JPH09244290A - Contact development method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent fusion and to enable the formation of images having good image quality free from image defects by using toners added with inorg. particulates of a large grain size having a function to prevent the fusion to a rigid member as the toners to be combined with the rigid member. SOLUTION: A developing device 1 has a developing roller 11 and the rigid member 12 as a regulating means for thin layer formation which is planar and one surface of which is brought into pressurized contact with the surface of this developing roller 11, a toner replenishing roller 13 of which the surface is similarly brought into pressurized contact with the surface of the developing roller 11 and an agitating means 14 which is arranged behind this toner replenishing roller 13. In such a case, the toners added with the inorg. particulates of 0.1 to 1.0μm in the grain size based on the volume within a range where the pts.wt. (x) of addition per 100 pts.wt. toners satisfies the equation 0.1<=x<1.5 is used. While the inorg. particulates are not particularly limited, the particulates of magnetite are adequately used.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a contact using a non-magnetic one-component toner as a developer, which is used in an image forming apparatus such as an electrostatic copying machine, a laser printer apparatus, a plain paper facsimile apparatus or the like. The present invention relates to a developing method.

[0002]

2. Description of the Related Art In the contact developing method, a thin layer of the non-magnetic one-component toner is formed on the surface of a developing roller, at least the surface of which is made of flexible urethane rubber or the like. Is contacted with the electrostatic latent image formed on the surface of the photoconductor to electrostatically adhere the toner in the thin layer to the surface of the photoconductor in accordance with the distribution of charges in the electrostatic latent image, Is a method for developing an electrostatic latent image into a toner image.

In the above contact developing method, the developing roller has conventionally been used as a regulating means for regulating the amount of toner held on the surface of the developing roller to form a thin layer of toner on the surface of the developing roller. An elastic member such as rubber that has been pressure-welded is used. However, since the elastic member is pressed against the developing roller due to its elasticity, it is an important factor in determining the layer thickness of the thin layer formed on the surface of the developing roller and the uniformity of the layer thickness. There is a problem that the pressure contact force of the elastic member to the developing roller is directly affected by the physical properties such as the elastic modulus and hardness of the elastic member. And
(a) Due to non-uniformity of materials, manufacturing error, etc., the above physical properties vary within the same elastic member, and the pressure contact force of the elastic member also varies accordingly. The thickness of the thin layer becomes uneven in the width direction of the developing roller, and (b) the above physical properties change according to changes in environmental conditions such as atmospheric temperature and humidity, and the pressure contact force also changes accordingly. The physical properties of the thin layer formed on the surface of the developing roller change over time due to changes in environmental conditions or (c) deterioration of the elastic member due to long-term use. However, the pressing force also changes over time, and the layer thickness of the thin layer formed on the surface of the developing roller may fluctuate over time, which may affect the quality of the formed image. there were. In addition, the pressure contact force may vary from product to product due to non-uniformity of materials, manufacturing errors, and the like, which may cause a problem that the yield of elastic members is reduced.

Therefore, recently, a plate-shaped rigid member such as a plate glass having a smooth and smooth surface is used as the regulating means.
It has been proposed to use such a rigid member as a regulating means in a state where one smooth surface of the rigid member is in pressure contact with the surface of the developing roller (see, for example, JP-A-7-36277). The rigid member is pressed against the developing roller by another member such as a spring, the pressing force at that time is not directly related to the physical properties of the rigid member, and has higher durability than the elastic member. Since it can withstand use for a longer period of time, it does not have the problem of the elastic member described above.

[0005]

However, in the contact developing method using the plate-shaped rigid member as the regulating means as described above, the stress applied to each toner from the rigid member is larger than that in the elastic member. It has been clarified by the present inventors that the toner is likely to be fused to the rigid member because it becomes higher and the fusion affects the image quality of the formed image.

That is, when toner fusion occurs, the thin layer of toner becomes thinner in that portion than in other portions.
If the thin layer on the developing roller becomes non-uniform and the image density becomes uneven, or if fusion progresses further, a thin layer of toner is not formed at that portion, so the traces are white on the formed image. May remain as streaks (streaks along the rotation direction of the developing roller and the photoconductor, and the sheet conveyance direction).

In order to prevent the fusion of the toner to the rigid member, the inventors have increased the molecular weight of the fixing resin constituting the toner to improve the thermal or mechanical durability of the toner. Or a fluidizing agent added as an external additive to the toner (for example, a volume-based average particle size of 0.01 μm).
It was investigated to increase the fluidity of the toner by increasing the addition amount of (fine particles of about m).

In the former case, however, there arises a problem that the fixing property of the toner on paper or the like becomes insufficient, and particularly in the case of an organic photoconductor, the surface of the photosensitive layer is scraped by the toner, so-called drum. It has been found that shaving tends to occur, and when the shaving amount increases, a margin portion of a formed image may be stained by adhesion of toner, so-called image fogging may occur.

In the latter case, the surplus fluidizing agent is
For example, it has become clear that there is a possibility that problems such as adhesion to a charger or the like used for charging and discharging of the surface of the photoconductor, or particularly adhesion to the surface of the organic photoconductor, so-called filming, may occur. It was An object of the present invention is to use a restricting means composed of a plate-shaped rigid member for forming a thin layer of toner on the surface of a developing roller, and without causing various problems as described above. It is an object of the present invention to provide a contact developing method capable of surely preventing the toner from being fused to the surface and forming an image with good image quality without image defects.

[0010]

In order to solve the above problems, the present inventors have added to the toner, as an external additive, inorganic fine particles having a large particle diameter having a polishing action, and the inorganic fine particles have a polishing action. In consideration of preventing fusion of the toner to the rigid member, the present invention has been completed as a result of studying the preferable particle size range of the inorganic fine particles and the range of the addition amount.

That is, according to the contact developing method of the present invention, a thin layer of toner formed on the surface of the developing roller is brought into contact with the electrostatic latent image formed on the surface of the photosensitive member, and the electrostatic latent image is transferred to the toner. When the image is visualized, the amount of toner retained on the surface of the developing roller is regulated, and as a regulating means for forming a thin layer of toner on the surface of the developing roller, it is plate-shaped and one surface thereof is While using a rigid member pressed against the surface of the developing roller, inorganic fine particles having a volume-based average particle diameter of 0.1 to 1.0 μm are used as the toner.
It is characterized in that the added amount x to 100 parts by weight of the toner is added in a range satisfying the formula (i): 0.1 ≦ x <1.5 (i).

In the contact developing method of the present invention,
The reason why the average particle size of the inorganic fine particles and the addition weight part are limited within the above ranges is as follows. That is, when the volume-based average particle diameter of the inorganic fine particles is less than 0.1 μm, or when the addition weight part of external addition of the inorganic fine particles to 100 parts by weight of the toner is less than 0.1 part by weight, The polishing action by the inorganic fine particles becomes insufficient, which causes a problem that the fusion of the toner to the rigid member cannot be prevented.

On the other hand, when the volume-based average particle diameter of the above-mentioned inorganic fine particles exceeds 1.0 μm, or when the addition weight part of external addition of the above-mentioned inorganic fine particles to 100 parts by weight of the toner is 1.5 parts by weight or more. In some cases, especially in the case of combination with an organic photoreceptor, the surface of the photosensitive layer is scraped by inorganic fine particles, so-called drum scraping occurs, and when the scraped amount becomes large, fogging occurs in a formed image. Cause

When the volume-based average particle diameter of the inorganic fine particles exceeds 1.0 μm, the thin layer of toner formed on the surface of the developing roller is disturbed, thereby disturbing the formed image. Problems also arise.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below. FIG. 1 shows an example of a developing device for carrying out the contact developing method of the present invention. The developing device 1 includes a developing roller 11 and a rigid member 1 in the form of a plate, one surface of which is pressed against the surface of the developing roller 11 as a regulation means for forming a thin layer.
2, a toner replenishing roller 13 whose surface is also in pressure contact with the surface of the developing roller 11, and a stirring means 14 arranged behind the toner replenishing roller 13, and the above-mentioned respective parts in the apparatus main body 10 And is arranged so that the surface of the developing roller 11 is brought into pressure contact with the surface of the photoconductor 2 of the image forming apparatus.

Of the above, as the developing roller 11, a roller having at least its surface formed of a flexible urethane rubber or the like is preferably used as in the conventional case. The developing roller 11 having such a flexible surface not only has a risk of damaging the surface of the photoconductor 2, but also makes it easier for the toner to pass through between the developing roller 11 and the rigid member, thereby forming the above-described image density unevenness on the formed image. It also has an effect of preventing image defects such as vertical stripes from occurring to some extent.

As the rigid member 12 abutting on the developing roller 11, plate bodies made of various rigid materials can be used. Particularly, as described above, plate glass is used as the developing roller 1.
It is preferably used in terms of the smoothness of the surface which is the pressure contact surface against No. 1 or the rigidity of the whole. The rigid member 12
Is a pressure contact means (not shown) such as a spring,
It is pressed against the surface of the developing roller 11 with a predetermined pressing force. Further, the developing roller 11 is pressed against the surface of the photoconductor 2 with a predetermined pressing force by a pressing means (also a spring or the like) not shown.

Contact development of an electrostatic latent image using the developing device 1 is carried out by the following procedure. That is, first, the photoconductor 2, the developing roller 11, the toner replenishing roller 13, and the stirring means 14 are rotated at predetermined rotational speeds in the directions of the arrows shown in the drawing. Then, stirring means 1
The toner (not shown) agitated at 4 and supplied to the surface of the developing roller 11 by the toner replenishing roller 13 is charged and held by friction with the developing roller 11,
In addition, the amount of the toner held is regulated by the rigid member 12 which is the regulation means, and the toner is attached to the surface of the developing roller 11 by the action of the image force of the elastic member 12, and the toner is adhered to the surface of the developing roller 11. A thin layer is formed.

On the other hand, an electrostatic latent image corresponding to the formed image is formed on the surface of the photoconductor 2 through the steps of charging and exposing. Then, the electrostatic latent image on the surface of the photoconductor 2 is brought into contact with the thin layer of toner on the surface of the developing roller 11, and the toner in the thin layer is transferred to the photoconductor according to the distribution of the charges in the electrostatic latent image. Electrostatically adheres to the surface of No. 2 and thereby the electrostatic latent image is visualized as a toner image, completing one step of contact development.

In the contact developing method, a photosensitive member and a toner which are charged to have the same polarity are combined, and the toner is selectively adhered to a portion of the surface of the uniformly charged photosensitive member where the potential is lowered by exposure. By combining the so-called negative-positive reversal development, which forms a toner image, and a photoreceptor and toner that are charged with opposite polarities, the potential on the surface of the photoreceptor uniformly charged did not decrease due to exposure. There is so-called positive-positive development in which toner is selectively adhered to a portion to form a toner image, and the contact development method of the present invention is
It is applicable to any of these methods.

The toner used in the above contact developing method is
In the present invention, as described above, as the external additive, the inorganic fine particles having a volume-based average particle diameter of 0.1 to 1.0 μm are added, and the addition weight part x with respect to 100 parts by weight of the toner is represented by the formula:
(i): 0.1 ≦ x <1.5 It has to be added within a range satisfying (i). The reason is as described above.

The above-mentioned inorganic fine particles are not limited to these, but for example, magnetite [iron (III) oxide iron (I
I)], fine particles of aluminum oxide, silicon oxide, titanium oxide, zinc oxide and the like. Among them, magnetite fine particles are preferably used because they have excellent abrasive effect on fused toner and little abrasion of the drum. To be done.
The magnetite fine particles are mainly supplied in a spherical or cubic shape, and in the present invention, any of the above shapes may be used alone, or a spherical shape and a cubic shape may be mixed. May be used.

When the above magnetite fine particles are used as the inorganic fine particles, the volume-based average particle diameter of the magnetite fine particles is particularly 0 within the above range in consideration of the polishing effect of the fused toner and prevention of drum abrasion. .3 ~
It is preferably about 0.7 μm. Further, the addition amount by weight of the magnetite fine particles to 100 parts by weight of the toner is preferably 0.3 part by weight or more even within the above range in consideration of compatibility of both effects described above.
More preferably, it is about 5 to 0.7 parts by weight.

In order to improve the fluidity and charging characteristics of the toner, the toner has a particle size that is smaller than that of the above-mentioned inorganic fine particles as an abrasive by about one digit, that is, the volume-based primary average particle size is 10 nm. About the level of particles (fluidizing agent)
It may be added as an external additive as in the prior art. Examples of the fluidizing agent include fine powders of metal oxides such as aluminum oxide, silicon oxide, titanium oxide, and zinc oxide,
Alternatively, various conventionally known fine particles such as fluororesin fine particles can be used, and particularly, a silica-based surface treatment agent containing hydrophobic or hydrophilic silica fine particles, for example, ultrafine particle anhydrous silica or colloidal silica is preferably used. .

The addition amount of the fluidizing agent is not particularly limited and may be the same level as in the conventional case. Specifically, it is preferable to add the fluidizing agent in a total amount of about 0.1 to 3.0 parts by weight to 100 parts by weight of the toner, but in some cases, the fluidizing agent may be added in an amount of It may be out of this range. As a toner to which the above-mentioned abrasive or fluidizing agent is added as an external additive, a coloring resin and other components are added to a fixing resin in the same manner as in the conventional case, and the mixture is homogeneously preliminarily mixed by a dry blender, a Henschel mixer, a ball mill or the like. The mixture thus obtained is uniformly melted and kneaded by using a kneading device such as a Banbury mixer, a roll, a uniaxial or biaxial kneading extruder, and the obtained kneaded product is cooled and pulverized. A toner produced by a so-called pulverization method, which is classified as necessary, is preferably used, and a toner having a nearly spherical shape produced by a production method using a suspension polymerization method, a dispersion polymerization method, or the like is also used. it can. However, since the toner having a shape close to a sphere easily slips between the rigid member which is the regulation means and the developing roller, the entire thin layer formed on the developing roller becomes thicker than necessary, or partially. As a result of becoming thick and non-uniform, there is a possibility that so-called image fogging occurs, that is, the margin portion of the formed image is stained by the adhesion of toner. Therefore, when using a toner manufactured by a manufacturing method utilizing a suspension polymerization method, a dispersion polymerization method, or the like, it is preferable to use a toner which is modified by some means in the subsequent step or in the manufacturing process.

The physical properties of the toner are not particularly limited, but the center particle diameter of the toner is preferably about 6.0 to 12.0 μm, and 10 μm or less particularly for the purpose of improving the quality of the formed image. However, a normal toner having a particle size of more than 10 μm may be used. Further, in a system using plate glass as the rigid member, it is preferable that the volume resistance value of the toner is 10 ⁸ Ω · cm or more in consideration of charging characteristics and the like.

However, the physical properties such as the central particle diameter and the volume resistance value of the toner can be appropriately changed according to the system used. As the fixing resin constituting the toner manufactured by the pulverization method, for example, polystyrene,
Chloropolystyrene, poly-α-methylstyrene, styrene-chlorostyrene copolymer, styrene-propylene copolymer, styrene-butadiene copolymer, styrene-
Vinyl chloride copolymer, styrene-vinyl acetate copolymer,
Styrene-maleic acid copolymer, styrene-acrylate copolymer (styrene-methyl acrylate copolymer, styrene-ethyl acrylate copolymer, styrene-
Butyl acrylate copolymer, styrene-octyl acrylate copolymer, styrene-phenyl acrylate copolymer, etc.), styrene-methacrylic acid ester copolymer (styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate) Copolymers, styrene-butyl methacrylate copolymers, styrene-phenyl methacrylate copolymers, etc.), styrene-α-chloromethyl acrylate copolymers, styrene-acrylonitrile-acrylic acid ester copolymers, etc. Resin (styrene or homopolymer containing styrene substitution product), polyvinyl chloride, low molecular weight polyethylene, low molecular weight polypropylene, ethylene-ethyl acrylate copolymer, polyvinyl butyral, ethylene-vinyl acetate copolymer, Rosin-modified maleic acid resin, Lumpur resins, epoxy resins, polyester resins, ionomer resins, polyurethane resins, silicone resins, ketone resins, xylene resins, polyamide resins, etc. These are used alone or in two or more.

As the colorant, various conventionally known dyes, pigments and the like can be used, but in the case of a black toner, carbon black is mainly used. As the carbon black, various conventionally known carbon blacks such as channel black, roller black, disc black, gas furnace black, oil furnace black, thermal black and acetylene black can be used.

The amount of carbon black added to the fixing resin is not particularly limited, but since the carbon black itself has conductivity, it serves as a means for controlling the electrical characteristics of the toner, which is related to the charging of the toner. Is also playing. Therefore, it is preferable to set a preferable range of the addition amount in accordance with the intended performance of the toner (particularly the volume resistance value of the toner described above). Although not limited to this, the addition amount of carbon black is preferably about 1 to 9 parts by weight with respect to 100 parts by weight of the fixing resin from the viewpoint of the charging property of the developer and the like.

Other components added to the fixing resin together with the colorant include, for example, a charge control agent, a release agent (anti-offset agent), and various stabilizers.
As the charge control agent, one of two types of charge control agents for controlling positive charge and controlling negative charge is used as the charge control agent. As the charge control agent for controlling the positive charge, organic compounds having a basic nitrogen atom such as basic dyes, aminopyrine, pyrimidine compounds, polynuclear polyamino compounds, aminosilanes and the like, and surface-treated with each of the above compounds are used. Examples include fillers.

As the charge control agent for controlling the negative charge,
For example, a compound having a carboxyl group such as a metal chelate of alkylsalicylic acid, a metal complex salt dye, a fatty acid soap,
In addition to resin acid soaps, metal salts of naphthenic acid, etc., oil-soluble dyes such as nigrosine base (C.I.5045), oil black (C.I.26150), Bontron S, and Spiron Black, or styrene- Examples thereof include charge control resins (CCR) such as styrene sulfonic acid copolymer.

The charge control agent is added in an amount of 0.1 to 10 parts by weight, preferably 0.5 to 5 parts by weight, based on 100 parts by weight of the fixing resin. Examples of the release agent (anti-offset agent) include aliphatic hydrocarbons, aliphatic metal salts,
Examples include higher fatty acids, fatty acid esters or partially saponified products thereof, silicone oil, various waxes and the like. Among them, aliphatic hydrocarbons having a weight average molecular weight of about 1,000 to 10,000 are preferred. Specifically, one or a combination of two or more of low-molecular-weight polypropylene, low-molecular-weight polyethylene, paraffin wax, and a low-molecular-weight olefin polymer composed of olefin units having 4 or more carbon atoms is suitable.

The release agent is added in an amount of 0.1 to 10 parts by weight, preferably 0.5 to 8 parts by weight, based on 100 parts by weight of the fixing resin.

[0034]

The present invention will be described below based on Reference Examples, Examples and Comparative Examples. Reference Example <Production of Toner> The following components are mixed using a Henschel mixer, melted and kneaded in a twin-screw kneading extruder, cooled, and then coarsely pulverized by a feather mill, and the coarsely pulverized product is jetted. In a state of being mixed with an air flow, the particles were collided with a collision plate and finely pulverized, and the obtained finely pulverized product was classified by an air classifier to produce a toner having a volume-based average particle diameter of 10.1 μm.

[0035] To 100 parts by weight of the toners prepared in Examples 1 to 5 and Comparative Examples 1 and 2 and 0.3 parts by weight of silica fine powder having a volume-based primary average particle diameter of 16 nm as a fluidizing agent were polished. Magnetizing fine particles having a volume-based average particle diameter of 0.3 μm as an agent were added to produce a positive charging type non-magnetic one-component type developer. The added weight parts of the magnetite fine particles with respect to 100 parts by weight of the toner were 0.1 parts by weight (Example 1), 0.3 parts by weight (Example 2), 0.5 parts by weight (Example 3), and 0. 7 parts by weight (Example 4), 1.0 parts by weight (Example 5), and 1.5 parts by weight (Comparative Example 2). Further, Comparative Example 1 was prepared without adding magnetite fine particles. Actual Machine Test The developer manufactured in each of the above Examples and Comparative Examples is combined with a developing roller 11 made of urethane rubber and a rigid member 12 made of plate glass to have a developing device 1 having a structure shown in FIG.
The developing device 1 is used in a non-magnetic one-component contact developing type plain paper facsimile device [TC-720 manufactured by Mita Kogyo Co., Ltd.] in combination with a positively charging type organic photoconductor 2 to actually produce a black and white image. An image was continuously formed on 45,000 sheets, and the number of image formations in which vertical stripes were generated in the formed image was recorded. The results are shown in Table 1.

[0036]

[Table 1]

From Table 1, when the developer of Comparative Example 1 to which magnetite fine particles were not added was used, vertical streaks were generated in the formed image at a relatively early stage when the number of image formed was 1,000. Further, when the inside of the apparatus was observed at this time, it was observed that a large amount of toner was fused to the rigid member. On the other hand, when using the developers of Examples 1 to 5 and Comparative Example 2 to which magnetite fine particles were added,
When the number of images formed is less than 18,000, no warp is generated, and particularly when the developers of Examples 4 and 5 and Comparative Example 2 in which the amount of magnetite fine particles added exceeds 0.7 parts by weight, 45,000. No vertical streaking occurred until the end of continuous image formation.

When the surface of the photoconductor was observed after completion of the continuous image formation of 45,000 sheets, it was found that the photoconductor surface was greatly scraped, especially when the developers of Example 5 and Comparative Example 2 were used. all right. Then, when the developer of Example 5 and the developer of Comparative Example 2 were used, the abrasion amount of the photoconductor (the reduction amount of the thickness of the photosensitive layer) was measured. In Example 5, the abrasion amount was 0.8 μm at maximum. In practice, the amount of abrasion was within the allowable range (within 1 μm), but in Comparative Example 2, the maximum amount of abrasion was 1.3 μm, which exceeds the allowable range of abrasion. I understood. Examples 6 to 10 and Comparative Example 3 To 100 parts by weight of the toner prepared in Reference Example, 0.3 parts by weight of silica fine powder having a volume-based primary average particle diameter of 16 nm as a fluidizing agent was used as an abrasive. And a magnetite fine particle having a volume-based average particle diameter of 0.7 μm were added to produce a positive charging type non-magnetic one-component developer. The added weight parts of the magnetite fine particles to 100 weight parts of the toner were 0.1 parts by weight (Example 6), 0.3 parts by weight (Example 7), 0.5 parts by weight (Example 8), and 0. 7 parts by weight (Example 9), 1.0 parts by weight (Example 10), and 1.5 parts by weight (Comparative Example 3).

Then, the above-mentioned actual machine test was conducted for the developers produced in the above-mentioned respective Examples and Comparative Examples, and the characteristics thereof were evaluated. Table 2 shows the results.

[0040]

[Table 2]

From Table 2, Examples 6 to 10 and Comparative Example 3
When using the developer of 1,900
When the number of sheets is less than 0, no warp is generated, and particularly when the developers of Examples 9 and 10 and Comparative Example 3 in which the amount of magnetite fine particles added exceeds 0.7 parts by weight, 45,000.
It was found that no vertical streak occurred until the end of continuous image formation.

When the surface of the photoconductor was observed after completion of the continuous image formation of 45,000 sheets, it was found that the photoconductor surface was greatly scraped, especially when the developers of Example 10 and Comparative Example 3 were used. all right. Therefore, the tenth embodiment
When the developer of Comparative Example 3 and the developer of Comparative Example 3 were used, the amount of abrasion of the photoconductor (the amount of reduction in the thickness of the photosensitive layer) was measured.
0 was the maximum scraping amount of 0.9 μm, which was within the allowable range of the scraping amount (within 1 μm), while Comparative Example 3 had the maximum scraping amount of 1.5 μm, and the allowable range of the scraping amount was It turns out that it has exceeded. Examples 11 to 13 To 100 parts by weight of the toner prepared in Reference Example, 0.3 parts by weight of silica fine powder having a volume-based primary average particle diameter of 16 nm as a fluidizing agent, and a volume-based abrasive as an abrasive And aluminum oxide fine particles having an average particle diameter of 0.5 μm were added to produce a positive charging type non-magnetic one-component type developer. The amount of the aluminum oxide fine particles added to 100 parts by weight of the toner was 0.1 parts by weight (Example 1).
1), 0.5 parts by weight (Example 12), and 1.0 parts by weight (Example 13).

Then, the above-mentioned actual machine test was conducted on the developers produced in the above-mentioned respective examples, and the characteristics thereof were evaluated. The results are shown in Table 3.

[0044]

[Table 3]

From Table 3, it was found that when the developers of Examples 11 to 13 were used, no warp was generated when the number of image formed sheets was less than 15500. Examples 14 to 16 To 100 parts by weight of the toner prepared in Reference Example, 0.3 parts by weight of silica fine powder having a volume-based primary average particle diameter of 16 nm as a fluidizing agent and a volume-based polishing agent were used. And a titanium oxide fine particle having an average particle size of 0.4 μm were added to produce a positive charging type non-magnetic one-component type developer.
The amount of titanium oxide fine particles added to 100 parts by weight of the toner was 0.1 parts by weight (Example 14) and 0.1 part by weight.
5 parts by weight (Example 15) and 1.0 parts by weight (Example 16).

Then, the above-mentioned actual machine test was carried out on the developers produced in the above-mentioned respective examples, and their characteristics were evaluated. The results are shown in Table 4.

[0047]

[Table 4]

From Table 4, it was found that when the developers of Examples 14 to 16 were used, no vertical streaks were generated when the number of image formed sheets was less than 14,000.

[0049]

As described above in detail, according to the present invention, the rigid member is used as the regulating means for forming a thin layer of toner on the surface of the developing roller, and the toner is combined with the rigid member. , Which has a function of preventing fusion to the rigid member, is added with the inorganic fine particles having a large particle size, so that the fusion is prevented and an image with good image quality without image defects is obtained. Can be formed.

[Brief description of drawings]

FIG. 1 is a partial cross-sectional view showing a main part of an example of a developing machine for carrying out the contact developing method of the present invention.

[Explanation of symbols]

 11 developing roller 12 rigid member 2 photoconductor

Front Page Continuation (72) Inventor Toshiaki Akiyama 1-2-2 Tamatsukuri, Chuo-ku, Osaka-shi, Mita Industrial Co., Ltd. Industrial Co., Ltd. (72) Inventor Asao Toda 1-2-2 Tamatsukuri, Chuo-ku, Osaka-shi, Osaka Mita Kogyo Co., Ltd.

Claims (1)

[Claims] 1. An electrostatic latent image formed on the surface of a photoconductor is brought into contact with a thin layer of toner formed on the surface of a developing roller to visualize the electrostatic latent image as a toner image. In the contact developing method, the amount of toner retained on the surface of the developing roller is regulated to form a thin layer of toner on the surface of the developing roller.
A rigid member pressed against the surface of the developing roller is used, and the volume-based average particle size of the toner is 0.
An inorganic fine particle having a particle size of 1 to 1.0 μm is added in such a range that the added weight part x with respect to 100 parts by weight of the toner satisfies the formula (i): 0.1 ≦ x <1.5 (i). A contact developing method characterized by the above.