JP2008159084A - Bar code reading method, bar code reader and computer program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a bar code reading method for surely discriminating each of bar codes having multiple kinds of similar patterns. <P>SOLUTION: When decoding of RSS_Limited is normally completed ("Yes" in step A15), a control circuit of a bar code reader determines whether a character code of UPC-A/EAN-13 exists at least at one of both ends of a code pattern of RSS_Limited (step A18). If the character code does not exist ("NO"), a read code pattern is determined as RSS_Limited, and if the character code exists ("Yes"), read "NG" is determined (step A14). <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention provides a barcode reading method, a barcode reading apparatus, and the apparatus for optically reading a barcode created based on a plurality of types of standards and decoding data recorded in the barcode. The present invention relates to a program executed by a computer that controls the computer.

In recent years, many types of barcodes have been developed and actually used. For this reason, there is a case where a part of a predetermined barcode constitutes another type of barcode. Therefore, when the reader is configured to support reading of a plurality of types of barcodes, there is a possibility that reading errors may occur if the types of barcodes cannot be clearly distinguished even in such a situation. is there.
For example, Patent Document 1 discloses a configuration example of a device that can read a plurality of types of barcodes.
JP-A-6-295352

  However, the technique disclosed in Patent Document 1 has been made for the purpose of shortening the time required for the reading process by executing the process commonly performed for reading a plurality of types of barcodes at the beginning. It is. Therefore, as described above, it does not contribute to the solution of the technical problem of how to determine each of the barcodes having similar patterns.

  SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a barcode reading method and a barcode capable of more reliably discriminating each of a plurality of types of similar pattern barcodes. A code reader and a computer program are provided.

  According to the bar code reading method according to claim 1, the light and dark pattern sequence obtained by binarizing the read bar code is read by applying the reading algorithm of the second standard, and the reading ends normally. Even in this case, if there is a character pattern, start or stop pattern of the first barcode on at least one of both ends of the light / dark pattern row, it is determined that reading has failed. That is, if the first barcode pattern exists at at least one end of the read barcode, the light / dark pattern may be the first barcode. Therefore, it is possible to prevent a reading error by determining that reading has failed in that case.

  According to the bar code reading method of claim 2, the light and dark pattern sequence obtained by binarizing the read bar code is read by applying the reading algorithm of the second standard, and the reading ends normally. Even in this case, if there is a character pattern of the first barcode at at least one of both ends of the light / dark pattern row, it is determined that reading has failed. That is, if the barcode read at the very end of the reading field is the second barcode with no margin set, there may be a bar that could not actually be read outside the barcode. Therefore, it is possible to prevent a reading error by determining that reading has failed in that case.

  According to the barcode reader of claim 4, when the barcode reading method according to claim 1 or 2 is configured to be executable, whether or not a margin is appropriately set for each barcode. Is configured to be settable for each bar code type. Therefore, for example, when only a bar code with no margin is read, reading can be performed quickly without performing unnecessary determination processing.

(First embodiment)
Hereinafter, a first embodiment of the present invention will be described with reference to FIGS. FIG. 3 schematically shows the electrical configuration of the barcode reader. This bar code reader 1 is for optically reading a bar code printed on a reading object A, and includes a power supply circuit 2, a control circuit (computer) 3, a memory 4, an operation unit 5, an illumination drive circuit 6, An irradiation unit 7, an imaging unit 8, a sensor driving circuit 9, an optical sensor 10, a clock control circuit 11, a waveform shaping unit 12 and an external interface unit 13 are provided.
The power supply circuit 2 is configured by, for example, an AC / DC converter, and converts AC power supplied from the outside into DC and supplies DC power to all components of the reader 1. The power supply circuit 2 may be provided as necessary. For example, in the case of a hand-held bar code reader, the power supply circuit 2 may be driven using a built-in battery.

  The control circuit 3 is constituted by a microcomputer, for example, and controls the entire reading device 1 based on a control program, which will be described in detail later. The operation unit 5 includes various operation setting keys such as a trigger key and a numeric key. For example, when the trigger key is operated by a user or the like, the reading device 1 is controlled based on the control of the control circuit 3. Start processing operation. The illumination drive circuit 6 gives a drive signal to the irradiation unit 7 based on the control of the control circuit 3. The memory 4 stores a control program (computer program) 14 for the control circuit 3. The irradiation unit 7 is configured by, for example, an LED or the like, and irradiates the reading object A with light when a driving signal is given from the illumination driving circuit 6.

  The image forming means 8 is constituted by, for example, a lens, and forms an image of the light irradiated and reflected on the reading object A from the irradiation unit 7 and gives it to the optical sensor 10. The optical sensor 10 is also referred to as, for example, an area sensor. For example, light receiving elements such as a CCD are arranged in a two-dimensional plane, and a corresponding light receiving element and its range (capture target area) are set to set all pixel signals The reflected light reflected on the reading object A is photoelectrically converted. The exposure time for exposure by the optical sensor 10 is configured to be set by the control circuit 3.

  When the control circuit 3 drives and controls the optical sensor 10 via the sensor drive circuit 9, the optical sensor 10 gives a signal obtained by photoelectric conversion based on the capture mode to the waveform shaping unit 12. The sensor drive circuit 9 gives the optical sensor 10 a clock for outputting a pixel signal from the light receiving element of the optical sensor 10. The waveform shaping unit 12 amplifies the signal photoelectrically converted by the optical sensor 10 and gives a signal of a luminance level to the control circuit 3. The amplification factor of the waveform shaping unit 12 is configured to be set by the control circuit 3. The external interface unit 13 enables data input / output between the control circuit 3 and an external device (not shown).

  Next, the operation of the present embodiment will be described with reference to FIGS. FIG. 1 is a flowchart showing the processing contents when the control circuit 3 executes the control program 14, and shows only the part related to the gist of the present invention. Note that the processing from steps A1 to A14 is not different from that of a barcode reader having a general configuration.

  First, the control circuit 3 sets the minimum bar number X that can be read from a plurality of types of bar codes designated as reading targets by the user (step A1). After that, the barcode luminance level signal optically read by the optical sensor 10 and given through the waveform shaping unit 12 is binarized, that is, converted into a light / dark pattern, and then the code area is cut out. Subsequently, the number n of bars and the bars are detected from the light / dark pattern (steps A2 and A3).

  Next, the control circuit 3 compares the number of bars n with the minimum number of bars X, and if n ≧ X (step A4, “YES”), determines the barcode to be decoded according to the number of bars n. (Step A5). Then, a margin check is performed according to the type of the barcode between the first white bar (usually corresponding to the margin area) of the light / dark pattern and the black bar positioned next (inside) or from the first character pattern. (Step A6). If the number of bars n is less than the minimum number of bars X in step A4 (“NO”), reading is unsuccessful at that time, and “NG” is determined (step A14).

  In step A6, if there is a specified margin (“OK”), decoding is performed by applying a reading algorithm corresponding to the type of barcode to the light and dark pattern sequence (step A7, first process). On the other hand, if the specified margin does not exist (“NG”), the bars at both ends of the pattern row are reduced by one (n = n−2, step A10) and the process returns to step A4, and the minimum number of bars X is again set. Make a comparison. If the decoding result in step A7 is “OK” without any problem (step A8, “YES”), a margin check is performed with reference to the black bar or character pattern at the end of the pattern row (step A9).

  If the decoding in step A7 fails and “NG” (step A8, “NO”), the number m of bars evaluated as decoding targets in step A7 is subtracted from the number n of bars (n = n−m, step A11), returning to step A4, the comparison with the minimum number of bars X is performed again. If the margin check in step A9 is “OK”, the reading is successful “OK” (step A13), and if the margin check is “NG”, the process proceeds to step A11.

  The processing content in the following steps A15 to A17 is a characteristic part of the present invention. That is, when the reading once becomes “OK” in step A13, the control circuit 3 determines whether or not the barcode is RSS_Limited (second barcode) (step A15, second process), and RSS_Limited. Otherwise ("NO"), the process is terminated as it is. On the other hand, when the barcode is RSS_Limited (“YES”), the module which is the minimum unit width of the bar is detected from the decoding result in step A7 (step A16). Then, it is determined whether or not there is a white bar of 5 modules or more on at least one of the both ends outside the barcode pattern (step A17).

  Reference is now made to FIG. Fig. 2 shows an example of the RSS_Limited barcode pattern and an example of the UPC-A barcode pattern, which is a kind of POS code. The former pattern matches the part of the latter pattern vertically. As shown. RSS_Limited is a specification in which the code size is smaller than that of UPC-A (that is, the number of bars is smaller) and provision of a margin is not specified. Therefore, when trying to read the UPC-A / EAN-13 pattern, there is a possibility that it is erroneously read as RSS_Limited depending on the reading state.

  Therefore, in step A17, when at least one of the barcodes has a margin of 5 modules or more, the reading result as RSS_Limited is set to “OK”. That is, since the bars constituting the UPC-A / EAN-13 are 1 to 4 modules, the bars having a width of 5 modules or more do not constitute a part of the UPC-A / EAN-13. Therefore, if the white bar exists in at least one of RSS_Limited, it can be determined that there is no problem in reading the barcode as RSS_Limited.

  On the other hand, if there is a 1-4 module width bar in step A17 ("NO"), the decoded code pattern may be part of UPC-A / EAN-13. Accordingly, in this case, the process proceeds to step A14 and the reading is processed as “NG”.

  As described above, according to this embodiment, the control circuit 3 of the barcode reader 1 exists when it is assumed that the code pattern is a part of the POS code when the decoding of RSS_Limited is normally completed. It is determined whether or not there is a white bar of 5 modules or more on at least one of both ends of the light / dark pattern row with respect to the maximum bar width (4 modules). If the white bar exists, the read bar code is determined as RSS_Limited, so that misreading with a POS code whose code pattern actually partially matches can be prevented.

(Second embodiment)
4 and 5 show a second embodiment of the present invention. The same parts as those of the first embodiment are denoted by the same reference numerals and the description thereof is omitted. Only different parts will be described below. The configuration of the bar code reader 1 is basically the same as that of the first embodiment, and the software reading process by the control circuit 3 is different.

  FIG. 4 is a diagram corresponding to FIG. 1, but if the control circuit 3 determines “YES” in step A15, the character code of UPC-A / EAN-13 exists at at least one of both ends of the code pattern of RSS_Limited. (Step A18). If the character code does not exist (“NO”), the read code pattern is confirmed as RSS_Limited, and the process is terminated as it is. However, if the character code exists (“YES”), the reading is set to “NG”. (Step A14).

  That is, as shown in FIG. 5, although the original barcode is UPC-A / EAN-13, the entire barcode does not fit in the reading field of the reading device 1, and a result of reading a part of the code pattern. May match the RSS_Limited code pattern. In such a case, if there is a UPC-A / EAN-13 character code on at least one end of the read code pattern, the code pattern may be UPC-A / EAN-13. Can be estimated. Therefore, reading error can be prevented by setting the reading to “NG” in that case.

(Third embodiment)
6 and 7 show a third embodiment of the present invention, and only the parts different from the second embodiment will be described. In the third embodiment, the control circuit 3 determines whether or not a predetermined distance exists between both ends of the read code pattern and both ends of the reading field in step A19 instead of step A17. If the predetermined distance exists ("YES"), the read code pattern is confirmed as RSS_Limited, and the process is terminated as it is. If there is no predetermined distance ("NO"), the reading is set to "NG" ( Step A14).

  That is, as shown in FIG. 7, the code pattern of UPC-A / EAN-13 is originally the same as in the third embodiment, but the entire code pattern does not fit in the reading field of the reading apparatus 1, and can be read with the margin of the field of view. May match the code pattern of RSS_Limited. Therefore, reading error “NG” in this case can prevent UPC-A / EAN-13 reading errors.

  In addition, unlike the state of FIG. 7, it is assumed that the barcode is actually RSS_Limited, but the illumination intensity of the illumination unit 7 tends to be low at both ends of the field of view, and accurate binarization is possible. It is also assumed that this is not possible. Accordingly, it is possible to prevent reading errors by determining that reading has failed in such a case.

(Fourth embodiment)
8 to 11 show a fourth embodiment of the present invention. The fourth embodiment relates to processing when the control circuit 3 of the barcode reader 1 performs a barcode margin check. The margin check in the fourth embodiment is performed, for example, in step A6 or step A9 in the first embodiment. First, the current problem when performing a margin check on a read barcode will be described with reference to FIGS.

  When the barcode is read by the two-dimensional sensor, as described above, the area where the barcode is located is extracted from the entire read image, one scanning line is drawn with respect to the area, and along the scanning line. Read. On this scanning line, for example, as shown in FIG. 10, when the black bar is saturated and whitened due to specular reflection, or when the black bar is rubbed or voids due to poor printing of the label, the portion is regarded as a margin. It may be mistaken for an area and processed. In that case, the bar code is lost or misread.

  In addition, reading is possible at all angles of 360 degrees, and when the barcode is read in a two-dimensionally inclined state, the scanning line may come off the barcode halfway as shown in FIG. is there. In order to prevent such a situation, the direction in which the black bar that first hits the scanning line extends is traced, the angle formed by the black bar with respect to the horizontal of the reading reference is obtained, and the perpendicular to the black bar is set. Calculation is performed, and scanning is redrawn along the perpendicular to perform reading.

  However, when a barcode is read by a two-dimensional sensor, if the reading is performed with an elevation angle and a depression angle with respect to the plane on which the barcode is printed, the barcode image becomes trapezoidal as shown in FIG. It may be distorted. As described above, when the image is distorted, even if the scanning line is redrawn along the perpendicular line to the first black bar hit as described above, the scanning line may come off the barcode from the middle. .

  Therefore, in the fourth embodiment, a margin check is performed according to the flowchart shown in FIG. First, the control circuit 3 sets a scanning line (step B0). Then, the black bars located at both ends of the read barcode are traced (step B1), and it is determined whether or not the two black bars are parallel (step B2). If both are parallel (“YES”), it is possible to perform a margin check along the scanning line without any problem as usual (step B3). If there is a margin corresponding to the type of barcode (step B4, “YES”), the process ends.

  On the other hand, if the barcodes at both ends are not parallel in step B2 ("NO"), the barcode outline ABCD is obtained along the scanning line (see step B6, Fig. 9B). Next, the margin amount defined according to the type of barcode is calculated from the outer shape ABCD, and margin areas ABA'B 'and CDC'D' are obtained and set on both sides of the outer shape ABCD (step B7).

  Subsequently, as shown in FIG. 9C, a plurality of inspection lines are set outward from both ends of the outer shape ABCD for the margin areas ABA'B 'and CDC'D' (step B8). It is determined whether or not a margin defined for each inspection line is secured (step B9). For example, if three or more inspection lines are set and a large number of inspection lines are secured, it is determined as “OK” (“YES”), and the process is terminated. If there are a small number of margins ("NO"), the reading is "NG" (step B5).

  As described above, according to the fourth embodiment, when the barcode is read two-dimensionally by the optical sensor 10 which is an area sensor, a plurality of barcode patterns are provided at different positions in the bar height direction at least at one end of the barcode pattern. The inspection lines are set, and it is determined whether a margin is secured for each of the inspection lines. Accordingly, when the reading by the reading device 1 is performed in a state where it is inclined so as to have an elevation angle or depression angle with respect to the plane on which the barcode is printed, the barcode image is inclined at both ends. Even if the print quality of the bar code is not good, it can be reliably determined whether or not there is a margin.

  Further, since three or more inspection lines are set and whether a margin is secured for these inspection lines is determined based on the majority rule, it is possible to appropriately determine whether or not there is a margin. Then, it is determined whether the arrangement of the bars located at both ends is parallel. If both are not parallel, a plurality of inspection lines are set. If both are parallel, a margin check is performed as in the conventional case. I did it. Therefore, the reading can be performed more quickly by setting a plurality of inspection lines only when it is estimated that the reading of the barcode is performed in a tilted state.

(5th Example)
12 and 13 show a fifth embodiment of the present invention. For example, when a barcode is attached to a place where space such as a table is limited, the barcode may be printed on the border of the label 15 without securing a specified margin (FIG. 13). reference). In the fifth embodiment, a margin check is reliably performed in response to such a case.

  In FIG. 12, the control circuit 3 sets an inspection line in a defined margin area outside the both ends of the bar code, and determines whether or not a black bar exists (step C1). That is, in the state shown in FIG. 13, the frame line itself of the label 15 may be detected as a black bar. If there is no black bar (“NO”), there is no problem as before, so the process proceeds to step C5 to determine whether there is a defined margin. If there is no margin defined in step C5 (“NO”), read “NG” (step C6).

  On the other hand, if there is a black bar in the margin area (“YES”), the black bar is traced to detect the height H2 (step C2). Then, the detected height H2 is compared with the bar height H1 of the bar code already read (step C3). If “H1 <H2” (“YES”), it can be estimated that the black bar detected in step C1 is not a bar constituting the barcode pattern but a frame line of the label 15. Accordingly, the black bar detected in step C1 is ignored, and the part where the black bar is located is determined to be a part of the margin area (step C4), and the process proceeds to step C5. In Step C3, if “H1 ≧ H2” (“NO”), the black bar detected in Step C1 may be a bar constituting a barcode pattern, so that the black bar is added to the code pattern. Then, decoding is performed again (step C7).

  As described above, according to the fifth embodiment, the height H2 of the bar detected on the inspection line is measured outside the both ends of the barcode pattern, and the height of the bar is read. In contrast, if the heights of the two are different, the bar detected on the inspection line is determined as a margin. Therefore, even when the barcode is printed in a state where the margin specified in the frame of the label 15 is not secured, the bar which is a part of the barcode and the frame line of the label 15 are reliably discriminated. can do.

(Sixth embodiment)
FIG. 14 shows a sixth embodiment of the present invention, and the differences from the first embodiment will be described. In the sixth embodiment, as shown in FIG. 2 of the first embodiment, all of the RSS_Limited code patterns that match a part of the UPC-A / EAN-13 code pattern are stored in the memory 4 in advance. Remember. If the determination result in step A15 is “YES”, the control circuit 3 searches for the RSS_Limited code pattern stored in the memory 4 (step A20). Then, it is determined whether or not the RSS_Limited code pattern decoded in step A7 matches the pattern stored in the memory 4 (step A21).

If there is no matching pattern in step A21 ("NO"), it is determined that the decoded RSS_Limited is not a part of the UPC-A / EAN-13 code pattern at that time, and the process is terminated. On the other hand, if there is a matching pattern ("YES"), the process proceeds to step A16 and the same processing as in the first embodiment is performed.
As described above, according to the sixth embodiment, since RSS_Limited matches a part of the UPC-A / EAN-13 code pattern, only when there is a possibility of misreading both, the same as in the first embodiment. Since processing is performed, reading can be performed more efficiently.

(Seventh embodiment)
FIG. 15 shows a seventh embodiment of the present invention, and different portions from the first embodiment will be described. In the seventh embodiment, after executing Step A13, the control circuit 3 determines whether or not both RSS_Limited and at least one POS code are set as reading targets by the user (Step A22). If both are set as reading targets (“YES”), the process proceeds to step A15. If both are not set as reading targets (“NO”, in this case, only one of them is the target) The process is terminated as is.
That is, when both are not set as reading targets, it is premised that only one of the barcodes to be read is read, so there is no possibility that the POS code is erroneously read as RSS_Limited. Accordingly, the reading efficiency can be improved by executing steps A15 to A17 only when both are set as reading targets.

The present invention is not limited to the embodiments described above or shown in the drawings, and the following modifications are possible.
The barcode reading performed in the first to third embodiments may be performed one-dimensionally by a line sensor.
The determination of the maximum width of the bars constituting the first barcode may be performed when the bar width is detected in step A3. In addition, it is not always necessary to make a determination based on the actually read pattern. The maximum bar width is stored in advance as data according to the type of barcode assumed to be read, and is determined based on the data. May be.
In the second embodiment, instead of whether or not the UPC-A / EAN-13 character code exists, the reading is “NG” when both ends of the barcode are composed of 1 to 4 module bars. It is also good.

Also, in the second embodiment, step A15 is deleted, and whether or not the character code of the first barcode is present is determined in step A18 regardless of whether or not the barcode that is “read OK” is RSS_Limited. May be. At this time, in step A18, not only the character code of the first barcode but also whether or not a start pattern or a stop pattern exists may be determined.
In the fourth embodiment, the presence of the margin may be determined only when the margin is secured for all of the plurality of inspection lines, and in this case, the presence or absence of the margin can be more reliably determined.
In the fourth embodiment, step B2 may be omitted, and the subsequent processing may be performed regardless of whether or not the bars at both ends are parallel.
The margin check method of the fourth or fifth embodiment may be applied to step A17 of the first embodiment, for example.

The bar exceeding the maximum width in the second process may be a black bar.
The barcode reader 1 may be configured such that a means for determining whether or not a margin is appropriately set for each barcode can be set for each barcode type. With this configuration, for example, when only a barcode with no margin defined such as RSS_Limited is read, reading can be quickly performed without performing unnecessary determination processing.
The first and second barcodes are not limited to the POS code and RSS_Limited, respectively. In short, a relationship in which part of the code pattern of the first barcode matches or resembles the code pattern of the second barcode. It can be applied to what is in

The flowchart which shows 1st Example of this invention, and shows the processing content when the control circuit of a barcode reader executes a control program The figure which arranges what RSS_Limited and the part of the barcode pattern of UPC-A agree, arranged vertically Functional block diagram schematically showing the electrical configuration of the barcode reader FIG. 1 equivalent view showing a second embodiment of the present invention. The figure which shows an example of the positional relationship of the barcode of reading object, and the reading visual field of a barcode reader. FIG. 1 equivalent view showing a third embodiment of the present invention. Figure equivalent to FIG. The flowchart which shows the content of a process when it is a 4th Example of this invention and a control circuit performs a margin check. The figure explaining the processing content of FIG. 8 according to the read barcode pattern The figure which shows the setting state of the conventional scanning line (the 1) The figure which shows the setting state of the conventional scanning line (the 2) FIG. 1 equivalent view showing a fifth embodiment of the present invention. A figure showing a state where a barcode is printed on a label frame without securing a specified margin FIG. 1 equivalent view showing a sixth embodiment of the present invention. FIG. 1 equivalent view showing a seventh embodiment of the present invention

Explanation of symbols

  In the drawings, 1 is a bar code reader, 3 is a control circuit (computer), 4 is a memory, 10 is an optical sensor (area sensor), and 14 is a control program (computer program).

Claims (6)

In a barcode reading method for optically reading a barcode created based on multiple types of standards and decoding the data recorded in the barcode,
Among the plurality of types, a part of the code pattern of the first barcode based on the first standard is read as a second barcode based on the second standard in which the number of bars is set to be smaller than that of the first standard. If there is a possibility that
A first step of reading the light and dark pattern sequence obtained by binarizing the read barcode by applying the reading algorithm of the second standard;
When the reading is normally completed, it comprises a second step of determining whether or not the character pattern of the first barcode, start or stop pattern exists at at least one of both ends of the light and dark pattern sequence,
The bar code reading method according to claim 1, wherein if it is determined in the second step that the pattern of the first bar code exists, it is determined that reading has failed. In a barcode reading method for optically reading a barcode created based on multiple types of standards and decoding the data recorded in the barcode,
Among the plurality of types, a part of the code pattern of the first bar code based on the first standard is set so that the number of bars is smaller than that of the first standard, and no margin is set at both ends. When there is a possibility of being read as a second barcode based on the standard,
The light and dark pattern sequence obtained by binarizing the read barcode is read by applying the reading algorithm of the second standard,
The barcode reading method according to claim 1, wherein when the reading is normally completed, if the character pattern of the first barcode exists at at least one of both ends of the light and dark pattern row, it is determined that the reading has failed.   A bar code reading apparatus configured to execute the bar code reading method according to claim 1.   4. The bar code reader according to claim 3, wherein means for determining whether or not a margin is appropriately set for each bar code is settable for each bar code type. In a program executed by a computer that controls a barcode reader that optically reads a barcode created based on a plurality of types of standards and decodes data recorded in the barcode,
Among the plurality of types, a part of the code pattern of the first barcode based on the first standard is read as a second barcode based on the second standard in which the number of bars is set to be smaller than that of the first standard. If there is a possibility that
The light and dark pattern sequence obtained by binarizing the read barcode is subjected to a first process of reading by applying the reading algorithm of the second standard,
When the reading is normally completed, a second process for determining whether or not the first bar code character pattern, start or stop pattern exists at at least one of both ends of the light and dark pattern row, and
A computer program characterized in that, when it is determined in the second step that the first barcode pattern exists, it is determined that reading has failed. In a program executed by a computer that controls a barcode reader that optically reads a barcode created based on a plurality of types of standards and decodes data recorded in the barcode,
Among the plurality of types, a part of the code pattern of the first bar code based on the first standard is set so that the number of bars is smaller than that of the first standard, and no margin is set at both ends. When there is a possibility of being read as a second barcode based on the standard,
The light and dark pattern sequence obtained by binarizing the read barcode is read by applying the reading algorithm of the second standard,
When the reading is normally completed, if the character pattern of the first barcode exists at at least one of both ends of the light / dark pattern sequence, the computer program is determined to be reading failure.

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