JP4019581B2 - Image forming apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an image forming apparatus using an electrophotographic system such as a copying machine, a printer, a facsimile machine, or a multifunction machine of these, and more particularly to a heat countermeasure technique for the image forming apparatus.
[0002]
[Prior art]
Conventionally, in an electrophotographic image forming apparatus, a fixing device that fixes an unfixed toner image on a recording sheet by the action of heat and pressure has been widely used. Various problems occur in the image forming apparatus, such as the toner in the developing device disposed around the fixing device and the toner in the belt cleaning device are solidified by heat due to heat from the fixing device. There is a fear.
[0003]
Furthermore, as the image forming apparatus is required to be downsized, the fixing device and other component parts approach each other, and the gap in the apparatus tends to decrease. Further, improvement in productivity of the image forming apparatus is demanded, and therefore, the amount of heat generated per unit time from the fixing device tends to increase. In view of these trends, countermeasures against heat in the image forming apparatus are becoming increasingly important.
[0004]
Therefore, as a countermeasure against heat in the image forming apparatus, a technique is known in which the atmosphere in the image forming apparatus heated by the fixing device is forcibly discharged out of the image forming apparatus by a fan. An example of such a technique is described in JP-A-11-24352. As shown in FIG. 10, the technique described in this publication provides a fan around a fixing device as a heating source (apart from the recording sheet conveyance path), and further provides a duct (not shown) to warm the fixing. The atmosphere around the device is exhausted out of the device by a fan through a duct.
[0005]
[Problems to be solved by the invention]
However, with such an image forming apparatus layout, it is difficult to efficiently discharge the warmed atmosphere around the fixing apparatus to the outside of the apparatus. That is, since the fan is provided at a position relatively distant from the fixing device, the atmosphere needs to flow through the duct to the distant fan, and as a result, the exhaust efficiency decreases. Of course, it is possible to achieve sufficient exhaust performance by using a fan with a large capacity, but on the other hand, it causes adverse effects such as increased power consumption and increased noise. In particular, today, where energy saving and office environment are important, using a large capacity fan has a great disadvantage.
[0006]
The present invention has been made in view of such problems, and an object thereof is to provide an image forming apparatus having a layout excellent in exhaust efficiency.
[0007]
[Means for Solving the Problems]
That is, the present invention includes a fixing unit having an internal heat source and fixing an unfixed toner image on a recording sheet, a sheet conveyance path surface for conveying the recording sheet fixed by the fixing unit to a discharge port, and a fixing unit. In the image forming apparatus including the first and second exhaust units that exhaust the ambient atmosphere heated by the heat of the apparatus to the outside of the apparatus, the fixing unit conveys the recording sheet in the horizontal direction and fixes the recording sheet. The sheet conveyance path surface is formed upward, and the first exhaust unit exists on the normal line of the sheet conveyance path surface after the fixing above the fixing unit, and the intake air of the first exhaust unit flow or the exhaust stream, from the slit of the casing which its direction to form a sheet conveying road passes so as to be perpendicular to the sheet conveying path plane to intersect at least a part of the recording sheet conveyed Is against the exhaust, the second exhaust means is provided outside the maximum width of the recording sheet to be conveyed, but the intake flow or the exhaust flow of the second exhaust means does not intersect with the sheet conveying path plane (Claim 1). By configuring the image forming apparatus in this way, the degree of freedom in layout can be increased, and the exhaust unit can be disposed in the vicinity of the fixing device. As a result, exhaust efficiency is improved.
[0008]
A reference example of the present invention will be described below with reference to FIGS. 1 to 3 illustrate the present invention in the case where one exhaust means is provided, and FIG. 4 illustrates the present invention in the case where a plurality of exhaust means (two in the figure) are provided. 1, 2, and 4, the exhaust flow by the exhaust means intersects with the conveyance path surface, and in the aspect shown in FIG. 3, the intake flow by the exhaust means intersects with the conveyance path surface. Here, in order to discharge the warmed ambient atmosphere to the outside of the apparatus more effectively, the relationship between the direction of the intake air flow and the exhaust air flow and the conveyance path surface is substantially orthogonal, that is, the intake air flow and the exhaust air flow. Is preferably substantially coincident with the normal direction of the transport path surface.
[0009]
Next, paying attention to the position of the exhaust means , the first exhaust means exists on the normal line of the transport path surface. When the fixing unit has at least one fixing rotator, the exhaust unit may exist on a plane including a part of the rotation axis of the fixing rotator and having the rotation axis as a normal line. preferable. By configuring the image forming apparatus in this way, the exhaust unit can be disposed closer to the fixing device, and as a result, the exhaust efficiency is further improved.
[0010]
Here, the image forming apparatus includes a plurality of exhaust units, and apart from the exhaust unit that the intake flow or the exhaust flow intersects the sheet conveyance path surface, the exhaust unit that does not intersect the sheet conveyance path surface. Use together .
[0011]
In addition, the exhaust unit can be provided outside the sheet conveyance path surface. However, from the viewpoint of improving exhaust efficiency by being arranged closer to the fixing device, the exhaust unit is disposed on the sheet conveyance path surface. It is preferable that it exists in the inside. In addition, the present invention can be basically applied to any fixing unit and the layout of the conveyance path surface. However, the fixing unit conveys and fixes the recording sheet in the horizontal direction, and the conveyance path surface is positioned upward. In general, an image forming apparatus having a layout formed toward the surface tends to be difficult to take measures against heat. Therefore, when the present invention is applied to an image forming apparatus having such a layout, the effect is more remarkably exhibited.
[0012]
By the way, in the image forming apparatus according to the present invention, the exhaust flow or the intake flow is applied to the sheet conveyance path surface, but the toner image on the recording sheet conveyed on the sheet conveyance path surface is the one after fixing. No worries about disturbing the image .
[0013]
The first and second exhaust means sucks the ambient atmosphere and exhausts it outside the apparatus regardless of whether or not the recording sheet is transported to the surface of the sheet transport path.
[0017]
[Mode for Carrying Out the Invention]
FIG. 6 shows an image forming apparatus 10 including the fixing device 14 according to the present invention. As shown in FIG. 6, the image forming apparatus 10 is covered with a casing 12 and formed in a substantially box shape.
[0018]
A plurality of recording medium trays 16 (in the present embodiment, three recording medium trays 16A, 16B, and 16C are shown) are disposed below the image forming apparatus 10. Each of the recording medium trays 16A, 16B, and 16C is provided with recording media 18 having different sizes such as B5 size, B4 size, A4 size, and A3 size. A half-moon roller 20 is disposed in the vicinity of the recording medium discharge portion in the recording medium tray 16, and the recording sheets 18 are sent out one by one from the designated paper tray 16 and conveyed in a predetermined direction by a plurality of conveying roller pairs 22. Is done. In addition, when the image forming apparatus 10 instructs to form images on both sides (front and back) of the paper 28, a paper reversing unit 17 is provided for reversing the front and back of the recording sheet 18 that has finished image formation on the front side. ing.
[0019]
On one side surface of the image forming apparatus 10, a manual feed tray 24 for manually inserting the recording sheet 18 is disposed as necessary. Similar to the paper tray 16 described above, a half-moon roller 20 is disposed in the vicinity of the paper insertion portion of the manual feed tray 24 so that the recording sheets 18 can be fed one by one.
[0020]
A discharge tray 26 for discharging the recording sheet 18 on which a desired image is fixed by the fixing device 14 is provided on the upper portion of the image forming apparatus 10.
[0021]
Image data obtained by reading a document with a scanner and performing various image processing is provided above the paper tray 16 in the image forming apparatus 10 (since the image forming apparatus 10 in this embodiment is intended for color images, image processing is performed. Is converted into image data of four colors of yellow, magenta, cyan, and black), and a fixing device that fixes a desired image on the recording sheet 18. An image forming unit 28 including 14 or the like is provided.
[0022]
The optical scanning device 32 includes a light source, a rotary polygon mirror 34, an fθ lens, a cylindrical mirror, a reflection mirror 36, and the like. Laser light emitted from a light source (not shown) is deflected by the rotating polygonal mirror 34 and applied to the photoconductor 30 through an fθ lens, a cylindrical mirror, a reflection mirror 36, and the like.
[0023]
Further, around the photosensitive member 30, a charger 38, a rotary developing device 40, an intermediate transfer member 42 composed of an IBT belt, a photosensitive member cleaner 44, and a neutralizing lamp (not shown) are disposed.
[0024]
The photoconductor 30 rotates at a constant speed in the direction of arrow A shown in FIG. The charging member 38 uniformly negatively charges the photosensitive member 30. The rotary developing device 40 is supplied with toners 46Y, 46M, 46C, and 46Bk of four colors of yellow, magenta, cyan, and black. The intermediate transfer body 42 is wound around a plurality of rollers 48, and moves at a constant speed in the direction of arrow B shown in FIG. 6 as the rollers 48 rotate. The photoreceptor cleaner 44 removes toner remaining on the photoreceptor 30 without being transferred to the intermediate transfer body 42. Further, the static elimination lamp neutralizes the photoconductor 30 after the remaining toner is removed by the photoconductor cleaner 44.
[0025]
Further, an image detection sensor 51 and an intermediate transfer body cleaner 50 are disposed around the intermediate transfer body 42. The image detection sensor 51 is provided upstream of the transfer unit 52 in the rotation direction of the intermediate transfer body 42 and detects the presence or absence of a toner image formed on the intermediate transfer body 42. The intermediate transfer body cleaner 50 is provided downstream of the transfer portion 52 in the rotation direction of the intermediate transfer body 42, and after the transfer of the toner image from the intermediate transfer body 42 to the recording sheet 18 is completed, the intermediate transfer body 42. The toner remaining on the surface of the toner is removed.
[0026]
The photosensitive member 30 that rotates in the direction of arrow A is uniformly negatively charged by the charger 38, and first a black latent image of the first color is formed on the photosensitive member 30 by the laser light emitted from the optical scanning device 32. The This latent image is developed with black toner by the black developer of the rotary developer 40. The developed black toner image is transferred to the intermediate transfer body 42. The toner remaining without being transferred onto the photoconductor 30 is removed by a cleaner (not shown), and the photoconductor 30 is neutralized by a static elimination lamp.
[0027]
The photosensitive member 30 is again negatively charged uniformly by the charger 38, and the second color yellow image is formed. In this way, a total of four color toner images are sequentially transferred to the intermediate transfer body 26 from the third color magenta to the fourth color cyan. When the transfer of the four color toner images to the intermediate transfer member 42 is completed, a final toner image is formed on the surface of the intermediate transfer member 42.
[0028]
Below the intermediate transfer member 42, a transfer unit 52 that transfers the final toner image formed on the intermediate transfer member 42 to the recording sheet 18 is provided. The recording sheet 18 is conveyed from the paper tray 16 provided with the recording sheet 18 having a specified size as described above to the transfer unit 52 by the conveying roller pair 22.
[0029]
A fixing device (fixing means) 14 is disposed on the downstream side in the conveyance direction of the recording sheet 18 from the position where the transfer unit 52 is disposed. In the fixing device 14, a predetermined image is formed on the recording sheet 18 by performing a fixing process on the paper 34 onto which the final toner image has been transferred. The recording sheet on which the image is formed is conveyed while the conveyance path surface (sheet conveyance path surface) indicated by P in the drawing is sandwiched between conveyance roller pairs 22a to 22c one after another, and is discharged to the discharge tray 26.
[0030]
The fixing device 14 has a heating roller (fixing rotator) 56 for fusing and fixing the toner 54 transferred onto the paper 18 to the paper 18, and for sandwiching and pressing the paper 18 together with the heating roller 56. And a pressure roller (fixing rotator) 58. The heating roller 56 is configured as an iron metal hollow gold having a thickness of about 3 mm. Further, a rubber layer having a thickness of about 2 mm is formed on the contact surface with the sheet 18, that is, the surface of the heating roller 56, and a halogen lamp (heat source) is built in the heating roller 56. The pressure roller 58 is formed with a rubber layer having a thickness of about 1 mm around the core metal such as iron, and a halogen lamp (heat source) is provided inside the pressure roller 58. Built in. The pressure roller 58 presses the heating roller 56 with a constant pressure by a spring. As a result, the recording sheet 18 is nipped and conveyed by the heating roller 56 and the pressure roller 58. Thus, when the recording sheet 18 passes between the heating roller 56 and the pressure roller 58, the toner 54 is pressure-melted and fixed on the paper 18.
[0031]
By the way, in this image forming apparatus 10, in order to prevent adverse effects on peripheral components due to heat from the fixing device 14, (1) the surrounding atmosphere heated by the fixing device 14 is discharged out of the device 10, and (2) ▼ Measures are taken to prevent the temperature of peripheral parts from rising. Hereinafter, these will be described.
[0032]
FIG. 7 illustrates the configuration around the fixing device 14 in more detail. 8 is a side view of the side casing 12S indicated by the oblique lines of the image forming apparatus 10 as viewed from the direction of the thick arrow V in FIG. FIG. 9 is a side view of the image forming apparatus 10 with the side casing 12S shown by hatching removed, as viewed from the direction of the thick arrow V in FIG. As shown in these drawings, two axial fans (exhaust means) 70 a and 70 b are provided around the fixing device 14.
[0033]
One axial fan 70a is provided outside the maximum width L of the recording sheet 18 to be conveyed (see FIG. 9), and through a slit 74 provided in the side casing 12S (see FIG. 8), the apparatus. The atmosphere in 10 is discharged to the outside.
[0034]
The other axial fan 70b is provided inside the maximum width L of the recording sheet 18 to be conveyed (see FIG. 9), and a slit 72 (see FIG. 9) provided in the conveying plate 23 that forms a part of the conveying path surface. 9), and the atmosphere in the apparatus 10 is discharged to the outside through a slit 73 provided in the side casing 12S (see FIG. 8). The axial flow fan 70b has a size of 60 × 60 × 15 [mm] in length.
[0035]
Thus, the exhaust from the axial fan 70b is blown at right angles to the transport path surface, passes through the transport path surface, and is discharged to the outside of the apparatus 10. Further, the position where the axial fan b is provided is a location corresponding to the vicinity of the substantially central portion of the maximum width L of the recording sheet 18. As a result, compared with the axial fan 70a provided outside the maximum width L, for example, the atmosphere in the device 10 having a higher temperature can be exhausted, and thus the exhaust efficiency is high.
[0036]
A plurality of ribs 230 are provided in the transport plate 23 along the transport direction for reducing friction with the transported recording sheet 18. Of the slits 73 provided in the side casing 12S, a plurality of horizontally long vent holes are actually formed in a portion 73R, and a horizontally long recess is formed as a dummy in the other portion 73D. Further, regardless of whether or not the recording sheet 18 is conveyed, when the fixing device 14 is operated, any of the fans 70a and 70b is rotating.
[0037]
Prevention of Temperature Rise of Peripheral Parts As shown in FIG. 7, an aluminum tape (heat shield member) 71 is affixed to a portion of the intermediate transfer member cleaner (peripheral parts) 50 facing the fixing device 14. By applying the aluminum tape 71, the internal temperature of the intermediate transfer body cleaner 50 could be lowered by about 5 [° C.] compared to the conventional case.
[0038]
【The invention's effect】
As described above in detail, according to the present invention, an image forming apparatus having a layout excellent in exhaust efficiency can be provided. As a result, it is possible to effectively prevent an adverse effect due to heat from the fixing device while achieving a simple configuration, miniaturization of the device, energy saving, and the like.
[Brief description of the drawings]
FIG. 1 illustrates a layout of an image forming apparatus according to the present invention.
FIG. 2 illustrates a layout of another image forming apparatus of the present invention.
FIG. 3 illustrates a layout of another image forming apparatus of the present invention.
FIG. 4 illustrates a layout of another image forming apparatus of the present invention.
FIG. 5 illustrates the present invention (Claim 6).
FIG. 6 is a schematic cross-sectional view of an image forming apparatus to which the present invention can be applied.
FIG. 7 is a partially enlarged view of FIG. 6;
FIG. 8 illustrates a side casing of the image forming apparatus.
FIG. 9 illustrates a conveyance path surface inside the image forming apparatus.
FIG. 10 illustrates a layout of a conventional image forming apparatus.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 14 ... Fixing device (fixing means), P ... Conveyance path surface (sheet conveyance path surface), 22a-c ... Conveyance roll pair, 23 ... Conveyance plate, 70b ... Axial fan (exhaust means), 72, 73 ... Slit, 71 ... Aluminum tape (heat shield member), 50 ... Cleaner for intermediate transfer member (peripheral parts)

Claims (2)

A fixing unit having an internal heat source for fixing an unfixed toner image on a recording sheet, a sheet conveyance path surface for conveying a recording sheet fixed by the fixing unit to a discharge port, and heat from the fixing unit. In an image forming apparatus comprising first and second exhaust means for exhausting the ambient atmosphere to the outside of the apparatus,
The fixing unit conveys and fixes the recording sheet in the horizontal direction, and the sheet conveyance path surface after fixing is formed upward.
The first exhaust means exists above the fixing means and on the normal line of the sheet conveyance path surface after the fixing, and the direction of the intake air flow or exhaust flow of the first exhaust means is conveyed. passes to be perpendicular to the sheet conveying path plane to intersect at least a part of the sheet is exhausted directly from the casing of the slit to form a sheet conveying road,
The second exhaust means is provided outside the maximum width of the recording sheet to be conveyed, and the intake flow or exhaust flow of the second exhaust means does not intersect the sheet conveyance path surface. An image forming apparatus.   2. The image forming apparatus according to claim 1, wherein the first and second exhaust units exhaust the ambient atmosphere to the outside of the apparatus even when the recording sheet is transported to the sheet transport path surface. .

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