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WO1997037272A1 - Dispositif de formation d'image - Google Patents

Dispositif de formation d'image Download PDF

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Publication number
WO1997037272A1
WO1997037272A1 PCT/GB1997/000894 GB9700894W WO9737272A1 WO 1997037272 A1 WO1997037272 A1 WO 1997037272A1 GB 9700894 W GB9700894 W GB 9700894W WO 9737272 A1 WO9737272 A1 WO 9737272A1
Authority
WO
WIPO (PCT)
Prior art keywords
radiation
light
image
output means
display
Prior art date
Application number
PCT/GB1997/000894
Other languages
English (en)
Inventor
William Alden Crossland
Anthony Bernard Davey
Vincent Glenn Geake
Ian David Springle
Paul Andrew Bayley
Original Assignee
Screen Technology Limited
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 Screen Technology Limited filed Critical Screen Technology Limited
Priority to AU22988/97A priority Critical patent/AU2298897A/en
Priority to EP97915552A priority patent/EP0890130A1/fr
Publication of WO1997037272A1 publication Critical patent/WO1997037272A1/fr

Links

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41J—TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
    • B41J2/00—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed
    • B41J2/435—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed characterised by selective application of radiation to a printing material or impression-transfer material
    • B41J2/447—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed characterised by selective application of radiation to a printing material or impression-transfer material using arrays of radiation sources
    • B41J2/45—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed characterised by selective application of radiation to a printing material or impression-transfer material using arrays of radiation sources using light-emitting diode [LED] or laser arrays
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/1333—Constructional arrangements; Manufacturing methods
    • G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/1333—Constructional arrangements; Manufacturing methods
    • G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
    • G02F1/1336—Illuminating devices
    • G02F1/133617—Illumination with ultraviolet light; Luminescent elements or materials associated to the cell
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/1333—Constructional arrangements; Manufacturing methods
    • G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
    • G02F1/13356—Structural association of cells with optical devices, e.g. polarisers or reflectors characterised by the placement of the optical elements
    • G02F1/133562—Structural association of cells with optical devices, e.g. polarisers or reflectors characterised by the placement of the optical elements on the viewer side

Definitions

  • the invention is concerned with displays and related devices where input light is modulated to affect a secondary output.
  • One such type of device is described in WO 95/27920 (Crossland et al) , which describes the use of LC panels to modulate continuous UV illumination incident on phosphors which consequently emit visible light.
  • These displays have excellent viewing angle characteristics by comparison with standard LC displays where the light passing through the liquid crystal is the light reaching the viewer.
  • TFT colour displays since they are believed to be more efficient than TFT colour displays, they can produce greater visible light power than TFTs making them viewable in higher levels of ambient light.
  • they still suffer from the problem intrinsic to emissive displays that the output light power must be increased as ambient light increases, and hence the power consumption increases.
  • an image-forming device including a source of radiation, a means of modulating this radiation according to the image to be formed, and an output means towards which the modulated radiation is directed and whose reflective or light-absorptive properties are altered when it receives the radiation.
  • the alteration may be permanent, giving a function analogous to a printer, or temporary, giving a display function.
  • the invention is concerned with a method of displaying data, in which the data are represented by a material whose reflective or absorptive characteristics are altered by the selective application of incident radiation.
  • the invention is also directed to a display unit having a screen which can be removed from the unit and stores the latest displayed image .
  • the output means is generally a sheet of material, or a substrate coated with such a material, which reflects a different amount or portion of the incident light according to whether it has been exposed to suitable radiation, which for most practical purposes will be light of shorter wavelengths, such as UV light. The effect is that the material changes for instance from transparent to dark or coloured, or vice versa, or from one colour to a different colour.
  • photochromic dyes Various materials, known as photochromic dyes, exist whose absorption characteristics in the visible spectrum can be changed by exposure to specific narrow ⁇ band activation light. This narrow-band light need not be within the spectrum generally referred to as ultra ⁇ violet, but in many cases this is so; hence the term UV will be used here to describe the light used to activate the photochromic materials.
  • Pilkingtons manufacture a range of such materials; see for instance US 4913544 and 4851530. They are sold by James Robinson Ltd. of Huddersfield, UK under the name Reversacols, and are described as switching between a nearly transparent and a coloured state.
  • a well known usage of photochromic materials is in sunglasses which change their degree of tint according to the intensity of ambient sunlight. These materials can be tailored to have various 'on' and 'off colours, though sunglasses are generally brown or green when on and transparent when off .
  • the modulating means is most naturally an addressable liquid-crystal layer, and for a display the reflecting substance can be applied in the form of dots on the glass cover of the LC layer.
  • These dots can be made of a photochromic dye in a suitable carrier, such as a polymeric film. Since photochromic materials are usually absorptive dyes rather than reflective it will normally be desirable to provide a white background; this can be afforded by a scattering means below or incorporated with the dye.
  • the scattering means is represented by a roughening of the top surface of the glass cover of the liquid crystal. Alternatively the scatterer could be below the entire assembly as in a known transflective display, though here the usual parallax problems are presen .
  • Fig. 1 is a schematic diagram of an embodiment of the invention as a display
  • Fig. 2 shows an embodiment incorporating a printer
  • Fig. 3 shows a variation of Fig. 1; and Fig. 4 shows a further display embodiment.
  • the display shown in Fig. 1 is broadly similar to those in WO 95/27920.
  • Near ultra-violet (UVA) light 20 is directed in collimated fashion from the rear towards a liquid-crystal cell which acts as a modulator and can be of conventional construction.
  • the liquid-crystal material 1 is sandwiched between glass layers 5 and is divided into pixels by orthogonal electrode arrays 3.
  • orthogonal electrode arrays 3 For a typical LC, for instance of the twisted-nematic type, the cell would also contain polarisers, but for simplicity these are not shown.
  • This photochromic material takes the place of the emissive phosphors in UVLCDs.
  • Above the photochromic material though not shown is a UV filter to prevent leakage of
  • UV light and unwanted activation by ambient UV light are unwanted UV light and unwanted activation by ambient UV light.
  • the UV light is modulated by the LC material, and in those pixels where it is allowed to pass it strikes the photochromic material which then changes colour, as shown at 11a.
  • the viewed display can then be read when front-lit by ambient light 30.
  • the background colour is provided by reflection from the body colour (probably black or white) of the photochromic material; to this end the photochromic material is made up of a carrier, a pigment material making up the background colour, here white, and the photochromic substance or dye itself.
  • the carrier can be of plastics, such as polystyrene, or fibrous, in the manner of paper.
  • FIG. 3 illustrates an alternative way of arranging the photochromic material and the background layer.
  • the background layer 17 can be a layer applied to the glass cover 5 of the LC cell, or alternatively and particularly simply it can be formed by a frosted surface of this glass.
  • the background layer 17 is required to scatter the ambient light 30 so that the viewer sees a plain background and not the structure of the LC cell below.
  • the layer 17 will therefore unavoidably also scatter some of the incoming UV light 20, though a certain degree of "tuning" is possible so the UV is scattered less than visible radiation. This UV scattering is shown at 20a.
  • FIG 4 illustrates a further variant of the invention which dispenses with the need to produce directed backlighting 20 by a construction analogous to the known "transflective" scheme in which a liquid crystal display is visible by both reflected light and back-lighting.
  • a totally internally reflecting (TIR) backplane 30 is arranged in contact with and under the liquid-crystal cell 1 which is of the scattering type. UV light 20 is input from lamps 32 from the side of the plane 30 and remains within it by TIR while the liquid crystal is not addressed.
  • a white or other coloured background 34 is placed behind the TIR plane 30.
  • the photochromic dots 11 here are transparent and are mounted on a transparent substrate 12 held parallel to the LC cell by spacers 14 as shown, with a small air gap.
  • the air gap is necessary to ensure that light stays within the backplane/LC assembly when the liquid crystal is not switched.
  • UV is scattered out of the TIR plane and strikes the photochromic dot 11, changing its colour.
  • the UV light could be pulsed to refresh the screen at whatever the display information rate is. On a flight or train arrivals annunciator board, for instance, this might be only one flash per minute giving a much reduced power compared with the continuous illumination required for TFTs or for phosphor UVLCDs, while overcoming problems of mechanical reliability in mechanical displays.
  • photochromic material exhibits persistence
  • various mechanisms can be used to switch the photochromic material off; either: 1. it naturally relaxes after a given period at room temperature;
  • FIG. 1 shows a further embodiment of the invention as a printer.
  • the photochromic material is made into a sheet form (or incorporated into a sheet of paper) 13 which can be detached from the front of the display. The sheet thus functions both as a display screen and as a hard copy.
  • the photochromic material could either be type 1/2 with a very long persistence
  • the system is capable of writing subtractive colours (i.e. not the RGB additive colours of emissive light) to a white screen - this could provide a form of electronic paper;
  • the unit is a screen printer, not a line printer - the whole image is addressed directly/ simultaneously as opposed to printer carriage systems when one dimension of output image is provided by the passage of paper past the printhead; and
  • the image is viewed directly and can be edited and modified until the hardcopy function is used which instantly stores the exact output on a sheet of paper or similar material.
  • the unit is portable and combined, unlike dedicated free-standing printers like the old azo-dye blueprint machines which used UV in the imaging process.
  • the hard copy can be reversible and rewriteable.
  • UV light is suitable for many embodiments as the activating radiation.
  • visible light could be used, particularly if only a monochrome display is required.
  • the cover for the photochromic material 11 would have to filter out the relevant wavelength since otherwise the ambient light would continually activate it. This is not such a problem for the UV version since most glasses and plastics will block UV.
  • the photochromic material layer 11 can be within the liquid-crystal cell. This reduces any collimation requirements.

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  • Physics & Mathematics (AREA)
  • Nonlinear Science (AREA)
  • Optics & Photonics (AREA)
  • Mathematical Physics (AREA)
  • Chemical & Material Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • General Physics & Mathematics (AREA)
  • Health & Medical Sciences (AREA)
  • General Health & Medical Sciences (AREA)
  • Toxicology (AREA)
  • Liquid Crystal (AREA)
  • Devices For Indicating Variable Information By Combining Individual Elements (AREA)

Abstract

Dispositif de formation d'images composé d'une source de rayonnement (20), par exemple des U.V., d'un moyen tel qu'une cellule de cristaux liquides (1) permettant de moduler ce rayonnement en fonction de l'image à former et d'un support de sortie (11) vers lequel le rayonnement modulé est orienté et dont les propriétés de réflexion et d'absorption sont modifiées à la réception du rayonnement. Une matière photochromique, qui change de couleur sous l'influence des U.V., se prête bien comme support de sortie. La représentation ainsi obtenue peut offrir une bonne visibilité par une forte lumière ambiante. Le support de sortie peut également être présenté sous une forme amovible, le dispositif jouant alors un rôle d'imprimante.
PCT/GB1997/000894 1996-03-29 1997-03-27 Dispositif de formation d'image WO1997037272A1 (fr)

Priority Applications (2)

Application Number Priority Date Filing Date Title
AU22988/97A AU2298897A (en) 1996-03-29 1997-03-27 Image-forming device
EP97915552A EP0890130A1 (fr) 1996-03-29 1997-03-27 Dispositif de formation d'image

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GBGB9606660.0A GB9606660D0 (en) 1996-03-29 1996-03-29 Image-forming device
GB9606660.0 1996-03-29

Publications (1)

Publication Number Publication Date
WO1997037272A1 true WO1997037272A1 (fr) 1997-10-09

Family

ID=10791281

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/GB1997/000894 WO1997037272A1 (fr) 1996-03-29 1997-03-27 Dispositif de formation d'image

Country Status (4)

Country Link
EP (1) EP0890130A1 (fr)
AU (1) AU2298897A (fr)
GB (1) GB9606660D0 (fr)
WO (1) WO1997037272A1 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7521159B2 (en) * 2005-03-30 2009-04-21 Xerox Corporation Multicolor electronic paper

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3744877A (en) * 1971-06-24 1973-07-10 American Cyanamid Co Dark trace display device employing uv phosphor plus photochromic resin inside the display screen which generates color by means of triplet-to-triplet absorption
US5050001A (en) * 1989-07-07 1991-09-17 Fuji Photo Film Co., Ltd. Printing system with liquid crystal shutter matrix panel
JPH05134333A (ja) * 1991-11-08 1993-05-28 Mitsubishi Electric Corp プリンタ装置
WO1995027920A1 (fr) * 1994-04-06 1995-10-19 Screen Technology Limited Ecran d'affichage

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3744877A (en) * 1971-06-24 1973-07-10 American Cyanamid Co Dark trace display device employing uv phosphor plus photochromic resin inside the display screen which generates color by means of triplet-to-triplet absorption
US5050001A (en) * 1989-07-07 1991-09-17 Fuji Photo Film Co., Ltd. Printing system with liquid crystal shutter matrix panel
JPH05134333A (ja) * 1991-11-08 1993-05-28 Mitsubishi Electric Corp プリンタ装置
WO1995027920A1 (fr) * 1994-04-06 1995-10-19 Screen Technology Limited Ecran d'affichage

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
PATENT ABSTRACTS OF JAPAN vol. 017, no. 512 (P - 1613) 14 September 1993 (1993-09-14) *

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7521159B2 (en) * 2005-03-30 2009-04-21 Xerox Corporation Multicolor electronic paper

Also Published As

Publication number Publication date
AU2298897A (en) 1997-10-22
GB9606660D0 (en) 1996-06-05
EP0890130A1 (fr) 1999-01-13

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