JPH0437466B2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field Subject to the Invention] This invention relates to a method for reading the mesh code of each field type code in a code matrix in which a plurality of field type codes each representing several bits of information are arranged in one code. .

[Prior art and its problems]

Conventionally, codes are printed on the packaging of products and are used for various management purposes. This code generally uses a so-called barcode that expresses the code by the thickness and arrangement of black and white lines, but this barcode has the following problems. In other words, since barcodes arrange information in one dimension, they can only express a small amount of information, and barcode printing requires high precision, making it impossible for humans to directly draw the code. Moreover, the barcode cannot be easily read by humans.

In order to solve this problem, it is constructed by combining four rectangular meshes in a square shape.
In addition, a so-called Tagata code was devised in which a code is displayed by selectively coloring each mesh in black or white. This makes it possible to arrange the codes two-dimensionally and express more information. Therefore, you can draw only the frame of the field and selectively fill in each mesh like a mark sheet. It is now possible to write a code, and since the code is basically 4 bits, it can be easily read by humans.

However, there is almost no innovation in how to read these codes, how to arrange the codes, or with auxiliary graphics.

[Purpose of the invention]

This invention takes into consideration these conventional drawbacks,
The purpose is to accurately know the position of the Tagata code and to read the data accurately.

[Summary of the invention]

In order to achieve the object, the present invention forms a code matrix using a plurality of tag-shaped cords, and a hook-shaped reference having a predetermined dimension is formed outside the four corners of the code matrix and maintains a predetermined distance from the code matrix. A line is provided, and the center coordinates of the taga code are calculated from the relative positional relationship between the reference line and the code matrix, and the code of each mesh is read from the center.This makes it possible to read the code manually. Furthermore, even if the image of the Tagata code is shifted in the rotation direction, the position of each mesh can be read accurately.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings.

In other words, in Fig. 2, reference numeral 1 indicates the basic configuration of the well-known Tagata cord. For example, four square meshes each having a side of 2 mm are combined in a square shape to form a Tagata cord having a side of 4 mm as a whole. be done. This field code can represent information of a predetermined number of bits by filling out each mesh.
For example, if four meshes are used, there will be 4 bits of information, and the number will be 16. As shown in Figure 3, if all the meshes are filled in, the value becomes 0, and if none of the meshes are filled in, it becomes 15, and if the upper left mesh is left and the other meshes are filled in, then the value becomes 15. 1. If you leave the bottom left and fill in the other meshes, you can get 2. If you leave the top right and fill in the other meshes, you can get 4. If you fill out the upper half, you can get 8.

In Figure 1, a code matrix 2 is formed by arranging a plurality of Tagata codes 1 at predetermined intervals in a matrix of M rows and N columns. In this embodiment, 20 Tagata codes are arranged vertically and horizontally. It is formed by arranging them in a matrix of 4 rows and 5 columns with an interval of 2 mm between each. Then, around the code matrix 2, a hook-shaped reference line 3 having a predetermined dimension is placed outside the four corners of the code matrix 2, maintaining a predetermined distance from the code matrix. In the case of the one shown in Fig. 1, these reference lines are placed 2 mm apart in the vertical and horizontal directions from the taga codes 1 and 1 located at the four corners of the code matrix 2, and the width, that is, the thickness of the line, is set to 2 mm. and the vertical and horizontal dimensions from each corner are set to 6 mm. Therefore, the corners C ₁ and C ₄ of the reference lines 3 and 3
Alternatively, the vertical length connecting C ₂ and C ₃ is 6 (M+1), and the horizontal length connecting the corners C ₁ and C ₂ or C ₄ and C ₃ is 6 (N+1).

Next, a method for reading tag format codes according to the present invention will be explained with reference to FIGS. 4 to 6.

First, from the reference line 3 placed outside the four corners of the code matrix 2, the four corners C ₁ , C ₂ ,
Find the coordinates of C ₃ and C ₄ . Next, the center coordinates of the field codes 1, 1 are determined based on the positional relationship between the coordinates of these four corners and the field codes 1, 1. From there, the center coordinates of the four meshes of the Tagata codes 1 and 1 are found, and the square area centered around the coordinates, that is, the value of each mesh, is read and the code is decoded.

Figure 4 shows 1 determined by the hook-shaped reference line 3.
There are also four corners _{C 1 ,} C ₂ ,
C ₃ and C ₄ are shown. x and y in the figure are reference lines 3
It is displayed in a tilted direction. This is because generally the x and y directions of the captured image are not necessarily parallel to the reference line.

The captured image is then scanned in the x and y directions to determine the reference line 3, that is, each side of the hook-shaped figure, and then the four corners C ₁ , C ₂ , C ₃ , C ₄
Find the coordinates of.

It is difficult to obtain a stable image at the corners of the reference line 3 in the captured image, and if the four corners are directly determined by scanning, the error will be large. Therefore, the outer periphery of the hook-shaped figure is determined, and then the coordinates of the four corners are calculated.

Assume now that the image magnification of the camera section of the reading device is constant. First, consider obtaining one edge. It is assumed that the angle of the hook-shaped figure in the image falls within an angle range of ±45 degrees. FIG. 5 shows a hook-shaped figure that fits within the image. In this figure, while scanning in the x direction, a line where a certain number of black pixels can be detected in a row is searched for. The number is assumed to be 80% of the number of pixels corresponding to the thickness of the hook-shaped line in the image. The coordinates of the first black pixel of this first detection line,
The coordinates of the first black pixel when scanning this line in reverse, that is, the points A ₁ and B ₁ in FIG. 4 are memorized.
Next, scan a scan line separated by y ₁ in the y direction,
Memorize the coordinates of points A ₂ and B ₂ . One last time y
Scan a scan line separated by y ₁ in the direction, point A ₃
and memorize the coordinates of B ₃ . This _y1 is the maximum interval between three scanning lines that can detect the outer side when the hook-shaped figure is tilted by 45 degrees. and the obtained point A ₁
For ~A ₃ and B ₁ ~ _{B 3} , a series of points with constant intervals in the x direction is adopted. For example, the slope of a hook-shaped figure is 0.
When the angle is between 45 degrees and 45 degrees, points A ₁ to _{A 3} are adopted (5th
Figure A). Also, if the slope is between 0 degrees and -45 degrees, the point is
B ₁ to _{B 3} are adopted (Figure 5 b).

When the obtained point sequence is A ₁ to A ₃ , scanning is performed as shown in FIG. 5A. Then, the points A ₁ and B ₁ obtained by the first scan are memorized. Next, the scanning start point and scanning direction are rotated 90 degrees clockwise and scanning is started. In this scan, for the first time, a line in which black pixel columns continue for the previously determined number of columns is determined. And the black pixel that appears when scanning from the left on this line
Find the coordinates of A ₄ and the coordinates of the first black pixel B ₄ when scanning in reverse. In the same way, find the coordinates of points A ₅ , B ₅ , A ₆ , and B ₆ in Fig. 5A. Then, the eight points found were A ₁ , B ₁ , A ₄ , B ₄ , A ₅ ,
Find the equation of the straight line connecting the four points from B ₅ , A ₆ , and B ₆ ,
The coordinates of the four corners are determined as these intersection points.
When the obtained point sequence is B ₁ to B ₃ , scanning is performed as shown in Figure 5 B, and the obtained point sequence is A _{1 to B 3} .
~ Find the coordinates of the four corners in the same way as in ₃ .

That is, C ₁ = (x ₁ , y ₁ ), C ₂ = (x ₂ , y ₂ ), C ₃ = (x ₃ , y ₃ ), C ₄ = (x ₄ , y ₄ )...(1).

Next, the coordinates of the center of each field code are determined from the coordinates of the four corners. Here, the straight line C ₁ C ₂ can be considered as a straight line that passes through the center of the row when one more row is added to the upper end of the code matrix 2. Similarly, straight lines C ₂ C ₃ , C ₃ C ₄ and
C ₄ C ₁ also has Tagata code 1 outside the code matrix,
When considering the row or column of 1, it can be thought of as a straight line passing through the center of the Tagata code of this extra row or column. Therefore, by dividing the length of the line segment C ₁ C ₂ by N+1, the row direction and pitch x _p of the field code 1, 1 can be determined. Similarly, by dividing the length of the line segment C ₁ C ₄ by M+1, the pitch y _p of the field codes 1 and 1 in the column direction can be found. In actual measurement, x _p is a line segment to reduce errors.
C ₁ C ₂ and C ₃ C ₄ , y _p uses line segments C ₂ C ₃ and C ₁ C ₄ .

The rotation angle θ of the entire code with respect to the screen can also be determined from C ₁ and C ₂ .

When C ₁ is the origin, C ₁ C ₂ is the x axis, and C ₁ C ₄ is the y axis, the center coordinates of the Tagata code closest to C ₁ are
Let it be P ₁₁ . The interval between the Tagata cords is equal to half of one side of the Tagata cords in both the x and y directions. Therefore, in FIG. 6, the center coordinates P _ij of the Tagata code in the i-th row and the j-th column are expressed by the following equation.

Px=x _pi , Py=y _pj ...(4) Figure 5 shows the relationship between the center of the Tagata code and the center of each mesh. Center coordinates of each mesh Q ₁ , Q ₂ ,
Q ₃ and Q ₄ are expressed as follows.

The coordinates in the actual image are each point C ₁ , C ₂ , C ₃ , C ₄
It forms an angle of θ with the coordinate system whose axis is the direction of the sides of the rectangle connecting the , so it is as follows.

1 centered on the center of each mesh thus determined
Pixels within a square area with side length a are read, and the value within that area is determined to be 0 or 1. After determining the values for the four meshes, the Tagata code 1
decode the value of Do this for all Tagata codes. For example, if the mesh values of Q ₁ , Q ₂ , Q ₃ , and Q ₄ are 1, 0, 1, and 0, respectively (black is 0 and white is 1), the value of this taga code is It becomes 5.

When reading the Tagata code using the above algorithm, it can be read even when the Tagata code is tilted, and even codes written by humans can be read as long as the center of the mesh is properly marked.

A block diagram of a reading device for realizing the above algorithm is shown in FIG. 4 is a sheet on which a matrix of tagata codes 1, 1 is written, 5 is a light source, 6 is a lens, and 7 is a two-dimensional image sensor. The tag code 1 written on the sheet 4 by the light source 5;
Illuminate 1. An image of the illuminated tagata codes 1, 1 is formed onto a two-dimensional image sensor 7 by a lens 6. The two-dimensional imaging element is a clock generator 11.
Analog data of each pixel is output by a drive signal generated from a clock generated by a drive circuit 10. The output analog data is amplified through a preamplifier 8 and sent to a binarization circuit 9. The binarization circuit compares the sent analog signal with a predetermined reference voltage and converts it into binary data. At this time, the DMA controller 12 receives the clock generated from the clock generator and generates and provides an address to the frame memory 13. The binarized data sent at this time is stored in the frame memory. The control circuit 14 receives a signal from the trigger circuit 17,
An image data input signal is provided to the DMA controller 12. Therefore, the image data when the trigger is applied is binarized and stored in the frame memory 13. After the image has been input, the control circuit 14
executes the above-mentioned Tagata code reading algorithm, displays the result on the display 16, and outputs a signal to external equipment through the output circuit 15.

FIG. 7 shows an example of the appearance and usage of the reading device. Reference numeral 19 denotes a reading section of the reading device, which illuminates the sheet 4 with light from the light source 5 and captures an image. Image input is performed by pressing the trigger switch 20. When the decoding of the Tagata codes 1, 1 is completed, the results are displayed on the display 16. The results are also sent to external equipment through the output terminal 18.

〔Effect of the invention〕

As described above, the present invention provides a hook-shaped reference line having a predetermined dimension and maintaining a predetermined distance around a code matrix made up of a plurality of T-shaped code, and the relative relationship between this reference line and the code matrix. The center coordinates of each field code are calculated from the positional relationship, and the code of each mesh is read from the center, so it is possible to read not only codes printed by machines but also codes drawn by humans. In addition, even if the image is tilted during reading, the position of each mesh of each tag type code can be calculated and found, making it easy to decode, and the operation of the reading device is easy. There is a certain effect.

[Brief explanation of drawings]

Fig. 1 shows an example of the method for reading the Tagata code according to the present invention, and shows the arrangement of its patterns, Fig. 2 shows the basic configuration of the Tagata code, and Fig. 3 shows an example of the display of the Tagata code. Configuration diagram shown, No. 4
Figures 5 and 6 are explanatory diagrams of the reading method;
FIG. 7 is an external perspective view of the reading device, and FIG. 8 is a block diagram of the reading device. 1...Tagata code, 2...Code matrix,
3...Reference line, 4...Sheet, 5...Light source, 6...
... Lens, 7 ... Two-dimensional image sensor, 8 ... Preamplifier, 10 ... Drive circuit, 11 ... Clock generator, 12 ... DMA controller, 13 ...
...Frame memory, 14...Control circuit, 15...
Output circuit, 16... Display, 17... Trigger circuit, 18... Output end, 19... Reading unit.

Claims (1)

[Claims] 1 A plurality of T-shape codes, which are constructed by combining four square meshes in a T-shape and display the code by the shade of the color of each mesh, are arranged in a matrix at predetermined intervals. A code matrix is formed by forming a code matrix, and a hook-shaped reference line having a predetermined dimension is provided at a predetermined distance from the code matrix on the outside of the four corners of the code matrix, and the reference line and the above-mentioned code matrix are connected. A method for reading a tag code, characterized in that the center coordinates of each tag code are calculated from the relative positional relationship, and the code of each mesh is read from the center.