Cleaning device, process cartridge, and image forming apparatus

Abstract

To provide a cleaning device that can uniformly and efficiently remove dirt attached to a rotating body, and can prevent the occurrence of abnormal images including mainly vertical black streaks over a long period.SOLUTION: A cleaning device has cleaning means 22b that is in contact with a surface of a rotating body 22a to clean the surface of the rotating body 22a. The cleaning means 22b is a roller member and has a foam layer 224 in contact with the surface of the rotating body 22a, and the surface of the foam layer 224 has a coefficient of static friction of 0.5 or more, which is measured by the Euler belt method.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to a cleaning device, a process cartridge, and an image forming apparatus.

Background Art

[0002] In an electrophotographic image forming apparatus, the surface of a photoreceptor, which is an image carrier, is charged, the charged photoreceptor surface is exposed to form an electrostatic latent image, toner is supplied to the electrostatic latent image, and a toner image is formed. The toner image formed on the photoreceptor is transferred onto a recording paper or the like and fixed onto the recording paper or the like under heat and pressure. Since there is toner remaining on the photoreceptor surface without being transferred after the toner image transfer, the photoreceptor surface is cleaned by a cleaning blade or the like before entering the next charging step. However, there is a problem that the transfer residual toner remaining on the photoreceptor surface after the toner image transfer is not completely removed in the cleaning step, and when it reaches a region close to or in contact with the charging roller, these transfer residual toners adhere to the charging roller, the transfer belt, or the like.

[0003] In recent years, the demand for high image quality and high definition has increased, and in the developing process, toners with smaller particle sizes and spherical shapes have been increasingly used. By using such toners, it is intended to densely attach the toner to the electrostatic latent image. However, such toners with smaller particle sizes and spherical shapes are likely to pass through the cleaning blade in the cleaning step, and cleaning failure is likely to occur.

[0004] On the other hand, attempts have been made to improve the cleaning performance by applying a lubricant such as zinc stearate to the surface of the image carrier to reduce the friction coefficient of the surface and reduce the frictional force acting between the surface of the image carrier and the member in contact therewith. However, if there is powder of the lubricant that has not been fully formed into a film, there is a problem that they pass through the cleaning blade and adhere to the charging roller or the like in the same manner as the toner.

[0005] When toner or lubricant adheres to the charging roller, the resistance on the surface of the charging roller locally increases, resulting in a decrease in the charging ability of the charging roller in a part of the axial direction and making it impossible to uniformly charge the image carrier. As a result, there is a problem that vertical black streaks (abnormal images) of the image are likely to appear, especially in a low-temperature and low-humidity environment.

[0006] In contrast, as a cleaning means for the charging roller, a cleaning roller provided with a resin foam has been proposed (see, for example, Patent Documents 1 and 2). In Patent Document 1, a cleaning roller made of a resin foam (for example, a melamine resin foam) having an open-cell structure with a density of 5 to 15 kg / m 3 and a tensile strength of 1.7 ± 0.5 kg / cm 2 is disclosed. In Patent Document 2, a cleaning roller having a spiral cleaning member made of a urethane foam sponge and a roller is disclosed, and cleaning is performed by a speed difference between the peripheral speed of the roller and the peripheral speed of the outer periphery of the spiral cleaning member.

Summary of the Invention

Problems to be Solved by the Invention

[0007] In a cleaning member using a foam on the outer periphery, the same part in the axial direction may continuously contact the rotating body to be cleaned, resulting in a state where dirt is likely to accumulate only in that part.

[0008] The fundamental cause of the generation of abnormal images due to the adhesion of foreign substances to rotating bodies such as charging rollers and transfer belts is that resistance unevenness occurs due to a large local difference in the adhesion amount of foreign substances. To suppress this, it is important to efficiently remove foreign substances on the rotating body to prevent the accumulation of foreign substances and at the same time remove foreign substances uniformly.

[0009] Therefore, an object of the present invention is to provide a cleaning device that can uniformly and efficiently remove dirt adhering to a rotating body and suppress the generation of abnormal images mainly composed of vertical black streaks over a long period of time.

Means for Solving the Problem

[0010] In order to solve the above problems, a cleaning device of the present invention is a cleaning device having cleaning means that abuts on the surface of a rotating body and cleans the surface of the rotating body, wherein the cleaning means is a roller member, and is provided with a foam layer that abuts on the surface of the rotating body, and the static friction coefficient measured by the Euler belt method on the surface of the foam layer is 0.5 or more.

Effect of the Invention

[0011] According to the present invention, it is possible to provide a cleaning device that can uniformly and efficiently remove dirt adhering to a rotating body and suppress the occurrence of abnormal images mainly composed of vertical black streaks over a long period of time.

Brief Description of the Drawings

[0012]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Mode for Carrying Out the Invention

[0013] Hereinafter, a cleaning device, a process cartridge, and an image forming apparatus according to the present invention will be described with reference to the drawings. Note that the present invention is not limited to the embodiments shown below, and can be changed within the scope that those skilled in the art can conceive, such as other embodiments, additions, modifications, deletions, etc., and is included in the scope of the present invention as long as the functions and effects of the present invention are exhibited in any aspect.

[0014] FIG. 1 is a schematic configuration diagram showing an example of an image forming apparatus according to the present invention. FIGS. 2 and 3 are schematic configuration diagrams showing an example of a process cartridge according to the present invention.

[0015] The image forming apparatus of the present embodiment includes at least a latent image carrier that carries a latent image, a charging means that charges the surface of the latent image carrier by a charging member composed of a rotating body, and a cleaning device that has a cleaning means that contacts the surface of the charging member and cleans the surface of the charging member. The cleaning means is a roller member, the roller member includes a foam layer that contacts the surface of the rotating body, and the static friction coefficient measured by the Euler belt method on the surface of the foam layer is 0.5 or more.

[0016] Further, the process cartridge of the present embodiment includes at least an image carrier that forms a latent image, a charging unit that charges the surface of the image carrier by a charging member formed of a rotating body, and a cleaning device that has a cleaning unit that contacts the surface of the charging member and cleans the surface of the charging member. The process cartridge is detachable from the main body of the image forming apparatus. The cleaning unit is a roller member, and the roller member includes a foam layer that contacts the surface of the rotating body. The static friction coefficient measured by the Euler belt method on the surface of the foam layer is 0.5 or more.

[0017] The image forming apparatus 1 shown in FIG. 1 is a four-unit tandem type image forming apparatus. This image forming apparatus 1 includes an image forming device 10, an optical writing device 11, a paper feeding device 12, a secondary transfer device 13, a fixing device 14, a paper discharging device 15, and a paper discharge tray 16. The image forming device 10 includes process cartridges 10Y, 10M, 10C, and 10K which are image forming units for each color of Y (yellow), M (magenta), C (cyan), and K (black). The photoreceptors 21 which are latent image carriers of the respective process cartridges 10Y, 10M, 10C, and 10K contact the intermediate transfer belt 17, and the toner image formed on the photoreceptor 21 is primarily transferred by the primary transfer device 18. Hereinafter, when representing colors, they are represented as Y, M, C, and K.

[0018] FIG. 2 is a schematic configuration diagram showing an example of a K-color process cartridge. Inside the process cartridge 10K, a drum-shaped photoreceptor 21, a charging device 22, a developing device 23, a photoreceptor cleaning device 24, and a charge eliminating device (not shown) arranged along the outer periphery of the photoreceptor 21 are provided. Between the charging device 22 and the developing device 23, an optical writing unit 26 for irradiating laser light for optical writing from the optical writing device 11 is set. The charge eliminating device is provided at 25 between the photoreceptor cleaning device 24 and the charging device 22.

[0019] The charging device 22 includes a charging roller 22a disposed with a gap (gap) from the photosensitive drum 21, and a cleaning device according to the present invention for removing dirt from the charging roller 22a. The cleaning device includes cleaning means 22b which is a roller member. The developing device 23 includes a developing roller 23a and stirring rollers 23b, 23c.

[0020] In this image forming apparatus 1, laser light modulated based on image data to be imaged is written from the optical writing device 11 onto the photosensitive member 21 which is a latent image carrier whose surface is charged to a predetermined potential by the charging device 22, and a latent image is formed on the photosensitive member 21. The latent image is developed by the developing device 23 as the photosensitive member 21 rotates, and a toner image is formed. This toner image is primarily transferred onto the intermediate transfer belt 17 by the primary transfer device 18. This primary transfer is also executed by the color image forming units 10Y, 10M, 10C which are colors other than black, and finally a full-color image in which four-color toner images are superimposed is formed on the intermediate transfer belt 17.

[0021] The toner image formed on the intermediate transfer belt 17 is batch-transferred onto the paper fed from any one of the paper feed trays 12a of the paper feeding device 12 by the secondary transfer device 13. At this time, the paper is fed onto the vertical conveyance path 12c in synchronization with the image on the intermediate transfer belt 17 by the registration roller 12b. The full-color image transferred onto the paper is fixed onto the paper by heating and pressurization by the fixing device 14, and is discharged onto the discharge tray 16 from the discharge device 15.

[0022] The photoreceptor 21 onto which the toner image has been primarily transferred has the residual toner T on the surface of the photoreceptor 21 cleaned by the photoreceptor cleaning device 24, and further, the surface of the photoreceptor 21 is discharged by a discharging device. The photoreceptor cleaning device 24 includes a cleaning blade 24a and a waste toner conveying member 24b. The cleaning blade 24a scrapes off the residual toner T, and the scraped residual toner T is conveyed and collected by the waste toner conveying member 24b. The intermediate transfer belt 17 is stretched between a driving roller and a driven roller, and a cleaning device 17a for the intermediate transfer belt 17 is provided on the driving roller side.

[0023] Note that the configurations of the process cartridges 10Y, 10M, and 10C for Y, M, and C colors are the same as those of the process cartridge 10K for K color.

[0024] FIG. 3 is a schematic configuration diagram showing another example of the process cartridge for K color. In the process cartridge shown in FIG. 3, a lubricant application device 27 is provided to improve the cleaning performance and transferability of the photoreceptor 21. The lubricant application device 27 is provided on the downstream side of the photoreceptor cleaning device 24 with respect to the rotation direction R of the photoreceptor 21 for stabilizing the lubricant application. The lubricant application is stabilized because by arranging the lubricant application device 27 on the downstream side of the photoreceptor cleaning device 24, it becomes possible to apply the lubricant to the surface of the photoreceptor 21 after removing the transferred residual toner T.

[0025] The lubricant application device 27 includes a lubricant 27a, a brush roller 27b, a compression spring 27c, and an application blade 27d. The lubricant application device 27 is arranged on the downstream side of the photoreceptor cleaning device 24 with respect to the rotation direction of the photoreceptor 21. The lubricant 27a is solid. The brush roller 27b rotates in contact with the lubricant 27a and the photoreceptor 21, and scrapes the lubricant 27a to apply it to the photoreceptor 21. The lubricant 27a is pressed toward the brush roller 27b by the compression spring 27c, and the contact state with the brush roller 27b is maintained.

[0026] FIG. 4 is a perspective view showing an example of the arrangement relationship between the charging device 22 and the photoreceptor 21. The charging device 22 includes a charging roller 22a as a charging member disposed opposite to a photoreceptor (hereinafter also referred to as a "photoreceptor drum") 21, and a cleaning means 22b disposed so as to contact a surface of the charging roller 22a opposite to the surface facing the photoreceptor drum 21. Further, the charging roller 22a includes a pressure spring 19 which is a biasing member that biases both ends thereof toward the photoreceptor drum 21 side, respectively.

[0027] The rotating body to be cleaned by the cleaning means 22b according to the present invention is, for example, a charging member (charging roller 22a). The charging roller 22a includes a conductive member and a conductive support member that rotatably supports the conductive member. As the conductive member, a known material can be used, but a material that is less likely to have foreign matter adhere to its surface and can efficiently remove the adhered foreign matter is preferable. For example, it is preferably a hard resin member. By combining the charging roller 22a provided with a conductive member made of a hard resin member with the cleaning device according to the present invention, a great effect of removing foreign matter and suppressing the occurrence of abnormal images can be obtained.

[0028] FIG. 5(A) is a schematic cross-sectional view of the charging roller 22a. The charging roller 22a includes a mandrel 221 as a columnar conductive support member, and a resistance adjustment layer 222 as a conductive member formed with a uniform thickness on the outer peripheral surface of the mandrel 221. The resistance adjustment layer 222 is formed by providing a resin composition on the peripheral surface of the mandrel 221 by extrusion molding, injection molding, or the like. The resistance adjustment layer 222, which is a conductive member, has a JIS-D hardness of 45 degrees or more in order to prevent deformation over time and change in the gap between the photoreceptor drum 21 and the charging roller 22a.

[0029] Examples of the material used for the resistance adjustment layer 222 include thermoplastic resins, and there is no particular limitation as long as it can maintain a JIS-D hardness of 45 degrees or more after molding. However, a material that is easy to mold is preferred. For example, general-purpose resins such as polyethylene (PE), polypropylene (PP), polymethyl methacrylate (PMMA), polystyrene (PS), and its copolymers (AS, ABS, etc.) can be mentioned.

[0030] The resistance adjustment layer 222 is formed of a thermoplastic resin composition in which a polymer type ion conductive agent is dispersed. The volume resistivity of this resistance adjustment layer 222 is 10 6 ~10 9 Ω·cm is desirable. If the volume resistivity exceeds 10 9 Ω·cm, the amount of charge is insufficient, and it becomes impossible to obtain a sufficient charging potential for the photoreceptor 21 to obtain a uniform image. On the other hand, if the volume resistivity is less than 10 6 Ω·cm, leakage occurs throughout the photoreceptor 21.

[0031] Examples of the polymer type ion conductive agent dispersed in the thermoplastic resin preferably have a single resistance value of about 10 6 ~10 10 Ω·cm and are easy to lower the resistance of the resin. For example, compounds containing a polyether ester amide component can be mentioned. In this case, in order to set the resistance value of the resistance adjustment layer 222 to a desired value, the blending amount of the polymer type ion conductive agent is preferably in the range of 30 to 70 parts by weight with respect to 100 parts by weight of the base material. On the other hand, as the polymer type ion conductive agent, a quaternary ammonium base-containing polymer compound can also be used. Examples of the resistance adjustment layer include quaternary ammonium base-containing polyolefins. In this case, in order to set the resistance value of the resistance adjustment layer 222 to a desired value, the blending amount of the polymer type ion conductive agent is preferably in the range of 10 to 40 parts by weight with respect to 100 parts by weight of the base material.

[0032] The dispersion of the polymer-type ionic conductive agent in the thermoplastic resin can be easily carried out by using means such as a twin-screw kneader or a kneader. Since the ionic conductive material is uniformly dispersed at the molecular level in the matrix polymer, there is no variation in the resistance value due to poor dispersion of the conductive substance as seen in the resistance adjustment layer in which the conductive pigment is dispersed in the resistance adjustment layer 222. Further, since the ionic conductive material is a high molecular compound, it is uniformly dispersed and fixed in the matrix polymer, and bleeding out is less likely to occur.

[0033] The charging roller 22a is connected to a power source (not shown) and a predetermined voltage is applied. The applied voltage may be only a direct current (DC) voltage, but it is preferably a voltage obtained by superimposing an alternating current (AC) voltage on the DC voltage. By applying the AC voltage, the surface of the photoreceptor 21 can be charged more uniformly. Also, the charging roller 22a may be provided in contact with the photoreceptor 21, but in the embodiment of the present invention, it is preferably disposed with a minute gap with respect to the photoreceptor drum 21. Although not shown, this minute gap can be set by winding a spacer member having a certain thickness around the non-image forming regions at both ends of the charging roller 22a so that the surface of the spacer member abuts against the surface of the photoreceptor drum 21.

[0034] FIG. 5(B) is a schematic cross-sectional view of the cleaning means 22b. The cleaning means 22b is a roller member and includes at least a foam layer 224 that abuts against the surface of the rotating body to be cleaned and a core material (shaft) 223 that rotatably supports the foam layer 224. As the cleaning device, in addition to the cleaning means 22b, other members may be provided as necessary.

[0035] The material of the core material 223 is not particularly limited and can be appropriately selected according to the purpose, and examples thereof include resins and metals. Examples of the resin include epoxy resins and phenolic resins. Examples of the metal include iron, aluminum, and stainless steel.

[0036] The foam layer 224 is formed on the outer periphery of the core material 223. In the cleaning device of the present invention, the static friction coefficient of the surface of the foam layer 224 is 0.5 or more by the Euler belt method.

[0037] The measurement method of the static friction coefficient of the surface of the foam layer 224 by the Euler belt method will be described based on FIG. 6. FIG. 6 is a schematic configuration diagram of an Euler belt type measuring device. The measuring device includes a substrate 51, a linear motor 52, a digital push-pull gauge 53, a weight 54, an object to be measured 55 (cleaning means 22b), a paper belt 56, and a thread 57. Fix the object to be measured 55 so that it cannot rotate in the vicinity of the substrate 51 arranged horizontally, and place the belt 56 thereon. The belt 56 is in contact with a quarter of the outer periphery of the object to be measured 55. Hang a weight 54 with a load W (for example, 100 g weight) on one thread 57, and connect the other thread 57 to the digital push-pull gauge 53. In this state, operate the linear motor 52 to pull the belt 56 through the thread 57, and read the value of the digital push-pull gauge 53 when the weight 54 starts to move. When this value is F (N), the static friction coefficient μ is calculated by the following formula. μ = (2 / π) × [ln(F / W)] (μ: static friction coefficient, π: pi, F: digital push gauge reading value, W: load)

[0038] The reason why the friction coefficient measured by the Euler belt method can be an index indicating the cleaning performance will be described based on the experimental results using the observation device of FIG. 7. FIG. 7 is a schematic configuration diagram of the observation device, and includes a transparent glass plate 58 and a high-speed camera 59. The high-speed camera 59 photographs the contact state at the nip portion N between the cleaning means 22b and the glass plate 58. In the figure, D1 indicates the moving direction of the glass plate 58, and D2 indicates the direction in which the cleaning means 22b in contact with the glass plate 58 rotates passively (is dragged). In addition, for the cleaning means 22b, a plurality of samples having different cleaning performances with respect to the charging roller 22a were prepared, and the relationship with the observation results was analyzed.

[0039] When the contact state at the nip between the roller-shaped cleaning means 22b and the glass plate 58 was observed with the observation device of FIG. 7, it was observed that a sample with excellent cleaning properties on the surface of the charging roller 22a was in close contact with the glass plate 58 and was actively moving at the nip as it rotated.

[0040] Also, it was observed that the higher the tackiness (adhesiveness) of the surface of the cleaning means 22b, the more active the movement of the cells in the foam that makes up the cleaning means 22b. The more active the movement of the cells, the more possible it is to remove the deposits on the surface of the charging roller 22a by random movement. Therefore, it is considered that the cleaning property is excellent and at the same time, it is difficult for dirt to accumulate on the same circumference, and the generation of streak-like dirt can be reduced.

[0041] FIG. 8 is a photograph showing an example of the observation result by the observation device of FIG. 7, and shows the cleaning means 22b that rotates passively as the glass plate 58 moves, photographed in the order of (A) and (B). The portions surrounded by the broken-line circles in FIGS. 8(A) and 8(B) are part of the skeletons that form the cells in the foam that constitutes the foam layer of the cleaning means 22b, and each shows the same location of the same cell (reference symbol C).

[0042] At the time shown in FIG. 8(A), the skeleton forming the cell adheres to the surface (gets caught) and the cell is compressed, and at the time shown in FIG. 8(B), the skeleton forming the cell separates from the surface and the cell is stretched. Such expansion and contraction of the cell become more active as the tackiness (adhesiveness) of the surface of the cleaning means 22b is higher. Since this tackiness represents the catchability with respect to the plane, the Euler belt method of measuring by sliding a paper belt can, in principle, measure this property, and the superiority or inferiority (good or bad) of the cleaning property can be expressed by the coefficient of friction.

[0043] Through a detailed examination of the following examples, it was found that when the value of the coefficient of friction by the Euler belt method is 0.5 or more, good cleaning performance can also be obtained for the actual charging roller 22a. Note that the upper limit of the coefficient of friction is not limited, and the higher the coefficient of friction, the better the cleaning performance, but the value that can be achieved with a resin foam member is generally 1.5 or less. In the cleaning device of the present invention, the static coefficient of friction on the surface of the foam layer 224 is 0.5 or more by the Euler belt method, and more preferably 0.6 or more. Further, in the cleaning device of the present invention, the static coefficient of friction on the surface of the foam layer 224 is preferably 0.5 or more and 0.79 or less by the Euler belt method.

[0044] The average thickness of the foam layer 224 is not particularly limited and can be appropriately selected according to the purpose, but 1 mm to 4 mm is preferable. If the average thickness of the foam layer 224 is less than 1 mm, it is easy to pick up the influence of the core material (shaft) 223, and if it exceeds 4 mm, the parts become larger and the degree of freedom in layout becomes lower. Note that the "average thickness" is the average value of the thicknesses measured at any three points of the foam layer 224.

[0045] Examples of the structure of the foam constituting the foam layer 224 include a mode having closed-cell type cells (see FIG. 9) and a mode having open-cell type cells (see FIG. 10). Open-cell type cells have a small compression residual strain and are likely to return to their original shape even when compressed, so they hardly deform even after long-term use. Therefore, a mode having open-cell type cells is preferable.

[0046] FIG. 9(A) is a photograph of an example of a foam having closed-cell type cells, and FIG. 9(B) is an explanatory diagram schematically showing a cross section. As shown in FIG. 9(B), the foam having closed-cell type cells has each cell C (hole) independent and has a structure that does not allow air or water to pass through. FIG. 10(A) is a photograph of an example of a foam having continuous bubble cells, and FIG. 10(B) is an explanatory diagram schematically showing a cross section. As shown in FIG. 10(B), in the foam having continuous bubble cells, adjacent cells C communicate with each other and have a structure that allows air and water to pass through. Therefore, the continuous bubble type is excellent in the action of sending the dirt adhering to the surface to be cleaned into the interior of the foam, and since it is difficult for dirt to accumulate on the surface, there is also an advantage that the cleaning performance can be maintained for a long period of time.

[0047] The number of cells included in the foam constituting the foam layer 224 is not particularly limited and can be appropriately selected according to the purpose, but 30 cells / inch to 150 cells / inch is preferable, and 50 cells / inch to 100 cells / inch is more preferable. If the number of cells is less than 50 cells / inch, the area of the cells in contact with the object to be cleaned may be too small to obtain sufficient cleaning performance. On the other hand, if it exceeds 100 cells / inch, the removed deposits tend to remain on the surface of the cleaning member, and the cleaning performance may deteriorate over time.

[0048] Note that the number of cells in the present embodiment is the average value of the values measured by the following method. A front view of the cleaning means 22b of the present embodiment to be measured is shown in FIG. 11. On the surface of the foam layer 224 of the cleaning means 22b in FIG. 11, three measurement locations are arbitrarily selected from the vicinity of both axial ends (reference numeral 40) and the central portion (reference numeral 41). Next, two different circumferential locations corresponding to each measurement location are further selected, and a total of nine measurement locations are determined.

[0049] For each of the determined measurement locations, a photograph is taken using a microscope, and the number of cells is measured from the obtained image. FIG. 12 is an explanatory diagram of the method for measuring the number of cells. As shown in FIG. 12, draw a line 42 at the center of the image, and count how many cells C are present within a length corresponding to an actual size of 1 inch (about 25 mm). Perform this for nine measurement locations and obtain the average value. Note that cells overlapping the 1-inch line 42 are counted even if only a part of the overlapping portion exists. For example, in the example shown in FIG. 12, the number of cells to be counted is 12.

[0050] The hardness of the foam constituting the foam layer 224 is not particularly limited and can be appropriately selected according to the purpose, but 50 N to 600 N is preferable, and 100 N to 500 N is more preferable. If the hardness of the foam is less than 100 N, the strength of the wall surface portion forming the cells is not sufficient, and the cleaning effect is slightly reduced. On the other hand, if the hardness of the foam exceeds 500 N, the polishing force by individual cells becomes high, and there is a risk of unevenly wearing the surface to be cleaned. Note that the hardness of the foam is the average value of the values measured based on JIS K 6400 at any three points on the surface of the foam layer.

[0051] The static friction coefficient of the surface of the above-mentioned foam layer, the form of the foam (closed-cell type / open-cell type), the number of cells contained in the foam, and the hardness of the foam can be controlled by appropriately adjusting the raw materials, the type and amount of the foaming agent, the reaction conditions during production, etc. when manufacturing the foam. As the foam, a resin foam is preferable, and in particular, a foamed polyurethane is preferable.

[0052] <Example> (Creation of Charging Device) In the charging device (corresponding to reference numeral 22 in FIG. 3) of a process cartridge having the same configuration as that shown in FIG. 3 (a photoreceptor unit manufactured by Ricoh Company, Ltd., copier RICOH IIM C5000), as a cleaning device, a cleaning means (corresponding to reference numeral 22b in FIG. 3) in which the foam layer is composed of foams A to O shown in Table 1 below was produced and installed. The dimensions of the cleaning means were made the same as those of the standard product of the process cartridge. The materials of Foams A to O, the cell mode (closed-cell type / open-cell type), the static friction coefficient (μ) of the surface, the hardness (N), and the number of cells (pieces / inch) are shown in accordance with Table 1. The conductive member of the charging roller (corresponding to the reference numeral 22a in FIG. 3) is formed of a hard resin mainly composed of ABS.

[0053]

Table 1

[0054] (Example 1) A process cartridge having a cleaning means composed of Foam A as a cleaning device of a charging device was attached to the black (K) station of an image forming apparatus (RICOH I IM C5000), and evaluation was performed using an actual machine as follows. In all cases, the black station was used alone.

[0055] In the cleaning of the charging roller, since it is disadvantageous that the consumption amount of the lubricant in the process cartridge is larger, the pressing force of the compression spring (corresponding to the reference numeral 27c in FIG. 3) of the lubricant application device (corresponding to the reference numeral 27 in FIG. 3) was set to twice the normal value, and an experiment was conducted by increasing the consumption amount of the lubricant. The printing conditions were continuous printing (paper passing) of a black vertical band chart up to 150,000 sheets in the A4 horizontal direction under a low temperature and low humidity environment (10 degrees, 15%), and the presence or absence of cleaning failure was confirmed.

[0056] The presence or absence of cleaning failure was determined by passing a blank sheet every 50,000 sheets and checking whether vertical black streaks (abnormal images) caused by charging roller contamination occurred on the image. When vertical black streaks occurred on the image, the process unit was taken out, and cleaning failure was determined by confirming that streak-like contamination occurred on the charging roller at the portion corresponding to the vertical black streaks on the image. The degree of the vertical black streaks was evaluated, and the cleaning performance was ranked in five levels. The best level was set to 5, the level acceptable in actual use was 3 or more, and the level unacceptable in actual use was 2 or less. The results are shown in Table 2.

[0057] (Examples 2 to 13) In Example 1, evaluation was performed in the same manner as in Example 1, except that the foam constituting the foam layer of the cleaning means was changed to Foams B to M. The results are shown in Table 2.

[0058] (Example 14) In Example 1, evaluation was performed in the same manner as in Example 1, except that the conductive member of the charging roller to be cleaned was changed to a rubber roller mainly composed of epichlorohydrin rubber. Note that the electrical characteristics and the like were adjusted so that factors other than the surface properties of the charging roller did not affect the evaluation results. The results are shown in Table 2.

[0059] (Comparative Examples 1 and 2) In Example 1, evaluation was performed in the same manner as in Example 1, except that the foam constituting the foam layer of the cleaning means was changed to Foams N and O. The results are shown in Table 2.

[0060] (Comparative Examples 3 and 4) In Example 14, evaluation was performed in the same manner as in Example 14, except that the foam constituting the foam layer of the cleaning means was changed to Foams N and O. The results are shown in Table 2.

[0061] [Table 2]

[0062] From the above results, in the cleaning device according to the present invention, the process cartridge including the cleaning device, and the image forming apparatus equipped with the same, it was shown that the dirt adhering to the charging roller can be removed uniformly and efficiently, and the occurrence of abnormal images mainly composed of vertical black streaks can be suppressed over a long period of time. On the other hand, in the comparative examples using the cleaning means having a static friction coefficient measured by the Euler belt method on the surface of the foam layer of less than 0.5, the occurrence of abnormal images was observed at an early stage.

[0063] In addition, in this embodiment, the charging roller was evaluated as the object to be cleaned. However, the object to be cleaned by the cleaning device according to the present invention is not limited as long as it is a rotating body that can be brought into contact with the surface for cleaning, and it is also applicable to the cleaning of the surface of a belt member such as a transfer belt, the cleaning of the surface of a photoreceptor drum, and the cleaning of the surface of a roller member such as a conveyance roller.

[0064] Aspects of the present invention are as follows, for example. <1> A cleaning device having cleaning means for contacting the surface of a rotating body and cleaning the surface of the rotating body, wherein the cleaning means is a roller member, includes a foam layer that contacts the surface of the rotating body, and the static friction coefficient measured by the Euler belt method on the surface of the foam layer is 0.5 or more. <2> The cleaning device according to <1>, wherein the foam constituting the foam layer includes a plurality of cells, and the number of the cells is 50 to 100 cells / inch. <3> The cleaning device according to <1> or <2>, wherein the hardness of the foam constituting the foam layer is 100 to 500 N. <4> The cleaning device according to any one of <1> to <3>, wherein the foam constituting the foam layer is a foamed polyurethane. <5> The cleaning device according to claim 4, wherein the foam has a closed-cell type cell structure. <6> The rotating body is a charged member, and the charged member is a charging roller including a conductive member made of a hard resin member and a conductive support member that rotatably supports the conductive member. <7> The cleaning device according to any one of <1> to <6>, wherein the static friction coefficient measured by the Euler belt method on the surface of the foam layer is 0.5 or more and 0.79 or less. <8> A latent image carrier that carries a latent image, Charging means for charging the surface of the latent image carrier by a charging member composed of a rotating body, In an image forming apparatus including at least a cleaning device having cleaning means for contacting the surface of the charging member and cleaning the surface of the charging member, The cleaning means is a roller member, and the roller member includes a foam layer that contacts the surface of the rotating body, An image forming apparatus characterized in that the static friction coefficient measured by the Euler belt method on the surface of the foam layer is 0.5 or more. <9> A latent image carrier for carrying a latent image, Charging means for charging the surface of the latent image carrier by a charging member composed of a rotating body, In an image forming apparatus including at least a cleaning device having cleaning means for contacting the surface of the charging member and cleaning the surface of the charging member, An image forming apparatus characterized by including the cleaning device according to any one of <1> to <7> as the cleaning device. <10> An image carrier for forming a latent image, Charging means for charging the surface of the image carrier by a charging member composed of a rotating body, In a process cartridge that includes at least a cleaning device having cleaning means for contacting the surface of the charging member and cleaning the surface of the charging member, and is detachable from the image forming apparatus main body, The cleaning means is a roller member, and the roller member includes a foam layer that contacts the surface of the rotating body, A process cartridge characterized in that the static friction coefficient measured by the Euler belt method on the surface of the foam layer is 0.5 or more. <11> An image carrier for forming a latent image, Charging means for charging the surface of the image carrier by a charging member composed of a rotating body, In a process cartridge that includes at least a cleaning device having cleaning means for contacting the surface of the charging member and cleaning the surface of the charging member, and is detachable from the image forming apparatus main body, The process cartridge is characterized in that it includes the cleaning device according to any one of <1> to <7>.

Explanation of Signs

[0065] 1 Image forming apparatus 10 Process cartridge 19 Pressing spring 21 Latent image carrier (photoconductor drum) 22 Charging device 22a Charging roller (charging member) 22b Cleaning means 224 Foam layer 223 Core material (shaft)

Prior Art Documents

Patent Documents

[0066]

Patent Document 1

Patent Document 2

Claims

1. A cleaning device having cleaning means for contacting the surface of a rotating body and cleaning the surface of the rotating body, wherein the cleaning means is a roller member, and includes a foam layer that contacts the surface of the rotating body, and the static friction coefficient measured by the Euler belt method on the surface of the foam layer is 0.5 or more. A cleaning device characterized by this.

2. The cleaning device according to claim 1, wherein the foam constituting the foam layer includes a plurality of cells, and the number of the cells is 50 to 100 cells / inch.

3. The cleaning device according to claim 1 or 2, wherein the hardness of the foam constituting the foam layer is 100 to 500 N.

4. The cleaning device according to claim 3, wherein the foam constituting the foam layer is a foamed polyurethane.

5. The cleaning device according to claim 4, wherein the foam has a continuous cell type cell.

6. wherein the rotating body is a charged member, The cleaning device according to claim 1 or 2, wherein the charged member is a charging roller including a conductive member made of a hard resin member and a conductive support member that rotatably supports the conductive member.

7. The cleaning device according to claim 1, wherein the static friction coefficient measured by the Euler belt method on the surface of the foam layer is 0.5 or more and 0.79 or less.

8. An image forming apparatus including at least: a latent image carrier that carries a latent image; charging means for charging the surface of the latent image carrier by a charging member composed of a rotating body; and a cleaning device having cleaning means for contacting the surface of the charging member and cleaning the surface of the charging member, wherein the cleaning means is a roller member, the roller member includes a foam layer that contacts the surface of the rotating body, and the static friction coefficient measured by the Euler belt method on the surface of the foam layer is 0.5 or more. An image forming apparatus characterized by this.

9. An image carrier for forming a latent image; charging means for charging the surface of the image carrier by a charging member composed of a rotating body; and a cleaning device having cleaning means for contacting the surface of the charging member and cleaning the surface of the charging member, and in a process cartridge that is detachable from the image forming apparatus main body. The cleaning means is a roller member, and the roller member includes a foam layer that contacts the surface of the rotating body. A process cartridge characterized in that a static friction coefficient measured by the Euler belt method on the surface of the foam layer is 0.5 or more.

Images