Apparatus and method for positioning a cassette pod onto a loadport by an overhead hoist transport system

摘要

An apparatus and a method for positioning a cassette pod onto a loadport of a process machine by an overhead hoist transport system are disclosed. The apparatus consists of four sensor plates each equipped with a connecting rod, a compressible spring and a vibration sensor. The apparatus further includes a concave mirror mounted on a bottom surface of a cassette pod and a light source and a photosensor mounted at a center location on the loadport. The apparatus further includes a process controller for receiving a signal from the photosensor indicating an incorrect position of the cassette pod and then sending a second signal to the OHT system such that the position of the OHT can be corrected and calibrated accordingly to position the cassette pod on the loadport in an accurate manner.