US4731558A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of reducing the reflectance of a transparent viewing screen and viewing screen with reduced reflectance
Assignee: US Philips Corp
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Filing: 1986-11-03
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Granted: 1988-03-15
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Expires: 2006-11-03
Abstract
Abstract A viewing screen is described, in particular the screen of a display tube, which has excellent anti-reflective properties and a method of making this screen anti-reflective. In this method the outer surface of the screen is mechanically roughened in conformity with specific requirements and subsequently an anti-reflective coating of constant thickness is applied to the roughened surface.
Inventors
- 👤 Jan Haisma
- 👤 Johannes M. M. Pasmans
- 👤 Pieter van der Werf
- 👤 Albertus J. M. Rombouts
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 03:23
CPC Classifications
H; H04; H04N; H04N5/00; H04N5/64; H04N5/65; G; G02; G02B; G02B1/00; G02B1/10; G02B1/11; G02B1/113; H01; H01J; H01J29/00; H01J29/02; H01J29/10; H01J29/18; H01J29/24; H01J29/86; H01J29/89; H01J29/896; H01J2229/00; H01J2229/89; H01J2229/8913; H01J2229/8915; H01J2229/8918
Claims Analysis
Total Claims: 19
Claim 1
Independent Claim
168 words
A method of reducing the reflectance of a transparent viewing screen comprising first mechanically roughening the outer surface of the screen until the roughness parameters of the resultant roughened outer surface satisfies the following requirements 25 nm<R a <200 nm 50 nm<R q <250 nm 25 nm<R tm <1500 nm 25 μm<S m <100 μm wherein R a is the arithmetic average of the absolute difference between the surface profile and the average surface level measured along a line, R q is the square root of the average difference squared between the surface profile and the average surface level measured along a line, R tm is the peak-to-valley height difference of the surface profile averaged over a number of line intervals, and S m is the average distance between positive crossings of the surface profile and the average surface level measured along a line and then providing an anti-reflective coating on the roughened outer surface in such a manner that the thickness of the resultant coating is constant.
Claim 2
Independent Claim
168 words
A method of reducing the reflectance of a transparent viewing screen comprising first mechanically roughening the outer surface of the screen until the roughness parameters of the resultant roughened outer surface satisfies the following requirements 25 nm<R a <200 nm 50 nm<R q <250 nm 25 nm<R tm <1500 nm 25 μm<S m <100 μm wherein R a is the arithmetic average of the absolute difference between the surface profile and the average surface level measured along a line, R q is the square root of the average difference squared between the surface profile and the average surface level measured along a line, R tm is the peak-to-valley height difference of the surface profile averaged over a number of line intervals, and S m is the average distance between positive crossings of the surface profile and the average surface level measured along a line and then providing an anti-reflective coating on the roughened outer surface in such a manner that the thickness of the resultant coating is constant.
Claim 3
Dependent Claim
21 words
A method as claimed in claim 1, characterized in that the inner surface of the viewing screen is also roughened mechanically.
Claim 4
Dependent Claim
24 words
A method as claimed in claim 2, characterized in that the roughening is effected by means of loose grains on a flexible polishing base.
Claim 5
Dependent Claim
23 words
A method as claimed in claim 3, characterized in that the anti-reflective coating is formed by vapour-deposition or sputtering in a vacuum system.
Claim 6
Dependent Claim
49 words
A method as claimed in claim 4, characterized in that on the roughened outer surface of the screen a layer of magnesium-fluoride is vapour-deposited as anti-reflective coating, the vapour-deposition flow towards said outer surface being directed at an angle smaller than 15° to the normal to said outer surface.
Claim 7
Dependent Claim
28 words
A method as claimed in claim 5, characterized in that during vapour-deposition the outer surface of the viewing screen is brought at a temperature of approximately 300° C.
Claim 8
Dependent Claim
44 words
A method as claimed in claim 5, characterized in that prior to vapour-deposition the outer surface of the screen is chemically activated by subjecting it to a glow-discharge for at least 15 minutes and during vapour-deposition this outer surface is maintained at room temperature.
Claim 9
Dependent Claim
162 words
A viewing screen whose outer surface is provided with an anti-reflective coating, characterized in that at least the outer surface of the viewing screen is mechanically roughened, the roughness parameters satisfying the following requirements: 25 nm>R a >200 nm 50 nm<R q <250 nm 250 nm<R tm <1500 nm 25 μm<S m <100 μm wherein R a is the arithmetic average of the absolute difference between the surface profile and the average surface level measured along a line, R q is the square root of the average difference squared between the surface profile and the average surface level measured along a line, R tm is the peak-to-valley height difference of the surface profile averaged over a number of line intervals, and S m is the average distance between positive crossings of the surface profile and the average surface level measured along a line the anti-reflective coating on the roughened outer surface having a constant thickness and following the surface profile after roughening.
Claim 10
Dependent Claim
162 words
A viewing screen whose outer surface is provided with an anti-reflective coating, characterized in that at least the outer surface of the viewing screen is mechanically roughened, the roughness parameters satisfying the following requirements: 25 nm>R a >200 nm 50 nm<R q <250 nm 250 nm<R tm <1500 nm 25 μm<S m <100 μm wherein R a is the arithmetic average of the absolute difference between the surface profile and the average surface level measured along a line, R q is the square root of the average difference squared between the surface profile and the average surface level measured along a line, R tm is the peak-to-valley height difference of the surface profile averaged over a number of line intervals, and S m is the average distance between positive crossings of the surface profile and the average surface level measured along a line the anti-reflective coating on the roughened outer surface having a constant thickness and following the surface profile after roughening.
Claim 11
Dependent Claim
21 words
A viewing screen as claimed in claim 8, characterized in that the inner surface of the screen is also mechanically roughened.
Claim 12
Dependent Claim
54 words
A picture screen as claimed in claim 8, characterized in that the anti-reflective coating comprises a single layer whose refractive index is smaller than that of the viewing-screen material and whose optical thickness is equal to a quarter of a reference wavelength for the range of wavelengths for which the reflectance must be reduced.
Claim 13
Dependent Claim
14 words
A television picture tube provided with a viewing screen as claimed in claim 8.
Claim 14
Dependent Claim
24 words
A method as claimed in claim 2, characterized in that the roughening is effected by means of loose grains on a flexible polishing base.
Claim 15
Dependent Claim
23 words
A method as claimed in claim 2, characterized in that the anti-reflective coating is formed by vapour-deposition or sputtering in a vacuum system.
Claim 16
Dependent Claim
24 words
A method as claimed in claim 4, characterized in that the roughening is effected by means of loose grains on a flexible polishing base.
Claim 17
Dependent Claim
54 words
A picture screen as claimed in claim 9, characterized in that the anti-reflective coating comprises a single layer whose refractive index is smaller than that of the viewing-screen material and whose optical thickness is equal to a quarter of a reference wavelength for the range of wavelengths for which the reflectance must be reduced.
Claim 18
Dependent Claim
14 words
A television picture tube provided with a viewing screen as claimed in claim 9.
Claim 19
Dependent Claim
14 words
A television picture tube provided with a viewing screen as claimed in claim 10.
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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) | 1991-03-15 | 1991-09-14 | 1992-03-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-03-15 | 1995-09-14 | 1996-03-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-03-15 | 1999-09-14 | 2000-03-15 | $7700.00 | Window Closed / Lapsed |