GB1478541A - Electromagnetic drive element and printing head for dot-matrix printer - Google Patents

Abstract

1478541 Electromagnets TELE SPEED COMMUNICATIONS Inc 17 Sept 1974 [17 Oct 1973 25 Oct 1973] 40517/74 Heading H1P A dot-matrix printing head 10 (Fig. 1) comprising a circular array of electromagnets disposed round the central axis of the printed character is mounted on upper and lower carriage bearing shafts 12, 14 on a base having legs embracing shaft 12 with clamps 22 for timing belt 24 driven to traverse the head 10 along the shaft. Baseplate 26 of the head supports the print mechanism and is integral with the legs with an upwardly extending bridge 28 carrying a wire bearing transition plate 30, a bridge 32 with ribbon guides, and an adjustable aperture wire collector bearing plate 34. A boss 36 of baseplate 26 mounts inner and outer electromagnet array plates 38, 40. Plural electromagnets 52 are radially spaced and bracketed on the plates 38, 40 round the periphery of the base thereof, and magnets each have an I core mounted at an angle to the printing axis. Magnet 52 (Figs. 4, 5) comprises magnetizable core 60 with integral poles 54, 62 on one of which a leaf spring 64 is slot mounted and screw secured to carry a shoe 67 and a magnetizable gapped armature 66; the shoe carrying a printing wire 68 and the magnet being energized by winding 70. The spring is of steel or beryllium copper, and the armature 66 is undercut to enable it to move freely ; being at the same time screwed to the free end of the spring so that its inner end extends into recess 80 of the pole 54. Surface 88 of pole 92 is spaced from the secured end of the shunt and on energization the spring 64 is deflectable so that gap 90 is closed and the surfaces of the shunt and the pole are in contact. The magnet assembly is mounted at an angle to the centreline of the printed character, and the shoe 67 is rigid to carry print wire 68 of e.g. electropolished tungsten which extends to the printing medium to contact the latter on energization. The impact force increases as gap 90 closes. The print wires of the several magnetic assemblies extend through discrete guide apertures of transition plate 30 and through a common rectangular guide aperture of bearing plate 34 adjacent the printing face defined by platen 104 cooperating with paper guides 102.