JP2024065376A - Image Inspection Equipment - Google Patents

Abstract

[Problem] To identify the device causing the deterioration of the inspection result and reduce the work required to eliminate the cause. [Solution] The system includes: conveying units 11, 12 that convey an object M on which an image has been formed in a printing unit; imaging units 131, 141 that capture images OB11, OB13 of the object M conveyed by the conveying units 11, 12; an image inspection unit 15 that compares and inspects the photographed data of the images OB11, OB13 captured by the imaging units 131, 141 with image data PD11 used when forming the images OB11, OB13 in the printing unit; and a control unit 15 that identifies whether the cause of the defect is the printing unit or the conveying units 11, 12 based on the number of defective pixels E11-E15, E21 determined to be defective by the image inspection unit 15, and determines whether the cause of the defect is the conveying units 11, 12 if the number of defective pixels is equal to or greater than an inspection threshold, and determines whether the cause of the defect is the printing unit if the number of defective pixels is less than the inspection threshold, and controls a recovery operation to eliminate the defect according to the identified cause. [Selected Figure] Figure 1

Description

The present invention relates to an image inspection device.

In an apparatus that inspects an image formed on an object to be inspected on a sheet by capturing the image formed on the object to be inspected using a camera or the like in an inspection unit, a configuration is known for positioning the object to be inspected being transported by a conveyor belt within the depth of field for capturing the image. For example, the image inspection apparatus disclosed in Patent Document 1 proposes a configuration in which suspension wires connected to the four corners of a platen placed on the back side of the conveyor belt are wound up around a pulley in a support unit that mounts the inspection unit, and the platen is pressed against the tips of the support legs at the four corners of the support unit.

In the image inspection device of Patent Document 1, when the platen is positioned and fixed so that it coincides with a virtual plane defined by the tip surface of each support leg, the distance between the object to be inspected on the conveyor belt and the inspection unit becomes a constant value. By keeping the distance between the object to be inspected and the inspection unit constant, for example, even if a CIS (Contact Image Sensor, the same applies below) with a low depth of field is used as the device for the inspection unit, the image formed on the object to be inspected can be inspected with the desired accuracy.

JP 2020-32634 A

If deterioration of parts over time or malfunction occurs in the structural parts related to the positioning of the platen, the position of the positioned platen may deviate from the virtual plane, and the object to be inspected may be placed at a position that is outside the depth of field of the camera in the inspection section. If the position of the object to be inspected deviates from the depth of field, the image of the object to be inspected taken by the camera will be out of focus and blurred, making it impossible to obtain good inspection results in image inspections using the captured image. If the inspection results deteriorate, it is necessary to identify the cause of the deterioration and take measures to eliminate the cause.

The cause of poor inspection results from image inspection equipment is not necessarily the image inspection equipment itself. When performing recovery work to eliminate the cause of the poor inspection results, it is necessary to identify the equipment that caused the problem. If the workers performing the recovery work also have to identify the equipment that caused the problem, this places a heavy burden on the workers and increases the time it takes to complete the recovery work.

The present invention has been developed in consideration of the above circumstances, and its purpose is to identify the device that is causing the deterioration of the test results and reduce the work required to eliminate the cause.

In order to achieve the above object, an image inspection apparatus according to one aspect of the present invention comprises:
a conveying unit that conveys the object on which the image is formed by the printing unit;
an imaging unit that captures an image of the inspection object transported by the transport unit;
an image inspection unit that compares and inspects the photographed data of the image photographed by the imaging unit and image data used when forming the image in the printing unit;
a control unit that identifies whether the cause of the defect is the printing unit or the conveying unit based on the number of defective pixels determined by the image inspection unit to be defective, determining that the cause of the defect is the conveying unit if the number of defective pixels is equal to or greater than an inspection threshold, and determining that the cause of the defect is the printing unit if the number of defective pixels is less than the inspection threshold, and controls a recovery operation to eliminate the defect according to the identified cause;
The present invention is characterized by comprising:

The present invention makes it possible to identify the device causing the deterioration of test results and reduce the amount of work required to resolve the cause.

FIG. 1 is a diagram showing an example of a schematic configuration of an image inspection device according to an embodiment of the present invention. FIG. 2 is a flowchart showing an example of a processing procedure executed by the microcontroller of the image inspection apparatus of FIG. FIG. 3A is a diagram for explaining a comparative inspection of a medium on which stains have occurred when an image is printed by a printing device. FIG. 3B is a diagram for explaining comparative inspection of media when misalignment of the platen occurs in the image inspection apparatus of FIG. FIG. 4 is a diagram showing the types of comparison inspection output by the image inspection apparatus of FIG. 1 and the contents of recovery operations instructed according to the inspection results. FIG. 5 is a flowchart showing an example of a procedure when the image inspection apparatus of FIG. 1 issues an alert.

Below, an embodiment of the present invention will be described with reference to the drawings. The same or equivalent parts and components are given the same or equivalent reference numerals throughout the drawings. However, it should be noted that the drawings are schematic and may differ from the actual product. In addition, the drawings may of course include parts with different dimensional relationships and ratios.

The embodiments shown below are merely examples of devices that embody the technical ideas of this invention, and the technical ideas of this invention do not limit the layout of each component to those shown below. The technical ideas of this invention can be modified in various ways within the scope of the claims.

The image inspection device 10 of the embodiment shown in FIG. 1 inspects an image printed (formed) on a medium M, which is an object to be inspected, in a printing device (printing section) not shown. The medium M can be, for example, a sheet of paper (cut paper). The printing device can print an image on one or both sides of the medium M.

The image inspection device 10 includes a first transport unit 11, a second transport unit 12, a first inspection unit 13, a second inspection unit 14, and a controller 15. The image inspection device 10 further includes a paper feed port 16 and a paper discharge port 17. The paper feed ports 16, 17 can be arranged, for example, on the left and right sides of the image inspection device 10. The medium M is transported horizontally along a transport path R inside the image inspection device 10 from the paper feed port 16 to the paper discharge port 17.

The first transport unit 11 and the second transport unit 12 constitute a transport unit that transports a medium M on which an image is printed in a printing device (not shown).

The first transport unit 11 is provided in the image inspection device 10 and is disposed below the portion of the transport path R closer to the paper feed opening 16. The second transport unit 12 is provided in the image inspection device 10 and is disposed above the portion of the transport path R closer to the paper discharge opening 17. The first transport unit 11 has a transport belt 111, a platen 112, and a lifting unit 113. The second transport unit 12 has a transport belt 121, a platen 122, and a lifting unit 123.

The conveyor belt 111 can be composed of an endless belt stretched over a pair of conveyor rollers 114, 114 and a pair of guide rollers 115, 115. The platen 112 is disposed on the rear side of the portion of the conveyor belt 111 between the pair of conveyor rollers 114, 114, parallel to the conveying path R.

The conveying belt 121 can be configured as an endless belt stretched over a pair of conveying rollers 124, 124 and a pair of guide rollers 125, 125. The platen 122 is disposed on the rear side of the portion of the conveying belt 121 between the pair of conveying rollers 124, 124, parallel to the conveying path R.

The conveying belt 111 can, for example, adsorb the medium M fed from the paper feed port 16 to the portion between the conveying rollers 114 and convey the medium to the middle of the conveying path R. The conveying belt 121 can, for example, adsorb the medium M that has been conveyed to the middle of the conveying path R and separated from the conveying belt 111 to the portion between the conveying rollers 124 and convey the medium M from the middle of the conveying path R to the paper discharge port 17.

The lifting unit 113 can raise and lower the platen 112 to move the portion of the conveyor belt 111 between the conveyor rollers 114, 114 up and down. The lifting unit 123 can raise and lower the platen 122 to move the portion of the conveyor belt 121 between the conveyor rollers 124, 124 up and down. The configuration of the lifting units 113, 123 will be described later.

The first inspection unit 13 is disposed above the portion of the conveying path R near the paper feed port 16. The first inspection unit 13 faces the portion of the conveying belt 111 between the conveying rollers 114, 114. The first inspection unit 13 has a line camera 131 and an area camera 132.

The second inspection unit 14 is disposed below the portion of the conveying path R near the paper discharge port 17. The second inspection unit 14 faces the portion of the conveying belt 121 between the conveying rollers 124, 124. The second inspection unit 14 has a line camera 141 and an area camera 142.

The line cameras 131 and 141 can be configured, for example, by a CIS. A CIS is an image sensor having a linear sensor array. The line cameras 131 and 141 are arranged with the longitudinal direction of the sensor array facing the width direction of the medium M. The width direction of the medium M is perpendicular to the transport direction X of the medium M adsorbed to the transport belts 111 and 121. The line cameras 131 and 141 have a length equal to or greater than the full width in the width direction of the image of the medium M.

The line camera 131 can scan the image printed on the top surface of the medium M over the entire length in the transport direction X while the medium M is being transported by the transport belt 111, and read the entire image on the top surface. The line camera 141 can scan the image printed on the bottom surface of the medium M over the entire length in the transport direction X while the medium M is being transported by the transport belt 121, and read the entire image on the bottom surface. The image data read by the line cameras 131, 141 can be used for image inspection.

The area cameras 132 and 142 can be configured, for example, with an image sensor having a matrix array. The area camera 132 can read characters, codes, etc. printed, for example, on a predetermined portion of the top surface of the medium M being transported by the transport belt 111. The area camera 142 can read characters, codes, etc. formed, for example, on a predetermined portion of the bottom surface of the medium M being transported by the transport belt 121. The image data of characters, codes, etc. read by the area cameras 132 and 142 can be used, for example, to inspect whether the image of the top surface and the image of the bottom surface of the medium M are consistent.

In this embodiment, the line cameras 131 and 141 constitute an imaging section that captures an image of the inspection object being transported by the transport section. The image data read by the line cameras 131 and 141 corresponds to the photographic data of the image captured by the imaging section.

The lifting units 113, 123 are configured, for example, using the structure of Patent Document 1, which is cited as a prior art document, in which the suspension wires at the four corners of the platen are wound up and positioned. In the lifting units 113, 123 using the structure of Patent Document 1, for example, the suspension wires at the four corners of the platens 112, 122 are wound up around pulleys on the support part of the first inspection unit 13 and the support part of the second inspection unit 14 (neither shown). When the platens 112, 122 are pressed against the support legs at the four corners of the support parts by winding up the suspension wires, the platens 112, 122 can be positioned on an imaginary plane defined by the tip surfaces of the support legs.

When the platens 112, 122 are positioned on a virtual plane, the medium M being transported by the transport belts 111, 121 is positioned within the depth of field of the line cameras 131, 141 and the area cameras 132, 142.

The controller 15 has, for example, a general-purpose microcontroller. The microcontroller has a CPU (Central Processing Unit) and a memory. The memory includes a ROM (Read Only Memory) and a RAM (Random Access Memory). The microcontroller can virtually construct multiple information processing circuits by having the CPU execute a program stored in the memory.

In this embodiment, an example is shown in which multiple information processing circuits built in a microcontroller are realized by software. Of course, it is also possible to prepare dedicated hardware for executing each of the information processes shown below and configure the information processing circuits. Also, multiple information processing circuits may be configured by individual hardware. Dedicated hardware includes devices such as application specific integrated circuits (ASICs) arranged to execute the functions of each information processing circuit, and conventional circuit components.

The microcontroller of the controller 15 can configure an image inspection unit and a control unit using multiple virtually constructed information processing circuits.

The image inspection unit compares and inspects the image data read from the top and bottom surfaces of the medium M by the line cameras 131, 141 constituting the imaging unit, respectively, with the print data used when printing the image on the top and bottom surfaces of the medium M in the printing device. The image inspection unit can obtain the print data for the top and bottom surfaces of the medium M from the printing device. The print data corresponds to the image data used when forming the image in the printing unit.

The image inspection unit compares the pixel values of the image data read by the line cameras 131, 141 with the pixel values of the print data for each of the top and bottom surfaces of the medium M, with pixels corresponding to the same position in the image. The image inspection unit detects pixels where the comparison result between the pixel value of the image data and the pixel value of the print data is poor, for example, for the same pixel on the same surface. A poor comparison result can mean, for example, that the pixel value of the image data and the pixel value of the print data differ by more than a predetermined threshold value.

For example, if dirt occurs on the medium M when printing an image using a printing device (not shown), the dirt will cause an increase in the number of defective pixels that result in a poor comparison.

Contamination of the medium M during printing occurs, for example, in an inkjet printing device, when satellites of ink droplets land at positions on the medium M that are shifted from the landing positions of the ink droplets, or when the medium M comes into contact with the inkjet head. Contamination of the medium M during printing can also occur when residual ink adhering to the ejection surface of the inkjet head falls onto and adheres to the medium M. Contamination of the medium M during printing can be eliminated, for example, by a cleaning operation in the printing device. The cleaning operation can include, for example, the inkjet head. The target of the cleaning operation may also include other than the inkjet head.

When a part of an image printed on medium M by a printing device is missing, that missing part also causes an increase in the number of defective pixels, which are defective pixels in the comparison results. Missing parts in an image occur, for example, when paper dust or the like that was attached to medium M when the image was printed falls off medium M after printing.

In the image inspection device 10 of this embodiment, if deterioration of parts over time or malfunction occurs in the structural parts that make up the lifting units 113, 123, the positions of the platens 112, 122, which have been positioned by winding the suspension wires, may deviate from the position on the virtual plane. If the positions of the positioned platens 112, 122 deviate from the virtual plane, there is a possibility that the medium M being transported by the transport belts 111, 121 will no longer be positioned within the depth of field of the line cameras 131, 141 and the area cameras 132, 142.

In particular, the lifting section 113 of the first inspection section 13, which is located above the transport path R, employs a mechanism that brings the platen 112 suspended by a suspension wire into contact with a support section (not shown) against gravity, which can easily lead to misalignment due to deterioration over time or malfunction.

If the medium M being transported is not positioned within the depth of field of the line cameras 131, 141, the image of the medium M read by the line cameras 131, 141 will be blurred due to focus deviation. If the image of the medium M read by the line cameras 131, 141 is blurred, it will be difficult for the pixel values of the image data read by the line cameras 131, 141 and the pixel values of the print data to match for pixels corresponding to the same position in the image. Blurring of the image of the medium M read by the line cameras 131, 141 will cause an increase in the number of defective pixels, which result in a poor comparison.

When the number of defective pixels increases, the cause of the defective pixel value comparison result may be on the printing device side, as described above, or on the image inspection device 10 side. Recovery work to eliminate the cause of the defective pixel comparison result needs to be carried out by identifying the device where the cause occurred.

The control unit determines whether the cause of the comparison result being defective is the printing device (not shown) or the conveying unit (first conveying unit 11 and second conveying unit 12) of the image inspection device 10, based on the number of defective pixels determined to be defective as a result of the comparison. If the number of defective pixels is equal to or greater than the inspection threshold, the control unit determines that the cause of the defect is the conveying unit, and if the number of defective pixels is less than the inspection threshold, the control unit determines that the cause of the defect is the printing device. The control unit controls a recovery operation to eliminate the defect according to the identified cause. The details of the control of the recovery operation will be described later.

Next, an example of the procedure for processing image inspection and recovery operation control performed in cooperation between a printing device (not shown) and the image inspection device 10 will be described with reference to the flowchart in FIG. 2.

First, the printing device (not shown) checks the maintenance mode setting (step S101). If the maintenance mode setting is invalid, the printing device ends the series of processes related to image inspection and recovery operation control. If the maintenance mode setting is valid, the printing device registers print data of a comparison image to be used for image inspection by comparison inspection (step S103).

Next, the controller 15 checks whether the number of consecutive NG (defective) results in the image inspection using the comparison image is less than a threshold value or equal to or greater than the threshold value (step S105). If the number of consecutive NG (defective) results in the image inspection is equal to or greater than the threshold value (exceeding), the reproducibility of defects is high, so it can be assumed that the cause of the NG (defective) inspection result is not due to an uncertain factor but due to a hardware defect.

Hardware defects are, for example, defects that cause stains on the medium M, missing images, or blurred images of the medium M read by the line cameras 131 and 141 of the image inspection device 10, as described above, that occur when the printing device prints.

If the number of consecutive NG (defective) results in the image inspection is less than the threshold, the series of processes related to the image inspection and recovery operation control is terminated. If it is equal to or greater than the threshold (exceeds), the print data of the comparison image is used to print an image of the imaging data on the medium M (step S107). The image may be printed by single-sided printing (only the top surface of the medium M) or double-sided printing (top and bottom surfaces of the medium M).

Then, the controller 15 of the image inspection device 10 performs a comparison inspection on the medium M on which the image of the imaging data is printed in the image inspection section, comparing (inspecting) the comparison data and the imaging data by a comparison inspection (step S109). The comparison inspection can be performed by comparing the image data read from the medium M by the line cameras 131, 141 with the print data used when printing (forming) the image on the medium M in the printing device (printing section) at pixels corresponding to the same positions in the image. In the comparison inspection, the number of pixels (number of defective pixels) where the pixel values of the image data and the pixel values of the print data do not match are counted.

If medium M is printed on one side, the comparison inspection is performed on the top surface of medium M. If medium M is printed on both sides, the comparison inspection is performed on both the top and bottom surfaces of medium M.

Figure 3A is a diagram explaining a comparative inspection of a medium M on which stains occurred when an image was printed in a printing device. The medium M shown on the far left of Figure 3A has satellite dots D11-D15 attached thereto when image OB11 of "A" (an image formed on the object to be inspected in the printing section) was printed. When image OB11 is printed on the top surface of medium M, line camera 131 of image inspection device 10 reads dots D11-D15 from the top surface of medium M together with image OB11.

On the other hand, the print data PD11 used by the printing device to print image OB11, shown in the center of Figure 3A, contains only image data PI11 for pixels corresponding to image OB11, and does not contain image data for pixels corresponding to dots D11 to D15.

The comparative inspection of the image data read by the line camera 131 of the image inspection device 10 from the top surface of the medium M with the print data PD11 is performed by comparing the image data read by the line camera 131 with the print data PD11. As shown in the inspection data CD11 shown on the far right of Figure 3A, in which the image data read by the line camera 131 is superimposed with the print data PD11, defective areas E11 to E15, where the pixel values do not match, occur in the pixel areas corresponding to dots D11 to D15. Defective areas E11 to E15 correspond to defective pixels that the image inspection unit has determined to be defective.

Figure 3B is a diagram illustrating comparative inspection of medium M when the position of the platen 112 is shifted in the image inspection device 10. The top surface of medium M photographed by the line camera 131 of the image inspection device 10 is out of the depth of field of the line camera 131 due to the position shift of the platen 112. As shown on the far left of Figure 3B, when an image OB13 of "A" (an image formed on the object to be inspected in the printing section) is printed on the top surface of medium M, the image OB11 read by the line camera 131 from the top surface of medium M becomes blurred due to focus shift. As shown in the center of Figure 3B, in the data SD11 of the image of the top surface of medium M photographed by the line camera 131, the blurred image SI11 of "A" has a larger contour than the original image OB11.

When comparing the image data read from the top surface of the medium M by the line camera 131 of the image inspection device 10 with the print data PD11, defective areas E21, where pixel values do not match, occur along the contour of the image OB13, as shown in the inspection data CD21 shown at the far right of Figure 3B. Defective areas E21 correspond to defective pixels that the image inspection unit has determined to be defective.

From the above, if the result of the comparison test is NG (failure) due to dirt on medium M, the number of defective points E11 to E15 will be a relatively small number of pixels corresponding to the number of dots D11 to D15. Even if the result of the comparison test is NG (failure) due to a defect in image OB11 of medium M, the number of defective points will be only a number corresponding to the number of pixels with the defect, so the number of defective points will be a relatively small number of pixels.

For example, whether a defective pixel is inside or outside of image OB11 can be used as a guide to distinguish whether the cause is dirt on medium M or a defect in image OB11. In other words, the comparison inspection can be performed separately as a comparison inspection of dirt on medium M and a comparison inspection of a defect in image OB11.

On the other hand, if the result of the comparison inspection is NG (defective) because the medium M is placed outside the depth of field of the line cameras 131 and 141, the defective area E21 will have a relatively large number of pixels according to the length of the contour of the image OB11.

The number of pixels in the defective area where the comparison test result is NG (failure) can be used as a guide to determine whether the cause of the comparison test result being NG (failure) is the printing device or the image inspection device 10.

For example, if the number of defective pixels is 5 or less, it may be determined that the cause of the NG (failure) result of the comparison inspection is the printing device. Also, if the number of defective pixels reaches 50, it may be determined that the cause of the NG (failure) result of the comparison inspection is the image inspection device 10.

The controller 15 of the image inspection device 10 checks whether the number of inspection NG detections (number of defective pixels) in the image inspection section is at the maximum value (step S111). The maximum number of inspection NG detections is a number determined by the system (= inspection threshold), and is the upper limit for counting the number of mismatched pixels in an inspection to determine whether pixel values of the image bitmap match at the same pixel. The maximum number of inspection NG detections can be, for example, 50 as described above. The maximum number of inspection NG detections corresponds to the inspection threshold.

If the number of inspection failures (number of defective pixels) is not the maximum value (NO in step S111), the image inspection device 10 is not considered to be the cause, and the controller 15 of the image inspection device 10 instructs the printing device to perform a cleaning operation as a recovery operation (step S113).

When the comparative inspection of stains on medium M and the comparative inspection of defects in image OB11 are performed separately, controller 15 may distinguish between the contents of the instructions for the cleaning operation. For example, when a cleaning operation is instructed based on the results of the comparative inspection of stains on medium M, as shown in FIG. 4, a cleaning operation that suppresses stains caused by ink dripping onto medium M and contact of medium M with the inkjet head can be instructed. When a cleaning operation is instructed based on the results of the comparative inspection of defects in image OB11, a cleaning operation that suppresses printing defects caused by the adhesion of paper powder to medium M can be instructed.

When a printing device receives a cleaning operation instruction from the image inspection device 10, the printing device can perform cleaning corresponding to stains on the medium M or printing defects in the image printed on the medium M as a recovery operation (recovery action). The recovery operation can be performed automatically under control based on instructions from the image inspection device 10, for example, in a printing device in which the maintenance mode setting is enabled.

After issuing the instruction to perform the cleaning operation, the controller 15 returns to step S109 and performs the comparison inspection again. If the inspection result remains NG (defective) even after the comparison inspection is performed again, the controller 15 of the image inspection device 10 assumes that the defect in the printing device has not been resolved and issues an alert that an error has occurred in the printing device (step S115). After issuing the alert, the series of processes related to the image inspection and recovery operation control are terminated.

If the number of inspection failures (number of defective pixels) is the maximum value in step S111 (YES), the controller 15 assumes that the cause is the image inspection device 10 and checks whether the inspection result is NG (defective) on the first platen side (step S117).

The first platen side means the side of the first inspection unit 13 corresponding to the platen 112 (first platen) of the first transport unit 11. If it is the first platen side, the inspection result for the top surface of the medium M will be NG (defective). Not the first platen side means the second platen side. The second platen side means the side of the second inspection unit 14 corresponding to the platen 122 (second platen) of the second transport unit 12. If it is the second platen side, the inspection result for the bottom surface of the medium M will be NG (defective).

If the inspection result is NG (defective) on the first platen side (YES in step S117), the controller 15 instructs the belt platen on the first platen side to be operated again as a recovery operation (step S119). The belt platen on the first platen side is the platen 112 of the first conveying unit 11. Re-operating the belt platen on the first platen side is an operation to reposition the platen 112. By re-operating the belt platen, the platen 112 returns to the virtual position, and the medium M being conveyed by the conveying belt 111 is positioned again within the depth of field of the line camera 131, thereby eliminating the defocus of the image of the medium M in the line camera 131.

After issuing an instruction to restart the belt platen on the first platen side, the controller 15 returns to step S109 and performs the comparison inspection again. If the inspection result of the repeated comparison inspection remains NG (defective), the controller 15 of the image inspection device 10 infers that the defect on the first platen side has not been resolved. The controller 15 then issues an alert that an error has occurred in the platen 112 of the first conveying unit 11 (step S121). After issuing the alert, the series of processes related to the image inspection and recovery operation control are terminated.

If the inspection result is not NG (defective) on the first platen side (NO in step S117), the controller 15 instructs the belt platen on the second platen side to be operated again as a recovery operation (step S123). The belt platen on the second platen side is the platen 122 of the second conveying unit 12. Re-operating the belt platen on the second platen side is an operation to reposition the platen 122. By re-operating the belt platen, the platen 122 returns to the virtual position, and the medium M being conveyed by the conveying belt 121 is positioned again within the depth of field of the line camera 141, thereby eliminating the defocus of the image of the medium M in the line camera 141.

After issuing an instruction to restart the belt platen on the second platen side, the controller 15 returns to step S109 and performs the comparison inspection again. If the inspection result of the second comparison inspection remains NG (defective), the controller 15 of the image inspection device 10 infers that the defect on the second platen side has not been resolved. The controller 15 then issues an alert that an error has occurred in the platen 122 of the second conveying unit 12 (step S125). After issuing the alert, the series of processes related to the image inspection and recovery operation control are terminated.

Figure 5 is a flowchart showing an example of the procedure when the controller 15 of the image inspection device 10 issues an alert. Figure 5 summarizes the procedure performed in steps S109 to S125 in Figure 2.

As described above, if the result of the comparison inspection performed by the image inspection unit in the image inspection device 10 is NG (defective), the controller 15 performs a recovery action to control a recovery operation to eliminate the defect. The instructions given by the controller 15 in steps S113, S119, and S123 in FIG. 2 correspond to the first recovery action.

As shown in FIG. 5, if the result of the comparison inspection (step S201) performed by the image inspection unit is NG (defective) (YES in step S203), the controller 15 performs a first recovery action to control a recovery operation to eliminate the defect (step S205). If the result of the comparison inspection is not NG (defective) (NO in step S203), step S205 is skipped.

Next, if the result of the comparison test (step S207) performed again by the image inspection unit is NG (defective) (YES in step S209), the controller 15 performs a second recovery action (step S211). The issuance of an alert by the controller 15 in steps S115, S121, and S125 in FIG. 4 corresponds to the second recovery action. If the result of the comparison test performed again is not NG (defective) (NO in step S209), the series of processes ends.

The image inspection device 10 of this embodiment described above can identify the device that caused the comparison inspection result to be NG (defective), thereby reducing the amount of work required to resolve the cause.

When the printing device performs single-sided printing on the medium M, the second inspection unit 14 of the image inspection device 10 is not necessary, and the second transport unit 12 can be omitted instead of the first transport unit 11 spanning the entire length of the transport path R.

The present invention is not limited to the above-described embodiment, and in the implementation stage, the components can be modified and embodied without departing from the gist of the invention. In addition, various inventions can be created by appropriately combining multiple components disclosed in the above-described embodiment. For example, some components may be deleted from all the components shown in the embodiment.

[Additional Notes]
The above-described embodiment discloses the invention in the following aspects.

That is, as one embodiment of the invention,
a conveying unit that conveys the object on which the image is formed by the printing unit;
an imaging unit that captures an image of the inspection object transported by the transport unit;
an image inspection unit that compares and inspects the photographed data of the image photographed by the imaging unit and image data used when forming the image in the printing unit;
a control unit that identifies whether the cause of the defect is the printing unit or the conveying unit based on the number of defective pixels determined to be defective by the image inspection unit, determining that the cause of the defect is the conveying unit when the number of defective pixels is equal to or greater than an inspection threshold, and determining that the cause of the defect is the printing unit when the number of defective pixels is less than the inspection threshold, and controls a recovery operation to eliminate the defect according to the identified cause;
An image inspection apparatus comprising:

And according to the above aspect of the invention, it is possible to identify the device that caused the deterioration of the test results and reduce the work required to eliminate the cause.

10 Image inspection device 11 First conveying unit (conveying unit)
12 Second conveying section (conveying section)
15 Controller (image inspection unit, control unit)
131, 141 Line camera (imaging unit)
E11 to E15, E21 Defective areas (defective pixels)
M medium (test object)
OB11, OB13 images (images formed on the test object in the printing section)
PD11 Print data (image data used when forming an image in the printing unit)

Claims (1)

a conveying unit that conveys the object on which the image is formed by the printing unit;
an imaging unit that captures an image of the inspection object transported by the transport unit;
an image inspection unit that compares and inspects the photographed data of the image photographed by the imaging unit and image data used when forming the image in the printing unit;
a control unit that identifies whether the cause of the defect is the printing unit or the conveying unit based on the number of defective pixels determined to be defective by the image inspection unit, determining that the cause of the defect is the conveying unit when the number of defective pixels is equal to or greater than an inspection threshold, and determining that the cause of the defect is the printing unit when the number of defective pixels is less than the inspection threshold, and controls a recovery operation to eliminate the defect according to the identified cause;
An image inspection device comprising:

Images