JPH0412228B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a printed matter inspection device for in-line comparing the condition of a printed matter being printed with a standard state in a printing press to detect abnormalities in the printed matter.

[Technical background of the invention and its problems]

Conventionally, the mainstream method has been to inspect printed matter off-line, relying on human vision. This stems from the fact that each piece of printed matter has a different pattern, and because inspection items for printed matter have been thought to involve subtle differences that require reliance on human vision. On the other hand, in response to the desire to evaluate printed matter while it is being printed, attempts have been made to use strobe lighting that is synchronized with the printing speed and to use mirrors that rotate synchronously at high speed to judge printed matter that is being printed as a still image. It was done. However, these methods were not systems that could be called inspection machines in that they relied on human vision for inspection. In addition, attempts have been made to print color patches at the same time as the patterns on the printed matter and inspect the color patches, thereby allowing the inspection of the printed matter to be performed on behalf of the user. However, with this method, if printing defects (oil drips, stains, etc.) occur in the pattern area, they will be overlooked, and the inspection machine cannot be said to perform its function satisfactorily.

On the other hand, a system has recently been proposed in which printed matter is inspected in-line using a line sensor, as seen in Japanese Patent Application No. 57-220515 titled "Print Inspection Apparatus." By using this method, the pattern itself of the printed matter can be automatically inspected in-line, so it does not have the above-mentioned drawbacks and can be expected to have excellent effects as an inspection machine. However, the above invention is not without its problems. For example, in a case where a printed matter inspection device is installed in a sheet-fed printing machine, the method of transporting printing paper in a sheet-fed printing machine is such that only the leading edge of the printing paper is gripped with a claw. Just fix it
Since the trailing edge of the printing paper is completely free, the positional relationship between the detection unit in the print inspection device and the inspection surface of the printing paper becomes unstable, which causes a problem in which the accuracy of inspection decreases. It has been considered difficult to apply the above system to sheet-fed printing presses. This problem will be explained in more detail with reference to FIG. 4, which is an explanatory diagram showing the conveyance state of printing paper in a sheet-fed printing machine.

In FIG. 4, the printing paper 1 conveyed from the paper feed section (not shown) is placed on the gripping claw 5 provided on the impression cylinder 2.
The front end of the paper is bitten by the rotation of the impression cylinder 2, and the paper is transferred to the gripping claw 5 provided on the transfer cylinder 6, and the paper is conveyed by the rotation of the transfer cylinder 6, which are repeated. transported to.

When the printing paper 1 passes between the impression cylinder 2 and the rubber side 3 during transportation, it is under pressure, and the ink that has been transferred from the plate cylinder 4 to the rubber cylinder 3 on its surface is transferred onto the printing paper 1. Printing becomes possible by pressure bonding. In reality, in multicolor printing, a predetermined printed product is obtained by repeating the above steps in a plurality of printing units. Incidentally, since printed matter inspection is normally performed at the time when printing is completed, the proper mounting location for the printed matter inspection device is after the final printing unit 7. In a sheet-fed printing press, the possible mounting locations that meet this condition are:
It is conceivable that the printing paper 1 is being conveyed by the gripping claws on the chain 9 (arrow B section) or when the printing paper 1 is being stacked up at the paper discharge section (arrow C section), but in reality, There are many problems due to the influence of the powder to prevent ink from running behind and the instability of chain conveyance, so inspection is performed at the rear and upper part of the final impression cylinder 8 (arrow A part), which corresponds to immediately after printing in the final printing unit. is considered to be the most appropriate. There is also a method of installing a unique inspection unit next to the printing unit, but this requires large-scale equipment and is problematic in terms of cost. Now, considering the inspection at the rear upper part of the final impression cylinder 8 (arrow A part), it is only necessary to install the detection part of the print inspection device (for example, the illumination light source and camera unit) at that position, so it is space-saving. No problem. However, some printing machines have even more limited space, and in that case, the problem of mounting space can be overcome by using means such as optical fibers or contact type line sensors. However, when inspecting printed matter at the arrow A section, there are the following problems. That is, while the front end of the printing paper 1 is bitten by the gripper and the impression cylinder and blanket cylinder are applying printing pressure to a part of the printing paper, the printing paper 1 is held tightly against the impression cylinder. Because the printing paper is in close contact with the impression cylinder, the relative position of the input information in pixels during inspection is stable. It is fixed with a claw or a biting claw on the chain,
If the other parts of the printing paper are completely free, the trailing edge of the printing paper will become unstable and will not come into close contact with the impression cylinder 8 and will float up or exhibit phenomena such as waving, making accurate inspection impossible. Get into an impossible situation.

Here, if the printing paper is limited to thin paper with a paper thickness of about 0.1 m/m, an air blowing port 10 is provided above the final impression cylinder 8 as shown in FIG. The above-mentioned problem can be solved by blowing air in a direction that brings the printing paper 1 into close contact with the final impression cylinder 8. However, for thick paper with a paper thickness of more than about 0.3 m/m, the printing paper 1 cannot be brought into close contact with the final impression cylinder 8 by air blowing. is not possible. For this reason, when using thick paper, the trailing edge of the printing paper will jump up, and the image information taken in from the detection unit of the print inspection device will be unstable near the trailing edge of the printing paper, making it impossible to perform the desired inspection. Become. In order to solve this problem, the present applicant has filed Japanese Patent Application No. 134814/1983 for ``Printed material inspection device''.
proposed that a paper holding mechanism be attached to the detection system. According to this paper pressing mechanism, the printing paper can be brought into better contact with the impression cylinder compared to the above-mentioned method using air blowing, but since it presses the left and right margins of the printing paper, it is difficult to print. A lifting phenomenon may occur in the center of the paper, and as the size of the printing paper increases, this phenomenon becomes more noticeable, making it difficult to ensure accurate inspection.

[Purpose of the invention]

The present invention has been made to solve the above-mentioned problems, and enables accurate inspection of printed matter by reliably preventing inspection-inhibiting factors such as bounce of the trailing edge of printing paper in sheet-fed printing machines, and improves operability. The purpose of this invention is to provide an excellent printed matter inspection device.

[Summary of the invention]

The present invention is installed in a sheet-fed printing machine, captures image information of a pattern on a printed matter pixel by pixel, and compares the detected image signal of each pixel with a reference signal of the corresponding pixel to inspect the printed matter for abnormalities. In the inspection device, multiple paper press rollers are moved and positioned to arbitrary positions, and the paper press rollers are pressed onto the final impression cylinder in accordance with the passing timing of the sheet to be inspected, and the paper press rollers are positioned. This is a printed matter inspection device equipped with a paper holding device that uses a graphic display.

[Detailed description of the invention]

The present invention will be described below based on embodiments shown in the drawings. Fig. 1 shows one of the printed matter inspection apparatus of the present invention.
This is an explanatory diagram of an embodiment, and the printing paper 1 is inspected while being in close contact with the rotating final impression cylinder 8 with its front end fixed by the claw 5 on the final impression cylinder 8. As mentioned above, the trailing edge of the printing paper 1 becomes free when it is released due to the contact pressure between the blanket cylinder 3 and the final impression cylinder 8 for printing. Therefore, it is pressed against the final impression cylinder 8, and close contact with the impression cylinder 8 is maintained. The operation of this paper holding mechanism 14 is controlled by the CPU 16, but the details will be explained in the second section.
This will be explained later based on the figures.

Here, to explain the outline of the inspection, the printing paper 1 is illuminated by the reference 13, and the image information of the reflected light from the pattern printed on the printing paper 1 is collected from the input camera 11 consisting of a CCD camera or the like. Capture as signal IS. The start timing and sampling timing of signal acquisition by this input camera 11 are controlled by a pulse generator 12 attached to the final impression cylinder 8 (or plate cylinder, bracket cylinder, etc.).
The CPU 16 performs control based on the timing pulse TP. The input image signal IS is digitized by the A/D converter 15, and the image signal when the operator determines that the print is normal is stored in the reference memory 19 as a reference signal, and the inspection of the print is performed on future prints. This is executed by comparing the image signal of 2 with this reference signal in the CPU 16. The method of comparative inspection is differential,
There are processes such as differentiation and integration, which can be applied as appropriate, and a printed matter whose error from a normal printed matter is not within an allowable range is determined to be an abnormal printed matter. In such processing, if high-speed processing is required due to the relationship between printing speed and amount of information, a method of performing the above processing using a hardware configuration is suitable. If it is determined that the printed matter is abnormal as a result of the comparative inspection,
An abnormality is displayed on the graphic display 18. Other means, such as rejecting abnormal printed matter or marking it, may also be used. In reality, it is necessary to input auxiliary information such as changing the inspection standard according to the required quality of the printed matter or setting up an inspection area and a non-inspection area in the field of view of the input camera 11. Since it is necessary to instruct the start of the inspection, the input board 17 is connected to the CPU 16, and the input board 17 issues instructions for the above-mentioned work.

When inputting the position of the paper presser roller of the paper presser mechanism 14 from the input board 17, the position of the paper presser roller is determined in correspondence with the pattern on the graphic display 18. FIG. 3 is an example of a pattern printed on cardboard with an actual paper thickness of 0.3 m/m or more. As shown in FIG. 3, most of the patterns 120 printed on the printing paper 1 are printed on multiple sides of the same pattern in printed materials made of thick paper, and the margins 121 are not only at the left and right edges of the paper, but also at the edges of the paper. A margin portion 121 also exists inside the paper 1 along the paper flow direction D.

For this reason, the paper presser roller 10 is placed in the margin portion 121.
If a plurality of 1 are prepared and the crimping operation against the impression cylinder is made possible, better inspection will be possible.

Here, it is best if there are as many paper presser rollers 101 as there are blank spaces in the paper flow direction, but it is also possible to have at least three or more paper presser rollers 101. (There are five in Fig. 3.) The position of this paper presser roller 101 can of course be changed by changing the size of the printing paper 1 or by changing the imposition of the pattern 120 to be printed. Must.

For this reason, it is preferable to display the state of the pattern 120 on the printing paper 1 on the graphic display 18 and move the cursor according to instructions from the input board 17 to determine the position of the paper presser roller 101.

That is, by pressing the cursor movement command key from the input board, the position information of the margin section 121 in the flow direction is sent to the CPU 16, and the paper presser roller 101 of the paper presser mechanism 14 is moved to the desired position.

Further, other input means such as a digitizer may be used in place of the input board, but interaction with the graphic display 18 is preferable.

Next, referring to FIG. 2, a more detailed explanation will be given of the paper holding mechanism 14, which is a feature of the present invention that enables more accurate inspection.

FIG. 2 is a front view of one embodiment of the paper holding mechanism in the printed matter inspection apparatus of the present invention. The entire paper holding mechanism is attached to the printing press body using two jigs 109. A pair of air cylinders 108 and a guide shaft 110 are each fixed on the jig 109, and the support stand 10 is moved by driving the air cylinders 108.
7 is movable up and down along the guide shaft. As shown in FIG. 1, when this mechanism presses the paper presser roller 101 against the final impression cylinder 8 to prevent the trailing edge of the printing paper 1 from bouncing up, it may become stuck if contact pressure is constantly applied. The claw 5 and the paper presser roller 101 may collide with each other, so this is provided to prevent such a situation from occurring. With this mechanism, the gripper claw 5 passes the position of the paper presser roller 101, and while the printing paper 1 is being pressurized by the final impression cylinder 8 and the blanket cylinder 3, the paper presser roller 101 is held perpendicular to the final impression cylinder. The printing paper 1 waits at the top, and immediately before the rear end of the printing paper 1 comes out of the pressure position and becomes free, the printing paper 1
It becomes possible to contact and apply pressure to the object.
Also, during printing (that is, during pressurization between the final impression cylinder 8 and blanket cylinder 3), the paper presser roller 10
1 to the printing paper 1, it may cause a printing failure (so-called shot stitch), and after the trailing edge of the printing paper 1 becomes free, the above-mentioned problem occurs, and the input camera 11 Because the input image information becomes unstable, the paper presser roller 1 is moved immediately before the trailing edge of the printing paper becomes free, as described above.
01 is lowered and pressurized.

The pressing of the paper presser roller 101 can be released by lifting the support stand 107 after the rear end of the printing paper 1 has passed under the paper presser roller 101 and before the gripping claw 5 arrives again.

The timing of pressing and releasing the paper presser roller 101 due to the movement of the support base 107 by the air cylinder 108 is determined by inputting the size of the printing paper 1 from the input board 17 using the picture on the graphic display 18 in advance. The solenoid valve for the air cylinder 108 can be controlled by counting the timing pulse TP of the pulse generator 12. As described above, the entire support base 107 can be moved up and down while timing the printing paper 1 to be pressed onto and released from the impression cylinder 8.

The mounting position of the paper presser mechanism 14 is set so that the crimping position by the paper presser roller 101 is as close as possible to the signal acquisition line of the input camera 11 without interfering with signal acquisition for inspection. This makes it possible to keep the printing paper 1 pressed against the impression cylinder 8 until all the patterns on the printing paper have been inspected. In addition, support stand 1
Multiple pieces below 07 (more than 6 pieces (i.e. 3 sets))
A bracket 111 is fixed, and a drive screw 103 and a guide 104 are provided between each two brackets 111, and the drive screw 103 is rotated by a motor 105 fixed to the outer bracket 111. I can do it. On the other hand, the roller support 1 is fitted with the drive screw 103 through the thread groove.
02 is also fitted in a groove in the guide 104, so by rotating the drive screw 103, the roller support 102 can be moved in parallel along the guide 104. Further, a paper presser roller 101 is rotatably held below the roller support 102, and as a result, the paper presser roller 101 can be moved in parallel in the axial direction of the final impression cylinder 8. This is because ink stains occur when the pattern area of the printed material is pressed, so the image 120 cannot be printed on the entire surface of the printing paper 1 as shown in FIG.
1 are located at several places on the left and right ends and in the center of the printing paper 1.
Therefore, depending on the size of the printing paper 1 and the position of the image, press the paper presser roller 10.
This is because it becomes necessary to change the position of 1. The paper presser roller 101 is located at the front input board 1.
According to the size of printing paper 1 input from 7,
This can be determined by counting the pulses of the encoder 106 and rotating the motor 105. With such a configuration, it is possible to prevent the rear end of the printing paper 1 from jumping up from the final impression cylinder 8, and stable inspection becomes possible.

Note that in the paper press mechanism of the embodiment shown in FIG. 2, the central portion is omitted, and paper press rollers 101 are actually arranged in the omitted portion with the same configuration as the others.

The above is an outline of one embodiment of the paper presser mechanism, but of course it would be more effective to provide an adjustment screw, a stopper, etc. as a mechanism for adjusting the contact pressure of the paper presser roller 101 and the amount of movement by the air cylinder 108. However, there is no problem with using other drive systems or adjustment mechanisms as long as they have a structure that exhibits similar effects.

〔Effect of the invention〕

As described above, the print inspection device of the present invention has the paper holding mechanism, thereby making it possible to perform in-line print inspection on a sheet-fed printing press, which has been extremely difficult in the past. By preventing the trailing edge of the printing paper from bouncing, inspection can be stabilized.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing one embodiment of the printed matter inspection device of the present invention, FIG. 2 is an explanatory diagram of one embodiment of the paper holding mechanism of the printed matter inspection device of the present invention, and FIG. 3 is an explanatory diagram showing one embodiment of the printed matter inspection device of the present invention. FIG. 4 is an explanatory diagram showing the state of paper;
The figure is an explanatory diagram showing the conveyance state of printing paper in a sheet-fed printing machine, and FIG. 5 is an explanatory diagram of a method for stabilizing the conveyance of printing paper by air blowing. 1... Printing paper, 101... Paper press roller, 3... Rubber cylinder, 103... Conveyance screw, 5... Biting claw, 105... Motor, 8... Final impression cylinder, 108... Air cylinder, 11... Input camera, 14... Paper Presser mechanism, 16
...CPU, 18...Graphic display.

Claims (1)

[Claims] 1. Installed in a sheet-fed printing machine, it captures image information of the pattern of printed matter pixel by pixel, and compares the detected image signal of each pixel with the reference signal of the corresponding pixel to detect abnormalities in the printed matter. In a print inspection device that inspects printed matter, a detection system including an input camera for capturing image information of the pattern of the printed material can capture image information of the pattern of the printed material on the impression cylinder immediately after printing is completed in the final printing unit of the printing press. A paper holding mechanism is provided between the printing position of the final unit and the position where image information of the pattern of the printed matter is captured, and the paper holding mechanism presses the printed matter onto the impression cylinder, and the paper holding mechanism is connected to the support base and the support base. a plurality of paper holding rollers that are movable in parallel at least in the axial direction of the impression cylinder; adjustment means for moving the paper holding rollers to a desired position; and movement of the entire support stand in a direction toward and away from the impression cylinder. A printed matter inspection apparatus comprising: a driving means for controlling the adjusting means and the driving means; and an input means for inputting position information of the paper holding roller. 2. The printed matter inspection apparatus according to claim 1, wherein the input means includes a graphic display.