Patent US3846012A successfully refreshed from Google Patents.
US3846012A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Transparent front projection screen having concave ridges thereon
Assignee: Qantix Corp
•
Filing: 1973-11-14
•
Granted: 1974-11-05
•
Expires: 1993-11-14
Abstract
Abstract A front projection screen is disclosed which is made from a transparent material. Optical elements are formed on the back side thereof so that light incident upon the screen from a preferred direction will be totally reflected by the screen while light incident upon the screen from other directions will pass therethrough. Sides of the optical elements are curved to provide dispersion in the horizontal plane while the front surface of the projection screen has segments of cylindrical columns formed thereon perpendicular to the optical elements to provide an angular spread in the vertical plane.
Inventors
- 👤 J Brown
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 19:07
CPC Classifications
G; G03; G03B; G03B21/00; G03B21/54; G03B21/56; G03B21/60; G03B21/602
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
101 words
A front projection screen made from a sheet of light transmitting material having a predetermined critical angle of internal reflection less than 45*; said sheet having a front surface and a back surface; said screen being characterized by: said back surface having formed thereon a plurality of parallel ridges; each of said ridges having curved sides terminating at a peak; said curved sides extending away from said sheet at an angle of approximately 45* immediately adjacent to said sheet; the angle between a line tangent to said sides and said sheet continuously increasing as said curved sides extend towards said peak.
Claim 2
Dependent Claim
101 words
A front projection screen made from a sheet of light transmitting material having a predetermined critical angle of internal reflection less than 45*; said sheet having a front surface and a back surface; said screen being characterized by: said back surface having formed thereon a plurality of parallel ridges; each of said ridges having curved sides terminating at a peak; said curved sides extending away from said sheet at an angle of approximately 45* immediately adjacent to said sheet; the angle between a line tangent to said sides and said sheet continuously increasing as said curved sides extend towards said peak.
Claim 3
Dependent Claim
46 words
The front projection screen as defined in claim 1 characterized further by: said front surface having formed thereon a plurality of parallel ridges each forming a section of a cylinder; said ridges on said front surface being dispositioned perpendicularly to said ridges on said back surface.
Claim 4
Dependent Claim
41 words
The front projection screen as defined in claim 1 in which said angle between a line tangent to said sides and said sheet is approximately equal to 60* minus one third said predetermined critical angle of internal reflection at said peaks.
Claim 5
Dependent Claim
46 words
The front projection screen as defined in claim 3 characterized further by: said front surface having formed thereon a plurality of parallel ridges each forming a section of a cylinder; said ridges on said front surface being dispositioned perpendicularly to said ridges on said back surface.
Claim 6
Dependent Claim
19 words
The combination as defined in claim 4 in which said front surface has a minimum of 500 ridges thereon.
Claim 7
Dependent Claim
19 words
The combination as defined in claim 5 in which said back surface has a minimum of 500 ridges thereon.
Claim 8
Dependent Claim
16 words
The combination as defined in claim 6 in which said light transmitting material is flint glass.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-11-04 | 1978-05-06 | 1978-11-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-11-04 | 1982-05-06 | 1982-11-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-11-04 | 1986-05-06 | 1986-11-05 | $7700.00 | Window Closed / Lapsed |