PURPOSE: To cool a printing head with small power consumption without lowering printing speed and enhance durability and safety of the head, by providing fan blades formed of a shape memory alloy, rotating the fan with the blades in a flat form at and below a predetermined temperature, and rotating the fan with the blades in a shape suitable for a fan function above the predetermined temperature, thereby cooling the printing head.

CONSTITUTION: At or below a normal temperature, the blades 10a of the cooling fan 10 are maintained in a flat shape, so that even when the cooling fan 10 is rotated as a carrier 6 is moved, only the weight of the fan 10 is exerted as a load on a carrier motor 9, and no load is generated by the rotating resistance of the fan 10. With the temperature of the printing head 4 raised, the temperature of the blades 10a is raised by radiant heat from the head 4 and the heat transferred through a shaft 13 and a bearing 12. As a result, the blades 10a are deformed into the shape previously stored in the shape memory alloy constituting the blades 10a, thereby the function as the fan is displayed. Accordingly, the head 4 is cooled by the fan 10 as the carrier 6 is moved.