JP3795548B2

JP3795548B2 - Paper feeder

Info

Publication number: JP3795548B2
Application number: JP07778695A
Authority: JP
Inventors: 克彦三木
Original assignee: Ricoh Co Ltd
Current assignee: Ricoh Co Ltd
Priority date: 1995-04-03
Filing date: 1995-04-03
Publication date: 2006-07-12
Anticipated expiration: 2021-07-12
Also published as: JPH08268572A

Description

【０００１】
【産業上の利用分野】
本発明は、複写機、ファクシミリ、レーザプリンタ等の画像形成装置に適用される、給紙カセット等に収容された用紙束から用紙を１枚ずつ分離して給紙する装置に関するものである。
【０００２】
【従来の技術】
画像形成装置において、用紙束から用紙を１枚ずつ分離する機構として、例えば摩擦を利用する方式が広く知られている。この方式では、分離すべき用紙束の一番上の用紙を繰り出し、他の用紙を用紙束に残すために、用紙を弛ませたり、摩擦ローラ（呼び出しローラ）と摩擦部材の擦り動作を用いている。そのために、分離すべき用紙を繰り出すための部材（給紙コロ、呼び出しローラ）と、当該用紙に伴って繰り出されかけた他の用紙の搬送、所謂重送を阻止する部材（コーナー爪、摩擦パッド、摩擦ローラ）とを基本部材としている。
【０００３】
このような方式を含む多くの給紙装置では、用紙載置台たる底板に積載された用紙束から最初の用紙を呼び出すためのローラ（給紙コロ、呼び出しローラ）に当該用紙束を押し付ける加圧機構を備えたものがある。図６（ａ）に示されるように、底板２０は底板支点２１を中心に上下揺動し、その自由端側がカセット乃至トレイの先端コーナー爪２２に突き当たるようになっている。図の簡略化のために底板２０上に載置される用紙束は省略しているが、レバー軸２３を中心に加圧レバー２４が上下揺動し、その自由端で底板２０を押し上げ、当該底板２０上の用紙束を半月状給紙コロ２５に押し付け可能とする。相当量の用紙束が底板２０にある場合には、用紙束最上位の用紙が給紙コロ２５に容易に当接するが、給紙作業が進み、用紙の追加を行わないでいると、用紙束最上位の用紙を給紙コロ２５に当接するためには、加圧レバー２４がかなり持ち上がらなければならない。加圧レバー２４が持ち上がると、当該加圧レバー２４と底板２０の当接角θが大きくなる。図６（ｂ）で理解されるように、当接角θが大きいと加圧レバー２４の力Ｐ_fのうち底板加圧成分の割合が減り、底板２０の接触部における摺動抵抗もあって、必要な底板加圧を行うために加圧レバー軸のトルクが急激に大きくなる。場合によっては給紙コロ２５への給紙圧Ｐ_sが不足したりして、重送や不送りの原因ともなる。
【０００４】
特に図示のように給紙コロ２５が半月状に形成されている場合には、カセット乃至トレイからの給紙時に底板２０が上下動する。この上下動に際して、当接角θが大きい場合、その摺動抵抗も含め、加圧レバー２４から底板２０への力Ｐ_fの作用方向と底板の上下動による加圧レバーへの力Ｐ_mの作用方向に大きなズレが生じ、底板２０を下げる力と上げる力に大きな差ができる可能性があり、給紙圧Ｐ_sがねらい通りに得られにくくなり、重送や不送りが発生しやすくなる。
【０００５】
【発明が解決しようとする課題】
そこで例えば特開昭６０−４８８３９号公報で教示されている、厚みが異なるスペーサを予め複数個作製しておき、このスペーサを用紙サイズに応じて選択して底板に取り付け、そのスペーサの厚みの分だけ用紙の最上面の位置を変化させる提案を利用して、用紙束の厚みに応じて各種スペーサを底板に選択的に取り付け、加圧レバーの底板への力Ｐ_fの作用方向を安定させることも考えられる。
【０００６】
しかしながら、このような調整は、経時的に変化する用紙束の厚みに対してその都度適当なスペーサを選択取付しなければならず、作業的に面倒で実用的でない。
【０００７】
そこで本発明は、従来の不具合に鑑み、加圧レバーによる底板押し上げをスムーズに安定化させた給紙装置を提供することを課題とする。
【０００８】
【課題を解決するための手段】
上記課題を解決するために、本発明にしたがい、用紙束を載置するための用紙載置板と、当該用紙載置板上の用紙を半月状の用紙繰り出しローラに押し付けるための用紙載置板持ち上げ機構とを有する給紙装置において、上記持ち上げ機構が上下揺動する部材を有し、当該揺動部材と用紙載置板の間に、給紙方向と逆向きに次第に厚みが増大するような押し当て部材を介在させ、次第に厚みが増大する押し当て部材によって用紙載置板と揺動部材とで形成される当接角が小さくなるように構成される。
【０００９】
用紙繰り出しローラが用紙載置板の幅方向に複数個配置されている場合には、押し当て部材が、用紙載置板の幅方向中央に設けられているのが好ましい。
【００１０】
【実施例】
本発明の詳細を、図に示された実施例に基づいて、以下に説明する。
図１において、不図示のカセット乃至トレイ内に配置され回動軸（図示せず）を支点として上下動自在な底板１の下面側に、加圧レバー軸４を中心に上下揺動する加圧レバー２が位置している。その自由端に取り付けられたコロ８に接触する領域において、底板下面に傾斜のついた押し当て部材７が取り付けられている。当該押し当て部材７の傾斜は、給紙方向と逆向きに次第に厚みが増大するように付けられており、図２に示されるように、当該押し当て部材７がない場合の底板１と加圧レバー２との当接角θと、押し当て部材７によって修正される当接角αとが常にθ＞αの関係を有しており、しかもαをできるだけ小さくすることによって、加圧レバー２の摺動抵抗を小さくでき、底板１への加圧をスムーズにすることができる。また底板１を押し下げる力と加圧レバー２による底板１を上に押し上げる力が近似することともなる。ただし、図示のように当該押し当て部材７の曲線は曲線的なものに限られず、直線的であっても、一定の効果を奏することはもちろんである。また当該押し当て部材７は、図３に示されるように、幅方向に対称になるよう底板１を切り曲げることによって作り出すことができる。また図４に示されるように、合成樹脂等で予め傾斜押し当て部材７を成形した上で底板１の下面に貼着してもよい。
【００１１】
図１に戻り、加圧レバー軸４の一端には更にアーム３が固着され、また当該アーム３の反対側先端部には、一端を機体に取り付けられたスプリング５の他端が繋がれている。底板１上に充分な量の用紙束６がある場合には、加圧レバー２が底板１を押し上げなくとも、その最上位の用紙は呼び出し状態にある半月状給紙コロ７に当接可能である。したがって、この状態で加圧レバー２のコロ８と接触する押し当て部材７の領域は傾斜を有する必要がない。
【００１２】
これに対して、次第に用紙束６の量が減って、加圧レバー２による底板１上昇の程度が大きくなってくると、図２に示されるように、スプリング５の引っ張り力によって加圧レバー２は揺動上昇し、そのコロ８は押し当て部材７の傾斜面に沿って給紙方向と逆向きに移動する。押し当て部材７の傾斜面によって当接角αは僅かであり、その結果、給紙時に給紙コロ９によって底板１を押し下げる力の作用方向と加圧レバー２によって底板１を上に押し上げる力の作用方向のズレは小さく収まっている。
【００１３】
上記のように、押し当て部材７は底板１の幅方向において対称的に複数個配設されてもよいが、給紙コロ９が複数個設けられている場合には、各部品の製造誤差に基づくバラツキの積み上げによって底板１と各給紙コロ９の間の隔たりは正確に同一となりがたく、複数個所の底板押し上げ機構を用いて底板を押し上げると各給紙コロへの押し付け力が均一にならず、給紙コロと用紙との摩擦力が一様でなくなり、スキューを生じたりする。そこで図５に示されるように、押し当て部材７を、底板１の幅方向における中央１ケ所のみに取り付けるようにする。加圧レバー２が加圧レバー軸４を中心に揺動上昇し、押し当て部材７に沿ってコロ８が移動して底板１を持ち上げると、底板上に載置された不図示の用紙は給紙コロ９によって給紙搬送可能となるが、その際、底板持ち上げを底板の幅方向中央のみで行うので、最上位の用紙と各給紙コロ９の当接圧は均一になる。即ち、中央１ケ所のみの加圧により、各給紙コロでの等しい当接圧に分散し、給紙コロ９と用紙との摩擦力乃至用紙搬送力が均一となる。
【００１４】
【発明の効果】
請求項１に記載の給紙装置によれば、持ち上げ機構が上下揺動する部材を有し、当該揺動部材と用紙載置板の間に、給紙方向と逆向きに次第に厚みが増大するような押し上げ部材が介在するように構成されているので、載置する用紙束の量が減るにつれて増大する押し当て部材の傾斜の分だけ用紙載置板と揺動部材での当接角が小さくなり、給紙の際に用紙載置板を押し上げる力の作用方向と用紙載置板を持ち上げる力の作用方向とでズレが少なく、用紙載置板の加圧を適切に行うことが可能となる。また揺動部材の用紙載置板に対する摺動もスムーズとなる。
【００１５】
請求項２に記載の給紙装置によれば、押し当て部材が、用紙載置板の幅方向中央に設けられるので、用紙繰り出しローラが用紙載置板の幅方向に複数個配置されている場合、請求項１の効果に加えて、各繰り出しローラへの加圧を均一化でき、ローラへの偏圧によるスキュー等を防止できる。
【図面の簡単な説明】
【図１】本発明に係る給紙装置での用紙満載状態を示す部分概略図である。
【図２】図１に対応し用紙積載量が少なくなった状態を示す部分概略図である。
【図３】押し当て部材の取付状態を説明する部分概略図である。
【図４】図３とは異なる押し当て部材の取付状態を説明する部分概略図である。
【図５】底板中央に押し当て部材を取り付けた状態を示す部分概略図である。
【図６】積載用紙を給紙コロに押し付けるための従来公知の加圧機構を説明する図で、（ｂ）は（ａ）を部分拡大したものであり、特に圧力の作用方向を説明するものである。
【符号の説明】
１底板
２加圧レバー
４加圧レバー軸
７押し当て部材
８コロ
９給紙コロ[0001]
[Industrial application fields]
The present invention relates to an apparatus that is applied to an image forming apparatus such as a copying machine, a facsimile machine, or a laser printer and separates and feeds sheets one by one from a sheet bundle stored in a sheet feeding cassette or the like.
[0002]
[Prior art]
In an image forming apparatus, as a mechanism for separating sheets from a sheet bundle one by one, for example, a system using friction is widely known. In this method, in order to feed out the top sheet of the sheet bundle to be separated and leave other sheets in the sheet bundle, the sheet is loosened or the friction roller (calling roller) and the friction member are rubbed. Yes. For this purpose, members (feed rollers, call rollers) for feeding out the paper to be separated, and members (corner pawls, friction pads) that prevent the so-called double feed of other paper that has been fed out along with the paper. , Friction roller) as a basic member.
[0003]
In many paper feeding apparatuses including such a method, a pressure mechanism that presses the paper bundle against a roller (paper feeding roller, calling roller) for calling the first paper from the paper bundle stacked on the bottom plate serving as a paper placement table. There is something with. As shown in FIG. 6A, the bottom plate 20 swings up and down around the bottom plate fulcrum 21 so that the free end of the bottom plate 20 abuts against the corner claw 22 at the front end of the cassette or tray. For the sake of simplification, the sheet bundle placed on the bottom plate 20 is omitted, but the pressure lever 24 swings up and down around the lever shaft 23 and pushes up the bottom plate 20 at its free end. The sheet bundle on the bottom plate 20 can be pressed against the half-moon-shaped sheet feeding roller 25. When a considerable amount of paper bundles are present on the bottom plate 20, the uppermost paper of the paper bundle easily comes into contact with the paper feeding roller 25. However, if the paper feeding operation proceeds and no paper is added, the paper bundle In order to bring the uppermost sheet into contact with the sheet feeding roller 25, the pressure lever 24 must be lifted considerably. When the pressure lever 24 is lifted, the contact angle θ between the pressure lever 24 and the bottom plate 20 increases. As understood from FIG. 6B, when the contact angle θ is large, the ratio of the bottom plate pressure component to the force P _f of the pressure lever 24 decreases, and there is a sliding resistance at the contact portion of the bottom plate 20. In order to perform the necessary bottom plate pressurization, the torque of the pressure lever shaft increases rapidly. In some cases, the sheet feeding pressure P _s to the sheet feeding roller 25 is insufficient, causing double feeding or non-feeding.
[0004]
In particular, when the sheet feeding roller 25 is formed in a half-moon shape as shown in the drawing, the bottom plate 20 moves up and down during sheet feeding from a cassette or tray. When the contact angle θ is large during this vertical movement, including the sliding resistance, the direction of action of the force P _f from the pressure lever 24 to the bottom plate 20 and the force P _m to the pressure lever due to the vertical movement of the bottom plate There is a possibility that a large deviation occurs in the acting direction, and there is a possibility that a large difference can be made between the force for lowering and raising the bottom plate 20, and it becomes difficult to obtain the sheet feeding pressure P _s as intended, and double feed and non-feed are likely to occur. .
[0005]
[Problems to be solved by the invention]
Therefore, for example, a plurality of spacers having different thicknesses taught in JP-A-60-48839 are prepared in advance, and the spacers are selected according to the paper size and attached to the bottom plate. By using the proposal to change the position of the top surface of the paper only, various spacers are selectively attached to the bottom plate according to the thickness of the paper bundle, and the acting direction of the force P _f to the bottom plate of the pressure lever is stabilized Is also possible.
[0006]
However, such adjustment requires selective mounting of appropriate spacers each time for the thickness of the sheet bundle that changes over time, which is cumbersome and impractical for work.
[0007]
Accordingly, an object of the present invention is to provide a paper feeding device that smoothly stabilizes the pushing up of the bottom plate by the pressure lever in view of the conventional problems.
[0008]
[Means for Solving the Problems]
In order to solve the above-described problems, according to the present invention, a paper placement plate for placing a bundle of paper and a paper placement plate for pressing the paper on the paper placement plate against a half-moon-shaped paper feed roller In a paper feeding device having a lifting mechanism, the lifting mechanism has a member that swings up and down, and a pressing is performed between the swinging member and the paper placing plate so that the thickness gradually increases in the direction opposite to the paper feeding direction. The abutting angle formed between the sheet placing plate and the swing member is configured to be small by the pressing member that gradually increases in thickness with the member interposed .
[0009]
In the case where a plurality of sheet feeding rollers are arranged in the width direction of the sheet placing plate, it is preferable that the pressing member is provided at the center in the width direction of the sheet placing plate.
[0010]
【Example】
The details of the present invention will be described below based on the embodiments shown in the drawings.
In FIG. 1, a pressurization that swings up and down around a pressure lever shaft 4 on the lower surface side of a bottom plate 1 that is arranged in a cassette or tray (not shown) and that can move up and down with a rotation shaft (not shown) as a fulcrum. The lever 2 is located. In a region where the roller 8 attached to the free end contacts the roller 8, a pressing member 7 having an inclined bottom plate is attached. The inclination of the pressing member 7 is attached so that the thickness gradually increases in the direction opposite to the paper feeding direction. As shown in FIG. The contact angle θ with the lever 2 and the contact angle α corrected by the pressing member 7 always have a relationship of θ> α, and by making α as small as possible, the pressure lever 2 A sliding resistance can be made small and the pressurization to the baseplate 1 can be made smooth. Further, the force for pushing down the bottom plate 1 and the force for pushing up the bottom plate 1 by the pressure lever 2 are also approximated. However, as shown in the drawing, the curve of the pressing member 7 is not limited to a curved one, and it goes without saying that a certain effect can be obtained even if it is linear. Further, as shown in FIG. 3, the pressing member 7 can be produced by cutting and bending the bottom plate 1 so as to be symmetrical in the width direction. Further, as shown in FIG. 4, the inclined pressing member 7 may be formed in advance with a synthetic resin or the like and then attached to the lower surface of the bottom plate 1.
[0011]
Returning to FIG. 1, the arm 3 is further fixed to one end of the pressure lever shaft 4, and the other end of the spring 5 having one end attached to the body is connected to the opposite end of the arm 3. . When there is a sufficient amount of sheet bundle 6 on the bottom plate 1, the uppermost sheet can be brought into contact with the half-moon-shaped sheet feeding roller 7 in the calling state without the pressure lever 2 pushing up the bottom plate 1. is there. Therefore, the region of the pressing member 7 that contacts the roller 8 of the pressure lever 2 in this state does not need to have an inclination.
[0012]
On the other hand, when the amount of the sheet bundle 6 gradually decreases and the extent of the bottom plate 1 ascending by the pressure lever 2 increases, the pressure lever 2 is pulled by the pulling force of the spring 5 as shown in FIG. The roller 8 moves up and down, and the roller 8 moves along the inclined surface of the pressing member 7 in the direction opposite to the paper feeding direction. The contact angle α is small due to the inclined surface of the pressing member 7, and as a result, the direction of the action of pushing down the bottom plate 1 by the paper feed roller 9 during feeding and the force of pushing up the bottom plate 1 by the pressure lever 2 The deviation in the direction of action is small.
[0013]
As described above, a plurality of pressing members 7 may be arranged symmetrically in the width direction of the bottom plate 1. However, when a plurality of paper feeding rollers 9 are provided, a manufacturing error of each component is caused. The gap between the bottom plate 1 and each paper feed roller 9 is not exactly the same due to the accumulated variation, and when the bottom plate is pushed up using a plurality of bottom plate push-up mechanisms, the pressing force to each paper feed roller becomes uniform. Therefore, the frictional force between the paper supply roller and the paper is not uniform, and skew is generated. Therefore, as shown in FIG. 5, the pressing member 7 is attached only at one central position in the width direction of the bottom plate 1. When the pressure lever 2 swings and rises around the pressure lever shaft 4 and the roller 8 moves along the pressing member 7 to lift the bottom plate 1, the paper (not shown) placed on the bottom plate is fed. Paper feeding can be performed by the paper rollers 9, but the bottom plate is lifted only at the center in the width direction of the bottom plate, so that the contact pressure between the uppermost paper and each paper feeding roller 9 becomes uniform. That is, the pressure at only one central portion disperses the same contact pressure in each paper feed roller, and the frictional force or paper transport force between the paper feed roller 9 and the paper becomes uniform.
[0014]
【The invention's effect】
According to the sheet feeding device of the first aspect, the lifting mechanism has a member that swings up and down, and the thickness gradually increases in the direction opposite to the sheet feeding direction between the swinging member and the sheet placing plate. Since the push-up member is interposed, the contact angle between the paper placement plate and the swinging member is reduced by the amount of inclination of the pressing member that increases as the amount of paper bundles to be placed decreases . less deviation in the direction of action of the force to lift the acting direction and the sheet placing plate of the force pushing up the sheet placing plate during paper feed, it is possible to perform the pressurization of the paper table properly. Further, the sliding of the swinging member with respect to the paper placing plate becomes smooth.
[0015]
According to the paper feeding device of the second aspect, since the pressing member is provided at the center in the width direction of the paper placing plate, a plurality of paper feeding rollers are arranged in the width direction of the paper placing plate. In addition to the effects of the first aspect, the pressure applied to each feeding roller can be made uniform, and the skew and the like due to the bias pressure on the roller can be prevented.
[Brief description of the drawings]
FIG. 1 is a partial schematic diagram illustrating a full sheet state in a paper feeding device according to the present invention.
FIG. 2 is a partial schematic diagram illustrating a state in which the paper stacking amount is reduced corresponding to FIG. 1;
FIG. 3 is a partial schematic diagram for explaining a mounting state of a pressing member.
FIG. 4 is a partial schematic diagram for explaining a mounting state of a pressing member different from FIG. 3;
FIG. 5 is a partial schematic view showing a state in which a pressing member is attached to the center of the bottom plate.
FIG. 6 is a view for explaining a conventionally known pressurizing mechanism for pressing a loaded paper against a paper feed roller, and FIG. 6B is a partially enlarged view of FIG. It is.
[Explanation of symbols]
1 Bottom plate 2 Pressure lever 4 Pressure lever shaft 7 Pressing member 8 Roll 9 Paper feed roller

Claims

In a paper feeder having a paper placement plate for placing a bundle of paper and a paper placement plate lifting mechanism for pressing the paper on the paper placement plate against a half-moon-shaped paper feed roller,
The lifting mechanism has a member that swings up and down, and a pressing member that gradually increases in thickness in the direction opposite to the paper feeding direction is interposed between the swinging member and the paper placing plate, and the thickness gradually increases. The sheet feeding device, wherein a contact angle formed by the sheet placing plate and the swing member is reduced by the pressing member .

The sheet feeding device according to claim 1, wherein the pressing member is provided at a center in a width direction of the sheet placing plate.