Circuit and method of linearity correction for CRT deflection circuits
AssigneeData General Corporation
InventorsGerald Manktelow, Kenneth T. Wolff
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Abstract
Electronic apparatus and method is disclosed for generating a linearity correction signal for use in or with a CRT electron beam deflection circuit. In a preferred embodiment, transistor is used to vary the parameters of a multiple feedback infinite gain bandpass filter such that the filter is essentially on the point of oscillation during trace, but is highly damped during retrace.
Claims10
Electrical apparatus for generating a deflection signal for the electron beam in a raster scan CRT, said apparatus comprising:
- active bandpass filter means for generating a first deflection signal waveform;
- means for generating a second deflection signal waveform;
- and
- means for alternating between said filter and said second waveform means, such that said filter generates the deflection signals for said electron beam during scan and said second waveform means generates the deflection signals for said electron beam during retrace.
A method for generating a deflection signal for the electron beam in a raster scan CRT using a deflection circuit, said method comprising the steps of:
- (a) supplying a voltage to an active bandpass filter during retrace such that the output of said filter is a substantially straight line;
- (b) removing said voltage from said filter at the end of retrace such that the output of said filter is substantially sinusoidal during scan;
- and
- (c) repeating steps (a) and (b) for each scan cycle.
Electrical apparatus for generating a deflection signal for the electron beam in a raster scan CRT, said apparatus comprising:
- an active bandpass filter;
- a voltage source;
- and
- means connected to said voltage source for supplying the voltage from said voltage source to said filter during retrace and removing said voltage from said filter during scan whereby the parameters of said filter are varied.
Electrical apparatus for generating an electron beam deflection signal in a raster scan CRT, said apparatus comprising:
- means for generating a substantially sinusoidal deflection signal waveform;
- and
- means for damping the output of said waveform generating means during retrace such that the output of said apparatus during retrace is a substantially straight line.
Dependencies are inferred from the claim text.