Patent US3890533A successfully refreshed from Google Patents.
US3890533A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Thermal emission type electron gun
Assignee: Jeol Ltd
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Filing: 1973-07-09
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Granted: 1975-06-17
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Expires: 1993-07-09
Abstract
Abstract A thermal emisssion type electron gun of improved design embodying an improved Wehnelt electrode and an improved filament arrangement with respect to the Wehnelt electrode thereby ensuring the generation of an electron beam having a high degree of parallelism, high density and uniformity.
Inventors
- 👤 Akira Tanaka
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 06:18
CPC Classifications
H; H01; H01J; H01J37/00; H01J37/02; H01J37/04; H01J37/06; H01J37/063
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
181 words
In a thermal emission type electron gun comprising a filament for emitting thermal electrons, an anode arranged to face said filament, a voltage source for supplying high potential difference between said filament and anode, a Wehnelt electrode having an opening therein through which said electrons pass, said Wehnelt electrode arranged between said filament and anode, the side of said Wehnelt electrode facing the anode being convex, and means for supplying a potential to maintain the Wehnelt electrode at a negative potential with respect to the filament, the improvement comprising the distance H between the tip of the filament and the lower rim of the Wehnelt opening satisfying the relation 0.4D < OR = H < OR = 0.8D where D is the diameter of the opening the Wehnelt electrode, and the surface of the Wehnelt electrode near the opening being substantially cylindrical and the surface about the opening facing the filament being substantially cone-shaped and the angle Beta of said coneshaped portion with the axis of the cylindrical opening satisfying the relation 30* < OR = Beta < OR = 90*.
Claim 2
Dependent Claim
181 words
In a thermal emission type electron gun comprising a filament for emitting thermal electrons, an anode arranged to face said filament, a voltage source for supplying high potential difference between said filament and anode, a Wehnelt electrode having an opening therein through which said electrons pass, said Wehnelt electrode arranged between said filament and anode, the side of said Wehnelt electrode facing the anode being convex, and means for supplying a potential to maintain the Wehnelt electrode at a negative potential with respect to the filament, the improvement comprising the distance H between the tip of the filament and the lower rim of the Wehnelt opening satisfying the relation 0.4D < OR = H < OR = 0.8D where D is the diameter of the opening the Wehnelt electrode, and the surface of the Wehnelt electrode near the opening being substantially cylindrical and the surface about the opening facing the filament being substantially cone-shaped and the angle Beta of said coneshaped portion with the axis of the cylindrical opening satisfying the relation 30* < OR = Beta < OR = 90*.
Claim 3
Dependent Claim
36 words
The improvement in a thermal emission type electron gun as set forth in claim 1 in which the height b of said cylindrical surface satisfies the relation 0.2D < or = b < or = 0.8D.
Claim 4
Dependent Claim
175 words
In a thermal emission type electron gun comprising a filament for emitting thermal electrons, an anode arranged to face said filament, a voltage source for supplying high potential different between said filament and anode, a Wehnelt electrode having an opening therein through which said electrons pass, said Wehnelt electrode arranged between said filament and anode, the side of said Wehnelt electrode facing the anode being convex, and means for supplying a potential to maintain the Wehnelt electrode at a negative potential with respect to the filament, the improvement comprising the distance H between the tip of the filament and the lower rim of the Wehnelt opening satisfying the relation 0.4D < or = H < or = 0.8D where D is the diameter of the opening in the Wehnelt electrode and the surface of the Wehnelt electrode near the opening being substantially cylindrical and the surface about the opening facing the filament being substantially cone-shaped and the height b of said cylindrical surface satisfying the relation 0.2D < or = b < or = 0.8D.
Claim 5
Dependent Claim
175 words
In a thermal emission type electron gun comprising a filament for emitting thermal electrons, an anode arranged to face said filament, a voltage source for supplying high potential different between said filament and anode, a Wehnelt electrode having an opening therein through which said electrons pass, said Wehnelt electrode arranged between said filament and anode, the side of said Wehnelt electrode facing the anode being convex, and means for supplying a potential to maintain the Wehnelt electrode at a negative potential with respect to the filament, the improvement comprising the distance H between the tip of the filament and the lower rim of the Wehnelt opening satisfying the relation 0.4D < or = H < or = 0.8D where D is the diameter of the opening in the Wehnelt electrode and the surface of the Wehnelt electrode near the opening being substantially cylindrical and the surface about the opening facing the filament being substantially cone-shaped and the height b of said cylindrical surface satisfying the relation 0.2D < or = b < or = 0.8D.
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) | 1978-06-16 | 1978-12-16 | 1979-06-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-06-16 | 1982-12-16 | 1983-06-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-06-16 | 1986-12-16 | 1987-06-17 | $7700.00 | Window Closed / Lapsed |