JP2002278219A - Body to be electrified, device and method for image forming and method for manufacturing electrifying device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a body to be electrified by which electrifying efficiency is improved, an image forming device using the body to be electrified and using a transfer device having an electric charge imparting material by which the deterioration of an image such as transfer scattering and image blurring is reduced while reducing a load to environment, the manufacturing method of an electrifying device and an image forming method. SOLUTION: In a system to perform electrification by directly or indirectly moving an electric charge from the surface of the electrifying device 5 to the surface of the body to be electrified 3, the number N (1/cm<2> ) of the trap level of the body to be electrified 3 per unit-area satisfies the condition of N>CV/q when C means a capacity (1/cm<2> ) per the unit area of the body to be electrified and V means desired voltage and q means an element electric charge.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a member to be charged, an image forming apparatus, a method for manufacturing a charger, and an image forming method used in an image recording apparatus such as an electrophotographic copying machine, a printer, and a facsimile.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 29, an electrophotographic image forming apparatus employs a photosensitive drum 10 as an image carrier.
00 is uniformly charged by the charging unit 1100, and the charged unit is charged with the exposure unit 12
An electrostatic latent image is formed by irradiating optical image information from 00, and the electrostatic latent image is developed with toner supplied from a developing unit (a developing roller in this case) 1300 to form a toner image. I do. Further, using a transfer device 1500 formed by applying a bias to a transfer roller 1400 made of a conductive roller using a conductive rubber or a dielectric roller having a dielectric layer provided on the conductive rubber, a transfer material p ( In this case, the toner image is transferred to recording paper. After that, the transfer material p is separated from the photosensitive drum 1000 by the charge removing device 1700. The separated transfer material is conveyed to a fixing device 1800 to fix the toner image, is stored in a discharge tray (not shown), and the photosensitive drum 1000 is cleaned by a cleaning device 1900.

[0003] The charging means 1100 for uniformly charging a member to be charged on the photosensitive drum 1000 generally uses a corotron or scorotron charging method using corona discharge. However, corona discharge generates harmful substances such as ozone and NOx because an electric field is applied to air. In addition, power consumption is high due to low charging efficiency.
Since a high-voltage power supply of up to 6 kV is required, the high-voltage power supply device is required in the circuit, and the cost is high. there were. It is an urgent need to improve such a charging system in consideration of environmental considerations in recent years, and it is being shifted to roller charging or the like.

[0004] Roller charging is a method in which a conductive rubber roller is brought into contact with a member to be charged, and discharge is caused in a minute gap between the member to be charged and the charging roller to charge the surface of the member to be charged. Significant reduction (1/10
0 to 1/500) (JP-A-7-926).
No. 17, JP-A-64-73365, JP-A-6-73365
4-54471, Japanese Patent No. 2584873, Japanese Patent No. 2744264).

However, 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, so that the generation of ozone cannot be reduced to zero in principle.
Although there are various theories as to the cause of deterioration of the member to be charged, one of them is that unnecessary products (ozone and NOx) due to discharge are chemically bonded to the surface of the member to be charged.
This is considered to be a strong oxidizing power of ozone or a nitride formed by NOx or the like. Also from such a thing, it is desired that unnecessary matter is not generated as much as possible in charging. Further, since the roller generates the ozone much closer to the member to be charged than the corona, the deterioration of the member to be charged by ozone still remains as a problem. Further, in recent years, a high electric field near the photoconductor has been suspected as a factor that deteriorates the photoconductor. In order to eliminate such concerns, a charging method at a low voltage is desired. Further, in principle, there is a certain threshold in the case of discharge, and charging cannot be performed unless a voltage is applied more than that. Therefore, for example, 1
If you want to charge to 00V, 150V for charge injection
On the other hand, discharge requires application of several hundred volts.
Even if future low-voltage development is realized, a voltage higher than the threshold must be applied, and the merit is diminished. If possible, a method that satisfies the condition with an applied voltage that is almost equal to the required surface potential is desired.

Incidentally, a film-type blade-type charger is known as a known technique. This also causes a discharge in the gap between the blade and the photoconductor. A feature of this is the flexibility of the film. Thereby, it is considered that the adhesiveness can be improved and uneven charging due to roughness of the photoreceptor can be reduced. However, film flexibility is a trade-off with its durability,
Practical issues remain.

[0007] Under such a background, a charger based on a charge injection method has attracted attention. Here, the charge injection means that the charges move directly or indirectly from the surface of the charger to the surface of the member to be charged. According to this charge injection method, ozone is not generated in principle because charges are directly injected into the photosensitive layer from the contact charger without causing discharge. 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.

For this reason, the technique disclosed in Japanese Patent Application Laid-Open No. 6-75459 discloses a high 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.

[0009] However, Kagawa, Furukawa, Shinkawa et al., "Japan Hardcopy '92, pp287-
290 ", an organic photoreceptor (hereinafter abbreviated as OPC) can obtain a sufficient charging voltage under a high humidity of 80% RH, but can be charged to only half of the applied voltage at a humidity of 30 to 50% RH. It has been found that the injection speed is low. This is presumably 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 think it is. For example, the resistance of conductive rubber in JP-A-6-75459 is 10 ⁶ Ωcm, and lowering the resistance of conductive rubber while maintaining an appropriate rubber hardness is necessary from the viewpoint of selecting a polymer material. Not expected to be easy. In addition, 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 the technique disclosed in Japanese Patent Application Laid-Open No. Hei 7-140729, a charge is injected into a photosensitive member (charged member) using a water-absorbing sponge roller. When a water-absorbing sponge roller is used, the water content of the roller has a large effect on the roller resistance and the charge injection speed, so that 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 photosensitive member is increased by changing the conductive fiber of the charging brush into an etching fiber or a split fiber, thereby improving the charge injection speed. It has been proposed to do so. The etching fiber is a fiber obtained by dissolving a part of the conductive fiber component 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, the conductive fibers having a substantially smaller diameter are used, and the contact area with the photoconductor (the object to be charged) can be increased.

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 the fiber comes into contact with the photoreceptor, the split fibers are easily cut, and if used for a long period of time, the charging potential varies, which causes a reduction in the life of the contact charger. Conversely, if a long-life contact-type charger is to be obtained, a significant increase in the contact area cannot be expected because the number of conductive fibers cannot be increased, and it is unlikely that the charge injection speed is significantly improved. As described above, some problems still remain in the charge injection method, and there are not many examples of application to an actual device.

Incidentally, Japanese Patent Application Laid-Open No. 2000-34 by the present applicant.
In the technology described in Japanese Patent No. 7478, a contact-type charger capable of giving a sufficient charging voltage to a member to be charged by using carbon nanotubes and reducing generation of ozone and NOx is disclosed. It does not mention the definition of the efficiency of charge injection into the body. Furthermore, in the contact type charger, since the charging roller and the photoconductor composed of the charged object are in contact with each other, if there is a pinhole in the photoconductor, the charging roller contacts the photoconductor at the contact portion (nip) between the charging roller and the photoconductor. Overcurrent flowed into the holes, the power supply voltage was lowered, sufficient charging could not be performed, and in-plane uniformity of charging was reduced.
In the worst case, the overcurrent may damage the photoconductor.

As a countermeasure against these problems, the journal of the Institute of Electrophotography, pp.
48-53 (1991) proposes that the charging roller has a three-layer configuration (see FIG. 27). The charging roller 2010 has a configuration in which a core material 2011 is covered with three layers of a protective layer 2014 / a middle resistance layer 2013 / a conductive elastic layer 2012, and a power supply 2003 in which DC and AC are superimposed is provided. Photoconductor pinhole and charging roller 201
When 0 contacts, the medium resistance layer 2013 prevents the voltage drop of the power supply 2003 due to the overcurrent in the pinhole.

In Japanese Patent No. 263168 (see FIG. 28), it is proposed to provide a coil 2120 between a photoreceptor 2100 (composed of a substrate 2101 and a photosensitive layer 2102) and ground. When the surface of the photosensitive layer 2102 is charged by the contact-type charger 2110 connected to the power supply 2103, if an overcurrent occurs due to a pinhole in the photosensitive layer 2102, the impedance of the coil 2120 becomes very large, and the overcurrent is applied to the photosensitive member 2100. Prevents inflow.

Similarly, in the transfer device of Japanese Patent No. 2788824, it has been proposed to provide a choke coil between the transfer device and ground. However, since the charging roller applies a voltage to the minute gap between the photoconductor and the charging roller to cause corona discharge, the generation of ozone cannot be reduced to zero in principle. In addition, since ozone is generated near the photoconductor, deterioration of the photoconductor due to ozone still remains as a problem.
From such a viewpoint, a charge injection method that is a charging method that does not generate ozone has attracted attention.

In the above-mentioned Japanese Patent Application Laid-Open No. Hei 6-75459, which is a technique employing a charge injection method, the conductive rubber of the charging roller is made of a polymer material having conductivity. In this example, electric charges are injected into a photosensitive member (charged member) using a water-absorbing sponge roller.
However, when the low-resistance contact charger as described above comes into contact with the pinhole, charge concentration occurs, and uniform charging cannot be performed. Especially in charge injection, since the charge is directly transferred at the contact portion (nip) between the photoconductor and the contact type charger, it has a fatal effect unlike the charging roller using corona discharge, and the image becomes blank I will. In addition, the photoconductor may be damaged by the overcurrent.

In order to prevent this, in Japanese Patent Application Laid-Open No. Hei 8-297394, charge is injected by bringing a medium-resistance member (resistance value 10 ⁴ to 10 ⁷ Ω) into contact with the photosensitive member. When charge injection is performed with a medium-resistance member, the injection speed becomes extremely slow. However, in Japanese Patent Application Laid-Open No. 8-297394, conductive fine particles are further dispersed on the surface of the photosensitive layer to create a floating capacity, thereby reducing the injection speed. The decline is suppressed. However, since the conductive fine particles are dispersed on the surface of the photosensitive layer, the absorption and scattering of light by the conductive fine particles are inevitable, which has been a factor in lowering the resolution and gradation of the image recording apparatus. Further, an organic photoconductor (OPC) using a conventional organic photoconductive layer cannot be used as it is, which has caused a cost increase for the image recording apparatus itself.

Alternatively, the technique used for the charging roller described above may be diverted to charge injection. However, when a coil is externally attached to a photoreceptor or a contact type charger, a contact portion (nip) of the contact type charger is used. When a pinhole in the photosensitive layer comes in ()), an overcurrent is generated, and it is considered that a voltage is gradually applied to the photoconductor by a time constant due to the self-inductance L of the coil and the resistance R of the charger. Since the size is very small (generally, the pinhole is on the order of μm), almost no voltage is applied to the photoconductor while the contact-type charger slides on the pinhole, and charge injection does not occur. Therefore, a line-like white spot occurs in the image.

When a contact-type charger having a medium-resistance layer inside is used, the resistance of the contact-type charger itself is determined by the medium-resistance layer and does not become low, so that the charge injection speed becomes very slow. In order to avoid this, it is necessary to disperse conductive fine particles on the surface of the photosensitive layer as disclosed in JP-A-8-297394, and there has been a problem that a high-resolution and high-gradation image cannot be obtained.

Next, an electrophotographic image forming apparatus applies an electric field to air in the same manner as a charger when transferring a toner image formed on a member to be charged of an image carrier onto a transfer material. A transfer type transfer device is used. This transfer device uses a transfer device 2332 of a corona wire 2331 provided in a holder 2330 as shown in FIG.
However, the transfer device 2332 using corona discharge requires a relatively large current by applying a high voltage, which not only increases the power consumption but also generates a large amount of ozone (O ₃ ) and knock (NOx). And have a significant impact on the environment. In order to remove these substances that affect the environment, such as adding a filter to remove ozone, the size of the apparatus is increased and the cost is increased.
For this reason, in recent years, a transfer device that does not use corona discharge has been put to practical use.

As one example, Japanese Patent Application Laid-Open No. 11-15391
No. 6 discloses a roller transfer device 1500 (see FIG. 29) known as a known technique. Roller transfer unit 150
No. 0 applies a bias to a transfer roller 1400 made of a conductive roller using conductive rubber or a dielectric roller having a dielectric layer provided on the conductive rubber, and the transfer roller 160
The toner image is transferred to a transfer material p (recording paper in this case) fed from 0.

A transfer brush known as a known technique in Japanese Patent Application Laid-Open No. 9-179413 also forms a toner image on a charged body of a photosensitive drum by the same process as described above. On the other hand, a transport belt composed of a film-like member having a thickness of about 100 μm and having a specific volume resistance,
They are arranged in a loop, slide on the photosensitive drum, and move sequentially. The recording material is electrostatically attracted to the transport belt and transported to a contact portion (hereinafter, a nip portion) with the photosensitive drum. A transfer brush is in pressure contact with the rear surface of the conveyor belt opposite to the photosensitive drum. The transfer brush is applied with a bias having a polarity opposite to that of the toner, so that the toner on the photosensitive drum is transferred to a recording sheet as a transfer body.

In these transfer rollers and transfer brushes, a minute space exists on the opposing photosensitive drum and conveyance belt.
Since a sufficient high pressure is applied to transfer to the transfer roller or brush, discharge in a small area in accordance with the Paschen rule cannot be avoided, and ozone and NOx are generated although the amount is smaller than that of the conventional corona discharge. It is feared that the ozone and NOx adhere to the photoreceptor, the transfer belt and the intermediate transfer belt and change into a substance that changes the surface resistance. For example, in JP-A-11-231661, the surface resistance of the transfer belt when not used and the surface resistance of the transfer belt after use for 100 hours are measured.
The surface resistance, which was × 10 ¹⁵ Ωcm, became 1.0 × 10 ¹¹ Ωcm after 100 hours from when the voltage was continuously applied,
It has been reported that the surface resistance decreases over time. This has been confirmed as the attachment of an ionized substance such as NOx generated by discharge when applying electric charge. Due to the lowering of the resistance on the back side of the belt, the electric charge originally held in a specific area of the transfer belt is diffused, causing a decrease in the potential of the nip portion. Yu "Transfer dust" increases. In a type in which a YMCK (yellow, magenta, cyan, black) toner such as full color is once transferred to an intermediate transfer member,
It is easy to imagine that the resistance of the intermediate transfer member changes, so that the toner retention decreases and the transfer dust increases.

In order to prevent such “transfer dust”,
In Japanese Patent Application Laid-Open No. H11-153916, it is possible to provide an electric field shield installed so as to cover the entrance side of the transfer material. Proposed. However, as a charge imparting material for each of these transfer devices, a corona wire using a corona discharge, a transfer roller, and a transfer brush are used, and it is not enough to prevent ozone and NOx from being generated, thereby preventing deterioration in image quality caused by the generation. It is.

[0027]

When the charging device of such an image forming apparatus employs an injection charging system for charging by directly or indirectly transferring charges from the surface to the surface of the member to be charged, the efficiency of the charging device is increased. Was not enough. here,
The efficiency is an index for examining how much the surface potential increases with respect to the applied voltage. For example, when the efficiency is very high, the slope n is 1. There are various factors that determine this efficiency. This time, we have found that trap levels play a major role among the various factors. Injection-type charging is different in physical phenomena from conventional charging using discharge such as a corona charger or a roller charger for wires. In the type using electric discharge, gas in the air is ionized by ionization. These ions fall onto the member to be charged. The ions that have reached the member to be charged are adsorbed at that point. Since the member to be charged is an insulator, no electric conduction occurs. That is, the ions can store the charge therein without being neutralized, and can exhibit the charge. Here, if the member to be charged is an insulator,
There is no particularly required physical property value.

On the other hand, in the case of injection type charging, electrons are moved. For an electron to move, its location, or level, is required. It can be seen that this is necessary when a tunnel phenomenon occurs. In the charging in the present invention, as well known in contact charging,
The movement of the electrons utilizes the tunnel phenomenon (see:
Static Handbook). This is a tunnel from the Fermi level on the charger side to the trap level of the member to be charged. In this case, if there is no trap level in the member to be charged, no tunnel current can flow. This is a well-known phenomenon, which is called STM (Scanning Tunneling).
Microscope). Such discussions have been actively conducted in recent years, and many researchers especially support such a model in the Electrostatics Society of Japan and the like. (Murata (Tokyo University of Science), Takeuchi (Ibaraki Univ.)). Taking this into consideration, the present invention takes into consideration how the state of the trap level is involved in increasing the charging efficiency.

The trap level keeps one electric charge per one. That is, the value obtained by multiplying the number of trap levels by the elementary charge q is the charge amount Q that can be stored in the charged body. However, this trap level has the property of its depth. The depth and the temperature of the environment define the trap time. For this reason, the trap levels in the present invention are shown to be sufficiently deep. For this reason,
It is considered that one trap level retains one charge and maintains that state unless a stimulus is intentionally applied. In a normal electrophotographic process, the time is a few seconds, and when used at room temperature, a trap level higher than the corresponding depth is indicated as a trap level. The accumulated charge amount of the charged body determined by the number of trap levels must be necessary for using the charged body. If there is no necessary trap level, no matter how much voltage is applied, efficient charging cannot occur.

As described above, the first object is to make the trap level contribute to the improvement of the charging efficiency of the member to be charged. Incidentally, the techniques dealing with trap levels in conventional reports are disclosed in JP-A-5-173391, JP-A-6-186766, JP-A-6-266136, and JP-A-6-27.
No. 3958, these are intended to reduce the optical memory effect caused by the level. In other words, the trap level governs the charging efficiency, and the number (density) of levels required for the trap level has not been dealt with.

Next, the member to be charged must hold the charged charge for an appropriate time. For this purpose, appropriate insulation is required. However, if there are many trap levels, electrons (holes) start to move between the traps, and the insulating property is reduced. This conduction mechanism is generally considered hopping conduction. Pool Frenkel conduction is also conceivable, but in this case it is very small,
It can be ignored. Hopping conduction has been well studied in semiconductors and the like, and its phenomenon is used in many situations. Based on such knowledge, a second task is to control the number of trap levels so that hopping conduction does not occur.

Next, in order to apply a negative charge to the member to be charged, it is necessary to trap electrons near the surface. On the other hand, in order to positively charge the member to be charged, a hole trap level is required on the surface. Neglecting this, even if the number (density) of trap levels is specified within a predetermined range, sufficient charge is not always sufficient. In other words, the third task is to set the type and number (density) of traps required in accordance with the polarity of the applied voltage in performing sufficient charging.

Next, as a charger for causing injection charging, G
a and examples of reports on hydrous rollers. However, such a charger has a problem in that constituent materials of the charger adhere to a member to be charged. Ga and mercury are used as a charger because they are conductive and liquid. There is a demand for a substance that does not maintain the properties of this liquid but does not cause a problem such as adhesion. Therefore, as a structure that satisfies such a condition, there is a surface shape body in which minute projections are formed at a high density. There are microprojections on the surface, which freely bend so that they contact and do not adhere like liquid. The surface of the charger provided with such a structure is subjected to mechanical shock such as contact with the member to be charged. In addition, since a structure that slides on the surface of the member to be charged is conceivable, slidability is also required. Considering various conditions, the requirements for protrusions used in the charger include fineness (high aspect ratio), conductivity, friction resistance (mechanical strength), flexibility, chemical stability, and cost, and slidability. A fourth object of the present invention is to find a projection that satisfies such a requirement and to provide an image forming apparatus using a charger including the projection.

Next, in the conventional roller-type charger, an arbitrary point on the charger-side surface comes into contact with only one fixed point on the member to be charged. If the point is a contact area, it is a contact point area, and if it is a gap area, it is a gap area. Even in the gap region, the surface potential varies depending on the size of the gap. That is, when the charger and the member to be charged come into contact with each other without slipping, unevenness in potential occurs due to the size of the gap. A fifth object of the present invention is to provide an image forming apparatus using a charger which can eliminate such image unevenness because potential unevenness becomes image unevenness as it is.

Next, since the blade type does not have a cleaner device, there is a possibility that toner or other small dust may enter between the charged body and the charged body. In such a state, formation of a uniform gap is hindered, which is a serious problem in image formation. Wherever possible, a process design that is resistant to such contamination is required. Also, even if CNTs are installed on the blade surface, their wear cannot be avoided. Also in the case of a blade, the resin fixing the CNT is scraped by contact with the member to be charged, and the CNT can be constantly exposed. However, since the control is determined only by the member to be charged and the fixed resin, an image using a charger having a configuration which is easy to control by suppressing such a change over time due to abrasion between the member to be charged and the member to be charged. A sixth object is to provide a forming apparatus.

Conventionally, a blade type or roller type charger has been considered. In the charger having such a shape, when a minute foreign substance such as toner enters between the charger and the member to be charged, a gap is formed between the charger and the member to be charged, making charging difficult. For this reason, in the case of the roller type, countermeasures such as providing a device that can always be cleaned or installing a cleaner on the member to be charged can be considered. However, such measures are difficult in principle with a blade-type charger. Further, it is impossible to completely remove foreign matters such as toner by using only a cleaner such as a polishing roller. The conventional cleaner has only a stance function of reducing a large amount of residual toner and the like. In comparison, the level of foreign matter removal required here is much higher. With respect to the blade type, if even one toner remains, a gap is generated between the blade type charger and the member to be charged, as much as there is toner. Necessary gap control is on the order of several microns, whereas the particle size of the toner is as large as about 10 microns. Therefore, the portion where such residual toner exists cannot be sufficiently charged. The same can be said for the roller type charger. A roller that does not rotate in the same cycle as the member to be charged with respect to the blade type can be expected to have a slight improvement, but not a fundamental improvement. A seventh object is to provide an image forming apparatus using a charger configured to perform sufficient charging even when foreign matter such as toner is present.

Next, in a conventional contact-type charger for charging a photoreceptor by charge injection, even if a pinhole is present in the photoreceptor to be charged, the photoreceptor is uniformly applied to areas other than the pinhole. An eighth object is to provide a structure of a charger capable of giving a proper charging voltage. A ninth object is to provide a method for manufacturing a contact-type charger having the above functions. In addition, a tenth object is to provide an image forming apparatus capable of outputting a good image even when a photoconductor having a pinhole is used.

Further, when the transfer device of the image forming apparatus uses a system for transferring the toner image formed on the image carrier to the transfer member by using a charge providing material, ozone or
The generation of NOx and the generation of wear were problems. Therefore,
By using a charge-imparting material with CNTs (carbon nanotubes) protruding from the surface, it suppresses the generation of ozone and NOx, reduces the burden on the environment, and reduces image deterioration such as transfer dust and image blur. It is an eleventh object to provide an image forming apparatus capable of performing the above. In addition, carbon nanotubes are chemically and mechanically stable, have little fluctuation due to the environment, and have high slidability. Therefore, the charge-imparting material using the carbon nanotube has little wear of the transfer material, particularly wear of the transfer belt and the intermediate transfer belt. The twelfth problem is to suppress the above.

The present invention has been made based on the above-mentioned problems,
Firstly, it is an object of the present invention to provide a charging member that improves charging efficiency in an injection type charger. Second, it is an object of the present invention to provide an image forming apparatus using a member to be charged which improves charging efficiency. Third, it is an object of the present invention to provide an image forming apparatus having a charger capable of applying a uniform charging voltage to a photoconductor in a region other than the pinhole even when a pinhole exists in the photoconductor. I do.

Fourth, it is an object of the present invention to provide a charger manufacturing method capable of manufacturing a charger capable of applying a uniform charging voltage to a photosensitive member in a region other than a pinhole. Fifth
It is another object of the present invention to provide an image forming apparatus that can reduce image deterioration such as transfer dust and image blur while reducing a load on an environment when a transfer device having a charge imparting material is used. Sixth, it is an object of the present invention to provide an image forming method that can reduce image deterioration such as transfer dust and image blur while reducing a load on an environment when a transfer device having a charge imparting material is used.

[0041]

According to a first aspect of the present invention, there is provided a system for performing charging by transferring charge directly or indirectly from the surface of a charger to a surface of a member to be charged. The number of trap levels per area N (1
/ Cm ² ) satisfies the following condition. N> CV / q, where C: capacity per unit area of the member to be charged (1 / cm)
² ), V: desired voltage, q: elementary charge. Where N
Is preferably in a range where a tunnel current can flow from the surface.

As described above, the injection type charging requires a level at which the electrons (holes) are retained, as compared with the conventional discharging charging. On the other hand, the number of necessary trap levels was defined, and a material having more than that was prepared. When the number of trap levels is equal to or more than the required number, charging efficiency is improved.

According to a second aspect of the present invention, in the charged body according to the first aspect, the number n of trap levels per unit volume (acceptor: na, donor: nd) satisfies the following condition. . n <{4πεkT / q ² * log (σ ′ / σ)}
^3. However, σ: desired electric conductivity in the dark of the member to be charged (1 / Ωc
m), σ ': conductivity without trap level, k: Boltzmann constant, T: temperature (K), ε: dielectric constant, n: n
It is assumed that a and nd are smaller (pieces / cm ³ ). here,
The number of trap levels that govern dark decay due to pool Frenkel conduction is specified so that it falls within a desired range.

If there are too many trap levels, a hopping conduction phenomenon occurs between the trap levels. Due to this conduction, the resistance value decreases and the charged state cannot be maintained. Therefore, it is necessary to define the trap level to such an amount that hopping conduction does not matter. Hopping conduction is given by:

Σ = σ′exp (−E1 / kT), E1 =
^{q 2 / (4πεR), R} = 1 / n 1/3 However, sigma: conductivity is dominated by the hopping conduction (1 / Ωcm), σ ' : the conductivity of the absence trap level, k: Boltzmann's constant , T: temperature (K), ε: dielectric constant, R: average distance between traps (cm), n: na, n
The smaller the value of d (number / cm ³ ), the σ may be a desired electrical conductivity in the dark of the member to be charged. By rewriting this equation, n <{4πεkT / q ² * log (σ ′ / σ)}
The formula is ³ . As long as the trap level satisfies this equation, a decrease in resistance due to hopping can be avoided.

According to a third aspect of the present invention, the following conditions are satisfied when the level for trapping electrons is Nd and the level for trapping holes is Na as the trap level of the first aspect. . When V> 0 Na> CV / q When V <0 Nd> CV / q As a result, sufficient charging can be performed for both positive charging and negative charging.

According to a fourth aspect of the present invention, there is provided an image forming apparatus using the object to be charged according to any of the first to third aspects, wherein
It is characterized by using T (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 (MR Farovo).
NATURE 389 (1997) p582). In recent years, the production method can be made very easily, and it has become easier to obtain than other thin wires. Also, since carbon nanotubes are made of carbon alone, compared to thin wires like whiskers made of precious metals,
Environmentally Friendly. 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. Because of these features, many examples have been reported as field emission element members, and they have excellent stability. In addition, it has the properties of graphite used as a solid lubricant and has excellent lubricity, so that it can be effectively used as a charger.

According to a fifth aspect of the present invention, in the image forming apparatus of the fourth aspect, the charger is formed in a blade shape. By using the blade type, the surface of the charger slides on the surface of the member to be charged. As a result, an arbitrary point on the surface of the member to be charged comes into contact with a plurality of regions on the surface of the charger. That is, in the conventional roller, an arbitrary contact point on the charger side contacts only an area having the same size as that point.
On the other hand, by sliding each contact point of the blade type,
The area where any point contacts is greatly expanded. Thereby, even if the contact area and the non-contact area are formed by the surface roughness, the respective areas are alternately replaced by sliding on the surface. That is, uniform charging becomes possible.

According to a sixth aspect of the present invention, in the image forming apparatus of the fourth aspect, the charger is formed in a roller shape. By making the charger a roller type, a portion in contact with the member to be charged and a portion other than the portion are formed, and the two portions are interchanged by rotation. Thus, it is possible to perform cleaning on a portion not in contact with the member to be charged. This cleaning step may be performed with a simple blade-type cleaner, and the effect can be sufficiently exhibited. At the same time, the surface of the charger can be polished by a cleaner. Although the CNT protrudes from the surface of the roller charger, this manufacturing process is performed by the polishing process as described above.
By incorporating this step into the charging process, the charger surface can be constantly polished, a fresh surface can be created, and the CNTs can be constantly projected. This can prevent the CNT from deteriorating due to the operation. Further, by designing the roller to have a sufficient thickness, a long service life can be endured. Also, instead of rotating at the same speed as the member to be charged as in the conventional roller type, the rotation speed is changed and the mutual surfaces are slid, whereby the same effect as the blade type can be obtained. This makes it possible to compensate for the shortage of the contact area, which is a problem in a normal roller charger. Problems such as uneven charging can be eliminated.

According to a seventh aspect of the present invention, in the image forming apparatus according to the fourth aspect, the charger is formed in a brush shape. By using a brush as the surface of the charger, it is possible to prevent the gap from being largely fluctuated due to mixing of toner. In addition, the brush manufacturing method and the like can be diverted. This has a long manufacturing history and is technically proficient compared to a method of simply forming irregularities. By diverting such a method, manufacturing costs can be reduced. In addition, the brush has an application example in a charger and the like, and various conditions such as a material and a shape thereof can be selected based on a track record.

According to an eighth aspect of the present invention, in the image forming apparatus having the charger of the fourth aspect, a resistance layer is provided on a surface facing the member to be charged, and CNTs (carbon nanotubes) are formed on the resistance layer. It is characterized by being held. It has a resistance layer on the surface facing the photoreceptor, and has a structure in which carbon nanotubes are held on the resistance layer. Therefore, if there is a pinhole in the photoreceptor, the contact charger contacts the pinhole with carbon nanotubes. As a result, an overcurrent flows through the carbon nanotube, and the tip of the carbon nanotube generates heat, is oxidized and consumed by oxygen in the air, and is instantaneously separated from the pinhole of the photoconductor. Also, the magnitude of the overcurrent is suppressed by the resistance layer serving as a protection resistor. As a result, the voltage of the DC power supply does not decrease. Therefore, even when there is a pinhole, the photoconductor can be charged uniformly.

According to a ninth aspect of the present invention, in the image forming apparatus having the charger of the fourth aspect, the resistance value of the resistance layer is 10%.
Characterized in that it is a ⁴ to 10 ⁸ Omega. In this case, the same operation and effect as the eighth aspect can be obtained.

According to a tenth aspect of the present invention, in the image forming apparatus having the charger according to the eighth or ninth aspect, the resistance layer is made of a polymer resin in which conductive particles are dispersed. Since the conductive particles are dispersed in the resistive layer made of a polymer resin, the resistance value can be easily controlled by the amount of the conductive particles dispersed and the thickness of the resistive layer.

A method according to an eleventh aspect of the present invention is the method for manufacturing a charger according to the eighth, ninth or tenth aspect, further comprising the step of forming a holding layer made of a polymer resin containing carbon nanotubes on the resistance layer. Polishing the holding layer to project the tip of the carbon nanotube from the holding layer. Since the method of manufacturing the contact type charger includes the step of forming the holding layer and the step of projecting the tip of the carbon nanotube from the holding layer, the process of orienting the carbon nanotube such as electrostatic adsorption or electrophoresis becomes unnecessary. The manufacturing cost of the contact charger can be reduced. In addition, since the carbon nanotube has a structure embedded in the polymer resin of the protective layer, the carbon nanotube is strongly held by the holding layer. As a result, the carbon nanotubes are hardly peeled off from the resistance layer while the contact-type charger slides on the member to be charged, and the long-term stability of the charger is improved.

According to a twelfth aspect of the present invention, in the method for manufacturing a charger according to the eighth or ninth aspect, the resistive layer is made of a metal, alloy, or compound containing at least one of Fe, Co, and Ni. Forming a carbon nanotube by a chemical vapor deposition method using at least one of a hydrocarbon gas such as acetylene, ethylene and methane on the catalyst layer. Features. Forming a catalyst layer made of a metal, alloy, or compound containing at least one of Fe, Co, and Ni on the resistance layer, and forming at least a hydrocarbon such as acetylene, ethylene, or methane on the catalyst layer; Forming carbon nanotubes by chemical vapor deposition using one of the gases. Therefore, the carbon nanotubes can be grown directly from the resistance layer, and the process of separating and purifying the carbon nanotubes becomes unnecessary. As a result, the manufacturing cost of the contact charger can be reduced. Further, since a relatively long carbon tube can be obtained, the number of conductive contacts increases, and the charge injection speed improves.

According to a thirteenth aspect of the present invention, in the image forming apparatus having the charger of the fourth aspect, a carbon nanotube held in the resistive layer, the resistive layer being provided on a surface facing the member to be charged is provided. The tip is protruded from the resistance layer. If the object to be charged has a pinhole, the contact charger contacts the pinhole with carbon nanotubes. As a result, an overcurrent flows through the carbon nanotube, the tip of the carbon nanotube generates heat, is oxidized and consumed by oxygen in the air, and the carbon nanotube is instantaneously separated from the pinhole of the member to be charged. Also, the magnitude of the overcurrent is suppressed by the resistance layer serving as a protection resistor. As a result, the voltage of the DC power supply does not decrease. Therefore, even when there is a pinhole, the member to be charged can be uniformly charged. Further, since the carbon nanotube is embedded in the resistance layer, the carbon nanotube is strongly held in the resistance layer. As a result, the carbon nanotubes are less likely to peel from the resistance layer while the contact charger is sliding on the member to be charged,
The long-term stability of the charger is improved.

According to a fourteenth aspect, in the image forming apparatus having the charger according to the thirteenth aspect, the resistance value of the resistance layer is 10 ⁴ Ω to 10 ⁸ Ω. In this case, the same operation and effect as the invention of claim 13 can be obtained.

The invention of claim 15 is the invention of claim 13 or 1
5. The image forming apparatus having the charger according to 4, wherein the resistance layer is made of a polymer resin in which conductive particles are dispersed. Since conductive particles are dispersed in the resistive layer made of a polymer resin, the number of carbon nanotubes protruding from the surface of the resistive layer and the resistance of the resistive layer can be controlled independently, making it easy to optimize the resistance of the resistive layer .

According to a sixteenth aspect of the present invention, in the method for producing a charger according to the thirteenth, fourteenth, or fifteenth aspect, a step of forming a resistance layer containing the carbon nanotube on a surface opposing a member to be charged; A method for manufacturing a charger, comprising a step of polishing a layer to project a tip of a carbon nanotube from a resistance layer. Forming a resistive layer containing carbon nanotubes on the surface opposite to the photoreceptor; and polishing the resistive layer so that the tips of the carbon nanotubes protrude from the resistive layer. Therefore, the process of aligning and fixing the carbon nanotubes becomes unnecessary, and the cost reduction of the contact type charger is expected.

According to a seventeenth aspect of the present invention, there is provided an image forming apparatus equipped with the charging device according to the eleventh, twelfth or sixteenth aspect. Since the charging device according to claim 11, 12, or 16 is mounted, even when the charging target has a pinhole, charging unevenness does not occur on the charging target, and a good image can be obtained. In the case where the member to be charged is charged by charge injection, ozone or NO
x does not occur. Further, even when the member to be charged is charged by corona discharge, charging can be performed at a lower voltage than that of a conventional contact-type charger, and ozone and NOx can be reduced.

According to an eighteenth aspect of the present invention, an image is formed by transferring a toner image formed on an image carrier made of a member to be charged onto a recording material arranged so as to be close to or in contact with a predetermined transfer nip area. In an image forming apparatus for forming a CNT,
It is characterized in that a charge imparting material having (carbon nanotubes) protruding from the surface is used for a transfer device. By using a charge imparting material having CNTs (carbon nanotubes) protruding from the surface, transfer can be performed at a lower voltage, and ozone and N
Ox is reduced, and deterioration of an image due to “transfer dust” can be reduced. Also, since the coefficient of friction of CNT is small,
Wear of the opposing image carrier and transfer member can be suppressed.

According to a nineteenth aspect of the present invention, a toner image formed on an image carrier made of a member to be charged is transferred to a recording material arranged so as to be close to or in contact with a predetermined transfer nip area. In an image forming method for forming an image, C
It is characterized in that a charge imparting material having NT (carbon nanotubes) protruding from the surface is used for a transfer device. CNT
According to the image forming method using a charge-imparting material in which (carbon nanotubes) protrude from the surface, transfer can be performed at a lower voltage, ozone and NOx can be reduced, and image deterioration due to transfer dust and the like can be reduced. Further, since the coefficient of friction of the CNT is small, abrasion of the image carrier and the transfer member facing each other can be suppressed.

A twentieth aspect of the present invention is characterized in that the charged body of the nineteenth aspect is the charged body of the first, second or third aspect. As described above, by using the charged object for improving the charging efficiency and using the charge imparting material having CNTs (carbon nanotubes) protruded on the surface, transfer can be performed at a lower voltage, and ozone and NOx are reduced. In addition, it is possible to reduce the deterioration of the image due to the transfer dust and the like. Further, since the coefficient of friction of the CNT is small, it is possible to suppress the wear of the image carrier and the transfer member forming the object to be charged.

According to a twenty-first aspect of the present invention, in the image forming apparatus according to the eighteenth aspect, the transfer device is a belt that also serves to convey a recording medium. By using a charge-imparting material having CNTs (carbon nanotubes) protruding from the surface, ozone and NOx are reduced, the surface resistance of the transfer belt is not reduced over time, and image deterioration due to transfer dust and the like can be reduced. In addition, since the friction coefficient of the CNT is small, the wear of the belt can be suppressed, the life of the belt can be extended, and the maintenance of the product is free and the cost is reduced.

According to a twenty-second aspect of the present invention, in the image forming apparatus of the eighteenth aspect, the transfer material or the image bearing member is an intermediate transfer member. The use of a charge-imparting material with carbon nanotubes (CNTs) protruding from the surface reduces ozone and NOx, the surface resistance of the intermediate transfer belt does not decrease over time, and image deterioration due to image blur or transfer dust Can also be reduced. Also, CN
Since the friction coefficient of T is small, the wear of the belt can be suppressed, the service life of the belt can be extended, and the maintenance of the product is free and the cost is reduced.

According to a twenty-third aspect of the present invention, in the image forming apparatus according to the eighteenth aspect, the charge applying material has a blade shape. Carbon nanotube (CNT)
By using a blade-shaped charge imparting material having a protruding surface, transfer can be performed at a low voltage, ozone and NOx can be reduced, and image deterioration due to transfer dust and the like can be reduced. Furthermore, since electric charge can be supplied only to a specific area and electric charge is not applied to the nip entrance, pre-transfer can be suppressed, and image deterioration due to transfer dust can be reduced.

According to a twenty-fourth aspect of the present invention, in the image forming apparatus according to the eighteenth aspect, the charge imparting material has a roller shape. Carbon nanotubes (hereinafter CN)
By using a roller-shaped charge imparting material whose T) protrudes from the surface, transfer can be performed at a low voltage, and ozone and NOx
And the need for additional transporting means such as a transporting belt is eliminated, and image degradation due to transfer dust can be reduced.

According to a twenty-fifth aspect of the present invention, in the image forming apparatus of the eighteenth aspect, the charge applying material has a brush shape. Carbon nanotube (hereinafter CNT)
By using a roller-shaped charge imparting material having a surface protruding from the surface, transfer can be performed at a low voltage, ozone and NOx can be reduced, and deterioration of an image due to transfer dust can be reduced. Also,
Abrasion of opposing parts can be reduced.

[0069]

FIG. 1 is a schematic diagram of an image forming section of an image forming apparatus using an electrophotographic process to which the present invention is applied. The image forming apparatus 1 is a copying machine. The image forming unit 2 includes a photosensitive drum 4 as an image carrier having an outer peripheral surface of a drum-shaped base covered with a charged body (photosensitive body) 3, and a charged body 3. Charger 5 for charging and initializing, an exposure device 6 for forming an electrostatic latent image, a developing device 7 for developing the electrostatic latent image, and a recording material p A transfer device 8 for transferring the recording material p to the recording material p, and a charge removing device 9 for removing the recording material from the photosensitive drum 4 to promote the separation of the recording material, and irradiating the toner remaining on the charged member 3 with light using an LED array. A cleaning device 11 for removing, and a fixing device 1 for fixing a toner image to the recording material p when the separated recording material p is conveyed.
2, etc. The transfer device 8 includes a transfer belt 13 that conveys the recording material p, a charge applying material 14 that supplies transfer charges to the transfer belt, and a power supply 15.

The photosensitive drum 4 is a charged member made of a metal roller 16 and an organic light guide such as OPC, which uniformly covers the surface thereof, or an inorganic photoconductor such as Se or a-Si. (Photoconductor) 3 and a metal roller unit 16
Is grounded. The charger 5 may apply a negative high voltage to the photosensitive drum 4 by a high-voltage power supply, and employs a charging roller or a charging brush. The charged member (photosensitive member) 3 on the peripheral surface of the photosensitive drum 4 is uniformly charged to a negative high potential by the application by the charger 5. The writing head 6 as an exposure device is a laser head or an LED.
A peripheral surface of the photosensitive drum 4 charged to a negative high potential is selectively exposed according to image information. By this exposure, the exposed portion of the negative high potential portion is attenuated to the low potential portion, and an electrostatic latent image is formed.

The developing device 7 includes a developing device 701 containing a non-magnetic toner therein, and the developing device supports a developing roller 702 at a lower opening. The developing roller 702 is connected to a power supply 70
3, the toner is charged to a weak negative potential due to friction and adheres to the surface of the developing roller 702 with a constant layer thickness. The toner is conveyed to the portion facing the photosensitive drum 4 while the developing roller 702 rotates. At a portion where the developing roller 702 and the member to be charged (photosensitive member) 3 on the photosensitive drum 4 are opposed to each other, a potential difference is formed between the low potential portion of the electrostatic latent image and the developing roller 702, and The low potential portion forms a positive potential relative to the developing roller 702. Due to the electric field due to the potential difference, the non-magnetic toner charged to the negative polarity is transferred to the low potential portion of the electrostatic latent image of the positive polarity of the charged body (photoconductor) 3 to form a toner image. The developed toner image is conveyed to the opposing portion between the photoconductor drum 4 and the transfer device 8 by the rotation of the photoconductor drum 4.

A transfer belt 13 is stretched between the photoreceptor drum 4 and the transfer device 8. Transfer belt 13
Are arranged in the form of a flat loop in the horizontal direction.
7, and circulates in a counterclockwise direction indicated by an arrow r in FIG. The conveying belt 17 sandwiches a recording material p fed from a paper feeding unit (not shown) between a driven roller 19 and an auxiliary roller 21 which presses the recording material via the transfer belt 13, and transfers the recording material to a photosensitive member. It is transported so as to come into contact with the drum 4. The charge providing material 14 of the transfer device 8 contacts the inside of the upper circulating portion of the transfer belt 13 and the photosensitive drum 4
Are arranged so as to sandwich the transfer belt 13 at a position opposed to. The charge applying material 14 applies a positive charge to the transfer belt 13, and the charge is applied to the recording material by the dielectric effect of the transfer belt 13. Due to the electric field generated by the electric charges, the negative toner image on the photosensitive drum is transferred to the recording material p in contact with the photosensitive drum.

The recording material p to which the toner image has been transferred is conveyed to the left in the figure by the transfer belt 13 and the toner image is heat-fixed in the fixing device 12 and discharged to a tray (not shown). Hereinafter, each embodiment of the charged member 3 on the photosensitive drum 4 which is a main member of the image forming apparatus 1 of FIG.
[1], [2], and [3] will be described in this order.

[1] The member to be charged 3 will be described. The number of trap levels of the member to be charged 3 greatly differs depending on the material to be charged or the method of forming the same. Good examples include semiconductor materials such as Si and GaAs.
It is known that, for example, when GaAs is formed by a liquid growth pulling method, a large amount of a deep level called EL2 enters the center of the band gap. It is known that this does not occur very much in vapor phase growth. This E
L2 is effectively utilized when forming semi-insulating GaAs. In the first embodiment shown in FIG. 1, the member to be charged 3 is constituted as an inorganic photosensitive member, and a-Si (amorphous silicon) is employed.

Since a-Si is a semiconductor and exhibits photoconductivity, it has been actively studied as a photoreceptor for electrophotography, and has been used in actual machines. In the case where the trap level is handled as in the present invention, the control is relatively easily performed, and there are many findings such as an evaluation method thereof, and the handling is easy. Usually, a-Si is formed by a sputtering method. At this time, Si is used as a target, and Ar is used as a gas. A-Si formed by sputtering only with Ar contains many trap levels (dangling bonds). When sputtering is performed, H is mixed into Ar by mixing H ₂ with Ar. The H causes passivation inside the a-Si and plays a role of reducing the number of trap levels. That is, the mixing amount of H ₂ in deposition sputtering, can control the number of trap levels. Usually, when H is not included, there are a large number of trap levels, and the number of trap levels is 10 ²⁰ / c.
m is about ^3, whereas, by performing the passivation by H, the level is known to be reduced to ^{1 * 10} 15 / cm ^3. Regarding the surface state, a method of passivating the surface state has been developed by the Si semiconductor technology. By using that method, the surface state can also be reduced.

In a-Si: H, there is also a problem that the band gap is too narrow to increase the resistance and the wavelength sensitivity. Therefore, as in the previous _{H 2, CO 2, O 2} ,
There is a method of mixing N ₂ , NO _{2 and the} like. This gives a
-Si contains O and C, a-Si: O: H and a-S
i: C: H. At this time, the band gap becomes large due to the entry of C and O. This control can also be performed based on the mixing amount. When the band gap is widened, the energy level of the trap level is increased, and pool Frenkel conduction and the like can be reduced. Pool Frenkel conduction plays an important role in handling high voltages such as electrophotography processes, and it is necessary to avoid low resistance due to this. For this reason, put C, O, etc.
Increase resistance.

The band gap can be measured by optical measurement, and the trap level was quantified by the following method.

Here, the “method of evaluating the number of trap levels” will be described. The above trap levels include many surface states. For this reason, the conventional DLTS (Deep L
evel Transient Spectrosco
py) or the like and a method of measuring by vapor deposition of a metal cannot be adopted. Therefore, in the present embodiment, a method was devised in which the trap level including the surface level can be quantified. As a method of quantifying the surface state, a tunnel current used in an STM (scanning tunnel microscope) or the like was used.
The tunnel current does not flow unless there is a level on the surface of the evaluation material. In addition, the electric charge accumulates at the point where the electric current flows, and when the electric charge is made, it becomes impossible to flow the electric current beyond the electric charge. That is, no current flows when the level is buried. From this, the level on the surface can be quantified. In this evaluation, since the STM was used, a large area could not be quantified, but was averaged from a small area. The applied voltage was the trap level at that voltage in accordance with the applied voltage in the examples and comparative examples.

Here, "calculation of trap level regulation formula (1) of claim 1" will be described. Number of charges per unit area required for charging (N = Q / q) (number of trap levels)
Is set to about 4.3 * 10 ¹¹ / cm ² . Here, when C and V are assumed to be the following conditions, Q = CV = 7/10 ⁸ C (1) C = 140 pF / cm ² , V = 500 V, q = 1.
6/10 ¹⁹ C Thickness of charged body: 50 μ, Dielectric constant: 8 * 8.8 / 10 ¹²
(F / m). Thereby, it can be determined whether the condition of claim 1 is satisfied, that is, whether the charging efficiency can be maintained satisfactorily.

Next, the "calculation of the trap level regulation formula (2) of claim 2" will be described. Number of trap levels N
If there is too much, hopping conduction phenomenon between trap levels occurs. Due to this conduction, the resistance value decreases and the charged state cannot be maintained.

Therefore, it is necessary to define the trap level in such an amount that hopping conduction does not matter.
Hopping conduction is given by: σ = σ ′ exp (−E1 / kT) E1 = q ² / (4πεR), R = 1 / n ^1/3 where σ: conductivity (1 / Ωcm) governed by hopping conduction, σ ′: trap Conductivity without level, k: Boltzmann constant, T: temperature (K), ε: dielectric constant, R: average distance between traps (cm), n: na, n
The smaller the value of d (number / cm ³ ), the σ may be a desired electrical conductivity in the dark of the member to be charged. By rewriting this equation, the following equation is obtained: n <｛4πεkT / q ² * log (σ ′ / σ)｝ ³ ··· (2) Here, the number n of trap levels per unit volume (acceptor: na, donor: nd) (density)
If this satisfies this condition, a decrease in resistance value due to hopping can be avoided. Here, the number n of trap levels per unit volume that governs dark decay due to Poole-Frenkel conduction is defined so as to fall within a desired range.

Next, an a-Si member to be charged having characteristics capable of maintaining good charging efficiency was manufactured as "Example 1 of member to be charged". The substrate used was an aluminum element can. Here, the number N of trap levels is 10 ¹³ (1 / cm ² ), and the volume resistance is 1
At ¹³ Ωcm, a decrease in resistance was suppressed.

Ga was used in the charger 5 in a boat. Ga is a metal having high conductivity, and is a liquid at normal temperature, and therefore has high adhesion to the member 3 to be charged. For these reasons, they are frequently used as charging electrodes. The boat is made of a resin, and an Al film is formed inside the boat to have conductivity. Al and Ga are ohmic,
Voltage is applied to Ga. The charger 5 and the charged object 3
Are arranged as shown in FIG. 1 and a voltage is applied. Thus, the charged potential on the surface of the member to be charged is evaluated by a surface voltmeter. <Evaluation method> Temperature / humidity: 20 ° C, 50% Rotation speed: 200 mm / sec Applied voltage: −500 V Measure the surface potential, and record the average value. <Result> -480V with respect to -500V (V <0) application
(See Table 1), and a sufficient necessary potential could be obtained. Next, a comparative example with respect to the “Example 1 of the member to be charged” will be described.

Comparative Example 1 An a-Si member to be charged was formed in the same manner as in "Example 1 of member to be charged". In this case, the charger and the evaluation method were all the same as in Example 1. Here, the number of trap levels was 10 ¹³ / cm ^{2, the} film thickness was 10 μm, and the resistance value was 10 ¹³ Ωcm.

Comparative Example 2 An a-Si member to be charged was formed in the same manner as in "Example 1 of member to be charged". In this case, the charger and the evaluation method were all the same as in Example 1. Here, the number of trap levels was 10 ¹³ / cm ^{2, the} film thickness was 20 microns, and the resistance value was 10 ¹³ Ωcm.

Comparative Example 3 An a-Si member to be charged was formed in the same manner as in "Example 1 of member to be charged". In this case, the charger and the evaluation method were all the same as in Example 1. Here, the number of trap levels was 10 ¹³ / cm ^{2, the} film thickness was 30 μm, and the resistance value was 10 ¹³ Ωcm.

Comparative Example 4 An a-Si charged body was formed in the same manner as in "Example 1 of a charged body". In this case, the charger and the evaluation method were all the same as in Example 1. Here, the number of trap levels is 10 ¹³ / cm ^{2, the} film thickness is 0.1 μm, and the resistance value is 10 ¹³ Ωcm. In this case, when the film thickness is 0.1 μm, the number of trap orders required for charging is determined. N is 8.3 * 10
¹³ / cm ² , which did not satisfy claim 1.

Comparative Example 5 An a-Si charged body was formed in the same manner as in "Example 1 of a charged body". In this case, the charger and the evaluation method were all the same as in Example 1. Here, the number of trap levels is 10 ¹³ / cm ^{2, the} film thickness is 0.01 μm, and the resistance value is 10 ¹³ Ωcm. In this case, when the film thickness is 0.01 μm, the number of trap orders required for charging is determined. N is 8.3 * 10
¹³ / cm ² , which did not satisfy claim 1.

Comparative Example 6 An a-Si charged body was formed in the same manner as in "Example 1 of a charged body". In this case, the charger and the evaluation method were all the same as in Example 1. Here, the number of trap levels is 10 ¹⁰ / cm ^{2, the} film thickness is 50 microns, and the resistance value is 10 ¹⁵ Ωcm, and the number N of trap orders required for charging is 4.3 * 1.
0 ¹³ / cm ² , which did not satisfy Claim 1.

Comparative Example 7 An a-Si member to be charged was formed in the same manner as in "Example 1 of member to be charged". In this case, the charger and the evaluation method were all the same as in Example 1. Here, the number of trap levels is 10 ¹¹ / cm ^{2, the} film thickness is 50 microns, and the resistance value is 10 ¹⁴ Ωcm, and the number N of trap orders required for charging is 4.3 * 1.
0 ¹³ / cm ² , which did not satisfy Claim 1.

Comparative Example 8 An a-Si member to be charged was formed in the same manner as in "Example 1 of member to be charged". In this case, the charger and the evaluation method were all the same as in Example 1. Here, the number of trap levels was 10 ¹⁴ / cm ^{2, the} film thickness was 50 μm, and the resistance value was 10 ¹¹ Ωcm.

Comparative Example 9 An a-Si member to be charged was formed in the same manner as in "Example 1 of member to be charged". In this case, the charger and the evaluation method were all the same as in Example 1. Here, the number of trap levels is 10 ¹⁵ / cm ^{2, the} film thickness is 50 microns, and the resistance value is 10 ¹⁰ Ωcm. The number of trap levels increases, hopping conduction increases, and the resistance value decreases relatively. However, this does not depart from the provisions of claim 2.

Comparative Example 10 An a-Si member to be charged was formed in the same manner as in "Example 1 of member to be charged". In this case, the charger and the evaluation method were all the same as in Example 1. Here, the number of trap levels is 10 ¹⁷ / cm ^{2, the} film thickness is 50 microns, and the resistance value is 10 ⁹ Ωcm. Here, the number of trap levels per unit volume increases (Table 1 shows the values per As shown, the value per unit volume also increases), the hopping conduction increases, and the resistance value decreases. This deviates from the provisions of claim 2 (the trap level regulation formula of claim 2).

Comparative Example 11 An a-Si member to be charged was formed in the same manner as in "Example 1 of member to be charged". In this case, the charger and the evaluation method were all the same as in Example 1. Here, the number of trap levels is 10 ¹⁸ / cm ^{3, the} film thickness is 50 microns, and the resistance value is 10 ⁸ Ωcm. Here, the number of trap levels per unit volume increases (Table 1 shows the values per As shown, the value per unit volume also increases), hopping conduction increases, and resistance decreases. This deviates from the provisions of claim 2 (the trap level regulation formula of claim 2).

Comparative Example 12 An a-Si member to be charged was formed in the same manner as in "Example 1 of member to be charged". In this case, the charger and the evaluation method were all the same as in Example 1. Here, the number of trap levels is 10 ¹³ / cm ^{2, the} film thickness is 50 μm, and the resistance value is 10 ¹³ Ωcm. However, in this comparative example, the applied voltage was +500 V
(V> 0). +50 in trap level measurement
0 V was applied.

Comparative Example 13 An a-Si member to be charged was formed in the same manner as in "Example 1 of member to be charged". In this case, the charger and the evaluation method were all the same as in Example 1. Here, the number of trap levels is 10 ¹¹ / cm ^{2, the} film thickness is 50 μm, and the resistance value is 10 ¹³ Ωcm. However, in this comparative example, the applied voltage was +500 V
(V> 0). +50 in trap level measurement
0 V was applied. Claim 1 was not satisfied.

Comparative Example 14 An a-Si member to be charged was formed in the same manner as in "Example 1 of member to be charged". In this case, the charger and the evaluation method were all the same as in Example 1. Here, the number of trap levels is 10 ¹⁰ / cm ^{2, the} film thickness is 50 μm, and the resistance value is 10 ¹³ Ωcm. However, in this comparative example, the applied voltage was +500 V
(V> 0). +50 in trap level measurement
0 V was applied. Claim 1 was not satisfied.

[0098]

[Table 1]

In Example 1 of the member 3 to be charged, an inorganic material was selected from the viewpoint of controlling the number of trap levels, and an experiment such as a comparative example was performed. In "Example 2 of Charged Member", application to a polymer material was considered in consideration of application to an organic photosensitive member. There is no major phenomenological difference between the polymer material and the inorganic material with respect to the charging phenomenon. However, there is a possibility that the polymer material has more trap levels, particularly surface levels. Therefore, the following comparative experiment was performed in consideration of the surface state. It has been proved that the results of claim 1 also apply to polymers. As a method of the experiment, the capacitance component of the charged body 3 is controlled by controlling the thickness of the charged body 3. This indicates that the provisions of claim 1 are necessary.

In "Example 2 of the member to be charged", PC (polycarbonate) was used. The PC film was formed by applying a PC dissolved in a solvent to a metal surface and drying and curing the PC.
The film thickness was controlled by a film forming method. The experiment was performed on the assumption that the number n of the trap levels is almost the same if the material is the same. When performing this example, the number of trap levels of the PC was measured. Incidentally, the number of trap levels in the PC obtained by the above evaluation method is about 1.7 * 10 < ¹⁴ > / cm < ² >.

Here, the trap level expression of claim 1
(1) will be described. Per unit area required for charging
The number of charges (N = Q / q) is 8 * 10¹¹/ Cm ² About
Set the degree. However, when C and V are set as follows, Q = CV = 1.3 / 10⁷C: C = 260 pF / cm
², V = 500V, q = 1.6 / 10¹⁹C Thickness of charged body: 10 μm, dielectric constant ε: 3 * 8.8 / 10
¹²(F / m), area S: 1/10⁴m²And this
It is possible to judge whether or not the condition of claim 1 is satisfied.
You.

The evaluation system is as described in "Example 1 of Charged Body (Inorganic)", and is omitted here. Comparative Example 2-1 The film thickness of “Example 2 of a member to be charged (organic)” was changed. This changes C from C = εS / d. d was 1 micron. In this comparative example, the applied voltage was set to +500 V (V> 0). The number of trap levels required was 8 * 10 ¹² / cm ² . Comparative Example 2-2 The film thickness of the member to be charged (organic) in “Example 2 of member to be charged” is 0.1 μm. In this comparative example, the applied voltage is +5
The test was performed at 00 V (V> 0). The number of trap levels required was 8 * 10 < ¹³ > / cm < ² >. Comparative Example 2-3 The film thickness of the member to be charged (organic) in “Example 2 of member to be charged” was 10 nm. In this comparative example, the applied voltage is +500 V
(V> 0). The number of trap levels required is 8
* 10 ¹⁴ / cm ² , the number of trap levels increases, hopping conduction increases, and the resistance value decreases. This does not satisfy claim 2.

[0103]

[Table 2]

Next, the cross-sectional structure of the charged body 3 in the "charged body (organic) embodiment 2" will be described. As shown in FIG. 5, the organic photoreceptor is formed from the surface to a surface protective layer A1,
It comprises a charge generation layer A2, a charge transport layer A3, an undercoat layer A4, and a substrate A5. This will be described below in order.

Surface Protective Layer A1 The surface protective layer A1 is transparent and has high mechanical strength. As the material, commercially available resins such as polyester, polycarbonate, polyurethane, acrylic, epoxy, silicone, alkyd, and vinyl chloride-vinyl acetate copolymer can be used. In this example, polycarbonate used as a binder in the charge generation layer and the charge transport layer was used. Polycarbonate has a skeleton similar to PET shown in Example 2 and is similar in charging characteristics. This is because the distribution states of the trap levels referred to in the above description are similar. Further, the evaluation of the trap level described later has obtained the results satisfying claims 1, 2 and 3. In addition, as a result of a study for improving the strength and the dispersibility, the use of a surface layer formed by coating this on the photosensitive layer of the photoreceptor greatly improved the film strength.

Charge Generation Layer A2 The charge generation layer A2 used was of a long wavelength (780 nm) conventionally used for digital. Examples of the CGM include a squarylium dye, a metal-free phthalocyanine type, a metal phthalocyanine type, an azulenium salt color, a thiapyrylium salt, a polycyclic quinone type, a perylene type, an azo pigment type, and an azo pigment. These were put into a binder material such as polyvinyl butyral resin. These were put into a binder material such as polyvinyl butyral resin. The film thickness was about 1 to 10 microns, and was formed by spray coating.

Charge Transporting Layer A3 For the charge transporting layer A3 of this example, a conventionally used material for hole transport was used. Examples of the charge transport agent include oxadiazole derivatives, pyrazoline derivatives, hydrazone derivatives, triphenylmethane derivatives, oxazole derivatives, triarylamine derivatives, diphenylmethane derivatives, stilbene derivatives, butadiene derivatives, polyvinylcarbazole, and polysilane derivatives. As the binder, a polycarbonate resin or a polyester resin was used. The concentration of the transfer agent was about 50%. The film thickness is 2
It was formed by dipping coating at about 0 microns.

Undercoat Layer A4 The purpose of the undercoat layer A4 is to improve the chargeability of the photoreceptor and to improve the adhesiveness and coatability of the photosensitive layer to the substrate. As the material used, for example, in a single-layer configuration, polyethylene, polystyrene, acrylic resin, vinyl chloride resin, vinyl acetate resin, polyurethane, epoxy resin, polyester, melanin resin, silicone resin, polyvinyl butyral, resin such as polyimide, or a resin thereof And copolymers. In addition, casein, gelatin, polyvinyl alcohol, ethyl cellulose and the like are also used. Further, a film in which conductive particles realized by a metal such as Ag, Cu, Ni, Au, and Bi or carbon are dispersed in an adhesive is also effective. A layer containing titanium oxide surface-treated with tin oxide or alumina is also effective. Also, titanium oxide fine particles coated with alumina, titanium oxide surface-treated with a titanate-based coupling agent, a layer in which metal oxide particles surface-treated with a silane compound or a fluorine-containing silane compound are dispersed in an adhesive, etc. Is used.

Substrate A5 The substrate A5 preferably has characteristics such as conductivity, high mechanical strength, low production cost, and good film adhesion.
Therefore, a general metal is used, for example, Al, SU
Examples include S, Fe, Ni, Cu, Mg, and Ag. In this case, Al was used. Alternatively, a metal film can be formed on an insulating material such as acrylic to be used as a substitute.

[2] Regarding the charger 5, the embodiments [2-A] to [2-H] will be described in order. [2-A] Example 1 of Charger The roller charger 5a as “Example 1 of the charger” is a roller type as shown in FIGS. 2 and 3, and is a copying machine 1a as an image forming apparatus. And has a function of applying a voltage to the member to be charged. Adopt a laminated configuration. The base of the roller charger 5a will be described.

The conductive substrate which is the cylindrical substrate 20 is made of Al, S
US, Fe and other metal conductors or acrylic resin,
It is preferable that a conductor film is formed on the surface of a plastic insulator. If the volume resistance is 1/10 ² Ωcm or less, resins and rubbers containing various conductive agents can be used. This time, aluminum was adopted because of the manufacturing costs of the manufacturing process. After processing aluminum into a cylindrical shape having a thickness of 2 mm and a diameter of 20 mm, the surface is roughened to the order of 0.1 mm with a grinder so as to improve adhesion. Figure 3 on this
, A conductive elastic body 21 having a thickness of 5 mm is attached.

The base resin will be described. Conductive elastic body 21
Is obtained by dispersing conductive particles in a base material having elasticity. Various thermoplastic elastomers such as polyester-based elastomer, polyamide-based elastomer, polyurethane-based elastomer, soft vinyl chloride resin, styrene-butadiene-styrene block copolymer elastomer, and acrylic elastomer are suitable for the base material. 6, polyamides such as nylon 6,6, nylon 6-nylon 6,6 copolymer, nylon 6,6-nylon 6,10 copolymer, and alkoxymethylated nylon such as methoxymethylated nylon; Modified products, silicone resins, acetal resins such as polyvinyl butyral, polyvinyl acetate, ethylene-vinyl acetate copolymers, ionomers and the like can also be used. Examples of the rubber include natural rubber, butadiene rubber, styrene rubber, butadiene-styrene rubber, nitrile-butadiene rubber, ethylene-propylene copolymer rubber, ethylene-propylene-nonconjugated diene copolymer rubber, chloroprene rubber, butyl rubber, and silicone rubber. , Urethane rubber, acrylic rubber and the like are preferable. This time, we adopted silicone resin. As dispersed conductive particles, conductive carbon black,
Metal powders such as silver, gold, copper, brass, nickel, aluminum, and stainless steel, and powdered conductive agents such as tin oxide-based conductive agents can be used. In addition, nonionic, anionic, and cationic types can be used. Alternatively, an amphoteric or other organic conductive agent or an organic tin-based conductive agent can be used. Further, in order to effectively perform uniform dispersion of the conductive agent, it is also possible to partially use an acid-modified resin or rubber obtained by copolymerizing an ethylenically unsaturated carboxylic acid such as acrylic acid, methacrylic acid, and maleic anhydride. It is valid. The conductive elastic body 21 of FIG. 3 employs carbon black as conductive particles.

This carbon black is dispersed in a heat-melted silicone resin of a base material.
By cooling, a solid having a desired shape can be obtained.
The conductivity of the material thus obtained can be appropriately adjusted depending on the material ratio. This time, the resistance was adjusted to about 10Ωcm. The surface resin that covers the surface of the conductive elastic body 21 formed as described above will be described.

As the surface resin, a single layer 22 of medium resistance containing CNTs (carbon nanotubes) is formed to form a projection on the surface. As the medium-resistance film provided on the conductive elastic body, a resin or rubber adjusted to have an appropriate resistance value by the combination of the conductive agent and the layer thickness is used. The types of the resin and rubber may be the same as those described above, but in addition to these, a fluorine-based resin or rubber such as polyvinylidene fluoride (PVDF),
Polytetrafluoroethylene (PTFE), tetrafluoroethylene-hexafluoropropylene copolymer (P
TFE / HFP), perfluoroalkoxy-based fluororesins and the like are preferably used. In particular, when these fluorine-based resins and rubbers are used, they are inactive and have a small coefficient of friction, so that there is a great merit in terms of the life of the charged member (photosensitive member) 3 and the charging roller 5a. This time, PVDF was adopted.
The mechanical strength of PVDF is adjusted so as to be smaller than that of the member to be charged. Note that the resistance value of the medium resistance layer 22 is 1 × 1
0 to 1 × ^{10 10} Ωcm, especially 1 × 10 ^{6 to} 1 × 10 ⁷ Ω
cm. This resin contains CNT. Since this CNT also acts as a filler, the resistance was controlled by the CNT and carbon black. A desired resistance value was obtained at a CNT concentration of about 10 wt% and carbon black of about 5 wt%.

This resistance control is based on a calculation as a measure against pinholes as follows. <Calculation> Ratio of pinhole area to charged area = 1: 10
⁵ (however, the pinhole area is 100 μm ² , the charging area is 2 *
300 mm) (that is, “Rb ′ = Rb
* 10 ⁵ ". 10) If you want to reduce the effects of short circuits by 10%,
* (Rb + Rc + Ropc) = Rb ′. By substituting “Rb ′ = Rb * 10 ⁵ ”, Rb + Rc + Ro
pc = Rb * 10 ⁴ Ropc = Rb * 10 ⁴ OPC volume resistivity 10 ¹² Ωcm (dark resistance), thickness 50
Rb = 5 * 10 < ⁶ > [Omega] cm (approximately 1 mm in thickness) In addition, other embodiments of the charger that take measures against the pinhole will be described later as embodiments 4 to 6 of the charger.

The characteristics required for the surface member (surface resin covering the surface of the conductive elastic body) will be described. Fine protrusions were used as the surface agent in this example. The microprojection refers to an extremely thin line firmly fixed by the surface of or inside the base resin. The aim is to improve the contact probability by these minute projections. The microprojections directly transfer or receive electric charges to or from the charged member (photosensitive member) 3 when charging is performed. It is thought that the transfer of the main charge is in contact and the charge is injected. Therefore, it is desired that the contact be made as frequently as possible. It is also believed that non-contact field emission is occurring at the same time. In this case, it is desired that the minute projection and the member to be charged face each other at a distance as short as possible. As a result, charges can be efficiently sent to the member to be charged.

Since the minute projections may come into direct contact with the member to be charged 3, a material having as little friction as possible is desired. In the case of a normal contact charger, the surface is processed with a material softer than the member to be charged 3 so that the member to be charged is not damaged as much as possible. The surface of an organic charging member often used in actual machines is particularly soft, and such consideration is important. In particular, in recent years, photoreceptor layers for achieving higher definition have been made thinner. At present, the thickness is about several tens of microns, but it is inevitable that the thickness will be several microns in the future. In addition, the thickness that can be cut by the current cleaning blade is also said to be several microns, and it is necessary to change such a function in the future. In addition, the market demands a longer life of the photoconductor, and a demand for a function of reducing damage to the photoconductor by the charger has been increased.

In order to prevent the photosensitive member (charged member) 3 (see FIG. 5) from being damaged as described above, it is necessary to provide lubrication to the charger 5a side. Many ordinary lubricants are liquids such as oils, and the photoreceptor 3 is well known for a fixing process using silicone oil or the like. In this process, it is not impossible to use a liquid material such as oil between the charger and the photoconductor. However, image deletion, charging failure, exposure failure, transfer failure, and the like caused by the oil remaining on the photoconductor side are considered. Therefore,
In the present invention, the charger is provided with solid lubricity. As this solid lubricant, graphite, MoS2,
A layered effect such as Teflon (registered trademark) may be used. Although it is hard to say that the layered lubricating mechanism has been completely clarified, even such a layered effect has no adverse effect on the photoreceptor. Since the minute projections also directly touch the member 3 to be charged, a material having lubricity is desired.

CNTs (carbon nanotubes) are expected to have lubricity like graphite. In previous reports, although it is theoretical calculation, there is also a report that sliding friction is smaller than rolling friction due to phenomena that occur on the nano order. For solid lubricants used in this charger,
We cannot use the rolling phenomenon. In other words, sliding friction cannot be avoided, but in this way,
The possibility that such lubricity can be enhanced by making the fine projections thinner is shown. In other words, it is shown that making the fine projections thin not only increases the contact area but also reduces the friction coefficient.

[0120] The minute projections need to have conductivity for flowing electric charges when charged. Although the total resistance value of the charger also appears in the above equation, a smaller value is preferable from the viewpoint of improving the charging ability. Also, as a countermeasure against pinholes, it is necessary to increase the resistance value on the charger side. As described above, it is more desirable to control the micro projections on the side close to the member to be charged. However, this time, this control was carried out with a fixing resin, and the microprojections were designed to minimize the resistance. In field emission,
It is desirable that the tip is as sharp as possible and the work function of the surface is small as the minute projection. Further, since the present invention is used in the atmosphere, an increase in work function due to an oxide film or the like poses a serious problem. For example, it is known that a metal oxide such as Al, which has a low resistance value and is inexpensive, is usually formed on the outermost surface.

As mentioned earlier, thinner is better, but there is a possibility that there is a trade-off between the demand for fineness and the demand for strength. In this connection, it is very important to find a material having both sufficient thinness and strength. As a material constituting the microprojections, a necessary factor is a manufacturing cost. Although some ultrafine materials are considered at the research level, few materials have actually reached the production level 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 the fine projections include (a) fineness (nano order), (b) conductivity, (c) friction resistance (mechanical strength), and (d) flexibility. sex,
A material having both (e) chemical stability, (f) cost, and (g) lubricity is required. Various materials such as metal whiskers, WS2 nanotubes, and CB nanotubes can be considered as materials satisfying some of these conditions. However, it is considered that CNT is well balanced in all aspects and has such characteristics.

Here, CNT (carbon nanotube) used for the charger 5a will be described. In general, resin, rubber, or the like is used for the surface member of the charger 5a because of its superior processing. Since such an advantage is also required in the present invention, such a member is desired. Further, it is desired that the minute projections have resistance to mechanical friction such as contact with the member to be charged 3. From such a demand, it is optimal to use CNT (carbon nanotube).

As its name suggests, CNT is known to have a nano-order diameter and a micron-order length, and was recently discovered in 1991 by Sumio Iijima of the NEC Research Laboratory. The material is made of 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, and an open end 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 it has become a familiar material. is there.

Research on basic physical properties has also been made vigorously since the discovery since its discovery of its unique shape. In particular, it was expected from first-principles calculations that its electrical properties were metallic or semiconductive. . In addition, various things have been found in spite of its small size and difficult evaluation, such as its extremely high mechanical strength and its ability to 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, they are appropriately dispersed in an epoxy resin or the like, and have very high adhesion at the interface, so that they can be fixed firmly. For this reason, handling, etc., has become easy, for example, by embedding in a resin although it is nano-sized. In addition, since the material is close to graphite, it has a potential as a solid lubricant. In addition, some previous reports indicate that the friction coefficient on the nano order is smaller for sliding friction than for rolling friction. Although many reports have not yet been made on the lubricity of carbon nanotubes, their potential as lubricants is expected to be high.

On the application side, a high non-uniform electric field can be generated due to the size of the aspect and the 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 and a gas adsorbing substance. Examples of using mechanical strength include dispersing the resin in a resin to strengthen the resin (O. Lou
rie A. P. L. 73 (1998) 3527), a report on application to actuators in the micro world (Ray)
H. Baughman SCIENCE 284
(1999) 1340).

As described above, the carbon nanotube almost satisfies the requirements for the above-described microprojections.
The present invention considers this material to be optimal. However, not all of the above requirements have to be satisfied in the present invention. If applicable.

[0128] The CNT manufacturing method will be described. CN
The following method can be considered as a method for manufacturing a charger using T. (A) Resin dispersion type (b) Electrophoretic flocking type (c) Surface growth type by CVD
Details are described in Examples of 347478.

It has been described above that CNTs can be synthesized by an arc discharge method, a CVD method, or the like. This time, the one formed by the arc discharge method was used (manufactured by Bukky-USA).
This is crushed appropriately in a mortar or the like, and mixed with the nylon solution as the brush material. At this time, the resistance value of nylon is controlled by doping. The CNTs were mixed so that the concentration became about 10 wt%. This is controlled by a trade-off between the protrusion density and the strength of the nylon brush. The nylon resin mixed in this way is formed into fibers by a jetting method. At this time, the diameter of the nylon fiber is 15
It was controlled to about a micron. After that, it is brushed with a pile. Each brush is fixed by a fixing cloth. The density at this time was 120 lines / mm ² . The length is about 2 mm. In this state, the brush is exposed to oxygen plasma. The oxygen plasma oxidizes the nylon resin. Although the CNTs are slightly oxidized, the CNTs can be selectively etched because of their greatly different rates. This plasma exposure is performed for about 30 minutes, and the brush diameter is reduced from 15 microns to about 10 microns. At this time, the CNTs are exposed as minute projections from the brush surface. This density is about 1 wire / μm ² . The protrusion length is about 1 μm (micron). Thereafter, the brush cloth is fixed to the substrate to complete the brush cloth.

The cleaner for performing the polishing step of the roller charger 5a will be described. As shown by a two-dot chain line in FIG. 2, the role of the cleaner 19 installed in the roller charger 5a is to constantly polish the surface of the roller charger 5a, maintain the surface at an appropriate roughness, and to obtain fresh CNT from the surface. Is to protrude. Therefore, the above-mentioned polishing step can be performed by the cleaner 19. As the cleaner 19, a member having high mechanical strength and capable of always maintaining an appropriate projection state is used.
Metals or alloys such as Al, SUS, Fe, etc., resins having high mechanical strength such as acryl and epoxy, and inorganic substances such as silica, glass and other oxides are suitable for the use. This time, SUS was used. The cleaner 19 is also in the form of a roller, and can be removed when the resin of the charger adheres to the SUS surface. The surface of SUS has roughness on the order of microns, and this SU
S contacts the roller charger 5a at a different rotation speed to polish the roller surface of the charger. By adjusting the pressing pressure, the shaving amount can be controlled, and since the thickness of the roller is about 1 mm, the roller is adjusted to about 1 nm / rotation in order to have a life of about 500 * 10 ³ sheets. .

The driving method of the roller charger 5a will be described. The operation method is based on the ordinary roller charger 5a. The voltage was DC and the applied voltage was 300V. Claim 2 satisfies this value. Therefore, normal discharge does not occur, and generation of ozone can be prevented. This can be checked with an ozone detector or the like. The rotation speed of the photoreceptor was designed to be compatible with 60 cpm. In this embodiment, satisfactory charging ability was obtained even at this speed. [2-B] Second Embodiment of Charger The charger 5a (Example 1) of the copying machine 1a shown in FIG. 2 was a roller charger 5a. A format may be adopted. The blade-shaped blade charger 5b of FIG. 6 is employed in place of the charger 5a of the copying machine 1a of FIG. FIGS. 12A and 12B
As shown in (2), the contact area s2 can be increased by sliding on the surface as compared with the contact area s1 of the roller charger 5a. Outside the blade-shaped portion, the roller charger 5 of FIG.
It has almost the same configuration as described in a, and each member may be the same. The nip np is designed to be 2 mm, and the resistance value,
The thickness, surface roughness, and the like are the same as those of the roller charger 5a in FIG. As with the roller charger 5a, the surface of the blade has CN
It processed so that T might protrude.

[2-C] Third Embodiment of Charger Although the charger of FIG. 2 is the roller charger 5a, a brush type may be adopted as “third embodiment of the charger” instead. . The basic structure of the brush type charger 5c is shown in FIGS.
Shown in The brush-type charger 5c is a base 2 for fixing a brush.
2, brush 23 and CN fixed to the brush
T24 (see FIG. 8). Since each part is a common element required for other chargers, these elements will be described first.

The base 22 of the brush type charger 5c will be described. The function of the base 22 is to conduct the electric current with conductivity and to fix the brush uniformly and hardly. In addition, a certain pressure is applied between the base and the member to be charged 3, whereby the brush 23 bends with its elasticity at a portion in contact with the member to be charged 3, and a predetermined pressure is applied. Like that. This pressure also needs to be uniform in the longitudinal direction of the member to be charged. Since the base is supported at the two end points in the longitudinal direction, the base 22 is pressed so that the pressing pressure at the supported point and at a position distant therefrom does not change significantly.
Some mechanical strength of itself is required.

As shown in FIG. 8, since the substrate 22 needs to have conductivity and strength, the resin layer 221 has a structure in which the mechanical strength and the conductivity of the fixed layer 222 are separated from the function. The reason why the resin was selected was that it was determined that there was a merit from the viewpoint of recycling, because it was possible to obtain appropriate strength, to be lightweight and inexpensive, to be used for the casing of the copying machine 1 and the like. From such a viewpoint, it is preferable to use the same resin material as that of the housing of the copier, for example, from the viewpoint of ease of recycling such as PC and ABS. The shape was devised from the required strength and weight reduction. However,
Not limited to such resins, various materials can be used as the base material, such as SUS, iron, and other composite materials with metals, alloys, resins, and the like in terms of mechanical strength and cost.

On the lower side of the substrate 22 (on the side of the member 3 to be charged), a fixing layer 222 having conductivity and capable of fixing a brush is formed. Since adhesion to the resin substrate 221 is required, the bonding surface of the resin substrate was formed so as to be appropriately roughened. An ohmic contact is made from the longitudinal end of the fixed layer 222 to connect the wiring. Wiring is fixed layer 22
2 from both ends, it was devised so that the effect of the voltage drop by the fixed layer 222 is not in the charged state as much as possible. The wiring makes it possible to apply a voltage between the charged object 3 and the fixed layer 222. The material of the fixed layer is largely determined by the constraints of the manufacturing method. The contact with the brush 23 is ohmic so that the contact resistance can be reduced as much as possible. Therefore, this time, the conductive resin used for the brush 23 was used by applying. However, this fixing layer has conductivity, and if the brush can be fixed, a low-melting-point metal such as Al, Cu, Au, or In, or another conductive resin can also be used.

The brush of the brush charger 5c will be described.
The brush 23 must be fixed to the base 22, fix the microprojections at the tip thereof, and support the stress applied between the base and the member to be charged by its elasticity.
The state in which the brush is functioning is shown in FIG. 7 as an image, but it is necessary that the brush be appropriately bent by stress. Thereby, it is possible to adjust the distance between the member to be charged and the minute projections to be as short as possible. In this case, the brush only needs to be partially in contact with the member to be charged and support the stress, and it is not necessary that the brush actively contact the member to be charged with a large area. The larger the contact area, the lower the contact resistance, and the better the charging ability by injection. Since non-contact type charging phenomena such as field emission greatly affect the space gap, the distance between the minute projection and the member to be charged should be as short as possible. For this purpose, the brush 23 needs to be bent as shown in FIG. In order for the brush 23 to bend as described above, it is necessary to optimize the pressing pressure, the density of the brush 23, and the strength (elastic force) of the brush. Also,
Its mechanical strength needs to be adjusted so as not to scrape the charged body 3. The elasticity of the brush is determined by its length, fineness, material and the like. This time, nylon was used. In addition, if it is easy to make a fiber shape, PET, PES, elastic epoxy resin, polyvinyl alcohol, vinyl chloride,
I think that is appropriate. Further, the charger 5c of the present invention is not limited to such a material, and can be formed.

As described above, the brush 23 has conductivity,
In addition, it is necessary to take measures so as not to have a large contact resistance between the fixed layer 222 and the minute projection. The brush 23 is made of a conductive nylon resin. 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. According to this method, conductivity can be more finely and uniformly obtained. In the former method, it is impossible to obtain non-uniformity of dispersion of the conductive fine particles or at least uniformity of the particles or less. As a result, among the fixed microprojections,
Depending on the distance from the conductive particles, some particles may not have conductivity with the base. In image charging, the order of micron order or less can be neglected, but in the present invention, minute protrusions in the present invention are considered to be as thin as one to two orders, so non-uniformity in this order should be carefully considered. There must be.

It is desired that the resistance value of the brush 23 is larger than the resistance value of the member 3 to be charged. This is necessary as a countermeasure against pinholes of the member 3 to be charged, and even if a minute protrusion or a brush contacts the pinhole of the member 3 to be charged, it is possible to avoid concentration of electric charges there. When the resistance value of the charger 5c is controlled by the base 22, the area where the voltage is reduced when the brush 23 is in contact with the pinhole is smaller when the resistance is controlled by the brush 23. For example, when the control is performed at the base of the charger 5c, 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 brush 23, there is no effect except for one brush supporting the short projection. In addition, a smaller resistance value is desired for the charging ability. This can be determined by considering that the resistance value enters the equivalent circuit in series. Thus, the brush 23
It is desired to optimize the resistance value of the above from these two viewpoints. By changing the amount of doped TCNQ and TTF, the resistance of the brush can be controlled.

The shape of the brush 23 is desired to have a high density of minute projections from the viewpoint of the charging ability of the charger 5c. Therefore, it is necessary to make the brush thinner and to increase the density. The electrification from the microprojections greatly depends on the distance between the microprojections and the member 3 to be charged. The smaller the distance, the better. A charger that satisfies the specifications of miniaturization and high density 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. In addition, a product having an appropriate shape must be designed in consideration of the service life, mechanical resistance, and the like.

The minute projections and CNTs may be the same as those described in the roller charger 5a of FIGS. 1 and 2, and redundant description will be omitted. The specification of such a brush-type charger 5c as “Embodiment 3 of the charger” will be described with reference to the schematic side view shown in FIG. The third embodiment is configured by combining the respective components described above. Since the manufacturing method and the like have been described above, a repeated description is omitted here. <Basic specifications> Substrate Material: ABS resin Width: 3 mm Pushing into charged object: 0.5 mm Fixed layer Nylon resin doped with TCNQ and TTF Brush Diameter: 10 μm, Length: 2 mm, Density: 120 / mm ² materials : Nylon fiber CNT doped with TCNQ and TTF Diameter: 10 to 25 nm, Length: 10 μm or more Material: Multi-walled carbon nanotube Synthesis method: Arc discharge Projection method: Oxygen plasma ashing method Conductive adhesive Material: Thermosetting epoxy-based conductive material Next, the applied voltage of the brush type charger 5c is reduced to three blocks 5c.
FIG. 10 shows an outline of specifications (three-stage blade brush type) divided into -1, 5c-2 and 5c-3.

FIG. 10 shows an outline of the charger 5c 'of the three-stage blade brush type as viewed from the side. A PET film 25 is interposed between the blocks to prevent short circuit between the blocks. Each potential is-
200, -400, and -500 V. Thereby, it was charged without discharging. <Basic specifications> Substrate Material: ABS resin Width: 3 blocks of 2 mm indentation into the object to be charged: 0.5 mm Insulation film PET film: 0.5 mm Fixed layer Nylon resin doped with TCNQ and TTF Brush Diameter: 10 μm, length Length: 2 mm, Density: 120 fibers / mm2 Material: Nylon fiber doped with TCNQ and TTF CNT Diameter: 10 to 25 nm, Length: 10 μm or more Material: Multi-walled carbon nanotube Synthesis method: arc discharge, purification: centrifugal separation method Combined use of ultrafiltration method Projection method: Oxygen plasma ashing method Conductive adhesive Material: Thermosetting epoxy-based conductive adhesive Applied voltage -200 V, -400 V, -500 V Charging capacity 30 cpm Next, a brush type charger (brush) FIG. 11 shows a schematic view of the roller type 5c ″) specification.

As shown in FIG. 11, the brush-type charger 5c ″ here is of a brush roller type, and the brush cloth described above, that is, each brush 29 made of nylon fiber with CNT 24 is fixed to the roller base 27. The rotation speed of the roller base 27 is set to three times the rotation speed of the member to be charged 3 and the rotation direction is reversed, thereby obtaining a charging ability of 60 cpm. <Basic specifications> Base material: SUS Radius: 10 mm Pushing into charged object: 0.5 mm Fixed layer NCN resin doped with TCNQ and TTF Brush Diameter: 10 μm, Length: 2 mm, Density: 120 / mm2 Material: Nylon fiber CNT doped with TCNQ and TTF Diameter: 10 to 25 nm, Length: 10 μm or more Material: Multi-walled carbon nanotube Synthesis method: Arc Electricity and purification: Combination of centrifugal separation method and ultrafiltration method Projection method: Oxygen plasma ashing method Conductive adhesive Material: Thermosetting epoxy-based conductive adhesive Applied voltage -500V Charging roller operation Charged object rotation speed 3 Double charging ability 60 cpm [2-D] Another embodiment of charger and charged object Next, another embodiment of the "charging device" and the "charged object" in consideration of the charging effect of the pinhole of the charged object 3 Add an explanation for the example.

FIG. 13 shows the use of a contact type brush type charger (brush roller type) 5d as Embodiment 4, wherein the conductive fibers used in the brush type charger 5d are made of carbon nanotubes. I have. The brush-type charger 5d of the present invention has a structure in which the resistance layer 32 is formed on the metal core 31 and the carbon nanotube 30 is held on the resistance layer 32. The brush-type charger 5d is mainly composed of the carbon nanotubes 30 and the OPC 3a to be charged.
In contact with the surface.

OPC3 as “Embodiment 3 of Charged Member”
“a” includes a drum-shaped Al substrate 3a1 and an organic photosensitive layer 3a2, and a charge injection blocking layer is provided between the Al substrate 3a1 and the organic photosensitive layer 3a2 as necessary.
Although not shown, the metal core 3 of the brush-type charger 5d is not shown.
Numeral 1 is connected to an external DC power supply, and charges the OPC 3a mainly by directly injecting electrons (that is, negatively charged charges) from the carbon nanotubes 30 into the organic photosensitive layer 3a2. Note that some of the charges are
Electrons are extracted from the organic photosensitive layer 3a by field emission.
2 may be charged.

The charge injection is performed directly at the contact portion between the contact-type charger 5d and the organic photosensitive layer 3a. Therefore, in order to obtain a practical injection speed, the contact-type charger 5d and the organic photosensitive layer 3a are charged.
The contact area of a must be increased. However, in general, the diameter of the conductive fiber of the charging brush is 10 to 2
A high-speed image forming apparatus in which the OPC 3a rotates at a high speed cannot secure a sufficient contact area. In addition to improving the injection speed, the actual OPC3a
The organic photosensitive layer 3a2 often has a pinhole,
It is necessary to suppress a voltage drop of the DC power supply caused by an overcurrent when the pinhole of the organic photosensitive layer comes into contact with the contact type charger.

The inventors of the present invention have conducted intensive studies on the above problems, and as a result, have reached the following invention. Here, the OPC 3a is in contact with the carbon nanotube 30 having a very fine structure, and the resistance layer 3 is located between the carbon nanotube 30 and the metal core.
2 intervening. In the brush-type charger 5d, the organic photosensitive layer 3a2 and the carbon nanotube 30 have a structure in which the carbon nanotube 30 is in contact with the organic photosensitive layer 3a2. Since the carbon nanotube 30 has an extremely small diameter, the current flowing from the pinhole of the organic photosensitive layer 3a2 has a large current density per carbon nanotube. Carbon nanotubes are heated when passing a one per ¹⁰ -8~- ^{9 A} more current in the atmosphere, since the distal end is oxidized by oxygen in the air will be exhausted, the carbon nanotubes 30 in contact with the pinhole instantaneous The tip becomes short, and the organic photosensitive layer 3a
Leave pinhole 2. That is, when the tip of the carbon nanotube 30 in contact with the pinhole of the organic photosensitive layer 3a2 is consumed, a situation in which the brush type charger 5d contacts the surface excluding the pinhole of the organic photosensitive layer 3a2 is automatically and instantaneously created. be able to.

Incidentally, the carbon nanotube 30 is formed of SP2
Even if the tip is worn out, the newly formed tip is still a six-membered ring of carbon atoms because it is composed only of the carbon atoms of the hybrid orbitals, and there is no change in the structure and no change in the charging characteristics. Further, even when the pinhole of the organic photosensitive layer 3a2 comes into contact with the carbon nanotube 30 and an overcurrent occurs, the resistance layer 32 serves as a protective resistor to suppress the magnitude of the overcurrent, so that a voltage drop of the DC power supply can be prevented.

By the above two effects, the influence of the pinhole can be further reduced as compared with the conventional contact type charger using an external coil and a medium resistance member (see FIG. 27).
PC can be charged uniformly. In addition, since the conductive fine particles are not dispersed on the surface of the organic photosensitive layer 3a2, the conductive fine particles do not absorb or scatter light, and the resolution and gradation of the image recording apparatus do not decrease. Further, the conventional OPC organic photosensitive layer is used to
The PC can be diverted as it is, and the cost of the image recording apparatus itself can be suppressed.

Regarding the charge injection speed, since the carbon nanotubes 30 have an extremely small diameter, they can be densely arranged on the resistance layer 32. In addition, since the carbon nanotube has great elasticity, it can bend when it comes into contact with the organic photosensitive layer 3a2, and can contact the organic photosensitive layer 3a2 not only at the tip of the carbon nanotube 30 but also at the side surface.

Since the carbon nanotubes 30 have semiconductive or metallic (that is, ohmic contact) conductive properties, it is possible to inject charges directly from the carbon nanotubes into the organic photosensitive layer 3a2. Therefore, in the brush-type charger 5d in which the carbon nanotubes 30 are connected to the metal core 31 via the resistance layer 32, the charge between the organic photosensitive layer and the brush-type charger is smaller than that of the conventional charging brush made of conductive fibers. , That is, a substantial contact area (hereinafter referred to as a conductive contact) can be significantly increased, and as a result, the charge injection speed can be significantly improved.

Even when the resistance layer 32 is provided, since the carbon nanotubes 30 are in contact with the organic photosensitive layer 102, the organic photosensitive layer 3a2 and the brush type charger 5d are compared with a conventional charging brush made of conductive fibers. In this case, the size of the conductive contact capable of transferring charges can be significantly increased, so that the charge injection speed does not decrease and a sufficient charging voltage can be applied to the OPC.

Next, components of the brush charger 5d will be described. The metal core 31 is made of a metal or an alloy such as Fe, Al, Cu, or stainless steel, is connected to an external DC power supply, and has a function of supplying a charge for charging the OPC 3a2 via the resistance layer 32 to the carbon nanotube 30. are doing. The resistance value of the resistance layer 32 is desirably 10 ⁴ to 10 ⁸ Ω in order to limit the magnitude of the overcurrent due to the pinhole of the organic photosensitive layer 3a2. If the resistance value is 10 ³ Ω or less, the overcurrent due to the pinhole increases, the voltage of the DC power supply decreases, and the charging voltage becomes non-uniform. If the resistance value is 10 ⁹ Ω or more, the resistance of the entire charging brush increases, the charge injection speed decreases, and the charging voltage of the OPC decreases.

The resistance layer 32 can be formed by forming an inorganic material having the above-described resistance value on a metal core.
For example, porous silicon, Fe, Ni, Co, Al, A
Ceramics such as alumina, silica, zeolite, etc., whose resistivity is controlled by adding conductive particles such as metals or alloys such as u, Ag and Pt, can be used. Since these materials have a high heat-resistant temperature and can form the carbon nanotubes 30 directly on the resistance layer by a thermal CVD (chemical vapor deposition) method,
The manufacturing process of the charging brush can be simplified.

The resistance layer 32 is formed by adding a resin such as Fe, Ni, Co, Al, Au, Ag, or a polymer resin such as polycarbonate, polyacrylate, polyterephthalate, or epoxy resin.
Addition of conductive particles such as metals or alloys such as Pt, or conductive inorganic materials such as graphite, fullerene, or carbon nanotubes, or polymer resin or the like that has been subjected to conductive treatment by forming a metal thin film such as Ni, Co, or Al on the surface. Alternatively, a material having a controlled resistivity may be formed on a metal core. When the above-described material is used, the resistance value is determined by the amount of the conductive particles added and the thickness of the resistance layer 32, so that the resistance value can be controlled very easily, and a resistance layer having a desired resistance value can be easily obtained. Can be.

Further, the material of the above-described resistance layer 32 is applied or sprayed onto the metal core 31 or the metal core 31 is coated.
Is dipped in the material of the resistance layer to form the resistance layer, so that the manufacturing cost of the resistance layer 32 can be reduced. The size of the conductive particles may be any size as long as it is easy to produce, and several μm to several hundred μm is appropriate for metal, alloy, polymer resin, graphite, etc., and several nm for fullerene or carbon nanotube. １1 μm is good.

The carbon nanotubes 30 include single-walled carbon nanotubes and multi-walled carbon nanotubes. The single-walled carbon nanotube has a diameter of 0.7 to 50 nm and an axial length (hereinafter abbreviated as length) of 10 nm to 1 mm. The size that can be easily synthesized is 0.7 to 5 in diameter.
nm, and the length is 30 nm to 100 μm. On the other hand, the multi-walled carbon nanotube has a diameter of 1 to 500 nm and a length of 10 nm to 1 mm.
Both single-walled and multi-walled carbon nanotubes are in the form of very fine fibers having an extremely large aspect ratio. Here, the carbon nanotubes 30 are not limited to the size range described above, and any carbon nanotubes 30 having a diameter of less than 1 μm are included in the present invention.

[0157] Next, a method for producing the above-described carbon nanotube will be described along [a] and [b], and a method for producing a brush-type charger using the carbon nanotube will be described along [c] and [d]. [a] Single-walled carbon nanotubes are made of Fe, Co, Ni, Ru, Rh, Pd, Os, I
Using a composite rod mixed with a metal catalyst such as r, Pt, La, Y, etc., using a graphite rod as a cathode, 100
It is synthesized by arc discharge in a He or H2 atmosphere of about 700 Torr. Single-walled carbon nanotubes are soot on the inner wall of the chamber depending on the type of metal catalyst (chamber soot)
Or it is present in the soot on the cathode surface (cathode soot). Further, the composite rod was heated to 1000 to 1400 ° C. in an electric furnace, and Nd: YAG was applied in an Ar atmosphere of 500 Torr.
Single-walled carbon nanotubes may be synthesized by irradiating a pulsed laser. 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.

[B] On the other hand, for the multi-walled carbon nanotubes, graphite rods were used for both
It synthesize | combines using arc discharge in He atmosphere of orr.
The multi-walled carbon nanotube is located at the center of the columnar deposit on the cathode. It can also be obtained by thermally decomposing hydrocarbons such as benzene, ethylene and acetylene at 1000 to 1500 ° C. under a H 2 gas flow. Since the multi-walled carbon nanotubes also contain various impurities after synthesis, it is preferable that the multi-walled carbon nanotubes be dispersed in an aqueous solution to which an organic solvent or a surfactant is added, and then purified to high purity by a centrifugation method or an ultrafiltration method. The tip of the carbon nanotube may be either a closed tube or an open tube. Further, a catalyst layer may be formed on the resistance layer, and carbon nanotubes may be directly formed on the resistance layer by a thermal CVD method.

[C] Next, a method of manufacturing the brush type charger 5d will be described. FIGS. 14A to 14D show the brush type charger 5d.
The outline of a part of is shown. The brush-type charger 5d has a columnar structure, and the carbon nanotube 30 is a metal core 3d.
It is assumed that it is held on all the side surfaces. (A) A metal core 31 made of a metal or an alloy such as SUS, Al, Fe, Cu, or the like is formed of Fe, Ni, Co, Al, Au, Ag,
Add conductive particles such as metals or alloys such as Pt, or conductive inorganic materials such as graphite, fullerene, or carbon nanotubes, or polymer resin or the like that has been subjected to conductive treatment by forming a metal thin film such as Ni, Co, or Al on the surface. Then, the resistive layer 32 having a predetermined thickness is formed by dipping in a polymer resin such as polycarbonate, polyacrylate, polyterephthalate, and epoxy resin whose resistivity is controlled.

The resistance value of the resistance layer 32 is as described above.
It is controlled by the amount of conductive particles added and the thickness of the resistance layer. (B) Then, a conductive adhesive 33 is applied to the resistance layer 32 to a thickness of 2
(C) The carbon nanotubes 30 are sucked up and brought into contact with the resistance layer 32 by using electrostatic force, and (d) the conductive adhesive 33 is further thermally cured, so that the carbon nanotubes 30 are formed on the resistance layer 32. Then, the brush charger 5d is completed.

[D] Another method of manufacturing the brush-type charger 5d is shown in FIG. FIG. 15 shows a part of the cross section of the brush-type charger 5d. The brush-type charger 5d has a columnar structure, and the carbon nanotubes 30 are held on all side surfaces of the metal core 31. I do. (A) A metal core 111 made of a metal or an alloy such as SUS, Al, Fe, Cu, or the like is made of Fe, Ni, Co, Al, Au, A
g, Pt or other metal or alloy, or graphite, fullerene, conductive inorganic material such as carbon nanotubes, or conductive particles such as polymer resin that has been subjected to conductive treatment by forming a metal thin film of Ni, Co, Al, etc. on the surface. The resistive layer 32 having a predetermined thickness is formed by dipping in a polymer resin such as polycarbonate, polyacrylate, polyterephthalate, and epoxy resin which has been added to control the resistivity.

(B) Thereafter, polymethylphenylsilane 34 is applied to the resistance layer 34 to a thickness of 0.1 to 3 μm, and irradiated with light having a wavelength of about 400 nm by an ultra-high pressure mercury lamp. Break the bond. (C) Then, the resistance layer 32 is immersed in a solution (abbreviated as an IPA solution) 35 in which carbon nanotubes are dispersed in isopropyl alcohol, and the metal core 31 is connected to an external power supply 37 using the Al electrode as the counter electrode 36 to apply a negative voltage. By applying the voltage, the carbon nanotubes 30 are brought into contact with the resistance layer 32 by electrophoresis.

The carbon nanotubes 30 move in a direction parallel to the applied electric field, and come into contact with the
It is pierced and immobilized in polymethylphenylsilane with broken Si bonds (hereinafter abbreviated as electrophoresis). In order to fix the carbon nanotubes 30 to all of the resistance layers 32 on the side surfaces of the metal core 31, the metal core 31 may be rotated in the IPA solution in the lengthwise circumferential direction.

(D) After that, the resistance layer 32 is made IPA solution 35
And the isopropyl alcohol is evaporated to complete the brush-type charger 5d.

[E] The brush type charger 5d is shown in FIG.
It can also be produced by the methods (a) to (d). FIG. 16 shows an outline of a part of the brush-type charger 5d.
The brush-type charger 5d has a columnar structure, and the carbon nanotubes 30 are held on all side surfaces of the metal core 31.

(A) A metal core 31 made of a metal or alloy such as SUS, Al, Fe, Cu, etc. is made of Fe, Ni, Co, Al,
Conductivity of metals and alloys such as Au, Ag and Pt, or conductive inorganic materials such as graphite, fullerene, and carbon nanotubes, or conductive polymers such as polymer resin formed by forming a metal thin film such as Ni, Co, or Al on the surface The resistive layer 32 having a predetermined thickness is formed by adding the particles and dipping in a polymer resin such as polycarbonate, polyacrylate, polyterephthalate, or epoxy resin whose resistivity is controlled.

The resistance value of the resistance layer 32 is as described above.
It is controlled by the amount of conductive particles added and the thickness of the resistance layer. (B) Thereafter, a holding layer 38 made of a polymer resin containing the carbon nanotubes 30 is formed on the resistance layer 32 via the conductive adhesive 33. As a material of the protective layer 38, a general polymer resin is used. For example, polycarbonate, polyacrylate, polyterephthalate, epoxy resin, and the like are preferably used. The protective layer 38 is preferably formed by coating or dipping.

Note that the carbon nanotubes 30 may or may not be exposed on the surface of the protective layer 38. (C) Thereafter, the holding layer 38 is mechanically polished so that the tips of the carbon nanotubes 30 protrude from the holding layer 38, thereby completing the brush-type charger 5d. When the protective layer 38 is mechanically polished with abrasive grains such as alumina, only the relatively soft polymer resin is selectively polished, and the carbon nanotube 30 is polished.
Is not polished. As a result, a structure in which the carbon nanotubes 30 protrude from the surface of the protective layer 150 is finally obtained.

If the length of the carbon nanotubes 30 protruding from the protective layer 38 is 0.1 μm or more, sufficient charging ability as a brush type charger can be secured. According to this method, since the alignment process of the carbon nanotubes 30 such as electrostatic adsorption or electrophoresis is not required, the manufacturing cost of the brush charger 5d can be reduced. Since the carbon nanotubes 30 are embedded in the polymer resin of the protective layer 38, the carbon nanotubes are strongly held by the resistance layer 32, and the brush type charger 5d is
The carbon nanotubes 30 are less likely to be separated from the resistance layer 32 while sliding on 3a, and the long-term stability of the brush-type charger is improved.

[F] The brush charger 5d can also be manufactured by the method shown in FIG. This method uses heat C on the resistance layer 32.
This is a method in which the carbon nanotubes 30 are directly formed by the VD method, and the manufacturing cost of the brush-type charger 5d can be suppressed. For example, when Fe is used as the catalyst layer 39, (a) Fe, Ni, Co, Al, Au, Ag,
TEOS to which conductive particles such as metals and alloys such as Pt are added
The solution is applied and then heated at 450 ° C. to form a resistance layer 3 made of a silicon oxide film having a desired resistance value on the metal core 31.
Form 2

As the resistance layer 32, ceramics such as alumina and zeolite whose resistivity is controlled by adding porous silicon or conductive particles can be used. (B) Then, Fe is formed on the resistance layer 32 by a vacuum evaporation method or a sputtering method so as to have a thickness of 2 to 40 nm,
The catalyst layer 39 is formed. When the metal core 31 has a columnar structure, the catalyst layer 39 is formed while rotating the metal core, and the catalyst layer 39 is formed on all surfaces on the resistance layer 32. (C) After that, the metal core 31 on which the catalyst layer 32 is formed is inserted into the quartz tube 41, He gas is introduced, and annealing is performed at 700 to 800 ° C. for 10 minutes using the electric furnace 42 to thereby form the catalyst layer 3
9 into fine particles of several tens of nm in size. After that, C2H2 gas is introduced into the quartz tube 41, and the substrate temperature is set to 650 to 650.
C 2 H 2 is thermally decomposed at 750 ° C. to grow the carbon nanotubes 30 on the catalyst layer 39. Also C2H2
An inert gas such as He or Ar or an H2 gas may be introduced at the same time as the gas, and CVD may be performed at any of reduced pressure or atmospheric pressure. Further, plasma may be generated in the quartz tube 41 to promote thermal decomposition of C2H2. At a growth temperature of 650 ° C., the carbon nanotubes 30 grow on the resistance layer 32 in random directions, but at 675 to 750 ° C., the carbon nanotubes 30 grow in a direction substantially perpendicular to the resistance layer 32. (D) After the carbon nanotubes 30 of a desired length have been grown on the catalyst layer 39, the C2H2 gas in the quartz tube 41 is replaced with an inert gas such as He or Ar, and cooled to room temperature to cool the metal core 31. The take-out brush charger 5d is completed.

Further, the charging brush is filled with water or an organic solvent such as ethyl alcohol, isopropyl alcohol, acetone, and toluene, immersed in an ultrasonic cleaning tank equipped with an ultrasonic oscillator, and ultrasonic vibration is applied thereto to form a bundle. The formed carbon nanotubes 30 may be divided into individual carbon nanotubes. After the carbon nanotubes 30 are further grown, they may be heated at 600 to 700 ° C. in an oxidizing atmosphere to remove slightly precipitated carbon particles and the like. It may be spread thinly on top, and the adhesive may be cured to improve the fixing strength between the carbon nanotube 30 and the catalyst layer 39 and the adhesion strength between the catalyst layer 39 and the resistance layer 32. As the catalyst layer 39, other than Fe, Ni, Co, Fe alloy, Ni alloy, Co alloy, Fe oxide, Ni oxide, Co oxide can be used, and Fe compound, Ni compound, Co compound can be dissolved in a solvent. The catalyst layer 39 may be formed by coating the resistance layer 32 and then evaporating the solvent. In addition, the above metals, alloys,
The oxides and compounds may be used alone, but a mixture of several kinds of catalysts may be used.

In this embodiment, the catalyst layer 39 is formed on the entire surface of the resistance layer 32. However, in the case of the brush-type charger 5d using a relatively long carbon nanotube, the catalyst layer 39 is arranged discretely and the carbon nanotube 30 is formed. May be formed discretely. In that case, it is preferable to determine the distance of the catalyst layer 39 in consideration of the degree and length of bending of the carbon nanotube. Further, the carbon nanotubes 30 are similarly grown on the catalyst layer 112 by using an unsaturated hydrocarbon gas such as C ₂ H ₄ or a saturated hydrocarbon gas such as CH ₄ instead of the C ₂ H ₂ gas.

C ₂ H ₂ gas, C ₂ H ₄ gas, CH ₄
The gas or the like may be used alone, but may be used as a mixture, or may be used after being diluted with an inert gas such as Ar or He. Note that the temperature range in which the carbon nanotubes 30 grow from the resistance layer 32 varies depending on the type of the catalyst layer 39 and the type of the hydrocarbon gas.

According to this method, the carbon nanotubes can be grown directly from the resistance layer 32, so that the process of separating and purifying the carbon nanotubes is not required, and the cost of the brush charger 5d can be reduced. Further, since a relatively long carbon tube can be obtained, the number of conductive contacts increases, and the charge injection speed improves. In addition, although this example demonstrated the brush-type charger 5d of a roll shape,
Even with a fixed brush, the effects of the present invention can be realized similarly,
The shape of the charging brush is not limited. In addition, the brush type charger 5d is connected to a DC power supply, but the power supply is not limited to DC, and DC and AC may be superimposed.

Next, with reference to FIG. 13, the OPC 3a as a member to be charged (photosensitive member) used here will be described. A hole injection blocking layer in which a drum-shaped Al substrate 3a1 titanium oxide fine particles are dispersed in a binder resin is formed with a thickness of 1 to 5 μm by dip coating, and thereafter, a charge generation layer (hereinafter abbreviated as CGL) and a charge transport layer (hereinafter abbreviated as CGL) C
(Abbreviated as TL) to form a laminated organic photosensitive layer 3a2. CGL is made by dispersing a charge generating material (hereinafter abbreviated as CGM) in a binder resin such as a petital resin, a thermosetting modified acrylic resin, or a phenol resin.
0.1-1μm thickness by dipping coating method
Formed.

As CGM, squarylium dye, metal-free phthalocyanine, metal phthalocyanine, azulenium salt dye, azo pigment and the like having a sensitivity around the wavelength of 740 to 780 nm are available. System, perylene system, azo pigment system or the like can be used. The CTL is formed by dispersing a hole carrier transport material (hereinafter abbreviated as CTM) in a binder resin such as a bisphenol-based polycarbonate resin, and has a film thickness of about 10 to 40 μm and is formed by a dipping coating method. As the CTM, oxadiazole derivatives, pyrarizone derivatives, triphenylmethane derivatives, oxazole derivatives, triarylamine derivatives, butadiene derivatives and the like are used.

In this embodiment, the OPC 3a2 using holes among carriers generated by light is used. However, CGMs for generating electrons and CTMs for transporting electrons have been developed to some extent. OPC using electrons does not matter. In this case, the positive and negative DC power supplies are used in reverse, and the DC power supply is used for positive charging. In this example, the description has been made by taking the function-separated type OPC 3a as an example, but the present invention is not limited to the function-separated type.
A single-layer type OPC may be used. In this example, the drum-shaped OPC 3a is used, but instead of the Al base, a belt having a conductive layer formed on the surface is employed, and the belt-shaped OPC 3a is used.
C may be used. Also, a sheet-like OPC may be used.

Further, the contact-type charger here is not limited to the one used for the OPC 3a, but may be a Se-based charger, a
Since the same contact type charger can be used even with inorganic photoreceptors such as -Si, ZnO, etc., the type of the photoreceptor does not limit the claims of the contact type charger of the present invention.

[2-E] Another contact-type charger of the present invention, "Embodiment 5 of the charger" will be described with reference to FIG. Figure 1
Reference numeral 8 denotes a brush-type charger 5e as a contact-type charger, which has a structure in which carbon nanotubes 44 are bonded to conductive fibers 43. The brush-type charger 5e of the fifth embodiment has a structure in which a resistance layer 42 is formed on a metal core 41, and a conductive fiber 43 to which carbon nanotubes 44 are bonded is held on the resistance layer 42.

The brush charger 5e is mainly in contact with the surface of the OPC 3a by the carbon nanotubes 44.
Note that the resistance value of the resistance layer 42 is 10 ⁴ to 1
It is desirable that the 0 ⁸ Ω. OPC as an object to be charged
3a is a drum-shaped Al base 3a1 and an organic photosensitive layer 3a2.
A charge injection blocking layer is provided between the Al base 3a1 and the organic photosensitive layer 3a2 as required.

Although not shown, the brush type charger 5
The metal core 41 of e is connected to an external DC power supply, and charges the OPC 3 mainly by directly injecting electrons from the carbon nanotubes 44 into the organic photosensitive layer 3a2. Note that a part of the charge may charge the organic photosensitive layer 3a2 by extracting electrons from the carbon nanotube 620 by field emission. Also in Example 5, when the carbon nanotubes 44 contact the pinholes of the organic photosensitive layer 3a2,
The tip of the carbon nanotube 44 generates heat due to an overcurrent flowing through the carbon nanotube 44, is oxidized by oxygen in the air, and the tip is consumed. Move away from the pinhole.

Further, even when the pinholes of the organic photosensitive layer 3a2 come into contact with the carbon nanotubes 44 and an overcurrent occurs, the resistance layer 42 serves as a protective resistor and suppresses the magnitude of the overcurrent, thereby preventing a voltage drop of the DC power supply. it can. 2 above
By the two effects, the influence of the pinhole can be further reduced, and the OPC can be uniformly charged. In addition, since the conductive fine particles are not dispersed on the surface of the organic photosensitive layer, light is not absorbed or scattered by the conductive fine particles, and the resolution and gradation of the image recording apparatus are not reduced. Further, the OPC can be diverted as it is by using the conventional OPC organic photosensitive layer 3a2, and the cost increase of the image recording apparatus itself can be suppressed.

Regarding the charge injection speed, also in this example, since the carbon nanotubes 44 have a very small diameter,
It is possible to arrange them densely on the resistance layer 42. Further, since the carbon nanotubes 44 have great elasticity, they can bend when they come into contact with the organic photosensitive layer 3a2, and can contact the organic photosensitive layer 3a2 not only at the tip but also at the side surfaces of the carbon nanotubes 44. Therefore, even when the resistive layer 42 is provided, the conductive contact between the organic photosensitive layer 3a2 and the brush-type charger 5e that can transfer charges can be significantly increased, and the charge injection speed can be significantly improved. As a result, a sufficient charging voltage can be applied to the OPC 100.

Next, components of the brush-type charger 5e according to the fifth embodiment will be described. As the metal core 41, the resistance layer 42, and the carbon nanotubes 44, the same ones as in Example [2-D] can be used. As the conductive fibers 43, carbon black or metal fine particles are dispersed in rayon resin, nylon resin, acrylic resin, polyester resin, or the like, and then spun into a fiber shape, or tetracyanoquinodimethane (TCNQ) A polymer resin obtained by spinning a polymer resin in which a charge transfer complex composed of an electron-accepting compound such as the above and an electron-donating compound such as tetrathiafulvalene (TTF) is substituted by a polymer network is used.

Next, an example of a method of manufacturing the brush type charger 5e will be described with reference to FIGS. 18, 19 (a) to 19 (e). FIG. 18 schematically illustrates a part of the brush-type charger 5e. The brush-type charger 5e has a columnar structure, and the conductive fibers 43 are connected to the entire surface of the resistance layer 42. And (A) A metal core 41 made of a metal or alloy such as SUS, Al, Fe, Cu or the like is formed by Fe, Ni, Co, Al, Au, Ag,
Addition of conductive particles such as metals or alloys such as Pt, or conductive inorganic materials such as graphite, fullerene, or carbon nanotubes, or polymer resin or the like that has been subjected to conductive treatment by forming a metal thin film such as Ni, Co, or Al on the surface. Then, the resistive layer 42 having a predetermined thickness is formed by dipping in a polymer resin such as polycarbonate, polyacrylate, polyterephthalate, and epoxy resin whose resistivity is controlled.

(B) Then, the conductive fibers 4 are formed on the resistance layer 42.
3 is planted by electric flocking. As the conductive fiber 43, conductive rayon, conductive nylon, conductive polyester, or the like having a diameter of 5 to 20 μm can be used.
It is better to be about m2. Alternatively, the conductive fiber 42 may be made into a pile ground, cut into a tape shape, and then wound around the resistance layer 42. (C) Then, a conductive adhesive 45 is applied only to the tip of the conductive fiber 43 with a thickness of 2 to 10 μm. (E) Thereafter, the conductive adhesive 45 is thermally cured to fix the carbon nanotubes 44, thereby completing the brush type charger 5e.

Instead of the conductive adhesive, the conductive fibers themselves may be heated and fused with the carbon nanotubes to fix them. Further, after bonding the carbon nanotubes 44 to one long conductive fiber 43 with a conductive adhesive 45, the conductive fiber is cut into 1 to 2 mm, and the conductive fiber 43 is planted on the resistance layer 42 by electric flocking to form a brush. Type charger 5e
It is good. Further, the long conductive fiber to which the carbon nanotubes 44 are bonded may be made into a pile, cut into a tape shape, and then wound around a resistance layer to form a brush charger 5e.

Another method of manufacturing the brush-type charger 5e of the fifth embodiment will be described with reference to FIGS. FIG. 20 schematically shows a part of the brush charger 5e. The brush charger 5e has a columnar structure, and the conductive fibers 43 are connected to the entire surface of the resistance layer 42. And

(A) A metal core 41 made of a metal or alloy such as SUS, Al, Fe, Cu, etc., is made of Fe, Ni, Co, Al,
Conductivity of metals and alloys such as Au, Ag and Pt, or conductive inorganic materials such as graphite, fullerene, and carbon nanotubes, or conductive polymers such as polymer resin formed by forming a metal thin film such as Ni, Co, or Al on the surface Particles are added and dipped in a polymer resin such as polycarbonate, polyacrylate, polyterephthalate, epoxy resin or the like whose resistivity is controlled to form a resistance layer 42 having a predetermined thickness.

(B) Then, the conductive fibers 4 are formed on the resistance layer 42.
3 is planted by electric flocking. As the conductive fiber 43, conductive rayon, conductive nylon, conductive polyester, or the like having a diameter of 5 to 20 μm can be used.
It is better to be about m2. Alternatively, the conductive fiber 43 may be made into a pile ground, cut into a tape shape, and then wound around the resistance layer 42. (C) After that, polymethylphenylsilane 46 is applied to the tip of the conductive fiber 43 only at a thickness of 0.1 to 3 μm, and irradiated with light having a wavelength of about 400 nm by an ultra-high pressure mercury lamp, and the Si- (D) Then, the conductive fiber 43 is immersed in a solution (abbreviated as an IPA solution) 47 in which carbon nanotubes are dispersed in isopropyl alcohol, and the Al electrode is used as a counter electrode 48 to connect the metal core 41 to an external power supply. By connecting and applying a negative voltage, the carbon nanotubes 44
Touch 3 The carbon nanotubes 44 move in a direction parallel to the applied electric field, come into contact with the conductive fibers 43, and break the Si-Si bond.
6 is pierced and fixed.

(E) Thereafter, the conductive fiber 43 is pulled up from the IPA solution 47, and isopropyl alcohol is evaporated to complete the brush type charger 5e. Further, as described above, the carbon nanotubes 44 are fixed to one long conductive fiber 43 by electrophoresis, and then the conductive fiber is cut into 1 to 2 mm. It is good also as a brush type charger 5e by planting.

Further, it is also possible to use a long conductive fiber in which carbon nanotubes are immobilized by an electrophoresis method as a pile ground, cut it into a tape shape, and wind it around a resistance layer to form a brush charger 5e. As the OPC used in this example, the same OPC 3a as that of “Example 3 of the member to be charged” described in [2-D] can be used.

[2-F] Embodiment 6 of the contact-type charger of the present invention will be described with reference to FIG. The contact-type charger of this example has a shape of a charging roller. The charging roller 5f according to the sixth embodiment shown in FIG. 21 has a structure in which a resistance layer 52 is formed on a metal core 51, and the tips of the carbon nanotubes 50 held in the resistance layer 52 project from the resistance layer 52. The charging roller 5f is mainly in contact with the surface of the OPC 3a serving as a member to be charged by the carbon nanotube 50. The OPC 3a is composed of a drum-shaped Al base 3a1 and an organic photosensitive layer 3a2, and the same OPC 3a as in "Example 3 of a member to be charged" is used.

Although not shown, the charging roller 5f
The metal core 51 is connected to an external DC power supply, and charges the OPC 3a mainly by directly injecting electrons from the carbon nanotube 50 into the organic photosensitive layer 3a2. Some of the charges may be such that electrons are extracted from the carbon nanotubes 50 by field emission to charge the organic photosensitive layer 3a2. Also in this example, when the pinhole of the organic photosensitive layer 3a2 also comes into contact with the carbon nanotube 50, the tip of the carbon nanotube 50 generates heat due to an overcurrent flowing through the carbon nanotube 50, is oxidized by oxygen in the air, and the tip is consumed. The tip of the carbon nanotube 50 in contact with the pinhole is instantaneously shortened and separates from the pinhole of the organic photosensitive layer 3a2.

Further, even when the pinholes of the organic photosensitive layer 3a2 come into contact with the carbon nanotubes 50 to cause an overcurrent,
Since the resistance layer 52 serves as a protection resistor and suppresses the magnitude of the overcurrent, a voltage drop of the DC power supply can be prevented.

With the above two effects, the influence of the pinhole can be further reduced, and the OPC 3a can be uniformly charged. In addition, since the conductive fine particles are not dispersed on the surface of the organic photosensitive layer, light is not absorbed or scattered by the conductive fine particles, and the resolution and gradation of the image recording apparatus are not reduced. Further, the OPC 3a using the conventional OPC organic photosensitive layer can be diverted as it is, and the cost increase of the image recording apparatus itself can be suppressed.

Regarding the charge injection speed, also in this example, since the carbon nanotube 50 has a very small diameter,
It is possible to arrange them densely on the resistance layer 52. Further, since the carbon nanotube 50 has large elasticity, the carbon nanotube 50 can bend when it comes into contact with the organic photosensitive layer 3a2, and can contact the organic photosensitive layer 3a2 not only at the tip but also at the side surface of the carbon nanotube 50. Therefore, even when the resistive layer 52 is provided, the conductive contact between the organic photosensitive layer 3a2 and the brush-type charger 5f that can transfer charges can be significantly increased, and the charge injection speed can be significantly improved.

As a result, a sufficient charging voltage can be applied to the OPC 3a. Furthermore, carbon nanotube 50
Is embedded in the resistance layer 52, and the carbon nanotubes 5
The carbon nanotube 50 is firmly connected to the resistance layer 52 because the tip of the carbon nanotube 50 protrudes from the resistance layer 52, and the carbon nanotube 50 is brush-charged while the brush-type charger 5f slides on the OPC 3a. The long-term reliability is improved without detaching from the vessel 5f. Also, by dispersing the carbon nanotubes 50 in the resistance layer 52 to fix the carbon nanotubes,
Since the process of aligning and fixing the carbon nanotubes becomes unnecessary, the cost reduction of the brush-type charger 5e is expected.

Next, a description will be given of the cross-sectional structural members of the brush-type charger 5f used in this embodiment.

As the metal core 51 and the carbon nanotube of this example, the same one as the carbon nanotube 30 described in [2-D] can be used. The resistance layer 52 is made of the organic photosensitive layer 3a2.
In order to limit the magnitude of overcurrent due to the pinhole of
The resistance value is desirably 10 ⁴ to 10 ⁸ Ω. Resistance value is 10 ³
Below Ω, the overcurrent due to the pinhole becomes large, the voltage of the DC power supply decreases, and the charged voltage becomes non-uniform. If the resistance value is 10 ⁹ Ω or more, the resistance of the entire charging brush increases, the charge injection speed decreases, and the charging voltage of the OPC decreases.

The resistance layer 52 has a structure in which the carbon nanotubes 50 are dispersed in a polymer resin such as polycarbonate, polyacrylate, polyterephthalate, and epoxy resin. At least a part of the dispersed carbon nanotubes 920 is a resistance layer. Although it protrudes from the surface of 52,
Fe, Ni, Co, A besides the carbon nanotube 50
Metals or alloys such as l, Au, Ag, Pt, or conductive inorganic materials such as graphite and fullerene, or N on the surface
Conductive particles such as a polymer resin which has been subjected to conductive treatment by forming a metal thin film of i, Co, Al or the like may be added. When these conductive particles are added to the polymer resin, the number of carbon nanotubes 50 protruding from the surface of the resistance layer 912 and the resistance value of the resistance layer 52 can be controlled independently, so that the resistance value of the resistance layer 52 can be optimized. It has the advantage of being easy. The size of the conductive particles may be any size as long as it is easy to produce, and several μm if it is a metal, alloy, polymer resin, graphite, or the like.
To several hundred μm is appropriate.
m to 1 μm is good.

Next, a method of manufacturing the brush-type charger 5f of this embodiment will be described with reference to FIGS. FIG. 22 schematically shows a part of the brush-type charger 5f. The brush-type charger 5f has a columnar structure, and the carbon nanotubes 50 protrude from the entire surface of the resistance layer 52. (A) A metal core 51 made of a metal or alloy such as SUS, Al, Fe, Cu, etc. is dipped in a polymer resin such as polycarbonate, polyacrylate, polyterephthalate, epoxy resin or the like in which carbon nanotubes 50 are dispersed. A resistance layer 52 having a thickness is formed.

The polymer resin includes Fe, Ni, Co, Al, Au, Ag, P
Metals or alloys such as t, or conductive inorganic materials such as graphite or fullerene, or conductive particles such as a polymer resin or the like that has been subjected to conductive treatment by forming a metal thin film such as Ni, Co, or Al on the surface may be added. . The resistance value of the resistance layer 52 is controlled by the amount of carbon nanotubes and conductive particles added and the thickness of the resistance layer. (B) Thereafter, the resistance layer 52 is mechanically polished so that the tips of the carbon nanotubes 50 protrude from the resistance layer 52, thereby completing the brush charger 5e.

When the resistance layer 52 is mechanically polished with abrasive grains such as alumina, only the relatively soft polymer resin is selectively polished, and the carbon nanotube is not polished. As a result, a structure in which the carbon nanotubes 920 protrude from the surface of the resistance layer 52 is finally obtained. Note that the resistance layer 52
The length of the carbon nanotube 50 projecting from
If it is not less than μm, sufficient charging ability as a charging roller can be secured. Although the present embodiment has been described using the roller shape of the brush type charger 5e, there is no problem with the shape of the charging blade, and the shape of the contact type charger limits the scope of the present invention. is not.

[2-G] Each contact type charger 5d of the present invention
5f will be described. The above-described “Electric Charger Examples 4 to
The test chart was copied by mounting one of the contact-type chargers of "6" and a DC power supply of -500 V as a charging system of the OPC as a member to be charged in a copying machine. The development was a binary development of black and white, and the gradation was indicated by the number of dots. The OPC used this time has a size of 1 on the surface of the organic photosensitive layer.
There were about 10 to 40 pinholes of 0 to 20 μm.
As a result of copying using a copying machine (see FIG. 1) as an image forming apparatus on which one of the contact-type chargers of “Chargers 4 to 6” is mounted, charging is performed on the entire surface of the OPC to be charged. No unevenness occurred, and the effect of the pinhole did not appear. Further, the resolution and gradation were improved as compared with a normal analog display copying machine, and good copying was performed over the entire test chart. In the chargers of "Examples 4 to 6 of chargers", ozone and NOx were hardly detected during the charging process of the photoconductor.

Therefore, it was confirmed that the copier equipped with the charger of the present invention can perform good image recording without generating ozone or NOx even when the organic photosensitive layer of the OPC has a pinhole. . The same effect can be expected in an image forming apparatus such as a printer and a facsimile.

[2-H] As described in [2-D] to [2-G], the chargers of "Embodiments 4 to 6 of the charger" were charged mainly by charge injection. . When a higher charging potential (about 600 V to 1 kV) is required, O
The charging of the PC is mainly performed by corona discharge in the minute gap of the charger that is in contact with the OPC. Also in the charger of the present invention, when a voltage equal to or higher than the discharge starting voltage Vth is applied to the minute gap between the carbon nanotube and the OPC, corona discharge occurs in the minute gap between the carbon nanotube and the OPC, and the OPC is charged. .

In particular, since the carbon nanotube has a very fine needle-like shape, the uneven electric field at the tip of the carbon nanotube becomes strong, and the discharge starting voltage Vth can be reduced. Further, since carbon nanotubes cause field emission at atmospheric pressure, electrons due to field emission serve as a trigger of corona discharge, and have the effect of further lowering Vth. [2
In each of the chargers described in [-D] to [2-F], Vth was measured with a charging brush. It was found that the applied voltage could be lower than that of the vessel.

[0210] The corona discharge in the minute gap causes OP.
As a result of measuring ozone and NOx generated when C was charged, the charging brush of Example 2 was more ozone and NOx than the contact type charger in which the carbon nanotube was not held.
There were few. This is because corona discharge occurs only at the tip of the carbon nanotube, and the charging brush of Example 2 has a narrow discharge space and a small applied voltage, so that ozone and N
It is considered that generation of Ox was suppressed.

Further, as a result of actually performing copying by a copying machine equipped with a charging brush such as "Example 5 of a body to be charged", uneven charging does not occur on the entire OPC surface, no influence of pinholes appears, and ordinary The resolution and gradation were improved as compared with the analog display copier, and good copying was performed over the entire test chart. Note that the charger here is not limited to a charging method such as charge injection, electric field emission, or corona discharge in a minute gap. The same applies to all contact-type chargers including the structure of the present invention. .

[3] The transfer device 8 will be described. Figure 1
In the copying machine as the image forming apparatus 1 shown in FIG.
3 and a charge providing material 14 for supplying transfer charge to the transfer belt
And a power supply 15. [3-A] FIG. 23 shows a copying machine 1b on which the first transfer device 8b is mounted, as "Embodiment 1 of transfer device".

The copying machine 1b has the same configuration as the copying machine 1 shown in FIG. As a charge-imparting material of the transfer device 8b, a blade-type one having CNT protruded from the surface was manufactured.

[0214] The manufacturing method is described below. A carbon nanotube is manufactured using the above-described technique. Helium was used as an atmosphere gas, and the anode and the cathode were synthesized by a DC arc discharge method using graphite rods at a pressure of 500 Torr. The current amount was about 100 A, the electrode diameter was 1 cm, and the distance between the electrodes was about 1 mm. A columnar deposit having a diameter of about 1 cm was formed at the tip of the cathode, and a bundle of multi-walled carbon nanotubes was observed.

Since the multi-walled carbon nanotubes 62 contain various impurities after synthesis, they are dispersed in an aqueous solution to which an organic solvent or a surfactant is added, and then purified to a high purity by centrifugation or ultrafiltration. Good to do. This multi-walled carbon nanotube is mixed with an epoxy resin,
It was cured by heating for 1 hour to form a CNT resin matrix on the Al substrate. Then, alumina abrasive (particle size 0.3μ)
m) and polishing using a urethane foam polishing pad,
The multi-walled carbon nanotubes 14 protruded from the surface of the carbon nanotube resin matrix. The multi-walled carbon nanotubes had a length of 0 to several μm and protruded almost randomly on the surface.

In this way, a blade-like charge applying material 61 having a width of 2 mm, which is the same as the nip width of the photosensitive member (charged member) 3b and the transfer belt 13b, was formed. As the material of the transfer belt 13b, resistance is controlled by conductive particles such as metal or carbon black, or ionic conductive material, and the volume resistivity is 10%.
A plastic or rubber material having a resistance of ⁸ Ωcm or more can be used. Here, a 150 μm-thick film-shaped member in which carbon black was added to PET to adjust the volume resistivity to 10 ¹³ Ωcm.

By the above-mentioned blade type charger 5b which is a CNT contact type charger, the photosensitive drum 4 is negatively charged,
It is uniformly charged to 00V. Then, the exposure device 6 performs raster exposure based on the image signal. Due to this raster exposure, the charge is lost, the potential of the exposed portion on the photoconductor (charged body) is reduced from -600 V to about -50 V, and an electrostatic latent image is formed. Here, the developing device 7
The toner having negative charge on the developing roller 702 comes into contact with the toner, so that the toner does not adhere to the portion where the charge of the photosensitive member (charged member) 3 remains, and the portion without charge, that is, the exposed portion The toner is attracted to the portion, and a toner image similar to the electrostatic latent image is formed on the photoconductor. The toner image is transferred to the transfer belt 13 which is in contact with the photoreceptor 3 and is driven at a constant speed.
b, the recording material p conveyed by b
The transfer is performed by an electric field formed by supplying charges of the opposite polarity to the toner particles from the blade-shaped charge applying material 61 from which the T protrudes to the transfer belt 13b, and is transferred to a fixing device (not shown) for recording. It is transferred onto the material p.
The blade-shaped charge applying material 61 is in contact with the transfer belt 13b to supply charges. The width of this blade is
Since the width is the same as the width of the nip np, electric charges are supplied only to a region necessary for transfer, unnecessary voltage application is not generated on the entrance side, and "pre-transfer" can be prevented.

In this case, it is considered that the electric charge is not moved by the corona discharge according to the Paschen rule which occurs in the conventional brush or roller type, but is moved by the electric charge injection. In the case of corona discharge, there is a threshold value for the start of discharge in accordance with the gap, the thickness of the facing dielectric material, and the like. In addition, ozone and NOx were not detected, and image deterioration due to “transfer dust” and the like could be reduced. Also, the blade-shaped voltage applying material 61 is brought into contact with the previous transfer belt 13b to apply a voltage of 250 hours, and the resistance becomes 10
It was confirmed that there was almost no change from ¹³ Ωcm. Further, the wear of the transfer belt 13b is significantly reduced as compared with a conventional blade using a resin to which metal or carbon black is added.

Further, the same blade is applied to the belt for about 5
When a voltage was applied with a gap of 0 μm, a slightly higher voltage was required than in the case of contact, but transfer was possible with a voltage sufficiently smaller than that of the conventional roller type, and no image deterioration was observed. In this embodiment, the transfer belt 13b
However, the electric charge may be directly supplied to the transfer body by the transfer blade alone. The numerical values shown above are not limited to these, and supplement the description.

Here, as the carbon nanotube,
Although the multi-walled carbon nanotube 62 is used, a single-walled carbon nanotube may be used. In both cases, the tube has a closed end and an open end. In this example, the closed multi-walled carbon nanotube 62 is used, but an opened tube may be used.

Although polishing is used here as a method for projecting the CNTs, dry etching, ashing,
There is no problem with other methods such as treatment with a chemical solution.

As the resin to be retained, an epoxy resin was used.
T) and polyesters such as poly (butylene terephthalate) (PBT), polyvinyl chloride (PVC), polyvinylidene chloride, polyvinyl alcohol (PVA), polyamide (PA), polypropylene (PP), polystyrene (P
S), resins such as polycarbonate (PC), polyurethane, ethylene-vinyl alcohol copolymer, soft vinyl chloride resin, various thermoplastic elastomers such as styrene-butadiene-styrene block copolymer elastomer, acrylic elastomer, silicone resin, Acetal resins such as polyvinyl butyral, polyvinyl acetate, ethylene-vinyl acetate copolymer and the like can also be used. Examples of the rubber include natural rubber, butadiene rubber, styrene rubber, butadiene-styrene rubber, nitrile-butadiene rubber, ethylene-propylene copolymer rubber, ethylene-propylene-nonconjugated diene copolymer rubber, chloroprene rubber, butyl rubber, and silicone rubber. , Urethane rubber, acrylic rubber and the like are used.

Further, the resistance is controlled not only by the carbon nanotube alone but also by an electron-accepting compound such as metal filler, carbon black and tetracyanoquinodimethane (TCNQ) and an electron-donating compound such as tetrathiafulvalene (TTF). May be used in combination. Here, the example of the photosensitive drum 4 is shown as an image carrier, but an intermediate transfer body may be used. On the contrary, although the recording paper is used as the recording medium, an intermediate transfer member (belt) may be used.

[3-B] Next, an image forming apparatus using the second transfer device 8c will be described as "Example 2 of transfer device". As shown in FIG. 24, the copying machine 1c as the image forming apparatus here is different from the copying machine 1b in FIG. 23 in that the charging device 5b, the exposure device 6, the developing device 7, the cleaning device 11, etc. other than the transfer device 8c Since they are the same, duplicate description is omitted.

First, the production of a roller transfer unit 8c as a transfer device in which CNTs are projected from the surface will be described.
First, the single-walled carbon nanotube 63 is formed by a known technique.
Is prepared. Here, Fe was added to graphite as the anode.
Using a composite rod mixed with a Ni metal catalyst, a graphite rod as a cathode, and 500 Torr He
Single-wall carbon nanotubes were produced by arc discharge in an atmosphere. The synthesized single-walled carbon nanotube 63 was purified using a centrifugal separation method and ultrafiltration.

The substrate 64 of the roller transfer unit 8c is made of Al,
Metals such as SUS and Fe are used. here,
Al was used. EPDM (ethylene prop)
The above single-walled carbon nanotubes 63 are dispersed in a foam (yelene diene rubber) to obtain a resistance value of 1
To form a single-layer structure of the roller of 0 ⁸ Ω. The surface was ground to protrude the CNT. "Example 1 of transfer device"
A toner image is formed on the photosensitive member 3c, which is a member to be charged, on the photosensitive drum 4 in the same manner as described above, and is sent to a nip portion np facing the transfer roller 8c. The recording material p, which is a recording medium, sent from the transport roller 65 is supplied to a transfer roller 8 c having a single-walled carbon nanotube 63 protruding from the surface by a power source 6.
A transfer charge (positive in this case) having a polarity opposite to that of the toner is given by the bias supplied from 6, and is transferred onto the recording material p. The recording material p is sent to a fixing roller 67, which is a fixing device, and is fixed on the recording material p.

In this case as well, transfer could be performed at a lower voltage than in the conventional roller transfer device, ozone and NOx were not detected, and image deterioration due to "transfer dust" could be reduced.
Further, the abrasion of the photoreceptor, which is the image carrier, was small, and the abrasion due to ozone and NOx was also reduced. In this embodiment, the charge is directly supplied to the recording material p. However, the charge may be used as a charge imparting material for a transfer belt also serving as a transport belt. Although the transfer roller 8c has a single-layer structure, the CNT protrudes outward to prevent a pinhole of the photosensitive member (charged member) 3c to form a layer having a higher volume resistivity. A multilayer structure may be used. Note that the numerical values shown above are not limited thereto, and the same supplementary description as in “Example 1 of the transfer apparatus” is applied, but a repeated description is omitted here.

[3-C] Next, an image forming apparatus using the third transfer device 8d will be described as a "third transfer device embodiment". First, multi-walled carbon nanotubes 62 were produced in the same manner as in “Example 1 of transfer device”. The multi-walled carbon nanotubes 62 are dispersed in a nylon resin (dispersion amount: 5 wt%) and melt-spun. The above fiber is sandwiched between urethane pads, a charge is applied to the fiber, and the particle size is 1 μm
Is supplied to draw out the fiber from one side, and the surface is mechanically polished to expose the carbon nanotubes 62 on the fiber surface layer. The urethane pads arranged diagonally were arranged so as to be orthogonal to each other in two steps, so that the carbon nanotubes were exposed on the entire outer periphery of the fiber. One stage or a plurality of stages may be used depending on the load, the drawing speed, and the like.

The conductive fibers exposing the carbon nanotubes 62 were planted on the holding member 67 to form the transfer brush 8d. As shown in FIG. 26, the transfer brush 8
The CNT 62 protrudes from the surface of the fiber 68 of d. Here, the method of dispersing the carbon nanotubes in the resin was used.
The brush may be formed with carbon nanotubes alone by implanting the hair directly on the holding member, which is sufficiently long as m. The transfer brush 8d thus manufactured was used in a color copying machine 1d which is an image forming apparatus of an intermediate transfer system. Here, only the transfer portion of the photosensitive drum 3d as an image carrier and the intermediate transfer belt 69 is shown.

It is desirable that the intermediate transfer belt 69 has a volume resistivity of 10 ¹² Ωcm or more from the viewpoint of holding a toner image and transferring. In this embodiment, the volume resistivity is 1
0 using ¹ of ^{3 Ωcm} thing. As the structure, a belt material having a three-layer structure is used here, but a single layer may be used. The intermediate transfer belt 69 is brought into contact with the photosensitive drum 4, and the transfer brush 8 d from which the charge supply member CNT 62 is projected from the opposite side of the photosensitive body (charged body) 3 is brought into contact with the intermediate transfer belt 69. The transfer is performed by applying a voltage necessary for the transfer.

The color image information divided into black, cyan, magenta, and yellow is used to form a toner image on the photosensitive member (charged member) 3d in the same manner as in the embodiment [3-A], and each is subjected to intermediate transfer. The transfer to the belt 69 forms a superposed toner image of black, cyan, magenta, and yellow. Thereafter, the image is collectively transferred as a color image to a recording material (not shown) as a recording medium by secondary transfer. Compared with the conventional brush transfer, ozone and NOx were not generated, and image deterioration due to image blur and transfer dust was reduced. Further, even when the continuous voltage was applied for 150 hours, the resistivity of the intermediate transfer belt 69 did not decrease.

Here, using the intermediate transfer belt 69,
Although the transfer brush 8d is used as the charge applying material, a transfer voltage may be directly applied to the transfer medium by the transfer brush 8d.
Although the photosensitive drum 3d was used as the image carrier,
An intermediate transfer member for the next transfer may be used. Similarly, the transfer member is an intermediate transfer member (belt) in this case, but may be a recording material as a recording medium. The brush may be a rotating brush in which conductive fibers obtained by projecting CNTs from a rotating body are planted. Note that the numerical values shown above are not limited thereto, and the same supplementary description as in “Example 1 of the transfer apparatus” is applied, but a repeated description is omitted here.

In the above, the electrophotographic copying machine 1 and the color copying machine 1d have been described as image forming apparatuses.
The present invention is not limited to this. The present invention is applied to a facsimile, a printer, or a digital copier which has these functions in combination and digitally processes image information required for a writing process in each of the functions. In these cases, similar effects can be obtained.

[0234]

As described above, according to the first aspect of the present invention, the injection type charging requires a level at which the electrons (holes) are retained, as compared with the charging by discharge. The required number of trap levels was defined for the required charging potential, and a charged body of a material having more than that was prepared. When the number of trap levels is equal to or more than the required number, the charging efficiency of the member to be charged is improved. According to the second aspect of the present invention, n <{4πεkT / q ² * log (σ ′ / σ)} is set so that the trap level is set to such an amount that hopping conduction does not matter.
By manufacturing the member to be charged so as to obtain a trap level satisfying the expression ^3, a decrease in resistance due to hopping can be avoided.

According to the third aspect of the present invention, when V> 0, N
By setting a> CV / q and Nd> CV / q when V <0, sufficient charging can be performed for both positive charging and negative charging. According to the invention of claim 4, the carbon nanotube is very thin due to its shape, has high mechanical strength, has excellent stability as a field emission element member, and is effective as a charger having properties as a solid lubricant. Has available features. For this reason, an image forming apparatus that selectively employs such a charger and the member to be charged according to any one of claims 1 to 3 has the same effect as each charger and each member to be charged as an image forming apparatus. And furthermore, the merchantability of the image forming apparatus can be improved.

According to the fifth aspect of the invention, the same effects as those of the fourth aspect of the invention can be obtained. In addition, since the charging device is of a blade type, the surface of the charging device slides on the surface of the member to be charged. Even if the contact area and the non-contact area are formed by the surface roughness of the charged body, the respective areas are alternately replaced by slipping on the surface, so that uniform charging is possible because the area contacting the body surface is greatly expanded. . According to the sixth aspect of the invention, the same effect as that of the fourth aspect of the invention can be obtained. In addition, by using a roller type charger, cleaning is performed on a portion not in contact with the member to be charged, and the effect is sufficiently achieved. Can be demonstrated. At the same time, the surface of the charger can be polished with a cleaner. By incorporating the polishing step into the charging process, and by rotating the surfaces different from the object to be charged and rotating each other, the effect is the same as that of the blade type. Can be obtained, and the shortage of the contact area, which is a problem in a normal roller charger, can be compensated for, and uneven charging can be eliminated.

According to the seventh aspect of the invention, the same effect as that of the fourth aspect of the invention can be obtained, and further, by using a brush on the surface of the charger, it is possible to prevent the gap from fluctuating largely due to mixing of toner. . Moreover, the manufacturing cost can be reduced by diverting the brush manufacturing method and the like. According to each of the eighth and ninth aspects of the invention, when the carbon nanotube of the charger contacts the pinhole, an overcurrent flows through the carbon nanotube,
The tip of the carbon nanotube generates heat, is oxidized and consumed by oxygen in the air, and is instantaneously separated from the pinhole of the photoconductor. Also, the magnitude of the overcurrent is suppressed by the resistance layer serving as a protection resistor. As a result, the voltage of the DC power supply does not decrease. Therefore, even when there is a pinhole, the photoconductor can be charged uniformly. Claim 1
In the invention of No. 0, since the conductive particles are dispersed in the resistance layer made of the polymer resin, the resistance value can be easily controlled by the dispersion amount of the conductive particles and the thickness of the resistance layer.

According to the eleventh aspect of the present invention, a process for orienting the carbon nanotubes such as electrostatic adsorption or electrophoresis is not required, and the manufacturing cost of the contact type charger can be reduced. Further, since the carbon nanotubes are strongly held by the holding layer, the carbon nanotubes are less likely to be peeled off from the resistance layer while the contact-type charger slides on the member to be charged, and the long-term stability of the charger is improved. According to the twelfth aspect of the present invention, the process of separating and purifying carbon nanotubes is not required, so that the manufacturing cost of the contact-type charger can be reduced. Further, since a relatively long carbon tube can be obtained, the number of conductive contacts increases, and the charge injection speed improves.

According to the thirteenth and fourteenth aspects of the present invention, when the carbon nanotube of the charger contacts the pinhole, an overcurrent flows through the carbon nanotube, the tip of the carbon nanotube generates heat, and is oxidized and consumed by oxygen in the air. However, the carbon nanotube is instantaneously separated from the pinhole of the photoconductor. Also, the magnitude of the overcurrent is suppressed by the resistance layer serving as a protection resistor. As a result, the voltage of the DC power supply does not decrease. Therefore, even when there is a pinhole, the photoconductor can be charged uniformly. Further, since the carbon nanotube is embedded in the resistance layer, the carbon nanotube is strongly held in the resistance layer. As a result, the carbon nanotubes are hardly peeled off from the resistance layer while the contact-type charger slides on the member to be charged, and the long-term stability of the charger is improved.

According to the fifteenth aspect, since the conductive particles are dispersed in the resistive layer made of a polymer resin, the number of carbon nanotubes protruding from the surface of the resistive layer and the resistance value of the resistive layer can be controlled independently. It is easy to optimize the resistance value of the resistance layer. A method according to a sixteenth aspect of the present invention includes a step of forming a resistance layer containing carbon nanotubes on a surface facing a photoreceptor, and a step of polishing the resistance layer so that the tips of the carbon nanotubes protrude from the resistance layer. Therefore, the process of aligning and fixing the carbon nanotubes becomes unnecessary, and the cost reduction of the contact type charger is expected.

According to the seventeenth aspect of the present invention, since the charging device according to the eleventh, twelfth, or sixteenth aspect is mounted, even if the charged body has a pinhole, no uneven charging occurs on the charged body. Image is obtained. Further, when the member to be charged is charged by charge injection, ozone and NOx are not generated. Further, even when the member to be charged is charged by corona discharge, charging can be performed at a lower voltage than that of a conventional contact-type charger, and ozone and NOx can be reduced. According to the eighteenth aspect of the present invention, by using a charge imparting material having carbon nanotubes protruding from the surface, transfer can be performed at a lower voltage, ozone and NOx can be reduced, and image deterioration due to transfer dust and the like can be reduced. Further, since the coefficient of friction of the CNT is small, abrasion of the image carrier and the transfer member facing each other can be suppressed.

According to the nineteenth aspect of the present invention, since a charge imparting material having carbon nanotubes protruding from the surface is used, transfer can be performed at a lower voltage, ozone and NOx are reduced, and image deterioration due to transfer dust is also reduced. it can. Also, CNT
Has a small friction coefficient, it is possible to suppress abrasion of the image carrier and the transfer member facing each other. According to a twentieth aspect of the present invention, the object to be charged according to the first, second, or third aspect is used to improve charging efficiency, and further, by using a charge-imparting material in which carbon nanotubes protrude from the surface, transfer is performed at a lower voltage. Ozone and NOx can be reduced, and image deterioration due to transfer dust and the like can also be reduced. Further, since the coefficient of friction of the CNT is small, it is possible to suppress the wear of the image carrier and the transfer member forming the object to be charged.

According to the twenty-first aspect of the present invention, the use of a charge-imparting material in which carbon nanotubes protrude from the surface allows
Ozone and NOx are reduced, the surface resistance of the transfer belt is not reduced due to aging, and image deterioration due to transfer dust and the like can be reduced. In addition, since the friction coefficient of the CNT is small, the wear of the belt can be suppressed, the life of the belt can be extended, and the maintenance of the product is free and the cost is reduced. According to a twenty-second aspect of the present invention, ozone and NOx are reduced by using a charge-imparting material having carbon nanotubes protruding from the surface, and the surface resistance of the intermediate transfer belt is not reduced due to a change with time. Image degradation can also be reduced. In addition, since the friction coefficient of the CNT is small, the wear of the belt can be suppressed, the life of the belt can be extended, and the maintenance of the product is free and the cost is reduced.

According to a twenty-third aspect of the present invention, by using a blade-like charge imparting material having carbon nanotubes protruding from the surface, transfer can be performed at a low voltage, ozone and NOx are reduced, and image deterioration due to transfer dust is caused. Can also be reduced. Furthermore, since electric charge can be supplied only to a specific area and electric charge is not applied to the nip entrance, pre-transfer can be suppressed, and image deterioration due to transfer dust can be reduced. The invention of claim 24 is
By using a roller-shaped charge imparting material with carbon nanotubes protruding from the surface, transfer can be performed at low voltage, ozone and NOx are reduced, and additional transfer means such as a transfer belt are not required. Image deterioration can be reduced.

According to a twenty-fifth aspect of the present invention, by using a roller-shaped charge imparting material having carbon nanotubes protruding from the surface, transfer can be performed at a low voltage, ozone and NOx can be reduced, and image deterioration due to transfer dust can be prevented. Can be reduced. Further, wear of the opposing members can be reduced.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an image forming apparatus equipped with a member to be charged as one embodiment of the present invention.

FIG. 2 is a schematic configuration diagram of a roller charger used by the image forming apparatus of FIG. 1;

FIG. 3 is a schematic enlarged sectional view of the roller charger of FIG.

FIG. 4 is an equivalent circuit diagram of a pinhole portion in a member to be charged of the roller charger of FIG.

FIG. 5 is an explanatory diagram showing an enlarged cross-sectional configuration of a member to be charged of the roller charger of FIG. 2;

FIG. 6 is a schematic configuration diagram of an image forming apparatus equipped with a brush type charger as another embodiment of the present invention.

FIG. 7 is a functional explanatory view of a modified example of the brush-type charger of FIG. 6;

8 is an overall schematic configuration diagram of the brush-type charger of FIG. 7;

FIG. 9 is a schematic diagram of the brush-type charger of FIG. 7 as viewed from the side.

10 is an overall schematic configuration diagram of another modified example of the brush-type charger of FIG. 6;

FIG. 11 shows a cross-sectional configuration explanatory view of a brush type charger as another embodiment of the present invention.

12A and 12B are explanatory diagrams of the operation of the brush type charger of FIG. 6 and the like, wherein FIG.

FIG. 13 is a sectional view of a main part of a brush-type charger and a member to be charged as another embodiment of the present invention.

14 (a) illustrates a process of manufacturing the brush-type charger of FIG. 13;
It is a figure divided and explained to (d).

FIG. 15 is a view for explaining another manufacturing process of the brush-type charger of FIG. 13 by dividing the process into (a) to (d).

FIG. 16 is a view for explaining another manufacturing process of the brush-type charger of FIG. 13 by dividing it into (a) to (d).

FIG. 17 is a view for explaining another manufacturing process of the brush-type charger of FIG. 13 by dividing the process into (a) to (d).

FIG. 18 is a sectional view of a main part of a brush type charger and a member to be charged as another embodiment of the present invention.

19 (a) illustrates a process of manufacturing the brush-type charger of FIG. 18;
It is a figure divided and explained to (e).

FIG. 20 is a view for explaining another manufacturing process of the brush-type charger of FIG. 18 by dividing it into (a) to (e).

FIG. 21 is a sectional view of a main part of a brush type charger and a member to be charged as another embodiment of the present invention.

FIG. 22 is a view for explaining the manufacturing process of the brush-type charger of FIG. 21 divided into (a) and (b).

FIG. 23 is a schematic configuration diagram of an image forming apparatus equipped with a blade type transfer device as another embodiment of the present invention.

FIG. 24 is a diagram illustrating a roller transfer unit as another embodiment of the present invention and an arrangement configuration of the transfer unit with respect to an image forming apparatus.

FIG. 25 is a schematic configuration diagram of a blade-type transfer device as another embodiment of the present invention.

FIG. 26 is an enlarged cutaway side view of a brush portion of the blade type transfer device of FIG. 25;

FIG. 27 is a schematic configuration diagram of a conventional roller charger.

FIG. 28 is a schematic configuration diagram of another conventional roller charger.

FIG. 29 is a schematic configuration diagram of an image forming apparatus equipped with a conventional transfer device.

FIG. 30 is a schematic configuration diagram of another conventional transfer device.

DESCRIPTION OF SYMBOLS 1, 1a-1c Image forming apparatus 3, 3a-3d Charged body 4 Photoreceptor drum 5, 5a-5f Charger 8, 8a-8d Transfer device q Elementary charge C per unit area of charged body Capacity N Number of trap levels V Desired voltage 24,30 CNT (carbon nanotube)

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Akiyoshi Murakami 1-3-6 Nakamagome, Ota-ku, Tokyo, F-term in Ricoh Co., Ltd. JA26 JB10 MA04 MA06 MA14 MA20 MB04 3J103 AA02 AA14 AA15 AA24 AA33 AA51 AA72 BA41 BA43 BA46 EA02 EA11 EA20 GA02 GA52 HA03 HA04 HA05 HA12 HA15 HA18 HA32 HA37 HA47 HA51 HA52 HA53

Claims (25)

[Claims] In a system for charging by directly or indirectly moving charges from the surface of a charger to the surface of a member to be charged, the number N (1) of trap levels per unit area of the member to be charged has / Cm ² ) satisfying the following conditions. N> CV / q where: C: capacity per unit area of the member to be charged (1 / cm ² ) V: desired voltage q: elementary charge 2. The charged object according to claim 1, wherein the number n of trap levels per unit volume (acceptor: na,
Donor: An object to be charged, wherein nd) satisfies the following conditions. n <{4πεkT / q ² * log (σ ′ / σ)}
³ Here, σ: desired conductivity of the member to be charged in the dark (1 / Ωcm) σ ′: conductivity when there is no trap level k: Boltzmann constant T: temperature (K) ε: dielectric constant n: na, nd Smaller one (pcs / cm ³ ) 3. The trap level according to claim 1, wherein the level for trapping electrons is Nd, and the level for trapping holes is N.
(a) a member to be charged, which satisfies the following conditions: When V> 0 Na> CV / q When V <0 Nd> CV / q 4. An image forming apparatus according to claim 1, 2 or 3, wherein CNTs (carbon nanotubes) are used as a charger. 5. An image forming apparatus, wherein the charger of claim 4 is formed in a blade shape. 6. An image forming apparatus according to claim 4, wherein said charger is formed in a roller shape. 7. An image forming apparatus, wherein the charger of claim 4 is formed in a brush shape. 8. An image forming apparatus having a charger according to claim 4, wherein a resistance layer is provided on a surface facing the member to be charged, and CNTs (carbon nanotubes) are held on the resistance layer. An image forming apparatus comprising: 9. An image forming apparatus having the charging device according to claim 4.
The resistance value of the resistance layer is 10 ⁴-10⁸Is Ω
An image forming apparatus comprising: 10. An image forming apparatus having the charger according to claim 8, wherein the resistance layer is made of a polymer resin in which conductive particles are dispersed. 11. The method for manufacturing a charger according to claim 8, 9 or 10, wherein a step of forming a holding layer made of a polymer resin containing carbon nanotubes on the resistance layer, and polishing the holding layer. And causing the tips of the carbon nanotubes to protrude from the holding layer. 12. The method for manufacturing a charger according to claim 8, wherein at least Fe, Co, and N are formed on the resistance layer.
forming a catalyst layer made of a metal, alloy, or compound containing one of the above-mentioned i. and a chemical vapor using at least one of a hydrocarbon gas such as acetylene, ethylene and methane on the catalyst layer. A method for producing a charger, comprising a step of forming carbon nanotubes by a phase growth method. 13. An image forming apparatus having a charger according to claim 4, further comprising a resistance layer on a surface facing said member to be charged.
An image forming apparatus, wherein the tip of the carbon nanotube held in the resistance layer protrudes from the resistance layer. 14. An image forming apparatus having the charger according to claim 13, wherein the resistance value of the resistance layer is 10 ⁴ to 10.
An image forming apparatus having a resistance of ⁸ Ω. 15. An image forming apparatus having the charger according to claim 13 or 14, wherein the resistive layer is made of a polymer resin in which conductive particles are dispersed. 16. The method for manufacturing a charger according to claim 13, 14 or 15, wherein a step of forming a resistance layer containing the carbon nanotubes on a surface opposing a member to be charged, and polishing the resistance layer. A method for manufacturing a charger, comprising a step of projecting a tip of a carbon nanotube from a resistance layer. 17. An image forming apparatus equipped with the charger of claim 11, 12, or 16. 18. An image forming apparatus for forming an image by transferring a toner image formed on an image carrier made of a member to be charged to a recording material arranged close to or in contact with a predetermined transfer nip area. An image forming apparatus, wherein a charge imparting material having CNTs (carbon nanotubes) protruding from the surface is used for a transfer device. 19. An image forming apparatus for forming an image by transferring a toner image formed on an image carrier formed of a member to be charged to a recording material arranged close to or in contact with a predetermined transfer nip area. An image forming method, wherein a charge imparting material having CNTs (carbon nanotubes) protruding from the surface is used for a transfer device. 20. An image forming apparatus wherein the member to be charged according to claim 19 is the member to be charged according to claim 1, 2 or 3. 21. An image forming apparatus according to claim 18, wherein said transfer device is a belt which also serves to convey a recording material. 22. The image forming apparatus according to claim 18, wherein said recording material or image carrier is an intermediate transfer member. 23. The image forming apparatus according to claim 8, wherein said charge-providing material has a blade shape. 24. The image forming apparatus according to claim 8, wherein said charge-providing material has a roller shape. 25. An image forming apparatus according to claim 8, wherein said charge-providing material has a brush shape.