Patent ID: 7456409

Claim:
A low noise electronic data capture and read-out system for digital radiography comprising: a two dimensional array of discrete X-ray detection pixel sites, each pixel site having (a) a capacitor and a capacitor discharge circuit and a comparator circuit, the discharge circuit including a controlled solid state switch and a constant current source, the switch serving to isolate the storage capacitor when the switch is open, the constant current source serving to discharge the storage capacitor at a controlled rate when the switch is closed, the comparator circuit outputting a signal representing an end-of-discharge time for the capacitor, and (b) a stored charge-to-time conversion circuit responsive to the output signal from the comparator for converting the X-ray fluence proportional charge on the capacitor to a corresponding digital data value; and read-out electronics for arranging and transferring said digital data from each of the pixel sites to a data storage medium in an ordered data matrix representing a two dimensional image of X-ray fluence on the array of pixel sites.