IMAGE FORMING DEVICE AND DETECTION OF ORIGINAL DENSITY IN IMAGE FORMING DEVICE

PROBLEM TO BE SOLVED: To provide an image forming device which is capable of lessening the inertia load acting on a document exposure lamp when copying is continuously executed with plural documents by using an automatic document feeder. SOLUTION: The automatic document feeder 20 successively feeds the plural documents 2 by one sheet each and set the documents 2 in such a manner that the front ends of the documents 2 exist at a document stop position P1. An optical scanner 13 exposes the document 2 in order to detect a document density and reads the document 2 by scanning the document 2 while exposing the document. The optical scanner 13 stops at a density detection position P2 after reading the final document and ending the scanning relating to the document 2. When the automatic document feeder 20 transports the front end of the next document 2 to the document stop position P1, the optical scanner 13 exposes the next document 2 and a density sensor 12 detects the document density in accordance with the reflected light from the next document 2.