JP4271683B2 - Inspection monitoring device for printing press - Google Patents

Description

  The present invention relates to an inspection monitoring apparatus for a printing press that detects printing defect determination and ink density variation using an image of a printed matter imaged by one imaging means.

  2. Description of the Related Art Conventionally, there are an inspection device that performs a defect determination method such as a stain, a print color tone inspection device (color tone monitoring device) that checks a change in ink density, and the like as methods for checking print quality online (for example, Patent Documents 1 and 2) reference.).

The apparatuses described in Patent Documents 1 and 2 are, for example, those in which an image sensor that captures an image of a running continuous paper (web) is attached to an offset rotary press to perform defect inspection and color tone monitoring on the same printed matter. It is.
JP 2003-103761 A JP-A-10-329307

  Conventional inspection apparatuses attached to an offset printing machine each operate independently, and each includes an image sensor (imaging means) for imaging a printing paper surface. Therefore, in order to perform a plurality of inspections on the printing paper surface, it is necessary to attach the image sensors of the inspection apparatuses to the printing press.

  However, since a space for mounting a plurality of sensors is not usually provided in a printing press, a plurality of guide rollers are provided to mount each image sensor, and a paper path for observation / inspection (the path of the printing paper) ) Had to be made separately. For this reason, there is a problem in that remodeling of the printing machine is costly and maintenance is deteriorated. Further, since each inspection apparatus operates independently as described above, it has to be individually operated and controlled, and the operation is complicated.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a printing press inspection monitoring apparatus that can detect printing defects and color tone changes in the same manner as an independent inspection apparatus by providing one image pickup means.

  The present invention has the following configuration as means for solving the above problems.

(1) an imaging unit that captures an image of a printed matter discharged from the printing machine;
Reference image storage means for storing reference image data of the printed matter;
First accumulating means for accumulating images captured by the image capturing means a predetermined number of times for each print cycle of the printed matter;
A first data processing unit for detecting a printing defect by comparing the image data accumulated by the first accumulation unit with the reference image data stored by the reference image storage unit;
Resolution conversion means for reducing and outputting the resolution of the image captured by the imaging means;
Reference image storage means for storing an image captured by dividing into a plurality of wavelength regions in units of pixels in an image whose resolution is reduced by the resolution conversion means;
Second integration means for integrating the image data output by the resolution conversion means more than the predetermined number of times for each printing cycle of the printed matter;
Using the reference image of each wavelength region stored in the reference image storage means, the amount of change in ink density is detected for each color in the pixel unit of the image with reduced resolution for the image data integrated by the second integration means. Second data processing means for
Informing means for informing contents according to a printing defect and an ink density change detected by the first data processing means and the second data processing means;
It is provided with.

In this configuration, the print image is detected by comparing the image captured by the image capturing unit and integrated a predetermined number of times with the reference image data, and the resolution is decreased by capturing the image by the image capturing unit, which is greater than the predetermined number of times. The amount of change in the ink density is detected by comparing the image obtained by integrating the number of times with each reference density of the ink of a plurality of colors in units of pixels. The notification means notifies the contents corresponding to the detected printing defect and the change amount of the ink density. Therefore, the inspection inspection apparatus for a printing press processes the image data captured by the imaging unit into image data that is optimal for detecting a printing defect and image data that is optimal for detecting a change in ink density. Since the printing defect and the change in the ink density are detected, each can be detected with high accuracy. In addition, when printing defects are inspected, it is only necessary to capture what is different from the reference image when a person visually recognizes the image, and there are many small fine scratches and smudges that occur suddenly, such as ink or water splashes . For this reason, it is preferable that the image used for defect inspection has a high resolution, and sudden defects can be detected more remarkably by reducing the number of times of image integration (a certain number) . On the other hand, in order to detect a change in ink density (color tone), it is necessary to examine the density change for each ink used for printing. In addition, the area whose color tone should be monitored is an area having a predetermined area, and the normal ink density does not change abruptly. Further, by integrating the image over time for each printing cycle, it is possible to eliminate the influence that the ink density is changed due to the suddenly generated defect.

(2) The imaging means captures a multiband image divided into wavelength regions that can distinguish the absorption wavelengths of the inks of a plurality of colors used in the printed matter,
The first data processing means detects a printing defect using image data having a smaller number of bands than the second data processing means.

  In order to detect a change in color tone (ink density), it is necessary to examine a change in ink density, and it is necessary to decompose the image into each ink used for printing. For example, in the case of an image printed using four inks of Y, M, C, and K, the wavelengths of R, G, B, and Ir that can distinguish the absorption wavelengths of Y, M, C, and K inks It is necessary to decompose the image into four wavelength regions. On the other hand, since it is sufficient for the defect inspection of printing to capture a different image from the reference image when a person visually recognizes the image, it is not necessary to decompose the image for each of all inks used for printing. In the case of an image printed using four inks of C and K, a defect generated in the printed image can be detected without any problem by decomposing it into an image in the RGB wavelength region which is the three primary colors of light. Therefore, in the first data processing means, by reducing the cumulative number of images (first number) as described above, sudden defects can be detected more prominently, so the load of printing defect detection processing increases. However, since the number of images used for the defect detection process can be reduced, the load on the first data processing means can be reduced.

  (3) The printing press is an offset rotary press, and the printed matter is a web-like continuous paper.

  In this configuration, by using the color tone monitoring device for the offset rotary press, it is possible to detect the change amount of the ink density in the image for each printing cycle printed on the continuous paper on a pixel basis.

  According to the present invention, image data picked up by the image pickup means is processed by two different processes, and image data that is optimal for detecting a printing defect and image data that is optimal for detecting a change in ink density are obtained. Therefore, printing defects and changes in ink density can be detected with high accuracy.

  In addition, since an image having a high resolution is used as an image used for defect inspection, and the number of times of image integration is set to a fixed number of times capable of detecting an unexpected defect, the accuracy of detecting an unexpected defect can be improved. On the other hand, in order to detect a change in ink density, the print image is decomposed for each ink used, the resolution is lowered, the image is averaged for each predetermined area, and the image data is more than a certain number of times for each print cycle. Since the number of times is accumulated, it is possible to eliminate the influence of a sudden change in the ink density due to a suddenly generated defect.

  In the following description, a configuration in which a printing press inspection monitoring device is attached to an offset rotary press as an example of a printing device will be described as an example. FIG. 1 is a configuration diagram showing an outline of an offset rotary press.

  The web offset press 101 supplies web-like continuous paper P from the roll paper R set in the paper feeding device 102, and the printing unit 103 performs black (hereinafter referred to as “K”) / cyan (hereinafter referred to as “Kyan”). C)) ・ Magenta (hereinafter referred to as “M”) and yellow (hereinafter referred to as “Y”) are printed on both sides of the continuous paper P in order, and the continuous paper P is heated by the dryer 104. dry. Then, the continuous paper P is cooled by the cooling drum 105, the cut-off adjustment is performed by the adjusting roller 106, the meandering correction of the continuous paper P is performed by the web guide device 107, and the continuous paper P is made a predetermined size by the triangular plate 108. Bend it. Imaging units 21 </ b> A and 21 </ b> B are provided between the web guide device 107 and the triangular plate 108 provided on the downstream side of the cooling drum 105. The imaging units 21A and 21B image the front surface (front cylinder side) and the back surface (back cylinder side) of the running printing paper surface where printing of each ink of YMCK is completed by the printing unit 103. The printing unit 103 is provided with an ink key adjusting device 109. The ink key adjusting device 109 controls the opening degree of the ink key according to a control signal from the inspection monitoring device 1 for a printing press or according to an operation of an operator. adjust.

  FIG. 2 is a block diagram showing a schematic configuration of the inspection monitoring apparatus for a printing press according to the embodiment of the present invention. Here, FIG. 2 shows only the configuration for monitoring the color tone of the image captured by the imaging unit 21A. However, the configuration for capturing the image printed on the continuous paper P by the imaging unit 21B and monitoring the color tone is as follows. The configuration is the same as the configuration shown in FIG.

  Here, when inspecting a printing defect, it is not necessary to decompose the color image into images for each ink, and it is only necessary that a portion different from the reference color image can be detected as a printing defect when visually recognized by a person. Therefore, it is only necessary to inspect the defect for the three bands of images in the RGB wavelength regions, which are the three primary colors of light. In addition, defects that occur in a printed image are often fine or small, and often occur suddenly, such as stains that are generated when ink or water droplets adhere. Therefore, when inspecting a printing defect, the defect can be detected more reliably with a finer resolution and with a reduced number of image integrations.

  On the other hand, when monitoring (inspecting) the color tone, it is necessary to examine changes in ink density. In this case, it is necessary to detect the ink amount of each image by decomposing the color image into the image of each ink actually used, not the apparent color. That is, an image decomposed into wavelength regions of four bands of R, G, B, and Ir is necessary. The area for monitoring the color tone has a certain area, and the ink density does not change abruptly while the offset rotary press 101 prints an image on the continuous paper P. Therefore, the resolution of the image printed on the continuous paper P imaged by the imaging unit 21A is reduced, and the image data (the amount of reflected light) is averaged in units of pixels in the reduced image, that is, in units of several pixels of the original image. I do. In addition, the image data (the amount of reflected light) is advantageous because, for example, time integration is performed for each printing cycle, thereby eliminating (thinning) the influence of image defects.

  Therefore, the inspection monitoring apparatus 1 for a printing press according to the present invention is configured to perform defect inspection and color tone monitoring based on the above contents.

  As shown in FIG. 2, the inspection inspection apparatus 1 for a printing press continuously captures an image of a printing surface on a continuous paper P that is printed by an offset rotary press 101 and travels, and based on this image, the ink density is measured. Monitor changes and display ink density transitions.

  The printing machine inspection monitoring apparatus 1 includes an imaging unit 21A, an integrator 22, an integration memory 23, a resolution converter 24, an integrator 26, an integration memory 27, a timing controller 28, a data processing unit 31, a data processing unit 32, and a control. CPU 41, indicator lamp 42, display monitor 43, operation panel 44, and memory 45.

  As described later, the imaging unit 21A receives light irradiated from a light source (not shown) and reflected from the surface of the continuous paper P, and receives red (hereinafter referred to as R) and green (Green: green). Hereinafter, the image data is captured in four wavelength regions of Blue, Blue (hereinafter referred to as B), and Infrared rays (hereinafter referred to as Ir). The integration memory 23, the resolution converter 24, the integration unit 26, and the integration memory 27 each have a configuration for processing image data captured in four wavelength regions of R, G, B, and Ir. However, for simplification of description, in the following description, each of the above parts will be described together without being divided into four wavelength regions. The light source (not shown) may irradiate light including all wavelengths of visible light, or may irradiate light including only four wavelength regions of R, G, B, and Ir. However, a plurality of light sources may be used.

  The imaging unit 21A is a line type image sensor, and a line type CCD or CMOS sensor is preferable. The imaging unit 21A includes, for example, four types of filters of R, G, B, and Ir. The imaging unit 21A receives light reflected from the surface of the continuous paper P by being irradiated from a light source (not shown), and Y, M, and C An image printed on the continuous paper P is picked up by dividing into four wavelength regions of R, G, B, and Ir, which are wavelength regions in which the absorption wavelength of K ink can be distinguished.

  Here, in the inspection monitoring apparatus 1 for a printing press, light received from a light source (not shown) and reflected from the surface of the continuous paper P is received and divided into four wavelength regions of R, G, B, and Ir. By capturing an image printed on the continuous paper P and performing image conversion, it is possible to detect the density of each of the Y, M, C, and K inks of each pixel in the image. In other words, C ink mainly absorbs R light and reflects G and B light, so that the density of C ink, which is a color obtained by adding G and B light, is imaged through an R filter. And K ink density can be measured. Since M ink mainly absorbs G light and reflects R / B light, it picks up an image of the printed matter through the G filter, so that M ink density and K, which is a color obtained by adding R / B light, are used. Can be measured. Since Y ink mainly absorbs B light and reflects R / G light, by picking up an image of the printed matter through the B filter, Y ink density and K, which is a color obtained by adding R / G light, are used. Can be measured. Moreover, since the density of K ink can be measured by imaging a printed matter through an Ir filter, it is possible to perform image conversion processing together with image data captured through R, G, and B filters. The density of each ink of Y, M, C, and K in each pixel in the image can be detected.

  The imaging unit 21A may be a single plate type or a four-plate type, but the imaging unit 21A is a four-plate type line CCD as shown in FIG. In addition, the imaging unit 21A is not limited to a configuration including four types of filters, and may be configured to further include a plurality of types of filters. For example, when a special color ink is used for printing, a filter capable of detecting a change amount of the ink density of the special color ink may be added.

  The imaging unit 21A detects the moving distance of the continuous paper P using an encoder (not shown) or the like, and continues every time the continuous paper P moves a certain distance so that the image of the continuous paper P becomes a continuous image without interruption. The image printed on the paper P is captured. In addition, since the pattern printed on the continuous paper P in the offset rotary press 101 is repeated at regular intervals, the imaging unit 21A determines that one cycle of the pattern is based on a signal output from an encoder (not shown). An image printed on the continuous paper P is picked up so as to form one image. The imaging unit 21A outputs the captured R, G, and B image data to the integrator 22 with the same resolution. The imaging unit 21A outputs the captured R, G, B, and Ir image data to the resolution converter 24 with the same resolution.

  The accumulator 22 adds (accumulates) the pixel unit data output by the imaging unit 21A to the pixel unit data of the image already stored in the accumulation memory 23, and stores the contents stored in the accumulation memory 23 as a new image. Update to data.

  When integrating the image data a predetermined number of times (for example, once or twice), the integration memory 23 outputs the integrated image data to the data processing unit 31.

  The resolution converter 24 reduces the resolution of each image data to a preset resolution and outputs it to the accumulator 26. For example, the resolution converter 24 averages the image data in units of several pixels for each image data output from the imaging unit 21A, and then outputs the averaged image data to the accumulator 26.

  The accumulator 26 adds (accumulates) the pixel unit data output from the resolution converter 24 to the pixel unit data of the image already stored in the accumulation memory 27, and newly stores the contents stored in the accumulation memory 27. Update to image data.

  The integration memory 27 outputs the integrated image data to the data processing unit 32 when integrating the image data more than a predetermined number of integrations (for example, 100 times) that the integration memory 23 integrates.

  The timing controller 28 sets the number of times that the integrator 22 integrates image data and the number of times that the integrator 26 integrates image data. For example, the timing controller 28 controls to output data to the data processing unit 31 every time the integrator 22 integrates image data once or twice, and the integrator 26 adds 100 to the image data. It is set so that data is output to the data processing unit 32 every time it is performed.

  The integration memory 23 and the integration memory 27 are cleared at the start of each integration.

  The data processing unit 31 receives data suitable for image defect inspection processing output from the integration memory 23 and performs image defect inspection processing. That is, in the reference processing for setting the reference data, the data processing unit 31 stores the image data as reference data for print defect inspection when the integration is completed and the image data is output from the integration memory 23. In addition, the data processing unit 31 stores each image data output from the integration memory 23 and each reference data for print defect inspection stored during the reference processing at the time of defect inspection of the image printed on the continuous paper P. Comparing comprehensively, image defects are detected. The data processing unit 31 outputs the image defect inspection result to the control CPU 41.

  The data processing unit 32 receives data suitable for image color tone monitoring (ink density change detection) output from the integration memory 27, and performs image color tone monitoring processing. That is, during the reference processing for setting the reference data, the data processing unit 32 stores the image integration data as reference data for color tone monitoring when the integration is completed and the image data is output from the integration memory 27. In addition, the data processing unit 32 comprehensively combines each image data output from the integration memory 27 and each reference data for color monitoring stored during the reference processing when monitoring the color tone of the image printed on the continuous paper P. In comparison, a change in color tone, that is, a change in ink density is detected. Then, the data processing unit 32 outputs the color tone monitoring result to the control CPU 41.

  The control CPU 41 integrates and processes the defect inspection result output from the data processing unit 31 and the color tone monitoring result output from the data processing unit 32. That is, the control CPU 41 performs a process of causing the display monitor 43 to display a graph of the change amount of the ink density and information regarding printing defects. Further, the control CPU 41 performs a process of notifying the operator of the magnitude of the change in the ink density and the occurrence of a printing defect by the number of lighting lamps and the lighting color of the indicator lamp 42.

  Further, the control CPU 41 is connected to the offset rotary press 101 through a control line as necessary, and outputs a control signal to another alarm device or inputs a status signal of the offset rotary press 101 for monitoring. It is possible to perform processing so as to change the processing of the result. Further, the control CPU 41 records the monitoring result in the memory 45, and the user can refer to the monitoring result at any time by operating the operation panel 44.

In addition, in the integration memory 23, the change can be averaged by performing the integration a plurality of times. However, for example, by setting the number of integrations to 1 time, it is possible to reliably detect defects at each printing cycle. Doo ing.

  As described above, in the inspection inspection apparatus 1 for a printing press, the image data captured by the imaging unit 21A and accumulated by the integrator 22 in the integration memory 23 a certain number of times (for example, once or twice) and the data processing unit 31 A print defect is detected by comparing the stored reference image data for defect inspection. Further, an image captured by the image capturing unit 21A, reduced in resolution by the resolution converter 24, and accumulated by the accumulator 26 in the accumulating memory 27 more than a certain number of times (for example, 100 times) and a data processing unit 32 are stored. The ink density change is detected by comparing with the reference image data for detecting the ink density. Then, the control CPU 41 informs the contents according to the detected printing defect and change in ink density by the indicator lamp 42 and the display monitor 43. Therefore, the inspection inspection apparatus for a printing press processes the image data captured by the imaging unit into image data that is optimal for detecting a printing defect and image data that is optimal for detecting a change in ink density. Since the printing defect and the change in the ink density are detected, each can be detected with high accuracy.

  Further, in the printing press inspection and monitoring apparatus 1, the operator can easily know the occurrence of printing defects and the change in ink density in the offset rotary press 101 by confirming the contents of notification by the indicator lamp 42 and the display monitor 43. On the basis of this information, the state of the offset rotary press 101 can be confirmed and the ink density can be adjusted.

  In the above description, the case where the present invention is applied to an offset rotary press is described as an example. However, the field of application of the present invention is not limited to this, and can naturally be applied to a sheet-fed printing press. In addition, the present invention can be applied to a field in which an object moving continuously at a constant speed is continuously imaged and a field in which a conventional line sensor is used. For example, the present invention can be applied to an apparatus that captures an image of an object with a quality inspection apparatus for printed matter, a quality inspection apparatus for paper and film, and the like.

  Applicable to the field of continuous imaging of objects moving continuously at a constant speed, the field where conventional line sensors are used, for example, the field of quality inspection equipment for printed matter, paper, film, etc. it can.

It is a block diagram which shows the outline of an offset rotary press. It is the block diagram which showed schematic structure of the inspection monitoring apparatus for printing presses concerning embodiment of this invention.

Explanation of symbols

  1-Inspection monitoring device for printing press 21A, 21B-Imaging unit 22, 26-Accumulator 23, 27-Accumulation memory 24-Resolution converter 28-Timing controller 31, 32-Data processing unit 41-CPU for control 42- Indicator light 43-Display monitor 44-Operation panel 45-Memory 101-Offset rotary press 102-Feeding device 103-Printing unit 104-Dryer 105-Cooling cylinder 106-Adjust roller 107-Web guide device 108-Triangle plate 109-Ink key Adjusting device P-continuous paper

Claims (3)

An image pickup means for picking up an image of the printed matter discharged from the printing press;
Reference image storage means for storing reference image data of the printed matter;
First accumulating means for accumulating images captured by the image capturing means a predetermined number of times for each print cycle of the printed matter;
A first data processing unit for detecting a printing defect by comparing the image data accumulated by the first accumulation unit with the reference image data stored by the reference image storage unit;
Resolution conversion means for reducing and outputting the resolution of the image captured by the imaging means;
Reference image storage means for storing an image captured by dividing into a plurality of wavelength regions, in units of pixels in an image whose resolution is reduced by the resolution conversion means;
Second integration means for integrating the image data output by the resolution conversion means more than the predetermined number for each print cycle of the printed matter;
Using the reference image of each wavelength region stored in the reference image storage means, the amount of change in ink density is detected for each color in the pixel unit of the image with reduced resolution for the image data integrated by the second integration means. Second data processing means for
Informing means for informing contents according to a printing defect and an ink density change detected by the first data processing means and the second data processing means;
Inspection and monitoring device for printing press equipped with. The imaging means captures a multiband image divided into wavelength regions that can distinguish the absorption wavelength of each color ink used in the printed matter,
2. The inspection and monitoring apparatus for a printing press according to claim 1, wherein the first data processing unit detects a printing defect using image data having a smaller number of bands than the second data processing unit.   The color monitoring apparatus according to claim 1, wherein the printing press is an offset rotary press, and the printed matter is a web-like continuous paper.

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