Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
  • B41F—PRINTING MACHINES OR PRESSES
  • B41F33/00—Indicating, counting, warning, control or safety devices
  • B41F33/0036—Devices for scanning or checking the printed matter for quality control
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
  • B41P—INDEXING SCHEME RELATING TO PRINTING, LINING MACHINES, TYPEWRITERS, AND TO STAMPS
  • B41P2233/00—Arrangements for the operation of printing presses
  • B41P2233/10—Starting-up the machine

Definitions

• the invention relates to a method for correcting local, machine-related Coloring errors on rotary printing presses, which as banding, ink drop or as Stenciling in the finished printed product, the quality of which can decrease.
• the offset printing process due to the design of the offset printing units, it is not possible to color a printed sheet completely uniformly or, for a given subject, the halftone dots with a constant layer thickness.
• the inking of the printing form spanned on the circumference of a plate cylinder takes place continuously with an ink film using an offset printing unit, which is previously reduced to a specific ink film thickness by a plurality of friction or bridge rollers.
• the ink removal takes place discontinuously, however, because on the one hand the ink removal depends on the subject and on the other hand the peripheral surfaces of the plate cylinder receiving the printing form are discontinuous through the clamping channels.
• Interferences in the ink transfer for example at the interface from the inking unit to the surface of the plate cylinder delivering the ink to the transfer cylinder, at the interface between the printing form cylinder and transfer cylinder surfaces and at the interface between the surface of the transfer cylinder, which is usually given by a rubber-like elevator, with the Printing substrate leads to non-uniformities, which can affect the transferred ink layer thicknesses as well as the dot size generated in relation to the screen areas.
• the resulting effects are streaking, ink drop in the printing direction and stenciling effects.
• the relationships between these phenomena in the inking system are quite complex and cannot be viewed in isolation from one another.
• the invention has for its object machine-related Correct staining errors locally.
• the inking behavior of the printing form is machine-specific already in the prepress stage possible, so that the non-uniformity effects appearing later in the Coloring of the surface of the printing form is maintained during printing form production and can even out when printing later.
• proposed processes can not only be machine-specific properties global form but locally depending on the location of their occurrence as a function of Maintain halftone values and thus the quality of the print product to be produced significantly increase.
• the Coloring behavior of the printing units determined using test forms for the maximum format.
• the determination for the maximum format offers the advantage of using this as a reference value or Reference print product to go out and from this the determined To be able to convert coloring irregularities to smaller formats.
• the method can be used Coloring non-uniformity of the rotary printing press on only one printing unit can be determined as representative. This offers the advantage that only one of several Printing units must be selected so that the calibration within the Prepress a time advantage by only evaluating a printing unit leaves. In the case of a multicolor printing machine which, for example, has 4, 6 or 8 printing units Including series connected in series, this represents a significant time advantage.
• subject-dependent coloring irregularities the modification of the color separations of a Printing form, be it in plate form or as a printing sleeve or a film based on the data of the raster image processor depending on the subject.
• Cosmetic irregularities occur especially when areas with high Screen tones and areas with extremely low screen tones in print are narrow lie together.
• the method proposed according to the invention cannot only the behavior of the generation of Coloring irregularities but also that caused by the subject to be printed Coloring irregularities occurring due to extremely different Screen tone values are taken into account.
• the determined Coloring characteristics of the printing units or the individual printing units of one Transfer multicolour rotary press in the form of a profile to prepress become.
• the profiles can be transferred in tabular form, what their Further processing in the increasingly digital prepress is easier designed.
• the solution proposed according to the invention can be used to modify the halftone values when specifying the Screen tone fluctuations within the prepress stage during printing form production hold. This means that a printing form to be used later in the corresponding printing unit is be it in plate or sleeve form, prepared so that the resulting Coloring irregularities are maintained.
• digital Equipment of the corresponding prepress within the prepress Modification of the halftone tone values during the imaging process in digital Printing form imaging process e.g. in computer-to-press (direct imaging) Use imaging in the printing press as well as in the digital one Exposure of films or printing plates.
• the inking behavior of a multi-color rotary printing machine is after evaluation of Test printing based on previous print jobs known with sufficient accuracy. From Test printing or data already available from the previous print jobs Coloring non-uniformities with regard to color drop in the printing direction, which is more evident Stencil effects depending on the color assignment and the banding coupled by means of the method proposed according to the invention with the data which are at the printing form production of the respective print job to be carried out.
• the color nonuniformities occur depending on the subject, like this especially if the stencil effect is the case, the die Corrections relating to coloring nonuniformities are made depending on the subject.
• the subject creation data i.e. the Illustrations of the printing form in the prepress stage are known from this the color nonuniformity of the printing units Multicolor rotary press the corresponding corrections of the Coloring non-uniformities are determined and in the production of the corresponding Printing form per printing unit are taken into account.
• other effects such as the color drop of the printed product to be produced Be independent of the subject.
• the transfer of the coloring characteristics of the individual printing units Multi-color rotary printing press, or the necessary corrections can be in the form a profile, for example a multidimensional look-up table Prepress to be transferred. It is conceivable to couple the profile to the one Coloring behavior describing ICC profile of the printing press, to which the have the prepress data to be transferred attached in the form of an attachment. Can a transmission of the correction data to compensate for the resulting Coloring non-uniformities take place standardized per printing unit, is one Further processing of this data within prepress at Printing form production also to be carried out as standard and produces essential there less effort.
• the resolution of the data to be transferred in table form Coloring irregularities can be adapted to the error gradients that occur his.
• the color drop, stenciling, streak effects can also be caused by occurring amplitude, gradient, and the location of their occurrence characterized in more detail become.
• the correction of the screen tone values in screen printing processes can be done at the prepress stage two places of printing plate production are carried out.
• raster image processor processing the image data or during the imaging process in a digital Plate or film imagesetters or the computer-to-press process can both flat printing forms and sleeve-shaped printing forms are exposed.
• Methods proposed according to the invention can ensure that the location of the Correction on the surface of the images to be imaged or exposed Printing form matches the location of the occurrence of the error in the print. Only like that occurring color non-uniformities can be compensated locally, or at Keep the production of the appropriate color separation of a printing form, so that the effects of color drop or stencil effects Compensate for stenciling tendencies.
• the machine states i.e. Printing unit states when recording the fault pattern and are largely identical when printed later, if they influence the location of the error to have. If there is no influence on the location of the error that occurs, the Taking into account the prevailing machine conditions when recording the Error picture and irrelevant when printing later.

Landscapes

• Engineering & Computer Science (AREA)
• Quality & Reliability (AREA)
• Printing Methods (AREA)
• Inking, Control Or Cleaning Of Printing Machines (AREA)
• Manufacture Or Reproduction Of Printing Formes (AREA)
• Facsimile Image Signal Circuits (AREA)
• Accessory Devices And Overall Control Thereof (AREA)

Applications Claiming Priority (2)

Publications (3)

Family

ID=7654357

Family Applications (1)

Country Status (6)

Cited By (6)

Families Citing this family (9)

Citations (4)

Family Cites Families (8)

• 2000
  • 2000-08-31 DE DE10042680A patent/DE10042680A1/de not_active Withdrawn
• 2001
  • 2001-07-20 CA CA002353289A patent/CA2353289C/fr not_active Expired - Fee Related
  • 2001-07-30 AT AT01117735T patent/ATE388018T1/de not_active IP Right Cessation
  • 2001-07-30 EP EP01117735A patent/EP1184176B1/fr not_active Expired - Lifetime
  • 2001-07-30 DE DE50113682T patent/DE50113682D1/de not_active Expired - Lifetime
  • 2001-08-24 JP JP2001254154A patent/JP5280598B2/ja not_active Expired - Fee Related
  • 2001-08-31 US US09/944,578 patent/US6694883B2/en not_active Expired - Fee Related

Patent Citations (4)

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