JPH11133812A - Image forming device - Google Patents

Image forming device

Info

Publication number
JPH11133812A
JPH11133812A JP9314326A JP31432697A JPH11133812A JP H11133812 A JPH11133812 A JP H11133812A JP 9314326 A JP9314326 A JP 9314326A JP 31432697 A JP31432697 A JP 31432697A JP H11133812 A JPH11133812 A JP H11133812A
Authority
JP
Japan
Prior art keywords
transfer
image
exposure
toner image
toner
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.)
Granted
Application number
JP9314326A
Other languages
Japanese (ja)
Other versions
JP3576776B2 (en
Inventor
Tooru Kuzumi
徹 葛見
Original Assignee
Canon Inc
キヤノン株式会社
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Canon Inc, キヤノン株式会社 filed Critical Canon Inc
Priority to JP31432697A priority Critical patent/JP3576776B2/en
Publication of JPH11133812A publication Critical patent/JPH11133812A/en
Application granted granted Critical
Publication of JP3576776B2 publication Critical patent/JP3576776B2/en
Anticipated expiration legal-status Critical
Expired - Fee Related legal-status Critical Current

Links

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device provided with pre-transfer exposing means capable of preventing the toner image form scattering in the case of transferring the toner image on a second surface at the both-surface print processing stage. SOLUTION: This device is allowed to magnify potential difference by setting a light quantity of the pre-transfer exposure at L2 (=0.2 Lux.sec) at the front side time, and at L3 (=0.12 Lux.sec) at the rear side time, and selecting potential difference between the back ground part potential Vd3 (= 250 V) at the rear side time and the toner part potential Vt to be 150 V. Therefore, the binding force of the toner image is strengthened, and scatter can be prevented.

Description

【発明の詳細な説明】DETAILED DESCRIPTION OF THE INVENTION
【0001】[0001]
【発明の属する技術分野】本発明は、反転現像方式によ
る電子写真方式を利用した複写機やプリンター等の画像
形成装置に関するものである。
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as a copying machine or a printer using an electrophotographic system based on a reversal developing system.
【0002】[0002]
【従来の技術】電子写真方式を利用したデジタル複写機
やプリンター等においては反転現像方式が多く用いられ
る。反転現像方式では、一様に帯電した感光体面に対し
レーザービーム、LED等により記録すべき画像情報に
対応した画像露光を行って静電潜像を形成し、その際に
露光を受けて電位の低下した部分に感光体の帯電極性と
同極性に帯電したトナーを付着させてトナー像を形成す
る。ついで、トナー像に当接させた転写紙の背面にトナ
ーと逆極性の転写電荷を付与し転写紙上にトナーを転写
する。
2. Description of the Related Art In a digital copying machine, a printer or the like utilizing an electrophotographic system, a reversal developing system is often used. In the reversal developing method, a uniformly charged photoreceptor surface is exposed to an image corresponding to image information to be recorded by a laser beam, an LED, or the like to form an electrostatic latent image. A toner charged to the same polarity as the charge polarity of the photoreceptor is attached to the lowered portion to form a toner image. Next, a transfer charge having a polarity opposite to that of the toner is applied to the back surface of the transfer paper that has been brought into contact with the toner image, and the toner is transferred onto the transfer paper.
【0003】このとき、転写紙は感光体と逆極性に帯電
するため転写紙と感光体面の間に静電吸着力が発生し、
その後の感光体からの転写紙の分離が行いにくくなる。
特に背景部すなわち非画像露光部は感光体電位が高いた
め、背景部に対応する部分の転写紙背面には多くの転写
電荷が流入して転写紙の帯電電位が上がり、静電吸着力
も強くなる。
At this time, since the transfer paper is charged to the opposite polarity to the photoconductor, an electrostatic attraction force is generated between the transfer paper and the photoconductor surface,
Then, it becomes difficult to separate the transfer paper from the photoconductor.
In particular, the background portion, that is, the non-image exposed portion has a high photoconductor potential, so that a large amount of transfer charge flows into the back surface of the transfer sheet corresponding to the background portion to increase the charge potential of the transfer sheet and increase the electrostatic attraction force. .
【0004】そこで、転写工程の前にLED等の露光手
段により感光体面を一様に露光し、背景部電位を低下さ
せ、転写時に発生する静電吸着力を弱めることで分離を
行いしやすくしている。
Therefore, before the transfer step, the surface of the photoreceptor is uniformly exposed by an exposure means such as an LED to lower the potential of the background portion and weaken the electrostatic attraction force generated at the time of transfer to facilitate separation. ing.
【0005】[0005]
【発明が解決しようとする課題】しかしながら、転写前
露光を行うと、背景部とトナー像部の電位差が小さくな
るため、転写工程時にトナー像を形成するトナーの一部
が背景部側に飛び散りやすくなる。とくに、転写紙の表
裏の両面にプリント画像を形成する両面プリント時は、
おもて面(第1面)のトナー像を加熱定着してプリント
画像を形成したのち、裏面(第2面)にトナー像を転写
する際の飛び散りが顕著で、画像品位を低下させてい
た。この様子を図8〜図10に示す。
However, when the pre-transfer exposure is performed, the potential difference between the background portion and the toner image portion becomes small, so that a part of the toner forming the toner image in the transfer step is easily scattered to the background portion side. Become. Especially, when printing on both sides of the transfer paper,
After heat-fixing the toner image on the front surface (first surface) to form a print image, scattering when transferring the toner image to the back surface (second surface) is remarkable, deteriorating the image quality. . This situation is shown in FIGS.
【0006】図8は画像形成プロセスにおける感光体の
電位を示したものである。まず、感光体をVd1に一様
に帯電した後、トナー像を形成すべき部分に露光Eを行
い電位をVsに低下させ静電潜像を形成する(a)。つ
いで、感光体と同極性に帯電したトナーを用いて反転現
像を行いVs部にトナーを付着させてトナー像Tを形成
する(b)。トナー像Tはトナー保有電荷により電位V
tを有する。このトナー像Tを担持した感光体に対し転
写前露光Pを行い背景部電位をVd2(>Vt)に低下
させる。一方、トナー像部はトナーにより露光Pが遮蔽
されるため感光体電位は低下せず、また、露光後もトナ
ー保有電荷は変化しないためトナー像部の電位Vtは変
化しない(c)。
FIG. 8 shows the potential of the photosensitive member in the image forming process. First, after uniformly charging the photoreceptor to Vd1, exposure E is performed on a portion where a toner image is to be formed to lower the potential to Vs to form an electrostatic latent image (a). Next, reversal development is performed using a toner charged to the same polarity as that of the photoconductor, and the toner is attached to the Vs portion to form a toner image T (b). The toner image T has a potential V
t. The pre-transfer exposure P is performed on the photoreceptor carrying the toner image T to lower the background potential to Vd2 (> Vt). On the other hand, in the toner image portion, the exposure P is shielded by the toner, so that the photoconductor potential does not decrease, and the charge Vt of the toner image portion does not change even after the exposure because the toner holding charge does not change (c).
【0007】トナー像Tは背景部とトナー像境界の電位
差にもとづく静電気力を受けて感光体上に拘束される。
電位図(b)においてトナー像Tが感光体上に拘束され
る様子を(b’)に示す。トナー像Tと背景部の境界に
は電位差Vd1−Vtにもとづく電気力線e1が生じて
おり、トナー像Tは電気力線e1に沿って静電気力を受
け、Vs部に拘束される。電位差Vd1−Vtが大きい
ほど静電気力が大きくトナー像Tは強く拘束される。一
方、電位図(c)では、電位差Vd2−Vtが小さいた
め(c’)に示すように電気力線の数が減り静電気力も
小さくなる。このため拘束力も弱く飛び散りやすい。
The toner image T is restrained on the photosensitive member by receiving an electrostatic force based on a potential difference between the background portion and the boundary of the toner image.
(B ′) shows how the toner image T is restrained on the photoconductor in the potential diagram (b). At the boundary between the toner image T and the background portion, a line of electric force e1 is generated based on the potential difference Vd1-Vt, and the toner image T receives an electrostatic force along the line of electric force e1 and is restrained by the Vs portion. As the potential difference Vd1-Vt is larger, the electrostatic force is larger and the toner image T is more strongly restrained. On the other hand, in the potential diagram (c), since the potential difference Vd2-Vt is small, the number of lines of electric force decreases and the electrostatic force also decreases as shown in (c '). For this reason, the binding force is weak and it is easy to fly.
【0008】ところで、図9は、加熱定着により転写紙
が変形する様子を示したもので、定着前にほぼストレー
トであった転写紙10は、加熱圧接された2本のローラ
11a、11bで構成した定着手段11を通過すること
で波打ち状の変形10’を生じる。これは、定着前に転
写紙に含まれていた水分が加熱により蒸発する際、転写
紙全域に均一に熱が伝わらず、水分が蒸発した部分と残
存した部分で紙繊維の伸縮度合いが異なるために生じ
る。
FIG. 9 shows a state in which the transfer paper is deformed by the heat fixing. The transfer paper 10, which was almost straight before the fixing, is composed of two rollers 11a and 11b which are heated and pressed. When the sheet passes through the fixing means 11, a wavy deformation 10 ′ is generated. This is because when moisture contained in the transfer paper before fixing is evaporated by heating, heat is not uniformly transmitted to the entire area of the transfer paper, and the degree of expansion and contraction of the paper fiber is different between the portion where the moisture has evaporated and the remaining portion. Occurs.
【0009】図10(a)は、このように波打ちを生じ
た転写紙にトナー像が転写される様子を示したものであ
る。
FIG. 10A shows a state in which a toner image is transferred onto a transfer sheet having such waving.
【0010】転写紙10は不図示の紙搬送部材により感
光体1に当接するように搬入され、転写紙背面に転写コ
ロナ帯電器6からのコロナ電荷が付与される。トナー像
Tはコロナ電荷による電界からの引力を受けて転写紙上
に転写する。領域θはコロナ電荷が付与される範囲を示
しており、転写紙が領域θを通過中、コロナ電荷が転写
紙背面に徐々に蓄積されると同時に転写紙と感光体間の
静電吸着力が増大していく。トナー像が感光体上に強く
拘束されている場合、拘束力に打ち勝ってトナーを転写
するだけの十分量の電荷が蓄積した時点で転写が行われ
る。このため転写紙と感光体間に強い静電吸着力が生じ
ており、波打ちを持つ転写紙であっても、転写紙は感光
体面に沿った形状で感光体に密着し、転写紙と感光体に
挟まれたトナーは飛び散ることなく転写する。
The transfer paper 10 is carried in by a paper transport member (not shown) so as to be in contact with the photoreceptor 1, and corona charges from the transfer corona charger 6 are applied to the back of the transfer paper. The toner image T is transferred onto transfer paper by receiving an attractive force from an electric field due to corona charges. The area θ indicates the area where the corona charge is applied, and while the transfer paper is passing through the area θ, the corona charge is gradually accumulated on the back of the transfer paper, and at the same time, the electrostatic attraction force between the transfer paper and the photoconductor is reduced. It increases. When the toner image is strongly constrained on the photoreceptor, the transfer is performed when a sufficient amount of electric charge is accumulated to overcome the constraining force and transfer the toner. For this reason, a strong electrostatic attraction force is generated between the transfer paper and the photoconductor, and even if the transfer paper has a wavy shape, the transfer paper adheres to the photoconductor in a shape along the surface of the photoconductor, and the transfer paper and the photoconductor are Is transferred without scattering.
【0011】一方、転写前露光を受けて拘束力が低下し
たトナー像は、わずかなコロナ電荷による電界からも力
を受けて転写する。このため、領域θの上流域で転写紙
背面に少量のコロナ電荷が付与された時点でトナー像が
転写し、また、静電吸着力が弱いため、図10(b)に
示すように、波打ちで生じた凹部Aでは感光体と転写紙
が密着せず、トナー像はコロナ電荷の蓄積量が多い下流
側に引かれて飛び散りを生じていた。
On the other hand, the toner image whose binding force has been reduced by the pre-transfer exposure is transferred by receiving a force from an electric field due to a slight corona charge. Therefore, the toner image is transferred when a small amount of corona charge is applied to the back surface of the transfer paper in the upstream area of the area θ, and the electrostatic attraction force is weak. In the concave portion A generated in step (1), the photoconductor and the transfer paper did not adhere to each other, and the toner image was drawn to the downstream side where the corona charge accumulation amount was large, and scattered.
【0012】従って、本発明の目的は、両面プリント工
程時に第2面へのトナー像の転写の際にトナー像の飛び
散りを防止することのできる、転写前露光手段を有する
画像形成装置を提供することである。
Accordingly, an object of the present invention is to provide an image forming apparatus having a pre-transfer exposure means capable of preventing the toner image from scattering when transferring the toner image to the second surface in a double-sided printing process. That is.
【0013】[0013]
【課題を解決するための手段】上記目的は本発明に係る
画像形成装置にて達成される。要約すれば、本発明は、
像担持体上に形成した静電潜像を現像剤により反転現像
して現像剤像とし、該現像剤像を転写材上に転写する前
に現像剤像を担持した像担持体面を露光する転写前露光
を行った後、転写、定着をへてプリント画像を得る画像
形成装置において、転写材の第1面にプリントした後、
同転写材の第2面にプリントを行う際に前記転写前露光
時の露光量を切り換えることを特徴とする画像形成装置
である。
The above object is achieved by an image forming apparatus according to the present invention. In summary, the present invention provides:
A transfer that reversely develops the electrostatic latent image formed on the image carrier with a developer to form a developer image, and exposes the image carrier surface carrying the developer image before transferring the developer image onto a transfer material. After performing pre-exposure, in an image forming apparatus that obtains a print image by transferring and fixing, after printing on the first surface of the transfer material,
An image forming apparatus characterized in that the exposure amount at the time of the pre-transfer exposure is switched when printing is performed on the second surface of the transfer material.
【0014】第2面プリント時は、第1面プリント時よ
り転写前露光の露光量を小さくするか、もしくは、露光
をオフすることが好ましい。
It is preferable that the amount of exposure before transfer is smaller or the exposure is turned off during the second-side printing than during the first-side printing.
【0015】本発明による他の態様によれば、像担持体
上に形成した静電潜像を現像剤により反転現像して現像
剤像とし、該現像剤像を転写材上に転写する前に現像剤
像を担持した像担持体面を露光する転写前露光を行った
後、転写、定着をへてプリント画像を得る画像形成装置
において、転写材上の現像剤像の占有面積率に応じて転
写前露光の露光量を切り換えることを特徴とする画像形
成装置が提供される。
According to another aspect of the present invention, the electrostatic latent image formed on the image carrier is reversely developed with a developer to form a developer image, and before the developer image is transferred onto a transfer material, In an image forming apparatus that performs a pre-transfer exposure that exposes an image carrier surface that carries a developer image, and then performs a transfer and a fixation to obtain a print image, the transfer is performed according to an occupied area ratio of the developer image on the transfer material. An image forming apparatus is provided, wherein the amount of pre-exposure is switched.
【0016】前記占有面積率が10%以上のとき、前記
転写前露光の露光量を小さくするか、もしくは、露光を
オフすることが好ましい。前記転写を行う転写手段は、
転写材を前記像担持体に圧接する弾性体であることが好
ましい。
When the occupied area ratio is 10% or more, it is preferable to reduce the exposure amount of the pre-transfer exposure or to turn off the exposure. The transfer means for performing the transfer,
It is preferable that the transfer material is an elastic body that presses the image carrier against the image carrier.
【0017】[0017]
【発明の実施の形態】以下、本発明に係る画像形成装置
を図面に則して更に詳しく説明する。
DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an image forming apparatus according to the present invention will be described in more detail with reference to the drawings.
【0018】実施例1 本発明の実施例1について図1および図2により説明す
る。
Embodiment 1 Embodiment 1 of the present invention will be described with reference to FIGS.
【0019】まず図2により、本実施例の画像形成装置
について説明する。同図において、像担持体である感光
体1は、円筒状の導電基体上にアモルファスシリコン等
の光導電層を設けたもので図中の矢印方向に回転可動に
軸支されている。感光体1は、周知のコロトロン帯電器
2により所定の電位(400〜500V)に一様に帯電
された後、画像信号に応じて変調されたレーザービーム
露光3を受け静電潜像が形成される。レーザービーム3
はレーザーダイオード31から発し回転するポリゴンミ
ラー32、ミラー33を介して感光体1に走査照射され
る。
First, the image forming apparatus of this embodiment will be described with reference to FIG. In FIG. 1, a photoreceptor 1 serving as an image carrier has a photoconductive layer such as amorphous silicon provided on a cylindrical conductive substrate, and is rotatably supported in the direction of the arrow in the drawing. The photoreceptor 1 is uniformly charged to a predetermined potential (400 to 500 V) by a well-known corotron charger 2, and then receives a laser beam exposure 3 modulated according to an image signal to form an electrostatic latent image. You. Laser beam 3
Is irradiated on the photosensitive member 1 through a polygon mirror 32 and a mirror 33 which are emitted from a laser diode 31 and rotate.
【0020】ついで、この静電潜像に対しトナーを収納
した現像装置4により現像を行い、感光体1上にトナー
像が形成される。つづいて、転写工程に先立ち、トナー
像が担持した感光体面に対し発光ダイオード(LED)
等を用いた転写前露光装置5による露光が行われる。
Next, the electrostatic latent image is developed by a developing device 4 containing toner, and a toner image is formed on the photoreceptor 1. Next, prior to the transfer process, a light emitting diode (LED) is applied to the photoreceptor surface carrying the toner image.
Exposure is performed by the pre-transfer exposure device 5 using the method described above.
【0021】このあと、トナー像は転写紙収納部12か
ら搬送路に沿って給紙された転写材たる転写紙10上に
転写手段である転写コロナ帯電器6により転写されたの
ち、分離コロナ帯電器7により感光体1から分離され
て、定着装置11へと送られ、転写紙上のトナー像が永
久定着されてプリント画像が得られる。転写紙のおもて
面のみにプリントする場合、定着を終えた転写紙は排出
部14へと排出される。転写工程を終えた後、感光体1
はそのまま回転しクリーニング装置8により感光体表面
の残留トナーが除去され、さらに消去ランプ9により感
光体1の残留電荷が消去されて次回の画像形成が行われ
る。
After that, the toner image is transferred from a transfer paper storage section 12 onto a transfer paper 10 as a transfer material fed along a transport path by a transfer corona charger 6 serving as a transfer means, and then a separation corona charger. The toner image is separated from the photoreceptor 1 by the device 7 and sent to the fixing device 11, where the toner image on the transfer paper is permanently fixed to obtain a print image. When printing is performed only on the front side of the transfer paper, the transfer paper after fixing is discharged to the discharge unit 14. After the transfer step, the photoconductor 1
Is rotated as it is, the residual toner on the surface of the photoreceptor is removed by the cleaning device 8, and the residual charge on the photoreceptor 1 is erased by the erase lamp 9, so that the next image formation is performed.
【0022】両面プリント時は、おもて面(第1面)の
定着を終えたのち転写紙10は搬送路13を通り再び転
写部に搬送され、裏面(第2面)にトナー像を転写した
後、分離、定着をへて排出されプリント工程を終了す
る。
At the time of double-sided printing, after the fixing of the front side (first side) is completed, the transfer paper 10 is again conveyed to the transfer section through the conveyance path 13 and the toner image is transferred to the back side (second side). After that, the sheet is separated and fixed and discharged, and the printing process is completed.
【0023】つぎに図1により本発明の特徴部分につい
て説明する。図1(a)は、転写前露光の光量(感光体
面上での光量)と背景部電位Vd(転写位置での電位)
の関係を表したものである。転写前露光を受けない場
合、すなわち光量ゼロの場合、背景部電位は最大で、光
量が大きいほど電位は低くなる。
Next, the features of the present invention will be described with reference to FIG. FIG. 1A shows the light amount of the pre-transfer exposure (light amount on the photoreceptor surface) and the background portion potential Vd (potential at the transfer position).
It expresses the relationship. When the pre-transfer exposure is not performed, that is, when the light amount is zero, the background portion potential is maximum, and the potential decreases as the light amount increases.
【0024】図1(b)は、分離コロナ帯電器の出力電
流(分離電流)と背景部電位Vdの関係を表したもので
ある。電流が低いと、転写紙背面の転写電荷が十分に除
電されず転写紙が感光体から分離されずに分離不良を起
こす。この領域を(b)のIに示す。また、電流が高い
と、転写と逆極性、すなわちトナーと同極性の分離電荷
が過剰に付与され、トナーが分離電荷に反発して感光体
側に戻る再転写が発生する。この領域をIIに示す。
FIG. 1B shows the relationship between the output current (separation current) of the separation corona charger and the background potential Vd. If the current is low, the transfer charges on the back surface of the transfer paper are not sufficiently removed, and the transfer paper is not separated from the photoreceptor, causing separation failure. This region is indicated by I in (b). Also, when the current is high, the separated charge having the opposite polarity to the transfer, that is, the same polarity as the toner is excessively applied, and retransfer occurs in which the toner repels the separated charge and returns to the photoconductor side. This region is shown in II.
【0025】上記の領域IとIIに挟まれた部分が適正領
域である。適正領域の広さは背景部電位が高いほど狭く
なる。これは前述したように、背景部電位が高いほど転
写時に多くの転写電荷が付与され、これを除電するのに
高い電流を必要とするからである。
The portion sandwiched between the regions I and II is a proper region. The area of the appropriate area becomes narrower as the background potential increases. This is because, as described above, as the background portion potential is higher, more transfer charge is applied during transfer, and a higher current is required to remove the charge.
【0026】従来は、おもて面および裏面プリントとも
に光量をL2(=0.2Lux・sec)に設定し、背
景部電位をVd2(=150V)に低下させた。このと
き適正領域の広さはh(=260μA)である。分離電
流値は適正領域の中心付近のi0に設定する。分離電流
の経時変化や転写紙特性の環境変動を調べた結果、安定
して分離を行うためには適正領域が少なくとも200μ
A必要であることがわかった。従来は、この適正領域が
十分確保されていた。しかしながら、感光体上の潜像は
fに示すように背景部電位Vd2とトナー像部電位Vt
(=100V)の電位差が50Vとなり、電位差が小さ
いためトナー像の拘束力が弱くなり上述した理由により
裏面の転写時にトナー像飛び散りを生じていた。
Conventionally, the light amount is set to L2 (= 0.2 Lux · sec) for both the front and back prints, and the background potential is reduced to Vd2 (= 150 V). At this time, the area of the appropriate area is h (= 260 μA). The separation current value is set to i0 near the center of the appropriate region. As a result of examining the secular change of the separation current and the environmental fluctuation of the transfer paper characteristics, an appropriate area of at least 200 μm was required for stable separation.
A It turned out to be necessary. Conventionally, this appropriate area has been sufficiently ensured. However, as shown by f, the latent image on the photoreceptor has a background portion potential Vd2 and a toner image portion potential Vt.
(= 100 V), the potential difference was 50 V, and the potential difference was small, so that the binding force of the toner image was weakened and the toner image was scattered during the transfer on the back surface for the above-described reason.
【0027】本実施例では、おもて面時の光量は従来ど
おりL2に設定し、裏面時の光量をL3(=0.12L
ux・sec)に設定するようにした。これにより、裏
面時の背景部電位はVd3(=250V)となり、潜像
はgに示すように、背景部電位Vd3とトナー像部電位
Vtの電位差が150Vとなって電位差が拡大しトナー
像の拘束力が強まり、飛び散りを生じなかった。
In this embodiment, the light quantity at the front side is set to L2 as before, and the light quantity at the back side is set to L3 (= 0.12L).
ux · sec). As a result, the potential of the background portion on the back side becomes Vd3 (= 250 V), and the potential difference between the background portion potential Vd3 and the toner image portion potential Vt becomes 150 V, as shown by g, so that the potential difference is enlarged and the toner image The binding force increased, and no splattering occurred.
【0028】また、このとき、適正領域の広さはj(=
205μA)で、必要量200μAが確保されている。
すなわち、転写前露光の光量を適正に切り換えること
で、飛び散りを防止するとともに安定した分離を行うこ
とができた。
At this time, the size of the appropriate area is j (=
205 μA), and the required amount of 200 μA is secured.
That is, by appropriately switching the light amount of the pre-transfer exposure, scattering could be prevented and stable separation could be performed.
【0029】上記光量の設定値は使用する感光体の帯電
電位やトナーの種類に応じて、適宜、最適値に設定す
る。本実施例では、アモルファスシリコン感光体および
磁性一成分トナーを使用した装置を用いて、電位差と飛
び散りの有無を調べたところ、電位差が100V以上の
とき飛び散りはなくなり、これより電位変動分を考慮し
て電位差150Vとなるよう光量を設定した。
The set value of the light quantity is appropriately set to an optimum value according to the charging potential of the photosensitive member used and the type of toner. In the present embodiment, the potential difference and the presence or absence of scattering were examined using an apparatus using an amorphous silicon photoreceptor and a magnetic one-component toner. When the potential difference was 100 V or more, the scattering was eliminated, and the potential fluctuation was taken into consideration. The light amount was set so that the potential difference was 150 V.
【0030】実施例2 つぎに、本発明の実施例2について図3〜図5により説
明する。本実施例においては、両面プリント時に、プリ
ント画像の種類に応じて転写前露光の光量を切り換える
ようにした。
Second Embodiment Next, a second embodiment of the present invention will be described with reference to FIGS. In the present embodiment, during double-sided printing, the amount of light for pre-transfer exposure is switched according to the type of print image.
【0031】図1と同様、図3(a)は光量と背景部電
位の関係を示し、図3(b)は分離電流の適正領域を示
す。(b)において、III は、プリント画像のトナー像
面積率(転写紙1枚の面積中でトナー像部が占める面積
比率すなわち占有面積率)が小さい場合の分離不良およ
び再転写領域を示し、IVはトナー像面積率が大きい場合
の分離不良および再転写領域を示す。
As in FIG. 1, FIG. 3 (a) shows the relationship between the light quantity and the background potential, and FIG. 3 (b) shows the proper region of the separation current. In (b), III indicates a separation failure and a retransfer area when the toner image area ratio of the print image (the area ratio occupied by the toner image portion in one transfer sheet area, that is, the occupied area ratio) is small. Indicates poor separation and retransfer area when the toner image area ratio is large.
【0032】前述のように、静電吸着力は背景部で強
く、よって、トナー像面積率が大きいほど、すなわち、
背景部面積が小さいほど転写紙全体が受ける吸着力は下
がり分離しやすくなる。従って、トナー像面積率の大き
いIVは面積率が小さいIII より分離不良側の適正領域が
広がる。
As described above, the electrostatic attraction force is strong in the background portion, and therefore, as the toner image area ratio increases, that is,
The smaller the area of the background portion, the lower the suction force applied to the entire transfer paper, and the easier it is to separate. Accordingly, an IV having a large toner image area ratio has a wider suitable area on the side of poor separation than a III having a small area ratio.
【0033】一方、トナー像面積率が大きいほど、すな
わち画像を構成するトナー粒子の個数が多いほど、そこ
に含まれる再転写しやすい特性を持つトナー粒子の割合
が増え、再転写しやすくなる傾向がある。従って、トナ
ー像面積率の大きいIVは面積率が小さいIII より再転写
側の適正領域が狭くなる。図3では、IVはトナー像面積
率10%以上の領域を示し、III はトナー像面積率5%
未満の領域を示す。
On the other hand, as the toner image area ratio increases, that is, as the number of toner particles constituting an image increases, the proportion of toner particles having retransferable characteristics included therein increases, and retransfer tends to occur. There is. Therefore, an IV having a large toner image area ratio has a smaller appropriate area on the retransfer side than a III having a small area ratio. In FIG. 3, IV indicates a region having a toner image area ratio of 10% or more, and III indicates a toner image area ratio of 5%.
Indicates the area less than.
【0034】まず、トナー像面積率が10%未満の場合
は、実施例1と同様に、裏面時の光量をL3に設定す
る。このとき適正領域の広さは少なくともh以上であ
り、分離電流i1に設定する。
First, when the toner image area ratio is less than 10%, the light amount on the back side is set to L3 as in the first embodiment. At this time, the width of the appropriate region is at least h or more, and is set to the separation current i1.
【0035】つぎに、同じくトナー像面積率が10%未
満の場合に、光量ゼロ、すなわち露光をオフし背景部電
位をVd1とすると適正領域の広さは最小でk(=15
0μA)となり必要量200μAを確保できない。これ
に対しトナー像面積率が10%以上であれば背景部電位
がVd1でも適正領域はm(=200μA)となり必要
量を確保できる。
Next, when the toner image area ratio is less than 10%, if the light amount is zero, that is, if the exposure is turned off and the background portion potential is set to Vd1, the width of the appropriate region is at least k (= 15).
0 μA), and the required amount of 200 μA cannot be secured. On the other hand, if the toner image area ratio is 10% or more, the appropriate area is m (= 200 μA) even when the background potential is Vd1, and the necessary amount can be secured.
【0036】従って、トナー像面積率が10%以上の画
像においては、裏面時の露光をオフすることで、より確
実に飛び散りを抑えるとともに分離も安定に行うことが
できた。このとき分離電流は最適値i2に切り換える。
とくに裏面時の飛び散りが視覚的に顕著になるのは、ト
ナー像面積率の高い写真や絵画像の、いわゆるベタ部で
あって、このような画像に対しては、微少な飛び散りも
抑えるべく、潜像の電位差を大きくすることが望まし
い。
Therefore, in the case of an image having a toner image area ratio of 10% or more, by turning off the exposure on the back side, scattering can be suppressed more reliably and separation can be performed stably. At this time, the separation current is switched to the optimum value i2.
In particular, the scattering on the back side is visually remarkable in a so-called solid portion of a photograph or a picture image having a high toner image area ratio, and for such an image, in order to suppress minute scattering, It is desirable to increase the potential difference of the latent image.
【0037】なお、トナー像面積率は、装置の操作パネ
ル上に設けた画像選択キーから入力するか、もしくは装
置付属の原稿リーダーや装置外部から入力された画像信
号をもとに算出する。
The toner image area ratio is input from an image selection key provided on the operation panel of the apparatus, or is calculated based on an image signal input from a document reader attached to the apparatus or from outside the apparatus.
【0038】ここでトナー像面積率の算出について図4
の装置のブロック図を参照して説明する。
FIG. 4 shows the calculation of the toner image area ratio.
A description will be given with reference to the block diagram of the device.
【0039】原稿リーダー41が原稿を微小セルに分割
し、セル毎に画像の有無を読みとって2値の電気信号
(画像信号)を出力する。画像信号はメモリ42に格納
されたのち、セル単位で順次、判定部43に送られる。
判定部43では送られた画像信号を積算し、セル総数に
対する画像存在セル数(トナー像面積率)を算出する。
A document reader 41 divides a document into minute cells, reads the presence or absence of an image for each cell, and outputs a binary electric signal (image signal). After the image signal is stored in the memory 42, the image signal is sequentially sent to the determination unit 43 in cell units.
The determination unit 43 integrates the transmitted image signals and calculates the number of image-existing cells (toner image area ratio) with respect to the total number of cells.
【0040】つづいて面積率が10%以上か否かを判定
し、判定結果に応じた判定信号を出力する。プリンター
45では判定信号にもとづき、転写前露光LEDの電圧
源および分離帯電器の高電圧源(いずれも不図示)の出
力を換えることで光量および電流が切り換えられ、プリ
ント動作が行われる。コンピュータやファクシミリ等、
外部から入力された画像信号に対しても同様な処理を行
う。また、操作パネル44から、原稿が高面積率である
ことを知らせるキー入力があると、ただちにプリンタ4
5の光量および電流は、面積率10%以上と同等設定が
なされ、プリント動作が行われる。
Subsequently, it is determined whether or not the area ratio is 10% or more, and a determination signal corresponding to the determination result is output. In the printer 45, the amount of light and the current are switched by changing the output of the voltage source of the pre-transfer exposure LED and the output of the high voltage source (both not shown) of the separation charger based on the determination signal, and the printing operation is performed. Computers and facsimile machines,
Similar processing is performed on an image signal input from the outside. Also, if there is a key input from the operation panel 44 indicating that the document has a high area ratio, the printer 4
The light amount and the current of No. 5 are set to be equivalent to the area ratio of 10% or more, and the printing operation is performed.
【0041】つぎに、トナー像面積率にもとづいた光量
切り換えフローについて主に図5により説明する。
Next, the flow of light quantity switching based on the toner image area ratio will be described mainly with reference to FIG.
【0042】まず、裏面プリントか否かを判断し(S
1)、裏面でない場合、すなわちおもて面の場合には光
量L2、分離電流i0に設定し(S2)、プリントを開
始する(S7)。S1にて裏面プリントの場合には、写
真モードか否かを判断し(S3)、写真モードと判断さ
れたときには露光をオフし、分離電流i2に設定し(S
4)、プリントを開始する(S7)。
First, it is determined whether or not the printing is the back side printing (S
1) If it is not the back side, that is, if it is the front side, the light amount L2 and the separation current i0 are set (S2), and printing is started (S7). In the case of the back side printing in S1, it is determined whether or not the photograph mode is set (S3). When the photograph mode is determined, the exposure is turned off and the separation current i2 is set (S3).
4) Printing is started (S7).
【0043】S3にて写真モードでないと判断した場合
には、トナー像面積率≧10%を上記の要領で判定する
(S5)。トナー像面積率≧10%の場合には上記のよ
うに露光をオフし、分離電流i2に設定し(S4)、プ
リントを開始する(S7)。
If it is determined in S3 that the mode is not the photograph mode, the toner image area ratio ≧ 10% is determined in the above manner (S5). When the toner image area ratio ≧ 10%, the exposure is turned off as described above, the separation current i2 is set (S4), and printing is started (S7).
【0044】S5にてトナー像面積率<10%の場合に
は、光量L3、分離電流i1に設定し、プリントを行う
(S7)。
If the toner image area ratio is less than 10% in S5, the light amount L3 and the separation current i1 are set, and printing is performed (S7).
【0045】なお、従来より写真原稿等に対し画像露光
レーザの発光タイミングを変更することで、その階調を
忠実にプリント再現する、いわゆる写真モードキーが設
けられることが多い。そこで上記の画像選択キーを、こ
れら写真モードキーと兼用させてもよい。また、上記で
は、トナー像面積率をもとに設定を切り換えたが、トナ
ー像の絶対面積をもとに切り換えてもよい。
It should be noted that a so-called photographic mode key has conventionally been provided, which changes the emission timing of an image exposure laser for a photographic original or the like so as to faithfully reproduce the gradation. Therefore, the above-mentioned image selection key may be used also as these photo mode keys. In the above description, the setting is switched based on the toner image area ratio. However, the setting may be switched based on the absolute area of the toner image.
【0046】実施例3 つぎに、本発明の実施例3について図6および図7によ
り説明する。上記実施例では、転写帯電器に周知のコロ
トロンを用いた場合を説明したが、転写ローラを用いる
ことで、裏面の飛び散りを確実に防止できる。図6は装
置の転写部を示したもので、転写帯電器として転写ロー
ラ15を用いる。図7は、転写ローラ15により、波打
ちを生じた転写紙10にトナー像Tが転写される様子を
示したものである。
Third Embodiment Next, a third embodiment of the present invention will be described with reference to FIGS. In the above embodiment, the case where a well-known corotron is used for the transfer charger has been described. However, the use of the transfer roller can surely prevent the back surface from scattering. FIG. 6 shows a transfer section of the apparatus, in which a transfer roller 15 is used as a transfer charger. FIG. 7 shows a state in which the transfer roller 15 transfers the toner image T to the transfer paper 10 having a wavy shape.
【0047】図7に示すように、転写ローラ15は導電
軸152の周囲に半導電性ゴムからなる弾性層151を
設けてなり、不図示の加圧手段により感光体1に圧接さ
れて変形し、転写ニップXを形成する。導電軸152に
は不図示の高圧電源が接続され、転写ニップX近傍の感
光体1と転写ローラ15間に転写電界を形成することで
トナー像が転写紙10に転写される。転写紙10は感光
体1と転写ローラ15に挟まれて通過するため、転写ニ
ップX、および、その近傍において、転写紙10に生じ
た波打ちが押しつぶされ、転写紙10と感光体1が密着
する。このため転写紙10と感光体10に挟まれたトナ
ーは飛び散りにくくなる。この効果と合わせ、上記の光
量切り換えを同時に行うことで、より裏面時の飛び散り
を効果的に抑えることができた。
As shown in FIG. 7, the transfer roller 15 is provided with an elastic layer 151 made of semiconductive rubber around a conductive shaft 152, and is deformed by being pressed against the photosensitive member 1 by a pressing means (not shown). Then, a transfer nip X is formed. A high-voltage power supply (not shown) is connected to the conductive shaft 152, and a toner image is transferred onto the transfer paper 10 by forming a transfer electric field between the photoconductor 1 and the transfer roller 15 near the transfer nip X. Since the transfer paper 10 passes between the photoconductor 1 and the transfer roller 15, the waving generated on the transfer paper 10 is crushed in the transfer nip X and in the vicinity thereof, and the transfer paper 10 and the photoconductor 1 come into close contact with each other. . For this reason, the toner sandwiched between the transfer paper 10 and the photoconductor 10 is less likely to scatter. In addition to this effect, by simultaneously performing the above light amount switching, the scattering on the back surface can be more effectively suppressed.
【0048】[0048]
【発明の効果】以上の説明から明らかなように、本発明
の画像形成装置によれば、転写材の第1面にプリントし
た後、同転写材の第2面にプリントを行う際に前記転写
前露光時の露光量を切り換えることにより、あるいは、
転写材上の現像剤像の占有面積率に応じて転写前露光の
露光量を切り換えることにより、両面プリント工程時に
第2面へのトナー像の転写の際にトナー像の飛び散りを
防止することができ、画像品位を向上させることがで
き、同時に転写材の分離も良好に行うことができる。
As is apparent from the above description, according to the image forming apparatus of the present invention, after printing on the first surface of the transfer material, the transfer is performed when printing is performed on the second surface of the transfer material. By switching the exposure amount during pre-exposure, or
By switching the exposure amount of the pre-transfer exposure according to the occupied area ratio of the developer image on the transfer material, it is possible to prevent the toner image from scattering when transferring the toner image to the second surface during the double-sided printing process. As a result, the image quality can be improved, and at the same time, the transfer material can be well separated.
【図面の簡単な説明】[Brief description of the drawings]
【図1】実施例1の転写前露光量と分離電流適正域の関
係を示す説明図である。
FIG. 1 is an explanatory diagram showing a relationship between a pre-transfer exposure amount and a proper separation current region in Example 1.
【図2】実施例1〜3の画像形成装置を示す概略構成図
である。
FIG. 2 is a schematic configuration diagram illustrating an image forming apparatus according to first to third embodiments.
【図3】実施例2の転写前露光量と分離電流適正域の関
係を示す説明図である。
FIG. 3 is an explanatory diagram showing a relationship between a pre-transfer exposure amount and a proper separation current region in Example 2.
【図4】実施例2の画像形成装置を示すブロック図であ
る。
FIG. 4 is a block diagram illustrating an image forming apparatus according to a second embodiment.
【図5】実施例2の転写工程を示すフローチャートであ
る。
FIG. 5 is a flowchart illustrating a transfer process according to a second embodiment.
【図6】実施例3の転写ローラを示す概略構成図であ
る。
FIG. 6 is a schematic configuration diagram illustrating a transfer roller according to a third embodiment.
【図7】実施例3の転写ローラの転写時を示す説明図で
ある。
FIG. 7 is an explanatory diagram illustrating a state of transfer performed by a transfer roller according to a third embodiment.
【図8】反転現像および転写前露光工程を説明するため
の電位図である。
FIG. 8 is a potential diagram for explaining a reversal development and a pre-transfer exposure step.
【図9】加熱定着による転写紙の変形を説明するための
説明図である。
FIG. 9 is an explanatory diagram for explaining deformation of transfer paper due to heat fixing.
【図10】従来の転写工程を説明するための詳細図であ
る。
FIG. 10 is a detailed view for explaining a conventional transfer step.
【符号の説明】[Explanation of symbols]
1 感光体(像担持体) 5 転写前露光装置 6 転写帯電器 7 分離帯電器 15 転写ローラ(転写手段) DESCRIPTION OF SYMBOLS 1 Photoreceptor (image carrier) 5 Exposure apparatus before transfer 6 Transfer charger 7 Separation charger 15 Transfer roller (transfer means)

Claims (5)

    【特許請求の範囲】[Claims]
  1. 【請求項1】 像担持体上に形成した静電潜像を現像剤
    により反転現像して現像剤像とし、該現像剤像を転写材
    上に転写する前に現像剤像を担持した像担持体面を露光
    する転写前露光を行った後、転写、定着をへてプリント
    画像を得る画像形成装置において、 転写材の第1面にプリントした後、同転写材の第2面に
    プリントを行う際に前記転写前露光時の露光量を切り換
    えることを特徴とする画像形成装置。
    1. An image carrier having an electrostatic latent image formed on an image carrier, which is reversely developed with a developer to form a developer image, and the developer image is carried before the developer image is transferred onto a transfer material. In an image forming apparatus that obtains a print image by performing pre-transfer exposure for exposing the body surface, and then transferring and fixing, when printing on the first surface of the transfer material and then printing on the second surface of the transfer material An image forming apparatus, wherein the exposure amount during the pre-transfer exposure is switched.
  2. 【請求項2】 第2面プリント時は、第1面プリント時
    より転写前露光の露光量を小さくするか、もしくは、露
    光をオフすることを特徴とする請求項1の画像形成装
    置。
    2. The image forming apparatus according to claim 1, wherein the exposure amount of the pre-transfer exposure is reduced or the exposure is turned off during the second-side printing compared to the first-side printing.
  3. 【請求項3】 像担持体上に形成した静電潜像を現像剤
    により反転現像して現像剤像とし、該現像剤像を転写材
    上に転写する前に現像剤像を担持した像担持体面を露光
    する転写前露光を行った後、転写、定着をへてプリント
    画像を得る画像形成装置において、 転写材上の現像剤像の占有面積率に応じて転写前露光の
    露光量を切り換えることを特徴とする画像形成装置。
    3. An image bearing device in which an electrostatic latent image formed on an image carrier is reversely developed with a developer to form a developer image, and the developer image is carried before the developer image is transferred onto a transfer material. In an image forming apparatus that obtains a printed image after performing pre-transfer exposure, which exposes the body surface, and then transfers and fixes, the exposure amount of pre-transfer exposure is switched according to the occupied area ratio of the developer image on the transfer material. An image forming apparatus comprising:
  4. 【請求項4】 前記占有面積率が10%以上のとき、前
    記転写前露光の露光量を小さくするか、もしくは、露光
    をオフすることを特徴とする請求項3の画像形成装置。
    4. The image forming apparatus according to claim 3, wherein when the occupied area ratio is 10% or more, the exposure amount of the pre-transfer exposure is reduced or the exposure is turned off.
  5. 【請求項5】 前記転写を行う転写手段は、転写材を前
    記像担持体に圧接する弾性体であることを特徴とする請
    求項1から4のいずれかの項に記載の画像形成装置。
    5. The image forming apparatus according to claim 1, wherein the transfer unit that performs the transfer is an elastic body that presses a transfer material against the image carrier.
JP31432697A 1997-10-30 1997-10-30 Image forming device Expired - Fee Related JP3576776B2 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP31432697A JP3576776B2 (en) 1997-10-30 1997-10-30 Image forming device

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP31432697A JP3576776B2 (en) 1997-10-30 1997-10-30 Image forming device

Publications (2)

Publication Number Publication Date
JPH11133812A true JPH11133812A (en) 1999-05-21
JP3576776B2 JP3576776B2 (en) 2004-10-13

Family

ID=18051996

Family Applications (1)

Application Number Title Priority Date Filing Date
JP31432697A Expired - Fee Related JP3576776B2 (en) 1997-10-30 1997-10-30 Image forming device

Country Status (1)

Country Link
JP (1) JP3576776B2 (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2014002181A (en) * 2012-06-15 2014-01-09 Canon Inc Image forming apparatus

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2014002181A (en) * 2012-06-15 2014-01-09 Canon Inc Image forming apparatus

Also Published As

Publication number Publication date
JP3576776B2 (en) 2004-10-13

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