| 摘要 |
PURPOSE:To enhance the cooling efficiency of thermal heads and prevent an adverse effect on ink films, by a method wherein vent holes capable of ventilation are provided either on substrates of thermal heads or within heat sinks mounted on the substrates. CONSTITUTION:A continuous printing results in the gradual heat accumulation in substrates 3a-5a of thermal heads 3-5 together with the temperature increase of a platen roller 1. Therefore, the temperature of the substrates 3a-5a gradually increases, but the heat from the substrates is conducted to heat sinks 15-17 provided on the substrates 3a-5a as an integral part and thereby the temperature increase of the substrates is inhibited. On the other hand, the heat sinks which were increased in temperature are cooled to decrease in temperature due to the air-blasting from a fan 21 to vent holes 18-20 provided in the heat sinks. The repetition of this process prevents the thermal heads 3-5 from abnormally increasing in temperature. Fins 15a-17a formed on the inner walls of the heat sinks improve the heat exchange property between the heat sinks and the air-blasting. The air-blasting by the fan 21 is conducted into the vent holes 18-20; thus, there is no possibility that this air flow affects adversely on ink films 6-8. |
