Cartridge and image forming apparatus

Abstract

To provide an image forming apparatus that further develops conventional technology. [Solution] A cartridge comprising a photosensitive drum unit and a developing unit detachably mounted to the photosensitive drum unit, wherein the photosensitive drum unit comprises a photosensitive drum that rotates around a first rotation axis, a charging wire, a cleaning member for cleaning the surface of the photosensitive drum, a wire electrode disposed on the end face of the photosensitive drum unit, and a cleaning electrode disposed on the end face, and the developing unit comprises a developing roller that rotates around a second rotation axis, wherein, when viewed in the direction of the first rotation axis, the wire electrode and the cleaning electrode are positioned on opposite sides of each other with respect to a virtual straight line passing through the first rotation axis and the second rotation axis.

Description

Technical Field

[0001] The present invention relates to a cartridge used in an image forming apparatus and an image forming apparatus that forms an image on a recording material.

Background Art

[0002] Patent Document 1 describes a drum cartridge including a photosensitive drum, a scorotron type charger, and a cleaning unit. This drum cartridge is provided with two electrodes electrically connected to the charging wire and grid of the charger, respectively, and two electrodes electrically connected to the primary roller and secondary roller of the cleaning unit, respectively.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] An object of the present invention is to provide an image forming apparatus that further develops the prior art.

Means for Solving the Problems

[0005] One aspect of the present invention is a cartridge having a photosensitive drum unit and a developing unit detachably mounted to the photosensitive drum unit, wherein the photosensitive drum unit has a photosensitive drum that rotates around a first rotation axis, a charging wire for charging the surface of the photosensitive drum, a cleaning member for cleaning the surface of the photosensitive drum, a wire electrode disposed on one end face of the photosensitive drum unit in the direction of the first rotation axis and electrically connected to the charging wire, and a cleaning electrode disposed on the end face and electrically connected to the cleaning member, wherein the developing unit has a developing roller that rotates around a second rotation axis and supplies developer to the photosensitive drum, and the wire electrode and the cleaning electrode are arranged on opposite sides of each other with respect to a virtual straight line passing through the first rotation axis and the second rotation axis when viewed in the direction of the first rotation axis. [Effects of the Invention]

[0006] According to the present invention, it is possible to provide an image forming apparatus that further develops the prior art. [Brief explanation of the drawing]

[0007] [Figure 1] A schematic cross-sectional view of an image forming apparatus according to an embodiment. [Figure 2] Perspective views (a, b) of the apparatus body according to the embodiment. [Figure 3] A schematic cross-sectional view of a drum cartridge and a developing cartridge according to an embodiment. [Figure 4] Figures (a, b) show the operation of attaching and detaching the drum cartridge according to the embodiment. [Figure 5] Perspective views (a, b) showing a drum cartridge and a developing cartridge according to an embodiment. [Figure 6] Cross-sectional view of a drum cartridge and a developing cartridge according to an embodiment. [Figure 7] Perspective views (a, b) showing the configuration of the charging unit according to the embodiment. [Figure 8]A side view (a) and a perspective view (b) of the right end of the developing cartridge according to the embodiment. [Figure 9] Figures (a-e) show the configuration of the right end of the drum cartridge according to the embodiment. [Figure 10] Figures (a, b) show the support configuration of the cleaning roller and the collection roller according to the embodiment. [Figure 11] Figures (a-c) showing the contacts of the cartridge and the main body of the device according to the embodiment. [Figure 12] A diagram showing the contact arrangement of the drum cartridge and developing cartridge according to the embodiment. [Modes for carrying out the invention]

[0008] The following describes an image forming apparatus 100 according to one embodiment of this disclosure.

[0009] In the following description and drawings, the vertical direction (direction of gravity and its opposite direction) when the image forming apparatus 100 is installed on a horizontal surface is defined as the up-down direction. The direction of the rotation axis of the photosensitive drum 411 (image carrier) of the image forming apparatus 100 is defined as the left-right direction. The direction perpendicular to both the up-down and left-right directions is defined as the front-back direction. Furthermore, "left," "right," "front," and "back" are based on the directions shown in Figure 1.

[0010] Figure 1 is a cross-sectional view of the image forming apparatus 100 cut by a virtual plane perpendicular to the left-right direction. Figures 2(a) and 2(b) are perspective views of the apparatus body 1.

[0011] As shown in Figure 1, the image forming apparatus 100 includes an apparatus body 1, a feeding unit 2, a transport unit 3, an image forming unit 4, a fixing unit 5, a discharge unit 6, and a loading unit 7. The apparatus body 1 is a housing that accommodates the feeding unit 2, the transport unit 3, the image forming unit 4, the fixing unit 5, and the discharge unit 6, and includes a frame and exterior. The feeding unit 2 is located at the bottom of the apparatus body 1. The transport unit 3 is located at the front of the apparatus body 1. The image forming unit 4 is located in the center of the apparatus body 1. The fixing unit 5 and the discharge unit 6 are located at the rear of the apparatus body 1. The loading unit 7 is located at the top of the apparatus body 1.

[0012] At least a part of the image forming unit 4 is configured as a unit (process cartridge 4P) detachable from the apparatus main body 1. Details of the process cartridge 4P will be described later.

[0013] The feeding unit 2 is an example of a feeding means for feeding a recording material S (recording medium). The conveying unit 3 is an example of a conveying means for conveying the recording material S from the feeding unit 2 to the image forming unit 4. The image forming unit 4 is an example of an image forming means for forming an image on the recording material S. The fixing unit 5 is an example of a fixing means for fixing the image formed on the recording material S. The discharging unit 6 is an example of a discharging means for conveying the recording material S on which the image is fixed to the stacking unit 7. The stacking unit 7 is an example of a stacking means for stacking the recording material S on which image formation has been performed.

[0014] The image forming apparatus 100 is capable of executing an image forming operation of forming an image on the recording material S by an electrophotographic process while conveying the recording material S. In the image forming operation, the recording material S is fed from the feeding unit 2, conveyed to the image forming unit 4 by the conveying unit 3, and an image is formed (a developer image is transferred) by the image forming unit 4. The recording material S on which the image has been formed is conveyed to the fixing unit 5 and undergoes a fixing process of the image. Further, the recording material S on which the image has been fixed is discharged to the outside of the apparatus main body 1 via the discharging unit 6 and stacked in the stacking unit 7.

[0015] [Feeding Unit and Conveying Unit] The feeding unit 2 and the conveying unit 3 will be described with reference to FIG. 1. The feeding unit 2 of the present embodiment includes a cassette 20 and a pickup unit 21. The cassette 20 is a storage unit in which the recording material S is stacked and stored. As the recording material S, various sheet materials of different sizes and materials can be used, such as paper such as plain paper and thick paper, sheet materials with surface treatment such as coated paper, sheet materials with special shapes such as envelopes and index paper, plastic films, cloth, etc. The pickup unit 21 is a unit that picks up and feeds the recording materials S one by one from the cassette 20. The pickup unit 21 is, for example, arranged above a middle plate that is vertically movable in the cassette 20, and is a feeding roller that contacts and rotates with the uppermost recording material S on the middle plate.

[0016] The conveying unit 3 includes an upstream conveying roller pair 30, a conveying guide 31, a downstream conveying roller pair 32, and a conveying paper dust collecting unit 33. The upstream conveying roller pair 30 is a roller pair that receives the recording material S from the feeding unit 2 and further conveys it. The conveying guide 31 is a guide that regulates the movement path of the recording material S. The downstream conveying roller pair 32 is a roller that conveys the recording material S to the image forming unit 4.

[0017] The conveying paper dust collecting unit 33 is a unit that collects paper dust (foreign matter) from the recording material S conveyed toward the image forming unit 4. The paper dust here is a general term for paper fibers, fillers, dust attached to the paper, etc. The conveying paper dust collecting unit 33 includes a paper dust adsorption roller 331, a scraper 332, and a paper dust collection container 333. The paper dust adsorption roller 331 also serves as one of the rollers of the upstream conveying roller pair 30. The paper dust adsorption roller 331 contacts the recording material S being conveyed and electrostatically adsorbs the paper dust. The scraper 332 scrapes the paper dust adsorbed on the paper dust adsorption roller 331. The paper dust collection container 333 collects the scraped paper dust.

[0018] The downstream conveying roller pair 32 is composed of a first conveying roller 321 and a second conveying roller 322. In the present embodiment, the first conveying roller 321 is provided in the apparatus main body 1, and the second conveying roller 322 is provided in the drum cartridge 41. In the present embodiment, the second conveying roller 322 rotates following the first conveying roller 321 that is rotationally driven by a drive source provided in the apparatus main body 1. However, the second conveying roller 322 may itself be a roller that is rotationally driven by a drive source.

[0019] The operation of the feeding unit 2 and the transport unit 3 during the image forming operation will now be explained. When the image forming operation starts, the pickup unit 21 of the feeding unit 2 and the upstream transport roller pair 30 and downstream transport roller pair 32 of the transport unit 3 are rotated by the driving force of the drive source provided in the main body of the device 1. The pickup unit 21 feeds the recording material S from the cassette 20 one sheet at a time. The fed recording material S is transported toward the transfer unit of the image forming unit 4 by the upstream transport roller pair 30 and the downstream transport roller pair 32. Alternatively, the recording material S transported by the upstream transport roller pair 30 may be brought into contact with the stationary downstream transport roller pair 32 to correct its skew, and transport by the downstream transport roller pair 32 may be started at a timing that matches the operation of the image forming unit 4.

[0020] [Image Forming Unit] Next, the image forming unit 4 will be explained using Figures 1 and 2(a) and 2(b). As shown in Figure 1, the image forming unit 4 includes a process cartridge 4P and a laser scanner unit 40. The process cartridge 4P includes a drum cartridge 41 (photosensitive drum unit) containing a photosensitive drum 411 and a developing cartridge 42 (developing unit). Also, as shown in Figure 2(a), a bias generation unit 14 is located on the right side of the main body 1 of the apparatus, serving as a bias generation means (voltage generation unit) that generates various high voltages (bias voltages) for use in the electrophotographic process and applies them to the image forming unit 4. The bias generation unit 14 is a high-voltage board on which a voltage generation circuit is mounted that generates various high voltages by receiving power from an external power supply (commercial power supply) to which the image forming apparatus 100 is connected.

[0021] The laser scanner unit 40 is an exposure device (latent image forming unit) for exposing the photosensitive drum 411, which is an image carrier, to write a latent image. In the image forming operation, the control unit of the image forming apparatus 100 processes, for example, image information received from the outside, to generate a signal (video signal) for driving the laser scanner unit 40. Based on the video signal, the laser scanner unit 40 irradiates the photosensitive drum 411 with laser light L and writes a latent image (electrostatic latent image) on the surface of the photosensitive drum 411. The exposure device may also be an LED exposure device that uses a number of LEDs arranged in the direction of the rotation axis of the photosensitive drum 411 as a light source.

[0022] The bias generation unit 14 generates various high voltages based on commands from the control unit of the image forming apparatus 100. As will be described later, the bias generation unit 14 is electrically connected to the targets to which the various high voltages are applied, which are provided on the process cartridge 4P, via contact between the contacts of the apparatus body 1 and the contacts of the process cartridge 4P. The voltage values ​​of the various high voltages generated by the bias generation unit 14 and the timing of the start / stop of application are controlled by the control unit of the image forming apparatus 100.

[0023] As shown in Figure 1, the drum cartridge 41 includes a photosensitive drum 411, a charging unit 412, a transfer roller 413, a cleaning unit 414, and a second transport roller 322. The photosensitive drum 411 is an image carrier that holds the toner image. The photosensitive drum 411 has a cylindrical metal base including a drum shaft 4111, and a photosensitive layer formed of an organic photosensitive material or the like on the outer circumference of the base. The drum shaft 4111 of the photosensitive drum 411 is rotatably supported by the frame of the drum cartridge 41.

[0024] The charging unit 412 is a charging means for applying an electrical charge to the photosensitive drum 411. The transfer roller 413 is a transfer means for transferring the toner image supported on the photosensitive drum 411 to the recording material S. The cleaning unit 414 is a cleaning means for cleaning foreign matter such as paper dust (hereinafter referred to as residue) adhering to the photosensitive drum 411.

[0025] The developing cartridge 42 includes a developing roller 421, a developing blade 422, a supply roller 423, a transport paddle 424, and a toner storage section 425. The developing roller 421 is a toner carrier (developer carrier) that carries toner as a developer. The developing roller 421 is a developing member that, when a predetermined bias is applied, supplies the carried toner to the photosensitive drum 411, thereby developing the electrostatic latent image into a toner image. The developing blade 422 is a regulating means that regulates the thickness of the toner layer carried by the developing roller 421. The supply roller 423 is a supply means that supplies toner to the developing roller 421. The transport paddle 424 is a toner transport means that transports toner to the supply roller 423. The toner storage section 425 is a toner storage means that stores toner.

[0026] The charging unit 412 in this embodiment is a scorotron-type charger. That is, the charging unit 412 has a charging wire 4121 (corona discharge wire) and a grid plate 4126. The charging bias generated by the bias generation unit 14 is applied to the charging wire 4121. The grid bias generated by the bias generation unit 14 is applied to the grid plate 4126. Then, the corona discharge caused by these biases charges the surface of the photosensitive drum 411.

[0027] The toner contained in the toner storage section 425 is transported by the transport paddle 424 toward the supply roller 423, and supplied to the developing roller 421 by the supply roller 423. The toner carried on the developing roller 421 has its layer thickness regulated by the developing blade 422 and is charged by triboelectric charging. The developing roller 421 is subjected to a developing bias generated by the bias generation section 14. The toner carried on the developing roller 421 is transferred from the developing roller 421 to the photosensitive drum 411 according to the potential difference between the potential of the developing roller 421 to which the developing bias has been applied (developing potential) and the potential of the electrostatic latent image formed on the photosensitive drum 411.

[0028] For example, in the inverted development method, a charging bias of the same polarity as the normal polarity of the toner is applied to the charging wire 4121, and the surface of the photosensitive drum 411 is charged to a potential (dark area potential) of the same polarity as the normal polarity of the toner. The laser scanner unit 40 irradiates the area where an image should be formed (image area) with laser light L, and lowers the surface potential of the photosensitive drum 411 in the image area to a bright area potential closer to 0V than the dark area potential. The development potential is set between the dark area potential and the bright area potential. Therefore, in the development section where the development roller 421 and the photosensitive drum 411 face each other, toner is transferred from the development roller 421 to the image area on the photosensitive drum 411, while toner does not transfer to areas other than the image area (non-image area) and remains on the development roller 421. As a result, a toner image is formed on the surface of the photosensitive drum 411 while it is passing through the development section.

[0029] The toner image formed on the photosensitive drum 411 is transferred from the photosensitive drum 411 to the recording material S as the recording material S, transported from the transport unit 3, passes through the transfer unit of the image forming unit 4 (the nip formed between the photosensitive drum 411 and the transfer roller 413). A transfer bias generated by the bias generation unit 14 is applied to the transfer roller 413. The transfer bias is set to a voltage value with the opposite polarity to the normal polarity of the toner.

[0030] Furthermore, any residual materials such as paper dust that has moved from the recording material S to the photosensitive drum 411 as the recording material S passes through the transfer section, and toner that was not transferred to the recording material S (transfer residue toner), are cleaned from the surface of the photosensitive drum 411 by the cleaning section 414.

[0031] [Fixing section] Next, the fixing unit 5 will be explained using Figure 1. The fixing unit 5 includes a fixing frame 50, a heating roller 51, and a pressure roller 52.

[0032] The fixing frame 50 is a frame for unitizing the fixing unit 5. The fixing frame 50 rotatably supports the heating roller 51 and the pressure roller 52. The heating roller 51 is a heating element that heats the toner image on the recording material S. The fixing unit 5 has a heat source for heating the heating roller 51. The heat source is, for example, a halogen lamp placed inside the heating roller 51. The pressure roller 52 is a pressure element that forms a nip (fixing nip) by being pressed against the heating roller 51. The heating roller 51 or the pressure roller 52 is rotationally driven by a drive source located in the main body 1 of the device.

[0033] The fixing unit 5 heats and pressurizes the toner image on the recording material S while transporting it by gripping it with fixing nip using pressure rollers 52 and pressure rollers 52. The heating and pressurizing softens the toner, and then it fixes to the recording material S, thereby obtaining an image fixed to the recording material S.

[0034] [Discharge section and loading section] Next, the discharge section 6 and the loading section 7 will be explained using Figure 1. The discharge section 6 includes a transport roller pair 60, a transport guide 61, and a discharge roller pair 62. The loading section 7 includes a discharge opening 70 and a discharge tray 71. The transport roller pair 60 and the discharge roller pair 62 are transport members that transport the recording material S. The transport guide 61 is a guide means that guides the transport path of the recording material S.

[0035] The transport roller pair 60 and the discharge roller pair 62 are rotationally driven by a drive source provided in the device body 1. The recording material S that has passed through the fixing section 5 is transported by the transport roller pair 60. The transport guide 61 guides the recording material S being transported by the transport roller pair 60 toward the discharge roller pair 62. The discharge roller pair 62 is positioned in a discharge opening 70, which is an opening provided on the outer surface of the device body 1. The discharge roller pair 62 grips and transports the recording material S and discharges it from the inside to the outside of the device body 1 through the discharge opening 70. The discharged recording material S is loaded onto a discharge tray 71.

[0036] [Processing cartridge] Next, the process cartridge 4P will be described using Figure 3. Figure 3 is a schematic cross-sectional view of the process cartridge 4P. As mentioned above, the process cartridge 4P of this embodiment consists of a drum cartridge 41 and a developer cartridge 42.

[0037] In addition to the elements described above, the drum cartridge 41 has a drum frame 410. The elements of the drum cartridge 41 described above (photosensitive drum 411, charging section 412, transfer roller 413, cleaning section 414, second transport roller 322) are supported by the drum frame 410. In other words, the drum cartridge 41 is a unit in which the drum frame 410 and the multiple elements supported by the drum frame 410 are integrated.

[0038] As the image forming operation is repeated, the photosensitive drum 411, transfer roller 413, etc., gradually deteriorate. Also, any residue cleaned by the cleaning unit 414 is collected inside the cleaning unit 414. In other words, as the image forming operation is repeatedly performed, the elements of the drum cartridge 41 deteriorate, or the available capacity in the cleaning unit 414 decreases, and the drum cartridge 41 reaches the end of its replacement period. Since the drum cartridge 41 is detachably attached to the main body 1 of the device, the user can easily replace the drum cartridge 41.

[0039] In addition to the elements described above, the developing cartridge 42 has a developing frame 420. The elements of the developing cartridge 42 described above (developing roller 421, developing blade 422, supply roller 423, transport paddle 424, toner storage section 425) are supported by the developing frame 420. In other words, the developing cartridge 42 is a unit in which the developing frame 420 and the multiple elements supported by the developing frame 420 are integrated.

[0040] As the image forming operation is repeated, the developing roller 421, supply roller 423, etc., gradually deteriorate. Also, the toner that was filled in the toner storage unit 425 is consumed. In other words, as the image forming operation is repeatedly performed, the elements of the developing cartridge 42 deteriorate, or the toner in the toner storage unit 425 is depleted, and the developing cartridge 42 reaches the end of its replacement period. Since the developing cartridge 42 is configured to be detachable from the main unit 1 of the device, the user can easily replace the developing cartridge 42.

[0041] Furthermore, as shown in Figure 3, a developing press member 415 (pressing member) and a developing pressure spring 416 (biasing member) are assembled to the drum frame 410. In other words, the drum cartridge 41 has a developing press member 415 and a developing pressure spring 416.

[0042] The developing press member 415 contacts the pressure receiving surface 4201 formed on the developing frame 420. The developing pressure spring 416 biases the developing press member 415. Due to the biasing force of the developing pressure spring 416, the developing cartridge 42 is pressed in the direction in which the developing roller 421 moves toward the photosensitive drum 411 (the direction in which the rotation axis A2 of the developing roller 421 approaches the rotation axis A1 of the photosensitive drum 411). As a result, when the developing cartridge 42 is mounted on the drum cartridge 41, the developing roller 421 contacts the photosensitive drum 411 with appropriate contact pressure.

[0043] [Removing and installing process cartridges] Next, the attachment and detachment of the drum cartridge 41 will be explained using Figures 2(a)(b), 4(a)(b), and 5(a)(b). In this embodiment, the developing cartridge 42 is attached to the drum cartridge 41 and then attached to and detached from the device body 1 together with the drum cartridge 41. Therefore, the following can also be described as the attachment and detachment of the process cartridge 4P to the device body 1.

[0044] Figures 2(a) and 2(b) are perspective views of the main body 1 of the device. Figure 2(a) shows the state in which the cartridge door 11, which will be described later, is closed. Figure 2(b) shows the state in which the cartridge door 11 is open and the drum cartridge 41 is outside the main body 1 of the device. Figures 4(a) and 4(b) are schematic diagrams showing the operation of attaching and detaching the drum cartridge 41 to the main body 1 of the device. Figure 4(a) shows the state in which the drum cartridge 41 is outside the main body 1 of the device, and Figure 4(b) shows the state in which the drum cartridge 41 is installed in the main body 1 of the device. Figures 5(a) and 5(b) are perspective views showing the drum cartridge 41 and the developing cartridge 42. Figure 5(a) shows the state in which the drum cartridge 41 and the developing cartridge 42 are separated, and Figure 5(b) shows the state in which the drum cartridge 41 and the developing cartridge 42 are combined.

[0045] As shown in Figure 2(a), a cartridge door 11 is provided on the front of the device body 1 as an opening and closing member. The cartridge door 11 is movable between an open position (Figure 2(b)) that opens the cartridge opening 12 provided in the device body 1 and a closed position (Figure 2(a)) that closes the cartridge opening 12.

[0046] As shown in Figure 2(a), when the cartridge door 11 is in the closed position, it is possible to prevent light and foreign matter from entering from the outside. By opening the cartridge door 11, the cartridge opening 12 is exposed. By opening the cartridge door 11, the user can attach and detach the drum cartridge 41 (attach and detach the process cartridge 4P) through the cartridge opening 12. In addition, by opening the cartridge door 11 and removing the drum cartridge 41 from the device body 1, it becomes possible to remove the recording material S that has accumulated inside the device body 1 due to a transport malfunction (jam) (jam processing).

[0047] Furthermore, the main body of the device 1 is provided with cartridge guide grooves 121. The cartridge guide grooves 121 are formed in the left and right inner walls 120 of the main body of the device 1, which form the storage space for the process cartridge 4P. The cartridge guide grooves 121 engage with a portion of the drum cartridge 41 and act as guides that restrict the movement trajectory of the drum cartridge 41 relative to the main body of the device 1.

[0048] As shown in Figure 2(b), a drum positioning pin 4100 and a drum guide pin 4101 are located on the right side of the drum frame 410. Similar drum positioning pins and drum guide pins are also located on the left side of the drum frame 410. The drum positioning pin 4100 is a positioning pin used to determine the position of the drum cartridge 41 relative to the device body 1. The drum guide pin 4101 is a posture restricting pin that controls the posture of the drum cartridge 41 when attaching or detaching it from the device body 1.

[0049] As shown in Figure 4(a), a cartridge positioning section 122 is formed at the rear end of the cartridge guide groove 121. The cartridge positioning section 122 is a positioning section for positioning the drum cartridge 41 on the device body 1.

[0050] As shown in Figure 4(a), when the drum cartridge 41 is mounted on the device body 1, the drum cartridge 41 is inserted into the device body 1 through the cartridge opening 12. During insertion, the drum positioning pin 4100 and the drum guide pin 4101 are engaged with the cartridge guide groove 121. The engagement of the drum positioning pin 4100 and the drum guide pin 4101 with the cartridge guide groove 121 restricts the direction of movement and orientation of the drum cartridge 41. As shown in Figure 4(b), mounting of the drum cartridge 41 is completed when the drum cartridge 41 is inserted to a position where the drum positioning pin 4100 contacts the cartridge positioning part 122.

[0051] To remove the drum cartridge 41 from the main unit 1 of the device, simply move the drum cartridge 41 in the opposite direction to how it was installed.

[0052] In addition to replacing the drum cartridge 41 or the developing cartridge 42, the drum cartridge 41 is also removed from the main unit 1 when jamming. Since the developing cartridge 42 in this embodiment is attached to and detached from the main unit 1 together with the drum cartridge 41, there is an advantage in that jamming is easier compared to a configuration in which, for example, the developing cartridge 42 is attached to and detached from the main unit 1 independently of the drum cartridge 41.

[0053] [Attaching and detaching the developing cartridge] Next, the attachment and detachment of the developing cartridge 42 will be explained using Figures 2(a)(b), 3, and 5(a)(b).

[0054] As shown in Figure 5(a), development guide grooves 4102 are formed in the left and right inner walls 120 of the drum frame 410. As shown in Figure 5(a), a development positioning pin 4200 is formed on the right side of the development frame 420. Furthermore, a pressure receiving surface 4201 is formed at the rear of the development frame 420. One pressure receiving surface 4201 is provided near both the left and right ends of the development frame 420. Also, as shown in Figure 3, a development pressing member 415 and a development pressure spring 416 are assembled at the front of the drum frame 410 at positions opposite to each pressure receiving surface 4201.

[0055] The developing guide groove 4102 is a guide portion for guiding the attachment and detachment of the developing cartridge 42 to and from the drum cartridge 41. The developing pressing member 415 and the developing pressure spring 416 are pressurizing means for pressing the developing roller 421 against the photosensitive drum 411. The developing positioning pin 4200 is a positioning means for positioning the developing cartridge 42 relative to the drum cartridge 41. The pressure receiving surface 4201 is a contact portion that contacts the developing pressing member 415.

[0056] The groove width of the developing guide groove 4102 is set to a size that allows the developing positioning pin 4200 to engage. The developing pressure spring 416 is set to press the developing roller 421 against the photosensitive drum 411 with a predetermined pressure.

[0057] When attaching the developing cartridge 42 to the drum cartridge 41, align the developing guide groove 4102 with the developing positioning pin 4200. Then, move the developing cartridge 42 towards the photosensitive drum 411. Next, push the pressure receiving surface 4201 of the developing frame 420 downward toward the developing pressing member 415. This completes the attachment of the developing cartridge 42 to the drum cartridge 41. To detach the developing cartridge 42 from the drum cartridge 41, perform the operation in the reverse order of the above.

[0058] The following describes a detailed configuration example of the process cartridge 4P according to this embodiment, using Figures 2(a) and 2(b), and Figures 6 to 12. Note that the specific numerical values ​​of the bias voltage in the following description are merely examples and can be changed as needed.

[0059] [Charging section] The charging section 412 of this embodiment will be described using Figures 6 and 7(a) and 7(b). Figure 6 is a cross-sectional view showing a part of the cross-section of the drum cartridge 41 and the developing cartridge 42. Figures 7(a) and 7(b) are visual diagrams illustrating the configuration of the charging section 412. Figure 7(a) is an enlarged perspective view of the right side of the drum cartridge 41. Figure 7(b) is a perspective view showing the state in which the charging section 412 is exposed from the state in Figure 7(a). In Figures 6 and 7(a) and 7(b), broken lines are indicated by dashed lines.

[0060] As shown in Figure 6, the charging unit 412 includes a charging wire 4121 and a grid plate 4126. The charging wire 4121 is a discharge member for generating corona discharge. By applying a charging bias generated by the bias generation unit 14 to the charging wire 4121, corona discharge occurs, and the surface of the photosensitive drum 411 is charged. The grid plate 4126 is an adjustment member that has the function of adjusting the surface potential of the photosensitive drum 411 which is charged by corona discharge. By applying a grid bias generated by the bias generation unit 14 to the grid plate 4126, the surface potential of the photosensitive drum 411 can be made uniform and stabilized.

[0061] For example, a charging bias of approximately +4500V is applied to the charged wire 4121, and a grid bias of approximately +800V is applied to the grid plate 4126. This applies a charging treatment to the photosensitive drum 411, enabling the formation of a good image.

[0062] Next, the configuration of the charging unit 412 will be described using Figures 7(a) and 7(b). As shown in Figure 7(a), the drum frame 410, which is the frame of the drum cartridge 41, includes an upper drum frame 4104, a lower drum frame 4105, and a drum side cover 4103. The upper drum frame 4104 and the lower drum frame 4105 are fastened to each other and extend in the left-right direction. The drum side cover 4103 is attached to the right ends of the upper drum frame 4104 and the lower drum frame 4105. The charging unit 412 is incorporated into the upper drum frame 4104.

[0063] The drum side cover 4103 is a cover member that constitutes at least a part of the end face (right side) of one end of the drum cartridge 41. The outer surface (right-facing side) of the drum side cover 4103 has a wire electrode opening 41031 in which the wire electrode 4124 is exposed, and a grid electrode opening 41032 in which the grid electrode 4128 is exposed.

[0064] Furthermore, a drum shaft positioning hole 41037 is formed on the outer surface of the drum side cover 4103, through which the drum shaft 4111 passes. The drum shaft 4111 protrudes to the right of the outer surface of the drum side cover 4103. The tip of the drum shaft 4111 functions as a drum electrode (contact point with the ground portion of the device body 1) for connecting the conductive substrate of the photosensitive drum 411 to the ground potential.

[0065] The charged wire 4121 is a wire that extends in the left-right direction. The wire material can be selected from tungsten, stainless steel, etc. In this embodiment, tungsten wire is used. Tungsten wire is a material with excellent heat resistance and corrosion resistance. Since a high-voltage charging bias is applied to the charged wire 4121, tungsten wire is one of the suitable materials.

[0066] The grid plate 4126 is made of a thin metal sheet. Specifically, stainless steel or plated steel sheets can be selected. A mesh section 4127 is also formed on the grid plate 4126. The mesh section 4127 is made by mesh processing on a metal sheet. Methods for mesh processing include etching and pressing. Etching is a processing method that allows for free setting of the mesh pattern. Pressing is a processing method that limits the degree of freedom of the mesh pattern, but is inexpensive. The mesh processing method can be appropriately selected from these methods. By providing the mesh section 4127, ions generated by corona discharge can pass through the voids in the mesh section 4127.

[0067] As shown in Figure 7(b), with the drum side cover 4103 removed, the right side of the charged portion 412 is exposed.

[0068] A positioning hole 41041 is formed on the right end face of the upper drum frame 4104. The upper frame positioning hole 41041 is a positioning part. The upper frame positioning hole 41041 engages with the drum shaft 4111 (Figure 7(a)) that supports the photosensitive drum 411, thereby positioning the upper drum frame 4104 and the photosensitive drum 411.

[0069] Furthermore, a wire support section 4129 and a wire spring support section 41042 are formed on the right side of the upper drum frame 4104. The wire support section 4129 is a support section that supports the charged wire 4121. The wire spring support section 41042 is a support section that supports the wire spring 4123. A V-shaped groove section 41291 is formed in the wire support section 4129. The V-shaped groove section 41291 is a defining section that defines the distance between the charged wire 4121 and the photosensitive drum 411.

[0070] A wire terminal 4122 is placed at the end of the charged wire 4121. The wire terminal 4122 is a metal terminal and is crimped onto the charged wire 4121.

[0071] The wire spring 4123 is a tension-applying member that applies a predetermined tension to the charged wire 4121. The wire spring 4123 has a wire electrode 4124, a wire engagement portion 4125, and a spring connection portion 41231. The wire electrode 4124 is an electrode (contact portion with the electrical circuit of the device body 1) for applying a bias to the wire spring 4123. The wire engagement portion 4125 is an engagement portion that engages with the wire terminal 4122. The spring connection portion 41231 is a connection portion that connects the wire spring 4123 and the wire electrode 4124. The wire electrode 4124 is electrically connected to the charged wire 4121 via the spring connection portion 41231 and the wire engagement portion 4125.

[0072] In other words, the wire spring 4123 combines the function of a tension-applying member that applies tension to the charged wire 4121 and the function of an electrode for applying a charge bias to the charged wire 4121. However, the tension-applying member and the electrode for applying a charge bias to the charged wire 4121 may be separate members.

[0073] A grid electrode 4128 is formed at the right end of the grid plate 4126. The grid electrode 4128 is an electrode (contact point with the electrical circuit of the device body 1) for applying a bias to the grid plate 4126. A grid connection part 41261 is also formed on the grid plate 4126. The grid connection part 41261 is a connection part that connects the mesh part 4127 of the grid plate 4126 to the grid electrode 4128. When the grid plate 4126 is assembled into the drum upper frame 4104, the grid electrode 4128 is located to the right of the right end face of the drum upper frame 4104. The grid electrode 4128 is electrically connected to the mesh part 4127 of the grid plate 4126 via the grid connection part 41261. Note that the electrode for applying the grid bias to the mesh part 4127 of the grid plate 4126 may be an independent component rather than part of the grid plate 4126.

[0074] Here, the grid connection portion 41261 extends forward relative to the mesh portion 4127, and the spring connection portion 41231 extends backward relative to the wire engagement portion 4125 and the coil portion of the wire spring 4123. Therefore, on the right side of the drum cartridge 41, the wire electrode 4124 and the grid electrode 4128 can be positioned further apart in the front-rear direction, making it easier to secure the distance between the electrodes.

[0075] The wire spring 4123 is supported by the wire spring support portion 41042. The wire engagement portion 4125 engages with the wire terminal 4122. The charged wire 4121 is subjected to a predetermined tension by the elastic force of the wire spring 4123. Furthermore, the elastic force of the spring allows for stable electrical connection between the wire terminal 4122 and the wire engagement portion 4125. When the wire spring 4123 is incorporated into the drum upper frame 4104, the wire electrode 4124 is positioned to the right of the right end face of the drum upper frame 4104.

[0076] Furthermore, the wire spring 4123 is positioned to pull the wire terminal 4122 downwards and to the right. Consequently, the charged wire 4121 is pulled towards the lowest point of the V-shaped groove 41291. This configuration makes it possible to restrict a predetermined distance from the charged wire 4121 to the photosensitive drum 411.

[0077] In this way, the upper drum frame 4104 contributes to the relative positioning of the charging section 412 and the photosensitive drum 411. Specifically, the upper drum frame 4104 is positioned relative to the drum axis 4111, and the charging wire 4121 is positioned relative to the upper drum frame 4104. The upper drum frame 4104 also supports members to which a high-voltage bias is applied, such as the charging wire 4121 and the grid plate 4126.

[0078] Furthermore, a wire electrode 4124 and a grid electrode 4128, which are electrodes to which a high-voltage bias is applied, are located on the right side of the drum cartridge 41. In case of leakage current occurring near the electrodes to which the high-voltage bias is applied, for example, the drum upper frame 4104 and the drum side cover 4103 may be made of flame-retardant resin material. The drum upper frame 4104, drum lower frame 4105, and drum side cover 4103 may be made of self-extinguishing resin.

[0079] For example, a charging bias of approximately +4500V is applied to the charged wire 4121, and a bias of approximately +800V is applied to the grid plate 4126. The wire electrode 4124 and the grid electrode 4128 are configured to maintain distance between the electrodes in the front-rear direction by a grid connection part 41261 and a wire spring 4123. Furthermore, the wire electrode 4124 and the grid electrode 4128 are electrodes for applying high-voltage bias. Therefore, it is preferable to use flame-retardant resin for the drum upper frame 4104 that supports the charging section 412.

[0080] The wire electrode 4124 only needs to be electrically connected to the charged wire 4121, and may be a separate component from, for example, the wire spring 4123. The grid electrode 4128 only needs to be electrically connected to the mesh portion 4127 of the grid plate 4126, and may be a separate component from, for example, the grid plate 4126. The wire electrode 4124 and the grid electrode 4128 may be resin molded products formed as part of the drum frame 410 by two-color molding using a conductive resin material, for example. The conductive resin material is a resin material that has been imparted conductivity by dispersing a conductive filler such as carbon black in a base resin.

[0081] [Developing cartridge] Next, the developing cartridge 42 will be described using Figures 6 and 8(a) and 8(b). Figures 8(a) and 8(b) are enlarged views showing the right side of the developing cartridge 42. Figure 8(a) is a view showing the right side of the developing cartridge 42. Figure 8(b) is a perspective view showing the right side of the developing cartridge 42. In Figures 8(a) and 8(b), the broken lines are indicated by dashed lines.

[0082] As shown in Figure 6, a toner storage section 425 is formed inside the developing frame 420 of the developing cartridge 42, and a transport paddle 424 is positioned in the toner storage section 425. The transport paddle 424 is driven counterclockwise in the figure by the drive source of the device body 1, and transports the toner from the toner storage section 425 toward the supply roller 423. The supply roller 423 is, for example, a sponge roller with a sponge covering a shaft. The supply roller 423 is driven clockwise in the figure by the drive source of the device body 1. The toner transported by the transport paddle 424 is taken into the sponge layer of the supply roller 423.

[0083] The developing roller 421 is, for example, a rubber roller with a rubber coating on a shaft. The developing roller 421 is driven to rotate clockwise in the figure by the drive source of the main body of the device 1. The developing roller 421 and the supply roller 423 are in contact such that the sponge layer of the supply roller 423 is compressed by a predetermined amount. In other words, at the contact point between the supply roller 423 and the developing roller 421, the supply roller 423 rubs against the surface of the developing roller 421 in a counter-clockwise direction while the sponge layer of the supply roller 421 is compressed by the developing roller 421. As a result, the toner that was taken into the supply roller 423 is discharged from the sponge layer and carried on the surface of the developing roller 421. In addition, the supply roller 423 can remove old toner from the surface of the developing roller 421 when the compressed sponge layer recovers its volume.

[0084] The developing blade 422 is a thin metal plate, and the tip that contacts the developing roller 421 may be bent. The developing blade 422 contacts the developing roller 421 with a predetermined contact pressure. The toner supported on the developing roller 421 is restricted to a predetermined layer thickness as it passes through the nip portion of the developing blade 422. In addition, the toner supported on the developing roller 421 is charged by frictional charging as it is rubbed by the developing blade 422.

[0085] The charge bias and grid bias are set, for example, so that the surface potential of the photosensitive drum 411, which has been charged by the charging unit 412, is approximately +800V (hereinafter referred to as the dark area potential VD). In the area irradiated by the laser beam L from the laser scanner unit 40 (image area), the surface potential of the photosensitive drum 411 is approximately +100V (hereinafter referred to as the bright area potential VL). The developing roller 421 carries toner that has been given a positive charge. In addition, a developing bias of approximately +500V generated by the bias generation unit 14 is applied to the developing roller 421. Therefore, the toner carried on the developing roller 421 adheres to the area of ​​the photosensitive drum 411 with a bright area potential VL (image area) and does not adhere to the area of ​​the dark area potential VD (non-image area).

[0086] Meanwhile, a supply bias of approximately +650V generated by the bias generation unit 14 is applied to the supply roller 423. Since the potential difference between the development bias and the supply bias is approximately 150V, the positively charged toner moves from the supply roller 423 to the development roller 421. This potential difference also has the effect of increasing the proportion of positively charged toner in the toner carried by the development roller 421.

[0087] Next, the electrode configuration of the developing cartridge 42 will be explained using Figures 8(a) and 8(b). As shown in Figure 8(a), a developing side cover 4202 is provided on the right side of the developing cartridge 42. The developing side cover 4202 constitutes the right end face of the developing frame 420.

[0088] The developing side cover 4202 houses a developing power supply member 426 and a supply power supply member 427. The developing power supply member 426 is electrically connected to the developing roller 421. The supply power supply member 427 is electrically connected to the supply roller 423. The developing power supply member 426 is a conductive member for applying a developing bias to the developing roller 421. The supply power supply member 427 is a conductive member for applying a supply bias to the supply roller 423.

[0089] The developing power supply member 426 of this embodiment includes a developing electrode 4261 and a developing sliding part 4262. The developing electrode 4261 is an electrode (contact point with the electrical circuit of the device body 1) to which the developing bias generated by the bias generation unit 14 is supplied. The developing sliding part 4262 is a sliding part that slides against the shaft of the developing roller 421. The supply power supply member 427 of this embodiment includes a supply electrode 4271 and a supply sliding part 4272. The supply electrode 4271 is an electrode (contact point with the electrical circuit of the device body 1) to which the supply bias generated by the bias generation unit 14 is supplied. The supply sliding part 4272 is a sliding part that slides against the shaft of the supply roller 423.

[0090] In this embodiment, the developing electrode 4261 and the supply electrode 4271 are integrally formed with the developing sliding portion 4262 and the supply sliding portion 4272, respectively. In other words, since the developing power supply member 426 and the supply power supply member 427 of this embodiment have sliding portions that slide against the shaft, a conductive resin material of a high grade with good sliding properties can be selected. However, the developing electrode 4261 and the supply electrode 4271 only need to be electrically connected to the developing roller 421 and the supply roller 423, respectively, and may be separate parts from the developing sliding portion 4262 and the supply sliding portion 4272.

[0091] As shown in Figure 8(b), the developing electrode 4261 and the supply electrode 4271 have a shape that protrudes to the right from the developing side cover 4202.

[0092] As described above, the developing cartridge 42 is equipped with a developing electrode 4261 and a supply electrode 4271. A developing bias of approximately +500V is applied to the developing roller 421 via the developing electrode 4261. A supply bias of approximately +650V is applied to the supply roller 423 via the supply electrode 4271.

[0093] [Cleaning Department] Next, the cleaning unit 414 will be explained using Figures 2(a) and 2(b), Figure 6, and Figures 9(a) to 10(b).

[0094] Figures 9(a) to 9(e) show the configuration of the right side of the drum cartridge 41. Figure 9(a) shows the drum cartridge 41 before the drum side cover 4103 and cleaning bearing 4146 are assembled. Figure 9(b) shows only the cleaning roller 4141 and recovery roller 4142 from Figure 9(a). Figure 9(c) shows the drum cartridge 41 after the cleaning bearing 4146 has been assembled from the state in Figure 9(a). Figure 9(d) shows only the cleaning roller 4141 and recovery roller 4142 from Figure 9(c). Figure 9(e) shows the drum cartridge 41 with the drum side cover 4103 assembled from the state in Figure 9(c). In Figures 9(a) to 9(e), broken lines are indicated by dashed lines.

[0095] Figures 10(a) and 10(b) illustrate the support of the cleaning roller 4141 and the recovery roller 4142 by the drum side cover 4103. Figure 10(a) is a side view of the drum side cover 4103 viewed from the left. Figure 10(b) is a magnified perspective view of the right side of the drum cartridge 41. In Figures 10(a) and 10(b), broken lines are represented by dashed lines. In Figure 10(b), the drum side cover 4103 is represented by a double-dash line to show the interior of the drum cartridge.

[0096] As shown in Figure 6, the cleaning unit 414 includes a cleaning roller 4141, a recovery roller 4142, a sealing member 4143, a scraping member 4144, and a recovery chamber 4145.

[0097] The cleaning roller 4141 is a cleaning member that cleans the photosensitive drum 411. The cleaning roller 4141 contacts the photosensitive drum 411 at a position downstream of the transfer section and upstream of the charging section 412 in the rotational direction of the photosensitive drum 411, and collects residue remaining on the surface of the photosensitive drum 411. The recovery roller 4142 is a recovery member that collects paper dust from the residue cleaned by the cleaning roller 4141. The scraping member 4144 scrapes off the paper dust collected by the recovery roller 4142. The recovery chamber 4145 contains the paper dust scraped off by the scraping member 4144. The sealing member 4143 prevents the paper dust collected in the recovery chamber 4145 from leaking to the outside.

[0098] The cleaning roller 4141 is, for example, a sponge roller having a metal shaft and a sponge layer. The sponge material can be selected from foamed rubber with high resistance, such as ethylene propylene rubber, urethane rubber, or silicone rubber. The sponge material is preferably selected considering cost, ease of processing, hardness, weather resistance, chemical resistance, electrostatic properties, and resistance. In this embodiment, foamed silicone rubber is used. By using foamed silicone rubber, the elastic force properties do not change much over a long period of time, which can extend the lifespan of the drum cartridge 41.

[0099] The cleaning roller 4141 is rotationally driven by a drive source provided in the main body of the device 1. The rotation direction of the cleaning roller 4141 may be forward (clockwise in Figure 6) relative to the rotation direction of the photosensitive drum 411 (counterclockwise in Figure 6).

[0100] The recovery roller 4142 is, for example, a metal roller. The recovery roller 4142 is in contact with the cleaning roller 4141 and is rotationally driven by a drive source provided in the main body of the device 1. The rotation direction of the recovery roller 4142 may be forward relative to the rotation direction of the cleaning roller 4141 (counterclockwise in Figure 6).

[0101] The scraping member 4144 is, for example, a rubber member fixed to the drum upper frame 4104. The rubber material can be selected from urethane rubber, silicone rubber, etc. In this embodiment, the scraping member 4144 is set so that its corners contact the recovery roller 4142. This makes it possible to more effectively scrape off paper dust adhering to the recovery roller 4142. If the scraping capacity of the scraping member 4144 can be reduced, such as when the overall lifespan of the drum cartridge 41 is set to be shorter, the scraping member 4144 may be, for example, a less expensive foamed urethane sheet.

[0102] The recovery chamber 4145 is a space formed by the upper drum frame 4104 and the lower drum frame 4105. By utilizing the space formed by joining different frames in this way as the recovery chamber 4145, it is not only less expensive than a configuration that uses a separate dedicated frame, but it is also possible to create a larger space.

[0103] The sealing member 4143 consists of two sheet members attached to the upper drum frame 4104 and the lower drum frame 4105, respectively. The sheet material can be selected from PET, urethane rubber, etc. Because the PET sheet has a smooth surface, paper dust adhering to the recovery roller 4142 can easily move to the recovery chamber 4145. On the other hand, because the urethane rubber sheet has low elasticity, it is possible to reduce the contact pressure between the sheet and the roller. One end of the sealing member 4143 in the shorter direction is fixed to the frame, and the other end is in contact with the surface of the cleaning roller 4141, thereby sealing the gap formed between the cleaning roller 4141 and the frame.

[0104] Next, we will explain how to recover the residue remaining on the photosensitive drum 411 using Figure 6. First, we will explain the transfer bias applied to the transfer roller 413.

[0105] The drum cartridge 41 has a transfer electrode 4131 that is electrically connected to the transfer roller 413. The transfer electrode 4131 is an electrode (contact point with the electrical circuit of the device body 1) that is electrically connected to the main body transfer contact 138 of the device body 1. A transfer bias of approximately -2000V is applied to the transfer roller 413 by the bias generation unit 14 (Figure 2(a)) via the main body transfer contact 138 and the transfer electrode 4131. When the toner image supported on the photosensitive drum 411 passes through the nip (transfer section) between the photosensitive drum 411 and the transfer roller 413, it is transferred to the recording material S by the action of the bias electric field generated by the application of the transfer bias to the transfer roller 413. At that time, the surface potential of the photosensitive drum 411 decreases in both the image area and the non-image area due to the action of the transfer bias.

[0106] As the recording material S passes through the transfer section, any negatively charged particles, such as paper dust, present on the surface of the recording material S move to the surface of the photosensitive drum 411. Consequently, the surface of the photosensitive drum 411 after passing through the transfer section contains residual paper dust and toner that was not transferred to the recording material S (transfer residue toner).

[0107] A cleaning bias of approximately +500V is applied to the cleaning roller 4141. If the surface potential of the photosensitive drum 411 is close to 0V than the cleaning bias, negatively charged residues such as paper dust can be collected by the cleaning roller 4141. In this case, positively charged residues such as toner are not collected by the cleaning roller 4141 and pass through the opposing parts of the photosensitive drum 411 and the cleaning roller 4141.

[0108] The surface potential drop of the photosensitive drum 411 due to the transfer bias is greatly influenced by the type of recording material S and the operating environment of the device body 1. For this reason, it is sometimes preferable to provide a pre-exposure device 417 on the drum cartridge 41. The pre-exposure device 417 is a means of removing surface charge from the photosensitive drum 411. The pre-exposure device 417 reduces the surface potential to near 0V by irradiating the surface area of ​​the photosensitive drum 411 that has passed through the transfer section with light. The pre-exposure device 417 may be a light guide that guides light irradiated from the light source of the device body 1 to the surface of the photosensitive drum 411, or it may be an LED substrate equipped with its own light source. As shown in Figure 6, in this embodiment, the pre-exposure device 417 is configured to incorporate a light guide into a housing shape formed in the drum lower frame 4105. This configuration makes it easier to ensure the distance between the pre-exposure device 417 and the photosensitive drum 411. By employing the pre-exposure device 417, the cleaning roller 4141 can clean the photosensitive drum 411 when its surface potential has sufficiently decreased, thereby improving cleaning efficiency. However, this increases the cost due to the pre-exposure device 417. Therefore, if the surface potential decrease due to the transfer bias is sufficient, the pre-exposure device 417 may be omitted.

[0109] A recovery bias of approximately +600V is applied to the recovery roller 4142. That is, the recovery roller 4142 has a potential difference of approximately +100V compared to the cleaning roller 4141. Therefore, negatively charged residues such as paper dust move to the recovery roller 4142.

[0110] Furthermore, it has been found that recovery efficiency can be increased by creating a peripheral speed difference between the photosensitive drum 411 and the cleaning roller 4141, and between the cleaning roller 4141 and the recovery roller 4142. On the other hand, creating a peripheral speed difference may also increase torque or accelerate damage to the rollers. According to the inventors' research, a peripheral speed difference of about 5% to 20% is preferable.

[0111] The residue collected by the recovery roller 4142 is scraped off the recovery roller 4142 by the scraping member 4144 and collected in the recovery chamber 4145.

[0112] In this way, the cleaning unit 414 can effectively recover paper dust and other materials from the residue remaining on the photosensitive drum 411.

[0113] Furthermore, positively charged toner that is not collected by the cleaning unit 414 may be collected in the toner storage unit 425 by the developing roller 421 after passing through the opposing section between the photosensitive drum 411 and the cleaning roller 4141. In other words, the image forming unit 4 of this embodiment may be a developing and cleaning system in which the developing unit collects and reuses at least a portion of the remaining toner that was not transferred to the recording material S in the transfer unit.

[0114] Next, the support configuration of the cleaning roller 4141 and the recovery roller 4142 will be explained using Figures 9(a) to 10(b).

[0115] As shown in Figure 9(a), an upper opening edge 41043 is formed on the right side of the upper drum frame 4104. A lower opening edge 41051 is formed on the right side of the lower drum frame 4105. When the upper drum frame 4104 and the lower drum frame 4105 are joined together, the upper opening edge 41043 and the lower opening edge 41051 form a single opening (roller opening 410op).

[0116] As shown in Figure 9(b), a cleaning roller shaft 41411 is formed on the cleaning roller 4141. Similarly, a recovery roller shaft 41421 is formed on the recovery roller 4142. As shown in Figure 9(a), when the drum upper frame 4104 and the drum lower frame 4105 are joined and the cleaning roller 4141 and recovery roller 4142 are assembled, the cleaning roller shaft 41411 and recovery roller shaft 41421 protrude to the right through the roller opening 410op.

[0117] As shown in Figure 9(a), there is a gap between the upper edge 41043 and the lower edge 41051 of the opening and the cleaning roller shaft 41411 and the recovery roller shaft 41421. As shown in Figure 9(c), the cleaning bearing 4146 can be installed from the right by inserting it into this gap.

[0118] As shown in Figure 9(d), the cleaning bearing 4146 is a single molded product having a cleaning support portion 41461, a recovery support portion 41462, and a cleaning connecting portion 41463 that connects the cleaning support portion 41461 and the recovery support portion 41462. The cleaning support portion 41461 is a support portion that rotatably supports the cleaning roller shaft 41411. The recovery support portion 41462 is a support portion that rotatably supports the recovery roller shaft 41421. The distance between the axes of the cleaning roller 4141 and the recovery roller 4142 is fixed by the cleaning bearing 4146.

[0119] As shown in Figure 9(e), the drum side cover 4103 has a recovery roller positioning hole 41033 and a cleaning roller guide hole 41034. The recovery roller positioning hole 41033 is the positioning part for the recovery roller 4142. The recovery roller shaft 41421 is rotatably fitted into the recovery roller positioning hole 41033. The recovery roller 4142 is positioned so that the center of the recovery roller shaft 41421 coincides with the center of the recovery roller positioning hole 41033.

[0120] On the other hand, the cleaning roller 4141 is movable along the cleaning roller guide hole 41034 in directions toward and toward the photosensitive drum 411. The cleaning roller guide hole 41034 is a guide portion that restricts the movement trajectory of the cleaning roller 4141. The cleaning roller guide hole 41034 is formed in an arc shape centered on the recovery roller positioning hole 41033. With the cleaning roller shaft 41411 engaged with the cleaning roller guide hole 41034, the cleaning roller 4141 is movable (oscillated) around the recovery roller 4142 along the arc shape of the cleaning roller guide hole 41034. In other words, the cleaning roller 4141 is oscillating along the cleaning roller guide hole 41034 while the axial distance with respect to the recovery roller 4142 is guaranteed by the cleaning bearing 4146. The range of oscillation of the cleaning roller 4141 is restricted by the length of the cleaning roller guide hole 41034.

[0121] Thus, the rotation axis of the recovery roller 4142 is positioned relative to the drum side cover 4103. The axial distance between the cleaning roller 4141 and the recovery roller 4142 is fixed by the cleaning bearing 4146. The cleaning roller 4141 is oscillating around the recovery roller 4142, and the range of oscillation is defined by the drum side cover 4103.

[0122] As shown in Figures 10(a) and 10(b), the drum side cover 4103 is equipped with a wire electrode opening 41031, a grid electrode opening 41032, a recovery roller positioning hole 41033, a cleaning roller guide hole 41034, and a cleaning sliding part 410341. The drum side cover 4103 is also equipped with a recovery power supply member 41035 including a recovery electrode 410353, a cleaning electrode 41036, a drum shaft positioning hole 41037, a cleaning pressure spring 4147, a spring support part 41038, and a cover positioning hole 41039.

[0123] The wire electrode opening 41031 is an opening for exposing the wire electrode 4124 to the right side of the drum side cover 4103. The grid electrode opening 41032 is an opening for exposing the grid electrode 4128 to the right side of the drum side cover 4103. The recovery roller positioning hole 41033 is a hole for rotatably positioning the recovery roller shaft 41421, as described above. The cleaning roller guide hole 41034 is a guide portion that restricts the movement trajectory of the cleaning roller 4141, as described above.

[0124] The cleaning sliding part 410341 is a sliding member that makes the sliding of the cleaning roller shaft 41411 against the cleaning roller guide hole 41034 smoother when the cleaning roller 4141 swings. The cleaning sliding part 410341 is, for example, a cylindrical resin molded product that is press-fitted into the inside of the cleaning roller guide hole 41034.

[0125] The recovery power supply member 41035 is a power supply member electrically connected to the recovery roller 4142. The recovery power supply member 41035 has a recovery electrode 410353. The recovery electrode 410353 is an electrode (contact point with the electrical circuit of the device body 1) for applying a recovery bias to the recovery roller 4142. The cleaning electrode 41036 is an electrode (contact point with the electrical circuit of the device body 1) for applying a cleaning bias to the cleaning roller 4141. The drum shaft positioning hole 41037 is a positioning part that fits with the drum shaft 4111 to position the photosensitive drum 411.

[0126] The cleaning pressure spring 4147 is a pressurizing means for applying pressure to the cleaning roller 4141 toward the photosensitive drum 411. The spring support part 41038 is a support part that supports the cleaning pressure spring 4147. The cover positioning hole 41039 is a positioning hole for assembling the drum side cover 4103 to the drum upper frame 4104 and the drum lower frame 4105.

[0127] The recovery power supply member 41035 is a conductive resin material member having a recovery roller sliding portion 410351, a recovery electrode 410353, and a recovery connecting portion 410352. The recovery roller sliding portion 410351 is a sliding portion that slides with the recovery roller shaft 41421. The recovery connecting portion 410352 is a connecting portion that connects the recovery roller sliding portion 410351 and the recovery electrode 410353. The recovery bias applied to the recovery electrode 410353 is applied to the recovery roller 4142 via the recovery connecting portion 410352 and the recovery roller sliding portion 410351. The recovery power supply member 41035 may be a separate member from the drum side cover 4103, or it may be formed as part of the drum side cover 4103 by a method such as two-color molding.

[0128] By providing the recovery coupling section 410352, the recovery bias can be stably applied to the recovery roller 4142 even when the recovery electrode 410353 is positioned away from the rotation axis of the recovery roller 4142.

[0129] As shown in Figure 10(b), a cover positioning boss 41052 is formed on the drum lower frame 4105. The cover positioning boss 41052 is a positioning part when assembling the drum side cover 4103. A drum shaft positioning hole 41037 is formed on the drum side cover 4103, and the reference position is determined by the engagement of the drum shaft positioning hole 41037 (Figure 10(a)) and the drum shaft 4111. In addition, the orientation of the drum side cover 4103 in the rotational direction around the reference position is determined by the engagement of the cover positioning boss 41052 and the elongated cover positioning hole 41039 (Figure 10(a)). The elongated shape of the cover positioning hole has the effect of absorbing dimensional tolerances and assembly tolerances of the parts.

[0130] The cleaning pressure spring 4147 has a pressurizing portion 41471 for pressurizing the cleaning roller 4141 and a power supply portion 41472 that contacts the cleaning electrode 41036. The cleaning pressure spring 4147 may be a torsion coil spring having a coil portion held by a boss-shaped spring support portion 41038. The pressurizing portion 41471 engages with the cleaning roller shaft 41411 and pressurizes the cleaning roller 4141 in the direction toward the photosensitive drum 411. The power supply portion 41472 is in contact with the cleaning electrode 41036. The cleaning electrode 41036, the cleaning pressure spring 4147, and the cleaning roller shaft 41411 are electrically connected to each other. Therefore, by applying a cleaning bias to the cleaning electrode 41036, a cleaning bias is applied to the cleaning roller 4141 via the cleaning pressure spring 4147.

[0131] The cleaning electrode 41036 is made of a conductive resin material. The cleaning electrode 41036 may be a separate component from the drum side cover 4103, or it may be formed as part of the drum side cover 4103 by a method such as two-color molding.

[0132] By providing the cleaning pressure spring 4147, a cleaning bias can be stably applied to the cleaning roller 4141 even when the cleaning electrode 41036 is positioned away from the rotation axis of the cleaning roller 4141. Note that the cleaning pressure spring 4147 is merely an example of a conductive part that electrically connects the cleaning electrode 41036 and the cleaning roller 4141, and a conductive part may be provided separately from the cleaning pressure spring 4147 as a biasing member that biases the cleaning roller 4141.

[0133] As described above, the cleaning roller 4141 of this embodiment receives a cleaning bias from a cleaning electrode 41036 located on the drum side cover 4103 via a cleaning pressure spring 4147. The recovery roller 4142 of this embodiment receives a recovery bias from a recovery electrode 410353 located on the drum side cover 4103 via a recovery connecting portion 410352 and a recovery roller sliding portion 410351.

[0134] As mentioned above, the drum side cover 4103 has a wire electrode opening 41031 and a grid electrode opening 41032. In other words, the drum side cover 4103 has a covering function that exposes the electrodes to which high-voltage bias is applied and covers the other parts. The covering function of the drum side cover 4103 makes it possible to prevent dirt and foreign matter from entering from the outside, and the tracking phenomenon can be further suppressed.

[0135] [Contacts on the main unit of the device] Next, the image-forming contact section 13, which is a collection of contacts (main body contacts) provided on the main body 1 of the device, will be explained using Figures 11(a) to 12.

[0136] Figures 11(a) to 11(c) show the electrodes provided on the drum cartridge 41 and the developing cartridge 42, and the contact points of the device body 1 for applying bias to each electrode. Figure 11(a) is a perspective view of the right side of the drum cartridge 41 and the developing cartridge 42. Figure 11(b) is a side view showing the right inner wall 120 of the device body 1. The bias generation unit 14 is shown by a dashed line. Figure 11(c) is a top view of the right inner wall 120 of the device body 1. In Figures 11(b) and 11(c), the drum cartridge 41 and the developing cartridge 42 are shown by dashed lines. Figure 12 is a side view showing the arrangement of electrodes on the drum cartridge 41 and the developing cartridge 42 in this embodiment.

[0137] As shown in Figure 11(a), the wire electrode 4124, grid electrode 4128, cleaning electrode 41036, recovery electrode 410353, developing electrode 4261, and supply electrode 4271 are arranged on the right side of the process cartridge 4P. As described above, a high-voltage bias necessary for image formation is applied to each of these electrodes.

[0138] As shown in Figure 11(b), a bias generation unit 14 is located inside the inner wall 120 on the right side of the main body 1 of the apparatus. An image-forming contact unit 13 is located on the surface of the inner wall 120 (the surface facing the process cartridge 4P). The image-forming contact unit 13 includes a main drum contact 131, a main wire contact 132, a main grid contact 133, a main cleaning contact 134, a main recovery contact 135, a main development contact 136, a main supply contact 137, and a main transfer contact 138. The image-forming contact unit 13 is a connecting means that electrically connects the bias generation unit 14 to the electrodes located on the drum cartridge 41 and the development cartridge 42.

[0139] The main drum contact 131 is a contact that contacts the drum shaft 4111 (drum electrode) of the photosensitive drum 411 when the process cartridge 4P is mounted on the main body 1 of the apparatus. By the main drum contact 131 contacting the drum shaft 4111, the conductive substrate of the photosensitive drum 411 can be electrically connected (grounded) to the ground portion of the main body 1 of the apparatus. The ground portion of the main body 1 of the apparatus is, for example, the metal frame of the image forming apparatus 100.

[0140] The main wire contact 132 is a contact that comes into contact with the wire electrode 4124 when the process cartridge 4P is mounted on the main body 1 of the apparatus. When the main wire contact 132 comes into contact with the wire electrode 4124, the bias generation unit 14 and the charged wire 4121 are electrically connected, and a charge bias can be applied from the bias generation unit 14 to the charged wire 4121. In this embodiment, the charge bias is, for example, approximately +4500V.

[0141] The main grid contact 133 is a contact that contacts the grid electrode 4128 when the process cartridge 4P is mounted on the main body 1 of the apparatus. When the main grid contact 133 contacts the grid electrode 4128, the bias generation unit 14 and the grid plate 4126 are electrically connected, and a grid bias can be applied from the bias generation unit 14 to the grid plate 4126. In this embodiment, the grid bias is, for example, approximately +800V.

[0142] The main unit cleaning contact 134 is a contact that comes into contact with the cleaning electrode 41036 when the process cartridge 4P is mounted on the main unit 1 of the apparatus. When the main unit cleaning contact 134 comes into contact with the cleaning electrode 41036, the bias generation unit 14 and the cleaning roller 4141 are electrically connected, and a cleaning bias can be applied from the bias generation unit 14 to the cleaning roller 4141. In this embodiment, the cleaning bias is, for example, approximately +500V.

[0143] The main unit recovery contact 135 is a contact that contacts the recovery electrode 410353 when the process cartridge 4P is mounted on the main unit 1 of the apparatus. When the main unit recovery contact 135 contacts the recovery electrode 410353, the bias generation unit 14 and the recovery roller 4142 are electrically connected, and a recovery bias can be applied from the bias generation unit 14 to the recovery roller 4142. In this embodiment, the recovery bias is, for example, approximately +600V.

[0144] The main body developing contact 136 is a contact that comes into contact with the developing electrode 4261 when the process cartridge 4P is mounted on the main body 1 of the device. When the main body developing contact 136 comes into contact with the developing electrode 4261, the bias generation unit 14 and the developing roller 421 are electrically connected, and a state is created in which a developing bias can be applied from the bias generation unit 14 to the developing roller 421. In this embodiment, the developing bias is, for example, approximately +500V.

[0145] The main supply contact 137 is a contact that contacts the supply electrode 4271 when the process cartridge 4P is mounted on the main body 1 of the device. When the main supply contact 137 contacts the supply electrode 4271, the bias generation unit 14 and the supply roller 423 are electrically connected, and a supply bias can be applied from the bias generation unit 14 to the supply roller 423. In this embodiment, the supply bias is, for example, approximately +650V.

[0146] The main transfer contact 138 is a contact that comes into contact with the transfer electrode 4131 (see also Figure 6) when the process cartridge 4P is mounted on the main body 1 of the apparatus. When the main transfer contact 138 comes into contact with the transfer electrode 4131, the bias generation unit 14 and the transfer roller 413 are electrically connected, and a transfer bias can be applied from the bias generation unit 14 to the transfer roller 413. In this embodiment, the transfer bias is, for example, about -2000V.

[0147] As shown in Figure 11(c), each contact of the image contact section 13, excluding the main body transfer contact 138, is biased by a contact spring 139 toward the process cartridge 4P (downward in the figure). The direction of the biasing force of each contact spring 139 is approximately parallel to the left-right direction (the direction of the rotation axis of the photosensitive drum 411). When the process cartridge 4P is mounted on the main body 1, each contact of the image contact section 13 is pressed against the corresponding electrode of the process cartridge 4P by the biasing force of the contact spring 139.

[0148] On the other hand, as shown in Figures 11(b) and 6, the main body transfer contact 138 has an arm that can be deformed in a direction intersecting the rotation axis of the photosensitive drum 411 (up and down direction in the figure), and the arm contacts the transfer electrode 4131.

[0149] As described above, in this embodiment, the drum cartridge 41 and the developing cartridge 42 are subjected to, for example, seven types of high-voltage biases (wire, grid, cleaning, recovery, developing, supply, and transfer). The main body contacts (132-137) for supplying six of these high-voltage biases, excluding the transfer bias, are concentrated on the right inner wall 120. This configuration simplifies the connection between the bias generation unit 14 and each main body contact. More specifically, one end (left end) of the contact spring 139 is brought into contact with the main body contact (132-137), and the other end (right end) of the contact spring 139 is brought into contact with the electrode for high-voltage bias output mounted on the bias generation unit 14.

[0150] Furthermore, the drum cartridge 41 in this embodiment is provided with a drum shaft 4111 as a drum electrode for electrically grounding the photosensitive drum 411. The main body contact (main body drum contact 131) that contacts the drum shaft 4111 is also located on the right inner wall 120, along with the other main body contacts (132-137). This allows for a simpler connection configuration between the bias generation unit 14 and each main body contact.

[0151] [Suppression of tracking phenomenon] Incidentally, since high-voltage bias is applied to each electrode of the drum cartridge 41 and the developing cartridge 42, and to each contact of the main body 1 of the device, attention must be paid to the tracking phenomenon. The tracking phenomenon is a phenomenon in which tiny discharges occur repeatedly between electrodes due to the influence of dust, dirt, moisture, etc., and a path (track) of carbides connecting the electrodes is formed on the surface of the insulator.

[0152] In particular, the charge bias is high, for example, +4500V. Therefore, it is desirable to suppress the decrease in insulation due to tracking phenomena. In this embodiment, tracking phenomena are suppressed by arranging the process cartridge 4P in a way that allows for a wider distance between electrodes. If the distance between electrodes is wide, it becomes less likely for tracks to form connecting the electrodes.

[0153] As shown in Figure 12, the right side of the drum cartridge 41 is equipped with a wire electrode 4124, a grid electrode 4128, a cleaning electrode 41036, a recovery electrode 410353, and a drum shaft 4111 (drum electrode). The right side of the developing cartridge 42 is equipped with a developing electrode 4261 and a supply electrode 4271.

[0154] To more effectively suppress the tracking phenomenon, it is desirable to increase the distance between electrodes when the potential difference is large. In this embodiment, the high-voltage bias with the largest voltage value is the charging bias applied to the wire electrode 4124 (for example, about +4500V).

[0155] The high-voltage bias with the largest potential difference relative to the charging bias is the transfer bias (e.g., approximately -2000V). In this embodiment, the transfer electrode 4131 is not located on the right side of the drum cartridge 41, so a sufficient distance can be secured. Therefore, tracking phenomena between the wire electrode 4124 and the transfer electrode 4131 are suppressed.

[0156] Since a cleaning bias of, for example, +500V is applied to the cleaning electrode 41036, the potential difference with the charging bias is relatively large. Therefore, it is preferable to position the cleaning electrode 41036 as far away as possible from the wire electrode 4124 to which the charging bias is applied.

[0157] In the viewpoint shown in Figure 12, the imaginary line L1 is defined as a virtual straight line passing through the rotation axis A1 (first rotation axis) of the photosensitive drum 411 and the rotation axis A2 (second rotation axis) of the developing roller 421. According to the inventors' studies, in the viewpoint shown in Figure 12, it is preferable that the wire electrode 4124 and the cleaning electrode 41036 are positioned on opposite sides of the imaginary line L1. This makes it possible to suppress the occurrence of tracking phenomena between the wire electrode 4124 and the cleaning electrode 41036, where the potential difference of the applied high-voltage bias is relatively large.

[0158] In particular, in this embodiment, the rotation axis of the cleaning roller 4141 (the center of the cleaning roller shaft 41411) is located on the same side as the wire electrode 4124 with respect to the virtual line L1. Also, the cleaning roller 4141 itself is located on the same side as the charged wire 4121 with respect to the virtual line L1 (see Figure 6). In this configuration, the cleaning electrode 41036 is deliberately positioned on the opposite side of the wire electrode 4124 with respect to the virtual line L1, and a conductive part is provided to electrically connect the wire electrode 4124 and the cleaning roller shaft 41411. The conductive part is conductive, at least a portion of which is located inside the drum side cover 4103, and extends in a direction intersecting the virtual line L1 (see also Figure 10(a)). The conductive part in this embodiment is a cleaning pressure spring 4147 that contacts both the cleaning electrode 41036 and the cleaning roller shaft 41411 (Figures 10(a) and 10(b)).

[0159] This configuration allows the rotation axis of the cleaning roller 4141 to be located on the same side as the wire electrode 4124 with respect to the virtual line L1, while the cleaning electrode 41036 can be positioned on the opposite side of the wire electrode 4124 with respect to the virtual line L1. Furthermore, since the cleaning pressure spring 4147 (conductive part) is located inside (on the left side) of the drum side cover 4103, which is at least partially made of an insulator (insulating material), it is possible to prevent dust and other debris from coming into contact with the cleaning pressure spring 4147 (conductive part).

[0160] As mentioned above, the cleaning pressure spring 4147 is just one example of a conductive part, and the conductive part may be formed from a different conductive material (such as a metal wire or conductive resin) than the cleaning pressure spring 4147, which acts as a pressurizing means for biasing the cleaning roller 4141.

[0161] Furthermore, the recovery bias applied to the recovery electrode 410353 has a relatively large potential difference from the charging bias. Therefore, it is preferable to position the recovery electrode 410353 as far away from the wire electrode 4124 as possible. Specifically, when viewed from the perspective shown in Figure 12, it is preferable that the wire electrode 4124 and the recovery electrode 410353 are positioned on opposite sides of the virtual line L1. This makes it possible to suppress the occurrence of tracking phenomena between the wire electrode 4124 and the recovery electrode 410353.

[0162] Furthermore, similar to the cleaning roller 4141, the rotation axis of the recovery roller 4142 (the center of the recovery roller shaft 41421) is positioned on the same side as the wire electrode 4124 with respect to the virtual line L1. In this embodiment, the recovery electrode 410353 is deliberately positioned on the opposite side of the wire electrode 4124 with respect to the virtual line L1, and a recovery connecting portion 410352 is provided to electrically connect the wire electrode 4124 and the recovery roller shaft 41421. The recovery connecting portion 410352 is conductive, positioned inside the drum side cover 4103 in the left-right direction, and intersects with the virtual line L1 when viewed in the left-right direction. With this configuration, the rotation axis of the recovery roller 4142 is positioned on the same side as the wire electrode 4124 with respect to the virtual line L1, while the recovery electrode 410353 can be positioned on the opposite side of the wire electrode 4124 with respect to the virtual line L1.

[0163] Incidentally, as a modification, it is conceivable to form the inner surface of the cleaning roller guide hole 41034 with a sliding conductive resin material and use it as a cleaning electrode section for applying a cleaning bias. In this modification, the cleaning electrode 41036 of the above-described embodiment becomes unnecessary, thus reducing the cost of the drum cartridge 41. However, it may be difficult to secure the distance between the wire electrode 4124 and the cleaning electrode section.

[0164] Another modification involves providing the recovery electrode 410353 near the recovery roller shaft 41421. This modification allows for miniaturization of the recovery power supply member 41035, thus reducing costs, but it is difficult to ensure sufficient distance between the wire electrode 4124 and the recovery electrode 410353.

[0165] According to this embodiment, the distance between the wire electrode 4124 and the cleaning electrode 41036, and the distance between the wire electrode 4124 and the recovery electrode 410353 can be ensured.

[0166] Hereinafter, let the distance (shortest distance) between the wire electrode 4124 and the drum shaft 4111 (drum electrode) when viewed from the perspective of FIG. 12 be D1. Let the distance (shortest distance) between the wire electrode 4124 and the cleaning electrode 41036 when viewed from the perspective of FIG. 12 be D2. Let the distance (shortest distance) between the wire electrode 4124 and the recovery electrode 410353 when viewed from the perspective of FIG. 12 be D3. The perspective of FIG. 12 means viewing the process cartridge 4P in the direction of the rotation axis A1 (first rotation axis) of the photosensitive drum 411.

[0167] According to the inventors' investigation, it has been found that if there is a distance of D1 or more between the wire electrode 4124 and the drum shaft 4111, even in the combination of electrodes with a potential difference of 4500V in the applied high-voltage bias, the occurrence of the tracking phenomenon can be more reliably prevented.

[0168] Therefore, it is preferable to arrange the cleaning electrode 41036 so that D1 < D2. In other words, the distance D2 (second distance) between the wire electrode 4124 and the cleaning electrode 41036 is preferably longer than the distance D1 (first distance) between the wire electrode 4124 and the drum shaft 4111 (drum electrode). Thereby, the occurrence of the tracking phenomenon between the wire electrode 4124 and the cleaning electrode 41036 can be more reliably prevented.

[0169] Also, it is preferable to arrange the recovery electrode 410353 so that D1 < D3. In other words, the distance D3 (third distance) between the wire electrode 4124 and the recovery electrode 410353 is preferably longer than the distance D1 (first distance) between the wire electrode 4124 and the drum shaft 4111 (drum electrode). Thereby, the occurrence of the tracking phenomenon between the wire electrode 4124 and the recovery electrode 410353 can be more reliably prevented.

[0170] Since a cleaning bias of the same polarity as the charging bias (e.g., +500 V) is applied to the cleaning electrode 41036, the potential difference between the charging bias and the cleaning bias is smaller than the potential difference between the charging bias and the ground potential (the potential of the drum electrode). Therefore, for example, D2 may be slightly smaller than D1, but by setting the relationship as D1 < D2, the occurrence of the tracking phenomenon can be more reliably prevented. Similarly, since a recovery bias of the same polarity as the charging bias (e.g., +600 V) is applied to the recovery electrode 410353, the potential difference between the charging bias and the recovery bias is smaller than the potential difference between the charging bias and the ground potential (the potential of the drum electrode). Therefore, D3 may be slightly smaller than D1, but by setting the relationship as D1 < D3, the occurrence of the tracking phenomenon can be more reliably prevented.

[0171] Also, both the cleaning bias and the recovery bias have the same polarity as the charging bias, but the recovery bias has a higher voltage. That is, the potential difference between the charging bias and the recovery bias is smaller than the potential difference between the charging bias and the cleaning bias. Therefore, it is preferable that the distance D2 (the second distance) between the wire electrode 4124 and the cleaning electrode 41036 is longer than the distance D3 (the third distance) between the wire electrode 4124 and the recovery electrode 410353. By setting the relationship as D2 > D3, the occurrence of the tracking phenomenon can be more reliably prevented without unnecessarily increasing the size of the drum cartridge 41.

[0172] In the present embodiment, when viewed from the perspective of FIG. 12, the distance from the charging wire 4121 to the wire electrode 4124 is shorter than the distance from the rotation axis of the cleaning roller 4141 to the cleaning electrode 41036. When the distance from the charging wire 4121 to the wire electrode 4124 is shorter, the conductive path to which a higher voltage bias is applied can be shortened. According to the present embodiment, in securing the distance between the wire electrode 4124 and the cleaning electrode 41036, the conductive path from the charging wire 4121 to the wire electrode 4124 can be shortened.

[0173] (Other embodiments) In the embodiment described above, a cartridge equipped with a charging unit 412 which is a scorotron type charger was described, but the charging unit 412 may be, for example, a corotron type charger. When a corotron type charger is used, the configuration of the charging unit 412 and the drum cartridge 41 may be the same as in the embodiment, except that the grid plate 4126 and grid electrode 4128 of the embodiment are omitted.

[0174] Furthermore, in the embodiments described above, examples were given in which roller members (cleaning roller 4141, recovery roller 4142) were used as both the cleaning member and the recovery member. However, the cleaning member and / or recovery member may be, for example, a brush member in which conductive brush fibers are implanted on a rotating shaft.

[0175] Summary of this disclosure This disclosure includes at least the following: (Composition 1) A cartridge comprising a photosensitive drum unit and a developing unit detachably mounted to the photosensitive drum unit, The aforementioned photosensitive drum unit is A photosensitive drum that rotates around the first axis of rotation, A charging wire for charging the surface of the photosensitive drum, A cleaning member for cleaning the surface of the photosensitive drum, A wire electrode is provided, which is arranged on the end face of one end of the photosensitive drum unit in the direction of the first rotation axis and electrically connected to the charging wire, A cleaning electrode is arranged on the end face and electrically connected to the cleaning member, It has, The developing unit has a developing roller that rotates around a second rotation axis and supplies developer to the photosensitive drum, When viewed in the direction of the first rotation axis, the wire electrode and the cleaning electrode are positioned on opposite sides of each other with respect to a virtual straight line passing through the first rotation axis and the second rotation axis. A cartridge characterized by the following features. (Configuration 2) The photosensitive drum unit has drum electrodes arranged on the end face and electrically connected to the photosensitive drum, When the distance between the wire electrode and the drum electrode as viewed in the direction of the first rotation axis is defined as the first distance, and the distance between the wire electrode and the cleaning electrode as viewed in the direction of the first rotation axis is defined as the second distance, The second distance is longer than the first distance. A cartridge according to configuration 1, characterized by the features described above. (Composition 3) The aforementioned photosensitive drum unit is A collection member that comes into contact with the cleaning member and collects paper dust from foreign matter recovered by the cleaning member from the photosensitive drum, A recovery electrode is arranged on the end face and electrically connected to the recovery member, It has, When the distance between the wire electrode and the recovery electrode as viewed in the direction of the first rotation axis is defined as the third distance, The third distance is longer than the first distance. The cartridge according to configuration 2, characterized by the features described above. (Composition 4) The second distance is longer than the third distance. The cartridge according to configuration 3, characterized by the above. (Composition 5) The cleaning member is a cleaning roller that comes into contact with the surface of the photosensitive drum. When viewed in the direction of the first rotation axis, the rotation axis of the cleaning roller is located on the same side as the wire electrode with respect to the virtual straight line. A cartridge according to any one of configurations 1 to 4, characterized by the above. (Composition 6) When viewed in the direction of the first rotation axis, the distance from the charged wire to the wire electrode is shorter than the distance from the rotation axis of the cleaning roller to the cleaning electrode. The cartridge according to configuration 5, characterized by the features described herein. (Composition 7) The photosensitive drum unit includes a cover member that constitutes at least a part of the end face of the photosensitive drum unit, and a conductive part that electrically connects the cleaning electrode and the cleaning roller. At least a portion of the cover member is made of an insulator, The conductive portion is positioned inside the cover member in the direction of the first rotation axis and intersects the virtual straight line when viewed in the direction of the first rotation axis. A cartridge according to configuration 5 or 6, characterized by the above. (Composition 8) The cleaning roller is movable in a direction toward and toward the photosensitive drum. The conductive part is a pressure spring for applying pressure to the cleaning roller toward the photosensitive drum. A cartridge according to configuration 7, characterized by the features described above. (Composition 9) The aforementioned photosensitive drum unit is A grid is placed between the wire electrode and the photosensitive drum, A grid electrode is disposed on the end face and electrically connected to the grid, Having, A cartridge according to any one of configurations 1 to 8, characterized by the above. (Composition 10) The photosensitive drum unit has a means for removing static electricity from the surface of the photosensitive drum. A cartridge according to any one of configurations 1 to 9, characterized by the features described above. (Composition 11) A cartridge described in one of configurations 1 through 10, The device body on which the aforementioned cartridge is detachably mounted, The device comprises a cartridge that forms an image on the recording material when the cartridge is mounted on the main body of the device. An image forming apparatus characterized by the following: (Composition 12) The main body of the aforementioned device is An inner wall facing the end face of the photosensitive drum unit in the direction of the first rotation axis, A plurality of contacts arranged on the inner wall, including a contact that contacts the wire electrode and a contact that contacts the cleaning electrode, A voltage generation unit that generates a voltage to be applied to the cartridge via the plurality of contacts, Having, The image forming apparatus according to configuration 11, characterized by the features described above. [Explanation of symbols]

[0176] 1: Main unit / 4P: Process cartridge (cartridge) / 14: Bias generation unit (voltage generation unit) / 41: Drum cartridge (photosensitive drum unit) / 42: Developer cartridge (developer unit) / 4121: Charged wire / 4124: Wire electrode / 4126: Grid plate (grid) / 4128: Grid electrode / 4141: Cleaning roller (cleaning component) / 4142: Recovery roller (recovery component) / 41036: Cleaning electrode / 410353: Recovery electrode / A1: Rotation axis (first rotation axis) / A2: Rotation axis (second rotation axis) / D1: Distance (first distance) / D2: Distance (second distance) / D3: Distance (third distance) / L1: Imaginary line (imaginary straight line)

Claims

1. A cartridge comprising a photosensitive drum unit and a developing unit detachably mounted to the photosensitive drum unit, The aforementioned photosensitive drum unit is A photosensitive drum that rotates around the first axis of rotation, A charging wire for charging the surface of the photosensitive drum, A cleaning member for cleaning the surface of the photosensitive drum, A wire electrode is positioned on the end face of one end of the photosensitive drum unit in the direction of the first rotation axis and is electrically connected to the charging wire, A cleaning electrode is arranged on the end face and electrically connected to the cleaning member, It has, The developing unit has a developing roller that rotates around a second rotation axis and supplies developer to the photosensitive drum, When viewed in the direction of the first rotation axis, the wire electrode and the cleaning electrode are positioned on opposite sides of each other with respect to a virtual straight line passing through the first rotation axis and the second rotation axis. A cartridge characterized by the following features.

2. The photosensitive drum unit has drum electrodes arranged on the end face and electrically connected to the photosensitive drum, When the distance between the wire electrode and the drum electrode as viewed in the direction of the first rotation axis is defined as the first distance, and the distance between the wire electrode and the cleaning electrode as viewed in the direction of the first rotation axis is defined as the second distance, The second distance is longer than the first distance. The cartridge according to feature 1.

3. The aforementioned photosensitive drum unit is A collection member that comes into contact with the cleaning member and collects paper dust from foreign matter recovered by the cleaning member from the photosensitive drum, A recovery electrode is arranged on the end face and electrically connected to the recovery member, It has, When the distance between the wire electrode and the recovery electrode as viewed in the direction of the first rotation axis is defined as the third distance, The third distance is longer than the first distance. The cartridge according to feature 2.

4. The second distance is longer than the third distance. The cartridge according to feature 3.

5. The cleaning member is a cleaning roller that comes into contact with the surface of the photosensitive drum. When viewed in the direction of the first rotation axis, the rotation axis of the cleaning roller is located on the same side as the wire electrode with respect to the virtual straight line. The cartridge according to feature 1.

6. When viewed in the direction of the first rotation axis, the distance from the charged wire to the wire electrode is shorter than the distance from the rotation axis of the cleaning roller to the cleaning electrode. The cartridge according to feature 5.

7. The photosensitive drum unit includes a cover member that constitutes at least a part of the end face of the photosensitive drum unit, and a conductive part that electrically connects the cleaning electrode and the cleaning roller. At least a portion of the cover member is made of an insulator, The conductive portion is positioned inside the cover member in the direction of the first rotation axis and intersects the virtual straight line when viewed in the direction of the first rotation axis. The cartridge according to feature 5.

8. The cleaning roller is movable in a direction toward and toward the photosensitive drum. The conductive part is a pressure spring for applying pressure to the cleaning roller toward the photosensitive drum. The cartridge according to feature 7.

9. The aforementioned photosensitive drum unit is A grid is placed between the wire electrode and the photosensitive drum, A grid electrode is disposed on the end face and electrically connected to the grid, Having, The cartridge according to feature 1.

10. The photosensitive drum unit has a means for removing static electricity from the surface of the photosensitive drum. The cartridge according to feature 1.

11. A cartridge according to any one of claims 1 to 10, The device body on which the aforementioned cartridge is detachably mounted, The device comprises a cartridge that forms an image on the recording material when the cartridge is mounted on the main body of the device. An image forming apparatus characterized by the following features.

12. The main body of the aforementioned device is In the direction of the first rotation axis, the inner wall facing the end face of the photosensitive drum unit, A plurality of contacts arranged on the inner wall, including a contact that contacts the wire electrode and a contact that contacts the cleaning electrode, A voltage generation unit that generates a voltage to be applied to the cartridge via the plurality of contacts, Having, The image forming apparatus according to feature 11.

Images