JP4365816B2 - Printing machine and ink supply method for printing machine - Google Patents

Description

  The present invention relates to a printing machine that adjusts the color tone of a printing sheet by adjusting an ink supply amount, and an ink supply method for a printing machine that corrects the ink supply amount in accordance with the lateral flow of ink.

  In a printing press such as a sheet-fed printing press or a rotary printing press, the ink supplied from the ink fountain to the printing cylinder by adjusting the amount of gap (referred to as ink key opening) between the ink key and the ink source roller provided in the ink supply device. The supply amount is adjusted. A plurality of ink keys are arranged in parallel in the printing width direction, and the ink key opening degree is adjusted by independently swinging each ink key, so that each ink key width unit (referred to as ink supply zone or key zone) The supply amount can be adjusted.

The ink supply amount is larger as the line rate of the printed pattern is larger, and is smaller as the line rate of the printed pattern is smaller, and needs to be set according to each line rate of the printed pattern.
Conventionally, the adjustment of the ink key opening in a printing machine may be performed while referring to the density of the printed sheet manually printed by the operator, but an ink supply amount automatic setting device that automatically sets the ink key opening has also been proposed. (See Patent Document 1).

In the technique of Patent Document 1, an actual color mixture halftone density for each key zone of a print sheet is measured by a line sensor type IRGB densitometer provided on the travel line of the print sheet, and the measurement result of the actual color mixture halftone density is obtained. Based on this, the actual monochromatic halftone density of each ink color is detected, and feedback control is performed so that the opening degree of the ink key corresponding to each key zone is adjusted so that the actual monochromatic halftone density becomes the target monochromatic halftone density.
JP 2004-106523 A

However, in the color tone control of a conventional printing press such as the technique of Patent Document 1 as described above, the ink key opening is reduced to the limit (that is, ink is supplied) by feedback control, particularly in a key zone having a low image area ratio. Even when the ink key opening degree 0) disappears, the actual monochromatic halftone density may become larger than the target monochromatic halftone density due to excessive supply of ink.
FIG. 13 is a schematic perspective view showing a configuration relating to ink supply from an ink supply device to a plate cylinder in a conventional printing press. As shown in FIG. 13, in an ink supply device of a conventional printing press, ink is supplied from an ink fountain when ink is supplied from an ink fountain formed by an ink key 107, an ink base roller 106, and a side wall to the plate cylinder 4. The ink is appropriately kneaded while passing from the peripheral surface of the ink base roller 106 to each peripheral surface of the ink kneading roller group 110, and is supplied to the plate cylinder 103 by the ink form roller via the ink swing roller 111. .

  The ink swinging roller 111 rotates about the rotation axis, but simultaneously swings in the axial direction (printing width direction). As the ink oscillating roller 111 swings, the ink is further kneaded and the ink supply amount is different for each key zone, so that the ink film thickness rapidly decreases or increases at the boundary line between adjacent key zones. This prevents inconveniences such as the color tone of the printing sheet 8 changing extremely at the boundary line.

  However, when there is a high-drawing-rate key zone near the low-drawing-rate key zone, a large amount of ink is supplied to the high-drawing-rate key zone by the oscillation of the ink rocking roller 111 in the printing width direction. Ink flows laterally to the key zone having a low image-ratio, and a larger amount of ink is supplied than the amount of ink that should originally be supplied to the key zone having a low image-ratio. This is the cause of inconvenience (this is called ink cross-flow).

In this way, if ink is supplied excessively to the key zone with a low image area ratio, not only will the density of the pattern become too high, but the ink will remain in the key zone with a low image area ratio, resulting in a non-image area. In any case, the print sheet becomes waste paper.
In such a case, the operator visually and manually reduces the amount of ink supplied to the key zone having a high image area ratio to reduce the amount of ink supplied to the key zone having a low image area ratio. The accuracy varies depending on the skill level of the operator.For example, if the amount of ink supplied to the high image area is too small, the color of the high image area will become lighter, and each color ink will be adjusted in a balanced manner. If this is not done, the color balance will be disturbed, and this will also cause waste paper.

  The present invention was devised in view of such problems, and when ink lateral flow occurs due to the presence of a high image area ratio key zone, the ink lateral flow correction is performed to apply an appropriate amount of ink to each key zone. It is an object of the present invention to provide a printer and an ink supply method for a printer that can supply the printer.

  In order to achieve the above-mentioned object, the printing machine of the present invention according to claim 1 is an ink supply device that supplies ink to each ink supply zone divided in the printing width direction at the time of printing; Ink supply amount control comprising target value setting means for setting a target value of the ink supply amount for each ink supply zone, and controlling the ink supply device so that the ink supply amount of each ink supply zone becomes the target value The ink supply amount control means, the ink supply amount control means for acquiring the image drawing rate of the printed pattern of each ink supply zone, and the ink supply amount of any one of the ink supply zones. When the target value reaches the lower limit value and the ink density of the printed sheet exceeds the allowable range, the image line of each ink supply zone acquired by the image line rate acquisition unit Correction means for selecting a high-line-rate zone having a higher image-line ratio than a preset image-line-rate threshold, and reducing and correcting the target value of the high-image-area ratio zone by a predetermined correction amount. It is characterized by that.

According to a second aspect of the present invention, there is provided the printing press according to the first aspect of the present invention, wherein only one of the image area ratio threshold values is set, and the ink supply zone has an image area ratio higher than the image area ratio threshold value. All are characterized by being selected as the high image area ratio zone.
According to a third aspect of the present invention, there is provided the printing machine according to the first aspect, wherein only one of the image line ratio threshold values is set, and an ink supply zone having a image line ratio higher than the image line ratio threshold value is provided. When there are a plurality of inks, the ink supply zone having the highest image drawing rate is selected as the high image drawing rate zone.

  According to a fourth aspect of the present invention, there is provided the printing machine according to the first aspect, wherein the image line ratio threshold value is smaller as the ink supply zone is closer to the ink supply zone where the target value has reached the lower limit value or less. All of the ink supply zones having a higher image area ratio than the corresponding image area ratio threshold value are selected as the high image area ratio zones.

  According to a fifth aspect of the present invention, there is provided a printing machine according to the present invention, wherein an ink supply device that supplies ink for each ink supply zone divided in the printing width direction during printing, and an ink supply for each ink supply zone based on a printing result. A target value setting means for setting a target value for the amount; and an ink supply amount control means for controlling the ink supply device so that the ink supply amount in each ink supply zone becomes the target value. The supply amount control means includes a line rate acquisition means for acquiring a line rate of a printed pattern in each ink supply zone, and a target value of the ink supply amount in any one of the ink supply zones reaches a lower limit value. In addition, when the ink density of the printed sheet exceeds the allowable range, the image line ratio acquisition unit performs the ink supply zone adjacent to the one ink supply zone. It is determined whether or not the acquired image line ratio of each of the ink supply zones is a high image area rate zone whose image area ratio is higher than a preset image area rate threshold, and the adjacent ink supply zone is If it is a high image area ratio zone, it is characterized in that it comprises correction means for reducing and correcting the target value of the adjacent ink supply zone by a predetermined correction amount.

  A printing machine according to a sixth aspect of the present invention is the printing machine according to any one of the first to fifth aspects, wherein the printing machine is a multi-color offset printing machine, the ink supply device and the ink supply. An amount control unit is provided for each ink color printing device, and the correction unit of the ink supply amount control unit for any one of the ink colors reduces the target value of the high image area ratio zone by the correction amount. In the case of correction, the correction means for each of the other ink colors also corrects the target value of the ink supply zone corresponding to the high image area ratio zone according to the correction amount.

The printing press of the present invention according to claim 7 is the printer according to any one of claims 1 to 6, wherein the predetermined correction amount is a value having the target value as an allowable lower limit value. It is a feature.
Moreover, the printing press of the present invention according to claim 8 is the one according to any one of claims 1 to 7, wherein the ink supply device includes a plurality of ink keys installed in parallel in the printing width direction, At the time of printing, ink is supplied to each ink supply zone divided for each ink key, and the ink supply amount control means sets a target color mixture halftone density setting for setting a target color mixture halftone density of a printed pattern for each ink supply zone. Means, an IRGB densitometer disposed on a running line of the print sheet obtained by printing, and an actual RGB color density measured for each ink supply zone of the print sheet by operating the IRGB densitometer. A target halftone dot density measuring unit, and a target halftone dot area ratio for each ink color corresponding to the target mixed color halftone density based on a correspondence relationship between a predetermined halftone dot area ratio and a mixed color halftone density. An area ratio calculating means; and an actual halftone dot area ratio calculating means for obtaining an actual halftone dot area ratio of each ink color corresponding to the actual mixed color halftone density based on the correspondence relationship between the halftone dot area ratio and the mixed color halftone density. A target monochromatic halftone density calculating means for obtaining a target monochromatic halftone density corresponding to the target halftone dot area ratio based on a correspondence relationship between a predetermined halftone dot area ratio and the monochromatic halftone density, and the halftone dot area ratio and the single color Based on the correspondence with halftone density, the real monochrome halftone density calculating means for obtaining the actual monochrome halftone density corresponding to the actual halftone dot area ratio, and the correspondence between the preset halftone dot area ratio, monochrome halftone density, and solid density A solid density deviation calculating means for obtaining a solid density deviation corresponding to a deviation between the target monochrome halftone density and the actual monochrome halftone density based on the target halftone dot area ratio, and setting the target value The means provides the ink supply based on the solid density deviation. It is characterized by setting a target value of the quantity.

  Further, the printing press of the present invention according to claim 9 is the printer according to claim 8, wherein the solid density deviation obtained by the solid density deviation calculating means is compared with a predetermined criterion value. Printing density determination means for determining whether or not the ink density is within a preset allowable range, and whether or not the ink density exceeds the allowable range is determined by the printing density determination means It is characterized by performing based on the results.

  Further, in the printing machine of the present invention according to claim 10, in the ink supply according to any one of claims 1 to 7, whether or not the ink density of the printing sheet is within a preset allowable range. Print density determination means for determining each zone is provided, and whether or not the ink density exceeds an allowable range is determined based on a determination result of the print density determination means.

  An ink supply method for a printing press according to the present invention described in claim 11 is provided in the printing press, and in an ink supply device that supplies ink for each ink supply zone divided in the printing width direction at the time of printing. An ink supply amount control method that sets a target value of an ink supply amount for each ink supply zone based on the ink supply zone and controls the ink supply device so that the ink supply amount of each ink supply zone becomes the target value. In any one of the ink supply zones, the target value of the ink supply amount has reached the lower limit (0). And a correction condition determination step for determining whether or not a correction condition that the ink density of the printed sheet exceeds the allowable range is satisfied, and the correction condition determination step. If it is determined that the correction condition is satisfied, the image line rate of each ink supply zone acquired by the image line rate acquisition step is smaller than the image line rate threshold set in advance. And a correction step of selecting a high-image-ratio zone with a high and reducing the target value of the high-image-ratio zone by a predetermined correction amount.

  According to a twelfth aspect of the present invention, there is provided an ink supply method for a printing press according to the present invention, wherein an ink supply device that is provided in a printing press and supplies ink for each ink supply zone divided in the printing width direction at the time of printing. An ink supply amount control method that sets a target value of an ink supply amount for each ink supply zone based on the ink supply zone and controls the ink supply device so that the ink supply amount of each ink supply zone becomes the target value. In any one of the ink supply zones, the target value of the ink supply amount has reached the lower limit (0). And a correction condition determination step for determining whether or not a correction condition that the ink density of the printed sheet exceeds the allowable range is satisfied, and the correction condition determination step. The ink supply zone adjacent to the one ink supply zone is determined from the line rate of each ink supply zone acquired by the image rate acquisition means. It is determined whether the image area ratio is a high image area ratio that is higher than the image area ratio threshold value set in advance, and if the adjacent ink supply zone is the high image area ratio zone, the adjacent ink supply is determined. And a correction step for reducing and correcting the target value of the zone by a predetermined correction amount.

According to a thirteenth aspect of the present invention, there is provided a printer according to the present invention, wherein an ink supply device that supplies ink for each ink supply zone divided in the printing width direction and a target value for the ink supply amount are set for each ink supply zone. A target value setting means; and an ink supply amount control means for controlling the ink supply device in accordance with the target value, wherein the ink supply amount control means includes the ink supply zone in one of the ink supply zones. when the target value of the ink supply amount is equal to or less than a predetermined lower limit value, it is characterized by reducing the target value of the ink supply amount of the other ink feed zone of the ink supply zone of the 1.

  Therefore, according to the printing machine of the present invention described in claim 1 and the ink supply method of the printing machine described in claim 11, although the target value of the ink supply amount is the lower limit, Even if there is an ink supply zone in which the ink density exceeds the allowable range, a high image area ratio with a image area ratio higher than a preset image area ratio threshold is selected, and the high image area ratio zone is selected. Since the target value is corrected to decrease by a predetermined correction amount, it is possible to reduce the amount of ink that is excessively supplied from the high image area zone due to the lateral flow of the ink, and to prevent the ink density from exceeding the allowable range. Can do.

  According to the printing machine of the present invention described in claim 2, in addition to the effect of claim 1, all the ink supply zones in which only one image area ratio threshold is set and the image area ratio is higher than the image area ratio threshold are set. Is selected as the high-drawing-rate zone, so the control for selecting the high-drawing-rate zone is simple, and all the high-drawing-rate zones that are considered to be the cause of ink lateral flow are corrected to decrease the ink supply amount. It is possible to reduce the amount of ink that is excessively supplied from the rate zone due to the lateral flow of the ink, and it is possible to prevent the ink density from becoming larger than the allowable range.

  According to the third aspect of the present invention, in addition to the effect of the first aspect, only one image area threshold is set, and an ink supply zone having an image area higher than the image area threshold is provided. If there are multiple inks, the ink supply zone with the highest line drawing rate is selected as the high image drawing rate zone. It is possible to reduce the amount of ink that is excessively supplied from the zone due to the lateral flow of ink, and it is possible to prevent the ink density from becoming larger than the allowable range. Further, since there is only one ink supply zone for reducing the ink supply amount, it is possible to suppress the color tone disturbance caused by reducing the ink supply amount to the minimum range.

According to the printing machine of the present invention described in claim 4, in addition to the effect of claim 1, the image line ratio threshold is an ink supply zone in which the target value of the ink supply amount has reached the lower limit value or less. Since the closer the ink supply zone is, the smaller the value is set, the ink lateral flow correction can be surely performed for the adjacent ink supply zone where the influence of the ink lateral flow is large.
Further, according to the printing machine of the present invention as set forth in claim 5 and the ink supply method of the printing machine as set forth in claim 12, the printing sheet is caused by the lateral flow of the ink even though the target value of the ink supply amount is the lower limit. Even when there is one ink supply zone in which the ink density exceeds the allowable range, the image drawing rate is higher than the image drawing rate threshold set in advance for the ink supply zone adjacent to the one ink supply zone. Since the image area ratio zone is selected and the target value of the high image area zone is reduced and corrected by a predetermined correction amount, it is possible to reduce the ink that is excessively supplied from the high image area zone by the lateral flow of ink. The ink density can be prevented from becoming deeper than the allowable range.

According to the printing machine of the present invention described in claim 6, in addition to the effects of claims 1 to 5, in the multi-color offset printing machine, when performing the lateral flow correction for specific ink, the printing sheet Disturbance of the upper color tone can be suppressed.
According to the printing machine of the present invention described in claim 7, in addition to the effects of claims 1 to 6, the correction amount with respect to the ink supply amount in the high image area ratio is set to the target lower limit value of the ink supply amount. Therefore, when ink lateral flow correction is performed, it is possible to suppress a decrease in ink density in the high image area ratio zone within an allowable range.

  According to the printing machine of the present invention described in claim 8, in addition to the effects of claims 1 to 7, each ink color in the printed pattern is based on the correspondence between the streak rate of each ink color and the mixed color halftone density. By obtaining the mixed color halftone density corresponding to the image line rate for each ink supply zone, and setting the mixed color halftone density corresponding to the image line rate as the target mixed color halftone density, color control can be performed immediately after the start of printing, It is possible to shorten the time until a desired color tone is obtained on the printed sheet, and to reduce the waste paper.

Further, according to the printing press of the present invention described in claim 9, in addition to the effect of claim 8, the ink density determination means compares the solid density deviation with a preset determination reference value on the print sheet. It is possible to reliably determine whether or not the ink density is within the preset allowable range.
According to the printing machine of the present invention described in claim 10, in addition to the effects of claims 1-7, whether or not the ink density of the printing sheet is within a preset allowable range is determined by the printing density determination means. The determination can be made reliably for each ink supply zone.

According to the printing machine of the present invention described in claim 13, when the target value of the ink supply amount in one ink supply zone is equal to or less than the predetermined lower limit value, the ink is transferred from the high image area zone by the lateral flow of ink. it is considered that it is excessively supplied, this time, because it reduces the target value of the other of the ink supply zone, it is possible to reduce the ink is excessively supplied by the ink transverse flow from the high image area ratio zone The ink density can be prevented from becoming larger than the allowable range.

Hereinafter, embodiments of the present invention will be described with reference to FIGS.
FIG. 1 is a flowchart for explaining ink lateral flow correction in ink supply amount control, FIG. 2 is a schematic side view showing a schematic configuration of a printing machine of the present invention, and FIG. 3 is for ink supply from an ink supply device to a plate cylinder. A schematic side view showing such a configuration, FIGS. 4 and 5 are all schematic diagrams showing a configuration of an ink supply device of a printing press, and FIG. 6 is a block diagram showing a functional configuration of a control system related to ink supply amount control. FIG. 7 is a block diagram showing a functional configuration of a control system for ink lateral flow correction in ink supply amount control.

  A schematic configuration of a printing press including an ink supply device according to the present embodiment will be described. FIG. 2 is a diagram showing a schematic configuration of an offset rotary press as a printing press provided with an ink supply device as one embodiment of the present invention. The offset rotary press in the present embodiment is a multicolor double-sided printing press, and ink colors [black (k), indigo (c), red (m), yellow (y)] along the conveyance path of the printing sheet 8. Printing units 2a, 2b, 2c, and 2d are installed for each. Each of the printing units 2a, 2b, 2c, and 2d is provided with an ink supply device 5 including an ink key 7 and an ink source roller 8. A control device 20 such as a computer is connected to each ink supply device 5, and the control device 20 adjusts the gap amount (that is, the ink key opening) of the ink key 7 with respect to the ink base roller 8. The ink supply amount in the apparatus 5 can be adjusted. Details of the functional configuration of the control device 20 as ink key supply amount control will be described later.

As shown in FIG. 3, an ink key opening adjusting device 50 that adjusts a gap between the ink key 7 and the ink base roller 6 by swinging each ink key 7 is provided below the ink key 7. Is electrically connected to the ink key opening adjusting device 50, and the ink key opening can be controlled by controlling the operation of the ink key opening adjusting device 50.
The supply amount is controlled by the control means 20 and the ink supplied from the peripheral surface of the ink base roller 6 is appropriately kneaded while passing through the peripheral surface of the ink roller group 11. After the extreme change in ink film thickness with respect to the ink film thickness at the boundary of each key zone is alleviated, the ink is supplied to the plate surface of the plate cylinder 4 via the ink form roller 13, and the ink adhering to the plate surface passes through the blanket cylinder 3. The image is transferred to the print sheet 8 as a pattern. Although not shown, since the offset rotary press of this embodiment is a double-sided printing, each printing unit 2a, 2b, 2c, 2d is provided with a pair of blanket cylinders 3 so as to sandwich the conveyance path of the printing sheet 8. A plate cylinder 4 and an ink supply device 5 are provided for each blanket cylinder 3.

  Further, a line sensor type IRGB densitometer (ink sensor) 1 is provided further downstream of the most downstream printing unit 2d. The IRGB densitometer 1 is a measuring instrument that measures the reflected light of the ink transferred onto the printing sheet 8 as the reflection density of I (infrared light), R (red), G (green), and B (blue). It is also possible to measure the mixed color halftone density of the entire width of the print sheet 8 or to measure the mixed color halftone density at an arbitrary position. Since the offset rotary press prints on both sides, the IRGB densitometer 1 is arranged on both the front and back sides so as to sandwich the conveyance path of the print sheet, and the reflection density on both the front and back sides can be measured.

  Next, the configuration of the ink supply device 5 will be described with reference to FIGS. 4 and 5. As shown in FIG. 4, the ink supply device 5 includes an ink source roller 6, an ink key 7, and an ink transfer roller 9. Ink stored in an ink fountain formed from the peripheral surface of the ink source roller 6 and the ink key 7 and the side plates 10a and 10b is passed through the gap between the ink key 7 and the peripheral surface of the ink source roller 6 A peripheral surface is supplied to an ink kneading roller group via an ink transfer roller 9.

  As shown in FIG. 5, a plurality of ink keys 7a to 7h are arranged side by side in the printing width direction. Adjacent ink keys 7a to 7h and ink keys 7a and 7h at the end and side plates 10a and 10b are in sliding contact with each other. Further, as shown in FIG. 3, the ink keys 7 a to 7 h can swing independently about the fulcrum shaft 51, and the gaps between the ink keys 7 a to 7 h and the peripheral surface of the ink source roller 6. (Ink key opening) can be adjusted. An ink key opening degree adjusting device 50 is provided below the ink keys 7a to 7h.

  The ink key opening adjusting device 50 includes a push-up metal 55 that contacts the lower surface of the front end of each ink key 7a to 7h, a pusher 56 that contacts the front end of the press-up metal 55 and expands and contracts the push-up metal 55 by extending and contracting in the front-rear direction. , And a motor 53 as an actuator connected so as to move the pusher 56 forward or backward by being rotationally driven. The motor 53 is electrically connected to the control device 20 so as to be driven and controlled by the control device 20. The rotation shaft of the motor 53 is connected to a potentiometer 54 that detects the rotation angle position of the rotation shaft so that drive transmission is possible via a gear. The rotation angle of the motor 53 detected by the potentiometer 54 corresponds to the forward / backward position of the pusher 56, that is, the swing angle of the ink key 7, and thus the ink key opening can be detected. The potentiometer 54 is electrically connected to the control device 20 so that the detection result is input to the control device 20.

  As described above, the ink key opening degree adjusting device 50 is configured to adjust the ink key opening degree by rotating the motor 53 and swinging the ink key 7 via the pusher 56 and the push-up bracket 55. Thus, the ink supply amount can be adjusted for each width unit (ink supply zone or key zone) of the ink key.

[Functional configuration of control system]
Next, the functional configuration of the control system of the printing press according to the present invention will be described with reference to FIGS.
As shown in FIG. 6, the control device 20 includes a memory such as a ROM and a RAM, and an arithmetic device such as a CPU. As the ink supply amount control means (ink supply amount control unit), a DSP (digital signal A processor, which has a function corresponding to a pixel-of-interest setting means, an image line ratio calculating means, and an actual mixed color halftone density measuring means) 31, a color conversion unit (target mixed color halftone density setting means, target image area ratio calculating means, target single color halftone density) An ink supply amount calculation unit 35 including an arithmetic unit, an actual image line ratio calculation unit, an actual monochromatic halftone density calculation unit, a solid density deviation calculation unit) 34, a correction unit (correction unit) 40, and an online control unit. 36, functional elements of a key opening limiter calculation unit 37 and an ink key control means (ink key control unit) 38 are provided.

As shown in FIG. 7, the correction unit 40 includes a correction determination unit 41, a high image rate zone selection unit 42, and a target ink supply amount correction unit 43 as functional elements.
The functional elements of the DSP 31, color conversion unit 34, ink supply amount calculation unit 35, online control unit 36, key opening limiter calculation unit 37, and ink key control means 38 are for each ink color (each ink supply device 5). In addition, each ink key is individually controlled.

  An IRGB densitometer 1, a potentiometer 54 and an input means 25 are connected to the input side of the control device 20, and an ink key opening degree adjusting device 50 is connected to the output side. The ink key opening adjustment device 50 is controlled by the ink key control means 38 and independently adjusts the ink key openings of the ink keys 7a to 7j of the printing units 2a, 2b, 2c, and 2d. Further, the line rate data in each key zone of the print pattern is input from the input means 25 and stored in the memory of the control device 20. That is, the control device 20 has a function as an image line ratio acquisition unit.

  FIG. 8 is a flowchart for explaining the ink supply amount control in the present embodiment, and is a flowchart showing a control flow of ink key opening degree control in which the print width direction position is the same position for each ink color. Hereinafter, the processing mode of the color tone control will be described with reference to FIG. In addition, although this color tone control demonstrates printing on the same printing surface (front surface here), the same control is performed also about printing of a back surface. Further, FIG. 8 shows processing for each ink color system corresponding to one key zone, and the processing shown in FIG. 8 is performed for each key zone.

In order to perform color tone control, it is necessary to determine some target value for feedback control. In this embodiment, since the reflection density, that is, the mixed color halftone density is measured using the line sensor type IRGB densitometer 1, in step S0, the target mixed color halftone density is set by the following procedure as the target value.
First, the image area ratios Ak, Ac, Am, and Ay data for each key zone of each ink color in the printed pattern are input from the input unit 25 to the control device 20. The drawing rate Ak, Ac, Am, Ay data can be obtained by measuring a film for plate making with a film scanner or by measuring a printing plate with a plate scanner. It can be easily obtained by using data. The color conversion unit 34 includes a database 39 that associates the image line ratio of each ink color with the mixed color halftone density. The database 39 is a printed paper based on the Japan Color Japan Color standard established by the ISO / TC130 National Committee, and measured with an IRGB densitometer [standard color streak rate (k, c, m, y) and mixed color density It is created on the basis of (a conversion table that defines the correspondence between I, R, G, B) and color coordinate values (L, a, b). The color conversion unit 34 uses this database 39 to obtain the mixed color halftone density corresponding to the input image line ratios Ak, Ac, Am, Ay for each key zone, and the target mixed color halftone density Io, Ro, Go, Bo. Set as.

  Note that even if the print pattern has the same line rate Ak, Ac, Am, or Ay, the color density depends on the density of the print pattern (50% flat screen, 80% flat screen, solid, etc.) considering the dot gain. Concentration value to be different. Accordingly, the color conversion unit 44 can change the dot gain for each density of the halftone, and the parameters with the dot gain as a function can be used to set the image ratios Ak, Ac, Am, Ay to the mixed color halftone densities Io, Ro, Go, Bo. The target color mixture density Io, Ro, Go, Bo considering the dot gain can be set.

  As described above, when the target color mixture halftone densities Io, Ro, Go, Bo are set, printing is started and the processes in and after step S10 are repeatedly executed. First, as step S10, the line sensor type IRGB densitometer 1 measures the reflected light amounts i ', r', g ', b' for each pixel on the entire surface of the print sheet 8. The reflected light amounts i ′, r ′, g ′, b ′ of each pixel measured by the IRGB densitometer 1 are input to the DSP 31.

In step S20, the DSP 31 performs a moving average of the reflected light amounts i ′, r ′, g ′, and b ′ of each pixel in units of a predetermined number of printed sheets, so that the reflected light amounts i, r of each pixel from which the noise component has been removed. , G, b are calculated. In step S30, the reflected light amounts i, r, g, and b are averaged for each key zone, and the mixed color halftone density (actual mixed color halftone density) I, R, G, B based on the reflected light amount of the blank paper portion is obtained. Calculate. For example, assuming that the reflected light amount of infrared light on the blank paper portion is ip and the average reflected light amount of infrared light in the key zone is ik, the actual mixed color halftone density I of infrared light is I = log ₁₀ (ip / ik) As required. The actual mixed color halftone densities I, R, G, and B for each key zone calculated by the DSP 11 are input to the color conversion unit 34.

  The color conversion unit 34 performs the processes of steps S40, S50, and S60. First, in step S40, each ink color image corresponding to the target mixed color halftone density Io, Ro, Go, Bo set in step S0 and the actual mixed color halftone density I, R, G, B calculated in step S30. Calculate the linearity respectively. For this calculation, the database 39 is used, and based on the correspondence stored in the database 39, the line ratio of each ink color corresponding to the target color mixture halftone density Io, Ro, Go, Bo is calculated as the target line ratio ko, co, It is calculated as mo, yo, and the image line ratio of each ink color corresponding to the actual mixed color halftone density I, R, G, B is calculated as the actual image line ratio k, c, m, y.

  Next, in step S50, the color conversion unit 34 calculates a single color halftone density of each ink color corresponding to the target image line ratios ko, co, mo, yo and the actual image line ratios k, c, m, y. To do. This calculation can be performed using a map as shown in FIG. FIG. 9 is an example of a map in which the monochromatic halftone density actually measured when the image line ratio is changed is plotted as a characteristic curve, and is created from data measured in advance. In the example shown in FIG. 9, by comparing the black target image rate ko and the actual image rate k with the map, the target single color halftone density Dako and the real single color halftone density Dak are obtained from the characteristic curves in the map. ing. In this way, the color conversion unit 34 obtains the target monochromatic halftone densities Dako, Dako, Damo, Dayo and actual monochromatic halftone densities Dak, Dac, Dam, Day for each ink color.

  Next, in step S60, the color conversion unit 34 sets the solid density deviation ΔDsk of each ink color corresponding to the deviation between the target monochrome color density Dako, Dako, Damo, Dayo and the actual monochrome color density Dak, Dac, Dam, Day. , ΔDsc, ΔDsm, ΔDsy are calculated. Note that the solid density also depends on the image line ratio. For the same monochromatic halftone density, the solid density decreases as the image line ratio increases. Therefore, the color conversion unit 34 performs calculations using a map as shown in FIG. FIG. 10 is an example of a map in which the monochromatic halftone density actually measured when the monochromatic solid density is changed is plotted as a characteristic curve for each line ratio, and is created from data measured in advance. The color conversion unit 34 selects a characteristic curve corresponding to the target drawing ratios ko, co, mo, yo for each ink color from the map shown in FIG. 10, and sets the target monochromatic halftone densities Dako, Dako, Damo to the selected characteristic curve. , Dayo and the real monochromatic halftone densities Dak, Dac, Dam, Day are obtained to obtain solid density deviations ΔDsk, ΔDsc, ΔDsm, ΔDsy. In the example shown in FIG. 14, when the target line drawing ratio ko of black is 75%, the target monochrome color density Dako and the actual monochrome color density Dak are checked against the map, so that the black color can be obtained from the 75% characteristic curve in the map. A solid density deviation ΔDsk is obtained.

The solid density deviations ΔDsk, ΔDsc, ΔDsm, ΔDsy of each ink color calculated by the color conversion unit 34 are input to the ink supply amount calculation unit 35.
In step S70, the ink supply amount calculation unit 35 calculates key opening deviation amounts ΔKk, ΔKc, ΔKm, ΔKy corresponding to the solid density deviations ΔDsk, ΔDsc, ΔDsm, ΔDsy. The key opening deviation amounts ΔKk, ΔKc, ΔKm, ΔKy are increments / decrements relative to the key openings Kk, Kc, Km, Ky of the ink keys 7 output to the printing control means 31 in the previous processing of step T110. As the line drawing ratio A, the one used in step S0 can be used. Specifically, the ratio kd (kd = ΔDs / Ds) of the solid density deviation ΔDs (ΔDsk, ΔDsc, ΔDsm, ΔDsy) with respect to the reference density Ds (Dsk, Dsc, Dsm, Dsy) is obtained, and the ratio to the image area ratio A is calculated. The key opening K for obtaining the reference concentration is obtained using an API function, and a key opening deviation amount ΔK (ΔK = kd × K) for making the solid concentration deviation ΔDs zero is obtained as a product of these. A target value for the ink supply amount is determined based on the key opening deviation amount ΔK.

Next, in step S80, the correction means 40 included in the ink supply amount calculation unit 35 determines whether or not correction related to the ink lateral flow is necessary in the key opening target value correction routine, and determines that correction is necessary. In this case, the ink supply amount target value is corrected. This key opening target value correction routine will be described in detail later.
In step S90, the online control unit 36 sends the key opening deviation amounts ΔKk, ΔKc, ΔKm, ΔKy calculated by the color conversion unit 34 from the print units 2a, 2b, 2c, 2d to the line sensor type IRGB densitometer 1. Correction is performed in consideration of the dead time until the time, the reaction time of the ink key 7 per hour, and the printing speed. This correction is detected by the IRGB densitometer 1 as a change in the amount of reflected light because the ink key 7 moves after the key opening signal is input, the key opening is changed, and the amount of ink supplied to the printing sheet 8 changes. It takes into account the time delay until As such an online feedback control system with a large dead time, for example, PI control with dead time compensation, fuzzy control, robust control and the like are optimal. The online control unit 36 is for online control in which the current key opening Kk0, Kc0, Km0, Ky0 is added to the corrected key opening deviation (online control key opening deviation) ΔKk, ΔKc, ΔKm, ΔKy. The key opening degrees Kk1, Kc1, Km1, and Ky1 are input to the key opening limiter calculation unit 47.

  In step S100, the key opening limiter calculation unit 47 performs correction for restricting the upper limit value for the online control key openings Kk1, Kc1, Km1, and Ky1 calculated by the online control unit 46. This is a process for restricting an abnormal increase in the key opening due to the estimation error of the color conversion algorithm (the processes of steps SS40, S50, and S60) particularly in the low image area. Then, in step S110, the key opening limiter calculating unit 47 transmits the key opening Kk, Kc, Km, Ky whose upper limit value is restricted to the ink key control unit 38 as a key opening signal.

  In step S120, the ink key control unit 38 controls the ink key opening degree adjusting device 50 based on the transmitted key opening degree signals Kk, Kc, Km, Ky, and each ink key of each printing unit 2a, 2b, 2c, 2d. Adjust the opening of 7. As a result, the ink supply amount of each ink color is controlled to match the target color tone for each key zone.

In step S130, when the print end signal is not input due to the operator's operation or the like (when printing is continued), the above-described processing (step S10 to step S120) is repeated, and the control ends when the print end signal is input. To do.
Here, the correction by the correction means 40 will be described.
The correction means 40 of the ink supply amount calculation unit 35 is a key zone (limit key zone) in which the ink density control is limited due to the lateral flow of ink for any of the key zones for each printing unit. If it has occurred, it is determined that ink lateral flow correction is necessary, and the key opening deviation amount calculated in step S70 is calculated for the key zone to be corrected. Correction is performed on ΔKk, ΔKc, ΔKm, and ΔKy. As a result, the key opening signals Kk, Kc, Km, and Ky (ie, corresponding to the ink supply amount target values) as the key opening target values transmitted in step S110 are corrected. . However, the key opening target value correction routine is a control performed for each ink supply zone of each ink color whose printing width direction is the same position.

A control flow (key opening degree target value correction routine) relating to ink lateral flow correction in the correction means 40 as step S80 will be described with reference to FIG.
1 will be described with reference to any one of the key zones in the same manner as in FIG. 8. Hereinafter, the reference numerals for the specific key zones will be described using the reference numerals of the corresponding ink keys 7. FIG.
First, in step T10, the correction determination unit 41 of the correction unit 40 performs control from each key zone (all ink color key zones having the same position in the print width direction) as a control target, respectively in the previous step T110. The key opening Kk, Kc, Km, Ky of each ink key 7 output to the ink key control unit 38 in the process is the lower limit value (here, the key opening 0), and the solid density deviations ΔDsk, ΔDsc, ΔDsm, ΔDsy are The presence / absence of a key zone (hereinafter referred to as a limit key zone) smaller than 0 (that is, the actual monochrome halftone density is greater than the target monochrome halftone density) is determined. The key opening deviations ΔKk, ΔKc, ΔKm, ΔKy may be used instead of the solid density deviation Ds, and the correction determination unit 41 sets the key opening Kk, Kc, Km, Ky of each ink key 7 to the lower limit value, In addition, it may be determined whether or not there is a key zone (limit key zone) in which the key opening deviations ΔKk, ΔKc, ΔKm, and ΔKy are smaller than 0 (that is, whether correction conditions are possible).

  This is a state in which the ink density in the key zone is larger than the target ink density while the target value of the ink supply amount is the lower limit value. That is, this is a case where the solid density deviation exceeds the allowable range (here, the solid density deviation 0). Here, the correction determination unit 41 functions as a print density determination unit. In such a limit key zone, it is difficult to control the ink density on the printing sheet 8 to the target density by controlling the ink supply amount in the limit key zone alone.

  If it is determined in step T10 that there is a limit key zone, the correction request flag signal is turned on in step T20, the key opening target value correction routine is exited, and the process proceeds to step S90. This correction request flag signal also includes information that can specify a key zone (that is, a limit key zone) that requires correction, and is used for control in other key zones (key zones having different positions in the print width direction). It is done. In other words, if there is a limit key zone, it can be determined that the influence of the ink lateral flow from other key zones is large, and in the subsequent step, the ink supply amount to the high image area ratio zone that causes the ink lateral flow. This is for correcting the decrease.

  Since the process of FIG. 1 is performed for each key zone, a plurality of limit key zones may occur. If any key zone other than itself is a limit key zone, the correction request flag signal is turned on (step T10), so the determination on the correction determination flag signal in step T30 is Yes. If there is no limit key zone in the zone, the correction request flag signal is not turned on, and after passing through the No route, the key opening target value correction routine is exited and the process proceeds to step S90.

  When it is determined in step T30 that the correction request flag signal is turned on, the high-image-ratio zone selection unit 42 of the correction unit 40 determines that the correction request flag signal is stored in the memory of the control device 20 in step T40. It is determined from the image line rate data of each color in the key zone whether any one of the ink colors has a key zone whose image line rate is larger than a preset threshold value M1, and the image line rate is determined from the preset threshold value M1. Is larger, it is selected as a correction target as a high image rate zone.

If none of the ink colors has a line drawing ratio greater than a preset threshold value M1, it is determined that the ink is not in a high line drawing ratio zone to be subjected to ink lateral flow correction, and the key opening target value correction is performed. Exit the routine and proceed to step S90.
The control according to step T40 will be specifically described with reference to FIG. FIG. 11 is a graph showing the image line ratio of the ink key 7 provided in the printing unit 2a. As shown in FIG. 11, the memory of the control device 20 stores the image area ratios Aka to Akj of the key zones corresponding to the ink keys 7a to 7j for each printing unit. The other printing units similarly store the image area ratios Aca to Acj (printing unit 2b), Ama to Amj (printing unit 2c), and Aya to Ayj (printing unit 2d) of each key zone. Then, the high image rate zone selection unit 42 selects a high image rate zone compared with a preset threshold value M1. At this time, all the key zones having a larger line ratio than the threshold M1 may be selected as the high line ratio zone, but only the key zone having the highest line ratio is selected as the high line ratio zone. Also good. In any case, only the key zone 7i is selected as the high image area ratio zone. This threshold value M1 is a threshold value for determining whether or not a key zone having a large ink supply amount has a large influence on the limit key zone due to the lateral flow of ink caused by the swinging of the ink swinging roller 12.

  Note that the threshold for selecting the high image area ratio zone may be uniformly set as the threshold M1, but as shown in FIG. 12, the threshold for the key zones 7c and 7e adjacent to the limit key zone 7d is set to the lowest. However, the threshold value may be set higher as the distance from the limit key zone 7d increases stepwise (threshold value M2). This is because the influence of the ink lateral flow is greatest as the key zone having a high image area ratio is closer to the limit key zone. In FIG. 12, the threshold value is increased stepwise with a constant increase amount ΔM, but the increase amount ΔM may be set variably.

  If it is determined in step T40 that any one of the key zones is a high image area ratio zone, as step T50, the target ink supply amount correction unit 43 sets the ink supply amount of the high image area ratio zone. As a correction amount for the target value (that is, the key opening deviation amount ΔK), a predetermined correction amount P1 for the key opening deviation amount ΔK is set in the direction of decreasing the key opening degree, and the target ink supply in the high image area ratio zone is set. Correct the amount by decreasing. Here, with respect to the ink key 7i, which is a high image area zone, the key opening deviation amount ΔKi is corrected by the correction amount P1 in the direction in which the ink key opening decreases.

  The predetermined correction amount P1 will be described. The predetermined correction amount P1 is set based on map data in which the correction amount P1 corresponding to the image line rate in the high image line rate zone is stored, for example. This map data is obtained by setting the value of the correction amount P1 so that the target value (here, the ink key opening deviation) of the ink supply amount in the high image area zone is within a preset allowable range.

  In other words, the correction applied to the correction amount P1 is intended to intentionally change the target value of the ink key opening that is originally considered to be the optimum value for such a zone. It will shift. However, the ink key opening (that is, the ink supply amount) may be within a certain range (allowable range) near the optimum value even if it is not the optimum value. Here, the correction amount P1 is set to the ink key opening target value. Is set to a value that does not deviate from this allowable range.

Generally, the allowable range of the ink key opening target value tends to become wider as the ink density is higher, i.e., the higher the drawing rate, and the allowable range corresponding to the printing rate is determined in advance based on the actual printing result. Based on this, a correction amount P1 corresponding to the image line rate is set, stored as map data, and the correction amount P1 is set corresponding to the image line rate.
In addition, since the allowable range according to the image line ratio may be slightly different depending on the ink color, the map data is preferably created for each ink color unit.

  In addition, the target ink supply amount correction unit 43 reduces the key opening by a predetermined correction amount P2 for all other ink color key zones simultaneously with the correction for the high image area ratio zone. The key opening deviation amount ΔK is corrected to decrease in the direction. This is a process for preventing the color tone (color mixing degree) on the printing sheet 8 from being disturbed if the ink supply amount of only one ink color is reduced. Accordingly, the correction amount P2 for each ink color is set based on the map data corresponding to the correction amount P1 for each ink color, and the color tone is disturbed on the print sheet 8 corresponding to the correction amounts P1 and P2. It is set to a value that does not occur.

  The correction amount P2 for the other ink colors is used to balance the tone with the correction amount P1 for the original ink color to be corrected, and may be substantially the same as the correction amount P1. Considering that the allowable range is slightly different depending on the color, map data for the correction amount P2 may be prepared and used separately from the correction amount P1. More simply, as a measure for preventing other ink colors from deviating from the allowable range, the correction amount P2 may be set to a predetermined amount or a predetermined ratio smaller than the correction amount P1.

  Since the printing machine and the ink supply method as one embodiment of the present invention are configured as described above, the ink density on the printing sheet is the target while the target value of the ink supply amount is the lower limit value. Is detected and the target value of the ink supply amount in the high-line-ratio zone is reduced and corrected, so that ink supply from the high-line-ratio zone to the limit-key zone by ink cross-flow Can be suppressed. As a result, an increase in ink density on the printing sheet 8 due to excessive supply of ink in the limit key zone can be suppressed, and ink smearing in the non-image area occurring on the printing sheet 8 can be prevented.

  In addition, the decrease correction of the target value of the ink supply amount is set to a correction amount so that the ink density in the high image area zone does not deviate from the allowable range by this decrease correction. Does not become too thin. Further, since the target value of the ink supply amount is reduced for all ink colors, it is possible to maintain a good color tone balance on the printing sheet 8.

[Others]
Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention.
For example, in the above-described embodiment, in a printing machine or the like that is less affected by the lateral flow of ink from a key zone that is far from the limit key zone, the high image area ratio zone selection unit 42 is configured so that only the key zone adjacent to the limit key zone is displayed. It is also possible to select a high-image-ratio zone for the target. In this case, it is preferable to use a threshold value M3 that is smaller than the threshold value M1 or M2 in the above-described embodiment. The selection may be made. Then, when the line drawing ratios of the adjacent key zones are both greater than the threshold value M3, the adjacent key zones may be selected as the high line drawing ratio zone, or only the key zone having the higher line drawing ratio. May be selected as the high image area ratio zone.

  In the above-described embodiment, when the high key rate zone is not selected and a limit key zone is detected, all but the limit key zone are detected regardless of whether the high key rate zone is detected. The target value of the ink supply amount may be corrected to decrease with respect to the key zone. At least, when the target value of the ink supply amount in a certain key zone is less than or equal to a predetermined lower limit value, the target values of other key zones may be decreased. By doing in this way, control concerning ink lateral flow correction can be simplified.

It is a flowchart explaining the ink horizontal flow correction | amendment in the ink supply amount control as one Embodiment of this invention. 1 is a schematic side view illustrating a schematic configuration of a printing press including an ink supply device according to an embodiment of the present invention. It is a typical side view showing the composition concerning the ink supply from the ink supply device of the printing machine as one embodiment of the present invention to the plate cylinder. It is a typical side view showing composition of an ink supply device of a printing machine as one embodiment of the present invention. It is a typical side view showing composition of an ink supply device of a printing machine as one embodiment of the present invention. It is a block diagram which shows the function structure of the control system concerning ink supply amount control as one Embodiment of this invention. It is a block diagram which shows the function structure of the control system concerning ink lateral flow correction | amendment in the ink supply amount control as one Embodiment of this invention. It is a flowchart which shows the control flow of the ink supply amount control as one Embodiment of this invention. 6 is a map associating a monochrome halftone density with an image line ratio as one embodiment of the present invention. 6 is a map associating a solid density as an embodiment of the present invention with a line rate and a monochrome halftone density. It is a graph which shows the line drawing rate of each ink key 7 as one Embodiment of this invention. It is a graph which shows the line drawing rate of each ink key 7 as a modification of one Embodiment of this invention. It is a typical perspective view which shows the structure concerning the ink supply from an ink supply apparatus to a plate cylinder in the conventional printing machine.

Explanation of symbols

1 IRGB densitometer (ink sensor)
2a, 2b, 2c, 2d Printing unit 3 Blanket cylinder 4, 104 Plate cylinder 5 Ink supply device 6, 106 Ink source rollers 7, 7a, 7b, 7c, 7d, 7e, 7f, 7g, 7h, 7i, 7j Ink key 8 Printing sheet 9, 109 Ink transfer roller 10a, 10b Side plate 11, 111 Ink kneading roller group 12, 112 Ink swing roller 13, 113 Ink roller 20 Controller 31 DSP
34 Color conversion unit 35 Ink supply amount calculation unit 46 Online control unit 37 Key opening limiter calculation unit 38 Ink key control unit 39 Database 40 Correction means 41 Correction determination unit 42 High image rate zone selection unit 43 Target ink supply amount correction unit 50 Ink key opening adjustment device 51 Support shaft 53 Motor 54 Potentiometer (Ink key opening acquisition means)
55 Push-up bracket 56 Pusher

Claims (13)

An ink supply device for supplying ink to each ink supply zone divided in the printing width direction during printing;
Target value setting means for setting a target value of the ink supply amount for each of the ink supply zones based on the printing result is provided, and the ink supply device is arranged so that the ink supply amount of each ink supply zone becomes the target value. An ink supply amount control means for controlling,
The ink supply amount control means is
Image line rate acquisition means for acquiring the image line rate of the printed pattern of each ink supply zone;
When the target value of the ink supply amount in any one of the ink supply zones has reached the lower limit value and the ink density of the printed sheet exceeds the allowable range, the image ratio acquisition means A high image area ratio that has a image area ratio higher than a preset image area ratio threshold is selected from the image area ratios of the ink supply zones acquired by the above, and the target value of the high image area zone is set to A printing machine comprising correction means for reducing and correcting by a predetermined correction amount. Only one stroke rate threshold is set,
2. The printing press according to claim 1, wherein all of the ink supply zones having a higher image area ratio than the image area ratio threshold are selected as the high image area zone. Only one stroke rate threshold is set,
When there are a plurality of ink supply zones having a higher image drawing rate than the image drawing rate threshold value, the ink supply zone having the highest image drawing rate is selected as the high image drawing rate zone. The printing machine according to claim 1. The image line ratio threshold is set to a smaller value as the ink supply zone is closer to the ink supply zone where the target value has reached the lower limit value or less.
2. The printing press according to claim 1, wherein all the ink supply zones that have a line drawing rate higher than the corresponding line drawing rate threshold are selected as the high image drawing rate zone. . An ink supply device for supplying ink to each ink supply zone divided in the printing width direction during printing;
Target value setting means for setting a target value of the ink supply amount for each of the ink supply zones based on the printing result is provided, and the ink supply device is arranged so that the ink supply amount of each ink supply zone becomes the target value. An ink supply amount control means for controlling,
The ink supply amount control means is
Image line rate acquisition means for acquiring the image line rate of the printed pattern of each ink supply zone;
The one ink supply zone when the target value of the ink supply amount in any one of the ink supply zones has reached the lower limit value and the ink density of the printed sheet exceeds the allowable range. For the ink supply zone adjacent to the high-line-rate zone in which the image-line rate is higher than a preset image-line rate threshold, based on the image-line rate of each ink-supply zone acquired by the image-line-rate acquiring unit. And a correction means for reducing and correcting the target value of the adjacent ink supply zone by a predetermined correction amount if the adjacent ink supply zone is the high image area ratio zone. A printing machine. The printing machine is a multicolor offset printing machine,
The ink supply device and the ink supply amount control means are provided for each ink color printing device,
When the correction means of the ink supply amount control means for any one of the ink colors corrects the target value of the high image area rate zone by the correction amount, the correction means for the other ink colors 6. The printing press according to claim 1, wherein a target value of an ink supply zone corresponding to the high image area ratio zone is corrected according to the correction amount. The printing press according to claim 1, wherein the predetermined correction amount is a value having the target value as an allowable lower limit value. The ink supply device includes a plurality of ink keys arranged in parallel in the printing width direction, and supplies ink to each of the ink supply zones divided for each ink key during printing,
The ink supply amount control means is
A target color mixture density setting means for setting a target color mixture density of the printed pattern for each ink supply zone;
An IRGB densitometer disposed on a travel line of the print sheet obtained by printing;
An actual color mixture halftone density measuring means for operating the IRGB densitometer to measure an actual color mixture halftone density for each ink supply zone of the printing sheet;
A target halftone dot area ratio calculating means for obtaining a target halftone dot area ratio of each ink color corresponding to the target mixed color halftone density based on a correspondence relationship between a predetermined halftone dot area ratio and mixed color halftone density;
Based on the correspondence between the halftone dot area ratio and the mixed color halftone density, an actual halftone dot area ratio calculating means for obtaining an actual halftone dot area ratio of each ink color corresponding to the actual mixed color halftone density;
A target monochromatic halftone density calculating means for obtaining a target monochromatic halftone density corresponding to the target halftone dot area ratio based on a correspondence relationship between a predetermined halftone dot area ratio and a monochromatic halftone density;
Based on the correspondence between the halftone dot area ratio and the single color halftone density, an actual single color halftone density calculating means for obtaining an actual single color halftone density corresponding to the actual halftone dot area ratio;
Based on a correspondence relationship between a predetermined halftone dot area ratio, a monochrome halftone density, and a solid density, a solid corresponding to a deviation between the target monochrome halftone density and the actual monochrome halftone density under the target halftone dot area ratio. A solid density deviation calculating means for obtaining a density deviation;
The printing machine according to claim 1, wherein the target value setting unit sets a target value of the ink supply amount based on the solid density deviation. A print density for determining whether or not the ink density is within a preset allowable range by comparing the solid density deviation obtained by the solid density deviation calculating means with a preset determination reference value. A determination means,
9. The printing press according to claim 8, wherein the determination as to whether or not the ink density exceeds an allowable range is made based on a determination result of the print density determination means. A printing density determination means for determining whether or not the ink density of the printing sheet is within a preset allowable range for each ink supply zone;
The printing press according to any one of claims 1 to 7, wherein the determination as to whether or not the ink density exceeds an allowable range is made based on a determination result of the print density determination means. . In an ink supply device that is installed in a printing press and supplies ink for each ink supply zone divided in the printing width direction during printing, a target value for the ink supply amount is set for each ink supply zone based on the printing result, An ink supply amount control method for controlling the ink supply device so that the ink supply amount of each ink supply zone becomes the target value,
An image line rate acquisition step of acquiring an image line rate of the printed pattern of each ink supply zone;
Any one of the ink supply zones satisfies the correction condition that the target value of the ink supply amount has reached the lower limit (0) and that the ink density of the printed sheet exceeds the allowable range. A correction condition determining step for determining whether or not
When it is determined in the correction condition determination step that the correction condition is satisfied, the image line ratio of each ink supply zone acquired in the image line ratio acquisition step is determined based on a predetermined image line ratio threshold value. A correction step of selecting a high-drawing-rate zone with a high drawing-line ratio and reducing the target value of the high-drawing-rate zone by a predetermined correction amount. Ink supply method. In an ink supply device that is installed in a printing press and supplies ink for each ink supply zone divided in the printing width direction during printing, a target value for the ink supply amount is set for each ink supply zone based on the printing result, An ink supply amount control method for controlling the ink supply device so that the ink supply amount of each ink supply zone becomes the target value,
An image line rate acquisition step of acquiring an image line rate of the printed pattern of each ink supply zone;
Any one of the ink supply zones satisfies the correction condition that the target value of the ink supply amount has reached the lower limit (0) and that the ink density of the printed sheet exceeds the allowable range. A correction condition determining step for determining whether or not
When it is determined by the correction condition determination step that the correction condition is satisfied, the ink supply zone adjacent to the one ink supply zone is determined for each of the ink supply zones acquired by the image line ratio acquisition unit. From the image line rate, it is determined whether or not it is a high image line rate zone whose image line rate is higher than a preset image line rate threshold, and if the adjacent ink supply zone is the high image line rate zone, An ink supply method for a printing press, comprising: a correction step for reducing and correcting the target value of the adjacent ink supply zone by a predetermined correction amount. An ink supply device for supplying ink to each ink supply zone divided in the printing width direction;
Target value setting means for setting a target value of the ink supply amount for each ink supply zone;
An ink supply amount control means for controlling the ink supply device according to the target value,
The ink supply amount control means is
When the target value of the ink supply amount of the first ink feed zone of said ink supply zone is equal to or less than a predetermined lower limit value, the ink supply amount of the other ink feed zone of the ink supply zone of the 1 A printing machine characterized by reducing a target value.

Images