Ex parte REINER et al. - Page 5

                                                                                                                                      Page 5                        
                   Appeal No. 1998-1373                                                                                                                             
                   Application No. 08/377,473                                                                                                                       

                   filter stages in series, and it would have been obvious to one of ordinary skill in the art to                                                   
                   provide the Heyl apparatus with a second filter stage in view of this teaching.                                                                  
                            Clark discloses an apparatus for removing particles from the air (Abstract).  It                                                        
                   discloses a housing (11) that is partitioned by a plate (21) on which is mounted a                                                               
                   motorized impeller (16).  A first filter unit (41) is positioned on the downstream side of the                                                   
                   partition, and a second filter unit (63) is located upstream of the partition with its inlet in                                                  
                   communication with the outlet of the first filter unit.  The impeller causes air to move through                                                 
                   the two filter units.  The second filter unit receives the air that has passed through the first                                                 
                   filter unit, and comprises a HEPA filter which traps sub-micron particles (column 5, line 62                                                     
                   et seq.).                                                                                                                                        
                            From our perspective, one or ordinary skill in the art would have been taught by                                                        
                   Clark that the use of a second filter unit in series with the first results in more effective                                                    
                   filtration, and therefore would have found it obvious to add a second filter unit to the Heyl                                                    
                   apparatus.   Suggestion for such a modification is found not only in the explicit teaching of                                                    
                   Clark that a second filter will improve the efficiency of the filtering process, but also in the                                                 
                   self evident advantages of passing a product to be filtered through a plurality of filters                                                       
                   arranged serially, which would have been known to the artisan.   It therefore is our                                                             

                            2Skill is presumed on the part of the artisan, rather than the lack thereof (see In re                                                  
                   Sovish, 769 F.2d 738, 742, 226 USPQ 771, 774 (Fed Cir. 1995)).                                                                                   

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