Electromagnetic shielding and electronic devices

Abstract

To provide an electromagnetic shield and an electronic device that can improve the shielding effect with a simple configuration.SOLUTION: An electromagnetic shield 30 includes a first member 31, a second member 32, and a fixing member 33. The first member 31 is cylindrical and has an inner wall 311 that is a wall portion that houses circuit elements inside the cylinder. The inner wall 311 has an outer shape without corners. The second member 32 covers the inner wall 311 from the outer circumferential surface 311a side and closes the opening 311b of the inner wall 311. The fixing member 33 is provided in a string shape and is disposed on the outer surface of the portion of the second member 32 that covers the inner wall 311. The fixing member 33 electrically connects the second member 32 and the inner wall 311 over the entire circumference.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The disclosure in the present specification relates to an electromagnetic shield and an electronic device. [Background Art]

[0002] Patent Document 1 discloses an electronic device including a metal shield case. The content described in the prior art document is incorporated by reference as a description of technical elements in the present specification. [Prior Art Documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Unexamined Patent Publication No. 2022-75671 [Summary of the Invention] [Problem to be Solved by the Invention]

[0004] The shield case disclosed in Patent Document 1 includes a lower case having a substantially rectangular flat shape with one open surface, and an upper case that closes the opening of the lower case. The upper case and the lower case are fixed at four locations by screw fastening. In such a configuration, the shield case is designed so that surface contact can be achieved even in locations other than the screw-fixed portions. However, due to manufacturing variations such as surface roughness and mounting variations, electrical connection at locations other than the fixed portions is not reliable. The gap functions as a slot antenna, and for example, there is a risk that electromagnetic noise leaks. In the above viewpoints or other viewpoints not mentioned, further improvements are demanded for electromagnetic shields and electronic devices.

[0005] One of the objects of the present disclosure is to provide an electromagnetic shield and an electronic device that can enhance the shielding effect with a simple configuration. [Means for Solving the Problem]

[0006] An electromagnetic shield according to one aspect of the disclosure is A first member (31) has a cylindrical shape and a wall portion (311) that has no corners in an axial plan view, and houses circuit elements inside the cylinder, A second member (32) covers the wall from the outer surface side and closes one of the openings in the wall, A string-shaped fixing member (33) is positioned on the outer surface of the portion covering the wall of the second member, and electrically connects the second member and the wall around its entire circumference. Equipped with 、 The first member is a cylindrical member with both ends open in the axial direction. The circuit element is a predetermined circuit element on the circuit board (20), The first component is mounted on a circuit board and accommodates circuit elements through an opening at one end.

[0007] According to the disclosed electromagnetic shielding body, a string-like member is used as the fixing member. By tightening the string-like fixing member, the second member can be brought into contact with the outer surface of the wall and electrically connected. Furthermore, since the outer shape of the wall does not have corners, the second member and the wall can be electrically connected around the entire circumference by tightening the fixing member. Therefore, the shielding effect can be enhanced with a simple configuration.

[0008] Another aspect of the disclosure is an electronic device, A circuit board (20) having a printed circuit board (21) and electronic components (22) mounted on the printed circuit board, An electromagnetic shield (30) covering a predetermined circuit element on a circuit board, Equipped with, The electromagnetic shielding material is A first member (31) has a cylindrical shape and a wall portion (311) that has no corners in an axial plan view, and houses circuit elements inside the cylinder, A second member (32) covers the wall from the outer surface side and closes the openings in the wall that are located away from the printed circuit board, A string-shaped fixing member (33) is positioned on the outer surface of the portion covering the wall of the second member, and electrically connects the second member and the wall around its entire circumference. Includes fruit, The first member is a cylindrical member with both ends open in the axial direction. The first component is mounted on a circuit board and houses circuit elements through an opening at one end.

[0009] According to the disclosed electronic device, a string-shaped member is used as the fixing member. By tightening the string-shaped fixing member, the second member can be brought into contact with the outer peripheral surface of the wall portion and electrically connected thereto. Furthermore, since the outer shape of the wall portion has no corners, tightening the fixing member allows the second member and the wall portion to be electrically connected over the entire circumference. Therefore, the shielding effect can be enhanced with a simple configuration.

[0010] The plurality of aspects disclosed in this specification adopt different technical means from each other to achieve respective objects. The reference signs in parentheses described in the claims and this paragraph exemplify the corresponding relationship with parts of the embodiments described later, and are not intended to limit the technical scope. The objects, features, and effects disclosed in this specification will become clearer by referring to the following detailed description and the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] [Figure 1] It is a perspective view showing an electromagnetic shield and an electronic device according to the first embodiment. [Figure 2] It is an exploded perspective view showing the electromagnetic shield and the electronic device. [Figure 3] It is a sectional view taken along the line III-III in FIG. 1. [Figure 4] It is a plan view showing another example of the first member. [Figure 5] It is a plan view showing another example of the first member. [Figure 6] It is a plan view showing another example of the first member. [Figure 7] It is a sectional view showing another example of the second member. [Figure 8] It is a diagram showing an example of the fixing member. [Figure 9] It is a diagram showing the relationship between a gap and the shielding effect. [Figure 10] It is a diagram showing the relationship between the electrical connection structure and the shielding effect. [Figure 11] It is a cross-sectional view showing the electromagnetic shield according to the second embodiment. [Figure 12] It is a cross-sectional view showing another example of the second member. [Figure 13] It is a plan view showing the electromagnetic shield and the electronic device according to the third embodiment. [Figure 14] It is a cross-sectional view taken along line XIV-XIV in Fig. 13. [Figure 15] It is a cross-sectional view showing the electromagnetic shield and the electronic device according to the fourth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, a plurality of embodiments will be described with reference to the drawings. Corresponding components in each embodiment are denoted by the same reference numerals, and overlapping descriptions may be omitted. When only a part of the configuration is described in each embodiment, the configurations of other previously described embodiments can be applied to the remaining parts of the configuration. Moreover, configurations of a plurality of embodiments are not limited to the combinations explicitly described in the description of each embodiment, and partial combinations of configurations of a plurality of embodiments are also permitted even if not explicitly stated, provided that there is no obstacle to such combination.

[0013] Note that the description of A and / or B means at least one of A and B. That is, it may include only A, only B, or both A and B.

[0014] (First Embodiment) First, a schematic configuration of the electronic device will be described.

[0015] <Electronic Device> Fig. 1 is a perspective view showing the electronic device. Fig. 2 is an exploded perspective view of the electronic device. Fig. 3 is a cross-sectional view taken along line III-III in Fig. 1. In Fig. 3, resists and wirings are omitted for convenience. Further, for convenience, metal hatching is applied to electronic components.

[0016] In the following, the axial direction of the cylindrical inner wall is referred to as the Z direction. The direction perpendicular to the Z direction is referred to as the X direction, and the direction perpendicular to both the Z and X directions is referred to as the Y direction. Unless otherwise specified, the planar shape is defined as the shape viewed from the Z direction, in other words, the shape along the XY plane defined by the X and Y directions. The planar view from the Z direction is sometimes simply referred to as the planar view.

[0017] As shown in Figures 1, 2, and 3, the electronic device 10 comprises a circuit board 20 and an electromagnetic shield 30. The electronic device 10 may be fixed to a frame (not shown) of a mobile body. The frame is, for example, the chassis of the mobile body. The mobile body is, for example, a vehicle, an aircraft, a ship, construction machinery, agricultural machinery, etc. As an example, the electronic device 10 of this embodiment is mounted on a vehicle.

[0018] The circuit board 20 comprises a printed circuit board 21 and electronic components 22. The printed circuit board 21 is sometimes referred to as a board or wiring board. The printed circuit board 21 has one side 21a and a back side 21b which is the opposite side of the side 21a in the thickness direction. The planar shape of the printed circuit board 21 is not particularly limited. As an example, the printed circuit board 21 of this embodiment is substantially rectangular in planar shape. When the electromagnetic shield body 30 (first member 31) is mounted, the thickness direction of the printed circuit board 21 is substantially parallel to the Z direction.

[0019] The printed circuit board 21 comprises an insulating substrate 211 and wiring elements (not shown) arranged on the insulating substrate 211. The insulating substrate 211 is formed using an electrically insulating material such as resin. The insulating substrate 211 may consist of, for example, only resin, or a combination of resin with glass cloth, nonwoven fabric, etc. The printed circuit board 21 may have fixing holes 212 at the four corners of its approximately rectangular shape for fixing to a chassis (frame) of a mobile body.

[0020] The wiring element is formed using a highly conductive metallic material such as Cu. The wiring element includes a wiring layer. The wiring layer may be referred to as wiring, wiring pattern, etc. The wiring layer may be formed, for example, by patterning a metal foil or by printing. In addition to the wiring layer, the wiring element may include through-hole lands or via conductors. Through-hole lands are formed on the walls of through-holes that penetrate the printed circuit board 21 in the Z direction. Through-hole lands may be formed around the opening along with the walls of the through-holes. Via conductors are formed by placing a conductor, such as plating, in a through-hole (via) formed in the insulating layer constituting the insulating substrate 211. Via conductors electrically connect, for example, wiring layers arranged on different layers.

[0021] The wiring element may include a wiring layer disposed on the surface of the insulating substrate 211 on one side 21a, or a wiring layer disposed on the surface of the back side 21b. The wiring element may also include a wiring layer disposed inside the insulating substrate 211. The wiring layer may be disposed on the insulating substrate 211 in a single layer or in multiple layers.

[0022] The electronic components 22 are mounted on the printed circuit board 21. Multiple electronic components 22 are mounted on the printed circuit board 21. The electronic components 22 are generally arranged on one side 21a and / or the back side 21b of the printed circuit board 21. At least some of the electronic components 22 may be embedded in an insulating substrate 211. The electronic components 22, together with the wiring elements described above, form a circuit. The wiring elements and / or the electronic components 22 constitute the circuit elements.

[0023] The electromagnetic shield 30 covers predetermined circuit elements on the circuit board 20. The electromagnetic shield 30 may be positioned to cover all circuit elements formed on the circuit board 20, or it may be positioned to cover specific circuit elements. The electromagnetic shield 30 may be positioned to cover specific circuit elements that are noise sources, or it may be positioned to cover specific circuit elements from which the influence of external noise is to be suppressed. The electromagnetic shield 30 may, for example, cover wiring elements, or cover electronic components 22. Of course, it may also cover wiring elements and electronic components 22.

[0024] <Electromagnetic shielding> The electromagnetic shield 30 may house the circuit board 20 or be mounted on the printed circuit board 21. As an example, in this embodiment, the electromagnetic shield 30 is mounted on the printed circuit board 21. The electromagnetic shield 30 covers a specific circuit element that is a source of noise.

[0025] The electromagnetic shielding body 30 comprises a first member 31, a second member 32, and a fixing member 33. The first member 31 is positioned inside the second member 32 and is therefore sometimes referred to as an internal member. The first member 31 is the mounting portion of the printed circuit board 21 in the electromagnetic shielding body 30 and is therefore sometimes referred to as a board connection member or the like.

[0026] The first member 31 has an inner wall 311. The inner wall 311 is cylindrical in shape and extends in the Z direction. The inner wall 311 has a predetermined height in the Z direction and is ring-shaped in plan view. The inner wall 311 may be referred to as a wall portion, cylindrical portion, or side wall. The inner wall 311 has an outer surface 311a and openings 311b and 311c. Opening 311b is the opening on the inner wall 311 opposite to the printed circuit board 21. Opening 311c is the opening on the inner wall 311 on the printed circuit board 21 side. The inner wall 311 houses circuit elements within the cylinder. In the example shown in Figures 1 to 3, it houses electronic components 22 arranged on one surface 21a.

[0027] The first member 31 may have only an inner wall 311, or it may have a portion connected to the inner wall 311. For example, the portion connected to the inner wall 311 may have a flange extending in the radial direction from the end of the inner wall 311 on the printed circuit board 21 side. As an example, the first member 31 in this embodiment has only an inner wall 311. The inner wall 311 is soldered to a land (not shown), which is part of the wiring layer provided on the surface layer on one side 21a of the printed circuit board 21.

[0028] The inner wall 311 has an outer shape that does not have corners in a plan view. An outer shape that does not have corners is a closed, convex shape that does not intersect. The outer shape of the inner wall 311 may be symmetrical or asymmetrical. An oval shape may be adopted as the outer shape of the inner wall 311. As shown in Figures 1 and 2, the outer shape of the inner wall 311 may be an ellipse. An ellipse is a type of oval shape. Other oval shapes that may be adopted include an oblong or egg shape. For example, as shown in the alternative example in Figure 4, the outer shape of the inner wall 311 may be a rounded oblong. A rounded oblong is composed of two parallel lines of equal length and two semicircles. A rounded rectangle is a shape that is mainly used, for example, on the track of an athletics stadium.

[0029] The outer shape of the inner wall 311 may have straight sections, such as the rounded oval shape described above, or it may have a shape without straight sections, such as in the alternative example shown in Figure 5. The outer shape of the inner wall 311 may also be a curve that is differentiable around its entire circumference. The outer shape without straight sections is not limited to the example shown in Figure 5. For example, the outer shape of the inner wall 311 may be circular (perfectly circular), as in the alternative example shown in Figure 6.

[0030] The inner shape of the inner wall 311 may be similar to the outer shape. The thickness of the inner wall 311 may be approximately uniform around its entire circumference. The inner shape of the inner wall 311 may be different from the outer shape. The thickness of the inner wall 311 may be partially different. The inner wall 311 should have rigidity such that it hardly deforms when tightened by the fixing member 33. The inner wall 311 may be thicker than, for example, the outer wall 321.

[0031] The first member 31 is formed using a metal material suitable for electromagnetic shielding. The first member 31 may be formed using only a metal material. The first member 31 may be formed using an electrical insulating material such as resin and a metal material. For example, the outer surface of a cylindrical resin molded body may be plated. For electrical connection with the second member 32, at least the outer surface 311a of the inner wall 311 is a metal surface. As an example, the first member 31 in this embodiment is formed using only a metal material.

[0032] The second member 32 is sometimes referred to as an outer member because it is positioned outside the inner wall 311 of the first member 31. The second member 32 is sometimes referred to as a cover, lid, etc., because it covers the first member 31. The second member 32 is molded into a predetermined shape and may have an outer wall 321 and a top wall 322. The outer wall 321 is positioned to surround the inner wall 311. The outer wall 321 is sometimes referred to as a side wall, cylindrical part, etc. The outer wall 321 is cylindrical, like the inner wall 311. The outer wall 321 has a predetermined height in the Z direction and is ring-shaped in plan view. To suppress localized stress concentration during tightening, the thickness of the outer wall 321 may be made almost uniform around its entire circumference. The outer wall 321 has a shape similar to the outer shape of the inner wall 311 in plan view. The outer wall 321 has an outer circumferential surface 321a and an inner circumferential surface 321b.

[0033] The outer wall 321 is electrically connected to the inner wall 311 around its entire circumference by the tightening of the fixing member 33. The inner surface 321b of the outer wall 321 is in continuous contact with the outer surface 311a of the inner wall 311 over its entire circumference. The outer wall 321 is in continuous contact with the inner wall 311 over its entire circumference, at least at the tightening portion by the fixing member 33 and its surroundings. The inner surface 321b of the outer wall 321 may be in contact with the outer surface 311a of the inner wall 311 over its entire surface. The outer wall 321 is configured to be deformable by the tightening of the fixing member 33 so as to contact the inner wall 311. For example, the thickness of the outer wall 321 may be relatively thin.

[0034] The top wall 322 is connected to the outer wall 321 and closes one of the openings in the cylindrical outer wall 321. The top wall 322 is sometimes referred to as the bottom or bottom wall. The top wall 322 closes the opening 311b in the inner wall 311. The second member 32 is a lid-like (box-like) structure of a predetermined depth with one side open. In a fixed state, the top wall 322 may be in contact with the open end of the inner wall 311, or there may be a gap between it and the open end.

[0035] The second member 32 is formed using a metal material suitable for electromagnetic shielding. The second member 32 may be formed using only a metal material. The second member 32 may be formed using an electrical insulating material such as resin and a metal material. For example, the inner surface of a lid-shaped resin molded body may be plated. At least the inner surface of the lid-shaped body is a metal surface for electrical connection with the first member 31 and for electromagnetic shielding. As an example, the second member 32 in this embodiment is formed using only a metal material.

[0036] The second member 32 is not limited to being pre-formed into a predetermined shape as described above. For example, as shown in the alternative example in Figure 7, a second member 32 formed using cloth may be used. The cloth may be, for example, metallic cloth. Instead of cloth, a film or sheet may be used. In other words, a flexible material may be used. Such a second member 32 does not have the outer wall 321 and top wall 322 as described above in its pre-fixed state. When fixed, it deforms to conform to the first member 31 and has an outer wall 321 and top wall 322 in the fixed state.

[0037] The fixing member 33 is string-shaped and is used to tighten and continuously connect (electrically connect) the second member 32 to the outer circumferential surface 311a of the inner wall 311 over its entire circumference. String-shaped means long and narrow. String-shaped also includes strip-shaped (band-shaped). The material of the fixing member 33 is not particularly limited. For example, an elastically deformable material such as rubber may be used, or a material that can be shrunk by the application of external force, such as heat-shrinkable tubing, may be used. The fixing member 33 may be tightened by spring force. For example, a spring-type hose clamp may be used.

[0038] As the fixing member 33, a device equipped with a mechanism for adjusting the fixing strength, such as a screw-type hose clamp, may be used. Figure 8 shows an example of the fixing member 33. The fixing member 33 has a metal band 331 and a strength adjustment mechanism 332. The strength adjustment mechanism 332, including a screw (bolt), changes the diameter of the metal band 331 in accordance with the tightening of the screw, thereby adjusting the fixing strength. By controlling the torque value when tightening the screw, the first member 31 and the second member 32 can be fixed with a predetermined (uniform) force.

[0039] The fixing member 33 is positioned in the Z direction to allow the outer wall 321 to continuously contact the outer circumferential surface 311a of the inner wall 311 all around. It is preferable to position it so as to avoid the end of the outer circumferential surface 321a of the outer wall 321 that is on the side of the top wall 322. Preferably, it is positioned in the central part of the outer circumferential surface 321a of the outer wall 321, excluding both ends. By positioning the fixing member 33 in the central part, the contact area can be made larger.

[0040] The number of string-like fixing members 33 is not particularly limited. There may be one or more. A single fixing member 33 may be wrapped multiple times.

[0041] <Simulation Results> Figure 9 shows the relationship between gaps and shielding effect. The gap refers to the width of the electrically unconnected portion in the electromagnetic shield, i.e., the width of the shielding hole. As mentioned above, the gaps in the electromagnetic shield function as slot antennas. The results in Figure 9 support this point. It is clear from the results shown in Figure 9 that the larger the gap, the lower the shielding effect.

[0042] Figure 10 shows the relationship between the electrical connection structure and the shielding effect. In Figure 10, the configuration with the electromagnetic shield removed from the electronic device in Figure 1 is used as a baseline, and the difference from the baseline is shown as the shielding effect. The solid line shows the configuration shown in Figure 1, i.e., the result of this example. The dashed and dotted lines show the results of reference examples. In all of the reference examples, the fixed members are removed from the electromagnetic shield. The configurations of the first and second members are the same as in this example. The reference example shown by the dashed line shows the result of a configuration in which the first and second members are discretely connected at four points. The reference example shown by the dotted line shows the result of a configuration in which there are no contact points between the first and second members. It is clear from the results shown in Figure 10 that the shielding effect can be enhanced by making electrical connections all around.

[0043] <Summary of the First Embodiment> According to this embodiment, the electromagnetic shielding body 30 includes a string-shaped fixing member 33. By tightening the string-shaped fixing member 33, the second member 32 can be brought into contact with the outer peripheral surface 311a of the inner wall 311 of the first member 31, thereby enabling an electrical connection. Furthermore, in plan view, the outer shape of the inner wall 311 has no corners. Therefore, by tightening the fixing member 33, the second member 32 and the inner wall 311 can be electrically connected around their entire circumference. Continuous electrical connection can be achieved without being affected by manufacturing variations such as surface roughness and mounting variations. Thus, the shielding effect can be enhanced with a simple configuration. The shielding effect can be enhanced with an inexpensive configuration.

[0044] Furthermore, because the connection is made continuously around the entire circumference, the fixing strength can be increased. This ensures that even when applied to a moving object, the fixing strength can withstand vibration tests.

[0045] Furthermore, since a string-like fixing member 33 is used and the fixing member 33 is positioned on the outer peripheral surface 321a of the outer wall 321 of the second member 32, the tightening state can be easily released. In other words, the connection between the first member 31 and the second member 32 can be easily released. By removing the second member 32, for example, evaluation and inspection of circuit elements can be performed.

[0046] The first member 31 may be a cylindrical member with both ends open in the axial direction. This allows for a simpler structure while enhancing the shielding effect.

[0047] The first component 31 may be mounted on the printed circuit board 21. The first component 31 houses the circuit elements when mounted on the printed circuit board 21. Since the first component 31 provides the mounting portion for the printed circuit board 21 in the electromagnetic shield body 30, no other mounting portion is required. Therefore, the shielding effect can be enhanced with a simple configuration.

[0048] The outer shape of the inner wall 311 of the first member 31 may be oval. Since the oval shape has no corners, it is possible to suppress localized stress concentration when tightening with the string-like fixing member 33. Therefore, the fixing member 33 can electrically connect all around.

[0049] The outer shape of the inner wall 311 may be a shape without straight sections. By not having straight sections, the stress during tightening becomes more easily distributed. In other words, localized stress concentration can be effectively suppressed. Therefore, electrical connection around the entire circumference can be made more reliable. Note that a part of the oval shape does not have straight sections, like an ellipse.

[0050] The outer shape of the inner wall 311 may be circular. This allows for even distribution of stress during tightening. In other words, localized stress concentration can be suppressed more effectively. Therefore, electrical connection around the entire circumference can be made even more reliable.

[0051] The outer wall 321 of the second member 32 may be similar in shape to the outer shape of the inner wall 311 in a plan view. Due to the similarity, electrical connections can be easily made around the entire circumference by tightening. Cloth, film, or sheet may be used as the second member 32. In this case, since the second member 32 is flexible, electrical connections can be easily made around the entire circumference by tightening.

[0052] The fixing member 33 may have a strength adjustment mechanism 332 for adjusting the fixing strength between the first member 31 and the second member 32. This allows the first member 31 and the second member 32 to be fixed with a predetermined (uniform) force by controlling the torque value.

[0053] (Second Embodiment) This embodiment is a modification based on the preceding embodiment, and the description of the preceding embodiment can be referenced. In the preceding embodiment, the arrangement of the fixing member 33 with respect to the outer peripheral surface 321a of the outer wall 321 was not specifically mentioned. In addition, a mechanism for guiding the fixing member 33 may be provided on the outer wall 321 of the second member 32.

[0054] Figure 11 is a cross-sectional view showing the electromagnetic shielding body 30 according to this embodiment. Figure 11 corresponds to Figure 3. In Figure 11, for convenience, the number of fixing members 33 is shown as one. Also, the circuit board 20 is omitted.

[0055] The second member 32 has a recess 323 on its outer circumferential surface 321a as a guide mechanism. The recess 323 is recessed relative to the rest of the outer circumferential surface 321a. The recess 323 is continuously provided around the entire circumference of the outer circumferential surface 321a. The position of the recess 323 in the Z direction is the same (same height) around the entire circumference. The recess 323 accommodates a string-like fixing member 33 around its entire circumference. The recess 323 has a depth and width to accommodate the fixing member 33.

[0056] The fixing member 33 is positioned along the guide mechanism. The fixing member 33 may be positioned such that a portion of it is located within the space of the recess 323 and another portion protrudes from the recess 323 around its entire circumference. The fixing member 33 may be positioned so that it is located within the space of the recess 323 around its entire circumference. The fixing member 33 is positioned along the recess 323. The position of the fixing member 33 is determined by the recess 323. The position of the fixing member 33 is restricted by the recess 323.

[0057] An example of providing a recess 323 as a guide mechanism has been shown, but the invention is not limited to this. For example, as shown in Figure 12, a protrusion 324 may be provided on the outer circumferential surface 321a. The protrusion 324 protrudes from the rest of the outer circumferential surface 321a. The protrusion 324 is provided so as to surround the outer circumferential surface 311a (inner wall 311) in a plan view. The protrusion 324 may be provided continuously or discontinuously around the entire circumference of the outer circumferential surface 321a. The position of the protrusion 324 in the Z direction is the same (same height) around the entire circumference. The protrusion 324 has a predetermined height.

[0058] The fixing member 33 is positioned along the guide mechanism. The fixing member 33 is positioned along the protrusion 324. The fixing member 33 is positioned in contact with one side surface of the protrusion 324. The fixing member 33 is positioned in contact with one side surface of the protrusion 324 and the peripheral portion of the protrusion 324 on the outer circumferential surface 321a. The fixing member 33 may be positioned such that a portion of it is located radially outward from the protruding tip of the protrusion 324. The fixing member 33 may be positioned so as not to protrude outward from the protruding tip of the protrusion 324. The position of the fixing member 33 is determined by the protrusion 324. The position of the fixing member 33 is restricted by the protrusion 324. The other configurations are the same as those described in the prior embodiment.

[0059] Alternatively, multiple protrusions 324 may be provided, and the fixing member 33 may be placed in the recess formed by the adjacent protrusions 324 and the portion of the outer circumferential surface 321a between the protrusions 324.

[0060] <Summary of the second embodiment> According to this embodiment, a mechanism for guiding the fixing member 33 is provided on the outer peripheral surface 321a of the outer wall 321. Specifically, recesses 323 and protrusions 324 are provided. This restricts the arrangement of the string-like fixing member 33. In other words, the fixing member 33 can be positioned in a predetermined location. Therefore, the fixing strength can be increased.

[0061] The configuration described in this embodiment can be combined with any of the configurations described in the prior embodiment, excluding the configuration in which cloth, film, or sheet is used as the second member 32.

[0062] (Third embodiment) This embodiment is a modification based on the prior embodiment, and the description of the prior embodiment can be referenced. In the prior embodiment, the first member 31 was surface-mounted onto the printed circuit board 21. Alternatively, the first member 31 may be insert-mounted onto the printed circuit board 21.

[0063] Figure 13 is a plan view of the electronic device 10 according to this embodiment, as seen from the back surface 21b side of the printed circuit board 21. For convenience, solder is omitted in Figure 13. Figure 14 is a cross-sectional view along the line XIV-XIV in Figure 13.

[0064] As shown in Figures 13 and 14, the printed circuit board 21 has a plurality of through-holes 213. Each of the through-holes 213 penetrates the printed circuit board 21 in the Z direction. Lands are provided on the walls of the through-holes 213. Lands are wiring elements. Lands are sometimes referred to as through-hole lands. The plurality of through-holes 213 are provided along the lower end of the inner wall 311 at predetermined intervals.

[0065] The printed circuit board 21 may have a ground layer 214 located on its back surface 21b. The ground layer 214 provides a reference potential (ground potential) on the printed circuit board 21. The ground layer 214 is part of the wiring layers. The ground layer 214 has a larger area than the other wiring layers. The ground layer 214 may be located on almost the entire back surface 21b, or on a portion of the back surface 21b, including the area around the through-holes 213.

[0066] The inner wall 311 of the first member 31 has a plurality of legs 312 extending in the Z direction from the end on the printed circuit board 21 side. The legs 312 are provided at predetermined intervals around the entire circumference of the inner wall 311. Each of the legs 312 is inserted and mounted on the printed circuit board 21 with the corresponding through-hole 213 inserted through it. Each of the legs 312 is connected to the through-hole land via solder 40. The portion of the legs 312 protruding from the back surface 21b is connected to the ground layer 214 via solder 40.

[0067] The spacing of the legs 312 is set to prevent radio waves from leaking between them. By setting the spacing to be less than or equal to half a wavelength of a predetermined frequency, it functions as a shielding wall that blocks noise of a predetermined frequency. If it is desired to block noise of multiple frequencies, the spacing should be less than or equal to half a wavelength of the lowest frequency. The spacing of the through-holes 213 is set so that the legs 312 function as a shielding wall. The other configurations are the same as those described in the prior embodiment.

[0068] <Summary of the third embodiment> According to this embodiment, the first member 31 has a plurality of legs 312. The legs 312 are inserted and mounted into the through-holes 213 of the printed circuit board 21. The plurality of legs 312 and the through-holes 213 are provided at predetermined intervals so that the legs 312 function as a shielding wall. Therefore, leakage of electromagnetic noise to the back surface 21b of the printed circuit board 21 can be prevented.

[0069] A ground layer 214 may be provided on the back surface 21b of the printed circuit board 21, and each of the legs 312 may be connected to the ground layer 214. Since the legs 312 and the ground layer 214 are electrically connected, the shielding structure including the electromagnetic shield 30 and the ground layer 214 can surround the circuit element. Therefore, leakage of electromagnetic noise can be prevented in all directions, including the area directly beneath the circuit element.

[0070] The configuration described in this embodiment can be combined with any of the configurations described in the prior embodiment, excluding the configuration in which cloth, film, or sheet is used as the second member 32.

[0071] <Variation> Instead of the legs 312, a shielding wall using via conductors may be provided within the printed circuit board 21. The via conductors are provided at predetermined intervals along the end of the inner wall 311. The spacing between the via conductors should be less than or equal to half a wavelength of the frequency of the noise to be blocked. If noise of multiple frequencies is to be blocked, the spacing should be less than or equal to half a wavelength of the lowest frequency. The via conductors may also be electrically connected to the inner wall 311.

[0072] (Fourth Embodiment) This embodiment is a modification based on the prior embodiment, and the description of the prior embodiment can be referenced. In the prior embodiment, the first member 31 had only an inner wall 311. Alternatively, the first member 31 may have a bottom wall. In the prior embodiment, the electromagnetic shield 30 was mounted on the printed circuit board 21. Alternatively, the electromagnetic shield 30 may house the printed circuit board 21.

[0073] Figure 15 is a cross-sectional view showing an electronic device 10 according to this embodiment. Figure 15 corresponds to Figure 3. The first member 31 has an inner wall 311 and a bottom wall 313. The bottom wall 313 is connected to the end of the inner wall 311 opposite to the top wall 322 and closes the opening 311c. The first member 31 is box-shaped with one side open. In this configuration, the first member 31 is sometimes referred to as the lower case and the second member 32 as the upper case. The first member 31 and the second member 32 are sometimes referred to as the housing.

[0074] The circuit board 20 is positioned in the space defined by the first member 31 and the second member 32. The other configurations are the same as in the previous embodiment.

[0075] <Summary of the fourth embodiment> According to this embodiment, the first member 31 has a bottom wall 313. The first member 31 and the second member 32 form a so-called housing. In this configuration, the inner wall 311 has an outer shape without corners, similar to the configuration described in the prior embodiment. The fixing member 33 is string-shaped and electrically connects the outer wall 321 to the outer peripheral surface 311a of the inner wall 311 around its entire circumference by tightening. In other words, even when a circuit board 20 is housed inside the electromagnetic shield body 30, the shielding effect can be enhanced with a simple configuration.

[0076] The configuration described in this embodiment can be combined with the configurations described in the prior embodiment, excluding the configurations that are essential to be mounted on the printed circuit board 21.

[0077] (Other embodiments) The disclosures in this specification and drawings are not limited to the exemplary embodiments. The disclosures include the exemplary embodiments and variations thereof by those skilled in the art. For example, the disclosures are not limited to combinations of parts and / or elements shown in the embodiments. The disclosures are implementable in a variety of combinations. The disclosures may have additional parts that can be added to the embodiments. The disclosures include those in which parts and / or elements of the embodiments have been omitted. The disclosures include substitutions or combinations of parts and / or elements between one embodiment and another. The scope of the disclosed technical areas is not limited to the descriptions of the embodiments. Some of the scope of the disclosed technical areas are indicated by the claims and should be understood to include all modifications within the meaning and scope equivalent to the claims.

[0078] The disclosures in the specification and drawings are not limited by the claims. The disclosures in the specification and drawings encompass the technical ideas described in the claims and extend to a wider and more diverse range of technical ideas than those described in the claims. Therefore, a variety of technical ideas can be extracted from the disclosures in the specification and drawings without being bound by the claims.

[0079] When an element or layer is referred to as “on top of,” “connected to,” “connected to,” or “joined,” it may be directly on top of, connected to, connected to, or joined to another element or layer, and there may also be an intervening element or layer. In contrast, when an element is referred to as “directly on top of,” “directly connected to,” “directly connected to,” or “directly joined to” another element or layer, there is no intervening element or layer. Other words used to describe relationships between elements should be interpreted in a similar manner (e.g., “between” vs. “directly between,” “adjacent” vs. “directly adjacent,” etc.). As used in this specification, the term “and / or” includes any combination with respect to one or more of the enumerated items relating to the relationship, and all combinations thereof.

[0080] Spatially relative terms such as "inside," "outside," "back," "below," "low," "above," and "high" are used here to facilitate descriptions of the relationship between one element or feature and other elements or features, as illustrated. Spatially relative terms may be intended to encompass different orientations of the device in use or operation, in addition to the orientation depicted in the drawings. For example, if the device in the drawing is turned upside down, an element described as "below" or "directly below" another element or feature will be oriented "above" the other element or feature. Thus, the term "below" can encompass both up and down orientations. The device may also be oriented in other directions (it may be rotated 90 degrees or in other directions), and the spatially relative descriptors used in this specification will be interpreted accordingly.

[0081] (Disclosure of technical ideas) This specification discloses several technical concepts, as listed in the following paragraphs. Some paragraphs are written in a multiple dependent form, where subsequent paragraphs optionally refer to preceding paragraphs. Furthermore, some paragraphs are written in a multiple dependent form, referring to other multiple dependent forms. These paragraphs written in multiple dependent forms define several technical concepts.

[0082] <Technical philosophy 1> A first member (31) has a cylindrical shape and a wall portion (311) that has no corners in an axial plan view, and houses circuit elements inside the cylinder, A second member (32) covers the wall portion from the outer peripheral surface side and closes one of the openings in the wall portion, A string-shaped fixing member (33) is disposed on the outer surface of the portion of the second member that covers the wall portion, and electrically connects the second member and the wall portion around its entire circumference, An electromagnetic shielding body equipped with the following features.

[0083] <Technical philosophy 2> The electromagnetic shielding body according to technical concept 1, wherein the first member is a cylindrical member with both ends open in the axial direction.

[0084] <Technical philosophy 3> The first component is an electromagnetic shielding body as described in Technical Concept 2, which is mounted on a printed circuit board (21).

[0085] <Technical philosophy 4> The aforementioned wall portion is a side wall, The first member has a bottom wall (313) that is connected to the side wall and closes one of the openings in the side wall, The second member is an electromagnetic shielding body according to technical concept 1, wherein the second member is positioned at the end of the side wall opposite to the bottom wall.

[0086] <Technical philosophy 5> The electromagnetic shielding body described in any one of technical concepts 1 to 4, wherein the outer shape of the wall portion is oval.

[0087] <Technical philosophy 6> The electromagnetic shielding body according to any one of the technical ideas 1 to 4, wherein the outer shape of the wall portion does not have a straight section.

[0088] <Technical philosophy 7> The electromagnetic shielding body according to technical concept 6, wherein the outer shape of the wall portion is circular.

[0089] <Technical philosophy 8> The aforementioned wall portion is an inner wall, The second member includes an outer wall (321) arranged to surround the inner wall, and a top wall (322) connected to the outer wall and closing one of the openings in the outer wall. The electromagnetic shielding body according to any one of technical ideas 1 to 7, wherein the outer wall has a shape similar to the outer shape of the inner wall in the plan view.

[0090] <Technical philosophy 9> The electromagnetic shielding body according to any one of technical ideas 1 to 7, wherein the second member is formed using cloth, film, or sheet.

[0091] <Technical Thought 10> The aforementioned fixing member has a mechanism (332) for adjusting the fixing strength, and is an electromagnetic shielding body according to any one of technical ideas 1 to 9.

[0092] <Technical Thought 11> The electromagnetic shield body according to technical concept 8, wherein the second member has a mechanism (323, 324) on the outer surface of the outer wall for guiding the fixing member.

[0093] <Technical Thought 12> The electromagnetic shielding body according to technical concept 11, wherein the mechanism is a recess (323) or a protrusion (324) provided on the outer circumferential surface. [Explanation of Symbols]

[0094] 10...Electronic device, 20...Circuit board, 21...Printed circuit board, 21a...One side, 21b...Back side, 211...Insulating substrate, 212...Fixing hole, 213...Through hole, 214...Ground layer, 22...Electronic component, 30...Electromagnetic shield, 31...First member, 311...Inner wall, 311a...Outer surface, 311b,311c...Opening, 312...Legs, 313...Bottom wall, 32...Second member, 321...Outer wall, 321a...Outer surface, 321b...Inner surface, 322...Top wall, 323...Recess, 324...Protrusion, 33...Fixing member, 331...Metal band, 332...Strength adjustment mechanism, 40...Solder

Claims

1. A first member (31) has a cylindrical shape and a wall portion (311) that has no corners in an axial plan view, and houses circuit elements inside the cylinder, A second member (32) covers the wall portion from the outer circumferential side and closes one of the openings in the wall portion, A string-shaped fixing member (33) is disposed on the outer surface of the portion of the second member that covers the wall portion, and electrically connects the second member and the wall portion around its entire circumference, Equipped with, The first member is a cylindrical member with both ends open in the axial direction, The aforementioned circuit element is a predetermined circuit element on the circuit board (20), The first member is an electromagnetic shield that is mounted on the circuit board and houses the circuit element through an opening at one end.

2. The electromagnetic shielding body according to claim 1, wherein the outer shape of the wall portion is oval.

3. The electromagnetic shielding body according to claim 1, wherein the outer shape of the wall portion does not have a straight section.

4. The electromagnetic shielding body according to claim 3, wherein the outer shape of the wall portion is circular.

5. The aforementioned wall portion is an inner wall, The second member includes an outer wall (321) arranged to surround the inner wall, and a top wall (322) connected to the outer wall and closing one of the openings in the outer wall. The electromagnetic shielding body according to claim 1, wherein the outer wall has a shape similar to the outer shape of the inner wall in a plan view.

6. The electromagnetic shielding body according to claim 1, wherein the second member is formed using cloth, film, or sheet.

7. The electromagnetic shielding body according to claim 1, wherein the fixing member has a mechanism (332) for adjusting the fixing strength.

8. The electromagnetic shield body according to claim 5, wherein the second member has a mechanism (323, 324) on the outer circumferential surface of the outer wall for guiding the fixing member.

9. The electromagnetic shielding body according to claim 8, wherein the mechanism is a recess (323) or a protrusion (324) provided on the outer circumferential surface.

10. A first member (31) has a cylindrical shape and a wall portion (311) that has no corners in an axial plan view, and houses circuit elements inside the cylinder, A second member (32) covers the wall portion from the outer circumferential side and closes one of the openings in the wall portion, A string-shaped fixing member (33) is disposed on the outer surface of the portion of the second member that covers the wall portion, and electrically connects the second member and the wall portion around its entire circumference, Equipped with, The second member is an electromagnetic shield, formed using cloth, film, or sheet.

11. The electromagnetic shielding body according to claim 10, wherein the first member is a cylindrical member having openings at both ends in the axial direction.

12. The first component is mounted on a printed circuit board (21), as described in claim 11.

13. The aforementioned wall portion is a side wall, The first member has a bottom wall (313) that is connected to the side wall and closes one of the openings in the side wall, The electromagnetic shielding body according to claim 10, wherein the second member is disposed at the end of the side wall opposite to the bottom wall.

14. A circuit board (20) having a printed circuit board (21) and electronic components (22) mounted on the printed circuit board, An electromagnetic shield (30) covering a predetermined circuit element on the circuit board, Equipped with, The electromagnetic shielding body is A first member (31) that is cylindrical and has a wall portion (311) having an outer shape without corners in a plan view in the axial direction, and houses the circuit element inside the cylinder, A second member (32) covers the wall portion from the outer peripheral surface side and closes the openings in the wall portion that are located away from the printed circuit board, A string-shaped fixing member (33) is disposed on the outer surface of the portion of the second member that covers the wall portion, and electrically connects the second member and the wall portion around its entire circumference, Includes, The first member is a cylindrical member with both ends open in the axial direction, The first member is mounted on the circuit board and houses the circuit element through an opening at one end, in an electronic device.

15. The first member has a plurality of legs (312) extending from the end of the wall portion on the printed circuit board side and provided at predetermined intervals around its entire circumference. The electronic device according to claim 14, wherein the printed circuit board has a plurality of through-holes (213) into which the plurality of legs are individually inserted and mounted.

16. The printed circuit board has a ground layer (214) that provides a reference potential on the side opposite to the side on which the wall portion is arranged. The electronic device according to claim 15, wherein each of the legs is connected to the ground layer.

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