Abstract: The image formation apparatus satisfies a user's demand to effectively use a sheet by writing an image to the marginal sheet edge, and prevents that toner is not transferred to the sheet but adhered to a transfer roller when the sheet is slightly misregistered from its accurate position, whereby back stain occurs in a next sheet. In this apparatus, an area in which the image is masked is changed by a CPU, according to an input mode of a image signal from an image signal generation unit. In a printer mode that the image signal is input from a host computer, image masking signals by which an image can be formed up to the sheet edge are given to gate circuits so as to expand the image up to the marginal sheet edge. In a mode that the image signal is input from an image reader, the image masking signals by which a margin can be provided at the sheet edge are given to the gate circuits so as to limit an image area.

Abstract: A toner remaining amount detecting device used for an electrophotographic image forming apparatus to sequentially detect an amount of toner in a toner containing portion, includes a first electrode disposed along a path in which an amount of toner contained in the toner containing portion for containing the toner is decreased upon consumption, a second electrode disposed so that the toner in the toner containing portion can exist between the first and second electrodes when the toner is contained in the toner containing portion, and a capacitance-detecting device for sequentially detecting a change in capacitance between the first and second electrodes, wherein the amount of the toner in the toner containing portion is detected sequentially.