Charging apparatus, assembly, and image forming apparatus

Abstract

It suppresses the increase in electrical resistance of charged objects. [Solution] The charging device 34 includes a charging roll 40, which is an example of a charging body, that rotates in contact with a photoreceptor 32, which is an example of an object to be charged, to charge the object to be charged, and a cleaning brush 50, which is an example of a cleaning body, that contacts the charged object to clean the charged object and has a contact pressure of 0.01 N / cm or more and 0.05 N / cm or less on the charged object.

Description

Technical Field

[0001] The present disclosure relates to a charging device, an assembly, and an image forming apparatus.

Background Art

[0002] Patent Document 1 discloses an image forming apparatus including an image carrier, a charging member, and a cleaning member. The image carrier rotates by receiving a driving force. The charging member abuts against the image carrier and is driven to rotate therewith to charge the image carrier. The cleaning member abuts against the charging member and is driven to rotate therewith to clean the charging member. The contact pressure at which the cleaning member abuts against the charging member is within the range of 0.05 to 0.6 N / cm.

[0003] Patent Document 2 discloses a cleaning device that cleans by bringing a cleaning member into contact with the surface of a charging roll that rotates while contacting an image carrier to charge the image carrier. In this cleaning device, the cleaning member is a foam, and the density is 26 kg / m 3 or more and 240 kg / m 3 or less, and the hardness is 21 N or more and 441 N or less.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] A possible charging device includes a charging body and a cleaning body. The charging body rotates, for example, in contact with an object to be charged, thereby charging the object. The cleaning body cleans the charging body by contacting it. In this case, if the contact pressure of the cleaning body against the charging body exceeds 0.05 N / cm, residual deposits on the charging body (e.g., toner, external additives, and discharge products) may be pressed against it by the cleaning body. As a result, a layer of these deposits may form on the charging body, increasing its electrical resistance.

[0006] On the other hand, if the contact pressure of the cleaning body with respect to the charged body falls below 0.01 N / cm, the cleaning performance of the cleaning body may decrease, and deposits may remain. As a result, the electrical resistance of the charged body may increase.

[0007] This disclosure aims to suppress the increase in the electrical resistance of a charged object when the contact pressure of the cleaning body with the charged object exceeds 0.05 N / cm, and when the contact pressure is less than 0.01 N / cm. [Means for solving the problem]

[0008] The first embodiment comprises a charging body that rotates in contact with an object to be charged and charges the object to be charged, and a cleaning body that has a brush that contacts the charging body and cleans the charging body, wherein the contact pressure with the charging body is 0.01 N / cm or more and 0.05 N / cm or less.

[0009] In the second embodiment, in the first embodiment, the cleaning body has a contact pressure of 0.02 N / cm or more and 0.04 N / cm or less.

[0010] In the third embodiment, in the first embodiment, the cleaning body has a wire diameter of 20 μm or less at the tip of the brush.

[0011] In the fourth embodiment, as in the third embodiment, the cleaning body has a wire diameter of 15 μm or less at the tip of the brush.

[0012] In the fifth embodiment, as in the third embodiment, the cleaning body has a wire diameter of 5 μm or more at the tip of the brush.

[0013] The sixth aspect is that, in the first aspect, the surface roughness of the charged body is 6.5 μm or less.

[0014] The seventh aspect is the sixth aspect, wherein the surface roughness of the charged body is 5.0 μm or less.

[0015] The eighth aspect is an assembly comprising a charged object, a charging body that rotates in contact with the charged object and charges the charged object, and a cleaning body that has a brush that contacts the charged object and cleans the charged object, wherein the contact pressure with the charged object is 0.01 N / cm or more and 0.05 N / cm or less, and the charged object, the charging body, and the cleaning body are assembled to be integrally and detachably attached to the main body of the device.

[0016] The ninth embodiment is an image forming apparatus comprising: a photoreceptor as the charged body; a charging device according to any one of the first to seventh embodiments, wherein the charged body contacts and rotates the photoreceptor to charge the photoreceptor; an exposure device for exposing the photoreceptor charged by the charged body to form an electrostatic latent image; and a developing device for developing the electrostatic latent image formed on the photoreceptor by the exposure device. [Effects of the Invention]

[0017] According to the configuration of the first embodiment, when the contact pressure of the cleaning body with respect to the charged body exceeds 0.05 N / cm, and when the contact pressure is less than 0.01 N / cm, the increase in the electrical resistance of the charged body is suppressed.

[0018] According to the configuration of the second embodiment, the increase in the electrical resistance of the charged body is suppressed compared to when the contact pressure of the cleaning body with the charged body exceeds 0.04 N / cm and when the contact pressure is below 0.02 N / cm.

[0019] According to the configuration of the third embodiment, the increase in the electrical resistance of the charged body is suppressed compared to the case where the wire diameter of the tip of the brush exceeds 20 μm.

[0020] According to the configuration of the fourth aspect, an increase in the electrical resistance of the charging member is suppressed as compared with the case where the wire diameter at the tip of the brush exceeds 15 μm.

[0021] According to the configuration of the fifth aspect, a decrease in the durability of the brush is suppressed as compared with the case where the wire diameter at the tip of the brush is less than 5 μm.

[0022] According to the configuration of the sixth aspect, an increase in the electrical resistance of the charging member is suppressed as compared with the case where the surface roughness of the charging member exceeds 6.5 μm.

[0023] According to the configuration of the seventh aspect, an increase in the electrical resistance of the charging member is suppressed as compared with the case where the surface roughness of the charging member exceeds 5.0 μm.

[0024] According to the configuration of the eighth aspect, an increase in the electrical resistance of the charging member is suppressed as compared with the case where the contact pressure of the cleaning member against the charging member exceeds 0.05 N / cm and the case where the contact pressure is less than 0.01 N / cm.

[0025] According to the configuration of the ninth aspect, unevenness in image density is suppressed as compared with the case where the contact pressure of the cleaning member against the charging member exceeds 0.05 N / cm and the case where the contact pressure is less than 0.01 N / cm.

Brief Description of Drawings

[0026] [Figure 1] It is a schematic diagram showing the configuration of an image forming apparatus according to the present embodiment. [[ID=3Z]] [Figure 2] It is a schematic diagram showing the configuration of a charging device according to the present embodiment. [Figure 3] It is a table showing evaluation results.

Mode for Carrying Out the Invention

[0027] Hereinafter, an example of an embodiment according to the present invention will be described based on the drawings.

[0028] <Image forming apparatus 10> The image forming apparatus 10 according to this embodiment will now be described. Figure 1 is a schematic diagram showing the image forming apparatus 10 according to this embodiment.

[0029] The image forming apparatus 10 shown in Figure 1 is an image forming apparatus. Specifically, as shown in Figure 1, the image forming apparatus 10 comprises an image forming apparatus body 11, a media storage unit 12, a transport unit 13, and an image forming unit 14. The parts of the image forming apparatus 10 will be described below.

[0030] <Image forming apparatus main body 11> The image forming apparatus body 11 shown in Figure 1 is an example of the apparatus body. This image forming apparatus body 11 is the part where each component of the image forming apparatus 10 is provided. The image forming apparatus body 11 is composed of, for example, a frame (not shown) that forms the skeleton of the image forming apparatus 10.

[0031] <Media storage unit 12 and transport unit 13> The media storage section 12 is the part of the image forming apparatus 10 that houses the recording medium P. The recording medium P housed in this media storage section 12 is supplied to the image forming section 14. The recording medium P housed in the media storage section 12 is the object on which an image is formed by the image forming section 14. Examples of recording medium P include paper and film. Examples of film include resin film and metal film. However, the recording medium P is not limited to those mentioned above, and various recording media can be used.

[0032] The transport unit 13 shown in Figure 1 transports the recording medium P stored in the media storage unit 12 to the discharge unit 18. Specifically, as shown in Figure 1, the transport unit 13 has a plurality of transport members 13A such as transport rolls, and the recording medium P is transported by the transport members 13A. The transport members 13A may be, for example, transport belts and transport drums, and various transport members can be used.

[0033] <Image forming unit 14> The image forming unit 14 shown in Figure 1 forms an image on the recording medium P transported by the transport unit 13 (specifically, the transport member 13A). Specifically, the image forming unit 14 forms a toner image (an example of an image) on the recording medium P using an electrophotographic method. More specifically, as shown in Figure 1, the image forming unit 14 includes toner image forming units 20Y, 20M, 20C, and 20K (hereinafter referred to as 20Y to 20K), a transfer body 24, and a fixing unit 26.

[0034] Each of the toner image forming units 20Y to 20K is a process cartridge and is assembled to be detachably attached to the main body 11 of the image forming apparatus. Each of the toner image forming units 20Y to 20K has a photoreceptor 32. Since the toner image forming units 20Y to 20K are configured similarly, the reference numerals for the parts of the toner image forming units 20Y, 20M, and 20C are omitted in Figure 1.

[0035] The photoreceptor 32 has the function of retaining a latent image. Specifically, the photoreceptor 32 rotates in one direction (for example, counterclockwise in Figure 1). Around the photoreceptor 32, in order from the upstream side in the direction of rotation of the photoreceptor 32, are a charging device 34, an exposure device 36, and a developing device 38.

[0036] In each of the toner image forming sections 20Y to 20K, the charging device 34 charges the photoreceptor 32 (charging step). Furthermore, the exposure device 36 exposes the photoreceptor 32, which has been charged by the charging device 34, to form a latent image (specifically, an electrostatic latent image) on the photoreceptor 32 (exposure step). The photoreceptor 32 holds the latent image formed by the exposure device 36. Then, the developing device 38 develops the latent image held by the photoreceptor 32 (development step). As a result, a toner image is formed on the photoreceptor 32. The specific configuration of the charging device 34 will be described later.

[0037] In the image forming unit 14, each of the toner image forming units 20Y to 20K performs charging, exposure, and development processes to form toner images of yellow (Y), magenta (M), cyan (C), and black (K) on the transfer body 24. Furthermore, the image forming unit 14 transfers the toner images of each color formed on the transfer body 24 to the recording medium P, and fixes the toner images to the recording medium P in the fixing unit 26. In this way, the image forming unit 14 uses an intermediate transfer method in which the image is transferred to the recording medium P via the transfer body 24.

[0038] Furthermore, the image forming unit is not limited to an intermediate transfer method; a direct transfer method that directly transfers the image to the recording medium P may also be used, and various image forming units can be applied.

[0039] The photoreceptor 32 is an example of a charged object. Each of the toner image forming units 20Y to 20K is an example of an assembly. In this embodiment, the assembly only needs to include at least the photoreceptor 32 and the charging device 34.

[0040] <Charging device 34> Figure 2 is a schematic diagram showing a charging device 34 according to this embodiment. As shown in Figure 2, the charging device 34 includes a charging roll 40 and a cleaning brush 50. The charging roll 40 is an example of a charging body. The cleaning brush 50 is an example of a cleaning body. The specific configurations of the charging roll 40 and the cleaning brush 50 will be described below.

[0041] <Electrostatic Roll 40> The charging roll 40 rotates in contact with the photoreceptor 32, thereby charging the photoreceptor 32. The charging roll 40 charges the surface of the photoreceptor 32 by, for example, applying a DC voltage or an AC voltage to a DC voltage. The charging roll 40 has a shaft portion 41 and a charging layer 42 made of a resistive elastic layer.

[0042] The shaft portion 41 is made of a conductive material, and generally iron, copper, brass, stainless steel, aluminum, nickel, etc. are used. Other materials besides metals can also be used, as long as they possess conductivity and appropriate rigidity. For example, resin molded products with dispersed conductive particles or ceramics can be used. In addition to a roll shape, a hollow pipe shape is also possible.

[0043] The charging layer 42 can also be configured by dividing it into a resistance layer and an elastic layer supporting them, starting from the outer periphery (i.e., the radially outer side). Furthermore, to provide durability and stain resistance to the charging roll 40, a protective layer can be provided on the outer periphery (i.e., the radially outer side) of the resistance layer as needed.

[0044] The case in which an elastic layer, a resistance layer, and a protective layer are provided on the shaft portion 41 as the charged layer 42 will be described. The material of the elastic layer is conductive or semiconducting, and is generally a resin material or rubber material in which conductive particles or semiconducting particles are dispersed. As resin materials, synthetic resins such as polyester resin, acrylic resin, melamine resin, epoxy resin, urethane resin, silicone resin, urea resin, and polyamide resin are used, and as rubber materials, ethylene-propylene rubber, polybutadiene, natural rubber, polyisobutylene, chloroprene rubber, silicone rubber, urethane rubber, epichlorohydrin rubber, fluorosilicone rubber, ethylene oxide rubber, or foamed materials made by foaming these materials are used.

[0045] As conductive or semiconducting particles, metals such as carbon black, zinc, aluminum, copper, iron, nickel, chromium, and titanium, metal oxides such as ZnO-Al2O3, SnO2-Sb2O3, In2O3-SnO2, ZnO-TiO2, MgO-Al2O3, FeO-TiO2, TiO2, SnO2, Sb2O3, In2O3, ZnO, and MgO, and ionic compounds such as quaternary ammonium salts can be used, and these materials may be used individually or in combination of two or more. Furthermore, if necessary, one or more inorganic fillers such as talc, alumina, and silica, or organic fillers such as fluororesin or silicone rubber fine powder may be mixed in.

[0046] The materials used for the resistive and protective layers are binder resins in which conductive or semiconductive particles are dispersed to control their electrical resistance. Examples of binder resins include acrylic resin, cellulose resin, polyamide resin, methoxymethylated nylon, ethoxymethylated nylon, polyurethane resin, polycarbonate resin, polyester resin, polyethylene resin, polyvinyl resin, polyarylate resin, polythiophene resin, polyolefin resins such as PFA, FEP, and PET, styrene-butadiene resin, melamine resin, epoxy resin, urethane resin, silicone resin, and urea resin.

[0047] The conductive or semiconductive particles are a mixture of one or more types, similar to those in the elastic layer, such as carbon black, metals, metal oxides, and ionic compounds such as quaternary ammonium salts that exhibit ionic conductivity. Additionally, one or more types of additives may be added as needed, including antioxidants such as hindered phenols and hindered amines, inorganic fillers such as clay, kaolin, talc, silica, and alumina, organic fillers such as fine powders of fluororesin or silicone resin, and lubricants such as silicone oil. Furthermore, surfactants and charge control agents may be added as needed.

[0048] Furthermore, methods such as blade coating, Meyer bar coating, spray coating, dipping coating, bead coating, air knife coating, and curtain coating can be used to form these layers.

[0049] The surface roughness Rz of the electrostatic roll 40 is preferably 6.5 μm or less, and more preferably 5.0 μm or less. The lower limit of the surface roughness Rz is not limited, but from the viewpoint of poor image quality (white spots, etc.), it is preferably 2.5 μm or more.

[0050] The surface roughness Rz is measured on the surface of the electrostatic roll 40 using a Surfcom 1400A surface roughness meter (manufactured by Tokyo Seimitsu Co., Ltd.). The measurement is performed in accordance with JIS B0601-1994, with an evaluation length Ln of 4 mm, a reference length L of 0.8 mm, and a cutoff value of 0.8 mm.

[0051] By setting the surface roughness Rz to 6.5 μm or less, the occurrence of axial color streaks and fogging are suppressed when an image is formed. Furthermore, by setting the surface roughness Rz to 6.5 μm or less, it becomes possible to charge the photoreceptor 32 in a more uniform state. Moreover, this effect is effectively exhibited when the surface roughness Rz is 5.0 μm or less.

[0052] <Cleaning brush 50> The cleaning brush 50 has a shaft portion 51 and a brush 52. The shaft portion 51 is rotatably supported on the image forming apparatus body 11.

[0053] The shaft portion 51 is made of a material that has sufficient rigidity to support the brush 52 and maintain the contact pressure to the electrostatic roll 40 as described later. For example, the shaft portion 51 can be made of metals such as iron, copper, brass, stainless steel, aluminum, nickel, etc., as well as resin molded products, ceramics, etc., or materials in which conductive particles are dispersed or inorganic fillers are dispersed. In addition to the roll shape, the shaft portion 51 can also be made of a hollow pipe shape.

[0054] The brush 52 is provided on the outer circumference of the shaft portion 51. Specifically, the brush 52 is arranged around the entire circumference of the shaft portion 51. The brush 52 is composed of fibers that extend radially outward from the shaft portion 51. As a result, the cleaning brush 50 is formed in a circular shape (i.e., a roll shape) as a whole.

[0055] For example, resin fibers such as nylon, acrylic, polypropylene, polyester, and polyethylene terephthalate can be used as the material for the fibers of the brush 52.

[0056] The brush 52 contacts the charged roll 40 to clean it. In this embodiment, the cleaning brush 50 rotates in response to the contact of the brush 52 with the rotating charged roll 40.

[0057] The cleaning brush 50 has a contact pressure of 0.01 N / cm or more and 0.05 N / cm or less with respect to the electrostatic roll 40. Preferably, this contact pressure is less than 0.05 N / cm, and more preferably 0.02 N / cm or more and 0.04 N / cm or less.

[0058] The wire diameter at the tip of the brush 52 (i.e., the part that contacts the charging roll 40) is 20 μm or less. Preferably, this wire diameter is 15 μm or less. Preferably, the wire diameter at the tip of the brush 52 is 5 μm or more.

[0059] The length of the brush 52 is, for example, 1.0 mm or more, preferably 1.5 mm or more. The density of the brush 52 is 60 × 10 3 Books / inch 2 The above 100 x 10 3 Books / inch 2 The following is preferable. Up to this point, we have described cleaning brushes in the form of a roll, but a brush pad, which is constructed by holding a large number of brush fibers with a retaining member to form a pad shape, may also be used.

[0060] <Operation according to this embodiment> The cleaning brush 50 is specified to have a contact pressure of 0.01 N / cm or more and 0.05 N / cm or less on the electrostatic roll 40.

[0061] In this case, if the contact pressure of the cleaning brush 50 against the charging roll 40 exceeds 0.05 N / cm, residual deposits on the charging roll 40 (e.g., toner, external additives, and discharge products) may be pressed against the cleaning brush 50. As a result, a layer of these deposits may form on the charging roll 40, potentially increasing the electrical resistance of the charging roll 40.

[0062] On the other hand, if the contact pressure of the cleaning brush 50 against the charged roll 40 is less than 0.01 N / cm, the cleaning performance of the cleaning brush 50 will decrease, and residue may remain. As a result, the electrical resistance of the charged roll 40 may increase.

[0063] Therefore, according to this embodiment, the increase in the electrical resistance of the charged body is suppressed compared to when the contact pressure of the cleaning brush 50 against the charged roll 40 exceeds 0.05 N / cm and when the contact pressure is below 0.01 N / cm.

[0064] Furthermore, by setting the contact pressure of the cleaning brush 50 on the charged roll 40 to 0.02 N / cm or more and 0.04 N / cm or less, the increase in the electrical resistance of the charged roll 40 is suppressed compared to when the contact pressure exceeds 0.04 N / cm and when the contact pressure falls below 0.02 N / cm.

[0065] In this embodiment, the wire diameter at the tip of the brush 52 is 20 μm or less. Therefore, compared to the case where the wire diameter at the tip of the brush 52 exceeds 20 μm, deposits adhering to the irregularities on the surface of the charging roll 40 are effectively removed, and the increase in the electrical resistance of the charging roll 40 is suppressed.

[0066] Furthermore, by setting the wire diameter at the tip of the brush 52 to 15 μm or less, the increase in the electrical resistance of the charging roll 40 is suppressed compared to the case where the wire diameter at the tip of the brush 52 exceeds 15 μm.

[0067] Furthermore, by making the wire diameter at the tip of the brush 52 5 μm or more, the decrease in the durability of the brush 52 is suppressed compared to when the wire diameter at the tip of the brush 52 is less than 5 μm.

[0068] In this embodiment, the surface roughness Rz of the charging roll 40 is set to 6.5 μm or less. Therefore, the increase in the electrical resistance of the charged body is suppressed compared to the case where the surface roughness of the charging roll 40 exceeds 6.5 μm.

[0069] Furthermore, by setting the surface roughness Rz of the charging roll 40 to 5.0 μm or less, the increase in the electrical resistance of the charged body is suppressed compared to when the surface roughness of the charged body exceeds 5.0 μm.

[0070] <Rating> In the following, we evaluated the density unevenness of the output image and the increase in the electrical resistance of the charging roll for Examples 1 to 7 and Comparative Examples 1 to 3. However, this disclosure is not limited to these examples. <Actual device> A Fujifilm Business Innovation DocuCentreVI C7771 was used as the actual machine. Evaluations were conducted by changing the configuration of the cleaning unit that cleans the electrostatic roll on this machine. <Concentration unevenness grade> After printing 250,000 pages using the actual machine, the density unevenness of the output images was evaluated on a two-level scale: "A" and "B". "A" indicated a level acceptable for commercial use, while "B" indicated a level unacceptable for commercial use. <Increase in the electrical resistance of the charged roll> In this evaluation, the increase in the electrical resistance of the charged roll was determined as follows. First, a sheet-like sample is taken from the charged layer of the charged roll, which is the object to be measured. Using a measuring jig (R12702A / B Resistivity Chamber: Advantest Corporation) and a high-resistance meter (R8340A Digital High-Resistance / Micro-Ammeter: Advantest Corporation), a voltage adjusted to create an electric field (applied voltage / sample thickness) of 1000 V / cm is applied to this sample for 30 seconds, in accordance with JIS K 6911 (1995). The volume resistance is then calculated from the current flowing through the sample. The volume resistance values ​​before printing 250,000 sheets using the actual machine and the volume resistance values ​​after printing 250,000 sheets using the same machine were expressed in common logarithms, and the difference was calculated as the increase in electrical resistance.

[0071] [Example 1] A cleaning brush, specifically a nylon brush (brush 52), was used as the cleaning body. The wire diameter at the tip of the brush was 20 μm. The contact pressure of the cleaning brush against the electrostatic roll was set to 0.01 N / cm. The cleaning brush did not rotate in a driven manner relative to the electrostatic roll. [Example 2] A cleaning brush, specifically a nylon brush (brush 52), was used as the cleaning body. The wire diameter at the tip of the brush was 20 μm. The contact pressure of the cleaning brush against the electrostatic roll was set to 0.05 N / cm. The cleaning brush rotated in a driven manner relative to the electrostatic roll. [Example 3] A cleaning brush, specifically a nylon brush (brush 52), was used as the cleaning body. The wire diameter at the tip of the brush was 20 μm. The contact pressure of the cleaning brush against the electrostatic roll was set to 0.02 N / cm. The cleaning brush did not rotate in a driven manner relative to the electrostatic roll. [Example 4] A cleaning brush, specifically a nylon brush (brush 52), was used as the cleaning body. The wire diameter at the tip of the brush was 20 μm. The contact pressure of the cleaning brush against the electrostatic roll was set to 0.04 N / cm. The cleaning brush rotated in a driven manner relative to the electrostatic roll. [Example 5] A cleaning brush, specifically a nylon brush (brush 52), was used as the cleaning body. The wire diameter at the tip of the brush was 20 μm. The contact pressure of the cleaning brush against the electrostatic roll was set to 0.03 N / cm. The cleaning brush did not rotate in a driven manner relative to the electrostatic roll. [Example 6] A cleaning brush, specifically a nylon brush (brush 52), was used as the cleaning body. The wire diameter at the tip of the brush was 15 μm. The contact pressure of the cleaning brush against the electrostatic roll was set to 0.03 N / cm. The cleaning brush did not rotate in a driven manner relative to the electrostatic roll. [Example 7] A cleaning brush, specifically a nylon brush (brush 52), was used as the cleaning body. The wire diameter at the tip of the brush was 30 μm. The contact pressure of the cleaning brush against the electrostatic roll was set to 0.03 N / cm. The cleaning brush rotated in a driven manner relative to the electrostatic roll. [Comparative Example 1] A cleaning brush, specifically a nylon brush (brush 52), was used as the cleaning body. The wire diameter at the tip of the brush was 20 μm. The contact pressure of the cleaning brush against the electrostatic roll was set to 0.06 N / cm. The cleaning brush rotated in a driven manner relative to the electrostatic roll. [Comparative Example 2] A cleaning brush, specifically a nylon brush (brush 52), was used as the cleaning body. The wire diameter at the tip of the brush was 20 μm. The contact pressure of the cleaning brush against the electrostatic roll was set to 0.005 N / cm. The cleaning brush did not rotate in a driven manner relative to the electrostatic roll. [Comparative Example 3] Instead of a brush, a cleaning roll made of urethane sponge was used as the cleaning body. The contact pressure of the cleaning brush against the electrostatic roll was set to 0.03 N / cm. The cleaning roll rotated in a manner driven by the electrostatic roll. <Evaluation Results> As shown in the results table in Figure 3, the concentration unevenness in Examples 1-7 was rated "A". In contrast, the concentration unevenness in Comparative Examples 1-3 was rated "B". Furthermore, in Examples 1 to 7, the increase in the electrical resistance of the charged roll was less than 3.0 [logΩ]. In contrast, in Comparative Examples 1 to 3, the increase in the electrical resistance of the charged roll was 3.0 [logΩ] or more. As described above, it was confirmed that the increase in the electrical resistance of the charged roll was suppressed in Examples 1 to 7 compared to Comparative Examples 1 to 3. Furthermore, it was confirmed that the increase in the electrical resistance of the charged roll was suppressed more effectively in the range of 0.02 N / cm to 0.04 N / cm (see Examples 3-5) than in the range of 0.01 N / cm to 0.05 N / cm (see Examples 1 and 2) when the contact pressure of the cleaning brush against the charged roll was 0.01 N / cm to 0.05 N / cm. Furthermore, it was confirmed that the increase in the electrical resistance of the charging roll was suppressed more effectively when the wire diameter at the tip of the brush was 15 μm (see Example 6) than when it was 20 μm (see Example 5).

[0072] <Variation> In this embodiment, a photoreceptor 32 was used as an example of an object to be charged, but it is not limited to this. The object to be charged may be, for example, a transporter that transports paper (e.g., a transport roll and a transport belt), or paper itself. The object to be charged includes anything that can be charged by a charged object.

[0073] In this embodiment, a charging roll 40 was used as an example of a charged body, but it is not limited to this. The charged body may be, for example, a belt-shaped charged belt. The charged body includes any material capable of charging an object to be charged.

[0074] In this embodiment, a cleaning brush 50 that rotates in a manner driven by the charged roll 40 is used as an example of a cleaning body, but it is not limited to this. The cleaning body may be, for example, a cleaning brush that contacts the charged roll 40 while stationary. In this case, the cleaning brush 50 does not need to be circular in shape; for example, it can be configured such that a brush 52 is provided on a plate-shaped support member facing the charged roll 40. The cleaning body may include one having a brush that contacts and cleans a charged object.

[0075] The present invention is not limited to the embodiments described above, and various modifications, changes, and improvements are possible without departing from the spirit of the invention. For example, the modified forms shown above may be combined in any way.

[0076] (Note) (((1))) A charged body that rotates in contact with an object to be charged, thereby charging the object to be charged, A cleaning body having a brush that contacts the charged object and cleans the charged object, wherein the contact pressure with respect to the charged object is 0.01 N / cm or more and 0.05 N / cm or less, A charging device equipped with the following features. (((2))) The cleaning body is The aforementioned contact pressure is 0.02 N / cm or more and 0.04 N / cm or less. The charging device described in (((1))). (((3))) The cleaning body is The wire diameter at the tip of the brush is 20 μm or less. A charging device as described in (((1))) or (((2))). (((4))) The cleaning body is The wire diameter at the tip of the brush is 15 μm or less. The charging device described in (((3))). (((5))) The cleaning body is The wire diameter at the tip of the brush is 5 μm or more. A charging device as described in (((3))) or (((4))). (((6))) The surface roughness of the charged body is 6.5 μm or less. A charging device as described in any one of (((1))) to (((5))). (((7))) The surface roughness of the charged body is 5.0 μm or less. The charging device described in (((6))). (((8))) The charged object and, A charged body that rotates in contact with an object to be charged, thereby charging the object to be charged, A cleaning body having a brush that contacts the charged object and cleans the charged object, wherein the contact pressure with respect to the charged object is 0.01 N / cm or more and 0.05 N / cm or less, Equipped with, An assembly in which the charged object, the charged object, and the cleaning object are assembled to be detachably attached to the main body of the device. (((9))) The photoreceptor as the charged object, A charging device according to any one of (((1))) to (((7))), wherein the charged body contacts and rotates the photoreceptor to charge the photoreceptor, An exposure apparatus that exposes the photoreceptor charged by the aforementioned charged body to form an electrostatic latent image, A developing apparatus for developing the electrostatic latent image formed on the photoreceptor by the exposure apparatus, An image forming apparatus equipped with the following features.

[0077] According to the configuration of (((1))), when the contact pressure of the cleaning body on the charged body exceeds 0.05 N / cm, and when the contact pressure is less than 0.01 N / cm, the increase in the electrical resistance of the charged body is suppressed. According to the configuration of (((2))), when the contact pressure of the cleaning body with respect to the charged body exceeds 0.04 N / cm, and when the contact pressure is less than 0.02 N / cm, the increase in the electrical resistance of the charged body is suppressed. According to the configuration of (((3))), the increase in the electrical resistance of the charged body is suppressed compared to the case where the wire diameter of the brush tip exceeds 20 μm. According to the configuration of (((4))), the increase in the electrical resistance of the charged body is suppressed compared to the case where the wire diameter of the brush tip exceeds 15 μm. According to the configuration of (((5))), the decrease in brush durability is suppressed compared to the case where the wire diameter of the brush tip is less than 5 μm. According to the configuration of (((6))), the increase in the electrical resistance of the charged body is suppressed compared to the case where the surface roughness of the charged body exceeds 6.5 μm. According to the configuration of (((7))), the increase in the electrical resistance of the charged body is suppressed compared to the case where the surface roughness of the charged body exceeds 5.0 μm. According to the configuration of (((8))), when the contact pressure of the cleaning body with respect to the charged body exceeds 0.05 N / cm, and when the contact pressure is less than 0.01 N / cm, the increase in the electrical resistance of the charged body is suppressed. According to the configuration of (((9))), when the contact pressure of the cleaning body against the charged body exceeds 0.05 N / cm, and when the contact pressure is less than 0.01 N / cm, the density unevenness of the image is suppressed. [Explanation of symbols]

[0078] 10 Image forming apparatus 20Y~20K Toner Image Forming Unit (Example of Assembly) 32. Photoreceptor (an example of an electrostatically charged material) 34 Charging device 36 Exposure apparatus 38. Developing device 40. Charged Roll (An example of a charged object) 50 Cleaning brush (an example of a cleaning tool)

Claims

1. A charged body that rotates in contact with an object to be charged, thereby charging the object to be charged, A cleaning body having a brush that contacts the charged object and cleans the charged object, wherein the contact pressure with respect to the charged object is 0.01 N / cm or more and 0.05 N / cm or less, A charging device equipped with the following features.

2. The cleaning body is The aforementioned contact pressure is 0.02 N / cm or more and 0.04 N / cm or less. The charging device according to claim 1.

3. The cleaning body is The wire diameter at the tip of the brush is 20 μm or less. The charging device according to claim 1.

4. The cleaning body is The wire diameter at the tip of the brush is 15 μm or less. The charging device according to claim 3.

5. The cleaning body is The wire diameter at the tip of the brush is 5 μm or more. The charging device according to claim 3.

6. The surface roughness of the charged body is 6.5 μm or less. The charging device according to claim 1.

7. The surface roughness of the charged body is 5.0 μm or less. The charging device according to claim 6.

8. The charged object and, A charged body that rotates in contact with an object to be charged, thereby charging the object to be charged, A cleaning body having a brush that contacts the charged object and cleans the charged object, wherein the contact pressure with respect to the charged object is 0.01 N / cm or more and 0.05 N / cm or less, Equipped with, An assembly in which the charged object, the charged object, and the cleaning object are assembled to be detachably attached to the main body of the device.

9. The photoreceptor as the charged object, A charging device according to any one of claims 1 to 7, wherein the charged body contacts and rotates the photoreceptor to charge the photoreceptor, An exposure apparatus that exposes the photoreceptor charged by the aforementioned charged body to form an electrostatic latent image, A developing apparatus for developing the electrostatic latent image formed on the photoreceptor by the exposure apparatus, An image forming apparatus equipped with the following features.

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