Method of feeding dampening water in a printing machine
AssigneeDainippon Screen Mfg. Co., Ltd.
InventorsTakaharu Yamamoto, Nobuhito Kohara, Satoru Kiyohara
Life of this patent
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Abstract
A method of feeding dampening water includes a density measuring step for measuring densities of first and second detecting patches 101 and 102 printed adjacent each other on printed matter 100 and presenting a difference in density variations after printing with varied feed rates of damping water and ink, a dampening water feeding step for controlling the feed rate of dampening water based on the densities of the first and second detecting patches 101 and 102 measured in the density measuring step, and an ink feeding step for controlling the feed rate of ink based on the densities of the first and second detecting patches measured in the density measuring step, and the feed rate of dampening water.
Claims16
A method of feeding dampening water in a printing machine for controlling a feed rate of dampening water along with a feed rate of ink by using a plurality of first and second detecting patches printed adjacent each other on printed matter and presenting a difference in density variations after printing with varied feed rates of damping water and ink, said method comprising:
- a density measuring step for measuring densities of said first and second detecting patches;
- a dampening water feeding step for controlling the feed rate of dampening water based on the densities of said first and second detecting patches measured in said density measuring step;
- and
- an ink feeding step for controlling the feed rate of ink based on the densities of said first and second detecting patches measured in said density measuring step, and said feed rate of dampening water determined in said dampening water feeding step.
A method of feeding dampening water in a printing machine for controlling a feed rate of dampening water along with a feed rate of ink by using two types of detecting patches printed adjacent each other in areas and arranged in a direction of width of printed matter and presenting a difference in density variations after printing with varied feed rates of damping water and ink;
- wherein one of said two types of detecting patches has a large halftone area ratio and comprises first detecting patches, while the other of said two types of detecting patches has a small halftone area ratio and comprises second detecting patches;
- said method comprising:
- a critical density measuring step for measuring a critical density DM at which a shortage of dampening water causes a defective print, from prints obtained by performing printing a plurality of times while varying the feed rate of dampening water;
- a preparatory density measuring step for measuring a density D1x of said first detecting patches and a density D2x of said second detecting patches from each of prints obtained by performing printing a plurality of times while varying the feed rate of ink;
- a multiple linear regression step for deriving coefficients a, b and c from an equation (1) set out below and representing a parameter Dwx, by multiple linear regression, using the critical density DM measured in said critical density measuring step, and the density D1x of said first detecting patches and the density D2x of said second detecting patches measured in said preparatory density measuring step in time of each printing;
- a density measuring step for measuring a density D1x of each of said first detecting patches and a density D2x of each of said second detecting patches arranged in said areas, from printed matter obtained by trial printing;
- a parameter computing step for computing the parameter Dwx for each of said areas, by using the equation (1) set out below, from the coefficients a, b and c obtained in said multiple linear regression step, and the density D1x of each of said first detecting patches and the density D2x of each of said second detecting patches obtained in said density measuring step;
- a dampening water feed rate adjusting step for adjusting the feed rate of dampening water based on a minimum parameter minDwx of parameters Dwx for said areas obtained in said parameter computing step;
- an adjusted ink feed rate computing step for computing an adjusted ink feed rate a for each of said areas, by using an equation (2) set out below and representing the adjusted ink feed rate α, from a target density DT, the critical density DM obtained in said critical density measuring step, the parameter Dwx for each of said areas obtained in said parameter computing step, and the minimum parameter minDwx of parameters Dwx for said areas obtained in said parameter computing step;
- and
- an ink feed rate adjusting step for adjusting the feed rate of ink for each of said areas based on the adjusted ink feed rate α obtained in said adjusted ink feed rate computing step:
- Dwx=DM−D1x=a·D1x+b·D2x+c (1)
- α=DT−DM+(Dwx−minDwx) (2).
A method of feeding dampening water in a printing machine for controlling a feed rate of dampening water along with a feed rate of ink by using three types of detecting patches printed adjacent one another in areas, arranged in a direction of width of printed matter and presenting differences in density variations after printing with varied feed rates of damping water and ink;
- wherein one of said three types of detecting patches has a large halftone area ratio and comprises first detecting patches, another of said three types of detecting patches has a smaller halftone area ratio than said first detecting patches and comprises second detecting patches, and the remaining type of detecting patches has a smaller halftone area ratio than said first detecting patches and a different resolution to said second detecting patches and comprise third detecting patches;
- said method comprising:
- a critical density measuring step for measuring a critical density DM at which a shortage of dampening water causes a defective print, from prints obtained by performing printing a plurality of times while varying the feed rate of dampening water;
- a preparatory density measuring step for measuring a density D1x of said first detecting patches, a density D2x of said second detecting patches a density D3x of said third detecting patches from each of prints obtained by performing printing a plurality of times while varying the feed rate of ink;
- a multiple linear regression step for deriving coefficients d, e, f and g from an equation (3) set out below and representing a parameter Dwx, by multiple linear regression, using the critical density DM measured in said critical density measuring step, and the density D1x of said first detecting patches, the density D2x of said second detecting patches and the density D3x of said third detecting patches measured in said preparatory density measuring step in time of each printing;
- a density measuring step for measuring a density D1x of each of said first detecting patches, a density D2x of each of said second detecting patches and a density D3x of each of said third detecting patches arranged in said areas, from printed matter obtained by trial printing;
- a parameter computing step for computing the parameter Dwx, by using the equation (3) set out below, from the coefficients d, e, f and g obtained in said multiple linear regression step, and the density D1x of each of said first detecting patches, the density D2x of each of said second detecting patches and the density D3x of each of said third detecting patches obtained in said density measuring step;
- a dampening water feed rate adjusting step for adjusting the feed rate of dampening water based on the parameters Dwx obtained in said parameter computing step;
- and
- an ink feed rate adjusting step for adjusting the feed rate of ink based on a target density DT, and the parameter Dwx obtained in said parameter computing step:
- Dwx=DM−D1x=d·D1x+e·D2x+f·D3x+g (3).
A method of feeding dampening water in a printing machine for controlling a feed rate of dampening water by using two types of detecting patches printed adjacent each other on printed matter and presenting a difference in density variations after printing with varied feed rates of damping water;
- wherein said two types of detecting patches comprise first detecting patches having a halftone area ratio at substantially 100%, and second detecting patches having a halftone area ratio at K×100% K being a coefficient larger than 0 and smaller than 1;
- said method comprising:
- a density measuring step for measuring a density Ds of said first detecting patches and a density Dm from said printed matter;
- a coefficient computing step for computing a coefficient N, by using Yule-Nielsen's equation (4) set out below, from results of measurement obtained in said density measuring step;
- and
- a dampening water feed rate adjusting step for adjusting the feed rate of dampening water based on said coefficient N:
- Dm=−N·Log{1−K(1−10(−Ds/N))} (4).
Dependencies are inferred from the claim text.