Patent GB-1323378-A (GB)
Title: Two-dimensional positioning apparatus
IPC: G03B27/62
Filed: 1971-11-05
Abstract: 1323378 Positioning apparatus INTERNATIONAL BUSINESS MACHINES CORP 5 Nov 1971 [25 Nov 1970] 51532/71 Heading B4X [Also in Divisions G2 and G5] Two-dimensional positioning apparatus comprises a table 230 slidably mounted on a first frame 214 for movement in a first direction, the first frame being slidably mounted on a second frame 210 for movement in a second direction, e.g. at right angles to the first, drive means for driving the table and first frame in respective directions, first and second locking means for locking the table and first frame, and first and second frames together at selected positions and control means for controlling movement of the table and first frame to a selected position under the action of the drive means and then actuating the locking means to maintain the table in the selected position, a return mechanism serving to return the table to the home position. As shown the drive means comprises a motor 352, electromagnetic clutch, pulley 244, and cable 240 which passes around a pulley 242 mounted on the first frame 214 and is anchored on the table 230. Spring motors 216, 232 are connected by cables 218, 234 to the first frame and table respectively to bias them to a home position. Both the table 214 and first frame 230 have a plurality of discrete positions in which they can be looked, these positions being determined by the teeth of locking racks 220, 236 having co-operating solenoid-operated locking plungers. There are also provided for the table and first frame multisegment commutators 324, 358 with co-operating brushes 326, 360 the segments of the commutators corresponding in spacing to the locking positions of the racks 220, 358. The brushes and commutators form part of the supply circuit to the motor 352 and ensure supply of electricity thereto until a selected commutator segment is reached which is on open circuit the table and/or first frame then being in the desired position. The solenoids 322, 338 are also in circuit when the circuit through the respective commutator is closed and are of the type in which the plunger is retracted unlocking the table or first frame when the solenoid is energized. When the selected position is reached and the circuit is open the plungers automatically move forward again and locking is therefore effected automatically. Selection of the required position is by means of two sets of keys (not shown) corresponding to the segments of the commutator the keys being operable manually or under computer control. The apparatus is described particularly as applied to the enlargment and projection of selected frames of a microfiche transparency 256 mounted under a transparent cover 254 on a transparent support on the table 230, the selected frame for enlargment being moved to the viewing position 257. The apparatus may be operated under the control of a computer to provide visual information, e.g. at a travel station about fares, timetables, facilities, &c., the enquiring traveller being required to push a button indicating his answer to each of a series of questions displayed leading to the display of the desired information.