JP2786201B2 - Barcode demodulator - Google Patents

Description

[Contents] Outline Industrial application field Conventional technology (FIGS. 5 and 6) Problems to be solved by the invention (FIG. 7) Means for solving the problems (1st. Figure) Function Embodiment Effect of the Invention [Overview] Regarding a bar code demodulator, even if CB or GB is detected first in reading a left character or right character, even if a subsequent GB or CB is not detected, the condition is not changed. A bar code demodulator that reads a bar code in which multiple characters are interposed between guard bars or between a center bar and a guard bar, and demodulates the bar code, with the aim of improving the read rate by making data usable. In the apparatus, detecting means for detecting the guard bar or the center bar from the read barcode, and detecting the plurality of characters Demodulating means for sequentially demodulating from a character adjacent to the guard bar or the center bar detected by the step, and a sequence means for generating an output indicating that the final character of the barcode has been demodulated by the demodulating means, If an output is generated by the sequence means and the guard bar or center bar next to the last character is not detected, the bar code data is compared with the demodulated bar code data. The bar code data is made valid.

[Industrial applications]

The present invention relates to a bar code demodulator attached to, for example, food or miscellaneous goods, and particularly to a POS scanner, which improves the reading efficiency by conditionally validating demodulated data even if the last guard bar or center bar cannot be detected. It is.

[Conventional technology]

Bar codes include JAN (Japan), UPC (US), and EAN
(Europe) etc., but basically there are guard bars (GB) at both ends and a center bar (CB) at the center, with CB and GB
And a plurality of characters are written in bar codes. The bar code is scanned by a touch scanner, a gun scanner, or a fixed scanner by beam scanning and demodulated to read characters.

Each character is composed of seven modules. As shown in FIG. 5, a character on the right side of CB is called a right character, and a character on the left side is called a left character.

As shown in FIG. 6, the right character is composed of an even number (E) having a total of two or four modules of black module width. However, as shown in FIG. 6, the left character is composed of an odd number (O) having a total of three or five modules of black module width.
It is composed of a mixture of two or four modules of an even number (E). One example is shown in FIG.

Then, as shown in FIG. 5, the combination of the odd number (O) and the even number (E) of the left character is the thirteenth (in the case of 12 digits).
Is determined. In the example of FIG. 5, the 13th character is 4, and “49” combined with 9 of the twelfth character indicates that the barcode is in the JAN system. In FIG. 5, O and E on the left of the first to twelfth numbers indicate odd and even numbers.

Further, a modulus 10 check is performed to check whether or not the barcode is correctly demodulated.
The th character is the check character. Hereinafter, the modulus 10 check will be briefly described.

Even-numbered characters (2,
4, 6, 8, 10, 12th sum (5 + 1 + 0 in this example)
+ 4 + 2 + 9 = 21).

The sum of these is multiplied by three. This gives 21 × 3 = 63.

Odd number character sum (3
(3 + 1 + 1 + 4 + 0 + 4 = 13) from the th to thirteenth are obtained.

The above + is calculated. This gives 63 + 13 = 76.

Find the larger and nearest multiple of 10 and reduce it. This gives 80-76 = 4.

Check that the result of is equal to the first character.

By the way, a touch scanner or a gun scanner used when reading this barcode is one in which an operator aims at the barcode and scans it by beam scanning, and it is necessary to get used to the operation of these scanners. However, the fixed scanner has a fixed device and can be read only by moving goods on the fixed scanner. In addition, the scanner scans the beam in a plurality of directions, thereby enabling reading in all directions. Therefore, it is possible to read the product as if the product were moved from basket to basket without being conscious of the rotation angle of the barcode.

[Problems to be solved by the invention]

There are the following two types of bar code demodulation depending on the beam scanning direction.

(1) GB detection → character recognition → CB detection (2) CB detection → character recognition → GB detection Above (1) corresponds to the beam in FIG. 7, and (2) corresponds to the beam in FIG. These GB and CB are used as cutouts for character recognition. In the conventional demodulation method, only the characters sandwiched between GB and CB are valid, as in (1) and (2).

Therefore, when the GB and the character were correctly scanned as in the beam shown in FIG. 7, but the CB could not be accurately scanned, the CB was not detected because the CB was not detected. Similarly, in the case of the beam shown in FIG. 7, although it is possible to perform CB detection and character recognition, it cannot be validated because the last GB cannot be detected. Therefore, CB or GB
However, there is a problem that the reading rate is lowered because the character on one side is invalidated while being accurately scanned. In particular, such a tendency is likely to occur in reading a bar code attached to a round curved portion such as a can.

Therefore, an object of the present invention is to solve the above-mentioned problem by improving the reading rate by validating one that can be activated even when one of CB and GB is not detected.

[Means for solving the problem]

In order to achieve this object, in the present invention, FIG.
As shown in (1), a correlation check circuit 1, a GB or CB detection circuit 2, and a sequence circuit 3 are provided.

By the way, as shown in FIG. 1 (b), the bar code GB is composed of three modules of black and white and black, and as shown in FIG. 1 (C), the CB is composed of five modules of black and white and black and white. I have. Therefore, it is possible to detect GB or CB by detecting this pattern.

Further, the correlation check circuit 1 checks the final character length. Check the composition ratio of GB or CB adjacent to the last character. As shown in FIG. 1 (b), the next two modules of the final character (9 in this example) are assigned to T _n-2
Then, two modules one module after the first time of T _n−2 are defined as T _n−1 . The last character length since it is C _n-4, If successful _{2C n-4 7T n-1} , 2C n-4 7T n-2 is established.

GB can also be detected by checking the composition ratio of T _n-1 and T _n-2 of the δ distance.

The sequence circuit 3 is turned on when the demodulation of six digits is completed in the case of the standard barcode, and is turned on when the demodulation of half the four digits is completed in the case of the shortened barcode (8 digits). Is output.

Therefore, in the case of the standard barcode, "1" is output when the sequence circuit 3 completes the continuous demodulation of 6 digits, and "1" is output from the NAND gate 4 even if no GB or CB is detected at this time. Then, the AND gate 5 outputs “1” and the flag of the flip-flop (FF) 6
Turn on FLAG. Also, when demodulating a barcode, the above correlation check, that is, 2C _n-4 7T _n-1 or 2C _n-4 7T _n-2
Is not established, that is, the correlation check circuit 1 outputs "0".
Is output, the flag FLAG of FF6 is turned on if six digits are continuously demodulated and the sequence circuit 3 outputs "1". In this way, the flag FLAG of FF6 is turned on in the states of the items 3 and 4 in Table 1 below. By comparing the flag-on ones, the one with the same demodulation content between GB and CB can be used.

[Operation] According to the present invention, the data of items 3 and 4 in Table 1 are compared, and if the contents match, the data is made valid. First
It can be seen that items 3 and 4 in the table are the same when compared in order from GB. Of course, it is also possible to compare in the order from the CB to check whether they are the same.

In addition, when the six digits cannot be demodulated, it is invalidated as in the conventional case. Of course, in the case of a shortened barcode, it is only necessary to check the coincidence of four digits. Since the effective data can be converted in this manner, the barcode can be read efficiently.

〔Example〕

One embodiment of the present invention will be described with reference to FIGS.

FIG. 2 is a block diagram of an embodiment of the present invention, FIG. 3 is an explanatory diagram of a demodulation order, and FIG. 4 is an operation flowchart.

In FIG. 2, 10 is a barcode reading unit, 11 is a demodulation unit, 12 is a control unit, 13 is a demodulation data holding unit, 14 is an extraction unit,
Reference numeral 15 denotes a coincidence detecting unit, and 16 denotes a combining unit.

The bar code reading section 10 is an input section provided in the fixed scanner, and outputs a signal obtained by scanning a bar code as shown in FIG. 7 in other directions, for example, "0" for a white area and "1" for a black area. ".

The demodulation unit 11 demodulates the signal output from the barcode reading unit 10 to decode characters, CB, GB, and the like. Then, a barcode data holding unit 20 that temporarily holds barcode data transmitted from the barcode reading unit 10, a decoding unit 21 that decodes the barcode data, and a CB are detected.
A CB detection unit 22, a correlation check unit 23 for performing a correlation check described later, a GB detection unit 24 for detecting a GB, a sequence circuit 25 for detecting that four or six characters have been demodulated continuously, a NAND gate 26, 27, and gate 2
8, 29, 30, 31, 32, an OR gate 33, flip-flops F ₀ , F ₁ , F _{2 and the} like are provided. The operation of the demodulation unit 11 will be described later. Of course, the decoding unit 21 checks the module, and calculates the 13th character or the left character or the right character.

The control unit 12 comprehensively controls the entire fixed scanner to which the present invention is applied, and is constituted by, for example, a microprocessor.

The demodulation data holding unit 13 temporarily holds the demodulation data output from the demodulation unit 11, that is, the bar code reading result, and holds the demodulation contents as shown in Table 1 above, for example.

The extracting unit 14 selectively extracts the data of the items corresponding to the above Table 1 from the data held in the demodulated data holding unit 13. Of course, the extracting unit 14 can also extract the data of the third and fourth items. Select and extract.

The match detection unit 15 checks whether the data of the third term matches the data of the fourth term. For example, the match detection unit 15 determines whether the character following the third term GB (that is, the first character) Check for each character whether or not the sixth character of item 4 (that is, the last character) matches and whether or not the second character of item 3 matches the fifth character of item 4 Then, it is checked whether or not all the characters match. It is clear that the values match in the case of Table 1.

The synthesizing unit 16 synthesizes and outputs the left character output from the demodulation data holding unit 13 (of course, the 13th character is also provided) and the right character. The modulus 10 check is performed on the character output from the synthesizing unit 16, and when it is determined that the character is normal, processing based on this is performed.

 Next, the operation of the demodulation unit 11 will be described.

The CB detector 22 outputs, for example, “1” when detecting CB, and the GB detector 24 outputs, for example, “1” when detecting GB. The correlation check unit 23 checks the correlation between the last character and CB or the last character and GB. The CB detection in the CB detection circuit 22 is performed by detecting that five modules are configured in the order of “white, black, white, black, white” as shown in FIG. For example, T _n ′
It is detected by a method such as checking T _n-1 'T _n-2 '. The GB detection by the GB detection circuit 24 is performed by detecting that three modules are configured in the order of "black, white, and black" as shown in FIG. 3B. For example, it is detected by a method such as checking T _n-1 'T _n-2 '.

Further, the correlation check circuit 23 checks the composition ratio of the CB and the character, the characters, and the components adjacent to each other such as the character and the CB. For example, as shown in FIG.
In the last character and GB, C _n-4 is composed of 7 modules, and both T _n-1 and T _n-2 are 2 modules, so 2C
Check whether _n-4 7T _n-1 and 2C _n-4 7T _n-2 hold. Then, as shown in FIG. 3 (b), the final character
The CB also checks whether 2C _n− 47T _n−1 , 2C _n− 47T _{n−2, and the} like are satisfied.

Therefore, if the CB next to the last character cannot be detected in the case shown in FIG.
Alternatively, “1” is output when the correlation check between the final character and the CB is NG (when 2C _n− 47T _n−2 , 2C _n− 47T _n−7 , and 2C _n− 47T _n are not satisfied). Also Nand Gate 27
Is the GB following the last character in the case shown in FIG.
If is not detected, or correlation check of the last character and GB is the case of _{NG (2C n-4 7T n} -2, 2C n-4 7T n-1 may not hold) it is output "1". Therefore, at this time, when "1" indicating the completion of demodulation of the sixth character is output from the sequence circuit 25, the AND gate
28 or 29 outputs "1", the flip-flop F ₁ or F ₂ outputs a "1" indicating a flag-. Accordingly, in the case of the state shown in the third term of Table 1, the NAND gate 26 and the AND gate 28 output "1", and the flip-flop
F ₁ outputs “1”. In the case of the state of Table 1 paragraph 4 NAND gate 27, AND gate 29 outputs "1", the flip-flop F ₂ outputs "1".

The output of each of these flip-flops F ₁ and F ₂ is
The data is transmitted to the demodulation output 21 and the demodulated output is added with a term number such as the first to sixth terms as shown in Table 1 above and output to the demodulated data holding unit 13. Of course, the bar code is 8
In the case of a digit shortened bar code, the sequence circuit 25 is controlled to output "1" when demodulation of the fourth digit is completed.

Next, the operation of FIG. 2 will be described with reference to the flowchart of FIG. 4, in which the GB is checked first, but the CB after the last character cannot be detected, that is, FIG. 3 (b)
Such a case will be described.

(1) After the GB is detected, the first character is demodulated by the decoding unit 21. If the correlation check is not good at this time, the code is determined to be NG, and the demodulation process ends. However, if the correlation check is OK, the next character is demodulated.

(2) After the demodulation of the four characters is completed in this way, it is checked whether or not the next is a CB. In the case of a CB, the sequence circuit 25 outputs “1” because it is a case of a shortened bar code of 8 digits. If the check is OK, the AND gate 31 and the OR gate 33 become "1", and the AND gate 30 also outputs "1". Therefore, the flip-flop F ₀ outputs “1”, that is, the flag 0, and ends normally.

(3) However, if the CB cannot be detected, the fifth character is demodulated. If the correlation check is not established, the correlation check unit 23 outputs “0”. As a result, the NAND gate 26 outputs "1". At this time, the sequence circuit is 4
Outputs "1" at the end of character, so AND gate
28 is "1", the flip-flop F ₁ on That flag 1 is output. This is the standard barcode example
Corresponding to the case of the third item in Table 1, the decoding unit 21 adds the flag 1 and sends out the GB and the four characters decoded up to that time to the demodulation data holding unit 13, which is a so-called conditional end.

(4) By the way, in the case of the standard barcode, the correlation check is also OK when demodulating the fifth character. Further, the sequence circuit 25 is set by the decoding unit 21 by the demodulation of the fifth character. Next, if the correlation check is NG at the time of demodulation of the sixth character, the sixth digit is determined to be defective and abnormally terminated.

(5) However, if this correlation check is OK, the next is CB
Is detected. If it is CB, the flip-flop F _0, that is, the flag 0 is turned on, so that the decoding unit 21 adds the flag 0 and sends out the decoded 6 characters together with the GB to the demodulation data holding unit 13.

(6) If it is not CB, the NAND gate 26 outputs "1". At this time, since the sequence circuit 25 outputs "1" by demodulation of the sixth character, the AND gate 28 outputs "1". outputs ", the flip-flop F _1, that flag 1 is turned on, the decryption unit 21 with GB by adding a flag 1 sends the demodulated six characters in the demodulated data storage unit 13. In this way, the condition of the third item in Table 1 is conditionally terminated.

Although the above description has been made for the case corresponding to the third item in Table 1, the same applies to the case of the fourth item.

In this way, the cases of the third and fourth terms are also made valid data conditionally, so that they can be used as valid data when they are compared as above and a match is obtained.

〔The invention's effect〕

According to the present invention, when the last GB can not be detected even if the conventional GB is detected and character demodulation is performed, or conversely, the last GB is not detected even if the CB is detected and character demodulation is performed. The demodulated data that has been discarded can be used as a conditionally valid data with a simple circuit configuration.

As a result, the number of valid data increases, so that the reading rate can be improved.

[Brief description of the drawings]

 FIG. 1 is a diagram illustrating the principle of the present invention, FIG. 2 is a diagram illustrating the configuration of an embodiment of the present invention, FIG. 3 is a diagram illustrating a demodulation order, FIG. FIG. 6, FIG. 6 is an explanatory diagram of a bar code character, and FIG. 7 is an explanatory diagram of a bar code scanning state. 1 ... Correlation check circuit 2 ... GB or CB detection circuit 3 ... Sequence circuit 4 ... Nand gate 5 ... And gate

Claims (2)

(57) [Claims] 1. A bar code demodulator for reading a bar code in which a plurality of characters are sandwiched between guard bars or between a center bar and a guard bar, and demodulating the bar code, comprising the steps of: Alternatively, detection means for detecting the center bar; demodulation means for sequentially demodulating the plurality of characters from a character adjacent to the guard bar or the center bar detected by the detection means; and a final character of the barcode by the demodulation means. Sequence means for generating an output indicating that the demodulation has been demodulated.If the guard bar or the center bar next to the last character is not detected when the output is generated from the sequence means, the bar code data and And the demodulated barcode data A bar code demodulation device which compares the demodulated data as valid data when the values match with each other. 2. The bar code demodulator further comprises a correlation check for checking a correlation between a character demodulated by the demodulation means and an adjacent character, guard bar or center bar. The barcode demodulator according to claim 1.