WO1993004444A1 - Appareil de formation d'images utilisant une lentille de grande ouverture numerique et une fibre optique - Google Patents

Appareil de formation d'images utilisant une lentille de grande ouverture numerique et une fibre optique Download PDF

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Publication number
WO1993004444A1
WO1993004444A1 PCT/US1992/006990 US9206990W WO9304444A1 WO 1993004444 A1 WO1993004444 A1 WO 1993004444A1 US 9206990 W US9206990 W US 9206990W WO 9304444 A1 WO9304444 A1 WO 9304444A1
Authority
WO
WIPO (PCT)
Prior art keywords
lens
numerical aperture
fiber
writing
radiation
Prior art date
Application number
PCT/US1992/006990
Other languages
English (en)
Inventor
Kurt Michael Sanger
John Darrell Gentzke
Original Assignee
Eastman Kodak Company
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 Eastman Kodak Company filed Critical Eastman Kodak Company
Priority to JP5504568A priority Critical patent/JPH06501898A/ja
Publication of WO1993004444A1 publication Critical patent/WO1993004444A1/fr

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Classifications

    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06K—GRAPHICAL DATA READING; PRESENTATION OF DATA; RECORD CARRIERS; HANDLING RECORD CARRIERS
    • G06K15/00—Arrangements for producing a permanent visual presentation of the output data, e.g. computer output printers
    • G06K15/02—Arrangements for producing a permanent visual presentation of the output data, e.g. computer output printers using printers
    • G06K15/12—Arrangements for producing a permanent visual presentation of the output data, e.g. computer output printers using printers by photographic printing, e.g. by laser printers
    • G06K15/1238—Arrangements for producing a permanent visual presentation of the output data, e.g. computer output printers using printers by photographic printing, e.g. by laser printers simultaneously exposing more than one point
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/04—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings formed by bundles of fibres
    • G02B6/06—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings formed by bundles of fibres the relative position of the fibres being the same at both ends, e.g. for transporting images
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06K—GRAPHICAL DATA READING; PRESENTATION OF DATA; RECORD CARRIERS; HANDLING RECORD CARRIERS
    • G06K15/00—Arrangements for producing a permanent visual presentation of the output data, e.g. computer output printers
    • G06K15/02—Arrangements for producing a permanent visual presentation of the output data, e.g. computer output printers using printers
    • G06K15/027—Test patterns and calibration

Definitions

  • This invention relates to an image forming apparatus in which radiation emitted from one or more optical fibers is imaged on a medium sensitive to that radiation by a high aperture lens.
  • a thermal printer using light emitting diodes to provide thermal energy to selectively transfer dye to a receiver to form an image.
  • a thermal printer which may be adapted for use as a direct digital color proofer with halftone capabilities.
  • This printer forms an image on a thermal print medium in which a donor element transfers a dye to a receiver element in response to a sufficient amount of thermal energy. It includes a plurality of diode lasers which can be individually modulated to supply energy to selected areas of the medium in accordance with an information signal.
  • the printer includes a printhead which includes one end of a fiber optic array having a plurality of optical fibers coupled to the diode lasers.
  • a thermal print medium is supported on a rotatable drum, and the printhead with the fiber optic array is movable relative to the drum.
  • Dye is transferred by sublimation to the receiver element as the radiation, transferred from the diode lasers to the donor element by the optical fibers is converted to thermal energy in the donor element.
  • the writing beams are presented to the apparatus in the printhead by optical fibers from their laser diodes.
  • the ends of the optical fibers are imaged on the donor medium by a high numerical aperture lens.
  • a detector is positioned outside of the moving drum surface.
  • the printhead is movable to a position in optical alignment with the detector.
  • Each laser diode is energized separately and the detector senses the illumination from the laser diode and feeds that information to an appropriate logic and control unit.
  • the logic and control unit uses that information to adjust the drive current to each laser diode. With this system the printhead can be periodically calibrated.
  • a 10-stripe gain guided laser diode was coupled to an optical fiber using a tapered fiber pigtail design.
  • Such laser diodes have a large numerical aperture by nature of the 10-stripe design.
  • the fibers are of the step index type. To obtain the largest amount of radiation from the diode, fibers having an numerical aperture of 0.40 were used. A lens was used that had an extremely high acceptance numerical aperture of approximately 0.25. With this scheme the printhead was found to have a 5% variability in output power as measured during calibration. The power variabilities are believed to be due to a sensitivity to fiber movement, diode current and temperature.
  • a 5-stripe laser diode is used with a fiber having a 0.29 numerical aperture. This is coupled with the 0.25 numerical aperture lens. Partially because of the low numerical aperture of the 5-stripe diode, this system is also more efficient than the 10-stripe diode and 0.40 numerical aperture fiber as well as being less variable in intensity.
  • both writing and calibration is done at comparable numerical apertures for the fiber and lens.
  • the lens includes a stop or other means for varying its aperture. Calibration is done with the lens at its maximum numeric aperture and the fiber at a numerical aperture not substantially more than it.
  • writing is done with the lens aperture reduced. This will add optical noise to the print as well as some variability in intensity. However, the optical noise is random and can be used in writing to overcome image and printer artifacts.
  • Fig. 1 is a perspective view of the imaging apparatus of the present invention, partially cut-away to reveal hidden portions thereof.
  • Fig. 2 is a sectional view of the writing head and lens assembly taken along line 2-2 of Fig. 1.
  • Fig. 3 is an end view of the print head assembly.
  • Fig. 4 is a plan view of an optical fiber supporting substrate.
  • Fig. 5 is a perspective schematic illustrating the relationship of the drum, calibration detector, and a portion of the printhead.
  • Fig. 6 is a side schematic illustrating the relative numerical apertures of the lens and the optical fibers.
  • a thermal printer 10 comprising a drum member 12 mounted for rotation about an axis 15 in frame member 14.
  • the drum member 12 is adapted to support a thermal print medium, not shown, of a type in which a dye is transferred by sublimation from a donor element to a receiver element as a result of heating the dye in the donor.
  • the donor element and the receiver element are superposed in relatively intimate contact and are held onto the peripheral surface of the drum member by means such as by vacuum applied to the superposed elements from the drum interior.
  • a thermal print medium for use with the printer 10 can be, for example, the medium disclosed in U.S. Patent No.
  • 4,772,582 which includes a donor sheet having a material which strongly absorbs at the wavelength of the exposing light source.
  • this absorbing material converts light energy to thermal energy and transfers the heat to the dye in the immediate vicinity, thereby heating the dye to its sublimation temperature for transfer to the receiver element.
  • the absorbing material may be present in a layer beneath the dye, or it may be admixed with the dye and is strongly absorptive to light having wavelengths in the range of 800nm - 880nm.
  • An example of a preferred embodiment of a receiver element that can be used with the present invention is disclosed in co-pending, commonly assigned EPO Application No. 91118514.8, filed October 30, 1991.
  • the receiver element disclosed therein incorporates a reflective layer which improves the efficiency of the dye transfer to the receiver element.
  • the light source is movable with respect to the drum member and is arranged to direct a beam of actinic light to the donor element.
  • the light source comprises a plurality of laser diodes which can be individually modulated by electronic signals which are representative of the shape and color of the original image, so that each dye is heated to cause volatilization only in those areas in which its presence is required on the receiver to reconstruct the color of the original object.
  • the laser diodes are mounted remotely from the drum member 12 (as shown schematically in Fig. 5), on the stationary portion of the frame 14 (Fig. 1), and each direct the light produced thereby to the input end of a respective optical fiber which extends to and transfers the light to a movable writing head 20 adjacent the drum member.
  • Each of the laser diodes is selected to produce a first beam of light having wavelengths in the range of 800nm - 880nm, and preferably predominantly at a wavelength of 830nm.
  • the writing head 20 is moveably supported adjacent drum member 12 and is mounted on a moving translator member 21 which, in turn, is supported for slidable movement on bars 22 and 24.
  • the bars 22 and 24 are sufficiently rigid that they do not sag between the mounting points at their ends and are arranged as exactly parallel with the axis of the drum member as possible.
  • the upper bar 22 is arranged to locate the writing head precisely on the axis of the drum with the axis of the writing head perpendicular to the drum axis.
  • the upper bar 22 locates the translator in the vertical and the horizontal directions with respect to the axis of the drum member.
  • the lower bar 24 locates the translator member only with respect to rotation of the translator about the bar 22 so that there is no over-constraint of the translator which might cause it to bind, chatter, or otherwise impart undesirable vibration to the writing head during the generation of an image.
  • the translator member 16 is driven by means of a motor (not shown) which rotates a lead screw 26 parallel to bars 22 and 24 to move the writing head parallel with the axis of the drum member.
  • the coupling (not shown) which connects the translator member to the lead screw is carefully chosen so that the only force imparted to the translator by the lead screw is parallel to the drum axis.
  • the writing head 20 is removably mounted on the translator member 16 so that it automatically adopts the preferred orientation with respect to the drum axis noted above.
  • the writing head is selectively locatable with respect to the translator, and thus with respect to the drum surface and axis, with respect to its distance from the drum surface, and with respect to its angular position about its own axis.
  • a pair of adjustable locating means are provided to accurately locate the writing head with respect to these two axes on the translator member 16. Only one of the adjustable locating means, a micrometer adjustment screw 25, is illustrated.
  • a torsion and compression spring 27 is provided to load the writing head against these locating means.
  • the end of the writing head 20 adjacent the drum member 12 is provided with a pair of photosensors 29 aimed at the surface of the drum member.
  • the photosensors may each include an infrared source or they may rely on an outside source of light energy.
  • the photosensors are disposed on diametrically opposite sides of the optical axis of the writing head in a fixed relationship thereto.
  • a cross section of the writing head 20 is illustrated in Fig. 2 and comprises a generally cylindrical barrel portion 50 having a flange 52 at the drum end thereof.
  • the interior of the barrel portion is arranged to accept a stationary lens barrel 54 at the writing end, containing a stationary lens 56. Only the rearmost elements of lens 56 are shown. However, it is a high aperture lens having a number of elements located in barrel 54.
  • a printhead assembly 58 is selectively oriented within and at the opposite end of the barrel from the writing end.
  • the printhead assembly comprises a tubular member selectively oriented within barrel portion 50 and contains a linear array of optical fibers which includes a fiber-supporting wafer 34 having a plurality of optical fibers 60 mounted thereon.
  • the optical fibers have a writing end 36 facing the drum member 12 at the opposite end of the barrel.
  • the optical fibers 60 extend from the end of the printhead assembly and out of the writing head barrel through a protective sheath 64 to the diode lasers (Fig.5).
  • a cup-shaped closure member 66 is arranged to mate with the flange 52 of the writing head barrel 50 and forms a housing for a focusing drive means.
  • the end of the closure member adjacent drum member 12 is provided with an axially disposed opening which is bridged by a pair of sheet flexure members, 68 and 70, mounted at the outer periphery thereof by annular plate means 72 and 74 to the closure member 66.
  • the central portions of the sheet flexure members are mounted to a movable rigid cylindrical lens housing 76 which contains moveable lens 80.
  • Lens 80 is movable for focusing by a focus detection system which is not germane to this invention and will not be described in detail.
  • the fiber optic array (see Figs. 2 and 3) comprises a plurality of fibers 60 which are each connected to a respective, remotely mounted diode laser (Fig. 5).
  • the diode lasers can be individually modulated to selectively project light from the writing end 36 of the optical fibers through the lens assembly, consisting of stationary lens 56 and movable lens 80, onto the thermal print medium carried by the drum member 12.
  • the fiber optic array can be of the type shown in Figure 3 and comprises optical fibers 60 which are supported on the substrate 34.
  • the array may be of the type shown in co-pending, commonly assigned U.S. Application Serial No. 07/451,656, filed December 18, 1989.
  • Each of the optical fibers includes a jacket, a cladding, and a core, as is well known in the art.
  • the fibers extend from the laser diodes to the array and are mounted in sets of grooves 100 (Fig. 4) which are formed in the substrate 34 so that the fibers at the writing end 36 are disposed substantially parallel and adjacent to each other in very close proximity, with the ends disposed in a common plane perpendicular to ' the fiber axes.
  • the substrate 34 is disposed in the tubular member of the printhead assembly 58.
  • the tubular member is provided with a keyway 59 which mates with a corresponding key (not shown) on the inner surface of barrel portion 50 so that the orientation of the linear array 60 is at a preselected angle R with respect to the drum axis 15.
  • the determination of this relationship is relatively simply achieved with the present construction inasmuch as a visible line 61 is provided on the drum surface which is carefully fabricated to be parallel with the drum axis. Accordingly, when the photosensors 29 both detect line 61 simultaneously, the writing head has the proper angular orientation to provide the desired angle of the linear array with respect to the drum axis.
  • Adjustment of the angular positioning of the writing head is equally easy to obtain.
  • Hold down clamps 102 which lock the writing head 20 on the translator member 16, are loosened, and the micrometer adjustment screw 25 is adjusted against a stop on the translator member to rotate the head member against the force of the torsion spring 27, or to permit the torsion spring to rotate the writing head in the opposite direction, should that be necessary.
  • the photosensors 29 both simultaneously detect line 61, which may be accomplished when the drum is either moving or stationary, with or without the writing element disposed thereon, the desired angle R between the linear array and the drum axis is achieved.
  • the focus detection system utilizes a second array of optical fibers 62 mounted on the opposite surface of the substrate 34 with respect to the writing array 60.
  • Figs. 5 and 6 best illustrate the invention.
  • drum or drum member 12 is shown with a portion of printhead 20 aligned with a donor and receiver combination 200.
  • Printhead 20 is supplied with illumination from laser diodes 111 which are connected by fibers 60 to the printhead.
  • the printhead moves slowly in a direction parallel to the axis of drum 12 while the drum is rotated rapidly to helically scan the drum as described with respect to Figs. 1 and 2.
  • the output of the laser diodes and the fibers varies substantially over time. It is necessary that they be regularly recalibrated. This is accomplished by moving printhead 20 to the left as seen in Fig.
  • each of laser diodes 111 is sequentially turned on and its output at the detector 210 is measured. This measurement is fed back through the logic and control of the apparatus and is used to adjust the driving current for each laser diode. This calibration allows the outputs of the different fibers to be accurately balanced and is important for highest image quality.
  • a printhead constructed with illumination from 10-stripe laser diodes emitting at approximately 830nm and fed into optical fibers having numerical aperture of 0.40 exhibited an excessive amount of noise in the calibration process. This was determined to be due to the use of a lens which had a lower numerical aperture than the optical fibers. For example, using a lens having a numerical aperture of 0.25 a relatively intense writing beam was produced out of a fiber having a numerical aperture of 0.40. However, it was difficult to balance the driving currents for the laser diodes to achieve uniformity between the projected spots.
  • a step index fiber with a numerical aperture of 0.29 was used in combination with a 5-stripe diode. Because of efficiency between the lower numerical aperture fiber and the 5-stripe diode this combination was more efficient than the earlier printhead. However, more importantly, the noise was substantially reduced which made it much easier to balance the system during calibration. We believe this result is due to the fact that with the numerical aperture of the fiber not being substantially above that of the lens virtually all of the radiation emitting from the fiber is passed on by the lens to the detector 210. This is illustrated in Fig. 6 in which the acceptance angle 216 of the lens 56 is shown to correspond with the emission angle 206 of the fiber 60.
  • This aspect is much more important for calibration than it is for writing since calibration determines the basic balance of the printhead.
  • the increased noise is not as harmful to the image and, in fact, may be useful in a system prone to visible image artifacts. The noise, being random, will mask the image artifact.
  • an adjustable aperture 230 can be used to reduce the numerical aperture of lens 56 during writing, while the entire aperture of the lens is used during calibration. This embodiment is useful in a system in which a major problem is produced by image artifacts. It would not ordinarily be preferred since it involves reducing the intensity of the image creating radiation during writing. It would not use the full capability of the lens during writing.

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  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • General Engineering & Computer Science (AREA)
  • Theoretical Computer Science (AREA)
  • Electronic Switches (AREA)
  • Printers Or Recording Devices Using Electromagnetic And Radiation Means (AREA)

Abstract

Un appareil de formation d'images comprend une pluralité de diodes à laser (111) qui fournissent une source de rayonnements d'écriture. La sortie de chaque diode à laser est amenée à l'aide d'une fibre optique (60) à une tête imprimante dans laquelle une lentille (56) ayant une grande ouverture numérique met en image les terminaisons des fibres sur un support sensible. L'appareil possède également un mode de calibrage suivant lequel la sortie de chaque fibre est projetée individuellement sur un détecteur (210). La réponse du détecteur est utilisée pour équilibrer le courant d'attaque pour les sources à laser afin d'obtenir une sortie équilibrée de la tête imprimante. L'ouverture numérique des fibres est choisie de sorte qu'elle n'est pas sensiblement plus grande que l'ouverture numérique d'acceptation de la lentille, au moins pendant le calibrage, réduisant ainsi sensiblement le bruit qui affecte un tel calibrage.
PCT/US1992/006990 1991-08-23 1992-08-20 Appareil de formation d'images utilisant une lentille de grande ouverture numerique et une fibre optique WO1993004444A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP5504568A JPH06501898A (ja) 1991-08-23 1992-08-20 高い開口数のレンズと光ファイバとを用いた画像形成装置

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US74924191A 1991-08-23 1991-08-23
US749,241 1991-08-23

Publications (1)

Publication Number Publication Date
WO1993004444A1 true WO1993004444A1 (fr) 1993-03-04

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PCT/US1992/006990 WO1993004444A1 (fr) 1991-08-23 1992-08-20 Appareil de formation d'images utilisant une lentille de grande ouverture numerique et une fibre optique

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EP (1) EP0554433A1 (fr)
JP (1) JPH06501898A (fr)
WO (1) WO1993004444A1 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7728859B2 (en) 2005-09-26 2010-06-01 Hewlett-Packard Development Company, L.P. Optical printhead

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP4721157B2 (ja) * 2005-03-09 2011-07-13 国立大学法人金沢大学 レーザー光を用いた発色方法及び発色装置
DE102018108863A1 (de) 2018-04-13 2019-10-17 Wafios Aktiengesellschaft Biegevorrichtung für längliche Werkstücke

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4560999A (en) * 1983-01-11 1985-12-24 Canon Kabushiki Kaisha Printer head and electrophotographic printer utilizing the same
WO1990000294A1 (fr) * 1988-07-01 1990-01-11 Automatisme Et Robotisme Appliques (A.R.A.) Procedes et imprimantes laser pour imprimer des caracteres a grande cadence
EP0424174A2 (fr) * 1989-10-20 1991-04-24 Minnesota Mining And Manufacturing Company Production d'images utilisant une rangée de diodes électroluminescentes

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4560999A (en) * 1983-01-11 1985-12-24 Canon Kabushiki Kaisha Printer head and electrophotographic printer utilizing the same
WO1990000294A1 (fr) * 1988-07-01 1990-01-11 Automatisme Et Robotisme Appliques (A.R.A.) Procedes et imprimantes laser pour imprimer des caracteres a grande cadence
EP0424174A2 (fr) * 1989-10-20 1991-04-24 Minnesota Mining And Manufacturing Company Production d'images utilisant une rangée de diodes électroluminescentes

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
IBM TECHNICAL DISCLOSURE BULLETIN. vol. 25, no. 7B, December 1982, NEW YORK US pages 3814 - 3817 M. JOHNSON ET AL. 'Compact optical scanner for optical facsimile and optical printing' *
PATENT ABSTRACTS OF JAPAN vol. 9, no. 87 (M-372)(1810) 17 April 1985 & JP,A,59 214 671 ( MATSUSHITA DENKI SANGYO KK. ) 4 December 1984 *

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7728859B2 (en) 2005-09-26 2010-06-01 Hewlett-Packard Development Company, L.P. Optical printhead

Also Published As

Publication number Publication date
JPH06501898A (ja) 1994-03-03
EP0554433A1 (fr) 1993-08-11

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