Radio-wave reflection-plate distortion detection method

Abstract

This radio-wave reflection-plate distortion detection method for detecting distortion of an incident surface includes: in a radio-wave reflection plate in which a plurality of resonance elements, each capable of controlling a phase of a reflected radio wave, are arranged in a lattice on a surface, controlling, for each column or row, phases of radio waves reflected by the resonance elements; measuring an amplitude of a reflected wave reflected by the radio-wave reflection plate; and obtaining a distortion from a reference plane of the surface on the basis of a phase at which the amplitude is maximum, a column at which the amplitude is maximum, and a row at which the amplitude is maximum.

Description

Method for detecting distortion of radio wave reflectors

[0001] An embodiment of the present invention relates to a method for detecting distortion of a radio wave reflector.

[0002] Conventionally, a radio wave reflector has been known that changes the dielectric constant of a liquid crystal element for each area where radio waves are incident, changing the phase of radio waves passing through liquid crystal elements with different dielectric constants, thereby controlling the amplitude, direction, etc. of the reflected radio waves (Patent Document 1).

[0003] Japanese Patent Application Laid-Open No. 2022-156917

[0004] The radio wave reflector described in Patent Document 1 includes a plurality of resonant elements. In order to reflect radio waves having the intended phase, amplitude, direction, etc., it is desirable that the plurality of resonant elements be arranged on one plane in the radio wave reflector.

[0005] However, physical irregularities can occur on the radio wave reflector due to errors in the manufacturing process, changes over time, etc. The occurrence of irregularities becomes particularly noticeable as the radio wave reflector becomes larger. Due to physical irregularities on the radio wave reflector, the incident surface of the radio wave reflector is no longer flat, causing displacement, i.e., distortion, in the incident and reflection directions between multiple resonant elements. As a result, the incident wave will be incident on the radio wave reflector with a phase different from the intended phase, making it impossible to generate the intended reflected wave and potentially reducing the performance of the radio wave reflector.

[0006] In view of the above problems, one object of one embodiment of the present invention is to provide a method for detecting distortion of a radio wave reflector that detects distortion of an incident surface.

[0007] A method for detecting distortion of a radio wave reflector according to one embodiment of the present invention includes controlling the phase of the radio waves reflected by the resonant elements on a surface of the radio wave reflector in a grid pattern, measuring the amplitude of the reflected wave reflected by the radio wave reflector, and determining the distortion from a reference plane of the surface based on the phase at which the amplitude is maximum, the column at which the amplitude is maximum, and the row at which the amplitude is maximum.

[0008] 5 is a plan view showing an example of a radio wave reflector for explaining a method for detecting distortion of a radio wave reflector according to one embodiment of the present invention. FIG. 6 is a partial cross-sectional view showing one state of the radio wave reflector shown in FIG. 1. FIG. 7 is a partial cross-sectional view showing another state of the radio wave reflector shown in FIG. 1. FIG. 8 is a diagram showing the relationship between radio waves incident on the radio wave reflector shown in FIG. 1 and radio waves reflected by the radio wave reflector. FIG. 9 is a diagram explaining an example of a system for implementing a method for detecting distortion of a radio wave reflector according to one embodiment of the present invention. FIG. 10 is another diagram explaining radio waves incident on the radio wave reflector shown in FIG. 1. FIG. 11 is a diagram showing an example of functional blocks of a control device shown in FIG. 5. FIG. 6 is a flowchart explaining a method for detecting distortion of a radio wave reflector according to one embodiment of the present invention. FIG. 7 is another flowchart explaining a method for detecting distortion of a radio wave reflector according to one embodiment of the present invention. FIG. 8 is another flowchart explaining a method for detecting distortion of a radio wave reflector according to one embodiment of the present invention. FIG. 9 is a diagram explaining the phase of a reflected wave measured in a method for detecting distortion of a radio wave reflector according to one embodiment of the present invention. FIG. 10 is another flowchart explaining a method for detecting distortion of a radio wave reflector according to one embodiment of the present invention. 15 is a diagram showing the relationship between the phase, incident wave, and reflected wave shown in FIG. 14. FIG. 15 is a diagram showing another example of the phase shift different from that ... an example of a case where a phase shift of a reflected wave is not detected in a method for detecting distortion of a radio wave reflector according to one embodiment of the present invention. FIG. 15 is a diagram showing an example of a hardware configuration for realizing the control device shown in FIG. 8. FIG. 15 is a diagram showing an example of an incident wave used in a method for detecting distortion of a radio wave reflector according to a modified example. FIG. 15 is a diagram showing another example of an incident wave used in a method for detecting distortion of a radio wave reflector according to another modified example. FIG. 15 is a diagram showing an example of the phase shift of a reflected wave measured in the method for detecting distortion of a radio wave reflector shown in FIGS. 20 and 21.

[0009] Hereinafter, each embodiment of the present invention will be described with reference to the drawings. However, the present invention can be embodied in various forms without departing from the spirit of the present invention, and should not be construed as being limited to the description of the following exemplary embodiments. Furthermore, in the drawings, the width, thickness, shape, etc. of each part may be schematically shown compared to the actual form to clarify the explanation. However, these schematic diagrams are merely examples and do not limit the interpretation of the present invention. Furthermore, in this specification and each drawing, elements that are identical or similar to those described in the previous drawings may be given the same reference numerals, and redundant explanations may be omitted. Note that in this specification, ordinal numbers are used for convenience to distinguish parts, portions, etc., and do not indicate priority or order.

[0010] In the present invention, when a single film is processed to form multiple films, these multiple films may have different functions and roles. However, these multiple films originate from films formed as the same layer in the same process, and have the same layer structure and the same material. Therefore, these multiple films are defined as existing in the same layer. Furthermore, when a single film is processed to form multiple films, they may be distinguished and described as -1, -2, etc. in this specification.

[0011] In this specification and claims, expressions such as "above" and "below" express the relative positional relationship between a structure of interest and another structure. In this specification and claims, when expressing an aspect in which another structure is placed on top of a certain structure, the term "above" is used to include both a case in which another structure is placed directly above the certain structure so as to be in contact with the certain structure, and a case in which another structure is placed above the certain structure via yet another structure, unless otherwise specified.

[0012] First Embodiment A method DM1 for detecting distortion of a radio wave reflector according to one embodiment of the present invention detects distortion of a radio wave reflector 20 included in a radio wave reflecting device 10 shown in Fig. 1. The entire radio wave reflecting device 10 will be described with reference to Fig. 1.

[0013] (Radio wave reflecting device 10) The radio wave reflecting device 10 includes a radio wave reflecting plate 20 that reflects radio waves, and a peripheral region 122 formed on the outside of the radio wave reflecting plate 20. The radio wave reflecting plate 20 includes a dielectric substrate (dielectric layer) 104 and an opposing substrate 106 that faces the dielectric substrate 104, and has a structure in which a liquid crystal layer (not shown) is provided between the dielectric substrate 104 and the opposing substrate 106. The dielectric substrate 104 and the opposing substrate 106 are bonded together with a sealant 128, and a liquid crystal layer (not shown) is provided in the region inside the sealant 128.

[0014] The area of ​​the dielectric substrate 104 is larger than that of the counter substrate 106, and therefore the dielectric substrate 104 extends outward beyond the counter substrate 106. A first drive circuit 124, a second drive circuit 130, and a terminal section 126 are provided in the peripheral region 122. The first drive circuit 124 is a circuit that outputs control signals to the patch electrodes 108, and the second drive circuit 130 is a circuit that outputs scanning signals to the patch electrodes 108. The terminal section 126 is an area for forming a connection with an external circuit, and is connected to, for example, a flexible printed circuit board (not shown). Signals for controlling the first drive circuit 124 and the second drive circuit 130 are input to the terminal section 126.

[0015] 1 , a switching element 134 is provided for each of the four patch electrodes 108. The switching (on and off) of the switching element 134 is controlled by a scanning signal applied to the second wiring 132. When the switching element 134 is turned on, the patch electrode 108 is electrically connected to the first wiring 118 and a control signal is applied to it. The switching element 134 is formed of, for example, a thin-film transistor. With this configuration, it is possible to select a plurality of patch electrodes 108 arranged in the column direction (X-axis direction) for each row, and apply control signals of different voltage levels to each row.

[0016] (Radio wave reflector 20) The radio wave reflector 20 includes a plurality of resonant elements 102. The resonant elements 102 are arranged, for example, in a column direction (the X-axis direction shown in FIG. 1 ) and a row direction (the Y-axis direction shown in FIG. 1 ) intersecting the column direction. Each resonant element 102 is an element formed from a region in which each patch electrode 108 faces a common electrode 110 shared with other resonant elements 102. The radio wave reflector 20 is formed in a flat plate shape, and a plurality of patch electrodes 108 are arranged in a lattice pattern within the surface of the radio wave reflector 20. In each resonant element 102, the direction from the common electrode 110 toward the patch electrode 108 is the Z-axis direction shown in FIG. 1 . The surface on which the patch electrode 108 is arranged is the incident surface of radio waves.

[0017] 2 and 3 are schematic cross-sectional views of one resonant element 102 shown in Fig. 1 taken along a plane parallel to the XY plane passing through A-A'. Fig. 2 shows the resonant element 102 in a state where no voltage is applied between the patch electrode 108 and the common electrode 110 (hereinafter referred to as the "first state"). Fig. 3 shows the resonant element 102 in a state where a constant voltage is applied between the patch electrode 108 and the common electrode 110 (hereinafter referred to as the "second state").

[0018] Between the dielectric substrate 104 and the counter substrate 106, a patch electrode 108, a first alignment film 112a, a liquid crystal layer 114, a second alignment film 112b, and a common electrode 110 are arranged in the direction from the dielectric substrate 104 toward the counter substrate 106 (the -Z direction in FIGS. 2 and 3). The first alignment film 112a covers the patch electrode 108, and the second alignment film 112b covers the common electrode 110. In the resonant element 102, the dielectric substrate 104 can also be considered as a dielectric layer, forming one layer.

[0019] The patch electrode 108 preferably has a shape that is symmetrical with respect to the vertically polarized and horizontally polarized waves of the incident radio wave, and has a square or circular shape in a plan view.

[0020] FIG. 1 illustrates an example of a patch electrode 108 that is square in plan view. The shape of the common electrode 110 is not particularly limited, and it has a shape that extends over substantially the entire surface of the opposing substrate 106 so as to have a larger area than the patch electrode 108. The material for forming the patch electrode 108 and the common electrode 110 is not particularly limited, and they may be formed using conductive metals or metal oxides. A first wiring 118 may be provided on the dielectric substrate 104. The first wiring 118 is connected to the patch electrode 108. The first wiring 118 can be used to apply a control signal to the patch electrode 108. Furthermore, when multiple resonant elements 102 are arranged, the first wiring 118 can be used to electrically connect a patch electrode 108 to an adjacent patch electrode 108.

[0021] A control signal that controls the orientation of liquid crystal molecules in the liquid crystal layer 114 is applied to the patch electrode 108. The control signal is a DC voltage signal or a polarity inversion signal in which positive and negative DC voltages alternate. The common electrode 110 is grounded or receives a voltage at an intermediate level of the polarity inversion signal. Application of the control signal to the patch electrode 108 changes the orientation state of the liquid crystal molecules contained in the liquid crystal layer 114. A liquid crystal material having dielectric anisotropy is used for the liquid crystal layer 114. For example, nematic liquid crystal, smectic liquid crystal, cholesteric liquid crystal, or discotic liquid crystal can be used for the liquid crystal layer 114. The dielectric constant of the liquid crystal layer 114 with dielectric anisotropy changes depending on the change in the orientation state of the liquid crystal molecules. The resonant element 102 can change the dielectric constant of the liquid crystal layer 114 by applying a control signal to the patch electrode 108, thereby delaying the phase of the reflected wave when reflecting radio waves.

[0022] The frequency bands of radio waves reflected by the resonant element 102 include the very high frequency (VHF) band, the ultra-high frequency (UHF) band, the super high frequency (SHF) band, the tremendously high frequency (THF) band, and the extra high frequency (EHF) band. The liquid crystal molecules in the liquid crystal layer 114 change their orientation in response to a control signal applied to the patch electrode 108, but the orientation hardly changes with the frequency of the radio waves irradiated onto the patch electrode 108. Therefore, the resonant element 102 can control the phase of the reflected radio waves without being affected by the radio waves themselves.

[0023] Although not shown in FIGS. 2 and 3 , the dielectric substrate 104 and the counter substrate 106 are bonded together with a sealant. The dielectric substrate 104 and the counter substrate 106 are disposed opposite each other with a gap therebetween, and the liquid crystal layer 114 is provided within the area surrounded by the sealant. The liquid crystal layer 114 is provided to fill the gap between the dielectric substrate 104 and the counter substrate 106. The gap between the dielectric substrate 104 and the counter substrate 106 is 20 to 100 μm, for example, 50 μm. A patch electrode 108, a common electrode 110, a first alignment film 112 a, and a second alignment film 112 b are provided between the dielectric substrate 104 and the counter substrate 106. Therefore, to be precise, the gap between the first alignment film 112 a and the second alignment film 112 b provided on the dielectric substrate 104 and the counter substrate 106, respectively, is the thickness of the liquid crystal layer 114. Although not shown in FIGS. 2 and 3, a spacer may be provided between the dielectric substrate 104 and the opposing substrate 106 to maintain a constant gap therebetween.

[0024] 2 and 3 show a case where the first alignment film 112 a and the second alignment film 112 b are horizontal alignment films. As shown in Fig. 2, when no voltage is applied between the patch electrode 108 and the common electrode 110, the long axes of the liquid crystal molecules 116 in the first state are aligned horizontally to the surfaces of the patch electrode 108 and the common electrode 110 by the first alignment film 112 a and the second alignment film 112 b.

[0025] 3, when a voltage is applied between the patch electrode 108 and the common electrode 110, in the second state, the liquid crystal molecules 116 are affected by the electric field and their long axes are oriented perpendicular to the surfaces of the patch electrode 108 and the common electrode 110. The angle at which the long axes of the liquid crystal molecules 116 are oriented can also be set to a direction intermediate between the horizontal and vertical directions, depending on the magnitude of the control signal applied to the patch electrode 108.

[0026] When the liquid crystal molecules 116 have positive dielectric anisotropy, the dielectric constant is greater in the second state than in the first state. Furthermore, when the liquid crystal molecules 116 have negative dielectric anisotropy, the apparent dielectric constant is smaller in the second state than in the first state. The liquid crystal layer 114, which has dielectric anisotropy, can also be considered a variable dielectric layer. Therefore, the resonant element 102 can utilize the dielectric anisotropy of the liquid crystal layer 114 to control whether or not to delay the phase of the reflected wave RW (see FIG. 4 ).

[0027] 1 , the plurality of first wirings 118 arranged on the radio wave reflecting plate 20 extend into the peripheral region 122 and are connected to a first driving circuit 124. The first driving circuit 124 is capable of outputting control signals of different voltage levels to each of the plurality of first wirings 118. As a result, in the radio wave reflecting plate 20, a control signal is applied to each of the plurality of patch electrodes 108 arranged in the column direction (X-axis direction) and row direction (Y-axis direction), for each column.

[0028] The applied control signal may be held as an electric charge stored in a capacitance (not shown) included in each resonant element 102. According to the radio wave reflector 20, the patch electrodes 108 arranged in the column direction (X-axis direction) can be selected row by row, and a control signal of a different voltage level can be applied to each row.

[0029] 4 is a diagram schematically illustrating how the propagation direction of the reflected wave RW changes depending on the first resonant element 102a and the second resonant element 102b adjacent to the first resonant element 102a. The structures of the first resonant element 102a and the second resonant element 102b are similar to the structure of the resonant element 102 shown in FIGS. 2 and 3. When radio waves are incident on the first resonant element 102a and the second resonant element 102b with the same phase, different control signals (V1≠V2) are applied to the first resonant element 102a and the second resonant element 102b, so the phase of the reflected wave RW2 from the second resonant element 102b changes significantly compared to the phase of the reflected wave RW1 from the first resonant element 102a. As a result, the phase of the reflected wave RW1 reflected by the first resonant element 102a differs from the phase of the reflected wave RW2 reflected by the second resonant element 102b, and the apparent propagation direction of the reflected wave RW changes in a direction inclined relative to the incident wave IW.

[0030] By controlling the amount of phase change by the resonant elements for each column, the reflection direction can be controlled in one axis direction. For example, by controlling the amount of phase change by the resonant elements for each row, the reflection direction can be controlled in another axis direction. Since the voltage can be controlled for each resonant element 102, the reflection direction can be controlled arbitrarily by combining control in the column direction and control in the row direction.

[0031] It is preferable that the resonant element 102 used in the radio wave reflector 20 attenuates the amplitude of the reflected wave RW as little as possible. As is clear from the structure shown in Fig. 4, when a radio wave propagating through the air is reflected by the resonant element 102, the radio wave passes through the dielectric substrate 104 twice. The dielectric substrate 104 is formed of a dielectric material such as glass or resin.

[0032] (Method DM1 for detecting distortion of a radio wave reflector) The radio wave reflector 20 is designed to be flat, but unevenness may occur in some parts due to errors in the manufacturing process, changes over time, etc. This may cause distortion in the radio wave reflector 20, and the surface on which the resonant element 102 is arranged may become curved. Below, a description will be given of a distortion detection system 1 that uses method DM1 for detecting distortion of a radio wave reflector.

[0033] (Distortion Detection System 1) The distortion detection system 1 shown in Fig. 5 includes a radio wave reflecting device 10 including a radio wave reflecting plate 20, a transmitter 41, a transmitting antenna 42, a reflecting mirror 43, a measuring device 31, a receiving antenna 32, and a control device 50. The transmitting antenna 42 is connected to the transmitter 41, which transmits radio waves, and is an antenna that emits radio waves. The receiving antenna 32 is connected to the measuring device 31 and is an antenna that receives radio waves. The measuring device 31 measures the amplitude, phase, frequency, etc. of the reflected wave RW reflected by the radio wave reflecting plate 20 via the receiving antenna 32. The control device 50 is connected to the transmitter 41, the measuring device 31, and the radio wave reflecting device 10, and controls these devices.

[0034] The transmitting antenna 42 connected to the transmitter 41 is, for example, a feed antenna, and the reflector 43 is, for example, a compact range reflector, and a system including the transmitter 41, the transmitting antenna 42, and the reflector 43 constitutes, for example, a compact range system. The radio waves transmitted from the transmitting antenna 42 are reflected by the reflector 43 and become plane waves parallel to the radio wave reflector 20 (the equiphase surface is parallel to the XY plane).

[0035] The surface of the radio wave reflector 20 is ideally flat as shown in Figure 6, and the virtual radio wave reflecting surface consisting of all the resonant elements 102 is on one plane (hereinafter referred to as the "reference plane") RP. Therefore, the equiphase surface IS is a plane, and the incident wave IW whose equiphase surface IS is parallel to the radio wave reflector 20 is incident on the radio wave reflector 20 in the same phase. Below, the dielectric substrate 104 and other parts of the radio wave reflector 20 that are on the incident wave IW side of the reference plane RP will be omitted.

[0036] The radio wave reflector 20 may have partial unevenness due to errors in the manufacturing process, changes over time, etc. For this reason, the surface on which the resonant elements 102 are arranged may be curved rather than flat. Furthermore, even if the surface of the radio wave reflector 20 is flat, the surface of the radio wave reflector 20 is not perpendicular to the direction of the incident wave IW, and therefore the phase of the incident plane wave may not be the same. Below, a case will be described where the surface on which the resonant elements 102 are arranged is a curved surface that is convex toward the incident wave IW side.

[0037] 7 shows the case where the center of the radio wave reflector 20 bulges. The resonator element 102c located near the center protrudes by DL in the direction in which the incident wave IW is incident (+Z direction) compared to the resonator elements 102e located on the periphery. Therefore, a phase shift corresponding to the distance DL occurs between the incident wave IW incident on the resonator element 102c and the incident wave IW incident on the resonator element 102e. Therefore, a phase shift also occurs in the reflected wave RW reflected by the radio wave reflector 20, and the reflected wave RW does not become a plane wave.

[0038] In order to avoid such unintended phase shift, the method DM1 for detecting distortion of a radio wave reflector detects distortion of the radio wave reflector 20 as follows.

[0039] (Functional Blocks of the Control Device 50) As shown in FIG. 8, the control device 50 (see FIG. 5) includes a transmitter control unit 51, an amplitude measurement unit 52, a column memory unit 53, a phase memory unit 54, a radio wave reflecting plate control unit 55, an amplitude memory unit 56, a row memory unit 57, and a distortion detection unit 58. The transmitter control unit 51 and the radio wave reflecting plate control unit 55 control the transmitter 41 (see FIG. 5) and the radio wave reflecting plate 20, respectively, and the amplitude measurement unit 52 measures the reflected wave RW. The column memory unit 53, the phase memory unit 54, the amplitude memory unit 56, and the row memory unit 57 each store information regarding the column, phase, amplitude, and row of the measured reflected wave RW (see FIG. 5). The distortion detection unit 58 detects distortion of the radio wave reflecting plate 20 (see FIG. 5) based on the measured information.

[0040] 9 is a flowchart showing an outline of the method DM1 for detecting distortion of a radio wave reflecting plate. The method DM1 for detecting distortion of a radio wave reflecting plate generally includes the steps of starting transmission of radio waves (S10), determining the phase θi at which the amplitude A of the reflected wave RW is maximized in the column i direction (S20), determining the phase θj at which the amplitude A of the reflected wave RW is maximized in the row j direction (S30), detecting distortion (S40), and terminating transmission of radio waves (S50).

[0041] 8 and 9, in the step of starting transmission (S10), the transmitter control unit 51 controls the transmitter 41 (see FIG. 5) to start supplying power to the transmitting antenna 42 and start transmitting radio waves.

[0042] Next, step S20 shown in Fig. 9 will be described in detail with reference to Fig. 8 and Fig. 10. In step S20, as shown in Fig. 10, for each column i, the phase θi of the resonant element 102 is changed in increments of 10° from 0° to 360°, the amplitude A of the reflected wave RW is measured, and the column i in which the amplitude A is maximum and the phase θi at that time are determined.

[0043] First, the amplitude measurement unit 52 selects the resonant elements 102 arranged in the first column i from among the multiple resonant elements 102 (see FIG. 1) arranged on the radio wave reflector 20 (S201). For example, the amplitude measurement unit 52 stores the value "1" indicating the first column in the column storage unit 53.

[0044] Next, the amplitude measurement unit 52 sets an initial value of the phase (S202). For example, the amplitude measurement unit 52 stores "0" in the phase storage unit 54, which indicates the initial value of the phase, 0°.

[0045] Next, the amplitude measurement unit 52 sets an initial value of the amplitude (S203). For example, the amplitude measurement unit 52 stores "0" in the amplitude storage unit 56, which indicates the initial value of the amplitude.

[0046] The radio wave reflecting plate control unit 55 sets the phase of the selected column i to θi (S204). For example, the radio wave reflecting plate control unit 55 controls the scanning signals of the second wirings 132 of all rows via the second driving circuit 130 to turn on the switching elements 134 of all rows (see FIG. 1). Furthermore, the radio wave reflecting plate control unit 55 applies a control voltage corresponding to the phase θi to the patch electrode 108 for the selected column i via the first driving circuit 124 (see FIG. 1). In this way, the radio wave reflecting plate control unit 55 controls the phase θi of the resonant elements 102 for the selected column i to be different from that of the other columns.

[0047] Next, the amplitude measurement unit 52 measures the amplitude A of the reflected wave RW (S205). For example, the amplitude measurement unit 52 measures the amplitude A of the reflected wave RW (see FIG. 5) reflected by the radio wave reflector 20 and received by the receiving antenna 32.

[0048] Next, the amplitude measurement unit 52 determines whether the measured amplitude A is greater than the maximum amplitude Amax (S206). If the amplitude measurement unit 52 determines that the amplitude A is greater than the maximum amplitude Amax (S206; Yes), the amplitude measurement unit 52 stores the value of the amplitude A as the maximum amplitude Amax in the amplitude memory unit 56 (S207), stores the value of column i as the value imax of the column at which the amplitude A is maximum in the column memory unit 53 (S208), and stores the value of the phase θi as the value θmax of the phase at which the amplitude A is maximum in the phase memory unit 54 (S209).

[0049] On the other hand, if the amplitude measurement unit 52 does not determine that the amplitude A is greater than the maximum amplitude Amax (S206; No), steps S207, S208, and S209 are not executed, and step S210 following step S209 is executed.

[0050] When the amplitude measurement unit 52 has completed measurement of the amplitude A of the reflected wave RW for one phase θi, the amplitude measurement unit 52 changes the phase θi. For example, the amplitude measurement unit 52 reads out the value of the phase θi stored in the phase memory unit 54, adds 10 to the read phase θi, and stores the result in the phase memory unit 54 again, thereby increasing the phase θi by 10° (S210).

[0051] Next, the amplitude measurement unit 52 determines whether the phase θi is equal to 360° to check whether the measurement has been completed for all phases (S211). If the amplitude measurement unit 52 does not determine that the phase θi is 360° (S211; No), the process returns to initialization of the amplitude A (S203).

[0052] If the amplitude measurement unit 52 determines that the phase θi is 360° (S211; Yes), the measurement for all phases has been completed, and the amplitude measurement unit 52 measures the amplitude A for another column. The amplitude measurement unit 52 determines whether the column for which the amplitude A was measured is the final column (S212), and if it determines that it is the final column (S212; Yes), the process of step S20 is terminated and step S30 is executed (see FIG. 9 ).

[0053] If the amplitude measurement unit 52 does not determine that the column in which the amplitude A was measured is the last column (S212; No), it selects the next column i+1 of the resonant elements 102 of the radio wave reflector 20 (S213). For example, the amplitude measurement unit 52 reads out the value of column i stored in the column storage unit 53, adds "1" to the read column i, and stores the result in the column storage unit 53 again, thereby selecting the next column i+1. Then, the amplitude measurement unit 52 returns to step S202 and continues the process.

[0054] In step S202, the initial value of the phase θi is not limited to 0°. For example, the initial value of the phase θi may be −180°. The phase θi does not have to be increased in increments of 10°, but may be increased in increments of 30°, for example. Furthermore, the increase in the phase θi does not have to be a constant value; it may be increased finely for phases near the initial value and roughly for phases farther from the initial value. For example, the phase θi may be changed as follows: 0°, 1°, 2°, 5°, 10°, 30°, 60°, 90°, 180°, and 270°.

[0055] Furthermore, the selection of column i (S213) does not have to be sequential selection of adjacent columns from left to right. For example, odd-numbered columns 1, 3, and 5 may be selected sequentially, and then even-numbered columns 2 and 5 may be selected.

[0056] 11 is a schematic diagram showing the results of executing the process shown in step S20 (see FIG. 9). By executing step S20, the phase θi is changed for each column i, and the phase at which the amplitude A of the reflected wave RW is maximized is measured. In this example, it can be seen that when i = 1 or 5, the maximum amplitude A is obtained when θi = 0°, when i = 2 or 4, the maximum amplitude A is obtained when θi = 5°, and when i = 3, the maximum amplitude A is obtained when θi = 10°.

[0057] Details of step S30 shown in Fig. 9 will be described with reference to Fig. 8 and Fig. 12. In step S30, as shown in Fig. 12, for each row j, the phase θj of the resonant element 102 is changed in increments of 10° from 0° to 360°, the amplitude A of the reflected wave RW is measured, and the row j at which the amplitude A is maximum and the phase θj at that time are determined.

[0058] First, the amplitude measurement unit 52 selects the resonant elements 102 arranged in the first row j from among the multiple resonant elements 102 (see FIG. 1) arranged on the radio wave reflector 20 (S301). For example, the amplitude measurement unit 52 stores the value "1" indicating the first row in the row storage unit 57.

[0059] Next, the amplitude measurement unit 52 sets an initial value of the phase (S302). For example, the amplitude measurement unit 52 stores "0" in the phase storage unit 54, which indicates the initial value of the phase, 0°.

[0060] Next, the amplitude measurement unit 52 sets an initial value of the amplitude (S303). For example, the amplitude measurement unit 52 stores "0" in the amplitude storage unit 56, which indicates the initial value of the amplitude.

[0061] The radio wave reflecting plate control unit 55 sets the phase of the selected row j to θj (S304). For example, the radio wave reflecting plate control unit 55 controls the scanning signal of the second wiring 132 of the selected row j via the second driving circuit 130 to turn on the switching element 134 of the row j (see FIG. 1). The radio wave reflecting plate control unit 55 also applies a control voltage corresponding to the phase θi to the patch electrode 108 for all columns via the first driving circuit 124 (see FIG. 1). In this way, the radio wave reflecting plate control unit 55 controls the phase θj of the resonant element 102 of the selected row j to be different from that of the other rows.

[0062] Next, the amplitude measurement unit 52 measures the amplitude A of the reflected wave RW (S305). For example, the amplitude measurement unit 52 measures the amplitude A of the reflected wave RW (see FIG. 5) reflected by the radio wave reflector 20 and received by the receiving antenna 32.

[0063] Next, the amplitude measurement unit 52 determines whether the measured amplitude A is greater than the maximum amplitude Amax (S306). If the amplitude measurement unit 52 determines that the amplitude A is greater than the maximum amplitude Amax (S306; Yes), the amplitude measurement unit 52 stores the value of the amplitude A as the maximum amplitude Amax in the amplitude memory unit 56 (S307), stores the value of row j as the value jmax of the row at which the amplitude A is maximum in the row memory unit 57 (S308), and stores the value of the phase θj as the value θmax of the phase at which the amplitude A is maximum in the phase memory unit 54 (S309).

[0064] On the other hand, if the amplitude measurement unit 52 does not determine that the amplitude A is greater than the maximum amplitude Amax (S306; No), steps S306, S307, and S308 are not executed, and step S310, which is the next step after step S309, is executed.

[0065] When the amplitude measurement unit 52 has completed measurement of the amplitude A of the reflected wave RW for one phase θj, the amplitude measurement unit 52 changes the phase θj. For example, the amplitude measurement unit 52 reads out the value of the phase θj stored in the phase memory unit 54, adds 10 to the read phase θj, and stores the result in the phase memory unit 54 again, thereby increasing the phase θj by 10° (S310).

[0066] Next, the amplitude measurement unit 52 determines whether the phase θj is equal to 360° to check whether measurements have been completed for all phases (S311). If the amplitude measurement unit 52 does not determine that the phase θj is 360° (S311; No), the process returns to initialization of the amplitude A (S303).

[0067] If the amplitude measurement unit 52 determines that the phase θj is 360° (S311; Yes), the measurement for all phases has been completed, and the amplitude measurement unit 52 measures the amplitude A for another row. The amplitude measurement unit 52 determines whether the row for which the amplitude A was measured is the last row (S312), and if it determines that it is the last row (S312; Yes), the process of step S30 is terminated and step S40 is executed (see FIG. 9 ).

[0068] If the amplitude measurement unit 52 does not determine that the row in which the amplitude A was measured is the last row (S312; No), it selects the next row j+1 from the resonant elements 102 of the radio wave reflector 20 (S313). For example, the amplitude measurement unit 52 reads out the value of row j stored in the row storage unit 57, adds "1" to the read-out row j, and stores the result in the row storage unit 57 again, thereby selecting the next row j+1. Then, the amplitude measurement unit 52 returns to step S302 and continues the process.

[0069] In step S302, the initial value of the phase θj is not limited to 0°. For example, the initial value of the phase θj may be −180°. The phase θj does not have to be increased in increments of 10°, but may be increased in increments of 30°, for example. Furthermore, the increase in the phase θj does not have to be a constant value; it may be fine for phases near the initial value and coarse for phases farther from the initial value. For example, the phase θj may be changed as follows: 0°, 1°, 2°, 5°, 10°, 30°, 60°, 90°, 180°, and 270°.

[0070] Furthermore, the selection of row j does not have to be performed by sequentially selecting adjacent rows from top to bottom. For example, odd-numbered rows 1, 3, and 5 may be selected sequentially, and then even-numbered rows 2 and 5 may be selected.

[0071] 13 is a schematic diagram showing the results of executing the process shown in step S30 (see FIG. 9). By executing step S20, the phase θj is changed for each row j, and the phase at which the amplitude A of the reflected wave RW is maximized is measured. In this example, it is shown that when j = 1 or 5, the maximum amplitude A is obtained when θj = 0°, when j = 2 or 4, the maximum amplitude A is obtained when θj = 5°, and when j = 3, the maximum amplitude A is obtained when θj = 10°.

[0072] By executing the processes from step S10 to step S30, the phases θi and θj at which the amplitude measured for each row j and column i of each resonant element 102 included in the radio wave reflector 20 is maximized are obtained.

[0073] The distortion detector 58 detects the distortion of the radio wave reflector 20 from the phases θi and θj at which the amplitude measured for each row j and column i is maximized (S40 in FIG. 9).

[0074] The distortion detector 58 (see FIG. 8) measures the distortion of the radio wave reflector 20, i.e., the distance DL (see FIG. 7) between the surface on which the resonant element 102 is arranged and the reference plane RP (see FIG. 6), for example, by the following procedure.

[0075] The distortion detection unit 58 determines the position (i, j) where the phase θi for each column i and the phase θj for each row j match, and the phase θ at that time. Note that "match" includes not only the case where they match exactly, but also the case where the difference is equal to or less than a certain value.

[0076] FIG. 14 is an explanatory diagram showing the phase θi (θj) overlapping the resonant element 102 arranged at a position where the phase θi for each column i and the phase θj for each row j coincide with each other.

[0077] The distortion detection unit 58 calculates the displacement DA (distance DL in FIG. 7 ) of the resonant element 102 at the position (i, j) where the phase θi for each column i and the phase θj for each row j coincide. The distortion detection unit 58 calculates the displacement DA by, for example, performing at least one of the following calculations:

[0078] When the phase shift is Δθ and the wavelength of the incident wave IW is λ, the displacement DA corresponding to the phase shift Δθ can be calculated by the following equation.

[0079] DA=λ×Δθ / 360° (Formula 1)

[0080] The wavelength λ of the incident wave IW can be calculated using the following formula based on the propagation velocity v of the wave in the medium and its frequency f.

[0081] λ=v / f (Formula 2)

[0082] Therefore, the distortion detection unit 58 may obtain the displacement DA by performing the calculation shown as Equation 2 instead of Equation 1. By combining Equation 1 and Equation 2, the displacement DA can be obtained as follows.

[0083] DA=(v×Δθ) / (f×360°) (Equation 3)

[0084] Therefore, the distortion detection unit 58 can calculate the displacement DA based on, for example, the propagation speed v of waves in the air, the frequency f of the incident wave IW set in the transmitter 41 shown in Figure 5, and the difference Δθ between the reference phase and the phase at which the amplitude is maximum, as shown in Figure 15.

[0085] In this embodiment, the initial values ​​of the phases θi and θj are 0°, and therefore the distortion detection unit 58 calculates Δθ in the above formulas 1 and 3, assuming that the phase shift Δθ is equal to θ. If the phase reference value θr is different from 0°, the distortion detection unit 58 may calculate the phase shift Δθ by performing the following calculation.

[0086] Δθ=θ−θr (Formula 4)

[0087] By performing the above processing, the distortion detection unit 58 can detect the position on the radio wave reflector 20 identified by column i, row j, and the deviation of the resonant element 102 at that position from the reference plane RP (see Figure 6).

[0088] In addition to the above-described processing, the distortion detection unit 58 may perform, for example, interpolation processing on a three-dimensional plane to detect deviations of all the resonant elements 102 included in the radio wave reflector 20 from the reference plane RP.

[0089] Referring again to FIGS. 8 and 9, in the step of ending transmission (S50), the transmitter control unit 51 stops the supply of power to the transmitting antenna 42 and ends the transmission of radio waves.

[0090] The above-described method DM1 for detecting distortion of a radio wave reflector can detect a misalignment of the resonator element 102 that occurred during the manufacturing process or during use. Therefore, by irradiating an incident wave, the phase of which has been corrected in advance to correspond to the misalignment, onto the radio wave reflector 20, the phase of the reflected wave RW can be adjusted, and the reflected wave RW can be reflected in a desired direction.

[0091] In other words, the coordinates at which the displacement DA is maximum are the positions at which the most protruding resonant element 102 is disposed on the radio wave reflector 20 .

[0092] The method DM1 for detecting distortion of a radio wave reflector can calculate not only the position where the most protruding resonant element 102 is located, but also the position where the most recessed resonant element 102 is located. For example, Fig. 16 shows an example in which the phase sign is measured inversely to that in Fig. 14 in each column i and each row j. According to the measurement results in Fig. 16, it can be detected that the radio wave reflector 20 is most recessed near its center.

[0093] FIG. 17 shows an example of detecting the deviation in which the resonant element 102 located at i=j=1 is most protruding.

[0094] As shown in FIG. 18, according to the radio wave reflector distortion detection method DM1, the phase at which the amplitude is maximum is 0° regardless of the position at which it is placed. In other words, it is possible to detect that there is no phase shift and therefore to detect that there is no distortion in the radio wave reflector 20.

[0095] In the above description, one maximum value of the amplitude A is found for each column and each row, but two values ​​may be found for each column: the maximum value and the next largest value.

[0096] The frequency of the plane wave may be constant or may be changed for each measurement or during the measurement. For example, when the control device 50 detects an interfering radio wave, the control device 50 may perform control to generate an incident wave IW of a different frequency suitable for the measurement.

[0097] Whether a certain portion of the radio wave reflecting plate 20 is more convex than other portions may be determined from the sign (positive or negative) of the displacement DA and known criteria.

[0098] The above-described processing can be performed by the control device 50 shown in Fig. 8. The functions of the control device 50 can be realized by, for example, an information processing device 60 shown in Fig. 19.

[0099] The information processing device 60 is a computer including, for example, a processor 61 , a main memory device 62 , an auxiliary memory device 63 , a communication interface 64 , and an internal bus 65 .

[0100] The techniques described in the embodiments can be written as a program that can be executed by a computer onto a storage medium such as a magnetic disk, an optical disk, a magneto-optical disk, or a semiconductor memory, and applied to various devices. A computer that realizes the present disclosure reads the program stored in the storage medium, and executes the above-mentioned processes by having its operation controlled by the program.

[0101] The method DM1 for detecting distortion of a radio wave reflector according to the first embodiment uses a plane wave with no inclination as the incident wave IW, but the incident wave IW does not have to be a plane wave with no inclination. For example, the method DM2 for detecting distortion of a radio wave reflector according to the first modification uses a plane wave that is inclined with respect to the radio wave reflector 20 as the incident wave IW.

[0102] Specifically, as shown in Fig. 20, the incident wave IW used in the method DM2 for detecting distortion of a radio wave reflector is a plane wave having an equiphase surface IS tilted at an angle φ with respect to the XY plane. The tilted plane wave can be generated by, for example, a beamforming antenna.

[0103] Although the methods DM1 and DM2 for detecting distortion of a radio wave reflector according to the first embodiment and the first modification use a plane wave as the incident wave IW, the incident wave IW does not have to be a plane wave.

[0104] Specifically, as shown in Fig. 21, the incident wave IW used in the method DM3 for detecting distortion of a radio wave reflector according to the second modification is a spherical wave whose equiphase surface IS is spherical. The spherical wave can be generated by, for example, a beamforming antenna. The reflected wave RW may be measured by, for example, a near-field measurement method.

[0105] According to the methods DM2 and DM3 for detecting distortion of a radio wave reflector according to the first and second modifications, distortion can be detected even when the distortion is parallel to the rows of the radio wave reflector 20, as shown in FIG. 22, for example.

[0106] Although the embodiments have been described above using the methods DM1, DM2, and DM3 for detecting distortion of a radio wave reflector as examples, the scope of application of the present invention is not limited to methods for detecting distortion of a radio wave reflector. The distortion detection method according to the present disclosure may also be applied to methods for detecting distortion of a reflector related to waves other than radio waves, for example.

[0107] Although preferred embodiments have been described above, the present disclosure is not limited to such embodiments. The contents disclosed in the embodiments are merely examples, and various modifications are possible within the scope of the present disclosure. Appropriate modifications made within the scope of the present disclosure naturally fall within the technical scope of the present disclosure. Furthermore, the above-described embodiments can be implemented in appropriate combinations as long as they are not mutually contradictory. Furthermore, even if there are other effects and advantages different from those achieved by the aspects of the above-described embodiments, those that are clear from the description in this specification or that can be easily predicted by a person skilled in the art are naturally considered to be achieved by the present invention.

[0108] 1: distortion detection system, 10: radio wave reflecting device, 20: radio wave reflecting plate, 31: measuring device, 32: receiving antenna, 41: transmitter, 42: transmitting antenna, 43: reflector, 50: control device, 51: transmitter control unit, 52: amplitude measurement unit, 53: column memory unit, 54: phase memory unit, 55: radio wave reflecting plate control unit, 56: amplitude memory unit, 57: row memory unit, 58: distortion detection unit, 60: information calculation device, 61: processor, 62: main memory unit, 63: auxiliary memory unit, 64: communication interface, 65: internal bus, 102, 102c, 102e: resonance element, 102a: first resonator element, 102b: second resonator element, 104: dielectric substrate, 106: opposing substrate, 108: patch electrode, 110: common electrode, 112a: first alignment film, 112b: second alignment film, 114: liquid crystal layer, 116: liquid crystal molecules, 118: first wiring, 122: peripheral region, 124: first drive circuit, 126: terminal portion, 128: seal material, 130: second drive circuit, 132: second wiring, 134: switching element, DM1, DM2, DM3: method for detecting distortion of radio wave reflector, IW: incident wave, RW1, RW2, RW: reflected wave

Claims

1. A method for detecting distortion of a radio wave reflector, in which a plurality of resonant elements, each capable of controlling the phase of the reflected radio waves, are arranged in a lattice pattern on the surface, the method comprising: controlling the phase of the reflected radio waves for each column or row; measuring the amplitude of the reflected waves reflected by the radio wave reflector; and determining the displacement of the resonant element, arranged at the position where the column and row, which coincide in phase to maximize the amplitude, intersect from a reference plane of the surface.

2. The method for detecting distortion of a radio wave reflector according to claim 1, wherein controlling the phase of the radio waves reflected by the resonant elements for each column or each row is to control the phase of the resonant elements for each column so that it differs from the phase of the resonant elements in other columns or rows.

3. A method for detecting distortion of a radio wave reflector as described in claim 1, wherein controlling the phase of the radio waves reflected by the resonant elements for each column or each row includes repeatedly changing the phase between 0° and 360° for all of the columns and all of the rows.

4. The method for detecting distortion of a radio wave reflector according to claim 1, wherein the radio waves incident on the radio wave reflector are plane waves.

5. The method for detecting distortion of a radio wave reflector according to claim 4, wherein the equiphase surface of the plane wave is parallel to the radio wave reflector.

6. A method for detecting distortion of a radio wave reflector according to claim 4, wherein the equiphase surface of the plane wave is inclined with respect to the radio wave reflector.

7. The method for detecting distortion of a radio wave reflector according to claim 1, wherein the radio waves incident on the radio wave reflector are spherical waves.

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