JPH1020646A - Developing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device forming an excellent image by removing dust raised from a recording medium. SOLUTION: In this developing device 4; a toner supply roller 45 is provided in a developing container 41 so that it may contact and slide on a developing roller 40 and the rollers 45 and 40 can mutually rotate, and the toner is supplied from the roller 45 to the roller 40. Nip width between the rollers 40 and 45 is set to >=1mm and both rollers are rotated in a counter direction at the nip position.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing device used in an image forming apparatus such as a printer, a copying machine, a facsimile or the like using an a-Si drum.

[0002]

2. Description of the Related Art Conventionally, an electrophotographic apparatus based on the so-called Carlson process, which is a kind of image forming apparatus, is well-known. It is necessary to apply a high voltage of 8 KV or more to the wire, and as a result, ozone and nitrogen oxides and ammonium salts, which are discharge products thereof, are generated, and these are adsorbed on the surface of the photoreceptor, so that image flow is likely to occur.

In order to solve such a drawback, a roller configured to contact a conductive roller on a photosensitive drum and apply a DC voltage to the conductive roller to perform contact charging of the photosensitive drum in a dark place. Although there is a charging method, even in this charging method, since there is a minute wedge-shaped gap between the photosensitive drum and the charging roller, a slight discharge phenomenon occurs in that portion, and the generation of ozone is recognized. However, the disadvantages described above cannot always be eliminated.

On the other hand, in recent years, there has been a photosensitive drum used in an electrophotographic apparatus which uses an a-Si drum in order to improve durability and achieve free maintenance.
Si has a high hygroscopicity compared to an organic semiconductor, so that the image flow is likely to occur in the a-Si drum more frequently.
A sheet heater or other heating element is disposed on the back side of the photosensitive drum, and the photosensitive drum is heated to prevent the occurrence of the image deletion.

However, providing a heater requires heat control means and the like, which not only complicates the configuration, but also makes the system complicated when a heater is used especially in miniaturization and personalization of copiers and printers. turn into.
In addition, a certain time is required for raising the temperature of the heater, and the time from when the power is turned on to when printing is performed (warm-up time) is long, which requires power consumption. When the photoconductor is heated, the TG temperature (glass transition temperature) of the toner is increased.
Since the temperature is raised to a value close to the temperature, toner adheres to the surface of the photoconductor. Various problems occur.

Further, even in a state in which image deletion does not occur, in this type of electrophotographic apparatus, toner adheres to a developing area of an electrostatic latent image formed on a photosensitive member in a developing step, and a toner adheres to a non-developing area. In order to prevent adhesion, the photosensitive member surface potential is set to 400 V or more in the charging step, and the difference between the high potential portions of the electrostatic latent image formed in the exposure step is set to 400 V.
As described above, the developing potential was required to be 200 V or more. Therefore, a photoconductive material having a charging ability of 400 V or more is required for the photoreceptor, and there are great restrictions on material selection and film thickness setting.

Further, a-Si tends to cause a so-called “fogging” phenomenon in which toner adheres to a white background. This is a phenomenon in which the toner in the apparatus adheres to the surface of the photoreceptor due to an image force or the like. The image power of the toner is greatly affected by the relative permittivity of the photosensitive layer, and the higher the relative permittivity, the higher the image power. This relative dielectric constant is usually 3 to 3 for an organic photoreceptor.
Since it is 3.5, and a-Si is as large as about 10 to 12, a-fogging phenomenon easily occurs in a-Si.

Conventionally, a pulverized toner has been used. This pulverized toner is obtained by cooling a kneaded material obtained by mixing small particles such as a resin, a colorant and a charge control agent, and then coarsely pulverized by a hammer mill, a cutter mill or the like, and further jet-milled. 8 to 1 depending on the size
It is made by finely pulverizing it to about 5 μm. Although it is relatively easy to make, it is made into an irregular shape with irregularities, and the charge tends to concentrate on the protrusions, and the surface of the photoreceptor may come into contact with a plurality of protrusions for one particle. In some cases, the image power increases.

Under such circumstances, the applicant of the present invention used an a-Si drum prior to the present application, and in particular, uniformly charged the photoconductor including a discharge phenomenon, such as a corona discharger, a charging roller, and a charging brush. An application has been filed for the purpose of providing an electrophotographic apparatus capable of forming a clear image without causing image deletion and a 'fogging' phenomenon even in an electrophotographic apparatus which has performed the above. That is, the thickness of the surface layer of the electrophotographic photoreceptor obtained by laminating and covering the photoconductive layer and the surface layer on the substrate is 25 μm.
m, the surface potential of the photoreceptor is set to about 400 V or less, and a developing roller with a development potential set to about 150 V or less is brought into rolling contact with the surface layer. Roller volume resistivity is 3 × 10
An electrophotographic apparatus is disclosed which is configured to be set to ⁷ Ωcm or less and to develop a latent image of the photoconductor while forming a thin layer of toner particles formed by a polymerization method on the developing roller. ing. In the apparatus according to this application, the developing unit also serves as a cleaning unit, and performs cleaning while shaving the surface of the photoreceptor to some extent, and at the same time, enables development, thereby preventing an image deletion phenomenon under a special environment.

[0010]

However, if paper is used as the recording medium to be transferred from the photoconductor and the above-described apparatus has been used for a long period of time, when the paper is transferred from the photoconductor to the recording paper, If a minute portion peels off and becomes dust, and enters into the developer, the dust adheres to the image together with the development, and a good image cannot be formed.

The present invention has been made in view of the above circumstances, and has as its object to provide a developing device that removes dust generated from a recording medium and forms a good image. Another object of the present invention is to provide a clear image that does not cause image deletion and a 'fogging' phenomenon while considering simplification and safety of a configuration used in an image forming apparatus using an a-Si drum. An object of the present invention is to provide a developing device that can be formed.

[0012]

According to the present invention, a toner supply roller is provided in a developing container so as to be rotatable with each other by contacting and rubbing with the developing roller, and to supply toner from the toner supplying roller to the developing roller. The developing device is configured so that both rollers rotate in the counter direction while the nip width between the developing roller and the toner supply roller is set to 1 mm or more.

With such a configuration, in FIG.
The toner supply roller 4 supplies toner to the developing roller 40.
5A, the rollers 40 and 45A are rotated in the same rotation direction (counterclockwise) about their respective rotation axes, and the contact amount (nip width) between the rollers is reduced. Since it is set to 1 mm or more, when the developing roller 40 and the supply roller 45A are rotated counterclockwise around their respective rotation axes,
Both rollers at the nip position rotate in the counter direction, and the residual toner 51 containing the peeling powder of the recording medium and the photoconductor powder obtained by polishing the surface of the photoconductor 1 is adhered to the surface of the developing roller 40. In this case, as shown by reference numeral 53, the toner is collected by a supply roller 45A rotating in a direction opposite to the developing roller 40 in a nip area where both rollers affect each other.

Therefore, the residual toner is removed from the surface of the photoreceptor 40, new toner 50 is supplied, the toner charge amount is reduced, and the image quality is reduced due to the reduced toner layer thickness.
Good image formation can be performed without causing image deletion and without requiring excessive torque on the supply roller 45A. As a result, the developing roller 4
The nip width between 0 and the supply roller 45A can be set to 1 mm or more, desirably 1 to 5.0 mm.

Further, as a result, the peeling powder of the recording paper is collected in the developing container together with the residual toner by the developing roller, and a good image forming apparatus can be provided.

It is also an effective means of the present invention that the developing container is provided with a powder removing means for removing the peeling powder peeled off from the recording medium on which the image on the photosensitive member is transferred. . In this way, the supply roller 45A absorbs paper dust in the developing container 41 as shown in FIG.
By providing a powder removing means for removing paper dust by the cleaning member 43 as shown in FIG. 3, during maintenance, the suction device or the developing container is replaced.
If the residual toner aggregate containing the release powder is removed from the inside of the developing container by long-term use, a special cleaning means is additionally provided, and a good image is always obtained without increasing the number of parts. Can be provided.

In addition, the peeling powder is configured to be removed by the toner supply roller, and the potential applied to the developing roller and the supply roller is variable.
It is also an effective means of the present invention to configure the apparatus so as to correspond to the charging polarity of the release powder. At that time, a predetermined potential is applied to the developing roller and the toner supply roller, and at the time of development, the absolute value of the potential applied to the toner supply roller side from the development roller is increased.
At the time of non-development, the absolute value of the potential applied to the toner supply roller side from the developing roller is lower, or the absolute value of the potential applied to the developing roller side and the absolute value of the potential applied to the toner supply roller side are equal. It is desirable.

If the surface of the supply roller is formed by a sponge or the like that absorbs the release powder generated by printing a predetermined number of sheets or more, the supply roller absorbs the release powder, and after the predetermined number of prints, the supply roller absorbs the release powder. By exchanging the supply roller, it is possible to provide an image forming apparatus having a developing device that can perform favorable image formation and that can easily perform maintenance.

Further, since the recording paper is charged to either positive or negative depending on the type of paper, it is necessary to match the polarity of the charging polarity of the release powder separated from the recording medium.
At the time of development, since it is necessary to supply toner to the developing roller side, the absolute value of the potential on the supply roller side is increased to move the toner from the supply roller side to the developing roller side. At this time, if the separating powder is negatively charged and the developing roller and the supply roller are positively charged, the potential on the supply side is high, and thus the powder is collected from the development roller to the supply roller side. If the powder is positively charged, it will not be recovered.

Therefore, while the latent image on the photosensitive member for one page is being developed by the developing roller, it is not collected by the supply roller. When the development of one page is completed and it is not necessary to increase the absolute value of the potential on the supply roller side, the absolute value of the potential on the supply roller side is inverted and reduced. As a result, the positive release powder moves from the developing roller side to the supply roller side. When the developing roller side and the supply roller side have the same absolute value of the potential, the developing roller and the supply roller are rubbed, and thus are scraped and fall into the developing container. In this way, by reversing the potential direction between the developing roller and the supply roller during development and during non-development, paper dust can be collected.

Further, according to the present invention, since the latent image of the photosensitive member is developed while forming a thin layer of toner particles formed by a polymerization method on a developing roller, electric charges are stored in spherical toner particles. It is uniformly charged, and has a point contact with the surface of the photoreceptor, so that there are few points of contact with one toner particle, the image power is small, and the 'fogging' phenomenon is small.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be illustratively described in detail with reference to the drawings. However, unless otherwise specified, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention, but are merely illustrative examples. Not just.

FIG. 1 shows an embodiment of an image forming apparatus to which the present invention is applied. Exposure is performed along a rotating direction around an a-Si photosensitive drum (photosensitive body) 1 rotating clockwise in FIG. Optical system including the LED head 2 and the SELFOC lens 3, a developing unit 4, a transfer roller 5, a static elimination lamp 7,
And a charging unit 8.

Next, each component will be described.
As shown in A, the photosensitive drum 1 has a conductive support 1a.
A photoconductive layer 1b and a surface layer 1c are laminated and formed thereon, a carrier injection blocking layer 1e is provided between the conductive support 1a and the photoconductive layer 1b, and a photoconductive layer 1b and the surface layer 1c are formed.
A transition layer 1f is interposed between them. The support 1a is generally made of an aluminum cylindrical body.
It is formed of a metal material such as S, Ti, Ni, Au, Ag, etc., an inorganic material such as glass having a conductive film adhered on the surface, or a transparent resin such as epoxy, and has a thickness of 3 mm in this embodiment.
To set the outer diameter to 30 mm and 254 in the axial direction.
An aluminum cylindrical body having a length of mm is used.

The carrier injection blocking layer 1e is a photoconductive layer 1
Various materials are used depending on the material of b. When an a-Si-based material is used for the photoconductive layer 1b, it is preferable to use the a-Si-based carrier injection blocking layer 1e.

The a-Si-based photoconductive layer 1b is formed into a film by a glow discharge decomposition method, a sputtering method, an ECR method, an evaporation method, or the like. In forming the film, an element for terminating a dangling bond, for example, (H) And halogen 5 to 40w
It is better to contain t%. That is, a-
A photoconductor made of Si: H is used. When the developing bias is positive, non-doped or Va group elements are contained in order to increase the mobility of electrons. When the developing bias is negative, the movement of holes is performed. In order to increase the degree, it is preferable to include a group IIIa element. If necessary, elements such as C, O, and N may be contained in order to obtain desired characteristics such as electric characteristics such as dark conductivity and photoconductivity, and optical band gap.

The total thickness of the photoconductive layer 1b is:
The thickness is preferably about 3 to 50 μm in order to ensure necessary charging and insulation withstand voltage, absorb exposed light, and suppress the above-described residual potential.

The surface layer 1c has a thickness of 25 μm.
Below, glow discharge decomposition method, sputtering method, ECR
A film is formed by a method, a vapor deposition method, etc., and the element ratio composition formula (a-
When expressed as Si _{1 −X} C _X : H), x is 0.95 ≦
It is composed of hydroxide amorphous silicon carbide having x <1 and a dynamic indentation hardness of the outermost surface (free surface layer) of 50 to 200 Kgf / mm ² , and particularly has a resistance value of 10 ¹² to 10 ^13. Set to a resistance value in the Ω · cm range. The surface layer 1c is formed from the photoconductive layer 1b from the outermost surface side.
The hardness is set so as to gradually increase as it goes to the far side of the side.

In order to form a gradient of the hardness as described above (a gradient such that the hardness gradually increases toward the back side of the photoconductive layer 1b from the outermost surface side), for example, the surface layer 1c is glowed. When a film is formed by the discharge decomposition method, the ratio of the C-containing gas to the Si-containing gas in the source gas is gradually increased with time, the gas pressure during film formation is gradually increased, and the hydrogen gas as the source gas is used. , The discharge power is gradually reduced, and the substrate temperature of the aluminum cylindrical drum is gradually lowered.

Further, between the photoconductive layer 1b and the surface layer 1c,
It is preferable to provide a transition layer 1f in which the C content in a-SiC: H is smaller than the C content in the surface layer 1c. Further, the C content of the transition layer 1f may be changed in the layer to have a gradient of the content. Such a transition layer 1
By providing f, the traveling of the photocarriers generated in the photoconductive layer 1b becomes smooth, the photosensitivity is high, the residual potential is low, and the image characteristics are good. The thickness of such a transition layer 1f is 1 μm or less, preferably 0.05 to
It is set in the range of 0.5 μm.

The exposure LED head 2 has an exposure wavelength of 6
A head array of 85 nm is used, and the head array is configured to perform a dynamic drive to divide the exposure into 64 bits × 40 times for each scanning line.

A developing unit 4A shown in FIG. 2 includes a developing container 40 containing a non-magnetic one-component toner, a developing roller 40 comprising an elastic body 42 made of an elastic material such as urethane rubber, and a toner to the roller 40. A developing blade 17 for regulating a layer thickness, a supply roller 45A for supplying toner to the developing roller 40, and the like;
The supply roller 45A, the developing blade 17, etc.
DC developing bias power supplies E1 (350V), E2 (350V),
3 (120 V) to perform development.

Since the outer periphery of the supply roller 45A is formed of a sponge which rotates in contact with the elastic body 42 of the developing roller 40, it is softer than the elastic body of the developing roller 40,
In addition, countless pores having a diameter smaller than the toner particle diameter and larger than the paper dust of the recording paper are formed. The supply roller 45A is connected to the developing roller 40 by a nip width 1.
mm or more.

In the developing unit 4A, as shown in FIG. 2, the supply roller 45A rotating counterclockwise is
Similarly, since the toner is in contact with and rubs against the developing roller 40 that rotates counterclockwise, new toner 50 is supplied to the developing roller 40 by the supply roller 45A, and the toner layer thickness is regulated by the developing blade 17 that regulates the toner layer thickness. 0.3mg /
is regulated in cm ² ~0.9mg / cm ^2, it is supplied to the photosensitive member 1.

On the other hand, the residual toner 49 of the toner not transferred to the recording paper 9 comes into contact with the elastic body 42 of the developing roller 40 again. Rotates rapidly, the residual toner 49 is scraped off by the elastic body 42 of the developing roller 40 as indicated by reference numeral 51, and new toner 48 develops the latent image on the surface of the photoconductor 1.

As indicated by reference numeral 51, the developing container 41
The remaining toner 52 that has not fallen to the lower portion of the inside and adheres to the developing roller 40 is removed by the supply roller 45A that rotates in the opposite direction to the developing roller 40 in a nip area where the developing roller 40 and the supply roller 45A affect each other. ,
As indicated by reference numeral 53, the developer is dropped and collected below the developing container 41.

At this time, the separating powder 56 separated from the recording paper 9 is negatively charged, and the developing roller 40 and the supply roller 4
If 5A is positively charged, the potential on the supply side is high during development, so that it is collected from the developing roller 40 to the supply roller 45A side, but if the peeling powder 56 is positively charged,
Not recovered.

Therefore, the separating powder 56 is not collected by the supply roller 45A while the latent image of the photosensitive member for one page is being developed by the developing roller 40. When the development of one page is completed and it is not necessary to increase the absolute value of the potential on the supply roller 45A side, the absolute value of the potential on the supply roller 45A side is inverted and reduced. As a result, the positively charged release powder 56 moves from the developing roller 40 side to the supply roller 45A side.

Since the isolating powder 56 is smaller than the particle size of the toner particles, it is taken into the fine pores in the sponge of the supply roller 45A. When the developing roller 40 and the supply roller 45A have the same absolute value of the potential,
Since the developing roller 40 and the supply roller 45A are rubbing each other, they are scraped off and fall into the developing container.

Since the recording paper is charged to either positive or negative depending on the type of paper, it is necessary to match both the positive and negative polarities of the charge of the peeled powder separated from the recording medium. In this embodiment, as described above, the potential of the developing roller and the supply roller is made variable, and the potential of the developing roller and the supply roller is inverted during development and during non-development. Since it is configured so as to cope with the problem, it is possible to collect the paper dust.

In this embodiment, the supply roller is formed with a sponge or the like that absorbs the release powder generated by printing a predetermined number or more of prints, and the supply roller absorbs the release powder to print the predetermined number of prints. By exchanging the supply roller after the above, it is possible to provide a developing device in which good image formation can be performed and maintenance is easy.

In this embodiment, the photosensitive member 1 and the developing roller 40
Is of a rubbing type, and if the resistance value is too low, the toner may be a polymerized toner and a high resistance of 10 ⁶ Ωcm or more or an insulating toner may be used in view of leakage. In the polymerized toner, at the stage of polymerizing a polymer from a monomer, toner particles are produced by incorporating a colorant, a charge control agent, and the like into the polymer particles, so that spherical particles are obtained, and the charges are uniformly charged on the spherical particles. Therefore, due to point contact with the surface of the photoreceptor, the number of contact points with respect to one particle is small and the image force is small.

The developing roller 40 is provided on the surface layer 1 of the photosensitive member 1.
c at a nip width of 1 mm or more (preferably 1 to 2 mm) and rotates in the same direction at the contact position, and the peripheral speed difference at that position is 1.1 times or more (preferably) the photosensitive member 1 Is from 0.3 mg / cm ^{2 to} 0.9 mg / toner layer thickness.
The speed is set to 1.1 to 6.0 times of cm ² . More preferably, the toner layer thickness is 0.7 mg.
/ Cm ² is set to a speed of 1.2 to 5.0 times.

The layer thickness of the toner particles is 0.3 mg / c.
m ^{2 to} 1.0 mg / cm ² , preferably 0.3 mg / c
m ² -0.9 mg / cm ² , more preferably 0.4 mg
/ Cm ^{2 to} 0.8 mg / cm ² . The transfer roller 5 uses a conductive roller to increase the transfer efficiency to the recording paper 9, applies a transfer bias having a polarity opposite to the charging potential of the toner, and uniformly presses the peripheral surface of the photosensitive drum 1. , And is rotatable in synchronization with the drum 1.

The charging unit 8 was uniformly charged on the photoreceptor by a well-known scorotron charger. In the figure, 81 is a corona discharge wire, 82 is a control grid, 8
3 is a discharge bias and 84 is a charge control bias.

In the first embodiment having the above-described structure, the charging device 8 has a charging control bias appropriately set between about 400 V. Therefore, by applying this high-voltage discharging bias, After the surface potential Vo of the photosensitive drum 1 is charged to the above set value, a predetermined latent image is exposed by the exposure head 2. Then, +
By applying 100 V and +350 V to the supply roller, the toner image formed by the polymerization method is attached to the latent image of the photoconductor, and transferred to a recording medium (recording paper) 9 inserted between the photoconductor 1 and the transfer roller 5. Let it. Then, during non-development, the residual toner is collected by applying -200 V to the developing roller and -350 V to the supply roller.

The recording paper 9 is sent out of a storage (not shown), inserted between the photosensitive member 1 and the transfer roller 5, and sent out to a fixing step (not shown) after the transfer. In this process, especially before and after including the transfer process, the paper dust is separated from the recording paper by pressure contact with a roller or the like.

On the other hand, in FIG. 2, the residual toner 49 of the toner not transferred to the recording paper 9 contacts the elastic body 42 of the developing roller 40 again including the paper dust of the recording paper 9. Since the peripheral speed of the developing roller 40 is higher than that of the photoconductor 1 at the contact position with the photoconductor 1, the developing roller 40
The residual toner 49 is scraped off by the elastic body 42 as indicated by reference numeral 51 and new toner 48 develops the latent image on the surface of the photoconductor 1.

The residual toner denoted by reference numeral 51 contains a small amount of photoreceptor powder obtained by polishing the surface of photoreceptor 1 together with paper dust. That is, the residual toner 51 is scraped off by the developing roller 40 and falls below the developing container 41, but may adhere to the surface of the developing roller 40 as indicated by reference numeral 52 and be transported. In the nip area where both rollers affect each other, the supply roller 45A rotates in the opposite direction to the developing roller 40, and is dropped and collected below the developing container 41 as indicated by reference numeral 53.

At this time, the separating powder 56 is smaller than the particle diameter of the toner particles, and thus is taken into the fine pores in the sponge of the supply roller 45A. On the other hand, the dropped residual toner 53 mixes with the new toner in the developing container 41, but is diluted because the amount is smaller than the amount of the new toner. Therefore, it is desirable that the residual toner 53 be returned to the inside of the developing container 41 and injected into the new toner near the entrance where the new toner is supplied and stirred.

Next, a second embodiment will be described. 3 is different from FIG. 2 in that the first embodiment shown in FIG.
Although a predetermined number (50,000 or more) of paper dust is absorbed by the sponge portion by the supply roller 45A whose outer peripheral portion is formed by a sponge portion, the second embodiment employs the supply roller 45A.
A point that a separate cleaning member 43 is used for the developing roller 40 without using a sponge for B, and the residual toner including paper dust is scraped off from the developing roller 40 by the member 43 and stored in the waste toner section in the developing container. .

The cleaning member 43 is formed of a conductive fiber such as polyester, acrylic, carbon-filled rayon, nylon, vinylon, or the like around the rotation axis or by winding the fiber to form a rotating roller. Are in contact with the surface of the developing roller 40, and are arranged to rotate in a direction opposite to the rotation direction of the developing roller 40 at the contact position.

In FIG. 3, the residual toner indicated by reference numeral 54 contains a small amount of photoreceptor powder obtained by polishing the surface of photoreceptor 1 together with paper dust. That is, the residual toner 54 is
Although the toner is scraped off by the developing roller 40 and falls below the developing container 41, there is a case where the toner adheres to the surface of the developing roller 40 as indicated by reference numeral 55 and is transported.
Are scraped off by the cleaning member 43 and
1 falls below.

The residual toner 55 is transferred to the wall 41 of the developing container.
b, the toner is not mixed with new toner in the developing container 41, and is transferred to a storage part (not shown). Thus, paper dust is eliminated, and a good image can be obtained.

Image formation is affected not only by the above-mentioned paper dust but also by the phenomenon of image deletion. Here, the cause of the image deletion will be described. As shown in FIG.
In the i photoreceptor, a photoconductive layer 1b and a surface layer 1c are generally laminated on a conductive substrate 1a made of an aluminum cylinder, and the surface layer 1c is formed of an α-SiC-based inorganic high-resistance or insulating material. To maintain the surface potential Vo and the latent image potential distribution on the photoconductive layer 1b.

Accordingly, discharge products such as nitrate ions and ammonium ions generated by corona discharge during the image forming process are adsorbed on the surface layer 1c, and they are deposited on the photoconductive layer 1b under a high temperature and high humidity environment. The latent image charge formed on the surface layer 1c moves toward the surface based on the surface potential Vo and the latent image potential distribution, and a charge flow, that is, an image flow occurs. It is also considered that the photoreceptor surface is oxidatively degraded by continuous printing and becomes hydrophilic, which is also a factor of image deletion.

Due to this image deletion phenomenon, the latent image charge flows around the latent image in the case where there is no image deletion, and "bleeds" on the image.
The phenomenon occurs. In contrast, in the present embodiment, the surface layer of the photoreceptor is formed of an a-Si layer, and the volume resistivity of the developing roller that is in contact with the surface layer can be set to 3 × 10 ⁷ Ωcm or less. Prevents excessive voltage drop in the roller layer, and has a synergistic effect with the low relative dielectric constant of the a-Si photoconductor,
Even if the surface potential of the photosensitive member and the developing potential of the developing roller are set low, a sufficient image density can be obtained. Further, since the developing roller rubs against the photoreceptor, the discharge product is scraped off, and image flow can be prevented, and good image formation can be performed.

As a result, in this embodiment, the surface potential of the photosensitive member is set to about 400 V or less, preferably 300 to 350 V, and the developing potential of the developing roller is set to about 15 V.
The voltage can be set to 0 V or less, preferably 80 to 120 V, whereby the thickness of the photoreceptor can be reduced to 25 μm or less, and an image forming apparatus having a low-cost developing device can be provided. In addition, by adopting such a configuration, it is possible to form an image without causing image deletion even in a state where a heater is not built in the base supporting the photoconductive layer 1b.

In the first embodiment shown in FIG. 2, the developing roller 40 is rubbed against the surface of the surface layer 1c of the photoreceptor 1, and the photosensitive drum 1 is provided with a peripheral speed difference. Since the surface layer of the body is configured to be developed, the toner can be collected in the developing container together with the development in the developing container 41, and the paper powder is absorbed by the supply roller. It is possible to reuse the residual toner that is not used for the toner.

The developing roller 40 is connected to the photosensitive member 1
The effective developing state of the developing roller 40 can be maintained by setting the nip width in contact with the developing roller to 1.5 to 2.0 mm. In this embodiment, the latent image of the photoconductor 1 is developed while forming a thin layer of toner particles formed by a polymerization method on the developing roller 40 in the above-described development. The spherical toner particles are uniformly charged, and due to point contact with the surface of the photoreceptor, there are few points of contact with one toner particle, the image power is small, and the 'fogging' phenomenon is small.

As described in detail above, according to the present embodiment, fogging or the like does not occur even when image formation is performed without using a heater. Thermistor for detecting the temperature, reduction of electrical components such as a heater control circuit based on the detected temperature from the thermistor and the circuit configuration are simplified, and since the heater is not used, a warm-up time is unnecessary,
The device start-up time can be greatly reduced.

[0062]

【Example】

Example (1) An a-Si photosensitive member having a surface layer having a thickness of 25 μm was prepared, and charging was performed using a scorotron method V0: 350.
V, development is a non-magnetic one-component system, and the developing roll is a conductive roller having a diameter of 18 mm and a volume specific resistance of 5 × 10 ⁶ Ω · c.
m, surface roughness 10 microns or less, development nip about 1 mm,
Developing linear speed 120mm / sec (Photoconductor linear speed 60mm / s
ec), the developing blade has a thickness of 1.3 mm and a resistance value of 1
0 ⁴ Ω · cm or less, supply roll diameter 12 mm, resistance value: 10 ⁴ Ω · cm or less, each bias value is a developing blade 350 V, a supply roller 350 V, and a toner is a polymerization method based on a styrene acrylic material. The transfer was set at a transfer current of 20 to 30 microamps by a roller method.

In the above condition setting, the developing roller and the supply roller are rotated in the same rotational direction to change the contact amount between the developing roller and the supply roller, and the toner layer thickness is 0.7 mg / c.
It was measured in m ² . Table 1 shows the results.

[0064]

[Table 1] From Table 1, when the nip amount is 0.5 mm or less, the charge amount of the toner decreases, the thickness of the toner layer decreases, and the nip amount decreases to 7.0 mm.
In, the rotational torque of the supply roller was large. Therefore, it can be seen that a good image density is obtained when the nip amount is 0.8 to 6.0 mm, preferably, 1.0 to 5.0 mm.

Example (2) The film thickness of the surface layer was 25 μm
A-Si photoreceptor is prepared and charged by scorotron method V
0: 350 V, non-magnetic one-component development for development, conductive roller diameter 18 mm with conductive roller, volume resistivity: 5 × 1
0 ⁶ Omega · cm, the surface roughness 10 microns or less, the developing nip of about 1 mm, developing linear speed 120 mm / sec (photoconductor linear velocity 6
0 mm / sec), the developing blade has a thickness of 1.3 mm,
Resistance value: 10 ⁴ Ω · cm or less, supply roll 12 m in diameter
m, resistance value: 10 ⁴ Ω · cm or less, nip with the developing roll about 1 mm, each bias value
Supply roller 350V, potential difference 2 between photoconductor and developing roller
20 V, the toner layer thickness is 0.7 mg / cm ² , and the toner is
Using a styrene-acrylic material produced by polymerization with an average particle size of 8 microns and a pulverized method, the transfer is performed by a roller method and the transfer current is 20-30.
Set to microamps.

Normal temperature and normal humidity (N / N) at a temperature of 20 ° C. and a humidity of 60%
N), the transfer efficiency of each toner was measured at a high temperature and a high humidity (L / L) of 33 ° C. and a humidity of 85%, and the results are shown in Table 2.

[0067]

[Table 2] From Table 2, it can be seen that the transfer efficiency of the polymerization toner is superior.

[0068] Example (3) of the surface layer, the element ratio composition formula _{(a-Si 1 - X C} X: H) when expressed as, x is from 0.9
5 ≦ x <1 and dynamic indentation hardness of the outermost surface is 3
An electrophotographic photoreceptor having a hardness of not more than 00 Kgf / mm ² , and having a higher hardness on the back side of the photoconductive layer side than the outermost surface side, and having a hardness gradually increasing toward the back side, is prepared.
Charging is a scorotron method V0: 300 to 350 V, developing is a non-magnetic one-component method, developing roller is 18 mm in diameter, resistance value is 10 ⁶ Ω · cm to 10 ⁷ Ω · cm, surface roughness is 10 μm or less, and developing nip is about 1 mm, the developing blade has a thickness of 1.3 mm, the resistance value is 10 ⁴ Ω · cm or less, the supply roll is 12 mm in diameter, the resistance value is 10 ⁴ Ω · cm or less, the nip with the developing roll is about 1 mm, and each bias value is , Developing roller 100V, developing blade 350V, supply roller 350
V. The toner used had a mean particle size of 8 microns by polymerization based on a styrene acrylic material, and the transfer was set at a transfer current of 20 to 30 microamps by a roller method.

After performing a running test at 5,000 sheets at room temperature under the above settings, the test was carried out under an environment of 33 ° C. and 85% humidity.
When the image was evaluated after being left for more than an hour, a good image without image deletion was obtained.

[0070]

As described above, according to the present invention, it is possible to provide a developing device for preventing a deterioration in image quality of an image due to a peeling powder of a recording medium. Also, in an image forming apparatus such as a charging roller and a charging brush, in which a photosensitive member is uniformly charged with a discharge phenomenon, a clear image can be formed without causing an image deletion or a 'fog' phenomenon. , A-S
An image forming apparatus using an i-drum has various remarkable effects, such as being able to form a clear image without causing image deletion or a 'fogging' phenomenon, while considering simplification of the configuration and safety.

[Brief description of the drawings]

FIG. 1 is an embodiment of an image forming apparatus to which the present invention is applied.

FIG. 2 is a configuration diagram showing a configuration of a first embodiment in a developing container.

FIG. 3 is a configuration diagram showing a configuration of a second embodiment in a developing container.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 photoreceptor drum 1 a conductive substrate 1 b photoconductive layer 1 c surface layer 2 exposure head 3 optical system 4 developing unit 8 charging device 40 developing roller 41 developing container 43 cleaning member 45 toner supply roller (45A, 45B)

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Keiji Itsukushima 704-19 Noshino, Tamaki-cho, Machi Prefecture Mie Prefecture Inside the Mie Tamaki Plant, Kyocera Corporation (72) Inventor Yoshio Ozawa 704-19 Noshino, Tamaki-cho, Tamaki-cho, Mie Prefecture Kyocera Corporation Mie Tamaki Factory

Claims (5)

[Claims] 1. A developing device in which a toner supply roller is provided in a developing container so as to be rotatable with each other by contacting and sliding with the developing roller, and supplying toner from the toner supply roller to the developing roller. A developing device, wherein the two rollers rotate in a counter direction while setting a nip width between the developing roller and the toner supply roller to 1 mm or more. 2. The image forming apparatus according to claim 1, further comprising: a powder removing unit that removes, in the developing container, exfoliated powder that has been exfoliated from a recording medium onto which the image on the photoconductor is transferred. . 3. The image forming apparatus according to claim 2, wherein the release powder is removed by a toner supply roller. 4. Applying a predetermined potential to the developing roller and the toner supply roller, and increasing the absolute value of the potential applied to the toner supply roller side from the development roller during development. Is characterized in that the absolute value of the potential applied to the toner supply roller side is lower than that of the developing roller, or the absolute value of the potential applied to the developing roller side and the absolute value of the potential applied to the toner supply roller side are equal. The image forming apparatus according to claim 1. 5. The image forming apparatus according to claim 1, wherein the toner uses toner particles manufactured by a polymerization method.