A device for displaying an analog signal on a display screen (7) which is scanned by means of a line deflection generator (21) and a frame deflection generator (23). The device comprises a signal processing device (13) forforming a processed signal by repeating the analog signal at the line deflection frequency, a reference voltage generator (19) for generating a reference voltage which is dependent on the frame deflection voltage, and a comparator (17) for comparing the reference voltage and the processed signal and for generating a control signal which causes a brightening of the scanned display screen (7) when both signals are approximately equal. In order to improve the picture quality, the device comprises means (18) for adding a varying auxiliary signal to the processed signal. The frequency of this auxiliary signal amounts to at least ten times the line deflection frequency.