Patent ID: 7667861

Claim:
An image forming apparatus comprising: a plurality of image data acquisition units for respectively acquiring one or more page(s) of image data; a color or monochrome determining unit for determining whether each of the acquired pages is in color or in monochrome; an image forming unit for performing image formation of each page switchably using a monochrome-only image forming function for a monochrome page or a color and monochrome image forming function for a color page and a monochrome page; an image data switching unit for sequentially selecting and arranging the acquired pages of image data one by one so that the image formation of each page is performed in the order of selection; a function selecting unit for selecting either one of the monochrome-only and color and monochrome image forming functions for each of the arranged pages on the basis of the determination result made by the color or monochrome determining unit; and a control unit for controlling the image forming unit so that image formation of each page is performed using the selected image forming function; a processing time memory unit for storing in advance time required for switching the image forming functions, time required for image formation of a monochrome page using the monochrome-only image forming function and time required for image formation of a monochrome page using the color and monochrome image forming function; and a movement distance memory unit for storing in advance a traveling distance of a photoconductor during switching between the image forming functions, a traveling distance of the photoconductor during the image formation of a monochrome page using the monochrome-only image forming function and a traveling distance of the photoconductor during the image formation of a monochrome page using the color and monochrome image forming function, wherein the image forming unit is of an electrophotographic type, wherein the function selecting unit comprises a selection condition switching unit for switching between a first selection mode and a second selection mode, when the one or more pages of image data include two color pages and one or more monochrome page(s) therebetween, wherein the first selection mode selecting either one of the image forming functions on the basis of the number of monochrome page(s) and the time required for switching and the respective image formation in the processing time memory unit so that quicker image formation of the monochrome page(s) is performed, and wherein the second selection mode selecting either one of the image forming functions on the basis of the number of the monochrome page(s) and the traveling distances stored in the movement distance memory unit so that image formation of the monochrome page(s) is performed with a shorter traveling distance of the photoconductor.