Patent US4216352A successfully refreshed from Google Patents.
Patent US4773731A successfully refreshed from Google Patents.
US4773731A
Expired / Lapsed
US
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One-piece projection screen
Assignee: Philips North America LLC
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Filing: 1987-08-28
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Granted: 1988-09-27
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Expires: 2007-08-28
Abstract
Abstract A one-piece projection screen with improved overall efficiency and contrast, the elimination of corner illumination deficiencies and undesirable image artifacts. The optical power of the screen is divided between two or more surfaces acting as Fresnel lenses, and the region or medium separating the surfaces has a different index of refraction than that of the mediums upstream or downstream of the surfaces. The preferred embodiment of the projection screen includes a diffuser and a lenticular array downstream of the surfaces.
Inventors
- 👤 Jill F. Goldenberg
- 👤 Ralph H. Bradley, Jr.
- 👤 William F. Guerinot
- 👤 Thomas S. McKechnie
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 19:01
CPC Classifications
H; H04; H04N; H04N5/00; H04N5/72; G; G03; G03B; G03B21/00; G03B21/54; G03B21/56; G03B21/60; G03B21/62; G03B21/625
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
77 words
A projection screen comprising a field lens comprising at least two refractive surfaces separated by a non-adhesive region for focusing light received at said field lens from an image source via an incident medium, and a screen base coupled to said field lens, one of said refractive surfaces being a boundary of said screen base, wherein the region separating said refractive surfaces has a refractive index different from that of said incident medium and said screen base.
Claim 2
Dependent Claim
77 words
A projection screen comprising a field lens comprising at least two refractive surfaces separated by a non-adhesive region for focusing light received at said field lens from an image source via an incident medium, and a screen base coupled to said field lens, one of said refractive surfaces being a boundary of said screen base, wherein the region separating said refractive surfaces has a refractive index different from that of said incident medium and said screen base.
Claim 3
Dependent Claim
14 words
The projection screen of claim 1 wherein said refractive surfaces have common outer edges.
Claim 4
Dependent Claim
78 words
A projection screen comprising a field lens comprising at least two Fresnel lens refractive surfaces having common outer edges for focusing light received at said field lens from an image source via an incident medium, and a screen base coupled to said field lens, one of said refractive surfaces being a boundary of said screen base, wherein the region separating said refractive surfaces has a refractive index different from that of said incident medium and said screen base.
Claim 5
Dependent Claim
78 words
A projection screen comprising a field lens comprising at least two Fresnel lens refractive surfaces having common outer edges for focusing light received at said field lens from an image source via an incident medium, and a screen base coupled to said field lens, one of said refractive surfaces being a boundary of said screen base, wherein the region separating said refractive surfaces has a refractive index different from that of said incident medium and said screen base.
Claim 6
Dependent Claim
40 words
The projection screen of claim 3 wherein said screen base comprises a diffuser for controlling the vertical spread of the focused light, and a lenticular array coupled to said diffuser for wide-angle distribution of the light received from said diffuser.
Claim 7
Dependent Claim
14 words
The projection screen of claim 4 wherein the number of refractive surfaces is 2.
Claim 8
Dependent Claim
21 words
The projection screen of claim 5 wherein the optical power of said field lens is divided equally between said refractive surfaces.
Claim 9
Dependent Claim
14 words
The projection screen of claim 3 wherein the number of refractive surfaces is 2.
Claim 10
Dependent Claim
21 words
The projection screen of claim 3 wherein the optical power of said field lens is divided equally between said refractive surfaces.
Claim 11
Dependent Claim
21 words
The projection screen of claim 7 wherein the optical power of said field lens is divided equally between said refractive surfaces.
References Cited (Backward Citations)
US4053208A
Cited
US4679900A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1991-09-27 | 1992-03-28 | 1992-09-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-09-27 | 1996-03-28 | 1996-09-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-09-27 | 2000-03-28 | 2000-09-27 | $7700.00 | Window Closed / Lapsed |