| 摘要 |
<p>PROBLEM TO BE SOLVED: To detect presence or absence of a substrate and deviation of the substrate from a blade on which the substrate is mounted while the substrate is transported by exciting the blade and measuring outputs of a vibration frequency and each frequency by a vibration detector. SOLUTION: A vibration exciter 4 and a vibration detector 5 are fixed to the rear surface of a blade 2 of a wafer carrier robot 3. When a wafer is placed at its normal location for the blade 2, the blade 2 is exited by the vibration exciter 4, vibration of the blade 2 is measured by a vibration detector 5, the output is passed through a band pass filter and the output is defined as an output A. When a wafer is not mounted on the blade 2, a frequency changes for the natural frequency when the wafer is placed at its normal location in the natural frequency of this system. When the output of the vibration detector 5 is passed through the band pass filter, the output becomes smaller than A. Thus, a large difference is generated between an output in a state that the wafer is mounted and output in a state that the wafer, and presence or absence of the wafer can be detected.</p> |
