JPH09134066A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To optimally control a toner concentration with respect to environmental fluctuations by changing the quantity of toner supplied with a toner supplying means, a threshold and the toner end detecting conditions of a toner end detecting means, in accordance with the output value of a temperature detecting means. SOLUTION: A CPU 30 first reads the output values of a T sensor 26 and a humidity sensor 29 at fixed timing, in toner supplying processing, to correct a target T-sensor output value, according to the output value of the humidity sensor 29. Then, the CPU 30 compares the read output value of the T sensor 26 with the target T-sensor output value, to obtain the difference between them and decide whether the toner is supplied or not from the difference. Then, the CPU 30 corrects the supplied toner quantity, to make it smaller when humidity is low and larger when the humidity is high, in accordance with the output value of the humidity sensor 29 and allows a toner supplying part to supply the toner by the corrected quantity, when the supply of the toner is possible. The same correction is executed to toner end processing as well.

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 such as a copying machine, a facsimile and a printer.

[0002]

2. Description of the Related Art In an image forming apparatus such as a copying machine, a facsimile or a printer, a developing means for developing an electrostatic latent image on an image carrier with a two-component developer and a two-component developer in the developing means are used. Toner replenishing means for replenishing toner, toner concentration detecting means for detecting the toner concentration of the two-component developer, and whether or not toner can be replenished to the two-component developer in the developing means from the output signal of the toner concentration detecting means. There is a toner replenishment control unit that controls the toner replenishment unit according to the result of the determination, and a toner end detection unit that detects the toner end of the toner replenishment unit.

Further, Japanese Patent Laid-Open No. 64-35579 discloses an image forming apparatus having a structure in which a developing means having a density detecting means for detecting the density of a stored developer can be joined and detached. A judgment means for judging whether or not the developing means is new when the means is joined, and a stirring means for stirring the developer in the developing means when the developing means is joined; After stirring by the stirring means, when the reading means for reading the developer density in the developing means and the joining of the new developing means by the judging means are judged, the developer density read by the reading means is stored as a reference density. And an image forming apparatus including a storage unit for storing the image.

Further, in Japanese Patent Laid-Open No. 1-130771, a developing means for accommodating toner inside to develop an electrostatic latent image, a density detecting means for detecting the density of the toner in the developing means, and the developing means. Toner supply means for supplying toner into the means, comparison means for inputting the output from the density detection means and comparing with a reference value, and control of toner supply by the toner supply means according to the variation amount of toner density An image forming apparatus is described, comprising: a control unit that performs the change, a reference value changing unit that changes the value of the reference value by manual input, and a storage unit that stores the changed value.

[0005]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
In the image forming apparatus described in Japanese Patent No. 579, no consideration is given to the case where the developing unit is not set properly or the device abnormality occurs while setting the reference concentration of the developer concentration, and whether or not the developing unit is new is determined from the PCB. There is a concern that the size of the apparatus may be increased and the cost may be increased by making a determination based on the identification number.
Further, in the image forming apparatus described in JP-A-1-133071, the reference value is changed by manual input in response to environmental changes. However, the toner concentration due to the development of the electrostatic latent image near the toner end of the toner supply means. Cannot be distinguished from the decrease in toner concentration due to environmental changes. The present invention
An object of the present invention is to provide an image forming apparatus capable of optimally controlling toner density with respect to environmental changes.

[0006]

In order to achieve the above object, the invention according to claim 1 provides an electrostatic latent image on an image bearing member with two electrostatic latent images.
Developing means for developing with a component developer, and 2 in this developing means
Toner replenishing means for replenishing the component developer with toner, toner concentration detecting means for detecting the toner concentration of the two-component developer, and an output signal of the toner concentration detecting means to the two-component developer in the developing means. In an image forming apparatus having a toner replenishment control unit for controlling the toner replenishment unit according to the result of judging whether or not toner replenishment is possible with a threshold value, and a toner end detection unit for detecting the toner end of the toner replenishment unit, A humidity detecting means for detecting the humidity and a means for changing the toner replenishing amount of the toner replenishing means, the threshold value, and the toner end detecting condition of the toner end detecting means according to the output value of the humidity detecting means. It is a thing.

According to a second aspect of the invention, there is provided a developing means for developing the electrostatic latent image on the image carrier with a two-component developer, and a toner replenishing means for replenishing the two-component developer in the developing means with toner. , A toner concentration detecting means for detecting the toner concentration of the two-component developer, and whether or not toner can be supplied to the two-component developer in the developing means based on an output signal of the toner concentration detecting means by a threshold value. In the image forming apparatus having the toner replenishment control means for controlling the toner replenishment means based on the result and the toner end detection means for detecting the toner end of the toner replenishment means, the humidity detection means for detecting the humidity and the humidity detection means When the output value of the means is not within the predetermined range, the toner replenishment amount of the toner replenishing means, the threshold value, and the toner end detection condition of the toner end detection means are predetermined. Those having a means for the high humidity state of being.

According to a third aspect of the invention, there is provided a developing means for developing the electrostatic latent image on the image bearing member with a two-component developer, and a toner replenishing means for replenishing the two-component developer in the developing means with toner. , A toner concentration detecting means for detecting the toner concentration of the two-component developer, and whether or not toner can be supplied to the two-component developer in the developing means based on an output signal of the toner concentration detecting means by a threshold value. As a result, in an image forming apparatus having a toner replenishment control means for controlling the toner replenishment means, a toner end detection means for detecting the toner end of the toner replenishment means, and a non-volatile storage means for holding data, If there is a difference of a predetermined value or more between the humidity detecting means for detecting and the output value of the humidity detecting means when the power is turned on, it is possible to detect the difference during the warm-up. Those having means for causing the toner replenished to the toner replenishing means.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 2 shows an embodiment of the invention described in claims 1 to 3. This embodiment has a main body of an image forming apparatus and a process cartridge 11 which can be attached to and detached from the main body. In this embodiment, at the time of image formation, the photoconductor 12 as an image carrier is rotated by a drive motor to be uniformly charged by the charging means 13. For example, a drum-shaped photosensitive member is used as the photosensitive member 12, a charging roller is used as the charging unit 13, and a charging bias is applied from a power source (not shown). An electrostatic latent image is formed on the photoconductor 12 by the image exposure by the exposing means after the uniform charging, and the electrostatic latent image is developed with a two-component developer by the developing unit 14a of the developing device 14 to form a toner image. The developing device 14 includes a developing unit 14a as a developing unit and a toner replenishing unit 14 as a toner replenishing unit.
b.

Further, a transfer sheet as a transfer material is fed from the sheet feeding device 15 to the registration roller 16 as shown by a broken line in the figure, and the registration roller 16 sends out the transfer sheet according to the toner image on the photoconductor 12. A transfer bias is applied from a power source to the transfer roller 17 as a transfer unit, and the toner image on the photoconductor 12 is transferred onto the transfer sheet sent from the registration roller 16, and the toner image on the transfer sheet is heated by the transfer unit. It is fixed by the fixing device 18. Also, the photoconductor 12
After the transfer of the toner image, the toner is cleaned by a cleaning device having a cleaning blade 19 and a cleaning brush 20, and is discharged by an optical charge eliminator 21 to be reused.

The developing section 14a is provided in the developing container 22.
The component developer is agitated by the agitating members 23 and 24, and the developing roller 25 adsorbs the agitated two-component developer by an internal magnet to form a magnetic brush. The magnetic brush on the developing roller 25 is conveyed to the developing area as the developing roller 25 rotates and develops the electrostatic latent image on the photoconductor 12. Here, the toner carrier constituting the two-component developer is frictionally charged by stirring or the like. Further, a toner concentration detection sensor (hereinafter referred to as T sensor) 26 as a toner concentration detection means
The output value changes depending on the density of the two-component developer in the developing container 22 (the output value changes due to the change in the magnetic permeability due to the change in the amount and density of the two-component developer). Toner concentration is detected.

In the toner replenishing section 14b, the agitator 28 and the like are driven by a toner replenishing motor to replenish the toner in the toner replenishing bottle 27 to the two-component developer in the developing container 22. The process cartridge 11 is a unit in which the photoconductor 12, the charging roller 13, the developing device 14, and the cleaning device are detachably integrated, and is detachably attached to the main body. A humidity sensor 29 as a humidity detecting means for detecting humidity is arranged near the toner supply bottle 27 in order to detect the humidity inside the image forming apparatus.

The frictional charge amount of the two-component developer and toner in the developing container 22 varies depending on the humidity, and the density of the developer changes depending on the humidity regardless of the toner concentration of the two-component developer. That is, the output value of the T sensor 26 is high at high humidity and low at low humidity even if the toner concentration is the same. In FIG. 3, the control voltage for the T sensor 26 is 6V and 8V.
The relationship between the toner density and the output value of the T sensor 26 when changed to V or 9V is shown.

As the humidity sensor 29, an element that outputs 0 to 1.0 V with respect to absolute humidity of 0 to 100% is used. The output of the humidity sensor 29 is voltage-amplified about 4 times by an operational amplifier and is output to a CPU (micro controller). The operational amplifier is driven by a power supply voltage of 5V in order to be received by the ADC (analog / digital converter) of the computer. FIG. 4 shows the relationship between the absolute humidity and the output voltage of the humidity sensor 29 (the output voltage of the operational amplifier).

When the above-described image forming operation is repeatedly performed, the toner amount of the two-component developer in the developing container 22 decreases and the toner concentration decreases, which is detected by the T sensor 26 and is determined in advance. Toner supply amount is 1
The two-component developer in the developing container 22 is replenished from 4b.

FIG. 1 shows a control system of this embodiment. In the main body, the CPU 30 as the control means, the ROM 31,
The RAM 32 and the NVRAM 33 are connected to control the entire embodiment. The NVRAM 33 is used for various adjustment values, setting values, (registration, priority mode selection) of the present embodiment.
The data of the control voltage and the number of times of image formation after the process cartridge 11 is exchanged are held.

The T sensor 26 has a predetermined voltage (control voltage) in addition to being connected to the power supply and the ground due to its structure.
Must be applied, and a control voltage is applied from a DAC (digital / analog converter) built in the CPU 30. When the CPU 30 changes the control voltage, the relationship between the toner density and the output value of the T sensor 26 changes as shown in FIG. Further, the T sensors 26 have large individual variations, and in order to accurately detect the toner density, the control voltage must be kept constant at a different value for each T sensor 26.

Output value of T sensor 26 and humidity sensor 29
Since both output voltages are analog values, they are read by the ADC built in the CPU 30. The CPU 30 is required for various control operations of the image forming system around the photoconductor 12, the sheet feeding system including the sheet feeding device 15, the driving system such as the driving motor, and the fixing system including the thermal fixing device 18 in the present embodiment. Input signals and output signals of the
Input / output is performed through the O34, the filter, the driver, and the like, and the entire control of the present embodiment is controlled such as the control of the image forming system, the paper feeding system, the drive system, and the fixing system.

As can be seen from FIG. 5, the output value of the T sensor 26 greatly changes depending on the humidity. Therefore, the CPU 30
To control the toner concentration, it is necessary to replenish the toner so that the output value (toner concentration) of the target T sensor 26 changes according to the humidity as shown by the characteristic curve A shown in FIG. That is, the CPU 30 has a target toner concentration of 6% when the humidity is low.
It is necessary to replenish the toner so that the target toner concentration is around 5% at room temperature and the target toner concentration is around 4% at high humidity.

Further, the difference in the output value of the T sensor 26 and the toner density difference at the time of high humidity are different from the toner density difference. If the same toner density change is read by the T sensor 26, the low humidity is more than the high humidity. The amount of change in the output value of the T sensor 26 increases. Therefore, when the output value of the T sensor 26 is changed and the toner is replenished, if the toner replenishment amount is the same, the toner replenishment amount becomes excessive at low humidity, and the toner replenishment amount becomes insufficient at high humidity. It is highly likely. That is, by changing the target output value (toner concentration) of the T sensor 26 with the humidity and the toner replenishment amount itself with the humidity, it is possible to realize the toner concentration control with a small concentration ripple.

In the process of controlling toner replenishment (toner replenishment process), the CPU 30 first executes T at a predetermined timing.
The output value of the sensor 26 and the output value of the humidity sensor 29 are read, and the target T sensor output value is corrected according to the output value of the humidity sensor 29. Next, the CPU 30 compares the read output value of the T-sensor 26 with the target T-sensor output value to find the difference, and determines whether or not toner replenishment is possible based on this difference.
Then, the CPU 30 controls the toner supply amount by the humidity sensor 29.
According to the output value of 1), it is corrected at low humidity and at high humidity, and when toner replenishment is enabled, the toner replenishment unit 14b is made to replenish toner by the corrected toner replenishment amount.

Further, the CPU 30 has a toner replenishing section 14b.
In the processing (toner end processing) for the toner end (state where there is no toner or a state close to it), first, the output value of the T sensor 26 and the output value of the humidity sensor 29 are read at a predetermined timing, and the output of the humidity sensor 29 is output. The target toner end T sensor output value is corrected according to the value. Next, the CPU 30 compares the read output value of the T sensor 26 with the target toner end T sensor output value to obtain the difference, and determines from the difference whether the toner replenishing unit 14b is the toner end. .

Incidentally, the CPU 30 may correct the toner end level itself with the output value of the humidity sensor 29 in the correction of the intended toner end T sensor output value, and the toner density will be maintained even if toner is continuously replenished. When the toner is thin, it may be determined that the toner supply unit 14b is the toner end. In this case, the CPU 30 may correct the number of times toner is continuously replenished by the output value of the humidity sensor 29, or may correct the toner replenishment amount itself by the output value of the humidity sensor 29.

The output voltage of the humidity sensor 29 is amplified by an operational amplifier driven by 5V and input to the ADC built in the CPU 30, and the output voltage of the operational amplifier does not normally exceed about 4.3V, but the input of the ADC built in the CPU 30. Terminal has resistance 3
Pulled up by 6. Therefore, in the toner replenishment process and the toner end process described above, when the output value of the humidity sensor 29 indicates an abnormality, for example, when the contact line or disconnection of the signal line of the humidity sensor 29 occurs, C
5V is applied to the ADC built in the PU 30. As a result, the CPU 30 detects an abnormality in the output value of the humidity sensor 29 by detecting that the voltage applied to the ADC is not within the predetermined range (for example, 4.0 V or higher).

When the CPU 30 detects an abnormality in the output value of the humidity sensor 29 and the image forming operation is prohibited, the down time becomes large. Therefore, when the abnormality of the output value of the humidity sensor 29 is detected, the target toner concentration is set to a high humidity. Target toner density at time: around 4%, for example, the output value of the humidity sensor 29 is set to 4.0 V, and the toner density control is continued. As a result, the image density is slightly reduced, but in all environments, the occurrence of scumming and toner scattering due to the high toner density is eliminated. This is because the humidity sensor 29 arranged in the apparatus has many openings in order to detect the humidity, so that dust such as toner is not generated as much as possible.

In addition, when the humidity in the device suddenly changes while the power of the device is off due to the influence of the air conditioner or the like in the use environment, the humidity changes from low humidity to high humidity and from high humidity to low humidity. Changes are possible. When the humidity changes from low humidity to high humidity, the toner concentration of the developer in the developing unit 14a becomes higher than the target toner concentration, but the toner is consumed and the toner concentration of the developer is increased by performing the image forming operation. It approaches the target toner density.

When the humidity is changed from high humidity to low humidity, the toner density of the developer in the developing section 14a is lower than the target toner density, and the image density cannot be guaranteed even if the image forming operation is performed. Will occur. So, CP
U30 performs the toner replenishment process in the same sequence as the toner replenishment process when the power of the apparatus is turned on, and causes the toner replenishment unit 14b to perform a considerable amount of toner when it is determined that the toner replenishment is necessary.

In the toner replenishing process, the CPU 30
Specifically, as shown in FIG. 6, the output value of the T sensor 26 is read by the ADC at a predetermined timing, for example, the timing when the tip of the electrostatic latent image on the photoconductor 12 passes through the developing area, and A / D conversion is performed. Then, the value Vt is stored in the NVRAM 33. Next, the CPU 30 reads the output voltage of the humidity sensor 29 by the ADC via the operational amplifier and A / D
After conversion, the value Vh is stored in the NVRAM 33.

Next, the CPU 30 determines whether or not Vh is 4.0 V or higher, thereby determining whether or not an abnormality such as poor contact or disconnection of the signal line of the humidity sensor 29 has occurred, If Vh is 4.0 V or higher, Vh is 4.0 at high humidity.
V. Next, the CPU 30 refers to the data tables as shown in FIGS. 9 and 10, and the correction value + ΔVt at which the target T sensor output value Vt ′ changes according to Vh as shown by the characteristic curve A shown in FIG. , −ΔVt is obtained, and the target T sensor output value Vt ′ is corrected by the correction values + ΔVt and −ΔVt by the calculation Vt ′ = Vt + (+ ΔVt) − (− ΔVt).

In FIGS. 9 and 10, the AMP output is the output value of the operational amplifier and the AD conversion value is AM.
It is a value obtained by A / D converting the P output by the ADC incorporated in the CPU 30. Further, Vt, Vh, and Vt 'are overwritten in the NVRAM 33 at every predetermined timing. Next, CPU3
When 0, it is determined whether or not toner supply is possible by determining whether or not Vt ′ ≧ 2.5V + A. Here, A is a value that is slightly different from the output voltage of 2.5 V of the T sensor 26 when the toner concentration is the target toner concentration, and is 0.2 V in this example.

When Vt ′ ≧ 2.5V + A and the toner can be replenished, the CPU 30 sets B = 0.7 if Vh ≦ 2.0V and 3.2V ≧ Vh> 2.0V. If there is B = 1.0, and if 3.2V <Vh, B = 1.
Let it be 2. Here, B is the toner replenishing unit 1 when replenishing the toner.
4b is a table value for correcting the drive time T with humidity. The CPU 30 uses the toner replenishing unit 14b when replenishing toner.
The driving time T is calculated by the calculation 400 ms × B, and the toner replenishment unit 14b is made to replenish the toner by T.

Further, in the toner end process, the CPU 30 specifically performs T at a predetermined timing as shown in FIG. 7, for example, at a timing when the tip of the electrostatic latent image on the photoconductor 12 passes through the developing area. The output value of the sensor 26 is ADC
Read by A / D conversion, and the value Vt is NVRA
Store in M33. Next, the CPU 30 uses the humidity sensor 2
The output voltage of 9 is read by the ADC through the operational amplifier and A / D converted, and the value Vh is stored in the NVRAM 33. The same data as that read in the toner supply process may be used as Vt and Vh.

Next, the CPU 30 determines whether or not Vh is 4.0 V or higher, thereby determining whether or not an abnormality such as poor contact or disconnection of the signal line of the humidity sensor 29 has occurred. If Vh is 4.0 V or higher, Vh is 4.0 at high humidity.
V. Next, the CPU 30 refers to the data tables as shown in FIGS. 9 and 10, and the correction value + ΔVt at which the target T sensor output value Vt ′ changes according to Vh as shown by the characteristic curve A shown in FIG. , −ΔVt is obtained, and the target T sensor output value Vt ′ is corrected by the correction values + ΔVt and −ΔVt by the calculation Vt ′ = Vt + (+ ΔVt) − (− ΔVt).

Next, the CPU 30 sets A = 0.8 if Vh ≦ 2.0V, sets B = 1.0 if 3.2V ≧ Vh> 2.0V, and sets 3.2V <Vh. If B = 1.3
And Then, the CPU 30 causes Vt ′ ≧ 2.5V + A
Toner replenishment section 14b
Is a toner end, for example, it is determined whether or not there is a toner-less state (toner near end), and Vt ′ ≧ 2.5.
If it is V + A, the toner near end is determined and the toner near end flag is set to 1. In this case, the CPU 30
Is Vt ′ ≧ 2. While continuously forming a plurality of images.
It may be possible to determine whether or not the toner replenishing unit 14b is in the toner near end state by determining whether or not the state of 5V + A is still maintained.

The temperature of the heat fixing device 18 is detected by the fixing temperature detecting means. As shown in FIG. 8, the CPU 30 determines whether the temperature of the heat fixing device 18 is 100 ° C. or less based on the output signal of the fixing temperature detecting means. Determine whether or not. Here, it is determined whether or not the temperature of the thermal fixing device 18 is 100 ° C. or lower when the temperature of the thermal fixing device 18 is higher than 100 ° C., and only a short time has passed since the power was turned off. 3 does not require the correction processing shown in FIG. 3, there is no change in humidity and environment, and the time required for the correction processing shown in FIG. 3 may be longer than the reload time. This is to prevent the correction process shown in FIG. 3 from being executed during warm-up when the temperature of the device 18 is 100 ° C. or lower.

The CPU 30 determines that the temperature of the heat fixing device 18 is 1
If the temperature is not lower than 00 ° C., the main motor and the clutch are turned on to start the rotation of the stirring members 23 and 24 of the developing unit 14a, and the T sensor 26 is processed by the same process as the flow 1 shown in FIG.
And the output voltage of the humidity sensor 29 are read, the values Vt and Vh are stored in the NVRAM 33, and Vt ′ is obtained.

Next, the CPU 30 reads the previously obtained Vt 'from the NVRAM 33, and determines whether or not the difference between the presently obtained Vt' and the previously obtained Vt 'is 0.2 V or more. Determine whether to replenish. And C
When the difference between the Vt ′ obtained this time and the Vt ′ obtained last time is 0.2 V or more and the toner can be replenished, the PU 30 sets the toner replenishment time T to 300 ms, and the toner replenishment unit 14b receives T Only replenish toner.

In this case, the toner replenishment time T is set to 300 ms, which is shorter than the toner replenishment time (400 ms) during the normal image forming operation. This is because the toner replenishment interval becomes shorter than the toner replenishment time during the normal image forming operation, so that the toner replenished from the toner replenishing unit 14b to the developing unit 14a is not sufficiently stirred by the stirring members 23 and 24. This is because the process of Flow 3 shown in FIG. 8 is executed many times during the rising period.

That is, in the process of flow 3 shown in FIG. 8, the toner replenishment time is shortened so that side effects such as toner agitation unevenness and excessive replenishment do not occur. This Figure 8
The process of the flow 3 shown in (1) is executed many times if the temperature of the thermal fixing device 18 is 100 ° C. or lower after the power supply of the present device is turned on.

The CPU 30 compares the Vt and Vh read before stirring the replenishment toner with the previously read Vt and Vh stored in the NVRAM 33, and if the difference is equal to or more than a predetermined level, the same as above. It may be configured such that various toner replenishments are performed. Characteristic curves B and C in FIG. 11 represent the correction value ΔVt and the target toner density TC in the data table, respectively.

As described above, the present embodiment is an embodiment of the invention described in claim 1, and is a development for developing the electrostatic latent image on the photoconductor 12 as an image carrier with a two-component developer. A developing section 14a as a means, a toner replenishing section 14b as a toner replenishing means for replenishing the two-component developer in the developing means 14a, and a toner concentration detecting means for detecting the toner concentration of the two-component developer. T sensor 26 of
Based on the output signal of the toner concentration detecting means 26, whether or not the toner can be replenished to the two-component developer in the developing means 14a is judged by the threshold value 2.5V + A, and the toner replenishing means 14b is controlled based on the result. A CPU 30 as a control means and a CPU 30 as a toner end detection means for detecting the toner end of the toner supply means 14b.
In an image forming apparatus having the following, a humidity sensor 29 as a humidity detecting means for detecting humidity, and a toner replenishment amount of the toner replenishing means 14b, the threshold value, and the toner according to an output value of the humidity detecting means 29. End detection means 3
C as means for changing the toner end detection condition B of 0
Since the PU 30 is provided, it is possible to make the relationship between the output value of the toner concentration detecting means and the toner concentration due to the humidity change linear, and prevent the background stain and the image density shortage. Moreover, by correcting the toner replenishment charge with humidity, the ripple of the toner concentration before and after the toner replenishment can be reduced, and the optimum toner concentration control can be performed against environmental changes.

Further, the present embodiment is an embodiment of the invention described in claim 2, and the photoconductor 12 as an image carrier is provided.
A developing section 14a as a developing means for developing the above electrostatic latent image with a two-component developer; a toner replenishing section 14b as a toner replenishing means for replenishing the two-component developer in the developing means 14a with toner; The T sensor 26 as a toner concentration detecting means for detecting the toner concentration of the two-component developer, and the developing means 14 from the output signal of the toner concentration detecting means 26.
The CPU 30 as a toner replenishment control means for controlling the toner replenishment means 14b and the toner end of the toner replenishment means 14b are judged by a threshold value to judge whether or not the toner replenishment to the two-component developer in a is judged by a threshold value. In the image forming apparatus having the CPU 30 as the toner end detecting means for detecting, if the humidity sensor 29 as the humidity detecting means for detecting the humidity and the output value of the humidity detecting means 29 are not within the predetermined range, the toner is detected. Toner replenishment amount of the replenishing means 14b, the threshold value, the toner end detecting means 3
Since the CPU 30 is provided as a means for setting the toner end detection condition of 0 to the predetermined high humidity state, the toner density control is performed at a relatively low density, so that the toner scatters due to the excessive toner density under any environment. This makes it possible to protect the humidity detecting means, which is susceptible to dust, the inside of the device, and the life extension.

Further, the present embodiment is an embodiment of the invention described in claim 3, and the photoconductor 12 as an image carrier.
A developing section 14a as a developing means for developing the above electrostatic latent image with a two-component developer; a toner replenishing section 14b as a toner replenishing means for replenishing the two-component developer in the developing means 14a with toner; The T sensor 26 as a toner concentration detecting means for detecting the toner concentration of the two-component developer, and the developing means 14 from the output signal of the toner concentration detecting means 26.
The CPU 30 as a toner replenishment control means for controlling the toner replenishment means 14b and the toner end of the toner replenishment means 14b are judged by a threshold value to judge whether or not the toner replenishment to the two-component developer in a is judged by a threshold value. In an image forming apparatus having a CPU 30 as a toner end detecting unit for detecting and an NVRAM 33 as a non-volatile storage unit for holding data, a humidity sensor 29 as a humidity detecting unit for detecting humidity, and the humidity detecting unit when the power is turned on. When the output value of the means 29 is different from the value held in the non-volatile storage means 33 by a predetermined value or more, the CPU 30 is provided as means for causing the toner replenishing means 14b to replenish toner during warm-up. Therefore, the toner density of the developer, which is affected by the image density, and the triboelectric charge amount are stable regardless of the paper feeding time of the device. Rukoto can.

[0044]

As described above, according to the first aspect of the invention, the developing means for developing the electrostatic latent image on the image bearing member with the two-component developer and the two-component developer in the developing means are provided. Toner replenishing means for replenishing toner, toner concentration detecting means for detecting the toner concentration of the two-component developer, and whether or not toner can be replenished to the two-component developer in the developing means from the output signal of the toner concentration detecting means. Is detected by a threshold value, and the humidity is detected in an image forming apparatus having a toner replenishment control unit that controls the toner replenishment unit based on the result and a toner end detection unit that detects the toner end of the toner replenishment unit. Humidity detection means, and means for changing the toner replenishment amount of the toner replenishment means, the threshold value, and the toner end detection condition of the toner end detection means in accordance with the output value of the humidity detection means. Because with a, the relationship between the output value and the toner density of the toner concentration detecting means by humidity change can be linearly, it is possible to prevent scumming, the insufficient image density. Moreover, by correcting the toner replenishment charge with humidity, the ripple of the toner concentration before and after the toner replenishment can be reduced, and the optimum toner concentration control can be performed against environmental changes.

According to the second aspect of the invention, the developing means for developing the electrostatic latent image on the image carrier with the two-component developer, and the toner replenishment for replenishing the two-component developer in the developing means with toner. Means, a toner concentration detecting means for detecting the toner concentration of the two-component developer, and whether or not toner can be supplied to the two-component developer in the developing means based on an output signal of the toner concentration detecting means by a threshold value. In the image forming apparatus having the toner replenishment control means for controlling the toner replenishment means based on the result and the toner end detection means for detecting the toner end of the toner replenishment means, the humidity detection means for detecting the humidity, If the output value of the humidity detecting means is not within the predetermined range, the toner replenishing amount of the toner replenishing means, the threshold value, and the toner end detecting condition of the toner end detecting means are determined in advance. Since it is equipped with a means for maintaining a predetermined high humidity state, by controlling the toner concentration at a relatively low concentration, it is possible to prevent the toner from scattering due to excessive toner concentration in all environments, and to prevent dust from scattering. It is possible to measure the humidity detection means that is easily affected, the protection inside the device, and the life extension.

According to the third aspect of the invention, the developing means for developing the electrostatic latent image on the image bearing member with the two-component developer, and the toner replenishing for replenishing the two-component developer in the developing means with toner. Means, a toner concentration detecting means for detecting the toner concentration of the two-component developer, and whether or not toner can be supplied to the two-component developer in the developing means based on an output signal of the toner concentration detecting means by a threshold value. And an image forming apparatus having a toner replenishment control means for controlling the toner replenishment means according to the result, a toner end detection means for detecting a toner end of the toner replenishment means, and a non-volatile storage means for holding data, If there is a difference of a predetermined value or more between the humidity detection means for detecting humidity and the output value of the humidity detection means when the power is turned on, warm up. The so comprising means for causing the toner replenished to the toner replenishing means, the toner density of the developer to influence the image density can be stabilized regardless of the sheet feeding time of the frictional charge amount of the device.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a control system according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing the same embodiment example.

FIG. 3 is a characteristic diagram showing a relationship between a toner density and a T sensor output value in the embodiment.

FIG. 4 is a characteristic diagram showing a relationship between an absolute humidity and a humidity sensor output value in the embodiment.

FIG. 5 is a diagram showing the toner density, T sensor output value, and
It is a characteristic view which shows the relationship of humidity.

FIG. 6 is a flowchart showing a part of the processing flow of the CPU in the embodiment.

FIG. 7 is a flowchart showing another part of the processing flow of the CPU in the embodiment.

FIG. 8 is a flowchart showing another part of the processing flow of the CPU in the embodiment.

FIG. 9 is a diagram showing a part of a data table of the embodiment.

FIG. 10 is a diagram showing another part of the data table according to the embodiment.

FIG. 11 is a characteristic diagram showing a correction value ΔVt and a target toner density TC in the embodiment.

[Explanation of Codes] 12 Photoreceptor 14a Developing Section 14b Toner Replenishing Section 26 T Sensor 29 Humidity Sensor 30 CPU 33 NVRAM

Claims (3)

[Claims] 1. A developing means for developing an electrostatic latent image on an image bearing member with a two-component developer, a toner replenishing means for replenishing the two-component developer in the developing means with toner, and the two-component developer. Toner concentration detecting means for detecting the toner concentration of the toner, and whether or not the toner can be replenished to the two-component developer in the developing means based on the output signal of the toner concentration detecting means, and the toner replenishment is made based on the result. In the image forming apparatus having a toner replenishment control unit for controlling the toner replenishment unit and a toner end detection unit for detecting the toner end of the toner replenishment unit, the humidity detection unit for detecting the humidity and the output value of the humidity detection unit The toner replenishment amount of the toner replenishing means,
An image forming apparatus comprising: the threshold value; and a unit that changes a toner end detection condition of the toner end detection unit. 2. A developing means for developing an electrostatic latent image on an image carrier with a two-component developer, a toner replenishing means for replenishing toner to the two-component developer in the developing means, and the two-component developer. Toner concentration detecting means for detecting the toner concentration of the toner, and whether or not the toner can be replenished to the two-component developer in the developing means based on the output signal of the toner concentration detecting means, and the toner replenishment is made based on the result. In the image forming apparatus having the toner replenishment control means for controlling the means and the toner end detection means for detecting the toner end of the toner replenishment means, the humidity detection means for detecting the humidity and the output value of the humidity detection means are predetermined. If it is not within the range, the toner replenishing amount of the toner replenishing means, the threshold value, and the toner end detecting condition of the toner end detecting means are set to a predetermined high humidity state. An image forming apparatus comprising the stage. 3. A developing means for developing an electrostatic latent image on an image carrier with a two-component developer, a toner replenishing means for replenishing the two-component developer in the developing means with toner, and the two-component developer. Toner concentration detecting means for detecting the toner concentration of the toner, and whether or not the toner can be replenished to the two-component developer in the developing means based on the output signal of the toner concentration detecting means, and the toner replenishment is made based on the result. In an image forming apparatus having a toner replenishment control unit that controls the toner replenishment unit, a toner end detection unit that detects the toner end of the toner replenishment unit, and a non-volatile storage unit that holds data, a humidity detection unit that detects the humidity. If the output value of the humidity detecting means has a difference of a predetermined value or more from the value held in the non-volatile storage means when the power is turned on, the toner replenishing means has a toner value during warm-up. An image forming apparatus comprising the means for causing the supply.