摘要 |
<p>PURPOSE:To prevent the damage of a semiconductor wafer by stopping a motor when the currents of the motor exceed the specified value above normal load currents after the lapse of a specified time after the point of time when the motor has operated. CONSTITUTION:This is provided with current detectors 29-32, which detect the currents of DC motors 3, 9 and 18, alarm devices 38-41, and motor control means 34-37, which are connected to said current detectors 29-32. And the motor control means 34-37 respectively stop the DC motors 3, 9, 15 and 18 when the currents of the DC motors 3, 9, 15 and 18 have exceeded the values 1.2 times the normal load current average values after the lapse of, for example, 0.1 second from the points of time when the DC motors 3, 9, 15 and 18 were operated, and also issue alarms from alarm devices 38-41. Accordingly, it prevents the stress above the specified value from occurring in the semiconductor wafer. Hereby, it can prevent the semiconductor wafer from being damaged.</p> |