Transport mechanism for IC handlers

A transport mechanism for an integrated circuit handler, comprising:

• a base plate having a main surface in a horizontal plane;
• rotatable contact arm means having a rotary shaft and at least three transport stations for carrying devices under test, said transport stations being disposed at equiangular intervals on a perimeter of a predetermined circle parallel to the main surface of said base plate, said rotary shaft passing through a center of the predetermined circle;
• vertically slidable shafts having respective upper and lower ends and respectively provided in said transport stations;
• a contact-in stage for feeding the devices under test, a test stage for testing the devices and a contact-out stage for taking out tested devices, said contact-in, test and contact-out stages being arranged on said base plate below said contact arm means at the same equiangular intervals as those of said transport stations and about said rotary shaft of said contact arm means on a perimeter of another circle having the same diameter as that of the predetermined circle;
• air chuck means provided at each of said transport stations, for selectively holding by suction and releasing the devices under test, said air chuck means being mounted to the respective lower ends of said vertically slidable shafts;
• a support table fixedly mounted on said base plate and extending over said contact arm means;
• air chuck driving mechanism means fixed to said support table at positions thereof above said contact-in, test and contact-out stages, respectively, for selectively moving said air chuck means up and down by pressing down respective upper ends of said air chuck means and releasing pressure applied to the upper ends of said air chuck means when corresponding ones of said transport stations are held above said contact-in, test and contact-out stages, said air chuck driving mechanism means including respective vertically movable driving shafts having respective lower ends, each of said vertically movable driving shafts pressing down the respective upper end of a corresponding one of said vertically sliding shafts with the respective lower end of said corresponding vertically movable driving shaft to lower said corresponding air chuck means when ones of said transport stations lie above said contact-in, test and contact-out stages, respectively;
• a rotary joint mounted on said support table, for rotatably supporting the rotary shaft of said contact arm means through an opening made in said support table, said rotary joint comprising:
• a second rotary shaft having at least three through holes with one ends of which are open to an outer peripheral surface of said second rotary shaft at different positions in an axial direction thereof and the other ends of which are open to a lower end surface of said second rotary shaft at different positions,
• a cylinder to receive therein said second rotary shaft, and
• a plurality of O rings, interposed between said second rotary shaft and said cylinder, for forming at least three airtightly isolated annular chambers between the outer peripheral surface of said second rotary shaft and an inner peripheral surface of said cylinder, said annular chambers being disposed in the axial direction of said second rotary shaft, each of said annular chambers communicating with one of said one ends of said through holes;
• and
• coupling means for coupling said secondary rotary shaft to the rotary shaft of said contact arm means.