Mita Industrial Co., Ltd.

Kyocera Mita Corporation

Keiji Ban

Makoto Eki

Hiroaki Tsuchiya

Masami Fuchi

Hiroyuki Arima

Masayuki Mizuno

Susumu Taniguchi

Tetsuro Tomoe

Shinichi Tanaka

Katsuhide Yamaguchi

Osamu Yoshimura

Hideaki Kimata

Hiroshi Kobayashi

Masanori Yamaoka

Hiroki Morishita

Masaki Kadota

Yoshinori Makiura

Masao Otsuka

Hiroaki Nakamura

Kazushiro Taguchi

This invention relates to an image forming apparatus for recording an image on recording paper. The apparatus has a main base frame internally provided with an imaging unit for recording an image on recording paper, an upper frame disposed on-the main base frame and pivotally movable about an axis of a pivot provided on one end of the upper frame corresponding to a rear side of the apparatus to open a front side of the apparatus, a document feeder unit disposed on the upper frame for feeding an original document set thereon toward the front side, a document discharge tray attached to the main base frame for receiving the document fed by the document feeder unit, and a recording paper discharge tray attached to the main base frame beneath the document discharge tray for receiving the recording paper carrying the recorded image. The document discharge tray and the recording paper discharge tray are integrally attached to the main base frame via a tray frame to form a one piece unit.

Image forming apparatus

An image forming apparatus of this invention is constructed such that a main base frame constituting the apparatus is formed with a pair of first positioning pins. An attachment member is formed with a pair of second positioning pins and positioning holes for fittingly receiving the first positioning pins therein to position the attachment member relative to the main base frame. A brake force supplier formed with mounting holes is attached to the attachment member while positioned relative thereto by fitting insertion of the second positioning pins in the mounting holes. When the attachment member is not used, another brake force supplier can be directly mounted on the main base frame and positioned relative thereto by fitting insertion of the first positioning pins in mounting holes of the brake force supplier.

Positioning structure for brake force supplier for use in image forming

A helical gear connected to a lower discharge roller is made movable in its axial direction toward a bracket when a stepping motor is activated. A friction pad formed from felt or sponge rubber, for example, is attached to a side surface of the helical gear that is located face to face with the bracket. When the stepping motor is energized, the helical gear shifts toward the friction pad and the side surface of the helical gear comes in sliding contact with the friction pad. Resultant frictional resistance produces a braking force which acts on the rotating lower discharge roller. An overrun of the lower discharge roller due to a backlash between engaging gears is prevented even when an upper transfer roller exerts a forward-pushing force on a rear end of a sheet of an original document.

Document feeding devices for image reading apparatus

This invention relates to an image forming apparatus constructed such that an upper frame is openably mounted on a main base frame and a pivotal movement transmitter (gear) is rotatably mounted on the upper frame about an axis of a rotation of the upper frame, i.e., in association with the rotation of the upper frame. The gear has a cam portion. One end of a lever comes into contact with part of the cam portion of the gear, while the opposite end of the lever comes into contact with a coil spring. Further, a distance from the pivotal axis of the gear to the contact position of the lever with the cam portion decreases in accordance with a proceeding of the closing operation. Accordingly, as the lever (cam follower) follows the cam portion in accordance with the closing operation of the upper frame, a compression force to compress the coil spring increases. Thereby, a brake force applied to the upper frame on the way of closing also increases.

Open/close mechanism of upper frame for use in image forming apparatus

A sheet member conveying mechanism, including a conveying guide for guiding a sheet member from a paper feed port to a paper discharge tray, a forwarding roller disposed on the most upstream side of the conveying guide, and a paper feed roller disposed on the downstream side of the forwarding roller to convey sheet members, forwarded by the forwarding roller, downstream one by one. An upper part of the outer peripheral surfaces of each of the forwarding roller and the paper feed roller is exposed above the upper surface of the conveying guide. The uppermost site of the paper feed roller is located at a lower position than the uppermost site of the forwarding roller. In order to avoid contact with a curled front end portion of a sheet member positioned on the forwarding roller, the upper surface of the conveying guide is curved such that its height decreases, beginning at the downstream end of the exposed part of the outer peripheral surface of the forwarding roller toward the upstream end of the exposed part of the outer peripheral surface of the paper feed roller, as viewed in the axial direction.

Sheet member conveying mechanism

A conveying guide for conveying a sheet onto which an image has been transferred is made of a synthetic resin having a resistance higher than the resistance of the transfer sheet. The upstream side end of the upper surface of the conveying guide is located sufficiently lower than the position at which the sheet is separated from the surface of the photoreceptor drum. With these arrangements, the charging of the conveying guide due to the friction between the sheet and the guide is prevented, thereby restraining the image quality deterioration.

Image transferred sheet conveying guide for use in an image forming

A paper feeding device is capable of judging that a paper jam occurs on the basis of output from a first paper detecting switch and a second paper detecting switch. These paper detecting switches are respectively provided ahead of and behind a registration roller which feeds paper sheets to an image forming section. If the first paper detecting switch is turned on when a predetermined time has elapsed since the registration roller started to feed a paper sheet to the image forming section, it is judged that a duplicate paper feeding state has occurred where a plurality of paper sheets are simultaneously fed. If the second paper detecting switch is turned off in the case where it is judged that a duplicate paper feeding state has occurred, it is judged that a paper jam has not occurred. The registration roller is stopped so it will later be ready to feed the subsequent paper sheet. Even when the paper sheets are simultaneously fed in a duplicate paper feeding state, it is not judged that a paper jam occurs as long as the paper sheets are fed one at a time to the image forming section. However, if both the first and second paper detecting switches remain on after the predetermined time, then it is judged that a paper jam has occurred.

Image forming apparatus including a paper feeding device having improved

An apparatus for conveying sheet members, equipped with a conveyer guide member that extends from the downstream side of a toner image-transfer position of a photosensitive drum toward a fixing unit and a grounding plate member that is disposed on the lower surface side of the conveyer guide member. The conveyer guide member is made of a material having an electric resistance not smaller than the electric resistance of the sheet member, and the grounding plate member is made of a material having an electric resistance smaller than the electric resistance of the conveyer guide member.

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Osaka, Japan

Keiji Ban