Image forming apparatus with color change area discriminating function

Claim 1

An image forming apparatus with a color change area discriminating function, said apparatus comprising: an original table on which a light-transmitting original is placed; transmission light emitting means, provided movable along said original table, for emitting transmission light through the original placed on said original table; color change area designating means for shifting the light emitted from said transmission light emitting means to an arbitrary area of an original image which is to be subjected to a change in color of image formation to designate the arbitrary area as a portion to be subjected to a change in color of image formation prior to an image formation operation; color change area storage means for storing first position data representing the area to be subjected to a change in color of image formation and second position data representing a remaining area excluding the area to be subjected to a change in color of image formation, in response to designation by said color change area designating means; original scanning means, arranged to optically scan the original placed on said original table, for producing an optical image of the original upon completion of scanning of the original; image forming means for focusing the optical image of the original which is scanned by said original scanning means and selectively driving first and second developing units respectively containing first and second color agents corresponding to at least basic and change colors, thereby forming an image on an image forming medium with predetermined colors; image erasing means arranged to selectively erase an image to be formed by said image forming means; image forming medium returning means arranged to selectively return the image forming medium with the image formed by said image forming means to said image forming means; color change area display means, having a display element capable of displaying a pattern, for flashing a display pattern corresponding to the area to be subjected to a change in color of image formation and designated by said change color area designating means, the display pattern being included in a display pattern corresponding to the original; first control means for supplying a drive signal to said first developing unit in said image forming means during first image formation operation, reading out from said color change area storage means the first position data representing the area to be subjected to a change in color of image formation and supplying the readout data as an erasure signal to said image erasing means, and supplying a return instruction signal to said image forming medium returning means; and second control means for supplying a drive signal to said second developing unit in said image forming means during second image formation operation, reading out from said color change area storage means the second position data representing the area excluding the area to be subjected to a change in color of image formation, and supplying the readout data as an erasure signal to said image erasing means.