US4683398A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Projection television display tube and device having interference filter
Assignee: US Philips Corp
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Filing: 1985-11-04
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Granted: 1987-07-28
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Expires: 2005-11-04
Abstract
Abstract A projection television display tube comprising in an evacuated envelope a display screen on the convexly curved inside of a display window in the wall of the envelope, which display screen comprises a layer of luminescent material and a multilayer interference filter between said material layer and the display window, the filter comprising a number of layers which are alternately high refractive index (H) and low refractive index (L). The filter is composed of at least 6 layers, each having an optical thickness nd, wherein n is the refractive index of the material of the layer and d is the thickness, which optical thickness is between 0.2λ f and 0.3λ f , wherein λ f is equal to p x λ, wherein λ is the desired central wavelength which is selected from the spectrum emitted by the luminescent material and p is a number between 1.18 and 1.32.
Inventors
- 👤 Leendert Vriens
- 👤 John A. Clark
- 👤 Johannes H. M. Spruit
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 15:06
CPC Classifications
H; H04; H04N; H04N5/00; H04N5/74; G; G02; G02B; G02B5/00; G02B5/20; G02B5/28; G02B5/285; H01; H01J; H01J29/00; H01J29/02; H01J29/10; H01J29/18; H01J29/185
Claims Analysis
Total Claims: 18
Claim 1
Independent Claim
215 words
A projection television display tube comprising in an evacuated envelope a display screen on the inside of a display window in the wall of the envelope, said display screen comprising a layer of a luminescent material and a multilayer interference filter between said luminescent material layer and the display window, the filter comprising a number of layers alternately having a high refractive index and a low refractive index, characterized in that the inside of the display window is substantially convex having an angle of curvature φ, wherein φ is the angle between the axis normal to the center of the display screen and a line normal to the part of the display screen farthest remote from the center, and wherein φ is between 5° and 25°, and further characterized in that the filter is composed of at least 6 layers each having an optical thickness nd, wherein n is the refractive index of the material of the layer, and d is the thickness of the layer, said optical thickness being between 0.2 λ f and 0.3 λ f , wherein λ f is equal to p x λ, where λ is the desired central wavelength which is selected from the spectrum transmitted by the luminescent material and p is a number between 1.18 and 1.32.
Claim 2
Dependent Claim
215 words
A projection television display tube comprising in an evacuated envelope a display screen on the inside of a display window in the wall of the envelope, said display screen comprising a layer of a luminescent material and a multilayer interference filter between said luminescent material layer and the display window, the filter comprising a number of layers alternately having a high refractive index and a low refractive index, characterized in that the inside of the display window is substantially convex having an angle of curvature φ, wherein φ is the angle between the axis normal to the center of the display screen and a line normal to the part of the display screen farthest remote from the center, and wherein φ is between 5° and 25°, and further characterized in that the filter is composed of at least 6 layers each having an optical thickness nd, wherein n is the refractive index of the material of the layer, and d is the thickness of the layer, said optical thickness being between 0.2 λ f and 0.3 λ f , wherein λ f is equal to p x λ, where λ is the desired central wavelength which is selected from the spectrum transmitted by the luminescent material and p is a number between 1.18 and 1.32.
Claim 3
Dependent Claim
34 words
A display tube as claimed in claim 1, characterized in that the convex inside of the display window is substantially spherical and has a radius of curvature φ between 150 nm and 730 nm.
Claim 4
Dependent Claim
23 words
A display tube as claimed in claim 1 or 2, characterized in that the filter is composed substantially of 14 to 30 layers.
Claim 5
Dependent Claim
27 words
A display tube as claimed in claim 1 or 2, characterized in that the optical thickness nd is between 0.23 λ f and 0.27 λ f .
Claim 6
Dependent Claim
59 words
A display tube as claimed in claim 1 or 2, characterized in that the layers of the filter having a high refractive index consist of titanium oxide (TiO 2 ) or tantalum oxide (Ta 2 O 5 ) and the layers having a low refractive index consist of silicon oxide (SiO 2 ) or magnesium fluoride (MgF 2 ).
Claim 7
Dependent Claim
20 words
A display tube as claimed in claim 5, characterized in that the magnesium fluoride is provided at approximately 300° C.
Claim 8
Dependent Claim
39 words
A display tube as claimed in claim 5, characterized in that the luminescent material comprises a terbium-activated substantially green-luminescing phosphor and λ=545 nm and p is a number between 1.21 and 1.25 for a TiO 2 --SiO 2 filter.
Claim 9
Dependent Claim
37 words
A display tube as claimed in claim 5, characterized in that the luminescent material comprises terbium-activated blue-luminescing phosphor and λ=490 nm and p is a number between 1.21 and 1.25 for a TiO 2 --SiO 2 filter.
Claim 10
Dependent Claim
42 words
A display tube as claimed in claim 5, characterized in that the luminescent material is europium-activated yttrium oxyde (Y 2 O 3 :Eu) and λ=612 nm and p is a number between 1.21 and 1.25 for a TiO 2 --SiO 2 filter.
Claim 11
Dependent Claim
39 words
A display tube as claimed in claim 5, characterized in that the luminescent material is zinc sulphide - silver (ZnS:Ag) and λ=460 nm and p is a number between 1.24 and 1.32 for a TiO 2 --SiO 2 filter.
Claim 12
Dependent Claim
41 words
A display tube as claimed in claim 5, characterized in that the luminescent material comprises a terbium-activated substantially green-luminescing phosphor and λ=545 nm and p is a number between 1.18 and 1.22 for a Ta 2 O 5 --SiO 2 filter.
Claim 13
Dependent Claim
40 words
A display tube as claimed in claim 5, characterized in that the luminescent material comprises a terbium-activated blue-luminescing phosphor and λ=490 nm and p is a number between 1.18 and 1.22 for a Ta 2 O 5 --SiO 2 filter.
Claim 14
Dependent Claim
44 words
A display tube as claimed in claim 5, characterized in that the luminescent material is europium-activated yttrium oxide (Y 2 O 3 :Eu) and λ=613 nm and p is a number between 1.18 and 1.22 for a Ta 2 O 5 --SiO 2 filter.
Claim 15
Dependent Claim
39 words
A display tube as claimed in claim 5, characterized in that the luminescent material is zinc sulphide-silver (ZnS:Ag) and λ=460 nm and p is a number between 1.21 and 1.28 for a Ta 2 O 5 --SiO 2 filter.
Claim 16
Dependent Claim
67 words
A display tube as claimed in claim 1, characterized in that the outermost layer of the filter which faces the luminscent material consists of a material having a high refractive index and an optical thickness of about 0.25 λ f , and is covered with a terminating layer of a material having a lower refractive index and having an optical thickness of approximately 0.125 λ f .
Claim 17
Dependent Claim
62 words
A display tube as claimed in claim 1, characterized in that the outermost layer of a filter facing the display window consists of a material having a high refractive index and an optical thickness of about 0.25 λ f , and is covered with an intermediate layer having a lower refractive index and an optical thickness of approximately 0.125 λ f .
Claim 18
Dependent Claim
73 words
A display tube as claimed in claim 5, characterized in that the outermost approximately 0.25 λ f thick layer of the filter facing the luminescent material is composed of a mixture of metal oxides, which mixture comprises titanium oxide (TiO 2 ) and a metal oxide from the group consisting of beryllium oxide (BeO), magnesium oxide (MgO) and calcium oxide (CaO), in which mixture the quantity of titanium oxide is 70-99% by weight.
References Cited (Backward Citations)
US4365183A
Cited
EP0018666A1
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1990-07-27 | 1991-01-26 | 1991-07-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-07-27 | 1995-01-26 | 1995-07-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-07-27 | 1999-01-26 | 1999-07-28 | $7700.00 | Window Closed / Lapsed |