JP2005008392A - Separation member, feeding device for sheet material, and image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a separation member capable of improving separation performance of sheet materials, a feeding device for sheet material having it, and an image forming device having them. <P>SOLUTION: This separation member has a plurality of abutting faces arranged opposingly on a feeding means for feeding sheet material from a sheet material loading member to separate sheet materials fed from the sheet material loading member by the feeding means one by one between the feeding device and it in the direction S of feeding of the sheet material as shown by marks 6b, 6b', 6b". The feeding device for sheet material having it and the image forming device having them are provided. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

【００５２】
ここで以上に示した数式の各変数に実際の値を代入して本願によるシート材分離方法と一般的な従来の分離パッドを用いたシート材分離方法とを対比する。なお、シート材間摩擦係数の差Δμ_ｐの値としては裏紙使用時も考慮して３水準を用いた。以下の表２に各変数の代入値の一例を示す。
【００５３】
【表２】

【００５４】
図１４は、縦軸に給紙圧Ｐ、横軸に分離圧Ｑをとってこの発明によるシート材の給送方法での上述のＮＦ斜面：（３）式，ＭＦ斜面：（４）式，ＮＦニップ：（１１）式，ＭＦニップ：（１２）式のそれぞれから求めた境界線を示した線図である。なお、ＭＦ境界線に関しては３水準のΔμ_ｐに対応して３本示している。また、分離パッドを用いたＦＰ分離方法に関しても３水準のΔμ_ｐに対応したＭＦ境界線を示している。さらに参考として、この発明を実施した給紙装置のＰ．Ｑ設定領域も示してある。また、給紙圧及び分離圧は、バネ秤や圧力センサ等の手段により測定することができる。測定の際には、シート材の重量を考慮するとなお好ましい。
【００５５】
この図１４から分かるように、裏紙用紙の継ぎ足しを想定したシート材間の摩擦係数の差Δμ_ｐ＝０．２ではＦＰ分離方法の重送領域はかなり狹まり、一般的なＰ−Ｑ設定では対応できない。これに対し、本願のシート材分離方法ではΔμ_ｐ＝０．２でも重送域までかなりの余裕がある。
【００５６】
次式（２１）はＦＰ分離方法でのＭＦ境界線を示すものである。
Ｐ＜（μ_ＦＰ−μ_ｐ１２）Ｑ／Δμ_ｐ （２１）
これに対し、本願のシート材分離方法でのＭＦ境界線の傾きは（１５）式から
｛（Ａ／Ｂ）−μ_ｐ１２｝／Δμ_ｐ
である。これから、本分離方法におけるＦＰ摩擦係数μ_ＦＰに相当する値がＡ／Ｂであることが分かる。これは、シート材先端に作用する力の分力を決定する係数であり、表２に示す各変数の設定例では（５）式及び（８）式から
Ａ／Ｂ＝１．４ （２２）
であって見かけ上μ_ＦＰが１．４であることと等価となる。このことが本願シート材分離方法がＦＰ分離方法よりもはるかに広い重層余裕度が得られる要因であると考えられる。この場合、本願とＦＰ分離方法の重送境界線の傾きの比は次のようになる。
｛（Ａ／Ｂ）−μ_ｐ１２｝／（μ_ＦＰ−μ_ｐ１２）≒４．１ （２３）
このように、本願の重送余裕度はＦＰ分離方法の約４倍の大きさを有している。
【００５７】
さらに、シート材の１枚目と２枚目の間の摩擦係数μ_ｐ１２が大きな値となるラグ紙（ボンド紙）や再生紙の場合の重送余裕度を確認するため、μ_ｐ１２＝０．７７，Δμ_ｐ＝０．２の場合のＰ−Ｑ線図を図１５に示す。この図１５から、給紙圧Ｐが充分に得られれば本願のシート材分離方法によりシート材間の摩擦係数が高い裏紙でも分離可能であることが分かる。
【００５８】
次に、図１６は、上記の傾斜部材６の傾斜面６ａとシート材２の繰り出し方向とのなす角度（θ_２）を５０°から７０°に振った場合の重送ＭＦ領域と不送りＮＦ領域とを実験データに基づいて縦軸に給紙圧Ｐ、横軸に分離圧Ｑをとって示す図１４と同様の線図である。この図１６から明らかなように、四角実線で示した設定領域でシート材間の摩擦係数の差Δμ_ｐ＝０．２まで対応可能となる。ただし、上記の角度θ_２を７０°に設定した場合には不送りＮＦ領域が厳しくなるが、同図１６で四角破線で示した設定領域θ_２＝７０°等の分離圧／給紙圧を対応させれば充分に設定可能となる。
【００５９】
また、図１７は、前述の条件式から求めた厚紙Ａ不送り（ＮＦ）領域と実測値とを比較した線図であり、厚紙Ａ不送りＮＦ領域においては、μ_１＝１．３，μ_ｐ＝０．６７にて近似し、薄紙Ｂ重送ＭＦ領域ではμ_２′＝０．１５，μ_ｐ＝０．５４，Δμ_ｐ＝０．０４８にて近似することが実測により確認されている。なお、その他の代入値及び厚紙Ａ及び薄紙Ｂの傾斜面からの垂直抗力Ｒ_ｆの値は前述の表１及び表２と同値である。このように、各条件式に別途測定した摩擦係数データを入力することにより実測値と近似することが判明し、上記各条件式の有効性を証明することができた。
【００６０】
このような構成からなるシート材の給送装置において、傾斜部材６は複雑な形状をしているため、合成樹脂により一体成形するのが好ましい。その場合、図１８及び図１９に示すように、傾斜部材６の当接面６ｂの長さＡが給送ローラ４の軸線方向の長さＢより大きいと、図示しないシート材の搬送時に給送ローラ４の方向に押圧されてシート材に摺接している傾斜部材６の当接面６ｂは、その中央部に分離圧がかかっているため、シート材を介して給送ローラ４に押圧されている当接面６ｂの中央部だけが摩耗して陥没する。
【００６１】
傾斜部材６がこのように変形すると、シート材が給送ローラ４と傾斜部材６の間に進入する際、そのシート材は傾斜部材６の変形した当接面６ｂにならって湾曲しながら給紙される。そのため、シート材の搬送負荷が著しく大きくなったり、剛性の強いシート材では湾曲不能となったりして不送りが発生する。よって、図５に示したように、傾斜部材６の当接面６ｂの長さを給送ローラ４の軸線方向の長さより小さくして、当接面６ｂの全長が常時給送ローラ４に当接可能としている。
【００６２】
このような構成によれば、傾斜部材６の当接面６ｂは全長に亘ってシート材を介して給送ローラ４に押圧されているため、当接面６ｂに部分的な陥没部が形成されるおそれはなく、当接面６ｂは直線状に平均して摩耗する結果となる。そして、この傾斜部材６は給送ローラ４の方向に平行移動するため、当接面６ｂに摩耗が生じてもシート材の搬送方向Ｓに対して傾斜部材６の傾斜面６ａは所定の角度を保つことが可能である。
【００６３】
度重なる実験の結果から、この実施形態において、シート材２の良好な分離を行うための条件は、図２０に示すように、給送ローラ４に押圧する底板１上のシート材２の圧接部位Ｘと、給送ローラ４に押圧する傾斜部材６の圧接部位Ｎとのシート材繰り出し方向の距離Ｋを２〜６ｍｍにし、繰り出されるシート材２の繰り出し方向Ｓに対して傾斜部材６の傾斜面６ａのなす角度θ_２を５０°〜７０°にするとよいことが判った。
【００６４】
このようにすれば、給送ローラ４が通常使用される大きさ、例えばφ１６〜３６ｍｍの範囲にある限り、傾斜面６ａにおいて、給送ローラ４によって底板１から繰り出された複数枚のシート材２のプレ分離すなわち、シート材２ａとこれより開のシート材２ｂ等とのずらしによる分離が行われ、さらに上述の当接面６ｂにて分離が行われることで、常に良好な分離品質が得られることが確認された。
【００６５】
以上、図６ないし図２０を参照して、底板１上に積載されたシート材２、給送ローラ４及び傾斜部材６の関係をモデル化して詳細に説明した。モデル化のため、傾斜部材６は、凸部６１のみを有することとして説明した。しかし、凸部６１のみを有する場合には、角度θ_２などの種々の条件を上述のようにしても、シート材の製造工程における切断工程においてバリが生じたシート材を給送する場合など、シート材相互間などの摩擦係数μが想定した以上に高くなったときは、複数枚のシート材２が傾斜面６ａを乗り越えてシート材の重送が生じることに対する余裕度が低くなる場合があり、図２２に示すように、シート材２の重送の発生が否定できない。
【００６６】
そこで、本発明にかかる傾斜部材６は、分離性能をさらに向上させるため、モデル化したときの傾斜部材６すなわち凸部６１のみを有する傾斜部材６と異なり、複数の凸部６１、６１’、６１”を有している。したがって、図２１に示すように、複数枚のシート材２が凸部６１を乗り越えた場合であっても、凸部６１より方向Ｓの下流側に位置する凸部６１’、６１”により、最上位のシート材２ａのみが分離され、重送が防止されて、一枚のシート材２ａのみが搬送ローラ対７により画像形成部３４に送られる。
【００６７】
ここで、凸部６１、６１’、６１”はそれぞれ、角度θ_２などの種々の条件を上述のようにしているため、各々が良好なプレ分離性能等の良好な分離性能を有している。また、凸部６１の当接面６ｂの長さを給送ローラ４の軸線方向の長さより小さくして、当接面６ｂの全長が常時給送ローラ４に当接可能としたことはすでに述べたが、これは凸部６１’における当接面６ｂ’、凸部６１”における当接面６ｂ”についても同様としている。
【００６８】
画像形成装置３０は以上のような構成であるから、画像形成装置本体３１内に設けた光学読取系３２により読み取った画像データ等を基にして、書き込み装置３３が画像形成部３４に備えられている、帯電装置５６によって帯電された感光体ドラム３５上に潜像を形成し、その潜像を画像形成部３４に備えられた現像装置３６がトナーにより可視像とする。
【００６９】
給送装置１００のカセット１１から底板１上に積載されたシート材２が給送ローラ４により給送され、傾斜部材６との共働によりシート材２は１枚ずつ良好に分離され、１枚のシート材２のみが搬送ローラ対７によって搬送路３７を通して画像形成部３４に搬送され、感光体ドラム３５上の可視像が転写装置５９によりそのシート材２上に転写される。転写後の感光体ドラム３５はクリーニング装置５０によりクリーニングされ、再度、帯電装置５６による帯電に供される。
【００７０】
トナー像を転写されたシート材２は定着装置３８に搬送されて定着が行われ、排紙分岐爪５１を経て排紙ローラ対３９に搬送されたときには排紙ローラ対３９により外部の排紙トレイ４０に排出される。両面画像形成時には、シート材２は排紙分岐爪５１により反転搬送路４１から両面装置４２へ向けて搬送され、両面トレイ４３に一旦格納された後に進行方向を逆転し、両面搬送路４４から再び画像形成部３４に送り込まれて裏面に画像が形成され、定着装置３８、排紙分岐爪５１、排紙ローラ対３９を通って排紙トレイ４０上に排出される。
【００７１】
以上、本実施形態を説明したが、本発明を適用可能な範囲において、実施形態は上述の態様に限らず他の態様をとることができる。たとえば、図１においては、図面を簡略化するため、給送装置１００を１個のみ示したが、必要に応じてサイズの異なる複数個の給紙装置を設けることも可能である。この場合、何れのシート材の給送装置にも本発明を適用可能であり、本発明を適用した分離部材を用いることができる。給送手段は給紙ローラでなく、ベルト状の給紙ベルトであっても良い。
【００７２】
当接部は、方向Ｓにおいて複数配設すればよく、３つに限るものではない。傾斜部は、複数の凸部のうち、少なくとも、方向Ｓにおける最上流の凸部に形成すればよい。最上流の傾斜部にシート材の先端が最初に当接するため、プレ分離性能が最も要求されるからである。最上流の傾斜部は、シート材の幅方向における中央部に設けるに限らないが、シート材のスキューを防止する観点から同幅方向中央に関して対称に設けることが望ましく、本実施形態のように中央部に設ければ、最上流の凸部が１つで済むため、凸部全体の数を抑制できる点で好ましい。
【００７３】
本実施形態においては、下流側の当接面は、シート材の幅方向において、上流側の当接面と重ならない態様で異なる位置に設けたが、上流側の当接面と一部重なりずれた態様で異なる位置に設けても良い。上流側の当接面と給送手段との間では、その凸部を乗り越えた複数のシート材は密に挟みつけられているが、シート材の幅方向において上流側の当接面とずれた位置においては、シート材はその自重により給送手段や他のシート材から離間した位置を占める傾向にあり、したがって上流側の当接面と異なる位置に設けられた下流側の凸部は、その分離性能が向上するからである。
【００７４】
【発明の効果】
本発明は、シート材積載部材からシート材を送り出す給送手段に対向配置され、同給送手段との間で、同給送手段によってシート材積載部材から送り出されたシート材を一枚ずつ分離するための当接面を有する分離部材であって、上記当接面を、シート材の送り方向において複数有するので、複数枚のシート材がシート材の送り方向上流側の当接面を乗り越えても下流側の当接面によりシート材を一枚だけ分離するので、シート材のバリが大きいこと等により摩擦係数が極めて大きいときであっても、シート材の分離性能が向上しているから、シート材の重送を確実に防止して、シート材を一枚のみ給送することに寄与できる分離部材を提供することができる。
【００７５】
シート材積載部材から送り出されたシート材の先端が係合する、シート材の送り方向に対して傾斜した傾斜面を有し、この傾斜面を、上記当接面のうち少なくとも上記送り方向における最上流側の当接面の、同送り方向における上流側に配設したこととすれば、傾斜面によりプレ分離を行うことで、複数枚のシート材がシート材の送り方向上流側の当接面を乗り越えることを防止し、かりに乗り越えても下流側の当接面によりシート材を一枚だけ分離するので、シート材のバリが大きいこと等により摩擦係数が極めて大きいときであっても、シート材の分離性能がより向上しているから、シート材の重送をより確実に防止して、シート材を一枚のみ給送することに寄与できる分離部材を提供することができる。
【００７６】
当接面のうちシート材の送り方向における最上流側の当接面を、シート材の幅方向における中央部に配設したこととすれば、当接面の数を抑制した比較的簡易な形状で、シート材のスキューを防止しつつシート材の重送防止に寄与できる分離部材を提供することができる。
【００７７】
当接面のうち、シート材の送り方向における下流側の当接面を、この当接面より上流側の当接面のシート材の幅方向における位置と異なる位置に配設したこととすれば、シート材の送り方向下流側の当接面が分離に適した位置を占めるので、複数枚のシート材がシート材の送り方向上流側の当接面を乗り越えても、下流側の当接面による分離性能が向上しているため、下流側の当接面により確実にシート材を一枚だけ分離でき、シート材のバリが大きいこと等により摩擦係数が極めて大きいときであっても、シート材の分離性能がさらに向上しているから、シート材の重送をさらに確実に防止して、シート材を一枚のみ給送することに寄与できる分離部材を提供することができる。
【００７８】
本発明は、シート材を積載するシート材積載部材と、このシート材積載部材に積載されたシート材に係合し同シート材を送り出す給送手段と、この給送手段によって上記シート材積載部材から送り出されたシート材を一枚ずつ分離するための、請求項１ないし３の何れか１つに記載の分離部材とを有するシート材の給送装置にあるので、上述の各効果を奏する分離部材を有し、複数枚のシート材がシート材の送り方向上流側の当接面を乗り越えても下流側の当接面によりシート材を一枚だけ分離するので、シート材のバリが大きいこと等により摩擦係数が極めて大きいときであっても、シート材の分離性能が向上しているから、シート材の重送を確実に防止して、シート材を一枚のみ給送することができるシート材の給送装置を提供することができる。
【００７９】
請求項６記載の発明は、請求項１ないし４の何れか１つに記載の分離部材、または、請求項５記載のシート材の給送装置を有する画像形成装置にあるので、上述の各効果を奏する分離部材またはシート材の給送装置を有し、複数枚のシート材がシート材の送り方向上流側の当接面を乗り越えても下流側の当接面によりシート材を一枚だけ分離するので、シート材のバリが大きいこと等により摩擦係数が極めて大きいときであっても、シート材の分離性能が向上しているから、シート材の重送を確実に防止して、シート材を一枚のみ給送することができ、バリが大きいこと等により摩擦係数が極めて大きなシート材に対しても画像形成を良好に行うことができる画像形成装置を提供することができる。
【図面の簡単な説明】
【図１】本発明を適用した分離部材、これを有するシート材の給送装置及びこれらを有する画像形成装置の概略構成を示す縦断面図である。
【図２】図１に示したシート材の給送装置の要部の縦断面図である。
【図３】図１に示したシート材の給送装置の分解斜視図である。
【図４】図１に示した分離部材の拡大斜視図であるである。
【図５】図１に示した分離部材の斜視図であるとともに図１に示したシート材の給送装置の要部の分解斜視図である。
【図６】図２に示したシート材の給送装置をモデル化したものの一部を拡大して示す説明図である。
【図７】図６に示したシート材の給送装置において最上位のシート材の力関係を示す説明図である。
【図８】図６に示したシート材の給送装置において最上位のシート材の下にあるシート材の力関係を示す説明図である。
【図９】図６に示したシート材の給送装置において傾斜部材の摩耗状態を示す説明図である。
【図１０】図６に示したシート材の給送装置において分離部を拡大して示す説明図である。
【図１１】図６に示したシート材の給送装置においてニップ直前のシート材先端に作用する力関係を示す説明図である。
【図１２】図６に示したシート材の給送装置においてニップ進入時のシート材先端に作用する力関係を示す説明図である。
【図１３】先端集中荷重による梁の撓み状態を示す説明図である。
【図１４】図６に示したシート材の給送装置によるシート材の分離方法の一例を、従来のシート材の給送装置によるシート材の摩擦分離方法と比較して示す線図である。
【図１５】図６に示したシート材の給送装置によるシート材の分離方法の一例を、従来のシート材の給送装置によるシート材の摩擦分離方法と比較して示す他の例の線図である。
【図１６】図６に示したシート材の給送装置において傾斜面にシート材の繰り出し方向の先端が突き当たる時の角度を５０°から７０°に振った場合の設定領域を例示する線図である。
【図１７】図１６と同様の状態で厚さの異なるシート材の不送り領域と重送領域とを実測定と条件式とで比較した線図である。
【図１８】給送ローラと傾斜部材との給送ローラの軸方向における長さの関係を示す比較例の分解斜視図である。
【図１９】給送ローラと傾斜部材との給送ローラの軸方向における長さの関係を示す給送ローラと傾斜部材との比較例の横断面図である。
【図２０】図６に示したシート材の給送装置において給送ローラと傾斜部材との関係を示す説明図である。
【図２１】本発明を適用した分離部材により、最上位のシート材が一枚だけ分離して給送される様子を示す模式図である。
【図２２】複数枚のシート材が従来の分離部材を乗り越えた様子を示す模式図である。
【符号の説明】
１ シート材積載部材
２ シート材
４ 給送手段
６ 分離部材
６ａ、６ａ’、６ａ” 傾斜面
６ｂ、６ｂ’、６ｂ” 当接面
６ｂ 最上流側の当接面
６ｂ 上流側の当接面
６ｂ’、６ｂ” 下流側の当接面
３０ 画像形成装置
Ｓ シート材の送り方向[0001]
BACKGROUND OF THE INVENTION
The present invention includes a separating member for separating and feeding only one uppermost sheet material among the sheet materials stacked on the sheet material stacking member, a sheet material feeding apparatus including the separation member, and the like. The present invention relates to an image forming apparatus.
[0002]
[Prior art]
In general, a copying machine such as a digital copying machine, a facsimile such as plain paper facsimile, a printer such as a laser beam printer and an inkjet printer, a printing machine such as a stencil printing machine, and an image forming apparatus such as an ATM are generally sheet-like recording media. An image using toner, ink, or the like is formed on a sheet material such as an image forming unit configured to include an image carrier such as a photoreceptor.
[0003]
Therefore, the image forming apparatus generally includes a sheet material stacking member such as a paper feed tray capable of stacking a plurality of sheet materials, and feeds the sheet material stacked on the sheet material stack member toward the image forming unit. A sheet material feeding device is provided. In such a sheet material feeding device, it is important to feed the sheet materials stacked on the sheet feeding tray one by one toward the image forming unit. For this reason, the sheet material feeding device is loaded. The sheet material is separated one by one from the uppermost sheet material positioned at the top and fed to the image forming unit.
[0004]
Conventionally, as such a configuration, a corner claw separation method in which both ends in the width direction at the front end of the sheet material feeding direction are pressed and separated by a claw member, a separation pad method in which a sheet material is separated by pressing a friction member, and a sheet material In general, a configuration using a bank separation method or the like that abuts against a fixed gate member having an inclined surface and separates it is known.
[0005]
Among these configurations, there is a sheet material separation method that can be applied to a wide variety of sheet materials (for example, postcards, envelopes, OHP paper, etc.) including the same configuration and different sizes of cardboard and thin paper at a low cost with a small number of parts. As a configuration to be used, there is a configuration using a well-known separation pad method, or a configuration using a bank separation method as disclosed in, for example, [Patent Document 1].
[0006]
[Patent Document 1]
JP-A-8-91612 gazette
[Problems to be solved by the invention]
However, in the conventional sheet feeding method and apparatus using such a separation method, the former separation pad method is particularly low-priced 10 PPM (image forming speed is 10 sheets per minute) or less. In the case of the low-speed machine, since the noise caused by the sticking slip is generated during conveyance by the sheet material held between the feeding roller and the friction member, it is necessary to take measures to make the feeding roller a half-moon shape.
[0008]
Therefore, it is necessary to provide a pair of cylindrical collars slightly smaller in diameter than the feed roller diameter to limit the rise of the sheet material stacking member on both sides of the feed roller coaxially with the feed roller. As a result, the production cost increases as the score increases. Recently, as the use of recycled paper has increased, the leading edge of the sheet material such as postcards, envelopes, etc. has fluttered, and burrs have occurred during cutting. Therefore, the separation pad method also has a problem that non-feeding of the sheet material is likely to occur.
[0009]
In addition, the use of backing paper is increasing due to the reuse of copy paper, and there is a risk that the friction coefficient between the stacked sheet materials will increase and double feed may occur. As a result, the sheet material is curled, and depending on the curl direction, a load may be generated at the leading edge of the sheet material in the separation portion of the sheet material, or the sheet material may not be conveyed to the separation portion and may not be fed.
[0010]
In the case of the separation pad method, since the flat portion of the pad is pressed by the feeding roller, the sheet material is fed out of the stacked state in the conveyance direction (corresponding to the displacement angle of the sheet material stacking member such as the bottom plate). Therefore, the angle of the separation pad must be within a predetermined range. For this purpose, the roller diameter of the feeding roller is limited, and the size of the feeding device cannot be reduced due to restrictions on the freedom of layout. There is also a problem.
[0011]
On the other hand, in the case of the latter bank separation method, what is shown in [Patent Document 1] is that the upper edge portion of the inclined member in contact with the feeding roller is flat and the nip portion with the feeding roller is wide, It becomes difficult to dispose the inclined surface at a predetermined inclination angle due to variations in the above. Further, normally, when the uppermost sheet material is conveyed in the image forming unit, the driving of the feeding roller is cut off, but while the preceding sheet material is nipped between the feeding roller and the gate member, The feeding roller is rotated by the frictional force with the sheet material. When the trailing edge of the preceding sheet material passes through the nip portion, the leading edge of the next sheet material is fed to the inclined member by the rotation of the feeding roller. It is done. At this time, the friction coefficient between the sheet materials is high or varies widely, and the friction coefficient between the next sheet material and the next sheet material is greater than the friction coefficient between the preceding sheet material and the next sheet material. If it is low, the next sheet material may get over the inclined member, which may cause double feeding.
[0012]
In order to solve the above-mentioned problems, the applicant of the present invention has greatly reduced the influence of the bending elastic modulus of a wide variety of sheet materials with a simple configuration, without causing various sheet materials to be unfed or double-fed. A sheet material feeding apparatus for separating and feeding one sheet at a time was developed and applied (Japanese Patent Application No. 2001-217675, etc.). Such a prior application uses a separating member having an inclined surface against which the leading edge of the sheet material abuts when separating the sheet material, and the sheet material sent from the sheet material stacking member by a paper feed roller or the like is inclined before entering the nip portion. The present invention relates to a separation method that performs pre-separation.
[0013]
However, even with the technique disclosed in the prior application, a plurality of sheet materials may get over the inclined surface, and the sheet materials may be double-fed. In particular, in the sheet material in which burrs are generated in the cutting process in the manufacturing process of the sheet material, the friction coefficient between the sheet materials becomes high, and a plurality of sheet materials overcome the inclined surface and the sheet material is double-fed. Low margin. For this reason, it is necessary to further improve the separation performance.
[0014]
An object of the present invention is to provide a separation member with improved sheet material separation performance, a sheet material feeding apparatus having the separation member, and an image forming apparatus having these.
[0015]
[Means for Solving the Problems]
The invention described in claim 1 is arranged opposite to the feeding unit that feeds the sheet material from the sheet material stacking member, and the sheet material fed from the sheet material stacking member by the feeding unit to and from the feeding unit. A separation member having a contact surface for separating one by one, wherein a plurality of the contact surfaces are provided in a sheet material feeding direction.
[0016]
The invention according to claim 2 has an inclined surface inclined with respect to the feeding direction of the sheet material with which the leading edge of the sheet material fed from the sheet material stacking member is engaged in the separation member according to claim 1, The inclined surface is arranged at least upstream of the contact surface on the most upstream side in the feed direction in the feed direction.
[0017]
According to a third aspect of the present invention, in the separation member according to the first or second aspect, the contact surface on the most upstream side in the feeding direction among the contact surfaces is disposed at a central portion in the width direction of the sheet material. It is characterized by that.
[0018]
According to a fourth aspect of the present invention, in the separation member according to any one of the first to third aspects, the contact surface on the downstream side in the feed direction is the upstream of the contact surface. The contact surface on the side is disposed at a position different from the position in the width direction of the sheet material.
[0019]
According to a fifth aspect of the present invention, there is provided a sheet material stacking member for stacking the sheet material, a feeding unit that engages with the sheet material stacked on the sheet material stacking member and feeds the sheet material, and the feeding unit A sheet material feeding device having a separating member according to any one of claims 1 to 4 for separating sheet materials fed from a sheet material stacking member one by one.
[0020]
According to a sixth aspect of the present invention, there is provided an image forming apparatus comprising the separation member according to any one of the first to fourth aspects or the sheet material feeding device according to the fifth aspect.
[0021]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 shows a separating member according to an embodiment to which the present invention is applied, a sheet material feeding apparatus having the separating member, and an image forming apparatus having these, and the image forming apparatus shown in FIG. The structure of is shown. The image forming apparatus may be another copying machine, a facsimile machine such as a plain paper facsimile machine, a printer such as a laser beam printer or an ink jet printer, a printing machine such as a stencil printing machine, an ATM, or the like. The image forming apparatus 30 forms a single color image, but may be capable of forming a color image. The image forming apparatus 30 can use a special sheet such as a thick paper or an OHP sheet in addition to plain paper as the sheet material 2 as a sheet-like recording medium.
[0022]
The image forming apparatus 30 includes a document reading unit 32 as an optical reading system, a writing device 33 as an optical writing system, and an image forming unit 34 as an image printing unit as an image forming system from above the image forming apparatus main body 31. And a double-sided device 42 that reverses the sheet material 2 on which the toner image is formed on one side in the image forming unit 34 when the image is formed on both sides of the sheet material 2 and sends the image to the image forming unit 34 again. And a feeding device 100 as a feeding device.
[0023]
The image forming unit 34 includes a photosensitive drum 35 as an image carrier that is a drum-like latent image carrier, and the photosensitive drum 35 is rotated clockwise in FIG. 1 by a driving source (not shown). Around the photosensitive drum 35, a charging device 56, a developing device 36, a transfer device 59, and a cleaning device 50 for performing an electrophotographic copying process along the rotational direction are arranged.
[0024]
The image forming apparatus 30 includes a fixing device 38 that is disposed on the downstream side of the transfer device 59 in the conveyance path of the sheet material 2 indicated by reference numeral 37 and fixes the toner image on the sheet material 2 to the sheet material 2. The sheet material 2 on which the toner image is fixed by the sheet 38 is discharged to the outside of the image forming apparatus 31 or discharged to the double-sided apparatus 42, and the toner image is fixed by the fixing apparatus 38. A sheet discharge roller pair 39 for discharging the sheet material 2 to the outside of the image forming apparatus main body 31 and a sheet discharge tray on which the sheet material 2 disposed outside the image forming apparatus main body 31 and discharged by the sheet discharge roller pair 39 is stacked. 40.
[0025]
Although not shown, the original reading unit 32 is equipped with a light source for scanning the original placed on the original placement table and an optical path conversion reflecting mirror, and the reflected light from the original is read via the reading optical system. The light is incident on an optical element such as a CCD, and is output to a control unit (not shown) as image information which is image data of a document by the optical element. The writing device 33 is connected to the polygon mirror 33A via a semiconductor laser (not shown) that performs irradiation in accordance with image information and the like of the document input to the control unit, and a reflecting mirror and an imaging lens (not shown) that form an imaging optical system. Is applied to the photosensitive drum 5 to form an electrostatic latent image.
[0026]
The semiconductor laser is controlled to emit light based on the image signal from the control unit. In the control unit, not only the image information from the document reading unit 32 but also the print signal and the facsimile apparatus when used as a printer. The drive control of the semiconductor laser is performed by an image signal corresponding to the transmission signal when used as a semiconductor device. Here, the image forming apparatus 30 is not only a copying machine but also a digital multifunction machine having functions as a printer and a facsimile machine.
[0027]
The reversing device 42 includes a reverse conveyance path 41 that is a path through which the sheet material 2 enters by branching by the paper discharge branch claw 51, a double-sided tray 43 that stacks the sheet material 2 conveyed through the reverse conveyance path 41, A double-sided conveyance path 44 that is a path for feeding the sheet material 2 from the tray 43 toward the image forming unit 34 is provided.
[0028]
The feeding device 100 stacks the sheet material 2 and supplies the stacked sheet material 2 to the image forming unit 34. As shown in FIG. 2 or FIG. 3, the feeding device 100 is detachably mounted through a shallow bowl-shaped device main body 10 having a wall surface having a low height on all four sides, and an opening 10 b on the side surface of the device main body 10. Cassette 11. In this cassette 11, a bottom plate 1 which is a sheet material stacking member capable of stacking a plurality of sheet materials 2 is supported at one end by a support shaft 1a so as to be freely slidable, and is a compression spring engaged with the cassette 11. 3, the free end is always urged upward in FIG.
[0029]
The apparatus main body 10 is a feeding means that can be brought into pressure contact with the leading end portion of the uppermost sheet material 2a of the sheet material 2 stacked on the bottom plate 1 urged counterclockwise in FIG. It has a feeding roller 4 as a separation roller as means, and an inclined member 6 as a separation member pressed against the feeding roller 4 by the urging force of a compression spring 5. The feeding roller 4 and the inclined member 6 constitute a separation unit for separating the sheet material 2 one by one and feeding it to the image forming unit 34. The bottom plate 1 is slidably supported by the support shaft 1 a and urged by the compression spring 3, so that the uppermost sheet material 2 a among the stacked sheet materials 2 is fed to the feeding roller 4. It can be tilted so as to be brought into pressure contact with each other.
[0030]
As shown in FIG. 4, the inclined member 6 has convex portions 61, 61 ′, 61 ″ that are a plurality of separating means protruding from a plane 60 that forms the upper surface. The convex portions 61, 61 ′, Reference numerals 61 ″ denote inclined surfaces 6a, 6a ′, 6a ″ inclined with respect to the feeding direction S of the sheet material 2 which are engaged when the leading end of the sheet material 2 fed from the bottom plate 1 abuts against the feeding roller 4. And a plurality of contact surfaces 6b, 6b for separating the sheet material 2 fed from the bottom plate 1 by the feed roller 4 one by one between the feed roller 4 and the feed roller 4. ', 6b ". The inclined surfaces 6a, 6a ′, 6a ″ are respectively located upstream of the contact surfaces 6b, 6b ′, 6b ″ in the direction S. The contact surfaces 6 b, 6 b ′, 6 b ″ can be pressed against the feeding roller 4 by the urging force of the compression spring 5.
[0031]
Each of the inclined surfaces 6a, 6a ′, 6a ″ is planar, and each of the convex portions 61, 61 ′, 61 ″ is perpendicular to the axial direction of the sheet feeding roller 4, that is, the width direction of the sheet material 2, In other words, the same shape is obtained even in a cross section parallel to the paper surface of FIG. Such a cross section is a plane parallel to the feeding direction S of the sheet material 2 and perpendicular to the image forming surface of the sheet material 2.
[0032]
Of the convex portions 61, 61 ′, 61 ″, the convex portion 61 is located on the most upstream side in the direction S, and the convex portions 61 ′, 61 ″ are located on the downstream side in the direction S from the convex portion 61. is doing. The convex portions 61 ′ and 61 ″ occupy the same position in the direction S and have the same shape. The contact surface 6 b, in other words, the convex portion 61 is disposed at the central portion in the width direction of the sheet material 2. The contact surfaces 6b ′ and 6b ″, in other words, the convex portions 61 ′ and 61 ″ are different from the arrangement positions of the convex portions 61 in the width direction of the sheet material 2, specifically, the arrangement of the convex portions 61. It is arranged on both sides of the installation position.
[0033]
As shown in FIGS. 3 to 5, the inclined member 6 has pins 6 d and 6 d protruding from the left and right side surfaces, and the pins 6 d and 6 d are guided by the grooves 8 and 8 on the apparatus body 10 side. The feed roller 4 is mounted so as to be able to move in parallel in the direction of pressure contact. The inclined member 6 has a pair of four hooks 6f for preventing it from being extended at the lower part, and the hook 6f engages with a locking portion (not shown) of the apparatus main body 10 so that the rising limit is restricted. In FIG. 3, only two hooks 6f are shown.
[0034]
As shown in FIGS. 1 to 3, on the downstream side of the inclined member 6 in the conveyance direction of the sheet material 2, a pair of conveyance rollers 7 (for conveying the sheet material 2 fed by the feeding roller 4 to the image forming unit 34 ( FIG. 3 shows only one) which is rotatably supported. The parallel movement means of the inclined member 6 may be provided with a groove on the inclined member 6 side and a pin on the apparatus main body 10 side.
[0035]
Here, with reference to FIGS. 6 to 20, the relationship among the sheet material 2, the feeding roller 4, and the inclined member 6 stacked on the bottom plate 1 will be described in detail. The inclined member 6 actually has three convex portions 61, 61 ′, 61 ″ as already described. However, for the sake of modeling here, the inclined member 6 has only one convex portion 61. Note that the portions other than the modeled configuration are described as the configuration of the present embodiment.
[0036]
The contact surface 6b that contacts the feeding roller 4 that is continuous with the inclined surface 6a is formed as a ridge along the axial direction of the feeding roller 4, and its width is extremely large. In addition, such a protrusion may consist of one continuous line or may consist of a plurality of intermittent lines. Pressure contact between the feeding roller 4 and the inclined surface end 6c where the pressure contact portion X of the uppermost sheet material 2a on the bottom plate 1 that is in pressure contact with the feeding roller 4 intersects the inclined surface 6a of the inclined member 6 and the contact surface 6b. When a sheet feeding start signal is issued from a control unit (not shown) so that the distance along the sheet material feeding direction S with the nip forming portion N that is a part is as close as possible, the feeding of the uppermost sheet material 2a is performed. The feed roller 4 can be rotated until the end.
[0037]
In this way, by reducing the distance between the pressure contact parts X and N, the bending range at the leading end of the sheet material becomes large even in various sheet materials having different bending elastic coefficients, and therefore the bending elastic coefficients are close to each other. Further, variation in the component force generated on the inclined surface 6a of the inclined member 6 is suppressed, and it is possible to separate sheet materials such as thin paper having a small bending elastic modulus, not to mention cardboard, postcard, and envelope having a large bending elastic coefficient. It can be used for a wide variety of sheet materials.
[0038]
The operation of the above configuration will be described with reference to FIGS. FIG. 7 shows the force relationship of the uppermost sheet material 2a. As the force for feeding a plurality of stacked sheet materials 2 to the separating section by the feeding roller 4, the leading edge of the uppermost sheet material 2a is used. A force F acts on the inclined surface 6 a of the inclined member 6. The inclined surface 6a is set to be an angle theta ₂ with respect to the feeding direction S of the uppermost of the sheet material 2a, the component force F1 in a direction perpendicular to the inclined surface 6a, in the direction along the inclined surface 6a A component force F2 is generated.
[0039]
Further, the separation pressure Q of the compression spring 5 that presses the inclined member 6 against the feeding roller 4 is set at a predetermined angle θ ₁ with respect to the feeding direction S of the sheet material 2, and this separation pressure Q is set to the above-described amount. By setting it smaller than the α component F1α of the force F1, the uppermost sheet material 2a gets over the inclined surface 6a of the inclined member 6 and is fed in the direction of the conveying roller pair 7 shown in FIG.
[0040]
FIG. 8 shows the force relationship of the next sheet material 2b. A force Fp acts on the next sheet material 2b due to a frictional load with the next sheet material 2c, and this force Fp is inclined. A component force Fp1 perpendicular to the inclined surface 6a of the member 6 and a component force Fp2 along the inclined surface 6a are generated. However, since the friction coefficient between the sheet materials is generally about 50% of the friction coefficient between the feeding roller and the sheet material, the force Fp is almost 50% of the force F shown in FIG. The force over the inclined surface 6a of 6 is not generated and is stopped by the inclined member 6 and separated from the uppermost sheet material 2a.
[0041]
Even when the contact surface 6b of the inclined member 6 with the feeding roller 4 is worn by friction with the sheet material and becomes a wear contact surface 6b 'shown by a broken line in FIG. 9, the inclined member 6 is a compression spring. 5, the separation condition can be maintained without changing the predetermined inclination angle θ ₂ (FIG. 6) of the inclined surface 6a.
[0042]
Further, by reducing the contact surface 6b of the inclined member 6 with the feeding roller 4, the nip portion with the uppermost sheet material 2a is reduced from the conventional nip width D1 to the nip width C1, and the uppermost sheet material 2a is reduced. Since the feeding amount of the nip width that applies the feeding force to the next sheet material 2b is reduced by the rotation of the feeding roller 4 after the rear end portion of the sheet material 2a passes through the nip portion, the sheet material 2 is double fed. It becomes possible to suppress.
[0043]
FIG. 10 is an explanatory view showing the separating portion in an enlarged manner, and the sheet material 2 is kept horizontal. As described above, when the sheet feeding angle of the sheet material is horizontal, the lowest point of the feeding roller 4 is the point of action of the feeding pressure P, and when this point X is the origin, the feeding roller 4 and the inclined member. A contact point with the inclined surface 6 a of 6 is a nip forming portion N.
In such a configuration, r: radius of the feeding roller P: paper feeding pressure Q: separation pressure θ ₁ : angle (°) formed between the pressing direction of the separation pressure and the feeding direction of the sheet material
θ ₂ : Angle (°) formed by the inclined surface of the inclined member and the feeding direction of the sheet material
θ _p2 : Angle (°) formed between the tangent line of the nip forming portion of the feed roller and the inclined surface of the inclined member
N: Nip forming part μ ₁ : Friction coefficient between the feeding roller and the sheet material μ ₂ : Friction coefficient between the inclined surface of the inclined member and the sheet material tip _{p 12} : First and second sheets of the sheet material Friction coefficient between eyes Δμ _p : Difference in friction coefficient between sheets.
[0044]
Here, θ _p2 = θ ₁ + θ ₂ −90 ° (1)
When the point X is the origin, the coordinates (N _x , N _y ) of the nip forming portion N are as follows.
N _x = r · cos (−θ ₁ ) (2.1)
N _y = r + r · sin (−θ ₁ ) (2.2)
It becomes. As an example, if r = 16, θ ₁ = 76 °, and θ ₂ = 60 °, N (3.871, 0.475) is obtained.
[0045]
Next, an inequality is created from the relationship between the forces acting on the sheet material 2, and there are two areas: a region until the tip of the sheet material 2 reaches the nip forming portion N and a nip approach process held by the nip forming portion N. Description will be made with reference to FIGS. 11 and 12 (a) and 12 (b). Referring to FIG. 11, immediately before the nip, the vertical drag R _f acts on the front end of the sheet material 2 from the inclined surface 6 a of the inclined member 6. In order for the leading edge of the sheet material 2 to reach the nip forming portion N, bending deformation is required. At this time, the force acting on the leading edge of the sheet material differs depending on the type of the sheet material, and becomes large for thick paper.
[0046]
Now, it is assumed that the front end of the sheet material is in the same direction as the tangent to the outer periphery of the feeding roller in the nip forming portion N, and the front end of the sheet material does not contact other members at a place other than the sheet feeding pressure acting. Since the transport force of the uppermost sheet material 2a is (μ ₁ −μ _p12 ) · P and the double feed force of the double feed paper is Δμ _p · P, in order to prevent non-feed NF,
(Μ ₁ −μ _p12 ) · P> R _f · A
∴P> R _f · A / (μ ₁ −μ _p12 ) (3)
To prevent double feed MF,
Δμ _p · P <R _f · A
∴P <R _f · A / Δμ _p (4)
A = sin θ _p2 + μ ₂ · cos θ _p2 (5)
[0047]
Next, a process in which the leading edge of the sheet material enters the nip forming portion will be described with reference to FIGS. At this time, the front end of the sheet material receives the vertical drag Q _n and the frictional force μ ₂ · Q _n from the inclined surface of the inclined member. It is from the feed roller to reverse by the force caused by the sheet leading end is pinched subjected to frictional forces mu ₁ · F _n between normal force F _n to the conveying direction. Therefore, the separation pressure Q is
F _n + R _f · B = Q (6)
Q _n · B = Q (7)
B = cos θ _p2 −μ ₂ · sin θ _p2 (8)
In addition, as a condition for preventing the non-feed in the longitudinal direction of the sheet material, from the above formulas (6) and (7), (μ ₁ −μ _p12 ) · P + μ ₁ · F _n > Q _n · A
∴P> {(A / B) −μ ₁ } Q / (μ ₁ −μ _p12 )
+ Μ ₁ · R _f · B / (μ ₁ −μ _p12 ) (9)
[0048]
As a condition to prevent double feeding,
Δμ _p · P + μ _p12 · F _n <Q _n · A
Substituting the formulas (6) and (7) into this, P <{(A / B) −μ _p12 } Q / Δμ _p
+ Μ _p12 · R _f · B / Δμ _p (10)
Summarizing the coefficients of Equations (9) and (10) together,
P> C · Q + D (11) as a conditional expression for preventing non-feed
As a conditional expression for preventing double feed, P <G · Q + H (12)
C = {(A / B) −μ ₁ } / (μ ₁ −μ _p12 ) (13)
D = μ ₁ · R _f · B / (μ ₁ −μ _p12 ) (14)
G = {(A / B)-[ _mu ] _p12 } / [Delta] [mu] _p (15)
H = μ _p12 · R _f · B / Δμ _p (16)
[0049]
Next, when looking at the force acting on the sheet material tip, the sheet material tip is bent and deformed, so that force is received from the inclined surface of the inclined member, and the component force perpendicular to the inclined surface becomes the aforementioned normal force _Rf. . In order to obtain this value easily, it is preferable that a concentrated load W is applied to the tip of a beam of length L with one end fixed as shown in FIG. At this time, the deflection y _{max at} the tip of the beam is expressed by the following equation.
^{_{y 1max = W · L 3/}} 3 · E · I (17)
^{I = b · t 3/12} (18)
Where I: sectional moment of inertia E: Young's modulus b: beam width t: beam thickness.
[0050]
Therefore, the fixed point of the X point of action of the sheet feeding pressure P (the origin) is the beam in FIG. 10, when determining the normal force R _f assuming sheet leading end to the nip forming portion N of the sheet material is deformed,
W = 3 · E · I · N _y / L ³ = R _f · B
∴R _f = 3 · E · I · N _y / B · L ³ (19)
L = √ (N _x ² + N _y ² ) (20)
Table 1 below shows the value of the normal force _Rf calculated for thick paper A, thick paper B, thin paper A, and thin paper B having different thicknesses using the above equation (19). Note that the width b of the sheet material is 50 mm, which is the same as the width of the feeding roller, and the values of t and E are actually measured.
[0051]
[Table 1]

[0052]
Here, an actual value is substituted into each variable of the mathematical formula shown above, and the sheet material separation method according to the present application is compared with a sheet material separation method using a general conventional separation pad. In addition, as the value of the difference Δμ _{p in} the friction coefficient between the sheet materials, three levels were used in consideration of the use of the backing paper. Table 2 below shows an example of substitution values for each variable.
[0053]
[Table 2]

[0054]
FIG. 14 shows the above-described NF slope: (3), MF slope: (4) in the sheet material feeding method according to the present invention, with the vertical axis representing the paper feed pressure P and the horizontal axis representing the separation pressure Q. FIG. 4 is a diagram showing boundary lines obtained from NF nip: (11) formula and MF nip: (12) formula, respectively. Also shows three corresponding to [Delta] [mu _p of 3 levels with respect to MF border. Also it shows the MF boundary line corresponding to [Delta] [mu _p of three levels with regard FP separation method using the separation pad. Further, as a reference, the P. P. The Q setting area is also shown. The paper feed pressure and the separation pressure can be measured by means such as a spring balance or a pressure sensor. In the measurement, it is more preferable in consideration of the weight of the sheet material.
[0055]
As can be seen from FIG. 14, when the friction coefficient difference Δμ _p = 0.2 between the sheet materials assuming the addition of the backing paper, the double feed area of the FP separation method is considerably large, and general PQ setting is performed. Can not cope. On the other hand, in the sheet material separation method of the present application, there is a considerable margin to the double feed region even when Δμ _p = 0.2.
[0056]
The following equation (21) shows the MF boundary line in the FP separation method.
P <(μ _FP −μ _p12 ) Q / Δμ _p (21)
On the other hand, the slope of the MF boundary line in the sheet material separation method of the present application is {(A / B) −μ _p12 } / Δμ _p from the equation (15).
It is. From this, it can be seen that the value corresponding to the FP friction coefficient μ _FP in this separation method is A / B. This is a coefficient that determines the component force of the force acting on the front end of the sheet material. In the setting example of each variable shown in Table 2, A / B = 1.4 (22) from the expressions (5) and (8).
This is equivalent to an apparent μ _FP of 1.4. This is considered to be a factor that the sheet material separation method of the present application can obtain a much wider layer margin than the FP separation method. In this case, the ratio of the slope of the double feed boundary line between the present application and the FP separation method is as follows.
_{{(A / B) -μ p12} } / (μ FP -μ p12) ≒ 4.1 (23)
Thus, the double feed margin of the present application is about four times as large as that of the FP separation method.
[0057]
Further, in order to confirm the double feed margin in the case of rug paper (bond paper) or recycled paper in which the friction coefficient μ _p12 between the first and second sheets of the sheet material is large, μ _p12 = 0. FIG. 15 shows a PQ diagram when 77, Δμ _p = 0.2. From FIG. 15, it can be seen that if the sheet feeding pressure P is sufficiently obtained, it is possible to separate even the backing paper having a high coefficient of friction between the sheet materials by the sheet material separation method of the present application.
[0058]
Next, FIG. 16 shows the double feed MF region and the non-feed NF when the angle (θ ₂ ) between the inclined surface 6a of the inclined member 6 and the feeding direction of the sheet material 2 is swung from 50 ° to 70 °. FIG. 15 is a diagram similar to FIG. 14 showing the area based on experimental data, with the vertical axis representing the paper feed pressure P and the horizontal axis representing the separation pressure Q. As is apparent from FIG. 16, it is possible to cope with the difference Δμ _p = 0.2 in the friction coefficient between the sheet materials in the setting region indicated by the solid square line. However, when the angle θ ₂ is set to 70 °, the non-feed NF region becomes severe. However, the separation pressure / sheet feeding pressure such as the setting region θ ₂ = 70 ° indicated by the dashed line in FIG. If it corresponds, it can be set sufficiently.
[0059]
FIG. 17 is a diagram in which the thick paper A non-feed (NF) area obtained from the above-described conditional expression is compared with the actual measurement value. In the thick paper A non-feed NF area, μ ₁ = 1.3, μ It is confirmed by actual measurement that the approximation is made at _p = 0.67, and in the thin paper B double feed MF region, the approximation is made at μ ₂ ′ = 0.15, μ _p = 0.54, Δμ _p = 0.048. . The other substitution values and the values of the vertical drag _Rf from the inclined surfaces of the thick paper A and the thin paper B are the same as those in the above-described Tables 1 and 2. As described above, it was found that by inputting the friction coefficient data separately measured in each conditional expression, it was found to approximate the measured value, and the effectiveness of each conditional expression was proved.
[0060]
In the sheet material feeding apparatus having such a configuration, since the inclined member 6 has a complicated shape, it is preferable to integrally mold the synthetic resin with a synthetic resin. In this case, as shown in FIGS. 18 and 19, if the length A of the contact surface 6 b of the inclined member 6 is larger than the length B in the axial direction of the feeding roller 4, the sheet material (not shown) is fed. The contact surface 6b of the inclined member 6 that is pressed in the direction of the roller 4 and is in sliding contact with the sheet material is pressed against the feeding roller 4 through the sheet material because the separation pressure is applied to the center portion thereof. Only the central portion of the contact surface 6b is worn and depressed.
[0061]
When the inclined member 6 is deformed in this way, when the sheet material enters between the feeding roller 4 and the inclined member 6, the sheet material is fed while being curved along the deformed contact surface 6b of the inclined member 6. Is done. Therefore, the conveyance load of the sheet material becomes remarkably large, or the sheet material having strong rigidity cannot be bent, and non-feed occurs. Therefore, as shown in FIG. 5, the length of the abutting surface 6b of the inclined member 6 is made smaller than the length of the feeding roller 4 in the axial direction so that the entire length of the abutting surface 6b contacts the feeding roller 4 at all times. It is possible to contact.
[0062]
According to such a configuration, since the contact surface 6b of the inclined member 6 is pressed by the feeding roller 4 through the sheet material over the entire length, a partially depressed portion is formed on the contact surface 6b. As a result, the contact surface 6b wears out on average in a straight line. Since the inclined member 6 moves in the direction of the feeding roller 4, even if the contact surface 6b is worn, the inclined surface 6a of the inclined member 6 makes a predetermined angle with respect to the sheet material conveying direction S. It is possible to keep.
[0063]
From the results of repeated experiments, in this embodiment, the conditions for good separation of the sheet material 2 are as follows. As shown in FIG. 20, the pressure contact portion of the sheet material 2 on the bottom plate 1 pressed against the feeding roller 4 The distance K in the sheet material feeding direction between X and the pressure contact portion N of the inclined member 6 pressed against the feeding roller 4 is set to 2 to 6 mm, and the inclined surface of the inclined member 6 with respect to the feeding direction S of the fed sheet material 2 the angle theta ₂ of 6a was found that better to 50 ° to 70 °.
[0064]
In this way, as long as the feeding roller 4 is in a size that is normally used, for example, in the range of φ16 to 36 mm, a plurality of sheet materials 2 fed from the bottom plate 1 by the feeding roller 4 on the inclined surface 6a. Pre-separation, that is, separation by shifting between the sheet material 2a and the sheet material 2b opened from the sheet material 2a, and the separation is performed at the contact surface 6b, so that a good separation quality is always obtained. It was confirmed.
[0065]
As described above, the relationship between the sheet material 2 stacked on the bottom plate 1, the feeding roller 4, and the inclined member 6 has been modeled and described in detail with reference to FIGS. For the purpose of modeling, the inclined member 6 has been described as having only the convex portion 61. However, when only the convex portion 61 is provided, even when various conditions such as the angle θ ₂ are set as described above, the sheet material in which burrs are generated in the cutting process in the sheet material manufacturing process is fed. When the friction coefficient μ between the sheet materials and the like is higher than expected, there is a possibility that the margin for the multiple sheet materials 2 getting over the inclined surface 6a and causing the sheet materials to be double fed may be reduced. As shown in FIG. 22, the occurrence of double feeding of the sheet material 2 cannot be denied.
[0066]
Therefore, in order to further improve the separation performance, the inclined member 6 according to the present invention is different from the inclined member 6 when modeled, that is, the inclined member 6 having only the convex portion 61, a plurality of convex portions 61, 61 ′, 61. Accordingly, as shown in FIG. 21, even when the plurality of sheet materials 2 get over the convex portion 61, the convex portion 61 located on the downstream side in the direction S from the convex portion 61. By ', 61', only the uppermost sheet material 2a is separated and double feeding is prevented, and only one sheet material 2a is sent to the image forming unit 34 by the conveying roller pair 7.
[0067]
Here, since each of the convex portions 61, 61 ′, 61 ″ has various conditions such as the angle θ ₂ as described above, each has good separation performance such as good pre-separation performance. In addition, the length of the contact surface 6b of the convex portion 61 is made smaller than the length of the feed roller 4 in the axial direction so that the entire length of the contact surface 6b can always contact the feed roller 4. As described above, the same applies to the contact surface 6b ′ of the convex portion 61 ′ and the contact surface 6b ″ of the convex portion 61 ″.
[0068]
Since the image forming apparatus 30 is configured as described above, a writing device 33 is provided in the image forming unit 34 based on image data read by the optical reading system 32 provided in the image forming apparatus main body 31. A latent image is formed on the photosensitive drum 35 charged by the charging device 56, and the developing device 36 provided in the image forming unit 34 converts the latent image into a visible image with toner.
[0069]
The sheet material 2 stacked on the bottom plate 1 from the cassette 11 of the feeding device 100 is fed by the feeding roller 4, and the sheet material 2 is well separated one by one by cooperation with the inclined member 6. Only the sheet material 2 is conveyed to the image forming unit 34 through the conveyance path 37 by the conveyance roller pair 7, and the visible image on the photosensitive drum 35 is transferred onto the sheet material 2 by the transfer device 59. After the transfer, the photosensitive drum 35 is cleaned by the cleaning device 50 and is again charged by the charging device 56.
[0070]
The sheet material 2 to which the toner image has been transferred is conveyed to the fixing device 38 where fixing is performed. When the sheet material 2 is conveyed to the sheet discharge roller pair 39 via the sheet discharge branch claw 51, the sheet discharge roller pair 39 causes the external sheet discharge tray to move. 40 is discharged. At the time of double-sided image formation, the sheet material 2 is conveyed from the reverse conveyance path 41 to the double-sided device 42 by the paper discharge branch claw 51, temporarily stored in the double-sided tray 43, reverses the traveling direction, and again from the double-side conveyance path 44 The image is sent to the image forming unit 34 to form an image on the back surface, and is discharged onto the paper discharge tray 40 through the fixing device 38, the paper discharge branch claw 51, and the paper discharge roller pair 39.
[0071]
Although the present embodiment has been described above, the embodiment is not limited to the above-described embodiment, and can take other modes within the scope to which the present invention can be applied. For example, in FIG. 1, only one feeding device 100 is shown to simplify the drawing, but a plurality of paper feeding devices having different sizes may be provided as necessary. In this case, the present invention can be applied to any sheet material feeding apparatus, and a separation member to which the present invention is applied can be used. The feeding means may be a belt-like paper feeding belt instead of the paper feeding roller.
[0072]
A plurality of contact portions may be provided in the direction S, and is not limited to three. The inclined portion may be formed at least on the most upstream convex portion in the direction S among the plurality of convex portions. This is because the leading edge of the sheet material first comes into contact with the most upstream inclined portion, so that pre-separation performance is most required. The uppermost inclined portion is not limited to be provided at the center in the width direction of the sheet material, but is preferably provided symmetrically with respect to the center in the width direction from the viewpoint of preventing skew of the sheet material, as in the present embodiment. If it is provided in the portion, only one uppermost convex portion is required, which is preferable in that the number of the entire convex portion can be suppressed.
[0073]
In the present embodiment, the downstream contact surface is provided at a different position in the width direction of the sheet material so as not to overlap the upstream contact surface, but partially overlaps with the upstream contact surface. Alternatively, they may be provided at different positions. Between the upstream abutment surface and the feeding means, the plurality of sheet materials overcoming the convex portion are tightly sandwiched, but shifted from the upstream abutment surface in the width direction of the sheet material. In the position, the sheet material tends to occupy a position separated from the feeding means and other sheet materials by its own weight, and therefore, the downstream convex portion provided at a position different from the upstream contact surface is This is because the separation performance is improved.
[0074]
【The invention's effect】
The present invention is arranged opposite to a feeding unit that feeds a sheet material from the sheet material stacking member, and separates the sheet material fed from the sheet material stacking member by the feeding unit one by one with the feeding unit. And a plurality of the contact surfaces in the sheet material feeding direction, so that the plurality of sheet materials get over the contact surface upstream in the sheet material feeding direction. Since the sheet material is separated by the contact surface on the downstream side, the separation performance of the sheet material is improved even when the friction coefficient is extremely large due to the large burr of the sheet material, etc. It is possible to provide a separation member that can reliably prevent double feeding of sheet materials and contribute to feeding only one sheet material.
[0075]
A slanted surface inclined with respect to the sheet material feeding direction with which the leading edge of the sheet material fed from the sheet material stacking member engages, and this slanted surface is at least the most of the contact surfaces in the feeding direction. If the upstream contact surface is arranged upstream in the feed direction, the pre-separation is performed by the inclined surface, so that a plurality of sheet materials are contacted upstream in the sheet feed direction. The sheet material is separated by the contact surface on the downstream side even if it gets over the scale, so even if the friction coefficient is extremely large due to the large burr of the sheet material, etc. Therefore, it is possible to provide a separating member that can more reliably prevent double feeding of sheet materials and contribute to feeding only one sheet material.
[0076]
If the contact surface on the most upstream side in the sheet material feeding direction among the contact surfaces is disposed at the center in the width direction of the sheet material, a relatively simple shape with a reduced number of contact surfaces Thus, it is possible to provide a separation member that can contribute to prevention of sheet material double feeding while preventing skew of the sheet material.
[0077]
Of the contact surfaces, the contact surface on the downstream side in the sheet material feeding direction is arranged at a position different from the position in the width direction of the sheet material on the contact surface upstream of the contact surface. Since the contact surface on the downstream side in the sheet material feeding direction occupies a position suitable for separation, even if a plurality of sheet materials get over the contact surface on the upstream side in the sheet material feeding direction, the downstream contact surface Since the separation performance by the sheet material is improved, only one sheet material can be reliably separated by the downstream contact surface, and even when the friction coefficient is extremely large due to the large burr of the sheet material, etc. Since the separation performance of the sheet material is further improved, it is possible to provide a separation member that can more reliably prevent double feeding of the sheet material and contribute to feeding only one sheet material.
[0078]
The present invention provides a sheet material stacking member for stacking a sheet material, a feeding unit that engages with and feeds the sheet material stacked on the sheet material stacking member, and the sheet material stacking member by the feeding unit. A sheet material feeding device having the separation member according to any one of claims 1 to 3 for separating the sheet material fed from the sheet one by one, and the separation having the above-described effects Even if a plurality of sheet materials cross the upstream contact surface in the sheet feeding direction, only one sheet material is separated by the downstream contact surface, so the sheet material has a large burr. Even when the coefficient of friction is extremely large due to, for example, the separation performance of the sheet material has been improved, so that the sheet material can be reliably prevented from being fed and only one sheet material can be fed Providing a material feeding device It can be.
[0079]
The invention according to claim 6 is the image forming apparatus having the separating member according to any one of claims 1 to 4 or the sheet material feeding device according to claim 5. The separation member or the sheet material feeding device has the function of separating the sheet material from the downstream contact surface even if the multiple sheet materials get over the upstream contact surface in the sheet material feed direction. Therefore, even when the friction coefficient is extremely large due to the large burrs of the sheet material, etc., the separation performance of the sheet material is improved. It is possible to provide an image forming apparatus that can feed only one sheet and that can satisfactorily form an image even on a sheet material having a very large friction coefficient due to a large burr or the like.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view illustrating a schematic configuration of a separation member to which the present invention is applied, a sheet material feeding device having the separation member, and an image forming apparatus having the separation member.
FIG. 2 is a longitudinal sectional view of a main part of the sheet material feeding apparatus shown in FIG.
FIG. 3 is an exploded perspective view of the sheet material feeding device shown in FIG. 1;
4 is an enlarged perspective view of the separating member shown in FIG. 1. FIG.
5 is a perspective view of the separation member shown in FIG. 1 and an exploded perspective view of a main part of the sheet material feeding device shown in FIG. 1;
6 is an explanatory diagram showing an enlarged part of a model of the sheet material feeding device shown in FIG. 2;
7 is an explanatory diagram illustrating a force relationship of the uppermost sheet material in the sheet material feeding device illustrated in FIG. 6;
FIG. 8 is an explanatory diagram showing a force relationship of a sheet material under the uppermost sheet material in the sheet material feeding device shown in FIG. 6;
FIG. 9 is an explanatory diagram showing a worn state of an inclined member in the sheet material feeding apparatus shown in FIG. 6;
FIG. 10 is an explanatory diagram showing an enlargement of a separation unit in the sheet material feeding device shown in FIG. 6;
11 is an explanatory diagram showing a relationship of forces acting on the front end of the sheet material immediately before the nip in the sheet material feeding apparatus shown in FIG. 6;
12 is an explanatory diagram showing a force relationship acting on the front end of the sheet material when entering the nip in the sheet material feeding device shown in FIG. 6; FIG.
FIG. 13 is an explanatory view showing a bending state of a beam due to a concentrated tip load.
14 is a diagram showing an example of a sheet material separating method by the sheet material feeding device shown in FIG. 6 in comparison with a sheet material friction separating method by a conventional sheet material feeding device.
15 shows another example of the line of the sheet material separating method by the sheet material feeding device shown in FIG. 6 in comparison with the sheet material friction separating method by the conventional sheet material feeding device. FIG.
16 is a diagram illustrating a setting region when the angle when the leading edge of the sheet material feeding direction abuts the inclined surface from 50 ° to 70 ° in the sheet material feeding device illustrated in FIG. 6; is there.
FIG. 17 is a diagram comparing non-feed areas and multi-feed areas of sheet materials having different thicknesses in the same state as in FIG. 16 using actual measurement and conditional expressions.
FIG. 18 is an exploded perspective view of a comparative example showing the relationship between the lengths of the feeding roller and the inclined member in the axial direction of the feeding roller.
FIG. 19 is a cross-sectional view of a comparative example of a feeding roller and an inclined member, showing a relationship in length between the feeding roller and the inclined member in the axial direction of the feeding roller.
20 is an explanatory diagram showing a relationship between a feeding roller and an inclined member in the sheet material feeding device shown in FIG. 6;
FIG. 21 is a schematic diagram showing a state in which only one uppermost sheet material is separated and fed by a separation member to which the present invention is applied.
FIG. 22 is a schematic view showing a state in which a plurality of sheet materials have overcome a conventional separating member.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Sheet material stacking member 2 Sheet material 4 Feeding means 6 Separation member 6a, 6a ', 6a "Inclined surface 6b, 6b', 6b" Contact surface 6b Uppermost contact surface 6b Upstream contact surface 6b ', 6b "Contact surface 30 on the downstream side Image forming apparatus S Sheet material feeding direction

Claims (6)

The sheet material is disposed opposite to the sheet feeding unit that feeds the sheet material from the sheet material stacking member. The sheet feeding unit separates the sheet material fed from the sheet material stacking member one by one from the sheet feeding unit. A separating member having a contact surface,
A separation member comprising a plurality of the contact surfaces in the sheet material feeding direction. The separation member according to claim 1, further comprising an inclined surface inclined with respect to a sheet material feeding direction with which a leading edge of the sheet material fed from the sheet material stacking member is engaged, A separating member, wherein the separating member is disposed on the upstream side in the feed direction of at least the most upstream contact surface in the feed direction. The separation member according to claim 1 or 2, wherein the contact surface on the most upstream side in the feeding direction among the contact surfaces is disposed at a central portion in the width direction of the sheet material. The separation member according to any one of claims 1 to 3, wherein, among the contact surfaces, a downstream contact surface in the feeding direction is defined as a sheet material of a contact surface upstream from the contact surface. A separating member, wherein the separating member is disposed at a position different from the position in the width direction. A sheet material stacking member for stacking the sheet material, a feeding unit that engages with the sheet material stacked on the sheet material stacking member and feeds the sheet material, and is fed from the sheet material stacking member by the feeding unit The sheet | seat material feeding apparatus which has a separating member as described in any one of Claim 1 thru | or 4 for isolate | separating a sheet | seat material sheet by sheet. An image forming apparatus comprising the separation member according to claim 1 or the sheet material feeding device according to claim 5.

Images