Copying machine with capacity to measure transparency of original

摘要

A copying machine of the present invention measures light transmittance of a document so as to adjust copying concentration on the basis of the measured result. The copying concentration is concretely adjusted by adjusting electrification voltage of a photosensitive body, and/or developing bias voltage, and/or quantity of exposure light. The copying machine is free from the occurrence of back image copying when a document is double-faced. A copying machine of the present invention further comprises means for discriminating whether the document is a double-faced one or a single-faced one.