Patent ID: 7539426
Filing Date: 2009-05-26
Classification: G03G

Abstract:
1. An image forming apparatus comprising: an image carrier on which an electrostatic latent image is formed; a rotary developing device having N developer carriers, where N defines a total number of developer carriers, on a rotation orbit, the N developer carriers carrying developers to develop the electrostatic latent image, and the rotary developing device moves in turn the N developer carriers to a development position opposite to the image carrier; and a toner concentration sensor that measures toner concentrations of the developers carried in the developer carriers, a measurement position of the toner concentration sensor is set on a second virtual straight line, the second virtual straight line having a first angle toward a first virtual straight line in an opposite direction to a rotation direction of the rotary device, the first virtual straight line connecting a rotation center of the rotary developing device and the development position, and the N developer carriers are placed in turn in an order starting from a first developer carrier to an N-th developer carrier at the same angular interval as the first angle in the opposite direction to the rotation direction of the rotary developing device, and an angular interval between the N-th developer carrier and the first developer carrier is set to a second angle greater than the first angle.