US3810025A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Field emission type electron gun
Assignee: Jeol Ltd
•
Filing: 1972-04-18
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Granted: 1974-05-07
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Expires: 1992-04-18
Abstract
Abstract This invention relates to a field emission type electron gun capable of protecting the emitter tip from damage when electrical breakdown occurs in the gun chamber. The preferred embodiments incorporate circuitry for decreasing the impedance between the emitter and its associated electrode when electrical breakdown occurs.
Inventors
- 👤 R Aihara
- 👤 S Ota
- 👤 N Kobayashi
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 03:23
CPC Classifications
H; H01; H01J; H01J37/00; H01J37/02; H01J37/24; H01J37/241; H01J3/00; H01J3/02; H01J3/021; H01J37/04; H01J37/06; H01J37/073; H02; H02H; H02H7/00; H02H7/20
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
233 words
A field emission type electron gun device comprising: i. an emitter for emitting an electron beam, ii. an anode for accelerating the electron beam, iii. a high voltage source for supplying negative high potential to said emitter in order to accelerate said electron beam, iv. an electrode located between said emitter and said anode. v. a voltage source for generating a potential difference between said electrode and said emitter in order to generate a strong electric field in the vicinity of said emitter tip, and vi. a protection means for preventing the generation of an unusually high potential difference between said emitter and said electrode comprising a switching circuit for rapidly decreasing the impedance of said protection means in the event that the voltage between said emitter and said electrode increases beyond the firing voltage of The switching circuit, and vii. means for heating the emitter comprising a first and second isolation transformer, the secondary of the first transformer being in series with the primary of the second transformer, the primary of the first transformer being connected to an AC voltage supply, the secondary of the second transformer being in series with the emitter of the electron gun, the high voltage supply being connected to the circuit between the said first and second transformers and the emitter being connected through a high value resistor to the circuit between said first and second transformers.
Claim 2
Dependent Claim
233 words
A field emission type electron gun device comprising: i. an emitter for emitting an electron beam, ii. an anode for accelerating the electron beam, iii. a high voltage source for supplying negative high potential to said emitter in order to accelerate said electron beam, iv. an electrode located between said emitter and said anode. v. a voltage source for generating a potential difference between said electrode and said emitter in order to generate a strong electric field in the vicinity of said emitter tip, and vi. a protection means for preventing the generation of an unusually high potential difference between said emitter and said electrode comprising a switching circuit for rapidly decreasing the impedance of said protection means in the event that the voltage between said emitter and said electrode increases beyond the firing voltage of The switching circuit, and vii. means for heating the emitter comprising a first and second isolation transformer, the secondary of the first transformer being in series with the primary of the second transformer, the primary of the first transformer being connected to an AC voltage supply, the secondary of the second transformer being in series with the emitter of the electron gun, the high voltage supply being connected to the circuit between the said first and second transformers and the emitter being connected through a high value resistor to the circuit between said first and second transformers.
Claim 3
Dependent Claim
261 words
A field emission type electron gun device comprising: i. an emitter for emitting electron beam, ii. an anode for accelerating the electron beam, iii. a high voltage source for supplying negative high potential to said emitter in order to accelerate said electron beam, iv. a first electrode located between said emitter and said anode, v. a voltage source for generating a potential difference between said first electrode and said emitter in order to generate a strong electric field in the vicinity of said emitter tip, vi. a second electrode located between said first electrode and said anode, vii. a D.C. voltage source for supplying a potential to said secondary electrode, and viii. a protection means for preventing the generation of an unusually high potential difference between said second electrode and said emitter comprising a switching circuit for rapidly decreasing the impedance of said protection means in the event that the voltage between said emitter and said second electrode increases beyond the firing voltage of the switching circuit, and ix. means for heating the emitter comprising a first and second isolation transformer, the secondary of the first transformer being in series with the primary of the second transformer, the primary of the first transformer being connected to an A.C. voltage supply, the secondary of the second transformer being in series with the emitter of the electron gun, the high voltage supply being connected to the circuit between the said first and second transformers and the emitter being connected through a high value resistor to the circuit between said first and second transformers.
Claim 4
Dependent Claim
261 words
A field emission type electron gun device comprising: i. an emitter for emitting electron beam, ii. an anode for accelerating the electron beam, iii. a high voltage source for supplying negative high potential to said emitter in order to accelerate said electron beam, iv. a first electrode located between said emitter and said anode, v. a voltage source for generating a potential difference between said first electrode and said emitter in order to generate a strong electric field in the vicinity of said emitter tip, vi. a second electrode located between said first electrode and said anode, vii. a D.C. voltage source for supplying a potential to said secondary electrode, and viii. a protection means for preventing the generation of an unusually high potential difference between said second electrode and said emitter comprising a switching circuit for rapidly decreasing the impedance of said protection means in the event that the voltage between said emitter and said second electrode increases beyond the firing voltage of the switching circuit, and ix. means for heating the emitter comprising a first and second isolation transformer, the secondary of the first transformer being in series with the primary of the second transformer, the primary of the first transformer being connected to an A.C. voltage supply, the secondary of the second transformer being in series with the emitter of the electron gun, the high voltage supply being connected to the circuit between the said first and second transformers and the emitter being connected through a high value resistor to the circuit between said first and second transformers.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-05-06 | 1977-11-05 | 1978-05-07 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-05-06 | 1981-11-05 | 1982-05-07 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-05-06 | 1985-11-05 | 1986-05-07 | $7700.00 | Window Closed / Lapsed |