Canon Kabushiki Kaisha

Hiroaki Sakai

Atsushi Iwasaki

Hiroyuki Sakakibara

Norio Hashimoto

Yuko Sekihara

Masaaki Takahashi

Seiji Saito

Kazuo Kishino

Katsuhisa Matsunaka

Hiroshi Takami

Masaru Shimura

Mitsuhiro Ito

Tomoyuki Makihira

Takeshi Kawamura

Akira Kato

Yasunari Kobaru

Tomohiro Nakamori

Masafumi Maeda

Shigeo Miyabe

Kazushi Watanabe

Tadayuki Tsuda

Toshiyuki Karakama

Kaoru Sato

Shinjiro Toba

Kazuhiro Funatani

Junichi Kimizuka

Hiroshi Kataoka

Hideki Matsumoto

Masaharu Ohkubo

Akimichi Suzuki

Hiroto Hasegawa

Kazuaki Ono

Takayasu Yuminamochi

Shuji Saito

Tatsuto Tachibana

Masaru Tsukada

Minoru Matsuguma

Seietsu Miura

An image forming apparatus includes an exposure device having an adjustment period for adjusting an output while exposing a photosensitive drum to light prior to image formation and a developing device. The developing device is configured to change between a contact state where the photosensitive drum and a developing roller are in contact with each other and a separation state where they are separated from each other. The developing device changes from the separation state to the contact state when a portion on the photosensitive drum exposed to light in the adjustment period of the exposure device is at a developing position.

Image forming apparatus

An image forming apparatus includes an image forming unit, a fixing unit, and a power control unit. The image forming unit forms an unfixed image on a recording material. The fixing unit includes an endless belt, a heater held in contact with the endless belt, a pressurization roller to form a fixing nip portion for pinching and conveying the recording material together with the heater via the endless belt, and a pressure changing mechanism to effect switching between a pressurization state and a pressure release state. The power control unit controls power to the heater. In response to transitioning from the pressure release state to the pressurization state, the power control unit starts power to the heater during a transition period before the pressurization state is attained and controls power to the heater such that a heater temperature does not exceed a predetermined upper limit temperature during the transition period.

Image forming apparatus with heater

The image heating apparatus includes a rubber layer and a resin tube layer on a metal core. The rubber layer includes a solid rubber layer having a thermal conductivity in a thickness direction of 0.16 W/(m&#xb7;K) or more and 0.40 W/(m&#xb7;K) or less, and a self-bonded silicone rubber layer that contains a filler of 5 vol % or more and 40 vol % or less, and has a thermal conductivity in an axial direction of 2.5 W/(m&#xb7;K) or more and a thickness of 0.5 mm or more and 5.0 mm or less, the filler having a length of 0.05 mm or more and 1 mm or less and a thermal conductivity in a length direction of 500 W/(m&#xb7;K) or more, so that a pressure roller to moderate temperature rise in a non-sheet feeding area when a small sized recording material has undergone sheet feeding can be easily manufactured.

Image heating apparatus, pressure roller to be used in the image heating apparatus, and manufacturing method for the pressure roller

A pressing member for creating a nip in which the pressing member contacts a heating member and a recording material is heated while being nip-conveyed, includes an elastic layer and a high thermal conductive elastic layer, which is provided on the elastic layer and has a thermal conductivity which is higher than that of the elastic layer. In the high thermal conductive elastic layer, carbon fibers and carbon nanofibers are dispersed in a heat-resistant elastic material.

Pressing member and image heating member using the pressing member

A pressure roller forms a nip for contacting a heating member to pinch and convey a heat recording material. The roller includes a core metal and an elastic layer containing filler. The elastic layer containing the filler includes thermal conductive filler with a length of not less than 0.05 mm and not more than 1 mm with a thermal conductivity &#x3bb;in the longitudinal direction in a range of &#x3bb;&#x2267;500 W/(m&#xb7;k), being dispersed in not less than 5 vol % and not more than 40 vol %. The elastic layer containing the filler has a thermal conductivity &#x3bb;in the longitudinal direction perpendicular to a recording material conveyance direction, of &#x3bb;&#x2267;2.5 W/(m&#xb7;k) and an ASKER-C hardness of the filler is not more than 60 degrees. A solid rubber elastic layer with a thermal conductivity &#x3bb; in a thickness direction of not less than 0.16 W/(m&#xb7;k) and not more than 0.40 W/(m&#xb7;k) is included.

Image heating apparatus and pressure roller used for image heating apparatus

A pressure roller forms a nip for contacting a heating member to pinch and convey a heat recording material. The roller includes a core metal and an elastic layer containing filler. The elastic layer containing the filler includes thermal conductive filler with a length of not less than 0.05 mm and not more than 1 mm and with a thermal conductivity &#x3bb;in the longitudinal direction in a range of &#x3bb;&#x2267;500 W/(m&#xb7;k), being dispersed in not less than 5 vol % and not more than 40 vol %. The elastic layer containing the filler has a thermal conductivity &#x3bb;in the longitudinal direction perpendicular to a recording material conveyance direction, of &#x3bb;&#x2267;2.5 W/(m&#xb7;k) and an ASKER-C hardness of the filler is not more than 60 degrees. A solid rubber elastic layer with a thermal conductivity &#x3bb; in a thickness direction of not less than 0.16 W/(m&#xb7;k) and not more than 0.40 W/(m&#xb7;k) is included.

A pressure member contacts a heating member to form a nip part where a recording material is heated and pinched-conveyed, and includes a first elastic layer and a second elastic layerhaving a higher thermal conductivity than that of the first elastic layer. An elastic layer is formed of a combination of the first elastic layer and the second elastic layer so that the thickness of the second elastic layer at the end portion is thicker than the thickness of the second elastic layer at the center portion in a longitudinal direction perpendicular to a recording material conveyance direction. Accordingly, when using the pressure member to contact the heating member to form the nip part, it is possible to reduce the difference between a center nip width and an end-portion nip width of the nip part.

Image heating apparatus and pressure roller therein having metal core and two elastic layers with different thermal conductivities

The image fixing apparatus includes a heater having a heat generating resistor on a substrate, a heater holder for holding said heater, and a backup roller for forming a nip portion in cooperation with said heater, wherein said heater holder has, in a direction along a short side of said heater, a contact area facing said resistor forming area and coming into contact with said heater, and non-contact areas provided on both sides of the contact area and not coming into contact with said heater, and the contact area has a width equal to or larger than the resistor forming area. With this configuration, it is possible to provide the image fixing apparatus capable of restraining a stress applied to the heater and an image heating apparatus capable of restraining a rise in temperature of a sheet non-feeding portion.

Image fixing apparatus with heater and heater holder contacting the heater

The n image heating apparatus for heating an image formed on a recording material, includes a heater including a substrate, and plural heat generating resistors formed on the substrate along a longitudinal direction thereof, and plural switching elements connected electrically between a power source and the plural heat generating resistors, wherein the plural heat generating resistors include at least two first heat generating resistors driven by a first switching element and at least a second heat generating resistor driven by a second switching element, and the second heat generating resistor is provided between the at least two first heat generating resistors in a direction of a shorter side of the substrate. In this manner there can be provided an image heating apparatus with a heater of an excellent durability, and a heater adapted for use in such apparatus.

Image heating apparatus and heater therefor

An image forming apparatus operating in a double-sided print mode, includes a charger for charging an image carrier, a charge voltage loader for applying a charge voltage to the charger, an image forming device for forming an image on a recording material, and a controller for controlling the charge voltage applied by the charge voltage loader to the charger. When an image is formed on both sides of a plurality of recording materials, the controller changes the charge voltage applied by the charge voltage loader from a first to a second voltage when an image is formed on first and second sides of the recording material in a period in which an image is formed on the recording sheet, and does not change the charge voltage during an interval between a first recording material and a second recording material to the second charge voltage.

Image forming apparatus and printer having a double-sided printing mode

The image forming apparatus includes an image formation unit for forming a toner image on a recording material to be carried by the recording material; a fixing apparatus having a heat-fixing rotation member and a pressure member with an elastic layer which rotate while pressed against each other, the heat-fixing rotor providing heat for heat-fixing treatment of the toner image formed on the recording material as the recording material is introduced into a press-fit nip portion of the rotors and held and transported between the rotors; and temperature adjusting means for adjusting a temperature of the pressure rotor by heating the pressure rotor at least during non-printing time. Thus, the image forming apparatus can achieve, even when the pressure rotor is heated, the best balance between the fixing performance and service life of the pressure rotor under actual use conditions.

Image forming apparatus with a plurality of selectable modes to maintain temperature

The image heating apparatus for heating an image formed on a recording material includes a heater having a substrate and first and second heat generating resistors, most of the region of said first heat generating resistor having smaller resistance value per unit length toward an end in the longitudinal direction of said substrate, and most of the region of said second heat generating resistor having larger resistance value per unit length toward the end part; wherein a safety element can control electrical power supply to said first heat generating resistor and electrical power supply to said second heat generating resistor individually, and operates in response to the heat of said heater to cut off electrical power supply to said first and second heat generating resistors; and wherein only said second heat generating resistor in said first and second heat generating resistors has a high resistance part high resistance part corresponding to said safety element in a part in the longitudinal direction thereof; and consequently, this can provide an image heating apparatus that can cut off electrical power supply quickly when a heater has run away and to provide a heater to be used in this apparatus.

Image heating apparatus and heater used therefor

An image forming apparatus includes a control voltage generation circuit which inputs a primary AC voltage to the primary side of a voltage transformer, generates a control voltage corresponding to a current generated on the secondary side of the voltage transformer in accordance with the primary AC voltage, and controls the primary AC voltage on the basis of the control voltage and a control signal, a current detection circuit which is connected, through a capacitor, to a path which supplies the current generated on the secondary side of the voltage transformer to a charge roller and detects a charge current to charge an image carrier, and a control circuit which determines the control signal on the basis of the relationship between a predetermined control signal (PRICNT) and a current value (Icap) detected by the current detection circuit in accordance with the predetermined control signal and controls the primary AC voltage to be generated by the voltage generation circuit.

Charge voltage control circuit and image forming apparatus which controls a charge voltage based on a discharge current

An image forming apparatus having a fixing apparatus for nipping a recording material bearing an unfixed toner image on the surface thereof by a nip portion between a fixing member and a pressure member and fixing the unfixed toner image on the surface of the recording material has a first temperature detecting element and a second temperature detecting element for detecting the temperatures of the fixing member and the pressure member, respectively, and electric power supplied to a heating portion for heating the fixing member is controlled in conformity with the detected temperature by the first temperature detecting element. When image forming on a plurality of recording materials is to be continuously effected, the conveyance interval of the recording materials is controlled so as to become short when the detected temperature of the pressure member is high, and to become long when the detected temperature of the pressure member is low.

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Mishima, Japan

Hiroaki Sakai