Inventors:
Gregory D. Schwehr - Milwaukee WI
Richard T. Brandt - New Berlin WI
James J. Kandler - Milwaukee WI
Assignee:
General Electric Company - Milwaukee WI
International Classification:
G05B 1928
H01J 3720
Abstract:
An X-ray table having an elevator mounted on a base for vertical movement, an intermediate support mounted on the elevator for moving longitudinally, and a carriage with a patient cradle on it for moving longitudinally on the support. A pair of gas springs mounted at the forward end of the table provides a constant upward force to compensate for weight of the elevator and the cantilevered load which is exerted as the patient cradle is extended in the longitudinal direction. There are individual servomotors for driving the support and the cradle. The intermediate support drive includes a drive bar and switch assemblies for sensing any force of more than 25 lbs. , for example, exerted on the patient or patient cradle and for disengaging the servodrives in response thereto. The cradle drive incorporates a zero-backlash longitudinal friction drive which includes a harmonic drive unit to achieve accurate positioning of the patient. An encoder is driven by a closed-loop cable attached to the patient cradle to accurately indicate its position and speed even though there is a two-stage drive.