JP2000172076A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make the occurrence of toner clogging possible to be prevented, and to prevent aggregation or stick of the toner in the toner transferring tube by driving a powder pump reverse for the specified time, after stopping performing the toner replenishment to the developing device by forward driving the powder pump. SOLUTION: This image forming device is provided with a motor 46 making a rotor 42 possible to be rotated forward and backward, and the stepping motor and the servomotor making the rotary direction thereof possible to be controlled. The device is allowed to perform the drive controlling the motor 46 of the screw pump 41 and the air pump by the controlling device equipped with a MPU. From the MPU, forward/backward rotation signal is also transmitted and the rotary direction thereof is designated. The forward rotation is the rotary direction for attracting the toner, and the reverse rotation is the rotary direction for returning the toner remaining in a tube 15 into the toner container. By reversally driving a screw pump 41 right after stopping the drive, the residual toner in the tube 15 still keeping flow property is transferred in the reverse direction namely, into the toner container, therefore the residual toner in the tube 15 can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing device for developing a latent image formed on an image carrier with powder toner, a toner storing means provided separately from the developing device, and the toner storing means. The present invention relates to an electrophotographic image forming apparatus comprising: a suction type powder pump means for sucking toner stored in a developing device and transferring the toner to the developing device.

[0002]

2. Description of the Related Art Conventionally, in an image forming apparatus such as a copying machine or a printer, toner is consumed by use and thus needs to be replenished appropriately. For this reason, a toner storage means such as a toner bottle or a cartridge storing a large amount of toner is provided in the machine, and the toner is supplied from the toner storage means to the developing device directly or via a toner hopper. ing. Many of the conventional toner transfer techniques are based on mechanical auger means, and the toner container has to be installed integrally or very close to the developing device. This complicates the structure of the toner replenishing device, hinders high cost, low productivity and mechanical maintenance, makes it difficult to secure and maintain the toner quality characteristics, and also requires the user to replace the toner container. There was also difficulty in sex.

Further, since the conventional toner container is made of a hard bottle such as a cartridge or a bottle, there has been a great problem in discarding the used container accompanying the replacement of the toner container. That is, the used toner storage container is collected by the manufacturer from the user, and is recycled, reused, and incinerated. However, the container is bulky and requires a high distribution cost until it is collected.

[0004] The applicant of the present invention has proposed a toner replenishing apparatus using a powder pump in which such problems are unlikely to occur. As a powder pump of this device, a single-axis eccentric screw pump called a mono pump formed of a female screw type stator having a double pitch spiral groove therein, and a male screw type rotor rotatably fitted in the stator. Is used to transfer the toner. In this transfer method, the stored toner can be transferred via a flexible tube or the like, so that the installation position of the toner storage unit is not restricted at all, and the toner can be reliably transferred with a simple configuration. There is. In addition, a toner transfer device using a screw pump is provided with an air supply means, and is fluidized in a gaseous mixture state with air and transferred in a state, so that stable transfer of toner can be obtained and the toner to be transferred. Aggregation, thermal fusion, and the like of the transferred toner are less likely to occur without further applying unnecessary stress.

[0005] Under such circumstances, it is understood that the toner transfer system using the screw pump is particularly excellent.

[Problems to be solved by the invention]

However, there is no problem at all in a toner transfer system using a screw pump. In such a method, the toner can be transferred through a hollow tube made of rubber or the like, but the toner often remains in the tube when the machine is stopped, and this toner is left for a long time. In this case, when bad conditions such as vibration and heat are applied, the toner is agglomerated and fixed, and there is a problem that toner clogging occurs.

The present invention solves the above-mentioned conventional problems,
It is an object of the present invention to provide an image forming apparatus that prevents aggregation and fixation of toner in a toner transfer pipe and hardly causes toner clogging.

[0008]

In order to achieve the above object, the present invention provides a developing device for developing a latent image formed on an image carrier with powder toner, and a developing device provided separately from the developing device. An image forming apparatus comprising: a toner accommodating unit; and a suction type powder pump unit for sucking the toner accommodated in the toner accommodating unit and transferring the toner to the developing device. A driving unit capable of reverse rotation is provided, wherein the powder pump unit is rotated forward by the driving unit, supplies toner to the developing device and stops, and is thereafter driven in reverse rotation for a predetermined time.

In the present invention, the powder pump means may include:
A female screw type stator having a double pitch spiral groove therein, and a male screw type rotor rotatably fitted in the stator, and rotating the rotor to form toner along the axial direction of the rotor. Is a suction type uniaxial eccentric screw pump capable of moving the toner, wherein the screw pump is connected to the toner storage means via a toner transfer pipe, and the toner in the toner storage means is diffused. It is effective to provide an air supply means for fluidizing the fluid.

Further, according to the present invention, when supplying the toner in the toner storage unit to the developing device, the air supply unit is driven before the screw pump is driven, and the air supply unit is stopped before the screw pump is stopped. It is effective to stop driving the means.

Still further, according to the present invention, it is preferable that the reverse rotation drive of the powder pump is performed after the end of the continuous replenishment only when the powder pump means is considered to continuously supply the toner within a predetermined time. It is a target.

Further, the present invention is effective when the powder pump means is provided on the developing device side and is located above a toner supply section of the developing device.

[0013]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a configuration diagram of the agent supply device according to the present invention.

In FIG. 1, the agent replenishing device of the present embodiment replenishes toner to the developing device 10, and includes a toner container 20 serving as a storing means for storing toner, and a toner container 20 stored in the toner container 20. And a powder pump means 40 for transferring the toner to the developing device 10.

As shown in FIGS. 1 to 4, the developing device 10 includes a developing sleeve 11 as a developer carrying member arranged opposite to the photosensitive member 1 as an image carrying member, and an axis line with the developing sleeve 11. A first stirring screw 12 and a second stirring screw 13 are provided as parallel conveying members. The developer in the developing device 10 is circulated so as to be conveyed from left to right in FIG. 2 by the first stirring screw 12 and from right to left by the second stirring screw 13. During this circulation, the electrostatic latent image formed on the photoconductor 1 is developed with the toner of the developer transferred to the developing sleeve 11 in the middle of the transport path.

As shown in FIGS. 2 to 4, the developing device 10 is provided with a powder pump means 40 at a front end portion of the developing apparatus. The powder pump means 40 includes a suction type uniaxial eccentric screw pump 41. I have it. The configuration of the screw pump 41 is such that a rotor 42 formed in an eccentric screw shape with a rigid material such as a metal, and a two-screw shape formed on the inside with an elastic body such as rubber are fixed and installed. It has a stator 43 and a holder 44 made of a resin material or the like that wraps the stator 43 and forms a powder conveyance path. Reference numeral 46 denotes a motor as driving means for driving the rotor 42. As the motor 46, a stepping motor, a servo motor, or the like, which is capable of normal rotation and reverse rotation and whose rotation direction can be controlled, is used.

The developing device 10 includes a magnetic permeability detector 18.
The detector 18 detects a change in the mixing ratio of the toner and the carrier in the developing device 10. When the magnetic permeability detector 18 detects that the amount of toner is small, the motor 46 rotates forward and the uniaxial eccentric screw pump 41 is operated so that the toner in the toner container 20 is sucked and supplied. Is done. When the concentration of the developer in the developing device 10 reaches a predetermined concentration, the motor 4
6 is turned off, and the toner supply is stopped. In addition,
The developing device 10 may adopt a method of detecting the reflection density of the toner image formed on the photoconductor and controlling the toner supply amount.

The screw pump 41 includes a rotor 42
A strong self-suction force is generated by the rotation of, and toner can be sucked from the toner storage container 20. The sucked-in toner is transferred into the developing device 10 by the supply hole 17 formed between the screw pump 41 and the first stirring screw 12, and during the transfer process when the two-component developing system is used. The toner replenished with the developer is mixed with the developer in the developing device 10 with stirring, so that a uniform developer concentration and an appropriate charge amount are obtained. The developing device includes a deaeration hole 14a and the deaeration hole 14a.
a is provided, and air transported together with the toner is degassed from the developing device 10.
It is configured to prevent the toner from scattering. The tube 15 as a toner transfer pipe connected to the suction part of the single-axis eccentric screw pump 41 has a diameter of, for example, 4 to 10 m.
It is extremely effective to use a tube made of a rubber material (for example, polyurethane, nitrile, EPDM, silicone, etc.) which is tube-shaped and has a wall thickness of about 1 to 2 mm and is flexible and has excellent toner resistance. It is.

If the flexible tube 15 is used as the toner transfer tube, the restriction on the installation of the toner container 20 with respect to the developing device 10 is reduced, the installation place is effectively used, and the workability such as machine maintenance is improved. I do. The suction amount of the screw pump 41 is
The screw pump 41 used in the present embodiment has a performance of a toner suction distance of about 1 m, depending on the rotation speed of the rotor, the cross-sectional area and the amount of eccentricity of the rotor 42, the fluidity of the toner, and the like. The direction can be freely selected in any direction up, down, left, and right.

FIG. 5 is an explanatory sectional view showing an embodiment of the toner container 20 and an air pump 50 as air supply means. In FIG. 5, the toner storage means 20 has a storage container main body 21 formed in a bag shape, and a suction guide member 22 as a pipe-shaped agent guide member and an ultrasonic wave or the like at the upper center of the storage container main body 21. Welded,
They are integrally connected. This suction guide member 22
The lower end reaches near the bottom of the storage container main body 21, and the upper end protrudes from the storage container main body 21, and a threaded portion 23 as an engaging portion is formed at the exposed portion. The screw portion 23 is detachably screwed to an air intake portion 25 and a screw portion of a base member 24 to which one end of the tube 15 is detachably connected. Reference numeral 29 denotes a packing made of a rubber material or the like, and has a role of completely sealing the outer peripheral side of the toner conduction path 26 of the suction guide member 22 and the toner conduction hole 28 of the base member 24 when engaged. The suction guide member 22 is provided with an air passage 27 on the outer periphery of the toner passage 26.

The storage container body 21 is made of a resin such as polyethylene or nylon, and is made of a flexible sheet having a thickness of about 80 to 120 μm in a single-layer or multilayer structure. In addition, it is effective to deal with static electricity by subjecting the surface of these sheets to aluminum vapor deposition. Further, the suction guide member 22 can also be made of resin such as polyethylene or nylon, and if it is set to the same material as the storage container body 21, it is convenient for recycling. The suction guide member 22 corresponds to a toner suction port, but also functions as a toner filling port in a factory.

The toner used in the electrophotographic image forming apparatus has very poor fluidity. For this reason, in this embodiment, the storage container main body 21 is placed vertically, and the lower end of the pipe-shaped suction guide member 22 is disposed so as to reach a position near the bottom thereof. The toner is sucked from the tip of the suction guide member 22 by the screw pump 41.

When toner is supplied using the screw pump 41, it is important to fluidize the toner by air. If the toner is not fluidized, the toner in the vicinity of the bottom of the toner container 20 does not flow stably to the pipe-shaped suction guide member 22, so that the transfer of the toner becomes uncertain.

Therefore, the toner storage container 20 is supplied with 0.5 to 1
Air is blown at a rate of about 1 liter / minute. This air passes through the air passage 27 and is ejected near the bottom of the toner container 20 where the toner is stored, thereby directly fluidizing the toner layer. The fluidization of the air prevents the occurrence of a cross-linking phenomenon and the like, and ensures the transfer of the toner. Further, since there is no occurrence of toner agglomeration, the physical properties of the toner are always stable, and high-quality development quality can be obtained. A part of the air blown into the toner storage container 20 is sent to the developing device 10 together with the toner, and the other air goes outside through the opening 31 closed by the air filter 32.

Since the storage container body 21 is flexible, the volume in the bag is reduced as the suction of toner proceeds, but the suction guide member 22 causes local deformation when the storage container body 21 is reduced in volume. Is suppressed, and the stored toner can be discharged without remaining in the bag. Further, the bottom of the bag-shaped storage container main body 21 has an inverted conical shape 30, and even if the amount of stored toner is small, the toner naturally falls due to the weight of the toner and is transferred to the suction port of the suction guide member 22. Thus, stable toner transfer can be achieved regardless of the amount of stored toner.

Whether or not the air pump 50 is operated to supply air to the toner container 20 can be detected by the air detector 54. This air detector 54 is provided with a transparent tube 52 extending vertically at an arbitrary position of an air tube 51 connecting between the air pump 50 and the air intake 25, and floats in the transparent tube 52 by air. A resin or metal float 53 is enclosed. When the float 53 is lifted by the air, it is detected by the air detector 54, and it can be seen that the air is supplied. Here, the air pump 50
If the air supply is not supplied in spite of the issuance of the operation command, it is determined that some abnormality has occurred in the air supply, the operation command to the air pump 50 is released, and the image forming apparatus is released. It is preferable to stop the operation and display the occurrence of a failure.

The toner replenishing apparatus of the present embodiment employs a screw pump 4 by a control device having an MPU shown in FIG.
The drive and control of the first motor 46 and the air pump 50 are performed. Toner density sensor provided in part of developing device 10
(Magnetic permeability detector) 18 detects a change in the mixing ratio of the toner and the carrier in the developing device, and the result of the detection is taken into the MPU. When it is detected that the toner amount is small as a result of the detection, an ON / OFF signal is transmitted from the MPU to the motor 46 (M in FIG. 6) via the driver.
The operation of replenishing toner from the toner storage container 20 to the developing device 10 is performed. At the same time, a normal rotation / reverse rotation signal is also transmitted from the MPU, and its rotation direction is designated. The forward rotation is a rotation direction for sucking the toner, and the reverse rotation is a rotation direction for returning the toner remaining in the tube 15 into the toner storage container 20.

The MPU has a timer function, and can control the driving of a drive motor, an air pump, and the like at an arbitrary timing. Further, as described above, the signal of the air detector 54 is taken in, and when an abnormality is detected, the driving of the screw pump is stopped.

FIG. 7 is a diagram showing the detailed control timing of the screw pump 41 and the air pump 50 by the control device. The control timing is referred to as a supply mode.
As described above, the ON / OFF signal is sent to the motor 46 of the screw pump 41 for a predetermined time (several seconds) based on the output result of the toner density sensor 18 (1), and at the same time, the forward rotation signal is sent (2). 41 is driven in a forward rotation for several seconds (3). When the forward rotation of the screw pump drive motor for a predetermined time is completed, the motor 46 of the screw pump 41 is fixed for a certain time, for example, 0.5 seconds.
Signal is sent to the screw pump 41 during this time.
Stops. Subsequently, the motor 4 of the screw pump 41
An ON signal and a reverse rotation signal are output to 6, and the screw pump 41 performs reverse rotation. Further, the air pump 50 is controlled such that when the motor 46 of the screw pump 41 starts to be driven, only the air pump 50 is operated immediately before the start of the operation.
After 5 to 1 second, the motor 4 of the screw pump 41
6 when the air pump 50 is stopped, at the same time as when the motor 46 of the screw pump 41 is stopped, or 0.5 to 1 second before the stop.

By controlling in this manner, as shown in FIG. 8, while the screw pump 41 is operating, the toner substantially uniformly mixed with air fills substantially the entire area of the tube 15. Therefore, if the screw pump 41 is stopped, the toner remains in the tube 15 as it is.
Thereafter, only air escapes from the air-mixed toner filling the tube 15 due to long-term storage, and as shown in FIG. 9, the toner 15 sinks downward by its own weight, so that the bulk density of the toner increases. In such a state, external vibration,
When bad conditions such as heat are given, air in the toner is further released, and the toner may be aggregated or the toner may be easily fixed.

When such toner aggregation or sticking occurs, the screw pump 41 is operated again,
When the toner is transferred, the transfer of the toner is blocked by the high bulk density toner remaining in the tube 15, and the toner may be clogged in the tube 15. As a result, the screw pump 41 May lock or burn (excessive rise in temperature causes toner to adhere to the rotor 302, and the adhered toner scrapes the stator 303, causing damage to the pump, etc.).

Further, when toner agglomeration or sticking occurs, the space between the rotor 42 and the stator 43 of the screw pump 41 is full of toner when the apparatus is stopped, so that stress is generated in the rubber stator 43. If the standing time is long, permanent distortion of the stator 43 occurs, and the bite between the rotor 42 and the stator 43 is reduced, which may cause a problem that the suction force of the screw pump 41 is reduced.

On the other hand, as described above, by driving the screw pump 41 in the reverse rotation immediately after the operation is stopped, the toner remaining in the tube 15 can be transferred to a state with good fluidity during the transfer. Before the bulk density of the toner is increased), the toner is transferred in the opposite direction,
As shown in FIG. 10, the remaining toner in the tube 15 can be reduced.

Therefore, according to the present embodiment, the clogging of the toner in the tube 15 as described above can be eliminated, and the transfer of the toner can be made more reliable. Further, since almost no toner enters the screw pump 41 at the time of stop, permanent distortion of the stator 43 during long-term standing can be prevented.
1 can be extended.

In the image forming apparatus, a relatively large amount of toner may be consumed in a short time. At this time, since toner replenishment is performed several times continuously in a short time, if the screw pump 41 is driven in reverse rotation immediately after the operation is stopped for each toner replenishment, a situation may occur in which the toner replenishment command cannot be responded. There is.

Therefore, in the present invention, when it is considered that toner replenishment is performed several times continuously in a short time, after the continuous replenishment is completed, the screw pump 41 is driven to rotate in the reverse direction immediately after the operation is stopped. I have to.

FIG. 11 shows an example of this. In the case of continuous printing of a predetermined number of sheets (n sheets) or less, the above control method is performed. In addition, in the case of continuous printing of n or more sheets, the screw pump is rotated only after the printing is completed. 5 shows a control flowchart for performing a mode.

When a drive signal is sent to the main motor, processing from the start to the end of the drawing is performed. Here, the continuous printing operation for n sheets is determined based on the initial setting number operated by the user. In the case of n or less continuous printing, the supply mode control of FIG. 7 is performed. In the case of continuous printing of n or more sheets, the supply mode control shown in FIG. 12 is performed, and when the continuous printing of n sheets is completed, the process proceeds to the reverse rotation mode. Here, the reverse rotation mode means that the screw pump 41 performs reverse rotation (with respect to the rotation direction at the time of toner suction) for a predetermined time as shown in FIG.

FIG. 12 shows the detailed control timing of the screw pump 41 and the air pump 50 by the control device during continuous printing of n or more sheets (supply mode + reverse mode).

In FIG. 12, the motor 46 of the screw pump 41 is turned on according to the output result of the toner density sensor.
/ OFF and forward / reverse signals are sent to the screw pump 4
1 is driven in the designated rotation direction. The rotation direction is the same as that described above, ie, the rotation direction in which toner suction is performed, and the reverse
5 is a rotation direction such that the residual toner inside is reversely transferred into the toner storage container 20. Here, the drive start time of the air pump 50 is operated by a fixed time, for example, 0.5 seconds earlier than the screw pump 41, and is stopped simultaneously with the screw pump. When the printing of n sheets is completed and the reverse rotation mode is entered, a reverse rotation signal is output together with an ON signal to the motor 41 of the screw pump 41,
The screw pump 41 performs reverse rotation for a predetermined time (for example, about 5 seconds). By doing so, when the continuous printing operation is completed, the residual toner in the transfer member and the screw pump 41 can be reduced as described above, the toner clogging in the tube 15 is eliminated, and the screw pump 4
1 can also be improved in durability.

In the above-described embodiment, it is determined that toner replenishment is continuously performed according to the number of prints. As described above, the preferred embodiments of the present invention have been described. However, the present invention is not limited to the above embodiments, and can be variously modified.

For example, the agent storage container is not limited to toner, but may be a container for storing a developer, and this developer may be supplied to the developing means. Further, the configuration of the developing means to which the toner is supplied may be arbitrary, and the present invention can be applied to an apparatus using a one-component developer instead of a two-component developer as in the above-described embodiment.

[0043]

According to the above configuration, the clogging of the toner in the toner transfer pipe can be surely eliminated, and the transfer of the toner can be made more reliable. Furthermore, since it is possible to make the state in which almost no toner enters the powder pump at the time of stoppage, it is possible to prevent permanent distortion of the stator when left for a long period of time.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram for explaining a configuration of the present invention.

FIG. 2 is a cross-sectional view illustrating a toner receiving unit of the developing device.

FIG. 3 is a plan view showing a part of the developing device.

FIG. 4 is an external side view of the developing device.

FIG. 5 is a sectional view of the toner storage means.

FIG. 6 is a control system block diagram of the toner supply mechanism of the present invention.

FIG. 7 is a diagram showing operation timings of the powder pump and the air pump of the present invention.

FIG. 8 is an explanatory sectional view showing a state inside the tube and the powder pump when the powder pump is stopped.

FIG. 9 is an explanatory cross-sectional view showing a state in which the powder pump is not rotated reversely after the powder pump is stopped.

FIG. 10 is an explanatory sectional view showing a state after the powder pump is reversed after the powder pump is stopped.

FIG. 11 is a control flowchart of the toner supply mechanism of the present invention.

FIG. 12 is a diagram showing operation timings of a powder pump and an air pump according to another embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Photoreceptor drum 10 Developing means 20 Toner storage container 15 Tube 41 Screw pump 46 Motor 50 Air pump

Claims (5)

[Claims] 1. A developing device for developing a latent image formed on an image carrier with a powder toner, a toner storage unit provided separately from the developing device, and a toner storage unit provided in the toner storage unit. An image forming apparatus comprising: a suction-type powder pump unit for sucking and transferring the powder to the developing device; and a driving unit capable of driving the powder pump unit to rotate forward and reverse. An image forming apparatus characterized in that the image forming apparatus is rotated in a normal direction by the driving means, supplies toner to the developing device and stops, and then is driven in a reverse direction for a predetermined time. 2. The image forming apparatus according to claim 1, wherein said powder pump means is internally threaded with a double pitch spiral groove therein, and is rotatably fitted into said stator. A suction-type single-shaft eccentric screw pump having an externally threaded rotor and capable of moving toner along the axial direction of the rotor by rotating the rotor, wherein the screw pump is connected via a toner transfer pipe; An agent storage container which is connected to the toner storage unit and is provided with an air supply unit for fluidizing the toner in the toner storage unit in a diffused state. 3. The image forming apparatus according to claim 2, wherein when supplying the toner in the toner storage unit to the developing device, the air supply unit is driven prior to the driving of the screw pump. An image forming apparatus, wherein the driving of the air supply unit is stopped before the driving is stopped. 4. The reverse rotation drive of the powder pump is performed after the continuous replenishment is completed only when it is determined that the powder pump means continuously supplies toner within a predetermined time. 4. The image forming apparatus according to any one of 3. to 3. 5. The image forming apparatus according to claim 1, wherein said powder pump means is provided on said developing device side, and is located above a toner replenishing section of said developing device. An image forming apparatus.