| 摘要 |
PURPOSE:To enable erroneous operation of a printing head at a high temperature to be prevented by a traditional material as it is, by a method wherein a bias voltage compensating for a difference in coefficient of thermal expansion between an electrostrictive element and a lever is impressed to the electrostrictive element correspondingly to a temperature of the printing head. CONSTITUTION:When heat is generated in a printing head part and its temperature is increased, the temperature is detected with a thermister TM of a temperature detection circuit 22, and a signal corresponding to the detected temperature is sent to a CPU 14b via an A/D converter 14a. The CPU 14b computes how many volts of DC bias voltage VDC is preferably impressed to the electrostrictive element to be electrically stricted from a value of coefficient of thermal expansion of the electrostrictive element of the printing head according to the detected temperature, and impresses it as a control voltage Vic of the DC bias voltage to a base of a transistor TR 8 of a voltage control circuit 14d via a D/A converter 14c. Therefore, the bias voltage VDC varies by a content by which a control voltage Vi of the DC bias voltage is impressed to the base of the transistor TR 8, and a voltage VC at both ends of the electrostrictive element also varies by the bias voltage VDC. Therefore, even though temperature of the printing head part increases to a considerable high temperature, stable printing operation is performed. |
