Patent GB-960431-A (GB)
Title: Improvements in or relating to holders for photographic negatives and the like
IPC: G03F7/22
Filed: 1959-09-25
Abstract: 960,431. Photographic negative holders. PICTORIAL MACHINERY Ltd., C. BRAGG, and B. S. PENNELS. Aug. 16, 1960 [Sept. 25, 1959], No. 32719/59. Heading G2A. A holder for a photographic plate or negative comprises an outer frame,within which is supported an inner frame carrying the plate, the inner frame being adjustable relative to the outer frame in a direction perpendicular to its plane, and the two frames being connected by an airtight flexible diaphragm. The preferred form of holder shown in Fig. 1 has a metal outer frame 11 surrounding a metal inner frame 12, the two being connected by a membrane 13 of rubber or like material clamped and screwed to the respective frames. Frame 12 carries a sealing flange 16 which receives the negative plate or transparency 17. Frame 11 carries a sealing flange 18, and four corner brackets 19 having threaded therein adjusting screws 22 which engage the inner frame 12. Thus these adjusting screws control movement of the inner frame relative to the outer, and perpendicular to the plane thereof; the movement is adjusted so as to bring the front face 23 of the plate 17 and the front face 24 of flange 18 into coplanar relationship. Plate 17 is then clamped edgewise between three pads 25 and three further adjustable clamping pads 27 controlled by screws 28. A conduit 29 is provided for evacuating the space between faces 23, 24 and the photosensitive surface with which they are brought into contact during the printing operation. Each side of the outer frame has three locating surfaces 31, 32, 33 provided by the end faces of adjustment screws. Surfaces 31, 32 are on the ends of screws 34, which thread into frame 11 and can be locked in adjusted position by screws 35. Surfaces 33 are on the ends of screws 36, each of which threads into one limb of a bridgepiece 37 fixed to frame 11. Screws 36 can be locked by nuts 41. The holder is first placed on a register device (Figs. 3 and 5) having accurately inscribed vertical and horizontal datum lines 203, 204 on a glass plate 202 illuminated from behind. A rigid bar 42 at the lower part of the register device carries two locating plates 43 whose upper faces 46 are parallel to the horizontal datum lines 204. When the holder is located on the register device, one pair of locating surfaces 31, 32 rest on the faces 46. The holder, and hence the plate 17, can be brought into a desired orientation with respect to the horizontal datum lines 204 by adjustment of screws 34, which are then locked. The bar 42 also carries a block 47 having a vertical locating face 51 which enters between the arms of the bridge-piece 37 and abuts against the locating surface 33. Adjustment of screw 36 moves the holder relative to the vertical datum line 203, and is locked when the desired orientation is reached. The holder and plate is now transferred to a step- and-repeat photo-composing machine. Fig. 7 shows a unit which is secured to the slide 210 of the saddle of the traversing bar 211 of the said machine. A slide 63 of the unit co-operates with the slide of the saddle, and can be locked in position by a screw 66. Slide 63 has two horizontal locating faces 68, 69 on which rest the locating surfaces 31, 32 of the plate holder. A table 67 forming part of slide 63 also carries a vertical locating surface against which the locating face 33 is caused to abut. The holder is now correctly orientated with respect to the photo-composing machine, and is clamped in position. The underside of the table 67 carries a rack 88 engaging a pinion on the saddle, which pinion is rotated by a handle 90 to carry the unit and holder towards a photo-sensitive printing surface until the negative plate is in contact with said surface, and the printing operation effected. The saddle is movable along the traversing bar 211 by known means. Since locating screws 34, 36 are provided on each of the four sides of frame 11, the holder can be accurately registered and located any way round. The holder may also be used to superimpose accurately the prints made from two or more colour-separation negatives.