JP2004090644A - Quality control apparatus for printed matter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a quality control apparatus for controlling the quality of printed matter, in particular printed paper sheets, including a device for recording image data of the printed matter carried through a printer and an analyzer provided subsequently to the recording device, wherein the analyzer is provided by further improving a device for processing the image data in relation with data stored in a memory device connected with the analyzer to simply and automatically preset a region to be inspected in an object to be printed. <P>SOLUTION: The printed matter 2 reproducing regions 12; 12.1; 12.2; and 12.3 to be inspected can be scanned by the recording device 5. Data for characterizing the regions 12; 12.1; 12.2; and 12.3 can be detected in the analyzer 7 by the scanning and stored in the memory device 8. Further the data can be used for analyzing the image data of the printed matter 2. <P>COPYRIGHT: (C)2004,JPO

Description

The present invention relates to an apparatus for quality control of printed matter described in the writing section in the preamble of claim 1.

In sheet-fed web offset printing presses, the values obtained for the printed product by measurement are examined and this actual value is used to adjust the printing device against (in relation to) a preset ideal value. It is known. In a so-called in-line inspection system, preferably, for this purpose, a camera is provided downstream of the last printing device, so that the sheet is moved while the sheet is moving. Is to be taken. The image data thus detected can then be compared on a pixel-by-pixel basis with a preset ideal value for brightness and / or its color. In addition, such a system can detect dirt, contamination, or scratches (eg, due to oil splashing) on the printing surface.

An image inspection system for use in a printing device of the kind briefly outlined above is known, for example, from EP 0 378 283 A1. Using a camera, the sheets on the counter impression cylinder of the last printing device are scanned line by line. By means of the appropriate illuminating means, a linear illumination suitable for scanning the scanning line camera line by line is provided. This camera is followed by an image analysis device, which makes it possible to compare the image data obtained by the camera with an ideal value preset for each pixel.

イ ン ラ イ ン similarly, from DE-A 19 604 241 as patent document 2, an in-line image inspection system for a printing device is likewise known. In this device, the sheets moved on the cylinder are scanned line by line.

The advantage of such an in-line sheet inspection system is that each printed sheet can be detected and analyzed by measurement. At this time, analysis can be performed from the obtained measurement values based on various viewpoints.

However, a disadvantage of such a system is that the analysis is performed without the entire image area to be detected being set in advance. This means that not only the printed cutout (Nutzen), but also the parts of the sheet which are not printed and which are later cut off by punching or cutting are analyzed. In some cases, defects or ink deposits (e.g., smudges) present in this insignificant printing sheet area are recognized as faulty by an automation device of appropriate nature and, for example, removed. It may happen that the setting on the device side is changed or the device is shut down.

In order to avoid this problem, the image area to be inspected is separated from the area where the inspection may not be performed, that is, a suitable area is determined by data that can be manually input before performing the image inspection. It is known to make a mark to distinguish them. Data can be manually input by using a mouse or a joystick on one of the monitors provided in the image inspection system. The boundary, which is input in advance in this way and separates the image data of the inspection target from the image data of the non-inspection target, is then stored in the storage device of the inspection system, and is used when analyzing and evaluating individual image data. .

The problem at this time is that the adjustment of the image area to be inspected may be quite troublesome and time-consuming depending on the preset observation object. This is especially true in the case of multiple cutouts. For this reason, it is not possible to exclude a situation in which the worker forgets a certain area or erroneously draws a boundary when classifying the observation target to be inspected.
European Patent No. 0378283 German Patent Invention No. 19604241

Accordingly, the object of the present invention is to further improve the apparatus for quality control of printed matter described in the writing section in the preamble of claim 1 so that the area to be inspected in the printing object can be simply and automatically determined. Is to be set in advance.

課題 This object is achieved by a configuration according to the present invention. Further embodiments of the invention are given from the subclaims.

According to the present invention, data for separating the image area to be inspected from the remaining image areas can be detected using the image data itself obtained by the image capturing apparatus (camera). To do so, reference is made here to a single printed sheet, and a standard setting of the appropriate threshold values for lightness (Helligkeit) and / or hue (Farbton) and / or saturation (Saettigung). Thereby, the image area to be inspected can be automatically detected, and the image area can be appropriately stored in the storage device as such. The boundary between the image area of the inspection target and the image area of the non-inspection target is thus detected from the image data itself by the analysis device provided after the camera.

According to a preferred embodiment of the present invention, a special sample sheet generated from the pre-stage data is created for inputting the inspection area. The sample sheet has a surface to be inspected as a region colored in a predetermined color (for example, gray) corresponding to the cutout portion to be observed. Such a learning sheet, or in other words a sample sheet, can be produced, for example, by a plotter or a calibrator. At this time, the original observation target (cutout portion) can be formed on a uniformly colored surface. The sample sheet thus generated is then passed through a printing press in an expected operation (Tippbetrieb) and detected by an imaging device provided in the last printing device. Then, in the analyzer, the image areas to be inspected which are colored in a special color are distinguished from the image areas which are not inspected by setting appropriate threshold values for brightness and / or hue and / or saturation.

According to a further embodiment of the present invention, reference values relating to how to analyze or weight various image areas using sample sheets detectable with the image capturing device are also input to the analyzing device. Is done. For this purpose, different colors and / or different brightness colorings on the sample sheet are used so that the image areas to be analyzed and evaluated with a certain weighting factor or sensitivity are separated from one another. A leaf can be made. In this case too, a correspondingly produced sample sheet is passed through the printing press, for example, in the anticipated operation, and is photographed by a camera mounted on the last printing device. The appropriate surface area is then recognized in the analyzer by means of a threshold factor for brightness and / or hue and / or intensity, and the data thus obtained are stored for later image examination.

The stored data reproducing the image area to be inspected is then used to further evaluate the sheets printed during the printing operation. Only in an image area provided in advance for image inspection, analysis is performed by comparing the image data with an ideal reference value, and a defect is detected. False coloring, image errors, or hindrances that can occur outside of this area are not considered. Therefore, it is possible to avoid the stoppage of the printing press and other erroneous judgments regarding the quality of the manufactured product.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 shows a counter impression cylinder of a printing device of a sheet-fed web offset printing press, not shown in detail. Above the counter impression cylinder 1 there is a sheet 2 held by grippers, which sheet 2 is guided through a printing gap between the impression cylinder 1 and the blanket cylinder 3. . As is well known, a plate cylinder 4 cooperates with the rubber blanket cylinder 3. In the figure, the rotation direction of the opposing impression cylinder 1 is indicated by an arrow.

カ メ ラ A camera 5 is provided on the opposing impression cylinder 1 in a spaced state. The camera 5 detects a print image printed on the sheet 2. The camera 5 is preferably a scanning camera (Zeilenkamera) capable of capturing a printed image in RGB channels in color. An illumination device 6, preferably formed as a fluorescent tube, is provided to evenly adjust each printed image captured in the scanning line.

解析 The camera 5 is followed by an analysis device 7 configured as a computer. The analysis device 7 is connected to the storage device 8, the input device 9, and the monitor 10. Further, the analysis device 7 is connected so as to be able to exchange signals with an angle sensor (Winkelgeber) not shown here, whereby the reading of the image sequence detected by the camera 5 is performed by the rotation of the opposing impression cylinder 1. It can be synchronized with the movement of.

FIG. 2 a shows a first embodiment of the present invention. In the figure, a sample sheet 11 is shown, on which a cutout 12 to be printed in a predetermined color is marked. At this time, it is preferable that the sample sheet 11 is made by an appropriate color printer before printing. Here, the sample sheet 11 has the same plate type as the sheet to be printed later by the corresponding printing device.

The sample sheet 11 having the observation object indicated by the cutout 12 is passed through a printing device before printing is started. At this time, an image on the sample sheet 11 is detected by the camera 5. The analysis device 7 distinguishes, that is, separates the analysis target region outside the cutout unit 12 from the image region of the cutout unit 12 using a threshold value input in advance. The image area to be analyzed is stored in the storage device 8 accordingly. At this time, the data automatically read as described above can be additionally manually processed through the input device 9 connected to the monitor 10 and further corrected if necessary.

(4) When the cutout 12 on the sample sheet 11 is detected, and the analysis device 7 is prepared in the storage device 8, the printing target sheet can be printed by the printing press. This sheet is detected by the camera and analyzed by the analyzing device 7. At this time, pixels are compared only in the region of the cutout portion 12 to be analyzed.

FIG. 2b shows yet another configuration of the sample sheet 11; In this case, the cutouts provided for image inspection are represented in the form of cutouts 12.1, 12.2, 12.3 for three different evaluation targets. This can be represented by different brightnesses, shades, or even shapes and configurations. By presetting the appropriate threshold criteria for brightness, color and / or configuration, the identification of the cutouts 12.1, 12.2, 12.3 to be evaluated differently is made possible by the analyzing device 7. At this time, when analyzing the sheet to be printed later, the cut-out portions 12.1, 12.2, and 12.3 represented differently are used to detect and analyze a defective portion in the image. To this end, different sensitivities and / or weightings can be assigned. In this way, the very important image cutout 12.1 can be made more sensitive, while the less important part 12.2 is assigned a lower sensitivity. Here too, a sample sheet 11 with cutouts 12.1, 12.2, 12.3 is photographed with the camera 5 in a so-called recognition run, and analyzed by the analysis unit 7. . The corresponding parts are stored in the storage device 8 and are ready for further sheet inspection by the analysis unit 7.

FIG. 3 is a diagram showing components of an image inspection according to the present invention. FIG. 4 shows a sample sheet according to the invention. FIG. 4 shows a sample sheet according to the invention.

Explanation of reference numerals

DESCRIPTION OF SYMBOLS 1 ... Counter pressure cylinder 2 ... Sheet paper 3 ... Rubber blanket cylinder 4 ... Plate cylinder 5 ... Camera (photographing device)
6 Illumination device 7 Analysis device 8 Storage device 9 Input device 10 Monitor 11 Sample sheet (test sheet)
12 ... cutout part 12.1, 12.2, 12.3 ... cutout part

Claims (5)

A device for quality control on printed matter, especially printed sheets, wherein the device for photographing image data of the printed matter moved through a printing press, and an analysis device provided after the photographing device. Wherein the analyzer is provided to process the image data in association with data stored in a storage device connected to the analyzer,
The imaging device (5) is provided so as to scan a printed matter (2) that reproduces the inspection target area (12; 12.1; 12.2; 12.3). 12; 12.1; 12.2; 12.3) are detectable from the scan in the analysis device (7) and are storable in the storage device (8); An apparatus characterized in that the apparatus can be used when analyzing image data of a printed matter (2). The apparatus according to claim 1,
An apparatus, characterized in that the printed matter (2) that reproduces the area to be inspected (12; 12.1; 12.2; 12.3) is formed as a test sheet (11). The apparatus according to claim 2,
The test sheet (11) is formed as a sheet that reproduces the object to be printed. At this time, in order to detect the area (12; 12.1; 12.2; 12.3) to be inspected, A device provided so that a threshold value relating to brightness and / or intensity and / or hue can be preset in the analysis device (7). The device according to claim 3,
The apparatus according to claim 1, characterized in that the test sheet (11) comprises the area to be inspected (12; 12.1; 12.2; 12.3) in the form of a uniformly colored surface. . The device according to claim 3,
The test sheet (11) is characterized in that it comprises the area to be tested (12; 12.1; 12.2; 12.3) in the form of a differently colored surface. apparatus.

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