JP3579222B2 - Contact charging device - Google Patents

Description

【００３７】
このように導電性支持体を被覆することにより、放電の乱れを防止し帯電が均一になり良好な画像を得られるようになり、かつ帯電中の機密性を保つことで放電状態の乱れを起こさずに良好な画像を得ることが出来る。
【００３８】
【発明の効果】
以上、説明したように請求項１の発明の接触帯電装置によれば、複写機、ファクシミリ、プリンタ等の画像形成装置に使用される被帯電部材と、該被帯電部材を帯電する帯電部材と、前記被帯電部材および帯電部材とともに閉空間の一部を形成する閉空間形成部材と、前記被帯電部材、帯電部材および閉空間形成部材で囲まれる空間を閉空間とする側板とを備え、該閉空間内の放電雰囲気ガスを減圧して帯電部材により被帯電部材を帯電させる接触帯電装置において、前記被帯電部材の表面は少なくとも前記閉空間に露出する部分が誘電物質で被覆されているので、導電体の露出による放電の偏倚を防止することができ、被帯電部材の所望の部分に電荷を載せることができる。
【００３９】
また、請求項２の発明の接触帯電装置によれば、請求項１に記載の接触帯電装置において、前記帯電部材および閉空間形成部材がそれぞれ弾性体からなるので、請求項１の効果に加えて、高機密性を維持することができる。
【００４０】
また、請求項３の発明の接触帯電装置によれば、請求項１〜２の何れかに記載の接触帯電装置において、前記被帯電部材、帯電部材および閉空間形成部材は共に回転体からなり、前記被帯電部材の回転軸、帯電部材の回転軸および閉空間形成部材の回転軸は互いに平行に配置されているので、請求項１〜２の何れかに記載の効果に加えて、回転体に囲まれた閉空間を形成することができる。
【００４１】
また、請求項４の発明の接触帯電装置によれば、請求項１〜３の何れかに記載の接触帯電装置において、前記誘電物質は、有機感光体からなるので、請求項１〜３の何れかに記載の効果に加えて、製造工程を増加することなく作製することができる。
【００４２】
また、請求項５の発明の接触帯電装置によれば、請求項１〜３の何れかに記載の接触帯電装置において、前記誘電物質は、有機感光体部分と有機感光体と異なる誘電体部分とから構成されているので、請求項１〜３の何れかに記載の効果に加えて、有機感光材料の使用を最小にすることができる。
【００４３】
また、請求項６の発明の接触帯電装置によれば、請求項５に記載の接触帯電装置において、前記有機感光体と異なる誘電体部分は無機誘電体部分であるので、請求項５に記載の効果に加えて、有機誘電体を使用することなく、有機感光材料の使用を最小にすることができる。
【図面の簡単な説明】
【図１】本発明の実施の形態に係わる接触帯電装置の正面図である。
【図２】本発明の実施の形態に係わる接触帯電装置のローラの位置関係を示す図である。
【符号の説明】
１ 帯電ローラ
２ ドラム感光体
３ 閉空間形成ローラ
４ 側板[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a contact charging device used for an image forming apparatus such as a copying machine, a facsimile, a printer, and the like.
[0002]
[Prior art]
2. Description of the Related Art In an image forming apparatus such as a copying machine, a printer, and a facsimile, various methods such as a thermal transfer method, a bubble jet method, and an ink jet method are used for visualizing an image. Among these methods, the method most frequently used is a method in which a charge carrier called a toner is charged and transferred and fixed to a transfer target such as paper. That is, as represented by the Carlson process, a charge is charged on a recording medium such as a photoreceptor, and the charge on the charged recording medium is erased with light or the like to form a latent image of a document pattern, and a charge carrier called toner is formed thereon. Is carried out to visualize the image, and then the image is transferred and fixed on paper or the like.
[0003]
In this system, there is a phenomenon of charge transfer in each of the charging, development, transfer, and charge removal processes. In order to cause this phenomenon, it is necessary to cause charge generation and transfer to the photoconductor, charge carrier, or transfer target. That is, an electrical process called charging is performed to transfer the charge carrier.
[0004]
For this purpose, there are methods such as corona charging, contact friction charging, contact charge injection, and ionization by radiation.
[0005]
In the corona charging method, which has been most popular in the past, a high-voltage electric field is applied to a thin wire or a needle electrode to cause a corona discharge between the electrode and a counter electrode. It is a method of putting.
[0006]
In this method, although the principle and the apparatus are very simple, oxygen in the air occupies about 20% by volume. For this reason, in corona discharge in air, when oxygen in air is ionized, ozone O ₃ is generated. This ozone O ₃ is a harmful substance in an office environment even if it is a molecule necessary in the air and is not preferable to be generated.
[0007]
Thus, a method of contacting a charging member with a member to be charged and injecting electric charge, and a method of discharging at a short distance by using Paschen's law to reduce the generation of ozone have begun to be used. Contact friction charging and contact charge injection systems are used as developing rollers and charging rollers.
[0008]
However, when the charging member comes into contact with the member to be charged when the roller is stopped, low-molecular components of the roller are deposited and transferred, so that the member to be charged is contaminated, resulting in a problem such as an abnormal image. Although ionization due to radiation depends on the type of radiation, it requires prevention of exposure to radiation, and has not been put to practical use at present.
[0009]
Therefore, recently, even in the contact charging method, a method has been adopted in which the surface of the charging member is made to have a high resistance and discharged in a minute space before and after contact with the photoreceptor which is the member to be charged and the charge is supplied to the photoreceptor. I have.
[0010]
However, even in the contact charging method, the basic principle is to generate corona ions as with corona discharge, ozone O ₃ and Knox NO _X in the air discharge inevitably occurs.
[0011]
This NO _X component is hygroscopic, and if this component adheres to the photoreceptor, an abnormal image called image deletion occurs. Further, the NO _X component adheres to the photoreceptor and the charging roller, and the low-molecular component from the charging roller is removed when both contact. There is a problem that the toner adheres to the photoconductor. It has been found that there is a risk of causing white spots after the stop and restart due to the movement and adhesion.
[0012]
Therefore, the present inventors have proposed a charging method in an atmosphere replaced with carbon dioxide gas. Furthermore, various methods were proposed in which the substituted carbon dioxide gas could stay in the discharge region for a long time.
[0013]
However, even if the residence time of the carbon dioxide gas is lengthened, there is a flow path for the carbon dioxide gas to escape, so that there has been a problem that the air is replaced again by air due to convection with external air for a long time.
[0014]
In order to solve this problem, the present inventor has newly proposed a reduced-pressure charging system capable of forming a closed space in a discharge region, reducing the pressure in the closed space to facilitate discharge, and increasing charging efficiency. .
[0015]
[Problems to be solved by the invention]
However, the contact charging method uses a discharge in a gas when the charging method is not the charge injection method.However, the corona discharge phenomenon is governed by the magnitude of the discharge starting voltage based on Paschen's law, and the charged member is charged. If a part is exposed by a conductor such as a metal, this part is likely to be discharged, and there is a possibility that no charge is placed on a desired part of the photoconductor.
[0016]
Therefore, an object of the present invention is to provide a contact charging device for better charging in this reduced-pressure atmosphere.
[0017]
[Means for Solving the Problems]
In order to achieve the above object, an invention according to claim 1 includes a member to be charged used in an image forming apparatus such as a copying machine, a facsimile, a printer, a charging member for charging the member to be charged, the member to be charged, A closed space forming member forming a part of the closed space together with the charging member; and a side plate having a space surrounded by the charged member, the charging member and the closed space forming member as a closed space, and a discharge atmosphere in the closed space. In a contact charging device for charging a member to be charged by a charging member by decompressing a gas, at least a portion of the surface of the member to be exposed exposed to the closed space is coated with a dielectric substance. In this configuration, since the surface of the member to be charged is covered at least with the dielectric material at the portion exposed to the closed space, the bias of the discharge due to the exposure of the conductor can be prevented, and the desired portion of the member to be charged can be prevented. Can be charged.
[0018]
According to a second aspect of the present invention, in the contact charging device according to the first aspect, the charging member and the closed space forming member are each made of an elastic body. In this configuration, since the charging member and the closed space forming member are each made of an elastic body, high confidentiality can be maintained.
[0019]
According to a third aspect of the present invention, in the contact charging device according to any one of the first to second aspects, the member to be charged, the charging member and the closed space forming member are all formed of a rotating body, and the rotation of the member to be charged is performed. The shaft, the rotation axis of the charging member, and the rotation axis of the closed space forming member are arranged parallel to each other. In this configuration, the member to be charged, the charging member and the closed space forming member are all formed of a rotating body, and the rotation axis of the member to be charged, the rotation axis of the charging member and the rotation axis of the closed space forming member are arranged in parallel with each other. Therefore, a closed space surrounded by the rotating body can be formed.
[0020]
According to a fourth aspect of the present invention, in the contact charging device according to any one of the first to third aspects, the dielectric material is made of an organic photoreceptor. In this configuration, since the area to which the organic photoreceptor is attached is only enlarged, the device can be manufactured without increasing the number of manufacturing steps.
[0021]
According to a fifth aspect of the present invention, in the contact charging device according to any one of the first to third aspects, the dielectric material includes an organic photoreceptor portion and a dielectric portion different from the organic photoreceptor. It is characterized by. In this configuration, since the dielectric material is composed of the organic photoreceptor portion and the dielectric portion different from the organic photoreceptor, the use of the organic photoreceptor material can be minimized.
[0022]
According to a sixth aspect of the present invention, in the contact charging device according to the fifth aspect, the dielectric portion different from the organic photoreceptor is an inorganic dielectric portion. In this configuration, the dielectric portion different from the organic photoreceptor is an inorganic dielectric portion, so that the use of the organic photosensitive material can be minimized without using an organic dielectric.
[0023]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a front view of a contact charging device according to an embodiment of the present invention, and FIG. 2 is a diagram showing a positional relationship of rollers of the contact charging device according to the embodiment of the present invention.
[0024]
As shown in FIG. 1, the contact charging device includes a drum photoreceptor 2 which is a member to be charged, a charging roller 1 which is a charging member which contacts and charges the drum photoreceptor 2, a drum photoreceptor 2 A closed space forming roller 3 which is a closed space forming member that shields a space between the roller 1 and the side plate 4 is provided. The side plate 4 is provided with an atmosphere gas supply port (not shown).
[0025]
Since the rotating shaft 2a of the drum photosensitive member 2, the rotating shaft 1a of the charging roller 1, and the rotating shaft 3a of the closed space forming roller 3 are arranged in parallel with each other, a closed space S is formed.
[0026]
The drum photoreceptor 2 uses an aluminum drum as a conductive support, finishes its surface in a mirror-like manner, and applies a photosensitive layer made of an organic photoreceptor (OPC) which is a dielectric substance to the end of the conductive support. It is constituted by vapor deposition or coating and coating. In the present embodiment, the photosensitive layer includes a charge generation layer (CGL) formed on a conductive support and a charge transfer layer (CTL) laminated on the charge generation layer, which is a so-called CTL upper layer system ( (Laminated type).
[0027]
In the present embodiment, the OPC photosensitive layer is coated up to the end of the conductive support. For example, the area (the area not charged by the charging roller 1) 2b outside the closed space shown in FIG. 1 is different from the OPC photosensitive layer. An organic dielectric or an inorganic dielectric may be used.
[0028]
The photosensitive layer includes a charge transfer layer (CTL) formed on a conductive support and a charge generation layer (CGL) stacked on the charge transfer layer, which is a so-called CGL upper layer system (stacked type). It may be. Further, in the above embodiment, the end of the conductive support is covered with the organic photoreceptor, but the portion where the charging roller 1 does not contact is, for example, a dielectric material other than the organic photoreceptor, for example, an organic dielectric or an inorganic dielectric. There may be.
[0029]
The charging roller 1 is formed in a roller shape having a cored bar as a rotating shaft 1a, and as described above, the rotating shaft 1a of the charging roller 1 and the rotating shaft 2a of the drum photosensitive member 2 are arranged in parallel. .
[0030]
The closed space forming roller 3 is formed in a roller shape having a cored bar as a rotating shaft 3a. The rotating shaft 3a of the closed space forming roller 3, the rotating shaft 2a of the drum photosensitive member 2, and the rotating shaft 1a of the charging roller 1 are connected to each other. Are arranged in parallel with each other, and the drum photosensitive member 2, the charging roller 1 and the closed space forming roller 3 are in line contact with each other.
[0031]
Side plates 4 are arranged at both ends of a space surrounded by these three rotating bodies 1, 2, 3 respectively, and a closed space S is formed by the three rotating bodies 1, 2, 3 and the side plate 4. In order to maintain the confidentiality of the closed space S, the surfaces of the rotating bodies 1, 2 and 3 need to be in contact with each other so as to be smooth and leak-free, and the rotating shafts 1a, 2a and 3a are required to rotate. It is necessary that the degree of parallelism is excellent and that each rotation has no unevenness.
[0032]
Further, in order that the rotors 1 and 2 are brought into close contact with each other so that no gap is generated with the rotation, it is preferable that at least two of the rotors 1, 2, and 3 are not rigid but elastic.
[0033]
(Example 1)
An image forming apparatus in which a charging section is enclosed by a side plate and a charging roller, a drum photoreceptor, and three rotating members of a closed space forming roller, wherein a charging section is a closed space. It is formed of hydrin rubber. The drum photoreceptor is an organic photoreceptor in which the charge transfer layer uses a polycarbonate resin as a binder, and the entire surface of the drum photoreceptor at a portion where the charging roller contacts is covered with the organic photoreceptor so that the conductive portion is not exposed. An image was formed on the drum photoreceptor. (Sample No. 1)
[0034]
(Comparative Example 1)
Although the layer configuration and the like of the contact charging device of Example 1 and the drum photoreceptor are the same, the portion substantially unnecessary for image formation in the copying process is formed in a shape in which the conductive support is intact and the image is formed. Was. (Sample No. 2)
[0035]
(Comparative Example 2)
Although the contact charging device of Example 1 has the same layer configuration as the drum photoreceptor, the charging roller and the closed space forming roller are formed by forming an inelastic fluororesin PFA (perfluoroalkoxy resin) on a cored bar. Configure. The drum photoreceptor is an organic photoreceptor in which the charge transfer layer is made of a polycarbonate resin as a binder, and the entire surface of the drum photoreceptor at a portion where the charging roller contacts is covered with the organic photoreceptor so that the conductive portion is not exposed. An image was formed on the drum photoreceptor. (Sample No. 3)
The above results are summarized in Table 1 below.
[0036]
[Table 1]

[0037]
By coating the conductive support in this way, the disturbance of the discharge is prevented, the charge becomes uniform and a good image can be obtained, and the disturbance of the discharge state is caused by maintaining the confidentiality during the charge. A good image can be obtained.
[0038]
【The invention's effect】
As described above, according to the contact charging device of the invention of claim 1, a member to be charged used in an image forming apparatus such as a copying machine, a facsimile, a printer, a charging member for charging the member to be charged, A closed space forming member that forms a part of a closed space together with the charged member and the charging member; and a side plate that defines a space surrounded by the charged member, the charging member and the closed space forming member as a closed space, In a contact charging device in which a discharge atmosphere gas in a space is decompressed and a member to be charged is charged by a charging member, at least a portion of the surface of the member to be exposed exposed to the closed space is covered with a dielectric substance, The bias of the discharge due to the exposure of the body can be prevented, and the charge can be placed on a desired portion of the charged member.
[0039]
According to the contact charging device of the second aspect of the present invention, in the contact charging device of the first aspect, the charging member and the closed space forming member are each made of an elastic body. , Can maintain high confidentiality.
[0040]
According to the contact charging device of the third aspect of the present invention, in the contact charging device according to any one of the first to second aspects, the member to be charged, the charging member and the closed space forming member are all formed of a rotating body, The rotation axis of the member to be charged, the rotation axis of the charging member, and the rotation axis of the closed space forming member are arranged in parallel with each other. An enclosed closed space can be formed.
[0041]
According to the contact charging device of the invention of claim 4, in the contact charging device of any one of claims 1 to 3, the dielectric substance is made of an organic photoreceptor. In addition to the effects described in Crab, it can be manufactured without increasing the number of manufacturing steps.
[0042]
Further, according to the contact charging device of the invention of claim 5, in the contact charging device according to any one of claims 1 to 3, the dielectric substance includes an organic photoconductor portion and a dielectric portion different from the organic photoconductor. Therefore, in addition to the effects described in any one of claims 1 to 3, the use of the organic photosensitive material can be minimized.
[0043]
According to the contact charging device of the invention of claim 6, in the contact charging device of claim 5, the dielectric portion different from the organic photoreceptor is an inorganic dielectric portion. In addition to the effects, the use of organic photosensitive materials can be minimized without the use of organic dielectrics.
[Brief description of the drawings]
FIG. 1 is a front view of a contact charging device according to an embodiment of the present invention.
FIG. 2 is a diagram showing a positional relationship between rollers of the contact charging device according to the embodiment of the present invention.
[Explanation of symbols]
REFERENCE SIGNS LIST 1 charging roller 2 drum photoreceptor 3 closed space forming roller 4 side plate

Claims (6)

A member to be charged used in an image forming apparatus such as a copying machine, a facsimile, a printer, etc., a charging member for charging the member to be charged, and a closed space forming part of a closed space together with the member to be charged and the charging member A member , and a side plate having a space surrounded by the member to be charged, the charging member and the closed space forming member as a closed space, and depressurizing a discharge atmosphere gas in the closed space to charge the member to be charged by the charging member. In the contact charging device,
A contact charging device, wherein at least a portion of the surface of the member to be charged exposed to the closed space is coated with a dielectric substance. 2. The contact charging device according to claim 1, wherein the charging member and the closed space forming member are each made of an elastic body. The member to be charged, the charging member and the closed space forming member are both formed of a rotating body, and the rotation axis of the member to be charged, the rotation axis of the charging member and the rotation axis of the closed space forming member are arranged parallel to each other. The contact charging device according to any one of claims 1 to 2, wherein 4. The contact charging device according to claim 1, wherein the dielectric material is made of an organic photoreceptor. 4. The contact charging device according to claim 1, wherein the dielectric material includes an organic photoreceptor portion and a dielectric portion different from the organic photoreceptor. 6. The contact charging device according to claim 5, wherein the dielectric portion different from the organic photoreceptor is an inorganic dielectric portion.

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