Apparatus for uniformly illuminating a light valve
First Claim
1. An 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,
space="preserve" listing-type="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.
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Accused Products
Abstract
The present invention relates to an optical system for providing uniform illumination of a light valve. The light source is an extended source generally emitting a non-uniform spatial distribution of light power. Source light is focused into the entrance end of a light transmitting tunnel having reflecting interior wall surfaces and having cross sectional and length dimensions chosen to deliver, at the exit end of the tunnel, light which is substantially uniform in power distribution over the surface area of the exit end. This is caused by multiple reflections from the tunnel walls. The exiting light is advantageously used to illuminate uniformly a light valve. The tunnel may be tapered to alter the exit angular aperture. The tunnel may be hollow or filled with a transparent material. In addition, the tunnel may be segmented and folded to provide a joint which conforms tunnel geometry to given spatial limitations between source and valve. The joint also provides a convenient way of directing heat out of the tunnel structure. One embodiment of the present invention includes a compound light transmitting tunnel with a plurality of segments and exit ends. A joint between adjacent segments divides light into a transmitted range of wavelengths and a reflected range of wavelengths.
171 Citations
25 Claims
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1. An apparatus for uniformly illuminating a light valve comprising:
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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,
space="preserve" listing-type="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. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. An apparatus for uniformly illuminating a light valve comprising:
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a light source; a light transmitting tunnel, said tunnel having walls, the interior surface of said walls reflective of light from said source, a rectangular cross section having inside dimensions M and N, wherein N is the smaller inside dimension, a length L, an entrance end and an exit end; means for focusing the light from said light source into a spot and directing said spot into said entrance end, wherein the angular aperture of said focusing means is the angle u, 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,
space="preserve" listing-type="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 fixedly disposed at said exit end to receive, on said active area, light transmitted by said light tunnel wherein said active area of said light valve is a rectangle having dimensions P and Q and wherein the ratio P/Q is essentially equal to the ratio M/N. - View Dependent Claims (14, 15)
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16. An apparatus for uniformly illuminating a light valve comprising:
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a light source; a light transmitting tunnel, 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°
;means for focusing the light of said source into a spot and directing said spot into said entrance end of said first segment wherein the angular aperture of said focusing means is the angle u, 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 the angular aperture of light emerging at said exit end of said second segment is less than or equal to said angle u; and an optical system for imaging light from said exit end onto said light valve. - View Dependent Claims (17, 18, 19, 20)
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21. An apparatus for uniformly illuminating a rectangular light valve comprising:
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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.
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22. An apparatus for uniformly illuminating a plurality of light valves comprising:
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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. - View Dependent Claims (23, 24, 25)
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Specification