JP2023013157A - developing device - Google Patents

Abstract

To prevent toner from being scattered by an air flow from an opening formed between a developer carrier and a seal member in a non-carrying area of the developer carrier.SOLUTION: A developing device comprises: a developing sleeve 24 that has a carrying area 24a being an area having a developer conveyance ability and a non-carrying area 24b being an area not having the developer conveyance ability, and carries a developer in the carrying area 24a to convey the developer; a regulation blade that regulates an amount of the developer carried in the carrying area 24a; an opposite member 27 that is arranged opposite to the developing sleeve 24 on the downstream of the regulation blade and on the upstream of a developing position with respect to a rotation direction R3 of the developing sleeve 24; a flexible seal member 28 that is provided opposite to the carrying area 24a and the non-carrying area 24b so as to be in contact with the developer carried in the carrying area 24a; and sealing members 29 that are provided on the seal member 28 so as to be sandwiched between the seal member 28 and the non-carrying area 24b.SELECTED DRAWING: Figure 3

Description

The present invention relates to a developing device applied to an image forming apparatus using an electrophotographic method or an electrostatic recording method.

An image forming apparatus using an electrophotographic method or an electrostatic recording method normally uses a developer composed of a toner and a magnetic carrier. In the developing device, after the developer is carried on a developer carrying member having a magnet, the amount of developer is regulated to a desired amount by a regulating member for regulating the carrying thickness of the developer, and the developer carrying member rotates. is conveyed to an image forming area where the image carrier and the developer carrier face each other. In such a developing device, while the developer is conveyed from the regulating member to the image forming area, the toner may be separated from the carrier due to the rotational motion of the developer carrier, and the toner may scatter outside the developing device such as the charging device. There is Therefore, in order to prevent the scattering of toner, a configuration is employed in which the area from the regulating member to the image forming area is covered with a facing member arranged to face the developer carrying member. Further, a flexible sheet-like sealing member is often attached to the facing member. The seal member is made of urethane rubber or the like, and often has a structure in which the tip is brought into contact with the developer on the developer carrier or the image carrier.

However, in the conventional developing device, the airflow generated by the rotational motion of the developer carrier is suppressed by the seal member from flowing in the rotational direction, so that the airflow flows into the openings at both ends of the developer carrier in the rotation axis direction. There was a time when I was lost. There is a problem that the toner may be scattered outside the developing device by the airflow flowing to the openings at both ends in the rotation axis direction. In order to solve this problem, in a developing device provided with a first sealing member whose leading end is brought into contact with the developer on the developer carrier and a second sealing member whose leading end is brought into contact with the image carrier, two seals are provided. A configuration has been proposed in which sealing members are provided at both ends between the sealing members (see Patent Document 1). In this developing device, the airflow generated by the rotational movement of the developer carrying member flows into the openings at both ends in the rotation axis direction between the first seal member and the second seal member, and the toner carried by the airflow develops. He is trying to suppress scattering to the outside of the device.

Japanese Patent Application Laid-Open No. 2006-221132

However, in the developing device disclosed in Patent Document 1, when the developer carrying member carries the developer, the developer lifts the seal member. At this time, in the non-carrying regions where the developer is not carried at both ends in the rotation axis direction, a gap is generated between the developer carrying member and the seal member to form an opening. Therefore, the air flow generated by the rotational motion of the developer carrying member flows into the opening formed in the non-carrying area, and the toner separated from the carrier is scattered from the opening of the non-carrying area by the air current. There is fear. There is a problem that the scattered toner accumulates in the sealing members provided at both ends in the direction of the rotation axis, and the accumulated toner may drop, resulting in staining of the image.

An object of the present invention is to provide a developing device capable of suppressing scattering of toner by an air current from an opening formed between a developer carrier and a seal member in a non-carrying region of the developer carrier. aim.

The developing device of the present invention includes a developing container containing a developer containing toner and carrier, and a rotatable developer carrying and conveying the developer toward a developing position where an electrostatic image formed on an image carrier is developed. A developer carrying member comprising a carrying area which is an area where the developer carrying ability of the developer carrying member exists and a non-carrying area which is an area where the developer carrying ability of the developer carrying member does not have the developer carrying ability. a regulating portion for regulating the amount of developer carried on the carrying area; and a developer carrying member downstream of the regulating portion and upstream of the developing position with respect to the rotational direction of the developer carrying member. a facing portion arranged to face the body; a flexible sealing portion provided facing the carrying region and the non-carrying region so as to come into contact with the developer carried on the carrying region; and a sealing member provided in the seal portion so as to be sandwiched between the seal portion and the non-carrying region.

According to the present invention, it is possible to suppress scattering of toner by an air current from the opening formed between the developer carrier and the seal member in the non-carrying region of the developer carrier.

1 is a schematic cross-sectional view of an image forming apparatus according to a first embodiment; FIG. 2 is a cross-sectional view of the developing device according to the first embodiment; FIG. 1 is a front view of a developing device according to a first embodiment; FIG. FIG. 5 is a cross-sectional view of a developing device according to a modification of the first embodiment; 8 is a cross-sectional view of a developing device according to a second embodiment; FIG. FIG. 3 is a cross-sectional view showing part of a conventional developing device; 7A is a front view of the developing device viewed from a first direction D1 in FIG. 6, and FIG. 7B is a rear view of the developing device viewed from a second direction D2 in FIG.

<First Embodiment>
A first embodiment of the present invention will be described in detail below with reference to FIGS. 1 to 4. FIG. First, a schematic configuration of the image forming apparatus 1 of this embodiment will be described with reference to FIG. In this embodiment, the image forming apparatus 1 employs an electrophotographic system, in which charged toner is supplied from a developing device to an electrostatic latent image formed on an image carrier to visualize the image, and then the image is visualized. The resulting toner image is transferred to paper, and heat and pressure are applied to fix the toner image on the paper, producing a permanent image.

[Image forming apparatus]
FIG. 1 is a schematic diagram showing the configuration of an image forming apparatus 1 according to this embodiment. The image forming apparatus 1 is a full-color printer having a tandem-type intermediate transfer type image forming engine in which the image forming units PY, PM, PC, and PK are arranged along the intermediate transfer belt 44 . Examples of the recording material include sheet materials such as paper, plastic film, and cloth (hereinafter abbreviated as sheet S).

Each of the image forming units PY to PK is an electrophotographic image forming unit, and forms a toner image by executing an electrophotographic process. That is, the image forming unit PY uniformly charges the surface of the photosensitive drum 51, which is a photosensitive member, by the charging device 52, and writes an electrostatic latent image on the surface of the drum with laser light emitted by the laser scanner . This electrostatic latent image is developed with toner supplied from the developing device 20 to visualize a yellow toner image. The developing device 20 will be described later.

A similar process is carried out in parallel in the other image forming units PM, PC, and PK to form magenta, cyan, and black toner images. The configuration of each of the image forming units PY to PK is substantially the same except for the color of the toner used for development, so description thereof will be omitted. The toner images carried on the photosensitive drums 51 of the image forming portions PY to PK are primarily transferred onto the intermediate transfer belt 44 by the primary transfer rollers 47 at the primary transfer portion. A drum cleaner 53 removes deposits such as transfer residual toner remaining on the photosensitive drum 51 without being transferred to the intermediate transfer belt 44 .

An intermediate transfer belt 44 as an intermediate transfer body is wound around a tension roller 44a, a secondary transfer inner roller 45a, and a drive roller 44d, and conveyed by the drive roller 44d in a rotation direction R2 that rotates together with the rotation direction R1 of the photosensitive drum 51. be done. A secondary transfer outer roller 45b is disposed at a position facing the secondary transfer inner roller 45a with the intermediate transfer belt 44 interposed therebetween, and serves as a nip portion between the secondary transfer outer roller 45b and the intermediate transfer belt 44 for secondary transfer. A portion 45 is formed. Sheets S are fed one by one from a cassette, tray, or the like to the secondary transfer portion 45 . The toner image carried on the intermediate transfer belt 44 is secondarily transferred onto the sheet S by a bias electric field formed in the secondary transfer portion 45 . A belt cleaner 43 removes deposits such as untransferred toner remaining on the intermediate transfer belt 44 without being transferred to the sheet S. FIG.

After that, the sheet S is conveyed to the fixing device 46 . The fixing device 46 has a pair of rotating bodies for nipping and conveying the sheet S and a heat source such as a halogen lamp, and heats and presses the toner image while conveying the sheet S. As shown in FIG. As a result, the toner particles are melted and then fixed, so that an image fixed on the sheet S is obtained. The sheet S that has passed through the fixing device 46 is discharged to the outside of the image forming apparatus 1 .

A supply device 41 is connected to the developing device 20 of each of the image forming sections PY to PK. The replenishment device 41 includes a storage container that stores replenishment developer, and a hopper device that replenishes the developing device 20 while measuring the developer discharged from the storage container. The developer accommodated in the accommodation container contains toners of colors corresponding to the respective image forming portions PY to PK.

In this embodiment, a drum-shaped image carrier is used as the image carrier, but a belt-shaped image carrier can also be used. Also, the charging method, transfer method, cleaning method, and fixing method are not limited to the above methods.

[Developing device]
The developing device 20 of this embodiment will be described with reference to FIG. FIG. 2 is a cross-sectional view of the developing device 20 taken along a plane perpendicular to the longitudinal direction (rotation axis direction of the developing sleeve 24). The developing device 20 is a device that visualizes the electrostatic latent image formed on the photosensitive drum 51 with toner. The developing device 20 mainly includes a developing container 21 containing a two-component developer containing non-magnetic toner and a magnetic carrier, a first conveying screw 22, a second conveying screw 23, a developing sleeve 24, and a developing sleeve 24. It has regulation blades 25 and the like that face each other. The first conveying screw 22 and the second conveying screw 23 circulate inside the developing container 21 while stirring and conveying the developer inside the developing container 21 . The developing sleeve 24 carries developer and supplies the developer to the photosensitive drum 51 .

[Developer]
The developer used in this embodiment is composed of non-magnetic toner and magnetic carrier. The toner has a matrix made of a binder resin containing a colorant and additives added to the matrix. As the toner resin, a negatively chargeable polyester resin is used in this embodiment. The volume average particle diameter is preferably 4 μm or more and 10 μm or less. If the particle size of the toner is too small, it becomes difficult to friction with the carrier, making it difficult to control the amount of charge.

The carrier can be surface-oxidized or unoxidized metals such as iron, nickel, cobalt, manganese, chromium, rare earths, alloys thereof, or oxide ferrite. A ferrite carrier with a thickness of 40 μm was used. If the particle diameter of the carrier is too small, the carrier adheres to the photosensitive drum 51 during development, and if it is too large, the carrier disturbs the toner image during development. Further, in the present embodiment, 500 g of developer is accommodated in the developing container 21, and the toner weight ratio of the developer at the time of installation is set to 9%.

[Development container]
The interior of the developer container 21 is vertically partitioned into a supply chamber 31 and a recovery chamber 32 by a partition wall 30 extending along the developing sleeve 24 . The supply chamber 31 accommodates the developer and the first conveying screw 22 to supply the developer to the developing sleeve 24 . The collection chamber 32 collects the developer on the development sleeve 24 after passing through the image forming area Ar1 (that is, the development position where the electrostatic image formed on the photosensitive drum 51 is developed) and conveys it to the supply chamber 31 . , the developer and the second conveying screw 23 are accommodated. In addition, transfer portions (not shown) are provided at both ends of the developer container 21 in the longitudinal direction to allow passage of the developer between the supply chamber 31 and the recovery chamber 32 . The developer container 21 also has an opening 33 for exposing the developer sleeve 24 toward the photosensitive drum 51 .

[Conveyor screw]
Two conveying screws are used in the developing device 20 , and have spiral blades on their axes, and serve to agitate and convey the developer inside the developing container 21 . In this embodiment, the conveying screw arranged in the supply chamber 31 along the axial direction of the developing sleeve 24 is the first conveying screw 22, and the conveying screw arranged in the recovery chamber 32 along the axial direction of the developing sleeve 24 is used. Let the screw be the second conveying screw 23 . The first conveying screw 22 supplies the developer to the developing sleeve 24 while conveying the developer in the supply chamber 31 along the axial direction by rotating the rotating shaft with a screw motor. The second conveying screw 23 conveys the developer in the recovery chamber 32 in the axial direction opposite to the first conveying screw 22 and supplies the developer to the supply chamber 31 .

[Development sleeve]
The developing sleeve 24 is an example of a developer carrying member, and includes a magnet roller 26 , and the magnetic force of the magnet roller 26 causes the developing sleeve 24 to carry the developer. As the developing sleeve 24 rotates, it conveys the developer in the developer conveying direction, and has a function of supplying the developer to the electrostatic latent image formed on the photosensitive drum 51 . That is, the developing sleeve 24 is rotatably provided so as to carry and convey the developer toward the image forming area Ar1 where the electrostatic image formed on the photosensitive drum 51 is developed.

As shown in FIG. 3, the developing sleeve 24 has a carrying area 24a, which is an area where the developing sleeve 24 has the ability to convey the developer, and a non-carrying area 24b, which is an area where the developing sleeve 24 does not have the ability to convey the developer. have. In this embodiment, the surface of the carrying region 24a is roughened, and the surface of the non-carrying region 24b is not roughened. The unevenness here includes, for example, dents due to blast shot treatment, and grooves, engravings, thermal spraying, dents, etc. due to other treatments. The developing sleeve 24 carries and conveys the developer in the carrying area 24a. The carrying area 24a is a developer-coated area in which the developer can be carried on the surface, and corresponds to the maximum area (maximum image area) of the electrostatic latent image that can be formed on the surface of the photosensitive drum 51. area. In this embodiment, only one developing sleeve 24 is used, but the number of developing sleeves 24 is not limited to this, and may be two. Further, in the present embodiment, the surface of the carrying region 24a is roughened, and the surface of the non-carrying region 24b is not roughened, but the present invention is not limited to this. For example, even the carrying region 24a may not be subjected to unevenness treatment, or even the non-bearing region 24b may be subjected to unevenness treatment.

[Magnet roller]
As shown in FIG. 2, the magnet roller 26 has a developing magnetic pole S2 and magnetic poles N1, S1, N2, and N3 for conveying the developer. fixedly installed. The role of each pole will be described in association with the flow of developer transport. First, the developer sprung up by the first conveying screw 22 in the supply chamber 31 is carried on the surface of the developing sleeve 24 at the N1 pole, conveys the developer to the regulating blade 25, and is controlled by the regulating blade 25 for development. The amount of developer carried on the surface of the sleeve 24 is regulated. Next, the developer is conveyed from the S1 pole to the N2 pole, passes through it, and is supplied to the S2 pole facing the photosensitive drum 51 . The developer develops the electrostatic latent image as a toner image with the charged toner while the magnetic brush of the developer is brought into contact with the photosensitive drum 51 in the image forming area Ar1 by the magnetic field of the development magnetic pole S2. After passing through the image forming area Ar1, the developer conveyed to the N3 pole is released from the magnetic restraint force by the magnetic pole between the N3 pole and the N1 pole, and is collected in the collection chamber 32. FIG.

[Regulation blade]
The regulating blade 25 is an example of a regulating portion, and plays a role of adjusting the developer carried on the developing sleeve 24 to a predetermined amount. are arranged to face the In this embodiment, a plate-like non-magnetic regulating blade 25 extending along the axial direction (rotational axis direction) of the developing sleeve 24 is used. By changing the distance between the regulating blade 25 and the surface of the developing sleeve 24, the amount of developer carried on the developing sleeve 24 (the amount of developer supplied to the image forming area Ar1) can be adjusted. . That is, the regulating blade 25 regulates the amount of developer carried on the carrying area 24a (see FIG. 3).

However, if the gap between the regulating blade 25 and the developing sleeve 24 is too narrow, the amount of developer supplied to the image forming area Ar1 is reduced, which may make it impossible to form a desired toner image. In addition, foreign matter in the developer and aggregates of toner tend to clog, and the developer cannot be carried on the developing sleeve 24, which may make it impossible to form a toner image. On the other hand, if the gap between the regulating blade 25 and the developing sleeve 24 is too wide, the amount of developer conveyed to the image forming area Ar1 increases, causing clogging of the developer near the position facing the photosensitive drum 51 or jamming of the photosensitive drum 51. There is a possibility that the carrier may adhere. Therefore, in this embodiment, the gap between the regulating blade 25 and the developing sleeve 24 is set to 400 μm so that the amount of developer conveyed is 30 mg/cm ² . However, the interval between the regulating blade 25 and the developing sleeve 24 is not limited to 400 μm, and may be other values.

[Image forming area]
The image forming area Ar1 is a range in which the developing sleeve 24 and the photosensitive drum 51 are opposed to each other, and the toner on the developing sleeve 24 can fly to the photosensitive drum 51 . In this embodiment, the diameter of the developing sleeve 24 is 30 mm, the diameter of the photosensitive drum 51 is 50 mm, and the distance between the developing sleeve 24 and the photosensitive drum 51 in the image forming area Ar1 is set to 0.300 mm. . With this configuration, a toner image can be formed while the developer conveyed to the image forming area Ar1 is in contact with the photosensitive drum 51 .

A phenomenon within the image forming area Ar1 will be described. The developing sleeve 24 rotates in the rotation direction R3 during development, and conveys the developer regulated to an appropriate amount by the regulating blade 25 to the image forming area Ar1 facing the photosensitive drum 51 . In the image forming area Ar1, the developer forms a magnetic brush by the magnetic field of the magnet roller 26, supplies toner to the electrostatic latent image formed on the photosensitive drum 51, and obtains a toner image. At this time, a developing bias voltage obtained by superimposing a DC voltage and an AC voltage is applied to the developing sleeve 24 from a power source (not shown).

In this embodiment, the DC voltage is -400 V to -900 V, and the AC voltage is a rectangular wave with an amplitude voltage (Vpp/2) of 700 V and a frequency f of 12 kHz. However, the DC voltage value and the AC voltage waveform are not limited to these. In the image forming area Ar1, the photosensitive drum 51 is charged with a predetermined voltage, and the electrostatic latent image is formed by the laser so that the potential of the electrostatic latent image forming portion increases according to the density of the output image. . Further, in the image forming area Ar1, the developing sleeve 24 rotates in the same direction as the rotation direction R1 of the photosensitive drum 51. As shown in FIG. The peripheral speed ratio of the photosensitive drum 51 and the developing sleeve 24 is normally set between 1 and 3 times. As the peripheral speed ratio increases, the amount of toner supplied to the electrostatic latent image increases.

[opposing member]
A facing member 27, which is an example of a facing portion arranged to face the developing sleeve 24, is provided in a portion protruding from the regulation blade 25 toward the image forming area Ar1. That is, the facing member 27 is arranged to face the developing sleeve 24 downstream of the regulating blade 25 and upstream of the image forming area Ar1 (development position) with respect to the rotation direction R3 of the developing sleeve 24 .

The facing member 27 prevents the toner separated from the carrier by the rotation of the developing sleeve 24 from scattering outside the developing device 20 when the developer is conveyed from the regulating blade 25 toward the image forming area Ar1. playing a role. That is, the toner separated from the carrier is prevented from scattering and accumulating on, for example, the charging device 52 (see FIG. 1) outside the developing device 20 . The opposing member 27 may be welded to the developer container 21 or may be removable. In this embodiment, the facing member 27 is configured to be removable from the developer container 21 . In addition, the opposing member 27 has a sealing portion 27a having a shape protruding toward the central axis of the developing sleeve 24 so that the toner does not blow out in the longitudinal direction outside the non-carrying region 24b of the developing sleeve 24. (see FIG. 3).

[Seal member]
In the present embodiment, for the purpose of preventing toner agglomerates from being conveyed to the image forming area Ar1 and preventing the toner separated from the carrier from scattering in the range between the regulating blade 25 and the image forming area Ar1, A flexible sealing member 28 is employed. As shown in FIG. 3, the sealing member 28 is an example of a sealing portion, and is provided facing the carrying area 24a and the non-carrying area 24b so as to come into contact with the developer carried on the carrying area 24a. The seal member 28 is generally called Mylar and is made of a sheet material such as urethane rubber. The base end of the sealing member 28 is attached to the facing member 27 by an adhesive or the like, and the tip is a free end. In the present embodiment, the sealing member 28 has a role of breaking up toner aggregates by contacting the developer at the leading end thereof. That is, the sealing member 28 contacts the developer carried on the carrying area 24a (see FIG. 3) at the downstream end portion with respect to the rotation direction R3 of the developing sleeve 24. As shown in FIG.

[Toner scattering]
Here, the mechanism by which the toner scatters from the ends of the sealing member 28 in the longitudinal direction will be described with reference to FIGS. 6 and 7. FIG. 7A is a diagram viewed from the first direction D1 in FIG. 6, and FIG. 7B is a diagram viewed from the second direction D2 in FIG. Indicates air flow. As indicated by the arrow in FIG. 6, the toner is separated from the carrier by the rotational movement of the developing sleeve 24 while being conveyed from the regulating blade 25 to the image forming area Ar1. 7(a) and 7(b), an air current generated by the rotational motion of the developing sleeve 24 is formed between the non-carrying region 24b of the developing sleeve 24 at the end portion and the seal member 28. The toner flows into the opening and moves along with the air current.

The factors causing the opening in the non-bearing region 24b of the developing sleeve 24 are as follows. First, when the developing sleeve 24 carries the developer, the seal member 28 is lifted in the carrying area 24a. However, since the developer is not carried in the non-carrying region 24b at the end portion, a space is generated between the developing sleeve 24 and the seal member 28 by the amount of the floating of the seal member 28, forming an opening.

[Sealing member]
The configuration and operation characteristic of this embodiment will be described in detail below with reference to FIGS. 2 and 3. FIG. In this embodiment, a sealing member 29 is provided on the sealing member 28 so as to be sandwiched between the sealing member 28 and the non-carrying region 24b. The sealing member 29 is installed so as to seal the gap formed by the developing sleeve 24 , the opposing member 27 and the sealing member 28 at the end of the developing sleeve 24 , that is, the non-carrying region 24 b. The sealing member 29 is in contact with and sandwiched between the developing sleeve 24 and the sealing member 28 .

The thickness of the sealing member 29 is preferably 1 mm or less. The reason is as follows. The height of the magnetic spike formed by the developer carried by the developing sleeve 24 is about 0.4 to 1 mm. Therefore, if the thickness of the sealing member 29 exceeds 1 mm, the sealing member 28 is excessively lifted and a new opening is formed at the sealing member 29 portion. The height of the magnetic brush of the developer carried by the developing sleeve 24 is determined by the regulating blade 25 . Therefore, it is desirable that the sealing member 29 have a thickness equal to or less than the gap between the regulating blade 25 and the developing sleeve 24 .

3 shows the position of the sealing member 29 with respect to the axial direction of the developing sleeve 24. As shown in FIG. In the present embodiment, the sealing member 29 extends from the boundary between the carrying region 24a where the surface of the developing sleeve 24 is processed and the non-carrying region 24b where the surface is not processed, with respect to the longitudinal direction of the developing sleeve 24. (non-bearing region 24b). If the sealing member 29 is installed in the carrying area 24a, the flow of the developer on the developing sleeve 24 is blocked, and the transport of the developer to the image forming area Ar1 becomes unstable, resulting in density unevenness. I don't like it because it causes it to happen.

The material of the sealing member 29 will be mentioned. Since the purpose of the sealing member 29 is to seal the end opening, there is no need to specify the material. However, since the sealing member 29 is in contact with the rotating developing sleeve 24, it is not preferable to use a member that damages the surface of the developing sleeve 24 or that is easily damaged. Therefore, it is preferable to use a material such as urethane rubber or sponge sheet, which is the same material as the seal member 28 that is used in the structure that abuts on the rotating body such as the developing sleeve 24 and the photosensitive drum 51 .

As described above, according to the developing device 20 of the present embodiment, the sealing member 29 is provided on the sealing member 28 so as to be sandwiched between the sealing member 28 and the non-carrying region 24b. Therefore, when the developing sleeve 24 carries the developer, the seal member 28 is lifted by the developer, and the opening formed in the non-carrying region 24b can be sealed by the sealing member 29 . As a result, it is possible to prevent the toner from being scattered by the air current from the opening formed in the non-carrying area 24b.

Further, according to the developing device 20 of the present embodiment, the thickness of the sealing member 29 is equal to or less than the gap between the regulating blade 25 and the developing sleeve 24, and is equal to or less than 1 mm. Therefore, it is possible to prevent the sealing member 29 from excessively lifting the sealing member 28 and forming a new opening at the portion of the sealing member 29, thereby more effectively suppressing toner scattering.

Further, according to the developing device 20 of the present embodiment, since the sealing member 28 contacts the developer carried on the carrying area 24a at the downstream end portion in the rotational direction R3 of the developing sleeve 24, the aggregates of the toner are further broken up. be able to.

In the developing device 20 of the present embodiment described above, the case where the sealing member 29 is provided only between the sealing member 28 and the developing sleeve 24 has been described, but the present invention is not limited to this. For example, as shown in FIG. 4, a sealing member 129 may be provided between the seal member 28 and the opposing member 27 and the developing sleeve 24 . That is, the sealing member 129 is provided across the sealing member 28 and the opposing member 27 in the non-supporting region 24b, and is sandwiched between the sealing member 28 and the opposing member 27 and the non-supporting region 24b. In this case, the sealing member 129 can seal the air flow in the axial direction between the developing sleeve 24 and the opposing member 27, and when the sealing member 29 is provided only on the sealing member 28, the sealing member 29 Toner can be prevented from accumulating on the upstream side in the rotational direction R3.

(Example 1)
Using the developing device 20 of the present embodiment described above, the degree of image contamination due to toner blown out from both ends of the sealing member 28 was verified and compared with a conventional developing device without the sealing member 29 provided. . As for the method, the image forming apparatus 1 shown in FIG. The environment was set to normal temperature and normal humidity (23° C., 50% RH), and the image ratio was set to 2% to make it easy to see the occurrence of image staining. As a result, out of about 100,000 sheets S, not a single sheet S was stained with an image.

(Comparative example 1)
Continuous image formation was performed on 100,000 sheets using the image forming apparatus 1 shown in FIG. The environment was set to normal temperature and normal humidity (23° C., 50% RH) as in Example 1, and the image ratio was set to 2%. As a result, out of about 100,000 sheets S, about 70 sheets S had image stains. Therefore, it was confirmed that the occurrence of image contamination can be significantly reduced by installing the sealing member 29 in the developing device.

<Second embodiment>
A second embodiment of the invention will now be described in detail with reference to FIG. This embodiment differs from the first embodiment in that a cover member 34 is provided between the non-carrying region 24 b of the developing sleeve 24 and the sealing member 29 . However, since other configurations are the same as those of the first embodiment, the same reference numerals are used and detailed description thereof is omitted.

First, the necessity of the cover member 34 will be explained. The developing device is required to have a longer life (extend the total rotation time of the developing sleeve 24). In a configuration in which the developing sleeve 24 and the sealing member 29 are in contact with each other as shown in FIG. The time for which the working frictional force acts becomes longer. Therefore, there is a possibility that the sealing member 29 is worn and scraped as the service life is extended. When the sealing member 29 is worn and scraped, a gap is formed between the developing sleeve 24 and the sealing member 29, which may reduce the effect of suppressing toner scattering. Therefore, in the present embodiment, by providing a cover member 34 between the sealing member 29 and the developing sleeve 24, wear of the sealing member 29 is suppressed.

[Sealing member]
FIG. 7 shows a developing device 120 employing the cover member 34 and the sealing member 29. As shown in FIG. The cover member 34 is an example of a cover portion, and is arranged so as to cover the surface of the non-bearing area 24 b of the developing sleeve 24 facing the photosensitive drum 51 . The cover member 34 may be configured to cover only the non-supporting region 24b, or may be configured to cover a part of the supporting region 24a in addition to the non-supporting region 24b. In this embodiment, the cover member 34 is fixed to the developer container 21 with its upper end attached to the regulating blade 25 and its lower end attached to the lower edge 33 a of the opening 33 of the developer container 21 . That is, the cover member 34 is attached to the lower edge portion 33a on the downstream side of the opening 33 of the developer container 21 and the regulation blade 25 with respect to the rotation direction R3. It should be noted that the upper and lower ends of the cover member 34 are not limited to being attached to the developing container 21 by bonding as in the present embodiment, and the developing sleeve 24 can be connected to the developing sleeve 24 by bonding only one end and making the other end free. You may make it raise the adhesiveness of .

In this embodiment, the cover member 34 covers the surface of the non-carrying region 24 b of the developing sleeve 24 so as to be in contact therewith, and the upper and lower ends of the cover member 34 are adhered to the developer container 21 . Since the cover member 34 is in contact with the photosensitive drum 51 and the developing sleeve 24, a material that does not damage the surfaces of the photosensitive drum 51 and the developing sleeve 24 is used, such as urethane rubber or a sponge sheet. Further, by sprinkling a small amount of toner on the surface of the cover member 34, the surface roughness can be reduced.

The sealing member 29 is brought into contact with the non-rotating cover member 34 . As a result, no frictional force acts between the sealing member 29 and the cover member 34, and it is possible to greatly suppress the abrasion of the sealing member 29. FIG. On the other hand, the possibility that the cover member 34 is scraped due to friction with the developing sleeve 24 will be described. The surface roughness Ra of the sealing member 29 is approximately 0.5 μm, while the surface roughness Ra of the cover member 34 is approximately 2.5 μm. That is, the surface roughness of the surface of the cover member 34 facing the developing sleeve 24 is greater than the surface roughness of the sealing member 29 . Thus, by increasing the surface roughness, it is possible to reduce the contact area with the surface of the developing sleeve 24 and reduce the coefficient of friction. As a result, the frictional force acting between the surface of the developing sleeve 24 and the cover member 34 can be reduced, and the cover member 34 can be prevented from being scraped. As described above, by adopting the cover member 34 in addition to the sealing member 29, it is possible to extend the service life.

As described above, according to the developing device 120 of the present embodiment, since the cover member 34 is provided between the sealing member 29 and the developing sleeve 24, scraping due to wear of the sealing member 29 can be suppressed. For this reason, it is possible to suppress scattering of toner caused by scraping of the sealing member 29 due to abrasion, and to extend the life of the developing device 120 .

(Example 2)
Using the developing device 120 of the present embodiment described above, image contamination due to toner blowing out from both ends of the sealing member 28 and scraping of the sealing member 29 were verified. compared with the case As a method, the image forming apparatus 1 shown in FIG. 1 was used to continuously form images on 200,000 sheets S, and the image contamination of the sheets S and the scraping of the sealing member 29 were confirmed. The environment was set to normal temperature and normal humidity (23° C., 50% RH), and the image ratio was set to 2% to make it easy to see the occurrence of image staining. As a result, out of the 200,000 sheets S, not a single sheet S was stained with an image, and scraping of the sealing member 29 could not be confirmed.

(Comparative example 2)
Continuous image formation of 200,000 sheets was carried out using the image forming apparatus 1 shown in FIG. bottom. The environment was set to normal temperature and normal humidity (23° C., 50% RH) as in Example 2, and the image ratio was set to 2%. As a result, when 100,000 sheets were printed, no image smear occurred, but when 200,000 sheets were passed, 50 sheets S had image smudges. When checking the developing device after 200,000 sheets had passed, it was found that the sealing member 29 was scraped and an opening was formed. For this reason, when the number of sheets passed exceeds 100,000 sheets, the sealing member 29 is scraped, an opening is formed, and the toner scattered from the opening accumulates on the side surface of the developing container 21 below the developing sleeve 24 and accumulates. It can be inferred that image contamination occurred due to falling toner.

Therefore, when the sealing member 29 of the developing device that passed 100,000 sheets and 150,000 sheets was checked again, the sealing member 29 began to be scraped off after passing 100,000 sheets, and the side surface of the developing container 21 Toner adhered to the After passing 150,000 sheets of paper, it was confirmed that the sealing member 29 was scraped to the extent that the sealing effect was lost. Therefore, it was confirmed that by installing the sealing member 29 and the cover member 34 in the developing device, it is possible to significantly reduce the occurrence of image contamination and extend the life of the developing device.

Reference Signs List 20, 120 Developing device 21 Developing container 24 Developing sleeve (developer carrier) 24a Carrying area 24b Non-carrying area 25 Regulating blade (regulating portion) 27 Opposing member (opposing portion ), 28... Seal member (seal portion) 29, 129... Seal member 33... Opening portion 33a... Lower edge portion 34... Cover member (cover portion) Ar1... Image forming area (development position)

Claims (9)

a developer container containing developer containing toner and carrier;
A rotatable developer carrier that carries and transports developer toward a development position where an electrostatic image formed on the image carrier is developed, in a region where the developer carrier has a developer transport capability a developer carrying member having a carrying area and a non-carrying area which is an area having no developer carrying ability of the developer carrying member;
a regulating portion that regulates the amount of developer carried on the carrying area;
a facing portion arranged to face the developer carrier downstream from the regulating portion and upstream from the developing position with respect to the rotation direction of the developer carrier;
a flexible sealing portion provided opposite to the carrying area and the non-carrying area so as to come into contact with the developer carried on the carrying area;
a sealing member provided in the seal portion so as to be sandwiched between the seal portion and the non-carrying region;
A developing device characterized by: wherein the sealing member has a thickness equal to or less than the gap between the regulating portion and the developer carrier;
2. The developing device according to claim 1, wherein: In the carrying area, the surface of the developer carrying member is subjected to unevenness treatment,
In the non-carrying region, the surface of the developer carrying member is not subjected to unevenness treatment.
3. The developing device according to claim 1, wherein: The sealing member is made of urethane rubber,
4. The developing device according to any one of claims 1 to 3, characterized in that: The sealing portion is in contact with the developer carried on the holding area at a downstream end portion in the rotational direction.
5. The developing device according to any one of claims 1 to 4, characterized in that: The seal portion is made of a sheet material,
6. The developing device according to any one of claims 1 to 5, characterized in that: The sealing member is provided across the sealing portion and the facing portion in the non-supporting region, and is sandwiched between the sealing portion and the facing portion and the non-supporting region.
7. The developing device according to any one of claims 1 to 6, characterized in that: a cover portion provided between the sealing member and the non-carrying region and fixed to the developer container so as to be in contact with the non-carrying region;
The surface roughness of the surface of the cover facing the developer carrier is greater than the surface roughness of the sealing member.
8. The developing device according to any one of claims 1 to 7, characterized in that: The developer container has an opening for exposing the developer carrier,
The cover portion is attached to a downstream edge portion of the opening of the developer container and the regulation portion with respect to the rotation direction of the developer carrier.
9. The developing device according to claim 8, wherein:

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