JP2001179943A - Halftone dot inking controller and method for controlling halftone dot inking by the controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a halftone dot inking controller to obtain a printed product having a desired color tone without complicate setting of a target value even by replacing a printing item, sheet and ink real time and a method for controlling it. SOLUTION: The halftone dot inking controller comprises an ink film thickness measuring unit 200 for measuring the thickness of the ink film in an axial direction on a swing roller 27 made of a metal of an offset printer at each inking key, an ink supply amount control unit 300 for controlling an ink supply amount at each key width with a preset ink film thickness as a target value from the correlation between the thickness and a halftone dot inking degree based on the measured data, and a correcting means for correcting the deviation of the correlation generated due to a nip pressure unevenness by setting an inking roller at each key.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for controlling the amount of ink supplied to a general offset printing press, and more particularly, to a method for uniformly controlling an ink film thickness on an ink roller near a printing plate to obtain a desired color tone. The present invention relates to a dot deposition control device and a control method for the same.

[0002]

2. Description of the Related Art Conventionally, in offset printing, halftone dot deposition is controlled by the amount of ink supply. In color reproduction, especially in multicolor printing, it is important to balance the supply amount of each color ink. If this balance is lost, a desired color tone cannot be obtained.

The ink supply amount is adjusted by arranging a plurality of ink keys having a predetermined width in the paper width direction of the ink supply unit, that is, in the axial direction of an ink roller or the like. If the central portion in the width direction is insufficient in density, the opening degree of the ink key corresponding to that portion is increased to eliminate the insufficient density.

As described above, the adjustment of the ink supply amount is adjusted by the opening of the ink key, and has conventionally been performed manually. However, in recent years, the ink supply amount has been automatically adjusted with the development of measurement technology including various sensors. It has become.

[0005] As a conventional technology of the automatic control,
For example, it is disclosed in Japanese Patent Application Laid-Open No. 4-345851, which measures color information (density) on the paper surface immediately after printing and automatically controls the amount of ink supplied based on the color information by opening and closing an ink key. This is a color tone control device.

[0006]

However, in the above-described color tone control apparatus for printed matter, the density of the printed matter is controlled so that the ink key is controlled when a good printed matter to be controlled is obtained after printing to some extent. In the device that feeds back the measurement result, the feedback becomes slow,
As a result, there is a problem that the number of printing waste sheets increases.

Japanese Patent Laid-Open Publication No. Hei 10-272762 discloses a method for eliminating the above-mentioned delay in feedback, which measures the amount of ink at an arbitrary detection point on the surface of an ink roller and compares the detected value with the detected value. The print density adjusting device is configured to compare and calculate a preset target value or a preset target value at the detection point, and to control the supply amount of the ink by the opening of the ink key.

However, in the above-described print density adjusting device, the target value inputted in advance or the target value at the preset detection point is the pattern area ratio data, ink type, paper type, printing machine type, printing speed. , Water content, etc., and it has to be set every time the item to be printed, ie, the pattern area ratio, or the ink used changes. Furthermore, since there is no difference in the amount of ink on the roller surface due to the difference in the setting of the printing press, for example, the setting of the roller, there is a concern that the amount of ink on the roller surface may be different.

The present invention has been made to solve the above-mentioned problems of the prior art, and an object of the present invention is to provide an apparatus for controlling an ink supply amount in an offset printing press.
It is an object of the present invention to provide a halftone dot inking control device and a control method for realizing a printed material having a desired color tone without complicated setting of a target value even if the types of printing items and inks are changed.

[0010]

In order to achieve the above object, according to the present invention, first, the film thickness of ink in the axial direction on an ink roller of an offset printing machine is measured for each ink key width. Based on the ink film thickness measurement means and the ink film thickness measurement data, the ink supply amount is controlled for each ink key width with a predetermined ink film thickness as a target value from a correlation between the ink film thickness and the degree of dot coverage. And a correction means for correcting, for each ink key, a deviation in the correlation between the ink film thickness and the halftone dot deposition caused by a difference in setting of the printing press. It is a meat control device.

Further, in the invention according to claim 2, the ink roller is a roller near the printing plate and is a swing roller made of metal. It is.

Further, in the invention of claim 3, the value of the ink film thickness is a value obtained by an infrared sensor having absorption specific to ink and water, and the amount of water is added to the amount of ink. A halftone dot inlay control device according to claim 1 or 2.

[0013] In the invention of claim 4, according to claim 1,
Alternatively, using the dot-coating control device described in 2, the ink film thickness is measured for each ink key width in the axial direction on the ink roller, and based on the obtained ink film thickness data, the dot-coating of the printed matter is performed. And a correction means for correcting the dot non-uniformity due to a difference in machine setting when printing with a uniform film thickness in the width direction of the printed material for each ink key width. The halftone dot deposition control method is characterized in that the ink supply amount is controlled so as to make a correction and to achieve a film thickness target value preset for each ink key.

According to the above-described dot deposition control apparatus and dot deposition control method of the present invention, the ink supply amount can be controlled from the information on the film thickness on the roller without the information on the color tone of the printed matter, so that feedback is possible. And printing waste can be reduced as much as possible. In addition, since input information such as picture area ratio data of the item to be printed, ink type, paper type, etc. is not required for setting the target value for each print item,
Even if the printing item is changed, the same target value of the ink film thickness can always be set, the setting is not complicated, and the state of the roller setting etc. of the printing machine is included, so the obtained ink film can be obtained. The thickness data enables a reliable dot deposition control method.

[0015]

Embodiments of the present invention will be described below. As shown in the schematic side view of FIG. 1, the halftone dot inlay controlling apparatus of the present invention is, for example, a printing plate (2) of an offset printing press.
9) An infrared sensor (8) that measures the thickness of ink in the axial direction on the nearby swing roller (27) for each ink key width.
0) and a roller axial direction moving device (84) for moving it in the roller axial direction (84).
0) and the opening degree of the ink key (31) for each ink key width, with a predetermined ink film thickness as a target value based on the correlation between the ink film thickness and the dot coverage based on the ink film thickness measurement data. Key and ink source roller remote control device (86) for remotely controlling the amount of rotation of the source roller (32)
The difference between the ink supply amount control unit (300) and the correlation between the ink film thickness and the halftone dot thickness caused by the difference in the setting of the rollers of the printing press (for example, nip unevenness of the rollers) is determined for each ink key (31). And a correction means for performing correction on the dot.

Further, in the method for controlling dot deposition using the above-described dot deposition control apparatus, as shown in the schematic side view of FIG. 1, the method is applied to a surface of a plate cylinder (40) of an offset printing press, for example. Ink roller (2) in contact with printing plate (29)
6) The amount of ink on the metal swinging roller (27) above and the amount of water sent from the dampening water supply device (600) are applied because of the specific absorption of ink and water. The processing unit (8)
Measurement is performed while issuing a movement instruction from 2) to the roller axial movement device (84).

The ink roller whose ink film thickness is measured is limited to a metal swing roller (27), except that the ink roller (26) is used for the printing plate (2).
9) and because it has a metallic luster, it has high accuracy in absorbing and reflecting infrared rays. Other rubber ink rollers are separated from the printing plate (29), and This is in consideration of the fact that accurate and accurate data cannot be obtained due to variations in the color and color density of the roller.

The data measured above is processed by an arithmetic processing unit (82) so that the ink film thickness (target value) conforms to the paper density to be set, as shown in the graph of FIG. As shown in the enlarged schematic side view of FIG. 2, the opening degree of the ink key (31) of the ink supply device (500) is adjusted so that the ink supply amount is obtained from the relationship between the dot coverage and the ink film thickness. The distance (K) between the ink key (31) and the ink source roller (32) and the rotation amount of the ink source roller (32) are calculated. However, in the case of an ideal mechanical setting (setting of the ink roller group (100)), the correlation between the dot coverage and the ink film thickness as shown in the graph of FIG. 3 is obtained. In consideration of the fact that ideal machine settings are not always made, the deviation of the correlation between the ink film thickness and the density is corrected for each ink key width depending on the printing machine used.

Next, the calculated data of the opening degree of the ink key (31) and the rotation amount of the ink source roller (32) are passed to the ink key / ink source roller remote controller (86), and the ink key / ink source roller is controlled. The degree of opening of the ink key (31) and the amount of rotation of the ink source roller (32) are controlled by the remote control device (86) so that an appropriate halftone dot is formed on the printing paper.

As described above, the preset target value of the ink film thickness indicates a correlation between the obtained halftone dot deposition on the paper and the ink film thickness on the roller as shown in the graph of FIG. In the graph, the difference from the ideal setting in the machine setting (for example, unevenness in the part where the nip is partially weak in the roller, etc.) is corrected as a part of the target value, and the others can always be printed with the same setting Things.

That is, by making the ink film thickness in the roller axis direction on the swing roller uniform, the dot coverage in the width direction of the printing paper surface can be made constant. This means that it is not necessary to include the data of the pattern area ratio, the type of ink, and the like in the setting of the target value every time.

Since the above ink types are generally based on the reference colors of cyan, magenta and yellow, there is no need to change the ink type in particular. In some cases, in that case, it is necessary to enter the setting conditions, but since it is changed in a unit of several months to several years, there is usually no need to change it.

[0023]

As described above, the present invention has the following effects. That is, the halftone dot deposition control device of the present invention is based on the ink film thickness measurement means for measuring the ink film thickness in the axial direction on the ink roller of the offset printing machine for each ink key width, and based on the ink film thickness measurement data. The ink supply amount control means for controlling the ink supply amount for each ink key width by using a predetermined ink film thickness as a target value from the correlation between the ink film thickness and the dot coverage, and a difference in the printing press setting (ink roller Correction means for correcting the deviation of the correlation between the ink film thickness caused by the nip pressure unevenness of the ink and the degree of halftone dot deposition for each ink key. Even if there is no information on the color tone of the printed matter (picture area ratio, ink, etc.), the amount of ink supply can be controlled from the information on the film thickness on the roller, so the feedback to the ink supply device is fast, and printing loss is minimized. Rukoto can.

Further, since input information such as the pattern area ratio data of the item to be printed and the type of ink for each item to be printed is not required for setting the target value as described above, even if the printing item is changed, It is possible to always set the same target value of the ink film thickness, and it is possible to provide a halftone dot depositing control method that does not complicate the setting and thereby reduces the work of the operator.

Further, since the state of the roller setting of the printing press and the like, for example, the nip pressure unevenness of the roller are included in the target value setting, a highly accurate and reliable dot deposition control method can be realized.

Accordingly, the present invention exerts excellent practical effects as a halftone dot deposit control apparatus and a halftone dot deposit control method for an offset printing press.

[Brief description of the drawings]

FIG. 1 is a side view for explaining an embodiment of a halftone dot inlay control device of the present invention.

FIG. 2 is an enlarged side view of an ink supply unit included in an offset printing press for explaining an embodiment of a dot attachment control device of the present invention.

FIG. 3 is a graph showing the correlation between the dot coverage and the ink film thickness according to the present invention.

[Explanation of symbols]

 22 ‥‥ Water roller 26 ‥‥ Ink roller 27 ‥‥ Swing roller 29 ‥‥ Printing plate 30 ‥‥ Ink jar 31 ‥‥ Ink key 32 ‥‥ Ink source roller 40 ‥‥ Plate cylinder 42 ‥‥ Blanket cylinder 50 ‥‥ Ink 60 ‥‥ fountain solution 80 ‥‥ infrared sensor 82 ‥‥ calculator 84 ‥‥ roller axial movement device 86 ‥‥ ink key and ink source roller remote control device 100 ‥‥ ink roller group 200 ‥‥ ink film thickness control Unit 300 Ink supply control unit 500 Ink supply device 600 Dampening solution supply device K Distance between ink key and ink source roller

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) B41F 33/14 Z

Claims (4)

[Claims] 1. An ink film thickness measuring means for measuring an ink film thickness in an axial direction on an ink roller of an offset printing machine for each ink key width, and an ink film thickness and a halftone dot based on the ink film thickness measurement data. An ink supply amount control means for controlling an ink supply amount for each ink key width with a preset ink film thickness as a target value based on a correlation with the ink deposition; Correction means for correcting the deviation of the correlation for each ink key. 2. An apparatus according to claim 1, wherein said ink roller is a roller in the vicinity of a printing plate and is a swing roller made of metal. 3. The ink film according to claim 1, wherein the value of the ink film thickness is a value measured by an infrared sensor having absorption specific to ink and water, and the amount of water is added to the amount of ink. 2. The halftone dot inking control device according to 2. 4. An ink film thickness control device according to claim 1 or 2, wherein the ink film thickness is measured for each ink key width in the axial direction on the ink roller, and the ink film thickness data obtained is measured. The method according to claim 1, further comprising: controlling dot inlay of the printed matter based on a difference in mechanical setting when printing with uniform film thickness in a width direction of the printed matter. Is corrected by a correction means for each ink key width, and the ink supply amount is controlled so that a target film thickness set in advance for each ink key is obtained.