FILM DRIVING MECHANISM

PURPOSE:To make the feed speed of a film constant even if the thickness of the film varies and to stabilize the contactness with rollers by moving up and down a contact roller to and away from two small-sized rollers at fixed positions and clamping the film between them. CONSTITUTION:A touch roller 103 and a drive roller 104 have their center positions fixed and the film 1 is loaded in the gap between the rollers 103 and 104 which is formed by moving back the contact roller 101; and the roller 103 is moved forth to press the film, the roller 104 is driven and an image is focused 4 on the film surface through a lens 3 to expose the film. The diameter of the roller 101 is much larger than the diameter of the small rollers, so even if the loaded film varies in thickness, the focus 4 has almost no shift in position. Therefore, even when the film thickness varies, no defocusing occurs and the radius R of curvature does not vary, so the film feed speed is constant and the contact with the roller can be stabilized.