JPS59128419A - Printed material inspecting device - Google Patents

Abstract

PURPOSE:To make it possible to perform flexible, excellent inpsection of a printed material, by comparing two picture data corresponding to repeating picture patterns, and comparing the characteristic parameters of the data of one picture with reference values. CONSTITUTION:The inspecting parts of input parts 100, 200, and the like receive reflected light from a printed material that is conveyed and receives light. The inspecting parts are proportionally separated by the distances from the repeating picture patterns. The color picture data of the parts corresponding to the two picture patterns are compared by comparators 301-303 through the input parts 100 and 200. Unexpected partial defects are detected by the mutual comparison of the picture patterns in a defect detecting part 304. Meanwhile, the color picture data from the imput part 100 are processed by integrators 311- 313 and picture data characteristic patterns are obtained. They are compared with reference values in comparator 317-319. The small changes for every picture pattern are added, and the defect as a whole is detected through a defect detecting part 320. In this constitution, practical, flexible, excellent inspection of the printed material can be performed.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an inspection device for in-line inspecting the quality of printed matter, particularly multicolor printed matter, in a rotary printing press.

In general, the causes and phenomena of poor printing in printed matter are that in offset printing, water or oil adheres to the printing paper during printing, and the ink does not transfer to that area.
The phenomenon of thinning and color fading, or the phenomenon of dirt adhering to the plate cylinder or blanket cylinder, which causes dirt-sized stains to be printed on printed matter, a phenomenon called hiccups, and the problem of water being supplied Typical examples include stains caused by insufficient quantity, and printing shifts due to poor registration in multicolor printing.

There are two methods of inspecting printed matter to detect such printing defects: an indirect inspection method that uses the margins other than the printed image, prints tone marks or color patches there, and inspects this, and Conventionally, a method of directly inspecting the

In the former case, not only is there a need for margins for printing inspection marks and patches on the printed matter, but there are also defects in the pattern that do not appear in the color mark or color batch, such as dirt in the pattern or partial color tone defects. There was a drawback that printing defects could not be detected.

In the latter case, the inspection method is to divide the width direction of the print with multiple inspection devices in the direction of movement of the print, or scan the entire width of the print with a single device, such as a laser beam, and reflect it with a minute spot. When the light is received, an image of the printed matter is connected to a licensor such as a CCD or an image sensor such as an image pickup tube by optical means, and the image of the printed matter is detected.
There are methods of obtaining and inspecting information. However, whichever method is adopted, it is necessary to read and create data serving as a reference for the inspection from the reference printed matter using the input section of the inspection device or an external input device, and to store it in the storage section of the inspection device.

As a result, if we take detailed samples from a printed matter to detect defective prints such as ri-hikki within a few millimeters of the printed matter, or increase the amount of each sampling data to detect subtle changes such as the color tone of the printed matter,
The amount of reference data that should be stored in the storage section of the inspection device is enormous. Moreover, when inspecting at high speed, in order to read the reference data from the storage unit in accordance with the input printed matter data, the memory element of the storage unit must be fast-acting and expensive, and read timing control is required. The configuration of the inspection device becomes complicated.

As an inspection method that does not require a reference data storage unit or associated timing, reading, and writing control unit in such an inspection device, a method that compares the same pattern that is repeatedly printed on printed matter can be considered. . It is possible to detect printing defects by always inputting two separate images from printed matter at the same time and comparing the two. This method eliminates the need for a memory unit for reference data, and improves the quality of printed matter. It is possible to detect printing defects while allowing gradual and small variations within a range that does not cause defects over a long period of time. As a practical example, two consecutive 7 pictures may have slight changes that cannot be detected, and even if the value of each part of the picture changes slightly, when looking at the picture as a whole, there is no change in the tone of the color etc., and it is considered defective. There are some printed materials that should not be printed. When using a method that simply compares with standard data when inspecting printed matter with such characteristics, it has the disadvantage that it is difficult to easily determine the tolerance value from the standard data, but an inspection method that uses pattern comparisons does not. Since minute changes in the pattern are not detected, the above-mentioned variations that cannot be considered as defective printed matter are not detected as defects.

By the way, the variation allowed by the inspection method by comparing patterns does not necessarily mean that it is not a defect, and the condition of the printed product may change completely after minute changes continue and accumulate. must be detected.

Therefore, in addition to the inspection method based on comparing patterns, the printed matter inspection apparatus of the present invention also uses an inspection method that detects a certain characteristic parameter from the pattern of the printed matter and simply compares this characteristic parameter with a reference value. This makes it possible to detect printing defects that occur after a series of minute changes.

Hereinafter, the printed matter inspection apparatus of the present invention will be explained in detail. The printed matter inspection apparatus of the present invention includes a light source that illuminates the printed matter, an optical system that separates the pattern information of the printed material into three colors RG'B and guides it to the printer, and converts the pattern information into electrical signals. A processing system consisting of two sets of input means consisting of sensors, a means for comparing two pieces of pattern information and detecting a difference, and a means for detecting a printing defect from the difference, and a processing system that calculates the characteristic parameters of the pattern and the density of the entire pattern in RGB. A processing system consisting of a means for integrating the RGB density for one side of the pattern information as an integral value, a means for detecting the difference between the integral value and a reference, and a means for detecting a printing defect from the difference, there was a printing defect. This is a device consisting of a means for displaying a case. In the present invention, an array sensor is used as an example of the input means, but a photomultiplier tube, an image pickup tube, etc. may also be used.

FIG. 1 shows a state in which a print inspection device is attached to an offset rotary press as an embodiment of the present invention.

The printing paper (1) is printed using an offset rotary press (1, so black (B),
Indigo (C).

Four colors, red (goods) and yellow (Y), are printed on the front and back, and the paper is inspected after it leaves the final printing unit (3). Since the inspection is performed for each image on one plate of printed matter, a rotary encoder (30) is attached to the blanket cylinder (4) of the final printing unit (3) to notify the input timing of the image on one plate. Rotation pulses R and P are sent to the inspection device (300) in accordance with the rotation of the blanket cylinder (4).

Based on this rotation pulse RP, an input control signal IC is sent from the inspection device (300) to the input device (100) and the input device & (200), and an input corresponding to the moving speed of the printed material is made.

The input devices (100) and (200) are offset rotary presses (
If it has passed through the final printing unit (3) of No. 1, it may be the part where one line in the width direction of the printed matter is visible, but
In order to compare two pictures, it must be set up so that the same position of the picture is always input.

FIG. 2 shows a state in which the input device of the printed matter inspection device inputs a pattern. Input device (ioo) by Arise/Su.

The interval between the inspection lines in (200) is l, but if the pattern for one plate is repeated every distance a on the printing paper (1), then l is an integral multiple of a. In Figure 2, two adjacent pictures are input, but it is also possible to enter a few pictures apart.

Although only the top side of the printing paper (1) is inspected in Figure 1, it is possible to inspect both sides by attaching the print inspection device to the bottom side as well. (20) is printing paper (1)
It uniformly illuminates the inspection line in the width direction.

It is preferable to use a white light source that has a large amount of light and has a long lifespan.Also, since signal processing for inspection may be performed at high speed, the amount of light changes depending on the 50Hz or 60Hz of the commercial power supply, and one line General fluorescent lamps and incandescent bulbs whose light intensity changes during input cannot be used; therefore, use high-frequency driven fluorescent lamps or incandescent electric lamps that emit light from a constant voltage and constant current DC power source. It is preferable.

Here, a schematic configuration of the input devices (100) and (200) is shown in FIG. Input device (100) and input device (120
0) has exactly the same structure. In Fig. 3, the input device (100)
The configuration is explained below. The input device 1 (1,00) is for inputting pattern information regarding the three primary colors of light, RGB, and includes a dichroic mirror (ll'l) to separate the reflected light from the printing paper (1) into RGB wavelength bands. (112
) (113) is provided. A dichroic mirror is a light interference effect created by alternately vacuum-depositing non-absorbing materials with high refractive index and non-absorbing materials with low refractive index on a glass plate and adjusting the film thickness and number of layers to appropriate values. A dichroic mirror that reflects light in a wavelength range and transmits light in other wavelength ranges, for example, a dichroic mirror manufactured by Japan Vacuum Optical Co., Ltd., can be applied to the present invention. The dichroic mirror (111) reflects light in a band corresponding to visible light red R with a wavelength of 6004 nm or more, and transmits light in other bands.
A dichroic mirror (113) is used that reflects light corresponding to green G of 00 mm and transmits light of other bands, and furthermore, the dichroic mirror (113) reflects light of a band corresponding to blue violet B of visible light with a wavelength of 500 mm or less. Use what you do.

Lens (101), (103), (104), (
The optical system composed of 105) and (106) reflects all of the reflected light from the inspection area of the print onto the tiny light-receiving surfaces of each array sensor (121), (122), and (123) so that it can be received. It is provided to condense light and reduce the image of the inspection area at a fixed ratio.

In this way, the reflected light from the inspection area on the printing paper (1) is color separated and focused, and the array sensor (121)
, (122), and (123) and is converted into an electrical signal according to the amount of received light. This electrical signal is sent to the array controller (13) by the input control signal IC sent from the inspection device.
0) outputs a control signal C8, the array sensor (121
).

(122), (123) to RGB inspection signal) Sl
, GSI, and BSI to the inspection equipment.

As an example, an array sensor is used as the input device of the printed matter inspection apparatus of the present invention, but a high-speed transfer, high-sensitivity CCD type photo-sensing array may also be used as the array sensor. A CCD 142 having 2048 elements can be used.

The array sensor scans the printing paper (1) in the width direction, and as the printing paper (1) itself is transported by the printing machine, the surface of the printing paper (1) is sequentially scanned line by line. 0 Next, the outline of the printed matter inspection apparatus is shown in FIG. 4.0 The printed matter inspection apparatus of the present invention processes and inspects pattern information from an input device using two types of methods. One is inspection by mutual comparison of two picture information from two input devices, and this method allows inspection without providing a section for storing reference picture information. The other is that it is possible to detect abnormalities caused by the accumulation of minute changes in the color and density of the entire pattern, which cannot be detected by the inspection method using pattern information from one of the input devices.

The processing system for mutual comparison includes comparators (301), (39
2).

(303) and a defect detector (304). Input device 1
RGB inspection signals R8I, GSI, from (100)
RGB test signal R from BSI and input device 2 (200)
82, GS2. BS2 has a comparator (301
), (302), and (303), and their RGB difference signals RDI, GDI, and BDI are sent to a defect detector (304). The defect detector (304) is RGB
The presence or absence of a defect is determined based on the threshold level of the difference signals RDI, GDI, and BDI, and if a defect is detected, a detection signal ERI is sent to the defect indicator (330).

The processing system for integral value comparison is an integrator (311), (31
2).

(313) and reference value setter (314), (315),
(316) and comparators (317) (318), (31
9) and a defective detector (320)
(100) to RGB inspection signals R8I, GSI, B
SI are integrators (311), (312), (
313), the image of one plate is integrated. The reference value setters (314), (315), and (316) are each set with RGB reference integral values.
It outputs GB reference value signals RR, GR, and BR. The reference value setters (314), (315), and (316) do not need to be off-the-shelf memory elements, and there will be no problem as long as they are voltage or current setters that can represent a constant magnitude or amount. .

RGB integral value signals RI, GI, BI and RGB output from integrators (311), (312), (313)
The reference value signals RR, GR, and BR are each provided by a comparator (317
), (318), (319) and the RG of both is compared.
B integral difference signal RD2. GD2. BD2 is sent to a defect detector (320). The defect detector (320) receives the RGB integral difference signal RD2. GD2.
From the BD2, for example, determine whether the cine is good or not based on the threshold level, and if there is a defect, the defect indicator (
The detection signal ER2 is sent to 330). Defective indicator (330
) notifies the occurrence of a defect based on the detection signal ERI or the detection signal ER2, and examples of this method include displaying an alarm or a lamp-lit display, marking the defective printed matter, and removing the defective printed matter.

The print inspection apparatus includes a timing controller (340) that controls the two processing systems and the two input devices. The timing controller (340) inputs pattern information according to the movement of a certain amount of printing paper based on the rotational pulse RP from the rotary encoder (30) which rotates in conjunction with the plunket cylinder of the printing press. Input device (100),
An input control signal IC is sent to the input device (200). Also, from the rotation pulse RP, the input device and end of the image information for one plate on the printing paper are detected, and a start signal ST is issued at the beginning, and an end signal EN is issued at the end. A processing system defect detector (304) based on mutual comparison of patterns detects defects only between the start signal ST and end signal EN.

Processing system integrator (311), (31
2), (313) are reset by the start signal ST and start integration immediately after that, and the fault detector (313) of the same processing system
320) detects a defect only when the end signal EN is received and the integration for the image on one plate is completed.

Since the present invention is as described above, it produces the following effects.

In other words, although the present invention has two input devices and two inspection processing systems, processing based on mutual comparison of patterns may cause sudden partial failures, while processing based on integral value comparison may cause overall failure due to accumulation of minute changes. By having each of them detect and share their roles, the structure of each processing system can be made extremely simple.

In addition, flexible inspection can be realized by performing inspection processing by mutual comparison of patterns without treating gradual density fluctuations within a range that does not cause abnormalities in the quality of printed matter as printing defects.

[Brief explanation of the drawing]

Figure 1 is an explanatory diagram of the printed matter inspection device installed on an offset rotary press, Figure 2 is an explanatory diagram of the input device of the printed matter inspection device inputting the design of the printed matter, and Figure 3 is the printed matter FIG. 4 is an explanatory diagram of the schematic configuration of the input device I of the inspection device, and FIG. 4 is a block diagram schematically showing the entire printed matter inspection device. (1)...Printing paper (2)...Printing unit (3)...Final printing unit (4)...Blanket cylinder (5)...Plate cylinder αQ...Rotary offset press (20 )...Illumination light (
3o)...ρ→me,・φ)f-4 encoder ゛-(1
00), (Punishment/input device (300)... Inspection device (101), (103), (104),
(105), (106)...Lens (111)
, (112), (113)... Dichroic mirror (121)... Array sensor (R) (122
)...Arayse/su (G) (123)...Array sensor (B) (130)...Aleise/su controller (3
01), (302), (303)... Comparator (
304), (320)...Failure detector (33
0)...Defective indicator (340)...Timing controller Patent applicant Toppan Printing Co., Ltd. Figure 1 Figure 3 100: 1:

Claims (1)

[Claims] (1) A device for inspecting printed matter on a printing press, which includes means for illuminating two sets of printed matter and inputting image information of the patterns on the printed matter, a means for converting the image information into electrical signals, and a means for inspecting repeated patterns on the printed matter. A mark comprising means for detecting a printing defect by comparing two pieces of corresponding image information, and means for detecting a printing defect by comparing a characteristic parameter of one image information with its reference value. Since the patterns are printed repeatedly, the comparison is made by simultaneously inputting two separate patterns from printed matter, comparing the corresponding two pattern information, and detecting the presence or absence of defective printed matter based on the presence or absence of a difference. A relative comparison that compares printable patterns and a simple absolute comparison that compares the characteristic parameters of the pattern information with a standard, which is characterized by the ability to inspect printed materials without installing a storage device for pattern information that serves as a standard. A printed matter inspection device is characterized by being able to detect printing defects in which the tone of a pattern changes gradually but significantly over time, which cannot be detected by relative comparison.