Distance sensor for determining a distance between two relatively movable members by measuring a time during which a measuring mark is in a light path between a light transmitter and a light receiver

Abstract

A distance sensor is provided for supplying a precise distance signal identifying the spacing between two components in a computed tomography apparatus which move relative to each other. The two components may be, for example, the rotating scan frame and the stationary gantry inside of which the scan frame rotates. The distance sensor includes a measuring mark mounted on one of the components and having a geometrical shape, such as the shape of a triangle tapering toward the other component, so that the measuring mark influences, such as by interrupting, the path of a measuring light ray which is emitted from the other of the components. The time during which the measuring mark influences the measuring light ray is dependent on the spacing of the components from each other. A signal indicative of this spacing is supplied to an evaluation circuit, and can be used to identify deviations from a specified rotational center of the scan frame with a high degree of resolution, so that appropriate correction steps can be undertaken.

Dependencies are inferred from the claim text.