IMPACT TYPE SERIAL PRINTER

PURPOSE:To contrive to raise a quality of a printing by regulating a parallelism of a printing head and a platen on the basis of a printing pressure automatically and with high accuracy. CONSTITUTION:A printing head 1 is conveyed along a platen 6 by means of a guide shaft 5 arranged on base plates 3, 4. An eccentric shaft 5a is set with its projecting state on a left edge section of the guide shaft 5, a coaxial thin shaft 5b is set with its projection on its right edge section and a shaft engagement in a bearing is executed freely to rotate through both base plates. A gear 8d is fixed on a projecting edge from a base plate 3 of the eccentric shaft 5. A driving motor 8a is fixed on a base plate 3 and a rotation of a driving gear 8b of this motor is transferred to the gear 8d through a transmission gear 8c. In a face 6a opposing the printing head 1 of the platen 6, four sensors 9a, 9b and 9d are built in with a space so as to form the same face as the face 6a. A printing pressure of the printing head 1 is detected by the sensors 9a, 9b, 9c and 9d, their detection signals are supplied to a control circuit, a guide shaft 5 is rotated by controlling a driving of the motor 8a and a parallelism of the printing head 1 and the platen 6 is regulated.