JP6743469B2 - Powder transfer device, developing device, process cartridge, and image forming device - Google Patents

Description

The present invention relates to a powder carrying device, a developing device, a process cartridge, and an image forming apparatus.

In an electrophotographic image forming apparatus, a two-component developer including a magnetic carrier and a non-magnetic toner is widely used as a developer for electrostatically developing a photoconductor. The two-component developer is agitated by the transport screw in the developing device, and the non-magnetic toner is triboelectrically attached to the magnetic carrier. Both ends of the rotary shaft of the transport screw are rotatably supported by a case by bearing members, and seal members are arranged on the bearing members to prevent the developer from leaking from the developing device. In such a developing device, the seal member comes into contact with the rotating shaft to generate frictional heat, and when the amount of heat generated in the bearing member is large, the toner is melted and solidified. Since the generated frictional heat increases as the torque increases, the magnitude of the frictional heat varies depending on the mounting position of the bearing member.

In Patent Document 1, in order to suppress a temperature rise due to frictional heat between the seal member and the rotary shaft, a seal member having a different rotational load between the rotary shaft and the rotary shaft is appropriate according to the magnitude of the developer pressure applied to the seal member. Is disclosed.

However, as described in Patent Document 1, it is complicated to make the seal member have different specifications for each bearing member.
The present invention has been made in view of the above, and an object of the present invention is to suppress a temperature rise of a bearing member having a different heat generation amount depending on a mounting position on a case with a simple configuration.

To solve the above problems, a first aspect of the present invention, a case for accommodating the powder, a first bearing member provided on the casing, a second bearing member, the rotating shaft by the respective bearing member Is rotatably supported, and at least one rotary transfer means for transferring the powder while stirring the powder in the axial direction by rotating around the rotation axis in the case. The first bearing member includes a first bearing body and a first seal member that comes into contact with the peripheral surface of the rotating shaft to prevent the powder from entering the first bearing body side. The second bearing member includes a second bearing body and a second seal member that comes into contact with the peripheral surface of the rotating shaft to prevent the powder from entering the second bearing body side. And a nip force of the second seal member with respect to the rotary shaft is higher than a nip force of the first seal member with respect to the rotary shaft, and the volume of the second bearing member body is the first bearing member body. It is characterized by being larger than the volume of.

According to the present invention, it is possible to suppress the temperature rise of the bearing member, which generates a different amount of heat depending on the mounting position on the case, with a simple configuration.

FIG. 1 is a schematic diagram showing a configuration of an electrophotographic printer. FIG. 3 is a schematic view showing a process cartridge used in the printer. FIG. 3 is a schematic perspective view showing a developing device of the process cartridge. It is a schematic diagram which shows the conveyance screw in the developing device. (A), (b) is a schematic sectional drawing which shows the bearing member of the same conveyance screw. It is a figure which shows the temperature rising state of a bearing member in a graph. It is a figure explaining change of arithmetic mean roughness of a contact surface, (a) shows a sectional view of a bearing, (b) shows the state where arithmetic mean roughness of a rotating shaft was changed, and (c) shows a seal member. It is a schematic diagram which shows the state which changed the arithmetic mean roughness. It is a figure which shows the relationship of arithmetic mean roughness (Ra) and temperature rise with a graph. It is a figure which shows the position of a bearing member, (a) is sectional drawing which shows a process cartridge, (b) is a schematic plan view. It is a figure which shows the position of a bearing member, (a) is sectional drawing which shows a process cartridge, (b) is a schematic plan view.

<First Embodiment>
Hereinafter, an electrophotographic printer (hereinafter, simply referred to as a printer) will be described as an example of an embodiment of an image forming apparatus to which the present invention is applied. The image forming unit will be described with an example of a process cartridge.
FIG. 1 is a schematic diagram showing the configuration of an electrophotographic printer. First, the basic configuration of the printer will be described.
In FIGS. 1 and 2, the printer 100 has four process cartridges 6Y as image forming units for generating yellow, magenta, cyan, and black (hereinafter, referred to as Y, M, C, and K) toner images. It has 6M, 6C and 6K. These use Y, M, C, and K toners of different colors as image forming substances, but have the same configuration except for them. Further, each process cartridge 6Y, 6M, 6C, 6K is replaced when it reaches the end of its life.
First, the process cartridge will be described.

FIG. 2 is a schematic view showing a process cartridge used in the printer. Since the process cartridges 6Y, 6M, 6C, and 6K are different only in the color of the toner used, they will be described below as the process cartridge 6. The process cartridge 6 develops the photoconductors 1Y, 1M, 1C, and 1K (referred to as the photoconductor 1 when the color is not limited) with toner of each color. In addition, the primary transfer bias rollers 9Y, 9M, 9C, and 9K in the drawing are denoted by reference numeral 9 without any subscript.
As shown in FIG. 2, the process cartridge 6 includes a drum-shaped photoreceptor 1 (image carrier), a drum cleaning device 2, a charge eliminating device, a charging device 4, a developing device 5, and the like. The process cartridge 6 can be attached to and detached from the main body of the printer 100, and consumable parts housed in the process cartridge 6 can be replaced at once.

The charging device 4 uniformly charges the surface of the photoconductor 1 that rotates clockwise in the drawing by a driving unit (not shown). The uniformly charged surface of the photoconductor 1 is exposed and scanned by the laser beam L and carries an electrostatic latent image for each color. The electrostatic latent image of each color is developed into each color toner image by the developing device 5 using each color toner.
Then, the toner images of the respective colors are intermediately transferred onto the intermediate transfer belt 8. The drum cleaning device 2 removes the toner remaining on the surface of the photoconductor 1 after the intermediate transfer process. Further, the charge eliminating device eliminates the residual electric charge of the photoconductor 1 after cleaning. By this charge removal, the surface of the photoconductor 1 is initialized and prepared for the next image formation.

In the above-described FIG. 1, the exposure device 7 is arranged below the process cartridges 6Y, 6M, 6C and 6K in the figure. The exposure device 7, which is a latent image forming means, irradiates the respective photoconductors of the process cartridges 6Y, 6M, 6C, and 6K with the laser light L emitted based on the image information to expose the photoconductors.
By this exposure, electrostatic latent images for Y, M, C, and K are formed on the photoconductors 1Y, 1M, 1C, and 1K, respectively. The exposure device 7 irradiates the photosensitive member with a laser beam (L) emitted from a light source through a plurality of optical lenses and mirrors while scanning with a polygon mirror rotated by a motor.

At the lower side of the exposure device 7 in the drawing, a sheet feeding unit having a transfer sheet storage cassette 26, a sheet feed roller 27 incorporated therein, a registration roller pair 28, and the like is arranged.
The transfer paper storage cassette 26 stores a plurality of transfer papers P, which are recording media, in an overlapping manner, and a paper feed roller 27 is in contact with the uppermost transfer paper P.
When the sheet feeding roller 27 is rotated counterclockwise in the figure by a driving unit (not shown), the uppermost transfer sheet P is fed between the registration roller pair 28. The pair of rotationally driven registration rollers 28, once the transfer sheet P fed from the transfer sheet storage cassette 26 is sandwiched, the rotation thereof is once stopped. Then, the transfer sheet P is conveyed toward a secondary transfer nip described later at an appropriate timing.
In the sheet feeding unit having such a configuration, the sheet feeding roller 27 and the registration roller pair 28, which is a timing roller pair, constitute a conveying unit. This conveying means conveys the transfer sheet P from the transfer sheet accommodating cassette 26, which is a means for accommodating the transfer sheet P, to a secondary transfer nip described later.

Above the process cartridges 6Y, 6M, 6C, and 6K in the drawing, an intermediate transfer unit 15 is arranged which moves the intermediate transfer belt 8 as an intermediate transfer member while stretching it. The intermediate transfer unit 15 includes an intermediate transfer belt 8, four primary transfer bias rollers 9Y, 9M, 9C and 9K, and a cleaning device 10.
The intermediate transfer unit 15 also includes a secondary transfer backup roller 12, a cleaning backup roller 13, and a tension roller 14. The intermediate transfer belt 8 is endlessly moved counterclockwise in the drawing while being stretched around these three rollers. At least one of the secondary transfer backup roller 12, the cleaning backup roller 13, and the tension roller 14 is a drive roller that moves the intermediate transfer belt 8 endlessly.

By interposing the intermediate transfer belt 8 between the primary transfer bias rollers 9Y, 9M, 9C, and 9K and the photosensitive members 1Y, 1M, 1C, and 1K, the primary transfer bias rollers 9Y, 1M, 1C, and 1K are set to 1 Form the next transfer nip.
These primary transfer bias rollers 9Y, 9M, 9C, 9K apply a transfer bias having a polarity (for example, plus) opposite to that of the toner to the back surface (the inner peripheral surface of the loop) of the intermediate transfer belt 8. All the rollers (the secondary transfer backup roller 12, the cleaning backup roller 13, and the tension roller 14) except the primary transfer bias rollers 9Y, 9M, 9C, and 9K are electrically grounded.
The intermediate transfer belt 8 sequentially moves through the primary transfer nips for Y, M, C, and K while moving endlessly. When the intermediate transfer belt 8 passes through the respective primary transfer nips, the Y, M, C, and K toner images on the photoconductors 1Y, 1M, 1C, and 1K are sequentially primary-transferred and superposed. As a result, a four-color superimposed toner image (hereinafter referred to as a four-color toner image) is formed on the intermediate transfer belt 8.

The secondary transfer backup roller 12 described above sandwiches the intermediate transfer belt 8 with the secondary transfer roller 19 and forms a secondary transfer nip. The transfer paper P is sandwiched between the intermediate transfer belt 8 and the secondary transfer roller 19 in the secondary transfer nip, and is transported to the downstream side in the transport direction (the direction opposite to the registration roller pair 28). In the secondary transfer nip, the transfer paper P and the intermediate transfer belt 8 are moving in the same direction and at the same speed, and the four-color toner image formed on the intermediate transfer belt 8 is transferred in the secondary transfer nip. Transcribed to P.
The four-color toner image transferred to the transfer paper P is fixed on the transfer paper P by heat and pressure when passing between the rollers of the fixing device 20 arranged on the downstream side in the transport direction of the secondary transfer nip. ..
After that, the transfer paper P is ejected to the outside of the printer through the space between the pair of paper ejection rollers 29. A stack portion 30 is formed on the upper surface of the printer body, and the transfer papers P ejected outside the machine by the paper ejection roller pair 29 are sequentially stacked on the stack portion 30. A bottle storage container 31 is provided below the stack unit 30 to store toner bottles 32Y, 32M, 32C and 32K of the respective colors.
Note that the transfer residual toner that has not been transferred to the transfer paper P adheres to the intermediate transfer belt 8 that has passed through the secondary transfer nip. The transfer residual toner is cleaned by the cleaning device 10.

Next, the configuration of the developing devices 5Y, 4M, 4C and 5K in the process cartridges 6Y, 6M, 6C and 6K will be described with reference to FIG. In the following description, the suffixes Y, M, C and K will be omitted.
The developing device 5 is means for developing the electrostatic latent image carried by the photoconductor 1 by supplying a developer to the photoconductor 1. The developing device 5 includes a magnetic field generating means inside, and a developing roller 51 as a developer carrying member that carries and conveys a two-component developer containing magnetic particles and toner on its surface, and a developing roller 51 carried on the developing roller 51. And a doctor blade 52 as a developer regulating member that regulates the layer thickness of the transported developer.
The developing roller 51 is housed in the developing roller housing chamber 53. The developer is stored in the developer storage chamber 54. In the developer accommodating chamber 54, two first conveying screws 55 and a second conveying screw 56 (rotary conveying means) for stirring and conveying the toner, and the toner in the set toner bottle 32 are taken into the developer accommodating chamber 54. For supplying toner, a partition wall 59 as a partition member for partitioning the developer storage chamber 54 into the first developer storage chamber 54a and the second developer storage chamber 54b, and the first developer storage chamber 54a. And the communication ports A and B (see FIG. 3) arranged between the second developer accommodating chamber 54b.
The first transport screw 55 and the second transport screw 56 are arranged in parallel in a lower case 76 that forms the inner wall of the developer accommodating chamber 54. Further, the communication ports A and B are arranged at positions corresponding to both axial end portions of the first transport screw 55 and the second transport screw 56, and the first developer storage chamber 54a and the second developer storage chamber 54b. It connects between both axial ends.

Above the toner supply port 58, a shutter 71 for closing the toner supply port 58 and a toner supply port case 72 that holds the shutter 71 and covers the toner supply port 58 are provided.
Here, reference numeral 60 is a density detection sensor for detecting the toner density of the developer. When the density detection sensor 60 detects that the toner density in the developer storage chamber 54 (second developer storage chamber 54b) is insufficient, the drive motor 41 is rotated by a replenishment signal from the control unit 57. The drive motor 41 rotates the toner bottle 32 (any one of the toner bottles 32Y, 32M, 32C, and 32K (FIG. 1)) that stores the toner of the color corresponding to the developing device 5 to rotate the toner into the developer storage chamber 54. Is replenished.
Further, the entire developing device 5 is composed of an upper case 75 including an inner wall of the developing roller accommodating chamber 53 forming a developing housing and a lower case 76 including an inner wall of the developer accommodating chamber 54. The upper case 75 and the lower case 76 constitute a case that contains the developer as powder.

FIG. 3 is a perspective view showing an example of the configuration of the developing device. FIG. 4 is a schematic view showing a carrying screw in the developing device of FIG. FIG. 4 schematically shows the flow of toner. 5A and 5B are schematic cross-sectional views showing the bearing member of the transport screw shown in FIG. The process cartridge shown in FIG. 2 is a view seen from the right side of FIG.
In FIG. 3, the upper case 75, the toner replenishing port 58, the shutter 71 for closing the toner replenishing port 58, the toner replenishing port case 72 provided so as to cover the toner replenishing port 58, and the like in FIG. 2 are omitted.
The developing device 5 is a device that develops an electrostatic latent image on one of the surfaces of the photoconductors 1Y, 1M, 1C, and 1K using a two-component developer including a magnetic carrier and toner. , A first transport screw 55 and a second transport screw 56 for stirring and transporting the replenished developer toner and the carrier, and the first transport screw 55 and the second transport screw 56 are in one direction ( It has a spiral-shaped portion for conveying in the axial direction).
Further, each axial end of the rotary shaft 55A of the first transport screw 55 is formed by a pair of bearing members 84 and 85, and each axial end of the rotary shaft 56A of the second transport screw 56 is paired by a pair of bearing members. A bearing member 83 and a bearing member 83 are rotatably supported. These bearing members 82, 83, 84, 85 are held by the lower case 76. In the first transport screw 55 and the second transport screw 56, the spiral-shaped portion rotates around the rotation axis (around the rotation axes 55A and 56A).

In such a process cartridge 6, the heat generation amount of the bearing member differs depending on the mounting position of the transport screw. The heat generation amount of the bearing member will be described with reference to FIG. As shown in FIG. 4, the toner supplied to the upstream side of the second transport screw 56 is transported to the downstream side of the second transport screw 56 while being stirred by the second transport screw 56 together with the carrier (arrow C in FIG. 4). ), and moves to the upstream side of the first transport screw 55 (the same arrow D). Further, the toner is transported by the first transport screw 55 to the downstream side of the first transport screw 55 (the arrow E), and returns to the upstream side of the second transport screw 56 (the arrow F).
In this process, in the first developer accommodating chamber 54a and the second developer accommodating chamber 54b, the pressure of the developer is larger in the bearing member on the downstream side than on the upstream side. Therefore, the bearing member 82 and the bearing member 84 receive a larger force. Further, the rotational torque is input from the bearing member 82, and the torque is transmitted in series in the order of the bearing member 83, the bearing member 84, and the bearing member 85. The amount of heat generated by the pressure of the developer and the flow of torque transmission as described above is maximum in the bearing member 82, and then decreases in the order of the bearing member 83, the bearing member 84, and the bearing member 85.

To cope with this, in the first embodiment, the volume of the bearing member is set large, that is, the heat capacity is set large according to the amount of heat generated by the contact between the seal portion (seal member) and the peripheral surface of the rotary shaft.
Here, in this example, the influence of torque is stronger and the amount of heat generation is in the order of bearing member 82>bearing member 83>bearing member 84>bearing member 85, but driving such as weakening the tightening force of the seal portion When the torque required for the above is reduced, the heat generation amounts of the bearing member 83 and the bearing member 84 may be reversed.

The size of each bearing member 82, 83, 84, 85 is changed as required. Hereinafter, a configuration for providing a difference in volume between the bearing member corresponding to the heat generation amount "small" and the bearing member corresponding to the heat generation amount "large" will be described with reference to FIG. FIG. 5A shows a bearing member 90a having a small volume corresponding to the heat generation amount "small", and FIG. 5B shows a bearing member 90b having a volume larger than the bearing member 90a corresponding to the heat generation amount "large". ..
The bearing member 90a is in contact with the bearing main body 91a that rotatably supports the rotating shaft 92 (corresponding to the rotating shafts 55A and 55B) and the peripheral surface of the rotating shaft 92 so as to slidably contact each other. A seal portion 93 (seal member) for preventing the body (developer) from entering. Further, the bearing member 90b is in contact with the bearing main body 91b that rotatably supports the rotary shaft 92, and a seal that slidably contacts the peripheral surface of the rotary shaft 92 to prevent the intrusion of powder into each bearing main body side. And a section 93.

The bearing body 91a of the bearing member 90a and the bearing body 91b of the bearing member 90b are both formed of, for example, polyacetal resin (manufactured by Polyplastics Co., Ltd.: NW-02), and the volume of the bearing body 91b is smaller than that of the bearing body 91a. It's getting bigger.
The seal portion 93 is an annular plate member formed of a material such as PTFE (polytetrafluoroethylene), and has the same specifications for the bearing member 90a and the bearing member 90b. The seal portion 93 is designed to come into contact with the rotating shaft 92, the bearing body 91a, and the bearing body 91b by giving a habit.

In the present embodiment, the bearing members 82, 83, 84 and 85 have the structure shown in FIG. 5, the seal portion 93 has a common specification, and the volumes corresponding to the bearing bodies 91a and 91b have different volumes. The heat capacity of is changing. That is, the volume (heat capacity) of the bearing main body is set to be larger as the amount of heat generated by the bearing member increases. As a result, the larger the heat generation of the bearing member, the easier the heat is to escape, and the heat generation is suppressed.
As described above, according to the present embodiment, it is possible to suppress the temperature rise of each bearing member while using a seal part having a common specification. Note that the volume of the bearing main body is limited by the size and configuration of the developing device (positions of the transport screw and the developing roller, gears for driving them, replenishing port position).
In this case, the volumes of the bearing members 82, 83, 84, 85 do not necessarily have to be increased in the order of the amount of heat generation. For example, the bearing members whose heat value is less than the melting point of the toner may have the same volume, or the bearing member having the lower heat value may have a larger volume. That is, the volume of each bearing body is sufficient to dissipate the heat generated by the contact between the seal portion and the peripheral surface of the rotary shaft so that the temperature of the bearing members 82, 83, 84, 85 does not exceed the melting point of the toner. The size may be set in accordance with the amount of heat generated by contact. For example, if the temperature of the bearing member 82 at which the amount of heat generated is maximum does not reach the melting point of the toner or higher, if the other bearing member is made to have the same size as or larger than the volume of the bearing member 82, the other bearing member is It does not exceed the melting point of the toner.

In the bearing member, it is possible to further suppress the heat generation amount by setting the thermal conductivity of the bearing main body to be larger as the heat generation amount is larger, depending on the heat generation amount. In this case, the bearing body is filled with a thermally conductive filler such as alumina, magnesium oxide, boron nitride, carbon fiber, etc., which has good thermal conductivity. This further improves heat dissipation.

Next, the experimental results on the temperature rise characteristics of the bearing member will be described. FIG. 6 is a graph showing the temperature rise state of the bearing member. In this example, two types of bearing members, bearing member I and bearing member II, were measured. The structure of each bearing member is as follows.

Bearing member I: Polyacetal resin (manufactured by Polyplastics Co., Ltd.: NW-02), volume 0.87 cm ³ , heat capacity 0.29 W/mK
Bearing member II: Polyacetal resin (manufactured by Polyplastics Co., Ltd.: NW-02) filled with a high thermal conductivity filler to improve thermal conductivity (Starlight Industry Co., Ltd.: X1411), volume 1. 1 cm ³ , heat capacity 1.1 W/mK

The bearing member under these conditions was rotated under the same conditions while holding the rotating shaft, and the temperature rising with time was measured.
As shown in FIG. 6, it was possible to suppress the temperature rise of the bearing member II having a large volume (heat capacity) and increased thermal conductivity. In the example shown in FIG. 6, the volume is increased and the thermal conductivity is increased, but the temperature rise can be suppressed by increasing only one of them.

<Second Embodiment>
In the first embodiment, the volume of the bearing member is set large, that is, the heat capacity is set large according to the amount of heat generated by the contact between the seal portion and the peripheral surface of the rotary shaft. In the second embodiment, the arithmetic mean roughness of the contact surface between the seal portion and the rotary shaft is set according to the amount of heat generated by the contact between the seal portion and the peripheral surface of the rotary shaft.
Here, when the rotating shaft of the bearing member rotates, frictional heat is generated between the rotating shaft and the sealing member.Therefore, the contact area between the sealing member and the rotating shaft is reduced, and the seal thickness and seal hardness are changed. The temperature increase can be suppressed by weakening the nip force.
In this embodiment, the contact area between the seal member and the bearing member is reduced in order to suppress the temperature rise without changing the nip force of the seal. Therefore, the arithmetic mean roughness (Ra) of the contact surface of the seal portion or the contact surface of the rotating shaft is set according to the amount of heat generated by the contact.
That is, in the present embodiment, the arithmetic mean roughness of the contact surface of the rotary shaft or the seal member is set to be larger as the amount of heat generation is larger. Thereby, the temperature rise of the bearing member can be controlled without deteriorating the sealing performance.
Here, the arithmetic average roughness (Ra) is obtained by extracting only the reference length from the roughness curve in the direction of the average line, the X axis in the direction of the average line of the extracted portion, and the Y axis in the direction of vertical magnification. When the roughness curve is represented by “y=f(x)”, the value obtained by the following formula is represented by micrometers (μm).

7A and 7B are diagrams illustrating a change in the arithmetic mean roughness of the contact surface, FIG. 7A is a sectional view of the bearing, FIG. 7B is a state in which the arithmetic mean roughness of the rotating shaft is changed, and FIG. FIG. 6 is a schematic view showing a state in which the arithmetic mean roughness of the seal member is changed.
As shown in FIG. 7A, the bearing member 110 includes a bearing body 111 that rotatably supports the rotating shaft 112 of the screw, and a seal member 113 that prevents the developer from leaking from the developing container. .. As the rotating shaft 112 rotates, frictional heat is generated between the rotating shaft 112 and the seal member 113.

In the present embodiment, as shown in FIG. 7( b ), the rotary shaft 112 is provided with a contact surface 112 a having a predetermined surface roughness Ra (roughened), and as shown in FIG. 7( c ). As described above, it is possible to provide the seal member 113 with the contact surface 113a having the surface roughness Ra of a predetermined value (roughened). Hereinafter, a case will be described in which the rotating shaft 112 shown in FIG. 7B is provided with the contact surface 112a having a surface roughness Ra of a predetermined value.

Here, the upper limit of the temperature rise around the bearing member 110 is determined from the difference (ΔT1) between the melting point of the toner and the temperature inside the actual machine, and the difference between the maximum temperature and the initial temperature (ΔT2) reached when the temperature is measured over time. ) Is ΔT1>ΔT2.

It is known that this temperature increase (ΔT2) has a correlation with the surface roughness Ra (arithmetic mean roughness) as shown in FIG. That is, the smoother the surface of the contact portion of the rotary shaft 112 with the seal member (the smaller the arithmetic average roughness (Ra)), the larger the contact area between the seal member and the rotary shaft 112, and the more easily the temperature rises.
Therefore, in order to suppress the temperature rise of the bearing member 110, it is effective to increase the value of the arithmetic mean roughness (Ra) of the contact surface 112a. However, if the arithmetic average roughness (Ra) is simply increased, the damage of the seal member 113 is accelerated and the durability of the seal member 113 is deteriorated. Therefore, it is necessary to determine the arithmetic average roughness (Ra) of the contact surface 112a in consideration of the durability of the seal member 113 as well.
Considering the durability of the bearing member 110, the smaller the arithmetic mean roughness (Ra), the better. However, considering the heat generation state from FIG. 8, the arithmetic mean roughness (Ra) is 0.8 or less. Is desirable. That is, when the arithmetic average roughness (Ra) is 0.8 or less, the temperature rise rate changes at an accelerating rate, but when the arithmetic average roughness (Ra) exceeds 0.8, the arithmetic average roughness (Ra) Since it is difficult to obtain the effect of suppressing heat generation due to the change, it is desirable that the arithmetic average roughness (Ra) be 0.8 or less.

Here, if the arithmetic mean roughness (Ra) at the contact surface 112a of the rotary shaft 112 is made the same for all the bearing members in accordance with the bearing member having the highest temperature rise, the durability will be improved even if there is a margin in temperature rise. Will be lowered. Therefore, the value of the arithmetic mean roughness (Ra) of the contact surface on the corresponding rotating shaft is changed according to the amount of heat generation. Thereby, the temperature rise of the bearing member can be efficiently suppressed. In the present embodiment, in the bearing members having the same specifications, only the arithmetic mean roughness (Ra) of the contact surface 112a of the rotating shaft 112 is changed, so that the amount of heat generated varies depending on the mounting position to the case. The temperature rise can be suppressed with a simple configuration.

In the developing device 5 shown in FIG. 4, let us consider a case where the bearing members 82, 83, 84, 85 have a large amount of heat generation in the order of, for example, bearing member 85>bearing member 82>bearing member 83≈bearing member 84. At this time, the arithmetic mean roughness (Ra) of the bearing member 85 is about 0.8, the arithmetic mean roughness (Ra) of the bearing member 82 is about 0.6, and the arithmetic mean roughness (Ra) of the bearing member 83 and the bearing 44. ) Is preferably about 0.4. In this way, if the temperature rise of the bearing member is controlled by changing the arithmetic mean roughness, the nip force of the seal member does not change and the sealing performance does not deteriorate.

The value of the arithmetic average roughness (Ra) does not necessarily have to be increased in the order of the amount of heat generation, and when it is known that the temperature does not reach the melting point temperature of the toner, the same arithmetic value is used for each bearing. The average roughness (Ra) can be used. For example, when the heat generation amount increases in the order of bearing member 85>bearing member 82>bearing member 83≈bearing member 84, the temperature rise standard is set even if the arithmetic average roughness (Ra) of bearing member 83 is set to 0.4. If it reaches, all the arithmetic mean roughness (Ra) of the bearing members 82, 83, 84 may be set to 0.4. Or, it is known that there is no difference in durability when the arithmetic average roughness (Ra) is 0.4 and 0.6, and the temperature rise is achieved when the arithmetic average roughness (Ra) is 0.4. If it is difficult, the arithmetic mean roughness (Ra) of the bearing members 82, 83, 84 may be set to 0.6.

Further, when the type of the developing device is different, the heat generation state of each bearing changes, so it is necessary to change the setting of the average arithmetic roughness (Ra) of the rotating shaft. Hereinafter, a case of a so-called lateral biaxial circulation type developing device and a so-called OD developing (one-day development) type developing device will be described.

First, the case of a horizontal biaxial circulation type developing device will be described. 9A and 9B are views showing the position of the bearing member, FIG. 9A is a sectional view showing the process cartridge, and FIG. 9B is a schematic plan view of the process cartridge. In the horizontal biaxial circulation type developing device 130, as shown in FIG. 9A, the toner replenishment side screw 132 (rotational conveyance means) and the development roller side screw 131 (rotational conveyance means) are provided in the case 130a. They are arranged in parallel so that the axes of rotation are substantially parallel. In the developing device 130, the exchange of the developer with the developing roller 133 is performed in the space portion 134 in which the developing roller side screw 131 is arranged. The developer is pumped up from the developing roller side screw 131, and the developer is also separated and collected on the developing roller side screw 131.

That is, the developing roller side screw 131 scoops up the developer and supplies it to the developing roller 133. The developing roller side screw 131 collects the developer by utilizing the repulsion of the magnetic force due to the magnetic pole arrangement inside the developing roller 133. The developing roller side screw 131 and the toner replenishment side screw 132 move the developer in the axial direction of the rotation shaft while rotating, but the toner replenishment side screw 132 is newly replenished according to the detection result of the toner concentration detection sensor. Agitate and mix the developer including the toner.

On the other hand, at a position where the developer is scooped up by the developing roller side screw 131, a layer thickness regulating member 135 having a front end facing the developing roller 133 is arranged in proximity.
The layer thickness regulating member 135 is a blade member, and its front end is positioned with a predetermined gap from the surface of the developing roller 133.

In such a developing device 130, as shown in FIG. 9B, the rotation shaft of the developing roller side screw 131 is supported by the bearing member 141F and the bearing member 141R, and the rotation shaft of the toner replenishment side screw 132 is the bearing member 142F. Are supported by the bearing member 142R. The rotation shaft of the developing roller 133 is supported by the bearing 143 and the bearing 143. The structure of each bearing member 141F, 141R, 142F, 142R is the same as that shown in FIG. 7(a).

In the developing device 130, the developer is conveyed between the developing roller side screw 131 and the toner replenishing side screw 132 as indicated by an arrow in the figure. In the developing device 130, the driving force is transmitted in the order of the bearing member 141R, the bearing member 141F, the bearing member 142F, and the bearing member 142R. The bearing member 141R is loaded by the driving force from the upstream side and also loaded by the flow of the developer. Therefore, the calorific value of the bearing member 141R is the largest.
Further, comparing the bearing member 141F with the bearing member 142F, since the transmission direction of the driving force is from 141F to the bearing member 142F, a larger driving force is applied to the bearing member 141F, but the flow of the developer depends on the bearing member 142F. Large developer pressure is applied. Considering the influences of both the driving force and the developer pressure, the bearing member 141F and the bearing member 142F have the same amount of heat generation.
Further, the bearing member 142R has the lowest temperature because it is on the upstream side of the agent flow and the downstream side of the drive transmission.
Therefore, the heat generation amount is as follows: bearing member 141R>bearing member 141F≈bearing member 142F>bearing member 142R

From the above results, the average arithmetic roughness (Ra) of the rotating shaft is set as bearing member 141R>bearing member 141F≈bearing member 142F>bearing member 142R. Specifically, the average arithmetic roughness (Ra) of the bearing member 141R is about 0.8, the average arithmetic roughness (Ra) of the bearing member 141F and the bearing member 142F is about 0.6, and the average arithmetic roughness of the bearing member 142R. (Ra) is set to about 0.4.

Next, the case of an OD type developing device will be described. FIG. 10 is a view showing the position of the bearing member, (a) is a sectional view showing the process cartridge, and (b) is a schematic plan view. As shown in FIG. 10A, in the OD type developing device 150, the developer is pumped up from the supply screw 151 (rotary conveying means) arranged on the developing roller 153 side and the other recovery screw 152 ( It is separated and collected by the rotary conveyance means).

That is, in the case 150a, the supply conveyance path 151a in which the supply screw 151 is arranged and the recovery conveyance path 152a in which the recovery screw 152 is arranged are spatially partitioned by the partition plate 154. Further, the partition plate 154 is arranged such that the end portion in the cross section orthogonal to the axial direction faces the surface of the developing roller 153 and is arranged close to the developing roller 153, so that the developer can be removed from the surface of the developing roller 153. It also functions as a separation plate that facilitates withdrawal. Due to the function of the partition plate 154 as a separation plate, the developer carried on the developing roller 153 and prevented from passing through the developing area facing the photoconductor is prevented from reaching the supply transport path 151a, and is transferred into the recovery transport path 152a. The developer can be moved toward the end smoothly.

In such a developing device 150, as shown in FIG. 10B, the rotation shaft of the supply screw 151 is supported by the bearing member 161F and the bearing member 161R, and the rotation shaft of the recovery screw 152 is the bearing member 162F and the bearing member 162R. Supported by. The rotating shaft of the developing roller 153 is supported by bearings 163 and 163. The structure of each bearing member 161F, 161R, 162F, 162R is the same as that shown in FIG. 7(a).

In the developing device 150, the developer is conveyed between the supply screw 151 and the recovery screw 152 as shown by the arrow in the figure. The driving force is transmitted in the order of the bearing member 161R, the bearing member 161F, the bearing member 162F, and the bearing member 162R. Here, the bearing member 161F and the bearing member 162F are larger than the bearings on the bearing member 161R and the bearing member 162R side, and since the gear is connected to the outside of the bearing, it is easy to radiate heat and generate the most heat. Is low. In addition, the bearing member 161R has a structure in which the rotating shaft projects outside the bearing with respect to the bearing member 162R, and thus the generated heat is easily dissipated to the outside. Therefore, the calorific value is lower than that of the bearing member 162R.
Therefore, the heat generation amount is as follows: bearing member 162R>bearing member 161R>bearing member 161F≈bearing member 162F.

From the above results, each average arithmetic roughness (Ra) is also set as bearing member 162R>bearing member 161R>bearing member 161F≈bearing member 162F. Specifically, the average arithmetic roughness (Ra) of the bearing member 162R is about 0.8, the average arithmetic roughness (Ra) of the bearing member 161R is about 0.6, and the average arithmetic roughness of the bearing member 161F and the bearing member 162F. (Ra) is set to about 0.4.

In the developing device according to each of the above-described embodiments, the contact surface that is a rough surface is worn and smoothed after long-term use, or the part on the other side that comes into contact with the contact surface that is a rough surface is rough. It may be scraped off by the contact surface that is the surface. Therefore, one or both of the rotary shaft and the seal member are coated with a material having excellent wear resistance to form a thin film. An example of the thin film is an amorphous carbon film having high abrasion resistance and low opponent attack. The characteristics such as hardness of the amorphous carbon film can be controlled by the hydrogen content and the sp2/sp3 bond ratio.
By performing the coating, the surface friction coefficient is reduced (about 0.2 to 0.3), the coated member is less likely to be scraped, and the contact partner member is less likely to be worn.

<Structure, Action, and Effect of Embodiment of the Present Invention>
<First aspect>
In this embodiment, the lower case 76 that contains the developer, the bearing members 82, 83, 84, and 85 provided in the lower case 76, and the rotary shafts are rotatably supported by the bearing members, respectively. A developing device 5 comprising: a first transport screw 55 and a second transport screw 56 that transport the developer while stirring the developer in the axial direction by rotating around the rotary shafts 55A and 56A in 76. Reference numerals 82, 83, 84 and 85 denote bearing bodies 91a and 91b that rotatably support the rotating shaft 90, and seals that come into contact with the peripheral surface of the rotating shaft 90 to prevent the intrusion of powder into the bearing body side. And the volume of the bearing bodies 91a and 91b is large enough to dissipate the heat generated by the contact between the seal part 93 and the peripheral surface of the rotating shaft 90. It is characterized by being set by.
In this aspect, the volume of the bearing main body of the bearing member, that is, the heat capacity, is set to be large enough to release the heat generated by the contact between the seal portion 93 and the peripheral surface of the rotating shaft 90. The larger the calorific value, the larger the volume of the bearing body of the bearing member may be set to secure a sufficient volume for releasing heat. According to this aspect, it is possible to suppress the temperature rise of the bearing member, which generates a different amount of heat depending on the mounting position on the case, with a simple configuration.

<Second mode>
In this aspect, the bearing bodies 91a and 91b are characterized in that the larger the amount of heat generation, the larger the thermal conductivity is set.
According to this aspect, the larger the amount of heat generation, the better the heat conductivity in the bearing body. Therefore, a large amount of heat can be transmitted more quickly in the bearing member that generates a large amount of heat. Therefore, it is possible to suppress the temperature rise of the bearing member, which generates a different amount of heat depending on the mounting position on the case, with a simple configuration.

<Third aspect>
This aspect includes two pairs of bearing members 82, 83, 84, 85 that rotatably support the respective axial end portions of the rotary shaft 90, and are arranged on the respective bearing members 82, 83, 84, 85. The seal portion 93 is characterized by having the same configuration.
According to this aspect, the same seal portion can be used for all the bearing members. As a result, it is possible to suppress an increase in cost.

<Fourth aspect>
In this aspect, the case 130a for containing the powder, the bearing members 141F, 141R, 142F, 142R provided in the case 130a, and the bearing members 141F, 141R, 142F, 142R rotatably support the rotation shaft. In addition, the developing device 130 includes a developing roller side screw 131 and a toner replenishing side screw 132 that convey the developer while stirring in the axial direction by rotating around the rotation axis in the case 130a, and each bearing member 141F, 141R, 142F, 142R include a bearing body 111 that rotatably supports the rotating shaft 112, a seal member 113 that contacts the peripheral surface of the rotating shaft 112 to prevent the developer from entering the bearing body side, The arithmetic mean roughness (Ra) of the contact surface 112a of the rotary shaft 112 with the seal member 113 is set according to the amount of heat generated by the contact.
According to this aspect, the calorific value of the bearing member can be controlled by adjusting the arithmetic mean roughness (Ra) of the contact surface, so that the temperature rise of the bearing member having a different calorific value depending on the mounting position on the case can be easily performed. It can be suppressed by the configuration.

<Fifth aspect>
This aspect is characterized in that the contact surface 112a of the rotating shaft 112 with the seal member 113 is set to have a larger arithmetic average roughness (Ra) as the amount of heat generation increases.
According to this aspect, by making the contact surface have a large arithmetic average roughness (Ra), the contact area is reduced and the amount of heat generation is reduced. Therefore, it is possible to suppress the temperature rise of the bearing member, which generates a different amount of heat depending on the mounting position on the case, with a simple configuration.

<Sixth aspect>
In this aspect, the case 130a is provided with four bearing members 141F, 141R, 142F, 142R, and between the rotary shaft 112 and the seal member 113 arranged on the bearing members 141F, 141R, 142F, 142R. The seal performances of are the same.
According to this aspect, the sealing performance of all the bearing members 141F, 141R, 142F, 142R is the same. Therefore, good sealing performance can be obtained for all the bearing members without deteriorating the sealing performance of the specific bearing member.

<Seventh mode>
In this embodiment, the first carrying screw 55 and the second carrying screw 56, which are arranged in parallel in the lower case 76 and carry the developer in mutually opposite directions, and both axial ends of the first carrying screw 55 and the second carrying screw 56. A partition wall 59 for partitioning the first transport screw 55 and the second transport screw 56 while allowing the parts to communicate with each other is provided.
According to this aspect, the developer is transported while being agitated by the first transport screw 55 and the second transport screw 56. As a result, the two-component developer composed of the magnetic carrier and the non-magnetic toner can be stirred well.

<Eighth mode>
The present embodiment is a developing device 5 for developing a latent image carried by the photoconductor 1 with toner, and the powder is a developer containing at least toner.
According to this aspect, the photoconductor 1 is developed with toner by the developing device 5. Thereby, a toner image can be formed on the photoconductor 1.

<Ninth aspect>
This embodiment is a process cartridge 6 including at least a developing device 5 and a photoconductor 1 on which a carried electrostatic latent image is developed by a developer supplied from the developing device 5.
According to this aspect, the process cartridge includes the developing device 5 and the photoconductor 1. As a result, the developing device 5 and the photoconductor 1 can be replaced at the end of their service life simply by replacing the process cartridge.

<Tenth aspect>
The present embodiment is a printer 100 including the developing device 5 or the process cartridge 6.
According to this aspect, it is possible to prevent the bearing member supporting the transport screw of the developing device from overheating. As a result, stable image formation can be realized.

5: developing device (powder conveying device), 55: first conveying screw (rotary conveying means), 55A: rotating shaft, 56: second conveying screw (rotary conveying means), 76: lower case (case), 82: Bearing member, 83: bearing member, 84: bearing member, 85: bearing member, 91a: bearing body, 91b: bearing body. 93: seal part (seal member), 110: bearing member, 111: bearing body, 112: rotating shaft, 112a: contact surface, 113: seal member, 113a: contact surface

JP, 2014-041208, A

Claims (10)

A case containing the powder,
A first bearing member provided on the casing, a second bearing member,
A rotary shaft is rotatably supported by each of the bearing members, and at least one rotary transfer unit that transfers the powder while stirring the powder in the axial direction by rotating around the rotary shaft in the case. A powder carrying device comprising:
The first bearing member includes a first bearing body, and a first seal member that comes into contact with the peripheral surface of the rotating shaft to prevent the powder from entering the first bearing body side.
The second bearing member includes a second bearing body, and a second seal member that contacts the peripheral surface of the rotating shaft to prevent the powder from entering the second bearing body side.
The nip force of the second seal member with respect to the rotary shaft is higher than the nip force of the first seal member with respect to the rotary shaft,
The powder conveying device, wherein the volume of the second bearing member body is larger than the volume of the first bearing member body . A case containing the powder,
A first bearing member having a first bearing body provided in the case, and a second bearing member having a second bearing body ,
A rotary shaft is rotatably supported by each of the bearing members, and a plurality of rotary transfer units that rotate around the rotary shaft in the case to transfer the powder in the axial direction while stirring.
A powder transfer device comprising: a drive source that applies a drive force to the plurality of rotary transfer means,
The second bearing member is arranged on the upstream side of drive transmission from the drive source with respect to the first bearing member,
The powder conveying device, wherein the volume of the second bearing member body is larger than the volume of the first bearing member body . The first bearing member and the second bearing member are composed of a seal member and a bearing body,
The thermal conductivity of the bearing body of the second bearing member is set to be higher than the thermal conductivity of the bearing body of the first bearing member. Transport device. A case containing the powder,
A first bearing member and a second bearing member provided in the case;
A rotary shaft is rotatably supported by each of the bearing members, and at least one rotary transfer unit that transfers the powder while stirring the powder in the axial direction by rotating around the rotary shaft in the case. A powder carrying device comprising:
The first bearing member includes a first seal member that contacts the peripheral surface of the rotating shaft to prevent the powder from entering the bearing body side.
The second bearing member includes a second seal member that comes into contact with the peripheral surface of the rotating shaft to prevent the powder from entering the bearing body side.
The nip force of the second seal member with respect to the rotary shaft is higher than the nip force of the first seal member with respect to the rotary shaft,
Powder transport characterized in that the arithmetic mean roughness of the contact surface between the second seal member and the rotary shaft is larger than the arithmetic mean roughness of the contact surface between the first seal member and the rotary shaft. apparatus. A case containing the powder,
A first bearing member and a second bearing member provided in the case;
A rotary shaft is rotatably supported by each of the bearing members, and a plurality of rotary transfer units that rotate around the rotary shaft in the case to transfer the powder in the axial direction while stirring.
A powder transfer device comprising: a drive source that applies a drive force to the plurality of rotary transfer means,
The second bearing member is arranged on the upstream side of drive transmission from the drive source with respect to the first bearing member,
The first bearing member includes a first seal member that contacts the peripheral surface of the rotating shaft to prevent the powder from entering the bearing body side.
The second bearing member includes a second seal member that comes into contact with the peripheral surface of the rotating shaft to prevent the powder from entering the bearing body side.
Powder transport characterized in that the arithmetic mean roughness of the contact surface between the second seal member and the rotary shaft is larger than the arithmetic mean roughness of the contact surface between the first seal member and the rotary shaft. apparatus. The first bearing member and the second bearing member are composed of a seal member and a bearing body,
The powder according to claim 4, wherein the thermal conductivity of the bearing body of the second bearing member is set to be higher than the thermal conductivity of the bearing body of the first bearing member. Transport device. The two rotary transfer means, which are arranged in parallel in the case and transfer the powder in mutually opposite directions, and the two rotary transfer means while communicating between both axial ends of the two rotary transfer means. A partitioning member for partitioning the space is provided, and the powder carrying device according to claim 1. A developing device for developing a latent image carried by an image carrier with toner,
A developing device comprising the powder conveying device according to claim 1, wherein the powder is a developer containing at least the toner. 9. A process cartridge comprising at least the developing device according to claim 8 and an image carrier on which an electrostatic latent image carried by the developer is developed by a developer supplied from the developing device. An image forming apparatus comprising the developing device according to claim 8 or the process cartridge according to claim 9.

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