Noise reduction structure

Abstract

To provide a noise reduction structure that contributes to reducing the effects of noise by disposing a noise-shielding metal plate with a shape that provides high noise-shielding effect between a noise source and a receiving antenna.SOLUTION: A noise reduction structure includes a noise-shielding metal plate shaped to form a region where a current generated by a noise source is reduced, and the noise-shielding metal plate is installed between a receiving antenna of the wireless device and a noise source such that the receiving antenna corresponds to a position within a region where the current generated by the noise source is reduced.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a noise reduction structure. [Background technology]

[0002] The following documents are available regarding shielding substrates:

[0003] Patent Document 1 relates to a shield substrate for a connector that has a high electromagnetic shielding effect. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 10-126086 Summary of the Invention [Problem to be solved by the invention]

[0005] The following analysis is given by the inventor.

[0006] In wireless devices, noise generated by the device itself or by surrounding devices can reduce reception sensitivity. This reduction in reception sensitivity due to noise is an issue that must be addressed. If the noise is generated by the device itself, a common and highly effective noise countermeasure is to shield the noise source, such as by covering the IC or other noise source with a metal wall. On the other hand, if the noise is generated by surrounding devices, it is often not possible to counter the noise source itself, and there are few effective countermeasures. Another factor that makes countermeasures difficult is that wireless devices are equipped with antennas, and covering the antennas impairs their original communication performance. Currently, there are no clear guidelines regarding shielding methods.

[0007] In situations where the noise source cannot be shielded, for example, when the noise source and receiver are separate devices, a metal plate is placed between the noise source and the receiving antenna to block the noise. In such cases, the metal plate needs to be large enough to provide a shielding effect, but the size of the metal plate that provides a shielding effect is determined by the frequency, and generally, a metal plate that is half the wavelength or larger will provide a reflection effect. Therefore, the lower the noise frequency, the longer the wavelength, so the larger the metal plate needs to be. However, in small devices, it is not possible to implement a metal plate of sufficient size, resulting in a problem of reduced shielding effect.

[0008] The present invention aims to provide a noise reduction structure that contributes to reducing the effects of noise by placing a noise-shielding metal plate (hereinafter also referred to as "metal plate") with a shape that provides high noise-shielding effect between a noise source and a receiving antenna. [Means for solving the problem]

[0009] According to a first aspect of the present invention, the noise-shielding metal plate has a shape that forms a region in which a current generated by a noise source is reduced, A noise reduction structure can be provided in which the noise-shielding metal plate is installed between the receiving antenna of a wireless device and the noise source so that the receiving antenna corresponds to a position within a region where the current generated by the noise source is reduced. [Effects of the Invention]

[0010] According to the present invention, it is possible to provide a noise reduction structure that contributes to reducing the influence of noise by placing a metal plate having a shape that provides a high noise shielding effect between a noise source and a receiving antenna. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a block diagram showing an example of the configuration of a noise reduction structure according to the present disclosure. [Figure 2] FIG. 1 is a block diagram showing the configuration of a dipole antenna. [Figure 3]FIG. 2 is a diagram illustrating an example of a noise source and a receiving antenna. [Figure 4] FIG. 10 is a diagram showing an example of a configuration in which a metal plate is placed between a noise source and a receiving antenna. [Figure 5] 10A and 10B are diagrams showing examples of a configuration in which a metal plate is placed between a noise source and a receiving antenna, as viewed from the receiving antenna side, and examples of transmission characteristics in each case. [Figure 6] 1A and 1B are diagrams showing an example of a metal plate of a noise reduction structure according to the prior art; [Figure 7] 1 is a diagram showing an example (trapezoid) of a metal plate of a noise reduction structure according to the present disclosure. [Figure 8] 1 is a diagram showing an example of a metal plate of a noise reduction structure according to the present disclosure (including an extension portion extending from the long side of a trapezoid). FIG. [Figure 9] 10A and 10B are diagrams illustrating an example of the noise reduction effect of an example metal plate (including an extension portion extending the long side of a trapezoid) having a noise reduction structure according to the present disclosure. [Figure 10] 1 is a diagram showing an example of a metal plate of a noise reduction structure according to the present disclosure (including an extension portion extending from the long side of a trapezoid). FIG. [Figure 11] 1 is a diagram showing an example of a metal plate of a noise reduction structure according to the present disclosure (including a notch in an extension portion of a trapezoidal long side); FIG. [Figure 12] 10A and 10B are diagrams illustrating an example of the noise reduction effect of an example metal plate (including a notch in an extension portion of a trapezoidal long side) having a noise reduction structure according to the present disclosure. [Figure 13] FIG. 1 is a diagram showing an example of a list of metal plates of a noise reduction structure according to the present disclosure. [Figure 14] 10A and 10B are diagrams illustrating an example of the noise reduction effect of an example metal plate (including an extended portion extending a quadrangle) having a noise reduction structure according to the present disclosure. [Figure 15] 10A and 10B are diagrams illustrating an example of the noise reduction effect of an example metal plate (including a notch in an extended portion of an extended quadrangle) having a noise reduction structure according to the present disclosure. [Figure 16] FIG. 7 is a diagram showing an example of current distribution on a metal plate of the noise reduction structure of the prior art shown in FIG. 6. [Figure 17] 8 is a diagram showing an example of a current distribution on a metal plate (trapezoid) of the noise reduction structure according to the present disclosure shown in FIG. 7. FIG. [Figure 18] 8 is a diagram showing an example of a current flowing on the metal plate (trapezoid) of the noise reduction structure according to the present disclosure shown in FIG. 7. FIG. [Figure 19] 9 is a diagram showing an example of a current distribution on a metal plate (extending along the long side of the trapezoid) of the noise reduction structure according to the present disclosure shown in FIG. 8. FIG. [Figure 20] 11 is a diagram showing an example of a current distribution on a metal plate (extending along the long side of the trapezoid) of the noise reduction structure according to the present disclosure shown in FIG. 10. FIG. [Figure 21] 12 is a diagram showing an example of a current distribution on a metal plate (extending along the long side of the trapezoid) of the noise reduction structure according to the present disclosure shown in FIG. 11. FIG. [Figure 22] 1A and 1B are diagrams showing an example (circular) of a metal plate of a noise reduction structure according to the present disclosure and an example of the noise reduction effect thereof. [Figure 23] 1A and 1B are diagrams showing examples of metal plates (circular and notched) with a noise reduction structure according to the present disclosure and an example of the noise reduction effect thereof. [Figure 24] 23 is a diagram showing an example of current distribution on a metal plate (circular) of the noise reduction structure according to the present disclosure shown in FIG. 22. FIG. [Figure 25] 24 is a diagram showing an example of current distribution on the metal plate (circle and notch) of the noise reduction structure according to the present disclosure shown in FIG. 23. FIG. [Figure 26] 1A and 1B are diagrams illustrating an example (doughnut-shaped) of a metal plate having a noise reduction structure according to the present disclosure and an example of the noise reduction effect thereof. [Figure 27] 27A and 27B are diagrams illustrating the reasons why the noise reduction effect cannot be obtained in the example (doughnut shape) of the metal plate having the noise reduction structure shown in FIG. 26. [Figure 28] 1A and 1B are diagrams illustrating an example of a metal plate (doughnut shape and notch (lower position)) with a noise reduction structure according to the present disclosure and an example of the noise reduction effect thereof. [Figure 29] 29 is a diagram showing the reason why the noise reduction effect cannot be obtained in the example of the metal plate with the noise reduction structure shown in FIG. 28 (donut shape and notch (lower position)). FIG. [Figure 30] 1A and 1B are diagrams illustrating an example of a metal plate (doughnut shape and notches (left and right positions of the hole)) having a noise reduction structure according to the present disclosure, and an example of the noise reduction effect thereof. [Figure 31] 1A and 1B are diagrams showing an example of a metal plate with a noise reduction structure according to the present disclosure (a doughnut shape and a cutout (left and right positions of the hole) with varying distances from the hole) and an example of the noise reduction effect thereof. [Figure 32] 27 is a diagram showing an example of a current distribution on the example donut-shaped metal plate shown in FIG. 26. FIG. [Figure 33] 31 is a diagram showing an example of current distribution on an example of a donut-shaped metal plate shown in FIG. 30 that includes cutouts (left and right positions of a hole). FIG. [Figure 34] 31 is a diagram showing an example of the noise reduction effect when the shape of the doughnut-shaped hole and the shape of the cutout (left and right positions of the hole) are changed in the metal plate of the example of the noise reduction structure according to the present disclosure shown in FIG. 30. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0012] In this disclosure, the drawings may relate to one or more embodiments. In addition, each embodiment described below can be combined with other embodiments as appropriate, and the present invention is not limited to each embodiment.

[0013] First, an overview of one embodiment will be described with reference to the drawings. Note that the reference numerals in the drawings attached to this overview are attached to each element for convenience as an example to facilitate understanding, and are not intended to limit the present invention to the illustrated form. Furthermore, connection lines between blocks in the drawings and the like referred to in the following description include both bidirectional and unidirectional lines. Unidirectional arrows are used to schematically indicate the flow of the main signal (data) and do not exclude bidirectionality.

[0014] FIG. 1 is a block diagram showing an example of the configuration of a noise reduction structure according to the present disclosure.

[0015] Referring to FIG. 1, a noise-shielding metal plate 100, a noise source 200, a wireless device 300, and a receiving antenna 400 are shown.

[0016] In the noise reduction structure 10, the noise-shielding metal plate 100 has a shape that forms an area where the current generated by the noise source 200 is reduced. The shape of the noise-shielding metal plate 100 forms an area where the current generated by the noise source 200 is reduced, thereby improving the noise-shielding effect.

[0017] The noise reduction structure 10 has a noise-shielding metal plate 100 installed between the receiving antenna 400 and the noise source 200 of the wireless device 300 so that the receiving antenna 400 corresponds to a position within the area where the current generated by the noise source 200 is reduced.

[0018] The noise-shielding metal plate 100 may be installed inside the wireless device 300. When the noise-shielding metal plate 100 is installed inside the wireless device 300, noise can be reduced, and a wireless device with good reception performance can be provided.

[0019] Therefore, according to one embodiment, a noise reduction structure can be provided that contributes to reducing the effects of noise by installing a metal plate with a shape that has a high noise shielding effect between the noise source and the receiving antenna.

[0020] [First embodiment] Next, a first embodiment will be described in detail with reference to the drawings. Note that the first to fourth embodiments described below are embodiments relating to the shape of the noise-shielding metal plate (also referred to as "metal plate") 100 installed between the noise source 200 and the receiving antenna 400 of the noise reducing structure 10 described in the above embodiment. Therefore, the metal plate described in each embodiment is installed between the noise source 200 and the receiving antenna 400 of the noise reducing structure 10 described in the above embodiment to constitute the noise reducing structure 10.

[0021] In the first embodiment, the noise source 200 and the receiving antenna 400 shown in Fig. 1 are each represented by a dipole antenna. The following description uses 850 MHz, which is used in the 4G-LTE (Fourth Generation-Long Term Evolution) communication system, as an example of a frequency. Therefore, a typical dipole antenna has a size of λ / 2 = approximately 180 mm (λ indicates the wavelength).

[0022] Fig. 2 is a block diagram showing the configuration of a dipole antenna. Fig. 2(a) shows an 850 MHz dipole antenna 500 including a signal input 550. In the first to fourth embodiments described below, a dipole antenna having a miniaturized shape using inductors 410 and 420 as the receiving antenna 400 shown in Fig. 2(b) will be used.

[0023] Fig. 3 is a diagram showing an example of a noise source 200 and a receiving antenna 400. Fig. 4 is a diagram showing an example of a configuration in which a metal plate 101 is disposed between the noise source 200 and the receiving antenna 400.

[0024] 3, when the noise source 200 and the receiving antenna 400 are arranged parallel to each other, the amount of noise received by the receiving antenna 400 is greatest. In this situation, assume that a metal plate 101 is placed between the noise source 200 and the receiving antenna 400, as shown in FIG. 4. The distances between the noise source 200 and the metal plate 101, and between the receiving antenna 400 and the metal plate 101, are each set to 40 mm, but these distances are not particularly important in the present invention.

[0025] Fig. 5 shows an example of a configuration in which a metal plate is placed between a noise source and a receiving antenna, as viewed from the receiving antenna side, and an example of the transmission characteristics for each case. That is, Fig. 5 is a diagram of Fig. 4 viewed from the receiving antenna 400 side, in which the noise source 200 and the receiving antenna 400, which is assumed to be a miniaturized dipole antenna, are placed horizontally and at the center of the metal plate 101, and the transmission characteristics (hereinafter referred to as S21) are shown correspondingly when the size of the metal plate 101 is changed.

[0026] S21 corresponds to the amount of radio waves radiated from the noise source 200 received by the receiving antenna 400, and is therefore an indicator of the influence of noise. S21 has a maximum value of 0 (zero) and is expressed as a negative number. The larger the number (closer to 0), the greater the influence of noise, and the smaller the number, the less the influence of noise. In the present disclosure, S21 is a number calculated using an electromagnetic field simulator.

[0027] In the simulation using the electromagnetic field simulator, the material of the metal plate 101 was iron, but there is no significant difference even if other metals such as copper, aluminum, or stainless steel are used. Therefore, the metal plate 101 may be manufactured using any material, or may be a combination of multiple metals. Note that in this embodiment and the other embodiments described below, the metal plate may be manufactured using any of the above materials.

[0028] 5 shows that S21 does not change significantly even when the distance between the noise source 200 and the dipole antenna representing the receiving antenna 400 and the side parallel to the receiving antenna 400, i.e., the width of the metal plate 101 in the up-down direction (i.e., vertical: 240 mm, 180 mm, 120 mm), is changed, but S21 changes significantly when the side perpendicular to the receiving antenna 400, i.e., the width of the metal plate 101 in the left-right direction (i.e., horizontal: 240 mm, 180 mm, 120 mm), is changed. Furthermore, it is well known that when the width in the left-right direction mentioned above is shorter than half the wavelength (λ / 2) of the desired frequency, radio waves can easily pass through, and when it is longer than half the wavelength, radio waves cannot easily pass through.

[0029] Fig. 6 is a diagram showing an example of a metal plate with a noise reduction structure according to the prior art. As an example of the prior art, a metal plate 101 shown in Fig. 6 having a width of 140 mm, which is shorter than half the wavelength, was used for comparison. In the first embodiment, the frequency was set to 850 MHz, so the half wavelength was approximately 180 mm.

[0030] Fig. 7 is a diagram showing an example (trapezoid) of a metal plate having a noise reduction structure according to the present disclosure. Referring to Fig. 7, which shows a first shape of a metal plate according to the present disclosure, in contrast to the example of metal plate 101 having a noise reduction structure according to the prior art shown in Fig. 6, the width at the position overlapping with receiving antenna 400, i.e., 40 mm from the top of metal plate 102 in the first shape (half the height of 80 mm), is 140 mm, the same as the width of metal plate 101 shown in Fig. 6, and the trapezoid has left and right sides tilted by 45°. S21 is -17 dB for the shape in Fig. 6, while it is -25 dB for the shape in Fig. 7, an improvement of 8 dB.

[0031] FIG. 8 is a diagram showing an example of a metal plate with a noise reduction structure according to the present disclosure (including extensions of the trapezoidal long sides). Referring to FIG. 8, the long sides of the two parallel sides of the trapezoidal metal plate 102 in FIG. 7 are extended in a direction away from the receiving antenna 400. FIG. 8 shows an example in which the metal plate 103 is extended by 40 mm, and the shape of this metal plate 103 represents a second shape of the metal plate according to the present disclosure. With the shape of the metal plate 103 shown in FIG. 8, S21 is further improved to -29 dB.

[0032] FIG. 9 is a diagram illustrating an example of the noise reduction effect of an example metal plate (including an extension portion extending the long side of a trapezoid) having a noise reduction structure according to the present disclosure. When the metal plate includes the extension portion extending the long side of the trapezoid, as shown in FIG. 9, the noise reduction effect is high when the length h2 of the extension portion is approximately 20 to 40 mm, but decreases to -21 dB when the length h2 is approximately 140 mm (the vertical width h1 of the trapezoid portion = 80 mm). When the length h2 of the extension portion is 20 to 40 mm, the noise reduction effect is high, expressed in terms of wavelength λ, which corresponds to 0.06 λ or more and 0.11 λ or less (f = 850 MHz). When h2 is 140 mm, the noise reduction effect decreases, corresponding to 0.4 λ (f = 850 MHz). This tendency remains unchanged even when the vertical width of the trapezoid portion, indicated by h1 in FIG. 9, is changed.

[0033] Fig. 10 is a diagram showing an example of a metal plate (including an extended portion of the long side of a trapezoid) having a noise reduction structure according to the present disclosure. The metal plate 104 shown in Fig. 10 is the shape in Fig. 9 that has the lowest noise reduction effect (however, h1 = 80 mm).

[0034] FIG. 11 is a diagram showing an example of a metal plate having a noise reduction structure according to the present disclosure (including a notch in the extended portion of the long side of the trapezoid). When the noise reduction effect is reduced, as in the case of metal plate 104 shown in FIG. 10, S21 can be improved by forming a predetermined notch in the extended portion of the long side of the trapezoid, as in the shape of metal plate 110 shown in FIG. 11. With the dimensions of metal plate 110 shown in FIG. 11, S21 improved to -32 dB. In FIG. 11, the notch in the extended portion of the long side of the trapezoid is positioned 40 mm below the bottom of the trapezoid in the vertical direction. This is so that the shape above the notch is the same as the shape of metal plate 103 shown in FIG. 8. Even when the dimension corresponding to h2 is set to 20 mm, as in the case of metal plate 103 shown in FIG. 9, a noise reduction effect can be expected.

[0035] FIG. 12 is a diagram showing an example of the noise reduction effect of an example metal plate (including a notch in the extension portion extending from the long side of the trapezoid) having a noise reduction structure according to the present disclosure. This diagram summarizes the change in S21 when the dimensions of the notch portion included in the extension portion of the metal plate 110 shown in FIG. 11 are changed. It shows that the noise reduction effect is high when the dimension W2 between the left and right notches is 100 mm or less. Expressed in terms of wavelength λ, this is approximately 0.3λ or less (f=850 MHz). Changing the vertical dimension W1 of the notch portion results in little change in S21. The shape of the metal plate 110 is the third shape of the metal plate according to the present disclosure.

[0036] Fig. 13 is a diagram showing an example of a list of metal plates for noise reduction structures according to the present disclosure. Referring to Fig. 13, the shapes are summarized in the list. Shapes (2), (3), and (5) correspond to the first, second, and third shapes according to the present disclosure, and it can be seen that they have a high effect of reducing noise S21.

[0037] On the other hand, Fig. 14 shows the characteristics when the metal plate is extended in a shape corresponding to (7) and (8) in Fig. 13. Fig. 14 is a diagram showing an example of the noise reduction effect of an example of a metal plate (including an extended portion of a rectangle) of a noise reduction structure according to the present disclosure. When metal plate 120 has a rectangular shape, extending the portion corresponding to h2 does not result in a significant change in the characteristics regarding the noise reduction effect.

[0038] Similarly, Fig. 15 shows a shape corresponding to (9) in Fig. 13 with different cutout dimensions. Fig. 15 is a diagram showing an example of the noise reduction effect of an example metal plate with a noise reduction structure according to the present disclosure (including a cutout in an extended portion of a rectangle). In metal plate 130 with an extended rectangular shape, changing the cutout dimensions does not result in a significant change in the characteristics regarding the noise reduction effect.

[0039] Next, the operation of the first embodiment will be described with reference to FIGS.

[0040] FIG. 16 is a diagram showing an example of current distribution on the metal plate 101 of the noise reduction structure of the prior art shown in FIG. 6. FIG. 16 shows the current distribution when the metal plate 101 is viewed from the front (receiving antenna 400 side). Noise radiated from a noise source 200 (not shown) placed at the back of the metal plate 101 becomes a noise current on the back of the metal plate 101, wraps around the left and right edges of the metal plate 101, and is transmitted to the front. Because the dipole antenna used as the noise source 200 is placed horizontally on the back, the noise current also flows horizontally, i.e., in the left-right direction. The magnetic field and electric field generated by this noise current radiate horizontally, so it can be said that the horizontally placed receiving antenna 400 is most susceptible to noise.

[0041] On the other hand, Fig. 17 is a diagram showing an example of current distribution on the metal plate (trapezoid) of the noise reduction structure according to the present disclosure shown in Fig. 7. That is, Fig. 17 shows an example of current distribution on metal plate 102, which is one shape of the metal plate of the noise reduction structure of the present invention, viewed from the front (receiving antenna 400 side). In Fig. 17, an area 102A where no current flows is generated above metal plate 102 relative to receiving antenna 400. This is the reason for the improvement in S21.

[0042] Next, the reason why the area 102A where no current flows occurs will be described with reference to FIG.

[0043] Fig. 18 is a diagram showing an example of a current flowing on the metal plate 102 (trapezoid) of the noise reduction structure according to the present disclosure shown in Fig. 7. In Fig. 18, the current flowing on the metal plate 102 is shown by arrows. Fig. 18(a) shows a perspective view of the rear side of the metal plate 102 (i.e., a view from the front, showing the current flowing on the rear side), and Fig. 18(b) shows the front side of the metal plate 102. The shading of the arrow indicates the strength of the current, with the darker the arrow, the stronger the current.

[0044] When noise radiated from the noise source 200 generates a horizontal current as shown in FIG. 18(a), the current is bent back at the left and right edges inclined at 45° and propagates toward the front side of the metal plate 102 as shown in FIG. 18(b). Because the left and right edges are inclined at 45°, the current propagating toward the front side changes direction to vertical as shown in FIG. 18(b). Furthermore, this current is stronger toward the noise source 200 (not shown) (near the center of the rear side of the metal plate 102). Therefore, as shown in FIG. 18(b), the vertical current on the front side of the metal plate 102 is stronger toward the upper part of the metal plate 102 and weaker toward the lower part. Therefore, at the upper part of the metal plate 102, the currents on the left and right sides have different directions and cancel each other out, resulting in an area 102A (shaded area) where no current flows between the currents. On the other hand, at the lower part of the metal plate 102, the current is weak and therefore the canceling effect is small.

[0045] Fig. 19 is a diagram showing an example of current distribution on a metal plate (extending the long side of the trapezoid) of the noise reduction structure according to the present disclosure shown in Fig. 8. In Fig. 17 described above, the area where no current flows was slightly shifted upward relative to receiving antenna 400, resulting in a small noise reduction effect for S21. In contrast, in the shape of metal plate 103 in which the bottom of the trapezoid is extended by 40 mm as shown in Fig. 8, receiving antenna 400 and area 103A where no current flows coincide with each other, as shown in Fig. 19, resulting in an increased noise reduction effect for S21.

[0046] Fig. 20 is a diagram showing an example of current distribution on a metal plate (extending the long side of the trapezoid) of the noise reduction structure according to the present disclosure shown in Fig. 10. In the shape of metal plate 104 in which the bottom of the trapezoid is further extended to 140 mm as shown in Fig. 10, area 104A in which no current flows moves too far downward as shown in Fig. 20, increasing the current near receiving antenna 400. This causes a deterioration in S21.

[0047] Fig. 21 is a diagram showing an example of the current distribution on a metal plate (extending the long side of the trapezoid) of the noise reduction structure according to the present disclosure shown in Fig. 11. In the case where S21 deteriorates as in the case of metal plate 104 shown in Fig. 20, if a notch is made in the 140 mm extension at the bottom of the trapezoid as in the shape of metal plate 110 shown in Fig. 11, the current distribution near receiving antenna 400 becomes equivalent to the current distribution in the case of metal plate 103 shown in Fig. 19, as shown in Fig. 21. As a result, the current in area 110A near receiving antenna 400 where no current flows is reduced, thereby improving S21.

[0048] According to the first embodiment, a noise reduction structure can be provided that contributes to reducing the influence of noise by placing a metal plate with a shape that provides a high noise shielding effect between the noise source and the receiving antenna.

[0049] [Second embodiment] Next, a second embodiment will be described in detail with reference to the drawings.

[0050] FIG. 22 is a diagram showing an example (circular) metal plate of a noise reduction structure according to the present disclosure and an example of its noise reduction effect. Referring to FIG. 22, the noise source 200 and the receiving antenna 400 are disposed 40 mm below the upper end of the metal plate 150 shown in FIG. 22(a), similar to the conditions in the first embodiment described above. When S21 is calculated assuming the diameter of the metal plate 150 is R, the characteristics shown in the graph in FIG. 22(b) are obtained. It can be seen from this graph that S21 tends to deteriorate when the diameter is between 220 mm and 280 mm. Note that FIG. 22(c) is a table showing the values ​​shown in the graph in FIG. 22(b).

[0051] FIG. 23 illustrates an example of a metal plate (circular and notched) with a noise reduction structure according to the present disclosure and its noise reduction effect. (a) of FIG. 23 illustrates a metal plate 160 with the upper end of the notch positioned 80 mm below the receiving antenna 400, as in the first embodiment. (b) of FIG. 23 illustrates a graph for each value of W1, with W1, W2, and R (the notch's vertical width, the distance between the notches, and the diameter, respectively) as parameters. (c) of FIG. 23 is a table illustrating the values ​​shown in the graph of (b) of FIG. 23. From these results, it can be seen that the degradation of S21 at diameters of 220 to 280 mm, which exists for the metal plate 150 of FIG. 22, is improved by adding notches, regardless of the values ​​of W1 and W2. This shape of the metal plate 160 is the fourth shape of the metal plate according to the present disclosure. The distance between the notches is preferably 0.3 wavelengths (λ) or less.

[0052] Next, the reason why adding a cutout improves noise reduction will be explained with reference to the current distribution. Fig. 24 is a diagram showing an example of the current distribution on the metal plate (circular) 150 of the noise reduction structure according to the present disclosure shown in Fig. 22. The diameter of the metal plate 150 was set to 260 mm, which is the degradation point. Referring to Fig. 24, it can be seen that a strong current flows near the receiving antenna 400.

[0053] Fig. 25 is a diagram showing an example of current distribution on metal plate (circle and notch) 160 of the noise reduction structure according to the present disclosure shown in Fig. 23. That is, Fig. 25 is a diagram showing current distribution on metal plate 160 in which notches have been added to metal plate 150. The diameter R is set to 260 mm, W1 = 60 mm, and W2 = 100 mm. It can be seen that an area 160A where no current flows is generated near receiving antenna 400.

[0054] As described above, according to the second embodiment, a noise reduction structure can be provided that contributes to reducing the effects of noise by placing a metal plate with a shape that has a high noise shielding effect between the noise source and the receiving antenna.

[0055] [Third embodiment] Next, a third embodiment will be described in detail with reference to the drawings.

[0056] FIG. 26 is a diagram showing an example (doughnut-shaped) metal plate having a noise reduction structure according to the present disclosure and an example of its noise reduction effect. FIG. 27 is a diagram showing the reasons why the example (doughnut-shaped) metal plate having a noise reduction structure shown in FIG. 26 does not achieve a noise reduction effect. (a) of FIG. 26 shows a donut-shaped metal plate 170 with a hole in the center. (b) of FIG. 26 shows S21 for a shape without a hole (i.e., the metal plate (circular) 150 shown in FIG. 22), and (c) of FIG. 26 shows S21 versus hole diameter. (d) of FIG. 26 is a table showing the values ​​of the graph in (c) of FIG. 26. Referring to (b) and (c) of FIG. 26, it can be seen that S21 tends to deteriorate when the hole diameter is 100 mm or greater for a shape without a hole. The grayed-out areas in the table in Fig. 26(d) are areas that were not evaluated because the holes overlap with the noise source 200 and the receiving antenna 400, as shown in Fig. 27(a), and therefore no shielding effect can be obtained. The hole in the center was made to anticipate actual use, such as passing a power cord or a fixing structure through it.

[0057] FIG. 28 is a diagram showing an example of a metal plate (doughnut-shaped and notched (lower position)) with a noise reduction structure according to the present disclosure and an example of its noise reduction effect. FIG. 29 is a diagram showing the reason why the example of the metal plate (doughnut-shaped and notched (lower position)) with a noise reduction structure shown in FIG. 28 does not achieve a significant noise reduction effect. (a) of FIG. 28 shows a metal plate 180 with the notch adopted in the first embodiment added to the doughnut-shaped metal plate 170 shown in FIG. 26 . (b) of FIG. 28 is a diagram plotting the values ​​shown in the table in (c) of FIG. 28 . The table in (c) of FIG. 28 shows S21 when the diameter R is changed relative to the hole diameter, W1, and W2. The graph in (b) of FIG. 28 reveals that adding a notch to the doughnut-shaped metal plate 180 does not achieve a significant noise reduction effect. The shaded areas in the table of FIG. 28(c) are areas that were not evaluated because the holes and notches overlap, as shown in FIG. 29(a), and the shape of the metal plate 180 cannot be maintained.

[0058] FIG. 30 is a diagram showing an example of a metal plate (doughnut shape and notches (left and right positions of the hole)) with a noise reduction structure according to the present disclosure, and an example of its noise reduction effect. In the case of a doughnut-shaped metal plate 170 as shown in FIG. 26(a), the countermeasure is to align the center positions of the notches at the same height as the center of the hole so that the notches are on the left and right sides of the hole, as shown in FIG. 30(a). FIG. 30(b) is a diagram plotting the values ​​shown in the table in FIG. 30(c), which shows S21 when the diameter R is changed relative to the hole diameter and W1. By using a metal plate 190 with this shape, a significant noise reduction effect can be obtained, especially for diameters of 220 to 280 mm. This shape is the fifth shape of the metal plate according to the present disclosure.

[0059] FIG. 31 is a diagram showing an example of a metal plate with a noise reduction structure according to the present disclosure (where the distance between the hole and the notch (left and right positions of the hole) is changed depending on the donut shape) and an example of its noise reduction effect. As shown in FIG. 31(a), the distance between the hole and the notch is set to D so that the notch is on the left and right sides of the hole. FIG. 31(b) is a diagram plotting the values ​​shown in the table of FIG. 31(c), and the table of FIG. 31(c) shows S21 when the diameter R is changed relative to the distance D between the hole and the notch. As shown in FIG. 31(b), it can be seen that with this shape, the closer the distance D between the hole and the notch, the greater the noise reduction effect.

[0060] Next, the reason why the noise improvement effect is enhanced will be described with reference to the current distributions shown in Fig. 32 and Fig. 33. Fig. 32 is a diagram showing an example of the current distribution on the donut-shaped metal plate 170 shown in Fig. 26. Fig. 33 is a diagram showing an example of the current distribution on the donut-shaped metal plate 190 shown in Fig. 30, which includes cutouts (left and right positions of the hole). It can be seen that, compared to the current distribution in the area 170A where no current flows near the receiving antenna 400 on the donut-shaped metal plate 170 shown in Fig. 32, the current is reduced in the area 190A where no current flows near the receiving antenna 400 on the metal plate 190 with cutouts added on the left and right sides in Fig. 33.

[0061] According to the third embodiment, a noise reduction structure can be provided that contributes to reducing the influence of noise by placing a metal plate with a shape that provides a high noise shielding effect between the noise source and the receiving antenna.

[0062] [Fourth embodiment] Next, a fourth embodiment will be described in detail with reference to the drawings.

[0063] Fig. 34 is a diagram showing an example of the noise reduction effect when the shape of the doughnut-shaped hole and the shapes of the cutouts (left and right positions of the hole) are changed in metal plate 190, which is an example of the noise reduction structure according to the present disclosure shown in Fig. 30. In the third embodiment, the S21 value is shown when the shape of the doughnut-shaped hole is circular and the left and right cutouts are rectangular. In contrast, Fig. 34 shows S21 when the hole shape is circular, diamond-shaped, or rectangular, and the left and right cutout shapes are circular, diamond-shaped, or rectangular. The shape shown in the fourth embodiment, in which the hole is circular and the left and right cutouts are rectangular, provides the greatest noise reduction effect in S21.

[0064] According to the fourth embodiment, it is possible to provide a noise reduction structure that contributes to reducing the influence of noise by placing a metal plate having a shape that has a high noise shielding effect between the noise source and the receiving antenna.

[0065] The noise-shielding metal plates (metal plates) 100, 101, 102, 103, 104, 110, 120, 130, 150, 160, 170, 180, and 190 described in the embodiment and the first to fourth embodiments and the noise-shielding metal plates (metal plates) shown in Fig. 34 may be installed inside the wireless device 300 shown in Fig. 1. When the noise-shielding metal plates 100, 101, 102, 103, 104, 110, 120, 130, 150, 160, 170, 180, and 190 and the noise-shielding metal plates (metal plates) shown in Fig. 34 are installed inside the wireless device 300, it is possible to reduce noise and provide a wireless device 300 with good reception performance.

[0066] The reason is that with this invention, even in cases where the noise-shielding metal plate in a small wireless device is less than 1 / 2 wavelength (λ) and sufficient shielding effect cannot be obtained, the noise reduction effect can be increased by changing the shape of the noise-shielding metal plate.

[0067] Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and further modifications, substitutions, and adjustments can be made without departing from the basic technical concept of the present invention. For example, the network configurations, element configurations, and message expression formats shown in the drawings are examples to aid in understanding the present invention, and the present invention is not limited to the configurations shown in these drawings. Furthermore, "A and / or B" is used to mean at least either A or B.

[0068] Finally, preferred embodiments of the present invention will be summarized. [First form] The noise-shielding metal plate of the noise-reducing structure may have a shape that forms an area where the current generated by the noise source is reduced. In the noise reduction structure, the noise-shielding metal plate may be installed between the receiving antenna of the wireless device and the noise source so that the receiving antenna corresponds to a position within a region where the current generated by the noise source is reduced. [Second form] In the noise reduction structure according to the first aspect, it is preferable that the shape includes two sides that are inclined at 45° with respect to two parallel sides of the trapezoid. [Third Form] In the noise reduction structure according to the first aspect, the shape includes two sides that are inclined at 45° with respect to the two parallel sides of the trapezoid, and The trapezoid includes an extension portion extending from a long side of the two parallel sides in an extension direction perpendicular to a short side of the two parallel sides of the trapezoid, The extended length of the extension portion is preferably 0.06 wavelength (λ) or more and 0.11 wavelength (λ) or less of the wavelength (λ) of the signal of the noise source to be shielded. [Fourth Form] In the noise reduction structure according to the first aspect, the shape includes two sides that are inclined at 45° with respect to the two parallel sides of the trapezoid, and The trapezoid includes an extension portion extending from a long side of the two parallel sides in an extension direction perpendicular to a short side of the two parallel sides of the trapezoid, It is preferable that the extension portion has notches on both of two sides parallel to the extension direction. [Fifth Form] In the noise reduction structure according to a fourth aspect, the extended length of the extension portion is 0.4 wavelengths (λ) of the wavelength (λ) of a signal of the noise source to be shielded, the notch is provided with its origin at a position that is 0.06 wavelengths (λ) or more and 0.11 wavelengths (λ) or less away from the long side of the trapezoid, It is preferable that the distance between the notches provided on both of the two sides parallel to the extension direction is 0.3 wavelengths (λ) or less. [Sixth Form] In the noise reduction structure according to the first aspect, the shape is preferably circular and includes notches provided on opposing edge edges that are symmetrical about the circle. [7th form] In the noise reduction structure described in the sixth aspect, the notch is provided on a line passing through the edge and center of the circle, the notch being spaced apart from the position of the noise source, which is located closer to the edge than the center, by a distance equal to the distance between the edge and the noise source toward the center of the circle, and further having a starting point at a position spaced apart from the position of the noise source by 0.06 wavelengths (λ) or more and 0.11 wavelengths (λ) or less in the same direction as the center, The distance between the notches is preferably 0.3 wavelengths (λ) or less. [8th form] In the noise reduction structure according to a first aspect, the shape is a doughnut shape, notches provided on a first outermost edge of the doughnut shape and on a second outermost edge and a third outermost edge of the doughnut shape that are point-symmetrically opposed to each other across the center of the doughnut shape on a line perpendicular to a line passing through the noise source and a center of the doughnut shape, Preferably, the donut-shaped hole is circular. [9th Form] In the noise reducing structure according to the first aspect, it is preferable that the noise-shielding metal plate is installed inside the wireless device. [10th Form] In the noise reducing structure according to the first aspect, it is preferable that the noise-shielding metal plate is made of iron, copper, aluminum, stainless steel, or a combination thereof.

[0069] The disclosures of the above-cited patent documents are incorporated herein by reference. Modifications and adjustments of the embodiments and examples are possible within the scope of the entire disclosure of the present invention (including the claims), and further based on the basic technical concept thereof. Furthermore, various combinations and selections of the various disclosed elements (including each element of each claim, each element of each embodiment or example, each element of each drawing, etc.) are possible within the scope of the disclosure of the present invention. In other words, the present invention naturally embraces various modifications and alterations that would be possible by a person skilled in the art in accordance with the entire disclosure and technical concept, including the claims. In particular, with regard to the numerical ranges set forth herein, any numerical value or subrange within the range should be construed as specifically set forth, even if not otherwise specified. Furthermore, the disclosures of the above-cited documents, when used in part or in whole in combination with the disclosures herein as part of the disclosure of the present invention, in accordance with the spirit of the present invention, are also deemed to be included in the disclosures of this application. [Explanation of symbols]

[0070] 10 Noise reduction structure 100, 101, 102, 103, 104, 110, 120, 130, 150, 160, 170, 180, 190 Noise shielding metal plate (metal plate) 102A, 103A, 104A, 110A, 160A, 170A, 180A Area where no current flows 200 Noise Source 300 Wireless equipment 400 receiving antenna

Claims

1. The noise-shielding metal plate has a shape including two sides that are inclined at 45° with respect to two parallel sides of the trapezoid, A noise reduction structure in which the noise-shielding metal plate is installed between the receiving antenna of a wireless device and a noise source arranged parallel to the receiving antenna, so that the receiving antenna extends parallel to two sides of the trapezoid and is positioned at half the height of the trapezoid.

2. the shape includes an extension portion extending from a long side of the two parallel sides of the trapezoid in an extension direction perpendicular to a short side of the two parallel sides of the trapezoid, 2. The noise reduction structure according to claim 1, wherein the extended length of the extension portion is equal to or greater than 0.06 wavelengths (λ) and equal to or less than 0.11 wavelengths (λ) of the wavelength (λ) of the signal of the noise source to be shielded.

3. the shape includes an extension portion extending from a long side of the two parallel sides of the trapezoid in an extension direction perpendicular to a short side of the two parallel sides of the trapezoid, The noise reduction structure according to claim 1 , wherein the extension portion has notches on both of two sides parallel to the extension direction.

4. The extended length of the extension portion is 0.4 wavelengths (λ) of the wavelength (λ) of the signal of the noise source to be shielded, the notch is provided with its starting point at a position that is 0.06 wavelengths (λ) or more and 0.11 wavelengths (λ) or less away from the long side of the trapezoid, The noise reduction structure according to claim 3 , wherein a distance between the notches provided on both of the two sides parallel to the extension direction is 0.3 wavelengths (λ) or less.

5. The noise reduction structure according to claim 1 , wherein the shape is circular and includes notches provided on opposing edges of the circle in line symmetry.

6. the notch is provided on a straight line passing through the edge and center of the circle, the notch being spaced from the position of the noise source, which is located closer to the edge than the center, toward the center of the circle by a distance equal to the distance between the edge and the noise source, and further having a starting point at a position spaced from the position of the noise source by 0.06 wavelengths (λ) or more and 0.11 wavelengths (λ) or less in the same direction as the center, The noise reduction structure according to claim 5 , wherein the dimension between the notches is 0.3 wavelengths (λ) or less.

7. The shape is a donut shape, notches provided on a first outermost edge of the doughnut shape and on a second outermost edge and a third outermost edge of the doughnut shape that are point-symmetrically opposed to each other across the center of the doughnut shape on a line perpendicular to a line passing through the noise source and a center of the doughnut shape, The noise reduction structure of claim 1 , wherein the donut-shaped hole is circular.

8. The noise reducing structure according to claim 1 , wherein the noise-shielding metal plate is installed inside the wireless device.

9. 2. The noise reducing structure according to claim 1, wherein the noise-shielding metal plate is made of iron, copper, aluminum, stainless steel, or a combination thereof.

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