JP2002268328A - Charger, charging method, and imaging device using them - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a charger which extends life time of a CNT. SOLUTION: With respect to a charger 1, carbon nanotubes 4 are held on its charger surface 2a facing a body 3 to be charged, and the body 3 is charged through electric field emission, and the current quantity flowing to each of carbon nanotubes 4 is <=10<-12> A, and a density C1 (the number of tubes per cm<2> ) and a resistance Rb of carbon nanotubes 4 satisfy the condition C1×Rb> Va/10<-12> , where Va is the difference (V) of potential by charging applied to the body to be charged and Rb is the total resistance value (Ωcm<2> ) applied to a circuit of charging per unit area to be charged.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a charger for an image forming apparatus such as a copying machine, a facsimile, a printer, and the like, a charging method thereof, and an image forming apparatus using the same.

[0002]

2. Description of the Related Art An image forming apparatus such as a facsimile or a printer uses a charger. As the charging device, a device using carbon nanotubes (CNT) is being used because of its merits such as ozonelessness and low hazard.

[0003] For example, Japanese Patent No. 9902937 discloses a charger using carbon nanotubes (CNT). A brush type is disclosed as the shape of the charger main body of this charger, and a charge injection type is disclosed as a discharge method, and the superiority of the CNT with respect to charge injection is also described.

[0004]

However, many problems still remain in the charger using this CNT. (1) Lifetime It is known that the function of a conventional charger using CNTs rapidly deteriorates when a voltage is applied in the atmosphere. This is thought to be due to the fact that CNTs are degraded due to field emission in the atmosphere. If the life is short, the function as a charger cannot be performed. (2) Charging Unevenness It is known that in DC voltage driving, charging unevenness occurs due to non-uniformity of a gap between an object to be charged and a charger. In particular, by using pulse driving, uneven charging is increased. This is because there is a time zone where no voltage is applied due to the pulse,
This is because it is expected that uneven charging is likely to occur. Uneven charging reduces image quality.

[0005] In addition, there has been a report on the field emission of CNTs into the atmosphere (Japan Hard Copy 97 Proceedings P221). here,
It is described that a single CNT is destroyed at a current value of 10 ⁻¹² A and a voltage value of about 300 V.

SUMMARY OF THE INVENTION An object of the present invention is to provide a charger, a charging method, and an image forming apparatus using the same, which can extend the life and reduce the uneven charging.

[0007]

According to a first aspect of the present invention, there is provided a charger, wherein a carbon nanotube is held on a surface of a charger facing a member to be charged, and is charged via electric field emission. The amount of current flowing per ^tube is 10 ⁻¹² A or less, and the density C1 (lines / cm ² ) and the resistance Rb of the carbon nanotube satisfy the following conditions. C1 × Rb> Va / 10 ⁻¹² Va: charging potential difference applied to the member to be charged (V) Rb: total resistance value (Ωcm ² ) applied to the charging circuit per unit area to be charged according to the invention according to claim 1. For example, it is possible to prevent the CNT from deteriorating and improve the reliability and stability of the charger.

According to a second aspect of the present invention, in the charging device of the first aspect, the voltage is gradually increased with respect to the member to be charged.

According to the second aspect of the present invention, even when the resistance and the density cannot be completely limited, deterioration of the CNTs can be prevented, and the reliability and stability of the charger can be improved.

According to a third aspect of the present invention, in the charger of the first or second aspect, the shape of the charger main body is a blade type or a brush type.

According to a fourth aspect of the present invention, there is provided the charger according to the first or second aspect, further comprising a polishing member for polishing a surface of the charger main body.

According to a fifth aspect of the present invention, in the charger of the fourth aspect, the shape of the charger main body is a roller type.

According to the fourth and fifth aspects of the present invention, it is possible to constantly expose clean CNTs with little deterioration on the surface of the charger, so that the reliability and stability of the charger are further improved.

According to a sixth aspect of the present invention, there is provided an image forming apparatus using the charging device according to any one of the first to fifth aspects.

According to the image forming apparatus of the sixth aspect,
It is a charging system that does not damage the photoreceptor, can reduce costs, and can provide an image forming apparatus equipped with a long-life and highly reliable charger that generates very little ozone and NOx.

According to a seventh aspect of the present invention, there is provided an image forming apparatus for forming an electrostatic latent image by directly applying a voltage to an object to be charged by using a charger provided with the carbon nanotube according to the first aspect. Features.

According to the image forming apparatus of the present invention,
Deterioration of the photoreceptor, which is the main element determining the life of the image forming apparatus, can be avoided, and the life of the image forming apparatus can be extended by directly forming an electrostatic latent image without using the photoreceptor. be able to.

[0018] In the charging method of the charging device according to the present invention, the carbon nanotube is held on the surface of the charging device facing the member to be charged, is charged via field emission, and the amount of current flowing per carbon nanotube. There is less 10 ^-12 a, and wherein the density of the carbon nanotubes C1 (present / cm ²⁾ and the resistor Rb is to be applied under the following condition is satisfied conditions, the driving voltage in pulses I do. C1 × Rb> Va / 10 ⁻¹² Va: potential difference (applied voltage) applied to the member to be charged (V) Rb: total resistance value (Ωcm ² ) applied to the charging circuit per unit area to be charged. The reason for adopting the configuration of the present invention will be described below.

In a charger in which only the resistance and the density are specified,
At the same time, it is assumed that a voltage is applied to CNTs in all areas and a current flows through all the CNTs at the same time, and the resistance value and the density are set.

If no voltage is applied at the same time, a large current flows through the few CNTs to which the voltage is applied, and the CNTs are destroyed. The reason will be described with reference to FIG.

When the density C1 of the CNT and the resistance value Rb are set, as shown in FIG. 10A, CNT (1) -CNT (10)
It is assumed that current flows evenly through each CNT.

However, there is a case where a voltage is actually applied only to CNT (1) -CNT (3) as shown in FIG. This occurs, for example, when the member to be charged is charged.

In particular, when a voltage is applied by DC, a voltage is always applied, and a current flows only when the CNT of the charger moves to an uncharged area.

In such a case, the CN shown in FIG.
As in the case of T (1) -CNT (3), the leading end of the member to be charged in the moving direction is in such a state, and a large current flows and CN
T destroys.

In a normal charger, the member to be charged moves continuously. The surface of the uncharged object continuously enters the voltage application area. No voltage is applied to all CNTs at the same time.

Therefore, by making the driving method pulse-shaped, it is possible to form a state in which a voltage is simultaneously applied. This is an image in which the voltage is separately applied to each one of the CNTs, and the "synchronization" of the voltage application is adjusted.

That is, when the continuously moving charged body moves to some extent, a pulse voltage is applied,
Apply voltage to CNT at the same time. by this,
An average current flows through all the CNTs without applying a voltage to only a few of them. This makes it possible to create the state assumed when setting the above equation. CN
It is possible to prevent the deterioration of T.

At the same time, a cooling time can be created by pulse driving, and there is also an effect of suppressing heat generation.

According to a ninth aspect of the present invention, there is provided a charging method for a charging device, wherein charging is performed with a drive waveform in which the rising of a pulse is inclined.

The reason for adopting the configuration of the ninth aspect of the present invention will be described below.

The causes of the deterioration of the CNT due to the application of voltage include heat generation due to energization and oxidation. As a method of preventing this, there is a method of reducing a current value or a voltage value.

It is known that a CNT is destroyed when a voltage of 300 V is applied thereto, as described in the prior art. Therefore, a device is devised so that the potential difference between the member to be charged and the charger is always small. As a method, as shown in FIG.
Is provided with a slope P1 at the rising edge of the pulse. With this waveform, the potential difference between the charged object and the charger can be reduced at the initial rising point (a). When the voltage is gradually increased, field emission is performed from the CNT as shown by a point (b), and the charged body increases the charged potential.

That is, the point (c) is maintained while the potential difference between the charger and the member to be charged is kept constant (see the two-dot chain line P2).
The end of the pulse can be reached as shown by. During this period, a large potential difference is not formed, and a large current value that would destroy the CNT does not flow. Thus, the driving waveform P
By making the inclination of the CNT, the potential difference between the charger and the member to be charged can be kept constant, and the deterioration of the CNT can be suppressed.

The charging method of the charging device according to the tenth aspect is characterized in that:
The inclination of the driving waveform satisfies the following expression. ^{K <C1 × 10 -12 / Ca} Ca: unit volume per area ^{(C / cm 2) K =} dVa / dt of the member to be charged: In the invention described in claim 9 (voltage increase rate per unit time) inclined The rise of the pulse was inclined to provide a drive waveform that did not produce a large potential difference. However, if the slope is steep, a large current flows, and the CNT deteriorates. Therefore, it is necessary to define this inclination so that the CNT is not broken. The relationship between the current flowing through the CNT and the slope P1 will be examined below.

The charge amount Q (V
a) (C / cm ² ) depends on the potential difference of the surface potential Vs of the member to be charged. This when resemble the a member to be charged capacity Ca (F / cm ^2), can be written as Q (Va) = Ca × Vs .

When the voltage Vs increases by a certain amount, the required charge also increases accordingly. The amount of charge increase is ΔQa (V
s) and the amount of increase potential is written as ΔVs, it can be written as ΔQa (Vs) = Ca × ΔVs... (a).

Here, assuming that the amount of increased potential is increased with respect to time, the amount of increase K can be expressed as K = ΔVs / Δt = dVs / dt (b).

As can be seen from FIG. 11, the surface Vs is obtained by subtracting the threshold voltage Vth from the applied voltage Va. Vs = Va−Vth This is substituted into the above equation. Then, when both sides are divided by Δt, ΔQa (Va−Vth) / Δt = Ca × Δ (Va−Vth) / Δt (c) dQa (Va) / dt = Ca × dVa / dt = Ca × K ... (D) (Here, since Vth is constant, it is eliminated by differentiation.) Since the charge increase dQa (Va) / dt for a certain time is a current, Ia = dQa (Va) / dt・… (E) can be written.

[0039] However Ia (A / cm ²⁾ was the value of the current flowing through a unit area. Assuming that the number of CNTs per unit area is C1, the current value flowing through each one of the CNTs can be expressed as Iaa = Iaa = Ia / C1... (F).

[0040] Here, the deterioration condition of the CNT for each one CNT, since it destroys the flow 10 ^-12 A or more are known, it is necessary to suppress the less. Iaa <10 ⁻¹² A... (D) Substitute the expression (f) to eliminate Iaa. Iaa = Ia / C1 <10 ⁻¹² (h) The equation of (e) is substituted to eliminate Ia. dQa (Va) / dt / C1 <10 ^-12 ... (i) Substituting equation (d), dQa (Va) / dt is deleted. Ca × dVa / dt / C1 = Ca × K / C1 <10 ⁻¹² ... (J) Therefore, K <C1 × 10 ⁻¹² / Ca... (K) By satisfying this expression, the CNT is deteriorated. No current flows.

The charging method of the charging device according to the eleventh aspect is characterized in that:
The pulse interval satisfies the following condition. T1 <10 ⁻⁵ / S1 S1: relative speed of the charger to the member to be charged (m / sec) T1: pulse interval (sec) When charging is performed by a pulse, charging unevenness appears. This uneven charging is caused by a mixture of charged portions and uncharged portions. It is necessary to reduce the pulse interval so that a portion that is not charged does not appear.
The field emission distance of the CNT is 10 μm. This has been confirmed experimentally. The experimental results are shown in FIG.
In FIG. 12, the horizontal axis indicates the distance between the charger and the member to be charged.

The vertical axis shows the charging potential at an applied voltage E of -500 V. It can be seen from FIG. 12 that when the distance is 10 μm or more, charging due to field emission does not occur. For this reason, the area within 10 μm from the CNT is a chargeable area. In a circle having a radius of 10 μm with one pulse voltage, charging is completed.

Next, a pulse voltage is required when the member to be charged moves by 10 μm. In accordance with this, the pulse voltage of the above equation may be applied.

Here, 10 ⁻⁵ indicates 10 μm, and 10 ^−5.
/ S1 is the time required for the member to be charged to move by 10 μm. In other words, the next pulse may be applied before moving by 10 μm, which can be defined as the pulse interval. That is, by satisfying the above expression, the object to be charged is 10 μm
This means that a pulse can be applied each time the robot moves.

By satisfying this condition, the pulse interval is sufficiently short and there is no uncharged area. Therefore, there is no uneven charging.

According to a twelfth aspect of the present invention, there is provided a method for charging a charger,
The peak value of the pulse is suppressed to a discharge starting voltage or less.

A voltage is applied to the charger in a pulsed manner.
The object to be charged is charged by this pulse, and the charged potential is determined by the pulse voltage. This can be understood from the graph of Va / Vs (applied voltage / surface potential) of the CNT charger as shown in FIG.

This graph shows the characteristics of the CNT charger. In the negative side, charging occurs at a low threshold value due to field emission. On the other hand, on the positive side, no field emission occurs,
The voltage at which discharge occurs becomes the threshold. The threshold is about 600V. This time, the member to be charged is negatively charged.

For example, when a voltage of -500 V is applied, -300 V
Charge to some degree. When the object to be charged is charged at -300 V and no pulse voltage is applied to the charger, there is a potential difference of 300 V between the object to be charged and the charger. At this time, since the discharge starting voltage is 600 V according to FIG. 13, no discharge occurs.

Conversely, if the charging voltage is set to -1000 V, for example, when the pulse voltage becomes 0 V, the voltage difference between the charged object and the charger becomes 800 V, and discharge occurs. This discharge occurs in places, which has a great influence on the charge uniformity.

[0051]

(Embodiment 1) (Embodiment 1) A schematic diagram of a charger 1 is shown in FIG. Charger 1
And the member to be charged 3 face each other in parallel via a uniform gap G. The gap G is kept at about 10 microns. The CNT 4 is held on the surface of the charger 1.

Hereinafter, a detailed configuration including a method of making the same will be described.

The charger 1 comprises a substrate 2, which is a plate made of SUS and has a thickness of about 10 mm. The surface 2a of the substrate 2 is ground in accordance with the curvature of the member 3 to be charged. The substrate 2 is conductive, and a wiring 5 ′ is provided from an end thereof, so that a voltage E is applied to the substrate 2.

The CNT 4 is held on the surface 2a of the substrate (SUS plate) 2. CNT4 is synthesized by CVD (chemical vapor deposition). According to the synthesis by CVD, a CNT4 having a length of more than 10 μm can be formed, and this time, the length was set to about 5 μm. CVD
By synthesizing the CNTs 4 in the above, it is possible to increase the density. This time was 100 / μm ² (10 ⁸ this / cm ^2).

The charger 1 has an external resistor (10 ⁵ Ωcm ² ) R
b was provided. The relationship between the density C1 of the CNT 4 and the external resistance Rb satisfied the following conditions. C1 × Rb> Va / 10 ^−12, that is, 10 ⁸ × 10 ⁵ > 300/10 ⁻¹² .

An operation test was conducted with the applied voltage E set to Va = 300 V. As a result, it was confirmed that the operation of A4 size, 50 × 1000 sheets was possible. (Comparative Example 1) The shape and the manufacturing method of the charger 1 were all the same as those in Example 1.
The same as above. Here, the external resistance Rb was changed as the total resistance of the charger 1. The value of the external resistance Rb in Example 1 was 10 ⁵ Ω, but was set to 10 ³ Ω this time. Then, when an operation test was performed under these conditions, the charging potential of the charger 1 was reduced by half in about one hour of continuous operation. (Embodiment 2) FIG. 2 shows a case where the shape of the charger 1 is a roller type. Although the surface of the charger 1 is in contact with the member 3 to be charged in some places, most of the surface is non-contact, and field emission occurs in the non-contact part. Further, a cleaner may be provided, and by selectively polishing a resin other than CNT4, fresh CNT4 can be constantly projected on the surface. Hereinafter, the details will be described.

The charger 1 is of a roller type and has a CN
Equipped with T4. That is, as shown in FIG. 3, the voltage applying device (charging device) is a roller, and has a function of applying the voltage E to the member 3 to be charged. The charger 1 has a laminated structure of a conductive cylindrical substrate 5, a conductive elastic body 6, and a medium resistance layer 7 containing CNT 4 as a surface layer.

The cylindrical substrate 5 is preferably formed of a metal conductor made of aluminum, SUS, Fe, or the like, or a conductor film formed on the surface of an insulator made of acrylic resin or plastic. If the volume resistance is 10 ⁻² Ωcm or less, resins and rubbers containing various conductive agents can be used.

In this case, aluminum was used because of the manufacturing cost of the manufacturing process. After processing aluminum into a cylindrical shape with a thickness of 20mmΦ and a thickness of 2mm, to improve the adhesion of the surface,
Use a grinder to give a roughness of 0.1 mm order. A conductive elastic body 6 having a thickness of 5 mm as shown in FIG.

The conductive elastic body 6 is obtained by dispersing conductive particles in a base material having elasticity. As the base material, 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 preferable. Nylon 6, Nylon 6,6
, Nylon 6-nylon 6,6 copolymer, nylon 6,6
Polyamides, copolyamides or modified products thereof such as nylon 6,10 copolymers, alkoxymethylated nylons such as methoxymethylated nylons, silicone resins, acetal resins such as polyvinyl butyral, polyvinyl acetate, ethylene-vinyl acetate Copolymers, ionomers and the like can also be used.

As the rubber, 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 ,silicone rubber,
Urethane rubber, acrylic rubber and the like are preferred. This time, we adopted silicone resin.

As the 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. Alternatively, non-ionic, anionic, cationic, amphoteric or other organic conductive agents, or organic tin-based conductive agents can also 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. This time, conductive carbon black was used.

The conductive particle carbon black is dispersed in a heat-melted base silicone resin, which is molded and cooled to obtain a solid having a desired shape. The conductivity of the material obtained in this manner can be appropriately adjusted depending on the material ratio. This time, the resistance was adjusted to about 10Ωcm.

The CNT is formed on the conductive surface thus formed.
Is formed as a single layer, and a projection is formed on the surface. As the medium resistance layer 7 provided on the conductive elastic body 6, 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 other than these, a fluorine-based resin or rubber such as polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), Fluoroethylene-hexafluoropropylene copolymer (PTFE
• 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. Therefore, there is a great merit in terms of the life of the photosensitive member or the roller type charger 1 as the member to be charged 3. This time, PVDF was adopted. The mechanical strength of the PVDF is adjusted to be smaller than that of the member 3 to be charged. The resistance value of the middle resistance layer 7 is 10 to 10 ¹¹ Ωc
m, especially 10 ⁷ to 10 ⁸ Ωcm. The resin contains CNT4. Since the CNT 4 also acts as a filler, the resistance was controlled by the CNT 4 and carbon black. The desired resistance value of 10 ⁸ Ωcm was obtained when the concentration of CNT 4 was about 10 wt% and carbon black was about 5 wt%.

The CNT 4 is formed by an arc discharge method, a CVD method, a laser ablation method, or the like. In this case, CNT4 prepared by the arc discharge method was used (multi-walled carbon nanotube (BU201, manufactured by Bucky USA)).
Is in the form of powder similar to carbon black, and this is similarly mixed into a resin and stirred. Thereafter, a film having a thickness of 1 mm was formed on the surface of the low-resistance silicone roller by the dipping method.

Next, the CNT4 thus dispersed in the resin
Is exposed from the surface. Ashing methods, polishing methods, and the like have been devised as such methods. This time, the method by polishing was selected. For polishing, abrasive particles of silica were used. Polishing is performed so that the surface roughness of the resin is on the order of microns. Thereby, the CNT 4 is exposed and protrudes with a length of about 1 micron. The protrusion density of CNT4 is
It was confirmed that the amount was about 1 line / μm ² depending on the amount dispersed in the resin. Further, by setting the surface roughness of the resin to the order of microns, a gap region between the resin and the charged member 3 can be formed stably. In this gap G, non-contact charging is performed.

The cleaner 8 is installed in contact with the roller type charger 1, and the cleaner 8 is used for polishing the charger 1. This cleaner 8 is intended to constantly polish the surface of the charger 1, maintain the surface 2a at an appropriate roughness (rough surface), and project undegraded CNTs 4 from the surface 2a.

Therefore, the above-mentioned polishing step can be performed by the cleaner 8. The cleaner 8 is made of a member having high mechanical strength and capable of always maintaining an appropriate projection state. Suitable materials include metals or alloys such as Al, SUS and Fe, resins having high mechanical strength such as acryl and epoxy, and inorganic substances such as silica, glass and other oxides.

This time, SUS was used. The cleaner 8 is also in the form of a roller, and can be removed when the resin of the charger 1 adheres to the SUS surface. The surface of SUS is provided with roughness on the order of microns (rough surface).
The surface 2a of the charger 1 is polished by rotating the roller-shaped cleaner 8 made of S in contact with the roller-type charger 1 at a different rotation speed. By adjusting the pressing pressure of the charger 2 to the cleaner 2, the amount of shaving of the surface 2a of the charger 1 can be controlled. Since the thickness of the medium resistance layer 7 is about 1 mm, about 500 × 1000 sheets In order to have a long life, the amount of shaving was adjusted to be about 1 nm / rotation.

A photosensitive member was used as the member 3 to be charged. As shown in FIG. 4, the charged body 3 is composed of a surface protective layer 9, a charge transport layer 10, a charge generating layer 11, an undercoat layer 12, and a cylindrical substrate 13 from the surface. Use a strong one. As a material, commercially available resins such as polyester, polycarbonate, polyurethane, acrylic, epoxy, silicone, alkyd, and vinyl chloride-vinyl acetate copolymer can be used.

Further, as a result of studying to improve strength and dispersibility, conductive particles were dispersed in a photocurable acrylic monomer having three or more acryloyl groups in one molecule, and this was exposed to light. By using the surface protective layer 9 formed by coating and photo-curing on the photosensitive layer of the body, the film strength was dramatically improved.

For the charge transport layer 10, 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 thickness of the charge transport layer 10 was about 20 microns, and was formed by dipping coating.

The charge generation layer 11 has a long wavelength (780 nm) which has been conventionally used for digital. CG
M (charge carrier generation material)
Examples of the material include a squarylium dye, a metal-free phthalocyanine dye, a metal phthalocyanine dye, an azulenium salt dye, a thiapyrylium salt, a polycyclic quinone dye, a perylene dye, an azo pigment dye, and an azo pigment. These were put into a binder material such as polyvinyl butyral resin. The charge generation layer 11 was formed by spray coating with a thickness of about 1 to 10 μm.

The undercoat layer 12 improves the chargeability of the photoreceptor,
Further, the photosensitive layer (charge generation layer 11) for the cylindrical substrate 13
The purpose of the present invention is to improve the adhesiveness and applicability of the rubber.

The material used for the undercoat layer 12 is, for example, polyethylene, polystyrene, acrylic resin, vinyl chloride resin, vinyl acetate resin,
Resins such as polyurethane, epoxy resin, polyester, melanin resin, silicone resin, polyvinyl butyral, and polyimide, and copolymers thereof, and the like can be given.

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.

It is preferable that the cylindrical substrate 13 has characteristics such as conductivity, high mechanical strength, low production cost, and good film adhesion. Therefore, a general metal is used, for example, Al, SUS, Fe, Ni, Cu, Mg, Ag, etc.
This time, Al was used. Alternatively, a metal film can be formed on an insulating material such as acrylic to be used as a substitute.

A method of driving an image forming apparatus using the roller type charger 1 will be described below.

The driving method is in accordance with a normal roller type charger. The voltage E is DC, and the applied voltage E is Va = −300 V
And 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 member to be charged (photoconductor) 3 is 60 cpm
Designed to be compatible with

In this embodiment, satisfactory charging ability was obtained even at this speed. As described above, the density C1 of CNT4
Was defined as 1 line / μm ² . In addition, uniformity is high by sufficiently dispersing the resin. Resistance value in this state has become a 10 ⁸ Ωcm. By considering the thickness (1 mm), the resistance value Rb per unit area (1 cm ²⁾ has a Rb = 10 ^8/10 (thickness) = 10 ⁷ Ωcm ^2.

That is, 10 ⁻¹² > I / c1 = V / (c
1 × Rb) = 300 / (10 ⁸ × 10 ⁶ ) = 3 × 10 ⁻¹³ (C1 = 10 ⁸ lines / cm ² , Va = 300) Under these conditions, the life of the charger 1 was 50 × 1000 A4 plates, and it was confirmed that the charger 1 was sufficiently driven.

In FIG. 2, reference numeral 14 denotes recording paper;
15 is a transfer device, 16 is a developing device, 17 is a fixing device, 1
Reference numeral 8 denotes a static eliminator. Comparative Example 2 Shapes of Charger 1, Charged Member 3, and Cleaner 8
The state and the preparation method are all the same as in the second embodiment. Different in creation
The point is that the concentration of CNT4 was changed. CNT4 concentration
2 wt% with respect to epoxy, and the resistance value Rb is CB (Carbo
Control) so that it is the same as in the second embodiment.
Rolled. This allows you to observe the surface after polishing
As a result, the CNT density was 0.01 lines / μm^TwoIt became. This
In the condition of, 10^-12 > I / c1 = V / (c1 × Rb) = 300 / (1
0⁶× 10⁶) = 3 × 10 ^-11 It has become. When the charging was evaluated using this,
It was found that the charging potential decreased with time. this
Was clear even when compared with Example 3 described later. (Embodiment 3) Here, a blade type is adopted for the charger 1.
Used. In the case of the blade type charger 1, its end is covered.
It comes into contact with the charged body 3. I think they are in macro contact
However, microscopically, there are many contact areas.
In this region, field emission occurs. That is, the first embodiment
The fine gap G is unnecessary as described in
The strike can be reduced. The nip is designed to be 2mm,
The resistance value, thickness, surface roughness, etc. are also the same as in Example 2.
And As with the roller type charger 1, the blade table
The surface was processed so that CNT4 protruded. Density C of CNT4
1. The resistance value Rb of the charger 1 is the same as in the second embodiment.
Similar results were obtained in the crop test. (Embodiment 4) Here, the charger 1 is used only for charging the photosensitive member.
Instead, it was adopted for the transfer process. In the transfer process
The image developed on the photoconductor is moved onto the recording paper 13 and
You. At this time, the toner is charged on the back surface of the recording paper 13.
Charge of the opposite polarity. Conventional corona belt
The charging area can be made smaller compared to electric appliances.
You. In this case, the nip is 2 mm, and
The blade was shaped so that pressure was not applied. for that reason,
Image formation with less blurring without toner scattering
Came. (Embodiment 5) FIG. 5 shows a brush type charger 1.
The charger 1 is composed of a base 2, a support fine wire 2B and a fine wire (CNT4).
It has become. The structure and manufacturing method of these basic elements are described in detail above.
He said the details.

The substrate 2 is cast into a mold and molded as in a normal case of a copying machine or the like. The resin material
Recycling was made possible using ABS (acrylonitrile-bradiene styrene copolymer). The shape of the substrate 2 was such that the molding surface of the fixed layer 2A was 300 × 10 mm, and a shape such as a pillar was added to the back surface to enhance the mechanical strength. Thereby, the thickness can be suppressed to about 10 mm.

The fixed layer 2A is formed on the base 2 made of resin. The fixed layer 2A has a thickness of about 500 μm and is applied by a coater. For the fixing layer 2A, the above-mentioned nylon resin was used. The nylon resin used this time has a low melting point and melts at about 100 ° C. TCN for nylon
Q and TTF are doped respectively, and the bulk resistance is 1
It was adjusted to about 02Ωcm. The roughness of the coated surface is 50μ
The resin of the substrate 2 and the conditions for application were selected so as to obtain the m level. Nylon coated in this way has an atmosphere of 10
At 0 ° C., the molten state is sufficiently maintained. Here, a hot plate is installed on the back of the base 2 and the resin of the base 2 is
Heat at 130 ° C. The atmosphere is maintained at about 80 ° C and the fixed layer 2
The surface of A increases in viscosity, but is almost in a state of being hardened. In such a semi-molten nylon film,
Flocking individually made nylon fibers. Nylon fibers to be planted are 10 μm in diameter and 2 mm in length.

The resistance value of one nylon fiber is 3 × 10
It is specified as 3Ω. As a result, the supporting fine wire 2B becomes 120
Assuming that the charger 1 has a density of 1 / mm 2, the charger 1 is expected to have a resistance of 1 × 10 9 Ω. This can be adjusted by the doping amount of TCNQ and TTF as before.
Further, it was confirmed that the fixing layer 2A and the nylon fiber as the supporting fine wire 2B could make ohmic contact and had almost no contact resistance. This is an advantage of using the same type of material. Hair transplantation adopted a method by static electricity. After flocking, the nylon is hardened by removing it from the hot plate and cooling at room temperature to become a solid. At this time, the supporting fine wire 2B is fixed to the fixing layer 2A without melting and keeping the initial shape. Fixed layer 2A and supporting fine wire 2
Although it is conceivable that the interface B is slightly melted, it can be firmly fixed without any problem in the electric resistance.

At this time, the density at which the hairs are planted is specified to be 120 fibers / mm 2. The tips of the implanted support fine wires 2B are aligned to be uniform. To align, slowly contact the metal surface heated to about 120 ° C, and use a longer supporting fine wire 2B than the other.
Only by melting and deforming, the length becomes uniform. The support fine wire 2B planted by this is 0.1 mm
It has a uniform length with a little variation.

With the support wire 2B thus formed, the electric conductivity and the contact resistance are measured. In this condition, the IV curve or CV
Perform the measurement. Thereby, the electric resistance of the supporting fine wire 2B can be measured. This time resistance is 300 × 10
It was 1 × 109Ω in mm square. This condition can be controlled by changing the value by changing the doping amount of the supporting fine wire 2B and the like.

This is brought into contact with the member to be charged (photosensitive member) 3, a voltage E is applied between the member to be charged (photosensitive member) 3 and the charger 1, and the surface potential, the applied voltage and its time constant are evaluated. I do. Thereby, the support fine wire 2B and the member to be charged (photoreceptor)
3 can be evaluated. The contact resistance obtained this time is 1 × 10 10 Ω.

The carbon nanotubes (fine wires) 4 are implanted in the supporting fine wires 2B thus formed. This time, as the flocking method, electrophoresis and immobilization with an epoxy resin were adopted. This method has an advantage that the carbon nanotubes 4 can be arranged by Coulomb force. The epoxy resin has conductivity, is cured at about 90 ° C., and has elasticity.

The carbon nanotube 4 has an arc discharge,
Multilayer type by CVD method, length is 100 ~ 150μm,
The diameter was adjusted to 10 to 25 nm. The carbon nanotubes 4 were classified by centrifugation, and those having substantially the same shape were selected.

An epoxy resin is applied to the supporting fine wire 2B fixed to the fixing layer 2A. The epoxy wets the supporting wire 2B because of its low viscosity in this mode. In addition, since this epoxy is made conductive, the supporting fine wire 2B can be used as an electrode.

About 5 wt% of carbon nanotubes 4 are IPA
(Iropropyl alcohol), 300x15m
m, placed in a 2.1 mm deep container. The bottom of the container is made of conductive metal and has electrodes from the back.
The support fine wire 2B coated with the epoxy prepared above is put on the container. Since the length of the supporting fine wire 2B is uniform to 2 mm, it does not come into contact with the lower electrode.

In this state, a voltage E is applied to bring the carbon nanotubes 4 into contact with the supporting fine wires 2B by electrophoresis. Take enough time to actually move and be in contact with IPA
Is heated and evaporated, and the epoxy is cured by baking. The density C1 of the carbon nanotubes 4 can be controlled by the concentration in the IPA dispersion, the application time and the applied voltage.
As a result, the density C1 of the CNT 4 became about 1 / μm ² . Under these conditions the resistance value Rb is previously 10 ⁹ Omega. The support brush 2B and the carbon nanotubes 4 form a charging brush.

This brush-type charger 1 is set to Va = −300
A DC power source E of V. The charge transport layer 10, the charge generation layer 11, the undercoating layer (hole injection blocking layer) 12, and an object to be charged (photoconductor OPC) 3 composed of an Al substrate 13 are brought into contact with each other. Charging was performed. The peripheral speed of the photoreceptor is 300 mm / s
Therefore, the contact time between the brush charger 1 and the member to be charged (photoconductor) 3 is 0.1 s.

The photosensitive member was charged to -280 V while it was in contact with the brush type charger 1, and it was confirmed that the charging brush in which the carbon nanotubes 4 were connected to the conductive fibers had sufficient charging ability. Further, the variation of the charging voltage in the longitudinal direction of the photoreceptor was within 5%, and sufficient uniformity was obtained. In addition, the service life was satisfied with 50 × 1000 sheets. (Embodiment 6) FIG. 6 shows the configuration of a charger 1 configured to apply an applied voltage E to a member to be charged 3 in steps.
The charger 1 is divided into three blocks 1E, 1F, and 1G, and insulators 19, 19 are inserted between the blocks to prevent electrical contact.

The insulators 19 and 19 were made of a flexible PET film, and had a thickness of 0.5 mm. The length was designed to be almost the same as that of the supporting fine wire 2B, and was designed not to swing on the member to be charged (photosensitive member) 3. Fixed layer 2A
Is patterned at the time of application, and a gap of about 0.5 mm is formed between each part. Insulator (PET film) 10
After the support fine wire 2B is implanted in the fixing layer 2A, it is set in the gap. From the portion of each fixed layer 2A, the electrodes 2C, 2C,
2C so that each block 1E, 1F, 1G
Can be independently applied with the voltage E.

Each of the electrodes 2C, 2C and 2C is connected to a resistor Rb, Rb ',
Using Rb ″, the voltage was set at −200, −400, and −500 V. The presence or absence of discharge was observed by the amount of ozone. Ozone was not detected at all, and it was confirmed that the ozone was effective. (Embodiment 7) Fig. 7 shows an image forming apparatus for forming an electrostatic latent image on the dielectric 3 using the charger 1. An image forming apparatus is composed of processes of charging, developing, transferring, and removing static electricity, and a normal image forming apparatus has an exposure process (exposure step), in which an electrostatic latent image is formed. In the forming apparatus, a latent image is formed by a charging process, which is realized by selectively charging only an arbitrary area, and is omitted here because it is the same as a normal electrophotographic process except for charging and discharging. I do.

FIG. 8 shows an outline of the charger 1. The charger 1 includes a charged dot 20 formed of an electric conductor, a wiring 21 connected to the charged dot 20, an insulating film (SiO 2).
₂ ) Consists of 22, connector section 23 and base 24. The charged dot 20 may be a conductor, and may be, for example, a metal, a conductive organic substance, an inorganic semiconductor, an insulating substance to which a conductive filler is attached, or the like. This time, metal, especially Cu, was used because of its simple manufacturing process.

The electrode portion 25 of the charged dot 20 has CNT
4 are arranged. The CNTs 4 are formed on Cu and made by thermal CVD using Fe fine particles as a catalyst. Since CNTs 4 are not generated from a place where there is no catalyst, they are generated only at the electrode portion 25. The length of the CNTs 4 is several tens of μm and formed uniformly. If they are in contact, they are slightly bent by the pressing pressure. Thereby, even if the gap slightly shifts, the contact is always performed due to the bending.
In this way, slight gap displacement is no longer a problem. Note that the manufacturing method is not limited to this, and there is also a method in which the CNTs 4 produced by arc discharge are dispersed in a resin, applied to the electrode unit 25, and the surface is polished to project the CNTs 4.

Each of the charged dots 20 is set to about 30 μm,
1 was 5 μm. Dot spacing is 15μm, vertical
The six rows are arranged (note that FIG. 8 schematically shows the charged dots 20 large, so the scale is not correct). As a result, it is possible to substantially obtain the number of pixels of the 3000 dpi level. Further, an expensive optical system such as an LED array is not required, the number of rows can be increased at a low cost, and a higher number of pixels can be easily obtained.

The insulating substrate 24 is made of Si substrate, and the wiring 2
1 used Cu metal. The manufacturing method is to form a film by sputtering,
Wiring (Cu) 21 and insulating film (SiO2) 22 are each 500n
m and 1 μm.

In the case of a normal contact-type charger 1, there is a problem that the photosensitive member is scraped by contact friction in view of the life of the photosensitive member. In this embodiment, instead of the photoconductor,
A general dielectric material is used as the member to be charged 3, and is resistant to defects such as scraping. Therefore, there are few restrictions on the hardness of the charger 1, and there is no problem even with a hard material such as Cu or SiO2.

The manufacturing method employed a dual damascene method. A through hole is formed in the insulating film (SiO 2) 22, and a groove is also formed in a region to be the charged dot 20 by wet etching. The wiring 21 was formed by sputtering Cu in the region, and the step was removed by CMP to form a flat surface. As a result, the charger 1 having the shape shown in FIG. 8 is obtained.

The wiring 21 passes under the insulating film 22 in the vertical direction. The wiring 21 is connected to an integrated circuit (IC) 26 storing data by a connector (heat seal connector) 23. A voltage E of several hundred volts can be applied to the charged dots 20 from the integrated circuit (IC) 26.

The voltage E is applied to dots required for image formation. As a result, charging is performed only where necessary. Since a large voltage is applied between the wirings 21, the wiring 21 is designed so that the wirings 21 can be separated as much as possible so as not to cause a problem.

In addition, a protection diode was provided on each wiring 21. The protection diode can be formed at the same time as the Cu wiring is applied. Since the Si base 24 is selected, the usual semiconductor process can be used as it is. Although not actually performed in the present embodiment, an IC can be provided on the Si base 24.

The photosensitive member is usually used as the charged member 3, but in this embodiment, any member can be used as long as it can hold static electricity. Also, the film thickness does not need to be severely uniform as in the case of a normal photoconductor, and this is particularly true in the case of binary writing digital.

The structure of the member 3 to be charged is a thin film of a dielectric material having a thickness of about 100 μm on the surface 3A and a conductive member 3B holding the thin film. By dropping the base 3B to ground, a voltage can be applied during charging.

The substrate 3B is the same as a normal photoreceptor, and can be made of a general metal. In this case, Al was used. Al is formed into a cylinder to suppress surface roughness. A dielectric film is formed thereon. A dipping method is adopted for simplicity of production, and a hot melt type dielectric is used. Any material may be used as long as it is a dielectric, and its choice is selected from the simplicity of the manufacturing method. For example, organic compounds such as PET (polyethylene terephthalate) and PVA (polyvinyl alcohol) correspond to this. In addition, SiO2, a-Si, SiN, etc. are easy to manufacture because of their track record of being used in semiconductors. In this example, PET was used. PET has many uses, is attractive in terms of cost, and has well-known physical properties in production.

Since the photoreceptor is usually used for the static eliminator 18, the static elimination is performed by performing exposure. But,
In this embodiment, a method of releasing the electric charge on the surface by contacting the conductive material is employed. However, it is not limited to this. Further, the conductor is not limited to a solid, and for example, a liquid such as water can be adopted.

This time, the present embodiment was carried out by adding a static elimination function to the ordinary cleaning process. As a result,
The two steps of static elimination and cleaning become one step, which is simple. Conventionally, the toner on the surface of the photoconductor is scraped off by pressing a material having low hardness and high elasticity such as PC (polycarbonate) or silicone rubber against the photoconductor. Degradation of the surface, which is a problem with photoreceptors (OPCs), has been devised so that a new surface is constantly produced by shaving the surface in this process.

In the present embodiment, the cleaning blade is made conductive and dropped to the ground, so that the static eliminator 1 is removed.
8 can be shared. The method of making the blade conductive is realized by adding a conductive filler to a commonly used resin.

The filler is used without impairing the elasticity of the resin.
Ketjen black, which is carbon particles, was used to obtain a large conductivity. A sufficient volume resistance can be obtained at a concentration of about 5 wt%. In this embodiment, other equalizer functions and the like were diverted as they were simply by making the normal cleaning blade conductive. In this state, it was confirmed by the actual machine that the static electricity removal at the 60 cpm level was possible by setting the contact width (nip width) to about 2 mm. (Embodiment 8) In this embodiment, the charging device 1
In this case, an electrostatic latent image is formed by a charging process according to the present invention, and the image forming process is the same as that in FIG.

The present embodiment is characterized in that light is used to select a latent image forming area.

As shown in FIG. 9, the charger 1 has an LED
Array 25, optical system 26, transparent conductor 27, optical semiconductor 2
8. It is composed of carbon nanotubes 4.

Light is applied to an arbitrary area by the LED array 25. The optical semiconductor 28 has a characteristic of lowering the resistance value only in a region irradiated with light. Therefore, by selectively irradiating light, an area can be selected and an electrostatic latent image can be formed. The charger 1 includes a roller section and an LED light source section.

It is conceivable to use lamp light or laser light for the light source section. In this embodiment, an LED array 25 having a plurality of LEDs is used. In recent years, the LED array 25 has been applied as a high-density writing system for a copying machine or the like, and has a great deal of technical accumulation.

The LED had a diameter of about 30 μm, and a space of 20 μm was provided between the LEDs. In addition, LED has 6 rows in the vertical direction,
Again, they are installed at intervals of 20 μm. The wavelength of the LED was 650 nm. An optical system 26 having a lens function is incorporated between the LED and the charged body 3 so that the LED light efficiently illuminates the charged body 3. The optical system 26 has a commonly used macro lens array. At this time, it is necessary to take measures to prevent interference fringes and the like from appearing. This is fixed inside the roller of the transparent substrate 24 so that the charged member 3 is always irradiated.

The voltage applying roller was constructed as follows.

A conductive transparent film is formed on the surface of the transparent substrate 24, and the optical semiconductor thin film 28 is formed thereon. In addition, an electrode can be removed from a conductive film in a lower layer. The transparent substrate 24 may be made of glass, plastic, or the like. However, acrylic resin is used for its versatility and mechanical strength, and the transparent substrate 24 is formed into a cylinder. The diameter of the cylindrical base 24 is designed to be 20 mmΦ, and the thickness is set to 2 mm to obtain sufficient strength.
And The friction between the cylinder and its support should be small and free to rotate. In addition, the cylindrical support is provided with mobility so that the charged body 3 and the charger 1 are always in contact with a sufficient pressure.

The surface on the substrate 1 is transparent and conductive,
In addition, a transparent conductor 27 having appropriate elasticity is formed. In this case, the transparent conductor 27 employs a method in which transparent conductive fine particles are dispersed in an elastic transparent matrix. This means that the fine particles maintain conductivity and the base material maintains elasticity. In this embodiment, ITO, zinc oxide, titanium oxide, antimony oxide,
Pulverize transparent conductive materials such as iridium oxide, antimony and tantalum-doped tin oxide zirconium oxide into micron-order fine particles, which are then made of transparent polycarbonate, polyurethane, acrylic, epoxy, silicone, alkyd, vinyl chloride-vinyl acetate It was sufficiently dispersed in a base material such as a copolymer. The conductivity may be about 1 × 10 4 Ωcm. Since the transparency is not so required, the film thickness was set to 10 μm.

The optical semiconductor 28 is formed on the upper layer, that is, the layer in contact with the member 3 to be charged. The optical semiconductor 28 has a function of reducing the resistance only in the region where light is applied. This is based on the generation of carriers having electrical conductivity by light.

Materials having such properties include inorganic substances.
Many substances are known, such as Si, ZnO, a-Si, GaAs, Ge, and TiO2. In organic substances, squarylium dyes, metal-free phthalocyanine-based, metal phthalocyanine-based, azulenium salt-based dyes, squalic acid derivatives, trisazo pigments, thiapyrylium salts and polycyclic quinone-based, perylene-based, and indigo, which are usually used for photoreceptors, are used. Derivatives or bisazo pigments are used. Further, a layer can be formed by putting these in a binder material such as polyvinyl butyral resin. In this embodiment, a metal phthalocyanine-based organic semiconductor is used. This is mixed with a binder resin to form this layer. The film thickness was about 20 μm. The outermost surface layer is formed by CNT4. Features of CNT4,
Since the formation method and the like have been described in the second embodiment, they are omitted here. (Embodiment 2) (Example 9) The charger, the member to be charged and the like used in Example 2 were used. That is, the roller type of Example 2 was employed this time. However, even with other shapes such as blade type,
The tendency of the CNTs 4 to degrade remains unchanged, and the results this time do not depend on the shape. Here, only the driving method will be described.

In this embodiment, the driving waveform is pulsed.
FIG. 14 shows the waveform. The pulse P was a rectangular wave, and its frequency was 10 kHz. The voltage was set to -500 V at the peak and 0 V at the time of dip. The evaluation of the life of the CNT 4 is determined from its characteristic deterioration. In the case of the normal CNT 4 charger 1, charging of about 80%, or about -400V, can be expected by applying -500V. However, when the CNT 4 deteriorates, its potential drops.
In this judgment, it was judged that the life was over when the value was reduced by half to -200V. The service life was measured by continuous operation.
As a result, it was found that the time was about 10 hours. This indicates that the life of the charger is much longer than that of the DC drive of Comparative Example 1. Comparative Example 1 The configurations of the charger 1 and the member to be charged 3 are the same as those in the ninth embodiment. In Comparative Example 1, the applied voltage was changed to DC voltage −5.
00V. As a result, the charger deteriorates in a very short period of time, about 2 minutes. (Embodiment 10) The driving waveform in this embodiment is as shown in FIG. The applied voltage was -500 V at the peak, and the rate of change of the slope was 5 × 10 ⁶ (V / sec).

Here, the change rate K (inclination) of the drive waveform was set as follows. K <C1 × 10 ⁻¹² / Ca Ca: capacity per unit area of the member to be charged (C / cm ² ) C1: CNT density: number of CNTs per unit area (books / cm ² ) K = dVa / dt: Inclination (voltage increase rate per unit time) A photosensitive member is used as the charged member 3, the film thickness is 25 μm, the relative dielectric constant is 3.4, and the capacitance Ca per fixed area (cm ² ) is about 100 pF (10 ^-10 F). The density of the CNTs 4 depends on the method of its production. For example, if it is a method of mixing with the resin, it can be controlled by its concentration. Also CVD
When forming later, the concentration is controlled by patterning or the like. The density of the CNT is evaluated by observing with an SEM (electron microscope). This time, 10 /
It was controlled to be μm ² (10 ⁹ lines / cm ² ). Thus, the right side of the above equation is the right side = C1 × 10 ⁻¹² / Ca = 10 ⁹ × 10 ⁻¹² / 10 ⁻¹⁰ = 1
0 ⁷ to become.

That is, the inclination K on the left side may be 10 ⁷ or less.

In this case, the left side is K = dVa / dt, and the applied voltage is 500 V (the sign is negative, but the magnitude is discussed here). Should satisfy the following conditions. 500 / Tc <10 < ⁷ >Tc> 500 * 10 < ^-7 >Tc> 5 * 10 < ^-5 > = 50 [mu] sec The charging evaluation was performed using the driving waveform P thus created.
As a result, the life of the charger 1 was further improved to nearly 1,000 hours. (Comparative Example 2) All were prepared under the same conditions as in Example 10, and the inclination was set to 5 × 10 ⁷ (V / sec).

As a result, it was found that the life was reduced to 10 hours, which was not a practical level. Prepared in Comparative Example 3 and Example 10, all the same conditions, and the inclined ^{5 × 10 8 (V / sec} ).

As a result, it was found that the life was reduced to 5 hours, which was not a practical level. (Comparative Example 4) All were prepared under the same conditions as in Example 10, and the inclination was 1 × 10 ⁶ (V / sec).

The service life was increased to 2,000 hours, which proved to be a practical level. (Embodiment 11) The configuration and the like of the charger 1 are the same as those shown in Embodiment 9, and only the driving method will be described here.
The slope of the pulse is the same as that shown in Embodiment 11,
K was set to 5 × 10 ⁶ (V / sec). FIG.
As shown in the figure, the interval between the pulses was 100 μsec.

That is, the following conditions were satisfied. T1 <10 ^-5 / S1 S1: Relative speed of the charger to the object to be charged (m / sec) T1: Pulse interval (sec) This time, consider a copy machine of about 10 cpm (10 A4 plates per minute) The speed of the member to be charged was 80 mm / sec (8 × 10 ^-2 m / sec). Here, the left side of the above equation is: left side = 10 ⁻⁵ / S1 = 10 ⁻⁵ / 8 × 10 ⁻² = 1.25 × 10 ⁻⁴ (sec), and right side = T1 <10 ⁻⁴ (sec) = 125 (μsec) That is, under this condition, the unevenness can be reduced by setting the pulse interval to 125 μsec or less. In this embodiment, the pulse interval is set to 100 μsec.

Evaluation of uneven charging is performed under these conditions. This can be observed in a halftone image of a normal copying machine. As a result, it was confirmed that there was no uneven charging. (Comparative Example 5) Under the same conditions as in Example 11, the pulse interval was set to 2
00 μsec. As a result, some uneven charging was observed. (Comparative Example 6) Under the same conditions as in Example 11, the pulse interval was set to 1
25 μsec. As a result, charging unevenness was observed to a considerable extent. (Comparative Example 7) Under the same conditions as in Example 11, the pulse interval was set to 4
00 μsec. As a result, uneven charging was observed. (Comparative Example 8) The applied voltage was -800 V according to Example 11.
And From FIG. 13, discharge may occur at this voltage, and as expected, slight uneven charging was observed. (Comparative Example 9) According to Example 11, the applied voltage was -1000.
V. From FIG. 13, discharge may occur at this voltage, and uneven charging was observed as expected.

The following table is a list of the experimental results.

[0135]

[Table 1]

-: Not evaluated Life: Indicates the time when the characteristic value is reduced by half Unevenness: Visual evaluation with halftone image

[0137]

According to the first aspect of the present invention, CNT
Since the amount of current flowing through one line is limited and the density of the CNTs and the total resistance of the charger are limited, a large amount of current flows through the CNTs, and the life of the charger is extended without deterioration.

According to the second aspect of the present invention, by performing the charging stepwise, the potential difference at each step can be reduced. Because the potential difference can be limited, the current value can also be automatically limited. By using both the method of limiting with a resistance and the method of limiting with a voltage, it is possible to reliably prevent the CNT from deteriorating.

According to the third aspect of the present invention, the contact portion and the non-contact portion are naturally formed by using the blade type. In this non-contact portion, the distance between the member to be charged and the charger is several microns or less, and an appropriate gap can be formed very easily.

By making the surface of the charger a brush, the area of the surface of the charger is remarkably improved. Thereby, the number of CNTs per unit area of the member to be charged can be increased. By increasing the number of CNTs, the amount of current flowing through one CNT can be reduced, and deterioration can be prevented.

According to the fourth and fifth aspects of the present invention, by forming a roller, a portion that is not in contact with the member to be charged is formed. Undegraded CNTs can be selectively projected. As a result, the life of the charger can be extended.

According to the sixth aspect of the present invention, a charging system that does not damage the photoreceptor can be achieved, and the cost can be reduced, and the generation of ozone, NOx and the like is extremely small, the reliability is long, and the reliability is low. Image forming apparatus equipped with a high-charger.

According to the seventh aspect of the invention, it is possible to avoid deterioration of the photosensitive member, which is a main factor determining the life of the image forming apparatus, and to directly form an electrostatic latent image without using a photosensitive member. By forming, the life of the image forming apparatus can be prolonged and the cost can be reduced.

According to the eighth aspect of the present invention, since pulse driving is performed, it is possible to synchronize so that current flows to all CNTs at the same time. Since the value of the current flowing through the book is determined, the deterioration of the CNT can be further prevented, and thus, stable charging can be performed over a long period.

According to the ninth aspect of the invention, by defining the slope of the driving waveform of the pulse, it is possible to prevent a large current from flowing and to suppress the deterioration of the CNT.

According to the tenth aspect of the present invention, since the value of the current flowing through each one of the CNTs is defined, the deterioration of the CNTs can be further prevented.

According to the eleventh aspect, by making the pulse interval sufficiently small, it is possible to eliminate a non-charged area, thereby preventing uneven charging.

According to the twelfth aspect, by controlling the pulse voltage to be equal to or lower than the discharge starting voltage, it is possible to reduce uneven charging.

[Brief description of the drawings]

FIG. 1 is a diagram showing an outline of a charger of Example 1 of Embodiment 1 of the present invention.

FIG. 2 is a diagram illustrating an outline of an image forming apparatus according to a second embodiment of the first embodiment of the present invention;

FIG. 3 is a diagram showing an outline of a charger of Example 2 of Embodiment 1 of the present invention.

FIG. 4 is an enlarged sectional view of a main part of a member to be charged according to a second embodiment of the first embodiment of the present invention;

FIG. 5 is an enlarged sectional view of a main part of the charger of Example 5 of Embodiment 1 of the present invention.

FIG. 6 is a diagram showing an outline of a charger of Example 6 of Embodiment 1 of the present invention.

FIG. 7 is a diagram illustrating an outline of an image forming apparatus according to a seventh embodiment of the first embodiment of the present invention;

FIG. 8 is a diagram showing an outline of a charger of Example 7 of Embodiment 1 of the present invention.

FIG. 9 is a diagram showing an outline of a charger of Example 8 of Embodiment 1 of the present invention.

FIG. 10 is an equivalent circuit diagram for explaining a relationship between an applied voltage applied to the CNT and deterioration of the CNT. FIG. 10A is an explanatory diagram when a voltage is uniformly applied to the CNT. (b) is an explanatory diagram in the case where a voltage is applied to only a part of the CNT.

FIG. 11 is an explanatory diagram of a drive waveform of an applied voltage applied to the CNT, showing a triangular (sawtooth) drive waveform.

FIG. 12 is a diagram in which a change in a surface potential of a charged body with respect to a distance between the charged body and a charger is plotted.

FIG. 13 is an explanatory diagram illustrating a relationship between a surface potential of a member to be charged and an applied voltage, and is a diagram illustrating charging characteristics of a CNT.

FIG. 14 is a diagram showing a pulse-like drive waveform of Example 9 of the second embodiment of the present invention.

FIG. 15 is a diagram showing a sawtooth-shaped drive waveform of Example 10 of Embodiment 2 of the present invention.

FIG. 16 is a diagram showing a sawtooth drive waveform of Example 11 of Embodiment 2 of the present invention, showing a state in which the intervals between the generation of the sawtooth drive waveforms are close.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Charger 3 ... Charged object 4 ... CNT Rb ... External voltage E (Va) ... Applied voltage

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Yukie Suzuki 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Company (72) Inventor Hiroyoshi Shoko 1-3-6 Nakamagome, Ota-ku, Tokyo Stock Ricoh Company (72) Inventor Akiyoshi Murakami 1-3-6 Nakamagome, Ota-ku, Tokyo F-term (reference) 2R200 FA07 GA23 HA02 HA13 HA29 HB07 HB08 HB12 HB14 HB45 HB48 MA06 NA08 NA09 NA11 NA23 PA02 PA09 PA11

Claims (12)

[Claims] 1. A charging device in which carbon nanotubes are held on the surface of a charger facing a member to be charged and charge is performed via field emission, the amount of current flowing per carbon nanotube is 10 ^-12 A or less. And a density C1 (lines / cm ² ) and a resistance Rb of the carbon nanotube satisfy the following conditions. C1 × Rb> Va / 10 ⁻¹² Va: Difference in charging potential applied to the member to be charged (V) Rb: Total resistance value (Ωcm ² ) applied to the charging circuit per unit area to be charged 2. The charging device according to claim 1, wherein the voltage of the object to be charged is increased stepwise. 3. The charging device according to claim 1, wherein a shape of the charging device body is a blade type or a brush type. 4. The charger according to claim 1, further comprising a polishing member for polishing a surface of the charger main body. 5. The charger according to claim 4, wherein the shape of the charger main body is a roller type. 6. An image forming apparatus using the charger according to claim 1. Description: 7. An image forming apparatus, wherein an electrostatic latent image is formed by directly applying a voltage to a member to be charged, using the charger provided with the carbon nanotube according to claim 1. 8. A carbon nanotube is held on a surface of a charger facing a member to be charged, charged by electric field emission, and the amount of current flowing per carbon nanotube is 10 ^-12 A or less. Density C1
(Charging / cm ² ) and a resistance Rb satisfying the following conditions, and a driving voltage is applied in a pulsed manner. C1 × Rb> Va / 10 ⁻¹² Va: potential difference (applied voltage) applied to the member to be charged (applied voltage) (V) Rb: total resistance value (Ωcm ² ) applied to the charging circuit per unit area to be charged 9. The charging method for a charging device according to claim 8, wherein the charging is performed with a drive waveform having an inclined rising edge of the pulse. 10. The charging method for a charging device according to claim 9, wherein the slope of the driving waveform satisfies the following expression. K <C1 × 10 ⁻¹² / Ca Ca: capacity per unit area of charged body (C / cm ² ) K = dVa / dt: slope (voltage increase rate per unit time) 11. The charging method for a charger according to claim 9, wherein the interval between the pulses satisfies the following condition. T1 <10 ^-5 / S1 S1: relative speed of the charger to the object to be charged (m / sec) T1: pulse interval (sec) 12. The charging method for a charging device according to claim 9, wherein a peak value of the pulse is suppressed to a discharge starting voltage or less.