JP4442512B2 - Information code reading apparatus and information code reading method - Google Patents

Description

  The present invention relates to an information code reading device and an information code reading method for optically reading an information code.

  The information code reading device has a function of capturing a two-dimensional image including an information code formed by combining a bright pattern and a dark pattern, and decoding the information code included in the captured two-dimensional image. This type of information code reader is disclosed in, for example, Patent Document 1 and Patent Document 2.

In the information code reading method disclosed in Patent Document 1, an inspection area is set by dividing a two-dimensional image into a matrix, and a light / dark change is detected based on a light / dark pattern along the main scanning line in each inspection area. ing. Then, the number of change points of light and darkness is compared with a predetermined value, an array table of inspection areas that are greater than or equal to the predetermined value and inspection areas that are less than the predetermined value is created, and an inspection area group that is close to the center of the image area and has a large area exists Estimated as a region. According to this method, since the information code can be decrypted based on the estimated presence area, it is possible to shorten the time required for the decryption to be completed. Patent Document 2 also discloses a similar method for estimating an existence region.
JP 2000-353210 A JP 2002-304594 A

  In recent years, information code readers have been developed that can read both one-dimensional barcodes and two-dimensional codes with a single terminal. Information codes are standardized in various ways, and it is necessary to perform a decoding process after discriminating these information code types. However, in the techniques described in Patent Document 1 and Patent Document 2 described above, when performing the decryption process, the decryption process is executed assuming that the information code is a certain kind of information code (for example, DataMatrix code). If the setting is incorrect, the decryption process cannot be completed. As a result, it is necessary to perform the decryption process again assuming that the information code is of another type, and the process until the completion of the decryption becomes enormous, which may increase the processing time.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to accelerate the decoding process in an apparatus capable of reading both a one-dimensional barcode and a two-dimensional code with a single terminal. An information code reader and an information code reading method are provided.

According to the first aspect of the present invention, the inspection line setting means sets a plurality of parallel inspection lines so as to intersect a bright pattern or a dark pattern included in the two-dimensional image captured by the imaging means, and brightness The level detection means detects a luminance level pattern that changes along the inspection line set by the inspection line setting means for each of the plurality of inspection lines, and the one-dimensional barcode determination means is detected by the luminance level detection means. The brightness level patterns of multiple inspection lines are compared with each other, and when it is determined that they are similar, the information code is determined as a one-dimensional barcode, and the decoding means determines that the determination result by the one-dimensional barcode determination means is one-dimensional. When it is a barcode, the information code is decoded by applying a decoding algorithm for a one-dimensional barcode, and when the determination result is another information code, For decrypting by applying the decryption algorithm other information code, it is possible decoding means, it is determined whether or not the one-dimensional bar code before performing the decryption process is included in the two-dimensional image. As a result, the processing can be speeded up as compared with the case where the decoding process is performed without determining whether the information code is a one-dimensional bar code or another information code.

  According to the invention described in claim 2, the inspection line setting means detects a boundary line between the bright area and the dark area in the two-dimensional image, on the condition that the detected boundary line is linear. Since a plurality of inspection lines that are orthogonal to the boundary line and separated from each other by a predetermined distance are set, it is possible to set the inspection lines so as to surely intersect the bright pattern or the dark pattern.

  According to the invention described in claim 3, the inspection line setting means specifies one light / dark boundary point located at the boundary between the light region and the dark region in the two-dimensional image, and uses the specified light / dark boundary point as a starting point. Since the boundary line is detected by tracing the boundary, even if there are other bright areas or dark areas away from the boundary, the boundary lines can be detected without erroneously detecting these bright areas or dark areas. it can.

  According to the fourth aspect of the present invention, the estimating means estimates the existence area of the information code included in the two-dimensional image captured by the imaging means, and the inspection line setting means is the information code estimated by the estimating means. A rough center position is calculated in the existence area, a rough tilt angle of the information code is calculated, a center line is set so as to pass through the calculated center position with the tilt angle, and the light and darkness that is the starting point on this center line Since the boundary point is set, the light / dark boundary point can be reliably set.

  According to the invention described in claim 5, the luminance level detecting means has the largest number of bright patterns and dark patterns constituting one code word among various one-dimensional barcodes to be decoded by the decoding means. The maximum number is set as the minimum detection pattern number, and for each inspection line, at least the minimum detection pattern number of brightness level patterns consisting of the brightness levels corresponding to the bright pattern and the dark pattern are detected. The luminance level pattern of the one-dimensional bar code can be reliably detected, and it is not necessary to detect the luminance level pattern corresponding to all the code words, thereby speeding up the processing.

  According to the sixth aspect of the present invention, the one-dimensional bar code discriminating unit obtains the distance between the extreme points of the luminance level for each of the luminance level patterns of the plurality of inspection lines, and corresponding poles between the inspection lines. Since it is determined that the luminance level patterns of the plurality of inspection lines are similar to each other on the condition that the ratio of the distances between the value points is within a predetermined range, it can be easily determined whether or not they are similar.

Hereinafter, an embodiment in which the present invention is applied to an information code reader configured to optically read a one-dimensional bar code and a QR code (two-dimensional code) as a kind of information code will be described with reference to FIG. Description will be made with reference to FIG.
FIG. 3 schematically shows an electrical block configuration of the information code reader. The information code reader 1 uses a battery 2 such as a secondary battery as a drive source, and decodes information expressed by an information code P (see FIG. 7) displayed in the image capture target area X to optically read the information code reader 1. It has a function to read.

The information code reader 1 includes a control circuit 3 comprising a CPU, a memory 4, a trigger switch 5, an operation switch 6, an LED 7, a buzzer 8, a liquid crystal display 9, a communication interface 10, a synchronization signal generation circuit 11, an address generation. A circuit 12, an irradiation unit 13, an imaging unit 14, a two-dimensional image sensor 15, an amplification circuit 16, an A / D conversion circuit 17, and a specific ratio detection circuit 18 are provided.
The memory 4 includes an image memory 4, a program storage area, and a work memory. The control circuit 3 has functions as decoding means, inspection line setting means, luminance level detection means, one-dimensional barcode determination means, and estimation means. The two-dimensional image sensor 15 is composed of an area sensor and functions as an imaging unit.

  The irradiation unit 13 is formed by arranging a plurality of LEDs (not shown) on a ring-shaped frame, for example, and irradiates the image capture target area X with light based on the control of the control circuit 3. The image forming unit 14 is configured by a lens, for example, and forms an image of the light reflected on the image capture target region X on the two-dimensional image sensor 15. The two-dimensional image sensor 15 is composed of, for example, a CCD or a CMOS image sensor and has a function of capturing a two-dimensional image. The two-dimensional image sensor 15 forms an image on the two-dimensional image sensor 15 based on the synchronization signal generated by the synchronization signal generation circuit 11. Light is photoelectrically converted, and the converted pixel signal is supplied to the amplifier circuit 16.

  This pixel signal is stored as image data of serial data in the image memory 4a in the memory 4 through the amplifier circuit 16 and the A / D conversion circuit 17 based on the synchronization signal generated by the synchronization signal generation circuit 11. Yes. At this time, the image data stored in the image memory 4a is image data including, for example, 8-bit (256 levels) luminance data (lightness data: luminance information).

  The address generation circuit 12 is supplied with a synchronization signal from the synchronization signal generation circuit 11, and gives an address designating signal for designating the address of the memory 4 to the memory 4 when the synchronization signal is given. At this time, the control circuit 3 takes in the image data and sequentially stores the image data at designated addresses in the image memory 4a.

In addition, the control circuit 3 determines, for the pixel data of the image memory 4a, white pixels (corresponding to a bright point) whose luminance level is higher than a predetermined value based on the stored luminance level, and black pixels whose luminance level is lower than a predetermined value ( (Equivalent to a dark spot). Further, the control circuit 3 calculates the number of black and white changes (corresponding to the number of light and dark change points) based on the stored luminance level. The number of black and white changes refers to the number that changes from “white pixels” to “black pixels” and the number that changes from “black pixels” to “white pixels” for pixel data that are adjacent in the horizontal or vertical direction. The total number for each area is shown.
At this time, as one of the methods for calculating the number of black and white changes from the luminance level of the image data, the first and second differential values are obtained for the luminance level of the pixel data continuous in the horizontal direction and the vertical direction, respectively. There is a method of calculating the number of black and white changes based on the differential value of.

The operation of the above configuration will be described with reference to FIGS.
In the present embodiment, the following description will be given on the assumption that pixel data for horizontal (horizontal direction) 640 pixels × vertical (vertical direction) 480 pixels is stored in the image memory 4a. The information code reader 1 is configured to be able to read both the information code P of the one-dimensional barcode B (see FIG. 7A) and the two-dimensional code H (see FIG. 7B). The following will be described.

  FIG. 1 and FIG. 2 schematically show the processing performed when the control circuit 3 optically reads the information code by a flowchart. First, when the control circuit 3 captures a two-dimensional image (step S1) and takes in the luminance level data of the pixels into the image memory 4a, for example, a matrix-shaped partition region K (see FIG. 4) for these pixel data. (Step S2). In this case, as shown in FIG. 4, for example, it is divided into a square shape of 32 pixels in the horizontal direction × 32 pixels in the vertical direction.

  Next, the control circuit 3 estimates the partitioned area K where the information code P exists based on the pixel data as the estimated existing area Kb (step S3). The estimation method of the existence region is not particularly related to the feature of the present embodiment, and thus detailed description thereof is omitted. However, the estimation method of Patent Document 1 or Patent Document 2 filed earlier can be applied. Then, the estimated presence area Kb can be specified.

  Next, the control circuit 3 sets the estimated center line C of the estimated existence area Kb (see FIG. 4) (step S4). The center line C is preferably set as follows, for example. That is, the control circuit 3 determines, for each partition area K constituting the estimated presence area Kb where the presence of the information code P is estimated, from the black and white change numbers (from “white pixels” to “white pixels” of the two-dimensional image. The number of points that change from “black pixel” or “black pixel” to “white pixel” is calculated.

  Thereafter, the control circuit 3 again selects a partition area K in which the ratio of the number of black and white changes in the horizontal direction and the vertical direction is within a predetermined range from among the partition areas K constituting the estimated existence area Kb as the estimated existence area Kb. good. That is, in the case of the one-dimensional barcode B, when the longitudinal direction of the “bar” and the longitudinal direction of the “space” are inclined at a certain inclination angle θ, the ratio of the black and white change points in the estimated existence area Kb is calculated. However, a bias occurs.

  For example, when the one-dimensional barcode B is inclined at an inclination angle θ of 45 degrees, the number of black-and-white changes is horizontal: vertical = 1: 1, and the ratio tends to be close to 1. For example, when the information code existing in the estimated presence area Kb is a two-dimensional code, it is chaotic without causing a bias. Therefore, at this stage, it is possible to determine with high probability whether or not it is a one-dimensional barcode B.

  Then, the control circuit 3 uses the ratio of the number of black and white changes in the horizontal direction and the vertical direction so that black pixels are continuous in the partitioned area K (black pixel group: one-dimensional barcode B, “bar”: dark pattern). Equivalent) or a portion where white pixels are continuous (white pixel group: in the case of the one-dimensional barcode B, “space”: equivalent to a bright pattern) is detected.

  Specifically, when the longitudinal direction of “bar” or “space” is extended along the vertical direction of the two-dimensional image, the number of black and white changes in the horizontal direction is large and the number of black and white changes in the vertical direction is zero. . In this case, if the “ratio” corresponding to the tilt angle θ is defined as (number of black and white changes in the vertical direction) ÷ (number of black and white changes in the horizontal direction), the ratio becomes zero. For this reason, the inclination angle θ is set to 0 degree.

  When the longitudinal direction of “bar” or “space” is extended along the horizontal direction, the number of monochrome changes in the vertical direction increases and the number of monochrome changes in the horizontal direction becomes zero. In this case, since the ratio becomes infinitely large, the inclination angle θ is set to 90 degrees. Further, along with the number of black and white changes, the number of black and white changes may be calculated in an oblique direction within the partition region K, and the approximate inclination angle θ may be calculated from these pieces of information. At this time, depending on the required accuracy of the angle of the center line C, a plurality of black and white changes may be set in the horizontal direction and the vertical direction with respect to the partitioned area K. Thereby, the inclination angle θ can be calculated with high accuracy.

  Next, the control circuit 3 calculates the average value of the calculated inclination angle θ for the partitioned area K where the presence of the information code P is estimated, thereby roughly increasing the inclination angle of the black pixel group or the white pixel group. θ and the approximate inclination angle θ in the vertical direction can be calculated. For example, the control circuit 3 sets the angle in the vertical direction of the average value of the calculated inclinations as the angle of the center line C.

  The control circuit 3 is located at the center between the two partition regions K located at the outermost part in the horizontal direction in the estimated partition region K (ie, the estimated existence region Kb) and at the outermost part in the vertical direction. A center line C is set with a center portion Ka (corresponding to the approximate center position) located at the approximate center between the two partitioned regions K.

  In the example of FIG. 4, the existence of the information code P is estimated so that the maximum number of the partitioned areas K in the vertical direction and the horizontal direction among the estimated existing areas Kb is an odd number (5 in the vertical direction, Therefore, the center line C may be set so that the center portion Ka of the partition area K located at the center of the estimated partition areas K is a passing point.

  In this case, when it is estimated that the information code P exists for the partition area K whose maximum number is an even number in both the vertical direction and the horizontal direction, among the estimated existence areas Kb, the central four partition areas K It is preferable to set a center line C having a center point Ka corresponding to the intersecting portion as a passing point. Thereby, it is possible to set the center line C with the approximate center of the estimated existence area Kb as a passing point. The center line C is set so as to surely pass through the central portion Ka of the estimated existence area Kb and to reliably intersect the black pixel group (bar B1) or the white pixel group (space B2). Will come to be.

  Next, the control circuit 3 sets the center line from one end point side (for example, the left side in the horizontal direction in FIG. 4) to the other end point side (for example, the right side in the horizontal direction in FIG. 4). A black pixel is searched as one light / dark boundary point located at the boundary between the light region and the dark region along C (step S5). Then, the control circuit 3 can specify a black pixel as a light / dark boundary point in the peripheral portion in the estimated existence region Kb. At this time, the control circuit 3 reliably passes the center line C so as to pass through the central portion Ka of the estimated existence area Kb and to reliably cross the black pixel group (bar B1) and the white pixel group (space B2). Because it is set, black pixels (boundary points) can be detected quickly and reliably.

  FIG. 5 schematically shows a procedure when the control circuit searches for a pixel. As shown in FIG. 5, when searching for a black pixel along the center line C, the control circuit 3 searches for and specifies a black pixel (start point) at a position A1, and then determines a predetermined predetermined value in the vertical upward direction. The target (bright / dark spot detection target) is moved by the number of pixels (step S6). The predetermined number of pixels is a number of pixels set in advance so as to follow the boundary line Z without being separated from the position A1 of the first searched black pixel by a predetermined distance or more, and in this case, for example, one pixel.

  In FIG. 5, the position A2 corresponds to the first position. At this time, the control circuit 3 determines whether the pixel at the position A2 is a white pixel or a black pixel (step S7). In this case, since the position A2 is a white pixel (step S7: white pixel), the control circuit 3 searches for a black pixel from the position A2 toward the right in the horizontal direction in the figure (step S8).

  At this time, the control circuit 3 sequentially determines whether the pixel is a black pixel or a white pixel every time a target is moved in the horizontal direction for each predetermined pixel (for example, one pixel). The distance (number of pixels) from A2 to position A3 is calculated (step S9). In the example of FIG. 5, the moving distance is calculated as one pixel.

  When the calculated moving distance is greater than a predetermined limit value (for example, 10 pixels) (step S10: YES), the control circuit 3 returns to the starting point position A1 (step S11), and FIG. Proceed to the processing routine shown. That is, if the process reaches the end in the longitudinal direction along the boundary of the black pixel group, it cannot be found by searching for the black pixel in the horizontal direction, or the next dark pattern (“bar” of the one-dimensional barcode) Since the corresponding black pixel is searched, the moving distance becomes long. In preparation for this case, a limit value of the movement distance is provided.

  When the moving distance is equal to or less than a predetermined limit value (step S10: NO), the control circuit 3 returns to step S6 and repeats the process. Then, the control circuit 3 can search the black pixels at positions A3, A5,... In FIG.

  On the other hand, although not shown, the case where the pixel detected in step S7 is a black pixel will be described. If the detected pixel is a black pixel when the target is moved by a predetermined pixel vertically upward in step S6 (step S7: black pixel), the control circuit 3 moves leftward in the horizontal direction in the figure. A white pixel is searched for every pixel (step S12), and when the white pixel is searched, the pixel is returned by one pixel (step S13), thereby searching for a black pixel located at the left end boundary.

  When the black pixel is searched, the control circuit 3 calculates a moving distance (number of pixels) (step S14). If the moving distance is larger than the limit value (step S15: YES), the control circuit 3 proceeds to step S11. However, if the moving distance is less than or equal to the limit value (step S15: NO), the process returns to step S6 and is repeated. As a result, the control circuit 3 can search for a black pixel located on the left end boundary in the horizontal direction with respect to the pixel vertically upward from the start point A1.

  The control circuit 3 repeats these processes for pixels vertically downward from the starting point A1 (steps S11 and S16 to S24). That is, when the control circuit 3 returns to the start point A1 in step S11, the control circuit 3 moves the target (light / dark point detection target) by a predetermined pixel in the vertical downward direction. If the detected position Ar1 is a black pixel, the control circuit 3 searches for a white pixel in the horizontal left direction (step S18). At this time, the control circuit 3 sequentially moves the detection target pixel to the positions Ar2, Ar3... For each pixel to determine whether or not it is a white pixel, but when searching for a white pixel at the position Ar3 in FIG. The pixel is returned (step S19).

  At this time, after confirming that the position Ar2 is a black pixel (step S19a), the control circuit 3 specifies the position Ar2 of the black pixel. If the position Ar2 is not a black pixel (step S19a: NO), it is determined that white pixels are gathered, the process proceeds to step S19, and the determination process is repeated by returning one pixel. This is performed in order to specify the position of the black pixel on the left end side boundary in the horizontal direction.

  Next, when the position Ar2 of the black pixel is specified, the control circuit 3 calculates the distance from the position Ar1 to the position Ar2 as described above (step S20), and the movement distance is larger than a predetermined limit value. It is determined whether or not (step S21). This is performed in order to detect the lower vertical end of the black pixel group in the longitudinal direction. That is, when the control circuit 3 determines that the moving distance is larger than the limit value, it cannot detect the black pixel or detects a black pixel of another pattern, so that the longitudinal direction of the black pixel group It is determined that the lower end of the vertical direction is detected, and the process proceeds to step S25.

  On the other hand, the case where the pixel detected in step S17 is a white pixel will be described. When the control circuit 3 detects that the pixel is a white pixel in step S17 when the target (light / dark spot detection target) is moved by a predetermined pixel in the vertical downward direction in step S16, the control circuit 3 moves the black pixel toward the horizontal right direction. Search is performed (step S22).

  The control circuit 3 searches for the black pixel for each pixel in the horizontal right direction. After the black pixel is searched, the control circuit 3 calculates the distance between the position and the reference position Ar1. When this distance is greater than the limit value, the control circuit 3 determines that the vertical end has been reached as described above, and proceeds to step S25, but when the movement distance is less than or equal to the limit value (step S24: NO) ), The process proceeds to step S16 and the process is repeated.

  When the control circuit 3 proceeds to step S25, it determines whether or not the extension direction of the searched black pixel group is linear (step S25). That is, it is determined whether or not a predetermined number or more of black pixels are detected as boundary points, and whether or not a group of black pixels exists substantially along a straight line. Specifically, the control circuit 3 sets a straight line such that the distance from all the black pixels is the shortest, and determines whether the distance of the black pixel from the straight line is within a predetermined range. It is good to make it.

  When it is determined that the extension direction of the black pixel group searched in step S25 is not linear, the control circuit 3 determines that it is not a one-dimensional barcode (step S26), and other information codes P The process proceeds to the decryption process (for example, the decryption process of the two-dimensional code) and ends. When the control circuit 3 determines that the extension direction of the searched black pixel group is linear (step S25: YES), for example, it detects the inclination angle θ in the extension direction of the linear black pixel group. After that, a plurality of perpendicular lines H1 to Hn (corresponding to inspection lines) that are perpendicular to the extending direction of the black pixel group are set (step S27). The perpendicular lines H1 to Hn are set parallel to each other. The control circuit 3 shifts to the decoding process of other information codes P without setting a plurality of perpendicular lines H1 to Hn when it is determined in step S26 that the barcode is not a one-dimensional barcode. Processing can be speeded up.

  The reason for setting a plurality of perpendicular lines in the extending direction of the straight black pixel group is to reliably determine whether or not the information code P included in the captured two-dimensional image is a one-dimensional barcode B. Because. In general, as shown in FIG. 7A, the one-dimensional barcode B has linear “bars B1 (black pixel group: dark pattern)” and “space B2 (white pixel group: bright pattern)” in a striped pattern. It is configured in combination.

  At the time of decoding, the control circuit 3 decodes and reads one-dimensionally in the direction perpendicular to the longitudinal direction of the bar B1 or space B2 of the one-dimensional barcode B, but in the longitudinal direction of the bar B1 or space B2. It is necessary to decode so that the same result is obtained even if the decoding position is shifted. However, the two-dimensional image may be picked up in an inclined state in which the posting surface of the two-dimensional image is inclined in the memory 4 as shown in FIG. Even in this case, the control circuit 3 needs to decode so that the same result is obtained.

  Therefore, in the present embodiment, the control circuit 3 sets a plurality of perpendicular lines H1 to Hn (step S27), detects a luminance level pattern (step S28), and determines whether or not these luminance level patterns are similar. After determining (step S29) and determining that it is a one-dimensional barcode on the condition that it is similar (step S30), the decoding algorithm of the one-dimensional barcode B is applied to perform the decoding process.

  In addition, if the control circuit 3 determines that it is not similar in step S29, it determines with it not being the one-dimensional barcode B (step S31). When the control circuit 3 determines that it is not the one-dimensional barcode B, it applies a decoding algorithm of other information code P (for example, two-dimensional code: see data matrix code, QR code, etc. in FIG. 7B). The decryption process is performed.

  When the control circuit 3 sets a plurality of perpendicular lines H1 to Hn, it is desirable to set as follows. If the control circuit 3 determines that the extending direction of the black pixel group located at the boundary searched in step S25 is linear, a line segment (straight line portion) obtained by connecting both end sides of these black pixel groups. Are used as passing points (corresponding to other light / dark boundary points) at a predetermined distance (for example, a distance of 3 pixels), and perpendicular lines H1 to Hn parallel to each other are inspected based on the calculated inclination angle θ. It is desirable to set it as a line. Specifically, as shown in FIG. 5, the control circuit 3 uses, for example, three pixels apart from the boundary points formed by the black pixels at the positions A1, A3, A5. The perpendicular lines H1 to Hn with the passing positions A1, A7,... As passing points can be set.

  In addition, the following may be used. When the control circuit 3 determines that the extension direction of the black pixel group searched in step S25 is arranged in a straight line, the control circuit 3 detects the length between the end portions of the line segments obtained by connecting these black pixel groups. A dividing point obtained by dividing the length into a predetermined number (for example, 5) is set as a passing point, and perpendicular lines H1 to Hn parallel to each other are set based on the calculated inclination angle θ. By setting the vertical lines H1 to Hn in this way, the vertical lines can be set more efficiently and it can be reliably determined whether or not the barcode is a one-dimensional barcode.

  The control circuit 3 sets a plurality of vertical lines H1 to Hn in step S27, detects the luminance level patterns J1, J2,... Along the plurality of vertical lines H1 to Hn in step S28, and in step S29, the plurality of luminance levels. It is determined whether or not the level patterns are similar. At this time, the control circuit 3 desirably performs the following processing.

  FIG. 6A shows an example of a luminance level detection waveform (luminance level pattern) along a plurality of vertical lines as a change signal of the luminance level for each of the set vertical lines H1 to Hn. As shown in FIG. 6A, the control circuit 3 has a minimum luminance level in a certain reference position (for example, the position of the black pixel A1: FIG. 6A) with respect to the luminance level pattern J1 corresponding to a certain vertical line H1. .., And distances X1, X3, X5... From the position of the pixel from which the maximum value of the luminance level is acquired (the position of the white pixel), and other minimum values of the luminance level are acquired from the reference position. Distances X2, X4, X6... To the pixel position (black pixel position) are detected.

  Next, with respect to the luminance level pattern J2 corresponding to a certain vertical line H2, the control circuit 3 determines the distance from the same reference position as described above to the pixel position where the maximum value of the luminance level (the extreme value in the white pixel direction) is acquired. .. Are detected, and distances Y2, Y4, Y6... From the reference position to the pixel position where the minimum luminance level (extreme value in the black pixel direction) is obtained are detected.

  Next, the control circuit 3 calculates a maximum value ratio between two luminance level patterns at the same position and a minimum value ratio between two luminance level patterns at the same position. That is, in FIG. 6A, the control circuit 3 calculates the ratios Y1 / X1, Y2 / X2, Y3 / X3,.

  At this time, the control circuit 3 determines that the number of bars B1 and spaces B2 constituting one code word among a plurality of one-dimensional barcodes (so-called one-dimensional barcodes described above) to be detected by the information code reader 1 is the number of bars B1 and spaces B2. The maximum one is specified and the maximum number is set as the minimum detection pattern number, and the luminance level patterns J1 to Jn corresponding to the minimum detection pattern number B1 and the space B2 are detected for each of the vertical lines H1 to Hn. It is desirable.

  This will be described below. The one-dimensional barcode B has many types of codes that can be currently used. For example, CODE39, NW7, CODE128, ITF code, so-called POS code (EAN-8, EAN-13, UPC-A, UPC-E), RSS code, and composite codes thereof.

  The code word indicates a unit constituting the internal data. In the case of the above-described one-dimensional barcode, the number of bars B1 and spaces B2 (also referred to as the number of patterns or the number of modules) per code word is as follows. It is prescribed. CODE39 (9 + 1 (space)), NW7 (7 + 1) (space), CODE128 (6), ITF code (10), POS code (4), RSS code (8) Has been.

  The information code reader 1 may have different types of one-dimensional bar codes that can be decoded according to its specifications. Therefore, it is necessary to change the code word setting according to the type of the one-dimensional barcode and to decode it, but the ratio of the luminance level pattern for determining the one-dimensional barcode is set to all of the one-dimensional barcodes. If the calculation is performed for codewords, it is a factor that hinders the speeding up of processing, and therefore it is not necessary to process all codewords.

  Therefore, in order to speed up the processing, it is desirable that the control circuit 3 calculates a ratio corresponding only to the luminance level pattern for one code word. In addition, when detecting only a luminance level pattern for one codeword, since one codeword is composed of a maximum of ten modules in order to apply to all the one-dimensional barcode types described above, control is performed. The circuit 3 may acquire information on the distances X1 to X10 to the positions corresponding to the 10 maximum and minimum values of the luminance level and the distances Y1 to Y10 to the positions, and calculate the ratio.

  The control circuit 3 sets the luminance level pattern on condition that these ratios Y1 / X1, Y2 / X2, Y3 / X3,... Are within a predetermined range (for example, 0.9 to 1.1). Judged to be similar. In this way, it is desirable to determine whether or not they are similar. This makes it possible to easily determine whether or not they are similar. Thereafter, the control circuit 3 performs a decryption process to which a decryption algorithm corresponding to the type of the information code P is applied, and outputs a process result. However, since this process has no characteristics, the description is omitted.

  According to the present embodiment, the following operational effects are obtained. A two-dimensional image is picked up by the two-dimensional image sensor 15. The next process is a process performed by the control circuit 3. The captured two-dimensional image is partitioned into rectangles. The existence area of the information code P is estimated for the partition area K. The number of black-and-white changes in the horizontal direction and the vertical direction is detected for each partitioned region K in the estimated presence region Kb where the presence of the information code P is estimated. From the ratio of the number of black and white changes, the inclination angle θ of the black pixel group or the white pixel group in the divided area K and the angle in the vertical direction thereof are roughly calculated as the inclination angle θ of each divided area K. An average value of the inclination angles θ of the divided areas K is calculated, and this value is calculated as a rough inclination angle θ of the center line C. Next, the center point Ka of the partition region K located at the center of the estimated partition regions K is set as a rough center position, the center point Ka is set as a passing point, and the calculated approximate slope A center line C of the angle θ is set.

  A black pixel is searched for the partitioned area K estimated along the center line C. After searching for the first black pixel A1, the object is moved in the vertical direction by a predetermined pixel, and it is determined whether the pixel at this position A2 is a white pixel or a black pixel. The processing is changed depending on whether the pixel at the position A2 is a white pixel or a black pixel, and the moving distance from the position A2 to the position A3 of the black pixel located in the horizontal direction is calculated. When this moving distance is larger than the limit value, this position is set as the position of the end point in the longitudinal direction of the black pixel group.

  These processes are performed in the vertical vertical direction, and it is determined whether or not the searched black pixels are linear, and on the condition that the black pixels are linear, the linear direction in which these black pixels are extended is determined. A plurality of vertical lines H1 to Hn are set, and brightness level patterns J1, J2,... Are set along the plurality of vertical lines H1 to Hn. When it is determined that the luminance level patterns J1, J2,... Are similar, it is determined to be a one-dimensional barcode B, and a decoding process is performed by applying a decoding algorithm for the one-dimensional barcode B.

  In short, the control circuit 3 sets a plurality of mutually parallel perpendicular lines H1 to Hn (inspection lines) so as to intersect the bar B1 constituting the information code P, and the information code P along the perpendicular lines H1 to Hn. A plurality of luminance level patterns J1, J2,... Are detected, and when it is determined that the plurality of luminance level patterns J1, J2... Of the detected information code P are similar to each other, the information code P is a one-dimensional barcode B. It is determined that there is a decryption process by applying a decryption algorithm for the one-dimensional barcode B.

  Therefore, since the decoding process is performed after determining whether the information code P included in the captured two-dimensional image is the one-dimensional barcode B or the other information code P, the processing is speeded up. can do.

  When the black pixel groups A1, A3, A5, Ar1, Ar4, Ar7,... Are determined not to be linear by the linearity determination process, the control circuit 3 can immediately determine that they are not one-dimensional barcodes. It is possible to improve the speed of processing.

(Other embodiments)
The present invention is not limited to the above embodiment, and for example, the following modifications or expansions are possible. If the present invention can be realized, the processing described in the above embodiment may be omitted as necessary.
Although the perpendicular points H1 to Hn are set by detecting the boundary points, the continuous portions of the black pixel group and the white pixel group are detected, and the inspection lines (perpendicular lines H1 to Hn) are perpendicular to the longitudinal direction of the continuous portions. ) May be set.

  The process of searching for the black pixels A2,..., Ar1,... May be performed in any manner as long as the search is performed at a position away from the black pixel A1 that is searched first. Further, various predetermined values may be set so that at least two or more black pixels are detected as a light / dark boundary point apart from the first searched black pixel A1 in the vertical direction of the center line C. In this case, it is possible to determine whether or not the shape is linear, and it is possible to obtain substantially the same function and effect as in the above-described embodiment.

The one-dimensional barcode B (information code P) may be a color code. You may apply the white pixel which comprises the space B2 as a boundary point.
After setting the partition area K and estimating the existence area of the information code P, the center line C is set and then the black pixel located at the boundary between the black pixel and the white pixel is detected. Processing and centerline setting processing may be provided as necessary.
A plurality of perpendicular lines H1 to Hn are set after determining whether or not the black pixels A1... Ar1 are linear, but this straight line determination processing may be provided as necessary.

1 is a flowchart schematically showing an operation of an information code reading apparatus according to an embodiment of the present invention (part 1). Flow chart schematically showing the operation of the information code reader (part 2) Block diagram schematically showing the electrical configuration Diagram showing estimated area and centerline of information code presence Operation explanation diagram when detecting a boundary point from the boundary point in the direction perpendicular to the center line (A) (b) The figure which shows a response | compatibility with the luminance level and position of the luminance level pattern on several perpendicular lines. Figures showing examples of information codes ((a) an example of a one-dimensional barcode, (b) an example of a two-dimensional code)

Explanation of symbols

  In the drawings, 1 is an information code reader, 3 is a control circuit (decoding means, inspection line setting means, luminance level detection means, one-dimensional bar code discrimination means), 15 is a two-dimensional image sensor (imaging means), and B is primary. An original barcode, H is a two-dimensional code, and P is an information code.

Claims (7)

Information having imaging means for capturing a two-dimensional image including an information code formed by combining a bright pattern and a dark pattern, and decoding means for decoding the information code based on the two-dimensional image captured by the imaging means In the code reader,
Inspection line setting means for setting a plurality of parallel inspection lines so as to intersect a bright pattern or a dark pattern included in the two-dimensional image imaged by the imaging means;
Brightness level detecting means for detecting a brightness level pattern that changes along the inspection line set by the inspection line setting means for each of the plurality of inspection lines;
A one-dimensional bar code discriminating means for comparing the luminance level patterns of the plurality of inspection lines detected by the luminance level detecting means with each other and discriminating the information code from a one-dimensional bar code when it is judged that they are similar to each other. And
The decoding means decodes the information code by applying a decoding algorithm of a one-dimensional barcode when the determination result by the one-dimensional barcode determination means is a one-dimensional barcode, and the determination result is other information code. An information code reading device characterized in that, in some cases, decoding is performed by applying another information code decoding algorithm .   The inspection line setting means detects a boundary line between a bright area and a dark area in the two-dimensional image, and is perpendicular to the boundary line and is mutually provided on the condition that the detected boundary line is linear. The information code reading apparatus according to claim 1, wherein a plurality of inspection lines separated by a predetermined distance are set.   The inspection line setting means specifies one light / dark boundary point located at the boundary between the bright region and the dark region in the two-dimensional image, and traces the boundary by tracing the boundary using the specified light / dark boundary point as a starting point. 3. The information code reading device according to claim 2, wherein a line is detected. An estimation unit that estimates an existence area of the information code included in the two-dimensional image captured by the imaging unit;
The inspection line setting means calculates a rough center position in the presence area of the information code estimated by the estimation means and calculates a rough inclination angle of the information code, and the calculated center position is calculated as the center position. 4. The information code reader according to claim 3, wherein a center line passing at an inclination angle is set, and a light / dark boundary point as the start point is set on the center line.   The luminance level detecting means identifies the maximum number of bright patterns and dark patterns constituting one code word among various one-dimensional barcodes to be decoded by the decoding means, and determines the maximum number. 5. The brightness level pattern comprising a brightness level corresponding to at least the minimum number of light detection patterns and dark patterns is set for each inspection line and set as the minimum number of detection patterns. The information code reading device according to any one of the above.   The one-dimensional bar code discriminating means obtains the distance between the extreme points of the luminance level for the luminance level patterns of the plurality of inspection lines, and the ratio of the distances between the corresponding extreme points between the inspection lines. 6. The information code reading device according to claim 1, wherein brightness level patterns of the plurality of inspection lines are determined to be similar to each other on the condition that is within a predetermined range. . In an information code reading method for decoding the information code from a two-dimensional image including an information code formed by combining a bright pattern and a dark pattern,
An inspection line setting process for setting a plurality of parallel inspection lines so as to intersect the bright pattern or the dark pattern included in the two-dimensional image;
A luminance level pattern detection process for detecting a luminance level pattern along each inspection line set by the inspection line setting process;
A one-dimensional barcode determination process for comparing the luminance level patterns of a plurality of inspection lines detected by the luminance level pattern detection process with each other and determining that the information code is a one-dimensional barcode when it is determined that they are similar to each other. ,
When the determination result of the one-dimensional barcode determination process is a one-dimensional barcode, the information code is decoded by applying a decoding algorithm for a one-dimensional barcode, and when the determination result is another information code, An information code reading method comprising: a decoding process for decoding by applying an information code decoding algorithm .

Images