JP2011191453A - Fixing device and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce a curling amount through a continuous paper passage from the start of a paper passage just after warming up and to secure fixability. <P>SOLUTION: A fixing device nipping a transfer paper by a pair of fixing members 51 and pressure member 52 facing each other, to fix a toner image on the transfer paper by applying heat and pressure includes: a fixing member heater 53 for heating the fixing member 51; a temperature detecting member 57 detecting a temperature of the fixing member 51; a pressure member heater 54 for heating the pressure member 52; temperature detecting members 55 and 56 detecting a temperature of the pressure member 52, the temperature detecting members 55 and 56 being arranged at the upstream and downstream of a nip respectively; and a temperature controller 100 for controlling a temperature of the pressure member 52 based on the temperature detecting members 55, 56 and 57. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

本発明は定着装値及び画像形成装置に係り、特に互いに対向する一対の定着部材及び加圧部材により転写紙を挟み込み、熱および圧力を加えてトナー像を前記転写紙上に定着させる定着装置及びこの定着装置を備える画像形成装置に関する。   The present invention relates to a fixing device and an image forming apparatus, and in particular, a fixing device that sandwiches a transfer sheet by a pair of fixing members and a pressure member facing each other and applies heat and pressure to fix the toner image on the transfer sheet, and the fixing apparatus. The present invention relates to an image forming apparatus including a fixing device.

電子複写機等の画像形成装置の定着装置は、ヒートロール定着方式、ベルト定着方式、ＩＨ定着方式等のものがあり、これらは、転写紙の画像面側からトナー像を加熱しこれと圧接する加圧ローラとの間に画像転写済みの転写紙を通過させることによりトナー像を熱定着する。   The fixing device of an image forming apparatus such as an electronic copying machine includes a heat roll fixing method, a belt fixing method, an IH fixing method, etc., and these heat the toner image from the image surface side of the transfer paper and press the toner image. The toner image is heat-fixed by passing the transfer paper on which the image has been transferred between the pressure roller.

トナー像の熱定着には最適の温度があるため、最適温度を含む所定の温度範囲を維持するよう熱源の通電・非通電は自動制御されている。このような自動制御は、感温素子としてのサーミスタを加熱部材に摺接させたり、サーモパイル等を非接触で赤外線検知したりする等して加熱部材の温度を検知して、その出力を温度制御部へ送り熱源への電力供給を調整することにより実現している。   Since there is an optimum temperature for thermal fixing of the toner image, energization / non-energization of the heat source is automatically controlled so as to maintain a predetermined temperature range including the optimum temperature. Such automatic control detects the temperature of the heating member by causing the thermistor as a temperature sensing element to slide in contact with the heating member, or detecting the thermopile or the like without contact with infrared rays, and controls the temperature of the output. This is achieved by adjusting the power supply to the heat source.

特許文献１には、加圧ローラ内にヒータを設けた熱ローラ定着装置で、カールが生じないか又は生じても僅かなカール量であるようにするため、加圧ローラを内部にヒータを設けその外側に金属の芯金を配置し、周面は高熱伝導率の弾性体によって被覆して構成し、芯金の太径部分で、弾性体によって被覆されていない端部近くの芯金に直接接触する温度センサを配置し、この温度センサによってヒータの点滅制御を行うものが記載されている。   In Patent Document 1, a heat roller fixing device in which a heater is provided in a pressure roller is provided with a heater in the pressure roller in order to prevent curling from occurring or a slight curl amount even if it occurs. A metal cored bar is placed on the outside, and the peripheral surface is covered with an elastic body having high thermal conductivity, and the large diameter part of the cored bar is directly on the cored bar near the end not covered by the elastic body. There is a description that a temperature sensor that is in contact is arranged and the heater blinking control is performed by this temperature sensor.

また、特許文献２には、用紙のカール量を抑制して用紙トレイ上での用紙積載性悪化を改善するため、画像形成装置は、ヒータにより加熱される定着ベルトと、ヒータにより加熱され定着ベルトに圧接されて定着ベルトとの間に定着ニップを形成する加圧ローラとを有する定着装置と、ヒータをそれぞれオンオフ制御することにより定着ベルトおよび加圧ローラをそれぞれ温度調節できる制御部とを備え、制御部は、環境温度が所定値を上回ると加圧ローラの温度を通常より高く設定するものが記載されている。   Japanese Patent Application Laid-Open No. 2004-228688 discloses that an image forming apparatus includes a fixing belt heated by a heater and a fixing belt heated by the heater in order to suppress the curling amount of the sheet and improve deterioration of the paper stackability on the paper tray. A fixing device having a pressure roller that is in pressure contact with the fixing belt to form a fixing nip, and a controller that can adjust the temperature of the fixing belt and the pressure roller by controlling the heaters on and off, respectively. The control section describes that the temperature of the pressure roller is set higher than usual when the environmental temperature exceeds a predetermined value.

しかし、このように加熱部材の温度を所定の範囲内に制御しても、外気温度や外気湿度の状態によって定着性能は左右される。即ち外気温度が低い場合には、転写紙の温度が低くなり、外気湿度が高い場合には転写紙が吸湿して含水率が高くなり、定着性能が悪化する傾向にある。これは加熱面の温度が同じであってもニップ部での紙の温度上昇の程度が異なってくるからである。   However, even if the temperature of the heating member is controlled within a predetermined range as described above, the fixing performance depends on the state of the outside air temperature and the outside air humidity. That is, when the outside air temperature is low, the temperature of the transfer paper is low, and when the outside air humidity is high, the transfer paper absorbs moisture and the moisture content becomes high, and the fixing performance tends to deteriorate. This is because even if the temperature of the heating surface is the same, the degree of the temperature rise of the paper at the nip portion is different.

このような定着性能の悪化を防止するため、従来の画像形成装置では、外気温度及び外気湿度を検出する手段を備えその出力に応じて加熱面の温度を制御する定着装置や、あるいは紙の含水率を検出して加熱部材の温度を制御する画像形成装置等が提案されてきた。   In order to prevent such deterioration of the fixing performance, the conventional image forming apparatus is provided with a means for detecting the outside air temperature and the outside air humidity, and controls the temperature of the heating surface according to the output, or the water content of the paper An image forming apparatus that detects the rate and controls the temperature of the heating member has been proposed.

これらの方法は定着性を高めるのには有効な手段であるが、一般的には紙の含水率が高くなると温度の低い加圧ローラ側に紙がカールすることが知られており、この傾向は加熱部材と加圧部材の温度差が大きくなるとより顕著になる。このようなカール量の増大は通紙性能を低下させジャムの原因にもなる。   These methods are effective means for improving the fixing property, but it is generally known that when the moisture content of the paper is high, the paper curls on the pressure roller side having a low temperature. Becomes more prominent when the temperature difference between the heating member and the pressure member increases. Such an increase in the curl amount deteriorates the paper passing performance and causes a jam.

一方、定着後のカールを低減させる手段としては、例えば加熱部材及び加圧部材の双方に熱源を備え、加圧部材の熱源に通電して加圧部材温度を一定値以上にする画像形成装置が提案されている。   On the other hand, as a means for reducing curling after fixing, for example, there is an image forming apparatus in which both the heating member and the pressure member are provided with heat sources, and the heat source of the pressure member is energized to set the pressure member temperature to a certain value or more. Proposed.

ところが加圧部材はシリコンゴム等の弾性部材で備えた層を備えており、一般的にニップ幅を確保する目的からこのシリコンゴムの層の厚みを確保する必要があるため、熱容量が大きくなる。他方、装置が使用可能な電力の制限から加圧部材に与える熱源の電力容量は小さくせざるを得ない。その結果、定着部材に比べて加圧部材を十分に温めるのには時間を要することとなる。特に定着装置が冷えた状態である、電源ＯＮ直後、省エネモードからの復帰直後にはこの傾向が顕著である。   However, the pressure member has a layer provided by an elastic member such as silicon rubber, and since it is generally necessary to secure the thickness of the silicon rubber layer for the purpose of securing the nip width, the heat capacity increases. On the other hand, the power capacity of the heat source given to the pressure member is inevitably reduced due to the limitation of the power that can be used by the apparatus. As a result, it takes time to sufficiently warm the pressure member as compared to the fixing member. This tendency is particularly noticeable immediately after the power is turned on and immediately after the return from the energy saving mode, where the fixing device is in a cold state.

また加圧部材の設定温度は、その補助的な機能のため、定着部材温度より低い設定とされることが一般的である。このため通紙のために装置が回転を始めると高い温度の定着部材表面から熱を貰い加圧部材表面の温度は上昇する。その結果、加熱部材の加熱源は非通電となるが実際は熱容量の大半を占める内部の加熱は不十分のままであり、転写紙がニップ部を通過するとその表面の熱が奪われ、また内部熱源からの供給が間に合わず温度が低下する。しかも上述のように十分な電力が供給されないため、一度落ち込んだ温度が設定温度に戻るためには時間がかかり、結果として用紙のカールが大きくなり、定着不良となる。加圧部材に十分に蓄熱されていないと、この不具合現象が顕著となる。   The set temperature of the pressure member is generally set lower than the fixing member temperature because of its auxiliary function. For this reason, when the apparatus starts rotating for paper passing, heat is applied from the surface of the fixing member having a high temperature, and the temperature of the pressure member surface rises. As a result, the heating source of the heating member is de-energized, but the internal heating that occupies most of the heat capacity is still insufficient, and when the transfer paper passes through the nip, the heat of the surface is taken away, and the internal heat source The supply will not be in time and the temperature will drop. In addition, since sufficient electric power is not supplied as described above, it takes time for the temperature once lowered to return to the set temperature, resulting in increased paper curl and poor fixing. If the heat is not sufficiently stored in the pressurizing member, this malfunction phenomenon becomes significant.

そこで本発明は、ウォームアップ直後の通紙においても加圧部材の温度が落ち込むことを防止し加熱部材及び加圧部材間の温度差を所定の範囲に維持でき、ウォームアップ直後の通紙開始から連続通紙を通じてカール量の低減、定着性の確保を図ることができる定着装値及び画像形成装置を提供することを目的とする。   Therefore, the present invention can prevent the temperature of the pressure member from dropping even during paper feeding immediately after warm-up, and can maintain the temperature difference between the heating member and the pressure member within a predetermined range. It is an object of the present invention to provide a fixing device value and an image forming apparatus capable of reducing a curl amount and ensuring fixing properties through continuous paper feeding.

請求項１の発明は、互いに対向する一対の定着部材及び加圧部材により転写紙を挟み込み、熱および圧力を加えてトナー像を前記転写紙上に定着させる定着装置において、前記定着部材を加熱する定着部材加熱手段と、定着部材の温度を検出する少なくとも１つの定着部材温度検知手段と、前記加圧部材を加熱する加圧部材加熱手段と、前記加圧部材の温度を検出する少なくとも２つの加圧部材温度検知手段と、前記加圧部材温度検知手段は定着部材と加圧部材から形成されるニップ部の上流と下流とにそれぞれ配置されており、前記加圧部材の温度制御を前記定着部温度検知手段及び加圧部温度検知手段に基づいて行う温度制御手段を備えることを特徴とする定着装置である。   According to a first aspect of the present invention, there is provided a fixing device in which a transfer paper is sandwiched between a pair of fixing members and a pressure member facing each other, and a toner image is fixed on the transfer paper by applying heat and pressure. A member heating means; at least one fixing member temperature detecting means for detecting the temperature of the fixing member; a pressure member heating means for heating the pressure member; and at least two pressures for detecting the temperature of the pressure member. The member temperature detecting means and the pressure member temperature detecting means are respectively arranged upstream and downstream of the nip formed by the fixing member and the pressure member, and the temperature control of the pressure member is controlled by the fixing portion temperature. The fixing device includes a temperature control unit that performs based on the detection unit and the pressure unit temperature detection unit.

請求項２の発明は、請求項１記載の定着装置において、前記温度制御手段は、前記加圧部材温度検知手段における上流側の検知温度Ｔｂ、下流側の検知温度Ｔｃ、ウォームアップに要する時間ｔとし、Ｔｃ−Ｔｂをウォームアップ中の期間中積分した値に機器固有の定数ｋ１を乗じた値Σ〔（Ｔｃ−Ｔｂ）・ｔ〕・ｋ１に基づいてウォームアップ直後における加圧部材待機時設定温度を通常における加圧部材待機時設定温度よりも高く設定することを特徴とする。   According to a second aspect of the present invention, in the fixing device according to the first aspect, the temperature control means includes an upstream detection temperature Tb, a downstream detection temperature Tc, and a time t required for warm-up in the pressure member temperature detection means. And setting of the pressure member waiting time immediately after the warm-up based on a value Σ [(Tc-Tb) · t] · k1 obtained by multiplying the value obtained by integrating Tc−Tb during the warm-up period and a constant k1 inherent to the device. It is characterized in that the temperature is set higher than the normal set temperature during standby of the pressure member.

請求項３の発明は、請求項１記載の定着装置において、前記温度制御手段は、前記加圧部材の温度検知手段における上流側の検知温度Ｔｂ、下流側の検知温度Ｔｃ、定着部材の検知温度Ｔａ、ウォームアップに要する時間をｔとし、Ｔａ−（Ｔｃ＋Ｔｂ）／２をウォームアップ中の期間中積分した値に機器固有の定数ｋ２を乗じた値Σ〔Ｔａ−（Ｔｃ＋Ｔｂ）／２・ｔ〕・ｋ２に応じてウォームアップ直後の加圧部材待機時設定温度を通常の加圧部材待機時設定温度よりも高く設定することを特徴とする。   According to a third aspect of the present invention, in the fixing device according to the first aspect, the temperature control means includes an upstream detection temperature Tb, a downstream detection temperature Tc, and a fixing member detection temperature in the temperature detection means of the pressure member. Ta, t is the time required for warm-up, and Σ [Ta- (Tc + Tb) / 2 · t] obtained by multiplying Ta- (Tc + Tb) / 2 integrated during the warm-up period by a device-specific constant k2 The pressure member standby set temperature immediately after warm-up is set higher than the normal pressure member standby set temperature according to k2.

請求項４の発明は、請求項１から請求項３までの何れか一項に記載の定着装置において、前記温度制御手段は、ウォームアップ中の定着部材の第一の目標温度、第二の目標温度を設定し、ウォームアップ中に第一の目標温度に到達した時点で加圧部材温度が加圧部材待機時設定温度に加算分を加えた温度に到達していない場合に定着部材を第二の目標温度まで加熱継続することを特徴とする。   According to a fourth aspect of the present invention, in the fixing device according to any one of the first to third aspects, the temperature control means includes a first target temperature and a second target temperature of the fixing member being warmed up. When the temperature is set and the first target temperature is reached during warm-up, if the pressure member temperature does not reach the temperature obtained by adding the additional pressure to the pressure member standby set temperature, The heating is continued until the target temperature is maintained.

請求項５の発明は、請求項１から請求項４までの何れか一項に記載の定着装置において、前記温度制御手段は、ウォームアップ中の定着部材の第一の目標温度、第二の目標温度を設定し、ウォームアップ中に第一の目標温度に到達した時点で加圧部材温度が加圧部材待機時設定温度に加算分を加えた温度に到達していない場合、定着部材を第二の目標温度まで加熱継続し、加圧部材が加圧部材待機時設定温度に加算分を加えた温度に到達した後に加算分を段階的に戻すことを特徴とする。   According to a fifth aspect of the present invention, in the fixing device according to any one of the first to fourth aspects, the temperature control means includes a first target temperature and a second target temperature of the fixing member being warmed up. When the temperature is set and the pressure member temperature does not reach the temperature obtained by adding the pressure member standby set temperature when the first target temperature is reached during warm-up, the fixing member is The heating is continued to the target temperature, and after the pressure member reaches the temperature obtained by adding the additional amount to the pressure member standby temperature setting, the additional amount is returned stepwise.

請求項６の発明は、請求項１から請求項５までの何れか一項に記載の定着装置を備えることを特徴とする画像形成装置である。   A sixth aspect of the present invention is an image forming apparatus comprising the fixing device according to any one of the first to fifth aspects.

本発明によれば、加圧部材の温度制御を前記定着部温度検知手段及び加圧部温度検知手段に基づいて行う温度制御手段で行うので、ウォームアップ直後の通紙においても加圧部材の温度が落ち込むことを防止し加熱部材及び加圧部材間の温度差を所定の範囲に維持でき、ウォームアップ直後の通紙開始から連続通紙を通じてカール量の低減、定着性の確保を図ることができる。   According to the present invention, the temperature of the pressure member is controlled by the temperature control means that performs the temperature control based on the fixing part temperature detection means and the pressure part temperature detection means. The temperature difference between the heating member and the pressure member can be maintained within a predetermined range, and the curl amount can be reduced and the fixing property can be ensured through the continuous paper feeding immediately after the warming up. .

実施例に係る画像形成装置の概略構成を示す断面図である。1 is a cross-sectional view illustrating a schematic configuration of an image forming apparatus according to an embodiment. 定着装置の構成を示す模式図である。FIG. 2 is a schematic diagram illustrating a configuration of a fixing device. 加熱部材の構成を示す模式図である。It is a schematic diagram which shows the structure of a heating member. ウォームアップ時における定着部材と加圧部材の温度を示すグラフである。It is a graph which shows the temperature of the fixing member and pressurizing member at the time of warm-up. 加圧部材の内周面から外周面までの温度分布を示すグラフであるIt is a graph which shows temperature distribution from the inner peripheral surface of a pressurization member to an outer peripheral surface. 加圧部材のゴム層の断面図である。It is sectional drawing of the rubber layer of a pressurization member. ウォームアップ時の定着部材と加圧部材の表面温度の推移を示すグラフである。It is a graph which shows transition of the surface temperature of the fixing member and pressurizing member at the time of warm-up. 加圧部材の内周面から外周面までの温度分布を示すグラフである。It is a graph which shows temperature distribution from the inner peripheral surface of a pressurization member to an outer peripheral surface. 加圧部材の内周面から外周面までの温度分布を示すグラフである。It is a graph which shows temperature distribution from the inner peripheral surface of a pressurization member to an outer peripheral surface.

本発明に係る定着装値は、互いに対向する一対の定着部材及び加圧部材により転写紙を挟み込み、熱および圧力を加えてトナー像を前記転写紙上に定着させる定着装置において、前記定着部材を加熱する定着部材加熱手段と、定着部材の温度を検出する少なくとも１つの定着部材温度検知手段と、前記加圧部材を加熱する加圧部材加熱手段と、前記加圧部材の温度を検出する少なくとも２つの加圧部材温度検知手段と、前記加圧部材温度検知手段は定着部材と加圧部材から形成されるニップ部の上流と下流とにそれぞれ配置されており、前記加圧部材の温度制御を前記定着部温度検知手段及び加圧部温度検知手段に基づいて行う温度制御手段を備えるものである。   The fixing device according to the present invention includes a fixing device in which a transfer paper is sandwiched between a pair of fixing members and a pressure member facing each other, and heat and pressure are applied to fix the toner image on the transfer paper. A fixing member heating means for detecting, at least one fixing member temperature detecting means for detecting the temperature of the fixing member, a pressure member heating means for heating the pressure member, and at least two for detecting the temperature of the pressure member. The pressure member temperature detecting means and the pressure member temperature detecting means are respectively arranged upstream and downstream of a nip formed by the fixing member and the pressure member, and the temperature control of the pressure member is controlled by the fixing. The temperature control means is provided based on the part temperature detection means and the pressure part temperature detection means.

また、本発明に係る定着装置において、前記温度制御手段は、前記加圧部材温度検知手段における上流側の検知温度Ｔｂ、下流側の検知温度Ｔｃ、ウォームアップに要する時間ｔとし、Ｔｃ−Ｔｂをウォームアップ中の期間中積分した値に機器固有の定数ｋ１を乗じた値Σ〔（Ｔｃ−Ｔｂ）・ｔ〕・ｋ１に基づいてウォームアップ直後における加圧部材待機時設定温度を通常における加圧部材待機時設定温度よりも高く設定することができる。   Further, in the fixing device according to the present invention, the temperature control means sets the upstream detection temperature Tb, the downstream detection temperature Tc, and the time t required for warm-up in the pressure member temperature detection means, and Tc−Tb is set as Tc−Tb. Based on a value Σ [(Tc−Tb) · t] · k1 obtained by multiplying the value integrated during the warm-up period by a constant k1 inherent to the device, the set pressure during standby of the pressurizing member immediately after the warm-up is normally applied. The temperature can be set higher than the set temperature during standby of the member.

また、発明に係る定着装値において、前記温度制御手段は、前記加圧部材の温度検知手段における上流側の検知温度Ｔｂ、下流側の検知温度Ｔｃ、定着部材の検知温度Ｔａ、ウォームアップに要する時間をｔとし、Ｔａ−（Ｔｃ＋Ｔｂ）／２をウォームアップ中の期間中積分した値に機器固有の定数ｋ２を乗じた値Σ〔Ｔａ−（Ｔｃ＋Ｔｂ）／２・ｔ〕・ｋ２に応じてウォームアップ直後の加圧部材待機時設定温度を通常の加圧部材待機時設定温度よりも高く設定することができる。   In the fixing apparatus according to the invention, the temperature control means is required for the upstream detection temperature Tb, the downstream detection temperature Tc, the fixing member detection temperature Ta, and the warm-up in the temperature detection means of the pressure member. Warm in accordance with a value Σ [Ta− (Tc + Tb) / 2 · t] · k2 obtained by multiplying the value obtained by integrating Ta− (Tc + Tb) / 2 during the warm-up period with a constant k2 inherent to the device, where time is t It is possible to set the pressure member standby set temperature immediately after the increase to be higher than the normal pressure member standby set temperature.

また、本発明に係る定着装置において、前記温度制御手段は、ウォームアップ中の定着部材の第一の目標温度、第二の目標温度を設定し、ウォームアップ中に第一の目標温度に到達した時点で加圧部材温度が加圧部材待機時設定温度に加算分を加えた温度に到達していない場合に定着部材を第二の目標温度まで加熱継続することができる。   In the fixing device according to the present invention, the temperature control means sets the first target temperature and the second target temperature of the fixing member during warm-up, and reaches the first target temperature during warm-up. When the pressure member temperature does not reach the temperature obtained by adding the added amount to the pressure member standby set temperature at the time, the fixing member can be continuously heated to the second target temperature.

さらに、本発明に係る定着装置において、前記温度制御手段は、ウォームアップ中の定着部材の第一の目標温度、第二の目標温度を設定し、ウォームアップ中に第一の目標温度に到達した時点で加圧部材温度が加圧部材待機時設定温度に加算分を加えた温度に到達していない場合、定着部材を第二の目標温度まで加熱継続し、加圧部材が加圧部材待機時設定温度に加算分を加えた温度に到達した後に加算分を段階的に戻すことができる。   Further, in the fixing device according to the present invention, the temperature control unit sets a first target temperature and a second target temperature of the fixing member during warm-up, and reaches the first target temperature during warm-up. If the pressure member temperature does not reach the temperature obtained by adding the additional pressure to the pressure member standby setting temperature at that time, the fixing member is continuously heated to the second target temperature, and the pressure member is in the pressure member standby state. After reaching the temperature obtained by adding the addition to the set temperature, the addition can be returned in stages.

そして、本発明に係る画像形成装置は、前記定着装置を備えるものである。   An image forming apparatus according to the present invention includes the fixing device.

以下実施例に係る画像形成装置について説明する。以下、本発明を、画像形成装置であるカラーレーザプリンタ（以下、単に「プリンタ」という）に適用した実施形態について説明する。図１は実施例に係る画像形成装置の概略構成を示す断面図である。このプリンタは、イエロー・シアン・マゼンタ・ブラックの４つの画像形成手段を横に並べて配置してタンデム画像形成部を構成する。タンデム画像形成部においては、個々のトナー像形成手段である画像形成手段１０１Ｙ，１０１Ｃ，１０１Ｍ，１０１Ｋが、図中有左から順に配置されている。ここで、各符号の添字Ｙ、Ｃ、Ｍ、Ｋは、それぞれイエロー、マゼンダ、シアン、黒用の部材であることを示す。また、タンデム画像形成部においては、個々の画像形成手段１０１Ｙ，１０１Ｃ，１０１Ｍ，１０１Ｋは、潜像担持体としてのドラム状の感光体２１Ｙ，２１Ｃ，２１Ｍ，２１Ｋのまわりに、帯電装置、現像装置１０Ｙ，１０Ｃ，１０Ｍ，１０Ｋ、感光体クリーニング装置等を備えている。プリンタの上部には、イエロー、シアン、マゼンタ、黒の各色トナーが充填されたトナーボトル２Ｙ，２Ｃ，２Ｍ，２Ｋが配置されている。そして、このトナーボトル２Ｙ，２Ｃ，２Ｍ，２Ｋから図示しない搬送経路によって、所定の補給量だけ各色の現像装置１０Ｙ，１０Ｃ，１０Ｍ，１０Ｋ、に各色トナーが補給される。   The image forming apparatus according to the embodiment will be described below. Hereinafter, an embodiment in which the present invention is applied to a color laser printer (hereinafter simply referred to as “printer”) as an image forming apparatus will be described. FIG. 1 is a cross-sectional view illustrating a schematic configuration of an image forming apparatus according to an embodiment. In this printer, four image forming units of yellow, cyan, magenta, and black are arranged side by side to constitute a tandem image forming unit. In the tandem image forming unit, image forming units 101Y, 101C, 101M, and 101K, which are individual toner image forming units, are arranged in order from the left in the figure. Here, the suffixes Y, C, M, and K of the respective symbols indicate members for yellow, magenta, cyan, and black, respectively. In the tandem image forming unit, each of the image forming units 101Y, 101C, 101M, and 101K includes a charging device and a developing device around the drum-shaped photoconductors 21Y, 21C, 21M, and 21K as latent image carriers. 10Y, 10C, 10M, 10K, a photoconductor cleaning device, and the like. At the top of the printer, toner bottles 2Y, 2C, 2M, and 2K filled with yellow, cyan, magenta, and black color toners are arranged. Each color toner is replenished from the toner bottles 2Y, 2C, 2M, and 2K to the developing devices 10Y, 10C, 10M, and 10K of the respective colors by a predetermined replenishment amount through a conveyance path (not shown).

また、タンデム画像形成部の下部に潜像形成手段としての光書込ユニット９を設ける。この光書込ユニット９は、光源、ポリゴンミラー、ｆ−θレンズ、反射ミラー等を備え、画像データに基づいて各感光体２１Ｙ，２１Ｃ，２１Ｍ，２１Ｋの表面にレーザ光を走査しながら照射するように構成されている。   Further, an optical writing unit 9 as a latent image forming unit is provided below the tandem image forming unit. The optical writing unit 9 includes a light source, a polygon mirror, an f-θ lens, a reflection mirror, and the like, and irradiates the surface of each of the photoreceptors 21Y, 21C, 21M, and 21K while scanning the laser beam based on image data. It is configured as follows.

更に、タンデム画像形成部の直上には、中間転写体として無端ベルト状の中間転写ベルト１を設けている。この中間転写ベルト１は、支持ローラ１ａ、１ｂに掛け回され、この支持ローラのうち駆動ローラとなる支持ローラ１ａの回転軸には駆動源としての図示しない駆動モータが連結されている。この駆動モータを駆動させると、中間転写ベルト１が図中反時計回りに回転移動するとともに、従動可能な支持ローラ１ｂが回転する。中間転写ベルト１０の内側には、感光体２１Ｙ，２１Ｃ，２１Ｍ，２１Ｋ上に形成されたトナー像を中間転写ベルト１上に転写するための一次転写装置１１Ｙ，１１Ｃ，１１Ｍ，１１Ｋを設ける。   Further, an endless belt-like intermediate transfer belt 1 is provided as an intermediate transfer member immediately above the tandem image forming unit. The intermediate transfer belt 1 is wound around support rollers 1a and 1b, and a drive motor (not shown) serving as a drive source is connected to a rotation shaft of the support roller 1a serving as a drive roller among the support rollers. When this drive motor is driven, the intermediate transfer belt 1 rotates counterclockwise in the figure and the followable support roller 1b rotates. Inside the intermediate transfer belt 10, primary transfer devices 11Y, 11C, 11M, and 11K for transferring the toner images formed on the photoreceptors 21Y, 21C, 21M, and 21K onto the intermediate transfer belt 1 are provided.

また、上記一次転写装置１１Ｙ，１１Ｃ，１１Ｍ，１１Ｋより中間転写ベルト１の駆動方向下流に二次転写装置としての二次転写ローラ４を設ける。この二次転写ローラ４と中間転写ベルト１を挟んで反対の側には、支持ローラ１ｂが配置されており、押部材としての機能を果たしている。また、給紙カセット８、給紙コロ７、レジストローラ６等を備えている。さらに、二次転写ローラ４によりトナー像を転写された記録媒体Ｓの進行方向に関して二次転写ローラ４の下流部には、記録媒体Ｓ上の画像を定着する定着装置５、排紙ローラ３を備えている。前記定着装置５は本実施例に係る構成を備える。   Further, a secondary transfer roller 4 as a secondary transfer device is provided downstream of the primary transfer devices 11Y, 11C, 11M, and 11K in the driving direction of the intermediate transfer belt 1. A support roller 1b is disposed on the opposite side of the secondary transfer roller 4 and the intermediate transfer belt 1, and functions as a pressing member. Further, a paper feed cassette 8, a paper feed roller 7, a registration roller 6 and the like are provided. Further, a fixing device 5 for fixing an image on the recording medium S and a paper discharge roller 3 are provided downstream of the secondary transfer roller 4 with respect to the traveling direction of the recording medium S to which the toner image is transferred by the secondary transfer roller 4. I have. The fixing device 5 has a configuration according to this embodiment.

次に、上記プリンタの動作を説明する。個々の画像形成手段でその感光体２１Ｙ，２１Ｃ，２１Ｍ，２１Ｋを回転し、感光体２１Ｙ，２１Ｃ，２１Ｍ，２１Ｋの回転とともに、まず帯電装置１７Ｙ，１７Ｃ，１７Ｍ，１７Ｋで感光体２１Ｙ，２１Ｃ，２１Ｍ，２１Ｋの表面を一様に帯電する。次いで画像データを光書込ユニット９からのレーザによる書込み光を照射して感光体２１Ｙ，２１Ｃ，２１Ｍ，２１Ｋ上に静電潜像を形成する。その後、現像装置１０Ｙ，１０Ｃ，１０Ｍ，１０Ｋによりトナーが付着され静電潜像を可視像化することで各感光体２１Ｙ，２１Ｃ，２１Ｍ，２１Ｋ上にそれぞれ、イエロー・シアン・マゼンタ・ブラックの単色画像を形成する。また、不図示の駆動モータで駆動ローラとなる支持ローラ１ａを回転駆動して従動ローラである支持ローラ１ｂ、二次転写ローラ４を従動回転し、中間転写ベルト１を回転搬送して、その可視像を一次転写装置１１Ｙ，１１Ｃ，１１Ｍ，１１Ｋで中間転写ベルト１上に順次転写する。これによって中間転写ベルト１上に合成カラー画像を形成する。画像転写後の感光体２１Ｙ，２１Ｃ，２１Ｍ，２１Ｋの表面は感光体クリーニング装置で残留トナーを除去して清掃して再度の画像形成に備える。   Next, the operation of the printer will be described. The photoreceptors 21Y, 21C, 21M, and 21K are rotated by the individual image forming units, and the photoreceptors 21Y, 21C, and 21C are first rotated by the charging devices 17Y, 17C, 17M, and 17K as the photoreceptors 21Y, 21C, 21M, and 21K rotate. The surfaces of 21M and 21K are uniformly charged. Next, the image data is irradiated with writing light by a laser from the optical writing unit 9 to form electrostatic latent images on the photoreceptors 21Y, 21C, 21M, and 21K. Thereafter, toner is attached by the developing devices 10Y, 10C, 10M, and 10K, and the electrostatic latent images are visualized to form yellow, cyan, magenta, and black on the photoreceptors 21Y, 21C, 21M, and 21K, respectively. A monochromatic image is formed. In addition, a support roller 1a serving as a drive roller is driven to rotate by a drive motor (not shown), the support roller 1b serving as a driven roller and the secondary transfer roller 4 are driven to rotate, and the intermediate transfer belt 1 is rotated and conveyed to enable its transfer. The visual images are sequentially transferred onto the intermediate transfer belt 1 by the primary transfer devices 11Y, 11C, 11M, and 11K. As a result, a composite color image is formed on the intermediate transfer belt 1. The surface of the photoconductors 21Y, 21C, 21M, and 21K after image transfer is cleaned by removing residual toner with a photoconductor cleaning device to prepare for image formation again.

また、上記画像形成のタイミングにあわせて、給紙カセット８からは記録媒体Ｓ先端が給紙コロ７により繰り出され、レジストローラ６まで搬送され、一旦停止する。そして、上記画像形成動作とタイミングを取りながら、二次転写ローラ４と中間転写ベルト１の間に搬送される。ここで、中間転写ベルト１と二次転写対向ローラである支持ローラ１ｂとは記録媒体Ｓを挟んでいわゆる二次転写ニップを形成し、二次転写ローラ４にて中間転写ベルト１０上のトナー像を記録媒体Ｓ上に二次転写する。   In accordance with the timing of image formation, the leading edge of the recording medium S is fed from the paper feed cassette 8 by the paper feed roller 7 and conveyed to the registration roller 6 and temporarily stops. Then, the sheet is conveyed between the secondary transfer roller 4 and the intermediate transfer belt 1 while taking timing with the image forming operation. Here, the intermediate transfer belt 1 and the support roller 1b, which is a secondary transfer counter roller, form a so-called secondary transfer nip across the recording medium S, and the toner image on the intermediate transfer belt 10 is formed by the secondary transfer roller 4. Is secondarily transferred onto the recording medium S.

画像転写後の記録媒体Ｓは定着装置５へと送り込まれ、定着部材加熱手段５３を有し、温度制御手段１００によって表面を所定の温度に維持された定着部材５１、定着部材５１に対向し定着部材５１に圧接される加圧部材５２により形成されるニップ部に用紙を挟持搬送することで用紙上のトナー像を加熱加圧し用紙に定着させる。またニップ部から排出された用紙は、排紙ローラ３から機外に排出される。一方、画像転写後の中間転写ベルト１は、中間転写体クリーニング装置１２で、画像転写後に中間転写ベルト１上に残留する残留トナーを除去し、タンデム画像形成部による再度の画像形成に備える。   The recording medium S after the image transfer is sent to the fixing device 5 and has a fixing member heating unit 53. The fixing member 51 whose surface is maintained at a predetermined temperature by the temperature control unit 100 is opposed to the fixing member 51 and fixed. The sheet is nipped and conveyed to the nip portion formed by the pressure member 52 pressed against the member 51, whereby the toner image on the sheet is heated and pressed to be fixed on the sheet. Further, the sheet discharged from the nip portion is discharged from the discharge roller 3 to the outside of the apparatus. On the other hand, the intermediate transfer belt 1 after the image transfer is removed by the intermediate transfer body cleaning device 12 to remove residual toner remaining on the intermediate transfer belt 1 after the image transfer, so that the tandem image forming unit prepares for another image formation.

次に定着装置５について説明する。以下ローラを使用した定着装置について説明するがローラを使用する定着装値に限定されず、例えばベルトを使用する定着装置に適用することができる。   Next, the fixing device 5 will be described. Hereinafter, a fixing device using a roller will be described, but the fixing device is not limited to a fixing device using a roller, and can be applied to a fixing device using a belt, for example.

図２は実施例に係る定着装置を示す断面図である。定着装置５は、定着部材５１と加圧部材５２は対向し図示しない加圧部材により押圧されニップ部を形成している。定着部材５１は、定着部材５１を加熱するための定着部材加熱手段５３を内蔵すると共に、周囲に定着部材５１の温度を検知する定着部材温度検知手段としての温度検知部材５７を配置している。また、加圧部材５２は、加圧部材５２を加熱するための加圧部材加熱手段５４を内蔵すると共に、周囲に加圧部材５２の温度を検知する加圧部材温度検知手段としての２つの温度検知部材５５，５６を配置している。ここで、温度検知部材５５は、ニップ部に対して上流側に、温度検知部材５６はニップ部を挟んで下流側に配置する。   FIG. 2 is a cross-sectional view illustrating the fixing device according to the embodiment. In the fixing device 5, the fixing member 51 and the pressure member 52 face each other and are pressed by a pressure member (not shown) to form a nip portion. The fixing member 51 incorporates a fixing member heating unit 53 for heating the fixing member 51, and a temperature detection member 57 as a fixing member temperature detection unit for detecting the temperature of the fixing member 51 is disposed around the fixing member 51. The pressure member 52 has a built-in pressure member heating means 54 for heating the pressure member 52 and has two temperatures as pressure member temperature detection means for detecting the temperature of the pressure member 52 around the pressure member 52. Detection members 55 and 56 are arranged. Here, the temperature detection member 55 is disposed upstream of the nip portion, and the temperature detection member 56 is disposed downstream of the nip portion.

これらの温度検知部材５７、温度検知部材５５，５６は、温度制御手段１００に接続されており、温度制御手段１００はこれらの検知結果に基づいて定着部材加熱手段５３及び加圧部材加熱手段５４の給電のＯＮ／ＯＦＦを制御することにより定着部材５１の表面温度を狙いの温度である設定温度に保つ。なお、この例では定着部材加熱手段５３及び加圧部材加熱手段５４は、ハロゲンヒータとし、温度検知部材５５，５６，５７は非接触式としたが、これらは他の手段であってもよい。   The temperature detection member 57 and the temperature detection members 55 and 56 are connected to the temperature control means 100, and the temperature control means 100 determines whether the fixing member heating means 53 and the pressure member heating means 54 are based on the detection results. By controlling ON / OFF of power feeding, the surface temperature of the fixing member 51 is maintained at a set temperature which is a target temperature. In this example, the fixing member heating unit 53 and the pressure member heating unit 54 are halogen heaters, and the temperature detection members 55, 56, and 57 are non-contact types, but these may be other units.

温度制御手段１００は、設定温度となるよう前記定着部材加熱手段５３，加圧部材加熱手段５４の加熱を制御する。温度制御手段１００は、ＣＰＵ、ＲＡＭ、ＲＯＭ等を備えたマイクロコンピュータで構成され、前記温度検知部材５５，５６，５７からの検出温度、設定された温度を入力信号として、所定の制御プログラムを実行して定着部材加熱手段５３及び加圧部材加熱手段５４のＯＮ・ＯＦＦ制御を行う。   The temperature control unit 100 controls the heating of the fixing member heating unit 53 and the pressure member heating unit 54 so as to reach a set temperature. The temperature control means 100 is composed of a microcomputer equipped with a CPU, RAM, ROM, etc., and executes a predetermined control program using the detected temperature from the temperature detecting members 55, 56, 57 and the set temperature as input signals. Then, ON / OFF control of the fixing member heating unit 53 and the pressure member heating unit 54 is performed.

ここで、加圧部材５２の構造について説明する。図３は加圧部材の詳細な構造を示す断面図である５２。加圧部材５２は、金属管等により形成される基材５２ａの外周にシリコンゴム等の弾性体よりなるゴム層５２ｂを設けて構成される。また最外周をなすゴム層５２ｂの表面は、トナーとの離型性を確保するためにＰＦＡ等のフッ素系樹脂を被服することができる。   Here, the structure of the pressure member 52 will be described. FIG. 3 is a sectional view 52 showing the detailed structure of the pressure member. The pressing member 52 is configured by providing a rubber layer 52b made of an elastic body such as silicon rubber on the outer periphery of a base material 52a formed of a metal tube or the like. The surface of the rubber layer 52b that forms the outermost periphery can be coated with a fluorine-based resin such as PFA in order to ensure releasability from the toner.

上述のように加圧部材５２は定着部材５１と圧接されニップ部を形成するためにゴム層５２ｂを有している。ニップを必要な幅確保するためにはゴム層５２ｂの厚みを増すことが有効であるが、その結果として加圧部材５２は高熱容量となることが多い。加圧力に対して変形せずに形状保持するためには基材５２ａ（一般的には金属、概ね鉄系）もある程度の厚みが必要である。その結果加圧部材５２の熱容量は大きくならざるを得ない。   As described above, the pressure member 52 is in pressure contact with the fixing member 51 and has the rubber layer 52b to form a nip portion. In order to secure the necessary width of the nip, it is effective to increase the thickness of the rubber layer 52b. As a result, the pressure member 52 often has a high heat capacity. In order to maintain the shape without deformation with respect to the applied pressure, the base material 52a (generally metal, generally iron-based) also needs a certain thickness. As a result, the heat capacity of the pressure member 52 must be increased.

また定着処理の基本性能に大きく寄与するのは、定着部材５１の温度である。これは、定着性、ウォームアップタイム、温度維持等定着部材温度を第一に考える必要があるためである。そのため定着部材５１の熱容量は小さくする必要があるとともに、定着部材５１の定着部材加熱手段５３には大きい電力を供給する必要がある。一方装置全体に使用できる電力は決まっており（省エネの観点からなるべく小さいことが好ましい）その加圧部材加熱手段５４には十分な熱量が与えることができない場合が多い。以上のことから加圧部材５２の熱応答性は悪くならざるを得ない。   The temperature of the fixing member 51 greatly contributes to the basic performance of the fixing process. This is because it is necessary to first consider the fixing member temperature such as fixing property, warm-up time, and temperature maintenance. Therefore, it is necessary to reduce the heat capacity of the fixing member 51 and to supply a large amount of electric power to the fixing member heating unit 53 of the fixing member 51. On the other hand, the power that can be used for the entire apparatus is determined (preferably as small as possible from the viewpoint of energy saving), and in many cases, a sufficient amount of heat cannot be applied to the pressure member heating means 54. From the above, the thermal responsiveness of the pressure member 52 must be deteriorated.

加圧部材５２の表面温度による転写紙カール、定着性への影響があるので設定温度に制御することが重要であるが、加圧部材５２は、熱容量が大きいため狙いの温度である設定温度に制御することが難しい。特に加圧部材５２を室温の状態から温めるウォームアップ直後は上記傾向が顕著である。   Since the surface temperature of the pressure member 52 has an effect on the transfer paper curl and fixing property, it is important to control the set temperature. However, since the pressure member 52 has a large heat capacity, the target temperature is set to a target temperature. Difficult to control. In particular, the above tendency is remarkable immediately after the warm-up in which the pressure member 52 is heated from the room temperature.

この傾向について説明する。図４はウォームアップ時における定着部材と加圧部材の温度を示すグラフである。図４に示すように、加圧部材５２には温度の落ち込みが発生する。符号Ｊで示す線は加圧部材５２を加圧部材加熱手段５４だけで温めた場合の温度推移とほぼ等しくなり、加圧部材５２の温度の実態を正確に捉えている。一方、符号Ｋで示す線は定着部材５１からの熱量を表面から得るため実態よりも高く推移している。その結果加圧部材５２の目標到達温度に実態よりも早く到達し立ち上げ動作完了し回転停止する。回転を停止すると定着部材５１からの熱供給がなくなるので加圧部材５２の表面温度は低下を始め、Ｊに示す実態温度と均衡が取れた時点でＪと同じ温度となる。この見かけ上の温度により立ち上げ完了した状態（Ｍに示す期間）に印刷するとニップ部で転写紙に熱を奪われると加圧部材５２温度が低下し転写紙カールが大きくなってしまう。本例ではこのようなウォームアップ直後の不具合を防止するためにウォームアップ時に効率よく確実に加圧部材５２を温める。   This tendency will be described. FIG. 4 is a graph showing the temperatures of the fixing member and the pressure member during warm-up. As shown in FIG. 4, a temperature drop occurs in the pressure member 52. The line indicated by the symbol J is substantially equal to the temperature transition when the pressurizing member 52 is heated only by the pressurizing member heating means 54, and accurately captures the actual temperature of the pressurizing member 52. On the other hand, the line indicated by the symbol K is higher than the actual condition because the amount of heat from the fixing member 51 is obtained from the surface. As a result, the target temperature of the pressure member 52 is reached earlier than the actual temperature, the start-up operation is completed, and the rotation is stopped. When the rotation is stopped, the heat supply from the fixing member 51 is lost, so the surface temperature of the pressure member 52 starts to decrease and reaches the same temperature as J when the actual temperature shown in J is balanced. If printing is performed in a state where the start-up is completed by this apparent temperature (period indicated by M), when the transfer paper is deprived of heat at the nip portion, the temperature of the pressure member 52 decreases and the transfer paper curl increases. In this example, in order to prevent such a problem immediately after the warm-up, the pressure member 52 is warmed efficiently and surely during the warm-up.

次に実施例に係る定着装置の温度制御について説明する。まず、立ち上げ動作時について説明する。立ち上げ動作時は定着部材加熱手段５３、加圧部材加熱手段５４に給電する。定着部材５１、加圧部材５２は温度均一化のために回転状態とする。なお、ベルト定着方式の場合はベルトを均一に温めるために回転が必要となる。   Next, temperature control of the fixing device according to the embodiment will be described. First, the startup operation will be described. During the start-up operation, power is supplied to the fixing member heating unit 53 and the pressure member heating unit 54. The fixing member 51 and the pressure member 52 are rotated to make the temperature uniform. In the case of the belt fixing method, rotation is required to uniformly warm the belt.

このときの加圧部材５２のゴム層の内側から外側への温度変化の状態は以下のとおりである。図５は加圧部材内周面から外周面までの温度分布を示すグラフ、図６は加圧部材のゴム層の断面図、図７は定着部材と加圧部材の表面温度の推移を示すグラフである。   The state of temperature change from the inside to the outside of the rubber layer of the pressure member 52 at this time is as follows. 5 is a graph showing the temperature distribution from the inner peripheral surface to the outer peripheral surface of the pressure member, FIG. 6 is a cross-sectional view of the rubber layer of the pressure member, and FIG. 7 is a graph showing the transition of the surface temperature of the fixing member and the pressure member. It is.

加圧部材５２が室温状態にあるときから、定着部材５１及び加圧部材５２の加熱を開始する。定着部材５１のほうが熱容量小さく、定着部材加熱手段５３の電力も大きいため定着部材５１のほうが早く昇温する。一方加圧部材５２は内部の加圧部材加熱手段５４から温められると同時に定着部材５１と接している表面からも熱量を得て昇温する。このときの加圧部材５２内の温度分布は図５に示すとおりである。加熱前は内周面、外周面ともに室温である（（Ａ）の状態）。加熱が始まると熱を受けている内周面と外周面の温度が上昇するが挟まれた内側の温度上昇は遅れる（（Ｂ）の状態）。   When the pressure member 52 is at room temperature, heating of the fixing member 51 and the pressure member 52 is started. Since the fixing member 51 has a smaller heat capacity and the electric power of the fixing member heating means 53 is larger, the temperature of the fixing member 51 rises faster. On the other hand, the pressure member 52 is heated from the internal pressure member heating means 54 and at the same time, obtains heat from the surface in contact with the fixing member 51 and raises the temperature. The temperature distribution in the pressure member 52 at this time is as shown in FIG. Before heating, the inner and outer peripheral surfaces are at room temperature (state (A)). When heating is started, the temperature of the inner and outer peripheral surfaces receiving heat rises, but the temperature rise inside is delayed (state (B)).

一方温度検知は外周面のみで行うため、図５の（Ｃ）に示すような、外周面温度検知部材が設定温度を検知したときの温度分布となる。ところが、実際に必要な熱量は待機時等温度が釣り合った状態である。同図（Ｄ）の状態を想定して外周面温度を決めており（Ｃ）の状態では蓄熱が十分にされていない。ここで、（Ｃ）と（Ｄ）で囲まれた斜線部分が蓄熱の不足両を表す。   On the other hand, since temperature detection is performed only on the outer peripheral surface, the temperature distribution is as shown in FIG. 5C when the outer peripheral surface temperature detection member detects the set temperature. However, the amount of heat actually required is in a state where the temperature is balanced such as during standby. Assuming the state of FIG. 4D, the outer peripheral surface temperature is determined, and in the state of FIG. Here, the hatched portion surrounded by (C) and (D) represents both of the shortage of heat storage.

この蓄熱不十分な状態で通紙開始する場合加圧部材の熱量が不足して、カール、定着不良等の不具合発生してしまう、これを回避するために加圧部材５２の外周面温度が定着部材５１から得る熱量によって見かけ上、上昇している分を見積もることで加圧部材５２の蓄熱量を正確に把握する。   When paper is started in a state where heat storage is insufficient, the amount of heat of the pressure member is insufficient, and problems such as curling and fixing failure occur. To avoid this, the outer peripheral surface temperature of the pressure member 52 is fixed. The amount of heat stored in the pressurizing member 52 is accurately grasped by estimating the amount that is apparently increased by the amount of heat obtained from the member 51.

本例では、加圧部材５２には、２つの温度検知部材５５，５６を設けている。ニップ部に対して上流側の温度検知部材５５の検知温度をＴｂ、下流側の温度検知部材５６の検知温度をＴｃとする。前述のように加圧部材５２は内部の加圧部材加熱手段５４から温められると同時に定着部材５１と接している表面からも熱量を得ている。回転中ＴｂからＴｃの区間（ニップを通過する）では内面と定着部材５１の両方から熱を受ける、一方ＴｃからＴｂの区間は内面からの熱量のみで昇温する。   In this example, the pressure member 52 is provided with two temperature detection members 55 and 56. The detection temperature of the temperature detection member 55 on the upstream side with respect to the nip portion is Tb, and the detection temperature of the temperature detection member 56 on the downstream side is Tc. As described above, the pressure member 52 is heated from the internal pressure member heating means 54 and at the same time obtains heat from the surface in contact with the fixing member 51. During the rotation, the section from Tb to Tc (passing through the nip) receives heat from both the inner surface and the fixing member 51, while the section from Tc to Tb is heated only by the amount of heat from the inner surface.

ここで、この両区間の昇温の差をウォームアップ期間中について積分した値Σ〔（Ｔｃ−Ｔｂ）・ｔ〕・ｋ１が定着部材５１から受け取っている熱量と比例関係にあると考えられる。この熱量が図７のＥに示す外周面の温度差にあたる。この関係は定着部材５１、加圧部材５２、ニップ幅等により左右され決まる機器固有の定数を乗じた値になると考えられ、この定数ｋ１を実験から求め次式に当てはめることで前述の表面上昇分を求めることが可能となる。温度制御手段１００は、このように求めた表面上昇分を加圧部材の待機温度に加算して定着部材加熱手段５３及び加圧部材加熱手段５４を加熱することで十分な蓄熱量を得ることができる。   Here, it is considered that a value Σ [(Tc−Tb) · t] · k1 obtained by integrating the difference in temperature rise between the two sections during the warm-up period is proportional to the amount of heat received from the fixing member 51. This amount of heat corresponds to the temperature difference of the outer peripheral surface shown in E of FIG. This relationship is considered to be a value obtained by multiplying a constant peculiar to the device that is determined by the fixing member 51, the pressure member 52, the nip width, and the like. Can be obtained. The temperature control unit 100 can obtain a sufficient amount of heat storage by adding the surface rise obtained in this way to the standby temperature of the pressure member and heating the fixing member heating unit 53 and the pressure member heating unit 54. it can.

同様な考え方を定着部材５１の温度検知部材５７について適用する。定着部材５１から加圧部材５２へ移動する熱量は定着部材５１と加圧部材５２の温度差と比例関係にある。そこで同様に温度検知部材５７の検知温度をＴａとしＴａと加圧部材との温度差を考える。ことのき加圧部材の温度としてＴｂ、Ｔｃどちらを用いることも可能である。またＴｂとＴｃの平均値を用いることも可能である。ここでは一例として平均値（Ｔｂ＋Ｔｃ）／２を用いて考える。（Ｔｂ＋Ｔｃ）／２をウォームアップ期間中について積分した値Σ〔Ｔａ−（Ｔｂ＋Ｔｃ）／２・ｔ〕・ｋ２が定着部材５１から受け取っている熱量と比例関係にあると考えられる。   A similar concept is applied to the temperature detection member 57 of the fixing member 51. The amount of heat transferred from the fixing member 51 to the pressure member 52 is proportional to the temperature difference between the fixing member 51 and the pressure member 52. Therefore, similarly, the detection temperature of the temperature detection member 57 is Ta, and the temperature difference between Ta and the pressure member is considered. It is possible to use either Tb or Tc as the temperature of the pressure member. It is also possible to use an average value of Tb and Tc. Here, an average value (Tb + Tc) / 2 is considered as an example. A value Σ [Ta− (Tb + Tc) / 2 · t] · k2 obtained by integrating (Tb + Tc) / 2 during the warm-up period is considered to be proportional to the amount of heat received from the fixing member 51.

この関係は定着部材、加圧部材、ニップ幅等により左右され決まる機器固有の定数ｋ２を乗じた値になると考えられ、この定数ｋ２を実験から求め次式に当てはめることで前述の表面上昇分を求めることが可能となる。このように求めた表面上昇分を加圧部材の待機温度に加算して加熱することで十分な蓄熱量を得ることができる。これは定着部材５１と加圧部材５２の温度推移を示す図７のＥに示す部分の加圧部材５２の設定温度アップ分である。   This relationship is considered to be a value obtained by multiplying a constant k2 inherent to the device, which is determined by the fixing member, the pressure member, the nip width, and the like. The constant k2 is obtained from an experiment and applied to the following equation to obtain the above-described surface rise. It can be obtained. A sufficient amount of heat storage can be obtained by adding the surface rise thus obtained to the standby temperature of the pressure member and heating. This is an increase in the set temperature of the pressure member 52 in the portion indicated by E in FIG. 7 showing the temperature transition of the fixing member 51 and the pressure member 52.

早く加圧部材５２に蓄熱するためには、定着部材５１の熱量を有効に使うことが考えられる。定着部材５１の温度を本来定着部材５１に必要な温度以上に加熱する。これは定着部材の熱容量が小さいことに加えて加熱源の容量が大きいため効率よく温度を上げられるので、加圧加熱部材から加圧部材に与える熱量を減らすことなく達成できる（前述のように加圧加熱源の容量は定着加熱源の容量よりも小さい、加圧加熱源をフル点灯している場合でも、通常定着加熱源に電力投入できる余裕がある）。そのような高い温度を維持しているので定着部材と加圧部材の温度差が大きい状態で接触回転されることで定着部材から加圧部材への熱の移動量を増やし、結果として加圧部材全体の蓄熱を早くできる。その場合のウォームアップ時の定着部材の温度挙動を図７のＦに示す。   In order to quickly store heat in the pressure member 52, it is conceivable to use the heat amount of the fixing member 51 effectively. The temperature of the fixing member 51 is heated to a temperature that is necessary for the fixing member 51. This can be achieved without reducing the amount of heat applied from the pressure heating member to the pressure member because the heat capacity of the heating source is large in addition to the small heat capacity of the fixing member, so that the temperature can be increased efficiently (as described above). The capacity of the pressure heating source is smaller than the capacity of the fixing heating source, and even when the pressure heating source is fully lit, there is a margin that power can be normally applied to the fixing heating source). Since such a high temperature is maintained, the amount of heat transferred from the fixing member to the pressure member is increased by contact rotation with a large temperature difference between the fixing member and the pressure member. As a result, the pressure member Overall heat storage can be done quickly. FIG. 7F shows the temperature behavior of the fixing member during warm-up in that case.

ウォームアップ時に定着部材温度は加圧部材温度よりも早く上昇する。その結果定着部材が通常の目標温度に達した時点で加圧部材は目標温度に到達していない。そこで定着部材は通常の目標温度を過ぎても加熱を継続し所定の加算温度を目指して加熱し、さらに加算温度に到達後は少なくとも加圧部材が目標温度に到達するまで加算温度を維持する。このように制御することで加圧部材は定着部材からもらう熱量が増え結果として早く蓄熱できる。   During the warm-up, the fixing member temperature rises faster than the pressure member temperature. As a result, when the fixing member reaches the normal target temperature, the pressure member has not reached the target temperature. Therefore, the fixing member continues to be heated even after the normal target temperature has passed, and is heated toward a predetermined additional temperature. After the additional temperature is reached, the additional temperature is maintained until at least the pressure member reaches the target temperature. By controlling in this way, the pressure member increases the amount of heat received from the fixing member, and as a result, heat can be stored quickly.

このときの加圧部材内部の温度分布を図８に示す。図８中斜線に示す部分が温度加算した定着部材から得た熱量であり、全体として蓄熱量が増えている。ただし、加圧部材表面のみ加熱される状態となっているため、前述の通り表面部分温度差を蓄熱量に盛り込んで考える必要がある。これは前述の蓄熱量積分値の計算から算出可能である。   The temperature distribution inside the pressure member at this time is shown in FIG. The shaded portion in FIG. 8 is the amount of heat obtained from the fixing member obtained by adding the temperatures, and the amount of stored heat increases as a whole. However, since only the surface of the pressurizing member is heated, it is necessary to consider the surface partial temperature difference in the heat storage amount as described above. This can be calculated from the calculation of the heat storage amount integral value described above.

定着部材５１及び加圧部材５２が設定の温度に到達しウォームアップ動作が終了したときに加圧部材の蓄熱は十分であり直ぐに通紙開始した場合においても加圧部材は狙いの設定表面温度を維持できる。一方ウォームアップ動作が終了し印刷要求がない場合は回転を停止し装置は待機状態となる。   When the fixing member 51 and the pressure member 52 reach the set temperature and the warm-up operation is finished, the pressure member has sufficient heat storage, and the pressure member keeps the target set surface temperature even when the sheet starts to pass immediately. Can be maintained. On the other hand, when the warm-up operation is finished and there is no print request, the rotation is stopped and the apparatus enters a standby state.

このとき定着部材表面からの熱量がなくなるので加圧部材はその内部の加圧加熱部材からの熱量によって温度維持される。従って表面内面から加熱された状態から内面の熱による加熱へ遷移していく温度分布を考慮して蓄熱量を制御しながら加圧部材加算分を減らして通常待機温度に戻す必要がある。急に待機温度を戻した場合、外周面のみ高温状態が残っていると図５（Ｃ）の状態となり蓄熱不足となる。   At this time, since the amount of heat from the surface of the fixing member disappears, the temperature of the pressure member is maintained by the amount of heat from the pressure heating member inside. Therefore, it is necessary to reduce the amount added to the pressurizing member and return to the normal standby temperature while controlling the amount of heat storage while taking into account the temperature distribution that transitions from the state heated from the inner surface to the heating by the inner surface. When the standby temperature is suddenly returned, if the high temperature state remains only on the outer peripheral surface, the state shown in FIG.

図９に示すように外周面温度はＤ、Ｇ、Ｃの順に温度分布は定常状態Ｃに戻っていくので、ウォームアップ直後に加算した設定温度をｄとしたときに時間経過とともに設定温度ｇからｃと変化させることで全体の蓄熱量を一定に保ったまま定常の待機状態に戻すことができる。   As shown in FIG. 9, since the temperature distribution of the outer peripheral surface returns to the steady state C in the order of D, G, and C, when the set temperature added immediately after warm-up is d, By changing to c, it is possible to return to a steady standby state while keeping the entire heat storage amount constant.

以上説明したように本実施例によれば、ウォームアップ直後の通紙においても加圧部材の温度が落ち込むことを防止し加熱部材及び加圧部材間の温度差を所定の範囲に維持でき、ウォームアップ直後の通紙開始から連続通紙を通じてカール量の低減、定着性の確保を図ることができる。   As described above, according to the present embodiment, the temperature of the pressure member can be prevented from dropping even when the paper is passed immediately after warm-up, and the temperature difference between the heating member and the pressure member can be maintained within a predetermined range. The curling amount can be reduced and the fixing property can be ensured through the continuous paper feeding from the start of the paper feeding immediately after the up.

１ 中間転写ベルト
１ａ、１ｂ 支持ローラ
１ａ、１ｂ 支持ローラ
２Ｙ，２Ｃ，２Ｍ，２Ｋ トナーボトル
３ 排紙ローラ
４ 二次転写ローラ
５ 定着装置
６ レジストローラ
７ 給紙コロ
８ 給紙カセット
９ 光書込ユニット
１０ 中間転写ベルト
１０Ｙ，１０Ｃ，１０Ｍ，１０Ｋ 現像装置
１１Ｙ，１１Ｃ，１１Ｍ，１１Ｋ 一次転写装置
１２ 中間転写体クリーニング装置
１７Ｙ，１７Ｃ，１７Ｍ，１７Ｋ 帯電装置
５１ 定着部材
５２ 加圧部材
５２ａ 基材
５２ｂ ゴム層
５３ 定着部材加熱手段
５４ 加圧部材加熱手段
５５，５６ 温度検知部材（加圧部材温度検知手段）
５７ 温度検知部材（定着部材温度検知手段）
１００ 温度制御手段
１０１Ｙ、１０１Ｃ、１０１Ｍ、１０１Ｋ 画像形成手段 DESCRIPTION OF SYMBOLS 1 Intermediate transfer belt 1a, 1b Support roller 1a, 1b Support roller 2Y, 2C, 2M, 2K Toner bottle 3 Paper discharge roller 4 Secondary transfer roller 5 Fixing device 6 Registration roller 7 Paper feed roller 8 Paper feed cassette 9 Optical writing Unit 10 Intermediate transfer belt 10Y, 10C, 10M, 10K Developing device 11Y, 11C, 11M, 11K Primary transfer device 12 Intermediate transfer member cleaning device 17Y, 17C, 17M, 17K Charging device 51 Fixing member 52 Pressure member 52a Base member 52b Rubber layer 53 Fixing member heating means 54 Pressure member heating means 55, 56 Temperature detection member (pressure member temperature detection means)
57 Temperature detection member (fixing member temperature detection means)
100 Temperature control means 101Y, 101C, 101M, 101K Image forming means

特開平１０−２５４２８１号公報JP-A-10-254281 特開２００５−３４５４８８号公報JP 2005-345488 A

Claims (6)

互いに対向する一対の定着部材及び加圧部材により転写紙を挟み込み、熱および圧力を加えてトナー像を前記転写紙上に定着させる定着装置において、
前記定着部材を加熱する定着部材加熱手段と、
定着部材の温度を検出する少なくとも１つの定着部材温度検知手段と、
前記加圧部材を加熱する加圧部材加熱手段と、
前記加圧部材の温度を検出する少なくとも２つの加圧部材温度検知手段と、
前記加圧部材温度検知手段は定着部材と加圧部材から形成されるニップ部の上流と下流とにそれぞれ配置されており、
前記加圧部材の温度制御を前記定着部温度検知手段及び加圧部温度検知手段に基づいて行う温度制御手段を備えることを特徴とする定着装置。 In a fixing device that sandwiches a transfer paper between a pair of fixing members and a pressure member facing each other and applies heat and pressure to fix the toner image on the transfer paper.
Fixing member heating means for heating the fixing member;
At least one fixing member temperature detecting means for detecting the temperature of the fixing member;
A pressure member heating means for heating the pressure member;
At least two pressure member temperature detecting means for detecting the temperature of the pressure member;
The pressure member temperature detecting means is disposed upstream and downstream of a nip formed by the fixing member and the pressure member, respectively.
A fixing device comprising: a temperature control unit that performs temperature control of the pressure member based on the fixing unit temperature detection unit and the pressure unit temperature detection unit. 前記温度制御手段は、前記加圧部材温度検知手段における上流側の検知温度Ｔｂ、下流側の検知温度Ｔｃ、ウォームアップに要する時間ｔとし、Ｔｃ−Ｔｂをウォームアップ中の期間中積分した値に機器固有の定数ｋ１を乗じた値Σ〔（Ｔｃ−Ｔｂ）・ｔ〕・ｋ１に基づいてウォームアップ直後における加圧部材待機時設定温度を通常における加圧部材待機時設定温度よりも高く設定することを特徴とする請求項１記載の定着装置。   The temperature control means has an upstream detection temperature Tb, a downstream detection temperature Tc, and a time t required for warm-up in the pressurizing member temperature detection means, and Tc−Tb is integrated during the warm-up period. Based on a value Σ [(Tc−Tb) · t] · k1 multiplied by a constant k1 unique to the device, the pressure member standby set temperature immediately after warm-up is set higher than the normal pressure member standby set temperature. The fixing device according to claim 1. 前記温度制御手段は、前記加圧部材の温度検知手段における上流側の検知温度Ｔｂ、下流側の検知温度Ｔｃ、定着部材の検知温度Ｔａ、ウォームアップに要する時間をｔとし、Ｔａ−（Ｔｃ＋Ｔｂ）／２をウォームアップ中の期間中積分した値に機器固有の定数ｋ２を乗じた値Σ〔Ｔａ−（Ｔｃ＋Ｔｂ）／２・ｔ〕・ｋ２に応じてウォームアップ直後の加圧部材待機時設定温度を通常の加圧部材待機時設定温度よりも高く設定することを特徴とする請求項１記載の定着装置。   The temperature control means sets the upstream detection temperature Tb, the downstream detection temperature Tc, the detection temperature Ta of the fixing member, and the time required for warming up to t− (Tc + Tb) in the temperature detection means of the pressure member. / 2 is multiplied by a constant k2 inherent to the device during the warm-up period Σ [Ta− (Tc + Tb) / 2 · t] · k2 in accordance with the set temperature at the time of waiting for the pressure member immediately after the warm-up The fixing device according to claim 1, wherein the fixing device is set to be higher than a normal pressure member standby temperature setting. 前記温度制御手段は、ウォームアップ中の定着部材の第一の目標温度、第二の目標温度を設定し、ウォームアップ中に第一の目標温度に到達した時点で加圧部材温度が加圧部材待機時設定温度に加算分を加えた温度に到達していない場合、定着部材を第二の目標温度まで加熱継続することを特徴とする請求項１から請求項３までの何れか一項に記載の定着装置。   The temperature control means sets a first target temperature and a second target temperature of the fixing member during warm-up, and when the first target temperature is reached during warm-up, the pressure member temperature is increased by the pressure member. The heating of the fixing member to the second target temperature is continued when the temperature obtained by adding the added amount to the standby set temperature is not reached. Fixing device. 前記温度制御手段は、ウォームアップ中の定着部材の第一の目標温度、第二の目標温度を設定し、ウォームアップ中に第一の目標温度に到達した時点で加圧部材温度が加圧部材待機時設定温度に加算分を加えた温度に到達していない場合、定着部材を第二の目標温度まで加熱継続し、加圧部材が加圧部材待機時設定温度に加算分を加えた温度に到達した後に加算分を段階的に戻すことを特徴とする請求項１から請求項４までの何れか一項に記載の定着装置。   The temperature control means sets a first target temperature and a second target temperature of the fixing member during warm-up, and when the first target temperature is reached during warm-up, the pressure member temperature is increased by the pressure member. If the temperature has not reached the standby set temperature plus the added temperature, the fixing member will continue to be heated to the second target temperature, and the pressurizing member will add the added pressure to the pressurized member standby set temperature. The fixing device according to claim 1, wherein after the arrival, the added amount is returned in a stepwise manner. 請求項１から請求項５までの何れか一項に記載の定着装置を備えることを特徴とする画像形成装置。   An image forming apparatus comprising the fixing device according to claim 1.