JPH04232056A - Printed matter checking device - Google Patents

Abstract

PURPOSE:To correct printing speed and the luminous quantity of a light source based on the image data of a print pattern in which an image is entered by storing image data in a routine white paper part previously, then entering the image data of the white paper part present between print patterns and, determining the ratio of the mentioned two different sets of image data to obtain correction factor. CONSTITUTION:The subject device is composed of the first memory device which stores image data on a normal white paper part entered previously, using a camera for image entry, a white paper detection part which detects the white paper part between the printed patterns of a printing sheet and permits an image to be entered using the camera for image entry, a correction factor calculation part which calculates a correction factor based on the ratio of image data in the white paper part between the mentioned patterns and image data in the first memory device, the second memory device which stores the calculated correction factor, and a correction part which corrects image data on the print pattern entered using the camera for image entry based on the correction factor in the second memory device.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printed matter inspection apparatus for in-line inspecting a printed pattern printed on printed paper.

0002

2. Description of the Related Art Conventionally, there has been an apparatus for inspecting printed paper for printed matter, such as that described in Japanese Patent Application Laid-Open No. 62-219648. As shown in FIG. 2, in this device, when the printing paper 4 passes between the blanket cylinder 2 and the impression cylinder 3,
The printed pattern is transferred onto the printing paper 4. The image input camera 5 scans the printed pattern of the printing paper 4 that has passed between the blanket cylinder 2 and the impression cylinder 3 in the width direction, and continuously detects the shading of the printed pattern in the same width direction. It has become. Here, when the printing speed of the printing press changes, the exposure time of the image input camera 5 changes, and the density signal obtained by scanning the printed matter changes. A typical printed matter inspection device inspects for defects by taking the difference between a standard grayscale signal and a grayscale signal of a printed matter to be inspected. At this time, if the exposure time of the image input camera 5 changes, the density level of the printed material to be inspected changes, resulting in an erroneous determination. For this purpose, a rotary encoder 7 is attached to the blanket cylinder 2 to detect the number of rotations, and a speed converter 8 is connected to the rotary encoder 7 to determine the printing speed from the detected number of rotations. is being sensed. Other correction methods include the one described in Japanese Patent Application Laid-Open No. 1485852/1983, which uses a divider that divides a pre-stored printing speed by the printing speed at the time of inspection, and a The result is multiplied by the print density signal at the time of inspection. From this, the amplifier 9 corrects the image data including the printed pattern from the image input camera 5 so as to be proportional to the speed signal from the speed converter 8, and sets the gray level of the image data to be constant. Finally, the signal processing circuit 6 compares the obtained image data with normal gradation data previously stored in the signal processing circuit 6, and detects defects in the printed material from the difference.

0003

However, according to the print inspection device that changes the amplification factor of the amplifier connected to the image input camera described above, it is possible to accurately correct the wide printing speed range detected by the speed detection device. It's difficult to do. Furthermore, with the method of using dividers and multipliers, it was difficult to achieve high-speed division and multiplication in response to increasing printing speeds.

[0004] The present invention is capable of deriving correction values for image data at high speed over a wide speed range.
The purpose of the present invention is to provide an apparatus that improves the inspection speed of printed matter inspection.

[0005]

[Means for Solving the Problems] The print inspection device of the present invention inputs a print pattern continuously printed on printing paper as an image using an image input device, and combines this image data with image data of a normal print pattern input in advance. In other words, the image input camera is used to input a normal blank part of the paper in advance, and the area between the first memory that stores this image data and the printed pattern of the printed paper is used to inspect the printed matter for defects. a blank page detection unit that detects a blank page portion and inputs the image with an image input camera; and a correction that calculates a correction coefficient based on the ratio of image data in the blank page portion between the patterns and image data in the first memory. a coefficient calculation unit; a second memory that stores the calculated correction coefficient;
It is characterized by comprising a correction section that corrects the image data of the print pattern input by the image input device using the correction coefficients in the second memory.

[0006]

[Function] The print inspection apparatus of the present invention has the following functions.

[0007] First, the first memory stores image data of a normal blank paper pattern that has been input as an image in advance. The blank area detection section detects the blank area between the printing patterns on the printing paper and inputs the image. Naturally, the image data of this white area is multiplied by the effects of the current printing speed and the light intensity of the light source. It is what I received. The correction coefficient calculation unit calculates a correction coefficient by calculating the ratio between the image data of the blank area between the print patterns and the normal blank image data in the first memory, and temporarily stores this in the second memory. let The correction unit corrects the input image data of the print pattern using the correction coefficients stored in the second memory, but as described above, this corrected image data has correction coefficients that are based on the printing speed and the light intensity of the light source. The influence of can be removed.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a block diagram showing an embodiment of a printed matter inspection apparatus according to the present invention. Note that in the figure, the same reference numerals represent the same members.

In the figure, a print pattern is transferred to a printing paper 4 of a printed matter by a plate cylinder 1 when it passes between a blanket cylinder 2 and an impression cylinder 3.

The image input camera 5 includes a rubber cylinder 2 and an impression cylinder 3.
The printed pattern of the printing paper 4 that has passed between the two is scanned in the width direction, and the shading of the printed pattern in the same width direction is continuously detected. The image signal from the image input camera 5 is converted into a digital signal by the A/D converter 10. In this example, a camera is used as the image input device, but the present invention is not limited to this, and a contact type sensor using a photodiode array or the like may be used, for example.

The selector 11 transmits data to the first memory 12, the correction coefficient calculation section 13, or the correction section 15 using image data from the image input camera. That is, in the selection, if it is normal blank image data that has been input as an image in advance, it is sent to the first memory 12. Further, if the image data is detected to be that of a blank page between print patterns, it is transmitted to the correction coefficient calculation section 13. If it is image data of a print pattern, it is sent to the correction section 15. The selection 11 shown in this embodiment shows an example in which it is detected whether it is a blank area between print patterns or image data of a print pattern. Note that the first memory 12 stores the normal image data of the blank section sent from the selector 11.

Next, the correction coefficient calculation unit 13 is a memory table that stores correction coefficients calculated by taking the ratio between normal blank image data and blank area image data between printing patterns. Each correction coefficient is stored at a predetermined address in this table, and this address corresponds to the blank area between the normal blank image data stored in the first memory 12 and the print pattern sent from the selector 11. It is composed of image data. Therefore, when the image data in the first memory and the image data sent from the selector 11 are input to the correction coefficient calculation unit 13, a correction coefficient corresponding to the image data is outputted.

Next, the second memory 14 stores the above-mentioned correction coefficients.

[0014]The correction unit 15 includes a correction coefficient calculation unit 1
3, this is a memory table in which image data corrected using this correction coefficient is stored. Therefore, the corrected image data is stored in the correction unit 15 at the address of the correction coefficient stored in the second memory and the print pattern data sent from the selector 11. therefore,
When the correction coefficient and the image data of the print pattern are input, the correction unit 15 outputs corrected image data.

The defect detection section 16 detects defects by comparing the corrected image data with image data of a normal printing pattern inputted in advance. Then, a detection signal from which a defect is detected is sent to a device that outputs the inspection results, such as a display or a printer.

The processing section 17 controls each section via the bus 18.

[0017]

According to the present invention, the image data of the print pattern is corrected using a correction coefficient obtained by taking the ratio of the image data of the normal blank part and the image data of the blank part between the print patterns. The printing speed of the printer and the light intensity of the light source can be corrected at once.

Furthermore, since the correction coefficient and the image data corrected using the correction coefficient are stored in the memory table, correction processing can be performed at high speed.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram for explaining an embodiment of a printed matter inspection apparatus of the present invention.

FIG. 2 is a configuration diagram showing a conventional print inspection device.

[Explanation of symbols]

1 Plate cylinder 2 Blanket cylinder 3 Impression cylinder 4 Printing paper 5 Image input camera 6 Signal processing circuit 7 Rotary encoder 8
Speed detector 9 Amplifier 10 A/D converter 11 Selector 12 First memory 13 Correction coefficient calculation section 14 Second memory 15 Correction section 16 Defect detection section 17 Processing section 18 Bus

Claims (1)

[Claims] Claim 1: A printed matter in which defects in the printed material are inspected by inputting a printing pattern continuously printed on printed paper using an image input device and comparing this image data with image data of a normal printing pattern inputted in advance. In the inspection inspection apparatus, a first memory for inputting a normal blank part in advance with the image input device and storing this image data;
a blank paper detection section that detects a blank section between printing patterns on printing paper and causes an image input device to input an image; a correction coefficient calculation unit that calculates a correction coefficient based on a ratio; a second memory that stores the calculated correction coefficient; and image data of a print pattern input by an image input device using the correction coefficient in the second memory. 1. A printed matter inspection device comprising: a correction section for correcting.