JP2000206787A - Developing device - Google Patents

Abstract

[PROBLEMS] To provide a developing device capable of reliably preventing toner leakage due to scraping of a toner seal material even when a polymerized toner is used as a non-magnetic one-component developer. SOLUTION: A polymerized toner is used as a toner 55, and a base material 58b of a developing roller 58 is formed of urethane rubber, and a surface coat layer 58c containing fluorine is provided on the base material 58b to form a chargeability of the urethane rubber. To improve
Further, a toner seal member 80 made of urethane sponge or the like is brought into close contact with the developing roller 58 via a Teflon felt 81. The external additives include those having a BET value of at least 100 or less.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention belongs to the technical field of a developing device for forming a thin layer of developer on a developer carrier by a layer thickness regulating member.

[0002]

2. Description of the Related Art Conventionally, in a developing apparatus using a non-magnetic one-component developer, a layer thickness regulating blade made of conductive or insulating rubber is brought into elastic contact with a developing roller made of conductive rubber or the like, Development is performed by forming a thin layer of a non-magnetic one-component developer on a developing roller, and transporting the thin layer of the developer to a region facing the photosensitive drum and applying it to an electrostatic latent image.

[0003] In order to perform good development by such a method, it is important that the non-magnetic one-component developer has a sufficient charge amount with a predetermined charge polarity, and various improvements have hitherto been made. I have.

[0004] In particular, in recent years, a technique using a polymerized toner produced by a polymerization method as a non-magnetic one-component developer has attracted attention. Since the polymerized toner has an almost spherical shape, it has a very high fluidity compared to the pulverized toner, performs good triboelectric charging, and is easily affected by an electric field. A good image can be formed.

[0005]

However, since the polymerized toner has good fluidity, toner leakage from a developing device is liable to occur. Further, once toner leakage occurs, compared with pulverized toner, As a result, a large amount of toner leaks, and the inside of an image forming apparatus such as a printer is significantly contaminated.

In the above-described developing device,
The toner sealing material is prevented from leaking from both ends of the developing roller by rubbing the toner sealing material on the peripheral surface of the developing roller. There is a problem that the developing roller is scraped by the polymerized toner. In particular, in a polymerized toner having low mechanical strength, it is effective to add a large external additive having a BET value of 100 or less in order to prevent the external additive from being embedded in the toner base particles. There is a problem in that the external additive acts as a polishing agent, thereby significantly shaving the developing roller.

In view of the above problems, the present invention provides a developing device capable of reliably preventing toner leakage due to scraping of a toner sealing material even when a polymerized toner is used as a non-magnetic one-component developer. The challenge is to do.

[0008]

According to a first aspect of the present invention, there is provided a developing device comprising: a layer thickness regulating member provided on a peripheral surface of a developer carrier for carrying and transporting a non-magnetic one-component developer; A developing device that presses the developer, passes the developer through the pressing portion to form a thin layer of the developer, and transports the thin layer of the developer to a developing area by the developer carrier to perform development. And a developer sealing means provided so as to be in pressure contact with the peripheral surfaces on both ends in the longitudinal direction of the developer carrier, wherein the developer is
A polymerized toner obtained by a polymerization method, wherein at least the substrate of the developer carrier is formed of conductive urethane rubber.

According to the first aspect of the present invention, the polymerized toner as the non-magnetic one-component developer is conveyed while being carried on the developer carrier, and furthermore, is fixed at a predetermined portion at a pressing portion with the layer thickness regulating member. Formed as a thin layer and subjected to development in the development area. Particularly, since the polymer toner has an extremely high fluidity, good triboelectric charging is performed and very good development is performed. Although such a high fluidity easily causes toner leakage, a developer sealing means is provided on the peripheral surface at both ends in the longitudinal direction of the developer carrying member so as to be in pressure contact with the developer carrying member. Thus, the leakage of the polymerized toner having good fluidity is surely prevented. Even if the polymerized toner slightly enters the pressure contact portion between the developer carrying member and the developer sealing means, at least the base material of the developer carrying member is a conductive material having excellent mechanical strength. Since it is formed of urethane rubber, it is difficult to be scraped off by the polymerized toner to which an external additive is added, and a gap due to the scraping is generated in a pressure contact portion with the developer sealing means. . Therefore, the toner is reliably sealed and the occurrence of toner leakage is prevented.

According to a second aspect of the present invention, in order to solve the above problem, the developing device according to the first aspect,
The developer carrier has a surface coat layer on the base material formed of the conductive urethane rubber.

According to the developing device of the present invention, the developer carrying member is constituted by providing a surface coat layer on a base material made of conductive urethane rubber. Provide the desired chargeability or surface roughness. Even if the polymerized toner slightly enters the pressure contact portion between the developer carrier and the developer sealing means, at least the base material of the developer carrier is a conductive material having excellent mechanical strength. Therefore, even if the surface coat layer is shaved by the polymerized toner to which an external additive is added, toner leakage occurs at a pressure contact portion with the developer sealing means. It does not create gaps due to the slight scraping. Therefore, the toner is reliably sealed,
Prevents toner leakage.

According to a third aspect of the present invention, there is provided a developing device according to the second aspect, wherein:
The surface coat layer of the developer carrier is a layer that has been subjected to a surface treatment that improves the chargeability of the surface of the developer carrier.

According to the third aspect of the present invention, a surface coat layer is provided on a base material made of conductive urethane rubber, which has been subjected to a surface treatment for improving the chargeability of the surface of the developer carrier. Therefore, even when urethane rubber having poor chargeability to the developer is used as the base material of the developer carrying member, the developer is satisfactorily charged by friction. Further, even if the polymerized toner slightly enters the pressure contact portion between the developer carrying member and the developer sealing means, the developer carrying member has at least a base material excellent in mechanical strength. Since it is made of conductive urethane rubber, even if the surface coat layer is shaved by the polymerized toner to which an external additive has been added, toner leakage may occur at the pressure contact portion with the developer sealing means. It does not create gaps due to the shavings that would occur.
Therefore, the toner is reliably sealed and the occurrence of toner leakage is prevented.

According to a fourth aspect of the present invention, there is provided a developing device according to the first aspect, wherein the surface coat layer of the developer carrying member is provided. Is characterized in that it is formed to have a value smaller than the average particle size of the polymerized toner.

According to a fourth aspect of the present invention, in the case where the polymerized toner slightly enters the pressure contact portion between the developer carrier and the developer sealing means and the surface coat layer is scraped. Even so, the layer thickness of the surface coat layer is formed so as to be smaller than the average particle diameter of the polymerized toner, so that toner leakage from the shaved portion of the surface coat layer is reliably prevented. I do.

According to a fifth aspect of the present invention, in order to solve the above-mentioned problem, in the developing device according to the first aspect of the present invention, the developer is large in the amount of the polymerized toner. At least two or more external additives having different sizes are added, and at least one of the external additives has a BET
It is an external additive having a value smaller than 100.

According to the developing device of the present invention, at least two or more kinds of external additives having different sizes are added to the polymerized toner, and the external additive having a small particle diameter causes the polymerized toner to flow. The properties are further improved. Further, at least one of the external additives has a BET value of 100.
Since it is a smaller external additive, that is, an external additive having a large particle diameter, the external additive having the small particle diameter is reliably prevented from being embedded in the toner base particles. Such BET value is 10
An external additive smaller than 0 can be an abrasive, but since the developer carrying member is at least a base made of conductive urethane rubber, scraping by the external additive having such a large particle size is surely prevented.

According to a sixth aspect of the present invention, in order to solve the above-mentioned problem, the developing device according to any one of the first to fifth aspects, wherein the developer sealing means includes at least the developing device. The portion that is in pressure contact with the agent carrier is formed of Teflon felt.

According to a sixth aspect of the present invention, in the developing device, the developer sealing means is provided so as to be in pressure contact with the peripheral surfaces on both ends in the longitudinal direction of the developer carrying member, and at least the developer sealing means is provided. The portion pressed against the carrier is made of Teflon felt. Since Teflon felt has a low frictional resistance to the developer carrying member, the developer sealing means is brought into contact with the developer carrying member by sufficient pressure so that toner does not enter between the developer carrying member and the developer sealing means. Even when the developer is rubbed, the rotational torque of the developer carrying member does not become too high. Also, there is no generation of high heat due to friction. When the pressure of the developer sealing means is strong, the toner enters between the developer holding body and the developer sealing means, thereby promoting scraping of the developer holding body. Since at least the base material of the body is formed of urethane rubber, even if the developer sealing means is strongly pressed, scraping of the developer carrier is reduced.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a schematic sectional side view of a laser printer as an image forming apparatus to which the present invention is applied. In FIG. 1, a laser beam printer 1 includes a feeder unit 10 for feeding a sheet P as a recording medium on the bottom of a main body case 2. The feeder unit 10 includes a paper pressing plate 11 pressed by a compression spring (not shown) and a paper feed roller 13.
3 and the uppermost sheet P is supplied at a predetermined timing.

A pair of registration rollers 14 and 1 are located downstream of the paper feed roller 13 in the transport direction indicated by arrow A.
5 is rotatably supported, and conveys the sheet P to a transfer position formed by the photosensitive drum 20 and the transfer roller 60, which will be described later, at a predetermined timing.

The photosensitive drum 20 is made of a positively chargeable material, for example, an organic photoreceptor mainly composed of positively chargeable polycarbonate. More specifically, the photosensitive drum 20 has, for example, a cylindrical aluminum sleeve as a main body, and has a predetermined thickness (for example, about 20 μm) in which a photoconductive resin is dispersed in polycarbonate on an outer peripheral portion thereof. It is composed of a hollow drum on which a conductive layer is formed, and is rotatably supported by the main body case 2 with the cylindrical sleeve grounded. Further, the photosensitive drum 20 is driven to rotate in the direction of arrow B by a driving unit (not shown).

The charger 30 is, for example, a scorotron type charger for positive charging that generates corona discharge from a charging wire made of tungsten or the like.

The laser scanner unit 40 includes a laser generator (not shown) for generating a laser beam L for forming an electrostatic latent image on the photosensitive drum 20, and a polygon mirror (pentahedral mirror) 41 that is driven to rotate. , A pair of lenses 42 and 4
3 and a pair of reflecting mirrors 44 and 45.

The developing device 50 has a toner storage chamber 53 in a case 51. The toner storage chamber 53 has an agitator 54 and a positively chargeable non-magnetic one-component developer having electrical insulation. Is stored. A developing chamber 56 for performing development is formed on the photosensitive drum 20 side of the toner storage chamber 53, and a supply roller 57 and a developing roller 58 as a developer carrier are rotatably supported. The toner 55 on the developing roller 58 is regulated to a predetermined layer thickness by a layer thickness regulating blade 59 as a layer thickness regulating member whose leading end is pressed against the developing roller 58, and is used for development.

The developing device 50 as described above includes a case 51
The laser beam printer 1 is configured as a detachable developing device cartridge, and can be replaced with a new developing device cartridge when the thickness regulating blade 59 is worn.

The transfer roller 60 is rotatably supported, and
It is made of a conductive foamed elastic body made of silicone rubber or urethane rubber. This transfer roller 60
Is configured to reliably transfer the toner image on the photosensitive drum 20 to the paper P by the applied voltage.

The fixing unit 70 is provided downstream of the photosensitive drum 20 in the transport direction of the sheet P indicated by an arrow A,
A heating roller 71 and a pressing roller 72 are provided. The toner image transferred onto the paper P is pressed while being heated, and
Is established.

A pair of transport rollers 73 and a discharge roller 74 for transporting the paper are provided on the downstream side of the fixing unit 70 in the transport direction, and a discharge tray 75 is provided on the downstream side of the paper discharge roller 74. ing.

In the laser beam printer 1 of the present embodiment as described above, the surface of the photosensitive drum 20 is
When the laser beam L modulated according to image information is emitted from the laser scanner unit 40, an electrostatic latent image is formed on the surface of the photosensitive drum 20.
The electrostatic latent image is visualized by the developing device 50 with the toner 55, and the visible image formed on the photosensitive drum 20 is transported by the photosensitive drum 20 to a transfer position. At the transfer position, the paper P is supplied via the feeder unit 10 and the registration rollers 14 and 15, and the visible image is transferred to the paper P by a transfer bias applied to the transfer roller 60. Note that the toner remaining on the photosensitive drum 20 after the transfer is collected by the developing roller 58 of the developing device 50 and is again used for development. As described above, the laser beam printer 1 of the present embodiment employs a so-called cleaner-less developing method. Next, the paper P is conveyed to the fixing unit 70, is nipped and conveyed by the heating roller 71 and the pressing roller 72 of the fixing unit 70, and the visible image on the paper P is pressed and heated to be fixed on the paper P. You.
Then, the sheet P is transported by a pair of conveying rollers 73 and a sheet discharging roller 74 to a sheet discharging tray 7 above the laser beam printer 1.
5 and the image forming operation is completed.

According to the laser beam printer 1 of the present embodiment, a good image can be formed by such an image forming operation. When a non-magnetic one-component toner is used as the toner 55 as described above, a thin layer of toner having a regular charge polarity and charge amount is stably formed on the surface of the developing roller 58 with a uniform layer thickness. Is generally difficult, but in the present embodiment, the developing device 5
Since 0 is configured as follows, such a problem is solved, and a high-quality image without density unevenness, insufficient density, or print fog is obtained. Hereinafter, the configuration of the developing device 50 in the present embodiment will be described.

FIGS. 2 to 4 show the developing device 50 of this embodiment.
Shown in 2 is a plan view of the developing device 50 as viewed from above in FIG. 1, FIG. 3 is a sectional view taken along line XX ′ in FIG. 2, and FIG. 4 is a sectional view taken along line YY ′ in FIG.

As shown in FIGS. 3 and 4, a developing roller 58 as a developer carrier is formed by forming a base member 58b made of conductive urethane rubber on a cored bar 58a made of stainless steel or the like. Further, a surface coat layer 58c made of resin or rubber containing fluorine is formed on the surface of the base material 58b in order to improve the chargeability of the urethane rubber. As the surface coat layer 58c, for example, Teflon, PFA, silicone rubber containing fluorine, or the like can be used. The surface has a ten-point average roughness (Rz) of 3 to 5 μm, which is smaller than 8 μm, which is the average particle diameter of the toner. The thickness of the surface coat layer 58c is set to be smaller than the average particle diameter of the toner of 8 μm, and is set to 5 to 6 μm as an example in the present embodiment. Further, a voltage is applied to the developing roller 58 from a power supply (not shown), and the developing roller 58 has a predetermined potential difference with the photosensitive drum 20. In this embodiment, a voltage of +600 V is applied by the power supply. Also,
The developing roller 58 is rotated in a direction shown in FIG.

Layer thickness regulating blade 5 as layer thickness regulating member
9 is made of stainless steel or the like as shown in FIG.
Supporting part 5 whose base end is fixed to case 51 of developing device 50
9a and a contact portion 59b provided at the tip of the support portion 59a and made of silicone rubber. The contact portion 59b is formed by the elastic force of the support portion 59a.
Is pressed against. As shown in FIGS. 3 and 4, the shape of the contact portion 59b is formed so that the cross section is a substantially semilunar convex shape.

As shown in FIG. 4, the supply roller 57 is provided with a sponge roller 57b made of conductive silicone rubber or urethane rubber on a metal core 57a made of stainless steel or the like so as to have a cylindrical shape. The sponge is arranged so as to be pressed against the roller 58 by the elastic force of the sponge. The supply roller 57 is rotated in the same direction as the developing roller 58 by driving means (not shown).

Below the developing roller 58, a toner seal sheet 52 made of a resin such as PET or a urethane rubber sheet is provided so as to elastically contact the surface of the developing roller 58 as shown in FIG. And the developing roller 58
To prevent toner from leaking from the bottom of the printer.

The toner 55 is a positively-charged non-magnetic one-component developer, and is a styrene-formed spherical toner formed by suspension polymerization.
A particle size of 6 μm to 1 obtained by adding a known colorant such as carbon black and a charge control agent such as nigrosine, triphenylmethane and quaternary ammonium salt to an acrylic resin.
The toner base particles have a particle diameter of 0 μm and an average particle diameter of 8 μm.
The toner 55 is configured by adding silica as an external additive to the surface of the toner base particles. The silica as the external additive is subjected to a well-known hydrophobic treatment with a silane coupling agent or the like, and two types of silica having a BET value of 100 or less and a BET value exceeding 100 are used. . In the present embodiment, as an example, silica having a BET value of 200 is added to the toner base particles at 0.6 weight (wt).
% And silica having a BET value of 50 was added in an amount of 1.0% by weight (wt) of the toner base particles.

Here, the BET value is a specific surface area measured by adsorbing nitrogen, and is represented by an area per unit weight (unit: m ² / g). Therefore, as the BET value increases, the particle size decreases, and as the BET value decreases, the particle size increases. In the present embodiment, a BET value is measured by a normal BET measurement method, and a specific surface area measurement device FlowSor manufactured by Shimadzu Corporation is used.
b2-2300 was used.

As shown in FIGS. 2 and 3, a toner seal member 80 for a developing roller as a developer sealing means formed of a urethane sponge is provided at both ends in the longitudinal direction of the developing roller 58. As shown in FIG. 3, the Teflon felt 81 is arranged as a rubbing portion for the developing roller 58 so as to press the peripheral surface of the developing roller 58 by the elastic force of the urethane sponge. The Teflon felt 81 is made by impregnating the felt with Teflon, and has a small frictional resistance. The Teflon felt 81 is attached to the urethane sponge of the toner seal member 80 with a double-sided tape. Further, the toner seal member 8
The other surface of the developing device 50 is also arranged so as to be in close contact with the case 51 of the developing device 50 by the elastic force of the urethane sponge. The width W of the toner seal member 80 shown in FIG. 3 is set to 70 mm to 100 mm in the present embodiment.

Further, at both ends in the longitudinal direction of the layer thickness regulating blade 59, as shown in FIGS. 2 and 3, toner seal members 81 for the layer thickness regulating blade formed of urethane sponge are provided. , The toner seal member 81
Are the support portion 59b of the layer thickness regulating blade 59, the toner seal member 80 for the developing roller 58, and the developing device 5
The case 51 is disposed so as to be in close contact with the urethane sponge due to the elastic force of the urethane sponge.

As described above, the developing device 50 of this embodiment uses a suspension polymerization toner having an extremely spherical shape as a non-magnetic one-component developer, and has a BET value of 200 0.6% by weight and 1.0% by weight of a silica having a large particle diameter having a BET value of 50 are added as an external additive. The development can be performed with a toner which is prevented by an external additive having a particle diameter and exhibits extremely good fluidity even when used for a long period of time, in combination with the function of the external additive having a small particle diameter. As a result, a sufficient charge amount can be obtained by frictional charging, so that an image with excellent transfer efficiency and extremely high image quality can be formed. Furthermore, in the present embodiment, the contact portion 5 of the layer thickness regulating blade 59
By forming silicone rubber 9b with silicone rubber, the charge-imparting performance for the toner can be remarkably improved, and extremely good triboelectric charging can be performed in combination with the extremely polymerizable suspension polymerization toner.

Further, when the polymerized toner having good fluidity is used, toner leakage is likely to occur, and once toner leakage occurs, a larger amount of toner is used as compared with the case where pulverized toner is used. Toner leaks, laser beam printer 1
Inside the developing device 50,
As described above, the toner seal members 80 made of urethane sponge are provided on both ends in the longitudinal direction of the developing roller 58, and the urethane sponge is also provided on both ends in the longitudinal direction of the layer thickness regulating blade 59. Since the toner seal member 81 is provided, it is possible to reliably prevent the polymerized toner having good fluidity from leaking from the developing device 50 as described above.

However, as in this embodiment, the developing roller 58
In the case where the toner sealing method in which the toner seal member 80 is adhered to the peripheral surface of the developing roller 58 is adopted, the polymerized toner may slightly enter between the peripheral surface of the developing roller 58 and the toner seal member 80. However, as described above, the developing roller 58 in the developing device 50 of the present embodiment
Since the base material 58b is formed of urethane rubber having excellent mechanical strength, even if the polymerized toner enters between the peripheral surface of the developing roller 58 and the toner seal member 80, the polymerized toner is used. Base material 5 of developing roller 58
The amount by which 8b is scraped is extremely small as compared with the case where the base material is made of silicone rubber. Therefore, unlike the conventional developing device, toner does not leak from the shaved portion.

When an external additive having a large particle size having a BET value of 100 or less is used as the external additive, the external additive having a large particle size acts as an abrasive, so that the above-mentioned polymerized toner is used. Although the shaving of the developing roller 58 becomes remarkable, in the present embodiment, since the base member 58b of the developing roller 58 is formed of urethane rubber having excellent mechanical strength, the BET
Even when an external additive having a large particle diameter of 100 or less is used, the base material 58b is not scraped by the external additive having a large particle diameter so as to cause toner leakage, thereby reliably preventing toner leakage. be able to.

Further, in the developing device 50 of the present embodiment, since the rubbing portion of the toner seal member 80 against the peripheral surface of the developing roller 58 is formed from the Teflon felt 81 as described above, the toner is The toner seal member 80 is pressed with a sufficient pressing force so as not to enter between the peripheral surface of
8 is rubbed. Even in such a configuration, the frictional resistance of the Teflon felt 81 to the developing roller 58 is extremely small, so that the rotational torque of the developing roller 58 does not become too high, and no high-temperature heat is generated due to the friction. . As described above, in the present embodiment, by increasing the pressing force of the toner seal member 80 against the developing roller 58, the leakage of the toner is more reliably prevented. Further, when the pressing force of the toner seal member 80 against the developing roller 58 is increased, when the polymerized toner enters between the developing roller 58 and the toner seal member 80, the shaving of the developing roller 58 by the polymerized toner is promoted. However, in the developing device 50 of the present embodiment, as described above, since the base member 58b of the developing roller 58 is formed of urethane rubber having excellent mechanical strength, the toner seal is formed as described above. Even when the pressing force of the member 80 against the developing roller 58 is increased, the base material 58b of the developing roller 58 is not abraded by the polymerized toner that has entered the gap so that toner leakage occurs.

As described above, in the present embodiment, since the base member 58 of the developing roller 58 is formed of urethane rubber, it is possible to reliably prevent the developing roller 58 from being scraped by the polymerized toner or the external additive. Since the urethane rubber has a low charge-imparting ability to the toner, a sufficient amount of charge may not be imparted to the toner. However, in the developing device 50 of the present embodiment, since the surface coat layer 58c containing fluorine is formed as a surface layer of the base material 58b of the developing roller 58, the chargeability of the urethane rubber is reduced by the surface coat layer 58c. And sufficient and appropriate triboelectric charge can be imparted to the toner. The configuration of the surface coat layer 58c is not limited to the one containing fluorine, but in the present embodiment, since the toner to be used is a positively chargeable toner, such a surface coat layer 58c is used. Using.

The mechanical strength of the surface coat layer 58c is inferior to that of urethane rubber.
If the polymerized toner enters between the toner seal member 8 and the toner seal member 80, the surface coat layer 58c will be scraped off after a relatively short use. However,
Since the base material 58b, which is the lower layer of the surface coat layer 58c, is made of urethane rubber having excellent mechanical strength as described above, such scraping by the polymerized toner does not affect the surface coat layer 58c. It can be limited to only. Further, in the present embodiment, since the layer thickness of the surface coat layer 58c is set to 5 to 6 μm, which is smaller than the average particle diameter of the toner of 8 μm, the surface coat layer 58c is temporarily scraped. Even in this case, the size of the gap generated by the shaving is smaller than that of the toner having an average particle diameter, so that toner leakage can be reduced.

As described above, according to the developing device of the present embodiment, it is possible to maintain good developing performance for a long period of time while reliably preventing toner leakage of the polymerized toner. In the above, an example using an external additive having a BET value of 200 and an external additive having a BET value of 50 has been described.
The present invention is not limited to such a configuration, and it is sufficient that at least one external additive has a BET value of 100 or less.

Alternatively, a predetermined voltage may be applied to the layer thickness regulating blade 59 by a power supply to prevent passage of toner of opposite polarity or uncharged toner.

The present invention also relates to an image forming apparatus such as a copying machine for forming an electrostatic latent image by a laser beam L in accordance with a read document image. The present invention can be similarly applied to an image forming apparatus using a non-magnetic one-component developer, for example, an image forming apparatus using another polymerized toner obtained by emulsion polymerization or the like. Even when the toner has such a configuration, relatively good fluidity can be obtained, and similar effects can be obtained although the toner 55 is slightly inferior.

[0052]

As described above, according to the image forming apparatus of the first aspect, the developer sealing means provided so as to be in pressure contact with the peripheral surfaces at both ends in the longitudinal direction of the developer carrier. Since the polymerized toner obtained by the polymerization method and the developer carrier having at least the base material formed of conductive urethane rubber are used, very good development is performed by the polymerized toner having extremely high fluidity. At the same time, it is possible to reliably prevent the polymerized toner having good fluidity from leaking. what if,
Even when the polymerized toner slightly enters the pressure contact portion between the developer carrier and the developer sealing means, at least the base material is formed of conductive urethane rubber having excellent mechanical strength. As a result, the toner is not easily scraped off by the polymerized toner to which the external additive has been added, and a gap due to the scraping to such an extent as to cause toner leakage at the pressure contact portion with the developer sealing means does not occur. Therefore, the toner can be reliably sealed, and the occurrence of toner leakage can be prevented.

According to the developing device of the present invention, since the developer carrier has a surface coat layer formed on a base material made of conductive urethane rubber, the developer carrier can be provided on the developer carrier. A desired chargeability or surface roughness can be provided. Even if the polymerized toner slightly enters the pressure contact portion between the developer carrier and the developer sealing means, the developer carrier is at least a base made of conductive urethane rubber having excellent mechanical strength. Even if the surface coat layer is shaved by the polymerized toner to which an external additive is added, the surface coat layer is shaved enough to cause toner leakage at a pressure contact portion with the developer sealing means. No gaps are created. Therefore, the toner can be reliably sealed, and the occurrence of toner leakage can be prevented.

According to the third aspect of the present invention, since the surface coat layer of the developer carrying member is a layer which has been subjected to a surface treatment for improving the chargeability of the surface of the developer carrying member, it is possible to charge the developer. Even when urethane rubber having inferior properties is used as the base material of the developer carrying member, the developer can be satisfactorily triboelectrically charged. Even if the polymerized toner slightly enters the pressure contact portion between the developer carrying member and the developer sealing means, at least the base material of the developer carrying member is a conductive material having excellent mechanical strength. Even if the surface coat layer is shaved by the polymerized toner to which an external additive has been added, toner leakage occurs at the pressure contact portion with the developer sealing means because the surface coat layer is shaved by the urethane rubber. It does not create gaps due to the slight scraping. Therefore, the toner can be reliably sealed, and the occurrence of toner leakage can be prevented.

According to the fourth aspect of the present invention, the layer thickness of the surface coat layer of the developer carrier is formed to be smaller than the average particle diameter of the polymerized toner. Even if the polymerized toner slightly enters the pressure contact portion between the carrier and the developer sealing means and the surface coat layer is scraped, the layer thickness of the surface coat layer is the average particle diameter of the polymerized toner. Since it is formed so as to have a smaller value, it is possible to reliably prevent toner from leaking from the shaved portion of the surface coat layer.

According to the developing device of the present invention, at least two types of external additives having different sizes are added to the polymerized toner as a developer, and at least one of the external additives is added.
Since the external additive having a BET value smaller than 100 is used, the fluidity of the polymerized toner can be further improved by the external additive having a small particle diameter, and the toner of the external additive having the small particle diameter can be further improved. Embedding into the base particles can be reliably prevented. Such BET value is 10
An external additive smaller than 0 can be an abrasive, but since the developer carrier is at least a base made of conductive urethane rubber, it is reliably prevented from being scraped by the external additive having a large particle size, and the toner Leakage can be reliably prevented.

According to the sixth aspect of the present invention, since at least a portion of the developer sealing means that is in pressure contact with the developer carrier is formed of Teflon felt, the frictional resistance to the developer carrier is reduced. Even when the developer sealing means is rubbed against the developer carrier with sufficient pressure so that toner does not enter between the developer carrier and the developer sealing means, It is possible to prevent the rotation torque from becoming too high. Further, generation of high heat due to friction can be suppressed. When the pressing force of the developer sealing means is strong, the toner enters between the developer carrying member and the developer sealing means, thereby facilitating the scraping of the developer carrying member.
Since at least the base material of the developer carrying member is formed of urethane rubber, even when the developer sealing means is strongly pressed, the shaving of the developer carrying member can be reduced, and toner leakage can be surely prevented. Can be prevented.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a schematic configuration of an image forming apparatus according to an embodiment of the present invention.

FIG. 2 is a plan view illustrating a schematic configuration of a developing device in the image forming apparatus of FIG.

FIG. 3 is a sectional view of the developing device taken along line XX ′ in FIG. 2;

FIG. 4 is a sectional view taken along line YY ′ of the developing device in FIG. 2;

[Explanation of symbols]

 Reference Signs List 50 developing device 55 toner 58 developing roller 58b base material 58c surface coat layer 59 layer thickness regulating blade 80 toner seal member 81 Teflon felt

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G03G 9/087 G03G 9/08 384 F term (Reference) 2H005 AA08 AB06 CA26 CB13 EA05 EA10 FA07 2H077 AC04 AD06 AD13 AD17 AE04 BA01 CA12 EA14 FA12 FA22 FA25 3J103 AA02 AA14 AA51 FA30 GA02 GA52 HA03 HA04 HA12 HA18 HA20 HA22 HA43 HA53

Claims (6)

[Claims] 1. A layer thickness regulating member is pressed against a peripheral surface of a developer carrier for carrying and transporting a non-magnetic one-component developer, and the developer is passed through the pressed portion to form a thin layer of the developer. A developing device that transports a thin layer of the developer to a development area by the developer carrier to perform development, and is provided so as to be in pressure contact with the peripheral surfaces of both ends in the longitudinal direction of the developer carrier. Provided, wherein the developer is a polymerized toner obtained by a polymerization method, and the developer carrier has at least a base material formed of conductive urethane rubber. Developing device. 2. The developing device according to claim 1, wherein the developer carrier has a surface coat layer on the substrate formed of the conductive urethane rubber. 3. The developing device according to claim 2, wherein the surface coat layer of the developer carrier is a layer that has been subjected to a surface treatment for improving the chargeability of the surface of the developer carrier. 4. The method according to claim 1, wherein the thickness of the surface coat layer of the developer carrier is formed to be smaller than the average particle diameter of the polymerized toner. 4. The developing device according to claim 3. 5. The developer has at least two types of external additives having different sizes added to the polymerized toner, and at least one of the external additives has a BET value of 100.
The developing device according to claim 1, wherein the external additive is smaller. 6. The developer sealing means according to claim 1, wherein at least a portion of the developer sealing means which is in pressure contact with the developer carrier is made of Teflon felt.
The developing device according to claim 1.