Patent US3757144A successfully refreshed from Google Patents.
US3757144A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Its emitter and base electrodes switching circuit transistor with a delayed turn on diode coupled to
Assignee: US Philips Corp
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Filing: 1972-01-14
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Granted: 1973-09-04
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Expires: 1992-01-14
Abstract
Abstract A switching circuit has a first transistor and a transformer which apply a switching signal to a second transistor. A long turn on time diode is connected to the second transistor base and emitter electrodes, but in an opposite conductivity direction, to prevent excessive power dissipation during the switching off period. A second diode can be connected between the transformer and the emitter to prevent loading of the transformer. Likewise, a coil can be connected between the transformer and the base to improve turn off performance.
Inventors
- 👤 W Hetterscheid
- 👤 Vries H De
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 13:34
CPC Classifications
H; H03; H03K; H03K4/00; H03K4/06; H03K4/08; H03K4/48; H03K4/60; H03K4/62; H03K4/64; H03K17/00; H03K17/04; H03K17/041; H03K17/0412; H03K17/04126; H03K5/00; H03K5/01; H03K5/02
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
113 words
A circuit comprising a transistor having emitter, base, and collector electrodes said base and emitter electrodes thereby defining a base-emitter junction having a conducting direction through said junction; a load impedance coupled to said collector; means for applying a switching signal to said base and emitter electrodes, whereby said transistor has alternate on and off periods; and means for prevenTing excessive power dissipation in the base-emitter junction of said transistor during switching from said on to said off periods including a diode having a turn on time greater than one microsecond coupled across said base and emitter electrodes in a conducting direction opposite to that of said conducting direction of the base-emitter junction.
Claim 2
Dependent Claim
113 words
A circuit comprising a transistor having emitter, base, and collector electrodes said base and emitter electrodes thereby defining a base-emitter junction having a conducting direction through said junction; a load impedance coupled to said collector; means for applying a switching signal to said base and emitter electrodes, whereby said transistor has alternate on and off periods; and means for prevenTing excessive power dissipation in the base-emitter junction of said transistor during switching from said on to said off periods including a diode having a turn on time greater than one microsecond coupled across said base and emitter electrodes in a conducting direction opposite to that of said conducting direction of the base-emitter junction.
Claim 3
Dependent Claim
20 words
A circuit as claimed in claim 1 further comprising a second diode coupled between said applying means and said emitter.
Claim 4
Dependent Claim
17 words
A circuit as claimed in claim 2 further comprising a resistor shunt coupled to said second diode.
Claim 5
Dependent Claim
18 words
A circuit as claimed in claim 1 further comprising a diode coupled to said emitter and collector electrodes.
Claim 6
Dependent Claim
19 words
A circuit as claimed in claim 1 further comprising a coil coupled between said applying means and said base.
Claim 7
Dependent Claim
17 words
A circuit as claimed in claim 1 wherein said turn on time is less than two microseconds.
Claim 8
Dependent Claim
15 words
A circuit as claimed in claim 1 wherein said transistor is a high voltage type.
Claim 9
Dependent Claim
18 words
A circuit as claimed in claim 1 wherein said load impedance comprises a television line frequency deflection coil.
Claim 10
Dependent Claim
24 words
A circuit as claimed in claim 1 wherein said emitter is a common electrode with respect to said applying means and said load impedance.
Claim 11
Dependent Claim
55 words
A circuit as claimed in claim 1 wherein said applying means comprises a second transistor having emitter, base and collector electrodes, said base being coupled to receive said switching signal; and a transformer having a primary coupled to said collector and emitter electrodes and a secondary coupled to said first transistor base and emitter electrodes.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-09-03 | 1977-03-05 | 1977-09-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-09-03 | 1981-03-05 | 1981-09-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-09-03 | 1985-03-05 | 1985-09-04 | $7700.00 | Window Closed / Lapsed |