Electric lamp and discharge devices: systems – Cathode ray tube circuits – Cathode-ray deflections circuits
Reexamination Certificate
2000-09-08
2001-11-20
Philogene, Haissa (Department: 2821)
Electric lamp and discharge devices: systems
Cathode ray tube circuits
Cathode-ray deflections circuits
C315S370000, C315S396000
Reexamination Certificate
active
06320332
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to a deflection circuit of a video display apparatus. In particular, the invention relates to an inner East-West (E-W) pincushion correction circuit for a cathode ray tube (CRT).
BACKGROUND
Typically, the generation of an ultor or high voltage is accomplished in a flyback transformer which is included in a horizontal deflection circuit. Beam current variations cause modulations of the peak current in a primary winding of the flyback transformer and of the high voltage. Modulation of the primary winding current could produce undesired deflection current modulation. Disadvantageously, high voltage variations may alter the deflection sensitivity and result in raster size variations.
An East-West correction circuit is typically used for correcting outside pincushion distortion. U.S. Pat. No. 5,841,248, entitled, CHARGE CONTROLLED RASTER CORRECTION CIRCUIT in the name of Haferl, et al. (the Haferl, et al. patent) describes an East-West correction circuit that reduces the aforementioned effects of high voltage variations by using an isolating diode coupled between a primary winding of a flyback transformer and an East-West modulation transistor. The East-West modulation transistor is coupled in series with a horizontal output transistor and with the isolating diode.
In a deflection circuit requiring an inside pincushion distortion correction, a trace resonant circuit is, typically, included for modulating the deflection current. An example of an arrangement that includes a resonant circuit for providing inside pincushion distortion correction is shown in U.S. Pat. No. 5,115,171, entitled RASTER DISTORTION CORRECTION CIRCUIT, in the name of Haferl (the Haferl patent). It may be desirable to employ in a deflection circuit having an isolating diode such as described in, for example, the Haferl, et al. patent, a trace resonant circuit that provides inside pincushion distortion correction.
SUMMARY
A video display deflection apparatus, embodying an aspect of the invention, includes a deflection winding included in a first retrace resonant circuit, during retrace. A first switching arrangement is responsive to a first control signal at a frequency related to a first deflection frequency and coupled to a deflection winding and to a supply inductance for generating a deflection current in the deflection winding and a first retrace pulse voltage in the supply inductance. A second switching arrangement is responsive to a second control signal for applying the first retrace pulse voltage to a first inductance, during a controllable portion of retrace, to generate a modulation current in a first trace resonant circuit that includes the first inductance and an S-shaping capacitor. The modulation current varies at a frequency related to a second deflection frequency, in accordance with the second control signal, for providing inside pincushion raster distortion correction. A third switching arrangement is provided for conducting the modulation current in the first trace resonant circuit. A second inductance is coupled in a current path of each of the deflection and modulation currents for generating a current component of the modulation current that renders the third switching arrangement conductive, when trace begins.
REFERENCES:
patent: 4206388 (1980-06-01), Ishigaki et al.
patent: 4254365 (1981-03-01), Knight
patent: 4429257 (1984-01-01), Haferl
patent: 4634937 (1987-01-01), Haferl
patent: 4682085 (1987-07-01), Haferl et al.
patent: 4719392 (1988-01-01), Haferl
patent: 4780648 (1988-10-01), Haferl
patent: 4794307 (1988-12-01), Haferl
patent: 4890043 (1989-12-01), Davie
patent: 4906902 (1990-03-01), Haferl
patent: 4965496 (1990-10-01), Haferl
patent: 5115171 (1992-05-01), Haferl
patent: 5194784 (1993-03-01), Tripod
patent: 5323092 (1994-06-01), Helfrich et al.
patent: 5399945 (1995-03-01), Haferl et al.
patent: 5841248 (1998-11-01), Haferl et al.
Fried Harvey D.
Henig Sammy S.
Philogene Haissa
Thomson Licensing S.A.
Tripoli Joseph S.
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