JPH0517664U

JPH0517664U - Heat roller in fixing device

Info

Publication number: JPH0517664U
Application number: JP7381791U
Authority: JP
Inventors: 嘉男坂田
Original assignee: Kaneka Corp
Current assignee: Kaneka Corp
Priority date: 1991-08-20
Filing date: 1991-08-20
Publication date: 1993-03-05

Abstract

(57)【要約】【目的】構造が簡単でコスト的にも安価であり、しかも
設置スペースも極めて小さいか、若しくは新たな設置ス
ペースを全く必要としない過剰昇温防止手段を組み込ん
だヒートローラーを提供せんとするものである。【構成】給電ブラシ自体にバイメタル機能を付与するか
若しくは給電ブラシと電源との間であってヒートローラ
の表面温度を感知しうる位置にバイメタルより構成され
た電流遮断回路を設けたことを特徴とする。 (57) [Summary] [Purpose] A heat roller that has a simple structure and is inexpensive in cost, and has a very small installation space or a built-in excessive temperature rise prevention means that does not require any new installation space. It is intended to be provided. [Structure] A power supply brush itself is provided with a bimetal function, or a current cutoff circuit composed of bimetal is provided between the power supply brush and the power supply at a position where the surface temperature of the heat roller can be sensed. To do.

Description

【考案の詳細な説明】【０００１】【産業上の利用分野】本発明は、複写機、ファクシミリ、プリンタ等の電子写真方式の装置において、記録紙上に転写したトナー像を定着させる為に設けられた定着装置に用いるヒートローラーに関し、更に詳しくは温度制御を簡単な構成で可能にしたヒートローラーに関する。【０００２】【従来の技術】複写機、ファクシミリ、プリンタ等の電子写真方式の装置においては、現像装置の感光ドラムから記録紙上に転写されたトナー像を、トナー粒子を記録紙の繊維にからますことによって記録紙に熱定着させる必要がある。定着装置は図８に示す如く、熱源を有するヒートローラーＡと、表面に耐熱性樹脂を被覆した押さえローラＢを対接して構成され、ヒートローラーＡと押さえローラーＢ間にトナー像を転写した記録紙Ｃを通過させることによってトナーの定着を行う。【０００３】ヒートローラーには、赤外線ランプやハロゲンランプ等の熱源を熱伝導良好な金属製スリーブの軸心位置に内装した間接加熱タイプが最も一般的であるが、この間接加熱タイプのものでは高価な細管状ランプが必要となるうえに金属製スリーブとしても厚肉で且つ表面を高精度に平滑加工したものが必要となることから全体が極めて高価となる問題があり、又、間接加熱である為に迅速な昇温ができない問題がある。このような問題点を解決するものとして、最近では間接加熱タイプに代わって直接加熱タイプのものが普及し出している。【０００４】直接加熱タイプの代表的なものとしては図９に示す如く、円筒状の絶縁体表面に導電性材料よりなる発熱層を塗布して発熱体ａを構成し、この発熱体両端部の外周面に帯片状の摺動片ｂを接触させて、回転する発熱体ａに対し摺動片ｂを通じて給電するものと、図10に示す如く、全体が導電性セラミックスから形成された円筒状の発熱体ａの両端部外周にベアリング等の軸受Ｐを外嵌し、該軸受Ｐにより発熱体ａを回転自在に支持するとともに、軸受Ｐを介して発熱体両端部に給電を行うものとがある。更に、図11として示すように本考案者が既に提案したところの、軸部ｃに径方向に弾性拡縮する導通端子Ｓを密嵌し、これに給電ブラシＲを介して給電するものとがある。【０００５】ところで、このようにして給電を受けるヒートローラにおいては、その表面温度の管理は極めて重要である。即ち、現像剤の良好な定着を保証する為にはヒートローラを所定温度に維持する必要があり、又、火災等の発生を防止する観点からも過剰な昇温は避けられるべきである。従来は、ヒートローラの過剰昇温を防止する手段としては、ヒートローラ表面に応答性のよい温度センサを近接配置し、この温度センサから出力される信号を別途設けた電気回路によって処理し、ヒートローラへの供給電力を制限したり、電力供給を遮断している。【０００６】【考案が解決しようとする課題】しかしながら、このような過剰昇温防止手段は、高価な温度センサを使用するうえに、該温度センサの出力信号を監視する為の電気回路を別途必要とすることから、高価であり、装置の全体コストを上昇させる要因となる。又、全体装置の小型化をはばむ要因ともなる。本考案はかかる現況に鑑みてなされたものであり、構造が簡単でコスト的にも安価であり、しかも設置スペースも極めて小さいか、若しくは新たな設置スペースを全く必要としない過剰昇温防止手段を開示し、この過剰昇温防止手段を組み込んだヒートローラーを提供せんとするものである。【０００７】【課題を解決するための手段】かかる課題を解決した第１考案は、発熱部と軸部が同一素材で一体成形され、当該成形体の中空とされた両端部に導通端子が密嵌されるとともに前記両導通端子の少なくとも一方が、導電性接触片を対向配置して構成され且つ少なくとも一方の導電性接触片をバイメタル機能を有するバネ弾性片となした給電ブラシによって挟持されて給電を受ける構成としたことを特徴としている。導通端子としては径方向に弾性拡縮するコイル状のものを用いることが好ましく、特に短い環状部材を、コイル状導通端子と給電ブラシとの間に介在させることが好ましい。【０００８】又、導通端子と成形体との接触を良好にするとともに軸部の昇温を抑制する為には、成形体の両端中空部内面の一部又は全部に柔らかい導電性金属を、蒸着、メッキ又はコーティング等の手段により被覆することが望まれる。【０００９】又、本考案は導通端子を介して給電する以外のものにも適用でき、例えば、第２考案は、ヒートローラの端部外周面に給電ブラシを摺設して給電を行うヒートローラにおいて、給電ブラシとしてバイメタル機能を有するバネ弾性片を用いたことを特徴としている。【００１０】上記したものは、給電ブラシの一部又は全部にバイメタルを用いることによって、給電ブラシに電流遮断機能を付与したものであるが、給電機能と電流遮断機能は独立させることも可能で、例えば第３考案は、バイメタル機能を有するバネ弾性片と対向接点よりなる遮断回路をヒートローラ表面の温度を感知しうる位置に配置するとともに、該遮断回路を前記ヒートローラに電力を供給する給電ブラシと電源との回路途中に介在させたことを特徴としている。【００１１】【作用】第１考案のヒートローラは、給電ブラシから導通端子を経由して両軸端部に電力を供給し、発熱部を加熱する。発熱部の表面温度は導通端子を介した熱伝導、あるいは空間伝播する輻射熱により給電ブラシに伝達される。給電ブラシはバイメタル機能を有するバネ弾性片から構成され、このバネ弾性片が導通端子を挟持している為、給電ブラシの温度が過剰に昇温したときにはこのバネ弾性片が変形して、導通端子への電力供給を即座に遮断する。そして、発熱部の表面温度が所定温度以下となったときには、バネ弾性片は元の形状に復帰して導通端子を挟持した状態となり、発熱部への給電を再開するものである。【００１２】給電ブラシから供給される電力を軸部へ伝達する導通端子としてコイル状導通端子を用いたときには、コイル状導通端子は径方向に弾性拡縮する為、セラミックス成形体の両端中空部に内嵌することは容易であり、且つ装着後はコイル状導通端子を中空部内壁に密着させることができる。又、コイル状導通端子を構成する各リング部分は個別に拡縮する為、軸端中空部内面が平滑でない場合でもコイル状導通端子と軸端中空部内面との接触は確実に行われ良好な通電状態が保証される。又、コイル状導通端子は一端が軸端中空部に内嵌されていても遊端側はコイル状導通端子が変形することによって比較的自由に移動できるので、組立て時にヒートローラー、導通端子及び給電ブラシを高精度に組合わせる必要がなくなり作業性が著しく向上する。【００１３】又、コイル状導通端子よりも短い環状部材をコイル状導通端子の遊端側に密接状態で外装した場合は、給電ブラシと導通端子を継ぐことが容易となるうえに、コイル状導通端子は環状部材内で回転することから、環状部材の内面形状のみがコイル状導通端子の回転に適していればよいから、給電ブラシの形状は比較的自由に設計することができる。【００１４】成形体の両端中空部内面の一部又は全部に柔らかい導電性金属を、蒸着、メッキ又はコーティング等の手段により被覆して低抵抗部を形成した場合は、成形体端部を通過する電流の大部分はこの低抵抗部を通過する為、軸部本体を通過する電流は極めて小さなものとなり、軸部外周及び内周からの発熱量は大幅に低下する。【００１５】第２考案においては、ヒートローラが過剰昇温したときには、この温度はヒートローラの端部外周面に摺設している給電ブラシによっても感知され、このとき給電ブラシはバイメタル機能によって変形して、ヒートローラへの給電を遮断する。【００１６】第３考案においては、ヒートローラが過剰昇温したときには、この温度は、ヒートローラに近接位置であって且つ給電ブラシと電源との回路途中に介在させられた電流遮断回路によって検知され、電流遮断回路は給電を遮断する。【００１７】【実施例】次に本考案の詳細を図示した実施例に基づき説明する。図１は本考案が適用されるヒートローラーの概要を示す説明図である。図中１は円筒状の発熱部であり、図中２は前記発熱部１の両端から突設した管状軸部である。図例の発熱部１は中空であるが中実とすることも可能である。発熱部１及び管状軸部２は導電性セラミックスを用いて一体成形されている。発熱部１及び管状軸部２の素材としては導電性セラミックス以外のもの、例えば金属を用いることも可能であるが、その電気抵抗の範囲は両軸端間において５Ω〜100 Ωに設定することが望まれる。これは５Ω以下であると発熱量が大きすぎて周辺部材の耐熱性に問題が生じるうえに導電性セラミックス自体の熱劣化が懸念される為であり、又、100 Ω以上であると発熱量が小さすぎてトナーの熱定着ができない為である。【００１８】ヒートローラーは軸受Ｐで回転自在に支持され、両端の軸部内面に装着した導通端子Ｓを介して給電ブラシＲにより給電を行っている。軸受Ｐとしてはベアリングは勿論のこと無機質摺動材を分散させた金属やポリイミド、ポリアミドイミド等の耐熱性樹脂を用いることも可能である。いずれを用いるかはヒートローラの温度や寿命等を考慮して適宜選択される。【００１９】第１考案は、前記構成のヒートローラにおいて、給電ブラシＲにバイメタルを利用した電流遮断機能を付与したことを特徴としている。バイメタルとは、熱膨張率の異なる二種の金属を張り合わせ、これを接点と組み合わせて、所定温度で開閉する接点を形成したものであり、極めて簡易な構造で、且つ確実な作動が期待できるものである。本考案はこのバイメタル機能を給電ブラシＲに付与したもので、例えば、図２（イ）（ロ）に示す如く、熱膨張率の異なる２種の金属m1， m2を張り合わせて構成したバネ弾性を有する導電性接触片３，３を、間に導通端子Ｓを挟持しうるようにして相対して配置した構造のものが採用される。導電性接触片３，３はヒートローラの表面温度が所定温度以上に昇温したときには、バネ弾性により図３に示すように外方へ向かって反り返り、その内面が導通端子Ｓから離れてヒートローラへの給電を遮断するものである。そして、ヒートローラの表面温度が所定温度以下となったときには、導電性接触片３，３は元の形状に復帰して導通端子Ｓを挟持した状態となり、ヒートローラへの給電を再開するものである。【００２０】上記実施例では、給電ブラシＲを構成する相対する導電性接触片が共にバイメタル機能を有するものであったが、バイメタル機能は片側だけに付与することも可能である。又、導電性接触片の一部にバイメタル機能を与えることもできる。又、給電ブラシＲの形状は他の形状とすることも可能で、例えば図４に示す如く相対する導電性接触片3a，3aを一体となした略Ｕ字形の物を用いることもできる。このような形状のものを採用したときには、給電ブラシＲを一本のビス４によって固定することが可能となり、給電ブラシＲの取付けが容易となる。【００２１】図２及び図３においては、導通端子Ｓとして金属板をロール状に曲成したものを用いている。これは、導通端子Ｓを径方向に弾性拡縮可能にすることで、軸端部内壁との接触を密にして導通を良好にするとともに、熱膨張した導通端子Ｓがあまり熱膨張しないセラミックス製の軸端部を破壊することを防止したものである。【００２２】導通端子Ｓとしては、径方向に弾性拡縮するものであれば他のものも採用され、例えば図５に示すようにコイル状導通端子５を用いることも可能である。コイル状導通端子５は一端が軸端中空部に内嵌されていても遊端側はコイル状導通端子５が変形することによって比較的自由に移動できるので、このようなコイル状導通端子を用いたときには、組立て時にヒートローラー、導通端子及び給電ブラシの高精度な位置合わせ作業が不要となり、作業性が著しく向上する。図中６はコイル状導通端子の端部に外嵌された環状部材であり、コイル状導通端子５の給電ブラシＲへのセッティングを容易にするとともに、セッテイング後はコイル状導通端子５を回転可能に抱持することによって、回転するコイル状導通端子５と給電ブラシＲとの電気的導通を保証している。【００２３】図中７は、軸端中空部内面にコイル状導通端子S1との接触を良好にし、且つ軸受等周辺部材への熱負荷を小さくする為に軸端部の高温化を避ける為に、軸端中空部内面に形成した蒸着、メッキ又はコーティング等の手段により導電性金属を配して構成した低抵抗部である。該低抵抗部７の厚みは極めて薄くその素材はアルミニウムや銅等の柔らかい金属が用いられる。低抵抗部７を設ける手段として蒸着、メッキ又はコーティング等を採用したのはこれら手段によれば成形体表面の起伏形状を埋めるようにして導電性金属を被覆できる為、成形体への良好な通電が可能となるからである。低抵抗部７の長さは図例のものでは軸部２長さにほぼ一致しているが、この長さは適宜設定される。低抵抗部７の長さは最大でも軸部長さ程度確保できれば充分であるから、蒸着等による導電性金属の被覆作業も極めて容易である。又、低抵抗部７は中空部内周面において全周にわたって形成することも可能であるが、一部に設けてもよい。中空部内周面に被覆された導電性金属には柔らかい素材が用いられていることから、導通端子と中空部内面との接触は極めて良好である。そして、このようなヒートローラーに対してコイル状導通端子S1を介して電圧が印加された場合は、コイル状導通端子との接触部から流入した電流の大部分は軸端部内周面に被覆された低抵抗部７を通過する為、軸部２本体内を通過する電流は極めて小さく、軸部内面及び外面における発熱量は著しく小さくすることができる。従って、軸受Ｐへの熱負荷は僅かとなり、耐熱性の低い軸受でも使用が可能となるので、従来使用することができなかった安価な軸受の使用が可能となる。【００２４】図６（イ),（ロ）は第２考案であり、ヒートローラへの給電をヒートローラ両端部外周に摺接する給電ブラシＲ’を介して行う場合に適用したものである。第２考案においては、図６（ロ）に示す如く、ヒートローラの端部外周に摺接する給電ブラシＲ’をバイメタルから構成している。第２考案においては、ヒートローラが過剰昇温したときには、ヒートローラに摺接する給電ブラシＲ’が反り返ってヒートローラへの給電を遮断するものである。【００２５】図７として示すものは第３考案である。上記した第１考案並びに第２考案が給電ブラシ自体にバイメタル機能を付与したものであったのに対し、第３考案はバイメタル機能を有するバネ弾性片８と対向接点９よりなる電流遮断回路10を給電ブラシＲ”とは別途作製し、該電流遮断回路10をヒートローラ表面の温度を感知しうる位置に配置するとともに、該電流遮断回路10を前記ヒートローラに電力を供給する給電ブラシＲ”と電源との回路途中に介在させたことを特徴としている。第３考案においてはヒートローラが過剰昇温すると電流遮断回路10を構成するバネ弾性片８が反り返って電流が遮断され、所定温度にまで降温すればバネ弾性片８が復帰して給電が再開される。【００２６】このように本考案のヒートローラは、給電ブラシ自体にバイメタル機能を付与したり、或いは給電ブラシと電源との間にバイメタル機能を有する電流遮断回路を介在させているので、ヒートローラが過剰昇温したときには、即座にバイメタルが作動してヒートローラへの給電を遮断することができる。そして、電流遮断の結果、所定温度以下にまで温度降下したときには、バイメタルが即座に復帰して給電が再開される。したがって、ヒートローラの表面温度を一定に維持でき、過剰昇温に起因するヒートローラーや周辺部品の劣化や火災の発生を防止することが可能となる。しかも本考案はバイメタルを利用したものであるから、構造が簡単で、小型化が可能であるうえに極めて安価でもあり、量産品への適応が容易である。【００２７】【考案の効果】本考案の定着装置におけるヒートローラーは、給電ブラシ自体にバイメタル機能を付与するか若しくは給電ブラシと電源との間にバイメタル機能を利用した電流遮断回路を設けた構成としたので、簡単且つ安価な構成でヒートローラを所定温度に維持することが可能となるとともに、過剰昇温に起因する周辺部品の劣化や火災の危険性を完全に防止することができる。特に第１考案及び第２考案は給電ブラシ自体にバイメタル機能を付与していることから、バイメタル機能を付与するに際して、設置空間を別途必要することもないのでヒートローラが大型化することもない。【００２８】又、給電ブラシから軸部に電力を供給する導通端子としてコイル状導通端子を用いたときには、導通端子と軸端中空部内面との良好な通電状態が保証できるうえに、組立て時にヒートローラー、導通端子及び給電ブラシを高精度に組合わせる必要もなくなり、作業性が著しく向上する。【００２９】又、コイル状導通端子よりも短い環状部材をコイル状導通端子の端部に外嵌した場合は、給電ブラシと導通端子を継ぐことが容易となるうえに、コイル状導通端子と給電ブラシとの導通も良好になる。【００３０】又、成形体の両端中空部内面の一部又は全部に柔らかい導電性金属を、蒸着、メッキ又はコーティング等の手段により被覆して低抵抗部を形成した場合は、成形体端部を通過する電流の大部分はこの低抵抗部を通過する為、軸部本体を通過する電流は極めて小さなものとなり、軸部外周及び内周からの発熱量を大幅に低下させることができ、軸受や周辺部品への負担を軽減することができる。[Detailed description of the device] [0001] [Industrial applications] The present invention is applied to an electrophotographic apparatus such as a copying machine, a facsimile, and a printer. , A fixing device provided for fixing the toner image transferred on the recording paper. For details on the heat roller, a heat roller that enables temperature control with a simple configuration. Regarding the ruler. [0002] [Prior Art] In electrophotographic devices such as copiers, facsimiles, printers, etc., The toner image transferred onto the recording paper from the photosensitive drum of It is necessary to heat-fix it on the recording paper due to the fact that it is damaged. The fixing device is shown in Fig. 8. As shown, a heat roller A having a heat source and a pressing roller whose surface is coated with a heat resistant resin Roller B is placed in contact with each other. The toner is fixed by passing the recording paper C onto which the image has been transferred. [0003] For the heat roller, use a heat source such as an infrared lamp or halogen lamp for good heat conduction. The indirect heating type, which is installed at the axial center of the metal sleeve, is the most common. Indirect heating type requires expensive thin tube lamps and metal Since it is necessary to have a thick wall with a highly accurate smooth surface, There is a problem that the whole becomes extremely expensive, and since it is indirect heating, it is possible to raise the temperature quickly. There is no problem. Recently, as a solution to these problems, indirect heating Direct heating type is becoming popular in place of Ip. [0004] As shown in Fig. 9, a typical direct heating type is a cylindrical insulator surface. A heating layer made of a conductive material is applied to the heating element a to form the heating element a. The strip-shaped sliding piece b is brought into contact with the outer peripheral surface, and the sliding piece b is passed through the rotating heating element a. Power supply, and as shown in Fig. 10, it is made entirely of conductive ceramics. A bearing P such as a bearing is externally fitted to the outer circumference of both ends of the cylindrical heating element a. The heating element a is supported more rotatably and is supplied to both ends of the heating element through the bearing P. There are things that do electricity. Further, as shown in FIG. 11, the shaft part c has a radial direction which has already been proposed by the present inventor. A conductive terminal S that elastically expands and contracts in the direction is tightly fitted, and power is supplied to this through a power supply brush R. There is [0005] By the way, the surface temperature of a heat roller that receives power in this way is Degree management is extremely important. That is, in order to ensure good fixing of the developer, heat It is necessary to keep the tracker at a predetermined temperature, and also to prevent the occurrence of fire. Also, excessive temperature rise should be avoided. Conventionally, it prevents excessive temperature rise of the heat roller. As a means to stop, place a temperature sensor with good response on the surface of the heat roller. , The signal output from this temperature sensor is processed by an electric circuit provided separately, The power supply to the controller is limited or the power supply is cut off. [0006] [Problems to be solved by the device] However, such an excessive temperature rise prevention means uses an expensive temperature sensor. In addition, a separate electric circuit for monitoring the output signal of the temperature sensor is required. Therefore, it is expensive and becomes a factor of increasing the overall cost of the device. In addition, It is also a factor that prevents miniaturization. The present invention was made in view of the current situation. Is the structure simple and cost-effective, and is the installation space extremely small? Or, disclose means for preventing excessive temperature rise that does not require any new installation space, It is intended to provide a heat roller incorporating this excessive temperature rise prevention means. . [0007] [Means for Solving the Problems] In the first invention that solves such a problem, the heat generating portion and the shaft portion are integrally formed of the same material, Conductive terminals are closely fitted to both hollowed end portions of the molded body, and the conductive ends are At least one of the children is configured with opposing conductive contacts and at least one One of the conductive contact pieces is a power supply brush in which a spring elastic piece having a bimetal function is used. It is characterized in that it is sandwiched and received power. It is preferable to use a coil-shaped conductive terminal that elastically expands and contracts in the radial direction. A particularly short annular member between the coil-shaped conducting terminal and the power feeding brush. And are preferred. [0008] Further, in order to improve the contact between the conductive terminal and the molded body and suppress the temperature rise of the shaft portion. In, a soft conductive metal is vapor-deposited on a part or all of the inner surface of the hollow part at both ends of the molded body, It is desired to coat by means such as plating or coating. [0009] The present invention can also be applied to anything other than supplying power through a conduction terminal, for example, 2 The idea is to heat the power supply by sliding a power supply brush on the outer peripheral surface of the end of the heat roller. In the roller, a spring elastic piece having a bimetal function was used as a power feeding brush. It is characterized by [0010] The above-mentioned ones can be made by using bimetal for a part or all of the power feeding brush. The current supply function is added to the power supply brush. The function can be independent, for example, the third invention is a spring having a bimetal function. A position where the temperature of the heat roller surface can be sensed by the cutoff circuit consisting of the elastic piece and the opposite contact And the cut-off circuit for supplying electric power to the heat roller. It is characterized by being interposed in the circuit between the power source and the power supply. [0011] [Action] In the heat roller of the first invention, the electric power is supplied from the power supply brush to the end portions of both shafts via the conduction terminals. Power is supplied to heat the exothermic part. The surface temperature of the heat generating part is heat conduction through the conduction terminal, Alternatively, the radiant heat that propagates in space is transmitted to the power feeding brush. Power supply brush is It is composed of a spring elastic piece that has a metal function, and this spring elastic piece clamps the conduction terminal. Therefore, when the temperature of the power supply brush rises excessively, this spring elastic piece is deformed. Then, the power supply to the conduction terminal is immediately cut off. And the surface temperature of the heat generating part is When the temperature falls below a certain temperature, the elastic piece returns to its original shape and clamps the conduction terminal. Then, the power supply to the heat generating portion is restarted. [0012] Coil-shaped conduction as a conduction terminal that transmits the power supplied from the power supply brush to the shaft When a terminal is used, the coiled conductive terminal expands and contracts in the radial direction, so It is easy to fit into the hollow parts at both ends of the molded product, and after mounting, The communication terminal can be brought into close contact with the inner wall of the hollow portion. It also constitutes a coil-shaped conducting terminal. Since each ring part that expands and contracts individually, even if the inner surface of the hollow part of the shaft end is not smooth, The contact between the ring-shaped conducting terminal and the inner surface of the hollow shaft end is ensured, and a good energization state is guaranteed. Be done. Even if one end of the coil-shaped conducting terminal is fitted inside the hollow shaft end, Deformation of the il-shaped conductive terminals allows them to move relatively freely. It is not necessary to combine the heat roller, conduction terminal and power supply brush with high precision. Workability is significantly improved. [0013] Also, attach an annular member shorter than the coil-shaped conducting terminal to the free end side of the coil-shaped conducting terminal. When it is packaged in the state, it is easy to connect the power supply brush and the conduction terminal, Since the coil-shaped conducting terminal rotates in the annular member, only the inner surface shape of the annular member is The shape of the power supply brush is relatively self-contained, as long as it is suitable for the rotation of the coil-shaped conductive terminal. It can be designed for any reason. [0014] A soft conductive metal is vapor-deposited or plated on part or all of the inner surface of the hollow part at both ends of the molded product. If the low resistance part is formed by coating with a means such as g Most of the electric current that passes through the end passes through this low resistance part, so it passes through the shaft body. The current is extremely small, and the amount of heat generated from the outer and inner circumferences of the shaft is greatly reduced. It [0015] In the second invention, when the heat roller is excessively heated, this temperature is It is also sensed by the power supply brush that is slid on the outer peripheral surface of the end of the tracker. The power supply brush is deformed by the bimetal function to cut off the power supply to the heat roller. It [0016] In the third invention, when the heat roller is excessively heated, this temperature is The power supply brush and the power supply in the circuit in the vicinity of the controller. The current cutoff circuit cuts off the power supply. [0017] 【Example】 Next, the details of the present invention will be described based on the illustrated embodiment. Figure 1 is applied to the present invention It is explanatory drawing which shows the outline of the heat roller used. In the figure, 1 is a cylindrical heating part Reference numeral 2 in the drawing denotes a tubular shaft portion projecting from both ends of the heat generating portion 1. The heating unit 1 in the example It is hollow but can be solid. The heat generating part 1 and the tubular shaft part 2 are made of conductive conductive material. It is integrally molded using Ramix. As a material for the heat generating part 1 and the tubular shaft part 2. It is also possible to use a material other than conductive ceramics, for example, a metal. It is desirable that the range of electric resistance between the two shaft ends is set to 5 Ω to 100 Ω. If this is less than 5 Ω, the amount of heat generated is too large and the heat resistance of the peripheral members will become a problem. This is because the conductive ceramics themselves may be deteriorated due to heat. This is because the heat generation amount is too small to heat-fix the toner. [0018] The heat roller is rotatably supported by bearings P, and is installed on the inner surface of the shaft at both ends. Power is supplied from the power supply brush R via the communication terminal S. The bearing P is barely Of course, metal, polyimide, or polyamide imid in which an inorganic sliding material is dispersed. It is also possible to use a heat resistant resin such as resin. Heat roller It is appropriately selected in consideration of the temperature, the life, etc. [0019] According to a first aspect of the present invention, in the heat roller having the above-mentioned structure, the power feeding brush R is made of bimetal. The feature is that the current interruption function used is added. Bimetal is thermal expansion Bond two kinds of metal with different tension and combine this with the contact, and It has a contact that opens and closes, and has an extremely simple structure and ensures reliable operation. You can wait. The present invention provides this power supply brush R with this bimetal function. Therefore, for example, as shown in FIGS. 2 (a) and 2 (b), two kinds of metals m1 having different thermal expansion coefficients, The conductive contact pieces 3 and 3 having spring elasticity formed by bonding m2 to each other are provided between the conductive ends. A structure in which the child S is arranged so as to be able to sandwich the child S is adopted. Conductivity When the surface temperature of the heat roller rises above a predetermined temperature, the contact pieces 3 and 3 are As shown in FIG. 3, due to the elasticity of the elastic member, it is bent back outward, and the inner surface of the conductive terminal S The power supply to the heat roller is cut off from the power source. And heat roller When the surface temperature of is below a predetermined temperature, the conductive contact pieces 3 and 3 are restored to their original shape. After returning to the state in which the conduction terminal S is clamped, the power supply to the heat roller is restarted. Of. [0020] In the above-described embodiment, the opposing conductive contact pieces that constitute the power feeding brush R are both connected to each other. It had a tal function, but it is possible to give a bimetal function to only one side. It is possible. It is also possible to give a part of the conductive contact piece a bimetal function. Further, the shape of the power feeding brush R can be changed to another shape, for example, as shown in FIG. It is also possible to use a substantially U-shaped object in which the opposing conductive contact pieces 3a, 3a are integrated. . When such a shape is adopted, the power feeding brush R is attached by one screw 4. Therefore, the power feeding brush R can be easily attached. [0021] In FIGS. 2 and 3, a metal plate is bent in a roll shape as the conduction terminal S. Is used. This is because the conductive terminal S can be elastically expanded and contracted in the radial direction, The contact with the inner wall of the part is made close to improve the conduction, and the thermally expanded conduction terminal S is It prevents the shaft end made of ceramics that does not expand so much from breaking. It [0022] As the conductive terminal S, other one can be adopted as long as it elastically expands and contracts in the radial direction. It is also possible to use a coil-shaped conducting terminal 5 as shown in FIG. 5, for example. Koi Even if one end of the coil-shaped conducting terminal 5 is fitted in the hollow portion of the shaft end, the free end side is a coil-shaped conducting terminal. Since the child 5 can move relatively freely by being deformed, such a coil shape If a conduction terminal is used, the heat roller, conduction terminal and power supply bra This eliminates the need for high-precision alignment work for the blades, which significantly improves workability. Reference numeral 6 in the figure denotes an annular member externally fitted to the end of the coil-shaped conducting terminal. After setting, the terminal 5 can be easily set on the power supply brush R and after setting. Holds the coil-shaped conducting terminal 5 rotatably, Electrical connection between the communication terminal 5 and the power feeding brush R is guaranteed. [0023] Reference numeral 7 in the figure indicates that the inner surface of the shaft end is in good contact with the coil-shaped conductive terminal S1 and In order to reduce the heat load on the peripheral parts such as the receiver, to avoid the temperature rise of the shaft end, Conductive metal is deposited on the inner surface of the void by vapor deposition, plating or coating. It is a low resistance portion that is arranged. The low resistance portion 7 is extremely thin and its material is Soft metals such as luminium and copper are used. As means for providing the low resistance portion 7 According to these means, vapor deposition, plating or coating is used for the surface of the molded product. Since the conductive metal can be coated so as to fill the undulating shape of the This is because it becomes possible to charge electricity. In the illustrated example, the length of the low resistance portion 7 is approximately the same as the length of the shaft portion 2. Although they almost match, this length is set appropriately. The length of the low resistance part 7 is the maximum Since it is enough to secure the length of the part, it is also possible to cover the conductive metal by vapor deposition etc. It's extremely easy. Also, the low resistance portion 7 is formed on the entire inner circumference of the hollow portion. It is also possible to provide it, but it may be provided in part. Conductive coating on the inner surface of the hollow part Since a soft material is used for the conductive metal, the conductive terminal and the inner surface of the hollow part The contact is very good. And coiled against such a heat roller When a voltage is applied via the conduction terminal S1, the contact with the coiled conduction terminal Most of the inflowing current passes through the low resistance portion 7 covered on the inner peripheral surface of the shaft end, The current passing through the body of the part 2 is extremely small, and the amount of heat generated on the inner and outer surfaces of the shaft is It can be significantly reduced. Therefore, the heat load on the bearing P is small and the heat resistance is high. Since it is possible to use bearings with low performance, it is cheaper than previously possible. It is possible to use various bearings. [0024] FIGS. 6 (a) and 6 (b) show a second invention, in which power is supplied to the heat roller by both heat roller. This is applied in the case where it is performed through a power feeding brush R'which is in sliding contact with the outer circumference of the end portion. First In the second invention, as shown in FIG. 6B, the end portion of the heat roller is slidably contacted with the outer circumference. The power feeding brush R'is made of bimetal. In the second invention, When the temperature of the roller rises excessively, the power supply brush R'which is in sliding contact with the heat roller warps back. The power supply to the heat roller is cut off. [0025] What is shown as FIG. 7 is a third device. The above-mentioned first and second inventions are provided. Whereas the electric brush itself had a bimetal function, the third invention is a bar brush. Powering a current interruption circuit 10 consisting of a spring elastic piece 8 having an imetal function and a counter contact 9 Separately from the brush R ″, the current cut-off circuit 10 senses the temperature of the heat roller surface. The heat cutoff circuit 10 supplies electric power to the heat roller. It is characterized by being interposed in the circuit between the power supply brush R "to be supplied and the power supply. . In the third invention, when the heat roller is excessively heated, the current interruption circuit 10 is constructed. If the spring elastic piece 8 bends back and the current is cut off and the temperature is lowered to a predetermined temperature, the spring elasticity The piece 8 is restored and power supply is restarted. [0026] In this way, the heat roller of the present invention imparts a bimetal function to the power feeding brush itself. Or a current cutoff circuit having a bimetal function between the power supply brush and the power supply As the heat roller is overheated, the The power supply to the heat roller can be cut off by operating the switch. And the current interruption As a result, when the temperature drops below the specified temperature, the bimetal immediately returns. Power supply is restarted. Therefore, the surface temperature of the heat roller can be maintained constant, To prevent deterioration of the heat roller and peripheral parts and the occurrence of fire due to excessive temperature rise. And are possible. Moreover, since the present invention uses bimetal, the structure is It is simple, can be miniaturized, and is extremely inexpensive, making it easy to adapt to mass-produced products. Is. [0027] [Effect of the device] The heat roller in the fixing device of the present invention is a bimetal machine on the power supply brush itself. Function or a power supply using a bimetal function between the power supply brush and the power supply. Since the flow cutoff circuit is provided, the heat roller can be specified with a simple and inexpensive structure. It is possible to maintain the temperature and deterioration of peripheral parts due to excessive temperature rise. The risk of fire and fire can be completely prevented. Especially, the first and second devices are Since the electric brush itself has a bimetal function, it has a bimetal function. Since the installation space is not required separately, the heat roller becomes larger. It never happens. [0028] In addition, a coil-shaped conduction terminal is used as a conduction terminal that supplies power from the power supply brush to the shaft. When used, a good energization state between the conduction terminal and the inner surface of the hollow shaft end can be guaranteed. In addition, at the time of assembly, the heat roller, conduction terminal and power supply brush are combined with high precision. Workability is significantly improved. [0029] Also, an annular member shorter than the coil-shaped conducting terminal is externally fitted to the end of the coil-shaped conducting terminal. In addition, it is easy to connect the power supply brush and the conduction terminal, and the coiled conduction The conduction between the terminal and the power supply brush is also good. [0030] Further, a soft conductive metal is vapor-deposited on a part or all of the inner surface of the hollow part at both ends of the molded body, If the low resistance part is formed by coating by means such as plating or coating, Most of the current passing through the end of the body passes through this low resistance part, so it passes through the shaft body. The current generated is extremely small, and the amount of heat generated from the inner and outer circumferences of the shaft is significantly reduced. It can be lowered, and the load on the bearing and peripheral parts can be reduced.

【図面の簡単な説明】【図１】本考案が適用されるヒートローラーの概略を示
す説明図【図２】（イ）は第１考案のヒートローラを示す部分断
面説明図、（ロ）は同ヒートローラにおける導通端子を
抱持した給電ブラシを示す断面説明図【図３】同ヒートローラにおいて導通端子を解放した状
態の給電ブラシを示す断面説明図【図４】給電ブラシの他の実施例を示す断面説明図【図５】（イ）はコイル状導通端子を用いた第１考案に
かかるヒートローラを示す部分断面説明図、（ロ）は同
ヒートローラにおける導通端子を抱持した給電ブラシを
示す断面説明図【図６】（イ）は第２考案のヒートローラを示す平面説
明図、（ロ）は同側面説明図【図７】第３考案のヒートローラを示す説明図【図８】定着装置の概要を示す説明図【図９】従来のヒートローラーの１例を示す断面図【図10】従来のヒートローラーの他の例を示す断面図【図11】従来のヒートローラーにおける導通端子と給電
ブラシの取付け関係を示す説明図【符号の説明】ＡヒートローラーＢ押えローラーＣ記録紙Ｐ軸受Ｓ導通端子Ｒ給電ブラシＲ’給電ブラシＲ”給電ブラシａ発熱体ｂ摺動片ｃ軸部１発熱部２管状軸部３導電性接触片 3a 導電性接触片４ビス５コイル状導通端子６環状部材７低抵抗部８バネ弾性片９対向接点 10 電流遮断回路BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an explanatory view showing an outline of a heat roller to which the present invention is applied. FIG. 2 (a) is a partial sectional explanatory view showing the heat roller of the first invention, and (b) is Cross-sectional explanatory view showing a power supply brush holding a conductive terminal in the heat roller. [FIG. 3] Cross-sectional explanatory view showing a power supply brush in the same heat roller with the conductive terminal released. [FIG. 4] Another embodiment of the power supply brush 5A is a partial cross-sectional explanatory view showing the heat roller according to the first invention using a coil-shaped conductive terminal, and FIG. 5B is a power supply brush holding the conductive terminal in the heat roller. FIG. 6 (a) is an explanatory plan view showing the heat roller of the second invention, (b) is an explanatory side view of the same, and FIG. 7 is an explanatory view showing the heat roller of the third invention. Explanatory view showing the outline of the fixing device [FIG. 9] Conventional FIG. 10 is a cross-sectional view showing an example of the heat roller of FIG. 10. FIG. 10 is a cross-sectional view showing another example of the conventional heat roller. Description A heat roller B presser roller C recording paper P bearing S conduction terminal R power supply brush R'power supply brush R "power supply brush a heating element b sliding piece c shaft section 1 heating section 2 tubular shaft section 3 conductive contact piece 3a Conductive contact piece 4 Screw 5 Coil-shaped conductive terminal 6 Annular member 7 Low resistance part 8 Spring elastic piece 9 Opposing contact 10 Current interruption circuit

Claims

[Claims for utility model registration] 1. In a heat roller in a fixing device having a shaft portion projecting from both ends of the heat generating portion, the heat generating portion and the shaft portion are integrally molded of the same material, A conductive terminal is tightly fitted to both hollowed end portions, and at least one of the conductive terminals is configured by arranging conductive contact pieces to face each other, and at least one conductive contact piece has a spring elasticity having a bimetal function. A heat roller in a fixing device, which is sandwiched by a power supply brush that is one side and receives power. 2. The heat roller in the fixing device according to claim 1, wherein a coil-shaped one is used as the conduction terminal. 3. The fixing device according to claim 1, wherein an annular member shorter than the coil-shaped conductive terminal is interposed between the coil-shaped conductive terminal and the power supply brush while being fitted onto the coil-shaped conductive terminal. Heat roller. 5. A soft conductive metal is coated on a part or all of the inner surface of the hollow part at both ends of the molded body by means such as vapor deposition, plating or coating.
A heat roller in the fixing device described. 6. A heat roller in a fixing device in which a shaft portion is provided at both ends of a heat generating portion, wherein the heat generating portion and the shaft portion are integrally formed of the same material, and the outer peripheral surface of the end portion of the heat roller is slid. A heat roller in a fixing device, characterized in that a spring elastic piece having a bimetal function is used as a power supply brush in contact therewith. 7. In a heat roller of a fixing device, a current interruption circuit composed of a spring elastic piece having a bimetal function and a counter contact is arranged at a position where the temperature of the surface of the heat roller can be sensed, and the current interruption circuit is provided with the heat roller. A heat roller in a fixing device that is interposed in the circuit between a power supply brush that supplies power to the roller and a power supply.