Image forming apparatus

Abstract

To provide an image forming apparatus capable of appropriately discharging air in a paper conveyance path.SOLUTION: An image forming apparatus includes a fixing device that fixes a toner image on a sheet P, a sheet conveyance path 21 through which the sheet P passing through the fixing device is conveyed, a first duct 41 provided above the sheet conveyance path 21 through which the sheet having passed through the fixing device is conveyed, and a second duct 42 provided below the sheet conveyance path 21 through which the sheet having passed through the fixing device is conveyed.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to an image forming apparatus that includes a paper transport path along which paper is transported. [Background technology]

[0002] In image forming devices, when a toner image is fixed onto paper, heat is applied, and moisture contained in the paper or air is released as water vapor, which can accumulate in the paper discharge path (transport path). The water vapor is hot, and if it remains inside the image forming device, it can cause the temperature to rise. Therefore, a method has been proposed to suppress the temperature rise by ejecting air to cool the fixing device and then exhausting that air (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2019-191287 Summary of the Invention [Problem to be solved by the invention]

[0004] A conventional image forming device includes a fixing device including a secondary transfer roller that transfers a toner image onto paper and a fixing roller that fixes the toner image onto the paper, a paper attraction fan unit that sucks air so that it passes through the secondary transfer roller, a guide member that directs the air discharged from the paper attraction fan unit toward the fixing roller, and a filter device that passes and discharges the air discharged from the guide member, and the guide member guides the air toward both ends of the fixing roller's rotation axis in a direction that intersects the rotation axis.

[0005] The image forming apparatus described above can cool the fixing device, but has a problem in that it cannot cool the paper transport path that is heated by the discharged paper.

[0006] However, when transporting sheets of paper continuously to increase processing speed, the distance between sheets of paper becomes narrower, blocking the air flow and causing air trapped in the paper transport path to be expelled from unintended locations.

[0007] The present disclosure has been made to solve the above-mentioned problems, and aims to provide an image forming apparatus that can properly discharge air from a paper transport path. [Means for solving the problem]

[0008] The image forming apparatus according to the present disclosure is an image forming apparatus comprising a fixing device that fixes a toner image onto paper and a paper transport path along which paper passes through the fixing device, and is characterized by comprising a first duct provided above the paper transport path along which paper is transported after passing through the fixing device, and a second duct provided below the paper transport path along which paper is transported after passing through the fixing device.

[0009] The image forming apparatus according to the present disclosure may be configured to include a suction amount adjustment unit that adjusts the amount of suction in the first duct and the second duct.

[0010] In the image forming apparatus according to the present disclosure, the suction amount adjustment unit may be configured to change the ratio of the suction amounts of the first duct and the second duct.

[0011] In the image forming apparatus according to the present disclosure, the suction amount adjustment unit may be configured to set the amount of suction in the first duct and the second duct based on the distance between sheets transported on the sheet transport path.

[0012] In the image forming apparatus according to the present disclosure, the suction amount adjustment unit may be configured to increase the suction amount of the second duct as the distance between sheets transported on the sheet transport path becomes shorter.

[0013] In the image forming apparatus according to the present disclosure, the suction amount adjustment unit may be configured to set the suction amount in the first duct and the second duct based on the width direction length of the paper transported on the paper transport path.

[0014] In the image forming apparatus according to the present disclosure, the suction amount adjustment unit may be configured to set the suction amount in the first duct and the second duct based on the transport speed of the paper transported in the paper transport path.

[0015] The image forming apparatus according to the present disclosure may be configured to include fans connected to the exhaust ports of the first duct and the second duct.

[0016] In the image forming apparatus according to the present disclosure, the first duct may be provided at the top of the housing.

[0017] In the image forming apparatus according to the present disclosure, the first duct and the second duct may be configured to extend along the width direction of the paper so as to be longer than the maximum width of the paper. [Effects of the Invention]

[0018] According to the present disclosure, by providing a first duct and a second duct above and below the paper transport path, exhaust air that rises upward due to heat, as well as exhaust air that is blocked by the paper and remains below, can be efficiently exhausted. [Brief explanation of the drawings]

[0019] [Figure 1] 1 is a schematic cross-sectional view illustrating a configuration of an image forming apparatus according to an embodiment of the present disclosure. [Figure 2] FIG. 2 is a schematic structural diagram showing the structure in the vicinity of the first duct and the second duct. [Figure 3] 1 is a schematic configuration diagram of an image forming apparatus according to an embodiment of the present disclosure. [Figure 4] FIG. 1 is an explanatory diagram (part 1) showing the state of paper transport on the paper transport path. [Figure 5]FIG. 2 is an explanatory diagram (part 2) showing the state of paper transport on the paper transport path. [Figure 6] FIG. 10 is an explanatory diagram (part 3) showing the state of paper transport on the paper transport path. [Figure 7] FIG. 10 is a flowchart showing a process flow relating to suction amount adjustment in the image forming apparatus according to the embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0020] Hereinafter, an image forming apparatus according to an embodiment of the present disclosure will be described with reference to the drawings.

[0021] FIG. 1 is a schematic cross-sectional view showing the configuration of an image forming apparatus according to an embodiment of the present disclosure.

[0022] The image forming device 100 is a multifunction device having a copy function, a scanner function, a facsimile function, and a printer function, and transmits an image of a document read by the image reading device 130 to an external device, and forms an image of a document read by the image reading device 130 or an image received from an external device in color or monochrome on a recording medium such as paper.

[0023] An original transport device 110 that is supported so as to be able to open and close freely is provided above the image reading device 130. The original transport device 110 transports one or more originals one by one. The image reading device 130 scans a scanning optical system 130b to read an original placed on an original placement table 130a, or reads an original transported by the original transport device 110 to generate image data.

[0024] The image forming apparatus 100 is provided with a fixing device 1, a developing device 2, a photosensitive drum 3, a drum cleaning device 4, a charger 5, an intermediate transfer belt device 7, a secondary transfer device 11, an optical scanning device 12, a paper feed section 18, and a paper output tray 19.

[0025] Image forming apparatus 100 handles image data corresponding to color images using black (K), cyan (C), magenta (M), and yellow (Y), or monochrome images using a single color (e.g., black). Image forming apparatus 100 is provided with four developing devices 2, four photosensitive drums 3, four drum cleaning devices 4, and four chargers 5 for forming four types of toner images, and four image stations Pa, Pb, Pc, and Pd are configured corresponding to black, cyan, magenta, and yellow, respectively.

[0026] The charger 5 uniformly charges the surface of the photosensitive drum 3 to a predetermined potential. The optical scanning device 12 exposes the surface of the photosensitive drum 3 to light to form an electrostatic latent image. The developing device 2 develops the electrostatic latent image on the surface of the photosensitive drum 3 to form a toner image on the surface of the photosensitive drum 3. The drum cleaning device 4 removes and collects residual toner on the surface of the photosensitive drum 3. Through the series of operations described above, a toner image of each color is formed on the surface of each photosensitive drum 3.

[0027] The intermediate transfer belt device 7 includes an intermediate transfer roller 6, an endless intermediate transfer belt 71, an intermediate transfer drive roller 72, an intermediate transfer driven roller 73, and a cleaning device 9. Four intermediate transfer rollers 6 are provided inside the intermediate transfer belt 71 so as to form four types of toner images corresponding to each color. The intermediate transfer rollers 6 transfer the toner images of each color formed on the surface of the photosensitive drum 3 onto the intermediate transfer belt 71, which moves around in a circular motion.

[0028] The intermediate transfer belt 71 is stretched over an intermediate transfer drive roller 72 and an intermediate transfer driven roller 73. In the image forming apparatus 100, the toner images of each color formed on the surface of each photosensitive drum 3 are sequentially transferred and superimposed to form a color toner image on the surface of the intermediate transfer belt 71. The cleaning device 9 removes and collects waste toner remaining on the surface of the intermediate transfer belt 71 without being transferred to paper.

[0029] The secondary transfer device 11 sandwiches and transports a sheet of paper transported through the paper transport path 21 in the transfer nip portion TN between the secondary transfer roller 11a and the intermediate transfer belt 71. When the sheet of paper passes through the transfer nip portion TN, the toner image on the surface of the intermediate transfer belt 71 is transferred onto the sheet of paper, and the sheet of paper is transported to the fixing device 1.

[0030] The fixing device 1 includes a fixing roller 31 and a pressure roller 32. The fixing device 1 sandwiches a sheet of paper onto which a toner image has been transferred in a nip portion N between the fixing roller 31 and the pressure roller 32, and applies heat and pressure to fix the toner image to the sheet. Note that while FIG. 1 shows a configuration using the fixing roller 31, a fixing belt may be provided instead of the fixing roller 31, and a fixing pad disposed inside may press the pressure roller 32 via the fixing belt.

[0031] The paper feed unit 18 includes a paper feed cassette that holds recording media (paper) used for image formation, and is provided below the optical scanning device 12. The paper is pulled out of the paper feed unit 18 by a pickup roller 16 and transported to a paper transport path 21. The paper transported to the paper transport path 21 passes through the secondary transfer device 11 and the fixing device 1, and is then discharged to a paper output tray 19 by a discharge roller 17.

[0032] Conveyance rollers 13, registration rollers 14, and discharge rollers 17 are arranged on paper conveyance path 21. Conveyance rollers 13 facilitate the conveyance of paper. Registration rollers 14 convey paper at a speed equal to the process speed at which an image is formed on the paper. Registration rollers 14 are provided between paper feed unit 18 and secondary transfer device 11, and adjust the timing of paper conveyance so that the toner image is transferred to the paper by secondary transfer device 11. For example, registration rollers 14 wait (temporarily stop) while clamping paper conveyed from paper feed unit 18, and then start conveying the paper at a constant speed in synchronization with secondary transfer device 11.

[0033] When an image is to be formed on the back side of the paper in addition to the front side, the conveying direction of the paper is changed by discharge rollers 17, and the paper is conveyed to reversing conveying path 22. In reversing conveying path 22, the paper is guided up to registration rollers 14 in a reversed state by reversing conveying rollers 15. Image forming apparatus 100 forms an image on the back side of the paper guided to registration rollers 14 in the same manner as on the front side, and discharges the paper to discharge tray 19.

[0034] A first duct 41 and a second duct 42 are provided near the paper transport path 21 between the fixing device 1 and the discharge roller 17 to exhaust air sucked from the paper transport path 21. Specifically, the first duct 41 is provided above the paper transport path 21 after the fixing device 1, and the second duct 42 is provided below the paper transport path 21 after the fixing device 1. The first duct 41 is preferably provided at the top of a housing that houses the fixing device 1 and other components. This arrangement allows the air taken in by the first duct 41 to be efficiently exhausted without remaining in the housing. For ease of explanation, the first duct 41 and the second duct 42 may hereinafter be collectively referred to as "ducts."

[0035] FIG. 2 is a schematic structural diagram showing the structure in the vicinity of the first duct and the second duct.

[0036] Paper guides that guide paper P are provided in paper transport path 21, and paper P is transported so as to pass through gaps between the paper guides. In the paper guides, holes or slits for allowing air to pass through are appropriately provided in the portions corresponding to first duct 41 and second duct 42.

[0037] The first duct 41 and the second duct 42 are appropriately provided with holes and the like for taking in air from the paper transport path 21. The first duct 41 and the second duct 42 extend in the width direction of the paper P, and the portions facing the paper transport path 21 are longer than the maximum width of the paper P being transported. By providing the first duct 41 and the second duct 42 above and below the paper transport path 21 in this way, it is possible to efficiently exhaust both exhaust air that rises upward due to heat and exhaust air that is blocked by the paper and remains below. Furthermore, by making the first duct 41 and the second duct 42 longer than the maximum width of the paper P, it is possible to make the first duct 41 and the second duct 42 have intake paths that correspond to the entire maximum width of the paper P.

[0038] The exhaust port (first exhaust port 41a) of the first duct 41 and the exhaust port (second exhaust port 42a) of the second duct 42 are connected to a common space (fan front chamber 44). Air sent into the fan front chamber 44 is exhausted to the outside of the housing via the fan 43. By providing one fan 43 common to the two ducts in this way, it is possible to reduce costs and perform exhaust efficiently.

[0039] A shutter 51, which is part of the suction volume adjuster 50, is provided in a portion facing the first exhaust port 41a and the second exhaust port 42a. The shutter 51 is connected to a drive source 52 and moves in a direction (the direction of arrow S in FIG. 2) to open and close the first exhaust port 41a and the second exhaust port 42a, as shown by the dashed line. The amount of air (suction volume) sent into the fan front chamber 44 of the first duct 41 and the second duct 42 increases or decreases as the shutter 51 opens and closes the first exhaust port 41a and the second exhaust port 42a.

[0040] The shutter 51 may be configured to open in stages so that it does not completely close the first exhaust port 41a and the second exhaust port 42a when it moves, but stops when the open area (opening area) is reduced by partially closing the first exhaust port 41a and the second exhaust port 42a. Alternatively, a corresponding shutter 51 may be provided for each of the first exhaust port 41a and the second exhaust port 42a so that they can be opened and closed individually. As shown in FIG. 2 , if a common shutter 51 is used for the first exhaust port 41a and the second exhaust port 42a, when the shutter 51 moves to reduce the opening area of ​​one port, the opening area of ​​the other port increases. By adjusting the opening area with the shutter 51, the suction volume of the first duct 41 and the second duct 42 can be increased or decreased, thereby changing the ratio of the suction volumes. In this way, the suction volume adjustment unit 50 can adjust the suction volumes of the first duct 41 and the second duct 42 to appropriate levels. Furthermore, by changing the ratio of the suction volumes, it is possible to select the duct that is primarily used depending on the operating conditions.

[0041] The driving source 52 may be selected appropriately depending on the configuration of the shutter 51, and for example, a solenoid or a motor connected via a rack and pinion can be applied.

[0042] Fig. 3 is a schematic configuration diagram of an image forming apparatus according to an embodiment of the present disclosure. Note that Fig. 3 shows only a portion of image forming apparatus 100, and other members not shown in Fig. 3 may be included as appropriate.

[0043] Image forming apparatus 100 includes control unit 60 in addition to the above-described fixing device 1, paper transport path 21, first duct 41, second duct 42, fan 43, and suction amount adjustment unit 50. Control unit 60 is a microcomputer such as a CPU mounted on image forming apparatus 100, and controls the operation of image forming apparatus 100. Specifically, control unit 60 instructs suction amount adjustment unit 50 to adjust the amount of suction in the duct depending on the paper transport status on paper transport path 21. Next, the paper transport status on paper transport path 21 will be described with reference to FIGS. 4 to 6.

[0044] Figure 4 is an explanatory diagram (part 1) showing the paper transport status on the paper transport path, Figure 5 is an explanatory diagram (part 2) showing the paper transport status on the paper transport path, and Figure 6 is an explanatory diagram (part 3) showing the paper transport status on the paper transport path.

[0045] 4 to 6, the paper transport path 21 along which a plurality of papers P are transported successively is shown schematically.

[0046] 4 shows a state in which the processing speed (corresponding to the number of sheets P transported per unit time) is set to high, and the distance between large-sized sheets P (first sheet-to-sheet distance KL1) is narrow. Note that the sheet-to-sheet distance corresponds to the distance from the rear edge of the previous sheet to the front edge of the following sheet.

[0047] 5 differs from FIG. 4 in that the size of the paper P is smaller. Because the processing speed is the same, the distance between the leading edges of successive sheets of paper P is set to be the same, and as a result of the smaller size of the paper P, the distance between the sheets of paper P (second inter-paper distance KL2) is wider than in the situation shown in FIG.

[0048] 6 differs from FIG. 4 in that the processing speed is slower. Because the processing speed is slower, the distance between the leading edges of successive sheets of paper P is set to be wider, and the distance between sheets of paper P (third inter-sheet distance KL3) is wider than in the situation shown in FIG. 4 and narrower than in the situation shown in FIG. 5.

[0049] When multiple sheets of paper P are being transported along the paper transport path 21, the air inside the paper transport path 21 is prevented from moving by the sheets of paper P, and moves from below upward through the gaps between the sheets of paper P. As such, the ease with which air can move within the paper transport path 21 is affected by the distance between the sheets of paper P, and by determining this based on this, an appropriate amount of suction can be set. In this embodiment, the distance between the sheets of paper P is calculated based on the processing speed and the size of the sheets of paper P, and the transport status of the sheets of paper P is grasped.

[0050] As shown in Fig. 4, when the distance between the sheets is narrow, air tends to stagnate below the sheets P, so it is preferable to increase the amount of suction in the second duct 42. Also, as shown in Fig. 5, when the distance between the sheets is wide, air tends to pass above the sheets P, so it is preferable to increase the amount of suction in the first duct 41. Furthermore, as shown in Fig. 6, when the distance between the sheets is neither too narrow nor too wide, air is dispersed above and below the sheets P, so it is preferable to set the amount of suction in the first duct 41 and the second duct 42 to be approximately the same.

[0051] FIG. 7 is a flowchart showing a process flow relating to suction amount adjustment in the image forming apparatus according to the embodiment of the present disclosure.

[0052] In step S01, the control unit 60 receives a printing (image formation) instruction.

[0053] In step S02, the control unit 60 acquires printing conditions. Here, the printing conditions include the number and size of sheets to be printed, the orientation of the sheets to be transported, and the processing speed. The control unit 60 adjusts the suction amount and ratio in the first duct 41 and the second duct 42 based on the acquired printing conditions. The suction amount and ratio may be set appropriately depending on the distance between the sheets.

[0054] In step S03, the suction amount adjustment unit 50 adjusts the suction amount. Specifically, the suction amount adjustment unit 50 increases the suction amount of the second duct 42 as the distance between the sheets P transported on the sheet transport path 21 decreases. In addition, the suction amount of the first duct 41 may be decreased accordingly. In this way, as the distance between the sheets decreases, the amount of exhaust air remaining below increases, and this can be appropriately addressed by increasing the suction amount of the second duct 42.

[0055] Furthermore, since the size of the gap in the width direction varies depending on the paper size and the orientation of the paper being transported, even if the distance between the papers P is the same, the suction amount of the second duct 42 may be increased as the length of the paper P in the width direction increases. Furthermore, even if the distance between the papers P is the same, the suction amount of the second duct 42 may be increased as the transport speed of the paper P increases.

[0056] In step S04, printing starts and the process ends.

[0057] In the present embodiment, a configuration in which the fan 43 is provided common to the first duct 41 and the second duct 42 has been described, but the present invention is not limited to this, and fans connected individually to the first duct 41 and the second duct 42 may be provided. In this case, the suction volume adjustment unit 50 only needs to control the operation of each fan, and adjust the suction volume by controlling the rotation speed of the fan, etc.

[0058] It should be noted that the embodiments disclosed herein are illustrative in all respects and are not intended to be limiting. Therefore, the technical scope of the present disclosure should not be interpreted solely by the above-described embodiments, but should be defined based on the claims. Furthermore, all modifications within the scope and meaning equivalent to the claims are included. [Explanation of symbols]

[0059] 1 Fixing device 21 Paper transport path 41 First Duct 41a First exhaust port 42 Second Duct 42a Second exhaust port 43 Fans 50 Suction amount adjustment section 60 Control Unit 100 Image forming device

Claims

1. a fixing device that fixes the toner image on the paper; a paper transport path along which paper passing through the fixing device is transported, a first duct provided above the paper transport path through which the paper is transported after passing through the fixing device; a second duct provided below the paper transport path through which the paper is transported after passing through the fixing device; An image forming apparatus comprising:

2. 2. The image forming apparatus according to claim 1, A suction amount adjusting unit is provided to adjust the amount of suction in the first duct and the second duct. An image forming apparatus comprising:

3. 3. The image forming apparatus according to claim 2, The suction amount adjusting unit changes the ratio of the suction amounts of the first duct and the second duct. An image forming apparatus comprising:

4. 3. The image forming apparatus according to claim 2, The suction amount adjustment unit sets the suction amounts in the first duct and the second duct based on the distance between sheets transported on the sheet transport path. An image forming apparatus comprising:

5. 5. The image forming apparatus according to claim 4, The suction amount adjustment unit increases the suction amount of the second duct as the distance between sheets transported on the sheet transport path becomes shorter. An image forming apparatus comprising:

6. 3. The image forming apparatus according to claim 2, The suction amount adjustment unit sets the suction amounts in the first duct and the second duct based on the width direction length of the paper transported on the paper transport path. An image forming apparatus comprising:

7. 3. The image forming apparatus according to claim 2, The suction amount adjustment unit sets the suction amounts in the first duct and the second duct based on the transport speed of the paper transported on the paper transport path. An image forming apparatus comprising:

8. 2. The image forming apparatus according to claim 1, A fan is provided which is connected to the exhaust ports of the first duct and the second duct. An image forming apparatus comprising:

9. 2. The image forming apparatus according to claim 1, The first duct is provided at the top of the housing. An image forming apparatus comprising:

10. 2. The image forming apparatus according to claim 1, The first duct and the second duct extend in the width direction of the paper sheet, and are longer than the maximum width of the paper sheet. An image forming apparatus comprising:

Images