JPH02302887A - Method for discriminating sort of bar code for bar code reader - Google Patents

Abstract

PURPOSE:To reduce the size and cost of a bar code reader by using the average of the maximum bar width and the minimum bar width as a decision reference value to decide the sort of a bar code. CONSTITUTION:A CPU 9 reads out the initial data from a RAM 11, executes margin check and repeats the operation until the candidate of the left margin is retrieved. When the left margin candidate is retrieved, four data every other data from the succeeding data, i.e. the 1st to 4th black bar width data are read out and the maximum value MXB and the minimum value MNB are found out. The values are compared with each other, and when MXB/MNB is less than a fixed value, all the black bars are narrow width is judged and binary '0's are allocated to all the black bars. Thus, binary data of 6 bits or 7 bits consisting of 3 or 4 black bars an 3 white bars are found out and the sort of the bar code is decided by the binary data. Consequently, the size and cost of the device can be reduced and the processing time for discrimination can be shortened.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to a barcode type discrimination method for a barcode reader, and particularly to a binary level barcode consisting of a black bar and a white bar having two widths. Concerning a method for determining the type of.

[Prior art] Barcodes have 4 codes called JAN, EANSUPC, etc.
Barcodes consisting of black bars and white bars with different widths, NW 7 (Coda bar), COD E39,
I-T F (Infer 1eaved2 of
There is a binary level barcode consisting of a black bar and a white bar with two types of widths, called 5).

Among these, looking at the binary level barcode, NW7
As shown in Figure 5, one character consists of four black bars and three white bars, and each character is separated by a white bar called an intercharacter gap.
It has four types of start and stop characters that indicate the beginning and end of barcode data. This start character and stop character are rAJ
rBJrCJ Represented by the letters rDJ.

For each character, 2 or 3 of the 7 bars are wide bars, and especially for the start character and stop character, 2 of the own bars and 1 of the black bars are wide wide bars. ing.

For CO and DE39, as shown in Figure 6, one character consists of five black bars and four self-bars, and each character is separated by a white bar called an intercharacter gap. It has a start character and a stop character represented by the symbol "*" indicating the beginning and end. Each character has nine bars, three of which are wide bars.

In the ITF, as shown in Figure 7, one character consists of five black bars or five white bars, and 10 bars in an alternating combination of these represent 2 data characters, and the gap between characters is Instead, two of the five black bars and the own bar are wide bars. The start pattern indicating the beginning of barcode data is a narrow bar consisting of two black bars and two own bars, and the stop pattern indicating the end of barcode data is two black bars and one narrow bar. It consists of white bars of books, and one of the black bars is a wide bar.

The above is summarized in a table as shown in Table 1.

The conventional barcode reading device for reading these three types of barcodes with different systems was Japanese Patent Application Laid-Open No. 1983-1945.
78, JP-A-63-91792, and JP-A-63-228277 are known.

The device disclosed in Japanese Patent Application Laid-open No. 194578/1983 provides three types of demodulation processing means for independently decoding three types of barcodes, and operates each demodulation processing means simultaneously for reading a certain barcode. However, the decoding is performed by one of the demodulation processing means.

In the method disclosed in Japanese Patent Application Laid-open No. 63-91792, when barcode data is read, a decoding processing flag is read, and the decoding processing flag determines the priority of the decoding processing and decoding is performed. The decoding is performed sequentially.

The method disclosed in Japanese Patent Application Laid-Open No. 63-228277 sequentially examines the same number of bars as the start symbol of each barcode data to check whether they match any one code system, and when a matching code is found, it The corresponding decoding process is performed.

However, in JP-A No. 61-194578, 3
Since different types of demodulation processing means are provided for simultaneous processing, the CPU
There was a problem in that the amount of hardware such as hard disks and hard decoders increased, making it impossible to downsize the device and reduce costs.

In addition, 1 in Japanese Patent Application Laid-Open No. 63-91792 is
To demodulate a barcode, the maximum time required is (the time required to demodulate one code) x (the number of readable code types), and the manual scanning type has relatively sufficient demodulation time. However, in a laser scanning type barcode reader where barcode reading is performed at high speed, there is a risk that the demodulation process will not be completed in time, resulting in a problem of lowering the reading rate.

Furthermore, in the method disclosed in Japanese Patent Application Laid-open No. 63-228277, only the start pattern of each code is checked, so the processing time can be reduced compared to those in other publications. Since the tests were conducted sequentially, it was not sufficient to sufficiently shorten the processing time. Also, in this publication, ITF (interleaved 2 or 5)
) There was a problem that the barcode could not be identified.

[Problems to be Solved by the Invention] As described above, in the conventional barcode discrimination method, it has not been possible to reduce the size and cost of the device, and to sufficiently shorten the processing time for discrimination.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a barcode type discrimination method for a barcode reading device, which can reduce the size and cost of the device, and can sufficiently shorten the processing time for discrimination.

[Means and effects for solving the problem] The present invention provides a barcode reading device that converts each bar width of a scanned and read barcode into a count value, and demodulates barcode data from the count value. The maximum bar width MXB and minimum bar width MNB of the black bar and the maximum bar width MXW and minimum bar width MNW of the white bar are calculated from 3 or 4 black bars and 3 white bars counting from the black bars adjacent to the part. When M X n / M N s is less than a preset constant value, all black bars are made to correspond to binary "0", and when it is greater than a certain value, the black bar width is determined by the criterion value. (MXB + MNa)/2 is calculated, and the judgment reference value is compared with each black bar width, and a binary "1" is assigned to a black bar wider than the judgment reference value, and a black bar narrower than the judgment reference value is calculated. Binary “0”
, and when M
0", and when it is above a certain value, find the judgment standard value of the white bar width by (MXw + MNw) / 2, compare the judgment standard value with each bar width, and select the own bar width that is wider than the judgment standard value. A binary number "1" is made to correspond to a binary number "1", and a binary number "0" is made to correspond to a white bar narrower than the judgment reference value, thereby creating a 6-bit result consisting of three or four black bars and three white bars. Alternatively, the method involves obtaining 7-bit binary data and determining the type of barcode based on this binary data.

Then, when the 7-bit binary data is "001010o" or the 6-bit binary data is "001010", count the total number of bars sandwiched between the left and right margins, and the total number of bars is (5n + 71 (however, n is a positive integer), the barcode type is set to ITF (interleaved 2o
f5), and the total number of bars is ilO(n+2)
11 (where n is a positive integer), the type of barcode is determined to be C0DE39.

Also, when the 7-bit binary data is r0011010 or the 6-bit binary data is rollolJ, count the total number of bars sandwiched between the left and right margins, and the total number of bars is (5n + 7) (where n is positive). When the total number of bars matches only (8(n+2)-11 (where n is a positive integer)), the barcode type is determined to be ITF (interleaved 2 of 5). The type of code is determined as NW7 (Korg bar), and (5n+7) and (8(n)
When both +2) and -1) match, the right start/stop pattern is further checked to determine whether it is ITF or NW7.

In this way, even if the start character of C0DE39 is read in the opposite direction and the ITF stop pattern cannot be distinguished, the difference can be made by counting all the bars sandwiched between the left and right margins. becomes possible. Also NW7's start characters A and IT
Even if the stop pattern of F cannot be distinguished, it can be distinguished by counting all the bars between the left and right margins, and if it is still not possible to distinguish it, by further examining the start/stop pattern on the right side. It becomes possible to differentiate.

[Example] Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing a barcode reading device, in which a laser beam emitted from a laser emitting unit 1 scans a barcode label 2 on which a barcode is printed via a scanning means (not shown). The reflected light is received by the light receiving section 3 and converted into an electrical signal. The electric signal from the light receiving section 3 is amplified by an amplifier circuit 4, and further converted into a digital signal by a binarization circuit 5.

The bar width counter 6 measures the time width between the rising edge and the falling edge of the digital signal and between the falling edge and the rising edge by counting the clocks from the clock generator 7. That is, the bar width counter 6 converts the bar widths of the black bar and white bar of the barcode into time width data consisting of the number of clocks. Each time width data counted by this bar width counter 6 is supplied to an input port 8.

Reference numeral 9 denotes a CPU (central processing unit) that constitutes the main body of the control unit, and this CPU 9 controls each part and demodulates barcode data based on program data in a ROM (read only memory) 10. The CPU 9 stores each time width data input to the input port 8 in a RAM (random access memory) 11.
I am trying to store them sequentially.

Further, the CPU 9 sequentially reads out each time width data stored in the RAMII, demodulates the barcode data, and sends the result to an external device 13 such as a host computer via the external interface 12, and also outputs the output port 14. The image is outputted to the display device 15 via the display device 15.

The CPU 9 is programmed to determine the type of barcode read based on FIGS. 2 to 4.

That is, as shown in FIG. 2, the CPU 9 reads the first data from RAMII and performs a margin check, and continues this until a left margin candidate is found. When a left margin candidate is retrieved, every other four pieces of data, that is, the first to fourth black bar width data, are read out from the next data, and their maximum value MX and minimum value MN are determined.

Then, compare the maximum value MXB and the minimum value MNB, and MXB/
If MNB is less than a certain value, it is determined that all black bars have a narrow width, and a binary number "0" is assigned to all black bars. Note that the constant value at this time is determined by the reading conditions, analog circuit, optical system characteristics, etc., and is, for example, 1.5.
It is set to a certain degree.

Furthermore, if M X a / M N B is above a certain value, the determination reference value THB is determined by THB - (MXB + MNB )/2,
The width of each black bar is compared with its judgment reference value THB, and if it is greater than or equal to the reference value, it is determined that it is a wide bar and a binary number "1" is assigned to it, and if it is less than the reference value, it is determined that it is a narrow bar. Assign the binary number "0".

Next, the width data of the three white bars sandwiched between the first to fourth black bars is read out, and its maximum value MXw and minimum value MNw are determined.

Then, the maximum value MXW and the minimum value M N w are compared, and M
If X w / M N w is less than a certain value, it is determined that all white bars have narrow widths, and a binary number rOJ is assigned to these all white bars.

Also, if M X w / M N w is above a certain value, determine the judgment reference value THW by THw - (MXW + MNW ) / 2, compare each bar width with the judgment reference value THw, and if it is above the reference value. If it is determined that it is a wide bar, a binary number "1" is assigned to it, and if it is less than the reference value, it is determined that it is a narrow bar and a binary number "0" is assigned to it.

1 In this way, find a 7-bit binary number consisting of 4 black bars and 3 white bars.

Then, by referring to the code type discrimination table shown in Table 2 provided in ROMI O, this binary number is set to NW7, C.
It is determined which code is 0DE39 or ITF.

-18= In this Table 2, "upper" indicates the upper 3 bits, and "lower" indicates the lower 4 bits. Also, I is I
TF, N is NW7, C is C0DE39, I-C is ITF
or C0DE39 and I-N indicate ITF or NW7, respectively. Furthermore, the subscript F indicates forward reading, and the subscript B indicates backward reading.

In this determination, if the upper rank is "1", that is, roolJ, and the lower rank is "4", that is, ro 100J, then rl-
There are times when it is not possible to distinguish between ITF and C0DE39 using Cl, and in this case, the process shown in FIG. 3 is further performed.

In this process, first, it is checked whether the 18th data counting from the first margin (left margin) is the right margin or not, and if it is the right margin, it is determined that it is ITF. If it is not a margin, then it is checked whether the 28th data is a right margin or not, and if the right margin is 1, it is determined that it is an ITF. Further, if it is not a margin, it is further determined whether the 29th data is a margin or not, and if it is a margin, it is determined as C0DE39. In this way, if there is a margin at t5n+81, it is determined to be ITF, and if there is a margin at (10(n+2)), it is determined to be C0DE39. However, n-1,
2, 3,...

Note that if the margin cannot be detected even if the number of characters reaches the preset maximum number of readable digits of data characters, it is determined that neither code exists and an error is generated.

This process in Fig. 3 means that the total number of bars in the ITF is (5n + 7
), and the total number of bars of C0DE39 is (10(n+2)
-1).

Also, in this discrimination, the higher rank is "1", that is, roo
When the lower rank of lJ is "A", that is, rl 010J, it is when r, I-NJ cannot distinguish between ITF and NW7, and in this case, the process shown in FIG. 4 is further performed.

In this process, first, it is checked whether the 18th data counting from the first margin (left margin) is the right margin or not, and if it is the right margin, it is determined that it is ITF. If it is not a margin, then it is checked whether the 24th data is a right margin or not, and if it is a right margin, it is determined to be NW7. Also, if there is no margin, if there is a margin at the (5n+8)th position, it is separated from the ITF, and if there is a margin at the (8(n+2)lth) position, it is determined to be NW7.However, n = 1.2゜3, ・
It is...

Also, even if there is a margin at 5n+81st, if n is a multiple of 8, this also applies to the number of bars in NW7, so in this case, check the second to last white bar and if it is a wide bar, determine it as NW7, Further, if it is a narrow bar, it is determined that it is an ITF.

In this case as well, if the margin cannot be detected even if the number of characters reaches the preset maximum number of readable digits of data characters, it is determined that neither code exists and an error is generated.

The process shown in FIG. 4 is based on the fact that the total number of bars in ITF is (5n+7) and the total number of bars in NW7 is (8(n+2)-11).

In this embodiment with such a configuration, when the first margin candidate is detected, the widths of the four black bars next to that margin and the widths of the three white bars in between are checked, and the maximum black bar width is determined. Value MXB, minimum value MNB, and maximum value MXW of own bar width
and find the minimum value MNW.

Regarding the black bars, if M X n / M N n is less than a certain value, all black bars are set to "0", and if it is above a certain value, the judgment reference value THB is set to (MX).

+MNn)/2, and "1" or "0" is determined by comparing this reference value TH13 with each black bar width. Similarly, regarding the white bars, if MXW/MNW is less than a certain value, all white bars are set to "0", and if it is above a certain value, the judgment reference value T Hw is set to (MXW+MNW)/
2, and determine "1" or "0" by comparing each bar and width with this reference value THw.

The 7-bit binary number obtained in this way is referred to the barcode type discrimination table stored in the ROM 10 to determine whether it is an ITFSCODE39 or NW7 type, and when the type is determined, it is barcoded based on the corresponding demodulation program. Demodulation of the code data is performed.

The width of the 7 bars, 4 black bars and 3 white bars, adjacent to the margin of the barcode read in this way is rD.
j rlJ into binary numbers, the binary data is referred to a table to determine which code type it is, and the corresponding demodulation process is performed, so three types of barcodes are sequentially examined and determined. Code discrimination time can be shortened compared to those that do. Therefore, it is possible to shorten the time from reading the bar hood to demodulating it, and it is sufficient to cope with laser scanning type high-speed scanning.

Further, when the binary data is "001010oJ", it is not possible to distinguish between ITF and C0DE39 in the table.

In this case, counting from the left margin, which is the first margin, (5n-1-gl) If there is a margin, it is determined as ITF and demodulation processing is performed.
If there is a margin, it is determined to be C0DE39 and demodulation processing is performed.

Further, when the binary data is ro 011010J, it is not possible to distinguish between ITF and NW7 in the table. In this case, count from the first margin, the left margin (
If there is a margin at 5n+8), it is determined to be ITF and demodulation processing is performed, and if there is a margin at 8(n+2)l, demodulation is performed separately from NW7.However, in this case, there was a margin. When the value of n is a multiple of 8, it is impossible to distinguish between ITF and NW7, so in this case, the second-to-last white bar is further checked, and if that white bar is a wide bar, it is determined to be NW7, and if it is a narrow bar, it is determined that it is NW7. If so, it is determined that it is ITF.

In this way, even for the two special binary data, ITF, C0DE39, and NW7 can be determined with certainty. Therefore, demodulation processing corresponding to each barcode type can be reliably performed.

In addition, since the corresponding demodulation program is read out based on the results of this discrimination and the demodulation process is performed, the hardware configuration is simpler compared to a system that operates three demodulation means at the same time, and the device can be made more compact. It is also possible to reduce costs.

In addition, for a total of 5 bars (3 black bars and 2 white bars), the widths of the all black bars and all white bars may be equal, and in that case, it is difficult to determine whether it is a wide bar or a narrow bar. It becomes impossible to realize this because discrimination becomes impossible.

Further, eight or more bars include the NW7 gear-to-gear character, which is not preferable because an error may occur when determining the white bar width determination reference value, resulting in incorrect determination.

In the above embodiment, a total of seven bars, four black bars and three white bars, are read out from the RAM and converted into binary data to determine the code type, but the present invention is not necessarily limited to this. Instead, the same processing can be performed by reading a total of six bars, three black bars and three white bars, and converting them into binary data.

Further, in the embodiment described above, the barcode type determination is performed by software processing by the CPU, but the invention is not necessarily limited to this, and may be configured by hardware logic.

[Effects of the Invention] As detailed above, according to the present invention, there is provided a barcode type discrimination method for a barcode reading device that can reduce the size and cost of the device, and can sufficiently shorten the processing time for discrimination. It is possible to provide

[Brief explanation of the drawing]

1 to 4 show embodiments of the present invention.
The figure is a block diagram, Figures 2 to 4 are flowcharts showing barcode type discrimination processing by the CPU, Figure 5 is a diagram showing the barcode pattern of NW7, Figure 6 is a diagram showing the barcode pattern of C0DE39, FIG. 7 is a diagram showing an ITF barcode pattern. 6... Bar width counter, 9... CPU (Central Processing Unit), 10... ROM (Read Only Memory), 1
1...RAM (Random Access Memory).

Claims (3)

[Claims] (1) In a barcode reading device that converts each bar width of a scanned barcode into a count value and demodulates barcode data from the count value, three or more black bars are counted from the black bar adjacent to the margin area. Maximum bar width MX of black bar from 4 black bars and 3 white bars
_B and minimum bar width MN_B and maximum bar width MX of white bar
Find _W and minimum bar width MN_W, and calculate MX_B/MN_
When B is less than a preset constant value, all black bars are made to correspond to binary ``0'', and when it is above a constant value, the black bar width judgment standard value is determined by (MX_B + MN_B)/2. The judgment reference value is compared with each black bar width, and a black bar wider than the judgment reference value is associated with a binary ``1'', and a black bar narrower than the judgment reference value is associated with a binary digit ``0''. , Also, when MX_W/MN_W is less than a preset constant value, all white bars correspond to binary "0", and when it is greater than a certain value, the white bar width judgment reference value is (MX_W
+MN_W)/2 and compares the judgment reference value with each white bar width, and assigns a binary number "1" to the white bar wider than the judgment reference value and a binary number to the white bar narrower than the judgment reference value. ``0'' of ``0'' corresponds to the ``0'', thereby obtaining 6-bit or 7-bit binary data consisting of 3 or 4 black bars and 3 white bars, and converting these 2
1. A barcode type determination method for a barcode reading device, characterized in that the barcode type is determined based on digit data. (2) When the 7-bit binary data is "0010100" or the 6-bit binary data is "001010", count the total number of bars sandwiched between the left and right margins, and calculate this total number of bars as {5n+7} (where n is a positive integer), the barcode type is set to ITF (interleaved 2o).
f5), and the total number of bars is {10(n+2)-1
} (where n is a positive integer), the type of barcode is determined to be CODE39 (
1) Barcode type determination method of the barcode reading device described above. (3) When the 7-bit binary data is "0011010" or the 6-bit binary data is "001101", count the total number of bars sandwiched between the left and right margins, and calculate this total number of bars as {5n+7} (where n is a positive integer), the barcode type is determined to be ITF (interleaved 2 of 5), and the total number of bars is {8(n+2)
)-1} (where n is a positive integer), the barcode type is determined to be NW7 (coda bar), and it also matches both {5n+7} and {8(n+2)-1}. 2. The barcode type determination method for a barcode reading device according to claim 1, further comprising checking a right start/stop pattern to determine whether it is ITF or NW7.