Image sensor capable of producing an image signal free from an afterimage

摘要

Charges photoelectrically generated in reversely biased photodiodes are sequentially transferred through respective thin-film transistors to a driver IC. A plurality of capacitors are connected to the anodes of the respective photodiodes. During a charge reading period, a variable voltage generation circuit supplies the cathode of each photodiode with a first voltage that is higher than an anode voltage to reversely bias the photodiode. During a predetermined period after the charge reading period, the variable voltage generation circuit supplies the cathode of the photodiode with a second voltage that is lower than the first voltage and a gate pulse generation circuit supplies, through the associated capacitor, the anode of the photodiode with a third voltage that allows the photodiode to be forwardly biased.