EP0154053A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Projection screen
Assignee: Koninklijke Philips NV
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Filing: 1984-12-18
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Granted: —
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Expires: 2004-12-18
Abstract
Abstract A blackened optical system transmission sheet (11) includes a transparent substrate (16) having a front side (12) provided with at least a pair of elongate ribs (22) forming therebetween an elongate groove (28). An amount of optically black discrete particles (30) for absorbing visible ambient light is disposed in the groove. The particle amount is contained within the groove by means of a skin (34) which extends between the ribs and over the groove.
Inventors
- 👤 Douglas Allan Stanton
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-26 00:23
CPC Classifications
G; G03; G03B; G03B21/00; G03B21/54; G03B21/56; G03B21/60; G03B21/62; G03B21/625
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
61 words
An optical transmission sheet, comprising a substrate having a planar front surface; and a plurality of elongate mutually parallel ribs provided on the front surface, the ribs being successively laterally adjacent, each rib being laterally spaced from a successively adjacent rib to form a respective groove therebetween, characterized in that in each groove an amount of light-absorbent discrete particles is disposed.
Claim 2
Dependent Claim
61 words
An optical transmission sheet, comprising a substrate having a planar front surface; and a plurality of elongate mutually parallel ribs provided on the front surface, the ribs being successively laterally adjacent, each rib being laterally spaced from a successively adjacent rib to form a respective groove therebetween, characterized in that in each groove an amount of light-absorbent discrete particles is disposed.
Claim 3
Dependent Claim
82 words
An optical transmission sheet, as claimed in Claim 1, characterized in that the ribs are formed of a transparent medium having a first refractive index, and the surrounding medium has a second refractive index, the first and the second refractive indexes determining a critical angle 6 c for a total internal reflection of a light ray transmitted through the rear surface and incident upon the interface between a rib and the surrounding medium, an amount of light-absorbent discrete particles are disposed loosely.
Claim 4
Dependent Claim
35 words
An optical transmission sheet as claimed in Claim 1 or 2, characterized by means for containing the particles within the grooves, the containing means including a skin extending between the ribs and over the groove.
Claim 5
Dependent Claim
20 words
An optical transmission sheet as claimed in Claim 1 or 2, characterized in that each particle comprises a fusible material.
Claim 6
Dependent Claim
24 words
An optical transmission sheet as claimed in Claim 3, characterized in that the skin consists essentially of a fused portion of the disposed particles.
Claim 7
Dependent Claim
28 words
An optical transmission sheet as claimed in any of the Claims 1-5, characterized in that the particles have a number average particle size of approximately 10 microns diameter.
Claim 8
Dependent Claim
29 words
An optical transmission sheet as claimed in Claim 3 or 5, characterized in that the skin has an average thickness in a range between approximately 40 and 90 microns.
Claim 9
Independent Claim
69 words
A method of blackening an optical transmission sheet with a substantially planar substrate having a plurality of elongate mutually parallel ribs provided on a surface of the substrate, the ribs being successively laterally adjacent, each rib being laterally spaced from a successively adjacent rib to form a respective groove therebetween, characterized by disposing an amount of light-absorbent discrete particles in each groove, and containing the particles within respective grooves.
Claim 10
Independent Claim
69 words
A method of blackening an optical transmission sheet with a substantially planar substrate having a plurality of elongate mutually parallel ribs provided on a surface of the substrate, the ribs being successively laterally adjacent, each rib being laterally spaced from a successively adjacent rib to form a respective groove therebetween, characterized by disposing an amount of light-absorbent discrete particles in each groove, and containing the particles within respective grooves.
Claim 11
Dependent Claim
32 words
A method as claimed in Claim 8, characterized in that the containing step includes fusing a portion of the particles disposed in each groove to form a skin extending between respective ribs.
Claim 12
Dependent Claim
17 words
A rear projection screen comprising an optical transmission sheet as claimed in any of the Claims 1-7.
References Cited (Backward Citations)
No citation records indexed.
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