WO1998052359A1 - Systeme d'affichage - Google Patents

Systeme d'affichage Download PDF

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Publication number
WO1998052359A1
WO1998052359A1 PCT/GB1998/001396 GB9801396W WO9852359A1 WO 1998052359 A1 WO1998052359 A1 WO 1998052359A1 GB 9801396 W GB9801396 W GB 9801396W WO 9852359 A1 WO9852359 A1 WO 9852359A1
Authority
WO
WIPO (PCT)
Prior art keywords
display
screen
light
excitation light
modulated
Prior art date
Application number
PCT/GB1998/001396
Other languages
English (en)
Inventor
William Alden Crossland
Anthony Bernard Davey
Vincent Glenn Geake
Ian David Springle
Timothy Martin Coker
Original Assignee
The Secretary Of State For Defence
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 The Secretary Of State For Defence filed Critical The Secretary Of State For Defence
Priority to EP98921619A priority Critical patent/EP0981911A1/fr
Priority to AU74406/98A priority patent/AU7440698A/en
Publication of WO1998052359A1 publication Critical patent/WO1998052359A1/fr

Links

Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N9/00—Details of colour television systems
    • H04N9/12—Picture reproducers
    • H04N9/31—Projection devices for colour picture display, e.g. using electronic spatial light modulators [ESLM]
    • H04N9/3129—Projection devices for colour picture display, e.g. using electronic spatial light modulators [ESLM] scanning a light beam on the display screen
    • 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
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N9/00—Details of colour television systems
    • H04N9/12—Picture reproducers
    • H04N9/31—Projection devices for colour picture display, e.g. using electronic spatial light modulators [ESLM]
    • H04N9/3191—Testing thereof
    • H04N9/3194—Testing thereof including sensor feedback
    • 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
    • G02F2202/00—Materials and properties
    • G02F2202/14—Materials and properties photochromic
    • 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
    • G02F2203/00—Function characteristic
    • G02F2203/34—Colour display without the use of colour mosaic filters

Definitions

  • the invention is concerned with displays, particularly with liquid-crystal displays (LCDs) of the photoluminescent LCD or PLLCD type, that is to say ones in which excitation light, usually in the near-visible ultra-violet, is modulated by a liquid-crystal layer to impinge upon an output layer or screen, which may be made of phosphor dots or pixels.
  • LCDs liquid-crystal displays
  • PLLCDs Various architectures for PLLCDs have been proposed, in which the location of the output material which converts the UV to visible light varies. In some cases this material may actually be within the LC cells (see US-A-4830469 (US Philips)), in other cases, e.g. WO 95/27590 (Crossland et al) or EP-A1-0522910
  • the material is on the front of the cell (the normal layout, possibly with a polariser in between) , and in others the material is mounted on a separate screen optically separated from the cell (e.g. in EP-A-185495 (Canter) or other TIR systems, where the separation is necessary to ensure optical decoupling of the excitation light) .
  • a separate screen optically separated from the cell e.g. in EP-A-185495 (Canter) or other TIR systems, where the separation is necessary to ensure optical decoupling of the excitation light.
  • the phosphor material becomes more distant from the LC shutter, a greater degree of collimation is required of the light emerging from the LC cell in order to avoid crosstalk.
  • This material can be of various types, such as fluorescers which emit a visible wavelength solely whilst being excited, phosphors which emit visible wavelengths during and for a time after excitation, and photochromies which change their absorption characteristics during and (for a time) after excitation.
  • the invention concerns a display device including: a liquid-crystal modulator comprising liquid-crystal or other optical elements adapted to modulate activating light, a screen having display elements activatable by ' the activating light, and a projection means for directing the modulated light from the liquid-crystal elements across free space and on to the corresponding elements on the screen.
  • a display element which may be of phosphor material though photochromies are conceivable, are moved away from the LC module to form a free-standing screen the display becomes what is known as a projection display, where the screen is large in comparison to the LC layer. In this case the phosphors are on the viewing screen, and the UV light is projected onto it.
  • the screen is viewed either from the side from which the UV is incident, or from the far side .
  • An advantage of this scheme is that the image is projected by a single projection head working at a narrow range of wavelengths, rather than the three projection heads at relatively broad wavelength bands (R,G,B) or a single projection head with a full visible spectrum colour image.
  • the optics, especially in the projection head are not affected by chromatic abberation and can therefore be simpler than in prior art devices, such as those in which light modulated by a liquid crystal is projected onto a reflective screen, which is then viewed by the audience .
  • the screen for such a projection display preferably includes an additional layer or layers to improve the efficiency by reflecting forwards (towards the viewer) the visible light emitted backwards that would otherwise be lost. Simplistically this would increase the efficiency of the overall display system by up to 100%. Depending on the configuration of the display, that is, rear or front projection, different types of reflecting layer would be required.
  • the liquid-crystal display preferably also includes a source of collimated monochromatic light. This may be a laser, or a UV tube and a suitable collimator .
  • the display may in one embodiment have a single modulating cell, or at least a subset of the total number of pixels of the screen, such as one line, in which case the projection head scans the modulated light across the screen.
  • a single cell raster- scanning would be used, and for a line of cells a simple vertical scan suffices.
  • a particularly powerful source of monochromatic light, such as a laser, is required in this version of the invention.
  • a very rapidly modulating liquid crystal should be used, such as a ferroelectric, or else a different kind of modulator such as an acousto-optic modulator.
  • the modulator should have a low absorption in its transmissive state, and so be less likely to overheat.
  • a cholesteric- mirror liquid-crystal arrangement would be suitable here. It is also preferable in this version to use a true phosphor, which emits light for a short period after the excitation has finished.
  • the display can have a modulator with a plurality of liquid-crystal cells each separately modulating the monochromatic light.
  • the whole screen, or a substantial part of it, can thus be simultaneously illuminated without the need to scan the modulated light.
  • a feedback system is advantageously provided in order to align the system.
  • the system can comprise a series of reflective points on the screen, the reflections from which are detected at the projector and the projecting head adjusted accordingly.
  • the distance from the projection head to the screen also needs to be accurately controlled, or at least determined, and a system of dots may be provided to range the screen, which may be the same as the reflective dots used for alignment.
  • the projection may be from either in front of or behind the screen.
  • the monochromatic activating light can be short-wavelength visible, so as to avoid any concerns, however unjustified, about safety; visible- light excitation of phosphor is described for instance in PCT/GB 97/878.
  • the projection arrangement may be behind the screen.
  • the screen may block the monochromatic light, which allows the frequency of the light to be chosen freely; it may be for example UV light, especially UVA.
  • the liquid-crystal display has a projector 1 and a screen 3. The audience sits on the other side of the screen 3 from the projector 1.
  • the projector 1 has a high-intensity source 11 of essentially monochromatic UV light at a suitable wavelength, such as 365 nm, which is widely available, or (preferably) 388 nm, which is passed through a collimator 13 to provide collimated light.
  • a suitable wavelength such as 365 nm, which is widely available, or (preferably) 388 nm, which is passed through a collimator 13 to provide collimated light.
  • the collimated light then passes through a liquid- crystal cell 15 that modulates the light.
  • a cholesteric liquid crystal is used with circularly polarised light, as described in WO 97/05520.
  • the light then passes through the projection head 17.
  • the projection head 17 diverges the collimated light in a predetermined manner. Both the precise direction of projection and the amount of divergence are controllable by a controller 23 connected to a video camera 21, as explained below.
  • the light is then incident on a screen 3.
  • the screen is made of a material that is opaque to ultraviolet light at the wavelength used, but transparent to visible light.
  • the screen 3 is approximately 2 m wide by 1.3 m high.
  • a large number of phosphor dots 31 are provided on the interior (projector-side) surface of the screen 3, arranged in groups of three phosphor dots, each group having one phosphor dot that emits red light when hit by the UV light, one phosphor dot that emits blue light and one phosphor dot that emits green light.
  • the phosphor dots may be made of standard phosphors, for example those described in the aforementioned patent US-4830469.
  • the screen 3, in this example, has 625 rows of 1000 groups of phosphor dots: each group covers an area of approximately 2 mm by 2 mm.
  • the screen 3 also has four highly reflective points 33 arranged on the projector side of the screen 3 for alignment purposes, preferably on the periphery so as no to interfere with the image.
  • the light from the projection head must be very accurately aligned with the individual pixel on the screen. In a rigid system this could be achieved by manual adjustment, but in this embodiment it is done by means of adaptive optics.
  • the camera 21 records an image of the rear of the screen, which is then passed to the controller 23.
  • the controller 23 is a small computer that determines the position of the four reflective dots 33 in the image. This analysis of the image is not difficult, since these four dots dominate the image.
  • the controller determines from the position and spacing of the dots in the image how far away the screen is and its precise direction, and adjusts the projection head for direction and divergence of the light accordingly.
  • Fig. 2 shows a schematic section through the screen 3 representing a slight variation on the screen of Fig. 1 in that the phosphors are on the far side from the projector, while it has in common that it is to be viewed from the far side of the screen.
  • the screen is based on a sheet substrate 37 of plastics material, on which the phosphor layer 31, here shown as a continuous layer, is formed. Between the substrate and the phosphors is a selectively reflecting layer 35.
  • This layer is in essence an interference filter formed of a stack of layers of refractive indices chosen to pass the activation light (UV) but to reflect all visible wavelengths.
  • the effect of the filter is almost to double the output of the display because the light from the phosphors 31 is all directed towards the viewer, whereas without the filter half of it would have been directed backwards and would have been lost in the system.
  • the above embodiment uses amplitude or intensity modulation and either full -image projection or raster scanning on to the screen. It would also be possible to use phase modulation to produce the image.
  • the liquid crystal is addressed so as to produce a diffraction pattern which has the effect of diffracting the input light in some directions and not others, giving rise to an image. Again this method can be applied with either a full-frame or a raster-scan technique .
  • Fig. 3 shows a second embodiment of the invention, illustrating the scanning technique.
  • reference may be made, for instance, to US 5646766 (Conemac/ Advanced laser Technologies Inc.), US 5311321 (Crowley/ Corporation for Laser Optics Research) or US 5424771 (Yu/ Samsung) .
  • a UV or near-UV visible laser 41 emits a light beam which is modulated by a liquid- crystal modulator 45 or, as in US 5311321, an acoustic- optic modulator. The beam is then directed at a screen 3 of similar constitution to that in the previous embodiment .
  • This architecture is analogous to the traditional CRT but has significant advantages: • Light path folding techniques can be used to make it more compact ;
  • the screen can be flat and of arbitrary size as it is not limited by the size and weight (not to mention bulk) of the glass envelope.
  • the viewing characteristics remain those of a CRT otherwise, and in contrast to prior-art laser projectors the projection optics need not be corrected for chromatic aberrations because the projected light is largely monochromatic. Moreover the fact that only one laser, rather than three, is needed is an enormous simplification.
  • the excitation laser would be UV, but the principle would still work with a visible laser
  • the "divergence" is effected by the modulator unit 45 itself, which simultaneously controls the amplitude modulation of the laser beam and its direction, so no projective optics are required.
  • the laser and the scanning and modulating device could be replaced by a CRT laser screen such as is described in Nasibov et al , "Full colour TV projector based on A 2 B 6 electron-beam pumped semiconductor lasers", Journal of Crystal Growth 117 (1992) pp. 1040-1045 or US 5339003 (Koslovsky et al) .
  • the phosphor screen of a CRT is replaced by a layer of lasing material pumped locally by the electron beam so as to emit electromagnetic radiation.
  • projection optics might be required in order to project the modulated light correctly from the CRT laser screen onto the viewing screen. Even so these optics would be considerably simpler than current projection optics since they do not need to correct for chromatic aberration, the projected light being largely monochromatic .

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  • Physics & Mathematics (AREA)
  • Nonlinear Science (AREA)
  • Optics & Photonics (AREA)
  • Engineering & Computer Science (AREA)
  • Multimedia (AREA)
  • Signal Processing (AREA)
  • Mathematical Physics (AREA)
  • Chemical & Material Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • General Physics & Mathematics (AREA)
  • Liquid Crystal (AREA)
  • Transforming Electric Information Into Light Information (AREA)

Abstract

Selon cette invention, le principe de l'affichage à cristaux liquides photoluminescent (PLLCD) est appliqué à un affichage par projection. Une source (11) de rayons U.V. en grande partie monochromes et quasi-visibles oriente le rayonnement d'excitation à travers un modulateur à cristaux liquides (ou acousto-optique) (15). Les matières photoluminescentes (31), qui émettent un rayonnement visible lorsqu'elles sont atteintes par le rayonnement d'excitation, sont fixées sur un écran (3) et le rayonnement d'excitation est projeté sur cet écran par un projecteur (17) dans le but de former une image visible. Cette image est commandée par un mécanisme de rétroaction situé sur l'écran et comportant des spots réfléchissants (33), une caméra vidéo (121) et une unité de commande (23). Selon un autre mode de réalisation, on peut utiliser une technique de balayage par faisceau laser. Vu que ce système ne nécessite qu'un rayonnement monochrome pour la projection, il peut être bien plus simple que les affichages par projection rouge-vert-bleu.
PCT/GB1998/001396 1997-05-15 1998-05-15 Systeme d'affichage WO1998052359A1 (fr)

Priority Applications (2)

Application Number Priority Date Filing Date Title
EP98921619A EP0981911A1 (fr) 1997-05-15 1998-05-15 Systeme d'affichage
AU74406/98A AU7440698A (en) 1997-05-15 1998-05-15 Display system

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GBGB9709926.1A GB9709926D0 (en) 1997-05-15 1997-05-15 Liquid-crystal display
GB9709926.1 1997-05-15

Publications (1)

Publication Number Publication Date
WO1998052359A1 true WO1998052359A1 (fr) 1998-11-19

Family

ID=10812396

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/GB1998/001396 WO1998052359A1 (fr) 1997-05-15 1998-05-15 Systeme d'affichage

Country Status (4)

Country Link
EP (1) EP0981911A1 (fr)
AU (1) AU7440698A (fr)
GB (1) GB9709926D0 (fr)
WO (1) WO1998052359A1 (fr)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2000017700A1 (fr) * 1998-09-21 2000-03-30 Screen Technology Limited Montage optique pour ecrans plats
EP1026901A1 (fr) * 1999-02-02 2000-08-09 C.R.F. Società Consortile per Azioni Dispositif d'affichage comprenant un écran photoluminescent
WO2001052555A2 (fr) * 2000-01-13 2001-07-19 Infineon Technologies Ag Systeme de projection video et procede pour projeter des donnes video a l'aide d'un laser sur une surface de projection
DE10042974A1 (de) * 2000-09-01 2002-03-28 Samsung Sdi Co Verfahren zum elektrischen Adressieren von Fluoreszenz-Anzeigeelementen und Anzeigeelement
US8240854B2 (en) 2006-12-19 2012-08-14 Koninlijke Philips Electronics N.V. Autostereoscopic display device and a system using the same
EP2708948A1 (fr) * 2011-05-10 2014-03-19 Dai Nippon Printing Co., Ltd. Dispositif d'éclairage, dispositif d'affichage d'images de type par projection et dispositif optique

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2118803A (en) * 1982-04-05 1983-11-02 British Broadcasting Corp Display device
JPH02199975A (ja) * 1989-01-27 1990-08-08 Sony Corp ディスプレイ装置
WO1990012387A1 (fr) * 1989-04-07 1990-10-18 Aubusson Russell C Appareil d'affichage d'images en mouvement a ecriture laser
WO1996041322A1 (fr) * 1995-06-07 1996-12-19 Philips Electronics N.V. Source lumineuse de type panneau plat pour dispositif d'affichage a cristaux liquides

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2118803A (en) * 1982-04-05 1983-11-02 British Broadcasting Corp Display device
JPH02199975A (ja) * 1989-01-27 1990-08-08 Sony Corp ディスプレイ装置
WO1990012387A1 (fr) * 1989-04-07 1990-10-18 Aubusson Russell C Appareil d'affichage d'images en mouvement a ecriture laser
WO1996041322A1 (fr) * 1995-06-07 1996-12-19 Philips Electronics N.V. Source lumineuse de type panneau plat pour dispositif d'affichage a cristaux liquides

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
CROSSLAND W A ET AL: "33.1: INVITED PAPER: PHOTOLUMINESCENT LCDS (PL-LCDS) USING PHOSPHORS", 13 May 1997, 1997 SID INTERNATIONAL SYMPOSIUM DIGEST OF TECHNICAL PAPERS, BOSTON, MAY 13 - 15, 1997, NR. VOL. 28, PAGE(S) 837 - 840, SOCIETY FOR INFORMATION DISPLAY, XP000722821 *
PATENT ABSTRACTS OF JAPAN vol. 014, no. 483 (E - 0993) 22 October 1990 (1990-10-22) *

Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2000017700A1 (fr) * 1998-09-21 2000-03-30 Screen Technology Limited Montage optique pour ecrans plats
EP1026901A1 (fr) * 1999-02-02 2000-08-09 C.R.F. Società Consortile per Azioni Dispositif d'affichage comprenant un écran photoluminescent
WO2001052555A2 (fr) * 2000-01-13 2001-07-19 Infineon Technologies Ag Systeme de projection video et procede pour projeter des donnes video a l'aide d'un laser sur une surface de projection
WO2001052555A3 (fr) * 2000-01-13 2001-12-06 Infineon Technologies Ag Systeme de projection video et procede pour projeter des donnes video a l'aide d'un laser sur une surface de projection
DE10042974A1 (de) * 2000-09-01 2002-03-28 Samsung Sdi Co Verfahren zum elektrischen Adressieren von Fluoreszenz-Anzeigeelementen und Anzeigeelement
DE10042974B4 (de) * 2000-09-01 2008-04-30 Samsung SDI Co., Ltd., Suwon Verfahren zum elektrischen Adressieren von Fluoreszenz-Anzeigeelementen und Anzeige
US8240854B2 (en) 2006-12-19 2012-08-14 Koninlijke Philips Electronics N.V. Autostereoscopic display device and a system using the same
EP2708948A1 (fr) * 2011-05-10 2014-03-19 Dai Nippon Printing Co., Ltd. Dispositif d'éclairage, dispositif d'affichage d'images de type par projection et dispositif optique
EP2708948A4 (fr) * 2011-05-10 2015-04-15 Dainippon Printing Co Ltd Dispositif d'éclairage, dispositif d'affichage d'images de type par projection et dispositif optique
US9609294B2 (en) 2011-05-10 2017-03-28 Dai Nippon Printing Co., Ltd. Illumination device, projection type image display device, and optical device
CN107577112A (zh) * 2011-05-10 2018-01-12 大日本印刷株式会社 照明装置、投射型影像显示装置及光学装置
EP3312670A1 (fr) * 2011-05-10 2018-04-25 Dai Nippon Printing Co., Ltd. Dispositif d'éclairage, dispositif d'affichage d'images de type à projection et dispositif optique

Also Published As

Publication number Publication date
GB9709926D0 (en) 1997-07-09
AU7440698A (en) 1998-12-08
EP0981911A1 (fr) 2000-03-01

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