US3748531A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Circuit arrangement for generating in a picture display device a sawtooth current of line frequency having an amplitude varying at field frequency
Assignee: US Philips Corp
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Filing: 1970-05-27
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Granted: 1973-07-24
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Expires: 1990-05-27
Abstract
Abstract A circuit arrangement for generating by means of a modulator in a colour picture display device a sawtooth correction current of line frequency flowing through the line deflection coils and having an amplitude varying at field frequency for the purpose of obtaining a better colour superposition in the corners of the screen of the display tube, comprising means to add an additional correction current which flows in the same direction as the first mentioned current and which is proportional to the third power of both the line and the field deflection currents. Said means may be a saturable coil or a resonant circuit which is tuned to a frequency which lies between the like frequency and twice the value thereof. In the latter case the voltage present across the circuit may be used for correcting the North-South pincushion distortion. Also, the modulator is controlled by an amplifier comprising a linear and a voltage-dependent resistor which ensure that a third-power component is added also to said field deflection current.
Inventors
- 👤 A Boekhorst
- 👤 J Rietveld
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 21:05
CPC Classifications
H; H04; H04N; H04N3/00; H04N3/10; H04N3/16; H04N3/22; H04N3/23; H04N3/233
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
105 words
A distortion correction circuit for line and field deflection coils of a display tube, said circuit comprising line and field deflection generator means coupled to said coils respestively for producing line and field deflection signals respectively; a modulator means for providing a line frequency first correction current having a field frequency varying amplitude to at least one of said coils; and means for supplying an additional correction current distinct from said deflection signals that is a thrid power function of at least one of said deflection signals and for applying it to said one deflection coil in the same direction as said first correction current.
Claim 2
Dependent Claim
105 words
A distortion correction circuit for line and field deflection coils of a display tube, said circuit comprising line and field deflection generator means coupled to said coils respestively for producing line and field deflection signals respectively; a modulator means for providing a line frequency first correction current having a field frequency varying amplitude to at least one of said coils; and means for supplying an additional correction current distinct from said deflection signals that is a thrid power function of at least one of said deflection signals and for applying it to said one deflection coil in the same direction as said first correction current.
Claim 3
Dependent Claim
29 words
A circuit as claimed in claim 1 wherein said supplying means comprises a non-linear inductor series coupled to said modulator and having an inductance that decreases with increasing current.
Claim 4
Dependent Claim
47 words
A circuit as claimed in claim 1 wherein said supplying means comprises a tuned circuit including an inductor and a capacitor parallel coupled thereto, said circuit being tuned to a frequency between the line frequency and twice the line frequency and being series coupled to said modulator.
Claim 5
Dependent Claim
36 words
A circuit as claimed in claim 3 wherein said inductor comprises a transformer primary, said transformer including a secondary; and further comprising means coupled to said secondary for correcting North-South pincushion distortion in said display tube.
Claim 6
Dependent Claim
68 words
A circuit as claimed in claim 1 wherein said modulator comprises diode switch means operating at the line frequency for coupling during the line scan time the field generator to a resonant circuit having a period twice the line flyback period, said resonant circuit including a capacitor and said line deflection coil; and further comprising a coil coupled in series between said line generator and said line coil.
Claim 7
Dependent Claim
16 words
A circuit as claimed in claim 5 further comprising a resistor series coupled to said capacItor.
Claim 8
Dependent Claim
73 words
A circuit as claimed in claim 5 further comprising a series circuit including in order a first capacitor, a pair of diodes that are non-conducting during the line flyback time, and a second capacitor, said series circuit being parallel coupled to said coil; and an inductance capacitance parallel resonant circuit coupled to the junction of the diodes, said circuit being resonant at a frequency between the line frequency and twice the line frequency.
Claim 9
Dependent Claim
61 words
A circuit as claimed in claim 1 further comprising amplifier means for applying said field signal to said modulator, said amplifier including a complementary pair of transistors adapted to receive a negative feedback network having an input coupled to the output electrodes of said transistors for receiving a zero average signal, said network comprising fixed and voltage dependent resistors coupled thereto.
Claim 10
Dependent Claim
32 words
A circuit as claimed in claim 1 further comprising a circuit coupled between said modulator and said field generator, said circuit comprising a fixed and a voltage dependent resistor parallel coupled thereto.
Claim 11
Dependent Claim
25 words
A circuit as claimed in claim 1 further comprising North-South pincushion correction means for adding a sinusoidal current of line frequency to said correction current.
Claim 12
Dependent Claim
21 words
A circuit as claimed 1 wherein said additional correction current is a third power function of both of said deflection signals.
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) | 1976-07-23 | 1977-01-22 | 1977-07-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-07-23 | 1981-01-22 | 1981-07-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-07-23 | 1985-01-22 | 1985-07-24 | $7700.00 | Window Closed / Lapsed |