JPH02134249A - Hue control apparatus of planographic printing press - Google Patents

Abstract

PURPOSE:To enhance the control accuracy of a hue by measuring the dot area of the dot image of each color on newly printed matter and the mean density in a dot to compare the same with reference values and controlling the supply amount of ink and that of damping water so as to bring the obtained deviation values to zero. CONSTITUTION:In the hue control apparatus of a planographic printing press, the dot area A of the printed-off printing paper of a final color and the mean density D in a dot 24 are detected by a color television camera 2 equipped with a microscope unit 21. These detection signals are sent to a measuring control apparatus 3 and the obtained control signal is sent to the ink blade moving motors 5 - 8 of an ink supply apparatus and the water fountain roller rotating motors 18 - 21 of a damping water apparatus and the respective motors are controlled to control the supply amount of ink and that of damping water so as to keep a hue constant. At this time, the dot area A and the mean density D are compared with respective reference values to perform control so as to bring the deviation values obtained as the result of comparison to zero.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a color adjustment device for a lithographic printing press.

(Prior Art) The color adjustment device of a conventional lithographic printing press is explained with reference to Figs. 8, 9, and 10. In Fig. 8, (01) is the printing paper printed with the final color, and (02) is the same printing paper. (01) is a color sensor that detects the color of the printed surface; (03) is a control device.

In Figure 8.9.10, (04) is the ink blade of the ink supply device, (09) is the ink source roller, (011)
is ink, and the ink blade (04) is divided into a plurality of pieces in the width direction according to the pattern in the middle direction of the printed matter. In addition, (05) (06) (07) (08) are a plurality of ink blade movement motors provided in each of the above-mentioned ink blades (04), (012) is an ink roller group, and (013) is an ink depositing motor. Laura, (014
) is the plate surface of the plate cylinder, (015) is the water reservoir of the dampening water device,
(016) is the swimsuit roller, (017) is the swimsuit's low arm, and the color sensor (02) detects the color of the printed surface of the printing paper (01) printed with the final color.

The color separation signals (RGB signals, etc.) obtained by the same color sensor (02) are sent to the control bag W (3), where the same color separation signals are compared with the color measurement position of the printed matter that serves as a reference for proofs, etc. 3. If there is a difference between the two, calculate the ink supply amount for each color (four colors in the example in Figure 8) to make the deviation value zero at that time, and send the control signal obtained as a result to the control device (03). to the same ink blade moving motors (05) to (08), and the same ink blade moving motors (05) to (08)
) to move each ink blade (04) relative to the ink source roller (09), and move each ink blade (04) relative to the ink source roller (09).
4) and the same ink source roller (09) (010
) to adjust the amount of ink (011) stored between the ink blades (04) and the ink source roller (09) to be supplied to the ink roller group (012). (012), the ink is deposited on the plate surface of the plate cylinder (014) via a roller (013).
Transfer and supply to. In addition, in a lithographic printing press, the plate surface of the first plate cylinder (
It is not possible to form one image by simply supplying ink to (014), and it is necessary to supply dampening water that is repellent to oil-based ink to the portion of the plate surface (014) to which ink does not adhere. This dampening water is supplied by drawing out the dampening water stored in the water reservoir (015) as a water film by the rotation of the water source roller (16), and the dampening water passes through the roller (017) to the printing surface of the printing cylinder (
014).

(Problems to be Solved by the Invention) The conventional color adjustment device of a lithographic printing press shown in FIGS. 8, 9, and 10 has the following problems. In other words, the plate surface of the first plate cylinder (014
) A part of the dampening water supplied to the ink forming roller (013
) is emulsified in the ink and penetrates into the ink roller group (012), changing the ink transfer efficiency of the ink roller group (012) and transferring the ink to each ink blade (04).
Even if the gap (10) between the ink roller and the ink source roller (09) is constant, the film thickness of the ink transferred and supplied to one sheet of paper varies, resulting in a problem that the accuracy of controlling the two color tones is low.

The present invention has been proposed in view of the above-mentioned problems, and its object is to provide a color adjustment device for a lithographic printing press that can improve the control accuracy of one color tone.

(Means for Solving the Problems) In order to achieve the above object, the color adjustment device of the lithographic printing press of the present invention includes a color TV camera equipped with a microscope unit that detects halftone dot images of each color on the printed matter. Then, the image signal from the same color TV camera is processed and separated into halftone dot images of each color, and the halftone dot area and average density within the halftone dots of a certain color halftone image selected from among them are measured. The deviation value obtained as a result is sent as a control signal to the ink supply device and the dampening water device, and the amount of ink supplied from the ink supply device and the dampening water device is adjusted so that the deviation value becomes zero. and a measurement control device that adjusts the amount of dampening water supplied.

(Function) The color adjustment device of the lithographic printing press of the present invention is configured as described above, and the halftone dot image of each color on the printed matter is detected by a color TV camera equipped with a microscope unit. The image signal is sent to the measurement control device, where it is processed.

Separate into halftone dot images of each color, measure the halftone dot area and average density within the halftone dots of a certain color halftone image selected from among them,
The resulting deviation value is sent as a control signal to the ink supply device and the dampening water device, and the ink supply device and the dampening water device are controlled to make the deviation value zero. Adjust the ink supply amount and dampening water supply amount.

(Example) Next, the color adjustment device of the lithographic printing press of the present invention will be explained with reference to FIG.
) is a color TV camera, and (21) is a microscope unit attached to the same color TV camera (2).
) with a color TV camera (2). Also, (3) is the measurement control device.

(4) is the ink blade of the ink supply device, (9) is the ink source roller, and (11) is the ink. The ink blade (4) is divided into multiple pieces in the middle direction according to the pattern in the width direction of the printed material. has been done. Also (5) (6) (7)
(8) is a plurality of ink blade movement motors provided for each of the ink blades (4), (12) is an ink roller group, (13) is an ink deposition roller, (
14) is the plate surface of the printing cylinder, (15) is the water reservoir of the dampening water device, (16) is the water base roller, (17) is the swimsuit roller, and the water base roller (16) is the width direction of the printed matter. It is divided into multiple pieces in the width direction according to the picture. Also (18
) (19) (20) and (21) are the above water head rollers (
16) is a motor for rotating the water head roller.

Next, the operation of the color adjustment device of the lithographic printing press shown in FIG. 1 will be explained in detail. Printed paper with final color (1)
When the image is enlarged and observed, it is a collection of dots to which ink (11) has adhered, as shown in FIG. This point is called a halftone dot (24). The cross section of this halftone dot (24) is
Shown in the figure. The color tone of the printing paper (1) changes greatly depending on the halftone dot area A of the halftone dots (24) to which the ink (11) is attached and the average thickness (28) of the ink (11) within the halftone dots (24). As a result of various printing experiments, the following was found.

(2) The halftone dot area A of the halftone dot (24) changes depending on the amount of dampening water emulsified in the ink. An example of this is shown in FIG.

■Average thickness of ink (11) within halftone dot (24) (28)
teeth.

It changes depending on the amount of ink supplied. An example of this is shown in FIG.

However, this is because the average thickness (28) of the ink (11) within the halftone dot (24) is approximately proportional to the average density within the halftone dot (24). It can be considered that the density changes depending on the amount of ink supplied.

The color adjustment device of the lithographic printing press of the present invention uses a color TV camera equipped with a microscope unit (21) to measure the halftone dot area A and the average density within the halftone dots (24) of the printing paper (1) printed in the final color. (2), the detection signal obtained at that time is sent to the measurement control device (3), and the control signal obtained here is sent to the ink blade movement motors (5) to (8) of the ink supply device.
) and the motor (18) to (
21), and controls each motor to adjust the ink supply amount and dampening water supply amount so as to keep one color tone constant. That is, on the final printed printing paper (1), several color inks overlap or are adjacent to each other. Figure 2 shows the halftone dots of blue ink (25) and the halftone dots of red ink (25).
6) shows a mixed state. A portion (27) where the indigo ink dots (25) and the red ink dots (26) overlap is bluish-purple. The halftone dots of each color on the printed paper (1) are detected by a color TV camera (2) with an RJm mirror unit (21), and the image signal obtained at that time is sent to the measurement control device (3). Here, the same image signal is processed and separated into halftone dots of each color, and the halftone dots of a certain color selected from among the halftone dots are, for example, the halftone dots of indigo ink shown in FIG.
25) The halftone dot area A and the average density within the halftone dot (25) are measured and compared with the respective reference values, and the resulting deviation value is used as a control signal for moving the ink blade of the ink supply device. The ink blades are sent to the motors (5) to (8), and the ink blade movement motors (5) to (8) are driven to move each ink blade (4) relative to the ink source roller (9). Ink blade (4) and same ink source roller (9)
) and the ink (11) accumulated between each ink blade (4) and the ink source roller (9).
) to the ink roller group (12) to make the deviation value zero. In addition, the deviation value obtained by the control measurement device (3) is sent as a control signal to the water head roller rotation motors (18) to (21) of the dampening water device, and the rotation speed of each water head roller (16) is controlled. Change the above deviation value to zero.

Although this embodiment is an example applied to a single-fed printing press, it can also be applied to other lithographic printing presses such as a 9-wheel printing press.

(Effects of the Invention) The color adjustment device of the lithographic printing press of the present invention detects the halftone dot images of each color on the printed matter as described above with a color TV camera equipped with a microscope unit, and uses the image signals obtained at that time. Send to measurement control device.

Here, the same image signal is processed and separated into halftone dot images of each color, and the halftone dot area and average density within the halftone dots of a certain color halftone image selected from among the halftone dot images are measured, and each standard is determined. The deviation value obtained as a result is sent as a control signal to the ink supply device and the dampening water device, and the amount of ink supplied from the ink supply device and the dampening water device is adjusted so as to make the deviation value zero. Also, since the supply amount of dampening water is adjusted, the control accuracy for one color tone can be improved.

[Brief explanation of drawings]

FIG. 1 is a system diagram showing an embodiment of the color adjustment device for a lithographic printing press according to the present invention, FIG. 2 is an explanatory diagram showing halftone dots of each color of printed matter, and FIG. An explanatory diagram showing dots, Fig. 4 is an explanatory diagram of halftone dots, and Fig. 5 is a cross-sectional diagram of halftone dots.
Figure 6 is an explanatory diagram showing the relationship between the area of halftone dots and the water content in the ink, and Figure 7 is an explanatory diagram showing the relationship between the average density within the halftone dots and the gap between the ink blade and the ink source roller. , FIG. 8 is a system diagram showing a color adjusting device of a conventional lithographic printing press, FIG. 9 is a side view showing details of an ink supply amount adjusting section of the same color adjusting device, and FIG. 10 is a plan view thereof. (1)...Printed paper with final colors, (2)...
・Color TV camera, (21) ... Microscope unit (3) ... Measurement control device, (4) ... Ink blade of ink supply device, (5) (6) (7)
(8) ... Ink blade movement motor (9)
...Ink source roller. (11)... Ink, (12)... Ink roller group (13)... Ink deposits on roller, (14)
...Plate surface of the plate cylinder, (15) ...Water reservoir of the dampening water device, (16) ...Water base roller, (17) ・
... Swimsuit is Laura, (1B) (19) (20) (2
1) ... Mizumoto low rotation motor, (24) ... Halftone dots, (25) ... Indigo ink halftone dots, (26)
...Red ink halftone image. I Figure 6 Moisture content in ink (%) Figure 8

Claims (1)

[Claims] A color TV camera with a microscope unit that detects the halftone dot images of each color on the printed matter, and a color TV camera that processes the image signal from the color TV camera and separates it into halftone dot images of each color, from which a certain color is selected. The halftone dot area and the average density within the halftone dots of the halftone dot image are measured and compared with the respective reference values, and the resulting deviation value is sent as a control signal to the ink supply device and the dampening water device to calculate the deviation value. 1. A color adjustment device for a lithographic printing press, comprising: a measurement control device that adjusts the amount of ink supplied and the amount of dampening water supplied from the ink supply device and the dampening water device so as to make the color zero.