Abstract: A toner image transferring device is applied to, for example, an electrophotographic printer for electrostatically transferring a charged toner image from a photosensitive drum to a sheet or paper. The device encompasses a transfer charger disposed near the drum to form a clearance therebetween for feeding an electric charge to the sheet or paper through which the sheet or paper is passed, an electric source for supplying an electric energy to the transfer charger to give the sheet or paper an electric charge having a polarity opposite to that of the charge of the toner image, and a controller for controlling the electric energy output from the electric source the transfer charger so that a leading edge of the sheet or paper can be prevented from being excessively charged.

Abstract: A method of detecting toner in the toner supplying unit of a developing unit wherein a toner supplying roller is caused to make a single turn, the duration of a signal indicating "no-existence of toner" issued during this single turn period is accumulated by timer function of a control unit. When a total sum of accumulated signal timer duration is longer than a first preset time, including a constant margin added to the difference between the time required for a single turn of the toner supplying roller and the time required for passing over the toner detecting surface by a cleaning means, the "no-existence of toner" condition is detected for the toner supplying unit.

Abstract: A developing device includes a developing agent holding vessel; and a developing roller having a rotating non-magnetic sleeve and a magnetic roller which is surrounded by the sleeve and has magnetic poles. A blade is disposed at an outlet of the vessel and a stirring roller stirs the developing agent which includes a toner and a carrier in the vessel. The developing roller is provided with a moving mechanism for shifting the position of the magnetic pole of the magnetic roller, wherein one of the magnetic poles is facing a surface of a photosensitive drum during normal use of the developing agent, and no magnetic pole faces the photosensitive surface during a replacement of the developing agent.