JP5240161B2 - Optical information reader - Google Patents

Description

  The present invention relates to an optical information reading apparatus that reads a barcode.

  2. Description of the Related Art Conventionally, as an optical information reading device that reads a barcode, for example, a barcode reading device disclosed in Patent Document 1 below is known. The bar code reading apparatus disclosed in Patent Document 1 includes photoelectric conversion means for converting reflected light from a bar code into an electric signal, and conversion inspection for detecting white and black conversion points from the electric signal generated by the photoelectric conversion means. And a bar code is read based on a plurality of detected conversion points. Then, from the plurality of conversion points detected by the conversion point detection means, the determination means determines the truth of the conversion points that may be erroneously detected due to the influence of Fresnel diffraction along with the white and black conversion points, The determined false conversion point is corrected to a true conversion point by the correcting means.

  Patent Document 2 below describes a technique related to a barcode symbol decoding method of a barcode system in which the number of modules constituting one character is fixed. In this decoding method, first, a threshold for classifying the bar width of each bar of the barcode symbol detected by the bar width detecting means into modules is set for each character by the threshold setting means. Then, a reference value for each bar is set for each character by the reference value setting means, and each error of the bar with respect to the reference value is calculated by the error calculation means. Further, the correction value calculating means calculates the average value of the error of the bar width in the (i-1) th character calculated by the error calculating means and the correction value used in the (i-1) th character as i. The correction value is calculated as the correction value of the second character, the bars are classified into modules using the correction value, and the barcode symbol is decoded by the decoding means based on the combination.

  Patent Document 3 below describes a barcode reading apparatus that manipulates and decodes the width value so as to reduce the variation in the width value of the barcode space. In this barcode reading apparatus, first, the space width is divided into several small sections, the sections belonging to each section are searched for, and accumulated in the belonging sections to count the number of spaces in each section. Next, the value of the space width of the section in which the number of data is maximized is obtained, and all the data within the range of ± A% centering on the value of the space width is taken as one group. Then, all the data in one group is replaced with a space width value centered in this group, and decoding is performed based on the replaced data.

Japanese Patent Laid-Open No. 11-96284 JP-A-9-6885 Japanese Patent Laid-Open No. 3-206582

  By the way, for example, a barcode may be smeared or rubbed on an object due to a defective printing machine or the like. For this reason, the barcode is blurred and printed so that some bar widths are thicker than the original width value, or rubbed against the barcode so that some bar widths are thinner than the original width value. May occur and be printed. When reading a barcode with such printing unevenness, there has been a problem that the bar width changed with respect to the original width value is misread as described above, and the decoding process is likely to be defective.

  Moreover, although the said patent document 1 can correct | amend the signal detected accidentally by the influence of Fresnel diffraction among the signals of the reflected light reflected from the barcode, it is the barcode width itself of the printed barcode. It was not possible to correct fatness or thinness to the original width value.

  The above-mentioned patent document 2 can correct a barcode in which the number of modules constituting one character is fixed, but it is thick in a barcode in which the number of modules constituting one character is not fixed. There was a problem that it was not possible to correct the thinness.

  Further, in Patent Document 3, the width value of the bar code space is divided into several groups and corrected using the mode values of all the groups, but the width is far from the original width value. Even if there is a group composed of values (that is, an abnormal width value), since the mode value of the group is normal and used for correction, there is a possibility that the reading accuracy may be lowered.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide an optical information reading apparatus capable of suppressing a decrease in reading accuracy.

  In order to achieve the above object, the optical information reading apparatus according to claim 1 described in the claims is configured by arranging a plurality of dark color systems and light color systems each including one or more unit modules. An optical information reader capable of reading a barcode having a plurality of characters, a light receiving means for receiving reflected light from the barcode, and a light receiving signal output from the light receiving means A plurality of groups composed only of width value calculating means for calculating the width value, decoding means for decoding the characters based on the width values, and areas where the width values are approximated among the areas are created. And the group creation means, and among the groups created by the group creation means, the total number of the areas is regarded as the total number of areas of the same width value constituting the barcode. A group having a number equal to or greater than a normal width value group, and a first determination unit that determines a group having a total number of each region less than the predetermined number as a minority width value group; Second determination means for determining, as the abnormal width value group, a group composed of regions determined to be abnormal width values based on a difference between the width value of each region of the normal width value group, and the abnormal width value group Correction means for correcting a width value of each region constituting the image based on a difference from a width value of each region constituting at least one of the respective normal width value groups, and the decoding means Is characterized in that, when decoding of the character based on the width value of each area calculated by the width value calculation means fails, re-decoding is performed using the correction width value corrected by the correction means. .

  According to a second aspect of the present invention, in the optical information reading apparatus according to the first aspect, the correction means determines the width value of each region constituting the abnormal width value group as at least one of the normal width value groups. Correction is performed based on a difference from an average width value of each of the regions constituting one of them.

  According to a third aspect of the present invention, in the optical information reading device according to the first or second aspect, the correction means determines the width value of each region constituting the abnormal width value group by a difference from the width value. A normal width value group composed of regions having a small average width value, and a first normal width value group that is a normal width value group having an average width value smaller than the width value and an average width value larger than the width value When there is a second normal width value group that is a normal width value group, and the average width values of the first normal width value group and the second normal width value group are the first average width value and the second average width value. When the difference from the first average width value is smaller than the difference from the second average width value, the correction is made to be equal to the first average width value, and the difference from the first average width value is larger than the difference from the first average width value. When the difference from the second average width value is small, the correction is made to be equal to the second average width value. That.

  According to a fourth aspect of the present invention, in the optical information reading apparatus according to the third aspect, the correction means sets the width value of each region constituting the abnormal width value group to the first value with respect to the width value. When only one of the normal width value group and the second normal width value group exists, the average width value of the one normal width value group that exists and the other normal value in which the difference between the average width value is small Correction is performed based on the average width value of the width value group.

  According to a fifth aspect of the present invention, in the optical information reading device according to the third aspect, the correction means determines the width value of each region constituting the abnormal width value group as the first average width with respect to the width value. If the difference between the values and the difference between the second average width value and the width value are approximate, the specified width value of the character including the width value area and the width values of the other areas included in the character It corrects based on this.

  According to the first aspect of the present invention, if decoding fails, a plurality of groups composed only of regions where the calculated width values are approximated are created by the group creating means. Further, among the groups created by the group creation unit by the first determination unit, a group having a predetermined number or more in which the total number of each region is regarded as the total number of the same width value regions constituting the barcode is a normal width value group And a group in which the total number of each region is less than a predetermined number is determined as a minority width value group. Further, among the minority width value groups, a group composed of areas determined to be abnormal width values based on a difference from the width value of each area of each normal width value group by the second determination unit is an abnormal width. Judged as a value group. Then, the width value of each area constituting the abnormal width value group is corrected by the correcting means based on the difference from the width value of each area constituting at least one of the respective normal width value groups. Re-decoding is performed by the decoding means using the corrected width value.

As a result, when decoding of a barcode including an area in which the original width value has changed due to uneven printing (hereinafter referred to as an abnormal area) fails, the abnormal area has an area with a width value that approximates the width value. Since it is small, it is included in the abnormal width value group and corrected based on the difference from the width value of each region of the normal width value group. Thereby, the width value changed due to printing unevenness or the like is appropriately corrected to the original width value, and a decrease in reading accuracy can be suppressed.
In the present invention, the width value of the abnormal area is corrected by relatively comparing only the width values, regardless of the total number of width values of the dark color system and the light color system. Therefore, correction can be performed without depending on the number of modules, as well as barcodes in which the number of modules constituting one character is fixed (for example, EAN-13, EAN-8, UPC-A, etc.) It is possible to correct even a barcode whose number of modules is not fixed.

  In the invention of claim 2, the correcting means corrects the width value of each abnormal area constituting the abnormal width value group from the average width value of each area constituting at least one of each normal width value group. It is comprised so that it may correct | amend by. In this way, by using the average width value of each region of each normal width value group, even if there is variation in the width value of each region of each normal width value group, each abnormal region constituting the abnormal width value group The width value is appropriately corrected, and a decrease in reading accuracy can be suppressed.

  In the invention of claim 3, when the first normal width value group and the second normal width value group exist for the abnormal width value group, the width value of each abnormal region constituting the abnormal width value group is the second value. When the difference from the first average width value is smaller than the difference from the average width value, the second average width value is corrected to be equal to the first average width value. When the difference is small, the correction is made to be equal to the second average width value. Thereby, the width value of each abnormal region constituting the abnormal width value group can be appropriately corrected using the average width value of the normal width value group closest to the respective width value.

  In the invention of claim 4, when only one of the first normal width value group and the second normal width value group exists for the width value of each abnormal region constituting the abnormal width value group, The width value of the abnormal region is corrected based on the average width value of one normal width value group that exists and the average width value of another normal width value group in which the difference between the average width values is small. Thereby, for example, even if the second normal width value group does not exist and only the first normal width value group exists because the width value of each abnormal region is larger than the average width value of each normal width value group, The width value of the abnormal region can be appropriately corrected based on the average width value of the first normal width value group and the average width value of another normal width value group in which the difference between the average width values is small.

  In the invention of claim 5, when the width value of each abnormal region constituting the abnormal width value group is approximated by the difference between the first average width value with respect to the width value and the difference between the second average width values with respect to the width value Is configured to be corrected by the correcting means based on the prescribed width value of the character including the abnormal region of the width value and the width value of the other region included in the character. Thereby, since the difference between the two average width values with respect to the width value of the abnormal region is approximate, even if there is a possibility that the width value of the abnormal region can be corrected to either of the two average width values. The width value of the abnormal area is set to either the first average width value or the second average width value based on the specified width value of the character including the abnormal area and the width value of the other area included in the character. Can be corrected appropriately.

1 is a block diagram showing an electrical configuration of an optical information reading apparatus 10 according to the present embodiment. 2 is a part of a flowchart illustrating the flow of a reading process in the control circuit 40 of FIG. 1. 2 is a part of a flowchart illustrating the flow of a reading process in the control circuit 40 of FIG. 1. It is a flowchart which illustrates the subroutine of the 1st correction process in this embodiment. It is a flowchart which illustrates the subroutine of the individual correction process in this embodiment. It is a figure for demonstrating an ascending order arrangement | sequence process, a group creation process, and a normal width value correction process. It is a figure for demonstrating a 2nd correction process. It is a figure for demonstrating the 1st abnormal width value correction process in this embodiment, FIG. 8 (A) is a figure which illustrates the character before a 1st correction process, FIG.8 (B) is a 1st correction process. It is a figure which illustrates the back character. FIG. 9A is a diagram for explaining a second abnormal width value correction process in the present embodiment, FIG. 9A is a diagram illustrating a module pattern of a character, and FIG. 9B is a character before the second correction process; FIG. 9C is a diagram illustrating the character after the second correction process. It is a figure for demonstrating the 3rd abnormal width value correction process in this embodiment, FIG. 10 (A) is a figure which illustrates the module pattern of a character, FIG.10 (B) is a character before a 3rd correction process. FIG. 10C is a diagram illustrating the character after the third correction process. It is a figure for demonstrating the 4th abnormal width value correction process in this embodiment, FIG. 11 (A) is a figure which illustrates the character before a 4th correction process, FIG.11 (B) is a 4th correction process. It is a figure which illustrates the back character.

Hereinafter, an embodiment of an optical information reading device according to the present invention will be described with reference to the drawings.
As shown in FIG. 1, the optical information reading device 10 is configured as a device that reads a barcode B displayed on an object. Here, the barcode B is configured by arranging a plurality of dark color system (hereinafter also referred to as “black bar”) and light color system (hereinafter also referred to as “white bar”) areas composed of one or more unit modules. It is a code having a plurality of characters.

  The optical information reading apparatus 10 includes a circuit unit 20 housed in a case (not shown). The circuit unit 20 mainly includes an illumination light source 21, a light receiving sensor 28, an imaging lens 27, and the like. And a microcomputer (hereinafter referred to as “microcomputer”) system such as a memory 35, a control circuit 40, and a trigger switch 42.

  The optical system is divided into a light projecting optical system and a light receiving optical system. The illumination light source 21 constituting the light projecting optical system functions as an illumination light source capable of emitting the illumination light Lf, and includes, for example, a red LED and a lens provided on the emission side of the LED. In addition, in FIG. 1, the example which irradiates the illumination light Lf toward the target object R with which the barcode B was displayed is shown notionally.

  The light receiving optical system includes a light receiving sensor 28, an imaging lens 27, a reflecting mirror (not shown), and the like. The light receiving sensor 28 is configured as a CCD area sensor, and is configured to receive the reflected light Lr irradiated and reflected on the barcode B or the object R. The light receiving sensor 28 is mounted on a printed wiring board (not shown) so as to be able to receive incident light incident through the imaging lens 27. The light receiving sensor 28 corresponds to an example of a “light receiving unit” recited in the claims.

  The imaging lens 27 functions as an imaging optical system capable of condensing incident light incident from the outside via a reading port (not shown) and forming an image on the light receiving surface 28a of the light receiving sensor 28. . In the present embodiment, after the illumination light Lf emitted from the illumination light source 21 is reflected by the barcode B, the reflected light Lr is condensed by the imaging lens 27 and a code image is formed on the light receiving surface 28 a of the light receiving sensor 28. The image is formed.

  The microcomputer system includes an amplification circuit 31, an A / D conversion circuit 33, a memory 35, an address generation circuit 36, a synchronization signal generation circuit 38, a control circuit 40, a trigger switch 42, a light emitting unit 43, a buzzer 44, a vibrator 45, and a liquid crystal display. 46, a communication interface 48, and the like.

  The image signal (analog signal) output from the light receiving sensor 28 of the optical system is amplified by a predetermined gain by being input to the amplifier circuit 31, and then input from the analog signal when input to the A / D conversion circuit 33. Converted into a digital signal. When the digitized image signal, that is, image data (image information) is generated and input to the memory 35, it is stored in a predetermined code image information storage area. The synchronization signal generation circuit 38 is configured to generate a synchronization signal for the light receiving sensor 28 and the address generation circuit 36, and the address generation circuit 36 is based on the synchronization signal supplied from the synchronization signal generation circuit 38. Thus, the storage address of the image data stored in the memory 35 can be generated.

  The control circuit 40 is configured by a microcomputer that can control the entire optical information reader 10, has a CPU, a system bus, an input / output interface, and the like, has an information processing function, and has an information processing device together with the memory 35. Is configured. In the present embodiment, a trigger switch 42, a light emitting unit 43, a buzzer 44, a vibrator 45, a liquid crystal display 46, a communication interface 48, and the like are connected to the control circuit 40.

  Thereby, for example, the control circuit 40 can turn on / off the light emitting unit 43 that functions as an indicator for notifying information related to monitoring and management of the trigger switch 42 and reading of the barcode B, and a buzzer that can generate a beep sound and an alarm sound. Communication that enables ON / OFF of ringing 44, drive control of the vibrator 45 capable of generating vibration that can be transmitted to the user of the optical information reader 10, display control of the liquid crystal display 46, and serial communication with an external device Communication control of the interface 48 is enabled.

  Next, in the optical information reading apparatus 10 configured as described above, reading processing performed by the control circuit 40 when reading the barcode B will be described with reference to the flowcharts of FIGS. In the present embodiment, there are four types of bar width values in total, and a total of two black bars (dark color regions) and two white bars (light color regions) per character. A reading process for an EAN-13 barcode composed of seven modules will be mainly described as an example.

  First, an imaging process is performed in step S101 of FIG. 2, and the illumination light Lf is emitted from the illumination light source 21 toward the object R on which the barcode B is displayed in accordance with the operation of the trigger switch 42 by the operator. Then, as shown in FIG. 1, based on the light reception signal output from the light receiving sensor 28 when the reflected light Lr reflected by the object R is received by the light receiving sensor 28, the width value is determined in step S103. Arithmetic processing is performed, and the width values of the black bar and the white bar constituting each character are respectively calculated. In this width value calculation process, specifically, the respective width values are calculated by distinguishing between a black bar and a white bar according to the comparison between the signal waveform of the received light signal and a predetermined threshold value. The control circuit 40 that executes the width value calculation process in step S103 corresponds to an example of “width value calculation means” recited in the claims.

  Next, a decoding process is performed in step S105. In this process, decoding is performed based on the width values of the black bar and white bar calculated in step S103. If the decoding process is successful, it is determined Yes in step S107, and the reading process is terminated without performing the process from step S109 described later. On the other hand, if the decoding process fails in step S105, it is determined No in step S107, and the original width value is generated because printing unevenness or the like occurs in the width value calculated in the width value calculation process. The abnormal width value (that is, the width value in which the bar is thickened or thinned) is considered to be included, and the processing from step S109 is executed. The control circuit 40 that executes the decoding process in step S105 corresponds to an example of a “decoding unit” recited in the claims.

  Next, ascending order arrangement processing is performed in step S109, and the width values calculated in the width value calculation processing are arranged in ascending order regardless of the types of black bars and white bars. Specifically, for example, as shown in FIG. 6, the width values are arranged in order from a small value to a large value. Here, the vertical axis in FIG. 6 is the width value (relative value).

  Based on the graph created by this ascending order array processing, group creation processing is performed in step S111. In this group creation process, as shown in FIG. 6, the array of width values that approximate the width values is regarded as one group, and a plurality of groups (inside the one-dot chain line in FIG. 6) are created. In this embodiment, an array in which the difference between adjacent width values is within 10% is set to be regarded as one group, but this value is appropriately changed according to the type of barcode to be read. be able to. The control circuit 40 that executes the group creation processing in step S111 corresponds to an example of “group creation means” recited in the claims.

  Next, a first determination process is performed in step S113 for each group created by the group creation process. In this embodiment, since the barcode of EAN-13 is targeted for reading, the width values of the bars constituting the barcode are limited to four types. Therefore, at least a predetermined number or more of these four types of width values of the bar are provided. Will exist. Therefore, this property is used in the determination process in step S113. Specifically, in the present embodiment, among the groups created in step S111, if the total number of bars constituting each group is equal to or greater than the predetermined number, the group is determined to be a normal width value group. Is set to In addition, a group in which the total number of bars is less than the predetermined number is set to be determined as a minority width value group. Here, in the present embodiment, the predetermined number is set to 5, for example, but is not limited thereto, and can be appropriately changed according to the type of barcode to be read. The control circuit 40 that executes the determination process in step S113 corresponds to an example of a “first determination unit” recited in the claims.

  Next, in step S115, normal width value correction processing is performed. In this normal width value correction process, first, an average value of width values of each bar of each normal width value group (hereinafter also referred to as “average width value”) is calculated for each normal width value group. Here, the average width value is a value obtained by dividing a value obtained by adding the width values of the normal width value group by the total number of bars constituting the normal width value group. Then, the width value of each bar is corrected so as to be all equal to the average value calculated as described above.

  Next, in step S117, a minority width value group extraction process is performed. In this process, when there are a plurality of groups determined to be the minority width value group, a group having the smallest width value of each bar is extracted and set as the first minority width value group. When there is only one group determined as the minority value group, that group is set as the first minority value group.

Then, in step S119 of FIG. 3, the normal width value having _a smaller average width value (first average width value W _a ) than the width value of each bar of the first minority width value group extracted in step S117. Whether or not both a group (first normal width value group C ₁ ) and a large average width value (second average width value W _b ) normal width value group (second normal width value group C ₂ ) exist Determined. Here, for example, when the first few width value population is small width value population S ₁ shown in FIG. 6, the first normal width value population C ₁ and the second normal range for this small width values populations S ₁ is determined as Yes at step S119 if the value population _{C 2} exists.

Next, a second determination process is performed in step S120. In this process, based on the first and the first average width value W _a normal width values population C ₁ and the second average width value W _b of the second normal width value population C _2, the first few width value population, It is determined whether or not the width value of each bar is an abnormal width value group that is abnormal (hereinafter also referred to as “abnormal width value”). In this embodiment, an EAN-13 bar code is to be read, and the width values of the four types of bars constituting the bar code are defined at a ratio of 1: 2: 3: 4. Here, for example, from the relationship of the ratio between the first average width value W _a and the second average width value W _b , it is determined that the width value existing between both average width values is an abnormal width value that is not a specified ratio. Then, it is determined as Yes in step S120, assuming that the first minority width value group is an abnormal width value group. The control circuit 40 that executes the determination process in step S120 corresponds to an example of a “second determination unit” recited in the claims.

If it is determined that the first minority width value group is an abnormal width value group as described above, a first correction processing subroutine is executed in step S121. The control circuit 40 that executes the first correction processing in step S121 corresponds to an example of “correction means” recited in the claims. In the subroutine of the first correction process, first, an initial condition setting process is performed in step S201 of FIG. In this process, the total number n of each bar constituting the abnormal width value group, the first threshold value W _th1 and the second threshold value W _th2 are set. In the present embodiment, of the percentages where the first average width value W _a is 0% and the second average width value W _b is 100%, the value of 35% is the first threshold value W _th1 and the value of 65% is the second value. The threshold value _Wth2 is set. Note that the values of the first threshold value W _th1 and the second threshold value W _th2 can be changed as appropriate according to the type of the barcode B to be read. In addition, in this initial condition setting process, k = 1 is set in order to process the width value of the k-th bar from the smallest bar value among the n bars constituting the abnormal width value group as W _k. The

Next, in step S203, the width value W _k bars abnormal width value population is determined whether it is less than the first threshold value W _th1. Since at this stage it is k = 1, so that the smallest bar width value W ₁ of constituting the abnormality width value population is determined whether it is less than the first threshold value W _th1. Then, (Yes in S203), if the width value _{W 1} is determined that the first threshold value _{W th1} or less, the width value _{W 1} the first average width value W than the difference between the second average width value _{W b} as the difference between _a small, at step S205, the width value W ₁ is set to be equal to the first average width value W _a. On the other hand, it is determined if the width value _{W 1} is determined to be larger than the first threshold value _{W th1} (at S203 No), at step S207 the width value _{W 1} is about whether or not the second threshold value _{W th2} or more . Then, (Yes in S207), if the width value _{W 1} is determined with a second threshold value _{W th2} or more, the width value _{W 1} and the second average width value W than the difference between the first average width value _{W a} as the difference between _b is small, in step S209, the width value W ₁ is set to be equal to the second average width value W _b. On the other hand, the width value _{W 1} when it is determined that the second less than the threshold value _{W th2} (No in S207), the subroutine of individual correction processing described below at step S211 is executed.

As described above, the width value _{W 1} of the bars abnormal width value population when corrected by one of steps S205, S209, S211, a determination is made whether k ≧ n at step S213. That is, if the first correction process has not been performed for all the bar width values W _k of the abnormal width value group, it is determined No in step S213, 1 is added to k in step S215, and step S203. The process from is repeated. At this stage, since k = 1, if n is 2 or more, it is determined No in step S213, k = 2 is set in step S215, and the processing from step S203 is repeated. Become. On the other hand, since the first correction process has been performed for all the bar width values W _{k of} the first minority width value group, if k ≧ n (Yes in S213), the subroutine of the first correction process ends.

Here, the individual correction process described above will be described with reference to the flowchart of FIG.
In this individual correction processing, predefined width value of characters including a bar abnormal width value W _k (hereinafter, also referred to as prescribed width value), based on the width values of the other normal bar included in the character Thus, the width value W _k of the bar of the abnormal width value group is corrected. Specifically, in the subroutine of individual correction processing, first, in step S301 of FIG. 5, the character extraction processing is performed, characters are extracted one that includes bar width value W _k. Next, in step S303, it is determined whether or not there is one abnormal width value bar among the bars constituting the extracted character. When the bar abnormality width values within the extraction character exists bars only one width value W _k is determined as Yes at step S303, the first abnormal width value correction process is performed at step S305 The

In this first abnormal width value correction process, the width value W _k is calculated from each of the normal width values (that is, the specified width value to be uncorrected) in the extracted character from the specified total number of modules constituting one character. Correction is made to be equal to a value obtained by subtracting the sum of the number of modules constituting the module. To explain based on specific numerical values, for example, as shown in FIG. 8A, the value corresponding to the number of modules of the abnormal width value is 0.6, and the value corresponding to the number of modules of the normal width value is When 4, 1, 1 is three, a value corresponding to the number of modules in width value W _k bars abnormal width value population, 7 (1 total number of modules constituting the character) from 6 (normal width value This is corrected to 1 which is a value obtained by subtracting the total number of modules constituting the bar (see FIG. 8B).

  On the other hand, if it is determined No in step S303, it is determined in step S307 whether or not there are two bars having abnormal width values among the bars constituting the extracted character. If there are two abnormal width value bars in the extracted character, “Yes” is determined in step S307, and second abnormal width value correction processing is performed in step S309.

  In this second abnormal width value correction process, first, the sum of the number of modules constituting each bar of the normal width value in the extracted character is subtracted from the prescribed total number of modules constituting one character, and two correction target two values are subtracted. Find the total number of modules in the bar. Since the corrected module pattern assumed from the total number of modules of the correction target bar is limited as shown in FIG. 9A, the total number of correction target modules is 2 according to this module pattern. In this case, each abnormal width value is corrected to a value corresponding to 1 in terms of the number of modules. When the total number of modules to be corrected is 3, the smaller one of the two abnormal width values is corrected to a value corresponding to 1 in the number of modules, and the larger one is corrected to a value corresponding to 2 in the number of modules. When the sum of the number of modules to be corrected is 4, if the difference between the two abnormal width values is less than the value corresponding to 1 in the number of modules, the number corresponding to 2 in the number of modules is set to 2 respectively. If the difference between the two abnormal width values is greater than or equal to the value corresponding to 1 in the number of modules, the smaller one is corrected to a value corresponding to 1 in the number of modules, and the larger one is corrected to a value corresponding to 3 in the number of modules. Further, when the sum of the number of modules to be corrected is 5, if the difference between the two abnormal width values is less than the value corresponding to 2 in the number of modules, the smaller one is set to a value corresponding to 2 in the number of modules. The larger one is corrected to the value corresponding to 3 in the number of modules, and if the difference between the two abnormal width values is greater than or equal to the value corresponding to 2 in the number of modules, the smaller one is larger in the value corresponding to 1 in the number of modules. The number of modules is corrected to a value corresponding to 4.

  For example, as shown in FIG. 9B, the values obtained by converting the abnormal width value into the number of modules are 1.6 and 2.4, and the normal width value is set as the number of modules. Assuming that the converted values are 2 and 2, first, the total number of modules to be corrected is 4 by subtracting 3 from 7. Since the total number of modules to be corrected is 4, the assumed corrected module pattern is 1: 3 or 2: 2. Here, since the value obtained by converting the difference between the two abnormal width values into the number of modules is 0.8 and less than 1, the two abnormal width values are corrected to values corresponding to 2 in the number of modules, respectively. (See FIG. 9C).

  On the other hand, if it is determined No in step S307, it is determined in step S311 whether or not there are three abnormal width value bars among the bars constituting the extracted character. If there are three bars with abnormal width values in the extracted character, “Yes” is determined in step S311 and third abnormal width value correction processing is performed in step S313.

  In the third abnormal width value correction process, first, each bar of the normal width value in the extracted character is formed from the specified total number of modules constituting one character, as in the second abnormal width value correction process described above. The total number of modules is subtracted to obtain the total number of modules of the three bars to be corrected. Since the corrected module pattern assumed from the total number of modules of the correction target bar is limited as shown in FIG. 10A, the total number of correction target modules is 3 according to this module pattern. In this case, each abnormal width value is corrected to a value corresponding to 1 in terms of the number of modules. When the total number of modules to be corrected is 4, the largest one of the three abnormal width values is corrected to a value corresponding to 2 in the number of modules, and the other is corrected to a value corresponding to 1 in the number of modules. . When the total number of modules to be corrected is 5, if the difference between the largest value and the second largest value among the three abnormal width values is less than the value corresponding to 1 in the number of modules, the smallest value Is corrected to a value corresponding to 1 in the number of modules, and other values are corrected to a value corresponding to 2 in the number of modules. If the difference between the largest value and the second largest value among the three abnormal width values is greater than or equal to 1 in terms of the number of modules, the largest value is corrected to a value corresponding to 3 in the number of modules. The other values are corrected to a value corresponding to 1 in the number of modules. Furthermore, when the total number of modules to be corrected is 6, if the difference between the largest value and the smallest value among the three abnormal width values is less than the value corresponding to 1 in the number of modules, all values Is corrected to a value corresponding to 2 in the number of modules. In addition, the difference between the largest value and the smallest value among the three abnormal width values is equal to or greater than 1 in terms of the number of modules, and the difference between the largest value and the second largest value is the number of modules. If the value is less than 2, the largest value is equivalent to 3 in the number of modules, the second largest value is equivalent to 2 in the number of modules, and the smallest value is 1 in the number of modules. Correct to the corresponding value. Furthermore, if the difference between the largest value and the second largest value among the three abnormal width values is greater than or equal to 2 in the number of modules, the largest value is changed to a value corresponding to 4 in the number of modules. A value other than is corrected to a value corresponding to 1 in terms of the number of modules.

  If it demonstrates based on a specific numerical value, as shown in FIG.10 (B), for example, the value which converted the abnormal width | variety value into the number of modules is three of 1.4, 2.4, 2.6, If there is only one value obtained by converting the normal width value into the number of modules and the value is 1, first, the total number of modules to be corrected is 6 by subtracting 1 from 7. Since the total number of modules to be corrected is 6, the assumed corrected module pattern is either 1: 1: 4, 2: 2: 2, or 1: 2: 3. Here, out of the three abnormal width values, the value obtained by converting the difference between the largest value and the smallest value into the number of modules is 1.2, and the difference between the largest value and the second largest value. Since the value converted into the number of modules is 0.2, the three abnormal width values are the values converted into the number of modules: 1.4 is 1, 2.4 is 2, and 2.6 is 3, respectively. It is corrected (see FIG. 10C).

On the other hand, if it is determined No in step S311, the fourth abnormal width value correction process is performed in step S315. Here, the determination of No in step S311 means that there is no normal width value and only an abnormal width value in the extracted character. In the fourth abnormal width value correction process, the four abnormal width values are corrected to rounded values. Explaining based on specific numerical values, for example, as shown in FIG. 11A, the abnormal width value is a value converted into the number of modules, which is 4 of 0.6, 1.6, 3.4, and 4.4. Assuming that the value is one, each value is rounded off, and 0.6 is corrected to 1, 1.6 is corrected to 2, 3.4 is corrected to 3, and 4.4 is corrected to 4 (FIG. 11B). reference).
In this way, the abnormal width value _Wk is corrected in any of the abnormal width value correction processes, whereby the individual correction process subroutine ends.

On the other hand, in step S119 of FIG. 3 described above, the normal width value group having a large average width value and the normal width having a small average width value with respect to the width value of each bar of the first minority width value group extracted as described above. If only one of the value groups exists, it is determined No in step S119, and the second correction process is performed in step S123. In the second correction processing, based on the average width value of the normal width value group existing in one of the first minority width value groups and the average width value of another normal width value group having a small difference between the average width values. Thus, the width value of each bar of the first minority width value group is corrected. Specifically, for example, as small width values populations S ₂ shown in FIG. 7, the first normal width value population C of the second small average width value absent the normal width value population C ₂ large average width value _When only ₁ exists, this minority width value group S ₂ has a small difference between the first average width value W _{a of} the first normal width value group C ₁ and the first average width value W _a. Is corrected based on the average width value of the normal width value group (average width value W _c of the normal width value group C ₃ shown in FIG. 7).

If it is determined in step S120 described above that the width value of each bar of the first minority width value group is not abnormal (No in S120), a third correction process is performed in step S124, and the widths of all bars are determined. The value is set to be equal to the normal width value assumed in relation to both average width values W _a and W _b .

  Thus, when the width value of each bar of the first minority width value group is corrected in the processing of steps S121, S123, and S124, whether or not the correction is completed for all the minority width value groups in step S125. Determined. If correction has not been completed for all of the minority value group, it is determined No in step S125, and one minority value group that has not been corrected yet is extracted in step S127. The process from step S119 is repeated for the set minority value group.

On the other hand, when the correction has been completed for all the minority width value groups, it is determined Yes in step S125, and in step S129, based on the width value corrected in the processing from step S109 to step S125 described above. Re-decoding processing is performed, and the reading processing ends. In this re-decoding process, the abnormal width value W _{k and the} like are appropriately corrected as described above, so that even a barcode including a bar whose original width value has changed due to uneven printing or the like has been successfully decoded. can do.

As described above, in the optical information reading apparatus 10 according to the present embodiment, when decoding fails, a plurality of groups composed only of bars whose calculated width values are approximated are created by the group creation process. Furthermore, among the groups created by the group creation process in the first determination process, a group in which the total number of bars is equal to or greater than the predetermined number is determined as a normal width value group, and the total number of bars is less than the predetermined number. Is determined to be a minority value group. In addition, among the minority width value groups, a group composed of bars determined to be abnormal width values based on a difference from the width value of each bar of each normal width value group by the second determination unit is an abnormal width. Judged as a value group. Then, the abnormal width value W _k of each bar constituting the abnormal width value group is corrected based on the difference from the width value of each bar of each normal width value group, and is decoded using the corrected correction width value. Re-decoded by means.

As a result, when decoding of a barcode including a bar having an abnormal width value W _k whose original width value has changed due to uneven printing or the like has failed, the bar having the abnormal width value W _k has a width that approximates the width value. Since the value bar is small, it is included in the abnormal width value group and is corrected based on the difference between the width value of each bar in the normal width value group. Thereby, the width value changed due to printing unevenness or the like is appropriately corrected to the original width value, and a decrease in reading accuracy can be suppressed.
In the present invention, regardless of the total number of the width values of the black bars and Kakushiro bars, it is corrected abnormal width value W _k By only the width value a relative comparison. Therefore, correction can be performed without depending on the number of modules, not to mention barcodes in which the number of modules constituting one character is fixed (for example, EAN-13, EAN-8, UPC-A, etc.) In addition, it is possible to correct even a barcode whose number of modules is not fixed.

Then, the abnormal width value W _k of each bar constituting the abnormal width value group is corrected by a correction process based on the difference between the average width values W _a and W _{b of} each bar constituting each normal width value group. It is configured. Thus, by using the average width values W _a and W _b of each bar of each normal width value group, even if the width values of each bar of each normal width value group vary, an abnormal width value group is formed. abnormal width value W _k of each bar is properly corrected, it is possible to suppress the reduction in reading accuracy.

Further, when the first normal width value population C ₁ and the second normal width value population C ₂ exists for the abnormal width value population, abnormal width value W _k of each bar constituting the abnormality width value population, the than the difference between the 2 average width value W _b is corrected to be equal to the first average width value W _a when the difference between the first average width value W _a is small, the first average width value W _a It is corrected to be equal the to the second average width value W _b when the difference between the second average width value W _b is smaller than the difference. Thereby, the abnormal width value W _k of each bar constituting the abnormal width value group can be appropriately corrected using the average width value of the normal width value group closest to the respective width value.

In the case of either one only first normal width value population C ₁ and the second normal width value population C ₂ exists for the minority width value population, the width values of the bars of the small width value population The correction is made based on the average width value of one normal width value group that exists and the average width value of another normal width value group in which the difference between the average width values is small. Thereby, for example, since the width value of each bar of the minor width value group is larger than the average width value of each normal width value group, the second normal width value group C ₂ does not exist and the first normal width value group C ₁ Even when only the first average width value W _a is present, the first average width value W _{a of} the first normal width value group C ₁ and the average width value of another normal width value group having a small difference between the first average width value W _a Based on this, the width value of each bar of the minority width value group can be appropriately corrected.

Then, the abnormal width value W _k of each bar constituting the abnormality width value population, the abnormal width value W first average width for _{the k-value} W second average width value for the difference and the abnormal width value W _k of _a W _b if the difference is approximated, as corrected by the individual correction processing based on the the specified width value of the character comprising a bar of abnormal width value W _k, the width values of the other bar included in the character It is configured. Thus, since the difference between the average width values W _a and W _b with respect to the abnormal width value W _k is approximate, the abnormal width value W _k is corrected to both the average width values W _a and W _b. Even if there is a possibility, the abnormal width value W _k is calculated based on the specified width value of the character including the bar of the abnormal width value W _{k and} the width values of other bars included in the character. It is possible to appropriately correct either the first average width value W _a or the second average width value W _b .

In addition, this invention is not limited to the said embodiment, You may actualize as follows, and even in that case, an effect | action and effect equivalent to the said embodiment are acquired.
In the above embodiment, the barcode of EAN-13 has been described as an example. However, the barcode to be read is not limited to this, and barcodes such as EAN-8, UPC-A, CODE-39, and CODE-128 are used. Also has the above-mentioned effects. In this way, when a barcode with a standard different from EAN-13 is to be read, in the individual correction process in step S211, correction according to the standard such as the specified width value is performed.

DESCRIPTION OF SYMBOLS 10 ... Optical information reader 28 ... Light receiving sensor (light receiving means)
40. Control circuit (width value calculation means, decoding means, group creation means, first determination means, second determination means, correction means)
C ₁ , C ₂ ... normal width value group S ₁ , S ₂ ... minority width value group (abnormal width value group)
B ... Barcode R ... object W a _... first average width value W b _... second average width value W k _... abnormal width value

Claims (5)

An optical information reading apparatus capable of reading a barcode having a plurality of characters each formed by arranging a plurality of dark color and light color regions composed of one or more unit modules,
A light receiving means for receiving reflected light from the barcode;
Width value calculating means for calculating the width value of each region based on a light receiving signal output from the light receiving means;
Decoding means for decoding each character based on each width value;
A group creating means for creating a plurality of groups composed of only the regions of which the width value approximates among the regions;
Among the groups created by the group creating means, a group of a predetermined number or more that is regarded as the total number of the regions of the same width value constituting the barcode is determined as a normal width value group, First determination means for determining a group in which the total number of each region is less than the predetermined number as a minority width value group;
Among the minority width value groups, a group composed of regions determined to be abnormal width values based on the difference between the width values of the respective regions of the normal width value groups is determined as an abnormal width value group. A second determination means;
Correction means for correcting the width value of each region constituting the abnormal width value group based on a difference from the width value of each region constituting at least one of the normal width value group,
With
The decoding means re-decodes using the correction width value corrected by the correction means when decoding of the character based on the width value of each area calculated by the width value calculation means fails. An optical information reading device.   The correction means corrects the width value of each region constituting the abnormal width value group based on a difference from the average width value of each region constituting at least one of the normal width value groups. The optical information reader according to claim 1. The correction means, the width value of each region constituting the abnormal width value group,
A first normal width value group, which is a normal width value group composed of areas of average width values having a small difference from the width value, and is a normal width value group having an average width value smaller than the width value, and the width There is a second normal width value group that is a normal width value group having an average width value larger than the value, and the average width values of the first normal width value group and the second normal width value group are set as the first average width value and the first normal width value group. 2 When setting the average width value
When the difference from the first average width value is smaller than the difference from the second average width value, the correction is made to be equal to the first average width value, and the difference from the first average width value is more than the difference from the first average width value. 3. The optical information reading apparatus according to claim 1, wherein when the difference from the second average width value is small, correction is performed so as to be equal to the second average width value. 4.   The correction means includes only one of the first normal width value group and the second normal width value group for the width value of each region constituting the abnormal width value group. In this case, the correction is performed based on the average width value of one existing normal width value group and the average width value of another normal width value group in which a difference between the average width value is small. 4. The optical information reading device according to 3.   The correction means approximates the width value of each region constituting the abnormal width value group by a difference between the first average width value with respect to the width value and a difference between the second average width value with respect to the width value. 4. The optical information reading according to claim 3, wherein the correction is performed based on a prescribed width value of the character including the area of the width value and a width value of another area included in the character. apparatus.

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