| 摘要 |
PURPOSE:To enable uniform driving characteristics to be easily obtained for each printing element, by providing each electromagnetic driver for driving each driving arm with a magnetic resistance regulating means for varying the magnetic resistance of a magnetic circuit of the driver. CONSTITUTION:A magnetic circuit for an electromagnetic driver is constituted of a movable yoke 11b, a core piece 16a and a magnet 15. Each of such magnetic circuits is provided with a magnetic resistance regulating means 18. For example, each core piece 16a is provided with a through-hole 16b, and a support plate 19 formed of a non-magnetic material and fitted to the back of a core piece 16 is provided with a threaded hole 19a opposed to the through-hole 16b. A threaded part provided at a head part of an adjusting pin 20 formed of a magnetic material is engaged into the threaded hole so that the pin 20 can be moved forward and retracted in the through-hole 16b. After a printer head is assembled, the adjusting pins 20 corresponding respectively to all printing elements 7 are moved forward or backward 10 regulate the magnetic resistance of the magnetic circuit of each magnetic circuit, whereby an attractive force between the movable yoke 11b and the core piece 16a is balanced with a spring force of a driving arm 11, with the result that rise characteristics and printing characteristics of all of the printing elements are uniformized. |
