| 摘要 |
PURPOSE:To obtain a correct detecting value even when the density is shifted in the width direction of an original by providing a photodetecting window whose central part is narrow but becomes gradually winder as it goes to the end part and providing a hood to regulate the photodetecting scope of a photodetecting element. CONSTITUTION:The output value of a photodetecting element 43 is gradually reduced as the directional angle is increased. To correct the output of the photodetecting element 43 having such a directional characteristic, the opening degree in the vertical direction of a photodetecting window 41 is made to become larger as it goes to the end part. Thus, after the irregular reflection is executed directly from an original surface 27 or in a copying machine 1, the disturbance light to arrive at a luminous energy detecting device 40 is interrupted by a hood 42, only the reflecting light to arrive through respective mirrors 22, 23 and 24 passes through the photodetecting window 41, and is photodetected by the photodetecting element 43 in the condition being corrected by matching with the directivity of the photodetecting element 43. |
