MARTEAU POUR IMPRIMANTE A MATRICE DE POINTS

LE MARTEAU 22 PORTE UNE BOBINE PLATE 42 ET COMPREND UNE PARTIE DE SUPPORT 38 ET UN MOYEN 48 POUR MONTER LADITE PARTIE 38 SUR LA TETE D'IMPRESSION, DES MOYENS DE DISSIPATION DE CHALEUR 58, 60 COMPRENANT UNE FEUILLE DE MATIERE THERMIQUEMENT CONDUCTRICE ETANT PREVUS POUR DISSIPER LA CHALEUR PRODUITE DANS LA BOBINE PLATE 42.APPLICATION AUX IMPRIMANTES. Each hammer includes a frame-like portion with a recess into which an electrically energizable flat coil is received. Affixed to opposite sides of the frame portion, and extending therefrom over the recess in contact with the sides of the coil, are thermally conductive metallic foil sheets which serve to dissipate heat from the coil, retain the coil intact and maintain the proper position of the coil relative to the frame. The exterior surfaces of the sheets form bearing surfaces to protect the hammer and coil from wear caused by contact with other parts of the head as the hammer is displaced. An elongated recess is formed along the axis of a portion of the frame, in the direction of displacement, by cutting transverse slots therein so as to form a plurality of clamping elements, alternate ones of which are situated on opposite sides of the axis. A print wire is received within the recess and frictionally engaged by the elements so as to form a strong rigid joint without significantly increasing the mass or thickness of the hammer. The print wire is affixed to the frame portion at the center of percussion thereof to eliminate torsional vibrations, otherwise created on impact.