Patent US4950940A successfully refreshed from Google Patents.
US4950940A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Cathode ray tube with means for preventing backscatter from electron multiplier
Assignee: US Philips Corp
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Filing: 1986-12-01
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Granted: 1990-08-21
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Expires: 2006-12-01
Abstract
Abstract In order to reduce contrast degradation in an electrostatically scanned flat cathode ray tube having a channel plate electron multiplier, due to back-scattered electrons entering channels remote from their origin, a coating of a material having a low back-scatter coefficient is applied over the input of the electron multiplier between the apertures therein. The surface texture of the material should be microscopically rough. The material can be applied to the first dynode or to an electrode electrically and physically connected to the first dynode. The acceptance angle of the channel plate electron multiplier may also be restricted.
Inventors
- 👤 Alfred W. Woodhead
- 👤 Ronald W. A. Gill
- 👤 Alan G. Knapp
- 👤 Daphne L. Lamport
- 👤 Derek Washington
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 18:27
CPC Classifications
H; H01; H01J; H01J29/00; H01J29/46; H01J29/80; H01J31/00; H01J31/08; H01J31/10; H01J31/12; H01J31/123; H01J31/124; H01J43/00; H01J43/04; H01J43/06; H01J43/18; H01J43/22
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
107 words
A cathode ray tube comprising an envelope having an optically transparent faceplate and, within the envelope, means for producing an electron beam, a channel plate electron multiplier including an input side having a multiplicity of openings defining entrances to respective channels having walls including secondary emissive material, said multiplier being mounted adjacent to, but spaced from, the faceplate, scanning means for scanning the electron beam across the input side of the electron multiplier, and a layer having a low back-scatter coefficient covering the area of the input side of the electron multiplier between the openings, said back-scatter coefficient being lower than that of a smooth carbon layer.
Claim 2
Dependent Claim
107 words
A cathode ray tube comprising an envelope having an optically transparent faceplate and, within the envelope, means for producing an electron beam, a channel plate electron multiplier including an input side having a multiplicity of openings defining entrances to respective channels having walls including secondary emissive material, said multiplier being mounted adjacent to, but spaced from, the faceplate, scanning means for scanning the electron beam across the input side of the electron multiplier, and a layer having a low back-scatter coefficient covering the area of the input side of the electron multiplier between the openings, said back-scatter coefficient being lower than that of a smooth carbon layer.
Claim 3
Dependent Claim
109 words
A cathode ray tube comprising an envelope having an optically-transparent faceplate, said envelope containing: (a) means for producing an electron beam directed toward said faceplate; (b) a channel plate electron multiplier spaced from the faceplate and including an input side having a multiplicity of openings defining entrances to respective electron-multiplying channels having walls including secondary emissive material, said multiplier including a microscopically-rough layer of a material having a low back-scatter coefficient covering the area of the input side lying between the openings, said back-scatter coefficient being smaller than that of a smooth carbon layer; and (c) means for scanning the electron beam across the input side of the multiplier.
Claim 4
Dependent Claim
109 words
A cathode ray tube comprising an envelope having an optically-transparent faceplate, said envelope containing: (a) means for producing an electron beam directed toward said faceplate; (b) a channel plate electron multiplier spaced from the faceplate and including an input side having a multiplicity of openings defining entrances to respective electron-multiplying channels having walls including secondary emissive material, said multiplier including a microscopically-rough layer of a material having a low back-scatter coefficient covering the area of the input side lying between the openings, said back-scatter coefficient being smaller than that of a smooth carbon layer; and (c) means for scanning the electron beam across the input side of the multiplier.
Claim 5
Dependent Claim
114 words
A cathode ray tube comprising an envelope having an optically-transparent faceplate, said envelope containing: (a) means for producing an electron beam directed toward said faceplate; (b) a channel plate electron multiplier spaced from the faceplate and including an input side having a multiplicity of openings defining entrances to respective electron-multiplying channels, inner walls of the entrances and of the channels including secondary emissive material, said multiplier including a layer of a material having a low back-scatter coefficient covering the area of the input side lying between the openings, said back-scatter coefficient being smaller than that of a smooth carbon layer; (c) means for scanning the electron beam across the input side of the multiplier.
Claim 6
Dependent Claim
114 words
A cathode ray tube comprising an envelope having an optically-transparent faceplate, said envelope containing: (a) means for producing an electron beam directed toward said faceplate; (b) a channel plate electron multiplier spaced from the faceplate and including an input side having a multiplicity of openings defining entrances to respective electron-multiplying channels, inner walls of the entrances and of the channels including secondary emissive material, said multiplier including a layer of a material having a low back-scatter coefficient covering the area of the input side lying between the openings, said back-scatter coefficient being smaller than that of a smooth carbon layer; (c) means for scanning the electron beam across the input side of the multiplier.
Claim 7
Dependent Claim
40 words
A cathode ray tube as in claim 1, 2 or 3 where said layer has a secondary emission coefficient which is smaller than 2.0 for incident electrons having an energy lying in the range between 300 and 500 electron volts.
Claim 8
Dependent Claim
67 words
A cathode ray tube as in claim 1, 2 or 3 where said scanning means comprises a carrier member spaced from and arranged substantially parallel to said input side, the carrier member having thereon a plurality of adjacent, substantially parallel electrodes which, in response to voltages applied thereto, deflect the electron beam from a path between the carrier member and the electron multiplier toward said input side.
Claim 9
Dependent Claim
22 words
A cathode ray tube as in claim 1, 2 or 3 where said electron multiplier comprises a laminated stack of discrete dynodes.
Claim 10
Dependent Claim
19 words
A cathode ray tube as in claim 1, 2 or 3 where said layer consists essentially of black chromium.
Claim 11
Dependent Claim
19 words
A cathode ray tube as in claim 1, 2 or 3 where said layer consists essentially of black nickel.
Claim 12
Dependent Claim
19 words
A cathode ray tube as in claim 1, 2 or 3 where said layer consists essentially of black copper.
Claim 13
Dependent Claim
21 words
A cathode ray tube as in claim 1, 2 or 3 where an electrically conductive coating is applied to said layer.
Claim 14
Dependent Claim
27 words
A cathode ray tube as in claim 1, 2 or 3 where said layer consists essentially of anodized aluminum onto which an electrically conductive coating is applied.
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) | 1993-08-20 | 1994-02-19 | 1994-08-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-08-20 | 1998-02-19 | 1998-08-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-08-20 | 2002-02-19 | 2002-08-21 | $7700.00 | Window Closed / Lapsed |