| 摘要 |
PROBLEM TO BE SOLVED: To obtain a desired contact pressure using a comparatively smaller spring force and make a thermal printer small-sized and lightweight by providing a tension spring between the end part of a head retainer which retains a thermal head and the end part of a platen roller shaft and pressing the thermal head toward the platen roller with the spring. SOLUTION: Engagement pieces 4c, 4d which engage one of the ends of a tension spring are provided on both upper ends of a head retainer 4, and metal tension springs 5a, 5b are tensely mounted between the engagement pieces 4c, 4d and the bearing fitments (11a), 11b of a platen roller shaft 2a. The positions of the engagement pieces 4c, 4d are present almost in the extension of a face running through the center of a platen roller 2 and the center of a contact face between a thermal head 3 and the platen roller 2. Consequently it is possible to efficiently convert the spring force of the tension springs 5a, 5b to a contact pressure and therefore, use a spring having a small spring force. Thus a head indicator of comparatively smaller thickness can be used to reduce the weight of a thermal printer.
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