Patent GB-1017131-A (GB)
Title: Improvements in or relating to disc information files
IPC: G11B5/55
Filed: 1961-09-06
Abstract: 1,017,131. Magnetic recording &c. apparatus; selective signalling. J. HANDLEY. Sept. 6, 1962 [Sept. 6, 1961; Sept. 26, 1961; Nov. 7, 1961; Dec. 5, 1961; Feb. 16, 1962; May 23, 1962], Nos. 31938/61, 34411/61, 39744/61, 43399/61, 6040/62 and 19921/62. Headings G4H and G5R. [Also in Division F2] A rotary disc information file comprises at least one record disc mounted on a rotatable disc shaft, a read-arm individual to the or each disc storage surface and movable to select any one of a number of coaxial circular information storage tracks, and read-arm operating means comprising a continuously rotating drive shaft, a driven element rotatably mounted on the drive shaft between an electricallyoperable clutch and an electrically-operable brake, and change-over control means for switching an electrical power supply between clutch and brake. The apparatus may comprise a number of magnetic discs mounted in groups of eight on hollow hubs which are keyed to a rotatable vertical shaft. Reading arms are provided between each pair of discs and are mounted on a common shaft rotatable under the control of a mechanical aggregator to select a desired one of 256 circular tracks on each disc. Mechanical aggregator. In one arrangement, Fig. 17, the aggregator comprises a plurality of triangular linkages, such as 365, each adapted to expand longitudinally by a distance corresponding to a corresponding digit of a binary address supplied by a computer. The address may comprise an eight-digit binary number which is compared, digit by digit, with the existing state of the aggregator in an electric circuit (not shown). For each stage wherein a charge is required an electrically operated clutch is energized to couple a cam disc 360 to a continuously rotating shaft; this causes the stage to move to its other state via a cam follower 362 and lever 363 acting on the apex 364 of the corresponding linkage. In another arrangement, Fig. 19, the triangular linkages are replaced by helical racks 380 coupled by spindles 381 carrying spaced helical gears 382 meshing with adjacent racks, the angle of slope of gears 382 varying from stage to stage in binary order. Each spindle is rotatable by a cam follower 382 co-operating with a cam 370 which is either coupled to a brake 375 or coupled by a clutch 374 to a continuously rotating shaft 371. A commutator disc 376 is coupled to the cam 370 and carries two tracks 377 and 378 each having two 90 degrees conducting segments. " 0 " and " 1 " signals are supplied by the address from a computer to wipers (not shown) engaging the tracks. If no change is required the corresponding wiper is adjacent a non-conducting segment; if a change is required the signal on the wiper passes to a relay (not shown) which energizes the clutch 374 until the cam has rotated a quarter of a revolution; and then the clutch is de-energized and the brake re-energized. The movable end of the aggregator operates a servomotor which applies the required rotation to the read-arms, and may also operate an indicator to show which track has been selected. The coupling between the aggregator and the servomotor may be operated by oil pressure so that when the machine is idle, the heads are swung clear to allow records to be changed. Positioning playback heads.-The heads 303, 304, Fig. 11, between a pair of discs 301, 302 are universally mounted on respective arms 308, 307. In the playback position shown the arms 307 and 308 are forced apart by a crank 305 to bring the heads close to the discs and separated from them by air films. Fluid pressure in a cylinder (not shown) applies tension to a wire 306 to rotate the crank 305; when the heads are to be moved radially the fluid pressure is released to allow the crank 305 to return to a position where the arms 307 and 308 are in contact with each other. Indicator means.-Shaft 419, Fig. 25, is rotated in accordance with the rotation of the playback heads and carries a sector plate 454 carrying a code plate 455 indicating the four most significant binary digits of the address code. Shaft 444 is coupled to the motion of the fourth stage of the aggregator, i.e. follows the four least significant binary digits of the address, and is coupled by a lever 459 and worm 460 to a sector plate 462 carrying a code plate 463. The code plates may be read electrically by lamps 456, 465 and associated photo-cells 457, 466, the lamps and photo-cells 456, 457 being carried on an arm 453 rotated by lever 459. The code may comprise four rows of apertures in the code plates and each reading array may comprise four lamps and four cells. Specification 1,017,132 is referred to.