JP3611281B2 - Powder conveying device, developing device, and image forming apparatus including these - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for conveying powder supplied into a housing and discharging the powder to the outside of the housing, for example, a powder conveying apparatus such as a developing device used in an electrophotographic image forming apparatus. It is.
[0002]
[Prior art]
In an image forming apparatus using a conventional electrophotographic system, development is performed by applying a developer, which is a powder, to an electrostatic latent image formed on the surface of an image carrier such as a photoconductor by a developing device that is a powder conveying device. Then, it is visualized as a toner image, and this developing device is configured as follows.
[0003]
As shown in FIG. 9, the conventional developing apparatus has a developing container 104 as a housing that is partitioned into a stirring chamber 104a and a developing chamber 104b by a partition wall 106, and is provided in an opening 104c above the developing chamber 104b. The developing roller 101 is rotatably supported so as to face the photosensitive drum 100 of the image forming apparatus. The developing roller 101 is used for development by rotating in a direction indicated by an arrow with respect to the rotating photosensitive drum 100 by a drive system (not shown).
[0004]
A screw 103 and a screw 102, which are screw bodies, are rotatably provided in the stirring chamber 104a and the developing chamber 104b, respectively. A sealant (felt or the like) 107 that prevents developer leakage is pressed against both ends of the developing roller 101 and supported by the developing container 104.
[0005]
In the developing device as described above, the screw 103 in the stirring chamber 104a is rotated by being driven by a drive system (not shown), and as shown in FIG. 10 showing a cross section along line A′-A ′ of FIG. The developer in the developing container 104 is conveyed in the direction of the arrow V ′ while being agitated with the toner replenished into the stirring chamber 104a from the toner replenishing port 104d at the opening on the front side of the developing container 104, and this developer is further conveyed to the partition wall. The toner is transferred into the developing chamber 104b through the opening 106a at the tip position in the direction of arrow V 'of 106. Similarly, the screw 102 in the developing chamber 104b is rotated by being driven by a drive system (not shown), and the developer transferred from the stirring chamber 104a to the developing chamber 104b in the direction opposite to the arrow V ′. The developer is conveyed in the W ′ direction, and the developer is returned to the stirring chamber 104 a through the opening 106 b at the tip end position of the partition wall 106 in the arrow W ′ direction.
[0006]
Then, the developer in the developing chamber 104b is pumped up by the rotating developing roller 101 while being conveyed in the direction of the arrow W ′ by the screw 102, and is regulated by the regulation at the blade 105 close to the developing roller 101. The developer layer having a predetermined layer thickness is formed on the developing port 101 by coating with a layer thickness. Further, as the developing roller 101 rotates, the toner is conveyed to the position of the opening 104c of the developing chamber 104b, where the developer is supplied to the photosensitive drum 100 and toner is applied to the electrostatic latent image formed on the surface of the photosensitive drum 100. The image is adhered and developed, and the electrostatic latent image is visualized as a toner image.
[0007]
As shown in FIG. 9, positioning with the photosensitive drum is performed by abutting an abutting roller 108 on the shaft of the developing port 101 with an abutting roller 109 fixed to the front and rear side plates 110 and 111. Do.
[0008]
Both ends of the screws 102 and 103 are supported by the developing container 104 by shaft seals 112a, 113a, 114a, and 115a and bearings 112b, 113b, 114b, and 115b, respectively. From the viewpoint of toner intrusion into the shaft seal portion and prevention of scattering of the developer from the replenishing port 104d, the developer is fed from the end of the developer container 104 to the ends of the screws 102 and 103 in the transport direction as shown in FIG. Sub-conveying sections 102a and 103a, which are sub-conveying means, are provided for reverse feeding.
[0009]
[Problems to be solved by the invention]
However, according to the above-described conventional example, when the developer makes a U-turn from the W ′ direction to the V ′ direction with the screw 102, the developer conveyance force in the Y ′ direction from the sub conveyance unit 102 a is also applied, and the conveyance unit and the sub conveyance unit The developer pressure at the merging portion J increases, and there is a possibility that the developer agglomerates at the merging portion J.
[0010]
The developer agglomeration lowers the screw conveyance capability, leading to a decrease in the density of the developer supplied to the developing roller 101, and the aggregated particles are caught in the gap between the blade 105 and the developing roller 101, resulting in white streaks. There is a possibility that the aggregated particles adhere to the output image and the image quality is remarkably deteriorated.
[0011]
SUMMARY An advantage of some aspects of the invention is that it provides a powder conveying device, a developing device, and an image forming apparatus including the powder conveying device that can convey powder such as developer in a housing without agglomeration.
[0012]
[Means for Solving the Problems]
According to the present application, the above object is related to the powder conveying device, toward the housing for accommodating the powder, the main conveying means for conveying the powder in the housing in a predetermined direction, and the conveyance end of the main conveying means. possess a secondary conveying means for conveying the powder in the housing in the predetermined direction and the opposite direction, the main transport means and auxiliary transport means, reduce the powder conveying force at the junction between the main conveying means and the sub-carrier means In the powder conveying apparatus, the main conveying means and the sub conveying means are rotatable screw bodies including screw blades, and the screw blades are directed toward the connecting portion between the main conveying means and the sub conveying means. This is achieved by the first invention in which the diameter of each of these is gradually reduced .
[0014]
Further, according to the present application, above objects, in a first aspect, the main transport means and auxiliary transport means, the connecting portion between the main conveying means and the sub-carrier means is in the not cut portion of the screw blade This is also achieved by the second invention.
[0016]
Further, according to the present application, the object of the developing device is a developing device that visualizes the latent image by applying a developer that is a powder contained in a developing container as a housing to the latent image. It is also achieved by the third invention comprising the powder conveying device of the first invention.
[0018]
Further, according to the present application, the object is achieved, in the third invention, the main transport means and auxiliary transport means, the connecting portion between the main conveying means and the sub-carrier means is in the not cut portion of the screw blade This is also achieved by the fourth invention.
[0020]
Further, according to the present application, the object is related to the image forming apparatus, which is an image forming apparatus for recording an image formed by a series of image forming processes on a recording medium, the powder conveying apparatus according to the first invention. Alternatively, it is also achieved by a fifth invention comprising the developing device of the third invention.
[0022]
Further, according to the present application, in the fifth invention, the main transport means and the sub-transport means have a notch portion without a screw blade at the connection between the main transport means and the sub-transport means. This is also achieved by the sixth invention.
[0024]
That is, in the first , third, and fifth inventions according to the present application, the rotatable main transporting means and sub-transporting means, which are screw bodies including screw blades, transfer the powder in the housing to the main transporting means. The developer conveying force is reduced in accordance with the diameter of the screw blade toward the connecting portion between the screw and the sub conveying means.
[0026]
In the second, fourth, and sixth inventions according to the present application, the rotatable main transporting means and sub-transporting means, which are screw bodies including screw blades, transfer the powder in the housing to the main transporting means. The developer conveying force is reduced by the cutout portion of the connecting portion between the second conveying means and the auxiliary conveying means.
[0036]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to FIGS. 1 to 7 of the accompanying drawings.
[0037]
(First embodiment)
First, the image forming apparatus 20 according to the first embodiment of the present invention will be described with reference to FIGS. 1 to 4. In the present embodiment, the powder conveyance device of the present invention is applied to a developing device used in an electrophotographic image forming apparatus.
[0038]
As shown in FIG. 1, such an image forming apparatus has a photosensitive drum 22 which is a drum-shaped rotatable photosensitive drum 22 as a latent image carrier, a developing device 24, and an exposure process corresponding to image information from an image information providing device. A laser scanner unit 21 for forming an electrostatic latent image according to the image information on the outer peripheral surface of the drum 22 and a roll-shaped rotatable transfer roller 25 for performing a transfer process on the transfer material P as a recording medium. And a fixing device 27 configured to perform a fixing process on the transfer material P after the transfer process by heating and pressing.
[0039]
In the image forming apparatus 20, first, the laser scanner unit 21 exposes the outer peripheral surface of the photosensitive drum 22 charged to a specified potential by the charging body 23, and is given to the image forming apparatus 20 from the outside. An electrostatic latent image corresponding to the image information is formed on the outer peripheral surface.
[0040]
Next, the electrostatic latent image formed on the outer peripheral surface of the photosensitive drum 22 is visualized as a visible image by applying a developer as powder from the developing device 24.
[0041]
On the other hand, the transfer material P on which image information corresponding to the given image information is recorded is fed to a transfer nip TN formed between the photosensitive drum 22 and the transfer roller 25 at a predetermined timing. The
[0042]
Therefore, the transfer material P that has reached the transfer nip portion TN is formed on the outer peripheral surface of the photosensitive drum 22, and the carried visible image is transferred by electrical interaction from the transfer roller 25.
[0043]
Next, the transfer material P on which the visible image is carried on one surface in an unfixed state (hereinafter, the visible image in the unfixed state is referred to as an unfixed image) is conveyed to the fixing device 27 and is then fixed. In this case, the unfixed image is melted and fixed by applying heat and pressure in the transfer material P. Therefore, the transfer material P records an image corresponding to the applied image information, and the transfer material P on which the image is formed is recorded. Is discharged onto a discharge tray 29 disposed in the printer main body by a pair of discharge rollers 30.
[0044]
As shown in FIG. 2, the developing device 24 has a developing container 4 serving as a housing that is partitioned into a stirring chamber 4a and a developing chamber 4b by a partition wall 6 and is provided in an opening 4c above the developing chamber 4b. The developing roller 1 is rotatably supported so as to face the photosensitive drum 22 of the image forming apparatus. The developing roller 1 is used for development by rotating in a direction indicated by an arrow with respect to the rotating photosensitive drum 22 by a drive system (not shown).
[0045]
A screw 2 and a screw 3 that are screw bodies are rotatably provided in the stirring chamber 4a and the developing chamber 4b, respectively. Sealing material (felt or the like) 7 for preventing developer leakage is pressed against both ends of the developing roller 1 and supported by the developing container 4.
[0046]
In the developing device as described above, the screw 3 in the stirring chamber 4a is rotated by being driven by a drive system (not shown), and as shown in FIG. 3 showing a cross section along line AA in FIG. The developer in the container 4 is conveyed in the direction of arrow V while being agitated with the toner replenished into the stirring chamber 4a from the toner replenishing port 4d at the opening on the front side of the developing container 4, and this developer is further conveyed in the direction of the arrow of the partition wall 6. The toner is transferred into the developing chamber 4b through the opening 6a at the tip in the V direction. Similarly, the screw 2 in the developing chamber 4b is rotated by being driven by a driving system (not shown), and the developer transferred from the stirring chamber 4a to the developing chamber 4b is transferred in the direction W opposite to the arrow V. The developer is returned to the stirring chamber 4a through the opening 6b at the tip of the partition wall 6 in the arrow W direction.
[0047]
The developer in the developing chamber 4 b is pumped up by the rotating developing roller 1 when being conveyed in the direction of arrow W by the screw 2, and is controlled by a blade 5 adjacent to the developing roller 1 to a predetermined layer. A developer layer having a predetermined layer thickness is formed on the developing port 1 by being applied to a thickness. Further, as the developing roller 1 rotates, the developer is conveyed to a position of the opening 4c of the developing chamber 4b, where the developer is supplied to the photosensitive drum 22 and toner is applied to the electrostatic latent image formed on the surface of the photosensitive drum 22. The image is adhered and developed, and the electrostatic latent image is visualized as a toner image.
[0048]
As shown in FIG. 3, the positioning with the photosensitive drum is performed by abutting the abutting roller 8 on the shaft of the developing port 1 with the abutting roller 9 fixed to the front and rear side plates 10 and 11. Do.
[0049]
Both ends of the screws 2 and 3 are supported by the developing container 4 by shaft seals 12a, 13a, 14a and 15a and bearings 12b, 13b, 14b and 15b, respectively. From the viewpoint of toner intrusion into the shaft seal portion and prevention of scattering of the developer from the replenishing port 4d, the developer is fed back from the end of the developer container 4 as shown in FIG. Sub-transport portions 2a and 3a, which are sub-transport means, are provided for feeding.
[0050]
In the present embodiment, the screw 2 and the screw 3 are supported so as to be rotatable with respect to the developing container 4. In addition, screw-shaped screw blades 2 'and 3' are provided on the outer circumferences of the screw 2 and the screw 3, respectively, thereby conveying the developer in the W and V directions, respectively. Further, a sub-conveying portion 2b having spiral blades 2 ″ having a pitch opposite to that of the main conveying portion 2a that conveys the developer in the W direction is provided at the conveyance end portion of the screw 2. The developer is conveyed in the Y direction opposite to the W direction, and an upper portion of the sub-conveying unit 2b has a replenishing port for replenishing toner as powder in the developing container 4, from which a hopper device or the like ( The toner is replenished by (not shown).
[0051]
A boundary portion between the main conveyance container 2a and the sub conveyance unit 2b is provided with a notch 2c having no screw blades, that is, having no conveyance ability. Since the conveyance force is applied in the W direction in the area of the main conveyance part 3a and in the Y direction in the area of the sub conveyance part 3b, the compression force applied to the developer is maximized at the boundary part, but is pressed by the notch part 2c. The force does not increase abruptly, the developer is directed in the direction of the B screw 3 without being restrained, and is conveyed in the V direction by the B screw 3. Therefore, the developer can be smoothly circulated without causing the developer to stay at the boundary due to the conveyance pressure.
[0052]
Therefore, according to the present embodiment, the screws 2 and 3 including the screw blades 2 ′ and 3 ′ remove the developer in the developer container 4 from the notch at the boundary between the main transport unit 2 a and the sub transport unit 2 b. Since the developer conveying force is reduced by 2c, the developer is not excessively compressed at the boundary portion, and the developer can be smoothly conveyed while suppressing aggregation of the developer at the boundary portion.
[0053]
(Second embodiment)
Next, a second embodiment of the present invention will be described based on FIG. 5 or FIG. In addition, about the structure similar to 1st embodiment, the same code | symbol is attached | subjected and the description is abbreviate | omitted, FIG. 5 respond | corresponds to E part shown in FIG. 3, FIG. 6 shows in FIG. It is sectional drawing of a boundary part.
[0054]
In the present embodiment, the configuration shown in FIG. 3 is employed in order to further increase the effect of preventing the developer aggregation from the first embodiment. That is, by gradually reducing the screw diameter D at the boundary between the main conveyance portion 2a and the sub conveyance portion 2b of the screw 2, the developer conveyance force at the boundary portion is gradually reduced, and the compression force is increased. Can be prevented.
[0055]
In the present embodiment, since the conveyance force at the boundary portion does not change suddenly, it is possible to maintain a high conveyance capability.
[0056]
Needless to say, a further effect can be achieved by combining the first embodiment and the second embodiment.
[0057]
Therefore, according to the present embodiment, the screws 2 and 3 including the screw blades 2 'and 3' cause the developer in the developing container 4 to face the boundary between the main transport unit 2a and the sub transport unit 2b. Since the developer conveying force is reduced according to the diameter D of the blades 2 ′ and 3 ′, the developer is not excessively compressed at the boundary portion, and the aggregation of the developer at the boundary portion is suppressed. It can be transported smoothly.
[0058]
(Third embodiment)
Next, a third embodiment of the present invention will be described with reference to FIG.
[0059]
In this embodiment, the present invention is adapted to a toner hopper device that supplies toner as powder to the developing device.
[0060]
The hopper 50 has a rotatable agitation shaft 52 and agitation dedicated 53 in a hopper container 51 (hereinafter referred to as a container 51) as a housing, and agitates the toner in the container. The agitated toner is conveyed in the X direction in the figure by a screw 54 as a main conveying means, and further conveyed in the Y direction in the figure by a screw 55 as a main conveying means. Similar to the first embodiment, the screws 54 and 55 are respectively provided with main conveying portions 54a and 55a as main conveying means, and sub conveying portions 54b and 55b whose conveying directions are opposite to those of the main conveying portion. Notch portions 54c and 55c having no conveyance force are provided at the boundary between the main conveyance unit and the sub conveyance unit.
[0061]
The toner conveyed in the X direction in the figure by the screw 54 and further conveyed in the Y direction in the figure by the screw 55 is supplied from the toner supply port 51 b of the container 51 to the supply port 4 d of the developing device 4.
[0062]
Since the hopper device needs to accurately supply a necessary amount of toner to the developing device, the clearance between the screw 55 and the inner surface of the conveying portion 51a of the container 51 should be as small as possible. Therefore, the compression received by the toner at the boundary portion The force is very high and is very effective in preventing toner from being collected at the boundary of the conveying screw.
[0063]
In the first to third embodiments, an example using a developer as a powder and an example using a toner have been shown. However, the present invention is not limited to this, and used toner is not limited to this. It is applicable also to the apparatus to be used.
[0064]
Therefore, according to the present embodiment, the screws 54 and 55 having the screw blades convey the toner in the container 51 through the notch 55c at the boundary between the main transport portions 54a and 55a and the sub transport portions 54b and 55b. Since the force is reduced, the toner is not excessively compressed at the boundary, and the toner can be smoothly conveyed while suppressing aggregation of the toner at the boundary.
[0065]
【The invention's effect】
As described above, according to the first , third, and fifth inventions of the present application, the main transport means and the sub-transport means are rotatable screw bodies including screw blades, and the main transport Since the diameter of the screw blades gradually decreases toward the connecting part between the means and the sub-conveying means, the powder is not excessively compressed at the connecting part, and the aggregation of the powder at the connecting part is suppressed smoothly. Can be conveyed.
[0067]
The second of the present application, the fourth, according to the sixth invention, the rotatable main transport means and auxiliary transport means is a screw member comprising a screw blade, a main carrier unit of the powder in the housing Since the developer conveying force is reduced by the notch of the connecting portion with the sub-conveying means, the powder is not excessively compressed at the connecting portion, and aggregation of the powder at the connecting portion is suppressed. It can be transported smoothly.
[Brief description of the drawings]
FIG. 1 is a schematic cross-sectional view showing a schematic configuration of an image forming apparatus according to a first embodiment of the present invention.
2 is a schematic cross-sectional view showing a schematic configuration of a developing device provided in the image forming apparatus of FIG.
3 is a cross-sectional view taken along the line AA of the developing device of FIG.
4 is an enlarged cross-sectional view of a portion E of the powder conveyance device provided in the developing device of FIG. 3;
FIG. 5 is a schematic configuration diagram showing a part of a powder conveyance device according to a second embodiment of the present invention. FIG. 6 is a cross-sectional view of the powder conveyance device of FIG.
FIG. 7 is a schematic cross-sectional view showing a schematic configuration of a toner hopper device as an example of a powder conveying device according to a third embodiment of the present invention.
FIG. 8 is a schematic cross-sectional view showing a schematic configuration of a conventional developing device.
9 is a cross-sectional view taken along the line A′-A ′ of the developing device in FIG. 8. FIG.
10 is an enlarged cross-sectional view of part E of the powder conveying device provided in the developing device of FIG.
[Explanation of symbols]
4 Developer container (housing)
2 1st screw body 2 'blade (screw blade)
2a Main transport section (main transport means)
2b Sub-transport section (sub-transport means)
2c Notch 20 Image forming device 24 Developing device 51 Container (housing)
54 Screw body 54a Main transport section (main transport means)
54b Sub-transport section (sub-transport means)
54c Notch part 55 Screw body 55a Main conveyance part (main conveyance means)
55b Sub-transport section (sub-transport means)
55c Notch

Claims (6)

A housing for storing powder, a main transport means for transporting the powder in the housing in a predetermined direction, and a sub-transport for transporting the powder in the housing in a direction opposite to the predetermined direction toward the transport end of the main transport means have a means, the main transport means and auxiliary transport means, the in and the powder conveying apparatus adapted to reduce the powder conveying force at the junction between the main conveying means and the sub-carrier means, the main transport means and the sub The conveying means is a rotatable screw body provided with screw blades, and the diameter of the screw blades gradually decreases toward the connecting portion between the main conveying means and the sub conveying means. apparatus. Main conveying means and the sub-conveying means, the powder conveying apparatus of claim 1, the connecting portion between the main transport means and auxiliary transport means and that is that there is no cut portion of the screw blade. A developing device for visualizing the latent image by applying a developer as a powder contained in a developing container as a housing to the latent image, comprising the powder conveying device according to claim 1. Developing device. The developing device according to claim 3 , wherein the main conveyance unit and the sub conveyance unit are notched portions having no screw blades at a connection portion between the main conveyance unit and the sub conveyance unit. An image forming apparatus for recording an image formed by a series of image forming processes on a recording medium, comprising the powder conveying device according to claim 1 or the developing device according to claim 3. Image forming apparatus. 6. The image forming apparatus according to claim 5 , wherein in the main transport unit and the sub transport unit, a connection portion between the main transport unit and the sub transport unit is a notch without a screw blade.

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