| 摘要 |
PURPOSE:To make it possible to keep density constant, by performing the supply of a current for a predetermined time shorter than a time imparting a printable level at the initial time of start and performing current supply control at a time interval shorter than the above-mentioned current supply time during a period free from printing data. CONSTITUTION:When a power source 2 is closed, a printer main circuit 1 supplies a voltage pulse from the power source 2 over a predetermined time width T1 allowing a thermal head 4 not to reach printable temp. but to rise in temp. to a certain degree to preheat the thermal head 4 and, thereafter, performs preheating control at time interval T2 for a time width T3 capable of holding the temp. of the head 4 to scheduled temp. lower than a printable temp. level until a printing order arrives. Because the thermal head 4 already reaches predetermined preheating temp. by the above-mentioned preheating control, when the thermal head 4 receives a voltage pulse for printing, the temp. thereof immediately rises to the predetermined printable level. Therefore, printing free from density irregularity is enabled. |
