Image read-out apparatus employing a photomultiplier

摘要

An image read-out apparatus for exposing a recording medium carrying an image stored therein to a light beam, and photoelectrically detecting light carrying the image information obtained from the recording medium by use of a photomultiplier comprises a comparator for comparing an output current signal of the photomultiplier with a predetermined reference value, and a voltage detector for detecting the voltage generated at a bleeder resistor of the photomultiplier. The apparatus also comprises a selection circuit for receiving the output current signal of the photomultiplier, a voltage signal detected by the voltage detector, and an output of the comparator, selecting the output current signal of the photomultiplier when the output current signal of the photomultiplier is equal to or lower than the reference value, and selecting the voltage signal when the output current signal of the photomultiplier is higher than the reference value.