Matsushita Electric Industrial Co., Ltd.

Tadafumi Shimizu

Masahiro Samei

Keiichi Matsuzaki

Hideki Tatematsu

Kazunori Matsuo

Kenji Asakura

Shoichi Kitagawa

Shouichi Kitagawa

Masaru Imai

Tadayuki Kajiwara

Kazuhiko Soeda

Yuichi Monda

Eiji Torikai

Tomoyuki Noguchi

Hidehiko Inokuchi

Hirofumi Ihara

Hiroyuki Noda

Junichi Terayama

Tetsuya Mitsuyasu

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

An image heating apparatus that enables a temperature of an image heating element to be stably maintained at a target temperature as a fixing speed varies. A Proportional-Integral-Derivative (PID) controller determines whether a temperature control computation results in a range that allows temperature control with one IGBT, and a linear control is performed if the result is at least equal to a minimum power obtained as IH output. PWM control is performed at minimum power if the power is less than a required minimum power. Thus, a computation method of a supply power computator need not be switched according to the fixing speed, and a calorific value of a fixing belt can be controlled using one computation method.

Image heating apparatus

A fixing apparatus is provided that enables a recording medium that has undergone heat-fixing to be separated smoothly from a heating medium without causing a sheet jam or image disturbance. In this apparatus, there are provided on the guide surface of a separator two step parts raised along the guide surface guide width direction. Recording paper is transported gripped by a fixing nip, is guided so as to come into contact with only the apex parts of step parts, and is separated from the surface of a fixing belt. Thus, a gap is formed between the guide surface and the heat-fixing surface of recording paper guided along the guide surface, the contact area between the heat-fixing surface of recording paper and the guide surface decreases, the heat-fixing surface of recording paper becomes less prone to adhere to the guide surface of the separator, and recording paper is smoothly separated from the fixing belt without causing a sheet jam or image disturbance.

Fixing apparatus

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

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.

In a fixing unit, a medium introducing portis provided near a gripping partof a housing, and a sheet materialto be subjected to a fixing process is guided to the medium introducing port. A shutteris provided slanted at a given angle with respect to a gripping surfaceof the gripping partof the fixing unitsuch that the shutter has a fulcrum at a part thereof, which is closer to the gripping partof the fixing unit, at the medium introducing port, and the shutteris turnable to a position to close the medium introducing portwhile resisting the urging forces of the twisted springs

Image forming apparatus having a removable fixing device

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.

A fixing device is formed by using a heat generating roller having magnetism and electric conductive characteristics and a magnetizing coil opposed to the outer peripheral of the heat generating roller and generating heat on the heat generating roller by an electromagnetic induction. The magnetizing coil is formed in such a manner that 60 copper wires whose surfaces are insulated and have the outside diameter of 0.2 mm are bundled to form a bundle of wires and the bundle of wires is drawn in the direction of rotation axis of the heat generating roller and wound in the direction of a circumference of the heat generating roller. Further, the magnetizing coil is disposed so that the bundles of wires mutually come into close contact along the circumference of the heat generating roller to cover the upper half of the heat generating roller.

Fixing device and image forming apparatus using the same

A heating device utilizing electromagnetic induction is provided with an induction heating unit that is opposed to a heating member and causes the heating member to heat through electromagnetic induction. The induction heating unit has an exciting coil for generating a magnetic field and a coil guide member on which the exciting coil is wound. The exciting coil is formed in at least two layers in such a manner that a first layer is formed on a circumferential surface of the coil guide member by winding a plurality of turns and a second layer is formed around and outside the first layer on the side opposite to the coil guide member, and winding of each of the second layer and following layers is started from a position close to a winding start position of the first layer.

Heating device and fuser utilizing electromagnetic induction

A short ring is provided outside a support frame. In the short ring, eddy current is generated in such a direction as to cancel apart of a magnetic flux developed from the exciting coil when it is fed with current, which the part of the magnetic flux leaks to outside. When the eddy current is generated, a magnetic field is developed in such a direction as to cancel the magnetic field by the leaking flux, as taught by Fleming's law. The result is that unnecessary radiation by the leaking flux is prevented, and hence noise generation in other members or devices is suppressed.

Heating device using electromagnetic induction and fuser

An image heating apparatus and heat generating rotary member for use in the image heating apparatus has a fixing roller including a magnetic metal layer and a non-magnetic metal layer, and the non-magnetic metal layer is provided on the outer side of the magnetic metal layer and is thinner than the magnetic metal layer.

Image heating apparatus and heat generating rotary member for use in the same

A fixing roller cooperates with a pressing roller to heat and press a toner image to a recording medium so as to fix the toner image to the recording medium. A sheet-like web is impregnated with a mold release for supplying the mold release to a surface of the fixing roller by being pressed by the pressing roller. A first shaft has an unused portion of the web wound therearound, and a second shaft takes up the web after supplying the mold release to the fixing roller. A coil spring applies a rotational force in a direction opposite to a direction of drawing out the web relative to the first shaft so as to apply a tension to the web, thereby automatically removing slackness of the web.

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Ogori, Japan

Tadafumi Shimizu