JPH07311498A - Image forming method and its control method - Google Patents

Abstract

PURPOSE:To adequately inform an operator of the time for replenishing a toner container with toners in an image forming device of an electrophotographic system with which a visible image is obtd. by using a two-components developer prepd. by mixing toners and magnetic carriers. CONSTITUTION:This image forming device is provided with a developing device 4 facing an image carrying member 1 and is provided with a toner container 21 for supplying the toners to this developing device. This toner container is provided with a toner supplying screw 24, a toner agitating member 22 and a toner detecting sensor 26. The signal outputted from this toner detecting sensor 26 is inputted to a CPU 31. This CPU 31 is so set that the respective sections of the image forming device can be driven and controlled by an image forming mode and density adjusting mode, respectively. A prescribed value is accumulated and added every time the toner detecting sensor detects 'toner absence' under prescribed conditions in these modes. A warning signal is then outputted by comparison with the reference value. The accumulated and added value is stored in a storage device 32 and is maintained even at the time of mode shifting and on/off of a power source.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic image forming apparatus which obtains a visible image by using a two-component developer in which a toner and a magnetic carrier are mixed, and in particular, the toner replenishment time is properly set. The present invention relates to an image forming apparatus that can be notified and a control method thereof.

[0002]

2. Description of the Related Art Conventionally, an electrophotographic image forming apparatus which visualizes an electrostatic latent image by using a two-component developer has been widely known. In such an image forming apparatus, a developing device provided facing the photoconductor is provided with a developing roll having a magnet built in, and a magnetic brush in which magnetic carriers are connected in a spike shape is formed on the peripheral surface of the developing roll to rotate the magnetic brush. Driven. Then, the toner adhering to the magnetic carrier is transferred to the photoconductor at a position where the magnetic brush comes into contact with or comes close to the photoconductor to visualize the latent image. Therefore, since only the toner is consumed from the developer accommodated in the developing device, it is known that the toner container is provided at a position close to the developing device to replenish the toner.

Replenishment of toner from the toner container to the developing device is carried out in accordance with the consumption of the toner, and is controlled so that the toner concentration of the developer in the developing device is always substantially constant. This is because the density of the visualized toner image becomes insufficient when the toner density decreases, and the toner image becomes excessively dark when the toner density becomes too high.

Further, there has been proposed a means for displaying a warning that the toner should be replenished from the outside of the apparatus when the toner in the toner container is low or empty. For example, in the toner replenishment control means disclosed in Japanese Patent Laid-Open No. 63-2138878, a toner concentration sensor is provided in the developing device, and the toner concentration sensor detects the toner concentration of the developer in the developing device. Therefore, when it is detected that the toner concentration has decreased, the toner is replenished from the toner hopper (toner container), and when the toner concentration exceeds a predetermined value, the replenishment operation is stopped. When the toner concentration does not increase even after the toner replenishing operation is continued for a predetermined time, the toner replenishment is stopped and the operator is made aware that the toner in the toner hopper is empty.

However, in such a toner replenishment control method, when the toner concentration in the developing device does not rise, it is recognized that the toner in the toner hopper is empty, so that the operator can replenish the toner. By the time we knew it was necessary, we were in a state where we could hardly obtain an image with appropriate density. Therefore, there is a problem that a good image cannot be formed until the replenishment toner is prepared.

On the other hand, as an image forming apparatus which does not cause the above problems, there is one which detects the remaining amount of toner in a toner container storing toner. This is disclosed in, for example, Japanese Patent Laid-Open No. 4-246672, and uses a toner container and a developing device as shown in FIGS. 6 and 7. This developing device has two developing rolls 4a,
4a and an agitation supply member 4b for supplying the developer to these developing rolls, and the housing 4c contains the two-component developer. The toner container 21 includes the toner stirring member 2
2 and 23, a toner supply screw 24 (toner supply means) for conveying the toner toward the discharge port, and a toner sensor 26 mounted on the wall surface, and a toner supply pipe 27.
The toner is supplied to the developing device 4 through.

In such a toner container 21, when a sufficient amount of toner is stored, the toner sensor 26 outputs a signal indicating "toner present" (state shown in FIG. 8), but from the discharge port. When the toner is supplied to the developing device 4 and the amount of the toner decreases, a time period in which the toner is not in contact with the sensor surface appears due to stirring, and during this time, the toner sensor outputs a signal indicating “no toner”. Output. This time first appears for a short time, then for a while a signal indicating "with toner" is output or "without toner"
There is a period during which a signal indicating is output (state shown in FIG. 8). Then, the time for outputting the "toner-less" signal gradually increases, and when the toner further decreases, the toner sensor continuously outputs the "toner-less" signal (state shown in FIG. 8). However, at this time, the toner remains on a part of the bottom of the toner container, which does not affect the image formed immediately, and when the toner supply operation to the developer is continued, The toner in the container becomes empty (state shown in FIG. 8). In the above process, when the toner sensor starts outputting the "toner-less" signal, it is not necessary to output the toner replenishment warning signal yet, and from this time until the toner container becomes empty A toner replenishment warning signal will be output at that time.

[0008]

However, in the image forming apparatus having the toner container as described above, it is not possible to properly display the time when the toner should be replenished into the toner container based on the output of the toner sensor. It's not easy.
In other words, as described above, the toner sensor output gradually increases in time for outputting the "toner-less" signal as the toner decreases, and even if the "toner-free" signal is continuously output, the toner container is still output. A small amount of toner remains inside, and in such a state, it is not possible to accurately detect the toner consumption amount only from the output of the toner sensor.

In addition to the image forming mode in which the image forming apparatus develops and transfers the image formed on the photoconductor, a density adjusting mode in which the toner density in the developing apparatus is increased or decreased in order to adjust the image density. In this case, the toner is supplied from the toner container to the developing device in each mode, and it becomes more difficult to judge the remaining amount of toner in the toner container from the output of the toner sensor. That is, the mode of toner supply from the toner container to the developing device is significantly different between the image forming mode and the density adjustment mode, and in the image forming mode, the toner is gradually supplied according to the consumption of the toner, whereas in the density adjustment mode. A lot of toner is supplied to the developing device in a short time. Therefore, the toner sensor is "no toner"
If the above two modes are switched after outputting the signal or outputting the "toner present" signal, it is not possible to evaluate the toner consumption in these modes only from the output of the toner sensor. However, there is a problem in that a warning that toner should be supplied cannot be properly displayed.

The present invention has been made in view of the above circumstances, and when the toner in the toner container is reduced even if the image forming mode and the density adjusting mode are arbitrarily selected and executed. An object of the present invention is to provide an image forming apparatus and a control method thereof that can appropriately display a warning to the operator that there is no toner.

[0011]

In order to solve the above problems, the invention according to claim 1 is an image carrier capable of forming a latent image on the surface due to a difference in charging potential. Using a two-component developer containing toner and carrier,
A developing device for transferring the toner to the image carrier to visualize the latent image, a toner container for containing the toner to be supplied to the developing device, a toner stirring unit provided in the toner container, and the toner container In an image forming apparatus having a toner detection sensor provided in the vicinity of the bottom of the developing device, an image forming mode in which a toner image is formed on the image carrier and the toner image is transferred to a transfer material. Mode selection means for selecting a density adjustment mode for adjusting the density of a toner image by adjusting the toner density of the developer contained therein, transition between the two modes, and the image carrier for each mode. Control means for controlling the operation of the developing device; and the toner under predetermined conditions in the operation of the developing device or the operation of supplying toner to the developing device. Each time the detection sensor detects that there is no toner, the mode at the time of detection cumulatively adds the values set individually by either of the above two modes, and compares the cumulative addition value with the preset reference value. And a storage unit that stores the cumulative addition value and that can maintain the cumulative addition value during mode transition and power ON / OFF, wherein the control unit controls the cumulative addition value. Is set to the reference value, or becomes equal to or more than the reference value, the toner replenishment warning signal is set to be output.

According to a second aspect of the present invention, in the image forming apparatus according to the first aspect, when the mode selected by the control means at the time of outputting the toner replenishment warning signal is a density adjustment mode. Is set to suspend the density adjustment operation and prohibit the transition to the density adjustment mode when the selected mode is the image forming mode.

According to a third aspect of the control method of the image forming apparatus, an image carrier capable of forming a latent image due to a difference in charging potential on the surface, and a two-component developer including a toner and a carrier are used, A developing device for transferring the toner to the image carrier to visualize the latent image, a toner container for containing the toner to be supplied to the developing device, a toner stirring unit provided in the toner container, and the toner container An image forming mode for forming a toner image on the image carrier and transferring the toner image onto a transfer material; and a toner detection sensor provided in the vicinity of the bottom of the developing device. One of a density adjustment mode for adjusting the density of the toner image by adjusting the toner density of the developer is selected, and the movement of the image carrier and the developing device is selected for each mode. A method for controlling an image forming apparatus, wherein each time the toner detection sensor detects the absence of toner under a predetermined condition in the operation of the developing apparatus or the operation of supplying toner to the developing apparatus, The mode cumulatively adds the values set separately by either of the above two modes, compares the cumulative added value with a preset reference value,
When the cumulative addition value becomes the reference value or becomes equal to or more than the reference value, a toner replenishment warning signal is output,
When the cumulative addition value does not exceed the reference value, the cumulative addition value is stored, and when the mode is changed and when the power is turned on.
A step of maintaining the cumulative addition value even when N / OFF is included.

In the invention described in claim 1 or 3, the toner container is communicated with the developing device, and the toner can be supplied to the developing device as the toner in the developing device is consumed. It is a thing. The toner stirring means is driven in the toner container and stirs so that the entire amount of the toner can be discharged without staying therein, and the structure and shape thereof can be appropriately designed. The toner sensor can output a "toner present" signal when the toner is in contact with the detection surface and a "toner absent" signal when the toner is not in contact. For example, there is a sensor using a piezoelectric element. .

In the above-mentioned claim 1 or claim 3,
The "predetermined condition in the operation of the developing device or the operation of supplying the toner to the developing device" means, for example, the condition that the developing bias is applied, the condition that the developing roll is driven, and the latent amount for one sheet of paper. The condition that the operation that consumes the toner is performed, such as the condition that the image is developed,
It refers to the condition that the toner supply member that sends toner from the toner container to the developing device is being driven. If the toner sensor detects "no toner" under any of these conditions, the set value is cumulatively added. To do. The mode selection means is not limited to one that can select one of the image forming mode and the density adjustment mode and cannot select any other mode, and may be one that can select other modes.

[0016]

In the image forming apparatus according to the first aspect, the toner is stirred by the toner stirring means in the toner container, and at the same time, the toner sensor detects the presence or absence of the toner. At this time, as shown in FIG. 8, the output of the toner sensor starts to output the "toner-less" signal as the toner decreases, and gradually the time for outputting the "toner-less" signal becomes longer. The time when this "toner-less" signal is first output and the time when each toner-free signal is output vary greatly depending on the flow state of the toner, etc., and it is not reliable enough. Each time the toner sensor detects "no toner" under the condition that the operation to consume or the operation corresponding to this is performed, the preset value is cumulatively added. This corresponds to the toner consumption amount, and by comparing the cumulative addition value with the reference value, it is possible to accurately recognize that the toner remaining amount in the toner container has reached the predetermined amount. Further, since the cumulative added value is stored in the storage means and the stored value can be maintained even when the mode is changed or the power is turned on / off, the power is turned on.
Even if the status of supplying toner from the toner container to the developing device changes due to N / OFF or mode switching, this is accurately recognized when the amount of toner in the toner container has decreased to a predetermined value, and appropriate It is possible to issue a toner replenishment warning signal at any time.

In the image forming apparatus according to the second aspect, when the mode selected at the time of outputting the toner replenishment warning signal is the density adjustment mode, the density adjustment operation is interrupted and the selected mode is the image. Since it is set to prohibit the transition to the density adjustment mode when in the formation mode, a large amount of toner may be consumed after the toner remaining amount in the toner container becomes low. Not done Therefore, the state in which image formation is possible can be maintained for a long time until new toner is replenished in the toner container, and the state in which image formation cannot be performed can be avoided as much as possible. In the method of controlling the image forming apparatus according to the third aspect, the same steps as the operation of the image forming apparatus according to the first aspect can be performed, and the same operation and effect can be obtained.

[0018]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic configuration diagram showing a copying machine which is an embodiment of the invention described in claim 1 or 2. This copying machine includes a belt-shaped image carrier 1 on the surface of which a latent image due to a difference in charging potential is formed by image light irradiation, and a charger 2 which uniformly charges the image carrier around the belt-shaped image carrier 1. , A patch generator 3 that forms a latent image of a preset pattern
A developing device 4 for transferring the toner to the latent image formed on the image carrier 1 to visualize it, a pre-transfer charger 5 for adjusting the charge amount of the toner before transferring the toner image, and a toner adhesion. The density sensor 10 for detecting the density of the toner image formed by the above, the transfer charger 6 for transferring the toner image onto the paper carried in from the paper conveying path 16, and the paper on which the toner image is transferred for the image carrier 1 Peeling charger 7 for peeling off the image carrier, a cleaning device 8 for cleaning and removing the toner remaining on the image carrier 1 after transfer, and a charge removal exposure for exposing the image carrier and removing the charge remaining after the transfer. And a lamp 9.

Further, as a scanning optical system for irradiating the image bearing member 1 with image light, a document exposure lamp 11, a mirror 12 and a document size detection sensor 14 are provided on a carriage 13 which moves under the platen glass 14. An original exposure device equipped with and is provided. Further, a CPU 31 for controlling the operation of each of the above parts, a storage device 32 capable of writing data, rewriting a stored value and maintaining the stored value even when the power is turned on / off, and an operator Various signals such as a selection signal can be input, and an operation unit 39 on which information necessary for operation is displayed is provided.

The developing device uses a two-component developer in which a magnetic carrier and toner are mixed, and is the same as the developing device shown in FIG. This developing device has two developing rolls 4a and a stirring supply member 4b, and has a power source 38
The developing bias is applied to the developing roll 4a from the above, and the developing roll 4a and the stirring and supplying member 4b are rotationally driven. These drives are performed based on a control signal output from the CPU 31 via the D / A converter 34. Also,
This developing device 4 has the same toner container 2 as that shown in FIG.
The toner container includes a toner stirring member 2
2, 23, a toner supply screw 24, a motor 25 for driving the toner supply screw, and a piezoelectric toner sensor 26 mounted on the wall surface of the toner container. This toner sensor outputs a "toner present" signal when toner is in contact with the toner detection surface, and "toner is absent" when toner is not in contact
A signal is output, and the output signal is the A / D converter 3
3 is input to the CPU 31.

At least the image forming mode and the density adjusting mode are set in the CPU 31, and the operation of each part of the copying machine is controlled in the selected mode. Further, the CPU 31 is set to perform a calculation for evaluating the remaining amount of toner based on a signal input from the toner sensor 26, and also has a function as a calculation unit. The operation unit 39 is provided with a display device, a ten-key pad, a mode selection button, and the like so that a signal necessary for operation can be input. By operating the mode selection button, the image forming mode or the density adjustment mode is selected. It can be switched. In FIG. 1, reference numeral 37 is an amplifier for amplifying the output signal from the concentration sensor, and reference numerals 35 and 36 are interfaces for inputting a signal to the CPU 31 or outputting a signal from the CPU 31, respectively.

In such a copying machine, when the image forming mode is selected and the operation is started, the original exposure device 40 is selected.
Exposes and scans the document surface to guide the reflected light to the image carrier 1.
At the same time, the image carrier 1 is driven and uniformly charged by the charger 2, and then the image light from the document exposing device is irradiated. As a result, a latent image is formed, and toner is attached by the developing device 4 to form a toner image. At this time,
Since the toner is consumed from the developer in the developing device, the consumed toner is replenished from the toner container 21. After the charge is adjusted by the pre-transfer charger 5, the toner image is brought into close contact with the sheet carried in from the sheet conveying path 16 and transferred onto the sheet by the transfer device 6. The sheet is peeled from the image carrier 1 by the peeling charger 7 and sent to a fixing unit (not shown). After the toner image is transferred, the image carrier 1 is irradiated with the static elimination exposure lamp 9, and then the cleaning device 8 removes the residual toner. By such a process,
A transfer image is obtained.

On the other hand, when the density adjustment mode is selected and the operation is started, the driving of the image carrier 1 and the uniform charging by the charger 1 are started, and the image light corresponding to the preset reference pattern image is generated. Is irradiated. The latent image formed in this way is developed by the adhesion of toner, and the density sensor 10
The density of the toner image is detected by. This detection signal is input to the CPU 31 via the amplifier 37 and compared with a preset target range. When it is determined that the density is too high by such density detection operation,
The operations of the image carrier 1 and the charger 2 are continued, and the image light corresponding to the high density pattern image for toner consumption is irradiated. By developing this latent image, the toner in the developing device 4 is consumed and the toner density of the developer is reduced. The toner image formed on the image carrier 1 is collected by the cleaning device 8 without being transferred to a sheet. Further, when it is determined that the density is too low, the toner supply screw 24 of the toner container 21 is driven, the toner is replenished in the developing device 4, and the toner concentration of the developer in the developing device 4 increases. To do.

Next, a toner detection operation when the copying machine is used in the image forming mode or the density adjusting mode, which is an embodiment of the invention described in claim 3, will be described with reference to FIG. Explain. First, Ts stored in the storage device 32 at the beginning of the operation such as when the power of the copying machine is turned on.
The current value of, that is, a value serving as an index for detecting the absence of toner is read (S100). Then, when the image forming mode is selected, the timer t is cleared (S101), the count-up is started (S102), and it is determined every 100 msec whether the image forming mode is completed or is continuing (S1).
03). If the image forming mode has ended, T
The value of s is written in the storage device (S121), and the operation ends. If the image forming mode is continuing, a signal is read from the toner sensor to determine whether "toner is present" or "toner is absent" (S104). If the signal is “with toner”, the value of Ts is set to 0 (S122), the timer t is cleared (S101), and the above operation is repeated. When the "toner present" signal is continuously output, there is sufficient toner in the toner container, and the state is as shown in FIG. 8B. If the signal is "no toner", it is determined whether the motor 25 that drives the toner supply screw 24 is in the ON state (S105). If the motor 25 is off, the timer t is cleared (S101) and the above operation is repeated. If the motor 25 is in the ON state, the value of Ts is 1
00 msec is added, and this value is set as a new Ts value (S106). That is, only when the "toner out" signal is input and the motor 25 is driven, Ts
The value of is cumulatively added.

Further, this value of Ts is compared with a preset Tlimit (S107), and this Tlimi
If it is smaller than t, the timer t is cleared (S1
01), the above operation is repeated. After that, "with toner"
When the signal is detected, the value of Ts is returned to 0, but when the "no toner" signal is continuously output, the value of Ts is cumulatively added and increases. If the value of Ts reaches Tlimit when the value of Ts is compared with Tlimit,
A toner supply warning signal is output (S108), and the operation unit 3
That is displayed on the display device 9. That is, the screen displayed as shown in FIG. 4A before the toner replenishment warning signal is output is changed to that shown in FIG. 4B, and the display prompts the toner replenishment. When the toner replenishment warning signal is output, as shown in FIG. 3 or FIG. 8D, the toner remains in the toner container but is in a very small amount. As described above, from the time when the toner continuously outputs the "no toner" signal to the time when the toner replenishment warning signal is output, as shown in FIG. Has become. After the toner replenishment warning signal is output, the timer t is cleared (S101) in the same manner as above, and the above operation is repeated.

On the other hand, when the density adjustment mode is selected, it is first determined whether or not a toner replenishment warning signal is issued (S109). When the toner replenishment warning signal is output, the end processing of the density adjustment mode is directly performed (S120), and Ts is set.
The value of is stored (S121) and the operation ends. If the toner replenishment warning signal is not issued, a toner image of the reference pattern is formed on the image carrier 1, and the density of the image is detected by the density sensor (S110). This detected value is compared with the target range in the CPU 31 (S111), and if it is the target range, the density adjustment mode is terminated (S120), the value of Ts is written (S121), and the operation is terminated. If the density is outside the target range, it is determined whether the density is higher or lower than the target (S112), and if the density is higher than the target, the operation of consuming the toner contained in the developer in the developing device is performed (S112).
113). As described above, this is performed by forming a latent image for toner consumption on the image carrier 1, developing the latent image, and cleaning it without transferring it. After this operation is completed, the image density sampling (S110) is performed again, and the above operation is repeated.

When the image density is lower than the target, the driving time of the toner supply screw 24 is T (ms) according to the degree.
ec) is calculated (S114), and the toner supply screw 24 is driven during that T (msec) (S11).
5). As a result, the toner is supplied from the toner container to the developing device, and the density of the toner contained in the developer increases.
At this time, the output signal from the toner sensor is input to the CPU, and it is determined whether "toner is present" or "toner is absent" (S116). When the input signal is the "toner present" signal, the value of Ts is set to 0 (S123), the image density is sampled again (S110), and the above operation is repeated. When the input signal is the "no toner" signal,
The driving time T of the toner supply screw 24 is set to the value of Ts.
Is added to obtain a new Ts value (S117) and compared with a preset Tlimit (S118). Tlimi
When it is smaller than t, sampling of the image density is performed again (S11
0) is performed and the above operation is repeated. Ts is Tlimit
Is reached, a toner replenishment warning signal is output (S1
19) and thereafter, the end processing of the density adjustment mode is performed (S1).
Along with 20), the value of Ts is written in the storage device 32 (S121), and the operation ends.

Even if the mode is changed to the image forming mode or the density adjusting mode in this manner, the value of Ts is stored in the storage device and continuously accumulated, so that the toner replenishment warning signal is appropriately transmitted. It becomes possible to output at the time. Alternatively, since the storage device can maintain the stored value even when the power is turned off, it is not affected by the power on / off. Also, when the toner replenishment warning signal is output in the density adjustment mode, the density adjustment mode is immediately terminated, and once the toner replenishment warning signal is output, the end processing is immediately performed even if the density adjustment mode is selected. , The density adjustment operation is not performed. Therefore, after the toner replenishment warning signal is output, the toner is not consumed by the density adjustment, and the remaining amount can be effectively used for forming a recorded image.

During the above operation, the cumulative addition of the value of Ts in the image forming mode (S106) is performed by adding 100 msec which is a reading interval of the signal from the toner sensor. It is possible to use Ts = Ts + A × 100 (msec) by multiplying by the coefficient A in consideration of the use in both the mode and the density adjustment mode, and the fact that the operation mode of the toner supply screw is significantly different in both modes.

Further, instead of adding the reading interval (100 msec) of the signal from the toner sensor, as shown in FIG. 5, 1 is added every time the number of recorded sheets is newly counted.
The time value Tprint corresponding to the recording of one sheet may be cumulatively added.

The operation described above is during the toner-free output monitoring period until the toner replenishment warning signal is output, as shown in FIG. 3, but the value of Ts is accumulated even after the toner replenishment warning signal is output. When the addition is continued and the value of Ts becomes equal to or larger than the second limit value Tlimit2, that is, when the toner shown in FIG. 3 becomes empty, a signal for prohibiting the operation of the image forming mode is output. It can also be set.

[0032]

As described above, in the image forming apparatus according to the first aspect, the toner sensor detects "no toner" under the condition that the toner consuming operation or the operation corresponding thereto is being performed. Since the preset value is added cumulatively every time, the cumulative addition value corresponds to the toner consumption amount.By comparing the cumulative addition value with the reference value, It is possible to accurately recognize that the remaining amount of toner has reached a predetermined amount. Further, the cumulative addition value is stored in the storage means,
The stored value can be maintained even if the mode is switched or the power is turned on / off. Even if the power is turned on / off or the mode is changed, the amount of toner in the toner container is reduced to a predetermined value. When this is done, it is possible to accurately recognize this and issue a toner replenishment warning signal at an appropriate time.

In the image forming apparatus according to the second aspect, since the operation in the density adjustment mode is set not to be performed after the toner replenishment warning signal is output, the remaining amount of toner is effectively used for forming a recorded image. Can be used. Therefore, it is possible to maintain the state in which image formation is possible for a long time until new toner is replenished in the toner container, and it is possible to avoid the state in which image formation cannot be performed as much as possible. In the method for detecting the absence of toner in the image forming apparatus according to the third aspect, the same operation and effect as the operation of the image forming apparatus according to the first aspect can be performed.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing an image forming apparatus which is an embodiment of the invention described in claim 1 or claim 2.

FIG. 2 is a flowchart showing an operation of the image forming apparatus shown in FIG. 1 and showing a control method of the image forming apparatus according to an embodiment of the present invention.

FIG. 3 is a diagram showing an output signal from a toner sensor of the toner container used in FIG.

4 is a diagram showing a display screen of the image forming apparatus shown in FIG.

FIG. 5 is a flowchart showing a control method of the image forming apparatus according to another embodiment of the invention described in claim 3.

FIG. 6 is a schematic sectional view showing a two-component developing device and a toner container which have been conventionally used.

7 is a vertical cross-sectional view of the toner container shown in FIG.

8 is an explanatory diagram showing an output of a toner sensor provided in the toner container shown in FIG. 7 and a remaining amount of toner.

[Explanation of symbols]

 1 Image Carrier 2 Charging Device 4 Developing Device 5 Pre-Transfer Charging Device 6 Transfer Charging Device 7 Peeling Charging Device 8 Cleaning Device 9 Electrification Exposure Lamp 10 Density Sensor 11 Original Exposure Lamp 12 Mirror 13 Carriage 14 Original Size Sensor 15 Platen Glass 16 Paper Conveyance path 21 Toner container 22, 23 Toner stirring member 24 Toner supply screw 25 Motor 26 Toner sensor 27 Toner supply pipe 31 CPU 32 Storage device 33 A / D converter 34 D / A converter 35 Input interface 36 Output interface 37 Amplifier 38 Power supply for developing device 39 Operation unit 40 Original exposure device

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Claims (3)

[Claims] 1. A two-component developer containing an image carrier capable of forming a latent image on the surface due to a difference in charging potential and a toner and a carrier is used to transfer the toner to the image carrier to transfer the latent image. A developing device that visualizes an image, a toner container that contains toner to be supplied to the developing device, a toner stirring unit that is provided in the toner container, and a toner detection sensor that is provided near the bottom of the toner container. In an image forming apparatus having: an image forming mode in which a toner image is formed on the image carrier and the toner image is transferred to a transfer material; and a toner concentration of a developer contained in the developing device is adjusted. Mode selecting means for selecting a density adjustment mode for adjusting the density of the toner image, and a transition between the two modes and the image carrier and the mode for each mode. Control means for controlling the operation of the developing device, and each time the toner detection sensor detects the absence of toner under a predetermined condition in the operation of the developing device or the operation of supplying toner to the developing device, the mode at the time of detection is as described above. A calculation unit that cumulatively adds the values set individually by either of the two modes, and compares the cumulative addition value with a preset reference value, stores the cumulative addition value, and when the mode transitions and A storage unit capable of maintaining the cumulative addition value even when the power is turned on / off; and the control unit when the cumulative addition value becomes the reference value or becomes a reference value or more. An image forming apparatus, which is set to output a toner replenishment warning signal. 2. The image forming apparatus according to claim 1, wherein the control unit suspends the density adjusting operation when the mode selected when the toner replenishing warning signal is output is the density adjusting mode. An image forming apparatus, which is set so as to prohibit the shift to the density adjustment mode when the selected mode is the image forming mode. 3. A latent image is formed by transferring a toner to the image carrier by using a two-component developer containing an image carrier capable of forming a latent image on the surface due to a difference in charging potential, and a toner and a carrier. A developing device that visualizes an image, a toner container that contains toner to be supplied to the developing device, a toner stirring unit that is provided in the toner container, and a toner detection sensor that is provided near the bottom of the toner container. A toner image is formed by adjusting a toner concentration of a developer contained in the developing device and an image forming mode in which a toner image is formed on the image carrier and the toner image is transferred to a transfer material. One of the density adjustment modes for adjusting the density of the image forming apparatus is selected, and the operation of the image carrier and the developing device is controlled for each mode. Each time the toner detection sensor detects the absence of toner under a predetermined condition in the operation of the developing device or the operation of supplying toner to the developing device, the mode at the time of detection is set separately by either of the above two modes. When the cumulative addition value reaches the reference value or becomes equal to or more than the reference value, the toner replenishment warning signal is added. Is output, and when the cumulative addition value does not exceed the reference value, the cumulative addition value is stored, and when the mode is changed and the power is turned on.
A method for controlling an image forming apparatus, including a step of maintaining the cumulative addition value even when the power is turned off.