JP2021047222A - Image formation apparatus - Google Patents

Abstract

To provide an image formation apparatus which can suppress the influence of the erroneous detection of detection means for toner density in comparison to a case where a prediction value of toner density is not used.SOLUTION: An image formation apparatus comprises: development means which develops an electrostatic latent image formed on an image carrier by using toner stored therein and a developer containing a carrier; detection means which detects the density of the toner in the development means to output a detection value; supply means which supplies the toner to the development means; and control means which controls the supply means so as to supply the toner on the basis of the detection value, calculates the density of the toner remaining in the development means as the prediction value and controls the supply means by using the prediction value when a predetermined condition about the prediction value is satisfied.SELECTED DRAWING: Figure 3

Description

The present invention relates to an image forming apparatus.

Patent Document 1 describes a developing device that develops an electrostatic latent image formed on an image carrier using toner and a magnetic carrier, and toner replenishment that replenishes toner from a toner bottle containing toner for replenishment to the developing device. A control unit that executably controls a means, a toner concentration detecting means for detecting information about the toner concentration in the developing device, and a normal mode for determining the amount of toner replenished by the toner replenishing means based on the detection result of the toner concentration detecting means. In an image forming apparatus having a remaining amount detecting unit for detecting information on the remaining amount in the toner bottle and a replacement detecting means for detecting information for determining replacement of the toner bottle, the control unit is a remaining amount. After prohibiting the image formation operation based on the detection result of the detection unit, it is immediately determined whether to allow the image formation operation based on the detection result of the exchange detection means. An image forming apparatus is disclosed, which comprises executing a replenishment restriction mode that limits a toner replenishment amount by a toner replenishment means rather than a normal mode in a predetermined initial period.

Patent Document 2 is interchangeably provided with an image carrier capable of carrying an electrostatic image and a developing device for developing an electrostatic image of the image carrier into a toner image using a developer containing toner and a carrier. A replenishment unit that replenishes the replenishing developer stored in the developer container to the developing device, a detection means that can detect information on the toner concentration in the developing device, and whether or not the developing agent container has been replaced. Image formation is prohibited based on the detection result of the exchange detection means that detects the information for determination and the detection result of the detection means, and the prohibition of the image formation operation is released based on the detection result of the exchange detection means. In an image forming apparatus including a control unit for controlling an operation, the control unit performs an image forming operation regardless of the detection result of the detecting means until a predetermined condition is reached after the prohibition of the image forming operation is released. An image forming apparatus is disclosed, which is characterized in that the image forming operation is prohibited or not based on the detection result of the detecting means when a predetermined condition is reached.

Reference 3 describes a toner replenishing means for replenishing toner from the toner replenishing device to the developing tank of the developing device, a developing agent stirring means for stirring the developer in the developing tank to which the toner is replenished by the toner replenishing means, and a developing agent. A developer transporting means that makes the developer stirred by the stirring means go around in the developing tank, and a developer transporting that goes around the developing tank by the developing agent transporting means from the position of the developing tank where the toner is replenished by the toner replenishing means. A toner concentration detecting means for detecting the toner concentration of the developing agent being conveyed at a predetermined position downstream in the direction, and a maximum / minimum value acquiring means for acquiring the maximum and minimum values of the toner concentration of the developing agent detected by the toner concentration detecting means. And the maximum / minimum value difference acquisition means that acquires the difference between the maximum value and the minimum value acquired by the maximum / minimum value acquisition means, and the difference that compares the difference acquired by the maximum / minimum value difference acquisition means with a predetermined reference value. An image characterized by having a reference value comparing means and a printing processing progressing means for advancing the printing process when the deviation from the reference value of the difference converges within the permissible value. The forming apparatus is disclosed.

Japanese Unexamined Patent Publication No. 2018-087997 Japanese Patent No. 6184259 Japanese Unexamined Patent Publication No. 2015-118218

An object of the present invention is to provide an image forming apparatus capable of suppressing the influence of erroneous detection of the toner concentration detecting means as compared with the case where the predicted value of the toner concentration is not used.

The image forming apparatus according to the first aspect includes a developing means for developing an electrostatic latent image formed on an image carrier using a developing agent containing a contained toner and a carrier, and a toner in the developing means. A detection means that detects the concentration of and outputs a detected value, a replenishing means that replenishes the developing means with toner, and a control means that controls the replenishing means so as to replenish the toner based on the detected value. , The concentration of the toner remaining in the developing means is calculated as a predicted value, and when a predetermined condition regarding the predicted value is satisfied, the control means for further controlling the replenishing means using the predicted value. And includes.

The image forming apparatus according to the second aspect is the image forming apparatus according to the first aspect, in which the control means sets a first replenishment mode of replenishing toner based on the detected value, and the detected value and the predicted value. It is provided with a second replenishment mode in which the replenishment amount is smaller than the replenishment amount in the first replenishment mode, and when a predetermined condition regarding the predicted value is satisfied, the first replenishment mode is used. The replenishment means is controlled by switching to the second replenishment mode.

The image forming apparatus according to the third aspect is the image forming apparatus according to the second aspect, and the control means said when the deviation between the detected value and the predicted value exceeds a predetermined deviation threshold value. The replenishment means is controlled by switching to the replenishment mode of.

The image forming apparatus according to the fourth aspect is the image forming apparatus according to the third aspect, and the control means said when the deviation between the detected value and the predicted value exceeds a predetermined deviation threshold value. The replenishment means is controlled so as to switch to the replenishment mode of the above and stop the replenishment of toner.

The image forming apparatus according to the fifth aspect is the image forming apparatus according to the third aspect or the fourth aspect, and the control means said when the divergence exceeds the divergence threshold value and then becomes equal to or less than the divergence threshold value again. The replenishment means is controlled so as to return to the first replenishment mode.

The image forming apparatus according to the sixth aspect is the image forming apparatus according to the third aspect or the fourth aspect, and the control means said that the control means said from the time when the divergence exceeded the divergence threshold until a predetermined time elapsed. The replenishment means is controlled so as to execute the second replenishment mode.

In the image forming apparatus according to the third aspect or the fourth aspect, in the image forming apparatus according to the seventh aspect, a predetermined supply threshold value is set for the detected value when the toner is supplied to the developing means. The control means controls the replenishment means so as to return to the first replenishment mode when the detected value becomes less than the replenishment threshold value after the divergence exceeds the divergence threshold value.

The image forming apparatus according to an eighth aspect is the image forming apparatus according to any one of the second to seventh aspects, and the control means is the second aspect during a specific period during which the image forming apparatus is in operation. It executes the replenishment mode.

The image forming apparatus according to the ninth aspect is replaceable in the image forming apparatus according to the eighth aspect in a state where the replenishment means is filled with a certain amount of toner, and the control means is exchanged by the replenishment means. The replenishment means is controlled so as to execute the second replenishment mode from the time when the second replenishment mode is performed until the first predetermined time elapses.

The image forming apparatus according to the tenth aspect is replaceable in the image forming apparatus according to the eighth or ninth aspect in a state where the replenishment means is filled with a certain amount of toner, and the control means is said. The second replenishment mode is not executed in the period from the time when it is predicted that no toner remains in the replenishment means to the time when the second predetermined time goes back.

According to the first aspect and the second aspect, it is possible to provide an image forming apparatus capable of suppressing the influence of erroneous detection of the toner concentration detecting means as compared with the case where the predicted value of the toner concentration is not used. It has the effect of being able to do it.

According to the third aspect and the fourth aspect, the amount of toner replenished is as compared with the case where the control means switches to the second replenishment mode and controls the replenishment means without being based on the comparison between the deviation and the deviation threshold value. The effect is that the timing of the change to the reduction operation is set more accurately.

According to the fifth aspect, the time for reducing the toner replenishment amount is controlled more accurately as compared with the case where the control means controls the replenishment means to return to the first replenishment mode without being based on the deviation threshold value. It has the effect of being done.

According to the sixth aspect, as compared with the case where the control means controls the execution period of the second replenishment mode without being based on the time from the time when the divergence exceeds the divergence threshold value to the lapse of a predetermined time. As a result, the time required to reduce the amount of toner replenished is controlled more appropriately.

According to the seventh aspect, the time for reducing the toner replenishment amount is controlled more accurately as compared with the case where the control means controls the replenishment means to return to the first replenishment mode without being based on the replenishment threshold. It has the effect of being done.

According to the eighth aspect, the second replenishment mode is performed during an appropriate period during operation as compared with the case where the control means executes the second replenishment mode during an unrestricted period during which the image forming apparatus is in operation. Has the effect of being executed.

According to the ninth aspect, as compared with the case where the control means controls the replenishment means to execute the second replenishment mode without considering a predetermined time from the time when the replenishment means is replaced. It has the effect that the second replenishment mode is executed during a more effective period of operation.

According to the tenth aspect, the control means does not perform the reduction operation without considering the period from the time when it is predicted that no toner remains in the replenishment means to the time when the second predetermined time goes back. This has the effect of suppressing malfunction of the image forming apparatus when the replenishment means is replaced, as compared with the case where the replenishment means is replaced.

It is a figure which shows an example of the structure of the image forming apparatus which concerns on embodiment. It is a figure which shows an example of the structure of the developer provided in the image forming apparatus which concerns on embodiment. It is a figure explaining the toner replenishment operation in the image forming apparatus which concerns on embodiment. (A) is a graph showing the detected value and the predicted value of the ATC sensor immediately before the toner cartridge is emptied, and (b) is a diagram for explaining the application section of the combined replenishment mode and the normal replenishment mode. It is a flowchart which shows the flow of the toner replenishment processing in the image forming apparatus which concerns on embodiment. It is a figure explaining the detection principle of the toner density in a developer by an ATC sensor. In the toner replenishment operation of the image forming apparatus according to the embodiment, (a) is a diagram for explaining a normal replenishment mode, and (b) is a diagram for explaining an erroneous detection of a toner concentration immediately after replacement of a toner cartridge.

Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings.

FIG. 1 shows an example of the configuration of the image forming apparatus according to the present embodiment. As shown in FIG. 1, in the image forming apparatus 10, an intermediate transfer belt 40 made of an endless belt is supported by a plurality of rolls 42 with a predetermined tension. Further, on the intermediate transfer belt 40, an image recording unit corresponding to each color of cyan (C), magenta (M), yellow (Y), and black (K) is placed along the belt traveling direction P of the intermediate transfer belt 40. 44C, 44M, 44Y, 44K are arranged in this order. Since each image recording unit has the same configuration, the reference numerals corresponding to the respective colors will be omitted in the following description unless otherwise specified.

Each image recording unit 44 has a photoconductor drum 46 (image carrier) rotatably supported by an apparatus main frame (not shown), and the photoconductor drum 46 rotates around each photoconductor drum 46. A cleaner 48, an erase lamp (not shown), a charger 50, a laser scanning device 12, a developing device 52, and a primary transfer roll 54 are arranged in this order along a direction (clockwise in FIG. 1).

That is, after the toner remaining on the photoconductor drum 46 is removed by the cleaner 48, the electric charge on the photoconductor drum 46 is removed by the erase lamp for static elimination, further charged by the charger 50, and photosensitized by the laser scanning device 12. Light is applied to the surface of the body drum 46 to form a latent image. Then, the latent image formed by the laser scanning device 12 is developed into a toner image by the developing device 52 and transferred to the intermediate transfer belt 40 by the primary transfer roll 54. Sub-scanning (scanning in the Y-axis direction shown in FIG. 1) is performed by each photoconductor drum 46, and main scanning (scanning in the X-axis direction shown in FIG. 1) is performed by the laser scanning device 12.

On the other hand, a recording medium (hereinafter, “paper”) to be image-formed is housed in a paper feed cassette (not shown), and is fed out one by one by a pickup roll 56 provided on the paper feed side of the paper feed cassette. The unwound paper is conveyed by a predetermined number of roll pairs 58 along the path shown by the broken line in FIG. 1, is sent to the pressure contact position of the secondary transfer roll 60, and is fed by the secondary transfer roll 60 to the intermediate transfer belt 40. The above color image is collectively transferred (secondary transfer) to paper. The paper on which the color image is transferred is conveyed to the fixing device 64 by the paper conveying system 62, and after the image fixing process (heating, pressurization, etc.) is performed by the fixing device 64, the paper is discharged to a tray (not shown). It has become.

The image forming apparatus 10 further includes a control unit 70 that controls the image forming apparatus 10 in an integrated manner. The control unit 70 is composed of a CPU, a ROM, a RAM, and the like (not shown), and the CPU reads out various control programs of the image forming apparatus 10 stored in the ROM, expands them into the RAM, and executes them. The control unit 70 also executes a toner replenishment process for maintaining a constant toner concentration in the developer 52, which will be described later. However, the toner replenishment process may not only be executed by the control unit 70, but may also be executed by, for example, a control means under the control unit 70 that mainly controls the developing device 52.

Here, with reference to FIG. 2, the developing device 52 according to the present embodiment included in the image forming apparatus 10 will be described in more detail. In the image forming apparatus 10, as an example of the developing agent used in the developing device 52, a two-component developing agent containing a carrier as a component in addition to toner is used.

As shown in FIGS. 2A and 2B, the developing device 52 includes a developing roll 52A, a supply auger 52B, a stirring auger 52C, a toner supply unit 52D, and an ATC sensor 14.

The toner supply unit 52D is provided at the end of the stirring auger 52C in the main scanning direction. The end in the main scanning direction provided with the toner supply unit 52D is located on the front side of the image forming apparatus 10, and toner is supplied from the toner supply unit 52D by opening and closing a door (not shown). Toner supply to the toner supply unit 52D is performed from a toner cart (not shown) connected to the toner supply unit 52D. The toner cartridge includes a supply unit driven by a motor, and rotates the motor to replenish the toner. The amount of toner replenished is adjusted by changing the rotation speed or rotation time of the motor. In the image forming apparatus 10 according to the present embodiment, the above toner replenishment process is executed by the control unit 70.

Here, the toner cartridge is filled with a certain amount of toner, and when the toner in the toner cartridge becomes empty, it can be replaced with a new toner cartridge. The image forming apparatus 10 may include a dispenser (transport path) between the toner cartridge and the developing device 52. In this case, toner may be replenished from the dispenser.

The toner supplied from the toner supply unit 52D is conveyed in the −X direction shown in FIG. 2A while being agitated by the stirring auger 52C, and is delivered to the supply auger 52B at the end in the X-axis direction. The toner supplied from the supply auger 52B is further supplied to the developing roll 52A.
That is, the toner supplied from the toner supply unit 52D moves in the developing device 52 along the arrow indicated by the symbol “R” in FIG. 2A.

The ATC sensor 14 is a sensor that detects the concentration of toner existing inside the developing device 52, and is provided at the end portion of the developing device 52 in the −X direction. The replenishment of toner from the toner cartridge to the developer 52 is feedback-controlled based on the toner concentration detected by the ATC sensor 14. That is, if the output value of the ATC sensor 14 (hereinafter, “sensor output value”) is a sensor output value corresponding to a high toner concentration, the replenishment from the toner cartridge is reduced, and the sensor output value corresponding to a low toner concentration is sufficient. For example, the supply from the toner cartridge will be increased.

As described above, the image forming apparatus 10 uses a two-component developer containing a toner and a carrier as a developing agent, and the carrier is formed by using a magnetic material.
The ATC sensor 14 estimates the toner concentration by measuring the magnetic permeability of carriers per unit volume V in the developing device 52. The toner concentration is defined as toner concentration = toner amount / (toner amount + carrier amount) × 100 (%). In the image forming apparatus 10 according to the present embodiment, the carriers are not used in image forming but stay in the developing device 52, and the amount of carriers is kept substantially constant. However, this embodiment can be applied even to an image forming apparatus in which a carrier is replenished.

The principle of detecting the toner concentration by the ATC sensor 14 will be described with reference to FIG. FIG. 6 schematically shows the amount of toner and carriers contained in the unit volume V in the developing device 52 facing the ATC sensor 14 when the toner concentration (denoted as “TC” in FIG. 6) changes variously. Shown. In FIG. 6, it is assumed that a total of 10 toners and carriers are filled in the unit volume V under a normal state.

FIG. 6A shows a normal state of the toner concentration, and 5 toners and 5 carriers are filled in each. On the other hand, FIG. 6B shows a state in which the toner concentration is high, and 7 toners and 3 carriers are filled. Further, FIG. 6C shows a state in which the toner concentration is low, and 3 toners and 7 carriers are filled. Then, in the image forming apparatus 10, the sensor output value and the toner density are associated with each other in advance by using experiments, simulations, and the like.

The toner concentration is preferably maintained constant in the normal state shown in FIG. 6A. However, the toner concentration may not be maintained normally due to, for example, erroneous detection of the ATC sensor 14. An example of a factor that causes erroneous detection of the toner concentration in the ATC sensor 14 is a compressed state of the developer in the developing device 52. The compressed state of the developer means a state in which the total amount of the developer (toner and carrier) per unit volume V in the developing device 52 is excessively larger than the normal state. FIG. 6D schematically shows this compressed state. That is, while the normal value of the total amount of toner and carriers per unit volume V in the developing device 52 according to the present embodiment is 10, in FIG. 6D, 10 toners and 10 carriers. The total amount is 20 pieces. In the present embodiment, the "erroneous detection" means that the ATC sensor 14 detects a value that exceeds the detection variation of the toner concentration and deviates from the actual toner concentration.

Even in the state shown in FIG. 6 (d), the number of toner particles and the number of carrier particles are the same, which is the same as the normal state shown in FIG. 6 (a). However, since the absolute amount of carriers is large, the ATC sensor 14 detects a high magnetic permeability, and as a result, sends an erroneous control value that the toner concentration is low to the control unit 70. Since the control unit 70 executes the toner replenishment process based on the sensor output value, the control unit 70 that receives the sensor output value corresponding to the low toner concentration controls the toner cartridge so as to increase the toner replenishment amount. That is, if the sensor output value is an erroneous value, a state in which the toner concentration cannot be maintained normally occurs.

With reference to FIG. 7, the case where the above-mentioned toner concentration cannot be maintained normally will be described in more detail together with the normal toner replenishment operation. FIG. 7 (a) is a diagram showing a normal (normal) toner replenishment operation, <1> is a change of the sensor output with time, and <2> is an execution of the replenishment operation (in FIGS. 7 (a) and <2>. The timing of "ON") and stop (indicated as "OFF" in FIG. 7A <2>) is shown. In FIG. 7A, since the sensor output corresponds to the magnitude of the magnetic permeability, the direction in which the sensor output increases corresponds to the direction in which the toner decreases. Further, when the control unit 70 executes the toner replenishment process, the replenishment threshold TCth is set, and the control unit 70 controls the motor of the toner cartridge with the replenishment threshold TCth as a target value to control the amount of toner in the developer 52. Adjust (toner concentration).

In FIG. 7A, the initial state is a state in which the toner concentration in the developing device 52 is relatively high and the toner replenishment operation is stopped. Subsequently, the ATC sensor 14 detects that the toner is gradually consumed and the supply threshold value TCth is exceeded at time t1. Then, the control unit 70 rotates the motor for replenishing the toner cartridge and executes the toner replenishment operation until time t2. Next, when the toner replenishment operation is stopped at time t2, the toner concentration gradually decreases, and when the replenishment threshold TCth is reached again at time t3, the control unit 70 executes the toner replenishment operation again. The above is the toner replenishment operation by the control unit 70 in the normal case (normal case).

Next, with reference to FIG. 7B, an example of a case where the ATC sensor 14 causes an erroneous detection of the toner concentration will be described. FIG. 7B illustrates the state immediately after the toner cartridge is replaced as an example of false detection by the ATC sensor 14. 7 (b) <1> shows the time change of the sensor output, and FIG. 7 (b) <2> shows the execution (ON) and stop (OFF) of the toner replenishment operation.

Immediately after the toner cartridge is replaced, there is almost no toner remaining in the developer 52, so the ATC sensor 14 outputs a sensor output corresponding to a low toner concentration. The control unit 70 tries to rapidly replenish the toner by increasing the rotation speed (or rotation time) of the motor included in the toner cartridge in order to quickly return from the low toner concentration state to the normal toner concentration. In such a state, the above-mentioned compressed state of the developer is likely to occur.

In the example shown in FIG. 7B <1>, a false detection De of the ATC sensor 14 due to the compressed state occurs at time t1. That is, although the toner is replenished and the toner concentration in the developing device 52 is increased, the sensor output is maintained at a value corresponding to the low toner concentration. Once such a state occurs, a vicious cycle occurs, the stirring in the developing device 52 cannot keep up, the toner concentration becomes uncontrollable, and the image forming apparatus 10 may fail. The false detection of the ATC sensor 14 due to the compressed state of the developer is not only immediately after replacing the toner cartridge, but also rapidly replenishes the toner, for example, after continuously printing images with a very high image density. It can also occur in some cases.

Therefore, in the present embodiment, in addition to the sensor output of the ATC sensor 14, the predicted value of the sensor output is used. That is, in the image forming apparatus 10 according to the present embodiment, the control unit 70 calculates the predicted value of the toner concentration, estimates the difference (deviation value) from the actual sensor output, and the deviation value is predetermined. When the deviation threshold is exceeded, the toner replenishment operation is stopped. This provides an image forming apparatus capable of suppressing the influence of erroneous detection of the toner concentration detecting means as compared with the case where the predicted value of the toner concentration is not used.

Here, in the present embodiment, the predicted value of the toner concentration in the developer 52 is estimated by subtracting the toner consumption from the amount of toner replenished from the toner cartridge to estimate the amount of residual toner in the developer 52, and the residual toner is estimated. Calculate by converting the amount into toner concentration. The amount of toner replenished is calculated from, for example, the rotation speed (or rotation time) of the motor included in the toner cartridge. The relationship between the rotation speed (or rotation time) of the motor and the amount of toner replenished is associated in advance by experiments, simulations, and the like. On the other hand, the consumption amount is calculated from, for example, the number of printed pixels (pixels). In the following, a replenishment operation for stopping toner replenishment due to compression of the developer (a replenishment operation using both the detected value and the predicted value of the ATC sensor 14) and a normal replenishment operation (for example, using the predicted value). The mode that executes both the detection value and the operation performed based on the replenishment threshold value) is referred to as a "combined replenishment mode", and the mode that executes only the normal replenishment operation is referred to as a "normal replenishment mode".

The toner replenishment process according to the present embodiment executed by the control unit 70 will be described with reference to FIG. FIG. 3A is a diagram illustrating a combined replenishment mode according to the present embodiment. 3 (a) <1> shows the time change of the sensor output, and FIG. 3 (a) <2> shows the execution (ON) and stop (OFF) of the toner replenishment operation.

In FIG. 3A <1>, the image forming apparatus 10 operates the combined replenishment mode, starts from a state where the toner concentration is low, executes the toner replenishment operation (that is, operates in the combined replenishment mode), and the time. It is assumed that the false detection De of the ATC sensor 14 has occurred at t1. In FIG. 3A <1>, the "detection value" (solid line) is the actual value of the sensor output, and the "predicted value" (dashed line) is the predicted sensor output value, which is the detected value and the predicted value. The difference between the values is the "deviation value ΔTC". As shown in FIG. 3A <1>, the detected value and the predicted value, which were substantially the same values up to that point, deviate after the occurrence of the false detection De. A deviation threshold value ΔTCmax is set for the deviation value ΔTC, and the control unit 70 controls the toner cartridge so as to stop the toner supply when the deviation value ΔTC exceeds the deviation threshold value ΔTCmax. In the example of FIG. 3A <1>, since the deviation value ΔTC exceeded the deviation threshold value ΔTCmax at time t2, it is estimated that a compressed state is generated in the developer in the developing device 52, and the control unit 70 uses the toner. The supply of toner is stopped. When the toner supply is stopped, the toner concentration itself in the developing device 52 is in a high state, so that it is not necessary to stop the printing (image forming) operation. However, printing (image formation) may be stopped if necessary.

When the replenishment of toner from the toner cartridge is stopped, the stirring of the developer in the developing device 52 proceeds, so that it is considered that the compressed state of the developing agent is eliminated. Therefore, in the example of FIG. 3A <1>, the toner supply is restarted at time t3. The period for stopping the replenishment of toner may be a period until the compressed state of the developer is resolved to the extent that it does not cause a problem, but in the present embodiment, after the replenishment of toner is stopped, it is determined in advance. During the stop time Ts, the toner supply is stopped (Ts = t3-t2). However, the stop time of toner replenishment is not limited to this, for example, the period from when the toner replenishment is stopped until the deviation value ΔTC becomes the deviation threshold ΔTCmax or less, or until the detection value becomes less than the supply threshold TCth. It may be the period of.

Next, the application period of the combined replenishment mode will be described with reference to FIG. As described above, since the developing agent is likely to be compressed immediately after the toner cartridge is replaced, it is preferable to operate the combined replenishment mode shortly after the toner cartridge is replaced.

On the other hand, when executing the combined replenishment mode, it is necessary to consider the state immediately before the toner cartridge is emptied. FIG. 4A shows the time change of the detected value and the predicted value immediately before the toner cartridge is emptied. In FIG. 4A, it is assumed that the image forming apparatus 10 is operating in the combined replenishment mode, and the toner cartridge is empty or can be regarded as empty at time t1. At this time, since the toner cartridge is almost empty, the toner is not replenished, and the detection value of the ATC sensor 14 exceeds the replenishment threshold TCth, indicating that the toner concentration is gradually decreasing. At this time, since the image forming apparatus 10 is operating in the combined replenishment mode, the predicted value indicates that the toner concentration is gradually increasing. Therefore, when a deviation value ΔTC occurs between the detected value and the predicted value and the condition of ΔTC> ΔTCmax is satisfied, the control unit 70 controls the toner cartridge so as to stop the toner supply.

On the other hand, when the toner cartridge becomes empty, the image forming apparatus 10 performs other processing such as detecting the fact and notifying the user to that effect. Therefore, if the combined replenishment mode is operated until the toner cartridge is almost empty, an unexpected malfunction such as a shift in the timing of detecting the emptyness of the toner cartridge may occur. Therefore, the combined replenishment mode is not operated (that is, the normal replenishment mode is operated) from the time when the toner cartridge becomes empty or nearly empty to the time when the toner cartridge goes back a predetermined time (hereinafter, "empty detection period"). ) Is preferable. The time when the toner cartridge becomes empty or nearly empty is estimated by using, for example, the rotation speed (or rotation time) of the toner supply motor after the toner cartridge is replaced.

Based on the above studies, FIG. 4B illustrates the application period of the combined replenishment mode and the application period of the normal replenishment mode. That is, as shown in FIG. 4B, since the predetermined period after the toner cartridge is replaced is a period in which false detection of the ATC sensor 14 is likely to occur, the combined replenishment mode period Tc to which the combined replenishment mode is applied is applied. And. On the other hand, the period during which false detection of the ATC sensor 14 is unlikely to occur or the period during which it is not preferable to apply the combined replenishment mode is set as the normal replenishment mode period To to which the normal replenishment mode is applied. As described above, the empty detection period is also included in this normal replenishment mode period To. Here, in each of the combined replenishment mode and the normal replenishment mode, the control unit 70 constantly executes the calculation of the predicted value. In other words, the combined replenishment mode enables the application of the predicted value, and the normal replenishment mode invalidates the application of the predicted value.

Next, the toner replenishment process executed in the image forming apparatus 10 will be described with reference to FIG. FIG. 5 is a flowchart showing a processing flow of a toner replenishment processing program executed by the image forming apparatus 10. This toner replenishment processing program is stored in a storage means such as a ROM (not shown) of the image forming apparatus 10, and a CPU (not shown) is stored at a timing when the power of the image forming apparatus 10 is turned on or when it is determined that execution needs to be started. Reads this toner replenishment processing program from a storage means such as a ROM, expands it into a RAM or the like, and executes it. In the present embodiment, the toner cartridge of the image forming apparatus 10 is replaced, and the control unit 70 starts immediately after detecting the replacement.

In step S100, the combined replenishment mode is executed. That is, the application of the predicted value is enabled. That is, the control unit 70 controls the toner supply from the toner cartridge by using both the detected value and the predicted value of the ATC sensor 14. In the following description, the toner replenishment operation using both the detection value and the predicted value of the ATC sensor 14 will be described, but the toner replenishment operation using only the detection value shown in FIG. 7A is also executed at the same time.

In step S101, it is determined whether or not the deviation value ΔTC exceeds the deviation threshold value ΔTCmax.
If the determination is negative, the process proceeds to step S105, and if the determination is positive, the process proceeds to step S102.

In step S102, the toner cartridge is controlled so as to stop the toner replenishment operation. This is because the compressed state of the developer was detected in step S101.

In step S103, it is determined whether or not the stop time Ts of the toner replenishment operation has elapsed. If the determination is negative, the process returns to step S102 and the toner replenishment operation is continued to be stopped. On the other hand, if the determination is affirmative, the process proceeds to step S104.

In step S104, the toner replenishment operation is started (restarted). This is because it is presumed that the compressed state in the developing device 52 is eliminated by stirring.

In step S105, it is determined whether or not the period of the combined replenishment mode has elapsed. The period of the combined replenishment mode is, for example, the above-mentioned combined replenishment mode period Tc. If the determination is negative, the process proceeds to step S100, and the execution of the combined replenishment mode is continued. On the other hand, if the determination is affirmative, the process proceeds to step S106.

Here, the toner replenishment operation in the section from step S100 to step S105 will be described in more detail. That is, in this section, the toner replenishment operation using the detected value is basically executed. However, in the middle of the combined replenishment mode period Tc, compression may occur due to factors such as when high-density images are continuously printed, and the deviation value ΔTC may exceed the deviation threshold value ΔTCmax. In such a case, the operation is switched to the toner replenishment operation using the detected value and the predicted value, and if the combined replenishment mode period Tc is not completed at the time of execution, the process returns to step S100 and the combined replenishment mode is continued. .. That is, as described above, the control unit 70 constantly executes the calculation of the predicted value.

In step S106, the mode is switched to the normal replenishment mode for execution. That is, the application of the predicted value is invalidated.

In step S107, it is determined whether or not the period of the normal replenishment mode has elapsed. The period of the normal replenishment mode is, for example, the above-mentioned normal replenishment mode period To. If the determination is negative, the process returns to step S106 to continue the normal replenishment mode, while if the determination is positive, the process proceeds to step S108.

In step S108, it is determined whether or not there is an instruction to end the toner replenishment processing program. If the determination is negative, the process returns to step S100 to restart the combined replenishment mode, and if the determination is positive, the toner replenishment processing program is terminated. This toner replenishment processing program is terminated, for example, when the power supply of the image forming apparatus 10 is cut off.

In the above embodiment, the mode in which the toner supply is stopped when the compressed state of the developer is detected has been described as an example, but the present invention is not limited to this, and the compressed state is quickly changed by stirring in the developing device 52. The toner replenishment may be reduced from the normal replenishment amount to the extent that the toner is replenished.

10 Image forming device 12 Laser scanning device 14 ATC sensor 40 Intermediate transfer belt 42 Roll 44, 44C, 44M, 44Y, 44K Image recording unit 46 Photoreceptor drum 48 Cleaner 50 Charger 52 Developer 52A Development roll 52B Supply auger 52C Stirring auger 52D Toner supply unit 54 Primary transfer roll 56 Pickup roll 58 Roll vs. 60 Secondary transfer roll 62 Paper transfer system 64 Fixer 70 Control unit De False detection P Travel direction TCth Replenishment threshold Ts Stop time Tc Combined replenishment mode Period To Normal replenishment Mode period V Unit volume ΔTC Deviation value ΔTCmax Deviation threshold

Claims (10)

A developing means for developing an electrostatic latent image formed on an image carrier using a developer containing a contained toner and a carrier, and
A detection means that detects the density of toner in the developing means and outputs a detected value,
A replenishment means for replenishing the developing means with toner,
It is a control means that controls the replenishment means so as to replenish the toner based on the detected value, calculates the concentration of the toner remaining in the developing means as a predicted value, and determines the predicted value in advance. When the condition is satisfied, the control means for further controlling the replenishment means using the predicted value, and the control means.
An image forming apparatus including. The control means replenishes the toner with a replenishment amount smaller than that in the first replenishment mode in which the toner is replenished based on the detected value, and the replenishment amount in the first replenishment mode using the detected value and the predicted value. Equipped with 2 replenishment modes
The image forming apparatus according to claim 1, wherein when a predetermined condition relating to the predicted value is satisfied, the first replenishment mode is switched to the second replenishment mode to control the replenishment means. The image forming according to claim 2, wherein the control means switches to the second replenishment mode and controls the replenishment means when the dissociation between the detected value and the predicted value exceeds a predetermined dissociation threshold value. apparatus. The control means controls the replenishment means so as to switch to the second replenishment mode and stop the replenishment of toner when the deviation between the detected value and the predicted value exceeds a predetermined deviation threshold value. The image forming apparatus according to claim 3. The third or fourth aspect of the present invention, wherein the control means controls the replenishment means so as to return to the first replenishment mode when the dissociation exceeds the dissociation threshold value and then falls below the dissociation threshold value again. Image forming device. According to claim 3 or 4, the control means controls the replenishment means so as to execute the second replenishment mode from the time when the divergence exceeds the divergence threshold value until a predetermined time elapses. The image forming apparatus described. A predetermined replenishment threshold value is set in the detected value when replenishing toner to the developing means.
Claim 3 or claim 4 in which the control means controls the replenishment means so as to return to the first replenishment mode when the detection value becomes less than the replenishment threshold after the dissociation exceeds the dissociation threshold. The image forming apparatus according to the above. The image forming apparatus according to any one of claims 2 to 7, wherein the control means executes the second replenishment mode during a specific period during which the image forming apparatus is in operation. The replenishment means can be replaced with a certain amount of toner filled.
The image according to claim 8, wherein the control means controls the replenishment means so as to execute the second replenishment mode from the time when the replenishment means is replaced until a first predetermined time elapses. Forming device. The replenishment means can be replaced with a certain amount of toner filled.
Claim 8 or claim that the control means does not execute the second replenishment mode in a period of time that goes back a second predetermined time from the time when it is predicted that no toner remains in the replenishment means. 9. The image forming apparatus according to 9.

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