JP2024050938A - Developing device, process cartridge and image forming apparatus - Google Patents

Abstract

[Problem] To provide a developing device, process cartridge, and image forming apparatus that realize a configuration capable of supplying developer from below to above, and improves the mixing of existing developer with newly replenished developer from a replenishing port in a developer storage chamber. [Solution] The developer storage chamber is provided with a replenishing port for replenishing developer from the outside to the developer storage chamber, and when viewed along the rotation axis of the rotating shaft in a position during use, with a perpendicular line passing through the rotation center of the rotating shaft as a reference, at least a part of the communication port and at least a part of the replenishing port are both located on one side of the perpendicular line, and a restoration portion is located on the other side of the perpendicular line. [Selected Figure] Figure 6

Description

The present invention relates to a developing device, a process cartridge, and an image forming apparatus. In particular, the present invention relates to an electrophotographic image forming apparatus that employs an electrophotographic system, and a developing device and a process cartridge used in the electrophotographic image forming apparatus.

Conventionally, it is widely known that a developing cartridge (including a developing means) or a process cartridge (including a developing means and a photosensitive drum) can be attached to and detached from the main body of an electrophotographic image forming apparatus.

Among them, there are cartridges such as that described in Patent Document 1, which transport developer by flying it from a lower developer storage chamber through a communication port to an upper developing chamber by using the elastic deformation (elastic restoring force) of an agitating sheet.

On the other hand, in order to improve image formation efficiency, a technology is being considered in which a supply port is provided in the developer storage chamber of a cartridge as in Patent Document 1, and developer is directly supplied from the outside to the developer storage chamber through the supply port.

Patent Publication 2011-253203

However, in the cartridge described in Patent Document 1, if a supply port is provided in the developer storage chamber, the developer newly supplied to the developer storage chamber from the supply port may not be mixed sufficiently with the existing toner and may be transported to the upper developing chamber via the communication port. This may reduce the stability of the formed image.

The present invention aims to provide a developing device, process cartridge, and image forming device that realizes a configuration that allows developer to be supplied from below to above, and improves the mixing of newly replenished developer from a supply port in a developer storage chamber with existing developer.

The developing device of the present invention comprises:
a developing frame including a developing chamber in which a developer carrier that carries a developer is accommodated, a developer accommodating chamber that is located below the developing chamber in an orientation during use and accommodates the developer, and a communication port that communicates the developing chamber with the developer accommodating chamber;
a transport member provided in the developer storage chamber and configured to transport the developer stored in the developer storage chamber to the developing chamber, the transport member including a rotatable shaft portion and a sheet portion having one end fixed to the shaft portion and the other end being a free end and capable of elastic deformation;
a deformation portion that is provided in the developer accommodating chamber and that comes into contact with the free end of the sheet portion that rotates in accordance with the rotation of the rotation shaft portion, thereby bending and elastically deforming the sheet portion;
a restoring portion that is provided in the developer accommodating chamber at a position upstream of the communication port and downstream of the deformation portion in a rotation direction of the rotating shaft portion, and that releases and restores the sheet portion that has been elastically deformed by the deformation portion, thereby causing the developer carried on the sheet portion to fly toward the communication port;
A developing device having
the developer storage chamber is provided with a supply port for supplying developer from the outside to the developer storage chamber,
When viewed along the rotation axis direction of the rotating shaft portion in a posture during use, when a perpendicular line passing through the rotation center of the rotating shaft portion is used as a reference,
At least a portion of the communication port and at least a portion of the supply port are both located on one side of the perpendicular line,
The restoring portion is located on the other side of the perpendicular line.

The process cartridge of the present invention is characterized in that it is equipped with an image carrier that carries a developer image and the developing device, and is detachable from the image forming device.

The image forming apparatus of the present invention is also characterized by comprising at least one of the developing device or the process cartridge, and a transfer member.

This invention realizes a configuration that allows developer to be supplied from a lower developer storage chamber to an upper developer storage chamber, and improves the mixing of the existing developer with the newly replenished developer in the developer storage chamber through the supply port.

1 is a schematic cross-sectional view of an image forming apparatus according to an embodiment of the present invention; FIG. 1 is a schematic cross-sectional view of a process cartridge used in an image forming apparatus according to an embodiment of the present invention; FIG. 1 is a schematic perspective view of a process cartridge according to an embodiment of the present invention, viewed from above on the driving side; FIG. 1 is a schematic perspective view of a developing unit used in an image forming apparatus according to an embodiment of the present invention, viewed from above on the drive side; (a) is a conceptual diagram showing the toner stirring state in the developing unit according to the embodiment of the present invention; (b) is a conceptual diagram showing the free length L (free state) of the sheet member of the stirring member; FIG. 1 is a conceptual diagram showing areas A and B in a development unit according to an embodiment of the present invention. (a) is a conceptual diagram showing the attitude of a developing unit and the position of a supply port in an embodiment of the present invention; (b) to (d) are conceptual diagrams showing the attitude of a developing unit and the position of a supply port in comparative examples compared to the embodiment of the present invention. FIG. 1 is a conceptual diagram showing the circulation of toner in a developing unit according to an embodiment of the present invention.

The present invention can be implemented in the form of either an electrophotographic image forming apparatus (hereinafter sometimes simply referred to as an "image forming apparatus"), or a process cartridge or developing device that constitutes part of an image forming apparatus.

The image forming device according to the present invention will be described below with reference to the drawings.

The examples described below are illustrative of the present invention, and unless otherwise specified, the dimensions, materials, shapes, and relative positions of the components described below do not limit the scope of the present invention.

Here, an electrophotographic image forming apparatus is one that forms an image on a recording medium using an electrophotographic image forming method. Examples of electrophotographic image forming apparatuses include electrophotographic copying machines, electrophotographic printers (e.g., laser beam printers, LED printers, etc.), facsimile machines, and word processors.

The developing device used in the image forming apparatus has at least a developing means. The developing device is made into a cartridge and can be attached to and detached from the main body of the electrophotographic image forming apparatus. The developing device may also include a toner cartridge that can be attached to and detached from the frame of the developing device and can supply toner to the developing device.

In addition, a process cartridge constituting a part of an image forming apparatus is a cartridge in which a charging means, a developing means or a cleaning means and an electrophotographic photosensitive drum are integrated into one cartridge, and this cartridge is detachable from the main body of an electrophotographic image forming apparatus. In addition, at least one of a charging means, a developing means and a cleaning means and an electrophotographic photosensitive drum are integrated into one cartridge, and this cartridge is detachable from the main body of an electrophotographic image forming apparatus. In addition, at least a developing means and an electrophotographic photosensitive drum are integrated into one cartridge, and this cartridge is detachable from the main body of an electrophotographic image forming apparatus. In addition, a process cartridge can be fixed to an image forming apparatus for use.

The image forming apparatus and process cartridge according to the present invention will be described below with reference to the drawings.

<Overall Configuration of Image Forming Apparatus>
First, the overall configuration of an electrophotographic image forming apparatus 100 (hereinafter simply referred to as an image forming apparatus) will be described with reference to FIG.

Figure 1 is a cross-sectional conceptual diagram of an image forming apparatus according to an embodiment of the present invention.

As shown in FIG. 1, four removable process cartridges 70 (70Y, 70M, 70C, 70K) are mounted using mounting members (not shown). The upstream side of the process cartridges 70 in the mounting direction of the image forming device 100 is defined as the front side, and the downstream side of the mounting direction is defined as the rear side.

Each process cartridge 70 includes a photosensitive drum 1 (1a-1d), a charging roller 2 (2a-2d) around the photosensitive drum 1 (image carrier), a developing roller 25 (25a-25d), a cleaning member 6 (6a-6d), and other process means that are integrally arranged.

The charging roller 2 uniformly charges the surface of the photosensitive drum 1, and the developing roller 25 (developer carrier) develops the latent image formed on the photosensitive drum 1 with toner (hereinafter sometimes referred to as developer) to make it visible. The cleaning member 6 removes any developer remaining on the photosensitive drum 1 after the toner image formed on the photosensitive drum 1 is transferred to a recording medium.

In addition, below the process cartridge 70, a scanner unit 3 is provided for selectively exposing the photosensitive drum 1 based on image information and forming a latent image on the photosensitive drum 1.

A cassette 17 containing a recording medium S is attached to the bottom of the device body 100A of the image forming device 100. A recording medium transport means is provided so that the recording medium S passes through the secondary transfer roller 69 and the fixing unit 74 and is transported to the top of the device body 100A.

That is, there is a feed roller 54 that separates and feeds the recording media S in the cassette 17 one by one, a pair of transport rollers 76 that transport the fed recording media S, and a pair of registration rollers 55 that synchronize the latent image formed on the photosensitive drum 1 with the recording media S.

In addition, an intermediate transfer unit 5 is provided above the process cartridges 70 (70Y, 70M, 70C, 70K) as an intermediate transfer means for transferring the toner images formed on each photosensitive drum 1 (1a to 1d).

The intermediate transfer unit 5 has a drive roller 56, a driven roller 57, primary transfer rollers 58 (58a to 58d) facing the photosensitive drums 1 of each color, and an opposing roller 59 facing the secondary transfer roller 69, across which the transfer belt 50 is stretched.

The transfer belt 50 then moves in a circular motion so as to face and come into contact with all of the photosensitive drums 1, and primary transfer is performed from the photosensitive drums 1 onto the transfer belt 50 by applying a voltage to the primary transfer roller 58 (transfer member). The toner on the transfer belt 50 is transferred to the recording medium S by applying a voltage to the opposing roller 59 and secondary transfer roller 69 arranged inside the transfer belt 50.

When forming an image, each photosensitive drum 1 is rotated, and the photosensitive drum 1, which is uniformly charged by the charging roller 2, is selectively exposed to light from the scanner unit 3. This forms an electrostatic latent image on the photosensitive drum 1.

The electrostatic latent image is then developed by the developing roller 25 to form a toner image of each color on each photosensitive drum 1. In synchronization with this image formation, the registration roller pair 55 transports the recording medium S to the secondary transfer position where the opposing roller 59 and the secondary transfer roller 69 are in contact with each other with the transfer belt 50 interposed therebetween.

Then, a transfer bias voltage is applied to the secondary transfer roller 69, which secondarily transfers each color toner image on the transfer belt 50 to the recording medium S. This forms a color image on the recording medium S.

The recording medium S on which the color image has been formed is heated and pressurized by the fixing unit 74 to fix the toner image. The recording medium S is then discharged to the discharge unit 75 by the discharge rollers 72. The fixing unit 74 is located at the top of the device main body 100A.

The first to fourth toner cartridges 9 are arranged horizontally below the process cartridge 70 in an order corresponding to the color of toner contained in each process cartridge 70.

That is, the first toner cartridge 9Y contains yellow (Y) toner, the second toner cartridge 9M contains magenta (M), the third toner cartridge 9C contains cyan (C), and the fourth toner cartridge 9K contains black (K) toner. Each toner cartridge 9 supplies toner to the process cartridge 70 that contains toner of the same color.

The toner cartridge 9 is replenished when a remaining amount detection unit (not shown) provided in the device main body 100A of the image forming device 100 detects that the remaining amount of toner in the process cartridge 70 is insufficient. The toner cartridge 9 is detachably attached to the image forming device 100 via attachment means such as an attachment guide (not shown) and a positioning member (not shown) provided in the image forming device 100. The process cartridge 70 and the toner cartridge 9 will be described in detail later.

Below the toner cartridges 9, first to fourth toner transport devices 18 are arranged corresponding to each toner cartridge 9. Each toner transport device 18 transports the toner received from each toner cartridge 9 upward and supplies the toner to each development unit 4 (development device).

<Process cartridge>
Next, a process cartridge 70 embodying the present invention will be described with reference to FIG.

Figure 2 is a schematic cross-sectional view of a process cartridge used in an image forming apparatus according to an embodiment of the present invention.

Specifically, FIG. 2 shows the main cross section of a process cartridge 70 containing toner. Note that cartridge 70Y containing yellow toner, cartridge 70M containing magenta toner, cartridge 70C containing cyan toner, and cartridge 70K containing black toner all have the same configuration.

The process cartridge 70 (70Y, 70M, 70C, 70K) has a cleaning unit 26 (26a-26d) and a developing unit 4 (4a-4d). The cleaning unit 26 has a photosensitive drum 1 (1a-1d), a charging roller 2 (2a-2d), and a cleaning member 6 (6a-6d). And the developing unit 4 (developing device) has a developing roller 25.

As mentioned above, the charging roller 2 and cleaning member 6 are arranged around the photosensitive drum 1. The cleaning member 6 is composed of an elastic member 7 made of a rubber blade and a cleaning support member 8.

The tip 7a of the rubber blade 7 is disposed in contact with the photosensitive drum 1 in the counter direction to the rotation direction of the photosensitive drum 1. Residual toner removed from the surface of the photosensitive drum 1 by the cleaning member 6 falls into the removed toner chamber 27a.

In addition, a scoop sheet 21 that prevents the removed toner from the removed toner chamber 27a from leaking is in contact with the photosensitive drum 1. The driving force of the main body drive motor (not shown), which serves as the driving source, is transmitted to the cleaning unit 26, thereby rotating the photosensitive drum 1 in response to the image formation operation.

The charging roller 2 is rotatably attached to the cleaning unit 26 via the charging roller bearing 28, and is pressed toward the photosensitive drum 1 by the charging roller pressure member 46, and rotates in response to the rotation of the photosensitive drum 1.

<Developing Unit and Toner Transport Means>
Next, the developing unit and the toner transport means will be described with reference to FIGS.

Figure 3 is a conceptual perspective view of the process cartridge of an embodiment of the present invention, viewed from above on the drive side.

Figure 4 is a conceptual perspective view of the development unit used in an image forming apparatus according to an embodiment of the present invention, viewed from above on the drive side.

Figure 5(a) is a conceptual diagram showing the toner stirring state in the development unit of an embodiment of the present invention. Figure 5(b) is a conceptual diagram showing the free length L (free state) of the sheet member of the stirring member.

As shown in Figures 2 and 3, the developing unit 4 is composed of a developing roller 25 that rotates in contact with the photosensitive drum 1, and a developing frame 31 that supports the developing roller 25.

The developing roller 25 is rotatably supported by the developing frame 31 via the developing front bearing 12 and the developing rear bearing 13, which are attached to both sides of the developing frame 31 (see FIG. 4). In addition, on the circumference of the developing roller 25, there are arranged a toner supply roller 34 (supply member) that contacts the developing roller 25 and rotates in the direction of arrow C, and a developing blade 35 for regulating the toner layer on the developing roller 25.

When the toner supplied from the toner supply roller 34 to the developing roller 25 passes through the developing blade 35, the toner regulates the amount of toner coat on the developing roller 25 and the toner is charged. This forms a toner coat that is optimal for developing the latent image created on the photosensitive drum.

The developing roller 4 and the photosensitive drum 1 rotate so that their surfaces move in the same direction (from bottom to top in this embodiment) at the opposing portion (contact portion). In this embodiment, the toner that is negatively charged by frictional charging in response to a predetermined DC bias applied to the developing roller 17 transfers only to the bright potential portion due to the potential difference at the developing portion that contacts the photosensitive drum 1, thereby visualizing the electrostatic latent image.

In addition, a blow-out prevention sheet 20 is provided as a development contact sheet to prevent toner from leaking from the development frame 31 that is in contact with the development roller 25. Furthermore, the toner storage chamber 31a (developer storage chamber) of the development frame 31 is provided with a toner transport member 36 (transport member) for stirring the stored toner and transporting the toner to the toner supply roller 34.

As shown in FIG. 5(a), the toner transport member 36 is composed of an agitator shaft 36a (rotating shaft portion) that can be rotated by an external driving force, and a sheet member 36b (sheet portion) that is attached to the agitator shaft 36a and rotates together with the agitator shaft 36a.

Next, we will explain the toner transport in the development unit. The toner storage chamber 31a is provided with a deformation portion 31a1 that abuts against the sheet member 36b below the opening 31c (communication port). As the sheet member 36b rotates, it abuts against the deformation portion 31a1.

As a result, sheet member 36b receives a force from deformation portion 31a1. As a result, sheet member 36b deforms against the elastic force of sheet member 36b. Furthermore, sheet member 36b rotates in contact with deformation portion 31a1, and carries toner on its surface downstream of the rotation, transporting it. In this embodiment, deformation portion 31a1 refers to the portion of the inner wall of the toner storage chamber up to where sheet member 36b leaves it, as shown in FIG. 5(a).

The toner storage chamber 31a is provided with a restoration portion 31a2 downstream of the deformation portion 31a1 and upstream of the opening 31c during the rotation of the sheet member 36b. Here, the restoration portion 31a2 is a portion for releasing the contact between the sheet member 36b and the inner wall of the toner storage chamber 31a. In this embodiment, the restoration portion 31a2 is located above a horizontal plane that includes the rotation axis of the stirring member.

Therefore, after the tip of the free end side of the sheet member 36b passes through the deformation section 31a1 as the sheet member 36b rotates, the contact with the inner wall of the sheet member 36b is released at the restoration section 31a2. Then, the sheet member 36b is released from the state in which it was deformed by the deformation section 31a1, and returns to its natural state (original shape) by its own elastic restoring force.

This change in shape of the sheet member 36b in the restoration direction causes the toner carried and transported on the sheet member 36b to fly against gravity toward the opening 31c. This opening 31c is located downstream of the restoration portion 31a2 in the rotation direction of the sheet member 36b.

Some of the toner that flies toward the opening 31c is transported into the developing chamber 31b. On the other hand, the toner that does not reach the developing chamber 31b falls into the toner storage chamber 31a and remains at the bottom of the toner storage chamber 31a, returning to its original state. By repeating this cycle, the toner is agitated and transported.

<Toner Supply Operation>
Next, the toner supplying operation in this embodiment will be described.

As shown in FIG. 4, the developing unit 4 has an inlet 40 at one end downstream in the attachment/detachment direction. An inlet/transport path 41 is provided in communication with the toner inlet 40, and an inlet/transport screw (not shown) is disposed inside. The inlet/transport path 41 extends parallel to the rotational axis direction of the developing roller 25 and the supply roller 34.

Furthermore, a storage chamber communication port 43 (supply port) for supplying toner to the toner storage chamber 31a is provided near the longitudinal center of the development unit 4, and connects the receiving and transporting path 41 with the toner storage chamber 16b. The toner discharged from the toner cartridge 9 reaches the toner receiving port 40 by the toner transport device 18 attached to the device main body 100A. The toner received from the toner receiving port 40 is transported and replenished into the toner storage chamber 16b via the storage chamber communication port 43.

More specifically, as described above, the developing unit 4 in this embodiment is equipped with a developing frame 31.

The developing frame 31 has a developing chamber 31b that houses the developing roller 25 that carries the toner, a toner storage chamber 31a that is located below the developing chamber when in the in-use position and that stores the toner, and an opening 31c that connects the developing chamber to the toner storage chamber.

The toner storage chamber 31a is provided with a toner transport member 36 that transports the toner stored in the toner storage chamber to the developing chamber 31b.

The toner transport member 36 includes a rotatable stirring shaft 36a and an elastically deformable sheet member 36b. One end 36b1 of the sheet member 36b is fixed to the stirring shaft 36a, and the other end 36b2 is a free end.

The toner storage chamber 31a is provided with a deformation portion 31a1.

When the free end (36b2) of the sheet member 36b, which rotates in conjunction with the rotation of the agitator shaft 36a, comes into contact with the deformation portion 31a1, the sheet member is deflected and elastically deformed.

The toner storage chamber 31a is provided with a restoration section 31a2 located upstream of the opening 31c and downstream of the deformation section 31a1 in the rotation direction X2 of the agitation shaft 36a.

The sheet member 36b (free end) in a state elastically deformed by the deformation portion 31a1 is released by the restoration portion 31a2 and elastically restored. As a result, the toner carried on the upper surface of the sheet member 36b is caused to fly toward the opening 31c and is supplied to the developing chamber 31b.

The toner storage chamber 31a is provided with a storage chamber communication port 43 for replenishing toner from the outside to the toner storage chamber 31a.

<Mixing of toner inside the toner storage chamber>
Toner is replenished from the toner cartridge 9 into the toner storage chamber 31a via the toner transport device 18 and the storage chamber communication port 43. The replenished toner (hereinafter referred to as "new toner"), together with the toner that was already in the toner storage chamber 31a before the replenishment (hereinafter referred to as "old toner"), is stirred (mixed) and transported inside the toner storage chamber 31a by the rotation of the sheet member 36b.

As the development unit 4 is used and toner circulation is repeated within the development unit 4, the old toner in the toner storage chamber 31a deteriorates. Deterioration here refers to phenomena such as the toner resin being worn down and deformed by mechanical friction, and external additives added to the surface becoming detached or embedded within the resin, causing the charging characteristics and other behavior to change compared to new toner replenished from the toner refill container.

In other words, as the development unit 4 is used and the old toner deteriorates, a difference in charging characteristics occurs between the old toner and the new toner. If the charging characteristics of the toner differ, when visualizing the electrostatic latent image formed on the photosensitive drum 1, the amount of toner filling the electrostatic latent image may change, and the toner may fly to the dark potential as well as the light potential. This results in image defects such as "uneven density" and "fogging," which will be described later.

To prevent such problems from occurring, it is important to thoroughly mix the new toner and old toner in the toner storage chamber 31a even if a difference in charging characteristics occurs between the new toner and old toner, and to reduce the uneven distribution of the new toner among the old toner.

In the present invention, the position of the opening 31c, the restoration portion 31a2, and the position of the storage chamber communication port 43 are specified as described below, thereby solving the problem with a simple configuration without the need for additional components or complex configuration.

Next, we will explain in detail the relationship between the positions of the opening 31c, the restoration section 31a2, the position of the storage chamber communication opening 43, and the occurrence of problems.

Figure 6 is a conceptual diagram showing areas A and B within a development unit in an embodiment of the present invention.

Figure 7(a) is a conceptual diagram showing the attitude of the development unit and the position of the supply port in an embodiment of the present invention. Figures 7(b-d) are conceptual diagrams showing the attitude of the development unit and the position of the supply port in a comparative example compared to the embodiment of the present invention.

First, as shown in Figure 6, when the device is in the position during use, a perpendicular line is drawn through the center of the agitator shaft 36a to divide the device into two parts, left and right. The area that includes the restoration portion 31a2 is called area A, and the side that does not include the restoration portion 31a2 is called area B.

In this case, the combination of the positions of the opening 31c and the storage chamber communication port 43 can be classified into four patterns shown in Table 1 and (a) to (d) of Figure 7. Note that if the opening 31c and the storage chamber communication port 43 are present between areas A and B, even if they are partially within area B, they are considered to be area B.

First, in this embodiment, as shown in FIG. 7(a), the opening 31c and the storage chamber communication port 43 are both located in region B.

More specifically, in this embodiment, when viewed along the rotation axis direction X1 of the agitation shaft 36a in the posture during use, a perpendicular line G1 passing through the rotation center X0 of the agitation shaft 36a can be used as a reference. At this time, at least a part of the opening 31c and at least a part of the storage chamber communication port 43 are both located on one side G11 of the perpendicular line G1. In addition, the restoration portion 31a2 is located on the other side G12, which is the other side of the perpendicular line G1 that is different from the one side G11.

On the other hand, in Comparative Example 1, as shown in FIG. 7(b), the opening 31c is in region B, and the storage chamber communication port 43 is in region A.

In Comparative Example 2, as shown in FIG. 7(c), the opening 31c is in region A, and the storage chamber communication port 43 is in region B.

In Comparative Example 3, as shown in FIG. 7(d), the opening 31c and the storage chamber communication port 43 are both located in region A.

First, we will explain the difference between the position of the storage chamber communication port 43 and the mixed state of new toner and old toner in the toner storage chamber 31a.

When the storage chamber communication port 43 is in region B as in the configuration of this embodiment, the new toner supplied from the storage chamber communication port 43 is supplied into the old toner remaining at the bottom of the toner storage chamber 31a, or upstream of the old toner in the rotation of the stirring sheet 36b. Then, as the stirring sheet 36b rotates, it passes through the old toner remaining at the bottom of the toner storage chamber 31a before reaching the restoration section 31a, during which time it is actively mixed with the old toner before being transported to the development chamber 31b.

On the other hand, when the storage chamber communication port 43 is in region A as in the configurations shown in Comparative Examples 1 and 3, the new toner that is replenished is replenished into the old toner that has accumulated at the bottom of the toner storage chamber 31a, or downstream of the old toner in terms of the rotation of the agitation sheet 36b.

In other words, the distance from the storage chamber communication port 43 to the restoration section 31a2 is short, and there is little opportunity for old toner and new toner to mix. As a result, the new toner reaches the restoration section 31a2 without being sufficiently mixed with the old toner, and is transported to the development chamber.

Next, we will explain the difference between the position of the opening 31c and the mixed state of new toner and old toner in the toner storage chamber 31a.

Figure 8 is a conceptual diagram showing the circulation of toner within a development unit in an embodiment of the present invention.

Specifically, FIG. 8 shows the state after one of the agitation sheets 36b passes the restoration section 31a and transports the toner to the development chamber 31b. The toner that was not transported to the development chamber 31b falls into the toner storage chamber 31a.

First, when the opening 31c is in region B, as in the configurations shown in this embodiment and Comparative Example 1, most of the toner that flies toward the opening 31c and does not reach the developing chamber 31b and falls into the toner storage chamber 31a falls into region B (see FIG. 8). The toner that falls is then mixed and stirred with the old toner that remains at the bottom of the toner storage chamber 31a before being transported to the developing chamber.

On the other hand, when the opening 31c is in region A, as in the configurations shown in Comparative Examples 2 and 3, most of the toner that flies toward the opening 31c and does not reach the developing chamber 31b but falls into the toner storage chamber 31a falls into region A. The toner that falls is lifted by the rotation of the stirring sheet, reaches the restoration section, and flies away. In other words, it is transported to the developing chamber without being stirred and mixed with the toner that accumulates at the bottom of the toner storage chamber.

In this manner, in this embodiment, when a perpendicular line is drawn through the center of the agitation shaft in the posture during use, the opening 31c and the storage chamber communication port 43 are positioned on the different side (area B) from the restoration section 31a2, as in the configuration of this embodiment. This allows new toner and old toner to be sufficiently agitated and mixed in the toner storage chamber 31a before being transported to the development chamber 31b.

This reduces the uneven distribution of toners with different electrostatic charges in the coat on the developing roller, and prevents image defects such as "fog," toner scattering, and density unevenness, which will be described later.

In this embodiment, two sets of sheet members 36b are attached at different mounting positions on the agitator shaft 36a. This allows the toner to be agitated in the toner storage chamber 31a and transported to the developing chamber 31b more efficiently than when only one set of sheet members 36b is used.

In addition, in this embodiment, the length (free length L) of the sheet member 36b is longer than the shortest distance (L1) from the agitator shaft 36a to the storage chamber communication port 43.

In other words, when the sheet member 36b overlaps with the storage chamber communication port 43, the sheet member 36a comes into contact with the storage chamber communication port 43. This increases the conveying force for the new toner supplied from the storage chamber communication port 43, making it possible to efficiently mix the new toner with the old toner.

<Effectiveness verification experiment>
In order to verify the effect of this embodiment, the following experiments were carried out for Comparative Examples 1, 2, and 3.

A two-sheet intermittent printing durability test was conducted under normal temperature and humidity conditions (temperature 23°C, humidity 60%). In this printing durability test, horizontal lines with an image ratio of 1% were printed.

In addition, in this experiment, the process cartridge 70 was started with 200 g of toner filled, and every time 10 g of toner was lost, 10 g of toner was replenished from the toner cartridge 9. The print durability test was then performed until the amount of use in the process cartridge 70 reached 100%, and the occurrence of fogging was judged according to the following criteria.

Next, we will conduct an experiment to evaluate image defects caused by "fog."

"Fogging" refers to an image defect that appears like smearing due to a small amount of toner being developed in unexposed areas that are not supposed to be printed.

The image forming device is stopped while a solid white image is being printed. 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. A tape without toner is also attached to the same recording paper at the same time. The optical reflectance of the tape attached to the recording paper is measured using an optical reflectance measuring device (TC-6DS manufactured by Tokyo Denshoku Co., Ltd.) with a green filter, and this is subtracted from the reflectance of the tape without toner to determine the amount of reflectance of the fog, which is evaluated as the amount of fog. The amount of fog is measured at three or more points on the tape and the average value is calculated.

A: The amount of fog is less than 1.0%.
B: The amount of fog is 1.0 to less than 3.0%.
C: The amount of fog is 3.0 to less than 5.0%.
D: The amount of fog is 5.0% or more.

The evaluation results are shown in Table 2.

In the configuration of this embodiment, new toner and old toner are mixed sufficiently in the toner storage chamber 31a, so that the occurrence of fogging can be suppressed even when the process cartridge is used further and new toner is replenished when the old toner has deteriorated.

On the other hand, in the configuration of Comparative Example 1, since the storage chamber communication port 43 is located in area A, the new toner supplied from the storage chamber communication port 43 is transported to the developing chamber 31b without being sufficiently mixed with the old toner. This causes "fogging" when the usage amount of the process cartridge approaches 100%.

In addition, in the configuration of Comparative Example 2, because the opening 31c is located in area A, most of the toner that is not transported to the developing chamber 31b and falls into the toner storage chamber 31a falls near the restoration section 31a2, making it difficult for the toner to mix with the toner remaining at the bottom of the toner storage chamber 31a. As a result, as in Comparative Example 1, "fogging" occurred when the process cartridge was used up.

In addition, in the configuration of Comparative Example 3, the storage chamber communication port 43 and the opening 31c are both in area A, which results in less mixing of toner in the toner storage chamber 31a than in the configurations of Comparative Examples 1 and 2. This caused "fogging" to occur even when the process cartridge was not yet used to a relatively large extent.

In this way, there is a relationship between the arrangement of the storage chamber communication port 43 and the opening 31c and the toner mixing state within the toner storage chamber 31a, and by adopting the configuration of this embodiment, it was possible to suppress the occurrence of "fogging" without providing additional components or a complex configuration.

The present invention makes it possible to suppress the occurrence of "fog" caused by differences in the charging ability of toner when toner is replenished using a simple configuration.

The configuration of the present invention can be summarized as follows:

(1) The developing device (4) of the present invention is
a developing frame (31) including a developing chamber (31b) in which a developer carrier (25) that carries a developer is housed, a developer storage chamber (31a) located below the developing chamber in an orientation during use and storing the developer, and a communication port (31c) that communicates the developing chamber with the developer storage chamber;
and a transport member provided in the developer storage chamber (31a) for transporting the developer stored in the developer storage chamber to the developing chamber (31b).

The conveying member (36) includes a rotatable shaft portion (36a) and a sheet portion (36b) having one end (36b1) fixed to the shaft portion and the other end (36b2) which is a free end and can be elastically deformed.

The developing device (4) is
a deformation portion (31a1) provided in the developer storage chamber (31a) and contacting a free end (36b2) of a sheet portion (36b) that rotates in accordance with the rotation of the rotation shaft portion (36a) to bend and elastically deform the sheet portion;
The developer storage chamber (31a) further includes a restoring portion (31a2) provided in the developer storage chamber (31a) at a position upstream of the communication port (31c) and downstream of the deformation portion (31a1) in the rotation direction (X2) of the rotation shaft portion (36a).

The restoring portion (31a2) is configured to release and restore the sheet portion (36b) that has been elastically deformed by the deformation portion (31Aa1), thereby causing the developer carried on the sheet portion to fly toward the communication port (31c).

In addition, the developer storage chamber (31a) is provided with a supply port (43) for supplying developer from the outside to the developer storage chamber,
In the position during use, when viewed along the rotation axis direction (X1) of the rotating shaft portion (36a), when a perpendicular line (G1) passing through the rotation center (X0) of the rotating shaft portion (36a) is used as a reference,
At least a part of the communication port (31c) and at least a part of the supply port (43) are both located on one side (G11) with respect to the perpendicular line (G1);
The restoration portion (31a2) is located on the other side (G12) with respect to the perpendicular line (G1).

(2) In the developing device of the present invention,
The seat portion (36b) may have a free length (L) longer than the shortest distance (L1) from the rotation center (X0) of the rotating shaft portion (36a) to the supply port (43).

(3) In the developing device of the present invention,
In the posture during use, the highest position (P11) of the supply port (43) may be located lower than the lowest position (P21) of the restoring portion (31a2). In the present invention, the lowest position of the restoring portion (31a2) is the position at which the free end (36b2) of the sheet portion (36b) starts to change from a state of contact with the inner wall surface of the developing frame constituting the restoring portion (31a2) to a state of separation during rotation.

(4) In the developing device of the present invention,
In the posture during use, the highest position (P11) of the supply port (43) may be located lower than the highest position (P31) of the deformation portion (31a1). The highest position of the deformation portion (31a1) is the position on the inner wall surface of the developing frame constituting the deformation portion (31a1) that is the shortest distance from the rotation center X0 of the rotation shaft portion (36a).

(5) In the developing device of the present invention,
The seat portion (36b) includes a first seat portion (36b3) and a second seat portion (36b4),
The first seat portion (36b3) and the second seat portion (36b4) may be attached to the rotating shaft portion (36a) at different positions (X21, X22) in the rotation direction (X2).

(6) In the developing device of the present invention,
The first sheet portion (36b3) and the second sheet portion (36b4) may be fixed to both sides (36a1, 36a2) of the rotating shaft portion (36a) with the rotation center (X0) in between,
The first sheet portion (36b3) and the second sheet portion (36b4) may be arranged such that their free ends (36b2) extend in opposite directions (D1, D2).

(7) In the developing device of the present invention,
In the position during use, the highest position (P11) of the supply port (43) may be located above the developer surface (LV) of the developer contained in the developer containing chamber (31a) in the unused state.

(8) In the developing device of the present invention,
The developing chamber (31b) may be provided with a supply member (34) that comes into contact with the developer carrier (25) and supplies the developer to the developer carrier.

(9) In the developing device of the present invention,
The developer may be a one-component non-magnetic developer.

(10) In the developing device of the present invention,
The developing device (4) may be detachable from the image forming device (100) that forms an image.

(11) The process cartridge (70) of the present invention comprises:
An image carrier (1) that carries a developer image;
The developing device (4) is detachably attached to the image forming apparatus (100).

(12) In the process cartridge of the present invention,
The developer carrier (25) may be configured to collect the developer remaining on the front carrier (1) after the developer image has been transferred from the image carrier (1).

(13) The image forming apparatus (100) of the present invention comprises:
At least one of the developing device (4) or the process cartridge (70);
A transfer member (58).

4. Development unit (developing device)
25 Developing roller (developer carrier)
31 Developing frame 31a Toner storage chamber (developer storage chamber)
31a1 Deformation portion 31a2 Restoration portion 31b Development chamber 31c Opening (communication port)
36 Toner transport member (transport member)
36a Agitation shaft (rotating shaft part)
36b Sheet member (sheet portion)
36b1 One end (fixed end)
36b2 other end (free end)
43 Storage chamber communication port (supply port)
G1 Perpendicular line G11 One side (relative to the perpendicular line) G12 The other side (relative to the perpendicular line) X0 Center of rotation X1 Direction of the rotation axis

Claims (13)

a developing frame including a developing chamber in which a developer carrier that carries a developer is accommodated, a developer accommodating chamber that is located below the developing chamber in an orientation during use and accommodates the developer, and a communication port that communicates the developing chamber with the developer accommodating chamber;
a transport member provided in the developer storage chamber and configured to transport the developer stored in the developer storage chamber to the developing chamber, the transport member including a rotatable shaft portion and a sheet portion having one end fixed to the shaft portion and the other end being a free end and capable of elastic deformation;
a deformation portion that is provided in the developer accommodating chamber and that comes into contact with the free end of the sheet portion that rotates in accordance with the rotation of the rotation shaft portion, thereby bending and elastically deforming the sheet portion;
a restoring portion that is provided in the developer accommodating chamber at a position upstream of the communication port and downstream of the deformation portion in a rotation direction of the rotating shaft portion, and that releases and restores the sheet portion that has been elastically deformed by the deformation portion, thereby causing the developer carried on the sheet portion to fly toward the communication port;
A developing device having
the developer storage chamber is provided with a supply port for supplying developer from the outside to the developer storage chamber,
When viewed along the rotation axis direction of the rotating shaft portion in a posture during use, when a perpendicular line passing through the rotation center of the rotating shaft portion is used as a reference,
at least a portion of the communication port and at least a portion of the supply port are both located on one side of the perpendicular line;
The developing device, wherein the restoring portion is located on the other side of the perpendicular line. The developing device according to claim 1, characterized in that the seat portion has a free length longer than the shortest distance from the center of rotation of the rotating shaft portion to the supply port. The developing device according to claim 1 or 2, characterized in that, in a position during use, the highest position of the supply port is located below the lowest position of the restoration portion. The developing device according to any one of claims 1 to 3, characterized in that, in a position during use, the highest position of the supply port is located below the highest position of the deformation portion. The sheet portion includes a first sheet portion and a second sheet portion,
5. The developing device according to claim 1, wherein the first seat portion and the second seat portion are attached to the rotating shaft portion at different positions in the rotation direction. The first seat portion and the second seat portion are fixed to both sides of the rotation shaft portion with the rotation center in between,
6. The developing device according to claim 5, wherein the first sheet portion and the second sheet portion are arranged such that their free ends extend in opposite directions. The developing device according to any one of claims 1 to 6, characterized in that, in a position during use, the highest position of the supply port is located above the developer surface of the developer contained in the developer storage chamber when the device is not in use. The developing device according to any one of claims 1 to 7, characterized in that the developing chamber is provided with a supply member that contacts the developer carrier and supplies developer to the developer carrier. The developing device according to any one of claims 1 to 8, characterized in that the developer is a one-component non-magnetic developer. The developing device according to any one of claims 1 to 9, characterized in that the developing device is detachable from an image forming device that forms an image. an image carrier that carries a developer image;
11. A process cartridge comprising: the developing device according to claim 1; and the process cartridge being detachably mountable to an image forming apparatus. The process cartridge according to claim 11, characterized in that the developer carrier collects the developer remaining on the image carrier after the developer image is transferred from the image carrier. At least one of the developing device according to any one of claims 1 to 10 and the process cartridge according to claim 11 or 12,
A transfer member;
An image forming apparatus comprising:

Images