WO2019088540A1

WO2019088540A1 - Developer roller with airflow generating mechanism

Info

Publication number: WO2019088540A1
Application number: PCT/KR2018/012520
Authority: WO
Inventors: Hiroaki Yoshida
Original assignee: Hp Printing Korea Co., Ltd.
Priority date: 2017-10-31
Filing date: 2018-10-23
Publication date: 2019-05-09
Also published as: JP2019082584A

Abstract

A developer roller includes a developer sleeve, a pair of flanges located at the first end and the second end of the developer sleeve, and an airflow generating mechanism. The developer sleeve has a cylindrical shape to rotate. The pair of flanges have vent holes. The airflow generating mechanism generates an airflow in the developer sleeve, through the vent holes, when the developer sleeve rotates.

Description

DEVELOPER ROLLER WITH AIRFLOW GENERATING MECHANISM

In developing devices provided with a developer roller, the temperature of developer may increase. An increase in the temperature of the developer may cause adhesion of toner to a developer layer regulating member, the generation of aggregates of toner and carrier, and the lowering of charge amount, etc., possibly leading to deterioration of image quality.

Accordingly, some developing devices provide an air blower that is external to the developer roller. The air blown by the air blower flows inside the developer roller via a through hole in the developer roller. As a result, a temperature increase of the developer roller is suppressed.

FIG. 1 is a schematic diagram showing the overall construction of an example image forming apparatus.

FIG. 2 is a vertical sectional view of an example developing device.

FIG. 3 is a schematic diagram showing the overall construction of the inside of the developing device, and flows of developer and air are indicated by arrows.

FIG. 4 is a perspective view of a first flange and a second flange.

FIG. 5 shows a table of results of a study demonstrating relationships between a number of rotations of an example developer roller and a temperature of an example blade.

In the following description, with reference to the drawings, the same reference numbers are assigned to the same components or to similar components having the same function, and overlapping description is omitted.

In some developing devices, an air blower for blowing air is provided separately (externally), and the number of parts is increased and the structure may be more complicated.

An example developer roller comprises a magnet part, a cylindrical developer sleeve for housing the magnet part, and a pair of flanges each fixed to and rotatably supported by each of the respective ends of the developer sleeve. The pair of flanges may be respectively formed with vent holes and at least one of the pair of flanges may be provided with an airflow generating mechanism that generates airflow inside the developer sleeve as the developer sleeve rotates.

Accordingly, the airflow generating mechanism may generate airflow inside the developer sleeve as the developer sleeve rotates with the flanges. For example, the airflow generating mechanism may transport air by utilizing the rotary force of the developer sleeve.

The air external to the developer sleeve may be supplied to the inside of the developer sleeve through the vent hole in one of the flanges (e.g. first flange). The air may flow through a gap between the magnet and the developer sleeve and contribute to the cooling of the developer roller. The air inside the developer sleeve may be discharged to the outside of the developer sleeve through the vent holes in the other flange (e.g. second flange).

In another example developer roller, the airflow generating mechanism may include an air supply mechanism that supplies the air outside the developer sleeve to the inside of the developer sleeve through the vent hole.

The air supply mechanism may supply, as the airflow generation mechanism, the air outside the developer sleeve to the inside of the developer sleeve through the vent hole. Airflow may thereby be generated inside the developer sleeve.

In another example developer roller, the airflow generating mechanism includes an air discharge mechanism that discharges the air inside the developer sleeve to the outside of the developer sleeve through the vent hole.

The air discharge mechanism may discharge, as the airflow generation mechanism, the air inside the developer sleeve to the outside of the developer sleeve through the vent hole. Airflow may thereby be generated inside the developer sleeve.

In another example developer roller, the airflow generating mechanism may include an impeller formed with a plurality of the vent holes.

Accordingly, as the developer sleeve rotates, the impeller may rotate as the airflow generating mechanism, thereby generating airflow that axially flows inside the developer sleeve.

Another example developer roller includes a filter disposed on an upstream side of the air supplying vent hole.

Accordingly, the filter may prevent scattered toner and the like from entering into the developer sleeve from the air supplying vent hole.

Another example developing device further includes a housing having a first housing part and a second housing part, a first transport member disposed in the first housing part to transport developer to the developer roller, and a second transport member disposed in the second housing part to transport the developer to the first housing part. The housing may be formed with a first opening for forwarding the developer transported by the second transport member to the first housing part, a second opening for forwarding the developer transported by the first transport member to the second housing part, and a developer discharge port for discharging excess developer from the first housing part. An airflow passage may be provided for sending air discharged from inside the developer sleeve via the vent hole to the developer discharge port.

Accordingly, the air discharged to the outside of the developer sleeve may pass through the airflow passage and be discharged to the outside of the housing from the developer discharge port, thereby suppressing an increase in the internal pressure of the housing.

In another example developing device, the first transport member may include a transport blade for transporting the developer from the first opening to the second opening and a counter blade disposed between the second opening and the developer discharge port for transporting the developer in a direction opposite to that of the transport blade. An outflow end of the airflow passage may be connected between the counter blade and the developer discharge port in the first housing part.

Accordingly, the air flowing out of the airflow passage may outflow between the counter blade and the developer discharge port. In the first housing part, then, airflow may also be generated between the first opening and the second opening, in response to the rotation of the developer sleeve.

If this airflow passes through a gap between the first housing part and the counter blade, the developer may entrain the airflow and flow to the developer discharge port, possibly resulting in excess discharge of the developer.

On the other hand, if the air flowing out of the airflow passage is made to outflow between the counter blade and the developer discharge port as described above, the air may act as flow to oppose the airflow that tends to flow over the counter blade. As a result, the developer between the first opening and the second opening can be suppressed from excessively flowing over the counter blade and toward the developer discharge port.

Accordingly, in some examples, a developer roller may suppress temperature increase of the developer roller, without a separate air blower.

Overall structure of image forming apparatus

A schematic construction of an example image forming apparatus 1 is described. As shown in FIG. 1, the image forming apparatus 1 is an apparatus to form color images using magenta, yellow, cyan and black colors. The image forming apparatus 1 forms an image on a paper sheet (recording medium) P.

The example image forming apparatus 1 is provided with a recording medium conveyance unit 10 for conveying the paper sheet P, developing devices 20 for developing electrostatic latent images, a transfer unit 30 for secondary transferring a toner image to the paper sheet P, photosensitive drums 40 that are electrostatic latent image carriers, on circumferential surfaces of which images are formed, and a fixing unit 50 for fixing the toner image onto the paper sheet P. A waste toner box 45 (not shown in FIG. 1) for collecting waste toner is attachably and detachably mounted to the image forming apparatus 1.

The recording medium conveyance unit 10 conveys the paper sheet P to be formed with image along a conveyance path R1. The paper sheet P is stacked and contained in a cassette K, picked up by a feed roller and conveyed. The recording medium conveyance unit 10 conveys the paper sheet P to reach a secondary transfer region R2 through the conveyance path R1 in such a timing that a toner image to be transferred to the paper sheet P arrives at the secondary transfer region R2.

The developing devices 20 are provided four in number for the respective colors. Each of the developing devices 20 is provided with a developer roller 21 for carrying toner to the photosensitive drum 40. In the developing device 20, toner and carrier are adjusted at a desired mixing ratio. In the developing device 20, the toner is uniformly distributed and a developer imparted with an optimal amount of charge is prepared. This developer is carried on the developer roller 21.

As the developer roller 21 rotates to carry the developer to a region opposing the photosensitive drum 40, toner is moved out of the developer carried on the developer roller 21 and onto an electrostatic latent image formed on the circumferential surface of the photosensitive drum 40 to develop the electrostatic latent image.

The transfer unit 30 carries the toner image formed with the developing devices 20 to the secondary transfer region R2 where the toner image is secondarily transferred to the paper sheet P. The transfer unit 30 is provided with a transfer belt 31,

support rollers

31a, 31b, 31c and 31d for supporting the transfer belt 31, primary transfer rollers 32 for holding the transfer belt 31 with the photosensitive drums 40, and a secondary transfer roller 33 for holding the transfer belt with the support roller 31d.

The transfer belt 31 is an endless belt circularly moved by the

support rollers

31a, 31b, 31c and 31d. The primary transfer rollers 32 are located to press against the photosensitive drums 40 from the inner peripheral side of the transfer belt 31. The secondary transfer roller 33 is disposed to press against the support roller 31d from the outer peripheral side of the transfer belt 31.

The photosensitive drums 40 are provided four in number for the respective colors. Each of the photosensitive drums 40 is provided along the direction of movement of the transfer belt 31. Around the circumference of the photosensitive drum 40, the developing device 20, a charge roller 41, an exposure unit 42 and a cleaning unit 43 are arranged.

The charge roller 41 is a charge means for uniformly charging the surface of the photosensitive drum 40 to a predetermined potential. The charge roller 41 is moved to follow the rotation of the photosensitive drum 40. The exposure unit 42 exposes the surface of the photosensitive drum 40 charged by the charge roller 41 in accordance with image to be formed on the paper sheet P. The potential of portions on the surface of the photosensitive drum 40 exposed by the exposure unit 42 is thereby changed to form an electrostatic latent image. The four developing devices 20 each uses the toner supplied from a toner tank N provided opposite to the developing device 20 to develop the electrostatic latent image formed on the photosensitive drum 40 and creates a toner image. The toner tanks N are respectively filled with magenta, yellow, cyan and black toners. The cleaning unit 43 collects the toner remaining on the photosensitive drum 40 after the toner image formed on the photosensitive drum 40 has been primarily transferred onto the transfer belt 31.

The fixing unit 50 adheres and fixes onto the paper sheet P the toner image that has been secondarily transferred from the transfer belt 31 to the paper sheet P. The fixing unit 50 is provided with a heater roller 51 for heating the paper sheet P and a pressure roller 52 for pressing the heater roller 51. The heater roller 51 and the pressure roller 52 are formed in cylindrical shapes, and the heater roller 51 is internally provided with a heat source such as a halogen lamp. A contact area called a fixing nip is formed between the heater roller 51 and the pressure roller 52, and the toner image is fused and fixed onto the paper sheet P while the paper sheet P is passed through the fixing nip. After the toner image has been secondarily transferred onto the paper sheet P, the toner remaining on the transfer belt 31 is collected by a belt cleaning device.

Further, the image forming apparatus 1 is provided with

discharge rollers

53 and 54 for discharging the paper sheet P on which the toner image is fixed with the fixing unit 50 to the outside of the apparatus.

Printing operation

Next, the A printing operation of the example image forming apparatus 1 will be described. When an image signal of a recording image is input to the image forming apparatus 1, the image forming apparatus 1 rotates the paper feed roller to pick up and convey a paper sheet P stacked in the cassette K. Then, the surface of the photosensitive drum 40 is uniformly charged to a predetermined potential by the charge roller 41 (charging). After that, an electrostatic latent image is formed by irradiating laser light onto the surface of the photosensitive drum 40 with the exposure unit 42 based on the received image signal (exposing).

In the developing device 20, the electrostatic latent image is developed to form a toner image (developing). Thus formed toner image is primarily transferred from the photosensitive drum 40 to the transfer belt 31 in the region at which the photosensitive drum 40 and the transfer belt 31 are opposed (transferring). The toner images formed on the four photosensitive drums 40 are successively overlaid to form a single overlaid toner image on the transfer belt 31. Then, the overlaid toner image is secondarily transferred onto the paper sheet P conveyed from the recording medium conveyance unit 10 in the secondary transfer region R2 at which the support roller 31d and the secondary transfer roller 33 are opposed.

The paper sheet P, with the secondarily transferred overlaid toner image, is conveyed to the fixing unit 50. The overlaid toner image is fused and fixed onto the paper sheet P while the paper sheet P is made to pass under heat and pressure between the heater roller 51 and the pressure roller 52 (fixing). After that, the paper sheet P is discharged to the outside of the image forming apparatus 1 by the

discharge rollers

53 and 54.

Detailed structure of developing device

A detailed structure of the example developing device 20 will be described with reference to FIG. 2 to FIG. 4.

The example developing device 20 includes a housing 60, the developer roller 21, a blade 28, a first transport member 70, and a second transport member 75.

Housing

The housing 60 is formed in the shape of a horizontally long container. The housing 60 has a partition 60a which divides vertically an internal space of the housing 60. In the housing 60, a first container chamber S1 is formed above the partition 60a and a second container chamber S2 is formed below the partition 60a. The developer roller 21 and the first transport member 70 are located in the first container chamber S1. The second transport member 75 is located in the second container chamber S2. In the housing 60, the part containing the first transport member 70 constitutes a first housing part 61 and the part containing the second transport member 75 constitutes a second housing part 62.

As shown in FIG. 3, the housing 60 is formed with a developer supply port 63, a first opening 64, a second opening 65, and a developer discharge port 66. The housing 60 is formed with the first opening 64 in the vicinity of one longitudinal end thereof (e.g. a first longitudinal end of the housing 60). The housing 60 is formed with the developer supply port 63, the second opening 65 and the developer discharge port 66 in the vicinity of the other longitudinal end (e.g. a second longitudinal end of the housing 60).

The developer supply port 63 is formed in the second housing part 62. The developer supply port 63 is an opening for sending the developer supplied from the toner tank N to the second container chamber S2. The developer includes a magnetic carrier and a non-magnetic toner.

The first opening 64 is formed in the partition 60a. The first opening 64 provides communication between the first container chamber S1 and the second container chamber S2. The first opening 64 is an opening for sending the developer transported by the second transport member 75 to the first container chamber S1.

The second opening 65 is formed in the partition 60a. The second opening 65 is arranged between the first opening 64 and the developer discharge port 66. The second opening 65 provides communication between the first container chamber S1 and the second container chamber S2. The second opening 65 is an opening for sending the developer transported by the first transport member 70 to the second container chamber S2.

The developer discharge port 66 is formed in the first housing part 61. The developer discharge port 66 is an opening for sending excess developer from the first container chamber S1 to the waste toner box 45 (schematically shown in FIG. 2).

Developer roller

The developer roller 21 is a developer carrier for supplying toner to an electrostatic latent image formed on the circumferential surface of the photosensitive drum 40. The developer roller 21 is located in an upper part of the first container chamber S1 to oppose the photosensitive drum 40. The developer roller 21 is provided with a shaft 22, a magnet part 23, a developer sleeve 24, and a pair of

flanges

80, 90. The shaft 22 and the magnet part 23 are fixed in the developer roller 21, and the developer sleeve 24 and the pair of

flanges

80, 90 are rotationally driven integrally.

The shaft 22 extends horizontally along the longitudinal direction of the housing 60. The ends of the shaft 22 are fixed/supported by the housing 60.

The magnet part 23 is fixed around the shaft 22. The magnet part 23 is a cylindrical member having a plurality of magnetic poles. In the magnet part 23, different magnetic poles are alternately arranged in a region opposing the photosensitive drum 40. The magnet part 23 exerts magnetic force on the circumferential surface of the developer sleeve 24 to carry the developer. The magnet part 23 raises bristles of a magnetic brush of the developer so that the magnetic brush comes in contact with or close to the electrostatic latent image on the photosensitive drum 40.

The developer sleeve 24 is a cylindrical member made of a non-magnetic metal. The developer sleeve 24 is formed in the shape of a cylinder. The developer sleeve 24 extends horizontally so as to be coaxial with the shaft 22 and the magnet part 23. The inner diameter of the developer sleeve 24 is slightly larger than the outer diameter of the magnet part 23. As such, a cylindrical gap 25 is formed between the developer sleeve 24 and the magnet part 23.

The pair of

flanges

80, 90 include a first flange 80 provided at one axial end (e.g. first axial end) of the developer sleeve 24 and a second flange 90 provided at the other axial end (e.g. second axial end) of the developer sleeve 24. Details of the first flange 80 and the second flange 90 will be described further below.

Blade

The blade 28 provides a layer thickness regulating member for making the developer attached to the outer circumferential surface of the developer sleeve 24 to be a layer of uniform thickness (e.g. the blade 28 is arranged to even out the developer layer on the developer sleeve 24). The blade 28 is located in an upstream side in the rotation direction of the developer sleeve 24, relative to a reference position at which the developer sleeve 24 opposes the photosensitive drum 40. The blade 28 is made of a metal material such as stainless steel.

First transport member

The first transport member 70 stirs and mixes the developer in the first container chamber S1, and transports the developer. The developer stirred and mixed by the first transport member 70 is supplied to the developer roller 21. Further, the developer transported by the first transport member 70 is returned to the first container chamber S1 via the second opening 65.

The first transport member 70 includes a first support shaft 71 and a first transport blade 72. The first support shaft 71 extends horizontally along the partition 60a. The first support shaft 71 is rotatably supported by bearings (not shown). The first transport blade 72 is formed around the outer circumferential surface of the first support shaft 71. The first transport blade 72 has a helical sloped surface arranged along the axial direction of the first support shaft 71. The first transport blade 72 transports (in the forward direction) the developer from the side of the first opening 64 to the side of the second opening 65. For example, the first container chamber S1 includes a first portion adjacent the first opening 64 and a second portion adjacent the second opening 65, and the first transport blade 72 transports the developer from the first portion to the second portion of the first container chamber S1.

A counter blade 73 is formed on the outer circumferential surface of the first support shaft 71. The counter blade 73 is provided between the second opening 65 and the developer discharge port 66. The counter blade 73 is a portion that transports the developer in a direction opposite to the forward direction of the first transport blade 72. Accordingly, the counter blade 73 prevents the developer between the first opening 64 and the second opening 65 from moving toward the developer discharge port 66. However, if the amount of the developer in the first container chamber S1 exceeds a predetermined amount, the excess developer is sent to the developer discharge port 66 over the counter blade 73. The excess developer sent to the developer discharge port 66 is collected into the waste toner box 45.

Second transport member

The second transport member 75 stirs and mixes the developer in the second container chamber S2, and transports the developer. The developer stirred and mixed by the second transport member 75 is supplied to the first container chamber S1 via the first opening 64.

The second transport member 75 includes a second support shaft 76 and a second transport blade 77. The second support shaft 76 extends horizontally along the partition 60a. The second support shaft 76 is rotatably supported by bearings (not shown). The second transport blade 77 is formed around the outer circumferential surface of the second support shaft 76. The second transport blade 77 has a helical sloped surface arranged along the axial direction of the second support shaft 76. The second transport blade 77 transports the developer from the second opening 65 toward the first opening 64.

Cooling structure of developer roller

In the example developing device 20, the temperature of the developer increases as the developer roller 21 rotates. In a region where the blade 28 and the developer sleeve 24 are arranged closely to one another, heat is accumulated as the developer makes contact with the blade 28. In particular, as the developer roller 21 is made to rotate at a higher speed in association with the increase in speed of printing operations, temperature increase of the developer is exacerbated. Such temperature increase of the developer causes the adhesion of toner to the blade 28, the generation of aggregates of toner and carrier, and the lowering of charge amount, etc., thereby leading to deterioration of image quality. Therefore, a mechanism is adopted according to which the developer roller 21 is cooled by airflow generated by the rotation of the developer roller 21. This cooling mechanism is described with reference to FIG. 2 to FIG. 4.

The first flange 80 and the second flange 90 are provided with an airflow generating mechanism to form airflow in the axial direction inside the developer roller 21. The basic structure is the same between the first flange 80 and the second flange 90.

The first flange 80 is fixed at one axial end of the developer sleeve 24. The first flange 80 is provided with a first body 81 and a first cylinder 82. The first body 81 is formed in the shape of a disc that closes an opening at the one end of the developer sleeve 24. The first cylinder 82 extends axially outwardly of the developer sleeve 24 from the axial center of the first body 81. The first cylinder 82 is formed in a cylindrical shape, and the shaft 22 is passed through the inside of the first cylinder 82. Accordingly, the first flange 80 is rotatably supported by the shaft 22. The first flange 80 is rotationally driven by a driving mechanism (not shown). Accordingly, the first flange 80, the developer sleeve 24, and the second flange 90 may be rotated integrally.

The first body 81 may be configured as an impeller having a plurality of vanes. For example, the first body 81 is formed with a plurality (14, in this example) of first vanes 83 and a plurality of first vent holes 84 each formed between two adjacent vanes 83. The plurality of first vanes 83 extend approximately radially from the first cylinder 82 to the outer periphery of the first body 81. Each of the first vanes 83 is tilted so as to send air from the outside of the developer sleeve 24 (space 29 for forming airflow, shown in FIG. 3) to the inside of the developer sleeve 24, as the first flange 80 rotates. Accordingly, the first body 81 constitutes an air supply mechanism that supplies the air outside the developer sleeve to the inside of the developer sleeve through the plurality of vent holes 84.

The second flange 90 is fixed at the other axial end (e.g. second axial end or second end) of the developer sleeve 24. The second flange 90 is provided with a second body 91 and a second cylinder 92. The second body 91 is formed in the shape of a disc that closes an opening at the other end (second end) of the developer sleeve 24. The second cylinder 92 extends axially outwardly of the developer sleeve 24 from the axial center of the second body 91. The second cylinder 92 is formed in a cylindrical shape, and the shaft 22 is passed through the inside of the second cylinder 92. Accordingly, the second flange 90 is rotatably supported by the shaft 22.

The second body 91 may be configured as an impeller having a plurality of vanes. For example, the second body 91 is formed with a plurality (14, in this example) of second vanes 93 and a plurality of second vent holes 94 each formed between two adjacent vanes 93. The plurality of second vanes 93 extend approximately radially from the second cylinder 92 to the outer periphery of the second body 91. Each of the second vanes 93 is tilted so as to form airflow in the axial direction from the inside of the developer sleeve 24 to the outside of the developer sleeve 24, as the second flange 90 rotates. Accordingly, the second body 91 constitutes an air discharge mechanism that discharges the air inside the developer sleeve 24 to the outside of the developer sleeve 24 through the plurality of vent holes 94.

As shown in FIG. 3, a filter 85 is attached to the developer roller 21. The filter 85 is fixed to a lateral end face of the first body 81 of the first flange 80. Accordingly, the filter 85 is located on an upstream side of the plurality of first vent holes 84. The filter 85 captures airborne developer (toner) outside the developer roller 21. The filter 85 can suppress the airborne developer from entering into the developer sleeve 24.

As shown in FIG. 3, the housing 60 is formed with an airflow passage 67 for sending the air discharged to the outside of the developer sleeve 24 to the developer discharge port 66. An inflow end of the airflow passage 67 opens toward the second flange 90 of the developer sleeve 64. An outflow end of the airflow passage 67 is connected to the first container chamber S1. For example, the outflow end of the airflow passage 67 is connected between the counter blade 73 and the developer discharge port 66 in the first container chamber S1.

Cooling operation

When the first flange 80 is rotationally driven by the driving mechanism, the developer sleeve 24 and the second flange 90 are integrally rotated. As the first flange 80 rotates, the air in the space 29 passes through each of the first vent holes 84 of the first vanes 83 and enters into the developer sleeve 24. Inside the developer sleeve 24, the air flows through the cylindrical gap 25. This airflow cools the developer sleeve 24.

As the second flange 90 rotates, the air inside the developer sleeve 24 passes through each of the second vent holes 94 of the second vanes 93 and flows out to the outside of the developer sleeve 24. This air flows through the airflow passage 67 and outflows between the counter blade 73 and the developer discharge port 66 in the first container chamber S1. The outflowing air basically flows toward the developer discharge port 66 and is finally sent to the waste toner box 45.

Part of the air entering into the first container chamber S1 forms an airflow A1 directed toward the counter blade 73. This airflow A1 can suppress excessive discharge of the developer into the developer discharge port 66. Namely, when an airflow A2 is generated in a space of the first container chamber S1 between the first opening 64 and the second opening 65 (hereinafter, "stirring chamber 68"), the air in the stirring chamber 68 may flow toward the developer discharge port 66 over the counter blade 73. In this case, the developer in the stirring chamber 68 may also be discharged to the developer discharge port 66 along with the airflow A2 passing over the counter blade 73.

On the other hand, part of the air flowing out of the airflow passage 67 forms the airflow A1 that opposes the airflow A2, and this enables to suppress the airflow A2 from passing over the counter blade 73. As a result, the developer in the stirring chamber 68 is suppressed from being excessively discharged through the developer discharge port 66.

Results of study

Results of a study on the effect of cooling the developer roller 21 with the example cooling mechanism are shown in FIG. 5. The results show measurements of the temperature of the blade 28 relative to the number of rotations (corresponding to printing speeds) of the developer roller 21 in Example 1, Example 2 and Comparative Example. Example 1 corresponds to the aforementioned example developer roller 21, in which a plurality (14) of first vanes 83 and a plurality of first vent holes 84 are formed in the first flange 80, and a plurality (14) of second vanes 83 and a plurality of second vent holes 84 are formed in the second flange 80. In Example 2, the structure of the first flange 80 is the same as Example 1. Meanwhile, the second flange 90 is without any second vane, and a plurality of second vent holes 94 are formed. In the Comparative Example, both the first flange 80 and the second flange 90 are not provided without any vanes or vent holes.

As shown in FIG. 5, under conditions where the number of rotations of the developer roller 21 was 367 rpm or lower, the temperature of the blade 28 did not differ between Example 1, Example 2 and Comparative Example. Under conditions where the number of rotations of the developer roller 21 was 550 rpm, the temperature of the blade 28 of Example 1 was 44 ℃, the temperature of the blade 28 of Example 2 was 46 ℃, and the temperature of the blade 28 of Comparative Example was 48 ℃. It is understood from this that the cooling effect of Example 1 and Example 2 increases as the number of rotations of developer roller 21 increases. In particular, under the condition where the number of rotations of the developer roller 21 was 733 rpm and the highest, the temperature of the blade 28 of Example 1 was 48 ℃, the temperature of the blade 28 of Example 2 was 52 ℃, and the temperature of the blade 28 of Comparative Example was 60 ℃, and Examples 1 and 2 show improved cooling effects.

In the examples described above, , airflow is generated in the developer sleeve 24 in association with the rotation of the first flange 80 and the second flange 90. With this, the developer roller 21 may be cooled by air, without having to provide an air blower or the like separately. Temperature increase of the developer roller 21 may thereby be suppressed without increasing the number of parts, and this in turn may suppress temperature increase in the developer.

For example, the first flange 80 and the second flange 90 may each be formed as the impeller, in order to generate airflow in the axial direction of the developer sleeve 24. The temperature of the blade 28 can thereby be decreased, as shown in FIG. 5.

The air discharged from the developer roller 21 is sent to the developer discharge port 66 through the airflow passage 67. Increase in the internal pressure of the housing 60 may thereby be suppressed. As part of the air flowing out of the airflow passage 67 is diverted around the counter blade 73, the developer in the stirring chamber 68 can be suppressed from excessively leaking toward the developer discharge port 66.

In the above examples, the first flange 80 and the second flange 90 are each formed with vanes. However, the second flange 90 may be adapted to be formed with the second vent holes 94, without the second vanes 93. Likewise, the second flange 90 may be adapted to be formed with the second vanes 93 and the second vent holes 94, while the first flange 80 may be adapted to be formed with the first vent holes 84, without the first vanes 83.

It is to be understood that not all aspects, advantages and features described herein may necessarily be achieved by, or included in, any one particular example. Indeed, having described and illustrated various examples herein, it should be apparent that other examples may be modified in arrangement and detail.

Claims

A developer roller comprising:

a magnet part;

a developer sleeve to house the magnet part, the developer sleeve having a first end and a second end opposite the first end; and

a pair of flanges including a first flange and a second flange, wherein

the first flange and the second flange are fixed to and rotatably supported by the first end and the second end of the developer sleeve, respectively,

the first flange and the second flange are respectively formed with vent holes, and

at least one of the first flange and the second flange is provided with an airflow generating mechanism to generate an airflow in the developer sleeve when the developer sleeve rotates.
The developer roller according to claim 1, wherein the airflow generating mechanism includes an air supply mechanism to supply air from an outside of the developer sleeve to an inside of the developer sleeve through at least one of the vent holes.
The developer roller according to claim 1, wherein the airflow generating mechanism includes an air discharge mechanism to discharge air from an inside of the developer sleeve to an outside of the developer sleeve through at least one of the vent holes.
The developer roller according to claim 1, wherein the airflow generating mechanism includes an impeller formed with a plurality of the vent holes.
The developer roller according to claim 1, further comprising a filter located on an upstream side of the vent hole.
A developing device comprising:

a developer roller comprising:

a developer sleeve to rotate, the developer sleeve having a cylindrical shape with a first end and a second end opposite the first end;

a pair of flanges including a first flange and a second flange located at the first end and the second end of the developer sleeve, respectively, wherein the first flange and the second flange have vent holes; and

an airflow generating mechanism to generate an airflow in the developer sleeve, through the vent holes, when the developer sleeve rotates;

a housing having a first housing part and a second housing part;

a first transport member located in the first housing part to transport developer to the developer roller; and

a second transport member located in the second housing part to transport the developer to the first housing part,

wherein

the housing is formed with a first opening to forward the developer transported by the second transport member to the first housing part, a second opening to forward the developer transported by the first transport member to the second housing part, and a developer discharge port to discharge excess developer from the first housing part, and

an airflow passage connected to at least one of the vent holes of the developer roller, to send air discharged from inside the developer sleeve to the developer discharge port.
The developing device of claim 6, wherein

the first housing part includes a first portion adjacent the first opening and a second portion adjacent the second opening,

the first transport member includes a transport blade to transport the developer from the first region of the first housing to the second region of the first housing, and a counter blade located between the second opening and the developer discharge port to transport the developer in a direction opposite to that of the transport blade, and

an outflow end of the airflow passage is connected between the counter blade and the developer discharge port in the first housing part.
A developer roller comprising:

a developer sleeve to rotate, the developer sleeve having a cylindrical shape with a first end and a second end opposite the first end;

a pair of flanges including a first flange and a second flange located at the first end and the second end of the developer sleeve, respectively, wherein the first flange and the second flange have vent holes; and

an airflow generating mechanism to generate an airflow in the developer sleeve, through the vent holes, when the developer sleeve rotates.
The developer roller according to claim 8, wherein the airflow generating mechanism is located at at least one among the first flange and the second flange.
The developer roller according to claim 8, wherein the airflow generating mechanism includes an air supply mechanism to supply air from an outside of the developer sleeve to an inside of the developer sleeve, through the vent holes.
The developer roller according to claim 8, wherein the airflow generating mechanism includes an air discharge mechanism to discharge air from an inside of the developer sleeve to an outside of the developer sleeve, through the vent holes.
The developer roller according to claim 8, wherein the airflow generating mechanism includes an impeller at the first flange, wherein the impeller includes a plurality of vanes that form a plurality of the vent holes between the vanes.
The developer roller according to claim 8, wherein the airflow generating mechanism includes a first impeller at the first flange to draw air into the developer sleeve, and a second impeller at the second flange to discharge the air from an inside of the developer sleeve to an outside of the developer sleeve.
The developer roller according to claim 8, further comprising a filter located upstream the vent holes, relative to a direction of the airflow that flows through the developer sleeve.