Patent US4722040A successfully refreshed from Google Patents.
US4722040A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Self-resonant inverter circuit
Assignee: THORN EMI LIGHTING (NZ) Ltd A Co OF NEW ZEALAND
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Filing: 1986-07-07
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Granted: 1988-01-26
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Expires: 2006-07-07
Abstract
Abstract An inverter circuit is provided in which the current can be controlled and which, when used in a gas discharge lamp control circuit, enables dimming and cathode preheat. The inverter comprises two switching means arranged to operate alternately, each controlled by means of a respective secondary element of a transformer, a primary element of the transformer having separate connections to capacitive means and bidirectional threshold means such as a diode arrangement. The bidirectional threshold means and capacitive means are connected as parallel branches to an input of a resonant circuit adapted to receive a load such as a gas discharge lamp. The inverter may further include a variable reactance in the branch including the capacitive means and a sub-circuit may be used to regulate the reactance and thus to control the current drawn by the inverter.
Inventors
- 👤 David P. Ball
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 18:56
CPC Classifications
H; H05; H05B; H05B41/00; H05B41/14; H05B41/26; H05B41/28; H05B41/295; H02; H02M; H02M7/00; H02M7/42; H02M7/44; H02M7/48; H02M7/53; H02M7/537; Y; Y02; Y02B; Y02B70/00; Y02B70/10; Y10; Y10S; Y10S315/00; Y10S315/07
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
138 words
An inverter circuit comprising two input terminals for connecting a unidirectional current supply therebetween, two switching means connected in series across said input terminals, a transformer having two secondary windings, each of the secondary windings being arranged to control the operation of a respective said switching means, and a primary winding, the primary winding having two end connections and a tap connection, the tap connection being intermediate the end connections, said end connections being connected by parallel branches to an input of a resonant circuit adapted to receive a load, one of said branches containing bidirectional threshold means and the other of said branches containing capacitive means, an output of said resonant circuit being connected to said two input terminals via respective further capacitive means, the arrangement being such that, in use, the switching means operate essentially alternately.
Claim 2
Dependent Claim
138 words
An inverter circuit comprising two input terminals for connecting a unidirectional current supply therebetween, two switching means connected in series across said input terminals, a transformer having two secondary windings, each of the secondary windings being arranged to control the operation of a respective said switching means, and a primary winding, the primary winding having two end connections and a tap connection, the tap connection being intermediate the end connections, said end connections being connected by parallel branches to an input of a resonant circuit adapted to receive a load, one of said branches containing bidirectional threshold means and the other of said branches containing capacitive means, an output of said resonant circuit being connected to said two input terminals via respective further capacitive means, the arrangement being such that, in use, the switching means operate essentially alternately.
Claim 3
Dependent Claim
75 words
An inverter circuit comprising two input terminals for connecting a unidirectional current supply therebetween, two switching means arranged to operate alternately, each switching means controlled by means of a respective secondary winding of a transformer, a primary winding of the transformer having separate connections to capacitive means and bidirectional threshold means, the capacitive means and bidirectional threshold means being connected as parallel branches to an input of a resonant circuit adapted to receive a load.
Claim 4
Dependent Claim
75 words
An inverter circuit comprising two input terminals for connecting a unidirectional current supply therebetween, two switching means arranged to operate alternately, each switching means controlled by means of a respective secondary winding of a transformer, a primary winding of the transformer having separate connections to capacitive means and bidirectional threshold means, the capacitive means and bidirectional threshold means being connected as parallel branches to an input of a resonant circuit adapted to receive a load.
Claim 5
Dependent Claim
25 words
An inverter circuit according to claim 1 in which the bidirectional threshold means comprises rectifiers arranged in a bridge formation having a forward voltage drop.
Claim 6
Dependent Claim
13 words
An inverter circuit according to claim 3 in which the rectifiers are diodes.
Claim 7
Dependent Claim
21 words
An inverter circuit according to claim 1 in which the switching means are transistors each shunted by a respective unidirectional means.
Claim 8
Dependent Claim
18 words
An inverter circuit according to claim 1, the branch including the capacitive means further including a variable reactance.
Claim 9
Dependent Claim
39 words
An inverter circuit according to claim 6, the branch including the capacitive means consisting of two parallel arms, one arm comprising a first capacitor and the other of said parallel arms comprising a second capacitor and said variable reactance.
Claim 10
Dependent Claim
18 words
An inverter circuit according to claim 1, the branch including the capacitive means further including a variable resistor.
Claim 11
Dependent Claim
15 words
An inverter circuit according to claim 6 further including a sub-circuit to regulate the reactance.
Claim 12
Dependent Claim
22 words
An inverter circuit according to claim 6, in which the variable reactance is provided by the primary winding of a further transformer.
Claim 13
Dependent Claim
30 words
An inverter circuit according to claim 9 in which the sub-circuit controls the current through a secondary winding of said further transformer and hence controls the reactance of the first.
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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) | 1991-01-25 | 1991-07-27 | 1992-01-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-01-25 | 1995-07-27 | 1996-01-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-01-25 | 1999-07-27 | 2000-01-26 | $7700.00 | Window Closed / Lapsed |