JP2002225332A - Imaging apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an imaging apparatus in which stability can be enhanced in the writing position control of a latent image while lowering the applying voltage. SOLUTION: An image carrier 2 has a multilayer structure of a dielectric layer 2b formed on the outer circumference of a conductive basic material 2a and a low resistance charge injection layer 2c formed on the outer circumference of the dielectric layer 2b. A writing electrode 3b touches the charge injection layer 2c and performs writing of an electrostatic latent image dominantly by injecting charges between the writing electrode 3b and the charge injection layer 2c. An applying voltage is lowered significantly through charge injection. Since environmental effect is eliminated at the time of writing through charge injection, the latent image is written with no positional distortion and stability is enhanced in the writing position control of the latent image. Furthermore, charges can be injected effectively between the writing electrode and the dielectric layer 2b by suppressing lateral leak of charges at the charge injection layer 2c. Consequently, the latent image can be written on the image carrier with high accuracy by charge injection.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention belongs to the technical field of an image forming apparatus for forming an image by writing an electrostatic latent image on an image carrier by a writing electrode of a writing device. The present invention belongs to the technical field of an image forming apparatus in which an electrostatic latent image is written on an image carrier by charge injection between the image carrier and the image carrier.

[0002]

2. Description of the Related Art An image forming apparatus in which an electrode is used as a conventional electrostatic latent image writing device and an electrostatic latent image is written on the surface of an image carrier by using the electrode has been proposed in Japanese Patent Laid-Open No. 59-33969. ing. The image forming apparatus disclosed in this publication has a large number of pin electrodes, and a recording drum is formed of a metal drum having a surface coated with a dielectric film, and is arranged in a non-contact manner with the recording drum. All the pin electrodes are driven between the pin electrodes and the recording drum to cause all pin discharges, and a solid black latent image for one line is formed on the surface of the recording drum.

As another conventional electrostatic latent image writing apparatus, an image forming apparatus for writing an electrostatic latent image on the surface of a recording medium by an ion flow method has been proposed in Japanese Patent Laid-Open No. 6-8510. The image forming apparatus disclosed in this publication includes a corona charger, and controls an ion flow of corona ions generated from a wire of the corona charger by an aperture electrode. A latent image is formed on the surface of the recording medium.

[0004]

However, in each of the image forming apparatuses disclosed in these publications, the charged voltage is extremely high because the charged writing is performed by using the discharge. In addition, since the carriers are ions due to discharge, ionization due to discharge varies depending on the environment such as temperature and humidity, so that the position of the latent image to be written is distorted.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to improve the stability of controlling the writing position of a latent image and to reduce the applied voltage. It is to provide a device.

[0006]

In order to solve this problem, the present invention is directed to an image carrier on which an electrostatic latent image is formed, and a writing method for writing the electrostatic latent image on the image carrier. An image forming apparatus, wherein the writing device writes the electrostatic latent image on the image carrier by the writing device. The image carrier has a conductive base to which a low voltage is supplied as an absolute value, and a conductive base; A dielectric layer formed of a material and a charge injection layer of a low resistance layer formed on the dielectric layer to form a multilayer structure, wherein the write electrode contacts the charge injection layer and the write Writing of the electrostatic latent image by charge injection between the electrode and the charge injection layer is predominantly performed. It is characterized in that.

Further, the invention of claim 2 is characterized in that the surface resistance of the charge injection layer is set such that the electric resistance in the vertical direction <the electric resistance in the horizontal direction. Further, claim 3
In the invention, the thickness of the charge injection layer is set to 1 μm or less. Furthermore, the invention of claim 4 is characterized in that the charge injection layer is formed in a conductive sea-island structure in which a large number of the charge injection layers are independently dispersed on the surface layer of the dielectric layer.

[0008]

In the image forming apparatus of the present invention having the above-described structure, the image carrier is formed by forming the dielectric layer and the dielectric layer on the conductive substrate to which the low voltage is supplied in absolute value. A multilayer structure (two layers) is formed from the low resistance layer and the charge injection layer. Further, the writing electrode comes into contact with the charge injection layer, and the writing of the electrostatic latent image by the charge injection between the writing electrode and the charge injection layer is predominantly performed. Therefore, the applied voltage is significantly lower than in the conventional charged writing by discharge.

In writing by charge injection, since the carrier is an electric charge, there is no influence from the environment such as temperature and humidity, so that the position of the latent image to be written is not distorted, and the writing position of the latent image is controlled. Stability is improved.

Further, since the image carrier is formed in a multilayer structure of the dielectric layer and the charge injection layer, the charge leakage in the charge injection layer is suppressed, and the write electrode, the charge injection layer and The charge is effectively injected between the two, and the image carrier can be reliably charged or discharged. Therefore, it becomes possible to write the electrostatic latent image on the image carrier with high accuracy by charge injection.

In particular, according to the second aspect of the present invention, since the surface resistance of the charge injection layer is set so that the resistance in the vertical direction is smaller than the resistance in the horizontal direction, leakage of charges in the charge injection layer in the horizontal direction is further ensured. , And the latent image writing by charge injection is performed with higher accuracy. Therefore, an image with good contrast can be formed.

According to the third aspect of the present invention, since the thickness of the charge injection layer is set to 1 μm or less, the potential contrast of the electrostatic latent image is further increased. Therefore, the latent image writing accuracy is further improved.

Further, in the invention of claim 4, a large number of charge injection layers are formed on the surface of the dielectric layer independently of each other to form a conductive sea-island structure. Therefore, by setting a large number of charge injection layers, which are local conductive portions, smaller than the contact area of the writing electrode and the contact area of the toner, a stable latent image can be formed.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a view schematically showing a basic configuration of an example of an embodiment of an image forming apparatus according to the present invention, and FIG. 2 is a partial perspective view partially showing a basic configuration of the image forming apparatus shown in FIG. .

As shown in FIG. 1, an image forming apparatus 1 according to the present invention includes an image carrier 2 on which an electrostatic latent image and a developer image are formed, and an image carrier 2 that comes into contact with the image carrier 2. A developing device 4 for writing an electrostatic latent image on the image carrier 2 with a developer carried and conveyed by a developing roller 4a; And a transfer device 6 for transferring the developer image on the image carrier 2 onto a transfer material 5 such as paper by a transfer roller 6a.

As shown in FIGS. 2 and 3, the image carrier 2
Is located near the center, is made of a conductive material such as aluminum, and is grounded; a dielectric layer 2b formed on the outer periphery of the conductive substrate 2a; It is formed in a drum shape from the charge injection layer 2c of the low resistance layer formed on the outer periphery of the layer 2b. That is, the two-layer structure of the dielectric layer 2b and the charge injection layer 2c is
It is formed so as to surround the outer periphery of a. Note that the image carrier 2 may be formed in a belt shape.

Each writing electrode 3b of the writing device 3 is in contact with the charge injection layer 2c, and charge injection is predominantly performed between the writing electrode 3b and the charge injection layer 2c. It has become. This charge injection is performed when the charge is
b, the charge is injected from the charge injection unit 2c to the write electrode 3b;
Needless to say, in the former case, the image carrier 1 is charged, and in the latter case, the image carrier 1 is discharged.

The description will be made assuming that the conductive substrate 2a of the image carrier 2 is grounded. However, this is for convenience of description, and the present invention is based on the assumption that the conductive substrate 2a of the image carrier 2 is grounded. However, as described later, it is also possible to apply a voltage whose absolute value is smaller than the absolute value of the predetermined voltage V ₀ applied at the time of writing.

Since the dielectric layer 2b plays a role in the inside of the capacitor and has a function of placing a charge on the image carrier 2 in a spot, the electric resistance is preferably set to 10 ¹⁵ Ω or less. As a material used for the dielectric layer 2b, polyester resin, polycarbonate resin, polyethylene resin, fluororesin, cellulose, vinyl chloride resin, polyurethane resin, acrylic resin, epoxy resin,
Resins such as silicone resin, alkyd resin, vinyl chloride-vinyl acetate copolymer resin, and polyamide resin (nylon) can be used.

On the other hand, as a material of the charge injection layer 2c, a material having a resistance region having a maximum electric resistance of about 10 ¹⁰ Ω or less is used. In this case, if the electric resistance of the charge injection layer 2c is too large, the writing is affected by a time constant delay and a latent image writing failure occurs. Therefore, the electric resistance of the charge injection layer 2c decreases as the process speed increases. Is more preferred.

As the simplest method of forming the charge injection layer 2c, a method in which conductive particles / conductive fillers and the like are dispersed in a suitable amount in a binder resin and applied to the surface of the dielectric layer 2b can be considered. Generally, as a material used for the binder resin, polyester resin, polycarbonate resin, polystyrene resin, fluororesin, cellulose,
Resins such as vinyl chloride resin, polyurethane resin, acrylic resin, epoxy resin, silicone resin, alkyd resin, vinyl chloride-vinyl acetate copolymer resin, and polyamide resin (nylon) can be used. Cu, A as a material used for the conductive filler
l, metal powders such as Ni, ZnO, tin oxide, antimony oxide, metal oxide powders such as TiO ₂ (electroconductively treated), polyacetylene doped with iodine to form a polymer complex, and polythiofin with iodine A conductive polymer powder such as a polymer complex obtained by doping a polymer complex, a polymer complex obtained by doping iodine into polypyrrole, or a combination of appropriate materials can be used. In this case, the resistance is adjusted by setting the content of the conductive fine particles / conductive filler to 10 to 100% wt.

Further, the charge injection layer 2c may be formed on the surface of the dielectric layer 2b in such a manner that a large number of charge injection layers 2c have a conductive islands-in-sea structure which are independent of each other. For example, as shown in FIGS. 4A and 4B, the upper surface of the dielectric layer 2b is formed in a rough jagged shape, and the jagged concave portion is filled with a conductive material to form a dielectric material such as a sea. It is also possible to form a large number of charge injection layers 2c, such as a large number of islands, composed of local conductive portions independent of each other on the upper surface of the layer 2b. Further, as shown in FIGS. 5A and 5B, for example, conductive fine particles and the like are dispersed in an alkaline liquid in an insulating binder layer 2d (part of the dielectric layer 2b) of the surface layer of the alkali-soluble image carrier. The charge injection layer 2c can also be formed by spraying the liquid at an equal interval to a position determined by an inkjet method. In the case of such a sea-island structure, the charge injection layer 2c can be formed by a method other than the above-described method using a binder dispersion or an inkjet method.
Can be produced.

Further, regardless of the above-described manufacturing method, the charge injection layer 2c has a surface resistance in the vertical direction (that is, the radial direction of the latent image carrier) <the horizontal direction (that is, the radial direction of the latent image carrier). It is preferable to use a structure (a structure having anisotropy of resistance) having an electric resistance of a direction perpendicular to the above. This is because the charge injected from the write electrode 3b is effectively injected in the vertical direction, and the leakage is hardly performed in the horizontal direction. In this case, the difference between the resistance in the horizontal direction and the resistance in the vertical direction (in other words, the ratio of the resistance in the horizontal direction / the resistance in the vertical direction) is preferably larger. 10 ⁵
It is preferable to set the relationship as follows. This relationship is realized by reducing the thickness of the charge injection layer 2c, even when the charge injection layer 2c does not exhibit resistance anisotropy. Further, as shown in Table 1, when the charge injection layer 2c is uniformly dispersed in the binder dispersion system, the thinner the charge injection layer 2c is, the more the resistance anisotropy is realized.

[0024]

[Table 1]

The values shown in Table 1 indicate that the binder resin is polyamide resin (trade name: FR-10, manufactured by Lead Co., Ltd.).
4%, conductive titanium oxide (trade name: EC-300, manufactured by Titanium Industry Co., Ltd.) as a conductive filler at a weight ratio of 1: 1.
3 shows the results of resistance measurement after mixing at a ratio of 3 and ultrasonically dispersing with an ethanol solvent, coating an Al substrate with 1 to 100 μm. In that case, the resistance was measured using a Hiresta manufactured by Mitsubishi Yuka Corporation.

Then, the volume resistivity and the surface resistivity are measured with the high rester, and the longitudinal resistance and the horizontal resistance which can be calculated from these values, the film thickness and the electrode area of the high rester can be obtained. Results, roughly as described in Table 1 above
It turned out to be as follows. Also, from experiments to be described later, in the case of the same material, in order to improve the accuracy of writing a latent image, it is advantageous that the thickness of the charge injection layer 2c is thin, and in particular, the thickness is 1 μm or less. preferable.

As shown in FIG. 2, the writing device 3
(Abbreviation of Flexible Print Circuit, hereinafter referred to as FPC)
Alternatively, a flexible base material 3a such as PET (abbreviation for polyethylene terephthalate, hereinafter referred to as PET) or the like having a high insulating property, relatively soft and elastic, and supported by the base material 3a and weak by bending of the base material 3a A plurality of writing electrodes 3b which are lightly pressed onto the image carrier 2 by an elastic restoring force to contact and write an electrostatic latent image, and a writing electrode 3b supported on a base material 3a;
11 for controlling the operation of the writing electrode 3 and the writing electrode 3 of the substrate 3a
An end opposite to the end b is provided with a fixing portion 3c fixed to the image forming apparatus main body (not shown).

The substrate 3a is formed in a rectangular plate shape having a length substantially equal to the axial length of the charge injection layer 2c of the image carrier 2 in the axial direction of the image carrier 2. The substrate 3a is provided so as to extend in the same direction as the rotation direction (clockwise direction indicated by the arrow) of the image carrier 2 from the left side in FIG. Meanwhile, the substrate 3a is reversed from the right side in FIG.
May also be provided so as to extend in the direction of rotation of.

The material of the writing electrode 3b is required to be conductive, in which case the electric resistance is set to 10 ¹⁰ Ω or less. If the electric resistance is too large, the above-described charge injection layer 2
As in the case of c, since latent image writing failure occurs due to the influence of the time constant delay in the writing electrode 3b, it is preferable that the electric resistance is lower as the process speed is higher. In an experiment to be described later, an Al writing electrode and a writing electrode having an electrical resistance of 10 ⁶ Ω in which a fluorine resin was coated on the Al writing electrode were used. Since latent image writing can be performed, a writing electrode having an electric resistance of 10 ⁶ Ω or less is preferable.

FIG. 6 shows that a plurality of writing electrodes 3b are
FIG. 5 is a diagram showing an arrangement pattern when the arrangement is performed in the axial direction of FIG. As shown in FIG. 6, the arrangement pattern of the plurality of writing electrodes 3b is such that each writing electrode 3b is formed in a circular shape and the image carrier 2 is formed.
(In the vertical direction in FIG. 6).
In this case, the write electrodes 3b are arranged in two rows and in a staggered manner, and although not clearly shown in FIG. 6, one of the write electrodes 3b adjacent to each other in the first and second rows is arranged. The units are arranged so that the portions overlap each other in a direction orthogonal to the axial direction of the image carrier 2 of the image carrier 2. In such an arrangement pattern of the electrodes 3, the charge injection layer 2 of the image carrier 2 is formed.
The non-charged portion which is not written by the charge injection from the write electrode 3b is not formed on the surface c, and the charge injection layer 2 of the image carrier 2 is not formed.
The entire surface of the c surface can be charged or gradually transmitted.

A predetermined number of drivers 11 are provided on the base 3a so as to extend in the axial direction of the image carrier 2. In this example, a plurality of sets in which a predetermined number of adjacent write electrodes 3b in the first row and a predetermined number of write electrodes 3b in the second row are connected to one driver 11 are formed by a plurality of shafts of the image carrier 2. It is arranged in the direction. In this case, each driver 11 is formed on the base material 3a and is electrically connected by a conductive pattern 9 made of, for example, copper (Cu) foil or the like having a thin flat plate shape with a rectangular cross section. 11 and the corresponding write electrodes 3b are electrically connected by the conductive pattern 9 formed on the base material 3a. These conductive patterns 9 can be formed by a conventional thin film pattern forming method such as etching. At the time of writing a latent image, line data, a write timing signal, and high-voltage power are supplied to each driver 11 from above in FIG. 6, and each driver 11 further supplies a corresponding write electrode 3b. Is supplied with a predetermined voltage V ₀ on the high voltage (in absolute value) side and a ground voltage V ₁ on the low voltage (in absolute value) side.

FIG. 7 is a diagram showing a switching circuit for switching and connecting predetermined voltage V ₀ and ground voltage V ₁ to write electrode 3b. As shown in FIG. 7, each write electrode 3b
Are the corresponding high-voltage switches (High Voltage
Switch; HVSW) 15, and these high-voltage switches 15 are respectively connected to the corresponding write electrodes 3.
b is switched between a predetermined voltage V ₀ on the high voltage (in absolute value) side and a ground voltage V ₁ on the low voltage (in absolute value) side. An image writing control signal from a shift register (SR) 16 is input to each high voltage switch 15.
The image signal stored in the buffer 17 and the clock signal from the clock 18 are input to the shift register 16. And shift register 1
The image writing control signal from 6 is input to each high voltage switch 15 by the AND circuit 19 based on the writing timing signal from the encoder 20. The above-described driver 11 that switches and controls the supply voltage to each write electrode 3b by each high voltage switch 15 and AND circuit 19 is configured.

FIG. 8 shows a state in which each high-voltage switch 15 of each writing electrode 3b is selectively switched to a predetermined voltage V0 or a ground voltage V1, respectively. FIG. 8A shows the voltage state of each electrode. FIG. 3B is a diagram illustrating a developer image when normal development is performed in the voltage state of FIG. 3A, and FIG. 3C is a diagram illustrating a developer image when reverse development is performed in the voltage state of FIG. .

For example, as shown in FIG.
It is assumed that the -1st, nth, n + 1th, and n + 2th write electrodes 3b are in the voltage state shown in FIG. Therefore, when the electrostatic latent image is written on the image carrier 2 by each electrode in such a voltage state, and this electrostatic latent image is developed by regular development, the developer (or toner) 8 deposited on the predetermined voltage V ₀ parts of the body 2, the developer image as shown by hatched (shaded) in FIG. 8 (b) (or a toner image) is obtained. Further, performs writing of an electrostatic latent image in the same manner, when developing the electrostatic latent image by reversal development, the developer 8 is deposited on the ground voltages V ₁ portion of the image carrier 2, FIG. 8
A developer image as shown by hatching in (c) is obtained.

In the image forming apparatus 1 thus configured, charge is injected from the writing electrode 3b of the writing device 3 in contact with the image carrier 2 into the charge injection layer 2c of the image carrier 2. Then, writing of a latent image by charge injection is performed predominantly, and an electrostatic latent image is written on the image carrier 2. And
The electrostatic latent image on the image carrier 2 is used as a developing roller 4a of the developing device 4.
Is developed by the developer conveyed by the transfer device 6, and the developer image is transferred to the transfer material 5 by the transfer device 6.

(Embodiment) Next, specific embodiments (1) and (2) of the image carrier 2 formed in a two-layer structure from the dielectric layer 2b and the charge injection layer 2c, which are characteristic parts of the present invention. 2) will be described. The binder resin, conductive filler, and solvent used for the charge injection layer 2c in Examples (1) and (2) are all the same, and are shown in Table 2.

[0037]

[Table 2]

As shown in Table 2, in each of Examples (1) and (2), a polyamide resin (manufactured by Lead Co., Ltd., trade name: FR-104) was used as a binder resin, and a conductive filler was used. Conductive titanium oxide (trade name: EC-300, manufactured by Titanium Industry Co., Ltd.), and ethanol as a solvent.

The ratio (gr.) Of the polyamide resin as the binder resin to the conductive titanium oxide (c-TiO ₂ ) as the conductive filler, the content (%) of the conductive titanium oxide, and the coating film thickness (μm) were determined. Table 3 shows each of Examples (1) and (2).

[0040]

[Table 3]

As shown in Table 3, in Example (1), the ratio of the polyamide resin to the conductive titanium oxide was 5.0 / 2.5.
(Gr.), The conductive titanium oxide content is set to 33.0 (%), and the coating film thickness is set to 1 (μm). In this embodiment (1), the volume resistance Rv (Ω) is 1 .3 × 10
⁹ (Ω) and the surface resistance Rs (Ω) is 7.6 × 10
¹³ (Ω). In Example (2), the ratio between the polyamide resin and the conductive titanium oxide was 5.0 / 2.5 (g).
r.), the content of conductive titanium oxide is set to 33.0 (%), and the coating film thickness is set to 10 (μm). In this example (2), Rv is 1.3 × 10 ¹⁰ ( Ω) and R
s was 7.6 × 10 ¹² (Ω).

The conductive substrate 2a of the image carrier 2
Using a 30 (mm) aluminum drum, PET is applied to this aluminum drum at a thickness of 100 μm to form a dielectric layer 2b. Further, on this PET, the materials shown in Table 2 are applied in the ratio shown in Table 3. A coating liquid prepared by mixing and uniformly dispersed by ultrasonic dispersion is applied by a wire bar. afterwards,
The image carrier 2 was produced by forming the charge injection layer 2c on the conductive substrate 2a while maintaining the temperature in a vacuum dryer at 150 ° C. for 3 hours.

The write electrodes 3b are made of Al and Cu, respectively.
Set to φ50μm, 50μm away from the axis of image carrier 2
It was provided in parallel in the direction. And the high voltage (absolute value) side
Pressure V ₀Is set to -400V and the low pressure (absolute value) side
Voltage V₁Is set to 0 V, and the high
By turning on / off the voltage switch 15, these voltages are
The supply is switched to each writing electrode 3b. The image bearer
The peripheral speed of the holding body 2 is set to 30 mm / sec.

In this manner, when all the electrodes were turned on and the toner image was developed by reversal development,
A better image was obtained using the image carrier 2 of Example (1) than using the image carrier 2 of Example (2).

In the embodiments (1) and (2), each of the writing portion where the writing of -400 V is performed at the developing position and the non-writing portion where the writing of the closest portion is not performed. When the surface potential was measured by a surface potential sensor, as shown in FIGS. 9 and 10, the voltage of the writing portion was -400 V in both of the embodiments (1) and (2). The voltage of the embedded portion was −30 V in Example (1) and −120 V in Example (2). That is, the embodiment (1)
Is smaller in voltage leakage in the horizontal axis, that is, in the axial direction of the image carrier 2, than in the embodiment (2).

Therefore, when the charge injection layer 2c of the resin uniform dispersion system is used as in the image forming apparatus 1 of this embodiment,
It was found that if the material of the charge injection layer 2c was the same, the smaller the film thickness, the better the latent image reproducibility. In other words, as long as the charge injection layer 2c has substantially the same electric resistance, it is preferable that the thickness of the charge injection layer 2c is small because the potential contrast of the electrostatic latent image can be increased. The thickness of the layer 2c is preferably set to 1 μm or less.

However, in the image formation, a toner image is formed in connection with factors other than the latent image writing, such as the toner charge amount and the developing conditions. It goes without saying that an image can be formed by the image forming apparatus 1 of the embodiment (2) simply because the image can be formed more stably than the embodiment (2).

As described above, according to the image forming apparatus 1 of this example, the image carrier 2 is provided on the outer periphery of the conductive base material 2a to which a low voltage is supplied in absolute value, by the dielectric layer 2b and the dielectric layer 2b. Layer 2b
And a charge injection layer 2c of a low resistance layer formed on the outer periphery of the semiconductor device, and the write electrode 3b contacts the charge injection layer 2c to form a charge between the write electrode 3b and the charge injection layer 2c. Since the writing of the electrostatic latent image by the injection is predominantly performed, the applied voltage can be significantly reduced as compared with the conventional charged writing by the discharge. Therefore, it is possible to effectively use a 300V high-voltage driver currently on the market.

Also, in writing by charge injection, since the carrier is a charge, there is no influence by the environment such as temperature and humidity, so that the position of the latent image to be written is not distorted and the writing position control of the latent image is not performed. Stability can be improved.

Further, since the image carrier 2 has a two-layer structure of the dielectric layer 2b and the charge injection layer 2c, the charge injection layer 2c
At the same time, the lateral leakage of charge is suppressed,
Charges can be effectively injected between the charge injection layer 2b and the charge injection layer 2c, and charging or discharging can be performed. Therefore, it becomes possible to write the electrostatic latent image on the image carrier with high accuracy by charge injection. In particular, since the surface resistance of the charge injection layer 2c is set so that the resistance in the vertical direction is smaller than the resistance in the horizontal direction, the leakage of charges in the charge injection layer 2c in the horizontal direction can be more reliably suppressed, and the precision can be further improved. A latent image can be written by charge injection. Therefore, an image with good contrast can be formed. In particular, by setting the thickness of the charge injection layer 2c to 1 μm, the potential contrast of the electrostatic latent image can be further increased, and the accuracy of writing the latent image can be further improved.

Further, since a large number of charge injection layers 2c are formed on the surface of the dielectric layer 2b so as to be dispersed independently of each other to form a conductive sea-island structure, a large number of charge injection layers 2c which are local conductive portions are formed. By setting the contact area of the writing electrode 3b smaller than the contact area of the toner and the contact area of the toner, a stable latent image can be formed.

The image carrier 2 may be a photosensitive member, in which case the charge injection layer 2c is set so as to have light transmittance. Further, the image forming apparatus 1 of this example is different from the image forming system of negative development and normal development as in the above-described embodiments (1) and (2), in addition to the image formation system of positive development and normal development. And an image forming method of reversal development with negative charging.
Further, the image forming apparatus of the present invention can be applied to an image forming apparatus in which a latent image is written by removing charge from a positively or negatively charged image carrier 2 by a writing electrode 3b.

FIG. 11 shows an application example of the image forming apparatus of the present invention.
It is a figure which shows typically. As shown in FIG.
Image forming apparatus 1 includes black, cyan, magenta,
And yellow image forming apparatuses 1_K, 1_C, 1_M, 1_YIs transcribed
These are arranged in tandem in this order from the upstream side in the moving direction of the material 5.
Has been established. Image forming apparatus 1 for each color_K, 1 _C, 1_M, 1_Yof
The arrangement order can be set to any order.
Each image forming apparatus 1_K, 1_C, 1_M, 1_YAre respectively
It is the same as the image forming apparatus 1 and the image carrier 2_K, 2_C,
2_M, 2_Y, Writing device 3_K, 3_C, 3_M, 3_Y, Developing device 4_K, 4_C,
4_M, 4_YAnd transfer device 6_K, 6_C, 6_M, 6_YHas
You.

The image forming apparatus of this embodiment thus configured
In the apparatus 1, first, a black K image forming apparatus 1_KTo
The black K image carrier uniform charge control device 7
Image carrier 2_KAfter the surface of the
Place 3_KWrite electrode 3b_KIn the case of
The electrostatic latent image of K is the image carrier 2_KWhen written on the surface of
In both cases, the black K electrostatic latent image is_KIn
Image bearing member 2_KBlack K developer image on the surface
It is formed. This image carrier 2_KTop black K developer
Image transfer device 6_KIs transferred to the transfer material 5 supplied.
As a result, a black K developer image is formed on the transfer material 5. Next
The cyan C image forming apparatus 1_CAt the cyan C
Image carrier 2 by the image carrier uniform charge control device 7_Cof
After the surface is uniformly charged, the writing device 3_CWriting electrode 3
b_CAnd an electrostatic latent image of cyan C is formed mainly by charge injection.
Carrier 2_CWritten on the surface of this cyan
C electrostatic latent image is developed by developing device 4_CImage carrier 2 developed with_Cof
A cyan C developer image is formed on the surface. This image carrier
2_CThe upper cyan C developer image is transferred to the transfer device 6_CSupplied by
The transfer material 5 on which the black K developer image has been formed.
Is transferred to form a cyan C developer image on the transfer material 5.
It is. Similarly, the magenta M image forming apparatus 1 _MIn
Writing device 3_MWrite electrode 3b_MImage carrier 2 by_MWhat
Writing and developing device for magenta M electrostatic latent image_MElectrostatic latent
Image development and transfer device 6_MMagenta on transfer material 5
After the superposition transfer of the M developer image is performed, the yellow Y
Image forming apparatus 1 _YWriting device 3_YWrite electrode 3b_Y
Image carrier 2 by_YWriting of a yellow Y electrostatic latent image to the
Developing device 4_YFor developing and transferring an electrostatic latent image of_YTurn
The transfer of the yellow Y developer image to the transfer material 5 is performed, and the transfer is performed.
A full-color image in which developer images of each color are color-matched to the copying material 5
A developer image is formed. Thus, the image forming apparatus of each color
1_K, 1_C, 1_M, 1_YIs a full-color tandem
In the image forming apparatus, the image forming apparatus of the present invention is used.
This allows for a smaller and simpler configuration.
Can be.

FIG. 12 shows another example of the image forming apparatus of the present invention.
It is a figure which shows an example of use typically. In the example shown in FIG.
Image forming apparatus 1_K, 1_C, 1_M, 1_YWas placed in tandem
In the image forming apparatus 1, each image forming apparatus 1_K, 1_C, 1_M, 1_Y
Image carrier 2_K, 2_C, 2_M, 2_YDeveloper of each color formed on
An image is formed in each image forming apparatus 1_K, 1_C, 1_M, 1_YTransfer to transfer material 5 every time
The image forming apparatus 1 of this example is
Then, as shown in FIG._K, 2_C, 2_M,
2_YThe developer image of each color formed on the surface was once intermediately transferred
Thereafter, the image is transferred to the transfer material 5. Sand
That is, in the image forming apparatus 1 of this example, the image of the example shown in FIG.
An intermediate transfer device 24 is provided in the image forming apparatus 1. This
Of the intermediate transfer device 25 in the form of an endless belt
The intermediate transfer body 25 has two rollers 26,
It is stretched between 27 and is driven by one roller.
And rotate counterclockwise. And
Each image forming device is arranged along a linear portion of the intermediate transfer body 25.
Place 1_K, 1_C, 1 _M, 1_YAnd the roller
One transfer device 6 is provided at position 27. this
Another configuration of the example image forming apparatus 1 is an image forming apparatus shown in FIG.
The same as the forming apparatus 1.

In the image forming apparatus 1 of this embodiment configured as described above, the image carriers 2 _K , 2 _C , 2 _M , and 2 _Y of the respective colors are provided on the image carriers 2 _K , 2 _C , 2 _M , and 2 _Y similarly to the image forming apparatus 1 of the example shown in FIG. Are formed, and the developer images of the respective colors are color-matched in the same manner as when the developer images of these colors are transferred to the intermediate transfer body 25 on the transfer material 5 in the example shown in FIG. Overprinted. The developer image of each color intermediately transferred to the intermediate transfer body 25 is transferred to the transfer material 5 by the transfer device 6, and the transfer material 5
, A full-color developer image is formed. Other image forming operations of the image forming apparatus 1 of this example are the same as those of the image forming apparatus 1 of the example shown in FIG. As described above, the image forming apparatus of the present invention is also used in a full-color image forming apparatus including the intermediate transfer device 24 and the tandem arrangement of the image forming devices 1 _K , 1 _C , 1 _M , and 1 _{Y of} the respective colors. Thus, the configuration can be made smaller and simpler.

[0057]

As is apparent from the above description, according to the image forming apparatus of the present invention, the image bearing member is provided with the dielectric layer and the dielectric layer on the conductive substrate to which a low voltage is supplied in absolute value. A charge injection layer of a low resistance layer formed on the body layer is formed into a multilayer structure, and a write electrode is brought into contact with the charge injection layer to form an electrostatic charge by charge injection between the write electrode and the charge injection layer. Since the writing of the latent image is predominantly performed, the applied voltage can be greatly reduced as compared with the conventional charged writing by discharge.

In the writing by charge injection, since the carrier is an electric charge, there is no influence by the environment such as temperature and humidity, so that the position of the latent image to be written is not distorted and the writing position of the latent image is controlled. Stability can be improved.

Further, since the image carrier is formed in a two-layer structure of a dielectric layer and a charge injection layer, the leakage of charges in the charge injection layer in the horizontal direction is suppressed, and the write electrode and the charge injection layer are formed. This makes it possible to inject the charges effectively between the first and second steps, and to reliably charge or remove the charges on the image carrier. Therefore, it becomes possible to write the electrostatic latent image on the image carrier with high accuracy by charge injection.

In particular, according to the second aspect of the present invention, by setting the surface resistance of the charge injection layer such that the resistance in the vertical direction is smaller than the resistance in the horizontal direction, leakage of charges in the charge injection layer in the horizontal direction is further ensured. And the latent image writing by charge injection can be performed with higher accuracy. Therefore, an image with good contrast can be obtained. According to the third aspect of the present invention, the thickness of the charge injection layer is 1 μm.
m, the potential contrast of the electrostatic latent image can be further increased. Therefore, the latent image writing accuracy can be further improved.

Further, according to the fourth aspect of the present invention, since a large number of charge injection layers are formed on the surface of the dielectric layer independently of each other to form a conductive sea-island structure, they are locally conductive portions. By setting a large number of charge injection layers smaller than the contact area of the writing electrode and the contact area of the toner, a stable latent image can be formed.

[Brief description of the drawings]

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

FIG. 2 is a partial perspective view partially showing a basic configuration of the image forming apparatus shown in FIG.

FIG. 3 is a partially enlarged view showing the image carrier shown in FIG. 1 with a write electrode partially enlarged;

4A and 4B show a modified example of the image carrier in the image forming apparatus of the present invention, wherein FIG. 4A is a plan view, and FIG. 4B is a cross-sectional view taken along a line in the left-right direction of FIG.

5A and 5B show another modified example of the image carrier in the image forming apparatus of the present invention, wherein FIG. 5A is a plan view and FIG. 5B is a cross-sectional view taken along the left-right direction of FIG.

FIG. 6 is a diagram showing an arrangement pattern and wiring patterns of electrodes and drivers.

FIG. 7 is a diagram showing a switching circuit for switching and connecting a predetermined voltage V ₀ and a ground voltage V ₁ to electrodes.

FIG. 8 shows a state when each high voltage switch of each electrode is selectively controlled to be switched to a predetermined voltage V0 or a ground voltage V1, respectively. FIG. 8 (a) is a diagram showing a voltage state of each electrode.
FIG. 6B is a diagram illustrating a developer image when normal development is performed in the voltage state of FIG. 7A, and FIG. 7C is a diagram illustrating a developer image when reverse development is performed in the voltage state of FIG.

FIG. 9 is a diagram schematically showing a specific example (1) of a writing electrode and an image carrier in the image forming apparatus of the present invention, and showing a surface potential of the image carrier at the time of writing.

FIG. 10 is a diagram schematically showing a specific embodiment (2) of a writing electrode and an image carrier in the image forming apparatus of the present invention, and showing a surface potential of the image carrier at the time of writing.

FIG. 11 is a diagram schematically showing an application example of the image forming apparatus of the present invention.

FIG. 12 is a diagram schematically showing another application example of the image forming apparatus of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Image forming apparatus, 2 ... Image carrier, 2a ... Conductive base material, 2b ... Dielectric layer, 2c ... Charge injection layer, 2d ... Insulating binder layer, 3 ... Writing device, 3a ... Base material, 3b: writing electrode, 4: developing device, 5: transfer material, 6: transfer device, 8 ...
Developer (or toner)

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Mikio Furumizu 3-3-5 Yamato, Suwa-shi, Nagano Seiko-Epson Corporation F-term (reference) 2C162 AE21 AE62 EA19 EA20 2H029 AA06 AB03 AB10 AD04

Claims (4)

[Claims] 1. An image carrier on which an electrostatic latent image is formed, and a writing device for writing the electrostatic latent image on the image carrier, wherein the writing device writes the electrostatic latent image on the image carrier. An image forming apparatus adapted to write an electrostatic latent image, wherein the writing device includes a writing electrode for writing the electrostatic latent image on the image carrier, and a flexible base material supporting the writing electrode. The image carrier has a conductive base to which a low voltage is supplied in absolute value, and a dielectric layer formed on the conductive base and a low resistance formed on the dielectric layer. And a charge injection layer, the write electrode is in contact with the charge injection layer, and the electrostatic latent image is formed by charge injection between the write electrode and the charge injection layer. An image forming apparatus wherein writing is performed dominantly. 2. The image forming apparatus according to claim 1, wherein the surface resistance of the charge injection layer is set such that electric resistance in a vertical direction <electric resistance in a horizontal direction. 3. The image forming apparatus according to claim 1, wherein the thickness of the charge injection layer is set to 1 μm or less. 4. The charge injection layer according to claim 1, wherein a plurality of said charge injection layers are formed on a surface of said dielectric layer in a conductive sea-island structure in which each of said charge injection layers is independently dispersed. The image forming apparatus according to any one of the above.