| 摘要 |
PURPOSE:To detect the perforations of a film under traveling by projecting a strip- like visible ray at an angle of projection close to 90 deg. along the width direction on one side of a film, detecting the reflected ray thereof at an angle of detection close to 90 deg., and measuring the quantity of the detected light. CONSTITUTION:A plastic material is melted and kneaded by an extruder 1, is extruded in a film shape onto a cooling drum 3 through a mouthpiece 2, and is cooled to solidify. A film F is stretched in its longitudinal direction between low speed rolls 41 and ghigh speed rolls 42, and enters a tenter 5. Here, the film F is chucked by clips 6 at both side edges and is stretched broadside. The film F out from the tenter 5 is taken up into a roll shape by a take-up machine 7. To detect the perforations at this time, a visible ray from a light projector 8 is reflected by the film F under traveling, and the reflected light thereof is detected and measured with a camera (photodetector) 9. |
