SU923888A1 - Method of monitoring triad synthesis of colour in the one-run printing process - Google Patents

Description

The invention relates to the printing industry and can be used to print color data when controlling triad color synthesis on an imprint to normalize color reproduction.

There is a method of controlling the triad synthesis of color on the print during the printing process by measuring the zonal optical density of monochromatic marks on the print.

By a known method with four-color printing in one pass on the print field, monochromatic color marks are printed and the optical density behind the light filter corresponding to the absorption zone of the desired paint is measured by these marks, followed by correction of the ink supply. When printing with the sequence of overlapping inks: yellow, magenta, cyan, black — in the first section of the print field, the label is printed with yellow paint. Using a densitometric device in the printing process

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measure the value of the zonal optical density of the yellow paint behind the blue filter, compare it with the specified value and in case of deviation regulate the ink supply to achieve the specified value of ⁵ .

Acting in a similar way, in the second section on the print of the print print the mark in purple ink, measuring the magnitude of the zonal optical density

purple paint behind the green light filter. In the third section, on the print, the mark is printed with blue paint, measuring the value of the zone optical density of the blue paint behind the red light filter. In the fourth section, print the mark in black, measuring

zonal optical density of the black paint behind the filter visibility £ ΐ).

20 However, the known method does not take into account the color distortion of binary

colors of the synthesis process, does not take into account

very, significant differences in the transition of paint directly to the printed

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923888

four

paper and paint on paint with multi-color printing in one pass, especially on web offset machines. Besides; This method does not take into account the dependence of the color of binary prints on the sequence of application with insufficient transparency of paints.

The purpose of the invention is to improve the accuracy of control.

In order to achieve this goal, in the imprint process of color synthesis on the imprint, in the printing process, binary marks are applied to the imprint field (binary marks are used in test objects to control the printing process), the values of three zonal reflection densities of each binary mark D ^КР are measured , D ^ ^{e /} ) D ^Sin , calculate their color tone (T) according to the formula D ^SII - D ^{3 eL}

⁷ "dzel. dcr '

ten

15

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determine the magnitude and sign of the color tone deviation of two of the three binary tags from set values ₂₅ and Adjustments ruyut supplying ink to a desired predetermined hue restoration.

To implement the proposed method, an oblique coordinate system can be used, based on wa-densitometric measurements of samples in three zones of the visible spectrum. The graph of such a zonal system (Fig. 1) is an equilateral hexagon. Hexagon vertices correspond to the primary (blue, Pur ³⁵ lurnomu, yellow) and binary (red, green, blue) color triad avtotipnogo synthesis for ideal paint. Ideal colors are characterized by the fact that the optical density in the reflecting zones ⁽ 'Lives-D ₀ = O, and in the absorption zones D _{# 0?} ~ SOP5f, their priority is such that the additional colors are on mutually opposite vertices. The coordinates of this graph ⁴⁵

essence (D _s - D ₃ ) and (D3 - Dk), where D _o D e £ and D c - zonal densities of samples in the blue, green and red zones. The coordinate axes are located at an angle of 60 °.

The axis (D _s - D ^) passes through the vertices, 5o corresponding to the ideal yellow and blue colors, and the horizontal axis (Dz ~ Dz) passes through the vertices, corresponding to the ideal blue and red colors. Neutral colors By arranging ⁵ Laga in the center of the graph.

Finding the point corresponding to the sample on the graph is carried out according to

measurements of the three zonal densities and calculations of the zonal parameters using the above formula.

Example 1. A triad of inks is printed with the sequence of superposition: yellow, magenta, and blue. In the first section of the print field, three adjacent labels are printed with yellow paint. The first label is used to control and adjust the flow of yellow paint in the usual manner. results of measurement of the density of the reflection of the label for the blue filter. In the second section, purple ink is printed on the second yellow mark; a binary red mark is obtained. · Measure the three zonal reflection densities of the red mark.

The specified values of the zonal densities of the binary red standard are: De ^MN - 1.80 ^{GD 3EL} = 1.69; ~ D * ^P =

“0.11. In this case, the color standard is dSMM_ d ^ ^l

- r + 0.07.

green * cr

A- -A

Let the values of the measured dense ^cmn = 1.80; “D ^green

they are equal to:

D ^ ^P = 0.11. Then

1.30;

d ^c ; ⁿ -dG,

A * ^ate -A * ^p '

4, ao-4, eo

1, EO-0, and

= + 0.41.

The obtained value of T, must be compared with the value of the color tone of a given standard of binary red.

As can be seen from FIG. 1, the color tone of the measured red mark (point 1) deviated from the reference towards the yellow, which indicates the need to increase the supply of magenta paint to establish the color tone of the standard. The magnitude of the deviation is DT = T _and - T _e «= 0.42-0.07 = + 0.35.

^PRI mme ^R 2. Now let the values of the measured densities be: D? ^ ^ICH = = 1.80GD ^ ^eL »1.85GD ^ ^P = 0.11. ^£ Then

_t

“ΏΤ - 0.40.

1.90-1.65

1.05-0.11

= -0,0¾

As can be seen from FIG. 1, the color tone of the measured red mark (point 2) deviated from the reference toward the magenta side, which indicates an excess of magenta ink to achieve the specified color tone value Td = 0.07.

Thus, the proposed method allows you to accurately control the process color synthesis on the print during the printing process and thereby precisely control the flow of ink to achieve a given 5 color tone value.

Claims (1)

Claim The method of controlling the triad of color synthesis on the print in the process of printing in one pass, including the sequential imposition of color check marks - on the print of the print, the measurement of the zonal reflection densities of the check marks and the correction of the border color * ⁵ juice according to measurement results, characterized in that, with a chain of increasing the accuracy of control, binary marks of triad paints are used as color reference marks, while measuring the zonal densities reflections are carried out on any two binary labels.