Image forming apparatus

Abstract

The present invention provides an image forming apparatus equipped with a drainage mechanism that can reduce the intrusion of liquid into the inside of the apparatus through the ventilation opening. [Solution] The image forming apparatus 10 comprises an outer casing 12 that covers the periphery of the image forming apparatus 10, and a ventilation opening 22 provided in the outer casing 12 that allows air to circulate between the inner 14 and outer 13 of the image forming apparatus 10. The ventilation opening 22 has a predetermined shape that penetrates vertically through the outer surface of the outer casing 12, which is provided vertically. Below the ventilation opening 22, a water-repellent wall 28 is provided only on the inner surface of the outer casing 12, facing upward along the inner surface of the outer casing, and is higher than the outer surface of the outer casing of the ventilation opening 22.

Description

Technical Field

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[0001] The present disclosure relates to an image forming apparatus having a drainage mechanism.

Background Art

[0002] When liquid is spilled on an image forming apparatus, the liquid enters the apparatus through gaps in the exterior or louver holes. If the entered liquid reaches the active part of the primary circuit, there is a risk of a circuit short. A configuration for preventing such a situation is disclosed, for example, in Japanese Patent Application Laid-Open No. 2015-069029 (Patent Document 1). Patent Document 1 describes that in order to prevent water flowing from the upper part of the side wall from entering through the exhaust port of the fan, the exhaust port of the fan is provided with a plurality of louvers extending in the horizontal direction, and a lower wall portion provided on the lower surface side of the louver and protruding downward.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In a conventional image forming apparatus, a ventilation hole is provided which serves as an opening through which liquid can enter the back of the image forming apparatus. FIG. 20 is a perspective view showing the ventilation hole 112 which is an opening in the exterior 111 at the back of a conventional image forming apparatus 110. A perspective view of the ventilation hole 从外部看112 of the exterior 111 of the image forming apparatus 110 is shown in FIG. 21, and a perspective view of the ventilation hole 112 from the inside of the exterior 111 of the image forming apparatus 110 is shown in FIG. 22.

[0005] Figure 23 shows the detailed shape of the conventional ventilation opening 112 shown in Figures 21 and 22. On the left side of Figure 23 is a plan view of the ventilation opening 112 as seen from the outside of the exterior casing 111 (see Figure 20), to the right is a cross-sectional view of the ventilation opening 112, and at the bottom is a perspective view of the ventilation opening 112 as seen from the outside of the exterior casing 111. The conventional ventilation opening 112 was a roughly circular through-hole that penetrated the exterior casing 111 of the image forming apparatus 110.

[0006] Conventional image forming apparatuses 110 had a drainage mechanism (gutter shape or water receiving section) on the inner surface of the outer casing 111 to drain liquids that had entered the image forming apparatus 110 to the outside, thereby preventing water leakage into the image forming apparatus 110. However, this had the problem of allowing liquids to enter the image forming apparatus 110.

[0007] This disclosure is made to resolve the above-mentioned problems and aims to provide an image forming apparatus equipped with a drainage mechanism that can reduce the intrusion of liquid into the inside of the image forming apparatus from a ventilation opening provided in the image forming apparatus. [Means for solving the problem]

[0008] The image forming apparatus according to this disclosure comprises an exterior covering the periphery of the image forming apparatus, and a ventilation opening provided in the exterior covering for air circulation between the inside and outside of the image forming apparatus. The ventilation opening has a predetermined shape that penetrates vertically through the exterior surface of the exterior covering which is provided vertically, the opening of the ventilation opening on the outside of the image forming apparatus is larger than the opening on the inside, and a wall extending upward along the inner surface of the exterior covering is provided only on the inner surface of the exterior covering at the bottom of the ventilation opening.

[0009] Preferably, multiple ventilation openings are provided in parallel in the horizontal and vertical directions of the exterior.

[0010] More preferably, the top of the wall is provided with a projection extending across the entire top of the wall toward the outer surface of the exterior.

[0011] The outer surface of the wall may be composed of vertical surfaces.

[0012] The wall surface is a sloped surface that is inclined with respect to the vertical, and the uppermost part may be located closer to the outside of the exterior than the lowermost part.

[0013] The angle of the slope, which is inclined with respect to the vertical, should preferably be 45 degrees or less with respect to the vertical direction.

[0014] A concave groove may be provided directly above the ventilation opening, adjacent to the upper surface of the ventilation opening and open to the outside of the exterior.

[0015] A wall conforming to the shape of the upper surface of the ventilation opening may be provided between the upper surface of the ventilation opening and the concave groove.

[0016] The concave groove may be provided adjacent to the upper surface of the vent, following the shape of the upper surface of the vent.

[0017] The specified shape may be approximately circular or a regular polygon. [Effects of the Invention]

[0018] According to this disclosure, an image forming apparatus can be provided that prevents liquid from entering from the outside by providing a wall that faces upward along the inner surface of the outer casing only on the inner surface of the outer casing below a ventilation opening that could be a route for liquid to enter.

[0019] The aforementioned purposes, other purposes, features, and advantages of this disclosure will become even clearer from the detailed description of the embodiments described below with reference to the drawings. [Brief explanation of the drawing]

[0020] [Figure 1] This figure shows the rear view of an image forming apparatus equipped with a ventilation opening according to one embodiment of the present disclosure. [Figure 2] This is a magnified view of the area near the water intrusion prevention recess shown in Figure 1 and the ventilation opening. [Figure 3] Figure 2 is a perspective view from the outside of the image forming apparatus casing of the area near the water intrusion prevention recess and the ventilation opening. [Figure 4]It is a perspective view of a water injection test fluid analysis device. [Figure 5] It is a view of four different-shaped vents formed in the wall of the water injection test fluid analysis device as seen from the outside of the wall of the water injection test fluid analysis device. [Figure 6] It is a view showing the flow of water in the initial state when water is dropped from the water storage section onto the vent. [Figure 7] It is a view showing the flow of water after a certain period of time when water is dropped from the water storage section onto the vent. [Figure 8] It is a view showing a basic vent which is the basic structure of the vent according to the present disclosure. [Figure 9] It is a view showing a first vent according to the present disclosure. [Figure 10] It is a view showing a second vent according to the present disclosure. [Figure 11] It is a view showing a third vent according to the present disclosure. [Figure 12] It is a view showing each case where the angle of the concave groove provided above the vent is changed. [Figure 13] It is a view showing the state of water inflow as seen from the inside of the wall when water is dropped from above the concave grooves having the respective angles shown in FIG. 12. [Figure 14] It is a view showing the flow of water depending on the angle of the groove. [Figure 15] It is a view showing each groove when the depth of the concave groove is changed. [Figure 16] It is a view showing the state of water flowing from above as seen from the inside of the wall at each groove depth of FIG. 15. [Figure 17] It is a view showing the case where the basic vent shown in FIG. 8 is substantially circular. [Figure 18] It is a view showing the case where the vent is substantially regular polygon. [Figure 19] It is a view showing the case where the vent is substantially regular polygon. [Figure 20] It is a perspective view showing a ventilation opening which is an opening of the exterior at the back of a conventional image forming apparatus. [Figure 21] It is a perspective view of a conventional ventilation opening as seen from the outside of the exterior of the image forming apparatus. [Figure 22] This is a perspective view of a conventional ventilation opening, seen from the inside of the exterior of the image forming apparatus. [Figure 23] This diagram shows the detailed shape of a conventional ventilation opening. [Modes for carrying out the invention]

[0021] Hereinafter, one embodiment of the present disclosure will be described in detail with reference to the drawings. Figure 1 is a view showing the rear of an image forming apparatus 10 equipped with a ventilation opening according to one embodiment of the present disclosure, and is a view showing the portion corresponding to the rear of a conventional image forming apparatus 110 shown in Figure 20. Figure 2 is an enlarged view of the vicinity of the water intrusion prevention recess 15 and the ventilation opening 16 shown in Figure 1, and Figure 3 is a perspective view of the vicinity of the water intrusion prevention recess 15 and the ventilation opening 16 shown in Figure 2, as seen from the outside 13 of the exterior 12 of the image forming apparatus 10. Referring to Figures 1 to 3, the image forming apparatus 10 has an exterior 12 that covers the periphery of the image forming apparatus 10, and a water intrusion prevention recess 15 is provided in the upper right part of the rear of the exterior 12, and a ventilation opening 16, which is a through hole that allows air to pass between the outside 13 and inside 14 of the exterior 12 of the image forming apparatus 10, is provided below the recess 15.

[0022] [First Embodiment] The ventilation opening 16 has a predetermined shape (in this case, approximately circular) that penetrates vertically through the exterior surface of the exterior 12, which is provided in the vertical direction. Multiple ventilation openings 16 are provided in parallel in both the horizontal and vertical directions of the exterior 12.

[0023] In this disclosure, a water injection test fluid analysis was performed to analyze the intrusion of water from a ventilation port 16 provided on the back of the image forming apparatus 10. A perspective view of the water injection test fluid analysis apparatus used here is shown in Figure 4. Referring to Figure 4, the water injection test fluid analysis apparatus 17 includes a wall portion 20 having a plurality of ventilation ports 18 that mimic the ventilation port 16 of the image forming apparatus 10, and a water reservoir portion 19 that holds water and is provided above the wall portion 20 and above the plurality of ventilation ports 18. Hereinafter, the through-holes that allow air to pass through the image forming apparatus 10 will be referred to as ventilation ports 16, and the through-holes that mimic the ventilation port 16 of the water injection test fluid analysis apparatus 17 will be referred to as ventilation ports 18.

[0024] In this disclosure, the optimal shape of the ventilation port 16 of the image forming apparatus 10 is determined by fluid analysis using a water injection test, as will be explained later.

[0025] Referring to Figure 4, a water reservoir 19 is provided 100 mm above the vent 18. The water reservoir 19 is a rectangular parallelepiped, with dimensions of 30 mm in length (depth) x 20 mm in width (protrusion from the wall 20) x 220 mm in width (width of the multiple vents 18). Water is dropped from the water reservoir 19 down the wall 20 into the multiple vents 18 by gravity.

[0026] Here, four different shapes of vents 18 were prepared, and for each shape, water was lowered by gravity from the water reservoir 19 of the water injection test fluid analysis apparatus 17 shown in Figure 4, and the ingress of water into the vents 18 was observed.

[0027] The following describes the water intrusion situation in the vents 18, which have four different shapes.

[0028] Figure 5 is a perspective view of four different shaped vents 18 formed in the wall 20 of the water injection test fluid analysis apparatus 17, as seen from the outside of the wall 20 of the water injection test fluid analysis apparatus 17. As shown in Figure 5, four different shaped vents are provided adjacent to each other in the vertical direction: a conventional shaped vent 21 (indicated as Ref in the figure), a first vent 25 (indicated as S05 in the figure), a second vent 30 (indicated as S06 in the figure), and a third vent 34 (indicated as S08 in the figure).

[0029] Next, the details of each vent will be explained. Referring to Figure 5, the conventional vent 21 is a roughly circular through-hole. The first vent 25 has an elongated hole 25a on the outside that extends downwards compared to the conventional vent 21, with a concave groove 26 at its top. Inside, a closed section up to the position of the conventional vent 21 is provided as a wall 28, which is configured to return water entering from the outside and prevent it from entering the inside. In other words, the opening of the vent 21 on the outside of the image forming apparatus 10 is larger than the opening on the inside. Therefore, below, this wall (closed section) 28 may be referred to as a "water barrier". Thus, the first vent 25 may be described as having a water barrier 28.

[0030] The second vent 30 has almost the same shape as the first vent 25. The third vent 34, like the first and second vents 25 and 30, has a water barrier 35 on the inside up to the position of the conventional vent 21, but unlike these, the upper part of the third vent 34 does not have a concave groove.

[0031] Next, we will explain the water flow when water is poured from the water storage section 19 into these four vents. Figures 6 and 7 show the initial state (Figure 6) and the state after a certain period of time (Figure 7) of the water flow when water is poured from the water storage section 19 into these four vents 21, 25, 30, and 34. In the figures, the shaded areas indicate areas where the water flow or stagnation is large.

[0032] In Figures 6 and 7, from left to right, are the third vent 34, the second vent 30, the first vent 25, and the conventional vent 21, arranged in the reverse order of Figure 5. Also, in the figures, the left side is the inside of the wall 20, and the right side is the outside of the wall 20. First, let's explain Figure 6. Referring to the third vent 34 (S08) at the left end of Figure 6, there are three third vents 34 arranged vertically. An elongated hole 34a is provided on the outside of the wall 20, and a water barrier 35 is provided on the inside. Since water is falling from above, the amount of water flowing into the uppermost third vent 34 is greater than the amount of water flowing into the third vent 34 located below it.

[0033] Next, the second vent 30 (S06) will be explained. Here, the illustration of the second vent 30 is omitted, and only the water flow is shown, and even the water flow is shown only at the top, omitting the lower part. Referring to the second vent 30, here too, the amount of water flowing into the uppermost second vent 30 is greater than the amount of water flowing into the second vent 30 located below it. Also, in Figure 6, the amount of water flowing into the vent is reduced at the first vent 25 compared to the third vent 34.

[0034] Next, we will explain the first vent 25 (S05). Here again, the illustration of the first vent 25 is omitted, and only the water flow is shown, and even the water flow is shown only at the top, omitting the lower part. In the case of the first vent 25, the amount of water flowing into the uppermost first vent 25 is greater than the amount of water flowing into the first vent 25 located below it.

[0035] Next, we will describe the conventional shape of the vent 21. Here again, the illustration of the first vent is omitted, and only the water flow is shown, and even the water flow is shown only at the top, with the lower part omitted. As is clear from this diagram, in the conventional shape of the vent 21, a large amount of water flows into the machine from the initial stage.

[0036] Next, Figure 7 will be explained, which shows the state after a certain time T1 has elapsed from the state shown in Figure 6. In Figure 7, the contents shown are the same as in Figure 6, and from left to right they are the third vent 34, the second vent 30, the first vent 25, and the conventional vent 21. First, referring to the third vent (S08) on the left, this shows a state where three third vents 34 are lined up vertically. An elongated hole 34a is provided on the outside of the wall portion 20, and a water barrier 35 is provided on the inside. Since the water is falling from above, the amount of water flowing into the uppermost first vent 25 is greater than the amount of water flowing into the first vent 25 located below it, and since time has elapsed since Figure 6, the amount of water flowing in is also greater, but the inflow of water into the inside of the machine is prevented.

[0037] At the point shown in Figure 7, water ingress into the cabin is prevented. However, after a further time T2 has passed since the state shown in Figure 7, although not shown, a small amount of water has ingressed into the cabin. Water ingress into the cabin is confirmed, but compared to Ref, the amount of water ingress into the cabin has decreased, and the water ingress has been greatly improved.

[0038] Next, the second vent 30(S06) will be explained. Here again, the illustration of the second vent 30 is omitted, and only the water flow is shown, and even the water flow is shown only at the top, with the lower part omitted. Referring to the second vent 30(S06), here too, the amount of water flowing into the vent is greater for the uppermost second vent 30(S06) than for the second vent 30(S06) located below it. After a further time T2 has elapsed from the state in Figure 7, although not shown, no water has entered the interior of the machine, and the ingress of water into the interior of the machine is suppressed more than with the third vent 34(08).

[0039] Next, the first vent 25(S05) will be explained. In this case as well, the amount of water flowing into the vents is greater for the uppermost first vent 25(S05) than for the first vent 25(S05) located lower down. After a further time T2 has elapsed from the state shown in Figure 7, although not shown in the figure, no water has entered the inside of the machine.

[0040] Next, we will describe a conventional vent (Ref) 21. Here again, the illustration of the first vent 25 is omitted, and only the water flow is shown, and even the water flow is shown only at the top, with the lower part omitted. Here as well, in the conventional vent 21, a large amount of water flows into the inside of the wall 20 even after a certain period of time has elapsed.

[0041] From Figures 5 to 7, and the state after a further time T2 has elapsed from the state in Figure 7 (not shown), the following can be seen. First, in the case of the third vent 34, a water barrier is provided compared to the conventional shaped vent 21, so the intrusion of water into the machine can be greatly suppressed. Also, in the case of the first vent 25 and the second vent 30, concave grooves 26 and 31 are provided at the top, so the intrusion of water into the machine can be suppressed even more significantly than with the third vent 34.

[0042] In this example, the first vent 25 and the second vent 30 have similarly shaped water-repellent walls, and both the inner surface of the water-repellent wall and the outer surface of the exterior are provided vertically. However, the outer surface of the water-repellent wall may be sloped relative to the vertical, tilting from the inner surface 14 to the outer surface 13 of the exterior 12 as it goes upwards. In other words, the top of the water-repellent wall may be located closer to the outside of the exterior than the bottom. In this case, it is preferable that the slope relative to the vertical is 45 degrees or less.

[0043] Furthermore, although four different shapes of vents 21, 25, 30, and 34 are provided in multiples in the vertical direction here, when actually providing multiple vents 16 in parallel in the horizontal and vertical directions of the exterior 12 (see Figure 1), only one shape of vent from the four different shapes 21, 25, 30, and 34 should be used as the vents 16, and concave grooves 26 and 31 should be provided only along the top of the uppermost vent 16.

[0044] To increase the effective ventilation area through which air passes through the vents, they can be installed only at the top, or to greatly reduce water intrusion, recessed grooves can be installed at the top of all the vents.

[0045] Therefore, concave grooves are not provided above the ventilation openings 16 in any row other than the top row of the ventilation opening group in which multiple ventilation openings 16 are arranged in parallel.

[0046] Next, the detailed shape of the basic vent according to this disclosure will be described. Figure 8 is a diagram showing the basic vent, which is the basic structure of the vent according to this disclosure. Referring to Figure 8, the upper left of the figure shows a plan view of the basic vent 22 as seen from the outside of the wall 20 (see Figure 4), the right side shows a cross-sectional view of the basic vent 22, and the lower part shows a perspective view of the basic vent 22 as seen from the outside of the wall 20. In the cross-sectional view of the basic vent 22 on the right side of Figure 8, the left side is the machine side and the right side is the machine side. As shown in the plan view and cross-sectional view of Figure 8, a concave groove 23 of the same width and depth is provided only above the basic vent 22, which is a roughly circular through-hole as seen from the outside of the wall 20.

[0047] In other words, in the image forming apparatus 10 of this disclosure, a basic ventilation opening 22 as shown in Figure 8 and a concave groove 23 adjacent to its upper surface are provided as ventilation openings 16 on the outer surface 13 of the outer casing 12 shown in Figure 3.

[0048] Referring to the cross-sectional view in Figure 8, the dimensions of the basic vent 22 and the concave groove 23 are as follows: The diameter of the basic vent 22 is 3 mm. The width a of the concave groove 23 provided above the basic vent 22 is 0.5 mm, but 0.3 mm or more is preferable. If this width a is too small, the water intrusion prevention effect will be reduced. Increasing the thickness will not change the effect, but will also increase the area and make it look worse.

[0049] [Second Embodiment] The thickness b of the wall 24 between the basic vent 22 and the concave groove 23 that follows the shape of the upper surface of the vent provided above it is 0.2 mm, but preferably 0.5 mm or less. If the dimension of the wall 24 is large and the concave groove 23 is too far from the basic vent 22, the water intrusion prevention effect will be reduced. Conversely, if the dimension of the wall 24 is too thin, it may be impossible to process or it may break. Note that the wall 24 is not shown in Figure 5 shown earlier.

[0050] The depth c of the concave groove 23 will be described later. The position of the upper part of the basic ventilation opening 22 where this concave groove 23 is provided will also be described later.

[0051] The following describes a specific example of a ventilation opening based on the structure of the basic ventilation opening 22 shown in Figure 8. Figure 9 shows the first ventilation opening 25 according to this disclosure. Referring to Figure 9, the left side of the figure shows a plan view as seen from the outside of the wall portion 20, and the right side shows a cross-sectional view of the first ventilation opening 25. As shown in Figure 9, here, similar to Figure 8, a concave groove 26 of the same width and depth is provided only above the substantially circular first ventilation opening 25 as seen from the outside of the wall portion 20. The dimensions of the wall 27 between the first ventilation opening 25 and the concave groove 26 provided above it are the same as dimension b shown in the basic ventilation opening 22. In addition, the lower part of the outer wall portion 20 of the first ventilation opening 25 is an elongated hole 25a, and its inner end is closed to form a water return 28. Furthermore, a projection 28a that protrudes to the outside of the wall portion 20 is provided at the upper end of this water return 28.

[0052] Figure 10 shows the second vent 30 according to the present disclosure. Referring to Figure 10, the left side of the figure shows a plan view of the wall portion 20 as seen from the outside, and the right side shows a cross-sectional view of the second vent 30. As shown in Figure 10, the second vent 30, the concave groove 31, the wall 32, the water return 33, and the protruding portion 33a have the same shape as those provided in the first vent 25 shown in Figure 9.

[0053] Figure 11 shows the third vent 34. Referring to Figure 11, the left side of the figure shows a plan view of the wall 20 as seen from the outside, and the right side shows a cross-sectional view of the third vent 34. As shown in Figure 11, the third vent 34 is basically the same shape as the first and second vents 25 and 30 described above, but it does not have the concave groove shown in Figures 9 and 10. Here as well, the lower part of the outside of the wall 20 of the third vent 34 is an elongated hole 34a, and its inner end is closed to form a water barrier 35. In addition, a projection 35a facing outward from the wall 20 is provided at the upper end of this water barrier 35.

[0054] Next, the angle of the concave groove provided above the vent of the water injection test fluid analysis device 17 will be explained. Figure 12 shows the cases in which the angle of the concave groove provided above the vent is changed. From left to right, the figures show the conventional shape of the vent 21 (indicated as Ref in the figure), and the cases in which the angle of the concave groove is changed to 40°, 100°, 140°, and 192°. Note that all vents are straight through holes with a diameter of 3 mm, and only the conventional shape of the vent 21 does not have a concave groove.

[0055] Figure 13 shows the water inflow state as viewed from the inside of the wall 20 when water is dropped from above the concave grooves with the angles shown in Figure 12.

[0056] Referring to Figures 12 and 13, we first examine the effect of the concave groove. Comparing the conventional vent 21 shape with other vents, it can be seen that water intrusion is reduced in the vent with the concave groove.

[0057] Next, we consider the angle of the concave groove. As shown in Figure 13, simulations were performed with angles of 40°, 100°, 140°, and 192° between the ends of the arc-shaped concave groove. The results show that the water intrusion reduction effect is greatest for angles of 100°, 140°, 40°, and 192°. This is thought to be because if the angle of the concave groove is 40°, the angle is too small, making it easy for water to penetrate from areas not covered by the groove. Therefore, it is preferable that the angle between the ends of the concave groove along the upper surface of the vent is 100° or more (45° or more on each side with respect to the center of the concave groove).

[0058] Next, we will consider the water flow when the angle of the concave groove is large. Figure 14 shows the water flow depending on the groove angle, and the direction of water flow is shown by thick lines in the figure, from left to right, for the conventional shape of the vent 21 and when the angle of the concave groove is 40°, 100°, 140°, and 192°. Referring to Figure 14, it is thought that the radial velocity of the water decreases in the range exceeding 100°, making it easier for the water to enter the vent.

[0059] Next, we will explain the groove depth of the concave groove indicated by c in the cross-sectional view of Figure 8. Figure 15 shows the grooves when the depth of the concave groove is changed. In the figure, Ref is the conventional shape of the vent 21 with no groove, 0.15 is the case when the groove depth c is 0.15 mm, 0.30 is the case when the groove depth c is 0.3 mm, and 0.50 is the case when the groove depth c is 0.50 mm. In the figure, water is assumed to flow from above as indicated by the arrows. Figure 16 shows the view from the inside of the wall 20 with water flowing from above at each groove depth in Figure 15, and shows the degree of water penetration into the inside of the wall 20.

[0060] Referring to Figure 16, the depth c of the concave groove was 0.15 mm, which resulted in the least water intrusion, followed by 0.3 mm, while 0.5 mm was similar to that of a conventional design without a concave groove.

[0061] From the above, the optimal value for the depth c of the concave groove is 0.15 mm, preferably 0.1 mm or more, and it is considered that a depth in the range of 0.15 mm to 0.30 mm is effective in reducing water intrusion.

[0062] If the groove depth c is greater than 0.3 mm, water will have difficulty flowing through the concave groove, so the rate of fall will not decrease, and the effect of reducing water intrusion will be reduced.

[0063] Next, the shape of the vent and the shape of the concave groove provided thereon will be described. Figures 17 to 19 show the shape of the vent used in this disclosure and the shape of other concave grooves provided thereon. Figure 17 shows the case where the basic vent 22 shown in Figure 8 is approximately circular. Here, the upper side shows the case where concave grooves 38 of 90° each (totaling 180°) are provided on the upper half of the vent 25, and the lower side shows the case where concave grooves 39 of 70° each (totaling 140°) are provided on the upper side of the vent 25.

[0064] Figures 18 and 19 show the case where the vent is a roughly regular polygon. Figure 18 shows the case where the vent is a roughly square shape, in which a square vent 40 is placed on the left so that two of its sides are horizontal, and a straight, concave groove 41 longer than one side of the square is provided above the upper side, and a square vent 42 is placed on the right so that the intersection of its two sides is at the top, and a bent, straight, concave groove 43 longer than one side of the square is provided above the two upper sides.

[0065] Figure 19 shows a case where the vent is pentagonal or more. Here, on the left side, a roughly regular pentagonal vent 44 is placed so that its base is horizontal, and the top of the roughly regular pentagonal vent 44 has a bent, straight, concave groove 45 that is longer than one side of the pentagon above the two upper sides at the corners of the roughly regular pentagon. On the right side, a roughly regular hexagonal vent 46 is placed so that the intersection of its two sides is at the top, and a bent, straight, concave groove 47 that is longer than one side of the roughly regular hexagon is above the two upper sides.

[0066] Figures 17 to 19 show only the top row of a group of ventilation openings arranged in parallel. As shown in the figures, a concave groove is provided above the ventilation openings, but this groove is not provided above the ventilation openings in any row other than the top row of the group of ventilation openings arranged in parallel.

[0067] As described above, in this disclosure, the ventilation opening of the image forming apparatus was made into an optimal shape based on the results obtained from fluid analysis by water injection tests.

[0068] This disclosure can be implemented in various other forms without departing from its spirit or main features. Therefore, the embodiments described above are illustrative and should not be constrained. Any modifications or changes within the equivalent scope of the claims of this disclosure are within the scope of this disclosure. [Industrial applicability]

[0069] According to this disclosure, an image forming apparatus can be provided that can reduce the intrusion of liquid from the ventilation opening, and therefore is useful as an image forming apparatus. [Explanation of Symbols]

[0070] 10 Image forming apparatus 12 Exterior 13 Outside 14 Inside 15. Recess to prevent water intrusion 16 Ventilation hole 17. Fluid analysis device for water injection testing 18 Ventilation holes 19 Water storage section 20 Wall 21 Conventional vent shape 22 Basic ventilation openings 23, 26, 31, 38, 39 Concave grooves 24, 27, 32 Wall 25 First ventilation opening 25a,30a,34a long hole 28, 33, 35 Wall (Water-repellent) 28a, 33a, 35a protrusion 30. Second ventilation opening 34 Third vent 40,42 Square-shaped vents 44. A roughly regular pentagonal vent. 46. ​​A roughly hexagonal vent. 41, 43, 45, 47 Straight, concave grooves

Claims

1. An image forming apparatus comprising an outer casing covering the periphery of the image forming apparatus, and ventilation openings provided in the outer casing for ventilating air between the inside and outside of the image forming apparatus, The aforementioned ventilation opening has a predetermined shape that penetrates vertically through the outer surface of the outer casing, which is provided in the vertical direction. The outer opening of the ventilation port of the image forming apparatus is larger than the inner opening. An image forming apparatus, wherein below the ventilation opening, a wall is provided that extends upward along the inner surface of the exterior, only on the inner surface of the exterior.

2. The image forming apparatus according to claim 1, wherein the ventilation openings are provided in parallel in the horizontal and vertical directions of the exterior.

3. The image forming apparatus according to claim 1, wherein the uppermost part of the wall is provided with a projection extending outward from the exterior over the entire uppermost area of ​​the wall.

4. The image forming apparatus according to claim 1, wherein the outer surface of the wall is composed of a vertical surface.

5. The image forming apparatus according to claim 1, wherein the outer surface of the wall is an inclined surface with respect to the vertical, and the uppermost part is located closer to the outside of the exterior than the lowermost part.

6. The image forming apparatus according to claim 5, wherein the angle of the inclined surface relative to the vertical is 45 degrees or less with respect to the vertical direction.

7. The image forming apparatus according to claim 1, wherein a concave groove is provided directly above the ventilation opening, adjacent to the upper surface of the ventilation opening and open to the outside of the exterior.

8. The image forming apparatus according to claim 1, wherein a wall conforming to the shape of the upper surface of the ventilation opening is provided between the upper surface of the ventilation opening and the concave groove.

9. The image forming apparatus according to claim 8, wherein the concave groove is provided adjacent to the upper surface of the ventilation opening, following the shape of the upper surface of the ventilation opening.

10. The image forming apparatus according to claim 1, wherein the predetermined shape is substantially circular or a regular polygon.

Images