JP2009053274A - Developing device, process cartridge, and image forming apparatus - Google Patents

Abstract

A developing device, a process cartridge, and an image forming device capable of effectively preventing clogging of a filter provided to eliminate toner ejection caused by an increase in internal pressure accompanying operation of the developing device. Providing equipment.
A developing device having agent transport screws (5, 6) for stirring and transporting a developer in a case (4) and a developing roller (7) disposed in an opening of the case and facing an image carrier, The vent hole 10 provided in the case is provided with a depressurizing filter 11 and clogging eliminating means 20 for vibrating the depressurizing filter.
[Selection] Figure 2

Description

  The present invention relates to an improvement of a developing device provided in an electrophotographic image forming apparatus such as a copying machine, a facsimile, or a printer.

  As a developing device equipped in an electrophotographic image forming apparatus such as a copying machine, a facsimile machine, or a printer, a two-component developer is placed in a developing case and charged while stirring and transporting the two-component developer. The type is known. In such a developing device, an air flow is generated by the magnetic brush on the developing roller when the developing roller disposed opposite to the image carrier rotates, so that the pressure inside the developing device becomes higher than the external pressure. . Further, since the toner and the carrier constituting the two-component developer have particle sizes of about 10 [μm] and 50 [μm] or less, respectively, the end of the developing device case and the developing roller due to a pressure difference between the inside and outside of the developing device It is known that toner is ejected from a gap between the image forming apparatus and the inside of the image forming apparatus and recording paper.

In the past, measures to prevent toner ejection have been taken by reducing the internal pressure with a filter disposed in a vent hole provided in the developing device case. In Japanese Patent Laid-Open No. 2005-352076, a filter replaceable with the case of the developing device. A ventilation duct equipped with is provided to prevent the internal pressure from rising. In Japanese Patent Application Laid-Open No. 6-59550, only when the toner density at the time of image formation is high, the filter member covers the opening to prevent clogging. In either method, however, toner accumulates on the filter over time, causing clogging and increasing the internal pressure of the developing device, so that the toner is ejected from a gap formed in the case. No measures have been taken.
JP 2005-352076 A JP-A-6-59550

As described above, a filter is conventionally provided in order to eliminate toner ejection caused by an increase in internal pressure accompanying the operation of the developing device, but it has been difficult to eliminate clogging of the filter over time.
The present invention has been made in view of the above, and can effectively prevent clogging of a filter provided over time in order to eliminate the ejection of toner caused by an increase in internal pressure accompanying the operation of the developing device. An object of the present invention is to provide a developing device, a process cartridge, and an image forming apparatus.

In order to achieve the above object, a developing device according to a first aspect of the present invention comprises: a developer conveying screw for stirring and conveying the developer in the case; and a developing roller disposed in the opening of the case and facing the image carrier. And a clogging elimination means for oscillating the depressurization filter, wherein the vent hole provided in the case includes a depressurization filter.
The invention of claim 2 is provided with a sensor for detecting an increase in internal pressure in the case according to claim 1, and when the sensor detects that the internal pressure has reached a predetermined level or more, the clogging elimination means performs the removal. The pressure filter is vibrated.
According to a third aspect of the present invention, in the first or second aspect, the clogging eliminating means expands or contracts a filter hole when the depressurizing filter is vibrated.
According to a fourth aspect of the present invention, in the first or second aspect, when the clogging eliminating means vibrates the depressurizing filter, the depressurizing filter collides with the case to give an impact.

According to a fifth aspect of the present invention, in the first or second aspect, the clogging eliminating means generates a stick slip with the case when the depressurizing filter is vibrated.
According to a sixth aspect of the present invention, there is provided a process cartridge comprising: a photosensitive member carrying an electrostatic latent image; and a developing device for supplying toner to at least the electrostatic latent image. In the process cartridge, the developing device is the developing device according to any one of claims 1 to 5.
An image forming apparatus according to a seventh aspect of the present invention includes the process cartridge according to the sixth aspect.

In the developing device of the first aspect, the clogging of the toner is eliminated by vibrating the depressurizing filter.
According to the second aspect of the present invention, the increase in the internal pressure is detected, and when the predetermined internal pressure is detected, the clogging of the toner is resolved by vibrating the filter by the clogging eliminating means attached to the filter.
According to the third aspect of the present invention, the clogging of the toner is eliminated by installing a member for exciting the depressurizing filter opposite to the vibration direction, pulling the filter, and expanding the eyes.
In the developing device according to the fourth aspect, when the filter vibrates, an impact is given by causing it to collide with the case, and toner clogging to the filter is eliminated.

In the developing device according to the fifth aspect, a stick-slip phenomenon is generated when the filter vibrates, so that the filter is impacted and toner clogging to the filter is eliminated.
The process cartridge according to the sixth aspect can provide a process cartridge using a developing device capable of supplying a stable image quality without causing toner scattering due to toner clogging of the depressurization filter over time.
According to another aspect of the present invention, there can be provided an image forming apparatus using a developing device or a process cartridge capable of supplying a stable image quality without causing toner scattering due to toner clogging of the depressurizing filter over time.

Hereinafter, the present invention will be described in detail with reference to embodiments shown in the drawings.
FIG. 1 is a partial cross-sectional view showing a schematic configuration of an image forming apparatus including a developing device according to an embodiment of the present invention.
The electrophotographic image forming apparatus 1 includes a photosensitive drum (image carrier) 2, a charging device (not shown), an exposure device, a developing device 3, a transfer device (not shown), a cleaning device, a fixing device, and the like.
The developing device 3 is provided in the case 4 with agent conveying screws 5 and 6 for stirring and conveying the developer, the developing roller 7 disposed in the opening of the case 4 and facing the photosensitive drum 2, and the surface of the developing roller 7. A developing doctor 8 that regulates the amount of toner is provided. Further, a depressurizing filter 11 is disposed in the vent hole 10 provided in the case 4.
The chambers 4a and 4b that store the agent conveying screws 5 and 6 are partitioned by a partition plate 4c, but are connected at both ends in the longitudinal direction of the case 4 so that the developer circulates. The toner is replenished from the toner replenishing means (not shown) to the side of the chamber 4b where the toner is present and transferred to the chamber 4a.
As the developer conveying screws 5 and 6 rotate, the developer contained in the developing device case 4 is conveyed and stirred, and the developer is charged by friction. The stirred and charged developer is conveyed to the chamber 4a on the agent conveying screw (developing roller side) 5 side, and the height of the layer of the developer supplied onto the developing roller 7 is regulated by the developing doctor 8. The agent whose height is regulated by the developing doctor 8 approaches the photoreceptor 2 and is transferred to an electrostatic latent image on the photoreceptor 2. Further, the developer remaining on the developing roller 7 after development is accommodated in the developing case 4 again.

FIG. 2 is a cross-sectional view showing the main configuration of the developing device according to the first embodiment of the present invention.
The present invention is characterized in that clogging is prevented by causing the depressurization filter 11 to vibrate in a timely manner by a vibrator (clogging eliminating means) 20 such as a vibration motor.
In the developing device 3 using the two-component developer shown in FIG. 1, when the developing roller 7 is rotated, an air flow is generated by the magnetic brush formed on the developing roller 7. Along with this, the internal pressure inside the case 4 of the developing device 3 rises and a pressure difference is generated between it and the outside air. However, the pressure inside the case is reduced by the ventilation from the vent hole 10 provided with the decompression filter 11. About 30 [Pa]. However, over time, the toner flying inside the case accumulates on the depressurizing filter 11 and causes clogging.

In the present invention, when the clogging occurs regularly or when clogging occurs, the depressurization filter 11 of FIG. 2 is set to 160 to 200 [Hz] by a vibration motor (clogging eliminating means) 20 or the like such as a vibration motor or a piezoelectric vibrator. ], The toner adhering to the depressurizing filter is dropped to eliminate the clogging of the toner, and the air pressure in the case can be made equal to the initial pressure. In addition, although the example which vibrates the depressurization filter 11 in the left-right direction is shown in the figure, the vibration in the front-back direction or the up-down direction may be used.
The vibration exciter 20 is activated by a control signal from the control unit (CPU) periodically or when clogging is detected by a sensor (not shown) to vibrate the depressurization filter.
In this example, a filter holding portion 4d in which a part of the casing around the vent hole 10 is protruded in an L shape is formed to support the depressurization filter, and the vibrator 20 is disposed. It is not necessarily limited to.

Next, FIG. 3 shows a second embodiment of the present invention. The developing device 3 is characterized in that a sensor such as a pressure gauge 25 for measuring the pressure inside the case 4 is provided. When it is detected that the case internal pressure has risen beyond the allowable value, the control unit 30 that has received the detection signal operates the vibrator 20.
As described above, in the present embodiment, even if the depressurization filter 11 is clogged with time, the pressure gauge 25 detects an increase in internal pressure due to the clogging of the depressurization filter, and vibrates the depressurization filter. To eliminate clogging.

Next, FIG. 4 is a view showing a depressurizing filter and clogging eliminating means according to another embodiment of the present invention.
In this embodiment, as shown in FIG. 4 (a), vibrators (clogging eliminating means) 20 such as a vibration motor are disposed at both ends of the depressurizing filter 11, and both vibrators 20 are set to a predetermined range. By operating at the timing, the decompression filter 11 is expanded and contracted in a predetermined direction. By expanding and contracting the decompression filter 11 in the surface direction, the filter hole (filter eye) 11a constituting the decompression filter 11 is enlarged as shown by a two-dot chain line as shown in the enlarged view of FIG. Or reduced as shown by the solid line.
As described above, in the present embodiment, even if clogging occurs in the decompression filter 11 with use over time, the clogging eliminating means that vibrates the decompression filter as shown in FIG. By pulling out the pressure-reducing filter by disposing and operating the opposite ends of the filter, and expanding the filter hole 11a as shown in FIG. 4B, the clogged toner can be easily dropped, and the toner filter Remove clogging.

Instead of installing two vibration exciters, one end of the depressurization filter 11 may be fixed to the filter holding portion 4d, and the depressurization filter may be extended by the vibration exciter provided at the other end. The effect of expanding and expanding / contracting 11a can be obtained.
The pulling operation for eliminating the clogging may be performed periodically or at the time of detecting the pressure increase by the sensor shown in FIG.

  Next, FIG. 5 is a cross-sectional view of the main part showing another configuration example of the vibrator as the clogging eliminating means. In this embodiment, the depressurizing filter 11 can be advanced and retracted in the surface direction within the filter holding portion 4d. The vibration exciter 20 that vibrates the decompression filter 11 is disposed at one end of the decompression filter. When the exciter 20 is driven to vibrate the depressurization filter in the surface direction, the other end of the depressurization filter can collide with the inner wall of the filter holding portion 4d and give a strong impact to the depressurization filter. The toner can be removed to eliminate clogging.

Next, FIG. 6 is a configuration example of the clogging eliminating means according to another embodiment of the present invention, and is a modification of the configuration example of FIG.
In this embodiment, by disposing a friction resistance member 30 such as a rubber protrusion on the sliding surface of the filter holding portion 4d and the depressurizing filter 11, the depressurizing filter is pressed to the left by the vibrator 20. In this case, a stick-slip phenomenon occurs between the depressurizing filter and the filter holding portion 4d. That is, the depressurization filter is not moved smoothly in the surface direction, but is moved while causing stick slip by the frictional resistance member 30 to collide with the filter holding portion 4d, so that the impact applied to the adhered toner is further increased. The effect of eliminating clogging due to toner dropping can be enhanced.
A friction resistance member may be provided on the filter holding part side.

As described above, in the present invention, since the clogging is eliminated by vibrating the depressurization filter 11, it is possible to provide a developing device that prevents toner ejection and forms a stable image.
In addition, the sensor detects an increase in the internal pressure of the developing device due to clogging of the depressurizing filter, and at the time of detection, the depressurizing filter is vibrated by the clogging eliminating means to eliminate the clogging, thereby preventing toner ejection and stable images. A developing device to be formed can be provided.
Development that supplies a stable image that expands the eyes of the filter during vibration, eliminates clogging of the toner filter, and does not cause toner ejection by arranging vibration-exciting members opposite to the decompression filter Equipment can be provided.

In addition, when vibrating the depressurization filter using a vibrator or the like, by applying an impact by colliding with a part of the case, the clogging of the toner filter is eliminated, and no toner ejection occurs. A developing device that forms a stable image can be provided.
In addition, when vibrating the depressurization filter, by causing a stick-slip phenomenon between the case and the depressurization filter, the filter is impacted, the clogging of the filter is eliminated, and no toner ejection occurs. A developing device that forms a stable image can be provided.
Further, a process cartridge including the developing device 3 and the photoreceptor 2 of the present invention may be formed.
Further, an image forming apparatus 1 (including the process cartridge) of the present invention is combined with an image writing apparatus, a paper feeding apparatus, an image reading apparatus, and the like to construct an image forming apparatus such as a copying machine, a printer, or a facsimile. be able to.

  In Japanese Patent Laid-Open No. 5-181396, a measure similar to that of the present invention is adopted for eliminating the clogging of the filter provided in the developing device. The purpose of this prior art is to positively control the toner accumulation in the cleaning device. In particular, the present invention relates to a method for enhancing the air flow into the casing and preventing toner clogging as a result, and has a different purpose from the present invention.

1 is a partial cross-sectional view illustrating a schematic configuration of an image forming apparatus including a developing device according to an embodiment of the present invention. FIG. 2 is a cross-sectional view illustrating a configuration of a main part of the developing device according to the first embodiment of the present invention. It is a structure explanatory drawing of the developing device which concerns on the 2nd Embodiment of this invention. It is a figure which shows the depressurization filter which concerns on other embodiment of this invention, and a clogging elimination means. It is principal part sectional drawing which shows the other structural example of the vibration exciter as a clogging elimination means. It is a figure which shows the structural example of the clogging elimination means which concerns on other embodiment of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Image forming device, 2 ... Photosensitive drum, 3 ... Developing device, 4 ... Developing device case, 4a ... Chamber, 4b ... Chamber, 4c ... Partition plate, 4d ... Filter holding part, 5, 6 ... Agent conveyance screw, DESCRIPTION OF SYMBOLS 7 ... Developing roller, 8 ... Developing doctor, 10 ... Vent hole, 11 ... Depressurizing filter, 11a ... Filter hole, 20 ... Exciter, 25 ... Pressure gauge, 30 ... Control part, 30 ... Friction resistance member

Claims (7)

A developing device having a case, an agent conveying screw and a developing roller arranged in the case, and a depressurizing filter attached to a vent hole provided in the case;
A developing device comprising clogging eliminating means for vibrating the depressurizing filter.   A sensor for detecting an increase in internal pressure in the case is provided, and when the sensor detects that the internal pressure has reached a predetermined level or more, the depressurization filter is vibrated by the clogging eliminating means. 2. The developing device according to 1.   The developing device according to claim 1, wherein the clogging eliminating means expands and contracts a filter hole when the depressurizing filter is vibrated.   3. The developing device according to claim 1, wherein the clogging eliminating unit applies an impact by causing the depressurizing filter to collide with the case when the depressurizing filter is vibrated.   The developing device according to claim 1, wherein the clogging eliminating unit generates a stick slip with the case when the depressurizing filter is vibrated.   In a process cartridge in which a photosensitive member carrying an electrostatic latent image and a developing device for supplying toner to at least the electrostatic latent image are integrally formed and detachably attached to the image forming device, the developing device is claimed. Item 6. A process cartridge which is the developing device according to any one of Items 1 to 5.   An image forming apparatus comprising the process cartridge according to claim 6.

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