JP2003215922A - Developing device, process cartridge and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a developing device, a process cartridge and an image forming apparatus by which toner is uniformly taken in a width direction without being affected by a wall surface at the end part of a toner replenishment path in the width direction orthogonal with a developer feeding direction on a developing sleeve. <P>SOLUTION: The value of a peak magnetic flux density in a normal direction on the surface of the developing sleeve 4 by a toner uptake pole P<SB>4</SB>extended in a width direction orthogonal with a developer feeding direction on the developing sleeve 4 at the end part of the toner uptake pole P<SB>4</SB>in the width direction is set larger than the average value of the peak magnetic flux density in the normal direction at a part at which the toner uptake pole P<SB>4</SB>is extended in the width direction. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as a copying machine, a printer and a facsimile, and a developing device and a process cartridge used in the image forming apparatus.

[0002]

2. Description of the Related Art Conventionally, there is a developing device capable of controlling the toner concentration of a developer on a developer carrying member within a certain range (hereinafter referred to as "self-toner concentration control") without requiring a toner concentration detecting means. Known (for example, Japanese Patent Laid-Open No. 9-1
(See Japanese Patent Laid-Open No. 97833/1997 and Japanese Patent Laid-Open No. 9-22178). In these developing devices, in the width direction orthogonal to the developer carrying direction on the developer carrier, a part where the movement of the developer is partially active and a part where it is not active, or a part where the amount of the developer is partly large. The amount of toner taken in differs in a small number of areas, and the toner density becomes unstable partially, and image density unevenness (black band density unevenness, wavy density unevenness) is likely to occur. Therefore, attempts have been made to stabilize the toner density by improving the mechanism of the toner intake section that takes in the toner into the developer on the developer carrying member to realize more stable and uniform image density. For example, as shown in FIG. 1, in addition to the doctor 6 serving as the first developer regulating member that regulates the amount of the developer carried on the developing sleeve 4 serving as the developer carrying body and conveyed toward the developing area, A pre-doctor 7a is provided on the upstream side of the developer accommodating portion S in the developer conveying direction on the developing sleeve 4 as a second developer regulating member for regulating the amount of the developer carried and conveyed on the developing sleeve 4. ing. Here, in the magnet roller 5 as a magnetic field generating means fixedly arranged inside the developing sleeve 4, at a position facing the toner supply path 8a, a width direction ( A magnetic pole for taking in toner (P4) that extends in the axial direction and the longitudinal direction.
Poles) are provided. Further, a magnetic pole (P5 pole) extending in the width direction for developer transport stirring is provided at a position opposed to the developer accommodating portion S. In this developing device, when the toner concentration of the developer is within the proper range, the developer retaining portion 30 is formed in the toner supply path 8a. Then, the developer and the toner are not mixed with each other where the toner 3a and the developer are in contact with each other, so that the toner is not taken in. When the toner is consumed, the bulk of the developer is reduced and the developer retaining portion 30 is reduced, so that the developer circulates under the predoctor 7a. When the toner comes into contact with the developer circulating portion 31, the toner is taken into the circulating developer and becomes bulky, the developer accumulating portion 30 is formed again in the toner supply path 8a, and the toner taking is interrupted. In order to realize such an operation, the arrangement and magnetic force of the magnetic poles inside the developing sleeve 4, the position of the predoctor 7a, the shape and position of the space for circulating the developer formed on the front side thereof, and the toner replenishment path. To optimize the relative positional relationship of 7a,
It realizes reduction of uneven density.

In the developing device illustrated in FIG. 1, the developer on the developing sleeve 4 is not separated from the developing sleeve 4 but circulates therewith. Therefore, since there is almost no replacement with the developer forming the developer circulating portion 31 in the toner replenishing passage 8a, the stress on the carrier in the developer becomes very large, and the life as a developer becomes short. there were. Therefore, by providing a peeling roller 11 which rotates in the vicinity of the surface of the developing sleeve in the developer accommodating portion S, the developer is intentionally peeled from the developing sleeve 4, and the developer circulating portion 31.
Replacing the developer inside with the developer on the developing sleeve 4,
Some measures have been taken to eliminate the above problems (see, for example, Japanese Patent Laid-Open No. 13-166580).

[0004]

However, in the developing device as shown in FIG. 1, even if the predoctor 7a or the peeling roller 11 is provided, the widthwise direction (axial direction, longitudinal direction) on the developing sleeve is increased. In some cases, the image density becomes low on the edge side of the (direction). The cause of the decrease in image density at the end portion in the width direction is considered to be the presence of the wall surface of the casing 2a provided at both end portions in the width direction. For example, a wall surface of the casing 2a is required at both ends of the toner replenishing path 8a in the width direction so as to prevent the developer from splashing out of the apparatus due to circulation. The developer existing at both widthwise end portions of the toner supply path 8a constantly contacts the wall surfaces at both end portions thereof and circulates therethrough, so that the developer always receives a frictional resistance force from the wall surface. Therefore, the developer circulating state at both widthwise end portions of the toner supply path 8a becomes slower than the other portions by the frictional resistance from the wall surface, and the toner intake force becomes weaker than the other portions. As a result, the toner density of the developer at both ends in the width direction becomes lower than that in other areas, and the image density becomes low. Also,
Both ends of the developer accommodating portion S in the width direction also need a wall surface of the casing 2a that covers to prevent the developer from jumping out of the apparatus due to circulation. Since the developer existing in the developer accommodating portion S is always in contact with the wall surfaces existing at both ends of the developer and circulates, the developer is always subjected to the frictional resistance force from the wall surfaces. Due to this frictional resistance force, the developer conveying force at both widthwise end portions of the developer accommodating portion S becomes weaker than the other portions by the frictional resistance from the wall surface. Therefore, the amount of the developer supplied to the gap (doctor gap) between the doctor 6 and the developing sleeve 4 at both end portions in the width direction is smaller than that in other portions. Therefore, a sufficient amount of developer is not secured at both ends of the developing area in the width direction, and a defective image occurs.

The present invention has been made in view of the above problems, and a first object thereof is a wall surface at an end portion of a toner replenishing path in a width direction orthogonal to a developer carrying direction on a developer carrying member. (EN) Provided are a developing device capable of uniformly taking in toner in the width direction without being affected by the above, a process cartridge and an image forming apparatus including the developing device. A second object of the present invention is that the developer can be uniformly supplied to the developing area in the width direction without being affected by the wall surface at the end of the developer accommodating portion in the width direction. To provide a developing device, a process cartridge including the device, and an image forming apparatus.

[0006]

In order to achieve the first object, the invention of claim 1 has a magnetic field generating means inside and carries a developer containing a toner and a magnetic carrier and conveys the developer. And a first developer regulating member that regulates the amount of the developer carried by the developer carrying body and conveyed toward the developing area. The developer containing section for containing the developer blocked by the developer regulating member and the developer carrying section on the upstream side of the developer containing section in the developer carrying direction on the developer carrying body are carried and carried by the developer carrying body. A second developer regulating member for regulating the amount of the developer;
And a second developer regulating member which adjoins the developer regulating member of the developer carrying member on the developer carrying member from the upstream side in the developer carrying direction, and the toner contained in the developer carrying member is carried and carried by the developer carrying member. A toner accommodating portion having a toner replenishing passage in contact with the developer blocked by the member, and the layer thickness of the developer existing in the toner replenishing passage as the toner concentration of the developer on the developer carrying member increases. The gap between the second developer regulating member and the surface of the developer carrying member is set so as to regulate the increase when the toner storage amount increases, and the movement of the developer in the toner replenishing path causes the toner storage In a developing device adapted to take in the toner in the developer into the developer, the magnetic field generating means extends in a width direction orthogonal to the developer carrying direction on the developer carrying member at a position facing the toner replenishing path. The toner has a magnetic pole for taking in toner The value of the peak magnetic flux density in the normal direction on the surface of the developer carrying member by the magnetic pole for taking in at the end portion of the magnetic pole in the width direction is about the portion where the magnetic pole extends in the width direction. Is larger than the average value of the peak magnetic flux density in the normal direction. In the developing device according to the first aspect, the value of the peak magnetic flux density in the normal direction on the surface of the developer carrier by the magnetic pole for taking in toner, at the end portion of the magnetic pole for taking in toner in the width direction, It is set to be larger than the average value of the peak magnetic flux density in the normal direction in the portion where the magnetic poles for taking in toner in the width direction extend. As a result, at the end of the toner replenishing path in the width direction, the developer is carried on the surface of the developing carrier with a stronger force than that of the other parts inside the both ends and conveyed. Therefore, even if the developer receives a frictional force from the wall surface at the end portion of the toner replenishing path, the same circulation state of the developer as in other portions can be secured, and a predetermined amount of toner can be taken in. . In order to achieve the above-mentioned second object, the invention of claim 2 has a magnetic field generating means inside and carries a developer carrying a developer containing a toner and a magnetic carrier and moving the surface so as to convey the developer. Body, a first developer regulating member for regulating the amount of the developer carried by the developer carrying body and conveyed toward the developing area, and a developer blocked by the first developer regulating member And a developer accommodating portion for accommodating the developer, and a second part for regulating the amount of the developer carried and carried by the developer carrying body on the upstream side of the developer carrying section in the developer carrying direction on the developer carrying body. The developer regulating member and the second developer regulating member are adjacent to each other from upstream in the developer conveying direction on the developer carrying member, and the contained toner is carried and carried by the developer carrying member. The toner replenishment path that comes into contact with the developer and the developer blocked by the second developer regulating member And a toner accommodating portion for controlling the increase in the layer thickness of the developer existing in the toner replenishment path as the toner concentration of the developer on the developer carrier increases. A gap is set between the second developer regulating member and the surface of the developer carrying member, and the toner in the toner accommodating portion is taken into the developer by the movement of the developer existing in the toner supply path. In the developing device, the magnetic field generating means has magnetic poles for stirring developer transport which extend in a width direction orthogonal to the developer transport direction on the developer carrier at a position facing the developer accommodating portion. And the value of the peak magnetic flux density in the normal direction on the surface of the developer carrying member due to the magnetic pole for stirring and conveying the developer at the end of the magnetic pole in the width direction is extended by the magnetic pole in the width direction. Of the normal direction peak magnetic flux density of the existing portion It is characterized in that greater than average value. In the developing device according to the second aspect, the value of the peak magnetic flux density in the normal direction on the surface of the developer carrier by the magnetic poles for stirring and conveying the developer is measured at the end portion of the magnetic poles for stirring and conveying the developer in the width direction. , The average value of the peak magnetic flux density in the normal direction in the portion where the magnetic poles for stirring the developer transport in the width direction extends. Thereby, at the end portion of the developer accommodating portion in the width direction,
The developer is carried on the surface of the development carrier with a stronger force than that of the other parts inside the both end portions and conveyed. Therefore,
Even if the developer receives a frictional force from the wall surface at the end of the developer accommodating portion, the same carrying force for the developer as other parts can be secured, and a predetermined amount of the developer is carried to the developing area. Like The invention of claim 3 is the same as claim 1 or 2.
In the developing device, the peeling member, which comes into contact with or comes close to the surface of the developer carrying member in the developer containing portion, peels off at least a part of the developer carried and conveyed by the developer carrying member. It is characterized by that. According to a fourth aspect of the present invention, in a process cartridge including a latent image carrier and a developing device that develops a latent image on the latent image carrier to form a toner image, the developing device may be the developing device. Alternatively, the third developing device is provided. According to a fifth aspect of the invention, a latent image carrier, a latent image forming means for forming a latent image on the latent image carrier, and a developing device for developing the latent image on the latent image carrier to form a toner image. And a transfer device for transferring the toner image on the latent image carrier to a transfer material, wherein the developing device comprises the developing device according to claim 1, 2 or 3. To do.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment in which the present invention is applied to a developing device of a laser printer (hereinafter referred to as "printer") which is an electrophotographic image forming apparatus will be described. First, the outline of the printer according to the present embodiment will be described with reference to FIG. The photosensitive drum 1 as a latent image carrier is uniformly driven by a charging roller 50 as a charging unit while being rotationally driven in the direction of arrow A in the figure. After that, the photoconductor drum 1 is scanned and exposed by the optical writing unit 51 based on the image information to form an electrostatic latent image on the surface. In the present embodiment, the charging roller 50 and the optical writing unit 51 constitute the latent image forming means, but other types of charging device or exposure device may be used. The electrostatic latent image formed on the photosensitive drum 1 is developed by the developing device 2 described later, and a toner image is formed on the photosensitive drum 1. The toner image formed on the photosensitive drum 1 is transferred from the paper feed cassette 54 to the paper feed roller 5 by a transfer unit having a transfer roller 53 as a transfer device.
5. The image is transferred onto the sheet 52 as a transfer material that is conveyed through the registration roller pair 56. Paper 52 after transfer
The toner image is fixed by the fixing unit 57 and is discharged out of the apparatus. The residual toner on the photosensitive drum 1 that has not been transferred is removed from the photosensitive drum 1 by the cleaning unit 58. In addition, the residual charge on the photosensitive drum 1 is removed by the static elimination lamp 59.

Next, the overall structure of the developing device according to this embodiment will be described. FIG. 1 is a schematic configuration diagram of the entire developing device 2. The developing device 2 is disposed on the side of the photoconductor drum 1 and includes a two-component developer (hereinafter referred to as "developer") including a toner 3a and a magnetic carrier (hereinafter referred to as "carrier").
Say. 3) is provided on the surface of the developing sleeve 4 made of a non-magnetic material as a developer carrying member. The developing sleeve 4 is attached so as to be partially exposed from an opening formed in the casing 2a on the photosensitive drum 1 side. Then, by a driving device (not shown), it can be rotationally driven in a direction in which the developer is moved downward (in the direction of arrow B in the drawing) in the developing area facing the photosensitive drum 1. Further, inside the developing sleeve 4, a magnet roller 5 composed of a fixed magnet group as a magnetic field generating means is fixedly arranged.

Further, the present developing device is provided with a doctor 6 as a first developer regulating member which regulates the amount of the developer carried on the developing sleeve 4 and conveyed toward the developing area. Further, as a toner accommodating portion, a developer accommodating case 7 provided so as to form a developer accommodating portion S for accommodating the developer 3 between the surface of the developing sleeve 4 and the doctor 6 on the upstream side in the developer conveying direction. The toner hopper 8 and the like are also provided. The toner hopper 8 has a toner replenishing passage 8a adjacent to the upstream side of the developer accommodating portion S in the developer conveying direction on the developing sleeve 4 and facing the surface of the developing sleeve. Further, inside the toner hopper 8, the toner 3a is rotated in the clockwise direction shown by an arrow C in the figure and the toner supply path 8
A toner agitator 9 is provided as a toner stirring member that sends the toner to the sheet a while stirring.

The developing sleeve 4 of the developer accommodating case 7
The tip portion (eave portion) close to is used as a pre-doctor 7a as a second developer regulating member. The predoctor 7a regulates the amount of the developer to which the toner is replenished from the toner hopper 8 and progresses toward the inside of the developer accommodating portion S. Further, in the developer containing portion S formed by the developer containing case 7 or the like, the developer which is not supplied to the developing area facing the photosensitive drum 1 and whose progress is blocked by the doctor 6 is stored. .

On the surface of the magnet roller 5, a plurality of magnetic poles extending in a direction along the central axis of the magnet roller 5 are formed so that S poles and N poles are alternately arranged in the circumferential direction. . Specifically, a developing magnetic pole (P1 pole) is arranged at a position facing the photoconductor drum 1. Then, from there, the developer carrying magnetic pole (P2
Pole, P3 pole), a magnetic pole for taking in toner (P4 pole), a magnetic pole for stirring developer transport (P5 pole), and a magnetic pole for developer transport (P6 pole). Here, the magnetic pole for taking in the toner (hereinafter referred to as "toner taking-in pole") P4 is arranged so as to face the toner supply path 8a. Further, the magnetic pole for stirring the developer transport (hereinafter referred to as “developer stirring pole”) P5 is arranged at a position facing the developer storage portion S. Curves B1 to B6 in FIG. 1 represent distributions of magnetic flux density in the normal direction generated on the surface of the developing sleeve by the magnetic poles (P1 pole to P6 pole), respectively. In this embodiment, a fixed magnet body in which a magnet piece is fitted and fixed to a base material, that is, a so-called block type magnet roller is used, but the present invention is not limited to this. For example, it goes without saying that a so-called ferrite-based integrated plastic magnet roller, which is manufactured by magnetizing a plastic magnet material molded into a predetermined shape at the same time as magnetic orientation, may be used.

The developing device also includes a peeling roller 11 as a roller-shaped peeling member formed of a magnetic material. The peeling roller 11 faces the surface of the developing sleeve 4 in the developer accommodating portion S in a non-contact manner, and peels off a part of the developer carried on the developing sleeve 4 (surface layer portion of the conveyed developer). The peeling roller 11 may have a cylindrical shape or a cylindrical shape, and its internal structure is not limited to a specific structure. As the material (magnetic material) of the peeling roller 11, for example, SUM material (sulfur and sulfur composite free-cutting steel material), SUS material having magnetism, iron, nickel or the like can be used. Alternatively, an iron core plated with nickel, a stainless steel material coated with a magnetic material, or the like can be used. The surface of the peeling roller 11 is preferably roughened by sandblasting or the like so that the developer peeled from the developing sleeve can be carried and carried well. For example, roughening is performed so that the surface roughness (10-point average roughness Rz) is about 30 μm. The surface roughness is set so that the toner can be conveyed according to conditions such as the type of toner and the material of the peeling roller.

The peeling roller 11 is driven to rotate in the same rotation direction as the developing sleeve 4 (direction of arrow E in the figure) by a driving device (not shown). By this rotational driving, the surface of the peeling roller 11 moves in the opposite direction to the surface of the developing sleeve at the portion where the developing sleeve 4 and the peeling roller 11 face each other. As a result, the upper layer portion of the developer on the developing sleeve 4 can be blocked by the peeling roller 11 and reliably peeled off. Then, the peeled developer is rotated along with the movement of the surface of the peeling roller 11, moves away from the surface of the developing sleeve, and is mixed with the stored developer in the developer storage portion S.

Next, the developing operation of the developing device having the above-mentioned structure will be described with reference to FIG. The developer 3 on the developing sleeve 4 is conveyed as the developing sleeve 4 rotates in the direction of the arrow B, and is regulated by the doctor 6 to form a thin layer. The thinned developer 3 is conveyed to a developing area facing the photoconductor drum 1 rotating in the direction of arrow A. In this developing area, toner is supplied to the electrostatic latent image formed on the photosensitive drum 1 to visualize the electrostatic latent image. The developer on the developing sleeve 4 that has passed through the developing area is further conveyed as the developing sleeve 4 rotates, and reaches the position facing the toner supply path 8a. In this toner supply path 8a,
The toner 3a in the toner hopper 8 is sent out by the agitator 9 and stays in contact with the developer on the developing sleeve 4. After taking in the new toner 3a through the toner supply path 8a, the process returns to the developer accommodating portion S. And new toner 3
The internal pressure of the developer 3 containing a increases at the regulating portion by the doctor 6. In the developer with the increased internal pressure, the toner is charged by frictional charging with the carrier. On the other hand, a part of the developer 3 which is not supplied to the developing area and is prevented from advancing by the doctor 6 moves so as to circulate in the developer accommodating portion S.

The self toner concentration control during the developing operation in the present developing device is performed as follows. When the toner concentration of the developer is within the proper range, the developer retaining portion 30 is formed in the toner supply path 8a. Since the developer and the toner are not mixed with each other in the area where the developer and the toner are in contact with each other, the toner is not taken in. When the toner is consumed, the bulk of the developer is reduced and the developer retention portion 30 is reduced, so that the developer circulates under the predoctor 7a. This circulating state becomes active in proportion to the value of the peak magnetic flux density in the normal direction on the surface of the developing sleeve by the toner intake pole (P4 pole). In order to prevent the developer from splashing out of the machine due to the circulation of the developer in the toner supply path 8a, the wall surface 20 (see FIG. 3) of the casing 2a covers the widthwise end portion of the toner supply path 8a. Exists. When the toner 3a comes into contact with the developer circulating portion 31 in which the developer circulates in the toner supply path 8a, the toner 3a is taken into the circulating developer and the bulk of the developer increases. When the bulk of the developer increases, the developer retaining portion 30 is formed again in the toner replenishing path 8a, and the toner intake is interrupted.
Further, the developer carried on the developing sleeve 4 is
It is peeled off by the peeling roller 11 made of a magnetic material which is installed close to the developing sleeve 4, and the mixing and replacement with the developer in the developer accommodating portion S are efficiently performed. Most of the developer carried on the developing sleeve 4 and passed through the gap between the predoctor 7a and the developing sleeve 4 is braked by the peeling roller 11. While being subjected to this braking action, the developer is peeled off from the surface of the developing sleeve, and is mixed with the developer that has newly passed through the gap between the developing sleeve 4 and the predoctor 7a and rises up the inner wall of the developer accommodating case 7. Then, it is conveyed by the peeling roller 11 magnetized by the magnetic force of the developer stirring pole (P5 pole) in the developing sleeve 4, and heads toward the gap between the doctor 6 and the developing sleeve 4.

Here, when the developer circulating portion 11 in the toner replenishing passage 8a takes in the toner and reaches a predetermined toner concentration, a developer retaining portion is provided at a contact portion between the toner and the developer in the toner replenishing passage 8a. In order to make 30 appear, it is necessary to optimize various conditions. Specifically, the arrangement and magnetic force of the toner intake pole (P4 pole) and the developer stirring pole (P5 pole), the position of the predoctor 7a, the shape and position of the space for circulating the developer, and the toner supply path 8a. It is necessary to optimize the relative positional relationship of the. Tables 1 and 2 show an example of the conditions under which the inventor performed the above optimization based on the experimental results. The dimensions and angles of the experimental conditions in the table are as shown in FIG.

[Table 1]

[Table 2]

By the above-mentioned condition setting, the operation of the self toner concentration control described above can be performed, and the toner concentration of the developer can be stabilized. The above operation can be reproduced under different conditions by combining these conditions, and the conditions shown in Tables 1 and 2 above are examples.

Next, the structure of the characteristic part of the present invention will be described. As described above, the wall surface 20 (see FIG. 3) of the casing 2 is present at both axial ends of the toner supply passage 8a in which the developer circulating portion 31 is formed for the purpose of preventing the developer from being discharged from the machine. When the developer near the wall surface 20 circulates, the wall surface 2
Always receives friction resistance from 0. In the developing device of the present embodiment, as described above, the value of the peak magnetic flux density in the normal direction of the toner intake pole P4 almost determines the circulating state of the developer circulating portion 31. However, in the conventional developing device, the peak magnetic flux density in the normal direction of the toner intake pole P4 is manufactured to be substantially uniform in the axial direction of the developing sleeve 4, which is the width direction orthogonal to the developer conveying direction. Therefore, the circulation state in the vicinity of the wall surface 20 of the developer circulation portion 31 is slower than the other portions in the axial direction. In the self-toner concentration control system, the more the circulation state of the developer circulation unit 31 is, the larger the toner intake amount until the toner intake is stopped, and the equilibrium toner concentration (toner that stabilizes by continuously printing the image area of about 5%). Concentration) becomes higher. for that reason,
There is a problem that a thin image is generated only at the edge portion of the image, or conversely, the toner density is too high in a portion other than the edge portion, which causes background stain. Therefore, in the developing device of the present embodiment, the peak magnetic flux density in the normal direction at the end portion in the axial direction by the toner intake pole P4 is made larger than that in the other portions. As a result, the circulation state at the end of the developer circulation portion 31 is maintained in the same manner as the other portions, and the equilibrium toner concentration is made to approach uniformly in the axial direction of the developing sleeve 4 to prevent the occurrence of defective images and the like. In the present embodiment, the peak magnetic flux density in the normal direction due to the toner intake pole P4 is 20 mm from both ends of the toner intake pole, and the toner intake pole P4 in the width direction (developing sleeve axial direction) is 2 to 4 more than the average value of the peak magnetic flux density in the normal direction for the extended portion
Only mT higher. As a result, the equilibrium toner concentration deviation (difference between the average in the range of 20 mm at both ends and the average of other portions) was within 1% by mass. On the other hand, the equilibrium toner concentration deviation in the conventional developing device is 2% by mass or more.

Further, in the developing device of this embodiment, most of the toner taken into the developer accommodating portion S by the toner taking-in pole P4 is peeled off from the developing sleeve 4 by the peeling roller 11 together with the developer. And the peeling roller 1
1 is conveyed above and is sent to the doctor 6. Since the developer stirring pole P5 faces the peeling roller 11, the peeling roller 11 made of a magnetic material is magnetized. It has been confirmed that due to this magnetization, the magnetic pole arrangement is such that the peak magnetic flux density in the normal direction on the surface of the developing sleeve by the developer stirring pole P5 is increased. As the peeling roller 11 is strongly magnetized in this way, the above-described toner carrying force becomes larger. Therefore, if the peeling roller 11 has the same material and shape, the peak magnetic flux density in the normal direction by the developer stirring pole 15 is the carrying force. Can be said to have decided. However, both ends of the developer storage portion S are of course partitioned by the wall surface. Therefore, from the same principle as in the case of the toner replenishing path, if the peak magnetic flux density in the normal direction in the developing sleeve axial direction is uniform, the carrying force at both axial end portions (near the wall surface) is compared to other portions. become weak. Therefore, the amount of the developer supplied to the gap between the doctor 6 and the developing sleeve 4 is smaller than that in other portions, and a sufficient amount of the developer is not secured in the developing area,
There was a problem that a defective image was generated. Therefore, in the present embodiment, the peak magnetic flux density in the normal direction due to the developer stirring pole P5 is 20 mm from both ends of the developer stirring pole P5.
2 to 4 mT larger than the average value of the peak magnetic flux density in the normal direction in the widthwise direction (developing sleeve axial direction) at the end of the range where the developer stirring pole P5 extends. . As a result, in the conventional device, the developer is stagnant due to the weak conveying force near the wall surface, but the developer is conveyed at the end portion near the wall surface as well as other portions. Therefore, the amount of the developer in the developer accommodating portion S is also kept uniform in the axial direction, and an appropriate amount of the developer is supplied to the developing area.

As described above, according to the present embodiment, even if the developer receives a frictional force from the wall surface 20 at the axial end portion of the toner replenishing passage 8a, the same circulation state of the developer as other portions is secured. Therefore, the predetermined toner is taken in. Therefore, the toner can be taken in uniformly in the axial direction of the developing sleeve without being affected by the wall surface at the end of the toner supply path 8a. Further, the developer accommodating portion S
Even if the developer receives a frictional force from the wall surface at the axial end portion, the same carrying force for the developer as other parts can be secured, and a predetermined amount of the developer can be carried to the developing area. . Therefore, the developer can be uniformly supplied to the developing area in the axial direction of the developing sleeve without being affected by the wall surface at the end of the developer accommodating portion S. Further, in the present embodiment, the developer accommodating portion is accommodated. A peeling roller 11 made of a magnetic material is provided as a peeling member that comes into contact with or approaches the surface of the developing sleeve in the portion S and peels off at least a part of the developer carried and conveyed by the developing sleeve 4. The developer peeled off by the peeling roller 11 is mixed with the developer contained in the developer container S. By mixing the developer, the toner taken into the developer is agitated and dispersed, and the charging of the toner due to the frictional charging between the toner in the developer and the magnetic carrier is promoted.
As a result, the distribution and charge amount of the toner in the developer conveyed to the developing area by the developing sleeve 4 become uniform. Therefore, it is possible to further perform good development without unevenness in development density in the axial direction of the development sleeve.

In this embodiment, the process cartridge may be constructed by integrally combining the photosensitive drum 1 as a latent image carrier and the developing device 2. In the configuration example of the process cartridge 100 shown in FIG. 5, a cleaning device having a charging roller 50 as a charging means and a cleaning blade 58a as a cleaning means is also integrally connected. The process cartridge is configured to be attachable / detachable to / from an image forming apparatus body such as a printer.

[0022]

According to the first aspect of the invention, even if the developer receives a frictional force from the wall surface at the end portion of the toner replenishing path, it is possible to ensure the same circulation state of the developer as in the other portions.
The predetermined toner is taken in. Therefore, without being affected by the wall surface at the end of the toner supply path,
There is an effect that it is possible to uniformly take in toner in the width direction. According to the second aspect of the present invention, even if the developer receives a frictional force from the wall surface at the end portion of the developer accommodating portion, it is possible to secure the same conveying force for the developer as in the other portions, and the location in the developing area can be secured. A fixed amount of developer comes to be conveyed. Therefore, there is an effect that the developer can be uniformly supplied to the developing area in the same width direction without being affected by the wall surface at the end of the developer accommodating portion.

[Brief description of drawings]

FIG. 1 is an enlarged cross-sectional view of a main part of a developing device of a printer according to an embodiment of the invention.

FIG. 2 is a front view showing a schematic configuration of the printer.

FIG. 3 is a partial perspective view showing an internal structure of a toner supply path end portion in a developing device used in the printer.

FIG. 4 is an explanatory view showing dimensions and angles under various conditions in the developing device.

FIG. 5 is a schematic configuration diagram showing a configuration example of a process cartridge.

[Explanation of symbols]

1 photoconductor drum 2 Development device 2a casing 3 developer 3a toner 4 Development sleeve 5 magnet roller 6 Doctor 7 developer storage case 7a Predoctor 8 toner hopper 8a Toner supply path 9 Toner agitator 11 Peeling roller (magnetic material) 20 Wall of casing 30 Developer Retaining Portion in Toner Supply Route 31 developer circulating section in toner supply path 50 charging roller 51 optical writing unit 52 sheets 53 Transfer roller 58 Cleaning device 58a cleaning blade 100 process cartridges S developer container

Claims (5)

[Claims] 1. A developer carrying member which has magnetic field generating means inside and which moves on the surface so as to carry and convey a developer containing a toner and a magnetic carrier, and a developing region carried by the developer carrying member. For regulating the amount of the developer conveyed toward the first
Developer regulating member, a developer accommodating portion for accommodating the developer blocked by the first developer regulating member, and an upstream side of the developer accommodating portion in the developer conveying direction on the developer carrier. And a second developer regulating member that regulates the amount of the developer carried and carried on the developer carrying body, and an upstream side of the second developer regulating member in the developer carrying direction on the developer carrying body. And a toner storage portion having a toner replenishment path that is adjacent to the above-mentioned toner and comes into contact with the developer carried and conveyed by the developer carrier or the developer blocked by the second developer regulating member. And a second developing unit for controlling the increase in the layer thickness of the developer existing in the toner replenishment path as the toner concentration of the developer on the developer carrier increases. A gap between the developer regulating member and the surface of the developer carrying member is set,
In a developing device in which the toner in the toner containing portion is taken into the developer by the movement of the developer in the toner replenishing path, the magnetic field generating means is located at a position facing the toner replenishing path.
A magnetic pole for taking in toner, which extends in a width direction orthogonal to the developer carrying direction on the developer carrying body, has a peak in the normal direction on the surface of the developer carrying body due to the magnetic pole for taking up toner. The value of the magnetic flux density at the end of the magnetic pole in the width direction is larger than the average value of the peak magnetic flux density in the normal direction in the portion in which the magnetic pole extends in the width direction. Developing device. 2. A developer carrying member which has magnetic field generating means inside and which moves on the surface so as to carry and convey a developer containing a toner and a magnetic carrier, and a developing region carried by the developer carrying member. For regulating the amount of the developer conveyed toward the first
Developer regulating member, a developer accommodating portion for accommodating the developer blocked by the first developer regulating member, and an upstream side of the developer accommodating portion in the developer conveying direction on the developer carrier. And a second developer regulating member that regulates the amount of the developer carried and carried on the developer carrying body, and an upstream side of the second developer regulating member in the developer carrying direction on the developer carrying body. And a toner storage portion having a toner replenishment path that is adjacent to the above-mentioned toner and comes into contact with the developer carried and conveyed by the developer carrier or the developer blocked by the second developer regulating member. And a second developing unit for controlling the increase in the layer thickness of the developer existing in the toner replenishment path as the toner concentration of the developer on the developer carrier increases. A gap between the developer regulating member and the surface of the developer carrying member is set,
In a developing device in which the toner in the toner containing section is taken into the developer by the movement of the developer existing in the toner replenishing path, the magnetic field generating means is located at a position facing the developer containing section.
A developer carrying and stirring magnetic pole extending in a width direction orthogonal to the developer carrying direction on the developer carrying body, and a normal line on the surface of the developer carrying body by the developer carrying and stirring magnetic pole. The value of the direction peak magnetic flux density at the end portion of the magnetic pole in the width direction is larger than the average value of the normal direction peak magnetic flux density in the portion in which the magnetic pole extends in the width direction. Characteristic developing device. 3. The developing device according to claim 1, wherein at least one of the developers which is in contact with or close to the surface of the developer carrier in the developer accommodating portion and is carried and carried by the developer carrier. A developing device comprising a peeling member for peeling off a portion. 4. A process cartridge comprising a latent image carrier and a developing device for developing a latent image on the latent image carrier to form a toner image, wherein the developing device is a developing device. A process cartridge including the developing device. 5. A latent image carrier, a latent image forming means for forming a latent image on the latent image carrier, and a developing device for developing the latent image on the latent image carrier to form a toner image. An image forming apparatus comprising a transfer device for transferring a toner image on the latent image carrier to a transfer material, wherein the developing device comprises the developing device according to claim 1, 2 or 3. Forming equipment.