Patent EP0691552A2 successfully refreshed from Google Patents.
EP0691552A2
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Apparatus for uniformly illuminating a light valve
Assignee: 3M Innovative Properties Co
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Filing: 1995-06-16
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Granted: —
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Expires: 2015-06-16
Abstract
Abstract An optical system for providing uniform illumination of a light valve (12) which is light energy efficient and low in cost. The light source (4) is an extended source generally emitting a non-uniform spatial distribution of light power. Source light (14) is focused into the entrance end of a light transmitting tunnel (2) having reflecting interior wall surfaces and having cross sectional (N) and length dimensions (4) chosen to deliver, at the exit end of the tunnel (2), light which is substantially uniform in power distribution over the surface area of the exit end due to multiple reflections from the tunnel walls. The exiting light is advantageously used to uniformly illuminate a light valve (12). The inventive light transmitting system has the advantages of being simple in construction, efficient in utilization of source light (4), and flexible in terms of the space limitations which may be accommodated. An embodiment of the inventive illumination system includes a compound light transmitting tunnel (2) with a plurality of segments (62,74,76) and exits ends. Jointing means (64,66,68) between adjacent segments (62,74,76) divide light into a transmitted range of wavelengths and a reflected range of wavelengths.
Inventors
- 👤 Simon Magarill
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-09 14:56
CPC Classifications
G; G02; G02B; G02B27/00; G02B27/09; G02B27/0938; G02B27/0994; G02B17/00; G02B27/10; G02B27/1006; G02B27/102; G02B27/1046; G02B27/14; G02B27/145; G02B5/00; G02B5/08; G02B5/10; H; H04; H04N; H04N9/00; H04N9/12; H04N9/31; H04N9/3141; H04N9/315; G02B6/00; G02B6/24; G02B6/42; G02B6/4298; G02F; G02F1/00; G02F1/01; G02F1/13; G02F1/133; G02F1/1333; G02F1/1335; G02F1/1336; G02F1/133602; G02F1/133605
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
147 words
Apparatus for uniformly illuminating a light valve comprising: a light source; a light transmitting tunnel, said tunnel having reflective walls and a rectangular cross section of smaller inside dimension N, a length L, an entrance end and an exit end; means for focusing the light from said source into a light spot directed into said entrance end, wherein the angular aperture of said focusing means is the angle u and the largest cross sectional dimension of said light spot is D, and D is less than or equal to said smaller dimension N, and wherein L, N and u are related by the equation, L = k*N/tan(u), wherein k is a constant in the range of about 1.5 to 3; and, a light valve having an active area, said valve disposed at said exit end to receive, on said active area, light transmitted by said light tunnel.
Claim 2
Dependent Claim
22 words
Apparatus of claim 1 wherein the angular aperture of the light cone exiting said tunnel is less than or equal to u.
Claim 3
Dependent Claim
35 words
Apparatus according to claim 1 or 2, wherein said active area of said light valve is a reactangle having dimensions P and Q and wherein the ratio P/Q is essentially equal to the ratio M/N.
Claim 4
Dependent Claim
62 words
Apparatus of claim 1, 2 or 3 further comprising an optical system interposed between said exit end and said light valve, said optical system producing an image of the light at said exit end on said active area of said light valve, wherein optionally the dimensions of said image substantially correspond to the dimensions of said active area of said light valve.
Claim 5
Dependent Claim
56 words
Apparatus of claim 1, 2, 3 or 4 wherein light emerging from said exit end has an aperture u and said optical system has an input side and an output side, said input side facing said exit end and the angular aperture of said input side is greater than or equal to said angular aperture u.
Claim 6
Dependent Claim
78 words
Apparatus of claim 1 wherein said light tunnel is hollow and the interior of said walls reflect light from said light source, optionally said light tunnel being a right parallelepiped, or said light tunnel walls tapering uniformly thereby forming a cross section which changes uniformly in area along the length of said light tunnel, further optionally said tunnel walls tapering from a smaller cross section at said entrance end to a larger cross section at said exit end.
Claim 7
Dependent Claim
60 words
Apparatus of claim 1 or 6 wherein said light tunnel further comprises a solid material which fills the space defined by said tunnel walls, said material being transparent to light from said light source and wherein the refractive index of said material is such that within said solid material total internal reflection of said light from said light source occurs.
Claim 8
Dependent Claim
21 words
Apparatus of any one of claims 1-7, wherein said light valve is a liquid crystal display, or a deformable mirror device.
Claim 9
Dependent Claim
112 words
Apparatus according to any one of the preceding claims, said tunnel having a first and a second segment, each said segment having walls and a rectangular cross section, said first segment having a smaller inside dimension N, wherein the interior surface of said walls of said sections are reflective of light from said source and wherein, said segments are arranged to lie in a plane and are fixedly joined to exclude external light and optically joined by means for transmitting light from said first segment into said second segment, and the included angle between said segments is substantially 90° and wherein said spot is directed into said entrance end of first segment.
Claim 10
Dependent Claim
105 words
Apparatus of claim 9 wherein said first segment comprises a first sub-segment and a second sub-segment, said first sub-segment having an entrance end, said first sub-segment entrance end coinciding with said first segment entrance end, an exit end and a length less than the length of said first segment, said exit end of said first sub-segment fixedly joined to said second sub-segment, wherein said first sub-segment is uniformly tapered so that the cross section of said entrance end of said first sub-segment is smaller than the cross section of said exit end of said first sub-segment and said second sub-segment is of constant cross section.
Claim 11
Dependent Claim
107 words
Apparatus of claim 9 or 10 wherein said second segment comprises a first sub-segment and a second sub-segment, said first sub-segment having an entrance end, said first sub-segment entrance end coinciding with said second segment entrance end, an exit end and a length less than the length of said second segment, said exit end of said first sub-segment fixedly joined to said second sub-segment, wherein said first sub-segment is uniformly tapered so that the cross section of said entrance end of said first sub-segment is smaller than the cross section of said exit end of said first sub-segment and said second sub-segment is of constant cross section.
Claim 12
Dependent Claim
17 words
Apparatus of claim 9, 10, or 11 wherein said optical joining means is a right angle prism.
Claim 13
Independent Claim
113 words
An apparatus for uniformly illuminating a rectangular light valve comprising: a light source; a light transmitting tunnel having a rectangular cross section, light reflecting interior walls, an entrance end and an exit end, wherein the aspect ratio of said exit end substantially equals the aspect ratio of said light valve, said tunnel being sufficiently long that, when a cone of light enters said tunnel, the integration factor of the exiting light is greater than or equal to about 85% and the length of said tunnel being sufficiently short such that the power transmission through said tunnel is greater than about 85%; and means for relaying light exiting said tunnel to said light valve.
Claim 14
Independent Claim
342 words
An apparatus for uniformly illuminating a plurality of light valves comprising: a light source; a compound light transmitting tunnel comprising, a plurality of segments having interior walls reflective of light from said source, an entrance end and an exit end, each said exit and entrance end having a rectangular cross section, a plurality of joint members, each said member having one entrance end, a first and a second exit end, and filtering and directing means fixedly positioned within said joint member whereby a range of light wavelengths incident upon said entrance end of said joint member is divided into a first sub-range of wavelengths which is reflected from said filter and through said first exit end and a second sub-range of wavelengths which is transmitted through said filter and through said second exit end, a first said segment fixedly positioned to receive into said entrance end light from said source, said entrance end of a first said joint member fixedly joined to said exit end of said first segment, said entrance end of a second said segment fixedly joined to said first exit of said first joint, said entrance end of a third said segment fixedly joined to said second exit of said first joint, said entrance end of a second said joint member fixedly joined to said exit end of said second segment, said entrance end of a third said joint member fixedly joined to said exit end of said third segment, said entrance end of a fourth segment fixedly joined to said first exit of said second joint member, said entrance of a fifth segment fixedly joined to said second exit of said second joint member, and said entrance of a sixth segment fixedly joined to said first exit of said third joint member; and, fixedly positioned at said exit ends of said fourth, fifth and six segment, respectively, a light valve each said light valve having an active area, said active area substantially uniformly illuminated by light from said respective exit ends of said fourth, fifth and sixth segment.
Claim 15
Dependent Claim
71 words
Apparatus of claim 14 wherein at least one said segment is uniformly tapered, and/or said first segment is uniformly tapered such that the cross section of said entrance end is smaller than the cross section of said exit end, and/or the angular aperture of said entrance light is greater than or equal to the angular aperture of light emerging from said exit ends of said respective fourth, fifth and sixth segment.
Claim 16
Dependent Claim
187 words
A mirror assembly for collecting light from a source and directing the light onto a target comprising: a truncated ellipsoidal mirror, having an reflective concave surface, a near and a far focal point and a circular edge in the plane of the truncation; a first annular paraboloid mirror, having a focus point, a reflective concave surface and having respective circular edges of larger and a smaller circular diameter, the smaller diameter circular edge of said annular paraboloid mirror joined to the circular edge of said ellipsoidal mirror; and, a second annular paraboloid mirror, having a focus point, a reflective concave surface and a larger and a smaller diameter circular edge, the larger circular edge of said second annular paraboloid mirror joined to the larger circular edge of said first annular paraboloid mirror, so that the reflective surface of said second paraboloid mirror faces the reflective surface of said ellipsoidal mirror; wherein the near focal point of said ellipsoidal mirror and the respective focus points of said first and second annular paraboloid mirrors are essentially coincident and are essentially coincident with the geometric center of the light source.
Claim 17
Dependent Claim
85 words
The mirror assembly of claim 16 further including an annular spherical mirror, having a center of curvature and a reflective concave surface, spaced apart from, facing and symmetrically disposed about the smaller diameter circular edge of said second annular paraboloid mirror, wherein the center of curvature is coincident with the geometric center of the light source, and/or wherein the respective circular openings of said second annular paraboloid mirror and said annular spherical mirror are chosen to allow passage of light reflected from said ellipsoidal mirror.
References Cited (Backward Citations)
US3170980A
Cited
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