Ferro device for the automatic control of x-y displacements in x-ray examination

Claim 1

In an apparatus for controlling the movement of an x-ray radiating assembly which includes an x-ray source and a film cassette which are arranged to be displaceable in relatively opposite directions and are adapted to swing about a pivotal axis for making radiographs of plane body sections, wherein an x-ray passing through any point to be radiographed will always strike the same point at the film, the apparatus further including a control assembly comprising, a rotatable platform, first means for rotating said platform, a guide member carried and rotated by the platform and movable longitudinally on said platform, the guide member adapted to displace said x-ray tube and film cassette according to a predetermined cyCle including rotational and longitudinal movement, second means for driving said guide member in longitudinal movement on said platform, a first potentiometer on said platform engaged and driven by said guide member for converting each position of said guide member into a first electrical signal corresponding to its movement, a rotatable cam-coding member carried by the assembly, this cam having a cam-shape to provide said predetermined cycle of movement, means for rotating the cam, a cam follower driveable in longitudinal movement by said cam, a second potentiometer driven by said follower for converting displacement of the follower into a second electric signal having magnitude corresponding to the cam-shape and to the distance the guide member is to move, third means for comparing the first signal with the second signal and producing the profile signal corresponding to the difference between said signals, said control signal being communicated to said second means to move said guide member longitudinally until the first and second signals are equal and there is no difference between these signals.