Patent ID: 7372509
Filing Date: 2008-05-13
Classification: H04N

Abstract:
1. A dynamic focus amplifier for generating a focus voltage for a focus electrode of a cathode ray tube, comprising: a source of a high voltage; a pull-up transistor responsive to a control voltage and coupled to said source of said high voltage and to a capacitive load for generating a first dynamic focus voltage portion of said focus voltage in said capacitive load; a source of a periodic dynamic focus input signal at a frequency related to a deflection frequency; and a pull-down transistor responsive to said input signal and coupled to said capacitive load to amplify said input signal for generating a second dynamic focus voltage portion of said focus voltage in said capacitive load, said capacitive load being coupled to said pull-up transistor for generating said control voltage of said pull-up transistor from a charge stored in said capacitive load.