JPH0323952B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a reading device suitable for reading characters printed on the surface of an object.

[Background of the invention]

Conventionally, in order to inspect model numbers and the like stamped on incoming items in logistics systems, workers have to visually check the numbers, which has the drawback of workers misreading the numbers. In addition, it has been practically impossible to introduce character reading devices such as OCR, which directly read characters, into this field because reading errors can occur in poor working environments and the cost is high.

[Purpose of the invention]

An object of the present invention is to accurately read characters even in poor working environments.

[Summary of the invention]

In the present invention, three circular marks are attached to the surface of an object, and characters are recognized by reading these with a camera. The mutual spacing between the three circular marks is determined for each character.

Therefore, we calculated the coordinates of the three circular marks on the surface of the object input from the camera, and calculated the area, perimeter, and length of the three sides of the triangle formed by the positions of the three circular marks. Characters are recognized by comparing the characteristics and selecting the character with the closest characteristics.

Since the object to be read is a circular mark, it is resistant to noise and can be easily recognized. Furthermore, since one character is expressed by the mutual positional relationship of the three circular marks, the character can be sufficiently expressed with the three circular marks.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIGS. 1 to 4.

The surface of the goods flowing within the distribution system is marked with a string of combinations of letters A to Z and numbers 0 to 9, which can be directly determined by visual inspection by an inspector. 3 on the surface of the article so as to be inside the specific area 14 below each letter A to Z, 0 to 9.
circular marks 15 are marked.

Each arrangement of the three circular marks 15 corresponds to each letter A to Z,
They are arranged differently for each of 0 to 9 as shown in Figures 1a and 1b.

In FIG. 3, the article is marked with the character string "F523" shown in FIG. String "F523"
Below the mark, a circular mark 15 is marked on the surface of the article 1 for each letter "F", "5", "2", and "3". For later explanation, an X coordinate axis and a Y coordinate axis are set as shown in FIG. Assume that the article 1 is illuminated by a lamp 3 as shown in FIG.
If a recognition start command is now input to the MPU 7 from the I/O port 13, the MPU 7 outputs the recognition start command to the camera 2. As a result, the camera 2 starts inputting images and outputs a composite video signal, which is a composite of the synchronization signal and the analog image signal, to the amplifier circuit 4 and the synchronization signal separation circuit 9. The amplifier circuit 4 extracts an analog image signal from the composite video signal, amplifies it, and outputs it to the AD converter 5. A synchronization signal separation circuit 9 separates a vertical synchronization signal and a horizontal synchronization signal from the composite video signal, and outputs them to an address generation circuit 10, a memory write timing generation circuit 11, and an image input determination circuit 12. When the image input determination circuit 12 receives the first vertical synchronization signal, it outputs a signal requesting the right to use the bus to the MPU 7, and when it receives the second vertical synchronization signal, it stops outputting this signal. , for MPU7,
It is notified that the image data has been written into the image memory 6. When the memory write timing generation circuit 11 receives the bus use permission signal from the MPU 7, it generates a horizontal synchronization signal from the synchronization signal separation circuit 9.
The timing for writing the output of the AD converter 5 into the image memory 6 is created using the synchronization signal of the MPU 7 and the counter in the memory write timing creation circuit 11. Further, the address generation circuit 10 receives the horizontal synchronization signal from the synchronization signal separation circuit 9, the synchronization signal of the MPU 7, and the address generation circuit 1.
The address in the image memory 6 where the data from the AD converter 5 should be stored is created using the counter in 0. The MPU 7 performs character recognition using the image data in the image memory 6 based on a program flow consisting of steps a to j shown in FIG. The memory 8 stores the program shown in FIG. 4 and is used as a work area for the MPU 7.
The MPU 7 outputs the recognized results to the outside via the I/O port 13.

The character code recognition procedure is shown based on the flow of FIG. The feature of this recognition algorithm is that the character code is composed of three circular marks 15,
The center coordinates of each circle are determined from each coordinate of Y, and data regarding the area, circumference, and length of three sides of the triangle formed by the center coordinates of each circular mark 15 is obtained from the data of the coordinates in advance. By comparing these values of the desired character code, the unique desired character code characterized by that feature is recognized.

According to this embodiment, since characters can be recognized using features based on three-point coordinates, the recognition algorithm becomes simple and the device becomes inexpensive. Further, even if a failure occurs in the device, the line of the distribution system will not be stopped because the characters written together with the mark 15 can be directly viewed and read.

〔Effect of the invention〕

As described above, according to the present invention, since characters are recognized by the three circular marks, the present invention is resistant to noise and can prevent misreading even under adverse working environments. Furthermore, since characters can be expressed by changing the positions of the three circular marks, a large number of characters can be expressed.

[Brief explanation of drawings]

1a and 1b are characters to be recognized by the apparatus according to the present invention and the arrangement of marks corresponding to the characters; FIG. 2 is a block diagram of the structure of the apparatus according to the present invention; and FIG. 3 is a recognition apparatus according to the present invention. FIG. 4 is a program flowchart showing a character recognition procedure in the apparatus shown in FIG. 2. 1...Articles marked with letters and marks,
2...Camera, 3...Lamp, 4...Amplification circuit,
5...AD converter, 6...image memory, 7...
...MPU, 8...Memory, 9...Synchronization signal separation circuit, 10...Address creation circuit, 11...Memory write timing creation circuit, 12...Image input determination circuit, 13...I/O port, 15... ...Circular mark.

Claims (1)

[Claims] 1 Find the coordinates of three circular marks on the surface of the object input from the camera, and calculate the area, perimeter, and length of three sides of the triangle formed by the positions of the three circular marks, and the characteristics of the intersection that was created in advance. A method for reading characters that is characterized by comparing the characters with the characters and selecting the character with the closest characteristics.