Image forming apparatus, control method, and control program

Abstract

The photoreceptor is driven appropriately. [Solution] The image forming apparatus 1 comprises a photoreceptor 32, a drive motor 37 capable of rotating the photoreceptor 32, and a control unit 97. The control unit 97 detects the rotational torque of the photoreceptor 32 and determines whether the rotational torque is greater than a first threshold Th1. If the control unit 97 determines that the rotational torque is greater than the first threshold Th1, it performs torque reduction control to reduce the rotational torque.

Description

Technical Field

[0005] , , , ,

[0001] The present invention relates to an image forming apparatus, a control method, and a control program.

Background Art

[0002] Conventionally, for example, as an image forming apparatus using an electrophotographic method, a tandem type is known. In a tandem type image forming apparatus, a color image is formed by transferring a toner image onto a sheet from a drum-shaped photoreceptor (image carrier) corresponding to each color toner (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The photoreceptor is connected to a drive motor via a coupling. Therefore, if the rotational torque of the photoreceptor becomes excessively high, an excessive load is applied to the connection part with the drive motor, and the coupling may be damaged. If the coupling is damaged, the photoreceptor cannot be driven properly, and problems may occur in image formation. The present invention has been made in view of the above circumstances, and an object thereof is to drive the photoreceptor appropriately.

Means for Solving the Problems

[0005] To achieve the above object, the present invention provides an image forming apparatus, comprising: an image carrier; a drive unit capable of rotationally driving the image carrier; a detection unit that detects the rotational torque of the image carrier; a determination unit that determines whether the rotational torque is greater than a threshold value; If the determination unit determines that the rotational torque is greater than the threshold, the torque control unit executes torque reduction control to reduce the rotational torque. It is equipped with. [Effects of the Invention]

[0006] According to the present invention, if it is determined that the rotational torque of the image carrier is greater than a threshold, torque reduction control is performed to reduce the rotational torque. This allows the photoreceptor to be driven effectively. [Brief explanation of the drawing]

[0007] [Figure 1] This figure shows a schematic configuration of an image forming apparatus according to an embodiment. [Figure 2] This is a cross-sectional view of a photoreceptor unit according to an embodiment. [Figure 3] This is a block diagram showing a schematic control configuration of an image forming apparatus according to an embodiment. [Figure 4] This flowchart shows the flow of the torque control process according to the embodiment. [Figure 5] This figure shows an example of the waveform of the rotational torque of the photoreceptor. [Figure 6] This figure shows examples of waveforms of the rotational torque of the photoreceptor when each part undergoes changes over time. [Figure 7] This figure shows an example of the waveform of the rotational torque of the photoreceptor when the time axis scale is set to a long period of time. [Figure 8] This is a diagram illustrating the torque reduction control according to the embodiment. [Figure 9] This figure illustrates the effects of the torque control process according to the embodiment. [Figure 10] This flowchart shows the flow of the torque control process according to modified embodiment 1. [Figure 11] This is a diagram illustrating torque reduction control according to a modified example 1 of the embodiment. [Modes for carrying out the invention]

[0008] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0009] [Overall Configuration of Image Forming Apparatus] FIG. 1 is a diagram showing a schematic configuration of an image forming apparatus 1 according to the present embodiment. As shown in this figure, the image forming apparatus 1 according to the present embodiment forms an image on a sheet S, for example, by an electrophotographic method. Specifically, the image forming apparatus 1 includes an image reading unit 2, an image forming unit 3, an intermediate transfer unit 4, a paper feeding unit 51, a paper conveyance unit 55, a secondary transfer unit 6, and a fixing unit 7.

[0010] The image reading unit 2 reads a document with scanning exposure means 21 and outputs an image information signal (image data). That is, the document placed on the document table 22 is scanned and exposed to light by the optical system constituting the scanning exposure means 21 and read into the line image sensor.

[0011] The image forming unit 3 includes five image forming parts 31 that form toner images of different colors. The five image forming parts 31 form toner images of each color of yellow (Y), magenta (M), cyan (C), black (K), and special color (Z) (for example, white (W)) in order from the upper side of FIG. 1. Each image forming part 31 forms a toner image of each color on the photoreceptor 32 and primarily transfers the toner image to the intermediate transfer belt 41. Each image forming part 31 includes a photoreceptor 32, a charging device 33, an exposure device 34, a developing device 35, and a cleaning unit 80.

[0012] The photoreceptor 32 is a drum-shaped image carrier that carries an image (toner image) on its surface. The photoreceptor 32 is composed of an organic photoreceptor in which a photosensitive layer made of a resin containing an organic photoconductor is formed on the outer peripheral surface of a drum-shaped metal substrate, and is rotationally driven in a predetermined rotational direction R (counterclockwise in the figure). The photoreceptor 32 constitutes a photoreceptor unit 32U together with the cleaning unit 80 and the like, as will be described later.

[0013] The charging device 33 uniformly charges the surface of the photoreceptor 32 to a certain potential. The exposure device 34 exposes the non-image area of the photoreceptor 32 based on the image data from the image reading unit 2, and forms an electrostatic latent image on the image area of the photoreceptor 32. Note that the image data is not limited to the data output from the image reading unit 2, and may be received from an external device such as a client terminal, for example. The developing device 35 has a developing roller 352 (see FIG. 2) facing the photoreceptor 32. The developing roller 352 carries the supplied developer and supplies the toner contained in the carried developer to the photoreceptor 32. By supplying toner onto the electrostatic latent image formed on the photoreceptor 32, a toner image is formed on the photoreceptor 32. The cleaning unit 80 is disposed below the photoreceptor 32, and removes the toner remaining on the surface of the photoreceptor 32, for example, by a blade method.

[0014] The intermediate transfer unit 4 includes an intermediate transfer belt 41 and a primary transfer roller 42. The intermediate transfer belt 41 is a belt-like image carrier stretched over a plurality of rollers, which carries an image (toner image) on its surface and conveys it in the moving direction T. The primary transfer roller 42 is disposed to face each photoreceptor 32 with the intermediate transfer belt 41 interposed therebetween. The primary transfer roller 42 presses the intermediate transfer belt 41 against each opposing photoreceptor 32, and primarily transfers the toner image formed on the photoreceptor 32 to the intermediate transfer belt 41.

[0015] The paper feeding unit 51 includes a plurality of trays 52 for accommodating sheets S as recording media. Different sheets S such as different sizes, paper qualities, and paper types are accommodated in the plurality of trays 52. The sheet S is sent out onto the conveyance path of the paper conveyance unit 55 from the paper feeding unit 51. The paper conveyance unit 55 has a plurality of rollers 56 and conveys the sheet S sent out from the paper feeding unit 51. The sheet S supplied from the tray 52 of the paper feeding unit 51 is conveyed to the secondary transfer unit 6 via the registration roller 57.

[0016] The secondary transfer unit 6 has a secondary transfer roller 61. The secondary transfer roller 61 brings the paper S, which has been transported by the paper transport unit 55, into contact with the intermediate transfer belt 41, and secondary transfers the toner image supported on the surface of the intermediate transfer belt 41 to the paper S. The fixing unit 7 is located downstream (discharge side) of the paper S in the transport direction from the secondary transfer unit 6. The fixing unit 7 heats and pressurizes the transported paper S to fix the toner image transferred to the paper S.

[0017] [Overall structure of the photoconductor unit] Figure 2 is a cross-sectional view of the photoreceptor unit 32U. As shown in this figure, the photoreceptor unit 32U is a unitized assembly of the photoreceptor 32 and the cleaning unit 80, etc. The photoreceptor 32 is driven by a drive motor 37 (see Figure 3). The photoreceptor 32 and the drive motor 37 are connected by a resin coupling 38 (see Figure 3).

[0018] The cleaning unit 80 includes a cleaning blade 81 and an application brush 82. The cleaning blade 81 is an elastic member formed from urethane rubber or the like into a flat plate shape, and has a length approximately equal to the longitudinal length of the photoreceptor 32. During image formation, the cleaning blade 81 is positioned in contact with the surface of the photoreceptor 32 in a direction counter to the rotational direction R. As the photoreceptor 32 rotates, the cleaning blade 81 scrapes off any remaining transfer toner on the surface of the photoreceptor 32. The scraped-off transfer toner is collected by the recovery screw 811 into a waste toner box (not shown).

[0019] The coating brush 82 is in contact with the photoreceptor 32 downstream of the cleaning blade 81 in the rotational direction R. The coating brush 82 is also in contact with a lubricant 83, which is a solidified lubricant such as zinc stearate (ZnSt). As the coating brush 82 rotates, it scrapes the lubricant from the surface of the lubricant 83 and applies it to the surface of the photoreceptor 32.

[0020] Figure 3 is a block diagram showing the schematic control configuration of the image forming apparatus 1. As shown in this figure, in addition to the above-mentioned parts, the image forming apparatus 1 includes an operation unit 91, a display unit 92, a communication unit 94, a storage unit 96, and a control unit 97.

[0021] The operation unit 91 is an operating means that allows the user (operator) to perform various operations to operate the image forming apparatus 1, and outputs an operation signal corresponding to the operation to the control unit 97. The display unit 92 is, for example, a liquid crystal display, an organic electroluminescent display, or other type of display. The display unit 92 displays various information based on display signals from the control unit 97. The display unit 92 may also be a touchscreen that also functions as at least a part of the operation unit 91. The communication unit 94 connects to external devices, such as a PC, via a network to enable communication and transmit and receive various types of data, such as image data and job data.

[0022] The memory unit 96 is a memory composed of, for example, RAM (Random Access Memory) or ROM (Read Only Memory). The memory unit 96 stores various programs and data, including the program that executes the torque control processing described later, and also functions as a work area for the control unit 97. The control unit 97 is composed of, for example, a CPU (Central Processing Unit) and controls the operation of each part of the image forming apparatus 1. Based on the operation content of the operation unit 91, the control unit 97 loads a program pre-stored in the storage unit 96 and performs various processes in cooperation with the loaded program.

[0023] [Torque control of the photoreceptor] Next, we will explain the torque control process for controlling the rotational torque of the photoreceptor 32. Figure 4 is a flowchart showing the flow of the torque control process. Figures 5 to 9 are diagrams illustrating the torque control process.

[0024] Torque control processing is a process that controls the rotational torque of the photoreceptor 32 during image formation. This torque control processing is performed by the control unit 97 reading the relevant program from the storage unit 96 and loading it. This program may be part of the image formation program that is executed when forming an image on the paper S.

[0025] As shown in Figure 4, in the torque control process, first, when the control unit 97 receives a print job based on user operation (step S1), it starts driving the photoreceptor 32 at a normal speed (step S2). Here, the "normal" speed of the photoreceptor 32 refers to a predetermined reference speed that has been set in advance. Here, the control unit 97 controls the drive motor 37 to rotate the photoreceptor 32.

[0026] Next, when an image corresponding to the print job is formed on the paper S (step S3), the control unit 97 detects the rotational torque (driving torque) of the photoreceptor 32 (step S4). Here, the control unit 97 detects the rotational torque of the photoreceptor 32 based on, for example, the current value of the drive motor 37. However, the parameter used here does not have to be the current value of the drive motor 37, as long as it is a parameter correlated with the rotational torque of the photoreceptor 32; for example, it could be the measured rotational torque.

[0027] Here, we will explain the change in rotational torque of the photoreceptor 32 during image formation. As shown in Figure 5, the rotational torque of the photoreceptor 32 during image formation changes, for example, in a rectangular wave shape, depending on the job. This rotational torque may have a whisker-like pulse P superimposed on it at the start of the photoreceptor 32's drive, causing it to rise sharply momentarily. This pulse P is caused by the cleaning blade 81 being pulled into the rotation of the photoreceptor 32 and then immediately returning to its original position due to its own elasticity, etc. Furthermore, as shown in Figure 6, the torque value when driving the photoreceptor 32 gradually increases from the initial value (shown by the dashed line) over time due to the aging of each part. In other words, when the time axis scale is set to a long period (for example, several months), the rotational torque changes as shown in Figure 7. When these torque-increasing factors combine and the rotational torque exceeds a certain second threshold Th2, the resin coupling 38 connecting the photoreceptor 32 and the drive motor 37 is damaged. The coupling 38 is provided at the connection point between the photoreceptor 32 and the drive motor 37 and is screwed into a metal shaft fixed to the photoreceptor 32. Therefore, when the rotational torque of the photoreceptor 32 exceeds a predetermined second threshold Th2, the screw threads of the coupling 38 screwed into the metal shaft may break, potentially damaging the coupling 38.

[0028] The phenomenon described above, in which the cleaning blade 81 is drawn into the photoreceptor 32, is more likely to occur depending on the properties of the toner. For example, in the case of toner with a small amount of external additives, the coefficient of friction between the cleaning blade 81 and the photoreceptor 32 increases. External additives are fine particles added to the toner, which is a colorant, for the purpose of imparting properties such as electrostatic charge, fluidity, and lubricity. When the coefficient of friction between the cleaning blade 81 and the photoreceptor 32 increases, the number of times the cleaning blade 81 is drawn into and released by the photoreceptor 32 increases. As a result, the load caused by this load fluctuation accumulates in the coupling 38, leading to damage to the coupling 38 in the form of fatigue failure.

[0029] Therefore, in this embodiment, the rotational torque of the photoreceptor 32 is monitored, and torque reduction control is performed to reduce the rotational torque as needed. Specifically, the control unit 97 determines whether the rotational torque detected in step S4 is greater than the first threshold Th1 (step S5). Here, the first threshold Th1 is a torque value that is given a predetermined margin over the second threshold Th2 mentioned above, and is not particularly limited, but for example, it is 60-80% of the second threshold Th2. If, in step S5, it is determined that the rotational torque is not greater than the first threshold Th1 (step S5; No), the control unit 97 proceeds to step S7, which will be described later.

[0030] On the other hand, if in step S5 it is determined that the rotational torque is greater than the first threshold Th1 (step S5; Yes), the control unit 97 performs torque reduction control (step S6). Here, the control unit 97 performs at least one of the following eight operations as torque reduction control.

[0031] Action 1: Reduce the drive speed of the photoreceptor 32 to a lower speed than normal. Operation 2: Toner is supplied from the developing device 35 to the photoreceptor 32. Action 3: Increase the toner density in the developing device 35. Operation 4: Reduce the voltage applied to the developing roller 352 when not forming an image. Operation 5: Lower the surface potential of the photoreceptor 32 when not forming an image. Operation 6: Change the output of the primary transfer roller 42 that contacts the photoreceptor 32. Operation 7: Change the position of the primary transfer roller 42 that is in contact with the photoreceptor 32. Operation 8: Reduce the contact force of the cleaning blade 81 that contacts the photoreceptor 32.

[0032] Specifically, in operation 1, the control unit 97 controls the drive motor 37 to lower the driving speed of the photoreceptor 32 compared to normal operation. In operation 2, the control unit 97 supplies toner from the developing device 35 to the photoreceptor 32 by printing toner patches between images. In this case, the toner patch is a band-shaped print that extends along the longitudinal direction of the photoreceptor 32, so that toner is supplied widely in the longitudinal direction. More toner may be printed in areas with less coverage in the longitudinal direction. In operation 3, the control unit 97 increases the toner concentration in the developing device 35 by controlling the developing device 35. Here, for example, the toner concentration is increased by setting a target concentration value that is a predetermined value higher than the actual toner concentration detected by the concentration sensor. In operation 4, the control unit 97 controls the developing device 35 to reduce the voltage applied to the developing roller 352 when no image is being formed. In operation 5, the control unit 97 detects the surface potential of the photoreceptor 32 during non-image formation based on a drum potential sensor (not shown) and reduces it. In operation 6, the control unit 97 changes the output of the primary transfer roller 42 that contacts the photoreceptor 32 by controlling the primary transfer roller 42. In this operation, the output of the primary transfer roller 42 may be increased or decreased. In operation 7, the control unit 97 changes the position of the primary transfer roller 42 that contacts the photoreceptor 32 by controlling the primary transfer roller 42. In operation 8, the control unit 97 reduces the contact force of the cleaning blade 81 against the photoreceptor 32 by controlling the cleaning unit 80. The specific means for reducing the contact force of the cleaning blade 81 are not particularly limited. For example, the cleaning blade 81 may be configured to be rotatable with the end opposite to the photoreceptor 32 as its base end, and this rotation may be driven by a motor, with the output of the motor being controlled.

[0033] Operations 1 to 8 can be broadly categorized into three types based on their control content: operation control of the photoreceptor 32, toner supply control, and pressure control of the cleaning blade 81. Operation 1 controls the operation of the photoreceptor 32, operations 2 to 7 control the toner supply, and operation 8 controls the pressure of the cleaning blade 81. Of the toner supply controls (operations 2 to 7), operations 3 to 5 are for increasing the amount of toner that flies onto the photoreceptor 32, while operations 6 and 7 are for increasing the amount of toner supplied to the photoreceptor 32 by increasing the amount of toner remaining after the primary transfer. Furthermore, among operations 1-8, operations 1 and 8 experience a more rapid decrease in rotational torque compared to the other operations.

[0034] In this embodiment, as shown in Figure 8, the control unit 97 performs torque reduction control at the last timing of the job in which a rotational torque greater than the first threshold Th1 is detected. Figure 8 is an example of a torque waveform when printing a toner patch in operation 2. The control unit 97 performs torque reduction control at the last timing of the job (the second job in Figure 8), when the rotational torque should normally be reduced, before stopping the drive of the photoreceptor 32.

[0035] Next, the control unit 97 stops the driving of the photoreceptor 32 (step S7), and then terminates the job (step S8). The control unit 97 repeats the above process for each job.

[0036] [Technical effects of this embodiment] As described above, according to this embodiment, if it is determined that the rotational torque of the photoreceptor 32 (image carrier) is greater than the first threshold Th1, torque reduction control is performed to reduce the rotational torque. This reduces the load on the coupling 38 connecting the photoreceptor 32 and the drive motor 37. Consequently, as shown in Figure 9, the time until the coupling 38 is damaged (broken) can be extended. Furthermore, the possibility of damage to the coupling 38 can be recognized in advance, allowing countermeasures such as replacing the toner bottle to be taken. Therefore, the photoreceptor 32 can be driven effectively.

[0037] Furthermore, according to this embodiment, torque reduction control is executed at the final timing of the job. In other words, since the control is executed at the time the job is completed, there is no delay in the job caused by the control. Therefore, torque reduction control can be performed effectively without causing dissatisfaction to the user.

[0038] [Example 1] In the above embodiment, torque reduction control was performed at the last timing of the job in which a rotational torque greater than the first threshold Th1 was detected. However, the timing of performing torque reduction control may also be at the beginning of the next job in which excessive torque is detected. Specifically, in this case, as shown in Figure 10, the control unit 97 first accepts a print job based on, for example, user operation (step T1).

[0039] Next, the control unit 97 determines whether or not the rotational torque of the photoreceptor 32 was determined to be greater than the first threshold Th1 during the immediately preceding job execution (step T2). If it determines that the rotational torque of the photoreceptor 32 was not greater than the first threshold Th1 during the immediately preceding job execution (step T2; No), the control unit 97 proceeds to step T5, which will be described later.

[0040] In step T2, if it is determined that the rotational torque of the photoreceptor 32 was greater than the first threshold Th1 during the previous job execution (step T2; Yes), the control unit 97 starts driving the photoreceptor 32 at a slower speed than normal (step T3). This is to prevent damage to the coupling 38 before applying a toner patch, for example, when applying a toner patch at the beginning of a job as shown in Figure 11. Then, the control unit 97 performs torque reduction control (step T4) in the same manner as in step S6 of the above-described embodiment. However, in this case, it is preferable to perform operation 1 or operation 8, which rapidly reduces the rotational torque.

[0041] Next, the control unit 97 controls the drive motor 37 to drive the photoreceptor 32 at a preset normal speed (step T5). Next, when an image corresponding to the print job is formed on the paper S (step T6), the control unit 97 detects the rotational torque (driving torque) of the photoreceptor 32 (step T7).

[0042] Then, the control unit 97 stops the driving of the photoreceptor 32 (step T8) and then terminates the job (step T9). As described above, even when torque reduction control is performed at the first timing of the next job after excessive torque is detected, the same effects as in the above embodiment can be obtained.

[0043] [Differentiation 2] In the above embodiment, torque reduction control is performed when the rotational torque of the photoreceptor 32 exceeds the first threshold Th1 (threshold) at least once. However, the timing at which torque reduction control is performed when it is determined that the rotational torque is excessive is not limited to this. For example, it may be determined that the rotational torque is greater than the threshold when the rotational torque exceeds the threshold at least once, when the rotational torque exceeds the threshold a predetermined number of times, or when the time integral value of the rotational torque that exceeds the threshold exceeds a predetermined value.

[0044] [Difference 3] In the above embodiment, torque reduction control was performed only once when it was determined that the rotational torque of the photoreceptor 32 was excessive. However, torque reduction control may be performed a number of times corresponding to the detected rotational torque. Specifically, if the detected rotational torque exceeds the first threshold Th1, the number of times torque reduction control is performed may be increased as the excess rotational torque increases.

[0045] [Differentiation Example 4] If the detected rotational torque is determined to be greater than the first threshold Th1, the system may perform torque reduction control and also notify that the rotational torque of the photoreceptor 32 is excessive. The notification method in this case is not particularly limited; for example, the system may display that the torque of the photoreceptor 32 is excessive on the display unit 92, or it may notify a service technician or user of this fact via the communication unit 94, or both may be performed. This allows a service technician or user who recognizes excessive torque on the photoreceptor 32 to address the situation appropriately before the coupling 38 is damaged. In this case, it is preferable to replace the toner (toner bottle) suspected to be the cause with an appropriate one, rather than replacing the coupling 38 or the photoreceptor 32.

[0046] [others] Although one embodiment of the present invention has been described above, the embodiments to which the present invention can be applied are not limited to the embodiments and their modifications described above, and can be modified as appropriate without departing from the spirit of the present invention.

[0047] For example, the first threshold Th1, which is compared with the detected rotational torque, does not have to be constant. For example, the first threshold Th1 may be changed depending on the durability of the photoreceptor unit 32U, the durability of the developing device 35, or the type of toner used. [Explanation of symbols]

[0048] 1. Image forming apparatus 32 Photoreceptor (Image Carrier) 35. Developing device 352 Developing Roller 37. Drive motor (drive unit) 38 Coupling 42 Primary transfer roller 80 Cleaning Department 81 Cleaning Blade 92 Display Unit (Notification Unit) 94 Communications Department (News Department) 97 Control Unit (Detection Unit, Determination Unit, Torque Control Unit) S paper Th1 First threshold (threshold)

Claims

1. Image carrier and, A drive unit capable of rotating the image carrier, A detection unit for detecting the rotational torque of the image carrier, A determination unit that determines whether the rotational torque is greater than a threshold, If the determination unit determines that the rotational torque is greater than the threshold, the torque control unit executes torque reduction control to reduce the rotational torque. An image forming apparatus equipped with the following features.

2. The torque control unit is The last timing in driving the image carrier when the rotational torque is determined to be greater than the threshold, Alternatively, when it is determined that the rotational torque is greater than the threshold, at the first timing of the next drive of the image carrier, The torque reduction control described above is performed by The image forming apparatus according to claim 1.

3. The torque reduction control includes at least one of the following: control of the movement of the image carrier, control of the supply of toner to the image carrier, and control of the pressing force of the cleaning member that contacts the image carrier. The image forming apparatus according to claim 1.

4. The torque reduction control described above is An operation to drive the image carrier at a slower speed than usual, The operation of supplying toner from the developer carrier to the image carrier, The operation of increasing the toner concentration in the developer carrier, The operation of lowering the voltage applied to the developer carrier, The operation of lowering the surface potential of the image carrier, An operation to change the output of the transfer means that contacts the image carrier, The operation of changing the position of the transfer means, An operation to reduce the contact force of the cleaning member that contacts the image carrier, including at least one of the following: The image forming apparatus according to claim 1.

5. The determination unit determines that the rotational torque is greater than the threshold if the rotational torque exceeds the threshold at least once, if the rotational torque exceeds the threshold for a predetermined number of times, or if the time integral value of the rotational torque that exceeds the threshold exceeds a predetermined value. The image forming apparatus according to claim 1.

6. The torque control unit executes the torque reduction control a number of times corresponding to the rotational torque detected by the detection unit. The image forming apparatus according to claim 1.

7. The system includes a notification unit that notifies the system if the determination unit determines that the rotational torque is greater than the threshold value. The image forming apparatus according to claim 1.

8. The notification unit includes at least one of a display unit capable of displaying information and a communication unit capable of communicating with an external device. The image forming apparatus according to claim 7.

9. A control method for an image forming apparatus comprising an image carrier and a drive unit capable of rotating the image carrier, The control unit, A detection step for detecting the rotational torque of the image carrier, A determination step of determining whether the rotational torque is greater than a threshold, If the determination step determines that the rotational torque is greater than the threshold, a torque control step is performed to execute torque reduction control to reduce the rotational torque. A control method for executing this.

10. A control program for an image forming apparatus comprising an image carrier and a drive unit capable of rotating the image carrier, Computers, A detection unit for detecting the rotational torque of the image carrier, A determination unit that determines whether the rotational torque is greater than a threshold, If the determination unit determines that the rotational torque is greater than the threshold, the torque control unit executes torque reduction control to reduce the rotational torque. A control program that makes it function as such.

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