JP2001201929A - Developing device and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high performance developing device and an image forming device wherein the toner particles quantity of the two component developer in a developer vessel is maintained to a prescribed level and the optimum quantity of toner particles is accurately replenished. SOLUTION: This developing device replenishes the optimum quantity of toner highly accurately by applying a modified correction factor which is obtained in such way that the correction factor based on the toner flowing degree is multiplied by the reference pulse number Nref decided on the basis of the reference table Tref. In such a manner, even in the case where the toner replenishing quantity per speific toner replenishing screw rotations is different by color kind, the replenishment can by performed by the optimum condition based on the respective flow degree of toner particles, and quantity ratio of the two component of the two component developer in the vessel of the developing machine 8 is maintained to be constant as the result of highly accurate replenishment of optimum quantity.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing device using a two-component developer, and is applied to, for example, an image forming apparatus such as an electrophotographic or electrostatic storage type printer or copier.

[0002]

2. Description of the Related Art FIG. 9 shows an example of a conventional image forming apparatus.
1 shows a configuration of a general laser beam printer.

A laser printer forms an electrostatic latent image by image light formed based on an image signal sent from the outside as shown in FIG. 9, and develops the electrostatic latent image to superimpose a visible image. The color visible image is formed by transferring the image, the color visible image is transferred to the transfer materials 2 and 4 as sheets, and the color visible image on the transfer materials 2 and 4 is fixed.

The image forming unit includes photosensitive drums (5Y, 5M, 5C,
5K), an injection charger (7Y, 7
M, 7C, 7K) and developing devices (8Y, 8
M, 8C, 8K), and a toner replenishing tank (11Y, 11M, 1) as a toner cartridge as toner particle replenishing means.
1C, 11K), an intermediate transfer body 12, a paper feeding unit, a transfer unit, and a fixing unit 13.

The photosensitive drums 5Y, 5M, 5C, and 5K are formed by applying an organic photoconductive layer to the outer periphery of an aluminum cylinder.
The driving force of a driving motor (not shown) is transmitted to rotate. The drive motors are photosensitive drums 5Y, 5M, 5C,
5K is rotated counterclockwise in accordance with the image forming operation.

Exposure light to the photosensitive drums 5Y, 5M, 5C, and 5K is sent from the scanner units 10Y, 10M, 10C, and 10K, and selectively exposes the surfaces of the photosensitive drums 5Y, 5M, 5C, and 5K. It is configured so that an electrostatic latent image is formed.

As primary charging means, four (4) photosensitive drums 5Y, 5M, 5C and 5K for yellow (Y), magenta (M), cyan (C) and black (K) are charged for each station. Injection chargers 7Y, 7M, 7C, 7K
And each of the injection chargers 7Y, 7M, 7C,
7K has sleeves 7YS, 7MS, 7CS,
7KS is provided.

As developing means, in order to visualize the electrostatic latent image with toner, four stations for developing yellow (Y), magenta (M), cyan (C), and black (K) for each station. Developing units 8Y, 8M, 8C, 8
K, and each developing unit 8Y, 8M, 8C, 8
K has sleeves 8YS, 8MS, 8CS, 8
KS is provided. Further, each of the developing devices 8Y and 8Y
M, 8C, and 8K are detachably attached.

The intermediate transfer member 12 includes photosensitive drums 5Y and 5Y.
M, 5C, and 5K, and rotates clockwise during color image formation to form photosensitive drums 5Y, 5M, 5C, and 5K.
It rotates with the rotation of K and receives the transfer of the visible image.

The intermediate transfer body 12 contacts a transfer roller 9a, which will be described later, during image formation and conveys the transfer materials 2, 4 so that a color visible image is formed on the intermediate transfer body 12 on the transfer materials 2, 4. Simultaneous transfer is performed.

The transfer roller 9a is brought into contact with the intermediate transfer body 12 while the color visible image is being superimposedly transferred onto the intermediate transfer body 12, but is separated to the position 9b at the end of the transfer processing.

The fixing unit 13 fixes the color visible image transferred to the transfer materials 2 and 4 while transporting the transfer materials 2 and 4. The fixing unit 13 includes a fixing roller 14 for heating the transfer materials 2 and 4 and a transfer material 2 and 4 as shown in FIG.
And a pressure roller 15 for pressing the fixing roller 14 against the fixing roller 14.

The fixing roller 14 and the pressure roller 15 are formed in a hollow shape, and have heaters 16 and 17 therein, respectively. That is, the transfer materials 2 and 4 holding the color visible image are conveyed by the fixing roller 14 and the pressure roller 15, and the toner is fixed on the surface by applying heat and pressure.

After the visible image is fixed, the transfer materials 2 and 4 are discharged to a discharge unit (not shown) by a discharge roller (not shown), and the image forming operation is completed.

The cleaning means 18 includes a photosensitive drum 5
Y, 5M, 5C, 5K and the toner remaining on the intermediate transfer body 12 are cleaned. The cleaning unit 18 is a waste toner after transferring a visible image formed by the toner formed on the photosensitive drums 5Y, 5M, 5C, and 5K to the intermediate transfer body 12, or a four-color visible image formed on the intermediate transfer body 12. The waste toner after transferring the images to the transfer materials 2 and 4 is stored in a cleaner container.

Incidentally, in an image forming apparatus such as a laser beam printer or a copying machine, a two-component developer composed of toner particles (hereinafter referred to as toner) and carrier particles is often used. As is well known, the toner concentration of this two-component developer (ie, the ratio of the weight of non-magnetic toner particles to the total weight of magnetic carrier particles and non-magnetic toner particles) is a critical factor in stabilizing image quality. It has become.

Therefore, since the toner of the two-component developer is consumed during development and the toner density decreases, the magnetic resistance of the two-component developer is converted into a voltage value (ie, the toner density is converted into a voltage value). The toner concentration of the two-component developer is accurately detected at appropriate times using a concentration detection device as a toner particle amount detection unit represented by a sensor, etc., and toner is replenished in accordance with the change in the concentration. It is necessary to keep the control constant and maintain the image quality.

For example, in the configuration of the toner supply tanks (11Y, 11M, 11C, 11K) and the developing units (8Y, 8M, 8C, 8K) of the laser beam printer shown in FIG. As shown in FIG. Here, only the representative numbers are assigned to the reference numerals.

The toner replenishing tank 11 has a toner replenishing screw 27 as a toner particle conveying means for supplying toner to the developing device 8, and a pulse motor 22 (hereinafter, referred to as a “pulse motor”) via a coupling 24 and a reduction gear train 23. (Referred to as a toner supply motor 22).

The toner supply motor 22 is connected to the CPU 20 via a motor driver 21. Where the CPU
When 20 sends a one-pulse phase signal to motor driver 21, toner supply motor 22 rotates by one step angle.

The developing device 8 is arranged to face the photosensitive drum 5, and has a container filled with a two-component developer 28 (comprising magnetic carrier particles and non-magnetic toner). Further, a magnetic sensor 25 is arranged so as to be in contact with the two-component developer 28.

The magnetic sensor 25 is a sensor for converting the magnetic resistance of the two-component developer 28 into a voltage value Vatry. When the development is started, the density of the two-component developer 28 is adjusted so as to output a predetermined reference value Vref. Must be controlled.

The toner contained in the two-component developer 28 is
When the electrostatic latent image is developed and supplied to the photosensitive drum 5 in a developing area opposed to the photosensitive drum 5 by the developing sleeve 8S, the toner concentration of the two-component developer 28 decreases, and the output voltage value of the magnetic sensor 25 decreases. Vatry is also lower than the reference value Vref.

Next, with reference to FIG. 11, a description will be given of the developer concentration control for replenishing the developing unit 8 with the toner consumed by the development. However, in the following, for the sake of simplicity, only control of the yellow developing station will be referred to.

After the development is completed (1100), the magnetic sensor 25 provided in the developing device 8 supplies a voltage value Vatry corresponding to the toner density in the developing device 8 to the A / D conversion port of the CPU 20. The CPU 20 converts the voltage value Vatry into a digital value Datary (1101).

After that, the reference voltage Vre
f is compared with an A / D converted value Dref, and the difference Dd
(= Dref-Datry) is calculated (1102).

Then, a table T common to all color (Y, M, C, K) toners defined in advance from the calculated difference Dd
, The pulse number N of the phase signal supplied to the toner supply motor 22 is determined (1103).

The CPU 20 supplies the determined N-pulse phase signal to the motor driver 21 (1104).

Thus, for the N-pulse phase signal,
The toner supply motor 22 and the toner supply screw 27
It is driven to rotate by the number of steps and stopped. That is, the toner consumed by the development at this time was supplied into the container of the developing device 8 (1105).

[0030]

In the conventional developer fertility control described above, the difference Dd between Datay representing the output of the magnetic sensor and the reference value Dref is uniquely determined by the toner supply motor 22.
Since the toner is replenished in a predictable manner in terms of the rotational drive amount, if the output voltage value Vatry of the magnetic sensor 25 is the same, the rotational drive amount of the toner supply motor 22 is always the same.

However, if the amount of toner supplied per fixed rotation of the toner supply screw 27 changes,
As described above, simply converting the output of the magnetic sensor into the toner replenishment amount has a problem that the replenishment error increases.

When the replenishment error is large, the toner density greatly deviates from the allowable range of the initial set value, and when the toner density is high, toner scattering or fogging occurs.
When the toner density is low, there is a drawback that an image cannot be obtained because the image is bumped, and in the worst case, a runaway of the developer density control is caused.

As an example, the toner has a color type (Y,
(M, C, K) (even in the same color) and its flowability are generally known to differ depending on the manufacturing process.

As shown in FIG. 12, when the fluidity of the toner changes as shown in FIG. 12, even if the toner replenishment screw 27 rotates by a fixed amount, the fluidity is a numerical value of the fluidity of the toner. When the flow rate is high (when the fluidity is good), a relatively large amount of toner is replenished from the toner replenishing tank 11 to the developing device 8, and when the fluidity is low (when the fluidity is poor), the replenishing amount is small.

The present invention has been made in order to solve the above-mentioned problems of the prior art. It is an object of the present invention to always supply a proper amount of toner particles with high precision and to provide a two-component developer in a developing container. An object of the present invention is to provide a high-performance developing device and an image forming device that keep the amount of toner particles therein constant.

[0036]

In order to achieve the above object, a developing apparatus according to the present invention uses an image carrier by using a two-component developer held in a developing container comprising toner particles and carrier particles. Developing means for visualizing the latent image formed thereon with toner particles, toner particle replenishing means for replenishing toner particles to a developing container of the developing means, and toner in a two-component developer in a developing container of the developing means A toner particle amount detecting means for detecting the amount of particles, wherein the replenishing amount of toner particles based on the detection result of the toner particle amount detecting means is replenished from the toner particle replenishing means to the developing means. A control means for changing the amount is provided.

It is preferable that the control means changes the replenishment amount in accordance with the fluidity of the toner particles.

The toner particle replenishing means includes a toner particle conveying means for conveying the toner particles, a driving motor for driving the toner particle conveying means, and a rotational driving amount of the driving motor for detecting a detection result of the toner particle amount detecting means. And a correction coefficient for the rotational drive amount of the drive motor according to the flow rate of the toner particles. Preferably, the drive motor is rotated by a rotation drive amount multiplied by a correction coefficient based on the degree, and toner particles are replenished by the toner particle conveying means.

It is preferable that the toner particle replenishing means is replaceably provided, and that the control means changes the replenishing amount when the toner particle replenishing means is replaced.

Preferably, the control means changes the replenishing amount when the detection result of the toner particle amount detecting means is out of a predetermined range.

The toner particle replenishing means includes a toner particle conveying means for conveying the toner particles, and a drive motor for driving the toner particle conveying means. A table for calculating the amount of toner particles supplied to the developing unit by the toner particle conveying unit and converting the detection result of the toner particle amount detecting unit into the rotational drive amount of the drive motor is created. It is preferable that the drive motor is rotated by the rotation drive amount and the toner particles are supplied by the toner particle conveying means.

An image forming apparatus according to the present invention includes the above-described developing device, wherein the developing device visualizes a latent image with toner particles, and forms the visualized image on a sheet.

Therefore, the toner particles can be replenished under the optimum conditions, and a proper amount of the toner particles is always replenished with high accuracy, and the amount of the toner particles in the two-component developer in the developing container is kept constant. Can be.

[0044]

Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. However, the dimensions of the components described in this embodiment,
The materials, shapes, relative arrangements, and the like are not intended to limit the scope of the present invention only to them unless otherwise specified.

(First Embodiment) A first embodiment will be described with reference to FIGS.

The first embodiment is directed to a color image forming apparatus in which the composition of toner particles (hereinafter, referred to as toner) differs for each color type (Y, M, C, K), whereby the toner supply screw is fixed. When the amount of toner replenished per rotation amount differs for each color type, in order to replenish the appropriate amount of toner with high accuracy, the toner supply screw is corrected by correcting the rotation drive amount for each color type. It is to do.

The overall configuration of a laser printer as a color image forming apparatus according to the present embodiment is the same as that of the prior art, so that the outline thereof will be described with reference to FIG.

The laser printer forms an electrostatic latent image by image light formed based on an image signal sent from the outside as shown in FIG. 9, and develops the electrostatic latent image to superimpose a visible image. The color visible image is formed by transferring the image, the color visible image is transferred to the transfer materials 2 and 4 as sheets, and the color visible image on the transfer materials 2 and 4 is fixed.

The image forming section includes photosensitive drums (5Y, 5M, 5C,
5K), an injection charger (7Y, 7
M, 7C, 7K) and developing devices (8Y, 8
M, 8C, 8K), and a toner replenishing tank (11Y, 11M, 1) as a toner cartridge as toner particle replenishing means.
1C, 11K), an intermediate transfer body 12, a paper feeding unit, a transfer unit, and a fixing unit 13.

The photosensitive drums 5Y, 5M, 5C and 5K are formed by applying an organic photoconductive layer on the outer periphery of an aluminum cylinder.
The driving force of a driving motor (not shown) is transmitted to rotate. The drive motors are photosensitive drums 5Y, 5M, 5C,
5K is rotated counterclockwise in accordance with the image forming operation.

Exposure light to the photosensitive drums 5Y, 5M, 5C, and 5K is sent from the scanner units 10Y, 10M, 10C, and 10K, and selectively exposes the surfaces of the photosensitive drums 5Y, 5M, 5C, and 5K. It is configured so that an electrostatic latent image is formed.

As primary charging means, four stations for charging the photosensitive drums 5Y, 5M, 5C and 5K of yellow (Y), magenta (M), cyan (C) and black (K) are provided for each station. Injection chargers 7Y, 7M, 7C, 7K
And each of the injection chargers 7Y, 7M, 7C,
7K has sleeves 7YS, 7MS, 7CS,
7KS is provided.

In order to visualize the electrostatic latent image with toner, four developing units for developing yellow (Y), magenta (M), cyan (C), and black (K) are provided for each station. Developing units 8Y, 8M, 8C, 8
K, and each developing unit 8Y, 8M, 8C, 8
K has sleeves 8YS, 8MS, 8CS, 8
KS is provided. Further, each of the developing devices 8Y and 8Y
M, 8C, and 8K are detachably attached.

The intermediate transfer member 12 includes photosensitive drums 5Y and 5Y.
M, 5C, and 5K, and rotates clockwise during color image formation to form photosensitive drums 5Y, 5M, 5C, and 5K.
It rotates with the rotation of K and receives the transfer of the visible image.

The intermediate transfer body 12 is brought into contact with a transfer roller 9a, which will be described later, during image formation, and conveys the transfer materials 2 and 4 to form a color visible image on the intermediate transfer body 12 on the transfer materials 2 and 4. Simultaneous transfer is performed.

The transfer roller 9a is brought into contact with the intermediate transfer body 12 while the color visible image is superimposedly transferred onto the intermediate transfer body 12, but separates to the position 9b at the end of the transfer processing.

The fixing section 13 fixes the color visible image transferred to the transfer materials 2 and 4 while transporting the transfer materials 2 and 4. The fixing unit 13 includes a fixing roller 14 for heating the transfer materials 2 and 4 and a transfer material 2 and 4 as shown in FIG.
And a pressure roller 15 for pressing the fixing roller 14 against the fixing roller 14.

The fixing roller 14 and the pressure roller 15 are formed in a hollow shape, and have heaters 16 and 17 therein, respectively. That is, the transfer materials 2 and 4 holding the color visible image are conveyed by the fixing roller 14 and the pressure roller 15, and the toner is fixed on the surface by applying heat and pressure.

The transfer materials 2 and 4 after the fixing of the visible image are thereafter discharged to a discharge unit (not shown) by a discharge roller (not shown), and the image forming operation is completed.

The cleaning means 18 includes the photosensitive drum 5
Y, 5M, 5C, 5K and the toner remaining on the intermediate transfer body 12 are cleaned. The cleaning unit 18 is a waste toner after transferring a visible image formed by the toner formed on the photosensitive drums 5Y, 5M, 5C, and 5K to the intermediate transfer body 12, or a four-color visible image formed on the intermediate transfer body 12. The waste toner after transferring the images to the transfer materials 2 and 4 is stored in a cleaner container.

Next, referring to FIG. 1, the toner supply tank (1
1Y, 11M, 11C, and 11K) and its peripheral portion, only the yellow developing station will be described in detail. Here, only the representative numbers are assigned to the reference numerals.

The toner replenishing tank 11 has a toner replenishing screw 27 as a toner particle conveying means for discharging toner particles to the developing device 8, and is connected to the toner replenishing motor 22 via a coupling 24 and a reduction gear train 23. Be combined.

The toner supply motor 22 is connected to the CPU 20 via the motor driver 21. Where the CPU
When 20 sends a one-pulse phase signal to the motor driver 21, the toner supply motor rotates by one step angle.

The developing device 8 is arranged to face the photosensitive drum 5 and fills the inside of the container with a two-component developer 28. Further, a magnetic sensor 25 is arranged so as to be in contact with the two-component developer 28.

The magnetic sensor 25 is a sensor for converting the magnetic resistance of the two-component developer 28 into a voltage value Vatry. When the development is started, the density of the two-component developer 28 is adjusted so as to output a predetermined reference value Vref. Must be controlled.

The toner contained in the two-component developer 28 is
When the electrostatic latent image is developed and supplied to the photosensitive drum 5 in a developing area opposed to the photosensitive drum 5 by the developing sleeve 8S, the toner concentration of the two-component developer 28 decreases, and the output voltage value of the magnetic sensor 25 decreases. Vatry is also lower than the reference value Vref.

Next, the developer concentration control which is a feature of the present embodiment will be described with reference to FIG.

It is generally known that the toner used for forming a color image has a different fluidity depending on the color type (Y, M, C, K) of the toner. For this reason, the amount of toner supplied per fixed rotation amount of the toner supply screw also differs for each color type, as described in the related art.

As shown in FIG. 2, when the fluidity of the toner increases, the toner discharged when the toner supply motor 22 is driven to rotate by one step (hereinafter, abbreviated as "per motor step"). Weight is known to increase linearly.

Here, assuming that the inclination of the straight line is Δ, the reference fluidity of the toner is Fref, and the weight of toner discharged per motor step is Mref, the fluidity Fx
Of toner Mx discharged per motor step
Is represented by the following (Equation 1).

[0071]

Mx = Δ (Fx−Fref) + Mref

In equation (1), Δ is a value determined by the shapes of the toner supply screw and the toner supply tank.
Since ref and Mref are values that can be determined by experiments, if the value of the fluidity Fx of the toner is known, the weight Mx of the toner discharged per motor step
Can be calculated.

That is, the fluidity Fy of the yellow toner, the fluidity Fm of the magenta toner, the fluidity Fc of the cyan toner,
And the fluidity Fk of the black toner is a known value,
Weight M of each color toner discharged per motor step
y, Mm, Mc, and Mk can also be calculated from (Equation 1).

In this embodiment, Fy,
The values of Fm, Fc, and Fk are obtained from experiments, and the values of My, Mm, M
c, Mk are calculated, and predetermined addresses Ay, Am, Ac, Ak of the nonvolatile memory 29 provided in the image forming apparatus are calculated.
Mref / My, Mref / Mm, Mref / Mc,
The values γy, γm, which are obtained by converting Mref / Mk into digital values,
γc and γk are stored as correction coefficients.

Hereinafter, the developer concentration control will be described with reference to FIG. However, in the following, for the sake of simplicity, only control of the yellow developing station will be referred to.

After the development is completed (300), the magnetic sensor 25 provided in the developing device 8 supplies a voltage value Vatry corresponding to the toner density in the developing device 8 to the A / D conversion port of the CPU 20. The CPU 20 converts the voltage value Vatry into a digital value Datary (301).

After that, the reference voltage Vre
f is compared with an A / D converted value Dref, and the difference Dd
y (= Dref-Datry) is calculated (302).

The reference pulse number Nrefy of the phase signal supplied to the toner supply motor 22 is referred to from the calculated difference Dd with reference to a predetermined reference table Tref.
Is determined (303).

Here, the reference table Tref indicates that the weight of toner discharged per motor step is Mre.
f (ie, when the fluidity of the toner is Fref), a Dd-Nref created so that accurate toner replenishment can be performed.
It is a conversion table. For this reason, when the flow rate Fy of the yellow toner is different from Fref, it is not possible to perform the optimum toner supply if the toner supply screw 27 is rotationally driven by Nrefy steps.

Therefore, the CPU 20 operates in the nonvolatile memory 29.
, The yellow correction coefficient γy is read from the address Ay (304), and the correction coefficient γy is multiplied by Nrefy (Ny
= Nrefy × γy), and Nrefy is corrected to Ny (305).

Thus, the CPU 20 supplies the Ny pulse phase signal to the motor driver (306). As a result, the toner supply motor 22 and the toner supply screw 27 become N
It is driven to rotate by y steps and stopped. That is, the appropriate amount of toner consumed by the development at this time is supplied into the developing device 8 (307).

As described above, in the other color developing stations, the reference pulse number Nref determined with reference to the reference table Tref is corrected by multiplying by the correction coefficient based on the flow rate of each toner. Replenish the proper amount of toner with high accuracy.

Thus, even when the amount of toner to be supplied per fixed rotation amount of the toner supply screw is different for each color type, the toner can be supplied under optimum conditions based on the fluidity of each toner. The two-component developer 2 in the container of the developing device 8 is supplied with an appropriate amount of toner particles with high precision.
8 can be kept constant.

(Second Embodiment) A second embodiment is directed to an image forming apparatus having a detachable toner supply tank (hereinafter, referred to as a toner cartridge). However, even if the old and new cartridges are different, if the toner cartridge may have been replaced in order to replenish the appropriate amount of toner with high accuracy, the output voltage value of the magnetic sensor is used as the rotation amount of the toner supply motor. The control is performed to newly create a table for converting to a toner supply, and the amount of rotation of the toner supply screw is determined with reference to this table to perform toner supply.

The outline of the overall configuration of a laser printer as an image forming apparatus according to the present embodiment, and the configuration around the toner supply tank (for the yellow developing station) are the same as those in the first embodiment (FIG. 1). , FIG. 9), and the same reference numerals are given and the description is omitted.

First, control for setting a table for converting the output voltage value of the magnetic sensor 25 into the rotation amount of the toner supply motor 22 will be described with reference to FIGS. However,
For simplicity, only the control of the yellow development station will be referred to below.

When the power of the laser printer of FIG. 1 is turned on or the door (not shown) for attaching and detaching the toner cartridge is opened and closed, an interrupt signal Tim is supplied to the CPU 20 from a signal generator (not shown) ( 500).

When the CPU 20 receives the interrupt signal Tim, the CPU 20 determines that the toner cartridge may have been replaced, and determines the number of pulses Nf specified in the motor driver 21 in advance.
Is supplied, the toner supply screw 27 is rotated by a specified amount, and toner is supplied into the container of the developing device 8 (501).

As a result, the toner density in the developing device 8 increases, and the value obtained by A / D conversion of the output voltage Vatry of the magnetic sensor 25 becomes Datary (502).

Next, as shown in FIG.
subtracting a reference value Dref defined in advance from “try”, Δ
Dy is calculated (503), and Dy = ΔDy / Nf is calculated (504).

Here, when a one-pulse phase signal is transmitted from the CPU 20 (when the toner supply screw 27 is driven to rotate by one step and the toner is supplied to the developing device 8), the developing device 8 Is increased by Dy.

Accordingly, the toner density in the developing device 8 is reduced by the normal printing, and the value obtained by A / D converting the output voltage of the magnetic sensor 25 is changed from the reference value Dref to Da.
If the number of the toner supply screws 27 decreases, the number of steps Ny of the toner supply screw 27 driven to supply the toner to be supplied is reduced.
Can be expressed as (Equation 2).

[0093]

Ny = (Dref-Datry) / Dy = Ddy / Dy

That is, the value Ny converted by (Equation 2)
If the toner supply screw 27 is driven to rotate by the number of steps, the toner consumed by the development is supplied into the developing device 8.

The CPU 20 creates a Ddy-Ny conversion table Ty represented by (Equation 2) and overwrites and stores it in the nonvolatile memory 29 (505).

Next, in step (501), the toner supplied to the developing device 8 is discharged from the developing device 8 and the toner density is returned to the reference value (the value obtained by A / D conversion of the output voltage value of the magnetic sensor 25 becomes The control to make the reference value Dref) will be described below.

First, the CPU 20 causes a laser diode (not shown) to emit light and forms a predetermined electrostatic latent image pattern on the photosensitive drum 5 (506). This electrostatic latent image is visualized with toner in the developing device 8 (50).
7) The image is transferred onto the intermediate transfer body 12 by the transfer roller 9a, and thereafter, is scraped off by the cleaning unit 18. By the above operation, the toner in the developing device 8 is consumed, and the toner density is reduced.

Next, the CPU 20 performs A / D conversion of the output voltage Vatry of the magnetic sensor 25, overwrites the value as Datary (508), and uses the datary as the reference value Dref.
Then, it is determined whether or not the relationship of Datery <Dref is satisfied (509).

At this time, if Datary> Dref, the image for toner discharge is developed again, and
<The above operations (506 to 509) until Dref is satisfied
Continue.

If Datary <Dref, Da
The difference Ddy is calculated by subtracting try from the reference value Dref (510). That is, the difference Ddy is the toner density reduced by the development.

Therefore, the CPU 20 executes the Dd created above.
With reference to the y-Ny conversion table Ty, the pulse number Ny of the phase signal to be supplied to the motor driver 21 is determined (51).
1) The Ny pulse phase signal is supplied to the motor driver 21 (512).

Thus, the toner supply motor 22 and the toner supply screw 27 are driven to rotate by Ny steps and stopped. That is, the toner consumed by the development at this time is supplied into the developing device 8, and the value obtained by A / D converting the output voltage value of the magnetic sensor 25 becomes the reference value Dref (51).
3).

By performing the initial control as described above,
Even when the toner cartridge is replaced, it is possible to perform control for setting an optimum replenishment table for each toner filled in the cartridge.

Therefore, for example, even when the toner flow rate differs depending on the cartridge manufacturing lot due to a difference in the toner manufacturing process and the amount of toner discharged per unit rotation of the toner replenishing screw, a replenishment error occurs. It is possible to perform accurate toner supply.

Next, with reference to FIG. 6, a description will be given of a control for replenishing the toner in the developing device 8 after printing using the Ddy-Ny conversion table Ty created above.

After the development is completed (600), the CPU 20 changes the output voltage Vatry of the magnetic sensor 25 to a digital value Datr.
A / D conversion is performed to y (601), and the difference Ddy is calculated by subtracting the Data from a predetermined reference value Dref (602). That is, the difference Ddy is the toner density reduced by the development.

Therefore, the CPU 20 executes the Dd created above.
With reference to the y-Ny conversion table Ty, the pulse number Ny of the phase signal to be supplied to the motor driver 21 is determined (60).
3) The Ny pulse phase signal is supplied to the motor driver 21 (604).

Thus, the toner supply motor 22 and the toner supply screw 27 are driven to rotate by Ny steps and stopped. That is, an appropriate amount of toner consumed by the development at this time is supplied to the developing device 8 (60).
5).

As described above, by performing the initial control when the toner cartridge is replaced, an optimum replenishment table is created for each toner filled in the cartridge.

Thus, even when the amount of toner supplied per fixed rotation amount of the toner supply screw is different for each cartridge, replenishment can be performed under optimum conditions, and an appropriate amount of toner particles can always be supplied with high accuracy. In addition, the amount of toner particles in the two-component developer 28 in the container of the developing device 8 can be kept constant.

(Third Embodiment) In the third embodiment, an appropriate amount of toner is used even when the composition of the toner filled in the toner cartridge of the image forming apparatus changes due to a change in the surrounding environment or the like. In order to replenish the toner with high accuracy, when there is a possibility that the toner composition has changed, control is performed to create a table for converting the output voltage value of the magnetic sensor into the rotation amount of the toner replenishment motor. With reference to this, the amount of rotation of the toner supply screw is determined and toner supply is performed.

The outline of the overall configuration of a laser printer as an image forming apparatus according to the present embodiment, and the configuration (for one color) around the toner supply tank are the same as those in the first embodiment (FIG. 1, FIG. 1). 9), the same reference numerals are given, and the description is omitted.

A feature of the image forming apparatus according to the present embodiment is that an allowable error range DrefH to DrefL as shown in FIG. At the end of the operation, the output of the magnetic sensor 25 is checked, and if the value is outside the allowable error range, the output voltage value of the magnetic sensor
That is, control for setting a table to be converted into a rotation amount of 2.

The above control will be described with reference to FIGS. 7 and 8. However, for the sake of simplicity, only control of the yellow developing station will be described below.

In the laser printer of FIG. 1, after the toner supply operation is completed (800), the CPU 20
Output voltage Vatry to the digital value Datary by A / D
Conversion (801).

Next, the CPU 20 determines whether this value Datary is within a predetermined allowable error range (DrefL <
It is determined whether Datary <DrefH is satisfied) (802, 803). If it is within the allowable error range, it is determined that the toner replenishment operation has ended normally and the control is ended (816).

On the other hand, if the value of Datery is not within the predetermined allowable error range, it is determined that the toner composition may have changed and the amount of toner discharged per unit rotation of the toner supply screw may have changed. Perform control.

First, the CPU 20 supplies a phase signal having a predetermined pulse number Nf to the motor driver 21, rotates the toner supply screw 27 by a predetermined amount, and supplies toner into the developing device 8 (804).

As a result, the toner density in the developing device 8 increases, and the value obtained by A / D converting the output voltage of the magnetic sensor 25 becomes D
The status changes from “try” to “try” (805).

Next, the CPU 20 changes Datly 'to D
Atry is reduced to ΔDy (806), and Dy = ΔDy
/ Nf is calculated (807).

That is, when a one-pulse phase signal is sent from the CPU (when the toner supply screw 27 is driven to rotate by one step and the toner is replenished into the developing device 8), the Is increased by Dy.

Therefore, the toner density in the developing device 8 is reduced by the normal printing, and the value obtained by A / D converting the output voltage of the magnetic sensor 25 is changed from the reference value Dref to Da.
When the number of the toner supply screws 27 decreases, the number of steps Ny of the toner supply screw 27 driven to supply the toner to be supplied is reduced.
Can be expressed as (Equation 3).

[0123]

Ny = (Dref-Datry) / Dy = Ddy / Dy

That is, the value Ny converted by (Equation 3)
If the toner supply screw 27 is driven to rotate by the number of steps, the toner consumed by the development is supplied into the developing device 8.

The CPU 20 creates the Ddy-Ny conversion table Ty represented by (Equation 3) and overwrites and stores it in the nonvolatile memory 29 (808).

Next, in step (804), the toner supplied to the developing device 8 is discharged from the developing device 8 to return the toner concentration to the reference value (the value obtained by A / D conversion of the output voltage value of the magnetic sensor 25 becomes The control to make the reference value Dref) will be described below.

First, the CPU 20 causes a laser diode (not shown) to emit light and forms a predetermined electrostatic latent image pattern on the photosensitive drum 5 (809). This electrostatic latent image is visualized by toner in the developing device 8 (81).
0), the image is transferred onto the intermediate transfer body 12 by the transfer roller 9a, and thereafter, is scraped off by the cleaning unit 18. By the above operation, the toner in the developing device 8 is consumed, and the toner density is reduced.

Next, the CPU 20 performs A / D conversion of the output voltage Vatry of the magnetic sensor 25, overwrites the value as Datary (811), and uses the datary as the reference value Dref.
Then, it is determined whether or not the relationship of Datery <Dref is satisfied (812).

At this time, if Datary> Dref, the image for discharging toner is developed again, and
<The above operations (809 to 812) until Dref is satisfied
Continue.

If Datary <Dref, Da
The difference Ddy is calculated by subtracting try from the reference value Dref (813). That is, the difference Ddy is the toner density reduced by the development.

Therefore, the CPU 20 executes the Dd created above.
With reference to the y-Ny conversion table Ty, the pulse number Ny of the phase signal to be supplied to the motor driver 21 is determined (81).
4) The Ny pulse phase signal is supplied to the motor driver 21 (815).

Thus, the toner supply motor 22 and the toner supply screw 27 are driven to rotate by Ny steps and stopped. That is, the toner consumed by the development at this time is supplied into the developing device 8, and the value obtained by A / D converting the output voltage value of the magnetic sensor 25 becomes the reference value Dref (81).
6).

As described above, the output of the magnetic sensor 25 is checked at the end of one toner replenishing operation. Can be controlled to set the table Ty to be converted to

Therefore, for example, due to a change in the surrounding environment, etc.
Even when the fluidity of the toner in the cartridge changes and the amount of toner discharged per unit rotation of the toner supply screw changes, accurate toner supply without causing a supply error can be performed.

The control for replenishing the toner in the developing device 8 after the normal printing is completed by using the Ddy-Ny conversion table Ty created as described above is based on the toner replenishment control described in the second embodiment. Since it is the same as FIG. 6), it will not be described here.

As described above, the output of the magnetic sensor 25 is checked at the end of one toner replenishing operation, and if the value is outside the above-mentioned allowable error range, the initial control is performed. create.

Thus, even when the amount of toner to be replenished per constant rotation amount of the toner replenishing screw varies depending on environmental conditions and the like, replenishment can be performed under optimum conditions, and a proper amount of toner particles can always be obtained with high precision. By replenishing, the amount of toner particles in the two-component developer 28 in the container of the developing device 8 can be kept constant.

As described above, in the first, second, and third embodiments of the present invention, the rotational driving amount of the toner replenishing screw 27 is corrected according to the difference in toner, and 8 has been described.

However, even if the rotation speed of the toner supply screw 27 is corrected and toner is supplied into the developing device 8,
Alternatively, both the rotational driving amount and the rotational speed of the toner replenishing screw 27 are corrected to replenish the toner in the developing device 8,
It is possible to obtain the same effects as the first embodiment, the second embodiment, and the third embodiment of the present invention,
They are not excluded from the scope of the invention.

Further, the first, second, and third embodiments of the present invention can be variously modified based on the spirit of the present invention. Is not excluded from the range.

[0141]

As described above, according to the present invention, toner particles can be replenished under optimum conditions, a proper amount of toner particles can always be replenished with high accuracy, and the two-component developer in the developing container can be replenished. The amount of toner particles inside can be kept constant.

Accordingly, it is possible to provide an image forming apparatus which stably supplies excellent image quality irrespective of the fluidity of toner particles and environmental conditions.

[Brief description of the drawings]

FIG. 1 is a configuration diagram illustrating a toner supply tank and a developing device according to a first embodiment.

FIG. 2 is a diagram illustrating characteristics of a toner fluidity and a discharged toner amount according to the first embodiment.

FIG. 3 is a flowchart illustrating an operation of the image forming apparatus according to the first embodiment.

FIG. 4 is a diagram illustrating characteristics of a concentration of a two-component developer and an output voltage of a magnetic sensor according to a second embodiment.

FIG. 5 is a flowchart illustrating an operation of the image forming apparatus according to the second embodiment.

FIG. 6 is a flowchart illustrating an operation of the image forming apparatus according to the second embodiment.

FIG. 7 is a diagram illustrating characteristics of a developer concentration and a magnetic sensor output voltage according to a third embodiment.

FIG. 8 is a flowchart illustrating an operation of the image forming apparatus according to the third embodiment.

FIG. 9 is an overall configuration diagram showing an image forming apparatus according to a conventional example.

FIG. 10 is a configuration diagram showing a toner supply tank and a developing device according to a conventional example.

FIG. 11 is a flowchart illustrating an operation of the image forming apparatus according to the related art.

FIG. 12 is a diagram illustrating characteristics of a toner fluidity and a discharged toner amount according to a conventional example.

[Explanation of symbols]

 2, 4 Transfer material 5Y, 5M, 5C, 5K Photosensitive drum 7Y, 7M, 7C, 7K Injection charger 7YS, 7MS, 7CS, 7KS Sleeve 8Y, 8M, 8C, 8K Developing device 8YS, 8MS, 8CS, 8KS sleeve 9a Transfer roller 10Y, 10M, 10C, 10K Scanner unit 11Y, 11M, 11C, 11K Toner supply tank 12 Intermediate transfer body 13 Fixing unit 14 Fixing roller 15 Pressure roller 16, 17 Heater 18 Cleaning means 20 CPU 21 Motor driver 22 Pulse motor 23 Reduction gear train 24 Coupling 25 Magnetic sensor 27 Toner supply screw 28 Two-component developer 29 Non-volatile memory

Claims (7)

[Claims] A developing means for visualizing a latent image formed on an image carrier with toner particles using a two-component developer held in a developing container comprising toner particles and carrier particles; A toner particle supply unit for supplying toner particles to a developing container; and a toner particle amount detecting unit for detecting a toner particle amount in a two-component developer in a developing container of the developing unit, wherein the toner particle amount detecting unit A developing device for replenishing the developing unit with a replenishing amount of toner particles based on the detection result of (i), further comprising a control unit for changing the replenishing amount. 2. The developing device according to claim 1, wherein said control means changes said replenishing amount in accordance with the fluidity of the toner particles. 3. The toner particle replenishing means includes: a toner particle conveying means for conveying toner particles; a driving motor for driving the toner particle conveying means; and a rotation of the driving motor based on a detection result of the toner particle amount detecting means. A reference table for converting to a drive amount; and a correction coefficient for a rotational drive amount of the drive motor according to the fluidity of the toner particles. 3. The developing device according to claim 2, wherein the drive motor is rotated by a rotation drive amount multiplied by a correction coefficient based on the fluidity of the toner, and the toner particles are supplied by the toner particle conveying means. 4. The developing device according to claim 1, wherein said toner particle replenishing means is replaceably provided, and said control means changes said replenishing amount when said toner particle replenishing means is replaced. 5. The developing device according to claim 1, wherein said control means changes said replenishing amount when a detection result of said toner particle amount detecting means is out of a predetermined range. 6. The toner particle replenishing means includes: a toner particle conveying means for conveying toner particles; and a drive motor for driving the toner particle conveying means. Calculating a toner particle amount to be supplied to the developing unit by the toner particle conveying unit, and creating a table for converting a detection result of the toner particle amount detecting unit into a rotational drive amount of the drive motor; The developing device according to claim 4, wherein the drive motor is rotated by the determined rotational drive amount, and the toner particles are supplied by the toner particle conveying unit. 7. A developing device according to claim 1, wherein the developing device visualizes a latent image with toner particles, and forms the visualized image on a sheet. Image forming apparatus.