JP7353885B2 - Developing device, cartridge, image forming device - Google Patents

Description

The present invention relates to a developing device and a process cartridge used in copying machines, printers, etc. that use electrophotography.

An image forming apparatus that uses an electrophotographic method forms a developer image by supplying developer to an electrostatic latent image formed by scanning exposure on a photosensitive drum, which is an image carrier, and forms a developer image on a sheet material, etc. An image is formed through a process of transferring and fixing it onto a recording material and outputting it.
In recent years, in image forming apparatuses using an electrophotographic image forming process, the lifespan of process cartridges has been lengthened. There is a method for replenishing developer. This method of replenishing the process cartridge with developer has a problem called background smearing, which occurs when the supplied new developer and the old developer in the process cartridge are insufficiently mixed. In order to suppress this, a technology is developed in which multiple stirring screws are installed in the developer storage chamber where the developer of the process cartridge is stored, and the supplied developer is sufficiently mixed with the existing developer in the process cartridge. There is (Patent Document 1).

Japanese Patent Application Publication No. 2019-003033

However, such a configuration has the problem of increasing the size and cost of the device. Therefore, there has been a desire for a developing device that can suppress background smearing caused by insufficient mixing of the developer without using a plurality of screws for mixing the developer.

An object of the present invention is to realize a configuration in which a developer storage chamber is provided with a replenishment port that can replenish developer, and to provide a developing device that can improve the mixing properties of the developer in the storage chamber and suppress background smearing. It is to provide.

In order to achieve the above object, the developing device according to the present invention includes:
a frame body including a storage chamber for storing developer and a replenishment port for replenishing the developer into the storage chamber from the outside;
The sheet member includes a rotating shaft rotatably supported by the frame, and a seat member having one end fixed to the rotating shaft and the other end being a free end and rotatable in accordance with the rotational movement of the rotating shaft. and a stirring member that stirs the developer in the storage chamber;
A developing device comprising:
The free end of the sheet member is capable of contacting the inner wall surface of the storage chamber in which the replenishment port is formed, and in a region of the sheet member that is capable of contacting the inner wall surface of the storage chamber. A through hole is provided that penetrates the sheet member in the thickness direction ,
The through hole is
When viewed from the axial direction of the rotating shaft portion,
The position where the sheet member is fixed to the rotating shaft portion is defined as position A,
The distance between position A and the center position of the replenishment port in the rotational direction of the rotating shaft portion is L,
In the sheet member, the length from position A to one end of the through hole closer to the free end of the sheet member is S1,
When the length from position A in the sheet member to the other end of the through hole of the sheet member closer to the rotating shaft portion is S2,
S1>L>S2
It is characterized in that it is provided on the sheet member so that the following is true .

Moreover, in order to achieve the above object, the cartridge in the present invention includes:
The above developing device,
an image carrier on which a developer image is formed;
It is characterized in that it can be attached to and detached from the main body of the image forming apparatus.

Furthermore, in order to achieve the above object, the image forming apparatus according to the present invention includes:
At least one of the above-mentioned developing device or the above-mentioned cartridge;
A transfer member;
It is characterized by having the following.

According to the present invention, it is possible to suppress background smear caused by developer replenishment without using a stirring screw or the like that requires an enlarged device.

A plan view of a stirring member according to Embodiment 1 Schematic diagram of an image forming apparatus according to Embodiment 1 A schematic cross-sectional view of a process cartridge according to Embodiment 1 Schematic cross-sectional view (longitudinal cross-section) of the developing device according to Embodiment 1 Schematic cross-sectional view (horizontal cross-section) of the developing device according to Embodiment 1 Conceptual diagram of a stirring member according to Embodiment 1 A diagram illustrating toner circulation according to Embodiment 1 A diagram illustrating toner circulation according to a comparative example of Embodiment 1 Schematic sectional view of a process cartridge according to Embodiment 3 Schematic sectional view of a developing device according to Embodiment 3 Conceptual diagram of a stirring member according to Embodiment 3 Conceptual diagram of a stirring member according to a modification of Embodiment 3 Schematic sectional view of a process cartridge according to Embodiment 4 Schematic sectional view of a developing device according to Embodiment 4 Conceptual diagram of a stirring member according to Embodiment 4 Conceptual diagram of a stirring member according to a modification of Embodiment 4 Schematic sectional view of a developing device according to another embodiment

EMBODIMENT OF THE INVENTION Below, with reference to drawings, the form for implementing this invention is illustratively described in detail based on an Example. However, the dimensions, materials, shapes, and relative arrangement of the components described in this embodiment are not intended to limit the scope of the present invention to these unless otherwise specified. Further, the functions, materials, shapes, etc. of the members that have been explained once in the following explanation are the same as those in the first explanation unless otherwise specified.

[Embodiment 1]
[Overall configuration of image forming apparatus]
First, the overall configuration of an electrophotographic image forming apparatus (hereinafter referred to as an image forming apparatus) according to the present invention will be described. FIG. 2 is a schematic cross-sectional view of the image forming apparatus according to the first embodiment. The image forming apparatus 100 of this embodiment is a full-color laser printer that employs an in-line method and an intermediate transfer method. The image forming apparatus 100 can form a full-color image on a recording material 12 (eg, recording paper, plastic sheet, cloth, etc.) according to image information. Image information is input to the apparatus main body 100A from an image reading device connected to the apparatus main body 100A of the image forming apparatus, or from a host device such as a personal computer communicably connected to the apparatus main body 100A.
The image forming apparatus 100 includes a plurality of image forming sections, a first, a second, and a third for forming images of each color of yellow (Y), magenta (M), cyan (C), and black (K), respectively. , fourth image forming sections SY, SM, SC, and SK. These first to fourth image forming sections each include a process cartridge 7, etc., which will be described later. In this embodiment, the first to fourth image forming units SY, SM, SC, and SK are arranged in a line in a direction intersecting the vertical direction.
In this embodiment, the configurations and operations of the first to fourth image forming sections SY, SM, SC, and SK are substantially the same except that the colors of the images to be formed are different. Therefore, in the following, unless a particular distinction is required, the suffixes Y, M, C, and K given to the symbols to indicate elements provided for one of the colors will be omitted, and they will be generally referred to as explain.

FIG. 3 shows a cross-sectional view of the process cartridge 7 disposed in the image forming apparatus 100 in this embodiment.
In the present embodiment, the image forming apparatus 100 has four process cartridges 7 arranged in parallel in a direction intersecting the vertical direction. In these four process cartridges, four drum-shaped electrophotographic photosensitive members, that is, photosensitive drums 1 as shown in FIG. 3 are arranged as a plurality of image carriers. The photosensitive drum 1 is rotationally driven in the direction of an arrow A (clockwise) in the figure by a drive means (drive source) not shown. Around the photosensitive drum 1, there is a charging roller 2 as a charging means that charges the surface of the photosensitive drum 1 uniformly, and an electrostatic image (electrostatic latent image) is formed on the photosensitive drum 1 by irradiating a laser with a laser based on image information. A scanner unit (exposure device) 3 is arranged as an exposure means for forming. Further, around the photosensitive drum 1, there is a developing unit (developing device) 4 as a developing means for developing the electrostatic image as a toner image, and a developing unit (developing device) 4 for removing toner remaining on the surface of the photosensitive drum 1 after transfer (residual toner after transfer). A cleaning member 6 is disposed as a cleaning means for cleaning. Furthermore, an intermediate transfer belt 5 as an intermediate transfer member for transferring the toner image on the photosensitive drum 1 onto the recording material 12 is arranged opposite to the four photosensitive drums 1 .
In this embodiment, the developing unit 4 uses toner 80, which is a non-magnetic one-component developer, as the developer. Further, in this embodiment, the developing unit 4 performs reversal development by bringing the developing roller 17, which serves as a developer carrier, into contact with the photosensitive drum 1. That is, in the present embodiment, the developing unit 4 transfers the toner 80 charged to the same polarity as that of the photosensitive drum 1 (negative polarity in this embodiment) to the portion of the photosensitive drum 1 where the charge is attenuated by exposure (the image The electrostatic image is developed by attaching it to the exposed area.

In this embodiment, the photosensitive drum 1, the charging roller 2 as a process means acting on the photosensitive drum 1, the developing unit 4, and the cleaning member 6 are integrated, that is, integrally formed into a cartridge. A process cartridge 7 shown in FIG. The process cartridge 7 can be attached to and removed from the image forming apparatus 100 via attachment means such as an attachment guide and a positioning member provided in the apparatus main body 100A of the image forming apparatus. In this embodiment, the process cartridges 7 for each color all have the same shape, and the process cartridges 7 for each color include yellow (Y), magenta (M), cyan (C), and blank ( K) toner of each color is stored.
In this embodiment, as shown in FIG. 2, four color toner containers 9 are provided below the four color process cartridges 7, and a toner amount detecting means (not shown) provided in the developing unit 4 and an image Toner is appropriately supplied to the developing unit 4 based on the printing information of the forming device. When toner is supplied, the toner discharged from the toner container 9 to the toner transport device is transported upward by the rotation of a screw provided in the transport path, and is then conveyed from the supply port provided in the developing unit 4. Supplied.

Next, the intermediate transfer belt 5, which is an endless belt and serves as an intermediate transfer member, comes into contact with all the photosensitive drums 1 and circulates (rotates) in the direction of arrow C (counterclockwise) in the figure. The intermediate transfer belt 5 is stretched around a driving roller 51, a secondary transfer opposing roller 52, and a driven roller 53 as a plurality of supporting members.
On the inner peripheral surface side of the intermediate transfer belt 5, four primary transfer rollers 8, which serve as primary transfer means, are arranged in parallel so as to face each photosensitive drum 1. The primary transfer roller 8 presses the intermediate transfer belt 5 toward the photosensitive drum 1 to form a primary transfer portion where the intermediate transfer belt 5 and the photosensitive drum 1 come into contact. Then, a bias having a polarity opposite to the normal charging polarity of the toner is applied to the primary transfer roller 8 from a primary transfer bias power source (high voltage power source) as a primary transfer bias applying means (not shown). As a result, the toner image on the photosensitive drum 1 is transferred onto the intermediate transfer belt 5 (primary transfer).

Further, a secondary transfer roller 54 serving as a secondary transfer means is arranged at a position facing the secondary transfer opposing roller 52 on the outer peripheral surface side of the intermediate transfer belt 5. The secondary transfer roller 54 is in pressure contact with the secondary transfer opposing roller 52 via the intermediate transfer belt 5, and forms a secondary transfer portion where the intermediate transfer belt 5 and the secondary transfer roller 9 are in contact with each other. Then, a bias having a polarity opposite to the normal charging polarity of the toner is applied to the secondary transfer roller 9 from a secondary transfer bias power source (high voltage power source) serving as a secondary transfer bias applying means (not shown). As a result, the toner image on the intermediate transfer belt 5 is transferred onto the recording material 12 (secondary transfer).
A pickup roller 144, a conveyance roller 148, and a registration roller 160 are provided as conveyance means for conveying the recording material 12 to the secondary transfer section. The recording material 12 is fed by a pickup roller 144 at a predetermined timing from the start of exposure. Then, it is transported by the transport roller 148 and further transported by the registration roller 160 to a position in front of the secondary transfer roller 54 . Thereafter, when the leading edge of the recording material 12 is detected by a paper detection sensor (not shown), the conveyance roller 148 and registration roller 160 are temporarily stopped and placed in a standby state. Then, at a predetermined timing, driving of the conveyance roller 148 and the registration roller 160 is restarted. Then, the recording material 12 in the standby state starts to move, is conveyed to the secondary transfer section, and is conveyed toward the secondary transfer section. By carrying out paper feeding and paper refeeding at predetermined timings from the start of exposure, the toner image on the intermediate transfer belt 5 is perfectly overlapped with the recording material 12 at the secondary transfer section, and the recording material The toner image is secondarily transferred onto 12 without positional deviation.

A series of image forming operations will be explained. First, the surface of the photosensitive drum 1 is uniformly charged by the charging roller 2. Next, the surface of the charged photosensitive drum 1 is scanned and exposed by a laser beam emitted from the scanner unit 3 according to the image information, and an electrostatic image according to the image information is formed on the photosensitive drum 1. Next, the electrostatic image formed on the photosensitive drum 1 is developed by the developing unit 4 as a toner image (developer image). The toner image formed on the photosensitive drum 1 is transferred (primary transfer) onto the intermediate transfer belt 5 by the action of the primary transfer roller 8 . For example, when forming a full-color image, the above-mentioned process is performed sequentially in the first to fourth image forming sections SY, SM, SC, and SK, and toner images of each color are then superimposed on the intermediate transfer belt 5. primary transfer is performed.

Thereafter, the recording material 12 is conveyed to the secondary transfer section in synchronization with the movement of the intermediate transfer belt 5. The four-color toner images on the intermediate transfer belt 5 are secondarily transferred onto the recording material 12 all at once by the action of the secondary transfer roller 54 that is in contact with the intermediate transfer belt 5 via the recording material 12 .
The recording material 12 onto which the toner image has been transferred is conveyed to a fixing device 10 as a fixing means. The toner image is fixed on the recording material 12 by applying heat and pressure to the recording material 12 in the fixing device 10 .

Further, the primary transfer residual toner remaining on the photosensitive drum 1 after the primary transfer process is removed and collected by the cleaning member 6. Further, secondary transfer residual toner remaining on the intermediate transfer belt 5 after the secondary transfer process is cleaned by an intermediate transfer belt cleaning device 11. The primary transfer roller 8 and the secondary transfer roller 54 in the above description correspond to the transfer member of this embodiment.
Note that the image forming apparatus 100 can also form monochrome or multicolor images using only one desired image forming section or using only some (but not all) image forming sections. It looks like this.

[Process cartridge configuration]
Next, the overall configuration of the process cartridge 7 installed in the image forming apparatus 100 of this embodiment will be described. In this embodiment, the structure and operation of the process cartridges 7 for each color are substantially the same except for the type (color) of the toner 80 contained therein.

FIG. 3 is a schematic cross-sectional view of the process cartridge 7 of the first embodiment. The attitude of the process cartridge 7 in FIG. 3 is the attitude when it is installed in the main body of the image forming apparatus, and when the positional relationships and directions of each member of the process cartridge 7 are described below, the positional relationships and directions in this attitude will be described. Indicates direction, etc.

The process cartridge 7 is configured by integrating a photosensitive unit 13 including a photosensitive drum 1 and the like, and a developing unit 4 including a developing roller 17 and the like.
The photoreceptor unit 13 has a cleaning frame 14 as a frame that supports various elements within the photoreceptor unit 13 . The photosensitive drum 1 is rotatably attached to the cleaning frame 14 via a bearing (not shown). The photosensitive drum 1 is driven to rotate in the direction of arrow A (clockwise) in the figure according to the image forming operation by transmitting the driving force of a drive motor as a drive means (drive source) not shown to the photoconductor unit 13. be done. In this embodiment, the photosensitive drum 1, which is the center of the image forming process, is an organic photosensitive drum 1 in which the outer peripheral surface of an aluminum cylinder is coated with a subbing layer, a carrier generation layer, and a carrier transport layer, which are functional films, in this order. I am using it.
Further, a cleaning member 6 and a charging roller 2 are arranged in the photoconductor unit 13 so as to be in contact with the circumferential surface of the photoconductor drum 1 . Transfer residual toner removed from the surface of the photosensitive drum 1 by the cleaning member 6 falls and is stored in a cleaning frame 14 (hereinafter referred to as a waste toner box). The charging roller 2, which is a charging means, is driven to rotate by bringing a conductive rubber roller portion into pressure contact with the photosensitive drum 1.

Here, a predetermined DC voltage is applied to the core metal of the charging roller 2 with respect to the photosensitive drum 1 during the charging process, so that the surface of the photosensitive drum 1 has a uniform dark potential (Vd). is formed. The spot pattern of the laser light emitted according to the image data by the laser light from the scanner unit 3 described above exposes the photosensitive drum 1, and the exposed area is charged on the surface by carriers from the carrier generation layer. disappears and the potential decreases. As a result, an electrostatic latent image is formed on the photosensitive drum 1, with the exposed areas having a predetermined bright potential (Vl) and the unexposed areas having a predetermined dark potential (Vd). In this example, Vd=-500V and Vl=-100V.

On the other hand, the developing unit 4 includes a developing frame 16 as a frame that supports various elements within the developing unit 4 . The developing unit 4 is provided with a developing roller 17 that is a developer carrier for supporting toner 80 as a developer. A developing chamber in which a toner supplying roller 20 as a supplying member for supplying toner 80 to the developing roller 17 is disposed is located above the toner storage chamber 18 (described later) in the direction of gravity when in use. is formed by. Further, in the developing unit 4, a toner storage chamber 18 having a toner storage section (developer storage section) for storing toner 80 located below the toner supply roller 20 in the direction of gravity is also formed by the development frame 16. Further, the developing unit 4 has an upper wall portion and a lower wall portion that separate the developing chamber and the toner storage chamber.
Further, the toner supply roller 20 forms a toner nip N (a portion where the toner is sandwiched between the development roller 17 and the toner supply roller 20) between it and the development roller 17, and rotates.
A stirring member 22 is provided within the toner storage chamber 18 . The stirring member 22 is used to stir the toner 80 contained in the toner storage chamber 18 and also to transport the toner 80 toward the upper part of the toner supply roller 20 in the direction of arrow G in the figure.

The developing blade 21 is disposed below the developing roller 17, contacts the developing roller 17 with a counter, and regulates the coating amount of the toner 80 supplied by the toner supply roller 20 and applies electric charge. In this embodiment, a thin plate made of SUS in the shape of a leaf spring with a thickness of 0.1 mm is used as the developing blade 21, and the spring elasticity of the thin plate is used to generate contact pressure, and the surface of the plate is used to protect the toner and the developing roller 17. is brought into contact with. Here, the developing blade is not limited to this, and may be a thin metal plate made of phosphor bronze, aluminum, or the like. Alternatively, the surface of the developing blade 21 may be coated with a thin film of polyamide elastomer, urethane rubber, urethane resin, or the like.
The toner 80 is triboelectrically charged by the friction between the developing blade 21 and the developing roller 17, and at the same time, the layer thickness is regulated. Further, in this embodiment, a predetermined voltage is applied to the developing blade 21 from a blade bias power source (not shown) to stabilize the toner coating. In this embodiment, V=-500V was applied as the blade bias.

The developing roller 17 and the photosensitive drum 1 rotate so that their respective surfaces move in the same direction (in the present embodiment, from the bottom to the top) at opposing portions.
In this embodiment, the developing roller 17 is placed in contact with the photosensitive drum 1, but the developing roller 17 may be placed close to the photosensitive drum 1 with a predetermined distance therebetween. good.
In this embodiment, in response to a predetermined DC bias applied to the developing roller 17, the toner 80 that is negatively charged by frictional charging is applied to the bright area potential area in the developing area in contact with the photosensitive drum 1 based on the potential difference. The electrostatic latent image is transferred only to the electrostatic latent image. In this embodiment, by applying V=-300V to the developing roller 17, a potential difference ΔV=200V with respect to the bright area potential portion was formed, and a toner image was formed.
The toner supply roller 20 is an elastic sponge roller with a foam layer formed around the outer periphery of a conductive metal core. The toner supply roller 20 and the developing roller 17 are in contact with each other with a predetermined amount of penetration. The toner supply roller 20 and the developing roller 17 rotate in opposite directions with a circumferential speed difference in the nip portion N, and through this operation, the toner supply roller 20 supplies toner to the developing roller 17. .

[Toner supply to the toner storage chamber]
As shown in FIG. 2, in this embodiment, toner containers 9 for each color are removably disposed below the process cartridges 7 for each color and at a position corresponding to the outside of the developing unit 4. . The toner container 9 is configured to be able to discharge a desired amount of toner by rotationally driving a screw (not shown) provided inside. The discharged toner is transferred from the toner conveying device 19 to a toner receiving port provided in the upper developing unit 4 via a toner conveying path. The toner conveyance device 19 has a space for receiving the toner discharged from the toner container 9, and also has a drive transmission function for driving a screw (not shown) provided inside the conveyance path. The toner delivered to the toner receiving port of the developing unit 4 is supplied to the toner storage chamber 18 from the supply port 23 provided at the center in the longitudinal direction via a toner conveying path provided in the developing unit 4. (Figure 6). Note that the above-mentioned longitudinal direction is a direction parallel to the axial direction of the rotating shaft of the developing roller 17, and also a direction parallel to the axial direction of the stirring shaft 24 of the stirring member 22, which will be described later. In this embodiment, the toner supply is controlled so that the toner 80 in the developing unit 4 is maintained at 250 g, the toner supply amount is determined based on the print information of the image forming apparatus, and the toner supply amount is determined based on the print information of the image forming apparatus. A method is adopted in which the toner is discharged from the toner container 9.
Here, the method of discharging the toner from the toner container 9, the method of transporting the toner, and the toner supply control are not limited to the methods of this embodiment, and may be methods other than those of this embodiment.

[Configuration of stirring member]
The stirring member, which is a feature of the present invention, will be explained using FIG. 4. FIG. 4 is a cross section of the developing device taken along the line α in FIG. The stirring member 22 of this embodiment includes a stirring shaft 24 as a rotary shaft part that is rotatably supported, and a flexible member configured such that one end is fixed to the stirring shaft 24 and the other end is a free end. It consists of a sheet member 25 having. This sheet member 25 is rotatable as the stirring shaft 24 rotates. Furthermore, the sheet member 25 is provided with an agitation promoting hole 26, which is a feature of this embodiment, in the axial direction of the agitation shaft 24, in alignment with the position of the replenishment port 23 provided on the inner wall surface of the frame 16 of the developing unit 4. It is provided at a central position in the longitudinal direction, which is a parallel direction. The sheet member 25 of the stirring member 22 stirs the toner 80 in the toner storage chamber 18 as the stirring shaft 24 rotates. Further, the agitating member 22 supplies the toner 80 into the developing chamber provided above while stirring, thereby supplying the toner 80 to the developing roller 17 via the supply roller and developing it on the photosensitive drum 1. .

[Mixing of toner in the stirring chamber]
The toner 80a (hereinafter referred to as "new toner") supplied into the toner storage chamber from the toner container 9 via the toner transport device 19 and the replenishment port 23 is stored in the toner storage chamber 18 before being replenished. Together with a certain toner 80b (hereinafter referred to as "old toner"), the toner is stirred and conveyed within the toner storage chamber 18 by the rotation of the sheet member 25.
Here, as the use of the developing unit 4 progresses and toner circulation is repeated within the developing unit 4, the deterioration of the old toner 80b in the toner storage chamber 18 progresses. Deterioration here means that the toner resin is worn or deformed due to mechanical rubbing, or that external additives added to the surface are liberated or embedded in the resin, causing the toner to be replenished from the toner container 9. This refers to a phenomenon in which behavior such as charging characteristics changes compared to a new toner 80a.
That is, when the developing unit 4 is used more and the old toner 80b deteriorates, a difference in charging characteristics occurs between the new toner 80a and the old toner 80b. If the charging characteristics of the toner differ, when the electrostatic latent image formed on the photosensitive drum 1 is visualized, the amount of toner to fill the electrostatic latent image may change, and the potential of not only the bright area but also the dark area may change. Toner may fly away due to the electric potential. As a result, problems such as density unevenness and background stains occur.

In order to suppress the occurrence of such issues, the following is necessary. That is, even if a difference in charging characteristics occurs between the new toner 80a and the old toner 80b, the new toner 80a and the old toner 80b are sufficiently stirred in the toner storage chamber 18, and the new toner 80a and the old toner 80b are mixed in the old toner 80b. It is necessary to prevent the new toner 80a from being unevenly distributed.

In the present invention, the agitation promoting hole 26, which is a through hole penetrating the sheet member 25 in the thickness direction as shown in FIG. The positional relationship with the agitation promoting hole 26 and the length of the agitation promoting hole 26 are defined as described below. With this configuration, scumming can be suppressed without using additional members such as stirring screws. The detailed mechanism will be explained below.

First, the difference in the toner agitation process depending on the presence or absence of agitation promoting holes will be explained with reference to FIGS. 7 and 8. FIG. 7A shows a state in which toner 80a is replenished from the replenishment port 23 when the stirring member 22 is in the phase shown in the figure. Thereafter, as the agitation member 22 is rotated, the toner 80a is pushed out and transported to the sheet member 25, but since there is no pressure on the toner in the agitation promotion hole 26, some of the toner 80a is transferred to the agitation promotion hole 26. 26 (FIG. 7(b)). At this time, a pressure difference is generated in the vicinity of the agitation promoting hole, and the toner flows in the direction opposite to the rotational direction of the agitation member 22. When the sheet member 25 further approaches the opening of the developing chamber (FIG. 7(c)), the toner 80a being transported and the toner 80b stored in the storage chamber progresses, and the toner 80a that has passed through the stirring promotion hole 26 is Mixing is also progressing. Thereafter, when the toner is sent to the developing chamber, the toner has been sufficiently mixed, so that background smearing due to toner replenishment can be suppressed.

FIG. 8 shows a stirring schematic diagram of a sheet member without stirring promotion holes as Comparative Example 1 of the present embodiment. Similarly to FIG. 7, when the toner 80a is replenished from the replenishment port 23 when the stirring member is in the phase shown in FIG. Ru. Thereafter, as the sheet member approaches the opening of the developing chamber, the toner 80a and the toner 80b in the storage chamber progress to mix (FIGS. 8(b) and 8(c)). is difficult to mix (Figure 8(d)). In particular, as the process cartridge 7 is used more and more, the charging ability of the toner in the toner storage chamber changes due to embedding or detachment of external additives. In such a case, due to the difference in charging ability between the old toner 80b and the new toner 80a, uneven charging of the toner occurs, resulting in background smearing.

Based on the above, an effect confirmation experiment was conducted to verify what positional relationship the stirring promotion hole 26 is provided with respect to the replenishment port 23 to be effective. FIG. 6 is a schematic diagram showing the positional relationship between the stirring promotion hole and the replenishment port when viewed from the axial direction of the stirring shaft 24, which is the rotating shaft portion. Definitions of symbols in FIG. 6 are shown below.
A: Position L where the sheet member 25 of the stirring member 22 is fixed to the stirring shaft 24: Distance S1 between position A and the center position of the supply port 23 in the rotational direction of the stirring shaft 24: In the sheet member 25, Length S2 from position A to one end of the stirring promotion hole 26 closer to the free end of the sheet member 25: Length S2 from position A to one end of the stirring promotion hole 26 of the sheet member 25 closer to the stirring shaft 24 of the sheet member 25 The relative size relationship of the above symbols below the length to the other end of the promoting hole 26 is not when the sheet member 25 of the stirring member 22 is actually rotated, but when the sheet member 25 is bent. There is no size relationship on the drawing. However, since S1 and S2 represent the length from position A to a certain point of the sheet member 25 itself, the sheet member 25 may be bent.

[Effect confirmation experiment]
In order to verify the effect of this example, an experiment was conducted by changing the size of S1. In Example 1, Example 2, and Example 3, the size of S1 is changed, but in each case, as the stirring shaft 24 rotates, the stirring promotion hole 26 passes near the supply port 23. They have something in common. As comparative examples, Comparative Example 1 is a case where the stirring promotion hole 26 is not provided, and Comparative Example 2 is a case where S1 is made smaller than L and the stirring promotion hole 26 does not pass near the replenishment port 23. Further, in this experiment, the length of the stirring promotion holes 26 in the longitudinal direction was uniformly set to 30 mm. A two-sheet intermittent printing durability test was conducted under a high temperature and high humidity environment (temperature: 30° C., humidity: 80%). In this printing durability, horizontal lines with an image ratio of 1% were printed. In addition, in this experiment, the process cartridge 7 was started with 200 g of toner filled, and control was performed such that 10 g of toner was replenished from the toner container 9 every time the toner decreased by 10 g. Then, printing durability was carried out until the amount of process cartridge 7 used reached 100%, and the occurrence of background smudge was judged according to the criteria shown below.

○ Background smudge evaluation Background smear is an image defect in which toner is slightly developed in unexposed areas that are not normally printed. Stop the image forming apparatus while printing a solid white image. After development and before transfer, the toner on the photosensitive drum is transferred to a transparent tape, and the tape with the toner attached is attached to a recording paper or the like. Also, a tape to which no toner is attached is also pasted onto the same recording paper at the same time. The optical reflectance of the green filter was measured using an optical reflectance measuring device (TC-6DS manufactured by Tokyo Denshoku Co., Ltd.) from above the tape attached to the recording paper, and the optical reflectance was subtracted from the reflectance of the tape to which no toner was attached. The amount of reflectance of the background dirt was determined and evaluated as the amount of background dirt. The amount of scumming was measured at three or more points on the tape and the average value was calculated.

○: The amount of background stain is less than 3.0%.
×: The amount of background stain is 3.0% or more.

The evaluation results are shown in Table 1.

In Examples 1, 2, and 3, no scumming occurred. This means that even if there is a difference in the absolute value of S1, it is important to maintain the relationship S1>L>S2. The reason why background staining did not occur will be explained. First, when S1 is larger than L as in Examples 1 to 3, the end of the stirring promotion hole 26 that is closer to the free end of the sheet member 25 reaches the replenishment port 23. Then, when the stirring shaft 24 of the stirring member 22 rotates, the sheet member 25 comes into contact with the inner wall surface of the toner storage chamber 18 as the stirring shaft 24 rotates. Then, the position of the agitation promoting hole 26 of the sheet member 25 is arranged to overlap with the position where the replenishment port 23 of the toner storage chamber 18 is provided. As a result, the new toner 80a that tends to accumulate near the replenishment port passes through the agitation promotion hole 26, is agitated in a portion of the sheet member 25 where the agitation promotion hole 26 is not provided, and can be mixed with the old toner 80b.
On the other hand, in Comparative Example 1 of the present embodiment, there was no agitation promoting hole, and it is thought that scumming occurred due to the mechanism explained using FIG. 8 described above.
Comparative example 2 is a case where S1 is smaller than L. Under such conditions, the end of the stirring promotion hole 26 that is closer to the free end of the sheet member 25 does not reach the replenishment port 23 . Then, even if the sheet member 25 comes into contact with the inner wall surface of the toner storage chamber 18 as the stirring shaft 24 rotates, the position of the stirring promotion hole 26 does not overlap with the position where the replenishment port 23 is provided. As a result, since the agitation promoting hole 26 cannot pass near the replenishment port, the new toner 80a and the old toner 80b cannot be mixed, and the effect on scumming is reduced. To summarize the above, it can be seen that the effect of the agitation promoting hole on background staining depends on the magnitude relationship of S1, S2, and L. Therefore, it can be seen that the conditions of S1>L>S2 are desirable as in Examples 1, 2, and 3, and that the effect of the agitation promoting holes is insufficient under the conditions of L>S1>S2 as in Comparative Example 2. . With the above configuration of the present invention, it is possible to suppress scumming caused by toner replenishment without using an additional member such as a stirring screw.

[Embodiment 2]
In this embodiment, in the axial direction of the stirring shaft 24, when the length of the sheet member 25 is set to 1, the ratio defined by the length of the stirring promotion hole/the length of the sheet member is set to 0.2 or less. . An example of how to solve image density unevenness caused by toner supply unevenness in a low-temperature, low-humidity environment by defining it in this way will be shown. Detailed explanation of the points that overlap with Embodiment 1 other than this point will be omitted.
By providing the agitation promotion holes 26 in the sheet member 25 of the agitation member 22 under the same conditions as described in the first embodiment, the supplied toner 80a and the existing toner 80b in the toner storage chamber can be sufficiently mixed. However, on the other hand, if the agitation promoting holes are large in the longitudinal direction, which is a direction parallel to the axial direction of the agitation shaft 24, the way the sheet member 25 bends changes, which may change the toner conveyance force. Particularly, for example, when toner electrostatically aggregates in a low-temperature, low-humidity environment and fluidity decreases, or when high-print printing is performed continuously, uneven image density may occur due to uneven toner supply in the longitudinal direction.
Below, the effect when the size of the agitation promotion hole in the transverse direction, which is a direction perpendicular to the longitudinal direction, is fixed and the size in the longitudinal direction is changed will be explained.

[Effect confirmation experiment]
An effect confirmation experiment was conducted in a low temperature, low humidity environment (temperature 15°C, humidity 10%), and scumming and image density unevenness were confirmed. The results are shown in Table 2.

〇Evaluation of image density unevenness The image density unevenness here refers to image defects such as slight white spots that occur because the necessary amount of toner is not supplied to the developing roller when high print is continuously viewed.
After printing 1000 sheets at a printing rate of 1%, a solid black image was printed, and the image density at that time was measured using a "Macbeth reflection densitometer RD918" (manufactured by Macbeth). Evaluation was performed based on the following criteria.
○: The difference in density between the black part and the white part is 0.1 or less.
Δ: The difference in density between black and white areas is 0.1 to less than 0.2.
×: The density difference between the black part and the white part is 0.2 or more.

The ratio shown in Table 2 is defined as the length of the agitation promoting hole/the length of the sheet member, and indicates the toner supplying ability of the sheet member 25. The lower the ratio is, the smaller the agitation promoting holes are, making it easier to transport the toner, resulting in a larger toner supply capacity. In the case of Examples 1, 4, and 5, the agitation promoting holes were effective in suppressing background smearing, and unevenness in image density did not occur. However, as in Example 6, when the length of the agitation promotion hole in the longitudinal direction is further increased from that in Example 1, uneven supply of toner to the developing chamber tends to become apparent as uneven image density. In the case of Comparative Example 3, the length of the agitation promotion hole in the longitudinal direction is 60 mm, and while it shows a certain effect on background smearing, image defects occur when solid images are printed continuously. Oops. To summarize the above, the length of the agitation promoting hole in the longitudinal direction is preferably within a range that does not cause unevenness in the amount of toner supplied to the developing chamber, and the ratio needs to be 0.2 or less. From the above, it is possible to confirm the appropriate size of the stirring promotion hole in the longitudinal direction, and it is possible to solve image density unevenness in a low temperature and low humidity environment without using a stirring screw.

[Embodiment 3]
This embodiment differs from Embodiment 1 in the configuration of the stirring member. In this embodiment, an example will be shown in which the number of sheet members of the stirring member is increased to two to achieve improvements in toner supply ability and stirring ability, which were difficult to achieve when using only one sheet member. When the sheet member 25 of the stirring member 22 described in Embodiment 1 is the first sheet member 25a, a second sheet member 25b, which is different from the first sheet member 25a, is attached to the stirring shaft 24, which is the same rotating shaft portion as the stirring member 22. It is fixed and placed in the toner storage chamber 18 so as to be in contact with the inner wall surface of the toner storage chamber 18 . Note that the position of the second sheet member 25b fixed to the stirring shaft 24 is different from that of the first sheet member 25a in the circumferential direction of the stirring shaft 24. Detailed explanation of the points that overlap with Embodiment 1 other than this point will be omitted.
FIG. 9 is a schematic sectional view of the process cartridge 7 of this embodiment, and FIG. 10 is a schematic sectional view of the developing device. The features of this embodiment will be explained in detail using these.
The difference between the stirring member of this embodiment and the first embodiment is that two sheets are provided, a first sheet member 25a and a second sheet member 25b. This is more preferable because it can improve the toner supply ability of the printer. For example, even if the stirring capacity per sheet and the toner supply capacity to the supply roller 20 are reduced by reducing the thickness of the stirring sheet, the stirring sheet will still slide on the wall surface while maintaining its stirring capacity and supply capacity as a stirring member. This is more preferable because it can also reduce the sound of rubbing.

As shown in FIG. 11, the stirring member of this embodiment has a sheet member added to that of the first embodiment. Specifically, the sheet member of the stirring member 22 in Embodiment 1 is the first sheet member 25a, and the second sheet member 25b without stirring promotion holes is the same as the stirring shaft to which the first sheet member 25a is fixed. They are fixed at different positions in the circumferential direction and arranged so as to be able to contact the inner wall surface of the toner storage chamber 18 . As a result, the first sheet member 25a having the agitation promoting hole efficiently mixes the toner 80a replenished as described in Embodiment 1 and the toner 80b in the toner storage chamber, and supplies the mixed toner. It can be supplied to the roller 20. Furthermore, if the positional relationship between the sheet member and the agitation promoting holes is the same as in the first embodiment, the same effects as in the first embodiment can be obtained. That is, if we pay attention to the movement of the first sheet member 25a, it is the same as in the first embodiment, so the same effects as in the first embodiment can be obtained. Furthermore, if we pay attention to the movement of the second sheet member 25b, the flow of toner that has passed through the agitation promotion holes of the first sheet member 25a and the flow of toner carried by the second sheet member 25b collide, so that new and old toner are mixed. Here too, the same effects as in the first embodiment can be obtained.

For example, as a modification of this embodiment, there is also a configuration as shown in FIG. 12, in which the first sheet member 25a and the second sheet member 25b each have a structure in which two sheets are overlapped in the thickness direction. The first sheet member 25a has a two-layer structure of the first sheet part 25a-1 and the second sheet part 25a-2, and the second sheet member 25b has a two-layer structure of the first sheet part 25b-1 and the second sheet part 25b- It has a two-layer structure. The lengths (free lengths) from the fixed ends fixed to the stirring shaft 22 to the free ends of the first sheet parts 25a-1 and 25b-1 are longer than those of the second sheet parts 25a-2 and 25b-2, respectively. It's getting longer. Therefore, when rotating in the storage chamber, the tips (free ends) of the first sheet parts 25a-1 and 25b-1 can come into contact with the inner wall surface of the toner storage chamber 18, but the second sheet parts 25a-2 and 25b-2 The tip (free end) does not come into contact with the inner wall surface of the toner storage chamber 18 . Note that, as shown in FIG. 12, when rotating, the first sheet portions 25a-1 and 25b-1 of the first sheet member 25a and the second sheet member 25b are located on the downstream side in the rotation direction, and on the second sheet portion. 25a-2 and 25b-2 are arranged on the upstream side in the rotation direction. Further, the first sheet member 25a and the second sheet member 25b are provided with stirring promotion holes 26a and 26b at the center in the longitudinal direction of the sheet members, as in the first embodiment, and the axis of the stirring shaft in each sheet member is It is arranged at a position overlapping with the supply port 23 in the direction. In this way, by forming the first sheet member 25a and the second sheet member 25b into stacked sheets, the tip (free end) side of the sheet member that contacts the inner wall surface of the toner storage chamber 18 and the agitation The flexibility of the sheet member can be made different depending on the fixed end fixed to the shaft. In other words, the stirring shaft side of the first sheet member 25a and the second sheet member 25b is less likely to deform, so that the stirring ability can be further improved. Furthermore, since the stirring promoting holes are provided in each of the first sheet member 25a and the second sheet member 25b, the effect of the stirring promoting holes can be further obtained.

As described above, by increasing the number of sheet members of the stirring member to two, it is possible to achieve improvements in the toner supply ability and stirring ability, which were difficult to achieve when the number of sheet members was one. Note that in this embodiment, the number of sheet members is two, but it is not limited to this. That is, if the configuration includes one or more sheet members fixed to the same stirring shaft, it is possible to obtain effects such as improved toner supply ability and stirring ability.

[Embodiment 4]
In this embodiment, the configuration of the stirring member is partially different from the modification of Embodiment 3. In this embodiment, an example is shown in which flexible sheet members are arranged in a double layered manner and agitation promoting holes are provided only in one of the sheet members, thereby improving the agitation ability compared to Embodiment 3.
FIG. 13 is a schematic sectional view of the process cartridge 7 of this embodiment, and FIG. 14 is a schematic sectional view of the developing device of this embodiment. FIG. 15 is a conceptual diagram of the stirring member according to this embodiment. The features of this embodiment will be explained in detail using these.
Regarding the stirring member of this embodiment, if the sheet member 25c is the first sheet member and the sheet member 25d is the second sheet member, flexible sheet members are arranged in a double layer on each sheet member. This is the same as the modification of the third embodiment. That is, the first sheet member 25c has a two-layer structure of the first sheet portion 25c-1 and the second sheet portion 25c-2, and the second sheet member 25d has a two-layer structure of the first sheet portion 25d-1 and the second sheet portion. It has a two-layer structure of 25d-2. The lengths (free lengths) from the fixed ends fixed to the stirring shaft 22 to the free ends of the first sheet parts 25c-1 and 25d-1 are longer than those of the second sheet parts 25c-2 and 25d-2, respectively. It's getting longer. Therefore, when rotating in the storage chamber, the tips (free ends) of the first sheet portions 25c-1 and 25d-1 can come into contact with the inner wall surface of the toner storage chamber 18, but the second sheet portions 25c-2 and 25d-2 can contact the inner wall surface of the toner storage chamber 18. The tip (free end) does not come into contact with the inner wall surface of the toner storage chamber 18 . Note that, as shown in FIGS. 13 to 15, the first sheet portions 25c-1 and 25d-1 of the first sheet member 25c and the second sheet member 25d are arranged on the downstream side in the rotation direction when rotating. ing. On the other hand, the second seat portions 25c-2 and 25d-2 are arranged on the upstream side in the rotation direction.

In this embodiment, points different from Embodiment 3 will be explained using FIGS. 13 to 15. The difference from the third embodiment is that stirring promotion holes 26d are provided only in the second sheet member 25d. Similar to Embodiments 1 and 3, the second sheet member 25d is provided with an agitation promoting hole 26d, which is a through hole penetrating in the thickness direction, at the center in the longitudinal direction of the sheet member. It is arranged at a position overlapping with the supply port 23 in the axial direction.
In this way, each of the two sheet members is constructed in a double layered manner, and only one of the sheet members 25d is provided with stirring promoting holes. The advantages of configuring the stirring member in this way will be explained. As shown in FIGS. 13 to 15, by doubling the sheet member, the sheet member is flexible at the tip side that contacts the inner wall surface of the toner storage chamber 18 and at the side fixed to the stirring shaft. You can change your gender to different states. In other words, since the stirring shaft side of the sheet member is less likely to deform, the stirring ability can be further improved. Furthermore, by providing the agitation promoting holes 26d only in the second sheet member 25d, compared to the third embodiment, the supplied toner and the toner in the toner storage chamber are mixed efficiently while placing more emphasis on the toner conveying ability. Then, the mixed toner can be supplied to the supply roller 20. Further, if the positional relationship between the sheet member of the stirring member and the stirring promotion hole is the same as that in the first embodiment, the same effects as in the first embodiment can be obtained. This mechanism is as described in the third embodiment.
Further, for example, by reducing the sheet thickness of the sheet member 25c of the stirring member, it is possible to reduce the sound of the sheet member rubbing against the wall surface while maintaining the stirring ability and supply ability of the stirring member.

Furthermore, as shown in FIG. 16 as a modified example of the present embodiment, the length of the second sheet portion 25d-2 stacked on the second sheet member 25d in the transverse direction is the first sheet member 25c without the agitation promoting hole. The second sheet portion 25c-2 may be shorter than the second sheet portion 25c-2, and may be overlapped only on the stirring shaft side. In such a case, the same effect can be obtained if the stirring promotion holes 26d formed in the second sheet member 25d are formed as through holes as stirring promotion holes only in the first of the stacked sheet members. .

[Other embodiments]
The effect of sufficiently mixing toner described in Embodiments 1 to 4 is not limited to the pumping method of supplying toner to the developing roller 17 located above the toner storage chamber as described above. That is, a self-gravity system in which the developing roller 17 is provided at substantially the same height as the toner storage chamber 18 or located below the toner storage chamber 18 is also possible. For example, a configuration as shown in FIG. 17 may be used. Even in such a configuration, the new toner replenished into the toner storage chamber 18 tends to accumulate near the replenishment port. The toner can be mixed efficiently.

To summarize the present invention as described above, in Embodiment 1, in order to suppress background smearing due to toner replenishment, the size of the agitation promotion hole in the width direction and the positional relationship between the agitation promotion hole and the replenishment port are set to S1>L>S2. It was solved. In Embodiment 2, in order to suppress unevenness in image density caused by uneven toner supply in a low-temperature, low-humidity environment, the ratio defined by the length in the longitudinal direction of the stirring promotion hole/the length in the longitudinal direction of the sheet member is set to 0.2. I solved it by doing the following. In Embodiments 3 and 4, the stirring ability and toner supplying ability of the stirring member are improved while maintaining the scumming suppressing effect of the stirring promotion holes, or the sound of the stirring member rubbing against the wall surface is reduced, etc. The configuration to enable this is shown.

4... Developing unit, 16... Developing frame, 22... Stirring member, 24... Stirring shaft, 25... Sheet member, 26... Stirring promotion hole, 23... Supply port

Claims (11)

a frame body including a storage chamber for storing developer and a replenishment port for replenishing the developer into the storage chamber from the outside;
The sheet member includes a rotating shaft rotatably supported by the frame, and a seat member having one end fixed to the rotating shaft and the other end being a free end and rotatable in accordance with the rotational movement of the rotating shaft. and a stirring member that stirs the developer in the storage chamber;
A developing device comprising:
The free end of the sheet member is capable of contacting the inner wall surface of the storage chamber in which the replenishment port is formed, and in a region of the sheet member that is capable of contacting the inner wall surface of the storage chamber. A through hole is provided that penetrates the sheet member in the thickness direction ,
The through hole is
When viewed from the axial direction of the rotating shaft portion,
The position where the sheet member is fixed to the rotating shaft portion is defined as position A,
The distance between position A and the center position of the replenishment port in the rotational direction of the rotating shaft portion is L,
In the sheet member, the length from position A to one end of the through hole closer to the free end of the sheet member is S1,
When the length from position A in the sheet member to the other end of the through hole of the sheet member closer to the rotating shaft portion is S2,
S1>L>S2
A developing device , characterized in that it is provided on the sheet member so that the developing device has the following characteristics. 2. The developing device according to claim 1, wherein the through hole is arranged at a position that overlaps a position where the replenishment port is provided in the axial direction of the rotating shaft portion. 3. The developing device according to claim 1, wherein a ratio of the length of the through hole to the length of the sheet member in the axial direction of the rotating shaft portion is 0.2 or less. The sheet member includes a first sheet member and a second sheet member,
4. The developing device according to claim 1, wherein the first sheet member and the second sheet member are attached to different positions in the circumferential direction of the rotating shaft portion. 5. The developing device according to claim 4 , wherein the through hole is provided in the first sheet member and the second sheet member. The first sheet member and/or the second sheet member is characterized in that it has a first sheet portion and a second sheet portion that are attached to the rotating shaft portion in an overlapping state in the thickness direction. The developing device according to claim 4 or 5 . In the rotational direction of the rotating shaft, the first seat part is located on the downstream side, and the second seat part is located on the upstream side,
The free length of the first seat part from the fixed end fixed to the rotating shaft part to the free end is longer than the free length of the second seat part, and the free end of the second seat part is the free end of the first sheet portion is capable of contacting the inner wall surface without contacting the inner wall surface;
7. The developing device according to claim 6 . The frame body is provided above the storage chamber in the direction of gravity in a posture during use, and includes a development chamber in which a developer carrier carrying developer is arranged;
The developing device according to any one of claims 1 to 7 , wherein the developer contained in the storage chamber is transported to the developing chamber by the stirring member. 9. The developing device according to claim 8 , wherein the developing chamber further includes a supply member that supplies developer to the developer carrier. The developing device according to any one of claims 1 to 9 ,
an image carrier carrying a developer image;
A cartridge characterized in that it is removably attachable to the main body of an image forming apparatus. At least one of the developing device according to any one of claims 1 to 9 or the cartridge according to claim 10 ,
A transfer member;
An image forming apparatus comprising:

Images