JP2004094097A - Apparatus and method for forming image - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an apparatus and a method for forming an image, capable of cleaning the residual toner on the surface of an image carrier without a cleaning failure. <P>SOLUTION: In the apparatus of forming the image having an elastic blade 41 which is brought into contact with the surface of a photosensitive drum 1 to be rotated and cleans the residual toner on the surface of the photosensitive drum 1, it is constituted so that the elastic blade 41 is vibrated in the case of contact cleaning of the photosensitive drum 1 and frequency f of vibration satisfies a relation expression f≥P/n by defining rotation speed of the photosensitive drum as P and defining nip width as a contact between the photosensitive drum 1 and the elastic blade 41 as n. <P>COPYRIGHT: (C)2004,JPO

Description

【００８３】
以上の結果から、反発弾性率が２５となる環境温度４２℃の時に、ブレード振動周波数は上記関係式を満たす。この時の捕集量は０．０１［ｇ］であった。このため、本画像形成装置に於いては、画像設計時に４２℃を保つことが不可欠である。ここで、図１に、本発明に係る画像形成装置の第１の実施形態で使用しているクリーニングブレードの反発弾性率の温度特性のグラフを示す。図１において、縦軸は反発弾性率（％）、横軸はドラムヒーター温調温度（℃）である。
【００８４】
本実施形態に於いての必要環境温度は上記のごとくであるが、その他の画像形成装置により最適な構成とは、前記関係式を満たす構成により達成される。
【００８５】
このように、本発明に係る画像形成装置の第１の実施形態では、クリーニングブレードの反発弾性率が所定の値となるように画像形成装置の温度を調整し、その結果、前記関係式ｆ≧Ｐ／ｎを満たすようにしているため、画像形成装置のクリーニング性能の低下を防ぐことができる。なお、関係式ｆ≧Ｐ／ｎを満たすため、温度以外の他の各部材や環境を設定するとしても良い。
【００８６】
（第２の実施形態）
次に、本発明に係る画像形成装置の第２の実施形態について図面を参照して説明する。なお、本実施形態の画像形成装置の全体構成は、前述の従来技術の説明における図４と略同様であるため、その詳細な説明は省略し、適宜図４を用いて説明を行う。また、図２に、本発明に係る画像形成装置の第２の実施形態において使用されるクリーニング装置の拡大図を示す。
【００８７】
図２において、クリーニングブレード４１は導電性を有し、交流印加装置５０により所定の周波数を持った交流電流が印加されている。
【００８８】
クリーニングブレード４１は、ブレードホルダ４３と加圧バネ４４によって、設定角を３０°、長手方向長さ１ｃｍ当たり２０ｇの荷重（２０ｇ／ｃｍ）で感光ドラム１に当接されている。今像担持体たる感光ドラム１は周速５００ｍｍ／秒で回転駆動される。
【００８９】
この時のクリーニングブレード４１と感光ドラム１の当接状態を拡大した状態は、従来例と同じく図６に示される。
【００９０】
図６の（ａ）、（ｂ）、（ｃ）の状態については、スティック−スリップ運動の状態をそれぞれ示し、ここで（ａ）−（ｃ）間での一連の動きを一単位として、基準時間内の繰り返し回数を振動数：ｆとする。
【００９１】
また、図６の（ａ）において、感光ドラム１は図中右から左に回転しておりその速度Ｐが前記より速度５００ｍｍ／ｓｅｃとなる。上記当接条件（荷重・設定角）に於いて、クリーニングブレード４１の感光ドラム１への当接ニップ幅ｎは、平均１０μｍであった。
【００９２】
また、本実施形態においても、前述の第１の実施形態と同様に、スティック−スリップ運動の関係式ｆ≧Ｐ／ｎを用いる。
【００９３】
この関係式を用いると、この系に於いてスティック−スリップ運動は、５０ｋＨｚ以上必要である。
【００９４】
そこで本実施形態に於いては、上記スティック−スリップ運動の振動数関係式の結果から、交流印加装置５０によってクリーニングブレード４１にｆ＝５０ｋＨｚの交流電流を印加する構成とした。
【００９５】
これにより、低温低湿環境から、高温高湿環境の環境条件によらず、安定したクリーニング性能を得るに至った。
【００９６】
本実施形態に於いての交流電流周波数は上記のごとくであるが、その他の画像形成装置（像担持体・クリーニングブレード材質・当接条件など）により、かかる交流電流の周波数は最適化するのは言うまでもない。
【００９７】
このように、本実施形態においても、関係式ｆ≧Ｐ／ｎを満たすようにクリーニングブレード４１に交流電流を印加しているため、前述の第１の実施形態と同様の効果を得ることができる。
【００９８】
（第３の実施形態）
次に、本発明に係る画像形成装置の第３の実施形態について説明する。なお、本第３の実施形態においても、前述の図４に示される画像形成装置の構成の説明が成り立つ。
【００９９】
前述の第２の実施形態によりブレードニップ部の動きを、スティック−スリップ運動の振動周波数関係式から導かれる、周波数以上の交流電流を印加することにより、低温低湿環境から、高温高湿環境の環境条件によらず、安定したクリーニング性能を得るに至った。
【０１００】
本実施形態では、印加する交流に加え、不図示の直流印加装置により、像担持体の残存電位分の直流電位を印加することにより、帯電前露光を廃しさらなるコストダウンを達成できる、クリーニング同時帯電前除電装置を提供する。
【０１０１】
従来例の如く、像担持体は帯電・現像・転写を経て、クリーニング過程、帯電前除電（露光）に至る。それらの過程で像担持体の表面電位は、各工程位置に於いて図７の如く推移する。図７は、従来の画像形成装置における、各工程位置での像担持体表面電位のグラフである。図７において、縦軸は像担持体平均表面電位（Ｖ）、横軸は各工程位置を示す。
【０１０２】
グラフ中Ｘ軸Ｏは、前形成行程の前露光であり、以下帯電・現像・転写・クリーニング・前露光とそれぞれの位置で像担持体たる感光ドラム１の表面電位を測定した平均値である。なお、帯電から次形成帯電までが感光ドラム一回転分となる。
【０１０３】
図７に示される転写の時点で、４００Ｖに帯電された感光ドラム１は５０Ｖ迄電位が落ち、以降前露光により除電されるまで減衰しづらい残存電位となる。
【０１０４】
ここで、本発明にかかる清掃装置を用いることにより電位の推移は図３の如く変化する。図３は、本発明に係る画像形成装置の第３の実施形態における、各工程位置での像担持体表面電位のグラフである。図３において、縦軸は像担持体平均表面電位（Ｖ）、横軸は各工程位置を示す。
【０１０５】
この系らにおけるブレードに印加する直流電位は、測定値より−５０Ｖとした。これにより、図３のグラフ中円で囲んだ通りクリーナー位置で残存電位を除電する事が可能となった。
【０１０６】
グラフには測定位置として便宜上、前露光位置を表記しているが、装置構成上本第２の実施形態にかかる画像形成装置では、前露光を廃した構成としている。
【０１０７】
以上のように、本実施形態では、容易に周波数を制御できる構成の清掃装置において、像担持体表面の残存電位分の直流電位を印加することにより、前露光を廃し、コストダウンを図り安定したクリーニング性能を発揮する清掃装置を提供できるに至った。
【０１０８】
【発明の効果】
以上のように、本発明にかかる画像形成装置によれば、回転する像担持体の表面に接し、該像担持体の表面の残留トナーをクリーニングするクリーニング手段を備えた画像形成装置において、像担持体接触清掃時のクリーニング手段は振動し、その周波数：ｆは、像担持体回転速度：Ｐ、像担持体と前記クリーニング手段の接点であるニップ幅：ｎとして、ニップを通過する像担持体の移動量に着目し、ｆ≧Ｐ／ｎの関係となるように、像担持体と清掃装置の侵入量、設定角、反発弾性率等の設計項目を構成することにより、最適なクリーニング能力を得ることが可能となる。
【０１０９】
また、所定の振動数を得るため反発弾性率を選択してクリーニング手段を使用することにより、安定した清掃装置を提供できるに至った。
【０１１０】
また、回転する像担持体の表面に接し、該像担持体の表面の残留トナーをクリーニングするクリーニング手段を備えた画像形成装置において、像担持体接触清掃時のクリーニング手段は駆動し、その周波数：ｆは、像担持体回転速度：Ｐ、像担持体とクリーニング手段との接点であるニップ幅：ｎとして、ニップを通過する像担持体の移動量に着目し、ｆ≧Ｐ／ｎの関係となるように、クリーニング手段の振動を制御する制御手段を有することで、低温低湿環境から、高温高湿環境の環境条件によらず、安定したクリーニング性能を得るに至った。
【０１１１】
また、振動を制御する制御手段として、交流電流を印加する印加手段を用いたことで、容易に周波数を制御できる構成で、安定した清掃装置を提供できるに至った。
【０１１２】
さらに、交流電流に像担持体の残存電位に対応する直流電位を印加する直流印加手段を備えることで、清掃同時除電を可能とする清掃装置とし、前露光を廃しコストダウンを図り、高いクリーニング性能を有する安定した清掃装置を提供するに至った。
【図面の簡単な説明】
【図１】本発明に係る画像形成装置の第１の実施形態で使用しているクリーニングブレードの反発弾性率の温度特性のグラフを示す。
【図２】本発明に係る画像形成装置の第２の実施形態において使用されるクリーニング装置の拡大図を示す。
【図３】本発明に係る画像形成装置の第３の実施形態における、各工程位置での像担持体表面電位のグラフである。
【図４】従来例に係る画像形成装置の形態を示す構成図である。
【図５】図４に示されるクリーニング装置１３の拡大図である。
【図６】従来の画像形成装置における感光ドラムに接するブレードニップ部における挙動を示す模式図である。
【図７】従来の画像形成装置における、各工程位置での像担持体表面電位のグラフである。
【符号の説明】
１　感光ドラム
４０　トナー
４１　クリーニングブレード
４２　磁気ブラシローラ
４３ブレードホルダ
４４　加圧バネ
５０　交流印加装置[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an image forming apparatus and an image forming method for forming an image on a recording medium by an electrophotographic method.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, an image forming apparatus that forms an image by electrophotography has been used for devices such as a laser printer and a digital copy.
[0003]
FIG. 4 is a configuration diagram illustrating a form of an image forming apparatus according to a conventional example. Here, the conventional configuration is described using a digital copier.
[0004]
In FIG. 4, a reader unit 18 irradiates the original 15 placed on the original glass table 14 with light from an illumination lamp 16 and forms the reflected light on a one-line CCD 19 of a photoelectric conversion element to form image information. Convert to the corresponding electrical signal.
[0005]
Here, the reflected light from the original 15 illuminated by the illumination lamp 16 is guided to mirrors 17a, 17b, and 17c and is imaged on the photoelectric conversion element 19 by the lens 17d.
[0006]
The electric signal output by the photoelectric conversion element 19 is subjected to A / D conversion by the A / D converter 21 to become 8-bit digital image data, and thereafter, the black signal generation circuit 22 converts the luminance information into density information. Is converted to image density data.
[0007]
The 8-bit digital image data signal generated as described above is input to the laser drive circuit 24. The laser drive circuit 24 is a well-known PWM circuit and controls the emission time of the semiconductor laser 20 according to the magnitude of the input image density signal.
[0008]
The image forming unit includes a photosensitive drum 1 as an image carrier, and the photosensitive drum 1 is provided with a photoconductive layer on or around a conductive support such as an aluminum drum installed on the inner peripheral side as is well known. , And rotates in the direction of the arrow in FIG.
[0009]
Around the photosensitive drum 1, a charging device 2, a developing device 7, a pre-transfer charging device 5, a transfer charging device 8, an electrostatic separation charging device 9, a cleaning device 13, and the like are sequentially arranged.
[0010]
In the illustrated example, the charging device 2 is a scorotron charger, which primarily charges the surface of the photosensitive drum 1 to a uniform charge. An electrostatic latent image is formed on the photosensitive drum 1 by exposure 3 from an exposure unit on the downstream side of the charging device 2 in the drum rotation direction.
[0011]
The charging device 2 uniformly charges the surface of the rotating photosensitive drum 2 moving in the sub-scanning direction to a potential of about 400 (V) by corona discharge. In the exposure 3, the surface of the charged photosensitive drum 2 is exposed by two laser beams deflected and scanned in the main scanning direction, and is discharged at a potential of about 50 (V).
[0012]
This electrostatic latent image is developed by the developing device 7. The developing device 7 is provided with a developing roller having a magnetic field generating means inside. The developing roller frictionally charges the developer toner stored inside and develops an electrostatic latent image on the surface of the photosensitive drum 1. A toner is supplied to the electrostatic latent image, and the electrostatic latent image is developed to be visualized as a toner image.
[0013]
The toner is a one-component magnetic toner (styrene-acrylic toner) and has a volume resistance of 10%. ⁶ -10 ¹² Ωcm, the critical surface tension is about 35 dyn / cm. Incidentally, the critical surface tension of the surface of the photosensitive drum 1 is 40 to 45 dyn / cm.
[0014]
The developed electrostatic image on the photosensitive drum 1 is transferred by a pre-transfer charger 5 and a transfer charger (corona transfer charger) 8 onto transfer paper P, which is a transfer material conveyed by a transfer guide or the like. You.
[0015]
The transfer paper P on which the toner image has been transferred is separated from the photosensitive drum 1 by an electrostatic separation charging device (separation charging device) 9.
[0016]
The electrostatic separation charging device (separation charging device) 9 uses a corona discharge to transfer the toner image from the photosensitive drum 1 to the transfer paper P and transfer the toner image to the transfer paper P from the photosensitive drum 1. It helps with separation.
[0017]
Here, the polarity of the corona discharge used in the transfer charger (corona transfer charger) 8 is opposite to that of the toner, and the polarity of the corona discharge used in the electrostatic separation charger (separation charger) 9 is the same as the toner. It is.
[0018]
The transfer paper P on which the toner image is transferred is conveyed to the fixing device 12 after being separated from the photosensitive drum 1, where the toner image on the surface is fixed, and a desired print image is formed. Is discharged.
[0019]
On the other hand, the residual toner after the transfer process exists on the photosensitive drum 1 after the transfer of the toner image, and the residual toner is removed by the cleaning device 13.
[0020]
Here, the cleaning device shown in FIG. 4 will be described with reference to FIG. FIG. 5 is an enlarged view of the cleaning device 13 shown in FIG.
[0021]
A cleaning assisting device for peeling off the residual toner from the photosensitive drum 1 by a magnetic (magnet) roller 42 and uniformly reapplying the same to the photosensitive drum 1, and a cleaning blade 41 for scraping the uniformly reapplied residual toner from above the photosensitive drum 1 It consists of a main cleaning device to be dropped. However, this is not always the case depending on the image forming apparatus.
[0022]
The cleaning blade 41 is fixed and supported by the blade holder 43, and comes into contact with the photosensitive drum 1 under the conditions of the penetration amount δ and the set angle θ. However, this is not always the case depending on the image forming apparatus.
[0023]
The photosensitive drum 1 from which the residual toner has been scraped off by the cleaning device is subjected to pre-exposure (lamp) 30 to remove the residual charge, and is ready for the next image formation.
[0024]
In an image forming method using such an image forming apparatus, an image is generally formed by binary dots by turning on and off a laser beam in accordance with print data as described above.
[0025]
As described above, even when the dots of the image are expressed in binary, the image can be expressed in gradation by using the error diffusion method or the dither method that expresses the density with a plurality of dots.
[0026]
Conventionally, organic compound photoreceptors are generally used for the photosensitive layer on the surface of the photosensitive drum of the above-described image forming apparatus. As described above, a photosensitive member mainly composed of amorphous silicon used in a high-speed analog copying machine is used.
[0027]
The potential distribution of the electrostatic latent image formed by the exposure of the amorphous silicon photoconductor is closer to the intensity distribution of the laser beam than the organic compound photoconductor.
[0028]
Therefore, when the amorphous silicon photoreceptor is used for the surface layer of the photosensitive drum, the electrostatic latent image is sharply formed, and fine lines in the main scanning direction can be reproduced well.
[0029]
At present, the image exposure apparatus has two laser light sources, and simultaneously exposes two main scanning lines to one photosensitive drum with two laser beams arranged in the sub-scanning direction, thereby improving image resolution. Some products have improved formation rates without reduction.
[0030]
Meanwhile, the photosensitive drum 1 in the conventional example has an amorphous silicon photosensitive layer having a thickness of 30 μm formed by glow discharge or the like on an aluminum cylinder having a diameter of 108 mm and a thickness of about 5 mm.
[0031]
The amorphous silicon photosensitive layer is worn by rubbing of the magnetic brush roller, contact of the cleaning blade, etc., and the wear depends on the amount of toner in each rubbing / contact portion. Inside the photosensitive drum 1, a not-shown planar heating element heater (not shown) of about 80 W is arranged for one round, and the electric power is controlled so that the temperature of the aluminum cylinder becomes 42 ° C.
[0032]
As described above, the configuration of the cleaning member of the photosensitive drum 1 differs depending on the image forming apparatus. However, many image forming apparatuses currently use a cleaning blade made of polyurethane rubber having elasticity.
[0033]
Further, as the image carrier, there are a transfer device, an intermediate transfer member, and the like, and many configurations using a blade as a cleaning device have been proposed.
[0034]
For this reason, the analysis of the mechanism of cleaning the image carrier and the blade has been actively conducted, and the behavior of the cleaning blade in contact with the surface of the image carrier is a repetition of stick (fixation) -slip (returns to the original state while slipping: slip motion). It is well known that you are exercising.
[0035]
The behavior of the blade nip in contact with the photoconductor will be briefly described with reference to the schematic diagram shown in FIG. FIG. 6 is a schematic diagram showing a behavior in a blade nip portion in contact with a photosensitive drum in a conventional image forming apparatus.
[0036]
When the blade is sticked (fixed) to the surface of the photoconductor, the blade nip is extended in the rotation direction of the photoconductor 1 ((a) → (b) in FIG. 6: stick state).
[0037]
When the blade nip is extended, the repulsive force of the cleaning blade 41 increases, and when the static friction force and the repulsive force are balanced, the blade nip slides on the photoreceptor surface (relative slip occurs).
[0038]
When the blade nip slides between the photoreceptor surface and the dynamic friction coefficient is smaller than the static friction coefficient, the blade nip returns to the original position of the blade nip while sliding on the photoreceptor surface (FIG. 6 (b) → (c): Slip movement).
[0039]
The cleaning blade 41 scrapes off the transfer residual toner from the surface of the photosensitive drum 1 while continuously repeating the stick-slip movement.
[0040]
It is well known that the behavior of the blade nip in other image carriers is basically the same, although the dynamic friction coefficient and the sexual friction coefficient are different.
[0041]
The state of the stick-slip motion includes the material of the surface of the image carrier (photosensitive drum 1) and the cleaning blade 41, the nip width of the image carrier (photosensitive drum 1) and the cleaning blade 41, the rotation speed of the image carrier, and the blade. Depends on temperature characteristics.
[0042]
The cleaning failure such as slip-through is more likely to occur if the stick-slip motion is abnormal.
[0043]
For example, in the process of the stick-slip movement, if substances other than toner and external additives such as paper powder are caught between the blade and the surface of the image carrier, cleaning failure such as slip-through occurs.
[0044]
Further, when the cleaning blade and the surface of the image carrier are worn by friction between each other, and the blade nip state is different from the initial condition, the cycle of the stick-slip movement is changed, and the cleaning ability is reduced, and the photosensitive drum torque is increased. There is a problem that leads to defects such as blade chatter and curling.
[0045]
In order to solve such a problem, Japanese Patent Application Laid-Open No. H11-223977 proposes an invention in which a foreign substance is removed by reverse rotation of a photoreceptor in a state in which a toner or paper dust is caught.
[0046]
Japanese Patent Application Laid-Open No. 5-188832 has proposed an invention in which a conductive lubricant is applied to the surface of a blade, and a voltage is applied to the blade as an electrode to stabilize the cleaning ability by vibrating slightly.
[0047]
[Problems to be solved by the invention]
However, in the case of the above-described conventional technology, the following problems have occurred. In the conventional image forming apparatus configuration as described above, it is necessary to complicate the configuration of the cleaning apparatus, and it is necessary to install a power supply for the cleaning apparatus. It is not applicable to the configuration.
[0048]
Further, the conventional image forming apparatus regulates the electric resistance of the blade in order to maintain the desired charging performance, and the contact pressure of the blade with the photoconductor in order to maintain the cleaning performance, and the particle diameter of the developer. Although the number ratio and the edge angle of the blade with respect to the photoreceptor are specified, the residual toner remaining on the photoreceptor cannot be completely removed by the blade, and some toner slips through the blade. It was easy.
[0049]
Further, when the operating temperature at which a predetermined rebound resilience is obtained is set so that the frequency of the stick-slip motion satisfies a predetermined relational expression, in an image forming apparatus used in various environments, Implementation may be costly.
[0050]
Further, depending on the material of the blade, the blade nip width is not stable, and it is difficult to stably obtain vibration of the blade even with a predetermined configuration and temperature.
[0051]
The present invention has been made in view of the above problems, and has as its object to provide an image forming apparatus and an image forming method capable of cleaning residual toner on the surface of an image carrier without cleaning failure. .
[0052]
[Means for Solving the Problems]
In order to achieve the above object, an image forming apparatus according to the present invention is an image forming apparatus comprising: a cleaning unit that contacts a surface of a rotating image carrier and cleans residual toner on the surface of the image carrier. The cleaning means vibrates at the time of contact cleaning of the image carrier, and the frequency f of the vibration is represented by a relational expression, where P is the rotation speed of the image carrier, and n is a nip width which is a contact point between the image carrier and the cleaning means. , F ≧ P / n.
[0053]
Further, in the image forming apparatus according to the present invention, the relational expression is satisfied by setting the temperature of the cleaning unit such that the cleaning unit has a predetermined resilience.
[0054]
In the image forming apparatus according to the present invention, the cleaning unit is an elastic blade.
[0055]
Further, the image forming apparatus according to the present invention includes a control unit that controls the vibration of the cleaning unit at the time of cleaning the contact with the image carrier in order to satisfy the relational expression.
[0056]
Further, in the image forming apparatus according to the present invention, the control unit includes an application unit that applies an alternating current having a predetermined frequency determined from the relational expression to the cleaning unit.
[0057]
Further, in the image forming apparatus according to the present invention, when the control unit controls the vibration of the cleaning unit at the time of cleaning the contact with the image carrier, the control unit controls the cleaning unit to apply a DC voltage to cancel a residual potential of the image carrier. DC applying means for applying a potential.
[0058]
Further, the image forming method according to the present invention is the image forming method in an image forming apparatus provided with a cleaning unit that contacts a surface of the rotating image carrier and cleans residual toner on the surface of the image carrier. The cleaning unit vibrates at the time of body contact cleaning, and the frequency f of the vibration is represented by P, the rotational speed of the image carrier is represented by P, and the nip width which is a contact point between the image carrier and the cleaning unit is represented by n. An image is formed with a configuration satisfying ≧ P / n.
[0059]
In the image forming method according to the present invention, the relational expression is satisfied by setting the temperature of the cleaning unit such that the cleaning unit has a predetermined rebound resilience.
[0060]
In the image forming method according to the present invention, the cleaning unit is an elastic blade.
[0061]
Further, the image forming method according to the present invention includes a step of controlling the vibration of the cleaning unit at the time of cleaning the contact of the image carrier, in order to satisfy the relational expression.
[0062]
Further, the image forming method according to the present invention includes a step in which the application unit provided in the control unit applies an alternating current having a predetermined frequency determined from the relational expression to the cleaning unit.
[0063]
Further, in the image forming method according to the present invention, when the DC application means provided in the control means controls the vibration of the cleaning means at the time of contact cleaning of the image carrier, the cleaning means includes: A step of applying a DC potential for canceling the residual potential.
[0064]
As described above, according to the present invention, in the image forming apparatus including the cleaning unit that contacts the surface of the rotating image carrier and cleans residual toner on the surface of the image carrier, the cleaning unit at the time of contact cleaning of the image carrier is provided. Focuses on the amount of movement of the image carrier passing through the nip, assuming that the frequency: f is the image carrier rotation speed: P, and the nip width: n, which is the contact point between the image carrier and the elastic blade, is f Since the design items such as the amount of penetration of the image carrier and the cleaning device, the set angle, the rebound resilience, and the like are configured so as to satisfy the relationship of ≧ P / n, the cleaning performance can be improved.
[0065]
Further, the present invention is characterized in that a rebound resilience satisfying the above equation is selected and a cleaning unit is used.
[0066]
Further, the present invention is characterized by having a control means for controlling the vibration of the cleaning means so as to satisfy the relation of f ≧ P / n, so that the cleaning means can be stabilized irrespective of the environmental conditions (temperature / humidity) and the device configuration. The cleaning ability can be demonstrated.
[0067]
Further, in the present invention, as a method of controlling the cleaning unit, an AC current having a predetermined frequency is applied, and the cleaning unit vibrates at the frequency of the AC current, so that a desired cleaning ability can be obtained. become.
[0068]
Further, in the present invention, by applying a DC potential for canceling the residual potential of the image carrier to an AC current for controlling the vibration of the cleaning unit, it is possible to simultaneously perform the cleaning and neutralization.
[0069]
BEST MODE FOR CARRYING OUT THE INVENTION
Preferred embodiments of the present invention will be illustratively described in detail below with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention thereto unless otherwise specified. Absent.
[0070]
In the following drawings, the same reference numerals are given to components described in the drawings used in the above description of the related art and components similar to the components described in the drawings described above. The description of each embodiment of the image forming apparatus according to the present invention described below also serves as the description of each embodiment of the image forming method according to the present invention.
[0071]
(1st Embodiment)
Hereinafter, a first embodiment of an image forming apparatus according to the present invention will be described in detail with reference to the drawings. Since the configuration of the first embodiment of the image forming apparatus according to the present invention is the same as the configuration of the conventional image forming apparatus described with reference to FIGS. 4 and 5 described above, FIGS. 5, and a detailed description thereof will be omitted.
[0072]
The cleaning blade 41 is in contact with the photosensitive drum 1 by a blade holder 43 and a pressure spring 44 shown in FIG. 5 at a set angle of 30 ° and a load of 20 g / cm (20 g / cm) in the longitudinal direction. The photosensitive drum 1 is driven to rotate at a peripheral speed of 500 mm / sec.
[0073]
The enlarged view of the contact state between the cleaning blade 41 and the photosensitive drum 1 at this time is the same as that in FIG. 6 described above.
[0074]
6A, 6B, and 6C show stick-slip motions, respectively, as in the description of the conventional example.
[0075]
Here, a series of movements between the states shown in (a), (b), and (c) of FIG.
[0076]
Also, in FIG. 6A, the photosensitive drum 1 is rotating from right to left in the figure, and its speed P becomes 500 mm / sec.
[0077]
Under the contact conditions (load and set angle), the contact nip width n of the cleaning blade 41 to the photosensitive drum 1 was 10 μm on average.
[0078]
Here, in the present embodiment, each member and environment are set so as to satisfy the relationship of the relational expression f ≧ P / n.
[0079]
Using the above relational expression, the stick-slip motion in this system requires 50 kHz or more. The effect is confirmed below.
[0080]
(Confirmation experiment)
The following confirmation experiments were performed to confirm the effects of the above invention.
"conditions"
Using a cleaning blade, the cleaning performance at an operating temperature of 10 ° C. and a cleaning performance at 42 ° C. are compared under the above-described conditions of the image carrier rotation speed, load, and set angle. However, the humidity kept a constant value.
[0081]
"Confirmation details"
The solid image is directly sent to the cleaning member for one minute by the idle rotation tester, and then is rotated idle for three minutes. Downstream of the cleaning blade, the toner passing through is collected, and its amount is compared after a total of 4 minutes of rotation.
[0082]
"Check result"
The results are shown in the table below.
[Table 1]

[0083]
From the above results, the blade vibration frequency satisfies the above relational expression when the environmental temperature is 42 ° C. where the resilience is 25. The collected amount at this time was 0.01 [g]. For this reason, in the present image forming apparatus, it is indispensable to keep the temperature at 42 ° C. when designing the image. Here, FIG. 1 shows a graph of the temperature characteristics of the rebound resilience of the cleaning blade used in the first embodiment of the image forming apparatus according to the present invention. In FIG. 1, the vertical axis represents the rebound resilience (%), and the horizontal axis represents the drum heater temperature control temperature (° C.).
[0084]
Although the required environmental temperature in the present embodiment is as described above, an optimum configuration for other image forming apparatuses is achieved by a configuration that satisfies the above relational expression.
[0085]
As described above, in the first embodiment of the image forming apparatus according to the present invention, the temperature of the image forming apparatus is adjusted such that the resilience of the cleaning blade becomes a predetermined value. As a result, the relational expression f ≧ Since P / n is satisfied, it is possible to prevent a decrease in the cleaning performance of the image forming apparatus. In order to satisfy the relational expression f ≧ P / n, other members and environments other than the temperature may be set.
[0086]
(Second embodiment)
Next, a second embodiment of the image forming apparatus according to the present invention will be described with reference to the drawings. Note that the overall configuration of the image forming apparatus according to the present embodiment is substantially the same as that of FIG. 4 in the description of the related art described above, and thus a detailed description thereof will be omitted, and description will be made with reference to FIG. FIG. 2 is an enlarged view of a cleaning device used in the second embodiment of the image forming apparatus according to the present invention.
[0087]
In FIG. 2, the cleaning blade 41 has conductivity, and an AC current having a predetermined frequency is applied by an AC applying device 50.
[0088]
The cleaning blade 41 is in contact with the photosensitive drum 1 by a blade holder 43 and a pressure spring 44 at a set angle of 30 ° and a load of 20 g / cm (20 g / cm) in the longitudinal direction. The photosensitive drum 1, which is now an image carrier, is rotated at a peripheral speed of 500 mm / sec.
[0089]
FIG. 6 shows an enlarged state of the contact between the cleaning blade 41 and the photosensitive drum 1 at this time, similarly to the conventional example.
[0090]
6A, 6B, and 6C show the states of the stick-slip motion, respectively, where a series of movements between (a) and (c) is defined as one unit. The number of repetitions within the time is defined as a frequency: f.
[0091]
In FIG. 6A, the photosensitive drum 1 is rotating from right to left in the figure, and the speed P is 500 mm / sec. Under the contact conditions (load and set angle), the contact nip width n of the cleaning blade 41 to the photosensitive drum 1 was 10 μm on average.
[0092]
Also in the present embodiment, the stick-slip motion relational expression f ≧ P / n is used, as in the first embodiment.
[0093]
Using this relationship, the stick-slip motion in this system requires 50 kHz or more.
[0094]
Therefore, in the present embodiment, from the result of the frequency relational expression of the stick-slip motion, an AC current of f = 50 kHz is applied to the cleaning blade 41 by the AC applying device 50.
[0095]
As a result, stable cleaning performance has been obtained irrespective of environmental conditions such as a low temperature and low humidity environment and a high temperature and high humidity environment.
[0096]
Although the alternating current frequency in the present embodiment is as described above, the frequency of the alternating current is optimized by other image forming apparatuses (image carrier, cleaning blade material, contact conditions, etc.). Needless to say.
[0097]
As described above, also in the present embodiment, since the alternating current is applied to the cleaning blade 41 so as to satisfy the relational expression f ≧ P / n, the same effect as that of the first embodiment can be obtained. .
[0098]
(Third embodiment)
Next, a third embodiment of the image forming apparatus according to the present invention will be described. Note that the description of the configuration of the image forming apparatus shown in FIG. 4 described above also holds in the third embodiment.
[0099]
According to the above-described second embodiment, the movement of the blade nip is changed from a low-temperature low-humidity environment to a high-temperature high-humidity environment by applying an alternating current having a frequency or more derived from the vibration frequency relational expression of the stick-slip motion. Irrespective of the conditions, stable cleaning performance was obtained.
[0100]
In this embodiment, in addition to the applied AC, a DC application device (not shown) applies a DC potential corresponding to the remaining potential of the image carrier, thereby eliminating pre-charging exposure and achieving further cost reduction. A pre-static elimination device is provided.
[0101]
As in the conventional example, the image carrier undergoes charging, development, and transfer, followed by a cleaning process and a pre-charging charge removal (exposure). In these processes, the surface potential of the image carrier changes as shown in FIG. 7 at each process position. FIG. 7 is a graph of an image carrier surface potential at each process position in a conventional image forming apparatus. In FIG. 7, the vertical axis represents the average surface potential (V) of the image carrier, and the horizontal axis represents each process position.
[0102]
In the graph, the X-axis O represents the pre-exposure in the pre-forming process, and is an average value obtained by measuring the surface potential of the photosensitive drum 1 serving as an image carrier at each position of charging, development, transfer, cleaning and pre-exposure. Note that the period from the charging to the next forming charging is equivalent to one rotation of the photosensitive drum.
[0103]
At the time of the transfer shown in FIG. 7, the potential of the photosensitive drum 1 charged to 400 V drops to 50 V, and thereafter becomes a residual potential that is hardly attenuated until the charge is removed by pre-exposure.
[0104]
Here, the transition of the potential changes as shown in FIG. 3 by using the cleaning device according to the present invention. FIG. 3 is a graph of an image carrier surface potential at each process position in the third embodiment of the image forming apparatus according to the present invention. In FIG. 3, the vertical axis indicates the average surface potential (V) of the image carrier, and the horizontal axis indicates each process position.
[0105]
The DC potential applied to the blade in this system was -50 V from the measured value. This makes it possible to eliminate the residual potential at the cleaner position as circled in the graph of FIG.
[0106]
Although the graph shows the pre-exposure position as a measurement position for convenience, the image forming apparatus according to the second embodiment has a configuration in which the pre-exposure is omitted because of the apparatus configuration.
[0107]
As described above, in the present embodiment, in the cleaning device having a configuration in which the frequency can be easily controlled, the pre-exposure is eliminated by applying the DC potential corresponding to the remaining potential on the surface of the image carrier, thereby reducing the cost and stabilizing the cost. A cleaning device exhibiting cleaning performance can be provided.
[0108]
【The invention's effect】
As described above, according to the image forming apparatus of the present invention, in the image forming apparatus provided with the cleaning unit that contacts the surface of the rotating image carrier and cleans the residual toner on the surface of the image carrier, The cleaning means at the time of body contact cleaning vibrates, and its frequency f is the image carrier rotation speed P, and the nip width n which is the contact point between the image carrier and the cleaning means is n. Focusing on the amount of movement, design items such as the amount of intrusion between the image carrier and the cleaning device, the set angle, the rebound resilience, etc., so as to satisfy the relationship of f ≧ P / n, thereby obtaining an optimum cleaning ability. It becomes possible.
[0109]
In addition, a stable cleaning device can be provided by selecting a rebound resilience and using a cleaning means in order to obtain a predetermined frequency.
[0110]
Further, in an image forming apparatus provided with a cleaning unit which is in contact with the surface of the rotating image carrier and cleans residual toner on the surface of the image carrier, the cleaning unit at the time of contact cleaning of the image carrier is driven, and its frequency is: f is an image carrier rotation speed: P, and a nip width: n, which is a contact point between the image carrier and the cleaning means, is focused on a moving amount of the image carrier passing through the nip, and f ≧ P / n. As described above, the provision of the control means for controlling the vibration of the cleaning means has resulted in obtaining stable cleaning performance from low-temperature and low-humidity environments to high-temperature and high-humidity environments.
[0111]
Further, by using an applying means for applying an alternating current as a control means for controlling the vibration, it has been possible to provide a stable cleaning device with a configuration in which the frequency can be easily controlled.
[0112]
Furthermore, by providing a DC applying means for applying a DC potential corresponding to the residual potential of the image carrier to the AC current, the cleaning device enables simultaneous cleaning and static elimination, eliminates pre-exposure, reduces costs, and achieves high cleaning performance. Has been provided.
[Brief description of the drawings]
FIG. 1 is a graph showing a temperature characteristic of a rebound resilience of a cleaning blade used in a first embodiment of an image forming apparatus according to the present invention.
FIG. 2 is an enlarged view of a cleaning device used in a second embodiment of the image forming apparatus according to the present invention.
FIG. 3 is a graph of an image carrier surface potential at each process position in a third embodiment of the image forming apparatus according to the present invention.
FIG. 4 is a configuration diagram illustrating a form of an image forming apparatus according to a conventional example.
5 is an enlarged view of the cleaning device 13 shown in FIG.
FIG. 6 is a schematic diagram showing a behavior at a blade nip portion in contact with a photosensitive drum in a conventional image forming apparatus.
FIG. 7 is a graph of an image carrier surface potential at each process position in a conventional image forming apparatus.
[Explanation of symbols]
1 Photosensitive drum
40 toner
41 Cleaning blade
42 Magnetic brush roller
43 blade holder
44 Pressure spring
50 AC applying device

Claims (12)

An image forming apparatus comprising: a cleaning unit that contacts a surface of a rotating image carrier and cleans residual toner on the surface of the image carrier.
The cleaning unit vibrates during the image carrier contact cleaning,
The frequency f of the vibration is represented by a relational expression, where P is the rotation speed of the image carrier, and n is a nip width that is a contact point between the image carrier and the cleaning unit.
f ≧ P / n
An image forming apparatus having a configuration satisfying the following. 2. The image forming apparatus according to claim 1, wherein the relational expression is satisfied by setting the temperature of the cleaning unit such that the cleaning unit has a predetermined rebound resilience. The cleaning means,
The image forming apparatus according to claim 1, wherein the image forming apparatus is an elastic blade. In order to satisfy the above relational expression,
4. The image forming apparatus according to claim 1, further comprising a control unit configured to control a vibration of the cleaning unit during the cleaning of the image carrier. The control means includes:
The image forming apparatus according to claim 4, further comprising an application unit configured to apply an alternating current having a predetermined frequency determined from the relational expression to the cleaning unit. The control means includes:
When controlling the vibration of the cleaning unit at the time of the image carrier contact cleaning,
The image forming apparatus according to claim 4, wherein the cleaning unit includes a DC application unit that applies a DC potential that cancels a residual potential of the image carrier. An image forming method for an image forming apparatus, comprising: a cleaning unit that contacts a surface of a rotating image carrier and cleans residual toner on the surface of the image carrier.
The cleaning unit vibrates during the image carrier contact cleaning,
The frequency f of the vibration is represented by a relational expression, where P is the rotation speed of the image carrier, and n is a nip width that is a contact point between the image carrier and the cleaning unit.
f ≧ P / n
An image forming method characterized by forming an image with a configuration satisfying the following. 8. The image forming method according to claim 7, wherein the relational expression is satisfied by setting the temperature of the cleaning unit such that the cleaning unit has a predetermined rebound resilience. The cleaning means,
The image forming method according to claim 7, wherein the image forming method is an elastic blade. In order to satisfy the above relational expression,
The control means,
The image forming method according to any one of claims 7 to 9, further comprising a step of controlling a vibration of the cleaning unit during the contact cleaning of the image carrier. The application means provided in the control means,
The image forming method according to claim 10, further comprising: applying an alternating current having a predetermined frequency determined from the relational expression to the cleaning unit. DC application means provided in the control means,
When controlling the vibration of the cleaning unit at the time of the image carrier contact cleaning,
The image forming method according to claim 10, further comprising applying a DC potential to the cleaning unit to cancel a residual potential of the image carrier.

Images