JP5772106B2 - Fixing apparatus and image forming apparatus - Google Patents

Description

  The present invention relates to a fixing device and an image forming apparatus, and more particularly to sheet-like recording media such as paper, recording paper, transfer paper, and OHP sheets discharged from the fixing device (hereinafter referred to as the present specification and claims). The present invention relates to a fixing device provided with a cooling means for cooling the sheet), and an image forming apparatus such as a copying machine, a printer, a facsimile, and a digital multi-function peripheral provided with the fixing device.

  The sheet exiting the fuser is hot and causes problems such as toner re-adhesion to the guide plate and adhesion between papers. Therefore, as a sheet cooling method, air cooling using a fan in the vicinity of the fuser sheet conveyance outlet There is a device. As described above, when wind is applied to the sheet in the vicinity of the fixing device sheet conveyance outlet, the wind hitting the sheet travels on the paper surface, and the temperature of the fixing device is lowered, so that the toner fixing property is lowered. In view of this, it has been attempted to prevent a decrease in the fixing temperature by closing the fixing device sheet conveyance outlet so as to prevent wind from flowing to the fixing device while ensuring sheet conveyance performance.

  However, with the conventional system that closes the fuser sheet conveyance outlet so that the wind does not flow to the fuser while ensuring sheet conveyance performance, condensation occurs inside the fuser and the sheet comes into contact with the sheet. In addition, the sheet quality may be deteriorated, and image defects may occur during the second side printing. This is because when the fixing device sheet conveyance outlet is closed, water vapor generated by evaporation of water contained in the sheet at the time of fixing tends to be confined inside the fixing device, resulting in dew condensation.

  Therefore, for example, in Patent Document 1 (Japanese Patent Application Laid-Open No. 2007-86509), water vapor generated in the fixing device is transported in order to reliably prevent condensation on a member such as a sheet guide plate without requiring warm-up. A heating unit that heats and fixes the toner image formed on the recording medium, and a shape and a size in which the heating unit is stored and the recording medium can pass on a conveyance path of the recording medium. There has been proposed a fixing device that includes a container having a slit and a clamping unit that is disposed so as to close the slit and clamps the entire width of the recording medium while allowing movement of the recording medium. According to the present invention, when the paper on which the toner image is transferred is conveyed, the pressure unit presses the paper against the heating roll, and the heating roll fixes the toner image on the paper by heating, and the paper is The water contained therein becomes water vapor, and the water vapor generated in this way is trapped by a nip roll disposed so as to close the paper discharge slit provided in the fixing device container, and the housing of the image forming apparatus is passed through the duct. It is discharged out of the body, and as a result, dew condensation within the housing is reliably prevented.

  In the invention described in Patent Document 1, the fixing device sheet conveyance outlet is closed by a pair of rollers so that water vapor does not leak to the outside of the fixing device, and a duct for exhausting the generated water vapor is provided inside the fixing device. However, if an exhaust duct is provided inside the fixing device to prevent condensation, the cost of the fixing device is increased and the size is also increased.

  Accordingly, the problem to be solved by the present invention is to be able to prevent a decrease in fixing temperature while performing sheet cooling with an inexpensive configuration.

In order to solve the above problems, the present invention provides a fixing device having a fixing device for fixing an image after image formation on a sheet, in a conveyance path immediately downstream of a sheet carry-out port for carrying out the sheet from the fixing device. A cooling unit that blows cooling air toward the surface of the sheet, an exhaust unit that is provided above the fixing unit and forcibly exhausts high-humidity high-temperature air in the fixing unit, and is located at the sheet carry-out port. and shielding means comprising a first conveying roller for conveying the sheet in the arrangement side of the cooling means of the sheet by abutting over the entire width of the sheet, and the shielding member sandwiching the sheet of the sheet discharge port An opening means provided on the opposite side and communicating with the inside of the fixing device, the opening means comprising a second conveyance roller having a roller that nips the first conveyance roller at one or more points. The above Space on both side surfaces of the furnace and forming an opening.

In the embodiment described later, the sheet is denoted by reference numeral 19, the fixing device is denoted by numeral 10, the sheet carry-out port is denoted by reference numeral 10f, the conveyance path is denoted by numerals 13a and 13b, the cooling air is denoted by numeral 14a, and the cooling means is the cooling device 14. In addition, high-humidity high-temperature air is denoted by reference numeral 10e, the exhaust means is the exhaust device 15, the shielding means is the shielding member 16, the opening means is the breathable member 17, the opening 17a and the opening 21, and the first transport roller is the blocking member 16, the second conveying roller is breathable member (roller) 17, corresponding, respectively Re it.

According to the present invention, high-temperature and high-humidity air rising from the inside of the fixing device can be efficiently discharged .

1 is a diagram illustrating a schematic configuration of an image forming apparatus according to an embodiment of the present invention. FIG. 2 is a diagram illustrating a state of an airflow in the vicinity of a paper discharge conveyance path from a fixing device to a paper discharge roller pair in FIG. 1. It is a principal part perspective view which shows the structure of the interruption | blocking member shown in FIG. 2, and a breathable member. It is explanatory drawing which shows the state of the airflow in the state which the sheet | seat pulled out from the ventilation area of the cooling device. It is a figure which shows other embodiment of a breathable member.

  In the present invention, the sheet cooling is performed by the sheet cooling air, and a member for blocking the sheet cooling air is provided at the sheet carry-out port of the fixing device to prevent the fixing device temperature from being lowered and the above-described blocking member is provided. It is characterized by preventing the dew condensation on the downstream side of the easy fixing device conveyance by efficiently ventilating water vapor generated from the fixing device.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a diagram illustrating a schematic configuration of an image forming apparatus according to an embodiment of the present invention. In FIG. 1, an image forming apparatus 1 includes a document reading unit 2 that reads a document, an image forming engine, an image forming unit 3 that forms an image on a sheet, and a sheet feeding unit 4 that supplies the sheet to the image forming unit. Basically, it functions as a copier.

  The document reading unit 2 feeds the document from the document table to the reading position, optically reads an image on the document by the scanner at the reading position, and converts it into image data of digital data. The image processing unit of the image forming unit 3 Send to. In the image forming unit 3, the received image data is converted into data that can be imaged, a visible image is formed on the sheet fed from the paper feeding unit 4 by the image forming engine, and heated and pressed by the fixing device 10. Then, the image is fixed on the sheet, and discharged from the discharge roller pair 11 to the discharge tray 12. In this embodiment, the image forming engine forms a monochrome or color image by electrophotography.

  A sheet feeding device 5 is disposed in the sheet feeding unit 4. The sheet feeding device 5 abuts on the uppermost surface of the sheet bundle 6 (a plurality of sheets) arranged in a stacked manner, and the uppermost part from the sheet bundle 6. Is provided with a separation unit 7 that separates and feeds the single sheet 6a to the downstream side in the transport direction. The sheet 6 a is separated by the separation unit 7 and is carried into the conveyance path 13. The sheet 6 a carried into the conveyance path 13 is conveyed upward along the conveyance path 13 by the conveyance roller pair 8, and the toner image formed by the image forming unit 3 is transferred by the transfer device 9. This toner image is fixed by the fixing device 10 as described above, and is discharged onto the paper discharge tray 12. The image forming apparatus 1 can be configured as a printer, a facsimile machine, a printing machine, or a digital multifunction machine, in addition to being configured as a copying machine.

  In this embodiment, a sheet cooling device 14 and an exhaust device 15 are provided between the fixing device 10 and the paper discharge roller pair 11. The cooling device 14 is disposed inside the curved portion 13b of the paper discharge conveyance path 13a that opens from the fixing device 10 toward the paper discharge tray 12, and the exhaust device 15 is disposed outside the curved portion 13b. The sheet conveying port 10f of the fixing device 10 is provided with a blocking member (first conveying roller) 16 that contacts the sheet at the full width of the sheet on the cooling device side 14 and closes the carry-out port 10f. Is provided with a breathable member 17 that is breathable.

FIG. 2 is a diagram showing the state of the airflow in the vicinity of the paper discharge conveyance path 13a from the fixing device 10 to the paper discharge roller pair 11 in FIG.
In the figure, the cooling device 14 is disposed on the fixing roller 10a side of the fixing device 10 inside the curved portion 13b of the paper discharge conveyance path 13a, and a blocking member 16 is disposed at the sheet carry-out port 10f of the fixing device 10 on the same side. Has been. The blocking member 16 is configured to abut against the entire width of the sheet 19 so that the cooling air 14a from the cooling device 14 does not enter the inside of the fixing device 10 and to keep the outer wall 10c of the fixing device 10 on the fixing roller 10a side airtight. ing. Specifically, airtightness is maintained by a seal member (not shown) or a member that covers the blocking member 16.

  The air permeable member 17 facing the blocking member 16 is configured so that an opening 17b is formed together with the outer wall 10d of the fixing device 10 on the pressure roller 10b side so as to maintain the air permeability of the fixing device 10. The air-permeable member 17 is composed of one or more rollers attached to the shaft 17a (second conveying roller), and nips with the blocking member 16 composed of the first conveying roller, and the sheet passes through the nip and is discharged. Paper. Further, the opening 17b is formed by a gap between adjacent breathable members (rollers) 17 as shown in FIG.

  An exhaust device 15 is provided above the fixing device 10, and efficiently discharges high-temperature and high-humidity air 10 e rising from the inside of the fixing device 10. The conveyance guides 20a and 20b are provided with openings (not shown) on the conveyance surface to ensure air permeability. Further, when the sheet 19 passes through the nip between the fixing roller 10a and the pressure roller 10b, the moisture contained in the sheet 19 changes into water vapor, but a large amount of water vapor is released from the pressure roller 10b side on the low temperature side. Therefore, in this embodiment, the air permeable member 17 is disposed on the pressure roller 10b side.

  FIG. 3 is a perspective view of main parts showing the configuration of the blocking member 16 and the air permeable member 17 shown in FIG. The blocking member 16 and the air permeable member 17 are configured as a roller pair in order to ensure the transportability of the sheet 19. As described above, the blocking member 16 is composed of a roller that contacts the entire width of the sheet 19 in order to block the sheet carry-out port 10f of the fixing device 10, and the air-permeable member 17 has one or a plurality of rollers in order to ensure air permeability. And is rotatably supported by a shaft 17a. Thus, the sheet is nipped as a pair of rollers having a blocking function and a ventilation function by the blocking member 16 and the air-permeable member 17, and the conveyance function is also provided.

FIG. 4 is an explanatory view showing the state of the airflow when the sheet 19 is removed from the air blowing area of the cooling device 14.
As shown in FIG. 2, during the conveyance of the sheet 19, the cooling air 14 a flows along the inside of the curved portion of the sheet 19 to cool the sheet 19, but if the sheet 19 passes through the air blowing area of the cooling device 14, The wind 14a passes through the conveyance guides 20b and 20c. On the other hand, the exhaust device 15 is located above the opening 17b, and the high-temperature high-humidity air 10e in the fixing device 10 is sucked and exhausted from the opening 17b by the exhaust device 15. Therefore, the cooling air 14a that has passed through the conveyance guides 20b and 20a flows into the high-temperature and high-humidity air 10e from the fixing device 10, and is sucked together by the exhaust device 15 and exhausted to the outside. Such an intake action makes it possible to discharge the high-temperature and high-humidity air 10e between sheets, particularly during continuous printing, and a high dew condensation prevention effect can be obtained even in a high-speed machine. At that time, the cooling air is continuously blown by the cooling device 14 for a predetermined time after the sheet is conveyed. Thus, it is possible to sufficiently cool to the set temperature before the start of fixing the next job.

  Further, if the wall-shaped guide member 15a for guiding the wind of the cooling device 14 to the exhaust device 15 side is provided, the exhaust device 15 can surely exhaust the air together with the high-temperature and high-humidity air 10e.

  The cooling device 14 includes a fan that forcibly sends the cooling air 14a, and the exhaust device 15 includes a fan that forcibly sucks and exhausts the high-humidity high-temperature air 10e.

  FIG. 5 is a view showing another embodiment of the breathable member. In this embodiment, the air-permeable member 17 shown in FIGS. 2 and 3 is a roller-shaped conveying member (third conveying roller) that makes contact with the full width of the sheet in the same manner as the blocking member 16 in consideration of the contact state of the sheet surface. ) 18. In this example, since the nip pressure between the blocking member 16 and the conveying member 18 is averaged over the entire sheet width, the possibility of affecting the image formed on the sheet 19 is reduced. However, since the high-temperature and high-humidity air 10e cannot be exhausted from the fixing device 10, an opening 21 is provided on the rear side with respect to the sheet 19 of the conveying member 18. That is, in the example of FIG. 5, an opening 21 that communicates with the inside of the fixing device 10 is provided between the non-breathable conveying member 18 and the outer wall 10 d of the fixing device 10. The high-humidity air 10e was forcibly sucked. Also in this case, the guide member 15a shown in FIG. 4 is provided to improve the exhaust efficiency. 5 differs from the opening 17b shown in FIG. 3 in that the opening has a uniform width over the entire width of the sheet.

  Other parts that are not particularly described are configured in the same manner as the fixing device 10 shown in FIGS. 1 and 2.

As described above, according to the present embodiment,
1) Since only the blocking member 16 and the air permeable member 17 are used, sheet cooling and a decrease in fixing temperature can be prevented with an inexpensive configuration.
2) It is possible to prevent the occurrence of dew condensation inside the fixing device, and it is possible to eliminate problems caused by the high temperature of the sheet and to secure stable fixing properties.
3) It is possible to prevent deterioration of transportability due to the occurrence of condensation, deterioration of sheet quality, and occurrence of image defects.
4) Since the blocking member 16 includes a roller that makes contact with the entire width of the sheet, a stable sheet conveyance quality can be obtained while contacting the sheet 19.
5) Since the air permeable member 17 is made of a roller supported by the shaft 17a, stable sheet conveyance quality can be obtained and air permeability can be ensured.
6) Since the cooling device 14 is operated even after a certain period of time between the sheets and after the sheet is conveyed, the high-temperature and high-humidity air 10e discharged from the fixing device 10 can be guided to the exhaust device 15 together with the cooling air 14a, thereby improving the cooling efficiency. Is possible.
7) Since the guide member 15a is provided, the high-temperature and high-humidity air discharged from the fixing device 10 can be reliably guided to the exhaust device 15 using the cooling air 14a from the cooling device 14.
There are effects such as.

  The present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the gist of the present invention, and all technical matters included in the technical idea described in the claims are included. The subject of the present invention. The above embodiment shows a preferable example, but those skilled in the art can realize various alternatives, modifications, variations, and improvements from the contents disclosed in this specification, These are included within the scope defined by the appended claims.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 10 Fixing device 10e High-humidity high temperature air 10f Sheet carry-out port 13a, 13b Conveyance path 14 Cooling device 14a Cooling air 15 Exhaust device 15a Guide member 16 Shielding member (first conveyance roller)
17 Breathable member (second transport roller)
17a, 21 Opening 17b Space on both side surfaces of roller 18 Conveying member (third conveying roller)
19 seats

JP 2007-86509 A

Claims (4)

A fixing device having a fixing device for fixing an image after image formation on a sheet,
A cooling means for blowing cooling air toward the surface of the sheet in a conveyance path immediately downstream of a sheet carry-out port for carrying out the sheet from the fixing device;
An exhaust means provided above the fixing device and forcibly exhausting high-humidity high-temperature air in the fixing device;
A shielding means comprising a first conveying roller that the located sheet outlet port, to convey the contact to the sheet over the entire width of the sheet in the arrangement side of the cooling means of said sheet,
An opening means provided on a side of the sheet carry-out port facing the shielding member across the sheet, and communicating with the inside of the fixing device;
Equipped with a,
The opening means includes a second transport roller having a roller that nips with the first transport roller at one or more points, and spaces on both side surfaces of the roller form an opening. A fixing device characterized by the above. A fixing device having a fixing device for fixing an image after image formation on a sheet ,
A cooling means for blowing cooling air toward the surface of the sheet in a conveyance path immediately downstream of a sheet carry-out port for carrying out the sheet from the fixing device;
An exhaust means provided above the fixing device and forcibly exhausting high-humidity high-temperature air in the fixing device;
A shielding means comprising a first conveying roller for conveying the sheet located in outlet port, the sheet disposed side contact over the entire width of the sheet of the cooling means of said sheet,
An opening means provided on a side of the sheet carry-out port facing the shielding member across the sheet, and communicating with the inside of the fixing device;
Have
The opening means is formed by a third conveying roller having a roller that nips across the entire width of the first conveying roller, and an outer peripheral surface of the third conveying roller and an upper surface of the fixing device at the sheet carry-out port. fixing device comprising an opening which is, <br/> things made of. A fixing device having a fixing device for fixing an image after image formation on a sheet ,
A cooling means for blowing cooling air toward the surface of the sheet in a conveyance path immediately downstream of a sheet carry-out port for carrying out the sheet from the fixing device;
An exhaust means provided above the fixing device and forcibly exhausting high-humidity high-temperature air in the fixing device;
A shielding means located at the sheet carry-out port and abutting over the entire width of the sheet on the arrangement side of the cooling means of the sheet;
An opening means provided on the side of the sheet carry-out port facing the shielding member and above the pressure roll of the fixing device, and communicates with the inside of the fixing device and discharges water vapor in the fixing device. When,
Fixing apparatus characterized by comprising a. An image forming apparatus comprising the fixing device according to claim 1 .

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