OPTICAL READER

PURPOSE:To read information accurately and improve the throughput, by controlling the light storage time of an image sensor is accordance with the density of read characters, symbols, etc. CONSTITUTION:A PCS value detecting circuit 25 monitors the output signal of an image sensor 23 which is converted in accordance with the variance of the PCS value (density of characters, symbols, etc.) of an object to be read. When the detecting circuit 25 detects that the output of the sensor 23 is lowe than a reference level, the detecting circuit 25 operates a timing generating circuit 21 to extend the light storage time of the sensor 23, and the output level of the sensor 23 is controlled to keep a certain level. When the output of the sensor 23 is higher than the reference level, the detecting circuit 25 does not operate the timing generating circuit 21. Thus, information is read accuratelly independently of the variance of the PCS of the object to be read, and the throughput is improved.