JPH0475075A - Developing method - Google Patents

Abstract

PURPOSE:To obtain a high-density and high-definition image by making a developer carrying means flexible, providing the magnetic field generating means of a thin layer, and mixing a development improving agent with toner. CONSTITUTION:A developing device 7 carries a developer 8 that the development improving agent as a ferrite grain is mixed with the toner for actualizing an electrostatic latent image and carries out development. A developing roller 9 is formed in such a manner that a conductive elastic layer 11 and the magnetic field generating layer 12 are respectively disposed on a concentric circular on the outer periphery of a shaft 10. The developer 8 is directly held on the developing roll 9 by the leakage flux of the outer periphery of the magnetic field generating layer 12. The developer 8 of the thin layer formed by the rotation of the developing roller 9 in a state where the developer 8 is regulated to a proper quantity by a thin plate spring-like elastic blade 13, is carried. Therefore, the developing roller 9 can be in the state of press urized-contact with a latent image carrier 1, a developing nip is widened, and a developing electrode effect is also obtained. Thus, the development for the high-density and high-definition image can be carried out even at high speed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a developing method for developing an electrostatic latent image formed on a latent image carrier with a developer.

[Prior Art] As disclosed in Japanese Patent Application Laid-Open No. 58-49969, a conventional developing device divides a magnetic component developer at minute intervals in the circumferential direction to generate a magnetized magnetic field-generating thin layer. The image was transported and developed using a cylindrical drum.

[Problems to be Solved by the Invention] However, the above-mentioned developing method has the problem that it is difficult to press the developing roller against the latent image carrier and to widen the developing nip, resulting in insufficient amount of development. was. Further, it is difficult to bring the developing electrode on the developer transporting body side and the developing electrode on the latent image carrier side close to each other over a wide area, and there is also the problem that high-quality image development with the developing electrode effect cannot be achieved.

In addition, the amount of charge is insufficient due to insufficient agitation of the toner, and furthermore, when the toner is held and transported by magnetic force, the toner with an insufficient amount of charge is also transported to the development area, causing ground force blur. There was also a problem.

SUMMARY OF THE INVENTION The present invention is intended to solve these problems, and its purpose is to provide a developing method that can produce high-quality images with high hot water density. Another object of the present invention is to provide a developing method that enables high-quality development using a tJz type, lightweight, and low-cost developing device.

[Means for Solving the Problems] The developing method of the present invention is a developing method in which an electrostatic latent image on a latent image carrier is developed while a developer is transported by a developer transporting means. It is characterized in that it is flexible, has a thin layer of magnetic field generating means, and uses a developer in which a toner for visualizing a latent image is mixed with a development improver.

Further, the developing device of the present invention is characterized in that the development improver includes particles containing at least on the surface a substance that charges the toner to a predetermined polarity.

Further, the developing device of the present invention is characterized in that the development improver contains conductive particles.

[Function] According to the above structure of the present invention, since the magnetic thin layer is provided on the developer conveying body, it is possible to apply fine pitch magnetization to the magnetic thin layer, and furthermore, it is possible to apply fine pitch magnetization to the magnetic thin layer. The formed magnetic field extends only near the surface of the developer conveying body, and it is possible to easily form a thin layer of magnetic developer (or a thin layer of magnetic brushes with a fine pitch). In addition, since the thinned magnetic developer layer is transported by a flexible developer transporter, it can be brought into pressure contact with the latent image carrier, allowing a wide development nip and a development electrode effect. It is possible to develop high-quality images at 100%. Furthermore, by using particles containing at least a substance on the surface that charges the toner to a predetermined polarity or conductive particles as a development improver, the chargeability of the toner can be improved without the need for a special toner charging device. can be improved. Therefore, even when using magnetic toner, it is possible to supply toner with a stable and high charge amount to the developing area, preventing ground blurring, and developing high-quality images with a small, lightweight, and low-cost developing device. It is possible to provide a developing method that can be used.

Hereinafter, the present invention will be explained in detail with reference to Examples.

[Example 1] FIG. 1 is a cross-sectional schematic diagram of an image forming apparatus using the developing method of the present invention, in which a latent image carrier 1 is coated with an organic or inorganic photoconductive material on a conductive support 2. After the photosensitive layer 3 is charged using a charger 4 such as a corona charger or a charging roller, a laser or L
Light emitted from a light source 5 such as an ED is selectively irradiated onto the photosensitive layer 3 according to an image through an imaging optical system 6 to obtain a potential contrast and form an electrostatic latent image. On the other hand, the developing device 7 has a volume average particle path of 10 [μm] with magnetism that visualizes the electrostatic latent image.
The developer 8, which is a toner mixed with a development improver which is ferrite particles having a volume average particle path of 5[mu]m at a weight ratio of 0.2%, is transported for development. Developing roller 9
In this example, a conductive elastic layer 11 and a magnetic field generating layer 12 are arranged concentrically around the outer periphery of a shaft 10, and the developer 8 is directly held on the developing roller 9 by leakage magnetic flux on the outer periphery of the magnetic field generating layer 12. The developer 8 formed in a thin layer is conveyed by rotating the developing roller 9 while regulating the appropriate amount with a thin plate spring-like elastic blade 13 made of non-magnetic or magnetic metal or resin. By magnetizing the magnetic field generation layer 12 in the horizontal direction so that the magnetization reversal pitch is 100 [μm] or less, the developer 8 is placed on the magnetic field generation layer 12.
, a fine toner chain is formed and a thin and stable toner layer is obtained. When the developer 8 is conveyed to the development area where the latent image carrier 1 and the development roller 9 are in pressure contact,
Depending on the potential contrast of the latent image carrier 1 and the developing electric field formed by the developing bias applying means 14, the charged developer 8 adheres to the latent image carrier 1, and the electrostatic latent image is visualized. Furthermore, the toner image is transferred onto the recording paper 16 using a transfer device 15 such as a corona transfer device or a transfer roller,
The toner 8 is fixed on the recording paper using heat or pressure to obtain a desired image on the recording paper. When we continuously formed 10,000 sheets of 600 [DPI] line images, character images, and solid images using the image forming apparatus shown in Fig. 1, we found that the 600 [DPI] line images did not become thicker. It was possible to stably form a high-density solid image with an OD value of 1.4 or more without any trailing or blurring at the edges of the image.

FIG. 2 is a cross-sectional schematic diagram of an image forming apparatus in another embodiment using the developing method of the present invention, in which members having the same functions and names as those in FIG. 1 are given the same numbers and explained. omitted. The current (fJ device 21) is a magnetic toner with a volume average particle path of 10 [μm] that visualizes an electrostatic latent image, and ferrite particles with a volume average particle path of 50 [μm] coated with acrylic. A developer 22 mixed with a development improver at a weight ratio of 0.1% is conveyed and developed. It is composed of a cylindrical conductive thin film member 25 that is wrapped around the roller 24 and the drive roller 24 with an extra length left on the outer periphery, and a magnetic field generation layer 26 is disposed on the cylindrical thin film member 25 to generate a magnetic field. The developer 22 is held directly on the developing roller 23 by leakage magnetic flux around the outer periphery of the layer 26,
A thin layer of developer 22 is conveyed by rotating the developing roller 9 while regulating the appropriate amount with a thin plate spring-like elastic blade 13 made of non-magnetic or magnetic metal or resin. The magnetic field generation layer 26 has a magnetization reversal pitch of 100 μml.
By magnetizing in the horizontal direction as shown below, a minute toner chain is formed by the developer 22 on the magnetic field generating layer 26, and a thin and stable toner layer is obtained. When the developer 22 is conveyed to the development area where the latent image carrier 1 and the developing roller 23 are in pressure contact, the developer 22 is transferred according to the potential contrast of the latent image carrier 1 and the development electric field formed by the development bias applying means 14. , the charged developer 22 adheres to the latent image carrier 1, and the electrostatic latent image is visualized. 600 [DPI] using an image forming apparatus as shown in FIG.
1000 line images, character images and solid images
When 0 sheets were continuously formed, the result was 600 [DPI]
Line images are stably formed without line thickening,
It was possible to stably form a high-density solid image with an OD value of 1.4 or more without any trailing or blurring at the edges of the image.

FIG. 3 is a cross-sectional schematic diagram of an image forming apparatus in still another practical example using the developing method of the present invention, in which members having the same names and functions as those in FIG. 1 are given the same numbers. The explanation will be omitted. The developing device 31 conveys and develops the developer 22, and includes a developer conveying belt 3 that conveys the developer 22.
2 is corrugated on the outer periphery of the guide roller 33,
A magnetic field generating layer 35 is provided on a conductive layer 34 which is a base. The developer M conveyor belt 32 holds the developer 22 by leakage magnetic flux around the outer periphery of the magnetic field generation layer 35, and regulates the amount of developer 22 to an appropriate amount with a thin plate spring-like elastic blade 13 made of non-magnetic or magnetic metal or resin. It conveys a thin layer of developer 22. The magnetic field generation layer 35 has a magnetization reversal pitch of 100 μm.
By magnetizing in the horizontal direction so that the magnetic field is less than 1, a minute toner chain is formed by the developer 22 on the magnetic field generating layer 35, and a thin and stable toner layer is obtained. When the developer 22 is conveyed to the developing area where the developer conveying belt 32 is in pressure contact with the latent image carrier 1, the developer 22 is transferred according to the potential contrast of the latent image carrier 1 and the developing electric field formed by the developing bias applying means 14. The charged toner adheres to the latent image carrier l, and the electrostatic latent image is visualized. Using an image forming apparatus as shown in Fig. 3, line images, character images, and solid images of 600 [DPI] are
When continuously formed over several sheets, a line image of 600 [DPI] was stably formed without line thickening, and there was no tailing or blurring at the edge of the image, and a high-density solid image with an OD value of 1.4 or more. could be formed stably.

In FIGS. 1 to 3, the magnetic field generation layer can be made of a known magnetic recording material or magnet material, and more specifically, at least one element selected from Fe, Ni, Co, and Mn. A magnetic material containing, for example, γ
-Fe2Q3, Ba-Fe, Ni-Co, Co-Cr,
Mn-Al etc. can be used, and the film thickness is 100 [μ
m] or less, preferably around 10 [μm1], and the minimum magnetization reversal pitch is 100 [μm] or less to make the developer a uniformly thin layer. At the same time, the amount of toner conveyed on the developer conveyance belt by magnetic brush formation Density unevenness can be reduced by suppressing fluctuations to minute pitches. Further, it is also possible to use a perpendicular magnetization film as the magnetic field generation layer. Further, as the toner used in the present invention, all toners known as developers can be used, including resin-based toners such as styrene acrylic or polyester, and wax-based toners. Furthermore, the present invention can be applied regardless of whether the toner has positive or negative charging polarity. Further, as the development improver, magnetic powder itself such as ferrite or iron, or a material whose surface is coated with a substance that charges the toner to a desired polarity, such as acrylic, or resin particles such as acrylic or polyester may also be used. I can do it.

In addition, the particle size of the development improver is preferably 5° [μm] or less when the development improver is conveyed to the development area as in the above example, but this is not shown in the example. However, in cases where the development improver remains in the developer container and is not transported to the development area, the volume average particle diameter is 50 [μ
m1 or more, and even 1000 [μm1 or more may be used. Furthermore, even if the mixing weight ratio of the development improver to the toner is less than 1% as in the above embodiment, the effect of improving the charging property of the toner can be obtained, but if the development improver is not conveyed to the development area or When the developer transporting means is coated with a development improver, the same effect can be obtained even if the mixing weight ratio is increased to 90% or more.

In addition, in FIGS. 1 to 3, the present invention is not limited only to the configurations shown in the figures, and the arrows indicate the rotation directions of the respective members, but the present invention is not limited to the structures shown in the figures. Furthermore, the developing device can be used regardless of whether it is for regular development or reversal development.

FIG. 4 is a diagram showing the toner charge 1 distribution in an example of the developing method of the present invention. The developer A is composed only of a magnetic toner having a volume average particle diameter of 9 [μm] containing 50 [wt%] of magnetite in a styrene-acrylic binder. Developer B is a developer in which ferrite particles having a volume average particle diameter of 50 [μm] are mixed as a development improver in the same toner as developer A at a weight ratio of 0.5 [wt%].

Developer C is a developer in which particles of acrylic coated ferrite having a volume average particle size of 50 [μm] are mixed as a developer in the same toner as Developer A at a weight ratio of 0.5 [wt%]. FIG. 4 shows the charge amount distribution of each developer after stirring developer A, developer B, and developer C for 15 minutes in a ball mill. From Figure 4, development MA
It is clear from this that the charge amount distribution of developer B and developer C has shifted to the high charge side, and the proportion of toner charged to the opposite polarity has decreased. Furthermore, when we compared the images formed by the image forming apparatus of Example 1 using developer A, developer B, and developer C, we found that compared to developer A,
Developers B and C provided images with high density and less blurring.

Although the embodiments have been described above, the present invention can be applied not only to the above embodiments but also to a wide range of developing devices such as electrophotography.
It is especially effective when applied to printers, copiers, facsimiles, and displays.

[Effects of the Invention] As described above, according to the present invention, since a thin magnetic field generating layer that can be magnetized at a minute pitch is used, it is possible to easily form a thin layer of magnetic developer. , since the thinner developer layer is transported by a flexible developer transporter,
The developer conveying member can be brought into pressure contact with the latent image carrier, the development nip can be widened, a development electrode effect can be obtained, and development with high density and high image quality is possible even at high speeds.

Further, a development improver containing at least on the surface a substance that imparts a predetermined polar charge to the toner, or
By mixing a conductive development improver, toner charging properties can be improved with a simple configuration without the need for a toner charging device. It also has the effect of being able to develop more stable and high quality images without blurring.

Therefore, the developing method of the present invention has the excellent effect of providing a developing method that can produce high-resolution images with fewer image defects such as blurring and trailing.

[BRIEF DESCRIPTION OF THE DRAWINGS] FIG. 1 is a cross-sectional overview of an image forming apparatus using the developing method of the present invention, and FIG. 2 is a cross-sectional overview of an image forming apparatus in another embodiment using the developing method of the present invention. 3 is a cross-sectional schematic view of an image forming apparatus in still another embodiment using the developing method of the present invention, and FIG. 4 is a diagram showing the toner charge amount distribution of the embodiment in the developing method of the present invention. It is. 8, 22 9.23 1 2.26.35 Latent image carrier developing device Developer conductive layer Developing roller Magnetic field generating layer Diagram: Conductive layer: Developer transport belt Applicant Seiko Epson Corporation Agent Patent attorney Kizo Suzuki Department (1 person) Figure 2

Claims (3)

[Claims] (1) In a developing method in which an electrostatic latent image on a latent image carrier is developed while a developer is transported by a developer transport means, the developer transport means is flexible and includes a thin layer of magnetic field generating means. 1. A developing method characterized by using the above-mentioned developer in which a development improver is mixed with a toner that has a latent image and visualizes a latent image. (2) The developing method according to item 1, wherein the development improver includes particles containing at least on the surface a substance that charges the toner to a predetermined polarity. (3) The developing method according to item 1 or 2, wherein the development improver contains conductive particles.