JP4228855B2 - Ink key control method, ink key control device, and offset printing machine - Google Patents

Description

The present invention relates to a method and an apparatus that are applied to offset printing and that are obtained by measuring the color density on the printing paper surface and control the opening of the ink key so that the color density becomes an arbitrary color density. Is obtained by measuring the color density of the patch arranged in the width direction on the margin on the printing paper, and controls the opening of the ink key so that the color density becomes an arbitrary color density, and The present invention relates to an offset printing machine.

  Conventional methods for determining the opening of the ink key so as to obtain the desired color density by measuring the color density on the printing paper surface are roughly classified into two types. One is a method and apparatus for determining the color density of a pattern on a printing paper surface and controlling the opening of an ink key so that the color density becomes an arbitrary color density. The other is a method and apparatus for controlling the opening of the ink key so that the color density of the patch placed in the margin on the printing paper surface is measured and the color density becomes an arbitrary color density. It was.

  Since the former measures the color density of the pattern, it is effective for pattern management for the purpose of maintaining the color tone of the pattern. However, since the design of the halftone dot area ratio of the pattern to be measured varies from time to time, the color density of the pattern to be measured can be grasped to what extent the desired color density is before starting printing. Since it is difficult, application to color matching at the start of printing, which is one of the merits of such a control device, has been difficult.

  Since the latter measures and controls the color density of the patch attached to the margin of the printed material, it is possible to obtain the color density of any halftone dot area ratio for any item. For this reason, it is relatively easy to grasp the desired color density before the start of printing than when measuring and controlling the color density of the pattern. Application is under consideration and it has been put to practical use overseas.

  However, since the location being measured is not a pattern, for example, the influence of density unevenness in the flow direction has appeared remarkably. Specifically, although the color density of the patch to be measured has changed at a desired color density, the color density of the pattern portion may have changed at a color density lower than the desired color density.

  The phenomenon called unevenness is a common problem in the field of coating and image formation, and various methods have been proposed to reduce it, but the effect of density unevenness applicable to offset printing is reduced. No method has been proposed.

  For example, Patent Document 1 does not mention the density unevenness in the vertical direction peculiar to offset printing. As described above, “the color density of the patch to be measured is changed at a desired color density, but the color density of the pattern portion is changed. Cannot be applied to the problem that “the color transition is lower than the desired color density”.

JP 2001-260407 A

  The present invention has been made in consideration of such a technical background, and is obtained by measuring the color density on the printing paper surface in offset printing, and the ink key so that the color density becomes an arbitrary color density. In more detail, the method and apparatus for controlling the opening degree of the image are determined by measuring the color density of the patch arranged in the width direction in the margin on the printing paper so that the color density becomes an arbitrary color density. In addition, regarding a method and apparatus for controlling the opening degree of the ink key, a method for reducing the influence of density unevenness in the flow direction is proposed.

The first invention of the present invention aimed at solving the above problems is an ink key control method for controlling the opening of an ink key based on information obtained by measuring a patch provided on a printing paper surface.
A measurement stage for measuring the color density of the patches provided in the flow direction and width direction on the printing paper surface,
A prediction step of predicting the overall color density on the printing paper surface from the measurement result of the patch ;
A control floor for controlling the opening of the ink key based on the predicted color density on the printing paper surface,
Is an ink key control method.

  According to a second aspect of the present invention, there is provided the ink key control method according to claim 1, wherein the control stage controls the predicted average color density on the printing paper surface to be a desired color density.

Further, the third invention of the present invention is an ink key control device for controlling the opening of an ink key based on information obtained by measuring a patch provided on a printing paper surface.
Measuring means for measuring the color density of patches provided in the flow direction and width direction on the surface of the printing paper;
Prediction means for predicting the overall color density on the printing paper surface from the measurement result of the patch ,
Control means for controlling the opening of the ink key based on the predicted color density on the printing paper surface,
Is an ink key control device.

  According to a fourth aspect of the present invention, there is provided the ink key control apparatus according to claim 3, wherein the control means controls the average color density of the predicted color density on the printing paper surface to be a desired color density.

  This makes it possible to consider the influence of density unevenness in the flow direction, which has been a problem by measuring and controlling the color density of the patch attached to the margin of the printed material.

  According to a fifth aspect of the present invention, there is provided an offset printing machine comprising the ink key control device according to the third or fourth aspect.

  As a result, even though the color density of the patch attached to the margin of the printed material is measured and controlled, the influence of density unevenness can be reduced on the system, and the picture quality is improved.

  As described above, according to the present invention, in offset printing, the color density of the patch arranged in the width direction and the patch arranged in the flow direction in the margin on the printing paper surface is measured during printing. Therefore, the opening degree of the ink key is controlled so that the color density becomes an arbitrary color density, so that the influence of density unevenness in the flow direction can be reduced.

Hereinafter, details of the present invention will be described with reference to the drawings.
However, the following content is one embodiment and an example, and does not limit the scope of the claims of the present invention.

  FIG. 1 is a schematic view showing an example of an offset rotary press according to the present invention. The printing unit 10 includes a black (K) unit 11, an indigo (C) unit 12, a red (M) unit 13, and a yellow (Y) unit 14, and a printing paper 15 between the upper and lower cylinders of each color unit. It is configured to print through.

The printing unit 10 is equipped with an ink key opening degree control device 20 having a measuring camera 22 and an arithmetic unit 21, and the ink key opening degree control device 20 opens the ink key of the printing unit 10 via a cable 23. Control the degree.

  FIG. 2 shows an example of a color density control method using the present invention. First, a step 61 for printing a patch in the width direction and the flow direction of printing in a blank portion of the plate, and ink key opening control in parallel with the step 61. Based on step 62 in which the desired color density is set as the target density in the apparatus, the process proceeds to the printing start step.

  At this time, since the position where the patch is burned cannot be provided in the pattern portion, it becomes a blank portion. However, in this case, it is not always necessary to provide a patch arranged in the flow direction in the margin portion along the flow direction of the pattern portion. Similarly, there is no need to provide a patch arranged in the width direction in the margin portion along the width direction, but since it is easy to visually confirm, the patch is arranged in the flow direction in the margin portion along the flow direction of the pattern portion. In many cases, a patch arranged in the width direction is provided in a margin part along the width direction. Of course, it is also possible to provide an arrangement place in any margin for the convenience of the sensor.

  After printing is started, the color of the patches arranged in the width direction is passed through step 64 in which the ink key opening control device controls the ink key opening so that the color density of the patches arranged in the width direction becomes a desired color density. The process proceeds to step 65 where it is determined whether the density has reached a desired allowable range (desired color density + allowable width).

  In step 65, if the judged result is NG, the process returns to step 64. If OK, the color density of the patches arranged in the flow direction is measured during printing, and the process goes to step 66 for grasping the state of the color density in the flow direction. . Note that step 66 is performed in combination with a measuring unit mounted on the ink key opening control device.

  Specifically, the measuring unit moves while moving in the width direction while the ink key opening control device controls the ink key opening so that the color density of the patches arranged in the width direction becomes a desired color density. The color density of the patches arranged in the width direction is measured. At the stage of reaching Step 66, the color density of the patches arranged in the flow direction is temporarily switched to an apparatus for measuring the color density. The patch is moved to a measurable position, and the color density of the patches arranged in the flow direction is measured.

  The measurement time is about 1 second. During this time, if the printing speed of the printing press is 500 [rpm], the number of printed materials passing under the measurement section is a little over 8 copies. The color density of patches arranged in the flow direction can be measured. Note that it is also possible to provide a dedicated measuring device for measuring the color density of the patches arranged in the flow direction. In this case, although a cost is generated, more accurate information can be acquired because the measurement function is enhanced.

  After the above steps, the color density of the patches arranged in the width direction and the flow direction can be grasped. Therefore, the process proceeds to step 67 for virtually calculating the color density of the entire surface on the printing paper, and finally the flow direction is determined. Proceed to step 68 in which the target density is given to the ink key opening control device so that the color density becomes the desired color density. Subsequent processes are printed through the same processes as in the prior art.

  By using the present invention described above, density unevenness in the flow direction, which has not been considered in the past, can be taken into account. Therefore, density unevenness in the flow direction that appeared in the pattern portion due to the fact that the location being measured is not a pattern. The influence of can be reduced.

  FIG. 3 shows the result of printing using the plate through step 61 in which patches are printed in the width direction and the printing flow direction in the blank portion of the plate in FIG. 2, 91 is printing paper, and 92 is the width. Patches arranged in the direction, 93 is a patch arranged in the flow direction, and 94 to 101 are picture portions.

  In the patches 92 and 93, four color patches 92K, 92C, 92M, 92Y, 93K, 93C, 93M, and 93Y are repeatedly provided in the width direction and the flow direction, and each patch is 80% of the color density of the corresponding pattern portion. It is a patch.

  On the other hand, FIG. 4 shows a conventionally proposed method. Conventionally, based on step 140 in which patches are printed in the width direction on the blank portion of the plate and step 141 in which a desired color density is set as a target density to the ink key opening control device in parallel with the step, the process proceeds to step 142 for starting printing. move on. After printing is started, the process proceeds to step 143 where the ink key opening control device controls the ink key opening so that the color density of the patches arranged in the width direction becomes a desired color density.

  With this method, although the color density of the patches arranged in the width direction changes at a desired color density, the color density of the pattern portion may change at a color density lower than the desired color density. It was. This method is hereinafter referred to as a conventional method.

  For reference, FIG. 5 shows the result of printing using the conventional method using a plate through step 140 in which patches are burned into the blank portion of FIG. 4, with 160 being printed paper and 161 being arranged in the width direction. Patches 162 to 169 are design parts.

  In the patch 161, four color patches 161K, 161C, 161M, and 161Y are repeatedly provided in the width direction, and each patch is an 80% patch of the color density of the corresponding pattern portion.

Here, one embodiment of the present invention implemented according to the procedure shown in FIG. 2 and the results thereof are shown. As an implementation procedure, first, a BT full-size BB offset manufactured by Mitsubishi Heavy Industries, Ltd. equipped with an ink key opening control device as a test machine. A rotary press was selected.

  In the prepared version, Standard Color Image Data (hereinafter referred to as SCID) is laid out in the pattern portion, and a single color 80% patch is laid out in the blank portion as shown in FIG.

  The desired color density was set to [K C MY] = [1.00 0.95 0.90 0.85], and the allowable width was set to ± 0.10 for each color, and set to the ink key opening control device. After the above preparation, printing was started. The course of going through all the steps was as follows.

0 min 00 sec Start of printing press, speed up, fixed at 500 rpm, ink on 1 min 00 sec. Ink key opening control device adjusts color density of patches arranged in width direction to desired color density Start control of ink key opening 2:00 pm Confirm that the color density of the patches arranged in the width direction has reached the desired tolerance (desired color density + tolerance) Color density of the patches arranged in the flow direction Is measured during printing and the color density state in the flow direction is grasped. From these results, the color density on the printing paper surface is virtually calculated (eg, black, see FIG. 6). The average color density in the flow direction is the desired color. The next target density was given to the ink key opening degree control device so as to obtain a density [K C MY] = [1.04 0.99 0.94 0.89]
3 min 00 sec The average color density in the flow direction reaches the desired color density (example: black, see Fig. 7)
As a result, according to the present invention, the influence of density unevenness in the flow direction on the pattern could be reduced.

Specifically, the visual evaluation of the SCID pattern was good because the color density of the pattern portion was changing near the desired color density. Of course, in place of such quantitative correction (+0.04), quantitative correction and other corrections can be appropriately selected depending on the application.

Here, one example of the conventional method carried out according to the procedure shown in FIG. 4 and the result thereof are shown. As an implementation procedure, the ink key opening degree control is first performed as a test machine in order to carry out under the same conditions as the embodiment of the present invention. A BT full-size BB offset web offset press made by Mitsubishi Heavy Industries was selected.

  In the prepared version, SCID was laid out in the pattern portion, and a single color 80% patch was laid out in the blank portion as shown in FIG. The desired color density was set to the ink key opening controller as [K C MY] = [1.00 0.95 0.90 0.85]. After the above preparation, printing was started. The course of going through all the steps was as follows.

0 min 00 sec Start of printing press, speed up, fixed at 500 rpm, ink on 1 min 00 sec. Ink key opening control device adjusts color density of patches arranged in width direction to desired color density Ink key opening control starts 2:00 pm The color density of patches arranged in the width direction changes at the desired color density However, the color density of the pattern part changes at a lower color density than the desired color density. As a result, the ink key Although the color density of the patches arranged in the width direction by the opening degree control device was controlled to a desired color density, the color density of the pattern portion was changed at a color density lower than the desired color density. The visual evaluation of the pattern was not good. Specifically, the color density was insufficient.

  The present invention can be used for offset printing, particularly preferably for offset rotary printing.

It is a composition schematic diagram showing an example of an offset rotary press of the present invention. It is a flowchart which shows an example of the control method using this invention. It is an example of the layout of a patch required when using the control method using this invention. It is a flowchart which shows an example of the control method using the conventional method. It is an example of the layout of a patch required when using the control method using the conventional method. It is a graph which shows the first color density distribution calculation result. It is a graph which shows the color density distribution calculation result of a stable state.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Printing unit 11 Black (K) unit 12 Indigo (C) unit 13 Red (M) unit 14 Yellow (Y) unit 15 Printing paper 20 Ink key opening control device 21 Arithmetic device 22 Measuring camera 23 Cable 61-68 Step 91 Printing paper 92 Patches arranged in the width direction 92K 80% patch of ink density of the corresponding pattern part 92C 80% patch of indigo density of the corresponding pattern part 92M 80% patch of red density of the corresponding pattern part 92Y Corresponding pattern 80% patch 93 of the yellow density of the part 93P patch arranged in the flow direction 93K 80% patch of the black density of the corresponding picture part 93C 80% patch of the indigo density of the corresponding picture part 93M 80 of the red density of the corresponding picture part % Patch 93Y 80% patch 94-101 of yellow density of the corresponding pattern part Pattern part 140-143 Tep 160 Printing paper 161 Patch arranged in the width direction 161K 80% patch of black density of corresponding pattern part 161C 80% patch of indigo density of corresponding pattern part 161M 80% patch of red density of corresponding pattern part 161Y Corresponding 80% patch 162-169 of yellow density of the pattern part to do

Claims (5)

In an ink key control method for controlling the opening of an ink key based on information obtained by measuring a patch provided on a printing paper surface,
A measurement stage for measuring the color density of the patches provided in the flow direction and width direction on the printing paper surface,
A prediction step of predicting the overall color density on the printing paper surface from the measurement result of the patch ;
A control floor for controlling the opening of the ink key based on the predicted color density on the printing paper surface,
An ink key control method.   The ink key control method according to claim 1, wherein the control step controls the average color density of the predicted color density on the printing paper surface to be a desired color density. In an ink key control device that controls the opening of an ink key based on information obtained by measuring a patch provided on a printing paper surface,
Measuring means for measuring the color density of patches provided in the flow direction and width direction on the surface of the printing paper;
Prediction means for predicting the overall color density on the printing paper surface from the measurement result of the patch ,
Control means for controlling the opening of the ink key based on the predicted color density on the printing paper surface,
Ink key control device.   4. The ink key control device according to claim 3, wherein the control means controls the predicted average color density on the printing paper surface to be a desired color density. An offset printing machine comprising the ink key control device according to claim 3.