JP2016031406A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming apparatus that can prevent a deterioration in quality of an image due to an external additive in a toner.SOLUTION: The value of loss elastic modulus E" of a cleaning blade 35 is defined as 1.60×10[Pa] to 2.01×10[Pa] when measured at 70°C and 3.60×10[Pa] to 7.70×10[Pa] when measured at 100°C, so as to suppress an event in which an external additive added to a toner passes through a cleaning blade 35 to a degree not affecting the quality of an image to be transferred to a sheet P, and thereby achieving an image forming apparatus that can prevent a deterioration in quality of an image due to the external additive in the toner.SELECTED DRAWING: Figure 8

Description

  The present invention relates to an image forming apparatus, and is suitable for application to, for example, an electrophotographic printer or copying machine.

  In general, in an image forming apparatus such as a copying machine or a printer, after a toner supplied from a supply roller onto a developing roller is adjusted to a uniform thin layer by a regulating blade, the developing roller and the photosensitive drum come into contact with each other. By rotating while approaching, toner adheres to the electrostatic latent image on the photosensitive drum from the developing roller, and the electrostatic latent image is visualized as a toner image. This toner image is transferred onto a medium such as paper by a transfer member such as a roller or a belt. The toner that is not partially transferred and remains on the photosensitive drum is scraped off by a cleaning member that is normally placed in contact with the photosensitive drum. The cleaning member scrapes unnecessary toner remaining on the photosensitive drum by pressing a blade made of an elastic material such as urethane rubber against the photosensitive drum.

  Conventionally, as this cleaning member, an elastic body having various specifications has been used in order to ensure good cleaning properties. One of the characteristics is a loss elastic modulus, and a method for ensuring good cleaning properties for toner by specifying the loss elastic modulus at temperatures (0 degrees and 40 degrees) at which the image forming apparatus is used is proposed. (For example, refer to Patent Document 1).

JP 2006-301273 A

  On the other hand, in recent years, toners are being charged at high speed and fixed at low temperature for the purpose of improving image quality and speed. A plurality of different large amounts of external additives (hereinafter referred to as external additives) are added to such toners for high-speed charging and low-frequency fixing. Since this external additive has a particle size smaller than that of the toner base particles, it may slip through the cleaning member, and this external additive adheres to the charging roller or the like, thereby degrading the quality of the image transferred to the medium. There was something that would let me. As described above, the conventional cleaning member cannot be said to have good cleaning properties with respect to the external additive, and there is a problem that the image quality is deteriorated by the external additive added to the toner.

  The present invention has been made in consideration of the above points, and an object of the present invention is to propose an image forming apparatus capable of preventing deterioration of image quality.

In order to solve this problem, in the present invention, an image carrier on which an electrostatic latent image is formed, a charging member for charging the image carrier, and the image carrier charged by the charging member are externally added. Remaining on the image bearing member, a developing unit that forms a developer image by attaching a developer to which a developer is added, a transfer unit that transfers the developer image formed by the developing unit to a medium, and the like. A cleaning member for removing the developer from the image carrier, and the cleaning member has a loss elastic modulus at a measurement temperature of 100 ° C. of 3.00 × 10 ⁴ [Pa] to 7.70 × 10 ⁴ [Pa]. The elastic body included in the range of

Thus, in the present invention, an elastic body having a loss elastic modulus of 3.00 × 10 ⁴ [Pa] to 7.70 × 10 ⁴ [Pa] at a measurement temperature of 100 ° C. is used as the cleaning member. Thus, the opportunity for the external additive to slip through the cleaning member can be suppressed to such an extent that the quality of the image transferred to the medium is not affected.

  According to the present invention, it is possible to realize an image forming apparatus capable of preventing deterioration in image quality due to an external additive of toner.

1 is a schematic diagram illustrating an overall configuration of an image forming apparatus. It is a basic diagram which shows the structure of a developing device. It is a basic diagram which shows the structure of a cleaning blade. 1 is a block diagram illustrating a block configuration of an image forming apparatus. It is a basic diagram with which it uses for description of the stick-slip movement by a cleaning blade. It is a basic diagram which shows a mode that an external additive slips through a blade nip by stick-slip movement. It is a graph which shows the temperature dependence of a loss elastic modulus. It is a table | surface which shows the relationship between a loss elastic modulus and cleaning property. It is a graph which shows the difference in the loss elastic modulus for every cleaning blade which becomes remarkable at high temperature. 6 is a table showing the relationship between toner chargeability and cleaning properties.

  Hereinafter, modes for carrying out the invention (hereinafter referred to as embodiments) will be described in detail with reference to the drawings.

[1. Overall configuration of image forming apparatus]
FIG. 1 shows the overall configuration of an image forming apparatus 1 that is an electrophotographic printer. As shown in FIG. 1, the image forming apparatus 1 has a substantially box-shaped housing 2. In the following description, the right side in the figure of the housing 2 is the front surface, the left side in the drawing is the rear surface, the direction from the front surface to the rear surface of the housing 2 is the rear direction, the direction from the rear surface to the front surface is the front direction, The direction from the lower side to the upper side of 2 is the upward direction, and the direction from the upper side to the lower side of the housing 2 is the downward direction.

  Inside the housing 2, there are toners (for example, black (K), yellow (Y), magenta (M), and cyan (C) as multi-color developers handled by the image forming apparatus 1. The four developing devices 3K, 3Y, 3M, and 3C corresponding to each of the toners are provided along the conveyance path 4 of the paper P in the front-rear direction. To the four developing devices 3K, 3Y, 3M, and 3C, toner cartridges 5K, 5Y, 5M, and 5C that store toner of each color supplied to the developing devices 3K, 3Y, 3M, and 3C are detachably attached. ing. Detailed configurations of the developing devices 3K, 3Y, 3M, and 3C will be described later.

  Further, an annular transfer belt 6 extending in the front-rear direction along the conveyance path 4 is provided below the four developing devices 3K, 3Y, 3M, and 3C. The transfer belt 6 is driven by the transport rollers 7 and 8 to transport the paper P from the front (upstream in the transport direction) to the rear (downstream in the transport direction). Further, below the transfer belt 6, a paper cassette 9 for storing the paper P is provided. The paper P is fed from the paper cassette 9 to the transport path 4 one by one by the hopping roller 10, transported to the transfer belt 6 by the registration rollers 11, 12 and 13, and passes over the transfer belt 6.

  Further, below each of the four developing devices 3K, 3Y, 3M, and 3C, transfer rollers 14K, 14Y, 14M, and 14C are provided as transfer portions with the upper surface portion of the transfer belt 6 interposed therebetween. It has been. When the paper P passes over the transfer belt 6 by the four transfer rollers 14K, 14Y, 14M, and 14C, the toner images of the respective colors developed by the four developing devices 3K, 3Y, 3M, and 3C are transferred. Is done. A fixing device 17 having a heat roller 15 and a backup roller 16 is provided behind the transfer belt 6 (downstream in the transport direction). The image forming apparatus 1 fixes the toner image on the paper P by the fixing device 17, and then discharges the paper P to the outside by the discharge rollers 18 and 19.

  Furthermore, a control board 20 that controls the operation of each part of the image forming apparatus 1 is provided at the bottom of the housing 2.

[2. Configuration of developing device]
Next, the configuration of the developing devices 3K, 3Y, 3M, and 3C will be described in detail with reference to FIG. The developing devices 3K, 3Y, 3M, and 3C have the same configuration except that the color of the toner to be handled is different. Therefore, only the configuration of the developing device 3K will be described here in order to avoid duplication of description.

  The developing device 3K includes a cylindrical photosensitive drum 30 as an image carrier on which an electrostatic latent image is formed, a developing roller 31 as a developing unit disposed opposite to the photosensitive drum 30, and the developing roller 31. A supply roller 32 that supplies toner and collects unused toner on the developing roller 31; a charging roller 33 that serves as a charging member that charges the photosensitive drum 30; and a regulation blade that forms a thin layer of toner on the developing roller 31 34, a cleaning blade 35 as a cleaning member for scraping off transfer residual toner on the photosensitive drum 30, and an LED exposure unit 36 for forming an electrostatic latent image pattern on the surface of the photosensitive drum 30. Is done. The developing device 3K is detachably attached with a toner cartridge 5K for supplying toner to the developing device 3K. Although not shown, the developing device 3K has a space for storing waste toner scraped off by the cleaning blade 35, and the waste toner stored in this space is conveyed to a waste toner collector. It has become.

  The photosensitive drum 30, the developing roller 31, the supply roller 32, the charging roller 33, and the transfer roller 14K of the developing device 3K rotate in a direction indicated by an arrow in the drawing. Specifically, the photosensitive drum 30 is driven by the main motor 63 (see FIG. 4), the drive is transmitted from the photosensitive drum 30 to the developing roller 31 by a gear (not shown), and further from the developing roller 31 by an idle gear (not shown). The drive is transmitted to the supply roller 32, and each rotates. Further, the charging roller 33 rotates due to friction with the photosensitive drum 30. Further, the transfer belt 6 positioned on the lower side of the developing device 3K is also driven by the main motor 63 (see FIG. 4), and the transfer roller 14K rotates along with the transfer belt 6 in contact therewith.

  The photosensitive drum 30 includes a cylindrical conductive support and a photosensitive layer formed on the surface of the conductive support. The conductive support can be made of, for example, a metal material such as aluminum, aluminum alloy, stainless steel, copper, or nickel, or a resin material to which conductive powder (metal, carbon, tin oxide) is added. . The photosensitive layer is a single photosensitive layer (single-layer type photosensitive layer) in which a photoconductive material is dissolved or dispersed in a binder resin, or a charge generation layer containing a charge generation material and a charge transport layer containing a charge transport material. Can be constituted by a laminated photosensitive layer. The single-layer type photosensitive layer is positively charged and the laminated type photosensitive layer is negatively charged. Here, as an example, a laminated photosensitive layer is used. In the case of a laminated photosensitive layer, an undercoat layer is further formed between the surface of the conductive support and the photosensitive layer. The undercoat layer is obtained by dispersing particles such as metal oxide (for example, titanium oxide) in a binder resin, and is provided to improve adhesion and blocking properties.

  The photosensitive drum 30 is formed by sequentially forming an undercoat layer, a charge generation layer, and a charge transport layer on the surface of a conductive support by, for example, a dip coating method, a spray coating method, or a blade coating method. The Here, a dip coating method is used as an example. In the dip coating method, a conductive support is dipped in a coating solution in which metal oxide particles are dispersed in a solution in which a binder resin (for example, an epoxy resin, a polyethylene resin, etc.) is dissolved. An undercoat layer is formed on the surface of the conductive support by lifting from the coating solution and drying. Next, the conductive support is immersed in a coating solution in which the charge generating material is dispersed in a solution in which a binder resin (for example, polyvinyl butyral resin, polyvinyl formal resin, etc.) is dissolved, and then the conductive support is pulled up from the coating solution. By drying, a charge generation layer is formed on the surface of the undercoat layer. Further, the conductive support is immersed in a coating solution in which a charge transport material is dispersed in a solution in which a binder resin (for example, polyvinyl butyral resin, polyvinyl formal resin, etc.) is dissolved, and then the conductive support is pulled up from the coating solution. By drying, a charge transport layer is formed on the surface of the charge generation layer.

  The LED exposure unit 36 includes, for example, an LED element and a lens array, and is disposed at a position where irradiation light output from the LED element forms an image on the surface of the photosensitive drum 30.

  The developing roller 31 has an elastic layer made of semiconductive urethane rubber formed on the outer periphery of the conductive shaft. This urethane rubber is constituted by dispersing an electronic conductive agent such as carbon black or a conductive filler or an ionic conductive agent as a conductivity imparting agent in order to obtain conductivity. In this embodiment, as an example, an elastic layer having an outer diameter of 19.6 [mm], a hardness of 77 [°], and a partial resistance of 20 [MΩ] is used. The hardness was measured using Asker C (manufactured by Kobunshi Keiki Co., Ltd.). In addition, the value of the partial resistance is such that ball bearings having an outer diameter of 6 [mm] and a width of 1.5 [mm] are disposed at six locations at equal pitches in the axial direction of the developing roller 31. It is an average value of resistance values measured at six locations when a voltage of DC 100 [V] is applied to the surface of the developing roller 31 with a pressure of 20.0 [gf] and applied with a conductive shaft. .

  The supply roller 32 has an elastic layer made of semiconductive foamed silicon rubber formed on the outer periphery of the conductive shaft. In this embodiment, as an example, an elastic layer having an outer diameter of 15.6 [mm], a hardness of 57 [°], and a partial resistance of 30 [MΩ] is used. As the foamed silicone rubber for the elastic layer, various synthetic rubbers such as dimethyl silicone rubber and methylphenyl silicone rubber are added with reinforcing silica filler, vulcanizing agent necessary for vulcanization and curing, and foaming agent. . The hardness was measured using Asker F (manufactured by Kobunshi Keiki Co., Ltd.).

  The charging roller 33 has a conductive elastic layer formed on the outer periphery of a metallic shaft. This elastic layer is an ion conductive rubber elastic layer mainly composed of Iupychlorohydrin rubber (ECO), and the surface treatment is performed by infiltrating the surface treatment liquid containing an isocyanate (HDI) component on the surface thereof. As a result, the contamination resistance of the photosensitive drum 30 and the releasability of the toner and its external additives are obtained.

  The regulation blade 34 is made of SUS, and a bending process is applied to a contact portion with the developing roller 31. In the present embodiment, as an example, the plate thickness is 0.05 [mm], the radius of curvature of the bent portion subjected to the bending process is 0.5 [mm], and the tenacity is 0.6 in terms of 10-point average roughness. [μm] was used.

  As shown in FIG. 3A in addition to FIG. 2, the cleaning blade 35 is arranged in parallel with the rotation axis of the photosensitive drum 30, and the root portion is in contact with the surface of the photosensitive drum 30. Is fixed to the frame of the developing device 3K through a rigid blade holder 40. The cleaning blade 35 contacts the surface of the photosensitive drum 30 at a position downstream of the transfer roller 14K in the rotational direction of the photosensitive drum 30 and upstream of the charging roller 33 in the rotational direction of the photosensitive drum 30. It is like that.

  The cleaning blade 35 has a so-called plate shape with a rectangular cross section perpendicular to the longitudinal direction (the axial direction of the photosensitive drum 30), and a corner portion of the tip portion comes into contact with the surface of the photosensitive drum 30. Thus, it is elastically deformed by being pressed against the surface of the photosensitive drum 30. At this time, as shown in FIG. 3B, which is an enlarged view of the contact portion between the photosensitive drum 30 and the cleaning blade 35, the corner portion of the tip portion of the cleaning blade 35 is elastically deformed so as to be crushed. In surface contact with the surface of the photosensitive drum 30. A contact portion 41 of the cleaning blade 35 with the photosensitive drum 30 is referred to as a blade nip 41. The cleaning blade 35 rotates on the surface of the photoconductive drum 30 when the photoconductive drum 30 rotates while the corner portion of the tip portion is elastically deformed and is in surface contact with the surface of the photoconductive drum 30. The remaining toner is scraped off at the tip.

  The cleaning blade 35 is made of an elastic body such as urethane rubber, epoxy rubber, acrylic rubber, fluororesin rubber, nitrile butadiene rubber (NBR), styrene butadiene rubber (SBR), isoprene rubber (IR), or polybutadiene rubber. In the present embodiment, urethane rubber is used as an example. In this embodiment, as an example, the cleaning blade 35 having a free end length L of 7.7 [mm] and a thickness T of 1.8 [mm] is used. The free end is a portion of the entire cleaning blade 35 that protrudes from the blade holder 40 and can be deformed. In the image forming apparatus 1 of the present embodiment, the length L is, for example, 7.5. The thickness T is specified in the range of 1.5 to 2.0 [mm], for example, in the range of ~ 8.0 [mm].

  Furthermore, in the image forming apparatus 1 according to the present embodiment, the cleaning angle θ1 of the cleaning blade 35 is defined to be, for example, 10.3 degrees to 14.7 degrees. The cleaning angle θ1 is an angle formed between the tangential direction of the surface of the photosensitive drum 30 at the contact point between the photosensitive drum 30 and the cleaning blade 35 and the generatrix direction of the cleaning blade 35 (this is referred to as an initial set pressure contact angle). This is a value obtained by subtracting an angle (referred to as a blade displacement angle) θ4 formed by a tangential direction at the deformation start point of the cleaning blade 35 and a generatrix direction of the cleaning blade 35 from θ2. Furthermore, in the image forming apparatus 1 of the present embodiment, the linear pressure (that is, the pressing force) W that presses the cleaning blade 35 against the surface of the photosensitive drum 30 is regulated to, for example, 12 to 24 [gf / cm]. .

  The developing device 3K has such a configuration, and the developing devices 3Y, 3M, and 3C have the same configuration. Here, the configuration of the toner supplied to each of the developing devices 3K, 3Y, 3M, and 3C will also be described. The toner supplied to each of the developing devices 3K, 3Y, 3M, and 3C has the same basic configuration except that the colors are different.

  The toner is obtained by adding an additive (external additive) such as an inorganic fine powder or an organic fine powder to the outside of the toner base particles containing at least a binder resin. The binder resin is not particularly limited, but is preferably a polyester resin, a styrene-acrylic resin, an epoxy resin, or a styrene-butadiene resin. In addition, a release agent, a colorant, and the like are added to the binder resin, and additives such as a charge control agent, a conductivity modifier, a fluidity improver, or a cleaning property improver are appropriately added. It may be added.

  The release agent added to the binder resin is not particularly limited, but aliphatic carbonization such as low molecular weight polyethylene, low molecular weight polypropylene, olefin copolymer, microcrystalline wax, paraffin wax, and Fischer-Tropsch wax. Oxides of aliphatic hydrocarbon waxes such as hydrogen wax, polyethylene oxide wax, or block copolymers thereof, waxes based on fatty acid esters such as carnauba wax and montanate wax, deoxidized carnauba wax Known ones such as those obtained by partially or entirely deoxidizing fatty acid esters such as The content of the release agent is effectively 0.1 to 20 (parts by weight), preferably 0.5 to 12 (parts by weight) with respect to 100 (parts by weight) of the binder resin. It is also preferable to use a plurality of waxes in combination.

  The colorant to be added to the binder resin is not particularly limited, but dyes, pigments and the like conventionally used as colorants for black, yellow, magenta and cyan toners may be used alone or in combination. For example, carbon black, iron oxide, phthalocyanine blue, permanent brown FG, brilliant first scarlet, pigment green B, rhodamine-B base, solvent red 49, solvent red 146, pigment blue 15: 3, solvent Blue 35, quinacridone, carmine 6B, disazo yellow and the like. The content of the colorant is 2 to 25 (parts by weight), preferably 2 to 15 (parts by weight) with respect to 100 (parts by weight) of the binder resin.

  As the charge control agent added to the binder resin, known ones can be used. For example, in the case of a positively chargeable toner, a quaternary ammonium salt charge control agent, and in the case of a negatively chargeable toner, an azo complex charge control agent, a salicylic acid complex charge control agent, a calixarene charge control agent, etc. Is mentioned. The content of the charge control agent is 0.05 to 15 (parts by weight), preferably 0.1 to 10 (parts by weight) with respect to 100 (parts by weight) of the binder resin.

  The external additive added to the outside of the toner mother flow element is added for the purpose of improving environmental stability, charging stability, developability, fluidity, and storage stability, and known ones can be used. . The content of the external additive is 0.01 to 10 (parts by weight), preferably 0.05 to 8 (parts by weight) with respect to 100 (parts by weight) of the binder resin. In the present embodiment, as external additives, toner base particles are 1 [kg] (100 (parts by weight)) and hydrophobic silica R972 (manufactured by Nippon Aerosil Co., Ltd., average particle size 16 [nm]) is used. 0 (parts by weight) and 0.3 (parts by weight) of melamine resin fine particle posters (manufactured by Nippon Shokubai Co., Ltd., average particle size 0.2 [μm], charge amount +212 [μC / g]) And stirred for 3 minutes.

  In this embodiment, the circularity of the toner base particles is regulated to 0.980 or less (preferably 0.950 to 0.980), and the fluidity of the toner that is an aggregate of the toner base particles is set to 50 to 50. It is defined as 100 [%]. The circularity is a value representing the circularity, and can be represented by the circumference of a circle having the same area as the particle projection area / the circumference of the particle projection image. It shows that there is. This circularity was measured using FPIA-3000 manufactured by Sysmex Corporation. The fluidity is a value representing the liquidity of the toner. As a value related to the fluidity, there is an agglomeration degree, and the agglomeration degree is a ratio that becomes lumpy when vibrated on a sieve having a predetermined opening. A relational expression of fluidity = 100−aggregation degree holds between the fluidity and the aggregation degree. The fluidity was determined from the degree of aggregation measured using a powder tester manufactured by Hosokawa Micron Corporation. The configuration of the toner supplied to each of the developing devices 3K, 3Y, 3M, and 3C is as described above.

[3. Block configuration of image forming apparatus]
Next, the block configuration of the image forming apparatus 1 will be described with reference to FIG. The image forming apparatus 1 is controlled by the printer control unit 50. The printer control unit 50 is connected to an interface unit 52 that receives print data from a host device 51 such as a personal computer, a RAM 53 as a work memory, and a ROM 54 that stores various control programs. The printer control unit 50 includes a calculation unit 55 that performs various calculations.

  Further, a power supply control unit 56 is connected to the printer control unit 50. Based on the control of the printer control unit 50, the power control unit 56 supplies the supply roller 32 from the supply roller bias power source 57, the developing roller bias power source 58, the charging roller bias power source 59, the regulating blade bias power source 60, and the transfer roller bias power source 61. Each bias voltage applied to the developing roller 31, the charging roller 33, the regulating blade 34, and the transfer roller 14 (14A to 14D) is set and changed. Further, a motor driver 62 is connected to the printer control unit 50. The motor driver 62 controls the rotation of the photosensitive drum 30 by driving the main motor 63 based on the control of the printer control unit 50. Further, an LED exposure control unit 64 is connected to the printer control unit 50. The LED exposure control unit 64 controls the operation of the LED exposure unit 36 based on the control of the printer control unit 50. In addition to these, the printer control unit 50 performs density correction, image processing, medium (paper) conveyance control, fixing control, and the like, which are omitted here. The block configuration of the image forming apparatus 1 is as described above. Note that a printer control unit 50, a power supply control unit 56, and the like are mounted on the control board 20 (see FIG. 1).

[4. Printing process by image forming apparatus]
Next, a printing process by the image forming apparatus 1 will be described. This printing process is performed by the printer control unit 50 of the image forming apparatus 1 in cooperation with each unit. The printing process includes a transfer process in which toners of four colors of black, yellow, magenta, and cyan are transferred to the paper P. However, the transfer process of each color is the same, and in order to avoid duplication of explanation, it is described here. Only the black transfer process will be specifically described.

  The printer control unit 50 applies a voltage of −1000 [V] to the charging roller 33, and uniformly charges the surface of the photosensitive drum 30 to −500 V by the charging roller 33. Further, the printer control unit 50 sends image data based on the print data to the LED exposure control unit 64. The LED exposure control unit 64 controls the light emission of the LED exposure unit 36 based on the image data, so that an electrostatic latent image of −50 [V] corresponding to the black print pattern is formed on the surface of the photosensitive drum 30. Form. Then, the printer control unit 50 supplies a toner (black) onto the developing roller 31 by applying a voltage of −300 [V] to the supply roller 32. The toner on the developing roller 31 is thinned by being charged to about −25 [μC / g] by friction with the regulating blade 34 or the like. Further, the printer control unit 50 applies a voltage of −200 [V] to the developing roller 31 to develop the electrostatic latent image on the photosensitive drum 30 with toner to form a toner image. Thereafter, the printer control unit 50 applies a voltage of +2000 [V] to the transfer roller 14K, thereby transferring the toner image formed on the photosensitive drum 30 onto the paper P. The toner remaining on the photosensitive drum 30 after the transfer is scraped off by the cleaning blade 35. The yellow, magenta, and cyan toner images are sequentially transferred onto the paper P in a transfer process similar to the black transfer process.

  Since the toner image transferred onto the paper P is only attached on the paper P with only a weak electrostatic force, the toner image is fixed on the paper P by heating, melting and pressing with the fixing device 17. Thereafter, the paper P is discharged to the outside of the image forming apparatus 1. The printing process of the image forming apparatus 1 is as described above. This printing process is an example in which negatively charged toner is used. When positively charged toner is used, a positive voltage is applied to the charging roller 33 and the developing roller 31. A negative voltage is applied to the transfer roller 14K.

  In such a series of printing processes, the cleaning blade 35 will be described later with respect to the toner base particles remaining on the photoconductive drum 30 while being in contact with the photoconductive drum 30 and the external additive peeled from the toner base particles. Scraping while repeating stick-slip motion. The stick-slip motion is a phenomenon that always occurs when an elastic body is used for the cleaning blade 35, and the image forming apparatus 1 uses this phenomenon to ensure good cleaning properties.

[5. Stick-slip motion]
Here, the stick-slip motion will be described in more detail with reference to FIG. FIG. 5 is an enlarged view of the contact portion between the photosensitive drum 30 and the cleaning blade 35 as compared with FIG. FIG. 5A shows a state immediately after the photosensitive drum 30 starts to rotate in the direction indicated by the arrow Ar1, and at this time, the corner of the tip portion of the cleaning blade 35 is elastically deformed so as to be crushed. The blade nip 41 is formed in surface contact with the surface of the photosensitive drum 30.

  Thereafter, when the photosensitive drum 30 continues to rotate in the same direction, the surface of the photosensitive drum 30 also continues to move in the direction indicated by the arrow Ar1. At this time, the blade nip 41 of the cleaning blade 35 follows the movement of the surface of the photosensitive drum 30 by the frictional force with the surface of the photosensitive drum 30 as shown in FIG. And moved in the direction indicated by the arrow Ar2 in the same direction. Thus, the movement in which the blade nip 41 is pulled and moved in accordance with the movement of the surface of the photosensitive drum 30 is called a stick movement. At this time, an elastic force is exerted on the cleaning blade 35 to return to the original shape. At this time, the static friction force acting on the blade nip 41 is still larger than the elastic force, so the blade does not return to the original shape. The nip 41 is pulled.

  After that, as the blade nip 41 is pulled, the elastic force of the cleaning blade 35 increases, and at a certain point, the static frictional force and the elastic force balance, and the blade nip 41 becomes the surface of the photosensitive drum 30. Slip against. At this time, the frictional force acting on the blade nip 41 changes from a static frictional force to a dynamic frictional force. Since the dynamic friction coefficient is smaller than the static friction coefficient, at this time, the elastic force of the cleaning blade 35 is larger than the frictional force with the surface of the photosensitive drum 30. As a result, as shown in FIG. 5C, the blade nip 41 moves in the direction indicated by the arrow Ar3 opposite to the arrow Ar2 while sliding on the surface of the photosensitive drum 30, and returns to the original position. The cleaning blade 35 returns to its original shape. The movement of the pulled blade nip 41 sliding on the surface of the photosensitive drum 30 and returning to the original position is referred to as a slip movement. A series of operations by the stick motion and the slip motion is called a stick-slip motion. In the printing process, since the photosensitive drum 30 continues to rotate, the cleaning blade 35 repeats this stick-slip motion many times.

  Next, a phenomenon in which the external additive slips through the cleaning blade 35 will be described with reference to FIG. FIG. 6 is also an enlarged view of a contact portion between the photosensitive drum 30 and the cleaning blade 35. As shown in FIG. 6A, in the printing process, the toner base particles 70 and the external additive 71 before being scraped off are damped to the surface of the photosensitive drum 30 by the cleaning blade 35, whereby the photosensitive drum 30 always exists in the vicinity of the blade nip 41 on the upstream side in the rotational direction. As shown in FIG. 6A, generally, the external additive 71 is sufficiently smaller than the toner base particles 70. Incidentally, due to the nature of the electrophotographic printing process, impurities such as paper dust and dust in the air that are larger than the toner base particles 70 may be mixed, but they are omitted here.

  As shown in FIG. 6B, the toner base particles 70 and the external additive 71 are used together with the toner nip 41 when the blade nip 41 of the cleaning blade 35 is pulled on the surface of the photosensitive drum 30 by the stick movement. The surface of the photosensitive drum 30 is moved. Further, as shown in FIG. 6C, when the toner base particles 70 and the external additive 71 are slipped, the blade nip 41 of the cleaning blade 35 slides on the surface of the photosensitive drum 30 and returns to the original position. Then, it is pushed by the cleaning blade 35 and pushed back to the original position against the movement of the surface of the photosensitive drum 30. When the blade nip 41 slides on the surface of the photosensitive drum 30 and returns to the original position by this slip movement, the external additive 71 smaller than the toner base particles 70 is separated from the blade nip 41 and the surface of the photosensitive drum 30. May slip through the space.

  The slipped external additive 71 adheres to the charging roller 33, the developing roller 31, and the like located downstream of the cleaning blade 35 in the rotation direction of the photosensitive drum 30, thereby degrading image quality and the life of the image forming apparatus 1. Cause a decline. In recent years, as the speed of the image forming apparatus 1 is increased, the rotational speed of the photosensitive drum 30 is increased, and the amount of the external additive 71 is increased in order to secure the chargeability of the toner in a short time. The importance of cleaning the additive 71 is increasing.

  Therefore, in the present embodiment, the loss elastic modulus of the cleaning blade 35 is defined by the value at the time of high temperature measurement of 70 ° C. or higher, thereby ensuring good cleaning properties for the external additive. The loss elastic modulus represents the liquid component (viscous component) of the elastic body, and is used as an index indicating the flexibility of the elastic body together with the storage elastic modulus representing the solid component (elastic component) of the elastic body. One of the indices indicating the flexibility of the elastic body is the loss tangent, where the loss tangent is tan δ, the loss elastic modulus is E ″, and the storage elastic modulus is E ′. The loss tangent is tan δ = E ″ / E ′. Can be represented. That is, the loss tangent tan δ is represented by the ratio of the loss elastic modulus E ″ and the storage elastic modulus E ′. When the value is larger than 1, the elastic body is more liquid (that is, the viscosity is strong), A value less than 1 means more solid (ie, more elastic).

  It has been found that the moving distance of the blade nip 41 in the stick-slip motion, that is, the deformation amount of the cleaning blade 35 increases as the loss tangent tan δ increases (Nippon Imaging Society, Vol140, No.4, PP320-329). (2001)). Therefore, the larger the loss elastic modulus E ″, the larger the deformation amount of the cleaning blade 35 in the stick-slip motion. If the rotational speed of the photosensitive drum 30 is constant, the number of stick-slip motions per unit time. Thus, if the number of stick-slip motions can be reduced, the opportunity for the external additive to slip through the cleaning blade 35 can be reduced accordingly, and as a result, the external additive can be reduced. Therefore, if the elastic body having a large loss elastic modulus E ″ is used for the cleaning blade 35, it is possible to ensure good cleaning properties for the external additive.

  On the other hand, the loss elastic modulus E ″ is temperature-dependent and varies depending on the measurement temperature. FIG. 7 is a graph showing the temperature dependency of the loss elastic modulus E ″. As shown in FIG. 7, the loss elastic modulus E ″ changes such that the value is larger as the measurement temperature is lower and the value is smaller as the measurement temperature is higher.

[6. Evaluation of cleaning properties]
Here, a plurality of image forming apparatuses 1 having cleaning blades 35 having different loss elastic moduli E ″ are prepared, and the evaluation results on the cleaning performance with respect to the external additive when the printing test is performed on each of them are shown in FIG. The cleaning blade 35 used was prepared by adjusting the high molecular weight component of the elastic body, and prepared seven types A to G. The loss elastic modulus E ″ was D6100 (Hitachi High-Tech Science Co., Ltd.). The measurement was performed using

  In this printing test, the surrounding environment is kept constant at a temperature of 25 ° C. and humidity of 50%, and printing with a printing duty of 20% is continuously performed on 20000 sheets of paper, and the external additive adhered to the surface of the charging roller 33 every 5000 sheets. The amount of contamination was confirmed, and the contamination level was classified into three levels, ◎, ○, and ×. Here, ◎ indicates that the external additive is not attached at all and the quality of the image is good and the contamination level is the lowest, and ○ indicates that the external additive is attached in a small amount but affects the image quality. The image quality is not good, and the contamination level is the second lowest after ◎, x means that the external additive has adhered so much that the image quality is seriously affected, the image quality is poor, and the contamination level Represents the highest state. In this printing test, the evaluation of the cleaning property with respect to the external additive is evaluated as NG, that is, the good cleaning property with respect to the external additive, with respect to the cleaning blade 35 in which the contamination level becomes x before printing 20000 sheets. It was determined that could not be obtained. Note that the printing duty represents a printing rate when the so-called solid printing in which the LED head of the LED exposure unit 36 is fully exposed to transfer the toner onto the entire sheet P is 100%. The reason why the number of printed sheets is 20000 in this printing test is that the replacement standard for the developing devices 3K, 3M, 3Y, and 3C is set to 20000.

  In the table shown in FIG. 8, the type of the cleaning blade 35 and the loss elastic modulus E ″ measured with the cleaning blade 35 heated to 25 ° C., 40 ° C., 70 ° C., and 100 ° C. in order from the left side for every 5000 sheets. The contamination level of the attached charging roller 33 by the external additive and the evaluation of the cleaning property for the external additive are described. Here, the loss elastic modulus E ″ is 25 ° C., 40 ° C., 70 ° C., 100 ° C. The reason for measuring at different temperatures is that, as described above, the loss elastic modulus E ″ changes with temperature.

  Referring to the table of FIG. 8, between the value of the loss elastic modulus E ″ measured at 70 ° C. and 100 ° C. and the contamination level, the contamination level decreases as the value of the loss elastic modulus E ″ increases. Therefore, it can be said that there is a correlation. From this result, it can be seen that the greater the loss elastic modulus E ″, the smaller the number of stick-slip motions and the smaller the amount of external additive adhering to the charging roller 33 and the lower the contamination level. It can be seen that there is no correlation between the value of the loss elastic modulus E ″ measured at a temperature of 40 ° C. over 40 ° C. and the level of contamination of the charging roller 33 by the external additive.

  Thus, during continuous printing at a room temperature of 25 ° C., the reason why a correlation is obtained between the loss elastic modulus E ″ and the level of contamination by external additives at 70 ° C. to 100 ° C., which is about 50 ° C. higher than the room temperature, is as follows. The local temperature of the blade nip 41, which is the contact portion of the cleaning blade 35 with the photosensitive drum 30, is much higher than the room temperature (that is, the operating temperature of the image forming apparatus 1) due to friction with the photosensitive drum 30 70. It can be assumed that the temperature rises to about 100 ° C to 100 ° C.

  Here, in FIG. 9, among the cleaning blades A to G used in the printing test, the loss elastic modulus E ″ of the cleaning blade B whose cleaning property evaluation was OK and the cleaning blade E whose evaluation was NG was shown. 9 shows that the loss elastic modulus E ″ of the cleaning blades B and E has almost no difference at a temperature lower than 70 ° C., and the difference increases when the temperature exceeds 70 ° C. I understand. For this reason, it is difficult to accurately evaluate the cleaning property only with the loss elastic modulus E ″ measured at a temperature of 25 ° C., for example. In order to accurately evaluate the cleaning property, the loss elastic modulus of at least 70 ° C. or more is required. E "is required.

  For these reasons, in order to ensure good cleaning properties for the external additive, the loss elastic modulus E ″ of the cleaning blade 35 is set under the operating temperature (for example, about 30 ° C.) of the image forming apparatus 1 as in the past. It is understood that the value should not be defined by the measured value, but should be defined by a value measured at a high temperature of at least 70 ° C. higher than the use temperature.

And actually, according to the printing test, as shown in FIG. 8, the loss elastic modulus E ″ at 70 ° C. is in the range of 1.60 × 10 ⁵ [Pa] to 2.01 × 10 ⁵ [Pa]. In addition, the cleaning blades A to D having the loss elastic modulus E ″ at 100 ° C. in the range of 3.60 × 10 ⁴ [Pa] to 7.70 × 10 ⁴ [Pa] are judged to be OK in the cleaning property evaluation. It was done. Although not shown in the table of FIG. 8, when the loss elastic modulus E ″ exceeds 2.01 × 10 ⁵ when measured at 70 ° C., the liquid characteristic (ie, viscosity) of the cleaning blade 35 becomes strong. Thus, the phenomenon that the cleaning blade 35 is turned by friction with the photosensitive drum 30 (this is called blade turning) occurs and the cleaning property is remarkably lowered. Similarly, the loss elastic modulus E ″ is measured at 100 ° C. Even when it exceeded 7.70 × 10 ⁴ , the blade turned up and the cleaning property was remarkably deteriorated. From this, the loss elastic modulus E ″ of the cleaning blade 35 is 1.60 × 10 ⁵ [Pa] or more when measured at 70 ° C., 2.01 × 10 ⁵ [Pa] or less and 3. It can be seen that if it is defined as 60 × 10 ⁴ [Pa] or more and 7.70 × 10 ⁴ [Pa] or less, it is possible to secure a good cleaning property for the external additive while preventing the occurrence of turning of the blade. In the embodiment, by defining the loss elastic modulus E ″ of the cleaning blade 35 in this way, a good cleaning property for the external additive is ensured.

  By the way, in the present embodiment, the loss elastic modulus E ″ is defined by the value at the time of 70 ° C. measurement and the value at the time of 100 ° C. measurement. This is because it can be estimated that the nip 41 is raised to about 70 ° C. to 100 ° C. during actual printing. On the other hand, the loss elastic modulus E ″ is measured only at the value measured at 70 ° C. or measured at 100 ° C. You may make it prescribe | regulate only by the value of time. In this case, as shown in FIG. 9, the difference in the loss elastic modulus E ″ for each cleaning blade 35 is larger when measuring at 100 ° C. than when measuring at 70 ° C. Therefore, if one of the values measured at 70 ° C. and the value measured at 100 ° C. is specified, it is preferable to specify the value measured at 100 ° C. In recent years, considering that the rotational speed of the photosensitive drum 30 is increased with the increase in the speed of the image forming apparatus 1 and the local temperature of the blade nip 41 is likely to rise, the temperature is 100 ° C. higher than that measured at 70 ° C. It can be said that the loss elastic modulus E ″ can be defined at a temperature closer to the actual temperature of the blade nip 41 by defining the value at the time of measurement.

  In addition, if it prescribes | regulates with both the value at the time of 70 degreeC measurement and the value at the time of 100 degreeC measurement like this Embodiment, it prescribes | regulates only with the value at the time of 70 degreeC measurement or only the value at the time of 100 degreeC measurement. Compared to the case, good cleaning properties can be ensured more reliably. For example, it is assumed that there is a cleaning blade 35 having a loss elastic modulus E ″ such that the value at the time of 70 ° C. measurement is within the above-mentioned specified range but the value at the time of 100 ° C. measurement is outside the above-mentioned specified range. Here, if the loss elastic modulus E ″ is defined only by, for example, a value measured at 70 ° C., it is determined that the cleaning blade 35 has good cleaning properties. When the temperature is about 100 ° C., cleaning failure occurs. Therefore, in order to ensure a good cleaning property more reliably, it is desirable to define the loss elastic modulus E ″ of the cleaning blade 35 by both the value at the time of measuring 70 ° C. and the value at the time of measuring 100 ° C.

  Next, using the cleaning blade B for which the evaluation of the cleaning property is determined to be OK in the above-described printing test and the cleaning blade E for which the evaluation is determined to be NG, which cleaning property is evaluated depending on the charging property of the toner. FIG. 10 shows the result of verification as to how it changes. In this verification, five types of different toners such as −5, −10, −25, −50, and −70 (all units are [μC / g]) on the developing roller 31 are prepared, A test similar to the printing test described above was performed for each toner. Each toner has a charge amount adjusted by changing only the amount of the charge control agent added to the inside of the toner base particles. Note that the above-described printing test was performed using a toner having a charge amount of −25 [μC / g] which is generally widely used.

  According to this verification, in the cleaning blade B, it was determined that the cleaning property evaluation was OK with three types of toners with the charge amounts of −10, −25, and −50. The evaluation of the cleaning property was judged to be OK only with one type of toner having an amount of −50. From this result, it can be seen that the cleaning blade B has a wider range of toner charge amount, which is one of the conditions for obtaining good cleaning properties. However, in both cases, when the charge amount was −5 [μC / g], which was the lowest, and when it was −70 [μC / g], which was the highest, the evaluation of the cleaning property was determined to be NG.

  The reason why the toner was NG when the charge amount of the toner was as low as −5 [μC / g] was that the transferability and fog of the toner deteriorated, and as a result, the amount of waste toner reaching the cleaning blade 35 increased. This is considered to be because the cleaning could not be performed efficiently. Actually, when the charge amount of the toner is low, the toner charged with the opposite polarity to the original charge (this is called the opposite polarity toner) increases. The reverse polarity toner in the toner image formed on the photosensitive drum 30 by the LED exposure unit 36 has the same polarity (eg, positive) as the voltage applied to the transfer roller 14 during the transfer process. Therefore, it moves in a direction in which it is pressed against the photosensitive drum 30 instead of the paper P, contrary to the original aim. The reverse polarity toner remains on the photosensitive drum 30 without being transferred in the transfer process, becomes residual transfer toner, and moves to the cleaning blade 35. Further, the reverse polarity toner on the developing roller 31 adheres to an unexposed portion on the photosensitive drum 30 (referred to as a non-exposed portion), which also remains on the photosensitive drum 30 for cleaning. Move to blade 35. Thus, when the charge amount of the toner is low, the amount of waste toner that reaches the cleaning blade 35 is increased, and the cleaning property is deteriorated. The cleaning blade E is judged to have a cleaning property evaluation of OK only when the toner charge amount is −50 [μC / g]. This is because the toner charge amount is −25 [μC / g]. This is probably because the amount of waste toner has decreased.

  The reason why the toner becomes NG when the charge amount of the toner is as high as −70 [μC / g] is considered to be due to the occurrence of highly charged stains. Highly charged dirt means that the surface potential of the toner layer exceeds the surface potential of the non-exposed portion of the photosensitive drum 30 due to an increase in the charge of the toner layer on the developing roller 31. Is a phenomenon that moves. When this highly charged stain occurs, the entire surface is always printed, so that the cleaning property is deteriorated.

  As described above, if the toner charge amount is too low or too high, the cleaning property is deteriorated, but in any case, the cleaning has a loss elastic modulus E ″ at a high temperature of 70 ° C. or more within a specified range. Blade B has a range of toner charge amount that is one of the conditions for obtaining better cleaning performance than cleaning blade E in which loss elastic modulus E ″ at a high temperature of 70 ° C. or higher is outside the specified range. It is understood that is wide.

[7. Summary and Effect]
As described so far, in the present embodiment, it can be assumed that the local temperature of the blade nip 41 during actual printing rises to about 70 ° C. to 100 ° C. Therefore, the loss elastic modulus E ″ of the cleaning blade 35 The value when measured at 70 ° C. is 1.60 × 10 ⁵ [Pa] to 2.01 × 10 ⁵ [Pa], and the value when measured at 100 ° C. is 3.60 × 10 ⁴ [Pa] to 7.70 ×. was defined as 10 ⁴ [Pa]. in the image forming apparatus 1, a cleaning blade 35, by which to use a resilient member of the loss modulus E "satisfying this provision, as in the prior art loss modulus E Compared with the case where “is defined by the operating temperature (about 30 ° C.) of the image forming apparatus 1, the cleaning blade 35 determines the number of stick-slip motions per unit time by the cleaning blade 35. Me can be reliably reduced to the extent that does not cause, the result can be suppressed to the chance of external additive will slip through the cleaning blade 35, to the extent not affecting the quality of the printed image.

  Thus, the image forming apparatus 1 can prevent deterioration of the image quality due to the external additive of the toner, and can maintain a high-quality image for a longer period of time than in the past. In addition, the image forming apparatus 1 uses the cleaning blade 35 having the loss elastic modulus E ″ that satisfies the above-described regulations, so that the charge amount of the toner, which is one of the conditions for obtaining good cleaning properties, can be widened. In addition, various types of toners having different charge amounts can be handled, including generally widely used charge amount toners.

  In this embodiment, the circularity of the toner base particles handled by the image forming apparatus 1 is defined as 0.980 or less, and the fluidity of the toner is defined as 50 to 100 [%]. A filling toner was used. Generally, as the circularity of the toner base particles is higher, the external additive is more easily peeled off. Actually, since the external additive peeled from the toner base particles slips through between the blade nip 41 and the photosensitive drum 30, the circularity of the toner base particles is specified to be 0.980 or less. Makes it difficult for the toner to be peeled off from the toner base particles, the probability of the external additive being scraped off by the cleaning blade 35 together with the toner base particles is increased, and the cleaning performance is improved. On the other hand, the lower the toner fluidity, the more difficult it is to transfer from the photosensitive drum 30 to the paper P and the amount of waste toner increases. Therefore, the toner fluidity is defined as 50 to 100%. If the transfer from the photosensitive drum 30 to the paper P is facilitated, the amount of waste toner is reduced and the cleaning property is improved.

  As described above, in the image forming apparatus 1, the cleaning property can be further improved by using the toner having a circularity of 0.980 or less and a fluidity of 50 to 100%.

[8. Other Embodiments]
[8-1. Other Embodiment 1]
In the above-described embodiment, the loss elastic modulus E ″ is defined by values at two temperatures of 70 ° C. and 100 ° C., but these two temperatures and any temperature between 70 ° C. and 100 ° C. The value may be specified at three temperatures, or the value may be specified at four or more temperatures.In fact, in addition to 70 ° C. and 100 ° C., for example, a value at 85 ° C. , The loss elastic modulus E ″ of the cleaning blades A to G used in the printing test is measured at 85 ° C. For example, the value of the loss elastic modulus E ″ at 85 ° C. of the cleaning blade D for which the OK determination is given as the evaluation of the cleaning property is decreased, and the value of the loss elastic modulus E ″ of the cleaning blade A at 85 ° C. is decreased. What is necessary is just to prescribe | regulate in the range made into an upper limit. Incidentally, the loss elastic modulus E ″ can be defined at a temperature exceeding 100 ° C. However, if the local temperature of the blade nip 41 exceeds 100 ° C., the cleaning blade 35 and the toner are adversely affected. Since possibility arises, it is desirable to prescribe | regulate at the temperature between 70 to 100 degreeC.

[8-2. Other Embodiment 2]
In the above-described embodiment, the present invention is applied to the image forming apparatus 1 that is an electrophotographic printer. However, the present invention is not limited thereto, and the developing devices 3K, 3M, 3Y, and 3C of the image forming apparatus 1 are used. Can be applied to image forming apparatuses such as MFPs (Multi Function Products), facsimile machines, and copiers.

[8-3. Other Embodiment 3]
Further, in the above-described embodiment, the charging roller 33 is used as a specific example of the charging member that charges the photosensitive drum 30 as the image carrier. However, the present invention is not limited thereto, and a charging member having a structure different from that of the charging roller 33 may be used as long as it has a function of charging the image carrier. Further, in the above-described embodiment, the developing roller 31 is used as a specific example of the developing unit that forms a toner image as a developer image on the image carrier. The developing unit having a structure different from that of the developing roller 31 may be used as long as it has a function of forming a developer image on the image carrier. Furthermore, in the above-described embodiment, the transfer roller 14 (14K, 14M, 14C, 14Y) is used as a specific example of the transfer unit that transfers the toner image as the developer image onto the paper P as the medium. Not limited to this, a transfer unit having a structure different from that of the transfer roller 14 may be used as long as it has a function of transferring a developer image to a medium.

[8-4. Other Embodiment 4]
Furthermore, the present invention is not limited to the above-described embodiment and other embodiments. That is, the scope of application of the present invention extends to embodiments in which some or all of the above-described embodiments and other embodiments are arbitrarily combined, and embodiments in which some are extracted.

  The present invention can be widely used in an image forming apparatus that cleans toner by scraping it off with a cleaning member.

  DESCRIPTION OF SYMBOLS 1, Image forming apparatus, 3K, 3M, 3Y, 3C ... Developing device, 6 ... Transfer belt, 14K, 14M, 14Y, 14C ... Transfer roller, 30 ... Photosensitive drum, 31 ... Developing roller, 32 ... Supply roller, 33... Charging roller, 35... Cleaning blade, 40... Blade holder, 41 .. Blade nip, 70.

Claims (6)

An image carrier on which an electrostatic latent image is formed;
A charging member for charging the image carrier;
A developing unit for forming a developer image by attaching a developer added with an external additive to the image carrier charged by the charging member;
A transfer unit that transfers the developer image formed by the developing unit to a medium;
A cleaning member for removing the developer remaining on the image carrier from the image carrier,
The cleaning member is
An image forming apparatus, wherein the elastic member has a loss elastic modulus at a measurement temperature of 100 ° C. in a range of 3.00 × 10 ⁴ [Pa] to 7.70 × 10 ⁴ [Pa]. The cleaning member is
The loss elastic modulus at a measurement temperature of 70 ° C. is an elastic body included in a range of 1.60 × 10 ⁵ [Pa] to 2.01 × 10 ⁵ [Pa]. Image forming apparatus. The developer is composed of mother particles and an external additive,
The image forming apparatus according to claim 1, wherein the circularity of the mother particle is 0.980 or less. The image forming apparatus according to claim 1, wherein the flowability of the developer is 50% to 100%. The image carrier is a cylindrical drum,
The cleaning member is a plate-like blade, and is arranged so that the tip of the blade is pressed against the surface of the drum, and scrapes off the developer remaining on the surface of the drum at the tip of the blade. The image forming apparatus according to claim 1, wherein the image forming apparatus is dropped. The image forming apparatus according to claim 5, wherein a cleaning angle between a front end portion of the cleaning member and a surface of the drum is 10.3 degrees to 14.7 degrees.

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