Quality of images formed electrophotographically on a photoreceptor is improved by controllingly switching on and off a heater for the photoreceptor such that the photoreceptor temperature remains higher than the measured ambient temperature by several DEG C. to 20 DEG plus several DEG C. At the same time, the output of the charger for the photoreceptor or brightness of an image forming lamp is controlled according to the measured surface temperature of the photoreceptor.
