the film moves forwardly for leading and moves in the reverse direction for reverse leading during the reverse motion film is withdrawn from one of the loops while another loop is formed to take up the film this avoids the scratching and wear which otherwise would occur by repeatedly passing the film through the pinch rollers the film winding mechanism in the output cassette winds the film under tension but periodically relieves the tension in order to prevent the film from jamming in the output cassette application_number US 50322883 A description referring to fig1 an input film cassette 2 provided with a light seal 4 is removably secured to the frame 50 of the phototypesetter to support the film emerging from the cassette there is provided a plate 14 associated with a switch schematically shown at 6 for purposes to be explained later an input pinch rollers assembly 7 is provided that assembly includes a drive roller 10 a drive motor 12 and an idler roller 8 at the output of the input rollers assembly the film is supported by a block 16 having an edge co operating with a rotary cutter 18 driven by a motor or solenoid 20 the film is further supported by a plate 22 the upper surfaces of plates or guides 14 16 and 22 are aligned in a plane represented by line x x 39 which is tangent to the drum 24 the drum 24.