JP2014038012A - Inspection method of flat paper folding and flat paper folding inspection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inspection method of flat paper folding capable of precisely inspecting for any folding existing in a flat paper in a lamination of plural flat papers.SOLUTION: A flat paper lamination plane of a lamination item is illuminated with illumination light from an illuminating device disposed at both sides of the lamination item from a side thereof at an angle. Imaging apparatuses disposed at both sides of the lamination item take images of the flat paper lamination plane. Pixels for performing inspection are set in order from an edge of the image obtained by the imaging apparatus. Average brightness calculation area for calculating average brightness ambient of the set pixels is set at the top and the bottom of the inspection pixel. Dark point detection areas are set at right and left sides of the inspection pixel. A brightness difference between the brightness of the inspection pixel and the average brightness in the average brightness calculation area is compared with a first reference value. The brightness difference between the average brightness in the average brightness calculation area and the minimum brightness in the dark point detection area is compared with a second reference value to inspect for any folding.

Description

  INDUSTRIAL APPLICABILITY The present invention is a flat paper folding inspection method for inspecting whether or not there is a folding of a flat paper in a laminate composed of a large number of flat papers cut to a certain size, and is used in the method. The present invention relates to a flat paper folding inspection apparatus.

  In general, in a paper factory that manufactures printing paper, information paper, etc., when shipping flat paper obtained by cutting a rolled paper into a predetermined size as a product, a laminate made up of a large number of flat paper is used as a conveyor. The laminate is then transported to a packaging machine, and the laminate transported to the packaging machine is packaged with wrapping paper or packaging film before being shipped. In this case, if the folding of the flat paper as shown in FIG. 5 occurs in the laminate, it causes a paper feed failure or a defective printing product in a printing machine or a copying machine. It is necessary to inspect whether or not there is any folding of the flat paper in the laminate formed by laminating.

Conventionally, a method for inspecting the folding of the flat paper has been adopted in which an inspector visually checks the flat paper laminated surface of the laminate to determine whether or not the paper is folded. In this case, when the number of laminated flat paper sheets is several hundred or more, the folded portion of the flat paper is crushed by the weight of the flat paper laminated thereon, and the folding of the flat paper is visually recognized. This makes it difficult to overlook.
In Patent Literature 1, after a sheet folded in half by a chopper folding machine or the like is conveyed in a scaled state, the end surface portion of the sheet is imaged by a CCD camera to obtain a brightness distribution image of the end surface portion of the sheet. In addition, a technique is described in which a divided lightness distribution image obtained by dividing a lightness distribution image in the sheet stacking direction (vertical direction) is analyzed to detect sheet corner breakage or breakage.

Japanese Patent No. 3834692

According to the technique described in Patent Document 1, it is possible to detect a corner break of a sheet conveyed in a scaled state, but the thickness of the sheet in the height direction when the folded surface of the sheet is viewed from the camera side. Must be sufficiently larger and have a certain area. For this reason, when the number of flat paper sheets is several hundred or more, even if the technique described in Patent Document 1 is applied to the flat paper folding inspection, the folding of the flat paper cannot be detected. there is a possibility.
The present invention has been made in view of the above-described problems, and can be used to accurately inspect whether or not a flat paper fold is present in a laminate composed of a large number of flat papers. An object of the present invention is to provide a paper folding inspection method and a flat paper folding inspection apparatus.

  In order to solve the above-mentioned problems, the invention of claim 1 is a method for inspecting whether or not there is a fold of the flat paper in a laminate formed by laminating flat paper cut to a certain size. And illuminating illumination light obliquely from the lateral direction of the laminate from a plurality of illumination devices arranged on both sides of the laminate, and arranged on both sides of the laminate. The plurality of imaging devices captures the flat paper laminated surface of the laminate, sets pixels to be inspected in order from the edge of the flat paper laminated surface image picked up by the imaging device, and surrounds the set pixels An average luminance calculation area for calculating the average luminance of the image is set on the upper side and the lower side of the pixel to be inspected, and a dark portion detection area for detecting a dark portion caused by the folding of the flat paper is set in the inspection. Set the folds on the left and right sides of the pixel Characterized in that it checks for.

According to a second aspect of the present invention, in the flat paper folding inspection method according to the first aspect, the luminance difference between the luminance of the pixel to be inspected and the average luminance of the average luminance calculation area is defined as a first reference value. In addition, the difference between the average luminance of the average luminance calculation area and the minimum luminance of the dark portion detection area is compared with a second reference value to check for the presence or absence of the folding.
According to a third aspect of the present invention, in the flat paper folding inspection method according to the second aspect, the luminance of the pixel to be inspected and the average luminance calculation area set above or below the pixel to be inspected The luminance difference from the average luminance is larger than the first reference value, and the average luminance of the average luminance calculation area set above or below the pixel to be inspected is set to the left or right side of the pixel to be inspected. When the difference in brightness from the lowest brightness of the dark area detection area is larger than the second reference value, it is determined that there is a folding of flat paper in the laminate.

According to a fourth aspect of the present invention, there is provided the flat paper folding inspection method according to any one of the first to third aspects, wherein illumination light is emitted from the illumination device to the flat paper laminated surface of the laminate. Irradiation from the lateral direction of the laminate is performed at an irradiation angle of 30 ° to 75 ° with respect to the paper lamination surface.
According to a fifth aspect of the present invention, in the flat paper folding inspection method according to the fourth aspect, when the illumination angle of the illumination light is α and the imaging angle of the imaging device is β, α + 15 ° ≦ β ≦ 90. The flat paper laminated surface of the laminate is imaged by the imaging device under a condition that satisfies the above condition.

A sixth aspect of the invention is the flat paper folding inspection method according to any one of the first to fifth aspects, wherein the illumination light has directivity from the illumination device to the flat paper laminated surface of the laminate. It is characterized by irradiating.
The invention of claim 7 is an apparatus for inspecting whether or not the folding of the flat paper has occurred in the laminated product obtained by laminating the flat paper cut to a certain size, on both sides of the laminated product. A plurality of illumination devices that irradiate illumination light obliquely from the lateral direction of the laminate on the flat paper laminate surface, a plurality of imaging devices that image the flat paper laminate surfaces on both sides of the laminate, and the imaging device The pixels to be inspected are set as the pixels to be inspected in order from the edge of the image of the captured flat paper laminated surface, and the average luminance calculation area for calculating the average luminance of the flat paper laminated surface around the pixel to be inspected And an area setting means for setting a dark part detection area for detecting a dark part caused by folding of the flat paper on both the left and right sides of the pixel to be inspected. And

  According to an eighth aspect of the present invention, in the flat paper folding inspection apparatus according to the seventh aspect, the luminance difference between the luminance of the pixel to be inspected and the average luminance of the average luminance calculation area is compared with a first reference value. And comparing means for comparing a luminance difference between the average luminance of the average luminance calculation area and the minimum luminance of the dark portion detection area with a second reference value.

  According to the present invention, it is possible to detect the folding of the flat paper even when it is difficult to visually recognize the folded portion of the flat paper or when there is a step or undulation on the flat paper lamination surface of the laminate. Therefore, it is possible to accurately inspect whether or not there is any folding of the flat paper in the laminate composed of a large number of flat paper.

It is a figure which shows an example of the flat paper folding inspection apparatus used when implementing this invention. It is a figure for demonstrating the case where the folding of a flat paper is test | inspected using the flat paper folding inspection apparatus shown in FIG. It is a figure which shows the other example of the flat paper folding inspection apparatus used when implementing this invention. It is a figure for demonstrating the case where the folding of a flat paper is test | inspected using the flat paper folding inspection apparatus shown in FIG. It is a figure which shows the kind of folding which generate | occur | produces when a flat paper is laminated | stacked. It is a figure for demonstrating the case where illumination light is irradiated with the irradiation angle of 30 degrees-70 degrees on the flat paper lamination surface of a laminated body. It is a figure which shows the processing flow of the image data processed by CPU of a flat paper folding inspection apparatus. It is a figure which shows an example of the average brightness | luminance calculation area and dark part detection area which are set by CPU of a flat paper folding inspection apparatus.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a diagram showing an example of a flat paper folding inspection apparatus used when carrying out the present invention. The flat paper folding inspection apparatus shown in FIG. 1 inspects whether or not there is any folding of a flat paper in a laminate 2 made up of a large number of flat papers 1 and includes a laminate transport mechanism. 3, illumination devices 41, 42, 43, 44, imaging devices 51, 52, imaging angle adjustment mechanisms 61, 62, imaging device moving mechanisms 71, 72, width direction driving mechanisms 91, 92, and image processing device 10. .

The laminate transport mechanism 3 transports the laminate 2 and is composed of, for example, a roller conveyor.
The illuminating devices 41 to 44 irradiate the flat paper laminated surface 2a of the laminate 2 with illumination light from the lateral direction of the laminate 2, and have an angle of 30 ° to 75 ° with respect to the flat paper laminated surface 2a. 2 are arranged on each side of the laminate 2 so as to be irradiated with illumination light. In addition, it is preferable to use what can emit the light which has directivity (for example, LED etc.) as a light source of the illuminating devices 41-44.

The imaging devices 51 and 52 image the flat paper laminated surface 2a of the laminate 2, and are arranged on both sides of the laminate 2 so as to satisfy the following expression (1). The imaging devices 51 and 52 have a plurality of (six in the present embodiment shown in FIG. 1B) CCD cameras 11, and these CCD cameras 11 are arranged at almost equal intervals in the height direction of the laminate 2. The flat paper laminated surface 2a of the laminate 2 is arranged so as to be imaged.
α + 15 ° ≦ β ≦ 90 ° (1)
Where α is the irradiation angle of the illumination light with respect to the flat paper laminated surface, and β is the imaging angle of the imaging device with respect to the flat paper laminated surface. Moreover, the definition of each angle is shown in FIG.6 (b).

The imaging angle adjustment mechanisms 61 and 62 adjust the imaging angle β of the imaging devices 51 and 52, and are arranged on both sides of the laminate 2 as with the imaging devices 51 and 52.
The imaging device moving mechanisms 71 and 72 horizontally move the illuminating devices 41 to 44, the imaging devices 51 and 52, and the imaging angle adjustment mechanisms 61 and 62 in parallel with the flat paper laminated surface 2a of the laminate 2, for example, It is composed of a ball screw that feeds and drives the slider in the left-right direction, a ball screw drive motor that drives the ball screw, and the like.

The width direction driving mechanisms 91 and 92 drive the illumination devices 41 to 44, the imaging devices 51 and 52, the imaging angle adjustment mechanisms 61 and 62, and the imaging device moving mechanisms 71 and 72 in the width direction of the laminate 2. , Disposed on both sides of the laminate 2.
The image processing apparatus 10 processes an image of the flat sheet laminated surface 2a picked up by the image pickup apparatuses 51 and 52. For example, the A / D converter 12, the storage device 13, a central processing unit (hereinafter referred to as CPU) 14) etc.

  FIG. 2 is a diagram for explaining the case of inspecting the folding of the flat paper using the flat paper folding inspection apparatus shown in FIG. 1, and moving the image pickup apparatus and the illumination apparatus by stopping the laminate. It is an example of the apparatus which extract | collects the image of the side surface whole range of a laminated body by. When the above-described flat paper folding inspection apparatus inspects the folding of the flat paper, as shown in FIG. Irradiated illumination light (for example, LED illumination light) is irradiated onto the flat paper laminated surface 2a. At the same time, the image pickup devices 51 and 52, the image pickup angle adjustment mechanisms 61 and 62, and the illumination devices 41 and 42 are moved in the direction indicated by the arrow A by the image pickup device moving mechanisms 71 and 72, and the flat paper of the laminate 2 is used. The laminated surface 2 a is imaged by the imaging devices 51 and 52.

  If an image is taken from one end of the flat paper laminate surface 2a to the other end, then the flat paper laminate surface of the laminate 2 from the lighting devices 43 and 44 as shown in FIG. 2a is irradiated with illumination light, and the orientations of the imaging devices 51 and 52 are changed by the imaging angle adjustment mechanisms 61 and 62 so that the angle of the illumination devices 43 and 44 becomes β shown in the equation (1). Thereafter, the planer paper stacking surface 2a of the laminate 2 is moved by the imaging devices 51 and 52 to the planographic paper stacking surface 2a while moving the image pickup device moving mechanisms 71 and 72 in the direction indicated by the arrow A ′ opposite to the arrow A. Folding is inspected by imaging from the other end to one end.

  FIG. 3 shows another example of a flat paper folding inspection apparatus used when carrying out the present invention. The flat paper folding inspection apparatus shown in FIG. 3 includes a laminate transport mechanism 3, an illumination device 41, 42, 43, 44, imaging devices 51, 52, 53, 54, elevating mechanisms 81, 82, width direction driving mechanisms 91, 92, and the image processing device 10. In this example, the image collection in the conveyor flow direction of the laminate is performed by moving the conveyor side and pitch-feeding the laminate.

The imaging devices 51 to 54 image the flat paper laminated surface 2a of the laminate 2 and are arranged two on each side of the laminate 2 so as to satisfy the formula (1).
The elevating mechanisms 81 and 82 drive the lighting devices 41 to 44 and the imaging devices 51 to 54 up and down. For example, a ball screw that feeds and drives the slider in the up and down direction, and a ball screw drive that drives the ball screw. It consists of a motor and the like.
The width direction driving mechanisms 91 and 92 drive the illumination devices 41 to 44, the imaging devices 51 to 54, and the elevating mechanisms 81 and 82 in the width direction of the laminate 2, and are disposed on both sides of the laminate 2. .

The image processing apparatus 10 processes an image of the flat sheet laminated surface 2a picked up by the image pickup apparatuses 51 to 54. Like the one shown in FIG. 1, the A / D converter 12 and the storage device 13 are used. CPU 14 and the like.
FIG. 4 is a diagram for explaining the case where the flat paper folding inspection apparatus shown in FIG. 3 is used to inspect the folding of the flat paper. 4A, for example, as shown in FIG. 4A, illumination light having directivity from the illumination devices 41 and 42 to the flat paper laminated surface 2a of the laminate 2 among the illumination devices 41 to 44, for example. (For example, LED illumination light) is irradiated. At the same time, the image pickup devices 51 and 52 image the flat paper laminated surface 2 a of the laminate 2 while lowering the elevating mechanisms 81 and 82.

Next, when the lifting mechanisms 81 and 82 are lowered to the lower end, as shown in FIG. 4B, the lighting devices 41 and 42 are turned off, the lighting devices 43 and 44 are turned on, and the lifting mechanisms 81 and 82 are raised. Then, the image pickup devices 53 and 54 image the flat paper laminated surface 2a of the laminate 2.
When the elevating mechanisms 81 and 82 are raised to the upper end, the illumination devices 43 and 44 are turned off, and the imaging of the imaging devices 53 and 54 is finished. Thereafter, as shown in FIG. 4C, the laminate 2 is conveyed by the laminate conveyance mechanism 3 in the direction indicated by the arrow A by the visual field width of the imaging device. Then, the elevating mechanisms 81 and 82 are moved up and down again to perform imaging similar to that shown in FIGS. 4 (a) and 4 (b).

  FIG. 6 is a diagram for explaining a case where illumination light is irradiated at an irradiation angle of 30 ° to 70 ° on the flat paper laminated surface of the laminate. As in the present embodiment, illumination light is irradiated onto the flat paper laminate surface 2a of the laminate 2 from the lateral direction of the laminate 2 at an irradiation angle α of 30 ° to 70 °, and the imaging angle β of the imaging device is α + 15. When the flat paper laminated surface 2a of the laminate 2 is imaged with the setting of ° ≦ β ≦ 90 °, if there is a fold in the flat paper in the laminate 2, as shown in FIG. Of the illumination light irradiated onto the flat paper laminate surface 2a, the illumination light regularly reflected at the folding point 1b of the folded portion 1a of the flat paper 1 on the flat paper laminate surface 2a is image pickup devices 51, 52 ( Or the reflected light Lr1 incident on one of 51 to 54). On the other hand, in the normal part where there is no folding, the illumination light specularly reflected by the flat paper laminated surface 2a of the laminate 2 becomes reflected light Lr2 that is not incident on any of the imaging devices 51 and 52 (or 51 to 54). The light incident on the imaging devices 51 and 52 (or 51 to 54) is only the illumination light irregularly reflected by the flat paper laminated surface 2a.

  The illumination light Lr3 shown in FIG. 6 enters the gap generated by the folding, and the reflected light cannot be captured by the imaging devices 51 and 52 (or 51 to 54). Lr3 is an imaging device compared to Lr1 and Lr2. When captured, the image appears dark. Therefore, when there is a fold in the flat paper laminated surface 2a, dark (Lr3) -bright (Lr1) exists in a pair in that portion. By searching for this dark-light pair, when the number of folded sheets of flat paper 1 is 1, or the height of the laminate 2 is as high as 1.5 m or more, Even when the folded portion of the paper 1 is crushed, it is possible to accurately inspect whether or not the flat paper 1 is folded in the laminate 2, so that the illumination angle of the illumination light and the imaging device The imaging angle was set to the above angle.

  FIG. 5 shows the types of folds that occur when flat papers are stacked, and the types of folds that occur when a large number of flat papers 1 are stacked include the positive direction shown in FIG. Folding includes a 90 ° bend A shown in FIG. 5 (b), a 90 ° bend B shown in FIG. 5 (c), and a reverse bend shown in FIG. 5 (d). In the measurement principle shown in FIG. 6, it is necessary to change the directions (directions) of the imaging device and the illumination device in FIGS. 5 (a) and 5 (b) and FIGS. 5 (c) and 5 (d). This is because Lr1 of FIG. 6 does not enter the imaging device when the orientation of the imaging device and the illumination device is the orientation shown in FIGS. 5A and 5B, and the 90 ° folding shown in FIGS. 5C and 5D is performed. This is because B and reverse folding cannot be detected. Therefore, when inspecting whether or not the folding shown in FIG. 5 exists in the laminate 2, the method shown in FIG. 2 is a state in which the orientation of the imaging device and the illumination device is the orientation shown in FIG. 2, the flat sheet laminated surface 2 a of the laminate 2 is imaged while moving the imaging device and the illumination device, and then the orientation of the imaging device and the illumination device is changed to the orientation shown in FIG. It is necessary to take an image of the paper laminate surface 2a again.

FIG. 7 is a diagram showing a processing flow of image data processed by the CPU 14 of the sheet folding inspection apparatus shown in FIGS. 1 and 3, and FIG. 8 shows an example of an average luminance calculation area and a dark part detection area set by the CPU 14. Hereinafter, the method for inspecting the folding of the flat paper according to the present invention will be described with reference to FIGS. 7 and 8. FIG.
When the flat paper laminated surface 2a of the laminate 2 is imaged by the imaging devices 51 and 52 shown in FIG. 1 or the imaging devices 51 to 54 shown in FIG. 3, an image signal is output from the imaging devices 51 and 52 (or 51 to 54). Is output. At this time, the image signals output from the imaging devices 51 and 52 (or 51 to 54) are converted into digital signals by the A / D converter 12, and then stored as image data of the flat paper laminated surface 2a. Stored in

  When the image data of the flat sheet laminated surface 2a is stored in the storage device 13, the CPU 14 of the image processing device 10 captures the image data stored in the storage device 13, and performs a folding test from the image data captured in step S1. Set the pixel to perform. This is set in order from the edge of the captured image. In the next step S2, average luminance calculation areas Y1 and Y2 as shown in FIG. 8 are set on the upper and lower sides of the pixel to be inspected.

The average luminance calculation areas Y1 and Y2 are areas for calculating the average luminance around the pixel to be inspected on the flat paper laminated surface 2a. The average luminance calculation areas Y1 and Y2 are set above and below the pixel to be inspected. If that, CPU 14 after calculating the average luminance of the average luminance calculation area Y1, Y2 in step S3, determined brightness difference [Delta] L _a of the following formula (2) and (3), the [Delta] L _B in step S4.
Luminance value of pixel to be inspected−average luminance in area Y1 = ΔL _A (2)
Luminance value of pixel to be inspected−average luminance in area Y2 = ΔL _B (3)

When the luminance differences ΔL _A and ΔL _B are calculated in step S4, the CPU 14 determines in steps S5 and S6 whether the luminance differences ΔL _A and ΔL _B are larger than the first reference value. As the first reference value, a luminance difference value obtained from data of a folded image obtained by prior apparatus adjustment is set. If the luminance differences ΔL _A and ΔL _B are equal to or smaller than the first reference value, the process proceeds to step S14, where the pixel to be inspected is recognized as not being a candidate for Lr1 brighter than the surrounding pixels, and the CPU 14 then proceeds to step S14. Proceed to S16. In step S16, it is confirmed whether or not the entire imaging range of the imaging apparatus has been inspected. If there is a remaining area, in step S17, the pixel to be inspected for Lr1 is moved one by one, and the determination process is performed again. All the captured areas are inspected. In the case where a plurality of image pickup devices are installed, if Lr1 does not exist within the field of view of all the image pickup devices, it is determined that Lr1 does not exist in the entire area of the flat paper laminated surface 2a. The fact that the folding of the flat paper 1 does not exist in the laminate 2 is output to a display device (not shown). The luminance difference [Delta] L _A, if any of the [Delta] L _B is greater than the first reference value, CPU 14 proceeds to step S7, the dark portion detection area X1, X2, as shown in FIG. 8, the left and right sides of the pixel to be inspected Set.

The dark part detection areas X1 and X2 are areas for detecting dark parts (gap parts) caused by folding of the flat paper 1. When the dark part detection areas X1 and X2 are set on the left and right sides of the pixel to be inspected, After calculating the minimum luminance of the dark part detection areas X1 and X2 in step S8, the CPU 14 obtains luminance differences ΔL _C , ΔL _D , ΔL _E , and ΔL _F expressed by the following equations (4) to (7) in step S9. . Here, the reason for calculating the minimum luminance of the dark part detection areas X1 and X2 is that in the case where a large load is applied due to being stacked as high as flat paper, the folded part is crushed and the height of the dark part, This is because there is a case where the width becomes small, and it is difficult to produce a difference in average luminance (sensitivity is low).
Average luminance of area Y1−Minimum luminance of area X1 = ΔL _C (4)
Average luminance of area Y1−minimum luminance of area X2 = ΔL _D (5)
Average luminance of area Y2−minimum luminance of area X1 = ΔL _E (6)
Average luminance of area Y2−minimum luminance of area X2 = ΔL _F (7)

When the luminance differences ΔL _C , ΔL _D , ΔL _E , and ΔL _F are calculated in step S9, the CPU 14 determines whether the luminance differences ΔL _{C to} ΔL _F are larger than the second reference value in steps S10 to S13. . As the second reference value, a luminance difference value obtained from data of a folded image obtained by prior device adjustment is set. Here, when the luminance differences ΔL _{C to} ΔL _F are equal to or smaller than the second reference value, it is recognized in step S14 that the pixel to be inspected is not a candidate for Lr3 darker than the surrounding pixels, and then the CPU 14 proceeds to step S16. move on. In step S16, it is confirmed whether or not the entire imaging range of the imaging apparatus has been inspected. If there is a remaining area, the pixel to be inspected for the presence of Lr1 is moved one by one in step S17, and the determination process is performed again. Inspect the entire imaged area. In a case where a plurality of imaging devices are installed, if there is no Lr1-Lr3 pair in the field of view of all imaging devices, there is no Lr1-Lr3 pair in the range imaged by the imaging device. If there is no Lr1-Lr3 pair in the field of view of all the imaging devices, it is determined that there is no folding in the entire area of the flat paper laminated surface 2a, and the flat paper 1 is folded in step S18. The fact that no inclusions are present in the laminate 2 is output to a display device (not shown).

Also, recognize that any of the luminance difference ΔL _C ~ΔL _F is greater than the second reference value, Lr3 darker than surrounding pixels on the left and right of the pixel to be inspected (in step S5, S6 determines that Lr1 candidate) is present To do. The CPU 14 proceeds to step S15, recognizes that a bright (Lr1) -dark (Lr3) pair exists, and proceeds to step S16. In step S16, it is confirmed whether or not the entire imaging range of the imaging apparatus has been inspected. If there is a remaining area, the pixel to be inspected for the presence of Lr1 is moved one by one in step S17, and the determination process is performed again. Inspect the entire imaged area. In the case where a plurality of imaging devices are installed, the entire imaging region of all imaging devices is inspected, and if there is even one pair of Lr1-Lr3, a display device that does not show an inspection result indicating that there is a fold. Etc.

  When outputting the presence of folding to a display device or the like, the position within the plane paper laminated surface 2a is determined from the information on the position of the folding in the image (the position of the pixel of the pair of Lr1-Lr3). Converts to information and outputs the presence / absence of folding and position information. From this information, the operator confirms the fold and performs correction work.

  As described above, the illuminating devices 41 to 44 disposed on both sides of the laminate 2 irradiate the illuminating light having directivity to the flat paper laminate surface 2a of the laminate 2 obliquely from the lateral direction of the laminate 2. By imaging the flat paper laminated surface 2a of the laminate 2 with the imaging devices 51, 52 or 51 to 54 arranged on both sides of the laminate 2, the folded portion is brighter than the surroundings and the left and right sides are more than the surroundings. It becomes a characteristic state that the image becomes dark, and it becomes easy to recognize the fold from the image of the flat paper laminated surface 2a imaged by the imaging devices 51, 52 or 51-54. This has the effect of facilitating recognition because the folded portion becomes bright and conspicuous not only when the state is taken in by the camera but also during visual inspection. In this way, the folded portion is in a state where it can be easily recognized for photographing and visual observation by the camera, so that the folded portion of the flat paper 1 can be reliably recognized, and the folding of the flat paper 1 is accurately detected. It becomes possible to do.

Further, the average luminance calculation areas Y1 and Y2 for calculating the average luminance of the flat paper laminated surface 2a where the flat paper 1 is not folded are set above and below the pixel to be inspected, and the flat paper 1 Are set on the left and right sides of the pixel to be inspected, and a luminance difference ΔL between the luminance of the pixel to be inspected and the average luminance of the average luminance calculation areas Y1 and Y2 is set. _A and ΔL _B are compared with the first reference value, and luminance differences ΔL _C , ΔL _D , ΔL _E and ΔL _F between the average luminance of the average luminance calculation areas Y1 and Y2 and the lowest luminance of the dark area detection areas X1 and X2 are compared. Is compared with the second reference value, so that the comparison criteria are set in a double manner, with the determination criterion of folding being locally and vertically and horizontally. This produces the following advantages. That is, when the height of the laminate 2 is, for example, 1.8 m and the width is, for example, 1.3 m, it is very difficult to illuminate the entire flat paper laminate surface of the laminate 2 with uniform brightness. In particular, when the laminate 2 has undulations or steps, the arrangement relationship between the illumination, the side surface of the laminate (flat paper laminate surface), and the imaging device changes, and the brightness of the side of the laminate imaged by the imaging device changes. It changes depending on the swell and level difference.

  In this inspection method, the average luminance calculation area and the dark part detection area are set at a position of the nearest several millimeters of the inspection pixel, and a determination is made therein. As mentioned above, even if the brightness changes due to swell, etc., only a narrow range of several millimeters is seen in both the top and bottom and left and right directions (local), so that the illumination (brightness) is uniform within that range. Possible and stable inspection can be performed.

  In the case of a step, the brightness changes suddenly above and below the step. In this case, since the average luminance area is set above and below the inspection pixel, if the fold is above the step, If the fold is in the average luminance area and the fold is below the step, the fold can be detected in the lower average luminance area. Thus, even when there is a step or undulation on the flat paper laminated surface 2a of the laminate 2, it is possible to accurately detect the folding of the flat paper 1.

The illumination method of the present apparatus, Orekomi becomes brighter than the surrounding, to have a feature that becomes darker than the surrounding by lifting the left and right Orekomi, the luminance difference [Delta] L _A or the luminance difference [Delta] L _B greater than the first reference value In addition, when any of the luminance differences ΔL _C , ΔL _D , ΔL _E , and ΔL _F is greater than the second reference value, it is determined that there is a fold of the flat paper in the laminate 2, thereby It is possible to accurately inspect whether or not the flat paper 1 is folded in the laminate 2 made of the paper 1.

  Further, as in the present embodiment described above, only the regular reflection light Lr1 generated at the folded portion is observed by irradiating the illuminating light having directivity to the flat paper laminated surface 2a of the laminate 2. Rather than the dark (Lr3) -bright (Lr1) pair, it is possible to detect folding, which causes unevenness due to large paper dust adhesion or paper pain on the flat paper laminate surface. Even if bright spots and dark spots exist alone due to unevenness on the paper lamination surface, it is possible to accurately inspect the presence or absence of folding without being affected by adhesion of paper dust or paper pain. .

  In the embodiment of the present invention described above, an image processing apparatus that processes an image on a flat paper laminated surface has an A / D converter that converts an image signal output from an imaging apparatus into a digital signal. Although shown, it is not restricted to this, For example, you may make it digitize an image signal within an imaging device, and may output it to an image processing apparatus.

DESCRIPTION OF SYMBOLS 1 ... Flat paper 2 ... Laminate 2a ... Flat paper laminated surface 3 ... Laminate conveyance mechanism 41, 42, 43, 44 ... Illumination device 51, 52, 53, 54 ... Imaging device 61, 62 ... Imaging angle adjustment mechanism 71, 72 ... Imaging device moving mechanism 81, 82 ... Elevating mechanism 91, 92 ... Width direction driving mechanism 10 ... Image processing device 11 ... CCD camera 12 ... A / D converter 13 ... Storage device 14 ... Central processing unit (CPU) )
Y1, Y2 ... average luminance calculation area X1, X2 ... dark area detection area

Claims (8)

  A method for inspecting whether or not a flat paper fold is present in a laminate formed by laminating flat paper cut to a certain size, and a plurality of illumination devices arranged on both sides of the laminate The flat paper laminate surface of the laminate is irradiated with the illumination light obliquely from the lateral direction of the laminate, and the plurality of imaging devices arranged on both sides of the laminate. The pixels to be inspected are set in order from the edge of the image of the flat paper laminated surface imaged by the imaging device, and the average luminance calculation area for calculating the average luminance around the set pixels is set as the inspection. And the presence or absence of folds by setting dark area detection areas for detecting dark areas caused by folding of the flat paper on both the left and right sides of the pixels to be inspected. Folding flat paper, characterized by inspection Write inspection method.   The luminance difference between the luminance of the pixel to be inspected and the average luminance of the average luminance calculation area is compared with a first reference value, and the luminance between the average luminance of the average luminance calculation area and the minimum luminance of the dark portion detection area 2. The method for inspecting the folding of a flat paper according to claim 1, wherein the presence or absence of the folding is inspected by comparing the difference with a second reference value.   The luminance difference between the luminance of the pixel to be inspected and the average luminance of the average luminance calculation area set above or below the pixel to be inspected is larger than the first reference value, and When the luminance difference between the average luminance of the average luminance calculation area set on the upper side or the lower side and the lowest luminance of the dark area detection area set on the left or right side of the pixel to be inspected is larger than the second reference value The method for inspecting the folding of a flat paper according to claim 2, wherein it is determined that the folding of the flat paper is present in the laminate.   The illumination light is irradiated from the illumination device from the lateral direction of the laminate at an irradiation angle of 30 ° to 75 ° with respect to the flat paper laminate surface. Item 4. A method for inspecting folding of flat paper according to any one of Items 1 to 3.   When the illumination angle of the illumination light is α and the imaging angle of the imaging device is β, the flat paper laminated surface of the laminate is imaged by the imaging device under a condition that satisfies α + 15 ° ≦ β ≦ 90 °. The method for inspecting the folding of a flat paper according to claim 4.   6. The flat paper folding inspection method according to claim 1, wherein directing illumination light is irradiated from the lighting device to the flat paper laminated surface of the laminate.   An apparatus for inspecting whether or not a flat paper fold has occurred in a laminate formed by laminating flat paper cut to a certain size, and illuminating the flat paper laminated surfaces on both sides of the laminate A plurality of illumination devices that irradiate light obliquely from the lateral direction of the laminate, a plurality of imaging devices that image the flat paper laminate surfaces on both sides of the laminate, and a flat paper stack imaged by the imaging device The pixels to be inspected in order from the edge of the image on the surface are set, and the average luminance calculation areas for calculating the average luminance of the flat paper laminated surface around the pixels to be inspected are set above and below the pixels to be inspected. And an area setting means for setting a dark part detection area for detecting a dark part generated by folding of the flat paper on both the left and right sides of the pixel to be inspected. Inspection device.   The luminance difference between the luminance of the pixel to be inspected and the average luminance of the average luminance calculation area is compared with a first reference value, and the luminance difference between the average luminance of the average luminance calculation area and the minimum luminance of the dark part detection area The flat paper folding inspection apparatus according to claim 7, further comprising a comparison unit that compares the value with a second reference value.