Low reflectance display device

• US 4,798,994 A
• Filed: 09/04/1987
• Issued: 01/17/1989
• Est. Priority Date: 09/05/1986
• Status: Expired due to Fees

• Current Assignee: US Philips Corporation (Koninklijke Philips N.V.)
• Original Assignee: US Philips Corporation (Koninklijke Philips N.V.)
• Inventors: Rijpers, Johannes C. N., De Vrieze, Henricus M.
• Primary Examiner(s): DeMeo, Palmer C.
• Application Number:
  US07/093,450
• Time in Patent Office: 501 Days
• Field of Search: 313/478, 313/474, 313/477, 313/112, 313/480, 350/116, 350/164, 350/166
• US Class Current: 313/478
• CPC Class Codes: C03C 17/3417 all coatings being oxide coatings
• CPC Class Codes: G02B 1/115 Multilayers
• CPC Class Codes: G02B 5/285 comprising deposited thin solid films G02B5/281 - G02B5/289 take precedence; multilayered film filters for fibre optic multiplexing G02B6/29361
• CPC Class Codes: H01J 2229/8918 by using interference effects
• CPC Class Codes: H01J 29/896 Anti-reflection means, e.g. eliminating glare due to ambient light

Abstract

An anti-reflection coating which comprises at least a three layer interference filter is evaporated on the external surface of a faceplate panel. The manufacture of the coating can be speeded-up substantially by selecting high and low refractive index materials which can be evaporated at ambient temperatures and subsequently hardened by high temperature annealing outside the evaporation apparatus. The annealing is carried out most conveniently during the standard processing of a cathode ray tube.

Claims

1. A display device having an optically transparent faceplate, an anti-reflection coating on an external surface of the faceplate, the anti-reflection coating comprising at least three layers of materials which are depositable at ambient temperature by evaporation and hardenable by subsequent annealing, said layers having been hardened by annealing, the material of one of said layers having a high refractive index with respect to that of the material of the faceplate and another one of said layers having a low refractive index with respect to that of the material of the faceplate.

2. A display device as claimed in claim 1, characterized in that the high refractive index material is Nb₂ O₅.

3. A display device as claimed in claim 1, characterized in that the low refractive index material is SiO₂.

4. A display device as claimed in claim 1, characterized in that the outer surface of the faceplate is mechanically roughened.

5. A display device as claimed in claim 1, characterized in that the coating consists of four layers of which the first and second layers have a thickness of the order of λ

/8, the third layer has a thickness of the order of λ

/2, and the outermost layer has a thickness of the order of λ

/4, where λ

is equal to a desired central wavelength.

6. A display device as claimed in claim 1, characterized in that the faceplate comprises the faceplate panel of a cathode ray tube and the material of the faceplate comprises a mixed alkali glass substantially free of lead oxide (PbO).