US4596942A
Expired / Lapsed
US
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Field emission type electron gun
Assignee: National Institute for Materials Science
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Filing: 1984-02-14
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Granted: 1986-06-24
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Expires: 2004-02-14
Abstract
Abstract A field emission type electron gun comprises a cathode, a plurality of anodes opposing in series to the cathode and a filament for heating the anodes, all being contained in a vacuum tube. The filament is placed immediately before a first anode directly opposing the cathode in a symmetrical manner so as to serve both as a gas expelling member and as an anode.
Inventors
- 👤 Chuhei Oshima
- 👤 Yoshio Ishizawa
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 20:19
CPC Classifications
H; H01; H01J; H01J37/00; H01J37/02; H01J37/04; H01J37/06; H01J37/073
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
118 words
A field emission type electron gun comprising: a cathode, a plurality of anodes opposite, in series, to said cathode; and a filament for heating said anodes, wherein said cathode, said plurality of anodes and said filament are all contained in a vacuum tube, wherein said filament is placed proximal to a first anode having a first voltage and being directly opposite said cathode in a symmetrical manner so as to serve both as a gas expelling member and as an anode and wherein a power source is connected between said filament and said first anode in order to apply to said filament a voltage substantially equal to or slightly lower than said first voltage of said first anode.
Claim 2
Dependent Claim
118 words
A field emission type electron gun comprising: a cathode, a plurality of anodes opposite, in series, to said cathode; and a filament for heating said anodes, wherein said cathode, said plurality of anodes and said filament are all contained in a vacuum tube, wherein said filament is placed proximal to a first anode having a first voltage and being directly opposite said cathode in a symmetrical manner so as to serve both as a gas expelling member and as an anode and wherein a power source is connected between said filament and said first anode in order to apply to said filament a voltage substantially equal to or slightly lower than said first voltage of said first anode.
Claim 3
Dependent Claim
17 words
A field emission type electron gun according to claim 1, wherein said anode is a horn-shaped plate.
Claim 4
Dependent Claim
35 words
A field emission type electron gun according to claim 1, wherein said filament is provided in a plane substantially perpendicular to the central axis of an electron beam emitted from said cathode to said anodes.
Claim 5
Dependent Claim
23 words
A field emission type electron gun according to claim 1, wherein said filament is formed in a shape of vortex or coaxial circles.
Claim 6
Dependent Claim
40 words
A field emission type electron gun according to claim 2, wherein the slope of said horn-shaped plate is steepest at the reduced diameter end, gradually decreases toward the flared skirt portion and is substantially zero at the enlarged diameter end.
Claim 7
Dependent Claim
25 words
A field emission type electron gun according to claim 2, wherein the reduced diameter end of said first anode is substantially flush with said filament.
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) | 1989-06-23 | 1989-12-23 | 1990-06-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1993-06-23 | 1993-12-23 | 1994-06-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1997-06-23 | 1997-12-23 | 1998-06-24 | $7700.00 | Window Closed / Lapsed |