JP2011118193A - Developing device, developing method, image forming apparatus and image forming method - Google Patents

Abstract

The present invention provides a developing device capable of increasing development efficiency by replacing magnetic particles in which a toner has been developed with magnetic particles that have not been developed and have a high toner coverage in a developing region.
A two-component developer is carried by a developer carrier, and in the development area, the developer carrier is brought close to an image carrier on which a latent image is formed, and a developing bias is applied to the developer carrier. In the developing device 4 for developing the developer by attaching the developer to the image carrier and forming a visible image, the developer carrier is composed of a rotating non-magnetic cylindrical member, and a plurality of magnets fixedly arranged inside. 407, means for dynamically disturbing the developer layer on the developer carrier in the development region (for example, changing the magnetic field on the developer carrier by a magnetic shielding member, or lines of the developer carrier) (The speed is changed intermittently), the disturbance of the developer is promoted, the developing ability is improved, and the developing efficiency can be increased.
[Selection] Figure 3

Description

  The present invention relates to a developing device and a developing method for supplying a developer to an image carrier and developing a latent image on the image carrier, and further, an image forming apparatus including the developing device and the developing method. The present invention relates to the image forming method used.

Conventionally, an image carrier such as a photosensitive member is charged by a charging unit, a latent image is formed on the charged image carrier by a latent image forming unit, and the latent image is developed by a developing unit to be visualized. An electrophotographic image forming apparatus for transferring a visible image on the image bearing member directly to a transfer material such as paper or via an intermediate transfer member and fixing the visible image transferred to the transfer material to form an image. It is well known and is widely used as a copying machine, a printer, a plotter, a facsimile, or a complex machine of these.
As a developing device used in such an image forming apparatus, one using a two-component developer in which a toner that is a colored powder and magnetic particles (carrier) are mixed is widely used.

  As a conventional technique related to a developing device using this two-component developer, Patent Document 1 (Japanese Patent No. 3518191) discloses a developing method for the purpose of providing a two-component developing device capable of improving the resolving power as compared with the conventional one. An invention has been disclosed in which a biased wire is disposed between a roller and an image carrier to suppress disturbance of the developing electric field by the developer, improve latent image followability, and improve resolution. Yes. However, in this prior art, since the wire suspension direction is parallel to the developer transport direction, it does not become an obstacle to the developer, and the developer passes through the development area with almost no disturbance. The increase in efficiency was not very significant.

Further, in Patent Document 2 (Japanese Patent Application Laid-Open No. 2007-102122), a two-component developer containing a carrier composed of carrier particles having a relatively large particle diameter and carrier particles having a relatively small particle diameter may be used. , A developing device that fully exhibits the advantages of these carrier particles without offsetting, contributes to stably forming a high-quality image having a high image density and no image defects, and an image forming apparatus including the developing device For the purpose of providing an apparatus, a developing sleeve that conveys a two-component developer composed of toner and a carrier in a certain rotational direction, and a predetermined magnetic field that is provided inside the developing sleeve are formed. A magnetic roll composed of a plurality of magnetic poles including a developing magnetic pole, a two-component developer is accommodated together with the developing sleeve and the magnetic roll, and the two-component developer is supplied to the developing sleeve. A two-component developer using a two-component developer including carrier particles having a relatively large particle size and carrier particles having a relatively small particle size and conveyed by a developing sleeve A developing device is disclosed that includes a developer control member that applies a force to the substrate and cuts the bonding between carrier particles.
This prior art has a carrier having two types of diameters and a developer control member that cuts off the developer. However, the purpose is to arrange the arrangement of carriers having different diameters. However, it is considered that it is impossible to disturb the developer referred to in the present invention, and the development efficiency cannot be increased so much.

  The present invention has been made in view of the above circumstances. In a development system using a two-component developer, magnetic particles (carriers) in which toner has already been developed in the development region in order to obtain characteristics with high development efficiency. The present invention aims to provide a developing device and a developing method capable of increasing the developing efficiency by replacing magnetic particles (carriers) having a high toner coverage with undeveloped toner, and further, image formation provided with the developing device. It is an object of the present invention to provide an apparatus and an image forming method using the developing method.

In order to achieve the above object, the present invention employs the following solutions.
According to a first solution of the present invention, a two-component developer is carried by a developer carrier, and the developer carrier is brought close to an image carrier on which a latent image is formed in a development area. In a developing device that forms a visible image by applying a developing bias to the image carrier to develop the developer, and the developer carrier comprises a rotating non-magnetic cylindrical member and is fixed inside. It has a plurality of magnets arranged, and has means for dynamically disturbing the developer layer on the developer carrying member in the development region (claim 1).

According to a second solving means of the present invention, in the developing device of the first solving means, a magnetic shielding member is disposed on the surface side or the inner surface side of the developer carrying member, and the developer layer is dynamically moved in the developing region. (2).
According to a third solving means of the present invention, in the developing device of the first solving means, a magnetic shielding member that can be moved independently is provided on the inner surface side of the developer carrying member, and development is performed in the developing region. The agent layer is dynamically disturbed (claim 3).
Further, the fourth solving means of the present invention is the developing device of the second or third solving means, wherein the time for shielding the magnetic force by the magnetic force shielding member is one dot line with respect to the linear velocity of the developer carrier. It is smaller than the time for moving the width (claim 4).

According to a fifth solving means of the present invention, in the developing device of the first solving means, the developer layer is dynamically disturbed in the developing region by intermittently changing the linear velocity of the developer carrier. (Claim 5).
According to a sixth means of the present invention, in the developing device of the fifth means, the cycle of intermittently changing the linear velocity of the developer carrier is shorter than the ratio of the one dot line width to the linear velocity. (Claim 6).

According to a seventh solving means of the present invention, in the developing device of any one of the first to sixth solving means, a plurality of main developing magnetic poles that generate a magnetic field in the developing region are provided inside the developer carrier. In this case, the nearest point of contact between the image carrier and the developer carrier is set at a portion facing between the magnetic poles of the plurality of development main magnetic poles arranged inside the developer carrier. (Claim 7).
According to an eighth solving means of the present invention, in the developing device of any one of the first to seventh solving means, at least two kinds of magnetic particles having different average particle diameters are used as the developer. (Claim 8).
Furthermore, the ninth solving means of the present invention is characterized in that, in the developing device of the eighth solving means, at least two kinds of magnetic particles having different average particle diameters have different saturation magnetization amounts. ).
Further, the tenth solving means of the present invention is characterized in that, in the developing device of the solving means of claim 8, at least two kinds of magnetic particles having different average particle diameters have different specific gravities (claim 10). .
The eleventh solving means of the present invention is characterized in that, in the developing device of any one of the first to tenth solving means, the magnetic particles to be used have elasticity.

  According to a twelfth solution of the present invention, a two-component developer is carried on a developer carrier, and the developer carrier is brought close to an image carrier on which a latent image has been formed in a development area. In a developing method for forming a visible image by applying a developing bias to the image carrier by applying a developing bias, the developing device of any one of the first to eleventh solving means is used. The development is promoted by dynamically disturbing the developer layer on the developer carrying member in the region (claim 12).

  The thirteenth solving means of the present invention comprises an image carrier, a means for forming a latent image on the image carrier, a developing means for developing the latent image on the image carrier to make it visible, and the image In the image forming apparatus comprising means for transferring the visible image on the carrier directly to the transfer material or via the intermediate transfer body, and means for fixing the visible image transferred to the transfer material, A developing device according to any one of the first to eleventh solving means is provided (claim 13).

  According to a fourteenth solution of the present invention, a latent image is formed on an image carrier, the latent image on the image carrier is developed and visualized, and then the developed image on the image carrier is used as a transfer material. In an image forming method in which an image is formed by fixing a visible image transferred directly or via an intermediate transfer member and fixing the developed image to the transfer material, a latent image on the image carrier is developed as a twelfth method. The developing method of the solving means is used (claim 14).

In the developing devices of the first and second solving means, the disturbance of the developer is promoted because the magnetic field on the developer carrier is changed by the magnetic shielding member as means for dynamically disturbing the developer layer in the development region. As a result, the developing ability is improved and the developing efficiency can be increased.
In the developing devices of the first and third solving means, as a means for dynamically disturbing the developer layer in the developing region, the magnetic field on the developer carrying member can be changed independently under the rotation condition of the magnetic shielding member. Therefore, the disturbance of the developer is further promoted, the developing ability is improved, and the developing efficiency can be increased.
Further, in the developing device of the fourth solving means, in addition to the above effects, it is difficult to affect the image, so that the image deterioration can be suppressed.

In the developing devices of the first and fifth solving means, as the means for dynamically disturbing the developer layer in the development area, the linear velocity on the surface of the developer carrying member is intermittently changed. Disturbance is promoted by the inertia, the developing ability is improved, and the developing efficiency can be increased.
Further, in the developing device of the sixth solving means, in addition to the above effects, it is difficult to affect the image, so that it is possible to suppress image deterioration.

In the developing device of the seventh solving means, in addition to the effects of the first to sixth solving means, the restraining magnetic field in the developing area is reduced, so that the freedom of movement of the developer is further improved. Disturbance can be promoted.
In the developing device of the eighth solving means, in addition to the effects of the first to seventh solving means, by mixing magnetic particles having two kinds of average particle diameters, the movement of each magnetic particle is different and further disturbance is caused. Since it is promoted, the developing ability can be further improved.
In the developing device of the ninth solving means, in addition to the effect of the eighth solving means, the magnetic force acting on the magnetic particles is increased, and the acceleration is changed when moved. Further improvement can be achieved.
In the developing device of the tenth solving means, in addition to the effect of the eighth solving means, the force acting on the magnetic particles is increased and the disturbance can be further promoted, so that the developing ability can be further improved.
In the developing device of the eleventh solving means, in addition to the effects of the first to tenth solving means, the magnetic particles cause elastic scattering after contact with the image carrier and try to move toward the developer carrier. The development ability can be further improved.

In the developing method of the twelfth solving means, by using the developing device of any one of the first to eleventh solving means, the developer layer on the developer carrying member is dynamically disturbed in the developing region. Since the development is promoted, the same effect as any one of the first to eleventh solving means can be obtained.
In the image forming apparatus of the thirteenth solving means, the developing device of any one of the first to eleventh solving means is provided as the developing means, so that it is the same as any one of the first to eleventh solving means. Thus, an image can be formed with high development efficiency.
In the image forming method of the fourteenth solving means, the same effect as the twelfth solving means can be obtained by using the developing method of the twelfth solving means as a method of developing the latent image on the image carrier. Therefore, it is possible to perform image formation with high development efficiency.

1 is a diagram illustrating an embodiment of the present invention, and is a schematic configuration diagram illustrating a configuration example of an image forming apparatus that forms a single color image. It is a schematic whole block diagram of the image forming apparatus which shows another embodiment of this invention. 1 is a schematic configuration diagram of a developing device showing an embodiment of the present invention. It is a figure which shows an example of arrangement | positioning of the several magnet and shielding member inside a developer carrier. It is a figure which shows the relationship between the developing potential of the developing device of this invention and the conventional developing device, and the toner adhesion amount on a photoreceptor. It is a figure which shows another example of arrangement | positioning of the several magnet and shielding member inside a developer carrier. It is a figure which shows another example of arrangement | positioning of the several magnet inside a developing agent carrier. It is a figure which shows an example of the shape of the magnetic shielding member which concerns on this invention. It is a figure which shows the experimental example of the magnetic brush disturbance effect | action of the developer by a magnetic shielding member. It is a figure for demonstrating the relationship between the linear velocity difference at the time of developing a 1 dot latent image, and the frequency | count of disturbance.

  EMBODIMENT OF THE INVENTION Below, the form for implementing this invention is demonstrated based on drawing. It is easy for a person skilled in the art to make other embodiments by changing or modifying the present invention within the scope of the claims, and these changes and modifications are included in the present invention. Therefore, the following description is an example of an embodiment of the present invention and does not limit the present invention.

First, an image forming apparatus according to the present invention will be described.
FIG. 1 is a diagram illustrating an embodiment of the present invention, and is a schematic configuration diagram illustrating a configuration example of an image forming apparatus that forms a monochromatic image.
In FIG. 1, reference numeral 1 denotes a drum-shaped photoconductor as an image carrier. Around the photoconductor 1, a charging device 2, a writing device 3, a developing device 4, a transfer device 5, and a cleaning device 6 are arranged. It is installed. Further, a transfer material 20 such as a sheet is fed from a sheet feeding unit (not shown) to the transfer unit between the photosensitive member 1 and the belt-shaped transfer device 5 via a registration roller 7. Further, a fixing device 8 is provided downstream of the transfer device 5 in the transfer material conveyance direction.

  When the image forming operation is started, the photosensitive member 1 is rotated in the direction of arrow a in the figure, and a charge is applied by discharging or injection so that the charging device 2 has a uniform surface potential. Then, a light corresponding to the image information is irradiated by the writing device 3 to form a latent image. The developer carrying member 402 of the developing device 4 is in contact with the photoreceptor 1 via the developer layer in the developing region A1, and a two-component developer (colored powder) carried on the developer carrying member 402 of the developing device 4 is used. The latent image is visualized with toner composed of a body and a toner (developer mixed with magnetic particles (carrier)). The toner image visualized on the photoreceptor 1 is transferred by the transfer device 5 to a transfer material 20 fed from a paper feed unit (not shown) via a registration roller 7. After the toner image is transferred, the transfer material 20 is conveyed to the fixing device 8, and the image is fixed on the transfer material through a fixing process by the fixing device 8, and is discharged to a discharge tray (not shown). Further, residual toner and the like are removed from the photoreceptor 1 after the toner image is transferred by the cleaning blade 601 of the cleaning device 6 or the like.

Next, FIG. 2 is a schematic overall configuration diagram of an image forming apparatus showing another embodiment of the present invention, and shows an example of a tandem intermediate transfer type full-color copying machine.
The full-color copying machine includes an apparatus main body 100, a paper feed table 200 on which the main body is placed, a scanner 300 mounted on the copying machine main body, an automatic document feeder (ADF) 400 mounted on the scanner, and the like.

  In the center of the apparatus main body 100, a tandem in which four image forming units 18Y, 18C, 18M, and 18Bk corresponding to each color of yellow (Y), cyan (C), magenta (M), and black (Bk) are arranged side by side. A mold image forming apparatus 20 is configured. Each of the image forming units 18Y, 18C, 18M, and 18Bk of the tandem type image forming apparatus 20 forms toner images of respective colors of yellow (Y), cyan (C), magenta (M), and black (Bk). As shown in FIG. 1, charging devices 2Y, 2C, 1B, 1C, and 1Bk are provided around the photoconductors 1Y, 1C, 1M, and 1Bk. 2M, 2Bk, developing devices 4Y, 4C, 4M, 4Bk, primary transfer devices 5Y, 5C, 5M, 5Bk, cleaning devices 6Y, 6C, 6M, 6Bk, and the like are arranged.

  Above the tandem type image forming apparatus 20, a writing device 21 as a latent image forming unit is provided. Although not shown, the writing device 21 includes four laser diode (LD) light sources prepared for each color, an optical system that collimates a laser beam emitted from the light source, a multi-sided polygon mirror, It consists of a set of polygon scanners composed of polygon motors, fθ lenses arranged in the optical path of each light source, lenses such as long WTL, mirrors, and the like. Then, the laser light emitted from the laser diode according to the image information of each color is deflected and scanned by the polygon scanner, and is irradiated to the photoreceptors 1Y, 1C, 1M, and 1Bk of each color.

  An endless belt-like intermediate transfer member (hereinafter referred to as an intermediate transfer belt) 10 is installed below the tandem type image forming apparatus 20. In the illustrated example, the intermediate transfer belt 10 is wound around three support rollers 14, 15, 16 and can be rotated and conveyed in the clockwise direction in the drawing, and the first support roller 14 is a drive that drives the intermediate transfer belt 10 to rotate. Laura. A primary transfer roller 5Y is provided between the first support roller 14 and the second support roller 15 as a primary transfer device for transferring a toner image from the photoreceptors 1Y, 1C, 1M, and 1Bk of the respective colors to the intermediate transfer belt 10. 5C, 5M, and 5Bk are provided to face the photoreceptors 1Y, 1C, 1M, and 1Bk with the intermediate transfer belt 10 interposed therebetween. Further, an intermediate transfer belt cleaning device 17 that removes residual toner remaining on the intermediate transfer belt 10 after image transfer is provided on the downstream side of the third support roller 16 in the belt conveyance direction.

  As the material of the intermediate transfer belt 10, resin materials such as polyvinylidene fluoride, polyimide, polycarbonate, and polyethylene terephthalate can be used by molding these resin materials into a seamless belt. These materials can be used as they are, or the resistance can be adjusted with a conductive material such as carbon black. Further, using these resins as a base layer, a surface layer may be formed by a method such as spraying or dipping to form a laminated structure.

  A secondary transfer device 22 is provided below the intermediate transfer belt 10. In the illustrated example, the secondary transfer device 22 is configured by spanning a secondary transfer belt 24, which is an endless belt, between two rollers 23, and is connected to the third support roller 16 via the intermediate transfer belt 10. The image on the intermediate transfer belt 10 is transferred to a transfer material by being pressed. As the secondary transfer belt 24, the same material as that of the intermediate transfer belt 10 can be used.

Next to the secondary transfer device 22, a fixing device 25 for fixing an image on the transfer material is provided. The fixing device 25 is configured by pressing a pressure roller 27 against a fixing belt 26 that is an endless belt, and has a heating source for a roller or the like that supports the fixing belt 26.
The secondary transfer device 22 described above is also provided with a sheet transport function for transporting the transfer material after image transfer to the fixing device 25. Of course, a transfer roller or a transfer charger may be disposed as the secondary transfer device. In such a case, it is necessary to separately provide this transfer material conveying function. In the illustrated example, the transfer material is reversed and discharged under the secondary transfer device 22 and the fixing device 25 in parallel with the tandem image forming device 20 described above, or an image is formed on both surfaces of the transfer material. And a reversing device 28 for reversing and transferring the transfer material.

When copying using this full-color copying machine, a document is set on the document table 30 of the ADF 400. Alternatively, the ADF 400 is opened and an original is set on the contact glass 32 of the scanner 300, and the ADF 400 is closed and the original is pressed.
When a start switch of an operation unit (not shown) is pressed, when a document is set on the ADF 400, the scanner 300 is driven after the document is transported and moved onto the contact glass 32. When the document is set, the scanner 300 is immediately driven to travel on the first traveling body 33 that holds the light source and the first mirror, and the second traveling body 34 that holds the second mirror and the third mirror. Then, the first traveling body 33 emits light from the light source and the reflected light from the document surface is reflected by the first mirror toward the second traveling body 34, and the second and third mirrors of the second traveling body 34. Then, the light is reflected into the reading sensor 36 such as a CCD through the imaging lens 35, and the reading sensor 36 reads the content of the original. Thereafter, when the mode setting is set in the operation unit or the automatic mode selection is set in the operation unit, the image forming operation is started in the full color mode or the monochrome mode according to the reading result of the original.

  Here, when the full color mode is selected, the photosensitive members 1Y, 1C, 1M, and 1Bk of the image forming units 18Y, 18C, 18M, and 18Bk of the tandem type image forming apparatus 20 are counterclockwise in FIG. Rotate respectively. The surfaces of the photoreceptors 1Y, 1C, 1M, and 1Bk are uniformly charged by the charging devices 2Y, 2C, 2M, and 2Bk. The photoconductors 1Y, 1C, 1M, and 1Bk of the respective colors are respectively irradiated with laser beams corresponding to the respective color images from the writing device 21, and latent images corresponding to the image data of the respective colors are formed. Each latent image is developed by the toner of each color in the two-component developer carried on the developer carrier of each color developing device 4Y, 4C, 4M, 4Bk as the photoreceptors 1Y, 1C, 1M, 1Bk rotate. Visualized. The toner images of the respective colors are sequentially transferred onto the intermediate transfer belt 10 by the primary transfer rollers 5Y, 5C, 5M, and 5Bk along with the conveyance of the intermediate transfer belt 10 to form a full color image on the intermediate transfer belt 10.

  On the other hand, one of the paper feed rollers 42 of the paper feed table 200 is selectively rotated to feed a transfer material such as paper from one of the paper feed cassettes 44 provided in multiple stages into the paper feed table 43, and one sheet is separated by the separation roller 45. The paper is separated and put into a paper feed path 46, transported by a transport roller 47, guided to a paper feed path 48 in the main body, and abutted against a registration roller 49 and stopped. Alternatively, the transfer roller 50 is rotated to feed the transfer material on the manual feed tray 51, separated one by one by the separation roller 52, put into the manual feed path 53, and abutted against the registration roller 49 and stopped. Then, the registration roller 49 is rotated in synchronization with the full-color image on the intermediate transfer belt 10, the transfer material is fed between the intermediate transfer belt 10 and the secondary transfer device 22, and transferred by the secondary transfer device 22. The toner image is transferred onto the transfer material.

  The transfer material onto which the toner image has been transferred is conveyed by the secondary transfer belt 24 of the secondary transfer device 22 and sent to the fixing device 25. The fixing device 25 applies heat and pressure to form the toner image on the transfer material. After fixing, the sheet is switched by the switching claw 55, discharged by the discharge roller 56, and stacked on the discharge tray 57. Alternatively, the sheet is switched by the switching claw 55 and put into the sheet reversing device 28, where it is reversed and re-fed to the secondary transfer position 22, and an image is recorded on the back side. To be discharged. Thereafter, when the formation of two or more images is instructed, the above-described image forming process is repeated.

  Next, when the monochrome mode is selected, the support roller 15 moves downward to separate the intermediate transfer belt 10 from the photoreceptors 1Y, 1C, and 1M. Then, only the black (Bk) photosensitive member 1Bk rotates counterclockwise in FIG. 1, and the surface of the black (Bk) photosensitive member 1Bk is uniformly charged by the charging device 2Bk. A latent image is formed by irradiating a laser beam corresponding to the image, and is developed with the Bk toner in the two-component developer carried on the developer carrying member of the developing device 4Bk to form a toner image. This toner image is transferred onto the intermediate transfer belt 10. At this time, the three color photoconductors 1Y, 1C, and 1M other than Bk and the developing devices 4Y, 4C, and 4M are stopped, and unnecessary wear of the photoconductor and the developer is prevented.

  On the other hand, the transfer material is fed from the paper feed cassette 44 in the paper feed table 43 and is conveyed to the secondary transfer device 22 by the registration roller 49 at the same timing as the toner image formed on the intermediate transfer belt 10. The The transfer material onto which the toner image has been transferred by the secondary transfer device 22 is fixed by the fixing device 25 as in the case of a full-color image, and processed through a paper discharge system corresponding to the designated mode. Thereafter, when the formation of two or more images is instructed, the above-described image forming process is repeated.

The image forming apparatus having the configuration shown in FIG. 1 and each image forming unit of the image forming apparatus shown in FIG. 2 have substantially the same configuration. In the developing method and the developing apparatus according to the present invention used for these, A two-component developer used for the contact or non-contact development method is used. Various known ones are used for the contact or non-contact development method. In the present invention, a developing sleeve (for example, a sleeve made of aluminum or SUS) that is a rotating cylindrical member is used as the developer carrier. In the developing sleeve, a plurality of magnets (or a plurality of magnetic poles) are fixedly arranged, and further, development is performed in a developing region where the developer carrying member and the image carrying member (photosensitive member) face each other. Means are provided for dynamically disturbing the layer.
In Example 1 shown below, the operation and effect of the configuration using a magnetic shielding member will be described as means for dynamically disturbing the developer layer, and in Example 2, means for disturbing the developer layer. The operation and effect of the configuration using intermittent changes in the rotation speed of the developer carrier will be described. In the following description, the two-component developer is described as magnetic particles (carrier) + toner.

[Example 1]
Since the image forming apparatus having the configuration shown in FIG. 1 and each image forming unit of the image forming apparatus shown in FIG. 2 have substantially the same configuration, the description will be made using the configuration of FIG.
In the development area A1, the gap between the photoreceptor 1 as an image carrier and the developer carrier 402 is set to 300 [μm].
At this time, since an electric field is formed between the developer carrying member 402 and the photosensitive member 1 by the latent image and the developing bias, the toner image on the developer layer is visualized by adhering to the latent image.
Under these conditions, the toner adhesion amount was 0.3 [mg / cm ² ] and the charge amount was −21 [μC / g] on average in the solid portion.
Thereafter, an image is formed through a transfer and fixing process as appropriate.

  The toner used in the developing method and the developing apparatus according to the present invention is advantageous in that the average particle diameter of the toner is 4 to 8 μm in order to realize a high-quality image. When the weight average particle size is less than 3 μm, there are problems such as contamination inside the machine due to toner scattering during long-term use, image density reduction in a low-humidity environment, and poor photoreceptor cleaning. When the weight average particle diameter exceeds 8 μm, the resolution of a fine spot of 100 μm or less is not sufficient, and the image quality tends to be inferior when scattering to a non-image portion occurs.

Here, details of the toner are shown below.
As the resin constituting the toner, polystyrene resin, epoxy resin, polyester resin, polyamide resin, styrene acrylic resin, styrene methacrylate resin, polyurethane resin, vinyl resin, polyolefin resin, styrene butadiene resin, phenol resin, polyethylene resin, silicon resin, Examples include butyral resin, terpene resin, and polyol resin. Examples of vinyl resins include styrene such as polystyrene, poly-p-chlorostyrene, and polyvinyltoluene, and homopolymers thereof: styrene-p-chlorostyrene copolymer, styrene-propylene copolymer, styrene-vinyltoluene copolymer. Polymer, styrene-vinyl naphthalene copolymer, styrene-methyl acrylate copolymer, styrene-ethyl acrylate copolymer, styrene-butyl acrylate copolymer, styrene-octyl acrylate copolymer, styrene-methacrylic copolymer Acid methyl copolymer, styrene-ethyl methacrylate copolymer, styrene-butyl methacrylate copolymer, styrene-α-chloromethyl methacrylate copolymer, styrene-acrylonitrile copolymer, styrene-vinyl methyl ether copolymer Coalescence, styrene-vinyl ethyl acetate Copolymer, styrene-vinyl methyl ketone copolymer, styrene-butadiene copolymer, styrene-isoprene copolymer, styrene-acrylonitrile-indene copolymer, styrene-maleic acid copolymer, styrene-maleic acid ester Styrene copolymers such as copolymers: polymethyl methacrylate, polybutyl methacrylate, polyvinyl chloride, polyvinyl acetate and the like.

  The polyester resin is composed of a dihydric alcohol as shown in the following group A and a dibasic acid salt as shown in the group B, and further a trihydric or higher alcohol as shown in the group C or Carboxylic acid may be added as a third component.

  Group A: ethylene glycol, triethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4 butanediol, neopentyl glycol, 1,4 butenediol, 1,4-bis (hydroxymethyl) cyclohexane Bisphenol A, hydrogenated bisphenol A, polyoxyethylenated bisphenol A, polyoxypropylene (2,2) -2,2′-bis (4-hydroxyphenyl) propane, polyoxypropylene (3,3) -2, 2-bis (4-hydroxyphenyl) propane, polyoxyethylene (2,0) -2,2-bis (4-hydroxyphenyl) propane, polyoxypropylene (2,0) -2,2′-bis (4 -Hydroxyphenyl) propane and the like.

  Group B: maleic acid, fumaric acid, mesaconic acid, citraconic acid, itaconic acid, glutaconic acid, phthalic acid, isophthalic acid, terephthalic acid, cyclohexanedicarboxylic acid, succinic acid, adipic acid, sebacic acid, malonic acid, linolenic acid, or These acid anhydrides or esters of lower alcohols.

  Group C: Trivalent or higher alcohols such as glycerin, trimethylolpropane and pentaerythritol, and trivalent or higher carboxylic acids such as trimellitic acid and pyromellitic acid.

  As the polyol resin, an alkylene oxide adduct of an epoxy resin and a dihydric phenol, or a compound having one active hydrogen in the molecule that reacts with the glycidyl ether and the epoxy group, and an active hydrogen that reacts with the epoxy resin in the molecule. There are those obtained by reacting two or more compounds.

As the pigment used in the toner in the present invention, the following are used.
Examples of black pigments include azine dyes such as carbon black, oil furnace black, channel black, lamp black, acetylene black, and aniline black, metal salt azo dyes, metal oxides, and composite metal oxides.
Examples of yellow pigments include cadmium yellow, mineral fast yellow, nickel yellow, navel yellow, naphthol yellow S, hansa yellow G, hansa yellow 10G, benzidine yellow GR, quinoline yellow lake, permanent yellow NCG, and tartrazine lake. .

Examples of the orange pigment include molybdenum orange, permanent orange GTR, pyrazolone orange, vulcan orange, indanthrene brilliant orange RK, benzidine orange G, and indanthrene brilliant orange GK.
Examples of red pigments include Bengala, Cadmium Red, Permanent Red 4R, Resol Red, Pyrazolone Red, Watching Red Calcium Salt, Lake Red D, Brilliant Carmine 6B, Eosin Lake, Rhodamine Lake B, Alizarin Lake, Brilliant Carmine 3B.

Examples of purple pigments include fast violet B and methyl violet lake.
Examples of blue pigments include cobalt blue, alkali blue, Victoria blue lake, phthalocyanine blue, metal-free phthalocyanine blue, phthalocyanine blue partially chlorinated, first sky blue, and indanthrene blue BC.
Examples of green pigments include chrome green, chromium oxide, pigment green B, and malachite green lake.

  These can use 1 type (s) or 2 or more types. Especially for color toners, uniform dispersion of good pigments is essential. Instead of putting pigments directly into a large amount of resin, a master batch in which pigments are once dispersed at a high concentration is prepared and diluted. The method of throwing in is used. In this case, a solvent is generally used to assist dispersibility. However, there is a problem of environment and the like, and in the present invention, water is used for dispersion. When water is used, temperature control is important so that residual moisture in the masterbatch does not become a problem.

  In the toner of the present invention, a charge control agent is blended (internally added) inside the toner particles. The charge control agent makes it possible to control the optimum charge amount according to the development system. In particular, in the present invention, the balance between the particle size distribution and the charge amount can be further stabilized. For controlling the toner to be positively charged, nigrosine and quaternary ammonium salts, triphenylmethane dyes, imidazole metal complexes and salts can be used alone or in combination of two or more. Further, salicylic acid metal complexes, salts, organic boron salts, calixarene compounds, and the like are used for controlling the toner to be negatively charged. Further, a release agent can be internally added to the toner in the present invention to prevent offset at the time of fixing. Release agents include natural waxes such as candelilla wax, carnauba wax, rice wax, montan wax and derivatives thereof, paraffin wax and derivatives thereof, polyolefin wax and derivatives thereof, sazol wax, low molecular weight polyethylene, and low molecular weight polypropylene. And alkyl phosphate esters. The melting point of these release agents is preferably 65 to 90 ° C. When the temperature is lower than this range, blocking during storage of the toner tends to occur, and when the temperature is higher than this range, an offset is likely to occur in a region where the fixing roller temperature is low.

  An additive may be added to the toner for the purpose of improving the dispersibility of a release agent or the like. As additives, styrene acrylic resin, polyethylene resin, polystyrene resin, epoxy resin, polyester resin, polyamide resin, styrene methacrylate resin, polyurethane resin, vinyl resin, polyolefin resin, styrene butadiene resin, phenol resin, butyral resin, terpene resin, There is a polyol resin or the like, and a mixture of two or more of these resins may be used.

As the resin, crystalline polyester may be used. It is an aliphatic polyester having crystallinity, having a sharp molecular weight distribution, and increasing the absolute amount of its low molecular weight as much as possible. This resin undergoes a crystal transition at the glass transition temperature (Tg), and at the same time, the melt viscosity suddenly decreases from the solid state and exhibits a fixing function to paper. By using this crystalline polyester resin, low-temperature fixing can be achieved without excessively reducing the Tg and molecular weight of the resin. Therefore, there is no decrease in storage stability associated with a decrease in Tg. Further, there is no excessively high gloss and offset resistance deterioration due to the low molecular weight. Therefore, the introduction of the crystalline polyester resin is very effective for improving the low-temperature fixability of the toner.
The circularity of the toner particles was measured as an average circularity by a flow type particle image analyzer FPIA-1000 (manufactured by Toa Medical Electronics Co., Ltd.).

In the toner of the present invention, an inorganic fine powder is adhered or fixed to the toner surface as a fluidity improver. The average particle size of the inorganic fine powder is suitably 10 to 200 nm. When the particle size is smaller than 10 nm, it is difficult to produce an uneven surface having an effect on fluidity, and when the particle size is larger than 200 nm, the powder shape becomes rough, resulting in a problem of toner shape.
As the inorganic fine powder of the present invention, Si, Ti, Al, Mg, Ca, Sr, Ba, In, Ga, Ni, Mn, W, Fe, Co, Zn, Cr, Mo, Cu, Ag, V, Zr, etc. And oxides and composite oxides. Of these, fine particles of silicon dioxide (silica), titanium dioxide (titania), and alumina are preferably used. Furthermore, it is effective to perform a surface modification treatment with a hydrophobizing agent or the like. Typical examples of the hydrophobizing agent include the following.
Dimethyldichlorosilane, trimethylchlorosilane, methyltrichlorosilane, allyldimethyldichlorosilane, allylphenyldichlorosilane, benzyldimethylchlorosilane, bromomethyldimethylchlorosilane, α-chloroethyltrichlorosilane, p-chloroethyltrichlorosilane, Chloromethyldimethylchlorosilane, chloromethyltrichlorosilane, hexaphenyldisilazane, hexatolyldisilazane, etc.

The inorganic fine powder is preferably used in an amount of 0.1 to 2% by weight based on the toner. If it is less than 0.1% by weight, the effect of improving toner aggregation is poor, and if it exceeds 2% by weight, problems such as toner scattering between fine wires, contamination in the machine, scratches and abrasion of the photoreceptor tend to occur. is there.
In addition, a charge control agent may be attached or fixed to the surface of at least a powder composed of a resin and a pigment so that the powder surface shape has a small period and a large period. The average particle size is optimally as small as 10 to 200 nm. When the particle size is smaller than 10 nm, it is difficult to produce an uneven surface having an effect on fluidity, and when the particle size is larger than 200 nm, the powder shape becomes rough, resulting in a problem of toner shape.
In addition, the toner of the present invention may further contain other additives, for example, a lubricant powder such as Teflon (registered trademark) powder, zinc stearate powder, polyvinylidene fluoride powder; Abrasives such as powder, silicon carbide powder and strontium titanate powder can also be used in small amounts as a developability improver.
In addition, this evaluation method can also be used for toners and capsule toners produced by a spray-drying method produced without using a kneading step or a pulverizing step.

The toner resistance is adjusted by including and dispersing a conductive material. In the case of carbon materials, acetyl black, oil furnace black, thermal black, carbon fiber, graphite and the like can be raised. In the metal system, there are metal powders such as tin oxide (SnO ₂ ), zinc oxide (ZnO), Cu, and Ni. Resistance can be adjusted by appropriately dispersing this in a toner binder resin.

  The particles (carrier) having magnetism used in the two-component development have a diameter of 20 to 80 [μm], the base has a magnetic material, and the surface layer efficiently imparts charge by toner and frictional charging. Is coated with a material that is easily charged to a polarity opposite to that of the toner. Specifically, materials including silicon resin and ammonium dioxide can be raised. Furthermore, styrene-acrylic resin, epoxy resin, styrene-butadiene resin, butyral resin, and styrene resin can be raised. The base ferrite material is fired at 1250 to 1300 ° C. for 3 to 5 hours, pulverized with a crusher or the like, and has a desired particle size distribution. In order to reduce the mass of the carrier, the base can be used as a resin and magnetic particles can be mixed.

  When the developer carrier is made of a stainless steel (SUS) sleeve (or an aluminum sleeve) and has permanent magnets with irregularities inside, the surface layer is roughened by sandblasting or the like, and the surface roughness is The range of about 10 to 30 [μm] is good, and if it becomes rougher than this, the holding amount increases extremely and the charge amount of the toner decreases. On the other hand, if it is less than 10 [μm], a sufficient amount of developer cannot be maintained, resulting in a decrease in developing ability.

Here, the developer carrying member is configured such that a sleeve, which is an external cylindrical member, rotates, and an independently rotatable magnetic shielding member disposed on the inner surface side of the sleeve also rotates. In the present embodiment, the sleeve has a diameter of 18 mm, and a cylindrical member is used in which a magnetic material is attached in a strip shape in a direction perpendicular to the rotation direction. In this embodiment, the interval is set to about 3 [mm], and the width of the portion to which the magnetic material is applied is set to 2 [mm]. [mm / s].
Also, instead of depositing a strip-shaped magnetic body, a cylindrical member made of a magnetic material is formed with slit-like openings at equal intervals (a magnetic shielding member shown in FIG. 8 described later). Can also be used as a magnetic shielding member.

  Further, apart from these, for example, a magnetic shielding member having a strip shape or a slit shape may be attached to the sleeve surface (or the inner surface) of the developer carrier, and in this case, as the developer carrier rotates. Since the action of changing the magnetic field can be caused, the same effect can be obtained. Of course, by adopting the above-described independently rotatable configuration, it becomes easier to control the change of the magnetic field, so that it is possible to set conditions according to the disturbance function of the developer.

It has already been described that the magnetic particles (carrier) of the developer contain a magnetic material such as ferrite with a metal or resin as a core, and the surface layer is coated with a silicon resin or the like. The particle size of the magnetic particles is preferably in the range of 20 to 80 μm. The resistance of the magnetic particles is preferably in the range of 10 ⁸ to 10 ¹² Ω in terms of dynamic resistance DR. Here, the measurement of the dynamic resistance DR of the magnetic particles was performed as follows using a measuring apparatus.
First, a rotatable sleeve having a diameter of 20 mm with a fixed magnet built in a predetermined position is set above the grounded pedestal. A counter electrode (doctor) having a facing area with a width W = 65 mm and a length L = 0.5 to 1 mm is opposed to the surface of the sleeve with a gap g = 0.9 mm. Next, the sleeve is rotationally driven at a rotational speed of 600 rpm (linear speed: 628 mm / sec). Then, a predetermined amount (14 g) of the magnetic particles to be measured is supported on the rotating sleeve, and the magnetic particles are stirred for 10 minutes by the rotation of the sleeve. Next, the current IRII [A] flowing between the sleeve and the counter electrode is measured with an ammeter in a state where no voltage is applied to the sleeve. Next, an applied voltage E [V] of a withstand voltage upper limit level (400 V for high-resistance silicon-coated carrier to several V for iron powder carrier) is applied to the sleeve from a DC power source for 5 minutes (200 V is applied in this embodiment). Then, the current IRQ [A] flowing between the sleeve and the counter electrode with the voltage E applied is measured with an ammeter. From these measurement results, the dynamic resistance DR [Ω] is calculated using the following equation.
DR = E / (I _RQ -I _RII )

  Next, a configuration example of the developing device 4 will be described in more detail with reference to FIG. The developer carrier 402 is a non-magnetic and rotatable sleeve in which a magnet member 407 having a plurality of magnetic poles is incorporated. The magnet member 407 is fixedly arranged so that a magnetic force acts when the developer passes a predetermined portion on the developer carrier 402. The developer carrier 402 used in this example is a SUS sleeve (or aluminum sleeve) having a diameter of φ18 mm so that the surface roughness Rz (ten-point average roughness) falls within the range of 10 to 20 μm. Sandblasted.

  The magnet member 407 built in the developer carrier 402 is, for example, N pole (N1), S pole (S1), N pole (N2), S in the direction of rotation of the developer carrier 402 from a restriction position by the restriction blade 404. Four magnetic poles of the pole (S2) are arranged. The arrangement of the magnetic poles of the magnet member 407 is not limited to the four-pole configuration of FIG. 3 or FIG. 4 to be described later, and other arrangements are possible depending on the arrangement of the regulating blade 404 around the developer carrier 402 and the like. The arrangement may be set, or a multipolar configuration having a larger number of magnetic poles may be employed. For example, as shown in FIG. 6, a five-pole configuration having two developing main magnetic poles (developing magnets) that generate a magnetic field in the developing region may be employed. Moreover, it is good also as a multipolar structure with many more magnetic poles like the example shown in FIG. FIG. 7 shows an example in which four developing main magnetic poles (developing magnets) that generate a magnetic field in a developing region facing the image carrier (photosensitive member) are arranged. The direction of the magnetic pole of each magnet, and N and S surrounded by a square are the magnetic poles facing the surface side of the developer carrier. As shown in FIGS. 6 and 7, in the case of a configuration having a plurality of main developing magnetic poles inside the developer carrying member 402, the image carrying member is disposed at a portion facing between the magnetic poles of the plurality of developing main magnetic poles. 1 and the closest point of contact between the developer carrier 402 are set. By setting in this way, the restraining magnetic field at the closest point in the development area is reduced, so that the shielding effect by the magnetic shielding member 403 is improved, and the degree of freedom of movement of the developer is further improved, so that disturbance can be promoted.

In the developing device 4 of the present invention, the developer composed of toner and magnetic particles is supported on the developer carrier 402 in a brush shape by the magnetic force of the plurality of magnet members 407 as described above. The toner in the magnetic brush on the developer carrier 402 is mixed with magnetic particles to obtain a specified charge amount. Further, the toner is agitated by the rotational force of the agitating / conveying members 405 and 406 and the developer carrier 402 in the developing device 4 and the magnetic force of the magnet member 407, and at this time, the toner is charged by frictional charging with the magnetic particles. The
The charge amount of the toner on the developer carrier 402 is preferably in the range of −10 to −40 [μC / g].

  In this embodiment, the distance at the closest portion between the regulating blade 404 and the developer carrier 402 is set to 300 μm, and the magnetic pole N1 of the magnet member 407 facing the regulating blade 404 is positioned at the position facing the regulating blade 404. Further, the developer carrier 402 is positioned at an angle of several degrees on the upstream side in the rotation direction. Thereby, the circulation flow of the developer in the casing can be easily formed.

  The regulation blade 404 is in contact with the magnetic brush so as to regulate the amount of developer formed on the developer carrier 402 at a portion facing the developer carrier 402, so that a predetermined amount of developer is carried and conveyed. In addition, frictional charging between the toner in the developer and the magnetic particles is promoted.

  Here, in this embodiment, as shown in FIG. 4 or FIG. 6, a slit-shaped (or strip-shaped) magnetic shielding member 403 is disposed inside the sleeve of the developer carrier 402 and along the inner surface of the sleeve. Are configured to move. As an example of the shape of the magnetic shielding member 403, as shown in FIG. 8, a member formed in a cylindrical shape using a magnetic material and provided with slits (openings) at a predetermined interval can be used. On the contrary, a strip-shaped magnetic material may be attached to a cylindrical member of a nonmagnetic material at a predetermined interval.

  A magnetic field is formed on the surface of the developer carrier 402 by a fixed magnet 407 disposed in the developer carrier 403, but the magnetic field changes with time by the moving magnetic shielding member 403. Due to the change in the magnetic field, the developer in the developing region near the photoreceptor 1 is urged to the photoreceptor 1 or the action of pulling back is applied in a short time, so that the carrier particles in the developer move, thereby developing the developer. Dynamic disturbance occurs in the layer, and in particular, once developed carrier particles are replaced with carrier particles having a high toner coverage, thereby increasing the probability of being close to the photoreceptor 1, resulting in an increase in development efficiency. Connected.

Here, FIG. 10 shows an experimental example of the magnetic brush disturbing action of the developer by the magnetic shielding member.
In this experiment, as shown in FIG. 10A, as a magnetic shielding member, a 27 [mm] × 91 [mm] sheet-like magnetic material is provided with a slit (opening) having a width of 3 [mm] of 3 [mm]. The ones provided at intervals were used.
Then, as shown in FIG. 10 (b), a developer containing a mixture of magnetic particles (carrier) and toner is put into a screw tube bottle, and a magnetic shielding member (of magnetic material) is formed along the lower outer surface of the screw tube bottle. A magnetic brush was formed by disposing a magnet and a magnet below the sheet.

Next, in the state of FIG. 10B, the magnetic shielding member (magnetic material sheet) was reciprocated along the lower outer surface of the screw tube bottle to verify whether the magnetic brush was disturbed.
As a result of this verification, when one sheet of magnetic material was used, the magnetic brush formed by the magnetic force of the magnet did not move. However, as shown in FIG. The height of the magnetic brush has changed.
That is, the effect of reducing the magnetic force was weak because the magnetic shielding effect was low with one sheet of magnetic material, and the magnetic brush did not move. However, by stacking two sheets, the magnetic shielding ability appeared and the magnetic brush could be moved. did it.

  From the above experimental results, the magnetic shielding member is formed of a magnetic material having an appropriate thickness that exhibits the magnetic shielding effect, and this magnetic shielding member is disposed between the magnet and the developer carried on the developer carrier (sleeve). Since it has been verified that the magnetic brush moves in the vertical direction by moving the magnetic field, the developer in the developing region can be sufficiently used as a means for dynamically disturbing the developer.

  The magnetic shielding member 403 used in this embodiment is preferably made of iron as a material, and acts so as to take in the magnetic force and prevent it from leaking outside. Therefore, the magnetic force of the fixed magnet 407 in the developer carrier 402 is weakened. Normally, the developer follows a predetermined waveform, but by changing the waveform in both time and place by the magnetic shielding member 403, the direction of movement of the developer changes and the developer dynamically It is a disturbance.

  In this embodiment, the developer carrying member 402 is rotationally driven at a linear speed of 360 mm / s with respect to the linear speed of the photosensitive member 1 of 200 mm / s. As an example, the slits of the magnetic shielding member 403 are arranged at intervals of 3 [mm] in the circumferential direction of the developer carrier 402, and the magnetic shielding material is formed with a width of 3 [mm]. Is 500 [mm / s] in the reverse direction. As a result, 287 [Hz] becomes the vibration frequency of the magnetic brush, and this movement increases the probability that the magnetic particles having a high toner coverage ratio come into contact with the photosensitive member 1, thereby obtaining a high-quality image due to the high development ability. be able to.

  In this embodiment, the magnetic particles (carriers) used have different average particle diameters. The properties are shown below, but the materials are the same and only the particle size is different. The amount of saturation magnetization of the magnetic particles varies depending on the particle diameter. Also, since the mass is different, the behavior in the magnetic field is different. First, since the saturation magnetization amount is different, the magnetic material is attracted by a stronger magnetic force when approaching the fixed magnet in the developer carrying body, so that it collides with other magnetic particles as a result, thereby promoting disturbance. Further, when the mass is relatively large, the force at the time of collision becomes strong, and it becomes possible to efficiently disturb the already existing developer layer. Thus, in this embodiment, the disturbance of the developer layer in the development region can be promoted by combining magnetic particles having different particle sizes.

  In this example, a ferrite material is used for a base having a grain size of 75 [μm] and a saturation magnetization of 80 to 100 [emu / g], and the other has a grain size of 25 [μm] and a saturation magnetization of Manufactured using a ferrite material for a base of 65 to 75 [emu / g], and the latter was mixed at 50 [wt%] with the latter 50 [wt%].

As shown in FIG. 5, the development potential is plotted on the horizontal axis, the toner adhesion amount on the photosensitive member is plotted on the vertical axis, and the slope is compared. In the conventional two-component developer, 1.4 [(mg / cm ²⁾ / kV] relative to become, in the present invention ^{2.5 [(mg / cm 2)} / value of kV] has been obtained, developability is improved by disrupting the developer according to the invention It can be seen that the development efficiency has increased.

  Since the toner of the developer layer is sufficiently charged, the toner adhering to the carrier of the developer layer is in a considerably high coverage ratio. In this state, the developer carried on the developer carrier 402 is conveyed to the development area by the rotation of the developer carrier 402. Then, by the developing electric field formed by the developing bias, the electrostatic latent image on the photosensitive member 1 is selectively attached to the electrostatic latent image, and the electrostatic latent image is developed.

Details of the relationship between the number of disturbances with respect to a one-dot image when developing a latent image will be described with reference to FIG.
If the developer disturbance target is at least once when the developer passes through the latent image, the resolution of 600 [dpi] is about 42 [μm] when the dot width is S [μm]. At this time, if the linear velocity of the photosensitive member 1 is vPC and the linear velocity of the developer carrying member (hereinafter referred to as a developing roller) 402 is vDR (rotating), the linear velocity difference is vDR-vPC, so that a one-dot image is obtained. The passing time T can be expressed by the following equation (when the magnetic shielding member is fixed to the sleeve of the developing roller).
T = S × 10−3 [mm] / | vPC−VDR | [mm / s]

As shown in FIG. 9, when the dot width is 42 [μm], the photosensitive member linear velocity is vPC = 200 [mm / s], and the developing roller linear velocity is vDR = 300 [mm / s], the developer Since the latent image is moved with a linear velocity difference of 100 [mm / s], it is 0.25 × 10 ⁻⁴ [s], which is F = T ⁻¹ = 2.5 [kHz] in frequency.
However, since the development nip width of the development area is about 4 [mm], the time for the latent image to pass is
4 [mm] / 200 [mm / s] = 2 × 10 ⁻² [s]
Therefore, 50 [Hz] or more is sufficient.
At this time, considering the slit width of the magnetic shielding member 403, 50 [Hz] becomes 0.02 [s] in time, so the length of the magnetic shielding member 403 with or without the linear velocity difference of 100 [mm / s]. When the length is calculated, if length S [mm] / 100 [mm / s] = 0.02 [s], then S = 2 [mm], and the magnetic shielding member 403 has to be a slit for every 1 [mm]. Do n’t do that. Therefore, when the reproducibility of a one-dot image is taken into consideration at a resolution of 600 [dpi], the slits of the magnetic shielding member are arranged at intervals of 1 [mm] with a width of 1 [mm].

[Example 2]
Next, in the second embodiment, the configuration of the developing device 4 is almost the same as that of the first embodiment, but without using a magnetic shielding member, the linear velocity of rotation of the developer carrier 402 is changed to change the developing area. The two-component developer (hereinafter referred to as developer) is dynamically disturbed.
As described in the first embodiment, the developer is held and conveyed by the fixed magnet inside the sleeve of the developer carrier 402 and the friction coefficient of the sleeve surface. Here, in this embodiment, an inertial force is applied to the developer by intermittently changing the linear velocity of the developer carrier (sleeve) 402, and then a force is applied to the developer by applying a transport force again. Dynamic disturbance is generated.

  Also in this embodiment, as shown in FIG. 6 (or FIG. 7), in the case of a configuration having a plurality of developing main magnetic poles inside the developer carrier, it is opposed to between the magnetic poles of the plurality of developing main magnetic poles. The closest contact point between the image carrier 1 and the developer carrier 402 is set in the portion to be processed. By setting in this way, the restraining magnetic field at the closest point of the development area is reduced, so that the freedom of movement of the developer by intermittently changing the linear velocity of the developer carrier (sleeve) is improved. Therefore, the disturbance of the developer can be promoted.

Hereinafter, a specific description will be given with reference to FIG.
The developer carrier 402 has a sleeve linear velocity of 360 [mm / s], and temporally changes the amount of current to the motor used for driving. Specifically, the rotation is changed to 200 [mm / s] at 0.0001 [sec] with respect to 360 [mm / s]. Thereafter, the electric energy (current × time) is rapidly applied again at 0.01 [sec] to return to 360 [mm / s]. If this is performed at a period of 0.0002 [sec], the frequency becomes 5 [kHz], and dynamic disturbance can be generated in the developer. In addition, the change in the linear velocity in the above-described cycle (frequency) does not affect the minimum unit image, and image degradation such as banding can be suppressed.

  Further, in this embodiment, in addition to the above configuration, the average particle diameter and specific gravity of magnetic particles (carriers) used for the two-component developer are different. By changing not only the particle diameter of the magnetic particles but also the specific gravity, the actual mass difference relationship becomes larger than the particle diameter, and the effect on the disturbance of the developer layer is further increased. A material having a very high difference in specific gravity of 5.7 with respect to 3.5 is selected. Note that changing not only the particle diameter of the magnetic particles but also the specific gravity in this way can also be applied to the configuration of Example 1 described above, and the same effect can be obtained.

Furthermore, in this embodiment, the magnetic particles have elasticity by coating the surface of the magnetic particles with a material having elasticity. Specifically, it is possible to develop elasticity by including a rubber material in the coat layer. In addition, since acrylic resin, silicone resin, epoxy-modified silicone resin, and the like have sufficient elasticity by themselves, it is possible to develop elasticity by using these materials for the coating layer.
By using these coats as magnetic particles, the developer urged to the photoreceptor 1 at the time of development can be developed when it collides with the surface of the photoreceptor, and at the same time, the developer can be blown off from the surface of the photoreceptor by elasticity. As a result, a space is created at the return position, and another developer can be supplied to the space. As a result, the contact probability of the magnetic particles sufficiently covered with the toner to the photoreceptor can be increased. The developing ability is improved and the developing efficiency is increased. It should be noted that providing the magnetic particles with elasticity in this way can also be applied to the configuration of Example 1 described above, and the same effect can be obtained.

1, 1Y, 1C, 1M, 1Bk: photoconductor (image carrier)
2, 2Y, 2C, 2M, 2Bk: charging device 3, 21: writing device (latent image forming means)
4, 4Y, 4C, 4M, 4Bk: Development device 5: Transfer device 5Y, 5C, 5M, 5Bk: Primary transfer device 6, 6Y, 6C, 6M, 6Bk: Photoconductor cleaning device 403: Magnetic shielding member 402: Developer Carrier 407: Fixed magnet

Japanese Patent No. 3518191 JP 2007-102122 A

Claims (14)

A two-component developer is carried by a developer carrier, the developer carrier is brought close to an image carrier on which a latent image is formed in a development region, and a developer is applied by applying a development bias to the developer carrier. In a developing device that attaches to the image carrier and develops it to form a visible image,
The developer carrier is composed of a rotating non-magnetic cylindrical member, and has a plurality of magnets fixedly disposed therein.
A developing device comprising means for dynamically disturbing a developer layer on the developer carrying member in the development region. The developing device according to claim 1,
A developing device, wherein a magnetic shielding member is disposed on a surface side or an inner surface side of the developer carrying member, and the developer layer is dynamically disturbed in the developing region. The developing device according to claim 1,
A developing device characterized in that a magnetic force shielding member that can move independently is disposed on the inner surface side of the developer carrying member, and the developer layer is dynamically disturbed in the developing region. In the developing device according to claim 2 or 3,
2. The developing device according to claim 1, wherein a time for shielding the magnetic force by the magnetic force shielding member is shorter than a time for moving one dot line width with respect to a linear velocity of the developer carrying member. The developing device according to claim 1,
A developing device characterized in that the developer layer is dynamically disturbed in the developing region by intermittently changing the linear velocity of the developer carrying member. The developing device according to claim 5,
2. A developing device according to claim 1, wherein a cycle of intermittently changing the linear velocity of the developer carrying member is shorter than a ratio of one dot line width to the linear velocity. In the developing device according to any one of claims 1 to 6,
When there are a plurality of developing main magnetic poles that generate a magnetic field in the developing region inside the developer carrying member, they face the magnetic poles of the plurality of developing main magnetic poles arranged inside the developer carrying member. A developing device characterized in that a closest contact point between the image carrier and the developer carrier is set in a portion. In the developing device according to any one of claims 1 to 7,
A developing device using magnetic particles having at least two different average particle diameters as the developer. The developing device according to claim 8, wherein
A developing device, wherein at least two types of magnetic particles having different average particle diameters have different saturation magnetization amounts. The developing device according to claim 8, wherein
A developing device characterized in that at least two kinds of magnetic particles having different average particle diameters have different specific gravities. In the developing device according to any one of claims 1 to 10,
A developing device characterized in that the magnetic particles used have elasticity. A two-component developer is carried by a developer carrier, the developer carrier is brought close to an image carrier on which a latent image is formed in a development region, and a developer is applied by applying a development bias to the developer carrier. In the developing method of forming a visible image by attaching to the image carrier and developing,
Development is accelerated by using the developing device according to any one of claims 1 to 11 and dynamically disturbing a developer layer on the developer carrying member in the development region. Development method. An image carrier, means for forming a latent image on the image carrier, developing means for developing the latent image on the image carrier to make it visible, and a visible image on the image carrier as a transfer material In an image forming apparatus comprising means for transferring directly or via an intermediate transfer member, and means for fixing a visible image transferred to the transfer material,
An image forming apparatus comprising the developing device according to claim 1 as the developing unit. A latent image is formed on the image carrier, the latent image on the image carrier is developed and visualized, and then the developed image on the image carrier is transferred directly to a transfer material or via an intermediate transfer member. In the image forming method of fixing the visible image transferred to the transfer material to form an image,
An image forming method using the developing method according to claim 12 as a method of developing a latent image on the image carrier.

Images