JP2015152771A5

JP2015152771A5 -

Info

Publication number: JP2015152771A5
Application number: JP2014026523A
Authority: JP
Filing date: 2014-02-14
Publication date: 2017-03-16
Anticipated expiration: 2034-02-14

Description

一方、上述したトナー付着による被転写部材の汚れは、用紙のサイズより大きなサイズのトナー像が像担持体上に形成され、用紙をはみ出した領域に存在するトナーが転写部材に付着した場合に、転写部材に付着したトナーが更に移動し用紙に付着することで生じる。この汚れは、たとえばいわゆる用紙の裏汚れとして発生する。
用紙のサイズより大きなサイズのトナー像が像担持体上に形成される現象は、例えば、原稿載置台に載せられる原稿が厚い場合に生じる。厚い原稿を用いる場合は、原稿を原稿カバーで押さえても、原稿の側部から走査光が漏れ出し、走査光が原稿カバーで反射されて非画像領域と判断されるべき部分に画像が形成されてしまうことがあるためである。
一方、裏汚れが発生する他の要因として、非画像領域で現像されたドラム状の感光体上の地汚れトナー（弱・逆帯電トナーが主）が転写部材に転移し、転移後、蓄積されたトナーが転写紙に転写することが挙げられる。
以上の事情から、転写部材に付着したトナーが被転写部材に転移することを極力抑制することが望ましい。
このためには、紙間のタイミングにおける、転写部材と像担持体との間の、転写電界と同極性の電界は、大きいほうが良い。これは、転写部材に付着したトナーの多くが逆帯電トナーであるという性質を有するからである。また、非画像領域の転写電流（正極）を上げることで地汚れトナーを跳ね除けることにより、転写部材への汚れを溜めにくくして裏汚れの悪化を防止することも考えられる。 On the other hand, the contamination of the member to be transferred due to the adhesion of the toner described above is caused when a toner image having a size larger than the size of the paper is formed on the image carrier and the toner existing in the region protruding from the paper adheres to the transfer member. This occurs when the toner adhering to the transfer member further moves and adheres to the paper. This stain occurs, for example, as a so-called back stain of the paper.
The phenomenon that a toner image having a size larger than the size of the paper is formed on the image carrier occurs, for example, when a document placed on the document placing table is thick. When a thick original is used, even if the original is held down by the original cover, the scanning light leaks from the side of the original, and the scanning light is reflected by the original cover and an image is formed in a portion that should be determined as a non-image area. This is because there are cases where the
On the other hand, as another cause of back stain, the ground toner (mainly weakly and reversely charged toner) on the drum-shaped photosensitive member developed in the non-image area is transferred to the transfer member and accumulated after the transfer. Transfer of the toner to transfer paper.
From the above circumstances, it is desirable to suppress as much as possible that the toner adhering to the transfer member is transferred to the transfer target member.
For this purpose, the electric field having the same polarity as the transfer electric field between the transfer member and the image carrier at the timing between the sheets is preferably large. This is because most of the toner adhering to the transfer member has a property of being reversely charged toner. In addition, it is conceivable that by increasing the transfer current (positive electrode) in the non-image area, the background toner can be removed to make it difficult to collect dirt on the transfer member, thereby preventing the back dirt from deteriorating.

この目的を達成するため、本発明は、像担持体に対向して配置され、前記像担持体に担持されたトナー像を被転写部材に転写するための転写電界を前記像担持体との間の転写領域に形成する転写部材と、前記転写部材をクリーニングするために前記被転写部材が前記転写領域を非通過のときに前記転写領域に形成されるクリーニング電界を、前記被転写部材の表面平滑度に基づいて制御する電界形成制御部と、を備えた画像形成装置にある。 In order to achieve this object, the present invention provides a transfer electric field between the image carrier and the image carrier that is disposed opposite to the image carrier and transfers a toner image carried on the image carrier to a transfer member. of a transfer member forming the transfer region, the cleaning electric field in which the target transfer member for cleaning the front Symbol transfer member is formed in the transfer region during the non-passage of the transfer area, the surface of the transfer target member in an image forming apparatus having the electric field formation control unit that controls, based on the smoothness, the.

上記平滑度センサＳ１あるいはＳ２は、図５に示すように、転写ローラ１４Ａや帯電ローラなどの帯電部材における転写バイアスや帯電バイアスを制御するための電界形成制御部１００に接続される。
電界形成制御部１００は、画像形成装置１の画像形成シーケンス制御を行う制御部が用いられ、本実施の形態に関係する部材として、入力側に上記平滑度センサＳ１(平滑度センサＳ２は括弧を付して示す)が接続されている。
なお、電界形成制御部１００は、前述したように、画像形成シーケンス制御を実行する制御部であるので、図示しないが、前述した画像形成の際のプロセス条件を決めるための入力部材も接続されている。
電界形成制御部１００の出力側には、本実施の形態に関係する部材として、帯電部材の一つである転写装置１４に用いられる転写ローラ１４Ａへのバイアス駆動回路１０１が接続されている。なお、図示しないが、帯電装置１１の帯電ローラを対象とするバイアス駆動回路も制御手順が異なるものの接続されている。 As shown in FIG. 5, the smoothness sensor S1 or S2 is connected to an electric field formation control unit 100 for controlling a transfer bias and a charging bias in a charging member such as a transfer roller 14A and a charging roller.
As the electric field formation control unit 100, a control unit that performs image formation sequence control of the image forming apparatus 1 is used. As a member related to the present embodiment, the smoothness sensor S1 (smoothness sensor S2 has parentheses on the input side). Are attached ).
As described above, the electric field formation control unit 100 is a control unit that executes image formation sequence control. Therefore, although not shown, an input member for determining the process conditions in the above-described image formation is also connected. Yes.
On the output side of the electric field formation control unit 100, a bias drive circuit 101 to a transfer roller 14A used in the transfer device 14 which is one of charging members is connected as a member related to the present embodiment. Although not shown, a bias driving circuit for the charging roller of the charging device 11 is also connected although the control procedure is different.

一方、上述した転写前、通紙間および転写工程直後での電流印加が行われると、転写工程時に用紙から転写ローラ１４Ａに付着した紙粉が転写バイアス極性により帯電することになる。転写バイアス極性が、感光体１０の帯電極性と逆極性の関係となっている場合、紙粉は転写バイアスによって転写ローラ１４Ａでの極性と同極に帯電していることで転写ローラ１４Ａ側での電流印加によって感光体１０側に転移しやすくなる。
転写ローラ１４Ａ側から感光体１０に向けて転移し、感光体１０に付着した紙粉は、前述したように、トナーのサイズよりも小さい。このため、クリーニング装置１５をすり抜けると、転写ローラ１４Ａと同様に帯電部材である帯電装置１１の帯電ローラに付着しやすくなる。
帯電ローラに紙粉が付着した場合には、前述したように、感光体１０への一様帯電が阻害され、紙粉の付着した位置では帯電が不均一となって黒スジなどの異常画像が発生する。また、前述したように、感光体１０に付着した紙粉が現像装置１３において回収されると現像剤、特にトナーの帯電特性を阻害することになる。 On the other hand, when current application is performed before transfer, between paper passing, and immediately after the transfer process, paper dust attached to the transfer roller 14A from the paper during the transfer process is charged by the transfer bias polarity. When the transfer bias polarity is opposite to the charging polarity of the photoconductor 10, the paper dust is charged to the same polarity as that of the transfer roller 14A by the transfer bias. It becomes easy to transfer to the photoconductor 10 side by applying current.
As described above, the paper dust that has transferred from the transfer roller 14A side toward the photoconductor 10 and adhered to the photoconductor 10 is smaller than the size of the toner. For this reason, when passing through the cleaning device 15, it easily adheres to the charging roller of the charging device 11, which is a charging member, like the transfer roller 14 </ b> A.
When paper dust adheres to the charging roller, as described above, uniform charging to the photoconductor 10 is hindered, and charging becomes uneven at the position where the paper dust adheres, and abnormal images such as black streaks appear. Occur. Further, as described above, when the paper dust attached to the photoconductor 10 is collected by the developing device 13, the charging characteristics of the developer, particularly the toner, are hindered.

感光体１０の非画像部から転写ローラ１４Ａにトナーが付着するのを回避するために、上述した転写ローラ１４Ａ側での電流印加を行う際には、電流値が高い方がトナーの転移を阻止する上で効果的である。しかし、電流値を高くすると紙粉での帯電状態が高まり、感光体１０に向けて反発しやすくなる。このため、感光体１０に紙粉が付着し易くなり、クリーニングをすり抜けた場合の不具合が発生しやすくなる。このように、転写ローラ１４Ａでのトナー付着防止と感光体１０への紙粉付着防止は、トレードオフの関係となる。 In order to avoid the toner from adhering to the transfer roller 14A from the non-image portion of the photoconductor 10, when the current is applied on the transfer roller 14A side described above, the higher current value prevents toner transfer. It is effective in doing. However, when the current value is increased, the charged state with the paper dust increases, and repulsion toward the photoreceptor 10 is likely to occur. For this reason, paper dust is likely to adhere to the photoconductor 10, and problems are likely to occur when cleaning is passed. Thus, the prevention of toner adhesion at the transfer roller 14A and the prevention of paper dust adhesion to the photoreceptor 10 are in a trade-off relationship.

ところで、電界形成制御部１００では、用紙の平滑度に応じたクリーニング電界を形成するためのバイアスの制御に加えて、使用環境条件の変化に基づき上記クリーニング電界形成用のバイアスを更改して決定したうえで制御することも可能である。
紙粉による黒スジ等の異常画像が発生する機会として、低温低湿環境が強まる程、異常画像が発生しやすくなることが発明者の実験によって確認されている。
そこで、電界形成制御部１００の入力側には、図５に示すように、用紙を給送する使用環境条件を検知可能な環境条件検知手段としての温度センサＳ３と、湿度センサＳ４とが接続されている。これらセンサは、図１に示すように、用紙Ｐの温湿度に影響を与えやすい位置である給紙装置４の上方および定着装置７の近傍にそれぞれ配置されている。
電界形成制御部１００は、環境条件検知結果である温度湿度等の環境条件に基づき、前述した用紙の平滑度に応じて決定されたクリーニング電界を形成するためのバイアス制御条件を更改して制御する。この場合に用いられる環境補正係数は、平滑度係数と同様に実験により求めた標準設定値に対する補正値であり、表２に示す条件に基づき選択され、式（２）により環境条件の変化に対応して更改された転写バイアスが求められる。
クリーニング電界形成用バイアス＝標準設定値×平滑度係数×環境補正係数・・・（２） By the way, the electric field formation control unit 100 determines the cleaning electric field forming bias again based on the change of the use environment condition in addition to the control of the bias for forming the cleaning electric field according to the smoothness of the paper. It is also possible to control the above.
As an opportunity to generate an abnormal image such as black streaks due to paper dust, it has been confirmed by experiments of the inventor that an abnormal image is more likely to occur as the low-temperature and low-humidity environment becomes stronger.
Therefore, the input side of the electric field control unit 100, as shown in FIG. 5, a temperature sensor S3 as detectable environmental conditions detection means the operating environment for feeding the paper, is connected to the humidity sensor S4 Tei Ru. These sensors, as shown in FIG. 1, are respectively arranged in the vicinity of the upper and the fixing device 7 of the feeding device 4 is given position easily influence the temperature and humidity of the paper P.
The electric field formation control unit 100 renews and controls the bias control condition for forming the cleaning electric field determined according to the smoothness of the paper based on the environmental condition such as temperature and humidity as the environmental condition detection result. . The environmental correction coefficient used in this case is a correction value for the standard set value obtained by experiment in the same manner as the smoothness coefficient, and is selected based on the conditions shown in Table 2, and responds to changes in the environmental conditions according to Equation (2) Thus, a renewed transfer bias is required.
Cleaning field forming bias = standard setting value × smoothness coefficient × environment correction coefficient (2)

以上、本発明の好ましい実施の形態について説明したが、本発明はかかる特定の実施形態に限定されるものではなく、上述の説明で特に限定していない限り、特許請求の範囲に記載された本発明の趣旨の範囲内において、種々の変形・変更が可能である。
例えば、平滑度センサとして、光学センサの一つである撮像素子を用いたドップラー効果を利用する構成等を適用することもできる。
本発明の実施の形態に記載された効果は、本発明から生じる最も好適な効果を列挙したに過ぎず、本発明による効果は、本発明の実施の形態に記載されたものに限定されるものではない。 As mentioned above, although preferable embodiment of this invention was described, this invention is not limited to this specific embodiment, Unless it is specifically limited by the above-mentioned description, this invention described in the claim is described. Various modifications and changes are possible within the scope of the gist of the invention.
For example , a configuration using a Doppler effect using an imaging element which is one of optical sensors can be applied as the smoothness sensor.
The effects described in the embodiments of the present invention are only the most preferable effects resulting from the present invention, and the effects of the present invention are limited to those described in the embodiments of the present invention. is not.

１画像形成装置
１０感光体（像担持体）
１４Ａ転写ローラ（転写部材）
１００電界形成制御部
Ｐ用紙（被転写部材）
Ｓ１，Ｓ２平滑度センサ（物性検知手段）
Ｓ３温度センサ（環境条件検知手段）
Ｓ４湿度センサ（環境条件検知手段） 1 image forming apparatus 10 photoconductor (image carrier)
14A transfer roller (transfer member)
100 Electric field formation control unit P paper (member to be transferred)
S1, S2 smoothness sensor (physical property detection means)
S3 temperature sensor (environmental condition detection means)
S4 humidity sensor (environmental condition detection means)

Claims

Disposed opposite the image bearing member, a transfer member forming a transfer electric field for transferring the toner image carried on the image carrier to a transfer member in the transfer area between the image bearing member,
The cleaning electric field in which the target transfer member for cleaning the front Symbol transfer member is formed in the transfer area when the non-passing the transfer region, the electric field forming control for controlling on the basis of the surface smoothness of the transfer member an image forming apparatus including a part, a.

The image forming apparatus according to claim 1, wherein the cleaning electric field has the same polarity as the transfer electric field and is smaller in absolute value than the transfer electric field.

The image forming apparatus according to claim 1 , further comprising a smoothness sensor that is provided on a transport path upstream of the transfer region in the transport direction of the transferred member and detects a surface smoothness of the transferred member.

Electric field forming control unit, before Symbol image forming apparatus according to any one of claims 1 to 3, larger in absolute value the cleaning electric field higher surface smoothness of the transfer member.

An environmental condition detection means for detecting an environmental condition of use of the image forming apparatus;
The electric field formation control unit controls the cleaning electric field based on a detection result of a use environment by the environmental condition detection unit as well as a surface smoothness of the transferred member. The image forming apparatus described in 1.

The electric field formation control unit further updates the conditions for forming the cleaning electric field determined based on the surface smoothness of the transferred member based on the detection result of the use environment by the environmental condition detection means. The image forming apparatus according to claim 5, wherein the cleaning electric field is controlled.

The image forming apparatus according to claim 1, wherein the polarity of the cleaning electric field is the same as the polarity of the reversely charged toner attached to the transfer member.

The image carrier is a drum-shaped photoconductor,
The transferred member is paper,
The image forming apparatus according to claim 1, wherein the toner image carried on the photoconductor is directly transferred onto a sheet.