizing a mark on a moving object, it is necessary to read the mark when it is completely within the field of view of the camera. This judgment is made based on the mark position determined by the external shape recognition circuit 8. Images are taken periodically until the mark is at a predetermined position, and only the external shape of the mark is recognized repeatedly. It makes a judgment and outputs the reading results. Control of these imaging and processing sequences is carried out by the comprehensive judgment circuit 1.
Do this based on 0.

Note that the right edge detection circuit 4, the upper and lower edge detection circuits 5, the character pattern detection circuit 6, and the character position detection circuit 7
Two circuits perform real-time processing while the vidicon camera is scanning the effective field of view, but the external shape recognition circuit 8 and each digit character determination circuit 9 mainly perform processing during the horizontal retrace period.
The comprehensive judgment circuit 10 is configured to operate mainly during the vertical retrace period. Therefore, 1 field (16.7ms) of the vidicon camera
All processing is completed during this time, allowing high-speed reading.

Next, the specific configuration method and operation of each circuit will be explained.

<Image rotation device 1> As shown in FIG.
01 is rotated by a pulse motor 102 via gears 103 and 104. The Aurastone prism is a prism having a square optical axis cross section and a trapezoidal side surface, and an image passing through this prism rotates about the optical axis 105 by twice the prism rotation angle. Furthermore, the image becomes a mirror-symmetrical image with the left and right sides reversed.

This device controls the rotation angle of the image by the number of pulses applied to the pulse motor 102. As will be described later, the recognition device 14 shown in FIG.
The step angle and gear ratio of the pulse motor should be selected so that the pulse motor rotates by the same amount.

<Visicon Camera 2> This is an externally synchronized industrial ITV camera. The external synchronization signal required for this is the fourth
It is synchronized with the signal controlling the two-dimensional local memory 3 shown in the figure. The video signal of the business camera 2 is
It is processed as a two-dimensionally discretized digital image. In this case, the vertical scanning direction has already been discretized by the scanning lines of the vidicon camera, but the horizontal scanning direction is discretized by sampling at a cycle of 6 MHz. As a result,
The field of view of the vidicon camera is as shown in Figure 6 below.
It is divided into 240 squares in the vertical scanning direction and 320 squares in the horizontal scanning direction (these squares are called picture elements [pe]).

FIG. 6 shows the relationship between the field of view of the vidicon camera and the mark 11 in this device. In this case, the mark is imaged through the Aurastone prism and becomes a mirror-symmetric image, and the coordinate axes x, y shown in Figure 2 are
The image appears as shown in Figure 6. Note that in each of the following figures, all marks indicate the state in which the images were taken in this manner.

The horizontal scanning direction of the camera is the mark horizontal direction (x
The image is taken perpendicular to the direction). By doing this, the vidicon camera 2 scans in the direction in which the "character type code" pattern is arranged.
In the dimensional local memory, the "character type code" pattern can be sequentially extracted digit by digit. Therefore, the character pattern detection circuit 6 only needs to repeat the same process for the "character type code" pattern of n digits.

<Two-dimensional local memory 3> This circuit is described in "Shape position recognition device" by the present inventors
112236)], the details will be omitted.

With this circuit, the shape of any part of the input video,
A plurality of partial patterns indicating the arrangement can be sequentially cut out over the entire image in synchronization with the scanning of the vidicon camera 2. Moreover, the coordinates of the cutout position can be known at the same time.

<Right edge detection circuit 4> This circuit detects the pattern at the right edge of the mark ( (pattern with a constant opening angle) can be extracted regardless of its inclination θ. Here, the right edge detection circuit 4 outputs a "right edge detection" signal indicating that the right edge of the mark has been extracted, and its coordinates "mark right edge x coordinate" and "mark right edge y coordinate".

<Upper and Lower End Detection Circuit 5> The partial patterns processed by this circuit are two congruent adjacent rectangles E and F shown in FIG.
The positions of these partial patterns cut out in the two-dimensional local memory 3 move in the horizontal direction from a to b to c as shown in the figure as the vidicon camera 2 scans horizontally. Of course, next, along with vertical scanning, it also moves in the vertical direction (downward in the figure).
At position b in the figure, that is, when the boundary between partial patterns E and F overlaps the bottom edge of the mark (corresponding to the left edge in the figure), E is a pattern that is entirely "black" and F is a pattern that is entirely "white". becomes. Conversely, at position c, which correctly overlaps the upper end of the mark (the right end in the figure), E becomes a pattern that is entirely "white" and F becomes a pattern that is entirely "black". Therefore, by determining these conditions, the upper and lower ends of the mark can be extracted.

However, since noise is present in real video patterns, it is not always possible to have a pattern that is entirely "black" or "white". Furthermore, even if the mark is tilted, the pattern will not be entirely "black" or "white" as shown in FIG. Therefore, the following determination is made.

The number of "white" picture elements in partial pattern E is e, the number of "white" picture elements in F is f, and Condition 1 e>T ₁ Condition 2 f>T ₁ Condition 3 T ₂ <e+f<T ₃ . It is assumed that when conditions 1 and 3 are satisfied simultaneously, upper end extraction is performed, and when conditions 2 and 3 are satisfied simultaneously, lower end extraction is performed.

Condition 1 and Condition 2 are the conditions for determining the top and bottom edges, respectively.The conditions for the entire surface being "black" and the entire surface being "white" are relaxed, and T ₁ is selected to be approximately 20% smaller than the area of one rectangle. This makes it possible to eliminate the effects of noise and mark inclination (up to about θ=20°). Further, condition 3 is a condition for accurately extracting the positions of the upper end and the lower end. That is, as can be seen from FIG. 8, this method utilizes the fact that when the value of e+f accurately captures the top or bottom edge of the mark, it exactly matches the area of one rectangle. This condition also takes noise into account,
T ₂ and T ₃ are each 0.9 times the rectangular area,
It should be about 1.1 times.

In this way, the upper and lower ends of the mark can be extracted, but there are many partial patterns in the video that are similar to these patterns, and these are also extracted in the same way. Therefore, this circuit next determines whether the upper and lower ends have been extracted at appropriate intervals to confirm that the upper and lower ends of the mark have truly been extracted. Furthermore, at this time, the center coordinates of the mark in the y direction are calculated from the cutout position coordinates given from the two-dimensional local memory.

Based on this principle, the circuit configuration is as shown in FIG. 9. That is, the numbers e and f of "white" picture elements in the partial patterns E and F cut out in the two-dimensional local memory 3 are counted by adders 51 and 51', and e+f is counted by adder 51''. Ru.
This result is added to the comparators 52, 52', 52'', and the above conditions 1 to 3 are judged.Finally, the result is passed through the AND circuits 53, 53', and the "upper end" and "lower end" of the mark are extracted. “1” when is performed
, otherwise outputs "0". These outputs are sequentially applied to shift registers 54 and 54', respectively, and shifted each time the image scan advances by one picture element.

The shift register 54' includes OR circuits 55, 5.
5' and 55'' are connected, and the OR circuit output and the output of the shift register 54 are connected to the AND circuit 5.
6, 56', and 56''. These circuits are used to determine whether the top and bottom edges have been extracted at reasonable intervals, allowing some variation. The spacing between the bottom edges is 30pe
Since the camera field of view is set so that
Normally, as shown in Figure 6, the bottom edge is extracted first, and then the top edge is detected when the vidicon camera has advanced 30 pe of scanning. Therefore, when the lower end is extracted and the "1" output from the AND circuit 53' is shifted to the 32nd bit of the shift register 54 and reaches the AND circuit 56', the upper end is extracted and output from the AND circuit 53. "1" has been shifted to the second bit of shift register 54', and this signal "1" also reaches AND circuit 56' via OR circuit 55'. As a result, the two inputs of the AND circuit 56' become "1" and the output becomes "1", and the "upper and lower end detection" signal "1" is outputted via the OR circuit 57.

Also, when the distance between the top and bottom edges of the mark is 29pe,
When the "1" of the lower end extraction reaches the 32nd bit of the shift register 54, the "1" of the upper end extraction reaches the 3rd bit of the shift register 54'. The output becomes "1" one after another, and the output of the OR circuit 57 becomes "1".
becomes. In the same way, the distance between the top and bottom edges of the marks is
It determines that it is between 27pe and 32pe and outputs a "upper and lower end detection" signal.

On the other hand, the partial pattern cutout position coordinate (y direction) given from the two-dimensional local memory 3 is subtracted by ΔY ₁ in the subtraction circuit 58, and is latched as the "center y coordinate" when the "upper and lower end detection" signal is output. It is temporarily stored in the circuit 59. Note that ΔY ₁ is
The center coordinate of the true mark in the y direction and the two-dimensional local memory 3 when the “upper and lower end detection” signals are output.
It is the difference from the partial pattern cutting position coordinates pointed to, and the coordinate difference between the center of the mark and the bottom edge of the mark is 15pe.
and 2pe which is delayed for receiving a shift in the shift register 54', resulting in 17pe.

Note that in this circuit, the amount by which the signal "1" for top edge extraction and bottom edge extraction is shifted in the shift registers 54, 54' before determining the spacing between the top and bottom edges of the mark changes depending on the size of the spacing between the top and bottom edges. Therefore, the y-coordinate of the mark center can always be determined correctly without changing ΔY ₁ .

<Character Pattern Detection Circuit 6> By utilizing the "Shape Position Recognition Device" (Japanese Patent Application No. 7499/1983) developed by the present inventors, it is possible to extract a "character type code" pattern.
That is, the character pattern detection circuit 6 detects "0" to
Extract the “character type code” pattern of “9” and perform the corresponding “character pattern i detection” (i=
0, 1, 2...9) signals are sent to each digit character determination circuit 9.

<Character position detection circuit 7> As shown in FIG. 10, the partial pattern processed by this circuit is based on the y-direction length ( 20pe). The position of this partial pattern G cut out in the two-dimensional local memory 3 moves from a to b to c as the vidicon camera scans in the vertical direction. Regarding the position in the horizontal direction, processing is performed only at the center of the mark based on the mark center coordinates determined by the outer shape recognition circuit 8.

When the position of c, that is, the partial pattern G is on the "character type code" pattern, at least half of G is a "white" pattern. on the other hand,
At the position b on the mark and outside the "character type code" pattern, the partial pattern G becomes a "black" pattern on the entire surface. Furthermore, the field of view of the vidicon camera is set so that the width in the x direction of the "character type code" pattern of the mark is 10 pe, and the width between the "character type code" patterns is 5 pe. Therefore, if threshold processing is performed to make the entire area "white" when a certain area or more is "white", the partial pattern G
If the change in is observed in the vertical scanning direction, it will be as shown in Fig. 11. By determining this condition, the location of the "character type code" pattern in the x direction can be known.

The configuration of this circuit is shown in FIG. Like the upper and lower end detection circuit 5 described above, this circuit is also designed to cope with noise and pattern size fluctuations. The adder 71 counts the number of "white" picture elements in the partial pattern G, and the following comparator 72 determines whether the partial pattern G is "white" or "black". This threshold T ₄
If it is set to about 80% of the area (20) of the partial pattern G, the influence of noise can be removed. Also, the comparator 72 outputs "1" when it is "white", and outputs "1" when it is "black".
Outputs “0” when . This output is sent to the shift register 73 only when the partial pattern G is correctly centered in the y direction of the mark. Therefore, the comparator 78 sends a shift signal to the shift register 73 only when the cutout position coordinates given from the two-dimensional local memory 3 match the "character pattern center y-coordinate" _Yc given from the outline recognition circuit 8. Try to add it. In this way, the shift register 73 is set to 1 of the vidicon camera 2.
It is shifted once for each horizontal scan, and changes in the partial pattern G between "white" and "black" are sequentially recorded on the shift register 73.

The five AND circuits 74 are connected to the shift register 73
From the “white” and “black” information of the partial pattern G stored in
Extract the pattern. (In Fig. 12, the AND circuit 74 is an abbreviation for an inverter circuit.The interval between these change points should be 10pe as shown in Fig. 11, but there is some variation. When the allowable value is 8 to 11pe, it is determined that the center of the "character type code" pattern in the x direction has been detected.For this purpose, two OR circuits 75, 2
AND circuits 76 and OR circuits 77 are used. These circuits operate in the same manner as the upper and lower end detection circuits 55 to 57 shown in FIG. 9 described above, and the OR circuit 77 outputs a "character position detection" signal "1".

As explained above, the "character position detection" signal output from this circuit is a timing signal indicating that the scanning of the image has progressed to the center of the "character type code" pattern of each digit in the x direction.

<Outer shape recognition circuit 8> This circuit recognizes the mark outer shape from the right edge pattern of the mark extracted by the right edge detection circuit 4 and the upper and lower edge patterns of the mark extracted by the top and bottom edge detection circuit 5. y coordinate,""mark right end y coordinate,""mark right end x coordinate,""markinclination," etc., and output them.

First, the principle of external shape recognition will be explained. As can be seen from the field of view of the vidicon camera 2 shown in FIG. 6, as the scanning of the image progresses, the right end of the mark is extracted first, and then the upper and lower ends of the mark are extracted. Then, extraction of the upper and lower ends of the mark continues until scanning of the image reaches the left end of the mark. Therefore, when the right edge pattern is extracted, the upper and lower edge patterns are extracted immediately after that, or the upper and lower edge patterns are extracted continuously for the length of the mark (equivalent to 160 horizontal scans). The outline of the mark can be recognized by determining whether the mark is visible or not. These judgments are
This is done every horizontal scan. Incidentally, erroneous recognition can be prevented by also determining whether the y-coordinates of each of the extracted patterns are continuous without sudden changes.

FIG. 13 is an explanatory diagram of an external shape recognition method based on the above-mentioned principle, and FIG. 14 is a flowchart thereof. Note that the hatched portion in FIG. 13 represents the processing area. At the time when video scanning is started, the processing area is expanded to the full extent in the horizontal scanning direction (y direction). Next, when the right end of the mark is extracted, the processing area is limited to the range of the "right end y-coordinate" of the mark ±ΔY. Then, if the upper and lower ends of the mark are subsequently extracted within this processing area, the processing area is updated to the mark "center y coordinate" ±ΔY. Below, 1
Similar processing is performed for each horizontal scan.

If the extraction of the upper and lower edges is interrupted, if it is less than the predetermined N times, the process continues, and when it reaches N times, it returns to the processing area at the start of scanning and extracts the right edge. Start over.
By doing this, even if the right edge detection circuit 4 causes incorrect extraction due to printing of something other than the mark,
It is possible to return to correct mark recognition. As for the parameters, if ΔY=3N=5 or so, misrecognition due to noise or printing other than marks can be prevented.

Furthermore, if the positional fluctuation of the mark 11 imaged by the vidicon camera 2 is known in advance and is within a range smaller than the camera field of view, the processing area at the time of starting imaging is not filled in the horizontal scanning direction, and the mark 11 is It is set to cover the existence range of 11. In addition, if ΔY is changed at the time of extracting the right edge and the time of extracting the top and bottom edges, the inclination of the mark θ
It is also possible to make a stricter judgment even when the value of .

In parallel with the above-described processing, this circuit determines the mark length and measures the mark inclination θ. That is, after right end extraction, the length is determined based on whether upper and lower end extraction continues for 100× horizontal scanning (interruptions of less than N are allowed). In addition, after extracting the right edge, 100× from the difference between the center y coordinate of the horizontal scanning eye and the right edge y coordinate.
Find tanθ.

The specific configuration of this circuit is shown in FIG. Here, the flip-flop 81 stores whether or not the right end has already been extracted, and is set by the "right end detection" signal from the right end detection circuit 4 in FIG. 4 to indicate that the extraction of the upper and lower ends has been interrupted N times. It is set by the output of the counter 803 that counts the .
Incidentally, this flip-flop 81 is naturally set at the time when scanning of the image is started.

The aforementioned processing area settings are made using the data selector 8.
2 to window comparator 86. The latch 83 is for temporarily storing the "right end y coordinate" output from the right end detection circuit 4 or the "center y coordinate" output from the upper and lower end detection circuit 5. Which one to remember is flip-flop 8.
It is determined by switching the data selector 82 according to the output of 1, and if the right end has already been extracted, the "center y coordinate" is latched, otherwise the "right end y coordinate" is latched. However, storage is performed only when the upper and lower ends or the right end, respectively, are extracted within the processing area.

Adder 84 and subtracter 84'
Add or subtract ΔY to the coordinates to find the upper and lower limit coordinates of the processing area. This coordinate is applied to window comparator 86 via data selector 85. When the y-coordinate of the pattern extracted by the right edge detection circuit 4 or the upper and lower edge detection circuits 5 is within the processing area, the window comparator 86 applies a trigger signal to the latch 83 and stores this y-coordinate.

Note that the data selector 85 is a flip-flop 8.
Switching is performed by the output of 1, and the processing area that fills the entire horizontal scanning direction (Y _U −
After the right end of Y _L ) is extracted, the processing areas determined by an adder 84 and a subtracter 84' are provided to a window comparator 86, respectively. With such a configuration, the recognition method described above can be realized.

The latches 87, 87', and 87'' are for storing and outputting the "y-coordinate of the right edge of the mark," the "x-coordinate of the right edge of the mark," and the "y-coordinate of the center after 100 horizontal scans from detection of the right edge," respectively. 87,8
7' may use the "right edge detection" signal as the trigger signal. Furthermore, the latch 87'' is triggered when the count value of the counter 88, which counts the number of horizontal scanning lines after the right edge is detected, reaches 100. It memorizes that the length of is sufficient and outputs a "mark length OK" signal.

An inverter 801, an AND circuit 802, and a counter 803 count the number of times upper and lower end detection is interrupted,
This is to reset the flip-flop 81 that stores the right edge detection when the number N times has been reached, and return the operation of the outline recognition circuit to its initial state.

<Each digit character determination circuit 9> This circuit determines the center coordinates of the "character type code" pattern obtained by the character position detection circuit 7 and the outer shape recognition circuit 8, and the "character type code" extracted by the character pattern detection circuit 6. This is a circuit that compares the "code" pattern with the "code" pattern, determines and stores them for each digit.

FIG. 16 shows the configuration of this circuit. Comparator 91
sets the output to "1" when the "character pattern center y-coordinate" output from the external shape recognition circuit 8 and the "cutout position y-coordinate" given from the two-dimensional local memory 3 match. This output indicates the timing in the y direction at which the partial pattern to be input to the character pattern detection circuit 6 is correctly cut out on the center coordinates of the "character type code" pattern.

When this output and the timing signal indicating the center of the "character type code" pattern in the x direction, that is, the "character position detection" signal which is the output of the character position detection circuit 7, both become "1", the AND circuit 92 Gate circuit 94 is opened. By this, "character pattern 0 detection" which is the output of the character pattern detection circuit
Ten types of signals are sent to the converter 95. Here, the converter 95 detects the added “character pattern i” (i=0, 1, 2
This is a decimal-to-binary conversion circuit that converts i into a binary number depending on which one of 9) is "1".

The above processing is performed for each "character type code" pattern of each digit as the image is scanned, and is repeated nine times in the case of this embodiment. As each digit is processed, the output of the converter 95 is stored in the buffer memory 96, and finally the "read character" is stored.
Output as a signal.

Note that the counter 93 counts the number of digits of the processed "character type code" pattern, and uses this as the "number of characters".
This is for outputting as .

<Comprehensive Judgment Circuit 10> This circuit makes a comprehensive judgment on the results extracted and judged by each of the above circuits, and outputs the reading result. It also controls the processing sequence of each circuit.

This device targets an object 1 with a mark 11 attached to it.
Marks can be recognized even when the camera 6 is moving or once stopped in front of the camera. Since the former case can be easily inferred from the latter case, only the latter case will be explained.

FIG. 17 is a flowchart showing the processing of this circuit. This circuit checks whether each circuit has processed the entire mark length, whether the mark position is in a readable position, and whether the "character type code" that has been read is checked.
It is determined whether n digits are present. If there is an abnormality in these, it is output as an "abnormal" signal, and if everything is normal, a "reading character" is output along with a "reading complete" signal. Imaging is repeated until the mark position on the image reaches a recognizable position, and when the mark inclination is measured, the "mark inclination" is sent to the image rotation device along with the "image rotation" signal, which is a timing signal for image rotation. . Next, the image is taken again, the image with the mark tilt corrected is processed, and the "character type code" is read. Note that when the above imaging has been repeated M times, an "abnormal" signal is output to return the device to its initial state and prepare for the arrival of the next product.
Here, M is determined depending on usage conditions, but is approximately 3.

FIG. 18 is a configuration diagram of this circuit. The operation of this circuit will be explained below.

Flip-flop 111 is a product arrival detector 13
It is set by the "Product Arrival" signal which is the output of the "Product Arrival" signal, and is reset when the reading is completed, and is used to determine the operating state of the device. A flip-flop 116 is used to store whether or not image rotation has been performed.

The comparator 112 outputs "1" when the "mark right end x coordinate" which is the output of the right end detection circuit 4 is between the set ranges _x1 and _x2 . As explained above, this is to determine whether the mark position on the video is a readable position.

The AND circuit 113 determines that the output of the comparator 112 and the "mark length OK" signal output from the outer shape recognition circuit 8 are both "1".
This result is output via AND circuits 114 and 115 as an "image rotation" signal. AND circuit 1
14 is to output the "image rotation" signal only when the "vertical synchronization" signal is "1", that is, when the imaging of one field is completed.

Similarly, the purpose of the AND circuit 115 is to detect only when the output of the flip-flop 111 is "1", which means that the product has arrived but the reading has not yet been completed, and that image rotation has already been performed. This means that the "image rotation" signal is output only when the output of the flip-flop 116 is not "1". In this way, the image rotation can be performed only once when recognition of the mark outline is completed normally.

Note that the AND circuits 121, 118, 125, 1
28, 122, 123, 119, 126 etc.
It performs the same function as the AND circuits 114 and 115 described above. Therefore, the explanation will be omitted below.

The comparator 117 is for confirming that the "number of characters" output from each digit character determination circuit 9 is equal to the number n of "character type code" patterns in the mark. This output and the output of the AND circuit 113 that determined the mark position described above are connected to the flip-flop 1.
16 and a "vertical sync" signal, and is applied to an AND circuit 118, and is outputted via an AND circuit 119 as a "read end" signal. By doing so, all the circuits can operate normally according to the sequence and output the "reading complete" signal only when reading of the mark is completed.

A portion consisting of an inverter 120 and an AND circuit 121 outputs "1" when processing is not performed over the entire mark length, and outputs this as an "abnormal B" signal via AND circuits 122 and 123. Inverter 127 and AND circuit 128
The part consisting of outputs "1" when the mark is not in a recognizable position. This output and the output of the AND circuit 121 are applied to a counter 132 via a portion consisting of an OR circuit 129, an inverter 130, and an AND circuit 131. By doing so, it is possible to count the number of times that images are taken repeatedly because processing was not performed over the entire mark length or because the mark was not located at a recognizable position. When this count reaches M, the counter 132 outputs an "abnormality A" signal.

In addition, the inverter 124 and the AND circuit 125,
The portion consisting of 126 detects that the "number of characters" read has not reached n and outputs an "abnormal C" signal. In this way, the “abnormal” signal is
By classifying and outputting data into B and C, even if reading is not performed normally, it is possible to estimate the cause.

The portion consisting of the OR circuit 133 is a circuit for resetting the flip-flop 111 and returning the device to its initial state when the reading of the mark is completed or when the number of repetitions of imaging reaches M times.

The above description has been made regarding one embodiment. The configuration of the present invention is extremely flexible. For example, as in the mark pattern shown in Fig. 19, the outline of the mark can be arbitrarily changed depending on its purpose (such as the extent to which there are patterns that are confusing to the mark), and the black and white may also be reversed. . In order to read the mark pattern shown in FIG. 19, in the circuit described above, the right edge detection circuit 4 is removed and the upper and lower edge detection circuit
A part of the outline recognition circuit may be changed so that the mark shape is determined by continuously extracting the "lower edge pattern". Furthermore, the correspondence between the "white" and "black" patterns and the "1" and "0" signals may be reversed.

Further, some so-called pattern matching techniques can be immediately applied to each of the "detection circuits" 4 to 7. Alternative means in this case can be easily found by those skilled in the art, so their explanation will be omitted here.

The present invention is also highly flexible regarding the components used. For example, any imaging device can be used instead of the vidicon camera 2. It is also possible to perform electrical scanning in the y direction using a one-dimensional photodiode array, and to perform an operation equivalent to scanning in the x direction by moving the conveyor 12. The rotation of the image can also be done by mechanically rotating the camera, or electrically by changing the "focus potential" of the vidicon camera 2.

Note that the mark is not limited to the one using the "character type code" shown in FIG. 1; any similar pattern can be easily read by modifying a part of the circuit system. In addition to patterns representing numbers, it is also possible to add patterns representing other characters.

According to the first invention of the present application, since the signal is cut out in the direction intersecting the symbol string and the mark is allowed to shift, even if the symbol string is tilted, the signal can be followed while allowing the tilt. Can read patterns.

According to the second invention of the present application, the position of the mark is found from the positional relationship between the plurality of parts of the mark and the partial pattern for which a match has been detected, so even if there are many partially similar patterns, it is possible to find the position of the mark with certainty. can be read.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram showing one row of marks, Fig. 2 is an explanatory diagram showing an inclined state of the marks, Fig. 3 is an explanatory diagram showing an application state of the present invention, and Fig. 4 is an explanatory diagram showing the circuit configuration of the entire device. 5 is an explanatory diagram showing an example of the configuration of the image rotation device, FIG. 6 is an explanatory diagram showing the relationship between the field of view of the vidicon camera and the mark, and FIGS. An explanatory diagram showing the detection state, FIG. 9 is a block diagram also showing a configuration example,
10 and 11 are explanatory diagrams of the detection state by the character position detection circuit, FIG. 12 is a block diagram showing an example of the circuit configuration, FIG. 13 is an explanatory diagram showing the operation of the external shape recognition circuit, and FIG. 14 is the same. flowchart,
FIG. 15 is a block diagram showing an example of the circuit configuration, FIG. 16 is a block diagram showing an example of the configuration of each digit character determination circuit, FIG. 17 is a flowchart showing the operation of the overall determination circuit, and FIG. 18 is the same. FIG. 19 is a block diagram showing an example of the circuit configuration, and is an explanatory diagram showing a modified example of the character pattern used in the present invention. 1: Image rotation device, 2: Camera, 3: Two-dimensional local memory, 4: Right edge (pattern) detection circuit, 5: Upper and lower edge detection circuit, 6: Character pattern detection circuit, 7:
Character position detection circuit, 8: Outline recognition circuit, 9: Character determination circuit for each digit, 11: Mark, 14: Recognition device.

Claims (1)

[Claims] 1. A pattern row consisting of a plurality of first patterns extending in a first direction, and a pattern row located at a predetermined distance from the pattern row, with a boundary line extending in the first direction. A target object marked with an extended second pattern is sequentially scanned in a second direction intersecting the first direction, and a two-dimensional partial pattern is obtained from the signals obtained by the scanning. are sequentially cut out, and it is detected whether or not the cut out partial pattern is a partial pattern that includes a part of the boundary line of the second pattern, and if the detection result is positive, the second pattern of the first pattern separated by the predetermined distance from the boundary line;
Detecting a first position in the direction of , and detecting a second position of the first pattern in a direction perpendicular to the second direction using the cut out partial pattern at the first position. Then, based on the detected first and second positions, a region where the first pattern exists is extracted, and the region is extracted for each scanning line that intersects with the second position. A mark reading method characterized by reading a pattern of No. 1. 2 A pattern row consisting of a plurality of first patterns extending in a first direction, and a second pattern row located a predetermined distance away from the pattern row and whose boundary line extends in the first direction. sequentially scanning an object marked with a pattern in a second direction intersecting the first direction, sequentially cutting out two-dimensional partial patterns from the signals obtained by the scanning, and It is detected whether or not the generated partial pattern matches a partial pattern including a part of the boundary line of the second pattern, and if the detection result is positive, the detected partial pattern is a position in the second direction of the first pattern that is the predetermined distance away from the boundary line; and a position of the first pattern that is the predetermined distance away from the boundary line where a match was later detected.
It is determined whether the difference between the position of the pattern in the second direction and the position of the pattern in the second direction belongs to a predetermined range, and if the determination result is positive, the second direction of the first pattern detected after the detecting a second position of the first pattern in a direction perpendicular to the second direction using a partial pattern at a first position in the direction; A mark reading method comprising reading a first pattern by extracting an area where the first pattern exists.