JPH04232055A - Printed matter checking device - Google Patents

Abstract

PURPOSE:To make high-speed checking possible by storing correction image data corrected by a change in the speed of printed matter in memory and ensur ing that an address in memory corresponds to image data before correction and printing speed. CONSTITUTION:Post-correction image data is previously calculated by correcting image data in accordance with printing speed, and this image data is stored at an address composed of a printing speed value and an image level value in a correction image data table. The correction image data is obtained by accessing the correction image table using image data from an image input camera and printing speed data from a speed detection part. An error detection part detects error using the correction image data.

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] That is, the printed matter inspection device of the present invention includes an image input device that inputs an image of a printed matter and outputs image data, and a device that detects the printing speed of printing paper and outputs the printing speed data. a speed detection section that corrects the image data according to the printing speed, calculates in advance corrected image data that corrects the image data according to the printing speed, stores this at an address consisting of a printing speed value and an image level value, and inputs the printing speed data and image data. a corrected image data table that generates an address and outputs the corrected image data; and a defect detection section that detects a defect occurring in a printed matter by detecting a difference between the corrected image data and reference image data stored in advance. It is characterized by

[0006]

[Function] The print inspection apparatus of the present invention has the following functions. The corrected image table stores in advance corrected image data that has been corrected according to the printing speed, and the address where the corrected image data is stored is the same as the corresponding printing speed value and image level. It has been set. Therefore, by accessing the corrected image data table using the printing speed data from the speed detection section and the image data of the image input camera as addresses, corrected image data corrected at the printing speed can be obtained. From this, the defect detection section can detect defects occurring in the printed matter by calculating the difference between the input corrected image data and the reference image data stored in advance.

[0007]

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.

[0008] In the figure, printing paper 4 for printed matter is transferred with a printing pattern by plate cylinder 1 when it passes between blanket cylinder 2 and 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. Although the present invention has been described as an example using an image input camera, the present invention is not limited to this, and a contact type sensor such as a photodiode array in which photodiodes are arranged in a line may be used.

The speed detection section is composed of a rotary encoder 7 attached to the blanket cylinder 2 to detect its rotational speed, and a speed converter 8 for determining the printing speed from the rotational speed detected by the rotary encoder 7. The rotary encoder 7 outputs a large number of pulse signals each time the blanket cylinder 2 rotates. The speed detector 8 counts the number of pulses and detects the printing speed of the rotating blanket cylinder 2.

In the corrected image data table 11, image data that has been corrected in accordance with the printing speed is stored in advance. Each piece of image data is stored in the corrected image data table 11 at an address consisting of printing speed and image data. This corrected image data 11
An example in which corrected image data is stored is shown in 1 below. In Table 1, the image data is 8-bit data (0-255), and the printing speed data is 6-bit data (0-64). For example, the maximum printing speed is 63 m/min,
If the current printing speed is 1 m/min and the image input camera has 255 image data, the corrected image data is 7. If the input camera has 255 image data, the corrected image data is 7.

[0012] As this corrected image data table, for example, PROM or SRAM is used.

The defect detection section 12 compares the corrected image data with the normal image data into which the normal pattern of the printed matter has been input in advance, and determines that there is a defect if there is a difference. The defect detection section 12 outputs a defect detection signal and sends it to an output device such as a display or a printer to display the defect result.

[0014]

[Table 1]

The processing section 13 also stores the corrected image data in the corrected image table 11 via the bus 14. The A/D converter 10 performs analog/digital conversion of the image signal input by the image input camera 5 and the printing speed signal detected by the speed detector.

Next, an inspection method using the printed matter inspection apparatus of the present invention will be explained with reference to FIG. Image data is continuously inputted to the image input camera 5, and the printing speed at the time when the image data is inputted by the image inputting camera 5 is detected by the speed detecting section, and this printing speed data is output. The corrected image data table is accessed using an address consisting of this image data and printing speed data, and the accessed data becomes corrected image data and is output to the defect detection section 12. The defect detection unit 12 detects defects based on the corrected image data.

[0017]

According to the present invention, corrected image data is stored in advance in an image correction table, and the address where this corrected image data is stored is the same as the level of the original image data before correction and the input of the original image data. It is configured based on the printing speed when Therefore, by inputting image data and printing speed data and accessing the corrected image data using this address, you can obtain corrected image data with the printing speed corrected, eliminating the need to calculate correction values. Therefore, the inspection speed can be increased.

[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 Correction image data table 12
Defect detection section 13 Processing section 14 Bus

Claims (1)

[Claims] Claim 1: A printed matter inspection device for inspecting a printed pattern consisting of characters, symbols, or pictures continuously printed on printed paper, comprising: an image input device for inputting an image of a printed matter and outputting image data; A speed detection section that detects the printing speed of the printer and outputs the printing speed data, and an address that calculates in advance corrected image data that corrects the image data according to the printing speed and configures this with a printing speed value and an image level value. A corrected image data table that inputs the printing speed data and image data, generates an address, and outputs the corrected image data, and calculates the difference between the corrected image data and pre-stored reference image data and prints it on printed matter. A printed matter inspection device comprising: a defect detection section that detects defects that have occurred.