JP2005128626A - Barcode reader and barcode discriminating method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a barcode reader which hardly causes read errors of barcodes. <P>SOLUTION: The barcode reader sets three subsets for decoding, consisting of four successive elements in one character of CODE128, while shifting them by one element each, finds totals of width values of elements belonging to the subsets (a), (b), and (c), and discriminates the one character, on the basis of the ratio of the total values. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a barcode reading apparatus and a barcode discrimination method for reading a barcode in which two adjacent elements each have three or more types of width values and one character is composed of six or more elements.

  FIG. 7 shows an example of the CODE 128, which is one type of barcode. In CODE 128, two adjacent elements, bar and space, each have four types of width values, and one character is expressed by 11 modules (unit width dimensions) including three bars and three spaces. Also, since there are three types of start codes and ASCII 128 characters can be expressed by correspondence between each start code and 103 types of code patterns, it is called CODE128. Further, since the start code C can express a 2-digit number with one character, it is possible to increase the printing density of the barcode. Furthermore, the sum of the number of modules used for each bar and space is even parity and odd parity, and an error check function is also provided.

In Patent Document 1, there is no limitation on the scanning speed of the reader for adjacent barcodes each having four or less types of width values such as CODE128, and the width of the element is slightly increased or decreased. A method for accurately recognizing codes is also disclosed.
Japanese Patent Publication No. 7-62858

  By the way, in recent years, a smaller barcode is required. If the size of the bar code is made smaller, if the bar or space becomes thicker or thinner due to printing “smearing” or the like, the effect becomes larger, and the width of the bar or space cannot be specified accurately. That is, there is a problem that a barcode reading error is likely to occur. In addition, since the barcode is optically read, the width of the bar or space gradually increases in the reading direction when the reading angle is inclined or the barcode is not flat. Or may be read in a thinned state.

  In the method disclosed in Patent Document 1, the following procedure is used in order to specify the widths of bars and spaces. The bar code is scanned, a value corresponding to each area width of the bar and space is stored as a count value, and a total value for each character is calculated based on each count value. Then, if the quotient of the total value and each count value is obtained and used as a calculated value, the width value of each bar and space, that is, two values according to the magnitude relationship between the calculated value and the first, second, and third comparison values. Determine the decimal value. Here, the first, second, and third comparison values are set as follows.

<First comparison value>
A substantially intermediate value between the quotient of the total value and the count value of the bar or space for one module and the count value of the bar or space for two modules.
<Second comparison value>
A substantially intermediate value between the quotient of the total value and the count value of the bar or space for 2 modules and the count value of the bar or space for 3 modules.
<Third comparison value>
A substantially intermediate value between the quotient of the total value and the count value of the bar or space for 3 modules and the count value of the bar or space for 4 modules.
That is, these comparison values are set based on the total value that is the sum of the count values corresponding to the widths of the bars and spaces, and the count values for 1 to 4 modules.

  Then, as described above, the width of the bar or space is determined in the reading direction because the barcode is printed on the curved surface or the reading operation is performed by tilting the reader with respect to the printed surface of the barcode. If the barcode is read in a gradually changing state, the number and the total width of the bar code having a relatively small number and the total width, such as the structure of one character described in Patent Document 1, such as a bar, four spaces, and a total width of 7 modules, are described. In the system, even if the count value of each bar and space fluctuates, the effect is hardly noticeable.

However, in the case of a barcode system such as CODE128 where the number of components is 6 and the total width is 11 modules, or a system where the number of components and the total width are more than that, the sum of these individual count values is added. It is assumed that an error is likely to occur in the width value determined based on this.
The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a bar code reading apparatus and a bar code discriminating method capable of making bar code reading errors less likely to occur. .

  According to the barcode reading apparatus of the first aspect, a combination of consecutive elements that is two or more and smaller than the number of elements constituting one character is defined as a decoding subset. A plurality of subsets are set while shifting by a predetermined number of elements in one character, the sum of the width values of the elements belonging to each subset is obtained, and one character is determined based on the ratio of the total values.

  That is, since a character in a barcode is defined by an array of a plurality of elements, if a plurality of consecutive combinations of these elements are set, the character can be specified by a ratio formed by the width value of the combination. Therefore, even if the width of an element read in one character varies due to various factors, the variation can be absorbed by comparing and evaluating the width value of the subset. Reliability can be improved.

  According to the barcode reader of claim 2, two adjacent elements each have four kinds of width values, one character is composed of six elements, a subset is composed of four elements, and one element Since barcodes that are set so as to be shifted one by one are to be read, it is possible to improve the reading reliability of barcodes having the same standard as CODE128.

  According to the barcode reader of claim 3, when there are a plurality of characters corresponding to the ratio of the total value, the width values of the elements constituting the character are respectively determined, and the character is determined based on the arrangement of the elements. Is determined. In other words, depending on the barcode specification, a combination of subset width ratios may correspond to a plurality of characters. Even in such a case, if the width value of the element which each character candidate has is determined individually, the character can be reliably identified.

  According to the barcode reader of claim 4, when there are a plurality of characters corresponding to the ratio of the total value, a pair is set for every two adjacent elements constituting the character, and each pair is The sum of the width values of the elements to be formed is determined, and the character is determined based on the ratio of the total values. Even in such a system, the character can be reliably specified as in the third aspect.

  According to the barcode reading apparatus of the fifth aspect, when the barcode determination fails, the same determination processing is executed based on the arrangement order of the elements in the reverse direction, so that the first barcode reading is simply reversed. When it is performed in the direction, it is possible to avoid being processed as a read failure.

(First embodiment)
A first embodiment in the case where the present invention is applied to CODE128, which is a four-value width barcode, will be described below with reference to FIGS. FIG. 4 shows the electrical configuration of a known barcode reader 10. The reading device 10 includes, for example, a hand-held type and a stationary type, and each includes an optical reading unit and a data processing unit. As the optical reading unit, the LEDs 11 and 12 that project illumination light from a plurality of directions onto a recording surface D such as a sheet on which the barcode 1 to be read is recorded, and an image of the recording surface D is taken. A lens 13 and a CCD (Charge Coupled Device) image sensor 14 are provided.

  The entire internal control is performed by the control unit 15. The control unit 15 is provided with an internal memory, an interface, and the like mainly using a CPU, and stores a reading processing program. The above-described output terminal of the CCD image sensor 14 is connected to the memory 18 via the amplifier circuit 16 and the A / D conversion circuit 17. In addition, the output terminal of the A / D conversion circuit 17 is connected to the memory 18 via the binarization circuit 19.

An image signal photographed by the CCD image pickup device 14 is amplified in an analog manner by an amplifier circuit 16, converted into a digital signal through an A / D conversion circuit 17, and stored in a memory 18 as binarized image data. The
The CCD image pickup device 14 and the specific ratio detection circuit 19 are supplied with a synchronization signal from a synchronization signal generation circuit 20. The synchronization signal generation circuit 20 provides a synchronization signal also to the address generation circuit 21, and provides an address signal to the memory 18. The LEDs 11 and 12, the amplifier circuit 16, the A / D conversion circuit 17, the specific ratio detection circuit 19, the memory 18, and the synchronization signal generation circuit 20 are configured to receive a control signal from the control unit 15 and to exchange information. Yes.
The reading device 10 is provided with an operation switch 22 for performing various operation inputs, and the control unit 15 receives inputs. Further, the control unit 15 is provided with an LED 23, a buzzer 24, a liquid crystal display 25, and the like for displaying a control state and performing a notification operation. Further, a communication interface 26 for communicating with an external device is connected.

FIG. 1 shows an example of a pattern of CODE 128, which indicates “start C”, “12”, “14 (check code: CHK)”, and “stop” with four characters. Bars and spaces, each of which is an element, are alternately arranged adjacent to each other. The element pattern of each character (B is a bar and S is a space) is defined as follows. The numerical value of the element pattern is a bar or space width value.
Character BSBSBSB
Start C 21232
12 112232
14 122231
Stop 2331112
Here, regarding the first to sixth elements constituting the character “start C”, a group including the four elements (1, 2, 3, 4) from the top is defined as a decoding subset a. Then, a group including four elements (2, 3, 4, 5) obtained by shifting subset a by one element is defined as subset b, and further, four elements (3,4, 4) obtained by shifting subset b by one element are defined. A group including (5, 6) is defined as a subset c. Then, the sum of the width values of the elements included in each of the subsets a to c is as follows.
Subset a: 2 + 1 + 1 + 2 = 6
Subset b: 1 + 1 + 2 + 3 = 7
Subset c: 1 + 2 + 3 + 2 = 8
Therefore, the total ratio of the element width values constituting the subsets a, b, and c is 6: 7: 8, and the ratio is specified as either the character “start C” or the character “03”. be able to. Then, it can be identified as “start C” from the feature of the character (start character) located at the beginning of the pattern.

Similarly, regarding the other characters “12”, “14”, and “stop”, the total ratio of the element width values constituting the subsets a, b, and c is obtained as follows (FIG. 1 (b)). )reference).
Character a: b: c
12 6: 8: 9
14 7: 9: 8
Stop 9: 8: 6
As described above, the total ratio of the element width values constituting the subsets a, b, and c is obtained for all element patterns in the CODE 128, and a list is shown in FIG. However, when characters are made to correspond to such a total ratio, a maximum of four overlaps occur. Therefore, it is necessary to separately specify which character corresponds to the portion. Note that the control unit 15 of the reading device 10 stores the list of FIG. 2 as a data table in a built-in memory (not shown).

Next, the operation of this embodiment will be described with reference to FIG. FIG. 3 is a flowchart showing the control content of the barcode reading process performed mainly by the control unit 15 of the reading device 10. However, steps S1 to S6 are general reading processes. That is, the reading device 10 captures image data captured by the CCD image sensor 14 into the memory 18 via the A / D conversion circuit 17 (step S1), and detects the light level and dark level of the image data (step S1). S2) When a threshold value for binarizing image data is determined (step S3), the image data is binarized using the threshold value (step S4). Then, the image data captured in the memory 18 is converted into light (space) and dark (bar) pattern data (step S5).
When the binarization circuit 19 is used, the processing of steps S2 to S4 is executed by hardware by the binarization circuit 19, and the binarized image data is written in the memory 18 from the beginning. Become.

  Subsequently, when the light / dark pattern data is divided into character candidates for N characters (step S6), the control unit 15 initializes a counter n for counting the number of characters to “1” (step S7). Then, for the nth character (in this case, the first character), the sum of the width values of 6 elements consisting of 3 bars and 3 spaces is obtained, and the sum is divided by “11” which is the total number of elements of 1 character. Thus, the basic minimum element width “1” is determined (step S8).

  Next, the control unit 15 sets decoding subsets a, b, and c for the nth character candidate (step S9). That is, as described above, for the first to sixth elements constituting the nth character candidate, the group including the first to fourth elements is the subset a, the group including the second to fifth elements is the subset b, the third A group including the sixth element is set as a subset c. Then, the sum of the element widths of each of the subsets a, b, and c is measured based on the basic minimum element width, rounded to an integer, and the ratio of a: b: c is obtained (step S10).

  Next, the control unit 15 refers to the data table (data table 1) shown in FIG. 2 and which character candidate in the data table corresponds to the pattern of the ratio a: b: c obtained in step S10. Is determined (step S11). Here, if there is only one applicable character candidate (step S12, “NO”), the character is determined at that time, so it is determined whether or not the counter n matches the total number of characters (step S13). . In step S13, if the two do not match (“NO”), the counter n is incremented (step S14), and the process returns to step S8. If both match (“YES”), the process is terminated.

  On the other hand, in step S12, when there are a plurality of character candidates corresponding to the pattern of the ratio a: b: c obtained in step S10 (“YES”), the control unit 15 specifies a character from among these candidates. That is, the width ratio of the light and dark pattern is determined for each of the subsets a, b, and c, and it is determined which character candidate corresponds to the light and dark pattern (step S15).

For example, the character “stop” has a light / dark pattern “233111 (2)” and the width ratio of the subset a: b: c is 9: 8: 6. Referring to FIG. Corresponds to the character “41”. That is, since the light and dark pattern of the character “41” is “231313”,
Subset a: 2 + 3 + 1 + 3 = 9
Subset b: 3 + 1 + 3 + 1 = 8
Subset c: 1 + 3 + 1 + 1 = 6
It has become.

In this case, if the light and dark patterns of subset a are compared,
"Stop": 2311
“41”: 2313
Therefore, either one can be specified. Accordingly, the control unit 15 refers to the CODE 128 code table (data table 2), and identifies the character corresponding to the light / dark pattern among the nth character candidates (step S16). In the case of “stop” and “41”, the identification can be made by comparing only the pattern of the subset a. However, in the case of a combination in which the pattern is the same and cannot be distinguished, the comparison is similarly performed for the subsets b and c. Is identified. Then, the process returns to step S13. Further, the control unit 15 only needs to hold the code table data of the CODE 128 only for the table shown in FIG.

  As described above, according to the present embodiment, the reading apparatus 10 sets three decoding subsets each consisting of four consecutive elements in one character of the CODE 128 that is the barcode 1 while shifting by one element number. The sum of the width values of the elements belonging to each of the subsets a, b, and c is obtained, and one character is discriminated based on the ratio of the total values.

Therefore, even when the width of an element read in one character varies due to various factors, the variation can be absorbed by comparing and evaluating the width values of the subsets. In addition, since the determination is performed by rounding the respective width ratios to the integer values for the three subsets in one character, the possibility of rounding errors is further reduced. Therefore, it is possible to improve reading reliability as compared with the prior art.
Further, when there are a plurality of characters corresponding to the width ratio of the subset, the reader 10 determines the width value of each element constituting the character and determines the character based on the arrangement of those elements. Can be reliably identified.

(Second embodiment)
FIG. 5 shows a second embodiment of the present invention. The same parts as those in the first embodiment are denoted by the same reference numerals and the description thereof is omitted. Only different parts will be described below. In the second embodiment, the process of step S15 of the flowchart shown in FIG. 3 in the first embodiment is executed by a different method.

  That is, as shown in FIG. 5, a pair is set for every two adjacent elements (bar, space) among the elements constituting one character of the barcode 1. Then, the sum of the width values of each pair of elements is obtained. In the case of the character “start C”, 3 (2 + 1): 3 (1 + 2): 5 (3 + 2). On the other hand, the character “41” is 5 (2 + 3): 4 (1 + 3): 2 (1 + 1). Therefore, if the character candidate width ratio matches with which ratio, the corresponding character can be specified.

  As described above, according to the second embodiment, when there are a plurality of characters corresponding to the width ratio of the subset, the control unit 15 of the control device 10 applies to every two adjacent elements constituting the character. A pair is set, the sum of the width values of the elements forming each pair is obtained, and the character is determined based on the ratio of the total values. Therefore, the character can be reliably specified as in the first embodiment.

(Third embodiment)
FIG. 6 shows a third embodiment of the present invention, and only parts different from the first embodiment will be described. The third embodiment shows a process when the barcode 1 cannot be read normally. FIG. 6 corresponds to a part of the flowchart of FIG. If it is determined as “NO” as a result of executing Step S12, the control unit 15 determines whether there is no character candidate (Step S20). If there is one character candidate corresponding to the character candidate, it is also determined as “NO” here, and after performing a process of resetting a backward flag described later (step S21), the process proceeds to step S13.

In step S20, when there is no character candidate (“YES”), the control unit 15 determines whether or not the reverse direction flag is set (step S22). If not set (“NO”), instead of the process of step S9, a subset for decoding is set in the reverse direction (step S23).
For example, the pattern of the character “stop” is “2331112”, and when the reading device 10 reads the pattern in the reverse direction, the subset is set as follows in step S9.
Subset a: 2 + 1 + 1 + 1 = 5
Subset b: 1 + 1 + 1 + 3 = 6
Subset c: 1 + 1 + 3 + 3 = 8
Then, the subset width ratio 5: 6: 8 in this case corresponds to the character “65”, but it is obviously abnormal that the first character is not “Start A to C”. In such a case, it is assumed that the barcode 1 is read from the opposite direction. Therefore, the control unit 15 sets the subset in the reverse direction for the read light / dark pattern, sets the reverse flag in the flag storage area of the work area (step S24), and proceeds to step S10.

  If the barcode 1 is simply read from the reverse direction, “YES” is determined in step S12 or “NO” in step S20 next time. On the other hand, if there is no corresponding character candidate at the next time and it is determined again ("YES") in step S20, the reverse flag is set this time, so that "YES" is also determined in step S22. . In this case, since it is assumed that the read barcode is not the original barcode 1 to be read, an error notification process for notifying that is performed (step S25), and the process ends.

  As described above, according to the third embodiment, when the control unit 15 of the reading device 10 fails to determine the barcode 1, it executes the same determination process based on the arrangement order of the elements in the reverse direction. If the first barcode 1 is simply read in the reverse direction, it can be avoided that it is processed as a read failure.

The present invention is not limited to the embodiments described above and shown in the drawings, and the following modifications or expansions are possible.
The bar code is not limited to CODE 128, but can be applied to any bar code in which two adjacent elements each have three or more width values and one character is composed of six or more elements.
When the subset width ratios and the characters all correspond one-to-one, the processes in steps S12, S15, and S16 are unnecessary.
When setting a subset, the elements may be shifted by 2 or more depending on the total number of elements constituting one character.

The first embodiment when the present invention is applied to CODE128, and shows a pattern example of CODE128 and a setting example of a decoding subset. Data table showing correspondence between width ratio of subsets and character candidates Flowchart showing control contents of barcode reading process performed mainly by control unit of reading apparatus The figure which shows the electric constitution of a barcode reader FIG. 1 equivalent view showing a second embodiment of the present invention. FIG. 3 is a partial equivalent diagram of FIG. 3 showing a third embodiment of the present invention. The figure which shows an example of the barcode of CODE128

Explanation of symbols

  In the drawings, 1 is a bar code and 10 is a reader.

Claims (10)

A bar code reader for reading a bar code in which two adjacent elements each have three or more width values, and one character is composed of six or more elements,
A consecutive combination of two or more elements less than the number of elements constituting one character is defined as a subset for decoding.
In one character, a plurality of the subsets are set while being shifted by a predetermined number of elements,
Find the sum of the width values of the elements belonging to each subset,
The bar code reader according to claim 1, wherein the character is discriminated based on the ratio of the total values. The barcode is
Two adjacent elements each have four different width values,
1 character consists of 6 elements,
2. The barcode reading apparatus according to claim 1, wherein the subset is composed of four elements, and the subset is set to be shifted by one element.   2. The method according to claim 1, wherein when there are a plurality of characters corresponding to the ratio of the total value, the width values of the elements constituting the character are respectively determined, and the character is determined based on the arrangement of the elements. Or the barcode reader of 2.   When there are a plurality of characters corresponding to the ratio of the total value, a pair is set for every two adjacent elements constituting the character, and the sum of the width values of the elements forming each pair is obtained. 3. The bar code reader according to claim 1, wherein the character is discriminated based on a ratio of the total value.   5. The bar code reader according to claim 1, wherein when the bar code discrimination fails, the same discrimination process is executed based on the arrangement order of the elements in the reverse direction. A barcode discriminating method for reading a barcode in which two adjacent elements each have three or more width values, and one character is composed of six or more elements,
A consecutive combination of two or more elements less than the number of elements constituting one character is defined as a subset for decoding.
In one character, a plurality of the subsets are set while being shifted by a predetermined number of elements,
Find the sum of the width values of the elements belonging to each subset,
A bar code discrimination method comprising: discriminating the one character based on the ratio of the total values. The barcode is
Two adjacent elements each have four different width values,
1 character consists of 6 elements,
7. The barcode discriminating method according to claim 6, wherein the subset is composed of four elements and is set so as to be shifted by one element.   7. When there are a plurality of characters corresponding to the ratio of the total value, the width values of the elements constituting the character are respectively determined, and the character is determined based on the arrangement of the elements. Or the barcode discrimination | determination method of 7.   When there are a plurality of characters corresponding to the ratio of the total value, a pair is set for every two adjacent elements constituting the character, and the sum of the width values of the elements forming each pair is obtained. 8. The bar code discrimination method according to claim 6, wherein the character is discriminated based on a ratio of the total value. 10. The barcode determination method according to claim 6, wherein when the determination of the barcode is unsuccessful, the same determination processing is executed based on the arrangement order of the elements in the reverse direction.

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