JP2731610B2 - Barcode decoder and barcode decoding method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a barcode decoder and a barcode decoding method.

[Prior Art] A bar code reader is configured as shown in FIG. That is, the light beam from the light source 1 is applied to a polarizer 2 such as a polygon mirror or a vibrating mirror to be polarized and scan on the barcode label 3. After the reflected light from the barcode label 3 is detected by the photodetector 4, the analog circuit 5 performs processes such as photoelectric conversion, signal amplification, and A / D conversion, and has a time width corresponding to each bar width of the barcode. It is supplied to the decoder 6 as a bar code digital signal.

For example, when a barcode as shown in FIG. 8A is scanned from left to right and read, the barcode digital signal input to the decoder 6 has width data d () corresponding to each bar or space. i), d (i + 1), d (i +
2), d (i + 3), d (i + 4), d (i + 5), ...
Becomes

The digital signal input to the decoder 6 is first stored in a memory. The decoder 6 performs the decoding process shown in FIG. 9, for example, using a CODE128 bar code as an example.

First, the value of the pointer i indicating the bar data number is set to 0. Subsequently, it is checked whether the width data d (i) is a margin.

If so, the decoding of the first character is started. First, a pattern code corresponding to the width of the black and white bar pair is obtained. That is, width data d (i + 1), d
(I + 2), d (i + 3), d (i + 4), d (i +
5) From d (i + 6), d (i + 1) + d (i +
2), d (i + 2) + d (i + 3), d (i + 3) + d
(I + 4), d (i + 4) + d (i + 5), d (i +
5) Each value of + d (i + 6) and total width data d (i + 1) +
d (i + 2) + d (i + 3) + d (i + 4) + d (i +
5) The value of + d (i + 6) is obtained, and the number of modules (the minimum unit of the bar width) of each pair width is obtained from each value. For example, in the case of (a) in FIG. 8, it is "2,1,1,4,1,2". Then, from this module number, 2 + 1, 1 + 1, 1 + 4, 4+
The calculation of 1 is performed to obtain a 4-digit pattern code "3255" corresponding to the width of the black and white bar pair.

The character value is obtained by referring to the decode table using the thus obtained pattern code as an address. The character values correspond to various character codes, start codes, stop codes, and the like, and can be converted into various character codes, start codes, stop codes, and the like by using the character values.

If the obtained character value is the start character, it is determined that the reading is in the forward direction, and the pointer i is set to +
6 In the case of a stop character, reading is performed in the reverse direction, so that the pointer i is incremented by +7.

In FIG. 8, when scanning from left to right, there is a start character following the margin, and the character value obtained by the pattern code "3255" is the character value of the start character.

If the obtained character values are not the start and stop character values, the margin detection is continued while the pointer i is incremented by one until the start and stop character values are obtained.

When the pointer i is set to +6 (or 7), decoding of the second character starts. In this decoding process, similarly to the previous process, a pattern code corresponding to the width of the black and white bar pair is obtained, and a character value is obtained from the decode table using the pattern code as an address.

Thereafter, this process is sequentially repeated to convert the character of each bar code into a character value. When the character values corresponding to the start character and the stop character are decoded again, it is determined that the decoding of the barcode has been completed, and the decoded data is output from the decoder 6 to the data processing device. In FIG. 8, when scanning is performed from left to right, the last is a stop character and its pattern code is "5642".

In this way, the read data of the barcode is decoded into a character value for each character with reference to the decode table in the decode 6 and output.

Conventionally, the character values corresponding to the start character and the stop character set in the decode table are each set to only one address. Therefore, only one pattern code determined corresponding to the start character and the stop character is used. The address was specified and the character value was determined.

[Problems to be Solved by the Invention] However, in the case where only one character value respectively corresponding to the start character and the stop character is set in the decode table, the digital signal of the start character and the stop character input to the decoder is If there is any change, decoding cannot be performed at all, and there is a problem that decoding of the entire bar code cannot be performed at all.

By the way, the bar code digital signal input to the decoder is generated by an analog circuit, but the end portion of the digital signal, that is, the signal portion corresponding to the start character or the stop character easily changes due to the characteristics of the analog circuit. Further, for example, when scanning a bar code label by performing polarization using a vibrating mirror, the change in scanning speed is large at the end of scanning, so that the end of the digital signal is also likely to change.

For this reason, in the conventional apparatus, the start character and the stop character cannot be decoded, and as a result, the entire bar code cannot be decoded at all.

Therefore, according to the present invention, even if the digital signal corresponding to the start character and the stop character slightly changes, the start character and the stop character can be decoded to the corresponding character value by the decode table, and thus the barcode reading efficiency can be improved. A bar code decoder and a bull bar code decoding method are provided.

[Means for Solving the Problems] According to a first aspect of the present invention, a bar code including at least two types of width values, a white bar and a black bar, is converted into a pattern corresponding to the width of each white bar and black bar. A bar code decoder that replaces each bar code with a code and decodes each bar code character into a character value by referring to the decode table using the pattern code as an address. Set the character values of the start character and the stop character at the address specified by the pattern code in which the character is replaced, and start character at the address specified by the pattern code in which a part of the start character and the stop character are transformed into a different pattern. The character values of the start character and the stop character correspond to the plurality of pattern codes or designated addresses.

According to a second aspect of the present invention, a bar code including a white bar and a black bar having at least two types of width values is provided.
When a bar code character is replaced with a pattern code corresponding to the width of each white bar and black bar and each bar code character is decoded to a character value by referring to the decode table using the pattern code as an address, a start adjacent to the margin is used as a decode table. While setting the character value of the start character and the stop character at the address specified by the pattern code that replaces the correct barcode pattern of the character and the stop character,
A start / stop character decode table in which the character values of the start character and the stop character are set at the address specified by the pattern code in which a part of the start character and the stop character are transformed into a different pattern; Provide a data character decode table that sets the character value of the data character at the address specified by the pattern code that replaces the bar code pattern of the intervening data character. When decoding the bar code character, the start character and the stop character are used. The start / stop character decode table is referenced to decode the character value, and the data character is read by referring to the data character decode table. It is to decode the Kuta value.

According to a third aspect of the present invention, a first start / stop character decode table and a last start / stop character decode table are provided as start / stop character decode tables, and the first start character or stop character in bar code reading is used. The start / stop character decoding table may be decoded to a character value, and the last start character or stop character may be decoded to a character value with reference to the last start / stop character decoding table.

According to a fourth aspect of the present invention, the last start / stop character decode table is separated into a start character decode table and a stop character decode table. Is referred to selectively.

[Operation] In the present invention having such a configuration, not only when the bar code patterns of the start character and the stop character are regular patterns, but also a slightly modified pattern, the decode table is addressed by the bar code pattern. Since the character values of the start character and the stop character are set at the positions shown in FIG.

When the character value of the start character is decoded by the first start / stop character decode table, the last character can be determined to be a stop character. Therefore, the stop character is decoded into a character value by the stop character decode table. When the character value of the stop character is decoded by the first start / stop character decode table, the last character can be determined to be the start character. Therefore, the start character is decoded into the character value by the start character decode table.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing the structure of a decoder. A bar code digital signal from an analog circuit obtained by reading a bar code with a photodetector is input to an edge interval counter 61 and an address counter 62, respectively.

The edge interval counter 61 counts the interval of each edge of the barcode digital signal by a reference clock,
The numerical value is written in a RAM (random access memory) 63.

A scanning signal output from a light beam scanning unit is further input to the address counter 62. When writing the numerical value from the edge interval counter 61 into the RAM 63, the address is specified by the address counter 62 in synchronization with the start of each scan.

64 is a CPU (central processing unit).
And a ROM (read only memory) 65 and an address bus 66 and a data bus 67.

The CPU 64 reads out the numerical data from the RAM 63 to obtain the module value of each black bar and white bar, and obtains the pattern code of each character from the module value. Each character is decoded to a corresponding character value with reference to a decode table provided in the ROM 65 using the pattern code of each character as an address.

As the decoding table, as shown in FIG.
Start / stop character decode table 651,
A stop character decode table 652, a start character decode table 653, a forward data character decode table 654, and a reverse data character decode table 655 are provided. The stop character decode table 652 and the start character decode table 653 constitute the last start / stop character decode table. The stop character decode table 652 is used when bar code reading scanning is performed in the forward direction. The start character decode table 653 is used when the bar code reading scan is performed in the reverse direction.

The start / stop character decode table
Taking the case of CODE128 as an example, the character value of a plurality of start characters A and the character values of a plurality of stop characters B are stored in an address specified by a 4-digit pattern code as shown in FIG. “106” is set.

That is, the start character A is not only the position addressed by the accurate pattern code “3255”, but also the pattern codes “2255”, “3155”, and “3245” partially modified.
The character value "103" is also set at the position addressed by "3254", "3256", "3265", "3355", and "4255". The stop character B is not only a position addressed by an accurate pattern code “3224”, but also a part of the pattern codes “2244”, “3124”, and “321” which are slightly modified.
The character value "106" is also set at the position addressed by "4", "3223", "3225", "3234", "3324", and "4224".

No character value is set in the blank part. The character value for the start character is "10
Start character B and character value of "4" are "105"
, But this is omitted in FIG.

The stop character decode table 652 has COD
Taking the case of E128 as an example, a plurality of character values “106” of the stop character B are set at the address specified by the 4-digit pattern code as shown in FIG.

That is, the stop character B is not only the position addressed by the correct pattern code “5642”, but also the pattern codes “4642”, “5542”, and “5632”, which are partially modified.
The character value “106” is also set at the position addressed by “5641”, “5643”, “5652”, “5742”, and “6642”.

The start character decode table 653 has COD
Taking the case of E128 as an example, as shown in FIG. 5, the character values of a plurality of start characters A "103" and the character values of a plurality of start characters B "104" are stored in an address specified by a 4-digit pattern code. And a character value “105” of a plurality of start characters C is set.

That is, the start character A is not only a position addressed by the accurate pattern code “3552”, but also a partly modified pattern code “2532” “3452” “3542”
The character value “103” is also set at the position addressed by “3551”, “3553”, “3562”, and “3652”.
The start character B has the correct pattern code "53
32 ", as well as some slightly modified pattern codes" 4332 "" 5232 "" 5322 "" 533 "
The character value “104” is also set at positions addressed by “1”, “5333”, “5342”, and “6332”. The start character C is the correct pattern code "5532"
The pattern addresses "5522", "5531", "5533" and "5542" are of course slightly modified
The character value “105” is also set at the position addressed by “5632” and “6532”.

The CPU 64 of the decoder performs the processing shown in FIG. 6 with reference to the numerical data stored in the RAM 63 and the respective decode tables stored in the ROM 65.

First, the value of the pointer i indicating the bar data number is set to 0. Subsequently, it is checked whether the width data d (i) is a margin.

If so, the decoding of the first character is started. First, a pattern code corresponding to the width of the black and white bar pair is obtained.

First, the start / stop character value is obtained by referring to the start / stop pattern table 651 using the thus obtained pattern code as an address. At the beginning of the barcode scan data, a start character (forward direction) or a stop character (reverse direction) is determined depending on the reading direction, and either character value is obtained. If neither the start nor the stop character value can be read, an error occurs.

When the start character value is obtained, the pointer i is set to +6, and when the stop character value is obtained, the pointer i is set to +7.

When the pointer i is set to +6 (or 7), decoding of the second character starts. In this decoding process, a pattern code corresponding to the width of the black-and-white bar pair is obtained in the same manner as the previous process. If the first character is a stop character, a start character value is obtained from the start character decode table 653. Since the second character is a data character, the start character decode table 652 or the start character decode table 653 has no character value at the corresponding address, so the data character decode table is referred to next. This reference refers to the data character decoding table 654 when the first character is a start character because the reading is in the forward direction, and refers to the data character decoding table when the first character is the reading in the backward direction when the first character is the stop character. The character value of the data is obtained with reference to the table 655.

Thereafter, this process is sequentially repeated to sequentially convert the data character portion of each bar code into a character value.

When the stop character value or the start character value is decoded from the stop character decode table 652 or the start character decode table 653 while the above decoding is repeated, it is determined that the barcode decoding is completed to the end, and the margin is finally determined. After the detection, the decoded output is transmitted.

In the present embodiment having such a configuration, for example, when the bar code shown in FIG. 8A is read in the forward direction, that is, from left to right, the pattern code of the first character is “3255”. From the start / stop character decode table (Fig. 3) 651 the character value "1"
03 ”is required and it is confirmed that it is a start character. In this case, since the last character should be a stop character, character values of the second and subsequent characters are decoded with reference to the stop character decode table 652 and the forward data character decode table 654. In the decoding of the last character, since the pattern code is "5642", the stop character decoding table (FIG. 4)
The character value “106” is obtained from 652, and it is confirmed that the character is a stop character.

Thus, decoding when the barcode is read in the forward direction is completed.

When the bar code shown in FIG. 8A is read in the reverse direction, that is, from right to left, the pattern code of the first character is "3224". "106" is obtained and it is confirmed that the character is a stop character. In this case, since the last character should be the start character, the character values of the second and subsequent characters are decoded with reference to the data character decode table 655 in the direction opposite to the start character decode table 653. Since the pattern code of the last character is “3552”, the start character decode table (No. 5)
From FIG. 653, the character value “103” is obtained, and it is confirmed that the character is the start character.

Thus, decoding when the barcode is read in the reverse direction is completed.

By the way, in the start / stop character decode table 651, the stop character decode table 652, and the start character decode table 653, the start character value “103” and the stop character value “106” are also located at the address position specified by the partially modified pattern code.
Is set.

Therefore, even if the pattern code is slightly deformed due to the end of the bar code digital signal input to the decoder due to the influence of a polarizer or an analog circuit when reading the bar code, that is, a part of the start character or the stop character is deformed, "2255""3155""3245""3254""3256" when the pattern code of the start character should originally be "3255" when reading in the forward direction
Even if the address is changed to "3265", "3355", or "4255", the start character value "103" is set in each address, so that decoding as a start character becomes possible.

The same can be said for the stop character decode table 652 and the start character decode table 653.

Since the start character and the stop character have a certain width in decoding as described above, the barcode reading efficiency can be improved. In addition, the start character and the stop character are different from the data portion that requires accuracy, and do not cause any problem as long as they are not confused with each other.

Also, since the last start / stop character decode table is separated into a stop character decode table 652 and a start character decode table 653, a larger number of character values can be set for the deformed pattern code than when they are combined into one. There is no possibility that the start character and the stop character are confused.

In the above embodiment, the case where the last start / stop character decode table is separated into the stop character decode table 652 and the start character decode table 653 has been described. However, the present invention is not limited to this. The decoding table may be a single decoding table such as a table 651. Further, the start / stop decode table 651, the stop character decode table 652, and the start character decode table 653 may be combined into one decode table.

In the above-described embodiment, the case where CODE128 is used as a barcode has been described. However, the present invention is not necessarily limited to this, and can be applied to barcodes of other code systems such as CODE93 and CODA BAR.

[Effects of the Invention] As described in detail above, according to the present invention, even if the digital signals corresponding to the start character and the stop character slightly change, the start table and the stop character can be decoded to the corresponding character values by the decode table. Therefore, it is possible to provide a barcode decoder and a barcode decoding method capable of improving the barcode reading efficiency.

[Brief description of the drawings]

1 to 6 show an embodiment of the present invention. FIG. 1 is a block diagram showing the structure of a decoder, FIG. 2 is a memory map of a character decode table, and FIG. 3 is a start / stop character. FIG. 4 is a diagram showing an example of setting a character value in a decode table, FIG. 4 is a diagram showing an example of setting a character value in a stop character decode table, FIG. 5 is a diagram showing an example of setting a character value in a start character decode table, and FIG. FIG. 7 is a block diagram of a bar code reading device, FIG. 8 is a diagram showing a relationship between a bar code pattern and a bar code digital signal, and FIG. 9 is a flowchart showing a decoding process by a conventional decoder. It is a flowchart shown. 63 …… RAM (random access memory), 64 …… CPU
(Central processing unit), 65 ROM (read only memory), 651 start / stop character decode table, 652 stop character decode table, 653 start character decode table, 6
54,655 ... Data character decode table.

Claims (4)

(57) [Claims] 1. A bar code consisting of a white bar and a black bar having at least two types of width values is replaced with a pattern code corresponding to the width of each white bar and black bar, and the decode table is referred to using the pattern code as an address. A bar code decoder that decodes each bar code character into a character value, wherein the decode table includes a start character and an address designated by a pattern code obtained by replacing an accurate bar code pattern of a start character and a stop character adjacent to a margin. In addition to setting the character value of the stop character, the character of the start character and the stop character are stored in an address specified by a pattern code in which a part of the start character and the stop character are transformed into a different pattern. A bar code decoder, wherein the character values of the start character and the stop character correspond to addresses designated by the plurality of pattern codes. 2. A bar code consisting of a white bar and a black bar having at least two kinds of width values is replaced with a pattern code corresponding to the width of each white bar and black bar, and the decode table is referred to using the pattern code as an address. When decoding each barcode character into a character value, the start character and the stop character are stored in an address designated by a pattern code obtained by replacing the correct barcode pattern of the start character and the stop character adjacent to the margin as the decoding table. The character values of the start character and the stop character are set at the address specified by the pattern code in which a part of the start character and the stop character are transformed into different patterns. A start / stop character decode table and a data character decode table in which a character value of a data character is set at an address specified by a pattern code obtained by replacing a bar code pattern of a data character interposed between a start character and a stop character; When decoding a barcode character, the start character and the stop character are decoded to a character value with reference to the start / stop character decode table, and the data character is decoded to a character value with reference to the data character decode table. A bar code decoding method. 3. A first start / stop character decode table and a last start / stop character decode table are provided as start / stop character decode tables, and the first start character or stop character in bar code reading is used as the first start / stop character. 3. The bar according to claim 2, wherein the decoding is performed to a character value by referring to a decoding table, and the last start character or stop character is decoded to a character value by referring to the last start / stop character decoding table. Code decoding method. 4. A final start / stop character decode table is separated into a start character decode table and a stop character decode table, and the start character decode table and the stop character decode table are selectively referred to in accordance with a bar code reading direction. The bar code decoding method according to claim 3, wherein the decoding is performed.