Liquid crystal phase modulation device, phase shifter, phased array antenna device, and radio wave reflector

Abstract

This phase modulator comprises a first electrode, a second electrode, and a liquid crystal layer which contains a plurality of liquid crystal molecules and is disposed between the first electrode and the second electrode, wherein: the height of the liquid crystal layer from the first electrode to the second electrode is 30-50 μm; and in a planar view of a first surface which includes the first electrode, the liquid crystal layer, and the second electrode and which intersects the in-plane direction of the first electrode, at least two liquid crystal molecules disposed adjacently in a direction parallel to the in-plane direction of the first electrode and having different orientations are included.

Description

Technical Field

[0001] One embodiment of the present invention relates to a phase modulation device using a liquid crystal material. In particular, one embodiment of the present invention relates to a phase shifter using a liquid crystal material, or a phased array antenna device having the phase shifter. Alternatively, one embodiment of the present invention relates to a metamaterial radio wave reflector using a liquid crystal material.

Background Art

[0002] A phased array antenna device has the characteristic that when a high-frequency signal is applied to some or all of a plurality of antenna elements, the radiation directivity of the antenna can be controlled while fixing the direction of the antenna in one direction by controlling the amplitude and phase of each high-frequency signal. A phased array antenna device uses a phase shifter to control the phase of the high-frequency signal applied to the antenna element.

[0003] As a method of the phase shifter, there are various methods such as a method of physically changing the length of a transmission line to change the phase of a high-frequency signal, a method of changing the impedance in the middle of a transmission line to change the phase of a high-frequency signal by reflection, and a method of generating a signal having a desired phase by controlling and synthesizing the gains of amplifiers that amplify two signals having different phases. In addition to these, Patent Document 1 discloses a method that utilizes the property peculiar to a liquid crystal material that the dielectric constant changes depending on the applied voltage as an example of a phase shifter.

[0004] On the other hand, a metamaterial reflector that utilizes the dielectric anisotropy of a liquid crystal and gives a phase change to the reflected wave of the radio wave incident on a patch electrode is known. By applying different voltages to adjacent patch electrodes, the amount of phase change at each can be made different, and it can be made to behave as if the reflection direction of the radio wave has changed. For example, Patent Document 2 discloses a metasurface in which the reflection phase is electronically reconfigured and electronically adjustable.

Prior Art Documents

[0005] [Patent Document 1] Japanese Patent Application Publication No. 11-103201 [Patent Document 2] Special Publication No. 2019-530387 [Non-patent literature]

[0006] [Non-Patent Document 1] Y. Iimura, S. Kobayashi, T. Sugiyama, Y. Toko, T. Hashimoto, K. Kato, “EO Characteristics of Amorphous and Super-Multidomain TN-LCDs Prepared by a Non-Rubbing Method” The institute of Image Information and Television Engineers Technical Report, Volume 18 (Issue 43), pp.31-36, 1994. [Overview of the project] [Problems that the invention aims to solve]

[0007] In phase modulation devices such as phase shifters and metamaterial reflectors using liquid crystals, obtaining a sufficient amount of phase shift requires a liquid crystal layer thickness (cell gap) that is more than 10 times greater than that of liquid crystal displays, resulting in a problem of slow response times of several seconds. There is a need for phase modulation devices that can achieve faster response times. [Means for solving the problem]

[0008] A phase modulation device according to one embodiment of the present invention comprises a first electrode, a second electrode, and a liquid crystal layer comprising a plurality of liquid crystal molecules and disposed between the first electrode and the second electrode, wherein the distance between the first electrode and the second electrode is 30 μm or more and 50 μm or less, and includes at least two liquid crystal molecules that are arranged adjacent to each other in a direction parallel to the in-plane direction of the first electrode and have different orientations from each other, in a plan view of the first surface including the first electrode, the liquid crystal layer and the second electrode, intersecting the in-plane direction of the first electrode. [Brief explanation of the drawing]

[0009] [Figure 1A] The configuration of a phase modulation device according to one embodiment of the present invention is shown, and a plan view is shown of the first substrate and the second substrate in a superimposed state. [Figure 1B] This shows a plan view of the first substrate of a phase modulation device according to one embodiment of the present invention. [Figure 1C] This shows a plan view of the second substrate of a phase modulation device according to one embodiment of the present invention. [Figure 2A] Figure 1A shows the structure of a phase modulation device according to one embodiment of the present invention, and a cross-sectional end view corresponding to the line A1-A2 is shown. [Figure 2B] This shows a magnified view of the area enclosed by the dashed line B in Figure 2A. [Figure 3A] The structure of the phase modulation device according to this embodiment is shown, and a cross-sectional end view corresponding to the line A1-A2 in Figure 1A is shown. [Figure 3B] This shows a magnified view of the area enclosed by the dashed line B in Figure 3A. [Figure 4A] The structure of the phase modulation device according to this embodiment is shown, and a cross-sectional end view corresponding to the line A1-A2 in Figure 1A is shown. [Figure 4B] The figure shows the amorphous liquid crystal layer observed from the first electrode (quoted from Non-Patent Document 1). [Figure 5A] The configuration of a phase modulation device according to one embodiment of the present invention is shown, and a plan view is shown of the first substrate and the second substrate in a superimposed state. [Figure 5B] This shows a plan view of the first substrate of a phase modulation device according to one embodiment of the present invention. [Figure 5C] The plan view of the second substrate of the phase modulation device according to an embodiment of the present invention is shown. [Figure 6] The cross-sectional end view corresponding to the A1-A2 line of FIG. 5A of the phase modulation device according to an embodiment of the present invention is shown. [Figure 7A] The configuration of the phase modulation device according to an embodiment of the present invention is shown, and the plan view of the state where the first substrate and the second substrate are overlapped is shown. [Figure 7B] The plan view of the first substrate of the phase modulation device according to an embodiment of the present invention is shown. [Figure 7C] The plan view of the second substrate of the phase modulation device according to an embodiment of the present invention is shown. [Figure 8] The cross-sectional end view corresponding to the A1-A2 line of FIG. 7A of the phase modulation device according to an embodiment of the present invention is shown. [Figure 9] One configuration example of the phased array antenna device 1000 according to an embodiment of the present invention is shown. [Figure 10] The cross-sectional structure corresponding to the B1-B2 line in FIG. 9 is shown. [Figure 11] One configuration example of a radio wave reflector using a phase modulation device corresponding to a patch electrode is shown. [Figure 12A] One configuration example of a radio wave reflector using a phase modulation device corresponding to a patch electrode is shown. [Figure 12B] It is a plan view obtained by enlarging the broken line portion E in FIG. 12A. [Figure 13] The cross-sectional end view showing an example of a TFT to be arranged on the radio wave reflector is shown. [Figure 14A] The plan view of the first electrode is shown. [Figure 14B] The plan view of the second electrode is shown. [Figure 15] A modified example of the arrangement of the first electrode is shown.

Embodiments for Carrying Out the Invention

[0010] Embodiments of the present invention will be described below with reference to the drawings, etc. However, the present invention can be implemented in many different forms, and is not limited to the embodiments described below. In order to make the explanation clearer, the drawings may schematically represent the width, thickness, shape, etc. of each part compared to the actual embodiment, but these are merely examples and do not limit the interpretation of the present invention. In addition, in this specification and each figure, elements similar to those described above with respect to previously shown figures are denoted by the same reference numerals (or numerals followed by a, b, etc.), and detailed explanations may be omitted as appropriate. Furthermore, the letters "1st," "2nd," etc., attached to each element are convenient indicators used to distinguish each element, and do not particularly limit the explanation. Without further explanation, it has no further meaning.

[0011] In this specification, when a member or region is said to be "above (or below)" another member or region, unless otherwise specified, this includes not only cases where it is directly above (or directly below) the other member or region, but also cases where it is above (or below) the other member or region, that is, cases where another component is included between them above (or below) the other member or region. In the following description, unless otherwise specified, in a cross-sectional view, the area above the orthodox position of the figure is referred to as "above" or "above," the surface viewed from "above" or "above" is referred to as the "top surface" or "top side," and the opposite is referred to as "below," "below," "bottom surface," or "bottom side."

[0012] Figure 1A shows a plan view of a phase modulation device 100 according to one embodiment of the present invention. The phase modulation device 100 has a structure in which a first electrode 106 and a second electrode 108 are arranged to face each other. The first electrode 106 and the second electrode 108 have substantially the same flat plate shape when viewed from the first electrode 106 to the second electrode 108, or when viewed from the second electrode 108 to the first electrode 106, but the first electrode 106 and the second electrode 108 are not limited to this. For example, if the second electrode 108 is a ground electrode, the width of the first electrode 106 in the Y-axis direction (the second direction described later) may be shorter than that of the second electrode 108.

[0013] Figure 1B shows a plan view of the first substrate 102. The first substrate 102 is a flat plate-shaped substrate with an insulating surface. The first electrode 106 is provided on this insulating surface. In Figure 1B, as an example, a structure is shown in which the first electrode 106 is substantially the same as that of the first substrate 102, but the width of the first electrode 106 in the Y-axis direction may be shorter than that of the first substrate 102.

[0014] The first electrode 106 can be fabricated by forming at least one conductive film on the surface of the first substrate 102. Alternatively, the first electrode 106 may be fabricated by patterning the formed conductive film by etching so that its width in the Y-axis direction is shorter than that of the first substrate 102 or the second electrode 108. The first substrate 102 may be made of an insulating material such as glass or ceramic, and an insulating surface may be formed by its own physical properties, or an insulating surface may be formed by forming an insulating film on its surface. The conductive film is a metal film such as aluminum or copper, and can be fabricated by vacuum deposition or sputtering. In addition, a metal foil may be used as the first electrode 106 instead of a conductive film.

[0015] Figure 1C shows a plan view of the second substrate 104. The second substrate 104 is a flat plate-shaped substrate with an insulating surface. A second electrode 108 is provided on almost the entire surface of one main surface of the second substrate 104. The second electrode 108 is also formed of a conductive film.

[0016] Figure 2A shows the cross-sectional structure of portion A enclosed by a dashed line, in relation to the cross-sectional structure along the line A1-A2 shown in Figure 1A. A liquid crystal layer 115 is positioned between the first electrode 106 and the second electrode 108. The liquid crystal layer 115 is filled with liquid crystal; in other words, the liquid crystal layer 115 contains multiple liquid crystal molecules 114. The height d of the liquid crystal layer 115 in the Z-axis direction from the first electrode 106 to the second electrode 108 is between 30 μm and 50 μm. As shown in Figure 2A, in a plan view of the cross-section (hereinafter also referred to as the first plane) including the first electrode 106, the liquid crystal layer 115, and the second electrode 108, which intersects the in-plane direction of the first electrode 106, two liquid crystal molecules 114 positioned adjacent to each other in a direction parallel to the in-plane direction of the first electrode 106 have different orientations. The phase modulation device 100 is characterized by controlling the orientation of the liquid crystal molecules 114 such that the orientations of at least two adjacent liquid crystal molecules 114 are different.

[0017] In one embodiment, the liquid crystal molecule 114a is tilted with respect to the first electrode 106 (first tilt angle), and the liquid crystal molecule 114b, which is arranged adjacent to the first electrode 106 in a direction parallel to the in-plane direction of the first electrode 106, is tilted with respect to the first electrode 106 at a second tilt angle different from the first tilt angle.

[0018] Such orientation control of liquid crystal molecules 114 can be achieved in one embodiment by arranging a convex structure 112 on the phase modulation device 100. Multiple first convex structures 112a protruding toward the second electrode 108 are arranged on the first electrode 106. Multiple second convex structures 112b protruding toward the first electrode 106 are arranged on the second electrode 108. It is possible to control the orientation of liquid crystal molecules 114 by arranging multiple first convex structures 112a on the first electrode 106. Therefore, even in a configuration without the second convex structures 112b, it is possible to control the orientation of liquid crystal molecules 114.

[0019] Figure 2B is an enlarged view showing the convex structure 112 enclosed by the dashed line B shown in Figure 2A. Note that the convex structure 112 shown in Figure 2B is applied to the first convex structure 112a and the second convex structure 112b. The convex structure 112 has a triangular cross-section when viewed in cross-section on the first plane. The convex structure 112 extends in a first direction (X-axis direction) parallel to the in-plane direction of the first electrode 106 and has a plurality of triangular prism-shaped structures arranged in a second direction (Y-axis direction) perpendicular to the first direction. In one embodiment, the triangular cross-section is an isosceles triangle with an inclination angle θ of 3° to 5° with respect to the triangular base. The triangular cross-section has a height h of 1 / 20 to 1 / 10 of the height d of the liquid crystal layer 115 (h = d / 20 to d / 10).

[0020] Furthermore, as shown in Figure 2A, the first convex structure 112a and the second convex structure 112b are arranged opposite each other. However, the corner of the first convex structure 112a (first corner) that protrudes toward the second electrode 108 is separated from the corner of the second convex structure 112b (second corner) that protrudes toward the first electrode 106 by a predetermined distance l with respect to the second direction (Y-axis direction). In other words, the perpendicular line from the first corner toward the second electrode 108 is parallel to the perpendicular line from the second corner toward the first electrode 106 and does not coincide. Due to this arrangement of the first convex structure 112a and the second convex structure 112b, the area in which multiple liquid crystal molecules 114 are arranged from the first electrode 106 toward the second electrode 108 is defined by the width l. In this embodiment, the width l of the compartment is smaller than the height d of the liquid crystal layer 115 (l <d)。

[0021] For example, when the height d of the liquid crystal layer 115 is 30 μm to 50 μm, the convex structure 112 may have a triangular cross-section with a base of 34 to 57 μm, an inclination angle of 3 to 5°, and a height of 3 μm. Alternatively, the convex structure 112 may have a triangular cross-section with a base of 5.7 μm, an inclination angle of 3 to 5°, and a height of 0.3 μm to 0.5 μm.

[0022] While the orientation control of liquid crystal molecules 114 is a known technique in liquid crystal display devices, for example, liquid crystal display devices are not designed with a liquid crystal layer 115 height of 30 μm to 50 μm, as is the case with the phase modulation device 100. Such a thickness of liquid crystal layer 115 is a structure unique to the phase modulation device 100. Furthermore, in liquid crystal display devices where visibility is required, liquid crystal molecules 114 are not arranged in sections with a width l smaller than the height d of the liquid crystal layer 115. Such orientation control of liquid crystal molecules 114 using small sections is a technique that has not been used conventionally. In the phase modulation device 100, because the orientation of liquid crystal molecules 114 is controlled by such small sections, unprecedented high-speed phase modulation control can be achieved. In this embodiment, the amount of change in dielectric constant can be maximized.

[0023] Such a convex structure 112 can be realized by laminating a photosensitive organic film and an alignment film. As the material for the photosensitive organic film, known resins used as photosensitive organic films in organic planarization films included in the array substrate of liquid crystal display devices, such as acrylic resins and polyimide resins, can be used. A resin such as polyimide can be applied to the surfaces of the first electrode 106 and the second electrode 108, and after photosensitization and development, a convex structure can be formed, and then the convex structure 112 in which the liquid crystals are aligned can be formed using a rubbing method.

[0024] Figure 3A shows a cross-sectional end view of the first face of a phase modulator 200 with a modified convex structure 212, which is a variation of the convex structure 112. Figure 3B is an enlarged view showing the convex structure 212 enclosed by the dashed line B shown in Figure 3A. Note that the convex structure 212 shown in Figure 3B is applied to the first convex structure 212a and the second convex structure 212b. The convex structure 212 has a triangular cross-section when viewed in cross-section on the first face, but its base is smaller than that of the convex structure 112, and it is a protrusion placed on the first electrode 106.

[0025] The convex structure 212 extends in a first direction (X-axis direction) parallel to the in-plane direction of the first electrode 106 and has a plurality of triangular prism-shaped structures arranged in a second direction (Y-axis direction) perpendicular to the first direction. In one embodiment, the triangular cross-section only needs to have a height h (h=d / 20~d / 10) of the height d of the liquid crystal layer 215, and the length of the base and the inclination angle are not particularly limited.

[0026] Furthermore, as shown in Figure 3A, the first convex structure 212a and the second convex structure 212b are arranged opposite each other. However, the corner of the first convex structure 212a (first corner) that protrudes toward the second electrode 108 is separated from the corner of the second convex structure 212b (second corner) that protrudes toward the first electrode 106 by a predetermined distance l with respect to the second direction (Y-axis direction). In other words, the perpendicular line from the first corner toward the second electrode 108 is parallel to the perpendicular line from the second corner toward the first electrode 106 and does not coincide. With this arrangement of the first convex structure 212a and the second convex structure 212b, the area in which multiple liquid crystal molecules 114 are arranged from the first electrode 106 toward the second electrode 108 is defined by the width l. In this embodiment, the width l of the compartment is smaller than the height d of the liquid crystal layer 215 (l <d)。

[0027] Since such a convex structure 212 can be fabricated using the same materials and manufacturing methods as the convex structure 112, a detailed explanation will be omitted.

[0028] The orientation control of the liquid crystal molecules 114 described above can also be achieved in one embodiment by amorphousizing the liquid crystal layer. Figure 4A shows a cross-sectional end view of the first surface of the phase modulation device 300 in which the liquid crystal layer 315 has been amorphous. Figure 4B is a view of the amorphous liquid crystal layer 315 observed from the first electrode 106 (quoted from Non-Patent Literature 1). The interference fringes observed in Figure 4B indicate the boundaries, i.e., compartments, of adjacent liquid crystal molecules 114 with different orientations. The liquid crystal layer 315 has a structure in which the liquid crystal molecules 114 are randomly oriented. Another characteristic of the liquid crystal layer 315 is that the width l1 of the compartments is different from the width l2 of adjacent compartments, and the liquid crystal layer 315 as a whole does not show regularity. Also, the height d of the liquid crystal layer 315 is 30 μm to 50 μm, and in this embodiment as well, the widths l1 and l2 of the compartments are smaller than the height d of the liquid crystal layer 315 (l <d)。

[0029] In this specification, "randomly oriented structure" means that the orientation of the liquid crystal molecules 114 contained in the liquid crystal layer 315 does not show any overall regularity, and does not exclude the possibility that liquid crystal molecules with the same orientation may be located adjacent to each other in microscopic observation.

[0030] Such a liquid crystal layer 315 can be realized by applying an alignment film to cover the surface of either or both of the first electrode 106 and the second electrode 108, then, without performing any alignment treatment such as rubbing, sealing liquid crystal molecules 114 in the space between the first electrode 106 and the second electrode 108, heating to an isotropic phase, and then rapidly cooling to form a chiral nematic layer. At least the alignment film is placed on the first electrode 106.

[0031] In this embodiment, by amorphousizing the liquid crystal layer 315, the width l of the compartment is made smaller than the height d of the liquid crystal layer 315, thereby enabling high-speed orientation control of the liquid crystal molecules 114.

[0032] An embodiment using the arrangement of a first electrode 406 and a second electrode 408 as a method for forming compartments in the liquid crystal layer will be described. Figure 5A shows a plan view of a phase modulation device 400 according to one embodiment of the present invention. In this embodiment, the first electrode 406 and the second electrode 408 have a strip-like structure. Furthermore, in a plan view in the direction from the first electrode 406 toward the second electrode 408, the orientation of the liquid crystal molecules 114 is controlled by shifting the arrangement of the first electrode 406 and the second electrode 408, thereby generating an electric field at an angle with respect to the first electrode 406.

[0033] The details will be explained with reference to Figures 5B and 5C. Figure 5B shows a plan view of the first substrate 402. The configuration of the first substrate 402 may be the same as that of the first substrate 102, and a detailed explanation will be omitted. The first electrode 406 has a plurality of linear portions (first linear portions) 416 that extend in a first direction (X-axis direction) parallel to the in-plane direction of the first electrode 406 and are arranged in a second direction (Y-axis direction) perpendicular to the first direction. The first electrode 406 also has slit portions (first slit portions) 406S1 arranged between each of the plurality of first linear portions 416. The first electrode 406 has a different shape from the first electrode 106 described above, but its material and manufacturing method may be the same as that of the first electrode 106, and a detailed explanation will be omitted.

[0034] Figure 5C shows a plan view of the second substrate 404. The configuration of the second substrate 404 may be the same as that of the second substrate 104, and a detailed explanation is omitted. The second electrode 408 comprises a plurality of second filamentous portions 418 that extend in a first direction (X-axis direction) and are arranged in a second direction (Y-axis direction). The second electrode 408 also comprises second slit portions (408S1 and 408S2) arranged between the plurality of second filamentous portions 418. The shape of the second electrode 408 differs from that of the second electrode 108 described above, but its material and manufacturing method may be the same as that of the second electrode 108, and a detailed explanation is omitted.

[0035] Refer to Figure 6. Figure 6 shows the cross-sectional structure of portion A enclosed by a dashed line, in relation to the cross-sectional structure along the line A1-A2 shown in Figure 5A. A liquid crystal layer 415 is positioned between the first electrode 406 and the second electrode 408. The liquid crystal layer 415 is filled with liquid crystal; in other words, the liquid crystal layer 415 contains multiple liquid crystal molecules 114. The height d of the liquid crystal layer 415 in the Z-axis direction from the first electrode 406 to the second electrode 408 is between 30 μm and 50 μm.

[0036] In the phase modulation device 400, the width of the first filament 416 in the second direction (Y-axis direction) is the same as the width of the second filament 418 in the second direction. In the first electrode 406, the widths W1 in the second direction of the first slit portions 406S1, which are arranged between the first filament portions 416, are the same. Therefore, the first electrode 406 is formed by arranging the first filament portions 416 at equal intervals in the second direction. On the other hand, in the second electrode 408, the widths W2 in the second direction of the second slit portion 408S1, which are arranged between the second filament portions 418, and the widths W3 in the second direction of the third slit portion 408S2 are different from each other. In the second electrode 408, the relationship w2 > w3 holds. Also, the second slit portion 408S1 and the third slit portion 408S2 are arranged alternately in the second direction.

[0037] Furthermore, in the phase modulation device 400, the relationship w2 > w1 > w3 holds. Therefore, as shown in Figure 5A, in the phase modulation device 400, in a plan view from the first electrode 406 toward the second electrode 408, the multiple first linear portions 416 are arranged to overlap only a portion of the multiple second linear portions 418 in the second direction (Y-axis direction). Note that the configuration of the first electrode 406 and the configuration of the second electrode 408 may be reversed.

[0038] In the phase modulation device 400, a section in which a plurality of liquid crystal molecules 114 oriented from the first electrode 406 toward the second electrode 408 are arranged is defined by the width l due to the arrangement of the first electrode 406 and the second electrode 408 like this. In the present embodiment, the width l of the section is smaller than the height d of the liquid crystal layer 415 (l < d). In a plan view in the direction from the first electrode toward the second electrode, at positions where the first slit portion 406S1 and the second slit portion 408S1 overlap, and at positions where the first slit portion 406S1 and the third slit portion 408S2 overlap, since no phase change of the liquid crystal molecules 114 occurs, it is preferable to reduce w1, w2, and w3 within the range where sections can be formed in the liquid crystal layer 415.

[0039] The arrangement of the first electrode 406 and the second electrode 408 described in the phase modulation device 400 is an arrangement that would not be selected in a liquid crystal display device that requires visibility, and is a structure peculiar to the phase modulation device 400 designed for a liquid crystal layer 415 with a height of 30 μm to 50 μm. In the phase modulation device 400, since the liquid crystal molecules 114 are controlled in orientation by such small sections, a hitherto unprecedented high-speed phase modulation control can be realized.

[0040] In the phase modulation device 400, a method of controlling the orientation of the liquid crystal molecules 114 by adjusting the widths of the second slit portion 408S1 and the third slit portion 408S2 when the width of the first slit portion 406S1 is constant has been described. In the phase modulation device 500, a method of controlling the orientation of the liquid crystal molecules 114 by adjusting the position where the first electrode 506 and the second electrode 508 overlap in a plan view when the widths of the first slit portion 506S1 and the second slit portion 508S1 are the same will be described.

[0041] Figure 7A shows a plan view of a phase modulation device 500 according to one embodiment of the present invention. In this embodiment, the first electrode 506 and the second electrode 508 have a strip-like structure. Furthermore, in a plan view in the direction from the first electrode 506 toward the second electrode 508, the orientation of the liquid crystal molecules 114 is controlled by shifting the arrangement of the first electrode 506 and the second electrode 508, thereby generating an electric field at an angle to the first electrode 506.

[0042] The details will be explained with reference to Figures 7B and 7C. Figure 7B shows a plan view of the first substrate 502. The configuration of the first substrate 502 may be the same as that of the first substrate 102, and a detailed explanation will be omitted. The first electrode 506 has a plurality of linear portions (first linear portions 516) that extend in a first direction (X-axis direction) parallel to the in-plane direction of the first electrode 506 and are arranged in a second direction (Y-axis direction) perpendicular to the first direction. The first electrode 506 also has slit portions (first slit portions) 506S1 arranged between each of the plurality of first linear portions 516. The first electrode 506 has a different shape from the first electrode 106 described above, but its material and manufacturing method may be the same as that of the first electrode 106, and a detailed explanation will be omitted.

[0043] Figure 7C shows a plan view of the second substrate 504. The configuration of the second substrate 504 may be the same as that of the second substrate 104, and a detailed explanation is omitted. The second electrode 508 comprises a plurality of second filamentous portions 518 that extend in a first direction (X-axis direction) and are arranged in a second direction (Y-axis direction). The second electrode 508 also comprises second slit portions 508S1 that are arranged between the plurality of second filamentous portions 518. The shape of the second electrode 508 differs from that of the second electrode 108 described above, but its material and manufacturing method may be the same as that of the second electrode 108, and a detailed explanation is omitted.

[0044] Refer to Figure 8. Figure 8 shows the cross-sectional structure of portion A enclosed by a dashed line, in relation to the cross-sectional structure along the line A1-A2 shown in Figure 7A. A liquid crystal layer 515 is positioned between the first electrode 506 and the second electrode 508. The liquid crystal layer 515 is filled with liquid crystal; in other words, the liquid crystal layer 515 contains multiple liquid crystal molecules 114. The height d of the liquid crystal layer 515 in the Z-axis direction from the first electrode 506 to the second electrode 508 is between 30 μm and 50 μm.

[0045] In the first electrode 506, the width ws1 in the second direction of the first slit portion 506S1 positioned between the first filament portions 516 is the same. Similarly, in the second electrode 508, the width ws2 in the second direction of the second slit portion 508S1 positioned between the second filament portions 518 is the same. Furthermore, the relationship ws1=ws2 holds. On the other hand, in the phase modulation device 500, the width we1 in the second direction (Y-axis direction) of the first filament portion 516 constituting the first electrode 506 and the width we2 in the second direction (Y-direction) of the second filament portion 518 constituting the second electrode 508 are the same, and the relationship we1=we2 holds.

[0046] As shown in Figure 7A, in the phase modulation device 500, in a plan view from the first electrode 506 toward the second electrode 508, the first linear portion 516 partially overlaps with the two second linear portions 518. Furthermore, the second linear portions 518 are arranged so that partially overlap with the two first linear portions 516. Note that the configuration of the first electrode 506 and the configuration of the second electrode 508 may be reversed. In addition, it is preferable to arrange them so that the overlap width of each is constant in order to equalize the response speed in the plane.

[0047] In the phase modulation device 500, a section in which a plurality of liquid crystal molecules 114 directed from the first electrode 506 to the second electrode 508 are arranged is defined by the width l due to the arrangement of the first electrode 506 and the second electrode 508. In the present embodiment, the width l of the section is smaller than the height d of the liquid crystal layer 515 (l < d). In a plan view in the direction from the first electrode 506 to the second electrode 508, at positions where the first slit portion 506S1 and the second strip portion 518 overlap, and at positions where the second slit portion 508S1 and the first strip portion 516 overlap, since no phase change of the liquid crystal molecules 114 occurs, it is preferable to reduce ws1 and ws2 within the range where a section can be formed in the liquid crystal layer 515.

[0048] The arrangement of the first electrode 506 and the second electrode 508 described in the phase modulation device 500 is an arrangement that is not selected in a liquid crystal display device that requires visibility, and is a structure peculiar to the phase modulation device 500 designed for a liquid crystal layer 515 with a height of 30 μm to 50 μm. In the phase modulation device 500, in order to control the orientation of the liquid crystal molecules 114 with such a small section, it is possible to realize an unprecedented high-speed phase modulation control.

[0049] [Phase Array Antenna Device] The phase modulation device described in each of the above embodiments can be used as a phase shifter. By using the phase modulation device as a phase shifter, a phased array antenna device that realizes a high response speed can be configured. FIG. 9 shows a configuration example of a phased array antenna device 1000 in which the phase modulation device 100 is used as a phase shifter. FIG. 9 shows a plan view of the phased array antenna device 1000. FIG. 10 shows a cross-sectional structure corresponding to the B1 - B2 line in FIG. 9. Hereinafter, the description will be made with reference to FIGS. 9 and 10.

[0050] The phased array antenna device 1000 includes a phase modulator 100 and antenna elements 1130. Multiple antenna elements 1130 are arranged in a linear, arc-shaped, or planar manner to form an antenna element array. The phase modulator 100 is provided corresponding to each of the multiple antenna elements 1130. The phased array antenna device 1000 also has a phase control circuit (not shown). The phase control circuit has the function of outputting a signal to control the phase of the phase modulator 100.

[0051] Figures 9 and 10 show the case where the phased array antenna device 1000 is for transmission. The phased array antenna device 1000 has terminals 1160 connected to each of the first electrodes 106, which are microstrip lines. Each terminal 1160 is connected to a distributor 1180. The distributor 1180 is connected to an oscillator 1200. The high-frequency signal output from the oscillator 1200 is distributed to each phase modulation device 100 by the distributor 1180.

[0052] The electromagnetic waves radiated from each of the multiple antenna elements 1130 are coherent. Therefore, the electromagnetic waves radiated from each of the multiple antenna elements 1130 form wavefronts with aligned phases. The phase of the electromagnetic waves radiated from the antenna elements 1130 is adjusted by the phase modulation device 100. The phase modulation device 100 controls the phase of the high-frequency signal radiated as an electromagnetic wave by a phase control circuit (not shown). Although the line width of the phase modulation device 100 is widened to reduce losses in the first electrode 106, which is a microstrip line, the convex structure 112 is placed between it and the second electrode 108, which is a ground conductor layer, thereby achieving a high response speed for the liquid crystal. The same effect can be obtained when the phased array antenna device 1000 is used for receiving.

[0053] In the phased array antenna device described above, an example using phase modulation device 100 was shown, but the phased array antenna device may be configured using any of the phase modulation devices 200 to 500 described above.

[0054] [Radio wave reflector] By using the phase modulation device described in each of the embodiments above as a patch electrode, a metamaterial reflector that achieves a high response speed can be constructed. Figure 11 shows an example of a radio wave reflector 2000 using the phase modulation device 100 in correspondence with the patch electrode. Figure 11 shows a plan view of the radio wave reflector 2000 with uniaxial reflection control. The radio wave reflector 2000 is arranged such that the array substrate 2100 and the opposing substrate 2130 face each other, and a liquid crystal layer 115 is placed between the array substrate 2100 and the opposing substrate 2130. The liquid crystal layer 115 is sealed by a seal 2150. Multiple first electrodes 106 are arranged on the array substrate 2100 in a first direction (X-axis direction), and multiple first electrodes 106 are also arranged in a second direction (Y-axis direction) perpendicular to the first direction. Multiple first electrodes 106 arranged in the first direction are electrically connected by a fine line pattern 2410. The drive circuit 2170 and the fine line pattern 2410 are electrically connected by wiring 2195. The radio wave reflector 2000 also has a reflection axis 2300 parallel to the first direction.

[0055] The second electrode 108 in the phase modulation device 100 is positioned on the opposing substrate 2130. In one embodiment, the second electrode 108 may be positioned over the entire region of the opposing substrate 2130 corresponding to the region where the first electrode 106 is positioned.

[0056] In the radio wave reflector 2000, the same signal is input to a row in the direction of the first electrode 106 (first direction), which is electrically connected by the thin line pattern 2410. Therefore, all the patch electrodes in a row parallel to the reflection axis 2300, enclosed by the dashed line in Figure 11, are electrically connected to each other.

[0057] In this embodiment, the first electrodes 106 are arranged in an array as square, circular, annular, rectangular frame (hollow rectangle), or cross-shaped patch electrodes that are symmetrical with respect to the first and second directions. By electrically connecting the first electrodes 106 in a direction parallel to the reflection axis, the behavior for vertical polarization and horizontal polarization is adjusted to be equal, thereby achieving high sensitivity to the target wavelength. Furthermore, by using the phase modulation device according to this embodiment as patch electrodes, a high response speed can be achieved.

[0058] The radio wave reflector 2000 described above had only one reflection axis 2300, so the reflection angle could only be controlled in the direction with the reflection axis 2300 as the axis of rotation. The radio wave reflector 3000 with two-axis reflection control will be described below. Figure 12A shows an example configuration of the radio wave reflector 3000 using a phase modulation device 100 corresponding to patch electrodes. Figure 12A shows a plan view of the radio wave reflector 3000 with two-axis reflection control. The radio wave reflector 3000 is arranged so that the array substrate 3100 and the opposing substrate 3130 face each other, and a liquid crystal layer 115 is placed between the array substrate 3100 and the opposing substrate 3130. The liquid crystal layer 115 is sealed by a seal 3150. Multiple first electrodes 106 are arranged on the array substrate 3100 in a first direction (X-axis direction), and multiple first electrodes 106 are also arranged in a second direction (Y-axis direction) perpendicular to the first direction. Multiple first electrodes 106 arranged in the first direction are electrically connected by a fine wire pattern 3410. The signal line drive circuit 3170 and the fine wire pattern 3410 are electrically connected by wiring 3195. The radio wave reflector 3000 also has a reflection axis 3300 parallel to the first direction.

[0059] Furthermore, the multiple first electrodes 106 arranged in the second direction are electrically connected by a fine-line pattern 3430. The fine-line pattern 3430 is electrically connected to the scan line drive circuit 3190. The radio wave reflector 3000 also has a reflection axis 3310 parallel to the second direction.

[0060] Figure 12B is a magnified plan of the dashed line E in Figure 12A. The fine line patterns 3410 and 3430 are connected to the thin-film transistor (TFT) 3450. Figure 13 is a cross-sectional end view showing an example of the TFT 3450. The TFT 3450 has a structure in which, for example, a first substrate 102, an undercoat layer 1510, a gate electrode 1530, a bottom gate insulating film 1550, an oxide semiconductor layer 1570, a first connection wiring layer 1590, a top gate insulating film 1610, a back gate electrode 1630, a passivation film 1650, a second connection wiring layer 1670, a signal line 1690, and an insulating film 1710 are sequentially stacked. The TFT3450 is constructed by sequentially stacking an overcoat layer 1730, an insulating film 1750, a first electrode 106, a first convex structure 112a, a liquid crystal layer 115, a second convex structure 112b, a second electrode 108, and a second substrate 104.

[0061] The undercoat layer 1510 may be composed of, for example, a silicon oxide film. The bottom gate insulating film 1550 may be composed of, for example, a SiN / SiO laminated structure. The gate electrode 1530 may be composed of, for example, molybdenum, tungsten, or an alloy thereof. The top gate insulating film 1610 may be composed of, for example, a silicon oxide film. The first connection wiring layer 1590 and the second connection wiring layer 1670 may be composed of, for example, a Ti / Al / Ti laminated structure or a Mo / Al / Mo laminated structure. The passivation film 1650 may be composed of, for example, a silicon nitride film. The insulating film 1710 may be composed of, for example, a silicon oxide film or a silicon nitride film. The first electrode 106 may be composed of, for example, a Ti / Al / Ti laminated structure or a Mo / Al / Mo laminated structure. The second electrode 108 may be composed of, for example, molybdenum, tungsten, or an alloy thereof.

[0062] In Figure 13, TFT3450 is shown as a dual-gate TFT using an oxide semiconductor, but amorphous silicon or low-temperature polysilicon (LTPS) may also be used. Furthermore, while Figure 13 shows an example of longitudinal electric field drive, transverse electric field drive may also be used.

[0063] Since the radio wave reflector 3000 has a reflection axis 3300 parallel to the first direction and a reflection axis 3310 parallel to the second direction, the reflection angle can be controlled in all directions in front of the radio wave reflector depending on the setting of the phase distribution, which is a combination of the direction with the reflection axis 3300 as the axis of rotation and the direction with the reflection axis 3310 as the axis of rotation.

[0064] The second electrode 108 in the phase modulation device 100 is positioned on the opposing substrate 3130. In one embodiment, the second electrode 108 may be positioned over the entire region of the opposing substrate 3130 corresponding to the region where the first electrode 106 is positioned.

[0065] In the radio wave reflector 3000, multiple first electrodes 106 are connected to multiple TFTs 3450. This configures the radio wave reflector 3000 to apply individually independent drive voltages to the liquid crystal layer 115 from the corresponding first electrodes 106 via each TFT 3450.

[0066] In this embodiment, the first electrodes 106 are arranged in an array as square, circular, annular, rectangular frame, or cross-shaped patch electrodes that are symmetrical with respect to the first and second directions. By electrically connecting the first electrodes 106 in a direction parallel to the reflection axis, the behavior for vertical polarization and horizontal polarization is adjusted to be equal, thereby achieving high sensitivity to the target wavelength. Furthermore, by using the phase modulation device according to this embodiment as patch electrodes, a high response speed can be achieved.

[0067] In the above-described example of a radio wave reflector, an example using a phase modulation device 100 was shown, but a radio wave reflector may be constructed using any of the phase modulation devices 200 to 500 described above.

[0068] An example of applying the above-described phase modulation device 400 to a radio wave reflector 2000 or radio wave reflector 3000 will now be described. Figure 14A shows a plan view of the first electrode 706. Figure 14B shows a plan view of the second electrode 708. In addition, in Figure 14A, a configuration in which four first electrodes 706 are arranged and one second electrode 708 is arranged opposite them is also possible.

[0069] Figure 15 shows a modified arrangement of the first electrodes. The first electrodes 806x and 806y may be arranged alternately in a checkerboard pattern. Although not shown in the figure, in this case, the second electrodes are also arranged with their orientations alternating one by one to correspond to the first electrodes 806x and 806y. [Explanation of Symbols]

[0070] 100 Phase modulation device, 102 First substrate, 104 Second substrate, 106 First electrode, 108 Second electrode, 112 Convex structure, 112a First convex structure, 112b Second convex structure, 114 Liquid crystal molecule, 114a Liquid crystal molecule, 114b Liquid crystal molecule, 115 Liquid crystal layer, 200 Phase modulation device, 212 Convex structure, 212a First convex structure, 212b Second convex structure, 215 Liquid crystal layer, 300 Phase modulation device, 315 Liquid crystal layer, 400 Phase modulation device, 402 First substrate, 404 Second substrate, 406 First electrode, 406S1 First slit portion, 408 Second electrode, 408S1 Second slit portion, 408S2 Third slit portion, 415 Liquid crystal layer, 416 416 First fringe section, 418 Second fringe section, 500 Phase modulation device, 502 First substrate, 504 Second substrate, 506 First electrode, 506S1 First slit section, 508 Second electrode, 508S1 Second slit section, 515 Liquid crystal layer, 516 First fringe section, 517 Third fringe section, 518 Second fringe section, 706 First electrode, 708 Second electrode, 806x First electrode, 806y First electrode, 1000 Phased array antenna device, 1130 Antenna element, 1160 Terminal section, 1180 Distributor, 1200 Oscillator, 1510 Undercoat layer, 1530 Gate electrode, 1550 Bottom gate insulating film, 1570 Oxide semiconductor layer, 1590 1610 First connection wiring layer, 1630 Top gate insulating film, 1650 Back gate electrode, 1670 Passivation film, 1670 Second connection wiring layer, 1690 Signal line, 1710 Insulating film, 1730 Overcoat layer, 1750 Insulating film, 2000 Radio wave reflector, 2019 Special specification, 2100 Array substrate, 2130 Opposing substrate, 2150 Seal, 2170 Drive circuit, 2195 Wiring, 2300 Reflection axis, 2410 Fine line pattern, 3000 Radio wave reflector, 3100 Array substrate, 3130 Opposing substrate, 3150 Seal, 3170 Signal line drive circuit, 3190 Scan line drive circuit, 3195 Wiring, 3300 Reflection axis, 3310 Reflection axis, 3410 Fine line pattern, 3430 Fine line pattern

Claims

1. A first electrode, a second electrode, and a liquid crystal layer comprising a plurality of liquid crystal molecules, disposed between the first electrode and the second electrode, A plurality of first convex structures are arranged on the first electrode and protrude toward the second electrode, Equipped with, The height of the liquid crystal layer extending from the first electrode to the second electrode is 30 μm or more and 50 μm or less. In a plan view of the first surface, which includes the first electrode, the liquid crystal layer, and the second electrode, intersecting the in-plane direction of the first electrode, it includes at least two liquid crystal molecules arranged adjacent to each other in a direction parallel to the in-plane direction of the first electrode and having different orientations from each other. A phase modulation device in which the plurality of first convex structures have a triangular cross-section in a cross-sectional view of the first plane, extend in a first direction parallel to the in-plane direction of the first electrode, and have a plurality of triangular prism-shaped structures arranged in a second direction perpendicular to the first direction.

2. The phase modulation device according to claim 1, comprising, on the first surface, a liquid crystal molecule having a first inclination angle with respect to the first electrode, and a liquid crystal molecule arranged adjacent to it in a direction parallel to the in-plane direction of the first electrode and having a second inclination angle different from the first inclination angle.

3. The second electrode further comprises a plurality of second convex structures arranged on the second electrode and protruding toward the first electrode, The plurality of second convex structures have a triangular cross-section in cross-sectional view on the first plane, extend in a first direction parallel to the in-plane direction of the first electrode, and have a plurality of triangular prism-shaped structures arranged in a second direction perpendicular to the first direction. The phase modulation device according to claim 1, wherein the first corners of the plurality of first convex structures protruding toward the second electrodes and the second corners of the plurality of second convex structures protruding toward the first electrodes are separated by a predetermined distance with respect to the second direction.

4. The phase modulation device according to claim 1, wherein, in a plan view of the first surface, the triangular cross-section has a height of 1 / 20 to 1 / 10 of the height of the liquid crystal layer.

5. The phase modulation device according to claim 4, wherein, in a plan view of the first surface, the triangular cross-section has an inclination angle of 3° to 5° with respect to the triangular base surface.

6. A first electrode, a second electrode, and a liquid crystal layer comprising a plurality of liquid crystal molecules and disposed between the first electrode and the second electrode, The height of the liquid crystal layer extending from the first electrode to the second electrode is 30 μm or more and 50 μm or less. In a plan view of the first surface, which includes the first electrode, the liquid crystal layer, and the second electrode, intersecting the in-plane direction of the first electrode, it includes at least two liquid crystal molecules arranged adjacent to each other in a direction parallel to the in-plane direction of the first electrode and having different orientations from each other. The first electrode comprises a plurality of first linear portions extending in a first direction parallel to the in-plane direction of the first electrode and arranged in a second direction perpendicular to the first direction, and a first slit portion arranged between each of the plurality of first linear portions, The second electrode comprises a plurality of second filamentous portions extending in the first direction and arranged in the second direction, and second slit portions arranged between the plurality of second filamentous portions, A phase modulation device in which, in a plan view in the direction from the first electrode toward the second electrode, the plurality of first linear portions each superimpose only a portion of the plurality of second linear portions in the second direction.

7. The second electrode has a third slit portion whose width in the second direction is different from that of the second slit portion. The phase modulation device according to claim 6, wherein in the second electrode, the second slit portion and the third slit portion are arranged alternately in the second direction.

8. The phase modulation device according to claim 6, wherein, in a plan view from the first electrode toward the second electrode, one of the plurality of first linear portions partially overlaps with two of the plurality of second linear portions.

9. A phase modulation device according to any one of claims 1 to 8, A phase shifter in which the first electrode is a microstrip line and the second electrode is a ground conductor layer.

10. A phased array antenna apparatus having a phase shifter as described in claim 9.

11. A radio wave reflector including a phase modulation device according to any one of claims 1 to 8, An array substrate in which multiple first electrodes are arranged in a first direction of a surface intersecting the first surface and in a second direction perpendicular to the first direction, A radio wave reflector comprising: an opposing substrate on which the second electrode is arranged, positioned opposite to the region of the array substrate on which the multiple first electrodes are arranged.

12. The radio wave reflector according to claim 11, wherein a plurality of the first electrodes arranged in the first direction are electrically connected.

13. The radio wave reflector according to claim 11, wherein each of the plurality of first electrodes is connected to a plurality of arranged transistors, and an independent drive voltage is applied to each of the transistors.

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