Method of using an image forming apparatus and brush

Abstract

To prevent a reduction in image quality caused by a brush.SOLUTION: An image forming apparatus comprises an image carrier 1, a brush 72 in contact with the image carrier 1, and a driving unit 75 rotating the brush 72. The driving unit 75 has a recovery mode for rotating the brush 72 to recover creep generated during the stop of the brush 72. The image forming apparatus further comprises a determination unit that determines the time required for the operation of the recovery mode according to the amount of change in the radius of the brush 72 caused by creep.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to an image forming apparatus and a method of using a brush. [Background Art]

[0002] Conventionally, in an electrophotographic image forming apparatus, removal (cleaning) of deposits such as residual toner adhering to the surface of an image bearing member (e.g., a photosensitive drum, an intermediate transfer member, etc.) on which a toner image is formed is performed. Furthermore, in order to improve the cleaning performance of the image bearing member, a lubricant is applied onto the surface of the image bearing member using a brush. However, since the brush rotates while contacting the image bearing member, rotational fluctuations of the brush propagate to the image bearing member, causing rotational unevenness in the image bearing member. As a result, color shift and pitch unevenness occur, which degrades the quality of the formed image.

[0003] Japanese Unexamined Patent Application Publication No. 2014-235223 (Patent Document 1) discloses that in order to suppress the occurrence of such color shift and pitch unevenness, the rotation cycle of the brush is controlled within ±1 / 10 of the product of the rotation cycle of the photosensitive drum, the central angle between an exposure position and a transfer position on the photosensitive drum divided by 360°, and 1 divided by a natural number. [Prior Art Literature] [Patent Literature]

[0004] [Patent Document 1] Japanese Unexamined Patent Application Publication No. 2014-235223 [Summary of the Invention] [Problem to be Solved by the Invention]

[0005] In the technology disclosed in Patent Document 1, there is a limitation on the control range of the rotation cycle of the brush, so degradation of image quality caused by the brush may occur depending on the usage time of the image forming apparatus, the operating environment, and image coverage.

[0006] This disclosure is made in view of the above-mentioned background, and its purpose is to provide an image forming apparatus and a method of using a brush that can suppress the degradation of image quality caused by the brush. [Means for solving the problem]

[0007] According to a certain aspect of this disclosure, an image forming apparatus comprises an image carrier, a brush that contacts the image carrier, and a drive unit that rotates the brush. . To recover from the creep that occurs when the Rashi is stopped The drive unit Rotate the brush to activate recovery mode. Executable The image forming apparatus further measures the change in brush radius due to creep. The larger The time required for recovery mode to operate Large It is equipped with a decision-making unit. The image forming apparatus further includes an adjustment unit that updates the required operating time for the next recovery mode to the remaining time if the operating time determined for the next recovery mode is less than the remaining time obtained by subtracting the actual operating time of the previous recovery mode from the operating time determined for the previous recovery mode.

[0008] Preferably, the determination unit estimates the amount of change from the brush's stopping time. Preferably, the determination unit estimates the amount of change from the brush's resting time and the temperature around the brush during the period the brush is resting.

[0009] Preferably, the determination unit determines the required operating time based on the brush stop time, which correlates with the amount of change.

[0010] Preferably, the determination unit determines the required operating time based on the brush stop time, which correlates with the amount of change, and the temperature around the brush during the period the brush is stopped.

[0011] Preferably, the drive unit has a normal mode, separate from the recovery mode, in which the brush rotates when an image is formed on the image carrier. The rotation speed in the recovery mode is faster than the rotation speed in the normal mode.

[0012] Preferably, the recovery mode is performed before the image is formed on the image carrier. Preferably, the recovery mode is performed in parallel with the formation of the image on the image carrier.

[0013] Preferably, the image forming apparatus is The remaining a storage unit that stores time Equipped with .

[0014] According to a certain aspect of this disclosure, an image forming apparatus comprises an image carrier, a brush in contact with the image carrier, and a drive unit for rotating the brush. A recovery mode is possible in which the drive unit rotates the brush to recover from creep that occurs when the brush is stopped. The image forming apparatus further comprises a determination unit that determines that the required operating time of the recovery mode increases as the amount of change in the radius of the brush due to creep increases. The image forming apparatus comprises: a sensor that detects the rotation phase of the brush; It includes an adjustment section. The adjustment section is a b a first rotation phase detected by the sensor when the brush is stopped most recently, and a second rotation phase detected by the sensor when the brush was stopped previously to a difference between the first rotation phase and the second rotation phase exceeds a threshold, and the remaining time is longer than the required operation time determined for the next recovery mode , the operating time of the previous recovery mode is subtracted from the operating time determined for the previous recovery mode. the required operation time determined for the next recovery mode is updated to the remaining time in response to the remaining time being longer.

[0015] Preferably, the adjustment unit extends the required operation time determined for the next recovery mode by the remaining time in response to the difference being equal to or less than the threshold. Preferably, the image forming apparatus includes a storage unit that stores the remaining time, the first rotation phase, and the second rotation phase.

[0016] Preferably, the brush applies lubricant to the image bearing member. According to one aspect of the present disclosure, a method of using a brush in contact with an image bearing member of an image forming apparatus comprises the steps of: executing a recovery mode in which the brush is rotated to recover creep occurring while the brush is stopped; and adjusting an amount of change in radius of the brush caused by creep The larger the required operation time for the recovery mode Large a step of determining If the required operating time for the next recovery mode is less than the remaining time obtained by subtracting the actual operating time of the previous recovery mode from the required operating time for the previous recovery mode, the required operating time for the next recovery mode is updated to the remaining time. . According to a certain aspect of this disclosure, a method for using a brush that contacts an image carrier in an image forming apparatus includes the steps of: executing a recovery mode in which the brush is rotated to recover from creep that occurs while the brush is stopped; determining that the required operating time of the recovery mode is greater the greater the change in the brush radius due to creep; and updating the required operating time for the next recovery mode to the remaining time, in accordance with the fact that the difference between a first rotation phase detected by a sensor that detects the rotation phase of the brush at the most recent stop of the brush and a second rotation phase detected by the sensor at the previous stop of the brush exceeds a threshold, and the remaining time obtained by subtracting the actual operating time of the previous recovery mode from the required operating time of the previous recovery mode is longer than the required operating time for the next recovery mode.

Effects of the Invention

[0017] According to the present disclosure, degradation of image quality caused by the brush can be suppressed.

Brief Description of Drawings

[0018] [Figure 1] It is a diagram showing an overall outline of the image forming apparatus according to the present embodiment. [Figure 2]Figure 1 is an enlarged view of the cleaning device and its vicinity in the image forming apparatus shown. [Figure 3] This is a block diagram showing an example of the controller's functional configuration. [Figure 4] This figure shows the change in brush radius ΔR due to creep. [Figure 5] This figure shows an example of the relationship between the brush stopping time and the change in brush radius ΔR. [Figure 6] This figure shows an example of the relationship between the change amount ΔR and the time required for the recovery mode to operate in order to recover from creep. [Figure 7] This is a flowchart illustrating the processing flow of the first specific example of recovery control. [Figure 8] This diagram shows the processing flow of the subroutine in step S1 in the first specific example of recovery control. [Figure 9] This figure shows another example of the relationship between the brush stopping time and the change in brush radius ΔR. [Figure 10] This diagram shows the processing flow of the subroutine in step S1 in the second specific example of recovery control. [Figure 11] This diagram shows the processing flow of the subroutine in step S1 in the third specific example of recovery control. [Figure 12] This diagram shows the processing flow of the subroutine in step S1 in the fourth specific example of recovery control. [Figure 13] This figure shows the relationship between the change in brush radius ΔR and the amount of brightness fluctuation in the image formed using the image carrier in contact with the brush. [Figure 14] This figure shows the stopping time of the brush when the change in brush radius reaches ΔR1. [Figure 15] This figure shows another example of the relationship between the change amount ΔR and the time required for operation. [Figure 16] This figure shows the relationship between the brush stop time and the time required for the recovery mode to operate in order to recover from the creep caused by the brush stopping for that duration. [Figure 17]This figure shows the time required to recover from brush creep with a change of ΔR1. [Figure 18] This is a flowchart illustrating the processing flow of the seventh specific example of recovery control. [Figure 19] This is a block diagram showing another example of the controller's functional configuration. [Figure 20] This flowchart shows the first half of the processing flow for the eighth specific example of recovery control. [Figure 21] This flowchart shows the flow of the latter half of the processing in the eighth specific example of recovery control. [Figure 22] This is a block diagram showing yet another example of the controller's functional configuration. [Figure 23] This flowchart shows the first half of the processing flow for the ninth specific example of recovery control. [Figure 24] This flowchart shows the flow of the latter half of the processing in the ninth specific example of recovery control. [Modes for carrying out the invention]

[0019] Embodiments and modifications according to this disclosure will be described below with reference to the drawings. In the following description, the same parts and components are denoted by the same reference numerals. Their names and functions are also the same. Therefore, detailed descriptions of them will not be repeated. The embodiments and modifications described below may be combined selectively as appropriate.

[0020] (Configuration of an image forming apparatus) The image forming apparatus according to this embodiment will be described with reference to Figures 1 and 2. Figure 1 is a diagram showing the overall schematic of the image forming apparatus according to this embodiment.

[0021] Image forming apparatus 101 is an example of an image forming apparatus that forms an image on paper using an electrophotographic method that uses static electricity to form the image. Image forming apparatus 101 forms a color image on paper by, for example, a tandem system that superimposes toner images of four colors: yellow (Y), magenta (M), cyan (C), and black (K).

[0022] As shown in Figure 1, the image forming apparatus 101 includes a controller 22, an operation display unit 23, an image input unit 24, a paper feeding unit 28, a transport unit 25, an image forming unit 26, and a paper output tray 29.

[0023] The operation display unit 23 includes a display unit consisting of a liquid crystal panel or the like, and an operation unit consisting of a touch sensor or the like. The display unit and the operation unit are integrally formed, for example, as a touch panel. The operation display unit 23 generates signals representing the operation content from the operator input to the operation unit and supplies the signals to the controller 22. For example, the operation display unit 23 generates a print instruction according to the operation content and supplies the generated print instruction to the controller 22. The print instruction is an instruction to form a specified image on a specified sheet of paper.

[0024] Furthermore, the operation display unit 23 displays operator operations, setting information, etc., on the display unit based on display signals supplied from the controller 22. It is also possible to configure the operation unit as a separate unit from the display unit, using a mouse or tablet, for example.

[0025] The image input unit 24 optically reads an image from a document on the document glass and generates image data by performing A / D conversion on the read image. The image input unit 24 can also read an image from a document on the platen glass.

[0026] The paper feeding unit 28 is equipped with a paper feeding mechanism consisting of multiple paper trays, a paper feeding roller, a separation roller, a paper feeding / separation rubber, a feed roller, etc., provided for each paper tray. Each paper tray stores pre-identified paper according to its type (paper type, basis weight, paper size, etc.), and the paper is transported one sheet at a time from the top towards the transport unit 25 by the paper feeding mechanism.

[0027] The transport unit 25 includes multiple transport rollers for transporting paper, and transports the paper fed from the paper feeding unit 28 to the output tray 29 via the image forming unit 26.

[0028] The image forming unit 26 performs an electrophotographic image forming process to form an image consisting of four colors, C, M, Y, and K, on ​​the paper. The image forming unit 26 includes four image forming units 10 for forming Y, M, C, and K toner images, an intermediate transfer belt 12, a transfer unit 14, and a fixing device 16.

[0029] The four image forming units 10 are arranged in series (tandem) along the belt surface of the intermediate transfer belt 12, and each forms a C, M, Y, and K toner image. The four image forming units 10 have the same configuration, differing only in the color of the toner image they form. As shown in Figure 1, each of the four image forming units 10 includes an image carrier 1, a charging device 2, an exposure device 3, a developing device 4, a primary transfer roller 5, and a cleaning device 7. The image carrier 1 is a photosensitive drum.

[0030] Each image forming unit 10 charges the surface of the image carrier 1 with the charging device 2, and then irradiates the image carrier 1 with light from the exposure device 3 based on the job that has been fed in, thereby forming an electrostatic latent image on the image carrier 1. Next, toner is supplied onto the image carrier 1 by the developing device 4, and a toner image is formed on the image carrier 1. The toner image formed on the image carrier 1 is transferred (primary transfer) onto the intermediate transfer belt 12 by the primary transfer roller 5. As a result, a toner image consisting of each color is formed on the intermediate transfer belt 12. After the primary transfer, the cleaning device 7 removes any toner remaining on the image carrier 1.

[0031] The transfer unit 14 transfers the toner image on the intermediate transfer belt 12 onto the paper (secondary transfer). The fuser unit 16 heats and pressurizes the paper on which the toner image has been transferred to perform a fixing process. The paper on which the toner image has been fixed by the fuser unit 16 is transported to the output tray 29 by the transport unit 25.

[0032] The controller 22 controls the operation of each part of the image forming apparatus 101 in response to inputs to the operation display unit 23. For example, the controller 22 controls the image forming unit 26 in response to a print instruction.

[0033] Figure 2 is an enlarged view of the cleaning device 7 and its vicinity in the image forming apparatus shown in Figure 1. As shown in Figure 2, the cleaning device 7 includes a cleaning blade 71, a brush 72, a solid lubricant 73, a fixed blade 74, a drive unit 75, and a phase sensor 76.

[0034] The cleaning blade 71 has a counter-type configuration in which its tip (edge) is brought into contact with the image carrier 1 in the direction opposite to the rotational direction of the image carrier 1. Specifically, the cleaning blade 71 is positioned to slide against the rotational direction R1 of the image carrier 1 from a counter-direction in which the edge is taut, at a predetermined contact angle and penetration depth. With this configuration, the cleaning blade 71 slides against the surface of the image carrier 1 to remove residual toner remaining on the surface of the image carrier 1 after primary transfer. The cleaning blade 71 is manufactured, for example, by forming an elastic material such as urethane rubber into a flat sheet. Note that the contact method of the cleaning blade 71 with the image carrier 1 is not limited to the counter-type, but may also be a with-type.

[0035] The brush 72 is roller-shaped and applies lubricant to the surface of the image carrier 1. The lubricant reduces the adhesion of toner to the image carrier 1. The brush 72 is made by winding a base cloth with fibers such as polyester implanted around a shaft 72a that serves as the axis of rotation. The brush 72 has a width approximately equal to the axial width of the image carrier 1. The brush 72 is positioned to contact the surface of the solid lubricant 73 and the surface of the image carrier 1, and rotates, for example, in the same rotational direction R2 as the rotational direction R1 of the image carrier 1, to supply lubricant to the surface of the image carrier 1.

[0036] The brush 72 contacts the image carrier 1 at the contact portion 8. When the brush 72 is stationary, creep may occur in the fibers of the brush 72 that are in contact with the image carrier 1. Creep is a phenomenon in which the shape of the fibers remains bent.

[0037] The fixing blade 74 has a trail-type configuration in which its tip (edge) contacts the image carrier 1 along the rotational direction R1. Specifically, the fixing blade 74 is positioned to slide against the image carrier 1 at a predetermined contact angle and penetration amount from the trail direction, which is the direction in which the edge is dragged relative to the rotational direction R1. With this configuration, the fixing blade 74 slides against the surface of the image carrier 1, spreading and fixing the lubricant supplied onto the image carrier 1. The fixing blade 74, like the cleaning blade 71, is manufactured by molding an elastic material such as urethane rubber into a flat sheet.

[0038] The drive unit 75 rotates the brush 72. The drive unit 75 rotates the brush 72 in response to commands from the controller 22. As the brush 72 rotates, lubricant is supplied to the surface of the image carrier 1. Also, if creep occurs, rotating the brush 72 returns the shape of the fibers to their original state. In this specification, the return of bent fibers in the brush 72 to their original state is referred to as "creep recovery." Therefore, the drive unit 75 has a normal mode in which the brush 72 is rotated when a toner image is formed on the image carrier 1, and a recovery mode in which the brush 72 is rotated to recover creep that occurs when the brush 72 is stopped. The rotation speed of the brush 72 in the recovery mode may be the same as the rotation speed of the brush 72 in the normal mode, or it may be greater than the rotation speed of the brush 72 in the normal mode. For example, the rotation speed of the brush 72 in the recovery mode is 1.1 times the rotation speed of the brush 72 in the normal mode.

[0039] The phase sensor 76 measures the rotational phase of the brush 72. The rotational phase is represented, for example, by the rotation angle of the brush 72 from a reference state. The phase sensor 76 includes, for example, an encoder. The phase sensor 76 outputs the measurement result to the controller 22.

[0040] As shown in Figures 1 and 2, the image forming unit 26 includes a temperature sensor 18 that measures the temperature around the brush 72. The temperature sensor 18 outputs the measurement result to the controller 22.

[0041] The controller 22 includes a processor 221 such as a CPU (Central Processing Unit), memory 222 such as RAM (Random Access Memory), and storage 223 such as ROM (Read Only Memory) and HDD (Hard Disk Drive).

[0042] The storage 223 stores the program executed by the processor 221, as well as data used during program execution. The processor 221 controls each part of the image forming apparatus 101 by reading the program stored in the storage 223. Variables and parameters generated during the calculation process of the processor 221 are temporarily written to the memory 222.

[0043] (Example of controller processing) The controller 22 performs control related to the recovery of the brush 72's creep (hereinafter referred to as "recovery control"). A specific example of recovery control is described below.

[0044] <First specific example of recovery control> Figure 3 is a block diagram showing an example of the controller's functional configuration. Figure 3 shows the configuration related to recovery control. As shown in Figure 3, the controller 22 includes a memory unit 30, a stop time measurement unit 31, a determination unit 32, a rotation control unit 33, and a counter 34. The memory unit 30 is implemented by the memory 222 and storage 223 shown in Figure 2. The stop time measurement unit 31, the determination unit 32, the rotation control unit 33, and the counter 34 are implemented by the processor 221 shown in Figure 2 executing a program. Alternatively, some or all of the stop time measurement unit 31, the determination unit 32, the rotation control unit 33, and the counter 34 may be implemented using dedicated hardware circuits (e.g., ASIC or FPGA).

[0045] The stop time measurement unit 31 starts measuring the time the brush 72 is stopped rotating (hereinafter referred to as "stop time") each time the brush 72 stops rotating. The stop time measurement unit 31 measures the stop time using power supplied from a commercial power source or a rechargeable battery. Therefore, the stop time measurement unit 31 can continue measuring the stop time even when the main power supply of the image forming apparatus 101 is turned off. The stop time measurement unit 31 updates the stop time information 30a stored in the storage unit 30 according to the measurement result. The stop time information 30a indicates the stop time measured by the stop time measurement unit 31.

[0046] The stop time measurement unit 31 resets the measured stop time to 0 as the brush 72 rotates. In other words, the stop time measurement unit 31 updates the stop time information 30a to show 0.

[0047] The determination unit 32 determines the required operating time of the recovery mode of the drive unit 75 according to the amount ΔR of change in the radius of the brush 72 due to creep. The required operating time is the operating time of the recovery mode required to completely recover from creep. The determination unit 32 updates the remaining time information 30b stored in the storage unit 30 to show the determined required operating time. The remaining time information 30b shows the difference between the required operating time determined by the determination unit 32 and the actual operating time of the recovery mode (hereinafter referred to as "remaining time").

[0048] Figure 4 shows the change in brush radius ΔR due to creep. The change ΔR is the difference between the radius of the brush 72 in areas where creep does not occur and the radius of the brush 72 in areas where creep occurs.

[0049] Figure 5 shows an example of the relationship between the brush stopping time and the change in brush radius ΔR. The relationship shown in Figure 5 is determined in advance through experiments or other means. The determination unit 32 stores in advance the first correlation information showing the relationship in Figure 5, and estimates the current change ΔR based on the first correlation information and the stopping time information 30a stored in the storage unit 30. The first correlation information is, for example, a table showing the correspondence between stopping time and change ΔR, or a relationship formula between stopping time and change ΔR.

[0050] Figure 6 shows an example of the relationship between the change amount ΔR and the required operating time of the recovery mode necessary to recover creep. The relationship shown in Figure 6 is determined in advance through experiments or other means. In Figure 6, the solid line 40 shows the relationship between the change amount ΔR and the required operating time when the rotational speed of the recovery mode is the same as the rotational speed of the normal mode. The solid line 42 shows the relationship between the change amount ΔR and the required operating time when the rotational speed of the recovery mode is 1.1 times the rotational speed of the normal mode. The determination unit 32 stores the second correlation information showing the relationship in Figure 6 in advance, and determines the required operating time of the recovery mode based on the second correlation relationship and the change amount ΔR. The second correlation information is, for example, a table showing the correspondence between the change amount ΔR and the required operating time, or a relationship formula between the change amount ΔR and the required operating time.

[0051] For example, if the rotation speed in recovery mode and the rotation speed in normal mode are the same, the determination unit 32 stores in advance a table or relational expression showing the relationship indicated by the solid line 40 in Figure 6, and determines the required operating time based on the said table or relational expression and the current change amount ΔR. If the rotation speed in recovery mode is 1.1 times the rotation speed in normal mode, the determination unit 32 stores in advance a table or relational expression showing the relationship indicated by the solid line 42 in Figure 6, and determines the required operating time based on the said table or relational expression and the current change amount ΔR.

[0052] The rotation control unit 33 shown in Figure 3 controls the drive unit 75 to rotate the brush 72. Specifically, the rotation control unit 33 controls the drive unit 75 to start the recovery mode operation in response to the main power supply of the image forming apparatus 101 being turned on. As a result, the recovery mode is performed before the toner image is formed on the image carrier 1.

[0053] The counter 34 operates during the recovery mode operation and counts the time. The rotation control unit 33 updates the remaining time information 30b stored in the memory unit 30 based on the count result of the counter 34. Specifically, the rotation control unit 33 updates the remaining time information 30b to show the difference (remaining time) between the required operation time determined by the determination unit 32 and the actual operating time of the recovery mode.

[0054] The rotation control unit 33 controls the drive unit 75 to terminate the operation in recovery mode in response to the remaining time information 30b indicating a threshold Th1. In the first specific example, the threshold Th1 is 0. After the operation in recovery mode is terminated, the rotation control unit 33 controls the drive unit 75 to start the operation in normal mode.

[0055] Figure 7 is a flowchart showing the processing flow of a first specific example of recovery control. The flow shown in Figure 7 is executed in response to the main power supply of the image forming apparatus 101 being turned on.

[0056] First, the determination unit 32 of the controller 22 determines the required operating time for the recovery mode according to the amount ΔR of change in the radius of the brush 72 due to creep (step S1). The determination unit 32 sets the determined required operating time as the remaining time (step S2). Specifically, the determination unit 32 updates the remaining time information 30b to indicate the determined required operating time.

[0057] Next, the rotation control unit 33 of the controller 22 controls the drive unit 75 to start the recovery mode operation (step S3). In step S3, the rotation control unit 33 activates the counter 34. The counter 34 then measures the time elapsed since step S3.

[0058] Next, the rotation control unit 33 updates the remaining time information 30b so that the remaining time indicated by the remaining time information 30b is shortened by the measurement time of the counter 34 (step S4). Along with updating the remaining time information 30b, the rotation control unit 33 also resets the measurement time of the counter 34 to 0. As a result, the counter 34 measures the time from step S4.

[0059] Next, the rotation control unit 33 determines whether the remaining time indicated by the remaining time information 30b exceeds a predetermined threshold Th1 (step S5). In the first specific example, the threshold Th1 is set to 0.

[0060] If the remaining time exceeds the threshold Th1 (YES in step S5), the rotation control unit 33 controls the drive unit 75 to continue operation in recovery mode (step S6). After step S6, the process returns to step S4.

[0061] If the remaining time does not exceed the threshold Th1 (NO in step S5), the rotation control unit 33 controls the drive unit 75 to terminate the operation in recovery mode and start the operation in normal mode (step S7). After step S7, the process ends.

[0062] Figure 8 shows the processing flow of the subroutine in step S1 in the first specific example of recovery control. As shown in Figure 8, the determination unit 32 refers to the stop time information 30a stored in the storage unit 30 and reads the stop time of the brush 72 (step S101).

[0063] Next, the determination unit 32 uses the first correlation information shown in Figure 5 to estimate the change in the radius of the brush 72 ΔR from the stopping time (step S102).

[0064] Next, the determination unit 32 uses the second correlation information shown in Figure 6 to determine the required operating time from the change amount ΔR (step S103). After step S103, the process returns to step S2 in Figure 7.

[0065] According to the first specific example of recovery control, when the main power supply of the image forming apparatus 101 is turned on, a recovery mode is automatically activated to recover from creep caused by the stopping of the brush 72. The required operating time of the recovery mode is appropriately determined according to the amount of change ΔR in the radius of the brush 72 due to creep. As a result, creep is recovered by implementing the recovery mode. Consequently, the deterioration of image quality caused by the brush 72 is suppressed.

[0066] <Second specific example of recovery control> Figure 9 shows another example of the relationship between the brush stopping time and the change in brush radius ΔR. The relationship shown in Figure 9 is determined in advance through experiments, etc. In Figure 9, the solid line 50 shows the relationship between the stopping time and the change in ΔR when the ambient temperature around the brush 72 is 20°C. The solid line 52 shows the relationship between the stopping time and the change in ΔR when the ambient temperature around the brush 72 is 50°C. As shown in Figure 9, the relationship between the stopping time and the change in ΔR depends on the ambient temperature around the brush 72 while it is stopped. That is, if the ambient temperature around the brush 72 is high, the fibers tend to collapse, and creep progresses in a relatively short time. Therefore, the determination unit 32 of the controller 22 may estimate the change in ΔR from the stopping time, taking into account the temperature measured by the temperature sensor 18 during the period when the brush 72 is stopped.

[0067] In the second specific example of recovery control, the controller 22 has the functional configuration shown in Figure 3. However, the determination unit 32 pre-stores first correlation information that shows the relationship between the stop time and the change amount ΔR for each ambient temperature around the brush 72. The determination unit 32 identifies the first correlation information corresponding to the representative value of the temperature measured by the temperature sensor 18 during the period when the brush 72 is stopped, and estimates the current change amount ΔR based on the identified first correlation information and the stop time indicated by the stop time information stored in the storage unit 30. The representative value of the measured temperature is, for example, the average value of the measured temperature during the period when the brush 72 was stopped, or the maximum value of the measured temperature during the period when the brush 72 was stopped.

[0068] The processing flow of the second specific example of recovery control is shown by the flowchart in Figure 7, similar to the first specific example. However, the processing flow of the subroutine in step S1 follows the flowchart in Figure 10.

[0069] Figure 10 shows the processing flow of the subroutine in step S1 in a second specific example of recovery control. The flowchart in Figure 10 differs from the flowchart in Figure 8 in that it includes steps S104 and S105 instead of step S102. Therefore, only steps S104 and S105 will be explained.

[0070] In step S104, the determination unit 32 obtains the measured temperature around the brush 72 during the period when the brush 72 is stopped. For example, the determination unit 32 stores a temperature history that associates the measured temperature from the temperature sensor 18 with the measurement time, and obtains the temperature around the brush 72 during the period when the brush 72 is stopped from this temperature history.

[0071] In step S105, following step S104, the determination unit 32 uses the first correlation information corresponding to the representative value of the acquired measured temperature to estimate the change in the radius ΔR of the brush 72 from the stopping time.

[0072] According to a second specific example of recovery control, the change in the radius of the brush 72 due to creep, ΔR, is accurately estimated by considering the ambient temperature around the stopped brush 72. Therefore, the required operating time for the recovery mode is also determined more appropriately according to the change in ΔR. As a result, creep is more reliably recovered by implementing the recovery mode.

[0073] In the third specific example of recovery control, the controller 22 also has the functional configuration shown in Figure 3. However, in the first specific example described above, the determination unit 32 estimates the change amount ΔR from the stop time using the first correlation information and calculates the required operating time from the change amount ΔR using the second correlation information. In contrast, in the third specific example of recovery control, the determination unit 32 determines the required operating time based on the stop time correlated with the change amount ΔR.

[0074] Specifically, the determination unit 32 stores third correlation information that shows the relationship between the stopping time of the brush 72 and the required operating time of the recovery mode to recover the creep caused by the stopping for that duration. The third correlation information is generated in advance by combining the first correlation information and the second correlation information. The determination unit 32 can then use the third correlation information to determine the required operating time from the stopping time.

[0075] The processing flow of the third specific example of recovery control is shown by the flowchart in Figure 7, similar to the first specific example. However, the processing flow of the subroutine in step S1 follows the flowchart in Figure 11.

[0076] Figure 11 shows the processing flow of the subroutine in step S1 in a third specific example of recovery control. The flowchart in Figure 11 differs from the flowchart in Figure 8 in that it includes step S106 instead of steps S102 and S103. Therefore, only step S106 will be explained.

[0077] In step S106, the determination unit 32 uses the pre-stored third correlation information to determine the required operating time from the stop time read in step S101.

[0078] According to a third specific example of recovery control, the required operating time for the recovery mode is appropriately determined according to the stopping time of the brush 72, which correlates with the change in the radius of the brush 72 due to creep ΔR. Therefore, creep is recovered by implementing the recovery mode. As a result, the degradation of image quality caused by the brush 72 is suppressed.

[0079] <Fourth specific example of recovery control> The fourth specific example of recovery control is an example that combines the second and third specific examples. In the fourth specific example of recovery control, the controller 22 also has the functional configuration shown in Figure 3.

[0080] As explained with reference to Figure 9, the relationship between the stop time and the change amount ΔR depends on the temperature around the brush 72 while it is stopped. Therefore, the relationship between the stop time of the brush 72 and the required operating time of the recovery mode to recover the creep caused by the stop for that duration also depends on the temperature around the brush 72 while it is stopped. Thus, in the fourth specific example of recovery control, the determination unit 32 determines the required operating time based on the stop time of the brush 72 and the temperature around the brush 72 during the period the brush 72 is stopped, which are correlated with the change amount ΔR.

[0081] Specifically, the determination unit 32 pre-stores third correlation information indicating the relationship between the stop time and the required operating time for each ambient temperature around the brush 72. The determination unit 32 identifies the third correlation information corresponding to the representative value of the temperature measured by the temperature sensor 18 when the brush 72 was stopped, and uses the identified third correlation information to determine the required operating time from the stop time.

[0082] The processing flow of the fourth specific example of recovery control is shown by the flowchart in Figure 7, similar to the first specific example. However, the processing flow of the subroutine in step S1 follows the flowchart in Figure 12.

[0083] Figure 12 shows the processing flow of the subroutine in step S1 in the fourth specific example of recovery control. The flowchart in Figure 12 differs from the flowchart in Figure 10 in that it includes step S107 instead of steps S105 and S103. Therefore, only step S107 will be explained.

[0084] In step S107, the determination unit 32 uses the third correlation information corresponding to the acquired temperature to determine the required operating time from the stop time read in step S101.

[0085] According to the fourth specific example of recovery control, the required operating time of the recovery mode is appropriately determined according to the stop time of the brush 72 and the temperature around the brush 72 during the period when the brush 72 is stopped. Therefore, creep is restored by implementing the recovery mode. As a result, the degradation of image quality caused by the brush 72 is suppressed.

[0086] <Fifth specific example of recovery control> As shown in Figure 4, when the radius of the brush 72 changes in a portion of it, the brightness of the toner image formed in the area of ​​the surface of the image carrier 1 that is in contact with that portion will differ from the brightness of the toner image formed in the remaining area. Therefore, as the brush 72 rotates, pitch unevenness with periodically fluctuating brightness may occur on the image transferred to the paper.

[0087] Figure 13 shows the relationship between the change in the radius of the brush ΔR and the amount of brightness variation (also called "pitch unevenness level") on the image formed using the image carrier in contact with the brush. As shown in Figure 13, the larger the change in ΔR, the larger the amount of brightness variation. However, if the amount of brightness variation is small, it is not visible to the human eye. In the example shown in Figure 13, pitch unevenness with a brightness variation of less than or equal to the reference value rv is not visible to humans. In Figure 13, the change in ΔR1 is the change in the radius of the brush 72 when the amount of brightness variation is equal to the reference value rv.

[0088] Figure 14 shows the brush stop time when the change in brush radius reaches ΔR1. Hereafter, the brush stop time when the change in brush radius reaches ΔR1 will be referred to as the "reference time". Figure 14 shows the same graph as Figure 9. In the example shown in Figure 14, the reference time when the ambient temperature around brush 72 is 20°C is 500 hours, and the reference time when the ambient temperature around brush 72 is 50°C is 100 hours.

[0089] If the stopping time of the brush 72 is less than or equal to the reference time, pitch unevenness caused by the creep of the brush 72 will not be visible to a human. Therefore, in order to shorten the actual operating time of the recovery mode, the determination unit 32 of the fifth specific example of recovery control only needs to determine the required operating time to be 0 if the stopping time of the brush 72 is less than or equal to the reference time.

[0090] In the fifth specific example of recovery control, the controller 22 has the functional configuration shown in Figure 3. The processing flow of the fifth specific example of recovery control is shown by the flowchart in Figure 7, similar to the first specific example. In addition, in the fifth specific example of recovery control, the processing flow of the subroutine in step S1 in Figure 7 follows one of the flowcharts in Figure 8 or Figures 10 to 12.

[0091] However, if the processing flow of the subroutine in step S1 follows the flowcharts in Figures 8 and 10, the decision unit 32 uses the second correlation information showing the relationship in Figure 15 instead of the second correlation information showing the relationship in Figure 6.

[0092] Figure 15 shows another example of the relationship between the change amount ΔR and the required operating time. The relationship shown in Figure 15 is determined in advance through experiments, etc. In Figure 15, the solid line 40a shows the required operating time when the rotational speed in recovery mode is the same as the rotational speed in normal mode. The solid line 42a shows the required operating time when the rotational speed in recovery mode is 1.1 times the rotational speed in normal mode. As shown in Figure 15, the solid lines 40a and 42a relate a change amount ΔR of ΔR less than or equal to ΔR1 to a required operating time of 0. Therefore, the determination unit 32 uses the second correlation information showing the relationship in Figure 15 to determine the required operating time to 0 when the change amount ΔR is less than or equal to ΔR1.

[0093] Furthermore, if the processing flow of the subroutine in step S1 follows the flowcharts in Figures 11 and 12, the decision unit 32 uses the third correlation information shown in Figure 16.

[0094] Figure 16 shows the relationship between the brush stop time and the required operating time for the recovery mode to recover from the creep caused by the stop time. The relationship shown in Figure 16 is determined in advance through experiments, etc. As shown in Figure 16, a brush stop time below the reference time is associated with an operating time of "0". Therefore, the determination unit 32 uses the third correlation information showing the relationship in Figure 16 to determine the operating time to be 0 when the stop time of the brush 72 is below the reference time.

[0095] <Sixth specific example of recovery control> In the fifth specific example described above, the determination unit 32 determines the required operating time to be 0 if the stop time of the brush 72 is less than or equal to the reference time, in order to shorten the actual operating time of the recovery mode. In contrast, in the sixth specific example of recovery control, the actual operating time of the recovery mode is shortened by setting the threshold Th1 used in step S5 to a value corresponding to the change amount ΔR1.

[0096] Figure 17 shows the time required to recover from the creep of a brush with a change of ΔR1. Figure 17 shows the same solid lines 40 and 42 as in Figure 6. As described above, solid line 40 shows the relationship between the change of ΔR and the time required to recover when the rotational speed in recovery mode is the same as the rotational speed in normal mode. Solid line 42 shows the relationship between the change of ΔR and the time required to recover when the rotational speed in recovery mode is 1.1 times the rotational speed in normal mode. In the example shown in Figure 17, the time required to recover from the creep of a brush with a change of ΔR1 is Th1a when the rotational speed in recovery mode is the same as the rotational speed in normal mode, and Th1b when the rotational speed in recovery mode is 1.1 times the rotational speed in normal mode.

[0097] The threshold Th1 used in step S5 is set to Th1a when the rotation speed in recovery mode is the same as the rotation speed in normal mode, and to Th1b when the rotation speed in recovery mode is 1.1 times the rotation speed in normal mode. As a result, when the rotation speed in recovery mode is the same as the rotation speed in normal mode, the operation of recovery mode ends when the remaining time indicated by the remaining time information 30b becomes less than or equal to Th1a (NO in step S5). Similarly, when the rotation speed in recovery mode is 1.1 times the rotation speed in normal mode, the operation of recovery mode ends when the remaining time indicated by the remaining time information 30b becomes less than or equal to Th1b (NO in step S5). This shortens the actual operating time of recovery mode.

[0098] If the remaining time falls below Th1a or Th1b, creep is restored until the change amount ΔR becomes ΔR1 or less. Therefore, pitch unevenness caused by brush 72 creep is not visible to the human eye. Consequently, even if the recovery mode ends when the remaining time is below Th1a or Th1b, there is virtually no impact on image quality.

[0099] <Seventh specific example of recovery control> In the seventh specific example of recovery control, the controller 22 also has the functional configuration shown in Figure 3. However, in the first specific example described above, the rotation control unit 33 controls the drive unit 75 to start the recovery mode operation in response to the main power supply of the image forming apparatus 101 being turned on. In contrast, in the seventh specific example of recovery control, the rotation control unit 33 controls the drive unit 75 to start the recovery mode operation in response to the receipt of a print instruction. As a result, the recovery mode is executed in parallel with the formation of an image on the image carrier 1.

[0100] Figure 18 is a flowchart showing the processing flow of the seventh specific example of recovery control. The flowchart in Figure 18 differs from the flowchart in Figure 7 in that it includes step S11, steps S12 and S13 between steps S4 and S5, and step S14 instead of step S7. Therefore, only steps S11 to S14 will be explained. Note that the flowchart in Figure 18 is executed in response to the receipt of a print instruction.

[0101] Step S11 is executed in parallel with steps S1 to S3. In step S11, the controller 22 starts printing (image formation) in response to the print instruction. Specifically, the controller 22 controls the image forming unit 26 in response to the print instruction.

[0102] In step S12, the controller 22 determines whether printing is complete or not. If printing is complete (YES in step S12), the rotation control unit 33 of the controller 22 controls the drive unit 75 to stop the rotation of the brush 72 (step S13). After step S13, the process ends. If printing is not complete (NO in step S12), the process moves to step S5.

[0103] If the answer in step S5 is NO, in step S14 the rotation control unit 33 controls the drive unit 75 to terminate the operation in recovery mode and start the operation in normal mode. As a result, the drive unit 75 rotates the brush 72 according to the normal mode. For example, if the rotation speeds in recovery mode and normal mode are different, the drive unit 75 changes the rotation speed of the brush 72 in step S14. After step S14, the process returns to step S12.

[0104] If step S5 is determined to be NO, it will also be determined to be NO in the next step S5. As a result, step S14 may be repeated multiple times. In the second and subsequent steps S14, the rotation control unit 33 only needs to control the drive unit 75 to continue in normal mode.

[0105] In the seventh specific example, the subroutine in step S1 may follow any of the flowcharts in Figures 8, 10 to 13. Furthermore, the fifth or sixth specific example may be applied to the seventh specific example.

[0106] According to the seventh specific example, the recovery mode is executed each time a print command is received. The required operating time of the recovery mode is determined according to the most recent stop time of the brush 72. This allows for creep recovery in parallel with image formation, and the deterioration of image quality caused by the brush 72 is suppressed as a result of the creep recovery.

[0107] <Eighth specific example of recovery control> In the seventh specific example described above, if the number of printed pages is small, the system may determine YES in step S12 before determining NO in step S5, and the recovery mode may be stopped in step S13. In this case, the recovery mode is executed for a shorter time than the time obtained by subtracting the threshold Th1 used in step S5 from the required operating time determined by the determination unit 32. Therefore, creep is not fully recovered. Accordingly, in the eighth specific example, the controller 22 adjusts the required operating time for the next recovery mode, taking into account the remaining time in the previous recovery mode.

[0108] Figure 19 is a block diagram showing another example of the controller's functional configuration. Figure 19 shows the configuration related to recovery control. The controller 22 shown in Figure 19 differs from the controller 22 shown in Figure 3 in that it includes a rotation control unit 33A instead of a rotation control unit 33, and also includes an adjustment unit 35.

[0109] In addition to the processing performed by the rotation control unit 33 described above, the rotation control unit 33A performs the following processing. Specifically, at the timing of ending the recovery mode, the rotation control unit 33A determines the remaining time indicated by the remaining time information 30b as the "previous remaining time". The rotation control unit 33A updates the previous remaining time information 30c stored in the storage unit 30 to indicate the "previous remaining time". As a result, the previous remaining time information 30c indicates the remaining time obtained by subtracting the actual operating time of the previous recovery mode from the required operating time determined for the previous recovery mode.

[0110] The adjustment unit 35 adjusts the required operating time determined by the determination unit 32 based on the previous remaining time indicated by the previous remaining time information 30c. In the eighth specific example, the determination unit 32 does not update the remaining time information 30b, but instead outputs the required operating time determined for the next recovery mode to the adjustment unit 35.

[0111] Specifically, the adjustment unit 35 updates the required operating time for the next recovery mode to the remaining time from the previous mode if the remaining time from the previous mode is longer than the required operating time from the next mode. Then, the adjustment unit 35 updates the remaining time information 30b stored in the storage unit 30 to indicate the adjusted required operating time.

[0112] On the other hand, the adjustment unit 35 does not adjust the required operating time for the next recovery mode if the operating time determined for the next recovery mode is greater than or equal to the remaining time from the previous mode. In other words, the adjustment unit 35 updates the remaining time information 30b stored in the storage unit 30 to indicate the operating time determined for the next recovery mode.

[0113] Figure 20 is a flowchart showing the first half of the processing flow of the eighth specific example of recovery control. Figure 21 is a flowchart showing the second half of the processing flow of the eighth specific example of recovery control. The flowcharts shown in Figures 20 and 21 differ from the flowchart shown in Figure 18 in that they include steps S21 to S23 between steps S1 and S2, and include step S24 after step S13 if the answer to step S12 is YES. Therefore, only steps S21 to S24 will be explained.

[0114] In step S21, the adjustment unit 35 of the controller 22 refers to the previous remaining time information 30c stored in the memory unit 30 and reads out the previous remaining time.

[0115] In the next step S22, the adjustment unit 35 determines whether the required operating time determined in step S1 (i.e., the required operating time determined for the next recovery mode) is equal to or greater than the remaining time from the previous step.

[0116] If the required operating time is greater than or equal to the remaining time from the previous step (YES in step S22), the process proceeds to step S2 without adjusting the required operating time. As a result, in step S2, the required operating time determined in step S1 is set as the remaining time. That is, the adjustment unit 35 updates the remaining time information 30b stored in the storage unit 30 to indicate the required operating time determined in step S1.

[0117] If the required operating time is not equal to or greater than the previous remaining time (NO in step S22), in step S23, the adjustment unit 35 updates the required operating time to the previous remaining time. After step S23, the process moves to step S2. As a result, in step S2, the adjustment unit 35 updates the remaining time information 30b stored in the storage unit 30 to indicate the adjusted required operating time (i.e., the previous remaining time).

[0118] In step S24, the rotation control unit 33A of the controller 22 determines the remaining time indicated by the remaining time information 30b as the "previous remaining time," and updates the previous remaining time information 30c stored in the storage unit 30 to indicate the "previous remaining time."

[0119] According to the eighth specific example, even if creep is not fully recovered due to a short operating time in the previous recovery mode, the required operating time for the next recovery mode is adjusted to take this insufficient operating time into account. Therefore, creep can be recovered by executing the next recovery mode.

[0120] <The ninth specific example of recovery control> The controller 22 in the ninth specific example adjusts the required operating time for the next recovery mode by considering the remaining time in the previous recovery mode as well as the rotation phase during the two most recent brush 72 stop periods.

[0121] Figure 22 is a block diagram showing yet another example of the controller's functional configuration. Figure 22 shows a configuration related to recovery control. The controller 22 shown in Figure 22 differs from the controller 22 shown in Figure 19 in that it includes a rotation control unit 33B instead of a rotation control unit 33A, and an adjustment unit 35A instead of an adjustment unit 35.

[0122] In addition to the processing performed by the rotation control unit 33A, the rotation control unit 33B performs the following processing. Specifically, each time the brush 72 is stopped, the rotation control unit 33B stores information indicating the rotation phase measured by the phase sensor 76 in the storage unit 30. The storage unit 30 stores first rotation phase information 30d and second rotation phase information 30e as information indicating the rotation phase. When the brush 72 is stopped, the rotation control unit 33B updates the second rotation phase information 30e to show the value of the rotation phase indicated by the first rotation phase information 30d, and also updates the first rotation phase information 30d to show the value of the rotation phase measured by the phase sensor 76. As a result, the first rotation phase information 30d shows the rotation phase detected by the phase sensor 76 at the most recent stop of the brush 72. The second rotation phase information 30e shows the rotation phase detected by the phase sensor 76 at the previous stop of the brush 72.

[0123] The adjustment unit 35A adjusts the required operating time determined by the determination unit 32 based on the previous remaining time indicated by the previous remaining time information 30c and the rotation phase indicated by the first rotation phase information 30d and the second rotation phase information 30e. In the ninth specific example, the determination unit 32 does not update the remaining time information 30b, but outputs the required operating time determined for the next recovery mode to the adjustment unit 35.

[0124] Specifically, the adjustment unit 35A determines whether the difference between the rotational phase indicated by the first rotational phase information 30d and the rotational phase indicated by the second rotational phase information 30e exceeds the threshold Th2.

[0125] If the difference exceeds the threshold Th2, the location of creep caused by the most recent stop in the brush 72 is different from the location of creep caused by the previous stop. In this case, similar to the eighth specific example, the required operating time for the next recovery mode is adjusted according to the comparison result between the creep situation caused by the most recent stop and the recovery situation of the creep caused by the previous stop. That is, the adjustment unit 35A adjusts the required operating time determined by the determination unit 32 based on the previous remaining time indicated by the previous remaining time information 30c.

[0126] Specifically, the adjustment unit 35A updates the required operating time for the next recovery mode to the remaining time from the previous mode if the remaining time from the previous mode is longer than the required operating time from the next mode. Then, the adjustment unit 35A updates the remaining time information 30b stored in the memory unit 30 to show the adjusted required operating time. On the other hand, the adjustment unit 35A does not adjust the required operating time for the next recovery mode if the required operating time from the next mode is greater than or equal to the remaining time from the previous mode. In other words, the adjustment unit 35A updates the remaining time information 30b stored in the memory unit 30 to show the required operating time from the next mode.

[0127] On the other hand, if the difference between the rotational phase indicated by the first rotational phase information 30d and the rotational phase indicated by the second rotational phase information 30e does not exceed the threshold Th2, the location of creep caused by the most recent stop and the location of creep caused by the previous stop in the brush 72 will overlap. In this case, if the creep recovery by the execution of the previous recovery mode is insufficient, the radius of the brush 72 may change by a larger amount than the change in the radius of the brush 72 ΔR estimated from the most recent stop time. Therefore, the creep cannot be sufficiently recovered by the operation time determined for the next recovery mode alone. Thus, the adjustment unit 35A increases the operation time determined for the next recovery mode by the remaining time from the previous mode. Then, the adjustment unit 35A updates the remaining time information 30b stored in the storage unit 30 to indicate the operation time after the adjustment.

[0128] Figure 23 is a flowchart showing the first half of the processing flow of the ninth specific example of recovery control. Figure 24 is a flowchart showing the second half of the processing flow of the ninth specific example of recovery control. The flowcharts shown in Figures 23 and 24 differ from those shown in Figures 20 and 21 in that they include steps S31 to S33 instead of step S21, and step S34 after step S24. Therefore, only steps S31 to S24 will be explained.

[0129] In step S31, the adjustment unit 35A of the controller 22 refers to the previous remaining time information 30c stored in the memory unit 30 and reads out the previous remaining time. Furthermore, the adjustment unit 35A refers to the first rotation phase information 30d and the second rotation phase information 30e stored in the memory unit 30 and reads out the rotation phase of the brush 72 at the most recent stop and the rotation phase of the brush 72 at the previous stop.

[0130] In the next step S32, the adjustment unit 35A determines whether the difference between the rotational phase of the brush 72 at the most recent stop and the rotational phase of the brush 72 at the previous stop exceeds the threshold Th2.

[0131] If the difference in rotational phase does not exceed the threshold Th2 (NO in step S32), in step S33, the adjustment unit 35A increases the required operating time by the remaining time from the previous step. After step S33, the process moves to step S2. As a result, in step S2, the adjustment unit 35A updates the remaining time information 30b stored in the storage unit 30 to indicate the required operating time after adjustment.

[0132] If the difference in rotational phase exceeds the threshold Th2 (YES in step S32), the process proceeds to step S22.

[0133] In step S34, the rotation control unit 33B of the controller 22 updates the second rotation phase information 30e with the latest rotation phase at the time of stopping read in step S31 as the rotation phase at the time of previous stopping. Specifically, the rotation control unit 33A updates the second rotation phase information 30e to show the value of the rotation phase indicated by the first rotation phase information 30d. Furthermore, the rotation control unit 33A updates the first rotation phase information 30d with the measurement result of the phase sensor 76 as the latest rotation phase at the time of stopping. Specifically, the rotation control unit 33A obtains the value of the rotation phase measured by the phase sensor 76 and updates the first rotation phase information 30d to show that value.

[0134] According to the ninth specific example, if the difference between the rotation phase of brush 72 at the time of the previous stop and the rotation phase of brush 72 at the time of the most recent stop does not exceed the threshold Th2, the required operating time for the next recovery mode is adjusted to be longer by the remaining time from the previous stop. This ensures that even if the creep recovery by the previous recovery mode was insufficient, the creep can be recovered by running the next recovery mode for the required operating time.

[0135] (modified version) The image forming apparatus 101 may be equipped with a cleaning device including a cleaning brush instead of the cleaning device 7 which includes the brush 72. The cleaning brush rotates relative to the image carrier 1, collecting and retaining residual toner adhering to the surface of the image carrier 1. In this case, the controller 22 can perform the recovery control described above for the cleaning brush instead of the brush 72.

[0136] (Note) As described above, this embodiment includes the following disclosures.

[0137] <Configuration 1> An image forming apparatus, Image carrier and, A brush that contacts the image carrier, The image forming apparatus further comprises a drive unit for rotating the brush, the drive unit having a recovery mode for rotating the brush to recover from creep that occurs when the brush is stopped, and the image forming apparatus further comprises An image forming apparatus comprising a determination unit that determines the required operating time of the recovery mode according to the amount of change in the radius of the brush due to the creep.

[0138] <Configuration 2> The image forming apparatus according to configuration 1, wherein the determination unit estimates the amount of change from the stopping time of the brush.

[0139] <Structure 3> The image forming apparatus according to configuration 1, wherein the determination unit estimates the amount of change from the stopping time of the brush and the temperature around the brush during the period when the brush is stopped.

[0140] <Structure 4> The image forming apparatus according to configuration 1, wherein the determination unit determines the required operating time based on the stopping time of the brush which correlates with the amount of change.

[0141] <Composition 5> The image forming apparatus according to configuration 1, wherein the determination unit determines the required operating time based on the stopping time of the brush and the temperature around the brush during the period when the brush is stopped, which are correlated with the amount of change.

[0142] <Composition 6> The drive unit has a normal mode, separate from the recovery mode, in which it rotates the brush when an image is formed on the image carrier. The image forming apparatus according to any one of configurations 1 to 5, wherein the rotation speed in the recovery mode is faster than the rotation speed in the normal mode.

[0143] <Composition 7> The recovery mode is performed before the formation of an image on the image carrier, according to any one of the configurations 1 to 6 of the image forming apparatus.

[0144] <Structure 8> The recovery mode is performed in parallel with the formation of an image on the image carrier, as described in any of configurations 1 to 6 of the image forming apparatus.

[0145] <Composition 9> A storage unit that stores the remaining time obtained by subtracting the actual operating time of the previous recovery mode from the operating time determined for the previous recovery mode, The system further includes an adjustment unit for adjusting the required operating time, The image forming apparatus according to any one of configurations 1 to 6 and 8, wherein the adjustment unit updates the required operating time determined for the next recovery mode to the remaining time if the remaining time is longer than the required operating time determined for the next recovery mode.

[0146] <Composition 10> A sensor for detecting the rotational phase of the brush, A storage unit that stores the remaining time obtained by subtracting the actual operating time of the previous recovery mode from the operating time required for the previous recovery mode determined for the previous recovery mode, the first rotation phase detected by the sensor at the most recent stop of the brush, and the second rotation phase detected by the sensor at the previous stop of the brush. The system further includes an adjustment unit for adjusting the required operating time, The image forming apparatus according to any one of configurations 1 to 6 and 8, wherein the adjustment unit updates the required operating time determined for the next recovery mode to the remaining time when the difference between the first rotation phase and the second rotation phase exceeds a threshold and the remaining time is longer than the required operating time determined for the next recovery mode.

[0147] <Composition 11> The image forming apparatus according to configuration 10, wherein the adjustment unit increases the required operating time determined for the next recovery mode by the remaining time, depending on whether the difference is less than or equal to the threshold.

[0148] <Composition 12> The image forming apparatus according to any one of configurations 1 to 11, wherein the brush applies a lubricant to the image carrier.

[0149] <Composition 13> A method for using a brush that comes into contact with the image carrier of an image forming apparatus, The steps include: executing a recovery mode in which the brush is rotated to recover from the creep that occurs while the brush is stopped; A method of use comprising the step of determining the required operating time of the recovery mode according to the amount of change in the radius of the brush due to the creep.

[0150] The embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. The scope of the present invention is indicated by the claims rather than by the foregoing description, and all modifications within the meaning and scope equivalent to the claims are intended. [Explanation of Symbols]

[0151] 1 Image carrier, 2 Charging device, 3 Exposure device, 4 Developing device, 5 Primary transfer roller, 7 Cleaning device, 8 Contact part, 10 Image forming unit, 12 Intermediate transfer belt, 14 Transfer part, 16 Fixing device, 18 Temperature sensor, 22 Controller, 23 Operation display unit, 24 Image input unit, 25 Transport unit, 26 Image forming unit, 28 Paper feeding unit, 29 Paper output tray, 30 Storage unit, 30a Stop time information, 30b Remaining time information, 30c Previous remaining time information, 30d First rotation phase information, 30e Second rotation phase information, 31 Stop time measurement unit, 32 Determination unit, 33, 33A, 33B Rotation control unit, 34 Counter, 35, 35A Adjustment unit, 71 Cleaning blade, 72 Brush, 72a Shaft, 73 Solid lubricant, 74 Fixed blade, 75 Drive unit, 76 phase sensor, 101 image forming apparatus, 221 processor, 222 memory, 223 storage.

Claims

1. An image forming apparatus, Image carrier and, A brush that contacts the image carrier, The unit comprises a drive unit for rotating the brush, The drive unit is capable of executing a recovery mode in which it rotates the brush in order to recover from the creep that occurs when the brush is stopped. Furthermore, the determination unit determines that the greater the change in the radius of the brush due to the creep, the greater the required operating time for the recovery mode. An adjustment unit updates the required operating time for the next recovery mode to the remaining time if the required operating time for the next recovery mode is less than the remaining time obtained by subtracting the actual operating time of the previous recovery mode from the required operating time for the previous recovery mode. An image forming apparatus comprising:

2. The image forming apparatus according to claim 1, wherein the determination unit estimates the amount of change from the stopping time of the brush.

3. The image forming apparatus according to claim 1, wherein the determination unit estimates the amount of change from the stopping time of the brush and the temperature around the brush during the period when the brush is stopped.

4. The image forming apparatus according to claim 1, wherein the determination unit determines the required operating time based on the stopping time of the brush which correlates with the amount of change.

5. The image forming apparatus according to claim 1, wherein the determination unit determines the required operating time based on the stopping time of the brush and the temperature around the brush during the period in which the brush is stopped, which are correlated with the amount of change.

6. The drive unit has a normal mode, separate from the recovery mode, in which it rotates the brush when an image is formed on the image carrier. The image forming apparatus according to any one of claims 1 to 5, wherein the rotation speed in the recovery mode is faster than the rotation speed in the normal mode.

7. The image forming apparatus according to any one of claims 1 to 5, wherein the recovery mode is performed before the formation of an image on the image carrier.

8. The image forming apparatus according to any one of claims 1 to 5, wherein the recovery mode is performed in parallel with the formation of an image on the image carrier.

9. The image forming apparatus according to any one of claims 1 to 5, further comprising a storage unit for storing the remaining time.

10. An image forming apparatus, Image carrier and, A brush that contacts the image carrier, The unit comprises a drive unit for rotating the brush, The drive unit is capable of executing a recovery mode in which it rotates the brush in order to recover from the creep that occurs when the brush is stopped. Furthermore, the determination unit determines that the greater the change in the radius of the brush due to the creep, the greater the required operating time for the recovery mode. A sensor for detecting the rotational phase of the brush, An adjustment unit updates the required operating time for the next recovery mode to the remaining time if the difference between the first rotational phase detected by the sensor at the most recent stop of the brush and the second rotational phase detected by the sensor at the previous stop of the brush exceeds a threshold, and the remaining time obtained by subtracting the actual operating time of the previous recovery mode from the required operating time for the previous recovery mode is longer than the required operating time for the next recovery mode determined for the next recovery mode. An image forming apparatus comprising:

11. The image forming apparatus according to claim 10, wherein the adjustment unit increases the required operating time determined for the next recovery mode by the remaining time, depending on whether the difference is less than or equal to the threshold.

12. The image forming apparatus according to claim 10 or 11, further comprising a storage unit for storing the remaining time, the first rotation phase, and the second rotation phase.

13. The image forming apparatus according to any one of claims 1 to 5 and 10 and 11, wherein the brush applies a lubricant to the image carrier.

14. A method for using a brush that comes into contact with the image carrier of an image forming apparatus, The steps include: executing a recovery mode in which the brush is rotated to recover from the creep that occurs while the brush is stopped; The steps include determining that the required operating time for the recovery mode will be larger the greater the amount of change in the radius of the brush due to the creep, If the required operating time determined for the next recovery mode is less than the remaining time obtained by subtracting the actual operating time of the previous recovery mode from the required operating time determined for the previous recovery mode, the required operating time determined for the next recovery mode is updated to the remaining time. Instructions for use, including the provision of such instructions.

15. A method for using a brush that comes into contact with an image carrier in an image forming apparatus, The steps include: executing a recovery mode in which the brush is rotated to recover from the creep that occurs while the brush is stopped; The steps include determining that the required operating time for the recovery mode will be larger the greater the amount of change in the radius of the brush due to the creep, The steps include updating the required operation time for the next recovery mode to the remaining time, depending on whether the difference between the first rotation phase detected by the sensor that detects the rotation phase of the brush at the most recent stop of the brush and the second rotation phase detected by the sensor at the previous stop of the brush exceeds a threshold, and whether the remaining time obtained by subtracting the actual operating time of the previous recovery mode from the required operation time determined for the previous recovery mode is longer than the required operation time determined for the next recovery mode; Instructions for use, including the provision of such instructions.

Images