JP4279752B2 - Sheet-like medium detection device and image forming apparatus - Google Patents

Sheet-like medium detection device and image forming apparatus Download PDF

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JP4279752B2
JP4279752B2 JP2004250353A JP2004250353A JP4279752B2 JP 4279752 B2 JP4279752 B2 JP 4279752B2 JP 2004250353 A JP2004250353 A JP 2004250353A JP 2004250353 A JP2004250353 A JP 2004250353A JP 4279752 B2 JP4279752 B2 JP 4279752B2
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尚明 萩原
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Ricoh Co Ltd
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Description

本発明は、シート状媒体の搬送経路に配置されるシート状媒体検知装置及び該シート状媒体検知装置を備えたプリンタ、コピー機、ファクシミリ、印刷機、ＡＴＭ（Automatic Teller Machine）その他の画像形成装置に関する。   The present invention relates to a sheet-like medium detection device arranged in a sheet-like medium conveyance path, and a printer, a copier, a facsimile, a printing machine, an ATM (Automatic Teller Machine), and other image forming apparatuses provided with the sheet-like medium detection device. About.

シート状媒体の検知手段として、発光部及び受光部を一対で有する透過型検知手段とシート材の搬送に伴い回動することで該透過型検知手段の信号を遮蔽する遮蔽手段とを有した検知方式がある（例えば、特許文献１参照）。遮蔽手段として回動により信号遮蔽状態の切り替えを行なう方式を採用した場合、回動中心軸と、少なくとも、この回動中心軸から該遮蔽手段の回動半径分のスペースが必要となる。さらに、回動半径分のスペースを確保できたとして、該遮蔽手段の近傍にシート材搬送方向を切り替える分岐手段等、該遮蔽手段以外の回動を伴う手段が存在する場合においては両手段が干渉を起こさない充分な空間距離を確保する必要から装置の小型化に限界が生じる。   As a sheet medium detection unit, a detection unit includes a transmission type detection unit having a pair of a light emitting unit and a light receiving unit, and a shielding unit that shields a signal of the transmission type detection unit by rotating as the sheet material is conveyed. There is a method (for example, refer to Patent Document 1). When the method of switching the signal shielding state by rotation is adopted as the shielding means, a rotation center axis and at least a space corresponding to the rotation radius of the shielding means from the rotation center axis are required. Furthermore, assuming that a space corresponding to the turning radius can be secured, if there is a means with rotation other than the shielding means, such as a branching means for switching the sheet material conveying direction in the vicinity of the shielding means, both means interfere with each other. There is a limit to downsizing of the apparatus because it is necessary to secure a sufficient space distance without causing any problems.

特開平１１−０５９９６１号公報JP 11-059961 A

本発明は、シート材媒体検知装置の実装に際し、必要な空間を最小限にとどめ得る手段を提供することを課題とする。   It is an object of the present invention to provide means capable of minimizing a necessary space when mounting a sheet material medium detection device.

本発明は、前記課題を達成するため以下の構成とした。
シート状媒体の有無を検知するシート状媒体検知装置において、
シート状媒体を搬送する搬送手段と、
発光部及び受光部を一対で有する透過型検知手段と、
前記搬送手段によりシート状媒体が搬送される搬送経路と、
前記搬送経路に回動自在に設けられ該シート状媒体の搬送方向を切り換える分岐手段と、
前記分岐手段の回動中心軸と同一軸に支持されて回動自在であって、前記搬送経路に設けられ、その自由端部が前記発光部と前記受光部との間に位置して前記発光素子から出て前記受光部へ向かう光を途中で遮断する遮蔽状態となる回動位置と、該自由端部が前記発光部と前記受光部との間に位置しないことにより前記発光素子から出て前記受光部へ向かう光が遮断されることなく前記受光部に受光される非遮蔽状態となる回動位置、をとることができ、これら遮蔽状態となる回動位置と非遮蔽状態となる回動位置間の切り換えを、前記搬送路でのシート状媒体の搬送に伴って回動する遮蔽手段と、
前記遮蔽手段の自重による回転を該遮蔽手段が前記遮蔽状態となる回転位置で止めるストッパ機能部を有し、このストッパ機能部は当該シート状媒体検知装置の本体部からなり、
前記遮蔽手段は、前記遮蔽状態のもとで、前記搬送路を進むシート状媒体の先端部により押動されて該遮蔽状態から前記非遮蔽状態を経て、再び前記遮蔽状態に復帰する過程で、前記透過型検知手段の信号遮蔽状態を切り換えることとした（請求項１）。
ここで、分岐手段と遮蔽手段とは作動のタイミングが異なるので、それぞれが独自に作動することが可能なように、前記遮蔽手段は前記分岐手段の回動と独立して回動可能とした（請求項２）。そして、その方策の一つとして、前記遮蔽手段はその基端部が、自重による回転力で回転するように前記分岐手段の回動軸に嵌合している構成とした（請求項３）。
遮蔽手段の設置位置は、その機能上、搬送路上、定着装置と排紙ローラの間に配置する（請求項４）。遮蔽手段が設けられた搬送路の上方にも搬送路があり、この上方に設けられた搬送路にもシート状媒体の検知装置が設けられている場合、その検知装置は反射型検知装置を用いるのがよい（請求項５）。該上方の搬送路は両面印字用の反転路であり、前記分岐手段は、定着後のシート状媒体を前記反転路に送り出す進路と前記排紙ローラに送り出す進路とに切り換える構成の場合とする（請求項６）。これらの構成は、上下に２つの搬送路を有し、一方の搬送路から他方の搬送路にシート状媒体の進路を切り換える分岐手段を備えた両面画像形成可能な画像形成装置に適用することができる（請求項７）。 The present invention has the following configuration in order to achieve the above object.
In a sheet-like medium detection device that detects the presence or absence of a sheet-like medium,
Conveying means for conveying the sheet-like medium;
Transmissive detection means having a pair of light emitting part and light receiving part;
A transport path through which the sheet-like medium is transported by the transport means;
A branching means that is rotatably provided in the transport path and switches the transport direction of the sheet-like medium;
It is supported on the same axis as the rotation center axis of the branching means and is rotatable, and is provided in the transport path, and its free end is located between the light emitting part and the light receiving part, and the light emission. A rotating position where the light exits from the element and goes to the light receiving part is blocked in the middle, and the free end part is not located between the light emitting part and the light receiving part, and thus the light exits from the light emitting element. The rotation position where the light receiving portion is received by the light receiving portion without being blocked and the rotation position where the light receiving portion is not shielded can be taken. Shielding means for rotating the position according to the conveyance of the sheet medium in the conveyance path;
A stopper function unit that stops rotation of the shielding unit due to its own weight at a rotation position where the shielding unit is in the shielding state, and the stopper function unit includes a main body of the sheet-like medium detection device;
In the process of returning to the shielding state again from the shielding state through the non-shielding state, the shielding means is pushed by the leading end of the sheet-like medium traveling in the conveyance path under the shielding state. The signal shielding state of the transmission type detection means is switched ( Claim 1).
Here, since the branching means and the shielding means are operated at different timings, the shielding means can be turned independently of the turning of the branching means so that each of them can be operated independently ( Claim 2). And as one of the measures, the said shielding means was set as the structure fitted to the rotating shaft of the said branch means so that the base end part may rotate with the rotational force by dead weight (Claim 3).
The installation position of the shielding means is disposed between the fixing device and the paper discharge roller on the conveyance path in terms of its function. When there is also a transport path above the transport path provided with the shielding means, and a sheet-like medium detection device is also provided on the transport path provided above, a detection device is used as the detection device. (Claim 5). The upper conveyance path is a reversing path for double-sided printing, and the branching unit is configured to switch between a path for feeding the sheet-like medium after fixing to the reversing path and a path for feeding to the paper discharge roller ( Claim 6). These configurations can be applied to an image forming apparatus capable of double-sided image formation, which has two conveying paths at the top and bottom and includes a branching unit that switches the path of the sheet-like medium from one conveying path to the other. (Claim 7).

この発明では、搬送路に分岐手段と共に設置されるシート状媒体検知装置について、これら分岐手段およびシート状媒体検知装置について、回転中心軸の共有によりシート状媒体検知装置設置に伴うスペースの増大を回避することができる。 In the present invention, with respect to the sheet-like medium detection device installed together with the branching means on the conveyance path, an increase in space due to the installation of the sheet-like medium detection device is avoided by sharing the rotation center axis of the branching means and the sheet-like medium detection device. can do.

以下に、この発明の実施の形態を説明する。
（１）搬送路及び分岐手段
この発明に係るシート状媒体検知装置を備えた画像形成装置の外見を示した図１において、画像形成装置のケースにはシート状媒体が通る排紙口１、２として上下に２つの開口が形成されている。下の排紙口２から排出されるシート状媒体は排紙トレイ３上に積載される。上の排紙口１は片面の画像形成を終えたシート状媒体が、残る片面の画像形成のためにスイッチバックして画像形成部に戻る際に用いられる開口部であり、シート状媒体はこの排紙口１からその一部が外部に出るように送られたのち、再び画像形成装置内部に引き込まれる。 Embodiments of the present invention will be described below.
(1) Conveying path and branching unit In FIG. 1 showing the appearance of an image forming apparatus provided with a sheet-like medium detection device according to the present invention, paper discharge outlets 1 and 2 through which the sheet-like medium passes through the case of the image forming apparatus. As shown in FIG. The sheet-like medium discharged from the lower paper discharge port 2 is stacked on the paper discharge tray 3. The upper discharge port 1 is an opening used when a sheet-like medium on which one-sided image formation has been completed is switched back to return to the image forming unit for forming the remaining one-sided image. After a part of the paper is discharged from the paper discharge port 1, the paper is again drawn into the image forming apparatus.

図１に示した画像形成装置を同図１における斜左下から見たときの断面を示したのが図２であり、画像形成装置の主要な部材の構成を示している。図２において、排紙口２にはシート状媒体を排出搬送する搬送手段としての一対の排紙ローラ（以下、単にローラという。）４ａ、４ｂが配置されている。画像形成後のシート状媒体は、ローラ４ａ、４ｂの回転により矢印Ｂの向き（図３参照）に送り出されて排紙トレイ３上に積載される。 FIG. 2 shows a cross section of the image forming apparatus shown in FIG. 1 when viewed from the lower left of FIG. 1 , and shows the configuration of main members of the image forming apparatus. In FIG. 2, a pair of paper discharge rollers (hereinafter simply referred to as “rollers”) 4 a and 4 b are arranged at the paper discharge port 2 as conveying means for discharging and conveying the sheet-like medium. The sheet-like medium after the image formation is sent out in the direction of arrow B (see FIG. 3) by the rotation of the rollers 4a and 4b and stacked on the paper discharge tray 3.

図２に示した一対のローラ４ａ、４ｂ近傍部の断面を示した図３において、これら一対のローラ４ａ、４ｂのニップ部の近傍で、かつ、該ニップ部の左側下方の位置を起点として左下がりに傾斜した面からなる下ガイド傾斜面５ａがある。下ガイド傾斜面５ａは本体部８の上部に形成された傾斜面であり、左端部で略鉛直に落ち込み、下ガイド鉛直面５ｂとなっている。下ガイド傾斜面５ａのうち、ローラ４ｂ寄りの部位と対向する位置に略水平の上ガイド面６が位置している。 In FIG. 3 showing a cross section of the vicinity of the pair of rollers 4a and 4b shown in FIG. 2 , the left side of the nip portion in the vicinity of the nip portion of the pair of rollers 4a and 4b is the left starting point. There is a lower guide inclined surface 5a composed of a downwardly inclined surface. The lower guide inclined surface 5a is an inclined surface formed on the upper portion of the main body portion 8, and falls substantially vertically at the left end portion to form a lower guide vertical surface 5b. The substantially horizontal upper guide surface 6 is located at a position facing the portion near the roller 4b in the lower guide inclined surface 5a.

上ガイド面６は当該画像形成装置本体の一部である中間部７の下部に取り付けられた板状部材の下面からなる。中間部７は排出口１と排出口２の中間に位置してこれら排出口１と排出口２とを仕切る位置にある。中間部７にはローラ４ａが軸支されている。   The upper guide surface 6 includes a lower surface of a plate-like member attached to the lower portion of the intermediate portion 7 that is a part of the image forming apparatus main body. The intermediate portion 7 is located in the middle of the discharge port 1 and the discharge port 2 and is in a position for partitioning the discharge port 1 and the discharge port 2. A roller 4 a is pivotally supported on the intermediate portion 7.

図３において、下ガイド傾斜面５ａと対向する上方位置には下ガイド傾斜面５ａと略平行に傾斜したガイド面１２がある。ガイド面１２は、下ガイド傾斜面５ａと対向するだけでなく、さらに斜め下方に延びている。   In FIG. 3, there is a guide surface 12 that is inclined substantially parallel to the lower guide inclined surface 5a at an upper position facing the lower guide inclined surface 5a. The guide surface 12 not only opposes the lower guide inclined surface 5a but also extends obliquely downward.

下ガイド鉛直面５ｂに対向するガイド面１３ｂと、ガイド面１２に対向するガイド面１３ａとを具備した両ガイド部材１３がある。この両ガイド部材１３は斜め右上側に進むにつれてガイド面１３ａとガイド面１３ｂとが接近する形状をしているので、次第にこれらの間隔が狭くなり、図３に示すように先端部が鋭角状に尖っている。この鋭角状になっている部位を鋭角部１３ｃと称する。   There are both guide members 13 each having a guide surface 13 b facing the lower guide vertical surface 5 b and a guide surface 13 a facing the guide surface 12. Since both guide members 13 are shaped so that the guide surface 13a and the guide surface 13b approach each other as they go obliquely to the upper right, the distance between them gradually becomes narrower, and the tips become sharper as shown in FIG. Pointed. This portion having an acute angle is referred to as an acute angle portion 13c.

中間部７の上面７ａはガイド面１２と対向していてシート状媒体の通路を構成している。この通路内にニップ部が位置するようにして一対のローラ１４ａ、１４ｂが設けられている。ローラ１４ａはガイド面１２の上部であって、図示省略の本体部に軸支されている。ローラ１４ｂは中間部７に軸支されている。   The upper surface 7a of the intermediate portion 7 is opposed to the guide surface 12 and constitutes a sheet medium passage. A pair of rollers 14a and 14b are provided so that the nip portion is positioned in the passage. The roller 14a is an upper part of the guide surface 12 and is pivotally supported by a main body (not shown). The roller 14b is pivotally supported by the intermediate portion 7.

下ガイド鉛直面５ｂとガイド面１３ｂとの対向間はシート状媒体の通路を構成している。下ガイド鉛直面５ｂとガイド面１３ｂとの対向間から、上ガイド傾斜面５ａを経てさらに、一対のローラ４ａ、４ｂのニップ部を経て排紙口２を経由し矢印Ｂに至る破線で示す経路はシート状媒体の搬送路１５である。   A space between the lower guide vertical surface 5b and the guide surface 13b constitutes a sheet medium passage. A path indicated by a broken line from between the lower guide vertical surface 5b and the guide surface 13b through the upper guide inclined surface 5a, further through the nip portion of the pair of rollers 4a and 4b, to the arrow B through the paper discharge port 2. Is a conveyance path 15 for the sheet-like medium.

ガイド面１２とガイド面１３ａとの対向間から、中間部材７の上面７ａを経てさらに、一対のローラ１４ａ、１４ｂのニップ部を経て排紙口１を経由し、矢印Ｃに至る破線で示す経路はシート状媒体の反転搬送路１６である。   A path indicated by a broken line extending from the opposing face of the guide surface 12 and the guide surface 13a, through the upper surface 7a of the intermediate member 7, through the nip portion of the pair of rollers 14a and 14b, through the paper discharge port 1, and to the arrow C. Is the reverse conveyance path 16 of the sheet-like medium.

これら搬送路１５、反転搬送路１６におけるシート状媒体の搬送駆動力は、搬送路１５に設けられた一対のローラ４ａ、４ｂや、定着装置１９内部に配置された定着用の一対のローラ１９ａ、１９ｂ、反転搬送路１６に設けられた一対のローラ１４ａ、１４ｂ、その他の搬送ローラにより与えられる。これらのローラはシート状媒体を搬送するので、シート状媒体の搬送手段と称する。   The conveyance driving force of the sheet-like medium in the conveyance path 15 and the reverse conveyance path 16 includes a pair of rollers 4 a and 4 b provided in the conveyance path 15 and a pair of fixing rollers 19 a disposed inside the fixing device 19. 19b, a pair of rollers 14a and 14b provided in the reverse conveyance path 16 and other conveyance rollers. Since these rollers convey the sheet-like medium, they are referred to as sheet-like medium conveying means.

下ガイド傾斜面５ａの左右方向での中間位置から当該下ガイド傾斜面５ａより垂直に立ち上げた位置に軸１１がある。軸１１は対向する下ガイド傾斜面５ａとガイド面１２との中間に位置し、図３の紙面を貫く方向（搬送されるシート状媒体の幅方向）に長さを有する。   The shaft 11 is located at a position where the lower guide inclined surface 5a is vertically raised from the intermediate position in the left-right direction of the lower guide inclined surface 5a. The shaft 11 is located between the opposed lower guide inclined surface 5a and the guide surface 12, and has a length in a direction penetrating the paper surface of FIG. 3 (width direction of the sheet-like medium to be conveyed).

軸１１には分岐手段としての分岐爪１７が固定されていて、軸１１と共に回動する。軸１１及び分岐爪１７の立体的な形状を図４に示す。分岐爪１７は、軸１１の長手方向に間隔をおいて多数固定されている。分岐爪１７は鳥のくちばしのような形状をしている。つまり、図３において、斜め左下側の端部１７ａに進むにつれて湾曲し、先端部１７ａが尖った形状をしている。反対側の端部１７ｂは三角形の底辺のような幅を有している。   A branch claw 17 as a branch means is fixed to the shaft 11 and rotates together with the shaft 11. The three-dimensional shapes of the shaft 11 and the branching claw 17 are shown in FIG. Many branching claws 17 are fixed at intervals in the longitudinal direction of the shaft 11. The branch claw 17 has a shape like a bird's beak. That is, in FIG. 3, it curves as it goes to the diagonally lower left end 17a, and the tip 17a has a sharp shape. The opposite end 17b has a width similar to the base of a triangle.

軸１１は図示しない駆動手段に連結されていて、適時のタイミングで所定角度揺動させられる。所定角度とは、以下に説明するように、分岐爪１７がシート状媒体を排紙トレイ３へ送り出すときの排紙状態の位置とシート状媒体を画像形成装置内部へ戻す反転搬送の位置をとり得る角度である。   The shaft 11 is connected to driving means (not shown), and is swung by a predetermined angle at an appropriate timing. As described below, the predetermined angle refers to the position of the paper discharge state when the branching claw 17 sends the sheet medium to the paper discharge tray 3 and the position of the reverse conveyance for returning the sheet medium to the inside of the image forming apparatus. The angle to get.

図１、図３に実線で示した分岐爪１７の位置が排紙状態の位置であり、図２に破線で示した位置が反転搬送状態であり、軸１１の回動により分岐爪１７はこれらの２つの状態位置に切り換えられる。このように、搬送経路に回動自在に設けられた分岐爪１７はシート状媒体の搬送方向を切り換える機能を有する。   The position of the branching claw 17 shown by the solid line in FIGS. 1 and 3 is the discharge state, and the position shown by the broken line in FIG. 2 is the reverse conveyance state. The two state positions are switched. As described above, the branching claw 17 rotatably provided in the conveyance path has a function of switching the conveyance direction of the sheet-like medium.

排紙状態では、分岐爪１７の先端部１７ａが両ガイド部材１３と交差する状態となり、かつ、後端部１７ｂも中間部７と交差した状態となっている。これにより、両ガイド部材１３と中間部７との間の間隔は完全に塞がれ、搬送路１５を上向きに搬送されてくるシート状媒体は分岐爪の下面により進路を下ガイド傾斜面１５ａに沿う方向に変えられて搬送路１５に沿って送られ、矢印Ｂの向きに排出されて排紙トレイ３上に積載される。   In the paper discharge state, the leading end portion 17 a of the branching claw 17 intersects with both guide members 13, and the rear end portion 17 b also intersects with the intermediate portion 7. As a result, the gap between the guide members 13 and the intermediate portion 7 is completely closed, and the sheet-like medium conveyed upward in the conveyance path 15 is routed to the lower guide inclined surface 15a by the lower surface of the branching claw. The direction is changed along the transport path 15, discharged in the direction of arrow B, and stacked on the discharge tray 3.

反転搬送状態では、図２に２点鎖線で示すように先端部１７ａが本体部８と交差して完全に本体部の内側まで入り込むまで回動する。これにより、分岐爪１７の上面部が下ガイド鉛直面５ｂの延長上に位置してつなぎ搬送路１８（図３参照）を形成して搬送路１５を反転搬送路１６につなぐとともに、下ガイド傾斜面１５ａに至る搬送路１５を塞ぐ状態となり、シート状媒体の進路は途中から搬送路１５より搬送路１６に切り換えられてローラ１４ａ、１４ｂのニップ部へ向かう。 In the reverse conveyance state, as shown by a two-dot chain line in FIG. 2, the distal end portion 17a rotates until it intersects the main body portion 8 and completely enters the inside of the main body portion. Thus, the connecting the connecting transport path 18 (see FIG. 3) reversing transport path 16 to the transport path 15 formed by the upper surface portion is positioned on an extension of the lower guide vertical plane 5 b of the branch claw 17, the lower guide The conveyance path 15 reaching the inclined surface 15a is closed, and the path of the sheet-like medium is switched from the conveyance path 15 to the conveyance path 16 from the middle to the nip portion of the rollers 14a and 14b.

やがて、シート状媒体は、ローラ１４ａ、１４ｂのニップ部にその先端部をくわえ込まれ、その後端部がローラ１４ａ、１４ｂのニップ部を通過する前に、これらローラの回転方向がシート状媒体を戻す向き（図３で斜め左下へ向かう向き）に切り換えられる。これにより、シート状媒体は逆進するが、この逆進が行なわれる直前に分岐爪１７は図３に実線で示す位置に復帰させられるので、シート状媒体は分岐爪１７の上面をガイドにして左方に向けて送られる。このように適切なタイミングでローラ１４ａ、１４ｂを逆転させることでシート状媒体をスイッチバックさせて搬送することができる。   Eventually, the leading edge of the sheet-like medium is inserted into the nip portions of the rollers 14a and 14b, and before the trailing edge passes through the nip portion of the rollers 14a and 14b, the rotation direction of these rollers changes the sheet-like medium. The direction is switched back (the direction toward diagonally lower left in FIG. 3). As a result, the sheet-like medium moves backward, but the branching claw 17 is returned to the position indicated by the solid line in FIG. 3 immediately before the backward movement is performed, so that the sheet-like medium is guided by the upper surface of the branching claw 17. Sent to the left. Thus, by rotating the rollers 14a and 14b in reverse at an appropriate timing, the sheet-like medium can be switched back and conveyed.

このように、分岐爪１７は搬送経路に回動自在に設けられシート状媒体の搬送方向を切り換える機能を有している。   As described above, the branching claw 17 is provided rotatably on the transport path and has a function of switching the transport direction of the sheet-like medium.

（２）遮蔽手段
図３において、本体部８は中空であり、その右端から中央にかけてスリット９が形成されていて、このスリット９にその自由端部が入り込むようにして遮蔽手段としての遮蔽部材１０が位置している。遮蔽部材１０は軸１１に取り付けられている。その取り付け位置は図４に示すように、シート状媒体の幅方向の中央位置である。 (2) Shielding means In FIG. 3, the main body 8 is hollow, and a slit 9 is formed from the right end to the center, and the free end part enters the slit 9 and the shielding member 10 as the shielding means 10. Is located. The shielding member 10 is attached to the shaft 11. The attachment position is the center position in the width direction of the sheet-like medium, as shown in FIG.

遮蔽部材１０は樹脂製で板状をしており、その基端部１０ａは図５に示すようにＣ字形をしていて、このＣ字状の開口部を軸１１に当てて押し込むことで弾性により軸１１に押し広げられ、開口部が最大半径部を過ぎるとその形状が原状に復し、該軸１１に対して回動自在に嵌合するようになる。このように、遮蔽部材１０は分岐爪１７の回動中心軸である軸１１を中心に回動自由である。   The shielding member 10 is made of resin and has a plate shape, and its base end portion 10a has a C shape as shown in FIG. 5, and the C-shaped opening portion is pressed against the shaft 11 to be elastic. When the opening portion passes through the maximum radius portion, the shape is restored to the original shape, and the shaft 11 is rotatably fitted to the shaft 11. Thus, the shielding member 10 is freely rotatable around the axis 11 that is the rotation center axis of the branch claw 17.

遮蔽部材１０はその形状が基端部１０ａから自由端部１０ｃに向かうにつれて基端部１０ａよりも幅が広がっていて、かつ、中間位置には自重による回転力を強化するため錘１０ｂが取り付けてある。   The shielding member 10 is wider in width than the base end portion 10a as the shape thereof moves from the base end portion 10a to the free end portion 10c, and a weight 10b is attached to the intermediate position to strengthen the rotational force due to its own weight. is there.

遮蔽部材１０は自重による回転力でその自由端部１０ｃが軸１１の真下に位置して安定しようとする習性がある。この真下に安定する少し手前の位置でスリット９の端部のストッパ機能により遮蔽部材１０の回動は阻止されるようになっている。つまり、自重による回転力で上記ストッパ機能部に押し当てられることで、図３に示すように、遮蔽部材１０の側面１０ｄは鉛直に対して傾いた状態で安定保持される。   The shielding member 10 has a habit of attempting to stabilize the free end portion 10c positioned immediately below the shaft 11 by a rotational force due to its own weight. The rotation of the shielding member 10 is prevented by a stopper function at the end of the slit 9 at a position just before this that is stabilized just below. That is, as shown in FIG. 3, the side surface 10d of the shielding member 10 is stably held in a state of being inclined with respect to the vertical by being pressed against the stopper function portion by the rotational force due to its own weight.

その安定保持される位置は、側面１０ｄが搬送路１５を塞ぐ位置であり、このとき側面１０ｄは搬送路１５と略直交する関係にある。この略直交する関係位置により、搬送路１５を搬送されるシート状媒体の先端の力が最も効率よく遮蔽部材１０の側面１０ｄに作用するようになる。かつ、真下に安定する少し手前の位置で回動を阻止されているので、側面１０ｄを押す力により敏感に遮蔽部材１０が回動することとなる。   The position where the side surface 10d is stably held is a position where the side surface 10d closes the conveyance path 15, and at this time, the side surface 10d is in a relationship substantially orthogonal to the conveyance path 15. Due to the substantially orthogonal relational position, the force at the tip of the sheet-like medium conveyed through the conveyance path 15 is most efficiently applied to the side surface 10d of the shielding member 10. In addition, since the rotation is prevented at a position just before it is stabilized immediately below, the shielding member 10 is sensitively rotated by the force of pressing the side surface 10d.

図３に示したように、遮蔽部材１０がスリット９の端部で係止されたときの状態を部材の要部を抜き出して図６、図８に示す。これらの図に示すように、遮蔽部材１０の自由端部１０ｃの近傍部を間に挟むようにして透過型検知手段としての発光部をもつ発光素子２０ａと受光部をもつ受光素子２０ｂが不動に配置されている。発光素子２０ａから出た光は遮蔽部材１０により遮断されて受光素子２０ｂに届かない状態にある。   As shown in FIG. 3, the state when the shielding member 10 is locked at the end of the slit 9 is shown in FIGS. As shown in these drawings, a light emitting element 20a having a light emitting part as a transmission type detecting means and a light receiving element 20b having a light receiving part are fixedly arranged so as to sandwich the vicinity of the free end part 10c of the shielding member 10. ing. The light emitted from the light emitting element 20a is blocked by the shielding member 10 and does not reach the light receiving element 20b.

分岐爪１７が図２に示す実線で示す位置にあるとき、図３に示すように分岐爪１７は下ガイド傾斜面５ａの上方を覆い、搬送路１５を完全な状態にしている。この状態のもとで、搬送路１５をたどって搬送されてきたシート状媒体はその先端部が遮蔽部材１０の側面１０ｄに当接し、さらに、遮蔽部材の自重による回転力に勝る搬送力によって遮蔽部材１０を押し動かして進む。これに伴い、遮蔽部材１０は軸１１を回動中心として回転して、その自由端部１０ｃが図９に破線で示すような形で搬送されるシート状媒体により押し上げられるので、発光素子２０ａと受光素子２０ｂとの間には遮蔽部材がなくなり、図７に示すように受光素子２０ｂは発光素子２０ａの光を受光する。   When the branching claw 17 is at the position indicated by the solid line shown in FIG. 2, the branching claw 17 covers the upper side of the lower guide inclined surface 5a as shown in FIG. In this state, the sheet-like medium conveyed along the conveyance path 15 has its front end in contact with the side surface 10d of the shielding member 10, and is further shielded by a conveyance force that exceeds the rotational force due to the weight of the shielding member. The member 10 is pushed and moved. Accordingly, the shielding member 10 rotates about the shaft 11 and the free end portion 10c thereof is pushed up by the sheet-like medium conveyed in the form shown by the broken line in FIG. There is no shielding member between the light receiving element 20b and the light receiving element 20b receives light from the light emitting element 20a as shown in FIG.

このように、受光素子２０による受光の有無から、受光素子２０の部位におけるシート状媒体の有無を検出することができる。シート状媒体の後端部が遮蔽部材１０から外れると、遮蔽部材１０は自重により回動して、初期状態つまり、図３、図６、図８に示すような遮蔽状態に自動復帰する。   Thus, the presence or absence of the sheet-like medium at the site of the light receiving element 20 can be detected from the presence or absence of light reception by the light receiving element 20. When the rear end portion of the sheet-like medium is detached from the shielding member 10, the shielding member 10 is rotated by its own weight, and automatically returns to the initial state, that is, the shielding state as shown in FIGS.

このように遮蔽部材１０は、搬送経路に回動自在に設けられシート状媒体の搬送に伴い回動することで透過型検知手段の信号遮蔽状態を切り換える機能を有する。
（３）画像形成装置
前記した分岐手段や遮蔽手段を備えた画像形成装置の一例としてシート状媒体の両面に画像形成可能なカラー画像形成装置について、主な構成及び画像を得る過程を説明する。図２において、装置本体１００の内部には、中間転写ベルト１１０を有する転写ベルト装置１１１と４つのプロセスカートリッジ９０Ｙ、９０Ｃ、９０Ｍ、９０ＢＫが配置されている。 As described above, the shielding member 10 is provided on the conveyance path so as to be rotatable, and has a function of switching the signal shielding state of the transmission type detecting means by rotating with the conveyance of the sheet-like medium.
(3) Image Forming Apparatus A color image forming apparatus capable of forming an image on both sides of a sheet-like medium as an example of an image forming apparatus provided with the above-described branching unit and shielding unit will be described with reference to a main configuration and a process for obtaining an image. In FIG. 2, a transfer belt device 111 having an intermediate transfer belt 110 and four process cartridges 90Y, 90C, 90M and 90BK are arranged inside the apparatus main body 100.

各プロセスカートリッジ９０Ｙ、９０Ｃ、９０Ｍ、９０ＢＫは、例えばシアン用プロセスカートリッジ９０Ｃについては、現像装置６０Ｃ、クリーニング装置８３Ｃ、感光体ドラム８０Ｃ、帯電装置８５Ｃ、を一体化したユニットになっている。他の色のプロセスカートリッジ９０Ｙ、９０Ｍ、９０ＢＫについてもこれに準じた構成となっている。   Each process cartridge 90Y, 90C, 90M, 90BK is a unit in which, for example, for the cyan process cartridge 90C, the developing device 60C, the cleaning device 83C, the photosensitive drum 80C, and the charging device 85C are integrated. The other color process cartridges 90Y, 90M, and 90BK have the same configuration.

詳細に説明すると、例えば、シアン用プロセスカートリッジ９０Ｃについて、現像装置６０Ｃは現像ケースに収められていて、この現像ケースとクリーニング装置８３Ｃが一体化されてユニットケースが構成され、ユニットケースに像担持体としての感光体ドラム８０Ｃが回転自在に支持されている。そして、クリーニング装置８３Ｃには専用の帯電装置８５Ｃが一体的に組み付けられている。各プロセスカートリッジ９０Ｙ、９０Ｃ、９０Ｍ、９０ＢＫは同じ大きさ、構成をしている。   More specifically, for example, for the cyan process cartridge 90C, the developing device 60C is housed in a developing case, and the developing case and the cleaning device 83C are integrated to form a unit case. A photosensitive drum 80C is supported rotatably. A dedicated charging device 85C is integrally assembled with the cleaning device 83C. Each process cartridge 90Y, 90C, 90M, 90BK has the same size and configuration.

画像形成装置本体１００の上部には、図中左からトナーを補給するトナーボトル９００Ｙ、９００Ｃ、９００Ｍ、９００Ｂｋが配置されており、これらのトナーボトルには順にイエロー（Ｙ）、シアン（Ｃ）、マゼンタ（Ｍ）、黒（Ｂｋ）のトナーが充填されており、ここから図示しない供給経路を経て所定の補給量だけ各色のトナーが現像装置６０Ｙ、６０Ｃ、６０Ｍ、６０Ｂｋに補給される。   In the upper part of the image forming apparatus main body 100, toner bottles 900Y, 900C, 900M, and 900Bk for replenishing toner are arranged from the left in the drawing, and these toner bottles are sequentially yellow (Y), cyan (C), Magenta (M) and black (Bk) toners are filled, and toner of each color is supplied to the developing devices 60Y, 60C, 60M, and 60Bk through a supply path (not shown) from here.

動作に関しては、給紙部２００よりシート状媒体が給紙ローラ３００によって送り出され、シート状媒体の先端部がレジストローラ対３４０まで到達するとこの到達が図示しないセンサによって検出される。この検出信号でタイミングを取りながら、レジストローラ対３４０によってシート状媒体は２次転写ローラ３５０と中間転写ベルト１１０とのニップ部に搬送される。   Regarding the operation, the sheet-like medium is sent out from the sheet feeding unit 200 by the sheet feeding roller 300, and when the leading end of the sheet-like medium reaches the registration roller pair 340, this arrival is detected by a sensor (not shown). While taking a timing with this detection signal, the sheet-like medium is conveyed to the nip portion between the secondary transfer roller 350 and the intermediate transfer belt 110 by the registration roller pair 340.

予め帯電装置８５Ｙ、８５Ｃ、８５Ｍ、８５Ｂｋによって一様に帯電された感光体ドラム８０Ｙ、８０Ｃ、８０Ｍ、８０Ｂｋは、光書込み装置１８０によりレーザー光にて露光走査され、感光体ドラム８０Ｙ、８０Ｃ、８０Ｍ、８０Ｂｋ上に静電潜像が作られる。   The photosensitive drums 80Y, 80C, 80M, and 80Bk, which are uniformly charged in advance by the charging devices 85Y, 85C, 85M, and 85Bk, are exposed and scanned with laser light by the optical writing device 180, and the photosensitive drums 80Y, 80C, and 80M are obtained. , An electrostatic latent image is created on 80 Bk.

各静電潜像は、それぞれ各色の現像装置６０Ｙ、６０Ｃ、６０Ｍ、６０Ｂｋにより現像され、感光体ドラム８０Ｙ、８０Ｃ、８０Ｍ、８０Ｂｋ表面にイエロー、シアン、マゼンタ、黒のトナー像が形成される。   The electrostatic latent images are developed by the developing devices 60Y, 60C, 60M, and 60Bk for the respective colors, and yellow, cyan, magenta, and black toner images are formed on the surfaces of the photosensitive drums 80Y, 80C, 80M, and 80Bk.

次に１次転写ローラ１２０Ｙ、１２０Ｃ、１２０Ｍ、１２０Ｂｋに電圧が印加され、感光体ドラム８０Ｙ、８０Ｃ、８０Ｍ、８０Ｂｋ上のトナーが、中間転写ベルト１１０上に順次転写されていく。この時各色の作像動作は、そのトナー像が中間転写ベルト１１０の同じ位置に重ねて転写されるように、中間転写ベルト１１０の回転方向での上流側から下流側に向けてタイミングをずらして実行される。   Next, a voltage is applied to the primary transfer rollers 120Y, 120C, 120M, and 120Bk, and the toner on the photosensitive drums 80Y, 80C, 80M, and 80Bk is sequentially transferred onto the intermediate transfer belt 110. At this time, the image forming operation of each color is shifted in timing from the upstream side to the downstream side in the rotation direction of the intermediate transfer belt 110 so that the toner image is transferred to the same position on the intermediate transfer belt 110. Executed.

中間転写ベルト１１０上に形成された重ねトナー画像は、２次転写ローラ３５０の位置まで搬送され、シート状媒体に２次転写される。各色のトナー像が転写されたシート状媒体は、定着装置１９に搬送されて熱定着される。   The superimposed toner image formed on the intermediate transfer belt 110 is conveyed to the position of the secondary transfer roller 350 and is secondarily transferred to a sheet-like medium. The sheet-like medium on which the toner image of each color is transferred is conveyed to the fixing device 19 and thermally fixed.

片面画像形成モードの場合には、定着後のシート状媒体は、予め図２に実線で示した位置に切り換えられた分岐爪１７により進路をローラ４ａ、４ｂのニップ部に向けられ、ローラ４ａ、４ｂにより排紙トレイ３に排出積載される。   In the case of the single-sided image forming mode, the sheet-like medium after fixing is directed to the nip portion of the rollers 4a and 4b by the branching claw 17 that has been previously switched to the position indicated by the solid line in FIG. The sheet is discharged and stacked on the sheet discharge tray 3 by 4b.

また、両面画像形成モードの場合には、定着後のシート状媒体は、予め図２に２点鎖線で示した位置に切り換えられた分岐爪１７により図３に示したつなぎ搬送路１８を通りローラ１４ａ、１４ｂのニップ部に向けられ、ローラ１４ａ、１４ｂにより送り出され、該シート状媒体の後端部がガイド面１３ｂを抜けた時点でローラ１４ａ、１４ｂがそれまでと逆転して、シート状媒体をスイッチバックさせこれまで後端側だった部位を先端側として搬送路１６を斜め下向きに搬送される。   In the case of the double-sided image forming mode, the sheet-like medium after fixing passes through the connecting conveyance path 18 shown in FIG. 3 by the branching claw 17 previously switched to the position shown by the two-dot chain line in FIG. 14a, 14b is directed to the nip portion of the sheet-like medium, and is fed by the rollers 14a, 14b. When the rear end of the sheet-like medium passes through the guide surface 13b, the rollers 14a, 14b are reversely rotated so far. Is switched back and the transport path 16 is transported obliquely downward with the portion that has been the rear end until now as the front end.

こうして、搬送されるシート状媒体は、図２に示す搬送コロ対３０、３１、３２を経てレジストローラ対３４０に至り、中間転写ベルト１１０上に形成された裏面用の画像とタイミングを合わせて送り出され、２次転写ローラ３５０を通過する間に裏面に画像が転写され、こうして両面に画像が形成されたシート状媒体は定着装置１９を通過することにより裏面の画像が定着され、ローラ１４ａ、１４ｂにより排紙トレイ３に送り出される。   Thus, the conveyed sheet-like medium reaches the registration roller pair 340 through the conveyance roller pairs 30, 31, and 32 shown in FIG. 2, and is sent out in time with the image for the back surface formed on the intermediate transfer belt 110. Then, the image is transferred to the back surface while passing through the secondary transfer roller 350, and thus the sheet-like medium on which the image is formed on both surfaces passes through the fixing device 19, whereby the image on the back surface is fixed, and the rollers 14a and 14b. Is sent out to the paper discharge tray 3.

なお、感光体ドラム８０Ｙ、８０Ｃ、８０Ｍ、８０Ｂｋ上の残留トナーは、それぞれのクリーニング装置８３Ｙ、８３Ｃ、８３Ｍ、８３Ｂｋでクリーニングされ、その後、直流に交流成分のバイアスが重畳印加された帯電用電圧を印加する帯電装置８５Ｙ、８５Ｃ、８５Ｍ、８５Ｂｋによって除電と同時に帯電され、次の作像に備える。また、中間転写ベルト１１０上の残留トナーは、中間転写ベルトクリーニング装置１３０によってクリーニングされ、次の作像工程に備えられる。   The residual toner on the photosensitive drums 80Y, 80C, 80M, and 80Bk is cleaned by the respective cleaning devices 83Y, 83C, 83M, and 83Bk, and then a charging voltage in which an AC component bias is applied to the DC is superimposed. The electrification devices 85Y, 85C, 85M, and 85Bk to be applied are charged simultaneously with static elimination to prepare for the next image formation. The residual toner on the intermediate transfer belt 110 is cleaned by the intermediate transfer belt cleaning device 130 and is prepared for the next image forming process.

ここで、透過型のセンサである発光素子２０ａと受光素子２０ｂ及び遮蔽部材１０などからなるシート状媒体検知装置によるシート状媒体有無の検知結果は、給紙部２００から次のシート状媒体を搬送させる給紙トリガとなり、また、ローラ４ａ、４ｂの下流側にフィニッシャー、ステープラー等の後処理装置を付帯する構成においては、これら後処理装置のスタートトリガとなる。   Here, the detection result of the presence or absence of the sheet-like medium by the sheet-like medium detection device including the light-emitting element 20a, the light-receiving element 20b, the shielding member 10, and the like, which are transmission type sensors, conveys the next sheet-like medium from the sheet feeding unit 200. In a configuration in which an aftertreatment device such as a finisher or a stapler is attached downstream of the rollers 4a and 4b, it becomes a start trigger for these aftertreatment devices.

一方、上記両面画像形成モードにおいて、ローラ１４ａ、１４ｂを逆転させるタイミングは、図３において分岐爪１７の上方であって、ガイド面１２に形成した開口に設けられた反射型のセンサ３３によりなされるようにしている。
（４）
前記したとおり、遮蔽部材１０の回動中心軸も分岐部材１７の回動中心軸も同一の軸１１としたので、回転中心軸の共有により遮蔽部材１０を設置する際、新たに専用の軸を設ける必要がなく、スペースの増大を回避することができる。但し、回転中心軸を共有するとはいっても、分岐部材１７と遮蔽部材１０とは機能が異なり、動作するタイミングも異なる。そこで、分岐部材１７については軸１１と一体的に回動するようにし、遮蔽部材については、シート状媒体が到来したときにはいつでも該シート状媒体により押動されるように自重による回転力で回転できるように軸１１に嵌合させた。これにより遮蔽部材は分岐部材とは独立して回動可能となり、シート状媒体の検知が可能である。 On the other hand, in the double-sided image forming mode, the timing of reversing the rollers 14a and 14b is made by the reflective sensor 33 provided above the branching claw 17 and in the opening formed in the guide surface 12 in FIG. I am doing so.
(4)
As described above, since the rotation center axis of the shielding member 10 and the rotation center axis of the branch member 17 are the same axis 11, when the shielding member 10 is installed by sharing the rotation center axis, a new dedicated axis is provided. There is no need to provide it, and an increase in space can be avoided. However, although the rotation center axis is shared, the branching member 17 and the shielding member 10 have different functions and different operating timings. Therefore, the branch member 17 is rotated integrally with the shaft 11, and the shielding member can be rotated by the rotational force of its own weight so that the sheet-like medium is pushed whenever the sheet-like medium arrives. Thus, the shaft 11 was fitted. Accordingly, the shielding member can be rotated independently of the branch member, and the sheet-like medium can be detected.

遮蔽部材１０は搬送路上、定着装置１９とローラ４ａ、４ｂの間に配置したが、この位置が定着という画像形成の最終処理を終えていて、かつ、搬送路の終端に近いので、ジャムの検知を兼ね前記した給紙トリガや後処理装置のスタートトリガとするのに適切だからである。   Although the shielding member 10 is disposed between the fixing device 19 and the rollers 4a and 4b on the conveyance path, this position has finished the final image forming process of fixing and is close to the end of the conveyance path, so that jam detection is performed. This is because it is suitable to serve as the above-mentioned paper feed trigger and the start trigger of the post-processing apparatus.

遮蔽部材１０が設けられた搬送路１５の上方に両面印字用の反転路たる搬送路１６があり、この上方に設けられた搬送路１６にもシート状媒体の検知装置として反射型センサ３３を設けている。反射型センサはスペースをとらない利点がある反面、遮蔽部材１０と発光素子２０ａ、受光素子２０ｂを組み合わせたような透過型検知手段に比べて高価である。一方、該透過型検知手段は安価である反面遮蔽部材が回動するため、回動スペースが必要であり、スペースを大きくとってしまう。   Above the conveyance path 15 where the shielding member 10 is provided, there is a conveyance path 16 that is a reverse path for double-sided printing, and a reflection type sensor 33 is also provided on the conveyance path 16 provided above the conveyance path 16 as a sheet-like medium detection device. ing. The reflection type sensor has the advantage of not taking up space, but is more expensive than the transmission type detection means in which the shielding member 10 is combined with the light emitting element 20a and the light receiving element 20b. On the other hand, the transmission type detecting means is inexpensive, but on the other hand, since the shielding member is rotated, a rotation space is required, and a large space is required.

例示の画像形成装置において、搬送路１６における反射型センサ３３の部位に、仮に透過型検知手段を設置しようとすると、遮蔽部材の回動軸を新たに設置しなければならず、画像形成装置の高さ方向の寸法が大きくなってしまう。   In the illustrated image forming apparatus, if the transmission type detection means is to be installed at the part of the reflection type sensor 33 in the conveyance path 16, the rotation shaft of the shielding member must be newly installed. The dimension in the height direction becomes large.

一方、下の搬送路１５の上方には、定着後のシート状媒体を反転路である搬送路１６に送り出す進路（つなぎ搬送路１８）とローラ４ａ、４ｂに送り出す進路とに切り換える分岐爪１７の軸１１が設けられている。そこで、上の搬送路１６における検知手段として反射型を用いることでスペース効率を優先し、下の搬送路１５における検知手段として軸１１を利用した透過型の検知手段を採用することにより軸の新設によるスペースの増大を回避しつつ、コスト上昇もある程度抑えることができた。   On the other hand, above the lower conveyance path 15, there is a branch claw 17 for switching between a course (connecting conveyance path 18) for sending the sheet-like medium after fixing to the conveyance path 16 as a reversing path and a course for feeding to the rollers 4a and 4b. A shaft 11 is provided. Therefore, space efficiency is prioritized by using a reflection type as the detection means in the upper conveyance path 16, and a new axis is established by adopting a transmission type detection means using the shaft 11 as the detection means in the lower conveyance path 15. While avoiding an increase in space due to, cost increases could be suppressed to some extent.

この発明は、上下に２つの搬送路を有し、一方の搬送路から他方の搬送路にシート状媒体の進路を切り換える分岐手段を備え両面画像形成可能な画像形成装置に適用することにより、スペースの増大を回避しつつ、コスト上昇もある程度抑えた画像形成装置となすことができ有益である。   The present invention is applied to an image forming apparatus that has two conveying paths at the top and bottom and includes a branching unit that switches the path of the sheet-like medium from one conveying path to the other conveying path, and is capable of forming a double-sided image. Therefore, it is possible to obtain an image forming apparatus in which an increase in cost is suppressed to some extent while avoiding an increase in the image quality.

この発明が適用される画像形成装置外観斜視図である。1 is an external perspective view of an image forming apparatus to which the present invention is applied. 画像形成装置の内部構成を説明した概略の説明図である。1 is a schematic explanatory diagram illustrating an internal configuration of an image forming apparatus. 排紙部近傍の部分拡大断面図である。FIG. 4 is a partial enlarged cross-sectional view in the vicinity of a paper discharge unit. 分岐爪、遮蔽部材およびこれらを支持する軸などを備えたユニットの外観斜視図である。It is an external appearance perspective view of a unit provided with a branch claw, a shielding member, a shaft for supporting these, and the like. 遮蔽部材の基端部を示した部分断面図である。It is the fragmentary sectional view which showed the base end part of the shielding member. 遮蔽部材が透過型センサを遮蔽している状態を説明した図である。It is a figure explaining the state which the shielding member has shielded the transmissive | pervious sensor. 遮蔽部材が透過型センサから退避して遮蔽を解除している状態を説明した図である。It is the figure explaining the state which the shielding member retracted | retracted from the transmissive | pervious sensor and has released shielding. 遮蔽部材が透過型センサを遮蔽している状態を説明した図である。It is a figure explaining the state which the shielding member has shielded the transmissive | pervious sensor. 遮蔽部材がシート状媒体により押し上げられて透過型センサから退避して遮蔽を解除している状態を説明した図である。It is a figure explaining the state which the shielding member was pushed up by the sheet-like medium, evacuated from the transmission type sensor, and has released the shielding.

符号の説明Explanation of symbols

１０ 遮蔽部材
１１ 軸
１７ 分岐爪 10 shielding member 11 shaft 17 branching claw

Claims (7)

シート状媒体の有無を検知するシート状媒体検知装置において、
シート状媒体を搬送する搬送手段と、
発光部及び受光部を一対で有する透過型検知手段と、
前記搬送手段によりシート状媒体が搬送される搬送経路と、
前記搬送経路に回動自在に設けられ該シート状媒体の搬送方向を切り換える分岐手段と、
前記分岐手段の回動中心軸と同一軸に支持されて回動自在であって、前記搬送経路に設けられ、その自由端部が前記発光部と前記受光部との間に位置して前記発光素子から出て前記受光部へ向かう光を途中で遮断する遮蔽状態となる回動位置と、該自由端部が前記発光部と前記受光部との間に位置しないことにより前記発光素子から出て前記受光部へ向かう光が遮断されることなく前記受光部に受光される非遮蔽状態となる回動位置、をとることができ、これら遮蔽状態となる回動位置と非遮蔽状態となる回動位置間の切り換えを、前記搬送路でのシート状媒体の搬送に伴って回動する遮蔽手段と、
前記遮蔽手段の自重による回転を該遮蔽手段が前記遮蔽状態となる回転位置で止めるストッパ機能部を有し、このストッパ機能部は当該シート状媒体検知装置の本体部からなり、
前記遮蔽手段は、前記遮蔽状態のもとで、前記搬送路を進むシート状媒体の先端部により押動されて該遮蔽状態から前記非遮蔽状態を経て、再び前記遮蔽状態に復帰する過程で、前記透過型検知手段の信号遮蔽状態を切り換えることを特徴とするシート状媒体検知装置。 In a sheet-like medium detection device that detects the presence or absence of a sheet-like medium,
Conveying means for conveying the sheet-like medium;
Transmissive detection means having a pair of light emitting part and light receiving part;
A transport path through which the sheet-like medium is transported by the transport means;
A branching means that is rotatably provided in the transport path and switches the transport direction of the sheet-like medium;
It is supported on the same axis as the rotation center axis of the branching means and is rotatable, and is provided in the transport path, and its free end is located between the light emitting part and the light receiving part, and the light emission. A rotating position where the light exits from the element and goes to the light receiving part is blocked in the middle, and the free end part is not located between the light emitting part and the light receiving part, and thus the light exits from the light emitting element. The rotation position where the light receiving portion is received by the light receiving portion without being blocked and the rotation position where the light receiving portion is not shielded can be taken. Shielding means for rotating the position according to the conveyance of the sheet medium in the conveyance path;
A stopper function unit that stops rotation of the shielding unit due to its own weight at a rotation position where the shielding unit is in the shielding state, and the stopper function unit includes a main body of the sheet-like medium detection device;
In the process of returning to the shielding state again from the shielding state through the non-shielding state, the shielding means is pushed by the leading end of the sheet-like medium traveling in the conveyance path under the shielding state. A sheet-like medium detecting apparatus, wherein the signal shielding state of the transmission type detecting means is switched . 請求項１記載のシート状媒体検知装置において、
前記遮蔽手段は前記分岐手段の回動と独立して回動可能であることを特徴とするシート状媒体検知装置。 The sheet-like medium detection device according to claim 1,
The sheet-like medium detection device, wherein the shielding means is rotatable independently of the turning of the branching means. 請求項２に記載のシート状媒体検知装置において、
前記遮蔽手段はその基端部が、自重による回転力で回転するように前記分岐手段の回動軸に嵌合していることを特徴とするシート状媒体検知装置。 In the sheet-like medium detection device according to claim 2,
The sheet-like medium detecting device, wherein the shielding means is fitted to a turning shaft of the branching means so that a base end portion thereof is rotated by a rotational force due to its own weight. 請求項１乃至３の何れかに記載のシート状媒体検知装置において、
前記遮蔽手段は前記搬送路上、定着装置と排紙ローラの間に配置されていることを特徴とするシート状媒体検知装置。 In the sheet-like medium detection device according to any one of claims 1 to 3,
The sheet medium detecting device, wherein the shielding means is disposed between the fixing device and a paper discharge roller on the conveyance path. 請求項４に記載のシート状媒体検知装置において、
前記遮蔽手段が設けられた前記搬送路の上方にも搬送路があり、この上方に設けられた搬送路にもシート状媒体の検知装置が設けられていて、その検知装置は反射型検知装置を用いていることを特徴とするシート状媒体検知装置。 In the sheet-like medium detection device according to claim 4 ,
There is also a conveyance path above the conveyance path where the shielding means is provided, and a sheet-like medium detection device is also provided above the conveyance path, and the detection device is a reflection type detection device. A sheet-like medium detection device characterized by being used. 請求項５記載のシート状媒体検知装置において、
前記上方の搬送路は両面印字用の反転路であり、前記分岐手段は、定着後のシート状媒体を前記反転路に送り出す進路と前記排紙ローラに送り出す進路とに切り換えるものであることを特徴とするシート状媒体検知装置。 In the sheet-like medium detection device according to claim 5,
The upper conveyance path is a reversing path for double-sided printing, and the branching means switches between a path for feeding the fixed sheet-like medium to the reversing path and a path for feeding to the paper discharge roller. A sheet-like medium detection device. 上下に２つの搬送路を有し、一方の搬送路から他方の搬送路にシート状媒体の進路を切り換える分岐手段を備え両面画像形成可能な画像形成装置において、請求項１至６の何れかに記載のシート状媒体検知装置を備えたことを特徴とする画像形成装置。   7. The image forming apparatus according to claim 1, wherein the image forming apparatus has two transport paths on the upper and lower sides and includes a branching unit that switches a path of the sheet-like medium from one transport path to the other transport path and capable of forming a double-sided image. An image forming apparatus comprising the sheet-like medium detection device described above.
JP2004250353A 2004-08-30 2004-08-30 Sheet-like medium detection device and image forming apparatus Expired - Fee Related JP4279752B2 (en)

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