JP3983174B2 - Image forming apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an image forming apparatus including a fixing unit using a heat roller fixing method.
[0002]
[Prior art]
In an electrophotographic image forming apparatus, a heat source is incorporated in at least one roller of a roller pair forming a nip, and a sheet carrying an unfixed toner image is inserted into the nip of the roller pair heated by the heat source. Thus, a heat roller fixing method for fixing toner onto a sheet is widely used.
[0003]
In recent image forming apparatuses such as copying machines, there is a strong demand for higher image quality and higher speed. However, a certain amount of heat is required to fix the toner on the paper, and as the speed increases, the temperature around the fixing portion increases rapidly, and the paper after the toner fixing is not sufficiently cooled. The phenomenon that occurs. As a result, adverse effects due to heat are exerted on members and devices around the fixing unit. Furthermore, since the discharged paper is hot, there arises a problem that, for example, in the paper stock portion during double-sided printing, the toners of the overlapping paper are fused together. Also, when the back side of the paper once used is reused for printing, there is a problem of toner adhesion.
[0004]
In order to improve these, a cooling device including a blower is provided, and air is applied from the downstream side of the fixing unit toward the paper discharged from the fixing unit and the non-sheet passing region of the fixing unit. An image forming apparatus that cools a fixing unit and a sheet has been proposed (see Patent Document 1).
[0005]
[Patent Document 1]
JP-A-9-114286 [0006]
[Problems to be solved by the invention]
However, in the image forming apparatus described in Patent Document 1, for example, when fixing a large sized sheet after a small sized sheet, the small size non-sheet passing area to be fixed first is cooled. There arises a problem that a long time is required until the size of the paper passing area rises to a predetermined temperature. Further, when various sizes of paper are continuously fixed, the temperature control becomes very complicated, causing a problem of fixing failure.
[0007]
The present invention has been made in view of the above points. In an image forming apparatus including a fixing unit using a heat roller fixing method, the temperature of the periphery of the fixing unit is decreased, and high-temperature paper discharged from the fixing unit is discharged. An object of the present invention is to provide an image forming apparatus that can be sufficiently cooled.
[0008]
[Means for Solving the Problems]
In order to solve the above-described problems, the present invention provides a fixing unit that includes a fixing member that fixes unfixed toner on a sheet and a pressure member that forms a nip that contacts the fixing member and allows the sheet to pass therethrough. In the image forming apparatus provided in the main body, the fixing unit has a paper supply / discharge unit opening, and the fixing member and the pressure member are arranged so that an external air flow is not directly applied to both the members. A cover is provided, a heat absorbing fin is provided on the inner surface of the cover, a heat radiating fin is provided on the outer surface corresponding to the heat absorbing fin, and the fixing portion is disposed in an air flow path provided in the main body. It was.
[0009]
According to this configuration, heat generated from the fixing member is not diffused to the periphery. As a result, it is possible to prevent the adverse effects caused by the heat generated from the fixing member from reaching the periphery. In addition, by disposing the fixing unit in the air flow path, air can be applied to the entire fixing unit. As a result, it is possible to cool the entire fixing unit without directly applying air to the fixing member. Further, the cover that covers the fixing member and the pressure member has an opening in the paper supply / discharge section, and the paper after fixing comes out to the air flow path, so that the paper is sufficiently cooled by the air flowing in the air flow path.
[0015]
Further, according to this configuration, the cover can easily absorb the heat generated from the fixing member, and the heat accumulated in the cover can be easily released. As a result, it is possible to further increase the cooling efficiency of the fixing unit.
[0016]
Also, a reflection member for reflecting radiant heat from the cover is provided on the inner surface of the air flow path.
[0017]
According to this configuration, the radiant heat generated from the cover is not easily transmitted to the wall of the air flow path. As a result, it is possible to further enhance the effect of preventing adverse effects due to heat from spreading around the fixing portion.
[0018]
Further, a cooling fan is provided at one end in the air flow path.
[0019]
According to this configuration, the fixing unit can be forcibly cooled by blowing or sucking air with the cooling fan. As a result, it is possible to obtain a higher cooling effect for the fixing unit.
[0020]
Further, cooling fans are provided at both ends in the air flow path.
[0021]
According to this configuration, the fixing unit can be further forcibly cooled by blowing and sucking air by the cooling fan. As a result, the cooling efficiency of the fixing unit can be further increased.
[0022]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0023]
FIG. 1 is a partial sectional view showing an image forming apparatus according to the first embodiment of the present invention. FIG. 2 is a partial top view of the image forming apparatus shown in FIG. In the main body 2 of the image forming apparatus 1, a fixing unit 10, an air circulation unit 20 for cooling the fixing unit 10, and a paper conveyance unit 30 are provided. A discharge paper tray 3 is provided beyond the fixing unit 10 through the paper conveyance unit 30.
[0024]
The fixing unit 10 includes a fixing roller 11 that is a fixing member, a pressure roller 12 that is a pressure member, and a cover 13 that covers the fixing roller 11 and the pressure roller 12. The fixing roller 11 incorporates a heat source (not shown), and fixing is performed by inserting a sheet with unfixed toner through a nip formed by the contact between the fixing roller 11 and the pressure roller 12. As a result, in the heat roller fixing method, the periphery of the fixing unit 10 and the paper after fixing become high temperature. In addition, the cover 13 covers the entire fixing roller 11 and the pressure roller 12 except for the paper feed unit opening 14 and the paper discharge unit opening 15. A one-dot chain line in FIG. And this fixing | fixed part 10 is arrange | positioned inside the air flow path 21 mentioned later.
[0025]
The air circulation unit 20 includes an air flow path 21 and cooling fans 22 to 25. The air flow path 21 is a duct-shaped member made of metal or synthetic resin, and is provided so as to communicate between the wall on the front surface F side and the wall on the rear surface R side of the main body 2 of the image forming apparatus 1. Yes. Vent holes 26 and 27 are provided at locations surrounded by the air flow path 21 of the housing 4 on the front surface F and the back surface R of the main body 2. As described above, the fixing unit 10 is disposed in the air flow path 21. It is necessary to provide a distance between the air flow path 21 and each side surface in the longitudinal direction of the cover 13 of the fixing unit 10 so that air can sufficiently flow, and the distance is set to 5 mm. On the paper path P, a paper feed opening 28 and a paper discharge opening 29 are provided. A reflective film (not shown) for reflecting the radiant heat from the cover 13 is applied to the inner surface of the air flow path 21 by a process such as plating.
[0026]
Note that the air flow path 21 may not be directly connected to the front surface F and the back surface R of the main body 2. In addition, the air flow path 21 may be connected to the housing 4 on the front surface F and the back surface R of the main body 2 by providing a separate duct.
[0027]
Cooling fans 22 to 25 are provided on the inner surface of the housing 4 on the front surface F side and the rear surface R side in the air flow path 21. By rotating the cooling fans 22 and 23 provided on the front surface F side, air is sent into the air flow path 21 through the air holes 26, and through the air holes 27 by the cooling fans 24 and 25 provided on the back surface R side. Exhaust air.
[0028]
The paper transport unit 30 is provided immediately downstream of the air circulation unit 20 and includes a transport guide 31 and a transport roller 32. As described above, the discharge paper tray 3 is provided at the end of the paper transport unit 30.
[0029]
Thus, since the fixing roller 11 as a fixing member is covered with the cover 13, the heat generated from the fixing roller 11 is not diffused to the periphery thereof. Furthermore, since the entire fixing unit 10 is disposed in the air flow path 21, it is forcibly cooled by the cooling fans 22 to 25. At this time, since the fixing roller 11 and the pressure roller 12 are covered with the cover 13 as described above, air does not directly hit these rollers. Therefore, the fixing performance is not adversely affected.
[0030]
Further, since the sheet discharged from the fixing unit 10 passes through the gap between the cover 13 and the air flow path 21, it directly cools against the air flowing through the air flow path 21. Since this air hits from the side of the paper, it does not interfere with the conveyance. For the same reason, the unfixed toner image is not disturbed also on the paper feed opening 14 and 28 side.
[0031]
In addition, you may provide the cooling fans 22-25 only in any one of the front F side and the back R side. Further, even if the cooling fan is not provided, a cooling effect can be expected only by disposing the fixing unit 10 in the air flow path 21.
[0032]
FIG. 3 is a partial cross-sectional view showing an image forming apparatus according to the second embodiment of the present invention. In the second embodiment, in order to quickly transfer the heat generated by the fixing unit 10 to the air flowing through the air flow path 21, the heat absorption fins 16 are provided on the inner surface of the cover 13 of the fixing unit 10 and the heat radiation fins are provided on the outer surface. 17 is provided. By providing the heat absorbing fins 16, the surface area of the inner surface of the cover 13 is increased, so that the cover 13 can easily absorb the heat generated from the fixing unit 10. Moreover, since the surface area of the outer surface of the cover 13 is increased by providing the radiation fins 17, it is easy to release the heat accumulated in the cover 13. Therefore, the cooling efficiency of the fixing unit 10 can be further increased. In order to transfer heat through the cover 13 as described above, the cover 13 is preferably formed of a metal having good thermal conductivity, for example, aluminum. The heat absorbing fins 16 and the heat radiating fins 17 may be used alone.
[0033]
Although the embodiment of the present invention has been described above, various modifications can be made without departing from the spirit of the present invention.
[0034]
【The invention's effect】
According to this configuration, heat generated from the fixing member is not diffused to the periphery. As a result, it is possible to prevent the adverse effects caused by the heat generated from the fixing member from reaching the periphery. Further, by arranging the fixing unit in the air flow path, air can be applied to the entire fixing unit. As a result, it is possible to cool the entire fixing unit without directly applying air to the fixing member. Further, the cover that covers the fixing member and the pressure member has an opening in the paper supply / discharge section, and the paper after fixing comes out of the air flow path, so that the paper is sufficiently cooled by the air flowing in the air flow path.
[Brief description of the drawings]
FIG. 1 is a partial cross-sectional view showing an image forming apparatus according to a first embodiment of the present invention. FIG. 2 is a partial top view of the image forming apparatus shown in FIG. Partial sectional view showing the image forming apparatus
DESCRIPTION OF SYMBOLS 1 Image forming apparatus 2 Main body 4 Housing | casing 10 Fixing part 11 Fixing roller 12 Pressure roller 13 Cover 14, 28 Paper supply part opening 15, 29 Paper discharge part opening 16 Heat absorption fin 17 Heat radiation fin 20 Air distribution part 21 Air flow path 22 -25 Cooling fan 30 Paper transport section

Claims (4)

In an image forming apparatus provided with a fixing unit that includes a fixing member that fixes unfixed toner on a sheet and a pressure member that forms a nip that contacts the fixing member and allows the sheet to pass therethrough.
The fixing unit has a paper supply / discharge unit opening, and includes a cover that covers the fixing member and the pressure member so that an external air flow does not directly contact both members, and an inner surface of the cover is provided on the inner surface of the cover. An image forming apparatus comprising: a heat-absorbing fin, a heat-dissipating fin provided on an outer surface corresponding to the heat-absorbing fin, and the fixing unit disposed in an air flow path provided in the main body. The image forming apparatus according to claim 1, further comprising: a reflecting member that reflects radiant heat from the cover on an inner surface of the air flow path. The image forming apparatus according to claim 1, further comprising a cooling fan at one end in the air flow path. The image forming apparatus according to claim 1, further comprising a cooling fan at both ends of the air flow path.

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