Patent ID: 6118233
Filing Date: 2000-09-12
Classification: H04N

Abstract:
A video imaging apparatus, comprising:a cathode-ray tube including a focus electrode;a source of a focus voltage correction input signal;an amplifier having a first input responsive to said focus voltage correction input signal for generating at an output of said amplifier a dynamic focus voltage component of a focus voltage that is coupled to said focus electrode;a first semiconductor switch responsive to a first periodic control signal and coupled to a signal path of said focus voltage correction input signal for disabling said dynamic focus voltage component, during an automatic kine bias measurement interval of a deflection cycle; anda second semiconductor switch responsive to a second periodic control signal and coupled to said amplifier for applying a second input signal to a second input of said amplifier to control said focus voltage, during said automatic kine bias measurement interval, such that, outside said automatic kine bias measurement interval, said second input signal is decoupled from said amplifier.