Patent GB-1170178-A (GB)
Title: Multiple Magnetic Recording Head Assemblies.
Inventor: WILLSON GORDON DANIEL HENRY
IPC: G11B5/147
Filed: 1967-11-16
Abstract: 1,170,178. Magnetic recording-head assemblies. STANDARD TELEPHONES & CABLES Ltd. 16 Nov., 1967, No. 52144/67. Heading G5R. In a multiple magnetic recording head assembly the individual recording heads are adapted for keying on to a common support member, on which they are assembled in any desired sequence, each head being in an abutting relationship with an adjacent head or with recording-head screening means which are in turn in an abutting relationship with an adjacent head; the overall width of the assembly may be varied by adding to, or removing from, the support member, individual heads, and associated screening means when provided. One of the simplest embodiments is depicted in Figs. 2A and 2B (not shown), which resembles the embodiment in Figs. 1A to 1C, described below, but differs therefrom in that the thickness of the heads is reduced, and the locating pins, locating grooves and support shaft are eliminated. As shown in Figs. 1A to 1C, each magnetic recording head 3 has a dove-tailed portion 4, a hole 6 to accommodate a support shaft 5, locating pins 7 and a corresponding groove 8. When the requisite number of heads has been slid along the dove-tail portion 2 of support member 1 into mutual contact, the shaft 5 is inserted through all the holes 6. Retaining members 9, 10, each having a dove-tail cut-out 4 and a hole 6, and one having a groove 8 and the other having locating pins 7, are provided, to be slid into contact with the ends of the array of heads. Each retaining member has a slot 11, and a clearance hole through the lefthand limb aligned with a threaded hole (not shown) in the right-hand limb, so that the member may be locked about the dove-tail portion 2 of the support 1 by means of a screw 13. Where the shaft 5, pins 7 and grooves 8 are omitted, the support member 1 may be divided into two parts 17, 18, Fig. 3B, held together by a plurality of screws 19 rotatable in part 18 and threaded through part 17; this arrangement is intended to facilitate removal of any one or more heads by screwing parts 17, 18 together at the appropriate location to reduce the effective width of the dove-tail portions. Alternatively, to facilitate removal, the dovetail cut-out in the head may be modified, one of the inclined side walls being replaced by a vertical wall; the side of the head adjacent to the vertical side wall has a tapped hole through it; when a screw engaging the hole, and normally abutting the dovetailed portion 2 on the support member 1, is unscrewed, the head may be lifted off. In Fig. 5, heads 30 are secured in position by the raising of a clamping member 38 by means of a number of screws (only one shown at 35) threaded through a projection 34 extending along the support member 29. In Fig. 6 (not shown), projection 34 and member 38 are omitted, the channel base interior is inclined, as are the bases of the heads, and each head is secured by a screw threaded through the lefthand elongated projection 33, Fig. 5, and forcing the head towards the right. Each head is made by forming a U-shaped blank of mild steel or the like into the shape shown in Figs. 9A and 9B. Limbs 48 are then bent to form polepieces, Fig. 7, an insert 54 of high-conductivity non-magnetic material is placed in the gap, a signal winding 55 is wrapped around the coil former portion 49, and the insert 54 is clamped between the polepieces by a clip 56. The insert 54 may be alloyed to the polepieces, in which case clip 56 may be omitted. In a modification, Fig. 11 (not shown), the polepieces are initially separate but are joined by the insert, and a coil former, also separate; is retained between the polepieces by a clip similar to 56.