Precision apparatus having a movable member, an air slit and a vacuum duct

Abstract

A precision apparatus has a movable member (A), moving in a bridge element ( 2 ) arranged perpendicular to the movement of the moveable element. The bridge element comprising an air slit (S) and a exhaust (E). The bridge element ( 2 ) comprises a primary air duct ( 21 ), substantially extending along the length of the bridge element, which primary air duct is provided with apertures ( 21 a , 21 b ), The apertures ( 21 a , 21 b ) are evenly distributed along the length of the bridge element, and form an air flow passage to a secondary air duct ( 22 ), also substantially extending along the length of the bridge element Through the secondary air duct in operation air is drawn through the air slit (S).

1 . A precision apparatus having a movable member (A), moving in a bridge element ( 2 ) arranged perpendicular to the movement of the moveable element, said bridge element comprising an air slit (S) and a exhaust (E), wherein the bridge element ( 2 ) comprises a primary air duct ( 21 ), substantially extending along the length of the bridge element, which primary air duct is provided with apertures ( 21   a ,  21   b ), evenly distributed along the length of the bridge element, said evenly distributed apertures forming an air flow passage to a secondary air duct ( 22 ), also substantially extending along the length of the bridge element, through which secondary air duct, in operation air is drawn through the air slit (S). 
   
   
       2 . A precision apparatus as claimed in  claim 1 , wherein the primary duct ( 21 ) is provided with an exhaust pipe (E 1 , E 2 ) at opposite sides, seen along the length of the bridge element, of the primary air duct. 
   
   
       3 . A precision apparatus as claimed in  claim 1 , wherein the secondary air duct ( 22 ) at least partially encases the primary air duct ( 21 ) and the primary air duct is provided with two opposing surfaces, each provided with apertures ( 21   a ,  21   b ), evenly distributed along the length of the bridge element, to provide an upward and downward air flow in the secondary air duct ( 22 ). 
   
   
       4 . A precision apparatus as claimed in  claim 1 , wherein the primary duct ( 21 ) comprises an upwardly extending part ( 21   c ). 
   
   
       5 . A precision apparatus as claimed in  claim 1 , wherein the primary duct comprises a downwardly extending part ( 21   d ).