JP2011087266A - Floor face/wall face two-dimensional communication system capable of wireless power-feeding - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a system wherein a dielectric substrate is selected as a two-dimensional (2D) communication transmission medium, wireless power feeding is made compatible with 2D communication, and 2D communication on a floor surface/wall surface or the like is performed with a directional sensor for exciting and detecting a TM surface wave on a surface of the dielectric substrate. <P>SOLUTION: Low-frequency power-feeding electrodes 5, 6, 7, 8, 9 are configured for a ground plate 11 via a dielectric layer. The electrodes are separated with a slit of 0.5 mm. A low frequency voltage is applied to the electrodes 5, 7, 9. Wireless power-feeding pickup electrodes 1, 2, 3, 4 are disposed via a dielectric substrate 10 which is extremely thin (about 300 μm). Power is fed from the low frequency power-feeding electrodes 5, 6, 7, 8, 9 through the extremely thin dielectric substrate 10 to these pickup electrodes by electrostatic coupling. The pickup electrodes can be supplied with power while moving in the direction of slits. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a technique related to excitation and detection of electromagnetic waves in an electromagnetic wave communication system using a two-dimensional plane such as a floor surface or a wall surface capable of wireless power feeding as a transmission medium.

  Many television terminals and PCs are overflowing in homes and offices, such as the multi-channel television accompanying the digitization of broadcast waves and multimedia supported by IT technology. It is desired to connect these information home appliances to some home network. Furthermore, if you can connect general home appliances that are conventionally unrelated to information home appliances, such as air conditioners, baths, and locking systems, to the same network, network-compatible TVs, not to mention network-compatible baths, Network-compatible air conditioners, network-compatible doors, etc. will be realized, and convenience in the home will be dramatically improved.

  However, in order to efficiently perform communication between these many devices, (1) conventional connection using a plurality of coaxial cables, (2) use of power line transportation, (3) low power wireless transmission Use, (4) Use infrared transmission, etc., but (1) has a problem of cable congestion, and (2) and (4) can satisfy all the requirements of the home network with a transmission band of 10 Mbps or less. It cannot be said that (3) has been studied in the 2.4 GHz, 5 GHz, 19 GHz, 25 GHz, and 60 GHz bands. Although introduction of wireless LAN technology using these radio waves into a home network is conceivable, the problem of communication between rooms which is different from the problem of radio wave leakage has not been solved.

  Recently, in order to respond to these problems, there has been proposed a communication system using a two-dimensional planar transmission line in which a floor surface is formed of a dielectric substrate. [Non-Patent Document 1] However, the problem of reflection of electromagnetic waves on the end face of the dielectric substrate and the problem of large transmission loss remain as problems, and a stable two-dimensional communication technique has not been established.

  In addition, it is necessary to anticipate the emergence of support-type intelligent walking robots in future homes and offices. In such a case, it is desired that the power supply to the robot is seamlessly performed directly from the floor surface or the like. That is, wireless power feeding is desired. It is necessary to develop a two-dimensional communication system using a two-dimensional plane that enables such wireless power feeding.

  Japanese Patent Application No. 2009-185210 “Floor / Wall 2D Communication System”; Yozo Utsumi (Application July 16, 2009).

  "Simultaneous signal and power transmission using surface microwaves"; Hiroto Itai, Zhangbei, Hiroyuki Shinoda, Shingaku Giho USN2007-21, PP. 115-118, May 2007

  In Non-Patent Document 1, which is a prior art document, a mesh-like conductive thin plate is installed on the dielectric surface of a conductive plate-backed dielectric substrate that achieves both DC power feeding and two-dimensional communication, and is in contact with the conductive thin plate. A non-directional transmission / reception sensor is arranged to perform two-dimensional communication. Therefore, an increase in transmission loss due to the conductor loss of the mesh-like conductor thin plate and deterioration of phase characteristics due to reflection at the end face of the substrate have become problems.

  In order to remove the conductor loss of the mesh-like conductor thin plate and simplify the structure, the mesh-like conductor thin plate itself is removed by a low frequency (about 1 MHz) power supply using electrostatic coupling and the like on the surface of the dielectric layer. A method of performing two-dimensional communication by arranging direct transmission / reception sensors is conceivable. However, in order to obtain an appropriate electrostatic coupling strength, the thickness of the dielectric layer is required to be extremely thin (about 300 μm). However, it becomes extremely difficult to trap the microwave surface wave on the dielectric surface of the ultrathin dielectric substrate backed by the conductive plate. Therefore, the development of a transmission / reception directivity sensor having good reflection characteristics by efficiently exciting and trapping microwave surface waves on the dielectric surface of the ultrathin dielectric substrate backed by the conductor plate is an issue to be solved.

Means 1 for solving the problem

In an example of a floor / wall structure with a wireless power feeding function as shown in FIG. 1, a mechanism that enables two-dimensional communication using a TM surface wave is developed.
11, 5, 6, 7, 8, 9 low-frequency feed electrodes are configured via a dielectric layer with respect to 11 ground plates. Each electrode is separated by a 0.5 mm slit. A low frequency voltage is applied to 5, 7, and 9. 1, 2, 3, and 4 wireless power pickup electrodes are arranged through 10 ultrathin (about 300 μm) dielectric thin plates. Power is supplied to these pickup electrodes from low frequency power supply electrodes 5, 6, 7, 8 and 9 through 10 ultrathin dielectric substrates by electrostatic coupling. The pickup electrode can receive power supply while moving in the slit direction.

  For example, the transmission directivity sensor shown in FIG. 3 is connected to one pickup electrode, and the reception directivity sensor is connected to four pickup electrodes, so that transmission / reception can be performed in a positional relationship as shown in FIG. . However, transmission between the two pickup electrodes 1 and 4 in FIG. 1 is transmission through two slots as shown in the figure.

  The biggest problem of this development is that the thickness of the uppermost conductive plate-backed dielectric substrate in the structure of FIG. 1 reduces the coupling (C coupling) due to the capacitance to enable wireless power feeding (about 1 MHz). ), It is necessary to make the film very thin and about 300 μm.

  As shown in FIG. 2, energy is trapped and propagated from the dielectric surface of the dielectric substrate (thickness t) to the evanescent wave that decays exponentially from the dielectric surface. A two-dimensional communication system using a floor surface, a wall surface, or the like that detects a TM surface wave (Transverse Magnetic Wave) trapped on the dielectric surface and transmitted on the dielectric surface using a transmission sensor. Develop. Here, by imparting directivity to the transmission / reception sensor, the S parameter S21 (transmission characteristics) is increased and the S11 (reflection characteristics) is decreased.

Since the transmitter / receiver sensor can excite and detect TM surface waves on the dielectric surface, communication is possible by sliding the substrate surface when moving the sensor, and the access point can be freely selected to form a flexible network. can do. In addition, since each sensor has directivity, the propagation direction of the radio wave can be narrowed to some extent, so that there is no need for an absorber having a large dielectric loss angle loaded on the end face of the substrate used as a multipath countermeasure.
Further, the radio wave excited by the transmission sensor efficiently reaches the reception sensor, and transmission loss can be reduced while maintaining good phase characteristics.

  The taper-shaped microstrip line type directivity sensor shown in FIG. 3 is installed oppositely on the surface of the conductive plate-backed dielectric substrate shown in FIG. FIG. 4 shows the positional relationship between the transmission sensor and the reception sensor. An electromagnetic field simulation was performed with the configuration shown in FIGS. In FIG. 3, the tapered conductor plate is placed on a dielectric having a thickness h. As shown in the figure, the characteristic impedances of the transmission line constituted by the microstrip line central conductor and conductor plate-lined dielectric substrate having the above-mentioned shapes are Z1 and Z2, respectively.

In FIG. 3, Z ₁ = 200Ω and Z1 = 100Ω are selected as a combination of impedances that can ensure relatively directivity and obtain a large transmission characteristic S21. Here, in the combination of Z1 = 50Ω, Z2 = 20Ω, etc., the horizontal width of the tapered line becomes too large, and sufficient directivity cannot be obtained. However, the relative dielectric constant of the dielectric substrate is set to 2.

5A, FIG. 5B, FIG. 5C, and FIG. 5D show the electric field distribution on the surface of the dielectric substrate when excited by a tapered microstrip line type directional sensor and the electric field distribution of the substrate cross section at the center of the substrate. The display in cross section shows a range of about 2 cm from the ground conductor surface including the air layer. However, the dielectric constant of the dielectric substrate backed by the conductor plate is 2, and the relative dielectric constant of the dielectric at the top of the sensor is 1. A, B, C, and D show cases where the dielectric substrate layer thickness t is 300 μm, 1 mm, 5 mm, and 8 mm, respectively.
When the layer thickness is thick, the directivity effect can be clearly confirmed, but when the layer thickness is very thin t = 300 μm, the directivity is almost lost. However, the distance between the transmission and reception sensors was set to 20 cm as the distance where the end surfaces on the low impedance side face each other.

FIG. 6 shows the transmission characteristic S21, and FIG. 7 shows the phase characteristic. However, the distance between the transmitting / receiving sensors facing each other is 20 cm, and the relative dielectric constant of the dielectric substrate is 2.
When S21 is 300 μm as compared with the case where the layer thickness is 5 mm, the degradation is 30 dB or more in the 12 GHz band where S21 is maximized. This indicates that the TM surface wave is extremely difficult to be trapped if the dielectric layer thickness is extremely thin. When the layer thickness is small, the phase characteristic also deteriorates due to the influence of reflection, and the linear phase characteristic is broken. However, it can be seen that when the dielectric layer thickness exceeds 5 mm, S21 deteriorates and there is an optimum thickness.

  From the results shown in FIGS. 5 to 7, t = 300 μm, which is the condition of the thickness of the dielectric substrate for achieving low-frequency power feeding, may be accompanied by a large transmission loss and deterioration of reflection characteristics in TM surface wave transmission. I understood.

  Therefore, as the structure of the microstrip line sensor for efficiently exciting the TM surface wave on the conductive plate backed ultrathin dielectric substrate, the shape of the sensor shown in FIG. 3 is selected as Z1 = 120Ω, Z2 = 40Ω, and further above A dielectric having a high dielectric constant (relative dielectric constant = 9.8) was provided. The substrate thickness h of the dielectric is used as a parameter.

  In order to achieve both wireless power feeding and two-dimensional communication, it is necessary to excite the TM surface wave on the surface of the ultrathin dielectric substrate on the low frequency power feeding electrode shown in FIG. The microstrip line sensor structure for efficiently exciting the TM surface wave on the ultrathin dielectric substrate has the microstripline taper type transmission / reception sensor shown in FIG. 3 installed on the surface of the ultrathin dielectric substrate backed by a conductor plate. It is assumed that a dielectric having a high dielectric constant (relative dielectric constant = 9.8) is arranged on the sensor. The TM surface wave electric field distribution on the ultrathin dielectric substrate surface and the substrate cross section when the thickness h of the dielectric on the sensor is used as a parameter (500 μm, 1 mm, 3 mm, 5 mm) are shown in FIGS. This is shown in FIGS. 8C and 8D. In the case of h = 3 mm and 5 mm, directivity can be confirmed. However, the relative dielectric constant of the ultrathin dielectric substrate backed by the conductive plate is 2.0 and the substrate thickness is 300 μm.

  FIG. 9 shows transmission characteristics and FIG. 10 shows phase characteristics with h as a parameter. As a result, in the case where the dielectric substrate thickness t = 300 μm and the relative dielectric constant is 2, if the dielectric thickness of the high dielectric body (relative dielectric constant = 9.8) on the sensor is set to h = 3 mm, t in FIG. 9 and FIG. = 300 μm When comparing the best values, the transmission characteristic S 21 was improved by about 15 dB. When h = 3 mm, the influence of reflection is small and a linear phase characteristic is obtained in the vicinity of 9 GHz which is the transmission band.

  In order to achieve compatibility with low-frequency wireless power feeding, transmission of TM surface waves on the surface of a conductor plate-lined ultrathin dielectric substrate in the form of crossing a 0.5 mm slit shown in FIG. 1 is required. In the transmission / reception sensor of FIG. 3, when the thickness of the high dielectric (relative permittivity = 9.8) on the sensor is 3 mm, the 0.5 mm slit shown in FIG. 1 is vertically crossed once. The electromagnetic field simulation in the case of transmission was performed. FIG. 11 shows the electric field distribution of TM surface waves transmitted across the slit, FIG. 12 shows the transmission characteristics, and FIG. 13 shows the phase characteristics. In the 7-12 GHz band, it was found that the influence of the slits was slight.

In order to solve the problem for achieving both wireless power feeding and two-dimensional communication, an ultra-thin dielectric layer (about approximately one) installed on the substrate surface in the substrate structure as shown in FIG. The TM surface wave is trapped at 300 μm) for transmission and communication.
In particular, as a means for solving the problem of trapping and transmitting TM surface waves on the surface of an ultrathin dielectric material, a high dielectric constant (relative dielectric constant = 9) is formed on the top of the microstripline taper shown in FIG. .8) It is shown that a transmission / reception sensor characterized by installing a dielectric may be used.

The invention's effect

  In a two-dimensional communication system using a floor surface, etc., on which an ultrathin dielectric layer capable of wireless power feeding is provided, the TM surface wave is efficiently excited on the surface of the ultrathin dielectric, The development of a transmission / reception directional sensor that can be trapped greatly increases the effects of multipath due to reflection on the dielectric substrate end face and the increase in transmission loss due to the wave absorber loaded to eliminate the reflection. Can be improved.

  : "Example of floor / wall structure with wireless power supply function"   : "TM surface wave propagating by being trapped on the dielectric surface of the conductor backing the conductor plate"   : "Structure of tapered microstrip line directional sensor"   : "Positional relationship between the transmission / reception directivity sensor and the conductor-backed dielectric substrate"   : "TM surface wave electric field distribution on the dielectric substrate surface lined with a conductive plate when excited by a tapered microstrip line type directional sensor, when layer thickness t = 300 μm"   : “TM surface wave electric field distribution on the dielectric substrate surface lined with a conductive plate when excited by a tapered microstrip line type directional sensor, when the layer thickness is t = 1 mm”   : "TM surface wave electric field distribution on the surface of a dielectric substrate backed by a conductive plate when excited with a tapered microstrip line type directional sensor, when the layer thickness is t = 5 mm"   : "TM surface wave electric field distribution on the surface of a dielectric substrate lined with a taper-shaped microstrip line type directional sensor when the layer thickness is t = 8 mm"   : “Transmission characteristics S21 of the structure of FIGS. 3 and 4”   : “Phase characteristics of the structure of FIGS. 3 and 4”   : “In the case of TM surface wave electric field distribution on the surface of a very thin dielectric substrate backed by a conductive plate, sensor upper dielectric layer thickness h = 0.5 mm”   : "In the case of TM surface wave electric field distribution on the surface of a conductor plate-lined ultrathin dielectric substrate, sensor upper dielectric layer thickness h = 1 mm"   : "In the case of TM surface wave electric field distribution on the surface of a conductor plate-lined ultrathin dielectric substrate, sensor upper dielectric layer thickness h = 3 mm"   : “In the case of TM surface wave electric field distribution on the surface of a very thin dielectric substrate backed by a conductive plate, sensor upper dielectric layer thickness h = 5 mm”   : "TM surface wave transmission characteristic S21 on the surface of a very thin dielectric substrate backed by a conductive plate"   : “Phase characteristics of TM surface wave transmission on the surface of an ultrathin dielectric substrate backed by a conductive plate”   : “TM surface wave electric field distribution when transmitting across the slit shown in FIG. 1 on the surface of an ultrathin dielectric substrate”   : “TM surface wave transmission characteristic S21 when transmitting across the slit shown in FIG. 1 on the surface of the ultrathin dielectric substrate”   : "TM surface wave phase characteristics when transmitting across the slit shown in Fig. 1 on the surface of an ultrathin dielectric substrate"

  The transmission / reception directivity sensor having the structure shown in FIGS. 3 and 4 is arranged at an arbitrary point in a two-dimensional space capable of low-frequency wireless power supply as shown in FIG. 1, and the TM surface wave shown in FIG. 1 is excited on the ultrathin dielectric substrate shown in FIG. 1 to perform two-dimensional floor / wall communication.

Effects of the embodiment

  By using the embodiment of the directivity sensor shown here, it is possible to greatly reduce the influence of reflection on the end face of the substrate, which is a problem in two-dimensional communication using the floor surface, and to reduce transmission loss. In addition, since a two-dimensional communication system compatible with wireless power feeding at a low frequency can be realized, communication can be performed while supplying power to an assistive intelligent walking robot that moves on the floor or the like.

Other embodiments

る波動を意味する。本提案では、誘電体基板表面から垂直方向に基板から離れるにしたがって指数関数的に減衰する。
Ｓ２１ ： ポート１から２への伝送特性を表わすＳパラメーター。
Ｓ１１ ： ポート１での反射特性を表わすＳパラメーター。
テーパー形状 ： インピーダンスを徐々に変化させ（線幅を変化）電磁波を反射少なくスムーズに伝送させる形状。
指向性センサ ： 電磁波をある方向に大きな感度で、励振／検出するセンサ
無指向性センサ ： 電磁波を全方位同じ感度で、励振／検出するセンサ
マイクロストリップライン ： マイクロ波、ミリ波帯で用いられる伝送線路で、中心導体と接地板で誘電体基板を挟んだ構造になっている。
マルチパス ： 電波伝搬において、反射などの影響を受け、希望とする電波以外に複数の経路を介しての電波を受信することにより受信品質を劣化させる。本提案の床面や壁面等の２次元通信システムでも、基板端面などでの反射がマルチパスとなり、受信品質を劣化させる。
ワイヤレス給電 ： 家庭やオフィスにおける電力供給に、一般的にはケーブルを用いる。ケーブルの輻輳や移動物体への電力供給が求められるようになっており、床面や壁面からケーブルを介さずに直接給電する方法が必要になってきている。この要求には、床面や壁面に設置された板状の電極導体から極薄誘電体層を介しての静電結合型や、誘導結合型がある。本提案では、約１ＭＨｚを用いた静電結合型の低周波ワイヤレス給電と２次元通信の両立を提案している。TM surface wave: TM wave is a Transverse Magnetic Wave, which is an electromagnetic wave having no electric field component in the wave traveling direction, has a cutoff frequency, and does not propagate low frequencies including direct current. A surface wave is a wave propagating by being trapped on a surface such as a dielectric, and is an electromagnetic wave that decays exponentially as the distance from the surface increases. The electromagnetic wave used in this patent.

This means the wave. In this proposal, it attenuates exponentially as it moves away from the substrate in the vertical direction from the surface of the dielectric substrate.
S21: S parameter indicating transmission characteristics from port 1 to port 2.
S11: S parameter indicating reflection characteristics at port 1.
Tapered shape: A shape in which impedance is gradually changed (line width is changed) and electromagnetic waves are smoothly transmitted with little reflection.
Directional sensor: Sensor that excites / detects electromagnetic waves with high sensitivity in a certain direction Non-directional sensor: Sensor that excites / detects electromagnetic waves with the same sensitivity in all directions Microstrip line: Transmission used in the microwave and millimeter wave bands The track has a structure in which a dielectric substrate is sandwiched between a central conductor and a ground plate.
Multipath: In radio wave propagation, the reception quality is deteriorated by receiving radio waves through a plurality of routes in addition to the desired radio wave due to the influence of reflection and the like. Even in the proposed two-dimensional communication system such as a floor surface or a wall surface, reflection on the end face of the substrate becomes multipath, which degrades reception quality.
Wireless power supply: Generally, cables are used for power supply in homes and offices. Cable congestion and power supply to moving objects have been demanded, and a method of directly feeding power from a floor surface or a wall surface without using a cable is required. This requirement includes an electrostatic coupling type and an inductive coupling type through a very thin dielectric layer from a plate-like electrode conductor placed on the floor or wall surface. This proposal proposes the coexistence of two-dimensional communication and electrostatic coupling type low-frequency wireless power feeding using about 1 MHz.

Claims (2)

Floor / wall surface 2 characterized by being capable of coexistence with low-frequency wireless power feeding by trapping and transmitting microwave TM surface waves on the surface of a dielectric substrate backed ultrathin (500 μm or less) dielectric substrate Dimensional communication system. In a tapered microstrip line used to provide directivity to the transmission / reception sensor that excites the surface wave on the surface of the ultra-thin dielectric substrate, a high dielectric is formed on the upper surface of the central conductor to efficiently excite the microwave surface wave. 2. The floor / wall two-dimensional communication system according to claim 1, wherein a directional sensor having a structure with a body is used.

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