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1. (WO1998053608) CONTRAST IMPROVEMENT IN LIQUID CRYSTAL LIGHT VALVE PROJECTORS
Latest bibliographic data on file with the International Bureau

Pub. No.: WO/1998/053608 International Application No.: PCT/BE1998/000073
Publication Date: 26.11.1998 International Filing Date: 20.05.1998
Chapter 2 Demand Filed: 20.07.1998
IPC:
G02F 1/1335 (2006.01) ,H04N 5/74 (2006.01)
G PHYSICS
02
OPTICS
F
DEVICES OR ARRANGEMENTS, THE OPTICAL OPERATION OF WHICH IS MODIFIED BY CHANGING THE OPTICAL PROPERTIES OF THE MEDIUM OF THE DEVICES OR ARRANGEMENTS FOR THE CONTROL OF THE INTENSITY, COLOUR, PHASE, POLARISATION OR DIRECTION OF LIGHT, e.g. SWITCHING, GATING, MODULATING OR DEMODULATING; TECHNIQUES OR PROCEDURES FOR THE OPERATION THEREOF; FREQUENCY-CHANGING; NON-LINEAR OPTICS; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
1
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
01
for the control of the intensity, phase, polarisation or colour
13
based on liquid crystals, e.g. single liquid crystal display cells
133
Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
1333
Constructional arrangements
1335
Structural association of optical devices, e.g. polarisers, reflectors, with the cell
H ELECTRICITY
04
ELECTRIC COMMUNICATION TECHNIQUE
N
PICTORIAL COMMUNICATION, e.g. TELEVISION
5
Details of television systems
74
Projection arrangements for image reproduction, e.g. using eidophor
Applicants:
BARCO N.V. [BE/BE]; Frankrijklaan 18 B-8970 Poperinge, BE (AllExceptUS)
MAXIMUS, Bart [BE/BE]; BE (UsOnly)
CANDRY, Patrick [BE/BE]; BE (UsOnly)
VAN DEN BOSSCHE, Bart [BE/BE]; BE (UsOnly)
Inventors:
MAXIMUS, Bart; BE
CANDRY, Patrick; BE
VAN DEN BOSSCHE, Bart; BE
Priority Data:
97870070.620.05.1997EP
Title (EN) CONTRAST IMPROVEMENT IN LIQUID CRYSTAL LIGHT VALVE PROJECTORS
(FR) AMELIORATION DU CONTRASTE DANS DES PROJECTEURS A MODULATEUR A CRISTAUX LIQUIDES
Abstract:
(EN) The present invention relates to a light valve image projector with a disposition for improving the contrast of an optical image projected on a screen by that projector. The projector comprises at least one illumination system, at least one field lens, at least one set consisting of a polariser, an LCD and an analyser and at least a projection lens, and presents at least one optical axis which includes an angle $g(a) with the optical axis of the projection lenses. The invention consists in positioning the analyser (25) so that it includes an angle larger than $g(a) with the LCD, at least for the light rays that pass through the contrast limiting area of the LCD. The invention consists furthermore in placing the polariser so that it includes an angle larger than $g(a) with the LCD. Both the analyser and/or the polariser may have a flat or a curved surface.
(FR) L'invention concerne un projecteur d'image à modulateur de lumière, disposé de sorte que le contraste d'une image optique projetée sur un écran par ledit projecteur soit amélioré. Ledit projecteur comporte au moins un système d'éclairage, au moins une lentille de champ, au moins un ensemble constitué d'un polariseur, d'un écran à cristaux liquides et d'un analyseur, et au moins une lentille de projection, et présente au moins un axe optique qui forme un angle $g(a) avec l'axe optique des lentilles de projection. L'amélioration de l'invention consiste à positionner l'analyseur (25) de sorte qu'il forme un angle supérieur à $g(a) avec l'écran à cristaux liquides, au moins pour les rayons lumineux traversant la zone de limitation du contraste de l'écran à cristaux liquides. Elle consiste encore à placer le polariseur de sorte qu'il forme un angle supérieur à $g(a) avec l'écran à cristaux liquides. L'analyseur et/ou le polariseur peuvent présenter une surface courbe ou plate.
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Designated States: AL, AM, AT, AU, AZ, BA, BB, BG, BR, BY, CA, CH, CN, CU, CZ, DE, DK, EE, ES, FI, GB, GE, GH, GM, GW, HU, ID, IL, IS, JP, KE, KG, KP, KR, KZ, LC, LK, LR, LS, LT, LU, LV, MD, MG, MK, MN, MW, MX, NO, NZ, PL, PT, RO, RU, SD, SE, SG, SI, SK, SL, TJ, TM, TR, TT, UA, UG, US, UZ, VN, YU, ZW
African Regional Intellectual Property Organization (ARIPO) (GH, GM, KE, LS, MW, SD, SZ, UG, ZW)
Eurasian Patent Organization (AM, AZ, BY, KG, KZ, MD, RU, TJ, TM)
European Patent Office (AT, BE, CH, CY, DE, DK, ES, FI, FR, GB, GR, IE, IT, LU, MC, NL, PT, SE)
African Intellectual Property Organization (BF, BJ, CF, CG, CI, CM, GA, GN, ML, MR, NE, SN, TD, TG)
Publication Language: English (EN)
Filing Language: English (EN)
Also published as:
NO19995597EP0880279US6224215JP2001526801 CA2290686AU1998074192