Sheet cooling device and image forming apparatus

Abstract

To provide a sheet cooling device and an image forming apparatus that can prevent deterioration in tacking prevention performance and defective loading.SOLUTION: A sheet cooling device comprises: fixing means 6 that fixes a toner image to a sheet; ejection means 71 that ejects the sheet to which the toner image is fixed; loading means 8 on which the sheet P ejected by the ejection means 71 is loaded; blowing means 10 that sends air; a first draft air duct that guides the air from the blowing means 10 so that the air passes through the ejection means 71; and a second draft air duct that guides the air to prevent it from flowing into the loading means 8, with the first draft air duct closed by the sheet P ejected by the ejection means 71.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] This invention relates to a sheet cooling device and an image forming apparatus for cooling a sheet when discharging a sheet such as printed paper on which a toner image has been fixed by a fixing device in an image forming apparatus.

Background Art

[0002] An electrophotographic image forming apparatus such as an MFP (Multifunction Peripherals) includes a fixing device for fixing a toner image transferred onto a sheet such as printed paper. The fixing device fixes an image on the sheet by performing a heat treatment and a pressure treatment on the sheet onto which the toner image has been transferred. Then, the image forming apparatus discharges the sheet on which the toner image has been fixed to a sheet stacking unit through a discharge unit.

[0003] By the way, an image forming apparatus such as an MFP generally has a scanner unit at the upper part of the apparatus main body and a printer unit at the central part of the apparatus main body, and arranges a sheet stacking unit in the space between the scanner unit and the printer unit. Therefore, since the sheet stacking unit is arranged in an enclosed space where the upper, lower, back, and sheet discharge sides are closed, the sheet stacking space, which is the upper space of the sheet stacking unit, tends to be in a high-temperature state.

[0004] When the sheet discharged to the sheet stacking unit is exposed to a high-temperature atmosphere, the toner melts, and a tacking phenomenon occurs where two continuously discharged sheets stick to each other. In particular, in recent years, there has been a tendency to reduce the melting point of the toner to lower the fixing temperature and achieve energy saving of the image forming apparatus, and the possibility of frequent occurrence of the tacking phenomenon has been increasing with the reduction of the melting point of the toner.

[0005] Conventionally, techniques for cooling the sheet stacking space have been proposed to prevent the tacking phenomenon described above (for example, Patent Documents 1 and 2). Patent Document 1 describes a configuration in which a cooling means is provided that blows cooling air onto the upper surface of the paper being discharged to the stacking section from a cooling fan attached to the main body of the device. Patent Document 2 also describes a configuration in which the air outlet guided by the air blowing means has an opening facing the stacking section and an opening facing the paper discharge path. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2021-050050 [Patent Document 2] Japanese Patent Publication No. 2010-266799 [Overview of the Initiative] [Problems that the invention aims to solve]

[0007] However, in a configuration where air is blown from above, as in Patent Document 1, pressure exceeding the weight of the ejected paper is applied, and the tacking prevention performance deteriorates as the number of stacked sheets increases. In addition, because air is blown from above, the ejected paper tends to sag, and there is a problem of poor stacking where the paper curls up in the stacking section.

[0008] Furthermore, in configurations where air is flowed through the stacking section, as in Patent Document 2, when the spacing between sheets of paper narrows in high-speed machines, the next sheet of paper can block the leading edge, causing air to begin flowing through the stacking section before the paper reaches the output tray, resulting in a stacking failure.

[0009] This invention was made to solve these problems and aims to provide a sheet cooling device and an image forming device that can prevent deterioration of tacking prevention performance and loading defects. [Means for solving the problem]

[0010] The above objectives will be achieved by the following means. (1) Fixing means for fixing the toner image onto the sheet, An ejection means for ejecting a sheet on which a toner image has been fixed by a fixing means, A loading means for loading sheets discharged by a discharge means, A means of blowing air, Air from the aforementioned blowing means Without flowing into the loading means, The discharge means The water then flows into a first suction area formed at a different location from the loading means, and flows out of the machine from the first suction area. A first air passage that guides the air in that manner, With the first air passage blocked by the sheet discharged by the aforementioned discharge means, From the aforementioned air supply means air The fluid does not flow into the loading means, but instead flows into a second suction area formed at a different location from the loading means, and then flows out of the machine from the second suction area. so Air The second air duct to be guided, A sheet cooling device characterized by having the following features. ( 2 ) A fixing means for fixing the toner image onto the sheet, An ejection means for ejecting a sheet on which a toner image has been fixed by a fixing means, A loading means for loading sheets discharged by a discharge means, A means of blowing air, A first air passage that guides the air from the blowing means to pass through the discharge means, With the first air passage blocked by the sheet discharged by the discharge means, a second air passage guides the air to suppress the inflow into the loading means, Equipped with, When there is no paper in the discharge means, the first air passage guides the air from below to above the discharge means, and when the first air passage is blocked by the sheet, the second air passage guides the air below the discharge means to the side opposite the loading means. The air guided by the first and second air passages is collected by a suction fan. Characterized by Seat cooling device. ( 3 The blowing means is mounted on the loading means, and the air blown by the blowing means passes below the loading means to the first Airflow The road guides the user to the means of discharge (as described in item 1 above). or 2 The sheet cooling device described above. (4) The air collected by the suction fan is discharged outside the machine via a filter. 2 The sheet cooling device described above. (5) The air blown by the blowing means is taken in from outside the image forming apparatus. The sheet cooling device according to item 1 or 2 of the preceding paragraph. (6) The discharging means includes a paper discharge roller that supports the paper to be discharged. The air guided to the discharging means by the first air passage directly cools the paper discharge roller. The sheet cooling device according to item 1 or 2 of the preceding paragraph. (7) Item 1 of the preceding paragraph or 2 An image forming apparatus provided with the sheet cooling device according to the preceding paragraph.

Effect of the Invention

[0011] According to the inventions described in items (1) and (7) of the preceding paragraph, since the air from the blowing means is guided by the first air passage so as to pass through the discharging means, when the sheet is not passing through the discharging means, the discharging means is cooled by the air and then the sheet passing through the discharging means is indirectly cooled, and when the sheet is passing through the discharging means, the paper is directly cooled by the air. Thus, since it is not a configuration in which air is blown onto the upper surface of the sheet discharged to the stacking space for cooling, it is possible to prevent deterioration of the anti-tacking performance caused by the blowing of air from the upper surface and stacking failure due to paper curling.

[0012] Furthermore, in a state where the first air passage is blocked by the sheet discharged by the discharging means, the air is guided by the second air passage and the inflow into the stacking means is suppressed, so that it is possible to prevent stacking failure caused by the flow of air into the stacking means.

[0013] In the preceding paragraph ( 3 ) According to the invention described, the blowing means is mounted on the stacking means, and the air blown by the blowing means is guided to the discharging means through the first flow passage via the lower side of the stacking means, so that the supply path of the air can be formed compactly using the stacking means.

[0014] In the preceding paragraph ( 2According to the invention described above, when the first air passage is blocked by the sheet, the air is guided by the second air passage to the side opposite the loading means below the discharge means and collected by the suction fan, thereby reliably suppressing the inflow of air into the loading means.

[0015] According to the invention described in item (4) above, the air collected by the suction fan is discharged outside the machine via a filter, so that the air can be discharged outside the machine with dirt, dust, and other debris removed.

[0016] According to the invention described in item (5) above, since the air blown by the blowing means is taken in from outside the image forming apparatus, the sheet can be cooled with fresh air.

[0017] According to the invention described in paragraph (6) above, the paper discharge roller is directly cooled by the air guided to the discharge means by the first air passage, so that the sheet in contact with the cooled paper discharge roller can be efficiently cooled. [Brief explanation of the drawing]

[0018] [Figure 1] This is a schematic diagram showing the configuration of a tandem-type color printer, which is an example of an image forming apparatus equipped with a sheet cooling device according to one embodiment of the present invention. [Figure 2] This is a vertical cross-sectional view of the paper loading and paper output sections, seen from the front. [Figure 3] This is a view of the paper loading section and paper output section from the bottom. [Figure 4] (a) is a perspective view of the loading section as seen from the blower fan side, and (b) is a perspective view of the loading section as seen from the blower fan side with the top and bottom reversed. [Figure 5] (a) is a cross-sectional view of the paper ejection section and the area below it when there is no paper to be ejected, and (b) is a cross-sectional view of the same section when paper is being ejected. [Figure 6] This is a longitudinal cross-sectional view of the paper output section. [Figure 7]This is a cross-sectional view showing the upper suction area and the airflow path into the upper suction area. [Modes for carrying out the invention]

[0019] Hereinafter, embodiments of this invention will be described based on the drawings.

[0020] Figure 1 is a schematic diagram showing the configuration of a tandem-type color printer, which is an example of an image forming apparatus equipped with a sheet cooling device according to one embodiment of the present invention.

[0021] This image forming apparatus is equipped with a paper feed tray 1 at the bottom, a printer unit 2 above the paper feed tray 1, and a scanner unit 3, which is a document reading device, at the very top.

[0022] The printer unit 2 prints image data read by the scanner unit 3 and print data transmitted from a terminal device (not shown) onto a sheet of paper, which is an example of a sheet. Specifically, the toner images of each color formed on the four photosensitive drums 22 by exposure in the exposure device 21 are superimposed on the intermediate transfer belt 23, and the superimposed toner images are transferred to the paper that has been transported from the paper feed tray 1 through the transport path 4 by the secondary transfer roller 5.

[0023] The paper on which the toner image has been formed is transported to the fuser unit 6, where it is heated and pressurized to fix the toner image to the paper. The paper with the fixed toner image is sent to the paper discharge unit 7, where it is discharged with the toner image formed side facing downwards into the output tray 81 formed on the upper surface of the stacking unit 8 by the paper discharge roller pair 71 of the paper discharge unit 7. If there are multiple sheets to print, the above process is performed continuously, and the paper is continuously discharged from the paper discharge unit 7 into the output tray 81 and stacked sequentially in the stacking unit 8.

[0024] As shown in Figures 5 and 6, the paper output roller pair 71 consists of a drive roller 71a attached to the upper drive shaft 75 and a plurality of paper output rollers 71b for supporting the paper, which are arranged at intervals in the axial direction of the drive roller 71a and in contact with the drive roller 71a from below. In Figure 1, the roller pair 72 above the paper output roller pair 71 is a reversing roller pair for reversing the paper in the case of double-sided copying.

[0025] A hollow section 9 is formed inside the lower part of the loading section 8, and a blower fan 10, which is a means of blowing air, is mounted at the end of the hollow section 9 opposite to the paper discharge section 7. Cooling air drawn in from outside the machine by this blower fan 10 is sent through the hollow section 9 below the loading section 8 toward the paper discharge section 7, as shown by arrow A1 in Figure 1.

[0026] Figure 2 is a vertical cross-sectional view of the loading section 8 and paper discharge section 7 as seen from the front, Figure 3 is a view of the loading section 8 and paper discharge section 7 as seen from the bottom, Figure 4(a) is a perspective view of the loading section 8 as seen from the blower fan 10 side, and Figure 4(b) is a perspective view of the loading section 8 as seen from the blower fan 10 side with the top and bottom reversed.

[0027] As shown in Figure 4, the stacking section 8 is formed in an inverted dish shape with an open bottom in cross-section. By connecting it to the image forming apparatus at multiple points, a duct 100 having the aforementioned hollow section 9 is formed on the back side of the stacking section 8, as shown in Figures 2 and 3. Furthermore, the height of the stacking section 8 is higher on the side with the blower fan 10 and continuously decreases towards the side with the paper discharge section 7, so that the paper output tray 81 is formed on an inclined surface with the blower fan 10 side being higher and the paper discharge section 7 side being lower. Also, as shown in Figures 3 and 4, the blower fan 10 is positioned in the center of the stacking section 8 in the front-to-back direction (up-to-down direction in Figure 3), and the length of the stacking section 8 in the front-to-back direction increases from the blower fan 10 towards the side with the paper discharge section 7, with the end on the discharge section 7 side being approximately the same length as the paper passage width of the paper discharge section 7.

[0028] As shown in Figure 2, the duct outlet 100a inside the loading section 8 is erected toward the paper discharge section 7 and communicates with the lower end of the vertical flow section 101 that extends in the axial direction of the paper discharge roller pair 71. On the other hand, the upper end of the vertical flow section 101 opens directly below the paper discharge roller pair 71. Therefore, as shown by arrow A2 in Figure 2, the air taken into the duct 100 of the loading section 8 from outside the image forming apparatus by the blower fan 10 is supplied through the duct 100 toward the duct outlet 100a as shown by arrow A1, flows from the duct outlet 100a to the lower part of the vertical flow section 101, rises up the vertical flow section 101 and flows toward the paper discharge roller pair 71 and its surroundings, and comes into contact with the paper discharge roller 71b on the lower side of the paper discharge roller pair 71, directly cooling the paper discharge roller 71b.

[0029] In this embodiment, the blower fan 10 is mounted on the loading section 8, and the air blown by the blower fan 10 is guided to the discharge roller pair 71 via the lower part of the loading section 8. Thus, the air supply path can be compactly formed using the loading section 8.

[0030] Figure 5(a) is a cross-sectional view of the paper ejection section 7 and the area below it when there is no paper to be ejected, and Figure 5(b) is a cross-sectional view when paper is being ejected.

[0031] As shown in these figures, the paper discharge section 7 has an upper suction area 102 that is longer in the longitudinal direction of the paper discharge roller pair 71 (the paper thickness direction in Figure 5) and is located diagonally above the paper transport direction upstream of the paper discharge roller pair 71. This upper suction area 102 is in communication with the space where the paper discharge roller pair 71 is located. In Figures 5(a) and 5(b), the cross-section of the upper suction area 102 is shown in gray.

[0032] On the other hand, below the upper suction area 102, separated by the paper transport path, a lower suction area 103 is formed parallel to the upper suction area 102. In Figures 5(a) and 5(b), the cross-section of the lower suction area 103 is shown in gray, similar to the upper suction area 102. This lower suction area 103 is formed on the opposite side of the stacking section 8, separated by the vertical flow section 101. Furthermore, as shown in Figures 5 and 6, multiple openings 103a are formed along the length of the lower suction area 103 on the side wall of the lower suction area 103 on the vertical flow section 101 side. These openings 103a allow the lower suction area 103 to communicate with the vertical flow section 101, and enable air rising in the vertical flow section 101 to flow into the lower suction area 103 through the openings 103a.

[0033] In Figure 5(b), the symbol P represents a sheet of paper being ejected by the paper ejection roller pair 71. In Figures 5(a) and 5(b), the symbol 73 is a switching claw for switching between the transport of the paper P to the paper ejection roller pair 71 and the transport of the paper ejection roller pair 72, and the symbol 74 is a transport roller that transports the paper P to the paper ejection roller pair 71.

[0034] As shown in Figure 7, a suction fan 76 is mounted at the rear of the upper suction area 102 and the lower suction area 103 (the rear in the front-to-back direction of the image forming apparatus) in a manner that allows it to suck up air from within the upper suction area 102 and the lower suction area 103. A filter 77 is positioned downstream of the suction fan 76, and the air from the upper suction area 102 and the lower suction area 103 that has been sucked up by the suction fan 76 passes through the filter 77 to remove dust and debris, and is then discharged outside the machine as indicated by arrow A5 in Figure 7.

[0035] The presence of the blower fan 10, duct 100, vertical flow section 101, upper suction area 102, lower suction area 103, and suction fan 76, etc., forms two airflow passages, a first airflow passage and a second airflow passage, for the air that flows from the duct 100 into the vertical flow section 101 of the loading section 8. The first airflow passage is an airflow passage through which air that flows from the duct outlet 100a into the vertical flow section 101, rises up the vertical flow section 101 and flows to the paper discharge roller pair 71, passes through the paper discharge roller pair 71 and its vicinity as shown by arrow A3 in Figure 5(a), flows to the upper suction area 102, and is sucked up and collected by the suction fan 76. The second airflow passage, as indicated by arrow A4 in Figure 5(b), is an airflow passage through which air that has risen in the vertical flow section 101 flows through the opening 103a to the lower suction area 103, where it is sucked in and collected by the suction fan 76.

[0036] Next, we will explain the operation of the image forming apparatus shown in Figure 1 during sheet cooling.

[0037] The paper P, on which the toner image has been fixed by the fuser unit 6, is transported by the transport rollers 74, etc., to the output roller pair 71, and then discharged into the output tray 81 by the output roller pair 71. If multiple sheets of paper P are to be printed, the multiple sheets of paper P are discharged into the output tray 81 in sequence and stacked in the stacking unit 8.

[0038] Meanwhile, a blower fan 10 located at one end of the loading section 8 draws in fresh air from outside the image forming apparatus. The drawn-in air is then sent through the duct 100 of the loading section 8 towards the duct outlet 100a at the other end, and flows into the vertical flow section 101 from the duct outlet 100a.

[0039] The air flowing into the vertical circulation section 101 rises upward due to the supply pressure from the blower fan 10 and the suction force from the suction fans 76 located at the far ends of the upper suction area 102 and the lower suction area 103.

[0040] When the image-formed paper P is not being transported to the paper discharge roller pair 71, the air flows along the first airflow path indicated by arrow A3 in Figure 5(a). That is, the air rising in the vertical flow section 101 directly contacts the lower paper discharge roller 71b of the paper discharge roller pair 71, passes through the paper discharge roller pair 71 and its vicinity, cooling the paper discharge roller pair 71 and the transport path nearby, before flowing into the upper suction area 102. After the upper suction area 102 moves towards the suction fan 76, the air passes through the filter 77 and is discharged outside the machine in a clean state after removing dirt and dust. In other words, when the image-formed paper P is not being transported, the air passes through the first airflow path while performing a cooling function on the paper discharge roller pair 71 and its vicinity. Therefore, the paper P that subsequently passes through the roller pair 71 is cooled by the paper discharge roller pair 71, etc.

[0041] On the other hand, when the image-formed paper P is transported and discharged by the paper discharge roller pair 71, the air that flows from the duct outlet 100a into the vertical flow section 101 and rises through the vertical flow section 101 comes into contact with the paper discharge roller 71b of the paper discharge roller pair 71 and the underside of the paper P, cooling the paper. However, the paper P obstructs the air from passing through the paper discharge roller pair 71. As a result, the internal pressure of the air passage increases, and the air flows along the second air passage indicated by arrow A4 in Figure 5(b) through the opening 103a into the lower suction area 103. After moving the lower suction area 103 towards the suction fan, it passes through the filter 77 and is discharged outside the machine. In other words, when the image-formed paper P is being discharged, the air cools the paper as it passes through the second air passage.

[0042] In this embodiment, since a second air passage is formed in addition to the first air passage, even when the flow of air in the first air passage is obstructed by the paper P present on the paper discharge roller pair 71 and the internal pressure of the air passage increases, the air flows into the lower suction area 103 through the opening 103a of the second air passage and is discharged outside the machine, suppressing the flow into the loading section 8. Therefore, when the internal pressure of the air passage increases, the problem of air flowing into the loading section 8 and causing paper loading defects due to the lack of an escape route for the air can be reliably prevented. This is especially effective in preventing loading defects in high-speed machines where the spacing between sheets of paper is narrow.

[0043] Furthermore, since it does not have a configuration that blows air from above onto the paper P discharged into the stacking section 8, problems such as deterioration of tacking prevention performance as the number of stacked sheets increases, and paper curling in the stacking section 8 due to paper sagging during discharge do not occur.

[0044] Although embodiments of the present invention have been described above, the present invention is not limited to the above embodiments. For example, although a blower fan 10 is placed below the loading section 8 and air is blown below the loading section 8 by a duct 100, the position of the blower fan 10 is not limited to below the loading section 8. The air taken in from the blower fan 10 may be configured to pass through the paper discharge roller pair 71 from top to bottom, and a second air passage may be formed above the paper discharge roller pair 71 to suppress the inflow of air into the loading section 8. [Explanation of Symbols]

[0045] 1 Paper feed tray 2 Printer section 3 Scanners 4. Paper transport path 5. Secondary transfer roller 6. Fixing device 7 Paper output section 8 Loading section 81 Paper output tray 9 Hollow part 10. Blower fan 71 Paper output roller pair 71a Drive Roller 71b Paper Output Roller 75 Drive shaft 76 Suction fan 77 filters 100 duct 100a duct outlet 101 Vertical distribution department 102 Upper suction area 103 Lower suction area 103a aperture P Paper (sheet)

Claims

1. A fixing means for fixing the toner image onto the sheet, An ejection means for ejecting a sheet on which a toner image has been fixed by a fixing means, A loading means for loading sheets discharged by a discharge means, A means of blowing air, A first air passage guides the air from the blowing means so that it does not flow into the loading means, but passes through the discharge means and flows into a first suction area formed at a different location from the loading means, and flows out of the machine from the first suction area. With the first air passage blocked by the sheet discharged by the discharge means, a second air passage guides the air from the air passage to flow into a second suction area formed at a different location from the loading means, without flowing into the loading means, and to flow out of the machine from the second suction area. A sheet cooling device characterized by having the following features.

2. Fixing means for fixing a toner image onto a sheet, An ejection means for ejecting a sheet on which a toner image has been fixed by a fixing means, A loading means for loading sheets discharged by a discharge means, A means of blowing air, A first air passage that guides the air from the blowing means to pass through the discharge means, With the first air passage blocked by the sheet discharged by the discharge means, a second air passage guides the air to suppress the inflow into the loading means, Equipped with, When there is no paper in the discharge means, the first air passage guides the air from below to above the discharge means, and when the first air passage is blocked by the sheet, the second air passage guides the air below the discharge means to the side opposite the loading means. A sheet cooling device characterized in that the air guided by the first and second air passages is collected by a suction fan.

3. The seat cooling device according to claim 1 or 2, wherein the blowing means is mounted on the loading means, and the air blown by the blowing means is guided to the discharge means via the first air passage through the lower part of the loading means.

4. The seat cooling device according to claim 2, wherein the air recovered by the suction fan is discharged outside the machine via a filter.

5. The sheet cooling device according to claim 1 or 2, wherein the air blown by the blowing means is taken in from outside the image forming apparatus.

6. The discharge means includes a paper discharge roller that supports the paper to be discharged, The sheet cooling device according to claim 1 or 2, wherein the air guided to the discharge means by the first air passage directly cools the paper discharge roller.

7. An image forming apparatus comprising a sheet cooling device according to claim 1 or 2.

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