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Patent US4831307A successfully refreshed from Google Patents.
US4831307A
Expired / Lapsed
US
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Cathode ray tube with light reflection film
Assignee: Toshiba Corp
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Filing: 1987-12-23
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Granted: 1989-05-16
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Expires: 2007-12-23
Abstract
Abstract In a cathode ray tube, a single layer for prevention of a reflection of light rays is formed on a face plate having a non-spherical outer surface. The thickness of the layer is continuously decreased from the center region toward the peripheral regions of the face plate.
Inventors
- 👤 Shigeo Takenaka
- 👤 Takeo Itou
- 👤 Hidemi Matsuda
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 13:49
CPC Classifications
H; H01; H01J; H01J29/00; H01J29/86; H01J29/88; H01J29/89; H01J29/896; H01J2229/00; H01J2229/89; H01J2229/8913; H01J2229/8918
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
132 words
A cathode ray tube having a face plate having a non-spherical curved surface in which a picture image is displayed, comprising: a layer for the prevention of the reflection of light rays, said layer being formed on the surface of the face plate, the thickness of said layer continuously decreasing from the center region toward the peripheral regions of said face plate, at a rate of change (d/max) given as: (X/Xmax).sup.2 =(d/dmax -1){η·d/dmax-(kη-1/k-1)} where X is a distance from the center point of the faceplate, d is the thickness of the layer, dmax is the maximum value of the layer thickness, k is the value of d/max for X=Xmax, and η is a constant concerning the rate of change in the thickness of the layer and satisfies the inequality (1/(k-1) 2 >η).
Claim 2
Dependent Claim
132 words
A cathode ray tube having a face plate having a non-spherical curved surface in which a picture image is displayed, comprising: a layer for the prevention of the reflection of light rays, said layer being formed on the surface of the face plate, the thickness of said layer continuously decreasing from the center region toward the peripheral regions of said face plate, at a rate of change (d/max) given as: (X/Xmax).sup.2 =(d/dmax -1){η·d/dmax-(kη-1/k-1)} where X is a distance from the center point of the faceplate, d is the thickness of the layer, dmax is the maximum value of the layer thickness, k is the value of d/max for X=Xmax, and η is a constant concerning the rate of change in the thickness of the layer and satisfies the inequality (1/(k-1) 2 >η).
Claim 3
Dependent Claim
42 words
The cathode ray tube according to claim 1, wherein said layer is made of a material having a refractive index (n) lower than the refractive index of said face plate, and the thickness of said layer ranges from 0.22/n to 0.04/n μm.
Claim 4
Dependent Claim
21 words
The cathode ray tube according to claim 1, wherein said non-spherical curved surface is defined by a compound radius of curvature.
Claim 5
Dependent Claim
16 words
The cathode ray tube according to claim 1, wherein said layer is made of magnesium fluoride.
Claim 6
Dependent Claim
15 words
The cathode ray tube according to claim 1, wherein said layer is a single-layered structure.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1992-05-15 | 1992-11-14 | 1993-05-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-05-15 | 1996-11-14 | 1997-05-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-05-15 | 2000-11-14 | 2001-05-16 | $7700.00 | Window Closed / Lapsed |