JP2002349454A - Replenishing amount control method of powder screw pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optimal intermittent driving method in consideration of a characteristic of a powder screw pump, in using the powder screw pump as a device for transporting toner to a developing device in an image forming device of electrophotographic method. SOLUTION: The image forming device has a controlling part 17 for performing control of intermittent driving of the powder screw pump 20 for any unit driving time in intermittently driving the powder screw pump 20. When intermittent driving for a changed unit driving time is performed, the powder screw pump 20 is intermittently driven for a transitional unit driving time different from respective unit driving times before and after the change.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a digital copying machine,
The present invention relates to an improvement in a control method of a powder screw pump used as a toner transfer device in an electrophotographic image forming apparatus such as a printer, a facsimile machine, or a multifunction peripheral thereof.

[0002]

2. Description of the Related Art In an electrophotographic image forming apparatus, an electrostatic latent image formed on an image carrier (photoreceptor) is developed with toner supplied from a developing device, and this toner image is transferred onto transfer paper. An image is formed by transferring and fixing. When the amount of toner in the developing device decreases, a configuration in which toner is supplied to the developing device by a toner transfer device from a toner container located at a position separated from the developing device may be adopted. In addition, there has been conventionally known a cleaning device for removing a residual toner adhered on an image carrier or the like after transferring a toner image on an image carrier onto a transfer sheet by a cleaning blade or the like and collecting the toner. In recent years, effective use of resources and reduction of operating costs have been demanded, and in order to reuse the residual toner collected by the cleaning device, the collected toner is returned to the developing device by the transfer device and mixed with new toner. An image forming apparatus that is reused for forming a toner image on an image carrier again is known (see Japanese Patent Application Laid-Open No. 6-175488). As the above-described toner transfer device, a powder screw pump, commonly called a mono pump, is used as a pump having a high degree of freedom in a transfer path and capable of transferring powder, and further collects toner and air by blowing air from an air pump. There is also known a technique of fluidizing and transferring a mixture in a mixed state (Japanese Patent Laid-Open No.
-73079). In the transfer device of the collected toner using the powder screw pump described above, in order to surely convey the collected toner collected by the cleaning means and conveyed through the tube of the elastic body as an air-fuel mixture with the powder screw pump. Is life, airtightness, temperature rise,
Due to problems such as toner scattering, the powder screw pump is not driven at all times, and is driven (intermittent drive) only when it is detected by the collected toner amount detection means that the collected toner in the toner reservoir reaches a predetermined amount. It has become. Further, when a powder screw pump is used as the collected toner transferring device, when the number of pixels obtained by counting the number of pixels at the time of image formation by the pixel number detecting means reaches a predetermined number, the collected toner in the toner accumulation portion is stored. It has also been proposed to assume that the amount has reached the fixed amount and to perform the intermittent drive so as to omit the collected toner amount detecting means. When a powder screw pump is used as the recovered toner transfer device, the drive is not continuous drive, for example, for 0.1 second or 0.2 second.
.. And intermittent drive control including a unit drive stop time such as 3 seconds or 4 seconds.
That is, for example, by intermittently driving the drive for 0.1 second and stopping the drive for 3 seconds, the control is performed so that a desired amount of toner is replenished to the developing device.

By the way, as the size of the developing device (developing unit) is reduced, the capacity of the developer held inside the developing device is also reduced. In such a small-capacity developing device, the toner concentration of the developer tends to fluctuate remarkably,
Accordingly, in order to always stably secure a sufficient toner supply amount, it is necessary to control the toner supply amount with high precision on the powder screw pump side. However, a method of controlling the toner replenishment amount with high accuracy in relation to the characteristics of the powder screw pump has not been proposed so far. For example, FIG.
Is a replenishment method in which the unit drive time is changed to 0.1, 0.2, and 0.3 seconds while the rotation speed (rpm) of the rotor is kept constant during intermittent drive of the powder screw pump. It is a figure which shows the change of quantity (g). First, when the intermittent driving with the unit driving time of 0.1 second at the start of driving is performed 15 times, the unit driving time is switched to 0.2 second, but the intermittent driving with the unit driving time of 0.1 second is performed. During driving, it is almost stable at the target replenishment amount of 0.04 g. Next, after switching to the unit driving time of 0.2 second,
The target replenishment amount of 0.08 g in intermittent drive in a unit drive time of seconds cannot be reached immediately. In order to reach the target replenishment amount, the target replenishment amount is reached only after passing through a delayed replenishment region including ten intermittent drives. The occurrence of such a delay is the same as in the case of shifting from the unit drive time of 0.2 seconds to the intermittent drive of the unit drive time of 0.3 seconds. Similarly, when the intermittent drive is switched from the long unit drive time (0.2 seconds) to the short unit drive time (0.1 seconds), a rapid decrease in the replenishment amount is not seen, and after passing through the delayed replenishment area. The target supply has been reached. As described above, in switching the unit driving time in the conventional powder screw pump, unless the toner replenishment amount passes through a delayed replenishment region in which the replenishment amount gradually increases or decreases, the target replenishment amount cannot be reached and the stable supply cannot be performed. . In other words, immediately after switching the unit drive time, the toner supply amount follows with good responsiveness, and does not immediately become the supply amount corresponding to the unit drive time after the switch. The phenomenon of stabilizing the quantity occurred. As described above, according to the experiment of the present inventor, if intermittent driving is performed at a different unit driving time after the previous intermittent driving period performed at a certain unit driving time, the powder is It was confirmed that the amount of replenishment was not rapidly increased or decreased due to the effect of the toner remaining in the screw pump.

[0004] When the present inventor pursued the cause of such a phenomenon, the following conclusion was reached. That is, as described above, the powder screw pump accommodates the toner in a sealed gap between the outer periphery of the rotor and the inner wall of the stator, and sends out the toner to the outside by utilizing the pressure generated in the gap when the rotor rotates. Transport mechanism. The amount of toner transferred by the powder screw pump is
This is the amount of movement of the air gap in the stator cross section per unit time. However, when a very fine toner is conveyed, the state (specific gravity, density) of the toner remaining in the powder screw pump when the unit driving time is changed
However, it has been found that this affects the toner replenishment amount at the beginning of intermittent driving due to different unit driving times after switching. The effect of the intermittent drive in the preceding intermittent drive period on the toner supply amount in the intermittent drive mode due to the subsequent different unit drive time is determined until the toner in the powder screw pump is completely discharged from the gap. When the toner in the powder screw pump is completely replaced, the replenishment amount enters the stable region.

[0005]

SUMMARY OF THE INVENTION In order to solve the above-mentioned drawbacks of the prior art, a powder screw pump is used in an electrophotographic image forming apparatus when a powder screw pump is used as a toner transfer device to a developing device. It is an object to propose an optimal intermittent driving method in view of the characteristics of a pump. Specifically, when the unit driving time in the intermittent driving of the powder screw pump is switched, even if the intermittent driving with a different unit driving time is performed after the intermittent driving period with a certain unit driving time, the response is not affected. An object of the present invention is to provide a powder screw pump supply amount control method capable of supplying a target toner supply amount quickly and efficiently. Further, when shifting from the intermittent drive mode with a certain unit drive time to the intermittent drive mode with a different unit drive time, the number of times (X times) of the intermittent drive is performed in the previous intermittent drive mode, so that the intermittent drive after switching is performed. An object of the present invention is to propose an equation that can calculate whether the driving will be adversely affected. In other words, it is an object of the present invention to propose an expression for calculating how many times or less the number of intermittent driving in the preceding intermittent driving mode does not adversely affect the next intermittent driving mode. Also,
If the previous intermittent drive mode for a certain unit drive time exceeds the X times and adversely affects the next intermittent drive mode (reduction in responsiveness when the toner supply amount increases or decreases), the transition is performed immediately before the change. How many times (Y times) intermittent drive is performed with the unit drive time increased (decreased) to reach a stable replenishment amount, or how many times the intermittent drive is performed with the transient unit drive time It is an object to propose a formula for calculating whether or not an error occurs.

[0006]

In order to solve the above-mentioned problems, a first aspect of the present invention is to provide a developing device for supplying a toner to an electrostatic latent image on an image carrier to develop the electrostatic latent image, and to apply a toner to the developing device. An image forming apparatus comprising: a powder screw pump for replenishing; and a control unit for intermittently driving the powder screw pump at an arbitrary unit driving time, wherein the powder screw pump is fixed and axially fixed. A hollow stator having a through hole penetrating through the rotor, a rotor rotatably arranged in the through hole in the stator to form a gap between the inner wall of the stator, and a motor for driving the rotor to rotate. Rotating the rotor to discharge the toner sucked from one end of the through-hole from the other end and replenish the developing device, and the control unit interposes a powder screw pump. When driving, control is performed to intermittently drive the powder screw pump at an arbitrary unit driving time, and when performing intermittent driving with the unit driving time changed, before and after changing the unit driving time, The powder screw pump is intermittently driven at a transient unit drive time having a value different from each unit drive time. In the invention according to claim 2, when the intermittent drive with the unit drive time changed is performed, when the intermittent drive is performed at least X times in the unit drive time before the change, the toner transport efficiency in the intermittent drive mode based on the unit drive time after the change. When the above delay occurs, the above X is expressed by the following equation: X ≧ 60P / nT [P: number of rotor pitches,
n: rotor speed (rpm), T: unit drive time after switching (s)]. According to a third aspect of the present invention, at least X
When performing the intermittent drive with the transient unit drive time after the intermittent drive, the number Y of the intermittent drive by the transient unit drive time is expressed by the following formula: Y ≧ 60P / nT [P: number of rotor pitches, n : Rotor speed (rpm), T: unit drive time after switching (s)] or less.

[0007]

Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic configuration diagram of a digital copying machine according to an embodiment of the present invention, and includes a drum-shaped photosensitive member 1 as an image carrier inside using a well-known electrophotographic method. Around the photoreceptor 1, a charger (scorotron type charger) 2, an exposure unit 3, a developing unit 4, a transfer unit 5, and a cleaning unit 6 for performing an electrophotographic copying process are arranged along a rotation direction indicated by an arrow A. Are located. Charger 2
Is, for example, a scorotron-type charger, which is composed of a casing holding a corona wire and a grid arranged on the opening side of the casing facing the image carrier, and controls the corona discharge of negative charge in the dark by the grid. Thus, the image carrier is charged to a constant potential. Exposure means 3
Is to form an electrostatic latent image by optically writing on the photoreceptor 1 based on an image signal obtained by reading an image of a document placed on a document table 7 on the top of the copying machine by a reading means 8. Yes, LD unit (semiconductor laser light source) 6
1. Polygon motor 62 for rotating polygon mirror, f for scanning and imaging
It comprises a θ lens 63 and a mirror 64. The electrostatic latent image formed on the photoreceptor 1 is formed into a toner image by a developing unit 4, and the toner image is transferred to a transfer sheet (transferred member) fed from a sheet feeding device 9 by a transfer unit 5. Electrotransferred. The transfer paper on which the toner image is placed is conveyed to the fixing unit 10 and fixed, and then discharged outside the apparatus.

Next, the movement of the toner used in the image forming process will be described with reference to FIG. 1 and FIG. 2 showing the image forming section. The developing device 4 is a two-component developing device, and has a developing tank 50 containing a developer including a carrier and a toner. When the developing device 4 supplies the toner onto the photoreceptor 1 to form a toner image, the toner of the developer is consumed, and the ratio (toner density) decreases. Therefore, in order to suppress a decrease in image density, the toner density Vt in the developer is
Is smaller than a predetermined value with respect to the target value Vref of the toner density, the toner is supplied from the toner hopper 51 to maintain the toner density in the developer. The toner concentration in the developer is measured by a magnetic permeability sensor 52 attached to a lower case of the developing device. Target value of toner density Vr
ef is set based on a value Vsp obtained by measuring a measurement toner image (P pattern) formed at an appropriate position on the photoconductor with a photosensor. The toner supplied from the toner hopper 51 via the supply roller 53 is stirred and frictionally charged with the carrier by the stirring member 54 in the developing device 4. The developer including the carrier and the toner is moved by the paddle wheel 55.
It is jumped up to the developing roller 56 and is attracted onto the developing roller 56 by the magnet in the developing roller 56. The developer is conveyed by the sleeve on the outer periphery of the developing roller, and the excess is scraped off by the developing doctor 57. The toner in the developer conveyed to the photoreceptor adheres to the electrostatic latent image due to the developing bias. The toner adhering to the photoreceptor 1 by the above development is electrostatically transferred to transfer paper by the transfer means 5, but about 10% of the toner remains untransferred on the photoreceptor. The untransferred toner is scraped off from the photoreceptor by the cleaning blade 6a and the brush roller 6b of the cleaning means 6, and the scraped-off collected toner is discharged to be reused as recycled toner (T). 6c, falls by its own weight, and is conveyed by the toner guide member 16 (FIG. 3) to the gas flow transfer means as collected toner. The toner guide member 16 also serves as a collected toner transfer path for sending collected toner from the cleaning means 6 to the gas flow transfer means. On the other hand, a cleaning unit 11 is also provided on the transfer belt 5a of the transfer unit 5 to remove toner because the toner adheres to the photoreceptor 1 in the untransferred portion or the non-image portion. The residual toner on the transfer belt 5a is scraped off by a cleaning blade (not shown) that slides on the belt. Since there is a high possibility that the scraped-off toner contains foreign matter such as paper powder, in this example, the scraped toner is dropped by its own weight from the discharge port 5b without being recycled, and is discarded as a collected toner container via the toner guide 18. The toner is sent to the tank 14 (see FIG. 3B).

FIGS. 3 (a) and 3 (b) are an external view of each component supported by a base frame and a main part configuration diagram, and FIG. 4 is a sectional view showing the configuration of a powder screw pump.
A powder screw pump 20 is connected to the toner guide member 16 as a gas flow transfer unit for transferring the toner collected by the photoconductor cleaning unit 6 to the developing unit 4. Powder screw pump 20
The (collected toner transfer device), which is also called a mono pump, conveys the collected toner to the developing unit 4 as a mixture with a gas (air) supplied by a gas supply unit described later. . The powder screw pump 20 includes a stator 22 fixed to a hollow cylindrical holder 21 and having a substantially spiral space therein, and a toner that is recovered in the axial direction by rotating in contact with an inner wall of the stator 22. And a substantially spiral rotor 23 for moving the rotor 23. The stator 22 is arranged so as to form a passage so as to surround the rotor 23. The rotor 23 is engaged with the shaft of the horizontal transport screw 24 at one axial end thereof. The other end of the lateral conveyance screw 24 is engaged with a seal member 25, a bearing 26, and a clutch 27, and transmits a driving force from the image forming apparatus main body to the timing belt 28, the timing pulley 29, and the clutch 2.
7, the rotor 23, the horizontal conveying screw 24
Is driven to rotate. This powder screw pump 20
After the drive is started by the micro processing unit (MPU) 17 as a control unit and the transfer operation of the collected toner is started, the drive unit is rotated and stopped for a predetermined time to stop and the transfer operation of the collected toner is stopped. Then, control is performed such that the collected toner transfer operation is performed intermittently.

The micro processing unit (M
The PU 17 constitutes a control unit (intermittent drive means). The MPU 17 includes a first signal setting unit that sets a first signal when the rotation of the photoconductor 1 (image carrier) starts,
A second signal setting unit that sets a second signal based on the number of pixels of an image formed on the photoconductor 1;
And third signal setting means for setting a third signal based on the D (semiconductor laser) light amount. Also, MPU
Reference numeral 17 denotes an integration of a set value (second signal set value) set by the second signal setting means and a set value (third signal set value) set by the third signal set means. The set value (first signal set value) set by the first signal setting means is added to the value, and the drive of the collected toner transfer device is started after the added value reaches a predetermined value. Perform control. In addition, the MPU 17 starts the driving of the collected toner transfer device, continues the driving of the collected toner transfer device, and stops the drive after a predetermined time has elapsed. In the intermittent drive of the powder screw pump 20 by the MPU 17, for example, as shown in the graph of FIG. 5, the unit drive time is set to 0.1 second and 0.2 while the rotation speed (rpm) of the rotor 23 is kept constant. By switching and changing to seconds, 0.3 seconds,..., The toner supply amount (g) is increased or decreased. In this example, when the intermittent driving with the unit driving time of 0.1 second is performed 15 times, the required number of times of the transient driving with the unit driving time (transient unit driving time) of 0.3 second is performed. Since the replenishment is performed with the unit drive time set to 0.2 seconds, the time required to reach the target toner supply amount when the unit drive time is 0.2 seconds can be significantly reduced.

That is, in this example, a transition is made from an intermittent drive mode with a certain unit drive time (for example, 0.1 seconds) to an intermittent drive mode with a longer unit drive time (for example, 0.2 seconds). When the toner replenishment amount is increased to a predetermined amount (for example, 0.08 g), the unit drive time (0.2 seconds) after the change is multiplied by a predetermined value (1.5 in this example)
By performing the driving in the transient unit driving time (ie, 0.3 seconds), the target toner supply amount (0.08 g) can be increased in a short time. This control method can be similarly applied to a case where a transition is made from intermittent driving with a unit driving time of 0.2 seconds to intermittent driving with a unit driving time of 0.3 seconds.
By switching to the unit driving time of 0.3 seconds after performing the required number of intermittent driving at the transient unit driving time of 1.5 times of 3 seconds, that is, 0.45 seconds, the unit of 0.3 seconds is obtained. It is possible to quickly reach the target toner supply amount of 0.12 g in the case of the driving time. In addition, 1.5 times shown as a multiple of the transient unit drive time used when the unit drive time is changed to increase the toner supply amount is an example, and this value is an example of the individual powder screw pump. Depends on characteristics. Also, a certain unit driving time (for example, 0.3
Seconds) to a shorter unit drive time (eg, 0.2
In this example, when the toner supply amount is reduced by changing the unit drive time to 0.2 seconds, the unit drive time is changed to a predetermined multiple (0.75 times in this example) of the unit drive time (0.2 seconds) after the change. By switching to the time (ie, 0.15 seconds) and performing the required time intermittent drive, and then switching to 0.2 seconds, it is possible to reduce the target toner supply amount to 0.08 g in a short time. Note that 0.75 times, which is a multiple of the case where the unit driving time is changed to reduce the toner supply amount, is:
This is an example, and this value depends on the characteristics of the individual powder screw pump. As described above, by applying the control method of this embodiment at the time of intermittent driving of the powder screw pump, it is possible to increase or decrease the toner supply amount with good responsiveness, and to always supply an appropriate amount of toner in the developing device in a timely manner. Since stable replenishment can be performed (without delay), stable image quality can always be maintained.

Next, when shifting from the intermittent drive mode with a certain unit drive time to the next intermittent drive mode with a different unit drive time, how many times (X times) the intermittent drive should be performed in the previous intermittent drive mode. The following equation (1) can be used to calculate whether or not this will adversely affect intermittent driving after switching. In other words, the following formula is used to calculate how many times or less the number of intermittent drive operations in the previous intermittent drive mode does not adversely affect the next intermittent drive mode. X ≧ 60P / nT (1) [P: rotor pitch number, n: rotor rotation speed (rpm),
T: Unit drive time before switching (s)] The above-mentioned number of times of drive X has an adverse effect on the subsequent intermittent drive performed in a different unit drive time by the preceding intermittent drive mode (response when increasing or decreasing the toner supply amount). If the preceding number of times of driving does not reach X times, it does not reach the extent to which the density of the toner amount in the powder screw pump has an effect. It is not necessary to perform the control using the intermittent drive based on the transient unit drive time as shown in FIG. 5, and it is possible to immediately shift to the intermittent drive based on the next unit drive time. Next, in the switching of the unit driving time in the conventional powder screw pump shown in FIG. 6, since the intermittent driving by the preceding unit driving time is immediately shifted to the intermittent driving by the next unit driving time, it is prompt. Increase / decrease of toner supply could not be realized. In other words, immediately after switching the unit drive time, the toner supply amount follows with good responsiveness, and does not become the supply amount corresponding to the unit drive time after the switch, but the supply amount is delayed by a certain number of drive times. A stable phenomenon occurred. That is, the effect of the intermittent drive in the preceding intermittent drive period on the intermittent drive due to the subsequent different unit drive time is determined until the toner in the powder screw pump is completely discharged from the gap inside the stator (the number of drive times). (Until Y is reached), and when the toner in the powder screw pump is completely replaced, the supply amount enters the stable region.

On the other hand, according to the present invention, as a result of the intermittent driving being performed X times or more in the preceding intermittent driving mode with the predetermined unit driving time, the rise (or fall) of the next intermittent driving is affected. If this occurs, the unit drive time is temporarily increased (or reduced) by a predetermined multiple, and the required number of times of intermittent drive is performed transiently Y times so that the target toner supply amount can be quickly reached. Control. At this time, the number of driving times Y to be performed in the transient unit driving time increased (or decreased) by a predetermined multiple can be obtained by the following equation (2). Y ≧ 60P / nT (2) [P: rotor pitch number, n: rotor speed (rpm),
T: Unit drive time after switching (s)] However, if the number of times of transient driving Y is not limited to a predetermined number, the toner supply amount reaches the target toner supply amount and then exceeds the target toner supply amount, and the supply amount increases ( 5), the intermittent driving is performed at the original next unit driving time at a point in time when the number of times of the transient driving is not exceeded in black in FIG. Therefore, for example, in the transitional drive range when the unit drive time shifts from 0.1 seconds to 0.2 seconds, the toner replenishment amount has already reached 0.08 g in the third (total 18th) drive. Therefore, at this point, the intermittent driving in which the unit driving time is switched to 0.2 seconds may be started. However, if the drive with the unit drive time of 0.3 seconds is continued beyond the ninth (24th in total) drive, the toner supply amount exceeds 0.08 g, so the unit drive time is 0.0
The intermittent driving for 3 seconds is completed at the ninth time (the 24th time in total), and thereafter, the driving with the unit driving time of 0.2 seconds is started. In the above embodiment, the powder screw pump used for the toner recycling mechanism has been described as an example. However, the control method of the present invention is to transfer the new toner stored in the toner container to a developing device at a remote position. The present invention can be applied to a control method of a powder screw pump used at the time.

[0014]

As described above, according to the present invention, when a powder screw pump is used as a toner transfer device to a developing device in an electrophotographic image forming apparatus, it is optimal in view of the characteristics of the powder screw pump. A simple intermittent driving method can be provided. In other words, when switching the unit drive time in the intermittent drive of the powder screw pump, even if the intermittent drive with a different unit drive time is performed after the intermittent drive period with a certain unit drive time, the responsiveness is promptly improved. It is possible to provide a powder screw pump supply amount control method capable of supplying a target toner supply amount to a target. Further, when shifting from the intermittent drive mode with a certain unit drive time to the intermittent drive mode with a different unit drive time, the number of times of intermittent drive in the previous intermittent drive mode adversely affects the intermittent drive after switching. An object of the present invention is to propose an equation that can calculate whether or not to exert an effect. In other words, it is possible to provide an expression for calculating how many times or less the number of intermittent driving in the preceding intermittent driving mode does not adversely affect the next intermittent driving mode. Further, in the case where the previous intermittent drive mode exceeds the X times and adversely affects the next intermittent drive mode, how many times (Y Times)
If intermittent drive is implemented, will it reach a stable supply amount,
Alternatively, it is possible to provide a formula for calculating how many times the intermittent driving is performed if the intermittent driving causes a problem.

[Brief description of the drawings]

FIG. 1 is a schematic diagram illustrating a configuration of an example of an image forming apparatus to which the present invention is applied.

FIG. 2 is an enlarged view of an image forming unit.

FIG. 3 is an external perspective view showing a configuration of each component.

FIG. 4 is an enlarged sectional view of the powder screw pump.

FIG. 5 is a diagram illustrating a control method according to an embodiment of the present invention.

FIG. 6 is a diagram illustrating a conventional control method.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 drum-shaped photoreceptor (image carrier), 2 charger (Scottron type charger), 3 exposing means (LD), 4 developing means, 5 transferring means, 6 cleaning means, 7 original mounting table, 8 reading means, 9 Paper feeder, 10 fixing unit, 11 cleaning unit, 14 tank, 16 toner guide member, 17 MPU (control unit, intermittent drive unit), 20 powder screw pump, 21 holder, 2
2 Stator, 23 rotor, 24 horizontal conveying screw, 25 seal member, 26 bearing, 27 clutch,
28 Timing belt, 29 Timing pulley, 5
0 developing tank, 51 toner hopper, 52 magnetic permeability sensor, 53 replenishing roller, 54 stirring member, 55 paddle wheel, 56 developing roller, 57 developing doctor

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) G03G 15/08 507 G03G 15/08 507D // G03G 21/10 21/00 326 F term (reference) 2H077 AA15 AA20 AA37 AB06 AB14 AC03 AC11 AD06 AD13 AD23 AE06 BA01 DA03 DA10 DA42 DA47 DA52 DB01 DB14 EA03 2H134 GA01 GA05 GB01 HB00 HD00 JA02 JA03 JA11 JA14 JC02 KB11 3F047 AA11 AB03 CA02 CA15 CC09 CC11 3H041 AA00 BB06 CC22 DD02 DD05 DD07 DD07 DD03 DD00 DD31

Claims (3)

[Claims] A developing device for supplying toner to an electrostatic latent image on an image carrier to develop the electrostatic latent image; a powder screw pump for replenishing the developing device with toner; A control unit for intermittently driving the unit in a unit driving time, wherein the powder screw pump is fixed and has a hollow stator having a through-hole penetrating in the axial direction; A rotor rotatably arranged in the hole to form a gap between the inner wall of the stator and a motor for driving the rotor to rotate; the rotor is rotated to suck from one end of the through hole. A controller configured to discharge the toner from the other end and supply the toner to the developing device; wherein the controller controls the powder screw pump at an arbitrary unit driving time when the powder screw pump is intermittently driven. If the performed control of intermittently driving, the intermittent driving for changing the unit driving time,
Before changing the unit drive time, the powder screw pump is intermittently driven with a transient unit drive time having a value different from each unit drive time before and after the change, and the replenishment amount control of the powder screw pump is characterized in that Method. 2. When performing intermittent driving in which the unit driving time is changed, when intermittent driving is performed at least X times in the unit driving time before the change, in the intermittent driving mode based on the unit driving time after the change, the toner transport efficiency is reduced. When a delay occurs, X is expressed by the following expression: X ≧ 60P / nT [P: rotor pitch number, n: rotor rotation speed (rpm),
T: Unit drive time after switching (s)], and the supply amount control method of the powder screw pump according to claim 1. 3. When performing intermittent driving at the transitional unit driving time after performing at least X intermittent driving at the unit driving time before the change, the number of intermittent drivings Y by the transitional unit driving time is performed. Is expressed by the following formula: Y ≧ 60P / nT [P: rotor pitch number, n: rotor rotation speed (rpm),
3. The method according to claim 1, wherein the number of times is determined to be equal to or less than a number determined by a unit driving time (s) after switching.