The present invention relates to a magnetic shield structure, and particularly a magnetic shield structure formed by performing metal plating on a housing.
As an example of a magnetic shield structure, there has been a high-frequency relay that is magnetically shielded by fitting a separate metal case to a relay body and covering the entire relay body (Patent Document 1).
Patent Document 1: Japanese Unexamined Patent Publication No. 2000-340084
However, the high-frequency relay is made up by covering, with the metal case, the relay body formed by covering a body with a cover. Hence the high-frequency relay requires the separate metal case, the number of parts and the number of assembling steps are large, and the productivity is low.
Further, external dimensions of the metal case and the positional relationship between the metal case and a high-frequency transmission component affect high-frequency characteristics. For this reason, high dimensional accuracy and assembly accuracy are required in manufacturing and assembling the metal case, and the manufacturing and the assembly are thus not easy.
The metal case covers the entire exposed surface, except for the installation surface, of the relay body. This leads to a problem in which desired high-frequency characteristics cannot be obtained due to the metal case covering an unnecessary region and a region that causes deterioration in characteristics of a transmission path structure.
In view of the above problems, an object of the present invention is to provide a magnetic shield structure having high productivity and excellent high-frequency characteristics, and easy to manufacture and assembly.
For solving the above problem, a magnetic shield structure according to the present invention is partially provided with a magnetic shield body, formed by metal plating, on at least one of an outer surface and an inner surface that form the surface of a housing made of a dielectric material.
According to the present invention, since the magnetic shield body is provided directly on the housing, it is possible to obtain a magnetic shield structure having high productivity with smaller numbers of parts and assembling steps.
Also, a magnetic shield body is formed directly in a region that requires the housing. Hence it is possible to prevent deterioration in high-frequency characteristics based on the variations of the dimensional accuracy and the assembly accuracy in the housing.
Then, a magnetic shield body is formed only in a region that requires the housing. Therefore, as in the conventional example, the magnetic shield body is not formed in an unnecessary region or a region that causes deterioration in characteristics of a transmission path structure. As a result, the effect of obtaining a magnetic shield structure with excellent high-frequency characteristics is provided.
25 viewed from a different angle.
A magnetic shield structure according to an aspect of the present invention is partially provided with a magnetic shield body, formed by metal plating, on at least one of an outer surface and an inner surface that form a surface of a housing made of a dielectric material.
According to this aspect, since the magnetic shield body is provided directly on the housing, it is possible to obtain a magnetic shield structure having high productivity with smaller numbers of parts and assembling steps.
Also, a magnetic shield body is formed directly in a region that requires the housing. Hence it is possible to prevent deterioration in high-frequency characteristics based on the variations of the dimensional accuracy and the assembly accuracy in the housing.
Then, a magnetic shield body is formed only in a region that requires the housing. Therefore, as in the conventional example, the magnetic shield body is not formed in an unnecessary region or a region that causes deterioration in characteristics of a transmission path structure. As a result, the effect of obtaining a magnetic shield structure with excellent high-frequency characteristics is provided.
In the magnetic shield structure according to the aspect of the present invention, the magnetic shield body may be formed by the metal plating in a region facing high-frequency transmission path disposed in the housing on the inner surface and/or the outer surface of the housing, such that a characteristic impedance of the high-frequency transmission path becomes uniform.
According to this aspect, it is unnecessary to always provide the magnetic shield body by metal plating on the entire inner surface and/or outer surface of the housing. Hence it is possible to save a raw material and obtain a magnetic shield structure with high productivity.
In a magnetic shield structure according to another aspect of the present invention, the magnetic shield body may be formed by the metal plating and a dielectric in a region facing the high-frequency transmission path disposed in the housing on the inner surface and/or the outer surface of the housing, such that a characteristic impedance of the high-frequency transmission path becomes uniform.
According to this aspect, it is unnecessary to always provide the magnetic shield body by metal plating and a dielectric on the entire inner surface and/or outer surface of the housing. Hence it is possible to save a raw material and obtain a magnetic shield structure with high productivity.
In a magnetic shield structure according to another aspect of the present invention, the housing may be made up of a base and a case fitted to the base.
According to this aspect, a highly versatile magnetic shield structure can be obtained.
In a magnetic shield structure according to a new aspect of the present invention, the magnetic shield body may be formed on at least a part of an outer surface of the case Further, the magnetic shield body may be formed on at least a part of the inner surface of the case.
According to this aspect, since the magnetic shield body can be formed in a necessary region as necessary, it is possible to obtain a magnetic shield structure having more excellent high-frequency characteristics.
In a magnetic shield structure according to another aspect of the present invention, the magnetic shield body formed on the outer surface of the case and the magnetic shield body formed on the inner surface of the case may be electrically connected by the metal plating.
According to this aspect, it is possible to obtain a magnetic shield structure having more excellent high-frequency characteristics.
In a magnetic shield structure according to another aspect of the present invention, the magnetic shield body may be provided on at least a part of a bottom surface of the base.
According to this aspect, since the magnetic shield body can be formed in a necessary region as necessary, a magnetic shield structure having a wide application can be obtained.
In a magnetic shield structure according to a new aspect of the present invention, the magnetic shield body formed on the outer surface of the case and the magnetic shield body formed on the bottom surface of the base may be electrically connected by the metal plating.
According to this aspect, it is possible to connect to the ground via the magnetic shield body provided on the bottom surface of the base.
In a magnetic shield structure according to another aspect of the present invention, the housing may be made up of a plug body and a socket body connected to the plug body.
According to this aspect, a highly versatile magnetic shield structure can be obtained.
In a magnetic shield structure according to another aspect of the present invention, the magnetic shield body may be formed by the metal plating on at least a part of the plug body. In addition, the magnetic shield body may be formed by the metal plating on at least a part of the socket body.
According to this aspect, there is an effect that a magnetic shield structure can be formed in a necessary region as necessary.
An electric/electronic component according to an aspect of the present invention includes the above magnetic shield structure.
According to this aspect, the magnetic shield structure is not limited to electromagnetic relays, switches, and connectors, and can be applied to other electric devices and electronic components having a high-frequency transmission component in a housing made of resin.
Embodiments of a magnetic shield structure according to the present invention will be described with reference to
In a first embodiment, as illustrated in
As illustrated in
For convenience of description, a magnetic shield body 50 provided in the case 40 is illustrated in a dotted pattern.
As illustrated in
As illustrated in
As illustrated in
Then, as illustrated in
The case 40 is a resin molded product having a box shape that can be fitted to the base 11. The magnetic shield body 50 is formed on the outer peripheral surface of the case 40 by a molded interconnect devices (MID) molding method. In the MID molding method, laser irradiation is performed on a molded article formed from a material in which a resin and a conductive material are mixed, based on a predetermined pattern, and the resin is removed. Then, metal plating is performed on the exposed conductive material so as to form a desired circuit pattern. A tubular magnetic shield portion 51 is also provided on the entire surface of a terminal portion 41 extending from the opening edge of the case 40 (
The magnetic shield body 50 is provided based on the knowledge that high-frequency signals tend to leak if the characteristic impedance varies in the high-frequency transmission path. Therefore, in order to reduce the leakage of the high-frequency signal, the magnetic shield body 50 is formed so as to reduce variations in the characteristic impedance in the high-frequency transmission path.
In short, instead of forming the magnetic shield body by metal plating over the entire outer peripheral surface of the case 40, a suitable magnetic shield body 50 is formed in a necessary region. As a result, the magnetic shield body 50 constitutes, for example, a microstrip structure, a strip line structure, and a coplanar line structure.
The region where the magnetic shield body 50 is formed may be a region facing the high-frequency transmission path installed in the housing among the inner surface and/or the outer surface of a housing formed of a base and a case.
More specifically, it is preferable to arrange and form metal plating and/or dielectric so that the characteristic impedance of the high-frequency transmission path becomes uniform. It is a matter of course that air is also considered as a dielectric.
For example, it is preferable to arrange and form the metal plating and/or the dielectric so that the characteristic impedance in each region of the high-frequency transmission path is equal to the reference value of 50 Ω. This is because if there is a difference in characteristic impedance for each region of the high-frequency transmission path, high frequency leaks easily from the boundary of the region where the difference is present, and the high-frequency characteristics are degraded.
As the microstrip structure in this embodiment, for example, as illustrated in
Further, as a strip line structure, for example, as illustrated in
As a coplanar line structure, for example, as illustrated in
Next, a method of operating a self-holding type electromagnetic relay having the above-described configuration will be described.
For example, when no voltage is applied to the coil 22 of the electromagnet block 20 illustrated in
When a voltage is applied to the coil 22 so as to generate a magnetic line of force in a direction canceling the magnetic lines of force of the permanent magnet 32 illustrated in
Subsequently, even when the application of the voltage to the coil 22 is stopped, the movable block 30 keeps its state by the magnetic force of the permanent magnet 32.
Finally, a voltage in a direction opposite to the above-mentioned voltage application direction is applied to the coil 22 illustrated in
Thereafter, the contacts are switched by repeating the same operation.
The high-frequency characteristics of the electromagnetic relay provided with the magnetic shield body 50 according to the embodiment were analyzed. The analysis result is illustrated in the graph of
As a comparative example, there was used a case where a metal case covering the entire case was covered without forming a magnetic shield body of metal plating on the case of the same electromagnetic relay as in the first embodiment. The other high-frequency characteristics were analyzed on the same conditions as in the first embodiment described above. The analysis result is illustrated in the graph of
The high-frequency characteristics are measured by time domain reflectometry (TDR) method in
“(A) Terminal portion” indicates a characteristic impedance of only a distal region of the common terminal 17 in
“(B) Fixed contact terminal” indicates a characteristic impedance in a region from a boundary of the distal region to the common connection receiver 16 in the common terminal 17.
“(C) Movable touch piece” indicates a characteristic impedance in a region from the base of the connecting tongue piece 34 of the movable touch piece 33 to the movable contact 36.
“(D) Fixed contact terminal” indicates a characteristic impedance in a region from the fixed contact 14 of the fixed contact terminal 15 provided on the fixed contact terminal 15 to a boundary of a distal region surface-mounted on the printed circuit board.
“(E) Terminal portion” indicates a characteristic impedance of only a distal region of the fixed contact terminal 15 which is surface-mounted on the printed circuit board.
As is apparent from
In a second embodiment, as illustrated in
The magnetic shield body 60 is provided at each corner portion facing the inner peripheral surface of the case 40. In particular, as illustrated in
According to the embodiment, as illustrated in
Therefore, according to the second embodiment, not only the magnetic shield body 50 but also the magnetic shield body 60 is provided, whereby the characteristic impedance can be easily adjusted. For this reason, the variation in the characteristic impedance in the high-frequency transmission path is more easily reduced, and the high-frequency characteristics can be improved. There is thus an advantage that the degree of design freedom is widened to further expand the application.
In a third embodiment, as illustrated in
As illustrated in
The box-shaped case 80 has a box shape capable of covering the upper surface of the plate-shaped base 71, and an operation hole 81 is formed on the ceiling surface. In addition, the box-shaped case 80 has a magnetic shield body 91 having an annular shape and formed on its outer surface by the MID molding method. The magnetic shield body 91 is electrically connected to the magnetic shield body 90 via a connecting portion 92. Therefore, the magnetic shield body 91 can be connected to the ground via the magnetic shield body 90 covering the positioning legs 76 of the plate-shaped base 71.
As illustrated in
Therefore, by sliding the operation protrusion 102 of the operation lever 100, the movable contacts 106, 107 come into contact with the fixed contacts 74, 75, respectively. Even when a high frequency signal flows to the fixed contact terminal 72, the movable touch piece 105 and the fixed contact terminal 73, it is magnetically shielded by the magnetic shield bodies 90, 91. There is thus an advantage that not only leakage of high frequency signals but also entry of external signals can be prevented.
In a fourth embodiment, as illustrated in
The plug 110 is formed by integrally molding three connecting pins 112, 113, 114 disposed side by side into a plug body 111 formed of resin serving as a dielectric. A magnetic shield body 120 is formed on the plug body 111 by the MID molding method.
That is, in the magnetic shield body 120, an upper piece portion 121 and a lower piece portion 122 which are disposed so as to sandwich the connecting pins 112, 113, 114 from above and below, are electrically connected by a connecting portion 123. The connecting portion 123 is electrically connected to the connecting pin 114 connected to the ground.
Further, the socket 130 is formed by integrally molding three receiving pins 132, 133, 134 disposed side by side into a socket body 131 formed of resin serving as a dielectric. In the socket body 131, a magnetic shield body 140 is formed by the MID molding method.
That is, in the magnetic shield body 140, an upper piece portion 141 and a lower piece portion 142 which are formed so as to sandwich the receiving pins 132, 133, 134 from above and below, are electrically connected by a connecting portion 143. The connecting portion 143 is electrically connected to the receiving pin 134 connected to the ground.
A magnetic shield structure according to the present invention is not limited to the electromagnetic relay, the switch, and the connector described above, and may be applied to other electric devices and electronic components having a high-frequency transmission component in a housing made of resin.
10 electromagnetic relay
11 base
12 fixed contact
13 fixed contact terminal
14 fixed contact
15 fixed contact terminal
16 common connection receiver
17 common terminal
18 coil terminal
20 electromagnet block
21 iron core
22 coil
23 spool
30 movable block
31 movable iron piece
32 permanent magnet
33 movable touch piece
40 case
41 terminal portion
50 magnetic shield body
51 tubular magnetic shield portion
60 magnetic shield body
61 arm
62 leg
70 switch
71 plate-shaped base
72 fixed contact terminal
73 fixed contact terminal
74 fixed contact
75 fixed contact
76 positioning leg
80 box-shaped case
81 operation hole
90 magnetic shield body
91 magnetic shield body
92 connecting portion
110 plug
111 plug body
120 magnetic shield body
121 upper piece portion
122 lower piece portion
123 connecting portion
130 socket
131 socket body
140 magnetic shield body
141 upper piece portion
142 lower piece portion
143 connecting portion
Number | Date | Country | Kind |
---|---|---|---|
2015-179234 | Sep 2015 | JP | national |
Number | Date | Country | |
---|---|---|---|
Parent | PCT/JP2016/075114 | Aug 2016 | US |
Child | 15876069 | US |