US3882356A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Level shifter transistor for a fluorescent lamp ballast system
Assignee: Texas Instruments Inc
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Filing: 1973-12-20
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Granted: 1975-05-06
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Expires: 1993-12-20
Abstract
Abstract An improved arrangement for coupling logic drivers to power devices in a solid-state fluorescent lamp ballast system in which the necessary isolation between the high voltage power devices in the solid-state ballast system and the logic drivers is obtained by using level shifter transistors in which the power switch to be isolated is selected to be a PNP transistor and the transistor for driving and isolating the PNP transistor is an NPN level shifter transistor.
Inventors
- 👤 Robert A Stehlin
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 15:05
CPC Classifications
H; H05; H05B; H05B41/00; H05B41/14; H05B41/36; H05B41/38; H05B41/39; H05B41/392; H05B41/30; Y; Y10; Y10S; Y10S315/00; Y10S315/05; Y10S315/07
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
123 words
In a solid-state ballast system for a fluorescent lamp wherein first and second switching transistors are connected in series across the output of a full wave rectifier, with the connection between said transistors being provided to the lamp, and wherein only one of said transistors is ever on at one time, the switching of said transistors being controlled by logic circuits, which logic circuits are only capable of withstanding a low voltage, means to provide isolation between the logic circuits and said transistors comprising: a level shifter transistor having its emitter grounded and its collector output coupled as a control input to said transistors with the output of one of said logic circuits being coupled to the base of said level shifter transistor.
Claim 2
Dependent Claim
123 words
In a solid-state ballast system for a fluorescent lamp wherein first and second switching transistors are connected in series across the output of a full wave rectifier, with the connection between said transistors being provided to the lamp, and wherein only one of said transistors is ever on at one time, the switching of said transistors being controlled by logic circuits, which logic circuits are only capable of withstanding a low voltage, means to provide isolation between the logic circuits and said transistors comprising: a level shifter transistor having its emitter grounded and its collector output coupled as a control input to said transistors with the output of one of said logic circuits being coupled to the base of said level shifter transistor.
Claim 3
Dependent Claim
17 words
The invention according to claim 1 wherein said level shifter transistor comprises an NPN level shifter transistor.
Claim 4
Dependent Claim
46 words
The invention according to claim 2 wherein: a. said first switching transistor is a PNP transistor having its emitter coupled to the high output of the rectifier; and b. the collector of said NPN level shifter transistor is coupled to the base of said PNP transistor.
Claim 5
Dependent Claim
44 words
The invention according to claim 3 wherein the collector of said NPN level shifter transistor is coupled to the high side of said rectifier through first and second series resistors with the base of said PNP transistor coupled to the junction of said resistors.
Claim 6
Dependent Claim
20 words
The invention according to claim 3 wherein said first switching transistor is connected in a Darlington pair of PNP transistors.
Claim 7
Dependent Claim
32 words
The invention according to claim 3 wherein said second switching transistor comprises an NPN transistor having its collector coupled to the collector of said PNP transistor and its emitter coupled to ground.
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) | 1978-05-05 | 1978-11-04 | 1979-05-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-05-05 | 1982-11-04 | 1983-05-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-05-05 | 1986-11-04 | 1987-05-06 | $7700.00 | Window Closed / Lapsed |