Industrial robot hand with position sensor

Claim 1

A robot for transporting a semiconductor wafer comprising: robot hand means for engaging and retaining a semiconductor wafer, said robot hand means including first support means for supporting the retained semiconductor wafer and second support means for supporting said first support means, position sensing means located on said second support means for detecting the presence and exact position of the semiconductor wafer on said robot hand means, said position sensing means including first sensor means and second sensor means, said first sensor means including first and second sensors spaced apart and positioned so as to not be covered by the semiconductor wafer in its correct position, said first and second sensors each having a center, said second sensor means including a third sensor equidistant from said first and second sensors and spaced from a line drawn between said centers of said first and second sensors and positioned so as to be covered by the semiconductor wafer in its correct position, and said first sensor means and said second sensor means together indicating if the semiconductor wafer is present and in a correct position.