Ricoh Company, Ltd.

Harumi Takahashi

Yoshihiro Ogata

Koji Sakamoto

Koji Hirakura

Yoshihiro Abe

An image forming apparatus includes a mechanism for detecting whether or not a detachably loaded maintenance unit is a genuine unit. A holding part holds the maintenance unit in a predetermined position by applying a predetermined pressure on the maintenance unit. A first engaging part is formed on a genuine maintenance unit, and a second engaging part is formed on the holding part. This second engaging part has a pressure conductive material provided thereon, and the first and second engaging parts have shapes such that one fits into the other when the genuine maintenance unit is in the predetermined position. A detecting part detects whether or not the genuine maintenance unit is in the predetermined position by detecting a change in a resistance of the pressure conductive material.

Image forming apparatus having means for detecting loaded unit

A device for detecting a momentary cutoff of an AC power source which is used with a data processing apparatus or the like. The device determines that a momentary cutoff has occurred in the AC power source when an actual rotation speed of a motor energized by the AC power source for rotation is lower than a predetermined rotation speed.

Device for detecting momentary cutoff of AC power source

An improved copy paper separating device for use in a transfer type electrophotographic copying machine is provided. The separating device includes a conductive carrier member, preferably in the form of a conductive endless belt extended between a pair of pulleys. The conductive carrier member is disposed in the periphery of the photosensitive member to which a copy paper is brought into contact for the transfer of a toner image formed on the photosensitive member. The potential of the conductive carrier member is maintained nearly at zero level during the first step of the separating operation; whereas, the potential of the carrier member is increased to a predetermined value of the polarity opposite to that of the toner image during the second step. Information as to the conditions of separating operation is also supplied and the timing of changing potentials is appropriately adjusted. Moreover, a plurality of voltage sources having different potential levels are provided and the potential is selectively applied to the carrier member as required, which is particularly useful when applied to a duplex copying machine.

Transfer medium separating device

In a copy paper separating device for use in a transfer type electrophotographic copying machine which includes a conductive carrier member, preferably in the form a conductive endless belt extended between a pair of pulleys. The conductive carrier member is disposed in the periphery of the photosensitive member to which a copy paper is brought into contact for the transfer of a toner image formed on the photosensitive member. The potential of the conductive carrier member is maintained nearly at zero level during the first step of the separating operation; whereas, the potential of the carrier member is increased to a predetermined value of the polarity opposite to that of the toner image during the second step.

A toner image of an original document is formed on a photoconductive drum (1) and transferred onto a copy sheet (4) which is moved into contact with the drum (1) by a corona charging unit (5) which applies an electrostatic charge to the copy sheet (4) causing the toner image to be transferred thereto. The copy sheet (4) is separated from the drum (1) by a conductive belt (6). The belt (6) is initially grounded so that the leading edge of the copy sheet (4) is attracted thereto by induced electrostatic charge. A voltage of the same polarity as the transfer charge is then applied to the belt (6) to prevent transfer of the toner image back to the drum (1).

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Yokohama, Japan

Harumi Takahashi