JPH0540403A - Developing device - Google Patents

Abstract

PURPOSE:To provide a developing device capable of eliminating the biased distribution of electrostatic charge quantity in a toner layer formed on a toner carrier farming the toner layer showing uniform and excellent electrostatic charge on the carrier and obtaining a stable high-quality image. CONSTITUTION:At least the surface of the toner carrier 5 consists of a dielectric substance and at least the surface of a toner regulation member 6 consists of the dielectric substance which is identical to the dielectric substance constituting the surface of the carrier 5. Besides, the toner carrier 5 carrying toner on the surface by a replenishment roller 4 is supplied and a uniform thin layer is formed by the regulation member 6. Then, an electrostatic latent image is developed on a holding body which holds it.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing device for electrophotography, and more particularly to a developing device using a one-component toner.

[0002]

2. Description of the Related Art In an image forming apparatus such as an electronic copying machine, a printer or a facsimile, which forms an electrostatic latent image on an electrostatic latent image holder and visualizes it with a developer to obtain a recorded image, a powdery powder is used. A dry developing device using a developer is widely adopted. The powdery developer includes a two-component developer having a toner and a carrier, and a one-component developer containing no carrier, and the two-component developing method using the former two-component developer is Although a relatively stable and good image can be obtained, it has a drawback that carrier deterioration and variation in the mixing ratio of toner and carrier are likely to occur, maintenance of the device is complicated, and the size of the entire device tends to be large. There is.

From such a viewpoint, a one-component developing system using a one-component developer which does not have the above-mentioned drawbacks has been attracting attention. The one-component developer is classified into a toner consisting only of toner, a toner in which an auxiliary agent is externally added as necessary, and a toner in which the auxiliary agent is mixed. As the toner, there are a magnetic toner in which magnetic powder is kneaded into each toner particle itself and a non-magnetic toner containing no magnetic powder. Here, since the magnetic substance is generally opaque, when a color image including full color and multi-color is formed with magnetic toner, the developed visible image becomes unclear and a vivid color image cannot be obtained. Therefore, particularly for color development, it is desirable to adopt the one-component development method using non-magnetic toner. By the way, in a developing device adopting a one-component developing method, a one-component developer is carried on a developer carrier and conveyed, and in a developing area where the developer carrier and the electrostatic latent image carrier face each other. The electrostatic latent image formed on the latent image carrier is visualized with a developer, but a sufficient amount of sufficiently charged toner to form a high-quality visible image with a predetermined density is applied to the developing area. It is necessary to convey the latent image to a visible image with such toner.

The amount of toner formed on the toner carrier varies depending on its structure. For example, a carrier that conveys a large amount of toner at a time to obtain a predetermined density may be used, or a shortage of the conveyed amount may result in a latent image carrier. Some are compensated by changing the relative speed ratio with. In any case, in order to obtain a stable image, at least 0.3 mg / cm on the carrier.
^Two or more toner layers are formed. In this case, the toner layer is not formed in a single layer state, but the toner particles are formed in several layers. Therefore, a difference in charge naturally occurs between the toner located near the surface of the carrier and the toner separated therefrom. That is, a charging distribution in which the charging layer is high below the toner layer (immediately above the carrier) and low above the toner layer occurs. This becomes more noticeable as the toner conveyance amount increases, and reverse polarity toner is likely to be generated in the uppermost layer of the toner layer, which causes a background stain.

[0005]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned drawbacks and eliminates the uneven charge amount distribution in the toner layer formed on the toner carrier, and shows a uniform and good toner layer. It is an object of the present invention to provide a developing device in which a stable high-quality image is obtained by forming an image on a carrier.

[0006]

In order to achieve the above-mentioned object, that is, in order to make the charge distribution in the toner layer uniform, the present inventors have paid attention to the regulating member and as a result, It has been found that it is effective to use at least the same dielectric as the dielectric constituting the surface of the carrier.

That is, according to the present invention, the toner is supplied to the toner carrying member carrying the toner on the surface by the replenishing roller, and a uniform thin layer is formed by the regulating member.
In a developing device that develops on a holding body that holds an electrostatic latent image, at least the surface of the toner carrying body is made of a dielectric material, and at least the surface of the regulating member is a dielectric body that constitutes the surface of the carrying body. A developing device is provided which is made of the same dielectric material. Further, according to the present invention,
In a developing device in which toner is supplied to a toner carrier having toner on its surface by a replenishing roller, a uniform thin layer is formed by a regulating member, and development is performed on the carrier holding an electrostatic latent image, the toner carrier At least the surfaces of both the toner control member and the toner control member are made of the same dielectric material, and an electric field in the following direction is applied between the toner carrier and the toner control member. To be done.

The developing device of the present invention will be described below with reference to FIG. In FIG. 1, 1 is a container, 2 is a toner, 3 is an agitator, 4 is a replenishing roller, 5 is a toner carrier, 6 is a toner regulating member, and 7 is an electrostatic latent image holder (photoconductor).

In FIG. 1, a toner container 1 contains a non-magnetic one-component toner 2. The toner 2 is carried by the agitator 3 on the surface of the toner carrier 5 which is transported to the toner storage portion formed by the replenishing roller 4 and the toner carrier 5. Further, the toner regulating member 6 forms a uniform thin layer and is triboelectrically charged to a predetermined polarity. The thin toner layer is a holder (photoreceptor) that holds the electrostatic latent image.
7 and the toner carrier 5 are brought into contact with the developing area, where the toner electrostatically moves from the toner carrier to the holder 7, and the latent image is visualized.

In the above process, the toner layer is uniformly formed by the regulating member 6, but the toner particles are not a single layer but the toner particles are superposed in several layers. Therefore, the lower layer toner which is close to the toner carrying member shows a good charge, but the upper layer toner which is not so has a low charge. This tendency becomes more remarkable as a sufficient amount of toner layer is formed, and the amount of reverse polarity toner also increases, which causes scumming and toner scattering. According to the first aspect of the present invention, in order to improve the bias of the charge distribution in the toner layer and make the charge distribution uniform, at least the surfaces of both the toner carrier and the toner regulating member are made of the same dielectric as described above. The developing device is configured to eliminate scumming and toner scattering. In this case, of course, very good frictional charging is performed between the toner regulating member and the toner.
That is, a high charge amount is given to the toner, and a high-quality image that does not cause scumming and toner scattering can be obtained. In this case, between the carrier and the regulating member, the electric field in the direction from the regulating member to the carrier when positively charged toner is used and from the carrier to the regulating member when negatively charged toner is used. The above-mentioned effect is further improved by adopting a configuration for applying the voltage.
The invention of claim 2 embodies such a configuration (see FIG. 2). That is, the toner receives an electric field from the regulating member to the supporting body between the supporting body and the regulating member. Therefore, the toner is prevented from sticking to the regulating member. Further, when the toner having the opposite polarity is present in the toner layer, the toner is not adhered to the regulating member by the electric field and does not flow out to the developing area, and therefore the background stain can be prevented more effectively. The opposite polarity toner attached to the regulating member is charged to a desired charging polarity by contact with the regulating member, and again adheres to the carrier and is developed by the electric field. Therefore, it does not stick to the regulating member. However, it takes time to charge the toner, which has a low polarity but is once charged to the opposite polarity, to the desired polarity. That is, the rise of charging is slightly slow. Therefore, as a restriction member, FIG.
It is preferable to use a rotating body as shown in FIG. As shown in the figure, the cleaning member 8 is installed on the rotating member regulating member, whereby the excess toner and the opposite polarity toner carried to the regulating member are scraped off and returned to the toner tank. Further, by using an alternating electric field as the electric field applied between the carrier and the regulating member, the toner vibrates between the carrier and the regulating member, and this effect is brought out more, and at the same time, the charge amount and the charge rising property are improved. To do.

In order to further bring out the effect of the present invention, it is preferable to use a toner having good fluidity.
When a toner having good fluidity is used, when a thin layer is formed on the regulation member, the mobility of the toner particles in the toner layer is good, the contact between the carrier and the regulation member is increased, and it becomes possible to charge the toner more uniformly. .. The fluidity of the toner is preferably 30% or less in terms of aggregation degree (the measuring method will be described later).
It is good to say

Further, in the present invention, the toner carrying member is not limited to a roller-shaped member, but may be, for example, a belt-shaped member. The electrostatic latent image holding member is not limited to the photoconductor, and may be any member that can hold an electrostatic latent image.

FIG. 4 shows an example of the toner carrier used in the present invention. In the figure, 21 is a core metal, and 22 is a dielectric layer. A conventionally known metal or the like is used for the cored bar 21. Dielectric layer 2
Although a general resin or rubber can be used for 2, a material having a volume resistance of 10 ⁸ Ω · cm or more is preferable in order to obtain stable and sufficient chargeability with the toner and the toner amount.

For example, as the resin, alkyd resin,
Chlorinated polyether, chlorinated polyethylene, epoxy resin, fluorine resin, phenol resin, polyamide, polycarbonate, polyethylene, methacrylic resin, polypropylene, polystyrene resin, polyurethane, polyvinyl chloride, polyvinylidene chloride, silicone resin, etc. or,
Examples of the rubber include butadiene rubber, styrene butadiene rubber, ethylene propylene rubber, polyethylene chloride, epichlorohydrin rubber, nitrile rubber, acrylic rubber, urethane rubber, silicone rubber, and fluorine rubber. From the viewpoint of heat resistance, weather resistance, abrasion resistance, etc., silicone resin, fluorine resin, silicone rubber, and fluorine rubber are preferable.

The structure of the toner carrier in the present invention is not limited to the above-mentioned structure, and it is sufficient that it has the above-mentioned dielectric at least on the surface thereof, and may have a multi-layer structure if necessary. Further, the shape is not limited to the roller shape. FIG. 5 shows an example of the toner regulating member according to the present invention. In the figure, 31 is a support and 32 is a dielectric layer. Support 31
Is installed as needed, and may be omitted if not needed. Materials include metals and plastics,
It is not particularly limited. As the dielectric layer 32, the one used for the surface layer of the toner carrier can be used as it is. The structure is not limited to the above-mentioned structure, and at least the surface may be composed of the same dielectric as the dielectric on the surface of the carrier, and for example, between the dielectric 32 and the support 31 to have elasticity. If necessary, an additional function may be added, such as by providing an elastic layer such as sponge. Further, the shape is not limited to the blade shape as shown in FIG. 5, but may be a roller shape as shown in FIG. 6, for example. For the production of the dielectric layer for both the carrier and the regulating member, an appropriate construction method may be adopted from conventionally known spray coating, dipping, steam vulcanization, extrusion molding, injection molding and the like.

[0016]

EXAMPLES The present invention will be described in detail below with reference to examples and comparative examples. Example 1 (a) Preparation of toner carrier The following dielectric forming components were spray-coated on an Al cored bar roller, and cured and dried at 100 ° C. for 1 hour to form a dielectric layer having a film thickness of 50 μm. Then, a toner carrying member was obtained. The volume resistance of this dielectric was 3 × 10 ¹⁵ Ω · cm. {Dielectric-forming component} Epoxy-modified silicone resin 100 parts by weight (SR2115; manufactured by Toray Dow Corning Silicone) Curing agent 20 parts by weight (SR2115K; manufactured by Toray Dow Corning Silicone) Cellosolve acetate 300 parts by weight Xylene 300 parts by weight (b) Preparation of toner regulating member A dielectric layer having a thickness of 50 μm was prepared on an Al plate under the same conditions with the same dielectric-forming components as described above to obtain a toner regulating member. (C) Toner used A mixture having the following composition was melt-kneaded, cooled, coarsely pulverized using a hammer mill, and then finely pulverized by an air jet type fine pulverizer. The resulting finely pulverized product was classified to have an average particle size of 11 μm. 0.4 part of silica fine powder was added to 100 parts of the particles and mixed to obtain a toner of the present invention. The degree of aggregation of the obtained toner was 22%. {Toner composition} Binder resin Styrene-acrylic polymer 95 parts Release agent Low molecular weight polypropylene 5 parts Colorant carbon black 8 parts Charge control agent Salicylic acid derivative zinc salt 4 parts

The toner aggregation degree was measured by the following method. Use Hosokawa Micron's powder tester to set the accessories on the vibrating table according to the following procedure. (A) Vibro chute (b) Packing (c) Space ring (d) Fluid (3 types) Top>Middle> Bottom (e) Osaver Ever Next, fix with a knob nut and operate the vibrating table. The measurement conditions are as follows. Screen opening (top) 75 μm Screen opening (middle) 45 μm Screen opening (bottom) 25 μm Amplitude scale 1 μm Sampling amount 10 g Vibration time 30 seconds After measurement, calculate the degree of aggregation from the following calculation. The aggregation degree (%) is defined as the sum of the above three calculated values.
That is, aggregation degree (%) = (a) + (b) + (c)

The following evaluations were performed using the above toner carrier, regulating member and toner. (Evaluation of toner charge amount) In the developing device shown in FIG. 1, the toner charge amount of the toner carrier was measured by the blow-off method. (Amount of Toner Adhered) In the developing device of FIG. 1, the amount of toner adhering to the toner carrier was measured by tape transfer. (Evaluation of Image) Using the developing apparatus of FIG. 1, a test chart image was output by an actual machine and the output image was observed.

Example 2 (a) Preparation of toner carrier A core metal roller made of Al was spray-coated with the following dielectric-forming components, and cured and dried under conditions of 100 ° C. for 1 hour to obtain a dielectric having a film thickness of 50 μm. A layer was formed and used as a toner carrier. The volume resistance of this dielectric was 5 × 10 ¹⁴ Ω · cm. {Dielectric-forming component} Fluorocopolymer resin (Lumiflon 200; Asahi Glass) 100 parts by weight Coronate EH 20 parts by weight Toluene 200 parts by weight Xylene 200 parts by weight (b) Preparation of toner regulating member The above-mentioned dielectric forming component on an Al plate. Under the same conditions
A dielectric layer having a thickness of μm was produced and used as a regulating member. (C) Toner used A mixture having the following composition was melt-kneaded, cooled, coarsely pulverized using a hammer mill, and then finely pulverized by an air jet type fine pulverizer. The resulting finely pulverized product was classified to have an average particle size of 12 μm. To 100 parts of the present particles, 0.6 part of fine silica powder was added and mixed to obtain a toner of the present invention. The aggregation degree of this toner was 15%. {Toner composition} Binder resin Styrene-acrylic polymer 95 parts Release agent Low molecular weight polypropylene 5 parts Colorant carbon black 7 parts Charge control agent Nigrosine dye 3 parts

Example 3 A toner carrier and a toner regulating member were produced using this dielectric, except that the following components were added to the dielectric-forming components in Example 1. The volume resistance of this dielectric is 2 x
It was 10 ⁷ Ω · cm. {Additional component} 50 parts by weight of carbon black A toner carrier and a toner regulating member were produced in the same manner as in Example 1 except that the toner carrier and the toner regulating member were used as described above.

Example 4 The amount of silica fine powder added to the toner in Example 1 was adjusted to 0.
The same procedure as in Example 1 was carried out except that the amount was 1 part. At this time, the aggregation degree of the toner was 45%.

Comparative Example 1 The same as Example 2 except that the dielectric layer of the toner regulating member in Example 2 was not formed (that is, only the Al plate).

Comparative Example 2 A developing device of Comparative Example 2 was prepared by using the toner carrier, the toner regulating member and the toner as follows. Toner carrier: Same as Example 3 Toner regulating member: Same as Comparative Example 1 Toner: Same as Example 4

The evaluation results of Examples 1 to 4 and Comparative Examples 1 and 2 are summarized in Table 1.

[0025]

[Table 1]

Example 5 The same as Example 1 except that an electric field was applied between the toner carrying member and the toner regulating member in the direction from the toner regulating member to the toner carrying member. ..

Example 6 The same as Example 2 except that an electric field was applied between the toner carrying member and the regulating member in the direction from the toner regulating member to the toner carrying member.

Example 7 The toner regulating member in Example 1 was produced by coating a core metal roll made of sus with a dielectric in the same manner as in FIG.
The same was applied except that the developing device was used.

Comparative Example 3 The same procedure as in Example 5 was carried out except that the toner regulating member was floated. The following evaluations were performed using the above toner carrier, toner regulating member and toner. The results are shown in Table 2. (Evaluation of Toner Charge Amount) In the developing device shown in FIG. 2, the toner charge amount on the carrier was measured by the blow-off method after one rotation and ten rotations of the support. (Amount of Toner Adhesion) In the developing device of FIG. 2, the amount of toner adhesion on the carrier was measured by tape transfer. (Evaluation of Image) Using the developing device shown in FIG. 2, an image was examined when 10,000 sheets were run on an actual machine. The results are shown in Table 2.

[Table 2] In Comparative Example 3, the image after 10,000 sheets of running had uneven density in some places. At this time, when the toner regulating member was taken out and the surface was observed, the toner was stuck in some places. It was

[0030]

According to the developing device of the present invention, since the toner regulating member formed on at least the surface of the dielectric which is the same as the dielectric constituting the surface of the toner carrier is used, an image free from scumming and toner scattering is formed. Is obtained. Furthermore, this dielectric has a volume resistance of 10 ⁸ Ω · cm or more and a toner cohesion of 3
By setting the content to 0% or less, a high-density image with high density and no unevenness can be obtained. Further, in the developing device according to claim 4, when at least the surfaces of both the toner carrier and the toner regulating member are made of the same dielectric, and a positively chargeable toner is used between the carrier and the regulating member, When a negatively-charged toner is used from the regulating member to the supporting member, an electric field in the direction from the supporting member to the regulating member is applied, so there is no background stain or toner scattering, and No sticking to the regulating member occurs, and even when used for a long time, a uniform and stable toner charge and a thin toner layer are obtained, and a high-quality image can be obtained for a long time.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a typical developing device according to the present invention.

FIG. 2 is an explanatory diagram of another representative developing device according to the present invention.

FIG. 3 is an explanatory diagram of still another developing device according to the present invention.

FIG. 4 is an explanatory diagram of a toner carrier according to the present invention.

FIG. 5 is an explanatory diagram of a toner regulating member according to the present invention.

FIG. 6 is an explanatory diagram of another toner regulating member according to the present invention.

Claims (5)

[Claims] 1. A developing device in which a replenishing roller supplies a toner carrying member carrying a toner on the surface and a regulating member forms a uniform thin layer to develop the electrostatic latent image on a holding member. A developing device, wherein at least the surface of the toner carrier is made of a dielectric material, and at least the surface of the toner regulating member is made of the same dielectric material as the surface of the toner carrier. 2. The volume resistance of the dielectric material constituting at least the surfaces of the toner carrier and the toner regulating member is 10 ⁸ Ω.
The developing device according to claim 1, wherein the developing device has a size of not less than cm. 3. The developing device according to claim 1, wherein the toner has an aggregation degree of 30% or less. 4. A developing device in which toner is supplied to a toner carrier having toner on its surface by a replenishing roller, and a uniform thin layer is formed by a regulating member to develop on a carrier holding an electrostatic latent image. At least the surfaces of both the toner carrier and the toner regulating member are made of the same dielectric, and an electric field in the following direction is applied between the toner carrier and the toner regulating member. Developing device. When positively chargeable toner is used ... From regulating member to toner carrier When negatively chargeable toner is used ... From carrier to toner regulating member 5. The developing device according to claim 4, wherein the toner regulating member is a rotating body having a cleaning member.