JP2002148901A - Electrifying device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrifying device which does not generate ozone or the like, has a long service life, seldom damages a body to be charged, and enables an efficient electrifying. SOLUTION: In an electrifying device, having a brush-shaped surface which makes contact with the body to be charged, the functions of wires are separated by the radius of each wire so that stress applied to the electrifying device is absorbed by thicker support wires 112 with suitable elasticity and thinner wires 113 have a function to contribute to the electrification.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a charger, and more particularly to a charger having improved charging efficiency.

[0002]

BACKGROUND OF THE INVENTION The present invention relates to a contact type charger used for an image recording apparatus such as an electrophotographic copying machine, a printer, a facsimile or the like. It can be applied to various devices. The following is an example of an application.

(1) Ionizer In a liquid crystal factory or the like, an ionizer is used to prevent static electricity. Conventional ionizers utilize the aerial phenomenon. For this reason, foreign matter is generated from the electrodes, which is a factor that lowers the yield. By using the charger of the present invention as a static eliminator, static elimination without generating foreign matters is enabled. When removing the normal charge of the substrate, the thin line portion of the charger of the present invention is brought into contact with a charged substrate or the like.
Although the direct object and effect of the present invention is to positively charge the battery, it is expected that a static elimination effect can be expected by keeping the ground without applying a voltage. Basically, no foreign matter is generated from the charger. At the same time, it can be expected that foreign substances existing on the substrate are adsorbed to the charger.
In this case, it is necessary to configure a device for removing foreign matter on the charger side.

(2) Electrode of Electric Double Layer Capacitor Although the discharge phenomenon is slightly different from that described above, the discharge phenomenon between the electrolyte and the electrode can also utilize the high surface property of the charger of the present invention. it can. An electric double layer capacitor is a capacitor that stores electric charges on an electrode surface as an electric double layer. The capacitance is determined by the dielectric constant, thickness, and area of the capacitor. At present, this capacitor is used as an auxiliary power supply at the time of a power failure, but if a larger capacity can be obtained, application to, for example, an electric vehicle can be considered. In order to increase the capacity, it is necessary to consider the above-mentioned three factors, that is, the dielectric constant, the thickness, and the area. At present, a high-area material such as activated carbon is used. However, the area ratio of activated carbon has already reached its limit, and a material having a higher surface area is required. In this sense, the charger of the present invention is configured for the purpose of increasing the surface area, and is suitable for such an application. Further, in the current activated carbon, dangling bonds, hydrogen groups, hydroxyl groups, and the like are present on the surface of carbon, and there is a problem that gas is generated in the electrolytic solution due to an electric field applied for charge transfer. For such a problem, it is desired that the surface is also composed of a chemically stable substance. Also in this aspect, since the charger of the present invention uses carbon nanotubes,
The surface is very stable chemically. These advantages are:
The present invention is not limited to electric double-layer capacitors, but can be used as an electrode material for ordinary secondary batteries as an advantage.

(3) Gas (Hydrogen) Storage Material for Fuel Cell It has been experimentally shown that carbon nanotubes have a large gas storage capacity due to their large surface area, and have a larger storage capacity than ordinary hydrogen storage alloys. (Nature3
86 (1997), p. 376). In this case, the carbon nanotube is used only as a substance having a large surface area. For this reason, the carbon nanotubes used at this time are in a state of being randomly entangled without being particularly supported one by one. In the charger of the present invention, since the carbon nanotubes are supported one by one on the conductive thin wire, a potential can be applied to each of the conductive carbon nanotubes. That is, the formation of the high potential surface having a large surface area, which is the purpose of the present charger, is realized. By blowing ionized gas (hydrogen) onto the large area and high potential area, the gas can be positively adsorbed. Here, exchange of charges with hydrogen ions is performed. In the present invention, the effect of the charger which can apply a potential to a large area can be obtained. This allows
It seems that a larger volume of gas can be stored than conventional alloys and carbon nanotubes.

Here, let us return to the contact type charger used in the image recording apparatus. In the conventional charging system, a corotron using a corona discharge and a scorotron were mainly used.
However, corona discharge applies an electric field in the air,
Producing harmful substances such as ozone and NOx in large quantities,
High power consumption due to low charging efficiency, and 4-6 kV
However, there is a drawback that the high voltage power supply is required, so that the cost is high and there is a danger to the human body. It is urgent to improve such a charging system in consideration of environmental considerations in recent years, and there is a shift to roller charging. Roller charging is a method in which a conductive rubber roller is brought into contact with an object to be charged such as a photoreceptor in the case of an image recording apparatus, and discharge is caused in a minute gap between the object and the charging roller to charge the surface of the object to be charged. And ozone are significantly reduced (reduced to 1/100 to 1/500) as compared with Corotron. However, since the charging roller also applies a voltage to the minute gap between the member to be charged and the charging roller to cause corona discharge, the generation of ozone cannot be reduced to zero in principle. Further, since ozone is generated in the vicinity of the member to be charged, deterioration of the member to be charged due to ozone still remains as a problem. Therefore, a charging method that does not generate ozone at all is strongly desired, and charge injection has recently attracted attention.

[0007] Charge injection is a method in which charges are injected directly from a contact-type charger into a photosensitive layer without causing discharge. This method therefore does not generate ozone in principle. In charge injection, the lower the contact resistance, the better the contact resistance between the contact-type charger and the member to be charged and the capacity of the minute voids affect the injection speed at the time of charge injection.
To this end, Japanese Patent Application Laid-Open No. 6-75459 discloses a charge transfer complex composed of an electron accepting compound such as tetracyanoquinodimethane (TCNQ) and an electron donating compound such as tetrathiafulvalene (TTF). The charging roller is made of a conductive rubber made of a polymer material that has been entirely replaced with a molecular network and has conductivity. However, Japan Hardco by Kagawa, Furukawa, Shinkawa et al.
py'92, pp. 287-290 reports 80%
Under the high humidity of RH, the organic photoreceptor (hereinafter abbreviated as OPC) can obtain a sufficient charging voltage, but under the humidity of 30 to 50% RH, it is charged only up to half of the applied voltage and the injection speed is low. I know. This is probably because the contact area (nip width) of the charging roller is small and the resistance of the conductive rubber is not sufficiently reduced.

That is, in order to obtain a conductive rubber having a low resistance, it is necessary to dope a large amount of the charge transfer complex. However, as the doping amount increases, the flexibility of the network of the polymer itself decreases and the rubber hardness increases. I suspect that. For example, the resistance of the conductive rubber in Japanese Patent Application Laid-Open No. 6-75459 is 10 ⁶ Ω · cm, and reducing the resistance of the conductive rubber while maintaining an appropriate rubber hardness is as follows.
It is not expected to be easy in terms of selecting a polymer material.
Further, since the charging potential of a conductive rubber made of a polymer material having conductivity as a whole is sensitive to humidity, it is necessary to strictly control the environment, and the structure of the contact-type charger becomes complicated.

On the other hand, in Japanese Patent Application Laid-Open No. 7-140729, electric charges are injected into a photoreceptor using a water-absorbing sponge roller. When a water-absorbing sponge roller is used, the moisture content of the roller has a large effect on the roller resistance and the charge injection speed, and thus the charging potential may fluctuate due to evaporation of water from the roller. In order to suppress the fluctuation of the charging potential, it is necessary to strictly control the evaporation of water from the roller over a long period of time, and the structure of the contact-type charger becomes complicated and cannot be manufactured at low cost. In Japanese Patent Application Laid-Open No. 9-101649, the contact area between the conductive fiber and the photoconductor is increased by changing the conductive fiber of the charging brush to an etching fiber or a split fiber.
It has been proposed to increase the speed of charge injection. The etching fiber is a fiber obtained by dissolving a part of the component of the conductive fiber with a chemical solution and dividing one conductive fiber into a plurality of fibers in the thickness direction. In addition, the split fiber is a fiber obtained by splitting one conductive fiber in the thickness direction by utilizing a difference in heat shrinkage of each part at the time of heating. By these treatments, conductive fibers having a substantially smaller diameter are used, and the contact area with the photoconductor can be increased.

[0010] However, the tensile strength of the split fiber is smaller than that of the conductive fiber before the split by the split amount. As a result, when it comes into contact with the photoreceptor, the split fibers are easily cut, and when used for a long period of time, the charge potential varies, which causes a reduction in the life of the contact type charger. Conversely, when trying to obtain a long-life contact-type charger, the number of conductive fibers cannot be increased, so that a remarkable increase in the contact area cannot be expected, and the charge injection speed does not seem to be significantly improved.

[0011]

As described above, in the prior art, there is a method of dividing the charging brush. However, if the charging brush is simply divided, all the tips become fine lines. Normally, when the brush is pressed against the photoreceptor, the tip of the brush is bent or deformed against the pressing stress. In other words, all friction caused by pressing stress
It will be carried by this thin line. This inevitably reduces the life of the fine wire. In order to improve the life,
Fine wire diameter cannot be reduced too much. However, the contact area cannot be gained unless it is made thin. As a result, the charging ability of the conventional charging brush is low, and a sufficient charging potential cannot be obtained within a time. Further, as will be described later, it is desired that the fine wire for charge injection can be moved by Coulomb force. For that purpose, it is desired that the thin wire can be freely moved without external force. For this purpose, it is necessary to separate the function of the supporting fine wire that bears the stress generated when the charging brush is pressed against the photoconductor and the fine wire that injects the electric charge.

If the thin line does not come into contact with an uncharged area, charging failure occurs at that location. In order not to cause such charging failure, a thin line must be in contact with all regions. However, if the thin line is designed so as to stochastically contact all the regions, the amount of the thin line becomes enormous. At present, it is difficult to form a large number of fine wires in manufacturing. For this reason, conventional chargers have a roller shape,
By rotating at a peripheral speed of 3 to 4 times in the opposite direction to the member to be charged, the contact probability is increased. However, even if the contact probability is improved, actually,
The phenomenon that thin wires come into contact many times has occurred. Obviously, such a phenomenon would be very inefficient. A mechanism is required to prevent the thin line from coming into contact with the region where the contact has been made once and the charging has been completed. Also,
There is a need for a mechanism that allows the fine wire to positively contact the uncharged area.

Further, in order for the fine wire to move due to the Coulomb force, a mechanism for moving the fine wire must be built. Conveniently, the movement is such that the thin line occurs about a fixed point on the supporting thin line. For example, it is conceivable to create a mechanism in which the thin wire bends at this fixed point.
However, the thin wires considered at present are very thin and are on the order of microns or nanometers. Therefore, if stress is concentrated at one location, there is a problem in the strength of the thin wires. Since the object of the present invention is to extend the life, it is necessary to add this function so that the thin wire is not damaged as much as possible. For that purpose, there is a problem with a mechanism that bends at one place, and it is necessary to solve such a problem.

Further, the conventional charging brush has a small brush density and cannot obtain a sufficient charging ability. For this purpose, a brush provided with a thin wire has been devised. However, if the fine line of the brush does not have a sufficient length, charging in a region where the fine line does not reach is also poor. When the brush is formed, when the bundle of the supporting fine wires is fixed, there is a manufacturing limit in the density. It is necessary to take measures to increase the area of the portion in contact with the member to be charged while fixing the supporting fine wire at the possible density. Therefore, it is necessary to set the density of the supporting fine wires and the length of the fine wires to appropriate values. Further, in the conventional charging brush, since the fiber diameter is larger and harder than the Coulomb force, the brush fiber cannot be moved by the Coulomb force. Also,
Conventional brush fibers themselves have been subjected to the stress of the pressing pressure with the member to be charged. That is, the brush fibers were pressed against the member to be charged, and were not in a state where they could move freely due to frictional force from the member to be charged.

In the present invention, since the supporting thin line bears the stress due to the pressing pressure with the member to be charged, the thin line does not receive a frictional force with the member to be charged. That is, the force applied to the fine wire is the same as the force fixed to the supporting thin wire, and the own weight can be almost ignored. The thin line, which is generally free except at the fixed point, moves to an equilibrium state in which an external force and an elastic force generated when the thin line bends are satisfied. This equilibrium state must be satisfied functionally. Specifically, when the thin wire is deflected by Coulomb force,
The wires must be sufficiently soft and free to move.
The effect on the force is defined by the elastic modulus resulting from the strength of the fine wire.

Further, a large friction is generated in the fine wire directly in contact with the member to be charged. In a state where such friction is applied, problems such as heat generation are likely to occur. We need to deal with this. In addition, electrostatic force is applied to the thin wire by charging. There is also mechanical damage due to friction. Resistance to such external influences is required. Further, the supporting fine wire of the brush charger is constantly in contact with the member to be charged due to the pressing pressure. According to this configuration, it is possible to draw an equivalent circuit composed of electrical resistance as shown in FIG. At this time, if the resistance of the supporting fine wire is smaller than that of the fine wire, a sufficient current does not flow to the fine wire, and there is a possibility that charging is incomplete. Even if charging can be performed, the charging ability will be reduced.
In order to prevent such a problem from occurring, it is necessary to reduce the current flowing through the route between the supporting fine wire and the member to be charged as much as possible.

Further, the object to be charged has a photosensitive film of several tens μm formed on a conductive substrate. Although not a problem in normal image formation, small holes may be present in the photosensitive film. In the case of a contact charger, a short circuit occurs when a voltage is applied between the charger and the conductor base, and this hole becomes a pinhole, which is a problem. The pinhole causes deterioration of the member to be charged due to a large current flowing through the pinhole. In addition, there is a problem that the voltage applied to other contact areas is reduced. Even if a pinhole exists, it is necessary to prevent the voltage from being concentrated there.

As seen in the conventional charging roller, the amount of charge injection is limited even when the electrode portion of the charger is in direct contact with the member to be charged. It is said that this is due to discharge occurring between the minute gap between the charging roller and the member to be charged. It is expected that the transfer of charges caused by discharge is much faster than that of charge injection. It is said that the region where the discharge occurs is immediately before the rotating charging roller and the member to be charged come into contact with each other. There,
A minute gap exists between the charging roller and the member to be charged, and discharge occurs in the gap. As a result, the transfer of charges by the discharge occurs before the charge injection occurs.
After the discharge, if a sufficient potential is applied on the member to be charged, there is no need to send out the charges by further charge injection. As described above, the problem of ozone and NOx is caused by the occurrence of discharge. Further, if such a discharge occurs, the charge injection, which is the object of the present invention, cannot be performed satisfactorily.

Discharge occurs when a suitable gap and a suitable electric field are generated in air, as is known by Paschen's law. Such a condition may be satisfied by the charging process in the charging brush. For example, the tips of a plurality of charged brushes are not uniform in length on the order of microns. That is, some brush ends are in contact with the member to be charged, and some are not. The tip of the brush not in contact with the member to be charged is present with a gap of several μm from the member to be charged. As described above, discharge may occur in a normal charging brush, and a means for preventing the discharge is required.

The material of the fine wire portion of the charging brush must satisfy conditions such as nano-order fineness, conductivity, friction resistance (mechanical strength), flexibility, chemical stability, cost, and lubricity. Need to be. It is a major object of the present invention to find a material satisfying such conditions.

In view of the above, it is an object of the present invention to employ a charge injection method free from problems of ozone and NOx and to solve the problems of the conventional charging brush. Another object of the present invention is to minimize the wear of the charging brush and improve the mechanical life. Furthermore, the present invention not only increases the density of the fine wires (brush implantation density), but also increases the contact area between the fine wires and the object to be charged, thereby providing a configuration that enables efficient charging, thereby improving the charging ability. It is another object of the present invention to provide a configuration capable of solving the problems relating to pinholes and discharge.

[0022]

In order to solve the above-mentioned problems, the present invention provides a method for applying a voltage to a surface of a member to be charged by applying a voltage between the member and the charger. In a brush charger having a function of giving a predetermined surface potential, the surface of the charger in contact with the object to be charged is in a brush shape, and a plurality of types of radii of the line constituting the brush tip are present, the thicker line is used. (Hereinafter, referred to as support fine wires) absorbs the stress applied to the charger, and has a function of bending with appropriate elasticity so as to keep the distance between the brush and the charged device constant. And the thinner line (hereafter,
The function of each line is separated by the radius of each line so that the thin line contributes to charging. As a result, the function of the wire is separated into the support wire that carries the stress and the wire that injects the charge, and the charge injection method that does not generate ozone or NOx is adopted. It is possible to realize a charger capable of increasing the contact area with the member to be charged and enabling efficient charging.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a charger according to the present invention will be described in detail with reference to the accompanying drawings. First, the basic configuration of the present invention and its component parts will be described. This basic component is commonly used in all embodiments of the present invention. After that, a method of manufacturing each basic component and a method of joining each will be described. Finally, an embodiment of the present invention will be described.

1. Configuration of the Invention FIGS. 1 and 2 show an overall image of the basic configuration of the charger of the present invention. The charger includes a base 111, a support fine wire 112 fixed to the base 111, and a fine wire 113 fixed to the support fine wire 112. Reference numeral 114 denotes a fixing layer for fixing the supporting fine wire 112 to the base 111. Each part will be described in turn.

(1) Substrate The function of the substrate 111 is to conduct a current with conductivity and to firmly and firmly fix the thin support wires 112. Further, a certain pressure is applied between the base 111 and the member to be charged, whereby the supporting thin wire 112 bends with its elasticity at a portion in contact with the member to be charged, and a predetermined pressing pressure is applied. It is supposed to be. This pressure also needs to be uniform in the longitudinal direction of the member to be charged. Base 1
Since 11 is supported at the two end points in the longitudinal direction,
The mechanical strength of the base 111 itself is required to some extent so that the pressing force at the supported point and at a position distant therefrom does not change significantly.

Since the base 111 needs conductivity and strength, the base (main body) is made of resin to secure mechanical strength, and the base (main body) is configured to impart conductivity to the fixing layer 114. And the fixed layer 114 have a function-separated structure. The reason for choosing resin is that it has the appropriate strength,
It is also lightweight and inexpensive, is used in the housing of copiers, and is judged to be advantageous in terms of recycling. From such a viewpoint, the material of the resin is PC, ABS
For example, the same material as that of the copier housing or the like, which is easy to recycle, is preferable. Also, due to the required strength and weight reduction, it is necessary to devise its shape. However, not limited to such a resin, various materials can be used as a base material such as SUS, iron, a composite material with other metals, alloys, resins, and the like in terms of mechanical strength and cost. .

On the lower side of this resin base (on the side to be charged), a fixing layer 114 which is conductive and fixes the supporting fine wires is formed. Since adhesion to the resin substrate is required, the adhesion surface of the resin substrate was appropriately roughened. An ohmic contact is made from the longitudinal end of the fixed layer 114 to connect the wiring.
The wiring is taken from both ends of the fixed layer 114, and is devised so that the effect of the voltage drop due to the fixed layer does not appear in the charged state as much as possible. A voltage can be applied between the member to be charged and the fixed layer by the wiring. The material of the fixed layer is largely determined by the constraints of the manufacturing method. The contact with the supporting wire 112 is ohmic, and the contact resistance at this portion is reduced as much as possible. Therefore, this time the support fine wire 11
A conductive resin, which was also used for No. 2, was applied. However, as long as the fixing layer has conductivity and can fix the supporting fine wire 112, a low melting point metal such as Al, Cu, Au, or In, and other conductive resins can be used.

(2) Support Thin Wire The support thin wire 112 is fixed to the base 111, and the thin wire 113 is fixed at the tip, and the stress applied between the base 111 and the member to be charged must be supported by its elasticity. No. FIG. 5 shows an image of a state in which the support fine lines 112 are functioning. The support wire 112 must be appropriately bent by stress. Thereby, the object to be charged and the thin wire 113
Can be adjusted to be as short as possible. In this case, the support fine wire 112 only needs to partially contact the member to be charged and support the stress.
Need not actively contact the object to be charged with a large area. As the contact area increases, the contact resistance can be reduced and the charging ability can be improved. However, this function is performed by the thin wire 113 described later, so that it is not necessary.

Since the fine line 113 does not have a sufficient length, the distance between the fine line 113 and the member to be charged should be as short as possible. For this purpose, the supporting thin wire 112 needs to be bent as shown in FIG. 5 described above. Support wire 112
In order to bend as described above, the pressing force and the supporting wire 112 are required.
It is necessary to optimize the flocking density and the strength (elastic force) of the support fine wire 112. The elasticity of the support wire 112 is determined by its length, thickness, material, and the like. This time support wire 112
Was made of nylon. In addition, PET, PES, elastic epoxy resin, polyvinyl alcohol, vinyl chloride, and the like are considered to be suitable as long as they are easily formed into a fiber shape. Further, the charger of the present invention can be formed without being limited to such materials.

It is necessary to devise the supporting thin wire 112 so as to have conductivity and not to have a large contact resistance between the fixed layer and the thin wire. For this reason, a conductive nylon resin was used as the material of the support fine wire 112. As a method of imparting conductivity to a resin, there is a method of dispersing carbon black or metal particles. This time, we took a method of adding impurities such as TCNQ and TTF to the polymer network.
These methods can obtain conductivity more finely and uniformly. In the method using carbon black or metal particles, it is not possible to obtain non-uniform dispersion of the conductive fine particles or at least uniformity of the particles or less. As a result, some of the immobilized fine wires may not have conductivity with the base 111 depending on the distance from the conductive particles. In image charging, the order of submicron or less can be neglected. However, the thin line 113 of the present invention may be thinner by one to two orders of magnitude. Therefore, non-uniformity in this order should be sufficiently considered. There must be.

It is desirable that the resistance value of the supporting thin wire 112 is larger than the resistance value of the member to be charged. This is necessary as a measure against pinholes of the member to be charged, so that even if the fine wire 113 contacts the pinhole of the member to be charged,
Charge concentration there can be avoided. When the resistance value of the charger is controlled by the thin support wire 112, the area of voltage drop that occurs when the charger comes into contact with the pinhole can be reduced. As shown in the equivalent circuit of the charging device and the photosensitive member (charged member) in FIG. 8, the resistance at the pinhole is eliminated, and writing can be performed by an equivalent circuit with this portion short-circuited.

For example, when control is performed at the base of the charger, a short circuit in one part causes a voltage drop in the entire charger. On the other hand, when the resistance is controlled by the supporting thin line 112, other than the supporting thin line 112 supporting the short-circuited thin line 113 is not affected. That is, assuming that the respective resistance values of the support fine wires 112 are R1 to R4 in FIG. 8, if R1 to R4 are sufficiently large, even if a pinhole is formed, the resistances R1 to R4
There is no change in the value of 4 and the voltage can be applied normally. This does not affect areas other than the resistor R1. In other words, the effect of the pinhole does not cause a serious problem, since it only slightly changes the resistance value of the portion of the support wire 112 corresponding to the pinhole. Fine line 113
Although it is possible to control the resistance in this way, this method is difficult as a practical matter.

The contact resistance between the thin wire 113 and the member to be charged can be controlled by the material of both. The value greatly differs depending on what kind of material is in contact. As a practical matter, it is difficult to theoretically control the contact resistance.
A suitable contact resistance is obtained between the current object using the thin wire 113 and the object to be charged. The method of measuring the contact resistance is actually experimentally performed, and the method will be described below. This time, the evaluation chip has the same shape and dimensions so that the term of the area can be ignored. This time, a chip of 1 cm square is made, and the thickness of each material is defined on the base 111 made of brass. At the same time, the bulk resistance of this material is calculated by four-terminal resistance measurement. Using the thus-prepared evaluation chip, the object to be charged or a PET film simulating the object is actually charged. The charging speed at this time is measured. This charging speed is determined by the following equation.

Vs (t) = Va × [1-exp ｛−t /
(Rc + Rbb) C｝] where Rc is the contact resistance value, Rbb is the resistance value of the charger,
C is the capacity of the member to be charged. By performing the evaluation in this manner, the magnitude of the contact resistance can be evaluated. By such an evaluation method, the contact resistance Rb of the supporting fine wire 112 was made much higher than the contact resistance Rs of the fine wire 113. TCNQ and TT doped in the supporting wire 112
By changing the amount of F, the contact resistance can be controlled. Thus, the condition of Rb> Rs was created. The shape of the support fine wire 112 is determined from the viewpoint of making the fine wire 113 as thin as possible and providing it at high density in consideration of the charging ability of the charger. Thereby, the contact resistance generated between the charger and the member to be charged can be reduced. In order to make the thin wires 113 thinner and to have a higher density, the supporting thin wires 112 also have specifications required.

One of them is that it is thinner. The portion where the support fine wire 112 is in contact is the charged object and the support fine wire 112.
Since there are many portions between which the thin line 113 is sandwiched, the portion is involved in charge transfer, but is a region where free movement of the thin line 113 is hindered. The free movement of the thin wire 113 is an important function for reducing the contact resistance in the present invention, and it is desired that the area where this is hindered is as small as possible. For such a reason, the support fine wire 112 is required to be designed to be as thin as possible, and to reduce the area where the support fine wire 112 is in contact with the member to be charged. The second of the specifications required for the supporting thin wire 112 is to increase the density. In order for the thin wire 113 to sufficiently contact the member to be charged, the following conditions must be satisfied.

[0036]

(Equation 3)

Here, S (book / mm ² ) is the thickness of the supporting fine wire 11.
2, R ₀ is the radius of the support fine wire 112, L is the fine wire 11
3 length.

In order to satisfy this condition, the supporting fine wire 11 is required.
2 or the length L of the thin wire 113 needs to be increased. However, when the thin wire 113 is lengthened, the life of the thin wire 113 is shortened by the stress applied to the thin wire 113. Therefore, it is desirable to increase the density S of the support fine wires 112 if possible. As described above, the supporting fine wire 1
It is desirable that the fine wire diameter of 12 is as thin as possible and that high density is desired. A charger that satisfies these two specifications as much as possible and can be manufactured is a charger that can be actually manufactured. As a manufacturing method, a simple method is desired so as to lower the cost. It is determined by a trade-off between these two specifications, and an object having an appropriate shape must be designed.

(3) Thin Wire The thin wire 113 is a thin support wire 1 fixed to the base 111.
12 refers to a very thin line that is firmly fixed by the surface or inside. The thin line 113 directly touches the member to be charged when charging, or through the air,
Transfer of electric charges to and from the charged object is performed. We believe that the transfer of the main charge occurs by direct contact. In this case, it is desired that the thin wire 113 and the member to be charged come into contact with each other on as many surfaces as possible. As a result, charges can be efficiently sent to the member to be charged. Further, since the thin wire 113 directly touches the member to be charged, a material having as little friction as possible is desired. Normally, in the case of a contact charger, the surface is processed with a material softer than the member to be charged so that the member to be charged is not damaged as much as possible. The surface of an organic charging member often used in an actual machine is particularly soft, and such consideration is important. In particular, in recent years, the thickness of the photoconductor layer for realizing high definition has been reduced. At present, the film thickness is about several tens of μm, but it is inevitable that it will be about several μm in the future. Further, the thickness that can be removed by the current cleaning blade is also said to be several μm, and it is necessary to change such a function in the future. In the market, there is a demand for a longer life of the photoconductor, and there is an increasing demand for a function of reducing damage to the photoconductor by the charger.

In order to prevent the photosensitive member from being damaged as described above, it is necessary to provide the charging device with lubricity. Many ordinary lubricants are in the form of a liquid such as oil, and a fixing process using a silicone oil or the like for a photoreceptor is well known. In this process, it is not impossible to use a liquid material such as oil between the charger and the photoconductor. However, problems such as image deletion, charging failure, exposure failure, and transfer failure, which are caused by the oil remaining on the photoconductor side, are considered. Thus, in the present invention, the charging device is provided with solid lubrication. Examples of the fixed lubricant include graphite, MoS ₂ , and Teflon (registered trademark).
A layered effect such as that shown in FIG. It is hard to say that the mechanism of the layered lubricity has been completely clarified,
Even with such a layered effect, there is no adverse effect on the photoreceptor.

Since the thin wire 113 also directly contacts the member to be charged, a material having lubricity is desired as the material. Carbon nanotubes are expected to have lubricity like graphite. In the previous report, although it is theoretical calculation, there is also a report that sliding friction is smaller than rolling friction due to a phenomenon that occurs on the nano order. In the case of the solid lubricant used in this charger, the rolling phenomenon cannot be used. In other words, it is unavoidable that sliding friction occurs, but it is possible to enhance such lubricity by making the thin line 113 thinner. In other words, it shows that making the thin line 113 thinner not only increases the contact area but also lowers the friction coefficient.

The thin wire 113 needs to have conductivity for flowing a charge when charged. The resistance value of the thin wire 113 is determined and designed based on the resistance of the member to be charged and the support thin wire 112. Although the total resistance value of the charger also appears in the above equation, a smaller value is desired from the viewpoint of improving the charging ability. Also, as a measure against pinholes, it is necessary to increase the resistance value on the charger side. As described above, it is more desirable to control the side closer to the photoreceptor with a thin line. In this case, this control is performed by the support thin wire 112, and the resistance of the thin wire 113 is designed to be as small as possible.

It is desirable that the contact resistance is as low as possible. The contact resistance largely depends on the material as described above. Further, even if the same material is used, it is expected that the material will change when the outermost surface state changes. It is well known that the outermost surface greatly changes even on the order of several nm. For example, it is well known that metal such as Al, which has a low resistance value and is inexpensive, usually forms a metal oxide on the outermost surface, and such a metal oxide contributes to contact resistance. I have experimentally tried an Al charging roller having a very low resistance value, but at this time the charging ability was very poor. It seems that the contact resistance due to the oxide on the surface is also caused. Inactive metals such as Au and Pt
Since it is difficult to form an oxide, it seems to be suitable for the thin wire 113 of the present invention. In other words, a material that is electrically stable as much as possible and that does not easily form an oxide or the like is desired even if it has conductivity.

The thin wire 113 needs very high strength. In particular, this property is important for improving the life. The stress applied to the thin wire 113 is almost completely removed by the support thin wire 112 due to the pressing force applied to the base 111 and the member to be charged. Other than that, it is largely due to Coulomb force generated between the member to be charged. As a result, the thin wire 113 is largely bent and moved, but the stress applied at that time is large. Since this stress is constantly applied when it is charged, it is necessary to have a strength that can withstand such stress. It is desirable that the thin wire 113 be made of a uniform material so that such a stress as bending is always uniformly applied to the thin wire 113 and the stress is not concentrated at one location. Speaking of extremes, it is desired that the lattices be arranged without defects, as in a uniform perfect crystal. In this sense, an inorganic substance having high purity and high crystallinity may be suitable. On the contrary, a structure having appropriate elasticity or restoring force and capable of eliminating stress may be used. For example, a material having a large elasticity such as rubber can relieve stress. This is due to the structure of the charger of the present invention, but the Coulomb force is not constantly applied.
Once the thin wire 113 comes into contact with the member to be charged and the charge is transferred, no force is applied thereafter, and the thin wire 1
The stress inside 13 is relieved.

As an element for shortening the life, there is a factor due to friction with the member to be charged. Basically, the thin wire 113 is in close contact with the member to be charged, and is pressed against the member to be charged by Coulomb force or the like. At this time, by providing a fixed lubricating action, friction is reduced as much as possible. In addition, the time that the Coulomb force is applied is not a long time, and when the transfer of the electric charge is completed, the attractive force is lost. As a result, the thin wire 113 is immediately separated from the charged body by vibration or impact due to rotation of the charged body. As mentioned earlier, thinner is better, but there may be a trade-off between the demand for this fineness and the demand for strength. In this connection, it is very important to search for a material having both sufficient thinness and strength.

Further, there is a method of charging a medium with 100 μm level iron particles or the like connected by magnetic force. Generally referred to as a charged magnetic brush, many studies have been made. In this case, the iron particles are connected by magnetic force, but the photoconductor side is free. When charging is performed in this state, the free end largely moves due to Coulomb force. This movement is attracted by the Coulomb force to an uncharged point, where a contact charge is applied. After that, when the charging is completed, it moves to the next area again. This is a very attractive mechanism as a high efficiency charging mechanism. The embodiment of the present invention is different from the conventional one in that this mechanism is added to a conventional charging brush.

To realize such a phenomenon, a thin line 1
13 needs appropriate elasticity. The elasticity of the thin wire 113 is determined by the Coulomb force. Here the thin line 113
The necessary elastic force was considered under the following model. As shown in FIG. 9, the thin line 113 and the photoconductor are located substantially in parallel at a certain distance x. This is the support wire 113
Has elasticity so that it can be substantially parallel to the photosensitive member as shown in FIG.
Is equal to the radius R ₀ of An applied voltage V1 is applied between the fine line 113 and the photoconductor to charge the photoconductor. The electric field generated by the applied voltage is calculated from the distance from the thin line 113 and the voltage by the following equation.

E = V1 / x

At this time, the thin line 113 is very thin, while the photosensitive member surface is considered to be infinitely wide.
It is assumed that a uniform electric field is generated between the thin line 113 and the photoconductor. The Coulomb attraction applied to the thin wire 113 by this electric field can be calculated as follows, assuming that the permittivity in air is ε ₀ .

F = ε ₀ rE ² At this time, for the sake of convenience, the thin line 113 was converted assuming that it was a parallel flat plate having a width of 2r. By the force obtained by this formula,
What is necessary is that the thin line 113 moves. At this time, the force opposing the force F depends on the elastic coefficient k of the thin wire. However, the elastic coefficient k defines the elastic modulus in the lateral direction at a distance of L from the root of the thin line as shown in FIG. Assuming that the elastic force at this point is Fa,

Fa = −ky Here, y is the distance when the thin line 113 moves vertically from a stationary point where the thin line 113 is straight without any external force. Accordingly, when F> Fa is satisfied from this equation, the thin line 113
Will be moved by Coulomb force. Therefore, the following equation

When kR ₀ <ε ₀ rE ² is satisfied, it can be said that the thin line 113 moves.

That is, when the electric field is converted into a voltage,

K <ε ₀ rV ² R ₀ ^-3 . For example, if V is 100 V (considering charging stepwise) and R ₀ is 50 μm and r is 30 nm,

K = 2.1E-2 [N / m] By the way, in the case of a carbon nanotube, 0.5 micron and a radius of 30 nm, k is equal to 0.1.
5 [N / m] was measured by Eric W. Wong et al.
science 227 (1997), 1971.

In general, the following formula holds for a cylindrical substance.

K = 3πr ⁴ E ₀ / (4 × l ³ ) where E ₀ is Young's modulus, 1 is the length of the substance, and r is the radius. From the above experimental results, in the case of a carbon nanotube with r = 30 nmφ, if α is defined as follows, k = α / l ³ α can be calculated to be about 6.25 × 10 ⁻²⁰ [Nm ² ]. From this estimation, if the carbon nanotube has a length of 1.5 μm, k is 1.85 [N / m]. This value sufficiently satisfies the above k <ε ₀ rV ² R ₀ ^-3 .

As an element required for the constituent material of the thin wire 113, there is a manufacturing cost. Although very thin materials have been considered at the research level, few materials have actually reached the production level as used in the present invention. However, in the present invention, the same level of cost performance is desired in consideration of a substitute for a normal corona charger or the like.

As described above, the requirements for fine wires are fineness (nano-order), conductivity, friction resistance (mechanical strength), flexibility, chemical stability, cost, and lubricity. Required material. Various materials such as metal whiskers, WS2 nanotubes, and CB nanotubes can be considered as materials satisfying such conditions. However, it is considered that carbon nanotubes have such characteristics in a well-balanced manner in all aspects.

(4) Carbon Nanotube As the name implies, carbon nanotubes are known for having a diameter on the order of nanometers and a length on the order of microns. Recently, carbon nanotubes were discovered by Sumio Iijima of the NEC Basic Research Laboratory in 1991. Was done. The material is a carbon graphite layer that is seamlessly formed into a cylindrical shape, and the layer also has various types from a single layer to several hundred layers. Further, there are various types such as a closed end including a five-membered ring of carbon or the like which is open as it is. Initially, its production method was based on the arc discharge method, but it has been made in large quantities by the CVD method or laser ablation method using a more efficient metal catalyst, and is becoming a familiar material. .

Research on basic physical properties has also been vigorously conducted since its discovery from its unique shape. In particular, its electrical characteristics are metallic or semiconductor-like.
Predicted from first-principles calculations. In addition, various things have been found in spite of its small size and difficult to evaluate, such as its extremely high mechanical strength and its return to its original state without breaking even when bent sharply. Further, since the surface is formed of a graphite layer, it is known that the surface is very chemically stable. On the other hand, the carbon nanotubes are appropriately dispersed in a resin such as an epoxy resin, and the adhesion between the carbon nanotube and the resin is considerably high, so that the resin can be fixed firmly. For this reason, although it is nano-sized,
Handling has become easier by embedding in resin. In addition, since the material is close to graphite, it has a potential as a solid lubricant. In addition, in previous reports, the friction coefficient in the nano order is smaller for sliding friction than for rolling friction. Although there have not been many reports on the lubricity of carbon nanotubes, they are expected to have high potential as a lubricant.

In terms of application, a high non-uniform electric field can be generated due to its large aspect ratio and conductivity, and it is attracting attention as a field emission source of a field emission type display. In addition, due to its high surface properties, it has also attracted attention as an electrode of a battery in which activated carbon or the like has been used or a gas adsorbing substance. As an example utilizing mechanical strength, there is a report that a resin is dispersed in a resin to strengthen the resin (O. Lourie APL 73 (1998) 352).
7) and a report on application to actuators in the micro world (Ray H. Baughman Science 284 (19)
99) and 1340).

The elastic modulus of the carbon nanotube is as shown in Osaka Prefectural University (Proceedings of the 46th JSAP 29aH5).
And the like, but is usually measured by a method using SPM (scanning probe microscope) or the like. From such a database, it is confirmed that k is equal to or less than 6e-8 [N / m] in the shape used this time. With this value of k, the function of bending the thin line 113 in the short direction works.

As described above, the carbon nanotube generally satisfies the requirements for the above-described fine wire, and the present invention considers that this material is optimal. In addition, the carbon nanotube generally satisfies the requirements for the above-described fine wire, and the present invention considers that this material is optimal. However, in the present invention, not all of the above requirements have to be satisfied, so that not only carbon nanotubes but also other carbon fibers, WS nanotubes, C
Any ultra-fine fiber such as a B nanotube, a SiC nanotube, or a metal whisker can be used.

2. Manufacturing Method Here, a method for manufacturing a carbon nanotube will be briefly described. Single-walled carbon nanotubes are made of Fe, Co, Ni, Ru, Rh, Pd, O
A composite rod mixed with a metal medium such as s, Ir, Pt, La, and Y is used, and a graphite rod is used as a cathode.
00 to 700 Torr (1.33 × 10 ⁴ Pa to 9.3)
It is synthesized by arc discharge in an atmosphere of 1 × 10 ⁴ Pa) or He or H ₂ . The single-walled carbon nanotube exists in soot on the inner wall of the chamber (chamber soot) or soot on the cathode surface (cathode soot) depending on the type of the metal catalyst.

Further, the above composite rod was heated to 1000 to 1400 ° C. in an electric furnace, and was heated to 500 Torr.
Nd: YA in an Ar atmosphere (6.65 × 10 ⁴ Pa)
Light may be irradiated from a G pulse laser to synthesize single-walled carbon nanotubes. Since the synthesized single-walled carbon nanotube contains various impurities, it is preferable to purify the single-walled carbon nanotube to a purity of 80% or more by a hydrothermal method, a centrifugal separation method, an ultrafiltration method, or the like.

On the other hand, for the multi-walled carbon nanotubes, graphite rods were used for both the cathode and anode, and 100 to 700 T
It synthesize | combines using the arc discharge in He atmosphere of orr.
The multi-walled carbon nanotube is located at the center of the columnar deposit on the cathode. In addition, hydrocarbons such as benzene, ethylene, and acetylene are converted to 1000 to 1500 ° under a H ₂ gas flow.
Multi-walled carbon nanotubes can also be obtained by pyrolysis with C.

Since multi-walled carbon nanotubes also contain various impurities after synthesis, they are dispersed in an aqueous solution to which an organic solvent or a surfactant has been added, and then purified to high purity by a centrifugation method, an ultrafiltration method, or the like. Is good. Although carbon nanotubes are generally composed of only carbon atoms, some of the constituent atoms are replaced with other atoms, for example, B, N, Si
Even if it is substituted by, for example, it is included in the present invention as long as it has metallic or semiconductor conductivity. In addition, other atoms, for example, metal atoms, group III, and group V dopants may be sealed in the hollow tube of the carbon nanotube.

3. 1. Embodiment (1) FIG. 1 shows an outline of a basic configuration of an embodiment of the present invention. The charger includes the base 111, the supporting fine wires 112, and the fine wires 113. The configuration of the basic elements and the manufacturing method are as described above.

The base body 111 is manufactured by casting into a mold like a case of a usual copying machine or the like. ABS was used as the resin material to enable recycling. The shape is a fixed layer 114 molding surface is a rectangle of 300 × 10 mm,
On the back surface, a member that becomes a pillar was added to enhance the mechanical strength. Thereby, the thickness can be suppressed to about 10 mm. The fixing layer 114 is formed on the base 111 made of resin. The thickness of the fixed layer 114 is 500 μm
To the extent, apply by a coater. The above-mentioned nylon resin was used for the fixed layer. The nylon resin used this time has a low melting point and melts at about 100 ° C. Nylon was doped with TCNQ and TTF, respectively, and the bulk resistance was adjusted to about 10 ² Ω · cm. The base resin and the application conditions were selected so that the roughness of the applied surface was at the level of 50 μm. When the atmosphere is 100 ° C., the nylon coated in this way keeps a sufficiently molten state.

Here, a hot plate is placed on the back of the base 111 and heated at 130 ° C. from the base resin side. The atmosphere is maintained at about 80 ° C., and the surface of the fixed layer is increased in viscosity, but is almost in a state where it is not cured. Nylon fibers made individually are implanted in such a semi-molten nylon membrane. Nylon fibers to be planted have a diameter of 10 μm and a length of 2 mm. The resistance value of one nylon fiber is specified as 3 × 10 ³ Ω. As a result, assuming that the supporting fine wires 113 have a density of 120 lines / mm ² , the charging device is expected to have a resistance of 1 × 10 ⁹ Ω. This can be adjusted by the doping amount of TCNQ and TTF as described above.

Further, it has been confirmed that the fixing layer and the nylon fiber as the supporting fine wire 112 can make ohmic contact and have almost no contact resistance. This is an advantage of using the same type of material. Hair implantation was performed by a method using static electricity. After flocking, it is removed from the hot plate and cooled at room temperature to harden the nylon to form a solid. At this time, the support fine wires 112 are fixed to the fixed layer without melting and keeping the initial shape. Fixed layer 1
Although it is conceivable that the interface between the support wire 14 and the support fine wire 112 is slightly melted, the electrical resistance and the like can be firmly fixed without any problem.

At this time, the density at which the hairs are planted is 120 fibers / m.
specified in m ^2. The tips of the implanted support fine wires 112 are aligned so as to be uniform. The alignment can be made uniform by slowly contacting the metal surface heated to about 120 ° C. to melt and deform only the supporting fine wire longer than the other. Thus, the support fine wires 112 implanted have a uniform length with a variation of about 0.1 mm.

The electric conductivity and the contact resistance are measured in the state in which the thin supporting wires 112 are formed as described above. In this case, in this state, the IV curve measurement or the CV measurement is performed by contacting the metal electrode. Thereby, the supporting fine wire 112
Can be measured. The resistance this time was 1 × 10 ⁹ Ω for a 300 × 10 mm square. Since the resistance value of the photoconductor is the same size and 2 × 10 ⁸ Ω (volume resistivity 1 × 10 ¹² Ω · cm, thickness 50 μm), the resistance value Rbb of the supporting fine wire is compared with the charged object (photoconductor). )
Of the resistance Rph

The condition of Rbb> Rph is satisfied. This condition can be controlled by adjusting the value by changing the doping amount of the supporting fine wire 112 and the like.

Further, the thin support wire 112 is brought into contact with the photoreceptor, a voltage is applied between the photoreceptor and the charger, and the surface potential, the applied voltage and its time constant are evaluated. This makes it possible to evaluate the contact resistance between the support fine wire 112 and the photoconductor. The contact resistance obtained this time is 1 × 10 ¹⁰ Ω. By evaluating this value and the contact resistance when the carbon nanotube was generated, the contact resistance Rb of the support fine wire 112 to the member to be charged and the contact resistance Rs of the fine wire 113 to the member to be charged were measured.
Among

It is confirmed that the condition of Rb> Rs is satisfied.

The supporting thin wire 112 thus formed
Is implanted with carbon nanotubes. As a hair transplanting method,
This time, electrophoresis and immobilization with epoxy resin were adopted. This method has an advantage that carbon nanotubes can be arranged by Coulomb force. An epoxy resin having conductivity and being elastic at about 90 ° C. and having elasticity was used as the epoxy resin. The carbon nanotube is a multilayer type by arc discharge and has a length of 100
１５０150 μm and diameters of 10 to 25 nm were used. The carbon nanotubes were clustered by centrifugation, and finally, those having almost the same shape were selected.

The supporting fine wire 11 fixed to the fixing layer
2 is coated with an epoxy resin. The epoxy has a low viscosity in this manner and therefore feels like wetting the support wire 112. Also, because this epoxy has conductivity,
The support fine wire 112 can be used as an electrode. About 5 wt% of carbon nanotubes are dispersed in IPS and placed in a container having a size of 300 × 15 mm and a depth of 2.1 mm. The bottom of the container is made of conductive metal and has electrodes from the back. The support fine wire 112 coated with the epoxy resin prepared earlier is put on the container. Since the length of the support fine line 112 is uniform at 2 mm, it does not contact the lower electrode.

In this state, a voltage is applied to bring the carbon nanotubes into contact with the supporting fine wires 112 by electrophoresis. Take enough time to actually move and touch the IPS
Is heated and evaporated, and the epoxy is cured by baking. The density of the carbon nanotubes can be controlled by the concentration in the IPS dispersion, the application time and the applied voltage.

Basic Specifications (1) Substrate Dimensions: 300 × 10 × 10 mm, Material: ABS resin Pressing into photoreceptor: 0.5 mm Fixed layer material: Nylon resin doped with TCNQ and TTF Fixed layer width: 8 mm Fixed layer thickness : 0.5 mm (2) Support fine wire Diameter: 10 μm, length: 2 mm, density: 120 / mm
² Material: Nylon fiber doped with TCNQ and TTF (3) Carbon nanotube Diameter: 10 to 25 nm, Length: 100 μm or more Material: Multi-walled carbon nanotube Synthesis method: arc discharge Purification: Combination use of centrifugal separation method and ultrafiltration method ( 4) Conductive adhesive Material: Thermosetting epoxy conductive adhesive

The charging brush is connected to a DC power supply of -500 V, and is charged by contacting the OPC composed of CTL / CGL / hole injection blocking layer / A1 substrate. Since the peripheral speed of the photoconductor is 300 mm / s, the contact time between the charging brush and the photoconductor is 0.1 s. The photoreceptor was charged to -440 V while in contact with the charging brush, and it was confirmed that the charging brush in which the carbon nanotubes were connected to the conductive fibers had sufficient charging ability. The variation in the charging voltage in the longitudinal direction of the photoconductor was within 5%, and sufficient uniformity was obtained.

Embodiment (2) The feature of this embodiment lies in that an applied voltage is applied in steps as shown in FIGS. Charger is 3
Divided into two parts, with an insulating film 1 between each
15 to prevent electrical contact. The insulating film 115 was made of a flexible PET film and had a thickness of 0.5 mm. The length is the support wire 112
It was designed to be almost the same as the above, and not to touch the photoconductor. When the fixing layer 114 is applied, patterning is performed, and a gap of about 0.5 mm is formed between each part. The PET insulating film 115 has a fixing layer 114.
After the support fine wire 112 is planted, it is placed in the gap. An electrode is taken from each pinned layer portion, which makes it possible to apply a voltage to each portion independently. The respective electrodes are respectively −200 V, −400 V, and −500 with the back electrode of the photoreceptor grounded.
V was set.

Basic Specifications (1) Substrate Material: ABS resin, width: 2 mm, 3 blocks pressed into photoreceptor: 0.5 mm (2) Insulating film PET film: 0.5 mm thick (3) Fixed layer: Nylon resin doped with TCNQ and TTF (4) Support fine wire Diameter: 10 μm, length: 2 mm, density: 120 / mm
² Material: Nylon fiber doped with TCNQ and TTF (5) Carbon nanotube Diameter: 10 to 25 nm, length: 100 μm or more Material: Multi-walled carbon nanotube Synthesis method: arc discharge Purification: Combination of centrifugation method and ultrafiltration method ( 6) Conductive adhesive Material: Thermosetting epoxy-based conductive adhesive (7) Applied voltage -200V, -400V, -500V

The presence or absence of discharge is observed by the amount of ozone. Ozone was not detected at all, and it was confirmed that it was effective. The charging brush was connected to a DC power supply of -500 V, and was brought into contact with a photosensitive member composed of CTL / CGL / hole injection blocking layer / Al substrate to perform charging. Since the peripheral speed of the photoconductor is 300 mm / s, the contact time between the charging brush and the photoconductor is 0.1 s. The photoreceptor was charged to -440 V while in contact with the charging brush, and it was confirmed that the charging brush in which the carbon nanotubes were connected to the conductive fibers had sufficient charging ability. The variation in the charging voltage in the longitudinal direction of the photoconductor was within 5%, and sufficient uniformity was obtained.

[0086]

As described above, according to the first aspect of the present invention, a predetermined surface potential is applied to a member to be charged by contacting the surface of the member to be charged and applying a voltage to the member to be charged and a charger. In a brush charger in which the surface of the charger in contact with the member to be charged has a brush-like shape and the radius of the line constituting the brush tip is plural, the thicker line (supporting thin line) is charged. It has the function of absorbing the stress applied to the device, having the appropriate elasticity and flexing to keep the distance between the charging brush and the device to be charged constant, and the thinner line (fine line) is charged. The function of the line is separated by the radius of each line so as to have the function of contributing to the function.

As described above, the function is divided into the fine support wire for supporting the brush tip so as to keep the interval and the fine wire for charge injection. As a result, stress for supporting the brush is not applied to the thin wire, so that fatigue due to the stress does not accumulate on the thin wire, and the thin wire is less likely to break. Therefore, the strength required for the life is not required for the thin wire, and a thinner wire having a lower strength can be used. Since the fine wire is made thin, the fine wire can be contacted with the member to be charged with higher density, and the charging ability is improved. In addition, since the supporting wire bears the pressing stress, there is no need for a force that resists the fine wire, so the thin wire only needs to be strong enough to maintain itself, and a very soft elastic material etc. Options are expanded. Since the strength of a thin wire having a large contact area can be reduced, mechanical damage to the member to be charged can be reduced, and the life of the member to be charged can be improved.

The invention according to a second aspect of the present invention is characterized in that the length of the fine wire is sufficiently long with respect to the interval between the support fine wires, so as to fill the gap between the support fine wires. According to the invention of claim 3 of the present invention, the density of the support fine wire is S and the radius is R.
₀ and the length L of the thin wire,

[0089]

(Equation 4)

It is characterized in that the following condition is satisfied. With these, the distance between the supporting fine wires

[0091]

(Equation 5)

The length 2L of two thin lines (doubled since the thin lines cross from both sides) is longer than that of the two thin lines. That is, all the regions between the supporting fine lines can be filled with the fine lines. Therefore, there is no area where the thin line does not come into contact with the member to be charged, and there is no area with poor charging, and efficient charging can be performed.

According to the invention of claim 4 of the present invention, the thin wire constituting the tip of the brush has slidability. Thereby, the trouble due to friction can be eliminated.

The fifth aspect of the present invention is characterized in that the mechanical strength of one of the fine wires constituting the brush tip is greater than that of the other thin wires. Thereby, mechanical destruction can be prevented and the life can be prolonged.

The invention according to claim 6 of the present invention is characterized in that the current flowing from the fine wire to the member to be charged is larger than the current flowing from the supporting thin line to the member during charging. Also,
According to a seventh aspect of the present invention, the contact resistance Rb of the thin support wire to the member to be charged and the contact resistance Rb of the thin wire to the member to be charged are described.
and s with Rs. Although the equivalent circuit is drawn as shown in FIG. 6 in the past, the contact resistance is greatly involved in actuality, as shown in FIG. Therefore, by controlling the contact resistance in this way, the current flowing from the supporting thin wire to the member to be charged can be reduced,
Since the current does not flow through the supporting fine wire, all the current paths are caused to flow to the fine wire side. Thereby, the merit of increasing the area between the thin wire and the member to be charged can be exhibited, and charge injection can be performed efficiently. Thereby, efficient charging can be performed. The contact resistance can be controlled from the material, surface condition, and the like.

The invention according to claim 8 of the present invention relates to a method wherein the resistance Rbb is set between the resistance Rbb of the supporting thin wire and the resistance Rph of the member to be charged.
> Rph. As a result, even if there is a portion where Rph is extremely small, such as a pinhole, and the charger contacts there, it is possible to prevent charge concentration there.

According to the ninth aspect of the present invention, the distance between the member to be charged and the surface of the charger and the potential difference do not exceed the discharge voltage. The invention according to claim 10 of the present invention is characterized in that, within the nip region of the charger in contact with the member to be charged, the applied voltage V1 of the charger at the entrance side of the nip region and the voltage applied at the exit side of the nip region It is characterized in that there is a relationship of V1 <V2 with the applied voltage V2.

Thus, the potential difference between the charger and the member to be charged can be constantly adjusted freely. Discharge is a phenomenon that occurs only when a certain potential difference occurs. Therefore, the voltage is constantly adjusted to be equal to or lower than the discharge starting voltage. For example, when the discharge voltage is 300 V and the charging voltage is 500 V
If required, the conventional method naturally starts discharging when 500 V is applied. However, in the step voltage application according to the present invention, the voltage application is divided into three steps, and a voltage of 200 V is first applied to apply a voltage of 200 V to the surface of the member to be charged.
Charged to V. In the next block, 200V is applied further,
The potential of the member to be charged is added to 400V. In the last block, a further 100 V is applied, and finally 500 V can be obtained. In this process, the discharge starting voltage of 3
It can be charged at 500 V without exceeding 00 V.

As a result, the contact area can be improved, and the charging ability can be improved. In other words, in a normal charger, the object is rotated in a direction opposite to the rotating direction of the member to be charged to obtain a contact area. In this case, the charging brush must also form a rotating roller. In the roller shape, the applied voltage cannot be made stepwise in one roller. Therefore, in order to obtain a similar structure, it is necessary to make a plurality of rollers. However, it is difficult to insert a plurality of rollers while there is a demand for a more compact design.

The eleventh aspect of the present invention is characterized in that the fine wire is moved by the Coulomb force generated between the member to be charged and the charger, which is generated by the voltage applied to the charger for charging. And This allows the thin wire to move freely due to the Coulomb force due to the charged potential, thereby causing an attractive force to act on the uncharged area.
The thin line moves and comes into contact with the portion, and the transfer of electric charge is performed, and the uncharged region is charged. Further, a repulsive force due to Coulomb acts on the already charged area, and the thin line does not move in that area. Thus, if the fine wire can move freely by the Coulomb force, it can be charged efficiently. Further, since a constant voltage is applied to the fine wire even when the photoconductor is in contact, a voltage higher than a certain voltage is not applied to the photoconductor. As a result, unevenness of the charged potential does not occur, and image unevenness does not occur.

A twelfth aspect of the present invention is characterized in that the movement of the thin line occurs when the thin line bends in the lateral direction. In this way, the function of moving can be easily added, since the thin line itself bends more easily than the function of actively constructing the function. Since the configuration is simple, it is possible to obtain an advantage that it is inexpensive and hardly causes a failure. The stress applied to the thin wire during the movement is distorted by bending, and is not bent at one place, and breakage from that part is eliminated. Therefore, the life of the fine wire is extended. By bending, the sharp portion does not come into contact with the photoreceptor, but becomes soft contact, and damage to the photoreceptor is reduced. Further, due to this structure, the thin wire does not require strength. Therefore, a material that satisfies this condition and can be sufficiently bent can be selected.

According to a thirteenth aspect of the present invention, the tip of a thin wire is provided.
The elastic constant k in the lateral direction can be expressed as follows.
The radius of the thin wire is r, and the radius of the support thin wire is R₀ , Air permittivity
To ε ₀ And when

[0103]

(Equation 6)

The following condition is satisfied. Thereby, the functions described above can be easily obtained.
In order for a thin wire to move by Coulomb force, it is necessary to satisfy such conditions. When voltage is applied, the effect may be affected depending on the position where the fine wire exists, but at least the portion where the supporting fine wire is in close contact with the photoconductor under stress may be in a desired state. In addition, such a portion always exists stochastically, and this effect can be observed on average.

A fourteenth aspect of the present invention is characterized in that the fine wire is a carbon nanotube. It is known that carbon nanotubes are very thin due to their shape. In addition, it is known that the structure has high mechanical strength and is sufficiently bent from the size of the aspect. Also, it is known that even if it is sharply bent, it does not easily break (MRFalovo Nature 389 (1)).
997), p. 582). In recent years, the preparation method has become very simple, and it has become easier to obtain than other thin wires. Also, since carbon nanotubes are made of carbon alone, they are more environmentally friendly than fine wires such as whiskers made of noble metals. Furthermore, since the graphite is cylindrical in structure, there is no dangling bond on the surface. Thereby, it is chemically stable and does not form an oxide or the like on the surface.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a basic configuration of an embodiment of the present invention.

FIG. 2 is an enlarged view showing a basic configuration of the embodiment shown in FIG.

FIG. 3 is a rear view of another embodiment of the present invention.

FIG. 4 is a schematic diagram showing a basic configuration of the embodiment shown in FIG. 3;

FIG. 5 is an image diagram of the support thin line and the thin line during operation.

FIG. 6 is an equivalent circuit of a support fine line, a fine line, and a photoconductor.

FIG. 7 is an equivalent circuit of a support fine line, a fine line, and a photoconductor.

FIG. 8 is an equivalent circuit of a charger and a photoconductor.

FIG. 9 is a model diagram of a force applied to a thin line.

[Explanation of symbols]

 111 Substrate 112 Supporting Fine Wire 113 Fine Wire 114 Fixed Layer 115 Insulating Film

Claims (14)

[Claims] The present invention has a function of applying a predetermined surface potential to a member to be charged by contacting the surface of the member to be charged and applying a voltage between the member to be charged and a charger. In a brush charger where the surface of the charger that is in contact with the brush is brush-shaped and the radius of the line that constitutes the brush tip exists in multiple types, the thicker line absorbs the stress applied to the charger and has a suitable elasticity. And has a function to bend so as to keep the distance between the brush and the charged device constant (hereinafter, this fine line is referred to as a support thin line for convenience), and the thinner line (referred to as a thin line for convenience). Wherein the function of each line is separated by the radius of each line so that the charge contributes to charging. 2. The charger according to claim 1, wherein the length of the fine wire is sufficiently longer than an interval between the fine support wires so as to fill a gap between the fine support wires. 3. The density of the support fine wire is S, the radius is R ₀ ,
3. The charging device according to claim 1, wherein when the length of the fine wires is L, they satisfy the following conditions. 4. (Equation 1) 4. The charging device according to claim 1, wherein one of the fine wires constituting a brush tip has a sliding property. 5. The charger according to claim 1, wherein a mechanical strength of one of the fine wires constituting a brush tip is greater than that of the other thin wires. 6. The device according to claim 1, wherein a current flowing from said thin wire to said member to be charged is larger than a current flowing from said support wire to said member during charging. A charger according to any of the above. 7. The relationship between the contact resistance Rb of the thin support wire and the object to be charged and the contact resistance Rs of the thin wire to the object to be charged, wherein Rb> Rs. The charger according to claim 6. 8. The device according to claim 1, wherein a relationship of Rbb> Rph is established between the resistance value Rbb of the support thin wire and the resistance value Rph of the member to be charged. Charger. 9. The charging device according to claim 1, wherein an interval between the object to be charged and the surface of the charging device and a potential difference do not exceed a discharge voltage. 10. Inside the nip region of the charger in contact with the member to be charged, between the applied voltage V1 of the charger at the entrance side of the nip region and the applied voltage V2 at the exit side of the nip region. 10. The charger according to claim 9, wherein V1 <V2. 11. The method according to claim 1, wherein the fine wire moves by a Coulomb force generated between the object to be charged and the charger, which is generated by a voltage applied to the charger to perform charging. The charger described. 12. The movement of the thin line as the thin line bends in the lateral direction.
3. The charger according to 1. 13. The elastic constant k in the lateral direction at the tip of the thin wire is defined as follows: when the applied voltage is V, the radius of the thin wire is r, the radius of the supporting thin wire is R ₀ , and the dielectric constant of air is ε _0. 13. The charging device according to claim 12, wherein the following conditions are satisfied. (Equation 2) 14. The charger according to claim 1, wherein the fine wire is a carbon nanotube.