Parabolic voltage generating apparatus for television
AssigneeRCA Corporation
InventorsWalter Truskalo, Thomas F. Nolan
Life of this patent
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Abstract
A dynamic focus voltage generating circuit for television generates a parabolic voltage at the horizontal rate that is responsive to a synchronizing signal. The parabolic voltage is generated from a sawtooth waveform having an upramping portion, a downramping portion and a flat portion such that only the length of the flat portion of the sawtooth waveform varies when the frequency of the synchronizing signal changes.
Claims11
A video apparatus responsive to a periodic synchronizing signal at a frequency that is related to a deflection frequency for generating a parabolic first signal synchronized to said synchronizing signal, comprising:
- means responsive to said synchronizing signal for generating a sawtooth waveform having, during a given period of said sawtooth waveform, an upramping portion, a downramping portion and a substantially flat portion;
- means responsive to said synchronizing signal and coupled to said sawtooth waveform generating means for varying the length of said flat portion when a change occurs in the length of the period of said synchronizing signal without affecting the length of each of said downramping and upramping portions such that the length of said given period of said sawtooth waveform is determined in accordance with the length of the period of said synchronizing signal and such that said sawtooth waveform becomes synchronized to said synchronizing signal;
- and
- means responsive to said sawtooth waveform for generating from said upramping and downramping portions corresponding portions of said parabolic first signal.
Dependencies are inferred from the claim text.