Combined dynamic focus circuit flyback capacitor

Claim 2

In a CRT display system utilizing a semiconductor switch in the fast scan axis output stage of a flyback beam deflection circuit, the improvement comprising a resonant circuit coupled to said flyback circuit for production of a dynamic focus voltage waveform and for providing the only flyback capacitance of the circuit.

Claim 3

In the CRT display system of claim 1, wherein said resonant circuit comprises a parallel resonant tank circuit including a first inductor and a first capacitor.

Claim 4

In the CRT display system of claim 2, wherein said resonant circuit is capacitively coupled to said flyback circuit by a second capacitor.

Claim 5

In the CRT display system of claim 3, wherein a node, to which is connected a terminal of each of said first and second capacitors and said inductor, is capacitively coupled to a cathode ray tube focus grid by a third capacitor.

Claim 6

In the CRT display system of claim 4, wherein said flyback beam deflection circuit includes a deflection yoke and the flyback capacitance Ceq of said resonant circuit coupled to said flyback circuit is: ##EQU7## where: L1=inductance of said first inductor; Ly=inductance of said deflection yoke; C1=capacitance of said first capacitor; C2=capacitance of said second capacitor.

Claim 7

A cathode ray tube beam deflection circuit comprising: a deflection yoke having a first terminal connected to a first source of first potential; a semiconductor switch connected between a second terminal of said yoke and a second potential; a diode connected between said second terminal and said second potential and reverse biased with respect to the direction of positive current flow through said semiconductor switch; a parallel resonant circuit including a first capacitor and a first inductor, said parallel resonant circuit being capacitively coupled through a second capacitor across said diode, wherein said capacitively coupled resonant circuit provides a dynamic focus voltage waveform and the only flyback capacitance in the circuit.

Claim 8

A cathode ray tube beam deflection circuit comprising: a deflection yoke having a first terminal connected to a first source of first potential; a semiconductor switch connected between a second terminal of said yoke and a second potential; a diode connected between said second terminal and said second potential and reverse biased with respect to the direction of positive current flow through said semiconductor switch; a parallel resonant circuit including a first capacitor and a first inductor, said parallel resonant circuit being capacitively coupled through a second capacitor across said diode, wherein said capacitively coupled resonant circuit provides a dynamic focus voltage waveform and the only flyback capacitance in the circuit.

Claim 9

The cathode ray tube beam deflection circuit of claim 6 wherein a node, to which is connected one terminal each of said first and second capacitors and said first inductor, is coupled through a third capacitor to a cathode ray tube focus grid.

Claim 10

The cathode ray tube beam deflection circuit of claim 7 wherein said flygack capacitance is: ##EQU8## where: Ceq=effective flyback capacitance; L1=inductance of said first inductor; Ly=inductance of said deflection yoke; C1=capacitance of said first capacitor; C2=capacitance of said second capacitor.