WO1987006190A1 - Procede pour regler la qualite de tirage - Google Patents

Procede pour regler la qualite de tirage Download PDF

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Publication number
WO1987006190A1
WO1987006190A1 PCT/FI1987/000049 FI8700049W WO8706190A1 WO 1987006190 A1 WO1987006190 A1 WO 1987006190A1 FI 8700049 W FI8700049 W FI 8700049W WO 8706190 A1 WO8706190 A1 WO 8706190A1
Authority
WO
WIPO (PCT)
Prior art keywords
web
light
test
sensor
spot
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.)
Ceased
Application number
PCT/FI1987/000049
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English (en)
Inventor
Kimmo Simomaa
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.)
VTT Technical Research Centre of Finland
Original Assignee
VTT Technical Research Centre of Finland
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 VTT Technical Research Centre of Finland filed Critical VTT Technical Research Centre of Finland
Publication of WO1987006190A1 publication Critical patent/WO1987006190A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

Links

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
    • B41F33/0081—Devices for scanning register marks

Definitions

  • the present invention relates to a method for controlling print quality in a web printing press by measuring at least the darkness of the colour surface of the printed product by aid of a web sensor, wherein on the moving paper web there is arranged a test spot and/or test patterns in the middle and/or aside the saleable printing, and the operation of the web sensor is synchronized with the said test spots while they move, along with the paper web, past the sensor, so that from the light source of the said web sensor there is focused a light beam onto the paper web, and the scatterings of the said light beam from the test surface are measured by employing a light detecto .
  • test spots indicating the relative shifting of the partial images printed using separate inks i.e. cyan, magenta, yellow and black
  • the web sensor is synchronized with the said test spots while they move past the sensor along with the paper web.
  • a typical feature of the prior art web densitometers has been that they measure the optical reflection density of the test spot within an area of roughly 9 square millimeters, which means that the light beam focused thereon has a diameter of roughly 3-4 mm. This practice originates from the manual desktop densitometers, where the measuring can be arranged to take place exactly at the desired spot in the printing.
  • the determination of the measuring spot is more problematic: the 3-4 mm light spot must fall on the printed test surface, such as the test spot, the length whereof - in the moving direction of the paper web - is in practice 6 mm at the most.
  • the measuring operation In order to make a 3-4 mm spotlight to fall exactly on the test area, the measuring operation must be synchronized at the minimum accuracy of +/-1,5 mm. In reality the synchronization accuracy must be roughly +/- 0.5 mm,- if absolute certainty is required that the light detector of the web sensor does not see anything outside the 6 mm test area. Observation of the vicinity is a drawback, if the test area represents black printing and the vicinity is a light printing sheet or the like. Except that the 3-4 mm test area is a general practice, it is also indirectly recommended by the DIN standard 16536/16527: the large size of the test spot helps to filter the variation caused by irregularities in the paper and the printing.
  • the diameter, or the largest dimension of the light spot formed on the paper web by the light beam in the motional direction of the web could be for instance 1-2 mm, in which case the synchronizing of the measurement with the 6 mm test area becomes easier, or, with careful synchronizing, a test pattern of even 4 mm can be used, which helps in selling the web sensors for customers in the printing trade.
  • the diminishing of the test area is easily compensated by repeating the measurement on successive sheets or equivalent, and by calculating the measuring result proper as an average of the obtained partial measurements.
  • the edge readings are rejected. If the measuring area is reduced for instance to 1/10 of the original, the measurement is carried out on 10 successive sheets, or on 3 sheets, if for instance 3-4 measurements are performed on each sheet.
  • the good control interval i.e. 20 sheets, can be maintained in the automated density control .
  • a small-size light spot can be realized by aid of a conventional lens arrangement, and the employed light source can be either a semiconductor lamp, a filament lamp or a Xenon flash tube, which are all known in the prior art.
  • a new method for the projection of light onto paper is the use of cylindrical lenses.
  • a cylinder lens which is installed in the transversal direction of the paper web, there can easily be realized the above mentioned short, small-sized light spot, which in this case means the duration of the illumination in the driving direction.
  • the cylinder lens has the advantage that by employing one single light source, there can also be illuminated for instance the adjacent test area or test spot, which reduces the amount of required light sources. In the transversal direction of the web the light spot is limited for instance by using mechanical apertures.
  • the reduction of the light spot size used in the web densitometer measurement according to the invention makes it possible also to measure the registration of the colours with the same sensor.
  • the data measured by the web sensor are processed for example simultaneously in two separate data processing units: there is provided specific equipment for measuring the density and register respectively.
  • the measuring of the register is carried out according to generally known principles.
  • the employed test pattern in the register measurement can naturally be of any possible type.
  • the darkness of the colour surface could in fact be measured on the basis of the register test pattern, if the sensor of the present invention were utilized.
  • the usefulness of the measuring arrangement here described works both ways: the accurate definition of the darkness on the basis of the density computation would make the definition of the edge position, i.e. the registration, more reliable.
  • the greatest advantage gained by the twofold darkness and registration sensor is, however, the fact that the manufacturing costs are essentially reduced, and moreover the instalment of one common measuring sensor clamping bar in the printing press will be simple.
  • figure 1 is an illustration of a web sensor applying the method of the present invention
  • figure 2 is an illustration of the same web sensor seen from above
  • figure 3 illustrates the comparison between a web sensor (A) employing a large light spot and measuring the darkness of the colour surface, and the web sensor (B) operated according to the method of the present invention
  • figure 4 is an illustration of a measuring system according to the method of the present invention.
  • the web sensor of figure 1 comprises the light source 1, the optics connected thereto, which include for instance the condenser lens 2 and the focusing lens 3.
  • the operation of the web sensor is synchronized with the said test spots while they move past the sensor along with the paper web.
  • the motional direction of the paper web 4 is upwards from the level of figure 1.
  • the light detector or detectors 6 are arranged at an angle with respect to the light beam directed towards the paper web, most advantageously so that the diffusely reflected, i.e. scattered light from the test pattern 5 can thereby be observed.
  • the light beam of the light source 1 is directed against the web surface at an angle of 45 , and the detector is arranged at an angle of 90 with respect to the web surface.
  • the focusing lens 3 is like in figures 1 and 2.
  • the cylinder lens 3 is placed transversally with respect to the moving direction of the web, and the width of the light spot 7 is preferably 1-2 mm.
  • the light spots are limited for instance by aid of the mechanical aperture 3a.
  • 5 adjacent test spots can be illuminated (detectors 61, 62, 63, 64 and 65).
  • the use of the small-size light spot enables the combination of two completely different measurements, i.e. the measurement of the darkness of the colour surface and the registration of different colours.
  • Test areas are needed in both measurements, but they are different in nature, wherefore in conventional measurements both have their own respective marks, which consequently take up a lot of the printing space on the web.
  • the registration measuring marks are relatively small, and usually there is only needed a right-angled triangle in order to measure the transversal and longitudinal registration of different colours. Thus the number of marks in four-colour printing is four.
  • the location of the edges is the only feature of the marks to be measured. Normally these are observed by aid of a light source strongly focused by optics and by aid of a detector.
  • the said measuring arrangement comprises the web sensor 11, the tachometer 12, the synchronizing circuit 13, the fast A/D converter 14, the data processing unit 15 such as a microprocessor, the memory 16 and the interface units 17, 18 for instance for the user and additional data processing and/or process control activities respectively.
  • Both measurements are carried out by aid of the same web sensor 11, or by aid of two separate web sensors, which are connected for instance to the same fastening clamp or the like. While measuring the darkness of the colour surface, the measurement is repeated on successive printing sheets or equivalent, and the measuring result proper is calculated as an average of the partial measurements.
  • the optical intensity of the scattered radiation which is used in the measurement of the darkness of the colour surface, is utilized while defining the accurate location of the edges of the test surfaces, on the basis whereof the reciprocal registrations of the different colours are calculated, whereafter they are available for the information of the user and/or feedable into the adjusting system of the printing process.

Landscapes

  • Inking, Control Or Cleaning Of Printing Machines (AREA)

Abstract

Procédé pour régler la qualité d'impression dans une presse rotative en mesurant au moins le degré de noir de la surface couleur du produit imprimé à l'aide d'un capteur de bande. Sur la bande de papier en déplacement, on dispose un point d'essai (9) et/ou des motifs d'essai au milieu du tirage à vendre et/ou à côté de celui-ci. Le fonctionnement du capteur de bande est synchronisé avec ledit point d'essai lors de leur défilement le long de la bande de papier devant le capteur. Un faisceau lumineux provenant de la source lumineuse du capteur de la bande est focalisé sur celle-ci, et les reflets dudit faisceau lumineux provenant du point d'essai sont mesurés à l'aide d'un détecteur de lumière. L'invention est caractérisée en ce que le point lumineux (10) formé sur la bande de papier par le faisceau lumineux est limité en comparaison avec un point lumineux normalement utilisé (8) au moins dans le sens de déplacement de la bande de papier pour que sa dimension reste constante entre environ 1 et 2 mm. Le point lumineux limité du même capteur de bande mesure le repérage réciproque des différentes couleurs. De plus, les mêmes points d'essais et/ou motifs sont utilisés pour la mesure du degré de noir des surfaces couleurs et du repérage des différentes couleurs.
PCT/FI1987/000049 1986-04-14 1987-04-14 Procede pour regler la qualite de tirage Ceased WO1987006190A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FI861578A FI861578A0 (fi) 1986-04-14 1986-04-14 Foerfarande foer kvalitetskontroll av tryckning.
FI861578 1986-04-14

Publications (1)

Publication Number Publication Date
WO1987006190A1 true WO1987006190A1 (fr) 1987-10-22

Family

ID=8522455

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/FI1987/000049 Ceased WO1987006190A1 (fr) 1986-04-14 1987-04-14 Procede pour regler la qualite de tirage

Country Status (2)

Country Link
FI (1) FI861578A0 (fr)
WO (1) WO1987006190A1 (fr)

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH09218097A (ja) * 1995-11-01 1997-08-19 Xerox Corp 多機能センサ、フルカラー電子写真印刷マシン、並びに色彩値、光沢値及び見当合わせマーク値の決定方法
EP1219420A1 (fr) * 2000-12-27 2002-07-03 Bobst S.A. Dispositif de lecture de marques de repérage dans une machine d'impression polychrome
WO2004022342A1 (fr) * 2002-09-04 2004-03-18 Insinööritoimisto Data OY Procede et appareil pour le controle en ligne de la qualite d'impression
EP1156387A3 (fr) * 2000-05-17 2005-03-23 Eastman Kodak Company Méthode et dispositif d'ajustement de registration
EP1156384A3 (fr) * 2000-05-17 2005-03-23 Eastman Kodak Company Méthode et dispositif d'ajustement de la régistration dans une imprimante couleur et imprimante couleur
GB2408799A (en) * 2003-01-14 2005-06-08 Qti Presstech Ltd Improvements to scanning heads
EP2191973A1 (fr) 2008-12-01 2010-06-02 Seiko Epson Corporation Appareil d'enregistrement

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2060000A1 (de) * 1970-12-05 1972-06-15 Hell Rudolf Dr Ing Gmbh Verfahren und Anordnung zur Regelung der Farbgebung beim Drucken
SE382944B (sv) * 1971-11-03 1976-02-23 Gretag Ag Sett och anordning for maskinell metning av fergtethet hos pa en lopande bana anbringade tryckferger, spec. vid flerfergsdjuptryck
GB2064113A (en) * 1979-11-28 1981-06-10 Licentia Gmbh Monitoring Colour of Printed Web
GB2066949A (en) * 1980-01-09 1981-07-15 Dainippon Printing Co Ltd Print inspecting device
EP0136542A2 (fr) * 1983-09-20 1985-04-10 Kollmorgen Corporation Procédé pour commander l'impression en couleurs, utilisant des surfaces de contrôle en demi tons

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2060000A1 (de) * 1970-12-05 1972-06-15 Hell Rudolf Dr Ing Gmbh Verfahren und Anordnung zur Regelung der Farbgebung beim Drucken
SE382944B (sv) * 1971-11-03 1976-02-23 Gretag Ag Sett och anordning for maskinell metning av fergtethet hos pa en lopande bana anbringade tryckferger, spec. vid flerfergsdjuptryck
GB2064113A (en) * 1979-11-28 1981-06-10 Licentia Gmbh Monitoring Colour of Printed Web
GB2066949A (en) * 1980-01-09 1981-07-15 Dainippon Printing Co Ltd Print inspecting device
EP0136542A2 (fr) * 1983-09-20 1985-04-10 Kollmorgen Corporation Procédé pour commander l'impression en couleurs, utilisant des surfaces de contrôle en demi tons

Cited By (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0772345A3 (fr) * 1995-11-01 1998-05-20 Xerox Corporation Dispositif de colorimétrie, lustre et contre-réaction d'alignement dans un appareil d'impression en couleurs
JPH09218097A (ja) * 1995-11-01 1997-08-19 Xerox Corp 多機能センサ、フルカラー電子写真印刷マシン、並びに色彩値、光沢値及び見当合わせマーク値の決定方法
EP1156387A3 (fr) * 2000-05-17 2005-03-23 Eastman Kodak Company Méthode et dispositif d'ajustement de registration
EP1156384A3 (fr) * 2000-05-17 2005-03-23 Eastman Kodak Company Méthode et dispositif d'ajustement de la régistration dans une imprimante couleur et imprimante couleur
US7170648B2 (en) 2000-12-27 2007-01-30 Bobst, S.A. Device for scanning register marks into a polychrome printing machine
EP1219420A1 (fr) * 2000-12-27 2002-07-03 Bobst S.A. Dispositif de lecture de marques de repérage dans une machine d'impression polychrome
WO2004022342A1 (fr) * 2002-09-04 2004-03-18 Insinööritoimisto Data OY Procede et appareil pour le controle en ligne de la qualite d'impression
GB2408799B (en) * 2003-01-14 2005-12-21 Qti Presstech Ltd Improvements to scanning heads
US7119820B2 (en) 2003-01-14 2006-10-10 Quad/Tech, Inc. Scanning heads
GB2408799A (en) * 2003-01-14 2005-06-08 Qti Presstech Ltd Improvements to scanning heads
EP2191973A1 (fr) 2008-12-01 2010-06-02 Seiko Epson Corporation Appareil d'enregistrement
EP2191973B1 (fr) * 2008-12-01 2014-10-29 Seiko Epson Corporation Appareil d'enregistrement
US8939666B2 (en) 2008-12-01 2015-01-27 Seiko Epson Corporation Recording apparatus for detecting marks on targets

Also Published As

Publication number Publication date
FI861578A0 (fi) 1986-04-14

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