JP3436337B2 - Developing device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing device of an image forming apparatus such as a copying machine, a facsimile, a printer,
Specifically, the latent image carrier and the developer are provided from the inside of a developing container by a rotating developer carrier and a magnetic field generating means for magnetically carrying a developer composed of toner and magnetic particles on the surface of the developer carrier. The present invention relates to a developing device that conveys a developer to a developing area facing a carrier to develop a latent image formed on the latent image carrier.

[0002]

2. Description of the Related Art Conventionally, as a developing device of this type, a developer regulating member for confronting the surface of the developer carrying member in the developing container and regulating a developer layer carried on the surface of the developer carrying member, A substantial immovable layer as a developer accommodating portion mainly containing the magnetic particles is formed over the upstream side in the rotation direction of the developer carrying member, and the developer is further provided on the upstream side of the immovable layer in the same rotation direction. It has been proposed that the toner particles are incorporated into the developer carried by the carrier (see, for example, JP-A-63-225266).

In this developing device, the size of the toner particle intake region is automatically increased or decreased by adding or detaching the magnetic particles to or from the immobile layer. Specifically, when there are a large number of magnetic particles present in the immovable layer, the size of the toner particle intake region decreases, and the amount of new toner taken into the developer that contributes to development decreases. On the other hand, when the amount of the magnetic particles existing in the immovable layer becomes small, the toner particle intake area increases and a large amount of toner is taken in. Thereby, the mixing ratio of the magnetic particles and the toner particles in the developer layer is automatically controlled. According to this type of developing device, long-term toner concentration control is automatically performed without providing a special mechanism for detecting the toner concentration in the developer and controlling the toner concentration based on the detection result. It can be carried out.

Further, the present applicant has previously proposed that a developer regulating member for regulating the amount of the developer carried on the developer carrying member and conveyed to the developing area, and the developer blocked by the developer regulating member. A developer holding member, which is arranged to face the surface of the developer carrying member with a predetermined gap, in order to form a staying developer holding portion, and a developer carrying direction of the developer carrying member on the developer carrying member in the developer holding portion. A toner accommodating portion that is adjacent from the upstream side and has a toner replenishing opening portion that faces the developer carrying member, and the toner that is taken into the developer retaining portion through the toner replenishing opening portion has a maximum toner concentration In such a state, the developer layer above the interface between the developer layers formed in the developer retaining portion and having different behaviors moves in a direction opposite to the conveying direction of the developer layer on the developer carrier. A developing device with a possible space Are draft (for example, Japanese Patent Application No. 7-1
19339). According to this type of developing device, the volume of the developer moving layer that rotates along with the rotation of the developer carrying member changes according to the state of taking toner into the magnetic particles,
As the toner is taken in by the magnetic particles, the developer moving layer swells so as to close the toner replenishing opening, so that the upper limit of the amount of toner taken in by the magnetic particles is determined, and the toner concentration does not exceed the upper limit concentration. . Therefore,
By presetting the amount of magnetic particles retained in the developer retaining portion, the toner concentration can be automatically controlled.

Further, the applicant of the present invention previously has an opening for communicating the inside of the main body of the developing device accommodating the developer carrying member and an opening / closing means capable of opening and closing the opening. It has been proposed that the developer accommodating portion is composed of a developer accommodating container that is detachable from the main body (Japanese Patent Application No. 7-11934).
(See No. 0). According to this structure, the opening / closing means provided in the opening of the developer container closes the opening, and thus the developer in the developer container where most of the developer in the apparatus exists is recovered. Further, the developer can be easily replaced by detaching the developer container from the developer body.

FIG. 8 shows a general developing device using a developer carrying member for carrying the developer by magnetic force, in which the magnetic force distribution a in the longitudinal direction of the developer carrying member and the developer carrying member are carried. The distributions b and c of the developer amount per unit area and the distributions d and e of the magnetic particle amount per unit length in the rotation direction of the developer carrier in the longitudinal direction of the developer carrier. is there. In order to make the magnetic force carrying force of the developer by the developer carrying member uniform, it is desirable that the magnetic force distribution in the longitudinal direction of the developer carrying member is uniform.
However, in the conventional developer carrier, as shown by the magnetic force distribution a in FIG. 8, the length Lm in the longitudinal direction is inside.
The magnetic force distribution of the magnet roller as the magnetic field generating means extending in step 1 is almost uniform in the central portion and in the vicinity thereof, whereas the magnetic force is strong at both ends because the magnetic field is strong. Therefore, in order to obtain a uniform magnetic force bearing force over the entire image width, the length Lm of the magnet roller is made sufficiently long so that the formed image width fits in the vicinity of the central portion where the magnetic roller magnetic force distribution is uniform. Is ideal. However, in order to adopt this ideal type, the size of the apparatus becomes large. Therefore, the ideal type cannot be taken, and the part where the magnetic force at both ends of the magnet roller is strong enters the image width or the image width The structure is adopted so as to approach both ends.

In the developing device having this structure, the magnetic particle carrying capacity is enhanced at the end of the magnet roller where the magnetic force is stronger, and the magnetic force is stronger each time the magnetic particles on the developer carrying member pass through the developing area. It moves to both ends of the developer carrier. For example, as shown by the distribution d of the amount of magnetic particles in FIG. 8, the magnetic particles that are uniformly carried over the entire area of the developer carrying member gradually move to the one having a stronger magnetic force while being conveyed. As a result, the unit length of the developer carrier is biased toward both end sides h of the developer carrier as shown by the magnetic particle amount distribution e in FIG. 8, and in the portion 1 near both ends adjacent to the center of the developer carrier. The amount of the magnetic particles carried in the developer conveying direction per unit time is reduced.

Such a decrease in the amount of the magnetic particles carried in the upper portion near the end portion of the developer carrying member is caused by the above-mentioned JP-A-63-2252.
In the case of a developing device for automatically controlling toner concentration as disclosed in Japanese Patent No. 66, in the portion 1 on the developer carrying member where this reduction occurs, the portion in the moving layer within the moving layer is operated from the principle of toner concentration self-control described above. The amount of toner taken into the developer increases. Further, even when it occurs in the developing device proposed in the above-mentioned Japanese Patent Application No. 7-119340, the amount of toner taken into the developer retaining portion becomes large in the portion 1 on the developer carrying member. Therefore, in any of the developing devices that automatically control the toner density as described above, the toner density increases near the both ends of the image.

Further, FIG. 7 is a view showing the arrangement of the developer carrier 4 and the developer regulating member 6 which have been conventionally proposed. As shown in this figure, the developer passing through the gap between the surface of the developer carrying member 4 and the developer regulating member 6 provided at a predetermined distance from the surface of the developer carrying member is upstream in the developer conveying direction. The width Wd that can exist in the developing device is regulated by a side seal (not shown) disposed on the side. Therefore, the amount of the developer per unit area on the developer carrying member is regulated by the developer regulating member 6 substantially uniformly from the surface of the developer carrying member to a thickness of, for example, 0.04 g / cm 2, and the developer regulating member and the developing member As shown in the developer amount distribution b in FIG. 8, the developer when passing through the gap with the agent carrier is
The width Wd is distributed.

Immediately after the passage, however, as shown by the developer amount distribution c in FIG. 8, the developer spreads to both sides of the width Wd and is carried in the vicinity of both widthwise end portions of the developer carrying member. The amount of magnetic particles per unit width is reduced. When the influence of the magnetic force of the magnet roller inside the developer carrying member is added, the amount of magnetic particles in the portion where the carrying amount of the developer carrying member is decreased is the end of the developer carrying member (h in FIG. 8). (Shown by 1), the amount of magnetic particles carried in the vicinity of the end portion (shown by 1 in FIG. 8) adjacent to the center side is further reduced. Therefore, due to the above-mentioned principle of self-control of toner concentration, the toner concentration becomes high in the vicinity of both ends of the developer carrying member.

Further, the developer whose strength at both ends of the magnet roller is strong and whose width Wd that can exist in the developing device is regulated by the side seals is the developer regulating member and the developer. After passing through the gap with the carrier, the toner spreads on both sides immediately after that, so that the toner concentration tends to increase in the vicinity of both ends of the developer carrier, and in general, the toner concentration increases. Near the edge,
Since the ratio of forming an image is remarkably low as compared with the central portion side and the toner consumption amount is small, the toner density is likely to increase.

[0012]

The present invention has been made in view of the above problems, and its object is to:
In a developing device having an automatic toner density control mechanism,
Suppress toner concentration increase of the developer carried on the developer carrier by the magnetic force and conveyed to the developing area in the vicinity of the end of the developer carrier, and cause toner scattering near the end of the developer carrier It is an object of the present invention to provide a developing device that does not cause contamination inside the device, scumming of a formed image, density unevenness on an image, and the like.

In order to prevent the developer layer on the surface of the developer carrier from being biased to one side or partly falling off when the entire developing device having the mechanism for controlling the toner density is tilted. Development in which the developer in the developer accommodating portion is packed with the surface of the developer carrier to keep the toner concentration of the developer layer on the surface of the developer carrier constant in the longitudinal direction of the developer carrier. A device has also been proposed (for example, Japanese Patent Laid-Open No. 64-105975). However, in this developing device, the magnetic field generating means extending in the longitudinal direction, which is provided inside the developer carrying member for carrying the developer by magnetic force, has a strong magnetic force at both ends as compared with the central part side. And that the developer whose width that can exist in the developing device is regulated by the side seals spreads to both sides immediately after passing through the gap between the developer regulating member and the developer carrier, Since the toner concentration is likely to be high near both ends of the carrier, there is no mention of suppressing the toner concentration increase that occurs near both ends in the longitudinal direction of the developer transport member as described above.

[0014]

In order to achieve the above object, the developing device according to claim 1 or 2 is a two-component developer containing a toner and magnetic particles on a developer carrying member having a magnetic field generating means inside. After the developer in the developer accommodating portion storing the developer is magnetically carried and the amount of the developer carried on the developer carrying member is regulated by passing through the gap with the developer regulating member, the developer is rotated. The developer is conveyed to a developing area facing the latent image carrier of the image forming apparatus, and is communicated with the developer accommodating portion through the toner intake opening so as to be in contact with the developer on the developer carrier. In the developing device that takes in the toner in the toner containing portion by the movement of the developer, the toner takeable amount of the toner taken in from the toner containing portion into the developer containing portion is the width direction of the developer carrying body. Such that less than the central portion side end portion, the toner uptake opening, the developing ZaiOsamu
It is characterized in that it is formed shorter than the width of the container portion . The developer accommodating apparatus according to claim 1 or 2,
From the toner intake opening that is narrower than the width direction of the
By supplying toner into the developer in the developer container,
The toner supply amount near the edge of the developer carrier
Reduce from the side. This makes it possible to
If the amount of toner consumed is less than that in the center,
When the magnetic bearing force at both ends of the
Even if the toner concentration is likely to increase, the developer carrier
The amount of toner supplied to the edges is reduced from the center side.
The toner density may rise abnormally near the edge.
And prevent. Particularly, the developing device according to claim 2 is the developing device according to claim 1.
In the developing device of the
Existing magnetic field generating means of length Lm and width of developer carrier
And a toner intake opening having a length Wt with respect to the direction,
If the length Wt is Wt
<Lm and toner in the width direction of the developer carrying member
The both ends of the intake opening are more than the both ends of the magnetic field generating means.
The toner intake opening formed so that it is located on the center side as well.
It is characterized by being configured with a mouth portion. Claim 2
In the developing device, the both ends in the longitudinal direction of the magnetic field generating means
Toner intake opening that is only open to the center side
Toner is supplied from the mouth into the developer in the developer container.
As a result, the magnetic force carrying force at both ends of the magnetic field generation means
Because it is stronger than the part, it is adjacent to both ends
The magnetic particles move from the side to the end and the magnetic particles decrease,
Both of the magnetic field generation means where the toner density is likely to rise
The amount of toner supplied to the vicinity of the edge is reduced.

[0015]

[0016]

[0017]

[0018]

[0019]

[0020]

[0021]

[0022]

[0023]

[0024]

[0025]

[0026]

[0027]

[0028]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment in which the present invention is applied to a developing device used in an electrophotographic copying machine (hereinafter referred to as "copying machine") which is an image forming apparatus will be described. FIG. 1A is a partial cross-sectional view showing the schematic configuration of the developing device according to the present embodiment. This developing device is disposed laterally of a cylindrical photosensitive drum 1 which is a latent image carrier used in an image forming apparatus, and a developing device case 2 having an opening formed toward the photosensitive drum 1, The developing sleeve 4 as a developer carrying member carrying a developer 3 composed of toner and magnetic particles (hereinafter referred to as "carrier"), a part of which is exposed from the opening, is fixedly arranged inside the developing sleeve 4. A magnet roller 5 composed of a fixed magnet group as a magnetic field generating means, a doctor 6 as a developer regulating member for regulating the amount of the developer 3 carried on the developing sleeve 4 and conveyed,
The developing sleeve 4 has an opening facing the sleeve, and the sleeve 4
A developer accommodating portion A, which is an accommodating space for the developer staying upward
The agent storage chamber forming member 7 for forming the Further, a toner hopper 8 as a toner storage portion is formed in a portion of the developing device case 2 opposite to the photoconductor 1 with the developing sleeve 4 interposed therebetween.

The inner surface of the side wall of the agent accommodating chamber forming member 7 has a predetermined distance from the surface of the developing sleeve 4, and the developing position of the portion facing the photoconductor drum 1 with the developing sleeve 4. A developer storage portion A for storing the developer that has not been supplied to the doctor 6 and is prevented from advancing by the doctor 6 is formed. The magnetic pole of the magnet roller 5 is arranged inside the developing sleeve 4 facing the developer accommodating portion A. The lower edge of the front doctor-side hispanic portion 7a, which is the side wall portion that extends like a canopy from the vicinity of the doctor 6 and is bent downward so as to partition the developer accommodating portion A from the inside of the toner hopper 8, is formed by the toner hopper 8 It opposes the bottom of the developer case 2 which is bulged upward to form a partition on the side of the developing sleeve 4 with a predetermined gap. A gap between the lower edge and the bottom portion is a toner supply opening 8a of the toner hopper 8 that is adjacent to the upstream side of the developer accommodating portion A in the developer transport direction and faces the surface of the developing sleeve 4. In the toner hopper 8,
In the space adjacent to the toner supply opening 8a, an agitator 9 as a toner sending member for sending the toner to the toner supply opening 8a while stirring is provided.

As shown in FIG. 1A, the agitator 9 in the illustrated example has a shaft portion 9a having a square cross section in the toner delivery direction at a position adjacent to the toner supply opening 8a in the hopper 8. Provided parallel to the width direction of the shaft portion 9a
On the two parallel sides facing each other, so as to extend straight by a certain width on the downstream side in the rotation direction of the shaft portion 9a.
A plate-shaped member 9b formed of, for example, is provided. In this agitator, the plate-shaped member 9a agitates the toner in the hopper 8 as the shaft 9a rotates, and sends the toner to the developer accommodating portion side. Therefore, as the distance from the rotation center of the shaft portion 9a to the tip of the plate-shaped member 9a is longer to some extent, the ability to stir the toner is higher and the toner can be efficiently sent to the developer accommodating portion A side.

In the developing device having the above-mentioned structure, the developer 3 on the developing sleeve 4 is conveyed as the sleeve 4 rotates in the direction of the arrow, 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 arrow direction. Then, in the developing area, toner is supplied to the electrostatic latent image formed on the photosensitive drum 1, and the electrostatic latent image is visualized. Developer 3 not used for this visualization
Is conveyed with the rotation of the developing sleeve 4 and takes in the new toner supplied by the agitator 9 and supplied from the toner replenishing opening 8a, and then returns to the developer accommodating section A.

In the developer accommodating portion A where the developer 3 having taken in the new toner from the hopper 8 has returned, the doctor 6
Internal pressure of the developer caused by the regulation of
Toner dispersion and toner charging are performed. As described above, since the toner in the developer 3 on the developing sleeve 4 can be charged by the increase in the internal pressure of the developer in the developer accommodating portion A, the developer 3 such as a paddle or a screw can be charged or stirred. No complicated stirring mechanism is required.

On the other hand, a part of the developer 3 which is not supplied to the developing area and whose progress is blocked by the doctor 6 is replenished with toner in the toner hopper 8 by the internal pressure and gravity of the developer 3 itself in the developer container A. It moves toward the opening 8a. The developer 3 that has moved to the vicinity of the toner supply opening 8 a is conveyed so as to circulate to the doctor 6 side as the developing sleeve 4 rotates.

FIGS. 2A to 2C show the moving state of the developer 3 in the developer accommodating portion A described above. A part of the developer 3 that is conveyed to the downstream side in the rotation direction of the developing sleeve 4 so as to hit the doctor 6 flows above the developing sleeve 4 toward the front doctor's hysteresis 7a, and rotates in the developer accommodating portion A. Start to do dynamic movements. This rotational movement is performed at a speed of 200 frames / sec.
It can be observed by taking a picture at about 0x speed.

The toner in the toner hopper 8 is as shown in FIG.
Confluence point c between the flow indicated by symbol a and the flow indicated by symbol b
It is taken into the developer from the vicinity. At this time, the developer is moving in the vicinity of the surface of the developing sleeve 4 at a rate of about 100 mm / sec, and since there is still a sufficient space in the developer accommodating portion A, the rotation of the developer retention layer is prevented. Speed is about 10mm
/ Sec.

FIG. 2B shows a state in which the toner intake is started. When the toner concentration and the developer volume gradually increase as the toner is taken into the carrier, the developer moving layer expands, the confluence point c gradually moves away from the vicinity of the surface of the developing sleeve 4, and the surface of the developing sleeve 4 increases. The flow velocity a of the developer in the vicinity also decreases. At this time, the developer 3 is moving near the surface at a speed of about 65 mm / sec, and the rotation speed of the developer retention layer is about 5 mm / s.
ec.

Then, as shown in FIG. 2C, the developer 3
When the amount of toner replenished to the developer increases and the toner concentration increases, the bulk of the developer 3 increases, and when the voids disappear in the developer accommodating portion A, the fluidity of the developer 3 gradually deteriorates. For this reason, as the developer moving layer expands, the confluence point c approaches the lower end of the front doctor doctor's desk portion 7a.
As a result, the toner is no longer taken into the developer 3. At this time, the rotation speed of the developer retention layer is about 1 mm /
It is sec. However, in the developer retention layer, there is a portion where the developer is still retained in a loosely packed state, the developer 3 in this portion has a relatively high toner content as compared with the other portions, and the flow velocity is very slow. However, the rotational movement continues, in which the dispersion of toner in the developer and the start-up of charging are in progress.

Then, the toner is consumed by the development,
When the toner density in the developer accommodating portion A decreases and the bulk of the developer 3 decreases, the state returns to the state of FIG. 2A, so that the toner intake into the developer starts again. At this time, not only the toner newly captured in the developer,
As described above, toner that is dispersed in the developer while rotating in the developer accommodating portion A and has a rising charge is naturally conveyed to the developing area, so that a large amount of toner is used for development. Even when a large amount of toner is taken into the developer, as in the device described in Japanese Patent Publication No. 5-67233, the background charge or toner scattering may be severe due to insufficient charging of the toner. Problems are less likely to occur.

By the above operation, the toner density of the developer 3 is kept within a certain density range. Since the toner concentration can be controlled in this way, a complicated toner concentration control mechanism using a toner concentration sensor, a toner replenishing member, etc. is not required.

The developing device of this embodiment employs a structure for facilitating the work of setting the developer on the developing device. That is, as shown in FIG. 1A, the agent storage chamber forming member 7 in this developing device is
A carrier is housed inside, and a seal 11 serving as a shutter member is configured to be detachable so that it can be set in the developing device main body in a state where the opening for communicating the inside of the developer housing A and the developing device main body is closed. Has been done. The seal 11
As shown in FIG. 1 (c), the upper end 11a is adhered to the upper surface of the agent storage chamber forming member, and extends from the portion facing the doctor 6 to the lower edge of the opening so as to cover the entire opening. After being ejected, it is folded back to the developer accommodating portion A side, and at this folded back portion 11b, it is adhered to the lower end portion of the front doctor's knee 7a corresponding to the lower end edge of the opening portion. The upper end of the folded back portion is bonded to the agent storage chamber forming member portion corresponding to the upper edge of the opening. The seal 11 has an upper end 11a.
Is opened from the surface of the agent-accommodating chamber forming member and pulled upward to open the opening.

When a new carrier is stored in the developer accommodating portion A using the above-mentioned agent accommodating chamber forming member 7, the opening is closed by the seal 11 with the new developer already inside. The agent accommodating chamber forming member 7 is attached to the developing device main body as it is. And the seal 1
1 is pulled out upward to open the opening, and the containing carrier is caused to flow down onto the developing sleeve 1 by its own weight to supply the carrier. This completes the carrier supply work, so that the work can be performed easily.

FIG. 1 (d) is a perspective view of the agent accommodating chamber forming member 7 in which the opening is closed by the seal 11 in a state in which a new developer is previously contained. This figure shows a state in which the seal member 11 is partially broken.
Reference numeral 7b is an end wall portion, and reference numeral 14 is a side seal provided on the surface of the end wall portion facing the developing sleeve.

In the developing device of this embodiment,
A structure is also adopted which can prevent the toner density near the edge of the formed image in the width direction from becoming higher than a desired density.
3A to 3C are cross-sectional views of the vicinity of the agitator end of the developing device according to the present embodiment, and the toner replenishing opening 8.
It is a front view of a. In these drawings, the front of the doctor 7 of the toner replenishment opening 8a extending to the side wall 14 is shown.
The gap between the lower edge of the a and the developer case 2 is formed in two stages, and the gap is widened in the central portion of the toner supply opening 8a.
1, G2 is narrowed at both ends. Specifically, FIG.
As shown in (c), the toner replenishment amount regulating means is constructed by extending the lower end portion of the doctor front heap portion 7a downward only at the portion forming the narrow gap G2 near the end portion of the toner replenishment opening 8a. It is close to the upper end of the case 2. Further, as shown in FIGS. 3 (a) and 3 (b), the plate-shaped member 9a (see FIGS. 1 (a) and 1 (b)) provided near the center of the agitator 9 is removed in the vicinity of the end. ing.

In this structure, as shown in FIG. 3A, the agent accommodating chamber forming member 7 in which the carrier is accommodated inside and the opening of the developer accommodating portion A is closed by the seal 11 is provided in the apparatus main body. After mounting, seal 11 as shown in FIG.
Is pulled out upward, the opening of the developer accommodating portion A is opened, and the carrier is supplied. Then, the agitator 9 rotates. Near the end of the agitator 9, the shaft 9a having a square cross section is formed.
Since the outermost peripheral locus 13 formed by the end portion of the toner is much smaller than the portion having the plate-shaped member 9a near the central portion, the amount of toner sent to the developer accommodating portion A is near the central portion. It decreases in comparison. Further, the amount of toner that can be taken into the developer accommodating portion A from the toner hopper 8 through the toner supply opening 8a depends on the width of the gap, and the amount of toner that can be taken in from the vicinity of the end of the toner supply opening 8a. Since the gap is narrowed so that the amount of toner becomes smaller than that of the central portion, the developer accommodating portion A can be more reliably
The amount of toner sent to the printer is reduced as compared with the vicinity of the central portion.

According to the above construction, the locus drawn by the tip of the agitator 9 is reduced by the rotation of the agitator 9 in the vicinity of both ends in the longitudinal direction of the agitator 9, so that the developer accommodating portion A is rotated by the rotation of the agitator 9. The amount of toner that can be sent to the side can be reduced in the vicinity of both ends in the longitudinal direction of the agitator 9 compared to the vicinity of the central portion. Further, since the gap near the end of the toner supply opening 8a is narrowed, it is possible to more reliably reduce the amount of toner sent to the developer accommodating portion A in the vicinity of the end as compared to the central portion. You can As a result, when the toner consumption amount is smaller than that in the central portion side, or when the carrier moves to a portion where the magnetic force is strong at both ends of the magnet roller 5, the carrier decreases on the inner side adjacent thereto. In some cases, it is possible to prevent the toner concentration from increasing near the both ends of the developing sleeve 4 where the toner concentration tends to increase. Further, it is possible to prevent the toner scattering, the inside of the apparatus, the background stain of the formed image, and the density unevenness on the image, which are caused by the toner concentration increase near the end portion of the developing sleeve 4. The amount of toner that can be replenished in the developer accommodating portion A depends on whether the shaft member 9a of the agitator 9 is provided with the plate member 9a or whether the gap of the toner replenishing opening 8a is widened or narrowed. The adjustment can be performed in the width direction of the developer accommodating portion A, and the configuration is easy. In the illustrated apparatus example, the range of the gap G1 on the central side of the toner supply opening 8a is preferably 1 mm≤G1≤5 mm.

FIGS. 4A to 4C are a sectional view of the vicinity of the end portion of the agitator 9 of the developing device according to the modified example of the present embodiment, and a front view of the toner supply opening 8a. In this example, an elastic member 12 as a toner replenishment amount regulating means is provided only at the upper end portions of the developing device case 2 near both ends of the toner replenishment opening 8a, and the elastic member 12 and the lower end portions of the doctor's front histopic portion 7a. And a narrow gap G2 is formed. Further, the shape of the agitator 9 is as shown in FIG.
The configuration is similar to that of (c). With the above configuration, the same effects as those in FIGS. 3A to 3C can be obtained.

In the above two examples, the toner replenishment opening 8 is formed.
Since the amount of toner replenishment by the agitator 9 is limited near the end of a and the gap of the opening is narrowed at both ends, the toner replenishment near the end of the toner replenishing opening 8a is more effective. The amount can be reduced and a more preferable effect can be obtained.

On the other hand, the gap of the toner replenishing opening 8a is not narrowed at the same time as the gap of the toner replenishing opening 8a is narrowed in the vicinity of both ends, and the toner conveying ability of the agitator 9 is reduced near the both ends. Alternatively, only one of the plate-shaped members 9a of the agitator 9 may be configured so that the amount of taken-in toner is reduced at both ends of the toner supply opening 8a. As a result, the toner supply opening 8a
The configuration that reduces the amount of toner replenishment in the vicinity of the end portion of is easy.

Further, the toner replenishing opening 8a does not extend to the side wall of the apparatus and is made short in the width direction, so that the toner concentration increase in the vicinity of the end portion in the width direction of the formed image can be prevented. For this purpose, for example, the doctor's front histograph portion 7 in which the gap G2 in the configuration example of FIG.
The lower end of “a” may be set, or the height of the elastic member 12 in the example of FIG. 4C may be set.

FIG. 5A shows the toner replenishing opening 8a in the example of the apparatus in which the toner replenishing opening 8a is opened as described above.
It is a figure showing the width Wt and the widths of other members to be compared. In this figure, the length of the magnet roller 5 in the longitudinal direction is represented by Lm, and the developer accommodating portion A in the same direction, the distribution of the developer passing through the doctor facing portion, the image area,
Further, the widthwise length of the toner supply opening 8a is represented by Wz, Wd, Wa, and Wt, respectively. Here, in general, the magnet roller 5 provided in the developing sleeve 4 is used.
The length Lm in the longitudinal direction is set to about 10 mm or more with respect to the width Wa of the image area in order to prevent the rapidly changing magnetic field at the end of the magnet roller 5 from affecting the area of the formed image. Since this is generally done, this is also done in this device example. Further, the width Wz of the developer accommodating portion A is set within the range in which the magnetic force carrying force of the magnet roller 5 is uniformly guaranteed and is longer than the image area width Wa so that the developer is uniform in the developing area in the width direction. Since it is generally possible to supply a uniform amount by carrying a magnetic force, this is done also in this device example.

In the apparatus example of FIG. 5A, the width Wt of the toner replenishing opening 8a is formed shorter than the length Lm of the magnet roller 5, and the magnet roller 5
Both end portions of the toner supply opening 8a are located closer to the central portion than both end portions thereof. Here, the inventors of the present invention set the width Wt of the toner supply opening 8a to the magnet roller 5
As a result of investigating how effective it is to shorten from both ends of each, 10 mm from each end of the magnet roller 5
It has been found that it is preferable to shorten it to some extent. However,
This numerical value is not a value that can be uniformly determined for every device because there is a difference in the magnetic field distribution of the developing main magnetic pole of the developing roller. In general, it is preferable to set the extent that the range of the influence of the high magnetic force due to the high magnetic gradient at the end portion of the magnet roller 5 can be avoided as shown by the magnetic force distribution a in FIG.

With the above structure, the amount of toner supplied to the vicinity of both ends of the magnet roller 5 is reduced, so that the magnetic bearing force at both ends of the magnet roller 5 is adjacent to the inside where the magnetic bearing force is stronger than the other portions. Even when the carrier moves from (hereinafter, referred to as an adjacent portion) and the carrier on the developing sleeve 4 in the adjacent portion decreases, it is possible to prevent the toner concentration in the adjacent portion from abnormally increasing, and to prevent the toner concentration in the vicinity of the adjacent portion from increasing. It is possible to prevent the toner scattering, the inside of the apparatus, the background stain of the formed image, and the density unevenness on the image, which are caused by the increase of the toner concentration on the developing sleeve 4.

Further, in the apparatus example of FIG. 5A, the width Wt of the toner replenishing opening 8a is set to the developer accommodating portion A.
The width Wz is shorter at both ends. Figure 6
FIG. 6 is a diagram showing a configuration example for forming the width of the toner supply opening 8a smaller than the width between the device side walls. In this figure, the width Wz of the developer accommodating portion A is regulated by the side wall of the apparatus, and the width between the developer accommodating portion A and the toner hopper 8 is set between the lower end of the developer accommodating container and the tip of the developing device case 2. The elastic member 12 is in a sealed state. An elongated toner replenishing opening 8a having a desired length between the side walls and a desired width in the vertical direction is formed on the upper portion of the front end 7a of the doctor's front knee 7 by a predetermined distance. In this figure, a metal net is provided in the toner supply opening 8a so that the toner density supplied from the toner supply opening 8a can be kept uniform in the longitudinal direction of the opening. In order to maintain a uniform width in the vertical direction of the toner supply opening 8a, punch metal, ribs or the like may be provided in the toner supply opening 8a. Here, as a result of investigations by the present inventors on how effective the width of the toner supply opening 8a is with respect to the width between both ends of the developer accommodating portion A, the result is that the developer accommodating portion is It was found that it is better to shorten the length from both ends of A by about 2.5 to 5 mm. However, this numerical value is also not a value that can be uniformly determined for every device because there is a magnetic field distribution difference of the developing main magnetic pole of the magnet roller 5. Further, in the present embodiment, the width Wt of the toner supply opening 8a is set to the width Wa of the image area.
Shorter than that. To make the width Wt of the toner supply opening 8a shorter than the width Wz of the developer accommodating portion A at both ends, as described above, for example, the height of the elastic member 12 in the example of FIG. Is set so that the width of the elastic member 12 is set to the developer accommodating portion A.
It may be set so as to extend beyond the thickness of the end wall of the agent-accommodating-chamber forming member 7 constituting the above, and reach the corresponding portion in the developing accommodating portion B. (Hereafter, margin)

According to the above construction, the toner is supplied into the developer in the developer accommodating portion A from the toner replenishing opening 8a having a width narrower than the width direction Wz of the developer accommodating portion A, and the developing sleeve 4 of Since the amount of toner supplied to the vicinity of the edges is decreased from the center side, the toner consumption is generally smaller than that of the center side, and the amount of toner supply to the vicinity of both ends of the image area where the toner density is likely to rise is It is possible to reduce the toner concentration from the side of the sheet, and it is possible to prevent the toner concentration from abnormally increasing near the edge.

FIG. 5B shows the width Wt of the toner replenishing opening 8a and the width of other members to be compared in another example of the apparatus in which the toner replenishing opening 8a is opened as described above. It is the figure which showed. Also in this drawing, the length in the longitudinal direction of the magnet roller 5, that is, the effective length of magnetization is represented by Lm, and the distribution of the developer passing through the developer accommodating portion A and the doctor facing portion in the same direction, the image area. (The largest in the width direction),
Further, the widthwise length of the toner supply opening 8a is represented by Wz, Wd, Wa, and Wt, respectively. In this device example, the three Lm, Wz, and Wd are the same. And, Wa is shorter than these, and further, this Wa
Wt is shorter than that. For example, three of Lm, Wz, and Wd are 304 mm, Wa is 297 mm, and Wt is 287 mm. Also with this device example, the effect corresponding to the same configuration portion as described with respect to the device example of FIG.

[0056]

According to the developing device of claims 1 and 2 , the present invention
Toner intake opening that is narrower than the width of the image storage unit
Section to supply toner into the developer in the developer containing section.
The amount of toner supplied near the edge of the developer carrier.
The toner concentration is likely to increase when the amount of toner consumption near the edge of the image area is smaller than that of the central portion, or when the magnetic force carrying force at both ends of the magnetic field generating means is stronger than that of the central portion. Even in this case, the amount of toner supplied to the vicinity of the end portion of the developer carrying member is reduced from the central portion side,
It is possible to prevent an abnormal increase in the toner concentration near the edge portion, and to prevent the toner from scattering due to the increase in the toner concentration near the edge portion of the developer carrying member, the inside of the apparatus, the background stain of the formed image, and the density on the image. There is an effect that the occurrence of unevenness can be prevented. Particularly, according to the developing device of claim 2, a magnetic field is generated.
The magnetic bearing force at both ends of the means is stronger than the other parts.
In order to magnetic particles from the inside adjacent to both ends to the end
The particles move, the magnetic particles decrease, and the toner concentration increases.
Toner near the ends of the magnetic field generator
Since the supply amount is reduced, the toner density near the edge is reduced.
Abnormal rise can be prevented, and the
Toner scattering due to increased toner concentration, inside the device
Contamination, background stains on the formed image, density unevenness on the image, etc.
There is an effect that can prevent.

[0057]

[0058]

[0059]

[0060]

[0061]

[Brief description of drawings]

FIG. 1A is a schematic configuration diagram of a developing device of an electrophotographic copying machine according to an embodiment in which an opening of a developer container is closed by a seal member. FIG. 2B is a schematic configuration diagram of the developing device of the electrophotographic copying machine in a state in which the opening of the developer container is opened. FIG. 6C is a vertical cross-sectional view of a seal provided in an opening that connects the inside of the developing container A and the developing device main body. (D)
[FIG. 6] is a perspective view of the agent storage chamber forming member 7.

FIG. 2A is an explanatory diagram showing a state before starting to take in toner into a carrier. FIG. 6B is an explanatory diagram showing a process of taking toner into a carrier. FIG. 7C is an explanatory diagram showing a state in which the toner has been taken into the carrier.

FIG. 3A is a schematic configuration diagram of an end portion of an agitator in a developing device of an electrophotographic copying machine according to an embodiment in which an opening of a developer container is closed by a seal member. (B) is
FIG. 3 is a schematic configuration diagram of an agitator end portion of the developing device of the electrophotographic copying machine in a state where an opening of a developer container is opened.
FIG. 6C is a front view of the toner supply opening portion.

FIG. 4A is a schematic configuration diagram of an end portion of an agitator in a developing device of an electrophotographic copying machine according to a modified example of the embodiment, in which an opening of a developer container is closed by a seal member.
FIG. 2B is a schematic configuration diagram of an end portion of the agitator of the developing device of the electrophotographic copying machine in a state where an opening of a developer container is opened. FIG. 6C is a front view of the toner supply opening portion.

FIG. 5A and FIG. 5B are explanatory diagrams comparing the width Wt of the toner supply opening and the width of each member in a specific device example.

FIG. 6 is a front view showing the configuration of a toner supply opening according to the present embodiment.

FIG. 7 is a diagram showing an arrangement of a developer carrier 4 and a developer regulating member 6 which have been proposed conventionally.

FIG. 8 is an explanatory diagram of a magnetic force distribution in the longitudinal direction of the developer carrying member, a developer amount distribution per unit area, and a magnetic particle amount distribution per unit length in the developer carrying member rotating direction.

[Explanation of symbols]

1 photoconductor drum 2 Support case 3 developer 4 Development sleeve 5 magnet roller 6 Doctor 7 Agent storage chamber forming member 7a The front of the doctor 8 toner hopper 8a Toner supply opening 9 agitator 12 Elastic member A developer container Lm Length of magnet roller in the longitudinal direction Wz Width of developer container Wd Doctor width Wa Image area width Wt Toner supply width

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yasushi Akiba 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Co., Ltd. (56) References JP-A-7-114259 (JP, A) JP-A 61-230176 (JP, A) JP-A-6-35314 (JP, A) Actual development 3-11258 (JP, U) (58) Fields investigated (Int.Cl. ⁷ , DB name) G03G 15/09 G03G 15/08 112 G03G 15/08 506 G03G 15/08 507

Claims (3)

(57) [Claims] 1. A developer regulating member, wherein a developer carrier in which a two-component developer containing toner and magnetic particles is stored is magnetically carried on a developer carrier having a magnetic field generating means therein, and a developer regulating member. After controlling the amount of the developer carried on the developer carrying member by passing through the gap between the developer and the developer, the developer is conveyed to the developing area facing the latent image carrying member of the image forming apparatus while rotating, and In a developing device that takes in the toner in the toner containing portion which is in communication with the developer containing portion through the toner intake opening and is stored so as to come into contact with the developer on the developer carrier, as the toner capturable amount of toner taken into the developer container from the housing portion, smaller than the central portion in the width direction near both ends of the developer carrying member, the toner
The intake opening is made shorter than the width of the developer container.
Developing apparatus is characterized in that the. 2. The developing device according to claim 1, wherein the developer accommodating portion has an opening for communicating the interior with a developing device main body accommodating a developer carrier, and a removable shutter for closing the opening. A developing device comprising a developer accommodating container having a member and detachably attached to the developing device main body. 3. The developing device according to claim 1 or 2, wherein a magnetic field generating means having a length Lm extending in the longitudinal direction inside the developer carrying member, and a toner W having a length Wt in the width direction of the developer carrying member. An opening portion, wherein the length Wt is Wt <Lm, and both ends of the toner intake opening portion in the width direction of the developer carrying member are closer to both ends than the magnetic field generating means. The developing device is also characterized in that the toner intake opening is formed so as to be located on the central side.