IMAGE FORMING APPARATUS AND METHOD FOR DETECTING HOME-POSITION ERROR

摘要

An image forming apparatus and a method for deciding a home-position error are provided to detect occurrence of the home position error whenever each color is developed by having an indicating element including indicating units of different sizes, thereby improving reliability of an image. An image forming apparatus comprises the followings: a plurality of developing units; a cam shaft(120); a plurality of cams installed on the cam shaft so as to respectively correspond to the plurality of developing units; and a power transmitting unit which is installed between the plurality of developing units and the plurality of cams and selectively transmits a rotational force of a driving source to the plurality of developing units according to a rotational phase of the cam shaft. The image forming apparatus further comprises the followings: an indicating element(132) which is installed on the cam shaft and has a plurality of indicating units; and a sensor(140) for detecting the plurality of indicating units. The sensor decides whether a home position error is generated whenever each of the plurality of indicating units passes through the sensor.