Image projection display screen employing polymer dispersed liqu

Optical: systems and elements – Holographic system or element – Using a hologram as an optical element

Patent

Rate now

  [ 0.00 ] – not rated yet Voters 0   Comments 0

Details

359452, 359449, 359443, 359265, 359267, G02F 113, G02F 115, G03B 2160

Patent

active

054166179

DESCRIPTION:

BRIEF SUMMARY
The invention relates to a diffusing display screen, and more particularly an image projection display screen which can be used in particular in the field of high-definition television.
In fact, in this field, it is currently sought to obtain images whose dimensions are of the order of one square meter, it being possible to satisfy such a constraint by resorting to projection devices comprising cathode ray tubes or liquid crystal matrices in which the observer and the images are on the same side of the display screen.
FIG. 1 illustrates one embodiment of this type of image projector, in which the display screen constitutes an element which independent of the projector, which makes it possible to display an image whose size may be variable. It is composed of a collimated light source, of reflecting mirrors M.sub.R and of dichroic mirrors Md capable of reflecting selectively red, green and blue, as well as lenses (L) coupled with liquid crystal matrices (CL) making it possible to modulate the red, green or blue light intensities. The colour light beams are recombined, then sent to a projection objective (OP) capable of projecting the image thus constituted onto a display screen, the observer being situated between the projector and the display screen, and receiving the images reflected from the display screen. Since the display screen is not integrated with the projector, it is therefore necessary for the user to be equipped with a projector and with an independent display screen. However, the use of a display screen requires either that it be stored and be brought out solely when it is to be used, or that sufficient free space be made available to keep his display screen permanently in operating mode. In order to overcome this problem, the invention provides a device which allows the use of any transparent or non-transparent surface (window or wall) as the diffusing display screen.
For this purpose, a display screen according to the invention is placed on the surface of non-specific nature, which screen is capable of being transparent outside operating mode (allowing light to pass in the case of a window, or the wall decoration, in the case of a wall), and becoming reflecting (an advantage over conventional diffusing display screens) and diffusing like conventional display screens, in operating mode. When this type of display screen according to the invention is fixed to a window, it can advantageously be used as a shutter making it possible to isolate a subject from the outside without thereby creating a darkened zone, since the background light can be backscattered from the window which has become diffusing. The invention thus provides a diffusing display screen characterised in that it is obtained from the combination: which are dispersed microballs laid out parallel to the plane of the film, these microballs containing oblong and birefringent liquid crystal molecules of extraordinary index n.sub.e such that n.sub.e is equal to n.sub.p ; (E.sub.c), both the cells (C.sub.1) and (C.sub.2) being fixed onto a surface (S).
As shown by FIGS. 2a (transparent state) and FIGS. 2b (diffusing state), it is possible with this type of material to obtain the two desired states. In fact, it is possible to manufacture polymer films in which are dispersed balls of liquid crystal. FIG. 2a illustrates a film of polymer with dispersed liquid crystal (PDLC) at rest. The balls dispersed in the polymer may contain particles of liquid crystal, a nematic is preferably chosen which has oblong particles which are oriented parallel to a privileged axis (diagrammatically represented in FIG. 2a by the direction x). The ellipsoid of the indices of such molecules does not have symmetry of revolution, and two optical indices are conventionally defined, the ordinary optical index n.sub.o in a direction perpendicular to the long axis of the molecule, and the extraordinary index n.sub.e in a parallel direction. The manufacture of the films conventionally generates microballs laid-out parallel to the plane of the film, in which the nematic

REFERENCES:
patent: 4671617 (1987-06-01), Hara
patent: 5009044 (1991-04-01), Baughman et al.
patent: 5175637 (1992-12-01), Jones et al.
patent: 5193015 (1993-03-01), Shanks
patent: 5301046 (1994-04-01), Konuma et al.

LandOfFree

Say what you really think

Search LandOfFree.com for the USA inventors and patents. Rate them and share your experience with other people.

Rating

Image projection display screen employing polymer dispersed liqu does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Image projection display screen employing polymer dispersed liqu, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Image projection display screen employing polymer dispersed liqu will most certainly appreciate the feedback.

Rate now

     

Profile ID: LFUS-PAI-O-642185

  Search
All data on this website is collected from public sources. Our data reflects the most accurate information available at the time of publication.