Patent ID: 8029227

Claim:
A load port apparatus comprising: a chamber configured to maintain a higher pressure of a space interior to the chamber than a pressure of a space exterior to the chamber; an opening portion defined by a chamber wall of the chamber, the opening portion creating a passage between the space interior to the chamber and the space exterior to the chamber; a fan located at an upper side of the chamber that generates a first flow of air in the downward direction of the chamber; and a door comprising a plate configured to rest at a position at which it substantially closes the opening portion and forming a clearance between an outer circumferential surface of the plate and an inner circumferential surface of the opening portion, wherein an area of an interior cross section of said clearance between the plate and the opening portion on a plane flush with an interior side of the chamber is larger than an area of an exterior cross section of the clearance between the plate and the opening portion on a plane flush with an exterior of the chamber, and wherein the clearance generates a second flow of air from the area of the interior cross section of the clearance to the area of the exterior cross section of the clearance, the second flow of air being separated from the first flow of air and flowing in a direction different from the direction of the first flow of air, and the second flow of air being generated by the difference in the area of the interior cross section of the clearance and the area of the exterior cross section of the clearance.