Image forming apparatuses employing an electrophotographic method

An image forming apparatus, comprising:

• a first photoreceptor;
• first exposure means configured to expose the first photoreceptor so as to form an electrostatic latent image on the first photoreceptor;
• first developing means configured to develop the electrostatic latent image formed on the first photoreceptor as a toner image;
• a second photoreceptor;
• second exposure means configured to expose the second photoreceptor so as to form an electrostatic latent image on the second photoreceptor;
• second developing means configured to develop the electrostatic latent image formed on the second photoreceptor as a toner image;
• an intermediate transfer belt onto which the toner image formed on the first photoreceptor and the toner image formed on the second photoreceptor are transferred;
• a secondary transfer roller configured to transfer the toner image on the intermediate transfer belt onto a sheet;
• a plurality of sheet accommodation units configured to accommodate sheets;
• detection means configured to detect a sheet and provided for individual sheet accommodation units;
• and
• control means configured to continue an image forming job by performing switching to a second sheet accommodation unit which accommodates sheets which are the same as a specified type of sheet accommodated in a first sheet accommodation unit, which is one of the sheet accommodation units, when it is determined that the first sheet accommodation unit does not accommodate a sheet in accordance with a signal supplied from the detection means provided for the first sheet accommodation unit while the image forming job of forming an image on a sheet supplied from the first sheet accommodation unit is executed,
• wherein the first photoreceptor is disposed on an upstream side relative to the second photoreceptor in a direction of rotation of the intermediate transfer belt, and
• the control means executes a cleaning process of forming an electric field for cleaning between the intermediate transfer belt and the secondary transfer roller when determining that a sheet to which a toner image of image data is to be transferred is not accommodated in the first sheet accommodation unit after formation of an electrostatic latent image of data in a certain page is started by the first exposure means, and causes the first exposure means to form the electrostatic latent image of the image data on the same page before the cleaning process is terminated.