DE102007016981A1 - Method for measuring color quality in web-fed printing - Google Patents

Method for measuring color quality in web-fed printing

Info

Publication number
DE102007016981A1
DE102007016981A1 DE200710016981 DE102007016981A DE102007016981A1 DE 102007016981 A1 DE102007016981 A1 DE 102007016981A1 DE 200710016981 DE200710016981 DE 200710016981 DE 102007016981 A DE102007016981 A DE 102007016981A DE 102007016981 A1 DE102007016981 A1 DE 102007016981A1
Authority
DE
Germany
Prior art keywords
brightness sensor
measurement
web
color
image
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Withdrawn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
DE200710016981
Other languages
German (de)
Inventor
Jean-Claude Mengisen
Matthias Riepenhoff
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.)
Wifag Maschinenfabrik AG
Original Assignee
Maschinenfabrik Wifag
Wifag Maschinenfabrik 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 Maschinenfabrik Wifag, Wifag Maschinenfabrik AG filed Critical Maschinenfabrik Wifag
Priority to DE200710016981 priority Critical patent/DE102007016981A1/en
Publication of DE102007016981A1 publication Critical patent/DE102007016981A1/en
Withdrawn legal-status Critical Current

Links

Classifications

    • BPERFORMING OPERATIONS; TRANSPORTING
    • B41PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41FPRINTING MACHINES OR PRESSES
    • B41F33/00Indicating, counting, warning, control or safety devices
    • B41F33/0036Devices for scanning or checking the printed matter for quality control

Abstract

The present invention relates to a method for measuring inking in web-fed printing, in which the light reflected from a printed web is spectrally and / or color-measured, characterized in that it is measured at different image locations in the printed image.

Description

  • modern Printing machines are increasingly being equipped with control systems to reduce waste and ensure quality. Examples: cutting register, Color register systems, color density control. In sheetfed and in roll commercial printing Control elements printed to assess the print quality. In newspaper printing, it is desirable to control elements to renounce or make it unattractive.
  • WIFAG method for color density control ( DE 101 31 934 A1 ): Instead of control elements, the image information from pre-press can be used. To control the color density, the light reflected from the printed web is measured using a transversely positionable sensor. The measurement signal can z. B. be evaluated with one or more spectrometers. Another possibility is light-sensitive sensors that distinguish certain areas of the optical spectrum using optical filters.
  • at Measurement with a spectrometer equals the spectrum one out many numbers existing array whose individual values the remitted light in a spectral range. Typically, one includes such array some ten to several thousand numbers. Using of color filters or interference filters are obtained for each measurement is an array whose size corresponds to the number of color channels. Independent of the measuring method and the number of spectral ranges you can call an array a spectrum.
  • At the WIFAG procedures are remission spectra on the moving web measured and compared with theoretical values from reference prints. In this case, the measurement of a spectrum takes place transversely at a measuring location to the printing direction over one or more perimeters. A measurement consists of several partial measurements (burst measurement), which are summed.
  • White paper can be measured at the unprinted edge. For broadsheet products in particular, the left and right edges of each page used for paper white measurement. In tabloid productions In particular, the upper and lower edges of the pages can be used.
  • Advantage: The time course of the remitted light repeats periodically. It is sufficient to set the measuring duration to the machine speed vote. A triggering on certain picture elements is not required.
  • difficulty of the procedure: the proportion averaged over a period unprinted area is high (often> 80%). This leads to large noise of Signal. In particular, the method is sensitive to Fluctuations in the paper white and appearances of the printed Back.
  • One new process overcomes this difficulty: the individual Elements of a burst correspond to small image sections. At the same time with The measurement of the spectrum is followed by a measurement of the brightness progression the train. The brightness gradient can be used to image areas corresponding elements of a burst (similar to the procedure) like edit control).
  • Also if the mean of the area coverage is low, finds one usually uses image areas with higher area coverage, the individual elements of a burst can be assigned. This allows a more accurate determination of the solid density.
  • In Usually one also finds elements of a burst, the unprinted ones Picture places correspond, z. B. in the area of the side edges. For broadsheet products, a paper white measurement is not just possible on the right and left edges, but also between the individual pages, ie in the area of the upper and lower Image border. For tabloid products, except the top and bottom Image border also the area of the right and left margins be used. Depending on the template, you can also image within of the type area mirror, which are unprinted, and allow a Papierweissmessung.
  • Example, 1 : A measurement is made using three identical printed copies. Two measuring positions are selected transversely to the web running direction. The beginning of the measurement is arbitrary and is typically within the page. A measurement consists of many partial measurements. The time it takes to measure one page equals n partial measurements.
    • Site 1: Measurements (1,1), (1, n) and (1,2n) belong to the same image locations. The measurements (1, a), (1, n + a) and (1,2n + a) are unprinted areas. The measurements (1, b), (1, n + b) and (1,2n + b) show a high surface coverage.
    • Site 2: Measurements (2,1), (2, n) and (2,2n) belong to the same image locations. The measurements (2, c), (2, n + c) and (2,2n + c) are unprinted areas. The measurements (2, d), (2, n + d) and (2,2n + d) show a high surface coverage.
  • advantageously, the measuring time is chosen as short as possible. Thereby the measuring sites get smaller and you can get higher image positions Find area coverage.
  • By the use of a brightness sensor and the assignment of the partial measurement It is not mandatory for image locations that the measurement time is a multiple of the cycle time of a printing operation. The timing the measuring process is simplified.
  • to Brightness measurement can be a separate sensor (eg contrast sensor) to be used with its own lighting.
  • Advantageous is, however, if the measuring device of the spectral measurement has an additional measuring channel for measuring brightness. The brightness sensor then uses the remitted light from the same Illumination source used for the spectral measurement becomes.
  • The Measurement speed depends on the specific hardware. For spectrometers, the measurement times for continuous Measurement in the range of milliseconds for a partial measurement. Individual photosensors (eg photodiodes) may typically can be evaluated much faster, the measuring times can depending on the bandwidth of the amplifier and analog-to-digital converter in the range of microseconds.
  • Examples of the relationship between spot size, measuring time, web speed and spatial resolution:
    • Measuring field size 5 mm (in web running direction), measuring time 1 ms, web speed 10 m / s. Measuring field size: 15 mm.
    • Measuring field size 0.8 mm (in web running direction), measuring time 2 μs, web speed 10 m / s. Measuring field size: 1 mm.
  • The Brightness measurement is done with smaller spots and shorter ones Measuring times, thus the spatial resolution is higher and the partial bursts can be the corresponding image locations be assigned exactly.
  • The Brightness signal can be used in addition to paper weight measurement be used on small unprinted spots on the page. The Paper white signal of the brightness sensor can be used as a parameter for the determination of the solid density can be used.
  • you can use an optical filter in front of the brightness sensor. This can be z. B. improve the recognition of certain colors. So z. B. the detection of yellow by using a filter improved to increase the color temperature.
  • chromatic colors absorb optical radiation in the visible spectral range. black Ink absorbs in the infrared range. You can use an IR filter In particular, use the optical effect of black ink regardless of the bright colors. In this way is it possible, not just paper white at the unprinted Bodies to measure but also the density of black ink, when applied to underlying paint layers.
  • An example of an optical system, 2 : Lighting beam ( 221 ), Fiber output for lighting ( 225 ), Imaging optics (achromat) for illumination ( 222 ), Deflection mirror for lighting ( 222 ), Paper web ( 200 ), remit light beam for spectral or color measurement ( 211 ), Mirror ( 212 ), Imaging optics for spectral or color measurement ( 213 ), Fiber input for measurement signal, remitted light beam for brightness measurement ( 231 ), Mirror ( 233 ), Imaging optics for brightness sensor ( 232 ), optical filter for brightness sensor ( 234 ), Photodiode ( 235 ).
  • By The use of mirrors allows the beam path in a small space be extended. An extended beam path allows the angles between the illumination beam and the measuring beam to be small become. This achieves a high depth of field. The measuring system becomes less sensitive to fluctuations the distance between optics and paper web.
  • QUOTES INCLUDE IN THE DESCRIPTION
  • This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.
  • Cited patent literature
    • - DE 10131934 A1 [0002]

Claims (12)

  1. Method for measuring color in web-fed printing, in which the light reflected from a printed web is spectrally and / or color-coded, characterized in that it is measured at different image locations in the printed image.
  2. Method according to claim 1, characterized that an additional brightness sensor is used.
  3. Method according to the preceding claim, characterized in that the brightness sensor has a brightness profile determines from which the position of the image is determined, and the spectral measurement is assigned to an image location.
  4. Method according to one of the two preceding claims, characterized in that paper white with the brightness sensor or additionally measured with the brightness sensor.
  5. Method according to one of the three preceding claims, characterized in that a photodiode as a brightness sensor is used.
  6. Method according to one of the four preceding claims, characterized in that the brightness sensor is a filter to better recognize certain colors.
  7. Method according to one of the preceding claims, characterized in that a brightness sensor in the optical System of spectral or color measurement is integrated.
  8. Method according to one of the preceding claims, characterized in that a brightness sensor is provided, the light from the same exposure source as a spectral or Color sensor receives.
  9. Method according to one of the preceding claims, characterized in that paper white additionally with the brightness sensor is measured.
  10. Method according to one of the preceding claims, characterized in that paper white at the edges and / or in unprinted image areas.
  11. Method according to one of the preceding claims, characterized by the use of light guides.
  12. Method according to one of the preceding claims, characterized in that by means of an IR filter black of separated from the chromatic colors.
DE200710016981 2007-04-10 2007-04-10 Method for measuring color quality in web-fed printing Withdrawn DE102007016981A1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
DE200710016981 DE102007016981A1 (en) 2007-04-10 2007-04-10 Method for measuring color quality in web-fed printing

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
DE200710016981 DE102007016981A1 (en) 2007-04-10 2007-04-10 Method for measuring color quality in web-fed printing
PCT/EP2008/002843 WO2008122443A1 (en) 2007-04-10 2008-04-10 Method for measuring the colour quality in web-fed printing
EP20080735152 EP2134546A1 (en) 2007-04-10 2008-04-10 Method for measuring the colour quality in web-fed printing

Publications (1)

Publication Number Publication Date
DE102007016981A1 true DE102007016981A1 (en) 2008-10-16

Family

ID=39712557

Family Applications (1)

Application Number Title Priority Date Filing Date
DE200710016981 Withdrawn DE102007016981A1 (en) 2007-04-10 2007-04-10 Method for measuring color quality in web-fed printing

Country Status (3)

Country Link
EP (1) EP2134546A1 (en)
DE (1) DE102007016981A1 (en)
WO (1) WO2008122443A1 (en)

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE10131934A1 (en) 2001-07-02 2003-01-30 Wifag Maschf Measurement and control of color in web-fed printing

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB8908271D0 (en) * 1989-04-12 1989-05-24 Tecscan Electronics Ltd Monitoring apparatus for colour printing press
DE4237004C2 (en) * 1992-11-02 1996-07-04 Mohndruck Reinhard Mohn Ohg Process for online measurement of the coloring of printed products
DE19516333A1 (en) * 1995-05-04 1996-11-07 Heidelberger Druckmasch Ag Process for controlling or regulating the coloring of a printing press
DE10013876B4 (en) * 1999-04-08 2013-10-02 Heidelberger Druckmaschinen Ag Method for controlling the coloring when printing with a printing machine
FI115205B (en) * 2002-09-04 2005-03-31 Data Instmsto Oy Printing quality method and apparatus for on-line monitoring
DE102005041179A1 (en) * 2005-08-31 2007-03-01 Man Roland Druckmaschinen Ag Typographic process e.g. color registering, regulating method for printing machine, involves determining pre-press based target value from pre-press data and under consideration of data about characteristic of sensor

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE10131934A1 (en) 2001-07-02 2003-01-30 Wifag Maschf Measurement and control of color in web-fed printing

Also Published As

Publication number Publication date
WO2008122443A1 (en) 2008-10-16
EP2134546A1 (en) 2009-12-23

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Legal Events

Date Code Title Description
8128 New person/name/address of the agent

Representative=s name: SCHWABE, SANDMAIR, MARX, 81677 MUENCHEN

8127 New person/name/address of the applicant

Owner name: WIFAG MASCHINENFABRIK AG, BERN, CH

R119 Application deemed withdrawn, or ip right lapsed, due to non-payment of renewal fee

Effective date: 20111101