Charging system, and image forming system

Abstract

To reduce formation of a layer of attachment on a surface of a charging member, compared with a case where a removing member rotating following a charging member is always in contact with the charging member.SOLUTION: A charging system comprises: a charging member that rotates following a rotating image holding body and charges the image holding body with static electricity; a removing member that rotates following the rotating charging member while arranged at a contact position in contact with the charging member, and removes an attachment attached to the charging member; a moving member that moves the removing member to the contact position and a separated position separated from the charging member; and at least one processor. The processor controls the moving member to move, at a predetermined time, the removing member arranged at the separated position to the contact position, and causes the removing member to remove the attachment attached to the charging member for a removal time.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to a charging system and an image forming system. [Background technology]

[0002] The image forming apparatus described in Patent Document 1 has an image carrier on which an image is formed, a charging roll that charges the image carrier, a first support means that supports the charging roll, a cleaning member that cleans the charging roll, a second support means that supports the first support means, and a moving means that moves the second support means, and the second support means supports the first support means so that movement of the second support means moves the charging roll to a printing position where it contacts the surface of the image carrier and a retracted position where it does not contact the surface of the image carrier. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2007-193207 A Summary of the Invention [Problem to be solved by the invention]

[0004] There is a removal member that removes the deposits that have adhered to the rotating charged member. This removal member is always in contact with the charged member and rotates in accordance with the rotation of the charged member to remove the deposits that have adhered to the charged member.

[0005] However, the deposits remaining on the charged member that were not removed by the removing member are pressed against the charged member by the removing member that rotates in contact with the charged member, which may result in a layer of deposits being formed on the charged member.

[0006] An object of the present disclosure is to suppress formation of a layer of deposits on the charged member, compared to a case in which a removing member that rotates following the charging member is in constant contact with the charged member. [Means for solving the problem]

[0007] A charging system according to a first aspect of the present disclosure includes a charging member that rotates in conjunction with a rotating image carrier and charges the image carrier, a removal member that rotates in conjunction with the rotating charging member while being positioned at a contact position in contact with the charging member and removes adhesions adhered to the charged member, a moving member that moves the removal member to a separation position separated from the charged member and the contact position, and at least one processor, wherein the processor controls the moving member to move the removal member that is positioned at the separation position to the contact position at a predetermined time, and causes the removal member to remove adhesions adhered to the charged member for a removal time.

[0008] A charging system according to a second aspect of the present disclosure is characterized in that, in the charging system described in the first aspect, after the number of images formed on the image carrier since the previous removal of adhesion reaches a predetermined number, the processor moves the removal member arranged at the separated position to the contact position and causes the removal member to remove adhesion adhered to the charging member for the removal time.

[0009] A charging system according to a third aspect of the present disclosure is characterized in that, in the charging system described in the second aspect, the processor moves the removal member disposed at the separated position to the contact position after the number of images since the previous removal of adhesion reaches a predetermined number and during non-image formation.

[0010] A charging system according to a fourth aspect of the present disclosure is characterized in that, in the charging system described in the first aspect, after the number of cycles of the image carrier since the previous removal of adhesion reaches a predetermined number, the processor moves the removal member arranged at the separated position to the contact position and causes the removal member to remove adhesion adhered to the charging member for the removal time.

[0011] A charging system according to a fifth aspect of the present disclosure is the charging system described in the fourth aspect, characterized in that the processor moves the removal member disposed at the separated position to the contact position after the number of cycles since the previous removal of adhesion reaches a predetermined number and during non-image formation.

[0012] A charging system according to a sixth aspect of the present disclosure is the charging system described in the first aspect, further comprising a detection unit that detects electrical resistance between the charging member and the image carrier, and the processor is characterized in that after the electrical resistance has increased by a predetermined amount since the previous removal of adhesion, the processor moves the removal member disposed at the separated position to the contact position and causes the removal member to remove the adhesion adhered to the charging member for the removal time.

[0013] A charging system according to a seventh aspect of the present disclosure is the charging system described in the sixth aspect, characterized in that the processor moves the removal member disposed at the separated position to the contact position after an increase in the electrical resistance since the previous removal of adhesion reaches a predetermined threshold and during non-image formation.

[0014] A charging system according to an eighth aspect of the present disclosure is the charging system described in the sixth aspect, characterized in that the processor derives the difference in electrical resistance before and after removal of adhesions, and when the difference in electrical resistance is small, the next removal time is made longer than when the difference in electrical resistance is large.

[0015] An image forming system according to a ninth aspect of the present disclosure is characterized by comprising: a charging system as defined in any one of claims 1 to 8; an image carrier that is charged by the charging system and on which an image is formed; and a transfer device that transfers the image formed on the image carrier to a recording medium. Effect of the Invention

[0016] According to the charging system of the first aspect of the present disclosure, the formation of a layer of adhesion on the charged member can be suppressed compared to a case in which the removal member, which rotates in conjunction with the charged member, is constantly in contact with the charged member.

[0017] According to the charging system of the second aspect of the present disclosure, formation of a layer of attached matter on the charging member can be suppressed, compared to a case in which attached matter is removed at predetermined time intervals.

[0018] According to the charging system of the third aspect of the present disclosure, degradation of image quality can be suppressed compared to a case in which the removal member disposed at the separate position is moved to the contact position during image formation.

[0019] According to the charging system of the fourth aspect of the present disclosure, formation of a layer of adhering matter on the charging member can be effectively suppressed, compared to a case in which the adhering matter is removed at predetermined time intervals.

[0020] According to the charging system of the fifth aspect of the present disclosure, degradation of image quality can be suppressed compared to a case in which the removal member disposed at the separate position is moved to the contact position during image formation.

[0021] According to the charging system of the sixth aspect of the present disclosure, formation of a layer of adhering matter on the charging member can be effectively suppressed, compared to a case in which the adhering matter is removed at predetermined time intervals.

[0022] According to the charging system of the seventh aspect of the present disclosure, degradation of image quality can be suppressed compared to a case in which the removal member disposed at the separate position is moved to the contact position during image formation.

[0023] According to the charging system of the eighth aspect of the present disclosure, the deposits adhering to the charging member can be removed more effectively than when the removal time is always the same.

[0024] According to the image forming system of the ninth aspect of the present disclosure, density unevenness in the output image can be suppressed, compared to a case including a charging system in which the removing member is constantly in contact with the charging member. [Brief description of the drawings]

[0025] [Figure 1] 1 is a schematic configuration diagram showing an image forming apparatus according to a first embodiment of the present disclosure. [Diagram 2] 1 is a configuration diagram showing an image forming unit and a transfer device provided in an image forming apparatus according to a first embodiment of the present disclosure. [Diagram 3] FIG. 2 is a configuration diagram showing a charging device according to the first embodiment of the present disclosure. [Figure 4] 4 is a perspective view showing an end portion of a removal member provided in the charging device according to the first embodiment of the present disclosure. FIG. [Diagram 5] 3A and 3B are diagrams showing the charging device according to the first embodiment of the present disclosure, illustrating a state in which the removal member is disposed at the contact position and a state in which the removal member is disposed at the separate position. [Figure 6] 3A and 3B are diagrams showing a hardware configuration and a functional configuration of a control unit provided in a charging device according to a first embodiment of the present disclosure. [Figure 7] FIG. 4 is a flow diagram showing a removal process for removing deposits adhered to the charging roll of the charging device according to the first embodiment of the present disclosure. [Figure 8] 1 is a graph showing evaluation results of an example according to the first embodiment of the present disclosure and a comparative example. [Figure 9] 1 is a drawing showing, in the form of a table, evaluation results of examples according to the first embodiment of the present disclosure and comparative examples. [Figure 10] 13A and 13B are diagrams showing a hardware configuration and a functional configuration of a control unit provided in a charging device according to a second embodiment of the present disclosure. [Figure 11] FIG. 11 is a flow diagram showing a removal process for removing deposits that have adhered to a charging roll of a charging device according to a second embodiment of the present disclosure. [Figure 12]FIG. 11 is a configuration diagram showing a charging device according to a third embodiment of the present disclosure. [Figure 13] 13A and 13B are diagrams showing a hardware configuration and a functional configuration of a control unit provided in a charging device according to a third embodiment of the present disclosure. [Figure 14] FIG. 11 is a flow diagram showing a removal process for removing deposits that have adhered to a charging roll of a charging device according to a third embodiment of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0026] First Embodiment An example of a charging device and an image forming apparatus according to a first embodiment of the present disclosure will be described with reference to Fig. 1 to Fig. 9. Note that, in the drawings, arrow H indicates the up-down direction (vertical direction) of the apparatus, arrow W indicates the width direction (horizontal direction) of the apparatus, and arrow D indicates the depth direction (horizontal direction) of the apparatus.

[0027] (Image forming apparatus 10) 1, the image forming apparatus 10 includes a first housing 12, a second housing 14, an image forming section 16, a medium conveying section 50, a post-processing section 60, and a control section 68. The control section 68 controls each section constituting the image forming apparatus 10 (each section constituting the image forming section 16, etc.). The image forming apparatus 10 is an example of an image forming system. The first housing 12 and the second housing 14 are arranged side by side in the width direction of the device and are connected by a connecting mechanism 44.

[0028] [Image forming unit 16] As shown in Fig. 1, the image forming unit 16 is disposed inside the first housing 12, and as shown in Fig. 2, the image forming unit 16 includes a toner image forming unit 20 that forms a toner image, and a transfer device 30 that transfers the image formed by the toner image forming unit 20 onto a sheet member P serving as a recording medium. The image forming unit 16 further includes a fixing device 40 that fixes the toner image transferred onto the sheet member P onto the sheet member P. The image forming unit 16 forms an image on the sheet member P by an electrophotographic method.

[0029] -Toner image forming unit 20- As shown in FIG. 2, the toner image forming unit 20 includes an image carrier 21, a charging device 22, an exposure device 23, and a developing device 24. A plurality of toner image forming units 20 are provided to form toner images for each color. In this embodiment, a total of four toner image forming units 20 of yellow (Y), magenta (M), cyan (C), and black (K) are provided. The toner image forming units 20 of each color have the same structure, and the toner image forming units 20 of each color are arranged in the order of yellow (Y), magenta (M), cyan (C), and black (K) from the upstream side in the rotation direction of the transfer belt 31 provided in the transfer device 30. The image carrier 21 of each color is in contact with the transfer belt 31. The toner image forming units 20 of each color are arranged in the device width direction. When it is not necessary to distinguish between Y, M, C, and K, the toner image forming units 20 of each color may be omitted.

[0030] The image carrier 21 is formed in a cylindrical shape and is rotated around its own axis by a driving means (not shown). A photosensitive layer exhibiting a negative charging polarity is formed on the outer peripheral surface of the image carrier 21, for example. An overcoat layer may be formed on the outer peripheral surface of the image carrier 21.

[0031] The charging device 22 is in contact with the outer peripheral surface (photosensitive layer) of the image carrier 21, rotates while being driven by the rotating image carrier 21, and includes a charging roll 70 as an example of a charging member that negatively charges the outer peripheral surface of the image carrier 21. The charging device 22 is an example of a charging system. The charging device 22 will be described in detail later.

[0032] The exposure device 23 is configured to form an electrostatic latent image on the outer peripheral surface of the image holder 21. Specifically, the exposure device 23 is configured to irradiate the outer peripheral surface of the image holder 21, which has been charged by the charging device 22, with exposure light L modulated according to image data. Then, an electrostatic latent image is formed on the outer peripheral surface of the image holder 21 by the irradiation of the exposure light L.

[0033] The developing device 24 develops an electrostatic latent image formed on the outer peripheral surface of the image carrier 21 into a toner image using developer G containing toner T (an example of powder) and carrier CA, thereby forming a toner image on the outer peripheral surface of the image carrier 21. A toner cartridge 39 for refilling the developing device 24 with toner T is connected to the developing device 24 via a conveying path (not shown). The toner cartridges 39 for each color are arranged side by side in the device width direction above the exposure device 23, and are individually detachable (replaceable) from the first housing 12.

[0034] The transfer device 30 includes an endless transfer belt 31 onto which the toner images of the image carriers 21 of each color are transferred, and the transfer belt 31 is wound around a plurality of rolls 32 to determine its position. In this embodiment, the transfer belt 31 is oriented in the shape of an inverted obtuse triangle that is long in the device width direction when viewed from the front side.

[0035] Of the multiple rolls 32, roll 32d functions as a drive roll that rotates transfer belt 31 in the direction of arrow A. Also, of the multiple rolls 32, roll 32t functions as a tension applying roll that applies tension to transfer belt 31. Of the multiple rolls 32, roll 32b functions as an opposing roll to a secondary transfer roll 34 described later.

[0036] Furthermore, primary transfer rolls 33 that transfer the toner images formed on the outer circumferential surfaces of the image carriers 21 onto the transfer belt 31 are disposed on the opposite sides of the image carriers 21 of the respective colors.

[0037] Furthermore, a secondary transfer roll 34 that transfers the toner image transferred to the transfer belt 31 onto a sheet material P is in contact with the apex of the lower end side of the transfer belt 31, which forms an obtuse angle, and a transfer nip NT is formed between the transfer belt 31 and the secondary transfer roll 34.

[0038] The fixing device 40 is configured to fix the toner image onto the sheet member P onto which the toner image has been transferred by the transfer device 30. In this embodiment, the fixing device 40 is configured to fix the toner image onto the sheet member P by applying heat and pressure to the toner image in the fixing nip NF.

[0039] [Medium transport unit 50] 1, the medium transport unit 50 includes a medium supply unit 52 that supplies the sheet material P to the image forming unit 16, and a medium discharge unit 54 that discharges the sheet material P on which an image has been formed. Furthermore, the medium transport unit 50 includes a medium return unit 58 that is used when forming images on both sides of the sheet material P, and an intermediate transport unit 59 that transports the sheet material P from the transfer device 30 to the fixing device 40.

[0040] The medium supply unit 52 is adapted to supply the sheet material P one by one in accordance with the transfer timing to the transfer nip NT of the image forming unit 16. In response to this, the medium discharge unit 54 is adapted to discharge the sheet material P on which the toner image has been fixed by the fixing device 40 to the outside of the device. Furthermore, the medium return unit 58 is adapted to return the sheet material P to the image forming unit 16 (medium supply unit 52) ​​by turning it over when forming an image on the other side of the sheet material P on one side of which the toner image has been fixed.

[0041] [Post-processing section 60] As shown in FIG. 1, the post-processing unit 60 is disposed inside the second housing 14, and is configured to include a medium cooling unit 62 that cools the sheet material P on which an image is formed, a correction device 64 that corrects the curvature of the sheet material P, and an image inspection unit 66 that inspects the image.

[0042] The various components constituting the post-processing section 60 are arranged in the medium discharge section 54 of the medium conveying section 50, and the medium cooling section 62, the correction device 64 and the image inspection section 66 are arranged in this order from the upstream side in the discharge direction of the sheet material P.

[0043] (Function of Image Forming Apparatus 10) Next, an overview of the image forming process on the sheet member P by the image forming apparatus 10 and the post-processing process will be described.

[0044] When an image is formed on the sheet member P, the image carrier 21 and a developing roll (reference numeral omitted) provided in the developing device 24 are rotated, and the transfer belt 31 is rotated. Furthermore, the pressure roll 42 provided in the fixing device 40 is rotated, and the fixing belt (reference numeral omitted) is rotated.

[0045] The image carriers 21 of each color are charged by the charging devices 22 while rotating. The exposure devices 23 of each color emit the exposure light L of the corresponding color according to the image data, and expose the charged image carriers 21 of each color. An electrostatic latent image is formed on the outer peripheral surface of the image carriers 21 of each color. The electrostatic latent image formed on the image carriers 21 of each color is developed into a toner image by the developer G supplied from the developing device 24. As a result, a toner image of the corresponding color among yellow (Y), magenta (M), cyan (C), and black (K) is formed on the image carriers 21 of each color.

[0046] Furthermore, the toner images of each color formed on the image carriers 21 of each color are sequentially transferred to the rotating transfer belt 31 by the primary transfer rolls 33 of each color. As a result, a toner image in which toner images of four colors are superimposed is formed on the transfer belt 31. This toner image is transported to the transfer nip NT by the rotation of the transfer belt 31. At this transfer nip NT, the toner image is transferred from the transfer belt 31 to the sheet member P to which it is transported.

[0047] The sheet member P onto which the toner image has been transferred is transported by the intermediate transport section 59 from the transfer nip NT of the transfer device 30 to the fixing nip NF of the fixing device 40. The fixing device 40 applies heat and pressure (fixing energy) to the sheet member P passing through the fixing nip NF. As a result, the toner image transferred to the sheet member P is fixed to the sheet member P.

[0048] The sheet material P heated by the fixing device 40 is first cooled in the medium cooling section 62. Next, the curvature of the sheet material P is straightened by the straightening device 64. Furthermore, the toner image fixed to the sheet material P is inspected by the image inspection section 66 to detect the presence or absence and the degree of toner density defects, image defects, image position defects, etc. Then, the sheet material P is discharged to the outside of the second housing 14 by the medium discharge section 54.

[0049] On the other hand, when an image is to be formed on the non-image side (reverse side) of the sheet material P on which no image is formed (in the case of double-sided printing), the transport path of the sheet material P that has passed through the image inspection unit 66 is switched from the medium discharge unit 54 to the medium return unit 58. As a result, the sheet material P is turned over and sent to the medium supply unit 52. An image is formed (fixed) on the reverse side of this sheet material P in a process similar to that described above, and the sheet material P is discharged to the outside of the second housing 14 by the medium discharge unit 54.

[0050] (Main part configuration) Next, the charging device 22 will be described.

[0051] 3, the charging device 22 is disposed above the image carrier 21, and includes a charging roll 70 that negatively charges the outer peripheral surface of the image carrier 21, and a removing member 72 that removes deposits from the surface of the charging roll 70. The charging device 22 further includes a moving member 80 that rotatably supports the removing member 72 and moves the removing member 72 between a separated position where it is separated from the charging roll 70 and a contact position where it is in contact with the charging roll 70, and a control unit 90 (see FIG. 6) that controls each unit.

[0052] [Charging roll 70] 3, the charging roll 70 includes a cylindrical shaft member 70a extending in the device depth direction, and a cylindrical roll portion 70b through which the shaft member 70a penetrates. The charging roll 70 is an example of a charging member. The roll portion 70 b contacts the outer peripheral surface of the image carrier 21 from above the image carrier 21 .

[0053] In this configuration, the charging roll 70 rotates in accordance with the rotation of the image carrier 21. A voltage is applied from a power source to the charging roll 70, which rotates in accordance with the rotation of the image carrier 21, so that the charging roll 70 charges the outer circumferential surface of the image carrier 21.

[0054] [Removal member 72] As shown in FIG. 3, the removal member 72 includes a cylindrical core material 74 extending in the device depth direction, and a removal material 76 wound in a spiral shape around the outer circumferential surface of the core material 74.

[0055] The removal material 76 contacts the outer circumferential surface of the charging roll 70 from above the charging roll 70. Furthermore, the core material 74 of the removal member 72 is rotatably supported by a pair of support members 82 that are disposed at both ends of the removal member 72. In other words, the core material 74 is supported by the support members 82 to be rotatable around the axis of the core material 74.

[0056] The core material 74 is, for example, molded from a resin material (such as polyacetal resin). The removal material 76 is, for example, molded by foaming urethane resin, and has a rectangular cross section in a free state when not wrapped around the outer circumferential surface of the core material 74. The removal material 76 is fixed to the outer circumferential surface of the core material 74 by using double-sided tape (not shown).

[0057] As shown in Fig. 4, holes 78 extending in the axial direction of the core material 74 are formed at both ends of the core material 74 (only one side is shown in Fig. 4). Then, both ends of the removal material 76 are compressed in the thickness direction and fitted into the holes 108.

[0058] In this configuration, the removing material 76 comes into contact with the roll portion 70b of the rotating charging roll 70, and the removing member 72 rotates in response, whereby the removing material 76 scrapes off and removes the deposits adhering to the roll portion 70b.

[0059] [Moving member 80] 3, the moving members 80 are disposed on both ends of the removing member 72. Each moving member 80 includes a support member 82 that rotatably supports the removing member 72, a solenoid 84 that moves the support member 82 in a direction toward or away from the charging roll 70, and a biasing member 86 that biases the removing member 72 toward the charging roll 70.

[0060] The support member 82 has a rectangular parallelepiped shape and supports the core 74 of the removal member 72 via a bearing. The solenoid 84 is disposed above the support member 82. The biasing member 86 is a compression coil spring that extends in the vertical direction, and is disposed between the support member 82 and the solenoid 84.

[0061] In this configuration, when the solenoid 84 is in a non-energized state, the moving member 80 moves the removing material 76 to a separated position away from the charged roll 70, as shown in Fig. 5(B). On the other hand, when the solenoid 84 is energized, the moving member 80 moves the removing material 76 to a contact position in contact with the charged roll 70, as shown in Fig. 5(A). Then, the removing member 72 that has moved to the contact position rotates following the rotation of the charged roll 70, and scrapes off and removes the deposits adhering to the charged roll 70.

[0062] [Control unit 90] -Hardware configuration of the control unit 90- 6A, the control unit 90 has a CPU (Central Processing Unit) 91, a ROM (Read Only Memory) 92, a RAM (Random Access Memory) 93, a storage 94, and a communication interface (I / F) 95. Each component is connected to each other so as to be able to communicate with each other via a bus 99. The CPU 91 is an example of a processor.

[0063] The CPU 91 is a central processing unit that executes various programs and controls each part. That is, the CPU 91 reads a program from the ROM 92 or the storage 94, and executes the program using the RAM 93 as a working area. The CPU 91 controls each component and performs various calculation processes according to the program stored in the ROM 92 or the storage 94.

[0064] In this embodiment, for example, the ROM 92 or the storage 94 stores a drive program for energizing the solenoid 84 based on print job information.

[0065] The RAM 93 temporarily stores programs or data as a working area. The storage 94 is configured with a hard disk drive (HDD) or a solid state drive (SSD), and stores various programs including an operating system, and various data.

[0066] The communication interface 95 is an interface for communicating with the solenoid 84 and the like, and uses standards such as Ethernet (registered trademark), FDDI, and Wi-Fi (registered trademark), for example.

[0067] When executing the above operating program, the control unit 90 realizes various functions using the above hardware resources. Next, a functional configuration of the control unit 90 that realizes various functions will be described.

[0068] -Functional configuration of the control unit 90- 6(B), the control unit 90 has a receiving unit 96, a determining unit 97, and an operating unit 98. Each functional configuration is realized by the CPU 91 reading and executing a driving program stored in the ROM 92 or the storage 94. The control unit 90 will be described in detail together with the operation described later.

[0069] (Function of main components) Next, the removal process for removing the deposits adhered to the charging roll 70 using the removing member 72 will be described with reference to the flow diagram of Fig. 7. In the initial state before entering the removal process, the removing member 72 is disposed at the separated position.

[0070] When the receiving unit 96 of the control unit 90 receives from the control unit 68 of the image forming device 10 information about a print job to be executed by the image forming device 10, in step S100, the judgment unit 97 of the control unit 90 judges, based on the print job information, whether the number of images since the previous removal has reached a threshold value.

[0071] Specifically, the determination unit 97 determines whether or not the cumulative number of images will reach a threshold value when the removal member 72 moves to the contact position to remove the deposits from the charging roll 70 and then executes the received print job. In the present embodiment, as an example, the threshold value for the number of images is set to 50,000 sheets. In other words, the determination unit 97 determines whether or not the cumulative number of images will reach 50,000 sheets when the removal member 72 moves to the contact position to remove the deposits from the charging roll 70 and then executes the received print job. If the number of images reaches the threshold value, the process proceeds to step S200, and if the number of images does not reach the threshold value, the process of step S100 is performed again.

[0072] In step S200, the receiving unit 96 receives operation information of the image forming apparatus 10 from the control unit 68 of the image forming apparatus 10, and the determination unit 97 determines whether the print job has ended. When the print job has ended, the process proceeds to step S300, and when the print job has not ended, the process of step S200 is performed again.

[0073] In step S300, the operating unit 98 energizes the solenoid 84 and moves the removal member 72 from the separated position (see FIG. 5B) to the contact position (see FIG. 5A) for a predetermined time. The removal member 72 that has moved to the contact position rotates following the rotating charging roll 70 and scrapes off and removes the deposits that have adhered to the charging roll 70. In this embodiment, as an example, the time that the removal member 72 is in the contact position is set to 120 [sec]. In other words, the removal time for removing the deposits is set to 120 [sec]. When the removal member 72 reaches 120 [sec] after moving to the contact position, the operating unit 98 de-energizes the solenoid 84 and moves the removal member 72 from the contact position (see FIG. 5A) to the separated position (see FIG. 5B). When the removal member 72 moves to the separated position, the process proceeds to step S400.

[0074] In step S400, the receiving unit 96 receives information on the presence or absence of a print job to be executed by the image forming apparatus 10 from the control unit 68 of the image forming apparatus 10, and if there is a print job, the process returns to step S100 again to execute the above-mentioned process. On the other hand, if there is no print job, the example operation is terminated.

[0075] - Actual machine testing - Here, the following actual machine test was carried out using a DocuCentreVI C7771 manufactured by Fujifilm Business Innovation Co., Ltd. The evaluation conditions, evaluation items, and evaluation results of the actual machine test are explained below.

[0076] (1) Example 1 Evaluation conditions An image with an image density (area coverage) of 80% was printed in black on 250,000 sheets of A4 size paper.

[0077] In Example 1, the threshold value of the number of images was set to 50,000 sheets (50 kPV). That is, the removal member 72 was moved to the contact position every 50,000 sheets (50 kPV). The removal time was set to 120 [sec]. That is, the contact state of the removal member 72 was maintained for 120 [sec].

[0078] Evaluation items The volume resistivity of the charging roll 70 was measured every 50,000 sheets (50 kPV). The target value of the volume resistivity of the charging roll 70 after printing 250,000 sheets is less than 10.5 [Ωcm].

[0079] Regarding the volume resistivity, a sheet-shaped measurement sample is taken from the measurement object, and the measurement sample is measured in accordance with JIS K 6911 (1995) using a measurement jig (R12702A / B resistivity chamber: manufactured by Advantest Corporation) and a high resistance meter (R8340A digital high resistance / micro ammeter: manufactured by Advantest Corporation) to apply a voltage adjusted to an electric field (applied voltage / composition sheet thickness) of 1000 V / cm for 30 seconds, and then the volume resistivity is calculated from the flowing current value using the following formula.

[0080] Volume resistivity (Ωcm) = (19.63 x applied voltage (V)) / (current value (A) x measured sample thickness (cm))

[0081] Furthermore, after printing 250,000 sheets (250 kPV), the change in volume resistivity of the charging roll 70 was derived. The target value of the change in volume resistivity after printing 250,000 sheets (250 kPV) is less than 2.0 [Ωcm].

[0082] In addition, after printing 250,000 sheets (250 kPV), the thickness of the deposits (discharge products, external additives, etc.) accumulated on the charging roll 70 was measured by SEM observation. The target value for the thickness of the deposit layer after printing 250,000 sheets (250 kPV) is less than 2.0 μm.

[0083] Furthermore, the grade of density unevenness in the output image caused by contamination of the charging roll 70 was evaluated on a four-level scale: O, △, ×, and XX. The grade of density unevenness was evaluated by visually inspecting the output image, and a level that was acceptable for the product was rated as "O", while levels that were unacceptable for the product were rated as "△", "×", and "XX", in order of decreasing degree of unacceptability.

[0084] Evaluation results The change in volume resistivity of the charging roll 70 in Example 1 is shown in the graph shown in Fig. 8. The horizontal axis of this graph is the number of prints (number of images), and the vertical axis is the volume resistivity. The solid line in the graph indicates the change in volume resistivity of the charging roll 70 in Example 1. The dashed line in the graph indicates the volume resistivity from after the previous deposit removal process to the volume resistivity before the next deposit removal process in Example 1, so that the change in volume resistivity before and after deposit removal can be seen.

[0085] As can be seen from this graph, in Example 1, the volume resistivity of the charging roll 70 after printing 250,000 sheets (250 kPV) was less than 10.5 [Ωcm], which meets the target.

[0086] Furthermore, in Example 1, the change in volume resistivity of the charging roll 70 after printing 250,000 sheets (250 kPV) was 0.1 [Ωcm], as shown in the table in FIG. 9, which meets the target.

[0087] In Example 1, the thickness of the layer of deposits on the charging roll 70 after printing 250,000 sheets (250 kPV) is 0.0 μm, as shown in the table in Fig. 9. In this way, the thickness of the layer of deposits is less than 2.0 μm, which meets the target.

[0088] In addition, in Example 1, the grade of density unevenness of the output image after printing 250,000 sheets (250 kPV) was "Good" as shown in the table in Fig. 9. In other words, the density unevenness is at an acceptable level for commercial products.

[0089] (2) Example 2 Evaluation conditions In Example 2, the threshold value of the number of images was set to 5,000 sheets (5 kPV). That is, the removal member 72 was moved to the contact position every 5,000 sheets (5 kPV). The removal time was set to 60 [sec]. That is, the contact state of the removal member 72 was maintained for 60 [sec]. The other conditions were the same as those in Example 1.

[0090] Evaluation items The evaluation items are the same as those in the first embodiment.

[0091] Evaluation results The change in volume resistivity of the charging roll 70 of Example 2 is shown in the graph shown in Fig. 8. Specifically, the dashed dotted line in the graph indicates the change in volume resistivity of the charging roll 70 of Example 2. As can be seen from this graph, in Example 2, the volume resistivity of the charging roll 70 after printing 250,000 sheets (250 kPV) is less than 10.5 [Ωcm], which meets the target.

[0092] Furthermore, in Example 2, the change in volume resistivity of the charging roll 70 after printing 250,000 sheets (250 kPV) was 0.5 [Ωcm], as shown in the table in FIG. 9, which meets the target.

[0093] In Example 2, the thickness of the layer of deposits on the charging roll 70 after printing 250,000 sheets (250 kPV) is 0.5 μm, as shown in the table in Fig. 9. In this way, the thickness of the layer of deposits is less than 2.0 μm, which meets the target.

[0094] In Example 2, the grade of density unevenness of the output image after printing 250,000 sheets (250 kPV) was "Good" as shown in the table in Fig. 9. In other words, the density unevenness is at an acceptable level for commercial products.

[0095] (3) Example 3 Evaluation conditions In Example 3, the threshold value of the number of images was set to 100 sheets (100 PV). That is, the removal member 72 was moved to the contact position every 100 sheets (100 PV). The removal time was set to 10 seconds. That is, the contact state of the removal member 72 was maintained for 10 seconds. Other conditions were the same as those in Example 1.

[0096] Evaluation items The evaluation items are the same as those in the first embodiment.

[0097] Evaluation results The change in volume resistivity of the charging roll 70 of Example 3 is shown in the graph shown in Fig. 8. Specifically, the two-dot chain line in the graph indicates the change in volume resistivity of the charging roll 70 of Example 3. As can be seen from this graph, in Example 3, the volume resistivity of the charging roll 70 after printing 250,000 sheets (250 kPV) is less than 10.5 [Ωcm], which meets the target.

[0098] Furthermore, in Example 3, the change in volume resistivity of the charging roll 70 after printing 250,000 sheets (250 kPV) was 1.7 [Ωcm], as shown in the table in FIG. 9, which meets the target.

[0099] In Example 3, the thickness of the layer of deposits on the charging roll 70 after printing 250,000 sheets (250 kPV) is 1.0 μm, as shown in the table in Fig. 9. In this way, the thickness of the layer of deposits is less than 2.0 μm, which meets the target.

[0100] In Example 3, the grade of density unevenness of the output image after printing 250,000 sheets (250 kPV) was "Good" as shown in the table in Fig. 9. In other words, the density unevenness is at an acceptable level for commercial products.

[0101] (4) Comparative Example Evaluation conditions In the comparative example, the removing member 72 was moved to the contact position and maintained in that state. In other words, the removing member 72 was always in contact with the charging roll 70.

[0102] Evaluation items The evaluation items are the same as those in the first embodiment.

[0103] Evaluation results The change in volume resistivity of the charging roll 70 of the comparative example is shown in the graph in Fig. 8. Specifically, the dotted line in the graph indicates the change in volume resistivity of the charging roll 70 of the comparative example. As can be seen from this graph, in the comparative example, the volume resistivity of the charging roll 70 after printing 250,000 sheets (250 kPV) is 10.5 Ωcm or more, which does not meet the target.

[0104] Furthermore, in the comparative example, the change in volume resistivity of the charging roll 70 after printing 250,000 sheets (250 kPV) was 2.6 [Ωcm], as shown in the table in FIG. 9, which does not meet the target.

[0105] In the comparative example, the thickness of the layer of deposits on the charging roll 70 after printing 250,000 sheets (250 kPV) is 2.0 μm, as shown in the table in Fig. 9. Thus, the thickness of the layer of deposits is 2.0 μm or more, which does not meet the target.

[0106] In the comparative example, the grade of uneven density of the output image after printing 250,000 sheets (250 kPV) was "X" as shown in the table in Fig. 9. In other words, the uneven density was not at a level acceptable for commercial purposes.

[0107] The reason why the thickness of the layer of deposits on the charging roll 70 increases and the volume resistivity of the charging roll 70 increases in the comparative example will be considered below.

[0108] The removal member 72 at the contact position rotates following the charge roll 70, thereby removing the deposits adhering to the charge roll 70. However, because the removal member 72 is always disposed at the contact position, the deposits remaining on the charge roll 70 that cannot be removed by the removal member 72 are pressed against the charge roll 70 by the removal member 72, and adhere to the surface of the charge roll 70 as a layer, progressing filming. It is believed that this causes the thickness of the deposits on the charge roll 70 to increase, and the volume resistivity of the charge roll 70 to increase, in the comparative example.

[0109] (summary) As described above, in the charging device 22, the CPU 91 of the control unit 90 controls the moving member 80 to move the removal member 72 arranged at the separate position to the contact position at a predetermined time, and causes the removal member 72 to remove the deposits attached to the charging roll 70 for only the removal time. This suppresses the formation of a layer of deposits on the surface of the charging roll 70, compared to the comparative example in which the removal member that rotates following the charging roll is always in contact with the charging roll.

[0110] In addition, in the charging device 22, after the number of images since the previous removal of the adhesion reaches a predetermined number, the removal member 72 arranged at the separate position is moved to the contact position, and the adhesion adhered to the charging roll 70 is removed by the removal member 72 for the removal time. This effectively prevents a layer of adhesion from being formed on the surface of the charging roll 70, compared to the case where the adhesion is removed at predetermined time intervals.

[0111] In addition, in the charging device 22, after the number of images since the previous removal of adhesions reaches a predetermined number and during non-image formation, the removal member 72 arranged at the separate position is moved to the contact position, and adhesions adhering to the charging roll 70 are removed by the removal member 72 for only the removal time. This stabilizes the rotation of the charging roll 70 during image formation compared to the case where the removal member arranged at the separate position is moved to the contact position during image formation, thereby suppressing deterioration of image quality. Here, during non-image formation means a state in which a print job is not being executed.

[0112] Furthermore, in the image forming apparatus 10, by providing the charging device 22, density unevenness in the output image is suppressed, compared to a case where a charging device is provided in which the removing member is always in contact with the charging roll.

[0113] <Second embodiment> Next, an example of a charging device and an image forming apparatus according to a second embodiment will be described with reference to Figures 10 and 11. Regarding the second embodiment, differences from the first embodiment will be mainly described.

[0114] [Control unit 190] -Hardware configuration of the control unit 190- 10A, the control unit 190 of the charging device 122 of the second embodiment has a CPU (Central Processing Unit) 191, a ROM (Read Only Memory) 192, a RAM (Random Access Memory) 193, a storage 194, and a communication interface (I / F) 195. Each component is connected to each other so as to be able to communicate with each other via a bus 199. The charging device 122 is an example of a charging system, and the CPU 191 is an example of a processor.

[0115] -Functional configuration of the control unit 190- 10(B), the control unit 190 has a receiving unit 196, a determining unit 197, and an operating unit 198. Each functional configuration is realized by the CPU 191 reading and executing a driving program stored in the ROM 192 or the storage 194. The control unit 190 will be described in detail together with its operation, which will be described later.

[0116] (Function of main components) Next, a removal process for removing the deposits adhering to the charging roll 70 using the removing member 72 will be described with reference to the flow chart of FIG.

[0117] When the receiving unit 196 of the control unit 190 receives from the control unit 68 of the image forming apparatus 10 information about a print job to be executed by the image forming apparatus 10, in step S1100, the judgment unit 197 of the control unit 190 judges, based on the print job information, whether the number of cycles (number of rotations) of the image carrier 21 since the previous removal has reached a threshold value.

[0118] Specifically, the determination unit 197 determines whether the number of cycles of the image carrier 21 reaches a threshold value when the removal member 72 moves to the contact position to remove the deposits on the charging roll 70 and then executes the received print job. In the present embodiment, as an example, the threshold value of the number of cycles of the image carrier 21 is 200,000 [cycles]. That is, the determination unit 197 determines whether the cumulative number of cycles of the image carrier 21 reaches 200,000 [cycles] (200 kcycles) when the removal member 72 moves to the contact position to remove the deposits on the charging roll 70 and then executes the received print job. If the number of cycles of the image carrier 21 reaches 200,000 [cycles] (200 kcycles), the process proceeds to step S1200, and if the number of cycles of the image carrier 21 does not reach 200,000 [cycles] (200 kcycles), the process of step S1100 is performed again.

[0119] In step S1200, receiving unit 196 receives operation information of image forming apparatus 10 from control unit 68 of image forming apparatus 10, and determination unit 197 determines whether the print job has ended. If the print job has ended, the process proceeds to step S1300, and if the print job has not ended, the process of step S1200 is performed again.

[0120] In step S1300, the operating unit 198 energizes the solenoid 84 and moves the removal member 72 from the separated position (see FIG. 5B) to the contact position (see FIG. 5A) for a predetermined time. The removal member 72 that has moved to the contact position rotates following the rotating charging roll 70 and scrapes off and removes the deposits that have adhered to the charging roll 70. In this embodiment, as an example, the predetermined time for the number of images is set to 120 [sec]. In other words, the removal time for removing the deposits is set to 120 [sec]. When the removal member 72 reaches 120 [sec] after moving to the contact position, the operating unit 198 de-energizes the solenoid 84 and moves the removal member 72 from the contact position (see FIG. 5A) to the separated position (see FIG. 5B). When the removal member 72 moves to the separated position, the process proceeds to step S1400.

[0121] In step S1400, receiving unit 196 receives information on the presence or absence of a print job to be executed by image forming apparatus 10 from control unit 68 of image forming apparatus 10, and if there is a print job, the process returns to step S1100 again to execute the above-mentioned process. On the other hand, if there is no print job, the example operation is terminated.

[0122] - Actual machine testing - The following actual test was conducted using a DocuCentreVI C7771 manufactured by Fujifilm Business Innovation Co., Ltd. The conditions, evaluation items, and evaluation results of the actual test are explained below.

[0123] (1) Example 4 Evaluation conditions

[0124] In Example 4, the threshold value of the number of cycles of the image carrier 21 was set to 200,000 [cycles] (200 kcycles). That is, the removal member 72 was moved to the contact position every 200,000 [cycles] (200 kcycles). The removal time was set to 120 [sec]. That is, the contact state of the removal member 72 was maintained for 120 [sec]. Other conditions were the same as those in Example 1.

[0125] Evaluation items The evaluation items are the same as those in the first embodiment.

[0126] Evaluation results In Example 4, the change in volume resistivity of the charging roll 70 after printing 250,000 sheets (250 kPV) was 0.2 [Ωcm], as shown in the table in FIG. 9, which met the target.

[0127] In Example 4, the thickness of the layer of deposits on the charging roll 70 after printing 250,000 sheets (250 kPV) is 0.2 μm, as shown in the table in Fig. 9. In this way, the thickness of the layer of deposits is less than 2.0 μm, which meets the target.

[0128] In Example 4, the grade of density unevenness of the output image after printing 250,000 sheets (250 kPV) was "Good" as shown in the table in Fig. 9. In other words, the density unevenness is at an acceptable level for commercial products.

[0129] (summary) As described above, in the charging device 122, after the number of cycles of the image carrier 21 since the previous removal of the deposit reaches a predetermined number, the removal member 72 arranged at the separate position is moved to the contact position, and the deposit attached to the charging roll 70 is removed by the removal member 72 for the removal time. This effectively prevents a layer of deposits from being formed on the surface of the charging roll 70, compared to the case where the deposits are removed at predetermined time intervals.

[0130] In addition, in the charging device 122, after the number of cycles of the image carrier 21 since the previous removal of the adhesion reaches a predetermined number and during non-image formation, the removal member 72 arranged at the separate position is moved to the contact position, and the adhesion adhered to the charging roll 70 is removed by the removal member 72 for only the removal time. This stabilizes the rotation of the charging roll 70 during image formation, as compared to the case where the removal member arranged at the separate position is moved to the contact position during image formation, thereby suppressing deterioration of image quality.

[0131] <Third embodiment> Next, an example of a charging device and an image forming apparatus according to a third embodiment will be described with reference to Fig. 12 and Fig. 13. Regarding the third embodiment, differences from the first embodiment will be mainly described.

[0132] 12, the charging device 222 according to the third embodiment includes a resistance detector 224 that detects the electrical resistance between the charging roll 70 and the image carrier 21. The charging device 222 is an example of a charging system, and the resistance detector 224 is an example of a detection unit.

[0133] [Control unit 290] -Hardware configuration of the control unit 290- 13A, the control unit 290 of the charging device 222 includes a CPU (Central Processing Unit) 291, a ROM (Read Only Memory) 292, a RAM (Random Access Memory) 293, a storage 294, and a communication interface (I / F) 295. Each component is connected to each other so as to be able to communicate with each other via a bus 299. The CPU 291 is an example of a processor.

[0134] -Functional configuration of the control unit 290- 13(B), the control unit 290 has a receiving unit 296, a determining unit 297, and an operating unit 298. Each functional configuration is realized by the CPU 291 reading and executing a driving program stored in the ROM 292 or the storage 294. Details of the control unit 290 will be described below together with the operation.

[0135] (Function of main components) Next, a removing process for removing the deposits adhered to the charging roll 70 by using the removing member 72 will be described with reference to the flow chart of FIG.

[0136] The receiving unit 296 of the control unit 290 receives from the control unit 68 of the image forming apparatus 10 print job information to be executed in the image forming apparatus 10, and upon receiving from the resistance detector 224 the electrical resistance between the charging roll 70 and the image carrier 21 after the previous removal of adhesions, in step S2100 the receiving unit 296 monitors the electrical resistance detected by the resistance detector 224 during image formation, and the judgment unit 297 judges based on the monitored electrical resistance whether the electrical resistance has increased by a predetermined amount since the previous removal.

[0137] Specifically, the determination unit 297 determines whether or not the increase in electrical resistance reaches a threshold value after the removal member 72 moves to the contact position and removes the deposits from the charging roll 70. In the present embodiment, the threshold value of the increase in electrical resistance is, for example, 1.0 [log Ω]. That is, the determination unit 297 determines whether or not the increase in electrical resistance reaches 1.0 [log Ω] after the removal member 72 moves to the contact position and removes the deposits from the charging roll 70. If the increase in electrical resistance reaches 1.0 [log Ω], the process proceeds to step S2200, and if the increase in electrical resistance does not reach 1.0 [log Ω], the process of step S2100 is performed again.

[0138] In step S2200, receiving unit 296 receives operation information of image forming apparatus 10 from control unit 68 of image forming apparatus 10, and determination unit 297 determines whether the print job has ended. If the print job has ended, the process proceeds to step S2300, and if the print job has not ended, the process of step S2200 is performed again.

[0139] In step S2300, the operating unit 298 energizes the solenoid 84, and moves the removal member 72 from the separated position (see FIG. 5B) to the contact position (see FIG. 5A) for a predetermined time. The removal member 72 that has moved to the contact position rotates following the rotating charging roll 70, and scrapes off and removes the deposits that have adhered to the charging roll 70. In this embodiment, as an example, the predetermined time for the number of images is set to 60 [sec]. That is, the removal time for removing the deposits is set to 60 [sec]. When the removal member 72 reaches 60 [sec] after moving to the contact position, the operating unit 298 de-energizes the solenoid 84, and moves the removal member 72 from the contact position (see FIG. 5A) to the separated position (see FIG. 5B). When the removal member 72 moves to the separated position, the process proceeds to step S2400.

[0140] In step S2400, the receiving unit 296 receives information on the presence or absence of a print job to be executed by the image forming apparatus 10 from the control unit 68 of the image forming apparatus 10, and if there is a print job, the process returns to step S2100 again to execute the above-mentioned process. On the other hand, if there is no print job, the operation of the example is terminated.

[0141] In step S2300, the removal time is set to 60 seconds, but the control unit 290 may derive the difference in electrical resistance before and after removal of the deposit, and when the difference in electrical resistance is small, the next removal time may be made longer than when the difference in electrical resistance is large. This allows the deposits adhering to the charging roll 70 to be removed more effectively than when the removal time is always the same.

[0142] - Actual machine testing - The following actual test was conducted using a DocuCentreVI C7771 manufactured by Fujifilm Business Innovation Co., Ltd. The specifications, evaluation items, and evaluation results of the actual test are explained below.

[0143] (1) Example 5 Evaluation conditions In Example 5, the threshold value of the increase in electrical resistance was set to 1.0 [log Ω]. In other words, the removal member 72 was moved to the contact position every time the electrical resistance increased by 1.0 [log Ω]. The removal time was set to 60 [sec]. In other words, the contact state of the removal member 72 was maintained for 60 [sec]. The other conditions were the same as those in Example 1.

[0144] Evaluation items The evaluation items are the same as those in the first embodiment.

[0145] Evaluation results In Example 5, the change in volume resistivity of the charging roll 70 after printing 250,000 sheets (250 kPV) was 0.4 [Ωcm], as shown in the table in FIG. 9, which met the target.

[0146] In Example 5, the thickness of the layer of deposits on the charging roll 70 after printing 250,000 sheets (250 kPV) is 0.4 μm, as shown in the table in Fig. 9. In this way, the thickness of the layer of deposits is less than 2.0 μm, which meets the target.

[0147] In Example 5, the grade of density unevenness of the output image after printing 250,000 sheets (250 kPV) was "Good" as shown in the table in Fig. 9. In other words, the density unevenness is at an acceptable level for commercial products.

[0148] (summary) As described above, in the charging device 222, after the electrical resistance has increased by a predetermined amount since the previous removal of the deposit, the removal member 72 disposed at the separate position is moved to the contact position, and the deposit adhering to the charging roll 70 is removed by the removal member 72 for the removal time. This effectively prevents a layer of deposits from being formed on the surface of the charging roll 70, compared to the case where the deposits are removed at predetermined time intervals.

[0149] In addition, in the charging device 122, after the electrical resistance has increased by a predetermined amount since the previous removal of the adhesion, and during non-image formation, the removal member 72 disposed at the separate position is moved to the contact position, and the adhesion adhered to the charging roll 70 is removed by the removal member 72 for only the removal time. This stabilizes the rotation of the charging roll 70 during image formation, as compared to the case where the removal member disposed at the separate position is moved to the contact position during image formation, thereby suppressing deterioration in image quality.

[0150] Although the present disclosure has been described in detail with respect to a specific embodiment, it is clear to those skilled in the art that the present disclosure is not limited to the embodiment, and various other embodiments are possible within the scope of the present disclosure. For example, in the above embodiment, a removal operation for removing the adhering matter is performed during non-image formation, but a removal operation for removing the adhering matter may be performed during image formation. However, in this case, the effect of removing the adhering matter during non-image formation is not achieved.

[0151] Although not specifically described in the above embodiment, the removal operation may be performed at predetermined time intervals. In this case, however, the effect of performing the removal operation based on the number of images, the number of cycles of the image carrier 21, or the increase in electrical resistance is not achieved.

[0152] Furthermore, the threshold value for the number of images described in the first embodiment is merely an example, and other threshold values ​​may be used.

[0153] Furthermore, the threshold value of the number of cycles of the image carrier 21 described in the second embodiment is merely an example, and other threshold values ​​may be used.

[0154] Moreover, the threshold value of the increase in electrical resistance described in the third embodiment is merely an example, and other threshold values ​​may be used.

[0155] In addition, in the above embodiment, the removal time is described as an example, but the actual removal time may be shorter or longer than the described removal time.

[0156] In the above embodiment, the control units 90, 190, 290 of the charging devices 22, 122, 222 are provided separately from the control unit 68 of the image forming apparatus 10. However, the control units of the charging devices may form part of the control unit 68 of the image forming apparatus 10.

[0157] Although not specifically described in the above embodiment, the charging devices 22, 122, 222 and the image forming apparatus 10 may be configured as a single device, or may be configured as a plurality of devices.

[0158] (((1))) a charging member that rotates in accordance with the rotation of the image carrier and charges the image carrier; a removal member that is disposed at a contact position where it contacts the charging member and rotates in accordance with the rotation of the charging member to remove deposits that have adhered to the charging member; and a moving member that moves the removing member between a spaced position spaced from the charging member and the contact position; at least one processor; the processor controls the moving member to move the removal member disposed at the separated position to the contact position at a predetermined time, and causes the removal member to remove the deposit attached to the charged member for a removal time. Charging system.

[0159] (((2))) The processor, after the number of images formed on the image carrier since the previous removal of the deposit reaches a predetermined number, the removing member disposed at the separated position is moved to the contact position, and the deposit attached to the charging member is removed by the removing member for the removal time. The charging system according to (((1))).

[0160] (((3))) The processor, after the number of images since the previous removal of the adhering matter reaches a predetermined number, and during non-image formation, the removing member disposed at the separated position is moved to the contact position; The charging system according to (((1))) or (((2))).

[0161] (((4))) The processor, after the number of cycles of the image carrier since the previous removal of the deposit reaches a predetermined number, the removing member disposed at the separated position is moved to the contact position, and the deposit attached to the charging member is removed by the removing member for the removal time. The charging system according to (((1))).

[0162] (((5))) The processor, after the number of cycles since the previous removal of the deposit reaches a predetermined number, and during non-image formation, the removing member disposed at the separated position is moved to the contact position; The charging system according to (((1))) or (((4))).

[0163] (((6))) a detection unit for detecting an electrical resistance between the charging member and the image carrier, The processor, after the electrical resistance has increased by a predetermined amount since the previous removal of the deposit, the removing member disposed at the separated position is moved to the contact position, and the deposit attached to the charged member is removed by the removing member for the removal time. The charging system according to (((1))).

[0164] (((7))) The processor, after an increase in the electrical resistance from the previous removal of the deposit reaches a predetermined threshold value, and during non-image formation, the removal member disposed at the separated position is moved to the contact position; Charging system according to (((1))) or (((6))).

[0165] (((8))) The processor, A difference in the electrical resistance before and after removal of the deposit is derived; When the difference in electrical resistance is small, the next removal time is made longer than when the difference in electrical resistance is large. The charging system according to (((6))) or (((7))).

[0166] (((9))) A charging system according to any one of (((1))) to (((8))), an image carrier on which an image is formed and which is charged by the charging system; a transfer device for transferring the image formed on the image carrier onto a recording medium; An image forming system comprising:

[0167] According to the charging system (((1))), the formation of a layer of adhesions on the charged member can be suppressed compared to a case in which the removal member, which rotates in response to the charged member, is constantly in contact with the charged member.

[0168] According to the charging system (((2))), it is possible to suppress the formation of a layer of adhering matter on the charging member, compared to a case in which the adhering matter is removed at predetermined time intervals.

[0169] According to the charging system (((3))), degradation of image quality can be suppressed compared to a case in which the removing member disposed at the separate position is moved to the contact position during image formation.

[0170] According to the charging system (((4))), the formation of a layer of adhering matter on the charging member can be effectively suppressed compared to a case in which the adhering matter is removed at predetermined time intervals.

[0171] According to the charging system (((5))), degradation in image quality can be suppressed compared to a case in which the removing member disposed at the separate position is moved to the contact position during image formation.

[0172] According to the charging system (((6))), the formation of a layer of adhering matter on the charging member can be effectively suppressed compared to a case in which the adhering matter is removed at predetermined time intervals.

[0173] According to the charging system (((7))), degradation of image quality can be suppressed compared to a case in which the removing member disposed at the remote position is moved to the contact position during image formation.

[0174] According to the charging system (((8))), the matter adhering to the charging member can be removed more effectively than when the removal time is always the same.

[0175] According to the image forming system (((9))), density unevenness in the output image can be suppressed, compared to a case in which a charging system is provided in which the removing member is constantly in contact with the charging member. [Explanation of symbols]

[0176] 10 Image forming device (an example of an image forming system) 22 Charging device (an example of a charging system) 72 Removal material 80 Moving parts 91 UPC (an example of a processor) 122 Charging device (an example of a charging system) 191 UPC (an example of a processor) 222 Charging device (an example of a charging system) 224 Resistance detector (an example of a detection unit) 291 CPU (an example of a processor)

Claims

1. a charging member that rotates in accordance with the rotation of the image carrier and charges the image carrier; a removal member that is disposed at a contact position where it contacts the charging member and rotates in accordance with the rotation of the charging member to remove deposits that have adhered to the charging member; and a moving member that moves the removing member between a spaced position spaced from the charging member and the contact position; At least one processor; the processor controls the moving member to move the removal member disposed at the separated position to the contact position at a predetermined time, and causes the removal member to remove the deposit attached to the charged member for a removal time. Charging system.

2. The processor, after the number of images formed on the image carrier since the previous removal of the deposit reaches a predetermined number, the removing member disposed at the separated position is moved to the contact position, and the deposit attached to the charging member is removed by the removing member for the removal time.

2. The charging system of claim 1.

3. The processor, after the number of images since the previous removal of the adhering matter reaches a predetermined number, and during non-image formation, the removing member disposed at the separated position is moved to the contact position; 3. The charging system of claim 2.

4. The processor, after the number of cycles of the image carrier since the previous removal of the deposit reaches a predetermined number, the removing member disposed at the separated position is moved to the contact position, and the deposit attached to the charging member is removed by the removing member for the removal time.

2. The charging system of claim 1.

5. The processor, after the number of cycles since the previous removal of the deposit reaches a predetermined number, and during non-image formation, the removing member disposed at the separated position is moved to the contact position; 5. The charging system of claim 4.

6. a detection unit for detecting an electrical resistance between the charging member and the image carrier, The processor, after the electrical resistance has increased by a predetermined amount since the previous removal of the deposit, the removing member disposed at the separated position is moved to the contact position, and the deposit attached to the charged member is removed by the removing member for the removal time.

2. The charging system of claim 1.

7. The processor, after an increase in the electrical resistance from the previous removal of the deposit reaches a predetermined threshold value, and during non-image formation, the removal member disposed at the separated position is moved to the contact position; 7. The charging system of claim 6.

8. The processor, A difference in the electrical resistance before and after removal of the deposit is derived; When the difference in electrical resistance is small, the next removal time is made longer than when the difference in electrical resistance is large.

7. The charging system of claim 6.

9. A charging system according to any one of claims 1 to 8; an image carrier on which an image is formed and which is charged by the charging system; a transfer device for transferring the image formed on the image carrier onto a recording medium; An image forming system comprising:

Images