Patent GB-1528338-A (GB)
Title: Transducer head carriage assembly for magnetic disc apparatus
IPC: G11B17/32
Filed: 1976-04-07
Abstract: 1528338 Magnetic head supports; magnetic disc apparatus INTERNATIONAL BUSINESS MACHINES CORP 7 April 1976 [21 April 1975] 14060/76 Heading G5R A carriage 70, Fig. 7, supports facing, aligned magnetic heads 150, 152 for co-operation with the opposite sides of a magnetic disc 20, the heads being mounted to allow easy pitch and roll relative to the local disc/head movement direction and being pressure loaded towards the disc by respective leaf springs 176, Figs. 10, 11, (184), Figs. 12, 13 (not shown), and load arms 182, (186) acting via respective domed universal pivots 176h, Fig. 10, (184h), Fig. 12, which lie on a line perpendicular to the disc surfaces, the springs 176, (184) also having parts on which the heads are mounted. The leaf spring 176, Figs. 10, 11, has base parts 176a, 176b and narrow legs 176e, 176d joined by a cross piece 176f having a widened central part 176g on which the head 150 is mounted. The relatively rigid load arm 182 is welded to spring part 176c and has an end part 182g bearing on a dimple 176h which is on part 176g and forms the universal pivot. The part 176b has a set so that the spring 176 would be bent as at 176x, Fig. 10, if unrestrained. Load arm 182 under the influence of spring parts 176b loads the head 150 towards the disc and resistor head motion perpendicular thereto, while parts 176d, 176e, 176f, 176g function as gimbal springs allowing easy pitch, and roll motions of head 150 about pivot dimple 176h. The head 150 may have a flat working face to contact the disc or may have a bevelled leading edge so that it flies relative to the disc. Head 150 has a read/write core (154), Fig. 9 (not shown), two erase cores (156) laterally either side of core (154), and windings 162, Fig. 10. Spring (184), arm (186) and head 152 are similar. A magnetic disc apparatus has a cover (36), Fig. 2 (not shown), which can be pivoted open so that a magnetic disc 20, Fig. 7, in an envelope (22), Fig. 1 (not shown), can be inserted into slots (40), Fig. 2, the disc centre being gripped between a spring biased collet (66) on cover (36) and a head (48) of a rotating disc drive shaft (46) on closing cover (36). The carriage 70, Fig. 7, is movable on rods (76), (78), Fig. 5 (not shown), radially of the disc by a motor (84) and belt (86), Fig. 4 (not shown), and has parts 72, 74, Fig. 7, on opposite sides of the disc 20. Swing arms 104, 106 are attached by leaf springs 108, 110 to carriage parts 72, 74. A block 178, Fig. 10, fixed to the base 176a of the leaf spring 176 of the above head support is bolted to arm 104, and the other head 152 and support assembly (184), (186) is bolted to arm 106 so that the heads 150, 152 are opposite each other. To prevent cross-talk between the heads 150, 152, the cores are non-central in the head blocks so that the cores in head 150 are displaced radially inwardly, e.g. by 3 or 4 tracks on disc 20, relative to the cores in head 152. To withdraw or insert a disc, an electromagnet (130), Fig. 5, is de-energized so that a spring (140) pulls a lever (142) to engage a hook (148) on swing arm 104 whereby arm 104 and, via an interconnection 104a, 106a, Fig. 7, arm 106 are swung outwards from their operative positions against stops 72b, 74b to move heads 150, 152 away from the disc 20. To effect  such movement arm 104 is coupled to head 150 via a first lost-motion connection formed by arm parts 104b engageable with wings 182c, Fig. 11, on load arm 182, and a second lostmotion connection formed by fingers 182m on load arm 182 engageable with crosspiece 176f of spring 176. The various parts of the lost motion connections are disengaged in the operative position so that head 150 floats freely. Arm 106 is similarly linked to head 152. To assume the operative state, electromagnet (130) is energized thereby pivoting lever (142) out of engagement with arm 104 so that return springs 118, 122, Fig. 7, urge arms 104, 106 back to the operative position in which the assembly of the disc 20 and its envelope (22) is gripped between a pressure pad (146), Fig. 5, on the lever (142) and a platen (44).