JP6142606B2 - Sheet-fed printed matter inspection device - Google Patents

Description

  The present invention relates to an apparatus for inspecting print quality during printing by a sheet-fed printing machine such as an offset sheet-fed printing machine.

  An inspection device that inspects the print quality of the sheet printed material is installed in the final printing unit before the sheet printed material reaches the delivery unit in the sheet printing machine.

  In the inspection by this inspection apparatus, illumination light is irradiated from a light source to the printing surface of a sheet printed material that runs in contact with the circumferential surface of the impression cylinder of the final printing unit, and the reflected light is received as an image by a camera. Is performed by pattern matching in the image processing unit.

  During this inspection, the sheet-fed printing machine prints one color at a time while conveying the leading edge (front edge) of the printed sheet with nails, but the trailing edge is free, so the impression cylinder and blanket cylinder When the trailing edge of the sheet printed material passes through the nip point, which is a contact point, the sheet printed material is lifted from the peripheral surface of the impression cylinder or fluttered, causing distortion in the image taken by the camera, and an accurate inspection is performed. Disappear.

  In order to prevent this, conventionally, air is blown onto the printed sheet on the circumferential surface of the impression cylinder by an air nozzle, and the printed sheet is brought into close contact with the circumferential surface of the impression cylinder (see, for example, Patent Documents 1 and 2). ).

JP-A-8-142313 JP 2004-136585 A

  In the conventional method of blowing air to the printed sheet on the peripheral surface of the impression cylinder, air is constantly blown from the nozzle to the circumferential surface of the impression cylinder, so that the air contacts the blanket cylinder or the blanket cylinder. The ink flows to the plate cylinder and dries the ink adhering to the surface of the blanket cylinder or the plate cylinder, or dampening water adhering to the surface of the plate cylinder. Such drying of ink or fountain solution causes the occurrence of printing stains.

  Accordingly, an object of the present invention is to provide a sheet-fed printed matter inspection apparatus that can solve the above-described problems.

  In order to solve the above problems, the present invention employs the following configuration.

  In addition, although the code | symbol with a parenthesis is attached | subjected in order to make an understanding of this invention easy, this invention is not limited to this.

That is, the invention according to claim 1 includes an air spraying means (10) for pressing the printed sheet (a) against the peripheral surface of the impression cylinder (5) in the final printing unit (1) of the sheet-fed printing machine, and the air spraying An illuminating means (11) disposed on the upstream side of the means and irradiating light onto the printed sheet (a) pressed against the peripheral surface of the impression cylinder (5) by the air blowing means (10); and the air blowing means A camera (12) that captures an image of the sheet printed matter (a) illuminated by the illumination unit (11) on the upstream side, and a print quality determination unit that determines whether the print is good from the image captured by the camera (12) ( 13), the air blowing from the air spraying means (10) can be turned on / off, and the rear end of the sheet printed matter (a) is connected to the impression cylinder (5). Contact with Turn on the balloon of air as it passes through the nip point between the banquet cylinder (4) and (p), to clear the balloon of air after the imaging of the print image of the sheet printed material (a) is completed, the air Is blown out until the trailing edge of the printed sheet (a) passes through the air blowing position where the air is blown out after the printing of the printed image of the printed sheet (a) is completed. And the sheet | seat printed matter inspection apparatus which is downstream from the imaging point by the said camera (12) is employ | adopted for the blowing position of the said air .

  According to the present invention, the discharge of air from the nozzle device (10) is performed after the trailing edge of each printed sheet (a) passes through the nip point (p), and then the end of the printed image is an imaging point or an air blowing point. Since the air discharge is stopped at other times, the printing of the sheet printed matter (a) is prevented from fluttering and the like, and the print image is properly picked up to make an accurate print quality determination. Of course, it is possible to prevent excess air from flowing toward the blanket cylinder (4) and the plate cylinder (3), or to significantly reduce the amount of flow. Therefore, it is possible to prevent the ink and dampening water from drying on the surfaces of the blanket cylinder (4) and the plate cylinder (3), and to prevent the printing quality from being deteriorated.

It is the schematic of the rear part of the offset sheet-fed printing press provided with the sheet printed matter inspection apparatus which concerns on this invention. (A) is a front view of an air spraying device, and (B) is a cross-sectional view taken along line BB in FIG. (A) is explanatory drawing when the rear end of a sheet printed matter passes the nip point between an impression cylinder and a blanket cylinder, (B) is when the rear end of the printed image of a sheet printed matter passes an imaging point. It is explanatory drawing of.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.

  As shown in FIG. 1, a delivery unit 2 that discharges a printed sheet a that has been printed is installed next to the final printing unit 1 of the offset sheet-fed printing press.

  The final printing unit 1 is provided with a set of a plate cylinder 3, a blanket cylinder 4 and an impression cylinder 5 for printing with ink of a predetermined color.

  The delivery unit 2 has a receiving cylinder 6 disposed so as to contact the impression cylinder 5. An endless chain 7 extends from the receiving cylinder 6 to a stacking portion (not shown) of the sheet printed material a. When the printed sheet a passes between the blanket cylinder 4 and the impression cylinder 5, it is gripped on the receiving cylinder 6 by a gripping claw (not shown) attached to the endless chain 7 and conveyed to the stacking section.

  A powder spraying device 8 is provided in the middle of the endless chain 7 from the receiving drum 6 to the stacked portion. By spraying the powder from the powder spraying device 8 onto the printing surface of the sheet printed matter a, the ink show-through is prevented when the sheet printed matter a is stacked at the stacking portion.

  Further, covers 1a and 2a are attached to the final printing unit 1 and the delivery unit 2 in the vertical direction, respectively, and a step 9 on which an operator b of the printing press rides is placed between the covers 1a and 2a. Step 9 is arranged horizontally near the impression cylinder 5 of the final printing unit 1 and directly above the receiving cylinder 6 of the delivery unit 2. The operator b can take the step 9 to replenish ink, or open the cover 1a to inspect the impression cylinder 5 and the like.

  As shown in FIG. 1, an inspection device for inspecting the print quality of the sheet printed material a discharged from the final printing unit 1 is disposed between the final printing unit 1 and the delivery unit 2.

  This sheet-fed printed matter inspection apparatus includes a nozzle device 10 that is an air blowing means that presses the sheet-fed printed matter a against the peripheral surface of the impression cylinder 5 adjacent to the delivery unit 2 of the sheet-fed printing machine, and air pressure from the nozzle device 10. An illuminating device 11 that is an illuminating unit that irradiates light onto the sheet printed material a pressed against the peripheral surface of the cylinder 5, a camera 12 that captures an image of the sheet printed material a illuminated by the illuminating device 11, and a camera 12. A printing quality determination device 13 is provided that is a printing quality determination unit that determines printing quality from the captured image. Further, a reflecting mirror 14 is provided in the optical path where the reflected light from the printed sheet a reaches the camera 12.

  The nozzle device 10 is for bringing the printed sheet a into close contact with the peripheral surface of the impression cylinder 5 by blowing air toward the surface of the impression cylinder 5. Specifically, as shown in FIGS. 2 (A) and 2 (B), the nozzle device 10 has a large number of air discharge holes 10a at a predetermined pitch on one bus bar on the surface of a cylinder closed at both ends. Has a structure. The air discharge hole 10a can be formed by drilling a cylindrical wall. Preferably, the air discharge hole 10a is formed by fixing a thin pipe 15 in each of the drilled holes. A blower 16 is connected to the cylinder. When air is supplied from the blower 16 into the cylinder of the nozzle device 10, the air is blown out simultaneously from the air discharge holes 10a.

  As shown in FIG. 1, the nozzle device 10 is installed so that the air discharge holes 10 a are aligned with one bus bar of the impression cylinder 5. As a result, the air blown out from the air discharge holes 10 a hits the printing surface of the sheet printed material a, thereby bringing the sheet printed material a into close contact with the peripheral surface of the impression cylinder 5.

  As shown in FIG. 1, the illuminating device 11 is arranged such that the reflected light from the sheet printed material a on the impression cylinder 5 passes under the step 9 installed between the delivery unit 2 and the impression cylinder 5. Is done. Further, the printed sheet a is pressed against the peripheral surface of the impression cylinder 5 by the air blown out from the nozzle device 10 and is arranged so that the illumination light strikes the position where it is brought into close contact. Since the printed image is stationary with respect to the impression cylinder 5 where the sheet printed material a is in close contact with the peripheral surface of the impression cylinder 5, the printed image is taken by the camera 12 without distortion.

  Illumination device 11 is specifically composed of a light source such as an LED or a fluorescent lamp, and is provided so as to extend along the generatrix of impression cylinder 5. Illumination light from the illuminating device 11 is reflected by the printing surface of the sheet printed matter a on the impression cylinder 5, and this reflected light passes under the step 9 and reaches the reflecting mirror 14.

  On the back side of the boundary between the step 9 and the cover 2a of the delivery unit 2, a reflecting mirror 14 for directing the reflected light to the back side of the cover 2a of the delivery unit 2 is disposed. The reflecting mirror 14 is configured as a plate mirror that is elongated in parallel with the axial direction of the impression cylinder 5, similarly to the lighting device 11.

  As the reflecting mirror 14, a surface mirror formed by vapor-depositing metal on the surface of a glass plate is preferably used in order to increase inspection accuracy. When the glass plate is thin, a back mirror can be used.

  The reflecting mirror 14 is preferably covered with a protective member 14a. The protective member 14a is configured as a box-shaped case, and the portion where the reflected light passing under the step 9 enters and the portion reflected by the reflecting mirror 14 and exiting to the camera 12 are transparent plates made of transparent glass or the like. Each is shielded. By covering the reflecting mirror 14 with the protective member 14 a in this way, it is possible to prevent the powder sprayed by the powder spraying device 8 and floating in the vicinity of the delivery unit 2 from adhering to the reflecting mirror 14.

  As shown in FIG. 1, a slit 9a through which reflected light passes is formed at a location in step 9 that contacts the cover 2a of the delivery unit 2. However, the slit 9a is closed, and the reflecting mirror 14 and the protective mirror 14 are protected. It is also possible to arrange the member 14a under the step so that the optical path of the reflected light does not pass over the step 9 at all.

  The camera 12 is disposed above the cover 2a of the delivery unit 2 so as to receive the reflected light passing through the back side of the cover 2a of the delivery unit 2. The camera 12 is specifically a line sensor camera. A plurality of line sensor cameras may be arranged in the width direction of the sheet printed material a (direction perpendicular to the conveying direction of the sheet printed material) according to the resolution required for the inspection of the print quality.

  Note that the camera 12 can be arranged immediately below step 9.

  The optical path of the reflected light from the reflecting mirror 14 through the back side of the cover 2 a of the delivery unit 2 to the camera 12 is covered with an optical duct 17. The start end side of the optical duct 17 covers a transparent plate (not shown) of the protection member 14 a, and the end side extends while converging toward the lens side of the camera 12. As a result, a decrease in inspection accuracy due to the powder sprayed and scattered from the powder spraying device 8 crossing the optical path from the reflecting mirror 14 to the camera 12 is prevented.

  In order to prevent the scattered powder or ink mist from crossing the optical path of the reflected light and appearing in the image, the optical path under the step 9 may be covered with the optical duct 18.

  The print quality determination device 13 is for transferring a print image of the sheet printed matter a captured by the camera 12 to an inspection processing unit (not shown) and performing quality determination by pattern matching. Since this apparatus is a known apparatus, a detailed description thereof will be omitted.

  As described above, when air is constantly blown from the nozzle device 10 toward the peripheral surface of the impression cylinder, the ink layer formed on the surface of the blanket cylinder 4 or the fountain solution formed on the surface of the plate cylinder 3. There is a possibility that the film of the film dries and printing stains occur.

  Therefore, in the present invention, a control device is provided in which air blowing from the nozzle device 10 which is air blowing means is on / off controlled.

  Specifically, as shown in FIGS. 1 and 2A, an electromagnetic valve 19 and a regulator 20 are provided in an air supply pipe from the air compressor 16 to the nozzle device 10, and a rotary shaft of the impression cylinder 5 is provided on a rotary shaft. An encoder 5a is attached. Further, a sequencer 21 is provided, and a signal is input from the rotary encoder 5 a to the sequencer 21, and a signal is output from the sequencer 21 to the electromagnetic valve 19 and the regulator 20.

  As shown in FIG. 3A, when the trailing edge of the sheet printed material a passes through the nip point p between the impression cylinder 5 and the blanket cylinder 4 in contact therewith, the sequencer 21 turns on the solenoid valve 19. A signal is output. The nip point p extends in the direction of the generatrix at the contact point between the impression cylinder 5 and the blanket cylinder 4. The output timing of the ON signal is measured by counting the signal from the rotary encoder 5a. When the ON signal is output, the electromagnetic valve 19 is opened, and air blows out from the air discharge hole 10 a of the nozzle device 10 toward the sheet printed matter a on the circumferential surface of the impression cylinder 5. When the rear end of the sheet printed material a passes through the nip point p, the sheet printed material a is only added to a clamping claw (not shown) of the impression cylinder 5 only at the front end side, and the rear end side is released and easily flutters. Further, as a result of being pressed against the circumferential surface of the impression cylinder 5 by the jet of air, fluttering on the circumferential surface of the impression cylinder 5 is accurately prevented.

  As shown in FIG. 3B, when the rear end of the sheet printed material a arrives at the imaging point by the camera 12, imaging of the printed image is completed, and an off signal is output from the sequencer 21 to the electromagnetic valve 19. The imaging point is a point where the optical axis of the camera 12 intersects the circumferential surface of the impression cylinder 5 and extends on the circumferential surface of the impression cylinder 5 in the direction of the generatrix. The timing of outputting the off signal can be determined by measuring the end of the image to be printed in advance, and can be the time when the end of the image passes the imaging point by the camera 12. When the electromagnetic valve 19 is closed by the off signal, the blowing of air from the air discharge hole 10a is stopped, thereby preventing the air from flowing toward the blanket cylinder 4 and the plate cylinder 3.

  The air blowing may be continued until the rear end of the sheet printed material a passes through the air blowing position after the imaging of the printed image of the sheet printed material a is completed.

  The point where the axis of the nozzle discharge hole 10a intersects with the peripheral surface of the impression cylinder 5 is desirably set so as to be shifted downstream by, for example, several millimeters from the imaging point. Therefore, as described above, when the air blowing is stopped when the end of the image has passed the imaging point, the printed sheet a is released from the presser by the air and comes into contact with the tip of the pipe 15 of the nozzle device 10, so that the print stains are removed. May occur. Therefore, if the air blowing is continued until the rear end of the sheet printed material a passes through the air blowing position, the occurrence of such printing stains can be prevented.

  Next, the operation of the sheet-fed printed matter inspection apparatus having the above configuration will be described.

  (1) A sheet printed matter a such as a sheet printed on a single-color or multi-color by a sheet-fed printing machine is inspected for quality on the impression cylinder 5 of the final printing unit 1 as shown in FIG. The

  (2) When it is detected from the signal from the rotary encoder 5a that the trailing edge of the sheet printed material a has passed the nip point p, an ON signal is sent from the sequencer 21 to the electromagnetic valve 19, and the electromagnetic valve 19 is opened. Then, air is sent to the nozzle device 10, and air is discharged from each air discharge nozzle 10a. The printed sheet a is pressed against the impression cylinder 5 by the discharged air and is in close contact with the peripheral surface of the impression cylinder 5.

  As a result, the printed sheet a is in close contact with the peripheral surface of the impression cylinder 5, and the camera 12 can scan the printed image for proper imaging.

  (3) On the other hand, light is irradiated from the illuminating device 11 to the part where the printed sheet a is in close contact with the peripheral surface of the impression cylinder 5, and the reflected light travels under the step 9 toward the reflecting mirror 14.

  Thus, since the reflected light passes under step 9 instead of step 9, even if operator b gets on step 9, the reflected light is not blocked by operator b. Accordingly, erroneous recognition of the print quality determination device 13 is eliminated, and an appropriate total inspection of the sheet printed matter a is possible.

  (4) The reflected light by the above scanning is reflected by the reflecting mirror 14 and then passes through the optical duct 17 and reaches the camera 12. The camera 12 receives the reflected light, captures a printed image of the sheet printed material a, and transfers it to the print quality determination device 13.

  Since the optical path from the reflecting mirror 14 to the camera 12 is covered with the optical duct 17, the powder ejected from the powder spraying device 8 is prevented from entering the optical path. For this reason, an appropriate image is picked up by the camera 12, and erroneous recognition of the print quality determination device 13 is prevented.

  (5) When it is detected by the signal from the rotary encoder 5a that the end of the printed image of the sheet printed material has passed the imaging point, an OFF signal is sent from the sequencer 21 to the electromagnetic valve 19, and the electromagnetic valve 19 is closed. Thus, the supply of air to the nozzle device 10 is stopped.

  The supply of air may be stopped after the rear end of the sheet printed material a has passed the front end of the pipe 15 of the nozzle device 10.

  The supply of air is stopped until the trailing edge of the subsequent printed sheet a passes the nip point p. When the nip point p is passed, the supply of air is resumed.

  In this way, air is discharged from the nozzle device 10 after the trailing edge of each printed sheet a passes through the nip point p, and then until the end of the printed image passes through the imaging point or air blowing point, and otherwise. In this case, since the discharge of air is stopped, the excess air does not flow toward the blanket cylinder 4 or the plate cylinder 3 or the flow amount is remarkably reduced. Accordingly, drying of the ink and dampening water on the surfaces of the blanket cylinder 4 and the plate cylinder 3 is prevented, and deterioration of the printing quality is prevented.

  (6) Thus, a print image is properly captured by the camera 12, and the print image is sent to the print quality determination device 13 and inspected by pattern matching to determine whether print quality is appropriate.

  (7) The sheet printed matter a inspected by the printing quality determination device 13 is conveyed to a stacking unit (not shown) by the endless chain 7 of the delivery unit 2 and stacked in a bar. The sheet printed matter a determined to be a defective product by the print quality determination device 13 is displayed as a defective product by sticking a tape with a tape applicator (not shown), for example, when stacking bars.

  In addition, this invention is not limited to the said embodiment, A various change is possible.

  Defect inspection at a printing speed of 11,000 sheets / hour on a 0.13-mm thick A1 printing paper using a Heidelberg sheet-fed duplex printing machine as a sheet-fed printing machine and a speed master SM102 as a printing quality judgment device A test pattern was printed.

  Further, compressed air (static pressure: 3.0 kPa) was supplied to the nozzle device using the compressor as an air source. As the nozzle device, a φ10.8 mm cylinder with holes arranged at equal intervals in one row is used, and this is installed at a position of 40 mm in height from the surface of the impression cylinder while keeping the angle with the camera optical axis at 20 degrees. Air was blown toward the imaging point.

  An electromagnetic valve was provided immediately before the nozzle device, and air was blown from the nozzle device to the printed sheet by opening and closing the electromagnetic valve controlled based on a signal synchronized with the rotation angle of the impression cylinder by the encoder.

  When the detection performance was evaluated by the printing quality determination device, it was confirmed that no erroneous detection occurred from the front end to the rear end in the flow direction of the sheet printed matter, and the defect detection ability was uniform and effective in preventing paper floating.

  Further, no air flow was generated toward the blanket cylinder or the plate cylinder, and printing defects due to drying of the ink layer and fountain solution did not occur.

DESCRIPTION OF SYMBOLS 1 ... Final printing unit 3 ... Plate cylinder 4 ... Blanket cylinder 5 ... Impression cylinder 10 ... Nozzle device 11 ... Illumination device 12 ... Camera 13 ... Printing quality determination apparatus a ... Sheet-fed printed matter p ... Nip point

Claims (1)

An air spraying means for pressing the printed sheet onto the peripheral surface of the impression cylinder in the final printing unit of the sheet-fed printing machine, and a sheet disposed upstream of the air spraying means and pressed against the peripheral surface of the impression cylinder by the air spraying means Illuminating means for irradiating light to the leaf printed matter, a camera for capturing an image of the sheet printed matter illuminated by the illuminating means on the upstream side of the air blowing means, and printing for determining whether printing is good or not from the image photographed by the camera In the sheet printed matter inspection apparatus provided with the pass / fail judgment means, the air blowing from the air blowing means can be turned on and off, and the rear end of the sheet printed matter is between the impression cylinder and the blanket cylinder in contact with the impression cylinder. Turn on the air blow when passing through the nip point, turn off the air blow after the imaging of the printed image of the sheet-fed print is completed,
The air blowing is continued until the rear end of the sheet printed material passes through the air blowing position from which the air is blown after the imaging of the printed image of the sheet printed material is completed,
The sheet-fed printed matter inspection apparatus, wherein the air blowing position is downstream of an imaging point by the camera .

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