Optical element and lighting device including the optical element

Abstract

To provide a luminaire capable of arbitrarily changing an irradiation range of a light source.SOLUTION: A luminaire comprises a light source, a first liquid crystal panel on the light source, and a second liquid crystal panel on the first liquid crystal panel. Each of the first liquid crystal panel and the second liquid crystal panel includes: a substrate; a plurality of bottom electrodes arranged in a stripe pattern on the substrate; a first orientation film on the plurality of bottom electrodes; a liquid crystal layer on the first orientation film; a second orientation film arranged on the liquid crystal layer with an orientation direction orthogonal to the first orientation film; a plurality of upper electrodes arranged in a stripe pattern on the second orientation film so as to be orthogonal to the plurality of bottom electrodes; and a counter substrate on the plurality of upper electrodes. An extending direction of the plurality of bottom electrodes of the first liquid crystal panel and an extending direction of the plurality of bottom electrodes of the second liquid crystal panel form a first angle of 0° or more and 5° or less.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] One embodiment of the present invention relates to a lighting device. For example, one embodiment of the present invention relates to a lighting device that can arbitrarily control an illumination range. [Background technology]

[0002] In recent years, lighting devices have been developed that can control the illumination range and illumination distance of a light source by using a liquid crystal lens to control the light emitted from the light source. For example, the lighting devices disclosed in Patent Documents 1 to 3 include a liquid crystal panel with electrodes that sandwich a liquid crystal layer, and a light source that overlaps the liquid crystal panel. In these lighting devices, the orientation of liquid crystal molecules in the liquid crystal layer is controlled by the electric field between the electrodes, causing the liquid crystal panel to function as a lens, thereby controlling the light distribution. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-230887 [Patent Document 2] Japanese Patent Application Laid-Open No. 2016-057541 [Patent Document 3] Japanese Patent Application Laid-Open No. 2019-169435 Summary of the Invention [Problem to be solved by the invention]

[0004] An object of one embodiment of the present invention is to provide an illumination device that can arbitrarily change the illumination range of a light source. Alternatively, an object of one embodiment of the present invention is to provide an illumination device that can diversify the illumination range of a light source and can suppress coloring of light and the occurrence of moire. [Means for solving the problem]

[0005] One embodiment of the present invention is a lighting device. The lighting device includes a light source, a first liquid crystal panel on the light source, and a second liquid crystal panel on the first liquid crystal panel. Each of the first and second liquid crystal panels includes a substrate, a plurality of lower electrodes arranged in a stripe pattern on the substrate, a first alignment film on the plurality of lower electrodes, a liquid crystal layer on the first alignment film, a second alignment film arranged on the liquid crystal layer and having an alignment direction perpendicular to that of the first alignment film, a plurality of upper electrodes arranged in a stripe pattern on the second alignment film and perpendicular to the plurality of lower electrodes, and a counter substrate on the plurality of upper electrodes. A first angle formed between the extension direction of the plurality of lower electrodes of the first liquid crystal panel and the extension direction of the plurality of lower electrodes of the second liquid crystal panel is between 0° and 5°. In each of the first and second liquid crystal panels, first to third lower electrodes are arbitrarily selected from the plurality of lower electrodes and arranged consecutively, and the distance between the first lower electrode and the second lower electrode is different from the distance between the second lower electrode and the third lower electrode. Similarly, in each of the first liquid crystal panel and the second liquid crystal panel, for first to third upper electrodes that are arbitrarily selected from a plurality of upper electrodes and arranged consecutively, the distance between the first upper electrode and the second upper electrode is different from the distance between the second upper electrode and the third upper electrode.

[0006] One embodiment of the present invention is a lighting device. This lighting device includes a light source and first to fourth liquid crystal panels stacked in order on the light source. Each of the first and second liquid crystal panels includes a substrate, a plurality of lower electrodes arranged in a stripe pattern on the substrate, a first alignment film arranged on the plurality of lower electrodes, a liquid crystal layer on the first alignment film, a second alignment film arranged on the liquid crystal layer and having an alignment direction perpendicular to that of the first alignment film, and a counter substrate on the second alignment film. Each of the third and fourth liquid crystal panels includes a substrate, a first alignment film on the substrate, a liquid crystal layer on the first alignment film, a second alignment film arranged on the liquid crystal layer and having an alignment direction perpendicular to that of the first alignment film, a plurality of upper electrodes arranged in a stripe pattern on the second alignment film, and a counter substrate on the plurality of upper electrodes. The plurality of lower electrodes of the first and second liquid crystal panels are perpendicular to the extension direction of the plurality of upper electrodes of the third and fourth liquid crystal panels. In each of the first and second liquid crystal panels, for first to third consecutively arranged lower electrodes arbitrarily selected from the plurality of lower electrodes, the distance between the first lower electrode and the second lower electrode is different from the distance between the second lower electrode and the third electrode.In each of the third and fourth liquid crystal panels, for first to third consecutively arranged upper electrodes arbitrarily selected from the plurality of upper electrodes, the distance between the first upper electrode and the second upper electrode is different from the distance between the second upper electrode and the third upper electrode.

[0007] One embodiment of the present invention is a lighting device. This lighting device includes a light source and first to fourth liquid crystal panels stacked in order on the light source. Each of the first and second liquid crystal panels includes a substrate, a first alignment film disposed on the substrate, a liquid crystal layer on the first alignment film, a second alignment film disposed on the liquid crystal layer and having an alignment direction perpendicular to that of the first alignment film, multiple upper electrodes arranged in a stripe pattern on the second alignment film, and a counter substrate on the multiple upper electrodes. Each of the third and fourth liquid crystal panels includes a substrate, multiple lower electrodes arranged in a stripe pattern on the substrate, a first alignment film disposed on the multiple lower electrodes, a liquid crystal layer on the first alignment film, a second alignment film disposed on the liquid crystal layer and having an alignment direction perpendicular to that of the first alignment film, and a counter substrate on the second alignment film. The extension direction of the multiple upper electrodes of the first and second liquid crystal panels is perpendicular to the extension direction of the multiple lower electrodes of the third and fourth liquid crystal panels. In each of the first and second liquid crystal panels, for first to third upper electrodes arbitrarily selected from the plurality of upper electrodes and arranged consecutively, the distance between the first upper electrode and the second upper electrode is different from the distance between the second upper electrode and the third upper electrode.In each of the third and fourth liquid crystal panels, for first to third lower electrodes arbitrarily selected from the plurality of lower electrodes and arranged consecutively, the distance between the first lower electrode and the second lower electrode is different from the distance between the second lower electrode and the third lower electrode. [Brief explanation of the drawings]

[0008] [Figure 1A] 1 is a schematic perspective view of an illumination device according to an embodiment of the present invention. [Figure 1B] FIG. 2 is a schematic end view of a light source of the lighting device according to the embodiment of the present invention. [Figure 2A] FIG. 2 is a schematic top view of a light source of the lighting device according to the embodiment of the present invention. [Figure 2B] FIG. 2 is a schematic end view of a light source of the lighting device according to the embodiment of the present invention. [Figure 3] FIG. 2 is a schematic end view of a liquid crystal panel of the lighting device according to the embodiment of the present invention. [Figure 4A]FIG. 2 is a schematic top view of a liquid crystal panel of the lighting device according to the embodiment of the present invention. [Figure 4B] FIG. 2 is a schematic top view of a liquid crystal panel of the lighting device according to the embodiment of the present invention. [Figure 5] FIG. 2 is a schematic top view of a liquid crystal panel of the lighting device according to the embodiment of the present invention. [Figure 6] FIG. 2 is a schematic top view of a liquid crystal panel of the lighting device according to the embodiment of the present invention. [Figure 7] 1 is a schematic perspective view illustrating the operating principle of a lighting device according to an embodiment of the present invention. [Figure 8A] 5A to 5C are schematic diagrams illustrating the operation behavior of the lighting device according to the embodiment of the present invention. [Figure 8B] 5A to 5C are schematic diagrams illustrating the operation behavior of the lighting device according to the embodiment of the present invention. [Figure 9A] FIG. 2 is a schematic top view of a liquid crystal panel of the lighting device according to the embodiment of the present invention. [Figure 9B] FIG. 2 is a schematic top view of a liquid crystal panel of the lighting device according to the embodiment of the present invention. [Figure 10] FIG. 2 is a schematic perspective view of a liquid crystal panel of the lighting device according to the embodiment of the present invention. [Figure 11A] FIG. 2 is a schematic top view of a liquid crystal panel of the lighting device according to the embodiment of the present invention. [Figure 11B] FIG. 2 is a schematic top view of a liquid crystal panel of the lighting device according to the embodiment of the present invention. [Figure 12A] FIG. 2 is a schematic diagram showing the arrangement of lower electrodes in a liquid crystal panel of the lighting device according to the embodiment of the present invention. [Figure 12B] FIG. 2 is a schematic diagram showing the arrangement of lower electrodes in a liquid crystal panel of the lighting device according to the embodiment of the present invention. [Figure 12C] FIG. 2 is a schematic diagram showing the arrangement of lower electrodes in a liquid crystal panel of the lighting device according to the embodiment of the present invention. [Figure 13] FIG. 2 is a schematic perspective view of a liquid crystal panel of the lighting device according to the embodiment of the present invention. [Figure 14] FIG. 2 is a schematic perspective view of a liquid crystal panel of the lighting device according to the embodiment of the present invention. [Figure 15] FIG. 2 is a schematic end view of a liquid crystal panel of the lighting device according to the embodiment of the present invention. [Figure 16] FIG. 2 is a schematic top view of a liquid crystal panel of the lighting device according to the embodiment of the present invention. [Figure 17A] 10 is a photograph of an irradiated surface obtained by the lighting device of the example. [Figure 17B] 10 is a photograph of an irradiated surface obtained by the lighting device of the example. [Figure 17C] 10 is a photograph of an irradiated surface obtained by the lighting device of the example. [Figure 17D] 10 is a photograph of an irradiated surface obtained by the lighting device of the example. [Figure 17E] 10 is a photograph of an irradiated surface obtained by the lighting device of the example. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, various embodiments of the present invention will be described with reference to the drawings, etc. However, the present invention can be embodied in various forms without departing from the spirit of the present invention, and should not be construed as being limited to the description of the embodiments exemplified below.

[0010] In order to clarify the description, the drawings may show the width, thickness, shape, etc. of each part schematically compared to the actual embodiment, but these are merely examples and do not limit the interpretation of the present invention. In this specification and each drawing, elements having the same function as those described in the previous drawings may be given the same reference numerals, and duplicated explanations may be omitted. This reference numeral is used to collectively represent multiple identical or similar structures, and when these are individually represented, a hyphen and a natural number are added after the reference numeral.

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

[0012] In this specification and claims, the expression that two structures are "orthogonal" includes not only a state in which the two structures intersect perpendicularly (90°) but also a state in which the two structures intersect at an angle of 90°±10°. Similarly, the expression that two structures are "parallel" includes not only a case in which the angle between the extension directions of the two structures is 0° but also a case in which the angle is 0°±10°.

[0013] First Embodiment In this embodiment, an illumination device 100, which is one embodiment of the present invention, will be described.

[0014] FIG. 1A is a schematic perspective view of a lighting device 100. As shown in FIG. 1A, the lighting device 100 basically includes a light source 110 and two optical elements that overlap the light source 110 and are provided on the light source 110. One optical element is a first liquid crystal panel 120-1 on the light source 110, and the other is a second liquid crystal panel 120-2 provided on the first liquid crystal panel 120-1. The first liquid crystal panel 120-1 and the second liquid crystal panel 120-2 may be in direct contact with each other or may be fixed to each other using an adhesive (not shown). For convenience, in the following drawings, including FIG. 1A, the principal surfaces of the first liquid crystal panel 120-1 and the second liquid crystal panel 120-2 are defined as the xy plane, and the direction perpendicular to this plane is defined as the z direction. The x and y directions are perpendicular to each other, but according to the definition above, the angle between the x and y directions is within the range of 90°±10°. For example, the x and y directions are parallel to the sides of the substrate 122 or the counter substrate 124, which will be described later. Each component will be described in detail below.

[0015] 1.Light source The light source 110 is configured to emit highly directional collimated light to the first liquid crystal panel 120-1 and the second liquid crystal panel 120-2. Specifically, as shown in the schematic end view (FIG. 2B) taken along the dashed line AA' in FIG. 1A, the light source 110 includes a reflector 112 having a recess 112a, and one or more light-emitting elements 114 provided in the recess 112a. There are no restrictions on the shape of the reflector 112 in the xy plane, and it may be set appropriately depending on the environment in which the lighting device 100 is installed. For example, as shown in FIG. 1A, the shape of the reflector 112 in the xy plane may be a square, or may be a circle, ellipse, or polygon, although not shown.

[0016] The material for the reflector 112 can be selected arbitrarily, but may be, for example, a metal such as aluminum or stainless steel, a polymer such as polyimide, polycarbonate, or acrylic resin, or an inorganic oxide such as glass. However, as indicated by the arrow in FIG. 1B , the reflector 112 reflects and collects light from the light-emitting element 114, providing collimated light to the liquid crystal panel 120. For this reason, when the reflector 112 is made of a material that transmits visible light, such as glass or a polymer, it is preferable to form the surface of the recess 112a with a film that has high reflectivity for visible light. Examples of such a film include a film containing a metal such as aluminum, silver, gold, chromium, or stainless steel, and a laminate of a thin film containing a high-refractive-index material such as titanium oxide or tantalum oxide and a thin film containing a low-refractive-index material such as silicon oxide or magnesium fluoride. The shape of the recess 112a is appropriately adjusted so that the light from the light-emitting element 114 within the recess 112a is reflected to obtain highly directional light.

[0017] The reflector 112 may be provided with a plurality of recesses 112a. For example, as shown in the schematic top view of FIG. 2A and the schematic end view (FIG. 2B) along the chain line BB' in FIG. 2A, the reflector 112 may be provided with a plurality of recesses 112a. There are no restrictions on the planar shape of the recesses 112a on the upper surface of the reflector 112 (the upper surface closer to the liquid crystal panel 120), and they may be circular as shown in FIG. 2A or polygonal, such as a rectangle. One or a plurality of light-emitting elements 114 are disposed in the recesses 112a. When a plurality of recesses 112a are provided, light from each recess 112a illuminates a part of the liquid crystal panel 120.

[0018] The light-emitting element 114 is an element that emits light when supplied with current, and there are no restrictions on its structure. A typical example is a light-emitting diode (LED). A light-emitting diode basically comprises an electroluminescent element in which an inorganic light-emitting material, such as gallium nitride or indium-containing gallium nitride, is sandwiched between a pair of electrodes, and a protective film that protects the electroluminescent element. The light emitting element 114 is configured to emit visible light by electroluminescence. The light emission color of each light-emitting element 114 can also be selected arbitrarily. For example, one or more light-emitting elements 114 that emit white light may be provided in each recess 112a. Alternatively, the light source 110 may be configured so that light of various colors can be emitted from the recess 112a by providing a red-emitting light-emitting element 114, a green-emitting light-emitting element 114, and a blue-emitting light-emitting element 114 in the recess 112a.

[0019] There is no restriction on the size of each light emitting element 114. For example, the area occupied by each element is 1.0×10 4 μm 2 Over 1.0 x 10 6 μm 2 Below, 4.0 x 10 4 μm 2 Over 5.0 x 10 5 μm 2 or less, or 9.0 x 10 4 μm 2 Over 2.5 x 10 5 μm 2The following light emitting diodes can be used: As an example, a so-called micro LED having a size of about 320 μm×300 μm can be used as the light emitting element 114.

[0020] 2. LCD panel The two liquid crystal panels 120 may have the same structure. FIG. 3 shows a partial schematic end view of one liquid crystal panel 120 (here, the first liquid crystal panel 120-1). As shown in FIG. 3, each liquid crystal panel 120 basically comprises a substrate 122 and a counter substrate 124 facing each other, a plurality of lower electrodes 130 sandwiched between them, a first alignment film 134 on the plurality of lower electrodes 130, a liquid crystal layer 138 on the first alignment film, a second alignment film 136 on the liquid crystal layer 138, and a plurality of upper electrodes 132 on the second alignment film 136. Each liquid crystal panel 120 may optionally include an undercoat 126 or an overcoat 128 between the substrate 122 and the lower electrode 130 and between the upper electrode 132 and the counter substrate 124, respectively, which function as protective films to prevent impurities from entering the liquid crystal layer 138.

[0021] 2-1. Substrate and opposing substrate The substrate 122 and the counter substrate 124 are bonded to each other via a frame-shaped sealant, and function as base materials for supporting the plurality of lower electrodes 130 and the plurality of upper electrodes 132, respectively, and also seal the liquid crystal layer 138. Since the substrate 122 and the counter substrate 124 transmit light from the light source 110 to exhibit an illumination function, they preferably contain a material that exhibits high transmittance for light from the light emitting element 114. Therefore, it is preferable that the substrate 122 and the counter substrate 124 be made to contain, for example, glass, quartz, or a polymer material such as polyimide, polycarbonate, polyester, or acrylic resin.

[0022] 2-2. Lower electrode and upper electrode (1) Overview The plurality of lower electrodes 130 are provided on the substrate 122 so as to be in contact with the substrate 122 or via an undercoat 126 (FIG. 3). The undercoat can be formed of one or more films containing a silicon-containing inorganic compound such as silicon nitride or silicon oxide. In order to impart high light transmittance to the liquid crystal panel 120, the lower electrodes 130 are preferably formed of a conductive oxide that exhibits high transmittance to visible light, such as indium tin oxide (ITO) or indium zinc oxide (IZO).

[0023] 4A shows a schematic top view of multiple lower electrodes 130 arranged on substrate 122. As can be seen from FIGS. 3 and 4A, the multiple lower electrodes 130 extend in the same direction and are arranged in a stripe pattern. The length of each lower electrode 130 (the length in the direction in which the lower electrodes 130 extend (here, the x direction)) may be selected from the range of 5 cm to 15 cm, or 1 cm to 10 cm, for example.

[0024] Here, the multiple lower electrodes 130 can be divided into one or multiple lower electrode groups 140. The multiple lower electrode groups 140 are arranged in the direction in which the lower electrodes 130 extend (here, the x direction). Focusing on one lower electrode group 140, the multiple lower electrodes 130 are arranged in a row in the y direction, which is perpendicular to the x direction in which the lower electrodes 130 extend. The length of each lower electrode group in the y direction can also be set arbitrarily, for example, from 3 cm to 30 cm or from 10 cm to 20 cm. In each lower electrode group 140, multiple lower electrodes 130-1 selected every other one in the y direction are connected to wiring 144-1 and electrically connected to each other. Therefore, the same potential is simultaneously applied to these lower electrodes 130-1. Meanwhile, the remaining lower electrodes 130-2 are connected to wiring 144-2 and electrically connected to each other. Therefore, the same potential is simultaneously applied to these lower electrodes 130-1 and 130-2, and the lower electrodes 130-1 and 130-2 are electrically independent. Furthermore, the lower electrodes 130-1 and 130-2 alternate in the y direction.

[0025] As shown in FIG. 3, the multiple upper electrodes 132 are provided in contact with the counter substrate 124 or on the counter substrate 124 (below the counter substrate 124 in FIG. 3) via an overcoat 128. A schematic top view of the multiple upper electrodes 132 arranged on the counter substrate 124 side is shown in FIG. 4B. FIG. 4B is a schematic view of the upper electrode 132 as seen from the counter substrate 124 side (planar view from above). Like the lower electrode 130, the multiple upper electrodes 132 are also formed of a conductive oxide that exhibits high transmittance for visible light and are arranged in a striped pattern. However, their extension directions are different. Specifically, as shown in FIG. 4B, the multiple upper electrodes 132 all extend in the y direction, which is perpendicular to the x direction in which the lower electrode 130 extends. Like the lower electrode 130, the multiple upper electrodes 132 can also be divided into one or more upper electrode groups 142. The multiple upper electrode groups 142 are arranged in the y direction in which the upper electrodes 132 extend. Focusing on one upper electrode group 142, the multiple upper electrodes 132 are arranged in a line in the x direction, which is perpendicular to the y direction in which the upper electrodes 132 extend. In each upper electrode group 142, multiple upper electrodes 132-1 selected every other one in the x direction are connected to wiring 146-1 and are electrically connected to each other. Therefore, the same potential is simultaneously applied to these upper electrodes 132-1. Meanwhile, the remaining upper electrodes 132-2 are connected to wiring 146-2 and are electrically connected to each other. Therefore, the same potential is simultaneously applied to these upper electrodes 132-2, and the upper electrodes 132-1 and 132-2 are electrically independent. Furthermore, the upper electrodes 132-1 and 132-2 alternate in the x direction.

[0026] (2) Bottom electrode placement The arrangement of the lower electrodes 130 will be described in detail with reference to Fig. 5. Fig. 5 is a schematic top view of a part of one lower electrode group 140. As shown in Fig. 5, each lower electrode group 140 has a spacing S between adjacent lower electrodes 130. L , the width W of the lower electrode 130 (the length in the direction perpendicular to the extension direction) L , and the pitch P of the lower electrodes 130 L At least one of the above is configured to vary.

[0027] The variation in the interval between adjacent lower electrodes 130 means that the interval S between two lower electrodes 130 adjacent in the y direction L is not constant within one lower electrode group 140. For example, for three lower electrodes 130a, 130b, and 130c that are arbitrarily selected within one lower electrode group 140 and arranged consecutively in the y direction, the interval S between the lower electrodes 130a and 130b is L is the distance S between the bottom electrodes 130b and 130c. L In one lower electrode group 140, the interval S between two adjacent lower electrodes 130 is L Coefficient of variation CV LS The coefficient of variation CV may be 0.18 or more and 0.35 or less, or 0.20 or more and 0.30 or less. LS is the spacing S of the lower electrodes 130 L The distance S between two adjacent bottom electrodes 130 is obtained by dividing the standard deviation of the L may be selected from the range of, for example, 1 μm to 30 μm or 3 μm to 20 μm.

[0028] The width of the lower electrode 130 varies when the width W of the lower electrode 130 in one lower electrode group 140 is L For example, the widths of the three lower electrodes 130a, 130b, and 130c are all different, or at least one of them is different from the other two. L Coefficient of variation CV LW The coefficient of variation CV may be 0.13 or more and 0.35 or less, or 0.15 or more and 0.30 or less. LW is the width W of the lower electrode 130 L The width W of the lower electrode 130 is obtained by dividing the standard deviation of the L may be selected from the range of 3 μm or more and 20 μm or less, or 5 μm or more and 15 μm or less.

[0029] Pitch P of the lower electrodes 130 LThe pitch P of the lower electrodes 130 varies when the pitch P between two adjacent lower electrodes 130 is arbitrarily selected within one lower electrode group 140. L For example, in the case of the three lower electrodes 130a, 130b, and 130c, the pitch P between the lower electrodes 130a and 130b is L is the pitch P between the bottom electrodes 130b and 130c L In one lower electrode group 140, the pitch P between adjacent lower electrodes 130 is L Coefficient of variation CV LP The coefficient of variation CV may be 0.08 or more and 0.25 or less, or 0.09 or more and 0.20 or less. LP is the pitch P between adjacent bottom electrodes 130 L The pitch P is obtained by dividing the standard deviation of L may be selected from the range of 2 μm to 30 μm or 3 μm to 25 μm.

[0030] In each lower electrode group 140, the interval S L and width W L is constant, but the pitch P L may vary. Alternatively, the interval S L The variation is width W L and Pitch P L may be constant, and the width W L is the variation, the interval S L and Pitch P L Alternatively, the width W L is constant, but the interval S L and Pitch P L may vary. Alternatively, the interval S L is constant, but the width W L and Pitch P L Or, the pitch P L is constant, but the width W L and the interval S L may vary. Alternatively, the interval S L , width W L , pitch P LAll of these may vary.

[0031] In one lower electrode group 140, the width W L , interval S L , and pitch P L All the lower electrodes 130 may not have periodic regularity with respect to the width W of a plurality of (for example, 10, 20, 24) successive lower electrodes 130 in the y direction. L , interval S L , and pitch P L This pattern (pattern A in FIG. 5) may be repeated periodically.

[0032] (3) Arrangement of the upper electrode The upper electrodes 132 are also arranged in a similar manner. Fig. 6 shows a schematic top view of a part of one upper electrode group 142. As shown in Fig. 6, each upper electrode group 142 has a spacing S between adjacent upper electrodes 132. U , the width W of the upper electrode 132 (the length in the direction perpendicular to the extension direction) U , and the pitch P of the upper electrodes 132 U At least one of the above is configured to vary.

[0033] The variation in the spacing between adjacent upper electrodes 132 means that the spacing S between two upper electrodes 132 adjacent in the x direction U is not constant within one upper electrode group 142. For example, for three upper electrodes 132a, 132b, and 132c that are arbitrarily selected within one upper electrode group 142 and arranged consecutively in the x direction, the interval S between the upper electrodes 132a and 132b is U is the distance S between the upper electrodes 132b and 132c. U In one upper electrode group 142, the interval S between two adjacent upper electrodes 132 is U Coefficient of variation CV US The coefficient of variation CV may be 0.18 or more and 0.35 or less, or 0.20 or more and 0.30 or less. US is the spacing S of the upper electrodes 132 U The distance S between two adjacent upper electrodes is obtained by dividing the standard deviation of Umay be selected from the range of, for example, 1 μm to 30 μm or 3 μm to 20 μm.

[0034] The width of the upper electrode 132 varies when the width W of the upper electrode 132 in one upper electrode group 142 is U For example, the widths of the three upper electrodes 132a, 132b, and 132c are all different, or at least one of them is different from the other two. U Coefficient of variation CV UW The coefficient of variation CV may be 0.13 or more and 0.35 or less, or 0.15 or more and 0.30 or less. UW is the width W of the upper electrode 132 U The width W of the upper electrode 132 is obtained by dividing the standard deviation of the U may be selected from the range of 3 μm or more and 20 μm or less, or 5 μm or more and 15 μm or less.

[0035] Pitch P of the upper electrodes 132 U The pitch P between the upper electrodes 132 is the length of a straight line parallel to the x direction that connects the center points in the x direction of adjacent upper electrodes 132. The pitch P between the upper electrodes 132 that is arbitrarily selected within one upper electrode group 142 is U For example, in the case of the three upper electrodes 132a, 132b, and 132c, the pitch P between the upper electrodes 132a and 132b is U is the pitch P between the upper electrodes 132b and 132c U In one upper electrode group 142, the pitch P between adjacent upper electrodes 132 is different. U Coefficient of variation CV UP The coefficient of variation CV may be 0.08 or more and 0.25 or less, or 0.09 or more and 0.20 or less. UP is the pitch P between adjacent upper electrodes 132 U The pitch P is obtained by dividing the standard deviation of U may be selected from the range of 2 μm to 30 μm or 3 μm to 25 μm.

[0036] Similar to the lower electrode group 140, each upper electrode group 142 has a spacing S U and width W U is constant, but the pitch P U may vary. Alternatively, the interval S U The variation is width W U and Pitch P U may be constant, and the width W U is the variation, the interval S U and Pitch P U Alternatively, the width W U is constant, but the interval S U and Pitch P U may vary. Alternatively, the interval S U is constant, but the width W U and Pitch P U Or, the pitch P U is constant, but the width W U and the interval S U may vary. Alternatively, the interval S U , width W U , pitch P U All of these may vary.

[0037] In addition, in one upper electrode group 142, the width W U , interval S U , and pitch P U All the upper electrodes 132 may not have periodic regularity with respect to the width W of a plurality of (for example, 10, 20, 24) successive upper electrodes 132 in the x direction. U , interval S U , and pitch P U This pattern (pattern B in FIG. 6) may be repeated periodically.

[0038] 2-3. First alignment film, second alignment film, and liquid crystal layer A first alignment film 134 is provided on the plurality of lower electrodes 130, and a second alignment film 136 is provided on the plurality of upper electrodes 132 (below the upper electrodes 132 in FIG. 3). The substrate 122 and the counter substrate 124 are bonded and fixed together with a sealing material (not shown). A liquid crystal layer 138 is filled in the space formed by the substrate 122, the counter substrate 124, and the sealing material.

[0039] The first alignment film 134 and the second alignment film 136 contain polymers such as polyimide or polyester, and their surfaces are subjected to a rubbing treatment. The rubbing treatment is performed so that the alignment direction of the first alignment film 134 is perpendicular to the direction in which the lower electrode 130 extends (see the arrow in FIG. 4A ) and the alignment direction of the second alignment film 136 is perpendicular to the direction in which the upper electrode 132 extends (see the arrow in FIG. 4B ). Therefore, the alignment direction of the first alignment film 134 and the alignment direction of the second alignment film 136 are perpendicular to each other. Here, the alignment direction refers to the long axis direction of the liquid crystal molecules when they are oriented by the influence of the alignment film. Note that instead of a rubbing treatment, the alignment directions of the first alignment film 134 and the second alignment film 136 may be formed by photo-alignment. Photo-alignment is a rubbing-less alignment treatment using light, for example, by irradiating polarized light in the ultraviolet region from a predetermined direction onto an alignment film that has not been subjected to a rubbing treatment. This causes a photoreaction in the alignment film, introducing anisotropy into the surface of the alignment film and imparting the ability to control the alignment of liquid crystals.

[0040] The liquid crystal layer 138 contains liquid crystal molecules. The structure of the liquid crystal molecules is not limited. Therefore, the liquid crystal molecules may be nematic liquid crystal, smectic liquid crystal, cholesteric liquid crystal, or chiral smectic liquid crystal.

[0041] Thickness T of the liquid crystal layer 138 LC (See FIG. 3), that is, the distance between the first alignment film 134 and the second alignment film 136 is also arbitrary, but the pitch P L , P U For example, the thickness T LC is the pitch P of the lower electrodes 130 or the upper electrodes 132 L , P UIt is preferable to set the thickness to 2 to 10 times, 2 to 5 times, or 2 to 3 times the thickness of the liquid crystal layer 138. A specific thickness of the liquid crystal layer 138 may be selected, for example, from the range of 10 μm to 60 μm or 10 μm to 50 μm. Although not shown, spacers may be provided in the liquid crystal layer 138 to maintain this thickness throughout the entire lighting device 100. Note that if the above-described thickness of the liquid crystal layer 138 is adopted in a liquid crystal display device, the high responsiveness required for displaying moving images cannot be obtained, and it becomes extremely difficult to demonstrate the functions of the liquid crystal display device.

[0042] 2-4.Other configurations As shown in Fig. 4A, the lower electrode 130 is connected to a drive circuit 116 provided on the substrate 122 via wiring 144. The drive circuit 116 is further connected to a plurality of terminals 118, and a signal for driving the lighting device 100 is supplied to the drive circuit 116 from an external circuit (not shown) via the terminal 118. The drive circuit 116 supplies a voltage to the lower electrode 130 based on this signal. The wiring 146 is connected to wiring (not shown) on the substrate 122 via contacts 148 (see Fig. 4B). This wiring is also connected to the drive circuit 116, and the drive circuit 116 also supplies a voltage to the upper electrode 132 based on the signal supplied from the external circuit via the terminal 118.

[0043] The driving circuit 116 may be formed by appropriately combining various conductive films, semiconductor films, and conductive films patterned on the substrate 122, or may be formed by mounting an IC chip having an integrated circuit formed on a semiconductor substrate on the substrate 122. Alternatively, the driving circuit 116 may not be provided on the substrate 122, but an IC chip may be provided as the driving circuit 116 on a flexible printed circuit (FPC) connected to the terminals 118.

[0044] 3. Operating Principle The driving principle of the lighting device 100 will be explained using the schematic perspective view of Fig. 7. Here, in order to show the behavior of the liquid crystal molecules indicated by the ellipses, the lower electrode 130 and the upper electrode 132 are indicated by dotted lines, and other components are omitted.

[0045] When the liquid crystal panel 120 is driven, a pulsed AC voltage is applied to the plurality of lower electrodes 130 so that the phase is inverted between adjacent lower electrodes 130. Similarly, a pulsed AC voltage is applied to the plurality of upper electrodes 132 so that the phase is inverted between adjacent upper electrodes 132. The frequency of these AC voltages is the same in each liquid crystal panel 120. The AC voltage may be selected, for example, from the range of 3 V to 50 V or from 3 V to 30 V. Since the extension directions of the lower electrodes 130 and the upper electrodes 132 are orthogonal to each other, application of the AC voltage generates electric fields (horizontal electric fields) that are orthogonal to each other between adjacent lower electrodes 130 and between adjacent upper electrodes 132 (see the curved arrows in Figure 7). Note that an electric field (vertical electric field) is also generated between the lower electrodes 130 and the upper electrodes 132, but the electric field is generated by the thickness T of the liquid crystal layer 138. CL is the distance S between adjacent lower electrodes 130 or upper electrodes 132. L , S U Therefore, the vertical electric field is significantly smaller than the horizontal electric field and can be ignored, so that the liquid crystal molecules are oriented according to the horizontal electric field.

[0046] When a transverse electric field is generated in the liquid crystal layer 138, the liquid crystal molecules on the substrate 122 side are aligned in an upwardly convex arc shape. Similarly, on the counter substrate 124 side, the liquid crystal molecules are aligned in a downwardly convex arc shape (FIG. 7). This change in the alignment of the liquid crystal molecules generates a refractive index distribution, and as a result, of the light incident on the liquid crystal layer 138 from the lower electrode 130 side of the first liquid crystal panel 120-1, a component (polarized component) 150 parallel to the transverse electric field formed by the lower electrode 130 is diffused. Furthermore, the alignment direction of the liquid crystal molecules rotates and twists 90° around the z-direction as it approaches the counter substrate 124 from the substrate 122. As a result, the diffused component 150 is rotated by 90° as it passes through the liquid crystal layer 138. The diffused and rotated component 150 is further diffused in accordance with the refractive index distribution of the arc-shaped aligned liquid crystal molecules on the counter substrate 124 side, giving a component (polarized component) 152. On the other hand, component 156 (polarized component) orthogonal to component 150 is not diffused because its polarization axis is perpendicular to the transverse electric field formed by lower electrode 130 of first liquid crystal panel 120-1, and is rotated by 90° within liquid crystal layer 138. The polarization axis of rotated component 156 is also perpendicular to the direction of the transverse electric field on the counter substrate 124 side, so it is not diffused, and simply provides component 158 ​​(polarized component) whose polarization axis is rotated by 90°. In this way, first liquid crystal panel 120-1 functions as a lens that diffuses one component of the incident light (component 150 in this case).

[0047] A similar principle also applies to the second liquid crystal panel 120-2. Although details will be omitted, the second liquid crystal panel 120-2 rotates and diffuses component 158, and rotates component 152 without diffusing it. In other words, the second liquid crystal panel 120-2 functions as a lens that diffuses component 156 that was not diffused by the first liquid crystal panel 120-1. In summary, the first liquid crystal panel 120-1 and the second liquid crystal panel 120-2 can diffuse all components of the incident light.

[0048] When the liquid crystal panel 120 is not driven, no transverse electric field is generated. Therefore, when the liquid crystal panel 120 is not driven, the liquid crystal molecules are aligned according to the alignment directions of the first alignment film 134 and the second alignment film 136. Therefore, the alignment direction of the liquid crystal molecules is the alignment direction of the first alignment film 134 (i.e., a direction perpendicular to the extension direction of the lower electrode 130) near the substrate 122, and as they approach the opposing substrate 124, they rotate around the z direction as a central axis and are twisted 90°. As a result, the highly directional collimated light emitted from the light source 110 is only optically rotated without being diffused when the liquid crystal panel 120 is not driven, and therefore, a relatively narrow range can be selectively illuminated (FIG. 8A). On the other hand, when the liquid crystal panel 120 is driven, the light from the light source 110 is diffused, providing an illumination surface 164 having a larger area than the illumination surface 162 provided by the lighting device 100 when the liquid crystal panel 120 is not driven (FIG. 8B). Furthermore, since the degree of diffusion depends on the strength of the transverse electric field, it is possible to control the diffusion of light from the light source 110 by adjusting the potentials applied to the lower electrode 130 and the upper electrode 132. Therefore, the lighting device 100 functions as a lighting device whose illumination range can be arbitrarily controlled.

[0049] However, when the plurality of lower electrodes 130 and upper electrodes 132 are arranged with high regularity, periodicity occurs in the refractive index distribution of the liquid crystal. L , W U , interval S L , S U , and pitch P L , P U If the lower electrodes 130 and upper electrodes 132 are arranged so that the refractive index is constant within each lower electrode group 140 or each upper electrode group 142, periodicity occurs in the refractive index distribution of the liquid crystal when the liquid crystal panel 120 is driven. As a result, interference fringes (moiré) occur on the irradiation surface 164. Furthermore, even when a light emitting element 114 that emits white light is used, the light is colored due to the periodic refractive index distribution. Although the occurrence of moiré can be suppressed by placing a diffusion sheet above or below the liquid crystal panel 120, the light is diffused even when the liquid crystal panel 120 is not driven, causing the irradiation surface 162 to unintentionally expand.

[0050] On the other hand, in the lighting device 100, as described above, the intervals SL , width W L , and pitch P L Similarly, in each upper electrode group 142, the spacing S U , width W U , and pitch P U Therefore, as will be shown in the examples described later, the periodicity of the refractive index distribution of the liquid crystal is significantly reduced, and as a result, the occurrence of moire and coloring of light can be effectively suppressed without using a diffusion sheet. Furthermore, since a diffusion sheet is not required, diffusion of light can also be avoided when the liquid crystal panel 120 is not driven.

[0051] In this way, by applying one of the embodiments of the present invention, it is possible to provide a lighting device that can prevent the occurrence of moire and coloring of light and that can arbitrarily control the illumination range.

[0052] Second Embodiment This embodiment describes a modification of the lighting device 100 described in the first embodiment. Configurations that are the same as or similar to those described in the first embodiment may be omitted.

[0053] In this modification, as shown in the schematic top views of FIGS. 9A and 9B, the lower electrode 130 and the upper electrode 132 are arranged so as to be inclined. More specifically, the direction in which the lower electrode 130 extends differs between the first liquid crystal panel 120-1 and the second liquid crystal panel 120-2. Similarly, the direction in which the upper electrode 132 extends differs between the first liquid crystal panel 120-1 and the second liquid crystal panel 120-2. The angle (first angle) formed between the direction in which the lower electrode 130 of the first liquid crystal panel 120-1 extends and the direction in which the lower electrode 130 of the second liquid crystal panel 120-2 extends may be greater than 0° and equal to or less than 5° or equal to or less than 3°. In this embodiment, the first angle is set to 2°, so that the direction in which the lower electrode 130 of the first liquid crystal panel 120-1 extends is inclined at −1° with respect to the x-direction, and the direction in which the lower electrode 130 of the second liquid crystal panel 120-2 extends is inclined at +1° with respect to the x-direction. Since the lower electrode 130 and the upper electrode 132 of each liquid crystal panel 120 are perpendicular to each other, the angle formed between the direction in which the upper electrode 132 of the first liquid crystal panel 120-1 extends and the direction in which the upper electrode 132 of the second liquid crystal panel 120-2 extends is also the first angle. Note that if the substrate 122 and the counter substrate 124 are rectangular, at least one of the lower electrode 130 and the upper electrode 132 of each liquid crystal panel 120 is inclined with respect to one of the sides of the substrate 122 and the counter substrate 124.

[0054] In this way, by configuring the lighting device 100 so that the extension directions of the upper electrodes 132 between the two liquid crystal panels 120 are shifted from each other and the extension directions of the lower electrodes 130 are shifted from each other, the periodicity of the refractive index distribution of the liquid crystal is significantly reduced, and the occurrence of moire can be more effectively suppressed.

[0055] <Third embodiment> In this embodiment, a lighting device 170 having a different structure from the lighting device 100 will be described. Configurations that are the same as or similar to those described in the first and second embodiments may be omitted. One difference between the lighting device 170 and the lighting device 100 is that, in addition to the first liquid crystal panel 120-1 and the second liquid crystal panel 120-2, the lighting device 170 further includes a third liquid crystal panel 120-3 and a fourth liquid crystal panel 120-4 having the same configuration as the first and second liquid crystal panels 120-1 and 120-2 (FIG. 10). The third liquid crystal panel 120-3 is disposed between the second liquid crystal panel 120-2 and the fourth liquid crystal panel 120-4.

[0056] Between the third liquid crystal panel 120-3 and the fourth liquid crystal panel 120-4, the extension directions of the lower electrodes 130 are parallel to each other, and the extension directions of the upper electrodes 132 are also parallel to each other. However, the extension direction of the lower electrodes 130 of the third liquid crystal panel 120-3 and the fourth liquid crystal panel 120-4 is perpendicular to the extension direction of the lower electrodes 130 of the first liquid crystal panel 120-1 and the second liquid crystal panel 120-2. Similarly, the extension direction of the upper electrodes 132 of the third liquid crystal panel 120-3 and the fourth liquid crystal panel 120-4 is perpendicular to the extension direction of the upper electrodes 132 of the first liquid crystal panel 120-1 and the second liquid crystal panel 120-2. For example, if the extension directions of the lower electrode 130 and the upper electrode 132 in the first liquid crystal panel 120-1 and the second liquid crystal panel 120-2 are the x-direction and the y-direction, respectively (FIGS. 4A and 4B), the extension directions of the lower electrode 130 and the upper electrode 132 in the third liquid crystal panel 120-3 and the fourth liquid crystal panel 120-4 are the y-direction and the x-direction, respectively (FIGS. 11A and 11B). Furthermore, the alignment direction of the first alignment film 134 in the third liquid crystal panel 120-3 and the fourth liquid crystal panel 120-4 (see the hollow arrows in FIG. 11A) is also perpendicular to that of the first alignment film 134 in the first liquid crystal panel 120-1 and the second liquid crystal panel 120-2 (see the hollow arrows in FIG. 4A). In addition, the alignment direction of the second alignment film 136 of the third liquid crystal panel 120-3 and the fourth liquid crystal panel 120-4 (see the white arrows in Figure 11B) is also perpendicular to that of the second alignment film 136 of the first liquid crystal panel 120-1 and the second liquid crystal panel 120-2 (see the white arrows in Figure 4B).

[0057] By stacking four liquid crystal panels 120 in this way, it is possible to provide a lighting device that can further diffuse light compared to the lighting device 100 in which two liquid crystal panels 120 are stacked, and therefore can irradiate a wider range. Also, although a detailed description will be omitted, the third liquid crystal panel 120-3 and the fourth liquid crystal panel 120-4 also have a spacing S between the lower electrodes 130 in each lower electrode group 140. L , the width W of the lower electrode 130 L , and the pitch P of the lower electrodes 130 L In each upper electrode group 142, the spacing S between the upper electrodes 132 is varied. U , the width W of the upper electrode 132 U , and the pitch P of the upper electrodes 132 L Therefore, it is possible to effectively suppress the occurrence of moire and coloring of light, and also to arbitrarily control the irradiation range.

[0058] 12A is a schematic diagram showing a case where one bottom electrode 130 selected from each of the first liquid crystal panel 120-1 to the fourth liquid crystal panel 120-4 is moved in parallel in the x and y directions and stacked in the z direction. As in the modification of the second embodiment, the extension direction V of the bottom electrodes 130 of the first liquid crystal panel 120-1 and the second liquid crystal panel 120-2 is L1 and V L2 The illumination device 170 may be configured so that the angle formed by the first angle θ1 (see FIG. 12B) is the first angle θ1. Furthermore, in the illumination device 170, the lower electrodes 130 of the third liquid crystal panel 120-3 and the fourth liquid crystal panel 120-4 are also aligned in the extension direction V L3 and V L4 The drawing direction V may be shifted. L3 and V L4If the angle formed by these is defined as a second angle θ2 (see FIGS. 12A and 12C), the first angle θ1 and the second angle θ2 may be the same or different. In the latter case, the second angle θ2 may be larger than the first angle θ1. For example, the second angle θ2 can be selected from a range greater than 0° and equal to or less than 10°. Although not explained further, the same applies to the upper electrodes 132 that are perpendicular to the lower electrodes 130 in each liquid crystal panel 120. In this embodiment, the first angle θ1 is set to 2°, so that the extension direction of the lower electrodes 130 of the first liquid crystal panel 120-1 is inclined by −1° with respect to the x-direction, and the extension direction of the lower electrodes 130 of the second liquid crystal panel 120-2 is inclined by +1° with respect to the x-direction. In addition, the second angle θ1 is set to 6°, the direction in which the lower electrode 130 of the third liquid crystal panel 120-3 extends is inclined at -3° with respect to the y direction, and the direction in which the lower electrode 130 of the fourth liquid crystal panel 120-4 extends is inclined at +3° with respect to the y direction.

[0059] In this way, by shifting the extension directions of the lower electrode 130 and the upper electrode 132 between the third liquid crystal panel 120-3 and the fourth liquid crystal panel 120-4, moire can be more effectively prevented. Here, for these four liquid crystal panels, the first liquid crystal panel 120-1 and the second liquid crystal panel 120-2 primarily rotate and diffuse the polarized light components that intersect with each other. Furthermore, the third liquid crystal panel 120-3 and the fourth liquid crystal panel 120-4 additionally rotate and diffuse the diffused polarized light components, reducing coloring and improving diffusion. Considering these points, since the first angle θ1 affects the initial rotation and diffusion of the incident light, setting the first angle θ1 to a large angle results in insufficient rotation and diffusion, resulting in a deterioration in the quality of the emitted light. On the other hand, setting the second angle θ2 to a certain value increases the diffusivity of the emitted light. Taking these points into consideration, by making the second angle θ2 larger than the first angle θ1 and setting the second angle θ2 to 0° to 10°, more preferably 3° to 7°, it is possible to improve diffusion and suppress coloring while maintaining the quality of the emitted light.

[0060] <Fourth embodiment> In this embodiment, an illumination device 180 having a different configuration from the illumination devices 100 and 170 will be described. Descriptions of configurations that are the same as or similar to those described in the first to third embodiments may be omitted. Like the illumination device 170, the illumination device 180 has first to fourth liquid crystal panels 120-4 stacked in order on the light source 110, but one of the differences from the illumination device 170 is that in each liquid crystal panel 120, one of the lower electrode 130 and the upper electrode 132 is composed of a single electrode.

[0061] FIG. 13 is a schematic perspective view of the lighting device 180. For clarity, only a portion of the lower electrodes 130 and upper electrodes 132 of each liquid crystal panel 120 is shown. As shown in FIG. 13, in the lighting device 180, the lower electrodes 130 of each of the first liquid crystal panel 120-1 and the second liquid crystal panel 120-2 are each composed of a single lower electrode 130. In each of the first liquid crystal panel 120-1 and the second liquid crystal panel 120-2, the single lower electrode 130 may overlap all of the upper electrodes 132. Meanwhile, in each of the third liquid crystal panel 120-3 and the fourth liquid crystal panel 120-4, the upper electrodes 132 are each composed of a single upper electrode 132. In each of the third liquid crystal panel 120-3 and the fourth liquid crystal panel 120-4, the single upper electrode 132 may also overlap all of the lower electrodes 130.

[0062] Even in this configuration, in the first liquid crystal panel 120-1 and the second liquid crystal panel 120-2, no refractive index distribution occurs on the lower electrode 130 side of the liquid crystal layer 138, but a refractive index distribution occurs on the upper electrode 132 side. Therefore, as shown in Fig. 13, one component of the incident light (e.g., the S-polarized component) is diffused by the first liquid crystal panel 120-1, and the other component (the P-polarized component) is diffused by the second liquid crystal panel 120-2. Similarly, in the third liquid crystal panel 120-3 and the fourth liquid crystal panel 120-4, no refractive index distribution occurs on the upper electrode 132 side of the liquid crystal layer 138, but a refractive index distribution occurs on the lower electrode 130 side. Therefore, one component of the incident light (the P-polarized component) is diffused by the third liquid crystal panel 120-3, and the other component (the S-polarized component) is diffused by the fourth liquid crystal panel 120-4.

[0063] 14, the upper electrodes 132 of the first liquid crystal panel 120-1 and the second liquid crystal panel 120-2 may each be configured with a single upper electrode 132, and the lower electrodes 130 of the third liquid crystal panel 120-3 and the fourth liquid crystal panel 120-4 may each be configured with a single lower electrode 130. Even in this case, the single upper electrode 132 may overlap all of the lower electrodes 130 in each of the first liquid crystal panel 120-1 and the second liquid crystal panel 120-2, and the single lower electrode 130 may overlap all of the upper electrodes 132 in each of the third liquid crystal panel 120-3 and the fourth liquid crystal panel 120-4. Even with this configuration, as shown in FIG. 14, light diffusion similar to that of the configuration shown in FIG. 13 occurs.

[0064] 15, the first liquid crystal panel 120-1 and the second liquid crystal panel 120-2 may not have the upper electrode 132, and the third liquid crystal panel 120-3 and the fourth liquid crystal panel 120-4 may not have the lower electrode 130. In this case, the second alignment film 136 may be in direct contact with the counter substrate 124 in the first liquid crystal panel 120-1 and the second liquid crystal panel 120-2. Furthermore, the first alignment film 134 may be in direct contact with the substrate 122 in the third liquid crystal panel 120-3 and the fourth liquid crystal panel 120-4.

[0065] 16, the first liquid crystal panel 120-1 and the second liquid crystal panel 120-2 may not have the lower electrode 130, and the third liquid crystal panel 120-3 and the fourth liquid crystal panel 120-4 may not have the upper electrode 132. In this case, the first alignment film 134 may be in direct contact with the substrate 122 in the first liquid crystal panel 120-1 and the second liquid crystal panel 120-2, and the second alignment film 136 may be in direct contact with the opposing substrate 124 in the third liquid crystal panel 120-3 and the fourth liquid crystal panel 120-4.

[0066] 15 and 16, in each liquid crystal panel 120, a refractive index distribution can be generated on the lower electrode 130 side or the upper electrode 132 side of the liquid crystal layer 138, so that both components of the incident light can be diffused, similar to the lighting device 170. Furthermore, in each liquid crystal panel 120, it is only necessary to drive the lower electrode 130 or the upper electrode 132 side, so that the thickness T LC This reduces the number of electrodes through which light from the light source 110 passes, thereby improving the light transmittance of each liquid crystal panel 120. Furthermore, since the number of electrodes can be reduced, it becomes possible to provide a lighting device in a shorter time and at a lower cost.

[0067] Although details are omitted, similarly to the illumination device 100, the illumination device 180 also has a plurality of lower electrodes 130 arranged at intervals S L , width W L , and pitch P L The upper electrodes 132 are also arranged at intervals S U , width W U , and pitch P U Therefore, coloring of light is prevented, and at the same time, moire can be prevented without using a diffusion sheet. [Example]

[0068] In this example, the results are presented that preliminarily prove that the occurrence of moire and coloring can be suppressed by varying the spacing, width, or pitch of the lower electrodes 130 and upper electrodes 132 in the lighting device 100.

[0069] 1. Experiment A first liquid crystal panel 120-1 shown in FIG. 14 was fabricated as a liquid crystal panel. Specifically, a total of 250 lower electrodes (length: 40 mm, thickness: 77 nm) containing ITO arranged in stripes were fabricated by sputtering on a 5 cm x 5 cm glass substrate provided with an undercoat (thickness: 200 nm) containing silicon oxide. A 5 cm x 5 cm glass substrate provided with an overcoat (thickness: 200 nm) containing silicon oxide was used as the counter substrate. A single ITO electrode (40 mm x 40 mm, thickness: 77 nm) overlapping the lower electrode was formed on the overcoat of the counter substrate by sputtering as the upper electrode. The substrate and the counter substrate were fixed using a sealant containing a photocurable resin, and a TN liquid crystal layer was placed between them. A total of five liquid crystal panels were fabricated by varying the width of the bottom electrodes in the liquid crystal panel from 5 μm to 11 μm, the spacing from 5 μm to 15 μm, and the pitch from 10 μm to 20 μm. The coefficients of variation for these liquid crystal panels are shown in Table 1. [Table 1]

[0070] An AC voltage of ±15V (frequency: 60Hz) was applied between adjacent lower electrodes of the fabricated liquid crystal panel so that the phase was reversed, and in this state, a white light source was irradiated onto the liquid crystal panel. The irradiated surface formed on a white paper as the light passed through the liquid crystal panel was observed.

[0071] 2. Results and Discussion Photographs of the illuminated surface are shown in Figures 17A to 17E. As shown in these figures, in the fabricated LCD panel, a transverse electric field is generated only on the bottom electrode side, so light is diffused in only one direction. However, it is still possible to verify the effect of variations in the spacing, width, and pitch of the bottom electrodes on coloration and moire generation.

[0072] As shown in Figure 17A, in the case of Panel No. 1, a comparative example in which the spacing, width, and pitch of the lower electrodes were consistent, light coloring was clearly observed, and moiré patterns were also clearly observed. In contrast, in Panel No. 2, in which the spacing and pitch were varied while the width was fixed (coefficient of variation: 0.00), slight coloring was observed, but moiré patterns were barely discernible. Furthermore, in Panels Nos. 3 to 5, in which the width, spacing, and pitch were all varied, neither coloring nor moiré patterns were observed. These results demonstrate that varying at least one of the width, spacing, and pitch of the multiple lower electrodes arranged in a stripe pattern can effectively suppress light coloring and moiré patterns. Although the effects of variations in the width, spacing, and pitch of the upper electrodes were not investigated in this example, it is easy to predict that similar results would be obtained.

[0073] The above-described embodiments of the present invention can be combined as appropriate as long as they are not mutually inconsistent. Furthermore, a display device in which a person skilled in the art appropriately adds or deletes components or modifies the design, or adds or omits processes or modifies conditions, based on the display device of each embodiment, is also included in the scope of the present invention as long as it includes the gist of the present invention.

[0074] Even if there are other effects and advantages different from those brought about by the aspects of each of the above-mentioned embodiments, those that are clear from the description in this specification or that can be easily predicted by a person skilled in the art are naturally understood to be brought about by the present invention. [Explanation of symbols]

[0075] 100: lighting device, 110: light source, 112: reflector, 112a: recess, 114: light emitting element, 116: drive circuit, 118: terminal, 120: liquid crystal panel, 120-1: first liquid crystal panel, 120-2: second liquid crystal panel, 120-3: third liquid crystal panel, 120-4: fourth liquid crystal panel, 122: substrate, 124: opposing substrate, 126: undercoat, 128: overcoat, 130: lower electrode, 130-1: lower electrode, 130-2: lower electrode, 130a: lower electrode, 130b: lower electrode, 130c: lower electrode, 13 2: upper electrode, 132-1: upper electrode, 132-2: upper electrode, 132a: upper electrode, 132b: upper electrode, 132c: upper electrode, 134: first alignment film, 136: second alignment film, 138: liquid crystal layer, 140: lower electrode group, 142: upper electrode group, 144: wiring, 144-1: wiring, 144-2: wiring, 146: wiring, 146-1: wiring, 146-2: wiring, 148: contact, 150: component, 152: component, 156: component, 158: component, 162: irradiation surface, 164: irradiation surface, 170: lighting device, 180: lighting device

Claims

1. The display device includes first to fourth liquid crystal panels stacked in order from the light-entering side to the light-emitting side, Each of the first liquid crystal panel and the second liquid crystal panel comprises: substrate, a plurality of lower electrodes arranged in a stripe pattern on the substrate; a first alignment film disposed on the plurality of lower electrodes; a liquid crystal layer on the first alignment film; a second alignment film disposed on the liquid crystal layer, the second alignment film having an alignment direction perpendicular to that of the first alignment film; and a counter substrate on the second alignment film; Each of the third liquid crystal panel and the fourth liquid crystal panel comprises: substrate, a first alignment film on the substrate; a liquid crystal layer on the first alignment film; a second alignment film disposed on the liquid crystal layer, the second alignment film having an alignment direction perpendicular to that of the first alignment film; a plurality of upper electrodes arranged in a stripe pattern on the second alignment film; and a counter substrate on the plurality of upper electrodes; At least one of the third liquid crystal panel and the fourth liquid crystal panel further includes a single lower electrode between the substrate and the first alignment film, the lower electrode overlapping the plurality of upper electrodes; an optical element, wherein the plurality of lower electrodes of the first liquid crystal panel and the second liquid crystal panel extend in a direction perpendicular to a direction in which the plurality of upper electrodes of the third liquid crystal panel and the fourth liquid crystal panel extend;

2. In each of the first liquid crystal panel and the second liquid crystal panel, for first to third lower electrodes arbitrarily selected from the plurality of lower electrodes and arranged consecutively, a distance between the first lower electrode and the second lower electrode is different from a distance between the second lower electrode and the third lower electrode; 2. The optical element of claim 1, wherein in each of the third liquid crystal panel and the fourth liquid crystal panel, for first to third upper electrodes arranged consecutively and arbitrarily selected from the plurality of upper electrodes, the spacing between the first upper electrode and the second upper electrode is different from the spacing between the second upper electrode and the third upper electrode.

3. The display device includes first to fourth liquid crystal panels stacked in order from the light-entering side to the light-emitting side, Each of the first liquid crystal panel and the second liquid crystal panel comprises: substrate, a first alignment film disposed on the substrate; a liquid crystal layer on the first alignment film; a second alignment film disposed on the liquid crystal layer, the second alignment film having an alignment direction perpendicular to that of the first alignment film; a plurality of upper electrodes arranged in a stripe pattern on the second alignment film; and a counter substrate on the plurality of upper electrodes; At least one of the first liquid crystal panel and the second liquid crystal panel further includes a single lower electrode between the substrate and the first alignment film, the lower electrode overlapping the plurality of upper electrodes; Each of the third liquid crystal panel and the fourth liquid crystal panel comprises: substrate, a plurality of lower electrodes arranged in a stripe pattern on the substrate; a first alignment film disposed on the plurality of lower electrodes; a liquid crystal layer on the first alignment film; a second alignment film disposed on the liquid crystal layer, the second alignment film having an alignment direction perpendicular to that of the first alignment film; and a counter substrate on the second alignment film; an extension direction of the plurality of upper electrodes of the first liquid crystal panel and the second liquid crystal panel perpendicular to an extension direction of the plurality of lower electrodes of the third liquid crystal panel and the fourth liquid crystal panel;

4. In each of the first liquid crystal panel and the second liquid crystal panel, for first to third upper electrodes arbitrarily selected from the plurality of upper electrodes and arranged consecutively, a distance between the first upper electrode and the second upper electrode is different from a distance between the second upper electrode and the third upper electrode; 4. The optical element of claim 3, wherein in each of the third liquid crystal panel and the fourth liquid crystal panel, for first to third lower electrodes arranged consecutively and arbitrarily selected from the plurality of lower electrodes, the spacing between the first lower electrode and the second lower electrode is different from the spacing between the second lower electrode and the third lower electrode.

5. The optical element according to claim 1 or 3, and an illumination device having a light source disposed on the light-entering side of the first liquid crystal panel;

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