Patent US3916254A successfully refreshed from Google Patents.
US3916254A
Expired / Lapsed
US
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Adjustable pincushion correction circuit
Assignee: Thomas International Corp
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Filing: 1974-02-13
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Granted: 1975-10-28
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Expires: 1994-02-13
Abstract
Abstract In a television receiver, a north-south pincushion correction circuit includes a switching transistor having a variable on-time controlled by a variable DC bias to phase shift a horizontal sawtooth coupled to a differential amplifier. A pair of diodes, coupled to the outputs of the differential amplifier, are maintained in the conduction region under control of a vertical sawtooth signal to generate a pincushion correction signal which is superimposed on the vertical sawtooth. The resultant is amplified by a vertical amplifier and drives vertical yoke coils to a sub-multiple of the horizontal sawtooth frequency.
Inventors
- 👤 Frederick E Worster
- 👤 Raymond T Kostecki
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 14:52
CPC Classifications
H; H04; H04N; H04N3/00; H04N3/10; H04N3/16; H04N3/22; H04N3/23; H04N3/233
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
129 words
In a television receiver having a sweep source for supplying a sweep signal to a first deflection coil, a pincushion correction circuit, comprising: circuit means having an input terminal and a pair of output terminals, said input terminal being coupled to a pulse producing means, said circuit means operating to generate at its output terminals a pair of opposed signals of mirror symmetry and a variable impedance means having two terminals connected to the output terminals, respectively, of the circuit means and a third terminal connected to the sweep source, said impedance means having an impedance value related to the magnitude of the sweep signal whereby the impedance means variably loads the sweep source and a pincushion correction signal of continuously varying proportions is superimposed on the sweep signal.
Claim 2
Dependent Claim
129 words
In a television receiver having a sweep source for supplying a sweep signal to a first deflection coil, a pincushion correction circuit, comprising: circuit means having an input terminal and a pair of output terminals, said input terminal being coupled to a pulse producing means, said circuit means operating to generate at its output terminals a pair of opposed signals of mirror symmetry and a variable impedance means having two terminals connected to the output terminals, respectively, of the circuit means and a third terminal connected to the sweep source, said impedance means having an impedance value related to the magnitude of the sweep signal whereby the impedance means variably loads the sweep source and a pincushion correction signal of continuously varying proportions is superimposed on the sweep signal.
Claim 3
Dependent Claim
58 words
The pincushion correction circuit of claim 1 wherein the variable impedance means comprises a pair of diodes coupled respectively between the pair of output terminals and a summing junction, means coupling the junction to the sweep source for driving the diodes with the sweep signal to cause the diodes to have impedance values related to the sweep signal.
Claim 4
Dependent Claim
54 words
The pincushion correction circuit of claim 2 including a source of reference ground, and wherein the sweep source supplies a sawtooth sweep signal having a sawtooth varIation with respect to ground, and including a pair of resistors shunting to ground the pair of diodes at sides opposite the sides connected to the summing junction.
Claim 5
Dependent Claim
88 words
The pincushion correction circuit of claim 1 wherein the sweep signal has a sawtooth waveform and the variable impedance means produces a pincushion correction signal at approximately the frequency of the pulse producing means and including an amplifier responsive to the composite output signals of the sweep source, said amplifier being coupled to the output circuit for the deflection coil and including a network tuned to a frequency harmonically related to the frequency of the pulse producing means to produce ringing in response to the pincushion correction signal.
Claim 6
Dependent Claim
48 words
The pincushion correction circuit of claim 1 including a phase shifting circuit coupled between the pulse producing means and the input to the circuit means and including an element adjustable for shifting the phase of the opposed signals to thereby vary the phase of the pincushion correction signal.
Claim 7
Dependent Claim
81 words
The pincushion correction circuit of claim 5 wherein the pulse producing means supplies a pulse signal, means for integrating the pulse signal to derive a sawtooth signal, the phase shifting circuit includes a variable bias source having a variable DC bias in response to the adjustable element, a semiconductor switching device driven into conduction when the sawtooth signal and the variable DC bias are in predetermined relationship, and means coupling the semiconductor switching device to the input of the circuit means.
Claim 8
Dependent Claim
121 words
The pincushion correction circuit of claim 6 wherein the circuit means comprises a differential amplifier including a pair of three terminal semiconductor devices, means connecting a first terminal of each semiconductor device to a common resistor, means coupling the second terminals of the pair of semiconductor devices to respective load resistors, means coupling the third terminal of the first semiconductor device to the phase shifting circuit in order to form the input to the differential amplifier, means coupling the third terminal of the other semiconductor device to a reference source, and the variable impedance means is coupled to the second terminals of the pair of semiconductor devices to receive the pair of opposed signals generated by the pair of semiconductor devices.
Claim 9
Dependent Claim
129 words
In a television receiver having a first sawtooth sweep source for supplying a first sawtooth sweep signal to a first deflection coil and a source of sawtooth waves in time synchronism with a second sweep signal, a pincushion correction circuit, comprising: a switching device; a variable bias source for producing a DC bias of variable magnitude; phase shifting means driving the switching device into conduction when the sawtooth wave and the variable magnitude DC bias have a predetermined relationship therebetween, a change in the magnitude of the DC bias changing the conduction time of the switching device with respect to the sawtooth wave; and correction means coupled to the switching device for generating a pincushion correction signal having a phase controllable by the conduction time of the switching device.
Claim 10
Dependent Claim
129 words
In a television receiver having a first sawtooth sweep source for supplying a first sawtooth sweep signal to a first deflection coil and a source of sawtooth waves in time synchronism with a second sweep signal, a pincushion correction circuit, comprising: a switching device; a variable bias source for producing a DC bias of variable magnitude; phase shifting means driving the switching device into conduction when the sawtooth wave and the variable magnitude DC bias have a predetermined relationship therebetween, a change in the magnitude of the DC bias changing the conduction time of the switching device with respect to the sawtooth wave; and correction means coupled to the switching device for generating a pincushion correction signal having a phase controllable by the conduction time of the switching device.
Claim 11
Dependent Claim
52 words
The pincushion correction circuit of claim 8 wherein the switching device comprises a semiconductor switching device, the phase shifting means driving the semiconductor switching device into conduction when the first sawtooth wave crosses the magnitude of the DC bias thereby producing a pulse having a phase controllable by the variable bias source.
Claim 12
Dependent Claim
91 words
The pincushion correction circuit of claim 9 wherein the semiconductor switching device comprises a transistor having first, second and third terminals, the phase shifting means connects the sawtooth wave to the first terminal of the transistor, means coupling the variable bias source to the first terminal of the transistor, the correction means includes an integrator coupled to the third terminal and which is responsive to the pulSe produced by the transistor for generating a sawtooth signal synchronized therewith, and means for modifying the sawtooth signal to produce the pincushion correction signal.
Claim 13
Dependent Claim
67 words
The pincushion correction circuit of claim 10 wherein the modifying means comprises a differential amplifier having an input coupled to the integrator and a pair of outputs carrying a pair of opposed waves of mirror symmetry, and means for continuously loading and unloading the first sawtooth sweep source in varying proportions in response to the sweep signal and the opposed waves to produce the pincushion correction signal.
Claim 14
Dependent Claim
61 words
The pincushion correction circuit of claim 8 wherein the source of sawtooth waves comprises an output winding of a flyback transformer for generating a horizontal flyback pulse, an integrator coupled to the flyback transformer winding for integrating the flyback pulse to generate a sawtooth waveform corresponding to the horizontal deflection sawtooth wave, and means coupling the integrator to the switching device.
Claim 15
Dependent Claim
109 words
The pincushion correction circuit of claim 8 including a source of reference potential, a positive DC source for supplying a fixed DC signal which is positive with respect to the reference potential, a negative DC source for supplying a fixed DC signal which is negative with respect to the reference potential, and the variable bias source includes a voltage divider coupled between the positive and negative DC sources and including a variable resistance for producing a DC bias of variable polarity and amplitude with respect to the reference potential, and the sawtooth wave source supplies the sawtooth wave with positive and negative polarities with respect to the reference potential.
Claim 16
Dependent Claim
80 words
The pincushion correction circuit of claim 8 wherein the correction means includes a differential amplifier having a pair of outputs carrying a pair of opposed waves of mirror symmetry and of a phase controllable by the variable bias source, and a pair of diodes coupled to the pair of outputs and operated in the non-linear conductive region for producing a variable impedance in response to the magnitude of the first sweep signal in order to produce the pincushion correction signal.
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) | 1978-10-27 | 1979-04-28 | 1979-10-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-10-27 | 1983-04-28 | 1983-10-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-10-27 | 1987-04-28 | 1987-10-28 | $7700.00 | Window Closed / Lapsed |