Convergence correction apparatus

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.