Mita Industrial Co., Ltd.

Hiroshi Kageyama

Katsuhiro Yoshiuchi

Masahiko Fukano

Sueaki Okamoto

Seitaro Yoshida

Toshiyuki Nakade

Yoko Nishi

Shinji Ogaki

Koji Izumi

Hiroyuki Hamakawa

Akihiro Takada

Tetsuya Kagawa

Yoshiaki Tabata

Yoshihiko Tanaka

Kunio Nakai

Kenichi Ashida

Shunsuke Konashi

An image forming apparatus improved so that the leading end of a sheet can be exactly stopped in a nip position of registration rollers, and an image transferred to the sheet is not shifted. A locking device is provided in relation to the registration rollers provided in a conveying path. When the leading end of a cut sheet is inserted into the conveying path and is fed to the registration rollers, the registration rollers are brought into a state where it cannot be rotated by the locking device. Therefore, the leading end of the cut sheet fed is reliably stopped in the nip position of the registration rollers, and cannot enter the conveying path beyond this position. The conveyance of the cut sheet is thereafter resumed by the registration rollers and reaches a downstream pair of conveying rollers where the sheet is subjected to so-called secondary sheet feeding to an image forming section. At the same time, the locking device is turned off, whereby a load of the locking device is not applied to the registration rollers so that the registration rollers are freely rotated smoothly. When the trailing end of the cut sheet separates from the registration rollers, therefore, the cut sheet is not vibrated.

Image forming apparatus including registration roller locking device and

An image forming apparatus which is adapted to transfer an image on a roll sheet fed out of a roll body and transported through a transportation path to an image forming section. When a user opens a front door of the image forming apparatus and sets a new roll body around a feed reel thereof, the leading edge of a roll sheet fed out of the roll body is located at a predetermined position in the transportation path. When the user closes the front door upon completion of replacement of the roll body, the roll sheet is further fed out, and a leading edge portion of the roll sheet having a predetermined length from the leading edge thereof is cut off. The cut-off portion is discharged through the transportation path out of a main body of the image forming apparatus in the same manner as in an ordinary sheet transportation process.

Image forming apparatus capable of automatically discharging a cut-off

An image forming apparatus having a structure in which it is judged whether or not the trailing end of a continuous sheet is fixed to a feeding reel. The continuous sheet wound around the feeding reel is pulled out, and is conveyed through a conveying path passing through an image forming section. When the continuous sheet is conveyed, the rotation or the stop of the feeding reel is detected. When the stop of the rotation of the feeding reel is detected while the continuous sheet is being conveyed, it is judged that the continuous sheet has been used up. The continuous sheet is further conveyed for a predetermined time period after the judgment. It is judged whether or not the trailing end of the continuous sheet is fixed to the feeding reel depending on whether or not the continuous sheet exists in a predetermined position of the conveying path.

Image forming apparatus which detects rotation of a continuous sheet

An image forming apparatus capable of cutting a strip-shaped continuous sheet on which an image is formed to a desirable cutting length. A rolled-sheet is conveyed by registration rollers and the like. The rolled-sheet is further led to the vicinity of a photosensitive drum through pre-transfer rollers. The rolled-sheet to which a toner image has been transferred is subjected to toner fixing processing by a fixing device. When the leading end of the rolled-sheet reaches the pre-transfer rollers, the rotational speed of a sheet feeding motor is increased during a predetermined time. Consequently, the sheet conveying speed on the upstream side of the pre-transfer rollers in a direction of sheet conveyance is increased, thereby forming slack in a sheet portion between the registration rollers and the pre-transfer rollers. Consequently, tension exerted on a sheet portion between the fixing device and the pre-transfer rollers does not affect the conveyance of the sheet by the registration rollers. If operation timing of a cutting mechanism is determined on the basis of the number of output pulses of a pulse output unit for detecting rotation of the sheet feeding motor, therefore, the rolled-sheet can be reliably cut to a desirable length.

Image forming apparatus adapted to feed continuous rolled-sheet paper by

An image forming apparatus capable of simplifying work for removing a sheet by a user after a jam occurs. An image is formed on a sheet having a predetermined length cut from a rolled-sheet. A cutting mechanism is provided in a halfway portion of a conveying path through which the sheet passes. When a jam occurs in the conveying path, the cutting mechanism is operated, whereby the sheet is cut. The sheet in the apparatus can be immediately removed, therefore.

Image forming apparatus

A fixation control device is provided which controls the operation of a fixing unit having a heat roller and a press roller between which a sheet is passed. When copies are successively made on a plurality of narrow-size sheets, the temperature of the end portions of the press roller rises and, therefore, the difference between the temperatures of the end portions and the central portion of the press roller becomes greater. The greater temperature difference results in a diameter difference between the central portion and the end portions of the press roller due to thermal expansion, thereby reducing sheet transportation ability of the heat roller and press roller. However, the fixation control device of the present invention can compensate the reduction in the transportation ability by increasing the rotational speed of the heat roller and press roller when the temperature difference becomes greater.

Fixation control device

A fixation temperature control device is to be applied to a copying machine or the like. A control section determines a heat roller control temperature in consideration of a detected press roller temperature. When the heat roller temperature is lower than a reference temperature, a correction value is added to a heat roller reference temperature to set the heat roller control temperature higher than usual. When a fixing unit is in a stand-by status and the press roller temperature is in a temperature range between 80.degree. C. and 90.degree. C., a heat roller and a press roller are preferably rotated at a speed lower than a usual rotational speed.

Fixation temperature control device

An image forming apparatus includes a toner image forming device for forming a toner image corresponding to an image of an original document at a set operative copying magnification, a transfer device for transferring the toner image onto a copy item, a fixing device for fixing the toner image on the copy item under heat, a memory for storing correction values for a plurality of types of copy item usable in the image forming apparatus respectively, the correction value being adapted for correcting a change in length of a copy item due to the heat of the fixing device, a judge device for judging what type the present copy item is of, and a magnification setting device for setting an operative copying magnification to correct a shrink of the present copy item due to the fixing heat.

Image forming apparatus capable of copying images on various copy items

A developing apparatus includes a developing roller having a magnet roller for feeding a developer to a photoconductor, and a toner concentration sensor for detecting a toner concentration of the developer, a region of the magnet roller corresponding to a location of the toner concentration sensor, being substantially zero gauss as magnetic flux density distribution.

Developing apparatus and manufacturing method of developing roller

A toner hopper which is arranged upwards of the developing unit is elevatably supported in the image forming device in the vertical direction thereof and the connection between the toner hopper and the developing unit can be cancelled by lifting up the toner hopper when drawing out the developing unit so that the structure of the connection portion therebetween can be simplified and the sliding portion can be eliminated to thereby eliminate wearing at the connection therebetween. Furthermore, an apparatus for automatically raising and lowering the toner hopper and an apparatus for maintaining the horizontality of the toner hopper when being elevated and lowered is provided.

Developer unit and a toner hopper for an image forming device

A corona wire cleaning device for a corona unit for cleaning corona wires stretched in a shield case, comprising: a driving wire wound on a driving pulley and an idle pulley for reciprocating motion along the length of the corona wire; and a cleaning member slidably mounted in the shield case for traveling motion in association with the reciprocating motion of the driving wire and having a cleaning tool which rubs and cleans the corona wire by the traveling motion thereof in one direction and which comes away from the corona wire by the traveling motion thereof in the other direction, whereby a foreign matter such as dust can be surely removed from the corona wire, thereby accomplishing reliable cleaning of the corona wire.

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Osaka, Japan

Hiroshi Kageyama