US4590407A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Scale illumination lamp control circuit for an oscilloscope
Assignee: Tektronix Inc
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Filing: 1984-02-03
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Granted: 1986-05-20
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Expires: 2004-02-03
Abstract
Abstract A lamp control circuit particularly suited for scale illumination in cathode-ray tube display devices provides stabilized lamp control impervious to temperature fluctuations for either constant or pulsed operating modes.
Inventors
- 👤 Lloyd R. Bristol
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 13:27
CPC Classifications
H; H05; H05B; H05B39/00; H05B39/04
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
85 words
A lamp control circuit, comprising: a series connection of a lamp and the primary current path of a transistor connected between predetermined voltage sources; a series connection of a potentiometer and a semiconductor junction connected between the collector and emitter of said transistor; and a resistor coupled between the wiper arm of said potentiometer and the base of said transistor; wherein said resistor and a selectable part of said potentiometer form a negative feedback path from the collector of said transistor to the base thereof.
Claim 2
Dependent Claim
85 words
A lamp control circuit, comprising: a series connection of a lamp and the primary current path of a transistor connected between predetermined voltage sources; a series connection of a potentiometer and a semiconductor junction connected between the collector and emitter of said transistor; and a resistor coupled between the wiper arm of said potentiometer and the base of said transistor; wherein said resistor and a selectable part of said potentiometer form a negative feedback path from the collector of said transistor to the base thereof.
Claim 3
Dependent Claim
18 words
A lamp control circuit in accordance with claim 1 wherein said transistor comprises a plurality of parallel transistors.
Claim 4
Dependent Claim
19 words
A lamp control circuit in accordance with claim 1 wherein said transistor and semiconductor junction comprises Darlington transistor pairs.
References Cited (Backward Citations)
FR615013A
Cited
US3404311A
Cited
US3906292A
Cited
US3903454A
Cited
US3938000A
Cited
US4029991A
Cited
US4321509A
Cited
US4358714A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1989-05-19 | 1989-11-18 | 1990-05-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1993-05-19 | 1993-11-18 | 1994-05-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1997-05-19 | 1997-11-18 | 1998-05-20 | $7700.00 | Window Closed / Lapsed |