JP2614084B2 - Image forming device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention forms a latent image on an image carrier such as an electrophotographic photosensitive member or an electrostatic recording dielectric, and visualizes the latent image with a developing device. More particularly, the present invention relates to an image forming apparatus such as an electrophotographic apparatus or an electrostatic recording apparatus, and more particularly to a developer carrying apparatus that carries and conveys a developer in a developer container from a developer container to a development area facing an image carrier. The present invention relates to an image forming apparatus having a developing device having a body.

2. Description of the Related Art Conventionally, an image in which a latent image is formed on an image carrier such as an electrophotographic photosensitive member or an electrostatic recording dielectric by an electrophotographic method or an electrostatic recording method, and the latent image is visualized by a developing device. As the forming apparatus, various developing apparatuses have been proposed, and currently, the developing apparatus shown in FIG. 1 is generally used.

Referring to FIG. 1, the developing device includes a developer container 1 for containing a developer and a developer in the developer container 1 from the developer container 1 to a developing area 2 facing the image carrier 100. And a developer carrying member 3 that carries and conveys the developer. The developer carrier 3 may have any structure, but is usually formed of a nonmagnetic material in the shape of a sleeve or an endless belt, and has a magnet 4 disposed therein. Aluminum or stainless steel is used as the nonmagnetic material, but stainless steel is used in image forming apparatuses that require durability.

Normally, when a developer carrier is manufactured from a stainless steel material, both ends of a stainless steel plate are welded and formed into an endless shape in the form of a sleeve or a belt in terms of manufacturing cost.

SUMMARY OF THE INVENTION As described above, the present inventors have developed an image forming apparatus having a developing device provided with an endless developer carrier formed by welding both ends of a stainless steel plate. In the course of research and experiments, it has been found that when an entire surface halftone (gray image) or an entire black image is obtained by such a device, image omission occurs at the pitch of the rotation cycle of the developer carrying member.

As a result of pursuing the cause of this development, the present inventors have found that the above-mentioned image omission has occurred at the welding seam of the developer carrying member. As a result of further research and experiments, the following was found. In other words, since the welding seam of the developer carrier receives high heat by arc welding, the structure of non-magnetic austenitic stainless steel is usually martensitic (magnetic).
And only the joint portion becomes magnetic, and as a result, the magnet arranged in the developer carrier is magnetized when the developer carrier is rotated, and the magnetic field distribution by the magnet in the development area is changed. Is disturbed. In this way, in the development area, the magnetic field is partially increased by the magnetization of the developer carrier, or the magnetic field is disturbed, whereby the columnar arrangement of the developer on the developer carrier along the magnetic field is disturbed, The development state and flight conditions of the developer on the image carrier change, making it difficult for the developer to fly on the image carrier, lowering the development efficiency, and causing an image to fall off only at the welding seam. This development is conspicuous in the entire halftone or black image, and the density contrast between the normal high-density image around the welded seam and the low-density part of the image-missing part becomes large. Observed as missing.

The present inventors have conducted research and experiments to solve the above problems, and as a result, the above problem was completely solved by reducing the ferrite content (magnetic portion) of the welded joint to 0.03% or less. I found that it could be solved. Further, such a developer carrier has a nickel equivalent (% Ni + 0.5 ×% Mn + 30%).
× (% C +% N + 0.3 ×% Cu) is 14 or more, chromium equivalent (% Cr + 1.5 ×% Si +% Mo + 0.5 ×% Nb) is 20 or less, and the chemical component% of molybdenum (Mo) is It has been found that this can be achieved by using an austenitic stainless steel having a chemical composition such as 0.1 or less.

Accordingly, an object of the present invention is to provide a stainless steel developer having a welded seam portion capable of obtaining a high-quality image without image whiteout even in a full-halftone or full-black image. An object of the present invention is to provide an image forming apparatus using a developing device having a body.

Means for Solving the Problems The above object is achieved by an image forming apparatus according to the present invention. In summary, the present invention provides an image carrier for carrying a latent image, and a developer carried from a developer container to a development area facing the image carrier for developing the latent image on the image carrier. And a developing device having a developer carrier for transferring and transporting, the developer carrier of the developing device contains chromium (Cr) as a main component, contains nickel (Ni), and has a nickel equivalent (% Ni + 0.5 ×% Mn + 30 ×% C + 30 ×% N + 0.3 ×%
Cu) is 14 or more and the chromium equivalent (% Cr + 1.5 ×% Si +
% Mo + 0.5 ×% Nb) is 20 or less, and molybdenum (Mo)
Is formed endless by welding both ends of an austenitic stainless steel sheet whose chemical component% is 0.1% or less, and the ferrite content of the welded joint of the austenitic stainless steel sheet is 0.03% or less. An image forming apparatus characterized in that:

Next, an image forming apparatus according to the present invention will be described in more detail with reference to the drawings.

FIG. 1 shows an embodiment of the image forming apparatus according to the present invention. In this embodiment, the image forming apparatus is an image bearing member such as a drum-shaped electrophotographic photosensitive member or a dielectric.
Has 100. An electrostatic latent image forming unit 5 is provided around the image carrier 100.
0, a developing device 40 for visualizing a latent image on the image carrier 100, a transfer separation unit 60 for transferring a visible toner image on the image carrier 100 to a transfer material, A cleaning unit 70 for cleaning the residual developer is provided. Latent image forming section
Since the transfer unit 60, the transfer unit 60, and the cleaning unit 70 are well known to those skilled in the art, further detailed description will be omitted.

The developing device 40 includes a developer container 1 for storing a developer.
And a developer carrier 3 that carries and conveys the developer in the developer container 1 from the developer container 1 to the development area 2 facing the image carrier 100. The developer carrier 3 is made of non-magnetic stainless steel and is formed in a sleeve shape in this embodiment, but may be formed in an endless belt shape, in which a magnet 4 is disposed.

Stirring means 5 and 6 are further provided in the developing container 1 to send the developer from the developer container 1 to the developer carrier 3 and to enhance the fluidity of the developer. Also, the developing device 40
The magnetic blade 7 for regulating the thickness of the developer layer on the developer carrier 3 together with the counter magnetic pole is disposed.

The developer conveyed from the inside of the developer container 1 to the developing area by the developer carrier 3 rises by the developing magnetic pole of the magnet 4, and is moved by the power supply 9 connected to the developer carrier 3 to the image carrier. Ten
0, an electrolysis formed between the latent image on
Preferably, the developer on the developer carrier 3 flies to the image carrier 100 by an alternating electric field such as AC to form a visible image.

According to the present invention, the developer carrier 3 is made of chromium (C
r) as a main component, formed by welding both ends of an austenitic stainless steel plate containing nickel (Ni), and the ferrite content of the welded seam of the austenitic stainless steel plate is 0.03% or less. Is done. Thus, the ferrite content of the welded seam was 0.03
%, The portion containing the properties as a magnetic material can be reduced to an extremely small amount so that the developing magnetic field is not affected at all.

According to the results of research experiments conducted by the present inventors, when the ferrite content in the welded joint portion exceeds 0.03%, the phenomenon of image omission appears in the case of full-halftone and full-black images, and in particular, the developer carrier 3 When the entire surface is halftone or black by using a magnetic toner having a volume average particle diameter of 4 to 11 μm, the image omission becomes remarkable. I understood.

More specifically, the austenitic stainless steel sheet for producing the developer carrier 3 according to the present invention has a nickel equivalent (% Ni + 0.5 ×% Mn + 30 ×% C + 30 ×% N + 0.3).
×% Cu) is 14 or more and the chromium equivalent (% Cr + 1.5 ×% S)
i +% Mo + 0.5 ×% Nb) is 20 or less, and molybdenum (M
A stainless steel material in which the chemical component% of o) is 0.1% or less is used. As such a stainless steel material, for example, nickel equivalent (% Ni + 0.5 ×% Mn + 30 × (% C +%
N) + 0.3 ×% Cu) is 15.2 and the chromium equivalent (% Cr +
1.5 ×% Si +% Mo + 0.5 ×% Nb) is 19.3, and austenitic stainless steel SUS305 having a molybdenum (Mo) chemical component% of 0.06 can be suitably used. For example,
Nickel equivalent is 12.4, chromium equivalent is 19.8,
Austenitic stainless steel SUS304 with molybdenum (Mo) chemical composition% of 0.15 and austenitic stainless steel SU with nickel equivalent of 13.3, chromium equivalent of 20.4 and molybdenum (Mo) chemical composition of 2.13
S316 etc. cannot be used.

In this specification,% in the metal composition means chemical component%.
Shall be shown.

According to the research experiments of the present inventors, the nickel equivalent is 14 or more and the chromium equivalent is 20 or less as described above,
An austenitic stainless steel material having a molybdenum (Mo) chemical component% of 0.1% or less is unlikely to change to a martensitic structure by heating. Therefore, when a stainless steel material having such a composition is used, the developer carrier It was also found that the welded seam maintained an austenitic structure even when welding was performed to produce the steel, and had a strong structure that was hard to be magnetic. Generally, the larger the nickel equivalent, the more stable the austenitic properties.

In the image forming apparatus having the structure shown in FIG. 1, a developer carrying member of the developing device was manufactured using austenitic stainless steel SUS305, and an image was obtained. Was done. In particular, there was no image whiteout in the rotation cycle of the developer carrying member in the entire surface halftone or black image, and extremely stable high-quality and copying was enabled.

In particular, the surface of the developer carrying member is formed into a plurality of concave shapes which are relatively smoothed by blasting, and have a volume average particle diameter of 4%.
Even when performing full-tone halftone and full-black image output using a magnetic toner having a small particle size of ~ 11 μm,
At the welding seam, there is no delicate disturbance or fluctuation of the developing magnetic field in the developing area and an excessive increase in the magnetic flux density on the developer carrier due to the magnetization of the welding seam. Fly at a certain efficiency to perform the developing action. Therefore, according to the present invention, it has been clarified that there is no decrease in the development efficiency at the welded seam portion and no image omission occurs.

The developer used in this example contains 17 to 60% by number of magnetic toner particles having a particle size of 5 μm or less, contains 1 to 23% by number of magnetic toner particles having a particle size of 8 to 12.7 μm, and has a particle size of 16 μm or more. The magnetic toner had a particle size distribution in which the volume average particle diameter of the magnetic toner was 4 to 11 μm.

The blasting conditions of the developer carrier are as follows: irregular blast abrasive grains (particles with a rough surface) are # 400 Al ₂ O ₃ , and regular blast abrasive grains (spherical or flat particles with a smooth surface) are used. # 400 glass beads are mixed at 1: 1 ratio and sprayed, nozzle diameter 7mm, distance 100mm, air pressure
Sandblasting was performed at 3 kg / m ² for about 1 to 2 minutes. Thereafter, the surface of the developer carrier was washed in a washing step and dried.

Observation of the surface of the developer carrier after the above-mentioned processing by an electron microscope reveals that, in the rotation direction of the developer carrier, that is, the developer transport direction, a fine rough surface area and a relatively smoothed concave area (this concave area has 0.2S, 0.8S, 1.6S, 0S, etc.) are alternately arranged.

The developer carrier is not blasted with a mixture of irregular blast abrasive grains and regular blast abrasive grains as described above. Instead, the regular blast abrasive grains (spheres having a smooth surface, or flat particles, hemispherical particles or Blasting can also be performed using abrasive grains of only particles having partially spherical surfaces, or amorphous blast abrasive grains having a rough surface (such as alumina Al ₂ O ₃ ).

In the above embodiment, the developer layer regulating member 7 is described as a rigid blade. However, a flexible blade member such as a urethane rubber sheet or a polyethylene terephthalate sheet is used as the developer layer regulating member, and the blade is used as a developer carrier. The same operation and effect as in the above-described embodiment can be obtained also in the developing device having a configuration in which the developing device is brought into contact with the developing device.

Effect of the Invention As described above, the image forming apparatus according to the present invention has
Change the material of the developer carrier to nickel equivalent (% Ni + 0.5 ×% Mn
+ 30 × (% C +% N) + 0.3 ×% Cu) is 14 or more, chromium equivalent (% Cr + 1.5 ×% Si +% Mo + 0.5 ×% Nb) is 20 or less,
In addition, it is made of austenitic stainless steel having a chemical component whose chemical component% of molybdenum (Mo) is 0.1 or less, and developed so that the ferrite content of the welded joint is 0.03% or less. Prevents the welding seam from becoming magnetic when forming the agent carrier into an endless shape, or reduces the magnetic material to ensure stable development efficiency without disturbing the developing magnetic field in the developing area in the developing device. There is an effect that the image can be prevented from being omitted during the rotation cycle of the developer carrying member and a high quality image can be obtained.

In particular, according to the image forming apparatus of the present invention, a fine magnetic toner having a volume average particle size of 4 to 11 μm is used as a developer, and a plurality of relatively smooth concave shapes are formed on the surface as a developer carrier. Even when a developer carrier is used, an image forming apparatus with high density, high image quality, and high durability can completely prevent image whiteout development in the rotation cycle of the developer carrier in the entire halftone and black images. Can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of an embodiment of the image forming apparatus according to the present invention. 3: Developer carrier 40: Developing device 100: Image carrier

Claims (1)

(57) [Claims] An image carrier for carrying a latent image, and a developer carried from a developer container to a development area facing the image carrier for developing the latent image on the image carrier. And an image forming apparatus having a developing device having a developer carrying member, wherein the developer carrying member of the developing device contains chromium (Cr) as a main component, contains nickel (Ni), and has a nickel equivalent (% Ni
+ 0.5 ×% Mn + 30 ×% C + 30 ×% N + 0.3 ×% Cu) is 14 or more and chromium equivalent (% Cr + 1.5 ×% Si +% Mo + 0.5 ×
% Nb) is 20 or less, and the chemical component% of molybdenum (Mo)
Is formed to be endless by welding both ends of an austenitic stainless steel sheet having an austenitic stainless steel sheet of 0.1% or less, and the ferrite content of the welded joint of the austenitic stainless steel sheet is 0.03% or less. Characteristic image forming apparatus.