Deflection system with overscan protection
AssigneeRCA Corporation
InventorJohn Charles Peer
Life of this patent
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Abstract
In a deflection system including an oscillator and an amplifier providing scanning current for a deflection winding, a parabolic voltage developed at the deflection winding is superimposed on the oscillator direct current operating voltage in such a proportion that an increased parabolic voltage level, indicative of excessive scanning current from either an overscan or low operating frequency condition, causes the oscillator to operate at a higher frequency which decreases the deflection winding current and therefore the parabolic voltage and thereby permits the use of less expensive circuit components having lower maximum voltage level ratings.
Claims5
A deflection system overscan protection circuit, comprising:
- an oscillator for producing a generally sawtooth waveform;
- a deflection winding;
- an amplifier coupled to said oscillator and said deflection winding and responsive to said sawtooth waveform for providing a generally sawtooth scanning current to said deflection winding;
- means for obtaining a parabolic voltage waveform from said deflection winding, which parabolic voltage waveform is proportional to the amount of scanning current through said deflection winding, and for coupling said parabolic voltage to said oscillator for superimposing said parabolic voltage on a direct current operating voltage of said oscillator such that a change in said parabolic voltage causes said oscillator to change its frequency, thereby changing the peak amplitude of said scanning current.
Dependencies are inferred from the claim text.