JP2012240400A - Apparatus and method for quality inspection of corrugated cardboard sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inspection technology capable of accurately executing an inspection of misregistration even in printing of a corrugated cardboard sheet in which a strain of warpage or the like is easily caused.SOLUTION: A quality inspection apparatus of the corrugated cardboard sheet includes a storage means to store a relative position to a predetermined position as a reference value with regard to the predetermined position on a register mark to be printed on the corrugated cardboard sheet, an imaging means to image a print face on which the register mark is printed, an illumination means, a detection means to detect the relative position to the predetermined position as the relative position of a register mark based on image data obtained by being imaged with regard to the predetermined position of the printed register mark, and an operation means to calculate quantity of the misregistration along a carrying direction of the corrugated cardboard sheet and quantity of the misregistration along a width direction perpendicular to the carrying direction by comparing the detected the relative position of the register mark with the reference value stored in the storage means.

Description

  The present invention relates to an apparatus and a quality inspection method for detecting misregistration of corrugated cardboard sheets.

  In multi-color printing, there may be a misregistration that shifts the position of each color plate. The misregistration is a printing deviation with respect to a printed matter between the printing units. When a misregistration occurs, the pattern or character of the printed material is misaligned, which causes a visual problem. Therefore, registration is performed using a register mark on the printing material.

  As a conventional technique of a registration method using a registration mark, a first and a second in which a plurality of fine lines are arranged in parallel with each other at a predetermined pitch with respect to a cross or a T-shape formed at a center position such as a block or the like When the register marks with the fine line group added are used and the printing plates are overlapped, there is a register when the fine lines at the predetermined positions of the fine lines of the first fine line group and the second fine line group coincide with each other. Has been disclosed (for example, see Patent Document 1).

  Further, a register mark for color printing having a similar reference color mark and a measurement color mark whose centers coincide with each other is printed on paper, and the reference color mark printed on the paper and the measurement color mark are relative to each other. A method is disclosed in which a color misregistration in color printing can be easily determined visually by determining a misregistration as a misregistration (see, for example, Patent Document 2).

JP-A-7-164724 JP 2007-106042 A

However, when printing on a corrugated cardboard sheet, since the size of the sheet is large, the printing deviation also increases. Further, in the corrugated cardboard sheet, not only the distortion of the corrugated cardboard is already present before printing due to the use of glue and water vapor during the manufacturing process, but also water-based ink with high fluidity is used when performing flexographic printing on the corrugated cardboard sheet. As a result, the cardboard sheet is stretched, contracted, warped, and the like. Deformations such as expansion, contraction, and warpage are particularly likely to occur at the edges of the corrugated cardboard sheet, and it has been difficult for the prior art to accurately detect misregistration due to the above-described deformation in the printing of the corrugated cardboard sheet.
Therefore, an object of the present invention is to provide an inspection technique capable of accurately performing a registration error inspection even in the printing of a corrugated cardboard sheet that is likely to be warped or otherwise distorted.

  The quality inspection apparatus according to the first aspect includes storage means for storing, as a reference value, a relative position with respect to a predetermined position of the corrugated cardboard sheet for a predetermined position on the register mark to be printed on the corrugated cardboard sheet. Based on image data obtained by taking an image with the imaging means, an imaging means for imaging a printing surface of the cardboard sheet on which the mark is printed, an illumination means for illuminating an area imaged by the imaging means, and the cardboard Detection means for detecting a relative position of the registration mark printed on the sheet relative to the predetermined position of the corrugated cardboard sheet as a registration mark relative position, the registration mark relative position detected by the detection means, and the storage By comparing the reference value stored in the means along the conveying direction of the cardboard sheet It characterized in that it comprises a calculating means for calculating a misregistration amount along the width direction of the cardboard sheet which is perpendicular to the misregistration amount and conveyance direction.

A corrugated cardboard sheet quality inspection apparatus according to a second aspect is the corrugated cardboard sheet quality inspection apparatus according to the first aspect, wherein the calculation means has the register deviation amount within a predetermined allowable range. Whether or not
The image processing apparatus further includes output means for outputting data relating to the misregistration amount when the misregistration amount is not within a predetermined allowable value range.

  The corrugated cardboard sheet quality inspection apparatus according to the third aspect is the corrugated cardboard sheet quality inspection apparatus according to the second aspect, wherein the storage means is positioned at both ends with respect to at least the conveying direction of the corrugated sheet. For a predetermined position on a plurality of registration marks to be printed on, a relative position with respect to the predetermined position of the corrugated cardboard sheet is stored as a reference value, and the calculation means stores a plurality of registration marks detected by the detection means. The registration mark relative position is compared with the corresponding reference value, and the average registration deviation amount in the conveyance direction of the corrugated sheet at the plurality of registration marks and the average in the width direction of the corrugated sheet perpendicular to the conveyance direction. A misregistration amount is calculated, and it is determined whether or not the average misregistration amount is within a predetermined allowable range.

  A cardboard sheet quality inspection apparatus according to a fourth aspect is the cardboard sheet quality inspection apparatus according to any one of the first to third aspects, wherein the storage means is a reference dimension of the cardboard sheet. And the detection means detects the position of the corner of the cardboard sheet from the image data, and the calculation means prints the cardboard from the position of the corner of the cardboard sheet detected by the detection means. A sheet size is calculated, and the reference value is corrected based on a shift amount between the corrugated sheet size and the reference dimension, thereby calculating the registration shift amount.

  A cardboard sheet quality inspection apparatus according to a fifth aspect is the cardboard sheet quality inspection apparatus according to any one of the second to fourth aspects, wherein the storage means prints on the cardboard sheet. A predetermined reference color density level of the registration mark to be stored, and based on the image data obtained by the detection means being imaged by the imaging means, the color density of the registration mark printed on the cardboard sheet The level is detected, and the calculation means calculates the color density level deviation by comparing the color density level of the register mark with a reference color density level, and the color density level deviation is a predetermined allowable value. It is determined whether or not the color density level is within a range, and the output unit determines whether the color density level deviation is within a predetermined allowable range. And it outputs the data.

  A cardboard sheet quality inspection apparatus according to a sixth aspect is the cardboard sheet quality inspection apparatus according to any one of the second to fifth aspects, wherein the imaging means is the entire surface of the cardboard sheet. Image.

  A cardboard sheet quality inspection apparatus according to a seventh aspect is the cardboard sheet quality inspection apparatus according to the sixth aspect, wherein the storage means stores a reference image to be printed on the cardboard sheet, A detection unit detects an image printed on the cardboard sheet based on image data obtained by being imaged by the imaging unit, and the calculation unit is printed on the cardboard sheet detected by the detection unit. The quality is judged by comparing the obtained image with the reference image stored in the storage means.

  A quality inspection method for a corrugated cardboard sheet according to an eighth aspect includes a storage step of storing, as a reference value, a relative position with respect to a predetermined position of the corrugated cardboard sheet for a predetermined position on a register mark to be printed on the corrugated cardboard sheet; The corrugated cardboard with respect to a predetermined position of the register mark printed on the cardboard sheet based on an imaging process for imaging the corrugated cardboard sheet on which the register mark is printed, and image data obtained by imaging in the imaging process By comparing the detection position relative to the predetermined position of the sheet as the registration mark relative position, the registration mark relative position detected by the detection process and the reference value stored in the storage means, The amount of misregistration along the conveying direction of the cardboard sheet and the corrugated board perpendicular to the conveying direction Calculating a misregistration amount in the width direction of the sheet, and a determining calculating step whether the misregistration amount is within a predetermined range of tolerance.

  The cardboard sheet quality inspection apparatus according to any one of the first to fourth aspects uses the relative position of the predetermined position on the register mark to be printed on the corrugated cardboard sheet as a reference value. Since the deviation amount is calculated, it is possible to accurately detect the registration deviation even in the printing of the corrugated cardboard sheet which is likely to be distorted such as warpage.

  According to the corrugated cardboard sheet quality inspection apparatus according to the second aspect, when the misregistration amount is not within the predetermined allowable range, the data relating to the misregistration amount is output. It is possible to feed back data relating to the amount of deviation to the printing press.

  According to the cardboard sheet quality inspection apparatus according to the third aspect, the cardboard sheet transport direction of the registration mark printed at positions on both ends with respect to the transport direction, which is greatly affected by the expansion, contraction, and warp generated in the cardboard sheet. Since the average registration misalignment amount and the average registration misalignment amount in the width direction of the corrugated cardboard sheet orthogonal to the conveying direction are calculated, the misregistration amount due to the expansion, contraction, warpage, etc. generated in the corrugated cardboard sheet can be grasped more accurately. It becomes possible.

  According to the cardboard sheet quality inspection apparatus according to the fourth aspect, even when the size of the corrugated board sheet fluctuates due to causes such as expansion, contraction, warping, and sinking, the error of the misregistration amount can be reduced. It becomes possible.

  According to the corrugated cardboard sheet quality inspection apparatus according to the fifth aspect, the registration misregistration inspection and the color density level misalignment inspection can be accurately and simultaneously performed in the printing of the corrugated cardboard sheet, which is likely to be distorted. Quality and production efficiency can be further improved.

  According to the cardboard sheet quality inspection apparatus of the sixth aspect, since the imaging means images the entire surface of the cardboard sheet, the entire surface of the cardboard sheet can be inspected at once, greatly increasing the inspection speed and throughput. It becomes possible to up.

  According to the quality inspection device for a corrugated cardboard sheet according to the seventh aspect, since it is possible to inspect the design of the image printed on the cardboard sheet together with the registration error inspection, the quality inspection of the printed corrugated cardboard sheet Quality and speed can be improved.

  According to the cardboard sheet quality inspection method according to the eighth aspect, it is possible to obtain the same effect as the cardboard sheet quality inspection apparatus according to the first aspect.

It is a block diagram which shows the electrical constitution of the quality inspection apparatus of the cardboard sheet | seat which is 1st Embodiment of this invention. It is the schematic of the example which attached the quality inspection apparatus to the well-known printing apparatus. It is a figure which shows the example of the corrugated cardboard sheet in which the register mark was printed around the four corners. It is a figure for demonstrating a reference value. It is a figure which shows the example which the registration gap produced in the registration mark printed near the corner part on a cardboard sheet | seat. It is a flowchart which shows the procedure in which a quality inspection apparatus implements the registration shift detection and color density detection of one cardboard sheet. It is a figure which shows the example when shrinkage | contraction arises in the conveyance direction and width direction of a corrugated cardboard sheet. It is a flowchart which shows the procedure in which a quality inspection apparatus implements the registration deviation detection of one corrugated cardboard sheet, color density detection, and pattern deviation detection.

The present invention will be described in more detail with reference to the accompanying drawings.
[First embodiment]
<Configuration of cardboard sheet quality inspection device>

  FIG. 1 is a block diagram showing an electrical configuration of a cardboard sheet quality inspection apparatus 50 according to the first embodiment of the present invention. FIG. 2 is a schematic view of an example in which the quality inspection apparatus 50 is attached to a known printing apparatus 100. The quality inspection device 50 compares the data optically read by the CCD (Charge Coupled Device) camera 13 corresponding to the imaging means with the printed cardboard sheet 3 as an object to be inspected, and the plate (design) data. This is to detect a registration error and a color density error.

  As shown in FIG. 1, the quality inspection apparatus 50 is configured by connecting a control unit 11, a storage unit 12, a CCD camera 13, an illumination unit 14, an input unit 15, a communication unit 18, and a display unit 19 to a bus line 20. Has been.

  The control unit 11 is constituted by, for example, a CPU, determines the operation of the entire quality inspection apparatus 50 by executing a program stored in the storage unit 12 described later, and gives a command to the entire quality inspection apparatus 50. Moreover, the control part 11 also implement | achieves the function of the calculating part 16 and the detection part 17 which are mentioned later.

  As shown in FIG. 2, the quality inspection apparatus 50 includes a CCD camera 13 that images the upper surface of the printed cardboard sheet 3. The CCD camera 13 corresponding to the imaging means is fixedly disposed on the upper surface of the corrugated cardboard sheet 3 and images the entire surface of the corrugated cardboard sheet 3 that is a printed matter. By imaging the entire surface of the cardboard sheet 3, the entire surface of the cardboard sheet can be inspected at once, and the inspection speed and throughput can be greatly increased. A registration deviation is inspected by picking up an imaging portion of a registration mark to be inspected. It is also possible to inspect a pattern using an image obtained by imaging the entire surface of the cardboard sheet. In addition, it is not necessary to move the imaging unit in accordance with the imaging area, and the imaging unit can be fixedly arranged. Furthermore, in the case of partial imaging, there is a need for a process for timing each imaging and a process for determining an imaging area based on the plate data, but such a process is unnecessary because the entire surface is imaged at once. It becomes.

In addition to the CCD camera 13, for example, a known image sensor camera or the like can be used as the imaging means. The illumination unit 14 illuminates an area captured by the CCD camera 13 on the upper surface.

  The storage unit 12 is configured by a storage device such as a semiconductor memory, for example, and stores image data input from the CCD camera 13, a program executed by the control unit 11, information necessary for executing the program, and the like. . The input unit 15 is used for various inputs including selection of various functions by user operations. The input unit 15 includes an operation panel for inputting information such as numbers or characters, or an input device such as a keyboard.

  The calculation unit 16 calculates both a registration deviation amount along the conveyance direction of the cardboard sheet and a registration deviation amount along the width direction of the cardboard sheet perpendicular to the conveyance direction. Note that the calculation unit 16 may calculate one of the registration deviation amount along the conveyance direction of the corrugated cardboard sheet and the registration deviation amount along the width direction.

  The detection unit 17 detects the position of the corner of the cardboard sheet 3 and the position of the registration mark based on image data obtained by being imaged by the CCD camera 13.

  The communication unit 18 transmits and receives various data such as information on the dimensions of the cardboard sheet, information on the printing unit, information on the plate data, etc., with a printing machine connected to the network via a network such as a LAN or the Internet. Do. The communication unit 18 also functions as data output means as will be described later.

  The display unit 19 is configured by a display device such as a liquid crystal display, for example, and displays information instructed from the control unit 11. As will be described later, the display unit 19 also functions as a data output unit, like the communication unit 18.

  As shown in FIG. 2, the quality inspection device 50 is connected to the printing press 100 via a network 30 such as a LAN or the Internet. The printing machine 100 capable of multicolor printing is, for example, four-color printing, and includes four printing units 21, 22, 23, and 24 corresponding to each color. The printing units 21, 22, 23, and 24 are in the direction of conveyance of the corrugated cardboard sheet 3 indicated by the arrow F, the first color ink printing unit, the second color ink printing unit, the third color ink printing unit, and the fourth color printing unit. It is said.

In each printing unit, there are a plate cylinder 25, an impression cylinder 26, an ink transfer roll 27 for supplying ink to the plate cylinder 25 and transferring it, and an ink pan 28 for supplying ink 30 to the ink transfer roll 27. Is provided. The ink transfer roll 27 has a cell engraved on its surface and supplies a certain amount of ink to the plate cylinder 25. In printing, the corrugated cardboard sheet 3 passes through the printing units 21, 22, 23, and 24 and is subjected to printing pressure by the plate cylinder 25 and the impression cylinder 26 to imprint different color images on the corrugated cardboard sheet 3, Printing ends when the final printing unit 24 is exited. As will be described later, in the printing press 100, when the registration deviation amount calculated by the quality inspection apparatus 50 is not within the range of the predetermined tolerance, the XY axis two-dimensional direction is based on the registration deviation amount. The print position is adjusted.
<Register misregistration detection>

  Next, a registration error detection method for the corrugated cardboard sheet 3 will be described.

  The arithmetic unit 16 is configured to detect the registration mark 1 that is a relative position between a predetermined position on the edge of the printed cardboard sheet 3 detected by the detection unit 17 and a predetermined reference position on the printed registration mark 1. The relative position is calculated. Then, by comparing this with the reference value stored in the storage unit 12, the conveyance direction F of the cardboard sheet 3, that is, the registration deviation amount in the Y direction, and the width direction of the cardboard sheet 3 orthogonal to the conveyance direction F, that is, A misregistration amount in the X direction is calculated.

  In the present embodiment, the misregistration of the color registration mark printed on the corrugated cardboard sheet 3 is detected based on the color plate data. For example, the registration error detection is performed at the time of printing, and the print position is adjusted based on the registration error detection result. The quality inspection apparatus 50 prints a registration mark at a specific position of the corrugated cardboard sheet 3 (for example, near the adhesive margins at the four corners of the corrugated cardboard sheet 3) for the purpose of confirming the registration. To obtain an image data. Then, the misregistration amount is calculated using the edge of the corrugated cardboard sheet 3 as a reference, and it is determined whether or not the misregistration amount is within a predetermined allowable range. Then, when the registration deviation amount or the color density level deviation is not within a predetermined allowable range, the data relating to the registration deviation amount or the data relating to the color density level deviation is output, and each of the printing press 100 The registration data can be fed back to the printing units 21 to 24.

  First, the registration mark plate data (design data) and the dimension data of the cardboard sheet 3 are input from the input unit 19 or the communication unit 18 and stored in the storage unit 12. Based on the plate data and the dimension data of the corrugated cardboard sheet 3, the detection unit 17 calculates a relative position between a predetermined position on the edge of the corrugated cardboard sheet 3 and a predetermined position on the registration mark to be printed on the corrugated cardboard sheet 3. Detect as reference value. Then, the storage unit 12 stores the reference value. The reference position may be directly input from the input unit 19.

  FIG. 3 is a diagram illustrating an example of the corrugated cardboard sheet 3 in which the register marks 1 are printed around the four corners (corner portions O1, O2, O3, and O4) of the corrugated cardboard sheet 3. F is a conveyance (printing) direction. In the present embodiment, the register mark 1 is composed of first to fourth color portions using printing color inks used for the corrugated cardboard sheet 3 on which multicolor printing is performed. FIG. 3 shows an example of four register marks (1a to 1p) corresponding to four colors. Specifically, the first color registration mark is 1a, 1e, 1i, 1m, the second color registration mark 1b, 1f, 1j, 1n, the third color registration mark is 1c, 1g, 1p, 1o, and the fourth color registration mark. The marks are 1d, 1h, 1l, and 1p.

  In the present embodiment, an example in which a plurality of register marks 1 are printed in a plurality of corner regions of the cardboard sheet 3 is shown, but the position of the register marks 1 is not limited to this, and the cardboard sheet 3 is not limited thereto. A plurality of registration marks may be printed at one location, or one registration mark may be printed in a plurality of areas of the cardboard sheet 3. Further, only one register mark may be printed on the cardboard sheet 3. Calculate the amount of misregistration at the registration marks printed at the positions on both ends with respect to the cardboard sheet conveyance direction, which is greatly affected by the elongation, shrinkage, warpage, and sinking generated in the cardboard sheet as in this embodiment. Thus, it is possible to more accurately grasp the amount of misregistration caused by elongation, shrinkage, warpage, sinking, etc. occurring in the cardboard sheet.

  Next, the detection unit 17 detects a reference value that is a relative position of a predetermined position on the register mark 2 to be printed on the cardboard sheet 3 with respect to a predetermined position on the edge of the cardboard sheet 3. The reference value is stored in the storage unit 12. FIG. 4 is a diagram for explaining the reference value. Here, the registration mark 2a to be printed will be described as an example. In the present embodiment, the Y axis extends in parallel with the printing direction, and the X axis extends in a direction orthogonal to the printing direction, that is, across the corrugated cardboard sheet 3. In the present embodiment, the predetermined position on the edge of the corrugated cardboard sheet 3 is the corner O1, and the predetermined position of each register mark to be printed is the position of the center of gravity of each register mark. Assume that the relative position between the center of gravity 2at of the register mark 2a and the corner O1 is represented by XY coordinates. If the corner O1 is the origin (0, 0) and the coordinates of the center of gravity of the register mark 2a are (x2a, y2a), the reference values of the register mark 2a are X = x2a, Y = y2a.

  FIG. 5 is a diagram illustrating an example in which a registration deviation occurs in the registration marks 1 a to 1 d printed in the vicinity of the corner O <b> 1 on the cardboard sheet 3. The marks indicated by the broken lines 2a to 2d indicate the positions where the registration marks 1a to 1d indicated in the plate data are to be printed. That is, a shift between the printing positions of the registration marks 1a to 1d and the positions of the registration marks 2a to 2d indicated by broken lines 2a to 2d is a registration deviation. The detection unit 17 is based on the image data obtained by imaging the printing surface of the traveling cardboard sheet 3 with the CCD camera 13, and the center of gravity of the printed registration mark 1 and the corner O1 of the printed cardboard sheet 3. The position of is detected. The printed register mark 1a will be described as an example. The register mark relative position, which is the relative position between the center of gravity 1at of the register mark 1a and the corner O1, is represented by XY coordinates with the corner O1 as the origin (0, 0). Shall. If the corner O1 is the origin (0, 0) and the coordinates of the center of gravity of the register mark 1a are (x1a, y1a), the register mark relative position of the register mark 1a is X = x1a, Y = y1a.

  Next, the calculation unit 16 detects the relative position of the registration mark 1a detected by the detection unit 17 (relative position of the center of gravity 1at) and the reference value (relative to the center of gravity 2at of the registration mark 2a to be printed on the cardboard sheet 3). Position) and the registration deviation amount in the conveyance direction (arrow F, Y-axis direction) of the cardboard sheet 3 and the registration deviation amount in the width direction (X-axis direction) perpendicular to the conveyance direction are calculated. To do.

Specifically, since the reference values of the register mark 2a are X = x2a, Y = y2a, and the relative positions of the register mark are X = x1a, Y = y1a, the width direction of the corrugated cardboard sheet 3 of the register mark 1a The registration deviation amount sx1a in the (X-axis direction) is sx1a = x2a−x1a.
Further, the registration deviation amount sy1a in the conveyance direction (arrow F, Y-axis direction) of the corrugated cardboard sheet 3 is sy1a = y2a−y1a.

Then, the calculation unit 16 calculates the average misregistration amount in the conveyance direction of the corrugated cardboard sheet 3 and the average in the width direction of the corrugated cardboard sheet 3 orthogonal to the conveyance direction at the plurality of registration marks 1 of each color printed on the corrugated cardboard sheet 3. The misregistration amount is calculated and used as the misregistration amount of the printing. Specifically, the registration deviation in the first color registration marks 1a, 1e, 1i, and 1m printed at each of the four corners of the cardboard sheet 3 shown in FIG. 3 is the cardboard sheet of the registration marks 1a, 1e, 1i, and 1m. 3 in the width direction (X-axis direction) is sx1a, sx1e, sx1i, and sx1m, respectively, the average registration displacement amount Wx in the width direction (X-axis direction) of the corrugated cardboard sheet 3 at the first color registration mark is ,
Wx = (sx1a + sx1e + sx1i + sx1m) / 4.

  Further, when the average registration deviation amounts in the conveying direction (arrow F, Y-axis direction) of the first color registration marks 1a, 1e, 1i, 1m in the cardboard sheet 3 are sy1a, sy1e, sy1i, sy1m, respectively. The registration deviation amount Wy in the conveyance direction (arrow F, Y-axis direction) is

Wy = (sy1a + sy1e + sy1i + sy1m) / 4. Similarly, the average registration deviation amount Px in the width direction (X-axis direction) of the registration marks 1b, 1f, 1j, and 1n of the second color, the registration deviation amount Py in the conveyance direction (arrow F, Y-axis direction), and the third color Average registration deviation amount Rx in the width direction (X-axis direction) of registration marks 1c, 1g, 1p, and 1o, registration deviation amount Ry in the conveyance direction (arrow F, Y-axis direction), and fourth color registration marks 1d and 1h , 1l, and 1p in the width direction (X-axis direction) and an average registration deviation amount Bx in the transport direction (arrow F, Y-axis direction) are calculated.

  The calculation unit 16 uses the registration deviation amounts Wx, Px, Rx, Bx in the width direction (X-axis direction) of the registration marks of the respective colors and the registration deviation amounts Wy, Wy, in the conveyance direction (arrows F, Y-axis direction) of the registration marks of the respective colors. When Py, Ry, and By are calculated, it is determined whether the misregistration amounts Wx, Px, Rx, Bx, Wy, Py, Ry, and By are within a predetermined allowable range.

When the misregistration amounts Wx, Px, Rx, Bx, Wy, Py, Ry, and By are outside the predetermined allowable value range, data related to the misregistration amount is displayed on the display unit 19. Based on the transmitted misregistration amount data, the printing machine 100 prints in two-dimensional directions on the XY axis. Position adjustment is performed.
<Color density shift detection>

  Next, the quality inspection device 50 compares the data obtained by optically reading the register mark 1 of the printed cardboard sheet 3 with the CCD camera 13 and the plate (design) data to detect a color density shift. The detection of the color density deviation is performed for each registration mark 1 of each color, and in the present embodiment, the first color, the second color, the third color, and the fourth color, which are printing colors used for the corrugated cardboard sheet 3, are detected. This is done for each registration mark 1 of the ink.

  First, the detection unit 17 detects a predetermined reference color density level of the registration mark 1 to be printed on the cardboard sheet 3 based on the plate data of the registration mark input from the input unit 19 or the communication unit 18. The reference color density level is stored in the storage unit 12. The detection unit 17 detects the color density level of the register mark 1 printed on the cardboard sheet 3 based on the image data obtained by imaging with the CCD camera 13.

  Next, the calculation unit 16 compares the color density level of the register mark 1 with the reference color density level to calculate a color density level shift. As a method for comparing the color density level, the area image of the plate data and the area image of the image data of the register mark 1 are divided into regions of a predetermined size, and the color density levels of the corresponding divided images are compared. Alternatively, when the resolutions of the images of the image data to be compared are the same, the color density levels may be compared for each corresponding pixel. It can also be detected by other known methods.

  Next, it is determined whether or not the color density level deviation is within a predetermined allowable range. In the case of the present embodiment shown in FIG. 3, an example of four register marks (1a to 1p) corresponding to four colors is shown on the cardboard sheet 3, but a plurality of register marks 1 of the same color are printed. In this case, the color density level of the register mark 1 is averaged or corrected for each color, and it is determined whether or not the average color density level is within a predetermined allowable value range. Specifically, the first color of the first color is determined by averaging the color density levels of the registration marks 1a, 1e, 1i, and 1m. The second color and the second color are determined by averaging the color density levels of the register marks 1b, 1f, 1j, and 1n. The third color and the third color are determined by averaging the color density levels of the register marks 1c, 1g, 1P, and 1o. The fourth color and the fourth color are determined by averaging the color density levels of the register marks 1d, 1h, 1l, and 1p.

  The display unit 19 serving as an output unit displays data relating to the color density level deviation on the printing press 100 when the color density level deviation is not within a predetermined allowable value range.

  When the communication unit 18 determines that the color density level deviation is not within a predetermined allowable value range, the communication unit 18 sends the data relating to the color density level deviation to the printing unit 21 corresponding to each color of the printing machine 100. Send to any of 22, 23, 24.

In this embodiment, the registration inspection and the color density level deviation inspection can be performed accurately and simultaneously in the printing of corrugated cardboard sheets that are likely to be distorted such as stretch, shrinkage, warpage, and sinking. Efficiency can be further improved.
<Cardboard sheet inspection procedure>

  FIG. 6 is a flowchart illustrating a procedure in which the quality inspection apparatus 50 performs registration misregistration detection and color density detection of one cardboard sheet. When the quality inspection apparatus 50 receives an instruction to inspect the quality of the corrugated cardboard sheet 3 and transmits the instruction to the control unit 11, the process proceeds to step S1. In step S1, the register mark plate data is input from the input unit 19 or the communication unit 18, and the process proceeds to step S2.

  In step S <b> 2, the detection unit 17 detects a relative position with respect to a predetermined position on the register mark to be printed on the cardboard sheet 3 as a reference value based on the plate data and the dimension data of the cardboard sheet 3.

  In step S3, the printing surface of the traveling cardboard sheet 3 is imaged by the CCD camera 13, and image data is acquired.

  In step S4, the detection unit 17 detects the position of the center of gravity of the printed registration mark 1 based on the image data.

  In step S <b> 5, the calculation unit 17 calculates the misregistration amount and determines whether or not it is within a predetermined allowable value range. If the value is within the allowable value range, the process proceeds to step S7. If the value is not within the allowable value range, the process proceeds to step S6.

  In step S <b> 6, data relating to the misregistration amount and a warning that the value is not within the allowable value range are displayed on the display unit 19. Further, the data relating to the misregistration amount may be transmitted from the communication unit 18 to the printing press 100 and directly fed back to the printing press 100, or the data relating to the misregistration amount may be sent to the management computer in the production management system. However, the printing press may be controlled. Further, warning means for warning by voice, lamp, buzzer or the like may be further provided so that a warning is given when the deviation of the registration amount color density level is not within a predetermined allowable value range.

  In step S <b> 7, the detection unit 17 detects the color density level of the registration mark 1 printed on the cardboard sheet 3 based on the image data obtained by imaging with the CCD camera 13.

  In step S8, the calculation unit 16 compares the color density level of the register mark 1 with the reference color density level to calculate the color density level deviation, and the color density level deviation is within a predetermined allowable range. It is determined whether or not there is. If the value is not within the allowable value range, the process proceeds to step S6. If the value is within the allowable value range, the process ends.

  If the same version data is used repeatedly, the process may be executed from step S3. Further, although the present embodiment is intended for calculation of the misregistration amount in the trial printing, the present processing is executed as an arbitrary misregistration inspection, or for the purpose of monitoring the misregistration in the final printing, the steps after S3. This process may be repeatedly executed. In particular, it is possible to monitor the ink density in the printing press by repeatedly executing the color density level deviation inspection in the main printing.

  In the present embodiment, when the misregistration amounts Wx, Px, Rx, Bx, Wy, Py, Ry, and By are outside the predetermined allowable range, data relating to the misregistration amount is displayed on the display unit 19. The Based on the displayed data, the printing units 21, 22, 23, and 24 corresponding to the respective colors of the printing press 100 adjust the printing positions in the XY axis two-dimensional directions.

According to the quality inspection apparatus 50 of the present invention, it is possible to accurately detect misregistration even in the printing of corrugated cardboard sheets that are likely to be distorted such as stretch, shrinkage, warpage, and sinking. In addition, when the misregistration amount or the color density level deviation is not within a predetermined allowable range, the data relating to the misregistration amount or the data relating to the color density level deviation is output. Thus, it is possible to feed back data relating to the amount of misregistration or data relating to color density level deviation.
<Modification>

  As mentioned above, although embodiment of this invention was described, this invention is not limited to the thing of the content demonstrated above.

  In the present embodiment, the registration deviation amount is calculated by detecting the reference value with the predetermined position on the edge of the corrugated cardboard sheet 3 as the corner O1, and further, the position other than the corner O1 (for example, the corner O2) is calculated. Or the relative position with respect to the center of gravity of the corrugated cardboard sheet 3 or a point on the edge of the corrugated cardboard sheet) as a reference value, and calculates the misregistration amount of each register mark based on a plurality of reference values. It may be determined whether the amount of misregistration is within a predetermined allowable range.

  Further, when calculating the average registration deviation amount in the width direction (X-axis direction) of the corrugated cardboard sheet 3 or the average registration deviation amount in the conveyance direction (arrow F, Y-axis direction), the largest one is determined. Alternatively, the value of the registration mark having a deviation amount equal to or larger than the standard deviation may be regarded as the average registration deviation amount and the average registration deviation amount may be reduced. Further, depending on the state of ups and downs of the corrugated cardboard sheet, the deviation amount of each registration mark may be multiplied by a predetermined coefficient and then averaged to be regarded as the average registration deviation amount.

Further, the average registration deviation amount in the conveyance direction of the cardboard sheet 3 and the average registration deviation amount in the width direction of the cardboard sheet 3 orthogonal to the conveyance direction are calculated for all the plurality of registration marks 1 printed on the cardboard sheet 3. Then, the amount of deviation in printing may be used. Specifically, the registration deviation in the case of the corrugated cardboard sheet 3 in which four register marks 1 are printed at each of the four corners of the corrugated cardboard sheet 3 shown in FIG. 3 is the width direction of the corrugated cardboard sheet 3 of the register marks 1a to 1p ( When the registration deviation amounts in the X-axis direction) are sx1a, sx1b, sx1c,... Sx1p, the average registration deviation amount Sx in the width direction (X-axis direction) of the cardboard sheet 3 is
Sx = (sx1a + sx1b + sx1c,... + Sx1p) ÷ 16. On the other hand, if the registration deviation amounts of the registration marks 1a to 1p in the conveyance direction (arrow F, Y-axis direction) of the cardboard sheet 3 are sy1a, sy1b, sy1c,... Sy1p, respectively, the conveyance direction of the cardboard sheet 3 (arrow F) , Y-axis direction) average registration deviation amount Sy is
Sy = (sy1a + sy1b + sy1c,... + Sy1p) ÷ 16.
Then, it may be determined whether Sx and Sy are within a predetermined allowable range.

  Further, the present invention can accurately detect misregistration even when performing double-sided printing of corrugated cardboard sheets.

  Further, the reference value or the registration mark relative position may be corrected in advance in consideration of the positional deviation of the corrugated cardboard sheet that occurs when the corrugated cardboard sheet is fed to the printing apparatus 100 by a sheet feeding unit (not shown). For example, the correction of the reference value is performed by measuring the amount of misregistration of the corrugated cardboard sheet based on the center line in the captured image of the CCD camera 13 or the center line in the slotter of the box-making machine line (not shown), and based on this misalignment amount. It can be corrected.

  Further, when the size of the corrugated cardboard sheet varies due to expansion, contraction, warpage, sinking, or the like generated in the corrugated cardboard sheet 3, the standard is based on the standard dimensions of the corrugated cardboard sheet 3 stored in the storage unit 12 in advance. The misregistration amount may be calculated by correcting the value. Specifically, the detection unit 17 detects the positions of the edges or corners of the corrugated cardboard sheet 3 </ b> A that is actually printed from the image data and varies in size, and the calculation unit 16 detects the cardboard detected by the detection unit 17. The size of the printed cardboard sheet 3A is calculated from the positions of the edges or corners of the sheet 3A. Then, the registration deviation amount may be calculated by correcting the reference value based on the deviation amount between the dimension of the corrugated cardboard sheet 3A and the reference dimension.

  FIG. 7 is a diagram illustrating an example when shrinkage occurs in the conveyance direction and the width direction of the cardboard sheet. FIG. 7A shows the corrugated cardboard sheet 3 (corner portions O1, O2, O3, O4) having a reference dimension, and FIG. 7B shows the corrugated cardboard sheet 3 (corner portion) when shrinkage occurs in the conveyance direction and the width direction. It is the figure which showed roughly O5, O6, O7, O8). For example, with respect to the reference value in the conveyance direction of the corrugated cardboard sheet, the distance between the corner O1 (0, 0) and the corner O3 (xO3, yO3), the corner O5 (xO3, yO3) and the corner O7 (xO3) The shrinkage is obtained by comparing the distance between yO3), and the distance between corner O2 (xO2, yO2) and corner O4 (xO4, yO4), corner O6 (xO6, yO6) and corner The contraction rate is obtained by comparing the distance between O8 (xO8, yO8). A value obtained by multiplying the average value of the shrinkage ratios of the two by the reference value in the conveyance direction of the cardboard sheet may be used as a corrected reference value in the conveyance direction. Similarly, for the reference value in the width direction of the corrugated cardboard sheet, the distance between the corner O1 (0, 0) and the corner O2 (xO2, yO2), the corner O5 (xO5, yO5), and the corner O6 ( xO6, yO6) and the distance between the corners O3 (xO3, yO3) and the corners O4 (xO4, yO4) and the corners O7 (xO7, yO7) and The contraction rate is obtained by comparing the distance between the corners O8 (xO8, yO8). A value obtained by multiplying the average value of the shrinkage rates of the two by the reference value in the width direction of the cardboard sheet may be used as a corrected reference value in the width direction. According to this modification, even when the size of the corrugated cardboard sheet is fluctuated due to expansion, contraction, warpage, sinking, or the like, it is possible to reduce an error in the amount of misregistration.

  Moreover, you may determine the quality of the image printed on the cardboard sheet using the image which imaged the whole surface of the cardboard sheet. Specifically, the storage unit 12 stores plate data serving as a reference image to be printed on the cardboard sheet. Then, the detection unit detects an image printed on the cardboard sheet based on the image data obtained by being imaged by the imaging unit, and the calculation unit 16 prints the cardboard sheet detected by the detection unit 17 The quality is determined by comparing the image thus obtained with the reference image stored in the storage unit 12.

  FIG. 8 is a flowchart illustrating a procedure in which the quality inspection apparatus 50 performs registration misregistration detection, color density detection, and quality determination of an image printed on the cardboard sheet. When the quality inspection apparatus 50 receives an instruction to inspect the quality of the corrugated cardboard sheet 3 and transmits the instruction to the control unit 11, the process proceeds to step T1. Note that Steps T1 to T8 in FIG. 9 correspond to Steps S1 to S8 in FIG.

  In step T <b> 9, the quality is determined by comparing the image printed on the cardboard sheet 3 with the reference image stored in the storage unit 12. First, the detection unit 17 detects an image printed on the cardboard sheet 3 based on image data obtained by imaging the entire surface of the cardboard sheet 3 with the CCD camera 13.

  Further, the storage unit 12 stores, as a reference value, data relating to colors such as the position, shape, color tone, and color density of the reference image pattern to be printed on the cardboard sheet from the input plate data. The unit 16 determines the quality of the printed image by comparing the position, shape, color, and the like of the image detected by the detection unit 17 with a reference value. For example, the calculation unit 16 compares the image printed on the corrugated cardboard sheet detected by the detection unit 17 with the reference image stored in the storage unit 12, overlapping characters, missing lines, misalignment, image Pass / fail, image size change (change in aspect ratio), color tone, shape shift, and other items. If the value is within the allowable value range, the process ends as a non-defective product, and is determined as a defective product that is not within the allowable value range, and the process proceeds to step T10.

  In step T10, a warning that the printed image is not good is displayed on the display unit 19. Further, data related to items not within the allowable range may be displayed on the display unit 19, or data related to items not within the allowable range may be transmitted from the communication unit 18 to the printing press 100 and directly fed back to the printing press 100. . Further, a warning means for warning by voice, lamp, buzzer or the like may be further provided so that a warning is given when the printed image is not good. In addition to the plate data, the reference image may be obtained from non-defective printed data that has already been printed.

  In this modified example, the design of the image printed on the cardboard sheet can be inspected together with the misregistration inspection, so the quality and speed of the quality inspection of the printed cardboard sheet can be improved. It becomes.

  Note that the configurations described in the above embodiments and modifications may be replaced as appropriate as long as no contradiction arises. These modifications can also achieve the same effects as in the above embodiment.

DESCRIPTION OF SYMBOLS 1 Registration mark 3 Corrugated cardboard sheet 11 Control part 12 Storage part 13 CCD camera 14 Illumination part 15 Input part 16 Calculation part 17 Detection part 18 Communication part 19 Input part 21, 22, 23, 24 Printing unit 50 Quality inspection apparatus 100 Printing machine

Claims (8)

Storage means for storing a relative position with respect to a predetermined position of the cardboard sheet as a reference value for a predetermined position on the registration mark to be printed on the cardboard sheet;
Imaging means for imaging the printing surface of the cardboard sheet on which the registration mark is printed;
Illuminating means for illuminating a region imaged by the imaging means;
Detection that detects a relative position of the register mark printed on the corrugated cardboard sheet as a register mark relative position with respect to a predetermined position of the register card sheet, based on image data obtained by imaging by the imaging means Means,
By comparing the relative position of the registration mark detected by the detection means and the reference value stored in the storage means, the amount of registration deviation along the conveyance direction of the cardboard sheet and the orthogonal to the conveyance direction A calculation means for calculating a misregistration amount along the width direction of the cardboard sheet;
A cardboard sheet quality inspection apparatus comprising: The arithmetic means determines whether the misregistration amount is within a predetermined tolerance range;
The cardboard sheet quality inspection device according to claim 1, further comprising: an output unit that outputs data relating to the misregistration amount when the misregistration amount is not within a predetermined allowable range. For the predetermined positions on the plurality of registration marks to be printed at positions at both ends with respect to at least the transport direction of the corrugated cardboard sheet, the storage means uses a relative position with respect to the predetermined position of the corrugated cardboard sheet as a reference value. Remember,
The arithmetic means compares the registration mark relative positions of the plurality of registration marks detected by the detection means with the corresponding reference values, and the average registration deviation in the conveyance direction of the cardboard sheet at the plurality of registration marks. An average registration deviation amount in the width direction of the corrugated cardboard sheet perpendicular to the conveyance direction is calculated, and it is determined whether or not the average registration deviation quantity is within a predetermined allowable range. 2. The cardboard sheet quality inspection apparatus according to 2. The storage means stores a reference dimension of the cardboard sheet,
The detection means detects the position of the corner of the cardboard sheet from the image data;
The calculation means calculates the size of the printed cardboard sheet from the position of the corner of the cardboard sheet detected by the detection means, and the reference value based on the amount of deviation between the dimension of the cardboard sheet and the reference dimension The cardboard sheet quality inspection device according to claim 1, wherein the registration deviation amount is calculated by correcting the misregistration. The storage means stores a predetermined reference color density level of a register mark to be printed on the cardboard sheet;
The detection means detects a color density level of the register mark printed on the cardboard sheet based on image data obtained by being imaged by the imaging means,
The arithmetic means calculates a color density level deviation by comparing a color density level of the register mark with a reference color density level, and whether the color density level deviation is within a predetermined allowable range. Determine whether or not
The corrugated cardboard sheet according to any one of claims 2 to 4, wherein the output means outputs data relating to the shift in the color density level when the shift in the color density level is not within a predetermined allowable range. Quality inspection device.   The cardboard sheet quality inspection device according to claim 2, wherein the imaging unit images the entire surface of the cardboard sheet. The storage means stores a reference image to be printed on the cardboard sheet;
The detection means detects an image printed on the cardboard sheet based on image data obtained by being imaged by the imaging means,
The quality of the corrugated board sheet according to claim 6, wherein the arithmetic means judges the quality by comparing an image printed on the cardboard sheet detected by the detecting means with a reference image stored in the storage means. Inspection device. Storing a relative position of the cardboard sheet relative to the predetermined position as a reference value for a predetermined position on the registration mark to be printed on the cardboard sheet;
An imaging step of imaging the cardboard sheet on which the registration mark is printed;
Detection that detects a relative position of the register mark printed on the corrugated cardboard sheet as a register mark relative position with respect to a predetermined position of the corrugated cardboard sheet based on image data obtained by imaging in the imaging step Process,
By comparing the relative position of the registration mark detected by the detection step with the reference value stored in the storage means, the registration deviation amount along the conveyance direction of the cardboard sheet and the orthogonal to the conveyance direction A calculation step of calculating the amount of misregistration along the width direction of the cardboard sheet, and determining whether the amount of misregistration is within a predetermined tolerance range;
A cardboard sheet quality inspection method comprising:

Images