Photoelectric sensor for document copier

摘要

A solid state photoelectric copier comprises an array of photoelectric converter elements, or photodiodes (D11-Dni) associated with charge storage capacitors (C11-Cni). The received light is converted into a proportional charge. Associated with diode and capacitor are switches (S11-Sni) of analog type, connected between the diode and a shift register (SR). The other end of the diode is connected to a circuit (A1-An) for transferring the quantity charge as a signal. The shift register switches to read out the charges in sequence.The photodiode and associated capacitor are made as a single unit using amorphous silicon photoconductive material. The capacitance of the charge accumulator (C11-Cni) can be made much larger than the parasitic capacitance of the switches (S11-Sni)