Apparatus providing a gaseous support bed and method for treating glass or the like thereon

Claim 1

IN A APPARATUS FOR TREATING A SHEET OF GLASS WHILE SUPPORTING THE SHEET ON GASES AND TRANSFERRING HEAT BETWEEN THE SHEET AND THE GASES, AN ELONGATED BED AND THE MEANS FOR GUIDING A SHEET OVER SAID BED LONGITUDINALLY THEREOF, SAID BED HAVING A FIRST LONGITUDINALLY EXTENDING ZONE WITH FLUID INLET PERFORATIONS THEREIN FOR FLOATING SAID SHEET RELATIVELY HIGH OVER AND OUT OF CONTACT WITH SAID BED IN SAID ZONE, A SECOND LONGITUDINALLY EXTENDING ZONE WITH FLUID INLET AND FLUID EXHAUST PERFORATIONS THEREIN FOR FLOATING SAID SHEET RELATIVELY LOW OVER AND OUT OF CONTACT WITH SAID BED IN SAID ZONE, AND A FLOAT TRANSITION ZONE INTERMEDIATE SAID FIRST AND SECOND ZONES AND HAVING FLUID INLET AND FLUID EXHAUST PERFORATIONS THEREIN, THE RATIO OF THE AGGREGATE CROSS-SECTIONAL AREA OF THE FLUID EXHAUST PERFORATIONS OVER THE AGGREGATE CROSS-SECTIONAL AREA OF THE INLET PERFORATIONS IN THAT PORTION OF SAID TRANSITION ZONE ADJACENT SAID FIRST ZONE BEING LESS THAN THE RATIO OF THE AGGREGATE CROSS-SECTIONAL AREA OF THE FLUID EXHAUST PERFORATIONS OVER THE AGGREGATE AREA OF THE FLUID INLET PERFORATIONS IN THAT PORTION OF SAID TRANSITION ZONE ADJACENT SAID SECOND ZONE THEREBY TO CAUSE THE SHEET TO DROP GRADUALLY FROM A HIGH FLOAT POSITION OVER SAID FIRST ZONE TO A LOW FLOAT POSITION OVER SAID SECOND ZONE.