Magnetic transmission mechanism and applications thereof

摘要

A transmission mechanism for converting a rotary movement into a translatory movement includes an internal and an external coupling member which have cooperating double thread systems made of a magnetizable material. The external coupling member includes a series of permanent magnets which are polarized in an axial direction and are provided at regular intervals between the individual threads of the thread system so that the individual threads each form a common pole shoe for the permanent magnets providing a maximum magnetic flux density along the portion of the thread system containing the permanent magnets. The presence of a non-magnetizable material between the threads provides that the mutually facing walls of the coupling members are smooth, and a static gas bearing can be applied between these walls. A suitable application of the transmission mechanism is in a positioning device which in turn is eminently suitable for use in an optical lithographic device for the manufacture of semiconductor substrates.