JP4032853B2 - Ink / water control method and ink / water control device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an ink / water control method for controlling an ink supply device / water supply device in offset printing, and an apparatus using the same.
[0002]
[Prior art]
Conventionally, adjustment of ink supply amount and water supply amount in offset printing has been performed by an operator. As the adjustment method, the printed matter is appropriately extracted during printing, and the ink supply amount and the water supply amount are adjusted based on the experience of the operator so as to obtain a desired print quality while visually comparing the extracted printed matter and the proof. There was a way to make adjustments.
[0003]
The adjustment of ink supply and water supply by such an operator is a general work flow: “OK sheet creation”, in which color matching is performed from the start of printing and OK sheets are created by matching proofs with colors and tone. And “after OK sheet” for managing the print quality until the end of printing thereafter.
[0004]
Here, “OK sheet creation” is first considered. At the time of creating the OK sheet, the operator is required to create the OK sheet so that the desired print quality can be quickly obtained by matching the color and tone to the proof. However, it is difficult to adjust the ink supply amount and the water supply amount in a short time so as to obtain a desired print quality. This is because it is necessary to adjust the ink supply amount and the water supply amount so as to obtain a desired print quality while always balancing the ink supply amount and the water supply amount.
[0005]
The balance between ink supply and water supply greatly affects print quality. In other words, if the balance between the ink supply amount and the water supply amount is lost, the print quality is significantly reduced.
Specifically, when the water supply amount is excessive, the ink becomes over-emulsified and stable ink transfer is not performed. For this reason, the halftone dot reproducibility is deteriorated, resulting in variations in monochromatic tone. In addition, the trapping balance of the primary color and the secondary color is disturbed, causing variations in the colors to be combined. On the other hand, when the amount of water supply becomes too small, printing trouble such as scumming occurs.
[0006]
Next, consider after the OK sheet. After the OK sheet, the operator is required to maintain the printing quality of the OK sheet with high accuracy. However, when the color tone changes, it is difficult to determine whether it is due to the amount of ink or the amount of moisture. There is. The judgment requires high judgment by experienced operators, but the number of operators having such high judgment is decreasing year by year. In addition, since humans have a visual function of color adaptation in which the color of an object looks like a color unique to the object even if the color changes, there is a problem in terms of accuracy in visual evaluation by the operator. Therefore, there is a demand for a control device that performs color matching between “OK sheet creation” and “after OK sheet” instead of an operator.
[0007]
Due to the above background, in recent years, as a device that adjusts the ink supply amount and water supply amount during printing on behalf of the operator, data related to print quality from the color patches in the color bar on the printing paper is displayed on the printing press. Ink key control device to control the ink key opening and to measure the amount of ink and moisture at any detection point on the surface of the ink roller using infrared absorption, and the detected value and the pre-input target value or There has been proposed a water supply amount control device for comparing and calculating a preset target value at the detection point and controlling the water supply amount of the ink. The following three cases can be considered as cases where these apparatuses are actually used at the printing site. In the following, we will consider each of the three cases.
When the ink key control device is used alone. When the water supply amount control device is used alone. When both the ink key control device and the water supply amount control device are used independently.
First, consider the case where only the ink key control device is used. Since this ink key control device controls only the ink key so that the solid density in the color bar approaches the target density, it does not consider the balance between the ink supply amount and the water supply amount. For this reason, the solid density during printing is stabilized, but the balance of ink and water may be deteriorated. In this case, although the solid density value is a desired density, a desired print quality may not be obtained in a halftone. In addition, when the balance between the ink supply amount and the water supply amount is further deteriorated, problems such as printing troubles such as over-emulsification of ink and background stains have been pointed out.
[0009]
Next, consider the case where only the water supply amount control device is used. Since the water supply amount control device does not measure the color on the printing paper surface, it cannot be controlled while guaranteeing the final print quality. For this reason, although the balance between the ink supply amount and the water supply amount is stable, the desired print quality may not be obtained on the printing paper surface. Specifically, the density of the printed matter may be higher or lower than a desired density. Further, since the proper ink / water balance also changes when the ink amount changes, there is a problem in that it is difficult to control the water supply amount unless the printing machine is stable and the ink amount fluctuation is small.
[0010]
Finally, consider the case where both the ink key control device and the water supply amount control device are used independently. When the two devices are used independently, the ink key control device controls the ink supply amount so that the solid density in the color bar approaches the target density, and the water supply control device controls the ink amount and moisture on the ink roller. The amount of water supply is adjusted so that the ink / water balance is appropriate. Here, both the ink key control device and the water supply amount control device are based on the premise that the ink amount on the ink roller is stable. For this reason, there are cases where improper control is performed if control is performed while the ink amount on the ink roller is not stable, so the ink key control device and water supply control device cooperate with each other using their respective data. It is necessary to perform control that takes In particular, when both the ink key control and the water supply amount control are performed independently at the time of printing, the ink amount is drastically changed by the ink key control device. As a result, the ink is excessively emulsified or the water supply amount is too low. It has been a problem that printing troubles such as background smudges occur.
[Problems to be solved by the invention]
[0011]
The present invention has been made in view of the problems of the prior art, and solves the problems that have occurred when the control of the ink supply amount and the water supply amount are performed separately or both independently. It is an object of the present invention to provide an ink / water control method and an ink / water control apparatus that can perform ink / water control in order to obtain a highly accurate printed matter, and an offset printing machine equipped with them.
[0012]
[Means for Solving the Problems]
To achieve the above object, the first invention of the present invention, the Lee Nki supply apparatus for determining an optimum ink supply quantity of the ink control value calculated from the difference between the patch density value and the target density value based on An ink / water control method for an offset printing press that controls a water supply device that determines an optimal water supply amount based on a water control value calculated from a difference between an ink / water balance value and a target ink / water balance value Because
At the time of printing, when the difference between the patch measurement value obtained by measuring the patch density on the printing paper surface and the target value is not within the allowable range, an ink control value based on the difference is calculated, and the ink control Controlling the ink supply device based on the value, calculating a water control value corresponding to the ink control, controlling the water supply device based on the water control value,
In the control of the ink supply device after the OK sheet, when the variation of the ink / water measurement value is within the allowable range, the ink control is performed according to the difference between the patch measurement value and the target value,
In the control of the water supply device after the OK sheet, when the variation of the patch measurement value is within an allowable range, water control is performed according to the difference between the ink / water amount measurement value and the target value. This is a characteristic ink / water control method.
[0016]
Further, the second invention of the present invention is an ink / water amount measuring means for measuring an ink / water amount on an ink roller of a printing unit, and a patch measuring means for measuring a color patch in a color bar printed on a printing paper surface. When, as input inking water measurement and patch measurement values obtained from the respective measuring means, the ink control value of the ink supply device and the water supply device by the ink-water control method according to claim 1, wherein the water control value The ink / water control device is provided with an arithmetic device for outputting the ink.
[0017]
According to a third aspect of the present invention, there is provided an offset printing machine comprising the ink / water control device according to the second aspect.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
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 is not limited to the following content.
[0019]
The ink / water control device of the present invention uses the ink amount / water amount on the metal ink rollers (17) of the upper and lower cylinders of the printing units (10, 11, 12, 13) to the ink / water amount measuring sensor (20). To obtain the ink / water measurement (22).
[0020]
Moreover, the color patch in the color bar printed on the paper surface of the printed matter printed through each printing unit (10, 11, 12, 13) is measured by the color measurement sensor or the density measurement sensor (21). Thus, the colorimetric value or density value (23) of the printed matter is obtained. Various patches can be used as the color patch. In the following explanation, the most commonly used solid patch will be used. Colorimetric values or density values can be used as data measured from the color bar by the color measuring sensor or density sensor. However, when controlling the ink supply amount, it is easier and more reliable to use the density value. Since the supply amount can be controlled, the concentration values are used in the description and examples of the present invention.
[0021]
The ink / water quantity measurement value (22) and the density value (23) obtained as described above are sent to the arithmetic unit (25). The same processing may be used for printing and printing after the OK sheet, but the printing response such as scumming is avoided at printing speed, and the printing is the same as the OK sheet after printing. Since it is most demanded to control the quality, it is more ideal to perform separate processing at the time of printing and after the OK sheet.
[0022]
In the arithmetic unit (25), arithmetic processing for ink control and arithmetic processing for water control are performed in parallel.
[0023]
Next, the flow of processing for ink control at the time of printing will be described with reference to FIG. First, the density of the solid patch in the color bar is measured (Step 1), and the obtained solid density value is compared with the target value input in advance (Step 2), and the difference between the solid density value and the target value is calculated. A solid density check is performed to determine whether or not is within the allowable range.
[0024]
Here, if the difference between the solid density value and the target value is within the allowable range as a result of the solid density check, the solid density value newly obtained by the measurement is used to repeat the solid density check, that is, step 1. 2 is performed.
[0025]
If the difference between the solid density value and the target value is not within the allowable range as a result of the solid density check, the ink control is performed from the difference between the calculated solid density value and the target value during the solid density check (steps 1 and 2). A value is calculated (step 3), the ink key opening is adjusted using the data, and ink control (step 4) is performed so that the optimum ink supply amount is obtained.
[0026]
At this time, an optimal water control value is calculated based on the ink control value (step 5), and the water control is performed using the value to adjust the water roller rotation speed so as to obtain an optimal water supply amount (step 6). )I do. The water control value is controlled with a raising width corresponding to the ink control value. As a result, water control corresponding to ink control can be performed quickly, and printing troubles such as background smearing can be avoided even if abrupt ink control is performed.
[0027]
Next, the flow of processing for ink control after the OK sheet will be described with reference to FIG. First, the density of the solid patch in the color bar is measured (step 101), the obtained solid density value is compared with the target value input in advance (step 102), and the difference between the solid density value and the target value is calculated. A solid density check is performed to determine whether or not is within the allowable range.
[0028]
Here, if the difference between the solid density value and the target value is within the allowable range as a result of the solid density check, the solid density value newly obtained by measurement is used to repeat the solid density check, that is, step 101, 102.
[0029]
If the difference between the solid density value and the target value is not within the allowable range as a result of the solid density check, then the ink fluctuation amount is stable using the measured ink and water amount obtained from the ink roller. Ink amount stability check is performed (steps 103 and 104). At this time, instead of the ink fluctuation amount, the water fluctuation amount or a ratio thereof may be used.
[0030]
Here, as a result of the ink amount stability check, if the ink fluctuation amount is not within the allowable range within a certain time, the ink fluctuation amount is stabilized by using the newly measured ink / water amount measurement value. Check the ink amount stability repeatedly until
[0031]
As a result of the ink amount stability check, if the variation amount of the ink is within the allowable range within a certain time, the solid patch density measurement is performed again (step 105), and the obtained solid density value and the target inputted in advance are measured. A comparison operation with a value (step 106) is performed, and a solid density check is performed to determine whether the difference between the solid density value and the target value is within an allowable range. If the difference between the solid density value and the target value is within the allowable range, the process returns to step 101 and the solid density check is repeated.
Here, if the difference between the solid density value and the target value is not within the allowable range, the ink control value is calculated from the difference between the latest solid density value and the target value (step 107), and the ink key opening degree is used using the calculated value. Is adjusted to perform an ink control (step 108) so that an optimum ink supply amount is obtained.
[0032]
Next, the flow of processing for water control will be described with reference to FIG. First, the ink / water amount on the ink roller is measured (step 201), and the ink / water balance value calculated from the obtained ink / water amount measurement value is compared with the target value inputted in advance (step 202). ) Check the ink / water balance to see if the difference between the ink / water balance and the target value is within the allowable range.
[0033]
At this time, if the difference between the ink / water balance value and the target value is within the allowable range as a result of the ink / water balance check, the ink / water amount measurement value newly obtained by the measurement is used to repeat the ink. -A water balance check (steps 201 and 202) is performed.
[0034]
If the difference between the ink / water balance value and the target value is not within the allowable range as a result of the ink / water balance check, then the solid density value obtained from the solid patch in the color bar will be solid. A density stability check (steps 203 and 204) is performed.
[0035]
At this time, as a result of the solid density stability check, if the fluctuation amount of the solid density value within a certain time is not within the allowable range, the solid density value is stabilized by using the solid density value newly obtained by measurement. Repeat until the solid density stability check.
[0036]
As a result of the solid density stability check, if the fluctuation amount of the solid density value within a certain time is within the allowable range, the ink / water quantity on the ink roller is measured again (step 205), and the resulting ink / water quantity measurement is performed. The ink / water balance value calculated from the value is compared with the target value inputted in advance (step 206), and the ink indicating whether or not the difference between the ink / water balance value and the target value is within the allowable range.・ Check water balance. If the difference between the ink / water balance value and the target value is within an allowable range, the process returns to step 201 to repeat the ink / water balance check. If the difference between the ink / water balance value and the target value is not within the allowable range, the water control value is calculated from the difference between the latest ink / water balance value and the target value input in advance (step 207). Then, the water source roller rotation speed is adjusted using the value (step 208), and water control is performed so that the optimum water supply amount is obtained.
[0037]
As described above, after the OK sheet, when operating the ink supply device, it is confirmed that the ink / water amount measurement value does not fluctuate, and when operating the water supply device, the patch measurement value fluctuates. By confirming that there is no ink, the ink control and the water control can be performed so that the optimum ink amount and water amount are supplied. Further, when the ink amount is not stable for a certain period of time and both ink control and water control cannot be performed, it is possible to determine an abnormal state and notify the operator by an alarm.
[0038]
<Example>
Here, the control device of the offset printing press of the present invention was installed in an offset rotary press manufactured by Mitsubishi Heavy Industries, Ltd., and ink / water control from printing printing was performed using this control device.
[0039]
First, before starting printing, black 1.7, indigo 1.5, red 1.5, yellow 1.2 as reference density values and 20% black, 18% indigo, red are used as reference dot gain values. 18% and 18% of yellow as reference ink / water balance values are input to the ink / water control device of the present invention in advance so as not to cause scumming from the past history data. The dot gain value and the reference ink / water balance value are set as the target density value, the target dot gain value, and the target ink / water balance value, respectively, and the target density value of each color is ± 0.15, and the target ink / water balance value is set. On the other hand, an allowable value of + 5% was set, and ink / water control was performed from the start of printing using an ink / water control device. Under the present circumstances, the printed matter was extracted every 100 sheets from printing as an evaluation sample, and visual evaluation of the extracted printed matter was performed.
[0040]
As a result, a desired printed matter was obtained with about 1000 sheets from the start of printing. When the density value of this printed matter was measured, black 1.65, indigo 1.5, red 1.45, yellow 1.15, dot gain values were black 20%, indigo 17%, red 16%, yellow 16%. From these data, it was confirmed that the balance between the printing density and the halftone was good.
[0041]
At this stage, the ink / water control using the ink / water control apparatus according to the present invention was once released, and the operator finely adjusted the ink key according to the color sample, and the OK sheet was output. At this time, since the balance between the printing density and the halftone was already good, the number of printed sheets required for the operator to create the OK sheet was 500 sheets.
[0042]
Then, the ink / water control device was used again for control based on the density of the OK sheet and the ink / water balance at that time. Again, up to 20000 printed materials were extracted every 100 sheets after the OK sheet as an evaluation sample, and visual evaluation of the extracted printed materials was performed.
[0043]
As a result, the printed matter after the OK sheet was very good with almost no color tone fluctuations. The average color difference between the extracted printed material and the OK sheet is ΔE = 2.5, which is ΔE = 3 or less, which is a general standard for color difference, and the effect was recognized not only by visual evaluation but also by colorimetric data. .
[0044]
<Comparative example>
Here, as a comparative example, a conventional ink control device that controls the ink supply amount using only the color data of the printed matter is installed in an offset rotary press manufactured by Mitsubishi Heavy Industries, Ltd., and printing is performed in the same manner as in Example 1 using this. Ink control was performed during printing.
[0045]
First, before starting printing, black 1.7, indigo 1.5, red 1.5, yellow 1.2 as reference density values and 20% black, 18% indigo, red are used as reference dot gain values. 18% and 18% of yellow are input to the ink control apparatus, and the reference density value and the reference dot gain value are set as the target density value and the target dot gain value, respectively, and ± 0.15 for the target density value of each color. When the control was performed from the printing start using the ink control device, the printed material was extracted every 100 sheets from the printing, and the extracted printed material was visually evaluated.
[0046]
As a result, immediately after printing, the ink supply amount was suddenly increased under the control of the ink control device, so that the water supply amount was insufficient at a portion where there was a lot of patterns, resulting in scumming. Immediately, the operator adjusted the number of rotations of the water source roller, and almost 3000 printed sheets were obtained. However, in some parts with few pictures, it was flat, with no gloss and low contrast.
[0047]
In order to quantitatively grasp the above-mentioned gloss and contrast defects, the density values of this printed matter were measured. As a result, black 1.60, indigo 1.45, red 1.39, yellow 1.08 and Example 1 were obtained. Although close, the dot gain values were 15% black, 10% indigo, 15% red, and 16% yellow. When observing the halftone dot with a loupe, a poor transfer occurred due to a poor balance between ink and water, and the halftone dot reproducibility was remarkably deteriorated. Probably due to ink emulsification due to excessive water supply.
[0048]
The above content is an example of a case where a desired color tone cannot be obtained in some halftones because the balance of ink and water cannot be controlled by the conventional method that manages the color tone from only the color data.
[0049]
After that, the ink control by the ink control device is canceled once in the same manner as in Example 1, and the operator adjusts the ink key and water based on the color sample to create an appropriate ink amount and ink / water balance to create an OK sheet. However, it required about 5000 sheets to be printed. Using the OK sheet as a reference, the ink control device was used again to continue control. Here, in the same manner as in Example 1, up to 20000 printed materials were extracted every 100 sheets after the OK sheet as an evaluation sample, and visual evaluation of the extracted printed materials was performed.
[0050]
As a result, color variation was observed in part of the pattern. The average color difference between these extracted prints and the OK sheet is ΔE = 3.8, which is slightly larger than ΔE = 3, and the change in the trapping rate is confirmed from the colorimetric data of the secondary color, and there is an obstacle due to the ink / water balance. Was recognized. This may be because the ink / water balance has been lost.
[0051]
【The invention's effect】
As is clear from the above description, the ink / water control device of the present invention is a patch measurement value related to the print quality obtained by measuring the color patch in the color bar printed on the paper surface of the printed matter, and the ink. Since the ink supply amount and the water supply amount obtained by measuring the ink amount of the ink present on the roller and the water amount contained in the ink are related to each other, the ink supply amount and the water supply amount are controlled to the optimum values. Ink / water control can be performed. Furthermore, according to the ink / water control device of the present invention, it is possible to expect effects such as eradication of printing defects such as background stains and improvement of productivity by shortening the color matching time.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram of an offset printing machine equipped with an ink / water control device of the present invention.
FIG. 2 is an explanatory diagram of a processing flow of ink / water control of the present invention at the time of printing.
FIG. 3 is an explanatory diagram of a processing flow of ink / water control of the present invention after an OK sheet.
FIG. 4 is an explanatory diagram of a processing flow of water control of the present invention after an OK sheet.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 1st printing unit 11 2nd printing unit 12 3rd printing unit 13 4th printing unit 15 Plate cylinder 16 Blanket cylinder 17 Metal ink roller 18 Printing paper 20 Ink / water measurement sensor 21 Color measurement sensor or density measurement sensor 22 Ink / Measured water amount 23 Colorimetric value or density value 25 Arithmetic unit 26 Ink control value 27 Water control value

Claims (3)

Calculated from the difference between b Nki feeder and, ink water balance value and the target ink water balance values to determine the optimum ink supply quantity based on the calculated ink control value from the difference between the patch density value and the target density value An ink / water control method for an offset printing machine for controlling a water supply device that determines an optimal water supply amount based on the water control value ,
At the time of printing, when the difference between the patch measurement value obtained by measuring the patch density on the printing paper surface and the target value is not within the allowable range, an ink control value based on the difference is calculated, and the ink control Controlling the ink supply device based on the value, calculating a water control value corresponding to the ink control, controlling the water supply device based on the water control value,
In the control of the ink supply device after the OK sheet, when the variation of the ink / water measurement value is within the allowable range, the ink control is performed according to the difference between the patch measurement value and the target value,
In the control of the water supply device after the OK sheet, when the variation of the patch measurement value is within an allowable range, water control is performed according to the difference between the ink / water amount measurement value and the target value. Characteristic ink / water control method. Ink / water amount measuring means for measuring the amount of ink / water on the ink roller of the printing unit, patch measuring means for measuring the color patches in the color bar printed on the printing paper, and inks obtained from the respective measuring means as input the amount of water measured value and the patch measurement value, and characterized in that it comprises an arithmetic unit for outputting the ink control value and the water control value of the ink supply device and the water supply device by the ink-water control method according to claim 1, wherein Ink / water control device. An offset printing machine comprising the ink / water control device according to claim 2 .

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