US3689760A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Efficient reflector for a projector
Assignee: Mattel Inc
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Filing: 1971-01-25
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Granted: 1972-09-05
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Expires: 1991-01-25
Abstract
Abstract An efficient projector for film slides or the like, which can project a uniformly bright image on a screen using a low wattage lamp and a small diameter projection lens, comprising a reflector for reflecting light from a lamp through a frame area of the film plane and through a lens. The reflector is shaped so that most of the light rays emanating from the lamp are reflected to a small area of the lens plane to enable a small lens to be used, the rays being directed along paths that cause uniform illumination of a predetermined frame area of the film plane.
Inventors
- 👤 George W Stewart Jr
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 13:12
CPC Classifications
G; G03; G03B; G03B21/00; G03B21/14; G03B21/20
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
198 words
A projector comprising: a housing; means defining a film plane within said housing; a concentrated light source behind said film plane; a projector lens located in front of said film plane, for focusing an image of material at said film plane onto a screen; and a reflector disposed about said light source and shaped to reflect light emitted by said light source through said film plane and thence through said lens, said reflector shaped to substantially uniformly illuminate the frame area at said film plane with rays that travel in paths that lead through the area encompassed by said lens, said reflector shaped and positioned with respect to said light source so that substantially all of the light reflected by said reflector passes through said frame area, said light source and frame area defining an imaginary optical axis extending from the center of said light source to the center of said frame area, and said reflector having perimeter portions that reflect light rays so they lie on the same side of the optical axis at said reflector as at said frame area, whereby to minimize spreading of the light so that a small projector lens can be used.
Claim 2
Dependent Claim
198 words
A projector comprising: a housing; means defining a film plane within said housing; a concentrated light source behind said film plane; a projector lens located in front of said film plane, for focusing an image of material at said film plane onto a screen; and a reflector disposed about said light source and shaped to reflect light emitted by said light source through said film plane and thence through said lens, said reflector shaped to substantially uniformly illuminate the frame area at said film plane with rays that travel in paths that lead through the area encompassed by said lens, said reflector shaped and positioned with respect to said light source so that substantially all of the light reflected by said reflector passes through said frame area, said light source and frame area defining an imaginary optical axis extending from the center of said light source to the center of said frame area, and said reflector having perimeter portions that reflect light rays so they lie on the same side of the optical axis at said reflector as at said frame area, whereby to minimize spreading of the light so that a small projector lens can be used.
Claim 3
Dependent Claim
22 words
The projector described in claim 1 wherein: said reflector subtends a solid angle of more than 6 steradians about said light source.
Claim 4
Dependent Claim
154 words
In an optical system wherein light is directed from a substantially point source through a lens, an imaginary line connecting the point source and the center of the lens defining an optical axis of the system, the improvEment comprising: a concave reflector disposed about said point source and having a perimeter portion near the reflector perimeter, which is shaped to direct at least some of the light rays across said optical axis, with reflector portions thereof progressively nearer said perimeter oriented to direct light across points on said optical axis which are progressively nearer said point source; said reflector having a radially inner portion near the radially innermost location that is shaped to direct at least some of the light rays across said optical axis, with regions of said inner portion progressively nearer said radially innermost location oriented to direct light across points on said optical axis which are progressively nearer said point source.
Claim 5
Dependent Claim
154 words
In an optical system wherein light is directed from a substantially point source through a lens, an imaginary line connecting the point source and the center of the lens defining an optical axis of the system, the improvEment comprising: a concave reflector disposed about said point source and having a perimeter portion near the reflector perimeter, which is shaped to direct at least some of the light rays across said optical axis, with reflector portions thereof progressively nearer said perimeter oriented to direct light across points on said optical axis which are progressively nearer said point source; said reflector having a radially inner portion near the radially innermost location that is shaped to direct at least some of the light rays across said optical axis, with regions of said inner portion progressively nearer said radially innermost location oriented to direct light across points on said optical axis which are progressively nearer said point source.
Claim 6
Dependent Claim
116 words
In an optical system wherein light is directed from a substantially point source through a lens, an imaginary line connecting the point source and the center of the lens defining an optical axis of the system, the improvement comprising: a concave reflector disposed about said point source and having a perimeter portion near the reflector perimeter, which is shaped to direct at least some of the light rays across said optical axis, with reflector portions thereof progressively nearer said perimeter oriented to direct light across points on said optical axis which are progressively nearer said point source; said reflector being shaped to substantially uniformly illuminate a film frame area located between said point source and lens.
Claim 7
Dependent Claim
116 words
In an optical system wherein light is directed from a substantially point source through a lens, an imaginary line connecting the point source and the center of the lens defining an optical axis of the system, the improvement comprising: a concave reflector disposed about said point source and having a perimeter portion near the reflector perimeter, which is shaped to direct at least some of the light rays across said optical axis, with reflector portions thereof progressively nearer said perimeter oriented to direct light across points on said optical axis which are progressively nearer said point source; said reflector being shaped to substantially uniformly illuminate a film frame area located between said point source and lens.
Claim 8
Dependent Claim
106 words
In an optical system wherein light is directed from a substantially point source through a lens, an imaginary line connecting the point source and the center of the lens defining an optical axis of the system, the improvement comprising: a concave reflector disposed about said point source and having a perimeter portion, an inner portion, and a middle portion halfway between said perimeter and middle portions, all of said portions reflecting light through said lens, said reflector shaped so that said middle portion reflects light rays to cross said optical axis further from said light source than light rays reflected by said inner or perimeter portions.
Claim 9
Dependent Claim
106 words
In an optical system wherein light is directed from a substantially point source through a lens, an imaginary line connecting the point source and the center of the lens defining an optical axis of the system, the improvement comprising: a concave reflector disposed about said point source and having a perimeter portion, an inner portion, and a middle portion halfway between said perimeter and middle portions, all of said portions reflecting light through said lens, said reflector shaped so that said middle portion reflects light rays to cross said optical axis further from said light source than light rays reflected by said inner or perimeter portions.
Claim 10
Dependent Claim
109 words
In an optical system wherein light is directed from a substantially point source through a lens, an imaginary line connecting the point source and the center of the lens defining an optical axis of the system, the improvement comprising: a concave reflector disposed about said point source and having a radially inner region near the center of the reflector, which is shaped to direct at least some of the light rays across said optical axis, with reflector portions of said radially inner region which are progressively nearer said center of said reflector oriented to direct light across points on said optical axis which are progressively nearer said point source.
Claim 11
Dependent Claim
109 words
In an optical system wherein light is directed from a substantially point source through a lens, an imaginary line connecting the point source and the center of the lens defining an optical axis of the system, the improvement comprising: a concave reflector disposed about said point source and having a radially inner region near the center of the reflector, which is shaped to direct at least some of the light rays across said optical axis, with reflector portions of said radially inner region which are progressively nearer said center of said reflector oriented to direct light across points on said optical axis which are progressively nearer said point source.
Claim 12
Dependent Claim
60 words
The improvement described in claim 6 including: means for holding a lens in front of said point source and at a position along said optical axis in front of a location where some of said rays have crossed said optical axis and behind the positions where other of said rays would cross said optical axis if they were not interrupted.
Claim 13
Independent Claim
253 words
A method for constructing a reflector that can reflect light from a substantially point light source onto a film plane spaced from the light source, in a manner that substantially uniformly illuminates a region of said film plane about the center thereof where an imaginary optical axis extending from said light source crosses said film plane, comprising: positioning a plurality of successive reflective elements that are located progressively further from said optical axis and which are oriented so they can reflect successive rays emanating from a location representing said light source in directions that cross said film plane at points thereon that are progressively further from said center thereof; said reflective elements being located and oriented so that predetermined rays emanating from said light source lOcation and angularly spaced from one another thereabout to provide the same said angle between pairs of adjacent rays when they are revolved about said optical axis, are directed to cross said film plane at locations radially spaced from the center of said film plane, selecting the radial distance along the film plane of each ray from the said optical axis so that successive pairs of said predetermined rays are radially spaced from one another by distances inversely proportional to the radial distance of the ray from the center of the film plane; and forming a reflector which, at a cross-section which includes said optical axis, defines a reflector surface of the same curvature as an imaginary line that smoothly connects the locations of said successive reflective elements.
Claim 14
Independent Claim
253 words
A method for constructing a reflector that can reflect light from a substantially point light source onto a film plane spaced from the light source, in a manner that substantially uniformly illuminates a region of said film plane about the center thereof where an imaginary optical axis extending from said light source crosses said film plane, comprising: positioning a plurality of successive reflective elements that are located progressively further from said optical axis and which are oriented so they can reflect successive rays emanating from a location representing said light source in directions that cross said film plane at points thereon that are progressively further from said center thereof; said reflective elements being located and oriented so that predetermined rays emanating from said light source lOcation and angularly spaced from one another thereabout to provide the same said angle between pairs of adjacent rays when they are revolved about said optical axis, are directed to cross said film plane at locations radially spaced from the center of said film plane, selecting the radial distance along the film plane of each ray from the said optical axis so that successive pairs of said predetermined rays are radially spaced from one another by distances inversely proportional to the radial distance of the ray from the center of the film plane; and forming a reflector which, at a cross-section which includes said optical axis, defines a reflector surface of the same curvature as an imaginary line that smoothly connects the locations of said successive reflective elements.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-09-05 | 1976-03-06 | 1976-09-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-09-05 | 1980-03-06 | 1980-09-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-09-05 | 1984-03-06 | 1984-09-05 | $7700.00 | Window Closed / Lapsed |