JPH0576908B2 - - Google Patents

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a defective printed matter detection device that determines the quality of printed matter on the plate cylinder side, and is particularly useful when applied to intaglio printing machines. It is.

<Prior Art> FIG. 3 is an explanatory diagram conceptually showing an intaglio printing press according to the prior art. As shown in the figure, papers 3 to be printed matter are stacked on a paper stacking table 2 of a paper feeder 1, and are sucked one by one and sent onto a conveyor belt 4. Swing device 5 that swings with a cam mechanism
has gripping claws, grips the paper 3 that has been conveyed on the conveyor belt 4 to its downstream end, and conveys it by the swing angle. This paper 3 is supplied to the impression cylinder 6 via the paper transfer cylinder 7. That is, the outer circumference of the impression cylinder 6 is
Gripping claws 8 and 9 are provided at the equal parts and at one location on the outer periphery of the paper transfer cylinder 7, respectively, so that they face each other sequentially as the impression cylinder 6 and the paper transfer cylinder 7 rotate. The paper 3 held in the device 5 is transferred to the holding claw 8 via the holding claw 9 and wound around the circumferential surface of the impression cylinder 6.

A sprocket 10 is disposed on the opposite side of the paper transfer cylinder 7 with respect to the impression cylinder. Further, a paper discharge chain 13 is suspended between this sprocket 10 and a sprocket 12 disposed near the paper stacking table 15. A plurality of (four in the figure) paper ejection gripping claws 14 are arranged at regular intervals on the paper ejection chain 13, and the intaglio-printed paper 3 is held between the impression cylinder 6 and the intaglio cylinder 16. The ejected paper is transferred from the claw 8 to the gripping claw 4 and conveyed. The paper stacking table 15 is connected to the paper ejection chain 1
It is located below the downstream end of the paper 3, and after being conveyed to the end, the paper 3 that is released from the ejected paper holding claw 14 and falls is received and stacked.

An intaglio cylinder 16 having the same diameter as the impression cylinder 6 is equipped with a plurality of intaglio plates 17 (three in the figure) at equal intervals, and each intaglio cylinder 16 has a pattern of the object to be printed as a concave image area. It is formed.

The surface of the intaglio 17 of the intaglio cylinder 16 is in contact with the circumferential surface of a plurality of pattern rollers 18 (three in this example as it is for three-color printing) each having a diameter of approximately 1/3 of the intaglio cylinder 16. There is. Convex portions (not shown) corresponding to the patterns of each color are formed on the circumferential surface of the pattern roller 18, and the ink of each color in the ink pot 22, which is deposited via the pot roller 19, is transferred to the convex portion. The intaglio plate 17 is supplied through the intaglio plate 17. At this time, each of the convex portions is formed to be one size larger than the corresponding concave image portion of the intaglio plate 17, and portions other than the convex portions are relatively concave portions that do not come into contact with the intaglio plate 17.

A wiping roller 2 rotating in the same direction as the intaglio cylinder 16 is provided diagonally below the intaglio cylinder 16, that is, downstream of the pattern roller 18 with respect to the rotational direction of the intaglio cylinder 16.
6 are in contact with each other, and this wiping roller 26
Excess ink adhering to the surface of the intaglio plate 17 is wiped off. A wiping tank 28 having a plurality of brushes 29 and storing cleaning liquid 27 is disposed below the wiping roller 26 . At this time, wiping roller 2
The cleaning liquid 27 adhering to 6 is scraped off by the doctor blade 30.

In printing using the above-mentioned intaglio printing machine, defective printed matter may occur during printing due to dust or the like adhering to non-image areas. For this reason, until recently,
Workers were checking each printed page one by one.

In order to streamline such checking work, an image of a reference printed matter is captured as reference image data using an image processing means having an optical imaging system, and then an image of the printed matter to be inspected is captured using the same image processing means. An apparatus has been developed that automatically detects defective printed matter by comparing the image data of the image data with the reference image data.

Such defective printed matter detection device includes a CCD camera,
It consists of an imaging means such as a line sensor, a signal processing circuit that processes the electrical signal that is the output signal of this imaging means, and a rotary encoder that supplies a reference signal for processing to this signal processing circuit. A device that determines the quality of printing by comparing the levels at corresponding positions with the image data of the printed matter to be inspected, and determining whether or not the level difference between the two is within a predetermined value. It is.

<Problems to be Solved by the Invention> Incidentally, the defect detection apparatus according to the prior art has the following drawbacks because the image data for inspection is obtained from the finished printed matter.

(1) When the paper 3, which is a printed matter being conveyed on the paper ejection chain 13 shown in FIG. Since only the tip of the paper 3 is held in the mouth, the paper 3 flaps during transportation, so a new mechanism must be installed to prevent the paper 3 from flapping, which increases the cost of the machine. .

(2) As shown in FIG.
For example, attach three intaglios 17 with the same design,
When printing multiple sheets per rotation of the intaglio cylinder 16, it is necessary to accurately align the mounting position of the intaglio plate 17 with respect to the intaglio cylinder 16 so that the relative position of the pattern on the intaglio plate 17 is constant. Since the work is done by humans, errors do occur. Therefore, it cannot be applied in this case.

In view of the above-mentioned prior art, the present invention is capable of accurately detecting defective printed matter, and even when printing by attaching a plurality of plates with the same pattern to a plate cylinder, it is possible to detect defective printed matter in the same way regardless of the error in attaching the plates. It is an object of the present invention to provide a defective printed matter detection device that can accurately detect defective printed matter.

<Means for Solving the Problems> The present invention, which achieves the above object, is a defective printed matter detection device that determines whether the finished printed matter is good or bad after being printed by a printing machine. an imaging device that captures an image of the state of the surface of the printing plate, a position detection sensor that detects the rotational position of the plate cylinder, and a reference image data of the surface of the printing plate captured by the imaging device at the start of printing and the print plate captured by the imaging device at the time of printing. It has a signal processing circuit that compares the determination image data of the plate surface in correspondence for each corresponding pixel based on the signal from the position detection sensor and determines whether the level difference between the two is within a predetermined range. , an imaging means for capturing an image of the surface condition of each of the plurality of printing plates each having a pattern to be printed formed thereon and mounted on the plate cylinder; a position detection sensor for detecting the rotational position of the plate cylinder; Each standard image data of the surface of each printing plate, respectively captured by the imaging means at the start, and each determination image data of the surface of the printing plate, respectively captured by the imaging means at the time of printing, are compared in correspondence based on the signal from the position detection sensor. The present invention is characterized by comprising a signal processing circuit that determines for each printing plate whether or not the level difference between the two is within a predetermined range.

<Function> According to the present invention having the above configuration, the quality of printed matter is determined based on image data representing the condition of the surface of the printing plate.

Furthermore, when there are a plurality of printing plates, the above determination is performed for each printing plate.

<Examples> Examples of the present invention will be described in detail below based on the drawings. This embodiment is applied to an intaglio printing machine in which three intaglio plates with the same pattern are attached to an intaglio cylinder. Therefore, the same parts as in FIG. 3 are given the same numbers and redundant explanations will be omitted.

As shown in FIG. 1, a CCD camera (hereinafter simply referred to as a camera) 31 serving as an imaging means is mounted on the intaglio cylinder 16 so as to take an image of the surface of the intaglio 17 after the ink has been wiped off by the wiping roller 26. The lenses are disposed so as to face each other on the surface of the concave portion 17 on the downstream side of the wiping rower 26 with respect to the rotation direction (counterclockwise in the figure). Signal processing circuit 3
2 processes an electrical signal which is an output signal of the camera 31, the details of which will be described later. The rotary encoder 33, which is a position detection sensor, is connected to the intaglio cylinder 1.
6 and supplies rotational position information of the intaglio cylinder 16 to the camera 31 and the signal processing circuit 32.

FIG. 2 is a block diagram showing this embodiment. As shown in the figure, the camera 31 includes an optical system such as a lens 34 and a CCD 35 that converts an image line formed through the optical system into an electric signal corresponding to the image line.

The signal processing circuit 32 is a portion surrounded by a chain double-dashed line in the figure. In this embodiment, the reference memories 36 No. 1 to No. 3 read and store the reference image data for each intaglio plate 17 individually in correspondence with the three intaglio plates 17.
a, 36b, and 36c, and similarly, No. 1 to No. 3 detection memories 3 that individually read and store judgment image data for quality judgment for each intaglio 17.
It has 7a, 37b, and 37c. The memory controller 38 controls reading of data into the reference memories 36a to 36c and the detection memories 37a to 37d. The judgment level setting circuit 39 sets in advance an allowable level difference between reference image data and judgment image data. The comparator 40 compares the reference image data and the judgment image data, and when the level difference between the two is greater than or equal to the allowable level difference set in the judgment level setting circuit 39, it sends out a signal representing this fact. That is, by comparing the reference image data corresponding to each pixel of the CCD 35 and the judgment image data one by one, the levels of both data corresponding to each pixel are compared, and if even one of the data exceeds the allowable level difference, the signal is Send out. Correction circuit 41
The amplifier 42 is adjusted in accordance with the rotation speed of the intaglio cylinder 16.
This is to adjust the gain of. Even if the same amount of light enters the camera 31, the faster the rotation speed of the intaglio cylinder 16, the lower the output signal level of the CCD 35.
A correction circuit 41 is provided to correct the influence of rotational speed. In the figure, 43 is a CCD controller, and 44 is an A/D converter.

A signal processing circuit 32 consisting of each of these blocks
is controlled by the following signals. That is, the phase signal is the output signal of the rotary encoder 33,
A reference signal which is a pulse signal that rises at every rotation of the intaglio cylinder 16 (the starting position of the first intaglio plate 17, the reference position) and a pulse signal for reading and writing data that rises at every constant rotation of the intaglio cylinder 16 The memory controller 3 also consists of a clock pulse.
8. Judgment level setting circuit 39, correction circuit 41 and
The signal is supplied to the CCD controller 43. The reference value memory signal is a signal for reading the reference image data in the reference memories 36a to 36c via the memory controller 38, and is supplied by turning on a switch (not shown). The determination start signal is a signal for starting the comparison between the reference image data and the determination image data, and is supplied by turning on a switch (not shown). The judgment accuracy operation signal is a signal for adjusting the preset value in the judgment level setting circuit 39, that is, the value of the allowable level difference. The step signals are address signals for the reference memories 36a-36c and the detection memories 37a-37c.

In this embodiment, first, the operator visually checks the condition of the actually printed material while performing trial printing, determines whether it is good or bad, and if it is good, sends out a reference value memory signal. Thereafter, a reference signal representing the reference position is transmitted to the rotary encoder 33.
At the time when the reference image data is sent from the first intaglio 17, the reference image data is read into the first reference memory 36a. This reading continues until it is detected by the clock pulse of the rotary encoder 33 that the position corresponding to the notch in the intaglio cylinder 16 has been reached. Next, when it is detected that the starting position of the second intaglio 17 has been reached, reading of the reference image data is started again, and this reference image data is stored in the second reference memory 36b. Image data for the third intaglio 17 is also stored in the third reference memory 36c using the same procedure. After the reference image data of the surface of each intaglio 17 is stored in the first to third reference memories 36a to 36c in this manner, a predetermined determination process is started by a determination start signal. This process is performed in exactly the same manner as when reading the reference image data, and as the intaglio cylinder 16 rotates, the intaglio 17 corresponding to the first to third detection memories 37a to 37c, respectively,
By reading judgment image data on the surface of the image data and comparing each judgment image data with the corresponding reference image data, it is judged whether or not the level difference between the two is within the allowable level difference. In this way, defects in printed matter can be detected.

Incidentally, in intaglio printing, after ink is supplied to the intaglio plate 17, excess ink is wiped off by the wiping roller 26.
On the surface of the intaglio plate 17 on the more downstream side, ink remains only in the concave portions that form the pattern, and this ink is transferred to the paper 3. On the other hand, most of the stains that occur during printing are caused by the wiping roller 26 not being able to wipe off excess ink from the convex portions on the surface of the intaglio 17. Therefore, the condition of the surface of the plate 17 after wiping off the excess ink with the wiping roller 26 can be considered to be the same as the condition of the printed matter.

<Effects of the Invention> According to the present invention, as specifically explained in conjunction with the embodiments above, the quality of printed matter is determined by observing the condition of the surface of the printing plate. Compared to the case where printing is carried out, it is possible to accurately judge whether the printed material is good or bad without being affected by the state of the printed material at the time of judgment, such as the flapping of the printed material during transportation. Furthermore, in the present invention, even when a plurality of printing plates are attached to one plate cylinder, reference image data and judgment image data are matched and compared for each printing plate, so that the plate cylinder of the printing plate is It is possible to accurately judge the quality of all printed matter without being affected by the mounting condition on the paper.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram conceptually showing the entire embodiment of the present invention, FIG. 2 is a detailed block diagram thereof, and FIG. 3 is an explanatory diagram conceptually showing an intaglio printing machine according to the prior art. In the drawing, 16 is an intaglio cylinder, 17 is an intaglio plate, and 31 is an intaglio cylinder.
A CCD camera, 32 a signal processing circuit, and 33 a rotary encoder.

Claims (1)

[Scope of Claims] 1. In a defective printed matter detection device for determining the quality of printed matter produced by a printing press, an imaging means for capturing an image of the state of the surface of a printing plate on which a pattern to be printed is formed and mounted on a plate cylinder. , a position detection sensor that detects the rotational position of the plate cylinder, and a position detection sensor that detects the reference image data of the surface of the printing plate captured by the imaging means at the start of printing and the judgment image data of the surface of the printing plate captured by the imaging means at the time of printing. What is claimed is: 1. A defective printed matter detection device comprising: a signal processing circuit that compares each corresponding pixel based on a signal from the pixel and determines whether a level difference between the two is within a predetermined range. 2. In a defective printed matter detection device that determines the quality of printed matter produced by a printing press, images are taken of the surface condition of each of a plurality of printing plates each having a pattern to be printed and each mounted on a common plate cylinder. a position detection sensor that detects the rotational position of the plate cylinder; reference image data of each printing plate surface captured by the imaging device at the start of printing; and reference image data of each printing plate surface captured by the imaging device at the time of printing. A signal processing circuit that compares the judgment image data for each corresponding pixel based on the signal from the position detection sensor and determines for each printing plate whether the level difference between the two is within a predetermined range. A defective printed matter detection device comprising: