Patent GB-995219-A (GB)
Title: Micro-image storage and retrieval apparatus
IPC: G03B21/11
Filed: 1964-01-09
Abstract: 995, 219. Optical and photographic apparatus. NATIONAL CASH REGISTER CO. Jan. 9, 1964, [Feb. 8, 1963], No. 1036/64. Headings G2A and G2J. In order to provide access to micro-images of documents arranged in concentric circular tracks on a transparent disc, separate coarse and fine disc adjustment mechanisms are provided to locate a selected image on the common optical axis of, and between, a taking objective and a viewing objective. As shown, the disc 30 is of transparent flexible plastic coated with either a photographic silver halide emulsion or with a phototropic layer. The latter layer is exposed to U.V. light to produce an image without any processing and to yellow light to erase the image. After adjustment, the image on the disc is brought into the commonimage plane of taking objective 36 and projection objective 48 by clamping the disc 30 against locating abutment 281. This is effected, on energizing solenoid 285, by means of linkage 290, 297 which slides objective 36 to the left. A projection optical system is described (Fig 7, not shown) and includes a magnetic focusing arrangement. Each image position on disc 30 is identified by a group of five lights, each digit relating to one switch on one of five key-boards. The three key boards 170, 171 and 203, Figs 8 and 9, provide the coarse and fine angular adjustments of the disc about its central axis of rotation 28. As the disc is turned from a zero datum position sliding contacts 174 and 175 move from their zero positions, the former at the same angular speed as shaft 28 and the latter at five times this speed. Each segment of stationary commutation 172 is connected to two switches of keyboard 170 one of which completes a circuit through solenoid 158 and the other of which bye-passes this solenoid. Accordingly, either odd number or even number circular tracks of micro-images are brought out of the scope of the subsequent radial adjustment of the disc. The passage of sliding contact 175 over each segment of stationary commutator 173 coincides with the passage of each too the 81 on index wheel 80 past pawl 82 and, when the circuit is completed through a closed switch of key-board 171, solenoid 85 is energised to engage pawl 82 with the selected tooth 81. The momentum of wheel 80 carries slide bar 91, Fig. 2, to its extreme left hand position, and this brings sliding contacts 204 and 205 to the zero and of the rows of stationary contacts 104 and 103 (Fig. 9). During the return of slide bar 91 to the right under the action of tension spring 109, each passage of a sliding contact 204 or 205, Fig. 9 over a stationary contact coincides with the passage of a tooth of a rack 101 or 100 beneath a pawl 117 or 118. When the circuit is completed through a closed switch of keyboard 203, either solenoid 115 or 116 is energized to bring the either pawl 117 or 118 into engagement with the appropriate rack tooth and slide bar 91 to rest. This completes the fine angular adjustment of disc 30. As soon as shaft 28 is braked by pawl 82, the radial adjusting mechanisms are set in operation and arm 26 begins to swing the disc 30 and shaft 28 about its pivot 23. The drive for turning disc 30 is imparted without interruption to pinion 64 meshing with rack 61 to impart downward movement to the disc and a contact making member. This movement is tracked, as before, over a row of stationary contacts and the next position is identified by a closed switch on a key-board. A fine radial adjustment to select the individual circular track in which the required micro-image line is effected by means of a further key-board controlling tracking and pawl operating mechanisms similar to those described above.