| 摘要 |
PURPOSE:To optimally control illumination time by a method wherein time from starting of photoelectric conversion of a photoelectric conversion element to termination of illumination of a light emitting element is made variable so that the amount of light beam entering the photoelectric conversion element is controlled. CONSTITUTION:Light emitted from a semiconductor laser 101 driven by an LD driver 102 is received by an accumulation-type line sensor 104 via an optical system 103. Then the output of the sensor 104 is processed by a signal processor 106 to have the center of gravity, etc. of a beam having positional information calculated. Frequency of a line sensor driver 105 which specifies accumulation time, etc. of the driver 102 and the sensor 104 is counted by a timing circuit 107. Further, time of lighting and extinguishing of illumination of the laser 101 is controlled by the circuit 107. The efficient amount of the beam entering the sensor 104 can be therefore controlled to an optimal value. |
