Array type x-ray detection apparatus

Abstract

In order to prevent destruction of a read gate by excessive storage of charge without any addition or change to the manufacturing process, the array type X-ray detection apparatus using a direct conversion system, which directly converts irradiation X-rays to charge, provides each pixel cell with a sensor section for converting X-rays to an amount of charge according to the amount of X-rays, a charge collecting electrode for storing the charge generated, a read gate for transferring the stored charge to an external read amplifier and a MIS diode using a TFT. A clamp signal is applied to one end of the MIS diode. The read gate and MIS diode are formed in the same manufacturing process. Since the amount of charge stored in the charge collecting electrode is clamped to the amount of charge corresponding to the clamp signal voltage by the MIS diode, the read gate is not destroyed even with excessive X-ray irradiation. Furthermore, instead of the MIS diode, a cutoff voltage control circuit and a cutoff gate using a TFT connected to the cutoff voltage control circuit are provided. When the output of the charge storage capacitor exceeds a cutoff voltage, the cutoff gate interrupts the inflow of charge to the charge storage capacitor to suppress further increase of output, thus preventing the read gate from being destroyed.