Developing device, regulating member, process cartridge, and image forming apparatus

Abstract

The present invention discloses a developing device, a regulating member, a process cartridge, and an image forming apparatus. The developing device includes a frame, a cylindrical developer carrying member, and a regulating member including a contact portion. When the position of the contact portion indicating a maximum pressure distribution of the contact portion on the developer carrying member relative to the rotational direction of the developer carrying member is a reference position, the contact portion includes a first region upstream of the reference position relative to the rotational direction and a second region downstream of the reference position. The contact portion has a smaller surface roughness in the first region than in the second region. The surface roughness in the second region is 20% or less of the average particle size of toner particles contained in the developer.

Description

Technical Field

[0001] The present invention relates to an image forming apparatus, and a developing device, an adjusting member, and a process cartridge used in the image forming apparatus. In particular, the present invention relates to an electrophotographic image forming apparatus employing an electrophotographic type, and a developing device, an adjusting member, and a process cartridge used in the electrophotographic image forming apparatus. Background Art

[0002] Conventionally, in a developing device used in an image forming apparatus, a developing blade is used as a member for controlling the amount of developer carried on the surface of a developing roller.

[0003] Generally, one end of the developer blade contacts the surface of the developer roller and forms an appropriate contact pressure during the rotation of the developer roller so that a coating layer having a substantially uniform developer amount (layer thickness) can be formed on the developer roller. Furthermore, when the developer passes through the contact nip between the developer roller and the developer blade, the developer contained in the coating layer is rubbed, so that an electric charge (triboelectric charge) is imparted to the developer by frictional charging.

[0004] Furthermore, from the perspective of reducing energy consumption, developers used in image formation are being demanded to have a "low melting point." In order to prevent even developers (toner particles) with a low melting point from being easily crushed by the "contact pressure" between the developing roller and the developing blade, Japanese Laid-Open Patent Application (JP-A) Hei 11-249422 proposes a configuration that defines the shape of the developing blade. According to the configuration of JP-A Hei 11-249422, the "contact pressure" is reduced, thereby reducing the fusion of toner particles into component parts caused by the crushing of toner particles.

[0005] However, in order to further improve image quality, improvements in the "particle size reduction" of the developer have been demanded. With smaller particle sizes, the configuration of JP-A Hei 11-249422, as in conventional configurations, may easily reduce the uniformity of the developer amount (coating) on ​​the developing roller due to slight variations in the shape and contact pressure of the developing blade. Furthermore, there is a possibility that the charge amount of the developer, charged by friction, may become insufficient. In this case, streaky image defects with respect to the vertical direction (the direction in which the recording paper is fed) and image defects causing uneven image density (non-uniformity) may easily occur in the printed image. Summary of the Invention

[0006] In view of the above problems, a main object of the present invention is to provide a configuration capable of easily enhancing the uniformity of the amount of developer (developer coat) while suppressing a decrease in the charging performance of developer particles contained in the developer coat.

[0007] According to one aspect of the present invention, a developing device is provided, comprising: a frame; a cylindrical developer carrying member, which is rotatably supported by the frame and configured to carry a developer containing colorant particles; and a regulating member, which is fixed to the frame at one end thereof and includes a contact portion, which contacts the developer carrying member at the other end of the regulating member and forms a contact nip between itself and the developer carrying member, wherein, when the position of the contact portion indicating the maximum value of the pressure distribution of the contact portion on the developer carrying member relative to the rotational direction of the developer carrying member is a reference position, the contact portion includes a first region upstream of the reference position and a second region downstream of the reference position relative to the rotational direction, and wherein the contact portion has a smaller surface roughness in the first region than in the second region, and the surface roughness in the second region is 20% or less of the average particle size of the colorant particles contained in the developer.

[0008] Further features of the present invention will become apparent from the following description of exemplary embodiments with reference to the attached drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 is a schematic cross-sectional view illustrating a contact state between a developing blade and a developing roller used in the image forming apparatus according to an embodiment of the present invention.

[0010] Figure 2 is a schematic cross-sectional view of an image forming apparatus according to an embodiment of the present invention.

[0011] Figure 3 is a schematic cross-sectional view of a developing blade used in the image forming apparatus according to an embodiment of the present invention.

[0012] Figure 4 is a schematic cross-sectional view of a development blade in a modified embodiment of the embodiment of the present invention. DETAILED DESCRIPTION

[0013] Hereinafter, an electrophotographic image forming apparatus according to the present invention will be described with reference to the accompanying drawings.

[0014] Incidentally, the embodiments described below merely illustratively describe the present invention, and regarding the sizes, materials, shapes, relative positional relationships, etc. of the constituent elements described below, the scope of the present invention is not limited thereto unless otherwise specified.

[0015] Here, the electrophotographic image forming apparatus refers to an apparatus for forming an image on a recording medium (material) by using an electrophotographic type. In addition, examples of the electrophotographic image forming apparatus include an electrophotographic copier, an electrophotographic printer (e.g., a laser beam printer, an LED printer, etc.), a facsimile machine, a word processor, etc.

[0016] Furthermore, a developing device used in an image forming apparatus includes at least a developing unit. A regulating member is a component that is one of the components constituting the developing unit included in the developing device. The developing device can be incorporated into a cartridge (unit) that is attachable to and detachable from the main assembly of the electrophotographic image forming apparatus.

[0017] Furthermore, a process cartridge that forms part of an image forming apparatus is prepared by integrally assembling a charging unit, a developing unit, or a cleaning unit with an electrophotographic photosensitive drum into a cartridge, and is capable of being installed in and removed from the main assembly of the electrophotographic image forming apparatus. Furthermore, this cartridge is prepared by integrally assembling at least one of the charging unit, the developing unit, and the cleaning unit with the electrophotographic photosensitive drum into a cartridge, and is capable of being installed in and removed from the main assembly of the electrophotographic image forming apparatus. Furthermore, there are process cartridges that are prepared by integrally assembling a developing unit and an electrophotographic photosensitive drum into a cartridge, and are capable of being detachably attached to the main assembly of the electrophotographic image forming apparatus. Incidentally, the process cartridge can also be used while being fixed to the image forming apparatus.

[0018] [Example]

[0019] In the following, based on Figures 1 to 4 The embodiments of the present invention are described in detail.

[0020] <Overall Structure of Image Forming Apparatus>

[0021] First, refer to Figure 2 , the overall structure of the image forming apparatus according to this embodiment will be described. Figure 2 is a schematic cross-sectional view of the image forming apparatus according to this embodiment.

[0022] like Figure 2 As shown in FIG, the image forming apparatus 100 according to this embodiment includes a process cartridge 1 configured to be attachable to and detachable from the image forming apparatus. That is, the process cartridge 1 can be inserted into and removed from the apparatus main assembly 100 a.

[0023] The process cartridge 1 is formed of a developing unit (developing device) 2 as a developing member and a photosensitive drum unit 3. The photosensitive drum unit 3 is composed of a photosensitive member 11 as an image bearing member, a charging roller 21 as a charging member for charging the photosensitive member 11, and a cleaning blade 61 as a cleaning member for the photosensitive member 11.

[0024] Incidentally, around the photosensitive member 11, there are provided a charging roller 21 and a developing roller 41 which is installed in the developing unit 2 and carries a toner as a developer (T) so as to develop the electrostatic latent image formed on the surface of the photosensitive member 11 with the developer. Furthermore, around the photosensitive member 11, there are provided a transfer roller 51 for transferring the toner from the photosensitive member 11 to the recording material R and a cleaning blade 61 for removing transfer residual toner remaining on the photosensitive member 11 without being transferred to the recording material R.

[0025] Furthermore, in the developing unit (developing device) 2, around the developing roller 41, there is provided a toner supply roller 42 for supporting the toner to the developing roller 41 and for scraping the toner off the developing roller 41. Furthermore, in the developing unit 2, there is provided a developing blade 43 as a (toner amount) regulating member for regulating the amount of toner supplied to the developing roller 41 to a desired toner amount (thickness of the coating).

[0026] Furthermore, the toner image formed of the toner and transferred onto the recording material R is fixed to the recording material R under application of a predetermined pressure and a predetermined heat when the recording material R passes through the fixing device 71 .

[0027] Incidentally, a transfer roller 51 and a laser exposure unit 31 for forming an electrostatic latent image corresponding to image data on the charged photosensitive member 11 are also mounted in the apparatus main assembly 100 a of the image forming apparatus 100 .

[0028] Furthermore, in the image forming apparatus 100 , a voltage source (not shown) for applying a predetermined voltage to the charging roller 21 , the developing roller 41 , the developing blade 43 , the toner supplying roller 42 , and the transfer roller 51 is installed.

[0029] <Image Forming Operation>

[0030] Next, refer to Figure 2 , the image forming operation in the image forming apparatus of this embodiment will be described in detail.

[0031] In this embodiment, when the image forming operation starts, the photosensitive member 11 is rotationally driven by a motor (not shown) in the photosensitive member direction Rd. Incidentally, the surface speed of the rotationally driven photosensitive member 11 is 180 mm / sec.

[0032] The photosensitive member 11 is a so-called organic photosensitive member in which a charge generation layer is formed on a conductive core metal such as aluminum and a charge transport layer is formed on the charge generation layer. In this embodiment, the layer thickness of the charge transport layer is 23 μm.

[0033] The charging roller 21 in contact with the photosensitive member 11 is a roller having a surface coated with a predetermined resistance layer on a cylindrical conductive support member, and the cylindrical opposite end portions of the conductive support member are pressed by springs so that the charging roller 21 rotates as the photosensitive member 11 rotates. Incidentally, a negative voltage of -1100 V is applied from a charging voltage source (not shown) to the charging roller 21 at a predetermined timing so as to charge the surface of the photosensitive member, so that the surface of the photosensitive member 11 is uniformly negatively charged, thereby becoming -500 V as a "dark portion potential."

[0034] Incidentally, the laser exposure unit 31, which exposes the charged photosensitive member 11 to light, exposes the surface of the photosensitive member 11 with a laser beam in the main scanning direction (the direction of the photosensitive member's rotational axis). Furthermore, exposure is also performed with matching timing with the sub-scanning direction (the direction in which the photosensitive member's surface rotates), forming an "electrostatic latent image." The image-forming portion (the portion forming the electrostatic latent image that has been exposed) has a "light portion potential" of -100.

[0035] In this embodiment, the developing roller 41 installed in the developing unit (developing device) 2 contacts the photosensitive member 11 during image formation and performs a developing operation in which the electrostatic latent image formed therein is developed. Incidentally, a voltage source (not shown) for the developing roller 41 applies -350 V as a developing voltage to the developing roller 41, and the toner is transferred from the developing roller 41 to the photosensitive member 11 by the potential difference between the developing roller 41 and the photosensitive member 11, so that the electrostatic latent image is visualized by the toner.

[0036] In this embodiment, the developing roller 41 rotates in the direction opposite to the rotation direction of the photosensitive member 11 , and its surface speed is 1.4 times that of the photosensitive member 11 .

[0037] The toner image formed on the photosensitive member 11 by visualizing (developing) the electrostatic latent image with the developing roller 41 is sent to the contact portion of the transfer roller 51 and is transferred onto the recording material R fed in time with the toner image. Incidentally, in this embodiment, 1000 V is applied as a transfer bias to the transfer roller 51 between the transfer roller 51 and the photosensitive member 11 by a transfer voltage source (not shown).

[0038] Then, the recording material R to which the toner image is transferred is sent to the fixing device 71. In the fixing device 71, heat and pressure are applied to the recording material R, so that the transferred toner image is fixed on the recording material R.

[0039] On the other hand, the transfer residual toner that is not transferred at the transfer portion is removed by the cleaning blade 61. The cleaning blade 61 is installed so that its free end extends toward the upstream side (in the "reverse direction") in the rotation direction Rd of the photosensitive member 11. In addition, the free end of the cleaning blade 61 installed in the reverse direction contacts the photosensitive member 11 with an appropriate pressure, so that the transfer residual toner can be removed from the photosensitive member 11. In addition, the surface of the photosensitive member 11 is charged by the charging roller 21 in a state where no toner or the like is present (the toner or the like is removed).

[0040] By repeating these steps, a toner image is formed on the recording material R. Meanwhile, the toner removed from the photosensitive member 11 by the cleaning blade 61 is stored in the residual toner storage chamber 62. In this embodiment, spherical silica having a diameter of approximately 100 nm is externally added to the toner to minimize transfer residual toner, thereby improving the transfer performance of the toner (image). This prevents contact between the toner base material (base toner particles) and the photosensitive member 11, effectively controlling the toner deposition force on the surface of the photosensitive member 11 and, consequently, improving the transfer performance.

[0041] <Developer Unit>

[0042] Next, the developing unit (developing device) 2 of this embodiment will be described in detail.

[0043] like Figure 2 As shown in FIG, the developing unit (developing device) 2 of this embodiment includes a developing container (frame) 40 and is supported by the developing container (frame) 40 so that a developing roller (developer carrying member) 41 and a toner supplying roller 42 are rotatable. Incidentally, the developing roller 41 is formed in a cylindrical shape so that toner can be carried on its outer peripheral surface.

[0044] The toner supply roller 42 is arranged to contact the outer peripheral surface of the developing roller 41. By the toner supply roller 42, the toner is supplied to the developing roller 41 so that the toner is carried on the surface of the developing roller 41.

[0045] The rotation direction of the developing roller 41 and the toner supply roller 42 is Figure 2The developing roller 41 is a roller prepared by providing a conductive elastic rubber layer having a predetermined volume resistance on the peripheral surface of a core metal, and its surface has a predetermined surface roughness.

[0046] Toner supply roller 42 is a roller prepared by providing a polyurethane foam layer on the peripheral surface of a core metal, and its volume resistance is adjusted to a predetermined value. On the surface layer of this polyurethane foam layer, foam pores are opened, making it easy to hold and feed toner.

[0047] The developing scraper (regulating member) 43 is composed of a flexible elastic plate (e.g., a SUS plate), and one end 431 thereof is fixed to the developing container (frame) 40, and the other end 432 thereof is a free end. The developing scraper 43 is arranged so as to form a contact nip N between itself and the surface of the developing roller 41.

[0048] The toner supplied to the developing roller 41 by the toner supplying roller 42 is regulated by the free end 432 of the developing blade 43 so that a substantially uniform toner coating (not shown) is formed.

[0049] Furthermore, the toner coating is arranged so that the toner is rubbed by the plate (scraper) surface (Z10, Z20) near the free end (other end) 432 of the development blade 43 and by the surface of the conductive elastic rubber layer of the developing roller 41. For this reason, the toner is triboelectrically charged while the toner coating is formed, so that triboelectric charge is imparted to the toner. Incidentally, in this embodiment, the development blade 43 is constructed using a SUS material.

[0050] In order to prevent the toner in the developer unit 2 from leaking outside the developer unit 2, a leakage prevention sheet 44 is attached to the developer container (frame 40) so that the sheet 44 and the developing roller 41 are in contact with each other in an appropriate state, thereby preventing the toner in the developer container 40 from leaking outside the developer container 40. The sheet 44 is a flexible sheet, and in this embodiment, a sheet made of PPS resin and having a thickness of 60 μm is used. The sheet 44 is attached to the developer container 40 with a certain degree of contact pressure to prevent the toner from leaking from the developer container 40.

[0051] In this example, the toner has a central toner particle diameter of 7.0 μm, and silica is used as an external additive. Externally adding silica ensures the toner's fluidity, facilitating the extension of cartridge life and maintaining image quality. Incidentally, the toner's fluidity was measured in this example using a powder tester PT-X manufactured by Hosokawa Micron. The fluidity of the toner used in this example was 50.

[0052] <Relationship between coating and regulating member>

[0053] Next, we will use Figure 1 、 Figure 3 and Figure 4 The developing blade (regulating member) 43 of this embodiment and the relationship between the toner coat and the regulating member are specifically described.

[0054] Figure 1 : is a schematic cross-sectional view (perpendicular to the rotation axis of the developing roller 41 ) showing a state in which the developing blade 43 and the developing roller 41 used in the image forming apparatus of this embodiment are in contact with each other. Figure 3 is a schematic cross-sectional view of the development blade 43 of this embodiment. Figure 4 : is a schematic cross-sectional view showing a modified example (embodiment) of the developing blade 43 of this embodiment.

[0055] like Figure 1 and Figure 3 , in this embodiment, the developing blade 43 is provided at the other end 432 thereof with a contact portion CP which contacts the developing roller 41 and forms a contact nip N between itself and the developing roller 41. Incidentally, the other end 432 of the developing blade 43 is mounted to the developing container (developing device) 40 so as to extend toward the upstream side of the developing roller 41 with respect to the rotation direction Rb.

[0056] In this embodiment, at the contact portion CP, the position O at which the maximum value (contact peak pressure portion P1) of the pressure distribution against the developing roller 41 with respect to the rotational direction Rb of the developing roller 41 is achieved is the reference position. At this time, in the contact portion CP, the surface roughness of the developing blade 43 in the first region Z1 located on the upstream side of the reference position is smaller than the surface roughness of the developing blade 43 in the second region Z1 located on the downstream side of the reference position.

[0057] Incidentally, in this embodiment, the contact portion CP includes a first surface portion Z10 forming the contact nip N and a second surface portion Z20 located on the downstream side of the first surface portion Z10 with respect to the rotation direction Rb, the second surface portion Z20 being connected to the first surface portion Z10 and forming the contact nip N. The first surface portion Z10 and the second surface portion Z20 are flat surfaces Z1p and Z2p, respectively. The first region Z1 is formed at the first surface portion Z10 (Z1p), and the second region Z20 is formed at the second surface portion Z20 (Z2p).

[0058] Specifically, the surface of the developing roller 41 moves (rotates) in the rotation direction Rb. The thickness of the toner coat carried on the surface of the developing roller 41 is controlled (the amount is adjusted) mainly at a position O (contact peak pressure portion) where the pressure (distribution) becomes maximum in the contact nip N where the developing blade 43 and the developing roller 41 are in contact with each other.

[0059] A peak pressure is formed at a portion where the angle and curvature of the developing blade 43 become minimum in the contact nip portion N. For example, at Figure 1 , the contact portion CP of the developing blade 43 is set so that the peak pressure is formed at the angular position O point where the two flat surfaces Z10 and Z20 intersect each other.

[0060] When the angle of the developing blade 43 does not change in the contact nip N (for example, when the contact surface of the developing blade 43 in the contact nip N is a flat surface or when the curvature of the contact surface does not substantially change), a peak pressure is formed at the center of the contact nip N. That is, at Figure 1 , the position of the peak pressure when the angle of the developing blade 43 in the contact nip portion N does not change (when the contact surface of the developing blade 43 in the contact nip portion N is a flat surface) is shown.

[0061] On the other hand, Figure 4 In the modified example (embodiment) shown in , in the case where the cleaning blade 43 causes the curvature of the cleaning blade 43 to change in the contact nip N, a peak pressure is formed at a portion (position O) where the curvature becomes minimum. That is, at Figure 4 In the configuration shown in , the contact peak pressure portion P1 (reference position) is formed at the position O (O position) where the curvature becomes minimum.

[0062] In this embodiment, the contact pressure of the development blade 43 is set to approximately 20 gf / cm.

[0063] Next, control of the surface roughness of the developing blade 43 in the contact nip N in this embodiment will be described.

[0064] like Figure 1As shown in , in this embodiment, the surface roughness of the cleaning blade 43 at the contact portion CP is set to different values ​​between the upstream first region Z1 and the downstream second region Z1 (with the contact peak pressure portion generation position (O position) as the boundary).

[0065] Specifically, if Figure 1 As shown in , in this embodiment, the contact portion CP is composed of a plurality of (two) flat surface portions, and the position (O position) of the contact peak pressure portion is the position where the angle formed by the intersecting (two) flat surfaces becomes the smallest. Incidentally, as Figure 4 As shown in the modified example of , in the case where the contact portion Cp is composed of a curved surface portion instead of a flat surface portion, the position of the contact peak pressure portion is the position (O position) where the curvature becomes minimum.

[0066] Specifically, in this embodiment, Figure 1 As shown in , the roughness changes between the first surface portion Z10 and the second surface portion Z20, and the roughness in the first surface portion Z10 is made smaller than the roughness in the second surface portion Z20. Here, the first surface portion Z10 and the second surface portion Z20 are two flat surfaces constituting the contact portion CP of the development blade 43. The first region Z1 and the second region Z2 are portions located in the contact nip N, and the first region Z1 is a portion of the first surface portion Z10, and the second region Z2 is a portion of the second surface portion Z20.

[0067] The reason why the roughness of the first surface portion Z10 is made small is to suppress image defects as “vertical streaks” due to the developing blade 43 .

[0068] That is, in order to control the toner adjustment amount (thickness of the coating), the first surface portion Z10 constitutes the contact surface until (immediately before) the toner enters the contact peak pressure portion and the toner moves along the first surface portion Z10 in the rotation axis direction (longitudinal direction) of the developing roller 41 until the toner reaches the peak pressure portion CP. Depending on the surface state (particularly the roughness) of the first surface portion Z10, the amount of toner reaching the peak pressure portion CP may not become uniform over the entire area with respect to the rotation axis direction (longitudinal direction) of the developing roller 41 in some cases.

[0069] In this case, the amount of toner immediately before contact peak pressure portion P1 (adjustment) varies with respect to the longitudinal direction, and the amount of toner (coating thickness) after the toner passes through contact peak pressure portion P1 (adjustment) also varies with respect to the longitudinal direction. This can cause image defects such as "vertical streaks." For the reasons described above, in this embodiment, the roughness of first surface portion Z10 is made relatively small so that the toner amount becomes more uniform until the toner reaches contact peak pressure portion P1.

[0070] On the other hand, the reason why the second surface portion Z20 is rougher than the first surface portion Z10 is that triboelectric charges are imparted to the toner by triboelectric charging.

[0071] After the toner amount (coating thickness) is adjusted at the peak pressure portion CP, the toner is triboelectrically charged by contact with the developing blade 43. Accordingly, in order to actively provide an opportunity for contact with the second surface portion Z20, the roughness of the second surface portion Z20 is set to be relatively large.

[0072] When the roughness is small, there is a possibility that the imparting of triboelectric charge to the second surface portion Z20 is not sufficiently performed. In particular, when the image forming apparatus 100 is used in an environment where triboelectric charge is not easily imparted and both the temperature and humidity are high (for example, a temperature of 32° C. and a humidity of 80% RH), when the imparting of triboelectric charge is insufficient, in some cases, a “toner stagnation” phenomenon occurs on the developing blade 43 and the sheet 44 for leakage prevention.

[0073] One of the factors causing the "toner stagnation" phenomenon is believed to be a decrease in the triboelectric charge of the toner. Specifically, when the triboelectric charge of the toner is low, the electrostatic deposition force on the developing roller 41 becomes weak, and thus the toner is easily deposited on another member in contact with the developing roller 41, causing the toner stagnation phenomenon.

[0074] In this case, due to insufficient deposition force, the conditioned toner coating may fall off the surface of the developing roller 41 (hereinafter referred to as "coating drop"), potentially causing image defects. Furthermore, if toner stagnation occurs repeatedly due to toner deposition on another component, there is a risk of toner contamination due to scattering of the deposited toner when the cartridge is removed from the main assembly and replaced. For this reason, in this embodiment, it is necessary to achieve an appropriate triboelectric charge on the toner by relatively increasing the roughness of the developing blade 43 at the second surface portion Z20.

[0075] Therefore, in this embodiment, the surface roughness of the developing blade 43 at the contact portion CP is controlled, with the contact peak pressure portion P1 (the portion where the angle and curvature become minimum) in the contact nip N serving as the boundary. Specifically, the roughness is reduced on the upstream side in the rotational direction Rb of the developing roller 41 (the roughness at the first surface portion Z10 is reduced), while the roughness on the downstream side is increased relative to the upstream side (the roughness at the second surface portion Z20 is increased relative to the roughness at the first surface portion Z10). This suppresses the occurrence of the aforementioned "vertical streaks" phenomenon while imparting an appropriate triboelectric charge to the toner, thereby suppressing coating shedding, contamination due to stagnant toner, and the like.

[0076] In other words, the surface roughness is made relatively small in the first region Z1 on the upstream side of the position (O position) where the contact peak pressure portion P1 is set in the contact nip portion N. As a result, the developer moves more easily in the axial direction (longitudinal direction) of the developer carrying member, so that the developer coating (thickness) is promoted to be uniform with respect to the longitudinal direction.

[0077] At the same time, in the second region Z2 on the downstream side of the position O where the contact peak pressure portion P1 is set, the surface roughness is made relatively large, so that the triboelectric charging effect on the developer is easily promoted. As a result, by controlling the surface roughness of the developing blade 43 in the contact portion CP in the contact nip N, it is easy to achieve an improvement in the uniformity of the developer amount (developer coat) with respect to the longitudinal direction and an improvement in the charging performance of the developer particles contained in the developer coat in a coordinated manner.

[0078] <Assessment>

[0079] Next, by using the developing blade 43 of this embodiment, its performance will be evaluated through the following experiments.

[0080] exist Figure 1 or Figure 3 , the cross-sectional shape of the development blade 43 in this embodiment is shown. The shape of the free end of the development blade 43 of this embodiment is formed by polishing (processing). That is, before processing, the original development blade has a plate shape, and the second surface portion Z20 and the third surface portion Z30 are perpendicular to each other. The intersection (etched portion) of the second surface portion Z20 and the third surface portion Z30 is polished at a desired angle, so that the first surface portion Z10 and the point O (corner portion) are formed.

[0081] Specifically, in this embodiment, Figure 3As shown in FIG, the distance L1 from point O to the flat surface where the third surface portion Z30 is located is set to 50 μm. The distance L2 from point Q, which is the intersection (corner portion) of the third surface portion Z30 and the first surface portion Z10, to the flat surface where the second surface portion Z20 is located is set to 15 μm. The corner portion (etched portion) of the SUS plate material constituting the development blade is polished so that the distances L1 and L2 have the above-mentioned values.

[0082] Furthermore, by changing the polishing roughness for forming the first surface portion Z10 , the shape and roughness of the contact portion CP were changed, and then the following experiment was conducted.

[0083] First, the occurrence of vertical streaking was examined by varying the roughness Rz of the first surface portion Z10 of the developer blade. Specifically, four developer blades were prepared for Experiments 1 to 4, and the roughness Rz at the first surface portion Z10 was measured. The measured values ​​of roughness Rz were 0.12 μm in Experiment 1, 0.21 μm in Experiment 2, 0.23 μm in Experiment 3, and 0.75 μm in Experiment 4. Regarding the roughness Rz at the second surface portion Z20, all measured values ​​were 0.71 μm.

[0084] To measure the roughness Rz, a laser microscope VK-200 manufactured by KEYENCE was used, and measurement was performed using an objective lens with a magnification of 20. By using Rz as the roughness of the development blade, the resistance when the toner and the development blade move relative to each other can be expressed.

[0085] By using the developing blade in the above-described experimental example, the occurrence state of “vertical streaks” and the occurrence state of “toner stagnation” through a paper passing experiment under a high temperature / high humidity environment were verified and evaluated, respectively.

[0086] Table 1 shows the evaluation results of the respective experimental examples.

[0087] Table 1

[0088]

[0089] *1: “EE” is an experimental example.

[0090] *2: “FSPRz” is the roughness Rz at the first surface portion.

[0091] *3: “SSPRz” is the roughness Rz at the second surface portion.

[0092] *4: “VSP” is the vertical streak phenomenon.

[0093] *5: “TS” stands for toner stagnation.

[0094] A: Unrecognizable

[0095] B: Very mild

[0096] C: Mild

[0097] D: Recognizable in normal images

[0098] (E: Obvious image defects)

[0099] As can be understood from Table 1, the roughness Rz on the upstream side of the contact peak pressure portion P1 relative to the rotational direction Rb of the developing roller has an influence on the occurrence of the vertical streak phenomenon. In this embodiment, the roughness Rz at the upstream first surface portion is set to 0.21 μm or less, making it possible to more effectively suppress the occurrence of streaks.

[0100] Next, by changing the roughness at the second surface portion Z20, an experiment similar to the above-described experiment was performed. Incidentally, all values ​​of the roughness at the first surface portion in Experimental Example 1 and Experimental Examples 5, 6, and 7 were 0.12 μm.

[0101] Table 2 shows the evaluation results for each experimental example.

[0102] Table 2

[0103]

[0104]

[0105] *1: “EE” is an experimental example.

[0106] *2: “FSPRz” is the roughness Rz at the first surface portion.

[0107] *3: “SSPRz” is the roughness Rz at the second surface portion.

[0108] *4: “VSP” is the vertical streak phenomenon.

[0109] *5: “TS” stands for toner stagnation.

[0110] A: Unrecognizable

[0111] B: Very mild

[0112] C: Mild

[0113] D: Recognizable in normal images

[0114] (E: Obvious image defects)

[0115] As can be understood from Table 2, when the roughness at the second surface portion Z20 on the downstream side of the contact peak pressure portion P1 with respect to the rotational direction Rb of the developing roller is smaller than the roughness at the first surface portion Z10 on the upstream side of the contact peak pressure portion P1 with respect to the rotational direction Rb of the developing roller, the triboelectric charge imparting performance is degraded, making it easy for toner stagnation to occur. Incidentally, as can be understood from Experimental Example 7, even when the roughness at the downstream side second surface portion Z20 becomes excessively large, there is a tendency for the vertical streak phenomenon to easily occur.

[0116] This is because an increase in contact opportunities, that is, an increase in the roughness of the developing blade is effective for imparting triboelectric charge, but it is considered that when the roughness becomes excessive, there is a possibility of impairment of the flow of the toner after contact portion CP adjustment.

[0117] As a result, the roughness Rz at the second surface portion Z20 is likely to cause vertical streaks unless the roughness Rz is at least 1 / 2 or less of the average particle size of the toner. In this embodiment, the roughness Rz at the second surface portion Z20 is set to 20% or less of the average particle size of the toner, thereby effectively suppressing the occurrence of vertical streaks.

[0118] In this embodiment, the toner has an average particle size (primary average particle size) of 8.0 μm or less. In particular, according to the configuration of this embodiment, further advantageous effects are achieved when forming an image using a developer containing a toner having a relatively small particle size (e.g., a particle size of 5.0 μm or less). Specifically, even with a toner having a relatively small particle size, the configuration of this embodiment facilitates improved uniformity in the amount of developer (coating) on ​​the developing roller while effectively suppressing a reduction in the developer charge due to triboelectric charging.

[0119] As described above, the roughness is controlled with the contact peak pressure portion P1 in the contact nip portion N as a boundary, and the roughness in the first area Z1 on the upstream side of the contact peak pressure portion P1 is made smaller than the roughness in the second area Z2 on the downstream side of the contact peak pressure portion P1, so that the occurrence of vertical stripes and the occurrence of colorant stagnation are easily and coordinately suppressed.

[0120] In addition, similar evaluation experiments were conducted using a toner with low cohesion (i.e., high fluidity) (for example, toner particles containing a sufficient amount of silica as an external additive on their surfaces). When a toner with low cohesion was used, in this embodiment, in Experiments 2, 3, 4, and 7, the results showed that even when the roughness at the first surface portion Z10 was such that vertical streaks occurred, the degree of vertical streaks was suppressed.

[0121] This is because the toner with a low degree of aggregation has less resistance to the roughness of the developing blade, and therefore, a difference (unevenness) in the toner amount with respect to the longitudinal direction, which is a factor causing vertical streaks, is hardly generated.

[0122] On the other hand, regarding triboelectric charge imparting to the toner, triboelectric charge imparting is performed by increasing contact opportunities due to resistance to the developing blade caused by the roughness, and therefore, the roughness in the nip N needs to be increased.

[0123] That is, for example, in a toner with a low degree of cohesion, although the absolute values ​​of the roughness of the first surface portion Z10 and the second surface portion Z20 change, making the roughness at the first surface portion Z10 smaller than the roughness at the second surface portion Z20 makes it easy to suppress both vertical streaks and toner stagnation.

[0124] The surface roughness of the first surface portion Z10 and the surface roughness of the second surface portion Z20 are appropriately adjusted according to the physical properties of the toner. However, by maintaining the relationship as in the present invention, image defects can be easily suppressed. Incidentally, generally, the surface roughness Rz of the first surface portion Z10 can be set within a range of, for example, 0.1 to 1.0 μm. Furthermore, the surface roughness Rz of the second surface portion Z20 can be set within a range of, for example, 0.2 to 2.0 μm.

[0125] Therefore, the roughness of the developer blade in the contact nip portion N is controlled on the upstream and downstream sides with the contact peak pressure portion P1 as the boundary, and the upstream side roughness is made smaller than the downstream side roughness, making it easy to suppress the occurrence of image defects. In particular, according to the configuration of the present invention, it is easy to suppress the occurrence of vertical streaks when the roughness of the developer blade at the contact portion CP is large, and the occurrence of coating peeling due to insufficient triboelectric charge when the roughness of the developer blade at the contact portion CP is small.

[0126] The configuration of the present invention can be summarized as follows. (1) The developing device 2 of the present invention includes a frame 40, a cylindrical developer carrying member rotatably supported by the frame 40 and for carrying a developer T containing toner particles, and a regulating member 43. The regulating member 43 is fixed to the frame 40 at one end 431 and includes a contact portion CP that contacts the developer carrying member 41 at the other end 432 and forms a contact nip N between itself and the developer carrying member 41.

[0127] When the position O of the contact portion CP at which the pressure distribution of the contact portion CP on the developer carrying member 41 relative to the rotation direction Rb of the developer carrying member 41 is the maximum value is the reference position P1, the contact portion includes a first region Z1 located upstream of the reference position P1 relative to the rotation direction Rb and a second region Z2 located downstream of the reference position P1, and the contact portion CP has a surface roughness Rz in the first region Z1 that is smaller than that in the second region Z2, and the surface roughness Rz in the second region Z2 is 20% or less of the average particle size of the colorant particles contained in the developer T.

[0128] As a result, in the contact nip portion N, the surface roughness is relatively low in the first region Z1 upstream of the position where the contact peak pressure is set (the contact peak pressure portion), allowing the developer to easily move in the axial direction (longitudinal direction) of the developer carrying member. Furthermore, uniformity of the developer coating (thickness) relative to the longitudinal direction is promoted. Meanwhile, the surface roughness is relatively high in the second region Z2 downstream of the position where the contact peak pressure is set, promoting triboelectric charging of the developer.

[0129] As a result of this, by controlling the surface roughness at the contact portion in the contact nip, it is easy to enhance the uniformity of the developer coating amount in the contact nip while suppressing a decrease in the chargeability.

[0130] (2) In the developing apparatus of the present invention, the contact portion CP can include a first surface portion Z10 forming the contact nip N, and a second surface portion Z10 located downstream of the first surface portion Z10 with respect to the rotation direction and for connecting to the first surface portion Z10 and for forming the contact nip N. The first region Z1 may be formed at the first surface portion Z10, and the second region Z2 may be formed at the second surface portion Z20.

[0131] That is, the contact portion CP can be provided in a plurality of surface portions. In addition, with respect to the rotation direction Rb, at two portions adjacent to the contact peak pressure portion P1, the first region Z1 may be formed in at least a portion of the first surface portion Z10 located upstream of the contact peak pressure portion P1, and the second region Z1 may be formed in at least a portion of the second surface portion Z10 located downstream of the contact peak pressure portion P1.

[0132] (3) In the developing apparatus of the present invention, both the first surface portion Z10 and the second surface portion Z20 may also be composed of flat surfaces.

[0133] Incidentally, a portion (corner) connecting the first surface portion Z10 and the second surface portion Z20 which are flat surfaces may be appropriately subjected to chamfering.

[0134] (4) In the developing apparatus of the present invention, the first surface portion Z10 and the second surface portion Z20 may also be constituted by a single curved surface CS having no inflection point.

[0135] Incidentally, the curved surface CS may also be formed by connecting a plurality of curved surfaces having different radii of curvature.

[0136] (5) In the developing apparatus of the present invention, the surface roughness Rz in the first zone Z1 may preferably be 0.21 μm or less.

[0137] Thereby, in the contact nip, movement of the developer in the longitudinal direction becomes easier, so that uniformity of the coating is further promoted.

[0138] (6) In the developing apparatus of the present invention, the toner particles may preferably be spherical toner particles having an average particle diameter of 8.0 μm or less.

[0139] Thereby, in the contact nip, the developer can be triboelectrically charged more efficiently.

[0140] (7) In the developing apparatus of the present invention, the other end 432 of the regulating member 43 may be mounted to the frame 40 so as to extend toward the upstream side in the rotational direction Rb of the developer carrying member 41 .

[0141] In the configuration in which the other end (free end) of the regulating member is attached so as to extend toward the upstream side, contact pressure is more easily obtained compared to the configuration in which the other end of the regulating member is attached so as to extend toward the downstream side.

[0142] (8) In the developing apparatus of the present invention, the regulating member 43 may also be provided with the metal blade 43a, and the contact portion CP may also be formed by subjecting the edge portion 43a1 of the metal blade 43a to polishing.

[0143] Incidentally, as a method other than the method of forming the contact portion CP by polishing, control of the shape and surface roughness of the contact portion CP may also be achieved by a method such as sand blasting or surface etching using an etchant.

[0144] (9) In the developing device of the present invention, the developing device 2 may also be constituted to be attachable to and detachable from the apparatus main assembly 100 a of the image forming apparatus 100 .

[0145] (10) The regulating member 43 of the present invention includes a contact portion CP that contacts the rotatable developer carrying member 41 for carrying the developer and is capable of forming a contact nip N between itself and the developer carrying member. Further, the contact portion CP includes a first flat surface Z1p that forms the contact nip N and a second flat surface Z2p that forms the contact nip N and that not only intersects with the first flat surface Z1p but is also connected to the first flat surface Z1p. The first flat surface Z1p is located upstream of the second flat surface Z2p with respect to the rotational direction Rb of the developer carrying member, and the surface roughness Rz in the first flat surface Z1p is smaller than the surface roughness Rz in the second flat surface Z2p.

[0146] (11) The process cartridge 1 of the present invention includes the above-mentioned developing device 2 and an image bearing member 11 for bearing a developer image, and is configured to be mountable in and detachable from the apparatus main assembly 100a of the image forming apparatus 100.

[0147] (12) The image forming apparatus 100 of the present invention includes the above-described developing device 2 or the above-described process cartridge 1 and includes the transfer member 51 .

[0148] According to the present invention, with a simple configuration, it is possible to easily enhance the uniformity of the amount of developer (developer coat) with respect to the longitudinal direction while suppressing a decrease in the chargeability of developer particles contained in the developer coat.

[0149] While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.

Claims

1. A developing device comprising: frame; a cylindrical developer carrying member rotatably supported by the frame and configured to carry a developer containing toner particles; as well as a regulating member fixed at one end thereof to the frame and including a contact portion that contacts the developer carrying member at the other end thereof and forms a contact nip between itself and the developer carrying member, wherein, when the position of the contact portion indicating the maximum value of the pressure distribution of the contact portion on the developer carrying member with respect to the rotational direction of the developer carrying member is a reference position, The contact portion includes: a first surface portion for forming the contact nip portion, a first area being formed at the first surface portion; and A second surface portion for forming the contact nip portion, a second area being formed at the second surface portion, the second surface portion being located downstream of the first surface portion in the rotational direction, and intersecting the first surface portion; wherein the first region is located upstream of the reference position with respect to the rotation direction, and The second region is located downstream of the reference position with respect to the rotation direction, and The contact portion has a smaller surface roughness in the first region than in the second region, and the surface roughness in the second region is 20% or less of an average particle diameter of the toner particles contained in the developer.

2. The developing device according to claim 1, wherein The first surface portion is constituted by a flat surface, and the second surface portion is constituted by a flat surface.

3. The developing device according to claim 1, wherein The first surface portion and the second surface portion are composed of a single curved surface having no inflection point.

4. The developing device according to claim 1, wherein The surface roughness in the first region is 0.21 μm or less.

5. The developing device according to claim 1, wherein The toner particles contained in the developer are spherical toner particles having an average particle diameter of 8.0 μm or less.

6. The developing device according to claim 1, wherein The other end of the regulating member is mounted to the frame so as to extend toward an upstream side in a rotational direction of the developer carrying member.

7. The developing device according to claim 1, wherein The regulating member comprises a metal scraper, and Herein, the contact portion is formed by subjecting an edge portion of the metal scraper to polishing.

8. The developing device according to claim 1, wherein The developing device is mountable in and detachable from a main assembly of the image forming apparatus.

9. An adjusting member comprising: a contact portion that contacts a rotatable developer carrying member for carrying the developer and is capable of forming a contact nip between itself and the developer carrying member, Wherein, the contact portion includes: forming a first flat surface of the contact nip portion; and a second planar surface forming the contact nip, intersecting the first planar surface and connected to the first planar surface, wherein the first flat surface is located upstream of the second flat surface with respect to the rotation direction of the developer carrying member, and The first flat surface has a surface roughness smaller than that of the second flat surface.

10. A process cartridge comprising: The developing device according to claim 1; as well as an image bearing member configured to bear a developer image, Here, the process cartridge is installable in and detachable from a main assembly of an image forming apparatus.

11. An image forming apparatus comprising: The developing device according to claim 1 or the process cartridge according to claim 10; as well as transfer member, Wherein, the image forming device forms an image.

Images