JP2953143B2 - Barcode reading device and barcode reading method - 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 reader for improving erroneous reading based on printing errors of bar codes.

[0002]

2. Description of the Related Art FIG.
Is an explanatory diagram of a barcode with an add-on barcode, FIG. 7 is a diagram showing an example of the configuration of an add-on barcode section, and FIG. 8 is an explanatory diagram of a conventional demodulation method.

A bar code reader for reading a bar code with an add-on bar code will be described below as a conventional example. FIG. 5 shows an example of the configuration of a stationary bar code reader. A laser beam emitted from a laser 2 under the control of a laser control circuit 7 scans a bar code label 1 with an add-on bar code a plurality of times by an optical unit 3. The light reflected from the barcode label 1 is converted into an electric signal by the photodetector 4, amplified by the amplifier circuit 5, and binarized by the A / D circuit 6. And this binarized white /
The black signal (bar code data) is demodulated by the demodulation circuit 8 into character data,
It is sent to the S terminal.

[0004] In order to increase the amount of information, a barcode label 1 with an add-on barcode is provided, as shown in FIG.
Add a 2-digit (~) or 5-digit (~) add-on barcode to the main barcode, such as A (add-on)
As shown in FIG. 7, after a predetermined margin from the guard bar RGB of the main bar code portion, the character is repeated by repeating a character (SLGB) (special left guard bar), the first character, and then a DB (deliniate bar). Digits or five digits are configured. The final character is a character and does not have a guard bar or the like unlike the main bar code portion.

FIG. 8 shows an example of a conventional demodulation method, in which 7 modules (a unit length is called a module).
The DB composed of a character and a black bar represented by one module is analyzed, and the delta distance length (the distance between the edges of the white bar or the black bar and the number of modules) T1 shown in FIG. And T2, and demodulates the barcode data into character data with reference to the demodulation table A. At this time, as shown in FIG. 8, like EVEN2 and EVEN8, ODDs 1, 2, 7, 8 and EVE
N 1, 2, 7, 8 (hereinafter collectively referred to as 1728)
Since it is not possible to discriminate between T1 and T2, the number of modules having the black bar widths B1 and B3 is calculated, and the 1728 portion is discriminated with reference to the demodulation table B. Since the character is defined as seven modules, it is possible to measure and demodulate only B3, but demodulation using B1 and B3 reduces misreading.

[0006]

A bar code is read 2
When converting into a value, as shown in the problem explanatory diagram of FIG. 9, a black edge signal and a white edge signal which are transition points of a white / black bar are detected, and a barcode signal is reproduced. Therefore, if there is a change in the white level, a black edge signal is generated, and a signal different from the original bar code signal may be reproduced.

FIG. 9 shows a case where a bar code with an add-on bar code is scanned from the add-on side. If the white level of the bar code label is closer to the black level than the white level of the attached product, the label and the product are displayed. A black edge signal is generated at the boundary of. In this case, since the guard bar does not exist at the end of the add-on bar code, the black signal B1 of the last character becomes fat. This is because if there is a guard bar, a white edge signal is output at the edge of the guard bar, and the black bar of the character is normally detected, but in the case of add-on, there is no white edge signal by the guard bar, so the final black of the final character This is because B1 is detected to be substantially fat because the reproduced barcode signal is continuously output until the white edge signal is output by the bar. Therefore, demodulation cannot be performed by the conventional demodulation method of 1728 using B1 / B3.

To solve this, as described above, 1
The portion 728 may be demodulated using only the number of B3 modules. However, depending on the current state of printing technology, standards, and the like, an error may easily occur in the B3 width and there is a possibility of erroneous reading.

In view of the above problems, it is an object of the present invention to provide a bar code reader and a reading method that can accurately demodulate even when scanning is performed from the add-on side.

[0010]

FIG. 1 is a diagram showing the principle of the present invention. In the diagram, reference numeral 30 denotes an arithmetic unit, which is a predetermined section of a delta distance length which is a distance between edges of adjacent white bars or black bars in a bar code. A delta distance length and a delta distance length of a predetermined section from a predetermined bar to the bar code are calculated. A demodulation unit 31 demodulates the barcode based on the calculated delta distance length.

In particular, a bar code demodulator for demodulating a main bar code portion of a bar code with an add-on bar code, an add-on bar code demodulator for demodulating the main bar code portion, and identifying and demodulating the add-on bar code portion. In the bar code reading device having, when the bar code data is input from the add-on bar code portion side, among the plurality of digits of the characters constituting the add-on bar code portion, at least the last digit character using the delta distance length The add-on barcode demodulation unit is configured to perform demodulation.

In the above bar code reading device, when the character width of the last digit is larger than a predetermined value, the add-on bar code demodulation unit recognizes the add-on bar code with the add-on bar code input from the add-on side and uses the delta distance length. And demodulate.

In one reading operation, a bar code with an add-on bar code is demodulated two or more times, and if it matches, the reading is successful.

[0014]

The present invention has been made by paying attention to the fact that the delta distance length is higher in accuracy than the bar width in both the standard and the printing technology.

In FIG. 1, a calculation unit 30 includes a predetermined delta distance length (T1, T2 in FIG. 1) which is a distance between edges of adjacent white bars or black bars in a bar code, and a bar code following the predetermined bar. And a predetermined delta distance length (T4 in FIG. 1), and the demodulation unit 31 demodulates barcode data using the delta distance lengths T1, T2, and T4. As a result, compared with the case of demodulation using the black bar width, in particular, 17
Misreading of 28 parts can be reduced.

Hereinafter, the present invention will be specifically described with reference to FIG. FIG. 2 shows the demodulation of the add-on barcode section.
This shows a case where EVEN 2 (hereinafter E2) and EVEN 8 (E8) are identified, and both are T1 = T2 = 3 modules (see demodulation table A in FIG. 8). For this reason, conventionally, the number of modules B3 and B1 (E2 is two modules, E8 is one module) is measured and the demodulation table B is referred to, but the printing error ΔB3 of the black bar is, for example, 0.5
If it is larger than the module, it will be rounded off and E3 B3
Is 2 and it is difficult to distinguish from E2. According to FIG. 2, B3 = T3-W4 = T3- (T4-B5) and B5 = 1 module, so that B3 = T3-T4 + 1. Here, since T3 = 7−T1, T1, T1
2, T4 can be used for demodulation, and misreading can be greatly reduced as compared to demodulation using a black bar width having a larger printing error. In particular, when the scanning is performed from the add-on side and the black bar is widened, the effect is great.
In FIG. 2, T4 of E2 is 3 modules, and T4 of E8 is
Is four modules.

In a stationary bar code reader using a laser or the like, bar code data is input a plurality of times by one operation. Therefore, in one reading operation, the same add-on bar code-added bar code is read twice. If the reading is successful when the signals are demodulated and coincide with each other, the reading accuracy can be further improved.

[0018]

FIG. 3 is a block diagram of one embodiment, and FIG. 4 is a flowchart of a demodulation process. In the present embodiment, an example in which the present invention is applied to the demodulation of the last digit of an add-on bar code portion in a bar code reading device that reads a bar code with an add-on bar code is shown.

In FIG. 3, a demodulation unit 12 extracts a main bar code portion from a bar width counter data buffer 20 and demodulates the data by referring to demodulation tables A and B. After the partial demodulation, the add-on barcode demodulator 1 extracts the add-on barcode portion and demodulates the data by referring to the demodulation table A and the demodulation table C.
6. Buffer 15 for storing demodulated data (demodulation code), check unit 18 for performing various checks on demodulation code
Etc. Reference numeral 19 denotes a bar code recognition unit, a bar width counter 23 for measuring a bar width of A / D conversion data of the bar code input from the optical system, a bar width counter data buffer 20 for storing bar width counter data, and a buffer counter. A pointer indicating buffer 22 for storing a pointer for indicating a storage address of the data buffer 20, and a buffer control unit start / stop detection circuit for detecting that the count data is a barcode, and controlling and storing these buffers. It is composed of 21 mag. 26 is PO
DVRV 27 is an interface unit with the S terminal device, and is an interface driver and receiver circuit. Reference numeral 11 denotes a processor CPU which controls each unit.

The demodulation table A and the demodulation table B
Is the same as that shown in FIG. 8, and the demodulation table C is, as shown in FIG. 4, associated with the number of T4 modules for demodulated data to be superimposed.

In the bar code reader having the above-described structure,
The following demodulation processing is performed. See FIGS. 2, 3 and 4. (1) The bar width counter 23 measures the bar width of the binarized data input from the optical system. (2) The buffer control unit start / stop detection circuit 21
When a predetermined white margin, guard bar, or the like is detected from the bar width of the binarized data and recognized as a bar code signal, the bar width counter data measured by the bar width counter 23 is stored in the bar width 20 for the bar width counter data. Is stored in the pointer instruction buffer 22. At this time, DB, S
The add-on barcode portion is recognized by LGB or the like. If the character width of the last digit is B1 and the predetermined digit is 7 modules or more, the add-on barcode portion is recognized as a barcode with an add-on barcode input from the add-on side. I do. (3) The main barcode demodulation unit 14 extracts the main barcode portion from the bar width counter data buffer 20, measures the delta distance lengths T1 and T2, and
, And demodulate. At this time, in the case of 1728, B3 and B1 are measured and the demodulation table B is referred to for identification as in the past. (4) When the demodulation of the main barcode section is completed, the add-on barcode demodulation section 16 extracts the add-on barcode section,
The demodulation is performed by referring to the demodulation table A based on the delta distance lengths T1 and T2. At this time, in the case of 1728, B3 and B1 are calculated similarly to the demodulation of the main bar code portion,
The demodulation is performed with reference to the demodulation table B. For the data input from the add-on side and the data of the last digit, the delta distance length T4 (see FIG. 2) from the delineate bar DB is calculated, and the demodulation table C is used. Demodulate. (5) When demodulation is completed, the check unit 18 performs various checks on the demodulated data, and if normal, transmits the data to the POS terminal device. In addition, if the barcode with the add-on barcode is checked, particularly when the same barcode is input, that is, when the demodulation is successful two or more times, the erroneous reading is further improved.

As described above, since the last digit of the add-on bar code is demodulated using the delta distance length from the DB, normal demodulation can be performed even when the black bar of the last digit input from the add-on side is thick (thin). Can be.

In the above description, the example in which the present invention is applied only when data is input from the add-on side has been described. However, the present invention can also be applied to demodulation of the main bar code portion and demodulation of other digits of the add-on bar code portion. Of course, the present invention can be applied to a barcode without an add-on barcode.

[0024]

As described above, according to the present invention, the demodulation of the 1728 portion of the bar code is demodulated using the delta distance length from a predetermined bar serving as a printing reference.
The effect of improving reading accuracy due to printing errors is significant.

[Brief description of the drawings]

FIG. 1 is a principle diagram of the present invention.

FIG. 2 is an explanatory view of the present invention.

FIG. 3 is a configuration diagram of one embodiment.

FIG. 4 is a flowchart of a demodulation process.

FIG. 5 is a configuration diagram of a barcode reader.

FIG. 6 is an explanatory diagram of a barcode with an add-on barcode.

FIG. 7 is a diagram showing an example of a configuration of an add-on barcode unit.

FIG. 8 is an explanatory diagram of a conventional demodulation method.

FIG. 9 is an explanatory diagram of a problem.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 bar code label with add-on barcode 2 laser 3 optical unit 4 photodetector 5 amplifier circuit 6 A / D circuit 7 laser control circuit 8 demodulation circuit 9 scanner control circuit 10 interface section 11 CPU 12 demodulation section 14 main barcode demodulation section 15 Buffer 16 Add-on barcode demodulation unit 18 Check unit 19 Barcode recognition unit 20 Bar width counter data buffer 21 Buffer control unit start / stop detection circuit 22 Pointer instruction buffer 23 Bar width counter 26 Interface unit 27 DVRV 30 Operation unit 31 Demodulation unit A, B, C Demodulation table

Claims (4)

(57) [Claims] 1. A bar code reader for optically reading a bar code having an add-on bar code attached to one end of a main bar code, comprising: a demodulator for demodulating input bar code data; When barcode data is input from the add-on barcode side, demodulation of at least the first input character among the characters of the add-on barcode is the distance between edges of a black bar and a white bar adjacent to each other. A bar code reader, wherein demodulation is performed using a delta distance length. 2. When the width of a character input first is larger than a predetermined position, the input bar code data is recognized as a bar code input from an add-on bar code side and demodulation is performed. The bar code reader according to claim 1, wherein 3. The barcode reader according to claim 2, wherein in one reading operation, if two or more sets of demodulated data of a barcode with an add-on barcode match, the reading is successful. 4. An add-on bar code is added to the main bar code.
To read barcodes with add-on barcodes marked with
In the law, Determine the direction of the input barcode data, The input barcode data is on the add-on barcode side
If it is determined that the barcode data is input from
At least one of the add-on barcode characters
The demodulation of the character entered at the beginning
Delta distance, the distance between the edge of the bar and the black bar
Barcode reading characterized by performing based on the length of the barcode
apparatus.