| 摘要 |
PURPOSE:To obtain a printing apparatus securing printing of high quality without being affected by a change in temperature, by providing a means for compensating temperature which makes a driving current for printing hammers variable in accordance with the change in temperature, so as to make a printing pressure constant. CONSTITUTION:A driving signal HMR supplied to a NAND gate 1 makes a transistor 3 continuous through the intermediary of an inverter 2 and excites a printing hammer 4. The current value of a driving current exciting the hammer 4 is detected by a detector 6, and a detection value is supplied to the input terminal of a comparator 7. The comparator compares the output values (a) of the detector 6 and a driving current controlling circuit 9 with each other, and delivers the result of comparison to the gate 1. When the output (a) of the detector 6 is higher than that (c) of the circuit 9 on the occasion, the output of the comparator 7 changes from ''1'' to ''0'', and thereby the excitation of the hammer 4 is discontinued forcedly through the intermediary of the gate 1. When it is lower, to the contrary, the output (b) of the comparator 7 returns from ''0'' to ''1'', and thereby the excitation of the hammer is conducted. |
