JPH0656521B2 - Method for manufacturing developer carrier - Google Patents

Description

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 a one-component high-resistance magnetic toner. is there.

2. Description of the Related Art In an electrostatic recording device such as an electrophotographic copying machine, a facsimile or a printer, the developing characteristics required for a developing device differ depending on whether a document is a line image or a solid image. FIG. 1 is a graph showing the preferable developing characteristics, in which the horizontal axis represents the original image density and the vertical axis represents the copy image density. In the figure, the solid line A shows the development characteristics required for a solid image, and the broken line B shows the development characteristics required for a line image. According to this, the rising gradient of the line image (broken line B) is steeper than that of the solid image (solid line A). The reason for this is that if the original is a line image and the original image density is low, the sharpness of the image will be poor, so it is necessary to increase the copy image density to compensate for this, but if the original is a solid image, the original image density This is because if the corresponding copy image density is obtained, it is sufficiently clear.

By the way, in order to increase the copy image density of this line image, a so-called edge effect has been conventionally used. That is, as a result of the electric field strength at the image edge portion of the electrostatic latent image becoming stronger than the electric field strength at the image central area, a large amount of toner adheres to the image edge portion to cause an edge effect. Therefore, in the case of a line image having a small image area, most of the latent image forming area corresponds to the edge portion and is subjected to the edge effect, and the copy image density becomes a high value. Therefore, this edge effect can be obtained sufficiently when a two-component developer containing a toner and a carrier is used as a developer, but when a one-component developer containing no carrier is used. Has a drawback that it cannot obtain an effective edge effect.

Therefore, the applicant of the present application has proposed a developing device equipped with a developer carrying member having a unique structure that makes it possible to obtain the above-described suitable developing characteristics even when a one-component developer is used (Japanese Patent Application No. 55-55). -185726). The developer carrier according to this proposal is
As shown in FIG. 2, a large number of hemispherical fine electrode particles 2a made of a conductive material are scattered on the outer peripheral surface of the cylindrical conductive support 1 uniformly in the circumferential direction and the width direction. The electrode layer 2 is formed so that the individual electrode particles 2a are electrically insulated from each other and held in a floating state. If a magnetic developer is used, a magnet roller (not shown) is provided inside the support body 1.

As a suitable method for producing such a developer carrier, the adhesive 2b is applied on the conductive support 1 and the conductive particles 2a are sprinkled on the adhesive 2b, after which the outer diameter is machined by a lathe or the like. Has been proposed for smoothing the surface of the electrode layer 2 and shaving the electrode particles into a hemispherical shape to expose a part thereof on the surface. In this case, in order to obtain a 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, 4
It is required to secure at least 5%. Also, the electrode particles 2a
It is also necessary to avoid excising more than half of the volume of each particle in order to prevent desorption. In order to satisfy the above conditions, the electrode layer 2 may be formed so that the electrode thickness is 52 to 62 μm when the diameter of each electrode particle is about 74 to 104 μm. The electrode thickness refers to the thickness t _2A of the excised particles 2A in the direction of the electrode layer thickness t ₂ as shown in FIG. The reason is as follows.

FIG. 3 shows the thickness t _2A of the electrode particle 2a and its area ratio A _R.
It is a graph showing the relationship with. In Fig. 3, curves α, β and γ are the maximum electrode particles with a particle size of 104 μm, the electrode particles with an average particle size and the particle size of 74 μ, respectively.
Each relationship is shown for the smallest electrode particle of m. According to this, 45% required to obtain a suitable developing characteristic
More in order to ensure the area rate A _R, the smallest particle (curve gamma) at an area ratio A _R is the electrode thickness to be 45% or more t
The maximum value of ₂ A may be set to 62 μm. Maximum particles (curve α) to prevent detachment of particles by the anchor effect
It is necessary to secure a thickness t _{2A of} 52 μm or more, which is a half of the above. Therefore, the allowable range of the thickness t _2A of the electrode particles 2a is 52 to 62 μm.

However, when the outer diameter of the electrode layer is processed by a turning method that uses the axis (processing axis) that supports the workpiece such as a lathe as a reference,
It is difficult to suppress the fluctuation range of the thickness t ₂ of the electrode layer 2 below 10μm tolerance width of the electrode thickness t _2A, therefore disadvantageously also electrode thickness t _2A becomes difficult to fall within the allowable range (See Figure 2). That is, as shown in FIG. 4, since the conductive support 1 needs to be formed to be thin, it is difficult to process the spigot portions 1a at both ends thereof with high precision, and thus the support T of the lathe and Clearance P is likely to occur between the two. When the clearance P occurs,
It becomes difficult to match the central axis C ₀ of the support _{1 and} the central axis C ₁ (machining axis) of the support tool T. As a result, if the eccentricity of Δd between the center axis C ₀ and the machining axis C ₁ occurs, is thereby variation width V _R of the electrode layer thickness t ₂ that occurs, the layer thickness t
If ₂ of the maximum, the minimum value of each _{t MAX,} and _{t MIN,} the _{V R = t MAX -t MIN =} 2 · Δd. Therefore, in order to keep the electrode thickness t _2A within the allowable range of the width of 10 μm, the processing is performed under the precondition that the bottom surfaces of the electrode particles 2a are aligned at the same level H (see FIG. 2). The eccentricity amount Δd of the axis C ₁ is half that of 5 μ
It is required to keep it below m. It is extremely difficult to satisfy such severe processing conditions, which causes increase in man-hours and cost.

Aim The present invention has been made in view of the above points, and facilitates a developer carrier capable of exhibiting a desired edge effect and stably obtaining a high image quality even with a one-component developer. It is an object of the present invention to provide a manufacturing method that can be manufactured.

Configuration Hereinafter, the configuration of the present invention will be described in detail based on specific examples. As shown in FIGS. 16 (a) and 16 (b), the developer carrying member manufactured by the manufacturing method of the present example has a structure in which the dielectric layer 4 is adhered and formed on the conductive support 1 and then the electrode is formed. The developer carrying member 11 is formed by stacking layers 2.
The dielectric layer 4 is provided to secure a necessary dielectric region (dielectric thickness) on the conductive support 1 in order to prevent the edge effect.

First, as shown in FIG. 5, the conductive support 1 is formed into a cylindrical shape. In this case, when the magnetic developer is used as the developer and is applied to a developing device of a type that carries it by magnetic force, the conductive support 1 is made thin with non-magnetic material such as stainless steel.

Next, after degreasing the outer peripheral surface of the support 1, a dielectric coating film made of a dielectric material is uniformly applied over the entire outer peripheral surface. Specifically, for example, as shown in FIG. 5, a cylindrical sheathed heater 6 in which a heater 5 is mounted is provided rotatably horizontally, and the support 1 formed as described above is externally inserted and supported. While heating the body 1 to around 180 ° C. and rotating them substantially at a predetermined speed, the electrostatic coating gun 7 uniformly sprays the dielectric powder 4 ′ onto the outer peripheral surface of the support 1 by the electrostatic coating method. . In this case, dielectric powder 4 '
As the heat-effective resin powder, for example, epoxy resin powder or the like is suitable. Then, the coating gun 7 may be set parallel to the sheath heater 6 on a holding table (not shown) that can be reciprocally moved at a constant speed, and the spraying operation may be repeated until the target layer thickness of, for example, about 500 μm is reached. . After the spray coating is completed, the rotation of the support 1 is continued for an appropriate time while being heated by the sheath heater 6, and the dielectric coating film 4 is formed as shown in FIG.
Cure. Thus, the 'thickness t ₄ of _the' dielectric coating 4, a generally even in the circumferential direction as well as the width direction uniform. The method of heating the support 1 may be a method of heating from the outside with a far infrared heater or the like.

A large number of irregularities are usually formed on the surface of the deposited dielectric coating film 4 ', but in order to keep the thickness of the electrode particles within the above-mentioned allowable range, this surface must be smooth to some extent. Required. Therefore, to smooth the surface by applying an outer diameter machining by, for example, a lathe or the like deposited dielectric coating 4 'surface, the layer thickness t ₄ as shown in FIG. 7 to form a dielectric layer 4 of about 400μm . It is also possible to carry out the outer diameter processing by using another cylindrical grinder or the like.

After forming the dielectric layer 4 by the outer diameter processing, the surface of the dielectric layer 4 is cleaned, and then, as shown in FIG. 8, the surface of the dielectric layer 4 is dielectrically cured, for example, at room temperature by, for example, a pressure-feeding air spray 8. Spray and apply an adhesive such as acrylic urethane on the mold. As a result, the adhesive film 2b as shown in FIG. 9 is applied. The film thickness t _2B of the electrode film 2a dispersed in the next step (see FIG. 10) is, for example, 74 to 74. In the case of 104 μm copper particles, the dispersed particles can be surely adhered to the surface of the dielectric layer 3 to 15
About μm is preferable. 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 the work W) is suitable as in the case of forming the dielectric coating film. If the adhesive film 2b having a substantially uniform film thickness can be easily adhered and formed by supporting the film horizontally while rotating it at a speed and repeating the above-mentioned application of the adhesive along the film.

Once the adhesive is applied, a number of electrode particles are applied to the surface of the dielectric layer in a substantially uniform manner before it is cured. As an example of this attachment method, for example, as shown in FIG.
A large amount of copper particles having a diameter of μm are accommodated, the tray 9 is reciprocally moved at an appropriate speed along the work W supported and rotated horizontally, and the tray 9 is appropriately inclined, and the electrode particles 2 a are discharged from the spray port 9 a.
May be dropped little by little and sprinkled on the adhesive film 2b to be evenly distributed. As a result, as shown in FIG. 11, the electrode particles 2a are substantially evenly attached in contact with the surface of the dielectric layer 4. In this example, each electrode particle 2a to be attached is
Is previously coated with a dielectric substance such as styrene butyl acrylate, so that individual electrode particles 2a can be securely attached to the surroundings in an insulated state (float state) even if they are randomly scattered by natural fall. You can Further, since the thickness of the adhesive film 2b is as thin as 3 to 15 μm, buoyancy that can float the dispersed copper particles 2a having a particle size of 74 to 104 μm does not occur, and each particle 2a is naturally formed on the surface of the dielectric layer 4. It will be in a state of subsidence. Therefore, as shown in FIG. 11, the bottom surface of each electrode particle 2a can be easily and surely aligned with the surface of the dielectric layer 4 only by allowing the individual electrode particles 2a to fall naturally. In this example, copper particles are used as the electrode particles 2a, but the present invention is not limited to this, and other conductive particles such as brass, phosphor bronze, or styrene can also be used.

Next, after the adhesive 2b is almost completely dried and cured, the twelfth
As shown in the figure, the dielectric adhesive 2b 'is again thickly coated (overcoated) on the electrode particles 2a and the adhesive 2b in the same manner as the previous time. In this case, if an adhesive agent of the same material as the previous time is used, both are surely adhered to each other and can be more firmly fixed in a state where the electrode particles 2a are in contact with the surface of the dielectric layer 4, which is advantageous in terms of durability and the like. is there. Therefore, particles 2 adhere to each other
If a can be securely fixed, a combination of dielectric adhesives made of different materials is sufficiently possible. In this way, by applying the adhesive twice through the drying process, re-dissolution of the previously applied adhesive 2b is avoided, so that each electrode particle 2a does not float and the dielectric layer 4 does not float. It can be firmly fixed in a state of being submerged on the surface, and it is possible to easily achieve the above-mentioned precondition for keeping the electrode thickness within the predetermined allowable range such that the bottom surfaces of the respective particles 2a are aligned and positioned at the same level. .

After the thick coating of the adhesive is completed, it is dried and cured. In this case, as shown in FIG. 13, when the work W is externally mounted on the sheath heater 6 and horizontally supported and rotated as well as when the dielectric layer is formed, and the work W is dried while being heated, the thickly coated adhesive 2b 'is obtained. Adhesive 2 laminated on the dielectric layer 4 without sagging
b, a uniform layer thickness t _{2 'of} (a state before the part of each particle 2a is exposed to the surface) electrode particles 2a and thick coating adhesive 2b' electrode layer 2 combined '. In this way, for example, a layer thickness t ₂ is _'an electrode layer 2 of about 150 [mu] m' is formed.

Then, thereafter, as shown in FIG. 14, the electrode layer 2 '
The surface of is subjected to outer diameter processing to smooth the surface, and at the same time, a part of each electrode particle 2a is exposed on the surface to finish the electrode layer 2. By the way, in the method of the present invention, since the electrode particles 2a are fixed in contact with the surface of the dielectric layer 4, the layer thickness t ₂ of the electrode layer 2 after finishing is equal to the electrode thickness t _2A. . Therefore, Osamere the thickness _{t 2} of the electrode layer 2 is acceptable for the electrode thickness _{t 2A} 52 to within 62 .mu.m, and particle 2a exposed area rate _{A R} of the electrode particles 2a can be ensured more than 45% removal It is possible to obtain a desired electrode layer 2 that is difficult to separate.
Therefore, in the method of the present invention, the outer diameter processing step is performed by the surface processing method using the outer peripheral surface S (surface of the electrode layer 2 ') of the work W as a reference.

In this example, as shown in FIG. 15 (a), the support pair 1
A grindstone 10d as a surface processing tool is attached to the tip of a bar 10c which is rotatably supported on the shaft 0b via a shaft 10b.
The grinding device 10 provided with is used. The grindstone 10d is
As shown in FIG. 15 (b), a bowl C is formed, and in an inverted state thereof, an axis C perpendicular to the rotation axis C _W of the work W is shown.
_It is rotated about _B , and its side end face 10d ₁ is brought into contact with the peripheral surface of the work W rotated about the rotation axis C _W at a predetermined speed to perform grinding. Rotation axis C _{B of} grindstone 10d
The other end is connected to the drive motor 10f via the belt 10e. A weight 10g 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 10c.
By appropriately moving h, the pressure with which the grindstone 10d is brought into contact with the surface of the work W can be adjusted. Furthermore, in order to move the grindstone 10d along the axial direction of the work W,
The entire grinding device 10 is configured to be movable parallel to the axial direction of the work W. Then, as shown in FIG. 15 (c), the supporting pair 10a is attached to a tool rest (not shown) of the lathe, the work W is set on the main axis A of the lathe and rotated about the longitudinal axis, and the peripheral surface Then, the grindstone 10d is rotated around the rotation axis C _B and pressed, and is moved integrally with the tool rest in the direction of the longitudinal axis of the arrow to uniformly grind the entire peripheral surface.

By carrying out the grinding process in this way, the desired state as shown in FIGS. 16 (a) and 16 (b) can be stably obtained regardless of the position of the machining axis of the work W determined by the support condition of the spindle A. Of 5
The electrode layer 2 having a layer thickness t ₂ of ₂ to 62 μm is formed. That is, as shown in FIGS. 17 (a) and 17 (b), the support shaft C _A for supporting the work W by the main shaft of the lathe is the central axis C _{W of the} work _W (strictly speaking, in the case of this example, When the outer diameter of the layer 4 is decentered from the machining axis (during outer diameter machining) by Δd, the fluctuation range of the outer peripheral surface level H in contact with the grindstone 10d of the workpiece W rotated about the support axis C _A is twice as large as 2 · Δd. Becomes However, the rotatably supported bar 10c rotates in response to this fluctuation, and the grindstone 10d shown in FIG.
Even if the outer peripheral surface level H with respect to
Even if the outer peripheral surface level H shown in the figure is the highest, the grindstone 10d
The pressure contacting the outer peripheral surface of the work W is substantially constant. Therefore, in FIG. 14, the thickness t _2R to be ground from the initial electrode layer 2 ′ surface S (surface before grinding) of the work W is made uniform over the entire peripheral surface. . In this example, since 'the thickness t _2' electrode layer 2 is formed so as to be substantially uniform in 150 [mu] m, the grinding thickness over the entire circumference t
Grinding may be performed so that _2R becomes 88 to 98 μm. In this case, as shown in FIG. 18, even when the outer diameter machining axis C ₄ when forming the dielectric layer 4 is deviated from the central axis C ₀ of the support 1, even if the layer thickness of the dielectric layer 4 becomes uneven. The accuracy of the main grinding process is not affected, and the electrode layer 2 having a uniform layer thickness t ₂ can be stably formed with high accuracy. Further, since the area of the portion where the machined surface (end surface 10d ₁ ) of the grindstone 10d and the work W peripheral surface is in contact is small, the machined surface used for grinding is separated from the work peripheral surface in a short time, so that grinding scraps are machined quickly. Of the grindstone 10d is prevented from being clogged. Therefore, the occurrence of scratches on the peripheral surface of the work W due to clogging of the processed surface is eliminated.

As described above, the outer diameter of the electrode layer surface is applied to the outer peripheral surface as a reference, so that the layer thickness t ₂ , that is, the electrode thickness t _2A is from 52 to 52 as shown in FIGS. 16 (a) and 16 (b). 6
The electrode layer 2 reliably contained within the allowable range of 2 μm is uniformly formed over the entire peripheral surface. After that, if the surface is cleaned of dirt such as abrasives, the developer carrier 11 as a final product is completed.

Incidentally, in the above-mentioned embodiment, the step of applying the adhesive is divided into two officially, but this may be divided into one step or three or more steps as required. Further, the material of the dielectric layer 4 and the adhesive 2b
It is also possible that and are the same or the same type of dielectric material. Further, the material of the dielectric layer 4 is not limited to the thermosetting resin, but a thermoplastic resin such as polyimide or ABS can be used.

Effect As described above in detail, according to the present invention, by performing the surface processing for finishing the electrode layer that determines the electrode thickness on the basis of the electrode layer surface, the processing axis at the time of forming the electrode layer which is required to be dense. The setting of is unnecessary. Therefore, a developer carrying member having a desired electrode thickness and capable of stably exhibiting suitable developing characteristics as shown in FIG. 1 can be manufactured inexpensively in a shorter number of steps. Further, by rotating the surface processing tool about an axis perpendicular to the rotation axis of the object to be processed and bringing it into contact with the peripheral surface of the object to be processed, it is possible to smoothly discharge and process the processing waste. . Therefore, when a grindstone is used as the processing tool, the processing surface is prevented from being clogged, and a developer bearing member 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 above specific embodiments, and various modifications can be made within the technical scope of the present invention. For example, when applying an adhesive, another dip molding method (dip molding method)
Etc., and the step of adhering the electrode particles can also be carried out by rolling a work piece coated with an adhesive on a particle bed on which the electrode particles are spread. Further, the surface processing for forming the dielectric layer 4 may be carried out by the same grinding method based on the outer surface as the surface processing of the electrode layer 2.

[Brief description of drawings]

Figure 1 is a graph view showing a preferred development characteristics, Figure 2 is a schematic cross-sectional view illustrating a conventional developer carrying member, a third diagram the relationship between the electrode thickness t _2A and exposed area ratio A _R FIG. 4 is an explanatory view showing a conventional manufacturing method, FIG. 5 is a perspective view showing a dielectric layer spraying step in one embodiment of the present invention, FIG. 6, FIG. Are schematic cross-sectional views showing the manner of forming the dielectric coating film 4'and the dielectric layer 4, respectively, and FIGS. 8 and 9 are schematic diagrams showing the adhesive 2b applying step and the formed product, respectively. Sectional views, FIGS. 10 and 11 are schematic sectional views respectively showing the electrode particle adhering step and its formed product, and FIG. 12 is a schematic sectional view showing the adhesive thick coating step, respectively. FIG. 13 is a schematic sectional view showing the adhesive drying step, FIG. 14 is a schematic sectional view showing the electrode layer forming step, and FIG. ) To 15 (c) are explanatory views each showing an electrode layer surface processing step by grinding, and Figs. 16 (a) and 16 (b) show the completed developer carrier 11 respectively. The schematic side sectional view and the front sectional view, FIG. 17 (a) and FIG. 17 (b), respectively, are explanatory views showing the operation by the grinding method, and FIG. 18 is the same completed developer carrier. It is a typical side sectional view showing a modification of a body. (Explanation of symbols) 1: Conductive support 2 ': Electrode layer (before finishing) 2: Electrode layer (after finishing) 2a: Electrode particles 4: Dielectric layer 10: Grinding device

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yoshio Miyazaki 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Co., Ltd. (72) Inventor San-ichi Sakurai 1-3-6 Nakamagome, Ota-ku, Tokyo No. Ricoh Co., Ltd. (56) Reference JP-A-60-125852 (JP, A) JP-A-60-125854 (JP, A)

Claims (2)

[Claims] 1. A method for producing a developer carrier, comprising a cylindrical conductive support, a plurality of conductive particles as electrodes, each part of which is exposed on the surface and kept electrically insulated from each other. In the method, a step of forming a dielectric layer made of a dielectric material on the conductive support, depositing a dielectric adhesive on the dielectric layer, and attaching the inductive particles to the surface of the dielectric layer. An electrode layer forming step of depositing and forming an electrode layer by contacting the electrode layer surface with a part of the end face of a surface processing tool rotated about an axis perpendicular to the rotation axis of the conductive support. A surface treatment step of subjecting the surface of the electrode layer as a reference to exposing a part of the conductive particles to the surface, and a method of manufacturing a developer carrier. 2. The developer carrying member according to claim 1, wherein the surface processing tool is a magnet, and the grinding stone is rotated and moved along the rotational axis direction of the conductive support. Body manufacturing method.