Patent ID: 7090222

Claim:
A shaft sealing assembly for use in a vacuum processing apparatus, comprising: a vacuum casing formed therein with a vacuum chamber maintained at a high pressure level less than 10 −1 Pa, said vacuum casing having a base portion formed with an opening wherein said opening provides communication between said vacuum chamber and the atmosphere; a driving shaft having an outer cylindrical surface and movably extending in said vacuum chamber of said vacuum casing through said opening of said vacuum casing; and a sealing ring in the form of an annular ring shape, received in said opening of said vacuum chamber and including a sealing lip held in contact with said outer cylindrical surface of said driving shaft and formed with an annular groove, an annular spring member received in said annular groove of said sealing lip and operative to impart a force to said sealing lip to ensure that said sealing lip is held in tight contact with said outer cylindrical surface of said driving shaft, and a peripheral portion radially outwardly extending from said sealing lip and fixedly connected with said base portion of said vacuum casing, in which said outer cylindrical surface of said driving shaft is smaller in surface roughness Ra than 0.1 (μm) and the gap between said outer cylindrical surface of said driving shaft and said sealing lip of said sealing ring is sealed within a tolerance less than 1×10 −9 Pa m 3 /s.