JP2021179557A - Image forming apparatus, method for controlling image forming apparatus, and program - Google Patents

Abstract

To solve the problem in which: in a conventional image forming apparatus, when a pump unit is compressed to supply toner from a storage container to a developing unit, a load torque of a motor that drives to rotate the storage container is increased, and thus the rotation speed of the storage container does not become constant and the quality of an image formed on recording paper may be reduced.SOLUTION: In the present invention, when a pump unit is compressed, the duty ratio of a PWM signal to be input to a motor is increased by a predetermined amount. This can prevent excessive supply of toner from a storage container to a developing unit and prevent a reduction in quality of an image formed on recording paper.SELECTED DRAWING: Figure 8

Description

The present invention relates to an image forming apparatus, a control method for the image forming apparatus, and a program.

The electrophotographic image forming apparatus forms a toner image by developing an electrostatic latent image formed on a photoconductor using a developer (hereinafter, referred to as “toner”) in a developing device. Since the amount of toner that can be stored in the developing device is limited, a removable storage container is arranged in the image forming apparatus main body, and toner is appropriately supplied from the storage container to the developing device.

The accommodating container for accommodating toner includes a rotating portion that is driven to rotate, a pump portion that changes the internal pressure of the accommodating portion to discharge toner from the accommodating portion that accommodates toner, and a pump portion that transfers the rotational movement of the rotating portion. It is known to have a conversion unit that converts into expansion and contraction motion. In such an accommodating container, the toner in the accommodating portion is discharged to the developing unit by expanding and contracting the pump portion according to the rotation of the accommodating container. That is, in the accommodating container, the air taken in from the discharge port loosens the toner in the accommodating portion as the pump portion expands, and then the accommodating portion becomes a negative pressure state as the pump portion compresses, and the accommodating container. The air inside pushes out the toner covering the outlet from the outlet.
In such a storage container, in order to ensure the quality of the image formed on the recording paper, it is necessary to control the amount of toner discharged from the storage container with high precision, and therefore, the rotation speed of the storage container must be controlled. It is necessary to control with high precision.

Patent Document 1 describes the next time when the storage container is rotationally driven based on the rotational speed of the storage container when the storage container is rotationally driven based on the current setting of the PWM signal (pulse width modulation signal) input to the motor. An image forming apparatus for setting a PWM signal is disclosed. Specifically, as the setting of the PWM signal, specifically, the duty ratio of the PWM signal (hereinafter referred to as “PWM_Duty”) is set. In the image forming apparatus of Patent Document 1, the accuracy of the rotational speed of the storage container is improved by performing such a simple speed feedback.

Japanese Unexamined Patent Publication No. 2015-31737

However, in the conventional configuration, since the pump portion is expanded and contracted by the rotational movement of the rotating portion of the accommodating container, when the pump portion is compressed to supply toner from the accommodating container to the developer, the motor that rotationally drives the accommodating container is used. Load torque increases. On the other hand, the motor is rotationally driven with a predetermined torque-rotation speed characteristic (TN characteristic) determined by a fixed PWM_Duty. Therefore, when the pump portion is compressed, the load torque of the motor increases, so that the rotation speed of the motor, that is, the rotation speed of the storage container does not become constant and decreases.
As a result, the amount of toner discharged from the container to the developer is not constant, the image formed on the recording paper is partially shaded, and the quality of the image formed on the recording paper is deteriorated. There was a case that it ended up.

An object of the present invention is to provide an image forming apparatus capable of suppressing deterioration of the quality of an image formed on a recording paper in order to solve the above-mentioned problems.

The present invention comprises a developing means for developing an electrostatic latent image formed on a photoconductor using a developing agent, an accommodating portion for accommodating the developing agent, and a pump portion for performing expansion and contraction operation. It has a replenishing means for replenishing the developing agent contained in the accommodating portion by the expansion / contraction operation of the pump unit, a driving means for rotationally driving the replenishing means, and a control means for controlling the driving means. In the image forming apparatus, the control means rotationally drives the drive means based on the first drive signal in the first period, and is different from the first drive signal in the second period. It is characterized in that the drive means is rotationally driven based on a drive signal.

According to the present invention, it is possible to suppress oversupply of the developer and suppress deterioration of the quality of the image formed on the recording paper.

Schematic block diagram of the image forming apparatus Control block diagram of image forming apparatus Schematic diagram of the toner bottle mounting part Schematic diagram of the main part of the toner bottle Schematic diagram of the main part of the toner bottle Schematic diagram of the main part of the toner bottle Schematic diagram of rotation detection sensor Schematic diagram of rotation detection sensor The figure which shows the TN characteristic of a drive motor Timing chart showing the signal or status of each part during toner replenishment operation Flowchart showing processing during toner replenishment operation

Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.
However, the embodiments described below are merely examples, and are not intended to limit the scope of the present invention to them. Moreover, not all combinations of features described in the following embodiments are essential for the means of solving the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
<Explanation of image forming apparatus>
FIG. 1 is a schematic cross-sectional view of the image forming apparatus 200. In the image forming apparatus 200, four image forming portions Pa, Pb, Pc, and Pd forming a toner image of each color component are arranged side by side in the conveying direction of the intermediate transfer belt 7. The image forming portion Pa forms a yellow toner image, the image forming portion Pb forms a magenta toner image, the image forming portion Pc forms a cyan toner image, and the image forming portion Pd forms a black toner image. do.

Toner bottles Ta, Tb, Tc, and Td that can be attached to and detached from the image forming apparatus 200 are attached to the image forming apparatus 200. The toner bottle Ta contains yellow toner, the toner bottle Tb contains magenta toner, the toner bottle Tc contains cyan toner, and the toner bottle Td contains black toner. There is. The toner bottles Ta, Tb, Tc, and Td correspond to storage containers for containing toner.
Since the image forming units Pa, Pb, Pc, and Pd have the same configuration, the image forming units Pa, Pb, Pc, and Pd are referred to as image forming units P in the following description. Further, the toner bottles Ta, Tb, Tc, and Td are referred to as toner bottles T.

The image forming unit P includes a photosensitive drum 1 provided with a photosensitive layer functioning as a photoconductor on the surface of a columnar metal roller, a charger 2 for charging the photosensitive drum 1, and a developer 100 containing toner. .. The arrow A direction is the direction in which the photosensitive drum 1 rotates. After the photosensitive drum 1 is charged by the charger 2, the laser exposure apparatus 3 exposes the photosensitive drum 1 based on the image data. As a result, an electrostatic latent image is formed on the photosensitive drum 1. Then, the developer 100 develops the electrostatic latent image on the photosensitive drum 1 with toner. As a result, a toner image is formed on the photosensitive drum 1. The developing device 100 includes a magnetic permeability sensor 610 (FIG. 2) that detects the amount of toner accumulated in the developing device 100. When the magnetic permeability sensor 610 detects that the amount of toner in the developer 100 has decreased, toner is supplied from the toner bottle T to the developer 100.

The intermediate transfer belt 7 is hung around a secondary transfer facing roller 8, a driven roller 17, a first tension roller 18, and a second tension roller 19. The intermediate transfer belt 7 is rotated in the direction of arrow B by the rotational drive of the secondary transfer opposed roller 8.

The image forming unit P includes a primary transfer roller 4 that transfers the toner image on the photosensitive drum 1 to the intermediate transfer belt 7. While the toner image formed on the photosensitive drum 1 passes through the primary transfer nip portion T1 in which the photosensitive drum 1 and the intermediate transfer belt 7 are pressed by the primary transfer roller 4, the primary transfer roller 4 is subjected to the primary transfer. A transfer voltage is applied. As a result, the toner image on the photosensitive drum 1 is transferred to the intermediate transfer belt 7. By superimposing and transferring the toner images formed on the photosensitive drums 1a, 1b, 1c, and 1d on the intermediate transfer belt 7, a full-color toner image is supported on the intermediate transfer belt 7. The toner remaining on the photosensitive drum 1 is removed by the drum cleaner 6.

At this time, the paper feed roller (not shown) feeds the recording material S stored in the cassette unit 60, and the transport roller pair 61 conveys the recording material S toward the registration roller pair 62. The registration roller 63 adjusts the timing of transporting the recording material S to the secondary transfer nip portion T2 so that the toner image on the intermediate transfer belt 7 is transferred to a desired position on the recording material S.

A secondary transfer roller 9 is arranged on the opposite side of the secondary transfer facing roller 8 with respect to the intermediate transfer belt 7. In the secondary transfer nip portion T2 in which the secondary transfer facing roller 8 and the intermediate transfer belt 7 are pressed against the secondary transfer roller 9 in response to the application of the secondary transfer voltage to the secondary transfer facing roller 8. , The toner image on the intermediate transfer belt 7 is transferred to the recording material S. The toner remaining on the intermediate transfer belt 7 without being transferred to the recording material S in the secondary transfer nip portion T2 is removed by the belt cleaner 11.

After the toner image is transferred to the recording material S by the secondary transfer roller 9, the recording material S is transferred to the fixing device 13. The fuser 13 includes a fixing roller having a heater and a pressure roller, and the toner image on the recording material S is fixed to the recording material S by the heat of the heater and the pressure of the fixing roller and the pressure roller. The recording material S on which the toner image is fixed by the fuser 13 is discharged from the image forming apparatus 200 by the paper ejection roller pair 64.

<Structure of control unit>
FIG. 2 is a control block diagram of the image forming apparatus 200 according to the present embodiment. The control unit 600 includes a CPU 601 and an ASIC 602, a motor drive circuit 603, an EEPROM 606, and a sensor output detection circuit 607.

The CPU 601 is a control circuit that controls each device of the image forming apparatus 200.
The ASIC 602 is a dedicated IC that controls the toner replenishment operation of supplying toner from the toner bottle T to the developer 100.
The motor drive circuit 603 controls the voltage supplied to the drive motor 604 to control the drive motor 604.
The EEPROM 606 is a non-volatile memory, and stores in advance the duty information (information on the increased duty ratio; details will be described later) of the PWM signal which is a drive signal for instructing the motor drive circuit 603.
The sensor output detection circuit outputs a signal that fluctuates according to the result of detecting the convex portion 220 (predetermined portion) of the toner bottle T by the rotation detection sensor 203.

The magnetic permeability sensor 610 outputs a signal that fluctuates according to the amount of toner in the developer 100 to the CPU 601. The CPU 601 detects the amount of toner in the developer 100 based on the output value of the magnetic permeability sensor 610. When the amount of toner in the developing device 100 drops to a predetermined amount or less, the CPU 601 controls the ASIC to perform a toner replenishing operation of replenishing the toner from the toner bottle T to the developing device 100.

The motor drive circuit 603 supplies a voltage to the drive motor 604 according to the PWM signal from the ASIC 602 while the ASIC 602 outputs the ENB signal. At this time, the toner bottle T is rotationally driven. On the other hand, in response to the ASIC 602 stopping the ENB signal, the supply of voltage from the motor drive circuit 603 to the drive motor 604 is stopped. At this time, the toner bottle T stops rotating.
The drive motor 604 is a drive source that rotates the toner bottle T in order to supply toner from the toner bottle T to the developer 100. The drive motor 604 is connected to the toner bottle T via a drive gear 300 (described later in FIG. 3), and rotates the toner bottle T by its own rotation.

In this embodiment, a DC motor (DC brush motor) is used as the drive motor 604. Therefore, the rotational speed of the drive motor 604 and the rotational drive force of the drive motor 604 change according to PWM_Duty (more accurately, the average supply voltage to the drive motor 604 determined by PWM_Duty).
The ASIC 602 sets PWM_Duty so that the toner bottle T rotates at a target rotation speed, and outputs the PWM signal to the motor drive circuit 603. The motor drive circuit 603 supplies a (average) voltage determined by PWM_Duty to the drive motor 604 to drive the drive motor 604. When the drive motor 604 rotates at the target rotation speed, the toner bottle T rotates at the target rotation speed.

The rotation detection sensor 203 is an optical sensor including a light emitting unit and a light receiving unit, and outputs a signal corresponding to the amount of light received by the light receiving unit. While the convex portion 220 (predetermined portion) of the toner bottle T passes through the detection position, the light receiving amount of the rotation detection sensor 203 drops below the threshold value, and the predetermined portion of the toner bottle T in the rotation direction in which the toner bottle T rotates. While the region other than the detection position passes through the detection position, the light receiving amount of the rotation detection sensor 203 becomes equal to or higher than the threshold value. The specific configuration of the rotation detection sensor 203 will be described later with reference to FIGS. 5 and 6.

The sensor output detection circuit 607 outputs a high-level signal based on the output signal of the rotation detection sensor 203 if the light reception amount of the rotation detection sensor 203 is equal to or more than the threshold value, and the light reception amount of the rotation detection sensor 203 is less than the threshold value. If low level signal is output. That is, the sensor output detection circuit 607 outputs a low-level signal while the predetermined portion of the toner bottle T has passed the detection position, and the region other than the predetermined portion of the toner bottle T has passed the detection position. Output a high level signal in between.

The ASIC 602 measures the time when a predetermined portion of the toner bottle T is detected by the rotation detection sensor 203. That is, the ASIC 602 measures the time during which the sensor output detection circuit 607 outputs a low-level signal. The time measured by the sensor output detection circuit 607 is stored in the RAM 609 of the ASIC 602.

<Explanation of mounting part>
The toner bottle T is mounted on the mounting portion 310 provided in the image forming apparatus 200. The configuration of the mounting portion 310 will be described with reference to FIG. FIG. 3A is a partial front view of the mounting portion 310 as viewed from the front with respect to the mounting direction of the toner bottle T, and FIG. 3B is a perspective view for explaining the inside of the mounting portion 310. As shown in FIG. 3B, the toner bottle T is mounted in the direction of the arrow M with respect to the mounting portion 310. The arrow M direction is parallel to the rotation axis direction of the photosensitive drum 1 of the image forming apparatus 200. Further, the direction of taking out the toner bottle T from the mounting portion 310 is opposite to the M direction.

The mounting unit 310 is a rotation direction regulating unit 311 that regulates the rotation of the cap portion 222 (FIG. 4) of the toner bottle T in response to the rotation of the drive gear 300 connected to the rotation shaft of the drive motor 604 and the toner bottle T. A bottom portion 321 and a rotation axis direction regulating portion 312 are provided. The rotation axis direction regulating unit 312 regulates the movement of the cap portion 222 (FIG. 4) in the rotation axis direction by locking the cap portion 222 (FIG. 4) of the toner bottle T.

When the toner bottle T is attached to the bottom portion 321, it communicates with the discharge port (discharge hole) 211 (FIG. 4) of the toner bottle T and receives the toner discharged from the toner bottle T (reception hole). It has 313. The toner discharged from the discharge port 211 (FIG. 4) of the toner bottle T is supplied to the developing device 100 through the receiving port 313. In this embodiment, the diameter of the receiving port is the same as that of the discharging port 211, for example, about 2 mm.
The drive gear 300 is fixed to the rotation shaft of the drive motor 604 (FIG. 4), and transmits the rotational drive force from the drive motor 604 to the toner bottle T mounted on the mounting portion 310.

<Explanation of toner bottle>
Next, the main part of the toner bottle T will be described with reference to FIG. FIG. 4A is an external view of the toner bottle T mounted on the mounting portion 310. 4B and 4C are schematic views showing the structure inside the cap portion 222 of the toner bottle T mounted on the mounting portion 310.

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

The cam groove 214 and the convex portion 220 formed in the drive transmission unit 206 rotate integrally with the drive transmission unit 206. The drive motor 604 transmits a rotational driving force to the drive transmission unit 206 of the toner bottle T via the drive gear 300, so that the drive transmission unit 206 of the toner bottle T and the accommodating unit 207 connected to the drive transmission unit 206 are connected. Rotates. A convex portion 220 is spirally formed inside the accommodating portion 207, and the toner in the accommodating portion 207 is conveyed toward the discharge port 211 as the accommodating portion 207 rotates.

On the other hand, since the rotation of the cap portion 222 is restricted by the mounting portion 310, the cap portion 222 does not rotate even if the drive transmission portion 206 rotates. The discharge port 211, the pump unit 210, and the reciprocating member 213 are also regulated so as not to rotate together with the cap unit 222, and even if the drive transmission unit 206 rotates, the discharge port 211, the pump unit 210, and the reciprocating member 213 rotate. do not.

A rotation restricting groove that regulates the rotation of the reciprocating member 213 by the rotation of the drive transmission portion 206 is formed inside the cap portion 222, and the reciprocating member 213 is engaged with the rotation restricting groove ( FIG. 5). Further, the reciprocating member 213 is connected to the pump portion 210, and a claw portion (not shown) engages with the cam groove 214 of the drive transmission portion 206. As a result, the reciprocating member 213 moves along the cam groove 214 in a state where the reciprocating member 213 is restricted from rotating in response to the rotation of the drive transmission unit 206, so that the reciprocating member 213 is indicated by an arrow. It reciprocates in the X direction (longitudinal direction of the toner bottle T).

The reciprocating member 213 is connected to the pump unit 210. As the reciprocating member 213 reciprocates, the pump unit 210 alternately repeats expansion and compression. The pump portion 210 extends as the reciprocating member 213 moves in the direction of arrow X. Then, as the pump unit 210 expands, the internal pressure in the toner bottle T decreases, air is sucked in from the discharge port 211, and the toner in the discharge unit 212 is released. On the other hand, the reciprocating member 213 moves in the direction opposite to the arrow X direction, so that the pump unit 210 is compressed. Then, as the pump unit 210 compresses, the internal pressure in the toner bottle T rises, and the toner accumulated in the discharge port 211 is supplied from the discharge port 211 to the developer 100 through the toner transport path (not shown).

Here, FIG. 4B is a cross-sectional view of a main part of the toner bottle T showing a state in which the pump portion 210 of the toner bottle T is fully extended, and FIG. 4C is a state in which the pump portion 210 of the toner bottle T is maximally compressed. .. The pump unit 210 is a resin bellows-shaped pump whose volume of the pump unit 210 changes according to the expansion / contraction operation of the pump unit 210. That is, in the pump portion 210, the "mountain fold" portion and the "valley fold" portion are alternately and repeatedly arranged along the longitudinal direction of the toner bottle T.

In the present embodiment, the replenishment operation is performed twice while the toner bottle T makes one rotation. One toner replenishment operation starts from the state in which the pump unit 210 is fully extended, compresses the pump unit 210, then expands the pump unit 210, and ends in the state in which the pump unit 210 is fully extended.
In the cam groove 214, two peak portions and two valley regions are formed in the order of valley → peak → valley → peak. When the position of the cam groove 214 with which the reciprocating member 213 is engaged is the peak portion, the pump portion 210 is compressed to the maximum (state shown in FIG. 4B). When the position of the cam groove 214 with which the reciprocating member 213 is engaged is in the valley region, the pump portion 210 extends to the maximum (state shown in FIG. 4C).

<Configuration of rotation detection sensor>
Next, the rotation detection sensor 203 provided in the image forming apparatus 200 will be described with reference to FIGS. 5 and 6. The rotation detection sensor 203 is an optical sensor having a light emitting unit and a light receiving unit that receives light emitted from the light emitting unit. When the toner bottle T is mounted on the mounting portion 310, the flag 204 comes into contact with the mounting portion 310 by its own weight at a position overlapping the region where the convex portion 220 is formed in the direction in which the toner bottle T is mounted. Further, the flag 204 is swingably supported around the rotation shaft 204a. When the flag 204 is pushed up to the convex portion 220 with the rotation of the toner bottle T, the flag 204 swings around the rotation shaft 204a, and the flag 204 is directed from the light emitting portion of the rotation detection sensor 203 toward the light receiving portion. Move to a light-shielding position that blocks the optical path of the emitted light.

FIG. 5 shows a position overlapping the region where the convex portion 220 is formed in the direction in which the toner bottle T is mounted, and a region (other region) different from the convex portion 220 in the rotation direction in which the drive transmission portion 206 rotates. It shows how the flag 204 is in contact. Since the flag 204 is not located at the light blocking position, the light receiving unit can receive the light emitted from the light emitting unit. In this case, the amount of light received by the light receiving unit is equal to or greater than the threshold value.

On the other hand, FIG. 6 shows how the flag 204 is in contact with the convex portion 220. Since the flag 204 is located at the light blocking position, the light receiving unit cannot receive the light emitted from the light emitting unit. In this case, the amount of light received by the light receiving unit is less than the threshold value.

The sensor output detection circuit 607 notifies the ASIC 602 of the result of comparing the output value indicating the received light amount of the rotation detection sensor 203 with the threshold value. The sensor output detection circuit 607 (FIG. 2) outputs a high-level signal (logic'H') when the received light amount of the light receiving unit is equal to or higher than the threshold value, and low-level when the received light amount of the light receiving unit is less than the threshold value. Output a signal (logic'L'). That is, the output signal of the sensor output detection circuit 607 changes from high level to low level in response to the flag 204 being pushed up by the first region of the convex portion 220. Then, this output signal is transmitted from the low level in response to the movement of the flag 204 along the second region of the convex portion 220 downstream of the first region of the convex portion 220 in the rotation direction of the toner bottle T. Change to a high level.

Therefore, as shown in FIG. 5, while the flag 204 is in contact with the region other than the convex portion 220, the sensor output detection circuit 607 (FIG. 2) outputs a high-level signal, and as shown in FIG. 6, While the flag 204 is in contact with the protrusion 220, the sensor output detection circuit 607 (FIG. 2) outputs a low level signal. That is, the sensor output detection circuit 607 and the rotation detection sensor 203 function as a detection unit for detecting the convex portion 220 of the toner bottle T rotated by the drive motor 604.

Here, in the present embodiment, the convex portion 220 pushes up the flag 204 from before the pump portion 210 starts to compress until the pump portion 210 compresses. The sensor output detection circuit 607 (FIG. 2) outputs a low-level signal (logic'L') from before the pump unit 210 begins to compress until the pump unit 210 compresses to the maximum. Then, in the sensor output detection circuit 607 (FIG. 2), the low-level signal (logic'L') is switched to the high-level signal (logic'H') in a state where the pump unit 210 is compressed to the maximum. Further, the sensor output detection circuit 607 (FIG. 2) is high from the state in which the pump unit 210 is maximally compressed to the state in which the pump unit 210 is expanded to the maximum extent. Output the level signal (logic'H').

<Rotation speed control processing>
In this embodiment, a DC motor (DC brush motor) is used as the drive motor 604. When the drive motor 604 rotates and drives the toner bottle T, the rotational speed of the toner bottle T fluctuates according to the weight of the toner bottle T. That is, by supplying the toner from the toner bottle T to the developer 100, the amount of toner contained in the toner bottle T is reduced, so that the toner bottle T becomes lighter. Therefore, when the drive motor 604 is continuously controlled without changing the PWM signal, the rotation speed of the toner bottle T increases as the amount of toner contained in the toner bottle T decreases.

Then, the amount of toner (replenishment amount) discharged from the toner bottle T to the developer 100 becomes smaller than the target amount. This is because, in the present embodiment, the toner replenishment amount [g] is related to the following formula (1), and when the rotation speed of the toner bottle T increases from the target, the toner replenishment time [sec] (pump unit 210 is compressed). This is because the time spent) is shorter than the target.

Toner supply amount [g]
= Amount of toner that can be discharged within a unit time [g / sec] x Toner replenishment time [sec]
... Equation (1)

In the present embodiment, the amount of toner [g / sec] that can be discharged within a unit time is a substantially constant value regardless of the rotation speed of the toner bottle T. This is because the discharge port 211 for discharging toner from the toner bottle T to the developer 100 is as narrow as 2 mm in diameter, which limits the amount of toner that can be discharged at one time.
Due to the relationship of the above formula (1), when the rotation speed of the toner bottle T increases, the toner replenishment time becomes short, and the amount of toner replenished discharged to the developer 100 becomes smaller than the target amount. As a result, the density of the printed matter may be reduced.

In order to reduce this, the ASIC 602 measures the time when the convex portion 220 of the toner bottle T is detected by the rotation detection sensor 203 while one toner replenishment operation is executed, and PWM is based on this measurement result. Correct the signal control value. That is, the PWM signal when the next toner bottle T is rotationally driven by the drive motor 604 based on the rotational speed of the toner bottle T when the drive motor 604 rotationally drives the toner bottle T based on the current PWM signal. To set. As a result, the PWM signal is corrected based on the actually measured rotation information of the toner bottle T, so that the fluctuation of the rotation speed of the toner bottle T according to the change in the weight of the toner bottle T can be reduced.

However, since the expansion and contraction of the pump unit 210 is performed by the rotational movement of the toner bottle T, the load torque of the drive motor 604 increases when the pump unit 210 is compressed. On the other hand, the drive motor 604 is rotationally driven by the torque-rotation speed characteristic (TN characteristic) determined by the fixed PWM_Duty set by the ASIC 602 based on the rotation speed of the previous toner bottle T. Therefore, when the pump unit 210 is compressed, the rotation speed of the drive motor 604 and the toner bottle T is lower than the target rotation speed due to the increase in the load torque of the drive motor 604 due to the compression of the pump unit 210.
As a result, the amount of toner replenished becomes larger than the target amount, and the density of the printed matter may be partially increased.

Therefore, in the image forming apparatus of the present embodiment, the set value of PWM_Duty is increased by a predetermined amount when the pump unit 210 is compressed. Thereby, the decrease in the rotation speed of the toner bottle T can be reduced. As a result, it is possible to suppress the oversupply of toner to the developer 100, improve the accuracy of the toner supply amount, and improve the quality of the image formed on the recording paper.

Next, the toner replenishing operation of replenishing the toner from the toner bottle T to the developer 100 will be described with reference to FIGS. 7, 8 and 9.
First, with reference to FIG. 7, the relationship between the duty ratio (PWM_Duty) of the PWM signal and the torque-rotation speed characteristic (TN characteristic) of the drive motor 604 will be briefly described. FIG. 7 is a diagram showing torque-rotation speed characteristics (TN characteristics) of the drive motor 604. In FIG. 7, the line 71 shows the torque-rotation speed characteristic (TN characteristic) when PWM_Duty has a certain value D1. Further, the line 72 shows the torque-rotation speed characteristic (TN characteristic) when PWM_Duty is D2 (> D1).

That is, the torque-rotation speed characteristic (TN characteristic) is expressed by the following equation (2).
T = -α ・ N + β ・ V ・ ・ ・ Equation (2)
Here, α and β are proportionality constants, N is the motor rotation speed, and V is the motor applied voltage. The motor applied voltage V is a voltage supplied to the drive motor 604 by PWM control of the 24V voltage in the image forming apparatus by the motor drive circuit 603, and its value (average value) is determined by PWM_Duty.

That is, the torque-rotation speed characteristic (TN characteristic) of the drive motor 604 translates in the A direction of the arrow 73 in FIG. 7 because the β · V term of the equation (2) increases as the PWM_Duty increases. do. On the other hand, the smaller the PWM_Duty of the PWM signal, the smaller the β · V term of the equation (2), so that the PWM signal moves in parallel in the B direction of the arrow 73 in FIG.
Therefore, assuming that the load torque of the drive motor 604 is Tr1, the rotation speed of the drive motor 604 is V1 when PWM_Duty is D1, and the rotation speed of the drive motor 604 is V2 when PWM_Duty is D2. Therefore, by increasing the set value of PWM_Duty from D1 to D2 by a predetermined amount when the pump unit 210 is compressed, it is possible to reduce the decrease in the rotation speed of the toner bottle T when the pump unit 210 is compressed.

Next, the toner replenishing operation of replenishing the toner from the toner bottle T to the developer 100 will be described with reference to FIG. FIG. 8 is a timing chart showing signals or states of each part during the toner replenishment operation.
Specifically, in FIG. 8, (a) shows the rotation detection sensor output (output signal of the sensor output detection circuit 607) during the replenishment operation. (B) shows PWM_Duty. (C) indicates the position of the cam groove 214 with which the reciprocating member 213 is engaged. (D) shows the load torque of the drive motor 604. (E) shows the rotation speed of the drive motor 604.
Note that, in FIG. 8, the lines 81b and 81e show the rotation speeds of the PWM_Duty and the drive motor 604 when the set value of the PWM_Duty is not increased at the time of compression of the pump unit 210, respectively, as in the conventional technique. There is.

First, at time t0, the CPU 601 determines that the toner replenishment operation is unnecessary. Therefore, the PWM signal and the ENB signal are not output, the drive motor 604 is stopped, and the load torque thereof is 0. At this point, the position of the cam groove 214 with which the reciprocating member 213 is engaged is in the valley region, and the pump portion 210 is in the maximum extended state (see FIG. 4C). Further, the flag 204 is in contact with a region other than the convex portion 220, and the rotation detection sensor output is in a high level state.

Then, at time t1, the CPU 601 determines that the toner replenishment operation is required, and instructs the ASIC 602 to start the toner replenishment. Then, the ASIC 602 starts outputting the PWM signal and the ENB signal to the motor drive circuit 603. Here, the duty value (PWM_Duty) of the PWM signal is a value set by the ASIC 602 based on the rotation speed of the previous toner bottle T. Here, this PWM_Duty is set to D1. The motor drive circuit 603 applies a voltage to the drive motor 604 based on the PWM signal. Then, the drive motor 604 starts accelerating, and during that time, the acceleration torque accompanying the acceleration is generated on the shaft of the drive motor 604 in addition to the friction torque for steady driving of the toner bottle T as the load torque.

At time t2, the rotational speed of the drive motor 604 reaches almost a steady speed, and the load torque of the drive motor 604 is dominated by the friction torque for driving the toner bottle T.

At time t3 when the rotation speed of the drive motor 604 is sufficiently stable, the flag 204 comes into contact with the convex portion 220, and the rotation detection sensor output signal changes from a high level to a low level. At this time, the ASIC 602 uses this as a trigger to start counting up the count value Tn indicating the time during which the sensor output detection circuit 607 outputs a low-level signal.

At time t4, the position of the cam groove 214 with which the reciprocating member 213 is engaged starts to move from the valley region toward the peak portion, and the compression of the pump portion 210 is started. Along with this, the load torque of the drive motor 604 increases. Therefore, in the prior art, at this time, the rotation speed of the drive motor 604 has been greatly reduced as shown by the line 81e in (e).

Therefore, in the present embodiment, as shown in (b), the set value of PWM_Duty is increased from D1 to D2 in the section after the time t4 after driving the drive motor 604 as D1 in the period from the time t1. Drives the drive motor 604. As a result, the rotation speed of the drive motor 604 when the load torque of the drive motor 604 reaches the peak torque Tr1 can be improved to V2, which is faster than V1, and the rotation speed of the toner bottle T when the pump unit 210 is compressed. Can be reduced.

Here, the timing for increasing the set value of PWM_Duty to D2 at time t4 is after a predetermined time T1 has elapsed after the signal of the rotation detection sensor output changes from high level to low level. The rotation speed of the toner bottle T is controlled to be substantially constant by adjusting the set value of PWM_Duty. Therefore, the predetermined time T1 becomes substantially the same value each time, and the timing of increasing the set value of PWM_Duty by a predetermined amount can be substantially matched with the timing at which the compression of the pump unit 210 is started.
The set value of PWM_Duty to be increased is stored in the EEPROM 606 in advance at the time of shipment from the factory of the image forming apparatus. This set value is set so that the amount of increase in the load torque of the drive motor 604 due to the compression of the pump unit 210 is experimentally obtained, and the decrease in the rotation speed of the toner bottle T due to this can be suppressed within an allowable range. ..

At time t5, the position of the cam groove 214 with which the reciprocating member 213 is engaged is at the peak portion, and the pump portion 210 is in the maximum compressed state (see FIG. 4B). At this point, the flag 204 separates from contact with the protrusion 220 and the output signal of the sensor output detection circuit 607 changes from low level to high level. In response to this, the ASIC 602 stops counting up the count value Tn, and stores the count value Tn at that time in the RAM 609. The CPU 601 calculates the PWM_Duty value D1 at the time of the next toner replenishment based on the count value Tn stored in the RAM 609. At time t5, the load torque of the drive motor 604, which has increased due to the compression of the pump unit 210 of the drive motor 604, is lower than the peak torque Tr1. Further, the rotation speed of the drive motor 604 is also increased from the minimum value V2.

After a predetermined time T2 elapses after the output signal of the sensor output detection circuit 607 changes from low level to high level at time t5, at time t6, the ASIC 602 stops outputting the PWM signal and ENB signal to the motor drive circuit 603. do. The pump unit 210 gradually expands from time t5 to t6, and at time t6, the position of the cam groove 214 with which the reciprocating member 213 is engaged becomes a position where the position shifts to the valley region.

The drive motor 604, which has been coasting from time t6, stops at time t7, and its load torque becomes zero. The position of the cam groove 214 with which the reciprocating member 213 is engaged stops in a state of shifting to the valley region. It should be noted that the reason why the output of the PWM signal is stopped at the time t6 after the lapse of the predetermined time T2 from the time t5 is that the reciprocating member 213 is engaged in consideration of the fact that the drive motor 604 coasts from the time t6 to the time t7. This is to stop the position of the cam groove 214 in the valley region.

Next, the toner replenishment operation in which the toner bottle T replenishes the developer 100 with toner will be described with reference to the flowchart of FIG. The toner replenishment operation shown in FIG. 9 is executed by the CPU 601 reading a program stored in the ROM. Further, it is carried out by the CPU 601 controlling the ASIC 602. The CPU 601 discharges a predetermined amount of toner from the developer 100 when the amount of toner in the developer 100 detected by the magnetic permeability sensor 610 is equal to or less than a predetermined amount, or based on image data. When it is predicted that the toner replenishment operation shown in FIG. 9 is started.

In step S101, the CPU 601 outputs a signal instructing the ASIC 602 to start replenishing the toner. Then, the ASIC 602 reads and sets the PWM_Duty setting value D1 stored in the RAM 609.

In step S102, the ASIC 602 initializes the count value Tn of the time when the sensor output detection circuit 607 is outputting the low level signal to 0.

In step S103, the ASIC 602 outputs a PWM signal and an ENB signal to the motor drive circuit 603. As a result, the drive motor 604 starts driving.

Next, in step S104, the ASIC 602 determines whether or not the output signal of the sensor output detection circuit 607 has dropped from the high level to the low level. When the falling edge of the output signal of the sensor output detection circuit 607 is not detected (No in S104), the process waits as it is. When the falling edge is detected (Yes in S104), the process proceeds to step S105.

In step S105, the ASIC 602 starts counting up the count value Tn indicating the time when the sensor output detection circuit 607 is outputting the low level signal. The count value Tn is counted and increased in a predetermined clock cycle.

Next, in step S106, the ASIC 602 determines whether or not the count value Tn is equal to or greater than the value corresponding to the predetermined time T1. When the count value Tn is less than the value corresponding to the predetermined time T1 (No in S106), the process waits as it is. When the count value Tn becomes equal to or greater than the value corresponding to T1 for a predetermined time (Yes in S106), the process proceeds to step S107.

In step S107, the ASIC 602 reads out the increased duty ratio stored in advance in the EEPROM 606. Then, the value D2 obtained by adding the increment to D1 which is the PWM_Duty set in step S101 is set as a new PWM_Duty.
As described above, in the present embodiment, the set value of PWM_Duty is increased from D1 to D2 in response to the increase in the load torque of the drive motor 604 due to the compression of the pump unit 210. As a result, it is possible to reduce a decrease in the rotation speed of the toner bottle T when the pump unit 210 is compressed.

Next, in step S108, the ASIC 602 determines whether or not the output signal of the sensor output detection circuit 607 has risen from the low level to the high level. When the rising edge of the output signal of the sensor output detection circuit 607 is not detected (No in S108), it stands by as it is. When the rising edge is detected (Yes in S108), the process proceeds to step S109.

In step S109, the ASIC 602 stops counting up the count value Tn, which indicates the time during which the sensor output detection circuit 607 outputs a low-level signal.
Then, in step S110, the CPU 601 updates the PWM_Duty setting value D1 at the time of the next toner replenishment based on the count value Tn measured by the ASIC 602, and stores it in the RAM 609.

Next, in step S111, the ASIC 602 determines whether or not T2 has elapsed for a predetermined time after the output signal of the sensor output detection circuit 607 rises from the low level to the high level. If the predetermined time T2 has not elapsed (No in S111), the process waits as it is. When the predetermined time T2 has elapsed (Yes in S111), the process proceeds to step S112.

In step S112, the ASIC 602 stops the output of the PWM signal and the ENB signal. As a result, the drive motor 604 stops driving.
Then, the CPU 601 and the ASIC 602 complete the toner replenishment operation.

As described above, according to the image forming apparatus of the present embodiment, when the load torque of the drive motor 604 increases with the compression of the pump unit 210, the speed of the toner bottle T decreases by increasing the set value of PWM_Duty by a predetermined amount. To reduce. As a result, oversupply of toner to the developer 100 can be suppressed, the accuracy of the amount of toner replenished can be improved, and the quality of the image formed on the recording paper can be improved.

In the present embodiment, when the load torque of the drive motor 604 is increased due to the compression of the pump unit 210, the set value D2 of PWM_Duty is increased by a predetermined amount fixed in time with respect to the set value D1. However, the increase in PWM_Duty is not limited to a fixed value that is constant over time. For example, the increase in Duty may be changed over time so as to cancel the speed fluctuation of the drive motor 604 according to the fluctuation of the load torque of the drive motor 604.
Specifically, the set value of PWM_Duty that cancels the fluctuation of the load torque of the drive motor 604 at the time of compression of the pump unit 210 is experimentally obtained in advance as a pattern that changes with time, and it is obtained at the time of shipment from the factory. Store in EEPROM 606. Then, when the pump unit 210 is compressed, the set value of PWM_Duty is increased by the amount of the stored pattern. As a result, the speed fluctuation of the toner bottle T can be further reduced and the accuracy of the toner replenishment amount can be further improved as compared with the case where the set value of PWM_Duty is increased by a fixed predetermined amount.

<Other embodiments>
The present invention supplies a program that realizes one or more functions of the above-described embodiment to a system or device via a network or storage medium, and one or more processors in the computer of the system or device reads and executes the program. It can also be realized by the processing to be performed. It can also be realized by a circuit (for example, ASIC) that realizes one or more functions.
Further, the present invention may be applied to a system composed of a plurality of devices or a device composed of one device.
The present invention is not limited to the above-described embodiment, and various modifications can be made based on the gist of the present invention, and these are not excluded from the scope of the present invention. That is, all the configurations in which the above-mentioned configuration example and the modification thereof are combined are included in the present invention.

100 Developer 200 Image forming device 210 Pump part 207 Storage part 603 Motor drive circuit 604 Drive motor T Toner bottle

Claims (9)

A developing means for developing an electrostatic latent image formed on a photoconductor using a developing agent,
A replenishing means that includes an accommodating portion for accommodating a developing agent and a pump portion that performs an expansion / contraction operation, and supplies the developing agent contained in the accommodating portion to the developing means by the expansion / contraction operation of the pump portion accompanying a rotational drive. ,
A driving means for rotationally driving the replenishing means and
A control means for controlling the drive means and
It is an image forming apparatus having
The control means rotationally drives the drive means based on the first drive signal in the first period, and drives the drive means based on a second drive signal different from the first drive signal in the second period. An image forming apparatus characterized in that the means is rotationally driven. The control means drives the drive means by the first drive signal for a predetermined time in the first period, and then drives the drive means by the second drive signal in the second period. The image forming apparatus according to claim 1. The first drive signal is a PWM signal having a first duty ratio, and is a PWM signal.
The image forming apparatus according to claim 2, wherein the second drive signal is a PWM signal having a second duty ratio different from that of the first duty ratio. The image forming apparatus according to claim 3, wherein the second duty ratio is larger than the first duty ratio. The image forming apparatus according to claim 4, wherein the second duty ratio is a fixed value constant within the second period. The image forming apparatus according to claim 4, wherein the second duty ratio is a value consisting of a pattern that changes with time within the second period. The invention according to any one of claims 1 to 6, wherein the control means drives the drive means by the second drive signal in the second period, and then stops the drive of the drive means. The image forming apparatus described. A developing means for developing an electrostatic latent image formed on a photoconductor using a developing agent,
A replenishing means that includes an accommodating portion for accommodating a developing agent and a pump portion that performs an expansion / contraction operation, and supplies the developing agent contained in the accommodating portion to the developing means by the expansion / contraction operation of the pump portion accompanying a rotational drive. ,
A driving means for rotationally driving the replenishing means and
It is a control method of an image forming apparatus having
In the first period, the first step of rotationally driving the drive means based on the first drive signal, and
A control method for an image forming apparatus, comprising: a second step of rotationally driving the drive means based on a second drive signal different from the first drive signal in the second period. A program for causing a computer to execute the control method of the image forming apparatus according to claim 8.

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