Deflection and pincushion correction circuit

Claim 2

A pincushion correction circuit for use with a cathode ray tube display device comprising: a source of field deflection frequency signals, a source of line deflection frequency signals whose amplitude and polarity is modulated in accordance with said field deflection frequency signals, an amplifier having input and output terminals, means for applying said field deflection frequency signals and said line deflection frequency signals to said input terminal of said amplifier, a field deflection yoke coupled to said output terminal of said amplifier, and a transformer having primary and secondary windings, said primary winding being coupled in series with a capacitor to form a series resonant circuit tuned to the line deflection frequency, said series resonant circuit being connected in parallel with said yoke, and wherein said secondary winding of said transformer is coupled to said field deflection yoke in a manner such that said line deflection frequency signals are combined with said field deflection frequency signals to provide field deflection and top and bottom pincushion correction for said display device.

Claim 3

A circuit as defined in claim 1 wherein each of said line deflection frequency signals has a parabolic waveshape with an amplitude which is a maximum at the beginning and end of each field deflection interval, which diminishes toward the center of each field deflection interval and has a polarity which follows the polarity of said field deflection frequency signals.

Claim 4

A circuit as defined in claim 1 wherein said field deflection yoke comprises first and second winding portions and wherein said secondary winding of said transformer is serially coupled said field deflection yoke between said first and said second winding portions.

Claim 5

A circuit as defined in claim 1 wherein said amplifier circuit further comprises: negative feedback circuit means coupled to said field deflection yoke and said series resonant circuit and connected to said input terminal of said amplifier for feeding back to said input terminal a signal representative of said field deflection current and said line frequency current in said field deflection yoke and said line frequency current in said series resonant circuit, in a sense to preserve the waveshape of said line deflection signals which are applied to said input terminal from said source of line deflection signals.

Claim 6

A circuit as defined in claim 4 wherein a capacitor is coupled in circuit between said field deflection yoke and said negative feedback circuit means.

Claim 7

A top and bottom pincushion correction circuit for providing pincushion correction for a relatively wide angle deflection system for an image display device whereby top and bottom pincushion correction signals are simultaneously applied vertical deflection signals to a single vertical deflection output amplifier and wherein the relatively high frequency pincushion correction signals are injected into a vertical deflection yoke, the combination comprising: a source of vertical deflection sawtooth signals, a source of parabolic horizontal frequency pincushion correction signals whose amplitude and polarity is modulated in accordance with said vertical deflection sawtooth signals, an amplifier having input and output terminals, means for applying said vertical deflection signals and said pincushion correction signals to said input terminal of said amplifier, a vertical deflection yoke comprising first and second winding segments coupled between said output terminal of said amplifier and one terminal of a capacitor, the other terminal of said capacitor being coupled to a reference potential, and impedance matching means comprising a transformer having a primary winding which is coupled in series with a second capacitor to form a series resonant circuit tuned to the horizontal deflection frequency and coupled from said output terminal of said amplifier to said reference potential, said transformer further including a secondary winding serially coupled to said vertical deflection yoke between said first and second segments of said vertical yoke whereby vertical deflection current substantially flows through said vertical deflection yoke including the series coupled transformer secondary winding and whereby pincushion correction current is injected into said vertical deflection yoke by means of said transformer.

Claim 8

A top and bottom pincushion correction circuit for providing pincushion correction for a relatively wide angle deflection system for an image display device whereby top and bottom pincushion correction signals are simultaneously applied vertical deflection signals to a single vertical deflection output amplifier and wherein the relatively high frequency pincushion correction signals are injected into a vertical deflection yoke, the combination comprising: a source of vertical deflection sawtooth signals, a source of parabolic horizontal frequency pincushion correction signals whose amplitude and polarity is modulated in accordance with said vertical deflection sawtooth signals, an amplifier having input and output terminals, means for applying said vertical deflection signals and said pincushion correction signals to said input terminal of said amplifier, a vertical deflection yoke comprising first and second winding segments coupled between said output terminal of said amplifier and one terminal of a capacitor, the other terminal of said capacitor being coupled to a reference potential, and impedance matching means comprising a transformer having a primary winding which is coupled in series with a second capacitor to form a series resonant circuit tuned to the horizontal deflection frequency and coupled from said output terminal of said amplifier to said reference potential, said transformer further including a secondary winding serially coupled to said vertical deflection yoke between said first and second segments of said vertical yoke whereby vertical deflection current substantially flows through said vertical deflection yoke including the series coupled transformer secondary winding and whereby pincushion correction current is injected into said vertical deflection yoke by means of said transformer.

Claim 9

A top and bottom pincushion correction circuit for providing pincushion correction for a relatively wide angle deflection system for an image display device whEreby top and bottom pincushion correction signals are simultaneously applied with vertical deflection signals to a single vertical deflection output amplifier and wherein the relatively high frequency pincushion correction signals are injected into a vertical deflection yoke by means of an impedance matching device including a series resonant circuit, the combination comprising: a source of vertical deflection sawtooth signals, a source of parabolic horizontal frequency pincushion correction signals whose amplitude and polarity is modulated in accordance with said vertical deflection sawtooth signals, an amplifier having input and output terminals, said output terminal having a relatively low output impedance, means for applying said vertical deflection signals and said pincushion correction signals to said input terminal of said amplifier, a vertical deflection yoke coupled from said output terminal of said amplifier to a reference potential, said vertical deflection yoke providing a relatively high impedance to said pincushion correction information, and means for injecting said pincushion correction information into said vertical deflection yoke such that said pincushion correction signals produce a resulting correction current for providing the necessary pincushion correction.

Claim 10

A top and bottom pincushion correction circuit for providing pincushion correction for a relatively wide angle deflection system for an image display device whEreby top and bottom pincushion correction signals are simultaneously applied with vertical deflection signals to a single vertical deflection output amplifier and wherein the relatively high frequency pincushion correction signals are injected into a vertical deflection yoke by means of an impedance matching device including a series resonant circuit, the combination comprising: a source of vertical deflection sawtooth signals, a source of parabolic horizontal frequency pincushion correction signals whose amplitude and polarity is modulated in accordance with said vertical deflection sawtooth signals, an amplifier having input and output terminals, said output terminal having a relatively low output impedance, means for applying said vertical deflection signals and said pincushion correction signals to said input terminal of said amplifier, a vertical deflection yoke coupled from said output terminal of said amplifier to a reference potential, said vertical deflection yoke providing a relatively high impedance to said pincushion correction information, and means for injecting said pincushion correction information into said vertical deflection yoke such that said pincushion correction signals produce a resulting correction current for providing the necessary pincushion correction.

Claim 11

A circuit as defined in claim 7 wherein said means for injecting said pincushion correction information into said vertical deflection yoke comprises a transformer having primary and secondary windings, said primary winding being coupled in series with a capacitor to form a series resonant circuit tuned to the horizontal deflection frequency, said series resonant circuit being coupled between said output terminal of said amplifier and said reference potential, and wherein said secondary winding of said transformer is coupled to said vertical deflection yoke in a manner such that said pincushion correction signals are combined with said vertical deflection frequency signals to provide vertical deflection and top and bottom pincushion correction.

Claim 12

A circuit as defined in claim 8 wherein said vertical deflection yoke comprises first and second winding segments and wherein said secondary winding of said transformer is serially coupled to said vertical deflection yoke between said first and said second winding segments.

Claim 13

A circuit as defined in claim 7 wherein said amplifier further includes: sampling means coupled to said vertical deflection yoke and to said series resonant circuit for obtaining a signal representative of said vertical deflection current and said pincushion correction current in said vertical deflection yoke and said pincushion correction current in said series resonant circuit, and negative feedback circuit means coupling said sampling signal to said input terminal of said amplifier in a sense to preserve the parabolic waveshape of said pincushion correction signals which are applied to said input terminal of said amplifier from said source of pincushion correction signals.