Sheet stacking apparatus and image forming apparatus

Abstract

To prevent air sent out from a blower from flowing into a device body through a sheet discharge port.SOLUTION: The image forming device is provided with a sheet loading part 134 capable of loading the sheet P delivered via a sheet delivery port H1, and an air blowing device 136 for blowing air to the sheet P delivered from the sheet delivery port H1 toward the sheet loading part 134. Then, a flexible sheet member 140 (opening / closing member) is provided which, when the sheet P is discharged from the sheet discharge port H1, opens the sheet discharge port H1 with respect to a region corresponding to the width-direction size of the sheet P and keeps the sheet discharge port H1 closed with respect to regions other than the region.SELECTED DRAWING: Figure 9

Description

[Technical Field]

[0001] The present invention relates to a sheet stacking device that stacks sheets discharged from a sheet discharge port, and to an image forming apparatus including the same, such as a copying machine, a printer, a facsimile machine, or a combination machine thereof. [Background technology]

[0002] Conventionally, sheet stacking devices installed in image forming apparatuses and the like have been known to be equipped with a blower device that blows air onto sheets discharged from the sheet discharge port of the apparatus main body (image forming apparatus main body) to cool them (see, for example, Patent Document 1).

[0003] On the other hand, Patent Document 2 discloses a technique of providing a shutter that uniformly opens and closes the entire sheet discharge port (discharge section) to prevent foreign matter from entering the inside of the image forming apparatus main body through the sheet discharge port. Summary of the Invention [Problem to be solved by the invention]

[0004] In the technology of Patent Document 1, air sent out from the air blower flows into the inside of the image forming apparatus body through the sheet discharge port, cooling parts that are not intended to be cooled. Furthermore, even if the shutter disclosed in Patent Document 2 is used, this problem cannot be solved because the shutter cannot close the sheet discharge outlet while a sheet is being discharged from the sheet discharge outlet.

[0005] This invention has been made to solve the above-mentioned problems, and aims to provide a sheet stacking device and an image forming device that are less likely to cause the problem of air blown out from the blower device flowing into the inside of the device body through the sheet discharge port. [Means for solving the problem]

[0006] The sheet stacking device of this invention comprises a sheet stacking section on which sheets discharged through a sheet discharge outlet can be stacked, an air blowing device that blows air onto sheets discharged from the sheet discharge outlet toward the sheet stacking section, and an opening / closing member that, when a sheet is discharged from the sheet discharge outlet, opens the sheet discharge outlet in an area corresponding to the widthwise size of the sheet and keeps the sheet discharge outlet closed outside that area. [Effects of the Invention]

[0007] According to the present invention, it is possible to provide a sheet stacking device and an image forming device that are less likely to experience the problem of air blown out from the blower device flowing into the inside of the device body through the sheet discharge port. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is an overall configuration diagram showing an image forming apparatus according to an embodiment of the present invention; [Figure 2] FIG. 1 is a perspective view showing an image forming apparatus. [Figure 3] FIG. [Figure 4] FIG. 2 is a view of the internal space of the image forming apparatus as seen from the left side. [Figure 5] FIG. 4 is a diagram showing the flow of air in the blower device. [Figure 6] 10 is a perspective view showing the second sheet placement portion and the air blower device from diagonally below. FIG. [Figure 7] FIG. 4 is a perspective view showing a second sheet placement section and an air blower device from diagonally above. [Figure 8] FIG. 2 is a diagram showing the main parts of the internal space of the image forming apparatus. [Figure 9] 1A is a diagram showing a state of a paper passing area of ​​a flexible sheet member when a sheet is discharged, and FIG. 1B is a diagram showing a state of a paper non-passing area of ​​the flexible sheet member when a sheet is discharged. [Figure 10] (A) A view of the flexible sheet member from the left side when no sheet is being ejected, and (B) A view of the flexible sheet member from the left side when a sheet is being ejected. [Figure 11] FIG. 4 is a schematic perspective view showing the flexible sheet member when a sheet is being discharged. [Figure 12] FIG. 10 is a diagram showing a flexible sheet member as a first modified example. [Figure 13] FIG. 10 is a diagram showing the main parts of the internal space of the image forming apparatus as a second modified example. [Figure 14] FIG. 11 is a diagram showing the main parts of the internal space of the image forming apparatus as a third modified example. [Figure 15] FIG. 10 is a diagram showing a flexible sheet member as a fourth modified example. [Figure 16] FIG. 13 is a diagram showing a flexible sheet member as a fifth modified example. [Figure 17] FIG. 13 is a diagram showing a flexible sheet member as a sixth modified example. [Figure 18] FIG. 13 is a diagram showing a flexible sheet member as a seventh modified example. [Figure 19] 19 is a diagram showing a main part of the space inside the body in which the flexible sheet member of FIG. 18 is installed. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In each drawing, the same or corresponding parts are designated by the same reference numerals, and redundant explanations will be appropriately simplified or omitted.

[0010] The overall configuration and operation of an image forming apparatus 1 according to this embodiment will be described with reference to FIGS. As shown in Figures 1 and 2, in the image forming apparatus 1 of this embodiment, below the document transport device 110 (and the document reading device 102) and above the image forming unit 115, a space W (internal space) is formed surrounded by a side protrusion 116 (also a side wall portion) and a rear protrusion 117 (also a rear wall portion). This space W (internal space) is a space in which sheets P (sheets P after image formation (printing)) discharged from the image forming apparatus 1 can be discharged and stacked, and is also a space in which the discharged and stacked sheets P can be removed. This space W (internal space) and its vicinity function as a sheet stacking device 200 (see FIG. 3).

[0011] The internal space W is formed with a first space W1 and a second space W2 separated above the first space W1 by a second sheet placement section 135 (reversal tray). The first space W1 is provided with a first sheet loading section 134 as a sheet loading section capable of loading printed sheets P, and the printed sheets P are stacked sequentially on the sheet loading surface 134a of the first sheet loading section 134. The second space W2 is a space into which the sheet P is temporarily discharged, mainly in double-sided printing mode, in order to invert the sheet P after the front side has been printed. In this embodiment, the second space W2 can also function as a space for loading the printed sheet P in a location different from the first sheet loading section 134, and in such a case, the printed sheets P are stacked one after another on the second sheet loading section 135 (inversion tray). In this embodiment, an air blower 136 for cooling the sheets P stacked on the first sheet stacking section 134 is provided in the internal space W, which will be described in detail later.

[0012] Referring to Figure 1, the image forming device 1 has an image forming unit 115 and main body feed trays 112, 113, etc., located below the internal space W (in the -Z direction), a lateral protrusion 116 located to the side of the internal space W (in the -X direction, on the right side of Figure 1), a rear protrusion 117 (see Figure 2) located at the rear side of the internal space W (in the +Y direction, on the rear side perpendicular to the paper surface of Figure 1), and a document transport device 110, a document reading device 102, etc., located above the internal space W. The image forming unit 115 includes a writing device 103, image creating units 104Y, 104M, 104C, and 104K, an intermediate transfer belt 178, a primary transfer roller 189, a fixing device 120, and the like. An operation display panel 149 (operation display unit) for displaying various information about the image forming apparatus 1 and inputting various commands is provided on the exterior of the image forming apparatus 1. The side of the operation display panel 149 that an operator such as a user faces directly and operates or views the display is the front side (near side) of the image forming apparatus 1. Therefore, the internal space W is open on the front side and the left side when viewed from the front of the image forming apparatus 1.

[0013] Hereinafter, the image forming operation (printing operation) in the image forming apparatus 1 will be described with reference to FIG. First, the document D is transported (fed) from the document table in the direction of the arrow in the drawing by the transport rollers of the document transport device 110, and passes over the document reading device 102. At this time, the document reading device 102 optically reads image information of the document D passing above. The optical image information read by the document reading device 102 is converted into an electrical signal and then transmitted to the writing device 103. Then, the writing device 103 emits laser light based on the image information of the electrical signal onto the photosensitive drums 105Y, 105M, 105C, and 105K for each color, thereby carrying out an exposure process. Then, a charging process, an exposure process, and a development process are performed on the photosensitive drums 105Y, 105M, 105C, and 105K of the image forming units 104Y, 104M, 104C, and 104K, respectively, and desired images are formed on the photosensitive drums 105Y, 105M, 105C, and 105K, respectively. Thereafter, the images formed on the photosensitive drums 105Y, 105M, 105C, and 105K are transferred onto the intermediate transfer belt 178 in a superimposed state as a color image. Furthermore, the color image formed on the intermediate transfer belt 178 is transferred, at a position facing the secondary transfer roller 189 (secondary transfer nip), onto the sheet P that is fed and conveyed from one of the two main body feed trays 112 and 113 to the sheet feeding path K0 by the feed roller 197. Thereafter, the sheet P onto which the color image has been transferred is conveyed to the position of the fixing device 120. Then, the color image transferred to the front surface is fixed onto the sheet P (a fixing process). Then, the sheet P (printed sheet P) after an image has been formed by the image forming section 115 passes through the first sheet discharge path K1 (sheet discharge path) of the lateral protrusion 116, and is discharged from the first sheet discharge outlet H1 (sheet discharge outlet) by the first discharge roller pair 131 (discharge roller pair), and is stacked on the first sheet loading section 134 (sheet loading section) in the first space W1.

[0014] When a "duplex printing mode" is selected, which prints on both sides (front and back sides) of the sheet P, the sheet P, after the fixing process on the front side has been completed, is guided to the second sheet discharge path K2 (sheet relay path) by the operation of the switching claw, rather than being discharged directly from the image forming apparatus 1 as in the "single-sided printing mode" described above. The sheet P guided to the second sheet discharge path K2 is then guided to the sheet reversal path K3. At this time, the rear end of the sheet P is sandwiched between the second discharge roller pair 132 (reversal roller pair), and the other portion is discharged from the second sheet discharge opening H2 into the second space W2. The sheet P is then switched back by the reverse rotation of the second discharge roller pair 132 and conveyed toward the duplex conveyance path K4. Then, the sheet P guided to the double-sided conveying path K4 is conveyed again toward the position of the secondary transfer nip (secondary transfer roller 189). Then, at the position of the secondary transfer nip, an image is formed (printed) on the back side of the sheet P by the same image forming process (image forming operation) as described above, and then the sheet P undergoes a fixing process in the fixing device 120, and is discharged from the first sheet discharge port H1 via the first sheet discharge path K1 into the first space W1, and is stacked on the first sheet loading section 134.

[0015] The characteristic configuration and operation of the image forming apparatus 1 according to this embodiment will be described in detail below. As previously explained using Figures 1 and 2, the image forming apparatus 1 is provided with an image forming section 115, a side protrusion 116, a rear protrusion 117, a first sheet placing section 134 as a sheet placing section, a first discharge roller pair 131 as a discharge roller pair, a second sheet placing section 135 (reversal tray), a second discharge roller pair 132 (reversal roller pair), a blower device 136, and the like. The image forming apparatus 1 in this embodiment is provided with a sheet stacking device 200 (see FIG. 3) for stacking sheets P discharged from the sheet discharge outlet H1 (first sheet discharge outlet).

[0016] The image forming section 115 is a section that forms an image on the sheet P. The first sheet placing section 134 as a sheet placing section is disposed above the image forming section 115 and is configured to be able to stack sheets P after images have been formed in the image forming section 115. In this embodiment, the sheet placing surface 134a of the sheet placing section 134 is formed as an inclined surface that slopes upward from the upstream side toward the downstream side in the sheet discharge direction (+X direction). Also, as shown in Fig. 4, the sheet placing surface 134a is formed in a convex shape so that the center in the width direction (±Y direction) is higher than both end portions. 1 to 4, etc., second sheet placing section 135 (reversal tray) is surrounded by lateral protrusion 116 and rear protrusion 117 above space W (first space W1) that functions as first sheet placing section 134. Also referring to FIGS. 6 and 7, second sheet placing section 135 in this embodiment is a tray-shaped member whose side closer to lateral protrusion 116 is curved into a curved surface.

[0017] 1 to 5, the lateral protrusion 116 protrudes upward from a lateral side (in the -X direction, on the right side in FIG. 1) of the image forming unit 115 (or the image forming apparatus 1) and is disposed adjacent to the first sheet placing unit 134 (and the second sheet placing unit 135). The lateral protrusion 116 is provided with a first sheet ejection path K1 as a sheet ejection path for transporting the sheet P after an image has been formed in the image forming unit 115, a first sheet ejection outlet H1 as a sheet ejection outlet for ejecting the sheet P toward the first sheet placing unit 134, a second sheet ejection path K2 capable of transporting the sheet P after an image has been formed in the image forming unit 115, and a second sheet ejection outlet H2 capable of ejecting the sheet P toward the second sheet placing unit 135. The positional relationship between the image forming unit 115 and the lateral protrusion 116 includes a positional relationship in which the image forming unit 115 and the lateral protrusion 116 at least partially overlap in the up-down direction at the end side (side side) in the width direction (X direction, left-right direction in FIG. 1) of the image forming apparatus. It also includes a positional relationship in which the image forming unit 115 and the lateral protrusion 116 are lined up on the left and right in the width direction of the image forming apparatus. The rear protrusion 117 is disposed so as to protrude upward from the rear side (+Y direction) of the image forming unit 115 (or the image forming apparatus 1) and be adjacent to the first sheet placing unit 134 (and the second sheet placing unit 135). The rear protrusion 117, together with the image forming unit 115 and the lateral protrusion 116, forms a space W (internal space) that functions as the first sheet placing unit 134 (and the second sheet placing unit 135). The positional relationship between image forming unit 115 and rear-side protrusion 117 includes a positional relationship in which image forming unit 115 and lateral protrusion 116 at least partially overlap in the vertical direction at the rear side in the depth direction of the image forming device (Y direction, the direction perpendicular to the paper surface of FIG. 1). It also includes a positional relationship in which image forming unit 115 and lateral protrusion 116 are lined up on the left and right in the depth direction of the image forming device.

[0018] 4, 5, etc., the air blower 136 (air blower unit) is arranged in the space W (internal space) so as to face the front side (-Y direction) of the rear-side protrusion 117. The air blower 136 takes in air from the side facing the rear-side protrusion 117 and exhausts it toward the sheets P being discharged from the first sheet discharge outlet H1 serving as a sheet discharge outlet toward the first sheet placing section 134 serving as a sheet placing section (including not only the sheets P being discharged but also the sheets P after being placed on the first sheet placing section 134). Specifically, as shown in Figure 5, in the blower device 136, the first air intake 136a1 and the intake fan 136x for taking in air from the side of the rear protrusion 117 are positioned on the rear side (+Y direction) away from the front side (-Y direction) which is the front side for the user.

[0019] Specifically, the intake fan 136x and the first intake port 136a1 (intake port) of the blower 136 are disposed closer to the front (-Y direction) than the rear-side protrusion 117 and further rearward (+Y direction) than the sheets P loaded on the first sheet loading section 134. Specifically, the blower 136 is screwed (fixed) to the second sheet loading section 135 at points A and B (see FIGS. 3 and 6). Also, referring to Figures 6, 7, etc., the blower device 136 is integrally installed below (-Z direction) and at the rear side (+Y direction) of the second sheet loading section 135 (reversal tray), and is configured to exhaust air from above toward the sheet P (and the sheet P on the first sheet loading section 134) discharged from the first sheet discharge outlet H1 toward the first sheet loading section 134.

[0020] By providing the air blower 136 in this manner, the sheets P discharged and placed on the first sheet placing section 134 are cooled, and therefore, compared to when this is not the case, the toner image on the sheets P acts as a binder, making it less likely that the sheets P stacked on the first sheet placing section 134 will stick together. Furthermore, since the blower device 136 in this embodiment is configured to mainly draw air from the rear side of the image forming apparatus 1 (since the intake fan 136x and the first air intake 136a1 are located at the rear side), problems such as the user accidentally touching the intake fan 136x or the user perceiving the operating sound of the intake fan 136x as noise are less likely to occur. In particular, in this embodiment, the blower device 136 is positioned in front of the rear protrusion 117, at the rear of the internal space W, making it even more difficult for the user to access the intake fan 136x, and also making it more difficult for the operating noise of the intake fan 136x to reach the front of the image forming apparatus 1 where the user is standing. Furthermore, in this embodiment, since the intake fan 136x is installed near the first intake port 136a1, the intake efficiency (amount of intake air) is high (large), and the cooling effect on the sheet P can be improved.

[0021] More specifically, with reference to FIGS. 3 to 7, the blower 136 is provided with a duct 136a, a first intake port 136a1, a second intake port 136a2, an intake fan 136x, an exhaust port 136a3, and the like. Duct 136a is formed with a first intake port 136a1, a second intake port 136a2, an exhaust port 136a3, and the like. First air intake port 136a1 is a main air intake port that opens at a position facing rear-side protrusion 117 with a gap δ (see FIGS. 4 and 5) therebetween and takes air into duct 136a from gap δ. In this embodiment, first air intake port 136a1 opens in a circular shape with a diameter substantially equal to the fan diameter of intake fan 136x and faces the vertical wall portion of rear-side protrusion 117 with a gap δ therebetween. The second air intake 136a2 is a secondary air intake that opens toward the side (+X direction) opposite the side where the lateral protrusion 116 is arranged in the internal space W (first space W1) and takes air into the inside of the duct 136a. In this embodiment, with reference to Figures 4 and 5, the second air intake 136a2 is a plurality of slits that open in a plane parallel to the side of the image forming apparatus main body 1 (the side of the main body cover on the right side) and prevents the user from accidentally inserting their fingers. The intake fan 136x is disposed so as to face the first intake port 136a1 on the near side (-Y direction). The intake fan 136x is a fan for sucking air from the first intake port 136a1 and the second intake port 136a2, and is either installed inside the duct 136a or sandwiched between multiple ducts 136a. The exhaust port 136a3 is an opening for discharging air drawn in by the intake fan 136x through the duct 136a. The portion of the duct 136a where the exhaust port 136a3 is formed is formed below the second sheet loading section 135 (reversal tray) so as to extend from the rear side (+Y direction) to the front side (-Y direction). A plurality of exhaust ports 136a3 are formed at intervals in the width direction (the vertical direction in FIG. 5) in order to cool the sheet P across the width direction. In the blower device 136 configured in this manner, air taken in from the outside flows in the duct 136a in the direction indicated by the arrow in FIG. 5, and is finally exhausted from the exhaust port 136a3 in the direction indicated by the arrow in FIG.

[0022] In this embodiment, it is preferable that the gap δ (the gap in the ±Y directions) between the first intake port 136a1 and the rear protrusion 117 described above is set to 2 mm or more. It is more preferable that the gap δ is set to approximately 2 to 10 mm. This is because, when the gap δ is 1.5 mm or more, the cooling performance for the sheet P is gradually exerted, and when the gap δ is 2 mm or more, the cooling performance for the sheet P is sufficiently exerted. Note that, if the gap δ exceeds 10 mm, the operating noise of the intake fan 136x gradually leaks out to the outside, so it is more preferable to set the upper limit of the gap δ to 10 mm.

[0023] Moreover, blower device 136 in this embodiment is configured so that the amount of air taken in from first air intake port 136a1 is greater than the amount of air taken in from second air intake port 136a2. The first air intake port 136a1 is provided near the air intake fan 136x, and therefore can ensure a larger amount of air intake than the second air intake port 136a2, which is located away from the air intake fan 136x. However, second air intake port 136a2 is located sufficiently far from sheet P (sheet P heated by fixing device 120) on first sheet loading section 134 and is located at a position where it can sufficiently take in outside air from image forming apparatus 1, making it easy to take in relatively low-temperature outside air. First air intake port 136a1 is located downstream of second air intake port 136a2 in the flow direction of the intake air. Therefore, inside duct 136a, the air taken in from first air intake port 136a1 is cooled by the air taken in from second air intake port 136a2, and the temperature of the air discharged from exhaust port 136a3 is lower than when air is taken in only from first air intake port 136a1, thereby improving the cooling performance for sheet P. In this embodiment, both the first air intake 136a1 and the second air intake 136a2 are positioned not directly above the sheets P stacked on the first sheet loading section 134. Therefore, compared to when the first and second air intakes 136a1, 136a2 are positioned directly above the sheets P, the problem of taking in some or all of the heat from the sheets P as it rises is reduced.

[0024] 3 and the like, in the blower device 136 of this embodiment, it is preferable that the positions of the first air intake 136a1 and the air intake fan 136x in the sheet discharge direction (±X direction) approximately coincide with the position of the inclined surface of the sheet loading surface 134a, as shown in FIG. By arranging them in this manner, it becomes possible to enlarge the first air intake 136a1 and the air intake fan 136x in terms of layout by the amount of the downwardly sloping surface on the sheet placing surface 134a, thereby improving the cooling performance of the blower device 136.

[0025] Furthermore, in this embodiment, the second sheet loading section 135 (to which the air blower 136 is integrated by screwing) is not tightly fixed to the image forming apparatus main body 1 by screwing, but is fixed relatively loosely (semi-fixed) by a method other than screwing. As a specific example, the portions R1 and R2 surrounded by dashed lines in Figure 3 are fixed positions, and the second sheet placing portion 135 can be removably held on the lateral protrusion 116 and the rear protrusion 117 with its insertion portion inserted into an insertion receiving portion formed on at least one of the lateral protrusion 116 and the rear protrusion 117. With this configuration, compared to when the second sheet placing section 135 is tightly fixed to the image forming apparatus main body 1, vibrations caused by the air blower 136 (intake fan 136x) during operation are less likely to be transmitted to the image forming apparatus main body 1 via the second sheet placing section 135. This reduces the problem of abnormal images such as banding caused by vibrations in the image forming section 115.

[0026] 3, in the image forming apparatus 1 of the present embodiment, a sheet detection sensor 133 serving as a detection means for detecting the presence or absence of a sheet P passing near the first sheet discharge outlet H1 (sheet discharge outlet) is installed in the lateral protrusion 116. This sheet detection sensor 133 (detection means) is a reflective photosensor that optically detects whether or not a sheet P is present at that position. When multiple sheets P are successively discharged from the first sheet discharge outlet H1, the intake fan 136x is controlled so that it starts operating after a first predetermined time T1 has elapsed since the leading edge of the first sheet P is detected by the sheet detection sensor 133 (detection means), and stops operating after a second predetermined time T2 has elapsed since the trailing edge of the last sheet P is detected by the sheet detection sensor 133. By controlling the intake fan 136x in this way, the device can save energy compared to when the intake fan 136x is constantly running. In this embodiment, the first and second predetermined times T1 and T2 are both set to 0 seconds, but the first and second predetermined times T1 and T2 can also be set to other times.

[0027] Hereinafter, further characteristic configurations and operations of the sheet stacking device 200 installed in the image forming apparatus 1 according to this embodiment will be described in detail. 1 to 3, the image forming apparatus 1 in this embodiment is provided with a first sheet placing section 134 as a sheet placing section capable of stacking sheets P discharged from the image forming apparatus main body through a first sheet discharge outlet H1 as a sheet discharge outlet, and an air blower 136 that blows air onto sheets P discharged from the first sheet discharge outlet H1 (sheet discharge outlet) toward the first sheet placing section 134 (sheet placing section). Also, a first discharge roller pair 131 as a discharge roller pair capable of clamping and conveying sheets P is provided at the first sheet discharge outlet H1. The sheet stacking device 200 is a device that functions as part of the image forming device 1 and is capable of stacking sheets P discharged from the first sheet discharge outlet H1, and is provided with a first sheet loading section 134 that can load sheets P discharged through the first sheet discharge outlet H1, and an air blower 136 that blows air onto sheets P discharged from the first sheet discharge outlet H1 toward the first sheet loading section 134.

[0028] 8 to 11, the sheet stacking device 200 (image forming apparatus 1) in this embodiment is provided with a flexible sheet member 140 as an opening / closing member. The flexible sheet member 140 functions as a cooling air inflow prevention means that prevents air (cooling air) sent out from the air blower 136 from flowing into the image forming apparatus 1 through the first sheet discharge opening H1. This flexible sheet member 140 (opening / closing member) completely closes (blocks) the first sheet discharge outlet H1 when a sheet P is not discharged from the first sheet discharge outlet H1 (sheet discharge outlet) (when a sheet is not being discharged), as shown in Figures 8 and 10(A). In contrast, when a sheet P is discharged from the first sheet discharge outlet H1 (sheet discharge outlet) (during sheet discharge), the flexible sheet member 140 (opening / closing member) opens (uncovers) the first sheet discharge outlet H1 in the area (paper passing area M) corresponding to the width size of the sheet P (the size in the ±Y direction, which is also the direction perpendicular to the discharge direction (+X direction) of the sheet P), as shown in Figures 9, 10(B), and 11, and keeps the first sheet discharge outlet H1 closed (covered) in areas other than that area (non-paper passing area N). The state in which the first sheet discharge outlet H1 (sheet discharge outlet) is closed means that, when viewed from the side (air blowing direction) of the air blowing device 136, the first sheet discharge outlet H1 (sheet discharge outlet) is shielded and is not directly hit by the air blown out from the air blowing device 136.

[0029] For more details, referring to Fig. 10 etc., flexible sheet member 140 as an opening / closing member has cuts 140b formed without gaps in the width direction (±Y direction). That is, flexible sheet member 140 is a blind-shaped (comb-like) member formed with a plurality of width-shaped members (15 width-shaped members in the example of Fig. 10). For simplicity, Fig. 10 illustrates cuts 140b as gaps (the same applies to Figs. 15 to 18 which will be described later as modified examples). The flexible sheet member 140 is cantilevered with its upper end positioned as a fixed end. Specifically, the flexible sheet member 140 has an adhesive portion 140a formed in its upper portion (a portion where the notch 140b is not formed), and the adhesive portion 140a is attached as a fixed end to the wall surface 116x' (116x) via double-sided tape or the like. In this embodiment, the wall surface 116x (an outer wall surface facing the internal space W) of the lateral protrusion 116 has a lower portion that functions as a positioning portion that determines the position of the rear end of the sheet P loaded on the first sheet loading portion 134, and an upper portion 116x' that protrudes slightly in the +X direction, to which the adhesive portion 140a of the flexible sheet member 140 is attached. The flexible sheet member 140 has flexibility that does not prevent the sheet P from being discharged from the first sheet discharge opening H1, and stiffness that does not cause the flexible sheet member 140 to flutter toward the position of the first discharge roller pair 131 and get caught in the air blown out from the air blower 136. The flexible sheet member 140 is also made of a low-friction material that reduces sliding resistance when it comes into contact with the sheet P.

[0030] In this embodiment, a flexible sheet member 140 made of PET (polyethylene terephthalate) with a thickness of about 0.05 mm is used. The width-like members divided in the width direction by the cuts 140b each have a length of about 5 mm in the width direction (±Y direction) and a length of about 35 mm in the ±Z direction. Furthermore, in this embodiment, the portion 116x' of the wall surface 116 to which the adhesive portion 140a of the flexible sheet member 140 is attached is formed to protrude in the +X direction, but the adhesive portion 140a of the flexible sheet member 140 may be attached to a wall surface 116 that is formed flat from bottom to top without protruding in this manner.

[0031] By placing the flexible sheet member 140 (opening / closing member) configured in this manner on the outside (the side facing the air blower 136) of the first discharge outlet H1 (first discharge roller pair 131), as shown in Figures 8 and 10(A), when a sheet is not being discharged, the air blown out from the air blower 136 does not directly hit the first discharge outlet H1 (first discharge roller pair 131), and is less likely to flow into the inside of the image forming apparatus main body 1 from the first discharge outlet H1. 9, 10(B), and 11, when a sheet is discharged, only the width-like members of the flexible sheet member 140 (the central seven width-like members in the example of FIG. 10(B)) corresponding to the sheet passage area M (see FIG. 10(B)) of the sheet P are pressed by the sheet P and are turned up so as not to interfere with the discharge of the sheet P. At this time, the air sent out from the blower device 136 is mainly blown onto the sheet P (because it is used to cool the sheet P), and therefore, very little of it flows into the image forming apparatus main body 1 from the first discharge port H1. Furthermore, the flexible sheet member 140 has width-like members (in the example of FIG. 10(B) there are eight width-like members in total, four on each end) that correspond to the non-paper passing area N of the sheet P (see FIG. 10(B)), and so are not pushed by the sheet P and are not rolled up, so that the air blown out from the blower device 136 does not flow into the inside of the image forming apparatus main body 1 from the non-paper passing area N at the first discharge outlet H1. Therefore, in the image forming apparatus 1 of the present embodiment, the air blown from the air blower 136 flows into the inside of the image forming apparatus main body 1 through the first sheet discharge port H1, which reduces the problem of cooling parts that are not intended to be cooled (for example, the fixing device 120). In addition, there is no need for complex control such as stopping the operation of the air blower 136 when no sheets are being discharged. In the image forming apparatus 1 of the present embodiment, the fixing device 120 is installed relatively close to the first sheet discharge port H1, and when cooling air flows in from the first sheet discharge port H1, the temperature detected by the temperature detection sensor that detects the temperature (fixing temperature) of the fixing roller of the fixing device 120 drops. When the temperature detected by the temperature detection sensor drops in this way, the fixing roller is overheated by a heater (installed in a hollow portion inside the fixing roller) whose output is controlled so that the detected temperature becomes the target fixing temperature, making it difficult to form a good fixed image. This is why the present invention is useful.

[0032] In order to achieve such an effect, in this embodiment, the flexible sheet member 140 is configured so that its widthwise range (±Y direction) either coincides with the widthwise range of the first sheet discharge outlet H1 or includes the widthwise range of the first sheet discharge outlet H1 and is slightly longer (see Figure 10).

[0033] Also, referring to FIG. 8, in this embodiment, the flexible sheet member 140 is set so that in the height direction (±Z direction), the position of its upper end is a predetermined height z1 above the position of the upper end of the first discharge roller pair 131 (discharge roller pair), and the position of its lower end is a predetermined height z2 below the position of the lower end of the first discharge roller pair 131. This makes it easier to achieve the above-mentioned effect (the effect of preventing the problem of air flowing into the image forming apparatus main body 1 through the first sheet discharge port H1). Also, by setting the position of the lower end (free end) of the flexible sheet member 140 lower than the position of the lower ends of the first discharge roller pair 131, the problem of the width-like member of the flexible sheet member 140 being caught in the first discharge roller pair 131 is less likely to occur.

[0034] In particular, referring to Figure 8, in this embodiment, the flexible sheet member 140 (when not discharging sheets) is set so that the position of its lower end (free end) is higher than the position (maximum stacking height) of the uppermost sheet P1 in the maximum number of sheets PT that can be stacked on the first sheet loading section 134. By configuring it in this manner, the flexible sheet member 140 prevents problems such as the sheets P that are stacked in an orderly manner on the sheet loading surface 134a of the first sheet loading section 134 becoming disorganized (misaligned), and problems such as a decrease in the stackability of the sheets P stacked on the sheet loading surface 134a.

[0035] <Variation 1> As shown in Fig. 12, in the image forming apparatus 1 of the first modification, the opening and closing member that opens and closes the first sheet discharge outlet H1 is not a single blind-shaped (comb-like) flexible sheet member 140 with multiple notches as shown in Fig. 10, but rather a plurality of flexible sheet members 140 (15 flexible sheet members 140 in the example of Fig. 12) that are arranged side by side without any gaps in the width direction. That is, the flexible sheet members 140 shown in Fig. 12 are each individually cut. Each of the multiple flexible sheet members 140 has an adhesive portion 140a formed on the upper part, and these adhesive portions 140a are adhered above the first discharge roller pair 131 (first sheet discharge outlet H1) on the wall surface 116x of the lateral protrusion 116. For simplicity, FIG. 12 shows adjacent flexible sheet members 140 with a gap between them. Furthermore, even when multiple flexible sheet members 140 configured in this manner are used as opening / closing members, the problem of air blown out from the blower device 136 flowing into the inside of the image forming apparatus main body 1 through the sheet discharge port H1 is less likely to occur. It is also possible to block the first sheet discharge opening H1 by combining multiple flexible sheet members 140 described in Modification 1 and one flexible sheet member 140 described using Fig. 10. Furthermore, it is also possible to block the first sheet discharge opening H1 by using multiple flexible sheet members 140 with the cuts 140b formed therein described using Fig. 10.

[0036] <Variation 2> As shown in Figure 13, the flexible sheet member 140 (opening / closing member) installed in the image forming apparatus 1 in variant example 2 is also cantilevered, with the upper end position as a fixed end and the lower end position as a free end, similar to that shown in Figure 8, etc. Here, the lower end (free end) of the flexible sheet member 140 in Modification 2 is curled toward the downstream side in the sheet discharge direction (+X direction). That is, a curled portion 140d is formed on the free end (lower end) of the flexible sheet member 140, where the lower end curls toward the side away from the first sheet discharge outlet H1. With this configuration, when the width-shaped member of the flexible sheet member 140 is turned up by the sheet P discharged from the first sheet discharge opening H1, the lower end (curl portion 140d) of the flexible sheet member 140 (width-shaped member) is less likely to get caught on the sheet P. The flexible sheet member 140 (when not discharging a sheet) is formed so that the position where curling begins downstream in the sheet discharge direction (+X direction) on the lower end side (the boundary between the straight portion and the curled portion 140d) is a certain distance z3 below the lower end of the first discharge roller pair 131. This is because if the position where the curl of the curled portion 140d begins is formed above the lower end of the first discharge roller pair 131, there is a possibility that the air blown out from the blower device 136 will flow into the inside of the image forming device 1 from the lower end of the first discharge roller pair 131. Furthermore, even when the flexible sheet member 140 configured in this manner (or the multiple flexible sheet members 140 described in variant example 1) is used as an opening / closing member, the problem of air blown out from the blower device 136 flowing into the inside of the image forming apparatus main body 1 through the sheet discharge port H1 is less likely to occur.

[0037] <Variation 3> As shown in FIG. 14, the image forming apparatus 1 in the third modification is provided with a regulating member 143 that regulates the flexible sheet member 140 from being wound around the first discharge roller pair 131 (discharge roller pair). In detail, the regulating member 143 is the upper portion 116x' of the wall surface 116x of the lateral protrusion 116, and is a portion formed in a tapered shape so that the amount of protrusion gradually increases from above to below in the +X direction, and the adhesive portion 140a of the flexible sheet member 140 is attached across the width. In other words, the regulating member 143 holds the flexible sheet member 140 in a bent position diagonally downward in the +X direction from above (holding it on the side away from the first discharge roller pair 131), thereby regulating the flexible sheet member 140 from being wound around the first discharge roller pair 131. In addition, since the regulating member 143 only needs to regulate the flexible sheet member 140 from being wound around the first pair of discharge rollers 131, it does not have to be formed in a tapered shape as described above, and may, for example, simply have a rectangular cross-section that ensures the opposing distance between the flexible sheet member 140 and the first pair of discharge rollers 131. Moreover, it is preferable that flexible sheet member 140 is configured so that the cutout 140b is not held by (does not come into contact with) regulating member 143 in order to ensure the length of the portion that functions as a width-like member. Furthermore, even when the flexible sheet member 140 configured in this manner (or the multiple flexible sheet members 140 described in variant example 1) is used as an opening / closing member, the problem of air blown out from the blower device 136 flowing into the inside of the image forming apparatus main body 1 through the sheet discharge port H1 is less likely to occur.

[0038] <Variation 4> 15, in the image forming apparatus 1 of the fourth modification, the flexible sheet member 140 (opening / closing member) has no notches 140b formed except at both ends in the region corresponding to the width direction size of the sheet P with the smallest width direction size (A5 portrait size in the example of FIG. 15) among the multiple width direction sizes of the sheets P that can be discharged. In other words, the width direction range of the width-like member 140m in the center of the flexible sheet member 140 is determined according to the smallest width direction size that can be passed through. By configuring in this way, the number of cuts 140b formed in flexible sheet member 140 can be reduced. In addition, when the multiple flexible sheet members 140 described in variant example 1 are used as opening / closing members, instead of multiple flexible sheet members 140 being arranged in the area corresponding to the widthwise size of the sheet P with the smallest widthwise size, a single flexible sheet member 140 that is wider than other parts is arranged. Furthermore, even when the flexible sheet member 140 configured in this manner (or the multiple flexible sheet members 140 described in variant example 1) is used as an opening / closing member, the problem of air blown out from the blower device 136 flowing into the inside of the image forming apparatus main body 1 through the sheet discharge port H1 is less likely to occur.

[0039] <Variation 5> 16, in the image forming apparatus 1 in the fifth modified example, the flexible sheet member 140 (opening / closing member) has notches 140b formed at both ends thereof to fit an area corresponding to sheets (A4 portrait size and A3 portrait size in the example of FIG. 16) having a width direction larger than the sheet P having the minimum width direction size (A5 portrait size in the example of FIG. 16) previously described with reference to FIG. 15. In other words, the flexible sheet member 140 also has notches 140b formed at positions corresponding to both ends thereof to fit an area corresponding to the sheet P having a width direction size larger than the sheet P having the minimum width direction size. 16, the flexible sheet member 140 is configured to be able to discharge (convey) sheets P of three sizes: A5 portrait size, A4 portrait size, and A3 portrait size. In the flexible sheet member 140, notches 140b are formed at positions corresponding to both ends of the width direction of the A5 portrait size, notches 140b are formed at positions corresponding to both ends of the width direction of the A4 portrait size, and notches 140b (which are shown as edge faces in the example of FIG. 16, but are also considered to be notches here) are formed at positions corresponding to both ends of the width direction of the A3 portrait size. In addition, when the multiple flexible sheet members 140 described in variant example 1 are used as opening and closing members, the flexible sheet members 140 will be arranged at both ends of the area corresponding to a sheet with a width larger than the smallest width of the sheet P. Furthermore, even when the flexible sheet member 140 configured in this manner (or the multiple flexible sheet members 140 described in variant example 1) is used as an opening / closing member, the problem of air blown out from the blower device 136 flowing into the inside of the image forming apparatus main body 1 through the sheet discharge port H1 is less likely to occur. In the example of Figure 16, for simplicity, we have explained a case where the device is configured to be able to discharge (convey) sheets P of three sizes, but the number of sizes is not limited to this, and the position and number of cuts 140b can be set according to the number of sizes.

[0040] <Variation 6> As shown in FIG. 17, in the image forming apparatus 1 of the sixth modification, a flexible sheet member 140 (opening / closing member) has two notches 140b formed therein. Even in this configuration, the problem of air sent out from the air blowing device 136 flowing into the inside of the image forming apparatus main body 1 through the sheet discharge port H1 is less likely to occur. In particular, as explained above with reference to FIG. 16, when the configuration is such that sheets P of two sizes can be discharged (conveyed), this effect is more easily exhibited.

[0041] <Variation 7> As shown in FIGS. 18 and 19, in the image forming apparatus 1 of the seventh modification, a flexible sheet member 140 (opening / closing member) is cantilevered with its lower end as a fixed end and its upper end as a free end. More specifically, the flexible sheet member 140 in the seventh modification is upside down compared to the one previously described with reference to Fig. 10 etc. The lower end (fixed end) of the flexible sheet member 140 is positioned below the lower end of the first discharge roller pair 131 by a distance z2, and the upper end (free end) is positioned above the upper end of the first discharge roller pair 131 by a distance z1. Furthermore, the flexible sheet member 140 in Modification 7 has an upper end (free end) curled toward the upstream side in the sheet discharge direction (-X direction). That is, a curled portion 140v is formed on the free end (upper end) of the flexible sheet member 140, where the upper end curls toward the first sheet discharge opening H1. With this configuration, the air (cooling air) blown from the air blower 136 from an obliquely upward direction relative to the first sheet discharge outlet H1 is less likely to flow into the image forming apparatus 1 from the first sheet discharge outlet H1. Moreover, the flexible sheet member 140 in the seventh modification has a rounded (or curved) upper end. That is, the curled portion 140d on the upper end side (free end side) of the flexible sheet member 140 has a rounded shape with a rounded tip (for example, a width-like member whose tip is bent inward to form a loop, a rounded member attached to the tip, or a chamfered tip). By giving the upper end of the flexible sheet member 140 a rounded (or curved) shape in this manner, when the width-like member of the flexible sheet member 140 is rolled up by the sheet P discharged from the first sheet discharge outlet H1, the upper end (curl portion 140v) of the flexible sheet member 140 (width-like member) is less likely to get caught on the sheet P. In the example of Figure 19, the adhesive portion 140a of the flexible sheet member 140 is configured to be installed on the wall surface 116 via a base 150 (which is an intermediary member that is attached to the wall surface 116 so as to protrude from the wall surface 116 in the +X direction), but the adhesive portion 140a of the flexible sheet member 140 may also be attached directly to the wall surface 116 without using the base 150. Furthermore, even when the flexible sheet member 140 configured in this manner (or the multiple flexible sheet members 140 described in variant example 1) is used as an opening / closing member, the problem of air blown out from the blower device 136 flowing into the inside of the image forming apparatus main body 1 through the sheet discharge port H1 is less likely to occur.

[0042] As described above, the sheet stacking device 200 (image forming apparatus 1) in this embodiment is provided with the sheet loading section 134 capable of loading sheets P discharged through the sheet discharge outlet H1, and the air blower 136 that blows air onto the sheets P discharged from the sheet discharge outlet H1 toward the sheet loading section 134. The flexible sheet member 140 (opening / closing member) is provided to open the sheet discharge outlet H1 to an area corresponding to the width direction size of the sheet P when the sheet P is discharged from the sheet discharge outlet H1 and keep the sheet discharge outlet H1 closed to areas other than that area when the sheet P is discharged from the sheet discharge outlet H1. This reduces the possibility of the air sent out from the air blower 136 flowing into the inside of the apparatus body via the sheet discharge port H1.

[0043] In this embodiment, the present invention is applied to a sheet stacking device 200 installed in a color image forming apparatus 1, but the present invention can naturally also be applied to a sheet stacking device installed in a monochrome image forming apparatus. Furthermore, in this embodiment, the present invention is applied to a sheet stacking device 200 installed in an electrophotographic image forming apparatus 1, but the application of the present invention is not limited to this, and the present invention can also be applied to a sheet stacking device installed in other types of image forming apparatus (for example, an inkjet type image forming apparatus, a stencil printing apparatus, etc.). Furthermore, in this embodiment, the present invention is applied to the sheet stacking device 200 as a part of the image forming apparatus 1, but the sheet stacking device to which the present invention is applied does not have to have an image forming function (image forming unit). For example, the present invention can also be applied to a sheet stacking device installed in a post-processing device (for example, a device that performs post-processing such as stacking, folding, binding, and punching on sheets discharged from the image forming apparatus after image formation) that is connected to the image forming apparatus and configures an image forming system together with the image forming apparatus. Even in such cases, the same effects as those of this embodiment can be obtained.

[0044] It is to be noted that the present invention is not limited to the present embodiment, and it is clear that the present embodiment can be appropriately modified within the scope of the technical concept of the present invention in addition to the modifications suggested in the present embodiment. Furthermore, the number, position, shape, etc. of the components are not limited to the present embodiment, and the number, position, shape, etc. of the components can be any number, position, shape, etc. that is suitable for implementing the present invention.

[0045] In this specification, directions (sides) and surfaces such as "rear side," "side," "near side," and "rear" refer to the direction (side) that a user or other worker faces when performing normal operations on the image forming apparatus, defined as "near side" or "front." [Explanation of symbols]

[0046] 1. Image forming apparatus (image forming apparatus main body), 115 image forming unit, 116 Lateral projection; 116x, 116x´ wall, 117 Back protrusion, 131 first discharge roller pair (discharge roller pair), 134 first sheet placement section (sheet placement section), 134a sheet placement surface; 136 Blower (blower unit), 140 flexible sheet member (opening / closing member), 140a Adhesive part (fixed end), 140b cut, 140d curled part (bottom end), 140v curled part (rounded part, upper end), 143 Regulatory Members, 200 sheet stacking device, K1 First discharge route (discharge route), M paper passing area, N non-paper passing area, H1 1st discharge port (discharge port), W space (body space), P sheet (recording medium), P1 top seat, PT sheet stack.

[0047] The present invention can also be embodied in a combination of Supplementary Notes 1 to 14, for example, as follows. (Appendix 1) a sheet placement section capable of stacking sheets discharged through a sheet discharge port; a blower that blows air onto the sheets discharged from the sheet discharge port toward the sheet placement unit; an opening / closing member that, when a sheet is discharged from the sheet discharge outlet, opens the sheet discharge outlet in an area corresponding to a width direction size of the sheet and keeps the sheet discharge outlet closed in areas other than the area; A sheet stacking device comprising: (Appendix 2) 2. The sheet stacking device according to claim 1, wherein the opening / closing member entirely closes the sheet discharge outlet when no sheets are discharged from the sheet discharge outlet. (Appendix 3) The sheet stacking device according to claim 1 or 2, wherein the opening / closing member is a flexible sheet member having a notch formed in the width direction, or a plurality of flexible sheet members arranged side by side in the width direction. (Appendix 4) a pair of discharge rollers that are installed at the sheet discharge port and can hold and transport the sheet; The sheet stacking device described in Appendix 3 is characterized in that the flexible sheet member has an upper end positioned above the upper end position of the pair of discharge rollers, a lower end positioned below the lower end position of the pair of discharge rollers, and is cantilever-supported with the upper or lower end position as a fixed end. (Appendix 5) The sheet stacking device described in Appendix 3 or Appendix 4 is characterized in that the flexible sheet member is cantilevered with its upper end as a fixed end and its lower end as a free end, and the lower end side is curled downstream in the sheet discharge direction. (Appendix 6) 6. The sheet stacking device according to claim 5, wherein the flexible sheet member has a position at which curling begins downstream in the sheet discharge direction on the side of the lower end thereof, which is below the lower end of the pair of discharge rollers. (Appendix 7) The sheet stacking device described in Appendix 3 or Appendix 4 is characterized in that the flexible sheet member is cantilevered with its lower end position as a fixed end and its upper end position as a free end, and the upper end side is curled toward the upstream side in the sheet discharge direction. (Appendix 8) 8. The sheet stacking device according to claim 7, wherein the upper end of the flexible sheet member is rounded or curved. (Appendix 9) A sheet stacking device described in any one of Appendix 3 to Appendix 8, characterized in that the position of the lower end of the flexible sheet member is higher than the position of the uppermost sheet in a stack of sheets with the maximum number of sheets that can be stacked on the sheet stacking section. (Appendix 10) 10. The sheet stacking device according to any one of claims 4 to 9, further comprising a regulating member that regulates the flexible sheet member from being wound into the pair of discharge rollers. (Appendix 11) A sheet stacking device as described in any one of Appendix 3 to Appendix 10, characterized in that in an area corresponding to the width size of a sheet with the smallest width size among multiple width sizes that can be discharged, either the notch is not formed in the flexible sheet member or a single flexible sheet member is placed. (Appendix 12) The sheet stacking device described in Appendix 11 is characterized in that the flexible sheet member also has the notches formed at positions corresponding to both ends of an area corresponding to sheets with a width size larger than the smallest width size, or flexible sheet members are arranged at both ends of the area. (Appendix 13) an image forming unit that forms an image on the sheet; A sheet stacking device according to any one of Supplementary Note 1 to Supplementary Note 12; An image forming apparatus comprising: (Appendix 14) the sheet placement unit disposed above the image forming unit; a lateral protrusion portion that protrudes upward from a lateral side of the image forming portion and is disposed adjacent to the sheet stacking portion, and that is provided with a sheet discharge path for conveying a sheet after an image is formed in the image forming portion, and the sheet discharge outlet; a rear-side protruding portion that protrudes upward from a rear side of the image forming portion and is disposed adjacent to the sheet stacking portion, and that forms a space together with the image forming portion and the side protruding portion; the air blower is disposed in the space so as to face the rear-side protrusion on the front side, and exhausts air taken in from the side facing the rear-side protrusion toward the sheets discharged from the sheet discharge port toward the sheet placement section; 14. The image forming apparatus according to claim 13, comprising: [Prior art documents] [Patent documents]

[0048] [Patent Document 1] Patent No. 6035213 [Patent Document 2] Japanese Patent Application Laid-Open No. 2008-213970

Claims

1. a sheet placement section capable of stacking sheets discharged through a sheet discharge port; a blower that blows air onto the sheets discharged from the sheet discharge port toward the sheet placement unit; an opening / closing member that, when a sheet is discharged from the sheet discharge outlet, opens the sheet discharge outlet in an area corresponding to a width direction size of the sheet and keeps the sheet discharge outlet closed in areas other than the area; A sheet stacking device comprising:

2. 2. The sheet stacking device according to claim 1, wherein the opening / closing member completely closes the sheet discharge opening when no sheets are discharged from the sheet discharge opening.

3. 2. The sheet stacking device according to claim 1, wherein the opening / closing member is a flexible sheet member having a notch formed in the width direction, or a plurality of flexible sheet members arranged side by side in the width direction.

4. a pair of discharge rollers that are installed at the sheet discharge port and are capable of nipping and conveying a sheet; The sheet stacking device according to claim 3, characterized in that the flexible sheet member has an upper end positioned above the upper end position of the pair of discharge rollers, a lower end positioned below the lower end position of the pair of discharge rollers, and is cantilever-supported with the upper or lower end position as a fixed end.

5. 5. The sheet stacking device according to claim 4, wherein the flexible sheet member is cantilevered with its upper end as a fixed end and its lower end as a free end, and the lower end side is curled downstream in the sheet discharge direction.

6. 6. The sheet stacking device according to claim 5, wherein the position where the curl of the flexible sheet member starts downstream in the sheet discharge direction on the side of the lower end is below the lower ends of the pair of discharge rollers.

7. 5. The sheet stacking device according to claim 4, wherein the flexible sheet member is cantilevered with its lower end positioned as a fixed end and its upper end positioned as a free end, and the upper end side is curled toward the upstream side in the sheet discharge direction.

8. 8. The sheet stacking device according to claim 7, wherein the upper end of the flexible sheet member is rounded or curved.

9. 5. The sheet stacking device according to claim 4, wherein the lower end of the flexible sheet member is positioned above the position of the uppermost sheet in a stack of the maximum number of sheets that can be stacked on the sheet stacking section.

10. 5. The sheet stacking device according to claim 4, further comprising a restricting member for restricting the flexible sheet member from being wound around the pair of discharge rollers.

11. A sheet stacking device as described in claim 3, characterized in that in the area corresponding to the width size of the smallest width size sheet among the multiple width sizes that can be discharged, either the notch is not formed in the flexible sheet member or a single flexible sheet member is placed.

12. The sheet stacking device of claim 11, characterized in that the flexible sheet member also has the notches formed at positions corresponding to both ends of an area corresponding to sheets with a width larger than the smallest width, or the flexible sheet member is positioned at both ends of the area.

13. an image forming unit that forms an image on the sheet; The sheet stacking device according to claim 1 ; An image forming apparatus comprising:

14. the sheet placement unit disposed above the image forming unit; a lateral protrusion portion that protrudes upward from a lateral side of the image forming portion and is disposed adjacent to the sheet stacking portion, and that is provided with a sheet discharge path for conveying a sheet after an image is formed in the image forming portion, and the sheet discharge outlet; a rear-side protruding portion that protrudes upward from a rear side of the image forming portion and is disposed adjacent to the sheet stacking portion, and that forms a space together with the image forming portion and the side protruding portion; the air blower is disposed in the space so as to face the rear-side protrusion on the front side, and exhausts air taken in from the side facing the rear-side protrusion toward the sheets discharged from the sheet discharge port toward the sheet placement section; 14. The image forming apparatus according to claim 13, further comprising:

Images