Image forming apparatus and process cartridge

Abstract

To reduce the occurrence of a trouble that, when a developing device is caused to serve also as a cleaning device, a foreign substance such as paper powder leaks to the outside of the developing device over time.SOLUTION: A developing device 5 is provided which is provided with a developing roller 51 that rotates in a predetermined rotation direction while in contact with a surface of a photoreceptor drum 1, and a supply roller 52 that rotates in the rotation direction while in contact with a surface of the developing roller 51. The developing roller 51 develops a latent image formed on the surface of the photoreceptor drum 1 to form a toner image, and recovers a toner attached to the surface of the photoreceptor drum 1. The supply roller 52 supplies a toner stored inside the developing device 5 to the surface of the developing roller 51, and recovers paper powder S (foreign substance) moving from the surface of the photoreceptor drum 1 to the surface of the developing roller 51 and attached to the surface of the developing roller.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to an image forming apparatus such as a copying machine, a printer, a facsimile machine, or a combination machine thereof, and a process cartridge installed therein. [Background technology]

[0002] Conventionally, among image forming devices such as copiers and printers, cleanerless types that do not include a cleaning device for cleaning untransferred toner adhering to the surface of a photosensitive member (photosensitive drum) have been known (see, for example, Patent Document 1). In such cleanerless image forming devices, untransferred toner adhering to the surface of the photosensitive member is collected by a developing device, which also functions as a cleaning device.

[0003] On the other hand, Patent Document 1 discloses a technology in which the developing roller and the supply roller rotate so as to move in the same direction at the contact point, in order to prevent problems such as paper dust getting caught between the developing roller and the regulating member (doctor blade) in a developing device installed in a cleanerless image forming device. Summary of the Invention [Problem to be solved by the invention]

[0004] The cleanerless image forming apparatus of Patent Document 1 suffers from a problem in which foreign matter such as paper dust that accumulates below the contact point between the developing roller and the supply roller inside the developing device leaks out of the developing device over time. In such cases, the foreign matter may re-adhere to the surface of the photosensitive drum or adhere to the optical elements of the exposure device, resulting in abnormal images.

[0005] The present invention has been made to solve the above-mentioned problems, and aims to provide an image forming apparatus and a process cartridge that are less likely to cause problems such as foreign matter such as paper dust leaking out of the developing device over time when the developing device is made to function as a cleaning device. [Means for solving the problem]

[0006] The image forming apparatus of this invention comprises a photosensitive body, a charging device that charges the surface of the photosensitive body, a developing device that has a developing roller that rotates in a predetermined rotational direction while in contact with the surface of the photosensitive body, and a supply roller that rotates in the same rotational direction while in contact with the surface of the developing roller, wherein the developing roller develops a latent image formed on the surface of the photosensitive body to form a toner image and collects toner that has adhered to the surface of the photosensitive body, and the supply roller supplies toner contained inside the developing device to the surface of the developing roller and collects foreign matter that has migrated from the surface of the photosensitive body to the surface of the developing roller and adhered thereto. [Effects of the Invention]

[0007] According to the present invention, it is possible to provide an image forming apparatus and a process cartridge that are less likely to experience the problem of foreign matter such as paper dust leaking out of the developing device over time when the developing device is made to function as a cleaning device. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is an overall configuration diagram showing an image forming apparatus according to an embodiment of the present invention; [Figure 2] FIG. 2 is a diagram illustrating a configuration of a process cartridge. [Figure 3] FIG. 3 is a schematic enlarged cross-sectional view of a part of the supply roller. [Figure 4] 10A and 10B are diagrams illustrating a state in which paper dust moves from the photosensitive drum into the inside of the developing device. [Figure 5]10A and 10B are diagrams illustrating, as a comparative example, a state in which paper dust moves from a photosensitive drum into the inside of a developing device. [Figure 6] FIG. 10 is a diagram showing a modified developing device. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In each drawing, the same or corresponding parts are designated by the same reference numerals, and redundant explanations will be appropriately simplified or omitted.

[0010] First, the overall configuration and operation of an image forming apparatus 100 will be described with reference to FIGS. In FIG. 1, 100 denotes a printer as an image forming device, 1 denotes a photosensitive drum as a photosensitive member on whose surface a toner image is formed, 6 denotes a process cartridge in which the photosensitive drum 1, a charging roller 3, and a developing device 5 are integrated, and 7 denotes an exposure device (writing device) that irradiates the photosensitive drum 1 with exposure light Lx based on image information input from an input device such as a personal computer. Also, 9 indicates a transfer roller that transfers the toner image carried on the surface of the photosensitive drum 1 onto a sheet P transported to the transfer nip portion (transfer position), and 12 indicates a paper feed device (paper feed cassette) that stores sheets P such as paper. Also, reference numeral 16 denotes a registration roller (timing roller) that conveys the sheet P toward the transfer nip portion where the photosensitive drum 1 and the transfer roller 9 abut, and 20 denotes a fixing device that fixes an unfixed image on the sheet P.

[0011] Here, a charging roller 3 and a developing device 5 are arranged around the photosensitive drum 1. These components (photosensitive drum 1, charging roller 3, and developing device 5) are integrated as a process cartridge 6, which is installed detachably (replaceably) with respect to the image forming apparatus main body 100. When the process cartridge 6 reaches a predetermined replacement cycle or when maintenance is performed, it is removed from the image forming apparatus main body 100 and replaced with a new one (or one that has been maintained).

[0012] 1 and 2, the operation of image forming apparatus 100 during normal image formation will be described. First, when image information is sent from an input device such as a personal computer to the exposure device 7 of the image forming apparatus 100, the exposure device 7 emits exposure light Lx (laser light) based on the image information toward the surface of the photosensitive drum 1. Meanwhile, photosensitive drum 1 receives drive from a drive motor installed in image forming apparatus main body 100 and rotates in the direction of the arrow (clockwise). First, the surface of photosensitive drum 1 is uniformly charged at the contact position with charging roller 3 (charging process). In this way, a charging potential (approximately -1100V) is formed on photosensitive drum 1. Note that toner adhering to charging roller 3 (untransferred toner) is removed by cleaning roller 4, which contacts charging roller 3. Thereafter, the charged surface of the photosensitive drum 1 reaches the position irradiated with the exposure light Lx. Then, the potential of the portion irradiated with the exposure light Lx becomes the latent image potential (approximately 0 to -100 V), and an electrostatic latent image is formed on the surface of the photosensitive drum 1 (exposure process).

[0013] Thereafter, the surface of the photosensitive drum 1 on which the electrostatic latent image has been formed reaches a position facing the developing device 5. Then, toner is supplied from the developing device 5 onto the photosensitive drum 1, and the latent image on the photosensitive drum 1 is developed to form a toner image (this is the developing process). Thereafter, the surface of the photosensitive drum 1 after the development process reaches a transfer nip portion (transfer position) with the transfer roller 9. Then, at the transfer nip portion with the transfer roller 9, a transfer bias (a bias with a polarity different from that of the toner) is applied from a power supply unit to the transfer roller 9, whereby the toner image formed on the photosensitive drum 1 is transferred onto the sheet P conveyed by the registration roller 16 (transfer process).

[0014] After the transfer step, the surface of the photosensitive drum 1 reaches a position facing the static eliminator 2, and residual potential is eliminated by static elimination light Lz irradiated from the static eliminator 2. Thereafter, the surface of the photosensitive drum 1 passes the position of the charging roller 3 and reaches a position facing the developing device 5. The developing device 5 then collects the toner (untransferred toner) remaining on the photosensitive drum 1 (cleaning process). In this way, the developing device 5 in this embodiment is configured to be able to collect the toner remaining on the surface of the photosensitive drum 1 (photosensitive element). In other words, the image forming apparatus 100 in this embodiment employs a cleanerless system. Thus, a series of image forming processes on the photosensitive drum 1 is completed.

[0015] On the other hand, the sheet P conveyed to the transfer nip portion between the photosensitive drum 1 and the transfer roller 9 operates as follows. First, the uppermost sheet of the sheets P stored in the sheet feeding device 12 is fed by the sheet feeding roller 15 toward the conveyance path. Thereafter, the sheet P reaches the position of the registration rollers 16. Then, the sheet P that has reached the position of the registration rollers 16 is transported toward the transfer nip portion (the position where the transfer roller 9 and the photosensitive drum 1 contact each other) in time to be aligned with the image formed on the photosensitive drum 1.

[0016] After the transfer process, the sheet P passes through the transfer nip portion (transfer roller 9) and then travels through a conveying path to reach the fixing device 20. The sheet P that has reached the fixing device 20 is fed between the fixing roller 21 and the pressure roller 22, where the image is fixed by the heat received from the fixing roller 21 and the pressure received from both members 21 and 22. The sheet P with the fixed image is sent out from between the fixing roller 21 and the pressure roller 22 (the fixing nip portion), and then discharged from the image forming apparatus main body 100 and placed on a paper output tray. In this way, a series of image forming processes is completed.

[0017] Next, the process cartridge 6 in the image forming apparatus 100 will be described in more detail with reference to FIG. As shown in FIG. 2, the process cartridge 6 mainly includes a photosensitive drum 1 as a photosensitive member, a charging roller 3 as a charging device, a cleaning roller 4 as a cleaning member for cleaning the surface of the charging roller 3, and a developing device 5, all of which are housed in a case. As explained above, the image forming unit in this embodiment is a cleanerless type image forming unit, and does not have a dedicated cleaning device (cleaning blade) for cleaning untransferred toner (residual toner) on the photosensitive drum 1, and the function of such a cleaning device is performed by the developing device 5.

[0018] The photosensitive drum 1 is a negatively charged organic photosensitive member, and is formed by providing a photosensitive layer on a drum-shaped conductive support. The photosensitive drum 1 is driven to rotate in the direction of the arrow (clockwise) in FIG. 2 by a drive motor (not shown). The charging roller 3, which serves as a charging device, is a roller member formed by covering the outer periphery of a conductive core with a medium-resistance elastic layer. A predetermined charging bias is applied to the charging roller 3 from a charging power source (not shown), thereby uniformly charging the surface of the opposing photosensitive drum 1. Note that the charging roller 3 (charging device) in this embodiment is configured to come into contact with the surface of the photosensitive drum 1 (photosensitive member). That is, the image forming apparatus 100 in this embodiment employs a contact charging system. The cleaning roller 4 functions as a cleaning member that comes into contact with the surface of the charging roller 3, and is made of brush bristles made of nylon or the like that are arranged around a core metal. In this embodiment, in order to improve the cleaning performance of the cleaning roller 4, a predetermined cleaning bias is applied to the cleaning roller 4 from a cleaning power source (not shown), so that the toner is electrostatically transferred from the charging roller 3 to the cleaning roller 4.

[0019] 2 and 4, the developing device 5 is arranged so that the developing roller 51, which serves as a developer carrier, is in contact with the photosensitive drum 1 with a predetermined pressure. Toner (a non-magnetic or magnetic one-component developer) is contained within the developing device 5. An electric field (developing electric field) is formed between the developing roller 51 and the photosensitive drum 1 (developing region), which develops the electrostatic latent image formed on the surface of the photosensitive drum 1 (forming a toner image). The electric field in the development area is formed by a predetermined development bias applied to the development roller 51 by the development power supply 91 and a surface potential (latent image potential) formed on the surface of the photosensitive drum 1 by the charging process and the exposure process.

[0020] The configuration and operation of the developing device 5 will be described in more detail below. 2 and 4, the developing device 5 in this embodiment is a contact single-component developing type developing device, and is installed as a component of the process cartridge 6 so as to be detachable (replaceable) with respect to the image forming apparatus main body 100. As shown in Figures 2 and 4, the developing device 5 is composed of a developing roller 51 as a developer carrier, a supply roller 52 as a supply rotor, a doctor blade 53 as a developer regulating member, an agitator 55 as an agitating member, and the like.

[0021] The developing roller 51 carries toner T (developer) on its surface and rotates in a predetermined direction (counterclockwise in FIG. 2) to supply the toner T to the electrostatic latent image formed on the photosensitive drum 1. In this embodiment, the developing roller 51 is disposed so as to contact the photosensitive drum 1. The developing roller 51 may be one having a core made of a conductive metal material such as stainless steel and an elastic layer made of a conductive elastic material on the core.

[0022] The supply roller 52 is in contact with the developing roller 51 . The supply roller 52 rotates in the same direction as the rotation direction of the developing roller 51 (counterclockwise in FIG. 2) to supply the toner T to the surface of the developing roller 51. In other words, the supply roller 52 is a roller member that supplies the toner T to the developing roller 51 while rotating in the counter direction relative to the rotation direction of the developing roller 51. The supply roller 52 has a shaft portion 52a (core metal) on which a foam layer 52b (having an electrical resistance of 10 MPa) is formed, such as from a conductive foam polyurethane. 3 ~10 14 Ω.) is formed. The supply roller 52 is formed so as to be able to remove foreign matter such as paper dust adhering to the surface of the developing roller 51, which will be described in detail later.

[0023] Although not shown, gears are provided on the shafts of the developing roller 51, the supply roller 52, and the agitator 55, and the gears are configured to mesh with each other. A driving force is input to these gear trains from a driving motor (not shown), and the developing roller 51 and the supply roller 52 are rotated in the directions of the arrows in FIGS. 2 and 4, respectively.

[0024] The doctor blade 53 (developer regulating member) is a thin plate-like member made of a metal material such as stainless steel, and is in contact with the developing roller 51 downstream of the supply roller 52 and upstream of the developing area. The doctor blade 53 regulates the amount of toner on the developing roller 51 to an appropriate amount. That is, the amount of toner (toner layer) supplied from the supply roller 52 onto the developing roller 51 is thinned at the position of the doctor blade 53.

[0025] The agitator 55 as an agitating member has a rotating shaft provided with a flexible, generally rectangular agitating portion made of Mylar or the like. The agitator 55 is used to agitate and transport the toner T contained inside the developing device 5 .

[0026] The developing device 5 configured as above operates as follows during a normal developing process. First, a portion of the toner T contained in the developing device 5 is drawn up (carried) onto the supply roller 52. Then, the toner T carried on the supply roller 52 is supplied onto the developing roller 51 in a frictionally charged state. Thereafter, the toner T' (which is in a frictionally charged state) carried on the developing roller 51 is thinned by the doctor blade 53 and then reaches a position (developing area) facing the photosensitive drum 1. At this position, the toner T' is attracted to the electrostatic latent image formed on the photosensitive drum 1 by an electric field (developing electric field) formed in the developing area. In this way, a desired toner image (image) is formed on the photosensitive drum 1. At this time, the toner T to be recovered (untransferred toner) carried on the photosensitive drum 1 is recovered onto the developing roller 51. That is, after passing through the development area, the surface of the developing roller 51 carries the untransferred toner T carried on the photosensitive drum 1 and the toner T' (undeveloped toner) that did not move onto the photosensitive drum 1 in the development process. Then, the toners T and T' carried on the developing roller 51 are returned into the developing device 5. In this embodiment, non-magnetic toner with a circularity of approximately 0.932 is used as the toner (developer) contained in the developing device 5. As the toner, non-spherical pulverized toner or polymerized toner can also be used. In this embodiment, negative polarity toner is used.

[0027] Here, a predetermined voltage is applied from a power supply to the developing roller 51, the supply roller 52, and the doctor blade 53, promoting electrostatic movement of the toner on the developing roller 51. In this embodiment, an alternating current voltage (a square wave with an AC frequency of about 500 to 1000 Hz, a peak-to-peak voltage of about 500 to 3000 V, and an application time duty of about 30 to 70%) is applied to the developing roller 51 so that the toner moves back and forth between the developing roller 51 and the photosensitive drum 1 in the development area. Although this embodiment is configured to apply an AC voltage to the developing roller 51, it is also possible to configure to apply a DC voltage of about −100 to −500 V to the developing roller 51.

[0028] In this embodiment, the following untransferred toner recovery operation is performed during printing (image formation) and when the image forming apparatus 100 is shut down. First, during printing (image formation), a potential difference widens between the charging roller 3 and the photosensitive drum 1, causing discharge before charging, and this discharge causes the untransferred toner on the photosensitive drum 1 to become negatively charged. However, the untransferred toner on the photosensitive drum 1 that is not negatively charged but remains positively charged adheres to the charging roller 3, and this positively charged toner is collected by the cleaning roller 4 due to the collection bias applied to the cleaning roller 4. Meanwhile, the negatively charged toner on the photosensitive drum 1 is collected by the developing device 5 (developing roller 51) due to the developing bias. In contrast, when the image forming apparatus 100 is shut down (when it is operating after printing is completed), the biases applied to the cleaning roller 4 and the charging roller 3 are varied to eject the toner on the cleaning roller 4 onto the photosensitive drum 1 via the charging roller 3, and the toner ejected onto the photosensitive drum 1 and carried thereon is collected by the developing device 5 (developing roller 51). At this time, the positively charged toner on the photosensitive drum 1 passes through the developing device 5 without being collected by the developing device 5, becomes negatively charged by discharge before charging, and is then collected by the developing device 5 (developing roller 51) by the developing bias.

[0029] The characteristic configuration and operation of the image forming apparatus 100 (process cartridge 6) according to this embodiment will be described in detail below. As previously explained using Figures 2, 4, etc., image forming apparatus 100 employs a cleanerless system. That is, image forming apparatus 100 is provided with a developing device 5 that includes a developing roller 51 that develops a latent image formed on the surface of photosensitive drum 1 as a photosensitive member to form a toner image and collects toner T adhering to the surface of photosensitive drum 1. Developing roller 51 rotates in a predetermined rotation direction (counterclockwise in Figure 4) while in contact with the surface of photosensitive drum 1 (photosensitive member). Furthermore, the supply roller 52 rotates in the same direction as the developing roller 51 (counterclockwise in FIG. 4) while in contact with the surface of the developing roller 51.

[0030] Here, in this embodiment, the supply roller 52 supplies the toner T contained inside the developing device 5 to the surface of the developing roller 51, and also collects foreign matter (including at least paper powder S) that has migrated from the surface of the photosensitive drum 1 (photosensitive body) to the surface of the developing roller 51 and adhered thereto.

[0031] 3 etc., the supply roller 52 has a shaft portion 52a on which a foam layer 52b made of a foamed resin material having a cell diameter W of 300 μm or more is formed. In particular, the foam layer 52b is made of a foamed resin material having a cell diameter W of 300 to 700 μm. In this embodiment, the cell diameter W is set to 300 μm. Here, in the present specification, the "cell diameter W" refers to the average diameter of the cells 52b1 (air bubbles) in the foamed resin material, and can be determined by methods such as image processing of a cross-sectional image obtained by cross-sectional observation. When the cross section of the cell 52b1 is elliptical, the cell diameter W is defined as the square root of the product of the major axis and the minor axis.

[0032] By setting the cell diameter W of the foam layer 52b (cells 52b1) of the supply roller 52 to 300 μm or more, paper powder S (foreign matter) that has migrated from the photosensitive drum 1 to the developing roller 51 can be easily captured inside the cells 52b1, thereby improving the paper powder collection ability (foreign matter collection ability) of the supply roller 52. Note that if the cell diameter W of the foam layer 52b (cells 52b1) is greater than 700 μm, the ability of the supply roller 52 to supply toner T to the developing roller 51 may be reduced, so it is preferable to set the cell diameter W within the range of 300 to 700 μm.

[0033] In the present embodiment, the foam layer 52b (cells 52b1) has an open cell shape. That is, a plurality of cells 52b1 are formed on the outer peripheral surface of the foam layer 52b, and are configured to be in direct contact with the surface of the developing roller 51. This improves the function of the supply roller 52 in collecting paper dust S (foreign matter) on the developing roller 51.

[0034] In this embodiment, the supply roller 52 rotates (the rotation speed is set) so that the linear velocity ratio of the supply roller 52 to the developing roller 51 at the portion where the supply roller 52 contacts the developing roller 51 is 1.0 or more. In particular, it is preferable to set the linear velocity ratio to be within the range of 1.0 to 1.5. In this embodiment, the linear velocity ratio is set to 1.2. By setting the linear velocity ratio of the supply roller 52 to the developing roller 51 to 1.0 or more, the frictional force between the supply roller 52 and the developing roller 51 can be maintained at a relatively high level, thereby ensuring the ability to scrape off paper dust S on the developing roller 51. If the linear velocity ratio of supply roller 52 to developing roller 51 exceeds 1.5, the frictional force between supply roller 52 and developing roller 51 becomes too large, resulting in an excessive increase in drive torque. Therefore, it is preferable to set the linear velocity ratio within the range of 1.0 to 1.5.

[0035] Hereinafter, the operation of collecting paper dust S (foreign matter) in the developing device 5 in this embodiment will be described with reference to FIG. Since the image forming apparatus 100 in this embodiment employs a cleanerless system, when paper dust S from the sheet P adheres to the surface of the photosensitive drum 1 at the transfer nip, the paper dust S is conveyed directly to the opposing position A (developing area) with the developing roller 51 (developing device 5). Then, at the opposing position A, the paper dust S on the photosensitive drum 1 moves onto the developing roller 51. The paper powder S that has moved onto the developing roller 51 is collected at a high collection rate at the contact point B with the supply roller 52 by the supply roller 52, which has a cell diameter W set to 300 μm or more and a linear velocity ratio of 1.0 or more. The paper powder S collected by the supply roller 52 is then separated from the supply roller 52, or moved again to the developing roller 51, and then scraped off by the doctor blade 53 in area C, and is collected inside the developing device 5.

[0036] Therefore, the problem of paper dust S (foreign matter) leaking out of the developing device 5 over time is less likely to occur. When a supply roller 152 that does not have a function for collecting paper dust S (or a supply roller 152 with a low ability to collect paper dust S), such as a developing device 150 shown as a comparative example in FIG. 5, is used, the paper dust S on the developing roller 51 is scraped off and accumulates below the contact point between the developing roller 51 and the supply roller 152 (area D) inside the developing device 5. Then, as the amount of paper dust S accumulated in area D increases over time, the paper dust S leaks out of the developing device 5 (moving in the direction of the white arrow). In such a case, the leaked paper dust S (foreign matter) may re-adhere to the surface of the photosensitive drum 1, or the leaked and scattered paper dust S (foreign matter) may adhere to the optical elements of the exposure device 7, resulting in abnormal images. In contrast, in this embodiment, a supply roller 52 having a high ability to collect paper dust S is used, so that paper dust S hardly remains below the contact point between the developing roller 51 and the supply roller 152 (area D), and the problem of paper dust S leaking from area D to the outside of the developing device 5 is less likely to occur. In particular, by optimizing the biases applied to the developing roller 51, the supply roller 52, and the doctor blade 53 to match the polarity of the paper dust S, it is possible to promote the movement of the paper dust S from the photosensitive drum 1 to the supply roller 52 via the developing roller 51, and further to promote the movement of the paper dust S from the supply roller 52 to the doctor blade 53 via the developing roller 51. In this embodiment, the life (replacement cycle) of the developing device 5 (process cartridge 6) is set to be relatively short so as not to exceed 20,000 printed sheets. Therefore, even if the collected paper dust S accumulates in the area C (near the doctor blade 53), the accumulated paper dust S is less likely to adhere to the doctor blade 53.

[0037] The inventors of the present application conducted an experiment to confirm the number of printed sheets at which paper dust S leaked outside the developing device 5 when continuously printing using the image forming device 100 under the following four conditions. The inventors confirmed that the number of printed sheets increased from 6,000 sheets, to 10,000 sheets, to 15,000 sheets, to 30,000 sheets under conditions 1 to 4, in that order, and that the effect of reducing the leakage of paper dust S improved. Condition 1) Cell 52b1 is a closed cell, the cell diameter is 150 μm, and the linear velocity ratio is 0.7. Condition 2) Cell 52b1 is open cell, cell diameter is 200 μm, and linear velocity ratio is 0.7. Condition 3) Cell 52b1 is open cell, cell diameter is 300 μm, and linear velocity ratio is 0.7. Condition 4) Cell 52b1 is open cell, cell diameter is 300 μm, and linear velocity ratio is 1.2.

[0038] <Modification> As shown in Figure 6, the developing device 5 in the modified example is provided with a scraping member 56 that scrapes out paper powder S (foreign matter) that has accumulated near the doctor blade 53 (developer regulating member) (area C) toward a position away from the accumulation position (area C). More specifically, the scraping member 56 is attached to the rotation shaft of an agitator 55 (agitation member) that agitates the toner T contained inside the developing device 5, and rotates together with the agitator 55 in the counterclockwise direction in FIG. The scraping member 56 is made of a flexible resin material such as Mylar, and is formed so that the tip extending from the base held by the rotating shaft of the agitator 55 reaches the area C. In addition, the scraping member 56 is bent in multiple ways (bending downstream in the direction of rotation) from the base to the tip, so that the paper dust S accumulated in the area C can be efficiently scraped out. By providing the scraping member 56 in this manner, even if the life (replacement cycle) of the developing device 5 (process cartridge 6) is set to be relatively long, the collected paper dust S is less likely to remain in area C (near the doctor blade 53), and the problem of the paper dust S adhering to the doctor blade 53 is less likely to occur.

[0039] As described above, the image forming apparatus 100 (process cartridge 6) in this embodiment includes the photosensitive drum 1 (photosensitive member) and the charging roller 3 (charging device) that charges the surface of the photosensitive drum 1. The image forming apparatus 100 also includes the developing device 5, which includes the developing roller 51 that rotates in a predetermined rotational direction while in contact with the surface of the photosensitive drum 1, and the supply roller 52 that rotates in the same rotational direction while in contact with the surface of the developing roller 51. The developing roller 51 develops the latent image formed on the surface of the photosensitive drum 1 to form a toner image, and collects toner adhering to the surface of the photosensitive drum 1. The supply roller 52 supplies toner stored in the developing device 5 to the surface of the developing roller 51, and also collects paper dust S (foreign matter) that has migrated from the surface of the photosensitive drum 1 to the surface of the developing roller 51 and adhered thereto. This makes it possible to prevent the problem of foreign matter such as paper dust S leaking out of the developing device 5 over time when the developing device 5 is made to function as a cleaning device.

[0040] In this embodiment, the present invention is applied to a case where the photosensitive drum 1 (photosensitive member), charging roller 3 (charging device), and developing device 5 are integrated into a process cartridge 6. However, the application of the present invention is not limited to this, and the present invention can also be applied to a case where these components are individually configured as units that are detachably attached to the image forming apparatus main body 100 (not constituting a process cartridge). Even in such a case, the same effects as those of the present embodiment can be obtained. In this application, a "process cartridge" is defined as a unit that integrates at least one of a charging device that charges a photosensitive member and a developing device that develops a latent image formed on the photosensitive member, with a photosensitive member, and is detachably installed in the image forming apparatus main body.

[0041] Furthermore, in this embodiment, the present invention is applied to a monochrome image forming apparatus 100 in which a toner image is transferred onto a sheet P by one image forming unit (process cartridge 6). However, the present invention can also be applied to a color image forming apparatus in which a toner image is primarily transferred onto an intermediate transfer body such as an intermediate transfer belt by multiple image forming units, and then the toner image is secondarily transferred from the intermediate transfer body onto a sheet. In such a case, the same effect as that of this embodiment can be obtained.

[0042] It is to be noted that the present invention is not limited to the present embodiment, and it is clear that the present embodiment can be appropriately modified within the scope of the technical concept of the present invention in addition to the modifications suggested in the present embodiment. Furthermore, the number, position, shape, etc. of the components are not limited to the present embodiment, and the number, position, shape, etc. of the components can be any number, position, shape, etc. that is suitable for implementing the present invention. [Explanation of symbols]

[0043] 1 Photosensitive drum (image carrier), 3. Charging roller (charging device), 4 cleaning roller (cleaning member), 5 developing device, 6 Process cartridge, 51 developing roller (developer carrier), 52 supply roller (developer supply member), 52a shaft, 52b foam layer (elastic layer), 52b1 cell (bubble), 53 Doctor blade (developer control member), 55 agitator (agitation member), 56 scraping member, 100 Image forming apparatus (image forming apparatus main body), S paper dust (foreign matter), T, T' toner (developer), W cell diameter.

[0044] The present invention can also be embodied in a combination of Supplementary Notes 1 to 8, as follows. (Appendix 1) A photoreceptor; a charging device that charges the surface of the photoreceptor; a developing device including a developing roller that rotates in a predetermined rotation direction while in contact with the surface of the photosensitive member, and a supply roller that rotates in the predetermined rotation direction while in contact with the surface of the developing roller; Equipped with the developing roller develops the latent image formed on the surface of the photosensitive member to form a toner image, and collects the toner adhering to the surface of the photosensitive member; An image forming apparatus characterized in that the supply roller supplies toner contained inside the developing device to the surface of the developing roller and collects foreign matter that has migrated from the surface of the photosensitive body to the surface of the developing roller and adhered thereto. (Appendix 2) The supply roller A foam layer made of a foamed resin material having a cell diameter of 300 μm or more is formed on the shaft portion, 2. The image forming apparatus according to claim 1, wherein the developing roller is rotated so that the linear velocity ratio at the portion of contact with the developing roller is 1.0 or more. (Appendix 3) 3. The image forming apparatus according to claim 2, wherein the foam layer has an open cell shape. (Appendix 4) the foam layer is made of a foamed resin material having a cell diameter of 300 to 700 μm, 4. The image forming apparatus according to claim 2, wherein the linear velocity ratio is 1.0 to 1.5. (Appendix 5) 5. The image forming apparatus according to claim 1, wherein the foreign matter includes at least paper powder. (Appendix 6) The developing device is a developer regulating member that regulates the amount of toner supplied by the supply roller and carried on the surface of the developing roller; a scraping member that scrapes out the foreign matter that has accumulated near the developer regulating member toward a position away from the accumulation position; 6. The image forming apparatus according to claim 1, further comprising: (Appendix 7) 7. The image forming apparatus according to claim 6, wherein the scraping member is installed in an agitating member that agitates the toner contained inside the developing device. (Appendix 8) A process cartridge that is detachably installed in an image forming apparatus main body, A photoreceptor; a charging device that charges the surface of the photoreceptor; a developing device including a developing roller that rotates in a predetermined rotation direction while in contact with the surface of the photosensitive member, and a supply roller that rotates in the predetermined rotation direction while in contact with the surface of the developing roller; Equipped with the developing roller develops the latent image formed on the surface of the photosensitive member to form a toner image, and collects the toner adhering to the surface of the photosensitive member; A process cartridge characterized in that the supply roller supplies toner contained inside the developing device to the surface of the developing roller and collects foreign matter that has migrated from the surface of the photosensitive body to the surface of the developing roller and adhered thereto. [Prior art documents] [Patent documents]

[0045] [Patent Document 1] Japanese Patent Publication No. 2023-75865

Claims

1. A photoreceptor; a charging device that charges the surface of the photoreceptor; a developing device including a developing roller that rotates in a predetermined rotation direction while in contact with the surface of the photosensitive member, and a supply roller that rotates in the predetermined rotation direction while in contact with the surface of the developing roller; Equipped with the developing roller develops the latent image formed on the surface of the photosensitive member to form a toner image, and collects the toner adhering to the surface of the photosensitive member; An image forming apparatus characterized in that the supply roller supplies toner contained inside the developing device to the surface of the developing roller and collects foreign matter that has migrated from the surface of the photosensitive body to the surface of the developing roller and adhered thereto.

2. The supply roller A foam layer made of a foamed resin material having a cell diameter of 300 μm or more is formed on the shaft portion, 2. The image forming apparatus according to claim 1, wherein the developing roller is rotated so that the linear velocity ratio at the contact portion with the developing roller is 1.0 or more.

3. 3. The image forming apparatus according to claim 2, wherein the foam layer has open cells.

4. the foam layer is made of a foamed resin material having a cell diameter of 300 to 700 μm, 3. The image forming apparatus according to claim 2, wherein the linear velocity ratio is 1.0 to 1.

5.

5. 3. The image forming apparatus according to claim 1, wherein the foreign matter includes at least paper dust.

6. The developing device is a developer regulating member that regulates the amount of toner supplied by the supply roller and carried on the surface of the developing roller; a scraping member that scrapes out the foreign matter that has accumulated near the developer regulating member toward a position away from the accumulation position; 3. The image forming apparatus according to claim 1, further comprising:

7. 7. The image forming apparatus according to claim 6, wherein the scraping member is provided in an agitating member that agitates the toner contained inside the developing device.

8. A process cartridge that is detachably installed in an image forming apparatus main body, A photoreceptor; a charging device that charges the surface of the photoreceptor; a developing device including a developing roller that rotates in a predetermined rotation direction while in contact with the surface of the photosensitive member, and a supply roller that rotates in the predetermined rotation direction while in contact with the surface of the developing roller; Equipped with the developing roller develops the latent image formed on the surface of the photosensitive member to form a toner image, and collects the toner adhering to the surface of the photosensitive member; A process cartridge characterized in that the supply roller supplies toner contained inside the developing device to the surface of the developing roller and collects foreign matter that has migrated from the surface of the photosensitive body to the surface of the developing roller and adhered thereto.

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