JPH07191583A - Destaticizing device and image forming device - Google Patents

Abstract

PURPOSE:To evenly and uniformly destaticize a photoreceptor without using a destaticizing lamp by providing the surface of the photoreceptor with a conductive destaticizing member for removing the charges remaining thereon. CONSTITUTION:This image forming device is so constituted that a photosensitive drum 1 having a semiconductive protective film 2 on a photosensitive layer 3 rotates at a uniform speed. A part of the photoreceptor 1 is in contact with the roller-shaped destaticizing device having the conductive destaticizing member and the charges remaining in the photosensitive drum 1 are moved to the conductive destaticizing member side and are thereby erased. Metals, such as aluminum, iron and copper, conductive high molecular compd., such as polyacetylene and polypyrrole, insulating resins, such as polycarbonate and polyester, of which the surfaces are laminated with conductive materials and binder resins in which conductive particles, such as carbon black, are dispersed, are used as the material of the conductive destaticizing member. A DC voltage or AC voltage or voltages superposed with both are impressed to the conductive destaticizing member in order to enhance a destaticization effect.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a static eliminator used in an image forming apparatus for forming an image by an electrophotographic system such as a copying machine, a laser printer and a fax machine, and an image forming apparatus.

[0002]

2. Description of the Related Art A conventional image forming apparatus has a photosensitive drum for carrying an electrostatic latent image in a main body of the apparatus, and an exposure lamp is provided after a surface of the photosensitive drum is uniformly charged by a charging device. The light is emitted to the surface of the photoconductor drum to form an electrostatic latent image on the surface of the photoconductor drum. This electrostatic latent image is developed by a developing device, and the obtained toner image is transferred to transfer paper. When the transfer process of the toner image is completed, the toner remaining on the surface of the photoconductor drum is cleaned by the cleaning device, and then the light from the charge eliminating lamp is irradiated onto the surface of the photoconductor drum, so that the surface of the photoconductor drum is discharged. The charge is erased.

By irradiating the surface of the photosensitive drum with the light from the charge eliminating lamp, the surface potential of the photosensitive drum is set to approximately zero volt.

Such a static elimination lamp is selected in consideration of the sensitivity characteristics of the photosensitive drum, and for example, a white light source provided with a predetermined filter to irradiate the transmitted light or neon. Lamps or light emitting diodes have been used.

[0005]

However, all of these light sources have the problems that they generate heat and that a proper light amount and emission spectrum must be taken into consideration due to restrictions such as the sensitivity characteristics of the photosensitive drum. Was there.

Further, in the reversal development type image forming apparatus, since the photosensitive drum is charged with a polarity opposite to that of the primary charging in the transfer process, there is a problem that the charge cannot be removed by the charge eliminating lamp. .

The object of the present invention is to generate no heat, and
An object of the present invention is to realize a charge eliminating device of an image forming apparatus capable of efficiently eliminating charge even in a photoconductor drum having a different sensitivity characteristic or an image forming apparatus of a reversal developing system.

[0008]

SUMMARY OF THE INVENTION That is, the present invention is a static eliminator used for an electrophotographic photosensitive member having a semi-conductive protective film, which is electrically conductive to remove electric charges remaining on the photosensitive member. A static eliminator having a static eliminator.

Further, the present invention is the above static eliminator, wherein the semiconductive protective film contains conductive fine particles.

Further, the present invention is an image forming apparatus of a reversal developing system, which is characterized by having the above-mentioned charge eliminating device.

Further, the present invention is an image forming apparatus characterized by having the above-mentioned charge eliminating device.

In the electrophotographic process, the photoreceptor is charged by a corona charging method or a non-corona charging method such as a roller charging method, a brush charging method or an electrode charging method.

In the present invention, since a photoreceptor having a semiconductive protective film is used, when the above charging method is performed,
As shown in FIG. 1, charges are injected from the surface of the photoconductor, and charging is performed at the interface between the semiconductive protective film and the photosensitive layer.

Therefore, as shown in FIG. 2, when the conductive charge eliminating member of the present invention is brought into contact with the surface of the photoconductor, the charge is removed to the conductive charge eliminating member side.

Further, in the charge eliminating device of the present invention, it is possible to remove the charge having the opposite polarity to the primary charge of the photosensitive drum, which is applied in the transfer process of the reversal development system, by the same process as described above.

In addition to the roller shape shown in FIG. 2, the conductive static eliminating member of the present invention may have a blade shape, a rotating belt shape, a brush shape, a piece shape, a magnetic brush shape using conductive particles, or the like.

From the standpoint of static elimination, the conductive static elimination member used in the present invention preferably has a resistivity of 10 ¹⁰ Ω · cm or less.

The material of the conductive charge-eliminating member used in the present invention is a metal such as aluminum, iron or copper, a conductive polymer such as polyacetylene or polypyrrole, an insulating resin such as polycarbonate or polyester, or a rubber surface. It is possible to use those laminated or coated with another conductive material, those in which conductive particles such as carbon black are dispersed in a binder resin to control the conductivity, and the like.

Further, in order to improve the efficiency of static elimination, a DC voltage and an AC voltage or a voltage obtained by superimposing AC on a DC voltage may be applied to the conductive static elimination member of the static eliminator of the present invention.

The semiconductive protective film in the present invention is one in which conductive fine particles are dispersed and contained in a binder resin.

The binder resin may be a thermoplastic resin or a curable resin, and ordinary commercially available resins such as acrylic resin, epoxy resin, silicone resin, guanamine resin, melamine resin, polyurethane resin, polycarbonate resin, polyester resin and fluororesin. Is mentioned.

As the conductive fine particles, one or more particles selected from metals such as aluminum and nickel, zinc oxide, tin oxide, indium oxide, and metal oxides such as a solid solution or a fused body of these substances are appropriately selected. Can be used.

The particle size of the conductive fine particles is preferably 0.3 μm or less from the viewpoint of translucency of the film, and is 0.1.
More preferably, it is less than or equal to μm.

The electric resistance of the semiconductive protective film is 10
The range of ⁷ to 10 ¹⁵ Ω · cm is preferable.

Various additives may be added to the semiconductive protective film for the purpose of improving dispersibility, adhesiveness or smoothness.

The semiconductive protective film can obtain a binder resin, conductive fine particles and necessary additives on the photosensitive layer.

As the photosensitive layer, a conventionally known layer can be used.

As the conductive support, a metal such as aluminum, nickel or stainless steel, a plastic sheet or glass having a conductive film, or a paper which has been subjected to a conductive treatment can be used.

[0029]

EXAMPLES The present invention will be described below with reference to examples. (Example 1) Hereinafter, the present invention will be described with reference to examples. FIG. 2 is a schematic diagram illustrating an embodiment of the present invention.

The photosensitive drum 1 having the semiconductive protective film 2 on the photosensitive layer 3 is constituted so as to rotate at a constant speed in the direction of arrow 7.

A part of the photoconductor 1 is in contact with a roller-shaped static eliminator 6 having a conductive static eliminator, and the photoconductor drum 1
The electric charge remaining therein is moved and erased to the side of the conductive charge eliminating member.

As described above, except for the portion for removing charge,
All the same means as those of the conventional electrophotographic apparatus can be adopted.

The photosensitive drum 1 has the photosensitive layer 3 as described above.
The semi-conductive protective film 2 is provided on the surface of
The photosensitive drum 1 used was formed as follows.

50 parts of conductive titanium oxide powder coated with tin oxide containing 10% antimony oxide (parts by weight, the same applies hereinafter), 25 parts of phenol resin, and methyl cellosolve 2
0 parts, 5 parts of methanol and 0.002 parts of silicone oil (polydimethylsiloxane polyoxyalkylene copolymer, average molecular weight 3000) were dispersed for 2 hours in a sand mill using φ1 mm glass beads to prepare a conductive layer coating material. .

Aluminum cylinder (φ80mm × 3
60mm), and apply the above coating by dip coating,
It was dried for 0 minutes to form a conductive layer having a film thickness of 20 μm.

Next, 10 parts of alcohol-soluble copolymer nylon resin (average molecular weight 29000) and 30 parts of methoxymethylated 6 nylon resin (average molecular weight 32000) were dissolved in a mixed solvent of 260 parts of methanol and 40 parts of butanol.

This prepared solution was applied onto the conductive layer by dip coating to form an intermediate layer having a film thickness of 1 μm.

Next, the structural formula

[0039]

[Chemical 1] 4 parts of disazo pigment, 2 parts of polyvinyl butyral (butyralization ratio 68%, weight average molecular weight 24000) and 34 parts of cyclohexanone are dispersed for 12 hours in a sand mill using φ1 mm glass beads, and 60 parts of tetrahydrofuran is added to generate an electric charge. A layer dispersion was prepared. This dispersion was applied onto the above intermediate layer by dip coating and dried at 80 ° C. for 15 minutes to form a charge generation layer having a film thickness of 0.15 μm.

Next, the structural formula

[0041]

[Chemical 2] Of styryl compound of 10 parts and polycarbonate (weight average molecular weight of 46000) of 10 parts of dichloromethane,
It is dissolved in a mixed solvent of 40 parts of monochlorobenzene, and this solution is dip-coated on the above-mentioned charge generation layer, and the solution is mixed at 120 ° C. for 6 minutes.
It was dried for 0 minutes to form a charge transport layer having a film thickness of 19 μm.

Next, the structural formula

[0043]

[Chemical 3] 60 parts of acrylate monomer, 30 parts of tin oxide fine particles having an average particle size of 400Å before dispersion, 0.1 part of 2-methylthioxanthone as a photoinitiator, and 300 parts of toluene are mixed and dispersed in a sand mill for 48 hours. It was

This prepared solution was formed on the above charge transport layer by a beam coating method, dried, and then photocured with a high pressure mercury lamp at a light intensity of 8 mW / cm ² for 20 seconds.
A semiconductive protective film was provided. The thickness of this semiconductive protective film was 7 μm, and the resistivity was 10 ¹¹ Ω · cm.

The photosensitive drum produced in this manner was melt-kneaded with 100 parts of chloroprene rubber and 15 parts of conductive carbon, and a stainless steel shaft was passed through the center to obtain φ20 × 340 mm.
It was attached to a positive development type copying machine having a static eliminator composed of a conductive static eliminator molded so that the electrophotographic characteristics were evaluated.

When charged in the above copying machine, -8
An initial dark area potential of 00 (V) was obtained, and the potential after static elimination was −
The residual potential was 25 (V), which was the same as that when a charge eliminating lamp was used.

Further, even after the processes of primary charging-exposure-development-transfer-static elimination were repeated 10,000 times, the potential increase after static elimination was 15 (V), and a stable image without unevenness or density decrease was obtained. .

Example 2 As an acrylate monomer in the semiconductive protective film of Example 1

[0049]

[Chemical 4] A photosensitive drum was produced in the same manner as in Example 1 except that was used.

The photosensitive drum manufactured in this manner is shown in FIG.
As shown in, the average particle diameter is 30 μm and the resistivity is 10 ⁶ Ω.
cm of Ni conductive particles 8 and the distance between the surface of the photosensitive member 1 and the surface of the electrode 9 is 1 mm, and a positive developing method copying having a charge eliminating device by applying a bias potential of AC 500 (V) Mounted on a machine and evaluated for electrophotographic properties.

When charged in the above copying machine, -7
An initial dark area potential of 80 (V) was obtained, and the potential after static elimination was −
The residual potential was 25 (V), which was the same as that when a charge eliminating lamp was used.

Furthermore, even after the processes of primary charging-exposure-development-transfer-static elimination were repeated 10,000 times, the potential increase after static elimination was 5 (V), and a stable image without unevenness or density decrease was obtained. .

Example 3 As an acrylate monomer in the semiconductive protective film of Example 1

[0054]

[Chemical 5] A photosensitive drum was produced in the same manner as in Example 1 except that was used.

The photoconductor drum manufactured in this manner is shown in FIG.
As shown in, the average particle diameter is 20 μm and the resistivity is 10 ⁵ Ω.
cm magnetic conductive particles 12 are used, and the distance between the surface of the photoreceptor 1 and the surface of the mag roll (10 magnets of 800 gauss are built in 10 poles and rotates at 700 rpm) 11 is 0.2.
The electrophotographic characteristics were evaluated by mounting on a copier of a positive development system having a static eliminator having a size of mm.

When charged in the above copying machine, -8
An initial dark area potential of 00 (V) was obtained, and the potential after static elimination was −
The residual potential was 20 (V), which was the same as that when the charge eliminating lamp was used.

Further, the process of charging-discharging was performed 10,000 times.
Even after repeated operations, the potential rise after static elimination was 10 (V), and a stable image without unevenness or density decrease was obtained.

Example 4 A conductive layer and an intermediate layer were provided on an aluminum cylinder of φ30 mm × 260 mm by the same method as in Example 1.

Next, the structural formula

[0060]

[Chemical 6] 4 parts of disazo pigment, 2 parts of polyvinylbenzal (benzalization rate 80%, weight average molecular weight 11,000), and 30 parts of cyclohexanone were dispersed for 20 hours in a sand mill using φ1 mm glass beads, and then 60 parts of methyl ethyl ketone was added. A charge generation layer dispersion liquid was prepared.
This dispersion is applied onto the above intermediate layer by dip coating, and the dispersion is applied at 80 ° C. for 15
After drying for a minute, a charge generation layer having a film thickness of 0.10 μm was formed.

Next, the structural formula

[0062]

[Chemical 7] 10 parts of the charge transport material and 10 parts of polycarbonate (weight average molecular weight 25000) are dissolved in a mixed solvent of 20 parts of dichloromethane and 40 parts of monochlorobenzene, and this solution is dip-coated on the charge generation layer at 120 ° C. 60
After being dried for a minute, a charge transport layer having a film thickness of 15 μm was formed.

Next, the structural formula

[0064]

[Chemical 8] 60 parts of an acrylate monomer represented by the following formula, 30 parts of ITO fine particles having an average particle size of 380Å before dispersion, 0.06 part of benzophenone as a photoinitiator, and 300 parts of toluene were mixed and dispersed in a ball mill for 24 hours.

This formulation solution was formed on the above charge transport layer by a beam coating method, dried, and then photocured with a high pressure mercury lamp at a light intensity of 8 mW / cm ² for 30 seconds.
A semiconductive protective film was provided. The thickness of this semiconductive protective film was 4.5 μm, and the resistivity was 10 ¹² Ω · cm.

The photoconductor drum thus manufactured was attached to a reversal development type printer having a static eliminator comprising a conductive brush in which a large number of carbon fibers were bundled, and electrophotographic characteristics were evaluated.

Since the polarity of the toner in this reversal developing method is the same as the polarity of the primary charging of the above-mentioned photoconductor,
A transfer device that transfers a toner image obtained by developing a latent image onto a transfer material has a polarity opposite to the polarity of the primary charging of the photoconductor during the transfer process.

When charged in the printer, an initial dark area potential of -750 (V) was obtained, and the potential after static elimination was -15 (V), which was the same residual potential as in the case of using a static elimination lamp. .

Further, even if the processes of primary charging-exposure-developing-transfer-static elimination are repeated 10,000 times, the potential increase after static elimination is 5 (V), and a stable image without unevenness or density decrease can be obtained. It was

Example 5 As an acrylate monomer in the semiconductive protective film of Example 4

[0071]

[Chemical 9] A photosensitive drum was manufactured in the same manner as in Example 4 except that

In the reversal development system having a charge eliminating device composed of a conductive blade in which a photosensitive drum manufactured in this manner is coated with a urethane urethane resin blade on the surface of which a thermoplastic urethane solution containing 30% by weight of carbon black is applied and then cured. Was attached to the printer and the electrophotographic characteristics were evaluated.

When charging was carried out in the printer, an initial dark area potential of -770 (V) was obtained, and the potential after static elimination was -10 (V), which was the same residual potential as when a static elimination lamp was used. .

Further, even if the process of primary charging-exposure-development-transfer-static elimination was repeated 10,000 times, the potential increase after static elimination was 10 (V), and a stable image without unevenness or density decrease was obtained. .

[0075]

According to the charge eliminating device of the present invention and the image forming apparatus having the same, it is possible to eliminate the charge evenly on the photoconductor without using the charge eliminating lamp, and to perform good image reproduction. . Further, it can be applied to various photoconductors having different photosensitivity, and can also be applied to the reversal development method.

[Brief description of drawings]

FIG. 1 is a schematic diagram of charging of a photoconductor having a semiconductive protective film.

FIG. 2 is a configuration diagram of a static eliminator having a conductive static eliminator according to an embodiment of the present invention.

FIG. 3 is a configuration diagram of a static eliminator having a conductive static eliminator according to an embodiment of the present invention.

FIG. 4 is a configuration diagram of a static eliminator having a conductive static eliminator of an embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Photoconductor drum 2 Semi-conductive protective film 3 Photosensitive layer 4 Conductive support 5 Charger 6 Static eliminator having conductive static elimination member 7 Photoconductor drum rotation direction 8 Conductive particles 9 Electrode 10 Power supply 11 Mag roll 12 Magnetic conductivity particle

Claims (9)

[Claims] 1. A static eliminator used for an electrophotographic photosensitive member having a semiconductive protective film, comprising a conductive static eliminator for removing charges remaining on the photosensitive member. apparatus. 2. The static eliminator according to claim 1, wherein the semiconductive protective film contains conductive fine particles. 3. The static eliminator according to claim 1, wherein the conductive static eliminator has a roller shape. 4. The static eliminator according to claim 1, wherein the conductive static eliminator has a brush shape. 5. The static eliminator according to claim 1, wherein the conductive static eliminator has a blade shape. 6. The static eliminator according to claim 1, wherein the conductive static eliminator has a shape in which electrodes are provided in conductive particles. 7. The static eliminator according to claim 1, wherein the conductive static eliminator has a shape in which a mag roll is provided in magnetic conductive particles. 8. An image forming apparatus comprising the static eliminator according to claim 1. 9. An image forming apparatus of a reversal development type, which comprises the static eliminator according to any one of claims 1 to 7.