JPH0412706Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a casing structure for an electronic device that is particularly suitable as a casing structure for a high frequency circuit section in a radio device or the like.

[Technical background of the invention] In electronic devices that use high-frequency circuits such as in-vehicle radios, printed wiring boards on which electronic components are mounted are made of metal to prevent the intrusion of external radio waves and the leakage of radio waves to the outside. It is necessary to cover it with a casing, and it is also necessary to reliably electrically connect the ground pattern of the printed wiring board and the casing to prevent parasitic oscillations from occurring due to stray capacitance or the like.

FIGS. 4 and 5 show conventional housing structures used in this type of electronic equipment.

In the figure, 1 is a housing of an electronic device. Housing 1 is
It is composed of a main body 2 and a cover 3, and these main body 2 and cover 3 are formed by die-casting.

A groove 5 is formed in the end 4 of the cover 3 that is joined to the main body 2 so as to surround the inside of the cover 3, and a metal mesh 6 is inserted into the groove 5. This metal mesh 6 is formed by covering silicone rubber with a metal mesh, and has sufficient elasticity. Therefore, when the cover 3 is fixed to the main body 2 with the screws 8 with the end 4 of the cover 3 in contact with the end 7 of the main body 2, the metal mesh 6 is securely attached to the ends 4 and 7. The cover 3 and the main body 2 are brought into close contact with each other, and the cover 3 and the main body 2 are electrically connected reliably.

8 is a printed wiring board. The printed wiring board 8 is the main body 2
It is fixed with a screw 10 to a boss 9 formed in the. Then, by attaching the cover 3 to the main body 2, the printed wiring board 8 is covered with the housing 1.
Therefore, the printed wiring board 8 is protected from external moisture, dust, and even the influence of radio waves. Further, the ground pattern 11 of the printed wiring board 8 is electrically connected to the main body 2 via the screw 10, and therefore the ground pattern 11 and the entire casing 1 are electrically connected.

[Problems in the Background Art] However, in the conventional case structure described above, although the electrical connection between the main body 2 and the cover 3 is sufficiently ensured by the metal mesh 6, the printed wiring board 8 The electrical connection between the ground pattern 11 and the casing 1 relies on the screws 10, and it has not been possible to ensure sufficient electrical connection between the two. Therefore, there were problems such as a tendency for the ground potential difference between the ground pattern 11 and the housing 1 to become large, and for parasitic oscillation to occur easily. In addition, in order to ensure electrical connection between the ground pattern 11 and the housing 1, screws 1 necessary for attaching the printed wiring board 8 to the main body 2 are required.
Attach more screws 10 than number 0. Alternatively, since it is necessary to use a method such as connecting the ground pattern 11 and the casing 1 using a metal piece, these methods have the problem of increasing the number of parts and the number of assembly steps.

[Purpose of the invention] The present invention was made in view of the above-mentioned drawbacks of the conventional technology, and provides a reliable electrical connection between the earth pattern of the printed wiring board and the casing without increasing the number of parts or the number of assembly steps. The purpose of the present invention is to provide a housing structure for an electronic device that can be obtained.

[Summary of the invention] In the case structure of the invention, a recess is formed at one end of the main body and the cover, and the other end has a print on the side opposite to the surface on which the ground pattern is formed. A stepped portion is formed having a first surface that is in contact with the surface of the wiring board and a second surface that protrudes toward the printed wiring board side from the first surface, and an end surface of the one end portion. By sandwiching the peripheral edge of the printed wiring board between the first surface of the stepped portion and the ground pattern of the printed wiring board and the second surface of the stepped portion, the elastic conductive member inserted into the recessed portion The above objective is achieved by having a structure in which the two are in contact with each other.

[Embodiments of the invention] Hereinafter, embodiments of the invention will be described in detail with reference to FIGS. 1 to 3.

In the figure, 20 is a housing of the electronic device. Housing 20
is composed of a main body 21 and a cover 22, and these main body 21 and cover 22 are formed by die-casting.

A groove (recess) 24 is formed in the end 23 of the cover 22 that joins the main body 21 so as to surround the inside of the cover 22.
As in the conventional example, a metal net 25 is inserted as an example of an elastic conductive member, but the present invention is not limited to this, and conductive rubber or a metal net hardened with rubber may be used. On the other hand, the end 2 of the main body 21 that joins the end 23
6 includes a stepped portion 2 so as to surround the inside of the main body 21.
7 is formed.

29 is a printed wiring board. A ground pattern 30 is formed on the periphery of the printed wiring board 29.
This printed wiring board 29 is fixed to a boss 31 of the main body 21 with screws 32. In this case, printed wiring board 29
The peripheral edge thereof is the lower first surface 3 of the stepped portion 27.
3, and the ground pattern 30 is located on the upper second surface 3 of the stepped portion 27.
It is positioned so that it is almost flush with 4. on the other hand,
The recess 24 and step 27 are positioned such that when the cover 22 is fixed to the main body 21 with screws 35, the upper side 34 and lower side 33 of the step 27 face the recess 24.

Since this embodiment has the above-described configuration, when the printed wiring board 29 is fixed to the main body 21 with the ground pattern 30 facing upward, and the cover 22 is fixed to the main body 21, the peripheral edge of the printed wiring board 29 is The ground pattern 30 is sandwiched between the end surface 37 of the metal net 23 and the lower surface 33 of the stepped portion 27, and the ground pattern 30 is securely in contact with the metal net 25. Further, the upper surface 34 of the stepped portion 27 also comes into contact with the metal mesh 25 (FIG. 3). Therefore, the main body 21, the cover 22 and the ground pattern 3
0 is grounded at one point with the metal net 25,
The difference in ground potential between the ground pattern 30 and the housing 20 becomes extremely small.

In addition, in this example, the recessed part 24 and the stepped part 27 are
They are provided to surround the cover 22 and the main body 21, respectively.
This is to prevent radio waves from entering the inside of the housing 20 or from leaking from inside the housing 20. If the purpose of the housing of an electronic device is to reduce the ground potential difference, provide a recess or step in one or several places on the main body and cover, so that the main body, cover, and ground pattern can be grounded at one or several places. It is also possible to have a configuration in which they are connected.

[Effects of the invention] As explained above, the casing structure of the invention has the following effects:
The ground patterns of the main body, cover, and printed wiring board are grounded at one point using a conductive member.
Therefore, the difference in ground potential between the casing and the ground pattern can be reduced without increasing the number of parts or the number of assembly steps compared to the conventional case.

[Brief explanation of the drawing]

1 to 3 are diagrams explaining an embodiment of the present invention, and FIG. 2 is an exploded perspective view of the housing structure;
The figure is a cross-sectional view taken along the line -- in FIG. 2 with the casing assembled, and FIG. 3 is an enlarged view of the circle in FIG. 1. FIG. 4 is an exploded perspective view showing the conventional housing structure.
Figure 5 is the same as Figure 4 with the casing assembled.
FIG. 20... Housing, 21... Main body, 22... Cover, 23... (One) end, 24... Recess, 2
5... Metal mesh, 26... (other) end, 27...
...Stepped part, 29...Printed wiring board, 30...Earth pattern, 33...Bottom side (of step), 34...
Upper surface (of the stepped portion), 37... end surface (of one end).

Claims (1)

[Scope of utility model registration request] A printed wiring board having a ground pattern formed on at least a part of its periphery is covered with a conductive main body and a cover, and the ground pattern of the printed wiring board is electrically connected to the main body and cover. The housing structure of the device is such that one end of the main body and the cover is formed with a recess in which an elastic conductive member is provided, and the other end is provided with a recess that is provided with an opposite surface of the printed wiring board. A stepped portion has a first surface that is in contact with a surface opposite to the surface on which the ground pattern is formed, and a second surface that protrudes toward the printed wiring board side from the first surface. a peripheral edge portion of the printed wiring board is sandwiched between the end surface of the one end portion and the first surface in a state in which the ground pattern and the second surface are in contact with the conductive member; A housing structure for an electronic device featuring: