US3889156A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Double tuned retrace driven horizontal deflection circuit
Assignee: Thomas International Corp
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Filing: 1973-09-21
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Granted: 1975-06-10
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Expires: 1993-09-21
Abstract
Abstract A horizontal scanning circuit for a television receiver includes a capacitor in series between a voltage supply and a primary winding of a transformer having a secondary winding coupled to a deflection winding. During the trace period, the capacitor is charged through the series circuit. During the retrace period, a horizontal sync pulse enables a thyristor to discharge the capacitor through an inductor in shunt with the charge circuit. The capacitor is resonant with the inductance of the transformer primary winding at a fundamental frequency related to the retrace period, and is resonant with the inductance of the transformer primary winding and reflected inductance of the transformer secondary winding at a higher frequency such as the third harmonic to decrease the total current flow at the end of the retrace period to automatically disable the thyristor.
Inventors
- 👤 Manohar L Arya
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 08:40
CPC Classifications
H; H03; H03K; H03K4/00; H03K4/06; H03K4/08; H03K4/83; H03K4/84
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
164 words
A scanning circuit for producing in a deflection winding a generally sawtooth deflection current having a trace period and a retrace period, comprising: a voltage source; a reactive impedance for storing energy; coupling means for supplying current to said deflection winding; a charge circuit for charging the reactive impedance from said voltage source during the trace period; a semiconDuctor device having a first state, and a second state occurring in response to a predetermined electrical flow; a discharge circuit energized by said semiconductor device during the retrace period for discharging the reactive impedance through said coupling means to produce in said deflection winding a generally sawtooth current, said discharge circuit being resonant at a first frequency related to the retrace period for generating a fundamental current flow through said semiconductor device and resonant at a second frequency higher than the first frequency for generating at the end of a said retrace period a secondary current flow which switches said device to said first state.
Claim 2
Dependent Claim
164 words
A scanning circuit for producing in a deflection winding a generally sawtooth deflection current having a trace period and a retrace period, comprising: a voltage source; a reactive impedance for storing energy; coupling means for supplying current to said deflection winding; a charge circuit for charging the reactive impedance from said voltage source during the trace period; a semiconDuctor device having a first state, and a second state occurring in response to a predetermined electrical flow; a discharge circuit energized by said semiconductor device during the retrace period for discharging the reactive impedance through said coupling means to produce in said deflection winding a generally sawtooth current, said discharge circuit being resonant at a first frequency related to the retrace period for generating a fundamental current flow through said semiconductor device and resonant at a second frequency higher than the first frequency for generating at the end of a said retrace period a secondary current flow which switches said device to said first state.
Claim 3
Dependent Claim
25 words
The scanning circuit of claim 1 wherein said discharge circuit is resonant at a second frequency which comprises an odd harmonic of the first frequency.
Claim 4
Dependent Claim
33 words
The scanning circuit of claim 1 wherein said coupling means comprises a transformer having a primary winding connected in series with said reactive impedance and a secondary winding connected with said deflection winding.
Claim 5
Dependent Claim
40 words
The scanning circuit of claim 3 wherein said reactive impedance comprises a capacitor, and said charge circuit includes an inductor in series with the capacitor and the primary winding of the transformer for charging the capacitor from the voltage source.
Claim 6
Dependent Claim
52 words
The scanning circuit of claim 3 wherein said reactive impedance comprises a capacitor, and said discharge circuit includes an inductor, in series with said capacitor and said primary winding when said thyristor is in its second state, said inductor, capacitor, and primary winding being resonant at both said first and second frequencies.
Claim 7
Dependent Claim
29 words
The scanning circuit of claim 3 including a diode coupled between said deflection winding and said voltage source and forming a return path for current from said deflection winding.
Claim 8
Dependent Claim
68 words
The scanning circuit of claim 1 wherein said semiconductor device has the first power terminal, a second power terminal, and a gate terminal, a source of horizontal sync pulses, and means coupling said horizontal sync pulse source to said gate terminal to drive said semiconductor device into a conductive state, corresponding to said first state, during the retrace period to discharge the energy stored in the reactive impedance.
Claim 9
Dependent Claim
53 words
The scanning circuit of claim 1 wherein said reactive impedance comprises a capacitor, said charge circuit includes a first inductor in series between said voltage source and said capacitor, and said discharge circuit eliminates said first inductor and substitutes a second inductor coupled to a junction between said first inductor and said capacitor.
Claim 10
Dependent Claim
44 words
The scanning circuit of claim 8 wherein said coupling means comprises a transformer having a primary winding and a secondary winding, said primary winding being in both said charge circuits and said discharge circuit, and means coupling said secondary winding to said deflection winding.
Claim 11
Dependent Claim
41 words
The scanning circuit of claim 9 wherein said means coupling said secondary winding includes a second capacitor coupled between said secondary winding and said deflection winding, and a diode and capacitor network coupled between said second capacitor and said voltage source.
References Cited (Backward Citations)
US3229150A
Cited
US3189782A
Cited
US3210601A
Cited
US3323001A
Cited
US3500116A
Cited
US3466496A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-06-09 | 1978-12-09 | 1979-06-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-06-09 | 1982-12-09 | 1983-06-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-06-09 | 1986-12-09 | 1987-06-10 | $7700.00 | Window Closed / Lapsed |