JP2005316376A - Developing device, process cartridge and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a developing device capable of maintaining image quality by preventing the leakage of developer inside a sealing member at the end of a developer thin layer on a developer carrier while keeping the developer thin layer uniform. <P>SOLUTION: In the developing device, the outside diameter of the center part 14c of the doctor roller 14 is made larger than the outside diameter of the end 14d of the doctor roller 14, so that the doctor roller 14 has both-side symmetrical shape with center at the center part 14c, and an outside diameter curve CL showing the outside diameter of the doctor roller 14 is a curve based on a general expression for obtaining the deflection of a uniform-load both-end supporting beam. An end area γ where the outside diameter of the doctor roller 14 becomes larger than the value of the outside diameter curve CL is provided toward the end 14d of the doctor roller 14 from the inside in the shaft direction of an end sealing member 20 at the end 14d of the doctor roller 14. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an image forming apparatus such as a copying machine, a facsimile machine, or a printer, and more particularly to an image forming apparatus using a one-component developer.

Conventionally, in this type of image forming apparatus, after the surface of the image carrier is uniformly charged, the surface of the image carrier is selectively irradiated with light based on the image information, so that the latent image is formed on the image carrier. An image is formed. This latent image is developed by a one-component developing device using toner as a one-component developer, and then transferred to a transfer material by a transfer device.
The one-component developing device includes a container that contains a one-component developer, and a developer carrier that is rotatably supported by an opening of the container and carries the developer. A developer supply member that supplies the developer to the developer carrier and a developer regulating member that regulates the developer carried and conveyed by the developer carrier. The developer supplied onto the developer carrying member by the developer supplying member is regulated to a predetermined layer thickness at the contact portion between the developer carrying member and the developer regulating member, and the developer thin film on the developer carrying member. The layer is formed and frictionally charged by being rubbed against the developer regulating member.
In an image forming apparatus having such a developing device, if a transfer material of A3 size or larger can be used, both the image carrier and the developer carrier and the developer regulating member become longer in the axial direction. Deflection occurs in the developer regulating member biased. This deflection becomes larger at the axially central portion. When deflection occurs in the developer regulating member, the contact pressure of the developer regulating member with respect to the developer carrying member becomes non-uniform, and in particular, there is a gap between the developer regulating member and the developer carrying member at the central portion in the axial direction of the developer regulating member. Will occur. When the gap is generated, the developer regulating member cannot regulate the layer thickness of the developer on the developer carrying member, and the developer layer becomes thick at the center of the developer carrying member. In the central portion of the developer carrier, a gap is generated, so that it is difficult to be frictionally charged by the developer regulating member.Moreover, since the developer layer is thick and the amount of the developer is large, the developer in the central portion of the developer carrier is Charge amount is very low. When developing with a developer having a very low charge amount, there is a problem that fogging occurs or developer scattering occurs.

  In view of this, the present inventors disclosed in Patent Document 1 that the outer diameter of the central portion in the axial direction is larger than the outer diameters of both ends in order to bring the developer regulating member into uniform contact with the developer carrying member. Then, a developing device having a developer regulating member that is symmetrical on both sides around the center has been proposed. As a result, the outer diameter of the developer regulating member becomes larger at the central portion where the deflection becomes larger, and the developer regulating member having a uniform outer diameter is used for the contact pressure of the developer regulating member with respect to the developer carrying member. Since it becomes more uniform, the developer thin layer can be formed more uniformly.

JP 2002-99144 A

  However, the developing apparatus disclosed in Patent Document 1 has the following problems. The developer scraped off from the developer carrier by the developer regulating member tends to flow from the center toward both ends, and the developer flow defines the developer thin layer width of the developer carrier. It stops when it is regulated by the end seal part. Therefore, in the vicinity of the inside of the seal member, a considerably large powder pressure is generated by the developer as compared with the central portion. In the vicinity of the inner side of the seal member at the end of the developer thin layer, the contact pressure of the developer regulating member cannot suppress the flow of the developer that tries to move in the direction of movement of the developer carrying member. Then, the developer that is not a thin layer slips through the contact portion between the developer carrier and the developer regulating member. The slipped developer scatters from the opening of the container as the developer carrying member rotates, and developer leakage occurs. When this development leakage occurs, the developer leaked from the container stains the inside of the image forming apparatus, and if the developer adheres to the image carrier or the developer carrier having a different color, the image quality is deteriorated.

  The present invention has been made in view of the above problems, and the object of the present invention is to keep the developer thin layer uniform on the developer carrying member while keeping the developer thin layer inside the seal member at the end of the developer thin layer. Provided is a developing device capable of maintaining the image quality by preventing the developer from leaking out of the container, the developer slipping out of the contact portion between the developer carrier and the developer regulating member, and the developer leaking. It is to be.

In order to achieve the above-mentioned object, the invention of claim 1 accommodates a one-component developer, has a developing container having an opening, and is exposed from the opening so as to face an image carrier outside the developing container. A developer carrier that is disposed and carries the developer; a developer supply member that supplies the developer to the developer carrier; and a developer carrier that is in contact with the surface of the developer carrier. A developer regulating member that regulates the amount of the developer carried and conveyed, and an axial end of the developer carrying body so as to prevent developer leakage from the end of the developer carrying body to the outside of the developing container. In a developing device having an end seal member that rubs against the surface, the developer restricting member is symmetrical on both sides about the axial center, and the developer restricting member is in a central region sandwiched between both axial ends. In accordance with the deflection of the member, the closer to the center in the axial direction, the larger the outer diameter of the developer regulating member. A shape in which the outer diameter of the developer regulating member is larger than the outer diameter of the shape in accordance with the deflection in the end region on the axial end side of the central region, and the central region and the end region The boundary is located on the center side in the axial direction with respect to the end seal member.
According to a second aspect of the present invention, in the developing device of the first aspect, the boundary between the central region and the end region is larger than both ends of the image guarantee region where the maximum width guarantees the quality of the formed image. It exists in the axial direction end side.
According to a third aspect of the present invention, in the developing device according to the first or second aspect, the outer diameter in the central region changes based on a general formula for determining the deflection of the both end support beams of the equally distributed load. The outer diameter at is a value larger than the outer diameter determined based on the general formula.
According to a fourth aspect of the present invention, in the developing device of the first, second, or third aspect, the outer diameter of the boundary between the central region and the end region, and the outer diameter of the axial center of the developer regulating member Wherein the outer diameter of the developer regulating member in the end region is within ± dφ / 10 of the outer diameter of the boundary between the central region and the end region. It is.
Further, the invention of claim 5 is the developing device of claim 1, 2, 3 or 4, wherein the developer regulation per 1.0 [mm] in the axial direction of the central region of the developer regulating member. The difference between the maximum value and the minimum value of the distance from the rotation center of the member to the surface is 12.5 μm or less.
The invention according to claim 6 is the developing device according to claim 1, 2, 3, 4 or 5, wherein the development per 1.0 [mm] in the axial direction of the central region of the developer regulating member. The difference between the maximum value and the minimum value of the distance from the rotation center to the surface of the agent regulating member is 10 μm or less.
According to a seventh aspect of the present invention, there is provided an image comprising: an image carrier that carries a latent image; an exposure device that forms a latent image on the image carrier; and a developing means that develops the latent image on the image carrier. In the forming apparatus, the developing device of claim 1, 2, 3, 4, 5 or 6 is used as the developing means.
According to an eighth aspect of the present invention, there is provided a process cartridge that integrally supports at least one of an image carrier, a charging device, an exposure device, and a cleaning device and a developing device, and is detachable from the main body of the image forming device. The apparatus is a developing apparatus according to claim 1, 2, 3, 4, 5 or 6.

  In the developing device according to any one of claims 1 to 8, the outer diameter in the end region of the developer restricting member is made larger than the outer diameter of the shape matching the deflection of the developer restricting member, so that the development inside the seal member is performed. The contact pressure between the agent carrier and the developer regulating member can be made larger than before. As a result, even if a developer powder pressure that is considerably larger than that in the central portion is generated in the vicinity of the seal member, the developer slips through the contact portion due to the contact pressure of the developer regulating member against the developer carrier. Can be suppressed.

  According to the first to sixth aspects of the present invention, it is possible to prevent the developer from slipping through the developer regulating member in the vicinity of the inside of the seal member, thereby preventing the developer from leaking out of the container. And has an excellent effect that the image quality can be maintained.

[Embodiment]
Hereinafter, an embodiment in which the present invention is applied to a copying machine such as a printer as an image forming apparatus will be described.
FIG. 1 is a front view illustrating a schematic configuration diagram of a printer according to the present embodiment. This printer includes a photosensitive belt 1 as an image carrier that is wound around a plurality of support rollers. The photosensitive belt 1 is driven to rotate in the clockwise direction indicated by an arrow in the figure, and therearound is a charging device 3, an optical writing unit 4, four sets of developing devices 5Bk, 5C, 5M, 5Y, and an intermediate transfer member. The intermediate transfer belt 6 and the photoconductor cleaning device 7 are disposed. An organic photosensitive layer is formed on the surface of the photoreceptor belt 1.

  When an image forming operation (printing operation) is performed by this printer, the photosensitive belt 1 is uniformly charged by applying a high voltage to the charging device 3. In an image signal processing unit (not shown), color image information, for example, a color 4 image signal sent from an external computer is converted into an optical writing signal and sent to the optical writing unit 4 as an exposure apparatus. In the optical writing unit 4, a laser as a light source (not shown) is controlled based on the optical writing signal. Then, optical writing corresponding to the image signals of Black (Bk), Cyan (C), Magenta (M), and Yellow (Y) is performed through the polygon mirror, the f / θ lens, and the reflection mirror, and the photosensitive belt 1 An electrostatic latent image is formed thereon. The electrostatic latent image on the photosensitive belt 1 is provided for each color by the developing devices 5BK, 5C, 5M, and 5Y each having toner of each color as a developer charged with a charge having a polarity opposite to that of the latent image. Developed. As a result, a toner image is formed for each color on the photosensitive belt 1.

  At the contact portion between the photosensitive belt 1 and the intermediate transfer belt 6, the toner image on the photosensitive belt 1 is transferred onto the intermediate transfer belt 6 by applying a charge having a polarity opposite to that of the toner to the intermediate transfer belt 6. The By repeating this toner image formation and transfer operation four times, a four-color color toner image is formed on the intermediate transfer belt 6. The color toner image on the intermediate transfer belt 6 is transferred by a paper transfer roller 43 as a secondary transfer member to a transfer paper as a recording material sent from a paper feed cassette 40 or a manual feed tray 41 by a conveying roller pair 42. Is done. The transfer paper onto which the color toner image has been transferred is conveyed to a fixing unit comprising a fixing roller pair 44, and the toner image is melted and fixed.

Next, the developing device according to this embodiment will be described. The developing devices 5BK, 5C, 5M, and 5Y according to the present embodiment have the same configuration and operation except for the color of the toner to be stored. Therefore, the developing device 5 will be described by omitting the symbols BK, C, M, and Y.
FIG. 2 is a cross-sectional view showing a schematic configuration of the developing device 5. An independently rotatable cam 50 is in contact with the side end portion (left side in the figure) of the developing device 5. The cam 50 is configured to perform a contact / separation operation so as to move away from the photosensitive belt 1 during non-development and to move the developing roller 11 to a developing position where the developing roller 11 contacts the photosensitive belt 1 prior to development. . For example, when an electrostatic latent image of Bk is formed on the photosensitive belt 1, the cam positioned at the rear of the developing device 5Bk is driven to rotate, the developing device 5Bk is pushed out to the photosensitive belt 1 side, and the developing roller 11Bk. Moves to the developing position where it contacts the photosensitive belt 1. The same applies to the developing devices 5C, 5M, and 5Y of other colors.

  The developing device 5 is a one-component developing type developing device using a non-magnetic one-component toner (hereinafter referred to as toner) as a developer. Each developing device 5 includes a developing container 10 having an opening toward the photosensitive belt 1, a developing roller 11 as a developer carrying member, and a toner supply as a developer supplying member that supplies toner onto the developing roller 11. A roller 12 is provided. In addition, transport paddles 17a, 17b, and 17c are provided that send toner stored in toner storage portions 18a, 18b, and 18c in the developing container 10 to the toner supply roller 12 side. In addition, it has a doctor roller 14 as a developer layer regulating member that abuts on the developing roller 11 and regulates the layer thickness of the toner carried on the developing roller to form a toner layer having a predetermined layer thickness. Yes.

  The developing roller 11 has a resin coating portion on the surface of the metal core, which is coated with a resin coating wider than the image forming region width. The developing roller 11 coated with resin has a merit that high durability can be obtained because the developing roller 11 carries and conveys the toner by electrostatic holding force generated by friction between the resin and the toner. As the resin material to be coated, a material that is non-staining to the latent image carrier such as the photoreceptor belt 1 is selected. Specifically, urea resin, melamine resin, alkyd resin, modified alkyd resin such as phenol modification / silicone modification, acrylic resin, silicone resin, fluorine resin, phenol resin, polyamide resin, epoxy resin, polyester resin, maleic acid resin, etc. Is exemplified. In particular, urea resin, melamine resin, acrylic resin, and the like are often used from the viewpoint of film formability and adhesion.

  Part of the developing roller 11 having such a configuration is exposed from the opening of the developing container 10. Then, during development, the toner rotates on the developing roller 11 at a predetermined linear speed and is conveyed to a developing position which is a contact portion with the photosensitive belt 1. The electrostatic latent image formed on the surface is developed.

  The toner supply roller 12 is in contact with the developing roller 11 with a predetermined pressure, and the surface portion is made of foamed polyurethane. A toner regulating blade 13 abuts on the toner supply roller 12 so that the amount of toner supplied to the developing roller 11 is regulated. Each transport paddle 17 is installed so as to be rotatable counterclockwise as indicated by an arrow, and the toner is sent to the supply roller 12 side by this rotation. As a material of each transport paddle, for example, a material having soft elasticity such as polypropylene can be used, and the toner is reliably transported by rotating in close contact with the inner wall of the developing container 10 using the elasticity.

The doctor roller 14 has a cored bar and an elastic layer such as urethane rubber or hydrin rubber coated with resin. The doctor roller 14 contacts the surface of the developing roller 11 to regulate the toner on the developing roller 11 to a predetermined layer thickness, and frictionally charges the toner by slidingly contacting the toner. The doctor roller 14 is in contact with a doctor roller cleaning blade 16 so that the surface of the doctor roller 14 that has passed through the contact portion with the developing roller 11 is cleaned.
FIG. 3 is a side view of the developing roller 11 and the doctor roller 14. As shown in FIG. 3, the pressing member 19 supports the shaft portions 14 b at both ends of the doctor roller 14 via the bearing portion 14 e, and the pressing member 19 presses the doctor roller 14 against the developing roller 11. By pressing the doctor roller 14 against the developing roller 11 by the pressing member 19, it is possible to prevent a change in the contact state between the developing roller 11 and the doctor roller 14 due to environmental fluctuations such as humidity.

  In order to prevent the toner from leaking from the gap between the developing roller 11 and the developing container 10, an inlet serving as an inlet seal member that extends so that the tip of the developing container 10 contacts the surface of the developing roller 11. A seal 15 is provided. Further, in order to prevent the toner from leaking from the gap between the axial end of the developing roller 11 and the developing container 10, an end seal member that slides on the surface of the developing roller 11 is provided on the side plate of the developing container 10. It has been. 4 is a sectional view showing the arrangement of the end seal 20 of the developing roller 11, FIG. 5 is a perspective view showing the arrangement of the end seal 20 of the developing roller 11, and FIG. It is a perspective view of a container 10 side plate.

Next, the shape of the doctor roller 14 in the axial direction will be described. If the outer diameter of the doctor roller 14 is the same and has a uniform shape at any position in the axial direction, the doctor roller 14 is deflected by a load applied to the doctor roller 14. When the deflection occurs, the contact pressure between the doctor roller 14 and the developing roller 11 becomes uneven depending on the position in the axial direction. If the contact pressure becomes non-uniform, the layer pressure of the toner layer on the developing roller 11 also becomes non-uniform, and the toner charge amount is partially reduced at the portion where the toner layer is too thick.
In the present embodiment, in order to make the contact pressure between the doctor roller 14 and the developing roller 11 more uniform, as shown in FIG. 7, the outer diameter of the central portion in the axial direction of the doctor roller 14 is made larger than the outer diameters of both ends. The size is increased and the two sides are targeted at the center.

At this time, if the deflection of the doctor roller 14 is calculated by a model of a general support beam having both ends of an equally distributed load,
w = q * L ⁴ / (24EI) * (x / L) * (1-2 * (x / L) ² + (x / L) ³ ).
Here, w is the amount of deflection at the position x, q is a value obtained by dividing the total load by the length of the doctor roller 14, L is the length of the doctor roller 14, E is the Young's modulus of the shaft 14b, and I is the secondary moment of section. in a π ^* d 4/64, d is the diameter of the shaft 14b.
From the above equation, w is a quartic function for x. Therefore, if the outer diameter φ of the doctor roller 14 is changed in a curve based on the above-mentioned quartic function in the axial direction, the doctor roller 14 is theoretically compared with a curve using other functions. Can be pressed more uniformly against the developing roller 11. As a result, the toner layer on the developing roller 11 can be made uniform, the toner charge amount can be kept constant, and a partial drop thereof can be prevented, and the image quality can be improved. An outer diameter curve indicating the shape of the outer diameter of the doctor roller 14 along the curve based on the quartic function at this time is indicated by CL in the drawing. Incidentally, in FIG. 7, the outer diameter difference between the doctor roller center 14c and the doctor roller end portion 14d is increased for easy understanding, but the actual outer diameter difference is 50 to several hundred μm.

  The toner scraped off from the developing roller 11 by the doctor roller 14 tends to flow from the doctor roller center 14c toward the doctor roller end portion 14d. The toner flow is stopped by being regulated by the end seal member 20 that defines the toner thin layer width of the developing roller 11. An explanatory view of the vicinity of the doctor roller end 14d at this time is shown in FIG. In the region α in the vicinity of the end seal member 20, a considerably large powder pressure is generated by the flowing toner as compared with other regions on the doctor roller 14. As shown in the drawing, the contact pressure of the doctor roller 14 against the developing roller 11 moves in the surface movement direction of the developer roller 11 at the end of the toner thin layer TL, in other words, at the inner end of the end seal member 20. The toner flow to be attempted cannot be suppressed, and toner leakage TO occurs. As shown in FIG. 9, the toner leakage TO is caused by the toner passing through the contact portion between the developing roller 11 and the doctor roller 14 from the area A where the toner is blocked by the doctor roller 14, and from the downstream side in the rotation direction of the developing roller 11. It leaks out of the developing container 10. As described above, when the toner leakage TO occurs, the inside of the image forming apparatus becomes dirty, and if the photosensitive belt 1 or the inside of the developing device of another color is stained, the image quality is deteriorated.

  Therefore, in the present embodiment, as shown in FIG. 10, an end region γ having an outer diameter larger than the outer diameter curve CL, which is a curve based on a general formula for obtaining deflection, is formed from the inside of the end seal member 20. It is provided over the doctor roller end 14d. Here, the doctor roller 14 can be divided into an end region γ in the axial direction and a region β that is a central region that determines the outer diameter of the doctor roller 14 according to the outer diameter curve CL. The boundary between the region β and the end region γ is set as the inflection point CP. As shown in the figure, the position of the inflection point CP is provided inside the end portion of the toner thin layer TL formation region while making the outer diameter larger than the outer diameter curve CL indicated by the dotted line in the end region γ. Thereby, the doctor roller contact pressure in the vicinity of the end seal member 20 is made larger than the contact pressure in the central region β, and toner leakage at the end of the toner thin layer TL is prevented. That is, by providing the end region γ from the region C to the region B in the figure, the contact pressure of the doctor roller 14 against the developing roller 11 in the region α in FIG. 8 is made larger than the contact pressure in the central region β. And the occurrence of toner leakage TO in the region α can be prevented. By the way, when the inflection point CP enters the end seal region, that is, when the end region γ is only in the region B, the contact pressure in the vicinity of the inside of the end seal member 20 cannot be increased. The occurrence of toner leakage TO cannot be prevented.

  Further, the inflection point CP is provided outside the both end portions (boundary with the region C in the figure) of the image guarantee region D, which is the maximum width that guarantees the quality of the formed image. In the image guarantee area D, it is necessary to make the contact pressure as uniform as possible so as not to cause a density deviation in the axial direction. Therefore, it is desirable to configure the inflection point CP outside the image guarantee area D. Incidentally, the outside of the inflection point CP is the end region γ, and the contact pressure is larger than the inside of the inflection point CP. Therefore, the toner thin layer TL is thinner in the region α than the image guarantee region D. . As a result, the toner thin layer TL in the image guarantee area D can be made uniform and toner leakage in the vicinity of the end seal portion can be prevented.

Here, the implementation conditions for the doctor roller 14 of the present embodiment are shown below.
Doctor roller diameter: φ14 (rubber layer: 1 mm)
Difference between roller maximum outer diameter (center) and inflection point outer diameter: 240 μm
Distance from end seal to inflection point: 2mm (* 7mm from doctor roller end)
End seal and doctor roller wrap amount: 5mm
Outer diameter difference between doctor roller end and inflection point: 0
Doctor roller axial length: 320mm
Image guarantee area width: 300mm

As shown in FIG. 11, the outer diameter of the doctor roller 14 at the inflection point CP is φB, the outer diameter at the doctor roller end portion 14d is φC, and the outside of the doctor roller end portion 14d and the inflection point CP is outside. The range that the diameter difference (φC−φB) can take was examined by experiment. At this time, the outer diameter φC of the doctor roller end 14d is the maximum value of the outer diameter in the end region γ. As a result of repeated experiments by the inventors, the difference in outer diameter from the inflection point to the end is set to ± 20 μm, thereby preventing the occurrence of fogging in the image guarantee area and the toner leakage near the end seal. I found out that I could do it. Here, toner leakage occurs at −20 μm or less, and fogging occurs when the contact pressure at the central portion decreases at +20 μm or more.
By the way, it seems that the allowable range of the outer diameter difference (φC−φB) has a relationship with the flexibility of the doctor roller. In this embodiment, dφ = 240 μm, φC−φB = ± 20 μm, where dφ is the difference in outer diameter between the center of the doctor roller that takes the maximum outer diameter according to the deflection and the inflection point.
Therefore, in general, it seems that it is appropriate that φC−φB = ± dφ / 10. In addition, by setting φC−φB = ± dφ / 20 or less, it is possible to more reliably prevent the occurrence of toner leakage and fogging.

  The shape of the doctor roller 14 is such that the outer diameter of the doctor roller 14 becomes an outer diameter curve CL of a quartic function that takes the apex at the center 14c of the doctor roller so that it contacts the developing roller 11 in accordance with the deflection of the doctor roller 14. Designed. However, when actually created, the outer diameter of the position measured with an arbitrary range width is created so as to match the outer diameter curve CL, and there is a small undulation when the minute range of the surface of the doctor roller 14 is viewed locally. The outer diameter curve CL does not completely coincide.

A schematic diagram of the undulation in this minute range is shown in FIG. FIG. 13 shows the state of surface undulation in the range of 1 mm in the axial direction of the doctor roller 14. d1 is the distance from the rotation center of the doctor roller 14 to the surface of the undulation convex part, and d2 is the distance from the rotation center of the doctor roller 14 to the surface of the undulation concave part.
Here, if there is an excessive difference in the distance from the rotation center of the doctor roller 14 to the surface between the adjacent convex portion and the concave portion, the contact of the doctor roller 14 with the developing roller 11 becomes poor, and the toner may slip through the minute gap TP. there were. When the toner slips through the minute gap TP, problems such as image unevenness and toner scattering occur.

  Therefore, the occurrence of local contact failure is prevented by defining the difference in the distance from the center of rotation between the concave and convex portions on the surface per 1 mm in the axial direction. When toner having an average particle diameter of 7 μm is used, in the central region β, the difference between adjacent convex portions and concave portions, that is, d1-d2 is set to 12.5 μm or less to prevent the toner from slipping through the minute gap TP. did it. Even when d1-d2 is larger than the average particle diameter of the toner used, the toner can be prevented from slipping through because the toner is not perfectly spherical and the surface of the doctor roller 14 is an elastic layer. This is because the toner cannot pass through due to crushing. If the difference between adjacent irregularities is 12.5 μm or less, the toner can be prevented from slipping through. Therefore, the maximum value and the minimum value of the distance from the rotation center of the doctor roller 14 to the surface per unit length of 1 mm in the axial direction can be prevented. If the difference from the value is 12.5 μm or less, the toner can be prevented from slipping through the entire central region β.

  On the other hand, since the powder pressure of toner is higher in the end region γ than in the central region β, the pressure at which the toner tries to slip through increases. Therefore, by setting d1-d2 of the end region γ to 10 μm or less with respect to the toner having an average particle diameter of 7 μm, the toner can be prevented from slipping through the minute gap TP. As described above, by defining the value of d1-d2 smaller in the end region γ than in the central region β, it is possible to prevent the toner from slipping through. If the difference between adjacent irregularities is 10 μm or less, toner can be prevented from slipping through. Therefore, the maximum value and minimum value of the distance from the rotation center of the doctor roller 14 to the surface per unit length of 1 mm in the axial direction If the difference is 10 μm or less, the toner can be prevented from slipping through the entire end region γ.

  In the above description, the minute undulation generated in the member production has been described. However, the difference between the maximum value and the minimum value of the distance from the rotation center of the doctor roller 14 per unit length to the surface is limited to this. is not. For example, the present invention can also be applied when minute scratches or dents are generated during the assembly of the device or during the transportation of members. If the difference between the maximum value and the minimum value of the distance from the rotation center of the doctor roller 14 to the surface per 1 mm around the scratch or dent is 12.5 μm or less in the central region β and 10 μm or less in the end region γ, Can prevent the toner from slipping through. As described above, the difference between the maximum value and the minimum value of the distance from the rotation center of the doctor roller 14 per unit length to the surface can be used as an index for product management for distinguishing good products from defective products.

As described above, according to the present embodiment, the outer diameter of the doctor roller center 14c is larger than the outer diameter of the doctor roller end portion 14d, and the doctor roller center 14c has a bilaterally symmetric shape. At this time, the shape of the outer diameter is a quaternary function outer diameter curve CL having a vertex at the center 14c of the doctor roller so as to contact the developing roller 11 in accordance with the deflection of the doctor roller 14. Thus, by matching the outer diameter of the doctor roller 14 with the deflection, the contact pressure of the doctor roller 14 against the developing roller 11 becomes uniform in the axial direction, and a uniform toner thin layer TL can be formed. . Further, the doctor roller 14 is provided with an end region γ having an outer diameter larger than the outer diameter curve CL from the inner side of the end seal member 20 toward the end portion of the doctor roller 14. As a result, the contact pressure of the doctor roller 14 against the developing roller 11 in the region α in the vicinity of the inside of the end seal member 20 can be made larger than the contact pressure in the central region β, and at the end of the toner thin layer TL. Toner leakage in a certain region α can be prevented.
Further, by providing the end region γ where the contact pressure is larger than the other regions outside the image guarantee region D, the contact pressure can be kept uniform in the image guarantee region D, and the uniform toner thinness can be maintained. A layer TL can be formed.
Further, the outer diameter curve CL is a quaternary function curve for obtaining the deflection of the both-end supporting beam of the general distribution load. As a result, it is possible to match the deflection of the doctor roller 14 more faithfully than using another function curve, so that the contact pressure is more uniform, and the toner thin layer TL having a more uniform thickness can be formed.
Further, the outer diameter φC of the doctor roller end portion 14d is φC−φB = dφ / 10 with respect to the outer diameter difference dφ between the inflection point CP and the doctor roller center 14d and the outer diameter φB of the inflection point CP. To be. As a result, it is possible to prevent the occurrence of fog due to the outer diameter of the end region γ being too large and the occurrence of developer leakage due to the outer diameter of the end region γ being too small.
Further, the difference between the maximum value and the minimum value of the distance from the rotation center of the doctor roller 14 to the surface per unit length 1.0 [mm] in the axial direction of the central region β is set to 12.5 μm or less. As a result, it is possible to prevent local toner slippage due to minute undulations on the surface of the doctor roller 14 in the central region β, and it is possible to prevent background contamination and toner scattering.
Further, the difference between the maximum value and the minimum value of the distance from the rotation center of the doctor roller 14 to the surface per unit length 1.0 [mm] in the axial direction of the end region γ is set to 10 μm or less. As a result, it is possible to prevent local toner slippage due to minute undulations on the surface of the doctor roller 14 in the end region γ, and it is possible to prevent background contamination and toner scattering.

  In this embodiment, the quaternary function for obtaining the deflection of the both-end supporting beam of the normal distribution load is applied as the outer diameter curve CL. However, the outer diameter of the shape according to the deflection is not limited to this. . For example, a quadratic function, a circular arc, or the like described in Patent Document 1, such that the contact pressure between the doctor roller and the developing roller is uniform in the axial direction, and is in contact with the end more than other regions The present invention can be applied by providing an end region where the pressure increases.

[Modification 1]
By the way, in this embodiment, although the some developing roller 11 contact | abuts with respect to the one photoreceptor belt 1, it does not restrict to this. FIG. 12 is a schematic diagram of an image forming unit in which one photosensitive roller is provided for each developing roller as a first modification. Here, the photosensitive roller 101, the charging member 31, the cleaning member 71, and the developing device 52 are integrally supported to form a process cartridge 51. As described above, a plurality of components such as the photosensitive member, the charging device, the developing device, and the cleaning device are integrally combined as a process cartridge, and the process cartridge is configured as a main body of an image forming apparatus such as a copying machine or a printer. And detachable.
As a result, since the developing device having the doctor roller applied in the present embodiment is used, it is possible to maintain a good image quality without toner contamination while realizing a uniform toner thin layer in the image guarantee area. . Furthermore, it is possible to provide a process cartridge that facilitates maintenance and replacement of image forming means.

1 is a schematic configuration diagram of a printer according to an embodiment. Sectional drawing which shows schematic structure of a developing device. The side view which shows the state which pressed the doctor roller to the developing roller. Sectional drawing which shows arrangement | positioning of the edge part seal | sticker of a developing roller. The perspective view which shows arrangement | positioning of the edge part seal | sticker of a developing roller. FIG. 3 is a perspective view of a developing container side plate showing an arrangement of end seals. The side view of a developer control member. The side view which shows the mode of a developer leak. Sectional drawing which shows the mode of a developer leak. The side view of the developer control member which has an edge part area | region. Explanatory drawing of the edge part of the developer control member which has an edge part area | region. FIG. 10 is a cross-sectional view illustrating a schematic configuration of a process cartridge according to a first modification. The schematic diagram of the wave | undulation in the micro range of the doctor roller surface.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Photoconductor belt 3 Charging device 4 Optical writing unit 5 Developing device 6 Intermediate transfer belt 7 Photoconductor cleaning device 10 Developing container 11 Developing roller 12 Toner supply roller 13 Toner regulating blade 14 Doctor roller 14a Doctor roller elastic layer 14b Doctor roller shaft 14c Doctor roller center 14d Doctor roller end 14e Doctor roller bearing 15 Inlet seal 16 Doctor roller cleaning blades 17a, 17b, 17c Conveyor paddles 18a, 18b, 18c Toner container 19 Press member 20 End seal member 40 Paper feed cassette 41 Manual feed tray 42 Conveying roller pair 43 Paper transfer roller 44 Fixing roller 50 Cam 51 Process cartridge

Claims (8)

A developer container containing a one-component developer and having an opening;
A developer carrying member that is exposed from the opening and is opposed to an image carrier outside the developing container, and carries the developer;
A developer supply member for supplying the developer to the developer carrying member;
A developer regulating member that regulates the amount of the developer carried and conveyed by the developer carrying body in contact with the surface of the developer carrying body;
In the developing device comprising an end seal member that slidably rubs against the surface of the end portion in the axial direction of the developer carrier so as to prevent the developer leakage from the end portion of the developer carrier to the outside of the developer container.
The developer regulating member is symmetrical on both sides around the axial center,
In the central region sandwiched between both axial ends, the outer diameter of the developer regulating member increases in proportion to the deflection of the developer regulating member, closer to the axial center,
In the end region on the axial end side of the central region, the outer diameter of the developer regulating member is larger than the outer diameter of the shape in accordance with the deflection,
2. A developing device according to claim 1, wherein a boundary between the central region and the end region is closer to a central side in the axial direction than the end seal member. The developing device according to claim 1.
2. A developing device according to claim 1, wherein a boundary between the central region and the end region is located on an axial end side from both ends of the image guarantee region which is a maximum width for guaranteeing a quality of an image to be formed. The developing device according to claim 1 or 2,
The outer diameter in the central region changes based on the general formula for obtaining the deflection of the both ends support beam of the equally distributed load,
The developing device according to claim 1, wherein the outer diameter in the end region is larger than the outer diameter determined based on the general formula. The developing device according to claim 1, 2 or 3,
When the difference between the outer diameter of the boundary between the central region and the end region and the outer diameter of the axial center of the developer regulating member is dφ,
The developing device, wherein an outer diameter of the developer regulating member in the end region is within ± dφ / 10 of an outer diameter of a boundary between the central region and the end region. The developing device according to claim 1, 2, 3 or 4,
The difference between the maximum value and the minimum value of the distance from the rotation center of the developer regulating member to the surface per 1.0 [mm] in the axial direction of the central region of the developer regulating member is 12.5 μm or less. A developing device characterized by the above. The developing device according to claim 1, 2, 3, 4 or 5.
The difference between the maximum value and the minimum value of the distance from the rotation center of the developer regulating member to the surface per 1.0 [mm] in the axial direction of the central region of the developer regulating member is 10 μm or less. A developing device. In an image forming apparatus comprising: an image carrier that carries a latent image; an exposure device that forms a latent image on the image carrier; and a developing unit that develops the latent image on the image carrier.
An image forming apparatus using the developing device of claim 1, 2, 3, 4, 5, or 6 as the developing means. In a process cartridge that integrally supports at least one of an image carrier, a charging device, an exposure device, or a cleaning device and a developing device and is detachable from the image forming apparatus main body,
7. A process cartridge according to claim 1, wherein the developing device is the developing device according to claim 1, 2, 3, 4, 5 or 6.

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