JP3271811B2 - Image forming device - Google Patents
Image forming deviceInfo
- Publication number
- JP3271811B2 JP3271811B2 JP01015993A JP1015993A JP3271811B2 JP 3271811 B2 JP3271811 B2 JP 3271811B2 JP 01015993 A JP01015993 A JP 01015993A JP 1015993 A JP1015993 A JP 1015993A JP 3271811 B2 JP3271811 B2 JP 3271811B2
- Authority
- JP
- Japan
- Prior art keywords
- transfer
- image forming
- belt
- forming apparatus
- contact
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
- 238000011144 upstream manufacturing Methods 0.000 claims description 15
- 108091008695 photoreceptors Proteins 0.000 claims description 14
- 239000010425 asbestos Substances 0.000 claims 1
- 229910052895 riebeckite Inorganic materials 0.000 claims 1
- 238000000926 separation method Methods 0.000 description 14
- 238000005513 bias potential Methods 0.000 description 7
- 230000006866 deterioration Effects 0.000 description 6
- 238000010586 diagram Methods 0.000 description 5
- 230000007613 environmental effect Effects 0.000 description 4
- 210000000078 claw Anatomy 0.000 description 2
- 238000009826 distribution Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000002474 experimental method Methods 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- CBENFWSGALASAD-UHFFFAOYSA-N Ozone Chemical compound [O-][O+]=O CBENFWSGALASAD-UHFFFAOYSA-N 0.000 description 1
- 238000004140 cleaning Methods 0.000 description 1
- 230000002950 deficient Effects 0.000 description 1
- 239000003989 dielectric material Substances 0.000 description 1
- 230000005684 electric field Effects 0.000 description 1
- 238000002347 injection Methods 0.000 description 1
- 239000007924 injection Substances 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 230000008719 thickening Effects 0.000 description 1
- 230000037303 wrinkles Effects 0.000 description 1
Classifications
-
- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
- G03G15/00—Apparatus for electrographic processes using a charge pattern
- G03G15/65—Apparatus which relate to the handling of copy material
- G03G15/6532—Removing a copy sheet form a xerographic drum, band or plate
- G03G15/6535—Removing a copy sheet form a xerographic drum, band or plate using electrostatic means, e.g. a separating corona
-
- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
- G03G15/00—Apparatus for electrographic processes using a charge pattern
- G03G15/14—Apparatus for electrographic processes using a charge pattern for transferring a pattern to a second base
- G03G15/16—Apparatus for electrographic processes using a charge pattern for transferring a pattern to a second base of a toner pattern, e.g. a powder pattern, e.g. magnetic transfer
-
- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
- G03G15/00—Apparatus for electrographic processes using a charge pattern
- G03G15/14—Apparatus for electrographic processes using a charge pattern for transferring a pattern to a second base
- G03G15/16—Apparatus for electrographic processes using a charge pattern for transferring a pattern to a second base of a toner pattern, e.g. a powder pattern, e.g. magnetic transfer
- G03G15/1605—Apparatus for electrographic processes using a charge pattern for transferring a pattern to a second base of a toner pattern, e.g. a powder pattern, e.g. magnetic transfer using at least one intermediate support
-
- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
- G03G15/00—Apparatus for electrographic processes using a charge pattern
- G03G15/14—Apparatus for electrographic processes using a charge pattern for transferring a pattern to a second base
- G03G15/16—Apparatus for electrographic processes using a charge pattern for transferring a pattern to a second base of a toner pattern, e.g. a powder pattern, e.g. magnetic transfer
- G03G15/1665—Apparatus for electrographic processes using a charge pattern for transferring a pattern to a second base of a toner pattern, e.g. a powder pattern, e.g. magnetic transfer by introducing the second base in the nip formed by the recording member and at least one transfer member, e.g. in combination with bias or heat
- G03G15/167—Apparatus for electrographic processes using a charge pattern for transferring a pattern to a second base of a toner pattern, e.g. a powder pattern, e.g. magnetic transfer by introducing the second base in the nip formed by the recording member and at least one transfer member, e.g. in combination with bias or heat at least one of the recording member or the transfer member being rotatable during the transfer
- G03G15/1675—Apparatus for electrographic processes using a charge pattern for transferring a pattern to a second base of a toner pattern, e.g. a powder pattern, e.g. magnetic transfer by introducing the second base in the nip formed by the recording member and at least one transfer member, e.g. in combination with bias or heat at least one of the recording member or the transfer member being rotatable during the transfer with means for controlling the bias applied in the transfer nip
-
- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
- G03G2215/00—Apparatus for electrophotographic processes
- G03G2215/16—Transferring device, details
- G03G2215/1604—Main transfer electrode
- G03G2215/1623—Transfer belt
-
- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
- G03G2215/00—Apparatus for electrophotographic processes
- G03G2215/16—Transferring device, details
- G03G2215/1647—Cleaning of transfer member
- G03G2215/1661—Cleaning of transfer member of transfer belt
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Electrostatic Charge, Transfer And Separation In Electrography (AREA)
- Control Or Security For Electrophotography (AREA)
- Color Electrophotography (AREA)
- Fax Reproducing Arrangements (AREA)
- Decoration By Transfer Pictures (AREA)
- Combination Of More Than One Step In Electrophotography (AREA)
Description
【０００１】[0001]
【産業上の利用分野】本発明は、感光体上に形成された
トナー像が被転写体に転写される複写機，プリンタ，フ
ァクシミリ等の画像形成装置に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as a copying machine, a printer, a facsimile, etc., in which a toner image formed on a photoreceptor is transferred to a transfer target.
【０００２】[0002]
【従来の技術】複写機等の画像形成装置において、感光
体上のトナー像を転写紙等に転写してこの転写紙等を感
光体から分離する転写分離装置としては、一般に、転写
用コロナ放電器により転写紙等の裏面側にコロナ放電を
行って感光体上のトナー像を転写紙等の表面側に転写さ
せ、分離用コロナ放電器により転写紙等の裏面側にコロ
ナ放電を行うことにより転写紙等を感光体から分離して
搬送装置により搬送するコロナ転写分離方式が使用され
ている。2. Description of the Related Art In an image forming apparatus such as a copying machine, a transfer separation device for transferring a toner image on a photoreceptor onto transfer paper or the like and separating the transfer paper or the like from the photoreceptor is generally a transfer corona discharger. By performing corona discharge on the back side of the transfer paper with an electric device to transfer the toner image on the photoreceptor to the front side of the transfer paper, etc., and performing corona discharge on the back side of the transfer paper etc. with the corona discharger for separation A corona transfer separation system in which transfer paper or the like is separated from a photoconductor and transferred by a transfer device is used.
【０００３】また、転写ベルトを回動させながらこの転
写ベルトに電源からバイアス電位を印加して感光体上の
トナー像を転写ベルト上の転写紙等に転写し、転写ベル
トで転写紙等を静電的に吸着して感光体から分離し搬送
する接触型転写分離方式が提案されている。この接触型
転写分離方式において、転写ベルトの代りに転写ローラ
を用いたものもあり、この接触型転写分離方式は特開平
２−１２３３８５号公報，特開平２−１２３３８６号公
報，特開平２−２８７３８０号公報，特開平２−２８７
３８１号公報，特開平３−６８９７６号公報などにより
知られている。Further, while rotating the transfer belt, a bias potential is applied from a power supply to the transfer belt to transfer the toner image on the photoreceptor to a transfer paper or the like on the transfer belt, and the transfer paper or the like is statically moved by the transfer belt. There has been proposed a contact-type transfer / separation system in which the toner is electrically attracted, separated from the photoreceptor, and transported. In this contact transfer separation method, a transfer roller is used in place of the transfer belt. This contact transfer separation method is disclosed in JP-A-2-123385, JP-A-2-123386, and JP-A-2-287380. No., JP-A-2-287
381 and JP-A-3-68976.
【０００４】また、複写機等の電子写真方式の画像形成
装置には、転写領域でトナー像が転写され、このトナー
像を担持して回転により搬送する担持体を有するものが
ある。この画像形成装置では、感光体上にトナー像を形
成し、このトナー像を第１の転写領域でベルトに転写す
る。そして、ベルト上のトナー像をベルトの回転により
第２の転写領域まで搬送して転写紙へ転写する。ここ
に、ベルトには第１の転写領域の上流側で転写電位を印
加し、この転写電位によりトナー像を感光体からベルト
に転写させている。Some electrophotographic image forming apparatuses such as copiers have a carrier on which a toner image is transferred in a transfer area and which carries the toner image by rotation. In this image forming apparatus, a toner image is formed on a photoconductor, and the toner image is transferred to a belt in a first transfer area. Then, the toner image on the belt is conveyed to the second transfer area by the rotation of the belt and is transferred to a transfer sheet. Here, a transfer potential is applied to the belt on the upstream side of the first transfer area, and the toner image is transferred from the photoconductor to the belt by the transfer potential.
【０００５】[0005]
【発明が解決しようとする課題】上記接触型転写分離方
式は上記コロナ転写分離方式に比べてオゾンの発生が少
なくなり、電源の電圧が少なくてすむ等のメリットがあ
る。しかしながら、転写ベルトを用いる場合には、転写
ベルトの抵抗値ムラ、環境変動、転写紙等の種類、トナ
ー像の面積等によって電源の転写ベルトに対する適正な
印加バイアス電位が変化し、良好なトナー像転写を行え
なくなってしまう。その理由は、転写ベルトにおける電
源のバイアス電位印加による電荷量が転写ベルトの製造
時の抵抗値ムラ、環境変化による抵抗値の変化、転写紙
等の材質の違いおよび厚みの違いなどによって良好なト
ナー像転写に必要な値より変化してしまうためである。
すなわち、転写ベルトにおける電源の印加バイアス電位
による電荷量が良好なトナー像転写に必要な値である場
合には図６に示すように感光体３７と転写ベルトとが当
接するニップ部の転写領域より上流側のプレ転写領域で
放電が発生せず、感光体３７上の例えば正極性に帯電し
たトナー３９が転写領域で転写ベルト上の転写紙３８に
転移される。この場合、転写ベルトには電源によりバイ
アス電位が印加されている。また、転写ベルトにおける
電源の印加バイアス電位による電荷量が転写ベルトの製
造時の抵抗値ムラ、環境変化による抵抗値の変化、転写
紙等の材質の違いおよび厚みの違いなどによって良好な
トナー像転写に必要な値より変化した場合には図７に示
すようにプレ転写領域で強電界がかかって放電が発生す
る。その結果、トナーに負の電荷が付いて転写ベルト上
の転写紙３８の表裏に正，負の電荷が生じ、転写ベルト
に電源から適正なバイアス電位が印加されていても感光
体３７上のトナー３９が転写ベルト上の転写紙３８に転
移せずに転写紙上の転写画像の白抜けが発生してしま
う。The contact-type transfer separation method has the advantage that the generation of ozone is smaller than that of the corona transfer separation method, and the voltage of the power supply can be reduced. However, when a transfer belt is used, an appropriate bias potential of the power supply to the transfer belt changes depending on unevenness in the resistance value of the transfer belt, environmental fluctuations, the type of transfer paper, the area of the toner image, and the like. Transfer cannot be performed. The reason for this is that the amount of charge caused by the application of the bias potential of the power supply on the transfer belt is a good toner due to uneven resistance values during the manufacture of the transfer belt, changes in resistance values due to environmental changes, differences in the material and thickness of the transfer paper, etc. This is because the value is changed from a value necessary for image transfer.
That is, when the amount of charge due to the applied bias potential of the power supply on the transfer belt is a value necessary for good toner image transfer, as shown in FIG. 6 , the transfer area of the nip portion where the photosensitive member 37 and the transfer belt come into contact with each other is reduced . No discharge occurs in the pre-transfer area on the upstream side, and for example, the positively charged toner 39 on the photoconductor 37 is transferred to the transfer paper 38 on the transfer belt in the transfer area. In this case, a bias potential is applied to the transfer belt by a power supply. In addition, the amount of electric charge due to the bias potential of the power supply applied to the transfer belt is excellent in transfer of the toner image due to unevenness in resistance value during manufacture of the transfer belt, change in resistance value due to environmental change, difference in material and thickness of transfer paper and the like. In the case where the value is changed from the required value, a strong electric field is applied in the pre-transfer area as shown in FIG . As a result, positive and negative charges are generated on the front and back of the transfer paper 38 on the transfer belt due to the negative charge of the toner, and even if an appropriate bias potential is applied to the transfer belt from the power supply, the toner on the photoreceptor 37 is not charged. 39 does not transfer to the transfer paper 38 on the transfer belt, and a white spot occurs on the transfer image on the transfer paper.
【０００６】また、転写ベルトは感光体上のトナー像を
転写ベルト上の転写紙等に転写するだけでなく、転写ベ
ルトで転写紙等を静電的に吸着して感光体から分離する
が、転写紙等の分離性は環境条件によって変化する。特
に、高温高湿の条件下で転写紙等の含水分が多くなる
と、転写ベルトに転写紙等が吸着されなくなり、転写紙
等が感光体の方に吸着されてしまって感光体から分離で
きなくなってしまう。そこで、分離爪により転写紙等を
感光体から分離しようとすれば、転写紙等に分離爪によ
る跡や皺などができてしまい、画像品質が落ちてしま
う。The transfer belt not only transfers the toner image on the photoreceptor to a transfer paper or the like on the transfer belt, but also separates the transfer paper or the like from the photoreceptor by electrostatically attracting the transfer paper or the like with the transfer belt. The separability of transfer paper and the like changes depending on environmental conditions. In particular, when the moisture content of the transfer paper or the like increases under the condition of high temperature and high humidity, the transfer paper or the like is not adsorbed to the transfer belt, and the transfer paper or the like is adsorbed toward the photoconductor and cannot be separated from the photoconductor. Would. Therefore, if the transfer paper or the like is to be separated from the photoconductor by the separation claw, marks or wrinkles are formed on the transfer paper or the like by the separation claw, and the image quality is degraded.
【０００７】上記電子写真方式の画像形成装置では、ベ
ルトには第１の転写領域の上流側で転写電位をベルトに
印加してこの転写電位によりトナー像を感光体からベル
トに転写させるので、トナーが第１の転写領域の上流側
でベルトに飛翔する現象が生じ、ラインの太りや文字等
のニジミ，シャープ性の劣化といわれる画像劣化が発生
する。本発明は、上記欠点を改善し、良好な転写を行う
ことができて画像劣化を防止でき且つどのような環境下
でも被転写体の分離性が良い画像形成装置を提供するこ
とを目的とする。In the above electrophotographic image forming apparatus, a transfer potential is applied to the belt on the upstream side of the first transfer area, and the toner image is transferred from the photosensitive member to the belt by the transfer potential. Is caused to fly on the belt on the upstream side of the first transfer area, and image deterioration called thickening of lines, blurring of characters and the like, and deterioration of sharpness occurs. SUMMARY OF THE INVENTION An object of the present invention is to provide an image forming apparatus which can improve the above-mentioned drawbacks, can perform good transfer, can prevent image deterioration, and has good separability of an object under any environment. .
【０００８】[0008]
【課題を解決するための手段】上記目的を達成するた
め、請求項１記載の発明は、トナー像が形成される感光
体と、この感光体に対して所定のニップ幅をもって当接
して移動し、前記感光体上に形成されたトナー像が転写
される被転写体と、この被転写体に所定の転写バイアス
を印加する転写バイアス印加手段と、前記感光体に対し
て転写領域より上流側であって、前記感光体と前記被転
写体との接触開始点までの領域で、前記被転写体に対
し、前記トナー像の前記感光体から前記被転写体への転
移量が増大するごとく前記転写バイアスに電位勾配を持
たせる電位勾配生成手段とを備え、電位勾配生成手段は
定電圧素子を介して接地されている画像形成装置であっ
て、前記転写バイアス印加手段は前記ニップ部に対して
前記被転写体の移動方向下流側で、前記被転写体と接触
する電極であり、前記電位勾配生成手段は前記ニップ部
に対して前記被転写体の移動方向上流側で、前記被転写
体と接触する電極であるものである。In order to achieve the above object, according to the first aspect of the present invention, a photosensitive member on which a toner image is formed contacts a photosensitive member with a predetermined nip width. A transfer member to which the toner image formed on the photosensitive member is transferred, transfer bias applying means for applying a predetermined transfer bias to the transfer member, and a transfer bias upstream of a transfer area with respect to the photosensitive member. And transferring the toner image to the transfer object in an area up to a contact start point between the photoconductor and the transfer object so that a transfer amount of the toner image from the photoconductor to the transfer object increases. A potential gradient generating means for providing a bias with a potential gradient, wherein the potential gradient generating means is an image forming apparatus which is grounded via a constant voltage element.
And the transfer bias applying means is provided with respect to the nip portion.
Contacting the transfer object on the downstream side in the moving direction of the transfer object
The potential gradient generating means is provided in the nip portion.
Relative to the transfer object on the upstream side in the moving direction of the transfer object.
It is an electrode that comes into contact with the body .
【０００９】請求項２記載の発明は、請求項１記載の画
像形成装置において、前記被転写体は、前記感光体に対
して所定のニップ幅をもって当接する転写ベルトに担持
され搬送される転写紙であるものである。[0009] The invention according to claim 2 is an image according to claim 1.
In the image forming apparatus, the object to be transferred is opposed to the photoconductor.
On the transfer belt that comes in contact with the specified nip width
The transfer paper is transferred and conveyed .
【００１０】[0010]
【００１１】[0011]
【作用】請求項１記載の発明では、被転写体は感光体に
対して所定のニップ幅をもって当接して移動し、感光体
上に形成されたトナー像が転写される。被転写体は転写
バイアス印加手段により所定の転写バイアスが印加さ
れ、電位勾配生成手段は感光体に対して転写領域より上
流側であって、感光体と被転写体との接触開始点までの
領域で、被転写体に対し、トナー像の感光体から被転写
体への転移量が増大するごとく転写バイアスに電位勾配
を持たせる。したがって、良好な転写を行うことができ
て画像劣化を防止でき、且つ、被転写体の分離性が良
い。また、電位勾配生成手段が定電圧素子を介して接地
されている。さらに、電極からなる転写バイアス印加手
段は前記ニップ部に対して被転写体の移動方向下流側
で、被転写体と接触し、電極からなる電位勾配生成手段
はニップ部に対して被転写体の移動方向上流側で、被転
写体と接触する。請求項２記載の発明では、請求項１記
載の画像形成装置において、転写ベルトが感光体に対し
て所定のニップ幅をもって当接し、転写紙を担持して搬
送する。 According to the first aspect of the present invention, the transfer object contacts the photosensitive member with a predetermined nip width and moves, and the toner image formed on the photosensitive member is transferred. A predetermined transfer bias is applied to the transfer object by a transfer bias application unit, and the potential gradient generation unit is located on the upstream side of the transfer region with respect to the photoconductor and extends to a contact start point between the photoconductor and the transfer object. Then, the transfer bias is given a potential gradient to the transfer object as the transfer amount of the toner image from the photoconductor to the transfer object increases. Therefore, good transfer can be performed, image deterioration can be prevented, and the transfer object can be easily separated. Further, the potential gradient generating means is grounded via a constant voltage element. Further, the transfer bias applying means composed of an electrode is in contact with the object to be transferred on the downstream side in the movement direction of the object to be transferred with respect to the nip portion, and the potential gradient generating means made of the electrode is configured to apply the potential gradient to the nip portion with respect to the object to be transferred. It comes into contact with the transfer object on the upstream side in the moving direction. In the second aspect of the present invention, claim 1 Symbol
In the image forming apparatus described above, the transfer belt is
Contact with a predetermined nip width to carry the transfer paper and transport it.
Send.
【００１２】[0012]
【実施例】図２は本発明の実施例の前提となる画像形成
装置の一部を示す。この画像形成装置は電子写真方式の
複写機からなる画像形成装置である。感光体ドラムから
なる像担持体１は図示しないが、駆動機構により回転駆
動されて帯電器により均一に帯電された後に書き込み装
置により画像情報が書き込まれて静電潜像が形成され、
この静電潜像が現像器により現像されてトナー像とな
る。また、転写紙からなる記録媒体が給紙装置からレジ
ストローラ２まで給紙されて待機し、レジストローラ２
が感光体ドラム１上のトナー像とのタイミングをとって
転写紙を少なくとも表側が誘電体からなる転写ベルト３
へ送出する。FIG. 2 is a diagram showing an image forming operation according to an embodiment of the present invention.
2 shows a part of the device . This image forming apparatus is an image forming apparatus including an electrophotographic copying machine. Although not shown, the image carrier 1 composed of a photosensitive drum is rotated by a driving mechanism and uniformly charged by a charger, and then image information is written by a writing device to form an electrostatic latent image.
This electrostatic latent image is developed by a developing device to become a toner image. Further, a recording medium composed of transfer paper is fed from the paper feeding device to the registration roller 2 and stands by.
A transfer belt 3 made of a dielectric material at least on the front side of the transfer paper at a timing with the toner image on the photosensitive drum 1
Send to
【００１３】転写ベルト３は駆動ローラ４や他の従動ロ
ーラ５〜７に張架され、ローラ６，７は接地されてい
る。ローラ５は電極を構成する転写バイアスローラであ
り、ローラ４は電気的に浮いた状態に構成されている。
転写紙の先端が感光体ドラム１と転写ベルト３とが当接
する部分の近傍まで来ると同時に、ソレノイド９がオン
して押し上げレバー１０を駆動して押し上げレバー１０
が転写ベルト３およびローラ４〜７を含むベルト装置の
片側を押し上げることにより転写ベルト３が感光体ドラ
ム１に当接する。The transfer belt 3 is stretched around a driving roller 4 and other driven rollers 5 to 7, and the rollers 6, 7 are grounded. The roller 5 is a transfer bias roller constituting an electrode, and the roller 4 is configured to be electrically floating.
At the same time that the leading end of the transfer paper comes close to the portion where the photosensitive drum 1 and the transfer belt 3 come into contact with each other, the solenoid 9 is turned on and the push-up lever 10 is driven to drive the push-up lever 10.
Pushes up one side of the belt device including the transfer belt 3 and the rollers 4 to 7 so that the transfer belt 3 comes into contact with the photosensitive drum 1.
【００１４】駆動ローラ４はモータにより駆動されて回
転し、転写ベルト３が駆動ローラ４により回転駆動され
る。転写ベルト３は感光体ドラム１との当接部分より上
流側で駆動ローラ４と接触し、感光体ドラム１との当接
部分より下流側で転写バイアスローラ５と接触して感光
体ドラム１と所定のニップ幅で当接する。転写ベルト３
が感光体ドラム１に当接すると、図１および図５に示す
ように転写バイアスローラ５に電源８から感光体ドラム
１上のトナーの帯電極性と逆極性の所定バイアス電圧が
印加されて電荷が付与される。転写ベルト３は体積固有
抵抗が中抵抗（１０６〜１０１２Ωｃｍ）であるものが
用いられ、転写バイアスローラ５からのバイアス電圧印
加でローラ６，７側へ電流が流れて電圧が降下して行
く。The drive roller 4 is rotated by being driven by a motor, and the transfer belt 3 is driven to rotate by the drive roller 4. The transfer belt 3 comes into contact with the drive roller 4 on the upstream side of the contact portion with the photosensitive drum 1, and comes into contact with the transfer bias roller 5 on the downstream side of the contact portion with the photosensitive drum 1 to contact the photosensitive drum 1. Contact at a predetermined nip width. Transfer belt 3
1 comes into contact with the photosensitive drum 1, as shown in FIGS. 1 and 5 , a predetermined bias voltage having a polarity opposite to the polarity of the toner charged on the photosensitive drum 1 is applied to the transfer bias roller 5 from the power supply 8 as shown in FIGS. Granted. The transfer belt 3 has a medium volume resistivity of medium resistance (10 6 to 10 12 Ωcm). When a bias voltage is applied from the transfer bias roller 5, a current flows to the rollers 6 and 7 and the voltage drops. go.
【００１５】転写紙は転写ベルト３と感光体ドラム１と
の間を通過する際に転写ベルト３に電源８から感光体ド
ラム１上のトナーの帯電極性と逆極性の所定バイアス電
圧が印加されていることにより感光体ドラム１上のトナ
ー像が転写される。そして、転写紙は電源８から転写ベ
ルト３に付与されている電荷により分極し、この転写紙
の分極電荷と転写ベルト３の真電荷とにより静電気力が
発生してこの静電気力により転写紙が転写ベルト３に吸
着されて転写ベルト３の回動に伴って搬送される。When the transfer paper passes between the transfer belt 3 and the photosensitive drum 1, a predetermined bias voltage having a polarity opposite to the charging polarity of the toner on the photosensitive drum 1 is applied to the transfer belt 3 from a power supply 8. As a result, the toner image on the photosensitive drum 1 is transferred. Then, the transfer paper is polarized by the electric charge applied to the transfer belt 3 from the power supply 8, and an electrostatic force is generated by the polarized charge of the transfer paper and the true charge of the transfer belt 3, and the transfer paper is transferred by the electrostatic force. The transfer belt 3 is attracted to the belt 3 and is conveyed as the transfer belt 3 rotates.
【００１６】転写紙は転写ベルト３による搬送中に中抵
抗の転写ベルト３およびローラ６，７を通してアースへ
電荷が逃がされて帯電量が緩和される。この転写紙の帯
電量が緩和されるスピードは転写紙の持つ抵抗値Ｒと静
電容量Ｃによって大きく左右され、τ＝Ｒ・Ｃなる時定
数で表される。そして、転写紙は転写ベルト３により搬
送されて定着部へ送られるが、定着部の入口付近では帯
電量が緩和されて転写ベルト３との間の静電気力が弱ま
り、小径の接地されているローラ７と転写紙の腰による
曲率分離により転写ベルト３から分離されて定着部でト
ナー像が定着される。この場合、ローラ７の径はφ１４
〜φ１６が適当である。While the transfer paper is being conveyed by the transfer belt 3, charges are released to the ground through the transfer belt 3 and the rollers 6 and 7, which have a medium resistance, so that the charge amount is reduced. The speed at which the amount of charge on the transfer paper is reduced is greatly affected by the resistance value R and the capacitance C of the transfer paper, and is represented by a time constant of τ = RC. Then, the transfer paper is conveyed by the transfer belt 3 and sent to the fixing unit. The amount of charge is reduced near the entrance of the fixing unit, the electrostatic force between the transfer belt 3 and the transfer paper is reduced, and a small-diameter grounded roller is used. The toner image is fixed at the fixing unit by being separated from the transfer belt 3 by the curvature separation of the transfer paper 7 and the waist of the transfer paper. In this case, the diameter of the roller 7 is φ14
~ Φ16 is appropriate.
【００１７】また、転写紙の跡端が感光体ドラム１と転
写ベルト３とのニップ部から抜けると同時にソレノイド
９がオフして押し上げレバー１０の駆動が解除されるこ
とにより転写ベルト３およびローラ４〜７を含むベルト
装置の片側が元の位置に復帰して転写ベルト３が感光体
ドラム１より離れる。これはトナー像の転写を行わない
時に転写ベルト３と感光体ドラム１との接触摩擦による
感光体ドラム１の劣化を防止するために行っている。ま
た、回動中の転写ベルト３の上には感光体ドラム１から
転写紙へ転写されずに飛散したトナーが直接に転写ベル
ト３に付着して残留トナーとなるが、この残留トナーは
接地されているローラ６，７により帯電量が緩和されて
クリーニングブレード１１により掻き落とされて回収ボ
トル１２へ回収される。At the same time as the trailing edge of the transfer paper comes out of the nip portion between the photosensitive drum 1 and the transfer belt 3, the solenoid 9 is turned off and the drive of the push-up lever 10 is released, so that the transfer belt 3 and the roller 4 are released. 7 return to the original position, and the transfer belt 3 is separated from the photosensitive drum 1. This is performed in order to prevent deterioration of the photosensitive drum 1 due to contact friction between the transfer belt 3 and the photosensitive drum 1 when the transfer of the toner image is not performed. Further, the toner scattered without being transferred from the photosensitive drum 1 to the transfer paper directly adheres to the transfer belt 3 and becomes residual toner on the rotating transfer belt 3, but this residual toner is grounded. The amount of charge is reduced by the rollers 6 and 7, scraped off by the cleaning blade 11, and collected by the collection bottle 12.
【００１８】この画像形成装置では、転写ベルト３に電
荷を付与するローラは転写バイアスローラ５のみであ
り、転写バイアスローラ５だけでなく駆動ローラ４にも
電源からバイアス電圧を印加した場合には転写ベルト３
の電位分布が図８に示すようにローラ４，５間において
感光体ドラム１と転写ベルト３とが接触する部分Ｔの間
で直線的に変化する電位勾配が生ずる。実験によれば、
高温高湿の環境下で転写紙の含水分が多くなって８％〜
１１％になると、転写紙が転写ベルト３に静電的に吸着
されなくなる。しかし、この画像形成装置では図５に示
すように転写バイアスローラ５のみにバイアス電圧を印
加した場合には図３に示すように転写紙の感光体ドラム
１に対する分離不良が起きなくなる。これは転写ベルト
３に対して感光体ドラム１より上流側で接触する駆動ロ
ーラ４により電荷を付与した場合には転写紙の含水分量
が多くなることで転写紙の先端部に電荷が入り込んで転
写紙が転写ベルト３に静電的に吸着されなくなるからで
あると考えられる。この画像形成装置のように転写ベル
ト３に駆動ローラ４で電荷を付与しなければ転写紙の搬
送中に電荷が転写紙の先端部に入り込まなくなるので、
転写紙と転写ベルト３との間に反発力が発生しなくて転
写紙の感光体ドラム１に対する分離不良が起きなくな
る。In this image forming apparatus , only the transfer bias roller 5 applies a charge to the transfer belt 3. When a bias voltage is applied from a power source to not only the transfer bias roller 5 but also the drive roller 4, transfer is performed. Belt 3
As shown in FIG. 8 , the potential distribution between the rollers 4 and 5
A linearly varying potential gradient is generated between a portion T where the photosensitive drum 1 and the transfer belt 3 are in contact. According to experiments,
8% ~
At 11%, the transfer paper is not electrostatically attracted to the transfer belt 3. However, in this image forming apparatus , when a bias voltage is applied only to the transfer bias roller 5 as shown in FIG. 5 , poor separation of transfer paper from the photosensitive drum 1 does not occur as shown in FIG. This is because when the electric charge is applied to the transfer belt 3 by the drive roller 4 which is in contact with the photosensitive drum 1 on the upstream side, the moisture content of the transfer paper increases, so that the electric charge enters the leading end of the transfer paper and the transfer is performed. It is considered that the paper is not electrostatically attracted to the transfer belt 3. If no charge is applied to the transfer belt 3 by the drive roller 4 as in this image forming apparatus , the charge does not enter the leading end of the transfer paper during the transfer of the transfer paper.
No repulsive force is generated between the transfer paper and the transfer belt 3, so that the transfer paper is not separated from the photosensitive drum 1 in a defective manner.
【００１９】図４は本発明の一実施例の一部を示す。こ
の実施例は、上記図２に示す画像形成装置において、駆
動ローラ４が電極を構成する転写バイアスローラを兼ね
てこれをバリスタやツェナーダイオードなどの定電圧素
子１３を介して接地するようにしたものである。転写バ
イアスローラ４に印加するバイアス電圧の設定値は特に
規定はないが、下流側の転写バイアスローラ５の印加バ
イアス電圧に近い方が望ましい。FIG. 4 shows a part of an embodiment of the present invention. This embodiment is different from the image forming apparatus shown in FIG. 2 in that the drive roller 4 also serves as a transfer bias roller constituting an electrode and is grounded via a constant voltage element 13 such as a varistor or a Zener diode. It is. The set value of the bias voltage applied to the transfer bias roller 4 is not particularly limited, but is preferably closer to the applied bias voltage of the transfer bias roller 5 on the downstream side.
【００２０】この実施例では、下流側の転写バイアスロ
ーラ５に電源８からバイアス電圧が印加されていて下流
側の転写バイアスローラ５と上流側の転写バイアスロー
ラ４とがほぼ同電位になるので、感光体ドラム１と転写
ベルト３とが当接する転写部の電位が安定して維持され
て転写ベルト３の抵抗値変動やその他の変動によらずに
良好なトナー像転写が行われる。また、高湿時の転写紙
への電荷注入が少なくなり、高湿時における転写紙の感
光体ドラム１に対する分離も良好になる。特に、図２に
示す画像形成装置に比べて、より安定したトナー像の転
写が可能であり、下流側の転写バイアスローラ５に電源
８から印加するバイアス電圧が小さくて良いという特有
の効果を持つ。 In this embodiment , a bias voltage is applied to the transfer bias roller 5 on the downstream side from the power supply 8, and the transfer bias roller 5 on the downstream side and the transfer bias roller 4 on the upstream side have substantially the same potential. The potential of the transfer portion where the photoconductor drum 1 and the transfer belt 3 are in contact with each other is stably maintained, so that a good toner image transfer can be performed irrespective of the fluctuation of the resistance value of the transfer belt 3 and other fluctuations. In addition, the charge injection into the transfer paper at high humidity is reduced, and the separation of the transfer paper from the photosensitive drum 1 at high humidity is also improved. In particular, FIG.
Compared with the image forming apparatus shown in the drawing, it is possible to transfer a toner image more stably, and it has a unique effect that a bias voltage applied from the power supply 8 to the transfer bias roller 5 on the downstream side can be small .
【００２１】[0021]
【発明の効果】以上のように請求項１、２記載の発明に
よれば、トナー像が形成される感光体と、この感光体に
対して所定のニップ幅をもって当接して移動し、前記感
光体上に形成されたトナー像が転写される被転写体と、
この被転写体に所定の転写バイアスを印加する転写バイ
アス印加手段と、前記感光体に対して転写領域より上流
側であって、前記感光体と前記被転写体との接触開始点
までの領域で、前記被転写体に対し、前記トナー像の前
記感光体から前記被転写体への転移量が増大するごとく
前記転写バイアスに電位勾配を持たせる電位勾配生成手
段とを備え、電位勾配生成手段は定電圧素子を介して接
地されている画像形成装置であって、前記転写バイアス
印加手段は前記ニップ部に対して前記被転写体の移動方
向下流側で、前記被転写体と接触する電極であり、前記
電位勾配生成手段は前記ニップ部に対して前記被転写体
の移動方向上流側で、前記被転写体と接触する電極であ
るので、良好な転写を行うことができて画像劣化を防止
でき、且つ、被転写体の分離性が良くなる。しかも、よ
り安定したトナー像の転写が可能であり、転写バイアス
印加手段により被転写体に印加するバイアス電圧が小さ
くて良いという特有の効果を持つ。As described above, according to the first and second aspects of the present invention, the photosensitive member on which a toner image is formed contacts the photosensitive member with a predetermined nip width, and moves. An object to which a toner image formed on the body is transferred,
A transfer bias applying unit for applying a predetermined transfer bias to the transfer target body, and an area upstream of the transfer area with respect to the photosensitive body and in a region up to a contact start point between the photosensitive body and the transfer body. A potential gradient generating means for causing the transfer bias to have a potential gradient as the transfer amount of the toner image from the photoreceptor to the transfer target increases with respect to the transfer object; An image forming apparatus grounded via a constant voltage element , wherein the transfer bias is
The application means is a method for moving the transfer object with respect to the nip portion.
An electrode that is in contact with the object to be transferred on the downstream side,
The potential gradient generating means is configured to move the transfer object with respect to the nip portion.
On the upstream side in the moving direction of the
Since that, to be able to perform a good transfer can prevent image deterioration, and, better separation of the transfer member. In addition, it is possible to transfer a toner image more stably, and there is a unique effect that a bias voltage applied to a transfer target body by a transfer bias applying unit may be small.
【図１】本発明の実施例の前提となる画像形成装置の一
部を示す正面図である。FIG. 1 is a front view showing a part of an image forming apparatus which is a premise of an embodiment of the present invention.
【図２】同画像形成装置を示す断面図である。FIG. 2 is a sectional view showing the image forming apparatus .
【図３】実験の結果を示す図である。FIG. 3 is a diagram showing the results of an experiment.
【図４】本発明の一実施例の一部を示す正面図である。FIG. 4 is a front view showing a part of one embodiment of the present invention.
【図５】上記図２に示す画像形成装置のタイミングチャ
ートである。FIG. 5 is a timing chart of the image forming apparatus shown in FIG. 2 ;
【図６】従来の画像形成装置を説明するための概略図で
ある。FIG. 6 is a schematic diagram for explaining a conventional image forming apparatus.
【図７】従来の画像形成装置を説明するための概略図で
ある。FIG. 7 is a schematic diagram for explaining a conventional image forming apparatus.
【図８】上記図２に示す画像形成装置等の転写ベルトの
電位分布を示す特性図である。FIG. 8 is a characteristic diagram showing a potential distribution of a transfer belt of the image forming apparatus shown in FIG.
１ 感光体 ３ 転写ベルト ４，５ ローラ ８ 電源 Reference Signs List 1 photoconductor 3 transfer belt 4, 5 roller 8 power supply
───────────────────────────────────────────────────── フロントページの続き (72)発明者 兪 英雄 東京都大田区中馬込１丁目３番６号・株 式会社リコー内 (72)発明者 河石 康則 東京都大田区中馬込１丁目３番６号・株 式会社リコー内 (72)発明者 上山 英樹 東京都大田区中馬込１丁目３番６号・株 式会社リコー内 (72)発明者 本橋 俊昭 東京都大田区中馬込１丁目３番６号・株 式会社リコー内 (72)発明者 高橋 充 東京都大田区中馬込１丁目３番６号・株 式会社リコー内 (72)発明者 美才治 隆 東京都大田区中馬込１丁目３番６号・株 式会社リコー内 (56)参考文献 特開 平３−186876（ＪＰ，Ａ) 特開 平２−110586（ＪＰ，Ａ) (58)調査した分野(Int.Cl.7，ＤＢ名) G03G 15/16 G03G 15/01 114 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Hideo Yu 1-3-6 Nakamagome, Ota-ku, Tokyo, Ricoh Co., Ltd. (72) Inventor Yasunori Kawaishi 1-3-6 Nakamagome, Ota-ku, Tokyo Ricoh Co., Ltd. (72) Inventor Hideki Ueyama 1-3-6 Nakamagome, Ota-ku, Tokyo; Ricoh Co., Ltd. (72) Inventor Toshiaki Motobashi 1-3-6, Nakamagome, Ota-ku, Tokyo Ricoh Co., Ltd. (72) Inventor Mitsuru Takahashi 1-3-6 Nakamagome, Ota-ku, Tokyo, Japan Ricoh Co., Ltd. (72) Inventor Takashi Meishin 1-3-3 Nakamagome, Ota-ku, Tokyo No. 6, Ricoh Co., Ltd. (56) References JP-A-3-186876 (JP, A) JP-A-2-110586 (JP, A) (58) Fields investigated (Int. Cl. 7 , DB G03G 15/16 G03G 15/01 114
Claims (2)
体に対して所定のニップ幅をもって当接して移動し、前
記感光体上に形成されたトナー像が転写される被転写体
と、この被転写体に所定の転写バイアスを印加する転写
バイアス印加手段と、前記感光体に対して転写領域より
上流側であって、前記感光体と前記被転写体との接触開
始点までの領域で、前記被転写体に対し、前記トナー像
の前記感光体から前記被転写体への転移量が増大するご
とく前記転写バイアスに電位勾配を持たせる電位勾配生
成手段とを備え、電位勾配生成手段は定電圧素子を介し
て接地されている画像形成装置であって、前記転写バイ
アス印加手段は前記ニップ部に対して前記被転写体の移
動方向下流側で、前記被転写体と接触する電極であり、
前記電位勾配生成手段は前記ニップ部に対して前記被転
写体の移動方向上流側で、前記被転写体と接触する電極
であることを特徴とする画像形成装置。A photoreceptor on which a toner image is formed, and a transfer target on which the toner image formed on the photoreceptor is moved while being in contact with the photoreceptor with a predetermined nip width. A transfer bias applying unit for applying a predetermined transfer bias to the transfer object; and an area upstream of a transfer area with respect to the photoconductor and extending to a contact start point between the photoconductor and the transfer object. A potential gradient generating means for causing the transfer bias to have a potential gradient as the transfer amount of the toner image from the photoreceptor to the transfer target increases with respect to the transferred body; Is an image forming apparatus that is grounded via a constant voltage element.
Asbestos applying means moves the object to be transferred with respect to the nip portion.
On the downstream side in the moving direction, an electrode that comes into contact with the transfer object,
The potential gradient generating means is configured to rotate the nip with the
An electrode that is in contact with the object to be transferred on the upstream side in the moving direction of the object;
An image forming apparatus characterized in that.
記被転写体は、前記感光体に対して所定のニップ幅をも
って当接する転写ベルトに担持され搬送される転写紙で
あることを特徴とする画像形成装置。2. The image forming apparatus according to claim 1, wherein
The transfer object has a predetermined nip width with respect to the photoconductor.
Transfer paper carried and transported by the transfer belt
An image forming apparatus wherein there.
Priority Applications (7)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP01015993A JP3271811B2 (en) | 1992-04-09 | 1993-01-25 | Image forming device |
| ES93105767T ES2161701T3 (en) | 1992-04-09 | 1993-04-07 | IMAGE FORMATION DEVICE. |
| DE69330579T DE69330579T2 (en) | 1992-04-09 | 1993-04-07 | Image forming apparatus |
| EP93105767A EP0568829B1 (en) | 1992-04-09 | 1993-04-07 | Image forming apparatus |
| US08/044,032 US5461461A (en) | 1992-01-22 | 1993-04-08 | Image transferring device and medium separating device for an image forming apparatus |
| KR1019930005981A KR0145748B1 (en) | 1992-04-09 | 1993-04-09 | Image forming apparatus |
| US08/459,422 US5666622A (en) | 1992-01-22 | 1995-06-02 | Image transferring device and medium separating device for an image forming apparatus |
Applications Claiming Priority (5)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP8891692 | 1992-04-09 | ||
| JP4-88916 | 1992-04-10 | ||
| JP4-90701 | 1992-04-10 | ||
| JP9070192 | 1992-04-10 | ||
| JP01015993A JP3271811B2 (en) | 1992-04-09 | 1993-01-25 | Image forming device |
Related Child Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2001330893A Division JP2002139926A (en) | 1992-04-09 | 2001-10-29 | Image forming device |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH06167896A JPH06167896A (en) | 1994-06-14 |
| JP3271811B2 true JP3271811B2 (en) | 2002-04-08 |
Family
ID=27278864
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP01015993A Expired - Lifetime JP3271811B2 (en) | 1992-01-22 | 1993-01-25 | Image forming device |
Country Status (5)
| Country | Link |
|---|---|
| EP (1) | EP0568829B1 (en) |
| JP (1) | JP3271811B2 (en) |
| KR (1) | KR0145748B1 (en) |
| DE (1) | DE69330579T2 (en) |
| ES (1) | ES2161701T3 (en) |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP3488328B2 (en) * | 1996-02-02 | 2004-01-19 | 株式会社リコー | Transfer belt device |
| JP3306310B2 (en) * | 1996-08-29 | 2002-07-24 | シャープ株式会社 | Image forming device |
| JP2004109706A (en) | 2002-09-19 | 2004-04-08 | Ricoh Co Ltd | Belt driving device, transfer driving system, and image forming apparatus |
| JP2006047707A (en) * | 2004-08-05 | 2006-02-16 | Ricoh Co Ltd | Image forming method and image forming apparatus |
| JP5564993B2 (en) * | 2010-03-01 | 2014-08-06 | 株式会社リコー | Image forming apparatus |
Family Cites Families (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS58111960A (en) * | 1981-12-25 | 1983-07-04 | Ricoh Co Ltd | Transfer paper separating device |
| JPH0623900B2 (en) * | 1986-03-03 | 1994-03-30 | ヤマウチ株式会社 | Transfer belt used in image forming apparatus |
| US5172173A (en) * | 1988-09-01 | 1992-12-15 | Canon Kabushiki Kaisha | Image forming device and transfer belt having contact-type electricity feeding means |
| JPH02110586A (en) * | 1988-10-20 | 1990-04-23 | Canon Inc | Image forming device |
| DE68912889T2 (en) * | 1988-11-08 | 1994-08-25 | Canon Kk | Image forming apparatus with control means for the electrostatic attraction of transmission material. |
| JPH03186876A (en) * | 1989-12-16 | 1991-08-14 | Canon Inc | Image forming device |
-
1993
- 1993-01-25 JP JP01015993A patent/JP3271811B2/en not_active Expired - Lifetime
- 1993-04-07 EP EP93105767A patent/EP0568829B1/en not_active Expired - Lifetime
- 1993-04-07 DE DE69330579T patent/DE69330579T2/en not_active Expired - Lifetime
- 1993-04-07 ES ES93105767T patent/ES2161701T3/en not_active Expired - Lifetime
- 1993-04-09 KR KR1019930005981A patent/KR0145748B1/en not_active IP Right Cessation
Also Published As
| Publication number | Publication date |
|---|---|
| KR930022160A (en) | 1993-11-23 |
| KR0145748B1 (en) | 1998-09-15 |
| DE69330579T2 (en) | 2002-06-27 |
| EP0568829A2 (en) | 1993-11-10 |
| JPH06167896A (en) | 1994-06-14 |
| EP0568829B1 (en) | 2001-08-16 |
| ES2161701T3 (en) | 2001-12-16 |
| DE69330579D1 (en) | 2001-09-20 |
| EP0568829A3 (en) | 1995-05-10 |
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