Patent ID: 7211803
Filing Date: 2007-05-01
Classification: G01T

Abstract:
1. A wireless X-ray detector for a digital radiography system, comprising: a sensor panel of amorphous or crystalline silicon photodiodes or metal insulated semiconductor photodiodes and having a plurality of pixels arrayed in a matrix of rows and columns, each pixel having a photodiode, a charge capacitor for collecting charge from the photodiode during X-ray exposure and a pixel switch; a pixel output amplifier defining a source of virtual ground, the pixel switch selectively coupling the photodiode and charge capacitor of all of the pixels to the source of virtual ground; a bias supply circuit coupled to all the sensor panel pixels holding the photodiodes in a reverse biased state during the absence of X-ray exposure; a control circuit responsive to the detection circuit for holding the pixel switches closed during absence of X-ray exposure and for opening substantially all the pixel switches upon detecting onset of X-ray exposure thereby disconnecting the pixel from the source of virtual ground so as to allow charge collection in the pixel capacitors; and an X-ray presence detection circuit responsive to a change in current flow in the bias supply circuit for indicating onset and cessation of X-ray exposure on the pixels.