JP2003285421A - Printing method and printing color control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a printing method for controlling an ink key by measuring a control strip for measuring quality provided in the surface of printing paper by a measuring instrument, shortening a time required until finished print (printed matter becoming a commodity) is obtained through the process from initial printing until printing is completed, and a printing color control device. <P>SOLUTION: At the beginning of printing, control considering the balance of C, M and Y is performed and, after the printed matter becoming the commodity is formed and printing becomes stable, this control is changed over to simple control for allowing each of colors K, C, M and Y to approach a target value independently. For example, by performing the control considering the balance of C, M and Y once per 3,000 printing papers, the printed matter wherein densities of respective colors enter an allowable range and quality is stable can be formed while keeping the balance of C, M and Y. The printing color control device is also disclosed. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention includes a control strip for measuring quality in a printing paper surface,
The present invention relates to a printing method and a printing color control apparatus for controlling an ink key by measuring the control strip with a measuring instrument.

[0002]

2. Description of the Related Art In offset printing, black, indigo, red and yellow (hereinafter K, C,
Printing that controls the ink key by providing a control strip containing a patch (color chart) for inspecting each ink amount and measuring the control strip with a measuring instrument. The method is
Due to space issues on paper, it is often used in sheet-fed printing presses, and rarely used in offset rotary printing presses (hereinafter referred to as "off-wheels"), but recent demands for printed matter Due to the strict quality
The application of quality control methods using strips has been investigated, and in order to solve the problem of space on the paper, an instrument capable of measuring a very thin control strip has been developed and is now in use.

In practice, there is a method of controlling each color independently using a patch of K, C, M, and Y monochromatic solid densities. This is because the density value of each color is There is an advantage that the response speed until reaching the target value is fast,
Since the control is performed for each single color, when looking at the actual pattern expressed in gray scale, it sometimes took time until it became a regular paper, and the color balance sometimes collapsed.

The control strip has a C,
There is also a method of performing control by using a gray color composed of a mesh of M, Y and three colors, and in this case, K, C, M, Y, 4 which are the basic colors of printing. It has been found that compared to the method of inspecting only the color ink amount, the amount of information regarding the printed pattern is large, and as a result, the quality of the printed matter is more stable. However, since the amount of information is large, the response speed tends to be delayed.

On the other hand, the balance of the ink amounts of C, M, Y, and 3 colors has a great influence on the print quality because it affects the hue reproduced by the 3 colors, and attention is paid to this point, Two
In Japanese Patent Laid-Open No. 001-80052, it is disclosed that a printed matter reproduced closer to a color sample can be obtained by performing control in consideration of the balance of C, M, Y and three colors while measuring patches for each single color. ing.

[0006]

The problem to be solved by the present invention is to put a control strip for measuring quality in the printing paper surface and measure the control strip with a measuring instrument to remove the ink key. It is an object of the present invention to provide a printing method and a printing color control device capable of printing a good printed matter until the end of printing in a short time from the start of printing to a regular paper (printed matter to be a product) in the controlled printing method. And

[0007]

The first invention of the present invention which solves the above-mentioned problems is K, C, M, which is the basic color of printing.
Y, a control strip containing a patch for inspecting the amount of each ink is provided in the printing paper surface, and the control strip is measured by a measuring instrument to control the ink keys. , K and C, M and Y, one of the colors has a preset reference value as a target value, and the other two colors are obtained by calculating the balance of the three colors from the C, M and Y patch measurement results. The ink key is controlled with the value as the target value, and after C, M, and Y are within the allowable range of the target value, the ink key control that individually approaches each color of K, C, M, and Y is switched to the target value, and periodically. The printing method is characterized by confirming the balance of C, M, and Y colors.

A second aspect of the present invention is to provide a control strip containing a patch for inspecting the ink amount of each of K, C, M and Y, which are the basic colors of printing, in the printing paper surface. In the printing method of controlling the ink key by measuring the control strip with a measuring device, at the beginning of printing, any one of K, C, M, and Y has a reference value set in advance as a target value, For the other two colors, the ink key is controlled with the value obtained by calculating the balance of the three colors from the C, M, Y patch measurement results as the target value,
After C, M and Y are within the allowable range of the target value, K, C,
The printing method is characterized in that the M and Y colors are individually switched to ink key control to bring them closer to a target value, and the ink key control is performed periodically in consideration of the balance of the three C, M, and Y colors.

Further, according to a third aspect of the present invention, at the beginning of the printing, one color other than K having a reference value set in advance as a target value is C, and C is one color.
The printing method described in 1.

Further, a fourth aspect of the present invention comprises a patch density measuring means for measuring the density of a patch provided with a control strip on the printing paper surface, and the ink key control according to any one of claims 1 to 3. The printing color control device is provided with an ink key control means for performing the operation.

As described above, according to the printing method of the present invention, when the density of C is used as a reference at the beginning of printing, M
By controlling the ink amount targeting the density value that satisfies the balance index, Y and Y can balance C, M, Y, and 3 colors, and it is possible to produce a printed matter with a close color reproducibility. You can match the most sensitive hues. Next, in order to bring the printed matter to be controlled closer to the target, the density of each color is within the target allowable range by controlling the density of each color together with the balance of C, M, Y and 3 colors. become. As a result, the lightness and saturation, which are called the "strength" of the color, become close to the target printed matter, and the target printed matter is obtained.

[0012]

DETAILED DESCRIPTION OF THE INVENTION The printing method of the present invention will be described in detail with reference to the drawings. FIG. 1 is an explanatory diagram showing the densities of the respective colors used in the respective printing steps in one embodiment of the printing method of the present invention. Although the density of each color is used as the control factor here, other colors that can be represented by CIELAB or the like may be used as the control factor.

In the printing method of the present invention, control is performed in consideration of the balance of C, M, and Y at the beginning of printing, and after the printed matter to be a product is prepared and stabilized, K, C, M, and
Y, switching to simple control in which each color is independently approached to the target value. Then, for example, once every 3000 sheets, C,
By controlling in consideration of the balance of M and Y,
While maintaining the balance of C, M, and Y, the density of each color falls within an allowable range, and a printed matter with stable quality can be manufactured.

First, K is independently managed from the start to the end of printing according to a preset reference density. By doing this, (1) productivity is improved because the time and paper required for black color matching are reduced. (2) Since the black density does not depend on the operator, variations in the black density are not seen between lots or within the surface of one printed matter, so that the print quality is improved. (3) Since an appropriate black ink is supplied onto the black plate, the black ink is overfilled and the shadow portion of the black ink is not crushed, or the black ink is insufficient and the black ink density does not decrease. The gradation in the shadow area becomes rich and the print quality improves. There is such an action. In the following, C, M and Y excluding K will be described in due course.

At the beginning of printing, C controls the ink key opening aiming at the reference density, and M and Y are C,
From the patch measurement results of M and Y, the density value satisfying the balance index based on the density of C is obtained, and the ink amount is controlled with this value as a target. At this time, of the three colors,
The color controlled by the reference density may be M or Y, but it is preferable to use C.

As shown in FIG. 2, it is C in a single color.
The reflectance of the wavelength of (cyan) is different from that of other M (magenta) and Y.
Since it is lower than that of (yellow), it is necessary to control the density in consideration of the densities of M and Y. In addition, monochromatic M
Since the reflectance of the wavelength is sufficiently higher than that of C, it is not necessary to consider C, but Y needs to be considered. Further, the reflectance of the monochromatic Y wavelength is sufficiently high, and it is not necessary to consider both M and C. Therefore, if C is determined first, only M and Y need to be considered, control is easy, and the target value is reached quickly.

Here, the balance index means C, M, Y,
It is important to use an equation sensitive to changes in the balance of the three colors. For example, the following equation is used here. Balance index BA = Dy (Dm-Dy) / Dc (Dc
-Dm) where BA: balance index Dc: patch density of cyan Dm: patch density of magenta Dy: patch density of yellow. As a result, the C, M, Y, and 3 colors are balanced, and a printed matter having a close visual color reproducibility can be produced at an early stage.

From the balance of C, M, Y and 3 colors and the density of each of them being within the allowable range, the printed matter becomes a product,
At the stage of product printing, after that, the control is switched to a simple control in which each of C, M, Y, and each color is independently approached to the target value. This simplifies the control logic that controls the ink key opening and adjusts the ink key opening after measuring each color patch on the color bar.
The response speed until the density value of each color approaches the target becomes faster. Therefore, the “strength” of each color, that is, the lightness and the saturation, approaches the standard. Here, the densities obtained from the patch measurement for all of C, M, Y, and three colors are set as the target densities.
The control at the reference concentration may be performed subsequently.

Next, for example, the balance of C, M, and Y is checked at a timing of once for every 3000 sheets. As a result, if the balance of the three colors is not within the allowable range, the control for each single color is stopped. , Control is again performed in consideration of the balance of the three colors.
It is desirable that the timing of performing control in consideration of the balance of C, M, and Y is appropriately set according to the state of the printing press, the management regulations of the printing factory, or the contract with the customer.
This keeps the balance of C, M and Y,
It is possible to produce a printed matter of stable quality in which the density of each color is within the allowable range. Here, the control considering the balance of the three colors is performed after confirming the balance of the three colors, but the control may be performed periodically and forcibly considering the balance of the three colors.

The control strip for measuring the quality provided in the printing paper surface may be placed at any position in the printing paper surface. This arbitrary position is the part that will be cut when the final magazine or book is created in the bookbinding process,
It is a blank part without a pattern.

Further, in the case of offset printing, the adjustment of the ink amount is performed by the opening amount of the blade divided along the printing flow direction. Can not get the information of the design. Therefore, it is preferable to dispose a patch for inspecting the ink amounts of K, C, M, Y, and four colors, which are the basic colors of printing, for each blade, but the invention is not necessarily limited to this. .

Next, the printing color control device will be described with reference to FIG. FIG. 3 is a schematic view of a printing machine illustrating an embodiment of the printing color control device of the present invention. The printing color control device of the present invention is provided with a measuring head 25 as a patch density measuring means.
And one of K, C, M, and Y has a reference value set in advance as a target value, and the other two colors are obtained by calculating the balance of three colors from the patch measurement results of C, M, and Y, respectively. Output the signal to control the ink key with the specified value as the target value, C, M,
After Y is within the allowable range of the target value, K, C, M, Y
A color management control device 20 as a device that outputs an ink key control signal for individually bringing each color closer to a target value or periodically checks the balance of C, M, and Y colors, and a signal from the color management control device. And an ink amount control device 17 for actually adjusting the opening of the ink key.

[0023]

By the use of the printing method according to the present invention, at the beginning of printing, one of K, C, M and Y has a reference value set in advance as a target value, and the other two colors have C, M and The ink key is controlled with the value obtained by calculating the balance of the three colors from the patch measurement results of Y as the target value, and after C, M, and Y are within the allowable range of the target value, K, C, M, and Y In addition to switching to ink key control that individually brings each color closer to the target value,
Since the balance of C, M, and Y colors is regularly checked, it takes only a short time from the beginning of printing to the original paper (printed product), and the good printed product can be printed until the end of printing. Play. As a side effect, it leads to reduction of printing paper and ink used, and the total printing time can be shortened.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing densities of respective colors used in respective printing stages in an embodiment of a printing method of the present invention.

FIG. 2 is a characteristic diagram of commonly used printing inks C, M and Y.

FIG. 3 is a schematic view of a printing machine illustrating an embodiment of a printing color control device of the present invention.

[Explanation of symbols]

10 ... K unit 11 ... C unit 12 ... M unit 13 ... Y unit 14 ... Blanket body 15 ... plate cylinder 16 ... Ink roller 17 ... Ink amount control device 18 ... Printing paper 20 ... Color management control device 25 ... Measuring head 26 ... Colorimetric data

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) H04N 1/60 H04N 1/46 ZF term (reference) 2C250 EA23 EB23 5C074 BB16 DD24 EE20 FF15 HH04 5C077 LL11 LL18 LL19 MM27 MP08 PP33 PP37 TT08 5C079 HA18 HB03 KA15 LA02 LA23 MA10 NA03 NA11 PA07

Claims (4)

[Claims] 1. A control strip provided with a patch for inspecting K, C, M, Y, which is a basic color of printing, for each ink amount is provided in a printing paper surface, and the control strip is a measuring instrument. In the printing method in which the ink key is controlled by measuring with, at the beginning of printing, one of K, C, M, and Y has a reference value set in advance as a target value, and the other two colors have C and M. ,
The ink key is controlled with the value obtained by calculating the balance of the three colors from the Y patch measurement results as the target value, and after C, M, and Y are within the target value allowable range, K, C, and
A printing method characterized by switching to ink key control for individually approaching each of the M and Y colors to a target value and periodically checking the balance of the three colors of C, M and Y. 2. A control strip containing a patch for inspecting the ink amounts of K, C, M, and Y, which are the basic colors of printing, is provided in the printing paper surface, and the control strip is provided.
In the printing method in which the ink key is controlled by measuring the strip with a measuring instrument, at the beginning of printing, any one of K, C, M, and Y has a reference value set in advance as a target value and the other two colors. Is C, M,
The ink key is controlled with the value obtained by calculating the balance of the three colors from the Y patch measurement results as the target value, and after C, M, and Y are within the target value allowable range, K, C, and
A printing method characterized by switching to ink key control for individually approaching each of the M and Y colors to a target value and periodically performing ink key control in consideration of the balance of the three colors of C, M and Y. 3. The printing method according to claim 1, wherein at the start of printing, one color other than K having a preset reference value as a target value is C. 4. A patch density measuring means for measuring the density of a patch provided with a control strip within a printing paper surface,
A printing color control device comprising an ink key control means for performing the ink key control according to claim 1.