GB1145535A - Hammer mechanisms for printers - Google Patents

Abstract

1,145,535. Selective printing. ANELEX CORP. 29 June, 1966 [22 Oct., 1965], No. 29287/66. Heading B6F. A selective printer having a rotary type carrier (not shown) is provided with a hammer impression mechanism comprising a number of exchangeable hammer modules each comprising a plurality of hammers 2, Fig. 1, attached to alternately staggered hammer arms 4, which are mounted in dove-tailed grooves 6 of module end frames 8, the hammers 2, in their cocked positions, having their pre-stressed, resilient arms 4 held by permanent magnets 10, 12, whose fields are collapsed by selective energization of coils 14 to release the resilient arms 4 for impression of the hammers 2 against the rotary type carrier. Released hammers 2 are reset by bails 16 attached at their ends to bars 22 fast with further bars 20 which are reciprocated in the vertical plane by respective one-revolution clutch-driven cams 18. The permanent magnets 10 of the ceramic type and having fields of 2000 Gauss, are sandwiched between high permeability polepieces 12 and both magnets 10 and polepieces 12 are slotted to provide separate polepieces 40 (Fig. 3) for individual hammers, the polepieces supporting the coils 14. In a modification of the hammer module the hammer arms 4, Fig. 6, are bent at right-angles and provided with high permeability armatures 62 coacting with the permanent magnets 10, whose respective polepieces 12 support field collapsing coils 58 and resetting coils 60, the latter of which may be energized selectively or collectively. In a further modification the released hammer arms 4 (Fig. 5) may be reset by cams 54. In a final embodiment the released hammer arms 4 (Fig. 4) which are mounted in a block 44 are reset by arms 45 provided with cam followers 48 which coact with a cam 49 driven cyclically through 90 degrees. Rebound of hammers is prevented by leafsprings 39, Fig. 1, which in a modification may be provided with rubber or plastics pads 74, 76 (Figs. 9, 10).