| 摘要 |
PURPOSE:To control correctly an automatic regulation function for image density even in the stage of copying of enlargement, reduction and color originals by comparing the detected output of the original image density with a reference voltage and controlling an exposing lamp voltage according to the result of the comparison. CONSTITUTION:The reflected light from a toner image is converted to a voltage by a phototransistor 17 and a variable resistor VR1 and is conducted to comparators 23 and 24. The voltage is compared with reference voltages V1, V2 preset by the variable resistor VR1 and VR2. The outputs Q1, Q2 of two RS-FF29, 30 rise both to a high level when the original image density is low and the voltage V proportional to the quantity of the refelected light from the toner image is V>V1. Q1 is the low level and Q2 is the high level at such original density at which the voltages are V1>V>V2. Both Q1 and Q2 are the low level when the original image density is high and V>V2. The exposing lamp voltage is changed in the succeeding stage circuit by utilizing said signal, by which the copy image picture having no ground stain is obtd. from the exposing lamp voltage meeting the original image density even in the copying of the color original or the copying in enlargement or reduction. |
