Patent ID: 6563496
Filing Date: 2003-05-13
Classification: H04N

Abstract:
A cut-off adjusting apparatus for adjusting a cut-off of a cathode ray tube display receiving an input video signal, comprising:video signal processing means for adjusting at least a contrast based on a first control signal, and for adjusting a pedestal level of a video signal to a black level irrespective of the input video signal and producing an output signal at an output terminal; a clamp capacitor having a first electrode connected to the output terminal of said video signal processing means and a second electrode connected to a cathode of said cathode ray tube; a rectifying element connected so that a forward direction thereof is set from a connection point between said second electrode of said clamp capacitor and said cathode toward a reference potential; cut-off control means for adjusting an amount of current discharging from said clamp capacitor to the reference potential in accordance with a second control signal so as to maintain a cathode voltage at a predetermined voltage; and current measuring means for outputting the first control signal to said video signal processing means so as to output a black level signal when receiving an enforced adjustment instruction and for measuring a current flowing from said clamp capacitor through said rectifying element to the reference potential as a cathode current at a time of the black level signal.