JP2004196538A

JP2004196538A - Paper feeding device

Info

Publication number: JP2004196538A
Application number: JP2002370585A
Authority: JP
Inventors: Toshihiko Seike; 俊彦清家; Hidetoshi Kaneko; 英敏金子; Shinji Oishi; 真嗣大石; Hideki Goto; 英樹後藤; Koichi Moriyama; 弘一森山
Original assignee: Sharp Corp
Current assignee: Sharp Corp
Priority date: 2002-12-20
Filing date: 2002-12-20
Publication date: 2004-07-15
Anticipated expiration: 2022-12-20
Also published as: JP4119741B2

Abstract

<P>PROBLEM TO BE SOLVED: To uniformly increase paper conveying force regardless of the thickness of paper by providing a conveyance auxiliary member for suppressing a required space for arrangement by abutting on the outer peripheral surface of a paper feed roller downstream of the arranged position of a paper separating member in a paper conveying direction. <P>SOLUTION: One end of the conveyance auxiliary member 28 formed of a thin plate member is allowed to abut on the outer peripheral part of the paper feed roller 26 downstream of the arranged position of the paper separating member 27 in the paper conveying direction. The abutting face is formed in circular arc shape, and the other end is fixed to a guide 29. Abutting force is thereby applied to the outer peripheral part of the paper feed roller 26 from the conveyance auxiliary member 28 in a downstream direction from the upstream side in the paper conveying direction. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

【０００１】
【発明の属する技術分野】
この発明は、複写機、ファクシミリ装置等の画像形成装置や原稿の画像面の画像を読み取る画像読取送等の装置において、収納又は載置されている用紙又は原稿の搬送を行う給紙装置に関する。
【０００２】
【従来の技術】
従来、画像読取装置や画像形成装置等では、ホッパや給紙トレイ等に収納又は載置された複数枚の原稿や用紙等を、ピックアップローラや給紙ローラ等を回転駆動して１枚ずつ取り出し、用紙搬送路上に配置された原稿読取部や画像形成部に搬送する。
【０００３】
上述の構成では、収納等された複数枚の用紙等が用紙間の摩擦作用によって１枚ずつ取り出されずに数枚に重なって取り出されてしまう場合があった。そこで、従来の給紙装置には、給紙ローラの外周部に圧接し、給紙ローラとは逆に回転駆動されるセパレータローラを配置し、その給紙ローラの外周部とセパレータローラとの圧接部に用紙を搬送し、上記圧接部で用紙を１枚ずつ捌いて搬送するものがあった（例えば、特許文献１参照。）。
【０００４】
また、図４に示すように、給紙ローラ１５１の外周部に圧接するように弾性部材等から構成される用紙捌き部材１５２を配置し、給紙ローラ１５１の外周部と用紙捌き部材１５２との圧接部に用紙を搬送し、上記圧接部で用紙を１枚ずつ捌いて用紙搬送路Ｓに搬送するものがあった。
【０００５】
しかし、上述の特許文献１の構成では、用紙が薄紙又は普通紙（５０〜１００ｇ／ｍ² ）と厚紙（１２８ｇ／ｍ² 以上）では用紙の厚みが異なるため、回転軸が給紙ローラに対して固定されたセパレータローラでの負荷が異なり、給紙ローラの搬送力が異なってしまう。つまり、用紙の種類によってその厚みが異なるので、給紙ローラとセパレータローラとの圧接部を通過する際、厚い用紙ほど上記圧接部で圧接されて摩擦が大きくなるので薄い用紙よりも搬送力が大きくなる。また、セパレータローラは、給紙ローラに従動せずに逆に回転するため、用紙の搬送力を抑える方向に作用してしまう。上述の給紙ローラ１５１と用紙捌き部材１５２との構成についても同様である。
【０００６】
そのため、近年の給紙装置では、図５に示すように用紙搬送方向における用紙捌き部材１５２の配置位置の下流側に給紙ローラ１５１に当接する補助ローラ１５５を配置したものがある。補助ローラ１５５は、弾性部材１５６を有し、給紙ローラ１５１の外周部に対して、給紙ローラ１５１との当接部の法線方向に弾性部材１５６からの弾性力を当接力として付与する。また、補助ローラ１５５の回転軸は、上記法線方向に移動自在である。これによって、給紙ローラ１５１と補助ローラ１５５との当接部に用紙が通過する際に、用紙が給紙ローラ１５１に当接するので、薄い用紙においても搬送力が増加し、十分な搬送力が保持される。
【０００７】
また、側面視略Ｕ字型の給送経路上において、ガイド部材のガイド面にガイドローラを設け、用紙搬送路上を搬送される用紙の後端部がガイド部材との接触によって、用紙の搬送に抗する力（バックテンションとも言う。）を軽減し、さらに給紙ローラから搬送ローラへ向かう用紙の進行角度を規制し、用紙と搬送ローラとの接触面積を高めると同時に用紙から受ける反力を搬送従動ローラの押圧力に変換することで、搬送ローラによる用紙の搬送を確実にするものがある（例えば、特許文献２参照。）。
【０００８】
【特許文献１】
特開平２−１３５３０号公報
【特許文献２】
特開２００１−２３３４９７公報
【発明が解決しようとする課題】
しかしながら、図５に示すような補助ローラ１５５を配置した構成では、用紙が当接部を通過する際に、用紙の厚みにより補助ローラ１５５が上記法線方向の弾性部材１５６側に押動されるが、その押動される方向と弾性部材１５６が弾性力を付与する方向とが対向するため、補助ローラ１５５が用紙の厚みによって押動されることが困難で、逆に用紙の厚みに対する弾性部材１５６からの反力が当接力に加わる。したがって、用紙を搬送するのに必要な搬送力を増加させることはできるが、厚い用紙が上記当接部を通過する場合は、薄い用紙よりも大きな当接力を付与されて搬送力が大きくなってしまい、用紙の厚みに係わらず一定の搬送力を付与することが困難である。そのため、用紙を送るタイミングが用紙の厚みで異なり、斜め搬送や画像形成等の次工程に用紙を搬送するタイミングのずれが生じる可能性がある。また、搬送力を増加させるために、上記当接部におけるニップ幅である用紙が給紙ローラ１５１の外周部に当接する面積を大きくするための補助ローラ１５５を配置する大きなスペースを確保しなければならない。
【０００９】
一方、上述の特許文献２の構成では、側面視略Ｕ字型の給送経路上にガイドローラを設けて用紙のバックテンションを軽減し、給紙ローラから搬送ローラへ搬送する際の進入角度を規制して搬送ローラによって用紙の搬送力を高めるが、給紙ローラによって用紙の搬送力を高める構成ではないので、図５に示すような下方から上方へ伸びるような用紙搬送路Ｓの構成では、十分な搬送力が得られない可能性がある。
【００１０】
この発明の目的は、用紙搬送方向の用紙捌き部材の配置位置における下流側で給紙ローラの外周部に当接し、配置に必要なスペースを抑えた搬送補助部材を設け、用紙の厚みに係わらず用紙の搬送力を一定に増加させることができる給紙装置を提供することにある。
【００１１】
【課題を解決するための手段】
この発明は、上記の課題を解決するために以下の構成を備えている。
【００１２】
（１）用紙搬送路上で回転駆動される給紙ローラの外周部に圧接する用紙捌き部材を配置した給紙装置において、
用紙搬送方向の前記用紙捌き部材の配置位置の下流側で前記給紙ローラの外周部に当接し、前記給紙ローラの外周部に対して用紙搬送方向における上流側から下流側に向かう方向に当接力を付与し、給紙ローラとの当接部の法線方向に移動自在な搬送補助部材を備えたことを特徴とする。
【００１３】
この構成においては、給紙ローラの外周部に圧接する用紙捌き部材が用紙搬送路上に配置された給紙装置において、用紙搬送方向の用紙捌き部材の配置位置の下流側で給紙ローラの外周部が当接される搬送補助部材によって、給紙ローラの外周部に対して用紙搬送方向における上流側から下流側に向かう方向に当接力が付与される。したがって、搬送補助部材によって給紙ローラの外周部が当接される際の当接力が、用紙搬送方向における上流側から下流側に向かう方向に付与されるので、用紙が給紙ローラと搬送補助部材との当接部を通過する際、上記当接力が影響せずに、用紙の厚みによって上記当接部の法線方向の給紙ローラ側とは反対方向に搬送補助部材が押動される。そのため、用紙の厚みに対する搬送補助部材からの反力が付与されず、用紙の厚みによって用紙に一定の当接力が付与される。
【００１４】
（２）前記搬送補助部材は、弾性変形する薄板部材で構成され、一端の前記給紙ローラとの当接部の接触面が円弧形状を呈し、他端が用紙搬送方向に対して固定されていることを特徴とする。
【００１５】
この構成においては、弾性変形する薄板部材で構成された前記搬送補助部材の一端が、前記給紙ローラに当接するように且つその接触面が円弧形状に形成され、また他端が用紙搬送方向に対して固定されている。したがって、搬送補助部材が薄板部材で且つ搬送補助部材の一端の上記当接部の接触面が円弧形状で形成されているので、搬送補助部材を配置するのに必要なスペースが大きくならず、且つ上記当接部のニップ領域が狭くなることがない。
【００１６】
（３）前記搬送補助部材の他端は、用紙搬送方向の用紙捌き部材の配置位置における上流側の用紙搬送路と前記当接部の接線方向との間に挟まれた範囲内に固定されることを特徴とする。
【００１７】
この構成においては、前記搬送補助部材の他端が、用紙搬送方向の用紙捌き部材の配置位置における上流側の用紙搬送路と前記当接部の接線方向との間に挟まれた範囲内に固定されるので、上記給紙ローラの外周部に対する当接力が、上記当接部における法線方向ではなく、用紙搬送方向における上流側から下流側に向かう方向に付与される。したがって、用紙が給紙ローラと前記搬送補助部材の一端との当接部を通過する際、上記当接力が影響せずに、用紙の厚みによって上記当接部の法線方向の給紙ローラ側とは反対方向に前記搬送補助部材の一端が押動されるように搬送補助部材全体が弾性変形する。そのため、用紙の厚みに対する搬送補助部材からの反力が付与されず、用紙の厚みによって用紙に一定の当接力が付与される。
【００１８】
【発明の実施の形態】
図１は、この発明の実施形態に係る給紙装置を適用した画像形成装置の構成を示す図である。この発明の本体装置である画像形成装置１００は、用紙（ＯＨＰ等の記録媒体を含む。）に画像を形成する画像形成モードとしてコピアモード、プリンタモード、ＦＡＸモードを有し、各モードはユーザによって選択される。
【００１９】
また、画像形成装置１００は、原稿読取部１０、給紙部２０、画像形成部３０、排紙部４０及び図示しない操作パネル部等から構成される。原稿読取部１０は、装置本体の上部に配置され、プラテンガラス１１及びスキャナ光学系１２等から構成される。スキャナ光学系１２は、光源１３、複数の反射ミラー１４ａ〜１４ｃ、光学レンズ１５及びＣＣＤ（Charge Coupled Device)１６を有する。光源１３は、プラテンガラス１１に載置された原稿に光を照射する。複数の反射ミラー１４ａ〜１４ｃは、原稿からの反射光を反射させて光学レンズ１５に導く。光学レンズ１５は、反射ミラー１４ａ〜１４ｃによって導かれた反射光を集光してＣＣＤ１６に導く。ＣＣＤ１６は、集光された反射光を光電変換する。
【００２０】
給紙部２０は、装置本体の下部に配置され、給紙トレイ２１、手差トレイ２２、ピックアップローラ２３及び給紙装置２５等から構成される。給紙トレイ２１及び手差トレイ２２は、画像形成時に用紙搬送路Ｓに給紙される用紙を載置する。ピックアップローラ２３は、各トレイ２１、２２に載置された用紙を用紙搬送路Ｓに給紙する。給紙装置２５は後述する。画像形成部３０は、原稿読取部１０の下方の手差トレイ２２側に配置され、図示しないレーザスキャニングユニット（以下、ＬＳＵと言う。）、感光体ドラム３１及び定着装置３６を有し、感光体ドラム３１の周囲に、帯電器３２、現像装置３３、転写装置３４及び除電器３５が感光体ドラム３１の回転方向である図１に示す矢印の方向に沿ってこの順に配置されている。
【００２１】
排紙部４０は、給紙トレイ２１の上方に配置され、排紙ローラ４１及び排紙トレイ４２等から構成される。排紙ローラ４１は、画像形成の終了した用紙搬送路Ｓ上の用紙を排紙トレイ４２に排出する。排紙トレイ４２は、排紙ローラ４１から排出される用紙を載置する。操作パネル部は、印字枚数や印字倍率等の各種設定の入力を受け付ける図示しない複数の入力キーを備えている。
【００２２】
コピアモードにおいて原稿の画像を用紙にコピーする際、原稿読取部１０のプラテンガラス１１にコピーしたい原稿を載置した後、操作パネル部に設けられた各入力キーを押下して印字枚数、印字倍率等の設定入力を行い、図示しないスタートキーを押下してコピー動作を開始する。
【００２３】
スタートキーが押されると、画像形成装置１００は、ピックアップローラ２３が回転して用紙搬送路Ｓに用紙が給紙される。給紙された用紙は、用紙搬送路Ｓ上に設けられたレジストローラ５１に搬送される。
【００２４】
レジストローラ５１に搬送された用紙の搬送方向の先端部は、用紙に転写されるべき感光体ドラム３１上に形成されるトナー画像との位置合わせを行うため、用紙の副走査方向とレジストローラ５１の軸方向とが平行になるようにレジストローラ５１に挟持される。
【００２５】
原稿読取部１０によって読み取られた画像データは、入力キー等を用いて入力された条件で画像処理が施された後、ＬＳＵにプリントデータとして送信される。ＬＳＵは、帯電器３２によって所定の電位に帯電された感光体ドラム３１表面に、図示しないポリゴンミラー及び各種レンズを介して上記画像データに基づいたレーザ光を照射して静電潜像を形成する。その後、現像装置３３の図示しない現像槽中に設けられた一部が感光体ドラム３１に対向するＭＧローラ３３ａ表面に付着しているトナーが、感光体ドラム３１表面上の電位ギャップに応じて感光体ドラム３１表面に引き寄せられて付着し、静電潜像が顕像化される。感光体ドラム３１上に残留したトナーは、図示しないドラムユニットのクリーニングブレードによって掻き取られ、図示しないクリーナユニットによって回収される。
【００２６】
その後、レジストローラ５１によって、レジストローラ５１に挟持されている用紙と、感光体ドラム３１表面に形成されたトナー画像との位置が合わせられ、用紙を感光体ドラム３１と転写装置３４との間に搬送する。次に、転写装置３４に設けられた転写ローラ３４ａを用いて感光体ドラム３１表面のトナー画像を上記用紙に転写する。トナー画像の転写が終了した用紙は、定着装置３６の上ヒートローラ３６ａと下ヒートローラ３６ｂとの間を通過することで熱と圧力が加えられるとともにトナー画像が溶融・固着され、用紙搬送路Ｓを搬送されて排紙ローラ４１によって排紙トレイ４２に排出される。
【００２７】
図２は、この発明の実施形態に係る給紙装置を適用した画像形成装置の一部の構成を拡大した断面図である。図２に示すように、ピックアップローラ２３によって用紙搬送路Ｓに取り出された用紙を、用紙搬送路Ｓ上に配置されている画像形成部３０等に搬送するための給紙装置２５は、用紙搬送路Ｓ上に配置された給紙ローラ２６、用紙捌き部材２７及び搬送補助部材２８等から構成される。給紙ローラ２６は、反時計回りに回転駆動され、用紙搬送方向である矢印Ｘ方向に用紙を搬送する。用紙捌き部材２７は、弾性部材２７ａを有し、給紙ローラ２６の外周部に圧接する。また、用紙捌き部材２７は、給紙ローラとの圧接部に複数枚重なった用紙が搬送された場合に用紙を１枚ずつ搬送するように捌く。
【００２８】
搬送補助部材２８は、弾性変形する薄板部材で構成され、一端が給紙ローラ２６に弾性変形による弾性力により当接し、他端が用紙を矢印Ｘ方向に規制するガイド２９に固定されている。また、搬送補助部材２８は、給紙ローラ２６との当接部に対して、当接部の法線方向よりも矢印Ｘ方向に傾斜した矢印Ｙ方向に当接力を付与し、用紙の搬送力を増加させる補助を行う。つまり、用紙が上記当接部を通過する場合、回転駆動によって用紙に搬送力を付与する給紙ローラ２６に用紙を当接させて用紙と給紙ローラ２６との摩擦を増加させることで搬送力を増加させる。
【００２９】
上記の場合、用紙の厚みによって搬送補助部材２８の一端の当接部の当接面に法線方向の給紙ローラ２６側とは反対方向である矢印Ｚ方向の力が加わり、搬送補助部材２８は、一端が矢印Ｚ方向に押動されるように弾性変形する。ここで、上記当接力が矢印Ｚ方向とは反対方向に作用することがないので、厚みが異なる用紙を搬送しても厚みによって容易に搬送補助部材２８が弾性変形する。したがって、用紙の厚みに対する搬送補助部材２８からの反力が当接力に加わらず、用紙の厚みに係わらず用紙に当接力を一定に付与できるので、用紙の厚みに係わらず搬送力を一定に増加させることができる。
【００３０】
なお、搬送補助部材２８の一端は、給紙ローラ２６との当接部の当接面が円弧形状で形成されている。これによって、上記当接面が平面形状の場合よりも上記当接部のニップ領域が増加し、用紙を当接する面積を増加させることができるので、給紙ローラ２６と用紙との摩擦が増え、搬送力を効率的に増加させることができる。
【００３１】
以上のようにして、この発明の実施形態に係る給紙装置２５では、円弧形状を呈する一端を矢印Ｘ方向の用紙捌き部材２７の配置位置の下流側で給紙ローラの外周部に当接し、他端をガイド２９に固定した搬送補助部材２８が、給紙ローラ２６の外周部に対して矢印Ｙ方向に当接力を付与することによって、用紙が上記当接部を通過する際に、用紙の厚みに係わらず搬送力を一定に増加させることができる。
【００３２】
また、搬送補助部材２８を薄板部材で且つ搬送補助部材２８の一端における上記当接部の接触面を円弧形状に形成することによって、搬送補助部材２８を配置するのに必要なスペースを抑えつつ上記当接部のニップ幅を増加させることができ、搬送力を増加させることができる。
【００３３】
なお、この発明の搬送補助部材２８の他端の固定位置は、ガイド２９に固定されているが、特にこれに限定されることはない。矢印Ｘ方向の用紙捌き部材２７の配置位置における上流側の用紙搬送路Ｓと上記当接部の接線方向との間に挟まれた図３に示す斜線部分の範囲内であれば、当接力を付与する方向が矢印Ｚ方向と反対方向にならず、給紙ローラ２６の外周部に対して矢印Ｘ方向における上流側から下流側に向かう方向に当接力を付与できるので、上述と同様の効果を得ることができる。
【００３４】
また、この発明は、画像形成装置に設けられた給紙装置に限らず、ファクシミリ装置、画像読取装置等の用紙又は原稿の搬送を行う装置にも適用可能である。
【００３５】
【発明の効果】
この発明によれば、以下の効果を奏することができる。
【００３６】
（１）搬送補助部材を用紙搬送方向の用紙捌き部材の配置位置の下流側で給紙ローラの外周部に当接し、給紙ローラの外周部に対して用紙搬送方向における上流側から下流側に向かう方向に当接力を付与することによって、用紙の厚みに応じて搬送補助部材が容易に押動されるので、用紙に当接力を一定に付与することができ、用紙の厚みに係わらず用紙の搬送力を一定に増加させることができる。
【００３７】
（２）弾性変形する薄板部材で構成し前記搬送補助部材の一端を、前記給紙ローラに当接するように且つその接触面を円弧形状に形成することによって、搬送補助部材を配置するのに必要なスペースを抑えつつ上記当接部のニップ幅を増加させることができ、搬送力を増加させることができる。
【００３８】
（３）用紙搬送方向の用紙捌き部材の配置位置における上流側の用紙搬送路と前記当接部の接線方向との間に挟まれた範囲内に前記搬送補助部材の他端を固定することによって、上記給紙ローラの外周部に対する当接力を、用紙搬送方向における上流側から下流側に向かう方向に付与でき、用紙の厚みに応じて搬送補助部材が容易に押動されるので、用紙に当接力を一定に付与することができ、用紙の厚みに係わらず用紙の搬送力を一定に増加させることができる。
【図面の簡単な説明】
【図１】この発明の実施形態に係る給紙装置を適用した画像形成装置の構成を示す断面図である。
【図２】同給紙装置を適用した画像形成装置の一部の構成を拡大した断面図である。
【図３】同給紙装置を適用した画像形成装置の一部の構成を拡大した断面図である。
【図４】従来の給紙装置の構成を示した断面図である。
【図５】従来の給紙装置の構成を示した断面図である。
【符号の説明】
２５−給紙装置
２６−給紙ローラ
２７−用紙捌き部材
２８−搬送補助部材
２９−ガイド
１００−画像形成装置
Ｓ−用紙搬送路[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a sheet feeding device that conveys a sheet or a document stored or placed therein in an image forming apparatus such as a copying machine or a facsimile machine or an image reading and reading apparatus that reads an image on an image surface of a document.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, in an image reading apparatus, an image forming apparatus, or the like, a plurality of originals or papers stored or placed in a hopper or a paper feed tray are taken out one by one by rotating a pickup roller or a paper feed roller. The document is conveyed to a document reading unit and an image forming unit arranged on a paper conveyance path.
[0003]
In the above-described configuration, a plurality of stored sheets or the like may not be taken out one by one due to the frictional action between the sheets, but may be taken out several times. Therefore, in the conventional sheet feeding device, a separator roller that is pressed against the outer peripheral portion of the sheet feeding roller and is driven to rotate in a direction opposite to the sheet feeding roller is disposed, and the outer peripheral portion of the sheet feeding roller is pressed against the separator roller. In some cases, a sheet is conveyed to a printing section, and the paper is separated and conveyed one by one in the press contact section (for example, see Patent Document 1).
[0004]
Further, as shown in FIG. 4, a paper separating member 152 formed of an elastic member or the like is disposed so as to be in pressure contact with the outer peripheral portion of the paper feed roller 151, and the outer peripheral portion of the paper feed roller 151 and the paper separating member 152 are disposed. In some cases, a sheet is conveyed to a press contact portion, and the sheets are separated one by one and conveyed to a sheet conveyance path S at the press contact portion.
[0005]
However, in the configuration of Patent Document 1 described above, since the thickness of the paper is different between thin paper or plain paper (50 to 100 g / m ² ) and thick paper (128 g / m ² or more), the rotation axis is The load on the fixed separator roller is different, and the conveying force of the paper feed roller is different. That is, since the thickness differs depending on the type of paper, when passing through the pressure contact portion between the paper feed roller and the separator roller, the thicker paper is pressed by the pressure contact portion and the friction increases, so that the conveying force is larger than that of thin paper. Become. Further, since the separator roller rotates in reverse without being driven by the paper feed roller, it acts in a direction to suppress the paper conveyance force. The same applies to the configuration of the above-described paper feed roller 151 and the paper separating member 152.
[0006]
For this reason, in recent paper feeders, as shown in FIG. 5, an auxiliary roller 155 that comes into contact with the paper feed roller 151 is disposed downstream of the position where the paper separating member 152 is disposed in the paper transport direction. The auxiliary roller 155 has an elastic member 156 and applies an elastic force from the elastic member 156 to the outer peripheral portion of the paper feed roller 151 in a direction normal to a contact portion with the paper feed roller 151 as a contact force. . The rotation axis of the auxiliary roller 155 is movable in the normal direction. Thus, when the sheet passes through the contact portion between the sheet feeding roller 151 and the auxiliary roller 155, the sheet comes into contact with the sheet feeding roller 151, so that the conveying force is increased even for thin sheets, and sufficient conveying force is obtained. Will be retained.
[0007]
Further, a guide roller is provided on the guide surface of the guide member on the substantially U-shaped feeding path in side view, and the rear end of the sheet conveyed on the sheet conveyance path contacts the guide member to convey the sheet. It reduces the opposing force (also called back tension), regulates the angle of advance of the paper from the paper feed roller to the transport roller, increases the contact area between the paper and the transport roller, and transports the reaction force received from the paper. There is one that converts the pressing force of the driven roller to ensure that the paper is conveyed by the conveyance roller (see, for example, Patent Document 2).
[0008]
[Patent Document 1]
JP-A-2-13530 [Patent Document 2]
JP 2001-233497 A [Problems to be Solved by the Invention]
However, in the configuration in which the auxiliary roller 155 is arranged as shown in FIG. 5, when the sheet passes through the contact portion, the auxiliary roller 155 is pushed toward the elastic member 156 in the normal direction due to the thickness of the sheet. However, since the direction in which the elastic member 156 applies the elastic force is opposed to the direction in which the elastic member 156 applies the elastic force, it is difficult for the auxiliary roller 155 to be pushed by the thickness of the sheet. The reaction force from 156 is added to the contact force. Therefore, although the conveying force required to convey the sheet can be increased, when a thick sheet passes through the contact portion, a larger contact force is applied than a thin sheet, and the conveying force increases. Thus, it is difficult to apply a constant conveying force regardless of the thickness of the sheet. For this reason, the timing for feeding the sheet differs depending on the thickness of the sheet, and there is a possibility that a shift in the timing for feeding the sheet in the next process such as oblique conveyance or image formation may occur. Further, in order to increase the conveying force, a large space for arranging the auxiliary roller 155 for increasing the area where the sheet, which is the nip width at the contact portion, contacts the outer peripheral portion of the paper feed roller 151 must be secured. No.
[0009]
On the other hand, in the configuration of Patent Document 2 described above, a guide roller is provided on a substantially U-shaped feeding path in side view to reduce the back tension of the sheet, and the angle of entry when the sheet is conveyed from the sheet feeding roller to the conveying roller is reduced. Although the conveyance force of the sheet is increased by the regulation by the conveyance roller, the conveyance force of the sheet is not increased by the paper supply roller. Therefore, in the configuration of the sheet conveyance path S extending from the lower side to the upper side as shown in FIG. There is a possibility that sufficient conveyance force cannot be obtained.
[0010]
SUMMARY OF THE INVENTION It is an object of the present invention to provide a transport assisting member that abuts on the outer peripheral portion of a paper feed roller on the downstream side of an arrangement position of a paper separating member in a paper transport direction and suppresses a space required for arrangement, regardless of the thickness of the paper. It is an object of the present invention to provide a sheet feeding device capable of constantly increasing a sheet conveying force.
[0011]
[Means for Solving the Problems]
The present invention has the following configuration in order to solve the above problems.
[0012]
(1) In a sheet feeding device in which a sheet separating member that is in pressure contact with an outer peripheral portion of a sheet feeding roller that is rotationally driven on a sheet conveying path is arranged,
The outer peripheral portion of the paper feed roller contacts the outer peripheral portion of the paper feed roller downstream of the position where the paper separating member is disposed in the paper transport direction, and contacts the outer peripheral portion of the paper feed roller in a direction from the upstream side to the downstream side in the paper transport direction. A transport assisting member is provided which applies a contact force and is movable in a normal direction of a contact portion with the sheet feeding roller.
[0013]
In this configuration, in the sheet feeding device in which the sheet separating member that is in pressure contact with the outer peripheral portion of the sheet feeding roller is arranged on the sheet conveying path, the outer peripheral portion of the sheet feeding roller is located downstream of the position where the sheet separating member is arranged in the sheet conveying direction. Is applied to the outer peripheral portion of the paper feed roller in a direction from the upstream side to the downstream side in the sheet conveying direction. Therefore, a contact force when the outer peripheral portion of the paper feed roller is brought into contact with the transport auxiliary member is applied in a direction from the upstream side to the downstream side in the paper transport direction, so that the paper is fed to the paper feed roller and the transport auxiliary member. When the sheet passes through the contact portion, the transport assisting member is pushed in the direction opposite to the sheet feed roller side in the normal direction of the contact portion by the thickness of the sheet without affecting the contact force. Therefore, a reaction force from the conveyance assisting member to the thickness of the sheet is not applied, and a constant contact force is applied to the sheet depending on the thickness of the sheet.
[0014]
(2) The transport assisting member is formed of a thin plate member that is elastically deformed, and a contact surface of one end in contact with the paper feed roller has an arc shape, and the other end is fixed in the sheet transport direction. It is characterized by having.
[0015]
In this configuration, one end of the transport assisting member, which is formed of a thin plate member that is elastically deformed, is formed so as to contact the paper feed roller and the contact surface thereof is formed in an arc shape, and the other end is oriented in the paper transport direction. It is fixed for. Therefore, since the transfer assisting member is a thin plate member and the contact surface of the contact portion at one end of the transfer assisting member is formed in an arc shape, the space required for disposing the transfer assisting member does not increase, and The nip area of the contact portion does not become narrow.
[0016]
(3) The other end of the transport assisting member is fixed in a range sandwiched between the upstream paper transport path and the tangential direction of the contact portion at the position of the paper separating member in the paper transport direction. It is characterized by the following.
[0017]
In this configuration, the other end of the transport assisting member is fixed within a range sandwiched between the upstream paper transport path and the tangential direction of the contact portion at the position of the paper separating member in the paper transport direction. Therefore, the contact force against the outer peripheral portion of the paper feed roller is applied not in the normal direction of the contact portion but in the direction from the upstream side to the downstream side in the sheet transport direction. Therefore, when the sheet passes through the contact portion between the sheet feeding roller and one end of the transport assisting member, the contact force does not affect the sheet feeding roller side in the normal direction of the contact portion depending on the thickness of the sheet. The entire transport assisting member is elastically deformed so that one end of the transport assisting member is pushed in the opposite direction. Therefore, a reaction force from the conveyance assisting member to the thickness of the sheet is not applied, and a constant contact force is applied to the sheet depending on the thickness of the sheet.
[0018]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1 is a diagram illustrating a configuration of an image forming apparatus to which a sheet feeding device according to an embodiment of the present invention is applied. The image forming apparatus 100, which is a main body apparatus of the present invention, has a copier mode, a printer mode, and a facsimile mode as image forming modes for forming an image on paper (including a recording medium such as an OHP). Selected.
[0019]
The image forming apparatus 100 includes a document reading unit 10, a paper feeding unit 20, an image forming unit 30, a paper discharging unit 40, an operation panel unit (not shown), and the like. The document reading unit 10 is disposed at an upper portion of the apparatus main body, and includes a platen glass 11, a scanner optical system 12, and the like. The scanner optical system 12 includes a light source 13, a plurality of reflection mirrors 14a to 14c, an optical lens 15, and a charge coupled device (CCD) 16. The light source 13 irradiates light on a document placed on the platen glass 11. The plurality of reflection mirrors 14a to 14c reflect light reflected from the document and guide the light to the optical lens 15. The optical lens 15 condenses the reflected light guided by the reflection mirrors 14 a to 14 c and guides the light to the CCD 16. The CCD 16 photoelectrically converts the collected reflected light.
[0020]
The paper feeding unit 20 is disposed at a lower portion of the apparatus main body, and includes a paper feeding tray 21, a manual feed tray 22, a pickup roller 23, a paper feeding device 25, and the like. The sheet feed tray 21 and the manual feed tray 22 place sheets to be fed to the sheet transport path S during image formation. The pickup roller 23 feeds the paper placed on each of the trays 21 and 22 to the paper transport path S. The sheet feeding device 25 will be described later. The image forming section 30 is disposed on the side of the manual feed tray 22 below the document reading section 10, has a laser scanning unit (hereinafter, referred to as LSU) (not shown), a photosensitive drum 31, and a fixing device 36. Around the drum 31, a charger 32, a developing device 33, a transfer device 34, and a static eliminator 35 are arranged in this order along a direction of an arrow shown in FIG.
[0021]
The paper discharge unit 40 is disposed above the paper feed tray 21 and includes a paper discharge roller 41, a paper discharge tray 42, and the like. The paper discharge roller 41 discharges the paper on the paper conveyance path S on which the image formation has been completed to the paper discharge tray 42. The paper discharge tray 42 places the paper discharged from the paper discharge roller 41. The operation panel unit includes a plurality of input keys (not shown) for receiving inputs of various settings such as the number of prints and the print magnification.
[0022]
When copying an image of a document on paper in the copier mode, after placing a document to be copied on the platen glass 11 of the document reading unit 10, each input key provided on the operation panel unit is depressed, and the number of prints and the printing magnification are depressed. Then, a copy operation is started by pressing a start key (not shown).
[0023]
When the start key is pressed, the pickup roller 23 of the image forming apparatus 100 rotates, and the sheet is fed to the sheet transport path S. The fed paper is transported to registration rollers 51 provided on the paper transport path S.
[0024]
The leading end of the sheet conveyed to the registration roller 51 in the conveyance direction is aligned with the toner image formed on the photosensitive drum 31 to be transferred onto the sheet. Is held between the registration rollers 51 so that the axial direction of the pair is parallel.
[0025]
The image data read by the document reading unit 10 is subjected to image processing under conditions input using an input key or the like, and then transmitted to the LSU as print data. The LSU irradiates the surface of the photosensitive drum 31 charged to a predetermined potential by the charger 32 with a laser beam based on the image data through a polygon mirror and various lenses (not shown) to form an electrostatic latent image. . Thereafter, the toner, which is provided in a developing tank (not shown) of the developing device 33 and partially adheres to the surface of the MG roller 33 a facing the photosensitive drum 31, is exposed in accordance with the potential gap on the surface of the photosensitive drum 31. The electrostatic latent image is attracted to and adhered to the surface of the body drum 31, and the electrostatic latent image is visualized. The toner remaining on the photosensitive drum 31 is scraped off by a cleaning blade of a drum unit (not shown), and is collected by a cleaner unit (not shown).
[0026]
Thereafter, the registration roller 51 aligns the paper sandwiched between the registration rollers 51 with the toner image formed on the surface of the photoconductor drum 31, and moves the paper between the photoconductor drum 31 and the transfer device 34. Transport. Next, the toner image on the surface of the photosensitive drum 31 is transferred to the sheet by using the transfer roller 34a provided in the transfer device 34. The paper on which the transfer of the toner image has been completed passes between the upper heat roller 36a and the lower heat roller 36b of the fixing device 36, so that heat and pressure are applied, and the toner image is melted and fixed. Is discharged to a discharge tray 42 by a discharge roller 41.
[0027]
FIG. 2 is an enlarged cross-sectional view of a part of the configuration of the image forming apparatus to which the sheet feeding device according to the embodiment of the present invention is applied. As shown in FIG. 2, a sheet feeding device 25 for conveying the sheet taken out to the sheet conveyance path S by the pickup roller 23 to an image forming unit 30 or the like arranged on the sheet conveyance path S includes a sheet conveyance device. It is composed of a paper feed roller 26, a paper separating member 27, a transport auxiliary member 28 and the like arranged on the path S. The paper feed roller 26 is driven to rotate counterclockwise, and conveys the sheet in the direction of arrow X that is the sheet conveyance direction. The sheet separating member 27 has an elastic member 27 a and presses against the outer peripheral portion of the sheet feeding roller 26. Further, the sheet separating member 27 separates the sheets so that the sheets are conveyed one by one when a plurality of superposed sheets are conveyed to the pressure contact portion with the sheet feeding roller.
[0028]
The transport assisting member 28 is made of an elastically deformable thin plate member, one end of which is in contact with the paper feed roller 26 by the elastic force of the elastic deformation, and the other end is fixed to a guide 29 which regulates the sheet in the arrow X direction. Further, the conveyance assisting member 28 applies a contact force to the contact portion with the paper feed roller 26 in the direction of arrow Y that is inclined in the direction of arrow X with respect to the normal direction of the contact portion. To help increase. In other words, when the sheet passes through the contact portion, the sheet is brought into contact with a sheet feeding roller 26 that applies a conveying force to the sheet by rotating the sheet, thereby increasing the friction between the sheet and the sheet feeding roller 26 to thereby increase the conveying force. Increase.
[0029]
In the above case, depending on the thickness of the sheet, a force in the direction of the arrow Z which is opposite to the direction of the sheet feed roller 26 in the normal direction is applied to the contact surface of the contact portion at one end of the transport assist member 28, Is elastically deformed such that one end is pushed in the arrow Z direction. Here, since the contact force does not act in the direction opposite to the direction of the arrow Z, the conveyance assisting member 28 is easily elastically deformed depending on the thickness even when conveying a sheet having a different thickness. Accordingly, the reaction force from the transport assisting member 28 with respect to the thickness of the sheet does not add to the contact force, and the contact force can be applied to the sheet irrespective of the thickness of the sheet. Can be done.
[0030]
At one end of the transport assisting member 28, a contact surface of a contact portion with the paper feed roller 26 is formed in an arc shape. As a result, the nip area of the contact portion is increased as compared with the case where the contact surface has a planar shape, and the area of contact with the sheet can be increased, so that the friction between the sheet feed roller 26 and the sheet increases, The conveying force can be efficiently increased.
[0031]
As described above, in the paper feeding device 25 according to the embodiment of the present invention, one end having the arc shape is brought into contact with the outer peripheral portion of the paper feeding roller on the downstream side of the arrangement position of the paper separating member 27 in the arrow X direction, When the sheet passes through the contact portion, the conveyance assisting member 28 having the other end fixed to the guide 29 applies a contact force to the outer peripheral portion of the sheet feeding roller 26 in the arrow Y direction. Regardless of the thickness, the transport force can be increased steadily.
[0032]
Further, by forming the transfer assisting member 28 as a thin plate member and forming the contact surface of the contact portion at one end of the transfer assisting member 28 in an arc shape, the space required for disposing the transfer assisting member 28 can be suppressed. The nip width of the contact portion can be increased, and the transport force can be increased.
[0033]
In addition, the fixing position of the other end of the transport assisting member 28 of the present invention is fixed to the guide 29, but is not particularly limited to this. If the contact force is within the range of the hatched portion shown in FIG. 3 sandwiched between the upstream sheet transport path S and the tangential direction of the contact portion at the position of the sheet separating member 27 in the arrow X direction, The applying direction is not opposite to the arrow Z direction, and the contact force can be applied to the outer peripheral portion of the sheet feeding roller 26 in a direction from the upstream side to the downstream side in the arrow X direction. Obtainable.
[0034]
Further, the present invention is not limited to the paper feeding device provided in the image forming apparatus, but is also applicable to a device for transporting a sheet or a document such as a facsimile device and an image reading device.
[0035]
【The invention's effect】
According to the present invention, the following effects can be obtained.
[0036]
(1) The transport assisting member abuts on the outer peripheral portion of the paper feed roller at the downstream side of the position where the paper separating member is disposed in the paper transport direction, and from the upstream side to the downstream side in the paper transport direction with respect to the outer peripheral portion of the paper feed roller. By applying the contact force in the direction toward the paper, the conveyance assisting member is easily pushed in accordance with the thickness of the sheet, so that the contact force can be applied to the sheet uniformly, regardless of the thickness of the sheet. The conveying force can be increased steadily.
[0037]
(2) It is necessary to arrange the transport assisting member by forming the one end of the transport assisting member with an elastically deformed thin plate member so as to abut against the paper feed roller and forming the contact surface in an arc shape. The nip width of the contact portion can be increased while suppressing a small space, and the transport force can be increased.
[0038]
(3) By fixing the other end of the transport assisting member in a range sandwiched between the upstream paper transport path and the tangential direction of the contact portion at the position of the paper separating member in the paper transport direction. The contact force against the outer peripheral portion of the paper feed roller can be applied in a direction from the upstream side to the downstream side in the paper transport direction, and the transport auxiliary member can be easily pushed according to the thickness of the paper. The contact force can be given constant, and the sheet conveying force can be constantly increased irrespective of the thickness of the sheet.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view illustrating a configuration of an image forming apparatus to which a sheet feeding device according to an embodiment of the present invention is applied.
FIG. 2 is an enlarged cross-sectional view of a part of the configuration of an image forming apparatus to which the sheet feeding device is applied.
FIG. 3 is an enlarged cross-sectional view of a part of the configuration of an image forming apparatus to which the sheet feeding device is applied.
FIG. 4 is a cross-sectional view illustrating a configuration of a conventional sheet feeding device.
FIG. 5 is a cross-sectional view illustrating a configuration of a conventional sheet feeding device.
[Explanation of symbols]
25-sheet feeding device 26-sheet feeding roller 27-sheet separating member 28-conveying auxiliary member 29-guide 100-image forming apparatus S-sheet conveying path

Claims

In a sheet feeding device in which a sheet separating member that is in pressure contact with an outer peripheral portion of a sheet feeding roller that is rotationally driven on a sheet conveying path is arranged,
The outer peripheral portion of the paper feed roller contacts the outer peripheral portion of the paper feed roller downstream of the position where the paper separating member is disposed in the paper transport direction, and contacts the outer peripheral portion of the paper feed roller in a direction from the upstream side to the downstream side in the paper transport direction. A sheet feeding device, comprising: a transfer assisting member that applies a contact force and is movable in a normal direction of a contact portion with a sheet feeding roller.

The conveyance assisting member is formed of a thin plate member that is elastically deformed, and a contact surface of a contact portion with one end of the sheet feeding roller has an arc shape, and the other end is fixed in a sheet conveyance direction. The sheet feeding device according to claim 1, wherein

The other end of the transport assisting member is fixed in a range sandwiched between an upstream paper transport path and a tangential direction of the contact portion at a position where the paper separating member is arranged in the paper transport direction. The sheet feeding device according to claim 2, wherein: