| 摘要 |
PURPOSE:To make the pressure fixing device small and light by reducing contact pressure when not using by using a spring of shape memory alloy that pressure contacts a roller and obtaining specified pressure only when fixing operation. CONSTITUTION:A rod 6 is wound with a coil spring 7 made of shape memory alloy and a habit is given to maintain shrinked shape at normal temperature, and elongates on heating. A heater 9 is placed near the rod 6 and coil spring 7 and the heater is energized only when the fixing device is used. When starting picture forming operation, the heater 9 is energized, and the coil spring 7 is heated and elongated. Pressure fixing is performed by raising the pressure of a pair of rollers 1, 2 to specified pressure before arrival of transferring agent at the fixing position. On completion of fixing, the heater is weakened and the coil spring 7 is cooled and shrinked. Thus, pressing force between rollers can be diminished to the weight of rollers and accessory members. By this way, the whole fixing device can be made light and compact. |
