JP5570075B2

JP5570075B2 - Fixing apparatus and image forming apparatus having the same

Info

Publication number: JP5570075B2
Application number: JP2011195713A
Authority: JP
Inventors: 良平 ▲徳▼永
Original assignee: Kyocera Document Solutions Inc
Current assignee: Kyocera Document Solutions Inc
Priority date: 2011-09-08
Filing date: 2011-09-08
Publication date: 2014-08-13
Anticipated expiration: 2031-09-08
Also published as: JP2013057775A

Description

本発明は、複写機、プリンター、ファクシミリ、それらの複合機等の画像形成装置に用いる定着装置及びそれを備えた画像形成装置に関するものである。 The present invention relates to a fixing device used in an image forming apparatus such as a copying machine, a printer, a facsimile machine, or a multifunction machine thereof, and an image forming apparatus including the fixing device.

画像形成装置に用いる定着装置では、加熱部材と加圧部材との間のニップ部に未定着トナー像を担持した記録媒体が送り込まれ、加熱部材による加熱作用によって記録媒体上のトナーが溶融されると同時に、溶融したトナー像に対して加圧部材から加圧作用が付与されることによって記録媒体上にトナー像が定着される。 In a fixing device used in an image forming apparatus, a recording medium carrying an unfixed toner image is fed into a nip portion between a heating member and a pressure member, and the toner on the recording medium is melted by the heating action of the heating member. At the same time, the toner image is fixed on the recording medium by applying a pressure action from the pressure member to the melted toner image.

従来の定着装置では、トナー像が定着された記録媒体が加熱部材に巻き付くのを防ぐために分離爪等からなる分離部材を設けることがある。この分離部材は加熱部材の表面にその先端部を圧接させているので、記録媒体を加熱部材の表面から分離させるときに、トナーや紙粉も剥がされ、剥がされたトナーや紙粉が分離部材に留まることになる。また、加熱部材の表面が分離部材によって傷つけられることになる。これら不具合を防ぐために、分離部材を加熱部材の表面に対して非接触に配設し、記録媒体を加熱部材の表面から分離させているものがある。分離部材の非接触方式では、定着処理前の待機時から加熱部材の昇温、記録媒体の定着処理、そして定着処理後までの一連のサイクルにおいて、加熱部材の表面温度が変化しても、回転する加熱部材の表面が分離部材によって傷つけられることがないように、分離部材が加熱部材の表面に常に当接することがないように構成しておくことが必要である。また、記録媒体を加熱部材の表面から分離させるときには、分離部材と加熱部材の表面とは所定の間隔を有するように構成することが必要である。 In a conventional fixing device, there is a case where a separation member including a separation claw or the like is provided in order to prevent the recording medium on which the toner image is fixed from being wound around the heating member. Since this separation member has the tip thereof pressed against the surface of the heating member, when the recording medium is separated from the surface of the heating member, the toner and paper powder are also peeled off, and the peeled toner and paper powder are removed. Will stay. In addition, the surface of the heating member is damaged by the separation member. In order to prevent these problems, there are some in which the separation member is disposed in a non-contact manner with respect to the surface of the heating member, and the recording medium is separated from the surface of the heating member. In the non-contact method of the separation member, even if the surface temperature of the heating member changes in a series of cycles from the standby time before the fixing process to the temperature rise of the heating member, the fixing process of the recording medium, and after the fixing process, In order to prevent the surface of the heating member to be damaged from being damaged by the separation member, it is necessary that the separation member is not always brought into contact with the surface of the heating member. Further, when separating the recording medium from the surface of the heating member, it is necessary to configure the separation member and the surface of the heating member to have a predetermined interval.

そこで、例えば特許文献１の定着装置では、加熱部材である定着ベルトの表面と分離部材との間隔を一定に保持するための分離部材制御ユニットが設けられている。分離部材制御ユニットは、分離部材を駆動する駆動モーターと、定着ベルトの表面と分離部材との間隔を検知するレーザー測定器と、レーザー測定器からの情報に基づいて分離部材を定着ベルトの表面に対して揺動させる制御回路と、を備えている。駆動モーターで分離部材を揺動させることによって、定着ベルトの表面と分離部材との間隔を一定に保っている。 In view of this, for example, the fixing device disclosed in Patent Document 1 includes a separation member control unit for maintaining a constant distance between the surface of the fixing belt, which is a heating member, and the separation member. The separation member control unit includes a drive motor that drives the separation member, a laser measuring device that detects a distance between the surface of the fixing belt and the separation member, and the separation member on the surface of the fixing belt based on information from the laser measuring device. And a control circuit that swings relative to the control circuit. The separation member is swung by the drive motor, so that the distance between the surface of the fixing belt and the separation member is kept constant.

また、特許文献２の定着装置では、分離部材が揺動可能に支持され、分離部材の長手方向の両端部にはギャップ調整部材が配設されている。ギャップ調整部材が分離部材の先端部から僅かに加熱ローラーの表面側へ突出し、加熱ローラーの表面に当接することで、この突出幅が分離部材と加熱ローラー表面とを所定の間隔とする。加熱ローラーが加熱されることにより、加熱ローラーの表面が径方向外側に熱膨張するが、加熱ローラー表面の径変動に応じてギャップ調整部材が追従して移動し、ギャップ調整部材による突出幅が一定に保持されるので、加熱ローラーの表面と分離部材との間隔を一定に保っている。 Further, in the fixing device of Patent Document 2, the separation member is supported so as to be swingable, and gap adjusting members are disposed at both ends in the longitudinal direction of the separation member. The gap adjusting member slightly protrudes from the front end portion of the separating member toward the surface of the heating roller and comes into contact with the surface of the heating roller, so that the protruding width sets the separating member and the heating roller surface at a predetermined interval. When the heating roller is heated, the surface of the heating roller thermally expands outward in the radial direction, but the gap adjusting member moves following the diameter variation of the heating roller surface, and the protrusion width by the gap adjusting member is constant. Therefore, the distance between the surface of the heating roller and the separation member is kept constant.

通常、記録媒体にトナー像を定着させるため加熱部材に加えられる熱を受けて、定着ベルトを保持する保持ローラーや加熱ローラー等のローラーの外径が熱膨張する。熱膨張する際に、加熱するためのヒーター等の温度勾配がローラーの中央部と端部で異なることや、ローラーの端部は外気温の影響を受けやすい等の理由により、加熱部材表面の中央部と端部とでは膨張量が異なっている。 Usually, the outer diameter of a roller such as a holding roller or a heating roller that holds the fixing belt is thermally expanded by receiving heat applied to the heating member to fix the toner image on the recording medium. When the thermal expansion, the temperature gradient of the heater, etc. for heating is different between the central part and the end part of the roller, or the end part of the roller is easily affected by the outside air temperature. The expansion amount differs between the portion and the end portion.

このために、上記特許文献１の定着装置では、例えばレーザー測定器が定着ベルトの端部側において、定着ベルトの表面と分離部材との間隔を検知している場合、定着処理の一連のサイクルにおいて、加熱部材が昇温すると、レーザー測定器の測定結果に基づいて加熱部材の表面と分離部材との間隔が設定される。定着ベルトの端部側は、定着ベルトの表面と分離部材との間隔を常に一定に保たれている。しかし、定着ベルトの中央部は、その端部に比べて膨張量が大きいために、定着ベルトの表面と分離部材との間隔が小さくなる。その結果、分離部材が定着ベルト表面の中央部に当接すると、定着ベルトの表面を傷つけることになる。 For this reason, in the fixing device disclosed in Patent Document 1, for example, when the laser measuring device detects the distance between the surface of the fixing belt and the separation member on the end side of the fixing belt, in a series of fixing processing cycles. When the temperature of the heating member rises, the distance between the surface of the heating member and the separation member is set based on the measurement result of the laser measuring instrument. On the end side of the fixing belt, the distance between the surface of the fixing belt and the separation member is always kept constant. However, since the central portion of the fixing belt has a larger expansion amount than the end portion thereof, the distance between the surface of the fixing belt and the separating member is reduced. As a result, when the separating member comes into contact with the center portion of the fixing belt surface, the surface of the fixing belt is damaged.

また上記特許文献２の定着装置では、定着処理の一連のサイクルにおいて、加熱ローラーが昇温すると、加熱ローラーの端部側は、ギャップ調整部材によって加熱ローラーの表面と分離部材との間隔を常に一定に保たれているが、加熱ローラーの中央部は、その端部に比べて膨張量が大きいために、加熱ローラーの表面と分離部材との間隔が小さくなる。その結果、分離部材が加熱ローラー表面の中央部に当接すると、加熱ローラーの表面を傷つけることになる。 In the fixing device disclosed in Patent Document 2, when the heating roller is heated in a series of fixing processes, the gap between the end of the heating roller and the surface of the heating roller is always constant by the gap adjusting member. However, since the expansion amount of the center portion of the heating roller is larger than that of the end portion thereof, the distance between the surface of the heating roller and the separation member is reduced. As a result, when the separating member comes into contact with the center portion of the surface of the heating roller, the surface of the heating roller is damaged.

そこで、特許文献３の定着装置では、加熱ローラーの表面と分離部材との間隔を一定に保持するための当接部材が設けられ、当接部材は、分離部材と一体に設けられ、端部の定着領域外で加熱ローラーの表面に当接している。そして、加圧ローラーは定着領域を含む長手方向の長さを有し、一方、加熱ローラーは加圧ローラーに比べて長手方向に長く構成されている。このように加熱ローラーを端部方向へ延長することで、当接部材に当接する加熱ローラーの表面部分と加熱ローラー表面の中央部とで、加熱ローラーの熱による膨張量の差を小さくし、その結果、加熱ローラーの表面と分離部材との間隔の変動を小さくしている。 Therefore, in the fixing device of Patent Document 3, a contact member is provided to keep the distance between the surface of the heating roller and the separation member constant, and the contact member is provided integrally with the separation member, It is in contact with the surface of the heating roller outside the fixing area. The pressure roller has a length in the longitudinal direction including the fixing region, while the heating roller is configured to be longer in the longitudinal direction than the pressure roller. By extending the heating roller in the end direction in this way, the difference in expansion amount due to the heat of the heating roller is reduced between the surface portion of the heating roller that contacts the contact member and the central portion of the surface of the heating roller. As a result, the variation in the distance between the surface of the heating roller and the separation member is reduced.

特開２００８−１９７５３５号公報（段落［００２４］、［００２５］、第１図）JP 2008-197535 A (paragraphs [0024], [0025], FIG. 1) 特開２００８−１９７２３７号公報（段落［００１４］〜［００２０］、第５図、第６図）JP 2008-197237 A (paragraphs [0014] to [0020], FIGS. 5 and 6) 特開２００９−１４７７１号公報（段落［０００７］、［０００８］、第３図）Japanese Patent Laying-Open No. 2009-14771 (paragraphs [0007] and [0008], FIG. 3)

しかしながら、上述した特許文献３の定着装置では、加熱ローラーが長手方向に長くなることで、定着装置の大型化やコストアップが避けられないという不都合があった。 However, in the fixing device of Patent Document 3 described above, there is a problem in that an increase in size and cost of the fixing device cannot be avoided because the heating roller becomes longer in the longitudinal direction.

本発明は、上記のような課題を解決するためになされたものであり、大型化やコストアップすることなく、また、加熱部材の表面温度が変化しても、分離部材によって加熱部材の表面が傷つけられることがなく、記録媒体を加熱部材から良好に分離する定着装置及びそれを備えた画像形成装置を提供することを目的とする。 The present invention has been made to solve the above-described problems, and without increasing the size and cost, and even if the surface temperature of the heating member changes, the surface of the heating member is separated by the separation member. It is an object of the present invention to provide a fixing device that satisfactorily separates a recording medium from a heating member without being damaged, and an image forming apparatus including the same.

上記目的を達成するために第１の発明は、加熱部材と該加熱部材に圧接される加圧部材とにより形成されるニップ部で未定着トナー像を担持した記録媒体を挟持して、記録媒体上の未定着トナー像を溶融定着する定着装置において、前記加熱部材の表面に対して所定の間隔を隔てた状態にて前記加熱部材の表面から定着処理後の記録媒体を分離させる分離部材と、前記加熱部材の長手方向端部の表面温度を検知する温度検知部と、前記分離部材の長手方向の両端部にて前記加熱部材の表面に対する前記分離部材の間隔を可変にする間隔調整部と、を備え、前記間隔調整部は、検知された表面温度に基づいて前記分離部材を揺動させ、表面温度が定着可能温度であるとき、前記加熱部材の表面と分離部材との間隔が所定の間隔となるように前記分離部材を移動させ、表面温度が定着可能温度より低いとき、前記加熱部材の表面と分離部材との間隔が、前記加熱部材の端部と中央部との熱膨張量の差より大きくなるように前記分離部材を移動させることを特徴としている。 In order to achieve the above object, a first aspect of the present invention is a recording medium in which a recording medium carrying an unfixed toner image is sandwiched by a nip formed by a heating member and a pressure member pressed against the heating member. In the fixing device for fusing and fixing the unfixed toner image on the upper side, a separation member for separating the recording medium after the fixing process from the surface of the heating member in a state of being spaced apart from the surface of the heating member; A temperature detection unit that detects a surface temperature of a longitudinal end portion of the heating member; and a spacing adjustment unit that varies a spacing of the separation member with respect to the surface of the heating member at both longitudinal end portions of the separation member; And the interval adjusting unit swings the separation member based on the detected surface temperature, and when the surface temperature is a fixing possible temperature, the interval between the surface of the heating member and the separation member is a predetermined interval. Said to be When the separation member is moved and the surface temperature is lower than the fixable temperature, the distance between the surface of the heating member and the separation member is larger than the difference in thermal expansion between the end portion and the central portion of the heating member. The separation member is moved.

また、第２の発明では、上記の定着装置において、前記温度検知部は、前記加熱部材の表面に対向して配設され、検知した温度が定着可能温度であるとき前記加熱部材の表面から離間する第１の方向に変形し、検知した温度が定着可能温度より低いとき前記加熱部材の表面に近接する第２の方向に変形するセンサー部であり、前記間隔調整部は、前記分離部材を揺動可能に支持する支持部材と、前記分離部材の前記加熱部材に近接する端部から前記加熱部材の表面側に突出して配設され前記分離部材と前記加熱部材とを所定の間隔に保持する突出部材と、該突出部材の先端に変形可能に支持された前記センサー部と、を有し、前記センサー部が第１の方向に変形したとき前記突出部材が前記加熱部材の表面に当接するとともに、前記センサー部が第２の方向に変形したとき前記センサー部が前記加熱部材の表面に当接することを特徴としている。 According to a second aspect of the present invention, in the fixing device, the temperature detection unit is disposed to face the surface of the heating member, and is separated from the surface of the heating member when the detected temperature is a fixable temperature. A sensor unit that deforms in a first direction and deforms in a second direction adjacent to the surface of the heating member when the detected temperature is lower than the fixable temperature, and the interval adjustment unit swings the separation member. A support member that is movably supported, and a protrusion that protrudes from the end of the separation member that is close to the heating member to the surface side of the heating member and holds the separation member and the heating member at a predetermined interval. And a sensor part supported in a deformable manner at the tip of the projecting member, and when the sensor part is deformed in the first direction, the projecting member contacts the surface of the heating member, Sensor There has been characterized in that the sensor unit when deformed in a second direction to contact with the surface of the heating member.

また、第３の発明では、上記の定着装置において、前記間隔調整部は、前記分離部材を揺動可能に支持する支持部材と、前記分離部材の前記加熱部材に近接する端部から前記加熱部材の表面側に突出して配設され前記分離部材と前記加熱部材とを所定の間隔に保持する突出部材と、前記分離部材を揺動させる作動部と、を有し、前記作動部は、前記温度検知部により検知された前記加熱部材の表面温度が定着可能温度より低いとき、前記突出部材を前記加熱部材の表面から離間した位置に移動させ、前記加熱部材の表面温度が定着可能温度であるとき、前記突出部材を前記加熱部材の表面に当接する位置に移動させることを特徴としている。 According to a third aspect of the present invention, in the above fixing device, the gap adjusting unit includes a support member that supports the separation member in a swingable manner, and an end portion of the separation member that is close to the heating member. A projecting member that projects from the front surface side and holds the separation member and the heating member at a predetermined interval, and an operation unit that swings the separation member, When the surface temperature of the heating member detected by the detection unit is lower than the fixable temperature, the projecting member is moved to a position separated from the surface of the heating member, and the surface temperature of the heating member is the fixable temperature. The projecting member is moved to a position in contact with the surface of the heating member.

また、第４の発明では、上記の定着装置において、前記作動部は、前記突出部材が前記加熱部材の表面から離間する方向に前記分離部材を押圧するソレノイドと、前記突出部材が前記加熱部材の表面に近づく方向に前記分離部材を付勢するバネ部材と、を有することを特徴としている。 According to a fourth aspect of the present invention, in the above fixing device, the operating unit includes a solenoid that presses the separation member in a direction in which the protruding member is separated from the surface of the heating member, and the protruding member is the heating member. And a spring member that urges the separation member in a direction approaching the surface.

また、第５の発明では、上記の構成の定着装置を備えた画像形成装置である。 According to a fifth aspect of the invention, there is provided an image forming apparatus including the fixing device having the above-described configuration.

定着処理を行うために加熱部材が昇温すると加熱部材の表面が膨張する。加熱部材の表面温度が定着可能温度に到達するまでは、加熱部材の表面が膨張する際に、加熱部材の中央部が端部に比べて大きく膨張する。第１の発明によれば、定着処理前において加熱部材の表面温度が定着可能温度より低いとき、加熱部材の表面と分離部材との間隔が、加熱部材の端部と中央部との熱膨張量の差より大きくなるように、間隔調整部が分離部材を移動させるために、分離部材が加熱部材の表面に当接することがなく、分離部材によって加熱部材の表面が傷つけられることがない。そして、加熱部材の表面温度が定着可能温度であるとき、加熱部材の端部と中央部が略同じ温度となり、ニップ部にて記録媒体の定着処理が行われる。次に分離部材によって記録部材が加熱部材の表面から分離されるとき、定着処理の直後であるために、加熱部材の表面温度が定着可能温度であり、間隔調整部によって、加熱部材の表面と分離部材との間隔が所定の間隔に保持されており、分離部材によって記録部材が加熱部材の表面から良好に分離される。 When the heating member rises in temperature to perform the fixing process, the surface of the heating member expands. Until the surface temperature of the heating member reaches the fixable temperature, when the surface of the heating member expands, the central portion of the heating member expands more than the end portion. According to the first invention, when the surface temperature of the heating member is lower than the fixable temperature before the fixing process, the distance between the surface of the heating member and the separation member is the amount of thermal expansion between the end portion and the central portion of the heating member. Since the distance adjusting unit moves the separation member so as to be larger than the difference, the separation member does not contact the surface of the heating member, and the surface of the heating member is not damaged by the separation member. When the surface temperature of the heating member is a fixable temperature, the end portion and the central portion of the heating member become substantially the same temperature, and the fixing process of the recording medium is performed at the nip portion. Next, when the recording member is separated from the surface of the heating member by the separation member, the surface temperature of the heating member is the fixing possible temperature because it is immediately after the fixing process, and is separated from the surface of the heating member by the interval adjusting unit. The distance from the member is maintained at a predetermined distance, and the recording member is favorably separated from the surface of the heating member by the separation member.

本発明の第１実施形態に係る定着装置を備えた画像形成装置の概略構成を示す図1 is a diagram illustrating a schematic configuration of an image forming apparatus including a fixing device according to a first embodiment of the present invention. 第１実施形態に係る定着装置を示す側面断面図1 is a side sectional view showing a fixing device according to a first embodiment. 第１実施形態に係る定着装置の間隔調整部を示す側面図FIG. 3 is a side view showing the interval adjusting unit of the fixing device according to the first embodiment. 第１実施形態に係る定着装置の間隔調整部の配置を示す平面図FIG. 3 is a plan view showing the arrangement of the interval adjustment unit of the fixing device according to the first embodiment. 第１実施形態に係る定着装置の間隔調整部を示す断面図Sectional drawing which shows the space | interval adjustment part of the fixing device which concerns on 1st Embodiment. 第１実施形態に係る定着装置の定着処理前の間隔調整部を示す断面図Sectional drawing which shows the space | interval adjustment part before the fixing process of the fixing device which concerns on 1st Embodiment. 第２実施形態に係る定着装置を示す側面図Side view showing a fixing device according to a second embodiment. 第２実施形態に係る定着装置の間隔調整部を示す側面図The side view which shows the space | interval adjustment part of the fixing device which concerns on 2nd Embodiment.

以下に本発明の実施形態について図面を参照して説明するが、本発明は、この実施形態に限定されない。また発明の用途やここで示す用語等はこれに限定されるものではない。 Embodiments of the present invention will be described below with reference to the drawings, but the present invention is not limited to these embodiments. Further, the use of the invention and the terms shown here are not limited thereto.

（第１実施形態）
図１は、本発明の実施形態に係る定着装置を備えた画像形成装置の概略構成を示す図である。画像形成装置１は、その下部に配設された給紙部２と、この給紙部２の側方に配設された用紙搬送部３と、この用紙搬送部３の上方に配設された画像形成部４と、この画像形成部４よりも排出側に配設された定着装置５と、画像形成部４及び定着装置５の上方に配設された画像読取部６とを備えている。 (First embodiment)
FIG. 1 is a diagram illustrating a schematic configuration of an image forming apparatus including a fixing device according to an embodiment of the present invention. The image forming apparatus 1 is provided with a sheet feeding unit 2 disposed in a lower portion thereof, a sheet conveying unit 3 disposed on a side of the sheet feeding unit 2, and an upper side of the sheet conveying unit 3. The image forming unit 4 includes a fixing device 5 disposed on the discharge side of the image forming unit 4, and an image reading unit 6 disposed above the image forming unit 4 and the fixing device 5.

給紙部２は、記録媒体である用紙９を収容する複数の給紙カセット７を備えており、給紙ローラー８の回転により、複数の給紙カセット７のうち選択された給紙カセット７から用紙９を１枚ずつ用紙搬送部３に送り出す。 The paper feed unit 2 includes a plurality of paper feed cassettes 7 that store paper 9 that is a recording medium. The paper 9 is sent to the paper transport unit 3 one by one.

用紙搬送部３に送られた用紙９は、用紙搬送経路１０を経由して画像形成部４に向けて搬送される。画像形成部４は、電子写真プロセスによって、用紙９にトナー像を形成するものであり、図１の矢印方向に回転可能に支持された感光体１１と、この感光体１１の周囲にその回転方向に沿って、帯電部１２、露光部１３、現像部１４、転写部１５、クリーニング部１６、及び除電部１７を備えている。 The paper 9 sent to the paper transport unit 3 is transported toward the image forming unit 4 via the paper transport path 10. The image forming unit 4 forms a toner image on a sheet 9 by an electrophotographic process. The image forming unit 4 is a photoconductor 11 supported so as to be rotatable in the direction of an arrow in FIG. A charging unit 12, an exposure unit 13, a developing unit 14, a transfer unit 15, a cleaning unit 16, and a charge eliminating unit 17 are provided.

帯電部１２は、高電圧を印加される帯電ワイヤーを備えており、この帯電ワイヤーからのコロナ放電によって感光体１１表面に所定電位を与えると、感光体１１表面が一様に帯電させられる。そして、画像読取部６によって読み取られた原稿の画像データに基づく光が、露光部１３により感光体１１に照射されると、感光体１１の表面電位が選択的に減衰され、感光体１１表面に静電潜像が形成される。 The charging unit 12 includes a charging wire to which a high voltage is applied. When a predetermined potential is applied to the surface of the photoconductor 11 by corona discharge from the charging wire, the surface of the photoconductor 11 is uniformly charged. Then, when light based on the image data of the original read by the image reading unit 6 is irradiated to the photoconductor 11 by the exposure unit 13, the surface potential of the photoconductor 11 is selectively attenuated, and the surface of the photoconductor 11 is irradiated. An electrostatic latent image is formed.

次いで、現像部１４が感光体１１表面の静電潜像を現像し、感光体１１表面にトナー像が形成される。このトナー像が転写部１５によって感光体１１と転写部１５との間に供給される用紙９に転写される。 Next, the developing unit 14 develops the electrostatic latent image on the surface of the photoconductor 11, and a toner image is formed on the surface of the photoconductor 11. This toner image is transferred by the transfer unit 15 to the sheet 9 supplied between the photoconductor 11 and the transfer unit 15.

トナー像が転写された用紙９は、画像形成部４の用紙搬送方向の下流側に配置された定着装置５に向けて搬送される。定着装置５では用紙９が加熱加圧され、用紙９上にトナー像が溶融定着される。次いで、トナー像が定着された用紙９は、排出ローラー対２０によって排出トレイ２１上に排出される。 The sheet 9 on which the toner image has been transferred is conveyed toward the fixing device 5 disposed downstream of the image forming unit 4 in the sheet conveying direction. In the fixing device 5, the paper 9 is heated and pressed, and the toner image is melted and fixed on the paper 9. Next, the sheet 9 on which the toner image is fixed is discharged onto the discharge tray 21 by the discharge roller pair 20.

転写部１５による用紙９へのトナー像の転写後、感光体１１表面に残留しているトナーは、クリーニング部１６により除去され、また感光体１１表面の残留電荷は除電部１７により除去される。そして、感光体１１は帯電部１２によって再び帯電され、以下同様にして画像形成が行われる。 After the transfer of the toner image onto the paper 9 by the transfer unit 15, the toner remaining on the surface of the photoconductor 11 is removed by the cleaning unit 16, and the residual charge on the surface of the photoconductor 11 is removed by the charge eliminating unit 17. Then, the photosensitive member 11 is charged again by the charging unit 12, and image formation is performed in the same manner.

定着装置５は図２に示すように構成される。図２は定着装置を概略的に示す側面断面図である。 The fixing device 5 is configured as shown in FIG. FIG. 2 is a side sectional view schematically showing the fixing device.

定着装置５は、電磁誘導加熱方式の熱源を用いた定着方式であり、加熱部材である定着ベルト２６と、加圧部材である加圧ローラー１９と、定着ベルト２６を一体的に取り付けた定着ローラー１８と、定着ベルト２６を加熱する誘導加熱部３０と、定着処理後の用紙９を定着ベルト２６から分離する分離部材５１と、を備える。加圧ローラー１９及び定着ローラー１８は定着装置５のハウジング（図略）の長手方向に回転可能に支持され、誘導加熱部３０はハウジングに固定支持され、また、分離部材５１はハウジングに揺動可能に支持される。 The fixing device 5 is a fixing method using a heat source of an electromagnetic induction heating method, and a fixing belt 26 as a heating member, a pressure roller 19 as a pressure member, and a fixing roller to which the fixing belt 26 is integrally attached. 18, an induction heating unit 30 that heats the fixing belt 26, and a separation member 51 that separates the paper 9 after the fixing process from the fixing belt 26. The pressure roller 19 and the fixing roller 18 are rotatably supported in the longitudinal direction of the housing (not shown) of the fixing device 5, the induction heating unit 30 is fixedly supported on the housing, and the separation member 51 is swingable on the housing. Supported by

定着ベルト２６は、無端状の耐熱ベルトであり、内周側から順に、電鋳ニッケルからなる誘導発熱層２６ａと、シリコーンゴム等からなる弾性層２６ｂと、フッ素樹脂等からなりニップ部Ｎで未定着トナー像を溶融定着する際の離型性を向上させる離型層２６ｃと、が積層されて構成される。 The fixing belt 26 is an endless heat-resistant belt, and in order from the inner peripheral side, an induction heating layer 26a made of electroformed nickel, an elastic layer 26b made of silicone rubber, etc., and made of fluororesin etc. A release layer 26c that improves the releasability at the time of melting and fixing the toner image is laminated.

定着ローラー１８は、定着ベルト２６を一体回転可能とするために、定着ベルト２６の内周面を張架している。例えば、ステンレス鋼の芯金１８ａ上にシリコーンゴム製の弾性層１８ｂを有し、弾性層１８ｂは定着ベルト２６を張架している。 The fixing roller 18 stretches the inner peripheral surface of the fixing belt 26 so that the fixing belt 26 can rotate integrally. For example, an elastic layer 18b made of silicone rubber is provided on a stainless steel core 18a, and the fixing belt 26 is stretched over the elastic layer 18b.

加圧ローラー１９は、ステンレス鋼等の円筒型の芯金１９ａと、芯金１９ａ上に形成される例えばシリコーンゴム製の弾性層１９ｂと、弾性層１９ｂの表面を覆うフッ素樹脂等からなる離型層１９ｃと、を備える。また、加圧ローラー１９は図示しないモーター等の駆動源によって回転駆動させられ、加圧ローラー１９の回転によって定着ベルト２６は従動回転する。加圧ローラー１９と定着ベルト２６との圧接する部分にニップ部Ｎが形成され、ニップ部Ｎでは、搬送される用紙９上の未定着トナー像を加熱及び加圧し用紙９上にトナー像を定着する。 The pressure roller 19 includes a cylindrical cored bar 19a such as stainless steel, an elastic layer 19b made of, for example, silicone rubber formed on the cored bar 19a, and a mold release made of a fluororesin or the like covering the surface of the elastic layer 19b. A layer 19c. The pressure roller 19 is rotated by a drive source such as a motor (not shown), and the fixing belt 26 is driven to rotate by the rotation of the pressure roller 19. A nip portion N is formed at a portion where the pressure roller 19 and the fixing belt 26 are pressed against each other. The nip portion N heats and presses an unfixed toner image on the paper 9 being transported to fix the toner image on the paper 9. To do.

誘導加熱部３０は、コイル３７と、ボビン３８と、磁性体コア３９とを備え、電磁誘導により定着ベルト２６を加熱するものである。誘導加熱部３０は、定着ベルト２６の幅方向（図２の紙面の表面から裏面方向）に延びて、定着ベルト２６の外周の略半分を囲うように定着ベルト２６に対向して配設される。 The induction heating unit 30 includes a coil 37, a bobbin 38, and a magnetic core 39, and heats the fixing belt 26 by electromagnetic induction. The induction heating unit 30 extends in the width direction of the fixing belt 26 (from the front surface to the back surface in FIG. 2), and is disposed to face the fixing belt 26 so as to surround substantially half of the outer periphery of the fixing belt 26. .

コイル３７は、定着ベルト２６の幅方向に沿ってループ状に複数回巻回してボビン３８に取り付けられる。またコイル３７は、図示しない電源に接続され、電源から供給される高周波電流により磁界を発生させる。コイル３７の磁界によって磁性体コア３９から発せられる磁束は、図２の紙面に平行な方向に導かれ、定着ベルト２６の誘導発熱層２６ａを貫通する。誘導発熱層２６ａの磁束の周りには渦電流が生じ、渦電流が流れると、誘導発熱層２６ａの電気抵抗によってジュール熱が発生し、その結果、定着ベルト２６が発熱することになる。 The coil 37 is attached to the bobbin 38 by being wound a plurality of times in a loop shape along the width direction of the fixing belt 26. The coil 37 is connected to a power source (not shown) and generates a magnetic field by a high-frequency current supplied from the power source. A magnetic flux generated from the magnetic core 39 by the magnetic field of the coil 37 is guided in a direction parallel to the paper surface of FIG. 2 and penetrates the induction heating layer 26 a of the fixing belt 26. An eddy current is generated around the magnetic flux of the induction heat generation layer 26a. When the eddy current flows, Joule heat is generated by the electric resistance of the induction heat generation layer 26a, and as a result, the fixing belt 26 generates heat.

分離部材５１は、定着処理後の用紙９を定着ベルト２６の表面から分離するものであり、ニップ部Ｎに対して定着ベルト２６の回転方向の下流側近傍に配設され、その先端部が定着ベルト２６の表面に対して所定の間隔を隔てて配置される。また、分離部材５１は、定着ベルト２６の幅方向に延びる横長の板材からなる。尚、分離部材５１は、複数の分離爪からなり、定着ベルト２６の幅方向に延びる取り付け部材に複数個並べて設けた構成としてもよい。 The separation member 51 separates the sheet 9 after the fixing process from the surface of the fixing belt 26, and is disposed in the vicinity of the nip portion N on the downstream side in the rotation direction of the fixing belt 26, and its leading end is fixed. The belt 26 is disposed at a predetermined interval with respect to the surface of the belt 26. The separating member 51 is made of a horizontally long plate material that extends in the width direction of the fixing belt 26. Note that the separation member 51 may include a plurality of separation claws, and a plurality of separation members 51 may be provided side by side on an attachment member extending in the width direction of the fixing belt 26.

定着ベルト２６が加熱され定着可能温度になると、ニップ部Ｎで挟持された用紙９が加熱されるとともに、加圧ローラー１９にて加圧されることにより、用紙９上の粉体状態のトナーが溶融定着される。定着処理後の用紙９は、定着ベルト２６の表面に密着して搬送されるが、分離部材５１によって定着ベルト２６の表面から分離され、定着装置５の下流側に搬送される。分離部材５１が定着ベルト２６の表面から所定の間隔だけ隔てた状態で定着ベルト２６から用紙９を分離するために、定着ベルト２６の表面は分離部材５１によって傷つけられることがない。 When the fixing belt 26 is heated and reaches a fixing possible temperature, the paper 9 sandwiched by the nip portion N is heated and pressed by the pressure roller 19, whereby the powdery toner on the paper 9 is heated. Melt and fix. The sheet 9 after the fixing process is conveyed in close contact with the surface of the fixing belt 26, but is separated from the surface of the fixing belt 26 by the separating member 51 and conveyed downstream of the fixing device 5. Since the separation member 51 separates the sheet 9 from the fixing belt 26 with a predetermined distance from the surface of the fixing belt 26, the surface of the fixing belt 26 is not damaged by the separation member 51.

分離部材５１は、間隔調整部６０によって定着ベルト２６表面との間隔を可変にされる。間隔調整部６０の構成を図３〜図６に示す。図３は間隔調整部６０を示す側面図であり、図４は間隔調整部６０の配置を示す平面図である。図５、図６は、夫々図３のＸ−Ｘ面における間隔調整部６０の断面図であり、図５は定着処理時及び定着処理直後の間隔調整部を６０示し、図６は定着処理前の間隔調整部６０を示すものである。 The distance between the separation member 51 and the surface of the fixing belt 26 is made variable by the distance adjusting unit 60. The structure of the space | interval adjustment part 60 is shown in FIGS. FIG. 3 is a side view showing the interval adjusting unit 60, and FIG. 4 is a plan view showing the arrangement of the interval adjusting unit 60. 5 and 6 are cross-sectional views of the interval adjusting unit 60 in the XX plane of FIG. 3, respectively. FIG. 5 shows the interval adjusting unit 60 during and immediately after the fixing process, and FIG. The space | interval adjustment part 60 is shown.

図３に示すように、分離部材５１は、支持部材６１によって揺動可能に支持され、バネ部材６２によって定着ベルト２６側に付勢され、そして、その先端部５１ｂにて用紙９を定着ベルト２６の表面から分離させる。 As shown in FIG. 3, the separation member 51 is supported by a support member 61 so as to be swingable, and is urged toward the fixing belt 26 by a spring member 62, and the sheet 9 is fed to the fixing belt 26 by the tip 51b. Separate from the surface.

具体的には、分離部材５１には、そのフランジ部に形成された嵌装孔５１ａと、定着ベルト２６の表面に対向する先端部５１ｂとが設けられる。嵌装孔５１ａは分離部材５１の長手方向の両端部に形成される。嵌装孔５１ａには、図示しないハウジングに固設された支持部材６１が係合し、分離部材５１は支持部材６１の回りで回動可能となる。バネ部材６２は、引っ張りコイルスプリング等からなり、その一端部がハウジングに固設され、その他端部が分離部材５１に固設される。 Specifically, the separation member 51 is provided with a fitting hole 51 a formed in the flange portion and a tip portion 51 b that faces the surface of the fixing belt 26. The fitting holes 51 a are formed at both ends of the separating member 51 in the longitudinal direction. A support member 61 fixed to a housing (not shown) is engaged with the fitting hole 51 a, so that the separation member 51 can rotate around the support member 61. The spring member 62 is formed of a tension coil spring or the like, and one end thereof is fixed to the housing, and the other end is fixed to the separation member 51.

分離部材５１の先端部５１ｂには突出部材６４が設けられる。突出部材６４は、分離部材５１の先端部５１ｂに一体に取り付けられ、バネ部材６２の付勢力によって定着ベルト２６の表面に当接することが可能である。突出部材６４の当接部６４ａが定着ベルト２６の表面に当接することによって、分離部材５１と定着ベルト２６の表面との間隔がＤに設定される。この所定の間隔Ｄだけ定着ベルト２６の表面から離間した状態で、分離部材５１は定着ベルト２６の表面から用紙９を分離する。尚、支持部材６１とバネ部材６２と突出部材６４及び後述するセンサー部７１（図５参照）は、間隔調整部６０を構成している。 A protruding member 64 is provided at the distal end portion 51 b of the separating member 51. The protruding member 64 is integrally attached to the distal end portion 51 b of the separating member 51, and can come into contact with the surface of the fixing belt 26 by the urging force of the spring member 62. When the contact portion 64 a of the protruding member 64 contacts the surface of the fixing belt 26, the distance between the separation member 51 and the surface of the fixing belt 26 is set to D. The separation member 51 separates the sheet 9 from the surface of the fixing belt 26 while being separated from the surface of the fixing belt 26 by the predetermined distance D. Note that the support member 61, the spring member 62, the protruding member 64, and a sensor unit 71 (see FIG. 5), which will be described later, constitute an interval adjusting unit 60.

図４に示すように、突出部材６４は分離部材５１の長手方向の両端部に設けられる。定着ベルト２６上には、定着処理される用紙９の最大サイズ用紙の定着処理領域Ａが形成されるが、突出部材６４は最大サイズ用紙の定着処理領域Ａの外側にて定着ベルト２６の表面に当接している。 As shown in FIG. 4, the protruding members 64 are provided at both ends of the separating member 51 in the longitudinal direction. On the fixing belt 26, a fixing processing area A for the maximum size paper of the paper 9 to be fixed is formed, but the protruding member 64 is on the surface of the fixing belt 26 outside the fixing processing area A for the maximum size paper. It is in contact.

図５に示すように、突出部材６４は、分離部材５１に取り付けられる基部６４ｃと、定着ベルト２６の表面に当接可能である当接部６４ａと、温度検知部であるセンサー部７１をスナップ変形可能に支持するセンサー支持部６４ｂとを、有する。 As shown in FIG. 5, the protruding member 64 snap-deforms a base portion 64 c attached to the separation member 51, a contact portion 64 a that can contact the surface of the fixing belt 26, and a sensor portion 71 that is a temperature detection portion. And a sensor support portion 64b that supports the sensor.

センサー支持部６４ｂは、当接部６４ａの上側に直方体状の空間を形成し、その空間の下側の周縁を開放する下側フランジ部と上側の周縁を開放する上側フランジ部とを有する。センサー支持部６４ｂは、直方体状空間内にセンサー部７１を収納し、上側及び下側のフランジ部にてセンサー部７１を支持している。 The sensor support part 64b forms a rectangular parallelepiped space above the contact part 64a, and has a lower flange part that opens the lower periphery of the space and an upper flange part that opens the upper periphery. The sensor support portion 64b houses the sensor portion 71 in a rectangular parallelepiped space, and supports the sensor portion 71 with upper and lower flange portions.

センサー部７１は、長方形状のバイメタルからなり感熱面を下側にして湾曲して形成される。即ち、センサー部７１の感熱面は、定着ベルト２６の表面に近接して対向する。定着ベルト２６の表面温度が例えば１７０℃の定着可能温度である場合、センサー部７１の感熱面がその温度を検知し、その検知温度に基づいて、センサー部７１は図５に示すように上側へ凸状に湾曲する。定着ベルト２６の表面が定着可能温度より低い場合、センサー部７１の感熱面がその温度を検知し、その検知温度に基づいて、センサー部７１は、図６に示すように下側へ凸状に湾曲する。このようにセンサー部７１は、定着可能温度を境として上側或いは下側へ凸状となるようにスナップ変形する。尚、センサー部７１は円板状のバイメタルを湾曲させて構成してもよい。この場合には、センサー支持部６４は、センサー部７１の外縁に合わせて円筒状の空間を形成することになる。 The sensor unit 71 is made of a rectangular bimetal and is formed with a heat-sensitive surface facing downward. That is, the heat-sensitive surface of the sensor unit 71 is opposed to the surface of the fixing belt 26 in the vicinity. When the surface temperature of the fixing belt 26 is a fixing possible temperature of, for example, 170 ° C., the heat-sensitive surface of the sensor unit 71 detects the temperature, and the sensor unit 71 moves upward as shown in FIG. 5 based on the detected temperature. Curves in a convex shape. When the surface of the fixing belt 26 is lower than the fixable temperature, the thermosensitive surface of the sensor unit 71 detects the temperature, and based on the detected temperature, the sensor unit 71 is convex downward as shown in FIG. Bend. In this manner, the sensor unit 71 is snap-deformed so as to protrude upward or downward with the fixing temperature as a boundary. The sensor unit 71 may be configured by bending a disc-shaped bimetal. In this case, the sensor support portion 64 forms a cylindrical space in accordance with the outer edge of the sensor portion 71.

センサー部７１が上側へ凸状に変形したとき（図５の状態）、センサー部７１の感熱面に対して反対側の上面がセンサー支持部６４ｂの上側フランジ部に当接した状態で、センサー部７１がセンサー支持部６４ｂに保持されている。この状態では、突出部材６４の当接部６４ａが定着ベルト２６の表面に当接し、定着ベルト２６の表面と分離部材５１との間隔は、所定の間隔Ｄに保持される。また、定着ベルト２６の表面温度は、定着処理領域Ａ（図４参照）の端部から中央部において略定着可能温度となり、ニップ部Ｎにて用紙９の定着処理が行われる。次に、分離部材５１によって用紙９が定着ベルト２６の表面から分離されるとき、定着処理の直後であるために、定着ベルト２６の表面温度が定着可能温度であり、突出部材６４によって、定着ベルト２６の表面と分離部材５１との間隔が所定の間隔Ｄに保持されており、分離部材５１によって用紙９が定着ベルト２６の表面から良好に分離される。 When the sensor unit 71 is deformed in a convex shape upward (state shown in FIG. 5), the sensor unit 71 is in a state in which the upper surface opposite to the heat-sensitive surface of the sensor unit 71 is in contact with the upper flange portion of the sensor support unit 64b. 71 is held by the sensor support 64b. In this state, the contact portion 64a of the protruding member 64 contacts the surface of the fixing belt 26, and the distance between the surface of the fixing belt 26 and the separation member 51 is maintained at a predetermined distance D. Further, the surface temperature of the fixing belt 26 becomes substantially fixable temperature from the end portion to the center portion of the fixing processing area A (see FIG. 4), and the fixing processing of the sheet 9 is performed at the nip portion N. Next, when the sheet 9 is separated from the surface of the fixing belt 26 by the separating member 51, immediately after the fixing process, the surface temperature of the fixing belt 26 is the fixing possible temperature, and the fixing member 64 The distance between the surface of 26 and the separating member 51 is maintained at a predetermined distance D, and the sheet 9 is favorably separated from the surface of the fixing belt 26 by the separating member 51.

一方、図６に示すように、センサー部７１が下側へ凸状に変形したとき、センサー部７１の感熱面がセンサー支持部６４ｂの下側フランジ部に当接し、センサー部７１の感熱面の凸状の先端部が突出部材６４の当接部６４ａから下側に突出した状態で、センサー部７１がセンサー支持部６４ｂに保持される。この状態では、センサー部７１の凸状先端部が定着ベルト２６の表面に当接し、定着ベルト２６の表面と分離部材５１との間隔は、所定の間隔Ｄより大きい間隔Ｄａにて保持されている。 On the other hand, as shown in FIG. 6, when the sensor unit 71 is deformed downward, the heat-sensitive surface of the sensor unit 71 comes into contact with the lower flange portion of the sensor support unit 64 b, and the heat-sensitive surface of the sensor unit 71 is The sensor portion 71 is held by the sensor support portion 64b in a state in which the convex tip portion protrudes downward from the contact portion 64a of the protruding member 64. In this state, the convex tip of the sensor unit 71 contacts the surface of the fixing belt 26, and the distance between the surface of the fixing belt 26 and the separation member 51 is held at a distance Da that is larger than a predetermined distance D. .

ここで、定着処理を行うために定着ベルト２６の表面が昇温すると、定着ベルト２６や定着ローラー１８（図２参照）が膨張する。定着ベルト２６の表面温度が定着可能温度に到達するまでは、定着ベルト２６や定着ローラー１８が膨張する際に、定着ベルト２６や定着ローラー１８の端部側は外気温の影響を受けやすいために、その中央部が端部に比べて大きく膨張する。そこで、本実施形態では、定着ベルト２６の表面温度が定着可能温度より低いとき、定着ベルト２６の表面と分離部材５１との間隔Ｄａが、定着ベルト２６の端部と中央部との熱膨張量の差より大きくなるように、センサー支持部６４ｂを構成し、突出部材６４の当接部６４ａに対するセンサー部７１の凸状先端部の突出量を設定している。従って、定着処理前において定着ベルト２６の表面が昇温して、定着ベルト２６や定着ローラー１８が膨張しても、分離部材５１が定着ベルト２６の表面に当接することがなく、分離部材５１によって定着ベルト２６の表面が傷つけられることがない。 Here, when the surface of the fixing belt 26 is heated to perform the fixing process, the fixing belt 26 and the fixing roller 18 (see FIG. 2) expand. Until the surface temperature of the fixing belt 26 reaches the fixable temperature, the end side of the fixing belt 26 and the fixing roller 18 is easily affected by the outside air temperature when the fixing belt 26 and the fixing roller 18 expand. The center part expands greatly compared with the end part. Therefore, in this embodiment, when the surface temperature of the fixing belt 26 is lower than the fixable temperature, the distance Da between the surface of the fixing belt 26 and the separation member 51 is the amount of thermal expansion between the end portion and the center portion of the fixing belt 26. The sensor support portion 64b is configured so as to be larger than the difference between the two, and the protruding amount of the convex tip portion of the sensor portion 71 with respect to the contact portion 64a of the protruding member 64 is set. Therefore, even if the surface of the fixing belt 26 is heated before the fixing process and the fixing belt 26 and the fixing roller 18 are expanded, the separating member 51 does not come into contact with the surface of the fixing belt 26 and is separated by the separating member 51. The surface of the fixing belt 26 is not damaged.

（第２実施形態）
図７は第２実施形態に係る定着装置を示す側面図であり、また、図８は第２実施形態に係る定着装置の間隔調整部を示す側面図である。尚、図８は定着処理時及び定着処理直後の分離部材の状態を示す。第１実施形態と異なる、間隔調整部の構成及びその周辺構成について主に説明し、第１実施形態と同じ部分の説明を省略する。 (Second Embodiment)
FIG. 7 is a side view showing a fixing device according to the second embodiment, and FIG. 8 is a side view showing an interval adjusting unit of the fixing device according to the second embodiment. FIG. 8 shows the state of the separating member during the fixing process and immediately after the fixing process. The configuration of the interval adjusting unit and its peripheral configuration, which are different from the first embodiment, will be mainly described, and the description of the same parts as those of the first embodiment will be omitted.

図７に示すように、定着装置５は、電磁誘導加熱方式の熱源を用いた定着方式であり、加熱部材である定着ベルト２６と、加圧部材である加圧ローラー１９と、押圧部材５５と、定着ベルト２６を加熱する誘導加熱部３０と、温度検知部であるサーミスター２５と、定着処理後の用紙９を定着ベルト２６から分離する分離部材５１と、を備える。加圧ローラー１９は定着装置５のハウジング（図略）の長手方向に回転可能に支持され、誘導加熱部３０及び押圧部材５５はハウジングに固定支持され、また、分離部材５１はハウジングに揺動可能に支持される。 As shown in FIG. 7, the fixing device 5 is a fixing method using an electromagnetic induction heating type heat source, and includes a fixing belt 26 that is a heating member, a pressure roller 19 that is a pressure member, and a pressing member 55. And an induction heating unit 30 that heats the fixing belt 26, a thermistor 25 that is a temperature detection unit, and a separation member 51 that separates the sheet 9 after the fixing process from the fixing belt 26. The pressure roller 19 is rotatably supported in the longitudinal direction of the housing (not shown) of the fixing device 5, the induction heating unit 30 and the pressing member 55 are fixedly supported on the housing, and the separation member 51 can swing on the housing. Supported by

押圧部材５５は、押圧パッド５６と円弧ガイド部５９とを有する。押圧パッド５６は定着ベルト２６の内周面に配設され、定着ベルト２６を介して加圧ローラー１９に対向している。また、押圧パッド５６は、定着ベルト２６を加圧ローラー１９側に押圧する。円弧ガイド部５９は、押圧パッド５６の反対側にて誘導加熱部３０に対向して設けられ、誘導加熱部３０に沿って回転するように定着ベルト２６を案内する。 The pressing member 55 includes a pressing pad 56 and an arc guide portion 59. The pressing pad 56 is disposed on the inner peripheral surface of the fixing belt 26, and faces the pressure roller 19 through the fixing belt 26. The pressing pad 56 presses the fixing belt 26 toward the pressure roller 19 side. The arc guide portion 59 is provided on the opposite side of the pressing pad 56 so as to face the induction heating portion 30, and guides the fixing belt 26 so as to rotate along the induction heating portion 30.

誘導加熱部３０は、コイル３７と、ボビン３８と、磁性体コア３９とを備え、電磁誘導により定着ベルト２６を加熱するものである。誘導加熱部３０は、定着ベルト２６の幅方向（図７の紙面の表面から裏面方向）に延びて、定着ベルト２６の外周の略半分を囲うように定着ベルト２６に対向して配設される。 The induction heating unit 30 includes a coil 37, a bobbin 38, and a magnetic core 39, and heats the fixing belt 26 by electromagnetic induction. The induction heating unit 30 extends in the width direction of the fixing belt 26 (from the front surface to the back surface in FIG. 7), and is disposed to face the fixing belt 26 so as to surround substantially half of the outer periphery of the fixing belt 26. .

コイル３７は、定着ベルト２６の幅方向に沿ってループ状に複数回巻回してボビン３８に取り付けられる。またコイル３７は、図示しない電源に接続され、電源から供給される高周波電流により磁界を発生させる。コイル３７の磁界によって磁性体コア３９から発せられる磁束は、図７の紙面に平行な方向に導かれ、定着ベルト２６の誘導発熱層２６ａを貫通する。誘導発熱層２６ａの磁束の周りには渦電流が生じ、渦電流が流れると、誘導発熱層２６ａの電気抵抗によってジュール熱が発生し、その結果、定着ベルト２６が発熱することになる。 The coil 37 is attached to the bobbin 38 by being wound a plurality of times in a loop shape along the width direction of the fixing belt 26. The coil 37 is connected to a power source (not shown) and generates a magnetic field by a high-frequency current supplied from the power source. A magnetic flux generated from the magnetic core 39 by the magnetic field of the coil 37 is guided in a direction parallel to the paper surface of FIG. 7 and penetrates the induction heating layer 26 a of the fixing belt 26. An eddy current is generated around the magnetic flux of the induction heat generation layer 26a. When the eddy current flows, Joule heat is generated by the electric resistance of the induction heat generation layer 26a, and as a result, the fixing belt 26 generates heat.

サーミスター２５は、定着ベルト２６の表面において幅方向の中央部及び両端部に対向するように配置され、夫々の領域の温度を検知する。 The thermistor 25 is disposed on the surface of the fixing belt 26 so as to face the center and both ends in the width direction, and detects the temperature of each region.

分離部材５１は、間隔調整部６０によって定着ベルト２６の表面との間隔を可変にされる。 The distance between the separation member 51 and the surface of the fixing belt 26 is made variable by the distance adjusting unit 60.

図８に示すように、間隔調整部６０は、分離部材５１を揺動可能に支持する支持部材６１と、分離部材５１を定着ベルト２６側に付勢するバネ部材６２と、定着ベルト２６の表面に接離可能である突出部材６４と、分離部材５１を定着ベルト２６の表面から離間する方向に押圧するソレノイド６６と、を有する。ソレノイド６６及びバネ部材６２は作動部を構成する。 As shown in FIG. 8, the interval adjusting unit 60 includes a support member 61 that supports the separation member 51 so as to be swingable, a spring member 62 that urges the separation member 51 toward the fixing belt 26, and a surface of the fixing belt 26. And a solenoid 66 that presses the separation member 51 in a direction away from the surface of the fixing belt 26. The solenoid 66 and the spring member 62 constitute an operating part.

分離部材５１には、そのフランジ部に形成された嵌装孔５１ａと、定着ベルト２６の表面に対向する先端部５１ｂと、嵌装孔５１ａに対して先端部５１ｂの反対側に配置される後端部５１ｃと、が設けられる。嵌装孔５１ａは分離部材５１の長手方向の両端部に形成される。嵌装孔５１ａには、図示しないハウジングに固設された支持部材６１が係合し、分離部材５１は支持部材６１の回りで回動可能となる。バネ部材６２は、引っ張りコイルスプリング等からなり、その一端部がハウジングに固設され、その他端部が分離部材５１に固設される。 The separation member 51 has a fitting hole 51a formed in the flange portion thereof, a tip portion 51b facing the surface of the fixing belt 26, and a rear side disposed on the opposite side of the tip portion 51b with respect to the fitting hole 51a. An end 51c. The fitting holes 51 a are formed at both ends of the separating member 51 in the longitudinal direction. A support member 61 fixed to a housing (not shown) is engaged with the fitting hole 51 a, so that the separation member 51 can rotate around the support member 61. The spring member 62 is formed of a tension coil spring or the like, and one end thereof is fixed to the housing, and the other end is fixed to the separation member 51.

分離部材５１の先端部５１ｂには突出部材６４が設けられる。突出部材６４は、分離部材５１の先端部５１ｂに一体に取り付けられ、バネ部材６２の付勢力によって定着ベルト２６の表面に当接することが可能である。突出部材６４の当接部６４ａが定着ベルト２６の表面に当接することによって、分離部材５１と定着ベルト２６の表面との間隔がＤに設定される。この所定の間隔Ｄだけ定着ベルト２６の表面から離間した状態で、分離部材５１は定着ベルト２６の表面から用紙９を分離する。また、突出部材６４は分離部材５１の両端部に設けられ、最大サイズ用紙の定着処理領域Ａの外側で定着ベルト２６の表面に当接している（図４参照）。 A protruding member 64 is provided at the distal end portion 51 b of the separating member 51. The protruding member 64 is integrally attached to the distal end portion 51 b of the separating member 51, and can come into contact with the surface of the fixing belt 26 by the urging force of the spring member 62. When the contact portion 64 a of the protruding member 64 contacts the surface of the fixing belt 26, the distance between the separation member 51 and the surface of the fixing belt 26 is set to D. The separation member 51 separates the sheet 9 from the surface of the fixing belt 26 while being separated from the surface of the fixing belt 26 by the predetermined distance D. The protruding members 64 are provided at both ends of the separating member 51 and are in contact with the surface of the fixing belt 26 outside the fixing processing area A of the maximum size sheet (see FIG. 4).

ソレノイド６６は、その本体が定着装置５のハウジングに固設され、本体に移動可能に設けたプランジャーが分離部材５１の後端部５１ｃを押圧することが可能である。ソレノイド６６のプランジャーは、分離部材５１の後端部５１ｃから僅かに離間して対向し、ソレノイド６６が通電されると、ソレノイド６６のプランジャーは矢印Ｅ方向に移動する。プランジャーの矢印Ｅ方向への移動にともなって、分離部材５１は、プランジャーによって後端部５１ｃを押され、支持部材６１の回りをバネ部材６２の付勢力に抗して定着ベルト２６の表面から離間する方向に回動するとともに、突出部材６４は定着ベルト２６表面から離間する。 The solenoid 66 has a main body fixed to the housing of the fixing device 5, and a plunger movably provided on the main body can press the rear end 51 c of the separation member 51. The plunger of the solenoid 66 opposes the separation member 51 with a slight distance from the rear end 51c. When the solenoid 66 is energized, the plunger of the solenoid 66 moves in the direction of arrow E. As the plunger moves in the direction of arrow E, the rear end 51c of the separating member 51 is pushed by the plunger, and the surface of the fixing belt 26 against the urging force of the spring member 62 around the support member 61. And the projecting member 64 is separated from the surface of the fixing belt 26.

サーミスター２５（図７参照）が定着ベルト２６の端部の表面温度を検知し、定着ベルト２６の表面温度が例えば１７０℃の定着可能温度である場合、ソレノイド６６は通電することがないように制御される。従って、バネ部材６２によって、突出部材６４の当接部６４ａが定着ベルト２６の表面に当接させられ、定着ベルト２６の表面と分離部材５１との間隔は、所定の間隔Ｄに保持されている。また、定着ベルト２６の表面温度は、定着処理領域Ａ（図４参照）の端部から中央部において略定着可能温度となり、ニップ部Ｎにて用紙９の定着処理が行われる。次に、分離部材５１によって用紙９が定着ベルト２６の表面から分離されるとき、定着処理の直後であるために、定着ベルト２６の表面温度が定着可能温度であり、突出部材６４によって、定着ベルト２６の表面と分離部材５１との間隔が所定の間隔Ｄに保持されており、分離部材５１によって用紙９が定着ベルト２６の表面から良好に分離される。 When the thermistor 25 (see FIG. 7) detects the surface temperature of the end of the fixing belt 26 and the surface temperature of the fixing belt 26 is a fixing possible temperature of, for example, 170 ° C., the solenoid 66 is not energized. Be controlled. Therefore, the contact portion 64 a of the protruding member 64 is brought into contact with the surface of the fixing belt 26 by the spring member 62, and the distance between the surface of the fixing belt 26 and the separation member 51 is maintained at a predetermined distance D. . Further, the surface temperature of the fixing belt 26 becomes substantially fixable temperature from the end portion to the center portion of the fixing processing area A (see FIG. 4), and the fixing processing of the sheet 9 is performed at the nip portion N. Next, when the sheet 9 is separated from the surface of the fixing belt 26 by the separating member 51, immediately after the fixing process, the surface temperature of the fixing belt 26 is the fixing possible temperature, and the fixing member 64 The distance between the surface of 26 and the separating member 51 is maintained at a predetermined distance D, and the sheet 9 is favorably separated from the surface of the fixing belt 26 by the separating member 51.

一方、定着ベルト２６の表面が定着可能温度より低い場合、ソレノイド６６は通電するように制御される。従って、ソレノイド６６のプランジャーが矢印Ｅ方向に移動し、ソレノイド６６によって、分離部材５１は、支持部材６１の回りをバネ部材６２の付勢力に抗して定着ベルト２６の表面から離間する方向に回動し、突出部材６４は定着ベルト２６の表面から離間する。定着ベルト２６の表面と分離部材５１との間隔は、所定の間隔Ｄより大きい間隔Ｄａにて保持されている。 On the other hand, when the surface of the fixing belt 26 is lower than the fixable temperature, the solenoid 66 is controlled to be energized. Accordingly, the plunger of the solenoid 66 moves in the direction of arrow E, and the solenoid 66 causes the separation member 51 to move away from the surface of the fixing belt 26 against the biasing force of the spring member 62 around the support member 61. The protruding member 64 is separated from the surface of the fixing belt 26 by rotating. The distance between the surface of the fixing belt 26 and the separation member 51 is maintained at a distance Da that is larger than a predetermined distance D.

ここで、定着処理を行うために定着ベルト２６の表面が昇温すると、定着ベルト２６が膨張する。定着ベルト２６の表面温度が定着可能温度に到達するまでは、定着ベルト２６が膨張する際に、定着ベルト２６の端部側は外気温の影響を受けやすいために、その中央部が端部に比べて大きく膨張する。そこで、本実施形態では、定着ベルト２６の表面温度が定着可能温度より低いとき、定着ベルト２６の表面と分離部材５１との間隔Ｄａが、定着ベルト２６の端部と中央部との熱膨張量の差より大きくなるように、ソレノイド６６のプランジャーの移動量が設定される。従って、定着処理前において定着ベルト２６の表面が昇温して、定着ベルト２６が膨張しても、分離部材５１が定着ベルト２６の表面に当接することがなく、分離部材５１によって定着ベルト２６の表面が傷つけられることがない。 Here, when the surface of the fixing belt 26 is heated to perform the fixing process, the fixing belt 26 expands. Until the surface temperature of the fixing belt 26 reaches the fixable temperature, when the fixing belt 26 is expanded, the end portion side of the fixing belt 26 is easily affected by the outside air temperature. Compared with the expansion. Therefore, in this embodiment, when the surface temperature of the fixing belt 26 is lower than the fixable temperature, the distance Da between the surface of the fixing belt 26 and the separation member 51 is the amount of thermal expansion between the end portion and the center portion of the fixing belt 26. The movement amount of the plunger of the solenoid 66 is set so as to be larger than the difference. Therefore, even if the surface of the fixing belt 26 is heated before the fixing process and the fixing belt 26 expands, the separating member 51 does not come into contact with the surface of the fixing belt 26, and the separating member 51 causes the fixing belt 26. The surface is not damaged.

尚、作動部をソレノイド６６とバネ部材６２とを有するように構成したが、これに替えて、作動部は、偏心カムを回転させるモーターと、突出部材６４を定着ベルト２６の表面側に付勢するバネ部材とを有する構成とし、モーターの回転駆動によって、偏心カムが回転し、偏心カムの回転によって、偏心カムに当接する分離部材５１が支持部材６１の回りで揺動するようにしてもよい。 Although the operating portion is configured to have the solenoid 66 and the spring member 62, the operating portion urges the motor for rotating the eccentric cam and the protruding member 64 toward the surface of the fixing belt 26 instead. The eccentric cam may be rotated by the rotational drive of the motor, and the separation member 51 that contacts the eccentric cam may swing around the support member 61 by the rotation of the eccentric cam. .

また、上記実施形態では、加熱部材として無端状の定着ベルトを使用するベルト方式の定着装置に適用した例を示したが、本発明はこれに限らず、加熱部材として加熱ローラーを使用するローラー方式の定着装置に適用してもよい。また、熱源にヒーターを用いてもよい。 In the above-described embodiment, an example in which the present invention is applied to a belt-type fixing device that uses an endless fixing belt as a heating member has been shown. However, the present invention is not limited thereto, and a roller method that uses a heating roller as a heating member. The present invention may also be applied to other fixing devices. A heater may be used as the heat source.

本発明は、複写機、プリンター、ファクシミリ、それらの複合機等の画像形成装置に用いる定着装置及びそれを備えた画像形成装置に利用することができる。 The present invention can be used for a fixing device used in an image forming apparatus such as a copying machine, a printer, a facsimile machine, and a composite machine thereof, and an image forming apparatus including the same.

１画像形成装置
５定着装置
１８定着ローラー
１９加圧ローラー(加圧部材）
２５サーミスター（温度検知部）
２６定着ベルト（加熱部材）
３０誘導加熱部
５１分離部材
５１ａ嵌装孔
５１ｂ先端部
５１ｃ後端部
５５押圧部材
６０間隔調整部
６１支持部材
６２バネ部材（作動部）
６４突出部材
６４ａ当接部
６４ｂセンサー支持部
６４ｃ基部
６６ソレノイド（作動部）
７１センサー部（温度検知部）
Ａ最大サイズ用紙の定着処理領域
Ｄ所定の間隔 DESCRIPTION OF SYMBOLS 1 Image forming apparatus 5 Fixing apparatus 18 Fixing roller 19 Pressure roller (Pressure member)
25 Thermistor (Temperature detector)
26 Fixing belt (heating member)
30 Induction heating part 51 Separating member 51a Fitting hole 51b Front end part 51c Rear end part 55 Pressing member 60 Space adjusting part 61 Support member 62 Spring member (actuating part)
64 Projection member 64a Contact part 64b Sensor support part 64c Base part 66 Solenoid (actuation part)
71 Sensor unit (temperature detection unit)
A Maximum size paper fixing process area D Predetermined interval

Claims

In a fixing device that sandwiches a recording medium carrying an unfixed toner image at a nip formed by a heating member and a pressure member pressed against the heating member, and melts and fixes the unfixed toner image on the recording medium ,
A separation member that separates the recording medium after the fixing process from the surface of the heating member in a state of being separated from the surface of the heating member by a predetermined interval;
A support member for swingably supporting the separation member;
Protruding members disposed to project from the both ends in the longitudinal direction of the separating member to the surface side of the heating member;
A sensor unit supported in a deformable manner at the tip of the projecting member;
With
The sensor section is deformed in a first direction away from the surface of the heating member when the detected temperature is a fixable temperature, and is adjacent to the surface of the heating member when the detected temperature is lower than the fixable temperature. Deformed in the direction of 2,
When the sensor part is deformed in the first direction, the protruding member abuts on the surface of the heating member, and the separation member is moved so that the distance between the surface of the heating member and the separation member becomes a predetermined distance. ,
When the sensor part is deformed in the second direction, the sensor part comes into contact with the surface of the heating member, and the distance between the surface of the heating member and the separation member is the heat between the end part and the central part of the heating member. A fixing device, wherein the separating member is moved to be larger than a difference in expansion amount.

An image forming apparatus comprising the fixing device according to claim 1 .