JPH03104640A - Color tone detector and printing quality inspector - Google Patents

Abstract

PURPOSE:To detect inferiority in color tone stably by a method wherein a total sum obtained with a total sum processing circuit is compared with a total sum stored in a reference memory according to each classification, and whether its difference is within a tolerable range or not is decided. CONSTITUTION:A reference memory 26 senses an image data of printed matter being a reference by the same condition as in inspection and according to each unit of a divided braid. Further, a differential processing circuit 24 calculates a difference between an output from the reference memory 26 and an output from a total sum processing circuit 22 for each area C1, C2,...Cn corresponding to each unit of the divided braid, and outputs it. Besides, a comparator 25 compares the output from the reference memory 26 with the output from the total sum processing circuit 22 for each area C1, C2,...Cn corresponding to each unit of the divided braid, judges whether its difference is within a tolerable value range and in case of without said range, outputs inferiority in color tone according to each unit of the divided braid.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a color tone detection device and a print quality inspection device that can reliably detect only color tone defects among printing defects.

Conventional technology> Conventionally, as a method for detecting defects in printed matter, image data of a reference printed matter is obtained in advance using an optical sensor, etc., and this image data is compared with actual 11 image data for each detection unit. There are some products that are determined to be defective if the difference is significant. Here, the defects include defects such as poor registration, poor color tone, and hissiness.

Of these, when it comes to detecting color tones, it may become impossible to detect the desired color tone, or there may be obvious differences in color tone, depending on items such as the sensitivity and dynamic range of detectors such as optical sensors, the illuminance of the subject, and the color of the printed material. However, since the detection output is small, a detection error may occur.

In other words, detection was unstable due to the limited performance of the detector itself.

Furthermore, even if a defect is determined by comparing image data, it is not possible to determine whether the defect represents poor registration, poor color tone, or lack of darkness such as hickeys.

Problems to be Solved by the Invention> Here, poor color tone generally does not occur locally, but rather does not occur globally or over a relatively wide area, although it depends on the printing method or the structure of the inking device. This is a phenomenon in which the density of a certain color increases or decreases over time. For example, in the inking device shown in FIG. 2, poor color tone actually occurs in units of blades, which are units in which the amount of ink supplied can be controlled.

That is, as shown in FIG.
Ink is supplied by the water supply device M3, and moisture is supplied by the water supply device M3, and the ink transferred from the plate cylinder 1 to the blanket cylinder 4 is
Printing is performed on paper held between a blanket cylinder 4 and an impression cylinder 5.

Here, as the inking device 2, a split blade 8 is attached to the bottom surface of an ink fountain 7 installed along a fountain roller 6.
It is constructed so that ink is supplied from the fountain roller 6 to the plate cylinder 1. A plurality of split blades 8 are arranged in a horizontal direction, and the gap between the split blades 8 and the top roller 6 is adjusted independently for each unit using a split blade actuator, thereby applying the paint onto the pot roller 6. The amount of ink applied is increased or decreased. The ink spread on the fountain roller 6 is passed to a transfer roller 9, kneaded by an ink roller row 10, and then transferred to the plate cylinder 1. In FIG. 2, reference numeral 12 is a printing quality control device, which adjusts the opening degree of the split blade 8 by a split blade actuator 11, and a pot roller rotation amount adjustment actuator]3 and a bottom roller rotating machine tank 14. It controls the rotation of the pot roller 6.

In this way, in the above printing method, the ink supply amount is controlled for each unit of the divided blade 8, so that poor color tone occurs for each unit of the divided blade 8. It was not possible to achieve stable detection by simply comparing each detection unit.

The present invention has been made in view of the above-mentioned prior art, and it is not possible to make only local comparisons of printed matter depending on the actual printing method.
The purpose of the present invention is to provide a color tone detection device and a print quality inspection device that can stably detect color tone defects by making detailed comparisons in which the ink supply amount can be controlled in units of units. .

Means for Solving the Problems〉 The configuration of the color tone detection device of the present invention which solves the above objects is that in a printing method in which the amount of ink supplied to the plate cylinder can be controlled independently in the width direction, the amount of ink supplied to the plate cylinder can be controlled directly or directly from the plate cylinder. An imaging device that indirectly captures an image in the width direction of printed matter; a synchronization device that operates the imaging device in synchronization with the vertical movement of the printed matter; an A/D converter for converting into a signal;
a grooving memory that classifies and sequentially stores image data digitized by the /D converter according to each control unit in the width direction of the ink supply amount; A summation processing circuit that performs summation for each classification; a reference memory that obtains and stores the summation of image data that has been classified in advance in accordance with each control unit in the width direction of the ink supply amount for a reference printed matter; and the summation processing circuit. The present invention is characterized in that a comparison circuit is provided which compares the summation calculated by /' with the summation stored in the reference memory for each category and determines whether the summation is within a permissible range.

Further, the configuration of the print quality inspection apparatus of the present invention that achieves the above object further includes the above A/D conversion!
an inspection memory that stores the entire image data digitized by the device; a reference memory that previously obtains and stores the entire image data of the reference printed matter; The present invention is characterized in that it includes a comparison circuit that compares the image data and determines whether the image data is within an allowable range.

Function> When the printed material moves in the vertical direction, it is synchronized by the synchronization device, the imaging device captures an image of the printed material in the horizontal direction, and the image signal is converted into a digital signal by the A/D converter. Then, the digitized image signals are classified according to each unit of the divided blades, stored in the grooving memory in series, and summed for each classification by the summation processing circuit. Thereafter, it is compared with the sum total of image data previously obtained and stored under the same conditions for a reference printed matter in the reference memory, and it is determined whether or not it is within the allowable range. Furthermore, print quality other than color tone detection will be inspected using the same process as in the past.

Embodiment Example C of the present invention will be described in detail below with reference to the drawings.

FIG. 1 shows a color tone inspection device according to an embodiment of the present invention. In the embodiment shown in the same figure, the configuration of the printing press is omitted, but as shown in FIG. #IEI independently in the width direction according to each unit
This applies to any printing method that can be used. That is, the impression cylinder 5
On the side of the CCD (ehar
A camera 15 is arranged, and an illumination device 16 is arranged above it.

The CCD camera 15 has a large number of semiconductor optical sensors arranged in a row so that it can take a horizontal image of the printed matter wrapped around the impression cylinder 5, and the output of each sensor with respect to the brightness of the image is calculated at the timing of generation FIll17. A/D
Output to converter 18.

The image signal sent to the A/D converter 18 is converted into a digital signal according to the clock A from the timing generation circuit 17 and sent to the pattern detection circuit 19. Pattern detection times ls
Reference numeral 19 sends only data within a preset range to the grooving memory 20. Extracting only data within a preset range in this way is difficult to do when looking at color tones because dirt and white spots are likely to occur in areas without patterns or at dusk, and at that time data fluctuates greatly. This is because it is inappropriate and that part will be deleted. Pattern detection time l1
The image data extracted by step 19 is sent to the grooving memory 20, where it is classified according to each unit of the divided blade and stored in series. Here, the image data obtained by one imaging is one-dimensional in the lateral direction of the printed matter. Therefore, in order to obtain planar, two-dimensional image data about printed matter, it is necessary to repeat imaging by the CCD camera 15 every time the printed matter is sent a certain distance in the direction of printing. Therefore, in this embodiment, the encoder 2 is mounted on the impression cylinder 5.
1, detect its rotation angle, and input it to the timing generation circuit 17. The timing generation circuit 17 has a function as a synchronization circuit, and outputs a clock B to the COD camera 15 every certain rotation of the impression cylinder 5, and the CCD camera 15 repeats imaging every time this clock B is input. become. Jutte, A/D conversion W18
, Pattern detection II! ! After step s19, the image data is sequentially stored in the grooving memory 20 according to the clock B, and the stored contents of the grooving memory are shown in FIG.
As shown in my mind, image data in the vertical and horizontal directions of printed matter is classified and stored into areas (addresses) C, , C, . Become. In Figure 3, the left and right direction is the COD camera 15.
The horizontal direction and the vertical direction of the printed material imaged by are the vertical direction of the printed material, which is the moving direction.

In the above embodiment, the CCD camera 15 is arranged on the side of the impression cylinder 5, and the encoder 21 detects the rotation angle of the impression cylinder 5, but it is possible to take images of printed matter at regular intervals. If so, the imaging position and detection method can be freely changed without being limited to this. In addition, as a printing method, if the ink supply rate can be adjusted for each divided blade, it is not limited to offset printing, which prints indirectly from the plate cylinder via the blanket cylinder, but it can also be a method of printing directly from the plate cylinder. It is also applicable.

Furthermore, the summation processing circuit IR522 includes the grouping memory 2
The image data is read from 0, and the total sum of image data and the number of detection units determined to be patterns are calculated for areas C, C2, ...C corresponding to each unit of the split blade, and then each area CI, The average value for the pattern portion is determined by dividing the total sum of image data for C, . The average value is sent to the difference processing circuit 24 and comparison circuit 25 when the changeover switch 23 is switched to inspection mode a, and is sent to the reference memory 26 when the changeover switch 23 is switched to reference memory mode b. The reference memory 26 captures image data of the reference printed matter under the same conditions as during inspection,
The same conditions are stored in correspondence with each unit of the divided blade, and are stored in advance prior to inspection. Further, the difference processing circuit 24 calculates the difference between the output from the reference memory 26 and the output from the summation processing circuit 22 for each area C,, C2, . . . C, corresponding to each unit of the divided blade, Output. On the other hand, the comparison circuit 25 compares the areas C, , C, . . . C. corresponding to each unit of the divided blade. ，
For each, the output from the reference memory 26 and the summation processing circuit 22
It is determined whether the difference is within the tolerance range, and if it is outside the range, a color tone defect is output for each unit of the split blade. The allowable value is sent from a CPU (central processing element) not shown, and the above-mentioned circuit etc. are controlled by this CPU.

If a color tone defect is output, the opening degree of each division blade is adjusted for each unit to control the ink supply amount and prevent the color tone defect from occurring.

In this embodiment having the above configuration, data processing is performed so that it is possible to compare each unit of divided blades instead of just comparing each COD detection unit. For this reason, the ink supply amount can be controlled, and it has become possible to compare each unit of the divided blade, which is a unit where poor color tone is likely to change. In other words, in the past, only a comparison was made for each COD detection unit, so it was not possible to identify whether there was a color tone defect, but in this embodiment, only a color tone defect can be reliably detected.

In the above embodiment, the comparison was made for each unit of the divided blades, but as a simple method, it is also possible to combine some of the units of the divided blades and perform the comparison. An overall comparison may be made without dividing.

Next, a print quality inspection device according to an embodiment of the present invention will be described with reference to FIG. 4. This embodiment has a configuration in which the above color tone inspection device is added to a conventional general print quality inspection device. That is, the A/D converter 18 (
The digitalized image data is then transferred to the selector switch 2.
When 7 is switched to inspection mode a, it is sent to the inspection memory 28, and conversely, when the selector switch 27 is switched to reference memory mode b, it is sent to the reference memory 29.

The inspection memory 28 stores the overall image data of the printed matter, and the reference memory 29 stores the image data of the reference printed matter captured under the same conditions as during inspection. It is something. Reference memory 29
, the image data stored in the inspection memory 28 are each sent to the sub-memory 30, a difference is determined for each detection unit of the CCD camera 15, and the difference is stored. The difference is then sent to the comparison circuit 31, which determines whether the difference is within the tolerance range from the CPU, and if it is outside the range, a print quality defect is output.

Incidentally, the comparison circuit 31 may share a part with the comparison circuit 25, and the same applies to the reference memory 29 and the test memory 28.

Furthermore, the above configuration may be provided for each color for colorization. The other configurations are the same as those of the embodiment described above, so the same parts are given the same reference numerals and the explanation will be omitted.

Effects of the Invention> As described above in detail based on the embodiments, the present invention enables not only local comparison but also control of ink supply amount for each controllable unit, depending on the actual printing method. By comparing the colors, it is now possible to detect color tone defects more reliably.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a color tone detection device according to an embodiment of the present invention, FIG. 2 is a block diagram showing an inking device for offset printing, and FIG. 3 is a block diagram showing the classification of image data stored in the grooving memory. FIG. 4, which is a conceptual explanatory diagram, is a configuration diagram of a print quality inspection apparatus according to an embodiment of the present invention. In the drawing, 1 is a plate cylinder, 2 is an inking device, 4 is a rubber cylinder, 5 is an impression cylinder, 8 is a split blade, 151 is a CCD camera, 16 is an illumination device, 17 is a timing generation circuit, and 181fA/D Converter, 19 is a pattern detection circuit, 20 is a grouping memory, 21 is an encoder, 22 is a summation processing circuit, 23 is a changeover switch, 24 is a difference processing circuit, 25 is a comparison circuit, 26 is a reference memory, 7 is a changeover switch) 8 is a test memory, 9 is a reference memory, 0 is a sub memory, and 1 is a comparison circuit.

Claims (2)

[Claims] (1) In a printing method in which the amount of ink supplied to a plate cylinder can be controlled independently in the width direction, an imaging device that captures an image in the width direction of a printed matter printed directly or indirectly from the plate cylinder; a synchronizing device that operates the imaging device in synchronization with vertical movement; an A/D converter that converts an image signal captured by the imaging device into a digital signal; a grooving memory that classifies and sequentially stores the image data according to each control unit in the width direction of the ink supply amount; and a summation processing circuit that sums up the image data sequentially stored in the grooving memory for each classification. and a reference memory that calculates and stores the sum of image data classified in advance according to each control unit in the width direction of the ink supply amount for the reference printed matter;
The color tone is characterized by being provided with a comparison circuit that compares the summation obtained by the summation processing circuit and the summation stored in the reference memory for each category and determines whether or not the summation is within an allowable range. Detection device. (2) In the color tone detection device according to claim 1, the A/
an inspection memory that stores the entire image data digitized by D conversion, and a reference memory that stores the entire image data of the printed material that is determined in advance as a reference;
A print quality inspection device comprising: a comparison circuit that compares the image data stored in the reference memory and the inspection memory to determine whether or not the image data is within an allowable range.