JPH0844209A - Developing device - Google Patents

Abstract

PURPOSE:To stabilize the quantity of sticking and quantity of charge of a toner on a developer carrier and to prevent the deterioration of image quality by externally sticking an abrasive to the surface part in contact with at least developer carrier of a developer supply member. CONSTITUTION:The abrasive 20 is externally stuck to the surface part of a toner supply roller 5. That is, the abrasive 20 is stuck to the surface part of the toner supply roller 5 by dipping the surface part of a foamed and molded polyurethane elastic foamed layer 52 of the toner supply roller 5 in a solvent, in which an urethane resin is dissolved and 30wt.% abrasive 20 is dispersed, and drying. As the abrasive 20, a silica fine powder having 2.5mum average volume particle diameter or an alumina fine powder having 6.7mum average volume particle diameter is used. And the abrasive 20 is externally added so that the ratio of the abrasive 20 to be added on the surface part of the toner supply roller 5 or the like to the weight of the polyurethane sponge or the like is about 2wt.%.

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 copying machine, a facsimile and a printer, and more specifically, to a developer carrying member in a developing device using a one-component developer. The present invention relates to stabilization of the toner adhesion amount and the toner charge amount.

[0002]

2. Description of the Related Art In an image forming apparatus in which an electrostatic latent image is formed on an image carrier and visualized by a developer, a one-component system is used from the viewpoints of downsizing of the developing apparatus, cost reduction, high reliability and the like. A developing device using a developer is advantageous. Particularly for colorization, it is advantageous to use a non-magnetic one-component developer because of its high transparency. A developing device using a one-component developer stores a one-component developer on its surface and conveys it along a predetermined circulation path including a developing region, and stores the one-component developer. It is known to have a storage means and a developer supply means which is in contact with the developer carrier and supplies the one-component developer stored in the developer storage means to the developer carrier. (For example, JP-A-60
(See JP-A-229057 and JP-A-61-42672).

Here, the optimum toner adhesion amount and toner charge amount on the developer carrier in a developing system using a non-magnetic one-component developer (hereinafter referred to as toner) will be described. The toner adhesion amount on the developer carrying member is about 0.6 to 1.0 mg / cm ² on the image carrying member,
It is desirable that a toner adhesion amount of about 0.5 to 0.7 mg / cm ² can be obtained on the transfer paper. The toner adhesion amount on the image carrier and the transfer paper depends not only on the toner adhesion amount on the developer carrier but also on the relative speed between the image carrier and the developer carrier in the developing area.

However, according to the developing device of this type which has been practically used in the past, since the toner layer on the developer carrying member is as small as one layer, the amount of charge of the toner conveyed to the developing area is average. The charge amount is about 5 to 15 μc / g, but the toner adhesion amount on the developer carrying member is 0.2 to 0.5 mg / cm ² , and the desired toner adhesion on the image carrying member or the like. In order to obtain the amount, it is necessary to set the speed of the developer carrier to 2 to 4 times the speed of the image carrier. As described above, when the rotation of the developer carrier is set high in order to cover the insufficient toner adhesion amount on the developer carrier, not only it is difficult to increase the image forming speed, but also the solid portion is removed. There is also a phenomenon of "from the toner trailing edge" in which the density of the trailing edge of the image becomes high when developed. This phenomenon is not a big problem in a black and white image, but in a color image there is a problem that the color is transmitted through the toner and the color is visualized, so that the density is high at the trailing edge, and especially in the case of a superimposed image, there is a color difference. .

In order to obtain a desired toner adhesion amount on the image carrier without causing such a phenomenon "from the rear end of the toner", the speed of the developer carrier is set to that of the image carrier. It is necessary to approach the speed, that is, to approach the constant-velocity development, and increase the toner adhesion amount on the developer carrying member as compared with the conventional one. Specifically, in order to secure a sufficient toner adhesion amount on the image bearing member or the transfer paper by almost constant speed development, the toner adhesion amount on the developer bearing member is
At least 0.8 mg / cm ² by contact development method with good development efficiency,
At least 1.0 mg / cm ^{2 by} non-contact development method with poor development efficiency
Need to be In order to obtain such a toner adhesion amount on the developer carrying member, the toner layer thickness must be two or more layers.

Moreover, if the toner layer on the developer carrying member conveyed to the developing area contains uncharged toner or reversely charged toner, it may cause deterioration of development transfer, background stain, resolution deterioration and the like. Therefore, the toner charge amount is 5 to 1 as an average charge amount.
0 μc / g is desirable. Further, it is desirable that the toner charge amount distribution is a stable distribution in which there are few relatively low-charged toners that cause sharpness and deterioration of resolution and scumming.

As described above, a multi-layered toner layer of two or more layers having an average charge amount of 5 to 10 μc / g with a stable charge distribution is contained on the developer carrier without containing the uncharged toner or the oppositely charged toner. If it is formed on the body, the image forming speed can be increased and constant speed development for preventing "from the trailing edge of the toner" is possible.

Therefore, as a means for attaching a desired amount of toner having a stable charge amount onto the developer carrying member, for example,
As the developer carrying member, a developer carrying member is used which is composed of a dielectric portion whose surface is regularly or irregularly distributed in a minute area and a conductive portion which is grounded. At the contact part with the rotating developer supply member,
The one-component developer is triboelectrically charged, and the dielectric part is triboelectrically charged by the developer supply member and the one-component developer to form a large number of minute electric fields in the vicinity of the developer surface. There is proposed a developing device (Japanese Patent Application No. 2-15110) in which the above-described one-component developer is carried in multiple layers on the developer carrier by the minute electric field. According to the developing device of the invention of the prior application, it becomes possible to form a multi-layer toner layer having a stable charge amount on the developer carrying member.

[0009]

However, when a developer carrying member having a strong toner conveying force is used so that the desired toner adhesion amount can be obtained as in the structure of the above-mentioned Japanese Patent Application No. 2-15110. In some cases, since the adhesion between the toner and the developer carrying member becomes strong, the toner may remain as undeveloped toner on the developer carrying member without being used for development. After that, new toner is supplied onto the developer carrying member, but the undeveloped toner adheres to the lowermost layer,
It is constrained by electrostatic attraction and cannot be separated from the developer carrier. By repeating this process, the ratio of the undeveloped toner to the total toner in the toner layer on the developer carrying member increases. The undeveloped toner thus deposited on the developer carrying member stays on the developer carrying member and is eventually fixed, while being repeatedly rubbed by the developer regulating member or the like. I will end up. As the amount of staying and adhering toner increases, the developer carrier loses its function, and it becomes impossible to obtain the toner adhesion amount and toner charge amount required for the above-mentioned constant speed development, and toner adhesion unevenness and the like occur. However, there is a problem that the image quality is adversely affected.

The present invention has been made in view of the above problems. An object of the present invention is to prevent retention and sticking of a developer on a developer carrier in a developing device using a one-component developer. By preventing it, the toner adhesion amount and the toner charge amount on the developer carrying member are stabilized, and the deterioration of the image quality is prevented.

[0011]

In order to achieve the above-mentioned object, the invention of claim 1 has a developer carrier for carrying a developer on the surface and transporting the developer on an image carrier, and the developer carrier. A developer supply member which is provided so as to contact the body and supplies the developer onto the developer carrier, and the image carrier using the developer conveyed by the developer carrier. In a developing device for visualizing the above latent image, an abrasive is externally attached to at least a surface portion of the developer supply member which is in contact with the developer carrying member. .

According to a second aspect of the present invention, there is provided a developer carrying member carrying a developer on its surface and conveying the developer on the image carrying member, and a developer carrying member provided in contact with the developer carrying member. And a developer regulating member that regulates the developer, wherein the latent image on the image carrier is visualized by using the developer conveyed by the developer carrier. It is characterized in that an abrasive is externally attached to at least a surface portion of the developer regulating member which is in contact with the developer carrying member.

According to a third aspect of the present invention, there is provided a developer carrying member carrying a developer on its surface and transporting the developer onto the image carrying member, and the developer carrying member provided so as to come into contact with the developer carrying member. In a developing device having a developer carrying member initializing member for initializing the surface of a body, and visualizing a latent image on the image carrying member by using the developer carried by the developer carrying member. An abrasive is externally attached to at least a surface portion of the developer carrying member initializing member which is in contact with the developer carrying member.

In particular, the invention of claim 4 relates to claims 1 to 3.
In the developing device, the hardness of the abrasive is larger than the hardness of the developer and smaller than the hardness of the surface of the developer carrier, and the particle diameter of the abrasive is smaller than the particle diameter of the developer. To do. As such a developer, silica or alumina can be used, for example.

[0015]

In the developing device according to any one of claims 1 to 3, an abrasive is provided on at least a surface portion of the developer supplying member, the developer regulating member, or the developer carrying member initializing member which is in contact with the developer carrying member. Is attached by external addition. And
When the surface of the member moves relative to the surface of the developer carrying member while contacting, the abrasive adhered to the surface of the member scrapes off the developer accumulated and fixed on the developer carrying member. Remove. As a result, the surface of the developer carrying member is always kept in the initial state.

Particularly, in the developing device according to the fourth aspect, since the hardness of the abrasive is larger than the hardness of the developer, the developer in which the abrasive stays and adheres on the developer carrier can be easily formed. It comes to scrape and remove. Further, since the hardness of the abrasive is smaller than the hardness of the surface of the developer carrying member, the surface of the developer carrying member is not damaged by the abrasive and is not damaged. Further, since the particle diameter of the abrasive is smaller than the particle diameter of the developer, when the abrasive is externally added to the surface portion of the developer regulating member, the developer layer on the developer carrier is No streaky unevenness occurs.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to a developing device of an electrophotographic copying machine will be described below. FIG. 2 is a front view showing a schematic configuration of the developing device according to this embodiment. The photosensitive drum 1 as an image bearing member has, for example, a peripheral speed of 120 mm / sec.
Then, it is rotationally driven in the clockwise direction of the arrow. The photosensitive drum 1
The developing device 2 is disposed on the right side of the. Around the photosensitive drum 1, a known charging device, an exposure optical system, a transfer separation device, a cleaning device, and a destaticizing device (none of which are shown) are arranged to carry out an electrophotographic process. The developing device 2 of this embodiment includes a casing 3 having an opening facing the surface of the photosensitive drum 1, and a developer which is partially exposed from the opening and is rotationally driven in a counterclockwise direction at an arrow at a predetermined peripheral speed. The developing roller 4 as a carrier, the toner supplying roller 5 as a developer supplying member that is rotationally driven in the clockwise direction of the arrow in a state of being pressed against the right side portion of the developing roller 4, and the right side portion inside the casing 3. An agitator 6 for supplying a non-magnetic one-component developer (hereinafter referred to as toner) 7 housed in a hopper portion, which is configured as a developer storage means, to the surface of the supply roller 5 and stirring the toner in the hopper portion. , A layer thickness leveling plate 8 as a developer regulating member for leveling the thickness of the toner layer on the developing roller 4 which is conveyed to the developing area A which is the portion facing the photosensitive drum 1 by the rotation of the developing roller 4. Have There.

As shown in FIG. 2, the developing roller 4 may be arranged to face the surface of the photosensitive drum 1 in the developing area A with a predetermined gap therebetween so as to perform non-contact developing. Contact development may be performed by disposing the upper toner layer so as to contact the surface of the photoreceptor 1. In any case, in order to prevent the above-mentioned phenomenon that the toner is shifted toward the trailing edge toner, the developing roller 4 is rotated such that the surface moving direction in the developing area is the same direction as the photosensitive drum 1 and the peripheral speed thereof is the same. The peripheral speed of the photosensitive drum 1 is approximately equal to the peripheral speed, that is, about 120 mm / sec in this example. However, in the contact development, if the development is completely constant speed, there is no difference in speed between the surface of the photosensitive drum 1 and the surface of the developing roller 4, so that the physical development is performed regardless of the potential of the surface of the photosensitive drum 1. Toner may adhere. To prevent this,
The peripheral speed of the developing roller 4 is set to be slightly higher. For example, the peripheral speed ratio (photosensitive drum 1 peripheral speed: developing roller 4
The peripheral speed is preferably 1: 1.05 to 1.1. With such a peripheral speed ratio, the above-mentioned trailing edge toner deviation is not noticeable.
An appropriate developing bias voltage, for example, direct current, alternating current, alternating current of direct current superimposition, pulse voltage, etc., is applied to the developing roller 4 and the layer-thickness leveling plate 8 by the bias power source 21. Particularly in the case of non-contact development, it is desirable to apply a voltage having an alternating component with good flight conditions (AC, AC with superimposed DC, or pulse voltage).

The developing roller 4 of this embodiment has a structure shown in FIG.
As shown in (b), a developing roller 4 is used in which a dielectric portion 41 capable of holding electric charges on the surface and a grounded conductor portion 42 are exposed in a mixed manner in a small area. FIG.
3B is a plan view of the surface of the developing roller 4, and FIG.
It is sectional drawing when it cut | disconnects by the aa cutting line of (a).
The size of the dielectric portion 41 is, for example, 50 to 200 in diameter.
Set to about μm. It is arranged that the dielectric parts 41 are dispersed randomly or according to a certain rule. As the area ratio of both parts, it is preferable that the area of the dielectric part 41 is in the range of 40 to 70% of the whole. As the material of the dielectric portion 41, a material having a resistance value such that electric charges are not accumulated by frictional charging by the toner supply roller 5 is used. In order to form the surface layer portion as shown in the figure, for example, the surface of a cored bar roller is knurled to form a predetermined groove, then an insulating resin is coated, and then the surface is cut to form a cored bar. The resin can be formed by exposing the resin in the groove as the dielectric portion 41 on the surface. The surface structure shown in FIGS. 4A and 4B may be replaced with the surface structure shown in FIGS. 3A to 3C. FIG. 4A is an explanatory diagram showing the surface of the developing roller, and FIG. 4B is an explanatory diagram showing the toner layer formation state on the surface.
In the surface portion of this example, after a surface layer made of a conductive material in which dielectric particles having a particle size of, for example, 50 to 100 μm are dispersed is formed on a cored bar roller, the surface layer is slightly cut if necessary. Can be formed by

The toner supply roller 5 is provided with an elastic foam layer 52 on a cored bar 51, and this elastic foam layer 52 is provided.
A large number of holes are opened on the surface so that the toner can be retained at least in the vicinity of the surface. The material of the elastic foam layer 52 of the toner supply roller 5 is toner 7 in the triboelectrification series so that it can be brought into contact with the developing roller 4 to give desired triboelectrification to the toner and the developing roller 4.
It is desirable to use a material that is intermediate between the material described above and the material of the surface portion of the developing roller 4. The toner supply roller 5 is supported, for example, at a position where it comes into contact with the surface of the developing roller 4 by a predetermined amount and comes into pressure contact, and in the forward direction in which the surface moves in the same direction as the surface of the developing roller 4 at the contact portion with the developing roller 4. Driven to rotate. The peripheral speed is preferably set to about 0.6 to 2.0 times the peripheral speed of the developing roller 4, for example.

Further, the core metal 51 of the toner supply roller 5 is supplied with the same voltage as that applied to the developing roller 4 by the bias power source 22 or the toner frictionally charged to a predetermined polarity from the toner supply roller 5 side. A voltage that forms an electric field that receives an electrostatic force toward the developing roller 4 side with the developing roller 4 may be applied.

The agitator 6 supplies the toner 7 contained in the hopper portion to the surface of the toner supply roller 5 and agitates the toner 7. However, the agitator 6 depends on the shape of the hopper and the fluidity of the toner to make the toner self-weight. If the toner can be supplied to the surface of the toner supply roller 5,
You may omit it.

The layer-thickness leveling plate 8 has a light contact pressure of about 10 to 20 g / cm for non-contact development and a contact pressure of about 30 g / cm for contact development. It is arranged so as to abut on 4. In the case of contact development, the contact pressure is set to be relatively high because in the case of contact development, the development transfer rate to the photosensitive drum 1 side is relatively high.
The appropriate toner adhesion amount above is, for example, 0.8 to 1.0 mg /
This is because it is relatively small at about cm ² . As the material of the layer-thickness leveling plate 8, as in the case of the surface material of the toner supply roller 5, the toner material on the charge series and the dielectric 4 are used.
It is desirable to adopt one located between one material. (Hereinafter, margin)

Further, as shown in FIG. 5, in order to prevent a negative afterimage and a positive afterimage, initialization as a developer carrying member initializing member is performed on the upstream side of the toner supply roller 5 in the rotation direction of the developing roller 4. The roller 11 may be provided. A bias voltage may be applied to the initialization roller 11 by the bias power supply 23 to generate an electric field that moves the residual toner on the developing roller 4 to the initialization roller 11 side.

A more specific aspect of this embodiment will be described below as a specific example. (1) Developing roller 4 A U-shaped groove having a depth of 0.1 mm and a groove width of 0.3 mm was formed in an iris shape with a pitch of 0.3 mm on the surface of a metal core roller having a diameter of 25 mm by knurling. The surface of this cored bar roller is coated with an epoxy-modified silicone resin (Toray SR2115: trademark), and 10
The dielectric layer was coated by drying at 0 ° C for about 30 minutes. The surface of this roller was cut to expose the cored bar portion as a conductor portion 42 on the surface, and the resin portion filled and left in the knurled groove was used as the dielectric portion 41. At this time, the total area of the conductor portion 42 is set to 50% of the whole (therefore, the total area of the dielectric portion 41 is set to 50% of the whole).
The surface roughness is R3 to 20 μm, preferably about 5 to 10 μm. (2) Toner supply roller 5 ・ Resistance of about 1 × 10 ⁶ Ωc on the cored bar roller 51 with a diameter of 6 mm
A sponge roller having a diameter of 14 mm having a conductive elastic foam layer 52 of m was arranged, and the sponge roller was placed in contact with the developing roller 4 with a biting amount of 1 mm. Carbon 10 is used as the conductive elastic foam layer 52.
A foamed polyurethane was used in which wt% was internally added and dispersed, and then foamed and molded. The pore opening diameter on the surface of this sponge roller was 0.2 to 0.3 mm on average. (3) Layer thickness leveling plate 8 ・ Thickness 2 mm, rubber hardness 73 degrees, and Young's modulus 0.66 g / m
The elastic plate of m ² is attached to the developing roller 4 at an edge angle of 9
The contact was placed at 0 degree and a contact pressure of 10 to 20 g / cm. As this elastic plate, 10 wt% of carbon was internally added and dispersed, and then molded urethane rubber was used. (4) Initialization roller 11 ・ Consists of a sponge roller having a diameter of 5 mm and a conductive elastic foam layer having a resistivity of about 1 × 10 ⁶ Ωcm on a core metal roller having a diameter of 10 mm. It was placed in contact with the roller 4. -For this conductive elastic foam layer, carbon 10 wt%
Was internally added and dispersed, and then foamed and molded polyurethane foam was used. (5) Development bias 21, development gap-DC-500V on the development roller 4 and the layer thickness leveling plate 8
An AC bias of 1000 Vp-p and 1000 HZ with a peak-to-peak voltage superimposed was applied (alternatively, a DC bias of -800 V may be applied).・ Development gap was set to 150 μm. (6) Toner supply roller bias 22-A bias voltage of the sponge roller core metal 14 having the same polarity as the DC component of the developing bias and an absolute value larger by 100V, for example, when the DC component of the developing bias is -500V,-
A DC bias of 600 V was applied. (7) Initializing roller bias 23-A bias having the same polarity as the DC component of the developing bias and an absolute value smaller by 100V, for example, -400V when the DC component of the developing bias is -500V.
DC bias was applied. (8) Photoreceptor 1-OPC-Negative latent images were uniformly charged so that the ground latent area was -850V and the writing area (image area) was -150V. (9) Toner 7: A negatively charged toner using a non-magnetic styrene acrylic resin and a polyester resin was used. -0.5 wt% of silica fine powder was added as an external additive.

In the above structure, the toner supply roller 5
The toner contained in the hopper is supplied to the surface by the agitator 6. The toner supplied to the toner supply roller 5 is carried on the surface of the elastic foam layer 52 or in the pores,
When the toner supply roller 5 rotates clockwise, the toner supply roller 5 is conveyed toward the contact portion B between the toner supply roller 5 and the developing roller 4.

The friction between the developing roller 4, the toner 7 and the toner supplying roller 5 causes the dielectric portion 4 of the developing roller 4 to move.
1. A charge having a polarity opposite to the desired toner charge polarity (charge having the same polarity as the photoconductor charge in normal development (P / P), and charge having a polarity opposite to the photoconductor charge in reverse development (N / P)) 3) is applied to the electric field line E, for example, as shown in FIG.
As shown by, a microfield (closed electric field) is created on the developing roller 4. On the other hand, since the toner supply roller 5 is rotating in the forward direction with respect to the developing roller 4, the toner 7 carried on the toner supply roller 5 is slid between the developing roller 4 and the toner supply roller 5, and most of them are desired. (In normal development, the polarity is opposite to that of the photoconductor, and in reversal development, it is the same as that of the photoconductor).

Then, the charged toner 7 on the toner supply roller 5 is electrostatically attracted by the electric field of the micro field on the developing roller 4, and adheres to the surface of the developing roller 4 in multiple layers. As a result, the developing roller 4 exits the contact portion B in a state where the sufficiently charged toner is carried in multiple layers. In this embodiment, since the toner supply roller 5 and the developing roller 4 are rotated in the forward direction, the toner 7 on the toner supply roller 5 is the developing roller 4 and the toner supply roller 5.
Almost all of them are charged by being inspected between. Further, due to the rotation of the toner supply roller 5, the uncharged or weakly charged toner 7 from the hopper is not supplied onto the developing roller 4 that has passed through the contact portion B.

The toner layer on the developing roller 4 that has passed through the contact portion B is rubbed to a uniform thickness by the layer-thickness leveling plate 8 that is in light contact with the developing roller 4 to form a uniform thin layer. ,
When the developing roller 4 rotates, it is conveyed to the developing area A. At this time, the toner adhesion amount on the developing roller 4 is 1.5 to 2.0.
A toner layer of mg / cm ² and a toner charge amount of 15 μC / g is formed. Then, in the developing area A, the development is performed while the surface of the developing roller 4 to which the optimum developing bias is applied by the contact or non-contact developing method and the surface of the photosensitive drum 1 move at a substantially constant speed.

The residual toner in the non-image portion remaining on the surface of the developing roller 4 without adhering to the surface of the photosensitive drum 1 when passing through the developing area A is the toner supply roller 5 and the initialization roller 1.
1, the charge on the developing roller 4 is mechanically and electrically scraped, and the electric charge on the developing roller 4 is also made constant by the frictional charging by the toner supply roller 5, whereby the surface of the developing roller 4 is initialized.

By the way, when the running test was conducted under the above-mentioned configuration and conditions, the toner 7 started to adhere to the developing roller 4 after about 3,000 copies, and the image abnormality (solid portion) occurred after about 5,000 copies. Density unevenness) was observed, and the image density was reduced. This phenomenon was the same even in the case of the configuration provided with the initialization roller 11 as shown in FIG.

Therefore, in this embodiment, as shown in FIGS. 1, 6 and 7, at least one surface portion of the toner supply roller 5, the layer thickness leveling plate 8 and the initialization roller 11 is used. The abrasive 20 is externally attached thereto. In FIG. 1, an abrasive 20 is provided on the surface of the toner supply roller 5.
Is attached by external addition. The surface of the elastic foam layer 52 made of polyurethane foamed and molded of the toner supply roller 5 is dissolved in urethane resin to disperse the abrasive 20 in an amount of 30 wt%. After immersing in a solvent such as toluene and drying at 100 ° C for 30 minutes,
The abrasive 20 is attached to the surface of the toner supply roller 5. FIG. 6 shows that the abrasive 20 is applied to the surface of the initialization roller 11.
Is attached by external addition, the urethane resin is dissolved in the surface portion of the elastic foam layer of polyurethane foamed and molded of the initialization roller 11 to disperse the abrasive 20 in an amount of 30 wt%. After being immersed in a solvent such as toluene, the abrasive 20 is attached to the surface of the initialization roller 11 by drying at 100 ° C. for 30 minutes. FIG. 7 shows a structure in which the abrasive 20 is attached to the surface of the layer-thickness leveling plate 8 by external addition. Then, the abrasive 20 is immersed in a solvent such as toluene in which 30 wt% of the abrasive has been dispersed, and then dried at 100 ° C. for 30 minutes to adhere the abrasive 20 to the surface portion of the layer-thickness leveling plate 8.

As the above-mentioned abrasive 20, fine silica powder having an average volume particle diameter of 2.5 μm (Nip, manufactured by Nippon Silica Industry Co., Ltd.) is used.
sil E-200A: trademark) or average volume particle size 6.
7 μm alumina fine powder (Sumitomo Chemical Co., AKP-1
5: Trademark). Then, the polishing is performed so that the addition rate of the abrasive 20 on the surface portion of the toner supply roller 5, the initialization roller 11 or the layer-thickness leveling plate 8 is about 2 wt% with respect to the weight of polyurethane sponge or urethane rubber. Agent 20 is externally added. Further, since the silica fine powder or the alumina fine powder used as the abrasive 20 is easily dispersed in the solvent, it is easily externally added to the polyurethane sponge or urethane rubber. Further, the hardness of the abrasive 20 is larger than that of the toner 7 and smaller than that of the surface of the developing roller 4, and the particle size thereof can be smaller than the particle size of the toner 7. It has become.

As described above, according to the present embodiment, at least one surface portion of the elastic foam layer 52 of the toner supply roller 5, the elastic foam layer of the initialization roller 11, and the layer thickness leveling plate 8 is formed. The abrasive 20 is attached by external addition. Then, when the surface of the toner supply roller 5, the initialization roller 11 or the layer thickness leveling plate 8 moves relative to the developing roller 4 while making contact, the attached abrasive 20 stays on the developing roller 4. Also, the adhered toner 7 is scraped off and removed. Therefore, it is possible to prevent the toner 7 from sticking to the developing roller 4 with a simple and inexpensive structure in which the abrasive 20 is externally added, so that the surface of the developing roller 4 is always kept in the initial state, The toner adhesion amount and the toner charge amount are stable over time, and the deterioration of the image quality due to toner adhesion unevenness and the like can be prevented.

Further, in this embodiment, since the hardness of the silica fine powder or the alumina fine powder used as the abrasive 20 is larger than that of the toner 7, the toner 7 retained and fixed on the developing roller 4 by the abrasive 20 is removed. Can be easily removed like scraping. Further, since the hardness of the abrasive 20 is lower than the hardness of the surface of the developing roller 4, the surface of the developing roller 4 is not damaged by the abrasive 20 and is not damaged.

Further, in this embodiment, since the fine silica powder or fine alumina powder having a particle size smaller than that of the toner 7 is used as the abrasive 20, the abrasive 20 is externally added to the leveling plate 8, for example. Even in this case, the toner layer on the developing roller 4 does not have streaky unevenness.

Further, in this embodiment, silica fine powder or alumina fine powder is used as the abrasive 20, but since the silica fine powder and the alumina fine powder are substances that can be externally added to the toner 7, Even if the powder is slightly detached and mixed in the toner 7, the image quality is not deteriorated.

Further, the following results were obtained in the concrete copy test of this embodiment. The abrasive 20 is externally attached to one of the surface portions of the elastic foam layer 52 of the toner supply roller 5, the elastic plate of the layer-thickness leveling plate 8 or the elastic foam layer of the initialization roller 11. Then, when a running test was performed, as shown in FIG.
Toner 7 on developing roller 4 even when copying 000 sheets
No sticking was observed, and no image abnormality such as a decrease in image density occurred. Here, the data indicated by the symbol □ is for abrasive 2
0 is the measured data when the silica fine powder is externally added, and the data indicated by the symbol + is the measured data when the alumina fine powder is externally added as the abrasive 20, and the data indicated by the symbol ◇. Is the measurement data when the abrasive 20 was not added externally.

In this embodiment, the reversal developing method is used, but the normal developing method can also be applied. In the case of this regular developing system, the material of the dielectric portion 41 of the developing roller 4 is Teflon resin, polyethylene resin, the toner supply roller 5, the layer thickness leveling plate 8, and the material of the initialization roller 11 is polyurethane resin, polycarbonate. Polystyrene resin, acrylic resin or the like can be used as the material of the resin and the toner 7. Then, as an appropriate developing bias 21, for example, -200V is used.

Further, in the present embodiment, the developing device using the non-magnetic one-component developer, which is equipped with the developing roller 4 whose surface is composed of the dielectric portion 41 and the conductor portion 42 in order to increase the adhered toner. However, the present invention can be similarly applied to a developing device or the like using a magnetic one-component developer, and further, a developing roller not provided with a dielectric portion 41 and a conductor portion 42, and It can also be applied to a developing roller equipped with a magnet.

Further, in this embodiment, the toner 7 accumulated and fixed on the developing roller 4 is removed, but the present invention is also applied to the case where the deposits other than the toner 7 are accumulated and fixed on the developing roller 4. it can.

[0042]

According to the developing device of the first to fourth aspects, at least a surface portion of the developer supply member, the developer regulating member, or the developer carrying member initializing member that comes into contact with the developer carrying member. Abrasive is externally attached to. Then, when the surface of the member moves relative to the surface of the developer carrier while contacting, the abrasive adhering to the surface portion of the member stays and adheres on the developer carrier. Remove the developer like scraping. As a result, the surface of the developer carrying member is always kept in the initial state. Therefore, there is an effect that the adhered amount and the electrified amount of the developer on the developer carrying member are stable over time, and the deterioration of image quality due to uneven adhesion of the developer can be prevented. Further, there is an effect that the retention and sticking of the developer on the surface of the developer carrying member can be prevented by a simple and inexpensive structure in which the abrasive is externally added to at least the surface portion of the member.

Particularly, according to the developing device of the fourth aspect, since the abrasive has a hardness higher than that of the developer, the developer retained and fixed on the developer carrier by the abrasive is easily scraped off. The effect is that it can be removed.
Further, since the hardness of the abrasive is smaller than the hardness of the surface of the developer carrying member, there is an effect that the surface of the developer carrying member is not damaged and damaged by the abrasive. Further, since the particle size of the abrasive is smaller than the particle size of the developer, even when the abrasive is externally added to the surface of the developer regulating member, the developer layer on the developer carrier is This has the effect of preventing streaky unevenness.

[Brief description of drawings]

FIG. 1A is a schematic configuration diagram of a developing roller 4 and a toner supply roller 5 pressed against the developing roller 4 according to the present embodiment, and FIG.
Is an enlarged view of the same pressure contact part.

FIG. 2 is a schematic configuration diagram of a developing device according to an embodiment.

3A is a plan view showing a part of the surface of a developing roller 4 of the developing device, FIG. 3B is a sectional view of the surface portion, and FIG. 3C is a description of a toner layer formation state on the surface. Fig.

FIG. 4A is a plan view showing a part of the surface of a developing roller 4 according to a modified example, and FIG. 4B is an explanatory view of a toner layer forming state on the surface.

FIG. 5 is a schematic configuration diagram of a developing device according to a modification.

FIG. 6A is a schematic configuration diagram of a developing roller 4 and an initialization roller 11 pressed against the developing roller 4 according to the present embodiment, and FIG. 6B is an enlarged view of the pressure contact portion.

7A is a schematic configuration diagram of a developing roller 4 and a layer-thickness leveling plate 8 in contact with the developing roller 4 according to the present embodiment, and FIG. 7B is an enlarged view of the contact portion.

FIG. 8 is a characteristic diagram showing the relationship between the number of copies and image density.

[Explanation of symbols]

 1 Photosensitive Drum 2 Developing Device 3 Casing 4 Developing Roller 5 Toner Supply Roller 6 Agitator 7 Toner 8 Layer Leveling Plate 11 Initializing Roller 20 Abrasive 41 Dielectric Part 42 Conductor Part 51 Core Bar 52 Elastic Foam Layer

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display location G03G 15/08 504 B 9/08

Claims (4)

[Claims] 1. A developer carrying member which carries a developer on a surface thereof and conveys it onto an image carrying member, and a developer carrying member which is provided so as to come into contact with the developer carrying member. And a developer supplying member for supplying the developer, wherein the developer conveyed by the developer carrying member is used to visualize the latent image on the image carrying member. A developing device, wherein an abrasive is externally attached to at least a surface portion that comes into contact with the developer carrying member. 2. A developer carrying member carrying a developer on its surface and conveying it onto an image carrying member, and a developer provided on the developer carrying member so as to come into contact with the developer carrying member. A developer regulating member for regulating, wherein the developer conveyed by the developer carrying member is used to visualize a latent image on the image bearing member, A developing device, wherein an abrasive is externally attached to at least a surface portion that comes into contact with the developer carrying member. 3. A developer carrying member carrying a developer on its surface and feeding it onto an image carrying member, and a developer carrying member provided in contact with the developer carrying member to initialize the surface of the developer carrying member. In a developing device having a developer carrying member initializing member, the developer carried by the developer carrying member is used to visualize a latent image on the image carrying member. A developing device, wherein an abrasive is externally attached to at least a surface portion of the activating member which is in contact with the developer carrying member. 4. The hardness of the abrasive is greater than the hardness of the developer and less than the surface hardness of the developer carrier,
4. The developing device according to claim 1, wherein the particle size of the abrasive is smaller than the particle size of the developer.