Low noise lead screw positioner

Claim 2

A low noise positioning apparatus comprising: a lead screw having an axis extending in an axial direction; a nut lying about said screw; said screw and said nut having electrically conductive surfaces; means for flowing gas under pressure between said nut and said screw and in an axial direction and out of an end of said nut into the environment, and means for measuring the electrical resistance between said screw and said nut, whereby to enable checking for possible contact of the nut and screw.

Claim 3

A low noise positioning apparatus, comprising: a lead screw having an axis extending in an axial direction; a nut lying about said screw; a clearance space between said screw and said nut; said nut having at least 3 holes therein with the holes being circumferentially spaced about the screw to carry pressurized gas to the clearance space between the nut and screw; said holes each passing through a crest of a thread on said nut so as to discharge gas into the root of the thread on said screw which is complementary to said crest and; said holes being displaced slightly from each other in an axial direction with the spacing determined by the pitch of the thread on the nut such that each of the holes passes through the crest of the nut thread, whereby the nut is precisely supported in an orginal position in spaced relation with respect to the screw when a pressurized gas is passed through the holes in the nut into the clearance space between the nut and the screw with lateral displacement of the nut relative to the screw causing a pressure increase in the region where the spacing between the nut and screw is decreased with the pressure increase providing a restoring force to return the nut to its original position with respect to the screw.

Claim 4

A low noise positioning apparatus, comprising: a lead screw having an axis extending in an axial direction; a nut lying about said screw; a clearance space between said screw and said nut; said nut having at least 3 holes therein with the holes being circumferentially spaced about the screw to carry pressurized gas to the clearance space between the nut and screw; said holes each passing through a crest of a thread on said nut so as to discharge gas into the root of the thread on said screw which is complementary to said crest and; said holes being displaced slightly from each other in an axial direction with the spacing determined by the pitch of the thread on the nut such that each of the holes passes through the crest of the nut thread, whereby the nut is precisely supported in an orginal position in spaced relation with respect to the screw when a pressurized gas is passed through the holes in the nut into the clearance space between the nut and the screw with lateral displacement of the nut relative to the screw causing a pressure increase in the region where the spacing between the nut and screw is decreased with the pressure increase providing a restoring force to return the nut to its original position with respect to the screw.

Claim 5

The apparatus of claim 2 including: a plenum chamber within said nut which communicates with said holes such that a gas supplied to the plenum chamber flows through said holes into the clearance space between the nut and the screw.

Claim 6

The apparatus of claim 2 wherein: said nut includes at least a first and second group of holes with each group including at least 3 holes spaced circumferentially about the screw and passing through the crest of the nut thread into the root of the screw thread which is complementary to said crest; said groups of holes being spaced axially with respect to the screw such that gas passing through said groups of holes provides support for the nut in several regions which are spaced axially in correspondence with the spacing of the groups of holes, whereby the support for the nut when pressurized gas is passed through the groups of holes provides increased resistance to tilting of the nut with respect to the axis of the screw.

Claim 7

The apparatus of claim 2 wherein: the clearance space between said screw and said nut is on the order of 0.005 inches in permitting the free outflow of pressurized gas in the clearance space at a rate which is limited by the distance between the nut and the screw.