Optics: image projectors – Housing
Patent
1993-05-27
1994-09-20
Cuchlinski, Jr., William A.
Optics: image projectors
Housing
353 77, 359836, G03B 2128
Patent
active
053494008
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a back-projection display system and especially a system applicable to television. It also relates to a method for making a back-projection mirror, especially a holographic mirror.
Manufacturers of television-picture display systems tend to broaden their ranges of apparatuses and to offer customers the greatest possible choice. As regards the size of the picture, attempts are made to offer also all possible sizes and especially large-sized pictures, for example of the order of 1 meter wide.
Large-sized screens are inconceivable using the technique of conventional cathode ray tubes. Large-sized flat screens, either based on liquid crystals or based on cathode ray tubes, are not yet viable on an industrial scale.
Currently there exists, as a technique which is conceivable on an industrial-scale, only the technique employing projection onto a screen and the back-projection technique.
The direct-projection technique requires a low lighting level in the room in which the projection is performed.
The back projection technique can take up a lot of room on account of the size of the screen.
SUMMARY OF THE INVENTION
The invention relates to a back-projection system making it possible to solve the problem of taking up a lot of room.
The invention therefore relates to a back-projection display system comprising a display screen and a picture projector displaying pictures on the rear face of the screen, characterized in that the screen is attached to a fixed plane and in that it includes means enabling it to be moved away from this fixed plane or to be folded away against this fixed plane.
BRIEF DESCRIPTION OF THE DRAWINGS
The various objects and characteristics of the invention will appear more clearly in the description which follows and in the figures wherein:
FIGS. 1 and 2 show a simplified illustrative embodiment of the device of the invention;
FIGS. 3 and 4 show another simplified illustrative embodiment of the device of the invention;
FIGS. 5a and 5b, show means for protecting the mirror;
FIG. 6 shows a detailed illustrative embodiment of the device of the invention;
FIGS. 7 and 8 show a device for automatically controlling the manoeuvring of the screen according to the invention;
FIGS. 9 and 10 show examples of integrated projector/screen mountings;
FIGS. 11 and 12 show a projection system enabling two picture formats to be obtained;
FIGS. 13, 14 show a variant of the system of FIGS. 11 and 12;
FIG. 15 shows a system for articulating the mirror;
FIG. 16 shows a projection system using a holographic mirror;
FIG. 17 shows an example of a method for recording the hologram of the holographic mirror; and
FIG. 18 shows a partial view of a grid of serrations incorporated into a screen.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Before describing the illustrative embodiments with reference to the figures, it should be pointed out that these illustrative embodiments may contain characteristics which are specific to them but which are not necessarily essential within the scope of the invention.
According to the system of the invention, shown in FIGS. 1 and 2, the screen 1 is attached to the wall 4 and includes a system enabling it to be folded away against the wall. The projection apparatus 2 is attached to the ceiling 7 above the screen and the projection beam is directed vertically towards a mirror 3 located at approximately 45.degree. between the screen and the wall.
When the system is not being used, the screen 1, together with the back-projection mirror 3 is laid up against the wall 4 (FIG. 1).
During display, the screen is moved away from the wall while remaining parallel to the wall so that the back-projection mirror 3 assumes an inclined position enabling the projection beam coming from the projector 2 (FIG. 2) to be reflected onto the rear face of the screen.
The invention therefore provides articulation devices enabling the screen to be moved parallel to the wall and the inclined mirror (for example inclined at 45.degree.) to be placed beneath the projector 2.
These art
REFERENCES:
patent: 3457006 (1969-07-01), Brown
patent: 3551044 (1970-12-01), Menell
patent: 4556283 (1985-12-01), Numata et al.
patent: 4639106 (1987-01-01), Gradin
patent: 4647166 (1987-03-01), Franken et al.
patent: 5160951 (1992-11-01), Lander
IBM Technical Disclosure Bulletin, vol. 12, No. 11, Apr. 1, 1970, New York, US, pp. 1946-1947; `holographic mirrors and filters`.
Kaplan Daniel
Lehureau Jean-Claude
"Thomson-CSF"
Cuchlinski Jr. William A.
Dowling William C.
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