JPS5857165A - Developing device - Google Patents

Abstract

PURPOSE:To improve the toner carriability and stabilize the uniform coating and make the surface hard, by subjecting the surface of a developer supporting member to the alumite treatment and subjecting it to the sand blast treatment with fixed-form grains to form a rugged rough surface. CONSTITUTION:A sleeve 2 as a developer supporting member having a magnetic field generating means internally consists of aluminum, and a hard alumite layer 2a having a thickness of 5-50mu is formed on the surface by the anodic oxidation in a sulfuric acid solution, and the surface of the sleeve is subjected to the sand blast treatment with glass beads as fixed-form (ball-shaped) blast abrasive grains to form a rough surface having a ruggedness pitch of 2-50mu and an average roughness (d) of 0.1-8mu. As fixed-form grains, steel balls and ferrit balls are used besides glass beads.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a dry developing device that is applied to image forming equipment such as copying machines and information recording devices. More specifically, the present invention relates to a developing device in which the surface of a developer support member is subjected to roughening and hardening treatment to improve its quality.

Conventionally, as a developing method using a component magnetic toner, a developing method using a conductive magnetic toner disclosed in U.S. Patent No. 3.909.258 is known.
It is also widely used. However, in such a developing method, it is necessary that the toner is inherently conductive, and the conductive toner is capable of forming the toner image on the latent image holding member in the final image.
It was difficult to transfer images onto a supporting member (for example, plain paper) using an electric field. Therefore, the applicant of the present application first solved this drawback of the conventional developing method using one-component magnetic toner. proposed a new developing method (for example, Japanese Patent Laid-Open Nos. 55-18656 and 55-1865);
-18659 etc.). In this method, an insulating magnetic toner is uniformly applied onto a cylindrical developer support member having a magnet inside, and the toner is developed by facing the latent image holding member without contacting it. At this time, a low frequency alternating voltage is applied between the developer support member and the base conductor of the latent image holding member to cause the toner to reciprocate at the threshold between the developer support member and the latent image holding member. It is possible to perform good development without background capri, excellent gradation reproduction, and no thinning at the edges of the picture chamber. In this developing method, the toner is an insulator and can be easily transferred.

In such a developing method, it is extremely important to uniformly apply the toner onto the developer cartridge support member. In other words, if the toner layer on the developer support member becomes excessively thick, not only will the toner be rubbed against the latent image holding member, but also the toner will likely become insufficiently triboelectrically charged due to friction with the developer support member. When the toner image becomes faint,
Since the amount of toner provided for development is insufficient, the density of the image becomes unsatisfactory.

One method for forming a uniform layer of toner on the developer support member is to use a coating blade at the outlet of the toner container as shown in FIGS. 1 and 2.

In the device shown in FIG. 1, an elastic blade 1 made of rubber or the like is pressed against a developer support member 2, thereby regulating the thickness of toner 113.

@2 The one shown in Figure 2 has a stationary magnet 4 inscribed in the developer support member 2 with a tip 3 facing one magnetic pole N1 standing up and cutting it with the edge of the tip of the blade to reduce the effect of magnetic force. It is used to regulate the thickness of the toner layer (
For example, see %Kokai No. 54-43037).

By using these methods, it has become possible to lay a layer 3 of toner on the developer support member 2 with a uniformity of %. However, it has been experimentally discovered that it is difficult to stably form a uniform layer of toner on the developer supporting member over a long period of time in practice.

In particular, when a toner with significantly poor fluidity is used, or when a toner that causes agglomeration is used, it tends to be more difficult to form a uniform layer of toner. If there is any unevenness in the thickness of the toner on the developer support member 2 (hereinafter referred to as a sleeve), it will cause unevenness in the developed image, making it impossible to expect good WJfull.

As a very effective method to prevent unevenness.

The applicant proposed a new developing device (% Application No. 16453/1983). This is to prevent uneven coating by providing unevenness on the sleeve surface along the direction of movement.

The reason why the unevenness of the sleeve surface along the direction of movement is effective against unevenness is that the frictional force between the sleeve surface and the toner increases, making it difficult for slips to occur and stabilizing the force of pushing out the toner from the blade. This is thought to be due to the fact that periodic microvibrations were applied to the toner reservoir upstream of the blade due to the irregularities in the circumferential direction of the sleeve, loosening the toner lumps and making the toner smooth.

For example, as the above-mentioned sleeve, stainless steel (SUIL3
04) Image printing durability was carried out using a surface roughened sleeve sandblasted with irregularly shaped particles of $600 (7) particle size on x-leap.

No unevenness occurred.

However, when images were continuously produced using this developing device, the following phenomenon occurred.

(1) After making 300 to 500 copies of an original with a lot of white background, which requires extremely low toner consumption, the density of the art world was 1.
It decreased from 1 to 0.9.

(2) When black background copying (full darkness black) was continuously performed using a developing device with reduced image gR sharpness, the image density began to recover to 1.1 from the 9th point on the %30 to 50 sheet series.

(3) In addition, toner fusion occurred on the sleeve in dots and lines extending in the local direction. This was particularly noticeable when a pressure fixing toner was used.

(4) After continuous copying of tens of thousands of ordinary originals, some unevenness occurred, although this did not cause any practical problems.

Therefore, first, we measured the particle size of the toner on the surface of the sleeve when the image density decreased in (1) above, and found that the toner with a particle size of 1 to 5 μm was the main substance, and the toner in the hopper (average particle size of 8 to 5 μm) was found.
It was found that the particle size was clearly smaller than that of the toner (13μ), and that this change in toner particle size caused a change in density. This is because when toner is given an electric charge by friction with the sleeve, it is attracted onto the lj-spray by reflection force, but at this time, minute toner (1 to 5μ) is smaller than average (8 to 13μ) toner. This is because the suction force is so strong that minute toner particles are coated on the surface of the sleeve. For this reason, toner of 5 μm or more, which contributes most to development, does not have sufficient friction with the sleeve and is not charged. From this, it has been found that in order to suppress the sleeve coating due to the mirroring force of zero minute toner, which causes the image density to gradually decrease, it is advisable to make the sleeve surface insulating.

Furthermore, when the toner fusion in (3) was observed using a scanning electron microscope, it was found that the toner was fused in a manner that it was rubbed onto the countless minute protrusions on the sleeve surface.

Further, when the unevenness on the sleeve in (4) was examined, it was found that the unevenness on the sleeve surface was worn out due to long-term rotation, and it was found that some unevenness was caused by the wear. This rubs. It turned out to be good.

The object of the present invention is to eliminate the above-mentioned conventional drawbacks.

It is an object of the present invention to provide a developing device which is improved so that a thin layer of developer can always be coated stably, uniformly and without unevenness on the surface of a developer support member.

The present invention that achieves this objective is to apply a one-component magnetic developer by means of a developer thickness regulating member onto a developer support member having a magnetic field generating means therein, and to apply the one-component magnetic developer to a developer support member that faces a latent holding member. In this developing device, the surface of the developer supporting member is subjected to alkali treatment, and then subjected to sandblasting treatment using regular particles to form an uneven rough surface. Providing fine irregularities on the surface of the developer supporting member in this way improves the toner transportability and prevents changes in the one-box density due to changes in the stability of the uniform coating. Prevents wear on the support member surface and toner adhesion.

The purpose is to provide a modern device that is stable over a long period of time and can exhibit high performance.

Embodiments of the present invention will be described below in detail based on the drawings.0 [Embodiment Row 1] The developing device shown in Figure $J3 was used in this embodiment. Components that are the same as in FIG. 2 are designated by the same numbers. The strength of the magnetic pole of the magnet roll 4 is Nr = 82
0 gaums, 81 = g2Qgs+uss t
N2 = 8z = Na = 8g = 500 gaus
s + gap between sleeve 2 and drum 5 0.25111
1. The gap between the sleeve 2 and the blade 1 was maintained at 0.2 mm. Also, as a bias electric JJI6, ACK D
Vpp (piece-to-heat) = 1300V, f = 1000H.

I) Perform jumping current calculation with c = + 1oo(v).

The sleeve 2 is made of aluminum, and its surface is coated with approximately 30μ of aluminium by anodizing in a sulfuric acid solution.
After that, a glass piece of φ800 is used as regular (spherical) blast abrasive grains on the sleeve surface, and the nozzle diameter is set to 7. Distance 1100111E.

The material used was one that had been sandblasted at an air pressure of 4 and 47 cd for about 120 seconds. Steel balls as regular particles.

Ferrite spheres may also be used. When the latent surface was actually developed using the developing device configured as described above, the toner coating on the sleeve surface was very good, with no uneven coating. Furthermore, no toner fusion occurred on the sleeve.

Further, when 50,000 sheets were printed using the sleeve, good quality was always obtained and there was no decrease in image density. Also, 5
Even after passing 10,000 sheets of paper, the surface roughness of 0.7μ at the start remained unchanged at 0.7/1, and the sleeve was not worn at all and no unevenness occurred. This is because an alumite layer is formed on the sleeve surface to insulate the surface, thereby preventing a decrease in the density of the art.

After the alumite treatment, the blasting process is performed using regular, spherical particles, so that the final unevenness on the sleeve surface has no sharp protrusions and the shape is rounded, preventing the toner from being rubbed and melting. This is because it no longer causes wear and tear. Furthermore, the sleeve is hardened by alumite treatment and wear does not occur. That is, if this embodiment is used, the above-mentioned conventional problems can be solved.

[Example 2] Using the apparatus of the embodiment shown in FIG. 3, the alumite-treated sleeve was coated with various abrasive grain sizes.

Blast processing is performed by changing air pressure.

9. Experiments were conducted with the surface roughness on the sleeve ranging from 0.05 to 10μ. As a result, if the roughness is less than 0.1μ, the toner may slip on the sleeve and the toner may not be coated uniformly, resulting in uneven coating. Moreover, if it is 8 μ or more, no unevenness occurs at all, and the surface of the sleeve is too rough and the toner does not slip on the sleeve, but the toner gets into the concave part on the sleeve and there is insufficient friction with the sleeve. No electric charge was applied to the toner, the toner's developing ability was lost, and only a low-density image could be obtained. Moreover, the particularly effective surface roughness ao was 3 to 3.0μ, and the pitch of the unevenness was 5 to 30μ.

Next, in this example, an additional 500nr was applied with the toner added.
After m idle rotation, ij1 made an appearance.

A very good image was obtained. Moreover, when the surface was observed using a scanning electron microscope, the shape remained the same as the initial one, with no signs of wear at all.

[Example 3] Using the apparatus of the above example, an experiment was conducted by varying the thickness of the alumite layer and then performing blasting. As a result, when the thickness of the alumite is less than 5μ, it is difficult to perform blasting treatment.
Sufficient blasting was not done due to the influence of the aluminum base. Moreover, if the thickness is 50 μm or more, the electric field between the electrostatic holding surface and the sleeve surface is significantly reduced, and the developing action is suppressed from the beginning, resulting in a thinner image. Therefore, it is effective for the alumite layer to have a thickness of 5 to 50 μm. Furthermore, when forming the alumite layer of 50 sides.

Since precision may not be maintained by alumite treatment, in this example, alumite 1 was formed to a thickness of about 100β and then polished to form an alumite layer of 50μ.

Furthermore, it has been found that wear of the sleeve can be more reliably suppressed by using hard alumite as the alumite. In the developing device configuration considered in this experiment, ◆ Particularly good results were obtained when abrasive grains of 300 to φ800 were used. In the above experiment, 70 parts of magnetic powder was A pressure fixing toner containing 2 parts of charge control agent and 1 ts of silica was used. Incidentally, the average particle size of the magnetic toner used is 5 to 30
μ is preferably 5 to 15 μ.

Furthermore, as in the developing device shown in FIG.
In a device that develops by applying an alternating voltage V between the sleeve 2 and drum 5 and moving the toner back and forth between the sleeve 2 and drum 5, the surface roughness This is because the alternating electric field applied between the 4μ-pump 2 and the drum 5 concentrates on the convex portion, and the toner is attracted to the side where the electric field is stronger. Therefore, when the present invention is fully applied to the above-mentioned surface roughening method, it is preferable to set the surface roughness dtO to 1 to 4μ.

In addition, since the above-mentioned sleeve has random irregularities formed over the entire area, it is difficult to express the surface roughness unambiguously.
Alternatively, when measuring with a micro surface roughness meter sold by Koita Research Institute, etc., a waveform as shown in FIG. 4 is obtained, and the percent fitability can be controlled. ! In Figure 4, the average roughness Rz=
= 1.5μ, pitch = 19μ.

Here, the surface roughness is JI81Q point average roughness Rx)
(JI8 BO601). In other words, as shown in Figure 5, it is a straight line parallel to the average line of the part extracted by the standard length 1 from the polar line of 1 cross section, and it is deep if it passes through the third summit from the highest (indicated by ■ in the figure). The distance between the two straight lines is expressed in micrometers (μm>), and the standard length is 4=Q, 25 asm.The pitch is 〇250 IJ4 was calculated as follows by counting the height of the convex part as 0.1 tone or higher with respect to the concave parts on both sides as one mountain, and the number of peaks within the standard length of 0.25M. /250 (fi) Number of peaks (/1) In the above embodiment, a stainless sleeve was used, but a non-magnetic sleeve such as an aluminum sleeve or a steel sleeve can be used.

As described above, in the present invention, the surface of the developer supporting member is subjected to alumite treatment and then sandblasted with regular particles to roughen the surface, thereby providing a developing device that can exhibit stable high performance over a long period of time. It will be done.

[Brief explanation of drawings]

Figures 1 and 2 are sectional views of a conventional moat device, Figure 3 is a sectional view of a current moat device to which an embodiment of the present invention is applied, and Figure 4 is a waveform of the roughness of the sleeve surface. FIG. 5 is an explanatory view of the definition of surface roughness and pitch. In the figure, 1... elastic blade 12...
Developer support member, 2m...Alumite pane, 3...
... Tona layer, 4... Fixed magnet. 5: Drum, 6: Bias power supply. Applicant Canon Co., Ltd. 14(2)

Claims (6)

[Claims] (1) Apply -component magnetic developer using a developer thickness regulating member onto a developer supporting member that has a magnetic field generating means inside, and develop the latent scratch by placing it opposite the latent scratch retaining member. In the device that does. performing alumite treatment and treatment on the surface of the developer supporting member;
2. The developing device according to claim 1, wherein the surface is roughened by sandblasting with regular particles. (2) Claim 1, characterized in that the surface roughness of the drug support member is a rough surface with an uneven pitch of 2 to 50μ and an average roughness d=0.1 to 8μ. The current 1 honey device described. (3) The developing device according to claim 6, wherein the alumite layer formed by the alumite treatment is made of hard alumite. (4) The developing device according to any one of claims 1 to 3, wherein the alumite layer formed by the alumite treatment has a thickness of 5 to 50 μm. (5) The developing device according to claim 4, wherein a thick alumite layer is formed by the alumite treatment, and then polished to a thickness of 5 to 50 μm. (6) The developing device according to claim 1, wherein the regular shaped particles are any one of glass beads, steel balls, and ferrite balls.