Patent ID: 7251423

Claim:
An image forming apparatus comprising: an image carrier which is structured so as to be able to carry an electrostatic latent image on a surface of said image carrier; a toner carrier which rotates in a predetermined direction while carrying toner and accordingly transports said toner to an opposed position facing said image carrier; and image forming means which applies a predetermined developing bias upon said toner carrier, causes said toner carried by said toner carrier to move to said image carrier, visualizes said electrostatic latent image with said toner, and accordingly forms a toner image, characterized in that said image forming means executes optimization during which a toner image is formed as a patch image and density control factors influencing an image density are optimized based on a image density of said patch image, and that prior to formation of said patch image, idling of said toner carrier is executed which requires rotation of said toner carrier by at least one revolution, said image forming apparatus further comprising: light emitting means which irradiates light toward a patch image area of said surface of said image carrier in which said patch image is formed; and light amount detecting means which detects a light amount reflected from said patch image area, characterized in that said light amount detecting means detects the light amount reflected from said patch image area without carrying toner and the light amount reflected from said patch image area when carrying said patch image, and said patch image density is calculated based on the result of the detection, wherein while said toner carrier is idling, a preceding process is executed which requires to detect the light amount from said patch image area as it does not carry toner.