Browse Prior Art Database

Air Transport Collision Avoidance Device

IP.com Disclosure Number: IPCOM000078262D
Original Publication Date: 1972-Dec-01
Included in the Prior Art Database: 2005-Feb-25
Document File: 2 page(s) / 27K

Publishing Venue

IBM

Related People

Bertelsen, BI: AUTHOR

Abstract

This device provides a means to prevent collision between a stationary object, such as a semiconductor wafer, held by a vacuum stop on an air track and an approaching object.

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Air Transport Collision Avoidance Device

This device provides a means to prevent collision between a stationary object, such as a semiconductor wafer, held by a vacuum stop on an air track and an approaching object.

An air track of typical construction is provided with vacuum stops 1 and 2 connected to a vacuum supply through tubing, as shown. A solenoid valve allows the vacuum to be turned on or off at vacuum stop 2. A restriction between the vacuum supply and vacuum stop 1 allows for a reduction of applied vacuum to vacuum stop 1 insufficient to stop an approaching object, as long as no object is present at vacuum stop 2 and the solenoid valve is open. Initially, the solenoid valve is open allowing full vacuum to be applied to vacuum stop 2. A first wafer moving in the direction shown is not stopped at vacuum stop 1 due to insufficient vacuum, but is stopped at vacuum stop 2. A second wafer is prevented from colliding with the first wafer due to the increase in vacuum at vacuum stop 1, caused by the first wafer blocking vacuum stop 2. When the solenoid valve is closed, the first wafer will continue to move along the air track. The second wafer will remain stopped at vacuum stop 1, until the solenoid valve is reopened and the vacuum at stop 1 is again reduced.

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