| 摘要 |
PURPOSE:To perform the uniform exposure of an original surface or exposed surface, by controlling the luminous intensity of a light source by calculating the irregularity of initial exposure in the process of exposure by a photoelectric converter which detects illuminance. CONSTITUTION:Four light sources having discharge tubes 3 fitted at focal points of reflectors 4 are provided with electromagnets 5 which vary relative positions between arcs of the discharge tubes 3 and the reflectors 4. In the exposure area 2b of contact glass 2, a photoelectric converter 11 detecting illuminance is fitted. In this constitution, the moment the emitted energy of the discharge tube is triggered, it increases suddenly and decreases later, so the photoelectric converter 11 calculates the exposure up to time (t1). Then, a prescribed electric circuit stores previously the total quantity of light of the discharge tubes and the current of an exciting coil 6 is controlled on the basis of the stored value and initial exposure to equalize the total exposure, thus correcting the luminous intensity of the light sources. Consequently, exposure over the entire original surface is performed uniformly. |
