JPH07199641A - Developing device - Google Patents

Abstract

PURPOSE:To prevent developer from staying on/sticking to a developer carrier, to stabilize an amount of toner sticking to the developing carrier and an amount of toner electrification and to prevent deterioration in image quality by adding silica into the surface of a member which slides on the developer carrier. CONSTITUTION:Electrified toner on a toner supply roller 5 is electrostatically attracted by the electric field of a microfield on a developing roller 4, and sticks to the surface of the developing roller 4 in the form of a multilayer. The toner layer on the developing roller 4 which has passed a contact part is made into a uniform thin layer by being uniformly rubbed by a layer- thickness-regulating plate, which slightly abuts on the developing roller 4, so as to have a uniform thickness, and is carried to a developing area by the rotation of the developing roller 4. Silica fine powder 20 is added into at least the toner supply roller 5 or layer-thickness-regulating plate. It is preferable that the added silica fine powder 20 have a volume averaged grain size of 0.5mum or larger. Thus, the toner staying on and sticking to the surface of the developing roller 4 can be scraped off.

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 a latent image carrier and visualized by a developer, one component is used in view of downsizing of the developing apparatus, cost reduction, high reliability and the like. A developing device using a system 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-6
0-229057, 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 amount of toner deposited on the developer carrying member, the latent image bearing member at 0.6~1.0mg / cm ² about the toner adhesion amount, 0.5~0.7mg / cm ² of about toner adhesion on paper transfer It is desirable that the amount be obtained. The toner adhesion amount on the latent 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 latent 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 carrier is 0.2 to 0.5 mg / cm ² , and the desired toner on the latent image carrier is In order to obtain the adhesion amount, it is necessary to set the speed of the developer carrier to 2 to 4 times the speed of the latent 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 latent image bearing member without causing such a phenomenon "from the rear end of the toner", the speed of the developer bearing member is set to the latent image bearing member. It is necessary to approach the speed of the body, that is, to approach the constant-velocity development, and increase the toner adhesion amount on the developer carrying member as compared with the conventional case. Specifically, in order to secure a sufficient amount of toner adhered on the latent image carrier or transfer paper at substantially constant speed development, the amount of toner adhered on the developer carrier is determined by a contact development method with good development efficiency. At least 0.8 mg
/ cm ² , at least 1.0 by non-contact development method with poor development efficiency
Must be mg / cm ² . 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 object, the present invention uses a developer carried by a developer carrying body carrying a developer on the surface and carrying it on an image carrying body. In a developing device that visualizes a latent image on the image bearing member, silica having a volume average particle diameter of 0.5 μm or more is internally added to the surface portion of a member that contacts the developer bearing member. It is a feature.

Here, as the member which comes into contact with the developer carrying member, there is provided a developer having a developer supplying member which is provided so as to come into contact with the developer carrying member and supplies the developer onto the developer carrying member. The developer supply member can be used in the apparatus. The developer regulating member can be used in a developing device that is provided so as to contact the developer carrying member and has a developer regulating member that regulates the developer on the developer carrying body. Further, in a developing device having a developer carrying member initializing member which is provided so as to contact the developer carrying member and initializes the surface of the developer carrying member, the developer carrying member initializing member can be used. .

As the silica, it is desirable to use one having a hardness higher than that of the developer. Further, it is desirable to use acicular or amorphous silica. Further, it is desirable to use silica having hydrophobicity.

When the member contacting the developer carrying member is made of urethane sponge, the weight ratio of silica to be internally added to the weight of urethane sponge should be 0.5% by weight or more. desirable.

Further, when the member to which silica is internally added is a foam, it is desirable to use silica having a volume average particle size of 0.5 μm or less so that the foam can be satisfactorily expanded.

The present invention particularly provides a developing device using a developer carrier for forming a large number of minute closed electric fields near the surface and carrying the developer on the surface by the minute closed electric fields.
It is valid.

[0017]

In the present invention, the developer-carrying member is internally added to the member which comes into contact with the developer-carrying member, and the polishing action of silica partially exposed on the surface in contact with the developer-carrying member is carried out. The developer stayed and fixed on the top is scraped off and removed. As a result, the surface of the developer carrying member is always kept in the initial state.

[0018]

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 so as to face the surface of the photosensitive drum 1 with a predetermined gap in the developing area A so as to perform non-contact development. 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 the present 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. Figure 3
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 core metal 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 elastic foam layer 52 will be described in detail later. Further, instead of the elastic foam layer 52, a brush layer in which the tips of a large number of fibrous members are in contact with the surface of the developing roller 4 may be used. A synthetic fiber or the like can be used for the fibrous member. The material of the elastic foam layer 52 and the brush layer of the toner supply roller 5 is toner in the triboelectrification series so that the toner and the development roller 4 can be contacted with the development roller 4 and desired triboelectrification can be given. It is desirable to use a material that is intermediate between the material of No. 7 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, for example, about 0.6 to the peripheral speed of the developing roller 4.
It is desirable to set it to 2.0 times. 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 toner frictionally charged to a predetermined polarity from the toner supply roller 5 side to the developing roller 4 side. A voltage that forms an electric field that receives an electrostatic force directed toward the side between the developing roller 4 and 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.

Further, in order to prevent a negative afterimage and a positive afterimage, an initialization roller as a developer carrying member initialization member is provided upstream of the toner supply roller 5 in the rotation direction of the developing roller 4. Good. (Hereafter, margin)

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 0.2 mm was formed in an iris shape with a pitch of 0.3 mm on the surface of a core metal 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. This conductive elastic foam layer 52
As the material, 10% by weight of carbon was internally added and dispersed, and then foamed and molded polyurethane foam was used. The pore opening diameter on the surface of this sponge roller was 0.2 to 0.3 mm on average. Instead of the sponge roller, a brush roller having a conductive brush layer having a resistivity of about 1 × 10 ⁶ Ωcm on a core metal roller 51 having a diameter of 6 mm is used, and the brush roller is applied to the developing roller 4 with a biting amount of 1 mm. They may be placed in contact with each other. The fibrous member used for this conductive brush layer is carbon 10 wt.
It is possible to use polyester fibers in which% is internally added and dispersed. (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) Development bias 21, development gap-DC-500V on the development roller 4 and the layer thickness leveling plate 8.
Peak-to-peak voltage 1000Vp-p
An AC bias of 1000 HZ was applied (instead of this, −
A DC bias of 800 V may be applied).・ Development gap was set to 150 μm. (5) Toner supply roller bias 22-A bias voltage having the same polarity as the direct current component of the developing bias and an absolute value larger by 100V, for example, when the direct current component of the developing bias is -500V,-
A DC bias of 600 V was applied. (6) Photoreceptor 1-OPC-Negative latent image was uniformly charged so that the background part was -850V and the writing part (image part) was -150V. (7) 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 toner 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 mechanically and electrically scraped off by the toner supply roller 5. Further, 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 is carried out under the above-mentioned configuration and conditions, the toner 7 on the developing roller 4 is made by copying about 3,000 sheets, as indicated by the symbol b in FIGS. 6 (a) and 6 (b). The ID (image density) starts to decrease due to sticking, and the image density decreases to such an extent that image abnormalities (solid image density unevenness) are observed in about 5,000 or more copies. This phenomenon was the same even in the case of the configuration provided with the above-mentioned initialization roller.

Therefore, in the apparatus of this embodiment, silica fine powder 20 is internally added to at least one of the toner supply roller 5 and the layer thickness leveling plate 8. Specifically, regarding the toner supply roller 5, silica fine powder 20 having a volume average particle diameter of 3 μm is included in polyurethane, which is a material of the elastic foam layer 52 of the toner supply roller 5, together with the carbon.
(Specifically, Nipsil E-20 manufactured by Nippon Silica Industry Co., Ltd.
2 wt% of 0A) is internally added and dispersed, and then foamed and molded. FIG. 1B is an enlarged schematic view showing a contact portion between the toner supply roller 5 and the developing roller 4 indicated by a broken line circle in FIG. Is partially exposed on the surface in contact with the developing roller 4. When a brush layer is used instead of the elastic foam layer 52, silica fine powder 20 is internally added and dispersed together with the carbon in the polyester, which is the material of the fibrous member of the brush layer, to form polyester fiber. Mold.

As for the layer-thickness leveling plate 8, silica fine powder 20 having a volume average particle size of 3 μm (specifically, Nippon Silica) is incorporated in the urethane rubber which is the material of the layer-thickness leveling plate 8 together with the above carbon. Industrial Nipsil E-200
2% by weight of A) is internally added and dispersed, and thereafter, it is molded. FIG. 5B is an enlarged schematic view showing a contact portion between the layer-thickness leveling plate 8 and the developing roller 4 indicated by a circle formed by a broken line in FIG. 5A. Part of the powder 20 is partly exposed on the surface in contact with the developing roller 4.

As described above, silica 20 is provided on at least one of the toner supply roller 5 and the layer thickness leveling plate 8.
Is added internally, the symbol a in FIGS. 6 (a) and 6 (b)
As shown in, it was possible to perform good copying without lowering the image density up to 30,000 copies.

When the particle size of silica to be internally added and the appropriate range of the internally added amount were examined, a good result was obtained with a volume average particle size of 0.5 μm or more. It was also found that the internal addition amount is preferably 0.5 wt% or more. That is, for the same particle size, FIG.
As shown in (a), the toner having a volume average particle diameter of 0.5 μm or more did not cause toner sticking on the developing roller 4 even after copying 30,000 sheets. In the figure (a), the symbol ◯ indicates that toner is not fixed, and the symbol x indicates that toner is fixed. When the particle size was 0.1 to 0.3 μm, toner adhered to the developing roller 4 before the copying of 20,000 sheets. If the particle size exceeds 5 μm, the toner supply roller 5
It was also found that polyurethane, which is the material of the elastic foam layer 52, is difficult to fire. Further, regarding the internally added amount, the same particle diameter of the toner supply roller 5 to the elastic foam layer 52 is 3 μm.
As shown in FIG. 7B, which shows the result of changing the internal addition amount of silica, the toner fixation on the developing roller 4 by the copying of 250,000 sheets is achieved when the internal addition amount is 0 (no addition) to 0.3 wt%. Occurs, and 3000 is added when the internal content is 0.5 wt% or more.
The toner fixation on the developing roller 4 did not occur until the 0th copy. In FIG. 7B, the symbol Δ indicates that a small amount of toner adhered.

As the silica 20, it is preferable to use one having a hardness higher than that of the toner 7, a needle-like or amorphous one, and a hydrophobic one.

As described above, according to this embodiment, at least one of the members for rubbing the surface of the developing roller 4, such as the elastic foam layer 52 of the toner supply roller 5 or the brush layer and the layer thickness leveling plate 8 is used. Silica 20 having a volume average particle size of 0.5 μm or more
Since the toner is internally added, the toner 7 accumulated and fixed on the developing roller 4 can be removed by scraping it off.
Therefore, it is possible to prevent the toner 7 from sticking on the developing roller 4 with a simple and inexpensive structure in which the silica 20 is added internally.
The surface of the developing roller 4 is always kept in the initial state, the toner adhesion amount and the toner charge amount on the developing roller 4 are stable over time, and deterioration of image quality due to uneven toner adhesion or the like can be prevented.

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, for example, −200 V is used as an appropriate developing bias 21.

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.

[0041]

According to the present invention, the development is carried out by the polishing action of silica which is internally added to the member which comes into contact with the developer carrying member and whose part is exposed on the surface which comes into contact with the developer carrying member. Since the developer staying and fixed on the agent carrier is removed, the surface of the developer carrier 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 achieved with a simple and inexpensive structure in which silica is internally added to at least the surface portion of the member.

In particular, if silica having a hardness higher than that of the developer is used as the silica, the developer staying and adhering to the surface of the developer carrying member can be satisfactorily removed so as to be scraped off.

Further, when acicular or amorphous silica is used as the above-mentioned silica, it is difficult for the silica to be detached from the surface of the internally added member, and the polishing action can be exerted for a long period of time.

Further, when silica having hydrophobicity is used as the above-mentioned silica, as compared with the case where hydrophilic silica is used,
It is possible to suppress environmental fluctuations in the charging of the developer and the like.

[Brief description of drawings]

FIG. 1A is a schematic configuration diagram of a developing roller and a toner supply roller according to the present exemplary embodiment. (B) is an enlarged view of a pressure contact portion of both rollers.

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

FIG. 3A is a plan view showing a part of the surface of the developing roller of the developing device. (B) is sectional drawing of the surface part. (C) is an explanatory view of a toner layer formation state on the surface.

FIG. 4A is a plan view showing a part of the surface of a developing roller according to a modification. FIG. 6B is an explanatory diagram of a toner layer formation state on the surface.

FIG. 5A is a schematic configuration diagram of a layer-thickness leveling plate. FIG. 6B is an enlarged view of the contact portion between the equalizing plate and the developing roller.

FIG. 6A is a characteristic diagram showing the relationship between the number of copies and the image density. FIG. 6B is a characteristic diagram showing the relationship between the number of copies and the solid density uniformity rank.

FIG. 7A is a diagram showing the results of examining the relationship between the particle size of silica to be added and toner adhesion. FIG. 7B is a diagram showing the results of examining the relationship between the amount of silica added and toner adhesion.

[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 20 Silica Fine Powder 41 Dielectric Part 42 Conductor Part 51 Core Bar 52 Elastic Foam Layer

Claims (6)

[Claims] 1. A developing device which visualizes a latent image on an image carrier by using the developer carried by a developer carrier carrying a developer on the surface and carrying it on the image carrier. At
A developing device, wherein silica having a volume average particle diameter of 0.5 μm or more is internally added to a surface portion of a member which comes into contact with the developer carrying member. 2. A developer carrying member which carries a developer on a surface 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 the developer is placed on 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 silica having a volume average particle diameter of 0.5 μm or more is internally added to at least a surface portion in contact with the developer carrying member. 3. A developer carrying member carrying a developer on its surface and carrying it on an image carrying member, and a developer carrying member provided so as to come into contact with said 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 silica having a volume average particle diameter of 0.5 μm or more is internally added to at least a surface portion in contact with the developer carrying member. 4. The developing device according to claim 1, wherein the hardness of the silica is higher than the hardness of the developer. 5. The developing device according to claim 1, wherein the silica is acicular or amorphous silica. 6. The developing device according to claim 1, wherein the silica is a hydrophobic silica.