JP2002207366A - Developing device / image forming device - Google Patents

Abstract

(57) Abstract: A so-called lateral stirring in a developing device can be efficiently performed in a short time, and uniformity of image density can be obtained. An excess developer scraped off from a developing roller (not shown) by a doctor blade (not shown) rides on a separator 49 and is guided along a flow-down guide path 49b. The lengths of the openings 49e1, 49e2, and 49e3 for dropping the developer in the respective flow-down guide paths 49b are different, whereby the flow-down position of the developer in the axial direction of the developing roller is different. Since the developer having different flowing-down positions is mixed with each other and supplied to the developing roller by a paddle wheel (not shown) or the like is repeated, lateral stirring is promoted.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art In this type of image forming apparatus, a developing device supplies toner to a latent image formed on an image carrier to form a visible image, which is transferred to a sheet-like recording material such as paper. It has become. In a developing device used in such an image forming apparatus, in particular, a developing device using a developer including a carrier and a toner, the developer is carried on a developing sleeve as a developer carrying member, and is transported. Since toner is applied to the latent image on the body, the toner is consumed according to the latent image from the developer in the developing sleeve portion in the developing area which is the portion facing the image carrier. Since the potential distribution of the latent image in the axial direction of the image carrier is generally non-uniform, toner consumption from the developer on the developing sleeve also becomes non-uniform,
The developer in the developing sleeve portion that has returned to the developing device after passing through the developing area has a difference in toner density in the axial direction of the developing sleeve. Therefore, in order to continuously perform good development, it is necessary to agitate the developer in the developing device in the axial direction of the developing sleeve, that is, so-called “lateral stirring” of the developer.

[0003] As a lateral stirring mechanism of the developer, for example,
As described in JP-A-5-2333, the developer scraped off from above the developing sleeve by a doctor blade as a developer regulating member flows down (drops).
There is known a method using a separator as a developer flowing-down member. The separator has a plurality of fins on its upper surface, thereby forming a plurality of flow-down guide paths. Each fin is arranged so as to make the developer skew (move obliquely) with respect to a direction orthogonal to the axial direction of the developing sleeve. For this reason, the developer is guided to a place separated from the developing sleeve while being displaced in the axial direction of the developing sleeve, and falls. The dropped developer is pumped up while being stirred by a developer supply member such as a paddle wheel, and is supplied to the developing sleeve again. By skewing the developer on the separator, horizontal stirring is performed as opposed to so-called vertical stirring by the developer supply member.

Japanese Patent Application Laid-Open No. 6-83195 discloses that the developer at the far end in the oblique direction (for example, the far end in the axial direction of the developing sleeve) of the separator is conveyed by a stirring screw in the direction opposite to the direction of displacement due to oblique movement. This document describes a configuration that enhances the function of lateral stirring by dropping the liquid. In any of the above configurations, the inclination of the adjacent fins and the distance from the developing sleeve at the downstream position are the same, and after skewing along each fin from above the separator, the developer is substantially parallel to the axis of the developing sleeve. It falls on the line.

[0005]

As described above, in the conventional configuration, the developer gradually moves in the axial direction of the developing sleeve due to the inclination of the fin, and the developer reaching the inner end of the separator is stirred by the stirring screw. Is transported to the near side in the opposite direction and falls. As a result, the developer is mixed while circulating, and lateral stirring is performed. However, the developer divided into fins on the separator, except for the one that is conveyed to the near side by the stirring screw at the end, moves evenly in the axial direction of the developing sleeve by the same distance and drops, so the horizontal stirring It takes a long time, and there is a problem that the image density becomes non-uniform in performing the development continuously.

As described above, since the developer is evenly shifted in the axial direction of the developing sleeve by the separator and the fins, the developer is circulated with the width of the region having a low concentration substantially unchanged, resulting in inefficient lateral stirring. I was This is shown in FIG. FIG. 10A shows a state in which the toner density is shifted to output a black pattern on the entire surface. In FIG. 10A, the downward direction is the printing direction. Hatching indicates black, and dots indicate a low density state. In the area Y where the toner density is low, the image density is also output lightly. FIGS. 10B and 10C show that the developer is uniformly moved in the direction of the drawing by the fins.
This shows a state in which the low density region Y moves with substantially the same width. The concentration gradually increases due to lateral stirring or the like.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a developing device capable of performing horizontal stirring in a short time and efficiently and obtaining uniformity of image density, and an image forming apparatus provided with the developing device. .

[0008]

In order to achieve the above object, according to the first aspect of the present invention, there is provided a developer carrier for conveying a developer to develop a latent image formed on an image carrier. A developing container for storing a developer for supplying to the developer carrier, a developer supply member for supplying the developer in the developing container to the developer carrier, and a developer on the developer carrier. In a developing device having a developer regulating member that regulates to a thickness suitable for development, and a developer flowing-down member that causes the developer scraped by the developer regulating member to flow down to a location away from the developer carrier, The configuration is such that the developer flowing position on the developer flowing member is different in the axial direction of the developer carrying member.

According to a second aspect of the present invention, in the developing device according to the first aspect, the developer flow-down member causes the developer to skew in a direction orthogonal to an axial direction of the developer carrier. Is provided.

According to a third aspect of the present invention, in the developing device according to the second aspect, the plurality of flow-down guide paths have alternately different flow-down positions.

According to the fourth aspect of the present invention, the first to third aspects are provided.
In the developing device according to any one of the above, a developer transport path extending in the axial direction of the developer carrier is provided at a downstream end portion of the developer flowing member in the downstream direction, and the developer transport path is A configuration in which a developer conveying member that communicates with the rear end portion of the developer flowing-down direction in the oblique direction and that conveys the developer in a direction opposite to the direction of displacement by the oblique direction is provided in the developer conveying path. Has been adopted.

According to a fifth aspect of the present invention, in the developing device according to the fourth aspect, a notch portion for overflowing the developer is provided in the developer conveying path.

According to the sixth aspect of the present invention, a developer carrier for transporting the developer to develop the latent image formed on the image carrier, and a developer for supplying the developer carrier to the developer carrier are stored. A developer container, a developer supply member for supplying the developer in the developer container to the developer carrier, and a developer regulating member for regulating the developer on the developer carrier to a thickness suitable for development. A developing device having a developer flow-down member for flowing the developer scraped off by the developer regulating member to a location distant from the developer carrying member; A plurality of flow-down guide paths that obliquely move in a direction perpendicular to the axial direction of the developer carrier, and extend in the axial direction of the developer carrier at the downstream end of the developer flow member in the flow-down direction; A developer transport path is provided, and the developer transport path is the developer flow-down section. The developer conveying path is provided with a developer conveying member which communicates with the developer conveying path in a direction opposite to the direction of skew displacement. It has a configuration in which a notch is formed to overflow.

According to a seventh aspect of the present invention, in the image forming apparatus, the latent image formed on the image carrier is visualized by a developing device, and the visible image is transferred to a recording material to form an image. The developing device is configured as described in one of claims 1 to 6.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. As shown in FIG. 1, an image forming apparatus according to the present embodiment includes a photosensitive drum 1 as an image carrier.
And a developing device 4 and the like. Around the photoreceptor drum 1, a charging roller 2 as a charging means for uniformly charging the surface of the photoreceptor drum 1, and a latent image on a charging-processed surface of the photoreceptor drum 1 by a laser beam 3 based on image information. A developing unit 4 for forming a toner image by adhering a charged toner to a latent image formed on the photosensitive drum 1, and a toner forming unit on the photosensitive drum 1. Belt-type transfer means 5 for transferring an image onto paper P as a recording material, cleaning means 7 for removing toner remaining on photoconductor drum 1 after transfer, and removal of residual potential on photoconductor drum 1 There are provided static elimination means 8 and the like. The transfer unit 5 includes a transfer belt 5a, a driving roller 5b, a driven roller 5c as a bias roller, a tension roller 5d, and the like. The cleaning means 7 includes a casing 7a, a cleaning blade 7b supported by the casing 7a, a cleaning brush 7
and a transport screw 7d for transporting the removed toner to a waste toner tank or a recycling mechanism (not shown).

The photosensitive drum 1, whose surface is uniformly charged by the charging roller 2, forms an electrostatic latent image by the exposure light 3 and forms a toner image by the developing device 4. The toner image is transferred by the transfer unit 5 onto a sheet P fed from a sheet feeding unit (not shown). The sheet P to which the toner image has been transferred is sent to a fixing unit (not shown), where the toner image is fixed by heat and pressure. The toner remaining on the photosensitive drum 1 without being transferred is collected by the cleaning unit 7. The photoreceptor drum 1 from which the residual toner has been removed is initialized by the charge removing means 8, and is used for the next image forming process.

Next, the developing device 4 will be described in detail with reference to FIG. The developing device 4 includes a developing container unit 4A and a toner replenishing unit 4B. In the developing container section 4A,
The developing roller 41 as a developer carrier is a photosensitive drum 1
, And a developing region D is formed in a portion facing the both. A doctor blade 45 as a developer regulating member that regulates the amount (layer thickness) of the developer on the developing roller 41 is disposed at the upstream side of the developing region D in the developer conveying direction, that is, the counterclockwise direction. ing. A stirring roller 46 and a paddle wheel 47 are provided on the right side of the developing roller 41 in the drawing. The developer is agitated by the agitating roller 46 and is pumped up to the developing roller 41 by the paddle wheel 47. The developing container 51 is disposed below so as to surround the stirring roller 46, the paddle wheel 47, and the like.

In the toner replenishing section 4B, for example, when the toner density sensor 48 detects that the density of the toner supplied to the photosensitive drum 1 has decreased, the toner replenishing roller 4B
B <b> 1 rotates to feed the toner T toward the stirring roller 46. In the vicinity of the doctor blade 45, a separator 49 is provided as a developer flow-down member which extends to the upper portion of the stirring roller 46 and is inclined so as to descend toward the stirring roller 46. Separator 4
Reference numeral 9 includes a plurality of fins 49a arranged at intervals in the axial direction of the developing roller 41. At the downstream end (end on the stirring roller 46 side) of the separator 49 in the downstream direction, a developer transport path 49c extending in the axial direction of the developing roller 41 is formed, and the developer is skewed in the developer transport path 49c. A rotatable transport screw 50 is provided as a developer transport member that transports the developer in a direction opposite to the direction of displacement caused by the developer.

As shown in FIGS. 3 and 4, a plurality of fins 49a are provided at an angle, so that the developer is supplied between the fins 49a in a direction perpendicular to the axial direction of the developing roller 41. A flow guideway 49b is formed to skew. As shown in FIG. 3, a developer guide path 49 g is formed at the far end in the oblique direction of the separator 49 (the far end in the direction in which the developer is displaced by the oblique movement). Communicating. The developer is pumped up by the rotation of the paddle wheel 47 and is discharged toward the developing roller 41. The discharged developer is a developing roller 41
Carried on the surface of The carried developer is a developing roller 4
It moves with the rotation of 1 and the layer thickness is regulated by the doctor blade 45. Excess developer scraped by the doctor blade 45 is guided by the plurality of flow-down guide paths 49b on the separator 49, and is conveyed while sequentially moving (displaced) to the back side of the image forming apparatus (in the direction of arrow R). Is done.

The developer transported to the back of the image forming apparatus enters the developer transport path 49c via the developer guide path 49g, and is moved in the opposite direction (the direction of arrow F) by the transport screw 50.
Is transported to the front side of the image forming apparatus. Developer transport path 49
A slit 49d is formed at a position facing the stirring roller 46 on the front side of the image forming apparatus c, and the developer transported by the transport screw 50 falls onto the stirring roller 46 from the slit 49d. By transporting the developer before and after (in the directions of the arrows R and F), the toner is stirred so that the toner concentration becomes uniform in the longitudinal direction of the image forming apparatus, and at the same time, the transport amounts of the developer before and after are set equal. By doing so, it is possible to maintain the water level of the developer constant.

As shown in FIG. 4, the separator 49 according to the present embodiment is configured such that the developer flowing down position corresponds to the developing roller 41.
In the axial direction. That is, openings 49e1, 49e2, and 49e3 for dropping the developer are formed in each of the flow-down guide paths 49b, and these openings 49e1, 49e2, and 49e3 are respectively provided from the developing roller 41 side to the developer conveying path 49c. Distances are different. The opening 49e having the longest distance
In the case of 1, the developer that has entered the flow-down guide path 49b falls immediately at a stage where the amount of movement to the back side of the image forming apparatus is small.
In the opening portion 49e3 having the shortest distance, as in the related art, the developer that has entered the flow-down guide path 49b moves to the back of the image forming apparatus and then falls immediately before the developer transport path 49c. Since the developers having different movement amounts to the back side of the image forming apparatus are circulated in the front-rear direction while being mixed with each other, lateral stirring is promoted. In the present embodiment, three types of openings 49e1, 4
9e2 and 49e3 are repeated in the axial direction of the developing roller 41 (this configuration is omitted in FIG. 3).

Next, another embodiment will be described with reference to FIG. Note that the same parts as those in the above embodiment are denoted by the same reference numerals,
Unless otherwise required, the description of the configuration and the function already described is omitted (the same applies to other embodiments described below). The present embodiment is characterized in that the flow-down positions in the flow-down guide path 49b are alternately different. That is, 2
The openings 49e1 and 49e3 are alternately repeated in the axial direction of the developing roller 41. FIG.
FIGS. 7A and 7B show how the toner concentration TC on the developing roller 41 changes in the present embodiment in comparison with the conventional method. FIG. 7A shows a change in the conventional method, and FIG. 7B shows a change in the present embodiment. I have.

In the figure, R indicates the position on the back side of the image forming apparatus, and F indicates
Indicates the position on the near side, and C indicates the position of the center. The initial TCs are 4% and 1% and are uniform at 2.5%.
In the conventional method (a), the developer is simultaneously conveyed to the back side,
On the other hand, since the sheet is conveyed from the rear end to the front end via the developer conveying path, a phenomenon in which the light and shade of R and F are switched occurs, and it takes time to converge. In the case of the present embodiment, it can be seen that the above-described switching phenomenon does not occur and the convergence is achieved in a short time. That is, it can be seen that lateral stirring is promoted as compared with the conventional method.

FIG. 7 shows a state in which the toner density is shifted in the same manner as in FIG. 10 to output a black pattern on the entire surface in this embodiment. In the figure, the downward direction is the printing direction. Hatching indicates black, and dots indicate a low density state. In the area Y where the toner density is low, the image density is also output lightly. However, as shown in FIGS. 8B and 8C, the low-density region Y gradually narrowed and became uniform in a short time.

Next, another embodiment will be described with reference to FIG. In the present embodiment, as in the conventional method, only the opening 49e3 for dropping the developer immediately before the developer conveying path 49c is formed in each of the flow-down guide paths 49b. The developer transport path 49c is provided with a notch 49f that overflows the developer during transport. The developer overflowing from the notch portion 49f is immediately conveyed onto the separator 49 by the stirring roller 46 and the paddle wheel 47, and flows down the guide path 49b.
Circulates back and forth while mixing with the
Mixing of the developer (lateral stirring) is promoted.

FIG. 9 shows another embodiment in which the structure shown in FIG. 5 in which the flow-down positions are alternately different and the structure shown in FIG. 8 in which the developer conveying path 49c has a cutout portion 49f are combined. . In the present embodiment, in addition to the good mixing due to the different flow-down positions, the mixing promoting function of the cutout 49f can be obtained at the same time, so that the horizontal stirring can be further promoted.

[0027]

According to the first or seventh aspect of the present invention, the position of the developer flowing down on the developer flowing-down member is different in the axial direction of the developer carrying member. This can be performed efficiently in a short time, and uniformity of image density can be obtained.

According to the second or seventh aspect of the present invention, the developer flow-down member has a plurality of flow-down guide paths for causing the developer to skew in a direction orthogonal to the axial direction of the developer carrier. With this configuration, lateral stirring can be enhanced with high accuracy.

According to the third or seventh aspect of the present invention, the flow-down positions of the plurality of flow-down guide paths are alternately different, so that lateral stirring can be performed efficiently in a short time. Image density uniformity can be obtained.

According to the fourth or seventh aspect of the present invention, a developer transport path extending in the axial direction of the developer carrier is provided at the downstream end of the developer flowing member in the downstream direction. Communicates with the back end in the oblique direction of the developer flowing-down member, and the developer conveying path is provided with a developer conveying member that conveys the developer in a direction opposite to the direction of displacement by the oblique movement. Therefore, mixing in the axial direction (front-back direction) of the developer carrying member can be enhanced, and the lateral stirring function can be further enhanced.

According to the fifth or seventh aspect of the present invention, since the notch portion for overflowing the developer is provided in the developer conveying path, the lateral stirring function can be further enhanced.

According to the invention described in claim 6 or 7, the developer flow-down member has a plurality of flow-down guide paths for skewing the developer in a direction orthogonal to the axial direction of the developer carrying member. A developer conveying path extending in the axial direction of the developer carrier is provided at a downstream end of the developer flowing-down member in a flow-down direction, and the developer conveying path is an obliquely rear end of the developer flowing-down member in the oblique direction. The developer transport path is provided with a developer transport member that transports the developer in a direction opposite to the direction of displacement due to skewing, and the developer transport path has a cutout that overflows the developer. With this configuration, the horizontal stirring function can be enhanced even if the developer flowing position on the developer flowing member is the same in the axial direction of the developer carrying member.

[Brief description of the drawings]

FIG. 1 is a schematic front view of an image forming apparatus according to an embodiment of the present invention.

FIG. 2 is a schematic enlarged front view of the developing device.

FIG. 3 is a schematic plan view of a separator.

FIG. 4 is a schematic perspective view of a separator.

FIG. 5 is a schematic perspective view of a separator according to another embodiment.

FIG. 6 is a graph showing how the toner density changes;
(A) shows the case of the conventional system, and (b) shows the case of the embodiment shown in FIG.

FIG. 7 is a diagram showing a state of movement of a developer by a fin in the embodiment shown in FIG. 5;

FIG. 8 is a schematic perspective view of a separator according to another embodiment.

FIG. 9 is a schematic perspective view of a separator according to another embodiment.

FIG. 10 is a diagram illustrating a state of movement of a developer by a fin in a conventional method.

[Explanation of symbols]

 Reference Signs List 1 photoconductor drum 41 as image carrier 41 developing roller as developer carrier 45 doctor blade as developer regulating member 47 paddle wheel as developer supply member 49 separator 49b as developer flowing member 49b flow guide path 49c Developer transport path 49f Notch 50 Transport screw as developer transport member 51 Developing container

Claims (7)

[Claims] A developer container for transporting the developer to develop a latent image formed on the image carrier; a developing container for storing a developer to be supplied to the developer carrier; A developer supply member for supplying the developer in the developing container to the developer carrier, a developer regulating member for regulating the developer on the developer carrier to a thickness suitable for development, and the developer regulating member In a developing device having a developer flow-down member for flowing down the developer scraped by the developer away from the developer carrier, the flow-down position of the developer on the developer flow-down member is
A developing device, wherein the developer carrier is different in the axial direction. 2. The developing device according to claim 1, wherein the developer flow-down member includes a plurality of flow-down guide paths for skewing the developer in a direction perpendicular to an axial direction of the developer carrier. A developing device, comprising: 3. The developing device according to claim 2, wherein the plurality of flow-down guide paths have different flow-down positions alternately. 4. A developing device according to claim 1, wherein said developer carrying member extends axially of said developer carrier at a downstream end of said developer flowing member. The developer conveying path communicates with the obliquely deep end of the developer flowing-down member, and the developer conveying path conveys the developer in a direction opposite to the direction of the oblique displacement. A developing device comprising a transport member. 5. The developing device according to claim 4, wherein a notch portion for overflowing the developer is provided in the developer conveying path. 6. A developer carrier for conveying a developer to develop a latent image formed on the image carrier, a developing container for containing a developer to be supplied to the developer carrier, and A developer supply member for supplying the developer in the developing container to the developer carrier, a developer regulating member for regulating the developer on the developer carrier to a thickness suitable for development, and the developer regulating member A developing device having a developer flow-down member for causing the developer scraped off by the developer to flow to a location distant from the developer carrier, wherein the developer flow-down member moves the developer in the axial direction of the developer carrier. A plurality of flow-down guide paths obliquely inclined with respect to a direction perpendicular to the direction, and a developer conveyance path extending in the axial direction of the developer carrying member is provided at a downstream end of the developer flow-down member in the flow-down direction. The developer conveying path communicates with the obliquely back end of the developer flow-down member. The developer transport path is provided with a developer transport member for transporting the developer in a direction opposite to the direction of skew displacement, and the developer transport path is provided with a notch for overflowing the developer. A developing device. 7. An image forming apparatus for visualizing a latent image formed on an image carrier by a developing device and transferring the visible image to a recording material to form an image. An image forming apparatus according to any one of Items 1 to 6.