JP2831107B2 - Color control device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic control device applied to color tone control of a lithographic offset printing press.

[Conventional technology]

Conventionally, as shown in FIG. 6 and the control block diagram of FIG. 7, the density of only the solid portion 2 of the printed matter 1 is detected by the line type image camera 7, and the target solid portion density 3 The control unit (computer) 4 supplies a signal to an ink supply unit (ink key opening degree control unit) 5 to control the ink supply amount so that the deviation of the ink supply amount becomes zero.

[Problems to be solved by the invention]

1) As shown in FIGS. 2 (a) to 2 (d), the color tone of the print 1 is determined by the density change of the solid portion 2 and the halftone dot 6 of the print 1.
However, the density of both inks cannot be simultaneously adjusted to an appropriate value only by controlling the ink supply amount. This is because both of them change even when the amount of fountain solution supplied to the ink changes due to environmental fluctuations or the like.

2) As shown in FIG. 2 (d), the color tone (contrast) cannot be optimally controlled only by controlling the ink supply amount.

[Means for solving the problem]

By maintaining the density of the solid portion and the density of the halftone portion at the density of the target solid portion and the density of the halftone portion, respectively, the color tone is always properly maintained. For this reason, the following specific measures are taken.

1) A sensor for detecting the density of a solid portion and the density of a halftone dot portion of a printed matter is provided.

2) By a basic experiment, the density change characteristics of the solid portion and the halftone dot portion with respect to the change of the supply amount of the ink and the dampening solution as shown in FIGS. 2 (a) to 2 (d) are grasped, and based on the data, A multiple regression analysis formula for calculating the change in the supply amount of the ink and the dampening solution with respect to the change in the density of the solid portion and the halftone dot portion is obtained in advance.

3) The density of the target solid portion and the density of the halftone dot portion are compared with the density of the current solid portion and the density of the halftone dot portion, and the deviation value is calculated by the multiple regression equation obtained in the above 2). A signal for controlling the ink supply device and the dampening solution supply device is output based on the setting of the ink supply amount and the dampening solution supply amount appropriately for the supply amount and the dampening solution supply amount.

(Operation)

In advance, the density of the target solid portion and the density of the target point portion that maximizes the gradation are input to the control device, and the current density of the solid portion and the density of the halftone dot portion sent from the sensor are compared with the target value. The ink supply amount and the dampening water supply amount change are set by comparing and calculating based on the density change characteristics of the solid portion and the halftone dot portion with respect to the ink supply amount and the dampening solution supply amount change. By supplying a signal to the dampening water supply device and changing each supply amount, control is performed so that the color tone always has an appropriate value.

〔Example〕

An embodiment of the present invention will be described with reference to FIGS. In the figure, 1 is a printed matter, 2 is a solid portion, 3 is a target solid portion density, 4 is a control device (computer), 5 is an ink supply device (ink key opening degree control device), 6 is a halftone dot portion, and 7 is a dot portion. Line type image camera, 8 is the key width, 9 is the mouth, 10 is the butt, 11 is the patch, 12 is the image memory, 13 is the target halftone dot density, 14 is the dampening water supply device (water roller rotation amount control device) ).

1) By a basic experiment, the density change characteristics of the solid portion and the halftone dot portion with respect to the change of the supply amount of the ink and the dampening solution as shown in FIGS. 2 (a) to 2 (d) are grasped, and based on the data, , A multiple regression analysis formula for calculating the ink supply amount and the dampening solution supply change with respect to the density change of the solid portion and the halftone dot portion is obtained in advance, and the multiple regression formula for the density change characteristic is calculated by the control device 4.
To memorize.

2) As shown in FIG. 3, the proper density of the solid portion 2 and the halftone dot portion 6 (portion where colors are not mixed, that is, the color to be controlled, The target density of the halftone dot portion 6 which exists only is input to the control device 4 (the key width 8 where the solid portion 2 and the halftone dot portion 6 do not exist is the solid portion 2 and the halftone dot portion at the edge 9 or the tail 10 of the printed matter 1). The patch 11 of the part 6 is provided in advance).

3) As shown in FIG. 4, the density in the width direction of the printed matter 1 being operated is measured in the vertical direction by the line type image camera 7 and stored in the image memory 12 in the control device 4.

4) The density of the solid portion 2 and the density of the halftone dot portion 6 at the position designated in the above item 1) are retrieved from the image memory 12 for each key width 8, and the target solid partial density 3 and the target halftone dot density 13 are retrieved.
Compare with

5) These deviation values are obtained by comparison in the above item 4), and the deviation values are obtained from the density changes of the solid portion 2 and the halftone dot portion 6 preset in the control device 4 in the item 1). An appropriate signal is given to the ink supply device 5 and the dampening water supply device 14 by substituting into the multiple regression equation for estimating the change in the dampening water supply amount.

6) A signal is sent from the control device to the ink supply device 5 and the dampening solution supply device 14 until the deviation value becomes zero, and the ink supply amount and the dampening solution supply amount are always kept properly.

FIG. 5 is a block diagram showing the above tone control process.

〔The invention's effect〕

The color tone control device according to the present invention includes means for detecting the density of a solid portion and a halftone portion of a printed matter, and a density change characteristic of a solid portion and a halftone portion with respect to a change in an ink supply amount and a dampening solution supply amount. The input density of the target solid portion and the halftone dot portion are compared with the density of the solid portion and the halftone portion of the printed matter obtained by the detection means to calculate the ink supply amount and the dampening solution supply amount change. Means and means for controlling the ink supply amount and the dampening solution supply amount based on the result of the comparison operation have the following effects.

1) The color tone and gradation of the printed matter are influenced by the density change of the solid portion and the halftone dot portion of the printed matter. In the present invention, both the ink supply amount and the dampening solution supply amount are determined based on the density characteristic change. Since the control is performed at the same time, the concentrations of the two can be simultaneously set to the appropriate values.

[Brief description of the drawings]

FIG. 1 is a schematic layout diagram of a color tone control device according to an embodiment of the present invention, and FIGS. 2 (a) to 2 (d) show changes in solid partial density and halftone dot density based on changes in ink and dampening solution supply amounts. FIG. 3 is a graph showing the appropriate solid partial density and halftone dot density inputted to the control device, and FIG. 4 is a graph showing the paper surface density during operation of the printing press by a line image camera. FIG. 5 shows a mechanism for outputting to the internal image memory, FIG. 5 is a color tone control block diagram according to the present invention, FIG. 6 is a schematic layout diagram showing a conventional color tone control device, and FIG. 7 is a conventional color tone control block line. FIG. 1 Printed matter 2 Solid area 3 Target solid area density 4 Control unit 5 Ink supply device 6 Halftone area 7 Line image camera 13 Target halftone area Concentration 14 ... Dampening water supply device

──────────────────────────────────────────────────続 き Continuation of front page (72) Inventor Masahito Kaneko 4-6-22 Kannon Shinmachi, Nishi-ku, Hiroshima-shi, Hiroshima Mitsubishi Heavy Industries, Ltd. Hiroshima Research Laboratory (56) References JP-A-64-67342 (JP, A) JP-A-63-166541 (JP, A) JP-A-61-40159 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) B41F 7/24, 31/02, 33/10

Claims (1)

(57) [Claims] 1. A means for detecting the density of a solid portion and a halftone dot portion of a printed matter, and a pre-input based on a density change characteristic of the solid portion and a halftone portion with respect to a change of an ink supply amount and a dampening solution supply amount. Means for comparing the density of the target solid portion and the halftone dot portion with the density of the solid portion and the halftone dot portion of the printed matter obtained by the detection means to set the ink supply amount and the dampening solution supply amount change; Means for controlling an ink supply amount and a dampening solution supply amount based on a result of the comparison operation.