Photoconversion device having reset control circuitry

摘要

A photoconversion device comprises plurality of cells 1 each having a bipolar type sensor element T, the base of which is connected to a reset switch FET M and is also capacitively coupled to a control electrode. The device is read out by providing a positive pulse to the base of the sensor T through the control electrode, and is refreshed by a first operation in which the base is set to a preset level through the FET M and a second operation in which the base-emitter junction of the sensor T is forward biased. A control terminal 19 provides a high level reset voltage to a main electrode region of the FET M through an emitter follower arrangement 18 to turn the FET M on for the first reset operation without providing a negative pulse on the horizontal drive line 2 which is connected both to the gate of the FET M and the capacitively coupled control electrode. This permits a relatively high voltage read out signal to be provided on the horizontal drive line 2 without subjecting the line to an excessive total voltage swing.