Patent ID: 8385761

Claim:
An image forming apparatus, comprising: an image bearing member to bear a toner image and a toner pattern for detection of toner degradation on a surface thereof; a toner image forming device to form the toner image and the toner pattern on the image bearing member; an intermediate transfer member facing the image bearing member, on which the toner image and the toner pattern are transferred from the image bearing member; a primary transfer device to transfer the toner image from the image bearing member onto the intermediate transfer member, and transfer the toner pattern from the image bearing member to the intermediate transfer member using transfer conditions that deliberately reduce transfer efficiency compared with transfer efficiency at image formation; a toner adherence detector to detect an amount of toner adhered to the toner pattern transferred from the image bearing member onto the intermediate transfer member at multiple places; a secondary transfer device to transfer the toner image from the intermediate transfer member onto a recording medium; and a controller including a read only memory (ROM), a random access memory (RAM), and a CPU to adjust one or more toner image forming conditions of the toner image forming device to adhere a proper amount of toner to the toner image formed on the image bearing member, the controller calculating a degree of degradation of toner based on a difference in the amount of toner adhered to the toner pattern formed on the intermediate transfer member detected by the toner adherence detector at multiple places and adjusting a secondary transfer condition for the secondary transfer device based on the calculated degradation of toner adhered to the toner pattern, wherein the toner adherence detector is an optical detector that detects at multiple places the amount of toner adhered to the toner pattern on the intermediate transfer member based on a specular reflection light output data Reg reflected by the toner pattern when using black toner, and wherein the degree of degradation of toner is obtained using a degree of granularity D_Gran obtained by D_Gran=α×(Reg_max−Reg_min), where Reg_max is a maximum value of the specular reflection light output data, Reg_min is a minimum value thereof, and α is a coefficient of determination of the degraded toner inherent to the image forming apparatus.