JP2017122772A - Image forming apparatus and method for controlling the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technology that can reduce a time required for determining abnormality that may occur in conveyance of toner in an image forming apparatus.SOLUTION: An image forming apparatus (MFP) detects a load applied to a conveyance path motor that conveys a toner discharged from a toner bottle to a developing unit and thereby monitoring the load (S102 to S104). The MFP determines whether the detected load varies in a variation pattern in a normal state where abnormality does not occur in conveyance of toner (S104), and when the load does not vary in the variation pattern in the normal state, executes a cancellation operation to cancel the abnormal state (S108).SELECTED DRAWING: Figure 6

Description

  The present invention relates to an electrophotographic image forming apparatus and a control method thereof.

  2. Description of the Related Art Conventionally, in an electrophotographic image forming apparatus such as a printer, a copying machine, or a facsimile machine, an electrostatic latent image formed on a photosensitive member is developed using a developer (toner) in a developing unit, thereby generating toner. Form an image. The toner image formed on the photosensitive member is transferred to a recording material such as a sheet, whereby a printed matter is generated. In such an image forming apparatus, the toner consumed in the developing device is supplied to the developing device from a toner bottle that can be replaced by the user.

  In the toner bottle or in the conveyance path from the toner bottle to the developing device, the fluidity of the toner may deteriorate due to solidification or fixation of the toner. In that case, the toner cannot be properly supplied from the toner bottle to the developing device, and the image forming quality may be deteriorated. For this reason, it is necessary to determine whether or not an abnormality has occurred in toner conveyance. If an abnormality has occurred, it is necessary to eliminate the abnormal state. In Patent Document 1, a load applied to a motor for driving a member for supplying toner from a toner bottle is detected, and when the number of times of detection of a load exceeding a specified value exceeds a predetermined number, the motor is fixed due to toner adhesion or the like. Describes an image forming apparatus that determines and reports that an abnormality has occurred. When the number of detections is less than the predetermined number, an abnormal state in the toner bottle is notified.

JP 2014-215601 A

  In the above-described prior art, when a load is applied to the motor, it is not immediately determined that an abnormality has occurred. The abnormal state of the motor or the abnormal state in the toner bottle is notified. In this case, a certain amount of time may be required until the load applied to the motor becomes a specified value or more. For this reason, it is desirable that an abnormality that may occur in the conveyance of toner from the toner bottle can be determined and resolved in a shorter time.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a technique capable of shortening the time required for determining an abnormality or the like that may occur in toner conveyance in an image forming apparatus. And

The present invention can be realized as an image forming apparatus, for example. An image forming apparatus according to an aspect of the present invention includes a conveying unit that conveys image forming toner, a motor that drives the conveying unit,
Detection means for detecting a load applied to the motor, and determination means for determining whether or not the state of conveyance by the conveyance means is a predetermined state based on a variation pattern of the load detected by the detection means; It is characterized by providing.

  According to the present invention, it is possible to further shorten the time required to determine an abnormality or the like that may occur in toner conveyance in the image forming apparatus.

FIG. 2 is a cross-sectional view illustrating a configuration of an MFP according to an embodiment. FIG. 3 is a schematic diagram illustrating a configuration of a toner supply unit according to an embodiment. FIG. 2 is a block diagram illustrating a configuration of a control system of the MFP according to an embodiment. FIG. 4 is a schematic diagram schematically illustrating an example of a toner conveyance state in a toner conveyance path according to an embodiment. The figure which shows the example of the time change of the load concerning the conveyance path motor which concerns on one Embodiment. 7 is a flowchart illustrating a procedure of a toner supply operation according to an embodiment.

  Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the drawings.

  The image forming apparatus according to the present embodiment is an apparatus that forms an image on a sheet by an electrophotographic method, such as a printing apparatus (printer), a copier, a multifunction peripheral (MFP), and a facsimile machine. Note that a multifunction peripheral is an apparatus having at least two or more functions among a plurality of types of functions including, for example, a print function, a scan function, a copy function, and a facsimile function. Here, a case where the image forming apparatus is an MFP having a printing function, a scanning function, and a copying function will be described.

<Image forming apparatus (MFP)>
FIG. 1 is a cross-sectional view illustrating a configuration of the MFP 100 according to the present embodiment. The MFP 100 may be an image forming apparatus that forms a multicolor image using a plurality of colors of toner (developer), but an image forming apparatus that forms a single color image using a single color toner will be described. The MFP 100 includes a printer unit 101 that forms an image on a sheet, a reader unit 102 that reads an image of a document, and an ADF unit 103 that transports a document to be read. The sheet may be referred to as recording paper, recording material, recording medium, paper, transfer material, transfer paper, or the like.

  In the printer unit 101, the recording paper P stored in the paper feed cassette 110 is fed to the transport path one by one by the pickup roller 111, the paper feed roller 112 and the retard roller 113. The recording paper P fed from the paper feed cassette 110 is transported along the transport path by the transport roller 114. When the recording paper P reaches the position of the registration roller pair 115, skew correction is performed by the stopped registration roller pair 115. Thereafter, when the registration roller pair 115 starts to rotate, the recording paper P is conveyed to the transfer nip portion between the photosensitive drum 131 and the transfer roller 133.

  In the printer unit 101, the laser scanner unit 120, the photosensitive drum (photosensitive member) 131, the charging roller 132, the transfer roller 133, and the developing device 140 constitute an image forming unit that forms an image on the recording paper P. In the image forming portion, the outer peripheral surface of the rotationally driven photosensitive drum 131 is uniformly charged to a predetermined polarity potential by the action of the charging roller 132. The laser scanner unit 120 exposes the charged photosensitive drum 131 with a light beam (laser light). Specifically, the laser scanner unit 120 outputs laser light L that is modulated according to image information (time-series digital pixel signals), and scans the charged photosensitive drum 131 with the laser light L, thereby performing photosensitivity. An electrostatic latent image is formed on the drum 131. The laser scanner unit 120 uses the laser beam L based on image data (image information) obtained by reading an image of a document by the reader unit 102 or image data received from an external device such as a PC via a network. Is output.

  The developing device 140 includes a developing roller 141 and develops the electrostatic latent image on the photosensitive drum 131 using toner supplied (supplied) from the toner replenishing unit 150 to form a toner image. The toner image formed on the photosensitive drum 131 moves to the transfer nip portion as the photosensitive drum 131 rotates. By applying a transfer bias having a polarity opposite to that of the photosensitive drum 131 to the transfer roller 133, the toner image on the photosensitive drum 131 is transferred to the surface of the recording paper P at the transfer nip portion.

  The recording paper P on which the toner image is transferred in the image forming unit is conveyed into the fixing device 160. The fixing device 160 fixes the toner image on the recording paper P to the recording paper P by applying heat and pressure to the recording paper P by a fixing heater and a pressure roller. The recording paper P on which an image has been formed in this manner is discharged (discharged) to the discharge tray 171 outside the apparatus by the discharge roller 170 after passing through the fixing device 160.

  When double-sided printing is performed on the recording paper P, the recording paper P on which image formation on the first surface has been completed is transported in the reverse direction by the paper discharge roller 170 after passing through the position of the reverse flapper 181 and reversed. It is guided to the reverse conveyance path 180 by the flapper 181. The recording paper P guided to the reverse conveyance path 180 is conveyed again to the position of the registration roller pair 115 by the conveyance rollers 182 and 183. At that time, the recording paper P is in a state in which the first surface and the second surface are reversed as compared with the image formation on the first surface. Thereafter, the recording paper P is discharged to the paper discharge tray 171 after the image formation on the second surface is performed in the same manner as the image formation on the first surface.

<Toner supply part>
FIG. 2 is a schematic diagram illustrating the configuration of the toner replenishing unit 150 in the MFP 100. A toner bottle (toner storage container) 200 pre-filled with toner is installed in the toner supply unit 150 by the user. The toner supply unit 150 includes a toner bottle 200, a bottle motor 201, a toner transport path 210, a screw 212 provided in the toner transport path 210, and a transport path motor 211. The toner conveyance path 210 is provided between the toner bottle 200 and the developing device 140 and corresponds to a toner hopper (storage unit) that stores toner discharged (supplied) from the toner bottle 200. The toner conveyance path 210 is used for conveying the toner discharged from the toner bottle 200 to the developing device 140.

  The rotation axis of the toner bottle 200 is connected to the bottle motor 201 via a drive gear train (not shown), and a rotational driving force can be applied from the bottle motor 201 via the drive gear train. When the bottle motor 201 is driven to rotate, the toner bottle 200 rotates in the direction indicated by the arrow A. As the toner bottle 200 is driven and rotated by the bottle motor 201, the toner is discharged from the inside of the toner bottle 200 and flows into the toner conveyance path 210.

  A screw 212 is provided in the toner conveyance path 210. The rotation shaft of the screw 212 is connected to the conveyance path motor 211 via a drive gear train (not shown), and a rotational driving force is applied from the conveyance path motor 211 via the drive gear train. As described above, a power transmission mechanism that transmits a driving force from the conveyance path motor 211 to the screw 212 is provided between the conveyance path motor 211 and the screw 212. The screw 212 is driven and rotated by the conveyance path motor 211 to convey the toner flowing from the toner bottle 200 into the toner conveyance path 210 in one direction (from left to right in FIG. 2). The toner conveyed through the toner conveyance path 210 is discharged to the developing device 140 at the end of the toner conveyance path 210. Note that a toner sensor 221 for detecting the presence or absence of toner in the developing device 140 is provided inside the developing device 140.

<MFP control system>
FIG. 3 is a block diagram showing the configuration of the control system of MFP 100 according to the present embodiment. FIG. 3 shows a configuration particularly related to the present embodiment, such as determination processing relating to replacement of the toner bottle 200 described later. The MFP 100 includes a CPU 400, a ROM 401, a RAM 402, and an EEPROM 403 as a control system.

  The ROM 401 stores a control program for controlling the entire MFP 100. The RAM 402 is a volatile storage device (memory) that is used as a work area of the CPU 400 and is used for temporarily storing various data such as image data. CPU 400 controls MFP 100 as a whole by reading a control program stored in ROM 401 into RAM 402 and executing it. The EEPROM 403 is a non-volatile storage device (memory) and is used to hold various data such as the remaining amount of toner in the toner bottle 200.

  The operation unit 410 includes a display unit (liquid crystal display or the like), receives a user operation, transmits operation information indicating the content of the user operation to the CPU 400, and operates an operation screen based on the screen information transmitted from the CPU 400. Is displayed on the display. The CPU 400 can notify the user of the occurrence of an error by displaying an error using the operation unit 410 when, for example, an abnormality occurs in the toner conveyance from the toner bottle 200 to the developing device 140. .

  The MFP 100 includes a motor drive circuit 411 that drives the bottle motor 201 by supplying a drive current to the bottle motor 201, and a motor drive circuit 412 that drives the transport path motor 211 by supplying a drive current to the transport path motor 211. Yes. The CPU 400 controls the operation of the toner replenishing unit 150 by performing drive control of the bottle motor 201 and the conveyance path motor 211 via the motor drive circuits 411 and 412, respectively. In this embodiment, as will be described later, the CPU 400 detects a load applied to the conveyance path motor 211, and an abnormality occurs in the toner conveyance by the screw 212 in the toner conveyance path 210 based on the detected fluctuation pattern of the load. It is determined whether or not. A load fluctuation pattern applied to the conveyance path motor 211 for comparison with the detected load fluctuation pattern is stored in the EEPROM 403. The CPU 400 detects the value of the drive current supplied from the motor drive circuit 412 to the transport path motor 211 as a load applied to the transport path motor 211. Note that the motor drive circuit 412 is provided with a resistor for current detection, and the CPU 400 can detect the value of the drive current by the resistor.

  A signal output from the toner sensor 221 of the developing device 140 is input to the CPU 400. The CPU 400 controls the supply (replenishment) of toner from the toner replenishing unit 150 to the developing device 140 based on the signal output from the toner sensor 221. When the CPU 400 detects that there is no toner in the developing device 140 based on the output signal from the toner sensor 221, the toner replenishing operation (supplying) for replenishing (supplying) toner from the toner bottle 200 to the developing device 140. Operation). Specifically, the CPU 400 replenishes toner from the toner bottle 200 to the toner conveyance path 210 by driving the bottle motor 201 to rotate the toner bottle 200. Further, the CPU 400 drives the conveyance path motor 211 to rotate the screw 212 to convey the toner in the toner conveyance path 210 and replenish the toner from the toner conveyance path 210 to the developing device 140.

<Decision processing based on load fluctuation pattern>
In the present embodiment, the CPU 400 detects a load applied to the conveyance path motor 211 and determines whether or not an abnormality has occurred in toner conveyance by the screw 212 in the toner conveyance path 210 based on the detected fluctuation pattern of the load. To do. In the following, first, a variation pattern of a load applied to the conveyance path motor 211 will be described with reference to FIGS. 4 and 5. FIG. 4 is a schematic diagram schematically illustrating an example of a toner conveyance state in the toner conveyance path 210. FIG. 4 shows a change in toner conveyance state from the start of toner discharge from the toner bottle 200 at time T1 to time T8. Times T1 to T8 in FIG. 4 correspond to times T1 to T8 shown in FIG. The times T1 to T8 correspond to the timing at which the CPU 400 detects the value of the drive current supplied from the motor drive circuit 412 to the conveyance path motor 211, that is, the CPU 400 monitors the value of the drive current at a predetermined time interval. (Monitoring). As described above, the toner discharged from the toner bottle 200 is supplied into the toner conveyance path 210 through the opening provided at one end of the toner conveyance path 210, and the opening provided at the other end of the toner conveyance path 210. And is discharged into the developing device 140.

  In the present embodiment, the CPU 400 repeats the discharge of toner from the toner bottle 200 to the toner transfer path 210 and the stop of the discharge of the toner at a fixed period while rotating the transfer path motor 211 at a fixed rotation speed. 4 and 5, the CPU 400 discharges the toner from the toner bottle 200 from time T1 to T4, and temporarily stops discharging the toner from the toner bottle 200 from time T5 to T7. Thereafter, the CPU 400 resumes the discharge of the toner from the toner bottle 200 at time T8. In this way, the CPU 400 periodically controls the discharge of toner from the toner bottle 200 to the toner conveyance path 210.

  Here, FIG. 5A shows a change over time of the load applied to the conveyance path motor 211 when a normal state in which no abnormality occurs in toner conveyance in the toner conveyance path 210 continues. In FIG. 5A, when the drive of the conveyance path motor 211 is started and the screw 212 starts to rotate, the load applied to the conveyance path motor 211 starts to increase. At time T1 to T4, as shown in FIG. 4, the load applied to the transport path motor 211 as the amount of toner discharged from the toner bottle 200 to the toner transport path 210 and transported on the toner transport path 210 by the screw 212 increases. Has increased.

  After the time T4, at time T5 to T8, toner discharge from the toner bottle 200 to the toner transport path 210 is stopped, and toner is discharged from the toner transport path 210 to the developing device 140, so that toner transport is performed. The amount of toner conveyed in the path 210 is reduced. For this reason, in FIG. 5A, the load applied to the conveyance path motor 211 decreases from time T4 to T8. Thereafter, when the discharge of the toner from the toner bottle 200 is resumed at time T8, the load applied to the transport path motor 211 starts to increase again. As described above, when the normal state in which no abnormality occurs in the toner conveyance in the toner conveyance path 210 continues, the load applied to the conveyance path motor 211 increases periodically according to the discharge pattern of the toner from the toner bottle 200. It fluctuates in a pattern of repeating and decreasing.

  Next, FIG. 5B and FIG. 5C show a change with time in the load applied to the conveyance path motor 211 when abnormality occurs in the toner conveyance in the toner conveyance path 210. FIG. 5B shows a case where toner clogging occurs due to toner solidification or the like in the toner conveyance path 210 at time Tx. In this case, after time Tx, the load applied to the transport path motor 211 continues to increase due to the toner that is discharged from the toner bottle 200 and continues to accumulate in the toner transport path 210. Finally, at time Ty, the operation of the conveyance path motor 211 is stopped (motor lock is generated).

  FIG. 5C shows a case where the rotating shaft of the screw 212 is broken at time Tz (when an abnormality occurs in the driving force transmission mechanism). In this case, the driving force is not transmitted from the conveyance path motor 211 to the screw 212, so that toner cannot be conveyed, and no load is applied to the conveyance path motor 211 from the screw 212. For this reason, after time Tz, the load applied to the conveyance path motor 211 is substantially zero.

  As can be seen from FIGS. 5B and 5C, when an abnormality occurs in toner conveyance in the toner conveyance path 210, the load applied to the conveyance path motor 211 is a pattern in the normal state shown in FIG. 5A. It starts to fluctuate in a different pattern. In the present embodiment, the CPU 400 detects a load applied to the conveyance path motor 211, and the detected load varies in a predetermined pattern corresponding to a variation pattern in a normal state as illustrated in FIG. Is determined that there is no abnormality in toner conveyance. On the other hand, when the load applied to the conveyance path motor 211 does not vary in a predetermined pattern, it is determined that an abnormality has occurred in toner conveyance.

  In the determination process described above, if a load fluctuation pattern begins to deviate from a predetermined pattern due to an abnormality in toner conveyance in the toner conveyance path 210, the load may be even before the load deviates from the normal range. Thus, it can be determined that an abnormality has occurred in toner conveyance. Therefore, it is possible to determine in a relatively short time that an abnormality has occurred in toner conveyance in the toner conveyance path 210.

<Example of toner supply operation>
FIG. 6 is a flowchart illustrating a procedure of a toner supply operation executed in the MFP 100 according to the present embodiment. 6 is implemented in MFP 100 under the control of CPU 400 by CPU 400 reading out and executing a control program from ROM 401.

  When the image forming operation is started in the MFP 100, the CPU 400 starts driving the bottle motor 201 and the conveyance path motor 211 in S101 to start supplying toner from the toner bottle 200 to the developing device 140. During the execution of the image forming operation, the bottle motor 201 is repeatedly driven and stopped at a constant cycle. The CPU 400 drives the bottle motor 201 to replenish toner from the toner bottle 200 to the toner conveyance path 210 every time it detects that the toner in the developing device 140 is absent or insufficient using the toner sensor 221.

In step S <b> 102, the CPU 400 starts monitoring a load applied to the conveyance path motor 211. Note that the CPU 400 detects the value of the current flowing through the current detection resistor provided in the motor drive circuit 412 as a load applied to the conveyance path motor 211 as described above. Thereafter, in S103, the CPU 400 determines whether or not the detected load is below a threshold value I _min corresponding to the minimum value of the load when there is no abnormality in toner conveyance in the toner conveyance path 210. When the detected load is lower than the threshold value I _min as in the state after time Tx in FIG. 5C, the CPU 400 advances the process to S107. In S107, the CPU 400 determines that an abnormality has occurred in the power transmission mechanism for the conveyance path motor 211 (for example, the rotation shaft of the screw 212 is broken). Further, after notifying the user of the occurrence of an error using the operation unit 410, the CPU 400 stops driving the bottle motor 201 and the conveyance path motor 211 and ends the process.

On the other hand, if the detected load is not less than the threshold value I _min , the CPU 400 advances the process from S103 to S104. In S <b> 104, the CPU 400 compares the detected load with the fluctuation pattern (normal pattern) in the normal state stored in the EEPROM 403 to determine whether or not the load fluctuates in the normal pattern. If the CPU 400 determines that the load is fluctuating in a normal pattern, the process proceeds to S105, and if it is determined that the load is not fluctuating in a normal pattern, the process proceeds to S108.

  In the determination process in S104, for example, the load being detected is between a maximum value and a minimum value of the load in a normal state (that is, within a normal range) in a predetermined time (time from T1 to T8 in FIG. 5). You may implement | achieve by determining whether it is changing. In that case, when the load being detected transitions between the maximum value and the minimum value, the CPU 400 determines that there is no abnormality in toner conveyance, and between the maximum value and the minimum value. If there is no transition, it may be determined that an abnormality has occurred in toner conveyance. Further, each of the maximum value and the minimum value may be determined as an average value obtained by measurement performed under a condition in which no abnormality occurs in toner conveyance. Thereby, the error which arises in the result of the above-mentioned judgment processing by the variation of the load for every apparatus can be reduced.

  In S105, the CPU 400 determines whether or not to end the toner supply operation. If not, the process returns to S103, and if it ends, the process proceeds to S106. The CPU 400 continues the processing from S103 to S105 at a predetermined time interval until the toner supply operation is finished (in the example of FIG. 5, it is performed eight times per cycle). Note that the CPU 400 ends the toner supply operation when the image forming operation ends. In S <b> 106, the CPU 400 ends the process by terminating the driving of the bottle motor 201 and the conveyance path motor 211.

  On the other hand, in S <b> 108, the CPU 400 executes a canceling operation for canceling the abnormal toner transport state in the toner transport path 210. The canceling operation is, for example, an operation of alternately switching the rotation of the conveyance path motor 211 between a normal rotation and a reverse rotation, an operation of changing the rotation speed of the conveyance path motor 211, or an electric power for driving the conveyance path motor 211 It is an operation to change the value. The CPU 400 counts the number of times that the cancellation operation has been executed continuously (the number of continuous executions) each time the cancellation operation is executed in S108. After that, in S109, the CPU 400 determines whether or not the number of continuous executions of the abnormal state elimination operation has reached a specified number. If the number of consecutive executions of the canceling operation has not reached the specified number, the CPU 400 advances the process to S105, and if it has reached the specified number, advances the process to S110.

  As described above, when the toner conveyance abnormal state cannot be resolved even if the elimination operation is continuously repeated a predetermined number of times, the conveyance path motor 211 finally reaches the motor lock state, so that the operation of the conveyance path motor 211 is performed. Stop. In this case, in S110, the CPU 400 determines that toner clogging that cannot be eliminated by the elimination operation has occurred in the toner conveyance path 210 and that the conveyance path motor 211 has been locked. Furthermore, after notifying the user of the occurrence of an error using the operation unit 410, the CPU 400 stops driving the bottle motor 201 and ends the process.

  As described above, according to the present embodiment, it can be determined in a relatively short time that an abnormality has occurred in toner conveyance in the toner conveyance path 210. Therefore, it is possible to shorten the time required for determining an abnormality that may occur in the conveyance of toner from the toner bottle 200 to the developing device 140 in the MFP 100.

100: MFP (image forming apparatus), 131: photosensitive drum, 140: developing device, 150: toner replenishing unit, 200: toner bottle, 201: bottle motor, 210: toner transport path (toner hopper), 211: transport path motor 212: Screw, 213, 221: Toner sensor, 400: CPU, 403: EEPROM

Claims (14)

A conveying means for conveying image forming toner;
A motor for driving the conveying means;
Detecting means for detecting a load applied to the motor;
A determination unit that determines whether or not a state of conveyance by the conveyance unit is a predetermined state based on a variation pattern of a load detected by the detection unit;
An image forming apparatus comprising: A storage means for storing a variation pattern when the state of the transport by the transport means is the predetermined state;
The determination unit determines that no abnormality has occurred in the state of conveyance when the load detected by the detection unit varies in a variation pattern stored in the storage unit, and the load 2. The image forming apparatus according to claim 1, wherein when there is no change in the change pattern stored in the storage unit, it is determined that an abnormality has occurred in the conveyance state. In the case where the load detected by the detection unit has transitioned between a maximum value and a minimum value of the load when no abnormality has occurred in the conveyance state in a predetermined time. If it is determined that no abnormality has occurred in the conveyance state and the load has not changed between the maximum value and the minimum value in a predetermined time, an abnormality has occurred in the conveyance state. The image forming apparatus according to claim 1, wherein the image forming apparatus determines whether the image is present. The image forming apparatus according to claim 3, wherein each of the maximum value and the minimum value is an average value obtained by measurement performed under a condition in which no abnormality occurs in the conveyance state. 5. The apparatus according to claim 1, further comprising a control unit that executes a canceling operation for eliminating the abnormal state of the conveyance when the determination unit determines that an abnormality has occurred in the conveyance state. The image forming apparatus according to any one of the above. The canceling operation is an operation of alternately switching the rotation of the motor between a normal rotation and a reverse rotation, an operation of changing the rotation speed of the motor, or an operation of changing a power value for driving the motor. The image forming apparatus according to claim 5. The control means executes the elimination operation every time it is judged by the judgment means that an abnormality has occurred in the conveyance state, and when the number of consecutive executions of the elimination operation reaches a predetermined number of times, the motor The image forming apparatus according to claim 5, wherein the operation is stopped. The image forming apparatus according to claim 7, further comprising notification means for notifying a user of the occurrence of an error when the operation of the motor is stopped because the number of executions of the elimination operation reaches the predetermined number of times. apparatus. The determination means further, when the load detected by the detection means falls below a threshold value corresponding to the minimum value of the load when there is no abnormality in the conveyance state, from the motor to the conveyance means. The image forming apparatus according to claim 1, wherein it is determined that an abnormality has occurred in the transmission mechanism that transmits the driving force. The image forming apparatus according to claim 9, further comprising a notification unit that notifies the user of the occurrence of an error when the determination unit determines that an abnormality has occurred in the transmission mechanism. A drive circuit for supplying a drive current to the motor to drive the motor;
The image forming apparatus according to claim 1, wherein the detection unit detects the value of the drive current supplied from the drive circuit to the motor as the load. The image forming apparatus according to claim 11, wherein the detection unit detects the drive current by a current detection resistor provided in the drive circuit. 13. The screw according to claim 1, wherein the transport unit is a screw provided in a toner transport path between the toner storage container and the developing device and driven to rotate by the motor. Image forming apparatus. A control method for an image forming apparatus, comprising: a transport unit that transports toner for image formation; and a motor that drives the transport unit,
A detection step of detecting a load applied to the motor;
A determination step of determining whether or not the state of conveyance by the conveyance means is a predetermined state based on the load variation pattern detected in the detection step;
A control method for an image forming apparatus.

Images