| 摘要 |
<p>1415314 Tomography CFC PRODUCTS Inc 8 Nov 1972 [26 Nov 1971] 51557/72 Heading H5R In a method of dynamic tomography successively exposed films 20, 30, 40 are stacked on top of one another in a viewer 50 and successive planes of interest are brought into focus by relatively displacing the films in the directions of guides 52, 54 by cams 58, 60 acting on edges of the film resulting from the cutting of rectangular films into parallelograms with an appropriate angularity, and the invention is concerned with a cutter for readily obtaining the correct shape of film. The cutter, Fig. 6, comprises a film support table 64 having a fiduciary line 66 thereon, this being aligned with indicia A, B on the film produced by two lead balls aligned with the direction of movement during tomography, and cutting edges 70, 72 for cutting the film along lines 74, 76 parallel to line 66. To cut the other sides of the parallelogram, carriers 78, 82 are slidably mounted on ways 80, 84 and are pivotally linked by a cutting guide 86. A pointer 96 on carrier 82 is aligned with a reference mark C produced during exposure by a, lead ball not in the same plane as those providing indicia A and B and therefore the position of C relative to A and B is indicative of the exposure angle. A pointer 94 on carrier 78 is aligned with point A and the cutting guide 86 will then lie along the correct cutting line 102 and a similar cutting guide (not shown) is arranged to lie along the line 104, thus enabling the parallelogram to be correctly formed. A detailed description of a practical machine based on the principle shown in Fig. 6 is described with reference to Figs. 7 to 24 (not shown) including the mounting of the cutters, the provision of vacuum platens for holding the film in position, an arrangement for moving the film support between two planes for cutting each opposite pair of sides to avoid intersecting cutting edges at the corners and an automatic arrangement of microswitches and vacuum control valves for moving, securing and cutting a film in a pre-set sequence.</p> |
