JP4272211B2 - Ground plate and method of manufacturing the same - Google Patents

Description

  In the present invention, not only when an electronic device is newly installed, but also supplementary construction at the time of failure can be easily and economically performed, and the connection of the electronic device is effective in suppressing high frequency noise of about 20 MHz. The present invention relates to a ground plane and a high-frequency grounding device.

In recent years, the influence of high frequency noise on electronic devices or the generation of high frequency noise from electronic devices has become a problem. That is, an electronic device may be affected by its operation due to high-frequency noise generated in the vicinity thereof. In addition, the electronic device itself becomes a source of high-frequency noise, and it is easy to cause a situation that the operation of other electronic devices is disturbed. This is due to the fact that a wide variety of electronic devices have been used in large quantities. Of course, measures have been taken in advance so as not to generate an unnecessary electromagnetic field exceeding a predetermined value by setting a standard. However, there are many cases in which high-frequency noise is generated due to a very slight change in the operating state or aging of the member. Here, high-frequency noise means a high-frequency electromagnetic field that is useless for electronic equipment. It is noise, but of course it is not acoustic. In general, it refers to electromagnetic waves at a level that can cause electronic devices to malfunction.

  Generally, this type of failure in an electronic device is a so-called intermittent failure that does not always occur reliably. For this reason, it is difficult to individually take measures for the device. However, high frequency noise can cause electronic devices to malfunction, and some measures should be taken.

  As in the case of a device using general electricity, the electronic device is connected to the ground terminal 11 of the distribution board 10 serving as the power source, as shown in FIG. 11 to the ground via the ground line 13.

  In this case, the ground wire 13 generally uses a sufficiently thick wire as a wire, and therefore has a relatively low electrical resistance. For this reason, the impedance is low and effective for commercial AC and DC.

  In this case, since the ground wire 13 is pulled out from the ground terminal 11 of the distribution board 10 and grounded, the length of the ground wire becomes long. As a result, the inductance of the ground wire 13 increases. Along with this, the impedance of the ground wire 13 increases. A high-impedance ground line is not useful for the above-described suppression of high-frequency noise. For example, in the case shown in FIG. 2, the cross-sectional area of the ground line 13 is sufficiently large, and the resistance value may be regarded as almost 0Ω. However, although the inductance varies depending on the thickness and cross-sectional shape (for example, a flat braided wire), the inductance increases as the length of the ground wire 13 increases. For example, assuming that 0.5 to 1 μH per meter, if the frequency of the high frequency noise is 10 MHz, even if the inductance is 0.5 μH / m, the impedance is 1570Ω at 50 m. Such a ground line 13 does not function as a ground conductor in a high frequency range.

Therefore, in order to suppress high-frequency noise as described above in electronic devices, it has been proposed to use so-called high-frequency grounding together as shown in FIG. That is, regardless of the shape, a copper plate having an area of 0.3 m ² or more and a thickness of about 0.8 mm is conductively bonded to the floor surface 3 a of the concrete floor 3 on the steel frame 2 of the building and used as the ground plate 15. It is connected to this by a connecting wire 16 (one) having a length of 1.5 m or less and a cross-sectional area of 3.5 mm ² or more. Here, the connection line 16 is a line that is connected to the electronic device itself or the casing thereof, and is used to connect them to a high-frequency grounding plate for grounding. However, in this specification, in order to distinguish from the ground wire which is a thick conducting wire for directly connecting the ground electrode of the distribution board to the ground 1 , it is referred to as a connection line.

In the case of FIG. 2, the free access floor 14 is used, and the distribution board 10 is installed on the free access floor 14. Raised floor 14 has a structure in which the floor plate 14a is supported by the support legs 14b.

  Conventionally, as a countermeasure against high frequency noise when newly installing an electronic device such as a computer, as shown in FIG. 3, a large area is placed on the floor of the building itself directly below the floor plate 14a of the free access floor where the electronic device is installed. A copper plate is laid as the ground plate 15. When there are a plurality of ground plates 15, the ground plates 15 are connected by a braided wire 15a, and the ground plate 15 and a device housing (not shown) are connected at multiple points by a braided wire (not shown). There is an example in which a rubber plate is placed between the copper plate and the floor for insulation.

  The method as shown in FIG. 3 provides good results for suppressing high frequency noise. However, it takes time to connect the braided wires for the plurality of ground plates 15, and it is difficult to perform the construction except when newly installed.

  In order to solve the above-described various problems related to the ground plate, the present applicant has proposed a high-frequency grounding method for electronic equipment (JP-6-104066-A). In this method, a conductive grounding plate having an insulating surface on its surface including a peripheral edge surface is provided on a conductive structure of a building with a flooring material for an electronic device to be grounded at a high frequency. The ground plate and the electronic device are connected using a plurality of connection lines. Here, the plurality of connection lines are connected in a distributed manner at positions separated from each other on the conductive ground plate. When the electronic device is grounded by this method, a sufficiently low ground impedance can be obtained up to a high frequency of about 20 MHz. In addition, by standardizing materials and construction methods, it is expected that costs will be kept low and high-frequency noise countermeasures can be easily implemented.

  By the way, noise countermeasures such as grounding seem simple at first glance, but in practice, there are many cases where the plan on the desk alone does not work. This is because on-site construction may not be performed as planned. Therefore, in order to reliably realize the measures, it is necessary to clearly define the materials used for that purpose. JP-6-104066-A proposes an excellent grounding method for countermeasures against high frequency noise.

  However, JP-6-104066-A does not disclose what kind of ground plate should be specifically used. For example, there is no suggestion of a solution to the problem of where the protrusion terminal is provided on the ground plate is efficient in relation to the ground effect and the size of the ground plate. Further, the structure of the protruding terminal for connecting the ground plate and the cable is not specifically shown. Therefore, these points remain as problems to be solved in order to realize the grounding method proposed in the above JP-6-104066-A in the future.

An object of the present invention is to provide a ground plate for high-frequency grounding that can be easily constructed and can reliably suppress high-frequency noise, and a grounding device using the ground plate.
In order to achieve the above object, according to a first aspect of the present invention, there is provided a ground plate connected to an electronic device by a connection line for suppressing high frequency noise of the electronic device, the conductor plate, and the conductor At least one projecting terminal for connecting a connecting line connected to the electronic device, the projecting terminal being inclined at an angle θ with respect to the ground plate. A ground plate is provided that protrudes from the surface.

  The angle is preferably 45 degrees or more and less than 90 degrees, for example.

  A plurality of the protruding terminals may be provided on the ground plate, and the protruding directions may be the same.

  The conductor plate can be formed in a square shape, for example. Further, the protruding terminal has a seat part for bonding to the conductor plate, and a joint part provided integrally with the seat part and coupled to the connection line, and the seat part has the rectangular shape. It can be arranged in parallel with any one side of the conductor plate.

  Further, according to the second aspect of the present invention, the ground plate is connected to the electronic device by the connection line and suppresses high frequency noise of the electronic device, and is provided on the conductive plate, the conductive plate, A plurality of projecting terminals for connecting connection lines connected to the electronic device, and the projecting terminals are equal to each other in a maximum circle that does not overlap each other with the center position of each projecting terminal as a center. A ground plate is provided which is provided at a position that can be formed on the conductor plate by a radius.

  According to the third aspect of the present invention, there is provided a high-frequency grounding device for suppressing high-frequency noise of an electronic device, comprising: a conductive grounding plate; and the grounding plate and the electronic device connected to each other. Each of the plurality of connection lines includes a connection terminal for connection to the electronic device at one end, and is connected to the ground plate at the other end. The grounding plate has a conductor plate, and a plurality of protruding terminals provided on the conductor plate for connecting connection wires connected to the electronic device, A high frequency grounding device is provided in which the protruding terminal protrudes from the ground plate in an inclined state with respect to the ground plate at an angle θ.

  According to the fourth aspect of the present invention, there is provided a high-frequency grounding device for suppressing high-frequency noise of an electronic device, a conductive grounding plate, and a plurality of connections for connecting the grounding plate and the electronic device. The ground plate has a conductor plate, and a plurality of projecting terminals provided on the conductor plate for connecting connection wires connected to the electronic device, A high-frequency grounding device is provided in which maximum circles that do not overlap each other centered on the center position of each protruding terminal are provided at positions where they can be formed on the conductor plate with the same radius.

  Here, the circle is formed in a size corresponding to the area of the conductor plate capable of realizing an upper limit frequency that functions as a ground plate in a series resonance circuit formed by the conductor plate and a connection line connected thereto. be able to.

According to a fifth aspect of the present invention, there is provided a high-frequency grounding device for suppressing high-frequency noise of an electronic device, comprising: a conductive grounding plate; and a connection between the grounding plate and the electronic device. A plurality of connection lines, the ground plate includes a conductor plate, and a plurality of projecting terminals provided on the conductor plate for connecting connection lines connected to the electronic device. The number of protruding terminals provided on the plate is such that the impedance at the lower limit frequency at which high-frequency noise should be suppressed in the series resonance circuit formed by the conductor plate and the connection line connected to the conductor plate is a value that can function as a ground plate. The area of the conductor plate that becomes smaller is A _2, and the area A ₁ of the conductor plate that can realize the upper limit frequency that functions as a ground plate is an integer n that is closest to the quotient of (A ₂ / A ₁ ). Provided with high frequency grounding device That.

According to a sixth aspect of the present invention, there is provided a high-frequency grounding device for suppressing high-frequency noise of an electronic device, wherein a plurality of ground plates made of a conductor plate are connected to the ground plate and the electronic device. Each of the ground plates has an area A ₁ capable of realizing an upper limit frequency that functions as a ground plate in a series resonant circuit formed by the ground plate and the connection wires connected thereto. In the series resonance circuit formed by the grounding plate and the connecting wire connected to the grounding plate, the number of the connection lines and the grounding plate functions as a grounding plate with an impedance at a lower limit frequency at which high-frequency noise should be suppressed. Provided is a high-frequency grounding device characterized in that the area of the conductor plate smaller than a possible value is A ₂ and is an integer n closest to the quotient of (A ₂ / A ₁ ).

  According to a seventh aspect of the present invention, in the method of manufacturing a ground plate for suppressing high frequency noise of an electronic device, the metal plate is cut into a predetermined shape and size, and the seat portion of the L-shaped tab terminal is Adhering to a predetermined position on the metal plate in a predetermined orientation in an electrically conductive state, covering the joint portion of the L-shaped tab terminal to be connected to the cable with a mask, There is provided a method for manufacturing a ground plate, wherein an L-shaped tab terminal is coated with an insulating material and the mask is removed.

  The best mode for carrying out the present invention will be described below with reference to the drawings. In addition, this invention is not limited to the form described below.

  As shown in FIGS. 1 (a), (b) and (c), as a best mode, the present invention provides a high-frequency grounding device that constitutes a standard countermeasure set that standardizes high-frequency grounding materials and construction methods. suggest. According to this set, anyone can easily take measures anywhere.

  As shown in FIG. 1A, the high-frequency grounding device according to the present invention is connected to an electrically conductive grounding plate 110 in which other portions are insulated except for a connecting portion with a connection line, and an electronic device. In order to connect the connecting lines to be connected, a plurality of L-shaped tab terminals 100 which are protruding terminals soldered to the ground plate 110 are provided. Further, as shown in FIG. 1C, a plurality of connection cables 160 connected to the plurality of L-shaped tab terminals 100 are further provided.

  The connection cable 160 is a conductive wire having an insulating coating 130. Used as a connection line. Specifically, the insulating coating 130 is a conductive wire whose surface is coated with vinyl. A crimp terminal 140, which is a connection terminal for connection to an electronic device, is connected to one end of the connection cable 160, and a difference such as a Faston terminal connected to the L-shaped tab terminal 100 is connected to the other end. Plug-in connection terminal 150 is connected.

  As shown in FIG. 1B, the L-shaped tab terminal 100 includes a seat portion 102 that is bonded to a ground plate and electrically connected, and a coupling portion 104 to which a connection line is coupled. The coupling portion 104 and the seat portion 102 are both formed of a conductive material such as metal. Further, the coupling portion 104 and the seat portion 102 are integrally provided with an angle θ. This angle θ is set to an angle at which the coupling portion 104 protrudes from the surface of the ground plate 110 when the seat portion 102 is attached to the surface of the ground plate 110. Usually, the angle is perpendicular to the ground plate 110.

However, the magnitude of the angle θ is preferably set so that the angle formed with the ground plate 110 is not less than 45 degrees and less than 90 degrees as shown in FIGS. 1 (a) and 1 (b). The reason for such an angle is that, in a narrow space such as a free access floor, in order to mount the plug-in type connection terminal 150 of the connection cable 160 on the coupling portion 104, it is inclined from a state perpendicular to the ground plate. This is because it is easier to work. On the other hand, as the angle becomes smaller than 45 degrees, the connection cable 160 needs to be largely bent when the connection cable 160 is connected to the device, so that a problem that the inductance increases according to the bending is likely to occur. In view of the workability, the angle range is preferably 45 degrees to 60 degrees. In terms of workability, the closer to 45 degrees, the better.

  The arrangement of the plurality of L-shaped tab terminals 100 on the ground plate 110 is, for example, as shown in FIG. 1A, in the case of a square ground plate 110, three L-shaped tab terminals on one diagonal line. 100 can be arranged. A preferred position for arranging the L-shaped tab terminal 100 will be described later.

  When the L-shaped tab terminal 100 is arranged, it is preferable to arrange so that the inclinations of the coupling portions 104 are aligned in the same direction as shown in FIG. By doing in this way, when inserting the plug-in type connection terminal 150 of the plurality of connection cables 160 into each of the plurality of coupling portions 104, the operation of inserting each plug-in type connection terminal 150 in the same direction is repeated. , So each can be connected and efficient.

  By the way, it is preferable that the ground plate 110 has a square or rectangular shape in consideration of the manufacturing process, storage, and conveyance. On the other hand, when a large number of ground plates 110 are installed on the floor of the building where the ground plates 110 are installed, it is conceivable to arrange the sides of each ground plate 110 in parallel with the sides of the room. Therefore, it is more preferable to align the direction of the seat portion 102 so as to be parallel to any side of the grounding plate 110 as compared to an arrangement that does not. In this way, the direction and positioning of the seat portion 102 when the seat portion 102 is bonded to the ground plate 110 may be based on the side where the ground plate 110 is located. As a result, it becomes easy to mechanize the adhesion of the seat portion 102 to the ground plate 110. Further, in this way, when the plug-in connection terminals 150 of the plurality of connection cables 160 are inserted into the plurality of coupling portions 104, the plug-in connection terminals 150 are connected to the seats of the ground plate 110. It can be said that it is efficient because it can be connected by repeating the insertion operation by aligning in the direction parallel to the side where the portions 102 are arranged.

  Further, the coupling portion 104 may have a structure in which when the ground plate 110 is carried in, the portion is laid down so as to be parallel to the plane of the ground plate, and is caused when the connection line is connected. . At this time, it is preferable that the cause angle is 45 degrees or more and less than 90 degrees. In this way, by setting the coupling portion 104 in the laid state, the ground plates can be stacked at the time of carry-in, and there is an advantage that bulkiness is reduced when carrying a large number of ground plates.

  Further, the L-shaped tab terminal 100 is provided with a lock hole 106 as shown in FIG. On the other hand, a lock projection 151 is provided inside the plug-in connection terminal 150. When the L-shaped tab terminal 100 is inserted and fitted into the plug-in connection terminal 150, the locking projection 151 inside the plug-in connection terminal 150 is fitted into the lock hole of the L-shaped tab terminal 100. ing.

  The reason why the L-shaped tab terminal is adopted as in the present embodiment is that, as will be described later, when the ground plate is laid on the floor of the building itself, it is connected to the electronic device located above the ground plate 110. This is because the wiring can be performed with a short length and a small amount of bending.

  In general, it takes time to connect the connection line to the conductive plate, and a connection tool is required. In the embodiment of the present invention, the projecting terminal is bonded in advance to the conductive plate by soldering or the like as shown in FIG. For this reason, the operation | work at the time of construction becomes easy. Further, the tab terminal can be fitted without a special tool. Instead of soldering, the tab terminal may be screwed to the ground plate, joined by welding, or crimped.

  Instead of the L-shaped tab terminal 100, a T-shaped tab terminal 200 as shown in FIGS. 4A and 4B can be used. 4A and 4B, the T-shaped tab terminal 200 includes a seat portion 202 that is electrically connected to the ground plate 110 and a coupling portion 204 to which the connection line is coupled.

  The coupling portion 204 protrudes from the surface of the ground plate 110 and is electrically connected to the seat portion 202. Further, the T-shaped tab terminal 200 is provided with a lock hole 206 as shown in FIG. 4 (b), like the L-shaped tab terminal 100, and the plug-in connection terminal 150 shown in FIG. 1 (C). When the T-shaped tab terminal 200 is inserted and fitted, the locking projection 151 inside the plug-in connection terminal 150 is configured to fit into the lock hole 206 of the T-shaped tab terminal 200. In the case of the T-shaped tab terminal 200, since the seat portion 202 is larger than the L-shaped tab terminal, the contact area with the ground plate 110 is increased.

  The T-shaped tab terminal 200 is also preferably formed so that the coupling portion 204 forms an angle θ with respect to the seat portion 202, as in the L-shaped tab terminal described above. In this case, the magnitude of the angle θ, the direction in which the angle θ is projected, and the direction of the seat portion are aligned with any side of the ground plate 110 are the same as in the case of the L-shaped tab terminal described above.

  Furthermore, instead of the L-shaped tab terminal 100, a plurality of cut-and-raised terminals 300 as shown in FIGS. 5 (a) and 5 (b) may be provided. As shown in FIG. 5 (a), the cut-and-raised terminal 300 is partially cut in advance, and the cut-and-raised terminal 300 is raised and used at the time of construction as shown in FIG. 5 (b). To do. Further, like the L-shaped tab terminal 100, the cut-and-raised terminal 300 is provided with a lock hole 306 as shown in FIG. 5B, and is cut into the plug-in connection terminal 150 shown in FIG. When the raised terminal 300 is inserted and fitted, the lock protrusion inside the plug-in connection terminal 150 is configured to fit into the lock hole of the cut and raised terminal 300. In this case, the thickness of the ground plate is set so as to be fitted to the plug-in connection terminal 150. When the cut-and-raised terminal 300 is provided, it is not necessary to provide a connection terminal such as a tab terminal. Also, when carrying in, it can be laid parallel to the plane of the ground plane, and when connecting the connection line, it can be raised so that it is almost perpendicular to the plane of the ground plane. The ground plate can be stacked, making it easy to carry. Moreover, you may make it equip each cut-out type terminal with the connector for couple | bonding a connection line.

  In the case of the cut-and-raised terminal 300 shown in FIG. 5A and FIG. 5B, an example in which the cut-and-raised direction of the terminal 300 is aligned with the diagonal direction of the ground plate 110 is shown. However, also in the case of the cut-and-raised terminal 300, if the direction of the cut-and-raised line is aligned with any side of the ground plate 110 in the same manner as the arrangement direction of the seat portion 102 of the L-shaped tab terminal described above, the insertion is performed. The mold connection terminal 150 is preferably attached more easily. Also, the size of the terminal cut-and-raised angle θ with respect to the ground plate 110 and the alignment of the protruding direction are the same as in the case of the L-shaped tab terminal described above.

  The material of the ground plate 110 can be a conductive metal such as copper, aluminum, or iron. The present inventors examined various materials to determine which material is good and what thickness should be used. According to it, as a result of repeated impedance measurement experiments using a so-called impedance analyzer that has a good reputation in the range of 10 kHz to 100 MHz, it is any material of copper, aluminum, and iron. However, almost no difference was observed. Therefore, it can be said that any material having electrical conductivity is sufficient for the ground plate 110. Further, as a result of an impedance measurement experiment with the thickness of the ground plate 110 being changed to 0.2 mm, 0.5 mm, and 2.0 mm, it was found that almost no difference was recognized. Therefore, any thickness may be used. In consideration of carrying around and handling, it is desirable to be as thin as possible. The impedance analyzer is a measuring instrument that measures a potential difference generated between both measurement terminals by a current flowing through an impedance measurement target. In this measuring instrument, no current flows from the measuring terminal to the measuring instrument itself.

  Of course, the planar size of the ground plate 110 affects the capacitance and inductance. It also differs depending on the frequency band intended for noise suppression. Moreover, if the area is large, it is inconvenient to handle, or high-frequency noise interference occurs after the electronic device is installed, and it is difficult to perform construction when taking countermeasures. Therefore, in consideration of these points, the ground plate should have a preferable area. This point will be described later.

  A typical size set by the inventors through experiments is illustrated. That is, in the embodiment of the present invention, a 0.3 m × 0.3 m plate is cited as one of typical specifications in consideration of ease of handling.

In addition, the ground plate 110 is provided with an insulating process 120 on the back surface and the peripheral edge of the front surface. In order to insulate reliably, when it coat | covered with what is called an insulating film about 0.1 mm thick, a good experimental result was obtained. The insulation process 120 is performed to prevent the effect of the electrostatic capacity of the grounding plate, which will be described later, from being lost when the peripheral end surface of the grounding plate comes into contact with the iron support legs of the free access flooring and becomes in an electrically connected state. Because.

  Next, the size of the ground plate will be described. The inventors investigated the relationship between impedance and frequency for three types of ground plates of 0.3 m × 0.3 m, 0.3 m × 0.6 m, and 0.3 m × 1 m. As a result, a result as shown in FIG. 6 was obtained.

  In FIG. 6, the value in the case of 0.3 m × 0.3 m is a solid line, the value in the case of 0.6 m × 0.3 m is a broken line, and the value in the case of 1.0 m × 0.3 m is a one-dot chain line. Show. In FIG. 6, the minimum impedance value is slightly smaller as the area of the plate is larger. However, the frequency at which the minimum impedance value appears is lower as the area is larger, and the minimum value appears around 20 MHz on a 0.3 m × 0.3 m plate with a smaller area. This seems to be due to the influence of the inductance of the connection line. Further, distributed constant circuit characteristics appear from the vicinity where the minimum impedance value appears.

  Further, when the size of the ground plate is 0.3 m × 0.3 m, the length of the connection line from the high frequency grounding portion of the electronic device or its casing to the ground plate is 0.5 m or less. It is desirable. Fig. 7 shows the impedance measured when the grounding plate is 0.3m x 0.3m and connected with one connecting line of length 0.5m, 1.0m, 1.5m and 2.0m. The result was obtained. In the figure, the value at 0.5 m is a solid line, the value at 1.0 m is a broken line, the value at 1.5 m is a one-dot chain line, and the value at 2.0 m is a two-dot chain line. Each is shown. As shown in FIG. 7, it is understood that the length of the connection line must be 0.5 m or less in order to obtain a low impedance around 20 MHz.

  In the above discussion, the rough characteristics have been described on the premise of a structure in which one connection line is connected to one ground plate. However, in the present application, the present inventors further strictly examine the planar shape and area of the ground plate, and propose a more appropriate ground device. Therefore, the high-frequency characteristics of the ground plate are examined.

  Considering microscopically the situation where the current spreads from the connection point to the four directions on the grounding plate, the high-frequency grounding plate has a minute capacitance connected to the end of the path having a minute inductance, as shown in FIG. Think of it as an equivalent model in which things are repeatedly connected in series. According to this model, it takes time to propagate the current. Therefore, in the case of high frequency, even in the case of a relatively small ground plate having a size of 0.3 m × 0.3 m, it is connected to one point in the center of the plate. This alone does not effectively use the entire area of the board. That is, in FIG. 11, the grounding effect is large at the connection point P <b> 1, and the effect becomes smaller as it spreads toward the periphery, as shown by the concentration distribution of the grounding effect. Therefore, the region that effectively acts as the ground plate is limited to a certain range. This range Ea1 can be said to be a region where the ground plate effectively acts as an electrode of the capacitor.

  Next, a grounding device in which the ground plate and the connection line are connected will be examined. That is, for the grounding device, the appropriate size of the grounding plate and the conditions of how to connect to the connection line from the relationship between the resonance characteristics and the capacitance formed between the grounding plate and the ground Ask for.

First, the grounding device is represented by an equivalent circuit as shown in FIG. That is, as shown in FIG. 20, the equivalent circuit of the grounding device is configured by a circuit in which an inductance L and a capacitance C are connected in series, and is inserted and connected between the connection point P and the ground. Here, the time change of the impedance Z between the ground unit and the earth and (dZ / dt) and the series resonance frequency f _r becomes as follows.

This relationship is schematically shown in FIG. That is, as the frequency becomes higher, impedance Z is lowered, at a minimum in terms of the resonant frequency f _r, then, changes to increase. Here, there is an effect in the high frequency noise suppression is a frequency range lower than the resonance frequency f _r.

On the other hand, the ground plate 110 and the steel frame 2 of the building that can be regarded as the ground form a capacitor as shown in FIG. 21, for example. Here, _assuming that the area of the ground plate 110 is A, the relative permittivity of the concrete floor 3 is ε _s , and the thickness is d, the capacitance between the terminals a and b shown in FIG.

Assuming that the condition (ε _s , d) of the concrete floor 3 on which the ground plate 110 is laid is constant, the capacitance C is proportional to the size of the area A of the ground plate.

  Next, the following equation is obtained from the above equations (2) and (3).

  Here, the condition of the concrete floor and the inductance L of the connecting line are constant,

Then, equation (4) is

Or

It becomes.

Here, when the area of the ground plate is A ₁ and A ₂ (A ₁ <A ₂ ), the frequency characteristic of the impedance between the point P and the ground in FIG. 20 is as shown in FIG. As shown in FIG. 25, the ground plate has a lower resonance frequency when the area is larger than when it is smaller.

When the frequency condition (f _u = f _r ) at which the ground plate functions is obtained as a required condition, the area of the ground plate is determined by the above equation (6). If a ground plate having an area larger than the area of the ground plate determined by equation (6) is used, the upper limit of the frequency at which the ground plate functions is shifted to a lower frequency as shown in FIG. Therefore, the area determined by the equation (6) is defined as an effective electrode region as an electrode region having a limit area that can function as a ground plate at a target upper limit frequency.
Next, consider the lower limit of the frequency at which the ground plate functions. When the ground plate functions, the problem is the impedance Z. As shown in FIG. 25, when the area of the ground plate is reduced, the impedance is increased. Therefore, the impedance Z must be smaller than the predetermined value Z _{m at} the lower limit frequency f _{b at} which the ground plate functions. Z _m is

So

After all,

It becomes. The area A of the ground plate must be larger than the value of the above equation (8).

The formula (8) and the result of the formula (6) are contradictory. Therefore, assuming that the area obtained by equation (6) is A ₁ and the area obtained by equation (8) is A ₂ , an integer n closest to (A ₂ / A ₁ ) is considered, and a ground plate having an area of A ₁ is obtained. Consider connecting n in parallel. FIG. 22 shows an equivalent circuit thereof. FIG. 23 shows an equivalent circuit obtained by synthesizing the parallel circuit of FIG. The resonance frequency f _r in FIG. 23 is given by the following equation.

As described above, considering the upper limit frequency that can function and the lower limit frequency that can function at a desired impedance, in order to efficiently suppress high-frequency noise, a ground plane having an area A ₁ that satisfies the above equation (6) is used. It became clear that it was preferable to connect n sheets in parallel.

  FIG. 16 shows an example of a ground plate having a size corresponding to the effective electrode region. That is, the ground plate shown in FIG. 16 is an example in which one tab terminal is arranged and the ground plate 110 is a square circumscribing the effective electrode region. In the case of this example, the number of ground plates having a required capacitance is connected to one electronic device with the connection line for each ground plate. That is, a plurality of sets of ground plates and connection lines are connected in parallel.

  Note that the outer shape of the ground plate may be a disk that matches the circumference of the effective electrode region.

  By the way, as shown in FIG. 16, it takes a lot of work to arrange a plurality of ground plates for one electronic device. Therefore, a plurality of connection lines are connected to a single ground plate to form a plurality of effective electrode regions, and this is equivalent to a plurality of sets of the ground plate and connection lines in FIG. 16 described above connected in parallel. A grounding device may be configured. For example, as shown in FIG. 9, it is conceivable to arrange five connection points P1-P5 (five connection lines).

  However, in this case, what is important is the position where the connection point is provided. If a connection point is not provided at an appropriate position, a sufficient high frequency noise suppression effect cannot be obtained. That is, it is not possible to configure a grounding device equivalent to the above-described grounding plate and connection line in FIG. JP-6-104066-A mentioned above does not say anything about the appropriate position where the connection point is to be provided. The present invention makes this point clear.

  That is, in the present invention, a plurality of connection points provided on the ground plate are provided at positions where the largest circles that do not overlap each other with the respective connection points as the centers can be formed on the ground plate with the same radius. Specifically, the plurality of protruding terminals are arranged so that the center position of each protruding terminal is the position of the connection point. Hereinafter, various examples of arrangement of the protruding terminals will be described.

  When using five connection points P1-P5 (five connection lines) as shown in FIG. 12, and using three connection points P1-P3 (three connection lines) as shown in FIG. The impedance was measured with respect to the case where a connection point (one connection line) was used at one point in the center of the plate, and the result shown in FIG. 10 was obtained. In FIG. 10, the value when there are five connection lines is indicated by a solid line, the value when there are three connection lines is indicated by a broken line, and the value when there is one connection line is indicated by a one-dot chain line. As a result of the experiment, in the case of five, the impedance is lower at 20 MHz or more.

  However, considering actual construction, it is quite troublesome to always connect the five connecting lines. Therefore, in this embodiment, three connections are used.

  If there are three, the impedance is the lowest at about 20 MHz, and it is considered safe. In addition, the amount of time required for connection is less than in the case of five.

  The arrangement position of the L-shaped tab terminal 100 is determined so as to satisfy the above-described conditions. Considering the situation where the current spreads from the connection point to the four directions on the ground plate in a microscopic manner, the high-frequency grounding plate has a small amount in front of the path having a small inductance as shown in FIG. It can be considered as an equivalent model in which capacitors are connected repeatedly in series. For this reason, since the inductance increases as the distance from the connection point on the high-frequency ground plate of the connection line increases, the effect of the capacitor is lost.

  This state is schematically shown in FIGS. 11, 12, 14, 15 and 16. FIG.

  In each figure, the magnitude | size of the effect as a capacitor | condenser is shown in concentric form centering on the connection position P of a connection line. In other words, the density is increased as the effect increases, and the density decreases as the effect decreases. As is clear from this expression, in the case of a high frequency, it can be understood that not all the points of the ground plate act as a capacitor from the connection position of the connection line even if the conductor is a ground plate.

  As described above, the present inventors have studied with this point in mind that the largest concentric circle described above corresponds to the limit of the size of the capacitor electrode that can resonate at the target upper limit frequency. I found it. Therefore, this size is used as a guideline for determining the effective size of the ground plate used at high frequency. This circle is the effective electrode region described above. Note that the shape of this region is not necessarily a circle, but it can be approximated by a circle considering that the current flows radially.

  FIG. 11 shows the effective electrode region Ea1 in the case of a single connection line in a concentric shape with the connection position P1 of the connection line as the center. In FIG. 11, it can be seen that the region effective as a capacitor is almost only the center of the ground plate. That is, in the case of FIG. 11, it can be seen that the high-frequency grounding plate is too large to achieve the target upper limit frequency.

On the other hand, when the number of connection lines is five and the connection position P of the connection lines is arranged as shown in FIG. 12, the configuration of the equivalent circuit shown in FIG. 22 is substantially realized. A high-frequency grounding plate can be used effectively. In this case, the effective electrode regions Ea1-Ea5 having the same radius r when the positions P1-P5 at which the L-shaped tab terminals 100 are arranged are assumed to be the center of the circle are overlapped on the plane of the ground plate 110. Place it in a position where it will not be. The radius r of the effective electrode regions Ea1 to Ea5 can be obtained from the area assuming that the effective electrode region defined as described above is a circle.

  When the five L-shaped tab terminals 100 are arranged, in the case of the square ground plate 110, one is arranged at a position P1 where two diagonal lines intersect, and on the diagonal line 2r away from the arranged position. It arrange | positions at four positions P2-P5, respectively. Thus, by arranging the positions where each of the L-shaped tab terminals 100 are arranged close to each other on the condition that the effective electrode regions do not overlap with each other, the ground plate 110 having a large area has a low impedance, It is possible to suppress high-frequency noise up to a higher frequency.

  Further, as shown in FIG. 14, the position where each of the L-shaped tab terminals 100 is arranged may be on one diagonal line of the square ground plate 110. Such an arrangement is also effective. However, since the area per tab terminal is increased due to the small number of tab terminals 100, the resonance frequency is lowered, and the upper limit frequency is slightly lower than when five tab terminals are provided.

Then, what is shown in FIG. 15 is mentioned as what further reduced the ground plate 110 as a substantially required area. In the example shown in FIG. 15, three tab terminals are arranged in a line on the ground plate 110 so that the effective electrode regions Ea1, Ea2, and Ea3 at the target frequency are close to each other so as not to overlap. It is. The outer edge of the ground plate 110 has a shape that circumscribes the row of effective electrode regions Ea1, Ea2, and Ea3. Thereby, the area per one tab terminal can be made substantially equal to the effective electrode region. Therefore, the ground plate 110 shown in FIG. 15 can ensure suppression performance up to a higher frequency than in the case of FIG. In addition, the area of the ground plate 110 itself can be reduced. That is, the ground plate can be configured efficiently.

  In addition, for example, as shown in FIG. 17, four protruding terminals can be provided on the square ground plate 110. Further, as shown in FIG. 18, a triangular ground plate 110 can be formed. Further, as shown in FIG. 19, a circular ground plate 110 may be used.

In actual construction, the high-frequency grounding device having the above-described configuration is installed on the floor 3 of the building itself directly below the free access floor 14 on which electronic devices are installed as shown in FIG. The installation is schematically shown in FIG. 13B, for example. Specifically, in the embodiment of the present invention, the electronic device is disposed on the conductive structure of the building together with its housing with respect to each of the high-frequency grounding portions with a flooring interposed therebetween. Next, each of the protruding terminals (for example, the L-shaped tab terminal 100) of the square conductive ground plate 110 having a side of 0.3 m, the surface of which is subjected to insulation processing including the peripheral end face, has a length of .0. One end of each of the three connection cables 160 (plug-in connection terminal 150) having a connection wire of a conductive wire having a cross-sectional area of 1 mm ² or more and 5 m or less is connected. Furthermore, one end of the other end (crimp terminal 140) of each connection cable 160 is connected to the electronic device. As a result, the electronic devices are connected in a distributed manner at positions where their connection lines are separated from each other on the ground plate 110.

  This is compared with the example shown in FIG. If the example shown in FIG. 3 is shown typically, it will become as shown in FIG. As described above, the method of the conventional example shown in FIG. 3 does not specifically consider how to select the area of the ground plane in order to reliably suppress high frequency noise up to the target upper limit frequency. . Simply connecting the connection line to the ground plate. For this reason, although the area of the ground plate per connection line to be connected becomes large and the impedance is low, the resonance frequency becomes low and it is difficult to suppress noise up to the high frequency region. On the other hand, in the present invention, the shape of the ground plate and the arrangement of the connection position with the connection line are determined so that the resonance frequency can be increased and a low impedance can be realized. Therefore, there is a clear difference in terms of high-frequency noise suppression performance.

In addition, the ground plate shown in FIG. 13 (a) is very large, so it is inconvenient to handle, and even if it can be constructed at the time of newly installing the equipment, it is difficult to construct and the construction cost is high. On the other hand, as shown in FIG. 13 (b), a large number of high-frequency connections as shown in FIG. 13 (a) can be obtained by distributing the ground plates and rationally connecting the connection lines for grounding to the ground plate. Since the main plate is not used, handling is easy. Therefore, it can be easily constructed not only when the equipment is newly installed but also afterwards.

  In addition, if the equipment and casing to be grounded are not so large, the multipoint grounding is not necessarily required. As shown in FIG. 13 (b), it is almost the same even if connected to one part on the device or the housing side, and this is distributedly connected at positions separated from each other on the ground plate 110 using a plurality of connection lines. An effect is obtained.

  In this way, the ground plate that can realize the effective electrode area on the floor of the building itself is laid with a plurality of ground plates, and each ground plate is connected to the electronic device, thereby allowing high-frequency noise up to the target upper limit frequency. Can be reliably suppressed.

  As described above, the ground plate used in the present invention is the result of repeated experiments with the aim of implementing high-frequency grounding with standard materials and construction methods, and the best results in terms of cost effectiveness are obtained. Some forms described above are set as forms. Here, the size of the high-frequency ground plate may be a size corresponding to the effective electrode region. In addition, when providing a plurality of connection line connection terminals on one ground plate, the effective electrode regions defined for each connection terminal can be arranged without overlapping each other, and as a whole, the area is as much as possible. It is preferably formed so as to be small. In addition to this, it is preferable to adopt an optimum form in consideration of standardization and material economy. For example, the form shown in FIG. 15 is recommended. As a result of impedance measurement, the material and thickness of the ground plate hardly affect the ground effect.

  It is desirable that the length of the connecting line is not so long. For example, it is important to suppress to the above-described length. However, the influence of the connecting wire material and cross-sectional area is small.

If the cross-sectional area is too thin, it may break during handling. Therefore, it is assumed that a copper wire of 1 mm ² or more is used.

  Further, when the peripheral edge surface portion of the ground plate touches the support leg of the free access floor plate, the ground connection plate is brought into an electrically connected state, and the electrostatic capacitance effect of the ground plate does not appear. For this reason, the present invention insulates this end face portion so that such an occurrence does not occur.

  Next, a method for manufacturing the ground plate 110 will be described. In order to manufacture the ground plate, various methods are possible. A preferable example is as follows.

  First, the copper plate has a target size, for example, 0.3 m × 0.3 m. This is obtained by cutting a copper plate to this size.

Second, the seat portion 102 of the L-shaped tab terminal 100 is bonded to a predetermined position in a predetermined direction. Adhesion is a method that can ensure electrical conductivity and that the entire bottom surface of the seat portion 102 can be in electrical contact with the ground plate 110 as much as possible. Here, soldering is performed.

  Thirdly, a portion to be connected to the connection cable 160, that is, the coupling portion 104 is covered with a mask. Then, an insulating material is applied to the entire ground plate 110. As the insulating material, for example, an epoxy / polyester resin powder coating is used. In addition, it may replace with application | coating and the method of sticking an insulating film may be used.

Fourth, the mask is removed. Thereby, the ground plate 110 can be manufactured.
When this ground plate is used, the coupling portion 104 is caused to have an angle range of 45 degrees or more and less than 90 degrees as described above.

  According to the above-described embodiment of the present invention, when high frequency noise countermeasure construction was performed, the effect was recognized in about 80% of the countermeasure construction. High-frequency noise is an intermittent failure, and it is actually difficult to take countermeasures. The fact that 80% of the results were obtained is almost satisfactory.

  As described above, according to the present invention, a relatively small and easy to handle, for example, 0.3 m square ground plate is used, and the length of the line connecting the ground plate and the electronic device or the housing is reduced. Short, for example, less than 0.5 m, and when the number of connection lines is plural, for example, three, and the points connected to the ground plate are dispersed at plural points, the frequency is sufficiently low to reach a high frequency of about 20 MHz. A ground impedance is obtained. Moreover, by standardizing materials and construction methods as described above, costs can be kept low and high-frequency noise countermeasures can be easily taken. More specifically, the area of the ground plate is reduced, the length of each connection line is shortened, and the capacitive impedance between the ground plate including the connection line and the conductive structure of the building is 20 MHz. It can be suppressed to 20Ω or less.

  Further, according to the present invention, the connection position of the connection line with respect to the ground plate, that is, the position where the projecting terminal such as the tab terminal is provided is positioned close to the effective electrode area in consideration of the distribution of the high-frequency current. ing. As a result, it is possible to secure a capacitance necessary for suppressing high-frequency noise while reducing the size of the ground plate. In this specification, for convenience of explanation, a circle is assumed as an ideal shape of the effective electrode region. However, the effective electrode region means a region having a spread from the connection position, and is strictly geometric. It does not need to be a circle of shape.

  Furthermore, according to the embodiment of the present invention, since a plurality of connection terminals are provided in advance, it is easy to connect the connection lines. In addition, if a plug-in type connection terminal is pre-installed at the end of the connection line, simply inserting the connection terminal into the connection type connection terminal of the connection line and fitting them together makes the work at construction easier. It becomes.

  In addition, the grounding plate can be laid as it is without using a rubber plate or the like as in the prior art by insulating the back surface of the grounding plate and the peripheral edge of the surface. Becomes easy.

  As described above, according to the high-frequency grounding device of the present invention, it can be constructed very easily.

(A) is an external view of the high-frequency grounding device in the embodiment of the present invention, (b) is an external view showing an example of an L-shaped tab terminal that can be used in the high-frequency grounding device of the present invention, and (c) is the present invention. It is an external view which shows an example of the connection cable which can be used for this high frequency grounding apparatus. It is a figure which shows the state which has earthed | grounded the electronic device with the grounding wire and the high frequency grounding board in the distribution board. It is a figure explaining the method in which the favorable high frequency noise countermeasure effect was acquired in the conventional grounding method. (A) is an external view in the case of using the T-shaped tab terminal of the high frequency grounding apparatus in embodiment of this invention, (b) is an external view of the T-shaped tab terminal in embodiment of this invention. (A) Appearance view when using cut-and-raised terminal of high-frequency grounding device in embodiment of the present invention, (b) Appearance when raising and lowering-type terminal of high-frequency grounding device in an embodiment of the present invention is raised FIG. It is a figure which shows the relationship of the frequency of a grounding impedance at the time of changing the magnitude | size of a high frequency grounding board. It is a graph which shows the relationship between the grounding impedance at the time of changing the length of the connection line (however, one piece) of a high frequency grounding board. It is explanatory drawing of the equivalent model of a high frequency ground plane. It is explanatory drawing which shows the connection position at the time of connecting the ground plate in embodiment of this invention with five connection wires. It is a graph which shows the relationship between a ground impedance and a frequency at the time of connecting a grounding board with the connection line of 1, 0.5 m in length, respectively. It is explanatory drawing which shows typically the effect | action of a micro capacitor | condenser in the case of one connection line in this invention. It is explanatory drawing which shows typically the effect | action of a micro capacitor | condenser in case the connection line in this invention is five. (A) The figure which illustrates the conventional grounding method typically, (b) is a figure which illustrates typically the grounding method in embodiment of this invention. It is explanatory drawing which shows typically the effect | action of a micro capacitor | condenser in case this invention has three connection lines. It is explanatory drawing which shows the other example of the form of the ground plate in case the connection wire in this invention is three. It is explanatory drawing which shows the example of the ground plate of the magnitude | size equivalent to the effective electrode area | region in this invention. It is explanatory drawing which shows the example of the form of the ground plate in case the connection wire in this invention in this invention is four. It is explanatory drawing which shows the example in which the number of the connection lines in this invention is 3, and the shape of a ground plane is a triangle. It is explanatory drawing which shows the example in case the connection wire in this invention is five and the shape of a grounding board is circular. It is a circuit diagram which shows the equivalent circuit of a high frequency ground plane. It is explanatory drawing which shows typically the electrostatic capacitance formed between a ground plate and the earth. It is a circuit diagram which shows the equivalent circuit of the preferable connection state of a ground plate. It is a circuit diagram showing the said connection state with the series circuit. It is explanatory drawing which shows typically the frequency characteristic of the impedance in the equivalent circuit of a high frequency ground plane. It is explanatory drawing which shows typically the frequency characteristic of the impedance of the electrostatic capacitance which a high frequency ground plate forms with an area as a parameter.

Claims (6)

A ground plate installed on a concrete floor and connected to an electronic device by a connection line to suppress high frequency noise of the electronic device,
A conductor plate;
A plurality of protruding terminals provided on the conductor plate for connecting connection lines connected to the electronic device;
The number of protruding terminals provided on the conductor plate is such that the impedance Z at the lower limit frequency f _b at which high frequency noise should be suppressed in a series resonance circuit formed by the conductor plate and a connection line connected thereto is a ground plate. The area of the conductor plate that is smaller than the functionable value Z _m is A _2, and the area of the conductor plate that can realize the upper limit frequency that functions as a ground plate is A ₁ , which is the most quotient of (A ₂ / A ₁ ). A close integer n,
The resonant frequency f _r of the series resonant circuit, the capacitance of the capacitor formed with the ground plate and the ground, C, the relative dielectric constant of the concrete floor ε _s , the dielectric constant of vacuum ε ₀ , the thickness of the concrete floor Where d is the inductance of the connecting line and L is
The A ₁ is set as κ = Lε ₀ ε _s / d.
A ₁ = 1 / {κ (2πf _r ) ² }
And
A ₂ is set as κ ′ = ε ₀ ε _s / d.
A ₂ = 1 / {2πf _b κ′Z _m }
And
Wherein each projection terminals, contact the circle of the area A ₁ that does not overlap with each other around the center position of each projection terminals, and which are located in a position that can be formed on the conductor plate on the radius equal to each other Ground plate. The ground plate according to claim 1,
The conductor plate is square,
A plurality of the protruding terminals are arranged on a diagonal line of the conductor plate. The ground plate according to claim 1,
The conductor plate is rectangular,
A plurality of the projecting terminals are arranged along the long side of the conductor plate. The ground plate according to claim 1,
The ground plate is characterized in that the conductor plate is a disk. The ground plate according to claim 1,
Each of the protruding terminals protrudes from the ground plate in an inclined state with respect to the ground plate at an angle θ. In the manufacturing method of the ground plate to be installed on the concrete floor and suppress high frequency noise of electronic equipment,
A metal plate is cut into a predetermined shape and size to form a conductor plate ,
Adhering the seats of the L-shaped tab terminals to a plurality of predetermined positions on the conductor plate in a predetermined orientation and electrically conducting,
Cover the joint of each L-shaped tab terminal to be connected to the cable with a mask,
Coating the conductor plate and each L-shaped tab terminal with an insulating material;
Manufactured by removing the mask,
The number of the L-shaped tab terminals, in the series resonant circuit formed by the connection line and connected thereto and the conductor plate, the impedance Z at the frequency f _b of the lower limit to be suppressed high frequency noise can function as a ground plate An area _{n of the} conductor plate that is smaller than the value Z _m is A _2, and an area of the conductor plate that can realize an upper limit frequency that functions as a ground plate is A _{1. An} integer n closest to the quotient of (A ₂ / A ₁ ) And
The resonant frequency f _r of the series resonant circuit, the capacitance of the capacitor formed with the ground plate and the ground, C, the relative dielectric constant of the concrete floor ε _s , the dielectric constant of vacuum ε ₀ , the thickness of the concrete floor Where d is the inductance of the connecting line and L is
The A ₁ is set as κ = Lε ₀ ε _s / d.
A ₁ = 1 / {κ (2πf _r ) ² }
And
A ₂ is set as κ ′ = ε ₀ ε _s / d.
A ₂ = 1 / {2πf _b κ′Z _m }
And
Wherein a defined position on the said conductor plate to bond the seat of the L-shaped tab terminal, the circle of the area A ₁ that does not overlap with each other around the center position of each L-shaped tab terminals, each other equal radius A method for producing a ground plate, wherein the ground plate can be formed on the conductor plate.

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