| 摘要 |
<p>PURPOSE:To control movement with a high precision by providing a cooling means which cools a stage driving means as a heating body and controlling the cooling means so that the temperature difference between a base and a linear motor is zero. CONSTITUTION:When the temperature of a coil rises by the heat generated by a coil 11 of the linear motor, temperatures of a yoke 12 and a spacer 13 surrounding this coil rise, and resistance values of temperature sensors 9 and 9 attached to a temperature sensor attaching pit 14 are increased. Meanwhile, resistance values of reference temperature sensors 30 and 30 attached to the base are not changed because the rise of temperature of the base is slower than that of the yoke of the linear motor. Consequently, the balance of a temperature difference detecting bridge circuit is lost to generate an output voltage. This voltage is amplified to open a solenoid valve. Since the solenoid valve is opened, a refrigerant sent with a pressure by a pump is led to a linear motor cooling duct (refrigerant path 16) through a flexible tube 22 to remove the heat. Thus, the temperature difference between the linear motor and the base is approximated to zero by this control circuit.</p> |
