| 摘要 |
<p>Device for exposing and separating photographic strip-material for the production of marginless copies having a roller-blind shutter comprising two shutter-curtains with accompanying shutter-rollers adapted to be driven by stepping motors. The strip-material is transported and positioned, along the path of travel of the said shutter-curtains, by a positioning roll also driven by a stepping motor. Stepping motors are controlled digitally by pulses from positioning devices. Prior to exposure of a section of strip by a projected picture, the strip-material is positioned in such a manner that its leading transverse edge is spaced by half a frame-length from the optical copying axis. In order to make an exposure, the said shutter-curtains are moved consecutively in the same direction, so that the closing edges thereof expose and then cover the said section of strip. The one edge of the exposed picture is formed by the transverse edge of the strip-material, while the opposing edge is masked by the shutter-curtain located on the other side of the optical copying axis. In the exposure-position, the closing edge of this shutter-curtain is spaced by half a framelength from the optical axis of the picture. The device may be adapted to different frame lengths by altering the programme of the positioning devices.</p> |
