JP2002229223A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device that can prevent unstable electrostatic charge such as frictional electrification even in a high speed processing, can steadily forms an electrostatic latent image on a latent image carrier corresponding to a writing voltage, and is excellent in resolution. SOLUTION: In the image forming device 1 including at least the latent image carrier 2 on which an electrostatic latent image is formed, a writing device 3 having a writing electrode 3b adapted to write the electrostatic latent image on the latent image carrier 2, and a developing device 4 adapted to reversely develop the electrostatic latent image by use of negatively electrified toner, and forming the electrostatic latent image by bringing the writing electrode 3b into contact with the latent image carrier opposing the rotating direction of the latent image carrier, the surface of the latent image carrier 2 is provided with a charge injection layer and the work function of the surface of the charge injection layer is made greater than that of the surface of the writing electrode.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus for forming an image by forming an electrostatic latent image on a latent image carrier by bringing a writing electrode of a writing device into contact with the latent image carrier. About.

[0002]

2. Description of the Related Art Conventionally, in an image forming apparatus such as an electrostatic copying machine or a printer, generally, the surface of a photoconductor is uniformly charged by a charging device, and a laser beam is applied to the surface of the uniformly charged photoconductor. Alternatively, an electrostatic latent image is written on the surface of the photoconductor by exposing light of an exposure device such as LED lamp light. Then, the electrostatic latent image on the surface of the photoreceptor is developed by a developing device to form a developer image on the surface of the photoreceptor, and the developer image is transferred to a transfer material such as paper by a transfer device, and the image is formed. Has formed. In such a conventional general image forming apparatus, the exposing device, which is a writing device for an electrostatic latent image, is constituted by a laser light generating device, an LED lamp light generating device, or the like. And it has a complicated configuration.

Therefore, as an apparatus for writing an electrostatic latent image, an image forming apparatus for writing an electrostatic latent image on the surface of a latent image carrier using a needle electrode without using a laser beam or an LED lamp light is disclosed in Japanese Patent Publication No. Sho.
It has been proposed in JP-A-3-45014 and JP-A-59-33969. The image forming apparatus disclosed in the former publication has a multi-stylus having a large number of needle electrodes, and the needle electrode of the multi-stylus is simply brought into contact with the inorganic glass layer on the surface of the latent image carrier. Then, when a voltage is applied to the corresponding stylus electrode of the multi-stylus according to the input signal of the image information, the stylus electrode forms an electrostatic latent image on the latent image carrier.
According to the image forming apparatus disclosed in this official gazette, a conventional exposure apparatus is not used as a writing apparatus, and accordingly, the image forming apparatus has a small and relatively simple configuration.

However, in this image forming apparatus, since a large number of needle electrodes of the multi-stylus are simply brought into contact with the inorganic glass layer on the surface of the latent image carrier, the large number of needle electrodes are connected to the latent image carrier. It is difficult to make stable contact with the inorganic glass layer on the surface of. Therefore, it is difficult to stably charge the surface of the latent image carrier, and there is a problem that it is difficult to obtain a good image. In addition, in order to prevent the surface of the latent image carrier from being damaged by the contact of a large number of needle electrodes, it is necessary to provide an inorganic glass layer on the surface of the latent image carrier, and the configuration of the latent image carrier becomes more complicated. Become.
Moreover, since the inorganic glass layer has the property of physically adsorbed water and the charged charges of the latent image carrier leak, it is necessary to provide a means for drying the surface to prevent the influence of the physically adsorbed water. There is a problem that the size is further increased. Furthermore, simply contacting a large number of needle electrodes with the surface of the inorganic glass layer is not sufficient, and there is a high possibility that ozone (O ₃ ) is generated by the discharge from the needle electrodes, and rust on parts in the apparatus. As well as NO
Nitric acid (HNO ₃ ) generated by reacting with _x may corrode resin parts, and there is a problem that it is necessary to provide a sufficient exhaust system for discharging ozone from the inside of the apparatus.

In Japanese Patent Application Laid-Open No. 59-33969, a latent image is recorded on a dielectric layer serving as a latent image carrier by using a discharge from a needle electrode. The same problem as that of ozone generation occurs.

Further, an image forming apparatus for writing an electrostatic latent image on a latent image carrier by controlling ions generated by a corona discharger by a non-contact ion control electrode provided at the tip of an insulating substrate. Has been proposed in JP-A-6-166206. Even in the image forming apparatus disclosed in this publication, an exposure apparatus is not used as a writing device, so that the image forming apparatus has a small and relatively simple configuration. However, since the ion control electrode controls the ions generated by the corona discharger and does not directly inject the electric charge into the latent image carrier, not only does the image forming apparatus have to be large, but also However, there is a problem that the configuration becomes extremely complicated. Moreover, it is difficult to stably write an electrostatic latent image on the latent image carrier due to charging by ions. Further, since ozone is basically generated due to generation of ions, a problem similar to that of the image forming apparatus disclosed in the above-mentioned official gazette occurs.

Japanese Patent Laid-Open Publication No. Hei 6-3921 discloses that when charging a latent image carrier uniformly by using a charging roll or a charging blade, the charge is injected into the surface of the latent image carrier. Although an electrophotographic apparatus provided with a layer is described, an exposure apparatus such as a laser beam or an LED lamp light is used for writing an electrostatic latent image. As described above, the image forming apparatus is large-sized. In addition, there is a problem that the configuration becomes complicated.

For the purpose of solving such a problem, the inventors of the present invention previously disclosed in Japanese Patent Application No. 2000-298925, etc., a latent image carrier on which an electrostatic latent image is formed and a latent image carrier. A writing device including a plurality of writing electrodes for writing the electrostatic latent image; and a developing device for developing the electrostatic latent image on the latent image carrier, wherein the writing device holds the latent image. An image forming apparatus for writing an electrostatic latent image by contacting the body with a small pressing force and developing the electrostatic latent image written on the latent image carrier to form an image; It has been proposed that the image processing apparatus can be simplified and an image apparatus free of ozone or the like can be produced. However, as the process speed increases, the chance of contact between the latent image carrier and the negatively charged toner in the cleaning blade and the primary transfer unit per unit time increases. Write to increase There is a problem that filming is caused by the negatively charged toner to the pole, even when high speed,
There is a demand for an image forming apparatus that can stably apply an electrostatic latent image according to a writing voltage to a latent image carrier and has excellent resolution.

[0009]

SUMMARY OF THE INVENTION An object of the present invention is to provide an image forming apparatus which has been proposed by the present inventors, which can prevent unstable electrification such as frictional electrification even at high speed. An object of the present invention is to provide an image forming apparatus capable of stably applying an electrostatic latent image according to a voltage applied to a latent image carrier and having excellent resolution.

[0010]

An image forming apparatus according to the present invention comprises a latent image carrier on which an electrostatic latent image is formed, and a writing electrode for writing the electrostatic latent image on the latent image carrier. And a developing device that reversely develops the electrostatic latent image with negatively charged toner. The electrostatic latent image is formed by bringing the writing electrode into contact with the latent image carrier in a rotating direction. In the image forming apparatus to be formed, a charge injection layer is provided on the surface of the latent image carrier, and a work function of the surface of the charge injection layer is larger than a work function of the surface of the writing electrode.

The difference between the work function of the charge injection layer surface and the work function of the electrode surface is 0.15 eV or more.

The contact portion of the writing device with the latent image carrier is composed of a plurality of electrodes arranged in the rotation axis direction of the latent image carrier and a separating member arranged between the plurality of electrodes. The difference between the work function of the surface of the separating member and the work function of the surface of the charge injection layer is less than 0.15 eV.

The contact portion of the writing device with the latent image carrier has a linear pressure of 0.05 with respect to the rotational direction of the latent image carrier.
It is characterized by being pressed at N / mm or less.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, a negative charge is injected from a write electrode into a charge injection layer while a negative write electrode is in contact with the surface of the charge injection layer in a latent image carrier. It is possible to reduce the voltage compared to the discharge method,
Further, the charge injection layer has a charge retention property, is excellent in charge injection property, and is excellent in electron injection efficiency upon contact charging, unlike the low resistance layer. Further, since the electrostatic latent image is formed by bringing the writing electrode into contact with the rotating direction of the latent image carrier in opposition, the cleaning function of the residual toner on the latent image carrier is performed by the writing electrode. It has.

In the image apparatus of the present invention, the work function of the surface of the charge injection layer is made larger than the work function of the surface of the write electrode in such a manner, so that the latent image carrier is moved from the write electrode to the electron. , The writing charge can be quickly performed. As described above, as the process speed increases, the chance of contact between the latent image carrier and the negatively charged toner increases, and a resin layer may be formed on the surface of the writing electrode by filming of the remaining toner. By making the work function of the surface of the charge injection layer larger than the work function of the surface of the write electrode, it is possible to improve the electron mobility from the write electrode to the charge injection layer. Even if the layer is formed, the effect of electron transfer due to the tunnel effect is exerted, so that it is possible to prevent image deterioration such as black spots in a non-development portion during reversal development using negatively charged toner.

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram schematically showing a basic configuration of an image forming apparatus according to the present invention.

As shown in FIG. 1, an image forming apparatus 1 according to the present invention includes a latent image carrier 2 on which an electrostatic latent image is formed, and a latent image carrier 2 that comes into contact with the latent image carrier 2. A writing device 3 for writing an electrostatic latent image of a negative polarity on the developing device 4 and a developing device 4 for reversal developing the electrostatic latent image on the latent image carrier 2 with a negatively charged developer carried and conveyed by a developer carrier 4a And a transfer device 6 for transferring the developer image on the latent image carrier 2 developed by the developing device 4 onto a transfer material 5 such as paper, and transferring the charge remaining on the latent image carrier 2 after transfer. At least a static eliminator 7 for eliminating static is provided.
In the following description, all the latent image carriers 2 are described as being grounded, but this is for convenience of explanation, and the present invention is limited to the case where the latent image carrier 2 is grounded. is not.

FIG. 2A is a diagram for explaining a basic process of image formation in the image forming apparatus 1 of the present invention, in which a dielectric layer is formed on a substrate made of a conductive material as a latent image carrier 2. A multilayer latent image carrier having a charge injection layer laminated thereon is used. Further, a charge eliminating roller 7b is used as the charge eliminating device 7. The writing electrode 3b of the writing device 3 comes into contact with the charge injection layer, which is the surface layer of the latent image carrier, and negatively charges the non-image portion. Developer carrier 4a of developing device 4
Has a (-) DC bias voltage applied to it,
The developer carrier 4 a is configured to convey the negatively charged developer 8 toward the latent image carrier 2. Incidentally, a bias voltage in which an alternating current is superimposed on a direct current (-) can be applied to the developer carrier 4a. Further, an AC bias voltage is applied to the charge eliminating roller 7b.

In this image forming process, the charge removing roller 7b is in contact with the charge injection layer, and the charge of the latent image carrier is removed by the charge removal roller 7b, and the charge injection layer surface is removed from the charge of 0V. After being brought into a uniform charge state close to the latent image carrier 2 by the writing electrode 3b of the writing device 3,
The upper non-image portion is (-) charged, and an electrostatic latent image is written on the latent image carrier. Then, the negatively charged developer 8 conveyed by the developer carrier 4a of the developing device 4 adheres to the (−) non-charged image portion near 0 V on the latent image carrier, and the electrostatic latent image is reversely developed. You.

In the present invention, the latent image carrier is replaced with a multilayer latent image carrier having a dielectric layer and a charge injection layer laminated on a conductive layer. A photoconductor in which layers are stacked may be used. An image forming process using a photoconductor will be described with reference to FIG. In FIG. 2B, a static elimination lamp 7 a is used as the static eliminator 7 together with the photoconductor 2. Further, the writing electrode 3 of the writing device 3
“b” contacts the photoconductor 2 and charges the non-image portion of the photoconductor 2 (−). Further, a bias voltage in which an alternating current is superimposed on a direct current (−) is applied to the developer carrier 4 a of the developing device 4, and the developer carrier 4 a applies the negatively charged developer 8 to the photoconductor 2. To be transported to The developer carrier 4a may be applied with a (-) DC only bias voltage.

In the image forming process of this example, the charge on the surface of the photosensitive member 2 is removed by the charge removing lamp 7a, and the surface of the photosensitive member 2 is set to a uniform charge state close to 0 V where the charge is removed. The non-image portion on the photoconductor 2 is (-) charged by the writing electrode 3b of the loading device 3, and an electrostatic latent image is written on the photoconductor 2. Then, the negatively charged developer 8 conveyed by the developer carrying member 4a of the developing device 4 adheres to the (-) uncharged image portion near 0 V on the photoreceptor 2, and the electrostatic latent image is reversely developed. You.

In the present invention, as described above,
Although a photoconductor may be used as the latent image carrier, hereinafter, a dielectric layer on a substrate made of a conductive material as the latent image carrier,
A description will be mainly given of a case where a multilayer latent image carrier in which a charge injection layer is laminated is used.

FIG. 3 is a view for explaining a configuration of a contact portion between the writing electrode 3b and the latent image carrier 2, and FIG.
FIG. 3 is a perspective view for explaining an arrangement relationship between the writing electrode 3b and the latent image carrier 2, and FIG. 3B is a perspective view of the writing electrode 3b and the latent image carrier viewed from the rotation axis direction of the latent image carrier 3. It is an enlarged view of the contact state with 2. FIG. 4 is an enlarged view of the contact state between the writing electrode 3 b and the latent image carrier 2 as viewed from the rotation direction of the latent image carrier 3.

As shown in FIGS. 3A and 3B, in the image forming apparatus of the present invention, the writing device 3 includes a writing electrode 3a.
Is brought into contact with the surface of the latent image carrier 2 rotating in the direction of the arrow, and the writing electrode, which is driven and controlled by the driver 11, mainly performs charge injection and imparts charges to the latent image carrier. is there. Further, as shown in FIG. 3B, the latent image carrier 2 has a dielectric layer 2 on a base material 2c made of a conductive material.
d, a multilayer latent image carrier on which the charge injection layer 2b is laminated. The contact portion between the writing device and the latent image carrier is formed by contact between the plurality of writing electrodes and the charge injection layer of the latent image carrier, and as shown in FIG. May be formed by the plurality of electrodes 3b arranged in the rotation axis direction of the latent image carrier and the separating member 3c arranged between the plurality of electrodes 3b. Good.

The base material 3a of the writing device 3 supports the writing electrode 3b and is, for example, a silicon rubber plate (work function: 5.26 eV), an ethylene propylene copolymer rubber plate (EPDM, 5.23 eV), or the like. Rubber plate, polyethylene terephthalate plate, etc. have a high volume resistivity of 10 ¹⁰ Ω · cm or more, and are relatively soft and have a JISA hardness of 10
It is preferable to use a 50 ° flexible substrate, which enables the writing electrode to be lightly pressed onto the charge injection layer of the latent image carrier and brought into contact with a weak elastic restoring force due to the bending of the substrate 3a. Things.

In the image forming apparatus of the present invention, the pressing force of the writing electrode against the latent image carrier rotating at the predetermined speed v is not more than 15 N at a width of 300 mm, that is, not more than 0.05 N / mm, preferably linear pressure. Is 0.005 to 0.0
5 N / mm, more preferably 0.01 to 0.03 N /
mm, so that the charge injection can be performed stably. However, from the viewpoint of abrasion, it is desirable to reduce the linear pressure as much as possible while maintaining the state of keeping the contact stable.

As the write electrode material, for example, titanium (3.57 eV), zinc (4.33 eV), iron (4.6)
0eV), copper (5.02eV), Ni (5.22e
V), platinum (5.63 eV), and the like, which are appropriately selected in relation to the work function of the charge injection layer described later.

As a method of providing a writing electrode on a base material,
A concave portion corresponding to the write electrode shape is formed on the surface of the base material by a method such as etching, and a write electrode material is vacuum-deposited on the concave portion,
It may be formed by filling by a method such as plating,
A metal foil may be stuck on a base material, or a metal film may be formed by laminating by vapor deposition, plating, or the like, and then patterned into an electrode shape. The film is formed with a thickness of 3 μm to 20 μm. Good. The volume resistance at the writing electrode is 10 ^-1
Ω · cm or less, and the surface of the write electrode 3b may be covered with a thin protective layer that easily tunnels electrons so long as the above-mentioned function is not impaired.

Further, a separating member 3c may be provided between the writing electrodes, if necessary, to make contact with the surface of the latent image carrier together with the writing electrodes. When the write electrode is embedded in the surface of the base material, the spacing member is made of the same material as the base material, but it is necessary to select a material whose work function is similar to the work function of the charge injection layer described later. In the case where a separating member is provided between the write electrodes provided on the flat base material, the work function of the charge injection layer described later is less than 0.15, preferably a work function having almost no difference. For example, the same material as the charge injection layer described later is used as an example, and is formed by coating between electrodes. The potential for injecting charges from the write electrode into the charge injection layer and charging it is several hundred volts, and the difference in work function between the separating member and the charge injection layer is 0.15.
If it is less than the above, charging due to friction can hardly occur, and even if it occurs, it can be ignored.

Next, as shown in FIG. 3B, the latent image carrier 2 is made of a conductive material having a volume resistance of 10 ^-1 Ω · cm or less, such as aluminum, and is grounded in a cylindrical shape. Material 2c and dielectric layer 2 formed on the outer periphery of substrate 2c
d, the charge injection layer 2b.

The dielectric layer 2d is made of a polyester resin such as polyethylene terephthalate, a polycarbonate resin, a polystyrene resin, a fluororesin, a cellulose resin, a vinyl chloride resin, a polyurethane resin, an acrylic resin, an epoxy resin, a silicone resin, an alkyd resin, a melamine resin,
Examples of phenolic resin, polyamide resin, vinyl chloride-vinyl acetate copolymer resin alone, or two or more polymer alloys, etc., are formed by coating on a base material or by sticking a film-like material. Formed, film thickness 5 to 2
It is good to be 00 μm, preferably 5 to 50 μm. 5μ
If it is thinner than m, it will not function as a dielectric layer. The relative dielectric constant (ε) of the dielectric is 1 to 10, preferably 2 to
8

The charge injection layer 2b is preferably formed from (1) a resin in which the above-mentioned dielectric layer is mixed and dispersed with a conductive material, and (2) a conductive polymer material.

In the case of (1), the resin may be a solvent-soluble resin such as polyester resin, polycarbonate resin, fluorine resin, polyurethane resin, acrylic resin, epoxy resin, alkyd resin, melamine resin, phenol resin and polyamide resin. The use of a paint binder makes it easy to disperse and mix the conductive material, and the charge injection layer can be formed only by the drying step of the coating layer.

When a resin other than a paint resin, such as a polystyrene resin, a cellulose resin, a vinyl chloride resin, a silicone resin, or a vinyl chloride-vinyl acetate copolymer resin, is used, it is melt-kneaded with a conductive material. Therefore, it is necessary to uniformly disperse the conductive material in the resin, to melt-extrude the resin, or to form a film for sticking. To uniformly disperse the conductive material in a highly viscous resin even at high temperatures, a long-term kneading operation with the addition of a surfactant is required,
It has the advantage of high bonding between resins and excellent abrasion resistance, and is suitable as a binder for a charge injection layer in contact with a writing electrode.

As the conductive material to be mixed, zinc oxide, tin oxide, antimony oxide, titanium oxide, barium sulfide, aluminum oxide, strontium titanate, and magnesium oxide are doped with antimony, indium, carbon, and the like, respectively. Processed, and
Copper, aluminum, nickel, stainless steel, metal particles and metal fibers such as iron, other, carbon black, silicon carbide, silicon oxide, silicon nitride, carbon fibers, perchlorate and the like, as a volume average particle size, It is only necessary that the distance be smaller than the distance between the electrode pitches.
It is as follows.

Among the above conductive materials, the surface tension of the metal oxide subjected to the conductivity treatment is about 100 dyne / cm.
The metal particles are about 1000 dyne / cm, but the surface tension of the binder resin is about 40 dyne / cm,
Conductive metal oxides having a surface tension value close to the surface tension of the binder resin have higher compatibility with the binder resin and are more suitable for uniform dispersion. In addition, a dispersant or the like is appropriately added.

When a paint binder is used, examples of the solvent include alcohols such as methanol and ethanol, ketones such as acetone and methyl ethyl ketone, dimethyl sulfoxide, hexane and toluene.

The conductive material is mixed at a ratio of 5 to 100 parts by weight, preferably 20 to 80 parts by weight with respect to 100 parts by weight of the binder resin to form a coating solution.
The charge injection layer may be formed by coating on the dielectric layer, or may be formed into a film and then pasted on the dielectric layer.

Further, the charge injection layer may be formed from a conductive polymer material. Examples of the conductive polymer material include polyacetylene, poly-p-phenylene, poly-p-phenylene sulfide, polypyrrole, polychenylene, and polyaniline alone or a conductive polymer material such as A
Examples thereof include those doped with sF ₅ , I ₂ , BF _{4, and the} like.

The thickness of the charge injection layer is from 0.01 μm to
100 μm, preferably 0.1 μm to 20 μm,
When the film thickness is large, the lateral charge of the latent image is undesirably diffused.
The volume resistance of the charge injection layer is 10 ³ to 10 ¹⁵ Ω · c.
m, preferably in the range of 10 ⁷ to 10 ¹² Ω · cm. If the volume resistance is low, the diffusion of the latent image charge is likely to occur,
In particular, it easily occurs under high temperature and high humidity. On the other hand, if the volume resistance is too high, the function as the charge injection layer is reduced. When the latent image carrier is a photoconductor made of a photoconductive layer, the charge injection layer needs to be transparent, so that a transparent conductive material such as tin oxide is used as the conductive material. .

The work function of the surface of the charge injection layer is 4-6.
In the present invention, the work function of the charge injection layer is set to be larger than the work function of the write electrode in relation to the work function of the write electrode. There is a potential barrier that makes it easier for electrons to flow in the direction from the write electrode side to the charge injection layer. For this reason, the work function of the charge injection layer is preferably at least 0.15 eV or more, preferably 0.3 eV or more than the work function of the write electrode, whereby an image forming apparatus corresponding to high speed can be obtained. In addition, an electrostatic latent image corresponding to the writing voltage can be stably applied to the latent image carrier, and an image forming apparatus having excellent resolution can be provided.

In the image forming apparatus of the present invention, for example, when the work function of the charge injection layer is 5.18 eV, the work function of the write electrode may be 5.18 eV or less. For example, titanium (3.57 eV), zinc (4.33 eV), iron (4.60 eV), copper (5.02)
A write electrode formed from a material such as eV) may be used.

The image forming apparatus of the present invention may be a method using an intermediate transfer member. In this case, the toner image on the latent image carrier is once transferred to a belt-shaped or roll-shaped intermediate transfer body, and then transferred to a transfer material such as paper using a transfer roll or the like. . Further, as the negatively charged toner, resin,
Examples include a pulverized toner, a suspension polymerization toner, and an emulsion polymerization toner, which are obtained by melt-kneading a pigment, a charge control agent, a release agent, and the like, and pulverizing and classifying. Alternatively, color toners of cyan, yellow, magenta, and black may be used. In this case, after developing the electrostatic latent image on the latent image carrier, each color is sequentially transferred onto the intermediate transfer body, and the intermediate transfer is performed. It is preferable that the color toner formed on the body is collectively transferred to the receiving paper.

[0044]

The present invention will be described below in detail with reference to examples. The work function (φ) defined in the image apparatus of the present invention is a surface analysis apparatus (AC-1 manufactured by Riken Keiki Co., Ltd.).
Is measured by

A polycarbonate resin film (specific permittivity: 2.7, volume resistivity: 1) was placed on an aluminum tube having an outer diameter of 28.86 mm.
× 10 ¹⁵ Ω · cm, film thickness 70 μm) by a coating method to form a dielectric film, and 100 parts by weight of a polyamide resin (FR-104, manufactured by Lead Co., Ltd.) on the dielectric film. Conductive titanium oxide TiO ₂ (manufactured by Titanium Industry Co., Ltd.
FC-300, 33 parts by weight of a volume average particle diameter of 20 nm) and a dispersion having a solid content of 33% using ethanol were applied, and then dried at 150 ° C. for 3 hours using a vacuum drier. A 1 μm charge injection layer was formed to form a latent image carrier.

The volume resistance of the charge injection layer is increased by Hiresta IP.
(Mitsubishi Yuka Co., Ltd.), 7.6 × 10
^{It was 10} Ω · cm, and the work function was 5.18 eV.

On the other hand, a 1 mm thick silicon rubber plate (JISA hardness 30) was used as a base material in the writing device shown in FIG.
After forming a concave portion (depth: 10 μm) in the shape of a write electrode on the surface having a work function of 5.26 eV), the concave portion is filled with a titanium film (work function: 3.57 eV) by plating to create a writing device. did.

The obtained latent image carrier and the writing device are incorporated in an image forming apparatus shown in FIG. 2A, the rotation speed of the latent image carrier is set to 20 cm / s, and the writing electrode is connected to a line. The latent image carrier was brought into contact with the charge injection layer surface at a pressure of 0.02 N / mm, and a voltage of -300 V was applied to the writing electrode to form an electrostatic latent image on the latent image carrier. The charge injection layer surface potential is -3
00V, and the injection efficiency was excellent.

Next, a polyester resin, copper phthalocyanine, a pyridinyl salt, and a polypropylene wax are melted, kneaded, and pulverized as a negatively charged developer, and then classified, and fine particles of silica are added to mother particles having a volume average particle diameter of 7.5 μm. Using the toner obtained by external addition, the electrostatic latent image on the latent image carrier was reversely developed and an image was formed on the transfer receiving paper. And no toner adhered to the non-image area.

[0050]

According to the image forming method of the present invention, an electrostatic latent image corresponding to a writing voltage can be stably applied to a latent image carrier even at high speeds, and an image with excellent resolution can be formed. It can be a device.

[Brief description of the drawings]

FIG. 1 is a diagram schematically showing a basic configuration of an image forming apparatus according to the present invention.

FIG. 2 is a diagram illustrating a basic process of image formation in the image forming apparatus of the present invention.

3A and 3B are diagrams illustrating a contact state between a writing electrode of a writing device and a latent image carrier, and FIG. 3A is a perspective view illustrating an arrangement relationship between the writing electrode and the latent image carrier. (B) is an enlarged view of the contact state between the writing electrode and the latent image carrier viewed from the rotation axis direction of the latent image carrier.

FIG. 4 is a diagram showing a contact state between a writing electrode of a writing device and a latent image carrier, and is an enlargement of a contact state between the writing electrode and the latent image carrier viewed from the rotation direction of the latent image carrier. FIG.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 image forming apparatus 2 latent image carrier 3 writing apparatus 3
a: base material, 3b: writing electrode, 4: developing device, 5: transfer material, 6: transfer device, 7: static eliminator, 8: developer

Continuation of front page (72) Inventor Kenjiro Yoshioka 3-5-5 Yamato, Suwa-shi, Nagano Seiko-Epson Corporation F-term (reference) 2C162 AE21 AE44 AE47 AE61 AE74 AE84 EA20 2H029 AA06 AB03 AC05 AD05 2H068 GA01 GA02

Claims (4)

[Claims] 1. A latent image carrier on which an electrostatic latent image is formed, a writing device having a writing electrode for writing the electrostatic latent image on the latent image carrier, and a negatively charged electrostatic latent image. An image forming apparatus for forming an electrostatic latent image by bringing the writing electrode into contact with the latent image carrier in a rotating direction thereof, the image forming apparatus comprising: An image forming apparatus, wherein a charge injection layer is provided on a surface of a body, and a work function of the surface of the charge injection layer is larger than a work function of a surface of the writing electrode. 2. The image forming apparatus according to claim 1, wherein the difference between the work function of the surface of the charge injection layer and the work function of the surface of the electrode is 0.15 eV or more. 3. A contact portion of a writing device with a latent image carrier is composed of a plurality of electrodes arranged in a rotation axis direction of the latent image carrier and a separating member arranged between the plurality of electrodes. Wherein the difference between the work function of the surface of the separating member and the work function of the surface of the charge injection layer is less than 0.15 eV.
Alternatively, the image forming apparatus according to claim 2. 4. A contact portion of a writing device with a latent image carrier has a linear pressure of 0.05 N /
The image forming apparatus according to any one of claims 1 to 3, wherein the image is pressed at a distance of not more than mm.