| 摘要 |
PURPOSE:To inexpensively obtain an angular velocity changing mechanism, in a high speed dot matrix printing apparatus, by rotating a shaft to be rotated and a drive shaft so as to shift the axes thereof to each other while providing a reduction gear mechanism between the shaft to be rotated and the shaft of a main eccentric disc cam. CONSTITUTION:When a constant speed rotary motor 2 is rotated, angle velocity changes in a pattern of max. min. max. during one rotation of a disc 8 with a U-groove because the axis of a drive disc 6 is eccentric to the axis of the disc 8. In addition, a reduction gear mechanism consisting of a belt 14 and speed decreasing gears 10, 13 is interposed between an eccentric disc cam 1 and the disc 8 with the U-groove in order to set a rotation number to 1:2 and the speed change of a frame 16 to be driven having a printing head 20 fixed thereto is coincided with the angular velocity changing cycle of the disc 8 with the U- groove. Furthermore, the eccentric direction of the eccentric disc cam 1 and the U-groove direction of the disc 8 are shifted by 90 deg. in a phase and an average sweep speed is raised without raising a max. sweep speed to enhance a printing speed. By this mechanism, high printing quality can be inexpensively obtained. |
