US4914510A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method for improving the white field uniformity of a projection color TV using CRTs having interference filters, projection color TV and CRTs resulting from the method
Assignee: Philips North America LLC
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Filing: 1988-12-23
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Granted: 1990-04-03
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Expires: 2008-12-23
Abstract
Abstract The white field uniformity of a projection color TV employing three monochrome cathode ray tubes is improved by matching the center-to-edge luminance gradient of the red-emitting and/or blue-emitting tube to that of the green-emitting tube having an interference filter. In a preferred embodiment, such matching is achieved by applying an optical filter of varying density on the outside surface of the display window of the tube.
Inventors
- 👤 Matthew S. Brennesholtz
- 👤 Raymond G. Greene
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 17:34
CPC Classifications
H; H04; H04N; H04N9/00; H04N9/12; H04N9/31; H01; H01J; H01J29/00; H01J29/86; H01J29/89; H01J29/894
Claims Analysis
Total Claims: 32
Claim 1
Independent Claim
66 words
A method for improving the white field uniformity of a projection color television display device incorporating red, blue and green monochrome cathode ray tubes, at least one tube having an interference filter, the method comprising altering the center-to-edge luminance gradient of at least one of the tubes to match the center-to-edge luminance gradient of the tube to that of at least one of the other tubes.
Claim 2
Independent Claim
66 words
A method for improving the white field uniformity of a projection color television display device incorporating red, blue and green monochrome cathode ray tubes, at least one tube having an interference filter, the method comprising altering the center-to-edge luminance gradient of at least one of the tubes to match the center-to-edge luminance gradient of the tube to that of at least one of the other tubes.
Claim 3
Dependent Claim
14 words
The method of claim 1 in which the green tube has an interference filter.
Claim 4
Dependent Claim
24 words
The method of claim 1 in which center-to-edge gradient of the red tube is altered to match the center-to-edge gradient of the green tube.
Claim 5
Dependent Claim
28 words
The method of claim 3 in which the center-to-edge gradient of the blue tube is altered to match the matched center-to-edge gradients of the red and green tubes.
Claim 6
Dependent Claim
55 words
The method of claim 2 in which the red tube has an interference filter and in which the filter is formed at a thickness to result in a center-to-edge gradient smaller than that of the green tube, and the center-to-edge gradient of the red tube is then increased to match that of the green tube.
Claim 7
Dependent Claim
46 words
The method of claim 5 in which the center-to-edge gradient of the red tube is increased by applying a variable transmission optical filter to the outside surface of the display window, the transmission of which filter decreases from the center to the edge of the window.
Claim 8
Dependent Claim
13 words
The method of claim 6 in which the filter comprises a half-tone pattern.
Claim 9
Dependent Claim
17 words
The method of claim 6 in which the filter comprises a continuous layer of variable optical density.
Claim 10
Dependent Claim
121 words
A three-tube color projection television display device having red, blue and green emitting monochrome cathode ray display tubes, the tubes each 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 at least one of the tubes also comprising an interference filter between the luminescent material layer and the display window, characterized in that means are included for altering the center-to-edge luminance gradient of at least one of the tubes in order to match the luminance gradient of the tube to that of at least one of the other tubes, and thereby improve white field uniformity of the display.
Claim 11
Dependent Claim
121 words
A three-tube color projection television display device having red, blue and green emitting monochrome cathode ray display tubes, the tubes each 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 at least one of the tubes also comprising an interference filter between the luminescent material layer and the display window, characterized in that means are included for altering the center-to-edge luminance gradient of at least one of the tubes in order to match the luminance gradient of the tube to that of at least one of the other tubes, and thereby improve white field uniformity of the display.
Claim 12
Dependent Claim
18 words
The projection television display device of claim 9 in which the green emitting tube comprises an interference filter.
Claim 13
Dependent Claim
20 words
The projection television display device of claim 9 in which gradient altering means are included for the red emitting tube.
Claim 14
Dependent Claim
22 words
The projection television display device of claim 11 in which the gradient altering means are also included for the blue emitting tube.
Claim 15
Dependent Claim
16 words
The projection television display device of claim 9 in which the means comprises an optical filter.
Claim 16
Dependent Claim
16 words
The projection television display device of claim 13 in which the filter is inside the tube.
Claim 17
Dependent Claim
22 words
The projection television display device of claim 13 in which the filter is located on the outside surface of the display window.
Claim 18
Dependent Claim
27 words
The projection television display device of claim 13 in which the filter is located in the optical projection system adjacent the outside surface of the display window.
Claim 19
Dependent Claim
16 words
The projection television display device of claim 9 in which the means comprises the projection lens.
Claim 20
Dependent Claim
18 words
The projection television display device of claim 9 in which the means comprises tube drive signal modulating means.
Claim 21
Dependent Claim
19 words
The projection television display device of claim 9 in which the means comprises electron attenuation means inside the tube.
Claim 22
Dependent Claim
60 words
A monochrome cathode ray tube for projection television 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, characterized in that means are included for altering the center-to-edge luminance gradient of the tube comprising a single layer optical filter.
Claim 23
Dependent Claim
60 words
A monochrome cathode ray tube for projection television 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, characterized in that means are included for altering the center-to-edge luminance gradient of the tube comprising a single layer optical filter.
Claim 24
Dependent Claim
15 words
The tube of claim 20 in which the filter is comprised of a half-tone pattern.
Claim 25
Dependent Claim
19 words
The tube of claim 21 in which the pattern is comprised of an array of spaced-apart substantially opaque dots.
Claim 26
Dependent Claim
18 words
The tube of claim 20 in which the filter is located on the outside of the display window.
Claim 27
Dependent Claim
15 words
The tube of claim 20 in which the transmission of the filter decreases from center-to-edge.
Claim 28
Dependent Claim
8 words
The tube of claim 20 which is red-emitting.
Claim 29
Dependent Claim
8 words
The tube of claim 20 which is blue-emitting.
Claim 30
Dependent Claim
17 words
The tube of claim 20 in which the filter comprises a continuous coating of varying optical density.
Claim 31
Dependent Claim
63 words
A monochrome cathode ray tube fort projection television 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, characterized in that means are included for altering the center-to-edge luminance gradient of the tube comprising a layer of an electron beam attenuating material.
Claim 32
Dependent Claim
63 words
A monochrome cathode ray tube fort projection television 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, characterized in that means are included for altering the center-to-edge luminance gradient of the tube comprising a layer of an electron beam attenuating material.
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) | 1993-04-02 | 1993-10-02 | 1994-04-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-04-02 | 1997-10-02 | 1998-04-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-04-02 | 2001-10-02 | 2002-04-03 | $7700.00 | Window Closed / Lapsed |