CONTROL OF EXPOSURE LIGHT INTENSITY

PURPOSE:To enable the light intensity control including measurement of light intensity to be performed completely automatically by providing a light-intensity controlling circuit, which maintains the light intensity constant by means of a light receiving equipment fixed near a light source, providing a movable light receiving part at an exposed part, and feeding back the measured result of the light intensity to a control circuit. CONSTITUTION:Light receiving equipments 5 and 6 are installed near a light source 1, and in the position at which a panel 4 used as an exposed part is situated. The light receiving equipment 5 is fixed, while the light receiving equipment 6 is attached to a rotary arm 7 of an air cylinder so that the equipment 6 is horizontally movable according to the rotational movement of the arm 7. For the purpose of controlling the luminous energy of the light source 1 according to the result of measurement performed with the light receiving equipment 5, a light-intensity controlling circuit consisting of an amplifying circuit 8, an analog computing circuit 9, an SCR10 and a leakage transformer 11 is installed. In addition, for the purpose of feeding back the measured result obtained with the light receiving part 6 to such a light-intensity controlling circuit, an arithmetic unit 12, an amplifier 13 and the like are provided.