JPS60125853A - Production of developer carrying body - Google Patents

Abstract

PURPOSE:To obtain a carrying body adequate for a one-component high-resistance magnetic toner by forming a dielectric layer, dielectric adhesive agent layer and electrode layer embedded with conductive particles in said adhesive layer in the state of insulating electrically the particles from each other in this order on a cylindrical conductive base then subjecting the base to specific surface while working rotating the base. CONSTITUTION:After a dielectric layer 4 is formed on the surface of a cylindrical conductive base 1, a dielectric adhesive agent 2b is thinly provided on the layer 4 and conductive particles 2a of Cu, etc. are uniformly sprayed on the layer 2b to bring the particles 2a into contact with layer 4 so that the particles are electrically insulated from each other, thus forming the single particles layer. The particles 2a are coated with the adhesive agent 2b' similar to the adhesive agent 2b to form an electrode layer 2'. The adhesive agents 2b, 2b' of the layer 2 are thoroughly cured and thereafter the end face of a grindstone 10a of a surface working tool 10 rotated around the axis perpendicular to the axis of revolution of the base 1 is brought into contact with the surface of the electrode layer 2' to make the thickness of the layer 2 larger than the diameter of the particles 2a so that the exposed surface area of the particles 2a attains >=45% of the surface area of the layer 2. The copy having the substantial density of the line image is thus obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a method for manufacturing a developer carrier, and more particularly, to a method for manufacturing a developer carrier suitable for a developing device using -component high resistance magnetic toner. be.

BACKGROUND ART In electrostatic recording devices such as electrophotographic copying machines, facsimile machines, and printers, the development characteristics required of the development device are different depending on whether the document is a line image or a solid image. FIG. 1 is a graph showing the preferred development characteristics, with the horizontal axis representing original image density and the vertical axis representing copy image density.

In the figure, the solid line A is the development characteristic required for a solid image, and the broken line B
indicates the development characteristics required for line images. According to this, in the case of a line image (broken line B), a solid image (solid line A) is better than a solid image (solid line A).
) The rising slope is steeper than in the case of ). The reason for this is that if the original is a line image, the clarity of the image will be poor if the original image density is low, so it is necessary to compensate for this by increasing the copy image density. This is because if a copy image density corresponding to the image density is obtained, the image will be sufficiently clear.

By the way, the so-called edge effect has been conventionally used to increase the density of the copied image of this line image.

That is, the strength of the electric field at the edges of the electrostatic latent image is stronger than the strength of the electric field at the center of the image, resulting in a larger amount of toner adhering to the edges of the image, resulting in an edge effect. Therefore, in the case of a line image with a small image area, most of the latent image forming area corresponds to the edge and is subject to the edge effect, resulting in a high value of the density of the copied image.

However, this edge effect is sufficiently effective when using a two-component developer containing toner and carrier, but when using a one-component developer that does not contain carrier. had the disadvantage that an effective edge effect could not be obtained.

Therefore, the applicant of the present application has proposed a developing device equipped with a developer carrier having a unique configuration that makes it possible to obtain the above-mentioned suitable development characteristics even when using a -component type developer (
(Japanese Patent Application No. 185726/1982). As shown in FIG. 2, the developer carrier according to this proposal has a large number of hemispherical minute electrode particles 28 made of a conductive material on the outer peripheral surface of a cylindrical conductive support 1 in the circumferential direction and The electrode layer 2 is formed so as to be uniformly scattered in the width direction, and the individual electrode particles 2a are insulated from each other and held in an electrically floating state. Note that when a magnetic developer is used, a magnetic roller (not shown) is provided inside the support 1 3.

A suitable method for manufacturing such a developer carrier is to apply the adhesive 2b onto the conductive support 1, sprinkle the conductive particles 2a on top of it, and then perform the outer diameter machining using a lathe or the like. A method has been proposed in which the surface of the electrode layer 2 is made smooth and the electrode particles are shaved into a hemispherical shape to expose a portion thereof on the surface. In this case, in order to obtain the desired edge effect,
The ratio (area ratio) of the area exposed on the surface of the electrode particles 2a to the total surface area of the electrode layer 2 is set to a predetermined value or more, for example, 45%.
It is required to secure the above. Furthermore, in order to prevent the electrode particles 2a from detaching, it is also necessary to avoid removing more than half of the volume of each particle. In order to meet the above conditions,
For example, when the particle size of each electrode particle is about 74 to 104 μm, the electrode layer 2 may be formed so that the electrode thickness is 52 to 62 μm. Note that the electrode thickness refers to the thickness t2A of the excised particle 2A in the electrode layer thickness t2 direction, as shown in FIG. The reason is as follows.

Figure 3 shows the thickness t2A of the electrode particle 2a and its area ratio AR.
It is a graph diagram showing the relationship between. In FIG. 3, the curve α1 curve β and the curve γ correspond to the maximum electrode particle with a particle size of 104 μm, the electrode particle with an average particle size, and the particle size of 74 μm, respectively.
It shows each interval in the minimum electrode particle of the door. According to this, 45% is required to obtain suitable development characteristics.
In order to ensure the above area ratio AR, the minimum particle (curve γ
), the electrode thickness t2 is adjusted so that the area ratio A'R is 45% or more.
The maximum value of A may be set to 62 μm. In addition, in order to prevent particle detachment due to the anchor effect, the largest particle (curve α
) It is necessary to ensure a thickness t2A of 52p- or more, which is half of 52p-. Therefore, the permissible range of the thickness t2A of the electrode particles 2a is 52 to 62 threads.

However, when machining the outer diameter of the electrode layer using a turning method based on a shaft (processing axis) that supports the workpiece, such as a lathe,
It is difficult to suppress the fluctuation width of the layer thickness t2 of the electrode layer 2 to 10JIm or less, which is the allowable range width of the electrode thickness t2A, and therefore, it becomes difficult to keep the electrode thickness t2A within the above-mentioned allowable range. (see figure). That is, as shown in FIG. 4, since the conductive support 1 needs to be formed with a thin wall, it is difficult to process the spigot parts 1a at both ends with high precision. A clearance P is likely to occur between the two. When the clearance P occurs, it becomes difficult to align the central axis Go of the support 1 with the central axis C+ (processing axis) of the support T. As a result, if an eccentricity of Δd occurs between the central axis Go and the processing axis c1,
The fluctuation width VR of the electrode layer thickness t2 that occurs due to this is the maximum of the layer thickness t2.

If the minimum values are jMAX and tM+N, respectively, VR-tM
Ax-tM+N becomes 2·Δd. Therefore, in order to keep the electrode thickness t2A within the allowable width range of 10 μm, each electrode particle 2a must have its bottom surface at the same level H (see Figure 2).
Under the precondition that the machining axis C1 is aligned with
It is required to suppress the eccentricity Δd to less than half of that, 5 pt*. It is extremely difficult to satisfy such strict processing conditions, which increases the number of man-hours and ultimately increases costs.

Purpose The present invention has been made in view of the above points, and it is possible to easily create a developer carrier capable of exhibiting a desired edge effect and stably obtaining high image quality even with a one-component developer. The purpose is to provide a manufacturing method that allows for manufacturing.

Configuration Hereinafter, the configuration of the present invention will be explained in detail based on specific examples. As shown in FIGS. 16(a) and 16(b), the developer carrier manufactured by the manufacturing method of this example is produced by forming a dielectric layer 4 on a conductive support 1, and then forming an electrode. This is a developer carrier 11 configured by laminating layers 2.

Note that the dielectric layer 4 is provided to ensure a necessary dielectric area (dielectric thickness) on the conductive support 1 to prevent edge effects.

First, as shown in FIG. 5, the conductive support 1 is formed into a cylindrical shape. In this case, if the present invention is applied to an imaging device that uses a magnetic developer as a developer and supports it by magnetic force, the conductive support 1 is made of a thin non-magnetic material such as stainless steel.

Next, after degreasing the outer peripheral surface of the support 1, a dielectric coating made of a dielectric material is uniformly applied over the entire outer peripheral surface. Specifically, as shown in FIG. 5, for example, a cylindrical sheathed heater 6 with a heater 5 mounted therein is horizontally rotatably provided, and the support 1 formed as described above is fitted onto the sheathed heater 6 for support. While heating the support body 1 to around 180°C and rotating both substantially integrally at a predetermined speed, dielectric powder 4- is applied to the support body 1 using an electrostatic coating method using a static 11m1 gun 7.
Spray evenly on the outer surface. In this case, thermosetting resin powder such as epoxy resin powder is suitable as the dielectric powder 4'. A holding table (not shown) that can move the coating gun 7 back and forth at a constant speed parallel to the sheathed heater 6
etc., and the spraying operation can be repeated until the desired layer thickness of, for example, about 500 pm is reached.

Paint the spray! After completion of I, the support 1 is continued to be rotated for an appropriate period of time while being heated by the sheathed heater 6, and the dielectric coating film 4 is cured as shown in FIG. Thereby, the film thickness t4- of the dielectric coating film 4- becomes approximately uniform not only in the width direction but also in the circumferential direction. Note that the heating method for the support 1 is as follows:
A method of heating from the outside using a far-infrared heater or the like may also be used.

The surface of the deposited dielectric coating film 4- usually has many irregularities, but in order to keep the thickness of the electrode particles within the above-mentioned tolerance range, this surface must be smooth to some extent. required. Therefore, the applied dielectric coating II! 4
The surface is smoothed by machining the outer diameter using a lathe or the like, and a dielectric layer 4 having a layer thickness t4 of about 400 mm is formed as shown in FIG. Incidentally, it is also possible to carry out the main outer diameter machining using other tools such as a cylindrical grinder.

After forming the dielectric layer 4 by outer diameter processing, the surface of the dielectric layer 4 is cleaned, and then, as shown in FIG. Spray adhesive such as acrylic urethane evenly. As a result, adhesive 1 as shown in FIG.
1!2b is deposited, but its film thickness t2B is as follows: When the electrode particles 2a to be dispersed in the next step (see FIG. 10) are copper particles with a particle size of 74 to 104 μm, for example, A thickness of about 3 to 15 μm is suitable to ensure that the dispersed particles adhere to the surface of the dielectric layer 4. In this step as well, the intermediate product in which the dielectric layer 4 is adhered and formed on the support 1, which is the workpiece (hereinafter referred to as work W), is coated with an appropriate coating as in the case of forming the dielectric coating film. If the adhesive film 2b is supported horizontally while being rotated at a high speed, and the above-described adhesive is repeatedly applied along this direction, the adhesive film 2b having a substantially uniform thickness can be easily formed. can.

Once the adhesive has been applied, and before it hardens, a large number of electrode particles are deposited substantially evenly on the surface of the dielectric layer.

For this attachment method, for example, as shown in FIG. 10, a large number of copper particles having a particle size of 74 to 104 pm are stored as electrode particles 2a in a tray 9 equipped with a dispersion port 9a, and then supported horizontally. The tray 9 is placed along the workpiece W that is rotated.
While reciprocating at an appropriate speed, tilt the
Electrode particles 2a are dropped little by little from a to form an adhesive film 2b.
Just sprinkle it on top and distribute it evenly. As a result, as shown in FIG. 11, each electrode particle 2a is attached substantially uniformly to the surface of the dielectric layer 4 while being in contact with the surface. In this example, each electrode particle 2a to be attached is coated in advance with a dielectric material such as styrene butyl acrylate, so even if it is scattered randomly by gravity, the individual electrode particles 2a can be reliably covered with the surrounding area. It can be attached in an insulating state (floating state) to the surface of the substrate. Further, the thickness of the adhesive film 2b is 3 to 15 μm...
Because it is so thin, the dispersed copper particles 2a with particle diameters of 74 to 104 μm are suspended! The resulting buoyancy is not generated, and each particle 2a naturally sinks to the surface of the dielectric layer 4. Therefore,
As shown in FIG. 11, the bottom surface of each electrode particle 2a can be easily and reliably aligned with the surface of the dielectric R4 simply by allowing the individual electrode particles 2a to fall naturally. In this example, copper particles are used as the electrode particles 2a, but the electrode particles 2a are not limited to this, and particles of other conductive materials such as brass, phosphor bronze, or stainless steel can also be used.

Next, after drying and curing the adhesive 2b almost completely,
As shown in the figure, the dielectric adhesive 2b- is again thickly coated (overcoated) on the electrode particles 2a and adhesive 2b in the same manner as the previous time. In this case, if the same adhesive as the previous one is used, the two will surely adhere to each other and the electrode particles 2a will be more firmly fixed in contact with the surface of the dielectric layer 4, which is advantageous in terms of durability. be. However, particles 2 adhere to each other
As long as a can be reliably fixed, combinations of dielectric adhesives made of different materials are also possible. In this way, by applying the adhesive in two steps with a drying process in between, re-melting of the previously applied adhesive 2b is avoided, so each electrode particle 2a is not suspended and the dielectric N4 surface is The particles 2a can be firmly fixed in a submerged state, and the prerequisite for keeping the electrode thickness within a predetermined tolerance range, which is to arrange the bottom surfaces of each particle 2a at the same level, can be easily achieved.

After applying a thick coat of adhesive, let it dry and harden. In this case, as shown in FIG. 13, if the workpiece W is inserted into the sheathed heater 6 and horizontally supported and rotated as well as heated and dried as in the case of forming the M electric layer, the thickly applied adhesive 2b= The adhesive 2 is laminated on the dielectric layer 4 without dripping.
b. The layer thickness t2- of the electrode layer 2- (a state before a part of each particle 2a is exposed to the surface), which is a combination of the electrode particles 2a and the thickly coated adhesive 2b-, becomes uniform. In this way, for example, the electrode layer 2- with a layer thickness t2- of about 150 pm is formed.

Then, as shown in FIG. 14, the electrode layer 2'
The surface of the electrode layer 2 is finished by processing the outer diameter of the electrode layer 2 to make the surface smooth and to expose a portion of each electrode particle 2a to the surface. By the way, in the method of the present invention, since each electrode particle 2a is fixed in contact with the surface of the dielectric layer 4, the layer thickness t2 of the finished electrode layer 2 is equal to the electrode thickness t2A. Therefore, if the layer thickness °C2 of the electrode layer 2 is kept within the allowable range of the electrode thickness t2A of 52 to 62 μm, the electrode particles 2
The exposed area ratio AR of a is ensured to be 45% or more, and the particle 2
A desired electrode layer 2 in which a is difficult to separate from 12 can be obtained.

Therefore, in the method of the present invention, the main outer diameter machining step is carried out by a surface machining method using the outer circumferential surface S of the workpiece W (the surface of the electrode layer 2') as a reference.

In this example, as shown in FIG. 15(a), the support 1
A grindstone 10d as a surface processing tool is attached to the tip of a bar 10c rotatably supported on the shaft 10b via a shaft 10b.
A grinding device 10 is used. The whetstone 10d is
As shown in FIG. 15(b), it is formed into a bowl shape, and when it is reversed, it has an axis C perpendicular to the rotation axis Cw of the workpiece W.
e, and the side end surface 10dl is brought into contact with the circumferential surface of the workpiece W, which is rotated at a predetermined speed and centered around the rotation axis Cw, for grinding. Rotation axis CB of grindstone 10d
The other end is connected to a drive motor 10f via a belt 10e. Further, a weight 10o is attached to the other end of the bar 10c, and an adjustment weight 10h is provided so as to be movable along the longitudinal direction of the bar 100.
By moving 0h appropriately, the grindstone 10d is moved to the workpiece W.
The pressure applied to the surface can be adjusted. Furthermore,
In order to move the grindstone 10d along the axial direction of the workpiece W, the entire grinding device 10 is configured to be movable in parallel to the axial direction of the workpiece W. Then, as shown in FIG. 15(c), the support 10a is attached to the tool post (not shown) of the lathe, and the workpiece W is set on the main shaft A of the lathe and rotated about the longitudinal axis, and the circumferential surface The grindstone 10d is rotated around the rotation axis CB and moved together with the tool rest in the longitudinal axis direction of the arrow while pressing against it, thereby uniformly grinding the entire circumferential surface.

If the grinding process is carried out in this way, the desired grinding process as shown in FIGS. An electrode layer 2 having a layer thickness of 52 to 62 IIm is formed. That is, FIG. 17(a), FIG. 17(b)
As shown in the figure, the support axis CA on which the main axis of the lathe supports the workpiece W is eccentric by Δd from the central axis Cw of the workpiece W (in this example, strictly speaking, the machining axis when machining the outer diameter of the dielectric layer 4). Then, the fluctuation range of the level H of the outer circumferential surface of the workpiece W rotated around the support shaft OA in contact with the grinding wheel 10d is twice as large as 2.
・It becomes Δd. However, the rotatably supported bar 10
0 rotates according to this variation, and whether the outer peripheral surface level H with respect to the grinding wheel 10d shown in FIG. 17(a) is the lowest, or the outer peripheral surface level H shown in FIG. 17(11) is the highest. , the pressure of the grindstone 10d in contact with the outer circumferential surface of the workpiece W is approximately constant. Therefore, in FIG. 14, the thickness t2R of the portion to be ground is made uniform over the entire circumferential surface, with the initial surface S of the electrode layer 2' of the workpiece W (the surface before grinding) being used as a reference. In this example, the electrode layer 2- has a layer thickness t2'' of 1
Since it is formed to have a substantially uniform thickness of 50 μm, the grinding process may be performed so that the grinding thickness t2R is 88 to 98 μm over the entire circumferential surface. In this case, as shown in FIG. 18, the machining axis C4 of the outer diameter machining when forming the dielectric layer 4 is
Even if the layer thickness of the dielectric layer 4 becomes uneven due to deviation from the central axis CO of Can be done.

In addition, since the area where the processed surface (end surface 10d1) of the grinding wheel 10d and the circumferential surface of the workpiece W come into contact is small, the processed surface used for grinding separates from the circumferential surface of the workpiece in a short period of time, so that the grinding debris is quickly transferred to the processed part. This prevents clogging of the processing surface of the grindstone 10d. Therefore, the occurrence of scratches on the circumferential surface of the workpiece W due to clogging of the machined surface is eliminated.

By processing the outer diameter of the electrode layer surface using the outer peripheral surface as a reference as described above, the layer thickness t2, that is, the electrode thickness t2A, is 52 to 62 mm as shown in FIGS. 16(a) and 16(11).
The electrode layer 2 whose pm is reliably kept within the permissible range is uniformly formed over the entire circumferential surface. Thereafter, by cleaning the surface of the dirt from the abrasive material, etc., the developer carrier 11 as a final product is completed.

In the above embodiment, the process of applying the adhesive is divided into two processes, but it may be divided into one process or three or more processes as necessary. In addition, the material of the dielectric layer 4 and the adhesive 2b
It is also possible to use the same or the same type of dielectric material. Furthermore, the material for the dielectric layer 4 is not limited to thermosetting resins, but also thermoplastic resins such as polyimide and ABS can be used.

Effects As detailed above, according to the present invention, the surface processing for finishing the electrode layer, which determines the electrode thickness, is performed based on the surface of the electrode layer, thereby improving the processing axis when forming the electrode layer, which requires precision. settings are not required. Therefore, a developer carrier having a desired electrode thickness and capable of stably exhibiting suitable development characteristics as shown in FIG. 1 can be manufactured with a shorter number of man-hours and at a lower cost.

Further, by rotating the surface processing tool around an axis perpendicular to the rotation axis of the workpiece and bringing it into contact with the surface of the workpiece, processing can be performed while smoothly discharging machining debris. Therefore, when a grindstone is used as a processing tool, clogging of the processing surface thereof is prevented, and a developer carrier having a smooth peripheral surface without scratches can be stably manufactured. It should be noted that the present invention should not be limited to the specific embodiments described above, and it goes without saying that various modifications can be made within the technical scope of the present invention. For example, when applying adhesive, it is also possible to use other immersion molding methods (dip molding), and in the process of applying electrode particles, the workpiece coated with adhesive is covered with electrode particles. It can also be carried out by rolling over a bed of particles. Furthermore, the surface processing for forming the dielectric layer 4 may also be carried out by the same method of grinding based on the outer surface as the surface processing of the electrode layer 2.

[Brief explanation of the drawing]

Fig. 1 is a graph showing suitable development characteristics, Fig. 2 is a schematic cross-sectional view showing a conventional developer carrier, and Fig. 3 shows the relationship between electrode thickness t2A and exposed area ratio AR. Graph diagram, FIG. 4 is an explanatory diagram showing the conventional manufacturing method, FIG. 5 is a perspective view showing the dielectric layer spraying process in one embodiment of the present invention, and FIGS. 6 and 7 are respectively Also dielectric coating Ill 4-
FIGS. 8 and 9 are schematic cross-sectional views showing the formation mode of the dielectric layer 4, and FIGS. Fig. 11 is a schematic cross-sectional view showing the electrode particle adhesion process and the amount of the electrode particles formed, Fig. 12 is a schematic cross-sectional view showing the thick adhesive coating process, and Fig. 13 is a schematic cross-sectional view showing the adhesive drying process. The schematic cross-sectional view shown in FIG. 14 is a schematic cross-sectional view showing the electrode layer forming process, and FIGS. 15(a) to 15(c) respectively show the electrode layer surface processing process by grinding. Each explanatory diagram,
FIG. 16(a) and FIG. 16(b) are a schematic side sectional view and a front sectional view showing the same completed developer carrier 11, respectively;
Figures 17(a) and 17<11) are explanatory diagrams showing the operation by the same grinding method, and Figure 18 is a schematic side sectional view showing a modified example of the completed developer carrier. It is. (Explanation of symbols) 1: Conductive support 2' two N-pole layers (before finishing) 2: Electrode layer (after finishing) 2a: Electrode particles 4: Dielectric layer 10: Grinding device patent applicant Rico Co., Ltd. - Chapter Figures 1 and 0 Figure 5 Figure 6 Figure 7 Figure 10 Figure 11 Figure 12

Claims (1)

[Scope of Claims] 1. A developer supported by a cylindrical conductive support, in which a number of conductive particles as electrodes are partially exposed on the surface and held in an electrically insulated state from each other. The method for manufacturing a body includes the steps of: forming a dielectric layer made of a dielectric material on the conductive support; depositing a dielectric adhesive on the dielectric layer; and applying the conductive particles to the surface of the dielectric layer. an electrode layer forming step in which an electrode layer is deposited on the conductive support; and a part of the end surface of a surface processing tool rotated about an axis perpendicular to the rotation axis of the conductive support is brought into contact with the surface of the electrode layer. A method for manufacturing a developer carrier, comprising the step of surface processing the surface of the electrode layer in contact with the surface of the electrode layer to expose a portion of each of the conductive particles on the surface. 2. Manufacturing a developer carrier according to item 1 above, wherein the surface processing tool is a grindstone, and the grindstone is rotated and moved in the direction of the rotation axis of the conductive support. Method.