Abstract A circuit for obtaining a focus voltage that varies with the final anode voltage has a rectifier, a resistor, and a capacitor connected to a horizontal output transformer, which is specially designed to be resonant at the fifth harmonic. The series arrangement of the diode and the capacitor is connected between primary and secondary windings of the transformer, namely the anode of the diode is connected to a tap on the primary, and the remaining end of the capacitor is connected to that end of the secondary winding to which a capacitor for the fifth harmonic tuning is connected. The other capacitor end is connected to a tap on the primary. The latter tap comprises a much smaller number of turns than the first-mentioned tap to which the anode of he diode is connected. The required focusing voltage is derived from the resistor which is arranged between the cathode of the diode and ground.
A circuit for operation from a voltage source comprising an induction coil; switching means coupled to said coil and said source for discontinuously applying the voltage from said source through said coil; a television deflection coil coupled to said induction coil; a transformer having a primary coupled between said switching means and said induction coil, and a secondary for supplying display tube high voltage; a winding closely coupled to said secondary and having first and second ends, said first end being coupled to said primary; an first capacitor coupled between said winding second end and said primary; a rectifier having one end coupled to said primary, and a second end; a resistor means for supplying a focusing voltage having a first end coupled to said rectifier second end, and a second end coupled to ground; a second capacitor having a first end coupled to said rectifier second end, and a second end coupled to the junction of said first capacitor and said winding.
Claim 2
Dependent Claim
163 words
A circuit for operation from a voltage source comprising an induction coil; switching means coupled to said coil and said source for discontinuously applying the voltage from said source through said coil; a television deflection coil coupled to said induction coil; a transformer having a primary coupled between said switching means and said induction coil, and a secondary for supplying display tube high voltage; a winding closely coupled to said secondary and having first and second ends, said first end being coupled to said primary; an first capacitor coupled between said winding second end and said primary; a rectifier having one end coupled to said primary, and a second end; a resistor means for supplying a focusing voltage having a first end coupled to said rectifier second end, and a second end coupled to ground; a second capacitor having a first end coupled to said rectifier second end, and a second end coupled to the junction of said first capacitor and said winding.
Claim 3
Dependent Claim
19 words
A circuit as claimed in claim 1 wherein said winding and said secondary comprise portions of the same coil.
Claim 4
Dependent Claim
19 words
A circuit as claimed in claim 1 wherein said resistor and second capacitor have a substantially large time constant.
Claim 5
Dependent Claim
20 words
A circuit as claimed in claim 1 wherein said induction coil and said primary comprise portions of the same coil.
Claim 6
Dependent Claim
16 words
A circuit as claimed in claim 1 wherein said switching means comprises a horizontal output tube.
Claim 7
Dependent Claim
18 words
A circuit as claimed in claim 1 further comprising an inductor coupled in parallel with said first capacitor.