JP2020118736A - Image forming device - Google Patents

Abstract

To provide an image forming device capable of detecting an error of maintaining a clutch of a toner supply drive unit in a connected state.SOLUTION: An image forming device 100 has a toner supply drive unit clutch 163 capable of transmitting a driving force of a development motor 111 of a development screw 409 provided to a developer 51 to a supply screw 405. The image forming device 100 is configured to determine an abnormality of the toner supply drive unit clutch 163 based on the state of the toner supply drive unit clutch 163 in a non-connected control and a detection result of a screw rotation sensor 431 by a housing door open/close sensor 435 when the development motor 111 is driven in a state where a housing door 401 is closed.SELECTED DRAWING: Figure 6

Description

The present invention relates to a determination process for determining an abnormality of a clutch that transmits a driving force from a drive source to a screw for supplying toner to a developing unit.

In the image forming apparatus, toner forms an electrostatic latent image on a photoconductor, and the electrostatic latent image formed on the photoconductor is developed using the toner. Such an image forming apparatus includes a developing device. In this image forming apparatus, the toner in the developing device is consumed by forming an image, and therefore, it is necessary to use a detachable container and supply the toner from the container to the developing device as appropriate. The image forming apparatus supplies the toner from the container to the developing device by rotating the supply screw.

Further, the image forming apparatus includes a developing screw for conveying and stirring the toner in the developing device, and a clutch for transmitting the driving force of the driving source to the developing screw. This image forming apparatus determines whether or not the developing screw is rotating based on the output value of the sensor that detects the toner in the developing device.

JP, 2018-194701, A

By the way, in order to reduce the number of drive sources, it is considered to provide a clutch between the replenishment screw and the drive source in order to transmit the driving force from the drive source to the replenishment screw that replenishes the developer to the developer. ..

However, if the clutch between the replenishment screw and the drive source fails, the toner may be excessively replenished to the developing device.

Then, the objective of this invention is detecting the abnormality of the clutch provided between the drive source and the supply screw.

In order to solve the above-mentioned problems, an image forming apparatus of the present invention is an image forming apparatus in which a container containing toner is removable, and the image forming apparatus described above is used for forming an electrostatic latent image on a photoconductor and the photoconductor. An exposing unit that exposes a photoconductor, a developing unit that develops the electrostatic latent image formed on the photoconductor using toner, and a developing unit that is provided in the developing unit and that stirs the toner of the developing unit. A developing screw that rotates, a drive source that rotates the developing screw, a mounting portion in which a container that stores the toner for replenishing the developing device is mounted, and the toner is supplied to the developing device by rotating. A replenishing screw for replenishment, an electromagnetic clutch controlled to a connected state for transmitting the driving force of the drive source to the replenishing screw, and an uncoupled state for not transmitting the driving force of the drive source to the replenishing screw, and the housing A door that is opened/closed for mounting a container, an opening/closing detection unit that detects the opening/closing of the door, a flag detection unit that detects a flag provided on the developing screw, and the electromagnetic clutch are controlled in a non-connected state. State, and control for determining the abnormality of the electromagnetic clutch based on the detection result obtained by the detection result of the flag detection means when the drive source is driven by the opening/closing detection means when the door is closed And means.

According to the present invention, the abnormality of the clutch provided between the drive source and the supply screw can be detected.

Schematic cross-sectional view of the image forming apparatus 100 Control block diagram of the image forming apparatus 100 Sectional drawing of principal parts of developing device 51 and replenishing mechanism Timing chart of toner supply control Flow chart of diagnostic process Flow chart of clutch state determination processing

FIG. 1 is a schematic sectional view of the image forming apparatus. The image forming apparatus 100 is a full color printer having a plurality of image forming units 1a, 1b, 1c and 1d. The image forming unit 1a forms a yellow toner image, the image forming unit 1b forms a magenta toner image, the image forming unit 1c forms a cyan toner image, and the image forming unit 1d forms a black toner image. To do. The intermediate transfer belt 3 functions as an intermediate transfer member to which the toner images formed by the image forming units 1a, 1b, 1c, and 1d are transferred.

The separation roller 8 sends the sheets P to the registration roller 9 while separating the sheets P one by one from the cassette 4. The registration roller 9 conveys the sheet P to the secondary transfer area Te to which the toner image on the intermediate transfer belt 3 is transferred.

The image forming units 1a, 1b, 1c, and 1d have substantially the same configuration except that the colors of toners used in the respective developing devices are different from yellow, magenta, cyan, and black. The image forming unit 1d will be described below, but the suffix of the reference numeral is omitted except when necessary.

The image forming unit 1 is a process cartridge including the photosensitive drum 10. The photosensitive drum 10 has a photosensitive layer (photosensitive member) formed on the outer peripheral surface of an aluminum cylinder, and is rotated by a drum motor 110 (FIG. 2). The charging roller 41 incorporated in the image forming unit 1 charges the surface of the photosensitive drum 10.

The exposure device 6 includes a light source, a polygon mirror, and an optical system. The exposure device 6 controls the light source based on the laser drive signal generated based on the image data, and controls the rotation of the polygon mirror. The laser light from the light source is changed by a polygon mirror or an optical system and scans the surface of the rotating photosensitive drum 10. As a result, an electrostatic latent image is formed on the photosensitive drum 10. The developing device 51 incorporated in the image forming unit 1 develops the electrostatic latent image on the photosensitive drum 10 with toner. As a result, the toner image is carried on the photosensitive drum 10.

The primary transfer roller 2 presses the intermediate transfer belt 3 to form a primary transfer area T (Ta, Tb, Tc, Td) between the photosensitive drum 10 and the intermediate transfer belt 3. By applying a voltage to the primary transfer roller 2, the toner image carried on the photosensitive drum 10 is transferred to the intermediate transfer belt 3 passing through the primary transfer area T.

The intermediate transfer unit 20 is a replacement unit that is disposed above the image forming unit 1 and that can be integrally attached to and detached from the image forming apparatus 100 without attachment/detachment related to rotational driving, and supports the intermediate transfer belt 3. Mechanism and drive mechanism.

The intermediate transfer belt 3 is wound around a secondary transfer inner roller 25, a belt driving roller 26, and tension rollers 27, 28 and 29. The intermediate transfer belt 3 is rotated in the arrow R2 direction by driving the belt driving roller 26. The intermediate transfer belt 3 is an endless belt member.

The intermediate transfer unit 20 also includes an optical sensor 80 that detects a toner image on the intermediate transfer belt 3.

Primary transfer rollers 2a, 2b, 2c and 2d are assembled in the intermediate transfer unit 20 so as to correspond to the image forming units 1a, 1b, 1c and 1d. The primary transfer rollers 2a, 2b, 2c, and 2d are spring-biased toward the photosensitive drums 10a, 10b, 10c, and 10d, respectively, so that the intermediate transfer belt 3 contacts the photosensitive drums 10a, 10b, 10c, and 10d. Then, the primary transfer area of the toner image is formed.

The secondary transfer area Te corresponds to the nip portion between the intermediate transfer belt 3 and the secondary transfer outer roller 22. The outer secondary transfer roller 22 presses the intermediate transfer belt 3 toward the inner secondary transfer roller 25. When a voltage is applied to the secondary transfer outer roller 22 from a power source (not shown), a transfer electric field is formed between the secondary transfer inner roller 25 and the secondary transfer inner roller 25.

The fixing device 5 forms a heating nip by pressing a pressure roller 5b against a fixing roller 5a provided with a heater. The sheet P is heated and pressed during the process of being nipped and conveyed by the heating nip to melt the toner image and fix the full-color image on the surface. The discharge roller 11 discharges the sheet P having the image fixed by the fixing device 5 to the tray 7 of the image forming apparatus 100.

Next, FIG. 2 shows a control block diagram of the image forming apparatus 100.

Each unit of the image forming apparatus 100 is centrally controlled by the control unit 200. The control unit 200 plays a role of driving each load of the image forming apparatus 100, information collection and analysis of sensors, image control, and data exchange with the operation unit 202, that is, a user interface.

The internal configuration of the control unit 200 is equipped with the CPU 201a to fulfill the above-mentioned role. The CPU 201a executes various sequences associated with a predetermined image forming sequence according to a program stored in the ROM 201b of the control unit 200. The control unit 200 also includes a RAM 201c that functions as a system work memory in order to store rewritable data that needs to be temporarily or permanently stored. The RAM 201c stores, for example, a high voltage set value for the high voltage control unit 205, various data described below, image formation command information from the operation unit 202, and the like.

The operation unit 202 has an operation panel capable of inputting information such as a copy magnification and a density setting value set by the user. The operation unit 202 transmits the state of the image forming apparatus 100, for example, information indicating the number of images formed and whether or not image formation is in progress, data for indicating to the user the occurrence of a jam and the location thereof, and the operation unit 202 has it. Display on the display. In addition, the operation unit 202 displays guidance for adjustments such as registration position adjustments and density adjustments and initialization operations to the serviceman as necessary, and accepts user operations.

The image forming apparatus 100 has DC loads such as a motor, a clutch, and a solenoid, and sensors such as a photo interrupter and a micro switch arranged at various locations inside the apparatus. Various sensors are used to convey a transfer material and drive each unit by appropriately driving a motor and each DC load, and various sensors monitor the operation.

The CPU 201a obtains a sensor signal by allowing the signal from the various sensors 214 to be detected by a sensor IF 209 including a pull-up/pull-down circuit (not shown) and a filter circuit (not shown). The sensors connected to the sensor IF 209 include a toner presence/absence detection sensor 641, which detects the presence/absence of toner in the hopper 423, a screw rotation detection sensor 431, and a storage door opening/closing sensor 435. The motor control unit 207 controls each motor 212 based on signals from various sensors 214.

The image forming apparatus 100 includes a drum motor 110 that rotates the photosensitive drum 10, a developing motor 111 that drives the developing device 51, and a toner bottle rotation that drives the toner in the toner bottle 402 (FIG. 3) to be discharged to the developing device 51. A motor 160 is provided. The toner bottle 402 (FIG. 3) is a storage container that can be attached to and detached from the image forming apparatus 100 and that stores replenishment toner.

The image forming apparatus 100 also includes a clutch/solenoid 213. The clutch/solenoid 213 includes, for example, a toner replenishment drive unit clutch 163 that transmits the drive of the developing motor 111 to the paddle 425 at an appropriate timing. The toner supply drive unit clutch 163 is an electromagnetic clutch. The DC load control unit 208 is a control circuit that controls the clutch/solenoid 213.

Further, the CPU 201a inputs a high-voltage control signal from the high-voltage controller 205 to the high-voltage unit 206, and the high-voltage unit 206 includes the charging roller 41, the developing sleeve 421 in the developing device 51, the primary transfer roller 2, and the secondary transfer inner roller 25. Appropriate high voltage is applied to.

The fixing roller 5a has a built-in heater for heating the roller. The CPU 201a controls the heat generation of the heater by the AC driver 210. Further, the fixing device 5 is provided with a thermistor 204 for measuring the temperature of the heater.

After the A/D 203 converts the resistance value change of the thermistor 204 according to the temperature change of the fixing roller 5a into a voltage value, the CPU 201a acquires it as a digital value. The CPU 201a controls the AC driver 210 described above based on the temperature data. The image controller 220 also processes image data input from the outside and sends the image data to the image forming unit 1.

FIG. 3 is a cross-sectional view of essential parts of the developing device 51 and a replenishing mechanism that replenishes the developing device 51 with toner.

In FIG. 3, the toner bottle 402 is stored in the cylindrical mounting portion 400. When the toner bottle 402 is replaced, the storage door 401 is opened, the toner bottle 402 is taken out, and a new toner bottle 402 is inserted into the mounting portion 400 and stored. The door 401 is closed and the toner bottle 402 is stored. In synchronization with this opening/closing, a microswitch type storage door opening/closing sensor 435 arranged inside the entrance of the storage door 401 responds. The CPU 201a detects opening/closing of the storage door 401 according to this state. The storage door opening/closing sensor 435 is a sensor for detecting the opening/closing of the storage door 401.

The toner replenishment control from the toner bottle 402 to the hopper 423 is executed with the storage door 401 closed.

When the toner bottle rotation motor 160 is driven, the toner bottle 402 rotates via the gears 410 and 411, the toner in the toner bottle 402 is conveyed toward the discharge port 404, and the toner is supplied from the discharge port 404 to the hopper 423. To do. When the toner presence/absence detection sensor 641 for detecting the presence/absence of toner in the hopper 423 detects the “toner-free state”, the motor control unit 207 drives the toner bottle rotation motor 160 to supply the toner to the hopper 423. When the toner presence/absence detection sensor 641 detects the “toner present state”, the toner bottle rotation motor 160 is stopped and the toner supply to the hopper 423 is stopped.

Further, when the developing motor 111 is driven and the toner replenishing drive unit clutch 163 is connected to replenish toner from the hopper 423 to the developing device 51, the paddle 425 rotates via the gears 419, 420 and 422. As a result, toner is supplied from the hopper 423 to the transport path 424. Here, the hopper 423 and the transport path 424 function as a buffer unit in which replenishment toner is once replenished. Further, the supply screw 405 in the transport path 424 rotates via the gears 422 and 413, and the toner in the transport path 424 is discharged to the developing device 51 from the discharge port 407. Further, the gear 413 is provided with a flag 430 that rotates in synchronization with the supply screw 405. Further, a screw rotation detection sensor 431 which is a photo interrupter for detecting this flag is provided. The screw rotation detection sensor 431 is used for flag detection.

When the drum motor 110 is driven, the photosensitive drum 10 rotates via the gears 416 and 415, and a toner image of each color is formed on the drum surface. The photosensitive drum 10 is installed so as to contact the developing sleeve 421. The developing sleeve 421 is a conductive roller, and toner is moved from the developing sleeve 421 to the photosensitive drum 10 by applying a high voltage to the roller shaft and charging the roller shaft.

By rotating the developing screw 409 installed in parallel with the developing sleeve 421, the toner in the developing device conveyed from the conveying path is stirred and conveyed, and the toner is conveyed to the developing sleeve 421.

The developing sleeve 421 and the developing screw 409 can be rotated by the developing motor 111 regardless of whether the toner supply driving unit clutch 163 is connected or released. The driving force of the developing motor 111 is transmitted to the developing screw 409 via the gears 419 and 414, and is transmitted to the developing sleeve 421 via the gears 417 and 418. By rotating the developing screw 409, the toner in the developing device 51 is agitated and conveyed along the circulation path.

It is determined that the toner supply from the hopper 423 to the developing device 51 needs to be supplied to the developing device 51 by calculating the amount of toner used during image formation in the CPU 201a based on the image data input from the outside. Sometimes done.

FIG. 4 is a timing chart of toner supply control for supplying toner from the hopper 423 included in the supply mechanism to the developing device 51.

When there is an image formation request, the CPU 201a starts rotating the developing motor 111 at time T1. Next, when it is determined that toner replenishment is necessary based on the image data, the toner replenishment drive unit clutch 163 is engaged at time T2. In this figure, it is assumed that there is a supply request for three rotations of the supply screw 405.

Ideally, the supply screw 405 starts rotating in synchronization with the connection of the toner supply drive unit clutch 163. However, in reality, the supply screw 405 starts to rotate from time T3 after time T2 due to the influence of the load state of the supply screw 405 and individual variations of the toner supply drive unit clutch 163. After that, the output of the screw rotation detection sensor 431 changes according to the rotation phase of the supply screw 405. The first falling edge at time T4, the second falling edge at time T5, and the third falling edge at time T6 are detected.

When detecting the third trailing edge, the CPU 201a issues an instruction to open the toner replenishment drive unit clutch 163 at time T7. Ideally, the replenishment screw 405 should stop in synchronization with the release instruction of the toner replenishment drive unit clutch 163. However, in reality, even when the rotation of the supply screw 405 is stopped, the stop timing changes due to the influence of the load state of the supply screw 405 and the individual difference of the toner supply drive unit clutch 163. The supply screw 405 of the present embodiment is delayed from time T7 and stops rotating at time T8.

Here, the toner replenishment drive unit clutch 163 will be described in detail. The toner replenishment drive unit clutch 163 has a rotating member connected to the drive source (developing motor 111), a rotated member connected to the load (paddle 425 and replenishment screw 405), and a winding. In the toner replenishment drive unit clutch 163, an electromagnetic force is generated by the current flowing through the winding, and the rotating member and the rotated member are attracted to each other. As a result, the toner replenishment drive unit clutch 163 can transmit the rotational drive force of the drive source to the load.

That is, in the connected state in which the rotating member and the rotated member are attracted to each other, the rotating torque of the developing motor 111 can be transmitted to the paddle 425 and the supply screw 405 in the transport path 424. On the other hand, in the non-connected state where the rotating member and the rotated member are not attracted, the rotation torque of the developing motor 111 is not transmitted to the paddle 425 and the supply screw 405. Therefore, the paddle 425 and the supply screw 405 cannot rotate.

When the toner replenishment drive unit clutch 163 is in the engaged state, the paddle 425 and the replenishment screw 405 in the conveyance path 424 rotate, and the toner in the hopper 423 is replenished to the developing device 51 via the conveyance path 424. However, if the toner replenishment drive unit clutch 163 unintentionally maintains the connected state during image formation, the paddle 425 and the replenishment screw 405 in the conveyance path 424 rotate, and the toner is replenished to the developing device 51. Will continue to be. As a result, the toner may be excessively replenished to the developing device 51. Further, if the toner is excessively replenished to the developing device 51, the toner overflows from the developing device 51 and the inside of the image forming apparatus 100 is evacuated. There is a risk of contamination.

Therefore, it is necessary to determine whether the toner replenishment drive unit clutch 163 is not in the connected state due to an abnormality (whether the toner is continuously replenished to the developing device 51).

In order to determine the above content, the reaction of the screw rotation detection sensor 431 is performed at the timing when the connection instruction (excitation instruction) is not issued to the toner replenishment drive unit clutch 163 (when the toner replenishment to the developing device 51 is unnecessary). Check if there is. If the trailing edge is counted up at the timing when the connection instruction (excitation instruction) is not issued to the toner replenishment drive unit clutch 163, it is determined that the toner replenishment drive unit clutch 163 is abnormal. However, it is difficult to make a judgment simply by the above method for the following reasons.

As described above, the replenishment screw 405 is stopped later than the release instruction due to the load state of the replenishment screw 405 and the paddle 425, the individual variation of the toner replenishment drive unit clutch 163, and the like.

In a normal replenishing operation, the hopper 423 and the conveyance path 424 are in a state of being filled with toner. Therefore, the replenishment screw 405 and the paddle 425 are loaded with a load larger than a predetermined value. As a result, the flag 430 stops at a position far from the flag reading range of the screw rotation detection sensor 431.

However, in order to reduce the downtime of the apparatus, in the image forming apparatus that can perform the image forming operation in the state where the toner in the toner bottle 402 is exhausted, the image forming operation can be performed during the bottle replacement. In such a device, when the toner bottle 402 is being replaced, the load in the hopper 423 is reduced due to the decrease in the amount of toner filled in the hopper 423, and the flag 430 stops near the flag reading range of the screw rotation detection sensor 431. There is a case.

In this case, since the load in the hopper 423 is light, the screw rotation detection sensor 431 may react in synchronization with even a minute vibration due to the image forming operation. In the first place, when the toner bottle 402 is attached to or detached from the mounting portion 400, the toner bottle 402 may come into contact with the inner wall of the mounting portion 400. The vibration generated thereby may be transmitted through the inner wall, and the output of the screw rotation detection sensor 431 may change.

In the following description, a diagnostic process for surely and promptly diagnosing that the toner supply drive unit clutch 163 has no abnormality will be described with reference to the flowchart of FIG. Note that, for example, when the main power supply of the image forming apparatus 100 is turned on, the CPU 201a reads the diagnostic processing program from the ROM 201b into the RAM 201c and executes the diagnostic processing program.

When the diagnosis process is started, the CPU 201a drives the drum motor 110 and the developing motor 111 (S400), and executes clutch state determination to determine the state of the toner replenishment drive unit clutch 163 (S401). If no error is determined in the clutch state determination in step S401 (N in S402), the CPU 201a waits for 10 msec (S403), and then determines whether or not a command requesting image formation is input (S404). ). If there is no image formation request in step S404, the CPU 201a stops driving the drum motor 110 and the developing motor 111 (S405), and ends the diagnosis process.

On the other hand, when the image forming request is input in step S404, the CPU 201 shifts the processing to step S401, and executes the clutch state determination again while executing the image forming operation. That is, the CPU 201a executes the clutch state determination in parallel with the image forming operation when the image forming request is input after the main power of the image forming apparatus 100 is turned on. As a result, downtime of the image forming apparatus 100 can be suppressed, and an abnormality in the toner replenishment drive unit clutch 163 can be promptly detected.

If an error is determined in the clutch state determination in step S401, the CPU 201a stops driving the drum motor 110 and the developing motor 111 (S406), and ends the diagnostic process. As a result, it is possible to prevent the toner from overflowing from the developing device 51 even when an abnormality occurs in the toner replenishment drive unit clutch 163. Even when a command requesting image formation is input, the CPU 201a prohibits the image forming operation and notifies that an abnormality has occurred on the display of the operation unit 202.

Next, details of the clutch state determination processing executed in step S401 of FIG. 5 will be described with reference to the flowchart of FIG.

When the clutch state determination is started, the CPU 201a determines whether or not the toner replenishment drive unit clutch 163 is controlled to be in the disengaged state (S500). In step S500, the CPU 201a determines whether the DC load control unit 208 is supplying current to the toner replenishment drive unit clutch 163.

When it is determined in step S500 that the current is not supplied to the toner replenishment drive unit clutch 163, the CPU 201a determines whether the detection signal of the storage door open/close sensor 435 has a value corresponding to the closed state (S501). ). If the detection signal of the storage door open/close sensor 435 indicates the closed state in step S501, the CPU 201a determines that the toner bottle 402 is not being replaced.

When the CPU 201a controls the toner replenishment drive unit clutch 163 to the non-engaged state and the detection signal of the storage door open/close sensor 435 indicates the closed state, does the screw rotation detection sensor 431 detect the falling edge? It is determined whether or not (S502). When the falling edge is detected as the detection result of the screw rotation detection sensor 431 in step S502, the CPU 201a increments the error edge count A by 1 (S503). Next, the CPU 201a determines whether the value of the error edge count A is 10 or more (S504). If the value of the error edge count A is 10 or more in step S504, the CPU 201a detects an error in the toner replenishment drive unit clutch 163 and ends the clutch state determination process.

On the other hand, if the value of the error edge count A is less than 10 in step S504, the CPU 201a ends the clutch state determination process without detecting an error. Note that the threshold value of the edge count A is set to a value that prevents toner from overflowing from the developing device 51 due to unintended replenishment.

When it is determined in step S500 that the current is being supplied to the toner replenishment drive unit clutch 163, the CPU 201a rewrites the value of the error edge count A to 0 (S506) and ends the clutch state determination. This is because the screw rotation detection sensor 431 detects the falling edge when the toner replenishment drive unit clutch 163 is in the engaged state.

Even when the detection signal of the storage door open/close sensor 435 indicates the open state in step S501, the CPU 201a rewrites the value of the error edge count A to 0 (S506) and ends the clutch state determination. This is because there is a high possibility that the toner bottle 402 is being replaced, and the screw rotation detection sensor 431 may detect the falling edge.

If the screw rotation detection sensor 431 does not detect the falling edge in step S502, or if the error edge count A is less than 10 in step S504, the clutch state determination is performed without performing any processing. To finish.

As described above, while the developing motor 111 is rotating, the toner replenishment drive unit clutch 163 is controlled to be in the non-connection state, and the storage door 401 is in the closed state, the CPU 201a causes the toner replenishment drive unit clutch 163 to operate. To determine the abnormality. As a result, it is possible to quickly detect an error in the toner replenishment drive unit clutch 163 and suppress erroneous detection. Then, although the replenishment to the developing device 51 is not necessary, the toner replenishment driving unit clutch 163 is maintained in the connected state, so that unintended toner replenishment to the developing device 51 can be suppressed. ..

402 toner bottle 10 photosensitive drum 6 exposure device 51 developing device 409 developing screw 111 developing motor 400 mounting portion 405 replenishing screw 163 toner replenishing drive unit clutch 401 storage door 435 storage door opening/closing sensor 431 screw rotation detection sensor 201a CPU

Claims (1)

An image forming apparatus in which a container containing toner is removable,
A photoconductor,
Exposure means for exposing the photoreceptor to form an electrostatic latent image on the photoreceptor;
Developing means for developing the electrostatic latent image formed on the photoreceptor with toner.
A developing screw which is provided in the developing means and rotates to agitate the toner of the developing means;
A drive source for rotating the developing screw,
A mounting portion to which a storage container storing the toner for replenishing the developing device is mounted,
A replenishing screw for replenishing the toner to the developing means by rotating,
An electromagnetic clutch controlled to a connected state in which the drive force of the drive source is transmitted to the supply screw and a non-connected state in which the drive force of the drive source is not transmitted to the supply screw,
A door that is opened and closed to mount the storage container,
An opening/closing detection means for detecting opening/closing of the door,
Flag detecting means for detecting a flag provided on the developing screw,
A state in which the electromagnetic clutch is controlled to be in a disengaged state, and a detection result of the flag detection unit when the drive source is driven by the opening/closing detection unit when the door is closed is acquired, and based on the detection result. And a control unit for determining abnormality of the electromagnetic clutch.

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