High voltage protection circuit

Claim 2

High voltage protection apparatus for a display system comprising: a high voltage transformer responsive to a first alternating voltage for providing a high voltage accelerating potential for beam current; a first winding coupled to said high voltage transformer for providing a second alternating voltage representative of said high voltage accelerating potential; a protection circuit coupled to said first winding and responsive to said second alternating voltage for providing a disabling signal for disabling normal operation of said display system when said high voltage accelerating potential exceeds first predetermined values; beam current sensing means responsive to said beam current for providing at a first terminal a first voltage representative of the magnitude of said beam current; and first means coupled to said first terminal and said first winding for clamping a winding terminal of said first winding to said first voltage during at least a portion of an interval of said second alternating voltage when said beam current equals or goes beyond a predetermined amount for changing the magnitudes of said first predetermined values.

Claim 3

A circuit according to claim 1 wherein said first means comprises a diode poled to conduct when said beam current equals or goes beyond said predetermined amount.

Claim 4

A circuit according to claim 1 wherein said beam current sensing means comprises a voltage divider through which said beam current flows, said first means coupled to a junction of said voltage divider.

Claim 5

A circuit according to claim 1 including a deflection circuit coupled to said high voltage transformer.

Claim 6

A circuit according to claim 4 wherein said first means loads said winding terminal during at least a portion of each deflection cycle for changing the magnitudes of said first predetermined values.

Claim 7

A circuit according to claim 5 wherein said high voltage transformer includes a tertiary winding magnetically coupled to a primary winding of said high voltage transformer.

Claim 8

A circuit according to claim 5 wherein said high voltage transformer is coupled to a high voltage tripler for providing said high voltage accelerating potential at an output terminal of said high voltage tripler.

Claim 9

A circuit according to claim 7 wherein said beam current sensing means is coupled to a DC beam current input terminal of said high voltage tripler.

Claim 10

A circuit according to claim 8 wherein said beam current sensing means comprises a voltage divider through which said beam current flows, said first means coupled to a junction of said voltage divider.

Claim 11

A circuit according to claim 1 wherein said protection circuit includes: second means coupled to said first winding for detecting a peak excursion of said second alternating voltage; a comparator coupled to an output terminal of said second means and to a source of reference voltage for providing said disabling signal; and means for coupling said disabling signal to said deflection circuit for disabling normal operation of said display system.

Claim 12

A high voltage protection system for a television receiver comprising: a deflection winding; a deflection circuit coupled to said deflection winding for providing scanning current to said deflection winding; high voltage means including an output transformer coupled to said deflection circuit for providing a high voltage accelerating potential for beam current; a secondary winding coupled to said output transformer for providing a first signal representative of said high voltage accelerating potential at a first terminal; beam current sensing means responsive to said beam current for providing a beam current signal representative of said beam current; a protection circuit responsive to said first signal for providing a disabling signal for disabling normal operation of said television receiver when said high voltage accelerating potential exceeds first predetermined values; and first means coupled to said secondary winding and responsive to said beam current signal for loading said first terminal during at least a portion of each deflection cycle when said beam current decreases to less than a second predetermined value for changing the magnitudes of said first predetermined values.

Claim 13

A high voltage protection system for a television receiver comprising: a deflection winding; a deflection circuit coupled to said deflection winding for providing scanning current to said deflection winding; high voltage means including an output transformer coupled to said deflection circuit for providing a high voltage accelerating potential for beam current; a secondary winding coupled to said output transformer for providing a first signal representative of said high voltage accelerating potential at a first terminal; beam current sensing means responsive to said beam current for providing a beam current signal representative of said beam current; a protection circuit responsive to said first signal for providing a disabling signal for disabling normal operation of said television receiver when said high voltage accelerating potential exceeds first predetermined values; and first means coupled to said secondary winding and responsive to said beam current signal for loading said first terminal during at least a portion of each deflection cycle when said beam current decreases to less than a second predetermined value for changing the magnitudes of said first predetermined values.