EP0676902A2
Expired / Lapsed
EP
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A high efficiency light valve projection system
Assignee: Projectavision Inc
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Filing: 1995-03-22
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Granted: —
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Expires: 2015-03-22
Abstract
Abstract A light valve (110,111,112) such as an active matrix LCD between crossed polarizers, utilizing, for instance individual transistors to control each "pixel area" of the LCD and storage elements to store video signal data for each pixel, with optically shielded "dead spaces" between pixels to eliminate electric field cross-talk and non-information-bearing light bleed-through, is illuminated with a bright independent light source (100,101,102) which creates a video image projected via specialized projection optics (140) onto an internal or external screen (150) without distortions, regardless of the angle of projection onto the screen. Use of heat sinks, IR reflective coatings, heat absorbing optics, optional fluid and a thermistor controlled pixel transistor bias voltage injection servo circuit stabilizes image performance maintaining accurate color and contrast levels as the LCD changes temperature. In one embodiment of the invention, use of a multi-color LCD with a stepped cavity, producing different thicknesses of LCD for the different wavelengths that pass through it, allows a linear correspondence between the wavelengths passing through the LCD to produce true black, high contrast and CRT-like color rendition. A dichroic mirror arrangement is used to overlap differently colored pixels in the projected image. Use of striped mirrors duplicate pixels, where necessary, eliminating spaces between pixels, creating a continuous image with no apparent stripes or dots. A special venetian-blind type of screen is also disclosed and methods for using the system to view three-dimensional video are also explained.
Inventors
- 👤 Eugene Dolgoff
- 👤 Paul B. Christie
- 👤 Malcolm J. Macfarlane
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-29 22:46
CPC Classifications
H; H04; H04N; H04N9/00; H04N9/12; H04N9/31; H04N9/3141; H04N9/315; H04N9/3152; H04N13/00; H04N13/30; H04N13/302; H04N13/305; H04N13/332; H04N13/337; H04N13/363; H04N13/10; H04N13/189; H04N13/194; H04N13/20; H04N13/204; H04N13/239; H04N13/261; H04N13/286; H04N13/31; H04N13/324
Claims Analysis
Total Claims: 47
Claim 1
Independent Claim
62 words
A display system, comprising: a light source; an element, wherein an image may be formed thereon; and a light tunnel located between said light source and said element for sending light from said light source to said element and having inner light-reflecting surfaces, wherein said light tunnel has an output aperture having an aspect ratio matching an aspect ratio of said element.
Claim 2
Dependent Claim
18 words
The display system of claim 1, wherein said light tunnel has one of rectangular, square and circular profiles.
Claim 3
Dependent Claim
28 words
The display system of claim 1, wherein said light tunnel has an input aperture, an output aperture and a shape which changes between said input and output apertures.
Claim 4
Dependent Claim
19 words
The display system of claim 3, wherein said light tunnel expands or contracts between said input and output apertures.
Claim 5
Dependent Claim
21 words
The display system of claim 1, wherein said light tunnel is "folded" and defines at least two light tunnel light paths.
Claim 6
Dependent Claim
15 words
The display system of claim 5, wherein said light tunnel light paths are not co-linear.
Claim 7
Dependent Claim
29 words
The display system of claim 5, further comprising at least one optical element selected from a group including a lens, mirror and prism placed between said light tunnel paths.
Claim 8
Dependent Claim
19 words
The display system of claim 1, comprising at least one lens placed between said light tunnel and said element.
Claim 9
Dependent Claim
27 words
The display system of claim 8, wherein said at least one lens focuses an image of said output aperture onto at least a portion of said element.
Claim 10
Dependent Claim
18 words
The display system of claim 1, comprising a plurality of light tunnels for sending light to said element.
Claim 11
Dependent Claim
21 words
The display system of claim 10, wherein said light tunnels have means for sending light to said element at different angles.
Claim 12
Dependent Claim
30 words
The display system of claim 1, wherein said light tunnel has flat sides in one plane and is curved in another plane such that it operates as a non-imaging concentrator.
Claim 13
Dependent Claim
29 words
The display system of claim 12, wherein said light tunnel expands as it gets closer to said element for decreasing divergence and increasing collimation of light exiting the concentrator.
Claim 14
Dependent Claim
34 words
The display system of claim 1, wherein said light tunnel has an input aperture, said display system further comprising a spherical reflector for forming an image of said light source at said input aperture.
Claim 15
Dependent Claim
102 words
A display system, comprising: a light source; an element, wherein an image may be formed thereon; at least one input lens array located between said light source and said element; and means for increasing collimation of light illuminating said element, wherein said increasing means, includes: means for increasing a diameter of a light beam such that the beam diameter is larger than said element; and means for folding light which would miss said element into said element at proper angles so that said folded light passes through elements of said at least one input lens array and pixel holes of said element.
Claim 16
Dependent Claim
40 words
The display system of claim 15, comprising means for expanding the light to a sufficient diameter so that its degree of divergence and collimation is close to an acceptance angle of elements of said at least one input lens array.
Claim 17
Dependent Claim
43 words
The display system of claim 16, wherein the folded light illuminates said element at an angle such that each element of said input lens array focuses light into a pixel other than a pixel directly in line with said input lens array element.
Claim 18
Dependent Claim
75 words
A display system, comprising: an element wherein an image may be formed thereon, wherein said element comprises at least two different areas, each displaying data corresponding to differently colored information; at least one lens array; a light source; and macro-prism means for breaking up light emanating from said light source into differently colored beams, said macro-prism means comprising at least one prism structure which is much larger than a pitch of pixels on said element.
Claim 19
Dependent Claim
14 words
The display system of claim 18, wherein said macro-prism means comprises a Fresnel prism.
Claim 20
Dependent Claim
46 words
The display system of claim 18, comprising at least two cascaded macro-prism means such that green spectrally separated beams are substantially parallel to an optical axis of a lens array element and pixel, wherein the differently colored beams illuminate pixels which display data of corresponding colors.
Claim 21
Dependent Claim
47 words
The display system of claim 20, wherein said element contains pixels which have a given horizontal pitch and wherein each lens array element of said at least one lens array has a horizontal pitch which is three times the horizontal pitch of the pixels on said element.
Claim 22
Dependent Claim
24 words
The display system of claim 20, wherein at least one of the macro-prism means makes each colored beam substantially parallel to a green beam.
Claim 23
Dependent Claim
31 words
The display system of claim 21, wherein said macro-prism means directs beams of different colors towards said element at different angles with respect to each other before hitting said lens array.
Claim 24
Dependent Claim
44 words
The display system of claim 18, further comprising an additional lens array between said element and said at least one lens array, each lens element of said additional lens array focuses light from approximately one-third of the color spectrum into a given pixel hole.
Claim 25
Dependent Claim
39 words
The display system of claim 18, wherein the spread of a color spectra is determined such that selected spectral components do not pass through any pixel holes, providing beams which pass through the pixel holes or specified color make-up.
Claim 26
Dependent Claim
71 words
A Fresnel polarizer, comprising: a multiplicity of MacNeille-type polarizers, each of which is smaller than an entire beam being polarized, and which are mounted in a fixed relationship to one another; and means for selectively altering the plane of polarization of portions of an output beam. a cholesteric-nematic liquid crystal for splitting incoming light into oppositely handed, circularly polarized beams; and quarter-wave material for turning said beams into linearly polarized beams.
Claim 27
Dependent Claim
23 words
The Fresnel polarizer of claim 26, comprising a half-wave material placed in portions of an output beam having one selected plane of polarization.
Claim 28
Dependent Claim
24 words
The Fresnel polarizer of claim 26, comprising at least two separate surfaces, each coated with a cholesteric-neumatic liquid crystal peaked at a different wavelength.
Claim 29
Dependent Claim
32 words
The Fresnel polarizer of claim 26, further comprising at least one lenticular lens array and at least one additional reflector for providing an output beam which is parallel to the input beam.
Claim 30
Dependent Claim
14 words
The Fresnel polarizer of claim 29, wherein said additional reflector comprises a Fresnel mirror.
Claim 31
Dependent Claim
72 words
The Fresnel polarizer of claim 26, comprising: at least one lenticular lens array; two elements, each having a flat side and a saw-tooth side, said two saw toothed sides being proximate to each other and having an appropriate dielectric coating between the saw-tooth sides thereof; an input side; a reflective surface opposite every other saw-tooth face on said input side; and quarter-wave material between each reflective surface and a respective saw-tooth face.
Claim 32
Dependent Claim
62 words
The Fresnel polarizer of claim 31, wherein saw-teeth on each element are 45/90 triangles with the hypotenuse of each saw-tooth of one element being parallel to the flat side of said one element, and wherein the triangular saw-teeth on the other element form a negative of the saw-teeth on said one element, whereby said two elements fit together along saw-tooth edges thereof.
Claim 33
Dependent Claim
95 words
A display system, comprising: a light source; an element, wherein an image may be formed thereon; at least one input lens array located between the element and the light source near the element; and at least one output lens array on the side of the element which is opposite the side on which the at least one input lens array is located, wherein a light source image is focused by each at least one input lens array through said element into areas beyond the element and near the at least one output lens array elements.
Claim 34
Dependent Claim
24 words
The display system of claim 33, further comprising another input lens array located between the at least one input lens array and the element.
Claim 35
Dependent Claim
24 words
The display system of claim 34, further comprising another output lens array located beyond the element and the at least one output lens array.
Claim 36
Dependent Claim
105 words
A display system, comprising: a light source; an element, wherein an image may be formed thereon; and a double lens array system located between the element and the light source near the element, wherein light from the light source is directed to pixels of the element by the double lens array system, wherein elements of the first input lens array of said double input lens array system form primary images of said light source, and elements of a second lens array of said double input lens array system focus the primary images into pixel holes of said element wherein an image may be formed thereon.
Claim 37
Dependent Claim
32 words
The display system of claim 36, wherein each element of said second lens array directs light to more than one pixel hole of said element wherein an image may be formed thereon.
Claim 38
Dependent Claim
31 words
The display system of claim 36, wherein light emanating from any one of the primary images of said light source illuminates more than one element in said second input lens array.
Claim 39
Dependent Claim
28 words
The display system of claim 36, wherein the elements of said first and second input lens arrays have approximately the same size as pixel holes in said element.
Claim 40
Dependent Claim
26 words
The display system of claim 39, wherein the elements of said first input lens array are larger than the elements of said second input lens array.
Claim 41
Dependent Claim
86 words
The display system of claim 36, wherein each of said primary images of said light source is not of the same size as a pixel hole in said element wherein an image may be formed thereon, wherein each element of said second input lens array focuses an image of said primary image which is one of positively and negatively magnified into a pixel hole, said secondary image being of the same size as the pixel hole of said elements wherein an image may be formed thereon.
Claim 42
Dependent Claim
37 words
The display system of claim 36, wherein elements of a second input lens array of said double input lens array system focus images of elements of said first input lens array into pixel holes of said element.
Claim 43
Dependent Claim
62 words
A display system comprising: a light source; an element wherein an image may be formed thereon, said element having a predetermined shape; and means for enhancing brightness of an image by shaping a beam illuminating said image-forming element such that the shape of the beam substantially matches the shape of said image-forming element, wherein said enhancing means includes a Fresnel polarizer means.
Claim 44
Dependent Claim
33 words
The display system of claim 43, wherein said enhancing means comprises means for splitting the illuminating light into differently colored beams directed to pixels on said image-forming element displaying information of corresponding colors.
Claim 45
Dependent Claim
35 words
The display system of claim 44, wherein said enhancing means includes means for increasing light collimation sufficiently to approximate an acceptance angle of input lens array elements located between said light source and said element.
Claim 46
Dependent Claim
20 words
A rear-illumination polarized screen having an enhanced ambient light rejection capability, comprising: a rear-illumination screen; and at least one polarizer.
Claim 47
Dependent Claim
123 words
An optical imaging system, comprising: a light source; a light collection means; said light collection means, including an elliptical mirror with the light source placed at a first focus of the elliptical mirror; a focusing lens which gathers light emanating from a second focus of the elliptical mirror and brings it to a third focus; a second elliptical surface to capture light that missed the first elliptical surface, said second elliptical surface curved to bring light that hits it coming from the first focus of the first ellipse to the place in space where the focusing lens comes to a focus; a collimating lens, beyond the third focus to collimate all light emanating from the focusing lens and from the second elliptical surface.
References Cited (Backward Citations)
No citation records indexed.
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