US4281275A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Circuit for driving deflection coil
Assignee: Allard Way Holdings Ltd
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Filing: 1979-09-07
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Granted: 1981-07-28
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Expires: 1999-09-07
Abstract
Abstract A circuit for driving a deflection coil comprising a capacitor (3) in series with the coil (2), a circuit (1) which drives a saw-tooth waveform current through the coil and capacitor, and a switchable resonant circuit (5, 6, 7, 8, 9) which generates across the capacitor a saw-tooth waveform voltage equal and opposite to the voltage drop attributable to a resistive component (4) of the capacitor/coil series circuit, thereby to effect loss correction.
Inventors
- 👤 Peter Chapman
- 👤 Martin W. Redfern
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 16:50
CPC Classifications
H; H03; H03K; H03K4/00; H03K4/06; H03K4/08; H03K4/90; H03K4/48; H03K4/60; H03K4/62
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
78 words
A circuit for driving a deflection coil comprising: a capacitor forming a series L-C circuit with the deflection coil; a drive circuit to produce a current of sawtooth waveform through the series L-C circuit; and a switchable resonant circuit connected across the capacitor of the said series L-C circuit to produce across said capacitor a saw-tooth waveform voltage component which is substantially equal and opposite to the voltage drop attributable to a resistive component of the L-C circuit.
Claim 2
Dependent Claim
78 words
A circuit for driving a deflection coil comprising: a capacitor forming a series L-C circuit with the deflection coil; a drive circuit to produce a current of sawtooth waveform through the series L-C circuit; and a switchable resonant circuit connected across the capacitor of the said series L-C circuit to produce across said capacitor a saw-tooth waveform voltage component which is substantially equal and opposite to the voltage drop attributable to a resistive component of the L-C circuit.
Claim 3
Dependent Claim
129 words
A circuit according to claim 1 wherein said switchable resonant circuit comprises a capacitor, a first inductor and a switch means connected in series across the capacitor of said L-C circuit, and a second inductor connected in series with a power source across the series connection of said first inductor and said switch means, the capacitor of the L-C circuit together with the capacitor and second inductor of said switchable resonant circuit forming a circuit which resonates at substantially the same frequency as the L-C circuit, and the capacitor of the L-C circuit together with the capacitor and the first inductor of the switchable resonant circuit forming, with the switch means closed, a resonant circuit having a half period substantially equal to the flyback period of the saw-tooth waveform.
Claim 4
Dependent Claim
19 words
A circuit according to claim 2 wherein said power source comprises a capacitor in parallel with a current source.
Claim 5
Dependent Claim
57 words
A circuit according to claim 1 including a sensing circuit for sensing the current flowing in the inductor of the L-C circuit; and a control circuit to control the amplitude of said saw-tooth waveform voltage component in response to the output of the sensing circuit so as to produce substantial symmetry of the sensed inductor saw-tooth current.
Claim 6
Dependent Claim
18 words
A circuit according to claim 4 wherein the sensing circuit comprises a current transformer having a resistive load.
Claim 7
Dependent Claim
24 words
A circuit according to claim 4 wherein said control circuit comprises a symmetry error detecting circuit responsive to the output of the sensing circuit.
Claim 8
Dependent Claim
42 words
A circuit according to claim 6 wherein said symmetry error detecting circuit comprises a peak detector circuit for detecting the positive and negative peaks of the sensing circuit output and a summing circuit responsive to the output of the peak detector circuit.
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) | 1984-07-27 | 1985-01-26 | 1985-07-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1988-07-27 | 1989-01-26 | 1989-07-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1992-07-27 | 1993-01-26 | 1993-07-28 | $7700.00 | Window Closed / Lapsed |