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WO1992004661A1 - Procede de reglage d'unites d'analyse graphique et unite d'analyse munie d'un dispositif de reglage - Google Patents

Procede de reglage d'unites d'analyse graphique et unite d'analyse munie d'un dispositif de reglage Download PDF

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Publication number
WO1992004661A1
WO1992004661A1 PCT/DK1991/000252 DK9100252W WO9204661A1 WO 1992004661 A1 WO1992004661 A1 WO 1992004661A1 DK 9100252 W DK9100252 W DK 9100252W WO 9204661 A1 WO9204661 A1 WO 9204661A1
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WIPO (PCT)
Prior art keywords
exposure surface
light source
adjusting
scanner
spinner
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/DK1991/000252
Other languages
English (en)
Inventor
Allan Vincent Andersen
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Individual
Original Assignee
Individual
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Filing date
Publication date
Application filed by Individual filed Critical Individual
Publication of WO1992004661A1 publication Critical patent/WO1992004661A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N1/00—Scanning, transmission or reproduction of documents or the like, e.g. facsimile transmission; Details thereof
    • H04N1/04—Scanning arrangements, i.e. arrangements for the displacement of active reading or reproducing elements relative to the original or reproducing medium, or vice versa
    • H04N1/06—Scanning arrangements, i.e. arrangements for the displacement of active reading or reproducing elements relative to the original or reproducing medium, or vice versa using cylindrical picture-bearing surfaces, i.e. scanning a main-scanning line substantially perpendicular to the axis and lying in a curved cylindrical surface
    • H04N1/0607—Scanning a concave surface, e.g. with internal drum type scanners
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    • H04N1/024—Details of scanning heads ; Means for illuminating the original
    • H04N1/032—Details of scanning heads ; Means for illuminating the original for picture information reproduction
    • H04N1/036—Details of scanning heads ; Means for illuminating the original for picture information reproduction for optical reproduction
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    • H04N1/047—Detection, control or error compensation of scanning velocity or position
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    • H04N1/0607—Scanning a concave surface, e.g. with internal drum type scanners
    • H04N1/0621—Scanning a concave surface, e.g. with internal drum type scanners using a picture-bearing surface stationary in the main-scanning direction
    • H04N1/0635—Scanning a concave surface, e.g. with internal drum type scanners using a picture-bearing surface stationary in the main-scanning direction using oscillating or rotating mirrors
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    • H04N1/0671—Scanning arrangements, i.e. arrangements for the displacement of active reading or reproducing elements relative to the original or reproducing medium, or vice versa using cylindrical picture-bearing surfaces, i.e. scanning a main-scanning line substantially perpendicular to the axis and lying in a curved cylindrical surface with sub-scanning by translational movement of the main-scanning components
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Definitions

  • a method of adjusting graphical scanner units and a scanner unit having adjustment means is a method of adjusting graphical scanner units and a scanner unit having adjustment means.
  • the present invention relates to a graphical scan ⁇ ner unit e.g. of the type which comprises a drum shaped holder for a graphical film or printing plate mounted on the inside of the drum and a fast rotating spinner mounted centrally in the drum and carrying an inclined mirror or prism for radially reflecting an axially ap ⁇ plied laser beam from a beam modulator, the spinner being axially displaceable relative to the drum such that by a combined rotation and displacement it can cause the light beam on the working surface at the in ⁇ side of the drum to describe a screw shaped working line with closely juxtaposed windings.
  • a graphical scan ⁇ ner unit e.g. of the type which comprises a drum shaped holder for a graphical film or printing plate mounted on the inside of the drum and a fast rotating spinner mounted centrally in the drum and carrying an inclined mirror or prism for radially reflecting an axially ap ⁇ plied laser beam from a beam modulator, the spinner being axially displaceable relative
  • This technique which is also known with the use of a light beam inwardly against a fast rotating cylinder, is widely applied for production of graphical film or printing plates based on computer read printing patterns, the computer being used for controlling the beam modulator, which will then serve to enable and disable the passage of the light beam, for producing the • 'pixels*' or image elements, of which the finally exposed image consists, the pixels typically having a size of 10 x 10 micrometers.
  • the spinner rotates with a speed of 200-400 r.p.s or, re ⁇ spectively, when the drum rotates at normally 100-200 r.p.s., a working surface can be exposed reasonably rapidly, and compared with other scanning techniques this technique is relatively simple.
  • the light beam should hit the spinner highly accurately in the axis of rotation there- of, and this axis should be placed equally accurately coinciding with the axis of the drum, just as the drum should be of an accurately circular cylindrical shape.
  • the latter condition implies that the drum will be ex ⁇ tremely expensive if produced with optimal accuracy; typically the drum diameter may be some 300 mm, and already a deviation of ten micrometers of this diameter will be undesirable, whether appearing in the longi ⁇ tudinal or the peripheral direction. So far it has been necessary to work with a suitable compromise between accuracy and price of the drum, although with an as ⁇ sociated recognition of the facts that the result cannot then be as perfect as desirable.
  • both the spinner and the beam gene ⁇ rator are mounted on very finely adjustable supports, such that these parts can be adjusted into exactly cen ⁇ tral and co-axial positions relative to the drum, and the associated adjustments can be effected manually at the beginning of each working operation with the use of various auxiliaries. It is then to be accepted, however, that the perfect initial adjustment will not remain perfect * if or when the operational conditions change during the operation itself due to wrynesses of the drum-shape; it will be very difficult to effect inter ⁇ mediate operational stops for carrying out control measurements and readjustments.
  • the problem will exist that it is necessary to chose an adjustment compromise, should the drum at the relevant place be slightly elliptical; the spinner rotates with a highly constant angular velocity, and when the produced pixels are of a constant duration the associated length of the working or exposing line will be dependent of the radius of the working surface, whereby for a weakly varying radius there will easily be produced visible distortions of the exposed printing image.
  • the present invention is based on the recognition that it is possible to complete the discussed type of units in a manner such that it will be relatively easy to achieve a dynamical adjustment of the working ac ⁇ curacy in both the length and the peripheral directions of the drum, i.e. in such cases in which the drum is not extremely accurately shaped. In turn, this will imply that generally it will be possible to make use of rela ⁇ tively very cheap drums, yet still with an obtainable, fully acceptable working result.
  • the spinner can be pro ⁇ vided with an outer, co-axially rotating sensor having at its outer end sensing means for detecting the distance outwardly to the inner drum or working surface and being operatively connected with a control unit affecting both automatically operating positioning means for centering of the spinner unit and means for control ⁇ ling the duration of the single pixel impulses, all in a manner such that currently there will be effected both an adjustment of the centered position of the spinner unit and an adjustment of the duration of the single pixels in response to the detected irregularities in the desired circular cylindrical shape of the working sur ⁇ face.
  • the said co-axially rotating sensor unit may have distance sensing means mounted with noticeable axial spacing, whereby it is possible to concurrently detect the axial direction of the following cylinder section to be used, as well as an adjustment of the spinner to this direction.
  • the spinner may also be provided with means for parallel reflection of a light beam to a co-rotating sensor that will receive and de ⁇ tect the radiation for supervising its direction per ⁇ pendicularly against the working surface and, respec ⁇ tively, for effecting an adjustment of the beam genera- tor for a follow-adjustment of the beam direction and centering in response to detected changes of the orien ⁇ tation of the spinner.
  • the rotating sensor part is rotated relatively slowly, e.g. with only a single or two revolutions per second, as this will be sufficient for the detection of the changes in shape or direction that may occur in the drum surface in the area thereof next to be scanned.
  • current adjustments can be made such that the centering will be correct, as well as a dynamic control of the pixel duration such that the pixel length will be correct during the single revolutions of the spinner even in areas, where the cylinder cross-section as a whole is not exact circular.
  • drum bodies of course, should still be carefully produced, but it is an essential effect of the invention that they will not have to be produced with extreme accuracy for the achievement of good and fully usable results.
  • the partial areas of the exposing surface are located, in an absolute or relative sense, just where they would be expected to be located according to the geometry of the system, and according to the inven ⁇ tion this can be under steady control, with associated operation of actuators for displacing the partial areas where this is possible, and/or dynamical adjustment of the irradiation for compensating for the undesired ef ⁇ fect of a displaced location of the partial area as actually irradiated.
  • the means used for detection of e.g. the exact configuration of the surface to be exposed should not necessarily be in operation during the scanning itself, as they may well be adapted so as to complete their detection movement during an initial phase of the opera ⁇ tion, with an associated recording of the produced flow of measuring results in a memory unit, which will there ⁇ after hold full information about the required adjust ⁇ ments during one or perhaps more successive working operations.
  • Fig. 1 is a schematic length sectional view of a unit according to the invention
  • Fig. 2 is an end view thereof
  • Fig. 3 is a perspective view of a modified drum support
  • Fig. 4 is an end view thereof.
  • Figs. 5 and 6 are interrelated side and end views of another scanning unit
  • Fig. 7 is a schematical side view illustrating correction means for an operational displacement.
  • the unit shown in Figs. 1 and 2 comprises in a well known manner a spinner housing 2, in which there is provided a fast rotating spinner 4 having at its front end a centrally arranged mirror or prism 6 adapted to receive a central laser beam 8 from a laser beam genera ⁇ tor, this beam passing through a controlled focusing unit 10 and a modulator 12, which, controlled by a com ⁇ puter, operates as a on/off switch unit for the light beam.
  • the spinner housing 2 is sur ⁇ rounded by a cylinder or drum 16, on the inner side of which can be mounted a film or another light sensitive plate or sheet member 18 for graphical use.
  • This member which extends along only a part of the inner periphery of the drum, is held tightly against the inner side of the drum, normally by means of a vacuum applied from outside.
  • the spinner housing is axially movable relative to the drum, and the mirror or prism 6 will serve to deflect the light beam 8 radially against the film 18.
  • the radial light beam or working beam designated 20 will describe a screw-line on the film 18, and when the pitch of the screw-line corresponds to the thickness of the working line the result will be a co ⁇ herent exposure of the film surface, with the exposure pattern determined by the computer 14.
  • the drum 16 is axially split as shown at 22 in Fig. 2, and the spinner housing 4 is mounted on a support 24 extending through this split for connection with a non-illustrated carrier slide that is operable to effect the said axial displacement of the spinner relatively to the rigidly mounted drum 16.
  • a rotating measuring rotor 26 consisting of a hub portion 28 having outwardly projecting radial arms 30, which at their outer ends carry a cylindrical shell 32 extending along a partial length of the outer drum 16, with its front end portion projecting in front of the spinner housing to a position slightly behind the working beam 20.
  • the measuring rotor is driven at an angular velocity much lower than that of the spinner.
  • a pair of distance measuring units 34 e.g. in the form of well known radiation based sensors, which can currently detect the distance to the inner side of the drum or rather to the inner side of the film 18.
  • the sensors 34 are connected to a microprocessor 36, i.e. via contact rings not shown.
  • a light sensor 38 adapted to receive a light beam 40 deflected radially from the spinner 4 in parallel with the working beam 20, this being enabled by the mirror 6 being slightly trans ⁇ parent, such that the beam 8 is carried further in a weak beam reaching an extra mirror or prism 42, which will then produce the radial beam 40.
  • this beam will always be exactly parallel with the working beam 20, and it will hit the sensor 38 by each revolution of the spinner 40, subject to the beam 8 being switched on, and it will be unimportant that the sensor 38 by each beam passage has been moved very slightly due to the slow rotation of the measuring rotor 26.
  • the sensor 38 is not a light intensity gauge, but a beam direction gauge which will detect whether the re ⁇ ceived beam 40 is exactly perpendicular to the mounting plane of the sensor, respectively whether the received beam is located exactly at the middle of the sensor.
  • the beam 40 will not be deflected entirely per ⁇ pendicularly from the axis of the system, and at least in certain positions of the measuring rotor this will imply that the beam 40 moves forwardly or rearwardly from the middle of the sensor 38, which can thereby detect the obliqueness of the beam 8.
  • the sensor 38 is connected to the microprocessor 36.
  • the spinner housing 2 is mounted in a non-illustrated support by intermediate of a number of piezo ceramic actuators 44 which at the respective front and rear ends of the spinner housing may be operated to effect a small transverse displacement of these housing ends by means of electrical control signals from the microprocessor 36.
  • the laser generator 9 may be supported in a similar manner, such that also the centering and beam direction of this unit can be controlled dynamically within an estimated required range. In both cases the required displacements will be so small that they can be effected by the use of simple piezo elements 44.
  • the measuring rotor 26, via the outer sensors 34 will control the centered location of the spinner 4 in the outer drum during the on-going, relatively slow axial movement of the spinner. Should a section of the cylinder change the direction or the location of the center axis this will quite rapidly be sensed by the sensors 34, which will then, via the micro processor 36, affect the elements 44 to adjust the spinner according to the changed circum ⁇ stances. If or when an associated wry or off-centered incidence of the laser beam 8 occurs this will be de ⁇ tected by the sensor 38, whereby the micro processor causes the laser generator 9 to change its position for correction of the beam incidence so that this will again be correct for achieving a perpendicular incidence of the working beam 20 on the film 18.
  • the spin ⁇ ner position may be adjusted by a corresponding, current adjustment of the guiding means for the spinner housing.
  • the focusing unit 10 should focus the laser beam exactly in the working point on the exposure surface, this being controlled auto ⁇ matically via the computer 36. According to the inven ⁇ tion it is possible to improve this control based on the additional changes of distance as detected by the sensor 34.
  • the irregularities that may occur when the drum 16 is not shaped with extreme accuracy may also be due to local deviations from the whole-circular cross-section of the drum, whereby as mentioned the problem will arise that the single pixels will appear with mutually dif ⁇ ferent lengths, while for a perfect reproduction they should appear with constant length.
  • the dynamic adjust ⁇ ment possibilities as discussed above will thus only amount to half a solution of the discussed problem, i.e. no complete solution, and it is therefore equally im ⁇ portant that also this problem be solved.
  • the sensors 34 for detecting whether in the generally cen ⁇ tered position of the spinner housing there are any differences in the distance between the sensors 34 and the film 18 during the revolutions of the measuring rotor 26.
  • detector means 45 are provided for detecting the an ⁇ gular position of the spinner relative to the housing, and via a wire 46 these means are connected to a control unit 48 for the duration of the pixel pulses.
  • the unit 48 is connected with the micro processor 36, and it is achievable hereby that a periodic variation of the distance out to the film 18 as detected by one of the sensors 34 will produce a corresponding change of the pixel length by the beam sweeping of the film, such that the neighbouring pixel lengths will be quite uniform anyway.
  • the pixel length will be increased where the drum radius is being increased and decreased where the drum radius is decreasing.
  • the invention comprises further adjustment means for alternative or supplementing control of the center ⁇ ing of the spinner relative to the cylinder 16 and par ⁇ tial areas thereof, namely means for a controlled mechanical deformation of the cylinder itself depending of variations in the measuring results from the distance sensors 34.
  • control of the center ⁇ ing of the spinner relative to the cylinder 16 and par ⁇ tial areas thereof namely means for a controlled mechanical deformation of the cylinder itself depending of variations in the measuring results from the distance sensors 34.
  • the effect of the elements 52 is not bound to be a local deformation of the cylinder 16, as another result may be a pure moving of the entire cylinder cross-section relative to the stronger outer cylinder 50 for achieving a perfect centering.
  • the cylinder unit 16, 50 is supported by a support 54, which, optionally, can be slidably arranged on rails 56 for carrying out a desired axial displacement during the scanning, namely if this movement is to be made by the cylinder and not by the spinner.
  • the sup ⁇ port may have an extended length and that in the surface of the groove 58, in which the cylinder unit is sup ⁇ ported, holes 60 can be provided. This refers to the cylinder being slidably held in the groove 58 in a still-standing block 54 and to the holes 60 being blow-out holes for compressed air, such that the cyl ⁇ inder will be carried without friction on an air bear ⁇ ing.
  • FIGs. 5 and 6 another scanner principle is il ⁇ lustrated, where the exposure surface, e.g. in the form of an offset film 64, is mounted in a well-known manner on the outer side of a drum 66, which, by driving means not shown, is rotated with a speed of e.g. 1000-2000 r.p.m.
  • a drum 66 which, by driving means not shown, is rotated with a speed of e.g. 1000-2000 r.p.m.
  • a guiding rail for a slide 68 carrying an inclined mirror 70 which receives a laser beam 8 and deflects this beam ortho ⁇ gonally onto the drum surface as a focused working beam 20.
  • the slide is driven along the drum by means of a spindle (not shown) .
  • a distance detector 72 at either end of the slide, and two corresponding sensors 74 are placed on a carrier arm 76 in positions spaced 90° from the slide 68 (Fig. 6) .
  • These sensors are connected in the system just as the sensors 44 in Fig. 1, whereby they can control the same kind of corrections as specified above.
  • the drum can be produced less accurately than otherwise.
  • the applied means for effecting the axial displacement operate with a highly even speed.
  • a screw spindle is used, and it can well be rotated with even speed, but it should be worked extremely accurately for translating the rotation into an even displacement of the driven elements.
  • the screw spindle is designated 80 and an associated motor 82.
  • On the spindle is mounted a slide, e.g. the slide 68 of Fig. 5, this slide having a nut member 84 in threaded engagement with the spindle.
  • the nut member 84 is axially connected with the slide 68 through a number of piezo electrical actuators 86 connected to a servo con ⁇ trol unit 88.
  • a laser interferometer 90 is mounted for momentary detection of the moving velocity of the slide 68 by means of a detector beam 92 and for reading in the velocity into the control unit 88.
  • the control unit 88 may adjust the speed of the motor 82, but because the reaction time of the motor is relatively long care is taken for arranging a more rapid or instantaneous acti ⁇ vation of the actuators 86 for displacing the slide in the relevant direction relative to the nut member 84.

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  • Engineering & Computer Science (AREA)
  • Multimedia (AREA)
  • Signal Processing (AREA)
  • Exposure And Positioning Against Photoresist Photosensitive Materials (AREA)

Abstract

Lors de l'analyse des cylindres à graphiques, le cylindre doit être très précis et l'unité d'analyse doit être réglée de manière très précise. On a mis au point divers procédés de réglage purement dynamiques permettant une réduction sensible de la précision exigée et donc une diminution du coût des unités d'analyse.
PCT/DK1991/000252 1990-08-29 1991-08-29 Procede de reglage d'unites d'analyse graphique et unite d'analyse munie d'un dispositif de reglage Ceased WO1992004661A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DK207090A DK207090D0 (da) 1990-08-29 1990-08-29 Fremgangsmaade og apparat til udfoerelse af tromlescanning
DK2070/90 1990-08-29

Publications (1)

Publication Number Publication Date
WO1992004661A1 true WO1992004661A1 (fr) 1992-03-19

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Application Number Title Priority Date Filing Date
PCT/DK1991/000252 Ceased WO1992004661A1 (fr) 1990-08-29 1991-08-29 Procede de reglage d'unites d'analyse graphique et unite d'analyse munie d'un dispositif de reglage

Country Status (3)

Country Link
AU (1) AU8446291A (fr)
DK (1) DK207090D0 (fr)
WO (1) WO1992004661A1 (fr)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2298493A (en) * 1995-03-02 1996-09-04 Eastman Kodak Co Floating projection head for high speed writer.
WO1996034747A1 (fr) * 1995-05-02 1996-11-07 Krause Danmark A/S Appareil d'exposition a laser
DE19516154A1 (de) * 1995-05-03 1996-11-14 Hell Ag Linotype Vorrichtung zur Positionserfassung von rotierenden Objekten
EP0679520A3 (fr) * 1994-04-29 1998-06-03 Eastman Kodak Company Système de lentilles à positions multiples pour l'exposition des moyens photosensibles dans une imprimante rotative
DE19820630A1 (de) * 1998-05-08 1999-11-11 Heidelberger Druckmasch Ag Vorrichtung zur Positionserfassung von rotierenden Objekten

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3521993A1 (de) * 1984-06-21 1986-01-02 Iwatsu Electric Co., Ltd., Tokio/Tokyo Verfahren zur kontrolle von druckplatten-positionen und -fehlern
EP0327019A2 (fr) * 1988-02-01 1989-08-09 Dainippon Screen Mfg. Co., Ltd. Film formant masque pour la prémise en train
DK162469B (da) * 1989-10-13 1991-10-28 Krause Biagosch Gmbh Fremgangsmaade til fremstilling af trykplader ved hjaelp af en laserstraale

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3521993A1 (de) * 1984-06-21 1986-01-02 Iwatsu Electric Co., Ltd., Tokio/Tokyo Verfahren zur kontrolle von druckplatten-positionen und -fehlern
EP0327019A2 (fr) * 1988-02-01 1989-08-09 Dainippon Screen Mfg. Co., Ltd. Film formant masque pour la prémise en train
DK162469B (da) * 1989-10-13 1991-10-28 Krause Biagosch Gmbh Fremgangsmaade til fremstilling af trykplader ved hjaelp af en laserstraale

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0679520A3 (fr) * 1994-04-29 1998-06-03 Eastman Kodak Company Système de lentilles à positions multiples pour l'exposition des moyens photosensibles dans une imprimante rotative
GB2298493A (en) * 1995-03-02 1996-09-04 Eastman Kodak Co Floating projection head for high speed writer.
GB2298493B (en) * 1995-03-02 1998-09-02 Eastman Kodak Co Floating radiant energy projection head for high speed writer
WO1996034747A1 (fr) * 1995-05-02 1996-11-07 Krause Danmark A/S Appareil d'exposition a laser
US5909236A (en) * 1995-05-02 1999-06-01 Krause Danmark A/S Laser exposure apparatus
DE19516154A1 (de) * 1995-05-03 1996-11-14 Hell Ag Linotype Vorrichtung zur Positionserfassung von rotierenden Objekten
DE19820630A1 (de) * 1998-05-08 1999-11-11 Heidelberger Druckmasch Ag Vorrichtung zur Positionserfassung von rotierenden Objekten
US6316765B1 (en) 1998-05-08 2001-11-13 Heidelberger Druckmaschinen Device for detecting the position of rotating objects

Also Published As

Publication number Publication date
DK207090D0 (da) 1990-08-29
AU8446291A (en) 1992-03-30

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