Optical element and lighting device including the same

Abstract

The optical element is provided with a first liquid crystal cell, a second liquid crystal cell, a third liquid crystal cell, and a fourth liquid crystal cell arranged in this order so as to overlap each other. Each of the first liquid crystal cell, the second liquid crystal cell, the third liquid crystal cell, and the fourth liquid crystal cell includes: a plurality of first electrodes arranged in a stripe shape and extending in a first extending direction; a first alignment film on the plurality of first electrodes; a liquid crystal layer on the first alignment film; a second alignment film on the liquid crystal layer; and a plurality of second electrodes on the second alignment film, arranged in a stripe shape, and extending in a second extension direction, the plurality of second electrodes intersecting the plurality of first electrodes. The further detailed structure is described in the specification.

Description

Technical Field

[0001] One embodiment of the present invention relates to an optical element and a lighting device including the optical element. For example, one embodiment of the present invention relates to a lighting device including a light source and an optical element capable of arbitrarily controlling an illumination area of ​​light from the light source. Background Art

[0002] In recent years, the following lighting devices have been developed: by using an optical element containing liquid crystals to control the light emitted from a light source, the irradiation area and irradiation distance of the light source can be controlled. For example, Patent Document 1 discloses an optical element having a liquid crystal layer and a pair of comb-shaped electrodes. By forming a potential difference between the pair of comb-shaped electrodes, the orientation of liquid crystal molecules in the liquid crystal layer changes and a refractive index distribution is formed in the liquid crystal layer. By appropriately controlling the refractive index distribution, the liquid crystal layer functions as a lens.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2014-160277 Summary of the invention

[0006] Technical problem to be solved by the invention

[0007] One of the technical problems of one embodiment of the present invention is to provide an optical element capable of changing the light distribution state of light incident from a light source, and a lighting device including the optical element. Alternatively, one of the technical problems of one embodiment of the present invention is to provide an optical element capable of changing the light distribution state while suppressing the coloring of the emitted light as much as possible, and a lighting device including the optical element.

[0008] Solutions for solving technical problems

[0009] One embodiment of the present invention is an optical element, comprising a first liquid crystal unit, a second liquid crystal unit, a third liquid crystal unit, and a fourth liquid crystal unit, which are sequentially arranged in an overlapping manner. The first liquid crystal unit, the second liquid crystal unit, the third liquid crystal unit, and the fourth liquid crystal unit each have: a plurality of first electrodes arranged in a stripe shape and extending along a first extension direction; a first alignment film on the plurality of first electrodes; a liquid crystal layer on the first alignment film; a second alignment film on the liquid crystal layer; and a plurality of second electrodes located on the second alignment film, arranged in a stripe shape and extending along a second extension direction intersecting the first extension direction. In each of the first liquid crystal unit, the second liquid crystal unit, the third liquid crystal unit, and the fourth liquid crystal unit, the first alignment film and the second alignment film are configured to align liquid crystal molecules contained in the liquid crystal layer in first and second alignment directions intersecting each other, respectively, when no voltage is applied to the plurality of first electrodes and the plurality of second electrodes, and the angle between the first extension direction and the first alignment direction is within 10°, and the angle between the second extension direction and the second alignment direction is within 10°. The first extension direction of the first liquid crystal cell forms an angle of 0° to 10° with respect to the first extension direction of the second liquid crystal cell, and forms an angle of 80° to 90° with respect to the first extension directions of the third and fourth liquid crystal cells.

[0010] One embodiment of the present invention is an optical element, comprising a first liquid crystal unit, a second liquid crystal unit, a third liquid crystal unit, and a fourth liquid crystal unit, which are sequentially arranged in an overlapping manner. The first liquid crystal unit, the second liquid crystal unit, the third liquid crystal unit, and the fourth liquid crystal unit each have: a plurality of first electrodes arranged in a stripe shape and extending along a first extension direction; a first orientation film on the plurality of first electrodes; a liquid crystal layer on the first orientation film; a second orientation film on the liquid crystal layer; and a plurality of second electrodes located on the second orientation film, arranged in a stripe shape and extending along a second extension direction intersecting the first extension direction. In each of the first liquid crystal unit, the second liquid crystal unit, the third liquid crystal unit, and the fourth liquid crystal unit, the first orientation film and the second orientation film are configured to align liquid crystal molecules contained in the liquid crystal layer in first orientation directions and second orientation directions intersecting each other, respectively, when no voltage is applied to the plurality of first electrodes and the plurality of second electrodes. In at least one of the first liquid crystal unit, the second liquid crystal unit, the third liquid crystal unit, and the fourth liquid crystal unit, the angle between the first extension direction and the first orientation direction is within 10°, and the angle between the second extension direction and the second orientation direction is within 10°. In liquid crystal cells other than the at least one liquid crystal cell, an angle between the first stretching direction and the first alignment direction is greater than 80° and less than 90°, and an angle between the second stretching direction and the second alignment direction is greater than 80° and less than 90°. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 It is a schematic exploded perspective view of a lighting device according to an embodiment of the present invention.

[0012] Figure 2A It is a schematic plan view of an optical element according to an embodiment of the present invention.

[0013] Figure 2B It is a schematic plan view of an optical element according to an embodiment of the present invention.

[0014] Figure 3A It is a schematic end view of an optical element according to an embodiment of the present invention.

[0015] Figure 3B It is a schematic end view of an optical element according to an embodiment of the present invention.

[0016] Figure 4 It is a partial schematic perspective view of an optical element according to an embodiment of the present invention.

[0017] Figure 5A It is a partial schematic plan view of an optical element according to an embodiment of the present invention.

[0018] Figure 5B It is a partial schematic plan view of an optical element according to an embodiment of the present invention.

[0019] Figure 5C It is a partial schematic plan view of an optical element according to an embodiment of the present invention.

[0020] Figure 6 It is a partial schematic plan view of an optical element according to an embodiment of the present invention.

[0021] Figure 7 It is a schematic end view of an optical element according to an embodiment of the present invention.

[0022] Fig. 8A It is a schematic end view for explaining the operation of the optical element according to the embodiment of the present invention.

[0023] Figure 8B It is a schematic end view for explaining the operation of the optical element according to the embodiment of the present invention.

[0024] Fig.9A It is a schematic end view for explaining the operation of the optical element according to the embodiment of the present invention.

[0025] Fig. 9B It is a schematic end view for explaining the operation of the optical element according to the embodiment of the present invention.

[0026] Fig.10It is a schematic diagram for explaining the operation of the optical element according to the embodiment of the present invention.

[0027] Fig.11 It is a schematic diagram for explaining the operation of the optical element according to the embodiment of the present invention.

[0028] Fig.12 It is a partial schematic perspective view of an optical element according to an embodiment of the present invention.

[0029] Fig.13A It is a schematic end view for explaining the operation of the optical element according to the embodiment of the present invention.

[0030] Fig. 13B It is a schematic end view for explaining the operation of the optical element according to the embodiment of the present invention.

[0031] Fig.14 It is a schematic end view of an optical element according to an embodiment of the present invention.

[0032] Fig.15 It is a schematic end view of an optical element according to an embodiment of the present invention.

[0033] Fig.16 It is a schematic end view of an optical element according to an embodiment of the present invention.

[0034] Fig.17 It is a schematic end view of an optical element according to an embodiment of the present invention.

[0035] Fig.18 It is a schematic end view of an optical element according to an embodiment of the present invention.

[0036] Fig.19 It is a schematic end view of an optical element according to an embodiment of the present invention. DETAILED DESCRIPTION

[0037] Hereinafter, various embodiments of the present invention will be described with reference to the drawings, etc. However, the present invention can be implemented in various forms within the scope not departing from the gist thereof, and is not to be construed as being limited to the description of the embodiments exemplified below.

[0038] In order to make the description clearer, the drawings sometimes schematically show the width, thickness, shape, etc. of each part compared with the actual form, but this is only an example and does not limit the interpretation of the present invention. In this specification and each drawing, for elements having the same function as the elements described in the drawings that have appeared, the same reference numerals are sometimes marked and repeated descriptions are omitted. This reference numeral is used when multiple identical or similar structures are collectively represented, and a hyphen and a natural number are added after the reference numeral when they are represented separately.

[0039] In the present specification and claims, when expressing a form in which another structure is arranged on a certain structure, when it is simply expressed as "on", unless otherwise specified, it includes both a case in which the other structure is arranged directly above the certain structure in a manner connected to the certain structure and a case in which the other structure is arranged above the certain structure with another structure further between them.

[0040] In this specification and claims, the expression "a certain structure is exposed from another structure" means a state where a part of a certain structure is not covered by another structure, and also includes a state where the part not covered by another structure is further covered by another structure. In addition, the state represented by this expression also includes a state where a certain structure is not in contact with another structure.

[0041] <First Embodiment>

[0042] In this embodiment, a lighting device 100 including an optical element 110 as one embodiment of the present invention is described.

[0043] 1. Overall structure

[0044] Figure 1 1 is a schematic expanded perspective view of the lighting device 100. Figure 1 As shown, as a basic structure, the lighting device 100 includes a light source 102 and an optical element 110 overlapping the light source 102. The light source 102 is configured to irradiate light to the optical element 110, and includes one or more light-emitting elements not shown. As the light-emitting element, an organic or inorganic light-emitting element (LED) can be exemplified. An organic LED is a light-emitting element in which a light-emitting organic compound is sandwiched between a pair of electrodes, and an inorganic LED is a light-emitting element in which an inorganic light-emitting material such as aluminum gallium arsenide, gallium arsenide phosphide, indium gallium nitride, gallium nitride, aluminum gallium nitride, gallium phosphide, etc. is sandwiched between a pair of electrodes. The light source 102 is preferably configured to irradiate collimated light with high directivity to the optical element 110.

[0045] The optical element 110 includes a plurality of liquid crystal cells 120 that overlap with the light source 102 and overlap with each other. There is no limitation on the number of the plurality of liquid crystal cells 120, but preferably, two, four, or more liquid crystal cells 120 are included in one optical element 110. Adjacent liquid crystal cells 120 are arranged in a manner such that the ... Figure 1The optical element 110 is bonded with a light-transmitting adhesive layer not shown in the figure. Each liquid crystal unit 120 is composed of a pair of substrates and structures such as electrodes and liquid crystal layers arranged therebetween, and has the function of diffusing light from the light source 102, as will be described later. In the following, the main surface formed by the substrate is set as the xy plane, and the direction perpendicular to the xy plane is set as the z direction. Therefore, the optical element 110 overlaps with the light source 102 in the z direction, and the plurality of liquid crystal units 120 also overlap with each other in the z direction. In the following description, the first liquid crystal unit 120-1, the second liquid crystal unit 120-2, the third liquid crystal unit 120-3 and the fourth liquid crystal unit 120-4 are sequentially arranged from the light source 102 side.

[0046] 2. Liquid crystal unit

[0047] Figure 2A and Figure 2B 1 is a schematic top view of the liquid crystal unit 120 as viewed from the light source 102 side. Figure 2A In the embodiment, the counter substrate 124 is omitted from the pair of substrates (substrate 122 and counter substrate 124). Figure 2A and Figure 2B The schematic diagrams of the end faces of the dotted lines AA′ and BB′ are respectively Figure 3A and Figure 3B .

[0048] As can be seen from these figures, each liquid crystal unit 120 includes a plurality of first electrodes 130 arranged on a substrate 122, a first orientation film 140 on the plurality of first electrodes 130, a liquid crystal layer 128 on the first orientation film 140, a second orientation film 142 on the liquid crystal layer 128, a plurality of second electrodes 132 on the second orientation film 142, and an opposing substrate 124 on the plurality of second electrodes 132.

[0049] (1) Substrate and Counter Substrate

[0050] The substrate 122 and the counter substrate 124 are bonded to each other via a sealing material 126 that is configured in a frame shape, and function as base materials for supporting the plurality of first electrodes 130 and the plurality of second electrodes 132, respectively, and seal the liquid crystal layer 128. In order to allow the light from the light source 102 to pass through and exhibit a lighting function, the substrate 122 and the counter substrate 124 preferably include a material that exhibits a high transmittance to the light from the light emitting element 114. Therefore, for example, the substrate 122 and the counter substrate 124 are preferably configured in a manner including glass, quartz, or a polymer material such as polyimide, polycarbonate, polyester, or acrylic resin. The substrate 122 and the counter substrate 124 may be configured to have a strength that does not deform due to external forces, or may be configured to deform elastically. As Figure 1As shown, the substrate 122 and the opposing substrate 124 may be bonded together in such a manner that a portion of the principal surface of the substrate 122 is exposed from the opposing substrate 124 toward the light source 102 , and a portion of the principal surface of the opposing substrate 124 is exposed from the substrate 122 toward the side opposite to the light source 102 .

[0051] (2) First electrode and second electrode

[0052] like Figure 3A and Figure 3B As shown, a plurality of first electrodes 130 are provided on the substrate 122 in a manner of being in contact with the substrate 122 or separated by a primer layer not shown. The primer layer can be formed by one or more films containing silicon-containing inorganic compounds such as silicon nitride and silicon oxide. In order to impart higher light transmittance to the liquid crystal unit 120, the first electrode 130 is preferably formed by a conductive oxide such as indium-tin oxide (ITO) and indium-zinc oxide (IZO) that exhibits higher transmittance to visible light. Alternatively, the first electrode 130 may be formed by a mesh-like metal film having a plurality of openings so that light from the light source 102 can pass through. By Figure 2A It can be seen that the plurality of first electrodes 130 extend in the same direction and are arranged in a stripe shape. The length of each first electrode 130 (the length in the extension direction of the first electrode 130) also depends on the size of the optical element 110, and can be selected from a range of 5 cm to 15 cm or 1 cm to 10 cm. The interval between two adjacent first electrodes 130 can be selected from a range of 1 μm to 30 μm or 3 μm to 20 μm.

[0053] Similarly, the plurality of second electrodes 132 are also provided on the counter substrate 124 directly or via the primer layer (in Figure 3A , Figure 3B In order to give the liquid crystal unit 120 a high light transmittance, the second electrode 132 is preferably formed of a conductive oxide such as ITO or IZO that has a high transmittance to visible light, or a mesh-shaped metal film having a plurality of openings. FIG. 2A to FIG. 3B As shown, the plurality of second electrodes 132 also extend in the same direction and are arranged in a stripe shape. The length of each second electrode 132 (the length in the extension direction of the second electrode 132) can be selected from a range of 5 cm to 15 cm or from 1 cm to 10 cm. In addition, the interval between two adjacent second electrodes 132 can be selected from a range of 1 μm to 30 μm or from 3 μm to 20 μm, for example.

[0054] Here, a plurality of first electrodes 130 and second electrodes 132 are arranged in a mutually intersecting manner. The extension direction of the first electrode 130 and the extension direction of the second electrode 132 may be perpendicular to each other, but preferably these directions are not completely perpendicular. For example, the angle formed by the extension direction of the first electrode 130 and the extension direction of the second electrode 132 may also be set within a range of greater than 80° and less than 90°. In this way, by making the extension direction of the second electrode 132 and the extension direction of the first electrode 130 deviate from the vertical, the interference of light caused by the first electrode 130 and the second electrode 132 can be suppressed, and the undesirable situation of unexpected coloring or spots in the light from the light source 102 can be prevented.

[0055] A pulsed AC voltage (AC rectangular wave) is applied to the plurality of first electrodes 130. The AC voltage is applied in a manner that the phase is reversed between two adjacent first electrodes 130. Similarly, a pulsed AC voltage is applied to the plurality of second electrodes 132 in a manner that the phase is reversed between two adjacent second electrodes 132. In addition, the first electrodes 130 and the second electrodes 132 are configured in a manner that the first electrodes 130 and the second electrodes 132 are independently driven. Therefore, an AC voltage can be applied only to the first electrode 130 without applying a voltage to the second electrode 132, or a certain voltage can be applied, or vice versa.

[0056] like Figure 3A As shown, every other first electrode 130 selected from the plurality of first electrodes 130 is connected to the first wiring 134-1, and the remaining first electrodes 130 are also connected to the second wiring 134-2 different from the first wiring 134-1 (see Figure 2A ). The first wiring 134-1 and the second wiring 134-2 are exposed from the opposing substrate 124 on the substrate 122 to form terminals 136-1 and 136-2, respectively. An AC voltage is applied from an external circuit (not shown) via these terminals 136-1 and 136-2. Similarly, every other second electrode 132 selected from the plurality of second electrodes 132 is connected to the third wiring 134-3, and the remaining second electrodes 132 are connected to a fourth wiring 134-4 different from the third wiring 134-3 ( Figure 3B ). The third wiring 134-3 and the fourth wiring 134-4 are exposed from the substrate 122 on the counter substrate 124 to form terminals 136-3 and 136-4, respectively, and an AC voltage is applied from an external circuit (not shown) via these terminals 136-3 and 136-4. With such a structure, the plurality of first electrodes 130 on the substrate 122 side and the plurality of second electrodes 132 on the counter substrate 124 side can be driven independently. Furthermore, the first liquid crystal unit 120-1 to the fourth liquid crystal unit 120-4 can also be driven independently.

[0057] (3) Liquid crystal layer, first alignment film, and second alignment film

[0058] The liquid crystal layer 128 includes liquid crystal molecules. The structure of the liquid crystal molecules is not limited. Therefore, the liquid crystal molecules may be nematic liquid crystals or smectic liquid crystals. As liquid crystal molecules, positive liquid crystals whose dielectric constant in the long axis direction is greater than the dielectric constant in the direction perpendicular to the long axis are used. The liquid crystal layer 128 is sealed in a space formed by the substrate 122, the counter substrate 124, and the sealing material 126 in a manner sandwiched by the first orientation film 140 and the second orientation film 142.

[0059] The thickness of the liquid crystal layer 128, that is, the distance between the first orientation film 140 and the second orientation film 142, is also arbitrary, but is preferably larger than the spacing between the first electrode 130 and the second electrode 132. For example, the thickness of the liquid crystal layer 128 is preferably set to be more than 2 times and less than 10 times, more than 2 times and less than 5 times, or more than 2 times and less than 3 times the spacing between the first electrode 130 or the second electrode 132. The specific thickness of the liquid crystal layer 128 can be selected, for example, from a range of more than 10 μm and less than 60 μm or more than 10 μm and less than 50 μm. Although not shown in the figure, a spacer for maintaining the thickness throughout the entirety of each liquid crystal unit 120 may also be provided in the liquid crystal layer 128. In addition, when the above-mentioned thickness of the liquid crystal layer 128 is used in a liquid crystal display device, the high responsiveness required for displaying dynamic images cannot be obtained, and it is difficult to exhibit the function as a liquid crystal display device.

[0060] The first orientation film 140 and the second orientation film 142 contain polymers such as polyimide and polyester, and sandwich the liquid crystal layer 128. The first orientation film 140 is configured to align the liquid crystal molecules contained in the liquid crystal layer 128 in a certain direction when no potential difference is generated between the adjacent first electrodes 130. Similarly, the second orientation film 142 is also configured to align the liquid crystal molecules contained in the liquid crystal layer 128 in a certain direction when no potential difference is generated between the adjacent second electrodes 132. Hereinafter, the direction in which the first orientation film 140 and the second orientation film 142 align the liquid crystal molecules in the absence of an electric field is referred to as the orientation direction. The orientation direction can be given, for example, by rubbing treatment. Alternatively, the orientation direction can also be given to the first orientation film 140 and the second orientation film 142 by photo-orientation. Photo-orientation is an orientation treatment without friction using light, for example, irradiating an orientation film that has not been rubbed with polarized light in the ultraviolet region from a specified direction. As a result, a photoreaction occurs in the orientation film, anisotropy is introduced into the surface of the orientation film, and the liquid crystal orientation control capability is given.

[0061] Here, if Figure 4As shown, the first alignment film 140 and the second alignment film 142 are configured such that their alignment directions are orthogonal to each other, or the angle between them is greater than 80° and less than 90° (see Figure 4 The hollow arrows 144, 146 in FIG.

[0062] On the other hand, the plurality of first electrodes 130 and the first alignment film 140 may be formed as follows. Figure 5A As shown, the extending direction of the plurality of first electrodes 130 is arranged parallel to the orientation direction of the first orientation film 140 (see hollow arrow 144), or as shown in FIG. Figure 5B As shown, the extension direction of the plurality of first electrodes 130 is configured to be inclined from the orientation direction of the first orientation film 140. In the latter case, the angle formed by the extension direction of the plurality of first electrodes 130 and the orientation direction of the first orientation film 140 can be selected from a range of greater than 0° and less than 10°, greater than 1° and less than 5°, or greater than 1° and less than 3°. By making the extension direction of the plurality of first electrodes 130 inclined from the orientation direction of the first orientation film 140, the direction in which the liquid crystal molecules are twisted can be fixed when a lateral electric field is generated, thereby improving the responsiveness of the liquid crystal molecules and preventing the refractive index distribution of the liquid crystal layer 128 from being disturbed by the deviation of the rotation direction of the liquid crystal molecules.

[0063] Although not shown, the relationship between the plurality of second electrodes 132 and the second orientation film 142 is the same. That is, the plurality of second electrodes 132 and the second orientation film 142 can be configured so that the extension direction of the plurality of second electrodes 132 is parallel to the orientation direction of the second orientation film 142, or can be configured so that the extension direction of the plurality of second electrodes 132 is inclined from the orientation direction of the second orientation film 142 within a range of greater than 0° and less than 10°, greater than 1° and less than 5°, or greater than 1° and less than 3°. As described above, by utilizing the inclination between the extension direction of the plurality of second electrodes 132 and the orientation direction of the second orientation film 142, the responsiveness of the liquid crystal molecules is improved, and the refractive index distribution of the liquid crystal layer 128 can be precisely controlled. In addition, in this way, when the angle between the extension direction of the electrode and the orientation direction of the orientation film covering the electrode is 0° to less than 10°, it can be said that "the extension direction of the electrode is consistent with the orientation direction of the orientation film".

[0064] Here, when the first electrode 130 has a straight line shape as a whole, the extending direction of each first electrode 130 is the direction from the intersection with the first wiring or the second wiring to the front end of the first electrode 130. Figure 5CAs shown, each first electrode 130 can have a curved structure including a plurality of straight line portions. In this case, the plurality of first electrodes 130 are arranged in a manner that the extension direction of at least one straight line portion is inclined from the orientation direction of the first orientation film 140 within a range of greater than 0° and less than 10°, greater than 1° and less than 5°, or greater than 1° and less than 3°. The same is true for the second electrode 132. That is, in the case where the second electrode 132 has a straight line shape as a whole, the extension direction of each second electrode 132 is a direction from the intersection with the third wiring or the fourth wiring to the front end of the second electrode 132. Although not shown, each second electrode 132 can also have a curved structure including a plurality of straight line portions. In this case, the plurality of second electrodes 132 are arranged in a manner that the extension direction of at least one straight line portion is inclined from the orientation direction of the second orientation film 142 within a range of greater than 0° and less than 10°, greater than 1° and less than 5°, or greater than 1° and less than 3°. Thus, by forming one or more straight line portions inclined from the alignment direction of the first alignment film 140 or the second alignment film 142 in each of the first electrodes 130 and the second electrodes 132 , the rotation direction of the liquid crystal molecules can be restricted and the refractive index distribution can be precisely controlled.

[0065] In addition, in order to more precisely restrict the rotation direction of the liquid crystal molecules in each liquid crystal unit 120, it is preferred to have a straight edge ( Figure 6 In other words, it is preferred that all or at least one of the first electrodes 130 be configured so that the front end has an acute angle. By configuring each first electrode 130 in this way, when a potential difference is applied between adjacent first electrodes 130, it is possible to avoid that the direction of the lateral electric field at the front end is perpendicular to the orientation direction of the first orientation film 140, thereby limiting the rotation direction of the liquid crystal. The same is true for the second electrode 132.

[0066] 3. Configuration of multiple liquid crystal cells in an optical element

[0067] use Figure 7The configuration of the first liquid crystal unit 120-1 to the fourth liquid crystal unit 120-4 in this embodiment is described with reference to a schematic end view. In the following description, the extending directions of the first electrode 130 and the second electrode 132, and the alignment directions of the first orientation film 140 and the second orientation film 142 are described using the x direction and the y direction which are orthogonal to each other, but as described above, in each liquid crystal unit 120, the extending direction of the first electrode 130 and the alignment direction of the first orientation film 140 may be parallel or may be inclined to each other. Similarly, in each liquid crystal unit 120, the extending direction of the second electrode 132 and the alignment direction of the second orientation film 142 may be parallel or may be inclined to each other. Furthermore, in each liquid crystal unit 120, the alignment directions of the first orientation film 140 and the second orientation film 142 may be orthogonal or may cross in a manner deviating from the vertical. Therefore, when a direction is indicated in the following description, it includes not only directions parallel to the direction, but also directions inclined within a range of greater than 0° and less than 10°, greater than 1° and less than 5°, or greater than 1° and less than 3°. In addition, a direction orthogonal to a direction includes not only directions perpendicular to the direction, but also directions intersecting at an angle of greater than 80° and less than 90°, greater than 85° and less than 89°, or greater than 87° and less than 89°. Similarly, a direction parallel to a direction includes not only directions parallel to the direction, but also directions inclined from the direction at an angle of greater than 0° and less than 10°, greater than 1° and less than 5°, or greater than 1° and less than 3°.

[0068] like Figure 7 As shown, in the optical element 110 , the first to fourth liquid crystal cells 120 - 1 to 120 - 4 having the same structure are arranged to overlap each other, and the adjacent liquid crystal cells 120 are bonded by an adhesive layer 160 that allows visible light to pass.

[0069] The first liquid crystal unit 120-1 and the second liquid crystal unit 120-2 adopt the same configuration. Specifically, the first liquid crystal unit 120-1 and the second liquid crystal unit 120-2 are both configured such that the plurality of first electrodes 130 extend in one direction (here, the y direction), and the plurality of second electrodes 132 extend in a direction intersecting the direction (here, the x direction). Therefore, in each of the first liquid crystal unit 120-1 and the second liquid crystal unit 120-2, the orientation directions of the first orientation film 140 and the second orientation film 142 are the y direction and the x direction, respectively. In other words, in each of the first liquid crystal unit 120-1 and the second liquid crystal unit 120-2, the extension directions of the plurality of first electrodes 130 and the plurality of second electrodes 132 are orthogonal to each other and are parallel to the orientation directions of the first orientation film 140 and the second orientation film 142, respectively.

[0070] On the other hand, the third liquid crystal unit 120-3 and the fourth liquid crystal unit 120-4 adopt the same configuration as each other, but adopt a configuration different from the first liquid crystal unit 120-1 or the second liquid crystal unit 120-2. Specifically, the third liquid crystal unit 120-3 and the fourth liquid crystal unit 120-4 are both configured so that the plurality of first electrodes 130 extend along the x direction and the plurality of second electrodes 132 extend along the y direction. Therefore, in each of the third liquid crystal unit 120-3 and the fourth liquid crystal unit 120-4, the orientation directions of the first orientation film 140 and the second orientation film 142 are respectively in the x direction and the y direction. In each of the third liquid crystal unit 120-3 and the fourth liquid crystal unit 120-4, the extension directions of the plurality of first electrodes 130 and the plurality of second electrodes 132 are also orthogonal to each other and are parallel to the orientation directions of the first orientation film 140 and the second orientation film 142, respectively.

[0071] In addition, the extension direction of the first electrode 130 of the first liquid crystal unit 120-1 may be completely parallel to the extension direction of the first electrode 130 of the second liquid crystal unit 120-2, but the angle formed by these directions may be greater than 0° and less than 10°, greater than 1° and less than 5°, or greater than 1° and less than 3°. Similarly, the extension direction of the second electrode 132 of the first liquid crystal unit 120-1 may be completely parallel to the extension direction of the second electrode 132 of the second liquid crystal unit 120-2, but the angle formed by these directions may be greater than 0° and less than 10°, greater than 1° and less than 5°, or greater than 1° and less than 3°. Furthermore, the extension direction of the second electrode 132 of the first liquid crystal unit 120-1 may be completely perpendicular to the extension direction of the first electrode 130 of the second liquid crystal unit 120-2, but the angle formed by these directions may be greater than 80° and less than 90°, greater than 85° and less than 89°, or greater than 87° and less than 89°. Similarly, the extension direction of the first electrode 130 of the first liquid crystal unit 120-1 can be completely perpendicular to the extension direction of the second electrode 132 of the second liquid crystal unit 120-2, but the angle formed by these directions can also be greater than 80° and less than 90°, greater than 85° and less than 89°, or greater than 87° and less than 89°. Therefore, between the first liquid crystal unit 120-1 and the second liquid crystal unit 120-2, the extension directions of the first electrode 130 and the second electrode 132 can also deviate from each other in the xy plane. By forming such a deviation, it is possible to suppress the interference of light and prevent the occurrence of uneven illumination. The same relationship can also be constructed in the extension directions of the first electrode 130 and the second electrode 132 between the second liquid crystal unit 120-2 and the third liquid crystal unit 120-3, and between the third liquid crystal unit 120-3 and the fourth liquid crystal unit 120-4.

[0072] 4. Light distribution control based on optical elements

[0073] (1) Diffusion of light in each liquid crystal cell

[0074] The optical element 110 diffuses the light emitted from the light source 102 in a certain direction. Therefore, by driving the plurality of liquid crystal cells 120 individually, the light from the light source 102 is changed into an arbitrary shape, and as a result, the light distribution of the lighting device 100 can be controlled to arbitrarily control the shape of the region (hereinafter, the irradiation region) of the object irradiated by the lighting device 100. Here, the principle of diffusion of light in one liquid crystal cell 120 is described.

[0075] [1] When not driving

[0076] Fig. 8A and Figure 8B A schematic end view showing a non-driven state of one liquid crystal cell 120 . Fig. 8A is a schematic end view viewed from the y direction, Figure 8B : is a schematic end view viewed from the x direction. In the following figures, liquid crystal molecules are represented by hollow ovals or circles.

[0077] The case where the liquid crystal unit 120 is not driven refers to the case where no voltage is applied to the plurality of first electrodes 130 and the plurality of second electrodes 132, or a certain voltage is applied to them. In this case, no transverse electric field is generated between the plurality of first electrodes 130 and the plurality of second electrodes 132. When not driven, since there is no electric field, the liquid crystal molecules are oriented in the orientation direction of the first orientation film 140 and the second orientation film 142. Therefore, the liquid crystal molecules are oriented along the orientation direction of the first orientation film 140 (here, the y direction) near the substrate 122, and as they approach the opposing substrate 124, they rotate and twist 90° with the z direction as the central axis. As a result, when the light emitted from the light source 102 passes through the liquid crystal layer from one substrate to another, although the polarization component rotates along the twisted state of the liquid crystal molecules (this phenomenon is called optical rotation), since the liquid crystal molecules do not produce a refractive index distribution, no diffusion phenomenon or the like occurs. As a result, the shape of the light emitted from the light source 102 is reflected in the shape of the irradiated area. In addition, when the light source 102 emits collimated light with high directivity, a narrow area can be selectively irradiated.

[0078] [2] When driving

[0079] One form of driving the liquid crystal unit 120 is to apply a pulsed AC voltage to the plurality of first electrodes 130 and the plurality of second electrodes 132 in a manner that the phases are reversed between the adjacent first electrodes 130 and the second electrodes 132. The frequency of the AC voltage is the same in each liquid crystal unit 120. The AC voltage can be selected, for example, from a range of 3V to 50V or 3V to 30V. The directions in which the first electrodes 130 and the second electrodes 132 extend are orthogonal or cross in a range of 80° to less than 90°, 85° to 89°, or 87° to 89°. Therefore, by applying the AC voltage, a transverse electric field that is orthogonal to each other or crosses in a range of 80° to less than 90° is generated between the adjacent first electrodes 130 and the adjacent second electrodes 132. An electric field (longitudinal electric field) is also generated between the first electrode 130 and the second electrode 132, but the thickness of the liquid crystal layer 128 is larger than the intervals between the adjacent first electrodes 130 and the second electrodes 132. Therefore, the longitudinal electric field is significantly smaller than the transverse electric field and can be ignored, so each liquid crystal molecule is aligned according to the transverse electric field.

[0080] When a transverse electric field is generated in the liquid crystal layer 128, the liquid crystal molecules on the first electrode 130 side are oriented in the direction of the transverse electric field, while being convexly curved between adjacent first electrodes 130 ( Fig.9A ) orientation. The same is true on the second electrode 132 side. The liquid crystal molecules are oriented in the direction of the lateral electric field while being convexly oriented in a downward arc shape ( Fig. 9B ) orientation. Such a change in the orientation of the liquid crystal molecules generates a refractive index distribution in the liquid crystal layer 128. As a result, Fig.10As shown, the component (polarization component) 152 parallel to the lateral electric field formed by the second electrode 132 in the light incident from the opposing substrate 124 of the liquid crystal unit 120 to the liquid crystal layer 128 is diffused, and the other polarization components 154 are transmitted. Here, by driving the liquid crystal unit 120, an electric field is formed between the adjacent first electrodes 130 and an electric field is formed between the adjacent second electrodes 132, and the liquid crystal molecules near each substrate rotate in a manner along the direction of the electric field (for example, in a direction orthogonal to the orientation direction when not driven). As a result, the orientation state achieved when not driven, that is, the twisted state in which the orientation of the liquid crystal molecules gradually rotates from the substrate 122 toward the opposing substrate 124 when observed from the z direction, is destroyed, and the two polarization components 152 and 154 will not be optically rotated even if they pass through the liquid crystal layer 128. Therefore, the polarization components 152 and 154 maintain the polarization direction before and after passing through the first liquid crystal unit 120-1, while being affected by the refractive index distribution of the liquid crystal molecules oriented in the direction consistent with the orientation of each polarization component. More specifically, the polarization component 152 in the y direction is influenced by the refractive index distribution of the liquid crystal molecules on the opposing substrate 124 side and diffuses in the y direction, but the polarization axis is not changed in the x direction. In addition, the polarization component 154 in the x direction is influenced by the refractive index distribution of the liquid crystal molecules on the substrate 122 side and diffuses in the x direction, but the polarization axis is not changed in the y direction.

[0081] Another form of driving the liquid crystal unit 120 is to apply a pulsed AC voltage to one of the plurality of first electrodes 130 and the plurality of second electrodes 132 without applying a voltage to the other, or to apply a constant voltage. In this case, the AC voltage is applied in a manner that the phase is reversed between adjacent first electrodes 130 or between adjacent second electrodes 132. For example, when a pulsed AC voltage is applied to the plurality of first electrodes 130, on the substrate 122 side, the liquid crystal molecules are oriented in the direction of the lateral electric field while being convexly arc-shaped ( Fig.11 ) orientation, a refractive index distribution is generated in the liquid crystal layer 128. Fig.11As shown, light incident on the liquid crystal layer 128 from the opposing substrate 124 of the liquid crystal unit 120 is not diffused by the liquid crystal layer 128 on the second electrode 132 side. However, according to the refractive index distribution formed in the liquid crystal layer 128 on the first electrode 130 side, the polarization component 154 parallel to the direction of the transverse electric field on the first electrode 130 side is selectively diffused, and the polarization component 152 on the other side is not diffused. At this time, in the liquid crystal layer 128 on the second electrode 132 side, the orientation when not driven is maintained, and the liquid crystal molecules are oriented in the y direction. In addition, on the first electrode 130 side, the liquid crystal molecules are also in an orientation state convex upward along the y direction as the direction of the transverse electric field. As a result, the twisted state of the above-mentioned liquid crystal molecules when not driven is eliminated, and the two polarization components 152 and 154 will not be optically rotated even if they both pass through the liquid crystal layer 128. Therefore, in this method, it is possible to selectively diffuse only the polarization component 154 while maintaining the polarization directions of the two polarization components 152 and 154.

[0082] Detailed description is omitted, and the same is true when no voltage is applied to the plurality of first electrodes 130, or when a pulsed AC voltage is applied to the plurality of second electrodes 132 while a constant voltage is applied. In this case, one component of the incident light (here, the polarization component 152) is selectively diffused by the liquid crystal layer 128 on the second electrode 132 side, and the other polarization component 154 is not diffused. In addition, the two polarization components 152 and 154 are not optically rotated. In this way, the liquid crystal unit 120 can selectively diffuse one polarization component while maintaining the polarization directions of the two polarization components 152 and 154 by forming a transverse electric field in one of the plurality of first electrodes 130 and the plurality of second electrodes 132.

[0083] The effects of the extending direction of the first electrode 130 and the second electrode 132 with respect to the light from the light source 102 incident from the counter substrate 124 side, the alignment direction of the first alignment film 140 and the second alignment film 142, and the presence or absence of driving of the first electrode 130 and the second electrode 132 are summarized in Table 1. As shown in Table 1, by appropriately selecting the configuration of the liquid crystal cell 120 (that is, the extending direction of the first electrode 130 and the second electrode 132, or the alignment direction of the first alignment film 140 and the second alignment film 142) and the presence or absence of driving of the first electrode 130 and the second electrode 132, the two polarization components can be diffused independently, or the two polarization components can be optically rotated simultaneously.

[0084] [Table 1]

[0085]

[0086] (2) Light distribution control based on optical elements

[0087] As described above, the first liquid crystal cell 120-1 to the fourth liquid crystal cell 120-4 can be driven independently, and further, the plurality of first electrodes 130 and the plurality of second electrodes 132 can be driven independently in each liquid crystal cell 120. Therefore, in the optical element 110 involved in this embodiment, by appropriately driving the plurality of first electrodes 130 and the plurality of second electrodes 132 of the first liquid crystal cell 120-1 to the fourth liquid crystal cell 120-4, the light from the light source 102 can be changed into an arbitrary shape.

[0088] For example Figure 7 As shown, it is assumed that the light from the light source 102 is irradiated from the first liquid crystal unit 120-1 side of the optical element 110 and the light is taken out from the fourth liquid crystal unit 120-4. At this time, each liquid crystal unit 120 is driven as shown in Table 2. That is, the first electrode 130 and the second electrode 132 of all liquid crystal units 120 are driven. In this case, as shown in Table 2, the polarization component in the y direction of the incident light is diffused once in the y direction by four liquid crystal units 120, and diffused a total of 4 times. Similarly, the polarization component in the x direction is also diffused a total of 4 times in the x direction. Therefore, the incident light given a circular irradiation area can be changed into light given a cross-shaped irradiation area. In addition, by diffusing each polarization component multiple times (for example, at least 3 times), the split state is dispersed accordingly, so that the coloring of the light can be prevented. In addition, the length of the cross shape in the x direction and the y direction can be adjusted by appropriately adjusting the AC voltage applied to the first electrode 130 and the second electrode 132. In addition, unless otherwise specified, hyphens in Table 2 mean that incident light is transmitted without being diffused or optically rotated (the same applies to the following tables).

[0089] [Table 2]

[0090] Table 2 Behavior of light incident on the optical element 110 (1)

[0091]

[0092] Alternatively, a part of the four liquid crystal cells 120 may be driven. For example, as shown in Table 3, the first electrode 130 and the second electrode 132 of the first liquid crystal cell 120-1, the second liquid crystal cell 120-2, and the fourth liquid crystal cell 120-4 are driven, while the first electrode 130 and the second electrode 132 of the third liquid crystal cell are not driven. In this case, the polarization component in the y direction of the incident light is diffused in the y direction, the y direction, and the x direction by the first liquid crystal cell 120-1, the second liquid crystal cell 120-2, and the fourth liquid crystal cell 120-4, respectively, and the polarization component in the x direction of the incident light is diffused in the x direction, the x direction, and the y direction by the first liquid crystal cell 120-1, the second liquid crystal cell 120-2, and the fourth liquid crystal cell 120-4, respectively. As a result, the irradiation area can be greatly expanded while maintaining the shape of the irradiation area of ​​the light source 102. In addition, by diffusing each polarization component multiple times (for example, more than 3 times), coloring of light can be prevented.

[0093] [Table 3]

[0094] Table 3 Behavior of light incident on the optical element 110 (2)

[0095]

[0096] a 90° optical rotation using the third liquid crystal unit

[0097] Alternatively, a part of the four liquid crystal cells 120 may be driven as shown in Table 4. In this example, the second electrodes 132 of the first liquid crystal cell 120-1 and the second liquid crystal cell 120-2 and the first electrode 130 of the fourth liquid crystal cell 120-4 are driven. In this case, the polarization component in the y direction of the incident light is diffused in the y direction by the first liquid crystal cell 120-1 and the second liquid crystal cell 120-2, and the polarization component in the x direction of the incident light is diffused in the y direction by the fourth liquid crystal cell 120-4. As a result, the incident light that is provided with a circular irradiation area can be changed into light that is provided with a linear irradiation area extending in the y direction.

[0098] [Table 4]

[0099] Table 4 Behavior of light incident on the optical element 110 (3)

[0100]

[0101] a 90° optical rotation using the third liquid crystal unit

[0102] Alternatively, a part of the four liquid crystal cells 120 may be driven as shown in Table 5. In this example, the first electrodes 130 of the first liquid crystal cell 120-1 and the second liquid crystal cell 120-2 and the second electrode 132 of the fourth liquid crystal cell 120-4 are driven. In this case, the polarization component in the y direction of the incident light is optically rotated by the third liquid crystal cell 120-3 to become the x polarization component, and then diffused in the x direction by the fourth liquid crystal cell 120-4. On the other hand, the polarization component in the x direction of the incident light is diffused in the x direction by the first liquid crystal cell 120-1 and the second liquid crystal cell 120-2, and then optically rotated by the third liquid crystal cell 120-3 to give the polarization component in the y direction. As a result, the incident light that gives a circular irradiation area can be changed into light that gives a linear irradiation area extending in the x direction.

[0103] [Table 5]

[0104] Table 5 Behavior of light incident on the optical element 110 (4)

[0105]

[0106] 2 90° optical rotation using the third liquid crystal unit

[0107] As described above, in the lighting device 100 according to the present embodiment, the light incident from the light source 102 can be changed into light having an irradiation area of ​​an arbitrary shape by using the optical element 110. In addition, each polarization component of the incident light can be diffused multiple times (for example, three times or more), so that the coloring of the light whose light distribution has been changed can be prevented, and the color of the light from the light source 102 can be reproduced. In this way, in the lighting device 100, a high degree of light distribution control can be achieved without coloring the light.

[0108] <Second Embodiment>

[0109] In this embodiment, an optical element 112 having a structure different from that of the optical element 110 will be described. The description of the same or similar structure as that described in the first embodiment may be omitted.

[0110] 1. Optical component structure and light distribution control

[0111] As described in the first embodiment, the first liquid crystal unit 120-1 to the fourth liquid crystal unit 120-4 included in the optical element 110 have the same structure. In addition, in each liquid crystal unit 120, the extension direction of the plurality of first electrodes 130 is parallel to the orientation direction of the first orientation film 140 or forms an angle of not less than 0° and not more than 10°, and the extension direction of the plurality of second electrodes 132 is also parallel to the orientation direction of the second orientation film 142 or forms an angle of not less than 0° and not more than 10°.

[0112] On the other hand, at least one of the first liquid crystal cell 120-1 to the fourth liquid crystal cell 120-4 included in the optical element 112 has the same structure as the liquid crystal cell 120 described in the first embodiment, but the others have different structures. As described later, in the liquid crystal cell with a different structure, both polarization components of the incident light are optically rotated regardless of whether the optical element 112 is driven. Therefore, the liquid crystal cell with a different structure is also referred to as an optically active liquid crystal cell.

[0113] More specifically, if Fig.12 As shown, in the optically active liquid crystal unit 121, the extension direction of the plurality of first electrodes 130 and the orientation direction of the first orientation film 140 are perpendicular to each other or form an angle of 80° or more and 90° or less, and the extension direction of the plurality of second electrodes 132 and the orientation direction of the second orientation film 142 are also perpendicular to each other or form an angle of 80° or more and 90° or less (see Fig.12 148, 150 in the figure). As in the liquid crystal cell 120, in the optically active liquid crystal cell 121, the extension direction of the first electrode 130 and the extension direction of the second electrode 132 are perpendicular to each other or form an angle of 80° or more and 90° or less, and the orientation films of the first orientation film 140 and the second orientation film 142 are also perpendicular to each other or form an angle of 80° or more and 90° or less. In addition, in this way, when the angle between the extension direction of the electrode and the orientation direction of the orientation film covering the electrode is greater than 10°, and more preferably, the angle between them is 80° to 90°, it can be said that "the extension direction of the electrode intersects the orientation direction of the orientation film".

[0114] In the optically active liquid crystal unit 121, when not driven, Fig.13A As shown, the liquid crystal molecules are oriented according to the orientation directions of the first orientation film 140 and the second orientation film 142. Therefore, the orientation direction of the liquid crystal molecules becomes the orientation direction of the first orientation film 140 (here, the x direction) near the substrate 122, and rotates with the z direction as the center axis as it approaches the opposing substrate 124, twisting the difference in the orientation directions between these orientation films (for example, if the orientation directions of the two orientation films are orthogonal, then twisting 90°). As a result, the light emitted from the light source 102 does not diffuse when the liquid crystal unit 120 is not driven, but stays in the optical rotation, so the shape of the light emitted from the light source 102 is reflected in the shape of the irradiated area. In addition, when the light source 102 emits collimated light with high directivity, a narrower area can be selectively irradiated.

[0115] On the other hand, for example, when an AC voltage is applied to the plurality of first electrodes 130 and the plurality of second electrodes 132 to drive the optically active liquid crystal cell 121, similarly to the liquid crystal cell 120, the liquid crystal molecules on the first electrode 130 side and the second electrode 132 side are oriented in the direction of the lateral electric field, while being convex upward and convex downward between the first electrodes 130 and the second electrode 132, respectively. Fig. 13B ) orientation. However, at this time, the liquid crystal molecules hardly rotate in the xy plane, so the orientation direction in the xy plane does not change. Therefore, the twist of the liquid crystal molecules with the z direction as the center axis is maintained. Therefore, the polarization component parallel to the lateral electric field formed by the second electrode 132 in the light incident from the opposing substrate 124 of the liquid crystal unit 120 to the liquid crystal layer 128 diffuses in the liquid crystal layer 128 on the second electrode 132 side, and then is optically rotated in the liquid crystal layer 128, and then diffuses in the liquid crystal layer 128 on the first electrode 130 side. In this way, in the optically rotating liquid crystal unit 121, optical rotation is generated simultaneously with diffusion during driving. In addition, similarly to the liquid crystal unit 120, by applying an AC voltage to only one of the first electrode 130 and the second electrode 132, it is also possible to selectively diffuse only one polarization component in one direction. In addition, even when an AC voltage is applied to only one of the first electrode 130 and the second electrode 132, the twist of the liquid crystal molecules with the z direction as the center axis can be maintained, so that the two polarization components are optically rotated.

[0116] The number of liquid crystal cells 120 included in the optical element 112 is not limited. Fig.14 As shown, the third liquid crystal cell 120-3 may also be the optically active liquid crystal cell 121, and the others may also be the liquid crystal cells 120. In this case, the first liquid crystal cells 120-1 to the fourth liquid crystal cells 120-4 may be arranged in such a manner that the extension direction of the first electrode 130 of the first liquid crystal cell 120-1 is at an angle of 0° or more and 10° or less relative to the extension direction of the first electrode 130 of the second liquid crystal cell 120-2, and at an angle of 80° or more and 90° or less relative to the extension direction of the first electrode 130 of the third liquid crystal cell 120-3 and the fourth liquid crystal cell 120-4. In addition, the present invention is not limited to the third liquid crystal cell, and any one or two of the first liquid crystal cell 120-1, the second liquid crystal cell 120-2, and the fourth liquid crystal cell 120-4 may be used as optically active liquid crystal cells.

[0117] The driving method of the optical element 112 may be appropriately determined, and the light from the light source 102 can be changed into various shapes by selecting the driving method. For example, the light from the light source 102 is incident on the optical element 112 from the first liquid crystal cell 120-1 side, and the optical element 112 is driven as shown in Table 6. That is, the first electrode 130 and the second electrode 132 of the first liquid crystal cell 120-1 and the second liquid crystal cell 120-2, and the second electrode 132 of the third liquid crystal cell 120-3 as the optically active liquid crystal cell 121 are driven. In this case, the polarization component in the y direction of the incident light is diffused in the y direction without being optically rotated by the first liquid crystal cell 120-1 and the second liquid crystal cell 120-2, and then is optically rotated twice by the third liquid crystal cell 120-3 and the fourth liquid crystal cell 120-4 functioning as the optically active liquid crystal cell 121, thereby returning to the polarization component in the y direction. On the other hand, the polarization component in the x direction is diffused three times in total in the x direction by the first liquid crystal cell 120-1, the second liquid crystal cell 120-2, and the third liquid crystal cell 120-3 functioning as the optically rotatable liquid crystal cell 121, and is optically rotated twice by the third liquid crystal cell 120-3 and the fourth liquid crystal cell 120-4 to restore the polarization component in the x direction. In this way, the polarization components in the x direction and the y direction can be diffused multiple times in the x direction and the y direction, respectively, so that the incident light that is given a circular irradiation area can be changed into light that is given a cross-shaped irradiation area. In addition, since any polarization component is diffused multiple times (the polarization component in the x direction is at least three times), the coloring of light can also be effectively suppressed.

[0118] [Table 6]

[0119] Table 6 Behavior of light incident on the optical element 112 (1)

[0120]

[0121] a 90° optical rotation using the third liquid crystal unit

[0122] b 90° optical rotation using the fourth liquid crystal unit

[0123] Alternatively, as shown in Table 7, all four liquid crystal cells 120 may be driven. That is, the first electrodes 130 and the second electrodes 132 of all liquid crystal cells 120 including the third liquid crystal cell 120-3 functioning as the optically active liquid crystal cell 121 may be driven. By such driving, the polarization component in the y direction of the incident light is diffused in the y direction, the y direction, and the x direction by the first liquid crystal cell 120-1, the second liquid crystal cell 120-2, and the fourth liquid crystal cell 120-4 respectively without being optically active, and is optically active by the third liquid crystal cell 120-3 (that is, the optically active liquid crystal cell 121) to become the polarization component in the x direction. On the other hand, the polarization component in the x direction is diffused in the x direction by the first liquid crystal cell 120-1, the second liquid crystal cell 120-2, and the third liquid crystal cell 120-3, and is optically active by the third liquid crystal cell 120-3, and is diffused in the y direction by the third liquid crystal cell 120-3 and the fourth liquid crystal cell 120-4. As a result, incident light can be diffused in the x-direction and the y-direction while maintaining a circular irradiation area. In addition, any polarization component is diffused multiple times (at least three times), so coloring of light can also be effectively suppressed.

[0124] [Table 7]

[0125] Table 7 Behavior of light incident on the optical element 112 (2)

[0126]

[0127] a Optical rotation using the third liquid crystal unit

[0128] Alternatively, the optical element 112 may be driven as shown in Table 8. That is, the second electrodes 132 of the first liquid crystal cell 120-1 and the second liquid crystal cell 120-2 may be driven, and the first electrodes 130 of the third liquid crystal cell 120-3 and the fourth liquid crystal cell 120-4 may be driven. In this case, the polarization component in the y direction of the incident light is diffused in the y direction without being optically rotated by the first liquid crystal cell 120-1 and the second liquid crystal cell 120-2, and is optically rotated by the third liquid crystal cell 120-3 (i.e., the optically rotating liquid crystal cell 121) to become the polarization component in the x direction. On the other hand, the polarization component in the x direction is diffused in the y direction by the third liquid crystal cell 120-3 and the fourth liquid crystal cell 120-4, and is optically rotated by the third liquid crystal cell 120-3 to become the polarization component in the y direction. As a result, the incident light that is provided with a circular irradiation area can be changed into light that is provided with a linear irradiation area extending in the y direction.

[0129] [Table 8]

[0130] Table 8 Action of light incident on the optical element 112 (3)

[0131]

[0132] a Optical rotation using the third liquid crystal unit

[0133] Alternatively, the optical element 112 may be driven as shown in Table 9. That is, the first electrodes 130 of the first liquid crystal unit 120-1 and the second liquid crystal unit 120-2 may be driven, and the second electrodes 132 of the third liquid crystal unit 120-3 and the fourth liquid crystal unit 120-4 may be driven. In this case, the polarization component in the y direction of the incident light is diffused in the x direction without being optically rotated by the fourth liquid crystal unit 120-4, and is optically rotated by the third liquid crystal unit 120-3 (i.e., the optically rotating liquid crystal unit 121) to become the polarization component in the x direction. On the other hand, the polarization component in the x direction is diffused in the x direction by the first liquid crystal unit 120-1 and the second liquid crystal unit 120-2, and is diffused in the x direction and optically rotated by the third liquid crystal unit 120-3 to change into the light of the y component. As a result, the incident light that is given a circular irradiation area can be changed into the light that is given a linear irradiation area extending in the x direction. In addition, at least one of the polarization components (the polarization component in the x direction) is also diffused multiple times (at least 3 times), so the coloring of the light can also be effectively suppressed.

[0134] [Table 9]

[0135] Table 9 Behavior of light incident on the optical element 112 (4)

[0136]

[0137] a Optical rotation using the third liquid crystal unit

[0138] 2. Modification 1

[0139] The optical element 112 includes three liquid crystal units 120 and one optically active liquid crystal unit 121, but the structure of the optical element 112 is not limited thereto, and may also include a plurality of optically active liquid crystal units 121. Fig.15As shown, the first liquid crystal cell 120-1 and the second liquid crystal cell 120-2 may also be the optically active liquid crystal cell 121. In this case, the first liquid crystal cell 120-1 to the fourth liquid crystal cell 120-4 may be arranged in such a manner that the extension direction of the first electrode 130 of the first liquid crystal cell 120-1 forms an angle of not less than 0° and not more than 10° with the extension direction of the first electrode 130 of the second liquid crystal cell 120-2, and forms an angle of not less than 80° and not more than 90° with respect to the extension direction of the first electrode 130 of the third liquid crystal cell 120-3 and the fourth liquid crystal cell 120-4.

[0140] The driving method of the optical element 112 involved in this modification example 1 is also arbitrary, and it can also be driven as shown in Table 10. That is, the second electrode 132 of the first liquid crystal cell 120-1, the first electrode 130 of the second liquid crystal cell 120-2, and the first electrode 130 and the second electrode 132 of the third liquid crystal cell 120-3 and the fourth liquid crystal cell 120-4 can also be driven. In this case, the polarization component in the y direction of the incident light is diffused in the y direction by the first liquid crystal cell 120-1, the third liquid crystal cell 120-3, and the fourth liquid crystal cell 120-4, and then optically rotated twice by the first liquid crystal cell 120-1 and the second liquid crystal cell 120-2, so that the polarization component in the y direction diffused three times in the y direction is given. On the other hand, the polarization component in the x direction is diffused in the x direction by the second liquid crystal unit 120-2, the third liquid crystal unit 120-3, and the fourth liquid crystal unit 120-4, and is optically rotated twice by the first liquid crystal unit 120-1 and the second liquid crystal unit 120-2, so that the polarization component in the x direction diffused three times in the x direction is given. As a result, the incident light given a circular irradiation area can be changed into light given a cross-shaped irradiation area. In addition, since the two polarization components are diffused multiple times (at least 3 times), the coloring of the light can also be effectively suppressed.

[0141] [Table 10]

[0142] Table 10 Behavior of light incident on the optical element 112 (5)

[0143]

[0144] a 90° optical rotation using the first liquid crystal unit

[0145] b 90° optical rotation using the second liquid crystal unit

[0146] 3. Modification 2

[0147] In the case where the optically active liquid crystal cell 121 is used as the first liquid crystal cell 120-1 and the second liquid crystal cell 120-2 as in Modification 1, Fig.16 As shown, the first liquid crystal unit 120-1 to the fourth liquid crystal unit 120-4 can also be configured in a manner that the extension direction of the first electrode 130 of the first liquid crystal unit 120-1 is at an angle greater than 0° and less than 10° relative to the extension direction of the first electrode 130 of the third liquid crystal unit 120-3, and is at an angle greater than 80° and less than 90° relative to the extension direction of the first electrode 130 of the second liquid crystal unit 120-2 and the fourth liquid crystal unit 120-4.

[0148] The driving method of the optical element 112 involved in this modification example 2 is also arbitrary. For example, as shown in Table 11, the same driving method as that of the modification example 1 may be adopted. That is, the second electrode 132 of the first liquid crystal cell 120-1, the first electrode 130 of the second liquid crystal cell 120-2, and the first electrode 130 and the second electrode 132 of the third liquid crystal cell 120-3 and the fourth liquid crystal cell 120-4 may be driven. In this case, the polarization component in the y direction of the incident light is diffused in the y direction by the first liquid crystal cell 120-1 to the fourth liquid crystal cell 120-4, and then optically rotated twice by the first liquid crystal cell 120-1 and the second liquid crystal cell 120-2, thereby providing the polarization component in the y direction diffused four times in the y direction. On the other hand, the polarization component in the x direction is diffused in the x direction by the third liquid crystal cell 120-3 and the fourth liquid crystal cell 120-4, and optically rotated twice by the first liquid crystal cell 120-1 and the second liquid crystal cell 120-2, thereby providing the polarization component in the x direction diffused twice in the x direction. As a result, incident light that is applied to a circular irradiation area can be changed into light that is applied to a cross-shaped irradiation area. In addition, since at least one polarization component is diffused multiple times (at least three times), coloring of light can also be effectively suppressed.

[0149] [Table 11]

[0150] Table 11 Behavior of light incident on optical element 112 (6)

[0151]

[0152] a 90° optical rotation using the first liquid crystal unit

[0153] b 90° optical rotation using the second liquid crystal unit

[0154] 4. Modification 3

[0155] When two optically active liquid crystal cells 121 are used as in Modification 1 and Modification 2, Fig.17 As shown, the optically active liquid crystal cell 121 may be used as the first liquid crystal cell 120-1 and the third liquid crystal cell 120-3. In this case, for example, the first liquid crystal cell 120-1 to the fourth liquid crystal cell 120-4 may be arranged in such a manner that the extending direction of the first electrode 130 of the first liquid crystal cell 120-1 forms an angle of 0° or more and 10° or less with respect to the extending direction of the first electrode 130 of the second liquid crystal cell 120-2, and forms an angle of 80° or more and 90° or less with respect to the extending direction of the first electrode 130 of the third liquid crystal cell 120-3 and the fourth liquid crystal cell 120-4.

[0156] The driving method of the optical element 112 involved in this modification example 3 is also arbitrary. For example, the optical element 112 may be driven as shown in Table 12. That is, the second electrodes 132 of the first liquid crystal unit 120-1 and the third liquid crystal unit 120-3 may be driven without driving other electrodes. In this case, the polarization component in the y direction of the incident light is diffused in the y direction by the first liquid crystal unit 120-1, and then optically rotated four times by the first liquid crystal unit 120-1 to the fourth liquid crystal unit 120-4, thereby providing the polarization component in the y direction that has been diffused once in the y direction. On the other hand, the polarization component in the x direction is diffused in the x direction by the third liquid crystal unit 120-3, and optically rotated four times by the first liquid crystal unit 120-1 to the fourth liquid crystal unit 120-4, thereby providing the polarization component in the x direction that has been diffused once in the x direction. As a result, the incident light that has been provided with a circular irradiation area can be changed into light that has been provided with a cross-shaped irradiation area.

[0157] [Table 12]

[0158] Table 12 Behavior of light incident on optical element 112 (7)

[0159]

[0160] a 90° optical rotation using the first liquid crystal unit

[0161] b 90° optical rotation using the second liquid crystal unit

[0162] c 90° optical rotation using the third liquid crystal unit

[0163] d 90° optical rotation using the fourth liquid crystal unit

[0164] 5. Modification 4

[0165] When two optically active liquid crystal cells 121 are used as in Modifications 1 to 3, Fig.18 As shown, the optically active liquid crystal cell 121 is used as the first liquid crystal cell 120-1 and the fourth liquid crystal cell 120-4. In this case, for example, the first liquid crystal cell 120-1 to the fourth liquid crystal cell 120-4 may be arranged in such a manner that the extending direction of the first electrode 130 of the first liquid crystal cell 120-1 forms an angle of 0° or more and 10° or less with respect to the extending direction of the first electrode 130 of the second liquid crystal cell 120-2, and forms an angle of 80° or more and 90° or less with respect to the extending direction of the first electrode 130 of the third liquid crystal cell 120-3 and the fourth liquid crystal cell 120-4.

[0166] The driving method of the optical element 112 involved in this modification example 4 is also arbitrary, and the optical element 112 may be driven as shown in Table 13, for example. That is, the first electrode 130 of the third liquid crystal cell 120-3, the first liquid crystal cell 120-1, the third liquid crystal cell 120-3, and the second electrode 132 of the fourth liquid crystal cell 120-4 may be driven without driving other electrodes. In this case, the polarization component in the y direction of the incident light is diffused in the y direction by the first liquid crystal cell 120-1 and the third liquid crystal cell 120-3, and is optically rotated three times by the first liquid crystal cell 120-1, the second liquid crystal cell 120-2, and the fourth liquid crystal cell 120-4, thereby providing the polarization component in the x direction diffused twice in the y direction. On the other hand, the polarization component in the x direction is diffused in the x direction by the third liquid crystal cell 120-3 and the fourth liquid crystal cell 120-4, and optically rotated three times by the first liquid crystal cell 120-1, the second liquid crystal cell 120-2, and the fourth liquid crystal cell 120-4, so that the polarization component in the y direction diffused twice in the x direction is given. As a result, the incident light that gives a circular irradiation area can be changed into light that gives a cross-shaped irradiation area.

[0167] [Table 13]

[0168] Table 13 Behavior of light incident on the optical element 112 (8)

[0169]

[0170] a 90° optical rotation using the first liquid crystal unit

[0171] b 90° optical rotation using the second liquid crystal unit

[0172] c 90° optical rotation using the fourth liquid crystal unit

[0173] 6. Modification 5

[0174] When the optically active liquid crystal cell 121 is used as the first liquid crystal cell 120-1 and the fourth liquid crystal cell 120-4 as in Modification 4, Fig.19 As shown, the first liquid crystal unit 120-1 to the fourth liquid crystal unit 120-4 can also be configured in a manner such that the extension direction of the first electrode 130 of the first liquid crystal unit 120-1 is at an angle greater than 0° and less than 10° relative to the extension direction of the first electrode 130 of the second liquid crystal unit 120-2, the third liquid crystal unit 120-3 and the fourth liquid crystal unit 120-4.

[0175] The driving method of the optical element 112 involved in this modification example 5 is also arbitrary. For example, as shown in Table 14, the same driving method as in modification example 4 may be adopted. That is, the first electrode 130 of the third liquid crystal cell 120-3, the first liquid crystal cell 120-1, the third liquid crystal cell 120-3, and the second electrode 132 of the fourth liquid crystal cell 120-4 may be driven without driving other electrodes. In this case, the polarization component in the y direction of the incident light is diffused in the y direction by the first liquid crystal cell 120-1, the third liquid crystal cell 120-3, and the fourth liquid crystal cell 120-4, and is optically rotated three times by the first liquid crystal cell 120-1, the second liquid crystal cell 120-2, and the fourth liquid crystal cell 120-4, thereby providing the polarization component in the x direction diffused three times in the y direction. On the other hand, the polarization component in the x direction is diffused in the x direction by the third liquid crystal unit 120-3, and is optically rotated three times by the first liquid crystal unit 120-1, the second liquid crystal unit 120-2, and the fourth liquid crystal unit 120-4, thereby providing a polarization component in the y direction that has been diffused once in the x direction. As a result, the incident light that is provided with a circular irradiation area can be changed into light that is provided with a cross-shaped irradiation area. In addition, since at least one polarization component is diffused multiple times (at least three times), the coloring of light can also be effectively suppressed.

[0176] [Table 14]

[0177] Table 14 Behavior of light incident on the optical element 112 (9)

[0178]

[0179] a 90° optical rotation using the first liquid crystal unit

[0180] b 90° optical rotation using the second liquid crystal unit

[0181] c 90° optical rotation using the fourth liquid crystal unit

[0182] As described above, by using the optical elements 110 and 112 according to the embodiment of the present invention, the light from the light source 102 can be changed to light that is given an arbitrary irradiation area. In addition, by appropriately selecting the structure and arrangement of the plurality of liquid crystal cells 120 in the optical elements 110 and 112, the coloring of the light whose light distribution has been changed can be suppressed. Therefore, the lighting device 100 including the optical elements 110 and 112 according to the embodiment of the present invention can function as a lighting device that can give various irradiation areas.

[0183] As embodiments of the present invention, the above embodiments can be appropriately combined and implemented as long as they are not contradictory. In addition, based on the display device of each embodiment, those skilled in the art appropriately add, delete or change the design of the components, or add, omit or change the conditions of the processes, and as long as they have the gist of the present invention, they are also included in the scope of the present invention.

[0184] Even if there are other effects different from the effects brought about by the forms of the above-mentioned embodiments, the effects that are clear based on the description of this specification or the effects that can be easily predicted by those skilled in the art can of course be understood as the effects brought about by the present invention.

[0185] Description of Reference Numerals

[0186] 100, lighting device; 102, light source; 110, optical element; 112, optical element; 114, light emitting element; 120, liquid crystal unit; 120-1, first liquid crystal unit; 120-2, second liquid crystal unit; 120-3, third liquid crystal unit; 120-4, fourth liquid crystal unit; 121, optically active liquid crystal unit; 122, substrate; 124, counter substrate; 126, sealing material; 128, liquid crystal layer; 130, first electrode; 130a, edge ; 132, second electrode; 134-1, first wiring; 134-2, second wiring; 134-3, third wiring; 134-4, fourth wiring; 136-1, terminal; 136-2, terminal; 136-3, terminal; 136-4, terminal; 140, first orientation film; 142, second orientation film; 144, arrow; 146, arrow; 148, arrow; 150, arrow; 152, polarization component; 154, polarization component; 160, adhesive layer.

Claims

1. An optical element, The optical element includes a first liquid crystal cell, a second liquid crystal cell, a third liquid crystal cell, and a fourth liquid crystal cell which are sequentially arranged in an overlapping manner. The first liquid crystal cell, the second liquid crystal cell, the third liquid crystal cell and the fourth liquid crystal cell each have: A plurality of first electrodes are arranged in a stripe shape and extend along a first extension direction; a first alignment film on the plurality of first electrodes; a liquid crystal layer on the first alignment film; a second alignment film on the liquid crystal layer; as well as A plurality of second electrodes are located on the second alignment film, arranged in a stripe shape, and extend along a second extension direction intersecting the first extension direction. In each of the first liquid crystal cell, the second liquid crystal cell, the third liquid crystal cell, and the fourth liquid crystal cell, The first orientation film and the second orientation film are configured to align the liquid crystal molecules contained in the liquid crystal layer in first orientation directions and second orientation directions that intersect each other, respectively, when no voltage is applied to the plurality of first electrodes and the plurality of second electrodes, the angle between the first extension direction and the first orientation direction is within 10°, the angle between the second extension direction and the second orientation direction is within 10°, the first extension direction of the first liquid crystal unit is at an angle of greater than 0° and less than 10° relative to the first extension direction of the second liquid crystal unit, and is at an angle of greater than 80° and less than 90° relative to the first extension directions of the third liquid crystal unit and the fourth liquid crystal unit.

2. The optical element according to claim 1, wherein In each of the first liquid crystal cell, the second liquid crystal cell, the third liquid crystal cell, and the fourth liquid crystal cell, The plurality of first electrodes are configured to be applied with a first alternating voltage in opposite phases between adjacent first electrodes. The plurality of second electrodes are configured to receive a second AC voltage applied thereto so that the second AC voltage has opposite phases between adjacent second electrodes.

3. The optical element according to claim 1, wherein In at least one of the first liquid crystal cell, the second liquid crystal cell, the third liquid crystal cell, and the fourth liquid crystal cell, Each of the plurality of first electrodes and the plurality of second electrodes is bent so as to have a plurality of straight line portions.

4. The optical element according to claim 3, wherein: In each of the plurality of first electrodes, an extending direction of at least one of the plurality of straight line portions is inclined from the first alignment direction, In each of the plurality of second electrodes, an extending direction of at least one of the plurality of straight line portions is inclined from the second alignment direction.

5. The optical element according to claim 1, wherein In at least one of the first liquid crystal cell, the second liquid crystal cell, the third liquid crystal cell, and the fourth liquid crystal cell, A front end of at least one of the plurality of first electrodes has an acute angle, A front end of at least one of the plurality of second electrodes has an acute angle.

6. A lighting device comprising: The optical element according to claim 1; and The light source is located above the optical element and is configured on one side of the first liquid crystal unit.

7. An optical element, The optical element includes a first liquid crystal cell, a second liquid crystal cell, a third liquid crystal cell, and a fourth liquid crystal cell which are sequentially arranged in an overlapping manner. The first liquid crystal cell, the second liquid crystal cell, the third liquid crystal cell and the fourth liquid crystal cell each have: A plurality of first electrodes are arranged in a stripe shape and extend along a first extension direction; a first alignment film on the plurality of first electrodes; a liquid crystal layer on the first alignment film; a second alignment film on the liquid crystal layer; as well as A plurality of second electrodes are located on the second alignment film, arranged in a stripe shape, and extend along a second extension direction intersecting the first extension direction. In each of the first liquid crystal cell, the second liquid crystal cell, the third liquid crystal cell, and the fourth liquid crystal cell, The first alignment film and the second alignment film are configured to align the liquid crystal molecules included in the liquid crystal layer in first alignment directions and second alignment directions that intersect each other when no voltage is applied to the plurality of first electrodes and the plurality of second electrodes, and in at least one of the first liquid crystal cell, the second liquid crystal cell, the third liquid crystal cell, and the fourth liquid crystal cell, The angle between the first extension direction and the first alignment direction is within 10°, the angle between the second extension direction and the second alignment direction is within 10°, and in the liquid crystal cells other than the at least one liquid crystal cell, The angle between the first extension direction and the first orientation direction is greater than or equal to 80° and less than or equal to 90°, An angle between the second stretching direction and the second alignment direction is greater than or equal to 80° and less than or equal to 90°.

8. The optical element according to claim 7, wherein: The at least one liquid crystal unit includes the first liquid crystal unit, the second liquid crystal unit and the third liquid crystal unit, The first extension direction of the first liquid crystal unit forms an angle of greater than 0° and less than 10° relative to the first extension direction of the second liquid crystal unit, and forms an angle of greater than 80° and less than 90° relative to the first extension directions of the third liquid crystal unit and the fourth liquid crystal unit.

9. The optical element according to claim 7, wherein: The at least one liquid crystal cell includes the third liquid crystal cell and the fourth liquid crystal cell, The first extension direction of the first liquid crystal unit forms an angle of greater than 0° and less than 10° relative to the first extension direction of the second liquid crystal unit, and forms an angle of greater than 80° and less than 90° relative to the first extension directions of the third liquid crystal unit and the fourth liquid crystal unit.

10. The optical element according to claim 7, wherein: The at least one liquid crystal cell includes the third liquid crystal cell and the fourth liquid crystal cell, The first extension direction of the first liquid crystal unit forms an angle of greater than 0° and less than 10° relative to the first extension direction of the third liquid crystal unit, and forms an angle of greater than 80° and less than 90° relative to the first extension directions of the second liquid crystal unit and the fourth liquid crystal unit.

11. The optical element according to claim 7, wherein: The at least one liquid crystal cell includes the second liquid crystal cell and the fourth liquid crystal cell, The first extension direction of the first liquid crystal unit forms an angle of greater than 0° and less than 10° relative to the first extension direction of the second liquid crystal unit, and forms an angle of greater than 80° and less than 90° relative to the first extension directions of the third liquid crystal unit and the fourth liquid crystal unit.

12. The optical element according to claim 7, wherein: The at least one liquid crystal cell includes the second liquid crystal cell and the third liquid crystal cell, The first extension direction of the first liquid crystal unit forms an angle of greater than 0° and less than 10° relative to the first extension direction of the second liquid crystal unit, and forms an angle of greater than 80° and less than 90° relative to the first extension directions of the third liquid crystal unit and the fourth liquid crystal unit.

13. The optical element according to claim 7, wherein: The at least one liquid crystal cell includes the second liquid crystal cell and the third liquid crystal cell, The first extension direction of the first liquid crystal cell forms an angle of not less than 0° and not more than 10° with respect to the first extension directions of the second liquid crystal cell, the third liquid crystal cell, and the fourth liquid crystal cell.

14. The optical element according to claim 7, wherein: In each of the first liquid crystal cell, the second liquid crystal cell, the third liquid crystal cell, and the fourth liquid crystal cell, The plurality of first electrodes are configured to be applied with a first alternating voltage in opposite phases between adjacent first electrodes. The plurality of second electrodes are configured to receive a second AC voltage applied thereto so that the second AC voltage has opposite phases between adjacent second electrodes.

15. The optical element according to claim 7, wherein: In at least one of the first liquid crystal cell, the second liquid crystal cell, the third liquid crystal cell, and the fourth liquid crystal cell, Each of the plurality of first electrodes and the plurality of second electrodes is bent so as to have a plurality of straight line portions.

16. The optical element according to claim 15, wherein: In each of the plurality of first ones, an extending direction of at least one of the plurality of straight line portions is inclined from the first orientation direction, In each of the plurality of second alignment directions, an extending direction of at least one of the plurality of straight line portions is inclined from the second alignment direction.

17. The optical element according to claim 7, wherein: In at least one of the first liquid crystal cell, the second liquid crystal cell, the third liquid crystal cell, and the fourth liquid crystal cell, At least one of the plurality of first electrodes has a front end with an acute angle, At least one of the plurality of second electrodes has a front end with an acute angle.

18. A lighting device comprising: The optical element according to claim 7; and The light source is located above the optical element and is configured on one side of the first liquid crystal unit.

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