JPH07164619A - Printer control device - Google Patents

Abstract

PURPOSE:To achieve the water content control of an emulsified ink free from the deterioration of print quality due to each sectional condition of a printing step and environmental conditions. CONSTITUTION:When adjusting the content percentage of wetting water 5 to ink by the rotary speed of a water source roller 6 which is driven by a drive motor 17, a Hirakana letter (Japanese letter) image on the page of newspaper 22 rolling out of the press is photographed using a CCD camera 21, then the difference between the area of the Hirakana letter image part and the area of an image part having a reference image of Hirakana latter is interpreted using a computer image processing part 24. Further, this difference interpretation result is determined in terms of density difference, so that the density of a photographed image is adjusted to the density of the reference image by a wetting water control part 25 in a fuzzy control mode under the control of the motor speed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printing press controller for automatically adjusting the amount of dampening water relative to the amount of ink in a printing press.

[0002]

2. Description of the Related Art FIG. 3 shows a configuration of an offset printing machine including a rotary press and a conventional dampening water amount control example.

The ink of the ink fountain 1 is the ink source roller 2
It is called up by the ink roller group 3 along the surface, the ink film thickness is adjusted, and the ink is guided to the inking roller 4. The dampening water 5 is guided to the swimsuit roller 8 after the water film thickness is adjusted through the water source roller 6 and the roller 7.

The plate surface of the plate cylinder 9 is oleophilic in the image area and hydrophilic in the non-image area. By applying water and ink to the plate surface, an image of an emulsified ink mixed with dampening water is formed. Get to the department. This emulsified ink is used for the rubber blanket cylinder 10.
, And then to the printing paper 12 surface of the impression cylinder 11 surface. 13 is an intermediate body. In color printing, these units are provided in multiple stages for each color of ink.

Here, the emulsified state of the emulsified ink, that is, the balance between the amount of ink and the amount of dampening water, has a great influence on the print quality, and in particular is affected by the evaporation of water, making it sensitive to changes with time in the ambient environment such as temperature and humidity. react. Therefore, constant monitoring and skilled adjustment by the operator are required.

As a conventional automatic adjustment method for this balance, the publication "Measurement and Control, VOL31, No. 10, 1"
October 1992 issue, pp. 1041-1046, on-press measurement and printing-machine control, published by The Society of Instrument and Control Engineers.

In this conventional method, as shown in the figure, the infrared ray transmittance of the emulsified ink on the surface of the roller 14 is measured by a non-contact type ink film thickness / water content meter 15 utilizing infrared rays, and the emulsified ink is measured from this measured value. Of the water content is detected, the detected value is compared with the target water content by the control device 16, and the rotation speed of the drive motor 17 of the roller 7 is increased or decreased so that the difference between them is eliminated, that is, the rotation speed of the water source roller 6 is changed. Increase or decrease and adjust the amount of dampening water.

[0008]

In the conventional method, the print quality is improved by controlling the water content, but the desired water content on the surface of the roller 14 is obtained, but at the time of transfer on the plate cylinder 9. Ink film thickness and water content and wet state of printing paper 12,
The print quality changes depending on the condition of each part of the printing process such as temperature and humidity and the surrounding environment.

That is, in the conventional method, the water content on the surface of the roller 14 is controlled to the target water content, and this target water content is set according to an empirical rule. Since the water content control is not taken into consideration, it is difficult to improve the print quality.

Incidentally, in the conventional method, although the finished printing is inspected by a separate inspection device, this inspection is performed in terms of print quality (shading of printed matter, color tone change, stain by ink,
It does not have countermeasures / processing functions for quality improvement, but only for determining ink bleeding, white spots, etc.

It is an object of the present invention to provide a printing machine control apparatus which can control the water content of an emulsified ink without reducing the print quality due to the state of each part of the printing process and the surrounding environment.

[0012]

In order to solve the above-mentioned problems, the present invention provides a printing machine for obtaining an emulsified ink, which is a mixture of ink and dampening water, on the image portion of a plate cylinder and transferring it to printing paper. A photographing means for photographing a part of the image on the surface of the printed paper after printing, and a computer image processing unit for comparing the density of this photographed image with the density of a reference image which is the same as the photographed image. And a dampening water control means for controlling the amount of dampening water in a direction in which the density of the photographed image matches the density of the reference image based on the density comparison result.

Further, the computer image processing unit uses the character or graphic image as the reference image, and compares the image area of the character or graphic image with the image area of the same character or graphic in the photographed image. It is characterized in that the magnitude of the density is determined by using.

[0014]

Operation: The amount of dampening water is controlled by feedback control by comparing the density of the reference image that produces the same image as the printing density of the surface of the printed printing paper, and the printing density is adjusted to that of the reference image.

As a result, the control of the water content of the ink obtains the water content control including the state of each process and the change of the surrounding environment which affect the print quality, and the printing in which the deterioration of the print quality due to these factors is eliminated is obtained.

To compare the densities of the photographed image and the reference image, the size of the area of the character or graphic image is compared. As a result, the image density is made to correspond to "blurring" or "blurring" of characters or figures, and it is not necessary to detect the density itself in a captured image.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a block diagram of an apparatus showing an embodiment of the present invention. The dampening water 5, the dampening roller 6 and the drive roller 17 are the same as in the conventional case.

The CCD camera 21 takes the paper surface of the newspaper 22 printed by the printing machine as an object and shoots a certain position of the newspaper 22. This position identification uses a synchronization signal obtained from the cutoff controller 23.

The cut-off controller 23 extracts a signal when the newspaper 22 is cut after the final printing process as a synchronizing signal.

The computer image processing section 24 takes in the photographed image of the CCD camera 21, and judges the print density by comparing the densities of this photographed image and the learned photographed image previously photographed. As will be described later in detail, the determination of the print density is made by comparing the size of the image portion area of the hiragana characters at the same position on the paper surface.

The dampening water controller 25 controls the rotation speed of the drive motor 17 by fuzzy control based on the density discrimination signal from the computer image processor 24.

As described above, the amount of dampening water is controlled by performing feedback control based on the print density on the printed newspaper surface to adjust the print density to the set density. Therefore, the control of the water content of the ink is the water content control that includes the changes in the states of the process and the surrounding environment that affect the print quality, and it is possible to obtain printing in which the deterioration of the print quality due to these factors is eliminated.

FIG. 2 shows a flow chart of the print density discrimination and the dampening water control in the computer image processing unit 24 and the dampening water control unit 25.

The computer image processing unit 24 learns the character area of each of the 50 Japanese hiragana (S1).
In this learning, each hiragana on the surface of the newspaper 22 of good quality is photographed by the CCD camera 21, and this image is captured to obtain the area D of the black portion of the image portion.

Next, the computer image processing section 24 prints an image on the paper surface of the newspaper 22 which has been printed by the printing machine C
The image is taken in through the CD camera 21, and one arbitrary hiragana is picked up from this image (S2).

When the hiragana cannot be picked up (S3), the photographing position of the CCD camera 21, that is, the synchronizing position is changed (S4). As a result, a picked-up image of any one hiragana is picked up.

Next, the area S of the hiragana of one character picked up is calculated (S5), and this area S and step S1 are calculated.
The ratio A (= D / of the area D of the same hiragana to be learned in
S) is obtained (S6).

Next, the computer processing section 24 determines whether the area ratio A is within a certain range B (S7). The determination result is given to the dampening water control unit 25.

When the concentration ratio is within a constant range A = B, the dampening water control unit 25 continues the operation with the current dampening water amount without changing the rotation speed of the water fountain roller by fuzzy control ( S8).

When the ratio A is out of the range B,
It is determined whether or not A> B (S9), and when A> B, control for increasing the dampening water amount is performed (S10). Conversely, when A> B, control for reducing the dampening water amount is performed (S11).

The above steps S2 to S11 are performed by the CCD.
This is repeated for each one of the newspapers 22 transferred to the position of the camera 21 or for each appropriate number of newspapers.

As described above, it is necessary to determine whether or not the area of one hiragana is larger than the area of the same hiragana which is the reference, because "blurring" or "blurring" of the printed character changes the area of the character. From the area, it is determined whether the density is high or low by making the density correspond to the density of the character.

Therefore, the CCD camera 21 is only required to be able to discriminate between binary values of white and black as the density resolution of the image, and the CCD camera 21 and the computer image processing unit 2
It is possible to simplify the device configuration of No. 4 and the signal processing.

In the embodiment, the case where the control of the amount of dampening water is the fuzzy control is shown, but the same action and effect can be obtained by using the PI controller configuration of a general automatic control system.

The printing machine can be applied to a printing machine such as an offset printing machine which controls the amount of dampening water for ink.

Further, for the determination of the image density by the computer image processing unit, the area comparison of one hiragana is a preferable means in newspaper printing, but in the printed matter consisting of only alphanumeric characters and pictures, the density or density of the figure or character at an arbitrary position or It can be determined by learning the area in advance.

[0037]

As described above, according to the present invention, the amount of dampening water is controlled by feedback control by comparing the print density on the surface of the printing paper on which the printing is finished with the density of the reference image to obtain the same image, and the print density Since it was adjusted to the density of the reference image, the water content control of the ink is the water content control including the changes in the process conditions and surrounding environment that affect the print quality.
It is possible to obtain printing in which deterioration of print quality due to these factors is eliminated.

Further, according to the present invention, since the size of the area of the character or graphic image is compared in comparing the density of the photographed image and the reference image, the image density corresponds to "blurring" or "blurring" of the character or graphic. Therefore, it is not necessary to detect the density itself in the captured image, and the imaging device and the image processing device can be simplified.

[Brief description of drawings]

FIG. 1 is a device configuration diagram showing an embodiment of the present invention.

FIG. 2 is a flowchart of concentration determination and dampening water control in the embodiment.

FIG. 3 is a printing machine unit configuration and a conventional control example.

[Explanation of symbols]

 1 ... Ink fountain 5 ... Dampening water 6 ... Water source roller 9 ... Plate cylinder 12 ... Printing paper 15 ... Ink film thickness / water content meter 17 ... Drive motor 21 ... CCD camera 22 ... Printed newspaper 23 ... Cut-off controller 24 Computer image processing unit 25 Dampening water control unit

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display location B41F 33/14

Claims (2)

[Claims] 1. A printing machine for obtaining an emulsified ink obtained by mixing fountain solution with ink on an image portion of a plate cylinder and transferring it to a printing paper, and capturing a part of an image of the surface of the printing paper after printing. An image capturing unit, a computer image processing unit that compares the density of the captured image with the density of a reference image that is the same as the captured image, and the density of the captured image based on the comparison result of the density of the reference image. A printing press control device, comprising: dampening water control means for controlling the amount of dampening water in the direction of adjusting the concentration. 2. The computer image processing unit uses the character or graphic image as the reference image, and compares the image area of the character or graphic image with the image area of the same character or graphic in the captured image. The printing press control device according to claim 1, wherein the size of the density is determined based on the determination.