JPS6120072A - Electrophotographic device - Google Patents

Abstract

PURPOSE:To improve the transfer efficiency by a simple means which is stable even in long-period use by providing a means which applies a charge having the same polarity with a charge given to a developer between the developing part and transfer part of the electrophotographic device. CONSTITUTION:An electrostatic charging part 3, exposing part 4, developing part 5, and transfer part 8 which transfers a visual image formed by development to a transfer member 7 moving as shown by an arrow 6 are arranged in opposition to a cylindrical photosensitive body 1 in its rotating direction shown by an arrow 2. A device 9 which applies a charge having the same polarity with the developer is provided between the developing part 5 and transfer part 8. For example, the electrostatic charging part 3 gives a plus charge to the surface of the photosensitive body 1 and gives a minus charge to a developer (toner). In this case, when a minus charge is applied by the device 9, a plus charge remaining on the surface of the photosensitive body is neutralized even after an exposing process and the amount of minus charges that the developer has is increased. Consequently, the amount of the developer transferred to the transfer member 7 given a plus charge at the transfer part 8 is increased, thereby improving the transfer efficiency.

Description

【発明の詳細な説明】[Detailed description of the invention] 【発明の属する技術分野】[Technical field to which the invention pertains]

本発明は、移動する感光体上に帯電および像露光等の手
段により形成された静電潜像を、帯電により感光体表面
に与えられた電荷と逆の極性の電荷を与えられた現像剤
（トナー）により顕像化後、生じた可視像を用紙などの
転写部材上に転写する操作を行う電子写真装置に関する
。In the present invention, an electrostatic latent image formed on a moving photoreceptor by means such as charging and image exposure is transferred to a developer (which is charged with a polarity opposite to that applied to the surface of the photoreceptor by charging). The present invention relates to an electrophotographic apparatus that performs an operation of converting a visible image (toner) onto a transfer member such as a sheet of paper.

【従来技術とその問題点】[Prior art and its problems]

上記のような電子写真装置において転写を行う際には、
転写部材に感光体に面する側と反対の側からコロトロン
と称する装置により現像剤の極性と逆の極性を有する電
荷を与え、現像剤との電気的引力を利用して感光体上の
可視像を転写部材上に移動させる方式が一般にとられて
いる。この場合転写効率、すなわち（転写された現像剤
量／顕像化の際与えられた現像剤量）の値をできるだけ
大きくするために、転写前に感光体に露光して現像剤の
もつ電荷を弱めてその剥離を促進する方法が知られてい
る。しかしながら、感光体に用いられる感光材料、すな
わち非晶質セレンあるいはセレン合金、硫化カドミウム
またはＰＶＫ等の有機材料は、いずれも光疲労として知
られた性質を存しており、露光光量の調整、露光光質の
選定に配慮を必要とし、装置として複雑化するという欠
点を有するとともに、長期間にわたる使用においては、
現像剤の飛散による光源の汚れのために初期の目的を果
たすことが不可能になる。When performing transfer using an electrophotographic device such as the one mentioned above,
An electric charge having a polarity opposite to that of the developer is applied to the transfer member from the side opposite to the side facing the photoreceptor using a device called a corotron, and the visible light on the photoreceptor is applied using electrical attraction with the developer. A method is generally used in which the image is moved onto a transfer member. In this case, in order to maximize the transfer efficiency, that is, (amount of transferred developer/amount of developer applied during visualization), the photoreceptor is exposed to light before transfer to reduce the charge held by the developer. Methods of weakening and promoting its peeling are known. However, the photosensitive materials used in photoreceptors, namely organic materials such as amorphous selenium or selenium alloys, cadmium sulfide, or PVK, all have a property known as photofatigue. It has the disadvantage of requiring consideration in the selection of light quality and complicating the device, and when used for a long period of time,
The initial purpose cannot be achieved due to contamination of the light source due to developer scattering.

【発明の目的】[Purpose of the invention]

本発明は、上述の欠点を除去し感光体の感光特性に悪影
響を及ぼすことなく、長期間の使用にあたっても安定し
た簡便な手段により転写効率を向上せしめた電子写真装
置を提供することを目的とする。SUMMARY OF THE INVENTION An object of the present invention is to provide an electrophotographic apparatus that eliminates the above-mentioned drawbacks and improves transfer efficiency by a simple means that is stable even during long-term use without adversely affecting the photosensitive characteristics of the photoreceptor. do.

【発明の要点】[Key points of the invention]

本発明は、電子写真装置の現像部と転写部の間に現像剤
に与えられた電荷と同極性の電荷を感光体上に印加する
手段を備えることにより、現像剤の電荷量を増加せしめ
るとともに、帯電部により感光体表面に与えられた電荷
を中和せしめ、現像剤の転写効率を飛躍的に向上せしめ
るようにしたものである。The present invention increases the amount of charge on the developer by providing means for applying an electric charge of the same polarity as the electric charge applied to the developer onto the photoreceptor between the developing section and the transfer section of an electrophotographic device. , the charge applied to the surface of the photoreceptor by the charging section is neutralized, and the transfer efficiency of the developer is dramatically improved.

【発明の実施例】[Embodiments of the invention]

第１図は本発明の実施例を示すもので、円筒状感光体１
の矢印２で示す回転方向に帯電部３、露光部４、現像部
５および現像によって生じた可視像を矢印６の方向に移
動する転写部材７に転写する転写部８が感光体１に対向
して配置されている。 現像部５と転写部８の間に本発明による現像剤と同極性
を有するｉｔ蒲を印加する装置９が設けられる。この装
置９は、帯電部３あるいは転写部８に用いられると同様
なコロトロン等が適切である。 例えば帯電部３で感光体１の表面に正の電荷を与え、現
像剤（トナー）にそれと逆の負の電荷を与える場合、装
置９により負の電荷を印加すれば、感光体表面に露光後
も残留する正の電荷を中和し、また現像剤の有する負の
電荷量を増加させる。従って、転写部８において正の電
荷を与えられる転写部材７に移る現像剤の量が増加し、
転写効率が増大する。なお、電子写真装置に具備される
分離。 除電、クリーニング等の手段は第１図では省略されてい
る。 第２図は本発明の実施例の装置と従来の装置の転写効率
を比較して示したものであり、実線２１は実施例、点線
２２は比較例を示す、一般に中間ＩＩＩ域においては、
現像されるトナーの粒径分布が径の小さな方向にずれる
傾向があり、その転写効率カ低下する。線２１．２２の
いずれにもその傾向が認められるが、本発明による装置
ではその低下は極めてわずかなものであり、原稿の再現
性の観点からも好ましいものとなっている。 第３図は長期間にわたり使用した場合の転写効率の推移
を示したものであり、実線３１が本発明の実施例の装置
、点線３２は前述のトナー剥離促進用光源を付加した装
置の場合である。本発明による装置においては連続５万
枚コピーにおいても転写効率の低下がほとんど認められ
ないにもかかわらず、比較例の装置では、１万枚程度で
転写効率の低下が認められ、長期間にわたり使用する場
合は図中の矢印で示したように頻繁にクリーニングを行
う必要があり、装置を安定に保持するための費用が必要
となる。FIG. 1 shows an embodiment of the present invention, in which a cylindrical photoreceptor 1
A charging section 3 , an exposing section 4 , a developing section 5 , and a transfer section 8 that transfers a visible image generated by development to a transfer member 7 moving in the direction of an arrow 6 face the photoreceptor 1 in the rotational direction shown by an arrow 2 . It is arranged as follows. A device 9 is provided between the developing section 5 and the transfer section 8 for applying an IT voltage having the same polarity as the developer according to the present invention. As this device 9, a corotron or the like similar to that used in the charging section 3 or the transfer section 8 is suitable. For example, when the charging section 3 applies a positive charge to the surface of the photoreceptor 1 and the opposite negative charge is applied to the developer (toner), if a negative charge is applied by the device 9, the surface of the photoreceptor 1 can be charged after exposure. It also neutralizes the remaining positive charges and increases the amount of negative charges held by the developer. Therefore, the amount of developer transferred to the transfer member 7 that is given a positive charge in the transfer section 8 increases,
Transfer efficiency is increased. In addition, the separation included in the electrophotographic device. Means for static elimination, cleaning, etc. are omitted in FIG. FIG. 2 shows a comparison of the transfer efficiency of the apparatus according to the embodiment of the present invention and the conventional apparatus, where the solid line 21 indicates the embodiment and the dotted line 22 indicates the comparative example. Generally, in the intermediate III range,
The particle size distribution of the toner to be developed tends to shift in the direction of smaller diameters, resulting in lower transfer efficiency. Although this tendency is recognized in both lines 21 and 22, the decrease is extremely slight in the apparatus according to the present invention, which is preferable from the viewpoint of document reproducibility. FIG. 3 shows the transition of transfer efficiency when used over a long period of time, where the solid line 31 indicates the case of the device according to the embodiment of the present invention, and the dotted line 32 indicates the case of the device added with the above-mentioned light source for promoting toner peeling. be. In the device according to the present invention, there is almost no decrease in transfer efficiency even after continuous copying of 50,000 copies, but in the device of the comparative example, a decrease in transfer efficiency is observed after approximately 10,000 copies, and the device is used for a long period of time. In this case, it is necessary to perform frequent cleaning as shown by the arrows in the figure, and costs are required to maintain the device stably.

【発明の効果】【Effect of the invention】

本発明は、感光体表面に可視像を形成する現像剤に与え
られている電荷と同極性の電荷を転写前に付与すること
により、現像剤の電荷量が増加すると共に、それと逆極
性を有する感光体上の残留電荷を中和することにより、
現像剤と感光体との電気的吸着力が必然的に弱められる
と同時に、現像剤と転写部材との電気的引力が強められ
、その転写効率が飛躍的に向上する。また、これらの作
用が電気的に行われることから、感光材料の特性に影響
を与えることがな（、常に一定した像形成を可能とする
ことができる。In the present invention, by applying a charge of the same polarity as the charge given to the developer that forms a visible image on the surface of the photoreceptor before transfer, the amount of charge of the developer is increased, and the polarity opposite to that of the charge is increased. By neutralizing the residual charge on the photoreceptor that has
The electrical adsorption force between the developer and the photoreceptor is inevitably weakened, and at the same time, the electrical attraction between the developer and the transfer member is strengthened, and the transfer efficiency is dramatically improved. Furthermore, since these actions are performed electrically, they do not affect the characteristics of the photosensitive material (and constant image formation is possible at all times).

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

第１図は本発明の一実施例を概念的に示す側面図、第２
図は転写効率と原稿濃度の関係を本発明の実施例と従来
例について示す線図、第３図は長期間複写時の転写効率
の変化を実施例と従来例について示す線図である。FIG. 1 is a side view conceptually showing one embodiment of the present invention, and FIG.
The figure is a diagram showing the relationship between transfer efficiency and document density for the embodiment of the present invention and the conventional example, and FIG. 3 is a diagram showing the change in transfer efficiency during long-term copying for the embodiment and the conventional example.

Claims (1)

【特許請求の範囲】[Claims] １）移動する感光体上に帯電および像露光等の手段によ
り形成された静電潜像を、帯電により感光体表面与えら
れた電荷と逆の極性の電荷を与えられた現像剤により顕
像化後、生じた可視像を転写部材上に転写する操作を行
うものにおいて、現像部と転写部の間に現像剤に与えら
れた電荷と同極性の電荷を感光体上に印加する手段を有
することを特徴とする電子写真装置。1) An electrostatic latent image formed on a moving photoreceptor by means such as charging and image exposure is visualized using a developer charged with a polarity opposite to that given to the surface of the photoreceptor by charging. After that, in a device that performs an operation of transferring the generated visible image onto a transfer member, it has a means for applying an electric charge of the same polarity as the electric charge given to the developer onto the photoreceptor between the developing section and the transfer section. An electrophotographic device characterized by: