JPH06186842A - Developing method or image forming device - Google Patents

Abstract

PURPOSE:To appropriately consume toner and to always obtain high image quality by controlling the stirring time or stirring speed of developer or forcibly consuming the toner in accordance with the consumption of the toner per unit print. CONSTITUTION:The weight of toner is measured by a weight sensor, and a difference between the measured weight value and a stored value in a previous integrated weight memory part is obtained by a consumption arithmetic part and divided by the specified number of copies to calculate the toner consumption per unit number of copies. The obtained toner consumption is compared with a 1st reference value in a comparison part, and it is successively compared with 2nd and 3rd reference values in the case it is smaller than the 1st reference value. Then, the stirring time of a stirring motor is controlled stepwise by a developer stirring control means so that it may be made shorter than usual or the speed of the stirring motor is controlled to be slow. In the case the toner consumption is smaller than the 3rd reference value, the deteriorated toner is forcibly consumed by a toner forcibly consuming means by judging that the deteriorated toner exists in a developing device.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is incorporated in a developing means of an image forming apparatus for forming a toner image on an image forming body by an electrophotographic method and transferring the toner image onto a transfer material to obtain an image. The present invention relates to a developing method for preventing deterioration of toner that is present and forcibly removing deteriorated toner.

[0002]

2. Description of the Related Art In a developing device that visualizes an electrostatic latent image on an image carrier using a two-component developer consisting of toner and carrier, the weight mixing ratio of toner and carrier in the two-component developer ( Hereinafter, this is referred to as toner concentration T _C ) has a great influence on the developability. For example, if the toner density of the two-component developer is lower than the proper value, the density of the developed image will be low. On the contrary, if the toner density becomes too high, the density of the developed image becomes too high and the so-called fog increases. Therefore, the recorded image on the transfer material transferred from the image carrier becomes unsuitable.

Therefore, in order to always obtain an image having a preferable density, the toner density of the two-component developer is set to an appropriate level,
In addition, it is necessary to keep the appropriate level constant at the time of development. Therefore, a density control method of a two-component developer has been proposed in which the toner density of the two-component developer is kept constant by controlling the toner supply amount.
This density control method detects a change event such as a change in magnetic permeability or a change in volume of a two-component developer, a change in image density after development, and a color change in the two-component developer due to toner and carrier having mutually different colors. Thus, the toner concentration is detected, and the toner replenishment amount is controlled based on the detected toner concentration, so that the toner concentration is maintained at an appropriate level.

However, in the method of detecting a change event as described above, stable operation for a long period of time has been difficult due to reasons such as erroneous detection and difficulty in compensating for deterioration of the photosensitive member surface over time.

As a solution to this problem, Japanese Unexamined Patent Publication (Kokai) No. 57-136669, "Two-Component Developer Concentration Control Device" is introduced. This "two-component developer concentration control device" is a detection level for detecting the volume of the two-component developer in the developing device so that the developing effect in the recording device can be stably maintained and appropriately maintained for a long time. In addition to the above, the density of the developed image of the reference image formed on the surface of the photoconductor or the density of the recorded image is optically detected separately to detect the development performance, and the above-described multiple detections are performed accordingly. The level is switched and set by the central processing unit, and the toner concentration of the two-component developer is controlled in order to avoid carrier replenishment as much as possible and to keep the developing performance as constant as possible. For the time being, the above-mentioned object was achieved.

[0006]

However, the content of an original document to be image-recorded often has a variation in blackening rate due to differences in image density and image density, and blackening of line drawings, character images, low-density originals, etc. When a developing operation is performed to continuously form an image of the original content having a low rate, the predetermined image density corresponding to the toner density cannot be obtained even though the toner density is constant, and the toner The phenomenon that the correspondence between the density and the image density is broken occurs. It was also found that this phenomenon is likely to occur in the case of a color electrostatic recording device which can reproduce a color image by using two-component developers of various colors.

Then, when the cause of such a phenomenon was considered, the following findings were found.

That is, as a result of analyzing the phenomenon common to the above two examples, the developing sleeve and the stirring means in the developing device are continuously driven to rotate within the developing time during the image forming process in the electrostatic recording apparatus. However, it has been found that this stirring time, in other words, the residence time of the two-component developer in the toner hopper, is commonly related. That is, in the former example, since the original is of low density, the toner consumption amount per unit time is smaller than usual, and the toner retention time becomes longer accordingly. In the latter example, the toner consumption amount of the two-component developer for each color is different, and the residence time of the toner is also different for each color.

Considering that the phenomenon of the above example occurs even when the toner concentration is constant, it can be presumed that the phenomenon is not caused by the so-called spent toner in which the toner component is attached around the carrier and the toner charge amount is reduced. However, since it is related to the toner retention time, that is, when the toner retention time becomes longer, it is expected that the toner charge amount will continue to increase due to an increase in the chances of friction between the toner and the carrier. It is considered that the toner charge amount out of the range influences the image density.
Therefore, the relationship between the toner charge amount and the image density was examined.

FIG. 10 is a diagram showing changes in the image density CD with respect to changes in the toner charge amount Q / m (μC / g) when the toner density in the two-component developer is constant.

FIG. 10 shows that the image density CD decreases as the toner charge amount Q / m increases. Specifically, when the toner charge amount Q / m is about 10 (μC / g), the image density CD is about 1.4, and the toner charge amount Q / m is about 30 (μC / g). Image density CD
Indicates about 0.5.

Such image density CD and toner charge amount Q
The relationship with / m will be explained from the force (hereinafter referred to as developing force) that the toner in the two-component developer magnetically carried on the developing sleeve containing the permanent magnet receives in the developing area for developing the electrostatic latent image. it can.

That is, assuming that the developing force is F _t , the developing force F _t is approximately _expressed by [Formula 1] F _t = q _t · E−k (q _t · q _c / r ² ) − q _t (V _B / R) (where q _t is the toner charge amount, E is the electric field due to the electrostatic latent image (hereinafter referred to as the latent image electric field), q _c is the carrier charge amount,
r is the distance between the toner and the carrier, V _B is the voltage applied to the developing sleeve (hereinafter referred to as developing bias), and R is the distance between the photosensitive drum surface and the developing sleeve surface}. .

The developing force F _{t in} Equation 1 is obtained by subtracting the adhesive force between the toner and the carrier (this is called Coulomb force) and the developing bias force acting on the toner from the force caused by the latent image electric field E. Is shown. Here, it should be noted that the force that determines the developing force F _t is the toner charge amount q _t.
Although it is proportional to (Q / m), the Coulomb force, which is a force for reducing the developing force F _t , also increases as the toner charge amount q _t (Q / m) also increases the carrier charge amount q _c. It tends to increase more than the force of. Therefore, increase in the toner charge amount q _t (Q / m) is appears as a decrease in the developing force F _t, decrease in the toner charge amount q _t (Q / m) appears as a rise in the developing force F _t That is the point.

FIG. 10 is a graph showing changes in the image density CD with respect to the toner concentration (wt%: weight mixing ratio) in the two-component developer loaded in the developing device.

Here, the two-component developer has an average particle size of 20 to 10
It is composed of an insulating magnetic carrier (resin coating, magnetic particle resin dispersion type) of 0 μm and a toner having an average particle size of 5 to 15 μm.

In FIG. 10, the solid line A indicates the developing bias V.
_The figure shows the case where _B is 200 V, and the toner concentration is 1 wt.
%, The image density CD is about 0.4, and the toner density is 5w
When t% is exceeded, the image density CD shows about 1.0, and when the toner concentration exceeds 5 wt%, the image density CD is saturated at about 1.2. On the locus of the solid line A, the image density CD is about 0.4 to about 1.2, the contrast is sufficiently wide, the adhesive force between the photosensitive drum, which is the latent image carrier, and the toner is good, and the image shift during the image forming process. Image density C on the locus of solid line A.
It is desired to control D.

The alternate long and short dash line B is, as in the above two examples,
When the time for stirring the two-component developer becomes long and the toner charge amount q _t (Q / m) becomes too large compared to the solid line A, the relationship between the toner concentration T _C (wt%) and the image concentration CD is shown. Shows. The other conditions such as the developing bias V _B are all the same as the solid line A. In this case, as is clear from Equation 1, the Coulomb force increases as compared with the other electrostatic forces, so that the force of attracting the toner to the photosensitive drum is relatively reduced, and the image density is reduced. ing. Specifically, the alternate long and short dash line B indicates that the toner concentration is saturated from 5 wt% to near the image concentration of 0.5. Therefore,
Sufficient image density CD according to the original image on locus B
Cannot be obtained, and further, sufficient contrast cannot be obtained.

The dotted line C indicates the toner density T _C (wt%) and the image density CD when the toner charge amount becomes smaller than the solid line A due to environmental changes such as an increase in relative humidity. Shows the relationship. In this case, it is shown that the adhesive force (Coulomb force) between the toner and the carrier becomes insufficient and the image density CD rises as compared with the solid line A. Specifically, the image density CD is a toner concentration of 1 wt%.
It is shown that the value reaches about 0.7 in the vicinity, and is saturated at about 1.4 as the toner concentration (wt%) increases. Therefore, in the development on the dotted line C, the contrast width has a sufficient width, but a large amount of toner is scattered and too much toner adheres to the latent image, so that the original image is faithfully reproduced. There is a problem that it cannot be put to practical use in terms of reproduction. Further, since the adhesive force between the photosensitive drum and the toner is not sufficient, there is a problem that image shift easily occurs. The present invention solves the problems as described above, so that the toner is properly consumed and a high quality image is always obtained. The developing method includes a step of controlling the charge amount of the toner in the developer within a predetermined range. The purpose is to provide.

[0020]

[Means for Solving the Problems]
It is achieved by any one of b, c and d.

(A) In a developing method in which a two-component developer consisting of a toner and a carrier is stirred by a stirring means, and then the toner image is formed by acting on the electrostatic latent image on the image carrier.
Detecting the consumption amount of the toner per unit print and comparing it with a plurality of reference values, and as a result of the comparison, whether the stirring time or the stirring speed of the two-component developer is at a level to be controlled, and the toner And a step of determining whether it is a level at which the forced consumption of the image is executed.

(B) In the developing method of the image forming apparatus, the consumption amount is detected based on the weight detection of the toner hopper in (a).

(C) In the developing method of the image forming apparatus, the consumption amount is detected based on the weight detection of the waste toner box in (b).

(D) In the developing method of the image forming apparatus, the consumption amount is detected based on the count value of the number of written dots in (c).

[0025]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An image recording apparatus according to an embodiment of the present invention will be described below with reference to FIGS.

FIG. 1 is a block diagram of an image recording apparatus according to an embodiment of the present invention. In the image recording apparatus 100, a photosensitive drum 1, which is a latent image carrier, and a first photosensitive drum 1 are controlled. Motor driver 10, developing device 20, high-voltage power supply 40, transfer device 42, charger 41, scanning optical system 54, first CPU 50, second
CPU 60, optical density measuring means 61, developing bias circuit 62, toner density detecting means 63, stirring motor drive circuit 65, toner box weight detecting sensor 70 in toner hopper 20h,
Exhaust toner box 25 exhaust toner box weight detection sensor
71, toner hopper weight detector 72 and discharged toner weight detector
73 and 73. When a copy button (not shown) is pressed, the scanning optical system is controlled under the control of the first CPU 50.
Based on an image signal corresponding to the image density of the original image from 54, the light source emits light to irradiate the photoconductor drum 1 with light to form an electrostatic latent image on the photoconductor surface of the photoconductor drum 1. The electrostatic latent image is developed by the developing device 20 to be visualized as a toner image, and the transfer device is developed based on the registration signal.
By driving 42 to discharge, the toner image is transferred to a transfer paper. After that, the transfer paper is fixed to form a reproducible image that can be stored.

The photosensitive drum 1 is, for example, an aluminum drum-shaped conductive support having a diameter of 80 mm, and a thickness of 0.1 μm made of an ethylene vinyl acetate copolymer on the support.
OP which is formed by stacking the intermediate layer of
It is a C photoconductor, and when the photosensitive layer is irradiated with light, the surface potential drops. Therefore, if the photoconductor drum 1 is uniformly charged in advance to a predetermined potential and then light based on the density of the original image is irradiated, the surface potential of the photoconductor drum 1 becomes non-uniform and a portion with a lowered potential is formed. You can This is what is called an electrostatic latent image. The photoconductor drum 1 is not limited to this, and may have another structure such as a photoconductor made of amorphous silicon. Here, for convenience of explanation, the above-mentioned OPC photosensitive member will be described.

The first motor driver 10 is a circuit that mainly controls the drive of a main motor (not shown) that rotates the photosensitive drum 1, and based on a control signal from the first CPU 50, the rotation speed and rotation of the main motor. Is on / off controlled.

The encoder 11 generates a pulse signal of a predetermined width corresponding to the rotation phase of the photosensitive drum 1, and the first CPU
Output to 50. As a result, the first CPU 50 detects the rotational phase of the photosensitive drum 1.

As the scanning optical system 54, a well-known scanning system is used in the case of an analog system. For example, although not shown, the first
It consists of an illumination lamp integrated with the scanning mirror, a second scanning mirror (V mirror) that works at a speed ratio of 1/2 of that of the first scanning mirror, etc., and the optical path length in front of the lens was always kept constant. The original is scanned as it is.

In the case of the digital system, the scanning optical system 54 as an image exposing means for forming an electrostatic latent image is a laser provided with a polygon mirror or the like for rotationally scanning a laser from a semiconductor laser modulated by an image signal. Scanning system and L
A fixed scanning system using an ED array or liquid crystal may be used. Here, for convenience of description, an analog scanning optical system will be described below.

The developing device 20 is provided in the lower casing so that a developing tank 20a formed of a lower casing and an upper casing contains a magnet roller 20b having an N pole and an S pole, and a sleeve 20c which is pressed against the sleeve 20c. A regulation member 20d made of a rigid member, screw-shaped first and second stirring rollers 20e and 20f, and a scraper 20g for scraping the two-component developer from the sleeve 20c. The two-component developer is composed of a toner and a carrier, and the toner is attached to the carrier and conveyed to the position of the sleeve 20c, and is conveyed by the sleeve 20c to the developing area opposite to the photosensitive drum 1. Further, in order to supply new toner into the developing tank 20a, it is configured so as to include a conveying screw 20i which communicates with the toner hopper 20h by an internal tube and is driven according to a toner replenishment signal. In addition, instead of the regulating member 20d, a thin layer forming means including a magnetic rod or a magnetic plate may be provided.

The first agitating roller 20e is configured to convey the two-component developer toward the front side of the recording paper, and the second agitating roller 20f is configured to convey the two-component developer toward the inner side of the recording paper. The second CP by the stirring motor drive circuit 65
The developer is controlled to be conveyed at a time designated by U60 or at a designated speed.

Further, the first and second stirring rollers 20e, 20
By providing a partition wall between f, the two-component developer is circulated smoothly and is not locally retained. As a result, the two-component developer conveyed to the developing area can be replaced, and the developing conditions are stabilized.

The scraper 20g is rotatably supported by rollers and is provided so as to come into pressure contact with / separate from the sleeve 20c. At the time of pressure contact, the two-component developer which has passed through the developing area and consumed toner is scraped from the sleeve 20c. .

The sleeve 20c is provided with a developing bias circuit 62 for applying a voltage having an AC bias component and a DC bias component via a protective resistance in order to prevent image fogging. The developing bias circuit 62 removes the toner in the two-component developer that has been conveyed to the developing area by the sleeve 20c.
An electric field generated by an electrostatic latent image formed on the surface of the photosensitive drum 1 is moved by receiving an electrostatic force, and an alternating current for vibrating the toner between the sleeve 20c and the photosensitive drum 1 in the developing area. An AC power supply for applying a bias and a high-voltage DC power supply for applying a DC bias are provided. The developing bias circuit 62 can change the developing bias by a control signal from the second CPU 60, but the toner density is 5.0.
If it is (wt%), the developing bias has a DC component V _DC = -2.
50 (V), AC component peak-to-peak voltage V _PP = 150
The initial settings are 0 (V) and AC frequency f _AC = 3 KH _Z. In this way, the developing bias circuit 62 generates an oscillating electric field between the sleeve 20c and the photosensitive drum 1, and the toner particles vibrate between the sleeve 20c and the photosensitive drum 1, so that the two-component developer is used. It is possible to form a toner image with toner particles on the photosensitive drum 1 efficiently and clearly without contact between the photosensitive drum 1 and the photosensitive drum 1.

The high-voltage power supply circuit 40 includes a transfer device 42 and a charging device 41.
Is a circuit for applying a predetermined high voltage to the.

The optical density measuring means 61 uses an LED as a light source.
The light from the LED reflected by the reference toner image on the photosensitive drum 1 is received by the photodiode.

The toner concentration detecting means 63 is a means for detecting a change in the magnetic permeability of the two-component developer and is for detecting the toner concentration in the two-component developer loaded in the developing device 20. It may be a means for detecting the volume level of the two-component developer in the container 20. Although not limited to these, here, for convenience of description, a toner concentration detecting unit that detects the toner concentration by a change in magnetic permeability will be described.

The toner hopper weight detector 72 is shown in FIG.
As shown in Fig. 5, the pressure change based on the toner weight in the toner hopper 20h is detected by the toner box weight detection sensor 70 using, for example, a piezoelectric sensor, and the weight is calculated. .

Further, the discharged toner weight detection unit 73 detects the total weight of the discharged toner box 25 by a discharged toner box weight detection sensor 71 such as a piezoelectric sensor, and calculates the weight of the discharged toner in the discharged toner box 25. Is. Each of these weight detection sensors 70 and 71 is used when calculating the toner consumption amount.

The first CPU 50 is for controlling the sequence of the image forming process, has an image forming program for executing the image forming process therein, and forms the image by a start signal issued in response to the pressing of the copy button. The program is started to execute the image forming process.

The second CPU 60 controls the developing device 20 and the developer, and inputs the toner weight in the toner hopper 20h from the toner hopper weight detection section 72 or the discharged toner box 71 weight from the discharged toner box weight detection section 73. Perform a calculation to determine the consumption. A stirring table for controlling the stirring motor based on this data is included, which includes a lookup table T showing the relationship between the consumption time and the driving time or speed for controlling the driving time and speed of the stirring motor. A program or the like for giving a control signal to the drive circuit 65 is built in.

The first CPU 50 also includes a first counter CT1 for counting the number of copies and a second counter CT2.
And a third counter CT3 are built-in. The first counter CT1 counts the number of continuous copies at the time of continuous copying in response to a detection signal from a paper discharge sensor or the like, and the second counter CT2 stores a toner charge amount control program. The number of copies indicating the timing of executing, that is, the total number of copies after the previous toner charge amount control is performed is counted. Specifically, the toner charge amount control program is executed every time 1000 copies are made. The third counter CT3 executes the toner charge amount control program and then determines whether or not the image density has returned to the predetermined level by the control, that is, the timing of determining that the toner stirring motor returns to the standard level. The number of copies of the stirring motor control recovery judgment is indicated. Specifically, after executing the toner charge amount control program, it is judged whether or not the image density has recovered to a predetermined level at the time of copying 50 sheets, and based on the judgment, the toner stirring motor control is returned to the initial value. I am trying. Incidentally, these first counter CT1, second counter CT2, and third counter CT3
Is a down counter, the number of continuous copies,
The total number of copies and the number of copies for judgment of bias recovery are set, and these are counted down. When the countdown value becomes "0", each process is performed.

Next, the present invention will be described from the relationship of the toner charge amount with respect to the number of copies.

As described above, if a large amount of continuous copying is continued on a document having a low blackening rate, the charging time of the toner that is not consumed in the developing device 20 becomes long, and the stirring device keeps stirring for a long time. The chances of frictional electrification between the toner and the carrier increase due to conveyance on the developing sleeve, etc., and thereby the charge amount of the toner excessively increases.

FIG. 3 shows these relationships and shows the relationship of the toner charge amount with respect to the copy number separately for the normal case (for an original having a blackening rate) and the case for an original having a low blackening rate. .

In the figure, the curve A represents a normal change in the toner charge amount. The charge amount of the toner in the developing device 20 increases due to copying, and rises due to the replenishment of new toner due to the consumption of this toner. The amount of charge drops. Normally, as described above, the charge amount is controlled within the allowable range of Q1 to Q2 in the figure. Q _{1 to} Q ₂ are in the normal charge amount range.

Curve B represents a case where a document having a low blackening rate is continuously copied, and the toner consumption amount is small, so that the charge amount gradually increases due to stirring and exceeds the allowable range, and the developability also decreases. In this case, the amount of toner consumed is small, and therefore the supply of new toner is small. (In this case, the toner density detection value is within the toner density allowable range) Q3 in the figure is the present invention, when the toner consumption is detected and the consumption exceeds the second reference value (however, the third It shows that the toner charge amount does not exceed the standard value), and when it exceeds this value, the charge amount of the toner decreases by controlling the stirring time of the two-component developer to be short or the stirring speed to be slow. There is.

Similarly, the curve C is a curve showing that the charge amount is lowered by the forcible consumption of toner when the original having a low blackening rate is continuously copied.

In the figure, Q4 is the charge amount when the detected toner consumption amount becomes equal to or less than the third reference value, and at this time, the toner is forcibly consumed, and as a result, the toner charge amount decreases. There is.

Next, the charge amount control and the density control of the toner will be described with reference to the block diagrams of FIGS. 4 and 5.

First, before the image formation by pressing the copy button, it is checked whether or not the actual copy is the total set number. If the total set number is not reached, toner charge amount control,
Density control is not executed.

When the total set number of sheets is reached, the toner charge amount control and density control programs are started. Here, an example of obtaining the toner consumption amount based on the weight of the toner hopper will be described.

As shown in FIG. 4, first, the weight of the toner is measured by the weight sensor, this output is digitally converted by the A / D converter, and the consumption amount calculation unit controls the previous toner charge amount.
Read the integrated toner weight value calculated from the value measured after toner replenishment control of the density control program from the previous integrated weight memory section and take the difference from the memory value of the toner weight value,
This is divided by the specified copy number to calculate the developer consumption amount per unit number of sheets. (In this case, the unit number of sheets is one sheet.) The specified copy may be every 100 copies or every 1000 copies, and the unit copy may be one copy or 100 copies.

The toner consumption amount obtained here is stored in the memory unit and compared with the reference value first in the next comparing unit. If the consumption amount is larger than the first reference value, the problem of toner deterioration does not occur. If it is less, then it is compared with the second reference value. If it is more than this, the developer stirring control means controls the stirring time of the stirring motor to be shorter than usual, or the speed of the stirring motor is changed. Control to slow down.
Further, when the amount is smaller than the second reference value but larger than the third reference value which is smaller than the second reference value, the stirring time is further shortened or the stirring speed is controlled to be slow. Further, when the consumption amount is less than the above three reference values (5 mg / sheet or less), that is, when the toner consumption amount in the developing device 20 is low and the toner is retained in the developing device 20, When it is determined that the deteriorated toner is in the developing device 20, the toner forcible consumption means forcibly consumes the deteriorated toner.

FIG. 2 shows a concrete example in which the control method for the toner consumption amount is divided into four stages and the first reference value is 30 mg /
The second reference value is set to 10 mg / sheet and the third reference value is set to 5 mg / sheet to compare with the actual toner consumption amount. And the control content for toner consumption is 30mg which is the first standard value.
If the number of sheets per sheet or more, the stirring time or stirring speed of the developer is controlled with the standard setting, but the second standard value is 10
When the range is from mg / sheet to 30 mg / sheet of the first reference value, the rotation time of the stirring motor at the standard setting is set to 1/2 or the rotation speed (speed) is set to 1/2 and each is preferably 40 to 6
It is controlled between 0%. Further, when the toner consumption is in the range of 5 mg / sheet of the third reference value to 10 mg / sheet of the second reference value, the rotation time of the stirring motor is 1/3, the rotation speed is 1/3, preferably the standard set. The amount of toner is controlled to 20 to 40%, and when the amount is 5 mg / sheet or less, which is the third standard, about 3 to 10 g of toner is forcibly consumed.

As a concrete means for compulsory consumption, a solid black image is developed on the photosensitive drum 1 so as to be cleaned without being transferred onto the recording paper, and this is repeated several times, and about 3 to 3 as a whole. It consumes 10g.

Here, each of the first, second and third reference values is
It is a value determined in consideration of various factors such as the characteristics of the developer, the characteristics of the developing device 20, the relationship between the exposure amount and the developability, and the reference value is set to three in the embodiment, but it is thinner if more than one is held. It can be controlled. Returning to the block diagram of FIG. 4 again, when it is determined to drive the toner agitation control unit or the forced toner consumption unit, a signal is output to the reset unit to change the toner consumption amount stored in the memory unit. Reset and prepare for toner consumption calculation again.

Next, the toner density control will be described.

As shown in FIG. 5, the toner concentration control is made up of a toner concentration sensor section such as an L detection sensor, a memory section, a comparison section, etc. First, the developer concentration is optimized in the previous step, and then the toner concentration is adjusted. The toner density value is measured by the sensor, converted into digital by the A / D converter, and stored in the memory unit.

Next, the comparison section compares the output voltage according to the toner density with the plurality of reference values to classify the output voltage into levels. The finer this level division, the finer the toner density control.

The toner density signal divided into levels is converted by the next toner replenishment control means into a time corresponding to the level for driving the toner replenishment means, and this time the toner replenishment means is driven to supply the toner to the developing device 20. To do.

As described above, since the replenishment amount of the supply toner is controlled based on the toner concentration according to the toner concentration sensor, the toner concentration in the developing device 20 can be kept constant.

After the toner is completely supplied to the developing device 20, the weight of the developer added for the next check is added to the previous consumption amount memory value, and the value is stored in the memory.

Next, the image recording operation of this image recording apparatus will be described with reference to the flowcharts of FIGS. FIG. 7 is a main flow executed by the first CPU 50.

The power is turned on by pressing the main switch (not shown). As a result, the first and second C
The PUs 50 and 60 are activated (F-1).

The first CPU 50 starts the main motor by driving the first motor driver 10. Second C
The PU 60 drives the first and second stirring rollers 20e and 20f of the developing device 20 by the stirring motor drive circuit to stir the two-component developer. Further, the heater of the fixing device is heated to a predetermined temperature. Further, the first CPU 50 connects the photosensitive drum 1 by the drive system of the main motor to drive the photosensitive drum 1 in rotation, and charges the photosensitive drum 1 with the charger 41 and the static eliminator (not shown). Pretreatment such as adjusting the forming process conditions is performed. Further, in the pre-processing, the number of continuous copies A set by the user by a predetermined button operation is set in the first counter CT1 (F-2).

Further, the second CPU 60 judges whether or not the toner density detection signal from the toner density detecting means TS is always below the set value 5 (wt%) based on the toner density judgment program. When it is less than (wt%), the toner concentration NG signal and when it is not less than (wt%), the toner concentration OK signal No. 2 is stored in the toner concentration determination result register (not shown) of the CPU 60.

Therefore, the second CPU 60 reads the signal set in the toner density determination result register (F-3) and determines whether it is the toner density NG signal (F-).
4). As a result, if the signal is the toner density NG signal, the toner is replenished (F-5) and the process proceeds to step (F-6).
On the other hand, if the toner concentration is OK signal, immediately (F-6)
By determining whether the countdown value in the second counter CT2 is “0”, it is determined whether the count value of the total copy number has reached the total copy number of 1000, which is the setting. to decide. As a result, if the total number of copies has not reached 1000, step (F-9)
Proceed to. If the total number of copies reaches 1000, the first
The CPU 50 sets the total number of copies set to "1000" in the second counter CT2 (F-7) and generates a toner charge amount control interrupt. (F-8). It goes without saying that the set value is not limited to 1000 and may be 100 or 50.

Then, as shown in FIG. 8, in the toner charge amount control interrupt routine, the toner box weight detection sensor is used.
The output (W ₁ ) of 70 is read (F-81). The accumulated toner weight up to the previous time is read from the previous accumulated weight memory (F-
82) For example, the unit consumption amount C per sheet is calculated from these and the specified copy number n (F-83).

Next, the forced developer consumption flag is reset, and the consumption amount C is compared with the first reference value R ₁ (F-83). The consumption amount is greater than or equal to 30 mg / sheet of the first reference value R _1. In this case, there is no problem in the toner charge amount, so the developer stirring time or stirring speed is kept at the standard set mode 0 (F-
85) No particular control is performed. On the other hand, when the consumption amount is less than the first reference value, it causes a problem, so the next step is to compare with the second reference value R ₂ (F-86), and the consumption amount is less than the second reference value R ₂ .
When it is greater than or equal to 10 mg / sheet, the developer stirring time or stirring speed is set to the shortened specification of mode 1 shown in FIG. 2 (F-87). The consumption is the second reference value R
When it is less than ₂ , it is compared with the third reference value R ₃ which is the next step (F-88). When the consumption amount is larger than 5 mg / sheet of the third reference value R ₃ , the developer stirring time or stirring speed is set. Set to the shortened specifications of Mode 2 (F-89). Meanwhile consumption is set in the developer forced consumption flag mode 3 when less than a third reference value R ₃ (F-90). In this way, the toner consumption amount C is determined by the first, second and third reference values R
_It is determined in comparison with ₁ , R ₂ and R ₃ and is set to a mode corresponding to each consumption amount C.

In this routine, when the developer is forcibly consumed, the flag is set, otherwise the developer stirring time is set in the timer register and the process returns.

Then, the first CPU 50 executes the image forming process based on the image forming program. FIG. 7 (F-9). Then, the counter value of the continuous copy number of the first counter CT1 and the counter value of the total copy number of the second counter CT2 are respectively decremented by 1 (F-10), and the counter value of the continuous copy number of the first counter CT1 becomes "0". It is determined whether or not the continuous copy number A related to the setting has been reached (F-11),
When the countdown value of the first counter CT1 is “0” and the continuous copy number A has been reached, the process ends. On the other hand, if the number of continuous copies A has not been reached, the process returns to step (F-3) to make continuous copies for that number.

Here, if the developer compulsory consumption flag is set, the first CPU 50 operates each process and executes the developer compulsory consumption step after the copy process is completed. Actually, a solid black toner image is forcibly developed on the photosensitive drum 1 and is cleaned without being transferred to the transfer material to remove the toner having a large charge amount from the developing device 20.

Next, as another embodiment for obtaining the toner consumption amount, a method of calculating the consumption amount based on the count of the number of writing dots of the laser that exposes the photoconductor of the copying machine will be described.

The digital scanning optical system includes an intensity modulation method and a pulse width modulation method. The intensity modulation method is a method of adjusting the irradiation intensity by adjusting the current passed through the semiconductor laser, for example, and the pulse width modulation method is a method of adjusting the irradiation light amount by adjusting the slice level of the reference wave, for example. is there.

In the present embodiment, the latter pulse width modulation is performed, and as described in the first embodiment, the image density of the original image from the scanning optical system 54 is controlled based on the control of the first CPU 50. The light source emits light based on the image signal to irradiate the photoconductor drum 1 with light to form an electrostatic latent image on the surface of the photoconductor drum 1, and the electrostatic latent image is developed by the developing device 20. To make it visible as a toner image. Therefore, the toner consumption amount can be obtained by integrating the irradiation time to the photoconductor of the laser writing system.

This will be described with reference to the block diagram of FIG. A document read by an image reading system (not shown) is image-processed by an image processing means (not shown) and input as an image signal to the pulse width modulator.

The pulse width modulation section 30 performs a modulation process for changing the light emission time of the reference pixel of the semiconductor laser 31 in the subsequent stage in order to give a gradation to the image signal corresponding to the reference pixel per dot. . The semiconductor laser 31 is laser-modulated based on the image signal modulated by the pulse width modulator 30 and outputs a laser beam which forms an image on the uniformly charged photosensitive drum 1.

By the way, the image signal modulated by the pulse width modulator 30 is input to the counter 32, and the light emission time is counted. In this case, the light emission time of the image signal is counted with reference to the high frequency clock oscillated by the high frequency oscillator 33. The count is accumulated and stored in the memory unit 35 of the toner charge amount control means.

The integrated value may be the count value as it is, or the consumption amount calculation unit 34 multiplies the toner consumption amount per count by the counted value to convert it into the toner consumption amount, which is then integrated and stored. May be.

Then, when the toner charge amount control interrupt is activated, the toner consumption amount based on the integrated value of the light emission time is called, and when it is compared with a plurality of reference values and is smaller than the reference value, the first embodiment is performed. As described based on the explanation, it is judged whether to control the stirring of the developer or to force the toner to be consumed.
The charge amount of the developer is controlled by executing either one.

In this way, the toner consumption amount in the image formation is accurately detected by the consumption amount detecting means, and compared with each of the plurality of reference values described above, if the toner is at a level that prevents the deterioration state, the development stirring is performed. By shortening the stirring time or controlling the stirring speed by a means, the chance of triboelectric charging of the toner is reduced to prevent toner deterioration.

Similarly, the consumed amount is compared with a plurality of reference values, and if the toner is in a deteriorated state, it is determined that the deteriorated toner is in the developing device 20, and this is forcibly consumed by the toner consumption means. Remove.

There is a step of judging the execution of these two, by which the deterioration of the toner is prevented and the deteriorated toner is promptly removed from the inside of the developing device 20.
There is an effect that the toner charge amount in 20 is controlled within a predetermined range to prevent the development performance from being deteriorated thereby, so that a stable developer is always supplied and a good and stable image can be maintained.

Therefore, according to the present invention, since the toner is appropriately consumed and the developing method is provided with the step of controlling the toner charge amount in the developer within a predetermined range, a high quality toner image is always developed.

The present invention can be applied to any mono-black or color image forming apparatus.

[0089]

According to the developing method of the present invention, proper consumption of toner is performed, and the chance of frictional electrification of toner is reduced to prevent toner deterioration.

Further, the toner consumption amount is compared with a plurality of reference values, and if the toner is in a deteriorated level, it is removed from the inside of the developing device by the forced consumption means.

By having the step of judging these two executions, the charge amount of the toner in the developing device is always controlled within a predetermined range and the deterioration of the developing performance is prevented in advance. The image is now developed.

[Brief description of drawings]

FIG. 1 is a block diagram of an image forming apparatus according to an embodiment of the present invention.

FIG. 2 is a table showing a toner consumption amount and a control method according to an embodiment of the present invention.

FIG. 3 is a graph showing a state of toner charge amount with respect to the number of copies.

FIG. 4 is a block diagram showing control of the toner charge amount according to an embodiment of the present invention.

FIG. 5 is a block diagram showing control of toner density.

FIG. 6 is a block diagram for detecting the toner consumption amount by counting the number of written dots.

FIG. 7 is a flowchart showing a main program of a first CPU according to an embodiment of the present invention.

FIG. 8 is a flowchart showing control of the developer charge amount according to an embodiment of the present invention.

FIG. 9 is a graph showing changes in toner charge amount and image density.

FIG. 10 is a graph showing changes in image density with respect to toner density.

[Explanation of symbols]

 1 Photoconductor drum 20 Developer 20h Toner hopper 25 Exhaust toner box 50 First CPU 60 Second CPU 65 Agitating motor drive circuit 70 Toner box weight detection sensor 71 Exhaust toner box weight detection sensor 72 Toner hopper weight detection unit 73 Exhausted toner weight detection unit

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kunihisa Yoshino 2970 Ishikawacho, Hachioji City, Tokyo Konica Stock Company

Claims (4)

[Claims] 1. A developing method in which a two-component developer comprising a toner and a carrier is agitated by an agitating means, and then a toner image is formed by acting on an electrostatic latent image on an image bearing member, per unit print of the toner. The consumption amount of the two-component developer is detected and compared with a plurality of reference values, whether the stirring time or the stirring speed of the two-component developer is controlled, and the forced consumption of the toner is executed. And a step of determining whether or not the level is a level at which the image forming apparatus is developed. 2. The developing method for an image forming apparatus according to claim 1, wherein the consumption amount is detected based on the weight detection of the toner hopper. 3. The developing method for an image forming apparatus according to claim 1, wherein the consumption amount is detected based on the weight detection of the waste toner box. 4. The developing method for an image forming apparatus according to claim 1, wherein the consumption amount is detected based on a count value of the number of written dots.