JP4022233B2 - Method and apparatus for detecting background contamination of printed matter, and control method and apparatus for printing press - Google Patents

Description

  The present invention relates to a background detection method and apparatus for detecting background stains of printed matter, and a control method and apparatus for a printing press that suppresses the occurrence of background stains of printed matter by using the background detection method and apparatus.

  When printing with ink, as shown in FIG. 7, there is a stain (hereinafter also referred to as a ground stain or an ink stain) due to the ink adhering to the ground portion of the printing paper that should not have ink attached. May occur. In FIG. 7, the background stain 63 is exaggeratedly shown in the blank area (non-image area) 62 of the print image 60, but the background dirt 63 is also generated in the pattern area (image area) 61. To do. Such scumming is often caused by insufficient supply of dampening water to the printing cylinder (plate cylinder, blanket cylinder). In many cases, it can be suppressed.

Printing is simple when using single color ink. For example, in the case of full color printing, four colors of black (black k), indigo (cyan c), red (magenta m), and yellow (yellow y) are used. Since the ink is used, it is necessary to specify the color of the background ink and increase the supply amount of dampening water to the printing cylinder of the printing unit for the specified ink.
Therefore, the operator can check the printed matter, and if the soiling occurs, the operator can visually determine how many colors are dirty and increase the amount of dampening water supplied to the dirty printing unit. .

However, in the method of detecting the background stain by the operator's visual observation, if the operator overlooks the background stain, all the printed matter until the subsequent detection of the background stain is lost. In particular, when a high-quality printed matter is required, even if there is a slight background smudge, it cannot be turned into a regular sheet and must be broken, leading to an increase in cost and an increase in printing time.
Of course, if the operator performs a visual check with high accuracy, these problems can be suppressed, but detection of slight scumming is not easy and the burden on the operator becomes extremely large.

Further, even if the background stain can be detected, it may be difficult to determine how many colors are dirty. For example, if ink color and indigo color, red color, or yellow color overlap and become dirty, a color other than the ink color may be overlooked.
It is also effective to increase the supply amount of dampening water to suppress the occurrence of scumming. However, if the supply of dampening water is increased too much, it becomes over-emulsified and the ink is leached into the dampening water. This causes problems such as so-called floating stains in which bleeding occurs at the boundary between the portion and the non-image portion, and a roller stripping phenomenon in which ink does not adhere to the ink roller.

  The present invention has been devised in view of such problems, and it is possible to determine the color of background dirt without relying on an operator, and the occurrence of background dirt without causing other problems. An object of the present invention is to provide a background and method for detecting a soiled printed matter, and a control method and apparatus for a printing press, which can suppress the above-described problem.

  In order to achieve the above-mentioned object, the background detection method for printed matter of the present invention uses an IRGB densitometer to detect whether there is ink stain on the non-image area of the printed matter and to actually mix the ink stain with ink stain. The actual halftone dot area ratio of each ink color corresponding to the actual mixed color halftone density is obtained based on the actual mixed color halftone density measuring step for measuring the halftone density and the correspondence relationship between the preset halftone dot area ratio and the mixed color halftone density. The actual halftone dot area ratio calculating step, and comparing the actual halftone dot area ratio of each of the ink colors with a preset threshold value, if there is an ink color with the actual halftone dot area ratio exceeding the threshold value, And a stain determination step for determining that the ink color exceeds the threshold value. (Claim 1).

  In the color mixture halftone density measurement step, a measurement area is set except for a portion within a predetermined distance adjacent to the image line portion of the printed material among the non-image line portions of the printed material, and the actual color mixture with respect to the measurement area It is preferable to measure the net density (claim 2). At this time, the setting of the measurement area may be performed based on pre-obtained plate making data, or may be performed based on the image at the time of the OK sheet.

The correspondence between the halftone dot area ratio and the mixed color halftone density is a correspondence defined by the Neugebauer equation, and is measured in the actual mixed color halftone density measurement step in the actual halftone dot area ratio calculation step. It is preferable to determine the actual halftone dot area ratio of each ink color corresponding to the actual mixed color halftone density by substituting the actual mixed color halftone density into the Neugebauer equation.
In this case, the Neugebauer equation is expressed by k, c, m, y solid and k, c, m, y solid kc, km, ky, cm, cy, my, kcm, kcy, kmy, It is preferable that a color chart composed of cmy and kcmy is constructed by substituting a solid density value obtained in advance using the IRGB densitometer (claim 4). Alternatively, the Neugebauer equation can be expressed as k, c, m, y, and kc, km, ky, cm, cy, my, kcm, kcy, kmy, cmy obtained by superimposing these k, c, m, y nets. , Kcmy is preferably constructed by substituting a density value obtained in advance using the IRGB densitometer.

  Further, the correspondence relationship between the halftone dot area ratio and the mixed color halftone density is a correspondence relation defined by the extended Neugebauer formula that incorporates the Yule-Nielsen formula into the Neugebauer formula, and in the actual halftone dot area ratio calculation step, It is preferable to obtain an actual halftone dot area ratio of each ink color corresponding to the actual mixed color halftone density by substituting the actual mixed color halftone density measured in the actual mixed color halftone density step into the extended Neugebauer equation. 6). In this case, the extended Neugebauer equation is obtained by superimposing k, c, m, y solids and k, c, m, y solids kc, km, ky, cm, cy, my, kcm, kcy, kmy. , Cmy, and kcmy are preferably constructed by substituting a solid density value obtained in advance by using the IRGB densitometer into a color chart (claim 7). Alternatively, the extended Neugebauer equation can be expressed as kc, km, ky, cm, cy, my, kcm, kcy, kmy, and k, c, m, y nets. It is preferable that a color chart composed of cmy and kcmy is constructed by substituting a density value obtained in advance using the IRGB densitometer (claim 8).

  The control method of the printing press according to the present invention includes the steps according to any one of claims 1 to 8, and if it is determined which of the ink colors is stained on the printed matter, the corresponding ink color And a dampening water supply amount adjusting step for adjusting the dampening water supply means of the printing unit to adjust the dampening water supply amount to the scumming suppression side (basically, the increase side). It is characterized (claim 9).

  The dampening water supply means is capable of adjusting the dampening water supply amount in units of a plurality of areas divided in the axial direction of the printing cylinder, and in the actual halftone dot area ratio calculation step, in the area unit The actual halftone dot area ratio of each ink color is obtained for each area according to the above, and in the stain determination step, the stain of each ink color is determined for each area according to the area unit, and the dampening water supply amount adjustment is performed. In the step, it is preferable to adjust the dampening water supply amount in units of the above-mentioned areas (claim 10).

In the dampening water supply amount adjusting step, it is preferable to increase the dampening water supply amount by a predetermined amount when ink stain is determined.
Furthermore, it is preferable that an upper limit value is set for the dampening water supply amount, and in the dampening water supply amount adjustment step, increase control of the dampening water supply amount is performed within the upper limit value (claim 12).
In addition, after the dampening water supply amount adjustment step is performed once, it is preferable to perform the stain determination step after waiting for printing for a preset number of sheets (claim 13).

  The background detection device for printed matter according to the present invention includes an IRGB densitometer arranged on a travel line of a printed sheet obtained by printing, and a mixed color that measures the actual mixed color halftone density of the printed sheet by operating the IRGB densitometer. 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 a correspondence relationship between the halftone dot density measuring means and a preset halftone dot area ratio and the mixed color halftone density. And comparing the actual halftone dot area ratio of each ink color with a preset threshold value, and if there is an ink color with the actual halftone dot area ratio exceeding the threshold value, the ink color exceeding the threshold value The present invention is characterized in that it is provided with a dirt judging means for judging that there is dirt (claim 14).

  In the mixed color halftone density measuring means, a measurement area is set based on pre-obtained plate making data, excluding a portion within a predetermined distance adjacent to the image line portion of the printed material among the non-image area of the printed material. Preferably, the actual mixed color halftone density is measured for the measurement area. At this time, as described above, the setting of the measurement area may be performed based on plate making data obtained in advance, or may be performed based on the image at the time of the OK sheet.

  The correspondence relationship between the halftone dot area ratio and the mixed color halftone density is a correspondence relation defined by the Neugebauer equation, and the actual halftone dot area ratio calculating means is the actual mixed color halftone network measured by the mixed color halftone density measuring means. It is preferable to determine the actual halftone dot area ratio of each ink color corresponding to the actual mixed color halftone density by substituting the density into the Neugebauer equation. In this case, the Neugebauer equation is expressed by k, c, m, y solid and k, c, m, y solid kc, km, ky, cm, cy, my, kcm, kcy, kmy, It is preferable that a color chart composed of cmy and kcmy is constructed by substituting a solid density value obtained in advance using the IRGB densitometer (claim 17). Alternatively, the Neugebauer equation can be expressed as k, c, m, y, and kc, km, ky, cm, cy, my, kcm, kcy, kmy, cmy obtained by superimposing these k, c, m, y nets. , Kcmy is preferably constructed by substituting a color density value obtained in advance using the IRGB densitometer into a color chart composed of kcmy (claim 18).

  The correspondence relationship between the halftone dot area ratio and the mixed-color halftone density is a correspondence relation defined by the extended Neugebauer formula that incorporates the Yule-Nielsen formula into the Neugebauer formula. It is preferable to obtain the actual halftone dot area ratio of each ink color corresponding to the actual mixed color halftone density by substituting the actual mixed color halftone density measured by the halftone density measuring means into the extended Neugebauer equation. . In this case, the extended Neugebauer equation is obtained by superimposing k, c, m, y solids and k, c, m, y solids kc, km, ky, cm, cy, my, kcm, kcy, kmy. , Cmy, and kcmy are preferably constructed by substituting a solid density value obtained in advance using the IRGB densitometer. Alternatively, the extended Neugebauer equation can be expressed as kc, km, ky, cm, cy, my, kcm, kcy, kmy, and k, c, m, y nets. It is preferable that a color chart composed of cmy and kcmy is constructed by substituting a density value obtained in advance using the IRGB densitometer (claim 21).

  A control device for a printing press according to the present invention includes a ground detection device for printed matter according to any one of claims 14 to 21, and a dampening water supply means capable of adjusting a dampening water supply amount supplied to a printing cylinder. When the background detection device determines whether there is any ink color background stain on the printed material, the dampening water supply amount of the corresponding ink color printing unit is set to the background side. And a control means for controlling the dampening water supply means (claim 22).

  The fountain solution supply means is capable of adjusting the fountain solution supply amount in units of a plurality of areas divided in the axial direction of the printing cylinder. The actual halftone dot area ratio of each ink color is determined for each area corresponding to the ink color, and the stain determination means determines the stain of each ink color for each area corresponding to the area unit. It is preferable that the dampening water supply amount is adjusted in units of the above areas with respect to the water supply device (claim 23).

Preferably, the control means increases the supply amount of dampening water by a predetermined amount when ink stain is determined.
It is preferable that an upper limit value is set for the fountain solution supply amount, and that the control means performs an increase control of the fountain solution supply amount within the upper limit value (Claim 25).
In addition, after the dampening water supply amount adjusting unit once adjusts the dampening water supply amount, the stain determination unit performs the stain determination after waiting for printing for a preset number of sheets. It is preferable to implement (claim 26).

According to the background detection method (Claim 1) and the apparatus (Claim 14 ) of the printed matter of the present invention, it is easy and sure to determine which ink is smudged even when a smear of a plurality of inks is generated. be able to. In addition, since the stain is detected by paying attention to the non-image portion (that is, the blank paper portion) of the printed matter, the detection accuracy is high.
The non-image area of the printed material is set to the measurement area excluding the area adjacent to the image area of the printed material within a predetermined distance, and the adjacent image area is stained by mistake by measuring the actual mixed color halftone density. Can be prevented (claims 2 and 15).

  Also, the correspondence between the dot area ratio and the mixed color halftone density is a correspondence defined by the Neugebauer formula, and each ink color corresponding to the actual mixed color halftone density is obtained by substituting the actual mixed color halftone density into the Neugebauer formula. Therefore, the actual halftone dot area ratio can be easily obtained from the actual mixed color halftone density by calculation (claims 3 and 16). At this time, the Neugebauer formula is k, c, m, y solid and k, c, m, y, and solid kc, km, ky, cm, cy, my, kcm, kcy, kmy, cmy. , Kcmy is calculated by substituting a solid density value obtained by using an IRGB densitometer in advance, the actual halftone dot area ratio is calculated in a color space corresponding to the solid density value. (Claims 4 and 17). In addition, the Neugebauer equation is a network of k, c, m, y and kc, km, ky, cm, cy, my, kcm, kcy, kmy, cmy, which are obtained by superimposing these k, c, m, y nets. If a color chart composed of kcmy is constructed by previously substituting the halftone density value obtained using an IRGB densitometer, the actual halftone dot area ratio can be calculated in the color space corresponding to the halftone density value. it can. In other words, the actual halftone dot area ratio can be calculated with high accuracy in a color space smaller than the color space corresponding to the solid density value, thereby making it possible to detect thinner background stains (claims 5 and 18).

  The correspondence relationship between the halftone dot area ratio and the mixed-color halftone density is a correspondence relation defined by the extended Neugebauer formula that incorporates the Yule-Nielsen formula into the Neugebauer formula, and by substituting the actual mixed-color halftone density into the extended Neugebauer formula Since the actual halftone dot area ratio of each ink color corresponding to the actual mixed color halftone density is obtained, the actual halftone dot area ratio can be easily obtained from the actual mixed color halftone density by calculation, and when dark background stains occur, Even when the halftone dot area ratio obtained by the calculation is 100% or more, there is a halftone dot area ratio solution, and an accurate real halftone dot area ratio can be calculated (claims 6 and 19). At this time, the extended Neugebauer formula is k, c, m, y solid and these k, c, m, y solid superimposed kc, km, ky, cm, cy, my, kcm, kcy, kmy, If a color chart composed of cmy and kcmy is constructed by substituting a solid density value obtained beforehand using an IRGB densitometer, an actual halftone dot area ratio is calculated in a color space corresponding to the solid density value. (Claims 7 and 20). In addition, the extended Neugebauer equation is k, c, m, y, and kc, km, ky, cm, cy, my, kcm, kcy, kmy, cmy obtained by superimposing these k, c, m, y nets. , Kcmy is calculated by substituting the halftone density value previously obtained by using an IRGB densitometer, the actual halftone dot area ratio is calculated in the color space corresponding to the halftone density value. Can do. In other words, the actual halftone dot area ratio can be accurately calculated in a color space smaller than the color space corresponding to the solid density value, and thereby thinner background stains can be detected (claims 8 and 21).

According to the control method (Claim 9) and the apparatus (Claim 22) of the printing press according to the present invention, it is possible to appropriately determine which color printing unit is in a dampening water supply amount state in which soiling occurs. Since the amount of water supply is adjusted, the occurrence of soiling can be reliably prevented.
When the dampening water supply amount can be adjusted in units of multiple areas divided in the axial direction of the printing cylinder, the actual halftone dot area ratio of each ink color was obtained for each area, and the stain of each ink color was judged. In the above, the dampening water can be adjusted with higher accuracy by adjusting the dampening water supply amount for each area (claims 10 and 23).

Also, when ink smear is judged, most of the ink smears are caused by insufficient dampening water supply, so increasing the dampening water supply by a predetermined amount can prevent ink smearing. (Claims 11 and 24).
At this time, if the supply amount of dampening water is excessive, it becomes over-emulsified and causes problems such as floating dirt and roller stripping, but an upper limit value is set for the dampening water supply amount, and the dampening solution is dampened within the upper limit value. Such an inconvenience can be avoided by performing an increase control of the water supply amount (claims 12 and 25).

  In addition, even if the dampening water supply amount is adjusted, it takes time until ink stains are eliminated, but after adjusting the dampening water supply amount once in this way, only the preset number of sheets is set. After waiting for printing to be performed, the stain determination is performed and the next dampening water supply amount adjustment is performed. Therefore, the control can be performed appropriately (claims 13 and 26).

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a printed matter background contamination detection method and apparatus and a printing press control method and apparatus according to an embodiment of the present invention will be described with reference to the drawings.
(A) First Embodiment FIG. 1 is a diagram showing a schematic configuration of a newspaper offset rotary press according to a first embodiment of the present invention. The newspaper web offset press of this embodiment is a multi-color printing duplex printing machine, and ink colors [black (k), indigo (c), red (m), yellow (y )] Is provided for each printing unit 2a, 2b, 2c, 2d. In the present embodiment, the printing units 2 a, 2 b, 2 c, and 2 d are provided with an ink key type ink supply device that includes an ink key 7 and an ink base roller 6. In this type of ink supply apparatus, the ink supply amount can be adjusted by the amount of gap between the ink key 7 and the ink base roller 6 (hereinafter, this gap amount is referred to as the ink key opening).

  A plurality of ink keys 7 are juxtaposed in the printing width direction, and the ink supply amount can be adjusted in the width unit of the ink key 7 (hereinafter, the ink supply unit width by the ink key 7 is referred to as a key zone). The ink whose supply amount is adjusted by the ink key 7 is appropriately kneaded in the ink roller group 5, and after being formed into a thin film, is supplied to the plate surface of the plate cylinder 4 through the ink form roller 9, and the ink adhered to the plate surface The image is transferred to the print sheet 8 as a pattern through the blanket cylinder 3. Although not shown in FIG. 1, the newspaper offset rotary press of this embodiment is a double-sided printing, and therefore a pair of printing units 2 a, 2 b, 2 c, and 2 d is provided so as to sandwich the conveyance path of the printing sheet 8. Blanket cylinders 3 and 3 are provided, and a plate cylinder 4, an ink supply device, and a fountain solution supply device 70 are provided for each blanket cylinder 3.

  The newspaper offset rotary press of this embodiment includes a line sensor type IRGB densitometer 1 further downstream of the most downstream printing unit 2d. The line sensor type IRGB densitometer 1 reflects I (infrared light), R (red), G (green), and B (blue) reflection densities (mixed-color network) in the form of a line in the print width direction of the pattern color on the printing sheet 8. It is possible to measure the reflection density of the entire print sheet 8 or to measure the reflection density at an arbitrary position. Since the newspaper offset rotary press of this embodiment is a double-sided printing, the line sensor type IRGB densitometer 1 is arranged on both the front and back sides so as to sandwich the conveyance path of the printing sheet 8, and the reflection density on both the front and back sides can be measured. .

The reflection density measured by the line sensor type IRGB densitometer 1 is transmitted to the arithmetic unit 10. The calculation device 10 also functions as a device for calculating the control data of the ink supply amount. Here, when there is a background stain, it is determined what color ink is the background stain, and based on this, the dampening is performed. It functions to adjust the water supply amount Qw.
As shown in FIGS. 1 and 2, the dampening water supply device 70 includes a water source roller 71, a water reciprocating roller 72, a water application roller 73, and a water spray device 74, and a dampening water is supplied from a nozzle 74 a of the water spray device 74. The fountain solution can be supplied to the plate cylinder (printing cylinder) 4 through the water reciprocating roller 72 and the water-filling roller 73 by spraying the water on the water source roller 71. A plurality of nozzles 74 a of the water spray device 74 are provided in a pipe 75 extending in the axial direction of the water source roller 71 along the axial direction of the water source roller 71, and each nozzle 74 is individually or adjacent to each other. The amount of injection can be controlled for each group in which a plurality of nozzles are grouped. Accordingly, the dampening water supply amount Qw can be adjusted in units of a plurality of areas divided in the axial direction of the plate cylinder 4. Covers 76 and 76 are provided on the outer sides of the nozzles 74a at both ends, thereby preventing the fountain solution from splashing outside the machine.

  Here, the nozzle 74a of the left group 74L and the nozzle 74a of the right group 74R can be controlled separately in the left and right groups. The dampening water supply amount Qw can be adjusted. Further, the dampening water supply amount Qw is specifically controlled as a dampening water injection amount (injection amount per unit time) from the nozzle.

Reference is now made to FIG. FIG. 3 is a diagram showing a schematic configuration of the pattern color tone control device for the newspaper offset rotary press according to the first embodiment of the present invention, and at the same time, pays attention to the control function for adjusting the dampening water supply amount of the arithmetic unit 10. FIG.
The arithmetic unit 10 is composed of a DSP (digital signal processor) 11 and a PC (personal computer) 12 that are installed apart from the printing press. The PC 12 includes a color conversion unit 14, a stain determination unit 15, and a dampening water amount. A function as the setting unit 16 is assigned. The line sensor type IRGB densitometer 1 is connected to the input side of the arithmetic device 10, and the control device 20 with a built-in printing press is connected to the output side. The control device 20 functions as a dampening water supply amount adjusting means that adjusts the dampening water supply amount Qw in units of a plurality of areas divided in the axial direction of the plate cylinder 4. The operation of the water spray device 74 can be adjusted. Further, a touch panel 30 as a display device is connected to the arithmetic device 10. On the touch panel 30, the print surface of the print sheet 8 imaged by the line sensor type IRGB densitometer 1 is displayed, and an arbitrary area on the print surface can be selected with a finger.

FIG. 5 is a diagram showing a processing flow of the soiling determination by the arithmetic unit 10 and the dampening water supply amount adjustment performed based on this determination. Hereinafter, the processing content of the color tone control by the arithmetic unit 10 will be described with reference to FIG.
During printing, the processes after step S10 shown in FIG. 5 are repeatedly executed. First, as step S10, the line sensor type IRGB densitometer 1 measures the amount of reflected light i ′, r ′, g ′, b ′ for each pixel on the entire surface of the printing sheet 8. The reflected light amounts i ′, r ′, g ′, b ′ of each pixel measured by the IRGB densitometer 1 are input to the DSP 11.

In step S20, the DSP 11 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 target is specified as a blank area (non-image area), the reflected light amounts i, r, g, and b are processed for each pixel in the dampening water adjustment zone, and the reflected light amount of the blank paper portion is determined. The reference mixed color halftone density (actual mixed color halftone density) I, R, G, B is calculated. For the mixed color halftone density (actual mixed color halftone density) I, R, G, and B, for example, the reflected light amount of the infrared light of the white paper portion is assumed to be ip, and the average reflected light amount of the infrared light in the dampening solution adjustment zone. Is ik, the actual mixed color halftone density I of infrared light is obtained as I = log 10 (ip / ik).

The reason why the target is specified as a blank area (non-image area) is because it is difficult for the image area to distinguish between image lines and dirt. That is, in the blank area, the actual mixed color halftone density is 0 if there is no stain, but the actual mixed color halftone density is a positive value if there is stain. Accordingly, it is possible to determine the presence or absence of dirt from the actual mixed color halftone density value.
The location of the blank area of the printing paper can be recognized from the plate making data. Here, the DSP 11 identifies the location of the blank area of the printing paper from the plate making data and automatically sets it as the calculation area (measurement area). When an OK sheet is obtained, this setting can be set manually by looking at the image of the OK sheet.

  Also, even in the blank area (non-image area), the portion adjacent to the pattern area (image area) may be a blank area on the plate making data due to a detection position shift accompanying high-speed conveyance of printing paper. Actually, there is an image line portion, which may be detected. Therefore, in the DSP 11, as shown by the broken line in FIG. 4, the portion of the blank area (non-image portion) 52 of the plate-making image 50 that is close to the pattern area (image portion) 51 within a predetermined distance is excluded. Thus, an area (measurement area) 53 for calculating the mixed color halftone density (actual mixed color halftone density) I, R, G, B is set, and the actual mixed color halftone density is calculated (measured) for this measurement area 53. ing.

  As described above, the actual mixed color halftone densities I, R, G, and B for each dampening water adjustment zone in the blank paper area calculated by the DSP 11 are input to the color conversion unit 14 of the PC 12. The color conversion unit 14 performs the process of step S40. In step S40, the halftone dot area ratio of each ink color corresponding to the actual mixed color halftone density I, R, G, B calculated in step S30 is calculated. For this calculation, the database 141 is used, and based on the correspondence stored in the database 141, the halftone dot area ratio of each ink color corresponding to the actual mixed color halftone density I, R, G, B is calculated as the actual halftone dot area ratio k, Calculate as c, m, y.

  Specifically, the database 141 according to the present embodiment includes a well-known Neugebauer (Neugebauer) that defines the correspondence between the halftone dot area ratio of each ink color and the mixed color halftone density as shown in the following formula (1). The expression itself is stored.

Further, in the present embodiment, before performing the final printing of the printed matter on the printing machine (actual machine), the solids of k, c, m, and y (also referred to as solid density values) in advance on the printing machine, kc, km, ky, cm, cy, my that superimposes any two colors of k, c, m, and y, and kcm that superimposes any three colors of these solid k, c, m, and y , Kcy, kmy, cmy, and kcmy obtained by superimposing these four solid colors k, c, m, y (see FIG. 6), and the printed color chart Each density value Dk (λ) corresponding to solid k, c, m, y, kc, km, ky, cm, cy, my, kcm, kcy, kmy, cmy, kmy by actual measurement with the IRGB densitometer 1 , Dc (λ), Dm (λ), Dy (λ), Dkc (λ), D km (λ), Dky (λ), Dcm (λ), Dcy (λ), Dmy (λ), Dkcm (λ), Dkcy (λ), Dkmy (λ), Dcmy (λ), Dkcmy (λ) The values of these density values Dk (λ) to Dkcmy (λ) are substituted into the Neugebauer equation. Then, the actual mixed color halftone densities I, R, G, and B calculated in step S30 are substituted into the Neugebauer equation Dao (λ), respectively, and the four-dimensional simultaneous nonlinear equations are solved to obtain the actual mixed color halftone densities I, R, and G. , B, the real dot area ratios k, c, m, y of the respective ink colors are obtained. In this manner, the actual halftone dot area ratio can be easily obtained from the actual mixed color halftone density by calculation. Further, as in this embodiment, k, c, m, and y solids and k, c, m, and y solids kc, km, ky, cm, cy, my, kcm, kcy, and kmy are superimposed. , Cmy, and kcmy are constructed by substituting the solid density value previously obtained by using the IRGB densitometer 1 into the Neugebauer equation, thereby creating an actual halftone dot area in the color space corresponding to the solid density value. If the blank area is soiled, that is, if ink is attached, the actual mixed color halftone density value becomes greater than 0, and the actual halftone dot area ratios k, c, m, Any one or more of y is greater than zero. Therefore, in step S50, the stain determination unit 15 determines whether or not the actual halftone dot area ratios k, c, m, and y of each ink color are greater than a preset threshold (or greater than or equal to a threshold). If the real dot area ratios k, c, m, and y are larger than the threshold value, it is determined that the ink is stained. At this time, it is also determined whether the dampening water adjustment zone (the left nozzle group 74L zone or the right nozzle group 74R zone) is contaminated.

Here, it is possible to identify even lighter stains as the threshold values for the actual halftone dot area ratios k, c, m, and y are reduced. However, the calculation error of converting from the actual mixed color halftone density to the actual halftone dot area ratio is not limited. For this reason, if the threshold value is increased too much, the determination accuracy of ink stains is lowered. Therefore, it is preferable to set the threshold value in consideration of these. The threshold is basically common to each color.
In step S60, the dampening water amount setting unit 16 increases and corrects the dampening water supply amount Qw based on the determination result determined by the dirt determination unit 15. That is, with respect to the dampening water supply device 70 of the ink printing unit that has been determined to be dirty by the stain determination unit 15, the humidity in the corresponding adjustment zone (the zone of the left nozzle group 74L or the zone of the right nozzle group 74R). The water supply amount Qw is increased from the current state by a predetermined amount (a constant amount) ΔQw. Specifically, the dampening water injection amount from the nozzle (injection amount per unit time) is set to increase by a predetermined amount.

However, if the dampening water supply amount Qw becomes excessive, problems such as floating dirt and roller stripping phenomenon are caused. Therefore, the dampening water supply amount has an upper limit value QwMAX, and the dampening water amount setting unit 16
If the dampening water supply amount Qw is increased by a predetermined amount and the upper limit value is exceeded, the dampening water supply amount Qw is set to clip at this upper limit value QwMAX.
Based on the corrected dampening water supply amount Qw transmitted from the dampening water amount setting unit 16 of the arithmetic unit 10, the control device 20 of the printing press uses the water from the nozzle of the water spray device 74 of the dampening water supply device 70. The injection amount is controlled to increase on the basis of each adjustment zone.

  After the increase control of the dampening water supply amount, the control device 20 of the printing press starts counting the number of printed sheets from the time when the increase control is performed (step S70), and the number of printed sheets N is a predetermined number N1 (for example, 100 to several). It is set so that the state is maintained (that is, the dampening water supply amount is not changed) through the determination in step S80 until it reaches about 100 sheets). This is because even if the dampening water supply amount is adjusted, it takes time to eliminate ink stains. After confirming the correction result of the dampening water supply amount, Supply amount control is performed.

Since the ground detection method and apparatus for printed matter and the control method and apparatus for a printing press according to the first embodiment of the present invention are configured as described above, if there is ground stain (ink stain) on the printed matter, a plurality of ground stains (ink stains) are present. Even in the case where stains with overlapping inks occur, it is possible to easily and reliably determine which ink stains.
Further, since the stain is detected by paying attention to the non-image area (that is, the blank area) of the printed matter, the detection accuracy is high. In particular, the measurement area 53 is set by excluding a portion within a predetermined distance adjacent to the image line portion in the blank area of the printed matter, and the actual mixed color halftone density is measured to determine the stain for each ink color. Accordingly, it is possible to prevent a problem that an adjacent image line portion is erroneously determined to be dirty.

Then, according to the determination result, the control of the supply amount of the dampening water of the corresponding ink unit is performed to prevent the occurrence of ink stains. Since the dampening water supply amount is adjusted by appropriately determining whether or not the printing unit is in the dampening water supply amount state in which the soiling occurs, the generation of the soiling can be surely prevented.
In addition, if the amount of dampening water supplied becomes excessive, overemulsification will result in problems such as floating stains and roller stripping, but an upper limit is set for the dampening water supply amount to compensate for the increase in dampening water amount. Since this is done, such a problem can be avoided.

Furthermore, it takes time for this effect to appear after increasing the supply amount of dampening water. However, after a predetermined number of prints have been made, that is, after the effect of increasing the dampening water supply amount appears, Since dirt detection is performed, appropriate feedback control can be performed without increasing the dampening water supply amount excessively.
(B) Second Embodiment Next, a newspaper offset rotary press according to a second embodiment of the present invention will be described. This embodiment is different in the process in step S40 (halftone dot area ratio calculating step) described in the first embodiment. That is, in the first embodiment described above, each density value Dk (λ) to Dkcmy (λ) is obtained by actually measuring a solid color chart with the IRGB densitometer 1, and each of these density values Dk (λ) to Dkcmy ( λ) is substituted into the Neugebauer equation, but in this embodiment, a color chart of a halftone dot (a halftone dot area ratio smaller than a solid, and a halftone dot area ratio of 25% will be described as an example here) is not solid. The density values Dk (λ) to Dkcmy (λ) are obtained by actual measurement with the IRGB densitometer 1, and these density values Dk (λ) to Dkcmy (λ) are substituted into the Neugebauer equation.

  Specifically, in the present embodiment, before the actual printing of the printed matter with the printing machine (actual machine), the k, c, m, and y nets (or the net density values are also called with the printing machine in advance. A dot area ratio of 25%), kc, km, ky, cm, cy, my obtained by superimposing any two colors of k, c, m, and y of these meshes, and k, c of these meshes , M, and y, and a color chart composed of kcm, kcy, kmy, and cmy, and kcmy that overlays all four colors of k, c, m, and y of these meshes. The printed color chart is actually measured with the IRGB densitometer 1 to obtain k, c, m, y, kc, km, ky, cm, cy, my, kcm, kcy, kmy, cmy, and kcmy of the net. Corresponding density values Dk (λ), Dc (λ), Dm (λ), Dy (λ), D c (λ), Dkm (λ), Dky (λ), Dcm (λ), Dcy (λ), Dmy (λ), Dkcm (λ), Dkcy (λ), Dkmy (λ), Dcmy (λ), Dkcmy (λ) is obtained, and values of these density values Dk (λ) to Dkcmy (λ) are substituted into the Neugebauer equation. Then, the actual mixed color halftone densities I, R, G, and B calculated in step S30 are substituted into the Neugebauer equation Dao (λ), respectively, and the four-dimensional simultaneous nonlinear equations are solved to obtain the actual mixed color halftone densities I, R, and G. , B, the real dot area ratios k, c, m, y of the respective ink colors are obtained. In this manner, the actual halftone dot area ratio can be easily obtained from the actual mixed color halftone density by calculation. Further, as in the present embodiment, k, c, m, y nets and kc, km, ky, cm, cy, my, kcm, kcy, kmy obtained by superimposing these k, c, m, y nets. By constructing a color chart composed of, cmy, and kcmy by previously substituting the halftone density value previously obtained using the IRGB densitometer 1 into the Neugebauer equation, the actual halftone dot area in the color space corresponding to the halftone density value The rate can be calculated.

However, when the Neugebauer formula is constructed using a halftone dot color chart of 25%, for example, as in this embodiment, the Neugebauer formula is constructed using a solid color chart as in the first embodiment described above. In this embodiment, the halftone dot area ratios k, c, m, and y are finally multiplied by ¼.
In the subsequent processing, as in the first embodiment, the stain determination unit 15 determines that the actual halftone dot area ratios k, c, m, and y of each ink color are greater than a preset threshold (or greater than or equal to the threshold). And if there is an actual dot area ratio k, c, m, y greater than the threshold value, it is determined that the ink is soiled, and the dampening water amount setting unit 16 Based on the determination result determined by the dirt determination unit 15, the dampening water supply amount Qw is increased and corrected.

  According to this embodiment, the same effect as that of the first embodiment can be obtained. In addition, it is possible to increase the sensitivity of background detection as compared with the first embodiment. That is, the actual halftone dot area ratio can be calculated in a color space smaller than the color space corresponding to the solid density value described in the first embodiment. In this embodiment, the detection sensitivity is the detection sensitivity of the first embodiment. Therefore, thinner ground dirt can be detected. In the first embodiment, if the threshold value is set low, it is possible to detect even when the background stain is very thin. However, when the threshold value is set to, for example, 1% of the halftone dot area ratio, the density conversion is about 0. .05D (Density), which is a very small value. In this case, such small changes in density may not be detected accurately or the detection error may increase. It is also possible to increase it. On the other hand, in this embodiment, instead of setting the threshold value low, it is possible to prevent erroneous detection by constructing the Neugebauer equation using a halftone dot area color chart that is smaller than a solid in advance. At the same time, it is possible to accurately detect even a thin background.

  In the present embodiment, the Neugebauer equation is constructed using a halftone dot color chart having a halftone dot area ratio of 25%. However, the color chart may be a halftone dot area ratio having a value smaller than a solid, and a desired detection sensitivity. The Neugebauer equation may be constructed using a halftone dot color chart with an appropriate halftone dot area ratio. For example, when the Neugebauer formula is constructed using a halftone dot color chart of 50%, the detection sensitivity is doubled compared to the first embodiment, and the halftone dot area percentage is 10%. When the Neugebauer equation is constructed using the chart, the detection sensitivity is 10 times that of the first embodiment.

(C) Third Embodiment Next, a newspaper offset rotary press according to a third embodiment of the present invention will be described. This embodiment is different in the process in step S40 (halftone dot area ratio calculating step) described in the first embodiment. That is, the Neugebauer equation is stored in the database 141 according to the first embodiment described above, but the database 141 according to the present embodiment stores the well-known Yule-Nielsen (Yule-Nielsen) as shown in the following equation (2). The extended Neugebauer equation that incorporates the equation ()) is stored.

The other symbols in the formula (2) are the same as those in the formula (1) of the first embodiment, and will be omitted.
Further, in the present embodiment, as in the first embodiment, before the actual printing of the printed matter is performed by the printing machine (actual machine), each solid (or solid density value) of k, c, m, and y is previously determined by the printing machine. And kc, km, ky, cm, cy, my, and any of these solid k, c, m, y. Print a color chart (see Fig. 6) consisting of kcm, kcy, kmy, cmy with these three colors superimposed, and kcmy with these four solid colors k, c, m, y superimposed The printed color chart is actually measured with the IRGB densitometer 1 to correspond to solid k, c, m, y, kc, km, ky, cm, cy, my, kcm, kcy, kmy, cmy, kmy. Concentration values Dk (λ), Dc (λ), Dm (λ), Dy λ), Dkc (λ), Dkm (λ), Dky (λ), Dcm (λ), Dcy (λ), Dmy (λ), Dkcm (λ), Dkcy (λ), Dkmy (λ), Dcmy ( λ) and Dkcmy (λ) are obtained, and the values of these density values Dk (λ) to Dkcmy (λ) are substituted into the extended Neugebauer equation. Then, the actual mixed color halftone densities I, R, G, and B calculated in step S30 are respectively substituted into the extended Neugebauer equation Dao (λ), and n is, for example, the relationship between the halftone dot area ratio and the mixed color halftone density value. Substituting a value such that is substantially linear, and solving the four-dimensional simultaneous nonlinear equations, the actual halftone dot area ratios k, c, m of the respective ink colors corresponding to the actual mixed color halftone densities I, R, G, B , Y is obtained. In this manner, the actual halftone dot area ratio can be easily obtained from the actual mixed color halftone density by calculation. In addition, as in the present embodiment, the extended Neugebauer equation has k, c, m, y solids and kc, km, ky, cm, cy, my, If a color chart composed of kcm, kcy, kmy, cmy, and kcmy is constructed by preliminarily substituting the solid density value obtained using the IRGB densitometer 1, the color chart is realized in the color space corresponding to the solid density value. The dot area ratio can be calculated.

  In the subsequent processing, as in the first embodiment, the stain determination unit 15 determines that the actual halftone dot area ratios k, c, m, and y of each ink color are greater than a preset threshold (or greater than or equal to the threshold). And if there is an actual dot area ratio k, c, m, y greater than the threshold value, it is determined that the ink is soiled, and the dampening water amount setting unit 16 Based on the determination result determined by the dirt determination unit 15, the dampening water supply amount Qw is increased and corrected.

  According to this embodiment, the same effect as that of the first embodiment can be obtained. Further, when the Neugebauer equation is constructed using a solid color chart as in the first embodiment, and a dark background stain occurs, the Neugebauer equation is obtained when the halftone dot area ratio obtained by calculation reaches 100% or more. However, in this embodiment, since the extended Neugebauer equation, which incorporates the Yule-Nielsen equation in the Neugebauer equation, is used, there is a risk of dark soiling. If it occurs, there is a solution of the four-dimensional simultaneous nonlinear equation even if the halftone dot area ratio obtained by the calculation is 100% or more, and an accurate real halftone dot area ratio can be calculated.

(D) Fourth Embodiment Next, a newspaper offset rotary press according to a fourth embodiment of the present invention will be described. This embodiment is different in the process in step S40 (halftone dot area ratio calculating step) described in the first embodiment. That is, the Neugebauer equation is stored in the database 141 according to the first embodiment described above, but the database 141 according to the present embodiment has the equation (2) as in the third embodiment described above. An extended Neugebauer equation that incorporates the well-known Yule-Nielsen equation is stored.

Further, in the present embodiment, the IRGB densitometer 1 actually measures a color chart of a net (a halftone dot area ratio smaller than a solid, and a halftone dot area ratio of 25% will be described as an example here) instead of a solid. Thus, the respective density values Dk (λ) to Dkcmy (λ) are obtained and these density values Dk (λ) to Dkcmy (λ) are substituted into the extended Neugebauer equation.
Specifically, in the present embodiment, before the actual printing of the printed matter with the printing machine (actual machine), the k, c, m, and y nets (or the net density values are also called with the printing machine in advance. A dot area ratio of 25%), kc, km, ky, cm, cy, my obtained by superimposing any two colors of k, c, m, and y of these meshes, and k, c of these meshes , M, and y, and a color chart composed of kcm, kcy, kmy, and cmy, and kcmy that overlays all four colors of k, c, m, and y of these meshes. The printed color chart is actually measured with the IRGB densitometer 1 to obtain k, c, m, y, kc, km, ky, cm, cy, my, kcm, kcy, kmy, cmy, and kcmy of the net. Corresponding density values Dk (λ), Dc (λ), Dm (λ), Dy (λ), D c (λ), Dkm (λ), Dky (λ), Dcm (λ), Dcy (λ), Dmy (λ), Dkcm (λ), Dkcy (λ), Dkmy (λ), Dcmy (λ), Dkcmy (λ) is obtained, and values of these density values Dk (λ) to Dkcmy (λ) are substituted into the extended Neugebauer equation. Then, the actual mixed color halftone densities I, R, G, and B calculated in step S30 are respectively substituted into the extended Neugebauer equation Dao (λ), and for the coefficient n, for example, the halftone dot area ratio and the mixed color halftone density value. By substituting values such that the relationship is almost linear, and solving the four-dimensional simultaneous nonlinear equations, the actual halftone dot area ratios k, c, and k of the respective ink colors corresponding to the actual mixed color halftone densities I, R, G, B m and y are obtained. In this manner, the actual halftone dot area ratio can be easily obtained from the actual mixed color halftone density by calculation. Further, as in the present embodiment, k, c, m, y nets and kc, km, ky, cm, cy, my, kcm, kcy, kmy obtained by superimposing these k, c, m, y nets. , Cmy, and kcmy are constructed by substituting the halftone density value previously obtained by using the IRGB densitometer 1 into the extended Neugebauer equation, thereby creating a real halftone dot in the color space corresponding to the halftone value. The area ratio can be calculated.

However, when the extended Neugebauer equation is constructed using a halftone dot color chart of 25%, for example, as in the present embodiment, the Neugebauer equation is constructed using a solid color chart as in the first embodiment. Since the halftone dot area ratio that is four times that at the time of construction is calculated, in the present embodiment, the calculated halftone dot area ratios k, c, m, and y are finally multiplied by ¼.
In the subsequent processing, as in the first embodiment, the stain determination unit 15 determines that the actual halftone dot area ratios k, c, m, and y of each ink color are greater than a preset threshold (or greater than or equal to the threshold). And if there is an actual dot area ratio k, c, m, y greater than the threshold value, it is determined that the ink is soiled, and the dampening water amount setting unit 16 Based on the determination result determined by the dirt determination unit 15, the dampening water supply amount Qw is increased and corrected.

  According to this embodiment, the same effect as that of the first embodiment can be obtained. In addition, it is possible to increase the sensitivity of background detection as compared with the first embodiment. That is, the actual halftone dot area ratio can be calculated in a color space smaller than the color space corresponding to the solid density value described in the first embodiment. In this embodiment, the detection sensitivity is the detection sensitivity of the first embodiment. Therefore, thinner ground dirt can be detected. In the first embodiment, if the threshold value is set low, it is possible to detect even when the background stain is very thin. However, when the threshold value is set to, for example, 1% of the halftone dot area ratio, the density conversion is about 0. .05D (Density), which is a very small value. In this case, such small changes in density may not be detected accurately or the detection error may increase. It is also possible to increase it. On the other hand, in this embodiment, instead of setting the threshold value low, it is possible to prevent false detection by constructing an extended Neugebauer equation using a halftone dot area color chart smaller than solid in advance. At the same time, it becomes possible to accurately detect even a thin background.

Moreover, even if the Neugebauer equation of the first embodiment is constructed using the color chart of the halftone dot area ratio of 25% described in this embodiment (that is, the second embodiment), the thin background dirt is accurately obtained. In contrast, if dark soiling occurs, if the halftone dot area ratio calculated by calculation is 100% or more, the right side of the Neugebauer equation becomes a negative value and there is a solution for the four-dimensional simultaneous nonlinear equation. In this embodiment, since the extended Neugebauer equation, which incorporates the Yule-Nielsen equation, is used in the Neugebauer equation, the dot area ratio calculated by the calculation is 100% or more when dark background soiling occurs. Even so, there is a solution of a four-dimensional simultaneous nonlinear equation, and an accurate halftone dot area ratio can be calculated. In this embodiment, a halftone dot color ratio of 25% is used. Although the extended Neugebauer equation was constructed using a color chart, the color chart may be a halftone dot area ratio that is smaller than a solid value, and a halftone dot area ratio color chart corresponding to the desired detection sensitivity Use it to construct an extended Neugebauer equation. For example, when the extended Neugebauer equation is constructed using a color chart of a halftone dot area ratio of 10%, the detection sensitivity is 10 times that of the first embodiment, and the halftone dot area ratio is 50%. When the extended Neugebauer equation is constructed using the color chart, the detection sensitivity is doubled compared to the first embodiment.
(E) Others Although the embodiment of the present invention has been described above, the embodiment of the present invention is not limited to the above.

For example, in the above-described embodiment, the dampening water supply zone is divided into two on the left and right, but more may be divided, and in this case, the amount of dampening water can be adjusted more closely. Alternatively, even if the dampening water supply zone is not divided and the dampening water amount is controlled roughly for each printing unit, the control accuracy is not high, but simpler control is achieved.
Furthermore, the fountain solution supply device is not limited to the type of the above embodiment.

Further, if attention is paid to the method and apparatus for detecting soil on printed matter, the present invention is not limited to the increase control of the fountain solution, but can also be used for control of other countermeasures for soiling.
Further, in the above embodiment, when the contamination is determined, the dampening water supply amount is increased by a certain amount. However, the increase correction amount of the dampening water supply amount is changed according to the degree of contamination. Also good. That is, the actual halftone dot area ratios k, c, m, y can be used as parameters for the degree of contamination, and the larger the real halftone dot area ratios k, c, m, y calculated by the color conversion unit 14 are. Increase the amount of increase correction (however, within the upper limit) and increase the amount of dampening water. In this case, there is a possibility that the background dirt can be eliminated more quickly.

In the above embodiment, a line sensor type IRGB densitometer is used, but a spot type IRGB densitometer may be used to scan the print sheet two-dimensionally.
In the above embodiment, a color chart printed at a predetermined halftone dot area ratio (for example, solid in the first and third embodiments and 25% in the second and fourth embodiments) is used. You may use the color chart printed using the data of the newspaper printing Japan Color (ISO12642) which the TC130 national committee established. Since the data for newspaper printing Japan Color (ISO12642) contains data relating to solid and a plurality of halftone dot area ratios, if this newspaper printing Japan Color (ISO12642) data is used, the halftone dot area ratio starts from 0%. A plurality of color charts up to 100% (for example, 10%, 20%, etc., and 10% color charts) can be created at a time. If such a color chart is measured once with the IRGB densitometer 1, the respective density values Dk (λ) to Dkcmy (λ) corresponding to each of the plurality of halftone dot area ratios can be obtained. Thereby, a conversion table (also referred to as LUT: Look Up Table) that defines the correspondence between each dot area ratio and each of the density values Dk (λ) to Dkcmy (λ) can be obtained. Therefore, if this conversion table is stored in the database 141, the density values Dk (λ) to Dkcmy (λ) corresponding to the desired halftone dot area ratio are appropriately selected and substituted into the Neugebauer equation or the extended Neugebauer equation. Therefore, it is not necessary to print a color chart and measure with an IRGB densitometer every time printed matter is printed, and the preprocessing time for detecting soiling can be shortened. That is, it is possible to more easily detect scumming.

  Furthermore, depending on the customer, the standard to be regarded as “dirt” may be different. In this case, the actual stain on the printed matter pointed out by the customer is measured with an IRGB densitometer and the mixed color network of the stain is obtained. Densities I, R, G, and B are obtained, and the mixed color halftone densities I, R, G, and B are substituted into a Neugebauer equation or an extended Neugebauer equation constructed with a solid or halftone dot, and a halftone dot area ratio k, c, m, It is only necessary to obtain y and set the halftone dot area ratios k, c, m, and y as threshold values. In this way, it is possible to detect scumming according to the customer's standards for scumming.

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows schematic structure of the newspaper offset rotary press concerning 1st Embodiment of this invention. It is a schematic diagram which shows the dampening water supply amount adjusting device concerning 1st Embodiment of this invention. It is a functional block diagram which paid its attention to the dampening water supply amount control of the arithmetic unit concerning 1st Embodiment of this invention. It is a schematic diagram of the platemaking image explaining the background contamination detection according to the first embodiment of the present invention. It is a flowchart which shows the processing flow of the background detection and the dampening water supply amount control concerning 1st Embodiment of this invention. It is a schematic diagram which shows the color chart concerning 1st Embodiment of this invention. It is a schematic diagram of a printed image explaining the subject concerning this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Line sensor type IRGB densitometer 2a, 2b, 2c, 2d Printing unit 3 Blanket cylinder 4 Plate cylinder 5 Ink roller group 6 Ink roller 7 Ink key 8 Printing sheet 9 Inking roller 10 Arithmetic unit 11 DSP
12 PC
14 Color conversion unit 15 Stain determination unit 16 Dampening water amount setting unit 20 Control device built in printing press 30 Touch panel 70 Dampening water supply device 74 Water spray device

Claims (26)

Using an IRGB densitometer, an actual mixed-color halftone density measuring step for measuring an actual mixed-color halftone density of ink stains in a non-image area of a printed matter;
An actual halftone dot area ratio calculating step for obtaining an actual halftone dot area ratio of each ink color corresponding to the actual mixed color halftone density, based on a correspondence relationship between a predetermined halftone dot area ratio and the mixed color halftone density;
The actual halftone dot area ratio of each ink color is compared with a preset threshold value, and if there is an ink color with the actual halftone dot area ratio exceeding the threshold value, the ink color stain exceeding the threshold value A stain detection method for printed matter, comprising: a stain determination step for determining that there is an image. In the actual mixed color halftone density measuring step, a measurement area is set by excluding a portion within a predetermined distance adjacent to the image line portion of the printed material among the non-image line portions of the printed material, and the measurement area is set with respect to the measurement area. 2. The method for detecting a background stain of a printed matter according to claim 1, wherein an actual mixed color halftone density is measured. The correspondence between the halftone dot area ratio and the mixed color halftone density is a correspondence defined by the Neugebauer equation,
In the actual halftone dot area ratio calculating step, by substituting the actual mixed color halftone density measured in the actual mixed color halftone density measuring step into the Neugebauer equation, the actual halftone dot of each ink color corresponding to the actual mixed color halftone density 3. A method for detecting a background stain of a printed matter according to claim 1, wherein an area ratio is obtained. The Neugebauer formula is a solid of k, c, m, y and kc, km, ky, cm, cy, my, kcm, kcy, kmy, cmy, kcmy obtained by superimposing these k, c, m, y solids. 4. A method for detecting background smudges in a printed matter according to claim 3, wherein a solid density value previously obtained by using the IRGB densitometer is substituted into the color chart constituted by The Neugebauer equations are k, c, m, y nets and kc, km, ky, cm, cy, my, kcm, kcy, kmy, cmy, kmy, which are obtained by superimposing these k, c, m, y nets. 4. The method for detecting a background stain on a printed matter according to claim 3, wherein the color chart constructed from the above is constructed by substituting the halftone density value previously obtained by using the IRGB densitometer. The correspondence relationship between the halftone dot area ratio and the mixed color halftone density is a correspondence relationship defined by the extended Neugebauer equation in which the Yule-Nielsen equation is incorporated in the Neugebauer equation,
In the actual halftone dot area ratio calculating step, the actual mixed color halftone density measured in the actual mixed color halftone density measuring step is substituted into the extended Neugebauer equation, so that the actual net of each ink color corresponding to the actual mixed color halftone density is obtained. 3. The method for detecting a background stain of a printed matter according to claim 1, wherein a dot area ratio is obtained. The extended Neugebauer equation is a solid of k, c, m, y and kc, km, ky, cm, cy, my, kcm, kcy, kmy, cmy, which is a solid of these k, c, m, y. 7. The method for detecting a background stain on a printed matter according to claim 6, wherein a color chart composed of kcmy is constructed by previously substituting a solid density value obtained by using the IRGB densitometer. The extended Neugebauer equation is expressed as k, c, m, y, and kc, km, ky, cm, cy, my, kcm, kcy, kmy, cmy, which are obtained by superimposing these k, c, m, y nets. 7. A method for detecting a background stain on a printed matter according to claim 6, wherein a color chart composed of kcmy is constructed by previously substituting a density value obtained by using the IRGB densitometer. Each step according to any one of claims 1 to 8,
When it is determined whether there is any ink-colored background stain on the printed matter, the dampening water supply means of the printing unit of the corresponding ink color is controlled to adjust the amount of dampening water supplied to the background-stain suppression side. A control method for a printing press, comprising a water supply amount adjustment step. The dampening water supply means is capable of adjusting the dampening water supply amount in units of a plurality of areas divided in the axial direction of the printing cylinder,
In the actual halftone dot area ratio calculating step, the actual halftone dot area ratio of each ink color is obtained for each area corresponding to the area unit,
In the stain determination step, the stain of each ink color is determined for each area corresponding to the area unit,
10. The control method for a printing press according to claim 9, wherein in the dampening water supply amount adjusting step, the dampening water supply amount is adjusted in units of the areas. 11. The control method for a printing press according to claim 9 or 10, wherein, in the dampening water supply amount adjusting step, when ink stain is determined, the dampening water supply amount is increased by a predetermined amount. 12. The dampening water supply amount is set to an upper limit value, and the dampening water supply amount adjustment step performs increase control of the dampening water supply amount within the upper limit value. Control method of printing press. 13. The stain determination step is performed after the dampening water supply amount adjusting step is performed once, after waiting for printing for a preset number of sheets. The control method of the printing machine of any one of Claims 1. An IRGB densitometer arranged on a running line of a printing sheet obtained by printing;
A color mixture halftone density measuring means for operating the IRGB densitometer to measure the actual color mixture halftone density of the printing sheet;
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 a correspondence relationship between a predetermined halftone dot area ratio and the mixed color halftone density;
The actual halftone dot area ratio of each ink color is compared with a preset threshold value. If there is an ink color whose actual halftone dot area ratio exceeds the threshold value, the ink color stain exceeding the threshold value is stained. A ground contamination detection device for printed matter, characterized by comprising stain determination means for determining that there is a printed matter. In the mixed color halftone density measuring means, a measurement area is set by excluding a portion within a predetermined distance adjacent to the image line portion of the printed material among the non-image area of the printed material, and the actual area is measured with respect to the measurement area. 15. The background detection device for printed matter according to claim 14, wherein the mixed color halftone density is measured. The correspondence between the halftone dot area ratio and the mixed color halftone density is a correspondence defined by the Neugebauer equation,
The actual halftone dot area ratio calculating means substitutes the actual mixed color halftone density measured by the mixed color halftone density measuring means into the Neugebauer equation, so that the actual halftone dot area of each ink color corresponding to the actual mixed color halftone density is obtained. The ground detection device for printed matter according to claim 14 or 15, wherein a rate is obtained. The Neugebauer formula is a solid of k, c, m, y and kc, km, ky, cm, cy, my, kcm, kcy, kmy, cmy, kcmy obtained by superimposing these k, c, m, y solids. 17. The background detection device for printed matter according to claim 16, wherein a solid density value obtained by using the IRGB densitometer in advance is substituted for the color chart constituted by: The Neugebauer equations are k, c, m, y nets and kc, km, ky, cm, cy, my, kcm, kcy, kmy, cmy, kmy, which are obtained by superimposing these k, c, m, y nets. 17. The apparatus according to claim 16, wherein the color chart constructed from the above is constructed by previously substituting the halftone density value previously obtained by using the IRGB densitometer. The correspondence relationship between the halftone dot area ratio and the mixed color halftone density is a correspondence relationship defined by the extended Neugebauer equation in which the Yule-Nielsen equation is incorporated in the Neugebauer equation,
The actual halftone dot area ratio calculating means substitutes the actual mixed color halftone density measured by the actual mixed color halftone density measuring means into the extended Neugebauer equation, so that the actual net of each ink color corresponding to the actual mixed color halftone density is obtained. 16. The background contamination detection apparatus for printed matter according to claim 14, wherein a point area ratio is obtained. The extended Neugebauer equation is a solid of k, c, m, y and kc, km, ky, cm, cy, my, kcm, kcy, kmy, cmy, which is a solid of these k, c, m, y. 20. The background detection device for printed matter according to claim 19, wherein a color chart composed of kcmy is constructed by previously substituting a solid density value obtained by using the IRGB densitometer. The extended Neugebauer equation is expressed as k, c, m, y, and kc, km, ky, cm, cy, my, kcm, kcy, kmy, cmy, which are obtained by superimposing these k, c, m, y nets. 20. The background detection device for printed matter according to claim 19, wherein a color chart composed of kcmy is constructed by substituting a density value obtained in advance using the IRGB densitometer. The ground detection device for printed matter according to any one of claims 14 to 21,
A dampening water supply means capable of adjusting a dampening water supply amount to be supplied to the printing cylinder;
When it is determined by the background stain detection device whether there is any ink color background stain on the printed matter, the dampening water supply amount of the printing unit of the corresponding ink color is dampened so as to be on the background side. And a control unit for controlling the water supply unit. The dampening water supply means is capable of adjusting the dampening water supply amount in units of a plurality of areas divided in the axial direction of the printing cylinder,
In the real halftone dot area rate calculating means, the real halftone dot area rate of each ink color is obtained for each region according to the area unit,
The stain determination means determines the stain of each ink color for each area according to the area unit,
23. The control device for a printing press according to claim 22, wherein the control means adjusts the dampening water supply amount in the area unit with respect to the dampening water supply device.   24. The control device for a printing press according to claim 22 or 23, wherein said control means increases the supply amount of dampening water by a predetermined amount when ink contamination is determined. 25. The control device for a printing press according to claim 24, wherein an upper limit value is set for the dampening water supply amount, and the control means performs an increase control of the dampening water supply amount within the upper limit value. . After the dampening water supply amount adjusting unit once adjusts the dampening water supply amount, the stain determination unit performs the stain determination after waiting for printing for a preset number of sheets. The control device for a printing press according to any one of claims 22 to 25, characterized in that:

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