Image forming apparatus and method

摘要

An image forming apparatus reduces superimposing misalignment due to skew difference and registration difference and superimposing misalignment of visible image due to periodic position error generated on a plurality of latent image carriers respectively by correcting image information. A controller of the image forming apparatus has a deviation amount storing unit store data of magnification error in the sub-scanning direction e, executes rotation posture determining process that sets writing rotation posture as rotation angle posture at the time of starting writing latent image on photoconductors for Y, M, C, and K respectively, and has an image data correcting unit correct the image information based on the determined writing rotation posture and various error data (including magnification error in the sub-scanning direction e).

主权项

1. An image forming apparatus, comprising:
an image information acquiring unit to acquire image information; a plurality of latent image carriers to carry latent images on their rotating surfaces; a latent image writing unit to write latent images on the plurality of latent image carriers, respectively; a plurality of developing units to develop latent images on the plurality of latent image carriers, respectively; an endless moving member to move its surface endlessly to go through opposite positions against the plurality of latent image carriers sequentially; a transferring unit to transfer developed visible images on the plurality of latent image carriers respectively to a recording sheet either after superimposing the visible images on the surface of the endless moving member or on the recording sheet held on the surface of the endless moving member; a data storing unit to store deviation amount data that indicates superimposing deviation of visible images on the surface of the endless moving member or the recording sheet; an image detecting unit to detect an image formed on the surface of the endless moving member; and a controller to execute a latent image writing process on the plurality of latent image carriers, respectively, by controlling driving of the latent image writing unit based on corrected image information after executing an image information correcting process that corrects image information acquired by the image information acquiring unit based on the deviation amount data stored in the data storing unit to reduce superimposing deviation of latent images written on the plurality of latent image carriers, respectively, to write latent images, to obtain misalignment detecting pattern images by transferring predefined position detecting images formed on the plurality of latent image carriers, respectively, to the surface of the endless moving member, and to update the deviation amount data stored in the data storing unit at a predefined timing based on a timing of detecting the position detecting images by the image detecting unit; wherein the controller has the data storing unit store periodic variation characteristic data that indicates variation characteristic of latent image writing position shift in the surface direction of movement of the latent image carrier generated at one round cycle of the latent image carrier at a predefined latent image writing position in the circumferential direction of the surface of the latent image carrier for each of the plurality of latent image carriers, execute a writing rotation posture determining process that sets a writing rotation posture as a rotation angle posture upon starting writing latent images on the plurality of latent image carriers, respectively, in the image information correcting process, and correct the image information based on the writing rotation posture determined for the plurality of latent image carriers, respectively, and the deviation amount data and the periodic variation characteristic data stored in the data storing unit.