JP2000293033A - Developing device, process cartridge and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent much developer from scattering even in the case of giving a shock caused by dropping or the like, by arranging a developer blowout preventing roller between a developer carrying roller and a developing device. SOLUTION: A developing roller 9c functioning as a developer carrying roller is arranged at an aperture part of a developing container 23 in which a toner as the developer is stored, and a blowout preventing roller 24 functioning as a developer blowout preventing roller is arranged between the roller 9c and the container 23. The roller 9c is a cylinder consisting of hard material and is driven to be rotated in a direction shown by an arrow A, and the roller 24 is the cylinder consisting of an elastic member such as urethane foam or sponge and is pressed to the roller 9c with fixed pressure. Furthermore, the roller 24 comes in contact with a bottom part constituting the aperture part of the container 23. However, force to press the roller 24 to the roller 9c is strong, consequently, frictional force is also strong, so that the roller 24 is rotated in the direction shown by an arrow B at surface speed nearly the same as the surface speed of the roller 9c.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a developing device, a process cartridge, and an image forming apparatus.

Here, examples of the image forming apparatus include an electrophotographic copying machine, an electrophotographic printer (for example, an LED printer, a laser beam printer, etc.), an electrophotographic facsimile machine, an electrophotographic word processor, and the like.

A process cartridge is a cartridge in which at least one of a process unit such as a charging unit, a developing unit, and a cleaning unit, and an electrophotographic photosensitive member are integrally formed as a cartridge so as to be detachable from an image forming apparatus main body. In the present invention, the electrophotographic photosensitive member and at least the developing means as the process means are integrally formed into a cartridge.

[0004]

2. Description of the Related Art Conventionally, in an electrophotographic image forming apparatus using an electrophotographic image forming process, a cartridge is integrally formed with an electrophotographic photosensitive member and process means acting on the electrophotographic photosensitive member, and this cartridge is mounted in an image forming apparatus. A process cartridge system that can be directly attached to and detached from the main body is employed.

According to this process cartridge, maintenance of the apparatus can be performed by the user himself without relying on a service person, so that operability can be remarkably improved. Therefore, this process cartridge system is widely used in image forming apparatuses.

[0006]

The process cartridge described above has an image forming apparatus in which toner is moved from a toner container to a developing container by a process such as pulling out a toner seal in advance to form a surface image. It is loaded into the body.

After that, by driving the main body of the image forming apparatus, the stirring member of the process cartridge is operated, and the toner (developer) is moved by the weight of the toner itself.
It reaches the developing roller (developer carrying roller).

Here, in the process cartridge,
The developing roller is close to the photosensitive drum (image carrier),
The photosensitive drum has an opening outside for convenience in contact with the paper (recording medium).

The developing container also has an opening for the purpose of driving the developing roller to rotate. For this reason, when the process cartridge is removed from the image forming apparatus main body and dropped by mistake, a large amount of toner is scattered from the opening.

Also, a color LBP (laser printer)
In such a case, the toner container is often constituted by a single toner container. In this case as well, a large amount of toner is scattered by dropping or hitting when the developing device is replaced.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems, and an object of the present invention is to provide a developing device, a process cartridge, and an image forming apparatus in which developer is less scattered.

[0012]

According to one aspect of the present invention, there is provided a developing device detachable from an image forming apparatus main body, comprising: a developing container for storing a developer;
A developer carrying roller disposed at an opening of the developing container,
And a developer ejection preventing roller disposed between the developer carrying roller and the developing container.

When a strong impact or the like is given when the developer is dropped, the developer scattered from the developing container is limited to the developer attached to a portion of the developer carrying roller facing the electrophotographic photosensitive member.
Moreover, since the developer is attracted to the developer carrying roller by magnetic force or electrostatic force as described above,
The amount of scattering is small, and the amount present is small due to the thin layer. That is, since a spout prevention roller is disposed in the gap between the developer carrying roller and the developing container, which has been the conventional scattering path of the developer inside the developing container having the largest amount of the developer, the developer passes through this portion. As a result, the developer does not scatter.

The invention according to claim 2 is characterized in that the surfaces of the developer ejection preventing roller and the developer carrying roller facing each other rotate in the same direction.

If the opposing surfaces of the developer ejection prevention roller and the developer carrying roller are rotated in the same direction, image formation by the developer carrying roller is not hindered. Further, there is also an effect of scooping up the developer spilling down the surface of the developer carrying roller and returning the developer to the developing container.

The invention according to claim 3 is characterized in that the developer ejection preventing roller is made of an elastic member, and is in contact with each of the developer carrying roller and the developing container.

Since the developer is pressed against both the developing roller and the developing container, the scattering of the developing agent from the gap between the developing roller and the developing container is reliably blocked. Also,
Since it is constituted by an elastic member, there is no possibility of damaging the developer carrying roller.

According to a fourth aspect of the present invention, in the developing container,
One end is fixed to the developing container, and the other end is in contact with the developer ejection preventing roller, and a developer regulating member is provided to regulate the developer from entering a portion where the developer ejection preventing roller contacts the developing container. It is characterized by.

Since the developer ejection preventing roller is rotated between the developing container and the developing container in a direction of discharging the developing agent to the outside of the developing container, a portion which is close to or pressed against the developing container by the developer regulating member. To prevent the developer from leaking, and to surely prevent the developer from leaking.

The invention according to claim 5 is characterized in that the developer ejection preventing roller has a magnetic force on its surface, and maintains a constant distance between the developer carrying roller and the developing container. .

With this configuration, it is possible to prevent the developer from being scattered through the gap between the ejection roller, the developer carrying roller, and the developing container due to the magnetic force. Also,
Since the developer ejection preventing roller is not in contact with the developer carrying roller, the developer can be sealed in the developing container without damaging the developer carrying roller.

According to a sixth aspect of the present invention, in the fifth aspect, a developer scraping member for scraping off the developer attached to the developer ejection roller is provided inside the developing container.

The developer adhered to the developer ejection preventing roller by the magnetic force can be scraped off by the developer scraping member.

According to a seventh aspect of the present invention, an electrophotographic photosensitive member and at least the developing device according to any one of the first to sixth aspects as a process means are integrally formed into a cartridge, and the cartridge is provided to the image forming apparatus main body. The process cartridge is characterized in that it is detachable.

According to the process cartridge of the present invention,
Since it is possible to prevent a large amount of developer from being scattered due to an impact at the time of dropping, the handling property is further improved.

The invention according to claim 8 is an electrophotographic photosensitive member on which an electrostatic latent image is formed, and any one of claims 1 to 6 for developing the electrostatic latent image formed on the electrophotographic photosensitive member. An image forming apparatus comprising: the developing device according to any one of the above items.

According to the image forming apparatus of the present invention, a large amount of the developer can be prevented from being scattered by an impact at the time of dropping or the like, so that the inside of the image forming apparatus can be kept clean.

[0028]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the illustrated embodiments.

First Embodiment FIGS. 1 to 7 show an image forming apparatus and a process cartridge according to a first embodiment of the present invention.

First, an electrophotographic image forming apparatus to which a developing device and a process cartridge according to the present invention can be mounted will be described with reference to FIGS.

[Schematic Configuration of Image Forming Apparatus and Process Cartridge] As shown in FIGS. 2 and 3, this image forming apparatus includes a photosensitive drum 7 as an electrophotographic photosensitive member on which an electrostatic latent image is formed. A developing device 9 for developing the electrostatic latent image formed on the photosensitive drum 7.
The photosensitive drum 7 and the developing device 9 are integrally formed as a process cartridge B as a cartridge, and are configured to be detachable from the image forming apparatus main body A.

The image forming apparatus main body A scans light from a laser light source that emits light in accordance with image information with a rotating polygon mirror 1a, and also scans a lens 1b and a reflection mirror 1a.
c for irradiating through the optical means 1
Irradiates a light image based on image information from the photosensitive drum 7
A latent image is formed on the toner image, and the latent image is visualized with a toner as a developer by a developing device 9 to form a toner image.

In synchronism with the formation of the toner image, the recording medium 2 is reversely conveyed from the paper feed cassette 3a by conveying means 3 including a pickup roller 3b, a pair of conveying rollers 3c and 3d, a pair of registration rollers 3e, and the like. Cartridge B
In the image forming unit formed as a cartridge, the toner image formed on the photosensitive drum 7 is transferred to the recording medium 2 by applying a voltage to the transfer roller 4 as a transfer unit.

Further, a fixing roller 5b having a heater 5a built therein while guiding the recording medium 2 after the transfer of the toner image with a guide member 3f, and a driving roller 5c for pressing the recording medium 2 to the fixing roller 5b to convey it. Transport to 5,
The transfer toner image is fixed on the recording medium 2. Then, the recording medium 2 is conveyed by a pair of discharge rollers 3g, 3h, and 3i, and is discharged to a discharge unit 6 through a reversing path 3j. In addition, regarding the discharge, the swingable flapper 3k can be operated, and the discharge can be directly performed by the discharge roller pair 3m without passing through the reverse conveyance path 3j.

On the other hand, as shown in FIGS. 4 and 5, the process cartridge B constituting the image forming section rotates the photosensitive drum 7 having the photosensitive layer, and transfers the photosensitive drum 7 to the charging roller 8 serving as a charging means. Charged uniformly by applying voltage,
The light image from the optical unit 1 is exposed to the photosensitive drum 7 via an exposure unit to form a latent image, and the latent image is developed by the developing device 9.

The developing device 9 sends out the toner in the toner storing portion 9a by a toner sending member 9b, rotates a developing roller 9c as a developer carrying roller having a fixed magnet therein, and applies a triboelectric charge by a developing blade 9d. The formed toner layer is formed on the surface of the developing roller 9c, and the toner is transferred to the photosensitive drum 7 in accordance with the electrostatic latent image, thereby forming a toner image and visualizing the toner image.

After the toner image is transferred to the recording medium 2 by applying a voltage having a polarity opposite to that of the toner image to the transfer roller 4, the toner remaining on the photosensitive drum 7 is scraped off by the cleaning blade 10a, and the toner is discarded. The cleaning unit 10 that collects the toner in the toner reservoir 10b removes the residual toner on the photosensitive drum 7, and prepares for the next step.

Each component such as the photosensitive drum 7 is housed in a housing composed of a developing frame 12 in which a toner container 11 and a developing container 23 are connected and a cleaning frame 13 to form a cartridge. The cartridge B is detachably mounted on a cartridge mounting means provided in the apparatus main assembly A.

When the opening / closing member 15 is opened, a cartridge mounting space is provided as shown in FIGS. 6 and 7, and the cartridge mounting member 16 is mounted on the left and right inner side surfaces of the main body A of the image forming apparatus. The left and right cartridge mounting members 16 are provided with guide portions 16a for inserting the process cartridges B facing each other. The process cartridge B is inserted along the guide portion 16a, and the opening / closing member 15 is closed to mount the process cartridge B on the image forming apparatus main body A.

Next, the structure of the process cartridge housing will be described in more detail with reference to FIGS.

[Structure of Process Cartridge Housing] The process cartridge B according to the present embodiment has a housing formed by combining the developing frame 12 and the cleaning frame 13, and the structure will be described.

As shown in FIG. 4, the developing frame 12 comprises a toner container 11 and a developing container 23. Toner container 1
1, a toner storage portion 9a is formed, and a toner feeding member 9b is attached to the toner storage portion 9a.

A developing roller 9c and a developing blade 9d are mounted on the developing container 23, and a stirring member 9e for circulating toner in the developing chamber is rotatably mounted near the developing roller 9c. Then, the toner container 11 and the developing container 23 are welded to form an integral developing frame 12.

Each member of the photosensitive drum 7, the charging roller 8 and the cleaning means 10 is attached to the cleaning frame 13, and further covers the photosensitive drum 7 when the process cartridge B is removed from the image forming apparatus main body A. A drum shutter member 18 that protects the drum shutter member is attached to form a cleaning unit. Then, the process cartridge B is configured by connecting the developing unit and the cleaning unit.

For this purpose, a cover member (not shown) for rotatably supporting both ends of the developing roller 9c is attached to both longitudinal sides of the developing frame 12, and a tip of an arm 19 formed on the cover member. 8 and 9 are provided with a rotating shaft 20 (FIGS. 8 and 9 show only one side).

On the other hand, concave portions 21 for positioning and locking the rotation shaft 20 are provided at two positions on both sides in the longitudinal direction of the cleaning frame 13. The developing unit and the cleaning unit are rotatably connected around the rotation shaft 20 by inserting the rotating shaft 20 into the concave portion 21 and screwing the connecting member 22 having the convex portion 22 a to the cleaning frame 13. Then, the developing roller 9c is pressed against the photosensitive drum 7 by the weight of the developing unit.

At this time, the developing roller 9c is securely pressed against the photosensitive drum 7 by urging the developing frame 12 downward by the compression spring 22b attached to the connecting member 22.

Accordingly, by attaching spacer rings (not shown) to both ends in the longitudinal direction of the developing roller 9c, this ring is pressed against the photosensitive drum 7, and the photosensitive drum 7 and the developing roller 9c face each other at a constant interval. I do.

Next, the developing device 4 of the process cartridge according to the present invention will be described in more detail.

As shown in FIG. 1, a developing container 23 containing a toner as a developer, a developing roller 9c as a developer carrying roller disposed at an opening of the developing container 23,
An ejection roller 24 as a developer ejection prevention roller disposed between the developing roller 9c and the developing container 23;
It has.

The developing roller 9c is a cylinder made of a hard material such as aluminum and is driven to rotate in the direction of arrow A.

The blowout prevention roller 24 is a cylinder made of an elastic member such as urethane foam or sponge, and is pressed against the developing roller 9c with a constant pressure. Further, the blowout prevention roller 24 is also in contact with the bottom constituting the opening of the developing container 23, but the force pressed against the developing roller 9c is larger, and as a result, the frictional force is larger. It rotates in the direction of arrow B at a surface speed of approximately the same speed.

A case where the process cartridge B alone is dropped in such a configuration will be described. FIG.
The toner is attracted to the surface of the developing roller 9c by the magnetic force of the built-in magnet 25 or the electrostatic force of the surface. The developing roller 9c is rotating in the direction of arrow A, and a developing blade 9d made of an elastic member such as rubber is pressed against the surface thereof at a constant pressure.

For this reason, the amount of toner on the developing roller 9c is regulated by the developing blade 9d, and the toner is in a thin layer at the position of the developing roller 9c facing the photosensitive drum 7.

In this state, when the process cartridge B is dropped and a strong impact is applied, the toner scattered from the developing container 23 is limited to the toner adhered to the portion of the developing roller 9c facing the photosensitive drum 7, Moreover, since the toner is attracted to the developing roller 9c by the magnetic force or the electrostatic force as described above, the scattering amount is small,
Since it is a thin layer, its abundance is inherently small.

That is, in the gap between the developing container 9 and the developing container 9 below the developing roller 9c, which is the conventional scattering path of the toner inside the developing container 23 having the largest amount of toner, an ejection prevention roller 24 is provided. The toner is not scattered through this portion because it is pressed against both the developing container 23 and the developing container 23.

The blowout prevention roller 24 is a developing roller 9c.
Can be installed at a position distant from the photosensitive drum 7 and the developing blade 9c to such an extent that image formation is not hindered. Further, the toner is stored in the developing container 23 without damaging the developing roller 9c due to the elastic member. Can be sealed.

Further, since the ejection prevention roller 24 is rotated in the direction of discharging the toner to the outside of the developing container 23 between the developing container 23 and the developing container 23, it is pushed against the developing container 23 by the toner regulating plate 25 shown in FIG. It is desirable that the toner does not come into contact with the applied portion.

Further, in the present embodiment, the blowout prevention roller 24 is driven by the printing force from the developing roller 9c. However, it can be more positively driven to rotate from the outside by a mechanism such as a gear or a belt. In this case, it is desirable to provide a clutch in the drive transmission path so that driving by surface friction is dominant as in the present embodiment.

Further, as another effect of the present invention, the toner that spills along the surface of the developing roller 9c can be scooped up by the ejection prevention roller 24 and returned into the developing container 23.

[Second Embodiment] Next, a second embodiment of the present invention will be described with reference to FIG.

The difference between the developing frame shown in FIG. 10 and the developing frame of the first embodiment is that the blowout prevention roller 24 is not an elastic member. <A roller having a magnetic force on its surface. Roller 24 and developing roller 9c
And that the toner is prevented from being scattered between the developing containers 23.

That is, the blowout prevention roller 24 shown in FIG. 10 is a cylindrical plastic magnet, both ends of which are rotatably supported by the developing container 23, and is rotated in the direction of arrow B by a driving means (not shown). .

The blowout prevention roller 24 and the developing roller 9c
There is a small gap between the developing container 23 and the size of the gap, which is determined by the magnetic force of the surface of the ejection prevention roller 24 and the properties of the toner, so that the toner does not leak even when an impact such as a drop is applied. It is usually 1 mm or less.

As in the first embodiment, a spouting prevention roller 24 is provided between the developing container 9 and the developing container 9 under the developing roller 9c, which is the conventional scattering path of the toner inside the developing container 23 having the largest amount of toner. Since the toner is present and the gap between the developing roller 9c and the developing chamber 23 is sealed with magnetic force, the toner does not scatter through this part.

The blowout prevention roller 24 is connected to the developing roller 9c.
Can be installed at a position away from the drum and the developing blade so as not to hinder image formation.
c, the toner can be sealed in the developing container 23 without damaging the developing roller 9c.

Since toner adheres to the ejection prevention roller 24 by magnetic force, it is desirable that the toner is scraped off immediately before the portion exposed from the developing container 23 by the toner scraping member 26 shown in FIG.

Further, as another effect of the present invention, the toner that spills along the surface of the developing roller 9c can be scooped up by the blowout prevention roller 24 and returned into the developing container 23.

In each of the above embodiments, an example has been described in which the developing device 9 is incorporated in the process cartridge B. However, the developing device 9 may be made into a cartridge and detachable from the image forming apparatus main body A. It is. The process cartridge B includes a charging roller 8 as a charging unit, a developing device 9 and a cleaning unit 10.
And the photosensitive drum 7 are integrally formed as a cartridge. The process cartridge includes the photosensitive drum 7 and
It has at least one of the process means.

Therefore, as a mode of the process cartridge of the present invention, in addition to the above-described embodiment, for example, the photosensitive drum 7 and the developing device 9, the photosensitive drum 7 and the developing device 9, the charging roller 8, the photosensitive roller 8, Drum 7 and developing device 9
The cleaning unit 10 may be integrally formed as a cartridge so as to be detachable from the image forming apparatus main body A. The process cartridge B can be attached to and detached from the image forming apparatus main body A by the user. Thus, the maintenance of the image forming apparatus main body A can be performed by the user himself.

[0071]

As is apparent from the above description, according to the first aspect of the present invention, the developer carrying roller which is the conventional scattering path of the developer inside the developing container having the largest amount of the developer is provided. A spout prevention roller is disposed in the gap between the developer and the developing container, so that a large amount of the developer can be prevented from being scattered even when an impact is applied due to a factor such as dropping.

According to the second aspect of the present invention, the opposing surfaces of the developer ejection prevention roller and the developer carrying roller are rotated in the same direction, so that image formation by the developer carrying roller is not hindered. Further, there is also an effect of scooping up the developer spilling down the surface of the developer carrying roller and returning the developer to the developing container.

According to the third aspect of the present invention, since the developer ejection prevention roller is pressed against both the developer carrying roller and the developing container, the developer is prevented from developing from the gap between the developer carrying roller and the developing container. Dispersion of the agent is reliably blocked. In addition, since it is constituted by the elastic member, there is no possibility of damaging the developer carrying roller.

According to the fourth aspect of the present invention, the developer is regulated by the developer regulating member so that the developer does not come into contact with or pressed against the developing container.
The leakage of the developer is reliably prevented.

According to the invention of claim 5, it is possible to prevent the developer from being scattered through the gap between the ejection roller, the developer carrying roller, and the developing container due to the magnetic force. Further, since the developer ejection preventing roller is not in contact with the developer carrying roller, the developer can be sealed in the developing container without damaging the developer carrying roller.

According to the invention of claim 6, the developer adhered to the developer ejection preventing roller by the magnetic force can be scraped off by the developer scraping member.

According to the process cartridge of the present invention, it is possible to prevent a large amount of developer from being scattered by an impact at the time of dropping or the like, so that the handleability is further improved.

According to the image forming apparatus of the present invention, a large amount of the developer can be prevented from being scattered by an impact at the time of dropping or the like, so that the inside of the image forming apparatus can be kept clean.

[Brief description of the drawings]

FIG. 1 is a sectional view of a process cartridge according to Embodiment 1 of the present invention.

FIG. 2 is an overall configuration diagram of an electrophotographic image forming apparatus to which the process cartridge according to Embodiment 1 of the present invention is mounted.

FIG. 3 is a perspective view of the image forming apparatus of FIG. 2 as viewed from the outside.

FIG. 4 is a configuration diagram illustrating a process cartridge mounted on the image forming apparatus of FIG. 2;

FIG. 5 is a perspective view of the process cartridge of FIG. 4 as viewed from the outside.

FIG. 6 is a perspective view showing a mounting portion of the image forming apparatus main body on which the process cartridge of FIG. 4 is mounted.

FIG. 7 is a perspective view of a mounting portion of the image forming apparatus main body on which the process cartridge of FIG. 4 is mounted, as viewed from a direction different from FIG.

FIG. 8 is an explanatory view showing a mounting member of the process cartridge of FIG. 4;

FIG. 9 is a sectional view showing the mounting member of FIG. 8;

FIG. 10 is a sectional view of a developing frame according to a second embodiment of the present invention.

[Explanation of symbols]

 A: Image forming apparatus B: Process cartridge 1: Optical means 4: Transfer means 7: Photoconductor drum (electrophotographic photoconductor) 8: Charging means 9: Developing device 9c: Developing roller 10: Cleaning means 11: Toner container 12: Developing frame 23 Developing container 24 Spray prevention roller 25 Toner regulating plate 26 Toner scraping member

Claims (8)

[Claims] 1. A developing device detachable from a main body of an image forming apparatus, comprising: a developing container for storing a developer; a developer carrying roller disposed at an opening of the developing container; And a developer ejection preventing roller disposed between the container and the container. 2. The developing device according to claim 1, wherein the opposed surfaces of the developer ejection preventing roller and the developer carrying roller rotate in the same direction. 3. The developing device according to claim 1, wherein the developer ejection preventing roller is made of an elastic member, and is in contact with each of the developer carrying roller and the developing container. 4. An inside of the developing container, one end of which is fixed to the developing container and the other end of which abuts on a developer discharging preventing roller, thereby restricting the developer from flowing into a portion where the developing agent discharging preventing roller comes into contact with the developing container. The developing device according to claim 3, further comprising a toner regulating member that performs the operation. 5. The developing device according to claim 1, wherein the developer ejection preventing roller has a magnetic force on a surface thereof, and maintains a constant distance between the developer carrying roller and the developing container. 6. The developing apparatus according to claim 5, wherein a developer scraping member for scraping off the developer attached to the developer ejection roller is provided inside the developing container. 7. An electrophotographic photosensitive member and at least a developing device according to claim 1 as a process means are integrally formed as a cartridge, and are detachably mountable to an image forming apparatus main body. A process cartridge. 8. An electrophotographic photosensitive member on which an electrostatic latent image is formed,
A developing device according to any one of claims 1 to 6, for developing an electrostatic latent image formed on the electrophotographic photosensitive member,
An image forming apparatus comprising: