Patent Number: 045286850
Section: abstract

A device for linearly oscillating one or more of a plurality of X-ray filter elements singly or in combination in and out of an X-ray beam at television frame rates. First and second substantially coplanar filter elements are adjacent each other and formed as a unitary member that is transverse to the X-ray beam. It is slidable bidirectionally on parallel guide tracks in one plane. A servo motor drives a closed loop belt which attaches to said member. A third planar filter element runs on tracks in a plane parallel to that of the unitary member. There are lug means on the third element spaced apart in the direction of its travel member that project up and are between the lug means on the third element to enable pushing or pulling it. Thus, the first and second filter elements can be oscillated alternately in and out of the X-ray beam by moving said unitary member without engaging the third element so it stays out of the beam. The member can be driven to one travel limit to pull the third element into the beam and let it stay there while the first element is oscillated beneath it so the beam passes through two filters. And the member can be driven to one travel limit and not be oscillated so the third filter element stays in the beam.