JP2001242690A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device where any abnormality in rotation of a toner agitating means can be detected without providing an exclusive sensor. SOLUTION: In the device, an electrostatic latent image formed on an image carrier 302 is developed by toner, the toner agitating means 305 is provided in a toner container 308 and the toner is agitated and carried to a developing means 304 by rotating the toner agitating means 305 at a specified rotating cycle. Furthermore, a multiple number of electrodes 306 and 307 are provided faced to each other inside the toner container 308 and any abnormality in the toner agitating means 305 is detected based on width of variation of electrostatic capacity between the multiple number of electrodes that are varied periodically due to rotation of the toner agitating means 305.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus, and more particularly, to an abnormality detection of a toner stirring means provided in a toner container for storing a toner for developing an electrostatic latent image.

[0002]

2. Description of the Related Art Conventionally, in an electrophotographic image forming apparatus in which an electrostatic latent image is formed on an image carrier and then the electrostatic latent image is developed with toner, the image carrier and charging means are used. A configuration in which a process cartridge in which a developing unit, a cleaning unit, and a toner container are integrated is mounted on an image forming apparatus main body is widely used.

FIG. 10 is a view showing the structure of such a conventional process cartridge. In FIG.
Is a process cartridge, 102 is a photosensitive drum as an image carrier, 103 is a charging roller as charging means, 104 is a developing sleeve as developing means, 105 is a cleaning device as cleaning means, and 106 is a toner container.

Reference numeral 107 denotes a stirring sheet provided in the toner container 106. The stirring sheet 107 rotates in the toner container 106 at a predetermined rotation cycle, and is stored in the toner container 106 (not shown). This is for stirring the toner. By agitating the toner in this manner, the conveyance of the toner in the direction of the developing sleeve is promoted, and all the toner in the toner container 106 can be supplied to the developing sleeve 104.

On the other hand, in FIG. 1, reference numerals 108 and 109 denote first and second antenna electrodes provided for sequentially detecting the amount of toner in the toner container 106. The first and second antenna electrodes 108 and 109 are provided. Is connected to a capacitance detecting device provided in an image forming apparatus main body (not shown).

Here, since the material constituting the toner has a higher dielectric constant than that of air, the capacitance between the first and second antenna electrodes 108 and 109 is smaller than that of the air. , 109 in accordance with the amount of toner distributed. Therefore, if the capacitance between the first and second antenna electrodes 108 and 109 is detected, and the detected capacitance is compared with a predetermined value corresponding to the toner amount by the capacitance detection device. , The amount of toner in the toner container 106 can be sequentially detected.

[0007]

In such a conventional image forming apparatus, when an abnormality occurs in the stirring device, the rotation of the stirring sheet 107 becomes abnormal, and the toner supply to the developing sleeve 104 is stopped. There is a problem that the recording image becomes insufficient and an abnormality occurs in the recorded image.

In order to prevent this problem, for example, a dedicated sensor for detecting the rotation state of the stirring sheet 107 is provided in the process cartridge 101, and when it is detected that the stirring sheet 107 is not rotating normally,
Notify the user of the abnormality of the process cartridge 101,
In some cases, replacement of the process cartridge 101 is prompted. However, in such a method, it is necessary to add a sensor in the process cartridge 101, which leads to an increase in the cost of the process cartridge 101.

The present invention has been made in view of such circumstances, and provides an image forming apparatus capable of detecting an abnormal rotation of a stirring sheet (toner stirring means) without providing a dedicated sensor. It is intended for.

[0010]

SUMMARY OF THE INVENTION The present invention provides an image carrier on which an electrostatic latent image is formed, developing means for developing the electrostatic latent image with toner, and toner for storing the toner used for the development. In the image forming apparatus provided with a container, provided in the toner container, a toner stirring unit that rotates at a predetermined rotation cycle to stir the toner stored in the toner container, and transports the toner to the developing unit; An abnormality of the toner stirring means is determined based on a plurality of electrodes provided to face the inner surface of the toner container and a fluctuation width of a capacitance between the plurality of electrodes periodically fluctuated by rotation of the toner stirring means. Abnormality detecting means for detecting the abnormality.

Further, according to the present invention, the variation width of the capacitance between the antenna electrodes is a difference between a maximum value and a minimum value of the capacitance within a predetermined measurement period, and An abnormality of the toner stirring means is detected by comparing the width with a predetermined reference value.

Further, the present invention is characterized in that the predetermined reference value is set corresponding to a maximum value or a minimum value of the capacitance within the predetermined measurement period. .

Further, in the present invention, the measurement cycle of the capacitance is longer than the rotation cycle of the toner stirring member.

Further, the present invention is characterized in that a display means for displaying an abnormality of the toner stirring means is provided.

Further, the invention is characterized in that the plurality of electrodes are provided in a toner remaining amount detecting means for detecting a remaining amount of toner in a toner container based on a capacitance between the electrodes. Things.

Further, the present invention is characterized in that a display means is provided for displaying an abnormality of the process cartridge having the image carrier, the developing device and the toner container when an abnormality of the toner stirring means is detected. It is.

Further, the present invention is characterized in that when the minimum value of the capacitance is smaller than a predetermined value, the abnormality of the toner stirring means is not detected.

Further, the present invention is characterized in that an abnormality of the toner remaining amount detecting means is detected based on a minimum value of the capacitance between the electrodes.

Further, as in the present invention, the electrostatic latent image formed on the image carrier is developed with toner, and the toner container is provided with toner stirring means, and the toner stirring means is rotated at a predetermined rotation cycle. Thus, the toner is stirred and transported to the developing unit. In addition, a plurality of electrodes are provided on the inner surface of the toner container so as to face each other, and based on a fluctuation width of the capacitance between the plurality of electrodes that periodically fluctuates due to the rotation of the toner stirring means, the abnormality detecting means detects the toner stirring means. Try to detect abnormalities.

[0020]

Embodiments of the present invention will be described below.

FIG. 1 is a diagram showing a schematic configuration of an image forming apparatus according to a first embodiment of the present invention.
200 is an image forming apparatus, 203 is a recording paper tray, 215
Denotes a toner container 308, a charging device 303, a developing sleeve 304 as a developing unit, and a photosensitive drum 302 as an image carrier.
Is a scanner unit.

The image forming apparatus 2 having such a configuration
00, when an image is formed on the recording paper 214,
First, a laser beam from a laser light source 211 in a scanner unit 217 is irradiated onto a photosensitive drum 206 charged on a surface photosensitive member by a charging device 303 via a rotating polygon mirror 212 and a reflecting mirror 213. Then, an electrostatic latent image is formed on the surface of the photosensitive drum 206. After that, the electrostatic latent image is subjected to a developing process by the developing sleeve 304 to form a toner image on the photosensitive drum.

In addition, after the recording paper 214 set on the recording paper tray 203 is sent out from the recording paper tray 203 by driving the pickup roller 205 in parallel with the toner image forming operation, the paper Is conveyed toward the registration roller 207 in the direction of arrow A. Thereafter, the photosensitive drum 302 and the transfer roller 2 are driven at a predetermined timing by driving the registration roller 207.
08 and the photosensitive drum 302 on the recording paper.
Is transferred to the toner image.

Next, the recording paper 214 onto which the toner image has been transferred in this manner is conveyed to a pair of fixing rollers 209, and heated and pressed by the pair of fixing rollers 209 to fix the toner image on the recording paper. After that, the sheet is conveyed out of the image forming apparatus main body 201 by the sheet discharging roller 210, and a series of recording processing ends. These series of processes are controlled by a controller 400 shown in FIG. 3 described later.

FIG. 2 shows the process cartridge 2
15 is a diagram illustrating a configuration of a stirring sheet 305. In the same drawing, reference numeral 305 denotes a stirring sheet which is a toner stirring means rotatably disposed in the toner container 308.
Is mounted around a metal rod 309 that is rotationally driven by a driving device (not shown) provided in the image forming apparatus main body 201. The metal rod 309 is rotated at a predetermined cycle in the direction of arrow A by the rotation of the metal rod 309. It has become. In the present embodiment, the rotation cycle of the stirring sheet 309 is 10 seconds.

The rotation of the stirring sheet 305 causes the toner (not shown) contained in the toner container 308 to be stirred, and the toner is transferred to the developing sleeve 3.
04. The stirring sheet 3
05 (metal rod 309) is also transmitted to a drive unit that drives the photosensitive drum 302, the developing sleeve 304, and the like, whereby all the devices of the process cartridge 215 are synchronized. It is designed to be driven.

On the other hand, in the figure, reference numerals 306 and 307 denote a first antenna electrode and a second antenna electrode provided for sequentially detecting the amount of toner in the toner container. , 307 are installed facing the inner surface of the toner container 308.

As described above, the dielectric constant of the material constituting the toner is higher than that of air, and the first and second materials are different.
Since the capacitance between the two antenna electrodes changes according to the amount of toner distributed between the antenna electrodes 306 and 307, the capacitance between the first and second antenna electrodes 306 and 307 is detected. Thus, the amount of toner in the toner container can be detected.

Therefore, the first and second antenna electrodes 306 and 307 are set so as to sequentially detect the amount of toner in the toner container.
As shown in FIG. 3, is connected to a capacitance detecting device 401 which is a toner remaining amount detecting means provided in the image forming apparatus main body 201.

FIG. 4 shows this capacitance detecting device 40.
1 is a diagram showing a circuit configuration of a first antenna electrode 306.
Is connected to the terminal 415 of the capacitance detection device 401, the second antenna electrode 307 is connected to the terminal 414, and for example, the oscillation circuit 402 is connected to the first antenna electrode 306.
Is applied. In the present embodiment, this clock signal has an amplitude Vc1 of 24 V and a frequency fc1 of 100 KHz, and the oscillation circuit 402 is provided by the controller 4 shown in FIG.
When the control signal CLKON signal (LOW level signal) from 00 is input, an output state is set.

Here, when a clock signal is applied to the first antenna electrode 306, the second antenna electrode 307 has a capacitance corresponding to the magnitude of the capacitance Ct due to the capacitance Ct formed between the two antennas. AC current It flows. Then, this AC current It is input via a diode 407 to an integrating circuit composed of a resistor 412 and a capacitor 411, whereby a DC voltage Vt corresponding to the AC current is generated between the capacitors 411. Note that this DC voltage V
t is represented by the following equation.

Vt = α × Vc1 × fc1 × Ct (where α is a predetermined constant) On the other hand, in FIG.
The constant of the reference capacitor 403 is set to the same value as the capacitance when there is no toner between the antenna electrodes.
A clock signal output from the oscillation circuit 402 is applied to the reference capacitor 403 in the same manner as the first antenna electrode 306. An AC current Iref flowing by the clock signal passes through the diode 404, 409 and a capacitor 411 are input to an integrating circuit. The constants of the resistor 409 and the capacitor 410 are the same as those of the resistor 412 and the capacitor 411.

A reference voltage circuit 408 generates a DC voltage of 4.5 V. Therefore, a voltage Vr in which 4.5 V from the reference voltage circuit 408 and a DC voltage corresponding to the AC current Iref are superimposed is generated between the capacitors 410. The voltage Vr is represented by the following equation.

Vr = α × Vc1 × fc1 × Cref +
4.5 (where α is a predetermined constant) On the other hand, these two integrating circuits are connected to an operational amplifier 418. The output voltage Vs of the operational amplifier 418 is expressed by the following equation.

Vs = Vr−Vt = 4.5−α × Vc1 ×
fc1 (Ct−Cref) That is, the output voltage Vs of the operational amplifier 418 is a voltage corresponding to the difference between the capacitance Ct between the antenna electrodes and the capacitance of the reference capacitor Cref. And this operational amplifier 4
18 via an output terminal 417 of the capacitance detection device 401 as shown in FIG.
0 is input to an analog-to-digital conversion terminal (not shown).

FIG. 5 shows a toner amount detection voltage detected by the controller 400 based on the output voltage Vs from the capacitance detection device 401 when a toner stirring device (not shown) for driving the stirring sheet 305 is driven. Vs 'indicates a time change, and the toner amount detection voltage Vs' periodically changes as shown in FIG. This is a stirring sheet 3
This is because the toner distribution between the antenna electrodes changes due to 05, and the output voltage Vs of the capacitance detection device 401 changes. The toner amount detection voltage Vs' fluctuates in the same cycle as the rotation cycle of the stirring sheet 305, that is, in a cycle of 10 sec.

Here, in the present embodiment, the toner amount in the toner container is accurately detected by detecting the maximum value and the minimum value of the toner amount detection voltage Vs' that changes periodically as described above. At the same time, an abnormality of the stirring sheet 305 (toner stirring device) is detected.

Next, a series of processing methods for detecting the toner amount in the toner container from the toner amount detection voltage Vs' will be described with reference to the flowchart shown in FIG.

FIG. 6A shows the toner amount detection voltage V
5 is a flowchart showing a series of processes for detecting a maximum value and a minimum value of s'. This series of processes is performed by a central processing unit (hereinafter referred to as a CPU) in a controller. This is executed at the timing when the recording process is being performed.

First, the CPU performs initial setting of variables used in a series of processes as initial setting 1 (step 60).
2). That is, a predetermined measurement cycle for detecting the maximum value and the minimum value of the toner amount detection voltage Vs' corresponding to the maximum value and the minimum value of the capacitance, which is 15 seconds in the present embodiment.
c, resets the value Ta of the CPU internal timer A provided for measuring the
A variable Vs (max) for storing the maximum value of s' is set to 4.5V.
Is a variable V that stores the minimum value of the toner amount detection voltage Vs'.
s (min) is set to 0, respectively.

Next, the oscillation circuit 402 is driven by setting the CLKON signal to the LOW level to output a clock signal (step 603). Thereby, the capacitance detection device 4
01 operation is started. Subsequently, the internal timer A is started, and the time counting process is started (step 604).

Next, after resetting the value Tb of the CPU internal timer B provided for measuring a predetermined time, 1 second in this embodiment, as an initial setting 2 (step 605), the timer B is started. (Step 60
6). Then, after reading the toner amount detection voltage Vs' (step 609), processing 1 is executed.

In the processing 1, as shown in FIG.
First, the read toner amount detection voltage Vs' is compared with the stored maximum value Vs (max) (step 61).
3) If the toner amount detection voltage Vs' is larger than the stored maximum value Vs (max) (step 613)
Y), a process of updating Vs (max) is performed (step 614).

Next, the read toner amount detection voltage Vs'
Is compared with the stored minimum value Vs (min) (step 615), and when the toner amount detection voltage Vs' is smaller than the stored minimum value Vs (min) (Y in step 615). , Vs (min) are updated (step 616).

Next, after completing the processing 1, the timer B
It is checked whether or not the counted value Tb of the timer A exceeds 1 sec (step 609). When the counted value Tb exceeds 1 sec (Y in step 609), the counted value Ta of the timer A is counted.
Is greater than 15 seconds (step 6).
10). Then, when the counted value Ta of the timer A exceeds 15 seconds, a series of processing ends. Also, the time value T
If a is equal to or shorter than 15 seconds, the process returns to step 605 and the same processing is repeated.

FIG. 5B shows the toner amount detection voltage V
FIG. 9 is a diagram showing a change in s ′ and detection timing in the series of processes described above. First, the process is started at point A to read a toner amount detection voltage Vs ′, and then 1 second from point A.
At point B after c, the toner amount detection voltage Vs 'is read again, and after 1 second, the toner amount detection voltage Vs' is read at point C.
To read In this way, reading at 1-sec intervals is repeated continuously for 15 sec, and the reading process ends.

By such a series of processes, the maximum value Vs (max) and the minimum value Vs (mi) of the toner amount detection voltage Vs' during 15 seconds from the start of the process.
The detection of n) is completed. Here, since the fluctuation period of the detection voltage Vs is 10 seconds, by setting the measurement period longer than the fluctuation period of the detection voltage Vs, the maximum value Vs (max) and the minimum value of the toner amount detection voltage Vs ′ are reduced. The value Vs (min) can be made to correspond to the maximum value and the minimum value of the periodically fluctuating detection voltage Vs.

Next, a method for detecting the amount of toner in the toner container by using the maximum value Vs (max) and the minimum value Vs (min) of the toner amount detection voltage Vs' detected by performing the above-described processing, A method of detecting an abnormality of the stirring sheet 305 (toner stirring device) will be described.

First, a method for detecting the amount of toner in the toner container will be described. FIG. 7 is a diagram showing the relationship between the toner amount in the toner container and the toner amount detection voltage Vs'. The toner amount is defined as 100% when the toner in the toner container is full, and 0% when there is no toner in the toner container.
And

As shown in the figure, both the maximum value Vs (max) and the minimum value Vs (min) of the toner amount detection voltage Vs' that fluctuate periodically change according to the toner amount. %, Vs (max) is 4.5V. As a result, the maximum value Vs (max) or the minimum value Vs
By detecting (min), the toner amount can be detected. In the present embodiment, the detection of the toner amount is performed by using a V having a sharp characteristic curve as shown in FIG.
s (min) is used, and the detection accuracy of the toner amount is improved by using Vs (min) having such a characteristic curve.

On the other hand, the abnormality detection of the stirring sheet 305 (toner stirring device) is performed by detecting the maximum value Vs (max) and the minimum value Vs (min) of the toner amount detection voltage Vs' which fluctuate periodically as shown in FIG. Judge based on the difference.

Next, the detection of an abnormality in the stirring sheet 305 (toner stirring device) will be described with reference to the flowchart shown in FIG.

In this case, first, the difference between the maximum value Vs (max) and the minimum value Vs (min) of the toner amount detection voltage Vs 'is detected, and this is set as the amplitude ΔVs of the toner amount detection voltage Vs' (step 702). ). Here, as shown in FIG. 7, the amplitude ΔVs of the toner amount detection voltage Vs ′ changes according to the amount of toner, because the amount of toner stirred from the stirring sheet 305 changes according to the amount of toner. .

Next, a reference value ΔVref of the amplitude ΔVs is set (step 703). Here, this amplitude ΔVs
The reference value ΔVref is an amplitude value when the stirring sheet 305 becomes abnormal, and is a value stored in advance in the controller. In the present embodiment, the reference value △ Vref is set according to the minimum value Vs (min) having a steep characteristic curve so as to improve the accuracy of abnormality detection.

Next, the amplitude ΔV of the toner amount detection voltage Vs'
s is compared with the reference value 比較 Vref (step 70).
4). Here, when the amplitude ΔVs of the toner amount detection voltage Vs ′ is larger than the reference value ΔVref (step 704)
(Y), the toner is sufficiently stirred, and it is determined that the stirring sheet 305 (toner stirring device) is normal, and the process ends.

On the other hand, the amplitude ΔV of the toner amount detection voltage Vs ′
If s is smaller than the reference value △ Vref (step 7
04, N), it is determined that the toner agitation is insufficient and the operation of the agitation sheet 305 (toner agitation device) is abnormal, and "cartridge abnormality" is displayed on the operation panel 450 (step 707). The user is prompted to replace the process cartridge 215.

As described above, the agitation sheet 305 (toner agitation) is determined based on the fluctuation width of the capacitance between the plurality of electrodes that periodically fluctuates due to the rotation of the agitation sheet 305, ie, the amplitude ΔVs of the toner amount detection voltage Vs ′. Device) can be detected. Also, the stirring sheet 3
By detecting an abnormal rotation of the toner cartridge 05 (toner stirring means), it is not necessary to provide a dedicated sensor for the process cartridge 215, and the cost of the process cartridge 215 can be prevented from increasing.

By the way, the abnormality of the stirring sheet 305 (toner stirring means) is determined by the stirring sheet 305 (toner stirring means).
The clock signal may not be output or the clock signal may have an amplitude smaller than a predetermined value in the transmission circuit 402 of the capacitance detection device 401 instead of the abnormality itself.

Next, such a capacitance detecting device 401
A second embodiment of the present invention which detects an abnormality of the second embodiment will be described.

In the present embodiment, the minimum value V of the toner detection voltage Vs' that periodically fluctuates due to the stirring of the toner
By detecting s (min), abnormality detection of the capacitance detection device 401 is performed.

That is, as shown in FIG.
In the case where “the toner is 100%” where the minimum value Vs (min) of s ′ is the smallest, the value of Vs (min) is 1.0V. Therefore, the minimum value Vs (mi of the toner detection voltage Vs'
If the value of n) is 1.0 V or less, it can be determined that the clock signal is an abnormal output.

Next, such a capacitance detecting device 401
Will be described with reference to a flowchart shown in FIG.

First, the minimum value Vs (min) of the toner amount detection voltage Vs' is detected by the processing shown in the flowchart of FIG. 6 in the first embodiment described above, and thereafter, the detected toner amount Minimum value Vs of detection voltage Vs'
It is compared whether (min) is 1.0 V or less (step 902).

If Vs (min) is not less than 1.0 V (Y in step 902), the first antenna electrode 3
It is determined that the clock signal applied to the counter 06 is a normal output, and steps 903 to 905 and step 90
9, the same processing as in the first embodiment described above is performed.
The detection of the remaining amount of toner and the detection of the abnormality of the cartridge are performed.

On the other hand, when Vs (min) is 1.0 V or less (N in step 902), the first antenna electrode 30
It is determined that the clock signal applied to 6 is not normal, the cartridge abnormality is not detected, and "capacitance detection device abnormality" is displayed on the operation panel 450 (step 910).

As described above, the minimum value Vs (min) of the toner detection voltage Vs' that fluctuates periodically due to the stirring of the toner.
Is detected and compared with a predetermined value, thereby irrespective of the state of the toner stirring device in the toner container,
It is possible to accurately detect the abnormality of No. 1, particularly the abnormality of the clock signal applied to the first antenna electrode 306, and prevent erroneous detection of the abnormality detection of the toner stirring device.

[0067]

As described above, according to the present invention, the abnormality of the toner stirring means is detected based on the fluctuation width of the capacitance between a plurality of electrodes which periodically changes due to the rotation of the toner stirring means. Therefore, the rotation abnormality of the toner stirring means can be detected without providing a dedicated sensor. In addition, the cost of the process cartridge can be prevented from increasing.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a schematic configuration of an image forming apparatus according to a first embodiment of the present invention.

FIG. 2 is a diagram illustrating a configuration of a process cartridge of the image forming apparatus.

FIG. 3 is a block diagram of toner amount detection control of the image forming apparatus.

FIG. 4 is a circuit diagram of a capacitance detection device provided in the image forming apparatus.

FIG. 5 is a diagram showing a change in a toner amount detection voltage of the capacitance detection device.

FIG. 6 is a flowchart illustrating a toner amount detection processing method of the image forming apparatus.

FIG. 7 is a diagram showing characteristics of the toner amount detection voltage.

FIG. 8 is a flowchart illustrating a method of detecting an abnormality of a stirring sheet (toner stirring device) of the image forming apparatus.

FIG. 9 is a flowchart illustrating a method of detecting an abnormality in the capacitance detection device of the image forming apparatus according to the second embodiment of the present invention.

FIG. 10 is a diagram showing a configuration of a conventional process cartridge.

DESCRIPTION OF SYMBOLS 200 Image forming apparatus 201 Image forming apparatus main body 215 Process cartridge 302 Photosensitive drum 304 Developing sleeve 305 Stir sheet 306 First antenna electrode 307 Second antenna electrode 308 Toner container 400 Controller 401 Capacitance detection device 402 Oscillation circuit 450 Operation Panel

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H027 DA01 DA50 DD02 DE07 EC06 ED08 GB07 GB08 2H077 AB01 AB14 AD06 AD13 BA09 DA15 DA24 DA42 DA59 DB10 DB14 9A001 BB06 HH34 JJ35 KK37 KK42 LL09

Claims (9)

[Claims] 1. An image forming apparatus comprising: an image carrier on which an electrostatic latent image is formed; developing means for developing the electrostatic latent image with toner; and a toner container for storing toner used for the development. A toner stirring unit provided in the toner container, which rotates at a predetermined rotation cycle to stir the toner stored in the toner container, and conveys the toner to the developing unit; A plurality of electrodes provided in a predetermined manner, and abnormality detecting means for detecting an abnormality of the toner stirring means based on a fluctuation width of a capacitance between the plurality of electrodes which periodically fluctuates due to rotation of the toner stirring means. An image forming apparatus comprising: 2. The variation range of the capacitance between the antenna electrodes is a difference between a maximum value and a minimum value of the capacitance within a predetermined measurement period. 2. An image forming apparatus according to claim 1, wherein an abnormality of said toner stirring means is detected by comparing the reference value with a reference value. 3. The image according to claim 2, wherein the predetermined reference value is set in accordance with a maximum value or a minimum value of the capacitance within the predetermined measurement period. Forming equipment. 4. The image forming apparatus according to claim 2, wherein a measurement cycle of the capacitance is longer than a rotation cycle of the toner stirring member. 5. The image forming apparatus according to claim 1, further comprising a display unit for displaying an abnormality of the toner stirring unit. 6. The apparatus according to claim 1, wherein the plurality of electrodes are provided in a toner remaining amount detecting unit that detects a remaining amount of toner in a toner container based on a capacitance between the electrodes. The image forming apparatus as described in the above. 7. The display device according to claim 1, further comprising a display unit for displaying an abnormality of the process cartridge including the image carrier, the developing device, and the toner container when the abnormality of the toner stirring unit is detected. Image forming apparatus. 8. The image forming apparatus according to claim 1, wherein when the minimum value of the capacitance is smaller than a predetermined value, the abnormality of the toner stirring unit is not detected. 9. The image forming apparatus according to claim 6, wherein an abnormality of said toner remaining amount detecting means is detected based on a minimum value of capacitance between said electrodes.