JPS56164363A - Illuminating device of variable magnification copying machine - Google Patents

Abstract

PURPOSE:To make correction of illuminance distribution easily in a longitudinal direction of a slit when magnification is varied by providing a plurality of electric lamps at focus point parts of an elliptical tube reflecting mirror located on a straight line in an interval with which a reduction of a light of a peripheral part of an optical lens can be compensated. CONSTITUTION:For example, in the illuminating device which is made to correspond with two steps of magnification, firstly when equal magnification, by an output of an equal magnification mode signal generating source 12, connection are made among terminals a-c of switching circuits 13-1 and 13-2 and voltage of a power source 11 is applied to a series circuit of halogen lamps A1- A6. In this instance, the lamps A1-A6 are symmetrical to an optical axis, further because of narrowness of an interval at an end part of an effective slit length D, luminous intensity at the end part becomes high. Secondly, in case of m times the magnification terminals b-c of the switching circuits 13-1 and 13-2 are connected, and voltage is applied to a series circuit of lamps B1-B<6>. In this case, the lamps B1-B6 are assymmetrical with respect to an optical axis and a lamp interval at one end part of the slit length D is narrow compared with the other end part, so, luminous intensity at the narrow side relatively becomes high. Thus with such constitution, the illuminance distribution can be easily corrected.