Abstract: A device for fixing a powder image on a receiving support using heat that consists of an image transfer roller internally provided with a first heating element having the same heat-generating power over the entire length of the image transfer roller, and a second heating element which has a higher heat-generating power in the edge zones of the image transfer roller than in the middle zone of the roller, and a pressure roller internally provided with a third heating element which like the second heating element has a higher heat-generating power in the edge zones than in the middle zone. The device may be in a warm-up condition in which the temperature of the rollers is not yet at the working level, stand-by condition in which the temperature is at the working level but in which no fixing is carried out, and a fixing condition in which fixing is carried out. During warm-up, all the heating elements generate the maximum power.