| 摘要 |
PURPOSE:To prevent a printing head from being overheated, by a construction wherein core-pieces of U-shape are radially arranged correspondingly to the arrangement of drive arms and each integrally connected to an annular portion at the tip end portion of the outside leg-piece thereof forms an assembly. CONSTITUTION:Drive arms 11 are radially arranged and integrally connected at the rear ends thereof. A core built-up body, consisting of a magnet plate 14, a permanent magnet 15, and a core body 16, is bonded together as a unit. The core built-up body is connected to a drive arm built-up body through a ring-form spacer 17 by a screw 18. Respective core-pieces 16a are radially arranged correspondingly to the arrangement of the drive arms 11 and integrally connected through an annular portion 16b. Conduction of a drive coil 19 eliminates the flux of the permanent magnet 15, which allows the drive arms 11 to move forward owing to their own elastic force to advance printing wires 7 against th force of return springs 9, thus forming a dot. In this manner, the heat generated in the drive coil is made to disperse outside through spaces 16c formed between the core-pieces, which enhances the durability of a printing head. |
