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US3676733A
Expired / Lapsed
US
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Circuit arrangement for generating a line frequency parabolically modulated sawtooth current of field frequency through a field deflection coil
Assignee: US Philips Corp
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Filing: 1969-06-13
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Granted: 1972-07-11
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Expires: 1989-06-13
Abstract
Abstract A TV deflection system that includes a circuit for generating a sawtooth field current parabolically modulated at the line frequency in the field deflection coil. The circuit includes a resonant circuit composed of a capacitor and the field deflection coil with a resonant frequency that is approximately one fifth of the line frequency for deriving the parabolic modulation component of line frequency. The sawtooth field deflection generator periodically excites the resonant circuit via a bidirectional electronic switch that is periodically switched in synchronism with the line flyback pulses.
Inventors
- 👤 Hannspeter Eulenberg
- 👤 Gerardus Antonius Wi Veldhoven
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 15:50
CPC Classifications
H; H04; H04N; H04N3/00; H04N3/10; H04N3/16; H04N3/22; H04N3/23; H04N3/237
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
173 words
In a cathode ray tube deflection system having a line deflection coil and a field deflection coil for scanning an electron beam across the screen of the CRT line by line, the improvement comprising a circuit arrangement for generating a sawtooth current of field-frequency in the field deflection coil which current is parabolically modulated at the line frequency, the circuit arrangement comprising a resonant circuit having a capacitor and an inductance means composed mainly of the field deflection coil, said resonant circuit having a resonant frequency which is lower than the line frequency so as to derive said parabolic modulation current component of line frequency, a bidirectional electronic switch capable of conduction in both directions, a source of sawtooth voltage at the field deflection frequency, means connecting said electronic switch in circuit with said voltage source and said resonant circuit, and means for periodically switching said electronic switch at the line frequency so that said resonant circuit is periodically excited from said voltage source through the electronic switch switching at the line frequency.
Claim 2
Dependent Claim
173 words
In a cathode ray tube deflection system having a line deflection coil and a field deflection coil for scanning an electron beam across the screen of the CRT line by line, the improvement comprising a circuit arrangement for generating a sawtooth current of field-frequency in the field deflection coil which current is parabolically modulated at the line frequency, the circuit arrangement comprising a resonant circuit having a capacitor and an inductance means composed mainly of the field deflection coil, said resonant circuit having a resonant frequency which is lower than the line frequency so as to derive said parabolic modulation current component of line frequency, a bidirectional electronic switch capable of conduction in both directions, a source of sawtooth voltage at the field deflection frequency, means connecting said electronic switch in circuit with said voltage source and said resonant circuit, and means for periodically switching said electronic switch at the line frequency so that said resonant circuit is periodically excited from said voltage source through the electronic switch switching at the line frequency.
Claim 3
Dependent Claim
24 words
A circuit arrangement as claimed in claim 1, wherein the resonant frequency of said resonant circuit is approximately one fifth of the line frequency.
Claim 4
Dependent Claim
59 words
A circuit arrangement as claimed in claim 1 wherein the sawtooth voltage source of field frequency is connected to the resonant circuit through the switch which is closed during the flyback period of the sawtooth line deflection voltage said resonant circuit inCluding said capacitor and the field deflection coil connected in parallel arrangement to form a parallel resonant circuit.
Claim 5
Dependent Claim
70 words
A circuit arrangement as claimed in claim 1 wherein the sawtooth voltage source of field frequency is connected to the resonant circuit which includes the field deflection coil and the capacitor connected in series to form a series resonant circuit, a further coil, and means connecting the series arrangement of the bidirectional switch which is closed during the line flyback period and said further coil in parallel with said capacitor.
Claim 6
Dependent Claim
42 words
A circuit arrangement as claimed in claim 4 wherein the parallel arrangement of said capacitor and the bidirectional switch in series with the further coil forms a second resonant circuit with a natural period that is approximately twice the line flyback period.
Claim 7
Dependent Claim
30 words
A circuit arrangement as claimed in claim 1 further comprising a variable coil connected in series with the field deflection coil for adjusting the amplitude of the parabolic current component.
Claim 8
Dependent Claim
19 words
A circuit arrangement as claimed in claim 2 wherein the switch comprises a triac controlled by line flyback pulses.
Claim 9
Dependent Claim
48 words
A circuit arrangement as claimed in claim 1 further comprising a second capacitor and a second inductance means connected in circuit with said capacitor and the field deflection coil to form therewith a second resonant circuit having a natural period that is approximately twice the line flyback period.
Claim 10
Dependent Claim
138 words
In a cathode ray tube deflection system having a line deflection coil and a field deflection coil for scanning an electron beam across the screen of the cathode ray tube, the improvement comprising, a sawtooth voltage source of the field deflection frequency, a bidirectional current switch, a capacitor, means connecting said capacitor and said field deflection coil together to form a resonant circuit having a resonant frequency that is lower than the line deflection frequency of the deflection system, means connecting said switch and said resonant circuit to the terminals of said sawtooth voltage source, and means for switching said switch at the line frequency to excite the resonant circuit from said voltage source via the switch in a manner such that the sawtooth field deflection current in said field coil is parabolically modulated at the line frequency.
Claim 11
Dependent Claim
138 words
In a cathode ray tube deflection system having a line deflection coil and a field deflection coil for scanning an electron beam across the screen of the cathode ray tube, the improvement comprising, a sawtooth voltage source of the field deflection frequency, a bidirectional current switch, a capacitor, means connecting said capacitor and said field deflection coil together to form a resonant circuit having a resonant frequency that is lower than the line deflection frequency of the deflection system, means connecting said switch and said resonant circuit to the terminals of said sawtooth voltage source, and means for switching said switch at the line frequency to excite the resonant circuit from said voltage source via the switch in a manner such that the sawtooth field deflection current in said field coil is parabolically modulated at the line frequency.
Claim 12
Dependent Claim
45 words
A system as claimed in claim 9 wherein said capacitor and field coil are connected together to form a parallel resonant circuit and said connecting means connects said switch and said parallel resonant circuit in series circuit across the terminals of said sawtooth voltage source.
Claim 13
Dependent Claim
51 words
A system as claimed in claim 9 wherein said capacitor and field coil are connected in series across the terminals of said sawtooth voltage source to form a series resonant circuit, a second coil, and wherein said connecting means connects said second coil in series with said switch across the capacitor.
Claim 14
Dependent Claim
36 words
A system as claimed in claim 9 wherein said switch comprises a semiconductor device with a control electrode coupled to the horizontal deflection system so as to be triggered into conduction by the line flyback pulses.
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) | 1975-07-11 | 1976-01-10 | 1976-07-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-07-11 | 1980-01-10 | 1980-07-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-07-11 | 1984-01-10 | 1984-07-11 | $7700.00 | Window Closed / Lapsed |