JP2008070402A - Developing device and image forming apparatus with the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a developing device capable of restraining deterioration in developer due to the heat. <P>SOLUTION: A developing part 8 provided in a printer 1 has a function for supplying toner to a photoreceptor drum 31 for transferring a toner image to paper, and is equipped with: a developing housing 81 for storing the toner; mixing rollers 83 and 84 for stirring the toner in the developing housing 81; a magnet roller 85 carrying the toner on its circumferential surface and supplying it to the photoreceptor drum 31; and a developing blade 86 disposed to leave predetermined space between the circumferential surface of the magnet roller 85 and the developing blade 86 and adjusting the amount of the toner carried on the magnet roller 85. The developing housing 81 contains material composed of heat conductive resin. The developing part 8 is further equipped with a duct D for cooling the developing housing 81. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a developing device provided in an image forming apparatus such as a copying machine, a printer, a facsimile, or a composite machine using an electrophotographic system.

  2. Description of the Related Art Conventionally, an image forming apparatus is configured to perform an image forming process on a sheet supplied from a sheet feeding unit, and the image forming unit is a photosensitive for transferring an image (toner image) onto the sheet. And a developing device for supplying a developer (toner) to the photosensitive drum. The developing device is provided with a developing housing that stores a developer to be supplied to the photosensitive drum.

The developing housing of this developing device is generally made of a resin such as ABS (acrylonitrile, butadiene, styrene), and some wide copying machines are made of aluminum (for example, Patent Document 1). ).
JP 63-184774 A

  However, in the conventional ABS resin development housing, the frictional heat generated by the developer agitation is difficult to be transmitted from the developer to the development housing, so that the temperature of the developer rises and promotes the deterioration of the developer. was there.

  In addition, in an aluminum development housing such as Patent Document 1, heat is easily transmitted from the developer to the development housing, but since the heat dissipation of aluminum is low, the heat transmitted to the development housing is transferred from the development housing to the outside. It is difficult to radiate, and the developing housing and the developer are in a heat saturation state relatively early. As a result, the temperature of the developer and the developing housing rises, and there is a problem that the deterioration of the developer is promoted.

  SUMMARY An advantage of some aspects of the invention is to provide a developing device capable of suppressing deterioration of a developer due to heat and an image forming apparatus including the developing device. .

  In order to achieve the above object, a developing device according to claim 1 of the present invention is a developing device for supplying a developer to a photosensitive drum for transferring an image onto a sheet, and developing the developer. The developing housing includes a material made of a heat conductive resin.

  In the developing device according to the first aspect, as described above, the developing housing for containing the developer is made of the heat conductive resin, so that both the heat conductivity and the heat dissipation of the heat conductive resin are relatively low. For example, the heat generated when the developer is stirred by the mixing roller or when the developer passes between the magnet roller and the developing blade can be quickly transferred (transmitted) from the developer to the developing housing. In addition, since the heat transmitted to the developing housing can be easily radiated from the developing housing to the outside, it is possible to suppress an increase in the temperature of the developer. Thereby, deterioration of the developer due to heat can be suppressed. The heat conductive resin is a resin having a thermal conductivity of about 10 to 100 times that of a general plastic. For example, [Engineering plastic material (Sumicon (registered trademark) FM) manufactured by Sumitomo Bakelite Co., Ltd.] Is mentioned.

  The developing device according to claim 1, wherein the developing device further includes a cooling means for cooling the developing housing (claim 2). Thus, by cooling the developing housing by the cooling means, the heat transferred from the developer to the developing housing can be forcibly radiated from the developing housing to the outside by the cooling means, so that the developer and the developing housing are heated. It becomes difficult to become saturated, and a large amount of heat can be transferred from the developer to the developing housing one after another. Thereby, it can suppress more effectively that the temperature of a developing agent rises.

  3. The developing device according to claim 2, wherein the cooling means is preferably provided in the developing housing and a fan for generating an air current, and the air current generated by driving the fan is provided along the outer surface of the developing housing. And a guide to be generated (Claim 3). As described above, the airflow generated by driving the fan is generated along the outer surface of the developing housing by the guide, so that the atmosphere near the outer surface of the developing housing can be easily moved, so that the developing housing can be easily cooled by the air cooling method. can do.

  In the developing device according to claim 3, it is preferable that the guide is formed integrally with the developing housing (claim 4). With this configuration, the area of the developing housing that is exposed to the airflow generated by the fan can be increased as compared with the case where a guide separate from the developing housing is attached to the developing housing. Radiation efficiency can be improved. Thereby, the cooling efficiency of the developing housing by the cooling means can be improved.

  3. The developing device according to claim 2, wherein the cooling unit preferably includes a tube member disposed in close contact with an outer surface of the developing housing, and a cooling medium flows in the tube member. (Claim 5). As described above, since the cooling medium flows through the inside of the tube member arranged on the outer surface of the developing housing, the heat of the developing housing can be transferred to the cooling medium via the tube member, so that the development can be easily performed. The housing can be cooled. At this time, when cooling water is used as the cooling medium, the developing housing can be easily cooled by the water cooling method.

  According to a sixth aspect of the present invention, an image forming apparatus includes an image forming unit that performs an image forming process on a sheet fed from a paper feeding unit, and the image forming unit transfers a photoconductor drum to the sheet. And a developing device according to any one of claims 1 to 5, wherein a developer is supplied to the photosensitive drum.

  According to the developing device and the image forming apparatus of the present invention, since the developing housing made of the heat conductive resin having relatively high thermal conductivity and heat dissipation is used, the heat generated in the developer is quickly developed from the developer. It can be moved (transmitted) to the housing, and heat transmitted to the developing housing can be easily radiated from the developing housing to the outside. Thereby, since it can suppress that the temperature of a developer rises, deterioration by the heat | fever of a developer can be suppressed.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
(First embodiment)
FIG. 1 is a cross-sectional view showing the overall configuration of a printer including a developing unit according to the first embodiment of the present invention, and FIGS. 2 to 5 show the configuration around the developing unit of the printer shown in FIG. FIG. First, the overall configuration of the printer 1 according to the first embodiment of the present invention will be described with reference to FIG. In this embodiment, an example in which the image forming apparatus of the present invention is applied to the printer 1 will be described.

  As shown in FIG. 1, the printer 1 includes a box-shaped housing 1a, and transmits paper from a terminal (not shown) while transporting paper along a transport path L provided in the housing 1a. An image is formed on the paper based on the image data thus obtained. The conveyance path L includes a horizontal portion L1 extending substantially horizontally from the front to the rear of the printer 1 (from right to left in FIG. 1), and a vertical portion L2 rising substantially vertically from the rear end portion of the horizontal portion L1. It is configured to be substantially L-shaped when viewed from the side.

  The printer 1 stores a sheet and supplies the sheet to the image forming unit 3 described below, an image forming unit 3 that forms an image on the sheet supplied from the sheet feeding unit 2, and image formation And a fixing unit 4 for fixing the toner image transferred to the sheet by the unit 3 to the sheet.

  The paper feeding unit 2 includes a paper feeding cassette 21 that is attached to the paper feeding unit 2 so as to be able to be drawn forward and is disposed below the horizontal part L1 of the transport path L in the mounted state. The paper feeding unit 2 takes out the paper in the paper feeding cassette 21 one by one by the pickup roller 22, and sends the paper to the horizontal portion L1 of the transport path L by the paper feeding rollers 23, 24, 25 and 26. The image forming apparatus 3 is configured to supply the image forming unit 3 with a predetermined timing after temporarily waiting by the registration roller 27.

  The paper feed unit 2 has a manual feed tray 28 attached to the front surface of the housing 1a. The paper placed on the manual feed tray 28 is taken out by a pickup roller 29, and the paper is taken out by the paper feed roller 24 and 26, it is possible to feed one sheet at a time to the horizontal portion L1 of the transport path L.

  The paper feed cassette 21 has a substantially rectangular parallelepiped shape with an open upper surface, and is configured to be able to stack and store paper.

  The image forming unit 3 is configured to transfer a toner image (image) to a sheet after forming a toner image (image) on the drum surface 31 a of the photosensitive drum 31. In other words, the image forming unit 3 includes a photosensitive drum 31 disposed substantially at the center in the front-rear direction of the horizontal portion L1 of the conveyance path L, a charging unit 32 disposed above the photosensitive drum 31, and a photosensitive member. The developing unit 8 disposed in front of the photosensitive drum 31, the transfer unit 34 disposed below the photosensitive drum 31, the cleaning unit 35 disposed behind the photosensitive drum 31, and the image formation. And a laser scanner unit (LSU) 36 disposed above the fixing unit 4. The developing unit 8 is an example of the “developing device” in the present invention.

  The photosensitive drum 31 rotates clockwise in FIG. 1. After the drum surface 31 a is uniformly charged by the charging unit 32, an image is formed on the drum surface 31 a by the laser scanner unit 36. An electrostatic latent image is formed by irradiating laser light based on the data from between the charging unit 32 and the developing unit 8, and toner (from the developing unit 8 to the drum surface 31a on which the electrostatic latent image is formed). A toner image is formed by supplying the developer.

  The paper supplied from the paper supply unit 2 is conveyed while being pressed against the photosensitive drum 31 by the transfer roller 34a of the transfer unit 34, thereby forming on the drum surface 31a of the photosensitive drum 31 on the surface of the paper. The transferred toner image is transferred to the fixing unit 4 after that. The toner and residual charge remaining on the drum surface 31a of the photosensitive drum 31 after transfer are removed by the cleaning unit 35. As shown in FIGS. 2 to 5, the cleaning unit 35 cleans the toner and residual charges on the circumferential surface of the photosensitive drum 31 with a cleaning case 35 b (see FIG. 5) by a cleaning blade 35 a disposed so as to be in contact with the photosensitive drum 31. ) Is scraped off inside. The cleaning case 35b is provided with a cleaning screw 35c for stirring the toner.

  The fixing unit 4 includes a heat roller 41 and a pressure roller 42, and the toner image is fixed to the paper by heat and pressure by sandwiching the paper on which the toner image is transferred by the rollers 41 and 42. It is supposed to be.

  Then, the sheet on which the toner image is fixed is discharged by a discharge roller 51 to a discharge unit 5 formed on the upper surface of the housing 1a.

  In the printer 1 of this embodiment, the switchback unit 6 is provided between the horizontal part L1 of the transport path L and the paper feed cassette 21 so that images can be formed on both sides of the paper. Further, a conveying roller 7 is disposed at an appropriate position between the fixing unit 4 and the discharge roller 51 and in the conveying path L ′ of the switchback unit 6.

  Next, the configuration of the developing unit 8 will be described with reference to FIGS.

  As described above, the developing unit 8 is provided to supply toner to the photosensitive drum 31, and includes a developing housing 81, a lid member 82, two mixing rollers 83 and 84, a magnet roller 85, And a developing blade 86.

  The developing housing 81 is formed by injection molding a material made of a heat conductive resin, and includes a housing main body 81a and three guide portions 81b, 81c, 81d. The above-mentioned heat conductive resin is a resin having a thermal conductivity of about 10 to 100 times that of a general plastic, and is aluminum (a thermal conductivity of about 200 to 260 W / m · K, an emissivity of about 0.04 to 0.06), although it has a lower thermal conductivity than aluminum, it has a high emissivity of about 0.7 to 0.9. For example, [Engineering by Sumitomo Bakelite Co., Ltd. A plastic material (Sumicon (registered trademark) FM). The thermal conductivity of such a thermal conductive resin is preferably about 2 W / m · K or more, more preferably about 5 W / m · K or more. However, if the thermal conductivity is excessively increased, the impact strength is reduced. May decrease. In the present embodiment, by using such a heat conductive resin, the developing housing 81 is capable of exhibiting the characteristics of the resin that has good thermal conductivity and easily releases heat. In addition, PPS (polyphenylene sulfide), PBT (polybutylene terephthalate), ABS, or the like can be used as the base resin of the thermal conductive resin, and a suitable material should be selected in consideration of thermal conductivity and rigidity. Can do.

  The housing body 81a is configured to accommodate toner, and as shown in FIG. 5, the first mixing chamber 81A, the second mixing chamber 81B adjacent to the first mixing chamber 81A, and the second mixing chamber. And a toner supply chamber 81C adjacent to 81B.

  Each of the three guide portions 81b, 81c, 81d extends downward from a predetermined position below the housing body 81a, and extends in the axial direction of each of the rollers 83-85 (in the direction orthogonal to the paper surface in FIG. 5). And is formed integrally with the housing body 81a. That is, in this embodiment, the three guide portions 81b, 81c, 81d are also made of the above-described heat conductive resin. The guide portion 81b extends downward from the lower end of the side wall of the housing main body 81a in front of the first mixing chamber 81A (right side in FIG. 5), and the guide portion 81c is the first mixing chamber of the housing main body 81a. The guide portion 81d extends downward from a boundary portion between the second mixing chamber 81B and the toner supply chamber 81C in the housing main body 81a. ing.

  The lid member 82 is attached to the developing housing 81 in such a manner as to abut on the lower end edges of the three guide portions 81b, 81c, 81d. By attaching the lid member 82 to the guide portions 81b, 81c, 81d of the developing housing 81 in this way, two ducts D (see FIGS. 3 and 3) extending in the axial direction of the rollers 83 to 85 below the housing body 81a. 5) is formed. The duct D is an example of the “guide” in the present invention. These ducts D have a function for generating an air flow by driving a fan (not shown) provided at a proper position of the printer 1 along the lower surface of the housing body 81a. Can be forcibly cooled. Note that the guide portion 81c may be omitted to form one duct D. Further, the lid member 82 may be formed integrally with the guide portions 81b to 81d. The fan may be a fan provided for cooling the development housing 81 exclusively, or may be a fan for cooling other heat sources such as the fixing unit 4.

  The mixing rollers 83 and 84 are provided to agitate the toner in the housing main body 81a to prevent the toner from adhering, and have a spiral-shaped agitation portion. Each of the mixing rollers 83 and 84 is rotatably supported at both ends in the axial direction on both side walls of the first mixing chamber 81A and both side walls of the second mixing chamber 81B of the housing body 81a, thereby developing the housing 81. Is attached.

  The magnet roller 85 is configured to carry toner on its peripheral surface and supply the toner to the photosensitive drum 31. The developing blade 86 is disposed at a predetermined distance from the circumferential surface of the magnet roller 85 and is provided to adjust the amount of toner carried on the magnet roller 85.

  In the developing unit 8 configured as described above, frictional heat is generated when the toner in the housing main body 81a is agitated by the mixing rollers 83 and 84 and when the toner passes between the magnet roller 85 and the developing blade 86. The temperature of the toner gradually increases. However, in this embodiment, since the developing housing 81 is formed of a heat conductive resin, heat is quickly exchanged between the toner and the developing housing 81, and the toner temperature is prevented from excessively rising.

  In the first embodiment, as described above, since the developing housing 81 that accommodates the toner is made of a heat conductive resin, both the heat conductivity and heat dissipation of the heat conductive resin are relatively high. The heat generated when the toner is agitated by the mixing rollers 83 and 84 and when the toner passes between the magnet roller 85 and the developing blade 86 can be quickly moved (transmitted) from the toner to the developing housing 81. Since the heat transmitted to the developing housing 81 can be easily radiated from the developing housing 81 to the outside, it is possible to suppress an increase in the toner temperature. As a result, toner deterioration due to heat can be suppressed.

  In the first embodiment, as described above, the developing housing 81 is cooled by the two ducts D including the guide portions 81b, 81c, 81d and the lid member 82, so that the toner moves from the toner to the developing housing 81. Since the generated heat can be forcibly radiated from the developing housing 81 to the outside through the duct D, the toner and the developing housing 81 are unlikely to be in a heat saturation state, and a large amount of heat is transferred from the toner to the developing housing 81 one after another. be able to. Thereby, it is possible to more effectively suppress the toner temperature from rising.

  In the first embodiment, as described above, the airflow generated by driving the fan is generated along the lower surface of the developing housing 81 by the duct D, so that the atmosphere near the lower surface of the developing housing 81 can be easily moved. Therefore, the developing housing 81 can be easily cooled by the air cooling method.

In the first embodiment, as described above, the guide portions 81b, 81c, 81d of the duct D are formed integrally with the housing main body 81a, so that the guide portions 81b, 81c, 81d separate from the housing main body 81a are formed. Since the area of the developing housing 81 that is exposed to the airflow generated by the fan can be increased compared to the case where the housing is attached to the housing main body 81a, the efficiency of heat radiation from the developing housing 81 to the outside can be improved. Thereby, the cooling efficiency of the developing housing 81 by the duct D can be improved.
(Second Embodiment)
FIG. 6 is a perspective view showing the configuration of the developing unit according to the second embodiment of the present invention, and FIG. 7 is a cross-sectional view of the periphery of the developing unit shown in FIG. Next, the configuration of the developing unit 108 according to the second embodiment of the present invention will be described with reference to FIGS.

  Unlike the first embodiment, the developing unit 108 of the second embodiment cools the developing housing 181 by a water cooling method. That is, the developing unit 108 includes a pipe member 182 disposed in close contact with the lower surface of the development housing 181, and cooling water (cooling medium) flows inside the pipe member 182. (See arrow in FIG. 6). A liquid other than water or a cooling gas can be used as the cooling medium.

  In the second embodiment, as described above, the cooling water flows in the pipe member 182 disposed on the outer surface of the developing housing 181, thereby transferring the heat of the developing housing 181 to the cooling water via the pipe member 182. Therefore, the developing housing 181 can be easily cooled.

  In the above-described embodiment, an example in which the present invention is applied to a printer as an example of an image forming apparatus has been described. It is.

1 is a cross-sectional view illustrating an overall configuration of a printer including a developing unit according to a first embodiment of the present invention. FIG. 2 is a perspective view illustrating a configuration around a developing unit of the printer illustrated in FIG. 1. FIG. 3 is a perspective view of the periphery of a developing unit with a different line-of-sight direction from FIG. 2. FIG. 4 is a perspective view of a state where a lid member is removed from a developing housing of the developing unit illustrated in FIG. 3. FIG. 3 is a cross-sectional view around a developing unit shown in FIG. 2. It is the perspective view which showed the structure of the image development part by 2nd Embodiment of this invention. FIG. 7 is a cross-sectional view around a developing unit shown in FIG. 6.

Explanation of symbols

1 Printer (image forming device)
2 Feeding unit 3 Image forming unit 31 Photosensitive drum 8, 108 Developing unit (developing device)
81,181 Development housing 182 Tube member (cooling means)
D Duct (guide, cooling means)

Claims (6)

A developing device for supplying a developer to a photosensitive drum for transferring an image to a sheet,
A developing housing for containing the developer;
The developing device, wherein the developing housing includes a material made of a heat conductive resin.   The developing device according to claim 1, further comprising cooling means for cooling the developing housing. The cooling means is
A fan for generating airflow,
The developing device according to claim 2, further comprising a guide that is provided in the developing housing and generates an airflow generated by driving the fan along an outer surface of the developing housing.   The developing device according to claim 3, wherein the guide is formed integrally with the developing housing. The cooling means includes a tube member disposed in close contact with the outer surface of the developing housing,
The developing device according to claim 2, wherein a cooling medium flows inside the tube member. An image forming unit that performs an image forming process on paper fed from the paper feeding unit;
The image forming unit includes:
A photosensitive drum for transferring an image to the paper;
An image forming apparatus comprising: the developing device according to claim 1, wherein a developer is supplied to the photosensitive drum.

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