JPH10153913A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device which reduces cost, saves space, and also maintains a desired positional relationship between a latent-image carrier and an opposite member by composing the abutting face of a position fixing member out of the peripheries of three disks capable of abutting on a photoreceptor independently. SOLUTION: The position fixing member 10a has a shape in which the three disks 100a, 101a, and 102a of different outside diameters, three stages, each having its thickness, overlap each other, and they are pierced with the rear shaft 2a of a developing roller so that the smallest-outside-diameter disk 100a is situated on the middle side of the developing roller shaft. Normally, the periphery of the disk having the second largest outside diameter abuts on the tube stock 1a of the photoreceptor. In case a development gap has become wide compared to a gap that is set normally, the position fixing member is moved to make the periphery of the disk having the smallest outside diameter abut on the stock tube of the photoreceptor.

Description

【発明の詳細な説明】DETAILED DESCRIPTION OF THE INVENTION

【０００１】[0001]

【発明の属する技術分野】本発明は、複写機、ファクシ
ミリ、プリンター等の画像形成装置に係り、詳しくは、
表面が潜像担持体に対向する対向部材を備えた画像形成
装置における該対向部材の位置決め機構の改良に関する
ものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as a copying machine, a facsimile, and a printer.
The present invention relates to an improvement in a positioning mechanism of an opposing member in an image forming apparatus having an opposing member whose surface opposes a latent image carrier.

【０００２】[0002]

【従来の技術】従来の画像形成装置においては、潜像担
持体としての感光体ドラムに対して所定の位置関係を保
って対向させる種々の対向部材が設けられている。2. Description of the Related Art In a conventional image forming apparatus, various opposing members are provided to oppose a photosensitive drum as a latent image carrier while maintaining a predetermined positional relationship.

【０００３】例えば、対向部材の１例として、現像剤を
表面に担持し感光体ドラムとの対向部である現像領域に
現像剤を搬送する現像剤担持体がある。従来、現像剤担
持体としての例えば現像スリーブを、該表面が潜像担持
体としての例えば感光体ドラム表面に所定の間隔（以
下、現像ギャップという）を保ちつつ対向するように設
け、この対向部で現像スリーブ上の現像剤が感光体ドラ
ム上の潜像に供給されるように構成されたものが種々知
られている。[0003] For example, as an example of the facing member, there is a developer carrier that carries a developer on the surface thereof and conveys the developer to a developing area which is a portion facing the photosensitive drum. Conventionally, for example, a developing sleeve as a developer carrier is provided such that the surface faces a surface of a photosensitive drum as a latent image carrier while maintaining a predetermined interval (hereinafter referred to as a developing gap). There are known various types in which a developer on a developing sleeve is supplied to a latent image on a photosensitive drum.

【０００４】上記のような画像形成装置においては、現
像ギャップが所望の間隔と異なってしまうと、画像濃度
が予期せずに濃くなったり薄くなったりしてしまう場合
があるため、現像ギャップを所望の間隔に保つ位置決め
機構を設けることが要求される。このため、従来の画像
形成装置においては、現像スリーブ両端部に、感光体ド
ラムに対して突き当てるコロなどの部材を設け、現像ギ
ャップを所望の間隔に保つようにしたものが一般的に知
られていた。In the above-described image forming apparatus, if the developing gap is different from a desired interval, the image density may unexpectedly increase or decrease. It is required to provide a positioning mechanism for keeping the distance between the two. For this reason, in a conventional image forming apparatus, it is generally known that a member such as a roller abutting against a photosensitive drum is provided at both ends of a developing sleeve so that a developing gap is maintained at a desired interval. I was

【０００５】また従来、現像ギャップを精度良く保つた
め、現像剤担持体としての現像ローラを有する現像器ご
と、その現像器上方に位置する感光体ドラムに対して上
下移動させる上下用カムと、上下用カムと現像器との間
に介在する偏心ローラとを設け、偏心ローラの回転によ
って現像器の上昇下降を小刻みに行えるようにして、現
像ギャップを精度良く保つように構成したものも提案さ
れている（例えば、実開昭６２−２０５８号公報参
照）。Conventionally, in order to maintain a developing gap with high precision, a developing device having a developing roller as a developer carrying member, an up / down cam for vertically moving a photosensitive drum positioned above the developing device, An eccentric roller interposed between the developing cam and the developing device is provided, and the developing device can be raised and lowered in small increments by rotating the eccentric roller, so that the developing gap is accurately maintained. (See, for example, Japanese Utility Model Laid-Open No. 62-2058).

【０００６】また、現像スリーブ回転軸方向の両端部に
外周面に段差を形成した突き当てコロを設け、突き当て
コロの段差の高い面を感光体ドラムに当接させて現像ギ
ャップを一定に保つよう構成したものも提案されている
（例えば、実開昭６０−６０７６８号公報参照）。Also, abutting rollers having a step formed on the outer peripheral surface are provided at both ends in the direction of the rotation axis of the developing sleeve, and the surface of the abutting roller having a high step is brought into contact with the photosensitive drum to keep the developing gap constant. A device configured as described above has also been proposed (for example, see Japanese Utility Model Application Laid-Open No. 60-60768).

【０００７】ところで、現像スリーブ軸方向、即ち画像
の幅方向が長く形成されている画像形成装置も知られて
いるが、この種の画像形成装置においては、突き当てコ
ロなどを用いて現像ギャップを所望の間隔に保とうとし
ても、部品の寸法精度のバラツキの影響を受けて画像の
幅方向で現像ギャップが異なってしまうことがあり、そ
の結果、形成画像の左右で濃度差がでてしまうことがあ
った。[0007] By the way, an image forming apparatus in which the developing sleeve axial direction, that is, the image width direction is formed long, is also known. In this type of image forming apparatus, a developing gap is formed by using an abutting roller or the like. Even if the desired spacing is maintained, the development gap may differ in the width direction of the image due to the variation in the dimensional accuracy of the parts, and as a result, a density difference may occur between the left and right sides of the formed image. was there.

【０００８】この不具合については、上記実開昭６２−
２０５８号公報で提案されている構成において、現像ロ
ーラ回転軸の両端部に設けた上下用カムと偏心ローラに
より、現像ローラの軸方向における片側ごとに現像ギャ
ップを調整して部品の寸法精度のバラツキを吸収し、現
像ギャップを形成画像の左右で一定に保つことで解消す
ることも考えられる。[0008] Regarding this problem,
In the configuration proposed in Japanese Patent Application Laid-Open No. 2058, the development gap is adjusted for each side in the axial direction of the developing roller by means of up and down cams and eccentric rollers provided at both ends of the developing roller rotating shaft, thereby causing variations in dimensional accuracy of parts. It is also conceivable to solve the problem by absorbing the development gap and keeping the development gap constant at the left and right sides of the formed image.

【０００９】[0009]

【発明が解決しようとする課題】ところが、上記実開昭
６０−６０７６８号公報で示されているように突き当て
コロを用いて現像ギャップを所望の間隔に保つようにし
た方法においては、突き当てコロと感光体ドラムとの当
接部にトナー等の異物が入り込み、特に堅い異物が入り
込んだ場合には、突き当てコロや感光体ドラムが傷つ
き、異物が除去された後も傷の付いた部分だけ現像ギャ
ップに誤差が生じてしまうことがある。そして、現像ギ
ャップをもとの間隔に戻すために傷ついた突き当てコロ
や感光体ドラムを交換すると交換のための部品コストが
増大するという不具合があった。However, in the method disclosed in Japanese Utility Model Application Laid-Open No. 60-60768, a developing roller is used to maintain a development gap at a desired interval. If foreign matter such as toner enters the contact area between the roller and the photoconductor drum, especially if hard foreign matter enters, the abutting roller or the photoconductor drum will be damaged, and the damaged area will remain even after the foreign matter is removed. Only an error may occur in the developing gap. In addition, there is a problem that replacing the damaged abutting roller or the photosensitive drum in order to return the developing gap to the original interval increases the cost of parts for replacement.

【００１０】上記感光体ドラムと突き当てコロとの当接
部への異物の侵入については、上記実開昭６０−６０７
６８号公報で提案されている方法においては、現像スリ
ーブ上のトナー等の異物がスリーブ端部に広がろうとす
るのを、突き当てコロに形成された段差部で規制でき、
現像スリーブ側から突き当てコロと感光体ドラムとの当
接部に異物が入り込むことは防止できる。しかしなが
ら、上記当接部の上方から異物が入り込もうとしたとき
は、突き当てコロの段差部ではその侵入を規制すること
ができず異物の侵入による不具合の発生を避けることは
できない。Regarding the intrusion of foreign matter into the abutting portion between the photosensitive drum and the abutting roller, the above-mentioned Japanese Utility Model Application Laid-Open No.
According to the method proposed in Japanese Patent Publication No. 68, it is possible to restrict foreign substances such as toner on the developing sleeve from spreading to the end of the sleeve by a step formed on the abutting roller.
Foreign matter can be prevented from entering the contact portion between the abutting roller and the photosensitive drum from the developing sleeve side. However, when foreign matter tries to enter from above the contact portion, the invasion cannot be restricted at the stepped portion of the abutting roller, and it is not possible to avoid a problem caused by the invasion of foreign matter.

【００１１】また、上記実開昭６２−２０５８号公報で
提案されている方法によれば、上下用カム、偏心ローラ
等の部品点数が増えて装置が複雑化するために、部品コ
ストが増大してしまうこともあった。According to the method proposed in Japanese Utility Model Application Laid-Open No. 62-2058, the number of parts such as the vertical cam and the eccentric roller increases, and the apparatus becomes complicated. Sometimes it happened.

【００１２】上記のような、位置決め機構におけるコス
トの問題は、感光体ドラムと現像スリーブとの間の位置
決めのみでなく、感光体ドラムとの間に所定の位置関係
をもつように画像形成装置に対向部材が設けられている
場合は、感光体ドラムと対向部材との位置決めを行う位
置決め機構においても同様に起こりうることである。The problem of the cost of the positioning mechanism as described above is not only in the positioning between the photosensitive drum and the developing sleeve, but also in the image forming apparatus so as to have a predetermined positional relationship with the photosensitive drum. When an opposing member is provided, the same can occur in a positioning mechanism that positions the photosensitive drum and the opposing member.

【００１３】本発明は以上の問題点に鑑みなされたもの
であり、その第１の目的とするところは、低コスト化を
図りつつ、潜像担持体と対向部材とを所望の位置関係に
維持できる画像形成装置を提供することである。The present invention has been made in view of the above problems, and a first object of the present invention is to maintain a desired positional relationship between a latent image carrier and an opposing member while reducing costs. It is an object of the present invention to provide an image forming apparatus capable of performing the above.

【００１４】また、その第２の目的とするところは、低
コストを図りつつ、現像ギャップを所望の間隔に維持し
て、形成画像濃度を所望の濃度に維持できる画像形成装
置を提供することである。A second object of the present invention is to provide an image forming apparatus capable of maintaining a developing gap at a desired interval and maintaining a formed image density at a desired density while achieving low cost. is there.

【００１５】[0015]

【課題を解決するための手段】上記目的を達成するため
に、請求項１の画像形成装置は、表面に潜像を担持する
潜像担持体と、該潜像担持体に対向して設けられる対向
部材と、該潜像担持体と該対向部材との位置関係が所定
の位置関係になるよう該潜像担持体に対する該対向部材
の位置を決める位置決め手段とを有する画像形成装置に
おいて、上記位置決め手段を、それぞれ単独で上記潜像
担持体に当接可能な複数の当接面を有する位置保持部材
と、上記潜像担持体に当接する上記当接面を切り替える
当接面切り替え手段とから構成したことを特徴とするも
のである。In order to achieve the above object, an image forming apparatus according to the present invention is provided with a latent image carrier for carrying a latent image on a surface thereof, and opposed to the latent image carrier. An image forming apparatus comprising: an opposing member; and positioning means for determining a position of the opposing member with respect to the latent image carrier such that a positional relationship between the latent image carrier and the opposing member becomes a predetermined positional relationship. The means comprises a position holding member having a plurality of contact surfaces each capable of independently contacting the latent image carrier, and contact surface switching means for switching the contact surface contacting the latent image carrier. It is characterized by having done.

【００１６】一般的に、潜像担持体は硬質の材質で構成
されており、潜像担持体と当接面との間に異物が入り込
んだときは、当接面側に傷が付きやすい。Generally, the latent image carrier is made of a hard material, and when foreign matter enters between the latent image carrier and the contact surface, the contact surface is easily damaged.

【００１７】請求項１の画像形成装置においては、潜像
担持体表面と位置保持部材の当接面との間に異物が侵入
し、当接面が傷ついて潜像担持体と対向部材との位置関
係に誤差が生じた場合に、当接面切り替え手段で潜像担
持体に当接する当接面を替える。これにより、傷の付い
ていない新たな当接面を潜像担持体に当接させる。In the image forming apparatus according to the first aspect, foreign matter enters between the surface of the latent image carrier and the abutting surface of the position holding member, and the abutting surface is damaged, so that the latent image carrier and the opposing member are damaged. If an error occurs in the positional relationship, the contact surface switching means changes the contact surface that contacts the latent image carrier. As a result, a new contact surface that is not damaged is brought into contact with the latent image carrier.

【００１８】特に、請求項２の画像形成装置は、請求項
１の画像形成装置において、前記潜像担持体に当接する
前記当接面が異なることにより、潜像担持体表面と上記
対向部材との位置関係が異なるよう上記位置保持部材を
形成したことを特徴とするものである。[0018] In particular, the image forming apparatus according to the second aspect is the image forming apparatus according to the first aspect, wherein the contact surface that comes into contact with the latent image carrier is different, so that the surface of the latent image carrier and the opposing member are separated from each other. Wherein the position holding member is formed so that the positional relationship is different.

【００１９】請求項２の画像形成装置においては、所望
の位置関係が得られる当接面を選択して潜像担持体に当
接させる。In the image forming apparatus of the present invention, a contact surface at which a desired positional relationship is obtained is selected and brought into contact with the latent image carrier.

【００２０】また、特に請求項３の画像形成装置は、請
求項２の画像形成装置において、前記位置保持部材の前
記複数の当接面を、段階的に外径が大きくなる複数の外
周面で形成したことを特徴とするものである。According to a third aspect of the present invention, in the image forming apparatus of the second aspect, the plurality of abutting surfaces of the position holding member are formed by a plurality of outer peripheral surfaces whose outer diameters gradually increase. It is characterized by having been formed.

【００２１】請求項３の画像形成装置においては、段階
的に外径が大きくなる複数の外周面のうち、外径が小さ
い外周面を潜像担持体に当接させると、潜像担持体と対
向部材との間隔が狭くなり、外径が大きい外周面を潜像
担持体に当接させると、上記間隔が広くなる。潜像担持
体と対向部材との位置関係を所望の位置関係にする際、
潜像担持体に当接させる当接面の外径を段階的に大き
く、又は小さくしていき、所望の位置関係に徐々に近づ
けていく。According to the third aspect of the present invention, when the outer peripheral surface having a smaller outer diameter is brought into contact with the latent image carrier among a plurality of outer peripheral surfaces having an outer diameter gradually increasing, the latent image carrier is When the distance between the opposing member and the outer peripheral surface having a large outer diameter is brought into contact with the latent image carrier, the distance is increased. When making the positional relationship between the latent image carrier and the opposing member a desired positional relationship,
The outer diameter of the contact surface to be brought into contact with the latent image carrier is gradually increased or decreased to gradually approach a desired positional relationship.

【００２２】また、請求項４の画像形成装置は、請求項
１の画像形成装置において、前記複数の当接面が、上記
潜像担持体のそれぞれ異なる位置に当接するよう前記位
置保持部材及び当接面切り替え手段を構成したことを特
徴とするものである。According to a fourth aspect of the present invention, in the image forming apparatus of the first aspect, the position holding member and the contacting member are arranged such that the plurality of contact surfaces contact different positions of the latent image carrier. A contact surface switching means is provided.

【００２３】請求項４の画像形成装置においては、潜像
担持体に当接させる当接面を替えることによって当接面
が当接する潜像担持体上の位置を移動させる。これによ
り、潜像担持体と当接面との間に異物が混入し、潜像担
持体が傷ついて潜像担持体と対向部材との位置関係が予
期せずに変化してしまった場合に、傷のない潜像担持体
表面に上記当接面を当接させる。In the image forming apparatus according to the fourth aspect, the position on the latent image carrier where the contact surface comes into contact is moved by changing the contact surface that comes into contact with the latent image carrier. As a result, when foreign matter is mixed between the latent image carrier and the contact surface, the latent image carrier is damaged, and the positional relationship between the latent image carrier and the facing member is changed unexpectedly. Then, the contact surface is brought into contact with the surface of the latent image carrier having no damage.

【００２４】特に、請求項５の画像形成装置は、請求項
４の画像形成装置において、前記位置保持部材を、該画
像形成装置の前記潜像担持体表面から所定距離離間した
位置に取り付け可能な軸部と、該軸部に設けられ、該軸
部を上記画像形成装置に取り付ける方向を正又は逆方向
で変えることにより上記潜像担持体に当接する上記当接
面が入れ替わる当接面をそれぞれ有する２つの凸部とか
ら構成したことを特徴とするものである。In particular, in the image forming apparatus according to the fifth aspect, in the image forming apparatus according to the fourth aspect, the position holding member can be mounted at a position separated by a predetermined distance from the surface of the latent image carrier of the image forming apparatus. A shaft portion and a contact surface provided on the shaft portion, wherein the contact surface that comes into contact with the latent image carrier by changing the direction in which the shaft portion is attached to the image forming apparatus in a forward or reverse direction is replaced. And two convex portions.

【００２５】請求項５の画像形成装置においては、一方
の凸部の当接面が潜像担持体のある部分に当接し、潜像
担持体と対向部材との位置関係を所望の位置関係に維持
する。そして、上記当接面と潜像担持体の当接部に異物
が侵入し、この当接面や潜像担持体表面部分に傷が付い
て上記位置関係が予期せずに変化してしまったとき、凸
部が設けられている軸部を左右逆にして装置内に取り付
け、上記と異なる凸部の当接面を潜像担持体表面の上記
当接面が当接していた部分以外の部分に当接させる。In the image forming apparatus according to the fifth aspect, the contact surface of the one convex portion contacts a certain portion of the latent image carrier, and the positional relationship between the latent image carrier and the opposing member is set to a desired positional relationship. maintain. Then, foreign matter intruded into the contact portion between the contact surface and the latent image carrier, and the contact surface and the surface portion of the latent image carrier were damaged, and the positional relationship was unexpectedly changed. At this time, the shaft portion provided with the convex portion is mounted in the apparatus with the left and right reversed, and the contact surface of the convex portion different from the above is a portion of the surface of the latent image carrier other than the portion where the above-mentioned contact surface is in contact. Contact.

【００２６】上記第２の目的を達成するために請求項６
の画像形成装置は、請求項１、２、３、４又は５の画像
形成装置において、該潜像担持体上の潜像を現像するた
めの現像剤を表面に担持する現像剤担持体を有し、前記
位置決め手段により前記潜像担持体表面と上記現像剤担
持体表面との間の間隔を所定の間隔に保つよう該潜像担
持体に対する該現像剤担持体の位置を決めることを特徴
とするものである。According to a sixth aspect of the present invention, in order to achieve the second object,
The image forming apparatus according to claim 1, further comprising a developer carrier for carrying a developer for developing a latent image on the latent image carrier on a surface of the image forming apparatus according to claim 1, 2, 3, 4, or 5. The position of the developer carrier with respect to the latent image carrier is determined by the positioning means so as to keep a distance between the surface of the latent image carrier and the surface of the developer carrier at a predetermined interval. Is what you do.

【００２７】請求項６の画像形成装置においては、潜像
担持体表面と位置保持部材の当接面との間に異物が侵入
し、当接面が傷ついて現像ギャップに誤差が生じた場合
に、当接面切り替え手段で潜像担持体に当接する当接面
を替える。これにより、傷の付いていない新たな当接面
を潜像担持体に当接させて、現像ギャップを所望の間隔
に維持する。In the image forming apparatus according to the present invention, when foreign matter enters between the surface of the latent image carrier and the contact surface of the position holding member and the contact surface is damaged, an error occurs in the developing gap. The contact surface that contacts the latent image carrier is changed by the contact surface switching unit. As a result, a new contact surface that has not been damaged is brought into contact with the latent image carrier, and the development gap is maintained at a desired interval.

【００２８】[0028]

【発明の実施の形態】以下、本発明を一成分現像装置を
有する画像形成装置に適用した実施形態について説明す
る。 ［実施形態１］図１は本実施形態に係る画像形成装置に
おける現像装置近傍の概略構成図である。この画像形成
装置は、トナー貯溜部としてのトナーホッパ６と、潜像
担持体としての感光体ドラム１と、対向部材の一例であ
る現像剤担持体としての現像ローラ２と、ホッパ内のト
ナーを現像ローラ２に供給する供給ローラ４と、トナー
ホッパ内部のトナーを撹拌して供給ローラ４に供給する
トナー撹拌部材５ａ，５ｂと、現像ローラ２上のトナー
の層厚を均す現像剤規制部材としての薄層化ブレード３
とを有している。DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to an image forming apparatus having a one-component developing device will be described below. [Embodiment 1] FIG. 1 is a schematic configuration diagram of the vicinity of a developing device in an image forming apparatus according to the present embodiment. The image forming apparatus includes a toner hopper 6 serving as a toner storage unit, a photosensitive drum 1 serving as a latent image carrier, a developing roller 2 serving as a developer carrier which is an example of an opposing member, and developing toner in the hopper. A supply roller 4 for supplying to the roller 2; toner agitating members 5a and 5b for agitating the toner inside the toner hopper and supplying to the supply roller 4; and a developer regulating member for uniforming the layer thickness of the toner on the developing roller 2 Thinning blade 3
And

【００２９】図１において、感光体ドラム１は矢印の方
向に回転している。この現像器では、ホッパ６内のトナ
ーは、第１アジテーター５ａ、及び、第２アジテーター
５ｂにより撹拌、搬送される。現像ローラ２は矢印の方
向に回転し、供給ローラ４と接触する。供給ローラ４は
現像ローラ２と順方向に回転し、トナーに負の摩擦帯電
電荷を与える。そして現像ローラ２の回転に対してトレ
ーリング方向から薄層化ブレード３が現像ローラー２に
当接し逆帯電トナー及び未帯電トナーを剥離するととも
にトナー層厚の均一化を行うことで現像ローラ２上のト
ナーは適正なトナー層厚に均され、現像領域に搬送され
る。現像領域では、感光体ドラムと現像ローラ２との現
像ギャップは０．１５mmに設定されており、現像ローラ
２上のトナーは感光体ドラム１の電荷部に向かって飛翔
し、非接触現像が行われる。In FIG. 1, the photosensitive drum 1 is rotating in the direction of the arrow. In this developing device, the toner in the hopper 6 is stirred and transported by the first agitator 5a and the second agitator 5b. The developing roller 2 rotates in the direction of the arrow and comes into contact with the supply roller 4. The supply roller 4 rotates in the forward direction with respect to the developing roller 2, and applies a negative triboelectric charge to the toner. The rotation of the developing roller 2 causes the thinning blade 3 to come into contact with the developing roller 2 in the trailing direction to separate the oppositely charged toner and the uncharged toner and to make the toner layer thickness uniform, so that the toner layer thickness is reduced. Is leveled to an appropriate toner layer thickness and transported to the developing area. In the developing area, the developing gap between the photosensitive drum and the developing roller 2 is set to 0.15 mm, and the toner on the developing roller 2 flies toward the charged portion of the photosensitive drum 1 to perform non-contact development. Will be

【００３０】本実施形態の画像形成装置においては、現
像ギャップが０．１５mmと狭く設定されており、この現
像ギャップが多少変化しても画像濃度等の現像性能に大
きく影響する。このため、本実施形態においては、現像
ギャップを所望の間隔に精度良く維持できるように構成
している。以下、本実施形態の特徴部としての現像ギャ
ップを所望の間隔に精度良く維持する構成について説明
する。In the image forming apparatus of the present embodiment, the developing gap is set as narrow as 0.15 mm, and even if this developing gap is slightly changed, the developing performance such as image density is greatly affected. For this reason, the present embodiment is configured so that the developing gap can be maintained at a desired interval with high accuracy. Hereinafter, a description will be given of a configuration for accurately maintaining the developing gap as a characteristic portion of the present embodiment at a desired interval.

【００３１】図２は、本実施形態の特徴部を示す現像領
域近傍の平面図である。感光体ドラム１の両端には、感
光層が塗布されていない感光体素管部１ａ、１ｂが形成
されている。また、現像ローラ２の奥側軸部２ａには位
置保持部材１０ａ、位置保持部材１０ａと現像ローラ２
との間隔を保つためのカラー１１ａ，１１ｂ、 位置保
持部材１０ａとカラーを奥側軸部に固設するためのＥリ
ング１２ａが設けられており、手前側軸部２ｂには位置
保持部材１０ｂ、カラー１１ｃ、１１ｄ、 Ｅリング１
２ｂが設けられている。FIG. 2 is a plan view showing a characteristic portion of the present embodiment in the vicinity of a developing region. At both ends of the photosensitive drum 1, photosensitive body tube portions 1a and 1b to which a photosensitive layer is not applied are formed. The position holding member 10a, the position holding member 10a and the developing roller 2 are provided on the rear shaft portion 2a of the developing roller 2.
And an E-ring 12a for fixing the collar to the rear shaft portion, and a position holding member 10b for the front shaft portion 2b. Collar 11c, 11d, E-ring 1
2b is provided.

【００３２】上記位置保持部材１０ａは、奥側軸部２ａ
に設けられたとき、外径が３段階に大きく形成されかつ
それぞれ厚みのある３つの円盤部１００ａ、１０１ａ、
１０２ａが積み重なった形状をしており、最も外径が小
さい円盤部１００ａが現像ローラ軸の中央に、最も外径
が大きい円盤部１０２ａが奥側軸部２ａの端部にくるよ
う、奥側軸部２ａに貫通させられている。また、他方の
位置保持部材１０ｂも外径が３段階に大きく形成された
３つの円盤部１００ｂ、１０１ｂ、１０２ｂからなり、
もっとも外径が大きい円盤部１０２ｂが手前側軸部２ｂ
の端部にくるよう、手前側軸部２ｂに設けられている。
この円盤部の外周面が、感光体ドラム１に対する当接面
となっている。The position holding member 10a includes a rear shaft 2a.
, Three outer diameters are formed in three stages, and three thick disk portions 100a, 101a,
102a are stacked so that the disk portion 100a having the smallest outer diameter is located at the center of the developing roller shaft and the disk portion 102a having the largest outer diameter is located at the end of the rear shaft portion 2a. The portion 2a is penetrated. The other position holding member 10b also includes three disk portions 100b, 101b, and 102b whose outer diameters are increased in three stages.
The disk portion 102b having the largest outer diameter is the front shaft portion 2b.
Is provided on the front shaft portion 2b so as to come to the end of the front shaft portion 2b.
The outer peripheral surface of the disk portion is a contact surface with the photosensitive drum 1.

【００３３】上記位置保持部材１０ａの３つの円盤部１
００ａ、１０１ａ、１０２ａの外周面が単独で感光体ド
ラム１の 感光体素管部１ａ、１ｂに当接したとき、現
像ギャップはそれぞれ、０．１３mm、０．１５mm、０．
１７mmとなるように、各円盤部１００ａ、１０１ａ、１
０２ａの外径が設定されている。この現像ギャップの設
定は、他方の位置保持部材１０ｂについても同様なので
説明を省略する。The three disk portions 1 of the position holding member 10a
When the outer peripheral surfaces of the photoconductor drums 100a, 101a, and 102a independently contact the photoconductor drum sections 1a and 1b of the photoconductor drum 1, the developing gaps are 0.13 mm, 0.15 mm, and 0.1 mm, respectively.
Each disk part 100a, 101a, 1
02a is set. The setting of the developing gap is the same for the other position holding member 10b, and therefore the description is omitted.

【００３４】通常作像時は、位置保持部材１０ａ、１０
ｂの中段の円盤部１０１ａ、１０１ｂの外周面が感光体
素管部１ａ、１ｂにそれぞれ当接しており、現像ギャッ
プは０．１５mmに維持されている。しかし、現像ローラ
２、感光体ドラム１、各部材の軸支部材等の部品精度に
バラツキが生じたり、広幅の画像に対応できるよう感光
体ドラム１、現像ローラ２等が軸方向に長い場合、現像
ギャップが所望の間隔に維持できない場合がある。At the time of normal image formation, the position holding members 10a, 10a
The outer peripheral surfaces of the middle disk portions 101a and 101b are in contact with the photosensitive element tube portions 1a and 1b, respectively, and the developing gap is maintained at 0.15 mm. However, if the accuracy of the components such as the developing roller 2, the photosensitive drum 1, and the supporting members of the respective members varies, or if the photosensitive drum 1, the developing roller 2 and the like are long in the axial direction so as to support a wide image, In some cases, the development gap cannot be maintained at a desired interval.

【００３５】図２は、現像ローラ２の奥側近傍の現像ギ
ャップに影響を与える部品精度が悪く、上記のような位
置保持部材１０ａ、１０ｂの通常作像時の配置では奥側
の現像ギャップが広くなってしまう場合の不具合を解消
したものである。この画像形成装置においては、現像ロ
ーラ２の奥側軸部２ａに設けられている位置保持部材１
０ａを、最も外径の小さい円盤部１００ａの外周面を感
光体素管部１ａに当接させている。感光体素管部１ａに
当接させる外周面を変えることは位置保持部材１０ａの
奥側軸部２ａへの固定位置を軸の端部側へ移動させてそ
の間に円盤部１００ａ、１０１ａ、１０２ａの厚みと等
しい長さのカラー１１ａ、１１ｂをはめ込むことによっ
て容易に可能となる。上記のように奥側の位置保持部材
１０ａを移動させることで、奥側の現像ギャップが通常
設定時に比して狭くなるが、奥側の現像ギャップが通常
設定時より広くなっていたため、相殺されて所望の現像
ギャップを得ることができる。FIG. 2 shows that the accuracy of the components affecting the developing gap near the back side of the developing roller 2 is poor, and that the rear side developing gap is small when the position holding members 10a and 10b are arranged at the time of normal image formation. This is a solution to the problem of widening. In this image forming apparatus, the position holding member 1 provided on the rear shaft portion 2a of the developing roller 2
0a, the outer peripheral surface of the disk portion 100a having the smallest outer diameter is brought into contact with the photosensitive element tube portion 1a. Changing the outer peripheral surface to be brought into contact with the photoreceptor tube 1a moves the fixing position of the position holding member 10a to the rear shaft portion 2a toward the end of the shaft, and in the meantime, moves the disk portions 100a, 101a, and 102a. This can be easily achieved by fitting the collars 11a and 11b having the same length as the thickness. By moving the position holding member 10a on the back side as described above, the development gap on the back side is narrower than in the normal setting, but is offset because the development gap on the back side is wider than in the normal setting. Thus, a desired development gap can be obtained.

【００３６】また、長期的に現像を行うことでトナーが
劣化すると、トナーが固まりやすくなったり、帯電が不
十分なったりして現像領域で電荷部に向かって飛翔しに
くくなる。そしてこの結果、画像濃度が低下してしま
う。このような場合に、現像ローラ２の両側に設けてい
る位置保持部材１０ａ、１０ｂを、現像ギャップを狭く
する円盤部１００ａ、１００ｂの外周面が感光体素管部
１ａ、１ｂに当接するように移動させ、現像ギャップを
通常設定時より狭くする。これにより、現像領域におけ
る現像電界を強くし、劣化したトナーでも画像濃度が高
くでるようにして、劣化したトナーの継続使用ができる
ようにする。Further, if the toner is deteriorated due to long-term development, the toner is likely to solidify or insufficiently charged, so that the toner hardly flies toward the charged portion in the development area. As a result, the image density decreases. In such a case, the position holding members 10a and 10b provided on both sides of the developing roller 2 are adjusted so that the outer peripheral surfaces of the disc portions 100a and 100b for narrowing the developing gap are brought into contact with the photosensitive element tube portions 1a and 1b. Move it to make the development gap narrower than in the normal setting. As a result, the developing electric field in the developing area is strengthened, and the image density is increased even with the deteriorated toner, so that the deteriorated toner can be used continuously.

【００３７】上記のように、現像ギャップが形成画像の
左右で異なり、画像濃度に長手方向でのムラが生じてし
まう場合に、位置保持部材１０ａを移動させるという容
易な操作で現像ギャップを左右均一にすることができ、
左右の画像濃度ムラを防止することができる。また、ト
ナーが劣化して画像濃度が低下した場合でも、位置保持
部材１０ａを移動させるという容易な操作で現像ギャッ
プを狭くし、画像濃度を高くすることができるので、劣
化したトナーを交換するコストがかからず、ランニング
コストを低減することができる。 （以下、余白）As described above, when the developing gap is different between the left and right of the formed image and the image density becomes uneven in the longitudinal direction, the developing gap is made uniform by the simple operation of moving the position holding member 10a. Can be
The left and right image density unevenness can be prevented. Further, even when the image density is lowered due to the deterioration of the toner, the developing gap can be narrowed and the image density can be increased by an easy operation of moving the position holding member 10a, so that the cost of replacing the deteriorated toner can be improved. And the running cost can be reduced. (Hereinafter, margin)

【００３８】尚、本実施形態においては、位置保持部材
１０ａ、１０ｂごとにの３つの円盤部１００ａ、１０１
ａ、１０２ａ、１００ｂ、１０１ｂ、１０２ｂを設け、
現像ギャップを３段階に可変にしたが、この円盤部は３
つに限定されるものではない。上記のような効果を得る
のに適当な円盤部の外径と円盤部の個数を、位置保持部
材を設ける画像形成装置の種々の条件に応じて設定する
ことができる。In this embodiment, three disk portions 100a, 101 are provided for each of the position holding members 10a, 10b.
a, 102a, 100b, 101b, 102b are provided,
The developing gap was made variable in three steps.
It is not limited to one. Appropriate outer diameter of the disk portion and the number of the disk portions suitable for obtaining the above-described effects can be set according to various conditions of the image forming apparatus provided with the position holding member.

【００３９】［実施形態２］次に、他の構成からなる位
置保持部材を図１で示した画像形成装置に適用した実施
形態について説明する。図３（ａ）（ｂ）は、実施形態
２にかかる位置保持部材１３ａ、１３ｂを設けた現像領
域近傍の平面図である。現像ローラ２の奥側軸部２ａに
は位置保持部材１３ａ、位置保持部材１３ａを奥側軸部
２ａに固設するためのＥリング１２ａが設けられてお
り、手前側軸部２ｂには位置保持部材１３ｂ、位置保持
部材を手前側軸部２ｂに固設するためのＥリング１２ｂ
が設けられている。[Second Embodiment] Next, an embodiment in which a position holding member having another structure is applied to the image forming apparatus shown in FIG. 1 will be described. FIGS. 3A and 3B are plan views of the vicinity of a development area provided with the position holding members 13a and 13b according to the second embodiment. A position holding member 13a and an E-ring 12a for fixing the position holding member 13a to the rear shaft portion 2a are provided on the rear shaft portion 2a of the developing roller 2, and the position holding member 13a is fixed on the front shaft portion 2b. E-ring 12b for fixing the member 13b and the position holding member to the front shaft portion 2b
Is provided.

【００４０】本実施形態の位置保持部材１３ａは同一外
径でかつ幅を持った２つの凸部としての円盤部１０３
ａ、１０４ａが中空円筒部材に間隔を開けて固設され、
中空円筒部材を長手方向で３つのカラー１０５ａ、１０
６ａ、１０７ａに分割している。このカラー１０５ａ、
１０６ａ、１０７ａのうち、端部の一方にあるのカラー
１０５ａは、他方のカラー１０７ａより短くなってい
る。The position holding member 13a of the present embodiment has a disk portion 103 as two convex portions having the same outer diameter and width.
a, 104a are fixed to the hollow cylindrical member at an interval,
The hollow cylindrical member is divided into three collars 105a, 10
6a and 107a. This color 105a,
The collar 105a at one of the ends of the collars 106a and 107a is shorter than the other collar 107a.

【００４１】装置の初期設定時には、図３（ａ）に示す
ように、位置保持部材１３ａは、短い方のカラー１０５
ａが内側に、長い方のカラー１０７ａが外側にくるよう
奥側軸部２ａに現像ローラ２のローラ部に突き当てて固
設されている。また、他方の位置保持部材１３ｂも位置
保持部材１３ａと同様の形状をしており、装置の初期設
定時には、短い方のカラー１０５ｂが内側に、長い方の
カラー１０７ｂが外側にくるよう手前側軸部２ｂに固設
されている。At the time of initial setting of the apparatus, as shown in FIG. 3A, the position holding member 13a is
The roller a of the developing roller 2 is fixedly mounted on the rear shaft portion 2a such that a is on the inside and the longer collar 107a is on the outside. Also, the other position holding member 13b has the same shape as the position holding member 13a, and at the time of initial setting of the apparatus, the front side shaft is set so that the shorter collar 105b is on the inside and the longer collar 107b is on the outside. It is fixed to the portion 2b.

【００４２】なお、上記位置保持部材１３ａ、１３ｂの
円筒部１０３ａ、１０４ａ、１０３ｂ、１０４ｂの外径
は、各円筒部１０３ａ、１０４ａ、１０３ｂ、１０４ｂ
の外周面が感光体素管部１ａ、１ｂに当接したとき、所
望の現像ギャップが得られるように設定されている。The outer diameters of the cylindrical portions 103a, 104a, 103b, 104b of the position holding members 13a, 13b are determined by the respective cylindrical portions 103a, 104a, 103b, 104b.
Are set such that a desired developing gap is obtained when the outer peripheral surface of the photoconductor comes into contact with the photosensitive element tube portions 1a and 1b.

【００４３】図３（ａ）に示すように画像形成装置内に
位置保持部材１３ａ、１３ｂが設けられているとき、位
置保持部材１３ａにおける内側の円盤部１０３ａ外周面
が感光体素管部１ａに当接し、位置保持部材１３ｂにお
ける内側の円盤部１０３ｂ外周面が感光体素管部１ｂに
当接して所望の現像ギャップを維持している。As shown in FIG. 3 (a), when the position holding members 13a and 13b are provided in the image forming apparatus, the outer peripheral surface of the inner disk portion 103a of the position holding member 13a becomes the photosensitive element tube portion 1a. The outer peripheral surface of the inner disk portion 103b of the position holding member 13b abuts on the photosensitive drum 1b to maintain a desired developing gap.

【００４４】しかし、画像形成装置を長期的に使用して
いると、異物が感光体素管部１ａと位置保持部材１３ａ
の円盤部１０３ａ外周面との間や、感光体素管部１ｂと
位置保持部材１３ｂの円盤部１０３ｂ外周面との間に異
物が入り込み、円盤部１０３ａ、１０３ｂ外周面を傷つ
けてしまったり、時には感光体素管部１ａ、１ｂ側をも
傷つけてしまったりすることがある。そして、このよう
に傷つくと、初期設定されていた現像ギャップが狭くな
ったり、感光体素管部１ａ、１ｂと円盤部１０３ａ、１
０３ｂ外周面との間でがたついたりして現像ギャップが
変わってしまう。この結果、現像ローラ２の回転方向即
ち形成画像の縦方向で画像濃度ムラが発生することがあ
る。また、感光体素管部１ａ、１ｂと円盤部１０３ａ、
１０３ｂ外周面との間に入り込んだ異物が固着して、現
像ギャップを初期設定から大きくしてしまい、形成画像
の縦方向で画像濃度ムラが発生することもある。However, if the image forming apparatus has been used for a long period of time, the foreign matter will be removed from the photosensitive element tube portion 1a and the position holding member 13a.
Foreign matter enters between the outer peripheral surface of the disc portion 103a and the outer peripheral surface of the photosensitive drum portion 1b and the outer peripheral portion of the disc portion 103b of the position holding member 13b, and sometimes damages the outer peripheral surfaces of the disc portions 103a and 103b. In some cases, the photosensitive body tube portions 1a and 1b may be damaged. If such damage occurs, the initially set developing gap becomes narrower, or the photosensitive element tube portions 1a and 1b and the disk portions 103a and 103a,
The development gap changes due to rattling with the outer peripheral surface of the developing roller 03b. As a result, image density unevenness may occur in the rotation direction of the developing roller 2, that is, in the vertical direction of the formed image. In addition, the photosensitive element tube portions 1a and 1b and the disk portion 103a,
Foreign matter that has entered between the outer peripheral surface and the outer peripheral surface of 103b is fixed and the developing gap is increased from the initial setting, so that image density unevenness may occur in the vertical direction of the formed image.

【００４５】図３（ｂ）は、感光体素管部１ａ、１ｂと
円盤部１０３ａ、１０３ｂ外周面との間に異物が入り込
み、現像ギャップを変化させてしまった場合に、位置保
持部材１３ａを奧側軸部２ａに長い方のカラー１０７ａ
が内側になるように固設し直す。また、位置保持部材１
３ｂも手前側軸部２ｂに長い方のカラー１０７ｂが内側
になるように固設し直す。これによって、感光対素管部
１ａ、１ｂには新たな円盤部１０４ａ、１０４ｂの外周
面が当接すると供に、位置保持部材を固設し直す前に円
盤部１０３ａ、１０３ｂ外周面が当接していた感光体素
管部１ａ、１ｂの位置より外側にこの外周面が当接す
る。FIG. 3B shows the position holding member 13a when foreign matter enters between the photoreceptor tube portions 1a and 1b and the outer peripheral surfaces of the disk portions 103a and 103b and changes the developing gap. The longer collar 107a on the back shaft 2a
Reinstall so that is inside. Also, the position holding member 1
3b is fixed to the front shaft portion 2b so that the longer collar 107b is located inside. As a result, the outer peripheral surfaces of the new disk portions 104a and 104b come into contact with the photosensitive pair pipe portions 1a and 1b, and the outer peripheral surfaces of the disk portions 103a and 103b come into contact before the position holding member is fixed again. The outer peripheral surface abuts on the outer side of the position of the photoreceptor tube sections 1a and 1b.

【００４６】上記のように、位置保持部材１３ａ、１３
ｂを固設し直すことによって、円盤部１０４ａ、１０４
ｂの外周面と、この外周面が当接する感光体素管部１
ａ、１ｂの位置との両方が新しくなるので、位置保持部
材１３ａ、１３ｂを固設し直す前に感光体素管部１ａ、
１ｂに当接していた円盤部１０３ａ、１０３ｂの外周面
や感光体素管部１ａ、１ｂなどが傷ついていたり、異物
が固着していたりしても、新たに当接するする感光体素
管部１ａ、１ｂや円盤部の外周面には傷や異物の固着を
なくすことができ、現像ギャップを初期設定に戻すこと
ができる。これにより、形成画像の縦方向での濃度ムラ
の発生を防止することができる。また、感光体ドラム
１、位置保持部材１３ａ、１３ｂとも交換せずに現像ギ
ャップを戻すことができるので、感光体ドラム１、位置
保持部材１３ａ、１３ｂを継続使用でき、ランニングコ
ストを低減することができる。As described above, the position holding members 13a, 13
By re-installing b, the disk portions 104a, 104
b and the photoreceptor tube portion 1 in contact with the outer peripheral surface
Since both the positions a and 1b are new, the photoreceptor tube portions 1a and 1b are fixed before the position holding members 13a and 13b are fixed.
Even if the outer peripheral surfaces of the disk portions 103a and 103b that have been in contact with the photosensitive drum 1b and the photosensitive drums 1a and 1b are damaged or foreign matter is stuck, the photosensitive drum 1a that newly contacts the drum 1a. 1b and the outer peripheral surface of the disk portion can be free from scratches and adhesion of foreign matter, and the developing gap can be returned to the initial setting. As a result, it is possible to prevent density unevenness in the vertical direction of the formed image. Further, since the developing gap can be returned without replacing the photosensitive drum 1 and the position holding members 13a and 13b, the photosensitive drum 1 and the position holding members 13a and 13b can be continuously used, and the running cost can be reduced. it can.

【００４７】なお、本実施形態においては、位置保持部
材１３ａ、１３ｂを両方とも固設し直したが、感光体素
管部１ａ、１ｂと円盤部１０３ａ、１０３ｂの外周面と
の間への異物の混入が、一方のみで発生した場合は、異
物の混入が発生した側の位置保持部材のみを固設し直せ
ばよい。In this embodiment, both of the position holding members 13a and 13b are fixed, but the foreign matter between the photoreceptor tube portions 1a and 1b and the outer peripheral surfaces of the disk portions 103a and 103b is removed. If only one of the position holding members on the side where the foreign matter has occurred has to be fixedly installed.

【００４８】[0048]

【発明の効果】請求項１の画像形成装置によれば、潜像
担持体に当接させる当接面を選択的に切り替えることが
できるので、潜像担持体と当接面との間に異物が入り込
み当接面を傷つけて、潜像担持体と対向部材との位置関
係が狂ってしまっても、傷の付いていない当接面を潜像
担持体に当接させることで位置保持部材を交換すること
なく所望の位置関係に保つことができ、位置保持部材を
交換するのに比して位置保持部材のコストを低減しつつ
潜像担持体と対向部材との位置関係を所望の位置に維持
できるという優れた効果がある。According to the image forming apparatus of the first aspect, the contact surface to be brought into contact with the latent image carrier can be selectively switched, so that a foreign substance is provided between the latent image carrier and the contact surface. Even if the intruded contact surface is damaged and the positional relationship between the latent image carrier and the opposing member is deviated, the position holding member is brought into contact with the non-scratched contact surface by contacting the latent image carrier. A desired positional relationship can be maintained without replacement, and the positional relationship between the latent image carrier and the opposing member can be set to a desired position while reducing the cost of the position holding member compared to replacing the position holding member. There is an excellent effect that it can be maintained.

【００４９】請求項２の画像形成装置によれば、１つの
位置保持部材で潜像担持体と対向部材との位置関係を所
望の位置関係に切り替えることができるので、上記位置
関係を変えるごとに異なる部材を用いるのに比して低コ
スト化を図りつつ所望の位置関係に維持できるという優
れた効果がある。また、位置保持部材を画像形成装置に
設けるだけで位置関係を異なる複数の位置関係に切り替
えることができるので、例えば、コロとカムの両方を装
置に設ける構成など、複数の部材を同時に装置内に設け
るのに比して部材点数を減らすことができ、省スペース
化を図りつつ上記位置関係を所望の位置関係に維持でき
るという優れた効果もある。また、上記位置保持部材を
潜像担持体と対向部材との対向部における両端部近傍に
設け、位置関係を上記対向部の両端部でそれぞれ調整で
きるように構成すれば、上記位置関係が上記対向部の幅
方向でばらついても、幅方向の一方ずつ所望の位置関係
に設定することで容易に幅方向での位置関係の調整がで
きるという優れた効果もある。According to the image forming apparatus of the present invention, the positional relationship between the latent image carrier and the opposing member can be switched to a desired positional relationship with one position holding member. There is an excellent effect that it is possible to maintain a desired positional relationship while reducing costs as compared with using different members. Further, since the positional relationship can be switched to a plurality of different positional relationships only by providing the position holding member in the image forming apparatus, a plurality of members can be simultaneously installed in the apparatus, such as a configuration in which both a roller and a cam are provided in the apparatus. There is also an excellent effect that the number of members can be reduced as compared with the provision, and the above positional relationship can be maintained at a desired positional relationship while saving space. Further, if the position holding member is provided near both ends of the opposing portion of the latent image carrier and the opposing member so that the positional relationship can be adjusted at both ends of the opposing portion, the positional relationship can be adjusted. Even if the portions vary in the width direction, there is an excellent effect that the positional relationship in the width direction can be easily adjusted by setting the desired positional relationship one by one in the width direction.

【００５０】特に、請求項３の画像形成装置によれば、
位置保持部材の外周面を段階的に外径が大きくなるよう
形成しているので、潜像担持体に当接させる外周面を１
つずつ隣の外周面に切り替えることによって潜像担持体
と対向部材との位置関係を少しずつ変えることができ、
特別な部材点数を増やすことなく容易に位置関係の調節
ができるという優れた効果がある。In particular, according to the image forming apparatus of the third aspect,
Since the outer peripheral surface of the position holding member is formed so that the outer diameter increases stepwise, the outer peripheral surface to be brought into contact with the latent image carrier is 1
By switching to the adjacent outer peripheral surface one by one, the positional relationship between the latent image carrier and the opposing member can be changed little by little,
There is an excellent effect that the positional relationship can be easily adjusted without increasing the number of special members.

【００５１】また、請求項４の画像形成装置によれば、
潜像担持体が傷ついて潜像担持体と対向部材との位置関
係が予期せずに変化してしまった場合でも、傷のない潜
像担持体表面に上記当接面を当接させて上記位置関係を
所望の位置関係にすることができるので、潜像担持体を
交換するのに比して低コスト化を図りつつ潜像担持体と
対向部材との位置関係を所望の位置関係に維持すること
ができるという優れた効果がある。According to the image forming apparatus of the fourth aspect,
Even if the latent image carrier is damaged and the positional relationship between the latent image carrier and the opposing member is unexpectedly changed, the contact surface is brought into contact with the surface of the latent image carrier having no damage. Since the positional relationship can be changed to a desired positional relationship, the positional relationship between the latent image carrier and the opposing member is maintained at a desired positional relationship while reducing costs as compared with replacing the latent image carrier. There is an excellent effect that can be.

【００５２】また、請求項５の画像形成装置によれば、
位置保持部材の軸部を左右逆にして装置内に取り付ける
という容易な操作で、傷のない潜像担持体表面部分に傷
のない当接面を当接させることができるので、潜像担持
体、又は位置保持部材を交換するのに比して低コストで
容易に潜像担持体と対向部材との位置関係を所望の位置
関係に維持することができるという優れた効果がある。According to the image forming apparatus of the fifth aspect,
With the easy operation of mounting the position holding member in the apparatus with the shaft part reversed left and right, the scratch-free contact surface can be brought into contact with the scratch-free latent image carrier surface portion. Alternatively, there is an excellent effect that the positional relationship between the latent image carrier and the opposing member can be easily maintained at a desired positional relationship at a lower cost than when the position holding member is replaced.

【００５３】請求項６の画像形成装置によれば、潜像担
持体と当接面との間に異物が入り込み当接面を傷つけて
現像ギャップが狂ってしまっても、位置保持部材を交換
することなく現像ギャップを所望の間隔に維持すること
ができるので、位置保持部材を交換するのに比して位置
保持部材のコストを低減しつつ現像ギャップを所望の間
隔に維持して、形成画像濃度を所望の濃度に維持できる
という優れた効果がある。上記現像ギャップを所望の間
隔に保つことは、１成分現像剤、２成分現像剤のどちら
を用いた画像形成装置でも、潜像担持体上の潜像に供給
される現像剤量が現像ギャップの影響を受けるものであ
れば必ず必要となるものである。しかしながら、もとも
と現像ギャップが大きく設定されている画像形成装置な
どでは現像ギャップのばらつきが画像濃度に及ぼす影響
が小さく、現像ギャップが小さく設定されている現像ギ
ャップのバラツキが画像濃度に及ぼす影響が大きい。本
発明の画像形成装置によれば、潜像担持体と当接面との
間への異物の混入によって発生する比較的小さい現像ギ
ャップの誤差をなくすことができるので、比較的現像ギ
ャップが小さく設定されている例えば１成分現像剤を用
いた画像形成装置などにおいても、現像ギャップを精度
良く所望の間隔に維持できるという優れた効果もある。
また、潜像担持体に当接する当接面が異なることによ
り、現像ギャップが異なるよう上記位置保持部材を形成
し、この位置保持部材を潜像担持体と現像剤担持体との
対向部における両端部即ち形成画像の両端部近傍に設け
れば、現像ギャップを形成画像の幅方向で所望の間隔に
設定することができ、該幅方向で現像ギャップがばらつ
いて該幅方向で画像濃度ムラが発生することを防止する
ことができるという優れた効果もある。また、更に、潜
像担持体に当接する当接面が異なることにより、現像ギ
ャップが異なるよう上記位置保持部材を形成すれば、潜
像担持体と現像剤担持体との対向部で、現像剤担持体上
の現像剤が現像電界により潜像に供給されるように構成
された画像形成装置において、装置の経時的使用によっ
て現像剤が劣化して画像濃度が薄くなるおそれがある場
合に、現像ギャップを初期設定値より小さくすることに
よって現像剤担持体上の現像剤に及ぶ現像電界の強度を
強くでき、画像濃度を回復させることができる。これに
より、現像剤寿命を延ばすことができ、画像形成装置の
ランニングコストが低減できるという優れた効果もあ
る。According to the image forming apparatus of the present invention, even if a foreign matter enters between the latent image carrier and the contact surface and damages the contact surface and the developing gap is deviated, the position holding member is replaced. Since the development gap can be maintained at a desired interval without the need for replacing the position holding member, the development gap can be maintained at the desired interval while the cost of the position holding member is reduced, and the formed image density can be maintained. Has an excellent effect that it can be maintained at a desired concentration. Maintaining the development gap at a desired interval requires that the amount of developer supplied to the latent image on the latent image carrier be equal to the development gap, even in an image forming apparatus using either one-component developer or two-component developer. If they are affected, they will always be needed. However, in an image forming apparatus or the like in which the developing gap is originally set to be large, the influence of the variation of the developing gap on the image density is small, and the variation of the developing gap in which the developing gap is set small has a large effect on the image density. According to the image forming apparatus of the present invention, it is possible to eliminate a relatively small developing gap error caused by foreign matter entering between the latent image carrier and the abutting surface. In an image forming apparatus using, for example, a one-component developer, there is also an excellent effect that the developing gap can be accurately maintained at a desired interval.
In addition, the position holding member is formed so that the developing gap is different due to the different contact surfaces that come into contact with the latent image carrier, and the position holding member is provided at both ends of the facing portion between the latent image carrier and the developer carrier. If the developing gap is provided in the vicinity of both ends of the formed image, the developing gap can be set at a desired interval in the width direction of the formed image, and the developing gap varies in the width direction to cause image density unevenness in the width direction. There is also an excellent effect that this can be prevented. Further, if the position holding member is formed so that the developing gap is different due to a different contact surface that comes into contact with the latent image carrier, the developer is provided at an opposing portion between the latent image carrier and the developer carrier. In an image forming apparatus configured so that a developer on a carrier is supplied to a latent image by a developing electric field, when the developer is deteriorated due to the use of the apparatus over time, the image density may be reduced. By making the gap smaller than the initial set value, the intensity of the developing electric field that reaches the developer on the developer carrier can be increased, and the image density can be restored. Thereby, there is also an excellent effect that the life of the developer can be extended and the running cost of the image forming apparatus can be reduced.

【図面の簡単な説明】[Brief description of the drawings]

【図１】本実施形態に係る画像形成装置における現像装
置近傍の概略構成図。FIG. 1 is a schematic configuration diagram near a developing device in an image forming apparatus according to an embodiment.

【図２】実施形態１にかかる位置保持部材を設けた現像
領域近傍の平面図。FIG. 2 is a plan view of the vicinity of a development area provided with the position holding member according to the first embodiment.

【図３】（ａ）は、実施形態２にかかる位置保持部材を
設けた現像領域近傍の平面図。（ｂ）は、実施形態２に
かかる位置保持部材を固設し直した説明図。FIG. 3A is a plan view of the vicinity of a developing area provided with a position holding member according to a second embodiment. FIG. 9B is an explanatory diagram in which the position holding member according to the second embodiment is fixed.

【符号の説明】[Explanation of symbols]

１ 感光体ドラム ２ 現像ローラ ３ 薄層化ブレード ４ 供給ローラ ５ａ，５ｂ トナー撹拌部材 ６ トナーホッパ １０ａ、１０ｂ、１３ａ、１３ｂ 位置保持部材 Reference Signs List 1 photosensitive drum 2 developing roller 3 thinning blade 4 supply roller 5a, 5b toner stirring member 6 toner hopper 10a, 10b, 13a, 13b position holding member

Claims (6)

【特許請求の範囲】[Claims] 【請求項１】表面に潜像を担持する潜像担持体と、該潜
像担持体に対向して設けられる対向部材と、該潜像担持
体と該対向部材との位置関係が所定の位置関係になるよ
う該潜像担持体に対する該対向部材の位置を決める位置
決め手段とを有する画像形成装置において、 上記位置決め手段を、それぞれ単独で上記潜像担持体に
当接可能な複数の当接面を有する位置保持部材と、上記
潜像担持体に当接する上記当接面を切り替える当接面切
り替え手段とから構成したことを特徴とする画像形成装
置。A latent image carrier for carrying a latent image on a surface thereof; an opposing member provided to face the latent image carrier; and a positional relationship between the latent image carrier and the opposing member being a predetermined position. An image forming apparatus having positioning means for determining the position of the opposing member with respect to the latent image carrier in a relationship, wherein the positioning means comprises a plurality of contact surfaces each of which can independently contact the latent image carrier. An image forming apparatus comprising: a position holding member having: a contact surface switching unit that switches the contact surface that contacts the latent image carrier. 【請求項２】請求項１の画像形成装置において、前記潜
像担持体に当接する前記当接面が異なることにより、潜
像担持体表面と上記対向部材との位置関係が異なるよう
上記位置保持部材を形成したことを特徴とする画像形成
装置。2. The image forming apparatus according to claim 1, wherein said contact surface which contacts said latent image carrier is different, so that said positional holding is performed such that the positional relationship between said latent image carrier surface and said opposing member is different. An image forming apparatus comprising a member. 【請求項３】請求項２の画像形成装置において、前記位
置保持部材の前記複数の当接面を、段階的に外径が大き
くなる複数の外周面で形成したことを特徴とする画像形
成装置。3. An image forming apparatus according to claim 2, wherein said plurality of contact surfaces of said position holding member are formed by a plurality of outer peripheral surfaces whose outer diameters gradually increase. . 【請求項４】請求項１の画像形成装置において、前記複
数の当接面が、上記潜像担持体のそれぞれ異なる位置に
当接するよう前記位置保持部材及び当接面切り替え手段
を構成したことを特徴とする画像形成装置。4. The image forming apparatus according to claim 1, wherein the position holding member and the contact surface switching means are configured so that the plurality of contact surfaces contact different positions of the latent image carrier. Characteristic image forming apparatus. 【請求項５】請求項４の画像形成装置において、前記位
置保持部材を、該画像形成装置の前記潜像担持体表面か
ら所定距離離間した位置に取り付け可能な軸部と、該軸
部に設けられ、該軸部を上記画像形成装置に取り付ける
方向を正又は逆方向で変えることにより上記潜像担持体
に当接する上記当接面が入れ替わる当接面をそれぞれ有
する２つの凸部とから構成したことを特徴とする画像形
成装置。5. An image forming apparatus according to claim 4, wherein said position holding member is provided on a shaft portion mountable at a position separated by a predetermined distance from a surface of said latent image carrier of said image forming device. And two convex portions each having an abutting surface where the abutting surface that abuts on the latent image carrier is changed by changing the direction in which the shaft portion is attached to the image forming apparatus in the forward or reverse direction. An image forming apparatus comprising: 【請求項６】請求項１、２、３、４又は５の画像形成装
置において、該潜像担持体上の潜像を現像するための現
像剤を表面に担持する現像剤担持体を有し、前記位置決
め手段により前記潜像担持体表面と上記現像剤担持体表
面との間の間隔を所定の間隔に保つよう該潜像担持体に
対する該現像剤担持体の位置を決めることを特徴とする
画像形成装置。6. The image forming apparatus according to claim 1, further comprising a developer carrying member for carrying a developer for developing a latent image on said latent image carrying member on a surface thereof. Wherein the position of the developer carrier with respect to the latent image carrier is determined by the positioning means so as to maintain a predetermined distance between the surface of the latent image carrier and the surface of the developer carrier. Image forming device.