JPH04103351A - Color tone controller - Google Patents

Abstract

PURPOSE:To make a color tone in a proper value by performing a comparison operation of densities of a solid part, a halftone dot part and a desired value, and controlling supplying quantities of an ion supply device and a damping water supply device by a controller. CONSTITUTION:A density of a proper solid part 2 of a printing matter 1 and a desired density of a halftone dot part 6 are inputted in a controller 4. The density of the solid part 2 and the density of the halftone dot part 6 measured by a line type image camera 7 are compared with a desired density 31 fetched from an image memory 12 so as to obtain a deviation value. The controller 4 sends signals to an ink supply device 5 and a damping water supply device 14 until the deviation value becomes zero. Thus, the ink supply quantity and damping water supply quantity are kept properly.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an automatic control device applied to color tone control of a lithographic offset printing press.

[Conventional technology]

As shown in the apparatus schematic layout diagram in FIG. 6 and the control block diagram in FIG. The control device (computer) 4 gives a signal to the ink supply device (ink key opening control device) 5 to control the ink supply amount so that the deviation from the ink supply amount becomes O.

[Problems to be Solved by the Invention] 1) As shown in FIG. 2 (a> to fd), the color tone of the printed matter 1 is determined by changes in the density of the solid area 2 of the printed matter 1 and the halftone dot area 6.
However, controlling the ink supply amount alone cannot bring the densities of both to an appropriate value at the same time. This is because both 'ζ will change due to changes in the amount of dampening water supplied into the ink due to environmental changes.

2) As shown in Figure 2 fd1, is it possible to control the color tone (contrast) optimally by controlling the ink supply amount alone? 1 cannot be done.

(Means for Solving the Problem) By keeping the density of the solid area and the density of the halftone area to the target, the density of the evening area and the density of the halftone area, respectively, the color tone is always maintained at an appropriate level. For this reason, the following specific measures will be taken.

1) A sensor is provided to detect the density of the solid portion and the density of the halftone portion of the printed matter.

2) Through basic experiments, understand the density change characteristics of solid areas and halftone areas with respect to changes in ink and dampening water supply as shown in Figure 2 fat to fdl, and based on that data, A multiple regression analysis formula for determining changes in the amount of ink and dampening water supplied with respect to changes in the density of the halftone dot area is determined in advance.

3) Compare the target density of the solid area and the density of the halftone area with the current density of the dark area and the density of the halftone area, calculate the deviation value using the multiple regression equation obtained in the above 2), A control device is provided that outputs a signal to appropriately control the ink supply amount and dampening water supply amount.

(Function) In advance, the density of the target solid area and the density of the target point area where the gradation is to be maximized are input into the control device, and the current density of the solid area and the density of the halftone area sent from the sensor are input into the control device. A comparison calculation is made with the target value, and a signal is sent from the control device to the ink supply device and the dampening water supply device to change the respective supply amounts, thereby controlling the color tone to always be at an appropriate value.

〔Example〕

Embodiments of the present invention will be described with reference to FIGS. 1 to 5. FIG.

In the figure, 1 is a printed matter, 2 is a solid area, 3 is a target solid area density, 4 is a control device (computer), 5 is an ink supply device (ink key opening control device), 6 is a halftone dot area 7 is a line type image camera, 8 is the key width, 9 is the grip, 10 is the bottom, 11 is the batch, 12 is the image memory, 13 is the target halftone density, 14 is the dampening water supply device f (water base roller opening amount control device ).

As shown in Fig. 3, the density of the hem portion 2 in the vertical and width directions and the halftone dot portion 6 (area where colors are not mixed, i.e., the color you want to control) for each key width 8 of the printed matter The key width 8 where the solid area 2 and the halftone dot area 6 are not present is input to the control device 4 to input the target density of the halftone area 6) where only the halftone area 6) is present. Patch 11 of portion 6 is provided in advance).

2) As shown in FIG. 4, the line-type image camera 7 measures the density in the width direction of the printed matter 1 during operation in the vertical direction and stores it in the image memory 12 in the control device 4.

3) Call up the density of the solid part 2 and the density of the halftone part 6 at the position specified in the above 1) for every 8th key from the image memo January 2, and set the target solid part density 3 and the target halftone part density 13. Compare with.

4) The deviation value obtained in the above 3) is used in a multiple regression equation to estimate the change in ink and dampening water supply amount from the density change of the solid area 2 and the halftone area 6, which are preset in the control device 4. By substituting it, proper signals are given to the ink supply device 5 and the dampening water supply device 14.

5) The ink supply device 5 and dampening water supply device 14 include:
A signal is sent from the control device until the deviation value becomes O,
Always keep the ink supply amount and dampening water supply amount appropriate.

The above color tone control process is shown in a block diagram as shown in FIG.

〔Effect of the invention〕

A color tone control device according to the present invention includes a means for detecting the density of a solid part and a halftone part of a printed matter, and a target density of a solid part and a halftone part inputted in advance and a solid part of a printed matter obtained by the detection means. By providing means for comparing and calculating the density of the area and the halftone area, and means for controlling the ink supply amount and the dampening water supply amount based on the result of the comparison calculation, the following effects are achieved.

1) The color tone and gradation of printed matter are affected by changes in the density of solid areas and halftone areas of printed matter, but in the present invention, both the ink supply amount and dampening water supply amount are controlled at the same time. The concentration of can be set to an appropriate value at the same time.

[Brief explanation of drawings]

FIG. 1 is a schematic layout diagram of a color tone control device according to an embodiment of the present invention, and FIG. 2 ta+ to fdl are based on experimental data regarding changes in solid area density and dot area density based on changes in ink and dampening water supply amounts. The obtained graphs, FIG. 3, are diagrams showing the appropriate dimming area reduction and halftone area density to be input to the control device, and FIG. 4 is a graph showing the stamp I! A diagram showing a mechanism for outputting paper density during operation to an image memory in a control device using a line-type image camera, FIG. 5 is a color tone control Pronk diagram according to the present invention, and FIG. 6 is a diagram showing a conventional color tone control device. A schematic layout diagram showing
FIG. 7 is a conventional color tone control block diagram. 1... Printed matter 2... Solid portion 3...
Target solid area density 4... Control device 5... Ink supply device 6... Halftone area 7... Line type image camera 13... Target halftone area density 14... Dampening water supply device

Claims (1)

[Claims] means for detecting the densities of solid parts and halftone dot parts of a printed matter; target densities of solid parts and halftone dot parts inputted in advance; and densities of solid parts and halftone dot parts of the printed matter obtained by the detection means; 1. A color tone control device comprising: means for performing a comparison calculation; and means for controlling an ink supply amount and a dampening water supply amount based on the results of the comparison calculation.