JPH09185237A - Developing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To separate and store such a foreign matter as paper powder included in recovered toner, also to simplify a constitution and to reduce a cost by providing a tray member on a position just under a pressure relief filter provided on the casing of a developing device. SOLUTION: The recovered toner recovered from a photoreceptor includes such the foreign matter as paper powder, and reversely electrified toner. The foreign matter is sucked by using the pressure relief filter 11 and also the sucked foreign matter is captured and held by the tray member 14 provided on the position just under the filter 11 so as to be removed from the developer. That is, when internal pressure inside the casing becomes high in the middle of the driving of the developing device 4, air goes outside from the filter 11, and such the foreign matter 13 as the paper powder suspending inside the casing is sucked as the air moves. One part of the foreign matter 13 adheres to the filter 11, and the other part freely drops inside the casing; however, since the member 14 is arranged on a foreign matter dropping path just under the filter 11, mixing of the foreign matter in normal developer can be prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a developing device in an image forming apparatus having a toner recycling mechanism for returning the residual toner removed from the surface of the photoconductor after transfer to the developing device for reuse.

[0002]

2. Description of the Related Art In an electrophotographic image forming apparatus such as a copying machine, a printer or a facsimile, a latent image on a photoconductor is developed with toner from a developing device, and the toner image is transferred and fixed on a transfer paper. However, if dust-like toner in the developing device is scattered outside the developing device, it adversely affects other units such as malfunctions, resulting in deterioration of image quality and failure. Various proposals have been made to prevent this. For example, JP-A-59-1016
In Japanese Patent Publication No. 77, by the air flow forming means, the toner dust from the doctor to the facing portion is forcibly carried into the developing casing together with the air flow, so that the dust inside the device may contaminate the equipment and the function of the optical system may be deteriorated. Proposals have been made to prevent and improve image quality. Also, JP-A-60-12
In Japanese Patent Laid-Open No. 037636, a developing device main body and a container for supplying collected toner to the developing device main body are connected by a ventilation pipe, and the developing device is allowed to perform only an aspiration operation during the developing operation. A technique has been disclosed in which toner scattering is prevented by collecting the toner powder in the container into the container. Also, a developing device is generally used in which the pressure inside the developing unit is released and the opening on the side of the developing roller is sucked into the air flow to prevent the toner powder from scattering to the outside. Further, as a method for removing impurities such as paper dust in an image forming apparatus in which residual toner on a photoconductor is removed by a cleaning device and then collected in a developing device for recycling, there is a method disclosed in JP-A-61-100783. Japanese Unexamined Patent Publication No. 62-144 discloses a technique using a cyclone separator.
Japanese Patent No. 191 discloses a technique in which a filter is provided on the toner collecting path.

[0003]

Since the collected toner contains foreign substances such as paper powder and reversely charged toner, when the collected toner is directly supplied from the developing roller 4c of the developing device onto the photosensitive member, As a means for removing foreign matter such as paper powder from a recovery toner, a cyclone separator has been used in Japanese Patent Laid-Open No. 61-100783 as a means for removing foreign matter such as paper dust from a recovery toner, but the apparatus is large and complicated. Because,
It was difficult to mount it on the image forming apparatus. Further, in JP-A-62-144191, a filter such as a mesh is arranged on the toner collecting path, but the mesh is apt to be clogged, and if maintenance is not performed frequently, it will be blocked and the machine will be damaged. I was afraid to do it. Further, there is a developing device in which a filter for releasing the pressure in the developing unit is provided in a proper place in order to prevent the toner from scattering, but it is used only for the pressure release, and it is not so effective. The present invention has been made in view of the above, and by using a depressurizing filter, separating foreign matter such as paper powder contained in the recovery toner, and storing the separated foreign matter. The purpose of the present invention is to simplify the structure, reduce the cost, enhance the detachability with the developing unit, facilitate the maintenance, and prevent the foreign matter once stored from leaking to the outside of the unit.

[0004]

In order to achieve the above object,
According to a first aspect of the present invention, in an image forming apparatus that recycles a recovery toner collected by a cleaning device to a developing device, a tray is provided directly below a pressure releasing filter provided in a casing of the developing device for releasing pressure. It is characterized by comprising a member. According to a second aspect of the present invention, in the developing device according to the first aspect, a guide member is provided, which stands up the peripheral portion of the tray member. According to a third aspect of the present invention, in the developing device according to the first aspect, the tray member is integrated with a filter casing that supports the filter, and these integral structures are detachably attached to the developing device. It is characterized by being. Claim 4
In the developing device according to the first aspect of the invention, a valve is provided in the ventilation part between the tray member and the filter.

[0005]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to embodiments shown in the drawings. FIG. 1 is a configuration diagram of an image forming unit of an image forming apparatus provided with a mechanism for recycling a recovery toner as an embodiment of the present invention, and FIG. 2 is a diagram showing details of the A portion of FIG. In FIG. 1, reference numeral 1 is a photoconductor drum as an image carrier, 2 is an optical device for writing optical image information such as reflected light of an original, 3 is an eraser for erasing a latent image as necessary, 4 is a latent image. A developing device for supplying and developing toner, 5 is a pre-transfer charge eliminating device, 6 is a transfer device for transferring the toner image on the photoconductor onto the transfer paper P, and 7 is cleaning for removing toner and the like remaining on the photoconductor. A device, 8 is a static eliminator for removing residual charges, 9 is a charging device for uniformly charging the photoconductor prior to image formation, 10 is a collected toner conveying device, 11 is a hole 4b in a proper position of the casing 4a of the developing device. The pressure relief filter is arranged. Cleaning device 7
The toner collected from the surface of the photoconductor 1 by the blade 7a is collected in the developing device by the collected toner conveying device 10 and is recycled. Since the collected toner contains foreign matter such as paper powder and reversely charged toner, if the collected toner is directly supplied onto the photoconductor from the developing roller 4c of the developing device, problems such as deterioration of image quality are caused.

The characteristic construction of the present invention is that the depressurizing filter 11 is used to adsorb the foreign matter, and the adsorbed foreign matter is captured and held by the tray member 14 provided immediately below the filter to allow the foreign matter to be developed. The point is that it was removed from. The filter 11 is attached to the hole 4b through the filter casing 12, and operates as follows. That is, as shown in the driving state diagram of FIG.
When the internal pressure in the casing 4a increases during the driving of the air, the air escapes from the depressurization filter 11 to the outside as shown by the arrow, and the paper dust or the like 13 (others) floating in the casing along with the movement of the air (others) Foreign matter (including a floating toner that is reversely charged) is sucked by the pressure release filter 11. Fig. 2 (b)
Is a diagram showing a state in which the driving is stopped, and the foreign matter 13 such as paper dust and reversely charged floating toner adsorbed on the pressure release filter 11 is partially attached to the pressure release filter 11, but the others are indicated by arrows. As shown in FIG. 3, it falls freely into the casing and is mixed with the existing developer (not shown) in the casing. Therefore, if left as it is, the developer containing the foreign matter is applied to the photoconductor 1 from the developing roller 4c, which causes various problems such as deterioration of image quality. The configuration shown here is similar to that of the conventional example, but in the present invention, the filter 11 is used as described above.
Since the tray member 14 is arranged in the foreign matter falling path immediately below the above, the situation in which the foreign matter is mixed into the existing normal developer is prevented.

That is, FIGS. 3 (a), 3 (b) and 3 (c) are operation explanatory views of one embodiment of the present invention, in which the depressurizing filter 11 is used.
By providing the tray member 14 at a position directly below, the paper dust or the like 1 once sucked in the direction of the arrow when the developing device is driven.
3 and the like fall onto the tray member 14 when the driving is stopped and can be separated without mixing with the developer. As shown in FIG. 3 (b), the paper powder 13 etc. dropped and accumulated on the tray member 14 may be spilled from the tray member 14 or may be blown up by the air current as shown in FIG. 3 (c). It will fall on top. 4 (a), (b) and (c) are diagrams for explaining the configuration and operation of another modified example, in which two standing edge portions of the tray member 14 are provided with standing portions for preventing fall over the entire circumference. A (guide portion) 14a is provided upright, and a thin film-shaped valve 15 extends upward from two opposite edge portions. When the developing device is not driven, the valve 15
Is in a state of standing almost vertically as shown in FIG. 4 (b),
When the developing device is driven to generate an air flow that escapes from the filter 11 to the outside as shown by the arrow in FIG. 4, the valve 15 bends inward as shown in the figure, and the paper dust 13 placed on the air flow from the gap outside the valve 13
Are adsorbed on the lower surface of the filter 11. When the driving of the developing device is stopped, the valve 15 returns to its original shape as shown in (b) to cut off the retreat path of the paper dust 13 so that the paper dust 13 once adsorbed by the filter.
Etc. can be stored in the tray member 14 without leaking. Even if the valve 15 is not provided and only the upright portion 14a is provided, the foreign matter capturing property and the retaining property are improved as compared with the case of the embodiment of FIG. FIG. 5 is a perspective sectional view showing the configuration of a modified example of the form example of FIG. 4, and in this form example, the casing 12 is used.
And the tray member 14 are integrated, and the filter 11 is assembled by sticking the seal 11A on the casing 12. At the time of maintenance, the paper dust 13 and the like can be removed only by replacing the assembled parts.

[0008]

According to the first aspect of the present invention, since the tray-shaped member is provided below the depressurizing filter, foreign matter such as paper dust adsorbed on the lower surface of the filter when the developing device is driven is the tray member when the driving is stopped. Since it drops and is held on the upper side, mixing with the developer in the developing device is prevented, and the developer can be separated. According to the second aspect of the present invention, since the guide portion for holding the paper dust or the like once caught is provided around the tray member, the separated paper dust or the like can be reliably stored. Claim 3
According to the invention, since the tray member is integrally formed with the pressure relief filter casing and is detachable from the developing device, the maintenance is easy. In the invention of claim 4,
Since a valve is provided in the ventilation section between the pressure release filter and the pan member, it not only prevents backflow of the paper powder etc. once separated on the pan member, but also easily leaks the paper powder etc. during maintenance. It will be exchangeable.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a main part configuration of an example of an image forming apparatus to which a developing device of the present invention is applied.

2A and 2B are views for explaining a defect of a pressure relief filter.

3 (a), (b) and (c) are explanatory views of the structure and operation of a pressure relief filter according to an embodiment of the present invention.

4 (a), (b) and (c) are explanatory views of the structure and operation of a pressure relief filter according to another embodiment of the present invention.

5 is a perspective sectional view showing a configuration of a modified example of FIG.

[Explanation of symbols]

1 ... Photoreceptor, 2 ... Optical device, 3 ... Eraser, 4 ...
・ Developing device, 5 ... Pre-transfer charge eliminating device, 6 ... Transfer device,
7 ... Cleaning device, 8 ... Static eliminator, 9 ... Charging device, 10 ... Collection toner-conveyance path, 11 ... Pressure release filter, 11A ... Filter seal, 12. ..Pressure release filter casing, 13 ... Paper dust (including foreign matter and reversely charged floating toner). 14 ... saucer member, 14a ...
Guide part, 15 ... valve,

Claims (4)

[Claims] 1. An image forming apparatus for recycling collected toner collected by a cleaning device to a developing device, wherein a tray member is provided directly below a pressure releasing filter provided in a casing of the developing device for releasing pressure. A developing device comprising: 2. The developing device according to claim 1, further comprising a guide member that raises a peripheral portion of the tray member. 3. The developing device according to claim 1, wherein:
The developing device, wherein the tray member is integrated with a filter casing that supports the filter, and these integrated structures are detachably attached to the developing device. 4. The developing device according to claim 1, wherein:
A developing device, wherein a valve made of an elastic material is provided in a ventilation part between the tray member and the filter.