JP3164330B2 - 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 for an image forming apparatus.

[0002]

2. Description of the Related Art In an image forming apparatus such as a copying machine, a printer, a facsimile, and the like, in which an electrostatic latent image is formed on a latent image carrier, a so-called dry type is used in order to visualize the latent image. Developing devices are widely used. FIG. 15 shows a conventional example of such a developing device. The developing device 1 is provided to face a drum-shaped photoconductor 2 which is an example of a latent image carrier. The photoreceptor 2 is driven to rotate in a direction indicated by an arrow by a driving unit (not shown).

A two-component developer 4 having a toner and a carrier is contained in a developing container 3 of the developing device 1.
A developer carrying member 6 is provided in the developing container 3 so as to face the photoconductor 2 with a predetermined gap. The developer carrying member 6 is made of, for example, a non-magnetic sleeve and has a magnet body 8 having a plurality of magnetic poles provided therein. Hereinafter, the developer carrying member 6 is referred to as a “development sleeve” in accordance with this configuration example. In the developing device 1 shown in the figure, a developing sleeve 7 having the same configuration is provided below the developing sleeve 6, and both the developing sleeves 6 and 7 are driven to rotate in the directions indicated by arrows in the drawing. I have. A magnet (not shown) is also arranged inside the lower developing sleeve 7. The lower developing sleeve 7 is provided as needed, and may be omitted.

In the example of FIG. 15, the developing sleeves 6 and 7 are rotated, and the respective magnets 8 inside are fixed. However, the developing sleeves 6 and 7 are fixed and the respective magnets 8 inside are fixed. The present invention can also be applied to a developing device of a type in which the rotating members 8 are rotated or both of them are rotated.

[0005] A paddle wheel 5 provided in the developing container 3 rotates in the direction of the arrow shown in the figure to agitate the developer 4 in the developing container 3 and supply the developing agent 4 to the developing sleeves 6 and 7 while throwing the developer. I do. Now, paying attention to the upper developing sleeve 6, the developer supplied to the developing sleeve 6 is magnetically carried on the peripheral surface by the magnetic force of the magnet body 8,
Due to the rotation of the sleeve 6, it is transported in the direction of rotation.

A doctor blade 9 disposed on the upper side of the developing sleeve 6 in the drawing scrapes off and removes excess developer carried and conveyed on the developing sleeve 6 so that its layer thickness is suitable for development. Set to thickness. The developer whose layer thickness is regulated reaches the developing area 12 between the photoreceptor 2 and the developing sleeve 6, where it is used for developing the electrostatic latent image formed on the photoreceptor 2, The image is visualized as a toner image. The developer that has passed through the developing area 9 passes through a second developing area between the lower developing sleeve 7 and the photoconductor 2, and is again provided for visualization of the electrostatic latent image. Returned to 3. The doctor blade 9 is an example of a developer layer thickness regulating member that regulates the layer thickness of the developer supplied onto the developing sleeve 6 and pumped up before development.

A separator 13 is provided above the developing container 3 and above the paddle wheel 5 therein.
The separator 13 has a developer guide plate 14 facing the developing sleeve 6, and the developer pumped on the developing sleeve 6 passes between the developer guide plate 14 and the developing sleeve 6, Reaching the doctor blade 9, the doctor blade 9 scrapes off the excess.
The scraped developer is guided to the separator 13.

FIG. 16 is a schematic view of the separator 13 as viewed from above. The separator 13 has fins 15 arranged in an oblique position and a pair of parallel fins 16. A part of the developer guided to 13 passes between the fins 15 and flows down in the direction of arrow D as shown in FIG. While the developer passes between the fins 15, the developer is moved to the F side in FIG.

On the other hand, the developer that has passed between the parallel fins 16 is guided to a developer transport path 18, and a developer transport screw member 19 (FIG. 15) provided in the transport path 18, from the F side. It is sent to E side. And the opening 2 on the E side
1 and is returned into the developing container 3. The separator 13 includes a fin 15 and a developer conveying screw member 19.
The function of returning the developer into the developing container 3 while so-called lateral stirring is performed. That is, the function of returning the developer to the inside of the developing container 3 is performed so that the concentration of the toner in the developer becomes uniform in the axial direction of the developing sleeve 6.

In FIG. 15, if the amount of the developer directed to the doctor blade 9 is not sufficient, the powder pressure applied to the doctor blade 9 becomes insufficient, and It is not possible to determine an appropriate layer thickness, the image density is reduced, and the image quality is adversely affected. The developer guide plate portion 14 performs a guide function of guiding the pumped developer toward the doctor blade 9, but in the configuration shown in the drawing, the developer is accumulated in a G portion (wedge-shaped portion). In other words, the fluid flows smoothly without increasing the density, and it may not be possible to determine a favorable layer thickness.

On the other hand, in this type of developing device, when the developer is positively stirred while passing through the portion G, the toner and the carrier are satisfactorily triboelectrically charged. The occurrence of background dirt on the image can be suppressed. When the developer guide plate portion 14 has the above-described configuration, it is difficult to perform such stirring, and a part of the toner is insufficiently charged, and the background is easily stained. Tension may cause image quality to deteriorate.

As related to this type of technology, for example, Japanese Patent Application Laid-Open Nos.
No. 3 has already been proposed, but these developing devices also increase the density of the developer toward the doctor blade and improve the triboelectric charging of the toner and carrier of the developer before reaching the doctor blade. It was difficult to satisfy both functions simultaneously.

[0013]

SUMMARY OF THE INVENTION An object of the present invention is to provide a developer layer thickness regulating member with a view to further improving image quality.
It is an object of the present invention to provide a developing device capable of feeding a developer with a high density and a stirring state.

[0014]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a developer container for storing a developer, a developer carrying member for carrying the developer on a peripheral surface thereof, and a developing member. A developer layer thickness regulating member for regulating the layer thickness of the developer supplied on the developer carrying member before development, in a developing device of an image forming apparatus, the developer is applied to the developer layer thickness regulating member. A developer movement restricting member for stirring and moving while being accumulated before heading is provided so as to face the developer carrying and conveying member, and the developer movement restricting member is a space portion between the developer carrying and conveying member. And a vertical plate portion opposed to the developer-carrying / transporting member so that the vertical plate portion spreads in the developer-moving direction. And a protruding part protruding toward the member side. , The projecting portion proposes a developing apparatus is characterized in that protrude less than half the length of the distance between the developer carrying and transporting member and the vertical plate portion.

It is effective if the amount of protrusion of the projecting portion gradually increases from the center to both ends in the axial direction of the developer carrying member.

Further, it is effective that the vertical plate portion forms an obtuse angle with respect to the direction in which the protruding portion protrudes.

Further, it is effective that the developer movement regulating member is formed integrally with a separator for returning the developer removed by the developer layer thickness regulating member to the side of the developing container.

[0018]

[0019]

[0020]

Embodiments of the present invention will be described below in detail with reference to the drawings. In the drawings used in the following description, the same reference numerals are used for members that achieve the same functions as those in the conventional example, and descriptions of the configurations and functions are omitted for convenience.

In the developing device 11 shown in FIG. 1, a developing sleeve 6 which is an example of a configuration of a developer carrying and conveying member includes
A developer movement restricting member 24 is provided so as to face the drum-shaped photoconductor 2, which is an example of a latent image carrier, on the opposite side. The developer movement restricting member 24 is provided with the developer 4 pumped up by the developing sleeve 6 toward the doctor blade 9 which is an example of the configuration of the developer layer thickness restricting member.
Before moving toward the doctor blade 9, and acts to move while stirring.

As shown in FIG. 2, the developer movement restricting member 24 includes a vertical plate portion 25 facing the developing sleeve 6 and a developing plate from a downstream end of the vertical plate portion in the developer movement direction. A protrusion 26 projecting horizontally toward the side of the sleeve 6. In the case of this example, the developer movement restricting member 24 thus configured is formed integrally with the flat plate portion 27 of the separator 23 for returning the developer removed by the doctor blade 9 to the side of the developing container 3. It has become something. The developer scraped off by the doctor blade 9 passes between the doctor blade 9 and the protruding portion 26, and as shown in FIG.
And moves toward the fin portions 15 and 16 on the flat plate portion 27 shown in FIG.

In FIG. 1, the developer 4 supplied from the paddle wheel 5 toward between the developing sleeve 6 and the vertical plate portion 25 is applied by the magnetic force of the magnet body 8 to the developing sleeve 6.
The developing sleeve 6 is pumped on the developing sleeve 6 with the rotation of the developing sleeve 6, and the developing sleeve 6 and the vertical plate 25
Pass through.

The space between the developing sleeve 6 and the vertical plate portion 25 is widened in the direction of movement of the developer. A portion of the developer passing between the vertical plate portion 25 and the vertical plate portion 25 has a projecting portion 26 that acts as a damming member, so that the developer moves while collecting in the space. Further, the stirring flow 22 of the developer is generated.

If the developer moves toward the doctor blade 9 while accumulating, the powder pressure of the developer increases, the absolute amount of the developer toward the doctor blade 9 increases, and the density of the developer increases. become. In any case, the powder pressure of the developer, which is a powder, increases, so that the doctor blade 9 can regulate the layer thickness of the developer to a desired state, and furthermore, the density of the developer that has passed through the blade 9 Can be stabilized, and an image having a predetermined density can be obtained. Further, the function of the agitating flow 22 improves the triboelectric charging property between the toner and the carrier, so that the so-called charge rising characteristics of the developer are improved. This makes it difficult for the background to be stained on the image, and the image quality is improved. In this way, the developer transfer regulating member 24 can simultaneously satisfy the two requirements.

On the other hand, in the conventional apparatus shown in FIG. 15, the space G is gradually narrowed, so that the amount of the developer passing therethrough is also limited, and tends to be smaller. In addition, since the developer does not have an effect of blocking the developer and the developer moves smoothly, the above-described effects cannot be expected.

FIG. 9 shows the amount of toner supplied to the developer (the amount of toner supplied to the developer in the developing container 3),
This figure shows the correlation characteristic with the background dirt occurrence rank. FIG. 1 (I) shows the case of this example, and FIG. 2 (II) shows the case of the conventional example (FIG. 15).

In the case of the conventional example, in the case of a developer having a high toner concentration (two-dot chain line), background contamination is easily generated in the range of H. On the other hand, in the case of the present example, there is a tendency that background contamination is less likely to occur in that range.

When the developer movement restricting member 24 is formed integrally with the flat plate portion 27 of the separator 23 as in the embodiment shown in FIG. 1, the number of parts of the developing device can be reduced, the structure can be simplified, and the cost can be reduced. Is also advantageous.

When the main body of the image forming apparatus is placed at a predetermined place, the main body of the image forming apparatus tilts due to the inclination of the place where the main body of the image forming apparatus is tilted. is there. For example, as shown in FIG. 2, the developing device may be inclined so that the level of the portion e is higher than the portion a, assuming that the separator 23 is divided into the portions a to e. On the contrary, the developing device may be inclined such that the part a is higher than the part e. In this case, the higher the level,
There is a tendency that the amount of developer pumped up by the developing sleeve is smaller than that of the lower portion.

In this case, the conventional example (FIG. 1)
In the case of 5), a predetermined pumping amount may not be able to be secured at a portion where the pumping amount becomes high. (II) of FIG. 10 shows the correlation characteristic between the inclination amount of the developing device and the amount of the developer pumped up in the conventional example, and shows each part (a to e) when the e portion (FIG. 2) of the developing device is raised. The pumping amount of the developer in e) is as shown in the figure.

When the part e is raised by 5 to 8 mm, the amount of developer pumped at the part e tends to be particularly small. On the other hand, in the case of the present example (FIG. 1), as shown in FIG. 10 (I), the decrease in the pumping amount in the portion e is eliminated. In any case, according to the developing device of this example,
Even if there is a mechanical inclination (the inclination of the image forming apparatus body),
The amount of pumping can be given a margin, and a sufficient amount of
The high-density developer can be guided toward the doctor blade 9. The developer can be stored by the blocking action of the developer movement restricting member 24, so that even if the developing device 11 is slightly inclined, the amount of developer pumped can be prevented from being greatly reduced.

By the way, as shown in FIG. 17, a developing device in which the position Y of the separator 13 is lower than the position X of the lower end portion (blade tip) of the doctor blade 9 is conventionally known. In the case of such a developing device, when the developing device is tilted as described above, a quantitative balance is lost particularly in pumping up the developer. Even in the developing device having such a configuration, the use of the developer movement restricting member 24 as shown in FIG. 1 can provide a margin for the amount of developer pumped up. The developer can be pumped up stably.

Further, in the case of the conventional example shown in FIG. 15, the developer not passing through the doctor blade 9
In this case, if the absolute amount of the developer going to the separator is insufficient, the amount of the developer laterally agitated by the fins 15 and the developer conveying screw member 19 becomes small. As a result, the uniform dispersibility of the toner in the developer, that is, the mixing property of the developer cannot be improved.

Here, as shown in FIG.
The protruding length of 6 and L _1, the distance between the developing sleeve 6 and the vertical plate portion 25 (hereinafter, referred to as "separator gap") as those to be L _2, protruding length of the protruding portion 26 L ₁ Is set to １ ／ or less of the separator gap L _2, the amount of the developer returned to the separator 23 can be increased, and the mixing property of the developer can be prevented from being deteriorated. Further, it is possible to prevent the rotational load torque of the developing device from excessively increasing.

The longer the length L ₁ of the protrusion 26 is, the more the above-mentioned effect obtained by the developer movement restricting member 24 is enhanced, which contributes to the improvement of the charge-up property of the developer. When the length L ₁ becomes too large, fewer return amount of the developer to the separator 23 side, also,
The rotational load torque of the developing device may increase. In this case, the rotation driving motor of the developing device is overloaded, or the life of the developer is shortened. Projection 26
By making the protrusion length of 以下 or less of the separator gap, while eliminating such problems, the advantage of the developer movement restricting member 24 is utilized, and the density of the developer toward the doctor blade 9 is increased. In addition, the stirring flow 22 can be generated to enhance the triboelectric charging property between the toner and the carrier.

[0037] In this connection, FIG. 5, protruding length L _1, shows the correlation characteristics between the rotational load torque of the developing device according protruding length L ₁ is greater, the rotation load torque increases. Note that the solid line is a characteristic line when the separator gap L ₂ (FIG. 3) is 2.1 to 2.3 mm, and the dashed line is a characteristic line when the separator gap L ₂ is 3.0 mm.

Here, as shown in FIG.
6 has a tip edge portion 26a parallel to the doctor blade 9 (FIG. 1), and the amount of protrusion is the same everywhere in the portions a to e.

With such a developer movement restricting member configuration, the amount of developer pumped up in the central portion (c portion) tends to be slightly larger than that in the end portions (a and e). Become. Thus, as shown in FIG. 4, the leading edge of the projecting portion 26 is gradually increased in the axial direction of the developing sleeve 6 (FIG. 1) from the central portion c toward both ends a and e. When the portion 26a is formed in a curved shape, the developer density (developer powder pressure) at the center tends to decrease, and the amount of the developer pumped up can be equalized in the axial direction of the developing sleeve 6. As a result, the developer can be guided toward the doctor blade 9 (FIG. 1) and the separator 23 (FIG. 4) in a uniform amount in the axial direction.

FIG. 11 (I) shows the difference in the amount of developer pumped in each part when the front edge 26a is parallel (FIG. 2), and FIG. 11 (II) shows the case where the front edge 26a is curved. FIG. 4 shows the difference in the amount of developer pumped in each part. (I)
In this case, even when the developing device is inclined or in a horizontal state, the amount of developer pumped up at the center is large. On the other hand, as shown in (II), by forming the leading edge portion 26a into a curved configuration, the amount of developer pumped up can be equalized.

Incidentally, the separator gap L ₂ shown in FIG.
The amount of the developer returned to the developer increases, and the mixing property of the developer can be improved. FIG. 8 is a diagram illustrating this fact. Therefore, in order to enhance the mixing property of the developer, the separator gap L ₂
However, if it is too large, the powder pressure of the developer sent between the developer movement restricting member 24 and the developing sleeve 6 decreases, and the developer pressure is obtained by the developer movement restricting member 24. The aforementioned effects are reduced. Therefore, reducing the separator gap L ₂ in order to increase this effect, turn return amount of the developer to the separator 23 is decreased.

From such a viewpoint, in the embodiment shown in FIG. 6, the vertical plate portion 25 is not at a right angle but with an obtuse angle (θ) with respect to the projecting direction of the projecting portion 26 in the developer movement regulating member 24. Is formed. When the developer movement restricting member 24 is configured as described above, the amount of developer taken in between the developing sleeve 6 (FIG. 1) and the vertical plate portion 25 can be increased, and the amount of developer returned to the separator 23 can be increased. The mixing property of the developer can be improved. Moreover, since the angle θ forms an obtuse angle, the gap between the developer movement restricting member 24 and the developing sleeve 6 is
Therefore, the powder pressure of the developer between the regulating member 24 and the developing sleeve 6 can be prevented from lowering, and the above-described effect of the developer movement regulating member 24 can be reliably obtained. . That is, it is possible to increase the amount of the developer returned to the separator 23, improve the accumulation of the developer and the agitation property, and prevent a problem caused by the inclination of the developing device.

In FIG. 3, the portion A indicates the lower end of the vertical plate portion 25. If a chamfered portion 25a is provided in this portion as shown in FIG. 7, the developer is removed for the same reason as described above. The amount of developer taken in, the amount of developer returned to the separator 23 is increased, and the developer movement restricting member 2
4 can be prevented from reducing the effect. That is, the vertical plate portion 25 and the developing sleeve 6 are formed by forming the chamfered portion 25a.
By widening the gap between FIG. 1 and FIG. 1, the amount of developer taken in can be increased, the amount of developer returned to the separator 23 can be increased, and the mixing property of the developer can be improved.
Moreover, since the gap is enlarged only at the lower portion of the vertical plate portion 25, it is possible to prevent the powder pressure of the developer between the developer movement restricting member 24 and the developing sleeve 6 from decreasing, and the restricting member 2
The advantage of 4 can be fully utilized.

In manufacturing the separator, in the case of this example, when the dies 29 and 30 as shown in FIG. 12 are used, each of the dies is pulled out in the up and down direction to become a prototype of the separator. The member 28 can be easily manufactured. On the other hand, in the conventional device (FIG. 15), as shown in FIG.
When molding the member 36 serving as a prototype of the separator, three molds 31, 32, and 33 are required for convenience, and two of these molds must be removed in the left-right direction and the oblique direction.

In any case, in the case of this example, the workability is excellent, and further cost reduction can be expected. In addition, as shown in FIG.
If the member 37 serving as a prototype of the separator of the conventional developing device is formed by using 35, in this case, it is only necessary to pull out each mold in the vertical direction. However,
Since the chain line portion 37A becomes thick, the member 37 is likely to be warped, which is not very advantageous.

Although various embodiments according to the present invention have been described above, it is particularly advantageous to appropriately combine the above embodiments.

[0047]

According to the first aspect of the present invention, the developer can be fed into the developer layer thickness regulating member with a high density, so that the developer is controlled by the developer layer thickness regulating member. Can be sufficiently regulated, and the image density can be prevented from lowering. Also, the developer can be sent to the developer layer thickness regulating member while stirring,
Since the rising of the charge of the developer can be made good, it is possible to suppress the occurrence of background stain on the image and to promote the further improvement of the image quality. Further, even if the developing device is inclined, the amount of the developer pumped to the developer layer thickness regulating member can be stabilized, and the image quality can be similarly improved.

According to the second aspect of the present invention, the developer movement restricting member can be simply constructed, which is advantageous in cost.

According to the third aspect of the invention, the effect of the developer movement restricting member can be surely prevented without preventing the mixing property of the developer from lowering and without increasing the rotational load torque of the developing device. Obtainable.

According to the configuration of the fourth aspect, the developer can be uniformly fed to the developer layer thickness regulating member in the axial direction of the developer carrying member.

According to the fifth aspect, the developer is sufficiently taken in between the developer carrying / transporting member and the developer movement restricting member to prevent the mixing property of the developer from being lowered. In addition, it is possible to enhance the ability of the developer to accumulate and agitate in the meantime.

According to the structure of the sixth aspect, the developer movement restricting member and the separator are one component, so that
The number of parts is reduced, which is advantageous in terms of cost.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing only a main part of a developing device according to an embodiment of the present invention.

FIG. 2 is a perspective view of a separator provided in the developing device.

FIG. 3 is a diagram for explaining the magnitude relationship of the protruding length of a protruding portion of a developer movement regulating member.

FIG. 4 is a perspective view of another example of a separator.

FIG. 5 is a diagram illustrating a correlation characteristic between a protrusion length of a protrusion and a rotational load torque of a developing device.

FIG. 6 is a configuration diagram of another example of a developer movement restricting member.

FIG. 7 is a partial view of the vertical plate portion of the example in which a chamfered portion is provided on the vertical plate portion of the developer movement restricting member.

FIG. 8 is a diagram showing a correlation characteristic between a separator gap and a mixing property of a developer.

FIG. 9 shows an example of the present invention and a conventional example.
FIG. 6 is a diagram illustrating a correlation characteristic between a toner supply amount and a background stain generation rank.

FIG. 10 is a diagram showing a correlation characteristic between the amount of inclination of the developing device and the amount of developer pumped in the case of the present invention and the case of the conventional example.

FIG. 11 shows a case where the tip edge of the protruding portion is made parallel,
FIG. 7 is a diagram illustrating how the amount of developer pumped changes with respect to the position of each part of the developing device when the developing device is curved.

FIG. 12 is a diagram illustrating a method of extracting a mold when a member serving as a prototype of the separator of the present example is molded.

FIG. 13 is a diagram illustrating a method of extracting a mold when a member serving as a prototype of a conventional separator is molded.

FIG. 14 is a diagram illustrating a method of extracting a mold when a member serving as a prototype of a conventional separator is molded.

FIG. 15 is a diagram illustrating an example of a developing device having a separator having a conventional configuration.

FIG. 16 is a plan view of a conventional separator.

FIG. 17 is a diagram illustrating an example of a developing device having a separator positioned below a doctor blade.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 3 Developing container 4 Developing agent 6 Developer carrying member 11 Developing device 23 Separator 24 Developing agent movement regulating member 25 Vertical plate portion 26 Projection portion

Continuation of the front page (56) References JP-A-63-113479 (JP, A) JP-A-61-112175 (JP, A) JP-A-2-25876 (JP, A) JP-A-63-4278 (JP) , A) (58) Field surveyed (Int. Cl. ⁷ , DB name) G03G 13/08-13/095 G03G 15/08-15/095

Claims (4)

(57) [Claims] And 1. A developer container containing a developer, a layer of the developer in the circumferential surface carrying the current image agent you conveyed carried and conveyed to the member, the developer supplied to the developer carrying conveying member on ; and a developer layer thickness regulating member for regulating before developing the thickness, the developing device of the image forming apparatus, for moving a pre Kigen image agent with stirring reservoir before heading to the developer layer thickness regulating member The developer movement regulating member is provided so as to face the developer carrying conveyance member, and the developer movement regulating member is provided with the developer carrying member.
The space between the transfer member and the transfer member widens in the developer movement direction.
So as to be opposed to the developer carrying member.
And a lower portion of the vertical plate in the developer moving direction.
A protrusion protruding from the flow side end toward the developer carrying member
And the projecting portion, wherein the projecting portion is the vertical plate portion.
以下 or less of the distance between the developer carrying member
A developing device characterized in that the developing device protrudes from the developing device. 2. The protruding portion includes a shaft of a developer carrying and conveying member .
In the direction, as you go from the center to both ends,
Projection amount gradually developing device according to claim 1 that is larger. 3. The direction in which the vertical plate portion projects from the projecting portion.
The developing device according to claim 1 or 2 that have an obtuse angle with respect to. 4. The developer movement restricting member includes a developer layer thickness restricting member.
The developer removed by the member is returned to the side of the developing container.
In order of the separator, according to claim 1 to 3 that is integrally formed
The developing device according to any one of the above.