Matsushita Electric Industrial Co., Ltd.

Panasonic Corporation

Masaru Imai

Kenji Asakura

Hideki Tatematsu

Noboru Katakabe

Keisuke Fujimoto

Masahiro Samei

Keiichi Matsuzaki

Hiroshi Terada

Kazunori Matsuo

Akinori Toyoda

Tadafumi Shimizu

Shoichi Kitagawa

Syuichi Watanabe

Akihiro Yasuda

Noriyuki Tajima

Hideaki Yamada

Masaaki Nakano

Masaomi Inoue

Syuuiti Watanabe

Tomoyuki Noguchi

Youichi Nakamura

Masakazu Mizusaki

Shuichi Watanabe

Naoto Matsuo

Kenji Matsushita Electric Ind Co Ltd Asakura

A fixing unit is provided with a fixing belt that heats recording paper that bears and moves a toner image, an exciting coil that generates magnetic flux in the fixing belt and causes the fixing belt to produce heat by electromagnetic induction, and a heat production adjustment section that adjusts the calorific value distribution of the fixing belt by adjusting the magnetic flux acting upon the fixing belt.

Image heating apparatus and image forming apparatus including synchronization of magnetic flux generation

A heat generating roller, fixing equipment and an image forming apparatus in which warm-up time is shortened while preventing excessive temperature rise and good fixing performance is realized by preventing offset. The heat generating roller is formed principally by laying a high permeability conductive layer and a nonmagnetic conductive layer in layer. When a voltage is applied from a power supply to an exciting coil and an alternating current flow, magnetic flux is generated around the exciting coil and a magnetic field is formed. Magnetic coupling of a system including the heat generating roller and the exciting coil is advantageous at a low temperature and heat generation of the heat generating roller is accelerated. When the Curie point is exceeded, skin depth increases and skin resistance decreases, which suppresses generation of Joules heat and reduces heat generation of the heat generating roller.

Heat generating roller, fixing equipment, and image forming apparatus

In a fixing apparatus using an induction heating type of heating apparatus, there are provided an excitation apparatus that generates magnetic flux, an opposed core located opposite the excitation apparatus, a fixing belt that is induction-heated by the aforementioned magnetic flux, and magnetism masking elements that block magnetic paths corresponding to paper non-passage areas of fixing belt between the excitation apparatus and the opposed core. By blocking magnetic paths between the excitation apparatus and the opposed core by the magnetism masking elements, magnetic flux that induction-heats the fixing belt is effectively masked, and an excessive rise in temperature of paper non-passage areas of fixing belt is prevented.

Fixing device

An image heating apparatus is provided that enables the entire width of a heat-producing medium to be heated uniformly and an excessive rise in temperature to be prevented, without making the configuration complex. In a fixing unitin which this apparatus is applied, a fixing beltis an annular member that has an inner peripheral surface and an outer peripheral surface, and produces heat through the action of magnetic flux. An exciting coilis located in proximity to the outer peripheral surface of fixing beltand generates magnetic flux that acts upon fixing beltA suppression memberis located in proximity to inner peripheral surface of fixing beltand reduces, of the magnetic flux generated by exciting coilmagnetic flux that acts upon a paper non-passage area of fixing belt

Image heating device and image forming device

A fixing apparatus that enables the calorific value of a heat-producing rotating element to be stabilized and the heat production efficiency of that heat-producing rotating element to be improved. A fixing apparatus () is equipped with a heat-producing sleeve (), an induction heating apparatus (), a magnetic field absorption member () that absorbs a magnetic field generated by the induction heating apparatus (), and a fixing roller () and pressure roller () that grip and rotate the heat-producing sleeve (). The magnetic field absorption member () is located in an area opposite an exciting coil () with the heat-producing sleeve () between, and absorbs a magnetic field generated by the induction heating apparatus (). The heat-producing sleeve () is composed of a nonmagnetic metallic material of thickness in the range from 10 &#x3bc;m to 500 &#x3bc;m and specific resistance of 80&#xd7;10&#x3a9;cm or less.

Fixing apparatus

The present invention relates to an image forming apparatus that enables the occurrence of print defects due to a first print start time delay to be eliminated without using a temperature sensor that has a small thermal time constant. When the temperature of a fixing belt serving as an image heating body is greater than or equal to a predetermined temperature following the elapse of a fixed time after an image forming operation is started, recording paper is transported to a nip area (fixing area) of a fixing apparatus before the temperature detected by a temperature sensor reaches a predetermined image fixing temperature, and an image forming operation is started immediately.

Method and apparatus for controlling image forming operation of an image forming apparatus

A fixing apparatus can prevent an excessive rise in temperature of a paper non-passage area due to diverted flow of magnetic flux from a paper passage area of a heat-producing element to a paper non-passage area thereof has a small configuration. A center core is rotated by a rotation section, bringing cutaway parts to a magnetic path masking position, and the degree of magnetic coupling between the center core and a heat-producing roller is weakened, suppressing an excessive rise in temperature of paper non-passage areas of the heat-producing roller. With this fixing apparatus, switching of the intensity of magnetic coupling between the center core and heat-producing roller can be performed simply by rotating the center core. Also, with this fixing apparatus, it is not necessary for magnetism suppressing elements to be provided as separate members, enabling the configuration to be made simpler and less expensive.

An electromagnetic induced heating roller comprises a core member, an elastic layer, induction heating layer, and a mold release layer in this order from inside to outside. Further, a magnetic shield layer for preventing a magnetic flux from penetrating into the core member is interposed between the induction heating layer and the core member. The production of an alternating magnetic field from a magnetic field generating device, a leakage flux having penetrated through the induction heating layer is trapped by the magnetic shield layer. As a result, most of the impressed alternating magnetic flux is consumed for heating the heating layer, resulting in an improvement in the heating efficiency. A trouble is prevented which is generated by heating the bearing of the core member.

Electromagnetic induction heat generating roller, heating device, and image forming apparatus

A heating roller () includes a heat generating layer () that generates heat by electromagnetic induction, a heat insulating layer (), and a supporting layer (), which are provided inwardly in this order. The supporting layer () is formed of a material having a specific resistance of 1&#xd7;10&#x3a9;m or higher. Therefore, even when the heat generating layer () has a thickness smaller than a skin depth, i.e. a thickness defined by a flow of an induction current, so that magnetic flux penetrates the heat generating layer () and even reaches the supporting layer (), heat generation of the supporting layer () under an eddy current can be suppressed. Thus, the heat generating layer () can be decreased in thermal capacity, and heat generation of the supporting layer () is suppressed, so that only the heat generating layer () can be heated efficiently. As a result, a warm-up time can be reduced. Further, breakage by heat of, for example, bearings supporting the heating roller () can be prevented.

Heating roller, image heating apparatus, and image forming apparatus

An image heating device according to an embodiment of the present invention includes a heat generator that has an outer surface and that generates heat by induction heating and a heater positioned close to the outer surface of the heat generator, the heater being configured to heat the heat generator by induction heating. A positioner is located close to an end of the heater, the positioner being configured to position the heater with respect to the heat generator. A vibration absorber is attached to the positioner and is configured, in one embodiment, to viscoelasticly absorb vibration of the heater produced by a vibration caused by an electromagnetic repulsive force acting between the heat generator and the heater when the heater heats the heat generator by induction heating.

Image heating device

An image heating device is operational to estimate a temperature of a pressure roller so as to determine a set temperature for a roller belt in a subsequent image heating period.

Image heating device, image forming apparatus, image copying machine, and method for controlling temperature

A heating roller () includes a heat generating layer () that generates heat by electromagnetic induction, a heat insulating layer (), and a supporting layer (), which are provided inwardly in this order. The heat generating layer () is composed of at least two layers that are a first heat generating layer of a magnetic material and a second heat generating layer of a non-magnetic material. The first heat generating layer has a specific resistance higher than a specific resistance of the second heat generating layer and a thickness larger than a thickness of the second heat generating layer. This allows the second heat generating layer to function effectively as a heat generating part that generates heat by electromagnetic induction. Thus, compared with the case where the heat generating layer () is formed only of a single layer of a magnetic material, heat generation efficiency is increased, thereby allowing warm-up time to be reduced. Further, the heat generating layer () is heated intensively, so that heat generation of the supporting layer () is reduced, thereby allowing the prevention of breakage of, for example, bearings supporting the heating roller ().

Heating roller, heating belt, image heating device, and image forming device

An image heating device is provided with reduced cost, by which a difference in glossiness among printed images on recording media is eliminated, and the wrapping of a belt and the like at a high temperature is prevented. In the image heating device, a controller estimates a temperature of a pressure roller according to at least one of a temperature of a belt detected by a temperature sensor and a variation with time in the detected temperature from completion of the heating after application of an electric power to the magnetization coil by an exciting circuit is stopped and the heating of the belt by the heating roller is stopped, so as to determine a set temperature for the belt in a subsequent image heating period.

A fixing device as an image heating device is provided, by which a difference in glossiness is not caused in a recording medium in the axial direction of a pressure roller. When a print request is issued during the end-processing sequence, an electric power applied to a magnetization coil via an exciting circuit is dropped to 0 by controlling means during the start-processing sequence, and after an appropriate interval, the heating with full power is restarted by the controlling means. By so doing, the decrease in temperature at both ends of a fixing belt and a heat-generating roller in the axial direction can be compensated.

An image heating device includes a heat generating member that heats a body to be heated that is allowed to travel while carrying an image, an excitation unit that is provided close to the heat generating member and generates magnetic flux so as to cause the heat generating member to generate heat by electromagnetic induction, and a heat generation suppressing unit that suppresses an amount of heat generated in the heat generating member by regulating magnetic flux generated by the excitation unit. The heat generation suppressing unit suppresses heat generation of the heat generating member in a region corresponding to a region including at least a center portion of the body to be heated in a width direction. Thus, an amount of heat generated in the width direction can be regulated using a simple configuration at a reduced cost. Further, when the heat generation suppressing unit is operated, diffusion of magnetic flux into a wide area can be prevented.

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Hirakata, Japan

Masaru Imai