Image forming device

Abstract

An image forming apparatus is provided with a drainage mechanism capable of reducing the intrusion of liquid into the inside of the apparatus through a ventilation hole. [Solution] Image forming device 10 includes exterior 12 that covers the periphery of image forming device 10, and ventilation opening 22 that is provided in exterior 12 and that ventilates air between inside 14 and outside 13 of image forming device 10. Ventilation opening 22 has a predetermined shape that penetrates vertically through the exterior surface of exterior 12 that is provided vertically, and directly above ventilation opening 22 on the surface of exterior 13 of the image forming device, a concave groove 23 that is adjacent to the upper surface of ventilation opening 22 and is open toward the outside of exterior 12 is provided.

Description

[Technical Field]

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

[0002] If liquid is spilled on an image forming apparatus, the liquid will seep into the interior of the apparatus through gaps in the exterior or through louver holes. If the intruding liquid reaches a live part of the primary circuit, it may cause a short circuit. 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 a configuration in which a fan exhaust port is provided with multiple louvers extending horizontally and a bottom wall portion provided on the underside of the louvers and protruding downward, in order to prevent water flowing from the upper part of the side wall from entering through the fan exhaust port. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-069029 Summary of the Invention [Problem to be solved by the invention]

[0004] Conventional image forming apparatuses are provided with a ventilation hole on the back surface of the image forming apparatus, which serves as an opening through which liquid can seep in. Fig. 20 is a perspective view showing ventilation hole 112, which serves as an opening in exterior casing 111 on the back surface of conventional image forming apparatus 110. Fig. 21 shows a perspective view of ventilation hole 112 as seen from the outside of exterior casing 111 of image forming apparatus 110, and Fig. 22 shows a perspective view of ventilation hole 112 as seen from the inside of exterior casing 111 of image forming apparatus 110.

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

[0006] In conventional image forming devices 110, a drainage mechanism (a gutter-shaped or water-receiving portion) was provided on the inner surface of exterior casing 111, which prevented liquid that had entered the image forming device 110 from leaking into the image forming device 110 by draining it to the outside. However, this still caused a problem in that it allowed liquid to enter the image forming device 110.

[0007] The present disclosure has been made to solve 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 image forming apparatus through ventilation holes provided in the image forming apparatus. [Means for solving the problem]

[0008] The image forming apparatus according to this disclosure includes an exterior that covers the periphery of the image forming apparatus, and a ventilation opening provided in the exterior that ventilates air 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 that is provided vertically, and a concave groove that is adjacent to the upper surface of the ventilation opening and is open toward the outside of the exterior is provided directly above the ventilation opening on the outer surface of the image forming apparatus of the exterior.

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

[0010] More preferably, a wall is provided between the upper surface of the vent hole and the concave groove, the wall conforming to the shape of the upper surface of the vent hole.

[0011] The concave groove is preferably provided adjacent to the upper surface of the vent opening along the shape of the upper surface of the vent opening.

[0012] The predetermined shape may be a substantially circular shape or a substantially regular polygonal shape.

[0013] The angle between both ends of the concave groove is preferably 45 degrees or more on either side of the center of the concave groove along the upper surface of the ventilation opening.

[0014] The top of the vent may be at a corner of a substantially regular polygon.

[0015] A concave groove is provided on the vents in the top row of a group of vents in which a plurality of vents are arranged in parallel, and no concave groove may be provided on the vents other than those in the top row of the group of vents in which a plurality of vents are arranged in parallel.

[0016] A concave groove may be provided on all of the vent holes in a group of vent holes in which a plurality of vent holes are arranged in parallel. [Effects of the Invention]

[0017] According to the present disclosure, by providing a concave groove directly above a ventilation hole that can serve as a path for liquid to enter, the force of liquid entering the ventilation hole can be weakened, thereby providing an image forming device that can reduce the intrusion of liquid through the ventilation hole.

[0018] The above and other objects, features, and advantages of the present disclosure will become more apparent from the following detailed description of the embodiments, which proceeds with reference to the drawings. [Brief explanation of the drawings]

[0019] [Figure 1] 1 is a diagram showing a rear view of an image forming apparatus equipped with a ventilation opening according to an embodiment of the present disclosure. [Figure 2] 2 is an enlarged view of the vicinity of the water intrusion prevention recess and the ventilation opening shown in FIG. 1. FIG. [Figure 3] 3 is a perspective view of the area near the water intrusion prevention recess and the ventilation hole shown in FIG. 2, viewed from the outside of the exterior of the image forming apparatus. FIG. [Figure 4] FIG. 1 is a perspective view of a water injection test fluid analysis device. [Figure 5]FIG. 10 is a view of four differently shaped vent holes formed in the wall of the water injection test fluid analysis device, as viewed from the outside of the wall of the water injection test fluid analysis device. [Figure 6] 10A and 10B are diagrams illustrating the flow of water in the initial state when water is allowed to fall from the water reservoir toward the vent. [Figure 7] 10A and 10B are diagrams showing the flow of water after a certain time has elapsed when water is allowed to fall from a water reservoir toward an air vent. [Figure 8] 1 is a diagram showing a basic vent, which is the basic structure of the vent according to the present disclosure. FIG. [Figure 9] FIG. 10 illustrates a first vent according to the present disclosure. [Figure 10] FIG. 10 illustrates a second vent according to the present disclosure. [Figure 11] FIG. 10 illustrates a third vent according to the present disclosure. [Figure 12] 10A and 10B are diagrams showing various cases where the angle of the concave groove provided above the ventilation opening is changed. [Figure 13] 13A and 13B are diagrams showing the inflow of water when water is dropped from above the recessed grooves having the angles shown in FIG. 12, as viewed from the inside of the wall portion. [Figure 14] FIG. 10 is a diagram showing the flow of water depending on the angle of the groove. [Figure 15] 10A and 10B are diagrams showing grooves when the depth of the concave grooves is changed. [Figure 16] 16A and 16B are diagrams showing the state in which water is allowed to flow from above, as viewed from the inside of the wall portion, for each groove depth in FIG. 15. [Figure 17] FIG. 9 is a diagram showing the basic vent hole shown in FIG. 8 in a substantially circular shape. [Figure 18] FIG. 10 is a diagram showing a case where the ventilation opening is a substantially regular polygon. [Figure 19] FIG. 10 is a diagram showing a case where the ventilation opening is a substantially regular polygon. [Figure 20] FIG. 10 is a perspective view showing a ventilation hole serving as an opening in the exterior of a conventional image forming apparatus on the rear side. [Figure 21] FIG. 10 is a perspective view of a conventional ventilation opening as seen from outside the exterior of an image forming apparatus. [Figure 22]FIG. 10 is a perspective view of a conventional ventilation opening as seen from inside the exterior of an image forming apparatus. [Figure 23] FIG. 10 is a diagram showing a detailed shape of a conventional ventilation opening. DETAILED DESCRIPTION OF THE INVENTION

[0020] An embodiment of the present disclosure will be described in detail below with reference to the drawings. FIG. 1 is a diagram showing the back of an image forming apparatus 10 equipped with a ventilation hole according to an embodiment of the present disclosure, and is a diagram showing a portion corresponding to the back of a conventional image forming apparatus 110 shown in FIG. 20. FIG. 2 is an enlarged view of the vicinity of the water intrusion prevention recess 15 and the ventilation hole 16 shown in FIG. 1, and FIG. 3 is a perspective view of the vicinity of the water intrusion prevention recess 15 and the ventilation hole 16 shown in FIG. 2, as viewed from the outside 13 of the exterior 12 of the image forming apparatus 10. Referring to FIGS. 1 to 3, the image forming apparatus 10 has an exterior 12 that covers the periphery of the image forming apparatus 10, and the exterior 12 has the water intrusion prevention recess 15 in the upper right portion of the back of the exterior 12, and the ventilation hole 16, which is a through-hole provided below the recess 15, allows air to circulate between the outside 13 and the inside 14 of the exterior 12 of the image forming apparatus 10.

[0021] [First embodiment] The ventilation openings 16 have a predetermined shape (here, substantially circular) and penetrate vertically through the exterior surface of the vertically disposed exterior casing 12. A plurality of ventilation openings 16 are provided in parallel in the horizontal and vertical directions of the exterior casing 12.

[0022] In the present disclosure, a water injection test fluid analysis was performed to analyze water intrusion through ventilation holes 16 provided on the rear surface of image forming apparatus 10. A perspective view of the water injection test fluid analysis device used here is shown in FIG. 4. Referring to FIG. 4, water injection test fluid analysis device 17 includes a wall portion 20 having a plurality of ventilation holes 18 that mimic the ventilation holes 16 of image forming apparatus 10, and a water storage portion 19 that holds water and is provided above wall portion 20 and above the plurality of ventilation holes 18. Hereinafter, the through holes that ventilate air in image forming apparatus 10 will be referred to as ventilation holes 16, and the through holes that mimic the ventilation holes 16 of water injection test fluid analysis device 17 will be referred to as ventilation holes 18.

[0023] In the present disclosure, the optimum shape of the ventilation opening 16 of the image forming apparatus 10 is identified by fluid analysis using a water injection test, as will be described later.

[0024] Referring to Figure 4, a water storage section 19 is provided 100 mm above the air vent 18, and the water storage section 19 is a rectangular parallelepiped, with dimensions of 30 mm in length (depth) x 20 mm in width (protrusion dimension from wall section 20) x 220 mm in width (width of multiple air vents 18), and water falls from the water storage section 19 along the wall section 20 by gravity into the multiple air vents 18.

[0025] Here, four shapes of vent 18 were prepared, and for each, water was allowed to fall by gravity from the water reservoir 19 of the water injection test fluid analysis device 17 in Figure 4, and the infiltration of water into vent 18 was observed.

[0026] The following describes how water infiltrates into ventilation holes 18 having four different shapes.

[0027] 5 is a perspective view of four differently shaped vents 18 formed in a wall 20 of the water injection test fluid analysis device 17, as viewed from the outside of the wall 20 of the water injection test fluid analysis device 17. As shown in FIG. 5, the four differently shaped vents are a conventionally shaped vent 21 (indicated by Ref in the figure), a first vent 25 (indicated by S05 in the figure), a second vent 30 (indicated by S06 in the figure), and a third vent 34 (indicated by S08 in the figure), which are provided adjacent to each other in the vertical direction.

[0028] Next, the details of each vent will be described. Referring to FIG. 5, the conventionally shaped vent 21 is a substantially circular through-hole. The first vent 25 has a downwardly elongated hole 25a on the outside compared to the conventionally shaped vent 21, a concave groove 26 provided at the top, and a closed portion provided on the inside up to the position of the conventionally shaped vent 21, which is configured to return water that enters from the outside and prevent it from entering the inside. Therefore, hereinafter, this closed portion will be referred to as the "water return." Accordingly, the first vent 25 is provided with a water return 28.

[0029] The second ventilation port 30 has almost the same shape as the first ventilation port 25. Like the first and second ventilation ports 25, 30, the third ventilation port 34 has a water return 35 provided on the inside up to the position of the conventionally shaped ventilation port 21, but unlike these, the third ventilation port 34 does not have a concave groove provided in the upper part.

[0030] Next, we will explain the flow of water when water is allowed to drop from the water storage section 19 to these four vents. Figures 6 and 7 are diagrams showing the initial state (Figure 6) and the state after a certain time has passed (Figure 7) of the water flow when water is allowed to drop from the water storage section 19 to these four vents 21, 25, 30, and 34, and in the figures, the shaded areas are areas where water flows or stagnates significantly.

[0031] 6 and 7, from the left end, there are the third vent 34, the second vent 30, the first vent 25, and the conventionally shaped vent 21, which are arranged in the reverse order from FIG. 5. In addition, in the figures, the left side is the inside of the wall portion 20, and the right side is the outside of the wall portion 20. First, FIG. 6 will be described. Referring to the third vent 34 (S08) at the left end of FIG. 6, three third vents 34 are lined up vertically. A long hole 34a is provided on the outside of the wall portion 20, and a water return 35 is provided on the inside. Because water falls from above, the amount of water flowing into the top third vent 34 is greater than the amount of water flowing into the third vents 34 located below.

[0032] Next, the second vent 30 (S06) will be described. Here, the second vent 30 is not shown and only the water flow is shown, and only the topmost water flow is shown, omitting the lower water flow. Referring to the second vent 30, the amount of water flowing into the topmost second vent 30 is also greater than the amount of water flowing into the second vent 30 located below. Also, in FIG. 6, the amount of water flowing into the first vent 25 is less than that of the third vent 34.

[0033] Next, the first ventilation port 25 (S05) will be described. Here, too, the first ventilation port 25 is omitted from the illustration, and only the water flow is shown, and only the water flow at the top is shown, omitting that at the bottom. In the case of the first ventilation port 25, the amount of water flowing into the topmost first ventilation port 25 is also greater than the amount of water flowing into the first ventilation port 25 located below.

[0034] Next, a conventionally shaped vent 21 will be described. Here, too, the first vent is omitted from the illustration, and only the water flow is shown. Also, only the uppermost water flow is shown, and the lower water flow is omitted. As is clear from this figure, with the conventionally shaped vent 21, a large amount of water flows into the aircraft interior from the early stages.

[0035] Next, we will explain Figure 7, which shows the state after a certain time T1 has elapsed since the state shown in Figure 6. The contents shown in Figure 7 are the same as those shown in Figure 6, and from the left, they are the third vent 34, the second vent 30, the first vent 25, and the conventional vent 21. First, we look at the third vent 34 (S08) on the far left. Here, three third vents 34 are lined up vertically. A long hole 34a is provided on the outside of the wall 20, and a water return 35 is provided on the inside. Because water falls from above, the amount of water flowing into the top first vent 25 is greater than the amount of water flowing into the first vents 25 located below. Since more time has passed since Figure 6, the amount of water flowing in is also greater, but water is prevented from flowing into the interior of the aircraft.

[0036] At the time shown in Figure 7, water is prevented from entering the inside of the aircraft, but when time T2 has passed since the state shown in Figure 7, a small amount of water has entered the inside of the aircraft, although this is not shown in the figure. Although water infiltration into the inside of the aircraft is confirmed, the amount of water infiltration into the inside of the aircraft has decreased compared to Ref, and water infiltration has been greatly improved.

[0037] Next, the second ventilation opening 30 (S06) will be described. Here, too, the second ventilation opening 30 is omitted from the illustration, and only the water flow is shown. Also, only the uppermost one is shown, and the lower one is omitted. Referring to the second ventilation opening 30 (S06), the amount of water flowing into the ventilation opening is greater in the uppermost second ventilation opening 30 (S06) than in the lower second ventilation opening 30 (S06). Although not shown, when time T2 has elapsed since the state in FIG. 7, no water has entered the interior side of the aircraft, and the intrusion of water into the interior side of the aircraft is suppressed more than that of the third ventilation opening 34 (08).

[0038] Next, the first ventilation opening 25 (S05) will be described. In this case, the amount of water flowing into the ventilation openings is also greater in the uppermost first ventilation opening 25 (S05) than in the lower first ventilation openings 25 (S05). Although not shown in the figure, when time T2 has elapsed since the state in FIG. 7, water has not entered the interior of the aircraft.

[0039] Next, the conventionally shaped ventilation opening (Ref) 21 will be described. Here, too, the first ventilation opening 25 is omitted from the illustration, and only the water flow is shown, and only the water flow at the top is shown, omitting that at the bottom. Here too, with the conventionally shaped ventilation opening 21, a large amount of water flows into the inside of the wall portion 20 even after a certain period of time has passed.

[0040] 5 to 7 and the state after time T2 has elapsed from the state in FIG. 7 (not shown), the following can be seen. First, the third ventilation opening 34 is provided with a water return compared to the conventionally shaped ventilation opening 21, and therefore can significantly prevent water from entering the interior of the aircraft. Furthermore, the first ventilation opening 25 and the second ventilation opening 30 are provided with concave grooves 26, 31 in the upper part, and therefore can further prevent water from entering the interior of the aircraft than the third ventilation opening 34.

[0041] Here, the first ventilation opening 25 and the second ventilation opening 30 are provided with water return openings of the same shape (constant thickness), but the shape of the water return openings may be made to slope from the inside 14 to the outside 13 of the exterior 12 as it goes up.

[0042] Furthermore, here, four differently shaped ventilation openings 21, 25, 30, 34 are provided in multiple locations in the vertical direction, but when actually providing multiple ventilation openings 16 in parallel in the horizontal and vertical directions of the exterior 12 (see Figure 1), only multiple ventilation openings of one shape out of the four differently shaped ventilation openings 21, 25, 30, 34 are provided as ventilation openings 16, and concave grooves 26, 31 are provided only along the top of the topmost ventilation opening 16.

[0043] If the effective ventilation area through which air passes through the ventilation opening is to be increased, it may be provided only on the upper part, or if it is desired to more effectively prevent water from entering, it may be possible to provide concave grooves on the upper part of all the ventilation openings.

[0044] Therefore, no concave grooves are provided above the vents 16 other than those in the top row of the group of vents 16 arranged in parallel.

[0045] Next, the detailed shape of the vent hole that is the basis of the vent hole according to the present disclosure will be described. FIG. 8 is a diagram showing a basic vent hole that is the basic structure of the vent hole according to the present disclosure. Referring to FIG. 8, the upper left side of the figure shows a plan view of the basic vent hole 22 as seen from the outside of the wall portion 20 (see FIG. 4), the right side shows a cross-sectional view of the basic vent hole 22, and the lower part shows a perspective view of the basic vent hole 22 as seen from the outside of the wall portion 20. In the cross-sectional view of the basic vent hole 22 on the right side of FIG. 8, the left side is the inside side of the aircraft, and the right side is the inside side of the aircraft. As shown in the plan view and cross-sectional view of FIG. 8, a concave groove 23 of the same width and depth is provided only above the basic vent hole 22, which is a substantially circular through-hole as seen from the outside of the wall portion 20.

[0046] That is, in the image forming apparatus 10 of the present disclosure, the ventilation opening 16 on the surface of the outer side 13 of the exterior casing 12 shown in FIG. 3 is provided with a basic ventilation opening 22 as shown in FIG. 8 and a concave groove 23 adjacent to the upper surface thereof.

[0047] Referring to the cross-sectional view of Figure 8, the dimensions of the basic vent 22 and the recessed groove 23 are as follows: The diameter of the basic vent 22 is 3 mm. The width a of the recessed groove 23 provided above the basic vent 22 is 0.5 mm, but it is preferably 0.3 mm or more. If this width a is too small, the effect of preventing water intrusion will be reduced. Increasing the thickness will not change the effect, but will increase the area and make the appearance worse.

[0048] [Second embodiment] The thickness b of the wall 24 between the basic vent 22 and the recessed groove 23 formed above it, which conforms to the shape of the upper surface of the vent, is 0.2 mm, but is preferably 0.5 mm or less. If the wall 24 is large and the recessed groove 23 is too far from the basic vent 22, the effect of preventing water intrusion will be reduced. Conversely, if the wall 24 is too thin, it will be impossible to process or will be damaged. Note that the wall 24 is not shown in Figure 5 shown above.

[0049] The depth c of the concave groove 23 will be described later. The position of the top of the basic ventilation opening 22 where the concave groove 23 is provided will also be described later.

[0050] Below, a specific example of a vent based on the structure of the basic vent 22 shown in FIG. 8 will be described. FIG. 9 is a diagram showing a first vent 25 according to the present disclosure. Referring to FIG. 9, a plan view of the wall 20 as seen from the outside is shown on the left side of the figure, and a cross-sectional view of the first vent 25 is shown on the right side. As shown in FIG. 9, a recessed groove 26 of the same width and depth is provided only above the first vent 25, which is substantially circular as seen from the outside of the wall 20, as in FIG. 8. The dimension of the wall 27 between the first vent 25 and the recessed groove 26 provided thereon is the same as dimension b shown for the basic vent 22. In addition, here, the lower portion of the outer side of the wall 20 of the first vent 25 is an elongated hole 25a, and its inner end is closed to form a water return 28. Furthermore, a protrusion 28a protruding outward from the wall 20 is provided at the upper end of the water return 28.

[0051] 10 is a diagram showing a second vent 30 according to the present disclosure. Referring to FIG. 10, a plan view seen from the outside of the wall portion 20 is shown on the left side of the figure, and a cross-sectional view of the second vent 30 is shown on the right side. As shown in FIG. 10, the second vent 30, the recessed groove 31, the wall 32, the water return 33, and the protrusion 33a have the same shapes as those provided in the first vent 25 shown in FIG. 9.

[0052] FIG. 11 is a diagram showing the third vent 34. Referring to FIG. 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 FIG. 11, the third vent 34 has a shape similar to the first and second vents 25, 30 described above, but does not have the concave groove shown in FIGS. 9 and 10. Note that here too, the lower part of the third vent 34 on the outside of the wall 20 is an elongated hole 34a, and its inner end is closed to form a water return 35. In addition, the upper end of this water return 35 is provided with a protrusion 35a facing outward from the wall 20.

[0053] Next, we will explain the angle of the concave grooves provided above the vents of the water injection test fluid analysis device 17. Figure 12 is a diagram showing various cases where the angle of the concave grooves provided above the vents is changed, and shows, from left to right, a conventionally shaped vent 21 (labeled Ref in the diagram), and cases where the angles of the concave grooves are changed to 40°, 100°, 140°, and 192°. Note that all of the vents here are straight through holes with a diameter of 3 mm, and only the conventionally shaped vent 21 does not have a concave groove.

[0054] FIG. 13 is a diagram showing the state of water flowing in when water is dropped from above the concave grooves having the angles shown in FIG. 12, as viewed from the inside of the wall portion 20.

[0055] First, the effect of the concave grooves will be considered with reference to Figures 12 and 13. Comparing the conventionally shaped ventilation hole 21 with other ventilation holes, it can be seen that the ventilation hole with the concave grooves reduces water intrusion.

[0056] Next, we consider the angle of the concave groove. As shown in Figure 13, simulations were performed with angles between both ends of the arc-shaped concave groove of 40°, 100°, 140°, and 192°. The results show that the water intrusion reduction effect increases in the order of 100°, 140°, 40°, and 192°. This is thought to be because when the concave groove angle is 40°, the angle is too small, making it easier for water to infiltrate from areas not covered by the concave groove. Therefore, it is preferable that the angle between both ends of the concave groove along the top surface of the ventilation hole be 100° or more (45° or more on both sides, with the center of the concave groove as the reference).

[0057] Next, we consider the water flow when the angle of the concave groove is large. Figure 14 shows the water flow depending on the groove angle, with the thick lines indicating the direction of water flow for the conventionally shaped vent 21, and for concave groove angles of 40°, 100°, 140°, and 192°, respectively, from left to right. Referring to Figure 14, it is believed that the radial velocity of water decreases in the range exceeding 100°, making it easier for water to enter the vent.

[0058] Next, we will explain the groove depth of the recessed groove indicated by c in the cross-sectional view of Figure 8. Figure 15 shows grooves with different recessed groove depths. In the figure, Ref indicates a conventionally shaped ventilation hole 21 without a groove, 0.15 indicates a groove depth c of 0.15 mm, 0.30 indicates a groove depth c of 0.3 mm, and 0.50 indicates a groove depth c of 0.50 mm. In the figure, water is allowed to flow from above as indicated by the arrows. Figure 16 shows the state of water flowing from above for each groove depth in Figure 15, as viewed from the inside of wall portion 20, and illustrates the degree of water penetration into the inside of wall portion 20.

[0059] Referring to FIG. 16, the depth c of the recessed grooves was 0.15 mm, which resulted in the least amount of water penetration, followed by 0.3 mm, and when it was 0.5 mm, it was the same as the conventional one without recessed grooves.

[0060] From the above, it is believed that the optimum value for the depth c of the concave grooves is 0.15 mm, preferably 0.1 mm or more, and that a range of 0.15 mm to 0.30 mm is effective in reducing water penetration.

[0061] If the groove depth c is greater than 0.3 mm, it becomes difficult for water to flow down the concave groove, so the falling speed does not slow down and the penetration reduction effect is thought to be reduced.

[0062] Next, the shape of the ventilation opening and the shape of the recessed grooves provided thereon will be described. Figures 17 to 19 are diagrams showing the shape of the ventilation opening used in the present disclosure and the shape of the recessed grooves provided thereon other than those described above. Figure 17 is a diagram showing the case where the basic ventilation opening 22 shown in Figure 8 is substantially circular, and shows a case where recessed grooves 38 are provided on the upper half of the ventilation opening 25 at 90° angles each (total of 180°), and a case where recessed grooves 39 are provided on the upper side of the ventilation opening 25 at 70° angles each (total of 140°).

[0063] Figures 18 and 19 are diagrams showing cases where the vent is a substantially regular polygon. Figure 18 shows a case where the vent is a substantially square shape, and here, on the left side, a square vent 40 is placed so that two sides are horizontal, and a linear recessed groove 41 that is longer than one side of the square is provided above the upper side of the vent, and on the right side, a square vent 42 is placed so that the intersection of the two sides is located at the top, and a curved linear recessed groove 43 that is longer than one side of the square is provided above the upper two sides of the vent.

[0064] Figure 19 shows cases where the ventilation opening is pentagonal or larger in shape. Here, on the left side, a ventilation opening 44 of approximately regular pentagonal shape is arranged so that the base of the pentagon is horizontal, and at the top of the approximately regular pentagonal ventilation opening 44, a straight, bent groove 45 that is longer than one side of the regular pentagon is provided above the upper two sides at the corners of the approximately regular pentagon. On the right side, a ventilation opening 46 of approximately regular hexagonal shape is arranged so that the intersection of the two sides is located at the top, and a straight, bent groove 47 that is longer than one side of the approximately regular hexagon is provided above the upper two sides.

[0065] Note that Figures 17 to 19 only show the top row of a group of ventilation openings in which multiple ventilation openings are arranged in parallel, and as shown, concave grooves are provided above the ventilation openings, but no concave grooves are provided above the ventilation openings other than those in the top row of the group of ventilation openings in which multiple ventilation openings are arranged in parallel.

[0066] As described above, in the present disclosure, the ventilation opening of the image forming apparatus is optimally shaped based on the results obtained by the fluid analysis using the water injection test.

[0067] The present disclosure can be implemented in various other forms without departing from its spirit or main features. Therefore, the above-described embodiments are merely examples and should not be interpreted as being limited. All modifications and variations within the scope of the claims of the present disclosure are within the scope of the present disclosure. [Industrial Applicability]

[0068] According to the present disclosure, an image forming apparatus capable of reducing the intrusion of liquid through the ventilation holes can be provided, and therefore is useful as an image forming apparatus. [Explanation of symbols]

[0069] 10 Image forming device 12 Exterior 13 Outside 14 Inside 15 Water-proof recess 16 Ventilation hole 17. Water injection test fluid analysis device 18 Ventilation 19 Water storage section 20 Wall 21 Conventional shaped vent 22 Basic Vent 23, 26, 31, 38, 39 Concave grooves 24, 27, 32 Walls 25 First Vent 25a,30a,34a long hole 28, 33, 35 Water return 28a, 33a, 35a protrusion 30 Second Vent 34 Third Vent 40,42 Square vent 44 Pentagonal shaped ventilation opening 46 Roughly regular hexagonal vent 41, 43, 45, 47 Linear concave grooves

Claims

1. An image forming apparatus including an exterior covering the periphery of the image forming apparatus, and a ventilation hole provided in the exterior for ventilating air 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 that is provided in the vertical direction, The image forming apparatus has a recessed groove that is adjacent to an upper surface of the ventilation hole and is open toward the outside of the exterior, directly above the ventilation hole on the outer surface of the exterior of the image forming apparatus.

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

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

4. The image forming apparatus according to claim 1 , wherein the concave groove is provided adjacent to the upper surface of the ventilation opening along the shape of the upper surface of the ventilation opening.

5. 2. The image forming apparatus according to claim 1, wherein the predetermined shape is a substantially circular shape.

6. 5. The image forming apparatus according to claim 4, wherein an angle between both ends of the concave groove is 45 degrees or more on the left and right sides with respect to the center of the concave groove along the upper surface of the ventilation opening.

7. 2. The image forming apparatus according to claim 1, wherein the predetermined shape is a substantially regular polygon.

8. The image forming apparatus according to claim 7 , wherein the uppermost portion of the ventilation opening is located at a corner of a substantially regular polygon.

9. 3. The image forming apparatus according to claim 2, wherein a concave groove is provided on the ventilation openings in the top row of the ventilation opening group in which the plurality of ventilation openings are arranged in parallel, and no concave groove is provided on the ventilation openings other than the top row of the ventilation opening group in which the plurality of ventilation openings are arranged in parallel.

10. 3. The image forming apparatus according to claim 2, wherein a concave groove is provided on each of the plurality of ventilation openings in the ventilation opening group in which the plurality of ventilation openings are arranged in parallel.

Images