JP3907490B2

JP3907490B2 - Image forming apparatus

Info

Publication number: JP3907490B2
Application number: JP2002031545A
Authority: JP
Inventors: 徳明福邊
Original assignee: Ricoh Co Ltd
Current assignee: Ricoh Co Ltd
Priority date: 2002-02-07
Filing date: 2002-02-07
Publication date: 2007-04-18
Anticipated expiration: 2022-02-07
Also published as: JP2003237985A

Description

【０００１】
【発明の属する技術分野】
本発明はプリンタ、ＦＡＸまたはそれらの複合機などの画像形成装置に関するものである。
【０００２】
【従来の技術】
最近の画像形成装置においては装置の小型化および生産性の向上が求められているため、給紙位置から用紙に画像が形成される転写位置までの用紙搬送距離が短いものが多い。通常、作像の開始は用紙積載手段の用紙の有無を確認してからスタートすることが好ましいが、このような画像形成装置の場合特に生産性の向上のため、連続して画像印刷を行う際は次の用紙の有無を確認する前に前の用紙の転写を行いながら次の作像の開始を行う場合が多々ある。
【０００３】
用紙の有無を検出する手段は用紙積載手段の出口近傍に設けられているので、前の用紙後端が用紙積載手段内にいる間は次の用紙の有無が確認できないため、上記のような動作を行わなければならない。作像を開始した後に用紙の無いことが判明した場合は当然その作像中の画像は印刷できないことになるため、それに要したトナーが全くの無駄になることはもちろん、画像形成部に残った未転写トナーを清掃する工程などが発生するため、感光体等寿命部品の不必要な消耗による劣化やその工程に要する余分な電力消費などを招く。
【０００４】
【発明が解決しようとする課題】
本発明では上記従来技術の問題点に鑑み、用紙検出手段を最小用紙サイズの後端近傍位置で検出することで最終紙の検出を早くし、無駄な作像工程を行わないことでトナー消費や装置の劣化、電力消費を押さえた画像形成装置を提供することを第一の目的とする。
【０００５】
また、本発明では、傾斜型底板を有する用紙積載手段に合わせ、更に底板検知手段との検知信号の組み合わせにより４段階の用紙残量状態の検知を可能とする画像形成装置を提供することを第二の目的とする。
【０００６】
また更に、本発明では、用紙搬送方向とトレイ挿抜方向が直行する構成の給紙手段においては、用紙検出手段を構成する用紙検知フィラーを待避する手段を設け、かつトレイの引き抜き時に用紙検出フィラーが待避することで、トレイの挿抜による用紙検出フィラーの破損や、用紙検出フィラーを避けるためにトレイの壁肉を減じることによる強度の減少を防止し得るようにした画像形成装置を提供することを第三の目的とする。
【０００７】
【課題を解決するための手段】
上記目的を達成するため、請求項１の発明は、用紙を積載する用紙積載手段と、前記用紙を一枚ずつ分離し画像形成部へ送る給紙手段と、該給紙手段に対して用紙を当接させもしくは所定位置へ上昇制御する用紙支持手段と、前記用紙積載手段内の用紙の有無を検知する用紙検知手段とを備えた画像形成装置において、前記用紙検知手段は、用紙積載手段に積載可能な用紙サイズの内、最小サイズの用紙の後端近傍を検知し得るよう構成したことを特徴とする画像形成装置を最も主要な特徴とする。
【０００８】
請求項２の発明は、用紙支持手段は所定の軸心を回転中心として斜めに用紙を支持する底板と、該底板の先端が所定の高さにあることを検知する底板検知手段を備え、用紙検知手段は用紙が所定高さ以上ある時と用紙無しの時とで同じ信号を発するよう構成した画像形成装置を特徴とする。
【０００９】
請求項３の発明は、用紙積載手段は装置本体より用紙搬送方向と直行する方向に挿抜可能に設けられ、用紙支持手段は所定の軸心を回転中心として斜めに用紙を支持する底板を備え、用紙検知手段は用紙上面に当接するフィラーを備え、前記底板には前記フィラーが落ち込む穴形状を有し、かつ、用紙積載手段を装置本体より引き抜くときに前記フィラーを非機能状態に待避させ、用紙積載手段を給紙位置にセットした時に前記フィラーを機能状態とする待避手段を設けた画像形成装置を特徴とする。
【００１０】
本発明によれば、用紙検出手段を最小用紙サイズの後端近傍位置で検出することで最終紙の検出を早くし、無駄な作像工程を行わないことでトナー消費や装置の劣化、電力消費を押さえることができ、傾斜型の底板を有する用紙積載手段に合わせ、更に底板検知手段との検知信号の組み合わせにより４段階の用紙残量状態の検知を可能とし、使用者に対しより詳細な状態を告知でき、使用勝手が良好となり、また更に、用紙搬送方向とトレイ挿抜方向が直行する構成の給紙装置を設けた場合には、用紙検出手段を構成するフィラーを待避する手段を設け、かつトレイの引き抜き時に用紙検出フィラーが待避することで、トレイの挿抜によるフィラーの破損や、フィラーを避けるためにトレイの壁肉を減じることによる強度の減少を防ぐことができる。
【００１１】
【発明の実施の形態】
以下、本発明の実施の形態を図示例と共に説明する。図１に本発明の画像形成装置の概略断面図を示す。給紙トレイ１００に積載された用紙１０１は給紙部１０２によって一枚ずつに分離され画像形成部１０３の転写部１０４へ搬送される。転写部１０４で表面に画像を転写された用紙は定着１０５へ搬送され、画像を定着された後排紙部１０６にて機外へ排出される。一方、画像の形成は画像形成部１０３内の書込部１０７で感光体１０８に潜像を作像し、現像部１０９にて潜像にトナーを付着させ転写部１０４で用紙と一緒となる。
【００１２】
給紙トレイ１００は装置本体に対し挿抜可能に構成され、用紙１０１の搬送方向とは直行する方向に抜き差しされる。給紙トレイ１００内には底板１が設けられ支点１ａを中心として回動自在に支持されている。底板１の下側にはスプリング２が設けられ、用紙１０１を給紙コロ３へと所定の圧力で当接させる。
【００１３】
また、底板１の中央付近上方には透過型フォトインタラプタ４ａと用紙検知フィラー４ｂで構成された用紙検知手段４が設けられており、用紙検知フィラー４ｂの先端は底板１に設けられた穴部１ｂに自重にて落ち込むよう構成されている。底板１の穴部１ｂは給紙トレイ１００に積載可能な用紙サイズのうち最も小さなサイズ（ここでいう最小サイズとは搬送方向に最も短いサイズをいう）の用紙後端近傍に位置し、底板１上に用紙１０１がある時には用紙検知フィラー４ｂ先端は用紙上面に当接する。
【００１４】
図１に示すような画像形成装置の場合、転写部１０４から給紙部１０２までの長さをＬ１、給紙部１０２から用紙検知位置までの長さをＬ２、同様に転写部１０４を起点として作像開始点となる書込部１０７までの、感光体１０８円周方向の長さをＬ３としたとき、（Ｌ１＋Ｌ２）＞Ｌ３の関係が満たされないと用紙の有無の確認が出来ないうちに次の作像を開始しなければならなくなる。
【００１５】
前述したような作像の無駄を発生させないためには、次の作像までのインターバル時間を設け用紙の有無が検知された後にその作像を開始することとなるが、その場合はインターバル時間分の余計な時間がかかるため、印刷生産性が著しく悪くなってしまう。よって本図示例ではＬ２をなるべく大きくするようにして、最少サイズ紙後端近傍で用紙検知を行っている。
【００１６】
更に図２で示すように、底板１の先端奥側上方には透過型フォトインタラプタ５ａと底板検知フィラー５ｂで構成された底板検知手段５が設けられており、自重にて垂れ下がっている底板検知フィラー５ｂは底板１が所定の高さに達したときその先端が底板の端部１ｃに当接するよう構成されている。
【００１７】
底板１の先端部では用紙積載量の違いにより底板１の高さの違いが顕著であるが、底板１の中央部は先端に比べ支点１ａに近いため底板１の高さの変化が少ない反面、用紙上面高さの違いが顕著となる（図３参照）。本図示例ではこの事に着目し底板検知手段５を底板１の先端側、用紙検知手段４をより支点１ａに近い側に配している。これによりそれぞれの検知精度が向上し正確な用紙残量検知手段が構成できる。
【００１８】
用紙検知フィラー４ｂにはフォトインタラプタ４ａを遮光する遮光板４ｃがあり、フィラー先端の載った用紙が満載時のおよそ２／３以下から１枚だけの時には遮光する状態に、用紙が無く用紙検知フィラー４ｂが底板１の穴部１ｂに落ち込んだ時と、用紙積載高さが満載時のおよそ２／３より多い時は遮光しない状態になるよう構成されている。
【００１９】
底板検知フィラー５ｂにもフォトインタラプタ５ａを遮光する遮光板５ｃがある。用紙残量がおよそ１／３以上の時は底板１が低い位置にあるため、底板検知フィラー５ｂは自重で垂れ下がった状態か、底板１の端部１ｃに当接しても遮光板５ｃがフォトインタラプタ５ａを遮光する状態となるよう構成されている。用紙残量がおよそ１／３未満の時は底板１の端部１ｃで底板検知フィラー５ｂの先端が持ち上げられて遮光しない状態となるよう構成されている。このため、用紙検知手段４及び底板検知手段５による信号の組み合わせにより表１のようになり、用紙無しを含めて４段階の用紙残量の検知が可能となる。なお、透過型フォトインタラプタ４ａ、５ａが遮光されない状態をＯＮ、遮光された状態をＯＦＦとしている。
【００２０】
【表１】

【００２１】
更にまた、用紙検知フィラー４ｂの近傍にはスプリング６ａとレバー部６ｂからなるフィラー待避手段６が設けられている。レバー部６ｂの先端には傾斜面６ｃが設けられ、用紙検知フィラー４ｂの側面より突出した突起部４ｄを下から掬う位置に構成されている。他端には下方に伸びた受面６ｄがあり給紙トレイ１００の背面１００ａに当接する。スプリング６ａはレバー部６ｂを給紙トレイ引き抜き方向に付勢しており、その時、用紙検知フィラー４ｂを持ち上げている。給紙トレイ１００が挿入されたときはトレイ背面１００ａによって受面６ｄが押されるので、先端傾斜面６ｃが後退し用紙検知フィラー４ｂは自重にて垂れ下がった状態となる（図４参照）。
【００２２】
用紙検知フィラー４ｂが底板１の中央ないし回転支点１ａに近い位置に有る場合、用紙検知フィラー４ｂが給紙トレイ１００の深い位置にまで垂れ下がるように構成されているため、そのまま給紙トレイ１００を挿抜すると用紙ガイドや給紙トレイの奥壁と用紙検知フィラー４ｂが干渉し、当該用紙検知フィラー４ｂを破損してしまうことがある。しかし、上記のような構成によって給紙トレイ１００の挿抜にあわせて用紙検知フィラー４ｂが自動的に待避状態と使用可能な状態とに変移するので用紙検知フィラー４ｂの破損を招くようなことがない。サイドガイドやトレイの奥壁を大きく切り欠くことも可能であるが、トレイやガイドの強度低下を招くため望ましくない。
【００２３】
本実施の形態例では底板が斜めに上がる傾斜タイプの給紙トレイについて述べたが、請求項１に関してはこれに限らず、底板を水平に持ち上げるタイプのトレイでも適用することができる。また用紙搬送方向と給紙トレイ１００の挿抜方向が直行式でない場合でも、請求項１または２に対しては適用することができる。
【００２４】
なお、本発明の画像形成装置は、上述の図示例にのみ限定されるものではなく、本発明の要旨を逸脱しない範囲内において種々変更を加え得ることは勿論である。
【００２５】
【発明の効果】
以上、説明したように本発明の請求項１から３記載の画像形成装置によれば、用紙検出手段を最小用紙サイズの後端近傍位置で検出することで最終紙の検出を早くし、無駄な作像工程を行わないことでトナー消費や装置の劣化、電力消費を押さえることができ、傾斜型の底板を有する用紙積載手段に合わせ、更に底板検知手段との検知信号の組み合わせにより４段階の用紙残量状態の検知を可能とし、使用者に対しより詳細な状態を告知でき、使用勝手が良好となり、また更に、用紙搬送方向とトレイ挿抜方向が直行する構成の給紙装置を設けた場合には、用紙検出手段を構成するフィラーを待避する手段を設け、かつトレイの引き抜き時に用紙検出フィラーが待避することで、トレイの挿抜によるフィラーの破損や、フィラーを避けるためにトレイの壁肉を減じることによる強度の減少を防ぐことができる、等種々の優れた効果を奏し得る。
【図面の簡単な説明】
【図１】本発明の画像形成装置の実施の形態の一例を示す概略断面図である。
【図２】図１に示す画像形成装置の給紙トレイの近傍の状態を示す斜視図である。
【図３】図２に示す傾斜した底板の支点近傍と先端との高さ変位を示す略図である。
【図４】図２に示す用紙検知フィラーと待避レバーの動作を示す略図である。
【符号の説明】
１底板（用紙積載手段）
４用紙検知手段
４ａ透過型フォトインタラプタ（用紙検知手段）
４ｂ用紙検知フィラー（用紙検知手段）
４ｃ遮光板（用紙検知手段）
４ｄ突起部（用紙検知手段）
５底板検知手段
５ａフォトインタラプタ（底板検知手段）
５ａ透過型フォトインタラプタ（底板検知手段）
５ｂ底板検知フィラー（底板検知手段）
５ｃ遮光板（底板検知手段）
６フィラー待避手段
１００給紙トレイ（用紙積載手段）
１０１用紙
１０２給紙部（給紙手段）[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an image forming apparatus such as a printer, a FAX, or a complex machine thereof.
[0002]
[Prior art]
In recent image forming apparatuses, since downsizing of the apparatus and improvement in productivity are demanded, there are many cases in which a sheet conveyance distance from a sheet feeding position to a transfer position where an image is formed on a sheet is short. Normally, it is preferable to start image formation after confirming the presence or absence of paper in the paper stacking unit. However, in the case of such an image forming apparatus, in order to improve productivity, when performing continuous image printing. In many cases, the next image formation is started while transferring the previous sheet before confirming the presence or absence of the next sheet.
[0003]
Since the means for detecting the presence or absence of paper is provided near the exit of the paper stacking means, the presence or absence of the next paper cannot be confirmed while the rear end of the previous paper is in the paper stacking means. Must be done. If it is determined that there is no paper after the start of image formation, the image being formed cannot be printed. Therefore, the toner required for the image formation is completely wasted, and it remains in the image forming section. Since a process for cleaning the untransferred toner occurs, it causes deterioration due to unnecessary consumption of life parts such as a photoconductor, and extra power consumption required for the process.
[0004]
[Problems to be solved by the invention]
In the present invention, in view of the above-mentioned problems of the prior art, the paper detection means detects the position near the rear end of the minimum paper size, thereby speeding up the detection of the final paper and eliminating unnecessary image forming processes. It is a first object of the present invention to provide an image forming apparatus that suppresses deterioration and power consumption of the apparatus.
[0005]
The present invention also provides an image forming apparatus capable of detecting the remaining state of the paper in four stages by combining with a paper stacking means having an inclined bottom plate and further combining a detection signal with the bottom plate detection means. Second purpose.
[0006]
Furthermore, in the present invention, in the paper feeding means configured so that the paper conveyance direction and the tray insertion / extraction direction are orthogonal, a means for retracting the paper detection filler constituting the paper detection means is provided, and the paper detection filler is provided when the tray is pulled out. It is a first object of the present invention to provide an image forming apparatus capable of preventing damage to the sheet detection filler due to insertion / extraction of the tray and reduction in strength due to reduction of the wall thickness of the tray in order to avoid the sheet detection filler. Three purposes.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, a first aspect of the present invention is a sheet stacking unit for stacking sheets, a sheet feeding unit for separating the sheets one by one and sending them to an image forming unit, and a sheet to the sheet feeding unit. In the image forming apparatus, comprising: a sheet support unit that is brought into contact with or controlled to be raised to a predetermined position; and a sheet detection unit that detects the presence or absence of a sheet in the sheet stacking unit, the sheet detection unit is stacked on the sheet stacking unit. An image forming apparatus that is configured to detect the vicinity of the trailing edge of the smallest sized paper among the possible paper sizes is the main feature.
[0008]
According to a second aspect of the present invention, the paper support means includes a bottom plate that supports the paper obliquely about a predetermined axis, and a bottom plate detection means that detects that the tip of the bottom plate is at a predetermined height. The detection unit is characterized by an image forming apparatus configured to generate the same signal when the sheet is above a predetermined height and when the sheet is not present.
[0009]
According to a third aspect of the present invention, the paper stacking means is provided so as to be insertable / removable in a direction perpendicular to the paper transport direction from the apparatus main body, and the paper support means includes a bottom plate that supports the paper obliquely about a predetermined axis. The paper detection means includes a filler that contacts the top surface of the paper, the bottom plate has a hole shape into which the filler falls, and when the paper stacking means is pulled out from the apparatus main body, the filler is retracted to a non-functional state, The image forming apparatus is provided with a retracting unit that sets the filler in a functional state when the stacking unit is set at a sheet feeding position.
[0010]
According to the present invention, the paper detection means detects the position near the rear end of the minimum paper size, thereby accelerating the detection of the final paper. By not performing a wasteful image forming process, toner consumption, device deterioration, and power consumption In addition to the paper stacking means with an inclined bottom plate, it is possible to detect the remaining state of the paper in 4 stages by combining the detection signal with the bottom plate detection means, and more detailed state for the user In the case where a sheet feeding device having a configuration in which the sheet conveyance direction and the tray insertion / removal direction are orthogonal to each other is provided, a means for retracting the filler constituting the sheet detection means is provided, and By retracting the paper detection filler when pulling out the tray, it is possible to prevent damage to the filler due to insertion and removal of the tray, and reduction in strength due to reduction of the wall thickness of the tray to avoid filler. Kill.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described together with illustrated examples. FIG. 1 is a schematic sectional view of an image forming apparatus of the present invention. The sheets 101 stacked on the sheet feeding tray 100 are separated one by one by the sheet feeding unit 102 and conveyed to the transfer unit 104 of the image forming unit 103. The sheet on which the image is transferred to the front surface by the transfer unit 104 is conveyed to the fixing unit 105, and after the image is fixed, the sheet discharging unit 106 discharges the sheet to the outside. On the other hand, in the image formation, the writing unit 107 in the image forming unit 103 forms a latent image on the photoconductor 108, the developing unit 109 attaches toner to the latent image, and the transfer unit 104 joins the sheet.
[0012]
The paper feed tray 100 is configured to be insertable / removable with respect to the apparatus main body, and is inserted / removed in a direction perpendicular to the conveyance direction of the paper 101. A bottom plate 1 is provided in the paper feed tray 100 and is supported so as to be rotatable about a fulcrum 1a. A spring 2 is provided on the lower side of the bottom plate 1 to bring the paper 101 into contact with the paper feed roller 3 with a predetermined pressure.
[0013]
Further, a sheet detection means 4 composed of a transmissive photo interrupter 4a and a sheet detection filler 4b is provided above the vicinity of the center of the bottom plate 1, and the leading end of the sheet detection filler 4b is a hole 1b provided in the bottom plate 1. It is configured to be depressed by its own weight. The hole 1b of the bottom plate 1 is located in the vicinity of the rear end of the smallest paper size (the minimum size here is the shortest size in the transport direction) of the paper sizes that can be stacked on the paper feed tray 100. When the paper 101 is on the top, the front end of the paper detection filler 4b comes into contact with the upper surface of the paper.
[0014]
In the case of the image forming apparatus as shown in FIG. 1, the length from the transfer unit 104 to the paper feed unit 102 is L1, the length from the paper feed unit 102 to the paper detection position is L2, and similarly, the transfer unit 104 is the starting point. When the length in the circumferential direction of the photosensitive member 108 up to the writing unit 107 that is the image formation start point is L3, the next (L1 + L2)> L3 must be satisfied before the presence or absence of the sheet can be confirmed. You will have to start image creation.
[0015]
In order to avoid the waste of image formation as described above, an interval time until the next image formation is provided and the image formation is started after the presence or absence of paper is detected. Therefore, the printing productivity is remarkably deteriorated. Therefore, in the illustrated example, the sheet is detected in the vicinity of the trailing edge of the minimum size sheet by increasing L2 as much as possible.
[0016]
Further, as shown in FIG. 2, a bottom plate detection means 5 comprising a transmissive photo interrupter 5a and a bottom plate detection filler 5b is provided above the bottom end of the bottom plate 1, and the bottom plate detection filler hanging down by its own weight. 5b is configured such that when the bottom plate 1 reaches a predetermined height, its tip abuts against the end 1c of the bottom plate.
[0017]
The difference in the height of the bottom plate 1 due to the difference in the amount of paper loaded is remarkable at the front end portion of the bottom plate 1, but since the center portion of the bottom plate 1 is closer to the fulcrum 1a than the front end, the change in the height of the bottom plate 1 is small. The difference in the upper surface height of the paper becomes noticeable (see FIG. 3). In the illustrated example, paying attention to this, the bottom plate detecting means 5 is arranged on the front end side of the bottom plate 1 and the paper detecting means 4 is arranged on the side closer to the fulcrum 1a. As a result, each detection accuracy is improved, and an accurate remaining paper amount detection unit can be configured.
[0018]
The paper detection filler 4b has a light shielding plate 4c that shields the photointerrupter 4a. When there is only one sheet having a filler on the front end, the paper detection filler is in a state of shielding light when there is only one sheet. When 4b falls into the hole 1b of the bottom plate 1 and when the sheet stacking height is more than about 2/3 of the full load, the light is not shielded.
[0019]
The bottom plate detection filler 5b also has a light shielding plate 5c that shields the photo interrupter 5a. When the remaining amount of paper is approximately 1/3 or more, the bottom plate 1 is in a low position. Therefore, even if the bottom plate detection filler 5b hangs down by its own weight or comes into contact with the end 1c of the bottom plate 1, the light shielding plate 5c remains in the photo interrupter. 5a is shielded from light. When the remaining amount of paper is less than about 1/3, the end of the bottom plate detection filler 5b is lifted by the end portion 1c of the bottom plate 1 so as not to block light. For this reason, the combinations of signals from the paper detection means 4 and the bottom plate detection means 5 are as shown in Table 1, and it is possible to detect the remaining amount of paper in four stages including no paper. The state where the transmissive photo interrupters 4a and 5a are not shielded is ON, and the shielded state is OFF.
[0020]
[Table 1]

[0021]
Furthermore, a filler retracting means 6 comprising a spring 6a and a lever portion 6b is provided in the vicinity of the paper detection filler 4b. An inclined surface 6c is provided at the tip of the lever portion 6b, and is configured at a position where the protrusion 4d protruding from the side surface of the paper detection filler 4b is crawled from below. The other end has a receiving surface 6 d that extends downward, and abuts against the back surface 100 a of the paper feed tray 100. The spring 6a urges the lever portion 6b in the direction of pulling out the paper feed tray, and at that time, the paper detection filler 4b is lifted. When the paper feed tray 100 is inserted, the receiving surface 6d is pushed by the tray back surface 100a, so that the tip inclined surface 6c is retracted and the paper detection filler 4b is hung by its own weight (see FIG. 4).
[0022]
When the paper detection filler 4b is located at the center of the bottom plate 1 or at a position close to the rotation fulcrum 1a, the paper detection filler 4b is configured to hang down to a deep position of the paper feed tray 100. Then, the back wall of the paper guide or the paper feed tray may interfere with the paper detection filler 4b, and the paper detection filler 4b may be damaged. However, since the sheet detection filler 4b is automatically changed between the retracted state and the usable state in accordance with the insertion / extraction of the paper feed tray 100 by the above configuration, the sheet detection filler 4b is not damaged. . Although it is possible to cut out the back wall of the side guide or the tray greatly, it is not desirable because it causes a decrease in strength of the tray or the guide.
[0023]
In the present embodiment, an inclined type paper feed tray in which the bottom plate rises diagonally has been described. However, the present invention is not limited to this, and can be applied to a tray that lifts the bottom plate horizontally. Further, even when the paper conveyance direction and the insertion / extraction direction of the paper feed tray 100 are not orthogonal, the present invention can be applied to the first or second aspect.
[0024]
Note that the image forming apparatus of the present invention is not limited to the above-described illustrated examples, and various modifications can be made without departing from the scope of the present invention.
[0025]
【The invention's effect】
As described above, according to the image forming apparatus of the first to third aspects of the present invention, the detection of the final sheet is accelerated by detecting the sheet detecting unit in the vicinity of the rear end of the minimum sheet size, which is useless. By not performing the image forming process, toner consumption, deterioration of the apparatus, and power consumption can be suppressed. In addition to the paper stacking means having an inclined bottom plate, four stages of paper are combined by combining detection signals with the bottom plate detection means. When it is possible to detect the remaining amount, notify the user of more detailed status, improve usability, and provide a paper feeding device with a configuration in which the paper transport direction and tray insertion / removal direction are orthogonal In order to avoid damage to the filler due to the insertion and removal of the tray and to prevent the filler by providing a means for retracting the filler constituting the paper detection means and by retracting the paper detection filler when the tray is pulled out Decrease in strength due to reduce the wall meat trays can be prevented, can achieve equal various excellent effects.
[Brief description of the drawings]
FIG. 1 is a schematic cross-sectional view showing an example of an embodiment of an image forming apparatus of the present invention.
2 is a perspective view showing a state in the vicinity of a paper feed tray of the image forming apparatus shown in FIG.
FIG. 3 is a schematic diagram showing the height displacement between the vicinity of the fulcrum and the tip of the inclined bottom plate shown in FIG. 2;
4 is a schematic diagram showing operations of a sheet detection filler and a retracting lever shown in FIG.
[Explanation of symbols]
1 Bottom plate (paper stacking means)
4 Paper detection means 4a Transmission type photo interrupter (paper detection means)
4b Paper detection filler (paper detection means)
4c Shading plate (paper detection means)
4d protrusion (paper detection means)
5 Bottom plate detection means 5a Photo interrupter (bottom plate detection means)
5a Transmission type photo interrupter (bottom plate detection means)
5b Bottom plate detection filler (bottom plate detection means)
5c Shading plate (bottom plate detection means)
6 Filler retracting means 100 Paper feed tray (paper stacking means)
101 Paper 102 Paper feed unit (paper feed means)

Claims

A paper stacking means for stacking paper, a paper feed means for separating the paper one by one and sending it to the image forming unit, and a paper support means for controlling the paper to come into contact with the paper feed means or to be raised to a predetermined position An image forming apparatus comprising: a sheet detecting unit configured to detect the presence or absence of a sheet in the sheet stacking unit; and the sheet detecting unit includes a trailing end of a minimum size sheet among the sheet sizes that can be stacked on the sheet stacking unit. An image forming apparatus configured to detect a vicinity.

2. The image forming apparatus according to claim 1, wherein the paper support means includes a bottom plate that supports the paper obliquely about a predetermined axis and a bottom plate detection means that detects that the tip of the bottom plate is at a predetermined height. The sheet detecting means is configured to generate the same signal when the sheet is above a predetermined height and when the sheet is not present.

2. The image forming apparatus according to claim 1, wherein the paper stacking means is provided so as to be able to be inserted and removed from the apparatus main body in a direction perpendicular to the paper transport direction, and the paper support means has a bottom plate that supports the paper obliquely about a predetermined axis. The sheet detecting means includes a filler that abuts against the upper surface of the sheet, the bottom plate has a hole shape into which the filler falls, and the filler is retracted to a non-functional state when the sheet stacking means is pulled out from the apparatus main body. An image forming apparatus provided with a retracting means for setting the filler in a functional state when the paper stacking means is set at the paper feeding position.