GB827165A - Improvements in information storage arrangements employing magnetic drums - Google Patents

Abstract

827,165. Electric digital-data-storage apparatus. DIRKS, G. Jan. 25, 1957, No. 1106/58. Divided out of 827,163. Class 106 (1). Information storage apparatus comprises a rotatable magnetic drum with a plurality of tracks, at least one movable transducing head associated with the drum, and electromagnetically-controlled selecting means for moving the head into effective relationship with a selected track. As described, two heads 4 and 5, Fig. 3, each adapted to co-operate with a separate drum, are mounted on a plate 6 which is supported by a sleeve 7 on a shaft 8 and can be rocked slightly to one side or the other so as to bring either head into effective relationship with its associated drum. Movement of the plate 6 is controlled by solenoids 21 and 22 one of which, when energized, displaces an armature 20 which is resiliently coupled to the plate by spring members 23, 24 engaging slots 25 in the plate 6. One of two sets of contacts 29, 30 is closed during such a displacement, by a projection 28 to complete the circuit to the selected head, or to indicate the movement in a checking circuit. Springs 26 return the armature to the central position. The assembly shown in Fig. 3 is moved along the shaft 8 to select different tracks on the two drums either by an eccentric (Fig. 2, not shown) connected by a link to the shaft 8 and driven from a transverse shaft, or by a rack-and-pinion arrangement (Fig. 6, not shown). The amount of such movement is determined by a commutator 31, Fig. 5, co-operating with a series of brushes 34 each associated with a track position. To select a track, one of a series of switches 42a is closed, whereby unless its associated brush is already on an insulating segment 32, a circuit is completed for a solenoid 41 which removes a stop 39 from a ratchet-wheel 13 integral with the commutator 31. This allows a constantlyrotating shaft 35, working through a friction clutch 36, 37 to rotate the ratchet-wheel-commutator assembly until the insulating segment 32 breaks the circuit of the solenoid 41. The stop 39 then arrests the ratchet-wheel 13 and the heads 4 and 5 are held opposite the selected track. Instead of rocking the heads into contact with the drum surface a roller 27 may be mounted adjacent each head to maintain a small air gap. A plurality of assemblies such as shown in Fig. 3, may be mounted on the shaft 8.