| 摘要 |
PURPOSE:To perform invariably stable photoelectric conversion by suppressing the amplitude of an output electric signal of a photoelectric converting circuit to a constant level without reference to fluctuation of the output intensity of a light source by an optical character reader. CONSTITUTION:Subject 22 is lightened up by light source 21 and reflected light from subject 22 is changed in optical path by reflex mirror 23 to form its image on line sensor 25 via lens 24. Then, charged accumulated on sensor 25 are read out successively with timing signal 260 generated by control circuit 26 and inputted to automatic gain control 27. Direct light from light source 21, on the other hand, is converted into an electric signal by photodetection part 28 including photoelectric converting elements and the signal is integrated 29 with timing signal 261 from control circuit 26. According to timing signal 262 from circuit 26, said control 27 is brought under gain control with the output of circuit 29, and corrected electric signal 210 is outputted from terminal 211. Thus, invariably stable photoelectric conversion is carried out. |
