Fujitsu Corporation

Fuji Xerox Co., Ltd.

Tsuneo Mizuno

Atsushi Tano

Tadashi Matsuda

Noboru Takada

Hiroki Ohta

Tomoaki Tanaka

Hiroki Ushiroda

Akira Nakazawa

Eiji Suzuki

Katsumi Sugimoto

Tetsu Takahashi

Kenji Fuke

Mitsuo Ozaki

Katsuya Shimatsu

Hideki Kamaji

Sadaaki Yoshida

Shigeo Nonoyama

Yasuhiro Wakabayashi

Hiroshi Kera

Tohru Satoh

Michio Shimura

Teturou Nakashima

Hitoshi Yoshii

Shigeru Yoshikawa

Kazumi Kawabata

Toshihiro Yukawa

Yoshimi Takizawa

An image forming apparatus in which respective color visible images on tandem-arrayed plural photoconductor drums are sequentially overlay-transferred onto an intermediate transfer belt by application of a primary transfer voltage by intermediate transfer rollers, then the images are transferred at a time from the belt onto a print sheet by application of a secondary transfer voltage by a paper transfer roller. The same primary transfer voltage is applied to the respective color intermediate transfer rollers from one power source. In the intermediate transfer belt, a relative dielectric constant, a surface resistance and a volume resistance are controlled such that potential charged by initial transfer is attenuated to &#x2153; or lower than the transfer voltage before a belt position of the initial transfer arrives at a next transfer position.

Image forming apparatus

The present invention relates to a color image forming device for forming toner images of a plurality of colors on a medium, and is for improving second transfer efficiency from an intermediate transfer body to the medium. The device has image forming units (-to-) for forming the toner images of the plurality of colors on at least one image bearing body (-to-) by a plurality of developing units (-to-) respectively accommodating toner of different colors; an intermediate transfer body (); primary transfer means (-to-) for primary transferring the toner images of the plurality of colors onto the intermediate transfer body sequentially for the respective colors; and secondary transfer means () for secondary transferring the toner images of the plurality of colors on the intermediate transfer body onto the medium. The image forming units form the toner images of the plurality of colors so that the potentials of toner layers transferred onto the intermediate transfer body () are progressively lower in the order in which the plurality of colors are transferred. Since the potential of the toner layer directly adhered to the intermediate transfer body is higher, the directly adhered toner layer becomes easier to be secondary-transferred, and thereby, the secondary transfer efficiency is improved and the reproducibility of the secondary color is improved.

Color image forming method and color image forming device

An image forming apparatus or method which uses plural image forming units to form visible images of different colors by making developers of different colors adhere to image holders such as photosensitive drums electrostatically. In this apparatus or method, intermediate transfer electrode members such as intermediate transfer rollers are opposite to the image holders of the image forming units with a belt transfer member between them and voltage is applied to transfer images electrostatically from the image forming units to the belt transfer member in sequence in a way that the transferred images on the belt overlap each other. Each of the intermediate transfer electrode members is located on the belt surface away from a point (transfer nip) at which a corresponding image holder contacts the belt.

Image forming apparatus and imaging method

A development device includes: a development roller a surface of which is made of electrically resistant material; a blade that comes in contact with the development roller so as to form a layer of developing agents, and has a predetermined thickness on the development roller, and possesses electrical conductivity; a bias power supply that applies a bias to the development roller and the blade; and a resistance provided between the blade and the development bias supply to establish electric connection therebetween. The resistance may be incorporated in the blade itself.

Development device and development method, and image-forming device

It is an exemplified object of the present invention to provide a developer, a development device and its elements, and an image-forming device that can more stably form a high-quality image by a relatively inexpensive and easy means. A noncontact-type development method according to the present invention utilizes a nonmagnetic and single component toner having a volume average particle diameter D (&mgr;m) and an average specific charge q/m (&mgr;C/g), a development roller having a ten-point average surface roughness Rz (&mgr;m), and a blade keeping in contact with the development roller at a blade line pressure Pb (gf/cm). In order to stably form a uniform toner layer dt (&mgr;m) on the development roller, the following relationship is to be met: dt&equals;1.8&times;&lcub;q/m&times;Rz/(Pb&minus;1)&rcub; &times;D&plusmn;0.25 D, and 1.5 D&lE;dt&lE;3.5 D.

Developer, development method, development device and its elements, and image-forming device

This invention relates to a non-contact developing method for applying a driving voltage, which is an AC voltage superimposed on a DC offset voltage, to a non-contact developing roller to develop toner, and which prevents the selective developing phenomenon from occurring. The velocity ratio between the flying velocity of toner with a large particle size and the flying velocity of toner with a small particle size changes according to the driving frequency f of the AC voltage ( ) applied to the developing roller, so by setting the driving frequency f of the AC component within a range where selective developing of the toner does not occur, it is possible to effectively prevent the selective developing phenomenon from occurring.

Non-contact developing method, non-contact developing device and image formation device

It is an exemplified object of the present invention to provide a development device and process, and an electrophotographic image-forming device that can more stably supply toner to and collect the toner from a development roller, and charge the toner, and thus can obtain a higher-printing-quality image than was previously possible. To achieve this object, the toner supply and collection are carried out by electric force (potential difference) while preventing the toner from deteriorating by providing a gap between a reset roller and the development roller, whereby a high-quality image-forming is possible even when printing is performed for a long time. Excellency in uniformity of charge in the toner makes it possible to stabilize capability of supplying the toner and to improve image quality.

Development device for use with an electrophotographic image-forming device

The electrophotographic recording device and method of transferring the recorded medium provide excellent separating capabilities. The electrophotographic recording device has a separator section located along a feed path of printing paper at a front stage of the transfer roller. At the separator section, the printing paper is dielectrically polarized to make its surface facing a photosensitive drum charged in the same polarity as that of the photosensitive drum before the printing paper is brought into contact with the photosensitive drum. The paper is separated from the photosensitive drum after the transfer process due to the electrostatic repulsion on a contact surface between the photosensitive drum and the paper.

Electrophotographic recorded device having excellent separating capabilities and method of transferring the recorded medium

An electrostatic recording system using a dielectric belt for conducting electrification of a sheet of paper and a transfer belt so that the sheet of paper is not wound and caught by a photoconductor drum, and a transfer voltage can be lowered so as to smoothly separate the sheet of paper from a transfer belt. The electrostatic recording system applies a voltage to only the dielectric belt at a stage before the sheet of paper 3 is attracted to the dielectric belt 10 and applies voltage to the sheet of paper 3 conveyed to the dielectric belt, and to the dielectric belt 10 while the sheet of paper and the belt are mutually superposed.

Electrostatic recording system using dielectric belt in which

A blade controls a layer thickness of the developer and/or triboelectrically charges the developer on a surface of the developing roller in an electrographic imaging device. The blade is a longitudinally extended member made by punching a thin resilient plate of metal in a press mold, and a tip portion thereof has a curved tail part having a smooth surface and a gradually reduced thickness formed as a shear drop upon punching.

Developer thickness-controlling blade and production process thereof as

A pressure damper of an ink jet printer provided in an ink feed line between an ink jet head and an ink tank to absorb a pressure fluctuation in the ink feed line, wherein the pressure damper has a damper body provided with a pressure absorbing chamber and a filter incorporated therein to filter the ink.

Pressure damper of an ink jet printer

An apparatus for ejecting droplets of ink including: a passage for ink; an orifice disposed at one end of the passage; a pressure-applying device for applying a pressure wave to the ink within the passage; and a signal-supplying device for supplying an actuating signal to the pressure-applying device. The frequency of the signal is such that the displacement of the ink surface at the orifice due to the pressure wave is maximized.

Apparatus for ejecting droplets of ink

Ink jet printing head

A method for driving an ink jet printer which includes an electro-mechanical transducer which is operated by electrical pulses to eject ink from an ink nozzle connected to pressure chamber wherein two successive electrical pulses are supplied to the transducer before the ejected ink is separated from the remaining ink in the pressure chamber.

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Kawasaki, Japan

Tsuneo Mizuno