JP5028981B2 - Developing device and image forming apparatus using the same - Google Patents

Description

The present invention relates to a developing device and an image forming apparatus using the developing device .

2. Description of the Related Art Conventionally, as a developing device, a device including a developing container that contains a developer and a developing roll that is provided in the developing container and transports the developer to a developing area is widely used.
In this type of developing device, as the developing roll, a developing roller provided with a rotatable developing sleeve and a magnet member provided with a predetermined number of magnetic poles arranged in the developing sleeve is used. In order to keep the developer transportability on the roll well, those that have been devised in various ways have already been proposed (for example, Patent Documents 1 to 5).

Patent Document 1 describes a two-component development type developing device using a developer containing toner and carrier, in order to realize a uniform development characteristic in the axial direction of the developing roll, between a developing sleeve and a layer thickness regulating member. The gap is made different between the central portion and the end portion in the axial direction, thereby correcting variations in development characteristics at the axial end portion of the developing roll.
Patent Document 2 discloses a two-component developing system developing device in which a portion having a larger magnetic force has a change so as to reduce the surface roughness in accordance with the magnetic force generated by the magnet body in the axial direction of the developing sleeve. This is to correct the magnetic force due to increase at the end of the developing roll.
In Patent Document 3, in a developing device of a two-component development system, the surface shape of the end portion of the developing sleeve has a shape in which the developer conveying force is larger than that of the central portion, and development accompanying a decrease in magnetic force at the end portion of the developing roll. It corrects the decrease in the agent.

In Patent Document 4, in a developing device of a one-component developing system using a developer containing toner, the toner conveyance amount at the longitudinal end portion of the outer surface of the sleeve in the magnet roll (magnet member) is made smaller than that in the central portion. The toner prevents the toner from overflowing from the end of the sleeve.
Japanese Patent Application Laid-Open No. 2005-228688 deals with a one-component developing type developing apparatus in which the surface roughness of the developing sleeve surface is reduced continuously or stepwise from both ends of the developing region toward the center. This increases the surface roughness of the developing sleeve corresponding to both ends of the image area where the toner consumption is small, improving the toner conveying effect when passing through the gap between the blade and the sleeve surface, and the toner charge amount can be reduced without causing toner aggregation. It suppresses excessive rise. As a result, even at the both ends of the image area, it is intended to prevent background fogging by avoiding thickening of the toner thin layer due to the high suction force between the sleeve and the toner.

Japanese Patent Laying-Open No. 2003-140461 (Embodiment of the Invention, FIG. 1) Japanese Patent Laid-Open No. 5-341656 (Example, FIG. 3) JP-A-8-162321 (Example, FIG. 2) Japanese Unexamined Patent Publication No. 2003-186307 (Embodiment of the Invention, FIG. 5) Japanese Patent Laying-Open No. 2003-156931 (Embodiment of the Invention, FIG. 6)

The present invention pays attention to the surface property of the developing sleeve used in the two-component developing device, and continuously along the axial direction of the developing sleeve due to the difference in the developer conveying ability between the developing sleeve and the layer thickness regulating member. It is a technical problem to be solved to easily correct the nonuniformity of the changing image density distribution.

Invention, the toner and developer container developer can accommodate comprising a carrier, and and the developer can be held conveyance developing roll provided in the developing container, non the upper side of the developing roll according to claim 1 A developing device comprising: a developing device comprising: a developing member that holds and conveys the developer; and a developing device comprising: A magnetic member fixedly provided in the developing sleeve and having a plurality of magnetic poles arranged thereon. The developing sleeve further comprises a sleeve main body formed of a nonmagnetic material, and a surface of the sleeve main body is rough. A surface rough surface portion that is changed to have a rough surface state in a tendency to reduce a difference in developer conveying ability that is surfaceized and continuously changes along the axial direction of the sleeve body, The layer thickness Three or more levels of developer conveyance capability from the center to the end in the axial direction of the sleeve body so as to reduce the difference in developer conveyance capability corresponding to the amount of deflection that varies along the axial direction of the sleeve body facing the control member. The developing device is characterized in that it is divided into the above areas and enlarged in a stepwise manner.
According to a second aspect of the present invention, in the developing device according to the first aspect, the surface rough surface portion has a surface roughness that increases from the central portion of the sleeve body in the axial direction to the end portion. is there.
According to a third aspect of the present invention, in the developing device according to the first aspect, the rough surface portion has a groove portion that extends along the axial direction of the sleeve body and can hold and convey the developer, and the depth of the groove portion. Is a developing device characterized in that the depth becomes deeper from the central portion of the sleeve body in the axial direction to the end portion.

According to a fourth aspect of the present invention, in the developing device according to the first aspect, the rough surface portion has a groove portion that extends along the axial direction of the sleeve body and can hold and convey the developer, and the width of the groove portion is the sleeve width. The developing device is widened from the central portion to the end in the axial direction of the main body.
According to a fifth aspect of the present invention, in the developing device according to the first aspect, the irregular surface having regularity in which the rough surface portion includes a convex block having a regular shape and a concave groove formed between the convex blocks. The developing device is characterized by comprising a pattern, and the uneven pattern increases the ratio of the groove from the central portion of the sleeve body in the axial direction to the end portion .

According to a sixth aspect of the present invention, in the developing device according to the first aspect , the rough surface portion corresponds to a deflection amount that varies along the sleeve body and a deflection amount that varies along the longitudinal direction of the layer thickness regulating member. The developing device is characterized in that the developer conveying capability is increased from the central portion of the sleeve main body in the axial direction to the end so as to reduce the difference in developer conveying capability .

According to a seventh aspect of the present invention, there is provided an image holding member capable of holding an image, and a developer containing toner and a carrier, the electrostatic latent image provided opposite to the image holding member and formed on the image holding member. An image forming apparatus comprising: a developing device that visualizes the image of the developing device, wherein the developing device is capable of storing a developer; the developer container is provided in the developer container; and the developer can be held and conveyed A developing roll, and a layer thickness regulating member that is opposed to the upper side of the developing roll in a non-contact state and regulates the layer thickness of the developer on the developing roll, and the developing roll holds the developer. A developing sleeve to be conveyed; and a magnet member fixedly provided in the developing sleeve and arranged with a plurality of magnetic poles, and the developing sleeve further comprises a sleeve body formed of a nonmagnetic material; The surface of the sleeve body is roughened. A surface rough surface portion that can change the rough surface state in a tendency to reduce the difference in developer conveying ability that continuously changes along the axial direction of the sleeve body, and the surface rough surface portion has the layer thickness. Three or more developer conveying capacities from the center to the end in the axial direction of the sleeve main body so as to reduce the difference in developer conveying capability corresponding to the amount of deflection changing along the axial direction of the sleeve main body facing the regulating member. The image forming apparatus is characterized in that the image forming apparatus is divided into a plurality of areas and enlarged in stages.

According to the invention which concerns on Claim 1, there exist the following technical effects.
(1) Compared to the case where this configuration is not provided, the difference in developer conveying ability in the axial direction of the developing sleeve caused by the difference in developer conveying ability between the developing sleeve and the layer thickness regulating member is reduced, and this Thus, it is possible to provide a developing device that can easily correct non-uniformity of the image density distribution that continuously changes along the axial direction of the developing sleeve.
(2) Developer conveyance in the axial direction of the developing sleeve is adjusted by adjusting the difference in developer conveying ability corresponding to the amount of deflection that varies along the axial direction of the developing sleeve as compared to the case without this configuration. Capability difference can be easily reduced.
(3) The developing sleeve can be easily manufactured by changing the surface rough surface portion of the developing sleeve in a stepwise manner as compared with the continuously changing mode.
According to the second aspect of the present invention, the developer conveying ability difference in the axial direction of the developing sleeve is adjusted by adjusting the surface roughness distribution of the surface rough surface portion of the developing sleeve as compared with the case without this configuration. Can be easily reduced.
According to the third aspect of the present invention, the developer conveying ability in the axial direction of the developing sleeve is adjusted by adjusting the depth of the groove portion as the surface rough surface portion of the developing sleeve as compared with the case where this configuration is not provided. The difference can be easily reduced.
According to the fourth aspect of the invention, compared to the case without this configuration, by adjusting the groove width as the surface rough surface portion of the developing sleeve, the difference in developer conveying ability in the axial direction of the developing sleeve is reduced. It can be easily reduced.
According to the fifth aspect of the invention, compared to the case without this configuration, by adjusting the uneven pattern distribution as the surface rough surface portion of the developing sleeve, the developer conveying ability difference in the axial direction of the developing sleeve. Can be easily reduced.

According to the sixth aspect of the present invention, compared to the case where the present configuration is not provided, the difference in developer conveying ability corresponding to the amount of deflection along the axial direction of the developing sleeve and the layer thickness regulating member is reduced, thereby It is possible to provide a developing device that can easily correct non-uniformity of the image density distribution that continuously changes along the axial direction of the developing sleeve.
According to the seventh aspect of the present invention, as compared with the case where the present configuration is not provided, it is continuous along the axial direction of the developing sleeve due to the difference in the developer conveying ability between the developing sleeve and the layer thickness regulating member. Therefore, it is possible to easily construct an image forming apparatus capable of easily correcting the non-uniformity of the image density distribution that changes to the above.

First, an outline of an embodiment model to which the present invention is applied will be described.
Outline of Embodiment Model FIG. 1A shows an outline of an image forming apparatus according to an embodiment model embodying the present invention.
In FIG. 1, an image forming apparatus includes an image carrier 11 such as a photosensitive drum, and an electrostatic latent image formed on the image carrier 11 that faces the image carrier 11 and includes toner and a carrier. And a developing device 12 that visualizes the image with the developer G.
Here, one of the representative models of the developing device 12 includes a developing container 6 that can store the developer G, a developing roll 7 that is provided in the developing container 6 and that can hold and convey the developer G, and And a layer thickness regulating member 8 that is disposed to face the developing roll 7 and regulates the layer thickness of the developer G on the developing roll 7, and the developing roll 7 includes a developing sleeve 1 that holds and conveys the developer G; A magnet member 5 is provided which is fixedly provided in the developing sleeve 1 and in which a plurality of magnetic poles are arranged.
In particular, in the present embodiment, the developing sleeve 1 includes a sleeve main body 2 formed of a nonmagnetic material, and a surface of the sleeve main body 2 is roughened and continuously along the axial direction of the sleeve main body 2. And a surface rough surface portion 3 in which the rough surface state is changed so as to reduce the difference in developer conveying ability that changes.

In such technical means, the rough surface portion 3 may be any structure that roughens the surface of the sleeve body 2, and the manufacturing method thereof may be appropriately selected, such as a sandblasting method, a drawing method, or an etching method.
Further, the rough surface state of the surface rough surface portion 3 only needs to change continuously or stepwise along the axial direction of the sleeve body 2, but continuously changes along the axial direction of the sleeve body 2. What is necessary is just to set so that a developer conveyance capability difference may be made small.
Here, the “developer conveyance capacity difference that continuously changes along the axial direction of the sleeve main body 2” refers to the amount of bending that changes along the axial direction of the sleeve main body 2 and the axial direction of the layer thickness regulating member 8. In addition to the factors caused by the amount of deflection that changes along the line, it is intended to include a wide range of factors caused by factors unique to the image forming apparatus. In the present embodiment model, the surface rough surface portion 3 is one of these or a combination of factors. Any developer can be used as long as it can be changed to a tendency to reduce the difference in developer conveyance capability caused by the above.
In addition, when the difference in developer conveyance capability described above is large, the developer conveyance capability varies in the axial direction. The variation in the axial direction of the developer conveyance capability is “continuously along the axial direction of the developing sleeve 1. This leads to “nonuniformity of the changing image density distribution”.
That is, the factors of “nonuniformity of the image density distribution continuously changing along the axial direction of the developing sleeve 1” include a. A variation in the axial direction of the developer conveying ability that continuously changes depending on the amount of deflection that changes along the axial direction of the developing sleeve 1 (developing roll 7) and the layer thickness regulating member 8 used in the two-component developing device, b. Based on variations in the axial direction of the image carrier 11 of the latent image potential distribution caused by characteristics unique to the image forming apparatus (for example, exposure optical characteristics), there are variations in the axial direction of the developer transport capability that occur in the development area of the developing device. .
More specifically, in the present embodiment model, as shown in FIG. 1B, for example, the developing sleeve 1 (developing roll 7) is bent along the axial direction. 1 and the layer thickness regulating member 8 become non-uniform. Specifically, the gap g _c of the central portion of the developing sleeve 1 is made wider than the gap g _e in the developing region ends of the developing sleeve 1. At this time, the surface rough surface portion 3 of the developing sleeve 1 extends from the central portion in the axial direction to the end portion of the developing sleeve 1 so as to reduce the developer conveying ability that continuously changes with the amount of deflection of the developing sleeve 1. What is necessary is just to set so that the developer conveyance capability W may be increased. In this way, the developer conveying ability W due to the surface property of the developing sleeve 1 is continuously reduced with the amount of deflection of the developing sleeve 1 so that the difference in developer conveying ability is reduced. The developer transport amount M in each part is adjusted to be substantially constant.

Hereinafter, the present invention will be described in more detail based on embodiments shown in the accompanying drawings.
Embodiment 1
FIG. 2 shows Embodiment 1 of an image forming apparatus to which the present invention is applied.
In the figure, the image forming apparatus has a photosensitive drum 20 capable of holding an electrostatic latent image, and around the photosensitive drum 20, a charging device 21 for precharging the photosensitive drum 20; A latent image writing device 22 such as a laser scanning device in which an electrostatic latent image is written on the charged photosensitive drum 20, and the electrostatic latent image written on the photosensitive drum 20 are visualized with a developer. The developing device 30, the transfer device 23 that electrostatically transfers the visualized image on the photosensitive drum 20 to the recording material 25, and the developer remaining on the photosensitive drum 20 is cleaned. The cleaning devices 24 are sequentially arranged.

In the present embodiment, as shown in FIG. 3, the developing device 30 includes a developing container 31 that contains a two-component developer G containing toner and a carrier and opens toward the photosensitive drum 20. A developing roll 32 capable of holding and transporting the developer is disposed at a position facing the opening 31 a of the developing container 31, and a layer thickness regulating member that regulates the developer layer on the developing roll 32 in the vicinity of the developing roll 32. 33 is provided. In addition, although the thing of a plate-shaped member is shown as the layer thickness control member 33, it is not restricted to this, For example, a roll-shaped member may be sufficient.
Further, the developing device 30 is circulated and transported in which a developing wall 32 of the developing container 31 is partitioned by a partition wall 36 on the back side and through holes (not shown) are opened at both longitudinal ends of the partition wall 36. A path 37 is provided, and agitating and conveying members 34 and 35 for stirring and conveying the developer are disposed in the respective linear paths of the circulation and conveying path 37, and further, between the developing roll 32 and the agitating and conveying member 34. For example, a paddle-shaped supply member 38 for supplying the developer to the developing roll 32 is provided as necessary.

In the present embodiment, the developing roll 32 includes a developing sleeve 41 made of a rotatable nonmagnetic member (such as aluminum or stainless steel) and a magnet roll 42 provided in the developing sleeve 41.
Here, a plurality of magnetic poles (for example, 5 magnetic poles) (not shown) are arranged on the magnet roll 42. For example, sites which the layer thickness regulating member 33 and substantially opposite is arranged a layer thickness regulating pole for the layer thickness regulating (e.g. N ₁ pole), forming a development zone n of the predetermined range in a portion facing the photosensitive drum 20 developing magnetic pole (e.g., S ₁ pole) is arranged to, conveying pole (eg, N ₂ pole) on the downstream side of the developing magnetic pole, peeling pole (e.g. S ₂ poles for the developer peeling at a downstream side of the conveyance pole ) and the pickup pole of the developer pickup (e.g. S ₃ pole) is disposed.

In particular, in the present embodiment, the developing sleeve 41 incorporates a magnet roll 42 therein, and is a member that is long in the axial direction and supported at both ends. Therefore, as shown in FIGS. The developing sleeve 41 has (1) deformation due to its own weight, (2) deformation caused when the developer G is attracted to the magnet roll 42, and (3) developer G is formed between the developing sleeve 41 and the layer thickness regulating member 33. Due to factors such as the pressing force generated when slipping through the gap, the center portion in the axial direction is bent and deformed. In this case, wider than the gap g _e between the gap g _c is the developing region ends and the layer thickness regulating member 33 of the developing sleeve 41 between the axially central portion and the thickness regulating member 33 of the developing sleeve 41 Thus, the gap between them becomes non-uniform along the axial direction of the developing sleeve 41. In this case, as shown in FIG. 4C, the developer G held and transported to the developing sleeve 41 is regulated in layer thickness at the layer thickness regulating member 33, but between the developing sleeve 41 and the layer thickness regulating member 33. Since the gap between them is not uniform, if it is assumed that the surface property of the developing sleeve 41 is uniform, the developer G whose layer thickness is regulated by the layer thickness regulating member 33 is in the axial direction of the developing sleeve 41. On the other hand, the central part tends to be larger than the end part.

However, in the present embodiment, the developing sleeve 41 has a surface rough surface portion 46 formed on the surface of the sleeve main body 45 as shown in FIG. The surface roughened portion 46 is obtained by roughening the sleeve main body 45 by, for example, sand blasting. In the present embodiment, the surface roughened is roughened from the center to the end in the axial direction of the sleeve main body 45. It is a thing.
In the present embodiment, the rough surface portion 46 is located in the middle of the sleeve main body 45 in a plurality of regions, for example, the A region including the central portion, the C region including the end of the sleeve main body 45, and the A region and the C region. When the surface roughness of each of the regions A to C is Rz (A), Rz (B), Rz (C), Rz (A) <Rz (B) <Rz (C) It is set in stages to meet.
Here, in order to change the surface roughness by the sandblast method, the spraying pressure of the abrasive grains may be changed or the spraying time may be changed.
In the present embodiment, the surface rough surface portion 46 divides the sleeve main body 45 into three regions. However, the present invention is not limited to this, and the surface rough surface portion 46 is divided into more divided regions to change the surface roughness. You may make it adjust suitably.

Furthermore, an example of the manufacturing method of the developing roll 32 used in this embodiment is shown in FIG.
As shown in FIG. 6A, the surface rough surface portion 46 is formed on the outer surface of the sleeve body 45 by, for example, sandblasting 110, and the developing sleeve 41 is manufactured.
Thereafter, as shown in FIG. 6B, the magnet roll 42 is inserted into the developing sleeve 41. The magnet roll 42 is fixedly provided with a shaft 421 that passes therethrough.
Thereafter, as shown in FIG. 6C, both ends of the developing sleeve 41 are fixed by flanges 111 and 112, and the shaft 421 of the magnet roll 42 is attached to each flange 111 and 112 by bearings 114 and 115. The developing sleeve 41 is rotated by driving the shaft 113 of the flange 112 with a driving force from a driving source (not shown) while the shaft 421 of the magnet roll 42 is fixed. It is like that.

Next, the operation of the image forming apparatus according to the present embodiment will be described focusing on the developing device.
In FIG. 2, when an electrostatic latent image (not shown) is formed on the photosensitive drum 20, the electrostatic latent image is visualized by the developing device 30.
At this time, in the developing device 30, the developer G on the developing roll 32 is regulated by the layer thickness regulating member 33 and then transported to the developing area n which is a portion facing the photosensitive drum 20 for development. Is done.
Here, the operation of the developing device 30 will be described. The developing roll 32 (developing sleeve 41) bends along the axial direction so that the amount of bending becomes large (away from the layer thickness regulating member 33). As shown in FIG. 7A, the gap (Gap) with the layer thickness regulating member 33 tends to decrease continuously toward both ends with the peak in the axial center.
In the present embodiment, the surface roughness of the developing roll 32 (developing sleeve 41) is the change tendency of the gap (Gap) between the developing roll 32 and the layer thickness regulating member 33, as shown in FIG. Since the reverse tendency is variably set, a large amount of developer passing through the gap is secured at a location where the gap between the developing roll 32 and the layer thickness regulating member 33 is wide, but the surface roughness of the developing roll 32 is small. On the other hand, the amount of the developer transported is suppressed, and in the portion where the gap is narrow, the amount of developer passing through the gap is small, but the amount of developer transported is the amount that the surface roughness of the developing roll 32 is set large. Promoted.
For this reason, since the surface roughness distribution of the developing roll 32 tends to cancel out the gap distribution, the developer conveyance amount at the axial position of the developing roll 32 is substantially constant as shown in FIG. Set to
In the comparative embodiment in which the surface roughness of the developing sleeve 41 is constant, the developer transport amount at the axial position of the developing roll 32 is the same as that of the developing roll 32 and the layer as shown in FIG. A non-uniform tendency similar to the gap distribution with the thickness regulating member 33 is shown.

Embodiment 2
FIG. 8 shows the surface structure of the developing sleeve 41 used in the developing device of the image forming apparatus of the second embodiment.
As shown in FIGS. 8 and 9A and 9B, the developing sleeve 41 includes a cylindrical sleeve main body 45 having a predetermined outer diameter D and a wall thickness t, and a predetermined surface on the surface of the sleeve main body 45. And a groove portion 46 as a rough surface portion provided so as to extend along the axial direction at intervals of the arrangement pitch p.
Here, the outer diameter D of the sleeve main body 45 is appropriately selected from about 12 to 20 mm, for example, and the wall thickness t is also appropriately selected from about 0.4 to 0.9 mm in consideration of the bending rigidity and the like.
Further, as shown in FIG. 9B, the groove portion 46 is formed of, for example, a V-shaped groove having a substantially V-shaped cross section, and in this example, an angle θ (for example, symmetrically arranged with respect to the radial line of the sleeve main body 45). 90-degree V-shaped groove, and has a deep groove configuration having a depth H (for example, 0.01 to 0.3 mm) and a groove width S (for example, 0.05 to 0.3 mm). And the arrangement pitch p of this groove part 46 is suitably selected, for example to about 0.3-1.5 mm.

In particular, in the present embodiment, the developing sleeve 41 is configured such that the groove width S of the groove portion 46 is increased from the axial center portion to the end portion of the sleeve main body 45 in substantially the same manner as in the first embodiment.
In the present embodiment, the groove 46 has a plurality of regions, for example, an A region including the central portion, a C region including the end of the sleeve main body 45, and a B region located between the A region and the C region. When the groove width S of each of the areas A to C is S (A), S (B), and S (C), S (A) <S (B) <S (C) is satisfied. It is set in stages.
In the present embodiment, the groove portion 46 divides the sleeve body 45 into three regions. However, the present invention is not limited to this, and the groove portion 46 is divided into more divided regions to appropriately adjust the change in the groove width S. You may make it do. In the first embodiment, the groove width S is changed. However, the present invention is not limited to this, and the depth H of the groove 46 may be changed, or both may be changed. Good.

Next, an example of a method for manufacturing the developing sleeve 41 used in the present embodiment will be described with reference to FIG.
In the figure, reference numeral 101 denotes a drawing die that is drawn for primary diameter reduction of the base tube 450 of the sleeve body 45, and 102 is a drawing die that applies a groove to the reduced diameter tube 451 drawn by the drawing die 101. is there.
Here, the drawing die 102 has a form in which the cutting members 104 corresponding to the respective groove portions 46 are arranged at the edge of the drawing opening 103. However, the movable cutting member 104 is movable in the radial direction in units of a plurality of cutting members 104. By having the mold 105 and moving the movable split mold 105 at an appropriate timing, groove portions 46 having different groove widths S are sequentially formed on the surface of the sleeve body 45. In this example, when the movable split mold 105 is moved, the groove width S and the depth H are also changed.
In this embodiment, the drawing die 101 and the drawing die 102 are used. However, the present invention is not limited to this, and a plurality of drawing dies are used, and at least one of the groove width S and the depth H of each groove portion 46. These may be formed sequentially. Further, in the present embodiment, the developing sleeve 41 is manufactured by drawing, and it is not particularly necessary to perform another process for improving the runout accuracy, but it is necessary to further improve the runout accuracy. In some cases, pre-processing or post-processing such as cutting and polishing may be performed before and after the drawing process.

Accordingly, even in the present embodiment, the groove width S (depth H) of the groove portion 46 of the developing roll 32 (developing sleeve 41) changes the gap (Gap) between the developing roll 32 and the layer thickness regulating member 33. Since it is variably set to a tendency opposite to the tendency, a large amount of developer passing through the gap is secured at a portion where the gap between the developing roll 32 and the layer thickness regulating member 33 is wide. On the other hand, the amount of developer transported by the groove 46 of the developing roll 32 is promoted at a portion where the gap is narrow, although the amount of developer passing through the gap is small.
For this reason, the developer conveyance amount distribution by the groove 46 of the developing roll 32 tends to cancel out the gap distribution. Therefore, the developer conveyance amount at the position in the developing roll axial direction is substantially constant as in the first embodiment. Set to

Embodiment 3
FIG. 11 shows the surface structure of the developing sleeve 41 of the developing device used in the image forming apparatus according to the third embodiment.
In the figure, the developing sleeve 41 has a concavo-convex pattern 46 formed on the surface of a sleeve body 45 as a rough surface portion. The uneven pattern 46 is manufactured by, for example, an etching process.
As shown in FIGS. 12 (a) and 12 (b), the concavo-convex pattern 46 has a convex block 51 having a regular shape and a concave groove 52 formed between the convex blocks 51.
In this example, the convex blocks 51 are, for example, equilateral triangles, and six are arranged in a diamond shape. The concave grooves 52 formed between these convex blocks 51 have a developing sleeve. 41 oblique grooves that are continuously arranged along an oblique direction including a circumferential component of 41 (in this example, a direction inclined by a predetermined angle α [for example, 60 ° or 120 °] with respect to the axial direction of the developing sleeve 41). 52 a and 52 b and an axial groove 52 c extending continuously along the axial direction of the developing sleeve 41.
Here, the depth h of the concave groove 52 refers to the distance from the flat portion of the convex block 51 to the bottom of the concave groove 52, the groove width w of the concave groove 52 refers to the upper end opening width of the concave groove 52, for example, Even if the bottom width of the groove 52 is different from the top opening width, the bottom width is irrelevant. In addition, although the vertical wall of the concave groove 52 in FIG. 12B is an inclined portion 53 that is inclined obliquely downward, this depends on the processing trace remaining in the manufacturing process (in this example, the degree of progress by the etching process). Processing trace).

In particular, in the present embodiment, the developing sleeve 41 is configured such that the concave-convex pattern 46 is made dense from the axial center to the end of the sleeve main body 45, as in the first embodiment.
In the present embodiment, the concavo-convex pattern 46 includes the sleeve main body 45 in a plurality of regions, for example, an A region including a central portion, a C region including an end of the sleeve main body 45, and a B positioned between the A region and the C region. When the concavo-convex pattern 46 in each of the areas A to C is 46 (A), 46 (B), and 46 (C), 46 (A) is the roughest, and 46 (B) and 46 (C ) Is gradually set so as to become denser.
In the present embodiment, the concave / convex pattern 46 divides the sleeve main body 45 into three regions. However, the present invention is not limited to this and may be divided into more divided regions.

Accordingly, even in the present embodiment, the density state of the uneven pattern 46 of the developing roll 32 (developing sleeve 41) is opposite to the change tendency of the gap (Gap) between the developing roll 32 and the layer thickness regulating member 33. Since the tendency is variably set, a large amount of developer passing through the gap is ensured at a portion where the gap between the developing roll 32 and the layer thickness regulating member 33 is wide, but the development with the concavo-convex pattern 46 of the developing roll 32 is ensured. On the other hand, in the portion where the gap is narrow, the amount of developer passing through the gap is small, but the amount of developer conveyed by the uneven pattern 46 of the developing roll 32 is promoted.
For this reason, since the developer transport amount distribution by the uneven pattern 46 of the developing roll 32 tends to cancel the gap distribution, the developer transport amount at the axial position of the developing roll 32 is substantially the same as in the first embodiment. It is set almost constant.

Embodiment 4
FIG. 13 shows a main part of the developing device of the image forming apparatus according to the fourth embodiment.
In FIG. 13, the developing device 30 includes a plate-like layer thickness regulating member 33 facing the developing roll 32 as shown in FIG. 13A, but is shown in FIGS. 13B and 13C. As described above, since the layer thickness regulating member 33 receives a force for pressing the developer when regulating the layer thickness of the developer, the layer thickness regulating member 33 is bent and deformed in the circumferential direction of the developing roll 32. Thus, if the layer thickness regulating member 33 is bent and deformed with the peak in the longitudinal direction (for example, δ), the relative positional relationship between the layer thickness regulating member 33 and the magnetic pole position of the magnet roll 42 of the developing roll 32 is different. Accordingly, the amount of developer passing through the layer thickness regulating member 33 differs.
Further, as shown in FIG. 13D, for example, when the layer thickness regulating member 33 has a round bar shape, the layer thickness regulating member 33 extends in the radial direction of the developing roll 32 with the central portion in the longitudinal direction as a peak. along bending deformation, the gap between the developing roller 32 and the layer thickness regulating member 33 (gap,) is different between the central portion and the end portion of the developing roller 32 (in FIG. _{13, g c> g e)} .

Therefore, in the present embodiment, as shown in FIG. 14A, in addition to the deflection amount of the developing sleeve 41 (developing roll 32), the deflection amount of the layer thickness regulating member 33 is taken into consideration, and the surface of the developing sleeve 41 It is sufficient to variably set the characteristics.
When the amount of bending of the developing sleeve 41 is small and the amount of bending of the layer thickness regulating member 33 is large, as shown in FIG. 14B, only the amount of bending of the layer thickness regulating member 33 is considered, The surface property of the developing sleeve 41 may be variably set.

Embodiment 5
FIG. 15A is an explanatory diagram schematically showing an image forming process of the image forming apparatus according to the fifth embodiment.
In the figure, in the image forming apparatus, a charging process by a charging device, an exposure process by a latent image writing device, and a developing process by a developing device (applying a developing bias to ensure developing contrast) are performed.
At this time, although the direct current component (DC component) of the developing bias is constant, the halftone potential corresponding to the halftone latent image after exposure, for example, is shown in FIG. There may be a non-uniform tendency as shown.
As shown in FIG. 15C, for example, in the aspect in which the latent image writing device 22 is a laser scanning device, the irradiation beam from the laser light source 22a is converted into a polygon mirror 22b and an imaging correction lens (fθ lens). The halftone potential is guided to the photosensitive drum 20 via the line 22c. However, the halftone potential changes to a non-uniform potential that continuously changes due to variations in irradiation of the polygon mirror 22b and variations in the imaging correction lens 22c. May be.
In the present embodiment, as shown in FIG. 16, the surface property of the developing sleeve 41 is set so as to correct the exposure characteristics of the latent image writing device 22 in consideration of the exposure characteristics.
In addition to the exposure characteristics, as indicated by a virtual line in FIG. 16, the surface property of the developing sleeve 41 is set in consideration of the bending amount of the developing sleeve 41 and the bending amount of the layer thickness regulating member 33. Of course, it may be.

Example 1
In this example, the developing sleeve of the developing device according to the first embodiment is used, and the surface roughness distribution, the gap distribution between the developing roll and the layer thickness regulating member, and the developer conveyance amount distribution are measured.
Here, the use conditions of the present embodiment are as follows.
Developing roll:
Outer diameter: 18mm
Blast width: 303mm
Sleeve length: 343mm
Sleeve material: Aluminum Sleeve thickness: 0.55mm
Magnetic pole pattern of developing roll: layer thickness regulating magnetic pole N ₁ provided corresponding to the layer thickness regulating member (peak value 84 mT, value 80 mT at the layer thickness regulating position indicated by ● in the figure), corresponding to the development area Provided development magnetic pole S ₁ (peak value 120 mT), transport magnetic pole N ₂ located downstream of the development magnetic pole S ₁ (peak value 77 mT), transport magnetic pole / pick-off magnetic pole S ₂ located downstream thereof (peak value 68 mT) Further, a magnet roll having a five-pole configuration of a transport magnetic pole / pickup magnetic pole S ₃ (peak value 45 mT) positioned on the downstream side was used (see FIG. 17).
Layer thickness regulating member:
Material: Stainless steel Shape: Round bar member with a diameter of 5 mm Image formation conditions:
Charging potential: 700V
Development bias DC component: 590V
Development bias AC component: rectangular wave, 900 Vp-p, 6 kHz
Photoconductor drum-developing roll gap: 0.40 mm
Photosensitive drum speed: 158 mm / s
Sleeve rotation speed: 316 mm / s

In this example, when the surface roughness Rz of the central portion (Center) and the end portions (In, Out) in the axial direction of the developing sleeve was measured a plurality of times, a tendency as shown in FIG. 18 was observed.
Further, when the relationship between the surface roughness Rz of the developing sleeve and the developer conveyance amount is examined, it is understood that the developer conveyance amount tends to be substantially proportional to the surface roughness Rz as shown in FIG.
Note that the developer transport amount is measured by developing the developer layered on the developing sleeve using a partitioning jig (opening area: 10 mm × 50 mm), with the longitudinal direction of the developing sleeve parallel to the side of 50 mm. The magnetic pole was partitioned so as to be on the center line of the partitioning jig, the developer was collected with a suction device, the weight was measured, and the weight per unit area was obtained. The concentration was measured using X-Rite (Spectrodensitometer; manufactured by X-Rite).
Furthermore, in the static state where the developing roll is not rotated, the gap between the developing sleeve (developing roll) and the layer thickness regulating member is substantially constant along the axial direction of the developing roll, as shown in FIG. In a dynamic state in which the developing roll rotates, the gap between the two tends to decrease toward both ends with a peak at the central portion in the axial direction.
However, in this embodiment, when the developer roll rotates, the amount of developer transported at each axial portion (axial center (Center) and end (In, Out)) of the developer roll is measured. As shown in FIG. 21, it is understood that the developer conveyance amount is substantially constant along the axial direction of the developing roll 32.
Furthermore, when the image density corresponding to each part in the axial direction of the developing roll was measured in a dynamic state in which the developing roll was rotated (for example, the developer conveyance amount was 450 g / m ² ), as shown in FIG. Is understood to be substantially constant along the axial direction of the developing roll.

◎ Comparative Example 1
In order to evaluate the performance of Example 1, performance tests were performed under the same conditions as in Example 1 using a developing sleeve having a uniform blast condition, and the results of FIGS. 23 to 25 were obtained.
According to FIG. 23, it is understood that the surface roughness Rz of the developing sleeve is substantially constant. At this time, in the static state in which the developing roll is not rotated, as shown in FIG. 24, in the dynamic state in which the developing roll rotates, even when the change in the gap between the developing roll and the layer thickness regulating member is not significantly changed, Similar to the first embodiment, the gap between the two tends to decrease toward both ends with a peak at the central portion in the axial direction.
In this state, in the dynamic state where the developing roll rotates, the developer conveyance amount at each axial portion (axial center (Center) and end (In, Out)) of the developing roll is measured. As shown in FIG. 4, there is a tendency that the developer conveyance amount becomes non-uniform along the axial direction of the developing roll.
Further, when the image density corresponding to each part in the axial direction of the developing roll was measured in a dynamic state in which the developing roll was rotated (the developer transport amount similar to that in Example 1), as shown in FIG. A tendency to become non-uniform along the axial direction of the developing roll is confirmed.

Example 2
In this example, the development sleeve of the developing device according to Embodiment 3 was used, and a performance test similar to that in Example 1 was performed.
The conditions of the uneven pattern of the developing sleeve are as follows.
Concave groove: Concave groove shown in FIG. 12 (b) Groove depth: 80 μm
Groove pitch: 1.0mm
According to the present embodiment, as shown in FIG. 27, it is understood that the groove width of the concavo-convex pattern of the developing sleeve changes along the developing roll axial direction.
At this time, it is understood that the relationship between the groove width of the concave groove and the developer conveyance amount is substantially proportional as shown in FIG.
Then, when the developer transport amount of the developing roll of this example was examined in a dynamic state in which the developing roll rotates, as shown in FIG. 29, the developer transport amount is substantially constant along the axial direction of the developing roll. It is understood that
Further, when the image density corresponding to each part in the axial direction of the developing roll was measured in a dynamic state in which the developing roll was rotated (for example, the developer conveyance amount was 550 g / m ² ), as shown in FIG. It can be seen that it is substantially constant along the axial direction of the developing roll.

Example 3
In this example, the same development test as that of Example 1 was performed using the developing sleeve of the developing device according to the second embodiment.
The conditions of the groove portion of the developing sleeve are as follows.
Groove: V-shaped groove Groove angle: 100 °
Groove pitch: 0.75mm
In this embodiment, when the relationship between the groove width of the groove (V-shaped groove) and the developer conveyance amount is examined, it is understood that the relationship is approximately proportional as shown in FIG.
Therefore, in this embodiment, as in the second embodiment, when the groove width of the groove portion (V-shaped groove) of the developing sleeve is set to change along the axial direction of the developing roll, the developer conveyance amount and the image density are set. Was confirmed to be substantially constant along the axial direction of the developing roll.

(A) is explanatory drawing which shows the outline | summary of the image forming apparatus which concerns on embodiment to which this invention is applied, (b) is the arrow view seen from the BB direction in (a), and the surface rough surface part of a developing sleeve FIG. 6 is an explanatory diagram schematically showing developer transport capability and developer transport amount in FIG. 1 is an explanatory diagram illustrating an overall configuration of an image forming apparatus according to a first embodiment. FIG. 3 is an explanatory diagram illustrating details of a developing device used in the first embodiment. (A) is explanatory drawing which shows the relative positional relationship of the developing sleeve (developing roll) and layer thickness control member of the developing device used in Embodiment 1, (b) is an arrow view seen from the B direction in (a). FIG. 4C is an explanatory view showing the operating state of the layer thickness regulating member. 3 is a surface structure of a developing sleeve used in the first embodiment. (A)-(c) is explanatory drawing which shows an example of the manufacturing method of the image development roll used in Embodiment 1. FIG. (A) is explanatory drawing which shows the relationship between a developing roll axial direction position and a developing roll-layer thickness regulation member gap, (b) is explanatory drawing which shows the relationship between a developing roll axial position and developing roll surface roughness, (c) ) Is an explanatory diagram showing the relationship between the position in the developing roll axial direction and the developer conveyance amount, and (d) is an explanatory diagram showing the relationship between the position in the developing roll axial direction and the developer conveyance amount in a comparative form. FIG. 6 is an explanatory diagram showing a surface structure of a developing sleeve used in Embodiment 2. (A) is sectional explanatory drawing of the developing sleeve of Embodiment 2, (b) is explanatory drawing which shows the groove part of a developing sleeve. 10 is an explanatory view showing an example of a method for manufacturing a developing sleeve used in Embodiment 2. FIG. FIG. 10 is an explanatory diagram showing a surface structure of a developing sleeve used in Embodiment 3. (A) is explanatory drawing which shows an example of the uneven | corrugated pattern of the image development sleeve used in Embodiment 3, (b) is explanatory drawing which shows the detail of the ditch | groove of an uneven | corrugated pattern. (A) is explanatory drawing which shows the relative positional relationship of the image development roll (developing sleeve) and layer thickness control member which are used in Embodiment 4, (b) is an arrow view seen from the B direction in (a), (c) is an arrow view seen from the C direction in (a), (d) is an explanatory view showing the relative positional relationship between the developing roll (developing sleeve) and the layer thickness regulating member used in the modified embodiment of the present embodiment. It is. (A) is explanatory drawing about the surface property setting of the developing sleeve used in Embodiment 4, (b) is explanatory drawing which shows the deformation | transformation form. (A) is explanatory drawing which shows an example of the image formation process performed with the image forming apparatus which concerns on Embodiment 5, (b) is explanatory drawing which shows the relationship between a developing roll axial direction position and a photoreceptor drum surface potential distribution, (C) is an explanatory view showing the generation factor of the photosensitive drum surface potential distribution. FIG. 10 is an explanatory diagram showing surface property setting of a developing sleeve used in Embodiment 5. 3 is an explanatory diagram illustrating an example of a magnetic pole pattern of a developing roll used in Example 1. FIG. In Example 1, it is explanatory drawing which shows the relationship between a developing roll axial direction position and the surface roughness Rz of a developing sleeve. In Example 1, it is explanatory drawing which shows the relationship between the surface roughness of a developing sleeve, and a developer conveyance amount. In Example 1, it is explanatory drawing which shows the relationship between a developing roll axial direction position and a developing roll-layer thickness control member clearance gap. In Embodiment 1, it is explanatory drawing which shows the relationship between a developing roll axial direction position and a developer conveyance amount. In Example 1, it is explanatory drawing which shows the relationship between a developing roll axial direction position and image density. In comparative example 1, it is explanatory drawing which shows the relationship between the developing roll axial direction position and the surface roughness Rz of a developing sleeve. In comparative example 1, it is explanatory drawing which shows the relationship between a developing roll axial direction position and a developing roll-layer thickness control member clearance gap. In Comparative Example 1, it is an explanatory diagram showing the relationship between the position in the developing roll axial direction and the developer conveyance amount. In Comparative Example 1, it is an explanatory diagram showing the relationship between the position in the developing roll axial direction and the image density. In Example 2, it is explanatory drawing which shows the relationship between a developing roll axial direction position and the groove width (groove width) of the uneven | corrugated pattern of a developing sleeve. In Example 2, it is explanatory drawing which shows the relationship between the said groove width and a developer conveyance amount. In Example 2, it is explanatory drawing which shows the relationship between a developing roll axial direction position and a developer conveyance amount. In Example 2, it is explanatory drawing which shows the relationship between a developing roll axial direction position and image density. In Example 3, it is explanatory drawing which shows the relationship between the groove width of the groove part (V-shaped groove) of a developing sleeve, and a developer conveyance amount.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Developing sleeve, 2 ... Sleeve main body, 3 ... Surface rough surface part, 5 ... Magnet member, 6 ... Developing container, 7 ... Developing roll, 8 ... Layer thickness regulating member, 11 ... Image carrier, 12 ... Developing device, g _c : a gap between the central portion of the developing sleeve (developing roll) and the layer thickness regulating member, g _e ... a gap between the end portion of the developing sleeve (developing roll) and the layer thickness regulating member, W: a developer conveying ability, M: Developer transport amount

Claims (7)

A developing container that can store a developer including toner and a carrier, a developing roll that is provided in the developing container and that can hold and convey the developer, and is opposed to the upper side of the developing roll in a non-contact state and developed. A layer thickness regulating member that regulates the layer thickness of the developer on the roll,
The developing roll includes a developing sleeve that holds and conveys the developer;
A magnetic member fixedly provided in the developing sleeve and having a plurality of magnetic poles arranged thereon,
Further, the developing sleeve includes a sleeve body formed of a nonmagnetic material,
The surface of the sleeve main body is roughened, and the surface rough surface portion is capable of changing the rough surface state in a tendency to reduce the difference in developer conveying ability that continuously changes along the axial direction of the sleeve main body. ,
The rough surface portion has an end portion from the central portion in the axial direction of the sleeve main body so as to reduce a difference in developer conveying ability corresponding to a deflection amount that changes along the axial direction of the sleeve main body facing the layer thickness regulating member. A developing device characterized in that the developer conveying capability is divided into three or more stages and gradually increased. The developing device according to claim 1,
The developing device according to claim 1, wherein the surface rough surface portion has a surface roughness that increases from a central portion in the axial direction of the sleeve body to an end portion. The developing device according to claim 1,
The rough surface portion has a groove portion extending along the axial direction of the sleeve body and capable of holding and transporting the developer, and the depth of the groove portion becomes deeper from the central portion of the sleeve body in the axial direction to the end portion. A developing device. The developing device according to claim 1,
The rough surface portion has a groove portion extending along the axial direction of the sleeve body and capable of holding and transporting the developer, and the width of the groove portion is widened from the central portion to the end portion in the axial direction of the sleeve body. A developing device. The developing device according to claim 1,
The rough surface portion is composed of a regular concavo-convex pattern having a convex block having a regular shape and a concave groove formed between the convex blocks, and the concavo-convex pattern extends from the central portion in the axial direction of the sleeve body to the end portion. And increasing the ratio of the recessed grooves. The developing device according to claim 1,
The surface rough surface portion is formed at the central portion in the axial direction of the sleeve body so as to reduce a difference in developer conveying ability corresponding to the deflection amount changing along the sleeve body and the deflection amount changing along the longitudinal direction of the layer thickness regulating member. A developing device characterized in that the developer conveying capacity is increased from the end to the end. Image holding member capable of holding an image, and development for visualizing an electrostatic latent image formed on the image holding member facing the image holding member with a developer containing toner and carrier An image forming apparatus comprising:
The developing device includes a developing container that can store a developer;
A developing roll provided in the developing container and capable of holding and transporting the developer;
A layer thickness regulating member that is disposed in a non-contact state on the upper side of the developing roll and regulates the layer thickness of the developer on the developing roll, and
The developing roll includes a developing sleeve that holds and conveys the developer;
A magnetic member fixedly provided in the developing sleeve and having a plurality of magnetic poles arranged thereon,
Further, the developing sleeve includes a sleeve body formed of a nonmagnetic material,
The surface of the sleeve main body is roughened, and the surface rough surface portion is capable of changing the rough surface state in a tendency to reduce the difference in developer conveying ability that continuously changes along the axial direction of the sleeve main body. ,
The rough surface portion has an end portion from the central portion in the axial direction of the sleeve main body so as to reduce a difference in developer conveying ability corresponding to a deflection amount that changes along the axial direction of the sleeve main body facing the layer thickness regulating member. An image forming apparatus characterized in that the developer conveying capability is divided into three or more stages and gradually increased.

Images