Glatt's invention applies coats to particles such as pharmaceutical ingredients.

This case involves the Federal Circuit reversing the U.S. Board of Patent Appeals and Interferences decision that claim 5 of US5236503 was obvious.

Claim 5 follows as:

In a fluidized bed coater having a product container opening upwardly into an expansion chamber and downwardly into a lower plenum chamber through an air distribution plate/screen having openings formed therethrough for upward air flow from said lower plenum chamber into said product container, said product container including a substantially cylindrical partition spaced above said air distribution plate/screen for defining an inner upbed area and an outer downbed area, and an upwardly discharging spray nozzle mounted substantially centrally within said cylindrical partition, the improvement comprising shielding means positioned adjacent said spray nozzle for shielding the initial spray pattern developed by said nozzle against the entrance of particles moving upwardly through the upbed. 

The initial obviousness rejection was on the basis of a german patent DE 3323418:

Naunapper describes the removal of agglomerates by "blowing through" with increases air flow. Based on this, the PTO examiner found the device claimed for "shielding means" and made a case for obviousness (1)

The Federal Circuit disagreed and stated that Naunapper can be used to "(1) circulate particles and (2) clear blockages. The air source cannot perform both of these functions simultaneously, and more importantly, neither of these functions constitutes shielding" (1). In doing so, the Federal Circuit determined that PTO failed to make a case for obviousness.

Sources
(1) https://www.pharmapatentsblog.com/2011/01/06/an-ounce-of-prevention-can-be-patentable-over-a-pound-of-cure/