US3909655A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Cathode ray tube having cylinder with internal resistive helix
Assignee: EMI Group Ltd
•
Filing: 1973-07-03
•
Granted: 1975-09-30
•
Expires: 1993-07-03
Abstract
Abstract A cathode ray tube housing an electron gun assembly mounted within a sealed evacuated envelope formed substantially of electrically insulating material has a first coating of electrically conductive material on part of its external surface and a second coating of electrically conductive material on part of its internal surface. The conductive coatings forming a capacitor. To minimize the effects of flashover, this capacitor is electrically connected to an electrode of the electron gun assembly by a resistor included in the electron gun assembly.
Inventors
- 👤 Michael Charles Grimmett
- 👤 Douglas Gerald Crawley
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 11:58
CPC Classifications
H; H01; H01J; H01J29/00; H01J29/96; H01J2229/00; H01J2229/48; H01J2229/4824; H01J2229/4827
Claims Analysis
Total Claims: 2
Claim 1
Independent Claim
329 words
A cathode ray tube having an electron gun assembly mounted within a sealed evacuated envelope formed substantially of electrically insulating material and having a first coating of electrically conductive material on part of its external surface and a second coating of electrically conductive material on part of its internal surface, the coatings forming a capacitor which is electrically connected to the final anode of the electron gun assembly by a resistor included in the assembly, a small part of the envelope being formed by an electrically conductive connector, and a clearance being left between the external coating and the connector so that they are electrically insulated from one another, the connector making electrical contact with a first portion of the second coating which portion is in the form of a layer of conducting graphite, the internal coating having a second portion which is in the form of a layer of aluminium which makes electrical connection with the first portion at a common boundary lying in a plane, the said resistor having a conductive element which provides the resistance of the resistor and is supported by a rigid member formed of electrically insulating material and is in the form of a helix of resistive material, the rigid member being a hollow cylinder, the said helix being coaxial with the cylinder and disposed on the internal surface of the cylinder with a protective layer of chromic oxide overlying the conductive element, that end of the element which is nearer to the said first portion of the internal coating being electrically connected to it through a plurality of spring contacts, an outwardly directed flange of a flanged metal member, and a further plurality of spring contacts, the said contacts having their respective free ends in electrical contact with the said end of the element and the portion of the internal coating, and the other end of the element being electrically connected to the final anode through a further plurality of spring contacts.
Claim 2
Dependent Claim
329 words
A cathode ray tube having an electron gun assembly mounted within a sealed evacuated envelope formed substantially of electrically insulating material and having a first coating of electrically conductive material on part of its external surface and a second coating of electrically conductive material on part of its internal surface, the coatings forming a capacitor which is electrically connected to the final anode of the electron gun assembly by a resistor included in the assembly, a small part of the envelope being formed by an electrically conductive connector, and a clearance being left between the external coating and the connector so that they are electrically insulated from one another, the connector making electrical contact with a first portion of the second coating which portion is in the form of a layer of conducting graphite, the internal coating having a second portion which is in the form of a layer of aluminium which makes electrical connection with the first portion at a common boundary lying in a plane, the said resistor having a conductive element which provides the resistance of the resistor and is supported by a rigid member formed of electrically insulating material and is in the form of a helix of resistive material, the rigid member being a hollow cylinder, the said helix being coaxial with the cylinder and disposed on the internal surface of the cylinder with a protective layer of chromic oxide overlying the conductive element, that end of the element which is nearer to the said first portion of the internal coating being electrically connected to it through a plurality of spring contacts, an outwardly directed flange of a flanged metal member, and a further plurality of spring contacts, the said contacts having their respective free ends in electrical contact with the said end of the element and the portion of the internal coating, and the other end of the element being electrically connected to the final anode through a further plurality of spring contacts.
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) | 1978-09-29 | 1979-03-31 | 1979-09-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-09-29 | 1983-03-31 | 1983-09-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-09-29 | 1987-03-31 | 1987-09-30 | $7700.00 | Window Closed / Lapsed |