| 摘要 |
PURPOSE:To perform stable printing regardless of temp., by providing an energizing spring composed of a shape memory alloy constituted so that the base part thereof is arranged in close vicinity to a coil positioned in an annular form and the leading end thereof is brought into contact with an armature. CONSTITUTION:A magnetic circuit containing a guide 1 and a head frame 2 and consisting of a yoke 4 having a plurality of coils 3 mounted thereto in an annular form, a permanent magnet 5 and an armature 7 having a wire 6 mounted to the leading end thereof is mounted. An energizing spring 8 composed of a shape memory alloy and an energizing spring base 9 are provided in close vicinity to the coil 3, and the bottom plate 10 holding the bottom surface of the energizing spring base 9 and the rear cover 11 hermetically closing the rear of a printing head are mounted. The energizing spring 8 is present on the circular edge of the cylindrical energizing spring base 9 in a fin-shape as a leaf spring and the number of the springs 8 are equal to the number of the armatures 7. The energizing spring 8 extends at a temp. threshold value or more and bent from the root part thereof at the temp. threshold value or less. Since the armature 7 is energized by the energizing spring 8 when the temp. of the printing bead becomes the temp. threshold value of the shape memory alloy or more, the motion speed same to that at the time of low temp. can be obtained. |
