JP5783851B2

JP5783851B2 - Paper loading device

Info

Publication number: JP5783851B2
Application number: JP2011186881A
Authority: JP
Inventors: 直哉増田; 和之青木
Original assignee: Riso Kagaku Corp
Current assignee: Riso Kagaku Corp
Priority date: 2011-08-30
Filing date: 2011-08-30
Publication date: 2015-09-24
Anticipated expiration: 2031-08-30
Also published as: CN102963754B; JP2013049496A; CN102963754A

Description

本発明は、用紙を積載した用紙積載台が昇降機構部を介して昇降可能に画像形成装置に設置されている用紙積載装置に関する。 The present invention relates to a sheet stacking apparatus in which a sheet stacking table on which sheets are stacked is installed in an image forming apparatus so as to be movable up and down via a lifting mechanism.

一般的に、用紙に画像や文字を印刷する印刷装置や、用紙に画像や文字を複写する複写機などの画像形成装置には、用紙を積載する用紙積載台を備えた用紙積載装置が設置されている。 In general, in a printing apparatus that prints images and characters on paper and an image forming apparatus such as a copying machine that copies images and characters on paper, a paper stacking device having a paper stacking base for loading paper is installed. ing.

この種の用紙積載装置は各種の構造形態が適用されているが、一例として、孔版印刷機の一つの側面に、用紙を積載した給紙台が昇降機構部を介して上下方向に昇降可能に設置された画像形成装置用給紙装置がある（例えば、特許文献１参照）。 Various types of structures are applied to this type of paper stacking device. As an example, a paper feed table loaded with paper on one side of a stencil printing machine can be lifted up and down via a lifting mechanism. There is a paper feeding device for an image forming apparatus installed (see, for example, Patent Document 1).

特許文献１に開示された画像形成装置用給紙装置は、不図示の孔版印刷機の一つの側面に給紙ユニットが設置されており、且つ、この給紙ユニットの左右の側壁間に用紙を積載した給紙台が昇降機構部を介して用紙の積載量に応じて上下方向に昇降可能（上下動可能）に設けられている。 The paper feeding device for an image forming apparatus disclosed in Patent Document 1 is provided with a paper feeding unit on one side surface of a stencil printing machine (not shown), and paper is placed between the left and right side walls of the paper feeding unit. The loaded paper feed table is provided so as to be movable up and down (movable up and down) in the vertical direction according to the amount of paper loaded via the lifting mechanism.

具体的に説明すると、図６に示す如く、従来の画像形成装置用給紙装置１００において、用紙Ｐを積載した給紙台１０１を昇降（上下動）させるための昇降機構部１１０では、給紙ユニット（図示せず）の左右の側壁１１１に略垂直方向に延びるガイド孔１１２が形成されていると共に、このガイド孔１１２の端縁に沿ってガイドレール１１３が形成されている。 More specifically, as shown in FIG. 6, in the conventional sheet feeding device 100 for the image forming apparatus, the lifting mechanism unit 110 for moving up and down (moves up and down) the sheet feeding table 101 on which the sheets P are loaded is used for sheet feeding. Guide holes 112 extending in a substantially vertical direction are formed in the left and right side walls 111 of the unit (not shown), and guide rails 113 are formed along the edges of the guide holes 112.

一方、複数枚の用紙Ｐを積載した給紙台１０１は、左右両側端にそれぞれブラケット１０２を介してローラ軸１０３が固定されており、このローラ軸１０３はガイドローラ１０４を回転可能に支持すると共に、外部の昇降部材１１４に連結している。そして、ガイドローラ１０４はガイド孔１１２内に上下方向移動可能に配置されると共にガイドレール１１３に当接している。 On the other hand, the paper feed table 101 on which a plurality of sheets P are stacked has a roller shaft 103 fixed to both left and right ends via brackets 102. The roller shaft 103 rotatably supports the guide roller 104. , Connected to an external lifting member 114. The guide roller 104 is disposed in the guide hole 112 so as to be movable in the vertical direction and is in contact with the guide rail 113.

また、昇降部材１１４には駆動チェーン１１５の一端部が連結されており、この駆動チェーン１１５は上方に延びて回転自在なターンスプロケット１１６に係合すると共に下方に折り返し、駆動モータ１１７のモータ軸１１７ａに固着したピニオンギア１１８及びこのピニオンギア１１８に噛合したギア１１９により同軸上で一体的に回転駆動される下方の駆動スプロケット１２０に係合し、さらに上方に折り返して、駆動チェーン１１５の他端部が引張バネ１２１の一端部に連結している。更に、引張バネ１２１は上方に延びて、引張バネ１２１の他端部が側壁１１１に設けられたブラケット１２２に掛止されている。 Further, one end of a drive chain 115 is connected to the elevating member 114, and this drive chain 115 extends upward and engages with a rotatable turn sprocket 116 and folds downward, so that the motor shaft 117a of the drive motor 117 is engaged. The other end of the drive chain 115 is engaged with a lower drive sprocket 120 that is coaxially and rotationally driven by a pinion gear 118 fixed to the pinion gear 118 and a gear 119 meshed with the pinion gear 118, and further folded upward. Is connected to one end of the tension spring 121. Further, the tension spring 121 extends upward, and the other end of the tension spring 121 is hooked on a bracket 122 provided on the side wall 111.

そして、上記の構成により、昇降機構部１１０の駆動モータ１１７を駆動してピニオンギア機構１１８，１１９を介して駆動スプロケット１２０を矢印Ｂ１方向に回転させることにより駆動チェーン１１５が矢印Ｂ２方向に移動し、駆動チェーン１１５に連結した昇降部材１１４を介して給紙台１０１が引張バネ１２１に補助されながら上昇するようになっている。一方、駆動スプロケット１２０を上記とは逆方向に回転させれば、昇降部材１１４を介して給紙台１０１が下降するようになっている。 With the above configuration, the drive chain 117 is moved in the direction of arrow B2 by driving the drive motor 117 of the lifting mechanism 110 and rotating the drive sprocket 120 in the direction of arrow B1 via the pinion gear mechanisms 118 and 119. The paper feed table 101 is lifted up with the aid of the tension spring 121 via the elevating member 114 connected to the drive chain 115. On the other hand, when the drive sprocket 120 is rotated in the direction opposite to the above, the sheet feed table 101 is lowered via the elevating member 114.

特開２０１０−８９８９０号公報JP 2010-89890 A

ところで、一般的に、用紙Ｐを積載した用紙積載台を昇降機構部を介して昇降可能に画像形成装置に設置した場合に、用紙Ｐを満載したときの荷重を基準にして昇降機構部内に設けた駆動モータを選定すると、強力なトルクを発生できる駆動モータを必要とするが、特許文献１に開示された画像形成装置用給紙装置１００内に設けた昇降機構部１１０では、重力方向と、給紙台重量及び用紙積載重量とを考慮して、給紙台１０１が上昇するときに駆動チェーン１１５を介して引張バネ１２１で補助し、この引張バネ１２１の付勢力により給紙台１０１が上昇するときの荷重と、給紙台１０１が下降するときの荷重とを平均化することにより、駆動モータ１１７の必要トルクを低減することが可能である。 By the way, in general, when a sheet stacking table on which sheets P are stacked is installed in the image forming apparatus so as to be movable up and down via the lifting mechanism, the lifting mechanism is provided in the lifting mechanism based on the load when the sheets P are fully loaded. If the drive motor is selected, a drive motor capable of generating a strong torque is required. However, in the lifting mechanism 110 provided in the image forming apparatus paper feeder 100 disclosed in Patent Document 1, In consideration of the weight of the paper feed table and the paper stacking weight, when the paper feed table 101 is raised, it is assisted by the tension spring 121 via the drive chain 115, and the paper feed table 101 is raised by the urging force of the tension spring 121. The required torque of the drive motor 117 can be reduced by averaging the load when the sheet feeding table 101 is lowered and the load when the sheet feeding table 101 is lowered.

しかしながら、特許文献１に開示された技術的思想では、駆動チェーン１１５の一端部を昇降部材１１４を介して給紙台１０１に連結し、且つ、駆動チェーン１１５の他端部を引張バネ１２１の一端部に連結しているので、給紙台１０１が昇降するときの移動量は駆動チェーン１１５に直接伝達されるために、引張バネ１２１の変位量（撓み量）は給紙台１０１の昇降時の移動量と同程度必要となり、自然長を含めた引張バネ１２１のバネ長さは給紙台１０１の昇降時の移動量よりも当然長くなっている。 However, in the technical idea disclosed in Patent Document 1, one end portion of the drive chain 115 is connected to the paper feed table 101 via the elevating member 114, and the other end portion of the drive chain 115 is connected to one end of the tension spring 121. Since the movement amount when the paper feed table 101 moves up and down is directly transmitted to the drive chain 115, the displacement amount (deflection amount) of the tension spring 121 is determined when the paper feed table 101 is raised and lowered. The amount of movement is required to be approximately the same as the amount of movement, and the spring length of the tension spring 121 including the natural length is naturally longer than the amount of movement when the paper feed table 101 is raised and lowered.

従って、多数枚の用紙を積載できる給紙台１０１の昇降時の移動量が大きい場合には、引張バネ１２１のバネ長さが給紙台１０１の昇降時の移動量よりも当然長くなり、引張バネ１２１の設置位置を設定することが困難になると共に、引張バネ１２１の設置位置によっては画像形成装置用給紙装置１００又は不図示の孔版印刷機が大型化してしまうという問題が発生する。 Therefore, when the amount of movement of the paper feed table 101 on which a large number of sheets can be loaded is large, the spring length of the tension spring 121 is naturally longer than the amount of movement of the paper feed table 101 when it is lifted. It becomes difficult to set the installation position of the spring 121, and depending on the installation position of the tension spring 121, there arises a problem that the paper feeding device 100 for an image forming apparatus or a stencil printing machine (not shown) becomes large.

そこで、用紙を積載した用紙積載台が昇降機構部を介して昇降可能に画像形成装置に設置された用紙積載装置において、用紙を満載した用紙積載台を昇降機構部を介して上昇させる際の駆動モータへの負荷を軽減させるように補助する引張バネのバネ長さを短く設定でき、且つ、引張バネを用紙積載装置又は画像形成装置内の空きスペースに効率良く設置できる用紙積載装置を提供することを目的とする。 Therefore, in the paper stacking apparatus installed in the image forming apparatus so that the paper stacking base on which the paper is loaded can be moved up and down via the lifting mechanism, the drive when the paper stacking base full of paper is lifted through the lifting mechanism the tension spring length of the spring that assists in reducing the load on the motor can be set short, and, providing a paper for Ru can be efficiently installed stacking apparatus in an empty space of the sheet stacking apparatus or the image forming in the device a tensile spring The purpose is to do.

本発明は上記課題に鑑みてなされたものであり、請求項１に記載の発明は、用紙を積載した用紙積載台が昇降機構部を介して昇降可能に画像形成装置に設置された用紙積載装置において、
前記昇降機構部は、
前記画像形成装置に上下方向に沿って取り付けられたラックと、
前記ラックに噛合し、且つ、前記用紙積載台に取り付けられた回転駆動源により回転駆動されて前記用紙積載台と一体にこの用紙積載台を前記ラックに沿って昇降させるギアと、
前記ギアの直径よりもプーリ外周部が大径に形成されて該ギアと一体に同軸上で回転駆動され、且つ、前記プーリ外周部又は該プーリ外周部の近傍に一端部を固着させたワイヤを前記ギアの回転方向に巻回させたプーリと、
前記ワイヤの他端部が一端部に連結されて他端部が固定部に掛止された引張バネと、
を備え、
前記ギアの回転に伴って前記プーリ外周部から引き出される前記ワイヤの引き出し量又は前記プーリ外周部に巻き取られる前記ワイヤの巻き取り量を、前記用紙積載台の昇降時の移動量よりも大きく設定して前記ワイヤに連結した前記引張バネを変位させ、前記用紙積載台の昇降時の移動量をＸ、前記引張バネの変位量をＹとしたときに、Ｘ／Ｙ＞１の関係が成立するように前記ギアの直径と前記プーリ外周部の直径とを設定することを特徴とする用紙積載装置である。 SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and the invention according to claim 1 is a paper stacking apparatus in which a paper stacking table on which sheets are stacked is installed in an image forming apparatus so as to be lifted and lowered via a lifting mechanism. In
The lifting mechanism is
A rack attached to the image forming apparatus along a vertical direction;
A gear that meshes with the rack and is rotationally driven by a rotational drive source attached to the paper stacking base to raise and lower the paper stacking base along the rack together with the paper stacking base;
A wire having a pulley outer peripheral portion formed larger in diameter than the diameter of the gear and being rotationally driven coaxially with the gear and having one end fixed to the pulley outer peripheral portion or the vicinity of the pulley outer peripheral portion. A pulley wound in the rotational direction of the gear;
A tension spring in which the other end of the wire is connected to one end and the other end is hooked to the fixed portion;
With
The amount of the wire drawn out from the outer peripheral portion of the pulley with the rotation of the gear or the amount of winding of the wire wound around the outer peripheral portion of the pulley is set larger than the moving amount when the paper stacking table is moved up and down. Then, when the tension spring connected to the wire is displaced , the amount of movement of the paper stacking table when moving up and down is X, and the amount of displacement of the tension spring is Y, the relationship X / Y> 1 is established. a sheet stacking apparatus characterized that you set the diameter of the gear and the diameter of the pulley outer periphery such that.

また、請求項２に記載の発明は、前記プーリ外周部に巻回された前記ワイヤの他端部側をワイヤ方向転換用プーリを介して前記用紙の搬送方向と直交する用紙幅方向に方向転換させて、前記ワイヤの他端部側を前記用紙幅方向に沿って設置した前記引張バネの一端部に連結させることを特徴とする請求項１に記載の用紙積載装置である。 According to a second aspect of the present invention, the other end portion of the wire wound around the pulley outer peripheral portion is turned in the paper width direction orthogonal to the paper transport direction via a wire direction changing pulley. by a sheet stacking apparatus according to the other end of the wire to claim 1, characterized in that connected to one end of the tension spring which is placed along the sheet width direction.

請求項１記載の用紙積載装置によると、用紙を積載した用紙積載台を昇降機構部を介して昇降させる際に、昇降機構部は、画像形成装置に上下方向に沿って取り付けられたラックと、用紙積載台に取り付けられ回転駆動源によりラックと噛合しながら回転駆動されるギアと、ギアと一体に同軸上で回転駆動され且つプーリ外周部又はプーリ外周部の近傍に一端部を固着させたワイヤをギアの回転方向に巻回させたプーリと、ワイヤの他端部が一端部に連結されて他端部が固定部に掛止された引張バネと、を備え、ギアの回転に伴ってプーリのプーリ外周部から引き出されるワイヤの引き出し量又はプーリ外周部に巻き取られるワイヤの巻き取り量を、用紙積載台の昇降時の移動量よりも大きく設定してワイヤに連結した引張バネを変位させ、用紙積載台の昇降時の移動量をＸ、引張バネの変位量をＹとしたときに、Ｘ／Ｙ＞１の関係が成立するようにギアの直径とプーリ外周部の直径とを設定しているので、用紙積載台の昇降時に回転駆動源の回転負荷を引張バネで補助できると共に、引張バネのバネ長さを短く設定できるためにこの引張バネを用紙積載装置又は画像形成装置内の空きスペースに効率良く設置できるので、用紙積載装置又は画像形成装置の小型化に寄与できる。 According to the paper stacking apparatus of claim 1, when the paper stacking table on which the paper is stacked is lifted and lowered via the lifting mechanism, the lifting mechanism is mounted on the image forming apparatus along the vertical direction. A gear mounted on the paper stacking table and rotated while being engaged with the rack by a rotation driving source, and a wire that is rotationally driven coaxially with the gear and has one end fixed to the pulley outer periphery or the vicinity of the pulley outer periphery. And a tension spring in which the other end portion of the wire is connected to one end portion and the other end portion is hooked to the fixed portion, and the pulley rotates with the rotation of the gear. The pull-out amount of the wire drawn from the outer periphery of the pulley or the winding amount of the wire wound around the outer periphery of the pulley is set to be larger than the amount of movement when the paper stacking table is raised and lowered to displace the tension spring connected to the wire. , The movement amount at the time of paper stacking plate of the lifting X, the displacement of the tension spring when the Y, by setting the diameters of the pulley outer periphery of the gear so that the relation of X / Y> 1 is satisfied Therefore, when the paper stacking table is moved up and down, the rotational load of the rotation drive source can be assisted by the tension spring, and the spring length of the tension spring can be set short. Therefore, it is possible to contribute to downsizing of the paper stacking apparatus or the image forming apparatus.

また、請求項２記載の用紙積載装置によると、プーリ外周部に巻回されたワイヤの他端部側をワイヤ方向転換用プーリを介して用紙の搬送方向と直交する用紙幅方向に方向転換させて、ワイヤの他端部側を用紙幅方向に沿って設置した引張バネの一端部に連結させることで、用紙積載台上に積載される用紙の積載量が多量で用紙積載台の昇降時の移動量が大きい場合に、用紙積載台の移動を補助する引張バネのバネ長さが長くなっても、引張バネを画像形成装置内の空きスペースに用紙幅方向に沿って効率よく配置できるので、画像形成装置を小型化することが可能となる。 According to the paper stacking apparatus of claim 2, the other end portion of the wire wound around the outer peripheral portion of the pulley is changed in the paper width direction perpendicular to the paper transport direction via the wire direction changing pulley. By connecting the other end of the wire to one end of a tension spring installed along the paper width direction, the amount of paper loaded on the paper loading table is large and When the amount of movement is large, even if the spring length of the tension spring that assists the movement of the paper loading table is increased, the tension spring can be efficiently arranged in the empty space in the image forming apparatus along the paper width direction. It is possible to reduce the size of the image forming apparatus.

本発明に係る用紙積載装置の全体構成を説明するために一部破断して示した上面図である。1 is a top view partially broken away for explaining the overall configuration of a paper stacking apparatus according to the present invention. 本発明に係る用紙積載装置において、用紙積載台が下降位置に至っている状態を一部破断して示した側面図である。In the paper stacking apparatus according to the present invention, the paper stacking table is partially cut away and shown in a side view. 本発明に係る用紙積載装置において、用紙積載台が上昇位置に至っている状態を一部破断して示した側面図である。In the paper stacking device according to the present invention, FIG. 本発明に係る用紙積載装置において、左右一対のプーリ付きギアを拡大して示した斜視図である。FIG. 4 is an enlarged perspective view of a pair of left and right gears with pulleys in the paper stacking apparatus according to the present invention. 本発明に係る用紙積載装置において、用紙積載台の移動量と引張バネの変位量との関係を説明するために模式的に示した図である。In the paper stacking apparatus according to the present invention, it is a diagram schematically showing the relationship between the amount of movement of the paper stacking base and the amount of displacement of the tension spring. 従来の画像形成装置用給紙装置を説明するための側面図である。It is a side view for demonstrating the conventional paper feeder for image forming apparatuses.

以下に本発明に係る用紙積載装置の一実施例について、図１〜図５を参照して詳細に説明する。 Hereinafter, an embodiment of a paper stacking apparatus according to the present invention will be described in detail with reference to FIGS.

本発明に係る用紙積載装置は、印刷装置や複写機などの画像形成装置に適用されており、用紙を積載した用紙積載台が昇降機構部を介して上下方向に昇降可能に画像形成装置に設置されている。 The paper stacking apparatus according to the present invention is applied to an image forming apparatus such as a printing apparatus or a copying machine, and the paper stacking base on which the paper is stacked is installed in the image forming apparatus so that it can be lifted up and down via a lifting mechanism. Has been.

この際、本発明に係る用紙積載装置は、未印刷又は未複写の用紙を積載してこの用紙を画像形成装置内に給紙する用紙給紙台を備えた用紙給紙装置や、画像形成装置内で処理された印刷済み又は複写済みの用紙を排紙しながら積載する用紙排紙台を備えた用紙排紙装置のいずれにも適用可能であるが、以下の実施例では用紙積載装置を用紙給紙装置に適用した場合について説明し、略同じ構成による用紙排紙装置についての説明を省略する。 In this case, the sheet stacking apparatus according to the present invention includes a sheet feeding apparatus provided with a sheet feeding stand for stacking unprinted or non-copied sheets and feeding the sheets into the image forming apparatus, and an image forming apparatus. In the following embodiments, the paper stacking device is used as a paper stacking device. However, in the following embodiments, the paper stacking device is used as a paper stacking device. A description will be given of a case where the present invention is applied to a paper feeding device, and a description of a paper discharge device having substantially the same configuration will be omitted.

図１〜図３に示す如く、本発明に係る用紙積載装置（用紙給紙装置）１０では、用紙Ｐを積載した用紙積載台（用紙給紙台）１１が印刷装置や複写機などの画像形成装置１の一つの側面１ａに昇降機構部２０を介して用紙Ｐの積載量に応じて上下方向に昇降可能に設置されている。 As shown in FIGS. 1 to 3, in a paper stacking apparatus (paper feeding apparatus) 10 according to the present invention, a paper stacking base (paper feeding base) 11 on which sheets P are stacked is used to form an image such as a printing apparatus or a copying machine. It is installed on one side surface 1a of the apparatus 1 so that it can be moved up and down in accordance with the loading amount of the paper P via the lifting mechanism 20.

上記した用紙積載台１１は、外形サイズの異なる１種類の用紙Ｐを例えば４０００枚程度積載可能となるように剛性のある金属材又は樹脂材を用いて直方形状に形成されており、且つ、用紙積載台１１の先端部１１ｂ側が画像形成装置１の一つの側面１ａに形成した開口部１ｂ内に進入した状態で設置されている。 The above-described paper stacking table 11 is formed in a rectangular shape using a rigid metal material or resin material so that, for example, about 4000 sheets of one type of paper P having different external sizes can be stacked, The front end 11 b side of the loading platform 11 is installed in a state of entering into an opening 1 b formed on one side surface 1 a of the image forming apparatus 1.

また、用紙積載台１１の上面１１ａには、用紙Ｐの搬送方向と直交する用紙Ｐの幅方向をガイドする左右一対のガイドフェンス１２Ｌ，１２Ｒ（図１のみ図示）が不図示のガイドフェンス移動手段を介して左右に移動自在に間隔を離して設けられており、これによりＡ３サイズ，Ａ４サイズ，封筒サイズなどの１種類の用紙Ｐが多数枚積載可能になっている。 A pair of left and right guide fences 12L and 12R (only shown in FIG. 1) for guiding the width direction of the paper P perpendicular to the transport direction of the paper P are provided on the upper surface 11a of the paper stacking base 11 as guide fence moving means (not shown). In this way, a large number of sheets of one type P such as A3 size, A4 size, and envelope size can be stacked.

更に、用紙積載台１１の上方部位には、給紙ローラ１３と捌きローラ１４とが左右一対のアーム１５，１５に軸支されており、両ローラ１３，１４は不図示のローラ回転駆動源によりそれぞれ反時計方向に回転可能になっている。 Further, a paper feed roller 13 and a separating roller 14 are pivotally supported by a pair of left and right arms 15, 15 above the paper stacking table 11, and both rollers 13, 14 are driven by a roller rotation drive source (not shown). Each can rotate counterclockwise.

そして、用紙Ｐの搬送方向の上流側に配置された給紙ローラ１３は、用紙積載台１１上に積層された最上層の用紙Ｐに回転しながら当接して、最上層の用紙Ｐを搬送方向下流側に向かって給紙している。 The paper feed roller 13 disposed on the upstream side in the transport direction of the paper P is in contact with the uppermost paper P stacked on the paper stacking table 11 while rotating, thereby feeding the uppermost paper P in the transport direction. Paper is fed toward the downstream side.

一方、給紙ローラ１３よりも下流側に配置された捌きローラ１４には摩擦板１６（図２，図３）が添接しており、給紙ローラ１３より給紙された用紙Ｐは捌きローラ１４と摩擦板１６との間で挟持搬送されながら一枚ずつ分離されて重送が防止され、この後、画像形成装置１内に搬送されるようになっている。 On the other hand, a friction plate 16 (FIGS. 2 and 3) is attached to the separating roller 14 disposed on the downstream side of the sheet feeding roller 13, and the sheet P fed from the sheet feeding roller 13 is disposed on the separating roller 14. Are separated one by one while being nipped and conveyed between the friction plate 16 and the friction plate 16 to prevent double feeding, and thereafter conveyed into the image forming apparatus 1.

ここで、実施例の要部を構成し、且つ、用紙積載台１１を昇降させるための昇降機構部２０について説明する。 Here, an elevating mechanism unit 20 that constitutes a main part of the embodiment and that elevates and lowers the paper stacking base 11 will be described.

上記した昇降機構部２０では、用紙積載台１１を上下方向に昇降させるために左右一対のラック部材２１Ｌ，２１Ｒが画像形成装置１の一つの側面１ａに間隔を離して上下方向に向って左右平行に垂直に取り付けられており、且つ、左右一対のラック部材２１Ｌ，２１Ｒは長尺なラック歯２１ａが両者２１Ｌ，２１Ｒ間に設置した用紙積載台１１の後方側に向かって左右対称に形成されている。 In the elevating mechanism 20 described above, a pair of left and right rack members 21L and 21R are spaced parallel to one side surface 1a of the image forming apparatus 1 in order to elevate the sheet stacking table 11 in the vertical direction. The pair of left and right rack members 21L and 21R are formed symmetrically with respect to the rear side of the sheet stacking table 11 in which long rack teeth 21a are installed between the two rack members 21L and 21R. Yes.

一方、用紙積載台１１の先端部１１ｂ側の左側面部１１ｃに平板状のブラケット２２が取り付けられ、且つ、用紙積載台１１の先端部１１ｂ側の右側面部１１ｄにＬ字状のモータブラケット２３が取り付けられている。この際、Ｌ字状のモータブラケット２３は、水平な上面２３ａが平坦面に形成され、垂直な側面２３ｂが用紙積載台１１の右側面部１１ｄに固着されている。 On the other hand, a flat bracket 22 is attached to the left side surface portion 11c on the front end portion 11b side of the paper stacking base 11, and an L-shaped motor bracket 23 is attached to the right side surface portion 11d on the front end portion 11b side of the paper stacking base 11. It has been. At this time, the L-shaped motor bracket 23 has a horizontal upper surface 23 a formed as a flat surface, and a vertical side surface 23 b fixed to the right side surface portion 11 d of the paper stacking table 11.

そして、右側のモータブラケット２３に形成した上面２３ａには、回転駆動源となる駆動モータ２４がモータ軸２４ａを下方に向けて垂直に取り付けられており、且つ、モータ軸２４ａにウォームギア２５が固着されている。 On the upper surface 23a formed on the right motor bracket 23, a drive motor 24 as a rotational drive source is vertically attached with the motor shaft 24a facing downward, and the worm gear 25 is fixed to the motor shaft 24a. ing.

また、Ｌ字状のモータブラケット２３の上面２３ａと直交する側面２３ｂには、段付きシャフト２６が用紙積載台１１の右側面部１１ｄの外側に向って横設されており、この段付きシャフト２６に軸着させたアイドラーギア２７がモータ軸２４ａに固着させたウォームギア２５に噛合している。 Further, a stepped shaft 26 is provided on the side surface 23 b orthogonal to the upper surface 23 a of the L-shaped motor bracket 23 so as to extend outward from the right side surface portion 11 d of the paper stacking table 11. The idler gear 27 attached to the shaft meshes with the worm gear 25 fixed to the motor shaft 24a.

また、左側のブラケット２２及び右側のモータブラケット２３の側面２３ｂ上で左右一対のラック部材２１Ｌ，２１Ｒ側に向かう左右対称位置には、左右一対の段付きシャフト２８Ｌ，２８Ｒが用紙積載台１１の左側面部１１ｃ及び右側面部１１ｄの各外側に向って横設されており、これら左右一対の段付きシャフト２８Ｌ，２８Ｒに左右一対のプーリ付きギア２９Ｌ，２９Ｒが軸着されている。 In addition, a pair of left and right stepped shafts 28L and 28R are located on the left side of the sheet stacking base 11 at symmetrical positions on the left side bracket 22 and the side surface 23b of the right motor bracket 23 toward the pair of left and right rack members 21L and 21R. A pair of left and right pulley-equipped gears 29L and 29R are pivotally attached to the pair of left and right stepped shafts 28L and 28R.

上記した左右一対のプーリ付きギア２９Ｌ，２９Ｒは、図４に拡大して示す如く、左右一対のラック部材２１Ｌ，２１Ｒの各ラック歯２１ａに噛合するギア部２９ａと、このギア部２９ａに同軸的に連接されて後述する左右一対のワイヤ３０Ｌ，３０Ｒをギア部２９ａの回転方向に巻回させるプーリ部２９ｂと、左右一対の段付きシャフト２８Ｌ，２８Ｒに軸着される中心孔２９ｃとが樹脂材などを用いて一体形成されている。 The pair of left and right pulley-equipped gears 29L and 29R are, as shown in an enlarged view in FIG. 4, a gear portion 29a that meshes with each rack tooth 21a of the pair of left and right rack members 21L and 21R, and coaxial with the gear portion 29a. A pulley portion 29b that is connected to the left and right wires 30L and 30R, which will be described later, in the rotational direction of the gear portion 29a, and a center hole 29c that is pivotally attached to the pair of left and right stepped shafts 28L and 28R. Etc. are formed integrally.

尚、実施例では、左右一対のプーリ付きギア２９Ｌ，２９Ｒを一体形成しているが、これに限定されるものではなく、ギア（２９ａ相当）とプーリ（２９ｂ相当）とを別体に形成して両者が同軸上で一体的に回転できる構造であれば良いものである。 In the embodiment, the pair of left and right pulley-equipped gears 29L and 29R are integrally formed. However, the present invention is not limited to this, and the gear (equivalent to 29a) and the pulley (equivalent to 29b) are formed separately. Any structure can be used as long as both of them can rotate integrally on the same axis.

この際、右側のプーリ付きギア２９Ｒのギア部２９ａは、右側のラック部材２１Ｒのラック歯２１ａに噛合していると共に、アイドラーギア２７（図１〜図３）にも噛合してモータ軸２４ａに固着させたウォームギア２５を介して駆動モータ２４によって回転駆動されるようになっているが、左側のプーリ付きギア２９Ｌのギア部２９ａは、左側のラック部材２１Ｌのラック歯２１ａのみに噛合している。 At this time, the gear portion 29a of the right pulley gear 29R meshes with the rack teeth 21a of the right rack member 21R and also meshes with the idler gear 27 (FIGS. 1 to 3) to the motor shaft 24a. The gear 29a of the left pulley-equipped gear 29L meshes only with the rack teeth 21a of the left rack member 21L, though the drive motor 24 is rotationally driven through the fixed worm gear 25. .

上記から、左右一対のラック部材２１Ｌ，２１Ｒを画像形成装置１の一つの側面１ａの左右に取り付け、且つ、用紙積載台１１の左右に取り付けた左右一対のプーリ付きギア２９Ｌ，２９Ｒの各ギア部２９ａを左右一対のラック部材２１Ｌ，２１Ｒの各ラック歯２１ａに噛合させることで、用紙積載台１１を左右に傾くことなく略水平に昇降させることが可能になっていると共に、駆動モータ２４を搭載した用紙積載台１１の昇降動作は左右一対のラック部材２１Ｌ，２１Ｒに対して左右一対のプーリ付きギア２９Ｌ，２９Ｒを介して自走式となっている。 From the above, the left and right pair of rack members 21L and 21R are attached to the left and right of one side surface 1a of the image forming apparatus 1 and the gear portions of the pair of left and right pulley-equipped gears 29L and 29R attached to the left and right of the sheet stacking base 11, respectively. By engaging 29a with the rack teeth 21a of the pair of left and right rack members 21L and 21R, the sheet stacking base 11 can be raised and lowered substantially horizontally without tilting left and right, and the drive motor 24 is mounted. The lifting and lowering operation of the sheet stacking table 11 is self-propelled via a pair of left and right gears 29L and 29R with respect to the pair of left and right rack members 21L and 21R.

また、左右一対のプーリ付きギア２９Ｌ，２９Ｒの各プーリ部２９ｂは、ギア部２９ａより小径に形成されてこのギア部２９ａに連接する連接用ボス部２９ｂ１と、下フランジ部２９ｂ２と、ギア部２９ａより大径に形成されて左側のワイヤ３０Ｌ又は右側のワイヤ３０Ｒをギア部２９ａの回転方向に巻回させるプーリ外周部２９ｂ３と、上フランジ部２９ｂ４とからなり、左側のワイヤ３０Ｌ又は右側のワイヤ３０Ｒは各一端部をプーリ外周部２９ｂ３又はこのプーリ外周部２９ｂ３の近傍の下フランジ部２９ｂ２もしくは上フランジ部２９ｂ４に固着させて、左側のワイヤ３０Ｌ又は右側のワイヤ３０Ｒをプーリ外周部２９ｂ３よりも大径に形成された上下のフランジ部２９ｂ２，２９ｂ４により脱線しないようにガイドしながらプーリ外周部２９ｂ３に沿って巻回させている。 The pulley portions 29b of the pair of left and right gears 29L and 29R have a connecting boss portion 29b1, a lower flange portion 29b2, and a gear portion 29a that are formed to have a smaller diameter than the gear portion 29a and are connected to the gear portion 29a. A left outer wire 30L or a right wire 30R is formed of a pulley outer peripheral portion 29b3 that is formed to have a larger diameter and winds the left wire 30L or the right wire 30R in the rotation direction of the gear portion 29a, and an upper flange portion 29b4. Each end is fixed to the pulley outer peripheral portion 29b3 or the lower flange portion 29b2 or the upper flange portion 29b4 in the vicinity of the pulley outer peripheral portion 29b3, and the left wire 30L or the right wire 30R has a larger diameter than the pulley outer peripheral portion 29b3. Pulley while guiding so as not to derail by the upper and lower flange portions 29b2, 29b4 formed in And then wound along the peripheral portion 29b3.

再び図１〜図３に戻り、左右一対のラック部材２１Ｌ，２１Ｒの各外側面２１ｂには、左右一対の段付きシャフト３１Ｌ，３１Ｒが外側に向って横設されており、これら左右一対の段付きシャフト３１Ｌ，３１Ｒに左右一対のワイヤ通過用プーリ３２Ｌ，３２Ｒが軸着されている。 1 to 3 again, a pair of left and right stepped shafts 31L and 31R are provided laterally outwardly on each outer surface 21b of the pair of left and right rack members 21L and 21R. A pair of left and right wire passing pulleys 32L and 32R are attached to the attached shafts 31L and 31R.

更に、画像形成装置１内の左右の側壁１ｃ，１ｄの近傍に左右一対の段付きシャフト３３Ｌ，３３Ｒが設置されており、これら左右一対の段付きシャフト３３Ｌ，３３Ｒにワイヤ方向転換用プーリ３４Ｌ，３４Ｒが軸着されている。 Further, a pair of left and right stepped shafts 33L and 33R are installed in the vicinity of the left and right side walls 1c and 1d in the image forming apparatus 1. The pair of left and right stepped shafts 33L and 33R is connected to a wire direction changing pulley 34L, 34R is axially attached.

そして、左右一対のプーリ付きギア２９Ｌ，２９Ｒの各プーリ部２９ｂのプーリ外周部２９ｂ３に巻回させた左右一対のワイヤ３０Ｌ，３０Ｒの各他端部側を左右一対のワイヤ通過用プーリ３２Ｌ，３２Ｒに沿って通過させた後に、画像形成装置１内に設置した左右一対のワイヤ方向転換用プーリ３４Ｌ，３４Ｒでワイヤ方向を用紙Ｐの搬送方向と直交する用紙幅方向に方向転換させて、画像形成装置１内で用紙幅方向に沿って設けた左右一対の引張バネ３５Ｌ，３５Ｒの各一端部に連結させると共に、左右一対の引張バネ３５Ｌ，３５Ｒの各他端部を画像形成装置１内に設置した左右一対の固定部３６Ｌ，３６Ｒに掛止させている。 And the other end side of the pair of left and right wires 30L and 30R wound around the pulley outer peripheral portion 29b3 of the pulley portion 29b of the pair of left and right gears 29L and 29R is connected to the pair of left and right wire passing pulleys 32L and 32R. , The wire direction is changed in the sheet width direction perpendicular to the conveyance direction of the sheet P by the pair of left and right wire direction changing pulleys 34L and 34R installed in the image forming apparatus 1 to form an image. The pair of left and right tension springs 35L and 35R provided along the paper width direction in the apparatus 1 is connected to one end of the pair, and the other end of the pair of left and right tension springs 35L and 35R is installed in the image forming apparatus 1. The left and right fixed portions 36L and 36R are hooked.

この際、用紙積載台１１上に積載される用紙Ｐの最大積載枚数は前述したように４０００枚程度と多量であるので、用紙積載台１１が昇降するときの移動量が４４０ｍｍ程度と大きくなり、これに伴って、用紙積載台１１の昇降を補助する左右一対の引張バネ３５Ｌ，３５Ｒのバネ長さも長くなるので、左右一対の引張バネ３５Ｌ，３５Ｒを画像形成装置１内で用紙幅方向に沿って設ける場合に、図２，図３に示したように左右一対の引張バネ３５Ｌ，３５Ｒが互い干渉しないように両者３５Ｌ，３５Ｒの設置高さを変えている。従って、左右一対の引張バネ３５Ｌ，３５Ｒを画像形成装置１内の空きスペースに効率良く配置できる。 At this time, since the maximum number of sheets P stacked on the sheet stacking table 11 is as large as about 4000 as described above, the moving amount when the sheet stacking table 11 is raised and lowered is as large as about 440 mm. Along with this, the spring length of the pair of left and right tension springs 35L and 35R that assist in raising and lowering the sheet stacking table 11 also increases, so that the pair of left and right tension springs 35L and 35R are aligned in the sheet width direction in the image forming apparatus 1. 2 and 3, the installation height of both the pair of left and right tension springs 35L and 35R is changed so that they do not interfere with each other. Therefore, the pair of left and right tension springs 35L and 35R can be efficiently arranged in the empty space in the image forming apparatus 1.

尚、用紙積載台１１上に積載される用紙Ｐの積載量が少ない用紙積載装置１０では、用紙積載台１１の昇降時の移動量が小さくなり、これに伴って、用紙積載台１１の昇降を補助する左右一対の引張バネ３５Ｌ，３５Ｒのバネ長さも短くなるので、左右一対のワイヤ方向転換用プーリを設ける必要はなく、左右一対のワイヤ３０Ｌ，３０Ｒの各他端部側を左右一対のワイヤ通過用プーリ３２Ｌ，３２Ｒに沿って通過させた後に左右一対の引張バネ３５Ｌ，３５Ｒの各一端部に直接連結させても良く、この場合には左右一対の引張バネ３５Ｌ，３５Ｒを用紙積載装置１０又は画像形成装置１内の空きスペースに設置すれば良いものであるので、用紙積載装置１０又は画像形成装置１の小型化に寄与できる。 It should be noted that in the paper stacking apparatus 10 having a small amount of paper P loaded on the paper stacking base 11, the amount of movement when the paper stacking base 11 is moved up and down becomes small, and accordingly, the paper stacking base 11 is moved up and down. Since the spring lengths of the pair of left and right tension springs 35L and 35R to assist are shortened, it is not necessary to provide a pair of left and right wire direction changing pulleys, and the other end of each of the pair of left and right wires 30L and 30R is connected to the pair of left and right wires. After passing along the passing pulleys 32L and 32R, the pair of left and right tension springs 35L and 35R may be directly coupled to one end of the pair of left and right tension springs 35L and 35R. Alternatively, it can be installed in an empty space in the image forming apparatus 1, which can contribute to the downsizing of the paper stacking apparatus 10 or the image forming apparatus 1.

次に、上記のように構成した用紙積載装置１０の動作について、図２，図３，図５を用いて用紙積載台１１の右側について説明し、駆動モータが取り付けられていない用紙積載台１１の左側も右側と同期して同様に動作するので、左右の動作については必要に応じて述べる。 Next, the operation of the sheet stacking apparatus 10 configured as described above will be described on the right side of the sheet stacking table 11 with reference to FIGS. 2, 3, and 5. Since the left side also operates in synchronism with the right side, the left and right operations will be described as necessary.

まず、図２に示す如く、用紙積載装置１０が初期状態であるとき、又は、用紙積載台１１上に用紙Ｐが最大量積載されているときには、用紙積載台１１が最も下方位置に下降している。 First, as shown in FIG. 2, when the paper stacking apparatus 10 is in the initial state or when the maximum amount of paper P is stacked on the paper stacking base 11, the paper stacking base 11 is lowered to the lowest position. Yes.

そして、用紙Ｐを給紙する場合には、駆動モータ２４を駆動して右側のラック部材２１Ｒのラック歯２１ａに噛合している右側のプーリ付きギア２９Ｒのギア部２９ａを時計方向に回転させると、右側のプーリ付きギア２９Ｒと一体に用紙積載台１１が右側のラック部材２１Ｒに沿って上昇するので、用紙積載台１１上に積層した最上層の用紙Ｐが給紙ローラ１３に当接する給紙位置まで用紙積載台１１を上昇させている。 When the paper P is fed, when the drive motor 24 is driven and the gear portion 29a of the right pulley-equipped gear 29R meshed with the rack teeth 21a of the right rack member 21R is rotated clockwise. The sheet stacking table 11 rises along the right rack member 21R integrally with the right pulley gear 29R, so that the uppermost sheet P stacked on the sheet stacking table 11 is in contact with the sheet feeding roller 13. The paper stacking base 11 is raised to the position.

一方、用紙Ｐの給紙が終了して用紙積載台１１を初期位置まで下降させる場合には、上昇時とは逆に駆動モータ２４を介して右側のプーリ付きギア２９Ｒのギア部２９ａを反時計方向に回転させれば良い。 On the other hand, when the feeding of the paper P is completed and the paper stacking base 11 is lowered to the initial position, the gear portion 29a of the right pulley-equipped gear 29R is counterclockwise via the drive motor 24, as opposed to when it is raised. Rotate in the direction.

次に、図３に示す如く、用紙積載台１１上に積層した用紙Ｐの積載量が少ない場合には、用紙Ｐの積載量に応じて用紙積載台１１を上昇させれば良い。 Next, as shown in FIG. 3, when the loading amount of the sheets P stacked on the sheet loading table 11 is small, the sheet loading table 11 may be raised according to the loading amount of the sheets P.

そして、図５に示す如く、用紙積載台１１を上昇させるときに左側の説明を省略して右側についてのみ述べると、右側のラック部材２１Ｒのラック歯２１ａに噛合している右側のプーリ付きギア２９Ｒのギア部２９ａを時計方向に回転させると、右側のプーリ付きギア２９Ｒのプーリ部２９ｂのプーリ外周部２９ｂ３に巻回している右側のワイヤ３０Ｒの他端部側は引き出されるので、ワイヤ引き出し量に応じて右側の引張バネ３５Ｒは縮む方向に変位する。 As shown in FIG. 5, when the left side description is omitted and the right side is described only when the paper stacking base 11 is lifted, the right pulley-equipped gear 29R engaged with the rack teeth 21a of the right rack member 21R. When the gear portion 29a is rotated clockwise, the other end portion of the right wire 30R wound around the pulley outer peripheral portion 29b3 of the pulley portion 29b of the right pulley gear 29R is pulled out. Accordingly, the right tension spring 35R is displaced in the contracting direction.

一方、用紙積載台１１を下降させるときに右側のラック部材２１Ｒのラック歯２１ａに噛合している右側のプーリ付きギア２９Ｒのギア部２９ａを反時計方向に回転させると、右側のプーリ付きギア２９Ｒのプーリ部２９ｂのプーリ外周部２９ｂ３に巻回している右側のワイヤ３０Ｒの他端部側は巻き取られるので、ワイヤ巻き取り量に応じて右側の引張バネ３５Ｒは伸びる方向に変位する。 On the other hand, when the gear 29a of the right pulley gear 29R meshing with the rack teeth 21a of the right rack member 21R is rotated counterclockwise when the paper stacking base 11 is lowered, the right pulley gear 29R is rotated. Since the other end portion of the right wire 30R wound around the pulley outer peripheral portion 29b3 of the pulley portion 29b is wound, the right tension spring 35R is displaced in the extending direction in accordance with the amount of wire winding.

ここで、右側のプーリ付きギア２９Ｒのギア部２９ａの直径をＤ１（ｍｍ）、右側のプーリ付きギア２９Ｒのプーリ部２９ｂのプーリ外周部２９ｂ３の直径をＤ２（ｍｍ）、用紙積載台１１の昇降時の移動量をＸ（ｍｍ）、移動量Ｘに応じて回転する右側のプーリ付きギア２９Ｒの回転数をＮ（ｒｐｍ）、用紙積載台１１が上昇する時の右側のワイヤ３０Ｒの引き出し量又は用紙積載台１１が下降する時の右側のワイヤ３０Ｒの巻き取り量をＬ（ｍｍ）、右側の引張バネ３５Ｒの変位量（撓み量）をＹ（ｍｍ）とすると、右側の引張バネ３５Ｒの変位量（撓み量）Ｙはワイヤ３０Ｒの引き出し量又は巻き取り量Ｌから用紙積載台１１の昇降時の移動量Ｘを引いた差分となるために、用紙積載台１１の昇降時の移動量Ｘと右側の引張バネ３５Ｒの変位量（撓み量）Ｙは上記したＤ１，Ｄ２に起因する。 Here, the diameter of the gear portion 29a of the right pulley-equipped gear 29R is D1 (mm), the diameter of the pulley outer peripheral portion 29b3 of the pulley portion 29b of the right pulley-equipped gear 29R is D2 (mm), The movement amount at the time is X (mm), the rotation speed of the right pulley-equipped gear 29R that rotates in accordance with the movement amount X is N (rpm), and the drawing amount of the right wire 30R when the paper stacking base 11 is raised or Displacement of the right tension spring 35R when the winding amount of the right wire 30R when the paper stack 11 is lowered is L (mm) and the displacement amount (deflection amount) of the right tension spring 35R is Y (mm). Since the amount (deflection amount) Y is a difference obtained by subtracting the amount of movement X when the paper stacking table 11 is moved up and down from the amount of drawing or winding L of the wire 30R, the amount of movement X when the paper stacking table 11 is moved up and down. Right tension spring 35R Displacement (bending amount) Y is attributed to the above D1, D2.

この際、上記したＤ１，Ｄ２の関係をＤ１＜Ｄ２＜２Ｄ１とすると、下記の式１〜式４が成立する。 At this time, if the relationship between D1 and D2 is D1 <D2 <2D1, the following formulas 1 to 4 are established.

［数１］
Ｘ＝π×Ｄ１×Ｎ ………式１
［数２］
Ｌ＝π×Ｄ２×Ｎ ………式２
［数３］
Ｙ＝Ｌ−Ｘ＝π×（Ｄ２−Ｄ１）×Ｎ ………式３
［数４］
Ｘ／Ｙ≒Ｄ１／（Ｄ２−Ｄ１） ………式４
尚、式４において、略を示す「≒」の記号は、用紙積載台１１の移動位置により、右側のプーリ付きギア２９Ｒのプーリ部２９ｂのプーリ外周部２９ｂ３と、右側のワイヤ通過用プーリ３２Ｒとの間で右側のワイヤ３０Ｒの他端部側に角度が付いてしまうために用いている。 [Equation 1]
X = π × D1 × N ......... Formula 1
[Equation 2]
L = π × D2 × N ......... Formula 2
[Equation 3]
Y = L−X = π × (D2−D1) × N (3)
[Equation 4]
X / Y ≒ D1 / (D2-D1) ......... Formula 4
In Equation 4, the symbol “≈” indicating the abbreviation indicates the pulley outer peripheral portion 29b3 of the pulley portion 29b of the right pulley gear 29R and the right wire passing pulley 32R depending on the moving position of the paper stacking base 11. It is used because an angle is attached to the other end side of the right wire 30R.

そして、式４において、Ｄ２＝２×Ｄ１の場合にはＸ／Ｙ≒１となり、先に背景技術で説明したと同様に、用紙積載台１１の昇降時の移動量Ｘと左右一対の引張バネ３５Ｌ，３５Ｒの各変位量Ｙとが略同じになるので左右一対の引張バネ３５Ｌ，３５Ｒのバネ長さが長くなり不都合となる。 In Expression 4, when D2 = 2 × D1, X / Y≈1, and as described in the background art, the movement amount X of the sheet stacking table 11 when moving up and down and a pair of left and right tension springs Since the displacement amounts Y of 35L and 35R are substantially the same, the spring length of the pair of left and right tension springs 35L and 35R becomes long, which is inconvenient.

そこで、この実施例では、式４において、Ｄ１＜Ｄ２＜２Ｄ１の条件を満足させることにより、下記の式５が成立する。 Therefore, in this embodiment, the following Expression 5 is established by satisfying the condition of D1 <D2 <2D1 in Expression 4.

［数５］
Ｘ／Ｙ＞１ ………式５
上記した式５から、左右一対の引張バネ３５Ｌ，３５Ｒの各変位量Ｙは、用紙積載台１１の昇降時の移動量Ｘよりも小さく設定できるので、左右一対の引張バネ３５Ｌ，３５Ｒの各バネ長さを短く設定できるために、左右一対の引張バネ３５Ｌ，３５Ｒを用紙積載装置１０又は画像形成装置１内の空きスペースに効率良く設置できるので、用紙積載装置１０又は画像形成装置１を小型化することが可能となる。 [Equation 5]
X / Y> 1 ... Formula 5
Since the displacement amount Y of the pair of left and right tension springs 35L and 35R can be set smaller than the movement amount X when the sheet stacking table 11 is raised and lowered from the above equation 5, each spring of the pair of left and right tension springs 35L and 35R. Since the length can be set short, the pair of left and right tension springs 35L and 35R can be efficiently installed in the empty space in the paper stacking apparatus 10 or the image forming apparatus 1, so the paper stacking apparatus 10 or the image forming apparatus 1 can be downsized. It becomes possible to do.

従って、左右一対のプーリ付きギア２９Ｌ，２９Ｒの各ギア部２９ａの回転に伴って各プーリ部２９ｂのプーリ外周部２９ｂ３から引き出される左右一対のワイヤ３０Ｌ，３０Ｒの引き出し量Ｌ又は各プーリ部２９ｂのプーリ外周部２９ｂ３に巻き取られる左右一対のワイヤ３０Ｌ，３０Ｒの巻き取り量Ｌを、用紙積載台１１の昇降時の移動量Ｘよりも大きく設定して左右一対のワイヤ３０Ｌ，３０Ｒに連結した左右一対の引張バネ３５Ｌ，３５Ｒを変位させることで、用紙積載台１１の昇降時に駆動モータ２４の回転負荷を左右一対の引張バネ３５Ｌ，３５Ｒで確実に補助することができる。 Accordingly, the pulling amount L of the pair of left and right wires 30L and 30R drawn from the pulley outer peripheral portion 29b3 of each pulley portion 29b as the gear portions 29a of the pair of left and right pulley-equipped gears 29L and 29R rotate or the pulley portions 29b The left and right pair of left and right wires 30L and 30R wound around the pulley outer peripheral portion 29b3 is set to be larger than the amount of movement X when the paper stacking table 11 is moved up and down and connected to the left and right pair of wires 30L and 30R. By displacing the pair of tension springs 35L, 35R, the rotational load of the drive motor 24 can be reliably assisted by the pair of left and right tension springs 35L, 35R when the paper stacking base 11 is raised and lowered.

１…画像形成装置、１ａ…側面、１ｂ…開口部、１ｃ，１ｄ…左右の側壁、
１０…用紙積載装置、
１１…用紙積載台、１１ａ…上面、１１ｂ…先端部、１１ｃ…左側面部、
１１ｄ…右側面部、
１２Ｌ，１２Ｒ…左右一対のガイドフェンス、
１３…給紙ローラ、１４…捌きローラ、１６…摩擦板、
２０…昇降機構部、
２１Ｌ，２１Ｒ…左右一対のラック部材、２１ａ…ラック歯、
２２…平板状のブラケット、２３…Ｌ字状のモータブラケット、
２４…回転駆動源（駆動モータ）、２４ａ…モータ軸、２５…ウォームギア、
２６…段付きシャフト、２７…アイドラーギア、
２８Ｌ，２８Ｒ…左右一対の段付きシャフト、
２９Ｌ，２９Ｒ…左右一対のプーリ付きギア、２９ａ…ギア部、２９ｂ…プーリ部、
２９ｂ１…連接用ボス部、２９ｂ２…下フランジ部、２９ｂ３…プーリ外周部、
２９ｂ４…下フランジ部、３０Ｌ，３０Ｒ…左右一対のワイヤ、
３１Ｌ，３１Ｒ…左右一対の段付きシャフト、
３２Ｌ，３２Ｒ…左右一対のワイヤ通過用プーリ、
３３Ｌ，３３Ｒ…左右一対の段付きシャフト、
３４Ｌ，３４Ｒ…左右一対のワイヤ方向転換用プーリ、
３５Ｌ，３５Ｒ…左右一対の引張バネ、３６Ｌ，３６Ｒ…左右一対の固定部、
Ｄ１…左右一対のプーリ付きギアのギア部の直径、
Ｄ２…左右一対のプーリ付きギアのプーリ部のプーリ外周部の直径、
Ｐ…用紙、Ｘ…用紙積載台の昇降時の移動量、Ｙ…引張バネの変位量（撓み量）。 DESCRIPTION OF SYMBOLS 1 ... Image forming apparatus, 1a ... Side surface, 1b ... Opening part, 1c, 1d ... Left and right side wall,
10: Paper stacking device,
11 ... Paper stacking base, 11a ... Upper surface, 11b ... Front end, 11c ... Left side,
11d ... right side surface part,
12L, 12R ... a pair of left and right guide fences,
13 ... paper feed roller, 14 ... rolling roller, 16 ... friction plate,
20: Elevating mechanism,
21L, 21R: a pair of left and right rack members, 21a: rack teeth,
22 ... Flat bracket, 23 ... L-shaped motor bracket,
24 ... Rotation drive source (drive motor), 24a ... Motor shaft, 25 ... Worm gear,
26 ... Stepped shaft, 27 ... Idler gear,
28L, 28R ... a pair of left and right stepped shafts,
29L, 29R: a pair of left and right gears with pulleys, 29a ... gear part, 29b ... pulley part,
29b1 ... connecting boss part, 29b2 ... lower flange part, 29b3 ... pulley outer peripheral part,
29b4 ... lower flange part, 30L, 30R ... a pair of left and right wires,
31L, 31R ... A pair of left and right stepped shafts,
32L, 32R ... A pair of left and right wire passing pulleys,
33L, 33R ... A pair of left and right stepped shafts,
34L, 34R ... A pair of left and right wire direction changing pulleys,
35L, 35R ... a pair of left and right tension springs, 36L, 36R ... a pair of left and right fixing parts,
D1: Diameter of the gear part of the pair of left and right gears with pulleys,
D2: Diameter of the pulley outer periphery of the pulley portion of the pair of left and right gears with pulleys,
P: paper, X: movement amount when the paper stack is raised and lowered, Y: displacement amount (deflection amount) of the tension spring.

Claims

In the paper stacking device installed in the image forming apparatus so that the paper stacking table on which the paper is loaded can be moved up and down via the lifting mechanism,
The lifting mechanism is
A rack attached to the image forming apparatus along a vertical direction;
A gear that meshes with the rack and is rotationally driven by a rotational drive source attached to the paper stacking base to raise and lower the paper stacking base along the rack together with the paper stacking base;
A wire having a pulley outer peripheral portion formed larger in diameter than the diameter of the gear and being rotationally driven coaxially with the gear and having one end fixed to the pulley outer peripheral portion or the vicinity of the pulley outer peripheral portion. A pulley wound in the rotational direction of the gear;
A tension spring in which the other end of the wire is connected to one end and the other end is hooked to the fixed portion;
With
The amount of the wire drawn out from the outer peripheral portion of the pulley with the rotation of the gear or the amount of winding of the wire wound around the outer peripheral portion of the pulley is set larger than the moving amount when the paper stacking table is moved up and down. Then, when the tension spring connected to the wire is displaced , the amount of movement of the paper stacking table when moving up and down is X, and the amount of displacement of the tension spring is Y, the relationship X / Y> 1 is established. sheet stacking apparatus characterized that you set the diameter of the gear and the diameter of the pulley outer periphery as.

The other end side of the wire wound around the pulley outer periphery is changed in the paper width direction orthogonal to the paper transport direction via a wire direction changing pulley, and the other end side of the wire is changed. sheet stacking apparatus according to claim 1, characterized in Rukoto is connected to one end of the tension spring which is placed along the sheet width direction.