JPH0525279Y2 - - Google Patents

Description

[Detailed description of the invention] [Summary] The present invention improves mounting density and noise resistance in the electromagnetic shielding structure of a desktop electronic device that is equipped with a noise filter connected to the power cord inside the electromagnetic shielding structure housing. In order to improve the characteristics and facilitate disassembly and assembly, a mounting bracket is fixed to the inner wall of the rear panel mounted on the printed circuit board, and an electromagnetic wire is connected between the noise filter and the input and output lines of the noise filter. A shield cover for shielding noise is screwed to the mounting bracket, and the ground wire of the power cord and the ground wire of the noise filter are screwed to the mounting bracket.

[Industrial application field]

This invention relates to an electromagnetic shielding structure for desktop electronic devices.
More specifically, the present invention relates to an improvement in the electromagnetic shielding structure of a desktop electronic device that includes a noise filter connected to a power cord inside the casing.

In recent years, with the miniaturization of devices, desk-top electronic communication terminals, desk-top electronic information devices, etc. are increasing in office environments. As signal processing by these desktop electronic devices tends to become faster, it is necessary to strengthen electromagnetic shielding measures to prevent malfunctions due to noise.

In general, desktop electronic devices have a case structure that includes a printed board assembly consisting of a front plate and a rear plate mounted on a printed board, a bottom cover, and a ceiling cover, and the entire case is electromagnetically shielded. For construction purposes, the front and back plates are grounded to the bottom cover and ceiling cover. A power cord for supplying power to a desktop electronic device includes a ground wire and a power wire, and the power wire of the power cord is connected to a power circuit in the desktop electronic device via a noise filter. The noise filter includes an input line connected to a power line of a power cord, an output line connected to a power supply circuit via electrical parts such as fuses and switches, and a ground line. Furthermore, a shield cover for electromagnetic shielding between the input line and the output line of the noise filter is provided within the housing of the desktop electronic device.

In such a desk top electronic device, the ground wire of the power cord and the ground wire of the noise filter must each be grounded to the casing of the desk top electronic device. Furthermore, the shield cover for electromagnetic shielding between the input line and the output line of the noise filter needs to be grounded to the casing of the desktop electronic device.

When deciding on these earth connection structures, it is necessary to prevent as much as possible the deterioration of electricity, electronic component mounting space, circuit pattern formation space, etc. on the printed board due to electromagnetic shielding parts and earth connection parts, and also to It is necessary to improve noise resistance by reducing contact resistance as much as possible. Furthermore, it is necessary to have a structure that allows easy disassembly and assembly of electromagnetic shielding parts and grounding parts.

[Conventional technology]

Figure 4 shows the housing structure of a typical desktop electronic device such as a desktop electronic communication terminal, and Figure 5 shows the conventional electromagnetic shielding structure adopted in the housing structure shown in Figure 4. This is what is shown.

First, referring to FIG. 4, the desktop electronic device includes a printed board assembly 1 constructed by assembling a front plate 3 and a rear plate 4 onto a printed board 2 on which electronic components (not shown) are mounted, and a bottom cover 5. and a ceiling cover 6.

The front plate 3 and rear plate 4 are attached to the printed board 2 with screws 7.
The printed board assembly 1 is fixed to the screw 8.
is fixed to the bottom cover 5 and the ceiling cover 6
is fixed to the bottom cover 5 with screws 9. Further, the bottom cover 5 is maintained in electrical continuity with the front plate 3 and rear plate 4 by screws 8, and the ceiling cover 6 is maintained in a conductive state with the front plate 3 and rear plate 4 by earth spring plates 10 and 11 fixed to the front plate 3 and rear plate 4. Thus, the front plate 3 and the rear plate 4 are maintained in a conductive state. The above connection structure allows the entire casing to be grounded. In FIG. 4, 12 is a metal fitting into which the screw 7 is screwed, 13 is a bush into which the screw 8 is screwed, and 14 is a metal fitting into which the screw 9 is screwed. In addition, 15 is an external line connector, 16
is a jack, and 17 is an indicator light (LED).

As shown in FIG. 5, the end of a power cord 18 is fixed to the rear plate 4 of the printed board assembly 1 by a cord holder 19. As shown in FIG. The power cord 18 has a ground wire 20 and a power wire 21, and the ground wire 20 is connected to the metal fitting 12 of the rear plate 4 by a screw 8 via a crimp terminal 22. . On the other hand, a power line 21 of the power cord 18 is connected to an input line 24 of a noise filter 23, and an output line 25 of the noise filter 23 is connected to electrical components such as fuses and switches (not shown).

The noise filter 23 has metal fittings 26 at both ends, and the noise filter 23 is fixed onto the printed board 2 by screws 27 passed through the metal fittings 26 and nuts 28. Further, a connecting fitting 29 is fixed to one fitting 26 of the noise filter 23 with a screw 27 and a nut 28 to electromagnetically shield between the input line 24 and the output line 25 of the noise filter 23. The shield cover 30 is fixed to the connecting fitting 29 with screws 31 on one side, and to the rear plate 4 with screws 32 on the other side. Ground wire 33 coming out from noise filter 23
is fixed to a connecting fitting 29 with a screw 27 and a nut 28.

[Problem that the invention attempts to solve]

In the electromagnetic shielding structure of the conventional desktop electronic device described above, the metal fitting 26 of the noise filter 23 is screwed onto the printed board 2, and the shield cover 30 covering the noise filter 23 covers the printed board 2. Therefore, the noise filter 23 and the shield cover 30 have a disadvantage in that the mounting space for other electrical and electronic components and the space for forming circuit patterns on the printed board 2 are limited by the noise filter 23 and the shield cover 30.

In addition, since the ground wire 33 of the noise filter 23 is grounded to the rear plate 4 via the connection fitting 29 and the shield cover 30, the contact resistance in the grounding path increases, the grounding effect decreases, and the noise resistance characteristics deteriorate. There was a drawback that it deteriorated.

Furthermore, in the conventional electromagnetic shielding structure, when it is necessary to remove the noise filter 23 during maintenance, in order to remove the screw 27, it is necessary to remove the screw 8 and remove the bottom cover 5 from the printed board assembly 1. , disassembly and assembly were time-consuming.

[Problem that the invention attempts to solve]

In this invention, an electromagnetic shielding case is constructed by attaching a bottom cover and a ceiling cover to the front plate and rear plate mounted on a printed circuit board, and a power cord having a power line and a ground wire is attached to the rear plate. Screw a noise filter that has an input line, an output line, and a ground line to a mounting bracket that is fixed and electrically connected to the inner wall, connect the input line of the noise filter to the power line of the power cord, and then connect the noise filter's output line to the power line of the power cord. Connect the wire to the power circuit inside the housing, screw the power cord's ground wire and the noise filter's ground wire to the mounting bracket, and install a shield cover for electromagnetic shielding between the noise filter's input line and output line. Provided is an electromagnetic shielding structure for a desktop electronic device that is screwed onto a mounting bracket.

[Effect]

In the electromagnetic shielding structure of the desktop electronic device according to the present invention, the noise filter and the shield cover are separated from the printed board and screwed to the mounting bracket fixed to the rear board, so that electrical and electronic components can be mounted on the printed board. The space and circuit pattern formation space are no longer restricted by noise filters and shield covers, making it possible to increase the packaging density of electrical and electronic components.

On the other hand, the ground wire of the power cord, the ground wire of the noise filter, and the shield cover are grounded to the rear panel by screwing them to the mounting bracket, which simplifies the grounding path and reduces the contact resistance in the grounding path. This improves noise resistance.

Furthermore, the noise filter and shield cover are screwed to the mounting bracket fixed to the rear panel, so if it is necessary to remove the noise filter, there is no need to remove the bottom cover from the printed board. installation can be carried out. Therefore, operations such as disassembling and assembling the desktop electronic device become easier.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

1 to 3 show an embodiment of the present invention. Referring to these figures, the desktop electronic device includes a printed board 52 on which electrical and electronic components (not shown) are mounted, and a front plate (not shown) and a rear board mounted on the front and rear ends of the printed board 52, respectively. 53, a bottom cover 54, and a ceiling cover 55.
It is equipped with The front plate and rear plate 53 are screwed 5
6 is screwed to the printed board 52,
The printed board 52 is screwed to the bottom cover 54 with screws 57, and the ceiling cover 55 is screwed to the bottom cover 54 with screws not shown. These screw-fastening structures are the same as the screw-fastening structure in a general desktop electronic device shown in FIG. The front plate, the rear plate 53, the bottom cover 54, and the ceiling cover 55 are each made of a metal plate, and
They are maintained in a conductive state by mutual fixing screws, forming a housing with an electromagnetic shielding structure.

The end of a power cord 58 having a power line 59 and a ground connection 60 is attached to the rear plate 5 by a cord holder 61.
It is fixed at 3.

A mounting bracket 62 is fixed and electrically connected to the inner wall of the rear plate 53 by, for example, welding. A noise filter 63 having an input line 64, an output line 65, and a ground line 66 has metal fittings 67 integrated at both ends.
The noise filter mounting portions 62a and 62b of the mounting bracket 62 are screwed to the noise filter mounting portions 62a and 62b of the mounting bracket 62 by screws 68 passed through the holes 7 and 68, respectively.

The input line 64 of the noise filter 63 is connected to the power line 59 of the power cord 58, and the output line 65 of the noise filter 63 is connected to the inside of the casing via electrical parts such as fuses and switches (not shown). connected to the power supply circuit.

The ground wire 60 of the power cord 58 is connected and fixed to the ground wire mounting portion 62c of the mounting bracket 62 with a screw 69, and the ground wire 60 of the noise filter 63
6 is fixed in contact with the noise filter mounting portion 62b of the mounting bracket 62 together with the metal fitting 7 by screws 68.

On the other hand, a shield cover 70 for electromagnetically shielding between the input line 64 and the output line 65 of the noise filter 63 is screwed to the cover mounting portions 62d and 62e of the mounting bracket 62 with screws 71 and 72. The shield cover 70 has a notch 70a that engages with the noise filter 63 and the noise filter attachment portion 62a of the attachment fitting 62. When the shield cover 70 is screwed to the mounting bracket 62,
The output line 65 of the noise filter 63 is located outside the shield cover 70. On the other hand, power cord 58
The input line 64 of the noise filter 63 of the power supply line 59 of
is surrounded by the shield cover 70 and electromagnetically shielded.

In the electromagnetic shielding structure of the desktop electronic device having the above configuration, the noise filter 63 and the shield cover 70 are separated from the printed board 52 and screwed to the mounting bracket 62 fixed to the rear panel 53. The mounting space for electrical and electronic components and the circuit pattern forming space are no longer restricted by the noise filter 62 and the shield cover 70. Therefore, the mounting density of electrical and electronic components on the printed board 52 can be increased.

On the other hand, the ground wire 60 of the power cord 58, the ground wire 66 of the noise filter 63, and the shield cover 70 are grounded to the rear plate 53 by being screwed to the mounting bracket 62, so the grounding path is simplified and the grounding Contact resistance within the path is reduced. Therefore, the noise resistance against static electricity and the like of the internal circuit of the desktop electronic device is improved.

Further, since the noise filter 63 and the shield cover 70 are screwed to a mounting bracket 62 fixed to the rear panel 53, if it is necessary to remove the noise filter 63 for maintenance etc., it is necessary to remove the noise filter 63 from the bottom part from the printed board 52. The noise filter 63 can be removed and attached without having to remove the cover 54. Therefore, disassembly of tabletop electronic devices,
Work such as assembly becomes easier.

Although the illustrated embodiments have been described above, the present invention is not limited to the embodiments described above. For example, changes can be made to the shape of the mounting bracket and the locations where the noise filter, shield cover, ground wire, etc. are screwed to the mounting bracket.

[Effect of idea]

As is clear from the above description, according to the present invention, the noise filter and shield cover can be separated from the printed board, which increases the mounting space for electrical and electronic components and the space for forming circuit patterns on the printed board. This makes it possible to increase the packaging density of electrical and electronic components.

In addition, since the power cord's earth wire, the noise filter's earth wire, and the shield cover can be earthed to the rear panel via only the mounting brackets, the noise resistance of the desktop electronic device can be improved by simplifying the earth path.

Furthermore, since the noise filter and shield cover are screwed to the mounting bracket fixed to the rear panel,
If it is necessary to remove the noise filter, the noise filter can be removed and installed without having to remove the bottom cover from the printed circuit board. Therefore, operations such as disassembling and assembling the desktop electronic device become easier.

Therefore, according to the present invention, it is possible to provide an electromagnetic shielding structure for a desktop electronic device that enables high-density packaging, improves noise resistance, and is easy to disassemble and assemble.

[Brief explanation of drawings]

FIG. 1 is a plan view of a main part of an electromagnetic shielding structure for a desktop electronic device showing an embodiment of the present invention, FIG. 2 is a partially sectional side view of a main part of the electromagnetic shielding structure shown in FIG. 1, and FIG.
The figure is an exploded perspective view of the electromagnetic shielding structure shown in Figure 1, Figure 4 is an exploded perspective view showing the housing structure of a general desktop electronic device, and Figure 5 is a main part of the electromagnetic shielding structure of a conventional desktop electronic device. FIG. In the figure, 52 is a printed board, 53 is a rear panel, 54 is a bottom cover, 55 is a ceiling cover, and 58
is the power cord, 59 is the power wire of the power cord, 60
is the ground wire of the power cord, 62 is the mounting bracket, 63
64 represents a noise filter, 64 represents an input line of the noise filter, 65 represents an output line of the noise filter, 66 represents a ground wire of the noise filter, and 70 represents a shield cover.

Claims (1)

[Scope of Claim for Utility Model Registration] A power source comprising an electromagnetic shielding case by attaching a bottom cover 54 and a ceiling cover 55 to a front plate and a rear plate 53 mounted on a printed board 52, and having a power line 59 and a ground line 60. A cord 58 is attached to the rear plate 53, and a noise filter 63 having an input line 64, an output line 65, and a ground line 66 is screwed to a mounting bracket 62 that is fixed and electrically connected to the inner wall of the rear plate 53 to eliminate noise. Connect the input line 64 of the filter to the power line 59 of the power cord, and connect the output line 65 of the noise filter.
is connected to the power supply circuit inside the housing, and the ground wire 60 of the power cord and the ground wire 66 of the noise filter are screwed to the mounting bracket 62 to provide electromagnetic shielding between the input wire 64 and the output wire 65 of the noise filter. An electromagnetic shielding structure for a tabletop electronic device in which a shield cover 70 is screwed to a mounting bracket 62.