JP2778870B2 - Barcode decoder - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bar code decoder used in a bar code reader for reading a bar code from a bar code label printed or affixed to a product or the like.

[0002]

2. Description of the Related Art In recent years, in the retail industry and the like, a bar code label printed or affixed to a product and indicating the identification code of the product is scanned with a laser beam or the like, and the reflected light is read to read the bar code. The data is stored in ECR (ElectricCash Register) or PO
Bar code readers for transmitting to S (Point of Sales) terminals are widely used.

[0003] Bar codes used in such applications include EAN (European Article Number) and JAN.
(Japanese Article Number) UPC (Univ
ersal Product Code) is known.
For example, FIG. 3A shows a typical bar code. FIG. 3A shows an EAN / bar composed of a left margin, a left guard bar, a left data character (6 characters), a center bar, a right data character (6 characters), a right guard bar, and a right margin. J
FIG. 3B shows an EAN / J bar code consisting of a left margin, a left guard bar, a left data character (4 characters), a center bar, a right data character (4 characters), a right guard bar, and a right margin.
FIG. 3C shows the EAN / J bar code.
FIG. 3D shows a UPC-E bar code having a left margin, a left guard bar, a data character (six characters), a right guard bar, and a right margin. It is. EAN /
JAN-13, EAN / JAN-8, and UPC-A bar codes are double segment codes having half segments on the left and right across the center bar, and UPC-E bar codes are single segment codes without the center bar. .

Further, EAN / JAN-13, EAN / JA
The right guard bar of the bar code of N-8 and UPC-A is shown in FIG.
As shown in FIG. 4 (a), the right guard bar of the UPC-E bar code is composed of one space of one module width and two bars, as shown in FIG. 4 (c). Consists of three spaces and three bars, and EAN / JAN-13, EAN / JAN-8, UPC
As shown in FIG. 4B, the center bar of the bar code -A is composed of three spaces of one module width and two bars.

Further, each data character has a parity. For example, all the right characters of EAN / JAN-13 have even parity, and EAN / JAN-13 has a parity.
And the UPC-E character have a combination of parity as shown in the table below.

[0006]

[Table 1]

A bar code reader for reading such a bar code has a configuration shown in FIG. That is, a barcode symbol is optically scanned, the reflected light is received, converted into an electric signal, and then a binarized barcode signal is input to the decoding unit 1 to detect a margin, a guide bar, a center bar, and perform character detection. Decoding, the number of characters, parity check, and when it is determined that a correct bar code has been read, the decoding unit 1
Is supplied to the CPU 2 so that the CPU 2 stores the barcode in the RAM 3. If the bar code is a double segment code, the left and right half segments are assembled, a modulo 10 check is performed, and the bar code is transmitted to the host computer 4 as an upper-level device via an interface. In the case of a code, the bar code is transmitted to the host computer 4 via the interface after performing a modulo 10 check.

[0008] The configuration of the data code section 1 used in such a bar code reader is conventionally the configuration shown in FIG. That is, the bar code signal is input to the bar width counter 5, and the bar width counter 5 counts the space and bar width to quantize. The count value from the bar width counter 5 is supplied to an incoming margin detecting unit 6, an outgoing center bar detecting unit 7, an incoming center bar detecting unit 8, an outgoing margin detecting unit 9, and a character decoding unit 10, respectively.

When the valid margin and guard bar are detected prior to the character, the incoming margin detecting section 6 outputs a high level incoming margin detecting signal IMG, and the outgoing margin detecting section 9 outputs the valid guard bar and valid bar following the character. When a margin is detected, a high level output margin detection signal OMG is output. Also, the outgoing center bar detecting unit 7
When a valid center bar is detected following the character, a high-level outgoing center bar detection signal OCB is output. When a valid center bar is detected prior to the character, the incoming center bar detecting section 8 outputs a high-level incoming center bar detecting signal ICB. Is output.

The input margin detection signal IMG from the input margin detector 6 is input to one input terminal of a two-input AND gate 12 after a predetermined timing delay in a delay circuit 11, and the output center bar detector 7 is input to the other input terminal of the AND gate 12. In addition, the input center bar detector 8
The input center bar detection signal ICB is supplied from the two-input AND gate 1 after a predetermined timing delay in the delay circuit 13.
The output margin detection signal OMG from the output margin detector 9 is input to one input terminal of the
4 is input to the other input terminal. Output FOR from AND gate 12 and output from AND gate 14
BCK is supplied to the decoding control unit 15.

The character decoding section 10 starts decoding a character when an incoming margin and a guard bar or an incoming center bar are detected, and performs decoding until an outgoing center bar or an outgoing margin and a guard bar are detected. The output from the character decoding unit 10 includes data characters and parity information of the characters, and is stored in the data memory 16 one character at a time. The number of data characters output from the character decoding unit 10 is counted by the character number counter 17.

The decode control unit 15 determines that the output FOR from the AND gate 12 is at a high level, that is, when an input margin, a guard bar and an output center bar are detected, and that the output BCK from the AND gate 14 is at a high level, that is, when the input center bar is at a high level. When the output margin and guard bar are detected, the character data is read from the data memory 16 and the count value of the character number counter 17 is read, the number of characters and parity of the data are checked, and whether the decoding result is valid or not is checked. And the barcode type is determined. When the barcode data is valid, an interrupt is issued to the CPU 2 and the decoded data is transferred to the CPU 2 together with its type.

The bar code reading direction is determined by the signal FOR.
When the signal BCK is at a high level, the direction is a forward direction from the center bar to the margin, and when the signal BCK is at a high level, the direction is a reverse direction. The information on the reading direction is also used to determine the code type from the combination of the parities.

In order to read the half segment of the double segment code in the decoding section having such a configuration, the margin, guard bar, data character, and center bar must be confirmed as valid.

For example, when scanning the label of EAN / JAN-13 as shown in FIG. 7A, the input margin, guard bar, and output center bar are confirmed, the number of data characters is 6, and the data Parity is EAN / J
If the signal is valid as AN-13, the decoding unit outputs EAN /
This data is recognized as the left half segment data of JAN-13.

In order to read the single segment code, it is sufficient that the left margin, the left guard bar, the data character × 6 and the center bar are at least valid. This is because the right guard bar of the single segment code has a form in which one module bar is added to the center bar of the double segment code ((b) of FIG. 4) as shown in FIG. 4 (c). Can be identified as the center bar, it can be identified as the left half segment of the double segment code from the difference in parity combination.

For example, U which is a single segment code
When the PC-E label is scanned as shown in FIG. 7B, the left margin, the left guard bar, the data character × 6, and the center bar are confirmed, and the parity of the data is valid as UPC-E. If there is, the decoding unit is UPC
Recognize this data as -E.

As described above, in order to simplify the structure of the decoding unit, the right guard bar of the single segment code is detected by a circuit common to the center bar of the double segment code, and the right margin is not detected. Was. That is, the discrimination between the half segment of the double segment code and the single segment code is performed only by the difference in the combination of the parity.

[0019]

The decoding section 1
May be deformed due to the influence of electrical or optical noise, label printing quality, or the like. As a result, the width of some of the bars or spaces is different from the original width, and the character may be misread and the parity may change from even to odd or from odd to even. When such a state occurs, the majority of the data is invalidated because the combination of the parity does not hold as a barcode, the modulo 10 check does not match, the left and right segment data do not match, and so on. Is not misread.

However, for example, when the width of two bars or spaces in the left half segment of EAN / JAN-13 is simultaneously deformed, the combination of parity is established as UPC-E. Was misread as a single segment code. Since the single segment code does not have the right character, no data check is performed when assembling the left and right data. If the modulo 10 check is satisfied, the data is regarded as correct data and transferred to the host computer. Would be.

Accordingly, an object of the present invention is to provide a bar code decoder having a simple structure and capable of greatly reducing misreading of recognizing a double segment code as a single segment code.

[0022]

According to the present invention, a bar code symbol of a bar code having a margin, a guard bar and a center bar is optically scanned, the reflected light is received, converted into an electric signal, and then binarized. A bar code decoder for detecting a margin, a guard bar and a center bar from a bar code signal and decoding bar code data has a center bar, a symmetrical margin, a center bar detection output and a right margin of a bar code having a guard bar configuration,
The right guard bar detection output detects the left and right margins without the center bar, the right margin of the bar code where the guard bar is not symmetrical, and the guard bar detection means, and the right margin and guard bar are detected by this detection means, and the character data is valid. And a determination means for invalidating the character data when the right margin and the guard bar are not detected.

[0023]

In the present invention having such a configuration, even if the combination of the parity has no center bar and the left and right margins and the guard bar are formed as asymmetric single segment codes, the right guard bar and the right margin are not detected. Character data is determined to be invalid.

[0024]

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

As shown in FIG. 1, a bar code symbol is optically scanned, its reflected light is received, converted into an electric signal, and then converted into a binary code.
The bar width counter 21 counts the width of the space and the bar and quantizes them. The count value from the bar width counter 21 is input to the input margin detection unit 2.
2, outgoing center bar detecting section 23, incoming center bar detecting section 2
4. Outgoing margin detecting section 25 and character decoding section 2
6 respectively.

The above-mentioned incoming margin detecting section 22, outgoing center bar detecting section 23, incoming center bar detecting section 24, outgoing margin detecting section 25 and character decoding section 26 are composed of the above-mentioned incoming margin detecting section 6, outgoing center bar detecting section 7 and FIG. The input center bar detector 8, the output margin detector 9, and the character decoder 10 perform exactly the same functions.

The input margin detection signal IMG from the input margin detection unit 22 is input to one input terminal of a two-input AND gate 28 after a delay of 6 characters in a delay circuit 27, and is output to the output center bar detection unit. The outgoing center bar detection signal OCB from 23 is input to the other input terminal of the AND gate 28. The input center bar detection signal ICB from the input center bar detection unit 24 is input to one input terminal of a two-input AND gate 30 after a delay of 6 characters is performed by a delay circuit 29, and is output from the output margin detection unit 25. The output margin detection signal OMG is input to the other input terminal of the AND gate 30.

The input margin detection signal IMG from the input margin detection section 22 is also delayed by the delay circuit 27 and further delayed by three clocks by the delay circuit 31 to be applied to one input terminal of the two-input AND gate 32. The output margin detection signal OMG from the output margin detection section 25 is input to one input terminal of a two-input AND gate 33.

The output from the AND gate 28 is delayed by three clocks in a delay circuit 34, and then supplied as a signal FOR to a decode control unit 35 and to the other input terminal of the AND gate 33. The output from the AND gate 33 is supplied to the decode controller 35 as a signal EFOR.

The output from the AND gate 30 is a signal BC
K is supplied to the decode control unit 35 and to the other input terminal of the AND gate 32. The output from the AND gate 32 is supplied to the signal EBCK.
Is supplied to the decode control unit 35.

The output from the character decoding unit 26 includes data characters and parity information of the characters, and is stored in the data memory 36 one character at a time. The number of data characters output from the character decoding unit 26 is counted by a character number counter 37.

The decode control unit 35 includes a delay circuit 34
When the signal FOR from the AND gate 30 is at a high level, that is, when the input margin, guard bar and output center bar are detected, and when the signal BCK from the AND gate 30 is at a high level, that is, when the input center bar, output margin and guard bar are detected, the data memory 36 is output. , And the count value of the character number counter 37, and
The number of characters and parity of the data are checked to determine whether the decoding result is valid and to determine the barcode type.

The decoding control unit 35 determines whether the signal EFOR from the AND gate 33 is at a high level, that is, when an incoming margin, a guard bar and an outgoing center bar, an outgoing guard bar and a margin are detected, and the signal EBCK from the AND gate 32 is output. When a high level, that is, an incoming center bar and an outgoing margin, a guard bar, and further an incoming margin and a guard bar are detected, the character data is read from the data memory 36 and the count value of the character number counter 37 is read. The bar code type is checked to determine whether the decoded result is valid as a UPC-E code and to determine the bar code type.

When the bar code data is valid, the decode control unit 35 interrupts the CPU 38 and transfers the decoded data to the CPU 38 together with its type.

In the embodiment having such a configuration, the EA
A bar code signal obtained by reading a bar code symbol of N / JAN-13 from the left side is inputted,
Detects the left margin and left guard bar, the center bar is detected by the outgoing center bar detecting unit 23, the number of data characters decoded by the character decoding unit 26 is 6, and the parity of the data is valid as EAN / JAN-13. If so, the decoder control unit 35 sets the EAN / JA
It is recognized as the left half segment data of N-13. Also, the center bar is detected by the incoming center bar detecting unit 24, the right margin and right guard bar are detected by the outgoing margin detecting unit 25, and the number of data characters decoded by the character decoding unit 26 is 6, and the parity of the data is If the data is valid as EAN / JAN-13, the decoder control unit 35 recognizes the data as right half segment data of EAN / JAN-13.

In the case of a UPC-E bar code symbol, for example, a bar code signal read from the left side is input, the left margin and the left guard bar are detected by the input margin detecting section 22, and the center bar is detected by the output center bar detecting section 23. If the number of data characters decoded by the character decoding unit 26 is 6 and the parity of the data is valid as UPC-E, but the signal EFOR from the AND gate 33 is not at a high level, the decoder The control unit 35 does not recognize the barcode data as UPC-E and invalidates it. That is, if the output guard bar and the output margin are not detected, the barcode data is invalid as UPC-E barcode data.

For example, when reading from the right side, the center bar is detected by the incoming center bar detecting section 24, and the left guard bar and the left margin are detected by the outgoing margin detecting section 25. Even if the number of data characters decoded at 26 is 6 and the parity of the data is valid as UPC-E,
If the signal EBCK from the AND gate 32 is not at a high level, the decoder control unit 35 does not recognize it as UPC-E barcode data and invalidates it. That is, if the incoming margin and the incoming guard bar are not detected, the barcode data is invalid as UPC-E barcode data.

As described above, the right guard bar of the single segment code is detected by the same circuit as the center bar of the double segment code, and the delay circuits 31 and 3 are added to the conventional circuit.
4 and AND gates 32 and 33 are simply added, so that the configuration is simple.

Further, even if the center bar, guard bar, and margin are detected, and the number of data characters is correct and the parity of the data is valid as UPC-E,
If the signals from the AND gates 32 and 33 are not at a high level, the bar code data of the UPC-E is invalid, so that the recognition of the bar code data of the UPC-E can be made more reliable and the erroneous reading can be greatly reduced. Can be reduced. That is, even if the width of the two bars or spaces of the left half segment data of the EAN / JAN-13 is simultaneously deformed and the combination of the parity is established as the UPC-E, the EAN / JAN-13 cannot be used. Since the outgoing guard bar and the outgoing margin are not detected from the left half segment data, the barcode data is invalidated.

The UPC code includes a half segment consisting of six characters and a half segment consisting of four characters. The number of bars and spaces between the incoming margin and the outgoing center bar and between the incoming center bar and the outgoing margin vary depending on the number of characters. Therefore, the configuration of the delay circuits 27 and 29 is replaced with a circuit including two delay circuits 41 and 42 and one OR gate 43 as shown in FIG. That is, the detection signal from the detection units 22 and 24 is delayed by four characters by the delay circuit 41, further delayed by two characters by the delay circuit 42, and the detection signal delayed by four characters. The detection signal delayed by six characters is output via the OR gate 43.

In this way, regardless of whether the number of characters is four or six, the timing of the incoming margin detection signal IMG and the output center bar detection signal OCB can be matched, and the input center bar detection signal ICB can be output at the same time. The timing can be matched with the margin detection signal OMG. Therefore, decoding can be performed whether the half segment is composed of six characters or four characters.

In the above-described embodiment, each component has a hardware configuration. However, the present invention is not limited to this. The configuration can also be configured by software using a program.

[0043]

As described above in detail, according to the present invention, the right guard bar and the right margin of a single segment code are detected by using the same detection means as the double segment code to simplify the structure. The present invention can provide a bar code decoder which can greatly reduce erroneous reading of recognizing a double segment code as a single segment code.

[Brief description of the drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention.

FIG. 2 is a circuit diagram of a delay unit according to another embodiment of the present invention.

FIG. 3 is a diagram showing a barcode configuration of a UPC-E system.

FIG. 4 is an enlarged view showing a configuration of a guard bar and a center bar of a UPC-E system bar code.

FIG. 5 is a block diagram illustrating a configuration of a barcode reading device.

FIG. 6 is a block diagram showing a conventional example.

FIG. 7 is a view for explaining the relationship between bar code reading and decoding processing of EAN / JAN-13 and UPC-E.

[Explanation of symbols]

22 ... in margin detection unit, 23 ... out center bar detection unit
24 ... in center bar detection unit, 25 ... out margin detection unit
26: Character decoding unit, 27, 29, 31, 34
... delay circuits, 28, 30, 32, 33 ... AND gates
35 ... Decoding control unit.

Claims (1)

(57) [Claims] 1. A bar code symbol of a bar code having a margin, a guard bar, and a center bar is optically scanned, the reflected light is received, converted into an electric signal, and then converted to an electric signal. A bar code decoder that detects a center bar and decodes bar code data has a center bar, has a symmetrical margin, a center bar detection output of a bar code having a guard bar configuration, a right margin, and a right guard bar detection output. Means for detecting the right and left margins, the right margin of the bar code in which the guard bar is not symmetrical, and the guard bar. When the right margin and the guard bar are detected by this detecting means, the character data is validated, and the right margin and the guard bar are detected. When there is no character A bar code decoder, further comprising a determination unit for invalidating data.