Patent ID: 6285143
Filing Date: 2001-09-04
Classification: G09G,H04N

Abstract:
Apparatus for applying beam cut-off bias to the grid of a kinescope, comprising:a capacitor having first and second electrodes;a source for providing a beam cut-off control signal;a first switching circuit responsive to a first condition of said control signal for allowing a first, charging current to be supplied to said first electrode of said capacitor from a first voltage source when beam cut-off is not desired, and responsive to a second condition of said control signal for coupling said first electrode of said capacitor to a source of reference potential when beam cut-off is desired;a second switching circuit having a first electrode coupled to a second voltage source, a second electrode coupled to said second electrode of said capacitor and to said grid of said kinescope for coupling a second voltage source to said second electrode when enabled and isolating said second electrode from said second voltage source when disabled, and a third electrode; anda third switching circuit for allowing a second current that is independent of said first current to flow through a second circuit path to said second switching circuit to enable said second switching circuit when beam cut-off is not desired and for disabling said second switching circuit when beam cut-off is desired,said second circuit path including first and second resistors connected in series between said source of said first voltage source and said third electrode of said second switching circuit,said third switching circuit being coupled between said first switching circuit and a connection point between said first and second resistors.