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Browse Prior Art Database

Detection Technique for Automatic Article Transport Systems

IP.com Disclosure Number: IPCOM000088608D
Original Publication Date: 1977-Jul-01
Included in the Prior Art Database: 2005-Mar-04
Document File: 2 page(s) / 43K

Publishing Venue

IBM

Related People

Raacke, KH: AUTHOR

Abstract

Article transport systems and especially those utilizing vectorized gas jets to effect travel over a particular path use, among other means, a photoelectric and vacuum means for sensing the article at a specific location. This system provides a means for interrupting a light beam and the resultant activation of a vacuum stop. This arrangement is and has been adaptable to the transport of semiconductor wafers from one processing station to another.

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Detection Technique for Automatic Article Transport Systems

Article transport systems and especially those utilizing vectorized gas jets to effect travel over a particular path use, among other means, a photoelectric and vacuum means for sensing the article at a specific location. This system provides a means for interrupting a light beam and the resultant activation of a vacuum stop. This arrangement is and has been adaptable to the transport of semiconductor wafers from one processing station to another.

It was found that reflecting a light beam from a permanently fixed surface, e.g., double mirrors, and not from the article surface in the plane of travel of a semiconductor wafer, would provide a better fail-safe system and avoid or minimize sensing component failure interruptions.

Referring to Fig. 1, a control box 1 is provided in close proximity to the travel surface from which a light source 2 is directed to semiflanged mirror 3 so that the light path is directed from one flanged section 4 to the opposing flanged rim 5 of the mirror and then to a sensor 6. This mirror-light interruption system is angularly arranged (Fig. 2) so that, as the wafer 7 interrupts the light at the first station, the application of vacuum forces the wafer to rotate and in effect center itself before complete application of vacuum at the interruption of the second light source.

This procedure allows for more adequate control of article positioning. The sensing means is located befo...