JP3575249B2 - Developing device - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a developing device that records and forms a toner image on a photoconductor using a well-known electrophotographic process, such as a laser printer or a copying machine.
[0002]
[Prior art]
4, 5 and 6 show the prior art. FIG. 4 is a side sectional view of the developing device, FIG. 5 is a perspective view of a developer deflector, and FIG. 6 is an explanatory diagram showing a regulated state of the developer layer.
In the figure, a magnetic roller 2 for transporting a developer and magnetic rollers 4 and 5 for developing are rotatably supported in the casing 1 of the developing device so as to be rotatable in directions indicated by arrows. Each of the magnetic rollers 2, 4, and 5 is, for example, a developing device of this type that includes a magnet roller having a plurality of magnetic poles on a circumference and a sleeve that includes the magnet roller and is rotatably provided. Well-known rollers are used. Between the magnetic roller 4 and the magnetic roller 5, there is provided a doctor plate 6 for regulating the amount of developer supplied when supplying the developer drawn up by the magnetic roller 2 to the magnetic rollers 4 and 5.
[0003]
A developer deflector 8 is provided downstream of the magnetic roller 5 with respect to the development area DA5 in the developer transport direction. As shown in FIG. 5, the developer deflector 8 is provided with a separating plate 8c, a plurality of deflecting plates 8a provided on one side of the separating plate 8c, and provided on the other side of the separating plate 8c. And a plurality of deflection plates 8b inclined in the opposite direction. Further, a developer deflector 7 is provided downstream of the magnetic roller 4 with respect to the development area DA4 in the developer transport direction. The developer deflector 7 has the same configuration as the developer deflector 8 described above.
[0004]
Below the developer deflector 8, there are provided a guide plate 9 for guiding the developer 15b to the toner replenishing point TSP, and a regulating plate 10 supported at a fixed distance d from the upper surface of the guide plate 9. Here, since the developer 15b is divided and collected by the respective deflecting plates 8a and 8b, when the developer 15b drops from the developer deflector 8, each pitch and deflection of the deflecting plate 8a as shown in FIGS. A thick portion α of the developer layer and a thin portion β of the developer layer appear alternately corresponding to each pitch of the plate 8b, resulting in a streak-like flow in which the thickness of the developer layer is uneven in the axial direction. When the toner 16 is replenished from the toner hopper 13 in a state where the thickness of the developer layer is not uniform, the replenished toner 16 is changed from a thick part α to a thin part β of the developer layer, that is, from a high part to a low part. Therefore, the toner density of the thick portion α is low, and the toner density of the thin portion β is high, and when printing is performed, a streak-like print density unevenness appears. In addition, since the toner density becomes non-uniform, the toner density sensor 12 cannot accurately detect the toner density, and excessive or small toner replenishment is performed, and the print density becomes too high as a whole, or conversely. Problems such as excessive thinning occur. The regulation plate 10 is provided for the purpose of solving such a problem.
[0005]
In the figure, reference numeral 11 denotes a stirring paddle provided adjacent to the magnetic roller 2, 12 denotes a toner density sensor, 13 denotes a toner hopper provided adjacent to the casing 1, and 14 denotes a toner hopper. A toner supply roller that feeds the toner 16 into the casing 1 as needed.
[0006]
In the above-described configuration, the two-component powder developer 15 including the toner and the carrier housed in the casing 1 is conveyed by the rotation of the magnetic roller 2 and delivered to the magnetic rollers 4 and 5. The developer 15 transferred to the magnetic rollers 4 and 5 is regulated to a predetermined thickness by the doctor plate 6, conveyed to the developing areas DA 4 and DA 5 of the magnetic rollers 4 and 5, and formed on the photoconductor 3. The toner 16 in the developer 15 is supplied to the electrostatic latent image to form a toner image on the photoconductor 3.
[0007]
After passing through the developing area DA5, the developer 15b on the magnetic roller 5 is separated from the magnetic roller 5 and falls to the developer deflector 8, and is deflected by a plurality of deflecting plates 8a and 8b in the longitudinal direction (axial direction) of the magnetic roller 5. ). The developer 15 b descends in the developer deflector 8, so that the frictionally charged state that has become unstable due to the consumption of toner in the previous developing process is made uniform. The developer 15 b discharged from the developer deflector 8 slides down on a guide plate 9 provided below the developer deflector 8, and the thickness of the developer layer is regulated by the regulating plate 10. And returns to the bottom of the casing 1 again. The developer 15 b returned to the bottom of the casing 1 is further transported by the stirring paddle 11, the toner density is measured by the toner density sensor 12, and returned to the magnetic roller 2 side.
[0008]
Further, when the toner in the developer 15 is consumed, the toner concentration decreases, and when the toner concentration measured by the toner concentration sensor 12 falls below a certain level, the toner replenishing roller 14 is driven and the toner 16 in the toner hopper 13 is removed. The developer 15 is supplied. Further, the developer 15a used by the magnetic roller 4 falls to the developer deflector 7, and is conveyed and agitated similarly to the case of the developer 15b. They merge and are sent to the magnetic roller 2 again.
[0009]
[Problems to be solved by the invention]
By the way, in the configuration of the related art, since the tip (lower end) of the regulating plate 10 is straight, it is difficult to set the distance d between the upper surface of the guide plate 9 and the tip of the regulating plate 10, and the developer to the regulating portion is difficult. Can be balanced only when the interval between the inflow amount of the developer and the regulated amount of the developer flowing out coincides with each other. If the interval d is at least slightly wide, the developer 15b slips through as it is uneven, resulting in a streak-like print density. Unevenness cannot be eliminated. Further, if the distance d is small, the developer overflows from above the developer deflector 8 and the rotation of the magnetic roller 5 is locked, which adversely affects the transportability of the developer.
[0010]
SUMMARY OF THE INVENTION An object of the present invention is to provide a developing device capable of uniformly adjusting unevenness of a developer layer caused when the developer layer is lowered through a deflecting plate having a different inclination direction, and which is less likely to cause print density unevenness. .
[0011]
[Means for Solving the Problems]
The above object is achieved by providing the powder developer (15b) detached from the developer carrier (5) with a deflecting plate (8a) inclined to one end in the longitudinal direction of the developer carrier, and the other end of the developer carrier in the longitudinal direction. A developer deflecting means (8) for lowering while being guided by a deflecting plate (8b) inclined to the end side; a guide member (9) for guiding the developer passing through the developer deflecting means in a predetermined direction; A regulating member (17) supported at a predetermined interval with respect to the developer guide surface of the guide member and configured to make the layer thickness of the developer moving on the developer guide surface uniform. Of the developer discharged on the developer guide surface, a convex portion (17a) in contact with the thick portion (α) of the developer layer and a concave portion (17b) facing the thin portion (β) of the developer layer. This is achieved by having
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a side sectional view of a developing device of the present invention, FIG. 2 is a perspective view of a developer deflector of the present invention, and FIG. 3 is an explanatory diagram showing a state in which the layer thickness of the developer is regulated.
[0013]
In the figure, a magnetic roller 2 for transporting a developer and magnetic rollers 4 and 5 for developing are rotatably supported in the casing 1 of the developing device so as to be rotatable in directions indicated by arrows. Each of the magnetic rollers 2, 4, and 5 is, for example, a developing device of this type that includes a magnet roller having a plurality of magnetic poles on a circumference and a sleeve that includes the magnet roller and is rotatably provided. Well-known rollers are used. Between the magnetic roller 4 and the magnetic roller 5, there is provided a doctor plate 6 for regulating the amount of developer supplied when supplying the developer drawn up by the magnetic roller 2 to the magnetic rollers 4 and 5.
[0014]
A developer deflector 8 is provided downstream of the magnetic roller 5 with respect to the development area DA5 in the developer transport direction. As shown in FIG. 2, the developer deflector 8 is provided with a separating plate 8c, a plurality of deflecting plates 8a provided on one side of the separating plate 8c, and provided on the other side of the separating plate 8c. And a plurality of deflection plates 8b inclined in the opposite direction. Further, a developer deflector 7 is provided downstream of the magnetic roller 4 with respect to the development area DA4 in the developer transport direction. The developer deflector 7 has the same configuration as the developer deflector 8 described above.
[0015]
Below the developer deflector 8, there are provided a guide plate 9 for guiding the developer 15b to the toner supply point TSP, and a regulating plate 17 supported above the guide plate 9. In the figure, reference numeral 11 denotes a stirring paddle provided adjacent to the magnetic roller 2, 12 denotes a toner density sensor, 13 denotes a toner hopper provided adjacent to the casing 1, and 14 denotes a toner hopper. A toner supply roller that feeds the toner 16 into the casing 1 as needed.
[0016]
In the above-described configuration, the two-component powder developer 15 including the toner and the carrier housed in the casing 1 is conveyed by the rotation of the magnetic roller 2 and delivered to the magnetic rollers 4 and 5. The developer 15 transferred to the magnetic rollers 4 and 5 is regulated to a predetermined thickness by the doctor plate 6, conveyed to the developing areas DA 4 and DA 5 of the magnetic rollers 4 and 5, and formed on the photoconductor 3. The toner 16 in the developer 15 is supplied to the electrostatic latent image to form a toner image on the photoconductor 3.
[0017]
After passing through the developing area DA5, the developer 15b on the magnetic roller 5 is separated from the magnetic roller 5 and falls to the developer deflector 8, and is deflected by a plurality of deflecting plates 8a and 8b in the longitudinal direction (axial direction) of the magnetic roller 5. ). The developer 15 b descends in the developer deflector 8, so that the frictionally charged state that has become unstable due to the consumption of toner in the previous developing process is made uniform. The developer 15 b discharged from the developer deflector 8 slides down on a guide plate 9 provided below the developer deflector 8, and the thickness of the developer layer is regulated by a regulating plate 17. And returns to the bottom of the casing 1 again. The developer 15 b returned to the bottom of the casing 1 is further transported by the stirring paddle 11, the toner density is measured by the toner density sensor 12, and returned to the magnetic roller 2 side.
[0018]
Further, when the toner in the developer 15 is consumed, the toner concentration decreases, and when the toner concentration measured by the toner concentration sensor 12 falls below a certain level, the toner replenishing roller 14 is driven and the toner 16 in the toner hopper 13 is removed. The developer 15 is supplied. Further, the developer 15a used by the magnetic roller 4 falls to the developer deflector 7, and is conveyed and agitated similarly to the case of the developer 15b. They merge and are sent to the magnetic roller 2 again.
[0019]
In the present invention, the regulating plate 17 includes, among the developer 15b discharged on the upper surface of the guide plate 9, a convex portion 17a in contact with a portion α where the developer layer is thick, and a concave portion 17b in opposition to a portion β where the developer layer is thin. And the convex portion 17a is formed in an arc shape.
[0020]
With the above-described configuration, when the developer 15b having the streak-like unevenness as it descends from the developer deflector 8 passes through the regulating plate 17, only the portion α where the developer layer is thicker is formed on the convex portion 17a of the regulating plate 17. The contact thickness is restricted. At this time, since the tip of the convex portion 17a has an arc shape, the developer 15b of the α portion regulated around the vertex portion is smoothly divided into left and right, flows into β1 and β2, and flows into β1 and β2 to form the developer layer. The concave portion is filled. For this reason, the developer layer is prepared almost uniformly, and it is possible to prevent streak-like print density unevenness which is a problem in print quality.
[0021]
In addition, even if the distance between the guide plate 9 and the control plate 17 is widened due to variations in the distance between the control portions, the lap amount between the convex portion 17a of the control plate 17 and the portion α where the developer layer is thick is sufficient. Therefore, although the amount of the developer in contact with the regulating plate 17 is reduced, the thick portion α of the developer layer can be prevented from slipping through as it is, the unevenness of the developer layer is reduced, and the streak-like print density unevenness is inconspicuous. It becomes possible to level the developer layer.
[0022]
Further, when the distance between the guide plate 9 and the regulating plate 17 is small and the amount of the developer contacting the regulating plate 17 is large, the amount of the developer flowing into β1 and β2 becomes large. Portion tends to be lower than the β portion, but the developer layer is smoothed to such an extent that streak-like print density unevenness is not conspicuous without causing overflow of the developer from above the developer deflector 8. Becomes possible.
[0023]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to this invention, the unevenness | corrugation of the developer layer which arises when it falls through the deflecting plate from which an inclination direction differs can be adjusted uniformly, and the developing device which is hard to generate | occur | produce a printing density unevenness can be provided. .
[Brief description of the drawings]
FIG. 1 is a side sectional view of a developing device of the present invention.
FIG. 2 is a perspective view of a developer deflector of the present invention.
FIG. 3 is an explanatory view showing a state in which a layer thickness of a developer is regulated.
FIG. 4 is a side sectional view of a conventional developing device.
FIG. 5 is a perspective view of a conventional developer deflector.
FIG. 6 is an explanatory view showing a state in which a layer thickness of a developer is regulated in a conventional technique.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Casing, 2, 4, 5 ... Magnetic roller, 3 ... Photoconductor, 6 ... Doctor plate, 7, 8 ... Developer deflector, 9 ... Guide plate, 11 ... Stirring paddle, 12 ... Toner density sensor, 13 ... Toner container, 14: toner supply roller, 15: developer, 16: toner, 17: regulating plate.

Claims (2)

The powder developer separated from the developer carrier is lowered while being guided by a deflecting plate inclined to one longitudinal end of the developer carrier and a deflecting plate inclined to the other longitudinal end of the developer carrier. Developer deflecting means for causing
A guide member for guiding the developer passing through the developer deflecting unit in a predetermined direction;
A regulating member that is supported at a predetermined interval with respect to the developer guide surface of the guide member and that makes the layer thickness of the developer moving on the developer guide surface uniform.
The regulating member has a convex portion that comes into contact with a thick portion of the developer layer and a concave portion that faces a thin portion of the developer layer, of the developer discharged on the developer guide surface. Developing device. 2. The developing device according to claim 1, wherein a tip of the convex portion of the regulating member is formed in an arc shape.

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