Patent ID: 7466464

Claim:
An image forming apparatus for adhering a toner to a photosensitive member to form a toner image, and transferring the toner image on the photosensitive member onto a transfer member supported by a transfer member supporting member which is included in a transfer apparatus and is provided in contact with the photosensitive member, said image forming apparatus comprising: a first storing portion which stores gradation pattern information in advance; a first pattern forming portion which reads the gradation pattern information from the first storing portion, forms a toner image according to the read gradation pattern information on the photosensitive member, and transfers the toner image onto the transfer member by the transfer apparatus; a first generating portion which reads an image according to the gradation pattern information on the transfer member formed by the pattern forming portion and generates a first gamma correction table on the basis of the read image information; a second pattern forming portion which reads the gradation pattern information, corrects the gradation pattern information according to the first gamma correction table generated by the first generating portion, forms a toner image corresponding to the corrected gradation pattern information, and transfers the toner image onto the transfer member supporting member; a second storing portion which detects density of the toner image transferred onto the transfer member supporting member by the first pattern forming portion and storing the detected density as a reference value of density; a third pattern forming portion which reads the gradation pattern information at an arbitrary timing, corrects the gradation pattern information by the first gamma correction table which the first generating portion generated, forms a toner image according to the corrected gradation pattern information, and transfers the toner image onto the transfer member supporting member; a calculating portion which detects density of the toner image transferred onto the transfer member supporting member by the third pattern forming portion, and compares the detected density with the reference value of density stored in the first storing portion to determine a density deviation; a second generating portion which generates a second gamma correction table on the basis of the density deviation which the calculating portion has calculated; and an image forming portion which reads an original image using the scanner, corrects the read image information with the second gamma correction table formed by the second generating portion, forms a toner image based on the corrected image information on the photosensitive member, and transfers the toner image onto the transfer member by the transfer apparatus.