JP6729134B2 - Rotational force transmission mechanism, and fixing device and image forming apparatus including the same - Google Patents

Rotational force transmission mechanism, and fixing device and image forming apparatus including the same Download PDF

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JP6729134B2
JP6729134B2 JP2016147455A JP2016147455A JP6729134B2 JP 6729134 B2 JP6729134 B2 JP 6729134B2 JP 2016147455 A JP2016147455 A JP 2016147455A JP 2016147455 A JP2016147455 A JP 2016147455A JP 6729134 B2 JP6729134 B2 JP 6729134B2
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gear
tooth
toothless
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JP2018017299A (en
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邦彦 鳴瀬
邦彦 鳴瀬
将浩 椎木
将浩 椎木
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Konica Minolta Inc
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Description

本発明は画像形成装置に関し、特に定着ローラーに対する回転力伝達機構に関する。 The present invention relates to an image forming apparatus, and more particularly to a rotational force transmission mechanism for a fixing roller.

プリンター、コピー機等の画像形成装置は、シート搬送機構、印刷エンジン等の機械的要素（「メカニカルコンポーネント」、略して「メカコン」という。）を含む。メカコン内では、搬送ローラー、ポリゴンミラー、感光体ドラム等に見られる（準）定常的な回転運動が典型的である。その他にも、ピックアップローラーによるシートの繰り出し、クラッチによる搬送ローラーに対する回転力の遮断等、間欠的な運動が多用される。 An image forming apparatus such as a printer or a copier includes mechanical elements such as a sheet conveying mechanism and a print engine (“mechanical component”, abbreviated as “mechacon”). In the mechanical controller, the (quasi) steady rotational motion found in the transport roller, the polygon mirror, the photosensitive drum, etc. is typical. In addition, intermittent movements such as feeding of a sheet by a pickup roller and interruption of a rotational force by a clutch to a conveyance roller are often used.

間欠的な運動の駆動系統では欠歯ギアが駆動力の伝達によく利用される。「欠歯ギア」とは、周の一部に歯がないギアをいう。駆動ギアが定常的に回転する場合、欠歯ギアは、歯のある周部分（「有歯部」という。）が駆動ギアと噛み合う姿勢（以下、「回転姿勢」と呼ぶ。）を取る間、駆動ギアから回転力を受けて回転する。有歯部が駆動ギアから離脱すると駆動ギアからの回転力が途絶えるので欠歯ギアは停止し、歯のない周部分（「欠歯部」という。）が駆動ギアに面する姿勢（以下、「停止姿勢」と呼ぶ。）を維持する。駆動ギアとは別の駆動力源（以下、「初動部材」と呼ぶ。）が欠歯ギアの有歯部を駆動ギアに再び噛み合わせると欠歯ギアは回転を再開する。このようにして欠歯ギアは、駆動ギアの定常的な回転から間欠的な回転を引き出すのに利用される。画像形成装置では欠歯ギアがたとえば、ピックアップローラーによるシートの繰り出し（特許文献１、２参照。）、搬送ローラーのクラッチ（特許文献３参照。）、定着ローラーからの均熱ローラー（特許文献４、５参照。）の離間に利用される。 In intermittent drive systems, toothless gears are often used to transmit drive force. The "partial tooth gear" refers to a gear that has no teeth on part of its circumference. When the drive gear rotates steadily, the tooth-missing gear takes a posture in which a toothed peripheral portion (referred to as “toothed portion”) meshes with the drive gear (hereinafter, referred to as “rotational posture”). It receives the rotational force from the drive gear and rotates. When the toothed portion disengages from the drive gear, the rotational force from the drive gear is interrupted, so the toothless gear stops, and the toothless peripheral portion (referred to as "toothless portion") faces the drive gear (hereinafter referred to as "the toothless portion"). Called "stop posture"). When a driving force source (hereinafter, referred to as “initial moving member”) different from the driving gear re-engages the toothed portion of the toothless gear with the driving gear, the toothless gear restarts rotation. In this way, the tooth-missing gear is used to extract intermittent rotation from the steady rotation of the drive gear. In the image forming apparatus, the partly toothless gear is, for example, a sheet feeding by a pickup roller (see Patent Documents 1 and 2), a clutch of a conveying roller (see Patent Document 3), a heat equalizing roller from a fixing roller (Patent Document 4, (See 5)).

欠歯ギアの有歯部では、回転方向の先頭に位置する歯の歯先が切り欠かれる場合がある（特許文献６、７参照）。この切り欠きにより、有歯部が駆動ギアと噛み合い始める際、歯先が設計上の咬合位置から外れても駆動ギアの歯先と衝突すること（以下、「歯先当たり」と呼ぶ。）が回避される。その結果、歯先当たりに起因する騒音が低減し、ギアのロック、共振等、駆動力伝達の不具合が抑えられ、歯面損傷によるギアの短寿命化が防止される。 In the toothed portion of the tooth-missing gear, the tip of the tooth located at the head in the rotation direction may be cut out (see Patent Documents 6 and 7). Due to the notch, when the toothed portion starts to mesh with the drive gear, the tooth tip may collide with the tooth tip of the drive gear (hereinafter, referred to as “tooth tip contact”) even if the tooth tip deviates from the designed meshing position. Avoided. As a result, the noise caused by the tooth tip contact is reduced, defects in driving force transmission such as gear locking and resonance are suppressed, and shortening of the gear life due to tooth surface damage is prevented.

１つの駆動ギアに対して欠歯ギアは、２枚が同軸に重ね合わされて利用される場合がある（特許文献１−３参照）。２枚の欠歯ギアが両方とも停止姿勢を維持するとき、初動部材はそれらの一方のみを回転姿勢に移行させる。他方の欠歯ギアは、先に回転姿勢を取った欠歯ギアから回転力を受けて回転姿勢に移行する。こうして、両方の欠歯ギアが駆動ギアの回転力を負荷へ伝達する。この場合、欠歯ギアが１枚だけである場合と比べ、初動部材が回転させるべき欠歯ギアの慣性モーメントは、負荷へ伝達すべき回転力を高く維持したまま軽減可能である。したがって、初動部材の負担が軽減される。さらに、駆動ギアが各欠歯ギアと噛み合い始める際にその欠歯ギアから受ける抗力が低く抑えられるので、歯先当たりに起因する騒音、ギアのロック、歯面損傷等が抑制される。 Two toothless gears may be coaxially overlapped with one drive gear and used (see Patent Documents 1-3). When both of the two toothless gears maintain the stopped posture, the initial member shifts only one of them to the rotating posture. The other partly tooth-missing gear receives the rotational force from the partly tooth-missing gear that has previously taken the rotation posture and shifts to the rotation posture. Thus, both toothless gears transmit the rotational force of the drive gear to the load. In this case, as compared with the case where there is only one toothless gear, the moment of inertia of the toothless gear to be rotated by the initial member can be reduced while maintaining a high rotational force to be transmitted to the load. Therefore, the load on the initial moving member is reduced. Further, when the drive gear starts to mesh with each tooth-missing gear, the drag force received from the tooth-missing gear is suppressed to a low level, so that noise, gear locking, tooth surface damage, etc. due to tooth tip contact are suppressed.

特開２００８−００２５６９号公報JP, 2008-002569, A 特開２００９−１０７８２６号公報JP, 2009-107826, A 特開２０１２−０７６９１１号公報JP 2012-076911 A 特開２０１０−００２６９１号公報JP, 2010-002691, A 特開２０１４−０５２４６７号公報JP, 2014-052467, A 特開平０８−２２６５１７号公報JP-A-08-226517 特開２０１４−０１０２７６号公報JP, 2014-010276, A

２枚の欠歯ギアが同軸に重ね合わされて使用される場合、これらの欠歯ギア間には回転姿勢の位相（基準方向から特定の歯が位置する半径方向までの角度）に差が生じにくい。これは、２枚の欠歯ギアのうち先に回転姿勢を取った方が他方を停止姿勢から回転姿勢へ移行させ、その後、他方と一体的に回転することによる。したがって、前者が駆動ギアにうまく噛み合えさえすれば、後者は自動的に駆動ギアとうまく噛み合う。 When two tooth-missing gears are coaxially overlapped and used, the phase difference of the rotation posture (angle from the reference direction to the radial direction where a specific tooth is located) is unlikely to occur between these tooth-missing gears. .. This is because, of the two toothless gears, the one that takes the rotation posture first shifts the other from the stop posture to the rotation posture, and then rotates integrally with the other. Therefore, if the former only meshes well with the drive gear, the latter will automatically mesh well with the drive gear.

しかし、欠歯ギアとシャフトとの間、または２枚の欠歯ギア間のガタ（遊び）が無視できない場合、２枚の欠歯ギアが一体的に回転する際における両ギア間の位相差が過大になりやすい。これは、ガタに伴う各欠歯ギアの回転の不安定性が無視できないことによる。この場合、１枚目の欠歯ギアが駆動ギアにうまく噛み合った状態でも、２枚目の欠歯ギアが駆動ギアに噛み合う際に歯先当たりが生じる危険性が高い。その結果、その歯先当たりに起因する騒音の低減が阻まれ、さらに、ギアのロック等の不具合と歯面損傷との防止が困難である。 However, when the backlash (play) between the toothless gear and the shaft or between the two toothless gears cannot be ignored, the phase difference between the two toothless gears when they rotate integrally It is easy to oversize. This is because the instability of rotation of each toothless gear due to backlash cannot be ignored. In this case, even if the first toothless gear meshes well with the drive gear, there is a high risk of tooth tip contact when the second toothless gear meshes with the drive gear. As a result, it is difficult to reduce noise due to the contact of the tooth tips, and it is difficult to prevent troubles such as gear locking and tooth surface damage.

特に、定着ローラーから均熱ローラー等の他のローラーを間欠的に離間させる機構（特許文献５参照。）には２枚重ねの欠歯ギアを適用することが難しい。これは次の理由に因る。定着部の動作温度の許容上限は一般に数百℃もの高温である。このような高温に定着ローラー等の可動部材が長時間曝される最悪の状態においても、シャフト、ギア等、回転力伝達機構の構成要素の間隔には各要素の熱膨張に起因する詰まりが生じないように、その間隔のガタは十分に大きな値に設計される。これにより、高温環境下での動作においてもギア等の熱膨張に起因する摩擦力が適度な強さに抑えられるので、過大な摩擦音、ギアのロック、摩擦熱による過熱等の不具合が防止される。しかし、その反面、たとえば、電源投入直後、もしくはリカバリー直後、定着ローラーの高熱が周辺の部材にまでは伝わっていない状態のように比較的低温の環境下では、無視できない大きさのガタが残る。このガタにより、２枚の欠歯ギアを安定に回転させてそれらの間の位相差を無視可能な程度に小さく抑えることが阻まれる。 In particular, it is difficult to apply a two-toothed toothless gear to a mechanism that intermittently separates another roller such as a heat equalizing roller from the fixing roller (see Patent Document 5). This is due to the following reasons. The upper limit of the operating temperature of the fixing unit is generally as high as several hundreds of degrees Celsius. Even in the worst state where a movable member such as a fixing roller is exposed to such a high temperature for a long time, the gaps between the components of the rotational force transmission mechanism such as the shaft and gears are blocked due to thermal expansion of each component. The play of the interval is designed to be a sufficiently large value so that there is no gap. As a result, the frictional force caused by the thermal expansion of the gears can be suppressed to an appropriate level even in the operation in a high temperature environment, so that problems such as excessive friction noise, gear locking, and overheating due to frictional heat can be prevented. .. However, on the other hand, for example, in a relatively low temperature environment, such as a state where the high heat of the fixing roller is not transmitted to the peripheral members immediately after the power is turned on or immediately after recovery, there is a play that cannot be ignored. This backlash prevents stable rotation of the two toothless gears and suppresses the phase difference between them to a negligible level.

本発明の目的は上記の課題を解決することであり、特に、欠歯ギアとシャフトとの間、または２枚の欠歯ギア間のガタが無視できない場合でも、欠歯ギアが駆動ギアに噛み合う際に歯先当たりが生じる危険性を回避可能な回転力伝達機構を提供することにある。 An object of the present invention is to solve the above-mentioned problems, and in particular, even when the play between the tooth-missing gear and the shaft or between the two tooth-missing gears cannot be ignored, the tooth-missing gear meshes with the drive gear. An object of the present invention is to provide a rotational force transmission mechanism capable of avoiding the risk of tip contact at the time.

本発明の１つの観点による回転力伝達機構は、定常的に回転する１枚の駆動ギアの回転力を利用して可動部材を間欠的に変位させる。この回転力伝達機構は、それぞれの有歯部が駆動ギアに噛み合う回転姿勢を取ることのできるように同軸に配置された１対の欠歯ギアであり、回転姿勢を維持する間は同方向へ回転し、有歯部が駆動ギアから離脱すると、欠歯部が駆動ギアに面する停止姿勢を維持する第１欠歯ギアおよび第２欠歯ギアと、第１欠歯ギアを停止姿勢から回転姿勢へ移行させる初動部材と、第１欠歯ギアと一体に形成され、回転姿勢の第１欠歯ギアから回転力を第２欠歯ギアへ伝達することにより、第２欠歯ギアを停止姿勢から回転姿勢へ移行させる伝達部材と、第２欠歯ギアの回転力で回転して外部の固定部材または可動部材との接触点を移動させることにより、固定部材に対して可動部材を変位させるカムとを備えている。初動部材は、第１欠歯ギアと第２欠歯ギアとの間に周方向の力を加える付勢部材としてのバネと、付勢部材の加える力に抗して第１欠歯ギアを停止姿勢に保持する保持部材と、保持部材を変位させて第１欠歯ギアの保持を解除させる駆動部と、を含む。第１欠歯ギアの有歯部において回転方向の先頭に位置する歯は、歯先が切り欠かれた傾斜面を含み、当該傾斜面は、回転方向の端部が逆方向の端部よりも前記第１欠歯ギアの中心に近い。第２欠歯ギアの有歯部において回転方向の先頭に位置する歯は、歯先が切り欠かれた傾斜面を含み、当該傾斜面は、回転方向の端部よりも逆方向の端部が前記第２欠歯ギアの中心に近い。
本発明の別の態様としての回転力伝達機構は、それぞれの有歯部が駆動ギアに噛み合う回転姿勢を取ることのできるように同軸に配置された１対の欠歯ギアであり、回転姿勢を維持する間は同方向へ回転し、有歯部が駆動ギアから離脱すると、欠歯部が駆動ギアに面する停止姿勢を維持する第１欠歯ギアおよび第２欠歯ギアと、第１欠歯ギアを停止姿勢から回転姿勢へ移行させる初動部材と、回転姿勢の第１欠歯ギアから回転力を第２欠歯ギアへ伝達することにより、第２欠歯ギアを停止姿勢から回転姿勢へ移行させる伝達部材と、第２欠歯ギアの回転力で回転して外部の固定部材または可動部材との接触点を移動させることにより、固定部材に対して可動部材を変位させるカムと、を備えている。第２欠歯ギアの有歯部は、回転方向の先頭に位置する歯の歯先が切り欠かれている。初動部材は、第１欠歯ギアと第２欠歯ギアとの間に周方向の力を加える付勢部材と、付勢部材の加える力に抗して第１欠歯ギアを停止姿勢に保持する保持部材と、保持部材を変位させて第１欠歯ギアの保持を解除させる駆動部と、を含む。第１欠歯ギアの表面には、第１欠歯ギアと同心で、半径が互いに異なる複数の弧状部分を含む溝が刻まれており、保持部材は、先端が溝の中に位置し、かつ第１欠歯ギアの半径方向に変位可能に支持された突起部を含む。突起部は先端を、溝のうち、いずれかの弧状部分の端に接触させることにより第１欠歯ギアを停止姿勢に保持し、駆動部は、突起部を第１欠歯ギアの半径方向に変位させて突起部の先端を溝の別の弧状部分へ移動させることにより、保持部材に第１欠歯ギアの保持を解除させる。 The rotational force transmission mechanism according to one aspect of the present invention intermittently displaces the movable member by utilizing the rotational force of one drive gear that constantly rotates. This rotational force transmission mechanism is a pair of toothless gears that are coaxially arranged so that each toothed portion can take a rotational posture in which it meshes with the drive gear, and in the same direction while maintaining the rotational posture. When the toothed portion rotates and the toothed portion disengages from the drive gear, the first toothless gear and the second toothless gear that maintain the stopped posture in which the toothless portion faces the drive gear, and the first toothless gear rotate from the stopped posture The first partly toothed gear that shifts to the posture and the first partly toothed gear are integrally formed , and the second partly toothed gear is stopped by transmitting the rotational force from the first partly toothless gear in the rotating position to the second partly toothed gear. A cam for displacing the movable member with respect to the fixed member by moving the contact point between the transmission member that shifts from the rotational position to the rotational posture and the rotational force of the second toothless gear to move the contact point with the external fixed member or the movable member. It has and. The initial motion member is a spring as an urging member that applies a force in the circumferential direction between the first toothless gear and the second toothless gear, and stops the first toothless gear against the force applied by the urging member. A holding member that holds the posture and a drive unit that displaces the holding member to release the holding of the first toothless gear are included. The tooth located at the head in the rotation direction in the toothed portion of the first toothless gear includes an inclined surface with a tooth tip cut out, and the inclined surface has an end portion in the rotation direction more than an end portion in the opposite direction. It is close to the center of the first toothless gear. The tooth located at the head in the rotation direction in the toothed portion of the second partly tooth-missing gear includes an inclined surface with a tooth tip cut out, and the inclined surface has an end portion in the direction opposite to the end portion in the rotation direction. It is close to the center of the second toothless gear.
According to another aspect of the present invention, there is provided a rotational force transmission mechanism, which is a pair of toothless gears coaxially arranged so that each toothed portion can take a rotational posture in which it meshes with a drive gear. When the toothed portion disengages from the drive gear while maintaining, the first toothless gear and the second toothless gear that maintain the stopped posture in which the toothless portion faces the drive gear, and the first toothless gear. The initial member that shifts the tooth gear from the stopped posture to the rotation posture and the rotational force from the first tooth-missing gear in the rotation posture to the second tooth-missing gear to move the second tooth-missing gear from the stopping posture to the rotating posture. And a cam for displacing the movable member with respect to the fixed member by moving the contact point between the transmission member to be moved and the external fixed member or the movable member by rotating with the rotational force of the second toothless gear. ing. The toothed portion of the second partly tooth-missing gear has the tip of the tooth located at the head in the rotation direction cut out. The initial moving member holds a biasing member that applies a force in the circumferential direction between the first toothless gear and the second toothless gear, and holds the first toothless gear in a stopped posture against the force applied by the biasing member. And a drive unit that displaces the holding member to release the holding of the first tooth-missing gear. The surface of the first partly tooth-missing gear is carved with a groove that is concentric with the first partly tooth-missing gear and includes a plurality of arcuate portions having different radii, and the holding member has a tip located in the groove and It includes a protrusion supported so as to be displaceable in the radial direction of the first toothless gear. The protrusion holds the first partly tooth-missing gear in a stopped posture by bringing the tip into contact with the end of any one of the arcuate portions of the groove, and the drive part causes the protrusion to move in the radial direction of the first partly-missing gear. By displacing and moving the tip of the protrusion to another arcuate portion of the groove, the holding member releases the holding of the first tooth-missing gear.

第２欠歯ギアの有歯部において回転方向の先頭に位置する歯は、歯先が切り欠かれた傾斜面を含み、当該傾斜面は、回転方向の端部よりも逆方向の端部が前記第２欠歯ギアの中心に近くてもよい。この歯は、歯先の表面に、第２欠歯ギアの中心からの距離が第２欠歯ギアのピッチ円の半径よりも長い部分を含んでもよい。
第１欠歯ギアの有歯部は、回転方向の先頭に位置する歯の歯先が切り欠かれていてもよい。第１欠歯ギアの有歯部において回転方向の先頭に位置する歯は、歯先が切り欠かれた傾斜面を含み、当該傾斜面は、回転方向の端部が逆方向の端部よりも前記第１欠歯ギアの中心に近くてもよい。この歯は、歯先の表面に、第１欠歯ギアの中心からの距離が第１欠歯ギアのピッチ円の半径よりも長い部分を含んでもよい。 The tooth located at the head in the rotation direction in the toothed portion of the second partly tooth-missing gear includes an inclined surface with a tooth tip cut out, and the inclined surface has an end portion in the direction opposite to the end portion in the rotation direction. it may be close rather the center of the second segment gear. This tooth may include a portion on the surface of the tooth tip whose distance from the center of the second tooth-missing gear is longer than the radius of the pitch circle of the second tooth-missing gear.
The toothed portion of the first partly tooth-missing gear may have the tip of the tooth located at the head in the rotation direction cut out. The tooth located at the head in the rotation direction in the toothed portion of the first toothless gear includes an inclined surface with a tooth tip cut out, and the inclined surface has an end portion in the rotation direction more than an end portion in the opposite direction. it may be close rather the center of the first segment gear. This tooth may include a portion on the surface of the tooth tip whose distance from the center of the first tooth-missing gear is longer than the radius of the pitch circle of the first tooth-missing gear.

付勢部材は、一端が第１欠歯ギアに固定され、他端が第２欠歯ギアに固定されたバネを含んでもよい。このバネは、保持部材が第１欠歯ギアを停止姿勢に保持する間、第２欠歯ギアの回転により復元力を高め、駆動部が保持部材に第１欠歯ギアの保持を解除させるのに伴い、その復元力で第１欠歯ギアを第２欠歯ギアに対して回転させてもよい。第１欠歯ギアの表面には、第１欠歯ギアと同心で、半径が互いに異なる複数の弧状部分を含む溝が刻まれていてもよい。保持部材は、歯先がこの溝の中に位置し、かつ第１欠歯ギアの半径方向に変位可能に支持された突起部を含んでもよい。この突起部は歯先を、この溝のうち、いずれかの弧状部分の端に接触させることにより第１欠歯ギアを停止姿勢に保持してもよい。駆動部は、この突起部を第１欠歯ギアの半径方向に変位させてこの突起部の歯先を溝の別の弧状部分へ移動させることにより、保持部材に第１欠歯ギアの保持を解除させてもよい。 Biasing member has one end fixed to the first segment gear may include a spring whose other end is fixed to the second segment gear. This spring increases the restoring force by the rotation of the second tooth-missing gear while the holding member holds the first tooth-missing gear in the stopped posture, and the drive unit causes the holding member to release the holding of the first tooth-missing gear. Accordingly, the restoring force may rotate the first toothless gear with respect to the second toothless gear. The surface of the first partly tooth-missing gear may be engraved with a groove that is concentric with the first partly tooth-missing gear and that includes a plurality of arc-shaped portions having different radii. The holding member may include a protrusion whose tip is located in the groove and which is supported so as to be displaceable in the radial direction of the first toothless gear. The protrusion may hold the first tooth-missing gear in the stopped posture by bringing the tip of the tooth into contact with the end of any one of the arcuate portions of the groove. The drive unit displaces the protrusion in the radial direction of the first tooth-missing gear to move the tooth tips of the protrusion to another arcuate portion of the groove, so that the holding member holds the first tooth-missing gear. You may cancel it.

第１欠歯ギアに面した第２欠歯ギアの表面は、第２欠歯ギアと同心弧状の凹部を含んでもよい。伝達部材は、一端がこの凹部の中に位置し、他端が第１欠歯ギアに固定された柱状部を含んでもよい。この柱状部は、第１欠歯ギアの回転に伴い、一端で凹部の端を周方向に押すことにより、第２欠歯ギアを第１欠歯ギアの回転に連動して回転させてもよい。
第２欠歯ギアは、中心部から回転軸方向に突出するスリーブを同軸に含み、第１欠歯ギアは、このスリーブが挿入される穴を中心部に含んでもよい。第１欠歯ギアと第２欠歯ギアとの軸方向の間隔は、両欠歯ギアの温度が許容上限に達した場合でも実質的に詰まらない値に設計されていてもよい。 The surface of the second partly tooth-missing gear that faces the first partly tooth-missing gear may include a concave portion that is concentric with the second partly tooth-missing gear. The transmission member may include a columnar portion having one end located in the recess and the other end fixed to the first toothless gear. The columnar portion may rotate the second tooth-missing gear in conjunction with the rotation of the first tooth-missing gear by pushing the end of the recess in the circumferential direction with one end as the first tooth-missing gear rotates. ..
The second partly tooth-missing gear may coaxially include a sleeve that protrudes from the central portion in the rotation axis direction, and the first partly toothless gear may include a hole into which the sleeve is inserted in the central portion. The axial distance between the first partly tooth-missing gear and the second partly tooth-missing gear may be designed to a value that does not cause substantial clogging even when the temperature of both the partly tooth-missing gears reaches the allowable upper limit.

本発明の１つの観点による定着装置は、画像形成装置に搭載され、シートに画像を熱定着させる。この定着装置は、シートに接触して加熱する定着ローラーと、この定着ローラーを定常的に回転させるモーターと、定着ローラーに接触して従動回転する位置と定着ローラーから離間する位置との間で変位可能に支持された別ローラーと、モーターの回転力により定常的に回転する駆動ギアと、この駆動ギアの回転力を利用して別ローラーを定着ローラーから間欠的に離間させる上記の回転力伝達機構とを備えている。 A fixing device according to one aspect of the present invention is mounted on an image forming apparatus to thermally fix an image on a sheet. This fixing device displaces between a fixing roller that contacts and heats a sheet, a motor that constantly rotates the fixing roller, and a position where the fixing roller is driven to rotate and separated from the fixing roller. The other roller that can be supported, the drive gear that constantly rotates by the rotational force of the motor, and the rotational force transmission mechanism that intermittently separates the other roller from the fixing roller by using the rotational force of the drive gear. It has and.

本発明の１つの観点による画像形成装置は、シートを搬送する搬送装置と、シートに画像を作成する作像装置と、シートに画像を熱定着させる上記の定着装置とを備えている。 An image forming apparatus according to one aspect of the present invention includes a conveying device that conveys a sheet, an image forming device that forms an image on the sheet, and the fixing device that thermally fixes the image on the sheet.

本発明の１つの観点による回転力伝達機構では、同軸に配置された１対の欠歯ギアのうち、第１欠歯ギアが初動部材により停止姿勢から回転姿勢へ移行し、回転姿勢の第１欠歯ギアが第２欠歯ギアを停止姿勢から回転姿勢へ移行させる。この構成において、第２欠歯ギアの有歯部は、回転方向の先頭に位置する歯の歯先が切り欠かれている。これによりこの回転力伝達機構は、各欠歯ギアとシャフトとの間、または１対の欠歯ギア間のガタが無視できない場合でも、少なくとも第２欠歯ギアが駆動ギアに噛み合う際に歯先当たりが生じる危険性を回避可能である。 In the rotational force transmission mechanism according to one aspect of the present invention, of the pair of coaxially arranged toothless gears, the first toothless gear shifts from the stopped posture to the rotational posture by the initial moving member, and the first rotational posture is maintained. The tooth-chipped gear shifts the second tooth-chipped gear from the stop posture to the rotation posture. In this configuration, the toothed portion of the second partly tooth-missing gear has the tip of the tooth located at the head in the rotation direction cut out. As a result, the rotational force transmission mechanism is configured such that at least when the second tooth-missing gear meshes with the drive gear, at least when the play between the tooth-missing gears and the shaft or between the pair of tooth-missing gears cannot be ignored. The risk of hitting can be avoided.

（ａ）は、本発明の実施形態による画像形成装置の外観を示す斜視図である。（ｂ）は、（ａ）の示す直線Ｉｂ−Ｉｂに沿った模式的な断面図である。FIG. 1A is a perspective view showing the outer appearance of the image forming apparatus according to the embodiment of the present invention. (B) is a schematic cross-sectional view taken along a straight line Ib-Ib shown in (a). （ａ）は、図１の（ｂ）の示す定着ローラー、均熱ローラー、およびクリーニングローラーとそれらの駆動機構との模式的な斜視図である。（ｂ）は、（ａ）が示す駆動機構の周辺の外観を示す拡大斜視図である。1A is a schematic perspective view of a fixing roller, a soaking roller, and a cleaning roller shown in FIG. 1B, and a drive mechanism thereof. (B) is an enlarged perspective view showing the external appearance of the periphery of the drive mechanism shown in (a). （ａ）は、定着ローラーのフレームからギア列を除去したときの外観を示す拡大斜視図であり、（ｂ）は、（ａ）の示す構成から更に初動部材の一部を除去したときの外観を示す斜視図である。(A) is an enlarged perspective view showing an appearance when the gear train is removed from the frame of the fixing roller, and (b) is an appearance when a part of the initial moving member is further removed from the configuration shown in (a). It is a perspective view showing. （ａ）は、図３の（ｂ）の示す構成から初動部材を除去したときの外観を示す拡大斜視図である。（ｂ）は、均熱ローラーと欠歯ギアとの接続部の分解斜視図である。（ｃ）は、の（ａ）の示す直線ｃ−ｃに沿ったその接続部の断面図である。FIG. 3A is an enlarged perspective view showing the appearance when the initial moving member is removed from the configuration shown in FIG. (B) is an exploded perspective view of a connection part of a soaking roller and a toothless gear. (C) is sectional drawing of the connection part along the straight line cc shown to (a). （ａ）は第１欠歯ギアの表面を示す平面図であり、（ｂ）は第１欠歯ギアの裏面を示す平面図であり、（ｃ）は第１欠歯ギアの側面図である。(A) is a plan view showing the front surface of the first tooth-missing gear, (b) is a plan view showing the back surface of the first tooth-missing gear, and (c) is a side view of the first tooth-missing gear. .. （ａ）は、第２欠歯ギアの表面を示す平面図であり、（ｂ）は、第１欠歯ギアと第２欠歯ギアとの分解斜視図である。(A) is a top view which shows the surface of a 2nd tooth-missing gear, (b) is an exploded perspective view of a 1st tooth-missing gear and a 2nd tooth-missing gear. （ａ）は、軸方向から見たときの、定着ローラー、駆動ギア、および欠歯ギアの位置を示す側面図であり、（ｂ）は、（ａ）から駆動ギアと第１欠歯ギアとを除去したときの側面図であり、（ｃ）は、（ｂ）からローラー以外の部材をすべて除去したときの側面図である。(A) is a side view showing the positions of the fixing roller, the drive gear, and the tooth-missing gear when viewed from the axial direction, and (b) shows the drive gear and the first tooth-missing gear from (a). FIG. 4C is a side view after removing all the components, and FIG. 6C is a side view when all the members other than the rollers are removed from FIG. （ａ）−（ｃ）は、カムが１回転する期間の前半における第１欠歯ギアの姿勢の変化を回転角の順に示す模式的な平面図であり、（ｄ）−（ｆ）は、第１欠歯ギアが（ａ）−（ｃ）の各姿勢を取るときにおける第２欠歯ギアの姿勢を示す模式的な平面図である。（ｇ）は、欠歯ギアが（ｂ）、（ｅ）の示す停止姿勢を維持するときの定着ローラーと均熱ローラーとを模式的に示す側面図である。(A)-(c) is a typical top view which shows the change of the attitude|position of the 1st partly tooth-missing gear in order of rotation angle in the first half of the period which a cam rotates once, (d)-(f) is, It is a typical top view which shows the attitude|position of a 2nd tooth-missing gear when the 1st tooth-missing gear takes each attitude|position of (a)-(c). (G) is a side view schematically showing the fixing roller and the heat equalizing roller when the tooth-missing gear maintains the stopped posture shown in (b) and (e). （ａ）−（ｃ）は、カムが１回転する期間の後半における第１欠歯ギアの姿勢の変化を回転角の順に示す模式的な平面図であり、（ｄ）−（ｆ）は、第１欠歯ギアが（ａ）−（ｃ）の各姿勢を取るときにおける第２欠歯ギアの姿勢を示す模式的な平面図である。（ｇ）は、欠歯ギアが（ｂ）、（ｅ）の示す停止姿勢を維持するときの定着ローラーと均熱ローラーとを模式的に示す側面図である。(A)-(c) is a typical top view which shows the change of the attitude|position of the 1st partly tooth-missing gear in order of rotation angle in the latter half of the period which a cam rotates once, (d)-(f) is, It is a typical top view which shows the attitude|position of a 2nd tooth-missing gear when the 1st tooth-missing gear takes each attitude|position of (a)-(c). (G) is a side view schematically showing the fixing roller and the heat equalizing roller when the tooth-missing gear maintains the stopped posture shown in (b) and (e). （ａ）、（ｂ）は、第１欠歯ギアがコイルバネの復元力を受けて回転し始めた際の第１欠歯ギアと駆動ギアとの咬合部分を示す模式的な拡大図である。（ｃ）は、第１欠歯ギアの伝達部材が第２欠歯ギアを押すことにより２枚の欠歯ギアが一体的に回転する際の欠歯ギアと駆動ギアとの咬合部分を示す模式的な拡大図である。(A), (b) is a typical enlarged view which shows the occlusal part of a 1st tooth-missing gear and a drive gear, when a 1st tooth-missing gear receives the restoring force of a coil spring and starts to rotate. (C) is a schematic diagram showing an engagement portion between a tooth-missing gear and a drive gear when the two tooth-missing gears are integrally rotated by the transmission member of the first tooth-missing gear pushing the second tooth-missing gear FIG.

以下、本発明の実施形態について、図面を参照しながら説明する。
［画像形成装置の外観］
図１の（ａ）は、本発明の実施形態による画像形成装置１００の外観を示す斜視図である。この画像形成装置１００は電子写真方式のカラープリンター、すなわちカラーレーザープリンターである。プリンター１００の筐体の上面には排紙トレイ４１が設けられ、その奥に開いた排紙口４２から排紙されたシートを収容する。排紙トレイ４１の前方には操作パネル５１が取り付けられている。操作パネル５１には、各種の機械的な押しボタンに加え、タッチパネル内蔵のディスプレイが配置されている。ディスプレイは、操作画面、各種情報の入力画面等のグラフィックスユーザーインターフェース（ＧＵＩ）画面を表示する。タッチパネルは、アイコン、仮想ボタン、メニュー、ツールバー等、ＧＵＩ画面の含むガジェットを通してユーザーの入力操作を受け付ける。プリンター１００の底部には給紙カセット１１が引き出し可能に取り付けられ、その中にシートの束が収容される。「シート」とは、紙製もしくは樹脂製の薄膜状もしくは薄板状の材料、物品、または印刷物をいう。給紙カセット１１に収容可能なシートの種類すなわち紙種は、普通紙、上質紙、カラー用紙、または塗工紙であり、サイズは、Ａ３、Ａ４、Ａ５、またはＢ４である。さらに、シートの姿勢は縦置きと横置きとのいずれにも設定可能である。 Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[Appearance of image forming apparatus]
FIG. 1A is a perspective view showing the outer appearance of the image forming apparatus 100 according to the embodiment of the present invention. The image forming apparatus 100 is an electrophotographic color printer, that is, a color laser printer. A paper discharge tray 41 is provided on the upper surface of the housing of the printer 100, and accommodates a sheet discharged from a paper discharge port 42 opened at the back. An operation panel 51 is attached to the front of the paper discharge tray 41. On the operation panel 51, in addition to various mechanical push buttons, a display with a built-in touch panel is arranged. The display displays a graphics user interface (GUI) screen such as an operation screen and an input screen for various information. The touch panel accepts a user's input operation through a gadget including a GUI screen such as an icon, a virtual button, a menu, and a toolbar. A paper feed cassette 11 is detachably attached to the bottom of the printer 100, and a bundle of sheets is accommodated in the paper feed cassette 11. The “sheet” refers to a thin-film or thin-plate material, article, or printed matter made of paper or resin. The types of sheets that can be accommodated in the paper feed cassette 11, that is, the paper types, are plain paper, high-quality paper, color paper, or coated paper, and the size is A3, A4, A5, or B4. Further, the posture of the seat can be set to be either vertical or horizontal.

［画像形成装置の内部構造］
図１の（ｂ）は、図１の（ａ）の示す直線Ｉｂ−Ｉｂに沿ったプリンター１００の模式的な断面図である。この図が示すようにプリンター１００は、給送部１０、作像部２０、定着部３０、および排紙部４０を含む。
給送部１０は、給紙ローラー１２を利用して給紙カセット１１からシートＳＨ１を１枚ずつ繰り出す。このシートＳＨ１が給紙カセット１１から到達する時点ではタイミングローラー１３は停止しているので、そのシートＳＨ１はその先端をタイミングローラー１３に接触させた状態で一旦停止する。その到着時点から所定時間が経過した時点で、給送部１０はタイミングローラー１３に回転を開始させる。これにより、停止していたシートＳＨ１が作像部２０へ送出される。 [Internal structure of image forming apparatus]
1B is a schematic cross-sectional view of the printer 100 taken along the line Ib-Ib shown in FIG. As shown in this figure, the printer 100 includes a feeding unit 10, an image forming unit 20, a fixing unit 30, and a paper discharge unit 40.
The feeding unit 10 uses the sheet feeding roller 12 to feed out the sheets SH1 from the sheet feeding cassette 11 one by one. Since the timing roller 13 is stopped at the time when the sheet SH1 arrives from the sheet feeding cassette 11, the sheet SH1 is temporarily stopped with its leading end in contact with the timing roller 13. When a predetermined time has passed from the arrival time, the feeding unit 10 causes the timing roller 13 to start rotating. As a result, the stopped sheet SH1 is sent to the image forming unit 20.

作像部２０は、たとえばタンデム型の印刷エンジンであり、給送部１０から送られたシートＳＨ２にカラートナー像を形成する。具体的には、４つの感光体（ＰＣ）ユニット２０Ｙ、２０Ｍ、２０Ｃ、２０Ｋのそれぞれがまず感光体（ＰＣ）ドラム２１Ｙ、２１Ｍ、２１Ｃ、２１Ｋの表面を帯電させ、その帯電部分を露光部２２からの光に曝す。これらの光は、画像データの示すイエロー（Ｙ）、マゼンタ（Ｍ）、シアン（Ｃ）、ブラック（Ｋ）の階調値分布に従って変調されているので、ＰＣドラム２１Ｙ、…の各表面には、各色の階調値分布に対応する静電潜像が形成される。ＰＣユニット２０Ｙ、…は次に静電潜像を、Ｙ、Ｍ、Ｃ、Ｋのトナーで現像する。これら４色のトナー像は、１次転写ローラー２３Ｙ、２３Ｍ、２３Ｃ、２３ＫとＰＣドラム２１Ｙ、…との間の電界により、ＰＣドラム２１Ｙ、…の表面から順番に中間転写ベルト２４の表面上の同じ位置へ転写される。こうしてその位置に１つのカラートナー像が構成される。このカラートナー像はその後、中間転写ベルト２４の駆動プーリー２４Ｒと２次転写ローラー２５との間のニップを通過する際、両者２４Ｒ、２５の間の電界により、同じニップへ同時に通紙されたシートＳＨ２の表面へ転写される。その後、このシートＳＨ２は駆動プーリー２４Ｒの回転により、定着部３０へ送出される。 The image forming unit 20 is, for example, a tandem type print engine, and forms a color toner image on the sheet SH2 sent from the feeding unit 10. Specifically, each of the four photoconductor (PC) units 20Y, 20M, 20C, and 20K first charges the surface of the photoconductor (PC) drums 21Y, 21M, 21C, and 21K, and the charged portions thereof are exposed by the exposure unit 22. Exposed to light from. Since these lights are modulated according to the gradation value distribution of yellow (Y), magenta (M), cyan (C), and black (K) indicated by the image data, the respective surfaces of the PC drums 21Y,... , An electrostatic latent image corresponding to the gradation value distribution of each color is formed. Then, the PC units 20Y,... Develop the electrostatic latent image with Y, M, C, and K toners. These four color toner images are formed on the surface of the intermediate transfer belt 24 in order from the surface of the PC drums 21Y,... By the electric field between the primary transfer rollers 23Y, 23M, 23C, 23K and the PC drums 21Y,. Transferred to the same position. Thus, one color toner image is formed at that position. When the color toner image then passes through the nip between the drive pulley 24R of the intermediate transfer belt 24 and the secondary transfer roller 25, the sheet simultaneously passed to the same nip by the electric field between the two 24R and 25R. Transferred to the surface of SH2. Then, the sheet SH2 is sent to the fixing unit 30 by the rotation of the drive pulley 24R.

定着部３０は、作像部２０から送出されたシートＳＨ３にトナー像を熱定着させる。具体的には、定着部３０はこのシートＳＨ３を定着ローラー３１と加圧ローラー３２との間のニップへ通紙させる。このとき、定着ローラー３１はシートＳＨ３の表面へ内蔵のヒーターの熱を加え、加圧ローラー３２はシートＳＨ３の加熱部分に対して圧力を加えて定着ローラー３１へ押し付ける。定着ローラー３１からの熱と加圧ローラー３２からの圧力とにより、トナーがシートＳＨ３の表面上に溶着する。その後、定着ローラー３１と加圧ローラー３２とはこのシートＳＨ３を排紙部４０へ送出する。 The fixing unit 30 heat-fixes the toner image on the sheet SH3 sent from the image forming unit 20. Specifically, the fixing unit 30 causes the sheet SH3 to pass through the nip between the fixing roller 31 and the pressure roller 32. At this time, the fixing roller 31 applies heat from the built-in heater to the surface of the sheet SH3, and the pressure roller 32 applies pressure to the heated portion of the sheet SH3 and presses it against the fixing roller 31. Due to the heat from the fixing roller 31 and the pressure from the pressure roller 32, the toner is fused on the surface of the sheet SH3. After that, the fixing roller 31 and the pressure roller 32 send out the sheet SH3 to the paper output unit 40.

排紙部４０は、定着部３０から送出されたシートＳＨ３を排紙トレイ４１へ搬送する。具体的には、そのシートＳＨ３の先端が定着部３０から排紙ローラー４３の間のニップまで到達したとき、この先端を排紙ローラー４３が排紙口４２へ引き込む。これにより、そのシートＳＨ３は先端から順に排紙口４２を通過し、排紙トレイ４１に積載される。
［定着ローラーの駆動機構］
図２の（ａ）は、定着ローラー３１、均熱ローラー３３、およびクリーニングローラー３４とそれらの駆動機構３００との模式的な斜視図である。図１の（ｂ）と図２の（ａ）とが示すように、定着部３０は更に、均熱ローラー３３とクリーニングローラー３４とを含む。これらのローラー３３、３４は定着ローラー３１と回転軸が互いに平行に配置されている。定着ローラー３１の回転軸はフレーム３１Ｆにより直接、回転可能に支持され、他のローラー３３、３４の回転軸は、支持部材３３Ａ、３４Ａを通してフレーム３１Ｆにより間接的に、回転可能に支持されている。フレーム３１Ｆと支持部材３３Ａ、３４Ａとは硬質樹脂製または金属製である。フレーム３１Ｆはその下面がプリンター１００の筐体に固定される。 The paper discharge unit 40 conveys the sheet SH3 sent from the fixing unit 30 to the paper discharge tray 41. Specifically, when the leading edge of the sheet SH3 reaches the nip between the fixing unit 30 and the sheet discharging roller 43, the sheet discharging roller 43 pulls the leading edge into the sheet discharging port 42. As a result, the sheet SH3 sequentially passes through the sheet discharge port 42 from the leading edge and is stacked on the sheet discharge tray 41.
[Fixing roller drive mechanism]
FIG. 2A is a schematic perspective view of the fixing roller 31, the soaking roller 33, the cleaning roller 34, and their drive mechanism 300. As shown in FIGS. 1B and 2A, the fixing unit 30 further includes a soaking roller 33 and a cleaning roller 34. The rollers 33 and 34 are arranged such that the rotation axes of the fixing roller 31 and the fixing roller 31 are parallel to each other. The rotation shaft of the fixing roller 31 is directly and rotatably supported by the frame 31F, and the rotation shafts of the other rollers 33 and 34 are indirectly and rotatably supported by the frame 31F through the support members 33A and 34A. The frame 31F and the support members 33A and 34A are made of hard resin or metal. The lower surface of the frame 31F is fixed to the housing of the printer 100.

定着ローラー３１は、芯金、弾性体層、および離型層を含む（図２の（ａ）は示していない）。芯金はたとえば直径数十ｍｍの円筒部材であり、主に、アルミニウム、鉄等の金属から成る。弾性体層は、芯金の外側を覆う、主にシリコーンゴム等、高弾性の耐熱性樹脂から成る層である。離型層は、弾性体層の外側を覆うフッ素樹脂等の薄膜であり、定着ローラー３１の外周面を形成している。離型層は、定着ローラー３１による加熱で溶融したトナーがシートの表面から定着ローラー３１の外周面へ転移する現象（オフセット現象）を防止する。 The fixing roller 31 includes a core metal, an elastic layer, and a release layer ((a) of FIG. 2 is not shown). The core metal is, for example, a cylindrical member having a diameter of several tens of mm, and is mainly made of metal such as aluminum and iron. The elastic layer is a layer that covers the outside of the cored bar and is mainly made of a highly elastic heat-resistant resin such as silicone rubber. The release layer is a thin film of fluororesin or the like that covers the outside of the elastic layer, and forms the outer peripheral surface of the fixing roller 31. The release layer prevents a phenomenon (offset phenomenon) in which the toner melted by heating by the fixing roller 31 is transferred from the surface of the sheet to the outer peripheral surface of the fixing roller 31.

均熱ローラー３３は、アルミニウム、銅等、熱伝導性の高い金属製の円筒部材であり、定着ローラー３１の外周面に離間可能に接触し、定着ローラー３１の回転に伴って従動回転する。定着対象のシートの幅、すなわち定着ローラー３１の軸方向におけるそのシートの長さが定着ローラー３１の加熱部分の長さよりも短い場合（たとえばＡ４サイズのプリンターでは、Ｂ５、２Ｌ版、ハガキ等。）、均熱ローラー３３は定着ローラー３１の外周面に押し付けられる。これにより均熱ローラー３３は、シートによる局所的な熱の吸収にかかわらず、定着ローラー３１の表面温度分布を、特に軸方向において実質的に均一に保つ。一方、定着対象のシートの幅が定着ローラー３１の加熱部分の長さと実質的に等しい場合、均熱ローラー３３は定着ローラー３１の外周面から離される。これにより定着ローラー３１から均熱ローラー３３への熱の逃げが防止される。 The soaking roller 33 is a cylindrical member made of a metal having high heat conductivity such as aluminum or copper, contacts the outer peripheral surface of the fixing roller 31 in a separable manner, and is rotated by rotation of the fixing roller 31. When the width of the sheet to be fixed, that is, the length of the sheet in the axial direction of the fixing roller 31 is shorter than the length of the heated portion of the fixing roller 31 (for example, for an A4 size printer, B5, 2L plate, postcard, etc.). The soaking roller 33 is pressed against the outer peripheral surface of the fixing roller 31. As a result, the soaking roller 33 keeps the surface temperature distribution of the fixing roller 31 substantially uniform, particularly in the axial direction, regardless of the local heat absorption by the sheet. On the other hand, when the width of the sheet to be fixed is substantially equal to the length of the heated portion of the fixing roller 31, the soaking roller 33 is separated from the outer peripheral surface of the fixing roller 31. This prevents heat from escaping from the fixing roller 31 to the soaking roller 33.

クリーニングローラー３４は、外周面が耐熱性の不織布で覆われた円筒部材であり、均熱ローラー３３の外周面に接触している。クリーニングローラー３４は駆動系統３００から回転力を受けて、均熱ローラー３３とは独立に回転する。この回転力を利用してクリーニングローラー３４は、自身の外周面で均熱ローラー３３の外周面から、紙粉、トナー等の異物を擦り取る。 The cleaning roller 34 is a cylindrical member whose outer peripheral surface is covered with a heat-resistant nonwoven fabric, and is in contact with the outer peripheral surface of the soaking roller 33. The cleaning roller 34 receives a rotational force from the drive system 300 and rotates independently of the soaking roller 33. Utilizing this rotational force, the cleaning roller 34 scrapes off foreign matter such as paper powder and toner from the outer peripheral surface of the heat equalizing roller 33 by its outer peripheral surface.

図２の（ｂ）は、（ａ）が示す駆動機構３００の周辺の外観を示す拡大斜視図である。この図が示すように駆動機構３００はギア列２０１、２０２、２０３、２０４、２０５、２０６、２０７を含む。各ギア２０１、…、２０７は硬質樹脂製または金属製の平歯車である。ギア列の先頭（図２の（ｂ）の中では最も下）に位置するギア２０１は、プリンター１００の筐体に固定された駆動モーター、たとえば直流ブラシレス（ＢＬＤＣ）モーター（図２の（ｂ）は示していない。）のシャフトに同軸に固定され、そのシャフトと共に回転する。ギア列のうち２番目以降のギア２０２−２０７は、フレーム３１Ｆに支持されたシャフトにより、そのまわりを回転可能に支持されている。２番目のギア２０２は、先頭のギア２０１と３番目のギア２０３とに噛み合い、先頭のギア２０１を通して駆動モーターから受けた回転力を３番目のギア２０３へ伝達する。３番目のギア２０３は、定着ローラー３１のシャフト３１Ｓに同軸に固定され、先頭のギア２０１と２番目のギア２０２とを通して駆動モーターから受けた回転力を定着ローラー３１に伝える。４番目のギア２０４は３番目のギア２０３と噛み合い、５番目のギア２０５は４番目のギア２０４と噛み合う。６番目のギア２０６は５番目のギア２０５に同軸に固定され、そのギア２０５と同じ角速度で回転する。最後尾のギア２０７はクリーニングローラー３４のシャフト３４Ｓに同軸に固定され、６番目のギア２０６と噛み合っている。こうして、ギア列の後半の４枚２０４−２０７は、前半の３枚２０１−２０３を通して駆動モーターが定着ローラー３１へ与える回転力の一部を、クリーニングローラー３４へ分け与える。駆動モーターが回転を持続させる間、定着ローラー３１とクリーニングローラー３４とは定常的に回転し続ける。 2B is an enlarged perspective view showing the external appearance of the periphery of the drive mechanism 300 shown in FIG. As this figure shows, the drive mechanism 300 includes a gear train 201, 202, 203, 204, 205, 206, 207. Each of the gears 201,..., 207 is a spur gear made of hard resin or metal. The gear 201 located at the head of the gear train (the lowest in FIG. 2B) is a drive motor fixed to the housing of the printer 100, for example, a direct current brushless (BLDC) motor (FIG. 2B). (Not shown) is coaxially fixed to the shaft and rotates with the shaft. The second and subsequent gears 202 to 207 of the gear train are rotatably supported by shafts supported by the frame 31F. The second gear 202 meshes with the first gear 201 and the third gear 203, and transmits the rotational force received from the drive motor through the first gear 201 to the third gear 203. The third gear 203 is coaxially fixed to the shaft 31S of the fixing roller 31, and transmits the rotational force received from the drive motor to the fixing roller 31 through the first gear 201 and the second gear 202. The fourth gear 204 meshes with the third gear 203, and the fifth gear 205 meshes with the fourth gear 204. The sixth gear 206 is coaxially fixed to the fifth gear 205 and rotates at the same angular velocity as the gear 205. The rearmost gear 207 is coaxially fixed to the shaft 34S of the cleaning roller 34, and meshes with the sixth gear 206. In this way, the four sheets 204-207 in the latter half of the gear train share a part of the rotational force given to the fixing roller 31 by the drive motor through the three sheets 201-203 in the first half to the cleaning roller 34. The fixing roller 31 and the cleaning roller 34 constantly rotate while the drive motor continues to rotate.

［均熱ローラーの離間機構］
図２の（ｂ）が示すように駆動機構３００は更に、駆動ギア３１０、第１欠歯ギア３２１、第２欠歯ギア３２２、および初動部材３３１−３３４を含む。これらは協働して均熱ローラー３３を定着ローラー３１から離間させ、または再び定着ローラー３１に接触させる。駆動ギア３１０は、クリーニングローラー３４のシャフト３４Ｓに同軸に固定された硬質樹脂製または金属製の平歯車であり、クリーニングローラー３４と同じ角速度で回転する。第１欠歯ギア３２１と第２欠歯ギア３２２とは硬質樹脂製または金属製の平歯車であり、外周の一部から歯が除去されている。欠歯ギア３２１、３２２は歯先円が同じサイズであり、互いに同軸に重ね合わされ、均熱ローラー３３のシャフトにより同軸に、そのまわりを均熱ローラー３３とは独立に回転可能であるように支持されている。各欠歯ギア３２１、３２２は、有歯部が駆動ギア３１０と噛み合い可能である。２枚重ねの欠歯ギア３２１、３２２全体の歯幅が駆動ギア３１０の歯幅とほぼ等しい。初動部材３３１−３３４は定着ローラー３１のフレーム３１Ｆの上部に設置され、欠歯ギア３２１、３２２に覆い被さるように下方へ伸びている。 [Soaking mechanism for soaking rollers]
As shown in FIG. 2B, the drive mechanism 300 further includes a drive gear 310, a first tooth-chipped gear 321, a second tooth-chipped gear 322, and initial moving members 331-334. These cooperate to separate the soaking roller 33 from the fixing roller 31 or to bring the fixing roller 31 into contact again. The drive gear 310 is a hard resin or metal spur gear that is coaxially fixed to the shaft 34S of the cleaning roller 34, and rotates at the same angular velocity as the cleaning roller 34. The first tooth-chipped gear 321 and the second tooth-chipped gear 322 are spur gears made of hard resin or metal, and teeth are removed from a part of the outer circumference. The tooth-chipped gears 321 and 322 have the same tip circles and are superposed coaxially with each other, and are supported coaxially by the shaft of the heat equalizing roller 33 so as to be rotatable around the shaft independently of the heat equalizing roller 33. Has been done. The toothless parts of the toothless gears 321 and 322 can mesh with the drive gear 310. The tooth widths of the two overlapping toothless gears 321 and 322 are substantially equal to the tooth width of the drive gear 310. The initial moving members 331-334 are installed above the frame 31F of the fixing roller 31 and extend downward so as to cover the toothless gears 321 and 322.

−初動部材−
図３の（ａ）は、定着ローラー３１のフレーム３１Ｆからギア列２０１−２０７を除去したときの外観を示す拡大斜視図であり、（ｂ）は、（ａ）の示す構成から更に初動部材の一部３３１を除去したときの外観を示す斜視図である。これらの図が示すように、初動部材は、スライダー３３１、保持部材３３２、ソレノイド３３３、および緩衝部材３３４を含む。スライダー３３１は実質的に板状の部材であり、均熱ローラー３３のシャフトに対して垂直に拡がるフレーム３１Ｆの側面に板面を接触させた状態でその側面を上下方向に摺動可能である。保持部材３３２は棒状部材であり、フレーム３１Ｆの側面の貫通穴３１Ｈを通してその側面の法線方向に伸びている。保持部材３３２の基端はスライダー３３１の摺動面に固定され、先端は、均熱ローラー３３のシャフトに支持された第１欠歯ギア３２１の表面に接している。保持部材３３２はスライダー３３１の摺動に伴い、フレーム３１Ｆの側面に対して垂直な姿勢を保ったまま、上下方向に平行移動する。ソレノイド３３３はスライダー３３１の上端に固定され、プランジャー３３Ｐの先端がフレーム３１Ｆの上面を押すように設置されている。緩衝部材３３４は円柱形状のエラストマーであり、ソレノイド３３３の下方に位置するフレーム３１Ｆの側面の上端から下へ伸びる切り込み３１Ｃの中に配置されている。緩衝部材３３４の下端はその切り込み３１Ｃの下面に固定され、上端はフレーム３１Ｆの上面よりも高い位置まで伸びている。ソレノイド３３３のオフ時、ソレノイド３３３に内蔵のバネの弾性力によりプランジャー３３Ｐはその先端でフレーム３１Ｆの上面を押す。これにより、ソレノイド３３３とスライダー３３１との全体がフレーム３１Ｆに対して持ち上がる。図３はこの状態を示す。ソレノイド３３３がオンするとプランジャー３３Ｐがソレノイド３３３の内部に引き込まれるので、ソレノイド３３３とスライダー３３１との全体が自重で落下する。このとき、ソレノイド３３３の下面が緩衝部材３３４の上端に受け止められるので、緩衝部材３３４の弾性により、フレーム３１Ｆの上面から受ける衝撃が緩和される。図３の（ａ）が示す一点鎖線はこの状態におけるスライダー３３１の位置を示す。こうして、ソレノイド３３３のオンオフに合わせてスライダー３３１が上下に変位する。 -Initial member-
FIG. 3A is an enlarged perspective view showing an external appearance when the gear trains 201-207 are removed from the frame 31F of the fixing roller 31, and FIG. 3B is a diagram showing a structure of FIG. It is a perspective view which shows the external appearance when a part 331 is removed. As shown in these figures, the initial moving member includes a slider 331, a holding member 332, a solenoid 333, and a cushioning member 334. The slider 331 is a substantially plate-shaped member, and can slide in the vertical direction on the side surface of the frame 31F that extends vertically to the shaft of the heat equalizing roller 33 while the plate surface is in contact with the side surface. The holding member 332 is a rod-shaped member, and extends through the through hole 31H on the side surface of the frame 31F in the normal direction to the side surface. The base end of the holding member 332 is fixed to the sliding surface of the slider 331, and the front end is in contact with the surface of the first tooth-chipped gear 321 supported by the shaft of the heat equalizing roller 33. As the slider 331 slides, the holding member 332 moves in parallel in the vertical direction while maintaining a posture perpendicular to the side surface of the frame 31F. The solenoid 333 is fixed to the upper end of the slider 331, and is installed so that the tip of the plunger 33P pushes the upper surface of the frame 31F. The cushioning member 334 is a columnar elastomer, and is disposed in a notch 31C extending downward from the upper end of the side surface of the frame 31F located below the solenoid 333. The lower end of the buffer member 334 is fixed to the lower surface of the cut 31C, and the upper end extends to a position higher than the upper surface of the frame 31F. When the solenoid 333 is off, the elastic force of the spring built into the solenoid 333 causes the plunger 33P to push the upper surface of the frame 31F with its tip. As a result, the solenoid 333 and the slider 331 are entirely lifted with respect to the frame 31F. FIG. 3 shows this state. When the solenoid 333 is turned on, the plunger 33P is drawn into the solenoid 333, so that the solenoid 333 and the slider 331 are entirely dropped by their own weight. At this time, since the lower surface of the solenoid 333 is received by the upper end of the cushioning member 334, the elasticity of the cushioning member 334 reduces the impact received from the upper surface of the frame 31F. The dashed-dotted line shown in FIG. 3A indicates the position of the slider 331 in this state. In this way, the slider 331 is vertically displaced according to the on/off state of the solenoid 333.

ソレノイド３３３のオンオフはプリンター１００の制御部が、たとえば印刷対象のシートのサイズに応じて切り換える。具体的には、シートの幅に対する閾値が、定着ローラー３１の加熱部分の長さ以下の値に予め設定される。ある印刷ジョブが対象とするシートの幅が閾値よりも短い場合、制御部はこのジョブ処理を開始する前にソレノイド３３３をオンまたはオフさせて、均熱ローラー３３を定着ローラー３１に接触させる。次の印刷ジョブでは対象のシートの幅が閾値以上である場合、制御部は次のジョブ処理を開始する前にソレノイド３３３のオンオフを切り換えて、均熱ローラー３３を定着ローラー３１から離間させる。 The control unit of the printer 100 switches ON/OFF of the solenoid 333 according to, for example, the size of the sheet to be printed. Specifically, the threshold value for the width of the sheet is preset to a value equal to or less than the length of the heated portion of the fixing roller 31. When the width of the target sheet of a certain print job is shorter than the threshold value, the control unit turns on or off the solenoid 333 before the job processing is started to bring the soaking roller 33 into contact with the fixing roller 31. In the next print job, when the width of the target sheet is equal to or larger than the threshold value, the control unit switches the solenoid 333 on and off before starting the next job processing, and separates the heat equalizing roller 33 from the fixing roller 31.

−欠歯ギア−
図４の（ａ）は、図３の（ｂ）の示す構成から初動部材３３１−３３４を除去したときの外観を示す拡大斜視図である。定着ローラー３１は、図２の示すギア列の前半２０１−２０３を通して駆動モーターから受けた回転力により、シャフト３１Ｓのまわりを反時計方向ＣＣＷに回転する。クリーニングローラー３４のシャフト３４Ｓは支持部材３４Ａの貫通穴に回転可能に挿入され、その支持部材３４Ａは上端がコイルバネ３４Ｂでフレーム３１Ｆの上面（図４の（ａ）は示していない。）に接続されている。このシャフト３４Ｓのまわりをクリーニングローラー３４は、図２の示すギア列の後半２０４−２０７を通して定着ローラー３１から分け与えられた回転力により、時計方向ＣＷに回転する。この回転に合わせて駆動ギア３１０も時計方向ＣＷに回転する。均熱ローラー３３のシャフト３３Ｓは支持部材３３Ａの貫通穴に回転可能に挿入され、その支持部材３３Ａは上端がコイルバネ３３Ｂでフレーム３１Ｆの上面（図４の（ａ）は示していない。）に接続されている。このシャフト３３Ｓのまわりを欠歯ギア３２１、３２２は、駆動ギア３１０に対して回転姿勢にある間、駆動ギア３１０からの回転力により反時計方向ＣＣＷに回転する。 -Toothless gear-
FIG. 4A is an enlarged perspective view showing the appearance when the initial moving members 331-334 are removed from the configuration shown in FIG. 3B. The fixing roller 31 rotates in the counterclockwise direction CCW around the shaft 31S by the rotational force received from the drive motor through the first half 201-203 of the gear train shown in FIG. The shaft 34S of the cleaning roller 34 is rotatably inserted into the through hole of the supporting member 34A, and the upper end of the supporting member 34A is connected to the upper surface (not shown in FIG. 4A) of the frame 31F by the coil spring 34B. ing. The cleaning roller 34 rotates in the clockwise direction CW around the shaft 34S by the rotational force given from the fixing roller 31 through the latter half 204-207 of the gear train shown in FIG. The drive gear 310 also rotates clockwise CW in accordance with this rotation. The shaft 33S of the heat equalizing roller 33 is rotatably inserted into the through hole of the supporting member 33A, and the upper end of the supporting member 33A is connected to the upper surface of the frame 31F (not shown in FIG. 4A) by the coil spring 33B. Has been done. The tooth-chipped gears 321 and 322 rotate in the counterclockwise direction CCW by the rotational force from the drive gear 310 while the toothless gears 321 and 322 are in the rotation posture with respect to the drive gear 310 around the shaft 33S.

図４の（ｂ）は、均熱ローラー３３と欠歯ギア３２１、３２２との接続部の分解斜視図であり、図４の（ｃ）は、図４の（ａ）の示す直線ｃ−ｃに沿ったその接続部の断面図である。均熱ローラー３３の端部では、円筒形状の軸受３３Ｌにシャフト３３Ｓが同軸に挿入され、この軸受３３Ｌがシャフト３３Ｓと支持部材３３Ａとの隙間を埋める。軸受３３Ｌは、断熱性が高く、かつ熱膨張率が低い樹脂製である。均熱ローラー３３の軸方向においてこの軸受３３Ｌよりも外側には、まず第２欠歯ギア３２２が配置され、その外側に第１欠歯ギア３２１が配置される。第２欠歯ギア３２２の外側の表面には中心部からスリーブ３２Ｖが突出している。スリーブ３２Ｖの中に均熱ローラー３３のシャフト３３Ｓが挿入され、スリーブ３２Ｖは第１欠歯ギア３２１の中心の穴に挿入される。これにより、シャフト３３Ｓに直に接触するのは第２欠歯ギア３２２だけである。 4B is an exploded perspective view of a connection portion between the soaking roller 33 and the toothless gears 321 and 322, and FIG. 4C is a straight line cc shown in FIG. FIG. 5 is a cross-sectional view of the connection portion along the line. At the end of the soaking roller 33, a shaft 33S is coaxially inserted into a cylindrical bearing 33L, and this bearing 33L fills the gap between the shaft 33S and the support member 33A. The bearing 33L is made of resin having a high heat insulating property and a low coefficient of thermal expansion. A second partly tooth-missing gear 322 is arranged outside the bearing 33L in the axial direction of the heat equalizing roller 33, and a first partly-missing gear 321 is arranged outside thereof. A sleeve 32V projects from the center of the outer surface of the second partly tooth-missing gear 322. The shaft 33S of the heat equalizing roller 33 is inserted into the sleeve 32V, and the sleeve 32V is inserted into the central hole of the first tooth-missing gear 321. As a result, only the second partly tooth-missing gear 322 directly contacts the shaft 33S.

図４の（ｃ）が示すように、第１欠歯ギア３２１と第２欠歯ギア３２２との隙間ＧＰ１にも、均熱ローラー３３のシャフト３３Ｓと第２欠歯ギア３２２との隙間ＧＰ２にも、十分に大きなガタが設計されている。これによりいずれの隙間ＧＰ１、ＧＰ２にも、シャフト３３Ｓと欠歯ギア３２１、３２２との熱膨張に起因する詰まりが生じない。実際、定着ローラー３１の表面温度は一般に、２００℃前後の高い値に維持される。したがって、定着ローラー３１と直に接触する均熱ローラー３３を始め、そのシャフト３３Ｓ、および欠歯ギア３２１、３２２も、定着ローラー３１からの熱を受けて同程度の高温になり得る。このような高温に長時間曝された結果、各部材３３Ｓ、３２１、３２２の熱膨張が許容上限に達しても、上記のガタにより、それらの隙間ＧＰ１、ＧＰ２には詰まりが生じない。 As shown in (c) of FIG. 4, in the gap GP1 between the first tooth-chipped gear 321 and the second tooth-chipped gear 322 as well as in the gap GP2 between the shaft 33S of the heat equalizing roller 33 and the second tooth-chipped gear 322. Even, the play is large enough. As a result, neither gap GP1 nor GP2 is clogged due to thermal expansion between the shaft 33S and the toothless gears 321 and 322. In fact, the surface temperature of the fixing roller 31 is generally maintained at a high value around 200°C. Therefore, the heat equalizing roller 33, which is in direct contact with the fixing roller 31, the shaft 33S thereof, and the toothless gears 321 and 322 can also reach the same high temperature due to the heat from the fixing roller 31. As a result of being exposed to such a high temperature for a long time, even if the thermal expansion of the members 33S, 321, 322 reaches the allowable upper limit, the gaps GP1 and GP2 do not become clogged due to the play described above.

−第１欠歯ギアの構造−
図５の（ａ）は、第１欠歯ギア３２１の表面（回転軸方向において均熱ローラー３３とは反対側に位置する面）３２Ｏを示す平面図であり、（ｂ）は、第１欠歯ギア３２１の裏面（回転軸方向において均熱ローラー３３と同じ側に位置する面）３２Ｕを示す平面図であり、（ｃ）は第１欠歯ギア３２１の側面図である。 -Structure of the first partly tooth-missing gear-
FIG. 5A is a plan view showing a surface (a surface located on the opposite side of the heat equalizing roller 33 in the rotation axis direction) 32O of the first tooth-chipped gear 321, and FIG. It is a top view which shows the back surface (surface located on the same side as the heat equalizing roller 33 in the rotation axis direction) 32U of the tooth gear 321, and (c) is a side view of the first tooth-chipped gear 321.

第１欠歯ギア３２１は外周に有歯部４１Ｔと欠歯部４１Ｍとを２つずつ含む。第１欠歯ギア３２１の回転方向（図５の（ａ）では反時計方向ＣＣＷ、（ｂ）では時計方向ＣＷ）において有歯部４１Ｔの先頭に位置する歯４１１は、第１欠歯ギア３２１の中心に対して互いに対称に位置する。
第１欠歯ギア３２１の表面３２Ｏには半円形状の外溝４１Ｇと内溝４１Ｈとが刻まれている。各溝４１Ｇ、４１Ｈは第１欠歯ギア３２１と同心であり、その中心に対して互いに対称的に配置されている。外溝４１Ｇが描く半円は、内溝４１Ｈが描く半円よりも半径が大きい。各溝４１Ｇ、４１Ｈの周方向における端は第１欠歯ギア３２１の回転方向における有歯部４１Ｔの後端とほぼ同じ半径方向に位置し、互いに接続されている。回転方向における各溝４１Ｇ、４１Ｈの後端は、半径方向に伸びる壁４１Ｗ、４１Ｘで仕切られている。これらの溝４１Ｇ、４１Ｈの中に保持部材３３２の先端３２Ｔが挿入される。 The first toothless gear 321 includes two toothed portions 41T and two toothless portions 41M on the outer circumference. The tooth 411 located at the head of the toothed portion 41T in the rotation direction of the first toothless gear 321 (counterclockwise CCW in FIG. 5A, clockwise CW in FIG. 5B) is the first toothless gear 321. They are located symmetrically with respect to the center of.
A semicircular outer groove 41G and an inner groove 41H are engraved on the surface 32O of the first tooth-missing gear 321. The grooves 41G and 41H are concentric with the first partly tooth-missing gear 321 and are arranged symmetrically with respect to the center thereof. The semicircle drawn by the outer groove 41G has a larger radius than the semicircle drawn by the inner groove 41H. The circumferential ends of the grooves 41G and 41H are located substantially in the same radial direction as the rear end of the toothed portion 41T in the rotational direction of the first tooth-missing gear 321, and are connected to each other. The rear ends of the grooves 41G and 41H in the rotation direction are partitioned by walls 41W and 41X extending in the radial direction. The tip 32T of the holding member 332 is inserted into these grooves 41G and 41H.

第１欠歯ギア３２１の裏面３２Ｕからは伝達部材３５０が突出している。伝達部材３５０は、第１欠歯ギア３２１の裏面３２Ｕに対して平行な断面が実質的に「コ」の字形をした柱状部材であり、第１欠歯ギア３２１と一体に成形されている。
−第２欠歯ギアの構造−
図６の（ａ）は、第２欠歯ギア３２２の表面（回転軸方向において均熱ローラー３３とは反対側に位置する面）を示す平面図であり、（ｂ）は、第１欠歯ギア３２１と第２欠歯ギア３３２との分解斜視図である。 The transmission member 350 projects from the back surface 32U of the first tooth-missing gear 321. The transmission member 350 is a columnar member having a substantially U-shaped cross section parallel to the back surface 32U of the first tooth-chipped gear 321, and is formed integrally with the first tooth-chipped gear 321.
-Structure of the second missing tooth gear-
FIG. 6A is a plan view showing the surface of the second tooth-missing gear 322 (the surface located on the opposite side of the heat equalizing roller 33 in the rotation axis direction), and FIG. 6B is the first tooth-missing gear. FIG. 9 is an exploded perspective view of a gear 321 and a second tooth-missing gear 332.

第２欠歯ギア３２２は外周に有歯部４２Ｔと欠歯部４２Ｍとを２つずつ含む。第２欠歯ギア３２２の回転方向（図６の（ａ）では反時計方向ＣＣＷ）において有歯部４２Ｔの先頭に位置する歯４２１は、第２欠歯ギア３２２の中心に対して互いに対称に位置する。
第２欠歯ギア３２２の表面は、第２欠歯ギア３２２と同心弧状の凹部４２Ｇを含む。第２欠歯ギア３２２の回転方向において凹部４２Ｇの後端は一方の有歯部４２Ｔの後端とほぼ同じ半径方向に位置する。凹部４２Ｇの周方向の各端は、半径方向に伸びる壁４２Ｗ、４２Ｘで仕切られている。凹部４２Ｇの中には、第１欠歯ギア３２１の裏面３２Ｕから突出した伝達部材３５０が挿入され、さらに、伝達部材３５０と凹部４２Ｇの先端の壁４２Ｘとの間にコイルバネ３３５が周方向に伸縮可能に挿入される。このバネ３３５は、後述のように、第１欠歯ギア３２１に対する初動部材の一部として機能する。 The second toothless gear 322 includes two toothed portions 42T and two toothless portions 42M on the outer circumference. In the rotation direction of the second partly tooth-missing gear 322 (counterclockwise CCW in FIG. 6A), the teeth 421 located at the head of the toothed part 42T are symmetrical with respect to the center of the second partly tooth-missing gear 322. To position.
The surface of the second tooth-chipped gear 322 includes a concave portion 42G that is concentric with the second tooth-chipped gear 322. The rear end of the concave portion 42G is located in substantially the same radial direction as the rear end of the one toothed portion 42T in the rotation direction of the second partly tooth-missing gear 322. The circumferential ends of the recess 42G are partitioned by walls 42W and 42X extending in the radial direction. A transmission member 350 protruding from the back surface 32U of the first tooth-missing gear 321 is inserted into the recess 42G, and a coil spring 335 is expanded and contracted in the circumferential direction between the transmission member 350 and the wall 42X at the tip of the recess 42G. Can be inserted. The spring 335 functions as a part of an initial moving member for the first toothless gear 321 as described later.

第２欠歯ギア３２２の裏面（回転軸方向において均熱ローラー３３と同じ側に位置する面）にはカム３６０が一体的に成形されている。カム３６０は、第２欠歯ギア３２２の表面に対して平行な板状部材であり、外周が睡蓮の葉のように、切れ込み３６１を含む滑らかな閉曲線を描いている。カム３６０は第２欠歯ギア３２２に対して偏心している。カム３６０の外周と第２欠歯ギア３２１の中心との間の距離は、一方の有歯部４２Ｔの先端とほぼ同じ半径方向（図６の（ｃ）では切れ込み３６１の近傍）において最大であり、他方の有歯部４２Ｔの先端とほぼ同じ半径方向（図では、切れ込み３６１の位置する方向に対してほぼ正反対の方向）において最小（切れ込み３６１を除く。）である。 A cam 360 is integrally formed on the back surface (the surface located on the same side as the heat equalizing roller 33 in the rotation axis direction) of the second tooth-missing gear 322. The cam 360 is a plate-shaped member that is parallel to the surface of the second partly tooth-missing gear 322, and its outer periphery forms a smooth closed curve including a notch 361 like a water lily leaf. The cam 360 is eccentric with respect to the second partly tooth-missing gear 322. The distance between the outer circumference of the cam 360 and the center of the second toothless gear 321 is maximum in the same radial direction as the tip of the one toothed portion 42T (in the vicinity of the notch 361 in FIG. 6C). In the same radial direction as the tip of the other toothed portion 42T (in the figure, the direction substantially opposite to the direction in which the notch 361 is located) is the minimum (excluding the notch 361).

−カム、均熱ローラー、定着ローラー間の位置関係−
図７の（ａ）は、軸方向から見たときの、定着ローラー３１、駆動ギア３１０、および欠歯ギア３２１、３２２の位置を示す側面図であり、（ｂ）は、（ａ）から駆動ギア３１０と第１欠歯ギア３２１とを除去したときの側面図であり、（ｃ）は、（ｂ）からローラー３１、３３以外の部材をすべて除去したときの側面図である。 -Positional relationship among cam, soaking roller and fixing roller-
7A is a side view showing the positions of the fixing roller 31, the driving gear 310, and the toothless gears 321 and 322 when viewed from the axial direction, and FIG. It is a side view when the gear 310 and the 1st partly tooth-missing gear 321 are removed, and (c) is a side view when all members except the rollers 31 and 33 are removed from (b).

支持部材３３Ａの下部は、図７の（ｂ）の示す切り込み３３Ｃを、図７の（ａ）の示すようにクリーニングローラー３４のシャフト３４Ｓに、定着ローラー３１の位置する側から引っ掛けている。支持部材３３Ａの上端はコイルバネ３３Ｂでフレーム３１Ｆの上面（図７は示していない。）に接続されている。このバネ３３Ｂの伸縮する範囲で支持部材３３Ａは、クリーニングローラー３４のシャフト３４Ｓのまわりを揺動可能である。 The lower portion of the support member 33A hooks the notch 33C shown in FIG. 7B on the shaft 34S of the cleaning roller 34 from the side where the fixing roller 31 is located, as shown in FIG. 7A. The upper end of the supporting member 33A is connected to the upper surface (not shown in FIG. 7) of the frame 31F by a coil spring 33B. The support member 33A can swing around the shaft 34S of the cleaning roller 34 within the range in which the spring 33B expands and contracts.

均熱ローラー３３のシャフト３３Ｓは支持部材３３Ａの中央部を貫通し、図４の（ｃ）の示すように軸受３３Ｌにより回転可能に支持されている。支持部材３３Ａは上記のような揺動が可能であるので、その揺動方向の力を均熱ローラー３３のシャフト３３Ｓがカム３６０から受けるとこのシャフト３３Ｓは、図７の（ｃ）の示すように、クリーニングローラー３４のシャフト３４Ｓのまわりを角度Δθの範囲で揺動する。これにより均熱ローラー３３は、定着ローラー３１に接触する位置と、それから距離ΔＧだけ離れた位置との間を移動する。 The shaft 33S of the soaking roller 33 penetrates through the central portion of the support member 33A and is rotatably supported by the bearing 33L as shown in FIG. Since the support member 33A is capable of swinging as described above, when the shaft 33S of the heat equalizing roller 33 receives the force in the swinging direction from the cam 360, the shaft 33S moves as shown in (c) of FIG. First, the cleaning roller 34 is swung around the shaft 34S within the range of the angle Δθ. As a result, the soaking roller 33 moves between a position in contact with the fixing roller 31 and a position separated from the fixing roller 31 by a distance ΔG.

カム３６０が均熱ローラー３３のシャフト３３Ｓに与える支持部材３３Ａの揺動方向の力は、駆動ギア３１０の回転力を利用して２枚の欠歯ギア３２１、３２２がカム３６０を回転させることにより生じる。まず、第１欠歯ギア３２１は、図７の（ａ）が示すような回転姿勢を取る間、駆動ギア３１０の回転力により回転する。この回転は、第１欠歯ギア３２１の裏面から突出した伝達部材３５０（たとえば図６の（ｂ）参照。）により第２欠歯ギア３２２を回転させる。したがって、第２欠歯ギア３２２と一体であるカム３６０も回転する。カム３６０は、図７の（ｂ）が示すように、板バネ３４１と爪３７０とにより両側（図では左右）から挟まれている。板バネ３４１は基端が支持部材３３Ａの上端に固定され、先端がカム３６０の外周のうち、カム３６０に対して定着ローラー３１が位置する側とは反対側（図７の（ａ）、（ｂ）では左側）の部分に接触している。この接触点が定着ローラー３１から実質的に遠のかないように、板バネ３４１は復元力をカム３６０の外周に対して加える。爪３７０は、軟質樹脂等の弾性体から成る棒状部材であり、フレーム３１Ｆのうち、その上面から下方へカム３６０と定着ローラー３１のシャフト３１Ｓとの間に伸びる部分（図７の（ａ）、（ｂ）は二点鎖線で示す。）に固定された基端から均熱ローラー３３のシャフト３３Ｓに向かって（図では左向きに）伸び、先端を第２欠歯ギア３２２の歯底面に接触させている。これにより爪３７０は、第２欠歯ギア３２２の逆回転（図７の（ａ）、（ｂ）では時計方向）を妨げると共に、第２欠歯ギア３２２との接触点が定着ローラー３１に実質的に近づかないように、弾性力を第２欠歯ギア３２２に対して加える。このように板バネ３４１と爪３７０とにより両側から挟まれているので、カム３６０はその外周全体を、図７の（ｃ）が二点鎖線で示すように、クリーニングローラー３４のシャフト３４Ｓに対して揺動させないまま回転する。一方、カム３６０の回転中心に対して均熱ローラー３３のシャフト３３Ｓは偏心しているので、カム３６０の回転に伴ってこのシャフト３３Ｓはカム３６０から支持部材３３Ａの揺動方向の力を受ける。 The force in the swinging direction of the support member 33A given to the shaft 33S of the heat equalizing roller 33 by the cam 360 is generated by the two toothless gears 321 and 322 rotating the cam 360 by utilizing the rotational force of the drive gear 310. Occurs. First, the first partly tooth-missing gear 321 is rotated by the rotational force of the drive gear 310 while taking the rotation posture as shown in FIG. This rotation causes the transmission member 350 (for example, see (b) of FIG. 6) protruding from the back surface of the first tooth-chipped gear 321 to rotate the second tooth-chipped gear 322. Therefore, the cam 360 that is integral with the second partly tooth-missing gear 322 also rotates. As shown in FIG. 7B, the cam 360 is sandwiched by the leaf spring 341 and the claw 370 from both sides (left and right in the figure). The leaf spring 341 has a base end fixed to the upper end of the support member 33A, and a tip end on the outer side of the cam 360 opposite to the side where the fixing roller 31 is located with respect to the cam 360 ((a) in FIG. In b), it is in contact with the part on the left side. The leaf spring 341 applies a restoring force to the outer circumference of the cam 360 so that this contact point is not substantially far from the fixing roller 31. The claw 370 is a rod-shaped member made of an elastic body such as soft resin, and extends from the upper surface of the frame 31F downward between the cam 360 and the shaft 31S of the fixing roller 31 ((a) in FIG. 7, (B) is indicated by a chain double-dashed line) from the base end fixed to the shaft 33S of the heat equalizing roller 33 (to the left in the figure), and the tip is brought into contact with the tooth bottom surface of the second toothless gear 322. ing. As a result, the pawl 370 prevents the reverse rotation of the second partly tooth-missing gear 322 (clockwise in FIGS. 7A and 7B), and the contact point with the second partly tooth-missing gear 322 is substantially fixed to the fixing roller 31. Elastic force is applied to the second partly tooth-missing gear 322 so as not to come close to each other. Since the cam 360 is thus sandwiched from both sides by the leaf spring 341 and the claw 370, the entire outer circumference of the cam 360 is relative to the shaft 34S of the cleaning roller 34, as shown by the chain double-dashed line in FIG. 7C. Rotate without rocking. On the other hand, since the shaft 33S of the heat equalizing roller 33 is eccentric with respect to the rotation center of the cam 360, the shaft 33S receives a force from the cam 360 in the swinging direction of the support member 33A as the cam 360 rotates.

図７の示す構造は、駆動ギア３１０と欠歯ギア３２１、３２２とを除き、均熱ローラー３３のシャフト３３Ｓの反対側の端部にも同様に設置されている。したがって、このシャフト３３Ｓは両端部で、カム３６０から支持部材３３Ａの揺動方向の力を受けてクリーニングローラー３４のシャフト３４Ｓのまわりを揺動する。これにより均熱ローラー３３は定着ローラー３１に接触し、それから離間する。 The structure shown in FIG. 7 is similarly installed at the end of the soaking roller 33 on the opposite side of the shaft 33S except for the drive gear 310 and the toothless gears 321 and 322. Therefore, the shaft 33S swings around the shaft 34S of the cleaning roller 34 by receiving a force in the swinging direction of the support member 33A from the cam 360 at both ends. As a result, the soaking roller 33 contacts the fixing roller 31 and separates from it.

−欠歯ギア間での回転力の伝達−
図８の（ａ）−（ｃ）は、カム３６０が１回転する期間の前半における第１欠歯ギア３２１の姿勢の変化を、回転角の順に示す模式的な平面図であり、（ｄ）−（ｆ）は、第１欠歯ギア３２１が（ａ）−（ｃ）の各姿勢を取るときにおける第２欠歯ギア３２２の姿勢を示す模式的な平面図である。 -Transmission of rotational force between toothless gears-
8A to 8C are schematic plan views showing changes in the posture of the first toothless gear 321 in the first half of the period in which the cam 360 makes one rotation, in the order of rotation angles, and FIG. -(F) is a schematic plan view showing the posture of the second tooth-chipped gear 322 when the first tooth-chipped gear 321 takes the postures of (a)-(c).

図８の（ａ）が示すように、有歯部４１Ｔが駆動ギア３１０を離脱した直後、保持部材３３２の先端は第１欠歯ギア３２１の表面の内溝４１Ｈの中に位置するので、第１欠歯ギア３２１の反時計方向ＣＣＷの回転に伴って内溝４１Ｈの先端の壁４１Ｘに衝突する。このとき、欠歯部４１Ｍが駆動ギア３１０に面しているので第１欠歯ギア３２１の回転が止まり、第１欠歯ギア３２１は停止姿勢に移行する。一方、第２欠歯ギア３２２は、図８の（ｄ）が示すように、有歯部４２Ｔが駆動ギア３１０と噛み合う回転姿勢を取っているので、駆動ギア３１０からの回転力でカム３６０と共に反時計方向ＣＣＷへ回転する。第１欠歯ギア３２１の停止により伝達部材３５０が停止しているので、第２欠歯ギア３２２の凹部４２Ｇの中ではコイルバネ３３５が凹部４２Ｇの後端の壁４２Ｘに押されて縮み始める。 As shown in (a) of FIG. 8, immediately after the toothed portion 41T leaves the drive gear 310, the tip of the holding member 332 is located in the inner groove 41H on the surface of the first toothless gear 321. As the one-toothed gear 321 rotates counterclockwise CCW, it collides with the wall 41X at the tip of the inner groove 41H. At this time, since the tooth-missing portion 41M faces the drive gear 310, the rotation of the first tooth-missing gear 321 stops, and the first tooth-missing gear 321 shifts to the stopped posture. On the other hand, the second partly tooth-missing gear 322 has a rotational posture in which the toothed portion 42T meshes with the drive gear 310 as shown in FIG. 8D, so that the rotational force from the drive gear 310 causes the cam 360 to move together. Rotate counterclockwise CCW. Since the transmission member 350 is stopped by stopping the first tooth-chipped gear 321, the coil spring 335 in the recess 42G of the second tooth-chipped gear 322 is pushed by the wall 42X at the rear end of the recess 42G and begins to contract.

図８の（ｂ）が示すように第１欠歯ギア３２１が停止姿勢を維持している間に、図８の（ｅ）が示すように有歯部４２Ｔが駆動ギア３１０から離脱するので第２欠歯ギア３２２の回転が止まり、第２欠歯ギア３２２は、欠歯部４２Ｍが駆動ギア３１０に面した停止姿勢を取る。このとき、第２欠歯ギア３２２の凹部４２Ｇの中ではコイルバネ３３５が、伝達部材３５０と凹部４２Ｇの後端の壁４２Ｘとの両方により押し縮められているので、その反作用として伝達部材３５０に対して周方向の力Ｆｐを加える。しかし、この時点ではまだ、第１欠歯ギア３２１の内溝４１Ｈの先端の壁４１Ｘに保持部材３３２の先端が接触しているので、第１欠歯ギア３２１は伝達部材３５０からの力Ｆｐに抗して停止姿勢を維持し続ける。 Since the toothed portion 42T is disengaged from the drive gear 310 as shown in (e) of FIG. 8 while the first toothless gear 321 maintains the stopped posture as shown in (b) of FIG. The rotation of the 2nd partly tooth-missing gear 322 is stopped, and the 2nd partly tooth-missing gear 322 assumes a stop posture in which the partly tooth-missing part 42M faces the drive gear 310. At this time, since the coil spring 335 is compressed by both the transmission member 350 and the rear end wall 42X of the recess 42G in the recess 42G of the second partly toothless gear 322, as a reaction to the transmission member 350. A circumferential force Fp is applied. However, at this point, the tip of the holding member 332 is still in contact with the wall 41X at the tip of the inner groove 41H of the first tooth-chipped gear 321, so that the first tooth-chipped gear 321 receives the force Fp from the transmission member 350. Continuing to maintain a stopped posture.

図８の（ｇ）は、欠歯ギア３２１、３２２が図８の（ｂ）、（ｅ）の示す停止姿勢を維持するときの定着ローラー３１と均熱ローラー３３とを模式的に示す側面図である。この図が二点鎖線で示すように、カム３６０はその外周のうち、第２欠歯ギア３２１の中心からの距離が最大の部分（図８の（ｂ）、（ｅ）、（ｇ）では切れ込み３６１の近傍）を定着ローラー３１の方へ向ける。これに伴い、均熱ローラー３３のシャフト３３Ｓはクリーニングローラー３４のシャフト３４Ｓのまわりを揺動し、定着ローラー３１から最も離れた位置へ移動する。これにより、均熱ローラー３３が定着ローラー３１から離間する。欠歯ギア３２１、３２２が停止姿勢を維持する間、両ローラー３１、３３は離間状態を維持する。 FIG. 8G is a side view schematically showing the fixing roller 31 and the heat equalizing roller 33 when the tooth-chipped gears 321 and 322 maintain the stopped postures shown in FIGS. 8B and 8E. Is. As shown by the chain double-dashed line in this figure, the cam 360 has a maximum distance from the center of the second partly tooth-chipped gear 321 in the outer periphery (in (b), (e), and (g) of FIG. 8). The vicinity of the notch 361) is directed toward the fixing roller 31. Along with this, the shaft 33S of the soaking roller 33 swings around the shaft 34S of the cleaning roller 34 and moves to a position farthest from the fixing roller 31. As a result, the soaking roller 33 separates from the fixing roller 31. While the toothless gears 321 and 322 maintain the stopped posture, the rollers 31 and 33 maintain the separated state.

図８の（ｂ）が示すように保持部材３３２の先端が第１欠歯ギア３２１の内溝４１Ｈの中に位置するので、初動部材のソレノイド３３３（図３参照。）はオン状態にある。したがって、離間している両ローラー３１、３３を接触させる場合、制御部はソレノイド３３３をオフさせる。これによりスライダー３３１が持ち上がるので保持部材３３２が上昇して第１欠歯ギア３２１の内溝４１Ｈから外溝４１Ｇへ移動し、壁４１Ｘから離れる。したがって、伝達部材３５０がコイルバネ３３５から受ける周方向の力Ｆｐにより第１欠歯ギア３２１は、図８の（ｃ）が示すように反時計方向ＣＣＷへ回転し、有歯部４１Ｔが駆動ギア３１０と噛み合う回転姿勢を再び取る。このようにコイルバネ３３５は、第１欠歯ギア３２１に対する初動部材の一部として機能する。 As shown in FIG. 8B, the tip of the holding member 332 is located in the inner groove 41H of the first toothless gear 321, so the solenoid 333 (see FIG. 3) of the initial moving member is in the ON state. Therefore, when the rollers 31 and 33 which are separated from each other are brought into contact with each other, the controller turns off the solenoid 333. As a result, the slider 331 is lifted, so that the holding member 332 moves up and moves from the inner groove 41H of the first toothless gear 321 to the outer groove 41G and away from the wall 41X. Therefore, the first tooth-missing gear 321 rotates counterclockwise CCW by the force Fp in the circumferential direction that the transmission member 350 receives from the coil spring 335, and the toothed portion 41T causes the driving gear 310 to rotate. Take the rotation posture that meshes with again. In this way, the coil spring 335 functions as a part of the initial moving member for the first toothless gear 321.

コイルバネ３３５が伸びきった後も第１欠歯ギア３２１はその回転姿勢により、駆動ギア３１０から回転力を受けて回転し続ける。これに伴い、伝達部材３５０は第２欠歯ギア３２２の凹部４２Ｇの中を再び前進し、程なく、図８の（ｆ）が示すように凹部４２Ｇの先端の壁４２Ｗに衝突してこの壁４２Ｗを反時計方向ＣＣＷへ押す。したがって、第２欠歯ギア３２２が反時計方向ＣＣＷへの回転を再開し、停止姿勢から回転姿勢へ移行する。 Even after the coil spring 335 is fully extended, the first partly tooth-missing gear 321 continues to rotate by receiving the rotational force from the drive gear 310 due to its rotational posture. Along with this, the transmission member 350 advances again in the recess 42G of the second tooth-chipped gear 322, and soon collides with the wall 42W at the tip of the recess 42G as shown in FIG. Push CCW counterclockwise. Therefore, the second partly tooth-missing gear 322 resumes rotation in the counterclockwise direction CCW, and shifts from the stopped posture to the rotated posture.

図９の（ａ）−（ｃ）は、カム３６０が１回転する期間の後半における第１欠歯ギア３２１の姿勢の変化を、回転角の順に示す模式的な平面図であり、（ｄ）−（ｆ）は、第１欠歯ギア３２１が（ａ）−（ｃ）の各姿勢を取るときにおける第２欠歯ギア３２２の姿勢を示す模式的な平面図である。
第１欠歯ギア３２１の回転に伴って保持部材３３２の先端は、図９の（ａ）が示すように第１欠歯ギア３２１の外溝４１Ｇの先端の壁４１Ｗに衝突する。このとき、欠歯部４１Ｍが駆動ギア３１０に面しているので第１欠歯ギア３２１の回転が止まり、第１欠歯ギア３２１は停止姿勢に移行する。一方、第２欠歯ギア３２２は、図９の（ｄ）が示すように回転姿勢を維持しているので、駆動ギア３１０からの回転力でカム３６０と共に反時計方向ＣＣＷへ回転し続ける。第１欠歯ギア３２１の停止により伝達部材３５０が停止しているので、第２欠歯ギア３２２の凹部４２Ｇの中ではコイルバネ３３５が凹部４２Ｇの後端の壁４２Ｘに押されて再び縮む。 9A to 9C are schematic plan views showing changes in the posture of the first toothless gear 321 in the latter half of the period in which the cam 360 makes one rotation, in the order of rotation angles, and FIG. -(F) is a schematic plan view showing the posture of the second tooth-chipped gear 322 when the first tooth-chipped gear 321 takes the postures of (a)-(c).
As the first tooth-chipped gear 321 rotates, the tip of the holding member 332 collides with the wall 41W of the tip of the outer groove 41G of the first tooth-chipped gear 321 as shown in FIG. 9A. At this time, since the tooth-missing portion 41M faces the drive gear 310, the rotation of the first tooth-missing gear 321 stops, and the first tooth-missing gear 321 shifts to the stopped posture. On the other hand, since the second partly tooth-missing gear 322 maintains the rotational posture as shown in FIG. 9D, the rotational force from the drive gear 310 continues to rotate in the counterclockwise CCW together with the cam 360. Since the transmission member 350 is stopped due to the stop of the first tooth-chipped gear 321, the coil spring 335 in the recess 42G of the second tooth-chipped gear 322 is pushed by the wall 42X at the rear end of the recess 42G and contracts again.

図９の（ｂ）が示すように第１欠歯ギア３２１が停止姿勢を維持している間に、図９の（ｅ）が示すように有歯部４２Ｔが駆動ギア３１０から離脱するので第２欠歯ギア３２２の回転が止まり、第２欠歯ギア３２２は停止姿勢を取る。このとき、第２欠歯ギア３２２の凹部４２Ｇの中ではコイルバネ３３５が伝達部材３５０に対して周方向の力Ｆｐを加える。しかし、この時点ではまだ、第１欠歯ギア３２１の外溝４１Ｇの先端の壁４１Ｗに保持部材３３２の先端が接触しているので、第１欠歯ギア３２１は伝達部材３５０からの力Ｆｐに抗して停止姿勢を維持し続ける。 As shown in (e) of FIG. 9, the toothed portion 42T is disengaged from the drive gear 310 while the first toothless gear 321 maintains the stopped posture as shown in (b) of FIG. 9. The rotation of the second partly tooth-missing gear 322 is stopped, and the second partly tooth-missing gear 322 is in a stopped posture. At this time, the coil spring 335 applies a circumferential force Fp to the transmission member 350 in the concave portion 42G of the second partly tooth-missing gear 322. However, at this point, the tip of the holding member 332 is still in contact with the wall 41W at the tip of the outer groove 41G of the first tooth-chipped gear 321, so that the first tooth-chipped gear 321 receives the force Fp from the transmission member 350. Continuing to maintain a stopped posture.

図９の（ｇ）は、欠歯ギア３２１、３２２が図９の（ｂ）、（ｅ）の示す停止姿勢を維持するときの定着ローラー３１と均熱ローラー３３とを模式的に示す側面図である。この図が二点鎖線で示すように、カム３６０はその外周のうち、第２欠歯ギア３２１の中心からの距離が最小の部分（図９の（ｂ）、（ｅ）、（ｇ）では切れ込み３６１とはカム３６０の中心に対して反対側の部分）を定着ローラー３１の方へ向ける。これに伴い、均熱ローラー３３のシャフト３３Ｓはクリーニングローラー３４のシャフト３４Ｓのまわりを揺動し、定着ローラー３１に最も近い位置へ移動する。これにより、均熱ローラー３３が定着ローラー３１に接触する。欠歯ギア３２１、３２２が停止姿勢を維持する間、両ローラー３１、３３は接触状態を維持する。 9G is a side view schematically showing the fixing roller 31 and the heat equalizing roller 33 when the tooth-chipped gears 321 and 322 maintain the stopped postures shown in FIGS. 9B and 9E. Is. As shown by the chain double-dashed line in this figure, the cam 360 has a minimum distance from the center of the second partly tooth-missing gear 321 in its outer periphery ((b), (e), (g) in FIG. 9). The portion opposite to the center of the cam 360 with respect to the notch 361 is directed toward the fixing roller 31. Along with this, the shaft 33S of the soaking roller 33 swings around the shaft 34S of the cleaning roller 34 and moves to a position closest to the fixing roller 31. As a result, the soaking roller 33 contacts the fixing roller 31. While the toothless gears 321 and 322 maintain the stopped posture, the rollers 31 and 33 maintain the contact state.

図９の（ｂ）が示すように保持部材３３２の先端は第１欠歯ギア３２１の外溝４１Ｇの中に位置するので、ソレノイド３３３はオフ状態にある。したがって、接触している両ローラー３１、３３を離間させる場合、制御部はソレノイド３３３をオンさせる。これによりスライダー３３１が落下するので保持部材３３２が下降して第１欠歯ギア３２１の外溝４１Ｇから内溝４１Ｈへ移動し、壁４１Ｗから離れる。したがって、伝達部材３５０がコイルバネ３３５から受ける周方向の力Ｆｐにより第１欠歯ギア３２１は、図９の（ｃ）が示すように反時計方向ＣＣＷへ回転して回転姿勢を再び取る。 As shown in FIG. 9B, the tip of the holding member 332 is located in the outer groove 41G of the first partly toothless gear 321, so the solenoid 333 is in the off state. Therefore, when separating the contacting rollers 31 and 33 from each other, the control unit turns on the solenoid 333. As a result, the slider 331 drops, so that the holding member 332 descends and moves from the outer groove 41G of the first toothless gear 321 to the inner groove 41H and away from the wall 41W. Therefore, due to the circumferential force Fp that the transmission member 350 receives from the coil spring 335, the first partly tooth-missing gear 321 rotates in the counterclockwise direction CCW as shown in FIG.

コイルバネ３３５が伸びきった後も第１欠歯ギア３２１はその回転姿勢により、駆動ギア３１０から回転力を受けて回転し続ける。これに伴い、伝達部材３５０は第２欠歯ギア３２２の凹部４２Ｇの中を再び前進し、程なく、図９の（ｆ）が示すように凹部４２Ｇの先端の壁４２Ｗに衝突してこの壁４２Ｗを反時計方向ＣＣＷへ押す。したがって、第２欠歯ギア３２２が反時計方向ＣＣＷへの回転を再開し、停止姿勢から回転姿勢へ移行する。 Even after the coil spring 335 is fully extended, the first partly tooth-missing gear 321 continues to rotate by receiving the rotational force from the drive gear 310 due to its rotational posture. Along with this, the transmission member 350 advances again in the recess 42G of the second tooth-missing gear 322, and soon collides with the wall 42W at the tip of the recess 42G as shown in FIG. Push CCW counterclockwise. Therefore, the second partly tooth-missing gear 322 resumes rotation in the counterclockwise direction CCW, and shifts from the stopped posture to the rotated posture.

以上のとおり、ソレノイド３３３のオンオフに応じて欠歯ギア３２１、３２２は停止姿勢から回転姿勢へ移行し、カム３６０を実質的に１８０°ずつ間欠的に回転させる。これにより均熱ローラー３３は定着ローラー３１に対する接触と離間とを間欠的に繰り返す。
［第１欠歯ギアの歯先の切り欠き］
図５の（ａ）、（ｂ）が示すように、第１欠歯ギア３２１の有歯部４１Ｔは、回転方向（図５の（ａ）では反時計方向ＣＣＷ、（ｂ）では時計方向ＣＷ）の先頭に位置する歯４１１の歯先が切り欠かれている。特にこの歯４１１は、歯先が切り欠かれていることにより、その歯先に傾斜面４１２を含む。この切り欠きにより、以下に述べるように、有歯部４１Ｔが駆動ギア３１０と噛み合い始める際、先頭の歯４１１の歯先が駆動ギア３１０の歯先と衝突すること、すなわち歯先当たりが回避される。 As described above, the tooth-chipped gears 321 and 322 shift from the stop posture to the rotation posture in response to the turning on/off of the solenoid 333, and intermittently rotate the cam 360 substantially by 180°. As a result, the soaking roller 33 intermittently repeats contact and separation with the fixing roller 31.
[Notch on the tip of the first toothless gear]
As shown in FIGS. 5A and 5B, the toothed portion 41T of the first partly tooth-missing gear 321 has a rotation direction (counterclockwise CCW in FIG. 5A, clockwise CW in FIG. 5B). ), the tooth tip of the tooth 411 located at the head is notched. In particular, the tooth 411 includes an inclined surface 412 at the tooth tip because the tooth tip is notched. Due to this notch, as described below, when the toothed portion 41T starts to mesh with the drive gear 310, the tip of the leading tooth 411 collides with the tip of the drive gear 310, that is, tooth tip contact is avoided. It

この歯先当たりの危険性は、第１欠歯ギア３２１と第２欠歯ギア３２２との隙間ＧＰ１のガタ（図４の（ｃ）参照。）が大きく設計されていることに起因する。実際、この設計では、各部材３３Ｓ、３２１の熱膨張が許容上限に達した最悪の場合が想定されているので、通常は隙間ＧＰ１が大きく確保される。しかし、これは、欠歯ギア３２１、３２２が停止姿勢を取る度に両ギア間の相対位置、特に位相差がばらつくことを意味する。その結果、第１欠歯ギア３２１がコイルバネ３３５の復元力を受けて回転し始めた際、有歯部４１Ｔの先頭の歯４１１が設計上の咬合位置に到達するタイミングが狂いやすい。 The risk of tooth tip contact is due to the large play (see (c) of FIG. 4) of the gap GP1 between the first tooth-chipped gear 321 and the second tooth-chipped gear 322. In fact, in this design, the worst case in which the thermal expansion of each member 33S, 321 has reached the allowable upper limit is assumed, so a large gap GP1 is usually secured. However, this means that the relative position between both gears, especially the phase difference, varies every time the tooth-chipped gears 321 and 322 take the stopped posture. As a result, when the first tooth-missing gear 321 starts to rotate due to the restoring force of the coil spring 335, the timing at which the leading tooth 411 of the toothed portion 41T reaches the designed occlusal position is likely to be incorrect.

図１０の（ａ）、（ｂ）は、第１欠歯ギア３２１がコイルバネ３３５の復元力を受けて回転し始めた際における第１欠歯ギア３２１と駆動ギア３１０との咬合部分を示す模式的な拡大図である。図の太い破線は先頭の歯４１１の設計上の咬合位置を示す。この位置に正しいタイミングで到達すれば、先頭の歯４１１はその直後、駆動ギア３１０の歯３１２と滑らかに接触する。先頭の歯４１１の歯先は第１欠歯ギア３２１のピッチ円ＰＴＣよりも外側に位置するので、駆動ギア３１０のその歯３１２から回転方向（図では反時計方向ＣＣＷ）に十分に大きな力を受ける。 FIGS. 10A and 10B are schematic diagrams showing the meshing portion between the first tooth-chipped gear 321 and the drive gear 310 when the first tooth-chipped gear 321 starts to rotate due to the restoring force of the coil spring 335. FIG. The thick broken line in the figure indicates the designed occlusal position of the leading tooth 411. When this position is reached at the correct timing, the leading tooth 411 immediately comes into contact with the tooth 312 of the drive gear 310 smoothly. Since the tip of the top tooth 411 is located outside the pitch circle PTC of the first toothless gear 321, a sufficiently large force is applied from the tooth 312 of the drive gear 310 in the rotation direction (counterclockwise CCW in the figure). receive.

図１０の（ａ）では、有歯部４１Ｔの先頭の歯４１１が設計上の咬合位置に到達するタイミングが遅い。図の太い実線は、この場合における先頭の歯４１１の実際の咬合位置を示す。図の細い実線は、仮に先頭の歯４１１が切り欠かれることなく、後続の歯と同じ形状であった場合を示す。この細い実線は、先頭の歯４１１の直後に位置する駆動ギア３１０の歯３１２と重なっている。これは、もし切り欠きがなければ有歯部４１Ｔの先頭の歯４１１の歯先が駆動ギア３１０のこの歯３１２と衝突し、すなわち歯先当たりが生じることを表す。実際には、図の太い実線が示すように先頭の歯４１１は歯先が切り欠かれている。特に傾斜面４１２は、回転方向ＣＣＷにおける端部が逆方向の端部よりも第１欠歯ギア３２１の中心に近いので、駆動ギア３１０の歯先の軌跡とは交差しない。すなわち、その歯先には先頭の歯４１１は衝突しない。 In FIG. 10A, the timing at which the leading tooth 411 of the toothed portion 41T reaches the designed occlusal position is late. The thick solid line in the figure shows the actual occlusion position of the leading tooth 411 in this case. The thin solid line in the figure shows the case where the leading tooth 411 is not cut out and has the same shape as the succeeding tooth. This thin solid line overlaps the tooth 312 of the drive gear 310 located immediately after the leading tooth 411. This means that, if there is no notch, the tooth tip of the leading tooth 411 of the toothed portion 41T collides with this tooth 312 of the drive gear 310, that is, tooth tip contact occurs. In fact, as shown by the thick solid line in the figure, the tip of the leading tooth 411 is notched. In particular, the inclined surface 412 does not intersect with the locus of the addendum of the drive gear 310 because the end in the rotation direction CCW is closer to the center of the first toothless gear 321 than the end in the opposite direction. That is, the top tooth 411 does not collide with the tooth tip.

図１０の（ｂ）では、有歯部４１Ｔの先頭の歯４１１が設計上の咬合位置に到達するタイミングが早い。図の太い実線は、この場合における先頭の歯４１１の実際の咬合位置を示す。図の細い実線は、仮に先頭の歯４１１が切り欠かれることなく、後続の歯と同じ形状であった場合を示す。この細い実線は、先頭の歯４１１の直前に位置する駆動ギア３１０の歯３１１の歯先と重なっている。これは、もし切り欠きがなければ有歯部４１Ｔの先頭の歯４１１が駆動ギア３１０のこの歯３１１の歯先と衝突し、すなわち歯先当たりが生じることを表す。実際には、図の太い実線が示すように先頭の歯４１１は歯先が切り欠かれているので、先頭の歯４１１は駆動ギア３１０の歯３１１の歯先とは衝突しない。または、衝突したとしてもその歯先に接触するのは傾斜面４１２である。回転方向ＣＣＷにおける傾斜面４１２の端部は逆方向の端部よりも第１欠歯ギア３２１の中心に近いので、駆動ギア３１０の歯３１１の歯先から傾斜面４１２が受ける衝撃力のうち、傾斜面４１２の法線方向の成分は傾斜面４１２の接線方向の成分よりも小さく抑えられる。したがって、第１欠歯ギア３２１は駆動ギア３１０から、回転方向ＣＣＷとは逆方向に弾く力を受けるものの、回転軸に向かう力を実質的には受けない。 In FIG. 10B, the timing at which the leading tooth 411 of the toothed portion 41T reaches the designed occlusal position is early. The thick solid line in the figure shows the actual occlusion position of the leading tooth 411 in this case. The thin solid line in the figure shows the case where the leading tooth 411 is not cut out and has the same shape as the succeeding tooth. The thin solid line overlaps the tip of the tooth 311 of the drive gear 310 located immediately before the leading tooth 411. This means that if there is no notch, the leading tooth 411 of the toothed portion 41T collides with the tooth tip of this tooth 311 of the drive gear 310, that is, tooth tip contact occurs. In fact, as shown by the thick solid line in the figure, the top tooth 411 is notched, so that the top tooth 411 does not collide with the tip of the tooth 311 of the drive gear 310. Alternatively, it is the inclined surface 412 that contacts the tip of the tooth even if the collision occurs. Since the end of the inclined surface 412 in the rotation direction CCW is closer to the center of the first toothless gear 321 than the end in the opposite direction, of the impact force that the inclined surface 412 receives from the tip of the tooth 311 of the drive gear 310, The component of the inclined surface 412 in the normal direction is suppressed to be smaller than the component of the inclined surface 412 in the tangential direction. Therefore, the first tooth-chipped gear 321 receives a force from the drive gear 310 in the direction opposite to the rotation direction CCW, but does not substantially receive the force toward the rotation axis.

［第２欠歯ギアの歯先の切り欠き］
図６の（ａ）が示すように、第２欠歯ギア３２２の有歯部４２Ｔは、回転方向（図では反時計方向ＣＣＷ）の先頭に位置する歯４２１の歯先が切り欠かれている。特にこの歯４２１は、歯先が切り欠かれていることにより、その歯先に傾斜面４２２を含む。この切り欠きにより、以下に述べるように、有歯部４２Ｔが駆動ギア３１０と噛み合い始める際、先頭の歯４２１の歯先が駆動ギア３１０の歯先と衝突すること、すなわち歯先当たりが回避される。 [Notch on the tip of the second missing tooth gear]
As shown in (a) of FIG. 6, the toothed portion 42T of the second partly tooth-missing gear 322 is notched at the tip of the tooth 421 located at the beginning in the rotation direction (counterclockwise CCW in the drawing). .. In particular, the tooth 421 includes an inclined surface 422 at the tooth tip because the tooth tip is notched. Due to this notch, as described below, when the toothed portion 42T starts to mesh with the drive gear 310, the tip of the leading tooth 421 collides with the tip of the drive gear 310, that is, tooth tip contact is avoided. It

この歯先当たりの危険性は主に、第２欠歯ギア３２２と均熱ローラー３３のシャフト３３Ｓとの隙間ＧＰ２のガタ（図４の（ｃ）参照。）が大きく設計されていることに起因する。実際、この設計では、各部材３３Ｓ、３２１の熱膨張が許容上限に達した最悪の場合が想定されているので、通常は隙間ＧＰ２が大きく確保される。しかし、これは、第１欠歯ギア３２１の伝達部材３５０が第２欠歯ギア３２２を押すことにより２枚の欠歯ギア３２１、３２２が一体的に回転する際、その回転軸が均熱ローラー３３のシャフト３３Ｓに対して傾斜しやすいことを意味する。この傾斜により、各欠歯ギア３２１、３２２の歯が駆動ギア３１０の同じ歯に接触するタイミングがずれるので、駆動ギア３１０に対する両欠歯ギア３２１、３２２間の実質的な位相差が過大になりやすい。この場合、第１欠歯ギア３２１が駆動ギア３１０にうまく噛み合った状態でも、第２欠歯ギア３２２が駆動ギア３１０に噛み合う際に歯先当たりが生じる危険性が生じる。 The risk of tooth tip contact is mainly due to the large play (see (c) of FIG. 4) of the gap GP2 between the second toothless gear 322 and the shaft 33S of the heat equalizing roller 33. To do. In fact, in this design, the worst case in which the thermal expansion of each of the members 33S and 321 has reached the allowable upper limit is assumed, so that a large gap GP2 is usually secured. However, this is because when the transmission member 350 of the first tooth-chipped gear 321 pushes the second tooth-chipped gear 322 to rotate the two tooth-chipped gears 321 and 322 integrally, the rotation axis of the two gears is equalized. This means that the shaft 33 of 33 is easily inclined with respect to the shaft 33S. Due to this inclination, the timing at which the teeth of the tooth-chipped gears 321 and 322 contact the same tooth of the drive gear 310 is deviated, so that the substantial phase difference between the tooth-chipped gears 321 and 322 with respect to the drive gear 310 becomes excessive. Cheap. In this case, even if the first partly tooth-missing gear 321 meshes well with the drive gear 310, there is a risk that tooth tip contact will occur when the second partly tooth-missing gear 322 meshes with the drive gear 310.

図１０の（ｃ）は、第１欠歯ギア３２１の伝達部材３５０が第２欠歯ギア３２２を押すことにより２枚の欠歯ギア３２１、３２２が一体的に回転する際の欠歯ギア３２１、３２２と駆動ギア３１０との咬合部分を示す模式的な拡大図である。図の細い破線は第１欠歯ギア３２１の有歯部４１Ｔの咬合位置を示す。伝達部材３５０が第２欠歯ギア３２２を押し始める時点ではすでに第１欠歯ギア３２１は回転姿勢にあるので、有歯部４１Ｔは正しい咬合位置にある。図の太い破線は第２欠歯ギア３２２の有歯部４２Ｔの設計上の咬合位置を示す。この位置に正しいタイミングで到達すれば、有歯部４２Ｔは第１欠歯ギア３２１の有歯部４１Ｔと位相が一致する。特に第２欠歯ギア３２２の有歯部４２Ｔの先頭の歯４２１は、直後に駆動ギア３１０の歯３１２と滑らかに接触する。先頭の歯４２１の歯先は第２欠歯ギア３２２のピッチ円ＰＴＣよりも外側に位置するので、駆動ギア３１０のその歯３１２から回転方向（図では反時計方向ＣＣＷ）に十分に大きな力を受ける。 FIG. 10C shows the tooth-chipped gear 321 when the two tooth-chipped gears 321 and 322 are integrally rotated by the transmission member 350 of the first tooth-chipped gear 321 pressing the second tooth-chipped gear 322. 3 is a schematic enlarged view showing an occlusal portion between 322 and a drive gear 310. FIG. The thin broken line in the figure indicates the occlusal position of the toothed portion 41T of the first toothless gear 321. At the time when the transmission member 350 starts to push the second tooth-missing gear 322, the first tooth-missing gear 321 is already in the rotation posture, so the toothed portion 41T is in the correct occlusal position. The thick broken line in the figure shows the designed occlusal position of the toothed portion 42T of the second toothless gear 322. If this position is reached at the correct timing, the toothed portion 42T will be in phase with the toothed portion 41T of the first toothless gear 321. In particular, the leading tooth 421 of the toothed portion 42T of the second partly toothless gear 322 makes smooth contact with the tooth 312 of the drive gear 310 immediately after. Since the tip of the top tooth 421 is located outside the pitch circle PTC of the second partly tooth-missing gear 322, a sufficiently large force is applied from the tooth 312 of the drive gear 310 in the rotation direction (counterclockwise CCW in the figure). receive.

図１０の（ｃ）の太い実線は、第２欠歯ギア３２２の有歯部４２Ｔの実際の咬合位置を示す。第２欠歯ギア３２２は第１欠歯ギア３２１の伝達部材３５０に押されることで回転し始めるので、第２欠歯ギア３２２の有歯部４２Ｔが第１欠歯ギア３２１の有歯部４１Ｔよりも位相が進むことはない。両有歯部４１Ｔ、４２Ｔ間に位相差が生じるのは、この太い実線が示すように、第２欠歯ギア３２２の有歯部４２Ｔが第１欠歯ギア３２１の有歯部４１Ｔよりも位相が遅れる場合である。図の細い実線は、仮に第２欠歯ギア３２２の有歯部４２Ｔの先頭の歯４２１が切り欠かれることなく、後続の歯と同じ形状であった場合を示す。この細い実線は、先頭の歯４２１の直後に位置する駆動ギア３１０の歯３１２と重なっている。これは、もし切り欠きがなければ有歯部４２Ｔの先頭の歯４２１の歯先が駆動ギア３１０のこの歯３１２と衝突し、すなわち歯先当たりが生じることを表す。実際には図の太い実線が示すように先頭の歯４２１は歯先が切り欠かれている。特に傾斜面４２２は、第１欠歯ギア３２１の傾斜面４１２とは逆に、回転方向ＣＣＷにおける端部よりも逆方向の端部が第２欠歯ギア３２２の中心に近いので、先頭の歯４２１は駆動ギア３１０の歯３１２とは衝突しない。または、衝突したとしても、その歯３１２に接触するのは傾斜面４２２である。回転方向ＣＣＷにおける傾斜面４２２の端部よりも逆方向の端部が第２欠歯ギア３２２の中心に近いので、駆動ギア３１０の歯３１２から傾斜面４２２が受ける衝撃力のうち、第２欠歯ギア３２２の中心方向の成分は回転方向ＣＣＷの成分よりも小さく抑えられる。したがって、第２欠歯ギア３２２は駆動ギア３１０から、回転方向ＣＣＷに加速する力を受けるものの、回転軸に向かう力を実質的には受けない。 The thick solid line in (c) of FIG. 10 indicates the actual occlusal position of the toothed portion 42T of the second partially toothed gear 322. The second tooth-chipped gear 322 starts to rotate by being pushed by the transmission member 350 of the first tooth-chipped gear 321, so that the toothed portion 42T of the second tooth-chipped gear 322 is the toothed portion 41T of the first tooth-chipped gear 321. The phase does not advance more than. A phase difference is generated between the toothed portions 41T and 42T because the toothed portion 42T of the second tooth-missing gear 322 is more in phase than the toothed portion 41T of the first tooth-missing gear 321 as indicated by the thick solid line. Is when there is a delay. The thin solid line in the figure shows a case where the leading tooth 421 of the toothed portion 42T of the second tooth-missing gear 322 is not cut out and has the same shape as the subsequent tooth. This thin solid line overlaps with the tooth 312 of the drive gear 310 located immediately after the leading tooth 421. This means that, if there is no notch, the tooth tip of the leading tooth 421 of the toothed portion 42T collides with this tooth 312 of the drive gear 310, that is, tooth tip contact occurs. In fact, as shown by the thick solid line in the figure, the tooth tip of the leading tooth 421 is notched. In particular, the inclined surface 422 is opposite to the inclined surface 412 of the first tooth-chipped gear 321, and the end portion in the opposite direction to the end portion in the rotation direction CCW is closer to the center of the second tooth-chipped gear 322, so that the first tooth 421 does not collide with the teeth 312 of the drive gear 310. Alternatively, even if a collision occurs, it is the inclined surface 422 that contacts the tooth 312. Since the end of the inclined surface 422 in the direction opposite to the end of the inclined surface 422 in the rotation direction CCW is closer to the center of the second partly tooth-missing gear 322, the second part of the impact force received from the teeth 312 of the drive gear 310 to the inclined surface 422 is the second part. The component in the center direction of the tooth gear 322 is suppressed smaller than the component in the rotation direction CCW. Therefore, the second partly tooth-missing gear 322 receives the force accelerating in the rotation direction CCW from the drive gear 310, but does not substantially receive the force toward the rotation axis.

［実施形態の利点］
本発明の上記の実施形態によるプリンター１００では、定着ローラー３１からの均熱ローラー３３の離間機構に、第１欠歯ギア３２１と第２欠歯ギア３２２との組み合わせを利用する。第１欠歯ギア３２１が初動部材３３１−３３５により停止姿勢から回転姿勢へ移行し、回転姿勢の第１欠歯ギア３２１が第２欠歯ギア３２２を停止姿勢から回転姿勢へ移行させる。この構成において、第２欠歯ギア３２２の有歯部４２Ｔは、回転方向ＣＣＷの先頭に位置する歯４２１の歯先が切り欠かれている。これにより、第１欠歯ギア３２１と第２欠歯ギア３２２との隙間ＧＰ１、および均熱ローラー３３のシャフト３３Ｓと第２欠歯ギア３２２との隙間ＧＰ２の両方においてガタが無視できない場合でも、少なくとも第２欠歯ギア３２２が駆動ギア３１０に噛み合う際に歯先当たりが生じる危険性を回避することができる。 [Advantages of Embodiment]
In the printer 100 according to the above-described embodiment of the present invention, a combination of the first tooth-chipped gear 321 and the second tooth-chipped gear 322 is used for the mechanism for separating the heat equalizing roller 33 from the fixing roller 31. The first tooth-chipped gear 321 shifts from the stopped posture to the rotation posture by the initial moving members 331-335, and the first tooth-chipped gear 321 in the rotation posture shifts the second tooth-chipped gear 322 from the stop posture to the rotation posture. In this configuration, the toothed portion 42T of the second partly tooth-missing gear 322 has a tooth tip of the tooth 421 located at the head in the rotation direction CCW cut out. As a result, even when the backlash cannot be ignored in both the gap GP1 between the first tooth-chipped gear 321 and the second tooth-chipped gear 322, and the gap GP2 between the shaft 33S of the heat equalizing roller 33 and the second tooth-chipped gear 322, It is possible to avoid the risk of tooth tip contact at least when the second toothless gear 322 meshes with the drive gear 310.

特に、第２欠歯ギア３２２の傾斜面４２２は、第１欠歯ギア３２１の傾斜面４１２とは逆に、回転方向ＣＣＷにおける端部よりも逆方向の端部が第２欠歯ギア３２２の中心に近い。この場合、第２欠歯ギア３２２の有歯部４２Ｔの先頭の歯４２１は駆動ギア３１０の歯３１２とは衝突しない。または、衝突したとしても傾斜面４２２がその歯３１２に接触するので、その歯３１２から傾斜面４２２が受ける衝撃力は実質上、第２欠歯ギア３２２を回転方向ＣＣＷに加速する成分しか含まない。したがって、第１欠歯ギア３２１が駆動ギア３１０にうまく噛み合えさえすれば、第２欠歯ギア３２２は自動的に駆動ギア３１０とうまく噛み合う。こうして、歯先当たりに起因する騒音が低減し、ギアのロック等の不具合と歯面損傷とが防止される。その結果、ギアの長寿命化が容易である。 In particular, the sloped surface 422 of the second partly tooth-missing gear 322 is opposite to the sloped surface 412 of the first partly tooth-missing gear 321 at the end opposite to the end in the rotational direction CCW of the second partly tooth-missing gear 322. Close to the center. In this case, the leading tooth 421 of the toothed portion 42T of the second partially toothed gear 322 does not collide with the tooth 312 of the drive gear 310. Alternatively, even if a collision occurs, the inclined surface 422 contacts the tooth 312, so that the impact force that the inclined surface 422 receives from the tooth 312 substantially includes only a component that accelerates the second toothless gear 322 in the rotation direction CCW. .. Therefore, as long as the first tooth-chipped gear 321 meshes well with the drive gear 310, the second tooth-chipped gear 322 automatically meshes well with the drive gear 310. In this way, noise resulting from tooth tip contact is reduced, and defects such as gear locking and tooth surface damage are prevented. As a result, it is easy to extend the life of the gear.

［変形例］
（A）本発明の実施形態による画像形成装置はレーザープリンター１００である。本発明の実施形態による画像形成装置はその他に、インクジェット等の他方式のプリンターであってもよく、ファクシミリ、コピー機等の単機能機であっても、または複合機であってもよい。 [Modification]
(A) The image forming apparatus according to the embodiment of the present invention is a laser printer 100. The image forming apparatus according to the embodiment of the present invention may be another type of printer such as an inkjet printer, a single function machine such as a facsimile machine or a copy machine, or a multifunction machine.

（B）欠歯ギア３２１、３２２の組み合わせを用いた回転力伝達機構は、定着ローラー３１からの均熱ローラー３３の離間機構に利用される。その他に、定着ローラー３１からの加圧ローラー３２の離間機構、給紙ローラー１２またはタイミングローラー１３のクラッチ等、定常的な回転から間欠的な運動を引き出す伝達機構には、欠歯ギア３２１、３２２の組み合わせが応用可能である。 (B) The rotational force transmission mechanism using the combination of the toothless gears 321 and 322 is used as a mechanism for separating the soaking roller 33 from the fixing roller 31. In addition, the transmission mechanism for extracting intermittent motion from the steady rotation, such as the mechanism for separating the pressure roller 32 from the fixing roller 31, the clutch of the sheet feeding roller 12 or the timing roller 13, has the toothless gears 321 and 322. The combination of is applicable.

本発明は画像形成装置における定着ローラーの駆動機構に関し、上記のとおり、定着ローラー３１から均熱ローラー３３を離間させる機構に２枚の欠歯ギア３２１、３２２の組み合わせを利用する際、第２欠歯ギア３２２の有歯部４２Ｔの先頭に位置する歯４２１の歯先を切り欠いておく。このように、本発明は明らかに産業上利用可能である。 The present invention relates to a fixing roller driving mechanism in an image forming apparatus. As described above, when a combination of two toothless gears 321 and 322 is used for the mechanism for separating the heat equalizing roller 33 from the fixing roller 31, the second missing gear is used. The tip of the tooth 421 located at the head of the toothed portion 42T of the tooth gear 322 is cut out. As described above, the present invention is obviously industrially applicable.

１００ レーザープリンター
３１ 定着ローラー
３１Ｓ 定着ローラーのシャフト
３１Ｆ フレーム
３１Ｃ フレームの側面上端の切り込み
３１Ｈ フレームの側面の貫通穴
３３ 均熱ローラー
３３Ｓ 均熱ローラーのシャフト
３３Ｌ 均熱ローラーのシャフトの軸受
３３Ａ 均熱ローラーの支持部材
３３Ｂ 支持部材上端のコイルバネ
３３Ｃ 支持部材下部の切り込み
３４ クリーニングローラー
３４Ｓ クリーニングローラーのシャフト
３４Ａ クリーニングローラーの支持部材
３４Ｂ 支持部材上端のコイルバネ
３００ 駆動機構
３１０ 駆動ギア
３１１、３１２ 駆動ギアの歯
３２１ 第１欠歯ギア
３２Ｏ 第１欠歯ギアの表面
３２Ｕ 第１欠歯ギアの裏面
３２２ 第２欠歯ギア
３２Ｖ 第２欠歯ギアのスリーブ
３３１ スライダー
３３２ 保持部材
３２Ｔ 保持部材の先端
３３３ ソレノイド
３３Ｐ ソレノイドのプランジャー
３３４ 緩衝部材
３３５ コイルバネ
３５０ 伝達部材
４１Ｍ 第１欠歯ギアの欠歯部
４１Ｔ 第１欠歯ギアの有歯部
４１１ 有歯部の先頭の歯
４１２ 歯先の傾斜部
４２Ｍ 第２欠歯ギアの欠歯部
４２Ｔ 第２欠歯ギアの有歯部
４２１ 有歯部の先頭の歯
４２２ 歯先の傾斜部
ＰＴＣ 欠歯ギアのピッチ円 100 Laser Printer 31 Fixing Roller 31S Fixing Roller Shaft 31F Frame 31C Notch at Upper Side of Frame 31H Through Hole on Side of Frame 33 Uniform Heat Roller 33S Uniform Heater Shaft 33L Uniform Heater Shaft Bearing 33A Uniform Heater Roller Support member 33B Coil spring at the upper end of the support member 33C Cuts at the lower part of the support member 34 Cleaning roller 34S Cleaning shaft 34A Cleaning roller support member 34B Coil spring at the upper end of the support member 300 Drive mechanism 310 Drive gear 311, 312 Drive gear teeth 321 First Partial tooth gear 32O First partly toothed gear front surface 32U First partly toothed gear back surface 322 Second partly toothed gear 32V Second partly toothed gear sleeve 331 Slider 332 Holding member 32T Holding member tip 333 Solenoid 33P Solenoid plunger 334 Cushioning member 335 Coil spring 350 Transmission member 41M Partial tooth part of the first partly toothless gear 41T Partial toothed part of the first partly toothed gear 411 Leading tooth of the partly toothed part 412 Tip sloped part 42M Partial part of the second partly toothless gear Tooth portion 42T Toothed portion of the second toothless gear 421 Tooth at the top of the toothed portion 422 Inclined portion of the tooth tip PTC Pitch circle of the toothless gear

Claims (14)

定常的に回転する１枚の駆動ギアの回転力を利用して可動部材を間欠的に変位させる回転力伝達機構であって、
それぞれの有歯部が前記駆動ギアに噛み合う回転姿勢を取ることのできるように同軸に配置された１対の欠歯ギアであり、回転姿勢を維持する間は同方向へ回転し、有歯部が前記駆動ギアから離脱すると、欠歯部が前記駆動ギアに面する停止姿勢を維持する第１欠歯ギアおよび第２欠歯ギアと、
前記第１欠歯ギアを停止姿勢から回転姿勢へ移行させる初動部材と、
前記第１欠歯ギアと一体に形成され、回転姿勢の前記第１欠歯ギアから回転力を前記第２欠歯ギアへ伝達することにより、前記第２欠歯ギアを停止姿勢から回転姿勢へ移行させる伝達部材と、
前記第２欠歯ギアの回転力で回転して外部の固定部材または前記可動部材との接触点を移動させることにより、前記固定部材に対して前記可動部材を変位させるカムと、
を備え、
前記初動部材は、
前記第１欠歯ギアと前記第２欠歯ギアとの間に周方向の力を加える付勢部材としてのバネと、
前記付勢部材の加える力に抗して前記第１欠歯ギアを停止姿勢に保持する保持部材と、
前記保持部材を変位させて前記第１欠歯ギアの保持を解除させる駆動部と、を含み、
前記第１欠歯ギアの有歯部において回転方向の先頭に位置する歯は、歯先が切り欠かれた傾斜面を含み、当該傾斜面は、回転方向の端部が逆方向の端部よりも前記第１欠歯ギアの中心に近く、
前記第２欠歯ギアの有歯部において回転方向の先頭に位置する歯は、歯先が切り欠かれた傾斜面を含み、当該傾斜面は、回転方向の端部よりも逆方向の端部が前記第２欠歯ギアの中心に近い
ことを特徴とする回転力伝達機構。 A rotational force transmission mechanism for intermittently displacing a movable member by utilizing the rotational force of one drive gear that constantly rotates,
The toothed portions are a pair of toothless gears that are coaxially arranged so as to be able to take a rotation posture that meshes with the drive gear, and rotate in the same direction while maintaining the rotation posture. When the gear is disengaged from the drive gear, a first partly tooth-missing gear and a second partly tooth-missing gear that maintain a stopped posture in which the partly toothless part faces the drive gear,
An initial moving member that shifts the first partly tooth-missing gear from a stopped posture to a rotating posture,
The second partly tooth-missing gear is formed integrally with the first partly toothless gear, and the rotational force is transmitted from the first partly toothless gear to the second partly toothless gear, whereby the second partly tooth-missing gear is moved from the stopped position to the rotating position. A transmission member to be transferred,
A cam for displacing the movable member with respect to the fixed member by rotating with a rotational force of the second toothless gear to move a contact point with an external fixed member or the movable member;
Equipped with
The initial member is
A spring as a biasing member that applies a force in the circumferential direction between the first toothless gear and the second toothless gear,
A holding member that holds the first toothless gear in a stopped posture against the force applied by the biasing member;
A drive unit that displaces the holding member to release the holding of the first tooth-missing gear,
The tooth located at the head in the rotation direction in the toothed portion of the first toothless gear includes an inclined surface with a tooth tip cut out, and the inclined surface has an end portion in the rotation direction more than an end portion in the opposite direction. Is also close to the center of the first toothless gear,
The tooth located at the head in the rotation direction in the toothed portion of the second toothless gear includes an inclined surface with a tooth tip cut out, and the inclined surface is an end portion in the direction opposite to the end portion in the rotation direction. Is close to the center of the second partly tooth-missing gear . 定常的に回転する１枚の駆動ギアの回転力を利用して可動部材を間欠的に変位させる回転力伝達機構であって、
それぞれの有歯部が前記駆動ギアに噛み合う回転姿勢を取ることのできるように同軸に配置された１対の欠歯ギアであり、回転姿勢を維持する間は同方向へ回転し、有歯部が前記駆動ギアから離脱すると、欠歯部が前記駆動ギアに面する停止姿勢を維持する第１欠歯ギアおよび第２欠歯ギアと、
前記第１欠歯ギアを停止姿勢から回転姿勢へ移行させる初動部材と、
回転姿勢の前記第１欠歯ギアから回転力を前記第２欠歯ギアへ伝達することにより、前記第２欠歯ギアを停止姿勢から回転姿勢へ移行させる伝達部材と、
前記第２欠歯ギアの回転力で回転して外部の固定部材または前記可動部材との接触点を移動させることにより、前記固定部材に対して前記可動部材を変位させるカムと、
を備え、
前記第２欠歯ギアの有歯部は、回転方向の先頭に位置する歯の歯先が切り欠かれており、
前記初動部材は、
前記第１欠歯ギアと前記第２欠歯ギアとの間に周方向の力を加える付勢部材と、
前記付勢部材の加える力に抗して前記第１欠歯ギアを停止姿勢に保持する保持部材と、
前記保持部材を変位させて前記第１欠歯ギアの保持を解除させる駆動部と、を含み、
前記第１欠歯ギアの表面には、前記第１欠歯ギアと同心で、半径が互いに異なる複数の弧状部分を含む溝が刻まれており、
前記保持部材は、先端が前記溝の中に位置し、かつ前記第１欠歯ギアの半径方向に変位可能に支持された突起部を含み、
前記突起部は先端を、前記溝のうち、いずれかの弧状部分の端に接触させることにより前記第１欠歯ギアを停止姿勢に保持し、
前記駆動部は、前記突起部を前記第１欠歯ギアの半径方向に変位させて前記突起部の先端を前記溝の別の弧状部分へ移動させることにより、前記保持部材に前記第１欠歯ギアの保持を解除させる
ことを特徴とする回転力伝達機構。 A rotational force transmission mechanism for intermittently displacing a movable member by utilizing the rotational force of one drive gear that constantly rotates,
The toothed portions are a pair of toothless gears that are coaxially arranged so as to be able to take a rotation posture that meshes with the drive gear, and rotate in the same direction while maintaining the rotation posture. When the gear is disengaged from the drive gear;
An initial moving member that shifts the first partly tooth-missing gear from a stopped posture to a rotating posture,
A transmission member for transferring the rotational force from the first partly tooth-missing gear in the rotating position to the second partly tooth-missing gear to shift the second partly tooth-missing gear from the stopped position to the rotating position;
A cam for displacing the movable member with respect to the fixed member by rotating with the rotational force of the second toothless gear to move a contact point with an external fixed member or the movable member;
Equipped with
In the toothed portion of the second toothless gear, the tip of the tooth located at the head in the rotation direction is cut out,
The initial member is
A biasing member that applies a circumferential force between the first toothless gear and the second toothless gear;
A holding member that holds the first toothless gear in a stopped posture against the force applied by the biasing member;
A drive unit that displaces the holding member to release the holding of the first tooth-missing gear,
A groove including a plurality of arc-shaped portions that are concentric with the first tooth-missing gear and that have different radii are engraved on the surface of the first tooth-missing gear.
The holding member includes a protrusion having a tip located in the groove and supported so as to be displaceable in a radial direction of the first toothless gear,
The protrusion holds the first tooth-chipped gear in a stopped posture by bringing the tip into contact with the end of one of the arc-shaped portions of the groove,
The drive unit displaces the protrusion in the radial direction of the first tooth-missing gear to move the tip of the protrusion to another arcuate portion of the groove, thereby causing the holding member to have the first tooth-missing tooth. A rotational force transmission mechanism that releases the holding of a gear. 前記第２欠歯ギアの有歯部において回転方向の先頭に位置する歯は、歯先が切り欠かれた傾斜面を含み、当該傾斜面は、回転方向の端部よりも逆方向の端部が前記第２欠歯ギアの中心に近いことを特徴とする請求項２に記載の回転力伝達機構。 The tooth located at the head in the rotation direction in the toothed portion of the second toothless gear includes an inclined surface with a tooth tip cut out , and the inclined surface is an end portion in the direction opposite to the end portion in the rotation direction. Is close to the center of the second partly tooth-missing gear, The torque transmission mechanism according to claim 2 . 前記第２欠歯ギアの有歯部において回転方向の先頭に位置する歯は、歯先の表面に、前記第２欠歯ギアの中心からの距離が前記第２欠歯ギアのピッチ円の半径よりも長い部分を含む請求項１から請求項３までのいずれかに記載の回転力伝達機構。 The tooth located at the head in the rotation direction in the toothed portion of the second toothless gear has a radius of a pitch circle of the second toothless gear on the surface of the tooth tip with a distance from the center of the second toothless gear. The rotational force transmission mechanism according to any one of claims 1 to 3, which includes a longer portion. 前記第１欠歯ギアの有歯部は、回転方向の先頭に位置する歯の歯先が切り欠かれていることを特徴とする請求項２または請求項３に記載の回転力伝達機構。 The rotating force transmitting mechanism according to claim 2 or 3 , wherein the toothed portion of the first toothless gear has a tooth tip of a tooth located at the head in the rotation direction cut out. 前記第１欠歯ギアの有歯部において回転方向の先頭に位置する歯は、歯先が切り欠かれた傾斜面を含み、当該傾斜面は、回転方向の端部が逆方向の端部よりも前記第１欠歯ギアの中心に近いことを特徴とする請求項５に記載の回転力伝達機構。 The tooth located at the head in the rotation direction in the toothed portion of the first toothless gear includes an inclined surface with a tooth tip cut out, and the inclined surface has an end portion in the rotation direction more than an end portion in the opposite direction. The rotating force transmission mechanism according to claim 5 , wherein is also close to the center of the first toothless gear. 前記第１欠歯ギアの有歯部において回転方向の先頭に位置する歯は、歯先の表面に、前記第１欠歯ギアの中心からの距離が前記第１欠歯ギアのピッチ円の半径よりも長い部分を含む請求項５または請求項６に記載の回転力伝達機構。 The tooth located at the head in the rotation direction in the toothed portion of the first toothless gear has a radius of a pitch circle of the first toothless gear on the surface of the tooth tip with a distance from the center of the first toothless gear. The torque transmission mechanism according to claim 5 or 6 , which includes a longer portion. 前記付勢部材は、
一端が前記第１欠歯ギアに固定され、他端が前記第２欠歯ギアに固定されたバネであって、前記保持部材が前記第１欠歯ギアを停止姿勢に保持する間、前記第２欠歯ギアの回転により復元力を高め、前記駆動部が前記保持部材に前記第１欠歯ギアの保持を解除させるのに伴い、当該復元力で前記第１欠歯ギアを前記第２欠歯ギアに対して回転させるバネを含む請求項１または請求項２に記載の回転力伝達機構。 The biasing member is
A spring, one end of which is fixed to the first toothless gear and the other end of which is fixed to the second toothless gear, while the holding member holds the first toothless gear in a stopped posture. The restoring force is increased by the rotation of the two-toothed gear, and as the driving unit causes the holding member to release the holding of the first toothless gear, the restoring force causes the first to-tooth gear to move to the second missing tooth gear. The torque transmission mechanism according to claim 1 or 2 , further comprising a spring that rotates with respect to the tooth gear. 前記第１欠歯ギアの表面には、前記第１欠歯ギアと同心で、半径が互いに異なる複数の弧状部分を含む溝が刻まれており、
前記保持部材は、先端が前記溝の中に位置し、かつ前記第１欠歯ギアの半径方向に変位可能に支持された突起部を含み、
前記突起部は先端を、前記溝のうち、いずれかの弧状部分の端に接触させることにより前記第１欠歯ギアを停止姿勢に保持し、
前記駆動部は、前記突起部を前記第１欠歯ギアの半径方向に変位させて前記突起部の先端を前記溝の別の弧状部分へ移動させることにより、前記保持部材に前記第１欠歯ギアの保持を解除させる
ことを特徴とする請求項１に記載の回転力伝達機構。 A groove including a plurality of arc-shaped portions that are concentric with the first tooth-missing gear and that have different radii are carved on the surface of the first tooth-missing gear,
The holding member includes a protrusion having a tip located in the groove and supported so as to be displaceable in the radial direction of the first toothless gear,
The protrusion holds the first toothless gear in a stopped posture by bringing the tip into contact with the end of one of the arc-shaped portions of the groove,
The drive unit displaces the protrusion in the radial direction of the first tooth-missing gear to move the tip of the protrusion to another arc-shaped portion of the groove, thereby causing the holding member to have the first tooth-missing tooth. The torque transmission mechanism according to claim 1 , wherein the holding of the gear is released. 前記第１欠歯ギアに面した前記第２欠歯ギアの表面は、前記第２欠歯ギアと同心弧状の凹部を含み、
前記伝達部材は、一端が前記凹部の中に位置し、他端が前記第１欠歯ギアに固定された柱状部を含み、
前記柱状部は、前記第１欠歯ギアの回転に伴い、前記一端で前記凹部の端を周方向に押すことにより、前記第２欠歯ギアを前記第１欠歯ギアの回転に連動して回転させる
ことを特徴とする請求項１から請求項９までのいずれかに記載の回転力伝達機構。 A surface of the second partially toothed gear facing the first partially toothed gear includes a concave portion that is concentric with the second partially toothed gear;
The transmission member includes a columnar portion having one end located in the recess and the other end fixed to the first toothless gear,
The columnar portion interlocks with the rotation of the first tooth-missing gear by pushing the end of the recess in the circumferential direction with the one end as the first tooth-missing gear rotates. The rotating force transmitting mechanism according to any one of claims 1 to 9, which is rotated. 前記第２欠歯ギアは、中心部から回転軸方向に突出するスリーブを同軸に含み、
前記第１欠歯ギアは、前記スリーブが挿入される穴を中心部に含む
請求項１から請求項１０までのいずれかに記載の回転力伝達機構。 The second partly tooth-missing gear coaxially includes a sleeve protruding from the center in the rotation axis direction,
The rotational force transmission mechanism according to any one of claims 1 to 10, wherein the first tooth-missing gear includes a hole into which the sleeve is inserted, in a central portion thereof. 前記第１欠歯ギアと前記第２欠歯ギアとの軸方向の間隔は、両欠歯ギアの温度が許容上限に達した場合でも実質的に詰まらない値に設計されていることを特徴とする請求項１から請求項１１までのいずれかに記載の回転力伝達機構。 The axial gap between the first tooth-chipped gear and the second tooth-chipped gear is designed to be a value that does not substantially clog even when the temperature of both tooth-chipped gears reaches an allowable upper limit. The torque transmission mechanism according to any one of claims 1 to 11. 画像形成装置に搭載され、シートに画像を熱定着させる定着装置であって、
シートに接触して加熱する定着ローラーと、
前記定着ローラーを定常的に回転させるモーターと、
前記定着ローラーに接触して従動回転する位置と、前記定着ローラーから離間する位置との間で変位可能に支持された別ローラーと、
前記モーターの回転力により定常的に回転する駆動ギアと、
前記駆動ギアの回転力を利用して前記別ローラーを前記定着ローラーから間欠的に離間させる請求項１から請求項１２までのいずれかに記載の回転力伝達機構と、
を備えた定着装置。 A fixing device that is mounted on an image forming apparatus and heat-fixes an image on a sheet,
A fixing roller that contacts the sheet and heats it,
A motor for constantly rotating the fixing roller,
A position that is driven to rotate in contact with the fixing roller and another roller that is displaceably supported between a position separated from the fixing roller,
A drive gear that constantly rotates due to the rotational force of the motor,
The rotational force transmission mechanism according to any one of claims 1 to 12, wherein the another roller is intermittently separated from the fixing roller by utilizing the rotational force of the drive gear.
Fixing device. シートを搬送する搬送装置と、
前記シートに画像を作成する作像装置と、
前記シートに前記画像を熱定着させる請求項１３に記載の定着装置と、
を備えた画像形成装置。 A transport device for transporting a sheet,
An image forming device for creating an image on the sheet,
The fixing device according to claim 13, wherein the image is thermally fixed on the sheet.
An image forming apparatus equipped with.
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