Sharp Kabushiki Kaisha Corporation

Shogo Yokota

Toshiaki Kagawa

Toshihiro Tamura

Katsumi Adachi

Masashi Hirai

Tomohiro Maeda

Yoshiya Kinoshita

Hiroyuki Sawai

Tatuya Shinkawa

In an external heating type induction heating device in which a magnetic field producing means is arranged in the outer circumferential portion of a heating roller, two heat generating layers, namely a conductive shaftand a surface heat generating layer, are provided in the heating roller, and the surface heat generating layeris formed having a thickness through which passes a portion of an alternating magnetic field, and the conductive shaftat a center of the heating rolleris heated by a portion of the alternating magnetic field produced by the magnetic field producing means passing through the surface heat generating layerto link to the conductive shaftpresent at the center of the roller, thereby preventing a drop in a surface temperature of the heating roller

Induction heating device and image forming apparatus equipped with such induction heating device

A surface of a discharge electrode of an ion generating device of the present invention, other than a surface in contact with a dielectric body, is coated with a protective layer made of a metal that is gold or a combination of gold and nickel. This allows the ion generating device to generate ions evenly and stably, and to have a longer life.

Ion generating device with a discharge electrode on a dielectric body coated by a protective layer made of metal

A heating device of the present invention includes a fixing roller and a pressure roller placed in press contact with each other in a press contact region, wherein a recording material having formed thereon an unfixed toner image is heated (fixed) by passing through the press contact region, and is arranged so as to include a heat generating layer formed on the pressure roller, which generates heat by the induction heating, and an induction heating coil unit for heating the heat generating layer by the induction heating, which is formed so as to cover a part of an outer surface of the pressure roller. The heating device of the present invention having the foregoing structure permits the object to be heated in a short period time and shows excellent properties in terms of the saving of energy and the suppression of noise sound.

Heating device, fixing device, image forming apparatus and heating method

An upper heat roller with an external heat source and a lower heat roller with an internal heat source are arranged with a paper transport path therebetween, in such a manner as to be pressed against each other. The lower heat roller is heated sufficiently, thereby supplying a paper sheet with sufficient heat when the paper sheet is transported through a contact region between the upper and lower heat rollers to be heated.

Heating device and heating method

Curling of edges of recording paper in a toner-image fixing device is prevented. A temperature control unit controls the operation of a heater-lamp for heating a fixing roller in such a way that the fixing roller temperature when the front edge of recording paper enters into the fixing device is lower than the fixing roller temperature when a tail end of the recording paper enters.

Toner image fixing device for preventing curling of recording medium

A heat-resistant sheet is provided between a fusing roller and a pressing member made of a resilient material. The heat-resistant sheet is composed of a glass fiber substrate coated with or impregnating a fluororesin having good mold lubrication and heat-resistance, such as PFA and PTFE. A paper having a pre-fused toner image is carried through a section between the fusing roller and heat-resistant sheet. Accordingly, wear or separation of the heat-resistant sheet caused by friction with the fusing roller can be prevented, thereby improving durability of the heat-resistant sheet.

Fusing device

A toner image fixing device possesses excellent toner-releasing property and paper-carrying ability. A fixing roller is covered with a layer of compound of PTFE and fluoroelastomer.

Toner image fixing device

Energy saving in a fixing unit having a low heat capacity is achieved by reducing a loss of heat transferring from a temperature sensing element to temperature sensing unit and by improving response of the safety device. A heat-insulating member is formed to cover a temperature fuse being a temperature sensing element and a heat-conductive filler or heat-conductive elastic member is formed between the temperature fuse and a sliding sheet. A temperature sensing means having the temperature sensing element abuts on a fixing roller through a sliding sheet interposed therebetween. A contacting portion of the temperature sensing means with the heat-insulating member and the filler or elastic member has a curved contacting surface fitting a cylindrical surface of the fixing roller. The heat-insulating member has a groove or a slit for engaging with a protrusion of the temperature sensing element to be secured to the heat-insulating member.

Safety device for a toner image fixing device

A fixing device has a fixing roller, a press member disposed in a press state in an axial direction of the fixing roller on the periphery surface thereof, and a transport guide for guiding transport of paper. The press member is formed so that the free height of a guide part on an upstream side with respect to the transport direction of the paper is lower than that of the pressure portion pressed to the fixing roller via a heat resistant sheet. Therefore, since the apparent elasticity hardness of the pressure portion can be made relatively small, the nip width formed by the fixing roller and the press member can be made large. Consequently, the fixing of toner to the paper is improved. Even when, for example, a thin sheet of paper or an envelope is used as the paper, the fixing device can suppress the occurrence of paper jam, such as paper lodging, and improper paper insertion.

Fixing device for electrophotographic device

The inner surface of a fixing roller is divided into two areas in the lengthwise direction thereof. In one of the areas where the increase rate of the surface temperature of the fixing roller is small, and improper fixing to recording paper is likely to occur, black heat resistant coating is applied to the inner surface of the fixing roller to improve heat absorption. In addition, in the other area where the surface state of the inner surface of the fixing roller is non-uniform, and heat absorption is not stable, transparent heat resistant coating is applied to the inner surface of the fixing roller to stabilize the heat absorption. It is attempted in this manner to make uniform the temperature of the fixing roller in the lengthwise direction thereof and thus to make uniform the fixing in the whole paper-passing area.

Fixing device having surfaces with different thermal characteristics

A toner image fixing device has a heat-resistant sheet that possesses excellent durability, fixing ability, transporting ability and working reliability. In a toner image fixing device that has a fixing roller, a pressure member disposed as pressed against the fixing roller, and a heat-resistant sheet secured between the fixing roller and the pressure member and fixes a toner image on a recording medium by heat while the latter passing through nip portion formed between the fixing roller and the heat-resistant sheet. The heat-resistant sheet is a sheet made of synthetic resin PTFE containing polyimide.

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Fujiidera, Japan

Shogo Yokota