EP0488910A1 - Verfahren und Vorrichtung zur Regelung des Feucht- und Farbgleichgewichts auf einer Druckplatte einer Offsetmaschine - Google Patents

Verfahren und Vorrichtung zur Regelung des Feucht- und Farbgleichgewichts auf einer Druckplatte einer Offsetmaschine Download PDF

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Publication number
EP0488910A1
EP0488910A1 EP91420415A EP91420415A EP0488910A1 EP 0488910 A1 EP0488910 A1 EP 0488910A1 EP 91420415 A EP91420415 A EP 91420415A EP 91420415 A EP91420415 A EP 91420415A EP 0488910 A1 EP0488910 A1 EP 0488910A1
Authority
EP
European Patent Office
Prior art keywords
offset plate
water
offset
focal plane
axis
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.)
Granted
Application number
EP91420415A
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English (en)
French (fr)
Other versions
EP0488910B1 (de
Inventor
Laurent Balducci
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.)
ASSOCIATION DE GESTION DE L'ECOLE FRANCAISE DE PAPETERIE ET DE L'IMPRIMERIE
Original Assignee
ASSOCIATION DE GESTION DE L'ECOLE FRANCAISE DE PAPETERIE ET DE L'IMPRIMERIE
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Publication of EP0488910A1 publication Critical patent/EP0488910A1/de
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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
    • B41F33/0063—Devices for measuring the thickness of liquid films on rollers or cylinders
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41F—PRINTING MACHINES OR PRESSES
    • B41F33/00—Indicating, counting, warning, control or safety devices
    • B41F33/0054—Devices for controlling dampening
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S101/00—Printing
    • Y10S101/45—Sensor for ink or dampening fluid thickness or density

Definitions

  • the present invention relates to offset machines and in particular the methods of inking and wetting the offset plate.
  • Figure 1 shows a simplified example of the mechanism of an offset machine.
  • a plate cylinder 1 on which an offset plate 2 is mounted first comes into contact with wetting rollers 3a and 3b and then with ink rollers 4a and 4b.
  • the ink on the plate 2 is then transferred to a cylinder 5 called a blanket.
  • the blanket 5 is in contact with a printing cylinder 6. Paper 7 passing between the cylinders 5 and 6 is printed by the ink present on the blanket 5.
  • the surface of the offset plate 2 is formed in such a way that, during inking, the ink only deposits on desired areas of the plate to constitute an image.
  • FIG. 2 represents a magnification of a section of the offset plate 2.
  • a resin film has been deposited on the rough surface 20 of the plate 2 and then etched according to the image to be reproduced, leaving resin dots 21 of variable dimensions and zones 22 devoid of resin.
  • density the ratio of the surface of the points 21 on the surface of the zones 22.
  • the coverage rate by the ink varies, that is to say that the ink more or less covers the points 21, the water occupying the remaining area.
  • the problem posed is to move as little as possible from the water-ink balance which corresponds to the ideal state where the ink would exactly cover the points 21, in other words, where the coverage rate would be equal to density.
  • the respective amounts of water and ink must be between certain limits, namely an upper limit where the ink would overflow the points 21 during transfer to the blanket 5 and a lower limit where the the water in zones 22 would not entirely cover the ridges of the roughness of the surface 20. If the lower limit is not respected, the ink also adheres to zones 22 and the offset plate must be cleaned.
  • control bars which are printed at the same time as each image. These control bars have several screened areas at different point sizes and at different ideal coverage rates. These control bars are examined visually or with optical densitometers on the printed sheet to determine whether to readjust the wetting and inking settings.
  • the document FR-A-2 556 283 (under priority of the patent applications of the United States of America No. 560 837 of December 13, 1983 and No. 618 252 of June 7, 1984) describes a system for measuring the average quantity of water present on a moving ink roller.
  • the roller is illuminated at a non-normal incidence and the reflected light is collected by several optical sensors.
  • the signals delivered by these sensors are then processed to obtain an indication of the average amount of water on the roller.
  • a disadvantage of this system is that no indication of the coverage rate is obtained on the offset plate, which, as we have seen above, is essential for detecting the water-ink balance.
  • Another drawback is linked to the illumination of the roller at a different incidence from normal, which causes intensity fluctuations at the level of the sensors linked to surface and eccentricity defects of the roller.
  • An object of the present invention is to continuously provide an indication of the water-ink balance.
  • Another object of the invention is to overcome the problems of surface defects and eccentricity.
  • a method for monitoring the water-ink balance in an offset machine which comprises an offset plate fixed to a cylinder, the method comprising the following steps: lighting under normal incidence, with a coherent light source, a predetermined area of the moving offset plate, the density of which is known; collecting in the focal plane of a converging optical system a portion of the light re-emitted around an axis normal to the plane of the illuminated area; and measuring the light intensity in at least one area of the focal plane.
  • the light intensity is measured around said axis.
  • the light intensity is also measured in at least one zone remote from the axis of the lens.
  • the predetermined area is a regularly screened area.
  • the predetermined area is lit in synchronism with the movement of the offset plate.
  • the present invention also provides a device for regulating the water-ink balance in an offset machine comprising an offset plate fixed to a cylinder, and a system for wetting and inking this plate, the device comprising: a coherent light source illuminating under normal incidence a predetermined area of the moving offset plate; a measurement cell comprising a sensor placed in the axis and in the focal plane of a converging optical system, which collects a fraction of the light re-emitted by said area; a servo system taking into account the signal delivered by the sensor to adjust the wetting and / or inking of the offset plate.
  • At least a second sensor is placed in the focal plane of the converging optical system off the axis, and means are provided for acting on the servo system to determine a minimum wetting at from the signal of this second sensor.
  • FIG. 3 represents a device according to the present invention which makes it possible to provide an indication of the water-ink balance.
  • the device has been adapted on a conventional offset machine, for example that of FIG. 1.
  • a coherent light source 30, such as a laser provides a beam which is reflected on a mirror 31 to project, normally on its surface, a light spot on the moving offset plate 2.
  • a converging lens 32 whose axis is normal to the plate 2, supports the mirror 31 and collects the light re-emitted by the illuminated area of the plate.
  • Two sensors 33 and 34 are placed in the focal plane of the lens 32, the sensor 33 being in the axis of the lens.
  • the above system is activated at specific times when the light source 30 illuminates a predetermined area 35 of the plate 2, the characteristics of which are known, in particular the density.
  • This predetermined area is, for example, one of the screened areas of a control bar printed at the same time as each image.
  • This particular arrangement and the use of a coherent light source make it possible to obtain in the focal plane of the lens 32 the Fourier transform of the re-emitted wave from the zone 35. It turns out that the average value of this Fourier transform, which is a light intensity measured by the sensor 33, varies in the opposite direction with respect to the variations in the coverage rate of the area 35. As we know the density of this area, we also know the water balance - ink that it should present.
  • the difference I-I0 is formed between the signal I delivered by the sensor 33 and a reference signal I0 which would correspond to the signal delivered by the sensor in the case where there is water-ink balance in the area 35.
  • the device according to the present invention can be adapted to any offset machine and be associated with a servo system easy to perform by those skilled in the art, which makes it possible to act on the wetting and / or inking settings.
  • the present invention is susceptible to various variations and modifications.
  • to collect the light re-emitted around an axis normal to the illuminated area instead of using a lens, it would be possible to use any other converging light collector optical system and place detectors in the focal plane of this optical system.

Landscapes

  • Inking, Control Or Cleaning Of Printing Machines (AREA)
  • Rotary Presses (AREA)
  • Color Image Communication Systems (AREA)
  • Investigating Or Analysing Materials By Optical Means (AREA)
EP91420415A 1990-11-30 1991-11-22 Verfahren und Vorrichtung zur Regelung des Feucht- und Farbgleichgewichts auf einer Druckplatte einer Offsetmaschine Expired - Lifetime EP0488910B1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR9015385A FR2669855B1 (fr) 1990-11-30 1990-11-30 Procede et dispositif de regulation de l'equilibre eau-encre sur une plaque de machine-offset.
FR9015385 1990-11-30

Publications (2)

Publication Number Publication Date
EP0488910A1 true EP0488910A1 (de) 1992-06-03
EP0488910B1 EP0488910B1 (de) 1995-10-18

Family

ID=9403029

Family Applications (1)

Application Number Title Priority Date Filing Date
EP91420415A Expired - Lifetime EP0488910B1 (de) 1990-11-30 1991-11-22 Verfahren und Vorrichtung zur Regelung des Feucht- und Farbgleichgewichts auf einer Druckplatte einer Offsetmaschine

Country Status (8)

Country Link
US (1) US5249036A (de)
EP (1) EP0488910B1 (de)
JP (1) JPH0691857A (de)
AT (1) ATE129192T1 (de)
CA (1) CA2056171A1 (de)
DE (1) DE69113957T2 (de)
ES (1) ES2082170T3 (de)
FR (1) FR2669855B1 (de)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1201431A1 (de) * 2000-10-23 2002-05-02 Baldwin Jimek AB Vorrichtung und Verfahren zum Detektieren von Farbschankungen in eine Druckmaschine

Families Citing this family (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
AUPQ611200A0 (en) * 2000-03-09 2000-03-30 Commonwealth Scientific And Industrial Research Organisation Determination of change in thickness of dampening solution on offset printing rollers
UA64588A (en) * 2003-07-01 2004-02-16 Pavlo Valentynovych Kandaurov Method for monitoring the layer of fountain solution on printing plate
US6796227B1 (en) 2003-08-18 2004-09-28 Quad Tech Lithographic press dampening control system
DE102008000031B4 (de) * 2008-01-10 2014-07-10 Koenig & Bauer Aktiengesellschaft Verfahren zur Kontrolle einer Anordnung von an Formzylindern einer Druckmaschine angeordneten Druckformen
EP2380741A1 (de) 2010-04-23 2011-10-26 GVT GmbH Verfahren und Vorrichtung zum Messen der Dicke einer Feuchtmittel- oder Farbemulsionsschicht im Offset-Druckverfahren

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2214721B1 (de) * 1972-03-25 1973-06-14 Heidelberger Druckmaschinen Ag, 6900 Heidelberg Verfahren und vorrichtung zum selbsttaetigen ausregeln von schwankungen der farb- und feuchtfluessigkeitsfuehrung an offsetmaschinen
US3981238A (en) * 1972-09-27 1976-09-21 European Rotogravure Association Method and apparatus for determining doctor blade position in a rotogravure process
DE3611645A1 (de) * 1986-04-07 1987-10-08 Grapho Metronic Gmbh & Co Verfahren und vorrichtung zur regelung der farb- und feuchtmittelanteile einer emulsionsschicht auf der druckplatte einer offset-druckmaschine

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
IT1033240B (it) * 1974-03-14 1979-07-10 Grapho Metronic Gmbh & Co Umidificatore in una macchina stampatrice offset con un dispositivo per la regolazione del quantitativo d acqua sulla piastra
DE3479832D1 (en) * 1983-05-17 1989-10-26 Sumitomo Heavy Industries Method of an apparatus for measuring dampening water for printing machine
US4677298A (en) * 1983-12-13 1987-06-30 Kollmorgen Technologies Corporation Method of monitoring ink-water balance on a lithographic printing press
DE3732934A1 (de) * 1987-09-30 1989-04-20 Heidelberger Druckmasch Ag Sensoreinrichtung

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2214721B1 (de) * 1972-03-25 1973-06-14 Heidelberger Druckmaschinen Ag, 6900 Heidelberg Verfahren und vorrichtung zum selbsttaetigen ausregeln von schwankungen der farb- und feuchtfluessigkeitsfuehrung an offsetmaschinen
US3981238A (en) * 1972-09-27 1976-09-21 European Rotogravure Association Method and apparatus for determining doctor blade position in a rotogravure process
DE3611645A1 (de) * 1986-04-07 1987-10-08 Grapho Metronic Gmbh & Co Verfahren und vorrichtung zur regelung der farb- und feuchtmittelanteile einer emulsionsschicht auf der druckplatte einer offset-druckmaschine

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1201431A1 (de) * 2000-10-23 2002-05-02 Baldwin Jimek AB Vorrichtung und Verfahren zum Detektieren von Farbschankungen in eine Druckmaschine

Also Published As

Publication number Publication date
FR2669855A1 (fr) 1992-06-05
ES2082170T3 (es) 1996-03-16
DE69113957T2 (de) 1996-05-15
DE69113957D1 (de) 1995-11-23
US5249036A (en) 1993-09-28
ATE129192T1 (de) 1995-11-15
EP0488910B1 (de) 1995-10-18
CA2056171A1 (en) 1992-05-31
JPH0691857A (ja) 1994-04-05
FR2669855B1 (fr) 1995-07-13

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