Minolta Company, Ltd.

Konica Minolta Business Technologies, Inc.

Minolta Camera Kabushiki Kaisha

Yasuhiro Ohno

Ken Tanino

Toshiya Natsuhara

Masami Miyazaki

Masahiro Anno

Makoto Fujii

Eiichi Sano

Yuji Kamoda

Haruo Iwahashi

Hideo Hotomi

Kazuomi Sakatani

Kazuyuki Fukui

Takanobu Yamada

Tomohiko Masuda

Hiroyuki Ideyama

Yoshihiro Fukuhata

Yoshinobu Hada

Hideaki Kodama

Kazuo Mohri

Makoto Takase

Shoukou Gon

Masakazu Takahashi

Tomihiko Masuda

In a fixing device, a magnetic flux generated by a coil passes through a magnetic circuit made of a heat generating layer of a fixing member and a magnetic substance core. The magnetic substance core includes a plurality of main cores each having an elongated form along a circumferential direction of the fixing member and arrayed at intervals along a width direction of a sheet. The end row main cores have a second shape effectively closer to an outer peripheral face of the fixing member compared to a first shape possessed by the central row main cores so as to enhance density of the magnetic flux, which passes the magnetic circuit, more in end sections than in a central section with respect to width direction of the sheet.

Fixing device

A fixing device includes a magnetic flux generating section having a coil which generates a magnetic flux when applying current, a fixing roller having a heat generating layer having a thickness of 100 &#x3bc;m or less formed along an outer peripheral surface of the fixing roller for generating heat through electromagnetic induction by the magnetic flux, a capacitor connected in series to the coil to constitute a series resonant circuit, and high frequency power supply circuits for applying voltage having a certain drive frequency to the series resonant circuit so as to make the fixing roller generate heat through the magnetic flux generating section. An image is fixed onto a sheet, which is transported in a state of being in pressure-contact with the outer peripheral surface of the fixing roller, by heat from the heat generating layer of the fixing roller.

When a fixing rollergenerates heat by a magnetic flux generating sectionduring a standby time, a control sectionrotates the fixing roller. This prevents the fixing rollerfrom locally generating heat and being damaged. Moreover, the control sectionrotates and heats a pressure rollerduring the standby time, which makes it possible to keep the pressure rollerat a specified temperature and to reduce a time taken for a fixing device to recover from the standby state.

Fixing device with a magnetic flux generating section and a control section

An induction heating device for inductively heating an object to be heated which is formed of conductive material has a holder. The device also has a coil for inductively heating the object. The coil is supported by the holder. The coil is composed of a plurality of turns of conductor forming a layer, which is positioned along the object. Between conductor sections of the coil through which electric currents respectively flow in the same direction is formed a gap through which temperature of the object is detected. The device is capable of accurately detecting the temperature of heating region of the object, at low cost, and capable of increasing stability and safety in control of the temperature.

Induction heating device, induction heating fixing device and image forming apparatus

An induction heating device for inductively heating an object to be heated which is formed of conductive material has a holder. The holder is positioned outside the object. The device has an exciting coil for inductively heating the object. The exciting coil is supported by the holder. The exciting coil is composed of a plurality of turns of conductor forming a layer, which is positioned along the object. The device also has a demagnetizing coil which is positioned along the layer of the exciting coil. In the demagnetizing coil, a back electromotive force is induced in accordance with a magnetic field produced by the exciting coil, so as to cancel the magnetic field. Stability in the temperature control for the object such as a heating roller can be improved by effective function of the demagnetizing coil. The device can be miniaturized and configured at low cost.

A heat fixing device for heat fixing a toner image to a receiving medium having a pair of fixing belts in an endless form; a pair of rotary members individually disposed on a respective inside circumference of the fixing belts and pressed against each other via the fixing belts; a pair of fixing members individually disposed on the respective inside circumference of the fixing belts and pressed against each other via the fixing belts; and a heating element for heating at least one of the fixing belts, wherein the fixing belts contact the rotary members and the fixing members only at a respective portion thereof via which the respective pair of rotary members and fixing members are pressed against each other.

Heat fixing device and image forming apparatus

The fixing device of the present invention comprises a heating roller having an internal heating device; a flexible fixing belt wrapped around the exterior side of the heating roller and having a circumferential length longer than the circumferential length of the heating roller; and a pressure roller for pressing against the heating roller through the fixing belt, wherein a slack part of the fixing belt is formed on the downstream side from the pressure contact part between the heating roller and the pressure roller in the direction of transport of the recording medium, such that this slack part touches the exterior surface of the pressure roller.

Fixing device provided with a fixing belt

The present invention related to a toner used in a toner-jetting system wherein the toner is jettingly adhered to a recording medium in a direct manner, the toner having a specific cohesion degree, a specific distribution of a particle size and/or a specific mean roundness.

Toner for toner-jetting

The present invention related to a toner used in a toner-jetting system wherein the toner is jettingly adhered to a recording medium in a direct manner, the toner having a specific aerated bulk density, a specific distribution of a particle size and/or a specific mean roundness.

The present invention related to a toner used in a toner-jetting system wherein the toner is jettingly adhered to a recording medium in a direct manner, the toner having a specific angle of repose, a specific mean roundness and/or a specific distribution of a particle size.

The present invention relates to a toner used in a toner-jetting system wherein the toner is jettingly adhered to a recording medium in a direct manner, said toner satisfying a specific relationship between an average quantity of charge (x)(&mgr;C/g) and a distribution deviation of quantity of charge (y).

The present invention provides an ink jet printer which performs recording by causing a nozzle to discharge an ink drop onto a recording medium. The nozzle is connected to an ink channel in which aqueous ink is housed. The printer head can vary the dot size on the recording medium by changing the size of the drop that is discharged from the nozzle. The aqueous ink has a degree of surface tension change .DELTA.S that is expressed by the relation .DELTA.S=(S.sub.1 -S.sub.3)/ S.sub.2 of 0.3 or less, wherein S.sub.2 is the surface tension at 25.degree. C., and has a value of 20 to 50 dynes/cm, S.sub.1 is the surface tension at 5.degree. C., and S.sub.3 is the surface tension at 40.degree. C.

Apparatus and method for ink jet recording

In an electrophotographic copying machine, image quality is improved by suppressing phenomena such as narrowing and thickening of a linear image or discharge noises in a photograph image due to anomalies on transfer of a toner image. For example, a document type is discriminated and when a transfer brush is used for transfer, transfer current and pretransfer erasing are controlled according to the type of document image. The pretransfer erasing is controlled in various following situations: Bi-level exposure method or multi-level exposure method, edge emphasis, photoelectric efficiency, the surface potential of the photoconductor, and position of a developing device.

Image forming apparatus with enhanced pretransfer erasing

In a digital image forming apparatus, a user can select a desired gradation curve representing the relation of the density of reproduced image to the input image signal obtained by reading a document among a plurality of gradation data stored in a memory in correspondence to image forming conditions of an electrophotographic process of forming an image. The image forming condition is determined separately. A gradation correction data is calculated from the gradation data to realize the object gradation curve. Then, an input image signal is converted to light quantity data for a beam for exposing a photoconductor by using the calculated gradation correction data to form a latent image on a photoconductor in the image forming conditions.

Digital image forming apparatus having gradation characteristic setting

An image forming apparatus having an image editing function and a plurality of developing devices capable of developing different colors respectively, wherein, for example, where images are copied from two sheets of document or a double-side document on the both sides of a copying paper, or where the both pages of an opened book are copied in a split manner, the position on a copying paper of change-over of the developing device is set only for one sheet of document in double-size copy from the respective two sheets of document, only for one page of the opened book, and only for one side of the double-side document, and thereby the position of change-over is determined automatically for the other sheet of document, the other page or the rear side, and therefore the devices for setting the position of change-over of the developing device are reduced in number, and the operation is simplified.

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Toyokawa, Japan

Yasuhiro Ohno