US5005945A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Rear projection screen and rear projection system comprising such a screen
Assignee: US Philips Corp
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Filing: 1990-07-19
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Granted: 1991-04-09
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Expires: 2010-07-19
Abstract
Abstract In a rear projection screen having a large horizontal viewing angle caused by the shape of the first light-spreading elements (51) provided at the front side of the plate (50) the color shift is corrected by providing second light-spreading elements (61) at the rear side of the plate. The second light-spreading elements are aligned approximately parallel to the first light-spreading elements and have a pitch (p) which is considerably smaller than the pitch of the first light-spreading elements. This screen provides a good color correction while the first and the second light-spreading elements are formed in such a way that the screen can be manufactured on an industrial scale without any problem.
Inventors
- 👤 Johannes C. van de Ven
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 14:06
CPC Classifications
G; G03; G03B; G03B21/00; G03B21/54; G03B21/56; G03B21/60; G03B21/62; G03B21/625
Claims Analysis
Total Claims: 28
Claim 1
Independent Claim
137 words
A rear projection screen having a front and a rear side for displaying at the front side of the screen a picture supplied by a plurality of primary picture sources arranged at the rear side of the screen, said screen comprising a translucent plate whose front side is provided with a multitude of parallel-arranged first light-spreading elements extending in one direction across the plate for spreading light in a first plane perpendicular to the said direction, said elements having steep edges for obtaining total internal reflection and having a top with a portion for transmission and refraction, characterized in that the rear side of the plate is provided with parallel-arranged second light-spreading elements which extend mainly in the said direction, for spreading light already upon its entrance into the plate in a plane perpendicular to said direction.
Claim 2
Dependent Claim
137 words
A rear projection screen having a front and a rear side for displaying at the front side of the screen a picture supplied by a plurality of primary picture sources arranged at the rear side of the screen, said screen comprising a translucent plate whose front side is provided with a multitude of parallel-arranged first light-spreading elements extending in one direction across the plate for spreading light in a first plane perpendicular to the said direction, said elements having steep edges for obtaining total internal reflection and having a top with a portion for transmission and refraction, characterized in that the rear side of the plate is provided with parallel-arranged second light-spreading elements which extend mainly in the said direction, for spreading light already upon its entrance into the plate in a plane perpendicular to said direction.
Claim 3
Dependent Claim
30 words
A rear projection screen as claimed in claim 1, characterized in that the pitch of the second light-spreading elements is considerably smaller than the pitch of the first light-spreading elements.
Claim 4
Dependent Claim
34 words
A rear projection screen as claimed in claim 1 or 2, characterized in that the pitch of the second light-spreading elements is at most approximately 1/5 of the pitch of the first light-spreading elements.
Claim 5
Dependent Claim
39 words
A rear projection screen as claimed in claim 1 or 2 characterized in that the second light-spreading elements extend in a direction at an angle of at most 30° to the direction in which the first light-spreading elements extend.
Claim 6
Dependent Claim
40 words
A rear projection system as claimed in claim 1, characterized in that the second light-spreading elements refract light which is substantially perpendicularly incident on the rear side of the screen through an angle which is at most approximately 20° .
Claim 7
Dependent Claim
43 words
A rear projection screen as claimed in claim 1, 2, or 5, characterized in that the maximum angle between the surface of the second light-spreading elements and the plane of the plate has a value of between approximately 20° and approximately 40° .
Claim 8
Dependent Claim
20 words
A rear projection screen as claimed in claim 1, 2, characterized in that the second light-spreading elements are convex elements.
Claim 9
Dependent Claim
20 words
A rear projection screen as claimed in claim 1, 2, characterized in that the second light-spreading elements are concave elements.
Claim 10
Dependent Claim
27 words
A rear projection screen as claimed in claim 1, 2, characterized in that a plurality of the second light-spreading elements is convex and a plurality is concave.
Claim 11
Dependent Claim
23 words
A rear projection screen as claimed in claim 9, characterized in that the convex and concave second light-spreading elements alternate with one another.
Claim 12
Dependent Claim
29 words
A rear projection screen as claimed in claim 10, characterized in that the cross-sections of the second light-spreading elements approximately have the shape of a segment of a circle.
Claim 13
Dependent Claim
24 words
A rear projection screen as claimed in claim 11, characterized in that a segment of a circle forms an arc of approximately 60° .
Claim 14
Dependent Claim
19 words
A rear projection screen as claimed in claim 1 characterized in that a diffusor is arranged in the plate.
Claim 15
Dependent Claim
20 words
A rear projection screen as claimed in claim 1 characterized in that the rear side of the plate is anti-reflective.
Claim 16
Dependent Claim
36 words
A rear projection system comprising a plurality of primary pictures sources, a plurality of lens systems and a rear projection screen as claimed in claim 1 for projecting the picture generated by the primary picture source.
Claim 17
Dependent Claim
37 words
A rear projection screen as claimed in claim 3, characterized in that the second light-spreading elements extend in a direction at an angle of at most 30° to the direction in which the first light-spreading elements extend.
Claim 18
Dependent Claim
40 words
A rear projection screen as claimed in claim 3, characterized in that the maximum angle between the surface of the second light-spreading elements and the plane of the plate has a value of between approximately 20° and approximately 40° .
Claim 19
Dependent Claim
40 words
A rear projection screen as claimed in claim 4, characterized in that the maximum angle between the surface of the second light-spreading elements and the plane of the plate has a value of between approximately 20° and approximately 40° .
Claim 20
Dependent Claim
19 words
A rear projection screen as claimed in claim 3, characterized in that the second light-spreading elements are convex elements.
Claim 21
Dependent Claim
19 words
A rear projection screen as claimed in claim 4, characterized in that the second light-spreading elements are convex elements.
Claim 22
Dependent Claim
19 words
A rear projection screen as claimed in claim 6, characterized in that the second light-spreading elements are convex elements.
Claim 23
Dependent Claim
19 words
A rear projection screen as claimed in claim 3, characterized in that the second light-spreading elements are concave elements.
Claim 24
Dependent Claim
19 words
A rear projection screen as claimed in claim 4, characterized in that the second light-spreading elements are concave elements.
Claim 25
Dependent Claim
19 words
A rear projection screen as claimed in claim 6, characterized in that the second light-spreading elements are concave elements.
Claim 26
Dependent Claim
26 words
A rear projection screen as claimed in claim 3, characterized in that a plurality of the second light-spreading elements is convex and a plurality is concave.
Claim 27
Dependent Claim
26 words
A rear projection screen as claimed in claim 4, characterized in that a plurality of the second light-spreading elements is convex and a plurality is concave.
Claim 28
Dependent Claim
26 words
A rear projection screen as claimed in claim 6, characterized in that a plurality of the second light-spreading elements is convex and a plurality is concave.
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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) | 1994-04-08 | 1994-10-08 | 1995-04-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1998-04-08 | 1998-10-08 | 1999-04-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2002-04-08 | 2002-10-08 | 2003-04-09 | $7700.00 | Window Closed / Lapsed |