Patent EP0131341A1 successfully refreshed from Google Patents.
EP0131341A1
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Method of reducing the reflectance of a transparent viewing screen and viewing screen with reduced reflectance
Assignee: Koninklijke Philips NV
•
Filing: 1984-07-10
•
Granted: —
•
Expires: 2004-07-10
Abstract
Abstract Aviewing screen is described, in particularthe screen of a display tube, which has excellent antireflective properties and a method of making this screen anti-reflective. Firstly 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 Maria Marinus Pasmans
- 👤 Pieter Van Der Werf
- 👤 Albertus Johannes Maria Rombouts
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-09 04:04
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: 13
Claim 1
Independent Claim
47 words
A method of reducing the reflectance of a transparent viewing screen, characterized in that firstly the outer surface of the screen is mechanically roughened and subsequently the roughened outer surface is provided with an anti-reflective voating in such a manner that this coating has a constant thickness.
Claim 2
Independent Claim
47 words
A method of reducing the reflectance of a transparent viewing screen, characterized in that firstly the outer surface of the screen is mechanically roughened and subsequently the roughened outer surface is provided with an anti-reflective voating in such a manner that this coating has a constant thickness.
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
26 words
A method as claimed in Claim 1 or 2, characterized in that the roughening is effected by means of loose grains on a flexible polishing base.
Claim 5
Dependent Claim
26 words
A method as claimed in Claim 1, 2 or 3, characterized in that the anti-reflective coating is formed by vapour-deposition or sputtering in a vacuum system.
Claim 6
Dependent Claim
51 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 0 to the normal to said outer surface.
Claim 7
Dependent Claim
27 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
85 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/um < S m < 100 / um the anti-reflective coating on the roughened outer surface having a constant thickness and following the surface profile after roughening.
Claim 10
Dependent Claim
85 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/um < S m < 100 / um 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
56 words
A picture screen as claimed in Claim 8 or 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 13
Dependent Claim
17 words
A television picture tube provided with a viewing screen as claimed in Claim 8, 9 or 10.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
Maintenance schedule is calculated for granted US utility patents.