JP2000206778A - Toner carrier and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a toner carrier capable of surely and stably obtaining a high-quality image without causing image change due to time passage or image irregularity, at the time of consecutive printing or in partial solid image printing without causing white image fogging. SOLUTION: As for this toner carrier, the absolute value of surface potential attenuating speed attained until 0.2 seconds elapse after imparting charge in the case of electrifying the surface of the toner carrier by applying 8 kV voltage to a corona discharger arranged at the distance of 1 mm from the surface thereof so that corona discharge generated is >=0.1 [V/sec]. The toner carrier in this method is a roller obtained by forming a semiconductive layer 3 on the outer periphery of a good conductive shaft 2 and further forming a resin covering layer 3a on the layer 3 as necessary, such as a roller 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used as a developing roller for visualizing an electrostatic latent image with a non-magnetic one-component developer in an electrophotographic apparatus such as a copying machine or a printer or an electrostatic recording apparatus. The image forming apparatus such as a toner carrier and a developing device using the toner carrier is described in further detail.Image change over time even during continuous printing or partial solid image printing without occurrence of white image fog. The present invention relates to a toner carrier capable of obtaining a high-quality image without causing image unevenness, and an image forming apparatus using the toner carrier.

[0002]

2. Description of the Related Art Conventionally, in an electrophotographic image forming apparatus such as a copying machine or a printer, a non-magnetic one-component developer is supplied to a photosensitive drum or the like holding a latent image and the developer is supplied to the latent image on the photosensitive drum. A pressure development method is known as a development method for visualizing a latent image by adhering a toner (US Pat. No. 3,515,2012).
According to this method, since a magnetic material such as a carrier is not required, the apparatus can be simplified,
It is easy to miniaturize, and can handle color images because it does not contain magnetic powder.

In this pressure development method, a developing roller (toner carrier) carrying a toner (non-magnetic one-component developer) is a latent image carrier (image forming body) holding an electrostatic latent image such as a photosensitive drum. The development is carried out by bringing toner into contact with the latent image on the latent image holding member by contacting the developing roller. Therefore, it is necessary to form the developing roller with an elastic material having conductivity.

That is, in this pressure development method, as shown in FIG. 4, for example, a toner coating roller 4 for supplying toner and a photosensitive drum (image forming body) 5 holding an electrostatic latent image. Between the developing roller (toner carrier) 1
The toner 6 is supplied to the surface of the developing roller 1 by the toner applying roller 4 by rotating the developing roller 1, the photosensitive drum 5, and the toner applying roller 4 in the direction of the arrow in the drawing, respectively. The toner is arranged in a uniform thin layer by the stratification blade 7, and the developing roller 1 is rotated while being in contact with the photosensitive drum 5 in this state, so that the toner formed in the thin layer is transferred from the developing roller 1 to the photosensitive drum 5. The latent image is made visible by adhering to the image. In the drawing, reference numeral 8 denotes a transfer unit, which transfers a toner image to a recording medium such as paper. Reference numeral 9 denotes a cleaning unit, which is provided on the surface of the photosensitive drum 5 after transfer by a cleaning blade 10. The remaining toner is removed.

In this case, the developing roller 1 includes a photosensitive drum 5
It is necessary to rotate while securely maintaining a state of being in close contact with the shaft. Therefore, as shown in FIG.
It has a structure in which a semiconductive elastic body in which carbon black or metal powder is dispersed in an elastomer such as NBR, EPDM, ECO, polyurethane or the like, or a semiconductive layer 3 made of a foam body formed by foaming them. Further, a coating layer 3a made of resin or the like is formed for the purpose of controlling the chargeability and adhesion of the toner, controlling the frictional force between the developing roller and the layering blade, and preventing the photosensitive member from being contaminated by the elastic body of the developing roller. It may be formed on the surface.

Further, there has been proposed a method of forming an image by directly flying toner carried on the surface of a toner carrier through a perforated control electrode onto paper or OHP paper.

In these toner carriers, the resistance of the carrier itself is adjusted to about 10 ⁵ to 10 ⁹ Ω in order to obtain an electric field which serves as a driving force for transferring the carried toner to an image forming body such as a photoreceptor. You. In many cases, the resistance of the resin coating layer 3a covering the surface is set higher than that of the semiconductive elastic layer 3 to facilitate resistance adjustment. in this case,
As in the case of the semiconductive elastic layer 3, carbon black, metal powder, metal oxide, or the like is used for adjusting the resistance of the resin coating layer 3a.

[0008]

To consider an electrophotographic system using the developing roller (toner carrier) 1 described above,
In particular, in order to obtain a high-quality image, it is required that the developer held on the developing roller always keeps a constant charge when reaching the image forming body and has a uniform charging state.

That is, when high image quality is required for an image forming apparatus such as a printer or when an attempt is made to cope with a color image, the charge amount of the toner carried on the developing roller is unstable during continuous printing. For example, frictional charging of the toner on the developing roller in the last developing portion may occur continuously, and the charging amount may exceed a predetermined value.
Also, when a black solid image is printed partially, for example, the charge amount of the developer newly held in that portion may be different from that of the surroundings, and this may cause non-uniformity of the developer charge distribution and the like. A uniform image defect may occur.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and does not cause white image fogging and does not cause image change or image unevenness over time even in continuous printing or partial solid image printing. It is an object to provide a toner carrier capable of reliably and stably obtaining a stable image and an image forming apparatus using the toner carrier.

[0011]

Means for Solving the Problems and Embodiments of the Invention The present inventors have conducted intensive studies in order to obtain a toner carrier capable of forming a high-quality image which can sufficiently cope with a color image. As a result, the electrical resistance between the metal shaft and the surface, which has been regarded as important in the conventional developing roller (toner carrier), is controlled to a constant value over the entire surface of the roller and is not only uniform, but also the charging characteristics of the toner. The uniformity of the surface resistance on the developing roller, which controls the toner density, prevents uneven density and fogging of white images, and found that high-quality images can be formed. By setting the residual charge decay rate on the roller surface to a certain value or more, uniform toner charging can be obtained even in continuous printing or partial image printing, and high-quality images can be reliably obtained. It found Rukoto.

Therefore, the present inventor further studied the evaluation of a proper electric resistance value and a good surface charge decay rate of the toner carrier. As a result, the corona discharger arranged at a distance of 1 mm from the surface of the toner carrier was examined. When a voltage of 8 kV is applied to the electric appliance to generate corona discharge to charge the surface, the absolute value of the surface potential decay rate from the time of charge application to 0.2 seconds after is 0.1 [V / sec] or more. By controlling so that the density unevenness and the fog of the white image can be prevented as much as possible, and the good image quality can be surely maintained even in the continuous printing or the partial image printing. The inventors have found that a high-quality image capable of coping with an image can be obtained reliably and stably, and the present invention has been completed.

Accordingly, the present invention comprises a semiconductive layer formed on the outer periphery of a highly conductive shaft, a nonmagnetic one-component developer carried on the surface to form a thin layer of the developer, and in this state, A corona disposed at a distance of 1 mm from the surface of a toner carrier that forms a visible image on the image forming body by supplying the developer to the surface of the image forming body in contact with or in close proximity to the image forming body; When a voltage of 8 kV is applied to the discharger to generate corona discharge and charge the surface, the absolute value of the surface potential decay rate from the time of charge application to 0.2 seconds after is 0.1 [V / sec] or more. It is intended to provide a toner carrier characterized by the following.

Hereinafter, the present invention will be described in more detail.
The toner carrier of the present invention is, for example, a roller as shown in FIG.
As shown in FIG. 1, a semiconductive layer 3 is formed on the outer periphery of the good conductive shaft 2, and a resin coating layer 3a is further formed on the semiconductive layer 3 if necessary. When a voltage of 8 kV is applied to a corona discharger disposed at a distance of 1 mm from the surface of the toner carrier to generate a corona discharge, the surface of the toner carrier is charged. The absolute value of the surface potential decay rate after 0.1 second was set to 0.1 [V / sec] or more.

As the shaft 2, any shaft having good conductivity can be used. Usually, the shaft 2 is made of a metal such as iron, stainless steel, aluminum or the like. A metal shaft such as a metal cylinder having a hollow or hollow inside is used.

Next, the semiconductive layer 3 formed on the outer periphery of the shaft 2 is formed by blending an electronic conductive agent such as carbon black or an ionic conductive agent such as sodium perchlorate into a single elastomer or a foam obtained by foaming the elastomer. It is formed of a semiconductive elastic body whose resistance value is adjusted.

Examples of the above-mentioned elastomer include silicone rubber, EPDM, NBR, natural rubber, SBR, butyl rubber, chloroprene rubber, acrylic rubber, epichlorohydrin rubber, EVA, polyurethane, and mixtures thereof. , EPDM and epichlorohydrin rubber polyurethane are preferably used. Further, these elastomers can be foamed chemically using a foaming agent, or can be used as a foam body formed by foaming by mechanically entraining air like polyurethane foam.

Examples of the conductive agent to be incorporated in the semiconductive layer 3 include an electronic conductive agent, for example, conductive carbon such as Ketjen black and acetylene black;
F, ISAF, HAF, FEF, GPF, SRF, F
Rubber carbon such as T, MT, etc., carbon for color (ink) subjected to oxidation treatment, pyrolytic carbon, natural graphite, artificial graphite, antimony-doped tin oxide, titanium oxide, zinc oxide, nickel, copper, silver And metals such as germanium and metal oxides, and conductive polymers such as polyaniline, polypyrrole, and polyacetylene. The amount of these electronic conductive agents is usually 1 to 50 parts by weight, especially 5 to 4 parts by weight, per 100 parts by weight of the elastomer.
It is suitably used in the range of 0 parts by weight.

Examples of the ionic conductive agent include perchlorates, chlorates, and hydrochloric acids such as tetraethylammonium, tetrabutylammonium, dodecyltrimethylammonium, hexadecyltrimethylammonium, benzyltrimethylammonium, and modified fatty acid dimethylethylammonium. Ammonium salts such as salts, bromates, iodates, borofluorides, sulfates, ethyl sulfates, carboxylates, sulfonates; alkali metals such as lithium, sodium, potassium, calcium, magnesium; Examples include alkaline earth metal perchlorates, hydrochlorides, bromates, iodates, borofluorides, sulfates, and the like. The compounding amount of these ionic conductive agents is generally suitably used in the range of 0.01 to 5 parts by weight, particularly 0.05 to 2 parts by weight, based on 100 parts by weight of the elastomer.

The conductive agent may be used alone or in combination of two or more. In this case, an electronic conductive agent and an ionic conductive agent can be combined.

The semiconducting layer 3 is not particularly limited, but has a resistance of 10 due to the blending of the above conductive agent.
It is preferably from ³ to 10 ¹⁰ Ωcm, particularly preferably from 10 ⁴ to 10 ⁸ Ωcm. If the resistance value is less than 10 ³ Ωcm, electric charges may leak to the photosensitive drum or the like, or the toner carrier itself may be broken by the voltage. On the other hand, if the resistance value exceeds 10 ¹⁰ Ωcm, fogging tends to occur. .

A cross-linking agent and a vulcanizing agent can be added to the semiconductive layer 3 if necessary to convert the elastomer into a rubbery substance. In this case, in any case of organic peroxide crosslinking and sulfur crosslinking, a vulcanization aid, a vulcanization accelerator,
Vulcanization accelerators, vulcanization retarders and the like can be used. Furthermore, peptizing agents, foaming agents, plasticizers, softeners, tackifiers, antiblocking agents, separating agents, release agents, extenders, and coloring agents that are commonly used as rubber compounding agents in addition to the above. Etc. can be added.

Further, when the conductive layer 3 is formed by using polyurethane or EPDM as a base material, nigrosine, triaminophenylmethane, cationic dye, and the like are used for controlling the amount of toner charge on the surface when used as a developing roller. And various fine particles such as silicone resin, silicone rubber and nylon. In this case, the amount of these additives is preferably 1 to 5 parts by weight, and the fine powder is preferably 1 to 10 parts by weight, based on 100 parts by weight of the polyurethane or EPDM.

The hardness of the semiconductive layer 3 is not particularly limited, but is not more than 60 ° on a JIS-A scale.
Particularly, it is preferable to set the angle to 25 to 55 °. In this case, if the hardness exceeds 60 °, for example, when used as a developing roller, the contact area with the photosensitive drum or the like becomes small, and there is a possibility that good development cannot be performed. Further, the toner is damaged, and the toner adheres to the photoreceptor or the layered blade, and the image is likely to be defective. Conversely, if the hardness is too low, the frictional force between the photoconductor and the stratification blade increases, and image defects such as jitter may occur. In addition, since the semiconductive layer 3 is used in contact with a photoreceptor, a laminating blade, or the like, it is preferable that the compression set be as small as possible even when the hardness is set to a low hardness. % Is preferable.

Although the surface roughness of the semiconductive layer 3 is not particularly limited, it is 15 μm in JIS 10 point average roughness.
mRz or less, particularly preferably 1 to 10 μmRz. If the surface roughness exceeds 15 μmRz, the thickness of the toner layer of the one-component developer (toner) and the uniformity of charging may be impaired.
The adhesion of the toner can be improved, and the deterioration of the image due to the wear of the roller during long-term use can be more reliably prevented.

As shown by a dashed line in FIG. 1, the toner carrier of the present invention has a resin coating layer 3a on the semiconductive layer 3 in order to adjust the resistance and control the amount of toner charge and the amount of conveyance.
Can be formed. The resin forming the resin coating layer is not particularly limited, and may be any resin that is non-staining and does not adhere to an image forming body such as a photosensitive drum. Specifically, polyester resin, polyether resin, fluorine resin, epoxy resin, amino resin, polyamide resin, acrylic resin, acrylic urethane resin, urethane resin, alkyd resin, phenol resin, melamine resin, urea resin, silicone resin, polyvinyl resin Butyral resin and the like can be mentioned, and one or more of these can be used in combination. Further, modified resins in which a specific functional group is introduced into these resins can also be used.

The resin coating layer 3a may contain a conductive agent for the purpose of controlling its conductivity. The conductive agent may be the same as the conductive agent used in the semiconductive layer 3 described above. Things can be exemplified. In order to improve the mechanical strength and environmental resistance of the resin coating layer 3a, it is preferable to introduce a crosslinked structure. in this case,
In order to introduce a cross-linked structure, a self-cross-linking method of cross-linking with heat, a catalyst, air (oxygen), moisture (water), ultraviolet light, or the like, depending on the molecular structure of the resin constituting the resin coating layer 3a, a cross-linking agent, There is another method of causing a crosslinkable resin reaction.

It should be noted that various other additives can be added to the resin coating layer 3a as needed.

As a method for forming the resin coating layer 3a on the semiconductive layer 3, a method in which the surface of the semiconductive layer 3 is treated with a resin solution containing the resin component and the additive is suitably adopted. . In this case, after preparing the resin solution, the surface treatment can be performed by a spray method, a roll coater method, a dipping method, or the like. The solvent for preparing the resin solution may be any solvent as long as it dissolves the resin, but is usually methanol, ethanol, lower alcohols such as isopropanol, acetone,
Ketones such as methyl ethyl ketone and cyclohexanone,
Toluene, xylene and the like are preferably used.

Although the thickness of the resin coating layer 3a is not particularly limited, it is usually 3 to 50 μm, particularly 5 to 30 μm.
If the thickness is less than 3 μm, it may not be possible to secure sufficient charging performance on the surface due to abrasion during durability. On the other hand, if it exceeds 50 μm, the surface of the toner carrier becomes hard. When the toner is damaged, the toner may adhere to an image forming body such as a photoreceptor or a layered blade, resulting in an image defect.

Although the toner carrier of the present invention is not particularly limited, it has an electric resistance of 10 ⁴ to 100 V when applied.
It is preferably 10 ¹⁰ Ω, particularly preferably 10 ⁵ to 10 ⁹ Ω.
In this case, if the resistance value is less than 10 ⁴ Ω, gradation control may become extremely difficult, and if an image forming member such as a photoreceptor has a defect, a bias leak may occur. On the other hand, when the resistance exceeds 10 ¹⁰ Ω, for example, when developing the toner on a latent image holding member such as a photoconductor, the developing bias causes a voltage drop due to the high resistance of the toner holding member itself, and the developing bias is insufficient. Without being able to secure the developing bias,
In some cases, a sufficient image density cannot be obtained. The resistance value can be measured, for example, by pressing the toner carrier against a flat or cylindrical counter electrode at a predetermined pressure, applying a voltage of 100 V between the shaft and the counter electrode, and measuring the current value at that time. it can.

As described above, it is important to properly and uniformly control the resistance value of the toner carrier in order to maintain the electric field strength for toner movement properly and uniformly. This is a necessary condition but not a sufficient condition to make the charge amount appropriate and uniform. That is, according to the study of the present inventor, in addition to this resistance value, it is necessary to control the charge holding ability of the surface of the toner carrier and to keep the same uniform, and furthermore, the surface residual potential attenuates at a constant speed. It was found to be important for the optimization and homogenization of the material. In this case, the surface charge holding ability is examined by measuring a surface resistance by arranging a pair of electrodes on the surface of the toner carrier and applying a constant voltage between the two electrodes. Since it does not only flow through the carrier but also flows inside the carrier, accurate evaluation of the carrier surface cannot be performed. Although improvement in accuracy by the four-terminal method has also been proposed, particularly in the case of a laminated toner carrier, the surface layer is quite thin, and it is difficult to characterize only the surface in this method. is there. Therefore, the characteristic values obtained by these conventional measurement methods cannot accurately represent the surface charge holding ability.

Therefore, in the present invention, at 22 ° C. and 50% RH
In the side environment, a voltage of 8 kV was applied to a corona discharger arranged at a distance of 1 mm from the surface of the toner carrier to generate a corona discharge and charge the surface in 0.2 seconds from the charge application. The surface charge retention ability is evaluated based on the absolute value of the surface potential decay rate until later, and the absolute value of the surface potential decay rate is set to 0.1 [V / sec] or more. In this case, the absolute value of the surface potential decay rate is 0.1
If it is less than [V / sec], the surface charge gradually accumulates during continuous operation, and the toner charge amount on the toner carrier exceeds a predetermined value. When the potential exceeds the body white background portion, a high voltage fog occurs on the white background printing portion. Further, in some cases, when the electric field generated by charging the toner exceeds a maximum value, discharge occurs between the toner and an image forming body such as a photoconductor, and an image defect may occur. The polarity charged by corona discharge may be either positive or negative. In the present invention, the absolute value of the decay rate of the surface potential due to corona charging may be 0.1 [V / sec] or more.

Here, the attenuation of the potential on the surface of the toner carrier will be briefly described. Normally, the charge decay curve is calculated at time t
[Sec] When a logarithm logV of the surface potential is plotted, a linear relationship is derived, and the relaxation time (time constant) can be set from the slope of the straight line. However, the attenuation curve of the actual toner carrier does not have a linear relationship as shown in FIG. This may be because the decay time constant indicates the voltage dependence of the residual surface potential. Here, for example, the rotational peripheral speed of the developing roller is about 0.4 sec / 1 rotation in many cases, and the charge decay rate in an extremely short time is considered to be an important characteristic. The time from the removal to the scraping by the toner application roller is about 0.2 sec. Therefore, the surface potential decay rate from 0.2 seconds after the surface is charged is a particularly important characteristic.

Here, in the present invention, non-contact corona charging is used as means for applying a predetermined charge to the surface of the toner carrier, and in this charging method, the initial charging potential V =
It is difficult to identify 0. Therefore, in the actual measurement, the decay rate [V / sec] of the surface potential from 0.1 sec to after 0.2 sec may be measured, and this decay rate may be controlled. In addition, as a calculation method of the decay rate,
The value of the surface potential after 0.1 sec is set as the initial value,
It is possible to adopt a method of linearly approximating the value of the surface potential until after ec by the method of least squares and calculating the surface potential decay rate from the slope.

The application of charge to the toner carrier and the measurement of the surface potential can be performed by, for example, the apparatus shown in FIG. That is, a measurement in which both ends of the shaft 2 of the toner carrier 1 are gripped by the chuck 11 to support the toner carrier 1, and the small corotron discharger 12 and the surface voltmeter 13 are juxtaposed at a predetermined interval. The unit is disposed opposite to the surface of the toner carrier 1 with a gap of 1 mm, and the measuring units 12 and 13 are fixed from one end to the other end of the toner carrier 1 while the toner carrier 1 is kept stationary. A method of measuring the surface potential while giving a surface charge by moving at a speed is suitably adopted.

The toner carrier of the present invention can be incorporated in an image forming apparatus such as a developing apparatus using a non-magnetic one-component developer, and more specifically, as shown in FIG. The toner carrier of the present invention is disposed as a developing roller 1 in contact with or in proximity to the photosensitive drum 5 between the coating roller 4 and the photosensitive drum 5 holding the electrostatic latent image. The toner 6 is supplied to the developing roller 1, which is formed into a uniform thin layer by a layering blade 7, and the toner is supplied from the thin layer to the photosensitive drum 5, and the toner is applied to the electrostatic latent image on the photosensitive drum 5. The latent image can be visualized by attaching it. Since the details of FIG. 2 have been described in the related art, the description thereof is omitted.

In addition to such a developing device,
For example, the image forming apparatus is preferably used in an image forming apparatus that forms an image by directly flying toner carried on a toner carrier through an aperture-shaped control electrode on an image forming body made of paper sheets. .

[0039]

EXAMPLES The present invention will be described in detail below with reference to examples and comparative examples, but the present invention is not limited to the following examples.

Examples 1 and 2 and Comparative Examples 1 and 2 Propylene oxide and ethylene oxide were added to glycerin to give 100 parts (parts by weight, hereinafter the same) of polyether polyol (OH value 33) having a molecular weight of 5000. , 1,
1.0 part of 4-butanediol, 1.5 parts of a silicone surfactant, 0.5 parts of nickel acetylacetonate, 0.01 parts of dibutyltin dilaurate and 0.01 parts of sodium perchlorate are added, and the mixture is mixed. By mixing, a polyol composition was prepared.

After the polyol composition was stirred and defoamed under reduced pressure, 17.5 parts of urethane-modified MDI was added, stirred for 2 minutes, and then poured into a mold heated to 110 ° C. After curing, an elastic layer was formed on the outer periphery of the metallic shaft to obtain a roller having the structure shown in FIG. The surface of the obtained roller is polished and the surface is JIS 10 point average roughness 7μ.
Adjusted to mRz.

The resin shown in Table 1 below was dissolved in methyl ethyl ketone (MEK), and the conductive agent shown in Table 1 was further added to prepare a paint. The roller was immersed in the paint, and then pulled up. , Heated and dried to form a resin coating layer, and the four types of developing rollers (toner carrier) shown in Table 1
I got The thickness of the resin coating layer was adjusted by adjusting the resin concentration in the paint as follows. Example 1
25%, Example 2: 10%, Comparative Example 1: 20%, Comparative Example 2: 25%.

With respect to each of the obtained developing rollers (toner carrier), the resistance value when a voltage of 100 V was applied between the developing roller (toner carrier) and the counter electrode (metal drum) was measured using the rotational resistance measuring device shown in FIG. did. Table 1 shows the results.

Also, using the apparatus shown in FIG. 2, a voltage of 8 kV was applied to the roller to charge the roller surface by corona discharge, and the measuring units 12 and 13 were set to 200 mm / sec.
The substrate was moved at the speed of c, charged with corona, and the surface potential was measured until 0.2 seconds later. The shape and dimensions of the measurement unit are as shown in FIG. By this method, the entire surface of the roller was measured, and 0.1 to 0.1 seconds after the corona charging.
The surface potential decay rate up to 2 seconds later was determined. Table 1 shows the results
Shown in The measurement environment was controlled at a temperature of 22 ° C. and a humidity of 50%.

Next, each roller is used as a developing roller 1 in FIG.
The image was mounted on the developing device (image forming device) shown in (1) and developed (image formation), and the obtained image was evaluated. Table 1 shows the results.

[0046]

[Table 1] * 1: "Printex 35" manufactured by Degussa * 2: Resin comparison

As is evident from the results shown in Table 1, the surface potential decay rate until 0.2 seconds after corona charging was adjusted to 0.1 [V / sec] or more. It was confirmed that the roller can reliably form a good image.

[0048]

As described above, according to the toner carrier of the present invention and the image forming apparatus using the same, image defects such as spots, uneven density, and occurrence of white image fog are minimized. Thus, a high-quality image can be reliably obtained.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing an example of the toner carrier of the present invention.

FIG. 2 is a schematic diagram illustrating an example of an apparatus for measuring a surface potential of a toner carrier.

FIG. 3 is a schematic plan view showing shapes and dimensions of measurement units used in Examples and Comparative Examples.

FIG. 4 is a schematic sectional view showing an example of the image forming apparatus (developing apparatus) of the present invention.

FIG. 5 is a schematic view showing a rotational resistance measuring instrument used in Examples and Comparative Examples.

FIG. 6 is a graph showing an example of a surface charge decay curve of a toner carrier.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Developing roller 2 Shaft 3 Semiconductive layer 3a Resin coating layer 4 Toner application roller 5 Photosensitive drum (image forming body) 6 Toner (non-magnetic one-component developer) 7 Layering blade 8 Transfer unit 9 Cleaning unit 10 Cleaning blade 11 Chuck 12 Corotron discharger (Corona discharger) 13 Surface potentiometer

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Takahiro Kawagoe 1302-57, Aobadai, Tokorozawa-shi, Saitama (72) Inventor Takashi Kitamura 5-36-7 Ominami, Musashimurayama-shi, Tokyo F-term (reference) 2H077 AD06 EA14 EA15 EA16 FA13 FA22 FA25 FA26 FA29 GA12

Claims (5)

[Claims] 1. A semiconductive layer is formed on the outer periphery of a good conductive shaft, and a nonmagnetic one-component developer is carried on the surface to form a thin layer of the developer. 8 kV is applied to a corona discharger arranged at a distance of 1 mm from the surface of a toner carrier that forms a visible image on the image forming body by supplying the developer to the surface of the image forming body in contact with or in proximity to the surface. From the time of charge application when the surface is charged by applying a voltage of.
The absolute value of the surface potential decay rate until after 2 seconds is 0.1 [V / s]
ec] or more. 2. The electric resistance value when 100 V is applied is 10 ⁴ to
2. The toner carrier according to claim 1, wherein the resistance is 10 ¹⁰ Ω. 3. The toner carrier according to claim 1, wherein a semiconductive or insulating resin coating layer is formed on the surface of the semiconductive layer. 4. An image comprising a toner carrier which carries a non-magnetic one-component developer on its surface to form a thin layer of the developer, and which carries the developer and supplies it to the surface of the image forming body. An image forming apparatus, wherein the toner carrier according to claim 1 is used as a toner carrier in a forming apparatus. 5. The image forming member is a latent image holding member holding an electrostatic latent image on the surface, and the non-magnetic one-component developer held on the toner holding member surface is held on the latent image holding member surface. The image forming apparatus according to claim 4, wherein the image forming apparatus is configured to visualize the electrostatic latent image by attaching the image to the electrostatic latent image.