Optical Elements

Abstract

An optical element (10) according to the present invention includes at least four liquid crystal cells (100-1, 100-2, 100-3, 100-4) which are sequentially stacked. The at least four liquid crystal cells (100-1, 100-2, 100-3, 100-4) each include: a first substrate (110-1) in which a first transparent electrode (120-1) and a second transparent electrode (120-2) extend in a first direction and are disposed alternatingly in a second direction crossing the first direction; a second substrate (110-2) in which a third transparent electrode (120-3) and a fourth transparent electrode (120-4) extend in the second direction and are disposed alternatingly in the first direction; and a liquid crystal layer (150) disposed between the first substrate (110-1) and the second substrate (110-2).

Description

[Technical field]

[0001] An embodiment of the present invention relates to an optical element that controls the distribution of light emitted from a light source. [Background technology]

[0002] Conventionally, optical elements that utilize the change in refractive index of liquid crystals by adjusting the voltage applied to the liquid crystal, so-called liquid crystal lenses, have been known (see, for example, Patent Document 1, Patent Document 2, or Patent Document 3). For example, the lighting devices described in Patent Document 1 and Patent Document 2 use a liquid crystal lens to distribute light from a light source in a circular shape. In addition, the beam shaping device described in Patent Document 3 changes the light distribution shape by changing the pattern of electrodes applied to the liquid crystal. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2005-317879 A [Patent Document 2] JP 2010-230887 A [Patent Document 3] JP 2014-160277 A Summary of the Invention [Problem to be solved by the invention]

[0004] Optical elements that include liquid crystal cells have problems such as uneven brightness, coloring, and moire, which can cause degradation of light distribution characteristics, depending on the configuration of the liquid crystal cell. For this reason, an optical element that can provide a uniform light distribution has been desired.

[0005] In view of the above problems, an object of one embodiment of the present invention is to provide an optical element that can provide a uniform light distribution. [Means for solving the problem]

[0006] An optical element according to one embodiment of the present invention includes at least four liquid crystal cells stacked in sequence, each of the at least four liquid crystal cells including a first substrate having first transparent electrodes and second transparent electrodes extending in a first direction and alternately arranged in a second direction intersecting the first direction, a second substrate having third transparent electrodes and fourth transparent electrodes extending in the second direction and alternately arranged in the first direction, and a liquid crystal layer between the first substrate and the second substrate.

[0007] An optical element according to one embodiment of the present invention includes a first liquid crystal cell, a second liquid crystal cell, a third liquid crystal cell, and a fourth liquid crystal cell stacked in sequence, and 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 first substrate on which first transparent electrodes and second transparent electrodes extending in a direction having a first angle with respect to the first direction are alternately arranged in a second direction perpendicular to the first direction, a second substrate on which third transparent electrodes and fourth transparent electrodes extending in a direction having a second angle with respect to the second direction are alternately arranged in the first direction, and a liquid crystal layer between the first substrate and the second substrate.

[0008] An optical element according to an embodiment of the present invention 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 stacked, 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 first transparent electrode which extends in a direction having a first angle with respect to a first direction and is bent in a direction having a second angle with respect to the first direction, and a second liquid crystal cell which extends in a direction having a second angle with respect to the first direction and is bent in a direction having the first angle with respect to the first direction. The liquid crystal display device includes a first substrate on which bent second transparent electrodes are alternately arranged in a second direction perpendicular to the first direction, a second substrate on which third transparent electrodes extend in a direction having a third angle with respect to the second direction and bend in a direction having a fourth angle with respect to the second direction, and a fourth transparent electrode extend in a direction having a fourth angle with respect to the second direction and bend in a direction having the third angle with respect to the second direction, and a liquid crystal layer between the first substrate and the second substrate. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic perspective view of an optical element according to one embodiment of the present invention. [Figure 2A] 1 is a schematic cross-sectional view of an optical element according to one embodiment of the present invention. [Figure 2B] 1 is a schematic cross-sectional view of an optical element according to one embodiment of the present invention. [Figure 3A] 2 is a schematic cross-sectional view illustrating the alignment direction of liquid crystal molecules in a liquid crystal layer of a liquid crystal cell of an optical element according to one embodiment of the present invention and the properties of light passing through the liquid crystal cell. FIG. [Figure 3B] 2 is a schematic cross-sectional view illustrating the alignment direction of liquid crystal molecules in a liquid crystal layer of a liquid crystal cell of an optical element according to one embodiment of the present invention and the properties of light passing through the liquid crystal cell. FIG. [Figure 4] 1 is a graph showing the transmittance of an optical element according to an embodiment of the present invention and a conventional optical element. [Diagram 5] FIG. 2 is a schematic diagram illustrating the configuration of a transparent electrode of a liquid crystal cell of the optical element according to one embodiment of the present invention. [Figure 6] FIG. 2 is a schematic diagram illustrating the configuration of a transparent electrode of a liquid crystal cell of the optical element according to one embodiment of the present invention. [Figure 7] FIG. 2 is a schematic diagram illustrating the configuration of a transparent electrode of a liquid crystal cell of the optical element according to one embodiment of the present invention. [Figure 8] FIG. 2 is a schematic diagram illustrating the configurations of a first electrode pattern and a second electrode pattern of a liquid crystal cell of an optical element according to one embodiment of the present invention. [Figure 9] FIG. 2 is a schematic diagram illustrating the configuration of a transparent electrode of a liquid crystal cell of the optical element according to one embodiment of the present invention. [Figure 10] FIG. 2 is a schematic diagram illustrating the configuration of a transparent electrode of a liquid crystal cell of the optical element according to one embodiment of the present invention. [Figure 11] FIG. 2 is a schematic diagram illustrating the configuration of a transparent electrode of a liquid crystal cell of the optical element according to one embodiment of the present invention. [Figure 12]FIG. 2 is a schematic diagram illustrating the configurations of a first electrode pattern and a second electrode pattern of a liquid crystal cell of an optical element according to one embodiment of the present invention. [Figure 13] FIG. 2 is a schematic diagram illustrating the configuration of a transparent electrode of a liquid crystal cell of the optical element according to one embodiment of the present invention. [Figure 14] FIG. 2 is a schematic diagram illustrating the configuration of a transparent electrode of a liquid crystal cell of the optical element according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, each embodiment 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 gist of the technical idea thereof, and should not be interpreted as being limited to the description of the embodiments exemplified below.

[0011] In order to clarify the description, the drawings may show the width, thickness, shape, etc. of each part in a schematic manner compared to the actual embodiment, but these are merely examples, and the illustrated shapes themselves do not limit the interpretation of the present invention. In addition, in the drawings, elements having the same functions as those explained in the drawings already shown in the specification may be given the same reference numerals even in different drawings, and duplicate explanations may be omitted.

[0012] When a film is processed to form multiple structures, each structure may have a different function or role, and each structure may be formed on a different base. However, these multiple structures are derived from a film formed as the same layer in the same process, and have the same material. Therefore, these multiple films are defined as existing in the same layer.

[0013] When expressing an aspect in which a structure is placed on top of another structure, the term "above" is used, unless otherwise specified, to include both a case in which another structure is placed directly above, in contact with, a structure, and a case in which another structure is placed above, via yet another structure.

[0014] An optical element 10 according to one embodiment of the present invention will be described with reference to FIGS.

[0015] [1. Configuration of optical element 10] FIG. 1 is a schematic perspective view of an optical element 10 according to an embodiment of the present invention. As shown in FIG. 1, the optical element 10 includes a plurality of liquid crystal cells 100 (a first liquid crystal cell 100-1, a second liquid crystal cell 100-2, a third liquid crystal cell 100-3, and a fourth liquid crystal cell 100-4) stacked in the z-axis direction. Although not shown, a light source is disposed above the first liquid crystal cell 100-1. In other words, the optical element 10 has a structure in which the first liquid crystal cell 100-1, the second liquid crystal cell 100-2, the third liquid crystal cell 100-3, and the fourth liquid crystal cell 100-4 are stacked in order based on the light source side. Therefore, the light emitted from the light source is transmitted through the first liquid crystal cell 100-1, the second liquid crystal cell 100-2, the third liquid crystal cell 100-3, and the fourth liquid crystal cell 100-4 in order.

[0016] Two adjacent liquid crystal cells 100 of the plurality of liquid crystal cells 100 are bonded together via an optical elastic resin layer 160. As the optical elastic resin layer 160, for example, an adhesive containing an acrylic resin or an epoxy resin having light transmission properties can be used.

[0017] The optical element 10 includes at least two liquid crystal cells 100, and thus can control the light distribution of unpolarized light. Therefore, the optical element 10 does not need to include, for example, a pair of polarizing plates provided on the front and back surfaces of the liquid crystal display element. Although four liquid crystal cells 100 are shown in FIG. 1, the number of liquid crystal cells 100 included in the optical element 10 is not limited to this. The number of liquid crystal cells included in the optical element 10 may be five or more.

[0018] 2A and 2B are schematic cross-sectional views of an optical element 10 according to an embodiment of the present invention. Specifically, FIG. 2A is a schematic cross-sectional view in a zx plane cut along line A1-A2 shown in FIG. 1, and FIG. 2B is a schematic cross-sectional view in a yz plane cut along line B1-B2 shown in FIG. 1. In the following, the x-axis direction and the y-axis direction may be referred to as a first direction and a second direction, respectively. That is, the second direction is a direction perpendicular to the first direction.

[0019] 2A and 2B, each of the liquid crystal cells 100 includes a first substrate 110-1, a second substrate 110-2, a first transparent electrode 120-1, a second transparent electrode 120-2, a third transparent electrode 120-3, a fourth transparent electrode 120-4, a first alignment film 130-1, a second alignment film 130-2, a sealant 140, and a liquid crystal layer 150. On the first substrate 110-1, the first transparent electrode 120-1, the second transparent electrode 120-2, and a first alignment film 130-1 covering the first transparent electrode 120-1 and the second transparent electrode 120-2 are provided. In addition, on the second substrate 110-2, a third transparent electrode 120-3, a fourth transparent electrode 120-4, and a second alignment film 130-2 covering the third transparent electrode 120-3 and the fourth transparent electrode 120-4 are provided. The first substrate 110-1 and the second substrate 110-2 are arranged so that the first transparent electrode 120-1 and the second transparent electrode 120-2 on the first substrate 110-1 face the third transparent electrode 120-3 and the fourth transparent electrode 120-4 on the second substrate 110-2. In addition, the first substrate 110-1 and the second substrate 110-2 are bonded via a sealant 140 provided on the periphery of the first substrate 110-1 and the second substrate 110-2. Furthermore, liquid crystal is sealed in the space surrounded by the first substrate 110-1 (more specifically, the first alignment film 130-1), the second substrate 110-2 (more specifically, the second alignment film 130-2), and the sealing material 140, and a liquid crystal layer 150 is provided between the first substrate 110-1 and the second substrate 110-2.

[0020] Each of the first substrate 110-1 and the second substrate 110-2 may be a rigid substrate having light transmission properties, such as a glass substrate, a quartz substrate, a sapphire substrate, etc. Also, each of the first substrate 110-1 and the second substrate 110-2 may be a flexible substrate having light transmission properties, such as a polyimide resin substrate, an acrylic resin substrate, a siloxane resin substrate, a fluororesin substrate, etc.

[0021] Each of the first transparent electrode 120-1, the second transparent electrode 120-2, the third transparent electrode 120-3, and the fourth transparent electrode 120-4 functions as an electrode for forming an electric field in the liquid crystal layer 150. Each of the first transparent electrode 120-1, the second transparent electrode 120-2, the third transparent electrode 120-3, and the fourth transparent electrode 120-4 is made of a transparent conductive material such as indium tin oxide (ITO) or indium zinc oxide (IZO).

[0022] The liquid crystal layer 150 can refract the light passing therethrough or change the polarization state of the light passing therethrough depending on the orientation state of the liquid crystal molecules. Nematic liquid crystal or the like is used as the liquid crystal of the liquid crystal layer 150. The liquid crystal described in this embodiment is of the positive type, but it is also possible to apply a negative type by changing the orientation direction of the liquid crystal molecules when no voltage is applied to the transparent electrode 120. In addition, the liquid crystal preferably contains a chiral agent that imparts a twist to the liquid crystal molecules.

[0023] Each of the first alignment film 130-1 and the second alignment film 130-2 aligns the liquid crystal molecules in the liquid crystal layer 150 in a predetermined direction. A polyimide resin or the like is used as each of the first alignment film 130-1 and the second alignment film 130-2. Each of the first alignment film 130-1 and the second alignment film 130-2 may be given an alignment characteristic by an alignment treatment such as a rubbing method or a photo-alignment method. The rubbing method is a method of rubbing the surface of the alignment film in one direction. The photo-alignment method is a method of irradiating the alignment film with linearly polarized ultraviolet light.

[0024] An adhesive material containing epoxy resin or acrylic resin is used as the seal material 140. The adhesive material may be an ultraviolet curing type or a heat curing type.

[0025] Here, the extending direction of the transparent electrode 120 and the alignment characteristics of the alignment film 130 will be described.

[0026] In each of the first liquid crystal cell 100-1, the second liquid crystal cell 100-2, the third liquid crystal cell 100-3, and the fourth liquid crystal cell 100-4, the first transparent electrode 120-1 and the second transparent electrode 120-2 each include a plurality of comb-tooth portions extending in the x-axis direction and a connection portion extending in the y-axis direction to connect these comb-tooth portions, and the third transparent electrode 120-3 and the fourth transparent electrode 120-4 each include a plurality of comb-tooth portions extending in the y-axis direction and a connection portion extending in the x-axis direction to connect these comb-tooth portions. Note that, for convenience, in the following, the description of the transparent electrode 120 may be a description of the comb-tooth portions (a description of the transparent electrode 120 excluding the connection portion) in some cases. For example, when the extension direction of the comb-tooth portions of the first transparent electrode 120-1 is the x-axis direction, the extension direction of the first transparent electrode 120-1 may be the x-axis direction.

[0027] Therefore, the extension direction of each of the first transparent electrode 120-1 and the second transparent electrode is the x-axis direction, and the extension direction of each of the third transparent electrode 120-3 and the fourth transparent electrode 120-4 is the y-axis direction. The first transparent electrode 120-1 and the second transparent electrode 120-2 have a comb-tooth shape and are alternately arranged in the y-axis direction. The third transparent electrode 120-3 and the fourth transparent electrode 120-4 have a comb-tooth shape and are alternately arranged in the x-axis direction.

[0028] As described above, the first transparent electrode 120-1, the second transparent electrode 120-2, the third transparent electrode 120-3, and the fourth transparent electrode 120-4 of each of the four liquid crystal cells 100 extend in the same or substantially the same direction. That is, the optical element 10 does not have a configuration in which two of the four liquid crystal cells 100 must be rotated 90 degrees relative to the other two liquid crystal cells 100, but has a configuration in which the four liquid crystal cells 100 are stacked as they are, regardless of the rotation of each liquid crystal cell 100.

[0029] The extension direction of first transparent electrode 120-1 and second transparent electrode 120-2 is perpendicular to the extension direction of third transparent electrode 120-3 and fourth transparent electrode 120-4. In this specification, however, the intersecting directions may be described as being perpendicular even when they are shifted by about ±10 degrees from the perpendicular direction.

[0030] In each of the first liquid crystal cell 100-1, the second liquid crystal cell 100-2, the third liquid crystal cell 100-3, and the fourth liquid crystal cell 100-4, the first alignment film 130-1 has an alignment characteristic of aligning the long axes of the liquid crystal molecules in the y-axis direction, and the second alignment film 130-2 has an alignment characteristic of aligning the long axes of the liquid crystal molecules in the x-axis direction. In order to impart such alignment characteristics to the alignment film 130, for example, the first alignment film 130-1 is subjected to a rubbing treatment in the y-axis direction, and the second alignment film 130-2 is subjected to a rubbing treatment in the x-axis direction.

[0031] As described above, the first liquid crystal cell 100-1, the second liquid crystal cell 100-2, the third liquid crystal cell 100-3, and the fourth liquid crystal cell 100-4 have the same basic structure. Here, the properties of light transmitted through the liquid crystal cell 100 will be described with reference to Figures 3A and 3B.

[0032] 3A and 3B are schematic cross-sectional views illustrating the alignment direction of liquid crystal molecules in the liquid crystal layer 150 of the liquid crystal cell 100 of the optical element 10 according to one embodiment of the present invention and the properties of light transmitted through the liquid crystal cell 100. Specifically, Fig. 3A shows the liquid crystal cell 100 in a state where no voltage is applied to the transparent electrode 120, and Fig. 3B shows the liquid crystal cell 100 in a state where a voltage is applied to the transparent electrode 120.

[0033] FIG. 3A shows the liquid crystal cell 100 in a state where no voltage is applied to the transparent electrode 120. As shown in FIG. 3A, the liquid crystal molecules on the first alignment film 130-1 are aligned with their major axes along the y-axis direction. In other words, the alignment direction (initial alignment direction) of the liquid crystal molecules near the first substrate 110-1 side is the y-axis direction. On the other hand, the liquid crystal molecules on the second alignment film 130-2 are aligned with their major axes along the x-axis direction. In other words, the alignment direction (initial alignment direction) of the liquid crystal molecules near the second substrate 110-2 side is the x-axis direction. Therefore, the liquid crystal molecules in the liquid crystal layer 150 are aligned so as to be twisted 90 degrees in the z-axis direction as they move from the first substrate 110-1 to the second substrate 110-2. In this case, the polarization plane (the direction of the polarization axis or polarization component) of the light passing through the liquid crystal layer 150 is rotated 90 degrees according to the alignment direction of the liquid crystal molecules. That is, the light passing through the liquid crystal layer 150 is rotated.

[0034] 3B shows the liquid crystal cell 100 in a state in which a voltage is applied to the transparent electrodes 120. For example, a high voltage (H) is applied to the first transparent electrode 120-1 and the third transparent electrode 120-3, and a low voltage (L) is applied to the second transparent electrode 120-2 and the fourth transparent electrode 120-4. That is, a voltage is applied so that a potential difference occurs between two adjacent transparent electrodes 120. Note that, hereinafter, the electric field generated between two adjacent transparent electrodes 120 may be referred to as a lateral electric field.

[0035] The liquid crystal molecules in the vicinity of the first substrate 110-1 side are aligned in a convex arc shape in the y-axis direction with respect to the first substrate 110-1 by the transverse electric field between the first transparent electrode 120-1 and the second transparent electrode 120-2. The liquid crystal molecules in the vicinity of the second substrate 110-2 side are aligned in a convex arc shape in the x-axis direction with respect to the second substrate 110-2 by the transverse electric field between the third transparent electrode 120-3 and the fourth transparent electrode 120-4. On the other hand, since the cell gap d between the first substrate 110-1 and the second substrate 110-2 is sufficiently larger than the distance between adjacent electrodes on the substrate (for example, 10 μm≦d≦30 μm), the alignment state of the liquid crystal molecules located in the vicinity of the center between the first substrate 110-1 and the second substrate 110-2 does not change much from the initial alignment by any of the transverse electric fields. As described above, the first substrate 110-1 and the second substrate 110-2 are sufficiently separated from each other, so that the horizontal electric field between the first transparent electrode 120-1 and the second transparent electrode 120-2 of the first substrate 110-1 does not affect the alignment of the liquid crystal molecules on the second substrate 110-2 side, or is negligibly small. Similarly, the horizontal electric field between the third transparent electrode 120-3 and the fourth transparent electrode 120-4 of the second substrate 110-2 does not affect the alignment of the liquid crystal molecules on the first substrate 110-1 side, or is negligibly small.

[0036] The light emitted from the light source has a polarized component in the x-axis direction (P polarized component) and a polarized component in the y-axis direction (S polarized component), but for convenience, the light will be described below as being divided into a P polarized component and an S polarized component. That is, the light emitted from the light source includes a first polarized light 1000-1 having a P polarized component and a second polarized light 1000-2 having an S polarized component (see (1) in FIG. 3B).

[0037] In FIG. 3B, the P-polarized component of the first polarized light 1000-1 incident on the liquid crystal cell 100 is different from the alignment direction of the liquid crystal molecules on the first substrate 110-1 side, so the first polarized light 1000-1 is not diffused (see (2) in FIG. 3B). When the first polarized light 1000-1 travels from the first substrate 110-1 to the second substrate 110-2, the first polarized light 1000-1 is rotated while passing through the liquid crystal layer 150, and the polarization component changes from the P-polarized component to the S-polarized component. The first polarized light 1000-1 having the S-polarized component is different from the alignment direction of the liquid crystal molecules on the second substrate 110-2 side, so the first polarized light 1000-1 is not diffused (see (3) in FIG. 3B). In addition, the first polarized light 1000-1 output from the liquid crystal cell 100 has an S-polarized component (see (4) in FIG. 3B).

[0038] On the other hand, the S-polarized component of the second polarized light 1000-2 incident on the liquid crystal cell 100 is diffused in the y-axis direction according to the refractive index distribution of the liquid crystal molecules, since it is aligned in the same direction as the alignment direction of the liquid crystal molecules on the first substrate 110-1 side (see (2) in FIG. 3B). When the second polarized light 1000-2 travels from the first substrate 110-1 to the second substrate 110-2, the second polarized light 1000-2 is rotated while passing through the liquid crystal layer 150, and the polarization component changes from the S-polarized component to the P-polarized component. The P-polarized component of the second polarized light 1000-2 is diffused in the x-axis direction according to the refractive index distribution of the liquid crystal molecules, since it is aligned in the same direction as the alignment direction of the liquid crystal molecules on the second substrate 110-2 side (see (3) in FIG. 3B). The second polarized light 1000-2 output from the liquid crystal cell 100 has a P-polarized component (see (4) in FIG. 3B).

[0039] As can be seen from the above, the liquid crystal cell 100 can diffuse light in a predetermined direction by utilizing the direction of the transverse electric field formed by the transparent electrode 120, and the optical rotation and refractive index distribution of the liquid crystal molecules. By using a plurality of liquid crystal cells 100 in the optical element 10, the diffusion of light in each liquid crystal cell 100 can be controlled to form various light distribution shapes. The light distribution shape can also be controlled by the magnitude of the voltage applied to the transparent electrode 120.

[0040] Here, a comparison of light distribution characteristics between the optical element 10 of this embodiment and a conventional optical element will be shown with reference to Fig. 4. Note that the conventional optical element described here has a structure in which the third liquid crystal cell 100-3 and the fourth liquid crystal cell 100-4 of the optical element 10 are rotated by 90 degrees.

[0041] FIG. 4 is a graph showing the transmittance of the optical element 10 according to an embodiment of the present invention and a conventional optical element. Specifically, the graph in FIG. 4 shows the transmittance versus polar angle. The transmittance of the optical element 10 and the conventional optical element was measured using an LCD evaluation device (LCD-5200 manufactured by Otsuka Electronics Co., Ltd.). The direction of a polar angle of 0 degrees is a direction perpendicular to the second substrate 110-2 of the fourth liquid crystal cell 100-4. The transmittance at a polar angle of 0 degrees when no voltage is applied to the transparent electrode 120 is set to 100(%), and the transmittance when a voltage is applied to the transparent electrode 120 is measured. The absolute value of the polar angle at which the transmittance is half the transmittance at a polar angle of 0 degrees is defined as the half-width at half maximum.

[0042] The half width at half maximum of the optical element 10 was 38 degrees. On the other hand, the half width at half maximum of the conventional optical element was 29 degrees. It was found that the optical element 10 had a larger half width at half maximum than the conventional optical element as a result of the uniform diffusion of light in the liquid crystal cell 100.

[0043] As described above, the optical element 10 according to one embodiment of the present invention can uniformly diffuse light, and therefore can provide a uniform light distribution.

[0044] <Modification 1 of the First Embodiment> An optical element 10A, which is a modified example of the optical element 10 according to one embodiment of the present invention, will be described with reference to Fig. 5. In the following, when the configuration of the optical element 10A is similar to the configuration of the optical element 10, the description of the configuration of the optical element 10A may be omitted.

[0045] 5 is a schematic diagram illustrating the configuration of a transparent electrode 120A of a liquid crystal cell 100A of an optical element 10A according to one embodiment of the present invention. The optical element 10A includes four liquid crystal cells 100A. That is, in the optical element 10A, a first liquid crystal cell 100A-1, a second liquid crystal cell 100A-2, a third liquid crystal cell 100A-3, and a fourth liquid crystal cell 100A-4 are stacked in this order. Each of the first liquid crystal cell 100A-1, the second liquid crystal cell 100A-2, the third liquid crystal cell 100A-3, and the fourth liquid crystal cell 100A-4 includes a first substrate 110A-1 on which a first transparent electrode 120A-1 and a second transparent electrode 120A-2 extending in the x-axis direction are provided, and a second substrate 110A-2 on which a third transparent electrode 120A-3 and a fourth transparent electrode 120A-4 extending in the y-axis direction are provided. Note that the arrows along each substrate indicate the orientation direction (initial orientation direction) of the alignment film on the substrate (similarly in Figs. 6, 7, 9, 10, 11, 13, and 14).

[0046] A first electrode pattern and a second electrode pattern for driving liquid crystal are formed on the first substrate 110A-1 and the second substrate 110A-2, respectively. The first electrode pattern is a pattern in which the first transparent electrodes 120A-1 and the second transparent electrodes 120A-2 are alternately arranged in the y-axis direction. The second electrode pattern is a pattern in which the third transparent electrodes 120A-3 and the fourth transparent electrodes 120A-4 are alternately arranged in the x-axis direction.

[0047] The first electrode pattern of the liquid crystal cell 100A includes at least two inter-electrode pitches (distances in the y-axis direction between the center line of the first transparent electrode 120A-1 and the center line of the second transparent electrode 120A-2) between the first transparent electrode 120A-1 and the second transparent electrode 120A-2 (inter-electrode pitches p1, p2 in FIG. 5). The second electrode pattern of the liquid crystal cell 100A includes at least two inter-electrode pitches (distances in the x-direction between the center line of the third transparent electrode 120A-3 and the center line of the fourth transparent electrode 120A-4) (inter-electrode pitches p3, p4 in FIG. 5). Each electrode pattern may include two or more inter-electrode pitches. That is, each of the first electrode pattern and the second electrode pattern may have a configuration in which the inter-electrode pitches of two adjacent electrodes are all different. In this manner, in each electrode pattern, a configuration having an inter-electrode pitch of at least two or more is referred to as an unequal pitch.

[0048] It is also possible to employ a configuration in which the first electrode pattern and the second electrode pattern are the same.

[0049] The four liquid crystal cells 100A may each have the same first electrode pattern and second electrode pattern, or the first electrode pattern and the second electrode pattern of one liquid crystal cell 100A may be the same as the second electrode pattern and the first electrode pattern of another liquid crystal cell 100A. One of the first electrode pattern and the second electrode pattern may be the same, and the other of the first electrode pattern and the second electrode pattern may be different. Of course, the four liquid crystal cells 100A may have different first electrode patterns and second electrode patterns. However, when the four liquid crystal cells 100A have different first electrode patterns and second electrode patterns, the diffusion state in each liquid crystal cell 100A changes, so that the light intensity of a specific wavelength can be further suppressed from being strengthened. Therefore, it is preferable that the four liquid crystal cells 100A have first electrode patterns and second electrode patterns that are different from one another, that is, the electrode patterns of the four liquid crystal cells 100A are all configured with different unequal pitches.

[0050] As described above, the optical element 10A according to one embodiment of the present invention can suppress the light intensity of a specific wavelength from being increased, and therefore the optical element 10A can provide a uniform light distribution with reduced coloring.

[0051] <Modification 2 of the First Embodiment> An optical element 10B, which is another modified example of the optical element 10 according to one embodiment of the present invention, will be described with reference to Fig. 6. In the following, when the configuration of the optical element 10B is similar to that of the optical element 10, the description of the configuration of the optical element 10B may be omitted.

[0052] 6 is a schematic diagram illustrating the configuration of a transparent electrode 120B of a liquid crystal cell 100B of an optical element 10B according to one embodiment of the present invention. The optical element 10B includes four liquid crystal cells 100B. That is, in the optical element 10B, a first liquid crystal cell 100B-1, a second liquid crystal cell 100B-2, a third liquid crystal cell 100B-3, and a fourth liquid crystal cell 100B-4 are stacked in this order. Each of the first liquid crystal cell 100B-1, the second liquid crystal cell 100B-2, the third liquid crystal cell 100B-3, and the fourth liquid crystal cell 100B-4 includes a first substrate 110B-1 on which a first transparent electrode 120B-1 and a second transparent electrode 120B-2 extending in the x-axis direction are provided, and a second substrate 110B-2 on which a third transparent electrode 120B-3 and a fourth transparent electrode 120B-4 extending in the y-axis direction are provided.

[0053] A first electrode pattern and a second electrode pattern for driving liquid crystal are formed on the first substrate 110B-1 and the second substrate 110B-2, respectively. The first electrode pattern is a pattern in which the first transparent electrodes 120B-1 and the second transparent electrodes 120B-2 are alternately arranged in the y-axis direction. The second electrode pattern is a pattern in which the third transparent electrodes 120B-3 and the fourth transparent electrodes 120B-4 are alternately arranged in the y-axis direction.

[0054] In the first electrode pattern of the liquid crystal cell 100B, at least the width w1 of the comb teeth of the first transparent electrode 120B-1 is different from the width w2 of the comb teeth of the second transparent electrode 120B-2. In the second electrode pattern of the liquid crystal cell 100B, the width w3 of the comb teeth of the third transparent electrode 120B-3 is different from the width w4 of the comb teeth of the fourth transparent electrode 120B-4. The width w1 of the comb teeth of the first transparent electrode 120B-1 may be the same as or different from the width w3 of the comb teeth of the third transparent electrode 120B-3 and the width w4 of the comb teeth of the fourth transparent electrode. In addition, the width w3 of the comb teeth of the third transparent electrode 120B-3 may be the same as or different from the width w1 of the comb teeth of the first transparent electrode 120B-1 and the width w2 of the comb teeth of the second transparent electrode 120B-2. The width w1 of the comb teeth of the first transparent electrode 120B-1 may be different from each other, or may be partially the same. The same is true for the width w2 of the comb teeth of the second transparent electrode 120B-2, the width w3 of the comb teeth of the third transparent electrode 120B-3, and the width w4 of the comb teeth of the fourth transparent electrode 120B-4. The intervals between the adjacent first transparent electrode 120B-1 and the second transparent electrode 120B-2 may all be the same, may be partially the same, or may all be different. The width w1 of the comb teeth of the first transparent electrode 120B-1 and the width w2 of the comb teeth of the second transparent electrode 120B-2 are different, and / or the intervals between the comb teeth of the first transparent electrode 120-1 and the second transparent electrode 120-2 are different, thereby realizing an unequal pitch in the first electrode pattern. The same is true for the second electrode pattern.

[0055] The four liquid crystal cells 100B have different first and second electrode patterns. For example, the width w1 of the first transparent electrode of the first liquid crystal cell 100B-1 is different from the width w1 of each of the second liquid crystal cell 100B-2, the third liquid crystal cell 100B-3, and the fourth liquid crystal cell 100B-4. In this case, the diffusion state in each liquid crystal cell 100B changes, so that it is possible to suppress the light intensity of a specific wavelength from being strengthened.

[0056] As described above, the optical element 10B according to one embodiment of the present invention can suppress the light intensity of a specific wavelength from being increased, and therefore the optical element 10B can provide a uniform light distribution with reduced coloring.

[0057] <Second embodiment> An optical element 20 according to one embodiment of the present invention will be described with reference to Fig. 7 and Fig. 8. In the following, when the configuration of the optical element 20 is similar to that of the optical element 10, the description of the configuration of the optical element 20 may be omitted.

[0058] 7 is a schematic diagram illustrating the configuration of the transparent electrode 220 of the liquid crystal cell 200 of the optical element 20 according to one embodiment of the present invention. The optical element 20 includes four liquid crystal cells 200. That is, in the optical element 20, a first liquid crystal cell 200-1, a second liquid crystal cell 200-2, a third liquid crystal cell 200-3, and a fourth liquid crystal cell 200-4 are sequentially stacked. Each of the first liquid crystal cell 200-1, the second liquid crystal cell 200-2, the third liquid crystal cell 200-3, and the fourth liquid crystal cell 200-4 includes a first substrate 210-1 on which a first transparent electrode 220-1 and a second transparent electrode 220-2 are provided, and a second substrate 210-2 on which a third transparent electrode 220-3 and a fourth transparent electrode 220-4 are provided.

[0059] A first electrode pattern and a second electrode pattern for driving the liquid crystal are formed on the first substrate 210-1 and the second substrate 210-2, respectively. Here, the first electrode pattern and the second electrode pattern of the liquid crystal cell 200 will be described in detail with reference to FIG.

[0060] FIG. 8 is a schematic diagram illustrating the configuration of the first electrode pattern and the second electrode pattern of the liquid crystal cell 200 of the optical element 20 according to one embodiment of the present invention. The first electrode pattern is a pattern in which the first transparent electrode 220-1 and the second transparent electrode 220-2 extending in a direction having a first angle θ1 with respect to the x-axis direction are alternately arranged in the y-axis direction. The second electrode pattern is a pattern in which the third transparent electrode 220-3 and the fourth transparent electrode 220-4 extending in a direction having a second angle θ2 with respect to the y-axis direction are alternately arranged in the x-axis direction. The first angle θ1 may be the same as the second angle θ2, and in this case, the transparent electrode 220 on the first substrate 110-1 side and the transparent electrode 220 on the second substrate 110-2 side are orthogonal to each other in a plan view. Of course, the first angle θ1 and the second angle θ2 may be different from each other. Each of the first angle θ1 and the second angle θ2 is -5 degrees or more and +5 degrees or less, and preferably -3 degrees or more and +3 degrees or less. Although there is a difference between the first angle θ1 and the second angle θ2, the extension directions of the first transparent electrode 220-1, the second transparent electrode 220-2, the third transparent electrode 220-3, and the fourth transparent electrode 220-4 of each of the four liquid crystal cells 200 are basically the same. That is, the optical element 20 is not configured such that two of the four liquid crystal cells 200 must be rotated 90 degrees relative to the other two liquid crystal cells 200, but has a configuration in which the four liquid crystal cells 200 are stacked regardless of the rotation of each liquid crystal cell 200.

[0061] 8 indicates the direction of the initial alignment of the first alignment film 130-1 with respect to the first electrode pattern of the first substrate 210-1. As indicated by the arrow A, the initial alignment direction is parallel to the y-axis. The direction of the initial alignment can be set arbitrarily within a range from a direction parallel to the y-axis to a direction perpendicular to the first electrode pattern (arrow B indicated by a two-dot chain line in the figure). That is, the direction of the initial alignment in the first electrode pattern can be set arbitrarily within a range from a direction parallel to the y-axis to θ1 with respect to the y-axis.

[0062] Similarly, arrow C in FIG. 8 indicates the direction of the initial alignment of the second alignment film 130-2 with respect to the second electrode pattern of the second substrate 210-2. As indicated by arrow C, the initial alignment direction is parallel to the x-axis. The direction of the initial alignment can be set arbitrarily within a range from a direction parallel to the x-axis to a direction perpendicular to the second electrode pattern (arrow D indicated by a two-dot chain line in the figure). That is, the direction of the initial alignment in the second electrode pattern can be set arbitrarily within a range from a direction parallel to the x-axis to θ2 with respect to the y-axis.

[0063] It should be noted that the direction of the initial orientation shown in FIG. 7 is shown representatively by the arrow A in the first electrode pattern and the arrow C in the second electrode pattern, but it goes without saying that the direction of the initial orientation shown in FIG. 7 can be set within a range perpendicular to the corresponding electrode pattern as described above.

[0064] The four liquid crystal cells 200 have a first electrode pattern and a second electrode pattern that are different from each other. Specifically, the first liquid crystal cell 200-1, the second liquid crystal cell 200-2, the third liquid crystal cell 200-3, and the fourth liquid crystal cell 200-4 have a first angle θ1 or a second angle θ2 that are different from each other. For example, when the first angle θ1 and the second angle θ2 are the same in each liquid crystal cell 200 (for example, when the first angle θ1 and the second angle θ2 of the first liquid crystal cell 200-1 are the same), the first angle θ1 of the first liquid crystal cell 200-1, the second liquid crystal cell 200-2, the third liquid crystal cell 200-3, and the fourth liquid crystal cell 200-4 is -1 degree, +1 degree, +3 degrees, and -3 degrees, respectively. In this case, the diffusion state in each liquid crystal cell 200 changes, so that it is possible to prevent the light intensity of a specific wavelength from being strengthened.

[0065] 7, when paying attention to the initial alignment direction of each substrate of the four liquid crystal cells, the alignment direction of the first substrate 210-1 of the first liquid crystal cell 200-1 and the alignment direction of the first substrate 210-1 of the fourth liquid crystal cell 200-4 are the same (first alignment direction), and the alignment direction of the first substrate 210-1 of the second liquid crystal cell 200-2 and the alignment direction of the first substrate 210-1 of the third liquid crystal cell 200-3 are the same (second alignment direction) and are directed in the opposite direction to the first alignment direction. In addition, the alignment direction of the second substrate 210-2 of the first liquid crystal cell 200-1 and the alignment direction of the second substrate 210-2 of the fourth liquid crystal cell 200-4 are the same (third alignment direction) and cross the first alignment direction. The second substrate 210-2 of the second liquid crystal cell 200-2 and the second substrate 210-2 of the third liquid crystal cell 200-3 have the same alignment direction (fourth alignment direction) and are opposite to the third alignment direction. By setting the initial alignment direction in each substrate in this manner, the initial alignment directions are well balanced when viewed from the perspective of the entire optical element 20, and the left-right or up-down balance of the light passing through the optical element is also maintained.

[0066] As described above, the optical element 20 according to one embodiment of the present invention can suppress the light intensity of a specific wavelength from being strengthened. Therefore, the optical element 20 can obtain a uniform light distribution with suppressed coloring.

[0067] <Modification 1 of the second embodiment> An optical element 20A, which is a modified example of the optical element 20 according to one embodiment of the present invention, will be described with reference to Fig. 9. In the following, when the configuration of the optical element 20A is similar to that of the optical element 20, the description of the configuration of the optical element 20A may be omitted.

[0068] 9 is a schematic diagram illustrating the configuration of the transparent electrode 220A of the liquid crystal cell 200A of the optical element 20A according to one embodiment of the present invention. The optical element 20A includes four liquid crystal cells 200A. That is, in the optical element 20A, a first liquid crystal cell 200A-1, a second liquid crystal cell 200A-2, a third liquid crystal cell 200A-3, and a fourth liquid crystal cell 200A-4 are sequentially stacked. Each of the first liquid crystal cell 200A-1, the second liquid crystal cell 200A-2, the third liquid crystal cell 200A-3, and the fourth liquid crystal cell 200A-4 includes a first substrate 210A-1 on which the first transparent electrode 220A-1 and the second transparent electrode 220A-2 are provided, and a second substrate 210A-2 on which the third transparent electrode 220A-3 and the fourth transparent electrode 220A-4 are provided.

[0069] A first electrode pattern and a second electrode pattern for driving liquid crystal are formed on the first substrate 210A-1 and the second substrate 210A-2, respectively. The first electrode pattern is a pattern in which a first transparent electrode 220A-1 and a second transparent electrode 220A-2 extending in a direction having a first angle θ1 with respect to the x-axis direction are alternately arranged in the y-axis direction, and includes at least two inter-electrode pitches between the first transparent electrode 220A-1 and the second transparent electrode 220A-2 (see inter-electrode pitches p1 and p2 in FIG. 9). In addition, the second electrode pattern is a pattern in which the third transparent electrodes 220A-3 and the fourth transparent electrodes 220A-4 extending in a direction having a second angle θ2 with respect to the y-axis direction are alternately arranged in the x-axis direction, and includes at least two inter-electrode pitches between the third transparent electrodes 220A-3 and the fourth transparent electrodes 220A-4 (see inter-electrode pitches p3 and p4 in Figure 9).

[0070] The four liquid crystal cells 200A have a configuration in which the first electrode pattern and the second electrode pattern are different from each other. Specifically, the first liquid crystal cell 200A-1, the second liquid crystal cell 200A-2, the third liquid crystal cell 200A-3, and the fourth liquid crystal cell 200A-4 have a first angle θ1 or a second angle θ2 that are different from each other. For example, when the first angle θ1 and the second angle θ2 are the same in each liquid crystal cell 200A (for example, when the first angle θ1 and the second angle θ2 of the first liquid crystal cell 200A-1 are the same), the first angle θ1 of the first liquid crystal cell 200A-1, the second liquid crystal cell 200A-2, the third liquid crystal cell 200A-3, and the fourth liquid crystal cell 200A-4 is -1 degree, +1 degree, +3 degrees, and -3 degrees, respectively. In this case, the diffusion state in each liquid crystal cell 200A changes, so that the light intensity of a specific wavelength can be further prevented from being strengthened.

[0071] The width w1 of the comb teeth of the first transparent electrode 220A-1 may be different from each other, or may be partially the same. The same is true for the width w2 of the comb teeth of the second transparent electrode 220A-2, the width w3 of the comb teeth of the third transparent electrode 220A-3, and the width w4 of the comb teeth of the fourth transparent electrode 220A-4. The intervals between two adjacent first transparent electrodes 220A-1 and second transparent electrodes 220A-2 may all be the same, may be partially the same, or may all be different. The width w1 of the comb teeth of the first transparent electrode 220A-1 and the width w2 of the comb teeth of the second transparent electrode 220A-2 are different, and / or the intervals between the comb teeth of the first transparent electrode 220A-1 and the second transparent electrode 220A-2 are different, thereby realizing an unequal pitch in the first electrode pattern. The same is true for the second electrode pattern.

[0072] As described above, the optical element 20A according to one embodiment of the present invention can suppress the light intensity of a specific wavelength from being increased, and therefore the optical element 20A can provide a uniform light distribution with reduced coloring.

[0073] <Modification 2 of the second embodiment> An optical element 20B, which is another modified example of the optical element 20 according to one embodiment of the present invention, will be described with reference to Fig. 10. In the following, when the configuration of the optical element 20B is similar to the configuration of the optical element 20 or the optical element 20A, the description of the configuration of the optical element 20B may be omitted.

[0074] 10 is a schematic diagram illustrating the configuration of the transparent electrode 220B of the liquid crystal cell 200B of the optical element 20B according to one embodiment of the present invention. The optical element 20B includes four liquid crystal cells 200B. That is, in the optical element 20B, a first liquid crystal cell 200B-1, a second liquid crystal cell 200B-2, a third liquid crystal cell 200B-3, and a fourth liquid crystal cell 200B-4 are sequentially stacked. Each of the first liquid crystal cell 200B-1, the second liquid crystal cell 200B-2, the third liquid crystal cell 200B-3, and the fourth liquid crystal cell 200B-4 includes a first substrate 210B-1 on which the first transparent electrode 220B-1 and the second transparent electrode 220B-2 are provided, and a second substrate 210B-2 on which the third transparent electrode 220B-3 and the fourth transparent electrode 220B-4 are provided.

[0075] A first electrode pattern and a second electrode pattern for driving liquid crystal are formed on the first substrate 210B-1 and the second substrate 210B-2, respectively. The first electrode pattern is a pattern in which a first transparent electrode 220B-1 and a second transparent electrode 220B-2 extending in a direction having a first angle θ1 with respect to the x-axis direction are alternately arranged in the y-axis direction. The second electrode pattern is a pattern in which a third transparent electrode 220B-3 and a fourth transparent electrode 220B-4 extending in a direction having a second angle θ2 with respect to the y-axis direction are alternately arranged in the x-axis direction.

[0076] The first electrode pattern of each of the first liquid crystal cell 200B-1 and the third liquid crystal cell 200B-3 includes at least two inter-electrode pitches between the first transparent electrode 220B-1 and the second transparent electrode 220B-2 (see inter-electrode pitches p1 and p2 in FIG. 10). Also, the second electrode pattern of each of the first liquid crystal cell 200B-1 and the third liquid crystal cell 200B-3 includes at least two inter-electrode pitches between the third transparent electrode 220B-3 and the fourth transparent electrode 220B-4 (see inter-electrode pitches p3 and p4 in FIG. 10).

[0077] On the other hand, the first electrode pattern of each of the second liquid crystal cell 200B-2 and the fourth liquid crystal cell 200B-4 includes one inter-electrode pitch between the first transparent electrode 220B-1 and the second transparent electrode 220B-2 (see inter-electrode pitch p5 in FIG. 10). Also, the second electrode pattern of each of the second liquid crystal cell 200B-2 and the fourth liquid crystal cell 200B-4 includes one inter-electrode pitch between the third transparent electrode 220B-3 and the fourth transparent electrode 220B-4 (see inter-electrode pitch p6 in FIG. 10). That is, the electrode patterns of each of the second liquid crystal cell 200B-2 and the fourth liquid crystal cell 200B-4 are all of equal pitch. In each of the second liquid crystal cell 200B-2 and the fourth liquid crystal cell 200B-4, the inter-electrode pitch p5 of the first electrode pattern and the inter-electrode pitch p6 of the second electrode pattern may be the same or different. Also, a configuration in which the inter-electrode pitch p5 of the first electrode pattern and the inter-electrode pitch p6 of the second electrode pattern are the same is also possible.

[0078] The first liquid crystal cell 200B-1, the second liquid crystal cell 200B-2, the third liquid crystal cell 200B-3, and the fourth liquid crystal cell 200B-4 have different first angles θ1 or second angles θ2. For example, when the first angle θ1 and the second angle θ2 are the same in each liquid crystal cell 200B (for example, when the first angle θ1 and the second angle θ2 of the first liquid crystal cell 200-1 are the same), the first angles θ1 of the first liquid crystal cell 200B-1, the second liquid crystal cell 200B-2, the third liquid crystal cell 200B-3, and the fourth liquid crystal cell 200B-4 are -1 degree, +1 degree, +3 degrees, and -3 degrees, respectively. Therefore, even if the second liquid crystal cell 200B-2 and the fourth liquid crystal cell 200B-4 have the same inter-electrode pitch, the four liquid crystal cells 200B have different first electrode patterns and second electrode patterns because the first angle θ1 is different. In this case, the diffusion state in each liquid crystal cell 200B changes, so that it is possible to suppress the light intensity of a specific wavelength from being strengthened.

[0079] The widths w1 of the comb teeth of the first transparent electrode 220B-1 in each of the first liquid crystal cell 200B-1 and the third liquid crystal cell 200B-3 may be different from each other, or may be partially the same. The same is true for the widths w2 of the comb teeth of the second transparent electrode 220B-2, the widths w3 of the comb teeth of the third transparent electrode 220B-3, and the widths w4 of the comb teeth of the fourth transparent electrode 220B-4 in each of the first liquid crystal cell 200B-1 and the third liquid crystal cell 200B-3. In addition, in the first liquid crystal cell 200B-1 and the third liquid crystal cell 200B-3, the intervals between the adjacent first transparent electrodes 220B-1 and second transparent electrodes 220B-2 may all be the same, may be partially the same, or may all be different. The first electrode pattern has an uneven pitch because the width w1 of the teeth of the first transparent electrode 220B-1 is different from the width w2 of the teeth of the second transparent electrode 220B-2 and / or the spacing between the teeth of the first transparent electrode 220B-1 and the second transparent electrode 220B-2 is different. The same applies to the second electrode pattern.

[0080] The optical element 20B described above has a configuration in which the electrode patterns of the first liquid crystal cell 200B-1 and the third liquid crystal cell 200B-3 have an unequal pitch, and the electrode patterns of the second liquid crystal cell 200B-2 and the fourth liquid crystal cell 200B-4 have an equal pitch. However, the optical element 20B can also adopt a configuration in which the electrode patterns of the first liquid crystal cell 200B-1 and the third liquid crystal cell 200B-3 have an equal pitch, and the electrode patterns of the second liquid crystal cell 200B-2 and the fourth liquid crystal cell 200B-4 have an unequal pitch. The optical element 20B can also adopt a configuration in which the electrode patterns of the first liquid crystal cell 200B-1 and the fourth liquid crystal cell 200B-4 have an unequal pitch, and the electrode patterns of the second liquid crystal cell 200B-2 and the third liquid crystal cell 200B-3 have an equal pitch. Furthermore, it is also possible to employ a configuration in which one or three of the four liquid crystal cells 200B have an uneven pitch and the other three or one have an even pitch, or vice versa.

[0081] As described above, the optical element 20B according to one embodiment of the present invention can suppress the enhancement of a specific light intensity. Therefore, the optical element 20B can obtain a uniform light distribution with suppressed coloring.

[0082] <Third embodiment> An optical element 30 according to one embodiment of the present invention will be described with reference to Fig. 11 and Fig. 12. In the following, when the configuration of the optical element 30 is similar to the configuration of the optical element 10 or the optical element 20, the description of the configuration of the optical element 30 may be omitted.

[0083] 11 is a schematic diagram illustrating the configuration of the transparent electrode 320 of the liquid crystal cell 300 of the optical element 30 according to one embodiment of the present invention. The optical element 30 includes four liquid crystal cells 300. That is, in the optical element 30, a first liquid crystal cell 300-1, a second liquid crystal cell 300-2, a third liquid crystal cell 300-3, and a fourth liquid crystal cell 300-4 are sequentially stacked. Each of the first liquid crystal cell 300-1, the second liquid crystal cell 300-2, the third liquid crystal cell 300-3, and the fourth liquid crystal cell 300-4 includes a first substrate 310-1 on which a first transparent electrode 320-1 and a second transparent electrode 320-2 are provided, and a second substrate 310-2 on which a third transparent electrode 320-3 and a fourth transparent electrode 320-4 are provided.

[0084] A first electrode pattern and a second electrode pattern for driving the liquid crystal are formed on the first substrate 310-1 and the second substrate 310-2, respectively. Here, the first electrode pattern and the second electrode pattern of the liquid crystal cell 300 will be described in detail with reference to FIG.

[0085] FIG. 12 is a schematic diagram illustrating the configuration of the first electrode pattern and the second electrode pattern of the liquid crystal cell 300 of the optical element 30 according to one embodiment of the present invention. The first electrode pattern is a pattern in which a first transparent electrode 320-1 and a second transparent electrode 320-2 having a dogleg shape are alternately arranged in the y-axis direction. Specifically, the first transparent electrode 320-1 extends in a direction having a first angle θ1 with respect to the x-axis direction and bends in a direction having a second angle θ2 with respect to the x-axis direction. The second transparent electrode 320-2 extends in a direction having a second angle θ2 with respect to the x-axis direction and bends in a direction having a first angle θ1 with respect to the x-axis direction. The second electrode pattern is a pattern in which a third transparent electrode 320-3 and a fourth transparent electrode 320-4 having a dogleg shape are alternately arranged in the x-axis direction. Specifically, the third transparent electrode 320-3 extends in a direction having a third angle θ3 with respect to the y-axis direction and bends in a direction having a fourth angle θ4 with respect to the y-axis direction. The fourth transparent electrode 320-4 extends in a direction having a fourth angle θ4 with respect to the y-axis direction and bends in a direction having a third angle θ3 with respect to the y-axis direction.

[0086] The first angle θ1 may be the same as or different from the third angle θ3. The second angle θ2 may be the same as or different from the fourth angle θ4. Since the transparent electrode 320 has a dogleg shape, the first angle θ1 and the second angle θ2 have opposite signs of positive and negative, and the third angle θ3 and the fourth angle θ4 have opposite signs of positive and negative. Each of the first angle θ1, the second angle θ2, the third angle θ3, and the fourth angle θ4 is between -5 degrees and +5 degrees, and preferably between -3 degrees and +3 degrees. Although there are differences in the first angle θ1, the second angle θ2, the third angle θ3, and the fourth angle θ4, the extending directions of the first transparent electrode 320-1, the second transparent electrode 320-2, the third transparent electrode 320-3, and the fourth transparent electrode 320-4 of each of the four liquid crystal cells 300 are basically the same. That is, the optical element 30 is not configured such that two of the four liquid crystal cells 300 must be rotated 90 degrees relative to the other two liquid crystal cells 300, but has a configuration in which the four liquid crystal cells 300 are stacked regardless of the rotation of each liquid crystal cell 300.

[0087] 12 indicates the direction of the initial alignment of the alignment film with respect to the first electrode pattern of the first substrate 310-1. As indicated by the arrow E, the initial alignment direction is parallel to the y-axis.

[0088] 12 indicates the direction of the initial alignment of the alignment film with respect to the second electrode pattern of the second substrate 310-2. As indicated by the arrow F, the initial alignment direction is parallel to the x-axis.

[0089] The four liquid crystal cells 300 have different first and second electrode patterns. Specifically, the first liquid crystal cell 300-1, the second liquid crystal cell 300-2, the third liquid crystal cell 300-3, and the fourth liquid crystal cell 300-4 have at least one of the first angle θ1 and the second angle θ2 different from each other. For example, when the first angle θ1 and the second angle θ2 are the same as the third angle θ3 and the fourth angle θ4 in each liquid crystal cell 300 (for example, when the first angle θ1 and the second angle θ2 of the first liquid crystal cell 300-1 are the same as the third angle θ3 and the fourth angle θ4), the (first angle θ1, the second angle θ2) of the first liquid crystal cell 300-1, the second liquid crystal cell 300-2, the third liquid crystal cell 300-3, and the fourth liquid crystal cell 300-4 are (-1 degree, +3 degrees), (+1 degree, -3 degrees), (+3 degrees, -1 degree), and (-3 degrees, +1 degree), respectively. In this case, the diffusion state in each liquid crystal cell 300 changes, so that it is possible to suppress the light intensity of a specific wavelength from being strengthened. Furthermore, since the transparent electrodes 320 have a dogleg shape, it is possible to prevent the transparent electrodes 320 from overlapping with a periodicity.

[0090] As described above, in the optical element 30 according to one embodiment of the present invention, it is possible to prevent the transparent electrodes 320 from overlapping with a periodicity and to suppress the light intensity of a specific wavelength from being strengthened. Therefore, in the optical element 30, it is possible to obtain a uniform light distribution with suppressed moire and coloring.

[0091] <Modification 1 of the third embodiment> An optical element 30A, which is a modified example of the optical element 30 according to one embodiment of the present invention, will be described with reference to Fig. 13. In the following, when the configuration of the optical element 30A is similar to that of the optical element 30, the description of the configuration of the optical element 30A may be omitted.

[0092] 13 is a schematic diagram illustrating the configuration of the transparent electrode 320A of the liquid crystal cell 300A of the optical element 30A according to one embodiment of the present invention. The optical element 30A includes four liquid crystal cells 300A. That is, in the optical element 30A, a first liquid crystal cell 300A-1, a second liquid crystal cell 300A-2, a third liquid crystal cell 300A-3, and a fourth liquid crystal cell 300A-4 are sequentially stacked. Each of the first liquid crystal cell 300A-1, the second liquid crystal cell 300A-2, the third liquid crystal cell 300A-3, and the fourth liquid crystal cell 300A-4 includes a first substrate 310A-1 on which the first transparent electrode 320A-1 and the second transparent electrode 320A-2 are provided, and a second substrate 310A-2 on which the third transparent electrode 320A-3 and the fourth transparent electrode 320A-4 are provided.

[0093] A first electrode pattern and a second electrode pattern for driving liquid crystal are formed on the first substrate 310A-1 and the second substrate 310A-2, respectively. The first electrode pattern is a pattern in which a first transparent electrode 320A-1 and a second transparent electrode 320A-2 having a V-shape are alternately arranged in the y-axis direction, and includes at least two inter-electrode pitches between the first transparent electrode 320A-1 and the second transparent electrode 320A-2 (see inter-electrode pitches p1 and p2 in FIG. 13). The second electrode pattern is a pattern in which a third transparent electrode 320A-3 and a fourth transparent electrode 320A-4 having a V-shape are alternately arranged in the x-axis direction, and includes at least two inter-electrode pitches between the third transparent electrode 320A-3 and the fourth transparent electrode 320A-4 (see inter-electrode pitches p3 and p4 in FIG. 13).

[0094] The four liquid crystal cells 300A have different first and second electrode patterns. Specifically, the first liquid crystal cell 300A-1, the second liquid crystal cell 300A-2, the third liquid crystal cell 300A-3, and the fourth liquid crystal cell 300A-4 have at least one of the first angle θ1 and the second angle θ2 different from each other. For example, when the first angle θ1 and the second angle θ2 are the same as the third angle θ3 and the fourth angle θ4 in each liquid crystal cell 300A (for example, when the first angle θ1 and the second angle θ2 of the first liquid crystal cell 300A-1 are the same as the third angle θ3 and the fourth angle θ4), the (first angle θ1, the second angle θ2) of the first liquid crystal cell 300A-1, the second liquid crystal cell 300A-2, the third liquid crystal cell 300A-3, and the fourth liquid crystal cell 300A-4 are (-1 degree, +3 degrees), (+1 degree, -3 degrees), (+3 degrees, -1 degree), and (-3 degrees, +1 degree), respectively. In this case, the diffusion state in each liquid crystal cell 300A changes, so that it is possible to suppress the light intensity of a specific wavelength from being strengthened. Furthermore, since the transparent electrodes 320A have a dogleg shape, it is possible to prevent the transparent electrodes 320A from overlapping with a periodicity.

[0095] The width w1 of the comb teeth of the first transparent electrode 320A-1 may be different from each other, or may be partially the same. The same is true for the width w2 of the comb teeth of the second transparent electrode 320A-2, the width w3 of the comb teeth of the third transparent electrode 320A-3, and the width w4 of the comb teeth of the fourth transparent electrode 320A-4. The intervals between two adjacent first transparent electrodes 320A-1 and second transparent electrodes 320A-2 may all be the same, may be partially the same, or may all be different. The width w1 of the comb teeth of the first transparent electrode 320A-1 and the width w2 of the comb teeth of the second transparent electrode 320A-2 are different, and / or the intervals between the comb teeth of the first transparent electrode 320A-1 and the second transparent electrode 320A-2 are different, thereby realizing an unequal pitch in the first electrode pattern. The same is true for the second electrode pattern.

[0096] As described above, in the optical element 30A according to one embodiment of the present invention, the transparent electrodes 320A can be prevented from overlapping with a periodicity, and the light intensity of a specific wavelength can be suppressed from being strengthened. Therefore, in the optical element 30A, a uniform light distribution with suppressed moire and coloring can be obtained.

[0097] <Modification 2 of the third embodiment> An optical element 30B, which is another modified example of the optical element 30 according to one embodiment of the present invention, will be described with reference to Fig. 14. In the following, when the configuration of the optical element 30B is similar to the configuration of the optical element 30 or the optical element 30A, the description of the configuration of the optical element 30B may be omitted.

[0098] 14 is a schematic diagram illustrating the configuration of the transparent electrode 320B of the liquid crystal cell 300B of the optical element 30B according to one embodiment of the present invention. The optical element 30B includes four liquid crystal cells 300B. That is, in the optical element 30B, a first liquid crystal cell 300B-1, a second liquid crystal cell 300B-2, a third liquid crystal cell 300B-3, and a fourth liquid crystal cell 300B-4 are sequentially stacked. Each of the first liquid crystal cell 300B-1, the second liquid crystal cell 300B-2, the third liquid crystal cell 300B-3, and the fourth liquid crystal cell 300B-4 includes a first substrate 310B-1 on which the first transparent electrode 320B-1 and the second transparent electrode 320B-2 are provided, and a second substrate 310B-2 on which the third transparent electrode 320B-3 and the fourth transparent electrode 320B-4 are provided.

[0099] A first electrode pattern and a second electrode pattern for driving liquid crystal are formed on the first substrate 310B-1 and the second substrate 310B-2, respectively. The first electrode pattern is a pattern in which a first transparent electrode 320B-1 and a second transparent electrode 320B-2 having a V-shape are alternately arranged in the y-axis direction. The second electrode pattern is a pattern in which a third transparent electrode 320B-3 and a fourth transparent electrode 320B-4 having a V-shape are alternately arranged in the x-axis direction.

[0100] The first electrode pattern of each of the first liquid crystal cell 300B-1 and the third liquid crystal cell 300B-3 includes at least two inter-electrode pitches between the first transparent electrode 320B-1 and the second transparent electrode 320B-2 (inter-electrode pitches p1, p2 in FIG. 14). Also, the second electrode pattern of each of the first liquid crystal cell 300B-1 and the third liquid crystal cell 300B-3 includes at least two inter-electrode pitches between the third transparent electrode 320B-3 and the fourth transparent electrode 320B-4 (inter-electrode pitches p3, p4 in FIG. 14).

[0101] On the other hand, the first electrode pattern of each of the second liquid crystal cell 300B-2 and the fourth liquid crystal cell 300B-4 includes one inter-electrode pitch between the first transparent electrode 320B-1 and the second transparent electrode 320B-2 (inter-electrode pitch p5 in FIG. 14). Also, the second electrode pattern of each of the second liquid crystal cell 300B-2 and the fourth liquid crystal cell 200B-4 includes one inter-electrode pitch between the third transparent electrode 320B-3 and the fourth transparent electrode 320B-4 (inter-electrode pitch p6 in FIG. 14). That is, the electrode patterns of each of the second liquid crystal cell 300B-2 and the fourth liquid crystal cell 300B-4 are all of equal pitch. In each of the second liquid crystal cell 300B-2 and the fourth liquid crystal cell 300B-4, the inter-electrode pitch p5 of the first electrode pattern and the inter-electrode pitch p6 of the second electrode pattern may be the same or different. Also, a configuration in which the inter-electrode pitch p5 of the first electrode pattern and the inter-electrode pitch p6 of the second electrode pattern are the same is also possible.

[0102] The first liquid crystal cell 300B-1, the second liquid crystal cell 300B-2, the third liquid crystal cell 300B-3, and the fourth liquid crystal cell 300B-4 differ from each other in at least one of the first angle θ1 and the second angle θ2. For example, when the first angle θ1 and the second angle θ2 of each liquid crystal cell 300B are the same as the third angle θ3 and the fourth angle θ4, respectively (e.g., when the first angle θ1 and the second angle θ2 of the first liquid crystal cell 300B-1 are the same as the third angle θ3 and the fourth angle θ4, respectively), the (first angle θ1, second angle θ2) of the first liquid crystal cell 300B-1, the second liquid crystal cell 300B-2, the third liquid crystal cell 300B-3, and the fourth liquid crystal cell 300B-4 are (-1 degree, +3 degrees), (+1 degree, -3 degrees), (+3 degrees, -1 degree), and (-3 degrees, +1 degree), respectively. Therefore, even if the inter-electrode pitch of the second liquid crystal cell 300B-2 and the fourth liquid crystal cell 300B-4 is the same, at least one of the first angle θ1 and the second angle θ2 is different, so that the four liquid crystal cells 300B have different first electrode patterns and second electrode patterns. In this case, the diffusion state in each liquid crystal cell 300B changes, so that it is possible to suppress the light intensity of a specific wavelength from being strengthened. In addition, since the transparent electrodes 320B have a dogleg shape, it is possible to prevent the transparent electrodes 320B from overlapping with a periodicity.

[0103] The widths w1 of the comb teeth of the first transparent electrode 320B-1 in each of the first liquid crystal cell 300B-1 and the third liquid crystal cell 300B-3 may be different from each other, or may be partially the same. The same is true for the widths w2 of the comb teeth of the second transparent electrode 320B-2, the widths w3 of the comb teeth of the third transparent electrode 320B-3, and the widths w4 of the comb teeth of the fourth transparent electrode 320B-4 in each of the first liquid crystal cell 300B-1 and the third liquid crystal cell 300B-3. In addition, in the first liquid crystal cell 300B-1 and the third liquid crystal cell 300B-3, the intervals between the first transparent electrode 320B-1 and the second transparent electrode 320B-2 adjacent to each other may all be the same, may be partially the same, or may all be different. The first electrode pattern has an uneven pitch because the width w1 of the teeth of the first transparent electrode 320B-1 is different from the width w2 of the teeth of the second transparent electrode 320B-2 and / or the spacing between the teeth of the first transparent electrode 320B-1 and the second transparent electrode 320B-2 is different. The same applies to the second electrode pattern.

[0104] The optical element 30B described above has a configuration in which the electrode patterns of the first liquid crystal cell 300B-1 and the third liquid crystal cell 300B-3 have an unequal pitch, and the electrode patterns of the second liquid crystal cell 300B-2 and the fourth liquid crystal cell 300B-4 have an equal pitch. However, the optical element 30B can also adopt a configuration in which the electrode patterns of the first liquid crystal cell 300B-1 and the third liquid crystal cell 300B-3 have an equal pitch, and the electrode patterns of the second liquid crystal cell 300B-2 and the fourth liquid crystal cell 300B-4 have an unequal pitch. The optical element 30B can also adopt a configuration in which the electrode patterns of the first liquid crystal cell 300B-1 and the fourth liquid crystal cell 300B-4 have an unequal pitch, and the electrode patterns of the second liquid crystal cell 300B-2 and the third liquid crystal cell 300B-3 have an equal pitch. Furthermore, it is also possible to employ a configuration in which one or three of the four liquid crystal cells 300B have an uneven pitch and the other three or one have an equal pitch, or vice versa.

[0105] As described above, in the optical element 30B according to one embodiment of the present invention, the transparent electrodes 320B can be prevented from overlapping with a periodicity, and a specific light intensity can be suppressed from being strengthened. Therefore, in the optical element 30B, a uniform light distribution with suppressed moire and coloring can be obtained.

[0106] Within the scope of the concept of the present invention, those skilled in the art may make various modifications and alterations, and it is understood that these modifications and alterations also fall within the scope of the present invention. For example, those in which a person skilled in the art appropriately adds, deletes, or modifies components of the above-mentioned embodiments, or adds, omits, or modifies conditions of steps, are also included in the scope of the present invention as long as they include the gist of the present invention.

[0107] Furthermore, other effects and advantages brought about by the aspects of this embodiment that are obvious from the description in this specification or that can be appropriately thought of by a person skilled in the art are naturally understood to be brought about by the present invention. [Explanation of symbols]

[0108] 10, 10A, 10B, 20, 20A, 20B, 30, 30A, 30B: optical elements, 100, 100A, 100B, 200, 200A, 200B, 300, 300A, 300B: Liquid crystal cell, 110, 110A, 110B, 210, 210A, 210B, 310, 310A, 310B: substrate, 120, 120A, 120B, 220, 220A, 220B, 320, 320A, 320B: Transparent electrode, 130: alignment film, 140: sealing material, 150: liquid crystal layer, 160: optical elastic resin layer, 1000-1: 1st polarization, 1000-2: Second polarization

Claims

1. a first liquid crystal cell, a second liquid crystal cell, a third liquid crystal cell, and a fourth liquid crystal cell, which are stacked in sequence; Each of the first liquid crystal cell, the second liquid crystal cell, the third liquid crystal cell, and the fourth liquid crystal cell is a first substrate on which first transparent electrodes and second transparent electrodes extending in a direction having a first angle with respect to a first direction are alternately arranged in a second direction perpendicular to the first direction; a second substrate on which third transparent electrodes and fourth transparent electrodes extending in a direction having a second angle with respect to the second direction are alternately arranged in the first direction; a liquid crystal layer between the first substrate and the second substrate; The first angle is different from the second angle.

2. The optical element according to claim 1 , wherein the first angles of the first liquid crystal cell, the second liquid crystal cell, the third liquid crystal cell, and the fourth liquid crystal cell are different from each other.

3. In at least two of the first liquid crystal cell, the second liquid crystal cell, the third liquid crystal cell, and the fourth liquid crystal cell, the first transparent electrode and the second transparent electrode are arranged to have at least two different inter-electrode pitches; 3. The optical element according to claim 1, wherein the third transparent electrode and the fourth transparent electrode are arranged to have at least two different inter-electrode pitches.

4. The optical element of claim 3 , wherein the at least two include the second liquid crystal cell and the fourth liquid crystal cell.

5. a first liquid crystal cell, a second liquid crystal cell, a third liquid crystal cell, and a fourth liquid crystal cell, which are stacked in sequence; Each of the first liquid crystal cell, the second liquid crystal cell, the third liquid crystal cell, and the fourth liquid crystal cell is a first substrate on which first transparent electrodes extending in a direction having a first angle with respect to a first direction and bending in a direction having a second angle with respect to the first direction and second transparent electrodes extending in a direction having the second angle with respect to the first direction and bending in a direction having the first angle with respect to the first direction are alternately arranged in a second direction perpendicular to the first direction; a second substrate on which third transparent electrodes extending in a direction having a third angle with respect to the second direction and bending in a direction having a fourth angle with respect to the second direction, and fourth transparent electrodes extending in a direction having the fourth angle with respect to the second direction and bending in a direction having the third angle with respect to the second direction are alternately arranged in the first direction; a liquid crystal layer between the first substrate and the second substrate; the first angle is different from the third angle; The second angle is different from the fourth angle.

6. the first angles of the first liquid crystal cell, the second liquid crystal cell, the third liquid crystal cell, and the fourth liquid crystal cell are different from each other; The optical element according to claim 5 , wherein the second angles of the first liquid crystal cell, the second liquid crystal cell, the third liquid crystal cell, and the fourth liquid crystal cell are different from each other.

7. In at least two of the first liquid crystal cell, the second liquid crystal cell, the third liquid crystal cell, and the fourth liquid crystal cell, the first transparent electrode and the second transparent electrode are arranged to have at least two different inter-electrode pitches; 7. The optical element according to claim 5, wherein the third transparent electrode and the fourth transparent electrode are arranged to have at least two different inter-electrode pitches.

8. The optical element of claim 7 , wherein the at least two include the second liquid crystal cell and the fourth liquid crystal cell.

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