JP2020095153A - Image forming device - Google Patents

Abstract

To provide an image forming device capable of properly setting a reference value of an inductance detection sensor even if an installer has erroneously installed a toner container before an initial operation.SOLUTION: In initial operation, it is determined whether toner is supplied from the toner container T to the developing device 4a before the sensor adjustment for setting the reference value of the inductance detection sensor 32 is performed. When the toner is supplied from the toner container T to the developing device 4a before the sensor adjustment is performed, a series of toner ejection processing for ejecting toner from the developing device 4a is performed by forming a pattern image, and the sensor adjustment is performed after the toner ejection processing is performed.SELECTED DRAWING: Figure 7

Description

The present invention relates to a bufferless electrophotographic image forming apparatus in which a toner outlet of a toner container is arranged so as to communicate with a toner inlet of a developing device.

Conventionally, the image forming apparatus needs to replenish the toner as the toner is consumed. Therefore, the image forming apparatus is provided with a detachable toner container.

On the other hand, in a bufferless configuration in which the toner outlet of the toner container is connected to the toner inlet of the developing device, when the toner container is attached to the main body of the device, the toner inlet of the developing device is connected to the toner outlet. Toner leaks into the developing device. Therefore, a shutter that can be opened and closed is provided at the discharge port so that the toner does not leak from the toner discharge port. The opening and closing of the shutter is interlocked with the attachment/detachment operation, and it is conceivable that the shutter opens when the toner container is attached to the apparatus main body.

Further, for the purpose of reducing the packing size of the main body and reducing the packing material of the toner containing container, it is conceivable to pack and ship the toner containing container attached to the main body. Hereinafter, packing with the toner storage container mounted in the main body is defined as mounting bundle.

In the image forming apparatus of Patent Document 1, when the toner storage container is set in the image forming apparatus, the opening of the toner storage container is located right above the opening of the developing device. Then, in the image forming apparatus of Patent Document 1, the toner container is brought into a contact state in which the developing container is in close contact with the developing device (a state in which both openings are in communication) by moving the entire developing device upward. As a result, the toner is appropriately replenished from the toner container to the developing device, and the toner leakage during that time can be suppressed.

JP, 08-110692, A

In Patent Document 1, the structure of the movable shutter opening/closing locking member leads to an increase in cost.

However, if the structure of the movable locking member is not adopted for the purpose of cost reduction, the toner leaks from the toner discharge port to the developing device during shipping when the toner container is attached and packed in the main body. This causes fluctuations in image density.

Therefore, it is possible to consider a configuration in which the toner discharge port and the developing device are included in a detached state and shipped in a half-attached state. In this case, it is important to properly mount the toner storage container after the initial operation is performed. This initial operation includes sensor adjustment for setting the reference value of the inductance detection sensor.

However, if the installer mistakenly mounts the toner storage container before the sensor adjustment, toner is supplied from the toner storage container to the developing device, and the reference value of the inductance detection sensor cannot be set correctly.

Therefore, an object of the present invention is to properly set the reference value of the inductance detection sensor even when the installer mistakenly mounts the toner storage container before the sensor adjustment.

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 in which toner is contained is detachable, and which has a developing device for accumulating a developer containing the toner. Forming means for forming an image using the toner of the container, a mounting portion to which the storage container is mounted, a replenishing means for supplying the toner from the storage container mounted to the mounting portion to the developing device, An inductance detection sensor which is provided in the developing device, detects the magnetic permeability of the developer in the developing device, and outputs an output value based on the detection result, and the output value and the reference value of the inductance detection sensor. Replenishment control means for controlling the replenishment means on the basis of the replenishment means, and control means for performing an initial operation including sensor adjustment for setting the reference value based on the output value of the inductance detection sensor. Determines whether the toner is supplied from the storage container to the developing device before the sensor adjustment is performed, and the toner is transferred from the storage container to the developing device before the sensor adjustment is performed. Is supplied, a toner discharge process for discharging the toner in the developing device is performed by forming a pattern image by the image forming unit, and the sensor adjustment is performed after the toner discharge process is performed. It is characterized by

According to the present invention, the reference value of the inductance detection sensor can be appropriately set even if the installer mistakenly mounts the toner storage container before the sensor adjustment.

Sectional view of essential parts of image forming apparatus Schematic sectional view of the developing device Schematic diagram of the main part of the toner container Diagram showing the relationship between the toner concentration and the output value of the inductance detection sensor Control block diagram of image forming apparatus Flowchart diagram showing toner supply control Flow chart showing the initial operation The figure showing the relationship between the initial reference signal Vref and the control voltage Vout. Transition diagram of detection output of inductance detection sensor

(Image forming device)
FIG. 1 is a schematic configuration diagram of an image forming apparatus according to an embodiment of the present invention. The image forming apparatus is an electrophotographic full-color printer having four image forming units. In this image forming apparatus, each image forming section is provided corresponding to each of four colors of magenta, cyan, yellow and black. The toner image on the photosensitive drum formed by each image forming unit is primarily transferred onto an intermediate transfer belt that moves in opposition to the photosensitive drum, and then secondarily transferred onto a transfer medium.

That is, as shown in FIG. 1, the photosensitive drums 2a, 2b, 2c, and 2d as image bearing members are provided in the magenta, cyan, yellow, and black image forming portions 1M, 1C, 1Y, and 1K, respectively. It is rotated in the direction of the arrow.

Around the photosensitive drums 2a, 2b, 2c, 2d, charging devices 3a, 3b, 3c, 3d, developing devices 4a, 4b, 4c, 4d, primary transfer charging devices 5a, 5b, 5c, 5d, and Drum cleaning devices 6a, 6b, 6c and 6d are arranged respectively. Further, laser scanners 7a, 7b, 7c and 7d, which are exposure devices, are arranged above the photosensitive drums.

Next, an image forming operation by the above image forming apparatus will be described.

When the image forming operation is started, first, the photosensitive drums 2a, 2b, 2c and 2d are uniformly charged by the chargers 3a, 3b, 3c and 3d. Next, an electrostatic latent image is formed by exposure with laser light corresponding to the image signals emitted from the laser scanners 7a, 7b, 7c, 7d. The electrostatic latent image is visualized by the toner accumulated in the developing devices 4a, 4b, 4c, 4d to become a visible image. In this embodiment, a reversal development method is used in which the toner is attached to the bright portion potential exposed by the laser light.

The toner images of the respective colors are sequentially superposed on the intermediate transfer body 8 by the primary transfer chargers 5a, 5b, 5c and 5d, and are conveyed to the secondary transfer section. A transfer medium such as paper stored in a paper feed cassette is fed at the timing when the toner image is conveyed to the secondary transfer unit, and the four color toner images are transferred onto the transfer medium by the secondary transfer rollers 10 and 15. Will be transferred at once.

Further, the transfer medium is separated from the intermediate transfer body 8, conveyed to the fixing device 13, and heated and pressed by the fixing device to obtain a full-color image. Further, the toner remaining on the photosensitive drums 2a, 2b, 2c, 2d without being completely transferred at the primary transfer portion is collected by the photosensitive drum cleaning devices 6a, 6b, 6c, 6d. Further, the toner remaining on the intermediate transfer body 8 without being completely transferred at the secondary transfer portion is collected by the cleaning device 8a, whereby a series of operations is completed.

(Control unit)
FIG. 5 is a block diagram of control according to the present invention. The control unit 100 is a control circuit that controls each unit of the image forming apparatus in FIG. The control unit 100 has a CPU 107, a ROM 106, and a RAM 105. In the CPU 107, a ROM 106 in which a control program is written and a RAM 105 functioning as a system work memory are connected by an address bus and a data bus. The inductance detection sensor 32 is provided in the developing devices 4a, 4b, 4c, and 4d (FIG. 2), and the toner concentration of the developer in the developing devices 4a, 4b, 4c, and 4d (FIG. 2) Output the output value according to the detection result of magnetic susceptibility. The inductance detection sensor 32 is provided for each of the developing devices 4a, 4b, 4c, 4d (FIG. 2). However, in order to simplify the description, one inductance detection sensor 32 is used in the present description.

The control unit 100 can communicate with the memory tag 101 provided in the developing devices 4a, 4b, 4c, 4d (FIG. 2). The memory tag 101 stores the initial reference signal Vref of the inductance detection sensor 32 (FIG. 2) in advance. The memory tag 101 is also provided for each of the developing devices 4a, 4b, 4c, 4d (FIG. 2). However, in order to simplify the description, one memory tag 101 is used in the description in this specification.

The display unit 102 is an operation panel that includes a liquid crystal display and a numeric keypad. For example, when the value of the detection output of the inductance detection sensor 32 is abnormal, a screen for notifying an error of the image forming apparatus is displayed on the liquid crystal display of the display unit 102. The developing drive motor 103 is a drive source for rotating the stirring screws 28 and 29 (FIG. 2) provided in the developing device 4 (4a, 4b, 4c, 4d).

The toner storage container detection sensor 221 is an optical sensor that detects the protrusion 222a of the toner storage container T. When the toner storage container T is mounted on the mounting portion, the protrusion 222a of the toner storage container T is detected by the toner storage container detection sensor 221. The CPU 107 determines whether or not the toner storage container T is mounted on the mounting portion based on the detection signal of the toner storage container detection sensor 221.

(Developer)
Next, the developing devices 4a, 4b, 4c and 4d will be described with reference to FIGS. 2(a) and 2(b). Since the plurality of developing devices 4a, 4b, 4c, and 4d have the same configuration, only the magenta developing device 4a will be described here.

The developing device used in this embodiment uses a two-component developing method. As shown in FIGS. 2A and 2B, the inside of the developing container 20 of the developing device 4a is divided by the partition wall 24. It is partitioned by the first chamber 25 and the second chamber 26. Each of the first chamber 25 and the second chamber 26 has an opening formed at each end, which communicates with the other. The developer container 20 contains a two-component developer t in which carrier particles, which are magnetic materials, and toner particles, which are non-magnetic materials, are mixed. Toner replenishing means is arranged above the second chamber 26, and toner is replenished into the second chamber 26 from the toner inlet 33. An inductance detection sensor 32 for detecting the toner concentration of the two-component developer is installed in the second chamber 26. The toner is replenished from the toner introduction port 33 into the second chamber 26 by the toner replenishing means according to the detection output of the inductance detecting sensor. A specific toner replenishment control method using the inductance detection sensor will be described later in detail.

A rotatable developing sleeve 21 including a fixed magnet 22 is arranged in an opening formed in a portion of the developing container facing the photosensitive drum 2a. A regulating blade 23 for regulating the developer t to a predetermined layer thickness is arranged near the developing sleeve 21.

A first stirring screw 27 as a transport member is installed in the first chamber 25, and a second stirring screw 28 as a transport member is installed in the second chamber 26. The first stirring screw 27 and the second stirring screw 28 are both rotationally driven to convey the developer while stirring them in the opposite directions of the longitudinal direction. As a result, the developer t circulates in the developing container 20. This cycle period is about 30 seconds. The toner replenished into the stirring chamber 26 from the toner inlet 33 is stirred by the rotating operation of the stirring screw 28 and frictionally charged with the carrier particles in the stirring chamber 26 to give a predetermined charge amount. The toner to which the charge amount is applied is transferred to the stirring screw 27 together with the carrier particles, and further transferred to the developing sleeve 21.

Due to the rotation operation of the developing sleeve 21, the toner conveyed to the portion (developing nip) facing the photosensitive drum 2a flies onto the photosensitive drum 2a by the developing bias applied to the developing sleeve 21. In this embodiment, a developing bias in which an AC component is superimposed on a DC component is used.

(Toner container)
FIG. 3 is a schematic view of a main part of the toner container T. FIG. 3A is an enlarged view of a main part of the toner container T that is attachable to and detachable from the mounting portion of the image forming apparatus. 3B and 3C are cross-sectional views of a main part showing a structure inside the cap portion 222 of the toner container T attached to the attachment portion.

The toner storage container T includes a storage portion 207 for storing toner, a drive transmission portion 206 to which a rotational driving force is transmitted from the toner storage container drive motor 604, and a discharge portion 212 having a discharge port 211 for discharging toner. Further, the toner container T includes a pump unit 210 for discharging the toner in the discharge unit 212 from the discharge port 211, and a reciprocating member 213 for expanding and contracting the pump unit 210. The drive transmission portion 206 has a convex portion 220 (predetermined portion) and a cam groove 214. The cam groove 214 is formed over the entire circumference of the drive transmission portion 206 in the rotation direction in which the drive transmission portion 206 of the toner container T rotates.

The cam groove 214 and the convex portion 220 formed on the drive transmission unit 206 rotate together with the drive transmission unit 206. The toner storage container drive motor 604 transmits the rotational driving force to the drive transmission unit 206 of the toner storage container T via the drive gear, so that the drive transmission unit 206 of the toner storage container T and the storage unit connected to the drive transmission unit 206. The part 207 rotates. The convex portion 205 is formed in a spiral shape inside the containing portion 207, and the toner in the containing portion 207 is conveyed toward the discharge port 211 as the containing portion 207 rotates.

Since the rotation of the cap portion 222 is restricted by the mounting portion, it does not rotate even if the drive transmission portion 206 rotates. The discharge port 211, the pump unit 210, and the reciprocating member 213 are also regulated so as not to rotate together with the cap unit 222. The discharge port 211, the pump unit 210, and the reciprocating member 213 do not rotate even if the drive transmission unit 206 rotates.

A rotation restricting groove that restricts rotation of the reciprocating member 213 due to rotation of the drive transmission unit 206 is formed inside the cap 222. The reciprocating member 213 is engaged with the rotation restricting groove. Further, the reciprocating member 213 is connected to the pump portion 210, and a not-shown claw portion engages with the cam groove 214 of the drive transmission portion 206. As a result, the reciprocating member 213 moves along the cam groove 214 in a state in which the reciprocating member 213 is restricted from rotating in response to the rotation of the drive transmission unit 206. Therefore, the reciprocating member 213 reciprocates in the arrow X direction (longitudinal direction of the toner container T).

The reciprocating member 213 is connected to the pump unit 210. When the reciprocating member 213 reciprocates, the pump portion 210 alternately repeats expansion and compression. The pump portion 210 extends as the reciprocating member 213 moves in the arrow X direction. Then, as the pump portion 210 expands, the internal pressure of the toner container T decreases, and air is sucked from the discharge port 211, so that the toner in the discharge portion 212 is released. Next, the reciprocating member 213 moves in the direction opposite to the arrow X direction, so that the pump portion 210 is compressed. Then, the internal pressure of the toner container T rises due to the compression of the pump portion 210, and the toner accumulated in the discharge port 211 is supplied from the discharge port 211 to the developing device 4 through the toner transport path.

The cap portion 222 has a protrusion 222a on the inner side in the mounting direction of the toner container T (direction of arrow M). The toner storage container detection sensor 221 provided in the image forming apparatus detects that the toner storage container T is mounted in the mounting portion.

Further, the following method may be used as the detecting means for detecting that the toner container T has been attached. The toner container T is provided with a memory tag, and the individual information of the toner container T is recorded in advance in the memory tag. When the toner container T is attached, the control unit 100 communicates with the memory tag to acquire this individual information. If the control unit 100 can communicate with the memory tag, the control unit 100 detects that the toner container T is attached to the attachment unit (the communication method is not shown).

When the toner storage container T is mounted on the mounting portion of the image forming apparatus, about 2.0 g of toner accumulated in the discharge port 211 flows into the developing device 4 from the discharge port 211 through the toner transport path.

(Toner supply control)
Next, the toner replenishment control method by the inductance detection sensor used in this embodiment will be described in detail below with reference to the block diagram of FIG. 5 and the flowchart of FIG.

Since the two-component developer contains a magnetic carrier and a non-magnetic toner as main components, when the toner concentration of the developer t (the ratio of the weight of the toner particles to the total weight of the carrier particles and the toner particles) changes, the magnetic carrier and the non-magnetic toner are changed. The apparent magnetic permeability changes depending on the mixing ratio of. The control unit 100 as the control unit acquires the information on the apparent magnetic permeability from the inductance detection sensor 32 (S1). As shown in FIG. 4, the detection output (Vsig) changes substantially linearly according to the toner density (T/D ratio). That is, the detection output of the inductance detection sensor 32 corresponds to the toner concentration of the two-component developer existing in the developing device 4a.

That is, as the toner concentration increases, the proportion of non-magnetic toner in the developer increases, so the apparent magnetic permeability of the developer decreases and the detection output decreases. On the contrary, when the toner concentration is low, the apparent magnetic permeability of the developer is high, and the detection output is high. In this way, it becomes possible to detect the toner concentration of the developer using the inductance detection sensor 32.

The detected Vsig is recorded in the memory tag 101 attached to the developing device 4a. Next, the control unit 100 compares the detected Vsig with the initial reference signal Vref (S2), (S3), and determines the toner replenishing amount by the toner replenishing means based on the calculation result of the difference (Vsig-Vref) between them. Yes (S4). The toner replenishment amount A can be obtained, for example, from the following equation 0. In addition, a is a constant.
A[g]=(Vsig−Vref)×a...(0)
Since the initial reference signal Vref is an output value corresponding to the initial state of the developer, that is, the initial toner density, Vsig is controlled so as to approach the initial reference signal. The initial reference signal Vref is determined by the initial operation of the developing device described later.

For example, in the case of Vsig-Vref>0, the toner concentration of the developer is lower than the target toner concentration, so the required toner replenishment amount is determined according to the magnitude of the difference. Therefore, the larger the difference between Vsig and Vref, the more toner is replenished. When Vsig−Vref≦0, the toner density is higher than the target, so toner supply is stopped and the toner density is lowered by toner consumption by the image forming operation. The toner replenishment control is performed as described above.

(Initial operation)
If the structure is bufferless and the movable shutter opening/closing locking member is not used, if the installation procedure is mistaken and the toner container is installed before the initial operation of the developing device, toner will leak to the developing device. As a result, the image density may change.

In this embodiment, the initial operation is performed when the developing device is new. The initial operation includes an operation (sensor adjustment) of determining an output voltage as a control target by storing the output value of the inductance detection sensor 32 in a state where the developer is new and the toner concentration is known in advance. .. By performing the sensor adjustment, the individual difference (detection error) of the inductance detection sensor 32 can be suppressed. Further, the toner density target value (reference value) to be controlled can be set correctly.

On the other hand, when the toner container is attached before the sensor adjustment, the toner flows into the developing device 4, so that the toner density becomes higher than the toner density which is known in advance. If the initial operation is performed in this state, the toner concentration target value to be controlled becomes inaccurate, and the product performance cannot be satisfied. Therefore, when the inflow of the toner is detected, the toner corresponding to the inflow amount is discharged to control the toner concentration target value to be accurate.

In this embodiment, an initial operation when all the developing devices 4a, 4b, 4c and 4d are new when the main body apparatus is shipped and installed will be described with reference to the flowchart of FIG.

In the memory tag 101, a nominal value diffminVref for obtaining the threshold value minVref from the initial output value Vsig0 and the maximum number of retries are stored in advance. The memory tag 101 has an area for storing the detection output (Vsig), the previous detection output (PrevVsig), the minimum value (minVref) that Vref can take, the maximum number of retries, the number of execution retries, and the control voltage Vout.

The power of the main body device is turned on (S11), and the control unit 100 determines whether or not the power is on for the first time after shipment (S12). If the power is on for the first time, the initial operation is executed.

When the execution of the initial operation is started, the control unit 100 first obtains the detection output Vsig0 from the inductance detection sensor 32 (S13) and obtains the threshold value minVref by the equation (1). The threshold value minVref is stored in the memory tag 101.
minVref=Vsig0-diffminVref (1)
When the detection output Vsig detected by the inductance detection sensor 32 before the initial operation is smaller than the minVref calculated by the equation 1, it is determined that the inductance detection sensor 32 is out of order or there is inflow toner. However, minVref may be stored in the memory tag 101 as a fixed value.

Next, the CPU 107 causes the developing drive motor 103 to rotate the stirring screws 28 and 29 for 2 minutes and 30 seconds (S14). By rotating the stirring screws 28 and 29, the toner concentration distribution of the developer in the developing device 4 is leveled, and the charge amount of the toner in the developing device 4 is increased. Then, the CPU 107 obtains the detection output Vsig from the inductance detection sensor 32 after uniformizing the toner concentration distribution of the developer (S15), and stores the detection output Vsig in the memory tag 101. At this time, if the previous detection output is already stored in the memory tag 101, the previous detection output is held as the previous detection output (PrevVsig). The memory tag 101 stores the old detection output in another area each time a new detection output is stored. When a predetermined number or more of detection outputs are stored, the memory tag 101 is deleted in order from the oldest detection output.

FIG. 9A illustrates a change in the detection output of the inductance detection sensor 32 in S14 when the toner does not flow into the developing device. As the developing drive motor 103 rotates, the charge amount of toner rises, so the detection output gradually decreases.

FIG. 9B shows a change in the detection output of the inductance detection sensor 32 in S14 when the toner flows into the developing device. When there is toner that has flowed in from the toner inlet 33, the detection output sharply decreases, and therefore changes different from those in FIG. 9A are shown.

After obtaining the detection output Vsig of the inductance detection sensor 32 in S15, the control unit 100 compares the detection output Vsig with the threshold value minVref, and when the current output value Vsig is less than the threshold value (Yes in S16), turns on the developer toner inflow flag. (S17).
Vsig<minVref (2)
Next, when the state of the toner inflow flag of the developing device is ON (Yes in S18), the control unit 100 determines whether the toner discharging process is necessary (S19). In step S19, the control unit 100 determines that the toner discharge process is necessary when the current retry count is less than the maximum retry count and the current detection output Vsig has converged to minVref. Here, for example, when the following three expressions are satisfied, the current detection output Vsig has converged to minVref.
Vsig-PrevVsig>α...(3)
Here, the threshold value α is the minimum change amount of the detection output of the inductance detection sensor 32 due to the toner discharge. The threshold value α is, for example, 0.05V.

When it is determined that the toner discharge is necessary (Yes in S19), the control unit 100 discharges the toner, updates the execution retry count stored in the memory tag 101, and turns off the developing device toner inflow flag (S20). .. However, at the first time, the toner is discharged unconditionally.

The toner is discharged by forming a pattern image. The control unit 100 rotates the developing sleeve 21 and applies a developing bias to the developing sleeve 21, thereby causing the toner to fly onto the photosensitive drum 2a. This required time is 8 seconds. Here, the time for causing the toner to fly is the time for discharging the toner flowing from the toner container T into the developing device 4 from the developing device. The toner attached to the photosensitive drum 2a is collected by the photosensitive drum cleaning device 6a.

The control unit 100 repeats the above-described detection and discharge processing (S14 to S20) so that the detection output Vsig converges within the range that Vref can take, the toner concentration becomes appropriate, and the initial reference signal and the control voltage of the inductance detection sensor 32 are set. Is possible.

When the toner inflow flag of the developing device is OFF (No in S18), the initial reference signal Vref and the control voltage Vout of the inductance detection sensor are set (S21). In FIG. 8, the specific setting of the initial reference signal Vref is performed as follows. First, the control unit 100 detects the detection output Vsig while gradually changing the control voltage Vout of the inductance detection sensor 32, and sets the control voltage Vout such that the output becomes about 2.5V. The detection output Vsig at the set control voltage Vout is set as the initial reference signal Vref. The set initial reference signal Vref and control voltage Vout are sent to the memory tag 101 and stored therein. At this point, a series of initial operations are completed, and printing is ready.

On the other hand, if it is not determined in step S19 that the toner ejection is necessary (No in S19), the control unit 100 displays an error screen on the liquid crystal display of the display unit 102 (S22).

By performing the initial operation of the developing device by the above control, a bufferless structure and a movable shutter opening/closing locking member structure are not adopted, and an unexpected procedure that is not according to the installation procedure manual is performed. Even when installed in, the fluctuation of the image density can be suppressed.

T toner container 4a developing device 32 inductance detection sensor 107 CPU
221 toner container detection sensor 604 toner container drive motor

Claims (3)

An image forming apparatus in which a container containing toner is removable,
An image forming means having a developing device for accumulating a developer containing the toner, and forming an image using the toner of the developing device;
A mounting part on which the storage container is mounted,
Replenishing means for replenishing the toner from the container attached to the attachment portion to the developing device,
An inductance detection sensor which is provided in the developing device, detects the magnetic permeability of the developer in the developing device, and outputs an output value based on the detection result,
Replenishment control means for controlling the replenishment means based on the output value and the reference value of the inductance detection sensor,
And a control unit that performs an initial operation including sensor adjustment for setting the reference value based on the output value of the inductance detection sensor,
The control means determines whether or not the toner is supplied from the container to the developing device before the sensor adjustment is performed in the initial operation, and the container before the sensor adjustment is performed. When the toner is supplied from the developing device to the developing device, a toner image is discharged from the developing device by forming a pattern image by the image forming unit, and the toner discharging process is performed. An image forming apparatus, wherein the sensor adjustment is performed later. The control means acquires the output value of the inductance detection sensor before the sensor adjustment is performed, and executes the toner discharge process if the acquired output value is less than a threshold value. Item 1. The image forming apparatus according to Item 1. The control means acquires the output value of the inductance detection sensor again after the toner discharge processing is executed, and repeatedly executes the toner discharge processing until the acquired output value becomes less than the threshold value. The image forming apparatus according to claim 2, wherein:

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