CN201373979Y - Powder supply roller and developing device - Google Patents

Abstract

The utility model provides a powder supply roller and a developing device having the powder supply roller, which are applied to electronic photographic image forming devices such as copiers and printers. The developing device includes a container for storing developer, a developing roller for supplying developer to a photosensitive body, and a powder supply roller for supplying developer to the developing roller, and the powder supply roller is composed of a core tube and a plurality of fibers implanted on the surface of the core tube. The surfaces of the core tube and the fibers are conductive or semi-conductive, and the surface of the top end of the fibers is electrically insulating. The utility model can achieve the purpose of extending the service life and stabilizing the charge amount of the developer at a low price, and can inhibit the generation of developers with opposite charges.

Description

Toner supply roller and developer

technical field

The utility model relates to a powder supply roller and a developing device used in image forming devices of electrophotography such as copiers and printers.

Background technique

In electrophotographic image forming apparatuses such as copiers and printers, a developing device 1 as shown in FIG. 5 is generally used. The developing roller 3 in the developing device 1 applies fine granular toner to the electrostatic latent image formed on the surface of the photosensitive drum 2 to visualize it. The peripheral surface of the toner supply roller 4 is in contact with the peripheral surface of the developing roller 3 to supply toner. On the peripheral surface of the developing roller 3, the top end of the doctor blade 5 is also in contact with it, and is pushed by the push spring 6 to form a prescribed carbon powder layer thickness. A toner container 7 for storing toner is provided around the toner supply roller 4 . Bias power sources 8 , 9 provide a negative voltage for electrostatically moving toner to developing roller 3 and toner supply roller 4 .

Since the carbon powder is physically transported to the surface of the developing roller 3, the surface of the powder supply roller 4 is preferably in a shape that can physically hold the carbon powder. Therefore, the powder supply roller 4 is usually formed by covering the periphery of the metal tube core 10 with a conductive sponge layer 11 . The developing roller 3 is provided with an electrically insulating rubber layer 13 around a metal die 12 , and a protective layer 14 is provided on the outer peripheral surface of the rubber layer 13 . On the surface of the photosensitive drum 2, an electrically insulating photo-semiconductor layer is formed as an image carrier.

Fig. 6 shows an outline of a powder supply roller manufacturing method. Insert the pipe core 10 that metals such as stainless steel are made to be cut into the conductive sponge piece 15 of square prism shape, cut and make the outer peripheral surface of conductive sponge piece 15 be cylindrical surface, form conductive sponge layer 11 (referring to Fig. 5 and Figure 7). The conductive sponge layer 11 is fixed to the die 10 by a conductive adhesive.

FIG. 7 shows the state of the engaging portion 16 which is the contact portion of the developing roller 3 and the toner supplying roller 4. As shown in FIG. A plurality of recesses 18 capable of holding carbon powder 17 are formed on the surface of the conductive sponge layer 11 . The toner 17 is supplied to the surface of the developing roller 3 through the recesses 18 on the surface of the sponge layer, and is further physically adhered to the developing roller 3 by forming an electric field between the developing roller 3 and the supply roller 4 . At this time, on the surface of the developing roller 3, the concave portion 18 on the surface of the conductive sponge layer 11 is shrunk back, and the carbon powder 17 on the surface of the developing roller is in sliding contact and the contact pressure is relatively large. Inside, the toner 17 is at risk of being fixed.

FIG. 8 shows a method of forming an electric field. To develop the electrostatic latent image on the photoreceptor, a voltage generating a necessary potential difference is applied to the developing roller 3 . Usually, when the surface potential of the photoreceptor is set to be about -650V, the developing bias applied to the developing roller 3 is preferably about -350V. In order to electrostatically move the carbon powder from the toner supply roller 4 to the development roller 3, a voltage of necessary polarity and electric field is applied to the toner supply roller 4, typically -400V to -700V, such as -650V.

The powder supply roller 4 used as above is required to have the following characteristics: 1. the electric charge of the carbon powder is not leaked. ②In order for the toner not to be charged with the opposite polarity, it is necessary to pay attention to the triboelectrification sequence and select the material. ③The powder supply roller is not charged, and moderate conductivity is necessary. ④When the toner supply roller touches the developing roller, in the meshing area, the toner supply roller forcibly squeezes the toner to the developing roller 3, so that the toner is not charged with unnecessary triboelectricity, and the conductive sponge is managed with high precision The hardness of the layer, foam rate, meshing width, etc. are necessary. ⑤In the way that the toner supply roller slides into contact with the surface of the developing roller, scrapes off the toner on the contact surface, and regenerates it, the state of the toner supply roller surface must be kept stable no matter it is electrically or mechanically. (6) Electrical characteristics that do not affect the bias voltage applied to the developing roller 3 are required. Regarding the electrical impedance, it is preferable to be equal to or higher than the impedance of the developing roller 3 . ⑦It will not bring the necessary mechanical pressure to the toner. ⑧ Use materials that will not damage the developing roller.

As shown in Figure 5, the existing supply roller 4 that covers the conductive sponge layer 11 on the surface conveys toner through the concave-convex shape of the surface. The voltage of the roller 3 is required for the function of generating an electric field between the developing roller 3 and the toner supply roller 4 to electrostatically attract the toner to the developing roller 3 efficiently. However, the following problems will arise on the conductive sponge layer 11 on the surface of the powder supply roller 4: ① It is not easy to manage the foaming rate of the conductive sponge layer. Also easy to change. To ensure this specified property, it is necessary to produce sponges with less variation, but this is difficult. ②Because the conductive sponge itself is easily deformed, it is not easy to form a perfect circle and meet the specified value during production. For example, the shape accuracy of the sponge is about ±0.2mm. For example, the diameter Φ of the developing roller is 20mm, and the diameter Φ of the powder supply roller is 16mm. Under this precision, when the sinking amount of the sponge is 0.5mm±0.2mm, the meshing width is 3mm to 5mm, and the change will affect the developing roller. 3 has a large influence on the contact resistance and the friction electrification of the toner. In addition, since such processing is necessary, the manufacturing cost increases. ③ The sponge roller as the powder supply roller 4 is formed by installing a conductive sponge layer around the metal tube core 10, and the tube core 10 and the conductive sponge layer 11 are fixed with a conductive adhesive. It is difficult to uniformly adhere between the die 10 and the conductive sponge layer 11, and there is a significant difference in the electrical characteristics of the surface between the adhered part and the non-adhered part. ④ Fixing the carbon powder 17 to the concave portion 18 on the surface of the conductive sponge layer 11 increases the electrical resistance, significantly hinders the conveyance of the carbon powder 17, and increases the driving torque. Therefore, comparatively shorten the service life of powder supply roller 4. ⑤Also, for the developing roller 3, the pressing force on the surface of the toner supply roller increases, and unnecessary pressure is applied to the toner, resulting in a significant change in the shape or surface state of the toner, making it impossible to maintain a stable image. ⑥The pressing force on the surface of the toner supply roller 4 increases, and unnecessary frictional electrification and filming on the developing roller tend to occur.

These phenomena appear as the following problems on the image formed by development: ①The density is not uniform due to the unstable supply of toner. ②Concentration changes and fog density increases due to changes in toner characteristics.

In addition, when the conductive sponge layer 11 of the toner supply roller 4 brings a significant change to the charge amount of the carbon powder, and produces a toner with a polarity opposite to the specified polarity, the non-image on the photoreceptor 2 Unnecessary toner adheres to the inside. Since the toner adhering to the photoreceptor 2 has a polarity opposite to the prescribed polarity, it is hardly transferred to the recording paper due to electrostatic repulsion in the electrostatic transfer method. However, after the toner remaining on the photoreceptor 2 is recovered from the photoreceptor 2 by cleaning equipment, it is returned to the regeneration mode (recycle) for reuse in the developing device or the residual toner is cleaned at the same time during the development stage, that is, the so-called In the non-cleaning member method, the concentration (ratio) of the oppositely charged toner in the developing device increases with the increase of printing, which hinders the image quality.

In addition, these carbon powders are easy to electrostatically adhere to the contact charging methods such as charging rollers or charging brushes. The charging equipment is contaminated by these carbon powders and cannot be charged normally, which is likely to cause uneven charging. In particular, in the no-cleaning member system, it is difficult to collect the toner under static electricity by the developing roller 3, and the toner remains attached to the photoreceptor 2, deteriorating the image quality.

Also, as the powder supply roller 4, when a metal roller is used, since the resistance value of the powder supply roller 4 is remarkably low, it is used without contact. Thus, the above-mentioned problems caused by contact do not occur. However, in the case of a metal roller, the surface is generally smooth, and the transferability of the toner powder is poor, and concentration unevenness is likely to occur. Also, due to the non-contact, in order to keep the electric field strength formed between the developing roller 3 and the supply roller 4 constant, it is necessary to manage the gap between the developing roller 3 and the supply roller 4 with high precision. In addition, due to non-contact, the toner that has passed through the development stage is peeled off from the developing roller 3, and the effect of supplying toner called reset (reset) is completely unpredictable, so ghost images and the like are generated and the image is damaged. quality.

Utility model content

The first object of the present utility model is to provide a toner supply roller capable of solving the above problems, prolonging the service life and stabilizing the charged amount of the developer at a low price, and suppressing the generation of the oppositely charged developer. .

The second object of the present utility model is to provide a developing device having the above powder supply roller.

In order to achieve the above first objective, the utility model provides a powder supply roller, the powder supply roller implants a plurality of fibers on the surface of its core tube. The toner supply roller supplies the developer to the developing roller, and the developing roller supplies the developer to the electrostatic latent image on the photoreceptor to visualize the electrostatic latent image.

According to the present invention, the extended fibers are implanted on the surface of the powder supply roller in a desired posture, that is, at an angle ranging from 0° to 90° relative to the radial direction, and the developer is kept in the gaps between the fibers, In the contact or adjacent area between the developing roller and the powder supply roller fiber, the developer is directly squeezed to the surface of the developing roller without sliding contact, which will not bring unnecessary triboelectric charge to the developer, or change the belt that the developer has. electricity. Also, no mechanical stress is exerted on the developer. Moreover, since the fiber vibrates along with the rotation of the developing roller, the developer is fixed to the surface of the toner supply roller, so there is no need to worry about shortening the service life, and the purpose of having a longer service life is achieved. In the case of using the toner supply roller to remove the developer on the developing roller for renewal, compared with the conventional wiping off with the conductive sponge layer in a surface-to-surface contact state, the developer is removed by bouncing off the toughness of the fiber, so it is not necessary Unnecessary pressure is applied to the developer. Also, since almost no frictional resistance is generated between the developing roller and the toner supply roller, the driving torque can be reduced.

In addition, the core tube of the powder supply roller of the present invention has a conductive or semiconductive surface, and the fibers also have a conductive or semiconductive surface, so that a stable electric field can be formed between the powder supply roller and the developing roller, and prevent Charging can maintain the stability of the electrical characteristics of the toner supply roller and stabilize the transfer amount of developer from the toner supply roller to the developing roller. The surface of the core tube and the fiber has the following conditions: (a) the surface of the core tube and the fiber is conductive; (b) the surface of the core tube is conductive and the surface of the fiber is semiconductive; (c) the core tube The surface of the fiber is semiconductive and the surface of the fiber is conductive; (d) both the surface of the core tube and the fiber are semiconductive. The so-called conductivity means that the resistance between one end of all the fibers implanted by a powder supply roller and the other end of all the fibers is in the range of 10 ⁶ Ω to less than 10 ⁹ Ω, and the so-called semi-conductivity means that the resistance between 10 ⁹ Ω to 10 ¹² Ω.

In addition, the top surface of the fiber of the powder supply roller of the present utility model has electrical insulation, even if the top end of the fiber contacts the developing roller, the developing roller and the powder supply roller will not be in an energized state, and can stably maintain their respective surface potential.

In the present invention, the fiber contains an electrically insulating or semiconductive substrate and a conductive polymer layer covering the surface of the substrate, and can be manufactured more easily and at low cost to make the whole conductive. The conductive polymer is an electron conductive material. By using a polypyrrole-based conductive polymer as an electron-conductive material, conductivity can be easily imparted to various types of substrates.

In order to achieve the second purpose above, the utility model provides a developing device used in an electrophotographic image forming device for supplying a developer to a photoreceptor forming an electrostatic latent image to develop the electrostatic latent image. change. The developing device includes: a container for storing developer; a developing roller for supplying the developer to the photoreceptor; a powder supply roller for supplying the developer in the container to the developing roller, and the powder supply roller is implanted with multiple fibers. According to the utility model, the developer conveyed between the fibers on the surface of the core tube of the powder supply roller is smoothly transferred to the developing roller, thereby performing stable development.

Description of drawings

Fig. 1 is a cross-sectional view of a schematic configuration of Embodiment 1 of the present invention.

FIG. 2 is an enlarged view of a contact portion of the developing roller 23 and the supply roller 24 of FIG. 1 .

Fig. 3 (a) is the schematic structural view of the fiber 32 in Fig. 2; Fig. 3 (b) is the structural schematic view of the fiber 32 ' with overall conductivity.

FIG. 4 is a schematic diagram of forming the hair-planted part 31 of FIG. 1 by electrostatic hair-planting method.

FIG. 5 is a simplified cross-sectional view of a conventional toner supply roller 4 and a developing device 1 .

FIG. 6 is a schematic diagram of a manufacturing method of the powder supply roller 4 of FIG. 5 .

FIG. 7 is a schematic cross-sectional view of a contact portion between the developing roller 3 and the toner supply roller 4 of FIG. 5 .

FIG. 8 is a model diagram of an electrical connection state between the developing roller 3 and the toner supply roller 4 of FIG. 5 .

Detailed ways

Fig. 1 shows a general configuration of Embodiment 1 of the present invention. The developing device 21 includes a developer container 27, a developing roller 23, a toner supply roller 24, and a doctor blade 25 as a developer control member. The developing roller 23 and the toner supply roller 24 are electrically conductive, and bias voltages of −350 V and −650 V are applied from bias power sources 28 and 29 , respectively. The configuration of the developing roller 23 is basically the same as that of the prior art developing roller 3 shown in FIG. 5 . The powder supply roller 24 forms a hair-planting portion 31 around the core tube 30 .

The core pipe 30 is a straight cylinder, which can be: (a) a cylinder made of metal; (b) a cylinder made of electrically insulating synthetic resin, with a structure in which a conductive layer or a semiconductive layer is formed on its surface ; (c) The electrically insulating paper tube body is preferably formed with a conductive layer or a semiconductive layer on its surface. This conductive layer or semiconductive layer may be formed by plating with metal or the like, or may be formed with a conductive or semiconductive adhesive in the electrostatic hair-planting method described later.

The edge of the scraper 25 controls the amount of developer attached to the developing roller 23 by approaching and separating from the surface of the developing roller 23 , and may also be in contact with the top end like the scraper 5 shown in FIG. 5 .

FIG. 2 shows the state of the meshing portion where the toner supply roller 24 and the developing roller 23 are in contact with FIG. 1 . Fibers 32 extending in the radial direction of the developing roller 23 are implanted at a constant density in the hair-implanted portion 31 . The developer 37 is held in the gaps between the fibers 32 . On the surface of the fibers 32 is formed a conductive polymer layer 33 covering a central electrically insulating substrate 34 . At the top end of the fiber 32, the aforementioned conductive polymer layer 33 is removed, and the fiber 32 directly contacts the surface of the developing roller 23 through its electrical insulating substrate 34. Since it will not be in an electrified state, the developing roller 23 and the powder supply The bias voltage of the roller 24 is maintained stably. Since the fiber 32 has a certain degree of toughness, if the developer remains on the developing roller 23, it will be bounced off and removed without applying pressure.

FIG. 3( a ) shows the fiber 32 of this example, and FIG. 3( b ) shows a fiber 32 ′ having electrical conductivity as a whole. In the overall conductive fiber 32' shown in FIG. 3(b), conductive layers such as carbon rod layers 35 exist between layers of an electrically insulating material, forming the base material itself. It is difficult to manufacture such conductive parts as the carbon rod layer 35 and the like as the base material itself, and the manufacturing cost increases. For the conductive polymer layer 33 of the present embodiment shown in FIG. 3( a ), it is preferable to use a polypyrrole-based conductive polymer such as a trade name "STpoly" manufactured by Achilles Co., Ltd. In polypyrrole-based conductive polymers, it is considered that generated diocations and the like in the main chain of the polymer move between the main chains to transport charges and exhibit conductivity. The thickness of the layer surface of such polypyrrole is 0.1 μm to 0.5 μm, so it can impart electrical conductivity without losing the characteristics of the material. The electrical conductivity can be freely set within the range of the aforementioned electrical impedance of 10 ² Ω to 10 ⁷ Ω. Since the mechanism for imparting electrical conductivity is electron conductivity through dications, in the case of ion conductivity, humidity does not change electrical conductivity, and electrical conductivity can be maintained stably.

As the electrically insulating base material 34, fibers made of electrically insulating synthetic resins such as acrylic resin, polyester, and nylon can be used. In order to improve the adhesiveness of the conductive polymer layer 33 and the base material 34, it may pre-process as needed. The base material 34 is about 3 deniers, and the length is 1.0 to 3.0 mm, preferably 1.2 to 1.5 mm. Thus, the surface of the core tube 30 can be electrostatically implanted, and if it is too long, the density of the implanted wool will be reduced. Also at the tip portion of the fiber 32, the conductive polymer layer 33 is removed and an electrically insulating portion 36 is formed.

FIG. 4 schematically shows the process of forming the hair-planted portion 31 on the surface of the powder supply roller 24 in FIG. 1 by electrostatic hair-planting method. A conductive or semiconductive adhesive layer 39 is coated around the core tube 30 , and a high voltage is applied between a pair of parallel plate electrodes 41 , 42 separated by a certain distance up and down in FIG. 4 through a DC power supply 38 . The horizontal axis 43 of the core tube 30 is parallel to the horizontal electrodes 41 , 42 . Within this electric field electric field lines are generated parallel to an imaginary vertical plane 45 containing the axis 43 . On the electrode 41 on the high-potential side of the power source 38, a plurality of fibers 32 of the same length set in advance are carried. Between the core pipe 30 and the electrode 41, a flat plate-shaped control member 48 made of an electrically insulating material such as synthetic resin is provided. A slit 44 is formed in the control part 48 , and the slit 44 extends parallel to the axis 43 of the core tube 30 . In the state of FIG. 4 including the axis 46 of the slit 44 on the imaginary plane 45 including the axis 43 , the elongated fiber 32 flying along the electric field line is attached to the radial direction of the core tube 30 through the adhesive layer 39 .

In other embodiments of the present invention, the slit 44 of the control component 43 can also be set to be displaced from the imaginary plane 45 in FIG. 4 to its left or right. Thereby, the fiber 32 adheres to the surface of the core tube 30 in a posture inclined radially with respect to the core tube 30 .

During electrostatic hair planting, the core tube 30 rotates along the direction of the arrow 47, therefore, the fiber 32 passing through the slit 44 is attached to the fiber 32 in the radial direction of the core tube 30, or at a desired angle relative to the radial direction. , so that the hair can be planted on the whole peripheral surface of the core pipe 30. The state in which the axis 46 of the slit 44 is within the aforementioned imaginary plane 45 and parallel to the axis 43 of the core tube 30 is shown in FIG. 4 . The polarity of the DC power supply 38 is opposite to that of FIG. 4 , and it is also possible to set the fiber 32 to the electrode on the low potential side.

At the tip of the fiber 32, in order to form an electrical insulating portion 36 as shown in FIG. The conductive polymer layer 33 can be formed.

In other embodiments of the present invention, a predetermined gap can be provided between the photoreceptor and the developing roller, and the developer can jump over the gap through the surface potential difference of the photoreceptor, which is the so-called jumping developing method. As mentioned above, the utility model can also be used well in the development mode of supplying non-magnetic single-component carbon powder to the developing roller. In addition, the developer can also be a two-component material composed of carrier and carbon powder. developer.

Claims (10)

1. A powder supply roller, comprising a core tube, characterized in that: a plurality of fibers are implanted on the surface of the core tube. 2. The powder supply roller according to claim 1, wherein the core tube has a conductive or semiconductive surface. 3. The powder supply roller according to claim 2, characterized in that the fibers have a conductive or semiconductive surface. 4. The powder supply roller according to claim 3, wherein the tip end of the fiber has an electrically insulating surface. 5. The powder supply roller according to claim 3, characterized in that the fibers comprise an electrically insulating or semiconductive substrate and a conductive polymer layer covering the surface of the substrate. 6. A developing device, comprising: Containers for storing developer; A developing roller that supplies developer to the photoreceptor; a toner supply roller for supplying developer to said developing roller, the toner supply roller having a core tube; It is characterized by: A plurality of fibers are implanted on the surface of the core tube of the powder supply roller. 7. The developing device according to claim 6, wherein the core tube has a conductive or semiconductive surface. 8. The developing device according to claim 7, wherein the fibers have a conductive or semiconductive surface. 9. The developing device according to claim 8, wherein the tip of the fiber has an electrically insulating surface. 10. The developing device according to claim 8, wherein the fibers comprise an electrically insulating or semiconductive substrate and a conductive polymer layer covering the surface of the substrate.

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