Convergence correction apparatus

Claim 2

A convergence correction apparatus comprising: scanning waveform generating means for generating a scanning waveform with receipt of a sync signal for scanning an electron beam in a cathode ray tube; control means, which receives the scanning waveform and a control signal, for controlling a raster size in response to the scanning waveform; and correction waveform generating means, which receives the scanning waveform and the control signal, for generating a correction waveform in response to the scanning waveform and the control signal, wherein said correction waveform generating means further includes a feedback control means to generate the correction waveform having a sawtooth waveform component and a parabola waveform component where the sawtooth waveform component is proportional to a change in amplitude of the control signal and the parabola waveform component is proportional to the square of the chance in amplitude of the control signal.

Claim 3

The convergence correction apparatus as claimed in claim 1, wherein said correction waveform generation means generates a divisional correction waveform by detecting a scanning center position according to the sawtooth waveform.

Claim 4

A convergence correction apparatus comprising: scanning waveform generating means for generating a scanning waveform with receipt of a sync signal for scanning an electron beam in a cathode ray tube; control means for controlling the amplitude of the scanning waveform generated by said scanning waveform generating means thereby to control the raster size with receipt of a control signal; fundamental correction waveform generating means for receiving the scanning waveform and the control signal and for generating a fundamental correction waveform for correcting the convergence in response to the scanning waveform and the control signal; memory means for storing amplitude control data for controlling the amplitude of the fundamental correction waveform generated by said fundamental correction waveform generating means; multiplication type digital-to-analog conversion means for effecting a multiplication type digital-to-analog conversion of the fundamental correction waveform with the amplitude control data supplied from said memory means; and correction waveform generating means for generating a correction waveform for correcting the convergence according to the digital-to-analog converted signal output by said multiplication type digital-to-analog conversion means.

Claim 5

A convergence correction apparatus comprising: scanning waveform generating means for generating a scanning waveform with receipt of a sync signal for scanning an electron beam in a cathode ray tube; control means for controlling the amplitude of the scanning waveform generated by said scanning waveform generating means thereby to control the raster size with receipt of a control signal; fundamental correction waveform generating means for receiving the scanning waveform and the control signal and for generating a fundamental correction waveform for correcting the convergence in response to the scanning waveform and the control signal; memory means for storing amplitude control data for controlling the amplitude of the fundamental correction waveform generated by said fundamental correction waveform generating means; multiplication type digital-to-analog conversion means for effecting a multiplication type digital-to-analog conversion of the fundamental correction waveform with the amplitude control data supplied from said memory means; and correction waveform generating means for generating a correction waveform for correcting the convergence according to the digital-to-analog converted signal output by said multiplication type digital-to-analog conversion means.