JP6938117B2

JP6938117B2 - Image forming device

Info

Publication number: JP6938117B2
Application number: JP2016121433A
Authority: JP
Inventors: 高木　修; 修高木; 菊地　和彦; 和彦菊地; 智絵宮内
Original assignee: Toshiba Corp; Toshiba TEC Corp
Current assignee: Toshiba Corp; Toshiba TEC Corp
Priority date: 2016-06-20
Filing date: 2016-06-20
Publication date: 2021-09-22
Anticipated expiration: 2036-06-20
Also published as: JP2017227664A

Description

一実施形態は画像形成装置に関する。 One embodiment relates to images forming device.

トナーには定着温度域が存在するため、トナー像の定着では温度センサによりベルト表面の温度を監視して、定着ベルトの温度を目標温度に合わせる（例えば特許文献１参照）。 Since the toner has a fixing temperature range, in fixing the toner image, the temperature of the belt surface is monitored by a temperature sensor, and the temperature of the fixing belt is adjusted to the target temperature (see, for example, Patent Document 1).

従来、セラミック基板上で複数の発熱体を基板長手方向に配置したヒータが知られており（例えば特許文献２参照）、このヒータを使った定着装置は複数個の発熱体を基板長手方向にグループ化してそれぞれ複数個の発熱体からなる複数の発熱体群毎に加熱駆動する。 Conventionally, a heater in which a plurality of heating elements are arranged in the longitudinal direction of the substrate on a ceramic substrate is known (see, for example, Patent Document 2), and a fixing device using this heater groups a plurality of heating elements in the longitudinal direction of the substrate. It is heated and driven for each of a plurality of heating element groups each consisting of a plurality of heating elements.

印字範囲の大きさに応じて発熱体群を選択駆動する場合、ヒータ表面上の温度は複数の発熱体群の間で均一にする必要がある。ヒータ表面上の温度が均一である場合、ニップ部での加熱によってトナーが用紙に接触するトナー界面での温度は数秒で８０℃以上の定着可能温度に到達する（例えば特許文献３参照）。定着ベルトのベルト裏面温度はニップ部においてヒータにより急激に上昇し、その反対側のベルト表面温度はニップ部で熱交換により急激に下降する。ベルト表面温度はベルト裏面よりヒータから熱を供給されるため、定着ベルトが下流側を周回してニップ部の上流に戻ってくる間に上昇する。画像品質を保つ上で、ベルト部位がニップ部の上流に戻ってくる度にベルト表面温度が目標温度になっていることを監視する必要がある。 When the heating element group is selectively driven according to the size of the printing range, the temperature on the heater surface needs to be uniform among the plurality of heating element groups. When the temperature on the surface of the heater is uniform, the temperature at the toner interface where the toner comes into contact with the paper due to heating at the nip portion reaches a fixable temperature of 80 ° C. or higher in a few seconds (see, for example, Patent Document 3). The belt back surface temperature of the fixing belt rises sharply at the nip portion due to the heater, and the belt surface temperature on the opposite side sharply drops due to heat exchange at the nip portion. Since the belt surface temperature is supplied with heat from the heater from the back surface of the belt, it rises while the fixing belt goes around the downstream side and returns to the upstream of the nip portion. In order to maintain the image quality, it is necessary to monitor that the belt surface temperature reaches the target temperature every time the belt part returns to the upstream of the nip part.

特開２０１０−１９９０６号公報Japanese Unexamined Patent Publication No. 2010-199006 特開２０１５−２１９４１７号公報Japanese Unexamined Patent Publication No. 2015-219417 特開２０１５−２１９４１９号公報Japanese Unexamined Patent Publication No. 2015-219419

しかし、従来、定着装置が発熱体群毎に選択加熱する構成を有する場合、発熱体群毎のベルト表面温度を把握できず、ベルト表面温度を主走査方向で均一に揃えることができない。 However, conventionally, when the fixing device has a configuration in which selective heating is performed for each heating element group, the belt surface temperature for each heating element group cannot be grasped, and the belt surface temperature cannot be uniformly aligned in the main scanning direction.

このような課題を解決するため、一実施形態に係る定着装置は、感光体ドラムと、この感光体ドラム上に潜像を形成する潜像形成部と、潜像を現像して可視化する現像器と、この現像器により可視化されたトナー像を用紙に転写する転写器と、トナー像を用紙に定着させる定着装置と、定着装置が備えるベルトのベルト表面温度の時間温度特性を表す時間温度特性情報を予め記憶したメモリと、コントローラと、を備える。定着装置は、ベルト表面およびベルト裏面を有する無端状のベルトと、このベルトの幅方向に平行な前記ベルト裏面側に位置する基板、この基板上に設けられ前記ベルト裏面に当接する発熱体、および発熱体を駆動する駆動部を有するヒータと、発熱体と前記ベルトとが当接するニップ位置よりもベルトの周回方向下流のベルト表面およびその反対側のベルト裏面の何れかに設けられた温度センサと、を備える。コントローラは、温度センサから検出温度を収集し、ベルトの周回速度、ベルトの周回径、温度センサの周位置および時間温度特性情報から、ベルトの任意の部位がニップ位置から一周して再度前記ニップ位置の上流位置に戻ってきたときのベルト表面温度を予測する。時間温度特性は、ベルトのベルト表面温度がニップ位置の通過後、一旦下がりその下がった温度から上昇し、ベルト裏面温度はニップ位置の通過後、一旦上がりその上がった温度から下降するという推移曲線で表される。温度センサは、ベルト表面温度が推移曲線上で最大となる周位置に設けられている。 In order to solve such a problem, the fixing device according to the embodiment includes a photoconductor drum, a latent image forming unit that forms a latent image on the photoconductor drum, and a developing device that develops and visualizes the latent image. A transfer device that transfers the toner image visualized by this developing device to the paper, a fixing device that fixes the toner image on the paper, and time-temperature characteristic information that represents the time-temperature characteristics of the belt surface temperature of the belt provided in the fixing device. It is provided with a memory in which the above is stored in advance and a controller. The fixing device includes an endless belt having a belt front surface and a belt back surface, a substrate located on the belt back surface side parallel to the width direction of the belt, a heating element provided on the substrate and in contact with the belt back surface, and a heating element. A heater having a drive unit for driving the heating element, and a temperature sensor provided on either the belt surface downstream of the nip position where the heating element and the belt abut in the circumferential direction of the belt or the back surface of the belt on the opposite side. , Ru equipped with. The controller collects the detected temperature from the temperature sensor, and from the belt orbital speed, the orbital diameter of the belt, the orbital position of the temperature sensor, and the time temperature characteristic information, any part of the belt goes around from the nip position and again goes around the nip position. Predict the belt surface temperature when returning to the upstream position of. Time-temperature characteristic after passing belt surface temperature of the belt of the nip position, once downward raised from the lowered temperature, after passing through the belt back surface temperature nip position, once raised by deviation curve that descends from its raised temperature expressed. The temperature sensor is provided at the circumferential position where the belt surface temperature becomes maximum on the transition curve.

また、実施形態に係る画像形成装置は、上記定着装置と、感光体ドラムと、この感光体ドラム上に潜像を形成する潜像形成部と、潜像の現像器と、この現像器により可視化されたトナー像を用紙に転写する転写器と、を備える。 Further, the image forming apparatus according to the embodiment is visualized by the fixing device, a photoconductor drum, a latent image forming unit that forms a latent image on the photoconductor drum , a latent image developer, and the developer. It is provided with a transfer device for transferring the toner image to paper.

実施の形態に係る定着装置の構成図を示す図である。It is a figure which shows the block diagram of the fixing device which concerns on embodiment. （ａ）〜（ｃ）は実施の形態に係る定着装置のヒータの上面図である。(A) to (c) are top views of the heater of the fixing device according to the embodiment. 実施の形態に係る画像形成装置の構成例を示す図である。It is a figure which shows the structural example of the image forming apparatus which concerns on embodiment. 実施の形態に係る定着装置のベルトのベルト表面温度、ベルト裏面温度を含む時間温度特性を示す線図である。It is a diagram which shows the time temperature characteristic including the belt surface temperature and the belt back surface temperature of the belt of the fixing device which concerns on embodiment. 図４の時間温度特性情報のうち一部を抜き出して示す線図である。It is a diagram which shows by extracting a part of the time temperature characteristic information of FIG. 図４の時間温度特性情報のうち一部を抜き出して示す別の線図である。It is another diagram which shows by extracting a part of the time temperature characteristic information of FIG. （ａ）〜（ｃ）は実施の形態に係る定着装置のメモリに記憶されたベルト材質に応じた時間温度特性を示す線図である。(A) to (c) are diagrams showing the time-temperature characteristics according to the belt material stored in the memory of the fixing device according to the embodiment.

以下、実施の形態に係る画像形成装置について、図１乃至図７を参照しながら説明する。尚、各図において同一箇所については同一の符号を付すとともに、重複した説明は省略する。 Hereinafter, the image forming apparatus according to the embodiment will be described with reference to FIGS. 1 to 7. In each figure, the same parts are designated by the same reference numerals, and duplicate description will be omitted.

図１は実施の形態に係る定着装置の構成例を示す図である。図２（ａ）は実施の形態に係る定着装置のヒータの上面図であり、駆動部無しのヒータ６４単体を示している。図２（ｂ）は駆動部とともにヒータ６４を示している。図２（ｃ）は発熱体群を示す上面図である。これらの図中、同じ符号は互いに同じ要素を表す。 FIG. 1 is a diagram showing a configuration example of a fixing device according to an embodiment. FIG. 2A is a top view of the heater of the fixing device according to the embodiment, and shows a single heater 64 without a drive unit. FIG. 2B shows the heater 64 together with the drive unit. FIG. 2C is a top view showing a group of heating elements. In these figures, the same reference numerals represent the same elements.

定着装置５０は、ベルト表面５１およびベルト裏面５２を有する無端状のベルト５３と、ベルト５３に対向する加圧ローラ６８とを備えている。また、定着装置５０は、ベルト５３の幅方向（ベルト幅方向）に平行なベルト裏面５２側の基板５４、この基板５４上に幅方向に設けられそれぞれベルト裏面５２に当接する複数の発熱体５５、およびそれぞれ発熱体５５を複数個含む７つの発熱体群５６、５７、５８、５９、６０、６１、６２（図２）を選択駆動するスイッチングドライバＩＣ６３（駆動部）を有するヒータ６４を備えている。更に定着装置５０は基板５４の裏面（図１左方）であって且つ発熱体群５６、５７、５８、５９、６０、６１、６２に対応した箇所にそれぞれ設けられた７個の温度センサ６５と、基板５４の位置よりもベルト５３の周回方向下流のベルト表面５１に発熱体群５６、５７、５８、５９、６０、６１、６２に対応した箇所にそれぞれ設けられた７個の温度センサ６７と、その反対側のベルト裏面５２に発熱体群５６、５７、５８、５９、６０、６１、６２に対応した箇所にそれぞれ設けられた７個の温度センサ６６とを備えている。 The fixing device 50 includes an endless belt 53 having a belt front surface 51 and a belt back surface 52, and a pressure roller 68 facing the belt 53. Further, the fixing device 50 is a substrate 54 on the belt back surface 52 side parallel to the width direction (belt width direction) of the belt 53, and a plurality of heating elements 55 provided on the substrate 54 in the width direction and in contact with the belt back surface 52, respectively. , And a heater 64 having a switching driver IC 63 (driving unit) that selectively drives seven heating element groups 56, 57, 58, 59, 60, 61, 62 (FIG. 2), each including a plurality of heating elements 55. There is. Further, the fixing device 50 is a back surface of the substrate 54 (left side in FIG. 1), and seven temperature sensors 65 provided at locations corresponding to the heating element groups 56, 57, 58, 59, 60, 61, 62, respectively. And seven temperature sensors 67 provided at locations corresponding to the heating element groups 56, 57, 58, 59, 60, 61, 62 on the belt surface 51 downstream of the position of the substrate 54 in the circumferential direction. And seven temperature sensors 66 provided at locations corresponding to the heating element groups 56, 57, 58, 59, 60, 61, 62 on the back surface 52 of the belt on the opposite side.

ベルト５３は定着ベルトであり、矢印Ｓ方向（ベルト周回方向Ｓ）に周回駆動される。ベルト５３は多層構造を有する。基層は耐熱層であり、例えばポリイミド（ＰＩ）、Ｎｉ、ステンレスが用いられる。基層の上には断熱性のシリコーンゴム層が形成される。 The belt 53 is a fixing belt, and is orbitally driven in the arrow S direction (belt circumferential direction S). The belt 53 has a multi-layer structure. The base layer is a heat-resistant layer, and for example, polyimide (PI), Ni, or stainless steel is used. A heat insulating silicone rubber layer is formed on the base layer.

加圧ローラ６８は、ベルト５３の方向に押圧され、ベルト表面５１を介してヒータ６４との間にニップ部（Ｎを付した部分参照）を形成する。加圧ローラ６８は、例えば鉄芯６９と、シリコンスポンジ層７０と、保護層７１との層構造を有する。 The pressure roller 68 is pressed in the direction of the belt 53 and forms a nip portion (see the portion with N) between the pressure roller 68 and the heater 64 via the belt surface 51. The pressure roller 68 has, for example, an iron core 69, a silicon sponge layer 70, and a protective layer 71.

ヒータ６４は、ベルト裏面５２からベルト表面５１側に熱を供給する。ヒータ６４は基板５４及び発熱体５５を備えている。基板５４はセラミック基板である。基板５４の長手方向がベルト５３の周回中心に平行に支持されている。図２（ａ）に示すように基板５４上に７つの薄膜状の発熱抵抗層７２（破線参照）が基板長手方向に一例に形成されており、隣接する発熱抵抗層７２どうしは互いに非接触である。７つの発熱抵抗層７２にはパターンニング用のアルミ層が成膜され、パターンニングの開口部から露出した発熱抵抗層７２の上面が発熱体５５を形成する。パターンニングにより基板短手方向両端部に残ったアルミ層の島部は一つの発熱体５５の電極７３、７４として機能する。 The heater 64 supplies heat from the back surface 52 of the belt to the front surface 51 of the belt. The heater 64 includes a substrate 54 and a heating element 55. The substrate 54 is a ceramic substrate. The longitudinal direction of the substrate 54 is supported parallel to the circumferential center of the belt 53. As shown in FIG. 2A, seven thin-film heat-generating resistance layers 72 (see broken lines) are formed on the substrate 54 as an example in the longitudinal direction of the substrate, and the adjacent heat-generating resistance layers 72 are not in contact with each other. be. An aluminum layer for patterning is formed on the seven heat generation resistance layers 72, and the upper surface of the heat generation resistance layer 72 exposed from the opening of the patterning forms the heating element 55. The islands of the aluminum layer remaining at both ends in the lateral direction of the substrate by patterning function as electrodes 73 and 74 of one heating element 55.

また、図２（ｂ）に示す配線例のように、発熱体５５の一方の電極７３はそれぞれスイッチング素子７５に接続され、発熱体５５の他方の電極７４は全てスイッチングドライバＩＣ６３に収容される。スイッチング素子７５は例えばＦＥＴゲートであり、スイッチングドライバＩＣ６３（駆動部）によるオン又はオフによって導通又は切断が駆動される。スイッチングドライバＩＣ６３は発熱体５５を個別に選択して駆動する。スイッチングドライバＩＣ６３は各スイッチング素子７５の切替え駆動によって１つ以上の発熱体５５を個別に通電又は切断し、ベルト５３の幅方向の発熱全領域を複数例えば７つの加熱領域に分割する。 Further, as shown in the wiring example shown in FIG. 2B, one electrode 73 of the heating element 55 is connected to the switching element 75, and all the other electrodes 74 of the heating element 55 are housed in the switching driver IC 63. The switching element 75 is, for example, an FET gate, and conduction or disconnection is driven by turning on or off by the switching driver IC 63 (driving unit). The switching driver IC 63 individually selects and drives the heating element 55. The switching driver IC 63 individually energizes or disconnects one or more heating elements 55 by switching driving of each switching element 75, and divides the entire heating region in the width direction of the belt 53 into a plurality of, for example, seven heating regions.

図２（ｃ）には７つに分割駆動された発熱体群５６、５７、５８、５９、６０、６１、６２の配置例と、用紙サイズＷ１、Ｗ２、Ｗ３、Ｗ４との関係が示されている。用紙サイズＷ１〜Ｗ４は最小サイズのはがきサイズ、ＣＤジャケットサイズ、Ｂ５Ｒサイズ、Ａ４ＲサイズあるいはＡ４サイズ長辺などに対応する。発熱体群（発熱体群）５６、５７、５８、５９、６０、６１、６２はそれぞれ抵抗値２００Ω、２００Ω、１６０Ω、３０Ω、１６０Ω、２００Ω、２００Ωの直流抵抗を持ってもよい。スイッチングドライバＩＣ６３はこれらの抵抗値を変更できるようにスイッチング回路内に内部抵抗を持つ。 FIG. 2C shows the relationship between the arrangement example of the heating element groups 56, 57, 58, 59, 60, 61, 62 divided into seven and the paper sizes W1, W2, W3, W4. ing. The paper sizes W1 to W4 correspond to the smallest postcard size, CD jacket size, B5R size, A4R size, A4 size long side, and the like. The heating element group (heating element group) 56, 57, 58, 59, 60, 61, 62 may have DC resistances having resistance values of 200Ω, 200Ω, 160Ω, 30Ω, 160Ω, 200Ω, and 200Ω, respectively. The switching driver IC 63 has an internal resistance in the switching circuit so that these resistance values can be changed.

また、図１において温度センサ６５、６６、６７は何れもサーミスタであり、測定結果を定着装置５０内のコントローラ７６へ出力する。同図の例では、温度センサ６５、６６、６７は、７つに分割された各加熱領域の数だけそれぞれベルト５３内に設けられており、一組の温度センサ６５、６６、６７だけが表示されている。一つの加熱領域について着目すると、ベルト５３の用紙との加熱接触部位が、基準となるニップ位置から周回を開始して、ニップ位置から下流へ周回し何秒か経過した後の周位置のベルト裏面５２及びベルト表面５１がそれぞれ何℃になっているかをコントローラ７６は測定している。ニップ位置とはニップ部Ｎの位置であり、ベルト５３及び加圧ローラ６８どうしが圧接されるベルト範囲を指す。「基準となるニップ位置」とは全周上で任意にとったベルト範囲の開始位置を指す。コントローラ７６は各温度センサ６５、６６、６７から検出温度を収集する。 Further, in FIG. 1, the temperature sensors 65, 66, and 67 are all thermistors, and the measurement results are output to the controller 76 in the fixing device 50. In the example of the figure, the temperature sensors 65, 66, 67 are provided in the belt 53 by the number of each heating region divided into seven, and only one set of temperature sensors 65, 66, 67 is displayed. Has been done. Focusing on one heating region, the heating contact portion of the belt 53 with the paper starts to circulate from the reference nip position, circulates downstream from the nip position, and after a few seconds have passed, the back surface of the belt at the circumferential position. The controller 76 measures the temperature of each of the 52 and the belt surface 51. The nip position is the position of the nip portion N, and refers to the belt range in which the belt 53 and the pressure roller 68 are pressure-welded to each other. The "reference nip position" refers to the start position of the belt range arbitrarily taken on the entire circumference. The controller 76 collects the detected temperature from each of the temperature sensors 65, 66, 67.

また、予め経過時間と温度との関係（図４）をシミュレーション又は実験等によりサンプリング取得しておき、この関係を表す時間温度特性情報をメモリ８２（図１）に記憶してコントローラ７６が参照可能にされている。図４に示すように、ベルト表面温度はニップ位置（ニップと図示されている）の通過中、目標温度約１７０℃から急激に下降する。また、ベルト表面温度はニップ位置で一旦下がり、その下がった温度から目標温度に向かって上昇するという推移曲線で表される。ベルト５３の表面に設けられた温度センサ６７は、ベルト表面温度がこの推移曲線上で最大となる周位置に７つ分設けられている。周位置は例えば半周に至る手前である。コントローラ７６はベルト５３の周回速度、ベルト５３の周回径、温度センサ６６、６７の周位置および時間温度特性情報からベルト表面温度を予測する。つまり、コントローラ７６は、ベルト５３の加熱接触部位がニップ部位置から下流方向へ周回し、半周に到達する前の周位置において温度センサ６６、６７が実測した温度と、図４の温度推移曲線の変化の度合いとによって、そのベルト部位が一周して再度ニップ部の上流位置に戻ってきたときの温度を予測する。コントローラ７６は温度センサ６５によってニップ位置の基板５４の裏面の温度を見ることで、ヒータ６４の温度異常を検知する。 Further, the relationship between the elapsed time and the temperature (FIG. 4) is sampled and acquired in advance by simulation or experiment, and the time-temperature characteristic information representing this relationship is stored in the memory 82 (FIG. 1) so that the controller 76 can refer to it. Has been made. As shown in FIG. 4, the belt surface temperature drops sharply from the target temperature of about 170 ° C. while passing through the nip position (shown as the nip). Further, the belt surface temperature is represented by a transition curve in which the belt surface temperature drops once at the nip position and then rises from the lowered temperature toward the target temperature. Seven temperature sensors 67 provided on the surface of the belt 53 are provided at peripheral positions where the belt surface temperature is maximum on this transition curve. The circumferential position is, for example, before reaching half a circumference. The controller 76 predicts the belt surface temperature from the orbital speed of the belt 53, the orbital diameter of the belt 53, the orbital positions of the temperature sensors 66 and 67, and the time temperature characteristic information. That is, in the controller 76, the temperature measured by the temperature sensors 66 and 67 at the circumferential position before the heating contact portion of the belt 53 orbits in the downstream direction from the nip portion position and reaches the half circumference, and the temperature transition curve of FIG. Depending on the degree of change, the temperature at which the belt portion goes around and returns to the upstream position of the nip portion is predicted. The controller 76 detects a temperature abnormality of the heater 64 by observing the temperature of the back surface of the substrate 54 at the nip position by the temperature sensor 65.

また、図１の定着装置５０は、主走査方向の発熱体群５６、５７、５８、５９、６０、６１、６２についてそれぞれ温度センサ６５、６６、６７を設けている。温度センサ６６、６７によって、コントローラ７６は各発熱体群５６、５７、５８、５９、６０、６１、６２直下のベルト部位が周回後ニップ部に戻ってきたときのベルト裏面５２の温度及びベルト表面５１の温度を予測可能になっている。コントローラ７６は温度センサ６５によって各発熱体群５６、５７、５８、５９、６０、６１、６２直下のヒータ６４の温度異常を検知可能になっている。 Further, the fixing device 50 of FIG. 1 is provided with temperature sensors 65, 66, 67 for the heating element groups 56, 57, 58, 59, 60, 61, 62 in the main scanning direction, respectively. By the temperature sensors 66, 67, the controller 76 uses the temperature of the belt back surface 52 and the belt surface when the belt portion directly under each heating element group 56, 57, 58, 59, 60, 61, 62 returns to the nip portion after lap. The temperature of 51 can be predicted. The controller 76 can detect the temperature abnormality of the heater 64 directly under each heating element group 56, 57, 58, 59, 60, 61, 62 by the temperature sensor 65.

また、コントローラ７６は時間温度特性情報をベルト材質毎に予め記憶してもよい。ベルト５３は、ベルト表面温度がニップ位置の通過後、一旦下がりその下がった温度から目標温度に向かって上昇するという推移曲線を持ちベルト材質に応じた時間温度特性を有する。メモリ８２はこの時間温度特性を表す時間温度特性情報をベルト材質毎に予め記憶している。温度センサ６７は、ベルト５３のニップ位置からの周回開始後、ニップ位置から下流側に所定時間経過した後の周位置に設けられている。コントローラ７６は、これらの時間温度特性情報および検出温度により、ベルト材質によりベルト表面温度の最大値を予測してベルト表面温度を制御してもよい。 Further, the controller 76 may store the time-temperature characteristic information for each belt material in advance. The belt 53 has a transition curve in which the belt surface temperature drops once after passing through the nip position and then rises from the lowered temperature toward the target temperature, and has a time temperature characteristic according to the belt material. The memory 82 stores the time-temperature characteristic information representing the time-temperature characteristics in advance for each belt material. The temperature sensor 67 is provided at the circumferential position after a predetermined time has elapsed from the nip position to the downstream side after the start of the orbit from the nip position of the belt 53. The controller 76 may control the belt surface temperature by predicting the maximum value of the belt surface temperature depending on the belt material based on the time temperature characteristic information and the detected temperature.

また、定着装置５０は、図２（ｃ）の発熱体群５６、５７、５８、５９、６０、６１、６２の７群分の各加熱領域のうちの幅方向の中央領域（第１の発熱体群５９）において温度センサ６５が基板５４の裏面の温度を常時測定している。つまり中央領域の温度センサ６５は、発熱体群５６、５７、５８、５９、６０、６１、６２のうち、幅方向の中央領域に位置する第１の発熱体群５９に対応して設けられている。この中央の第１の発熱体群５９は常時加熱されるため、搬送される用紙のサイズの種別によらず、温度の過昇温あるいは温度不足を検出可能になっている。 Further, the fixing device 50 is a central region in the width direction (first heat generation) of the seven heating regions of the heating element groups 56, 57, 58, 59, 60, 61 and 62 in FIG. 2 (c). In the body group 59), the temperature sensor 65 constantly measures the temperature of the back surface of the substrate 54. That is, the temperature sensor 65 in the central region is provided corresponding to the first heating element group 59 located in the central region in the width direction among the heating element groups 56, 57, 58, 59, 60, 61, 62. There is. Since the first heating element group 59 in the center is constantly heated, it is possible to detect an excessive temperature rise or a temperature shortage regardless of the type of paper size to be conveyed.

また、図２（ｃ）のようにヒータ６４が７群分の各加熱領域のうち幅方向中央領域（第１の発熱体群５９）およびこの中央領域について互いに幅方向で対称に設けられた一対の加熱領域（第２の発熱体群５８、６０）を駆動する場合、一対の第２の発熱体群５８、６０のうちの一方に設けられた温度センサ６５、６６、６７の検知出力を使って制御を簡略化してもよい。 Further, as shown in FIG. 2C, a pair of heaters 64 are provided symmetrically in the width direction with respect to the central region in the width direction (first heating element group 59) and the central region among the heating regions of the seven groups. When driving the heating region (second heating element groups 58, 60), the detection outputs of the temperature sensors 65, 66, 67 provided in one of the pair of second heating element groups 58, 60 are used. The control may be simplified.

また、図２（ｃ）のようにヒータ６４は、基板５４の長手方向の両端部分の温度をそれぞれ測定する別の温度センサ７７、７８を設けてもよい。印字範囲をはみ出るサイズの用紙あるいは印字範囲の寸法にぴったり収まらない用紙が定着装置５０に搬送された際のベルト５３の端部の異常が検出可能になっている。 Further, as shown in FIG. 2C, the heater 64 may be provided with separate temperature sensors 77 and 78 for measuring the temperatures of both ends of the substrate 54 in the longitudinal direction, respectively. It is possible to detect an abnormality at the end of the belt 53 when a paper having a size that exceeds the print range or a paper that does not fit exactly in the size of the print range is conveyed to the fixing device 50.

図３は本実施形態に係る画像形成装置の構成例を示す図である。既述の符号はそれらと同じ要素を表す。実施形態に係る画像形成装置はＭＦＰ（Multi-Function Peripherals）１０であり、イエロー（Ｙ）用の感光体ドラム２２Ｙ、マゼンタ（Ｍ）用の感光体ドラム２２Ｍ、シアン（Ｃ）用の感光体ドラム２２Ｃ及びブラック（Ｋ）用の感光体ドラム２２Ｋと、感光体ドラム２２Ｙ、２２Ｍ、２２Ｃ、２２Ｋ上に潜像を形成する色毎の潜像形成部２８とを備えている。各色の潜像形成部２８はそれぞれ帯電器２３と、露光器１９とを備える。更にＭＦＰ１０は、色毎の潜像の現像器２４と、各現像器２４により可視化されたトナー像を用紙に転写する一次転写器２７（転写器）と、二次転写器２６と、定着装置５０とを備える。この定着装置５０は各一次転写器２７により転写出力された用紙７９（図１）のトナー像８０側のベルト表面５１およびベルト裏面５２を有する上記ベルト５３と、上記ヒータ６４と、上記温度センサ６５、６６、６７とを備えている。ベルト幅方向が各潜像形成部２８の主走査方向になるように、定着装置５０はＭＦＰ１０に設けられる。 FIG. 3 is a diagram showing a configuration example of the image forming apparatus according to the present embodiment. The above-mentioned symbols represent the same elements as those. The image forming apparatus according to the embodiment is an MFP (Multi-Function Peripherals) 10, a photoconductor drum 22Y for yellow (Y), a photoconductor drum 22M for magenta (M), and a photoconductor drum for cyan (C). It includes a photoconductor drum 22K for 22C and black (K), and a latent image forming unit 28 for each color that forms a latent image on the photoconductor drums 22Y, 22M, 22C, and 22K. The latent image forming unit 28 of each color includes a charger 23 and an exposure device 19, respectively. Further, the MFP 10 includes a latent image developer 24 for each color, a primary transfer device 27 (transfer device) that transfers the toner image visualized by each developer 24 to paper, a secondary transfer device 26, and a fixing device 50. And. The fixing device 50 includes the belt 53 having the belt front surface 51 and the belt back surface 52 on the toner image 80 side of the paper 79 (FIG. 1) transferred and output by each primary transfer device 27, the heater 64, and the temperature sensor 65. , 66, 67 and so on. The fixing device 50 is provided in the MFP 10 so that the belt width direction is the main scanning direction of each latent image forming unit 28.

図３においてＭＦＰ１０は本体１１の上部にオペレーションパネル１４を有し、本体１１内の中央部にプリンタ部１７を有し、本体１１の下部に、給紙カセット１８を備えている。プリンタ部１７は、イエロー（Ｙ）、マゼンタ（Ｍ）、シアン（Ｃ）、ブラック（Ｋ）の各色の画像形成部２０Ｙ，２０Ｍ，２０Ｃ，２０Ｋを含む。画像形成部２０Ｙは、感光体ドラム２２Ｙ、帯電器２３、現像器２４、一次転写器２７から構成されており、感光体ドラム２２Ｙの感光面上には、露光器１９からＬＥＤ光又はレーザ光が照射され、この感光体ドラム２２Ｙ上に静電潜像が形成される。帯電器２３は、感光体ドラム２２Ｙの表面を一様に帯電する。現像器２４はイエロートナーおよびキャリアを含む二成分現像剤を感光体ドラム２２Ｙに供給し、静電潜像を現像する。画像形成部２０Ｍ，２０Ｃ，２０Ｋの構成は画像形成部２０Ｙの構成と実質同じである。 In FIG. 3, the MFP 10 has an operation panel 14 at the top of the main body 11, a printer unit 17 at the center of the main body 11, and a paper cassette 18 at the bottom of the main body 11. The printer unit 17 includes image forming units 20Y, 20M, 20C, and 20K of each color of yellow (Y), magenta (M), cyan (C), and black (K). The image forming unit 20Y is composed of a photoconductor drum 22Y, a charger 23, a developer 24, and a primary transfer device 27, and LED light or laser light from the exposure device 19 is emitted from the exposure device 19 on the photosensitive surface of the photoconductor drum 22Y. When irradiated, an electrostatic latent image is formed on the photoconductor drum 22Y. The charger 23 uniformly charges the surface of the photoconductor drum 22Y. The developer 24 supplies a two-component developer containing yellow toner and a carrier to the photoconductor drum 22Y to develop an electrostatic latent image. The configuration of the image forming units 20M, 20C, and 20K is substantially the same as the configuration of the image forming unit 20Y.

ＭＦＰ１０は、駆動ローラ３１および従動ローラ３２に張架された中間転写ベルト２１を有し、二次転写器２６により中間転写ベルト２１上のトナー像を用紙Ｐに二次転写する。二次転写器２６は、駆動ローラ３１と、この駆動ローラ３１に対向する二次転写ローラ３３を有する。ＭＦＰ１０は二次転写ローラ３３から見て用紙搬送方向下流側に定着装置５０を有する。ＭＦＰ１０はメインコントローラ３６を有する。メインコントローラ３６は、画像形成部２０Ｙ，２０Ｍ，２０Ｃ，２０Ｋ及び定着装置５０の制御プログラム及び各種の制御データを記憶する。制御プログラムの具体例は、例えば給紙カセット１８内の用紙の紙質、用紙サイズ、環境温度に対応する定着装置５０の目標温度等である。制御データの具体例は、用紙サイズ毎の主走査方向の印字範囲の寸法と、選択的に加熱駆動する７つの発熱体群５６、５７、５８、５９、６０、６１、６２との対応関係等である。 The MFP 10 has an intermediate transfer belt 21 stretched on the drive roller 31 and the driven roller 32, and the toner image on the intermediate transfer belt 21 is secondarily transferred to the paper P by the secondary transfer device 26. The secondary transfer device 26 has a drive roller 31 and a secondary transfer roller 33 facing the drive roller 31. The MFP 10 has a fixing device 50 on the downstream side in the paper transport direction when viewed from the secondary transfer roller 33. The MFP 10 has a main controller 36. The main controller 36 stores the control programs of the image forming units 20Y, 20M, 20C, 20K, the fixing device 50, and various control data. Specific examples of the control program include, for example, the paper quality of the paper in the paper feed cassette 18, the paper size, the target temperature of the fixing device 50 corresponding to the ambient temperature, and the like. Specific examples of control data include the correspondence between the dimensions of the print range in the main scanning direction for each paper size and the seven heating element groups 56, 57, 58, 59, 60, 61, 62 that are selectively heated and driven. Is.

次に上述の構成の定着装置５０による温度測定動作について説明する。 Next, the temperature measurement operation by the fixing device 50 having the above configuration will be described.

ＭＦＰ１０にはオペレーションパネル１４から、用紙サイズ情報が入力される。ＭＦＰ１０は帯電および露光により静電潜像を感光体ドラム２２Ｙ、２２Ｍ、２２Ｃ、２２Ｋ上に形成する。ＭＦＰ１０は静電潜像を各色のトナーにより現像し、４色のトナー像を中間転写ベルト２１に転写する。ＭＦＰ１０はＡ４サイズの短辺が用紙搬送方向に平行に給紙カセット１８から引っ張り上げて、この用紙上にトナー像を二次転写する。ＭＦＰ１０は定着装置５０にタイミング信号を送り、定着装置５０はウォーミングアップを開始する。 Paper size information is input to the MFP 10 from the operation panel 14. The MFP 10 forms an electrostatic latent image on the photoconductor drums 22Y, 22M, 22C, and 22K by charging and exposure. The MFP 10 develops an electrostatic latent image with toners of each color and transfers the toner images of four colors to the intermediate transfer belt 21. The MFP 10 pulls up the A4 size short side from the paper cassette 18 in parallel with the paper transport direction, and secondarily transfers the toner image onto the paper. The MFP 10 sends a timing signal to the fixing device 50, and the fixing device 50 starts warming up.

定着装置５０のヒータ６４はスイッチングドライバＩＣ６３によって例えばＡ４長辺というサイズ情報により図２（ｃ）のように７つの発熱体群５６、５７、５８、５９、６０、６１、６２の全てを選択して発熱駆動する。印字範囲の発熱体群５６、５７、５８、５９、６０、６１、６２が発熱する。ハガキサイズの短辺幅というサイズ情報が入力された場合、スイッチングドライバＩＣ６３は基板長手方向中央部の第１の発熱体群５９を発熱させる。あるいはハガキよりも大きいサイズ情報の用紙が搬送された場合、定着装置５０は第１の発熱体群５９と、この第１の発熱体群５９の外側の第２の発熱体群５８、６０とを発熱させる。その次に大きいサイズ情報に対しては、同様にヒータ６４は第１の発熱体群５９、第２の発熱体群５８、６０及び第３の発熱体群５７、６１を発熱させる。 The heater 64 of the fixing device 50 selects all of the seven heating element groups 56, 57, 58, 59, 60, 61, 62 as shown in FIG. 2C by the switching driver IC63, for example, based on the size information of the long side of A4. It is driven by heat generation. The heating element groups 56, 57, 58, 59, 60, 61, 62 in the print range generate heat. When the size information of the short side width of the postcard size is input, the switching driver IC 63 heats the first heating element group 59 in the central portion in the longitudinal direction of the substrate. Alternatively, when a paper having a size information larger than that of the postcard is transported, the fixing device 50 connects the first heating element group 59 and the second heating element groups 58 and 60 outside the first heating element group 59. Make it heat. For the next largest size information, the heater 64 similarly heats the first heating element group 59, the second heating element groups 58, 60 and the third heating element groups 57, 61.

図４はベルト表面温度、ベルト裏面温度を含む時間温度特性を示す線図である。同図のグラフは本発明者がシミュレーションによって取得した値を表示している。図５、図６に図４と同じ内容を拡大して示す。図４には、７つの加熱領域のうちの何れか一箇所において、ヒータ裏面、ヒータ表面、ベルト裏面、ベルト表面、トナー上面（ベルト側）、トナー下面（紙側）及び加圧ローラ表面のそれぞれの時間温度特性が示されている。ニップ部分になると、ベルト裏面温度は１８４℃になり、ベルト表面温度は一時的に１７０℃程度まで低下する。ベルト裏面温度は、ニップ部を過ぎると、すぐに１９０℃程度まで上昇する。ベルト表面温度は、一旦はニップ部において１４０℃台まで低下するが、ベルト裏面がヒータ６４と接触しているので、ベルト裏面温度はヒータ表面温度と同じような履歴を持つ。トナー上面は１４０℃程度まで上昇し、トナー下面は９０℃程度にしかならない。これはトナー層により熱が伝わりにくいからである。 FIG. 4 is a diagram showing the time temperature characteristics including the belt surface temperature and the belt back surface temperature. The graph in the figure shows the values acquired by the present inventor by simulation. 5 and 6 show the same contents as those in FIG. 4 in an enlarged manner. In FIG. 4, in any one of the seven heating regions, the back surface of the heater, the front surface of the heater, the back surface of the belt, the surface of the belt, the upper surface of the toner (belt side), the lower surface of the toner (paper side), and the surface of the pressure roller are shown. The time-temperature characteristics of are shown. At the nip portion, the belt back surface temperature becomes 184 ° C., and the belt surface temperature temporarily drops to about 170 ° C. The temperature on the back surface of the belt rises to about 190 ° C immediately after passing the nip portion. The belt surface temperature once drops to the 140 ° C level at the nip portion, but since the belt back surface is in contact with the heater 64, the belt back surface temperature has a history similar to that of the heater surface temperature. The upper surface of the toner rises to about 140 ° C., and the lower surface of the toner is only about 90 ° C. This is because heat is less likely to be transferred by the toner layer.

ここで横軸の経過時間（秒）は、ニップ部よりも周回方向上流のニップ部手前位置を開始時点として、ニップ部を通過し、さらにニップ部よりも周回方向下流を一周して元のニップ部に戻るまでの時間範囲を表す。縦軸の温度は、ニップ部手前の開始位置においてほぼ一定の目標温度である目標温度を保っており、ニップ部に突入後、ニップ部で加熱及び熱交換によって温度が変動し、ニップ部を通過しさらにニップ部から離れて一周して元のニップ部に戻るまでの温度変化を表す。また、ヒータ６４は熱容量が大きいため、ヒータ裏面の温度変化はほとんど無い。 Here, the elapsed time (seconds) on the horizontal axis starts from the position in front of the nip portion upstream of the nip portion, passes through the nip portion, and further circles downstream of the nip portion in the circumferential direction to form the original nip. Represents the time range until returning to the part. The temperature on the vertical axis maintains the target temperature, which is an almost constant target temperature at the start position in front of the nip, and after entering the nip, the temperature fluctuates due to heating and heat exchange at the nip and passes through the nip. Furthermore, it represents the temperature change until it goes around the nip part and returns to the original nip part. Further, since the heater 64 has a large heat capacity, there is almost no temperature change on the back surface of the heater.

ベルト５３がニップ部位置から下流方向へ周回する最中、ベルト表面温度とベルト裏面温度とは同図の縦線で表される時点において均衡する。この均衡する時点はベルト部位がニップ部を離れてから、半周に到達する前の周位置であることを本発明者らは鋭意シミュレーションや実験によって見出した。この均衡する時点に対応する周位置に温度センサ６６、６７を設置して温度をモニタすることによって、そのベルト部位が一周して再度ニップ部の上流位置に戻ってきたときに目標温度に達するかどうかを予測することが可能となった。温度センサ６６、６７を、各加熱領域に設けることよって、温度センサ６６、６７が実測した温度と、図４の温度変化の度合い（プロポーション）とから、各加熱領域のベルト表面温度がニップ部に突入する前に目標温度になっているかどうかを確認できる。 While the belt 53 orbits in the downstream direction from the position of the nip portion, the belt front surface temperature and the belt back surface temperature are in equilibrium at the time represented by the vertical line in the figure. The present inventors have found through diligent simulations and experiments that the time of this equilibrium is the circumferential position after the belt portion leaves the nip portion and before reaching the half circumference. By installing temperature sensors 66 and 67 at the circumferential position corresponding to this equilibrium point and monitoring the temperature, does the target temperature reach the target temperature when the belt portion goes around and returns to the upstream position of the nip portion again? It became possible to predict whether or not. By providing the temperature sensors 66 and 67 in each heating region, the belt surface temperature of each heating region is set in the nip portion based on the temperature actually measured by the temperature sensors 66 and 67 and the degree of temperature change (proportion) in FIG. You can check if the target temperature is reached before rushing.

また、第２の発熱体群５８、６０のように左右対称の加熱領域を駆動する場合、左右何れか一方の加熱領域に設けられた温度センサ６６、６７の測定結果を取得することで足り、７つの加熱領域の全てに温度センサ６６、６７を設ける必要がなくなる。 Further, when driving symmetrical heating regions as in the second heating element groups 58 and 60, it is sufficient to acquire the measurement results of the temperature sensors 66 and 67 provided in either the left or right heating region. It is not necessary to provide temperature sensors 66 and 67 in all seven heating regions.

また、定着装置５０の熱容量を計算上又はシミュレーションによって取得することで、図４の温度変化を記憶したときの温度センサ６６、６７の測定結果が高温である場合、ベルト５３は既に暖まっていることを把握できる。あるいはヒータ６４が加温を続けているにもかかわらず、測定結果が低温である場合、ベルト５３は冷めていることを把握できる。ベルト５３の発熱領域が分割された構成であっても、用紙の坪量や外気温によってベルト５３の温度が変動したことを検知できる。 Further, when the measurement results of the temperature sensors 66 and 67 when the temperature change in FIG. 4 is stored by acquiring the heat capacity of the fixing device 50 by calculation or simulation are high, the belt 53 is already warm. Can be grasped. Alternatively, if the measurement result is low even though the heater 64 continues to heat, it can be grasped that the belt 53 is cold. Even if the heat generating region of the belt 53 is divided, it is possible to detect that the temperature of the belt 53 fluctuates depending on the basis weight of the paper and the outside air temperature.

図５は図４の時間温度特性情報のうち一部を抜き出して示す線図である。ベルト裏面、ベルト表面、トナー上面（ベルト５３側）及びトナー下面（用紙側）のそれぞれの各温度推移を同図は示す（ヒータ６４の熱容量が大きいため、温度変化がほとんど無いヒータ裏面の温度変化を省略する）。図６は図４の時間温度特性情報のうち一部を抜き出して示す線図である。ヒータ表面、ヒータ裏面、ベルト表面及びベルト裏面のそれぞれの温度推移を同図は示す。 FIG. 5 is a diagram showing a part of the time temperature characteristic information of FIG. 4 extracted. The figure shows the temperature transitions of the back surface of the belt, the front surface of the belt, the upper surface of the toner (53 side of the belt), and the lower surface of the toner (paper side). Omit). FIG. 6 is a diagram showing a part of the time temperature characteristic information of FIG. 4 extracted. The figure shows the temperature transitions of the heater front surface, the heater back surface, the belt surface, and the belt back surface.

そしてコントローラ７６は、メモリ８２から、時間温度特性情報、ベルト５３の周回速度、周回径、温度センサ６５、６６の周位置、温度センサ６７の周位置（（図４〜図６の推移曲線上で最大となる周位置）を読出し、決められた周位置のベルト部位がニップ部の上流位置に戻ってきたときのベルト表面温度を予測する。 Then, the controller 76 provides time-temperature characteristic information, the orbital speed of the belt 53, the orbital diameter, the circumferential positions of the temperature sensors 65 and 66, and the circumferential position of the temperature sensor 67 from the memory 82 (on the transition curves of FIGS. 4 to 6). The maximum peripheral position) is read out, and the belt surface temperature when the belt part at the determined peripheral position returns to the upstream position of the nip portion is predicted.

また、コントローラ７６はベルト材質毎にベルト表面温度を予測する。この場合、メモリ８２から、ベルト材質に応じた時間温度特性情報を読出す。図７（ａ）〜図７（ｃ）はメモリ８２に記憶されたベルト材質に応じた時間温度特性を示す線図である。図７（ａ）はベルト５３の基層の材質が層厚７０μｍのポリイミドである条件（第１の条件）での時間温度特性である。図７（ｂ）はベルト５３の基層の材質が層厚７０μｍのニッケルである条件（第２の条件）での時間温度特性である。図７（ｃ）はベルト５３の基層の材質が層厚７０μｍのニッケル層とシリコーンゴム層（通常の熱伝導率の１００倍の熱伝導率を持つ）とからなる条件（第３の条件）での時間温度特性である。図７（ｂ）、図７（ｃ）中の曲線の凡例は図７（ａ）中のそれらと同じである。 Further, the controller 76 predicts the belt surface temperature for each belt material. In this case, the time-temperature characteristic information corresponding to the belt material is read from the memory 82. 7 (a) to 7 (c) are diagrams showing the time temperature characteristics according to the belt material stored in the memory 82. FIG. 7A shows the time-temperature characteristics under the condition that the material of the base layer of the belt 53 is polyimide having a layer thickness of 70 μm (first condition). FIG. 7B shows the time-temperature characteristics under the condition that the material of the base layer of the belt 53 is nickel having a layer thickness of 70 μm (second condition). FIG. 7C shows a condition (third condition) in which the material of the base layer of the belt 53 is a nickel layer having a layer thickness of 70 μm and a silicone rubber layer (having a thermal conductivity 100 times higher than the normal thermal conductivity). It is the time temperature characteristic of. The curve legends in FIGS. 7 (b) and 7 (c) are the same as those in FIG. 7 (a).

コントローラ７６は起動時に、ハードウェア設定又はソフトウェア設定の読込みによってメモリ８２からベルト材質に応じた時間温度特性を読む。図７の例では第１〜第３の条件の何れかをコントローラ７６は選択する。コントローラ７６は、ベルト材質により異なる時間温度特性情報と、温度センサ６５、６６、６７からの検出温度情報と、定着条件とにより、ベルト表面温度の最大値を予測する。コントローラ７６は予め保持する閾値をベルト表面温度の最大値が超えると、例えばヒータ６４の加熱動作の停止、ベルト５３の速度を下げる等定着装置５０及びＭＦＰ１０を制御する。ベルト５３の異常発熱やベルト５３の破壊を防止でき、無駄な加熱をなくすことができる。 At startup, the controller 76 reads the time-temperature characteristics according to the belt material from the memory 82 by reading the hardware setting or the software setting. In the example of FIG. 7, the controller 76 selects any of the first to third conditions. The controller 76 predicts the maximum value of the belt surface temperature based on the time temperature characteristic information that differs depending on the belt material, the detected temperature information from the temperature sensors 65, 66, and 67, and the fixing conditions. When the maximum value of the belt surface temperature exceeds the threshold value held in advance, the controller 76 controls the fixing device 50 and the MFP 10 such as stopping the heating operation of the heater 64 and reducing the speed of the belt 53. Abnormal heat generation of the belt 53 and destruction of the belt 53 can be prevented, and unnecessary heating can be eliminated.

図４〜図７を総括すると、ヒータ６４をベルト裏面５２に接触させ、ベルト表面５１上で用紙をニップする構成では、冷たい用紙がニップ部の通過によりベルト表面５１から熱が逃げる。一方、ベルト裏面５２からは用紙がニップ部を通過中もベルト５３に熱が供給され続けるため、ベルト裏面温度が１９０℃近くにまで上昇する。ベルト裏面温度が高温になった頃、トナー粒子が溶解し始め、ベルト表面５１側の熱が奪われる。目標温度に達していたベルト表面温度は１４５℃まで落ちる。用紙がニップ部を抜けた直後では、ベルト表面温度とベルト裏面温度との温度差が大きい。 To summarize FIGS. 4 to 7, in a configuration in which the heater 64 is brought into contact with the back surface 52 of the belt and the paper is niped on the belt surface 51, heat escapes from the belt surface 51 when the cold paper passes through the nip portion. On the other hand, since heat is continuously supplied from the back surface 52 of the belt to the belt 53 even while the paper passes through the nip portion, the temperature of the back surface of the belt rises to nearly 190 ° C. When the temperature on the back surface of the belt becomes high, the toner particles begin to melt and the heat on the front surface 51 side of the belt is taken away. The belt surface temperature, which had reached the target temperature, drops to 145 ° C. Immediately after the paper has passed through the nip portion, the temperature difference between the belt front surface temperature and the belt back surface temperature is large.

用紙がニップ部を抜けた後、用紙と加熱接触していたベルト部位はヒータ６４から離れる。このベルト部位は周回し、ベルト表面温度は１４５℃から徐々に上昇し、ベルト裏面温度は１８５℃から徐々に下降する。ベルト５３の加熱接触部分が半周ほど周回するまでの間に、ベルト表面温度とベルト裏面温度とは均衡し、元の設定温度に戻る。 After the paper has passed through the nip portion, the belt portion that has been in thermal contact with the paper is separated from the heater 64. This belt portion orbits, the belt surface temperature gradually rises from 145 ° C, and the belt back surface temperature gradually falls from 185 ° C. The belt surface temperature and the belt back surface temperature are in equilibrium and return to the original set temperature until the heating contact portion of the belt 53 orbits about half a turn.

ベルト表面５１にはトナー及び用紙が接触するため、このベルト表面５１に直接温度センサ６６、６７を設置することができない。温度センサ６６、６７をベルト表面５１に設置することはベルト表面５１が傷ついてしまうからである。複数の加熱領域間で共通する同じ位置に温度センサ６６、６７を設置することは物理的な制約によりできないが、定着装置５０によれば、これらの加熱領域毎にベルト表面温度を把握することができる。 Since toner and paper come into contact with the belt surface 51, the temperature sensors 66 and 67 cannot be installed directly on the belt surface 51. If the temperature sensors 66 and 67 are installed on the belt surface 51, the belt surface 51 will be damaged. It is not possible to install the temperature sensors 66 and 67 at the same position common to a plurality of heating regions due to physical restrictions, but according to the fixing device 50, it is possible to grasp the belt surface temperature for each of these heating regions. can.

このように、本実施形態に係る定着装置および画像形成装置によれば、発熱体群５６〜６２毎に選択加熱する構成を有する定着システムにおいて、ベルト５３の幅方向の全ての加熱領域で発熱体群５６〜６２毎にベルト表面温度を監視することが可能となる。定着装置５０が消費する熱エネルギーを削減できる。印字範囲への集中的な加熱が可能となり、定着品質を高めることもできる。 As described above, according to the fixing device and the image forming device according to the present embodiment, in the fixing system having the configuration of selectively heating each heating element group 56 to 62, the heating element is generated in all the heating regions in the width direction of the belt 53. It is possible to monitor the belt surface temperature for each group 56-62. The heat energy consumed by the fixing device 50 can be reduced. Concentrated heating to the print range is possible, and fixing quality can be improved.

なお図１、図２において、７つの温度センサ６５、７つの温度センサ６６、７つの温度センサ６７は、発熱体群５６、５７、５８、５９、６０、６１、６２に対応した箇所にそれぞれ設けられていたが、温度センサ６５、６６、６７は何れも、基板５４の裏面側に発熱体群５６、５７、５８、５９、６０、６１、６２のうち何れか１つに対応した箇所に設けられていればよい。定着装置５０は、基板５４の裏面側に中央の第１の発熱体群５９の対応箇所に一つの温度センサ６５と、この第１の発熱体群５９の対応箇所に一つの温度センサ６７と、その反対側のベルト裏面５２に発熱体群５９の対応箇所に一つの温度センサ６６とを設け、これらの温度センサ６５、６６、６７が第１の発熱体群５９に対応した箇所の温度をそれぞれ測定することで上記実施形態の効果を得られる。また温度センサ６５、６６、６７の基板長手方向の位置は、第２の発熱体群５８、第２の発熱体群６０、第３の発熱体群５７、第３の発熱体群６１、第４の発熱体群５６及び第４の発熱体群６２のうち何れか一つに対応した箇所でもよい。 In FIGS. 1 and 2, the seven temperature sensors 65, the seven temperature sensors 66, and the seven temperature sensors 67 are provided at locations corresponding to the heating element groups 56, 57, 58, 59, 60, 61, and 62, respectively. However, the temperature sensors 65, 66, and 67 are all provided on the back surface side of the substrate 54 at a location corresponding to any one of the heating element groups 56, 57, 58, 59, 60, 61, 62. It suffices if it is done. The fixing device 50 includes a temperature sensor 65 at a corresponding portion of the first heating element group 59 in the center on the back surface side of the substrate 54, and one temperature sensor 67 at a corresponding portion of the first heating element group 59. One temperature sensor 66 is provided on the back surface 52 of the belt on the opposite side at the corresponding portion of the heating element group 59, and the temperatures of these temperature sensors 65, 66, 67 correspond to the first heating element group 59, respectively. By measuring, the effect of the above embodiment can be obtained. The positions of the temperature sensors 65, 66, 67 in the longitudinal direction of the substrate are the second heating element group 58, the second heating element group 60, the third heating element group 57, the third heating element group 61, and the fourth. It may be a place corresponding to any one of the heating element group 56 and the fourth heating element group 62.

なお図２の７つの発熱体群と用紙サイズとの関係は種々変更可能であり、発熱体群の分割数とそれぞれの幅は上記説明での例に限定はされるものではない。ＭＦＰ１０が５つの媒体サイズに対応していた場合には、発熱体群を５分割してもよい。各発熱体群の幅を拡大又は縮小することがある。発熱体群５６、５７、５８、５９、６０、６１、６２の全てを保護層によって覆ってもよい。上記説明では、ニップ位置はベルト周回方向Ｓにとったベルト５３の範囲と定義したが、ニップ位置をベルト５３の周位置の一点と定義してもよい。これらの変更をして実施したに過ぎない実施品に対して実施形態に係る定着装置の優位性は何ら損なわれるものではない。 The relationship between the seven heating element groups in FIG. 2 and the paper size can be changed in various ways, and the number of divisions of the heating element group and the width of each are not limited to the examples in the above description. If the MFP 10 corresponds to five medium sizes, the heating element group may be divided into five. The width of each heating element group may be increased or decreased. All of the heating element groups 56, 57, 58, 59, 60, 61, 62 may be covered with a protective layer. In the above description, the nip position is defined as the range of the belt 53 taken in the belt circumferential direction S, but the nip position may be defined as one point of the peripheral position of the belt 53. The superiority of the fixing device according to the embodiment is not impaired over the product in which these changes are merely implemented.

いくつかの実施形態を説明したが、これらの実施形態は、例として提示したものであり、発明の範囲を限定することは意図していない。これら実施形態は、その他の様々な形態で実施されることが可能であり、発明の要旨を逸脱しない範囲で、種々の省略、置き換え、変更を行うことができる。これら実施形態やその変形は、発明の範囲や要旨に含まれると同様に、特許請求の範囲に記載された発明とその均等の範囲に含まれるものである。 Although some embodiments have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the gist of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, as well as in the scope of the invention described in the claims and the equivalent scope thereof.

１０…ＭＦＰ（画像形成装置）、５０…定着装置、５１…ベルト表面、５２…ベルト裏面、５３…ベルト、５４…基板、５５…発熱体、５６〜６２…発熱体群、６３…スイッチングドライバＩＣ（駆動部）、６４…ヒータ、６５、６６、６７…温度センサ、８２…メモリ。 10 ... MFP (image forming device), 50 ... Fixing device, 51 ... Belt front surface, 52 ... Belt back surface, 53 ... Belt, 54 ... Substrate, 55 ... Heating element, 56-62 ... Heating element group, 63 ... Switching driver IC (Drive unit), 64 ... heater, 65, 66, 67 ... temperature sensor, 82 ... memory.

Claims

Photoreceptor drum and
A latent image forming portion that forms a latent image on the photoconductor drum,
A developer that develops and visualizes the latent image,
A transfer device that transfers the toner image visualized by this developer to paper, and
An endless belt having a belt surface and back surface of the belt, the substrate is located in a width the belt back side parallel to the direction of this belt, the heating element abuts the belt back surface provided on the substrate, and the heating element a heater having a drive unit for driving, and the before and Symbol heating belt than abut nip position provided in any of the belt back surface of the belt table surface contact and the opposite side of the rotating direction downstream of said belt A fixing device including a temperature sensor and a fixing device for fixing the toner image on the paper.
A memory in which time-temperature characteristic information representing the time-temperature characteristics of the belt surface temperature of the belt provided in the fixing device is stored in advance, and
The detected temperature is collected from the temperature sensor, and from the orbiting speed of the belt, the orbital diameter of the belt, the orbital position of the temperature sensor, and the time temperature characteristic information, any part of the belt goes around from the nip position. A controller that predicts the belt surface temperature when returning to the upstream position of the nip position, and
With
The time-temperature characteristic is lowered, after the passage of the belt surface temperature is the nip position of the belt rises from once down the lowered temperature, after the belt back surface temperature passes the nipping position, once raised from the raised temperature is represented by a transition curve that,
The temperature sensor is provided at a peripheral position where the belt surface temperature becomes maximum on the transition curve.
Image forming device.

Photoreceptor drum and
A latent image forming portion that forms a latent image on the photoconductor drum,
A developer that develops and visualizes the latent image,
A transfer device that transfers the toner image visualized by this developer to paper, and
An endless belt having a belt surface and back surface of the belt, the substrate is located in a width the belt back side parallel to the direction of this belt, the heating element abuts the belt back surface provided on the substrate, and the heating element a heater having a drive unit for driving, and the before and Symbol heating belt than abut nip position provided in any of the belt back surface of the belt table surface contact and the opposite side of the rotating direction downstream of said belt A fixing device including a temperature sensor and a fixing device for fixing the toner image on the paper.
A memory in which time-temperature characteristic information representing the time-temperature characteristics of the belt surface temperature of the belt provided in the fixing device is stored in advance for each material of the belt, and
A controller that collects the detected temperature from the temperature sensor, predicts the maximum value of the belt surface temperature according to the material of the belt based on the time temperature characteristic information and the detected temperature, and controls the belt surface temperature.
With
The time-temperature characteristic is lowered, after the passage of the belt surface temperature is the nip position of the belt rises from once down the lowered temperature, after the belt back surface temperature passes the nipping position, once raised from the raised temperature is represented by a transition curve that,
In the temperature sensor, the belt surface temperature reaches the maximum on the transition curve at the circumferential position after a predetermined time elapses downstream from the nip position after the start of the orbit from the nip position on which the belt serves as a reference. It is provided at the peripheral position,
Image forming device.

Photoreceptor drum and
A latent image forming portion that forms a latent image on the photoconductor drum,
A developer that develops and visualizes the latent image,
A transfer device that transfers the toner image visualized by this developer to paper, and
An endless belt having a belt surface and back surface of the belt, the substrate is located in a width the belt back side parallel to the direction of this belt, the heating element abuts the belt back surface provided on the substrate, and the heating element a heater having a drive unit for driving, and the before and Symbol heating belt than abut nip position provided in any of the belt back surface of the belt table surface contact and the opposite side of the rotating direction downstream of said belt A fixing device including a temperature sensor and a fixing device for fixing the toner image on the paper.
A memory in which time-temperature characteristic information representing the time-temperature characteristics of the belt surface temperature of the belt provided in the fixing device is stored in advance, and
The detected temperature is collected from the temperature sensor, and from the orbiting speed of the belt, the orbital diameter of the belt, the orbital position of the temperature sensor, and the time temperature characteristic information, any part of the belt goes around from the nip position. A controller that predicts the belt surface temperature when returning to the upstream position of the nip position, and
With
The time-temperature characteristic after passing the belt surface temperature of the belt of the nip position, expressed in deviation curve that once drops increases from the lowered temperature,
The temperature sensor is provided at a position where the belt surface temperature becomes maximum on this transition curve.
Image forming device.

Photoreceptor drum and
A latent image forming portion that forms a latent image on the photoconductor drum,
A developer that develops and visualizes the latent image,
A transfer device that transfers the toner image visualized by this developer to paper, and
An endless belt having a belt surface and back surface of the belt, the substrate is located in a width the belt back side parallel to the direction of this belt, the heating element abuts the belt back surface provided on the substrate, and the heating element a heater having a drive unit for driving the a front Symbol heating element and the belt is provided on one of said belt back surface of the belt surface and the opposite side of the rotating direction downstream of the belt than in contact with the nip position A fixing device including a temperature sensor and fixing the toner image on the paper.
A memory in which time-temperature characteristic information representing the time-temperature characteristics of the belt surface temperature of the belt provided in the fixing device is stored in advance for each material of the belt, and
A controller that collects the detected temperature from the temperature sensor, predicts the maximum value of the belt surface temperature according to the material of the belt based on the time temperature characteristic information and the detected temperature, and controls the belt surface temperature.
With
The time-temperature characteristic after passing the belt surface temperature of the belt of the nip position, expressed in deviation curve that once drops increases from the lowered temperature,
In the temperature sensor, the belt surface temperature reaches the maximum on this transition curve at the circumferential position after a predetermined time elapses downstream from the nip position after the start of the orbit from the nip position on which the belt serves as a reference. It is provided at the peripheral position,
Image forming device.

The heating element has a plurality of heating elements provided on the substrate in the width direction.
The image forming apparatus according to any one of claims 1 to 4, wherein the driving unit selectively drives a plurality of heating element groups each including a plurality of the heating elements.

The image forming apparatus according to claim 5 , wherein the temperature sensor is provided corresponding to the heating element group located in the central region in the width direction among the plurality of heating element groups.

When the heater drives a central region in the width direction and a pair of heating regions symmetrically provided in the width direction with respect to the central region in each heating region corresponding to the number of the heating element group, the pair of heating elements is generated. The image forming apparatus according to claim 5 or 6, wherein the output of the temperature sensor provided in one of the body groups is used.

The image forming apparatus according to any one of claims 5 to 7, further comprising another temperature sensor for measuring the temperature of both end portions in the longitudinal direction of the substrate.