JP2001147588A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device where a negative after image of a cycle of a sponge roll, fogging of a background part due to inhomogeneous electrification of toner, deterioration of developing transfer, deterioration of resolution and positive after image of a developing roll cycle can be prevented without any deterioration of image quality or increase of mechanical torque while maintaining a long term stability. SOLUTION: The image forming device includes a developing device provided with a developing container containing one component type developer, an image carrier, a developer carrier and a developer feeding member. When the outer diameter is Dd and surface linear velocity is Vd in the developer carrier, and when the outer diameter is Dr and surface linear velocity is Vr in a developer feeding member, the developing device is constituted so that Dd>=Dr and Vd=Vr.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus, and more particularly, to an image forming apparatus such as an electrophotographic copying machine or an electrophotographic printer which forms an image by visualizing an electrostatic latent image according to an electrophotographic method. The present invention relates to a forming apparatus.

[0002]

2. Description of the Related Art In an image forming apparatus in which an electrostatic latent image is formed on an image carrier in accordance with an electrophotographic method and is visualized with a developer, the size, cost, and reliability of the apparatus are reduced. A developing device using a one-component developer is advantageous. In particular, in order to form a color image, it is advantageous to use a non-magnetic one-component developer because of its high transparency.

Various types of developing devices using a non-magnetic one-component developer are already known.
A typical developing device has a developer carrier that carries a one-component developer on its surface and conveys the developer along a predetermined circulation path including a development area, and a reservoir that stores the one-component developer. Means and a developer supply means for contacting the developer carrier and supplying the one-component developer stored in the developer storage means to the developer carrier. For details of such a developing device, see, for example, JP-A-60-22905.
7 and JP-A-61-42672.

FIG. 1 schematically shows an example of a conventional developing device as described above. The developing device 10 has a casing 13 that defines a developing container (toner hopper) containing a non-magnetic one-component developer composed of only a toner not containing a magnetic substance, that is, a non-magnetic toner 11. , A developing roller 14, a sponge roller 15 for supplying a developer to the developing roller 14, and a thickness regulating blade 16 for regulating the thickness of the developer on the surface of the developing roller 14. An appropriate developing bias voltage can be applied to the developing roller 14 by a bias power supply 21.

The non-magnetic toner 11 contains, for example, silica fine powder as an external additive. The silica fine powder has an effect of controlling the triboelectric charge amount of the toner 11, and can contribute to the improvement of the image density. The developing roller 14 is disposed at the opening of the casing 13 so as to be capable of contacting the photosensitive drum 1 that forms and holds an electrostatic latent image and that holds the electrostatic latent image. Further, the developing roller 14 rotates in the direction in which the developing roller 14 moves in the same direction at a portion facing the photosensitive drum 1, and therefore, the toner 11 carried on the developing roller 14 can be conveyed toward the photosensitive drum 1. .

The sponge roller 15 is made of an elastic sponge material. As shown, the sponge roller 15 elastically contacts the developing roller 14 on the side opposite to the photosensitive drum 1 and rotates in a direction in which the sponge roller 15 moves in the opposite direction at the contact portion with the developing roller 14 (so-called, (Counter rotation), so that the remaining toner remaining on the developing roller 14 (toner not conveyed to the photosensitive drum and therefore not subjected to development) is peeled off, and the developing roller 14 of the new toner 11 in the casing 13 is removed. And supply to the same. Here, the sponge roller 1
The toner 11 newly supplied in step 5 is rubbed between the developing roller 14 and the sponge roller 15 to acquire a charge due to triboelectric charging, adheres to the developing roller 14 by a mirror image force, and is conveyed. Is the developing roller 1
4 and the sponge roller 15 are peeled off by the mechanical force rubbed in the nip. As described above, in the case where the charging and the supply of the new toner are simultaneously performed at the same time as the peeling of the toner remaining after the development, the nip width between the sponge roller 15 and the developing roller 14 is set as wide as possible in order to sufficiently obtain these functions. Preferably, the higher the nip pressure, the more advantageous it is to charge the toner and to strip off the residual toner after development. Further, in the case of a rotating body such as a sponge roller and a developing roller, the same effect as increasing the substantial nip width can be obtained as the linear velocity difference in the counter rotation increases. Therefore, in this type of developing device that has been put into practical use, the hardness of the sponge roller and the nip width with the developing roller are specified (for example, see Japanese Patent Application Laid-Open No.
No. 44023), or the linear speed of the sponge roller is set higher than the linear speed of the developing roller.

The thickness regulating blade 16 is
The developing roller 14 is mounted on the upper portion of the developing roller 14 and is in counter contact with the peripheral surface of the developing roller 14 in a direction opposite to the rotation direction thereof. Accordingly, the toner 11 conveyed toward the photoconductor drum 1 is frictionally charged by the thickness regulating blade 16 during the conveyance, and furthermore, a triboelectric charge is obtained. Further, in order to effectively provide the toner 11 with the triboelectric charge, the developing roller 1 of the thickness regulating blade 16 is used.
In some cases, a member that is charged to a polarity opposite to the charging polarity of the toner 11 is provided on the surface that comes into contact with the toner 4. The toner 11 transported to the developing area on the photosensitive drum 1 is used for developing an electrostatic latent image already formed in that area.

However, in an image forming apparatus using this type of developing device which has been put to practical use, a sponge roller 1 is used.
5 is counter-rotated with respect to the developing roller 14 with a wide nip width and a high nip pressure, and the linear speed of the sponge roller is set to be faster than the linear speed of the developing roller. However, problems such as an increase in toner stress, an increase in mechanical stress on the toner, accelerated deterioration of image quality, an excessive supply of toner to the sponge roller, and an increase in the density of the trailing end of the print have occurred.

[0009] In view of the above-mentioned facts, such a problem is caused by reducing the nip width between the sponge roller 15 and the developing roller 14, reducing the nip pressure, and
The problem can be solved by making the linear speed of the sponge roller 15 close to or equal to the linear speed of the developing roller 14. However, in the case where a solution is taken such that the linear speed of the sponge roller 15 approaches or is equal to the linear speed of the developing roller 14, the following new problem arises.

Since the amount of toner supplied from the sponge roller to the developing roller is insufficient, a negative afterimage occurs in the sponge roller cycle, and the frictional charging of the toner is insufficient. As a result, deterioration of image quality such as deterioration of development transfer and deterioration of resolution occurs, and selective development of toner occurs, so that a positive afterimage occurs in the cycle of the developing roller.

First, a negative afterimage in the sponge roller cycle will be described. As described above, the sponge roller 15
It has a function of supplying toner to the developing roller 14.
In other words, the sponge roller 15 can supply new toner to a portion where the latent image of the developing roller 14 has been developed, where toner is no longer present. After the toner is supplied, the sponge roller 15 transports new toner from a developing container (toner hopper) defined by the casing 13 and is ready to supply the toner again. At this time, in the sponge roller 15, there is a difference between the amount of toner that has been supplied once and the amount of toner that can be supplied to the developing roller 14 where the toner has not been supplied yet. Such a difference in toner amount appears as a density difference in the obtained toner image. This phenomenon is a negative afterimage of the sponge roller cycle here. The negative afterimage of the sponge roller cycle is
In printing, it usually appears at a position corresponding to one rotation of the developing roller and one rotation of the sponge roller. In particular, print afterimages such as solid patches that consume a large amount of toner are conspicuous.

Next, a description will be given of the deterioration of the image quality due to the uneven charge amount of the toner. When the toner is not sufficiently frictionally charged between the sponge roller 15 and the developing roller 14, the toner supplied to the developing roller 15 does not reach the saturation charge amount, and therefore contains low-charged, non-charged or reverse-charged toner. Will be. Then, these inappropriately charged toners hinder development transfer faithful to the latent image,
Adhesion to the background causes fogging of the background, or causes deterioration in resolution, such as the inability to frequently use fine expressions such as one dot. These problems can be solved by the fact that all the supplied toners are saturated.

Next, a description will be given of a positive afterimage in the cycle of the developing roller. Positive afterimage is a phenomenon that, contrary to a negative afterimage, the print density at the place where printing is performed is increased. In this case,
It occurs at the rotation cycle of the developing roller. The mechanism of the generation of a positive afterimage is closely related to the developing mechanism of the non-magnetic one-component developing method. As described above, the toner supplied from the sponge roller 15 adheres to the developing roller 14 with a mirror image due to the charge. Therefore, the adhesive force is proportional to the magnitude of the electric charge, and the larger the electric charge, the more easily it adheres to the developing roller 14, and the smaller the electric charge, the more difficult it is to adhere.
The phenomenon that the toner is selectively supplied to the developing roller 14 depending on the charge amount (selective supply phenomenon) occurs. According to the investigation by the present inventors, it was found that the toner having a high charge amount is a toner having a small particle diameter, and is selectively supplied from the toner having a small particle diameter, and the large toner remains in the toner hopper. . In the case where the toner on the developing roller 14 repeatedly performs an image without toner consumption such as white solid, the toner on the developing roller 14 is activated by the toner selection function every time the toner passes through the nip with the sponge roller 15. The reduction in the particle size of the toner will progress. Then, since the highly charged toner strongly adheres to the developing roller, the potential of the toner layer increases. In the case where the developing roller prints the solid white as described above and performs printing with toner consumption such as a black solid patch, new toner is supplied to a place where the toner is consumed, but this toner is
The toner particle size is larger than where there was no printing,
The charge is small. For this reason, the toner layer in this portion is clearly different from the state of the surrounding toner layer, and a phenomenon (positive afterimage) in which the printing becomes dark occurs. As described above, a positive afterimage occurs due to the selective supply phenomenon of the toner. Positive afterimage is a phenomenon that occurs because the toner has a distribution in chargeability rather than a single toner, and the chargeability mainly depends on the size of the toner particles. Since the selective supply phenomenon is a phenomenon caused by a difference in chargeability, the above-described developing conditions under which charging is not sufficiently performed are conditions under which the selective supply phenomenon is liable to occur remarkably, and therefore, a positive afterimage is also likely to occur. It can be said that.

[0014]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the prior art, and has as its object to degrade image quality due to toner deterioration and increase mechanical torque. Without maintaining the long-term stability, a negative afterimage of the sponge roller cycle caused by an insufficient amount of toner supplied from the sponge roller, and a background fog due to unevenness of the toner charge amount due to insufficient frictional charge of the toner, Worse development transfer, worse resolution,
It is still another object of the present invention to provide an image forming apparatus provided with a developing device capable of preventing a positive afterimage of a developing roller cycle due to toner selective development.

It is another object of the present invention to provide a color image forming apparatus for transmitting a toner such as a color image to visually recognize a color.
As a result, the toner whose image density does not saturate with respect to the attached amount,
That is, it is an object of the present invention to provide a color image forming apparatus using a toner having a fixed melt viscosity in a certain range.
When this toner is used, the melt viscosity at the time of fixing is appropriate, and the smoothness of the image is improved, so that a high-quality glossy image can be formed.

[0016]

According to the present invention, there is provided an image forming apparatus for forming an image by visualizing an electrostatic latent image with a developer, comprising: a developing container containing a one-component developer; ,
An image carrier that forms and holds an electrostatic latent image, and a developer carrier that conveys the developer to a development area on the image carrier, and that is arranged in contact with and opposed to the image carrier; A developer supply member configured to supply a developer in a development container to the developer carrier, the developer supply member being elastically in contact with the developer carrier, and being movably disposed; and the developer supplied from the developer supply member An image forming apparatus including a developing device including a thickness regulating member that regulates the thickness of the developer on the carrier,
The developer carrier is a rotating body having an outer diameter Dd,
The surface linear velocity is Vd, and the developer supply member is a rotating body having an outer diameter Dr, and the surface linear velocity is Vr, with the following relations: Dd ≧ Dr and Vd = Vr Is satisfied, and the one-component developer is 6 to 10
consisting of particles having a volume average particle size of
The ratio of particles having a volume average particle size of not more than μm is 0 to 20.
An image forming apparatus is provided, wherein the ratio of particles having a volume average particle diameter of 12.7 μm or more is 0 to 2% by volume.

In the present invention, the linear velocity of the developer supply member (typically, as described below) is made equal to the linear velocity of the developer carrier (typically, the developing roller),
In addition, by using a developing device in which the outer diameter of the sponge roller is smaller than the outer diameter of the developing roller, the life of the image forming apparatus can be extended, and at the same time, toner having a specific particle size distribution, that is, toner particles Has a volume average particle size of 6-1
0 μm, the proportion of particles having a particle size of 5 μm or less is in the range of 0 to 20% by number, and 12.7 μm.
m, the ratio of particles having a particle size of at least 0 m to 2% by volume can prevent the particle size of the toner from being preferentially supplied between the sponge roller and the developing roller. Even if some diameter selection occurs, a shift in the particle diameter of the toner remaining in the developing container (typically, the toner hopper) can be minimized. Therefore, when the image forming apparatus of the present invention is used, it is possible to prevent the occurrence of a positive afterimage in the cycle of the developing roller as a result.

Further, according to the present invention, there is provided an image forming apparatus for forming an image by visualizing an electrostatic latent image with a developer, comprising: a developing container containing a one-component type developer; An image carrier that forms and holds an image, a developer carrier that conveys the developer to a development area on the image carrier, and that is disposed in contact with and contacts the image carrier; Supplying the developer to the developer carrying member, a developer supplying member movably disposed in elastic contact with the developer carrying member, and the developer carrying member supplied from the developer supplying member. An image forming apparatus including a developing device having a thickness regulating member for regulating the thickness of the developer, wherein the developer carrying member is made of a conductive material, and its electric resistance Rd is 1 ×
10 ³ to 1 × 10 ⁸ Ω, and the developer supply member is made of a conductive material, and its electric resistance Rr has the following relationship: −4 ≦ log (Rd / Rr) ≦ 4 (log (Rd / Rr) ≠
0) is also provided.

In this image forming apparatus, the developing roller incorporated in the developing device is made of a conductor, the electric resistance Rd is set to 1 × 10 ³ to 1 × 10 ⁸ Ω, and the sponge roller for supplying toner Is also made of a conductor, and its electric resistance Rr is set to −4 ≦ log (Rd / Rr) ≦ 4
By setting (log (Rd / Rr) ≠ 0), it is possible to prevent a positive afterimage in the cycle of the developing roller. Also,
In this image forming apparatus, the smaller the difference between the electrical resistances Rd and Rr, the smaller the current flow between the developing roller and the sponge roller, and therefore, the unnecessary current is suppressed from being applied to the toner. be able to. Therefore, when this image forming apparatus is used, the toner can acquire the electric charge only by the pure frictional charge, and the bias of the electric charge of the toner is reduced, so that the selective supply of the toner can be suppressed.

In the image forming apparatus according to the present invention, the charge amount of the one-component developer on the developer carrier is preferably in the range of -40 to -60 .mu.C / g. By employing such a charge amount, it is possible to prevent a negative afterimage in the reset roller cycle and a positive afterimage in the developing roller cycle. In addition, the charge amount of the one-component developer is preferably within a predetermined time (Dr × π / Vr).
It is in the range of 30-50 C / g. That is, in the image forming apparatus of the present invention, by setting the charge amount of the toner on the developing roller to -30 to -50 [mu] C / g within a predetermined time, a negative afterimage in the reset roller cycle is prevented. can do. The present inventors have found that reaching an appropriate charge amount at the development start time and maintaining that value is the most important factor in preventing afterimages.

Further, the melt viscosity of the one-component developer used in the image forming apparatus of the present invention is preferably 1
At 00 ° C., it is 50,000 Pa · sec or less.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The image forming apparatus according to the present invention can be implemented in the following preferred embodiments. However, it should be understood that the implementation of the present invention is not limited to the following embodiments, and various changes and improvements can be made within the scope of the present invention.

The image forming apparatus according to the present invention is an image forming apparatus for an electrophotographic system for forming an image by visualizing an electrostatic latent image with a developer. This image forming apparatus includes, as described above, (1) a one-component developer contained in a developing container (toner hopper) defined by a casing;
(2) an image carrier capable of forming and holding an electrostatic latent image; and (3) an image carrier capable of transporting a developer to a development area on the image carrier, which are arranged in contact with and in contact with the image carrier. (4) a developer supply member capable of supplying the developer in the developing container to the developer support, and a developer supply member disposed elastically in contact with the developer support and movable. A thickness regulating member for regulating the thickness of the developer on the developer carrier supplied from the developer supplying member.

The above-mentioned components (1) to (5) of the developing device used in the present invention each have an arbitrary composition, as long as the requirements of the present invention can be satisfied.
It can have a configuration, a shape, and the like. Of course, each component can be a member, a device, or the like that is commonly used in a generally known electrophotographic developing device. For example, an image carrier capable of forming and holding an electrostatic latent image is a basic component of the image forming apparatus of the present invention, and is typically a photosensitive drum. For example, the photoconductor drum can be formed by using an aluminum drum as its core metal, finishing the surface of the drum to a mirror surface, and applying a layer of a photosensitive material. As the photosensitive material, for example, selenium, zinc oxide, cadmium sulfide, organic photoconductor (OPC), amorphous silicon, and the like are used.
For example, vapor deposition, coating, and the like can be used.

The developer carrier which can transport the developer to a developing area on the image carrier such as a photoreceptor drum and which is to be disposed in contact with the image carrier is preferably formed of a conductor, and is typically formed of a conductor. Specifically, it is a developing roller, a developing sleeve, or the like. For example, the developing roller can be formed by using an aluminum roller as its core metal and applying a resin coating to its surface. If necessary, a fiber brush or the like may be planted on the surface of the roller.

The developer supply member capable of supplying the developer in the developing container to the developer carrier, which is to be disposed movably in elastic contact with the developer carrier, is preferably formed of a conductor, and is typically made of a conductor. Specifically, it is a sponge roller, a fur brush, or the like. For example, a sponge roller uses an aluminum roller as its core metal, and applies a porous resin coating to the surface thereof, or substantially the entire roller is made of an elastic sponge material, for example, urethane foam. , Can be formed.

The thickness regulating member used to regulate the thickness of the developer supplied from the developer supplying member to the developer carrier is typically a thickness regulating blade or the like. it can. For example, the thickness regulating blade can be formed in various shapes from various elastic materials in order to uniformly control the thickness of the developer adhered in a thin film on the developer carrier. Examples of the material of the thickness regulating blade include an elastic rubber, a stainless steel plate, a leaf spring, and the like, which are processed into a shape (for example, a tongue-like piece, a spatula-like piece, etc.) that is easy to scrape off the toner for use. can do.

The developing device used in the present invention has, for example, a toner stirring mechanism, a toner density control mechanism, a toner replenishment mechanism, a development bias control mechanism, etc. in addition to the above-mentioned typical components. Can be. Note that these mechanisms are well known to those skilled in the art, and a description thereof will be omitted. In the image forming apparatus of the present invention, in addition to the above-described developing apparatus, a well-known apparatus necessary for performing an electrophotographic process, that is, a charging apparatus, an exposure apparatus,
A transfer device, a cleaning device, a neutralization device, a fixing device, and the like are provided. These devices are also well known to those skilled in the art and need not be described in detail here.

Further, in the embodiment of the present invention, the developer (toner) used for visualizing the electrostatic latent image is a non-magnetic one-component developer. Non-magnetic one-component developer
Since there is no need to use a carrier, there is no need for a device such as mixing and stirring of the toner, which not only has the advantage of downsizing the developing device, but also eliminates the need to mix a magnetic material into the toner. In addition, since the transparency is high and the toner can be made thin, there is an advantage that the effect and the like can be exerted for forming a full-color image. This one-component developer can basically have the same composition as a conventionally used one-component developer, and can be prepared according to a similar technique.

The binder resin serving as a main component of a one-component developer (hereinafter also referred to as “developer” or “toner”)
Includes various resin materials. Suitable binder resins include, but are not limited to, those listed below, such as polystyrene, poly p-chlorostyrene, polymers of styrene such as polyvinyl toluene, and their substituted polymers,
Styrene-p-chlorostyrene copolymer, styrene-propylene copolymer, styrene-vinyltoluene copolymer, styrene-vinylnaphthalene copolymer, styrene-
Methyl acrylate copolymer, styrene-ethyl acrylate copolymer, styrene-butyl acrylate copolymer, styrene-octyl acrylate copolymer, styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer Coalesce, styrene-butyl methacrylate copolymer,
Styrene-α-chloromethyl methacrylate copolymer, styrene-acrylonitrile copolymer, styrene-vinyl methyl ketone copolymer, styrene-butadiene copolymer, styrene-isoprene copolymer, styrene-acrylonitrile-indene copolymer , Styrene-maleic acid copolymer, styrene-based copolymer such as styrene-maleic acid ester copolymer, polymethyl methacrylate, polybutyl methacrylate, polyvinyl chloride, polyvinyl acetate, polyethylene, polypropylene, polyester,
Epoxy resin, epoxy polyol resin, polyurethane, polyamide, polyvinyl butyral, polyacrylic acid resin, rosin, modified rosin, terpene resin, aliphatic or alicyclic hydrocarbon resin, aromatic petroleum resin, chlorinated paraffin, paraffin wax, etc. Is mentioned. These binder resins may be used alone or
More than one kind may be mixed and used.

Colorants can also be used as a developer component. As the colorant, all known dyes and pigments generally used in developers can be used. Suitable coloring agents include, for example, carbon black, nigrosine dye, iron black, naphthol yellow S, Hansa yellow (10G, 5G, G), cadmium yellow, yellow iron oxide, loess, graphite, titanium yellow, poly Azo yellow, oil yellow, Hansa yellow (GR, A, RN, R),
Pigment Yellow L, Benzidine Yellow (G, G
R), Permanent Yellow (NCG), Vulcan Fast Yellow (5G, R), Tartrazine Lake, Quinoline Yellow Lake, Anthrazan Yellow BGL, Isoindolinone Yellow, Bengala, Lead Tan, Lead Zhu, Cadmium Red, Cadmium Mercury Red , Antimony Vermilion, Permanent Red 4R, Para Red, Phisaed Red, Para Chloro Ortho Nitroaniline Red,
Risor fast scarlet G, brilliant fast scarlet, brilliant kahnmin BS, permanent red (F2R, F4R, FRL, FRLL, F
4RH), Fast Scarlet VD, Belcan Fast Rubin B, Brilliant Scarlet G, Lisor Rubin GX, Permanent Red F5R, Brilliant Carmine 6B, Pigment Scarlet 3B, Bordeaux 5
B, Toluidine Maroon, Permanent Bordeaux F2
K, Helio Bordeaux BL, Bordeaux 10B, Bon Maroon Light, Bon Maroon Museum, Eosin Lake, Rhodamine Lake B, Rhodamine Lake Y, Alizarin Lake, Thioindigo Red B, Thio Indigo Maroon,
Oil red, quinacridone red, pyrazolone red, polyazo red, chrome vermillion, benzidine orange, perinone orange, oil orange, cobalt blue, cerulean blue, alkali blue lake, peacock blue lake, victoria blue lake, metal-free phthalocyanine blue, phthalocyanine blue , Fast Sky Blue, Indanthrene Blue (R
S, BC), indigo, ultramarine, navy blue, anthraquinone blue, fast violet B, methyl violet lake, cobalt violet, manganese violet, dioxane violet, anthraquinone violet, chrome green, zinc green, chromium oxide, pyridian, emerald green, pigment green B, naphthol green B, green gold, acid green lake, malachite green lake, phthalocyanine green, anthraquinone green, titanium oxide, zinc white, lithobon, and the like. These colorants may be used alone or in combination of two or more.
Although the amount of the colorant used can be changed in a wide range depending on the type of the developer to which the colorant is added, the desired effect, and the like, it is generally 0.1 to 50 parts by weight based on 100 parts by weight of the binder resin. It is in the range of parts by weight.

The developer of the present invention may contain a charge controlling agent, if necessary. As the charge control agent, any of commonly used known developers can be used. Suitable charge control agents include, for example, but are not limited to, those listed below, triphenylmethane dyes, chromium-containing metal complex dyes, molybdate chelate pigments, rhodamine dyes, alkoxy amines, alkyl Amide, phosphorus simple substance or compound, tungsten simple substance or compound,
Examples thereof include a fluorine-based activator, a metal salt of salicylic acid, and a metal salt of a salicylic acid derivative. More specifically, such charge control agents include, for example, "Bontron S-34" of a metal-containing azo dye, "E-82" of an oxynaphthoic acid-based metal complex, and "E-82" of a salicylic acid-based metal complex.
84 ", a phenolic condensate" E-89 "(all manufactured by Orient Chemical Industries, Ltd.), a triphenylmethane derivative" copy blue PR ", and a boron complex" LRA-9 ".
01 "and" LR-147 "(all manufactured by Nippon Carlit Co., Ltd.), copper phthalocyanine pigments, perylene pigments, quinacridone pigments, azo pigments, and other sulfonic acid groups,
High molecular compounds having a functional group such as a carboxyl group. These charge control agents may be used alone or in combination of two or more.

The amount of the charge control agent used in the developer is
It is determined by the toner manufacturing method including the type of the binder resin, the presence or absence of additives used as necessary, and the dispersion method, and is not limited to a specific one. 0.1 to
The range is 10 parts by weight. The use amount of the charge control agent is more preferably in the range of 2 to 5 parts by weight. If the amount of the charge control agent exceeds 10 parts by weight, the chargeability of the obtained toner becomes too large, the effect of the main charge control agent is reduced, and the electrostatic attraction with the developing roller increases, This causes a decrease in the fluidity of the developer and a decrease in image density.

In the developer used in the present invention, it is preferable that a wax is contained in the produced developer in order to impart releasability to the developer. The wax suitable for imparting releasability has a melting point in the range of 40 to 120 ° C, particularly preferably a melting point in the range of 50 to 110 ° C. If the melting point of the wax is too high, the fixability at low temperatures may be insufficient. On the other hand, if the melting point is too low, the offset resistance and durability may decrease.
The melting point of the wax is determined by a differential scanning calorimetry (DS
C). That is, the melting peak value when a few mg of sample is heated at a constant heating rate, for example (10 ° C./min), is defined as the melting point.

The wax that can be used in the developer of the present invention is not limited to those listed below, but includes, for example, solid paraffin wax,
Micro wax, rice wax, fatty acid amide wax, fatty acid wax, aliphatic monoketones, fatty acid metal salt wax, fatty acid ester wax, partially saponified fatty acid ester wax, silicone varnish,
Higher alcohols, carnauba wax and the like can be mentioned. Polyolefins such as low molecular weight polyethylene and polypropylene can also be used as waxes. In particular, the softening point (according to the ring and ball method) is 70 to 15
A polyolefin wax having a softening point in the range of 0 ° C is more preferable, and a polyolefin wax having a softening point in the range of 120 to 150 ° C is more preferable. These waxes may be used alone or as a mixture of two or more.

In the developer used in the present invention, an external additive can be used in combination. As the external additive, inorganic fine particles can be preferably used. Usually, the primary particle diameter of the inorganic fine particles is preferably from 0.005 to 2 μm, and particularly preferably from 0.005 to 0.5 μm. The specific surface area of such inorganic fine particles is 20 to 500 m ² / g when measured by the BET method.
Is preferably within the range. The usage ratio of the inorganic fine particles is 0.01 to 5.0 based on the total amount of the toner.
It is preferably in the range of 0% by mass (wt%), and more preferably in the range of 0.01 to 2.0% by mass.
Specific examples of suitable inorganic fine particles include, for example, silica,
Alumina, titanium oxide, barium titanate, magnesium titanate, calcium titanate, strontium titanate, zinc oxide, tin oxide, silica sand, clay, mica, wollastonite, diatomaceous earth, chromium oxide, cerium oxide, red iron oxide, three Examples include antimony oxide, magnesium oxide, zirconium oxide, barium sulfate, barium carbonate, calcium carbonate, silicon carbide, and silicon nitride.

Suitable external additives include, in addition to the above-mentioned inorganic fine particles, high-molecular fine particles, for example, polystyrene, methacrylic acid ester and acrylic obtained by soap-free emulsion polymerization, suspension polymerization and dispersion polymerization. Examples include acid ester copolymers, polycondensation systems such as silicone, benzoguanamine, and nylon, and polymer particles made of a thermosetting resin.

Also, a fluidizing agent (or a surface treating agent)
Are also useful as external additives. The surface treating agent increases the hydrophobicity of the toner by performing a surface treatment on the toner, and can prevent deterioration of the flow characteristics and the charging characteristics even under high humidity. For example, a silane coupling agent, a silylating agent, a silane coupling agent having a fluorinated alkyl group, an organic titanate-based coupling agent, an aluminum-based coupling agent, and the like are preferable surface treatment agents.

Further, a cleaning improver is also useful as an external additive. The cleaning property improving agent has a property of removing the developer after transfer remaining on the photosensitive drum and the primary transfer medium, that is, a function of improving the cleaning property. Suitable cleanability improvers include, for example, fatty acid metal salts such as zinc stearate, calcium stearate, and sodium stearate; for example, polymer fine particles produced by soap-free emulsion polymerization such as polymethyl methacrylate fine particles and polystyrene fine particles; and the like. Can be mentioned. Here, the polymer fine particles used as the cleaning property improver have a relatively narrow particle size distribution and a volume average particle size of 0.01 to 1 μm.
Those included in the range of m are preferred.

To further illustrate, the average particle size and particle size distribution of the toner as described above can be measured according to various conventional techniques. For example, the average particle size and particle size distribution of the toner can be measured using a Coulter Counter TA-II or a Coulter Multisizer (both manufactured by Coulter). In the present invention, measurement was carried out by using a Multisizer II (manufactured by Coulter), and connecting an interface (manufactured by Nikkaki) for outputting the number distribution and volume distribution and a PC9801 personal computer (manufactured by NEC). The electrolyte is
Prepared as 1% aqueous NaCl using primary sodium chloride. Although not used in the present invention, ISOTON-II (manufactured by Coulter Scientific Japan) can be used for the same purpose. In order to perform the measurement, a surfactant, preferably an alkylbenzene sulfonate, was added in a quantity of 0.1 to 5 ml as a dispersant to 100 to 150 ml of an aqueous electrolytic solution, and 2 to 20 mg of a measurement sample was further added. Next, the electrolytic solution in which the measurement sample is suspended is subjected to a dispersion treatment in an ultrasonic disperser for about 1 to 3 minutes,
100μ as aperture by Multisizer II
Using an m aperture, the volume of toner of 2 μm or more,
The number was measured to calculate a volume distribution and a number distribution. Then, the volume-based volume average particle diameter determined from the volume distribution according to the present invention, the volume-based coarse powder amount (12.7 μm or more) determined from the volume distribution, and the number-based fine powder amount (5 μm or less) determined from the number distribution ).

[0041]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An example in which the image forming apparatus of the present invention is applied to an electrophotographic printer will be described below. It goes without saying that the image forming apparatus of the present invention is not limited to this example. FIG. 2 is a cross-sectional view schematically showing a configuration of a developing device incorporated in the image forming apparatus of the present invention. The photosensitive drum 1 as an image carrier is rotatable in a direction indicated by an arrow (clockwise) at a peripheral speed of, for example, 60 mm / sec. On the right side of the photoreceptor drum 1, a developing device 10 as shown is provided. Further, around the photosensitive drum 1, well-known devices necessary for performing an electrophotographic process, that is, a charging device, an exposure device, a transfer device, a cleaning device, a static elimination device, a fixing device, and the like are arranged. I have. Since these devices are generally used in an image forming apparatus based on an electrophotographic process, illustration and description thereof are omitted here.

The developing device 10 includes a casing 13 having an opening facing the surface of the photosensitive drum 1,
And a developing roller 14 as a developer carrier rotatable in a direction indicated by an arrow (counterclockwise) at a predetermined peripheral speed, and an arrow in a state of being pressed against the right side of the developing roller 14. Sponge roller 15 as a developer supply member rotatable in a counterclockwise direction, and a hopper portion (also referred to as a developer container) as a developer storage means formed on the right side in casing 13. An agitator 17 for supplying the non-magnetic one-component developer (hereinafter referred to as toner) 11 to the surface of the sponge roller 15 and stirring the toner in the hopper;
A toner thickness regulating blade (usually a “doctor blade”) as a thickness regulating member for equalizing the thickness of the toner layer on the developing roller 14 conveyed to the developing area opposite to the photosensitive drum 1 by the rotation of 16).

As shown in FIG. 2, the developing roller 14 may be arranged so as to perform non-contact development opposite to the surface of the photosensitive drum 1 with a predetermined gap in the developing area. Alternatively, contact development may be performed by disposing the toner layer on the surface of the photosensitive drum 1 so as to contact the toner layer. However, in the case of contact development, if the development is absolutely constant speed, there is no speed difference between the surface of the photosensitive drum 1 and the surface of the developing roller 14, regardless of the potential of the surface of the photosensitive drum 1. Physical toner adhesion may occur.
In order to prevent this, it is preferable to set the peripheral speed of the developing roller 14 to be slightly higher than the peripheral speed of the photosensitive drum 1. For example, the peripheral speed ratio (the peripheral speed of the photosensitive drum: the peripheral speed of the developing roller) is preferably 1: 1.1 to 1: 1.5.

To the developing roller 14, an appropriate developing bias voltage, for example, DC, AC, DC superimposed AC, pulse voltage or the like is applied by a bias power supply 21. In particular, in the case of non-contact development, it is desirable to apply a voltage (alternating current, alternating current of superimposed direct current, pulse voltage, etc.) having an alternating component with good flight conditions. In the case of the present embodiment, the developing roller 14 which is formed of a conductive rubber roller and whose resistance value is set in the range of 10 ⁵ Ω to 10 ⁸ Ω in terms of axial-surface resistance is used.

The sponge roller 15 is provided with an elastic foam layer on a cored bar, and a large number of holes are opened in the surface of the elastic foam layer at least in the vicinity of the surface so as to hold the toner. . As the material of the elastic foam layer of the sponge roller 15 for supplying the toner, the developing roller 1
In order to apply a desired frictional charge to the toner 11 and the developing roller 14 by contacting the toner 4, a material that is intermediate between the material of the toner 11 and the material of the surface portion of the developing roller 14 is used in the triboelectric series. It is desirable to do. The sponge roller 15 is supported, for example, at a position where the sponge roller 15 bites into the surface of the developing roller 14 and presses against the surface, and rotates in a forward direction in which the surface moves in the same direction as the surface of the developing roller 14 at a contact portion with the developing roller 14. Driven to The linear speed of the sponge roller 15 is smaller than the linear speed of the developing roller 14.
It is desirable to set so as to be 0.9 to 1.1, preferably so as to have a constant speed. This is to prevent toner deterioration due to mechanical friction.
This is because toner deterioration can be minimized. Further, by making the diameter of the sponge roller 15 smaller than the diameter of the developing roller 14, the nip width becomes smaller and the mechanical friction can be minimized, so that the toner deterioration can be further suppressed.

The same voltage as that applied to the developing roller 14 by the bias power supply 22 or the toner triboelectrically charged to a predetermined polarity is also applied to the core metal of the sponge roller 15 from the toner supply roller 15 side by the bias power supply 22. A voltage may be applied so as to form an electric field between the developing roller 14 and the electric field that receives the electrostatic force toward the side. Agitator 17
Applies the toner 11 stored in the hopper to the sponge roller 1.
The toner is supplied to the surface of the sponge roller 5 and the toner is supplied to the surface of the sponge roller 15 by its own weight due to the shape of the hopper and the fluidity of the toner. It may be omitted.

The doctor blade 16 is arranged so as to contact the developing roller 14 with a contact pressure of about 500 to 1500 g / cm in the case of contact development. In the case of non-contact development, it is arranged with a light contact pressure of about 50% down in the case of contact. Example 1 An image forming apparatus shown in FIG. 2 and having the above-described configuration was manufactured. The details of the developing roller and the like used here are as follows. (1) Developing Roller The developing roller has an outer diameter of 1 mm in which a conductive NBR rubber layer is lined on the surface of a core metal roller having a diameter of 10 mm, and the surface is coated with a urethane coat layer of about several tens of μm.
8mm roller. The surface-to-surface resistance of this developing roller is
1 × 10 ³ Ω to 1 × 10 ⁸ Ω, preferably 1 × 10 ⁴ Ω
Ω to 1 × 10 ⁷ Ω. (2) Sponge roller A sponge roller of 14 mm in diameter having a conductive elastic foam layer on a cored roller of 8 mm in diameter, which is arranged in contact with the developing roller with a bite amount of 0.4 mm, The counter was rotated at the same linear speed as. As the conductive elastic foam layer of the sponge roller, carbon 10% by mass was used.
Was internally added and dispersed, and then foamed and molded silicone was used. The resistance of the sponge roller used in this example is in the range of 1 × 10 ² Ω to 1 × 10 ¹¹ Ω. (3) Doctor blade 0.1mm thick stainless steel leaf spring (SUS304)
An edge portion having a free length of 16 mm from the fulcrum was arranged so as to contact the developing roller with a contact pressure of 500 to 1500 g / cm. (4) Developing Bias (Bias Power Supply) A voltage of -300 V DC was applied to the developing roller, and the amount of bite into the photosensitive drum was set to 30 to 60 μm. (5) Sponge roller, doctor blade bias (bias power supply) When a bias voltage having the same polarity as the DC component of the developing bias and an absolute value greater than 100 V is applied to the core of the sponge roller, for example, when the DC component of the developing bias is -300 V,- A DC bias of 400 V was applied. A bias voltage having the same magnitude as that of the sponge roller was applied to the doctor blade. (6) Using a photoreceptor drum OPC, the latent image was uniformly charged such that the latent image became −600 ± 50 V in the background portion and −100 ± 50 V in the writing portion (image portion). (7) Toner A negatively charged toner using a non-magnetic polyester resin was prepared and used according to the following procedure. The particle size of the toner was in the range of 6 to 10 μm in number average. [Composition of Toner] Polyester resin (acid value = 3, hydroxyl group = 25, 100 parts by weight Mn = 45000, Mw / Mn = 10.0, Tg = 65 ° C.) 2 parts by weight of phthalocyanine green Carbon black (trade name “MA60”) 10 parts by weight Charge controlling agent (chromium-containing monoazo dye) 2 parts by weight [Preparation procedure] The above toner materials were mixed by a mixer, then melt-kneaded by a two-roller mill, and the kneaded product was rolled and cooled. . Thereafter, a jet plate was used to perform a collision plate type pulverizer (type I mill; manufactured by Nippon Pneumatic Industries, Ltd.) and a wind classification using a swirling flow (DS classifier; manufactured by Nippon Pneumatic Industries, Ltd.) to obtain colored particles. Further, 0.5% by mass of hydrophobic silica (trade name "H2000", manufactured by Clariant Japan KK) was added and mixed with a mixer. Example 2 Toners A, B, C, D, and D having various particle size distributions as shown in Table 1 below according to the above-described toner preparation procedure.
E, F, G and H were prepared. In order to prepare such different toners, the air pressure at the time of pulverization and the turning speed by adjusting the gap of the air inlet at the time of classification were changed. The mixed formulation of the toner material and hydrophobic silica as an external additive was all the same. The volume average particle size and the particle size distribution are values measured using a Multisizer II and an aperture diameter of 100 μm.

When the degree of the positive afterimage of each toner was compared, the results shown in Table 1 below were obtained.

[0049]

[Table 1]

Here, the positive afterimages shown in Table 1 are as follows.
The measurement was performed according to the following procedure. In this example, in addition to the positive afterimage, the measurement of the negative afterimage was also performed at the same time. First, a method for evaluating a negative afterimage will be described. The print pattern (combination of the areas A and B) shown in FIG. 3 is printed, and the print density ODa in the area A where the negative afterimage of the reset roller cycle occurs and the normal density ODn around the area are measured with an optical densitometer X-ri.
It was measured by te model 938 (manufactured by X-rite), and the average value of the four density differences ΔOD (ODn-ODa) was used as an evaluation scale for negative image lag. In the figure, x is for the developing roller cycle,
And y is the cycle of the developing roller + sponge roller.
The generation area A corresponds to the position of one rotation of the developing roller + one rotation of the reset roller from the positions of the four patch patterns at the head of printing. It was determined that the larger the density difference, the more noticeable the negative afterimage was. If confirmed visually,
When the density difference is 0.1 or less, it is difficult to identify the afterimage, and 0.0
When the value is 7 or less, almost no discrimination can be made. Therefore, it is determined that a good condition is 0.1 or less, preferably 0.07 or less.

In the case of evaluation of a positive afterimage, a print pattern similar to that of the negative afterimage was printed and used for measurement. Density ODb in area B where a positive afterimage occurs and normal density OD around it
n was measured by an optical densitometer X-rite (manufactured by X-rite), and the average value of the four density differences ΔOD (ODb-ODn) was used as an evaluation scale of the positive afterimage. The occurrence area B is
The position corresponds to one rotation of the developing roller from the positions of the four patch patterns at the head of printing. It was determined that the larger the density difference, the more pronounced the positive afterimage was. When visually confirmed, when the density difference is 0.1 or less, the afterimage is hard to be identified, and when the density difference is 0.07 or less, it is almost impossible to identify the afterimage. Therefore, it is preferable that the density difference is 0.1 or less, preferably 0.07 or less. Was determined.

As a result, it has been found that the toners A and H having a small ratio of fine powder and coarse powder have a suppressed occurrence of a positive afterimage even if they have different volume average particle diameters. As described above, according to the investigation of the present inventors, in the one-component developing method, the toner is selectively consumed from the toner having a small particle diameter due to the selective supply phenomenon. Therefore, it is considered that as the amount of toner having a small particle diameter of the toner is small, the selective supply phenomenon is less likely to occur and a positive afterimage is less likely to appear. It is obvious that the smaller the amount of the coarse powder toner that is difficult to be selectively supplied, the more advantageously the positive residual image is reduced. As described above, in the particle size distribution, a toner having a small proportion of fine powder and a small proportion of coarse powder, that is, a toner having a sharp particle diameter is overwhelmingly advantageous for reducing a positive afterimage. In this example, by defining the volume particle size in advance, it becomes possible to make it difficult to generate a positive afterimage,
Specifically, the particle size is 6 to 10 μm, the ratio of 5 μm or less is 0 to 20% by number, and the ratio of 12.7 μm or more is 0 to 2.0% by volume. It was also found that even under severe conditions in which the linear speed of the sponge roller was set to be equal to the linear speed of the developing roller, it was effective for the positive afterimage of the peripheral speed of the developing roller. Example 3 A case was examined in which the toner A and H prepared in Example 2 were used to change the shaft-surface resistance Rd of the developing roller and the surface resistance Rr of the sponge roller.

FIG. 4 shows the area where a positive afterimage occurs, in which the horizontal axis represents logRd and the vertical axis represents logRr. Further, in the drawing, the mark ○ means “no positive afterimage”, and the mark x means “with positive afterimage”. From the results in FIG. 4, -4 ≦ log (Rd / Rr) ≦ 4
(Log (Rd / Rr) ≠ 0), it was found that a good result without occurrence of a positive afterimage was obtained. Although the exact reason for obtaining such a good result has not been clarified, the smaller the difference in resistance, the smaller the current flow between the rollers, and the more unnecessary current is applied to the toner. Is considered. Therefore, it is presumed that the toner can acquire electric charge only by pure frictional charging, and the bias of the electric charge held by the toner is reduced, so that the selective supply can be suppressed. Example 4 Negative afterimages during the sponge roller cycle are presumed to occur when the charge of the toner is insufficient. Therefore, for the purpose of analysis, various toners were prepared with a prescription that reduces the charge of the toner. Further, for the analysis of the positive afterimage, the toner was prepared even under the condition that the charge of the toner was high. Specifically, the toners have the same particle size distribution as the toner A, except that the amount of the charge control agent (chromium-containing monoazo dye) is variously changed as shown in Table 2 below. K and L were prepared. In Table 2 below, the charge amount on the sleeve and the rise value of the charge amount on the sleeve are also described.

[0054]

[Table 2]

The charge amount of the toner shown in Table 2 is 2
It was measured by a blow-off method which is a method of measuring the charge amount of the component-based developer. After confirming the charge amount of the toner, in the actual device, the charge amount q / m of toner layer on the developing roller, a toner layer potential V _t and the toner layer thickness d _t, was calculated by the following equation. _{q / m = 2ε O ε r1} V t / (ρPd t 2) where, epsilon _O: dielectric constant of vacuum (8.85 × 10 ^-12 F /
m) ε _r1 : relative dielectric constant of toner layer (2.2) ρ: toner density (1.1 g / cm ³ ) P: filling rate of toner layer (constant: 0.45 assumed) V _t : toner layer Potential (variable) d _t : Toner layer thickness (variable).

As the potential of the toner layer, a value measured using a surface electrometer (trade name “Model 344”, manufactured by Trek) was used. For the thickness of the toner layer, a difference between before and after the toner layer was suctioned and removed was used as an actually measured value using a laser size measuring device (trade name “LS-5000” manufactured by Keyence Corporation). The measurement conditions are different immediately after printing and when the toner layer thickness is not so.
It was measured after printing one solid black sheet and three white solid sheets.
The measurement points of the toner layer potential and the toner layer thickness were set to be the same.

As a result, it was found that negative afterimages were less likely to occur as the charge amount of the toner was higher, and that no negative afterimages were generated at -40 μC / g or more (toners A and I,
See FIG. 5). When the same toner was used to investigate the occurrence of a positive afterimage, it was found that the positive afterimage did not occur when the charge was -60 μC / g or less (toners A and K, See FIG. 6). As described above, the area where neither the negative afterimage nor the positive afterimage is generated is −40 to −60 μC / g, and under these conditions, a condition in which neither the negative afterimage nor the positive afterimage occurs is found.

In view of the mechanism of occurrence of the negative afterimage in the sponge roller cycle, the amount of toner up to the above-mentioned charge amount is the time from when the sponge roller supplies the toner to the developing roller to when the next new toner is supplied. Needless to say, the condition is better if the surface is charged. Example 5 Toner A was prepared according to the method described in Example 2, but in this example, the acid value = 3, the hydroxyl value = 25, Mn
= 12000, Mw / Mn = 2.8 and Tg = 62 ° C. A toner M capable of expressing gloss (hereinafter, gloss toner) was obtained. The particle size distribution and external addition conditions were also set in the same manner as in the preparation of a toner A (hereinafter, referred to as a non-glossy toner) A that could not exhibit gloss.

When the viscosity of the obtained toner was measured,
The viscosity at 100 ° C. of the non-glossy toner A is 53000 Pa · se
c, the viscosity at 100 ° C. of the glossy toner M is 13000 Pa ·
sec. In addition, these viscosities are determined by molding a 1.0 g toner using a flow tester (manufactured by Shimadzu Corporation) using a special molding machine, and applying a 20 kg load to a 1 mm diameter (0.5 mm thick) die at 3 ° C./min. It is a value calculated from the outflow rate observed when the temperature is increased at the rate of. An endurance test was performed by continuous white paper running in the developing device manufactured in Example 1, and as compared with the conventional conditions, a life of about 2.7 times was achieved as shown in FIG. In addition,
In FIG. 7, OD-I is the print density of the present invention, OD-I.
II is the conventional print density, HT-I is the halftone density of the present invention, and HT-II is the conventional halftone density.

As a conventional condition for comparison, the linear speed of the sponge roller was set to 2.5 times as high as that of the developing roller by counter rotation with respect to the developing roller, and the electric resistance was 1
× 10 ¹⁰ Ω, all other conditions were the same.
The electric resistance of the developing roller was 1 × 10 ⁵ Ω, and all other conditions were the same. The other conditions of the developing device and the conditions related to image formation were all the same.

Next, when the relationship between the toner adhesion amount on the paper and the print density when the glossy toner M prepared in this example was used was measured, the results plotted in FIG. 8 were obtained. As shown in FIG. 8, since there is a linear relationship even under the condition where the amount of adhered toner is large, image defects caused by the difference in the amount of adhered image such as a negative afterimage and a positive afterimage appear more remarkably than the non-glossy toner A. It is clear that toner M has a further effect.

[0062]

As described above, according to the present invention, the amount of toner supplied from the sponge roller can be reduced while maintaining long-term stability without deteriorating image quality due to toner deterioration or increasing mechanical torque. Negative afterimage of the sponge roller cycle caused by shortage, and background fog due to unevenness of toner charge amount due to insufficient frictional charge of toner,
It is possible to provide a developing device capable of preventing a deterioration in development transfer, a deterioration in resolution, and a positive afterimage of a developing roller cycle due to a selective toner development, and a good image forming apparatus. In particular, according to the present invention, a color image forming apparatus that transmits a toner such as a color image to visually recognize a color,
As a result, further effects can be expected in a color image forming apparatus using glossy toner, which has a linear relationship between the amount of adhesion and the density.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a configuration of a developing device used in a conventional image forming apparatus.

FIG. 2 is a cross-sectional view showing a configuration of a developing device used in an image forming apparatus according to a preferred embodiment of the present invention.

FIG. 3 is a graph showing evaluation patterns of a negative afterimage and a positive afterimage.

FIG. 4 is a graph showing a relationship between resistance of a developing roller and a sponge roller and distribution of occurrence of a positive afterimage.

FIG. 5 is a graph showing a relationship between a toner charge amount on a developing roller and a density difference due to a negative afterimage.

FIG. 6 is a graph showing a relationship between a toner charge amount on a developing roller and a density difference due to a positive afterimage.

FIG. 7 is a graph showing the relationship between the number of running sheets and the change in print density (image quality).

FIG. 8 is a graph showing the relationship between the adhesion amounts of glossy toner and non-glossy toner on paper and print density.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Photoreceptor drum 10 ... Developing device 11 ... Non-magnetic toner 13 ... Casing 14 ... Developing roller 15 ... Sponge roller 16 ... Toner thickness regulating blade 17 ... Agitator 21 ... Bias power supply 22 ... Bias power supply

 ────────────────────────────────────────────────── ─── Continuing from the front page (72) Inventor Takashi Yamamoto 4-1-1, Kamidadanaka, Nakahara-ku, Kawasaki-shi, Kanagawa Prefecture Inside Fujitsu Limited (72) Inventor Shoichi Kinoshita 35-35 Saho, Shato-cho, Kato-gun, Hyogo Fujitsu Peripheral machine Inside (72) Inventor Yoshimichi Katagiri 4-1-1 Kamikadanaka, Nakahara-ku, Kawasaki City, Kanagawa Prefecture Inside Fujitsu Limited (72) Inventor Shinichi Kuramoto 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Co., Ltd. (72) Inventor Hachiro Tosaka 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Co., Ltd. (72) Inventor Hiroshi Yamashita 1-3-6 Nakamagome, Ota-ku, Tokyo Ricoh Co., Ltd. (72) Inventor Osamu Uchinokura 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Co., Ltd. (72) Inventor Kazuhiko Hamazoe 35 Saho, Shamachi, Kato-gun, Hyogo Prefecture Fujitsu Peripherals Co., Ltd. in the F-term (reference) 2H005 EA01 EA03 EA05 EA10 FA07 2H077 AC04 AD02 AD06 AD13 AD17 AD23 AD35 AE04 EA14 EA15 EA16 FA22 FA25

Claims (5)

[Claims] An image forming apparatus for visualizing an electrostatic latent image with a developer to form an image, comprising: a developing container containing a one-component developer; and an electrostatic latent image. Holding the image carrier, conveying the developer to a development area on the image carrier,
A developer carrier that is arranged in contact with the image carrier, and that supplies the developer in the developing container to the developer carrier, and is movably arranged in elastic contact with the developer carrier. An image forming apparatus comprising: a developing device having a developer supply member, and a thickness regulating member that regulates a thickness of the developer on the developer carrier supplied from the developer supply member. The developer carrier is a rotating body having an outer diameter Dd,
The surface linear velocity is Vd, and the developer supply member is a rotating body having an outer diameter Dr, and the surface linear velocity is Vr, with the following relations: Dd ≧ Dr and Vd = Vr Is satisfied, and the one-component developer is 6 to 10
consisting of particles having a volume average particle size of
The ratio of particles having a volume average particle size of not more than μm is 0 to 20.
An image forming apparatus, wherein the ratio of particles having a volume average particle diameter of 12.7 μm or more is 0 to 2% by volume. 2. An image forming apparatus for visualizing an electrostatic latent image with a developer to form an image, comprising: a developing container containing a one-component developer; and forming and holding the electrostatic latent image. Carrying the developer to a development area on the image carrier,
A developer carrier that is arranged in contact with the image carrier, and that supplies the developer in the developing container to the developer carrier, and is movably arranged in elastic contact with the developer carrier. An image forming apparatus comprising: a developing device having a developer supply member, and a thickness regulating member that regulates a thickness of the developer on the developer carrier supplied from the developer supply member. The developer carrying member is made of a conductive material, its electric resistance Rd is 1 × 10 ³ to 1 × 10 ⁸ Ω, and the developer supply member is made of a conductive material, and its electric resistance Rr
Has the following relationship: -4 ≦ log (Rd / Rr) ≦ 4 (log (Rd / Rr)}
0). 3. The image forming apparatus according to claim 1, wherein the charge amount of the one-component developer on the developer carrier ranges from -40 to -60 μC / g. . 4. The charge amount of the one-component developer is -30 to -50 μm within a predetermined time (Dr × π / Vr).
The image forming apparatus according to claim 3, wherein the value is in the range of C / g. 5. The melt viscosity of the one-component developer is 10
2. The image forming apparatus according to claim 1, wherein the temperature is 0,000 Pa.sec or less.