PURPOSE: To make it possible to adjust convergences at four corners independently by providing a horizontal saw-tooth wave generation circuit, a vertical saw-tooth wave generation circuit, a modulator circuit, a square wave generation circuit, a separator circuit and a convergence yoke.

CONSTITUTION: When pulses synchronized with horizontal and vertical scanning are supplied to input terminals 14 and 15 respectively, horizontal and vertical saw-tooth waves generated by saw- tooth wave generation circuits 16 and 17 are supplied to modulator circuit 18. The vertical saw-tooth wave is inputted to square wave generation circuit 19 to generate square waves different from each other in phase by 180°. In circuit 18, the horizontal saw-tooth wave is modulated with the vertcical saw-tooth wave, and the output is supplied to separator circuit 20. In circuit 20, the input is separated into four parts, namely, horizontal scanning latter halves in the vertical scanning first half and the latter half (the upper part and the lower part of the screen right) and horizontal scanning first halves in the vertical scanning latter half and the first half (the upper part and the lower part of the screen left) by the square wave from circuit 19, and the output is amplified by 25 through variable resistances 21∼24 and is supplied to convergence yoke 26. As a result, convergences at four corners can be adjusted independently, and the adjustment work becomes easy.