JP2000305342A - Electrostatic charger and image forming device - Google Patents

Electrostatic charger and image forming device

Info

Publication number
JP2000305342A
JP2000305342A JP11466799A JP11466799A JP2000305342A JP 2000305342 A JP2000305342 A JP 2000305342A JP 11466799 A JP11466799 A JP 11466799A JP 11466799 A JP11466799 A JP 11466799A JP 2000305342 A JP2000305342 A JP 2000305342A
Authority
JP
Japan
Prior art keywords
voltage
charging
charged
surface potential
image
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.)
Pending
Application number
JP11466799A
Other languages
Japanese (ja)
Inventor
Atsuya Oojiya
篤哉 大慈彌
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Ricoh Co Ltd
Original Assignee
Ricoh Co Ltd
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 Ricoh Co Ltd filed Critical Ricoh Co Ltd
Priority to JP11466799A priority Critical patent/JP2000305342A/en
Publication of JP2000305342A publication Critical patent/JP2000305342A/en
Pending legal-status Critical Current

Links

Abstract

PROBLEM TO BE SOLVED: To decide an appropriate voltage to be applied to an electrostatic charging roller, in accordance with the change of an electrostatic capacity due to the shaving of a photoreceptor and the environment, etc., and in accordance with the ambient temperature, and to prevent the occurrence of surface staining and the reduction of image density. SOLUTION: Two kinds of voltage, V1 and V2 equal to or exceeding a discharge start voltage Vth are applied to the electrostatic charging roller, and then, flowing currents I1 and I2 are measured, and the discharge start voltage Vth is obtained from a voltage V when I=0 is established in an expression; I-I1=((I2-I1)/(V2-V1)}(V-V1). Besides, a temperature detecting means is arranged near the electrostatic charger, and the voltage Vc to be applied on the electrostatic charging roller is obtained in accordance with the detected temperature in order to obtain a desired photoreceptor surface potential Vd by using the inclination α of the photoreceptor surface potential Vd with respect to the applied voltage experimentally obtained beforehand, that is, by using Vc=Vth+Vd/α, and then, the Vc is applied on the electrostatic charging roller so as to obtain a fixed photoreceptor surface potential Vd.

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】本発明は帯電装置及び画像形
成装置に関し、より詳しくは、被帯電体に対して帯電部
材を接触させあるいは微小な隙間を介して対向させて配
設し、帯電部材に直流電圧を印加して被帯電体に対して
放電を行わせて被帯電体の帯電(本明細書において帯電
というときは除電をも含む。)を行う帯電装置及びこの
ような帯電装置を像担持体の帯電手段とする画像形成装
置に関する。
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a charging device and an image forming apparatus, and more particularly, to a charging member in which a charging member is brought into contact with or opposed to a member to be charged via a minute gap. A charging device for applying a DC voltage to discharge an object to be charged to charge the object to be charged (charging in this specification includes charge elimination), and an image bearing device for such a charging device The present invention relates to an image forming apparatus serving as a body charging unit.

【0002】[0002]

【従来の技術】従来、例えば電子写真複写機やプリンタ
等の画像形成装置においては、感光体や静電記録誘電体
等の像担持体の帯電手段としてコロナ放電器が広く利用
されていた。しかしコロナ放電器を用いた帯電処理系
は、高電圧印加が必要で帯電効率が低く、加えてコロナ
放電生成物(О3、NОX等)の発生や放電ワイヤの汚
れ等の問題があった。
2. Description of the Related Art Conventionally, in an image forming apparatus such as an electrophotographic copying machine or a printer, a corona discharger has been widely used as a charging means for an image carrier such as a photoconductor or an electrostatic recording dielectric. However charging processing system using a corona discharger, a high voltage application needs charging efficiency is low, in addition the corona discharge products (О 3, NОX etc.) has a problem such as dirt generation and discharge wires.

【0003】そこで近年では、オゾンレス、低電力等の
特長を有する接触帯電装置が注目され、実用化されてき
ている。この接触帯電装置は、感光体等の被帯電体に対
して導電性の帯電部材を接触させ、帯電部材に電圧を印
加して被帯電体に対して放電を行わせ、それによって被
帯電体の表面を所定の電位に帯電させるものである。な
お、帯電部材を被帯電体に対して接触させずに被帯電体
面との間に放電現象を生じ得る微小な空気間隙(エアギ
ャップ)を介して非接触に対向配設させて帯電部材に所
要の帯電バイアスを印加しても、帯電部材を被帯電体に
当接させて配置した場合と同様に被帯電体面の帯電処理
を実行させることができる。
[0003] In recent years, a contact charging device having features such as ozonelessness and low power consumption has attracted attention and has been put to practical use. In this contact charging device, a conductive charging member is brought into contact with a member to be charged such as a photoreceptor, and a voltage is applied to the charging member to cause the member to be discharged to discharge. The surface is charged to a predetermined potential. The charging member is disposed in a non-contact and opposed manner through a minute air gap (air gap) that may cause a discharge phenomenon between the charging member and the surface of the member without contact with the member. Even when the charging bias is applied, the charging process on the surface of the charged body can be executed in the same manner as in the case where the charging member is arranged in contact with the charged body.

【0004】ところが接触帯電装置では、被帯電体に経
年的に生じる削れや、環境等に起因する被帯電体や帯電
部材の静電容量の変化等で放電開始電圧が変化し、この
放電開始電圧の変化によって被帯電体の帯電電位が変化
することがある。画像形成装置の場合は、被帯電体とし
ての感光体の削れ等による静電容量の変化に起因する放
電開始電圧の変化で帯電電位が初期に設定した所望の値
からずれてしまい、これによって画像が乱れる不具合が
生じることがある。
However, in the contact charging device, the discharge starting voltage changes due to abrasion of the member to be charged over time, and changes in the capacitance of the member to be charged and the charging member due to the environment and the like. May change the charging potential of the member to be charged. In the case of an image forming apparatus, the charging potential deviates from a desired value initially set due to a change in a discharge starting voltage due to a change in capacitance due to abrasion of a photoreceptor as a member to be charged. May be disturbed.

【0005】そこで、特開平06−194933号公報
に開示の帯電装置及び画像形成装置においては、放電開
始電圧以降は、印加電圧に対して傾き1で線形に感光体
表面電位が増加するとし、電子写真に必要とされる所要
の感光体表面電位を得るためには帯電ローラには感光体
表面電位+放電開始電圧の電圧を印加すれば良いとし
て、帯電部材に微小電流の定電流を流し、これによって
掛かる電圧を測定することにより放電開始電圧を決定
し、これに基づいて帯電部材に印加する電圧を決定して
いる。
In the charging device and the image forming apparatus disclosed in Japanese Patent Application Laid-Open No. 06-194933, the surface potential of the photosensitive member increases linearly with a slope of 1 with respect to the applied voltage after the discharge starting voltage. To obtain the required photoreceptor surface potential required for photography, it is sufficient to apply a voltage of photoreceptor surface potential + discharge start voltage to the charging roller. The discharge start voltage is determined by measuring the applied voltage, and the voltage to be applied to the charging member is determined based on the voltage.

【0006】[0006]

【発明が解決しようとする課題】しかしながら、実際の
画像形成装置では、帯電部材の材質や画像形成装置の線
速により印加電圧に対する感光体表面電位が傾き1の線
形にならない場合があるので、所要の感光体表面電位に
するための帯電ローラ印加電圧は「感光体表面電位+放
電開始電圧」にはならない。そのため、特開平06−1
94933号公報に開示のようにして帯電ローラ印加電
圧を決定すると、地汚れや濃度低下等の画像品質不良が
発生する。
However, in an actual image forming apparatus, the photosensitive member surface potential with respect to the applied voltage may not be linear with a slope 1 depending on the material of the charging member and the linear speed of the image forming apparatus. The voltage applied to the charging roller to make the surface potential of the photoreceptor not equal to “photoreceptor surface potential + discharge starting voltage”. Therefore, Japanese Patent Application Laid-Open No. H06-1
When the voltage applied to the charging roller is determined as disclosed in Japanese Unexamined Patent Publication No. 94933, image quality defects such as background contamination and reduced density occur.

【0007】さらに、帯電ローラの温度により印加電圧
に対する感光体表面電位が傾き1の線形にならない場合
があり、この場合も所要の感光体表面電位とするための
帯電ローラ印加電圧は、やはり「感光体表面電位+放電
開始電圧」にはならず、上記と同様の問題が発生する。
In some cases, the surface potential of the photosensitive member with respect to the applied voltage does not become linear with a slope of 1 depending on the temperature of the charging roller. It does not become “body surface potential + discharge starting voltage”, and the same problem as described above occurs.

【0008】そこで本発明は、被帯電体や像担持体の経
年的な削れや、環境等による被帯電体や像担持体、帯電
部材の静電容量の変化に加えて、画像形成装置の帯電装
置近傍の温度に応じて適切な帯電ローラへの印加電圧を
決定することができるようにすることにより、地肌汚れ
や画像濃度低下の発生を防止できる帯電装置を提供する
ことを目的とする。
Accordingly, the present invention provides a method for charging an image forming apparatus in addition to abrasion of a member to be charged and an image carrier over time and a change in capacitance of the member to be charged, an image carrier and a charging member due to an environment or the like. It is an object of the present invention to provide a charging device capable of preventing the occurrence of background contamination and a decrease in image density by being able to determine an appropriate voltage to be applied to a charging roller in accordance with the temperature in the vicinity of the device.

【0009】[0009]

【課題を解決するための手段】本発明の請求項1に係る
帯電装置は、上記目的を達成するために、被帯電体に対
して帯電部材を接触させあるいは被帯電体と帯電部材を
微小な隙間を介して対向配設し、上記帯電部材に直流電
圧を印加して上記被帯電体に対して放電を行わせて上記
被帯電体を帯電する帯電装置において、上記帯電部材に
微小電流値の定電流を流し、該定電流によって掛かる電
圧を測定することにより上記放電の開始電圧を求める制
御手段を有するとともに、近傍に温度検知手段を設け、
上記制御手段が、あらかじめ求めた温度差による印加電
圧に対する上記被帯電体の表面電位の傾きの違いの関係
を用い、検知温度に応じて上記帯電部材に適した印加電
圧を算出することを特徴とする。
According to a first aspect of the present invention, there is provided a charging device in which a charging member is brought into contact with a member to be charged or a charging member is minutely contacted with the member to be charged. In the charging device, which is disposed opposite to each other with a gap therebetween and applies a DC voltage to the charging member to discharge the member to be charged and charge the member to be charged, the charging member has a small current value. A constant current is supplied, and control means for obtaining the discharge start voltage by measuring a voltage applied by the constant current is provided, and a temperature detection means is provided in the vicinity,
The control means calculates an applied voltage suitable for the charging member according to a detected temperature using a relationship between a difference in surface potential of the object to be charged and an applied voltage based on a temperature difference obtained in advance. I do.

【0010】また本発明の請求項2に係る画像形成装置
は、上記目的を達成するために、像担持体を帯電する工
程を含む作像プロセスを適用して画像形成を実行する画
像形成装置であって、上記像担持体に対して帯電部材を
接触させあるいは上記像担持体と帯電部材を微小な隙間
を介して対向配設し、上記帯電部材に直流電圧を印加し
て上記像担持体に対して放電を行わせて上記像担持体を
帯電させる帯電装置と、上記帯電部材に微小電流値の定
電流を流し、該定電流によって掛かる電圧を測定するこ
とにより上記放電の開始電圧を求める制御手段を有する
とともに、上記帯電装置の近傍に温度検知手段を設け、
上記制御手段が、あらかじめ求めた温度差による印加電
圧に対する上記像担持体の表面電位の傾きの違いの関係
を用い、検知温度に応じて上記帯電部材に適した印加電
圧を算出することを特徴とする。
According to a second aspect of the present invention, there is provided an image forming apparatus for performing image formation by applying an image forming process including a step of charging an image carrier to achieve the above object. Then, a charging member is brought into contact with the image carrier or the image carrier and the charging member are disposed to face each other with a small gap therebetween, and a DC voltage is applied to the charging member to apply a DC voltage to the image carrier. A charging device that discharges the image bearing member to charge the image bearing member, and a control that applies a constant current of a minute current value to the charging member and measures a voltage applied by the constant current to obtain a discharge starting voltage. Means, and a temperature detecting means is provided near the charging device,
The control means calculates an applied voltage suitable for the charging member according to a detected temperature by using a relationship between a difference in surface potential of the image carrier and an applied voltage based on a temperature difference obtained in advance. I do.

【0011】[0011]

【発明の実施の形態及び実施例】以下本発明の実施の形
態及び実施例を図面を参照して説明する。図1は本発明
の一実施形態となる画像形成装置の概略構成図である。
本例の画像形成装置は転写式電子写真プロセスを利用し
たレーザビームプリンタである。
Embodiments and examples of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic configuration diagram of an image forming apparatus according to an embodiment of the present invention.
The image forming apparatus of this example is a laser beam printer using a transfer type electrophotographic process.

【0012】図中1は像担持体(被帯電体)としての感
光体ドラムであり、この感光体ドラム1は、例えば直径
30mmの円筒状OPC感光体で、電荷発生層の上に厚
さ25μmの電荷輸送層(CT層)を配置し、紙面に垂
直方向の中心軸線を中心に図中矢示のように時計方向X
に所定のプロセススピード(周速度:例えば90mm/
秒)で回転駆動される。
In FIG. 1, reference numeral 1 denotes a photosensitive drum as an image carrier (charged body). The photosensitive drum 1 is, for example, a cylindrical OPC photosensitive member having a diameter of 30 mm, and has a thickness of 25 μm on a charge generating layer. And a charge transport layer (CT layer) is disposed in a clockwise direction X as shown by an arrow in FIG.
A predetermined process speed (peripheral speed: for example, 90 mm /
Seconds).

【0013】また図中2は感光体ドラム1に接触させた
帯電部材としての帯電ローラであり、この帯電ローラ2
は感光体ドラム1の回転に従動して回転し、また電圧部
(HVT、電源部)3から所定の帯電バイアスが印加さ
れ、回転する感光体ドラム1の周面を所定の極性・電位
に一様に帯電(本例では負帯電)させる。
In FIG. 1, reference numeral 2 denotes a charging roller as a charging member brought into contact with the photosensitive drum 1;
Rotates following the rotation of the photosensitive drum 1, and a predetermined charging bias is applied from a voltage unit (HVT, power supply unit) 3 to bring the peripheral surface of the rotating photosensitive drum 1 to a predetermined polarity and potential. (In this example, negative charge).

【0014】このように帯電させた感光体ドラム1の帯
電処理面に、レーザビームスキャナ4から出力する画像
変調されたレーザビームLを照射(走査露光)し、露光
部分の電位を減衰させて静電潜像を形成する。そして感
光体ドラム1の回転にともなって潜像が現像器5に対向
する現像部位に到来すると、現像器5から負帯電された
トナーを供給して反転現像によってトナー像を形成す
る。感光体ドラム1の回転方向で現像器5の下流側には
導電性転写ローラ6を感光体ドラム1に圧接配置してあ
って、感光体ドラム1と導電性転写ローラ6のニップ部
が転写部位を形成している。
An image-modulated laser beam L output from the laser beam scanner 4 is irradiated (scanning exposed) onto the charged surface of the photosensitive drum 1 charged in this way, and the potential of the exposed portion is attenuated and statically applied. An electrostatic latent image is formed. Then, when the latent image arrives at a developing site facing the developing device 5 with the rotation of the photosensitive drum 1, negatively charged toner is supplied from the developing device 5 to form a toner image by reversal development. A conductive transfer roller 6 is disposed in pressure contact with the photosensitive drum 1 on the downstream side of the developing device 5 in the rotation direction of the photosensitive drum 1, and a nip portion between the photosensitive drum 1 and the conductive transfer roller 6 forms a transfer portion. Is formed.

【0015】感光体ドラム1の表面に形成されたトナー
像が感光体ドラム1の回転につれて転写部位に到達する
と、これとタイミングをあわせて、ガイド7から転写材
Pが転写部位に供給され、これとともに電圧部3によっ
て所定の時点で所定の電圧が転写ローラ6に印加され、
トナー像が感光体ドラム1の表面から転写材Pに転移す
る。転写部位でトナー像の転写を受けた転写材Pは、定
着器8へ搬送されてトナー像の定着を受け、機外へ排出
される。図中10はコントロール部(CPU)で、この
コントロール部10により電源部3を制御する。
When the toner image formed on the surface of the photosensitive drum 1 reaches the transfer site as the photosensitive drum 1 rotates, the transfer material P is supplied from the guide 7 to the transfer site at the same time as the toner image. At the same time, a predetermined voltage is applied to the transfer roller 6 at a predetermined time by the voltage unit 3,
The toner image is transferred from the surface of the photosensitive drum 1 to the transfer material P. The transfer material P on which the toner image has been transferred at the transfer portion is conveyed to the fixing device 8, where the toner image is fixed, and discharged out of the apparatus. In the figure, reference numeral 10 denotes a control unit (CPU) which controls the power supply unit 3.

【0016】一方、感光体ドラム1の表面に残った転写
残トナーは、ウレタン製のカウンターブレード(クリー
ニングブレード)9によって掻き落とし、感光体ドラム
1の表面を清掃して次の画像形成に備える。
On the other hand, the transfer residual toner remaining on the surface of the photosensitive drum 1 is scraped off by a urethane counter blade (cleaning blade) 9, and the surface of the photosensitive drum 1 is cleaned to prepare for the next image formation.

【0017】感光体ドラム1は、耐久通紙によってすこ
しずつ削れを生じる。帯電ローラ2は、表面に高抵抗層
を持つ二層構成となっている。これは、感光体ドラム1
にピンホールが生じた場合、その部分に帯電電流が集中
し、帯電ローラ2の表面電位が降下して横筋の帯電不良
になることを防ぐためのものである。また現像器5は2
成分現像方式を用いており、感光体ドラム1の周面の静
電潜像が非磁性トナーによって反転現像を受け、露光さ
れた部分がトナー可視化される。転写ローラ6には例え
ば3kVの電圧を印加して転写を行わせる。
The photosensitive drum 1 is slightly scraped by durable paper passing. The charging roller 2 has a two-layer configuration having a high resistance layer on the surface. This is the photosensitive drum 1
When a pinhole is formed in the charging roller 2, the charging current is concentrated on that portion, and the surface potential of the charging roller 2 is prevented from dropping to prevent poor charging of the horizontal streaks. The developing device 5 is 2
The electrostatic latent image on the peripheral surface of the photosensitive drum 1 is subjected to reversal development with a non-magnetic toner, and the exposed portion is visualized with the toner. For example, a voltage of 3 kV is applied to the transfer roller 6 to perform transfer.

【0018】図2をも参照して帯電ローラ2に印加する
電圧の制御について説明する。既に述べたように、帯電
ローラ2にDC電圧を印加した場合、印加電圧が放電開
始電圧Vth以上で帯電を開始し、それ以降は印加電圧
の増加分と同じ割合で感光体表面電位が上昇する。この
ことから、環境や感光体の削れを無視した場合には、目
標とする感光体表面電位Vdに放電開始電圧Vthを加
えた電圧で帯電ローラ2を制御すれば良いが、図2に示
すように、環境を変化させた場合や感光体ドラム1が削
れた場合には、放電開始電圧Vthが変化するために定
電圧で制御していては感光体表面電位Vdの値が変化し
てしまうことになる。すなわち図2に示すように、N/
N環境の耐久後と、L/L環境の初期とは160Vもの
感光体表面電位Vdの差が生じる。もし、放電開始電圧
Vthを通常環境の初期状態を仮定して640Vと見積
もって定電圧制御を行っていると、L/L環境では感光
体表面電位Vdが下降して地汚れを生じ、また耐久後で
は感光体表面電位Vdが大幅に高くなり、それにより帯
電電位VLが上昇して画像濃度が低くなる。放電開始電
圧Vthの変化を検知するためには、プリンタ本体に感
光体表面電位測定器を設ければ良いが、コストが上昇す
るし、別途の電源等のハードウェアが必要になる。
The control of the voltage applied to the charging roller 2 will be described with reference to FIG. As described above, when a DC voltage is applied to the charging roller 2, charging starts when the applied voltage is equal to or higher than the discharge start voltage Vth, and thereafter, the surface potential of the photoconductor increases at the same rate as the increase in the applied voltage. . For this reason, when the environment and the scraping of the photoconductor are ignored, the charging roller 2 may be controlled by a voltage obtained by adding the discharge start voltage Vth to the target photoconductor surface potential Vd, as shown in FIG. In addition, when the environment is changed or the photosensitive drum 1 is scraped, the value of the photosensitive member surface potential Vd may change if the discharge start voltage Vth is changed and the control is performed with a constant voltage. become. That is, as shown in FIG.
After the endurance of the N environment and the initial stage of the L / L environment, there is a difference of 160 V between the photoconductor surface potentials Vd. If the constant voltage control is performed by estimating the discharge start voltage Vth to be 640 V assuming the initial state of the normal environment, in the L / L environment, the photoconductor surface potential Vd decreases to cause background contamination, and endurance occurs. Later, the photoconductor surface potential Vd is significantly increased, thereby increasing the charged potential VL and lowering the image density. In order to detect a change in the discharge start voltage Vth, a photoconductor surface potential measuring device may be provided in the printer body, but this increases the cost and requires additional hardware such as a power supply.

【0019】本実施形態では、帯電ローラ2に印加する
電圧とこれによって流れる帯電電流を検知し、この関係
から放電開始電圧Vthを予測して制御する。具体的に
は、図3に示すように放電開始電圧Vth以上の2つの
電圧V1、V2を帯電ローラ2に印加し、それぞれ流れ
る電流I1、I2を測定する。この時、感光体ドラム1
の電位はある決まった値でないと帯電電位と帯電電流の
関係が明らかにならないため、画像露光を行い、電位を
0にした状態で測定を行う。図3で、放電開始電圧Vt
hとは放電開始を表すA点であるため、電圧V1、V2
印加時に流れる電流I1、I2を測定し、これによって
求められる一次方程式
In the present embodiment, the voltage applied to the charging roller 2 and the charging current flowing thereby are detected, and the discharge start voltage Vth is predicted and controlled based on this relationship. Specifically, as shown in FIG. 3, two voltages V1 and V2 equal to or higher than the discharge start voltage Vth are applied to the charging roller 2, and currents I1 and I2 flowing therethrough are measured. At this time, the photosensitive drum 1
Since the relationship between the charging potential and the charging current cannot be clarified unless the potential is a fixed value, image exposure is performed and measurement is performed with the potential set to zero. In FIG. 3, the discharge starting voltage Vt
Since h is the point A indicating the start of discharge, the voltages V1 and V2
The currents I1 and I2 flowing at the time of application are measured, and a linear equation obtained by the measurement is obtained.

【数1】I−I1={(I2−I1)/(V2−V
1)}(V−V1) のI=0の時の電圧Vを計算することによって放電開始
電圧Vthを求める。
I-I1 = {(I2-I1) / (V2-V
1) The discharge start voltage Vth is obtained by calculating the voltage V when I = 0 of} (V−V1).

【0020】そして、印加電圧に対する感光体表面電位
Vdの傾きが1の線形の場合には、上記数式1にて求め
た放電開始電圧Vthに所望の感光体表面電位Vdを加
算した電圧Vc(Vc=Vth+Vd)を帯電ローラ2
に印加することによって、感光体1の削れ、環境の変動
にかかわらず一定の感光体表面電位Vdを得る。
When the slope of the photosensitive member surface potential Vd with respect to the applied voltage is linear, the voltage Vc (Vc) is obtained by adding the desired photosensitive member surface potential Vd to the discharge starting voltage Vth obtained by the above equation (1). = Vth + Vd) to the charging roller 2
, A constant photoconductor surface potential Vd is obtained irrespective of scraping of the photoconductor 1 and fluctuations in the environment.

【0021】これも既に述べたが、図4、5に示すよう
に、実際の画像形成装置では帯電装置の温度により印加
電圧に対する感光体表面電位が傾き1の線形にならない
場合がある。従って、気温が高い場所や低い場所で画像
形成装置を使用する場合や冬期の朝昼で温度差が大きい
場合は従来の技術で述べた問題が生じ得る。そこで、帯
電装置近傍に温度検知手段11(例えば、サーミスタ)
を設け、その検知温度に応じてあらかじめ実験的に求め
た印加電圧に対する感光体表面電位Vdの傾きαを
As described above, as shown in FIGS. 4 and 5, in an actual image forming apparatus, the surface potential of the photosensitive member with respect to the applied voltage may not be linear with a slope 1 depending on the temperature of the charging device. Therefore, when the image forming apparatus is used in a place where the temperature is high or low, or when the temperature difference is large between morning and noon in winter, the problem described in the related art may occur. Therefore, the temperature detecting means 11 (for example, a thermistor) is provided near the charging device.
And the slope α of the photoconductor surface potential Vd with respect to the applied voltage experimentally obtained in advance in accordance with the detected temperature.

【数2】α=ΔVd/ΔVc として求め、これを用いて所要の感光体表面電位Vdに
するための帯電ローラ印加電圧Vcを求める。具体的に
は印加電圧Vcは
## EQU2 ## The value is determined as α = ΔVd / ΔVc, and using this, the voltage Vc applied to the charging roller for obtaining the required photoconductor surface potential Vd is determined. Specifically, the applied voltage Vc is

【数3】Vc=Vth+Vd/α となる。なお、帯電装置近傍の温度と相関があれば適宜
の場所の温度を検知して利用できる。
Vc = Vth + Vd / α If there is a correlation with the temperature near the charging device, the temperature at an appropriate place can be detected and used.

【0022】実際に画像形成を行った例を示して説明す
る。帯電装置近傍温度が15℃(この時、α=0.
9)、L/L環境でCT層が15μmまで削れた感光体
ドラムを用いて上記の制御を行った。前回転時にV1=
1200V、V2=1800Vをそれぞれ印加した時に
流れる電流はそれぞれ30μA、60μAであった。こ
の測定時は常に画像露光を行い、帯電前の感光体電位を
0Vとしておいた。
An example in which an image is actually formed will be described. When the temperature in the vicinity of the charging device is 15 ° C.
9) In the L / L environment, the above-mentioned control was performed using the photoconductive drum from which the CT layer was cut to 15 μm. V1 =
The currents flowing when 1200 V and V2 = 1800 V were applied were 30 μA and 60 μA, respectively. During this measurement, image exposure was always performed, and the potential of the photoconductor before charging was set to 0V.

【0023】電圧V1、V2印加時に流れる電流I1、
I2の値を前述の数式1に代入すると、放電開始電圧V
th=600Vと求まるため、この値に、必要な感光体
表面電位Vd=900Vに1/αを乗じた値、すなわち
900/1.1=818Vを加えた電圧1418Vを画
像形成時の印加電圧Vcに決定し、この電圧で画像形成
を行ったところ、良好な画像を得ることができ、この時
の感光体表面電位Vdを測定したところ890Vで、予
測した値と近い値を得た。
The current I1, which flows when the voltages V1, V2 are applied,
When the value of I2 is substituted into the above-described equation 1, the discharge starting voltage V
Since th = 600 V is obtained, a value obtained by multiplying this value by 1 / α to a necessary photoconductor surface potential Vd = 900 V, that is, 900 / 1.1 = 818 V is added, and a voltage of 1418 V is applied to the image forming voltage Vc. When the image was formed at this voltage, a good image could be obtained. When the surface potential Vd of the photoconductor at this time was measured, it was 890 V, and a value close to the predicted value was obtained.

【0024】一方、本発明を用いないで印加電圧に対す
る感光体表面電位Vdの傾きαを1とした場合は、放電
開始電圧Vth=600Vに900Vを加えた電圧15
00Vを帯電ローラ2に印加することになり、この時の
感光体表面電位Vdは980Vになってしまったため、
画像部の電位が上昇し、画像濃度が低く(明るく)なっ
てしまった。すなわち、単純に印加電圧に対する感光体
表面電位Vdの傾きα=1とすると帯電装置近傍の温度
によっては画像が劣化することがあるが、本発明では上
述のようにこれを抑えることができた。
On the other hand, when the inclination α of the photosensitive member surface potential Vd with respect to the applied voltage is set to 1 without using the present invention, the voltage 15 obtained by adding 900 V to the discharge starting voltage Vth = 600 V is used.
00V is applied to the charging roller 2, and the photoconductor surface potential Vd at this time has become 980V.
The potential of the image portion increased, and the image density became low (bright). That is, if the inclination α of the photosensitive member surface potential Vd with respect to the applied voltage is simply set to 1, the image may be deteriorated depending on the temperature in the vicinity of the charging device. However, in the present invention, this can be suppressed as described above.

【0025】[0025]

【発明の効果】請求項1に係る帯電装置は、以上説明し
てきたようなものなので、被帯電体の削れや、環境等に
起因する被帯電体や帯電部材の静電容量の変化に加え
て、装置近傍の温度に応じて適切な帯電ローラ印加電圧
を決定でき、画像形成装置の使用環境温度にかかわら
ず、被帯電体の帯電電位を安定化することができるとい
う効果がある。
The charging device according to the first aspect is as described above. Therefore, in addition to the scraping of the charged body and the change in the capacitance of the charged body and the charging member due to the environment, etc. In addition, an appropriate voltage applied to the charging roller can be determined according to the temperature in the vicinity of the apparatus, and the charging potential of the member to be charged can be stabilized irrespective of the ambient temperature of the image forming apparatus.

【0026】請求項2に係る画像形成装置は、以上説明
してきたようなものなので、使用環境温度にかかわら
ず、被帯電体である感光体等の像担持体の帯電電位を安
定化することができ、常に良好な画像を安定して出力す
ることができるという効果がある。
Since the image forming apparatus according to the second aspect is as described above, it is possible to stabilize the charging potential of an image carrier such as a photosensitive member, which is a member to be charged, regardless of the ambient temperature. Thus, there is an effect that a good image can always be output stably.

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

【図1】本発明の一実施形態となる画像形成装置の概略
構成図である。
FIG. 1 is a schematic configuration diagram of an image forming apparatus according to an embodiment of the present invention.

【図2】帯電ローラに印加する電圧の制御例を示す図で
ある。
FIG. 2 is a diagram illustrating a control example of a voltage applied to a charging roller.

【図3】帯電ローラに印加した放電開始電圧以上の電圧
とこれによって流れる電流の関係を示す図である。
FIG. 3 is a diagram showing the relationship between a voltage equal to or higher than a discharge starting voltage applied to a charging roller and a current flowing thereby.

【図4】印加電圧に対する感光体表面電位の傾きの関係
を示す図である。
FIG. 4 is a diagram illustrating a relationship between a slope of a photoconductor surface potential and an applied voltage.

【図5】印加電圧に対する感光体表面電位の傾きが温度
によって変化する例を示す図である。
FIG. 5 is a diagram illustrating an example in which the slope of the photoconductor surface potential with respect to an applied voltage changes with temperature.

【符号の説明】[Explanation of symbols]

1 感光体ドラム 2 帯電ローラ 3 電圧部 4 レーザビームスキャナ 5 現像器 6 導電性転写ローラ 7 ガイド 8 定着器 9 カウンターブレード(クリーニングブレード) 10 コントロール部(CPU) 11 温度検知手段 L レーザビーム P 転写材 Vth 放電開始電圧 Vd 感光体表面電位 REFERENCE SIGNS LIST 1 photoconductor drum 2 charging roller 3 voltage section 4 laser beam scanner 5 developing device 6 conductive transfer roller 7 guide 8 fixing device 9 counter blade (cleaning blade) 10 control section (CPU) 11 temperature detecting means L laser beam P transfer material Vth Discharge start voltage Vd Photoconductor surface potential

Claims (2)

【特許請求の範囲】[Claims] 【請求項1】 被帯電体に対して帯電部材を接触させあ
るいは被帯電体と帯電部材を微小な隙間を介して対向配
設し、上記帯電部材に直流電圧を印加して上記被帯電体
に対して放電を行わせて上記被帯電体を帯電する帯電装
置において、上記帯電部材に微小電流値の定電流を流
し、該定電流によって掛かる電圧を測定することにより
上記放電の開始電圧を求める制御手段を有するととも
に、近傍に温度検知手段を設け、上記制御手段が、あら
かじめ求めた温度差による印加電圧に対する上記被帯電
体の表面電位の傾きの違いの関係を用い、検知温度に応
じて上記帯電部材に適した印加電圧を算出することを特
徴とする帯電装置。
1. A charging member is brought into contact with a member to be charged or a charging member and a member to be charged are disposed to face each other with a small gap therebetween. A DC voltage is applied to the charging member to apply a charge to the member to be charged. In the charging device for discharging the object to be charged by charging the object to be charged, a constant current having a minute current value is applied to the charging member, and a voltage applied by the constant current is measured to obtain a discharge starting voltage. Means, and a temperature detecting means is provided in the vicinity, and the control means uses the relationship between the gradient of the surface potential of the object to be charged and the applied voltage due to a previously determined temperature difference, and performs the charging in accordance with the detected temperature. A charging device for calculating an applied voltage suitable for a member.
【請求項2】 像担持体を帯電する工程を含む作像プロ
セスを適用して画像形成を実行する画像形成装置であっ
て、上記像担持体に対して帯電部材を接触させあるいは
上記像担持体と帯電部材を微小な隙間を介して対向配設
し、上記帯電部材に直流電圧を印加して上記像担持体に
対して放電を行わせて上記像担持体を帯電させる帯電装
置と、上記帯電部材に微小電流値の定電流を流し、該定
電流によって掛かる電圧を測定することにより上記放電
の開始電圧を求める制御手段を有するとともに、上記帯
電装置の近傍に温度検知手段を設け、上記制御手段が、
あらかじめ求めた温度差による印加電圧に対する上記像
担持体の表面電位の傾きの違いの関係を用い、検知温度
に応じて上記帯電部材に適した印加電圧を算出すること
を特徴とする画像形成装置。
2. An image forming apparatus for performing image formation by applying an image forming process including a step of charging an image carrier, wherein a charging member is brought into contact with said image carrier or said image carrier is contacted. A charging device that charges the image carrier by applying a DC voltage to the charging member to cause the image carrier to discharge by applying a DC voltage to the charging member; A constant current having a minute current value is passed through the member, and a control means for obtaining the discharge starting voltage by measuring a voltage applied by the constant current is provided. A temperature detecting means is provided near the charging device, and the control means is provided. But,
An image forming apparatus comprising: calculating an applied voltage suitable for the charging member according to a detected temperature by using a relationship between a difference in surface potential of the image carrier and an applied voltage based on a temperature difference obtained in advance.
JP11466799A 1999-04-22 1999-04-22 Electrostatic charger and image forming device Pending JP2000305342A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP11466799A JP2000305342A (en) 1999-04-22 1999-04-22 Electrostatic charger and image forming device

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP11466799A JP2000305342A (en) 1999-04-22 1999-04-22 Electrostatic charger and image forming device

Publications (1)

Publication Number Publication Date
JP2000305342A true JP2000305342A (en) 2000-11-02

Family

ID=14643588

Family Applications (1)

Application Number Title Priority Date Filing Date
JP11466799A Pending JP2000305342A (en) 1999-04-22 1999-04-22 Electrostatic charger and image forming device

Country Status (1)

Country Link
JP (1) JP2000305342A (en)

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2003302808A (en) * 2002-04-12 2003-10-24 Canon Inc Image forming apparatus, process cartridge and electrifying roller
US6640063B2 (en) * 2000-12-19 2003-10-28 Canon Kabushiki Kaisha Image forming apparatus featuring first and second peak-to-peak charging voltages, respectively, corresponding to first and second image bearing member speeds and voltage frequencies
US6999690B2 (en) * 2002-07-18 2006-02-14 Canon Kabushiki Kaisha Image forming apparatus
JP2006154006A (en) * 2004-11-25 2006-06-15 Fuji Xerox Co Ltd Image forming apparatus and method of setting transfer current value
JP2008170948A (en) * 2006-12-13 2008-07-24 Canon Inc Image forming apparatus
US8548348B2 (en) 2010-03-05 2013-10-01 Canon Kabushiki Kaisha High-voltage output apparatus and image forming apparatus
JP2018124509A (en) * 2017-02-03 2018-08-09 株式会社リコー Image formation apparatus and control method therefor
US10845725B2 (en) 2018-07-20 2020-11-24 Canon Kabushiki Kaisha Image forming apparatus

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6640063B2 (en) * 2000-12-19 2003-10-28 Canon Kabushiki Kaisha Image forming apparatus featuring first and second peak-to-peak charging voltages, respectively, corresponding to first and second image bearing member speeds and voltage frequencies
JP2003302808A (en) * 2002-04-12 2003-10-24 Canon Inc Image forming apparatus, process cartridge and electrifying roller
US6999690B2 (en) * 2002-07-18 2006-02-14 Canon Kabushiki Kaisha Image forming apparatus
JP2006154006A (en) * 2004-11-25 2006-06-15 Fuji Xerox Co Ltd Image forming apparatus and method of setting transfer current value
JP4517828B2 (en) * 2004-11-25 2010-08-04 富士ゼロックス株式会社 Image forming apparatus
JP2008170948A (en) * 2006-12-13 2008-07-24 Canon Inc Image forming apparatus
US8548348B2 (en) 2010-03-05 2013-10-01 Canon Kabushiki Kaisha High-voltage output apparatus and image forming apparatus
US8718505B2 (en) 2010-03-05 2014-05-06 Canon Kabushiki Kaisha High-voltage output apparatus and image forming apparatus
JP2018124509A (en) * 2017-02-03 2018-08-09 株式会社リコー Image formation apparatus and control method therefor
US10845725B2 (en) 2018-07-20 2020-11-24 Canon Kabushiki Kaisha Image forming apparatus

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