| 摘要 |
PURPOSE:To prevent excessive heat accumulation from occurring even when high-speed driving is conducted, by providing a substrate provided with a heating resistor, a space provided in the substrate in the vicinity of the heating resistor, and a coolant provided in the space. CONSTITUTION:A heat-accumulating layer 2 provided beneath the heating resistor 5 makes contact with a coolant 17 provided in an upper chamber 13, so that the heat of the layer 2 is transmitted to the coolant 17. When a voltage is impressed on a piezoelectric element 12 to vibrate the latter, the coolant in a lower chamber 14 is caused to flow into the upper chamber 13 through one flow direction controlling valve 15, while the coolant in the upper chamber 13 is caused to flow into the lower chamber 14 through the other flow direction controlling valve 16. Therefore, the coolant 17 in the upper chamber 13 is cooled, while the coolant in the lower chamber 14 is heated. The coolant 17 in the lower chamber 14 is cooled through release of heat through a ceramic substrate. As a result, the coolant 17 cooled in the lower chamber 14 flows into the upper chamber 13, while the coolant 17 heated in the upper chamber 13 flows into the lower chamber 14, in a circulating manner. Accordingly, the heat- accumulating layer 2 beneath the resistor 5 is appropriately cooled, whereby the temperature thereof is prevented from being excessively raised. |
