JP2000278202A - Base station wireless unit - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To realize a shield structure for electromagnetic waves, a ground structure for electronic components housed therein, and a shield structure not affected by environmental changes with a reasonable structure with a small number of parts and easy assembly. A wireless unit for a base station is provided. SOLUTION: When a substrate 25 is covered with a pair of shield plates 22 and 23 from the front and back sides, shield ribs 28 and 29
(5) The electronic components are shielded by contacting the front and back surfaces. Moreover, the board 25 is shielded from other wireless units. In addition, the electronic components on the substrate 25 are
To earth. Further, since the fastening of the shield plates 22 and 23 is performed by fastening the fastening flange portions f1 and f2 with the shield plate fastening screws 24 having the short screw portions 24a, even if the environmental temperature of the wireless unit repeatedly changes. The fastening part is not easily loosened, resulting in a shield structure that is not affected by environmental changes.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a base station radio unit used in a radio communication system such as a pager system or a portable telephone system, and more particularly, to a shield structure for electromagnetic waves, a ground structure for electronic components housed therein,
The present invention relates to a base station wireless unit that realizes a shield structure that is not affected by environmental changes with a reasonable structure that has a small number of parts and is easy to assemble.

[0002]

2. Description of the Related Art For example, in a portable telephone system, a base station is installed in each area of a predetermined size, and wireless communication is performed with a portable telephone in the area. Such a base station is provided with a wireless unit for performing wireless communication. However, in recent years when mobile phones have become popular, one base station is provided with a plurality of wireless units and a large number of mobile phones are provided. We can accommodate subscribers. The plurality of wireless units are collectively housed in, for example, a dedicated rack and provided in a base station, and each of the wireless units is forcibly air-cooled by a fan unit provided at a lower portion of the rack. I have.

Here, such a wireless unit prevents unnecessary electromagnetic wave coupling with another wireless unit,
In order to make the impedance constant and exhibit the desired performance, an electromagnetic wave shield must be provided. Also,
Various electronic components such as an electronic component forming a wireless unit and an electronic component forming a transmitting / receiving unit are accommodated in the wireless unit. As a result, an electromagnetic wave shield must be provided in order to prevent unnecessary electromagnetic wave coupling between the electronic components even inside the wireless unit, to stabilize the impedance, and to exhibit the intended performance. Furthermore, in such a wireless unit, a ground must be provided to prevent malfunction of the electronic components housed therein, and an amplifier circuit for amplifying a transmission / reception signal is housed as an electronic component. In order to efficiently cool the amplifying circuit that generates heat, a heat sink must be provided on the outer surface of the wireless unit.

The wireless unit must have a structure that satisfies these various requirements, and the conventional wireless unit has a structure as shown in FIGS. FIG. 12 shows the appearance of the wireless unit in plan view, and FIG.
3 shows the wireless unit in a section taken along the line A1-A1 in FIG. 12, FIG. 14 shows the wireless unit in a section viewed in plan, FIG. 15 shows the wireless unit in a section taken along the line B1-B1 in FIG. FIG. 16 shows the wireless unit in a cross section taken along the line C1-C1 in FIG.

[0005] As shown in the figure, a radio unit is provided with a heat sink plate 2 on which a cooling fin 1 is formed and a shield plate 3 having a box shape formed by opening one side, and the case is mounted by screws 4 from the side. This has a structure in which a substrate on which various electronic components are mounted is housed, and a shield plate 3 electromagnetically shields from other wireless units. Then, the mounting board (hereinafter, referred to as
A plurality of shield covers 8 are provided on the electronic component 5 constituting the radio unit, the electronic component constituting the transmitting / receiving unit, and the electronic component 7 requiring cooling such as an amplifier circuit. These shield covers 8 provide electromagnetic shielding between each electronic component and each electronic component. Further, these shield covers 8 are attached to the substrate 5 by soldering, and a spring-type contact finger 9 attached to the shield cover 8 is brought into contact with the shield plate 3, and the shield cover 8 and the contact fingers 9 are used. Each electronic component provided on the substrate 5 is grounded to the shield plate 3.

The heat-generating electronic component 7 is in contact with the heat sink plate 2 via a spacer 10 or a screw 11 made of a heat conductive material, so that heat generated from the electronic component 7 is radiated from the heat sink plate 2. I have. In the figure, reference numeral 12 denotes an IC which is an electronic component for controlling, 13 denotes a front panel for attaching and fixing a wireless unit to a dedicated rack, 14 denotes an external interface connector, 15 denotes a backplane-side interface connector of the dedicated rack,
Reference numeral 16 denotes a support interposed between the substrate 5 and the heat sink plate 2, and reference numeral 17 denotes a support between the substrate 5 and the heat sink plate 2 via the support 16.
And a screw for attaching.

[0007]

However, in the above-mentioned conventional wireless unit, a certain degree of shielding can be expected even with the heat sink plate 2 having such a mounting structure. For the purpose of cooling, the shield between the other wireless units is mainly performed by the shield plate 3 on one side, so that the shield between the other wireless units cannot be sufficiently performed. Was. Further, in the conventional wireless unit, a plurality of shield covers 8 are attached to the substrate 5 to shield the electronic components, and furthermore, in order to secure the ground using the shield cover 8, the shield cover 8 is contacted. A finger 9 is provided. Therefore, there is a problem that the number of parts increases and the assemblability is poor.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to provide a base station radio unit which rationally solves the above problems in view of the above-mentioned conventional circumstances. Another object of the present invention is to provide a base station radio unit that realizes a shield structure for electromagnetic waves with a reasonable structure that has a small number of parts and is easy to assemble. Still another object of the present invention is to provide a base station wireless unit that realizes a ground structure of electronic components housed therein with a reasonable structure with a small number of components and easy assembly. Further, it is an object of the present invention to provide a base station wireless unit capable of obtaining a stable shielding effect by minimizing deformation of a shield case and a mounting board due to a temperature change.

[0009]

According to a first aspect of the present invention, in a wireless unit provided in a base station of a wireless communication system, a pair of shield plates for covering a substrate on which a plurality of electronic components are mounted from front and back sides. And shield ribs that abut against the substrate and separate between the electronic component and the electronic component are integrally provided on the respective shield plates, and the opposing portions of the respective shield plates are provided on the substrate side, respectively. A fastening flange portion formed by being depressed is provided, and the opposed fastening flange portions are fastened to each other by a shield plate fastening screw having a thread portion length substantially equal to the thickness of the overlapped fastening flange portion. With this configuration, the substrate is housed between the pair of shield plates in a state where the space between the electronic component and the electronic component is shielded by the shield rib. It is a wireless unit for earth stations. The number, size, shape, thickness (degree of thinness), formation position on each shield plate, and the like of the fastening flange portion are not limited.

[0010]

In the base station radio unit according to the present invention, when the board on which a plurality of electronic components are mounted is covered with a pair of shield plates from the front and back sides, the shield rib integrated with each shield plate is placed on the front or back surface of the board. To separate the electronic component from the electronic component. Then, both shield plates,
Fastening is performed by a shield plate fastening screw having a length of a screw portion substantially equal to the thickness of the overlapped fastening flange portion. Thus, the electronic components are shielded by the shield ribs, while the substrate is housed between the pair of shield plates, and the substrate is shielded from other wireless units. Therefore, by the simple operation of attaching the shield plates, the board on which the electronic components are mounted can be shielded while sandwiched between the two shield plates, and the surroundings are surrounded by the shield ribs and the front and back sides are surrounded by the shield plates. In this state, it is possible to shield between the electronic components on the substrate and the electronic equipment.

Moreover, as described above, when the electronic component is partitioned by the shield ribs,
Since the shield rib integrated with each shield plate abuts on the front or back surface of the substrate, the electronic components on the substrate can be grounded to the shield plate. Further, a specific fastening operation of the pair of shield plates is performed by fastening the fastening flange portions arranged near the substrate with relatively short shield plate fastening screws. Accordingly, even if the environmental temperature repeatedly changes under the environmental conditions of the wireless unit, the fastening portion is less likely to be loosened.

That is, the wireless unit itself repeatedly cycles between high and low temperatures due to, for example, the effects of heat-generating components mounted on the board. For this reason, both shield plates and substrates constituting the wireless unit are constantly expanding and contracting. As a result, if the shield plate fastening screw that fastens the two shield plates is a long screw, the fastening portion is easily loosened. On the other hand, in the case of the short screw for fastening the shield plate, the width of expansion and contraction due to expansion and cooling due to temperature change is smaller than that of the long screw. Therefore, the shield plates are hardly loosened by the short screws and remain tightly fastened. As a result, it is possible to obtain a shield structure that is not affected by environmental changes, such as a shield that maintains reliable electrical characteristics over time and a mechanical structure that has a simple structure and secures the secrecy of the unit.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A radio unit for a base station according to the present invention will be specifically described based on one embodiment shown in FIGS. Note that FIG. 1 shows the wireless unit as CC in FIG.
FIG. 2 shows the appearance of the wireless unit in a front view, FIG. 3 shows the appearance of the wireless unit in a bottom view, and FIG.
5 shows the appearance of the wireless unit in a plan view, FIG. 5 shows the appearance of the wireless unit in a right side view, FIG. 6 shows the appearance of the wireless unit in a left side view, and FIG. 8 shows the wireless unit in a section taken along the line AA in FIG. 2, FIG. 9 shows the wireless unit in a section taken along the line BB in FIG. 5, and FIG. 10 shows the wireless unit in the section shown in FIG. It is shown in a section taken along the line DD.

As shown in the figure, the wireless unit of this embodiment forms a case by attaching a heat sink shield plate 22 on which cooling fins 21 are formed and a shield plate 23 with screws 24, and various electronic components are provided inside the case. Is mounted on the mounting board 25 on which the device is mounted. That is, the heat sink shield plate 22 and the shield plate 23
It is made of a box-shaped material having an electromagnetic shielding property with one surface opened, and by attaching these shield plates 22 and 23 so that their open surfaces are aligned with each other, the substrate 25 housed inside can be separated from the front and back and its surroundings. It is electromagnetically shielded and electromagnetically shielded from other wireless units (not shown) provided in a dedicated rack.

In this embodiment, each shield plate 22,
23, which is formed by depressing the respective portions toward the mounting board 25 side at a total of seven opposing portions including the vicinity of the four corners, the vicinity of the intermediate portion of the front rear side, and the center of one side. Flange portions f1 and f2 are provided. Each fastening flange f
1, f2 is provided with a screw hole. Here, the heat sink shield plate 22 and the shield plate 23 are formed in a box shape to shield the mounting board 25 from the surroundings.
These shield plates 22 and 23 may be formed in a flat plate shape, and the mounting substrate 25 may be sandwiched and accommodated from the front and back sides, so that the electromagnetic shielding property for other wireless units can be obtained. However, the fastening flange portions f1, f2 are provided on both shield plates 22, 23.
Must be formed.

On the board 25, there are mounted electronic components constituting a radio section, and electronic components 27 which need to be cooled, such as an amplifier circuit, and the like. A plurality of shield ribs 28 and 29 are integrally formed on the heat sink shield plate 22 and the shield plate 23 in order to electromagnetically shield the shield plate.
These shield ribs 28 and 29 are annularly projected at positions corresponding to each other, and when the heat sink shield plate 22 and the shield plate 23 are attached by screwing, the shield ribs 28 and 29 are provided. The tip of 29 abuts on the substrate 25 from the front and back surfaces, surrounds the electronic components mounted on the substrate 25 with shield ribs 28 and 29, and faces the heat sink shield plate 22 and the shield plate 2 in the front and back directions.
The electronic component is accommodated in a small box-shaped space formed by these electromagnetic shielding materials. Here, a specific screwing structure of the heat sink shield plate 22 and the shield plate 23 will be described. First, both the fastening flange portions f1 and f2 are overlapped, and these screw holes are brought into communication with each other. Are fastened to each other by the shield plate fastening screw 24 having a short screw portion 24a having substantially the same thickness as the fastening flange portions f1 and f2.

As described above, a plurality of small box-shaped shield spaces are formed, and electronic components are accommodated in these spaces to electromagnetically shield the electronic components from each other. The electromagnetic shield between the wireless units and the electronic unit can be obtained by simply performing the simple operation of attaching the heat sink shield plate 22 and the shield plate 23 without performing the complicated operation of soldering the cover. Electromagnetic shielding between the component and the electronic component can be secured. And furthermore, shield rib 2
Since the substrates 8 and 29 are in contact with the substrate 25 from the front and back surfaces, the substrate 25 is firmly supported in the wireless unit without providing a support as in the related art. Moreover, since the heat sink shield plate 22 and the shield plate 23 constituting the case of the wireless unit are supported by each other via the shield ribs 28 and 29, the wireless unit itself is robust against external force.

Further, in this embodiment, the fastening structure of the pair of shield plates 22 and 23 includes the fastening flange portions f1 and f2 which are formed to be depressed toward the substrate 25, respectively. A structure for fastening with screws 24 is employed. For this reason, for example, as shown in an arrow cross section when the wireless unit according to another embodiment of the present invention shown in FIG. 11 is cut at the position CC in FIG. 9, the fastening flange portions f1 and f2 are formed by depression. (Shield ribs 28a, 2)
9a) Compared to the case where the two members are fastened with a long shield plate fastening screw 24A, loosening of the screws is less likely to occur, and the ground contact between the shield case composed of the shield plates 22 and 23 and the substrate 25. Stabilizes.

This is because environmental conditions such as the substrate 25
Due to the influence of the heat-generating components mounted on the wireless unit, the wireless unit itself repeatedly switches between high and low temperatures, and even if there is a dimensional change in the pair of shield plates 22, 23 and the substrate 25,
This is because the fastening flange portions f1 and f2 are brought closer to the substrate 25 side and the fastening portions are fastened by the shield plate fastening screws 24 having short screw portions. That is, if the electronic component 27 is short, the width of expansion and contraction of the screw portion accompanying expansion and cooling due to temperature change due to heat generation of the electronic component 27 is small. Therefore, even if the shield plates 22 and 23 greatly expand and contract due to heat change, both members 2
The screws 2 and 23 are not easily loosened by the short screw 24 having a small expansion and contraction width. As a result, both members 22, 23 remain firmly fastened. As a result, a shield structure that is simple and is not affected by environmental changes can be obtained, and good electrical characteristics can be obtained. In addition, the shield rib 28a for the long shield plate fastening screw 24A includes:
An internally threaded tap hole 28b is provided. On the other hand, the shield rib 29a has a deep boss hole 2
9b is drilled.

As described above, in the base station radio unit, if the screw is once tightened in the manufacturing process, the fastening force of the shield plate fastening screw 24 hardly affects the temperature change. In addition, the electrical characteristics can be measured in the next step. Further, since a sufficient effect of preventing loosening can be obtained only by a general spring washer,
There is no need for other measures to prevent loosening, such as application of Loctite (loosening inhibitor) to a.

At the tips of the shield ribs 28 and 29, conductive wire mesh gasket packings 30 and 31 are provided, respectively.
Each of the electronic components provided on the substrate 25 is reliably grounded to the shield plates 22 and 23 by contacting the electronic components 8 and 29 with the substrate 25 via the gasket packings 30 and 31. Further, as described above, the gasket packings 30, 31
Is provided, the board 25 is reliably electrically connected to the shield plates 22 and 23. Further, in the base station wireless unit installed outdoors, the gasket packing 30,
By means of 31, it is possible to prevent dust and rainwater from entering the small box-shaped shield space and protect the electronic components housed in the shield space. In the present invention, such gasket packings 30 and 31 do not always need to be provided, and the same level of shielding and grounding properties as those of the related art can be obtained.

The heat sink shield plate 22 includes
The heat conducting ribs 32 are formed integrally with the board 25 so that the electronic parts 27 constituting the amplifying circuit, which are the heat generating parts, are attached to the heat conducting ribs 32 together with the board 25 by the screws 33 having electrothermal properties. Have been. Therefore, the electronic component 27 of the amplifier circuit is in contact with the heat conductive rib 32 integrated with the heat sink shield plate 22, and the heat generated by the electronic component 27 of the amplifier circuit can be obtained without providing a heat conductive spacer as in the related art. Is directly transmitted from the heat conducting rib 32 to the heat sink shield plate 22, and heat is efficiently radiated through the heat sink shield plate 22. This allows
Thermal deterioration of the electronic component is prevented. In this embodiment,
One shield plate 2 of the pair of shield plates 22 and 23
2, the cooling fins 21 were formed as heat sinks.
The other one or both shield plates 22 and 23 may be used as a heat sink. In short, in any case, it is only necessary that the above-mentioned heat conducting ribs 32 be provided integrally with a shield plate serving as a heat sink.

Here, in the figure, 36 is an IC which is an electronic component for controlling, 37 is a front panel for mounting the wireless unit on a dedicated rack, 38 is an external interface connector, and 39 is an interface on the backplane side of the dedicated rack. The connector 41 is a spacer made of a heat conductive material, and these are the same as in the above-described conventional example. Further, in this embodiment, the board 25 is divided into two parts, these boards are connected by the interface connector 40, the IC 36 is mounted on one board 25, and the amplifier circuit electronic component 27 is mounted on the other board 25. Implemented. However, in the present invention, even when these components are mounted on one board, the same function and effect can be obtained.

[0024]

As described above, according to the present invention,
Since the board on which the electronic components are mounted is sandwiched and covered from the front and back sides of the board by a pair of shield plates integrated with the shield ribs, a large number of components can be obtained simply by attaching these shield plates with screws. Without any need, electromagnetic shielding between other wireless units and electromagnetic shielding between electronic components can be reliably performed, and the shielding ribs integrated with each shield plate abut on the front or back surface of the substrate, so that electronic components on the substrate can be removed. Can be grounded to the shield plate. Further, a base unit wireless unit having excellent mechanical strength can be realized by the shield rib.

When the pair of shield plates are fastened as described above, the board is sandwiched by the shield case from the front and back sides, and the fastening flange portions designed near the board are relatively short. Since it was made to tighten using the shield plate fastening screw,
It is possible to simplify the assembling process of the base station wireless unit and to stabilize the electrical characteristic accuracy and the like.

[Brief description of the drawings]

FIG. 1 is a diagram showing a wireless unit according to one embodiment of the present invention in a cross section taken along line CC in FIG.

FIG. 2 is a front view illustrating an appearance of a wireless unit according to an embodiment of the present invention.

FIG. 3 is a diagram showing the appearance of a wireless unit according to one embodiment of the present invention in a bottom view.

FIG. 4 is a plan view showing an appearance of a wireless unit according to an embodiment of the present invention.

FIG. 5 is a right side view showing the appearance of the wireless unit according to one embodiment of the present invention.

FIG. 6 is a diagram showing the appearance of the wireless unit according to one embodiment of the present invention as viewed from the left side.

FIG. 7 is a perspective view showing the appearance of the wireless unit according to one embodiment of the present invention as viewed from the back.

FIG. 8 is a diagram showing a wireless unit according to one embodiment of the present invention in a sectional view taken along the line AA in FIG. 2;

FIG. 9 is a diagram showing a wireless unit according to one embodiment of the present invention in a sectional view taken along the line BB in FIG. 5;

FIG. 10 shows a wireless unit according to one embodiment of the present invention in FIG.
It is shown in a cross section taken along the line DD in FIG.

11 is a cross-sectional view of a wireless unit according to another embodiment of the present invention when cut at a position CC in FIG. 9;

FIG. 12 is a plan view showing the appearance of a conventional wireless unit.

FIG. 13 shows a conventional wireless unit as A1-A1 in FIG.
It is a figure shown by the arrow cross section.

FIG. 14 is a diagram showing a cross section of a conventional wireless unit in a plan view.

FIG. 15 shows a conventional wireless unit as B1-B1 in FIG.
It is a figure shown by the arrow cross section.

FIG. 16 shows a conventional wireless unit replaced with C1-C1 in FIG.
It is a figure shown by the arrow cross section.

[Explanation of symbols]

 Reference Signs List 22 heat sink shield plate, 23 shield plate, 24 shield plate fastening screw, 24 a screw portion, 25 mounting board, 27 electronic components, 28, 29 shield rib, f1, f2 fastening flange portion.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5E321 AA02 AA03 AA11 CC22 GG01 GG05 GH03 GH07 5K067 AA42 BB04 BB22 EE10 EE32 KK17

Claims (1)

[Claims] 1. A wireless unit provided in a base station of a wireless communication system, comprising: a pair of shield plates for covering a board on which a plurality of electronic components are mounted from front and back directions, and contacting the board with the electronic components. Shield ribs for partitioning between the electronic components are provided integrally with each shield plate, and a facing flange portion of each shield plate is provided with a fastening flange portion formed by depressing the facing portion toward the substrate, By fastening the opposed fastening flange portions to each other with a shield plate fastening screw having a screw portion length substantially equal to the thickness of the overlapped fastening flange portions, the electronic component and the electronic component can be connected to each other. The base plate is accommodated between the pair of shield plates in a state where is shielded by the shield ribs.