US-12628320-B2 - Electromagnetic shielding body and electronic device

US12628320B2US 12628320 B2US12628320 B2US 12628320B2US-12628320-B2

Abstract

An electromagnetic shielding body includes a first member, a second member, and a fixing member. The first member has a cylindrical shape and has an inner wall that is a wall portion that accommodates a circuit element inside a cylinder. The inner wall has an outer shape without corners. The second member covers the inner wall from an outer peripheral surface side and closes an opening of the inner wall. The fixing member has a shape of a string and is arranged on an outer surface of a portion of the second member that covers the inner wall. The fixing member electrically connects the second member and the inner wall over an entire circumference.

Inventors

Takanori Uno
Masashi Inagaki

Assignees

DENSO CORPORATION

Dates

Publication Date: 20260512
Application Date: 20240222
Priority Date: 20230530

Claims (14)

1 . An electromagnetic shielding body, comprising: a first member including a wall portion, the wall portion having a cylindrical shape to thereby form a cylinder, and an opening and an outer shape without corners in a plan view in an axial direction, and accommodating a circuit element in the cylinder; a second member configured to cover the wall portion from an outer peripheral surface side and closes one opening of the wall portion; and a string-shaped fixing member disposed on an outer surface of a portion of the second member that covers the wall portion and configured to electrically connect the second member and the wall portion over an entire circumference.
2 . The electromagnetic shielding body according to claim 1 , wherein the first member is a cylindrical member whose both ends are open in the axial direction.
3 . The electromagnetic shielding body according to claim 2 , wherein the first member is mounted on a printed circuit board.
4 . The electromagnetic shielding body according to claim 1 , wherein the wall portion is a side wall with openings, the first member has a bottom wall that is continuous with the side wall and closes one of the openings of the side wall, and the second member is arranged at an end of the side wall opposite to the bottom wall.
5 . The electromagnetic shielding body according to claim 1 , wherein an outer shape of the wall portion is oval shape.
6 . The electromagnetic shielding body according to claim 1 , wherein the outer shape of the wall portion is a shape having no straight part.
7 . The electromagnetic shielding body according to claim 6 , wherein the outer shape of the wall portion is circular.
8 . The electromagnetic shielding body according to claim 1 , wherein the wall portion is an inner wall, the second member has an outer wall with openings arranged to surround the inner wall, and a ceiling wall that is continuous with the outer wall and closes one of the openings of the outer wall, and the outer wall has a shape similar to the outer shape of the inner wall in plan view.
9 . The electromagnetic shielding body according to claim 1 , wherein the second member is formed using cloth, a film, or a sheet.
10 . The electromagnetic shielding body according to claim 1 , wherein the fixing member has a screw type hose clamp that adjusts fixing strength.
11 . The electromagnetic shielding body according to claim 8 , wherein the second member has a concave portion or a convex portion that guides the fixing member on an outer peripheral surface of the outer wall.
12 . An electronic device, comprising: a circuit board having a printed board and an electronic component mounted on the printed board; and an electromagnetic shielding body configured to cover predetermined circuit elements on the circuit board, wherein the electromagnetic shielding body includes a first member including a wall portion, the wall portion having a cylindrical shape to thereby form a cylinder, and an opening and an outer shape without corners in a plan view in an axial direction, and accommodating a circuit element in the cylinder; a second member configured to cover the wall portion from an outer peripheral surface side and close an opening in the wall portion that is located away from the printed board, and a string-shaped fixing member disposed on an outer surface of a portion of the second member that covers the wall portion and configured to electrically connect the second member and the wall portion over an entire circumference.
13 . The electronic device according to claim 12 , wherein the first member has a plurality of legs extending from an end of the wall portion on the printed board side and provided at predetermined intervals over the entire circumference, and the printed board has a plurality of through holes into which the plurality of legs are individually inserted and mounted.
14 . The electronic device according to claim 13 , wherein the printed circuit board has a ground layer that provides a reference potential on a surface opposite to the surface on which the wall portion is arranged, and each of the legs is connected to the ground layer.

Description

CROSS REFERENCE TO RELATED APPLICATIONS The present application is based on Japanese Patent Application No. 2023-88791 filed on May 30, 2023, the description of which is incorporated herein by reference. TECHNICAL FIELD The present disclosure in this specification relates to an electromagnetic shielding body and an electronic device. BACKGROUND An electronic device includes a metal shield case. SUMMARY One of the objects of the present disclosure is to provide an electromagnetic shielding body and an electronic device that can enhance a shield effect with a simple configuration. An electromagnetic shielding body, which is one aspect of the disclosure, includes a first member that has a cylindrical shape, a wall portion having an outer shape with no corners in a plan view in an axial direction, and accommodates a circuit element in a cylinder, a second member that covers the wall portion from the outer peripheral surface side and closes one of the openings of the wall portion, and a string-shaped fixing member that is arranged on an outer surface of a part of the second member that covers the wall portion and electrically connects the second member and the wall portion over an entire circumference. BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a perspective view showing an electromagnetic shielding body and an electronic device according to a first embodiment; FIG. 2 is an exploded perspective view showing the electromagnetic shielding body and the electronic device; FIG. 3 is a cross-sectional view taken along a line III-III of FIG. 1; FIG. 4 is a plan view showing other example of a first member; FIG. 5 is a plan view showing other example of a first member; FIG. 6 is a plan view showing other example of a first member; FIG. 7 is a sectional view showing another example of a second member; FIG. 8 is a diagram showing an example of a fixing member; FIG. 9 is a diagram showing a relationship between a gap and a shield effect; FIG. 10 is a diagram showing a relationship between an electrical connection structure and a shield effect; FIG. 11 is a sectional view showing an electromagnetic shielding body according to a second embodiment; FIG. 12 is a sectional view showing another example of the second member; FIG. 13 is a plan view showing an electromagnetic shielding body and an electronic device according to a third embodiment; FIG. 14 is a sectional view taken along a line XIV-XIV in FIG. 13; and FIG. 15 is a cross-sectional view showing an electromagnetic shielding body and an electronic device according to a fourth embodiment. DETAILED DESCRIPTION An electronic device includes a metal shield case. A disclosure of JP 2022-75671 A is incorporated herein by reference as an explanation of the technical elements in this disclosure. A shield case includes a lower case with an opening on one side and a substantially rectangular planar shape 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 screws. In the case of such a configuration, the design is made such that surface contact can be made at locations other than those fixed by screws. However, due to manufacturing variations such as surface roughness and mounting variations, electrical connections at locations other than fixed locations are not reliable. A gap functions as a slot antenna, and there is a risk that, for example, electromagnetic noise may leak. In view of the above or other aspects not mentioned, there is a need for further improvements in an electromagnetic shielding body and an electronic device. One of the objects of the present disclosure is to provide an electromagnetic shielding body and an electronic device that can enhance a shield effect with a simple configuration. An electromagnetic shielding body, which is one aspect of the disclosure, includes a first member that has a cylindrical shape, a wall portion having an outer shape with no corners in a plan view in an axial direction, and accommodates a circuit element in a cylinder, a second member that covers the wall portion from the outer peripheral surface side and closes one of the openings of the wall portion, and a string-shaped fixing member that is arranged on an outer surface of a part of the second member that covers the wall portion and electrically connects the second member and the wall portion over an entire circumference. According to the disclosed electromagnetic shielding body, 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 to electrically connect them. Furthermore, since the outer shape of the wall portion does not have corners, the second member and the wall portion can be electrically connected over the entire circumference by tightening the fixing member. Therefore, the shield effect can be enhanced with a simple configuration. An electronic device acc