EP0601259A1 - Procédé et dispositif pour déterminer la quantité d'encre requise pour une image en impression offset - Google Patents

Procédé et dispositif pour déterminer la quantité d'encre requise pour une image en impression offset Download PDF

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Publication number
EP0601259A1
EP0601259A1 EP92810973A EP92810973A EP0601259A1 EP 0601259 A1 EP0601259 A1 EP 0601259A1 EP 92810973 A EP92810973 A EP 92810973A EP 92810973 A EP92810973 A EP 92810973A EP 0601259 A1 EP0601259 A1 EP 0601259A1
Authority
EP
European Patent Office
Prior art keywords
printing ink
printing
area
film
determined
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP92810973A
Other languages
German (de)
English (en)
Inventor
Franz Sigg
René Rawyler
Kurt Rüegg
Thomas Senn
Hans Ott
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Gretag AG
Original Assignee
Gretag AG
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Gretag AG filed Critical Gretag AG
Priority to EP92810973A priority Critical patent/EP0601259A1/fr
Publication of EP0601259A1 publication Critical patent/EP0601259A1/fr
Withdrawn legal-status Critical Current

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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
    • B41F33/0027—Devices for scanning originals, printing formes or the like for determining or presetting the ink supply

Definitions

  • the invention relates to a method and a corresponding device for determining the amount of printing ink required for a print job in offset printing.
  • Color is toxic and must be disposed of as special waste. Color factories are not interested in taking back old colors, as these can rarely be processed again or mixed again. In addition, paint factories often already have enough of their own waste that they cannot handle in a satisfactory manner. For this reason, not only printers, but also paint manufacturers would be interested in estimating the required amount of ink more precisely beforehand and thus reducing waste.
  • the invention is now intended to remedy this problem and to create a method and a corresponding device with which the ink consumption can be predetermined at a time which is suitable in practice.
  • the print run is usually known. A somewhat larger number is usually expected to take waste into account.
  • plate readers or plate scanners that can determine the area coverage of the printed image on the printing plate.
  • these devices are designed and designed to determine the ink consumption per ink zone on the printing press and thus make it possible to adjust the color profile in advance over the printing width on the printing press. It would certainly be conceivable to use such a conventional plate scanner for a purpose other than that in such a way that the total printed area of a printing form could be determined. However, such a measurement would not be very useful for determining the color consumption, since it takes place too late. In practice, when the printing plates are made, the ink must already be in the printing house.
  • the method according to the invention makes it possible to obtain the required Determine the amount of printing ink much earlier, namely after the production of the original films on the basis of which the printing plates are made.
  • each individual image for a printing form is measured for each printing ink according to its area coverage at the time of the original film production. Suitable devices for this are explained further below.
  • the color layer thickness i.e. The amount of the relevant printing ink per unit area (basis weight) required to achieve a certain color impression on a given substrate (type of paper) is not easy to assess.
  • the ink layer thickness must be adjusted depending on the pigment concentration and pigment efficiency of the printing ink. There are natural limits, too thin or too thick ink layer thicknesses can no longer be processed for printing reasons. Unfortunately, it is not enough to know what percentage of pigments in the color are needed to achieve a certain color strength for a given color layer thickness. Depending on whether the pigments are finely or coarsely ground, and depending on how they are wetted by the varnish, they have a different pigment efficiency (coloring power). Because pigments are one of the most expensive components of an ink, a printing ink manufacturer may pigment less to make the ink cheaper. The result of this is that the printer has to apply a thicker color film (and therefore requires more color) in order to obtain the same optical effect.
  • the color factory can therefore indicate to the printer (within certain tolerances) how many m2 of full area with a kilogram of color can be printed on a given paper for a given color strength. In other words, the basis weight of the printing ink required for the desired color strength can be requested from the ink factory.
  • the size of the total printed area of the halftone film is determined and multiplied by the weight per unit area of the printing ink and the number of sheets to be printed (edition) including subsidy (practically a few percent). The result is the expected ink requirement for the printing ink in question for the print job.
  • the actual ink consumption is slightly higher than the value theoretically resulting from the total printed area, the weight per unit area and the number of copies. This is due to the inevitable loss of color that occurs when setting up the press. The resulting additional consumption depends on the operating conditions of the printing press and must be determined experimentally.
  • the film 1 is transported in the measuring device by a mechanism driven by an electric motor via rollers 2 to 5 line by line in the direction of arrow a, analogous to the paper feed in a printer.
  • the line of the film to be measured is illuminated by an illumination unit 6, which is provided with a window 7 on the film side.
  • the homogeneity of the lighting is only decisive within the measuring spot.
  • a corresponding part of the incident light is absorbed by a partially covered film.
  • the non-absorbed light portion passes through a window 8 into a measuring head 9.
  • the measuring head 9 has light-sensitive electronics 10 inside, consisting of one or more photo receivers, which convert the light portion captured into an electrical signal S.
  • the measuring head can be moved in columns in the direction of arrows b and c by a mechanism driven by an electric motor (Fig. 2). Due to the line-by-line film feed and the column-by-line feed of the measuring head, the entire image is thus divided into a large number of individual image elements.
  • the size of an individual picture element (line width * column width) corresponds to the size of the light-sensitive electronics 10 in the measuring head 9.
  • the measurement signals S corresponding to the individual picture elements are compared by a computing unit 11 with previously measured calibration values.
  • the size of the total printed area can be displayed directly on a display unit 12.
  • the spectral sensitivity of the measuring device should be in the range of approx. 400nm to 500nm. There must be no sensitivity above 550nm, so that red originals (e.g. adhesive strips or ulano foils) can also be measured as black.
  • the device should be possible to measure both positive and negative films and to be able to display the corresponding size of the total printed area on the display 12. Switching between positive and negative films takes place via input option 13.
  • the relative area coverage of the entire film is equal to the average of the relative area coverage of the individual picture elements.
  • the two formulas above for calculating the area coverage only apply to picture elements that are completely covered by the film.
  • films are also required are measured, which are narrower than the width of a complete measuring line. Border elements that are only partially covered by the film and picture elements that lie outside the film material must not be taken into account when calculating the total area coverage.
  • the built-in computing unit 11 is able to recognize those picture elements that lie outside the film material. For their determination, the formula S100 ⁇ (S p * 0.97) (incident light is absorbed to less than 3%) can be used, for example.
  • Film edge elements which must also not be taken into account for the calculation of the total area coverage, are those picture elements that one-sidedly adjoin the picture elements lying outside the film material.
  • the size of the total printed area in m2 is simply calculated by multiplying the relative area coverage of the entire film by the size of the actually measured area in m2.
  • the size of the area actually measured by the measuring device can be determined by the built-in computing unit 11. For this purpose, the number of picture elements used for the measurement is multiplied by the known size of a single picture element.
  • the measuring device for the area coverage of the film is connected to a computer 14 which has inputs 15 for the sizes or parameters N, D, E and S defined above and controls a display 16 on which the calculated amount of color M is output.
  • the display 12 in the measuring device can of course be omitted in this case.
  • the inputs 15 of the computer 14 are arbitrary, e.g. can be realized by adjusting elements or a keyboard.
  • at least some of the parameters can also be stored in the computer, so that they do not have to be re-entered every time.
  • a commercial scanner can of course also be used to determine the area coverage of the raster film. Suitable scanners are flatbed scanners, drum scanners, scanners based on the fax principle with Selfoc lenses, and scanners based on the plotter or printer principle with line-by-line film feed and column-wise moving measuring head.
  • the area coverage can also be captured pixel by pixel with a type of television camera will.
  • the light table does not have to meet any special requirements regarding the homogeneity of the light distribution, since the individual picture elements can be treated separately by calculation.
  • the same applies analogously to pixel-by-pixel measurement by means of a large number of photodiodes, each of which defines a pixel and covers the entire surface of the film or at least a section thereof.
  • the size of the total printed area is determined according to an embodiment of the method according to the invention that is particularly easy to implement in terms of apparatus by measuring the (percentage) area coverage of the raster film and by measuring (if not known, since e.g. standard size) the total area of the film. For the determination of the percentage area coverage, e.g. the device described briefly below.
  • a conventional light table available in every print shop or repro station, is used to illuminate the film.
  • a housing is placed on this light table, which either has no floor on the lower side or has a translucent floor (opal plastic).
  • the housing is black on the inside to prevent light reflections from the film surface from falsifying the measurement result (linearity).
  • the top cover of the case has a small hole in the middle.
  • the actual measuring device lies over this hole.
  • the measuring device has a window at its bottom through which the light to be measured coming from the hole enters.
  • the window is covered with a diffuser (e.g. opal glass or plastic) so that light is assessed uniformly from all directions.
  • the inside of the measuring device has light-sensitive electronics, which linearly show the amount of light incident on a display, either digital or analog.
  • the range of the display scale goes from 0 to 100 percent.
  • the resolution of the ad should be 1%.
  • a tenth of a percent display is too precise and only confuses.
  • the spectral sensitivity to light should be in the range of approx. 400nm to 500nm, there must be no sensitivity above 550nm, so that red originals (e.g. adhesive strips or ulano foils) can also be measured as black.
  • the measurement characteristic of the electronics is a line that is defined by two calibration points.
  • the first point that is easy to find is the one without any light (dark point calibration). Since, according to an advantageous embodiment of the device, it should be possible to measure both positive and negative films, it is desirable for the measuring instrument to display either positive or negative measured values. If there is no light, it means 100% coverage for positive films and 0% for negative films.
  • the maximum size of the measuring field is determined by the size of the housing. Since normally single images or pages are to be measured and not entire printing forms, the measuring field can be relatively small, e.g. 30x40 cm. If a larger film still has to be measured, it must be possible to measure only a section of this film in order to then (seamlessly) add different sections together. In order to make it possible to measure even smaller films, it is desirable to have smaller, exchangeable orifice plates available.
  • the measuring area is smaller than the film to be measured, so that there is no false light at the edge of the film.
  • the measuring area In the case of positive films, the measuring area must also be smaller than the film so that there is no clear film-free zone at the edge of the measuring area.
  • the clear area (cm2) in the bright point calibration corresponds to 100% area. Therefore, the absolute area coverage (size of the entire printed area) is simply calculated by multiplying the percentage area coverage by the clear area.
  • the measurement arrangement described has the advantage that it is very simple and allows fast work.
  • the housing can be improved by a door on the front wall so that the film to be measured can be replaced more easily.
  • brief work instructions can be attached to the housing.
  • the height of the housing must at least correspond to the diagonal of the measuring surface. The higher the housing, the less light is lost at the edges of the measuring surface due to the inclination incident light.
  • the quality of the light table limits the accuracy of the measuring arrangement. Temporal fluctuations in brightness, e.g. caused by fluctuations in the power grid can be greatly reduced by connecting a voltage stabilizer. It should also be noted that changes in the vicinity of the light table can also cause changes in the bright point. Whether the sun is covered by a cloud or not can have an impact on the calibration if the light table is next to a window. An object that is added or removed from the light table on the free glass surface also influences the light intensity in the measuring field. It may therefore be useful to cover the light table around the measuring housing in a suitable manner. If the illuminated area in the measuring field is illuminated unevenly, then various points on the measuring field are weighted unevenly.
  • the area coverage can also be recorded by means of a light table and a CCD camera (charged coupled devices, charge coupled sensors).
  • a large number of picture elements of a film are captured by a CCD camera mounted on a tripod above a light table and transmitted to a data processing system for further processing. Any section of the entire image captured by the camera can be selected for further processing on the associated monitor.
  • the individual picture elements of the desired image section are offset against calibration data obtained by a previous calibration measurement. Efficient calibration can be achieved, for example, by measuring a checkerboard patterned film, which enables the values for 100% and 0% area coverage to be determined simultaneously.
  • any disturbing, temporally changing external light influences must be excluded by means of a suitable cover.
  • inaccuracies are to be expected, which result from point broadening due to different gridings.
  • the user should be able to define the raster in lines / mm or a full tone input for partial image areas previously selected on the monitor.
  • the results from the determination of the area coverage can be evaluated zonally and evaluated for presetting the ink guide elements of the printing press.
  • paper and color-dependent sizes must be included in the calculation of the required ink quantity. This can basically be done in two different ways.
  • the desired color is e.g. selected from a standardized color fan and the amount of ink required to print a specific surface with the selected color and solid density is taken from the information provided by the paint manufacturer.
  • the paper type is already taken into account in the information provided by the paint manufacturer.
  • the ink consumption in kg / print order can be calculated in advance by entering the number of sheets per print job and size per sheet (print sheet).
  • a somewhat different procedure is also possible using a color formulation system, as is usually used in the production of printing inks.
  • the target value (color coordinates) of a color is measured using a spectrophotometer.
  • a formulation system with weighing device, together with the spectrophotometer, enables interactive adjustment of the formulated color to the target value.
  • the basis weight of the calibration stains used for the formulation is known to the formulation system from gravimetric measurements.
  • the recipe can be used to determine the basis weight of the recipe color. By entering the number of printed sheets (number of copies) and the size of the total area per sheet, the ink consumption for the relevant print job can be calculated in advance from the measured area coverage.

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  • Investigating Or Analysing Materials By Optical Means (AREA)
EP92810973A 1992-12-09 1992-12-09 Procédé et dispositif pour déterminer la quantité d'encre requise pour une image en impression offset Withdrawn EP0601259A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
EP92810973A EP0601259A1 (fr) 1992-12-09 1992-12-09 Procédé et dispositif pour déterminer la quantité d'encre requise pour une image en impression offset

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
EP92810973A EP0601259A1 (fr) 1992-12-09 1992-12-09 Procédé et dispositif pour déterminer la quantité d'encre requise pour une image en impression offset

Publications (1)

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EP0601259A1 true EP0601259A1 (fr) 1994-06-15

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EP92810973A Withdrawn EP0601259A1 (fr) 1992-12-09 1992-12-09 Procédé et dispositif pour déterminer la quantité d'encre requise pour une image en impression offset

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Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5812705A (en) * 1995-02-28 1998-09-22 Goss Graphic Systems, Inc. Device for automatically aligning a production copy image with a reference copy image in a printing press control system
US5816151A (en) * 1995-09-29 1998-10-06 Goss Graphic Systems, Inc. Device for alignment of images in a control system for a printing press
US5903712A (en) * 1995-10-05 1999-05-11 Goss Graphic Systems, Inc. Ink separation device for printing press ink feed control
EP1088660A1 (fr) * 1998-04-02 2001-04-04 Think Laboratory Co., Ltd. Procédé pour calculer les quantités consommables de l'encre
DE10152470B4 (de) * 2000-11-23 2014-08-14 Heidelberger Druckmaschinen Ag Verfahren zur Farbvoreinstellung beim Mehrfarbendruck
CN112533393A (zh) * 2020-12-04 2021-03-19 广州兴森快捷电路科技有限公司 Pcb阻焊方法、pcb阻焊系统及存储介质

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2349860A1 (fr) * 1976-04-27 1977-11-25 Maschf Augsburg Nuernberg Ag Appareil explorateur de films
DE3234313A1 (de) * 1981-09-16 1983-03-31 Toshiba Kikai K.K., Tokyo Verfahren und vorrichtung zum messen des prozentualen rasterflaecheninhalts fuer photogravierte filme

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2349860A1 (fr) * 1976-04-27 1977-11-25 Maschf Augsburg Nuernberg Ag Appareil explorateur de films
DE3234313A1 (de) * 1981-09-16 1983-03-31 Toshiba Kikai K.K., Tokyo Verfahren und vorrichtung zum messen des prozentualen rasterflaecheninhalts fuer photogravierte filme

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5812705A (en) * 1995-02-28 1998-09-22 Goss Graphic Systems, Inc. Device for automatically aligning a production copy image with a reference copy image in a printing press control system
US5816151A (en) * 1995-09-29 1998-10-06 Goss Graphic Systems, Inc. Device for alignment of images in a control system for a printing press
US5903712A (en) * 1995-10-05 1999-05-11 Goss Graphic Systems, Inc. Ink separation device for printing press ink feed control
EP1088660A1 (fr) * 1998-04-02 2001-04-04 Think Laboratory Co., Ltd. Procédé pour calculer les quantités consommables de l'encre
DE10152470B4 (de) * 2000-11-23 2014-08-14 Heidelberger Druckmaschinen Ag Verfahren zur Farbvoreinstellung beim Mehrfarbendruck
CN112533393A (zh) * 2020-12-04 2021-03-19 广州兴森快捷电路科技有限公司 Pcb阻焊方法、pcb阻焊系统及存储介质

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