Ionography imaging chamber for variable distance X-ray source

Claim 1

In an imaging chamber for an X-ray system having first and second substantially planar electrodes of low conductivity material, means for mounting said electrodes in the chamber in spaced relation defining a gap therebetween for an imaging medium responsive to incoming radiation, means for connecting a power supply to the center of said first electrode and to the periphery of said second electrode, and a first resistance connected between the periphery of said first electrode and the center of said second electrode completing a current path across the power supply to produce an electrostatic field in the gap, with the conductivity per unit area of each of said electrodes varying from a central zone to said peripheries such that the electrostatic potential at the gap surfaces of the electrodes approximates the electrostatic potential for concentric spherical metal electrodes, the improvement comprising a second resistance electrically connected in parallel between the center and periphery of one of said electrodes for producing different currents in said first and second electrodes and thereby compensate for movement of an X-ray source relative to said chamber.