Rotary flexure bearing

摘要

This rotary flexure bearing consists of concentric inner and outer hubs connected by compound flexure stages. These compound flexure stages provide the angular compliance required for bearing rotation as well as compliance for flexure foreshortening while holding a constant axis of rotation over the entire range of motion. This design offers large angular displacement, low operating stress, low operating torque, and high stiffness in the five noncompliant degrees of freedom. The rotary flexure bearing described herein has applications in precision mechanics, particularly opto-mechanics. Specific applications include but are not limited to wafer and reticle alignment stages used in microlithography systems, mirror pointing and scanning mechanisms used in tactical and spaceborne systems, as well as flip-in mechanisms used in multiple field of view optical systems.

主权项

1. A rotary flexure bearing, comprising:
an inner hub having a substantially cylindrical core which has a clear and unobstructed hole passing through the entire length of said substantially cylindrical core and a plurality of essentially equal length radial spokes fixed to said substantially cylindrical core which extend radially outward from the outer surface of said substantially cylindrical core; an outer hub having a substantially cylindrical interior that is greater in diameter than the major diameter of said plurality of spokes on said inner hub and having the major axis of said substantially cylindrical interior aligned coaxially with the major axis of said substantially cylindrical core of said inner hub; a compound flexure stage which connects the outermost end of adjacent said spokes on said inner hub to the substantially cylindrical interior of said outer hub comprising a first stage having exactly two essentially identical first stage flexure members having the outermost end of each said first stage flexure members fixed to said substantially cylindrical interior of said outer hub and the innermost end of each said first stage flexure members fixed to a circular segment member located on a radius greater than the major radius of said inner hub cylindrical core and less than the radius of said outer hub cylindrical interior, and a second stage having exactly two second stage flexure members which are essentially identical to said first stage flexure members with the outermost end of each said second stage flexure member fixed to the outermost end of said adjacent spokes on said inner hub and the innermost end of each said second stage flexure member fixed to said circular segment member to which the innermost end of each said first stage flexure member is also fixed; wherein the two first stage flexure members and two second stage flexure members are each formed as a blade having a thick width and a thin length, each blade being oriented such that the thin length is perpendicular to the major axis of said substantially cylindrical core of said inner hub, while the thick width is parallel to the major axis of said substantially cylindrical core of said inner hub; and wherein each flexure member blade is flexible along the thin length between the innermost end and outermost end into an “S” shape, such that the inner hub and outer hub are capable of axial rotation with respect to one another.