Radiation imager and protective apparatus therefore

The X-Y-addressed solid state radiation imager protected from static charge build-up during periods of operation and non-operation, has a photosensor array comprising address lines disposed in respective rows and columns. A number of radiation sensitive elements are disposed in a matrix arrangement and coupled to respective ones address lines, and a common electrode structure is disposed over the address lines and the radiation sensitive elements to be electrically insulated from the address lines and coupled to the radiation sensitive elements. A ground ring is disposed around the periphery of the matrix arrangement of the radiation sensitive elements. A coupling circuit is electrically coupled between the ground conductor and the common electrode so as to provide an electrical connection to selectively equilibrate voltage potential between the common electrode and the ground ring. The coupling circuit comprises a resistive element having a resistance greater than about 104 Ohms. The coupling circuit comprises at least two field effect transistors, or a pair of opposite polarity connected field effect transistors coupled in parallel between the ground ring and the common electrode.