PURPOSE: To adjust the aberration of convergence by small memory capacity by providing two RAMs which stores correction data corresponding to two adjustment points in a vertical direction and a scanning line between them and using two RAMs to write and read alternately.
CONSTITUTION: A CPU 2 counts correction amount every scanning line between adjustment points of the first line and the second line and stores it with the correction data of the adjustment point of the first line in the area (a) of a RAM 4. The data stored in the area (a) is read synchronizing with the synchro nizing signal of a television receiver, converted to analog amount in the respec tive colors of D/A converters 5∼8, smoothed in horizontal direction in L.P.Fs 9∼12 and supplied to the respective colors of convergence yokes after amplifica tion in amplifiers 13∼16. While the correction data is read out from the area (a) of the RAM 4, the correction amount between the adjustment points of the second line and the third line is counted and stored in the area (b) of the RAM 4. By using the areas (a) and (b) to write and read alternately, a same interpolating operation as usual can be executed in the memory capacity which is 1/4 of a usual memory.