Optical element and illumination device

Abstract

An optical element (11) includes: a plurality of liquid crystal cells that includes a first liquid crystal cell (100-1) and a second liquid crystal cell (100-2) laminated on the first liquid crystal cell; and one or more light diffusion layers (170a) that overlap the plurality of liquid crystal cells. Each of the first liquid crystal cell and the second liquid crystal cell includes: a first substrate (111) in which first transparent electrodes (121) and second transparent electrodes (122) extending in a first direction are alternately and repeatedly arranged in a second direction different from the first direction; a second substrate (112) in which third transparent electrodes (123) and fourth transparent electrodes (124) extending in a third direction are alternately and repeatedly arranged in a fourth direction different from the third direction; and a first liquid crystal layer (150) between the first substrate and the second substrate. The total haze obtained by adding up the haze of at least one light diffusion layer provided outside the plurality of liquid crystal cells among the one or more light diffusion layers is 50% or more.

Description

Optical elements and lighting devices

[0001] One embodiment of the present invention relates to an optical element that uses a liquid crystal cell to control the light distribution of light emitted from a light source. Another embodiment of the present invention relates to an illumination device that irradiates light whose light distribution is controlled using a liquid crystal cell.

[0002] In recent years, lighting devices using liquid crystal cells have been developed, which utilize the refractive index distribution of the liquid crystal contained in the liquid crystal cell to diffuse or concentrate light emitted from a light source and control the light distribution (see, for example, Patent Document 1).

[0003] JP 2016-57541 A

[0004] However, in lighting devices using liquid crystal cells, the light emitted from the lighting device changes from red to blue as it moves from the center to the edge, resulting in a difference in color temperature between the center and the edge of the light. In other words, the light emitted from the lighting device may have a color due to wavelength dependency caused by the refractive index of the liquid crystal.

[0005] An object of one embodiment of the present invention is to provide an optical element that suppresses coloring of a controlled light distribution.An object of one embodiment of the present invention is to provide an illumination device that controls light distribution and emits light with suppressed coloring.

[0006] An optical element according to one embodiment of the present invention includes a plurality of liquid crystal cells, including a first liquid crystal cell and a second liquid crystal cell stacked on the first liquid crystal cell, and at least one light diffusion layer overlapping the plurality of liquid crystal cells, wherein each of the first liquid crystal cell and the second liquid crystal cell includes a first substrate on which first transparent electrodes and second transparent electrodes extending in a first direction are alternately arranged in a second direction different from the first direction, a second substrate on which third transparent electrodes and fourth transparent electrodes extending in a third direction are alternately arranged in a fourth direction different from the third direction, and a first liquid crystal layer between the first substrate and the second substrate, and wherein a total haze, which is the sum of the hazes of one or more light diffusion layers provided outside the plurality of liquid crystal cells among the at least one light diffusion layer, is 50% or more.

[0007] An optical element according to one embodiment of the present invention includes a plurality of liquid crystal cells, including a first liquid crystal cell and a second liquid crystal cell stacked on the first liquid crystal cell, and at least one light diffusing layer overlapping the plurality of liquid crystal cells, wherein each of the first liquid crystal cell and the second liquid crystal cell includes a first substrate on which first transparent electrodes and second transparent electrodes extending in a first direction are alternately and repeatedly arranged in a second direction different from the first direction, a second substrate on which third transparent electrodes and fourth transparent electrodes extending in a third direction are alternately and repeatedly arranged in a fourth direction different from the third direction, and a first liquid crystal layer between the first substrate and the second substrate, wherein the at least one light diffusing layer includes a first light diffusing layer, the first light diffusing layer including a first filler and a first adhesive, the first liquid crystal cell and the second liquid crystal cell are bonded via the first light diffusing layer, and a total haze, which is the sum of the hazes of the at least one light diffusing layer, is 50% or more.

[0008] An illumination device according to one embodiment of the present invention includes the optical element described above and a light source disposed on the first liquid crystal cell side.

[0009] 1 is a schematic perspective view showing the configuration of an illumination device according to one embodiment of the present invention; FIG. 2 is a schematic top view showing the configuration of an optical element according to one embodiment of the present invention; FIG. 3 is a schematic cross-sectional view showing the configuration of an optical element according to one embodiment of the present invention; FIG. 4 is a schematic cross-sectional view showing the configuration of an optical element according to one embodiment of the present invention; FIG. 5 is a schematic exploded plan view showing the connection configuration of transparent electrodes of a liquid crystal cell according to one embodiment of the present invention; FIG. 6 is a schematic cross-sectional view illustrating optical characteristics of a liquid crystal cell according to one embodiment of the present invention; FIG. 7 is a schematic cross-sectional view illustrating optical characteristics of a liquid crystal cell according to one embodiment of the present invention; FIG. 8 is a flowchart illustrating a method for manufacturing an optical element according to one embodiment of the present invention; FIG. 9 is a schematic side view showing the configuration of an illumination device according to one embodiment of the present invention; FIG. 10 is a schematic side view showing the configuration of an illumination device according to one embodiment of the present invention; FIG. 11 is a schematic side view showing the configuration of an illumination device according to one embodiment of the present invention; FIG. 12 is a schematic side view showing the configuration of an illumination device according to one embodiment of the present invention; FIG. 13 is a schematic perspective view showing the configuration of an illumination device according to one embodiment of the present invention; FIG. 14 is a schematic exploded plan view illustrating the extension direction of transparent electrodes of an optical element according to one embodiment of the present invention; FIG. 15 is a schematic side view showing the configuration of an illumination device according to one embodiment of the present invention; FIG. 1 is a flowchart illustrating a method for manufacturing an optical element according to one embodiment of the present invention. FIG. 2 is a schematic side view illustrating the configuration of an illumination device according to one embodiment of the present invention. FIG. 3 is a schematic side view illustrating the configuration of an illumination device according to one embodiment of the present invention. FIG. 4 is a schematic plan view illustrating a method for bonding a first liquid crystal cell and a second liquid crystal cell in an optical element according to one embodiment of the present invention. FIG. 5 is a schematic top view illustrating the configuration of a liquid crystal cell of an optical element according to one embodiment of the present invention. FIG. 6 is a schematic exploded plan view illustrating a connection configuration of transparent electrodes of a liquid crystal cell of an optical element according to one embodiment of the present invention. FIG. 7 is a schematic side view illustrating a method for bonding a first liquid crystal cell and a second liquid crystal cell in an optical element according to one embodiment of the present invention.3A and 3B are schematic side views illustrating a method for bonding a first liquid crystal cell and a second liquid crystal cell in an optical element according to one embodiment of the present invention.

[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 construed as being limited to the description of the embodiments exemplified below.

[0011] In order to clarify the explanation, the drawings may show the width, thickness, shape, etc. of each part schematically compared to the actual embodiment, but these are merely examples, and the illustrated shapes themselves do not limit the interpretation of the present invention. Furthermore, in the drawings, components having the same functions as those explained in relation to previous drawings in the specification may be given the same reference numerals even if they are different drawings, and overlapping explanations may be omitted.

[0012] Multiple components formed by processing a single film may each have different functions or roles. Furthermore, the substrates on which the multiple components are formed may be different. However, these multiple components originate from a film formed as the same layer in the same process and are made of the same material. Therefore, these multiple components are defined as existing in the same layer.

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

[0014] First Embodiment An illumination device 1 including an optical element 11 will be described with reference to FIGS.

[0015] 1 is a schematic perspective view showing the configuration of an illumination device 1 according to an embodiment of the present invention. The x-axis direction, y-axis direction, and z-axis direction shown in FIG. 1 are orthogonal to one another.

[0016] 1 , the lighting device 1 includes an optical element 11 and a light source 20. The optical element 11 and the light source 20 are arranged in the z-axis direction. In the lighting device 1, light emitted from the light source 20 is diffused or condensed by the optical element 11 while passing through the optical element 11. That is, the lighting device 1 controls the light distribution of the light emitted from the light source 20 using the optical element 11, and can irradiate light with a controlled light distribution.

[0017] The configuration of the optical element 11 will be described in detail later, but the optical element 11 includes a first liquid crystal cell 100-1, a second liquid crystal cell 100-2, and a substrate 170. Note that, hereinafter, when there is no particular distinction between the first liquid crystal cell 100-1 and the second liquid crystal cell 100-2, the first liquid crystal cell 100-1 or the second liquid crystal cell 100-2 may be referred to as the liquid crystal cell 100. In the lighting device 1, the first liquid crystal cell 100-1, the second liquid crystal cell 100-2, and the substrate 170 are stacked in order from the side closest to the light source 20. The first liquid crystal cell 100-1 and the second liquid crystal cell 100-2 are bonded together via an adhesive layer 160. The second liquid crystal cell 100-2 and the substrate 170 are also bonded together via an adhesive layer 160. A light diffusion layer 170a is provided on a surface of the substrate 170 opposite to the surface in contact with the adhesive layer 160 (hereinafter referred to as the "first surface" of the substrate 170) (hereinafter referred to as the "second surface" of the substrate 170). That is, the optical element 11 includes a light diffusion layer 170a provided on the outside of the plurality of liquid crystal cells 100. Therefore, in the lighting device 1 according to this embodiment, the light emitted from the light source 20 has its light distribution controlled by the plurality of liquid crystal cells 100, and then passes through the light diffusion layer 170a.

[0018] The light source 20 emits light toward the optical element 11 (more specifically, the first liquid crystal cell 100-1). For example, a light emitting diode (LED) can be used as the light source 20. The light source 20 may include a plurality of LEDs. Note that the light source 20 is not limited to an LED, and may be any element or device that can emit light.

[0019] 2. Configuration of Optical Element 11] Fig. 2 is a schematic top view showing the configuration of optical element 11 according to one embodiment of the present invention. For convenience of explanation, Fig. 2 shows a top view in which some of the components of optical element 11 are partially transparent. In addition, Figs. 3A and 3B are schematic cross-sectional views showing the configuration of optical element 11 according to one embodiment of the present invention. Specifically, Fig. 3A is a cross-sectional view of optical element 11 taken along line A1-A2 shown in Fig. 2, and Fig. 3B is a cross-sectional view of optical element 11 taken along line B1-B2 shown in Fig. 2.

[0020] 2, the planar shape of the optical element 11 is an octagon when viewed from above. However, the planar shape of the optical element 11 is not limited to this. The planar shape of the optical element 11 may be a polygon other than an octagon, or may be a circle or an ellipse.

[0021] 2, the second liquid crystal cell 100-2 includes a plurality of first transparent electrodes 121, a plurality of second transparent electrodes 122, a plurality of third transparent electrodes 123, and a plurality of fourth transparent electrodes for applying a voltage to the liquid crystal. A flexible printed circuit board FPC is provided at the end of the second liquid crystal cell 100-2, and is electrically connected to the first transparent electrodes 121, the second transparent electrode 122, the third transparent electrode 123, and the fourth transparent electrode. A voltage is supplied to each of the first transparent electrodes 121, the second transparent electrode 122, the third transparent electrode 123, and the fourth transparent electrode 124 via the flexible printed circuit board FPC. Note that, hereinafter, when the first transparent electrodes 121 to the fourth transparent electrodes 124 are not particularly distinguished from one another, the first transparent electrodes 121 to the fourth transparent electrodes 124 may be referred to as transparent electrodes 120.

[0022] As shown in FIG. 2 , the first transparent electrodes 121 and the second transparent electrodes 122 extend in the x-axis direction and are alternately and repeatedly arranged in the y-axis direction. The third transparent electrodes 123 and the fourth transparent electrodes 124 extend in the y-axis direction and are alternately and repeatedly arranged in the x-axis direction. As will be described in detail later, the plurality of first transparent electrodes 121 and the plurality of second transparent electrodes 122 are arranged in a comb-like shape. The plurality of third transparent electrodes 123 and the plurality of fourth transparent electrodes 124 are also arranged in a comb-like shape. While the extension direction of the transparent electrodes 120 of the second liquid crystal cell 100-2 has been described above, the extension direction of the transparent electrodes 120 of the first liquid crystal cell 100-1 is the same as the extension direction of the transparent electrodes 120 of the second liquid crystal cell 100-2.

[0023] 3A and 3B , each of the first liquid crystal cell 100-1 and the second liquid crystal cell 100-2, i.e., the liquid crystal cell 100, includes a first substrate 111, a second substrate 112, a plurality of first transparent electrodes 121, a plurality of second transparent electrodes 122, a plurality of third transparent electrodes 123, a plurality of fourth transparent electrodes 124, a first alignment film 131, a second alignment film 132, and a liquid crystal layer 150. The plurality of first transparent electrodes 121 and the plurality of second transparent electrodes 122 are provided on the first substrate 111 and covered by the first alignment film 131. The plurality of third transparent electrodes 123 and the plurality of fourth transparent electrodes 124 are provided on the second substrate 112 and covered by the second alignment film 132. The first substrate 111 and the second substrate 112 are arranged such that the first transparent electrode 121 and the second transparent electrode 122 face the third transparent electrode 123 and the fourth transparent electrode 124, and are bonded together via a sealant (not shown) provided around the periphery of the first substrate 111 and the second substrate 112. Liquid crystal is sealed in the space surrounded by the first substrate 111 (more specifically, the first alignment film 131), the second substrate 112 (more specifically, the second alignment film 132), and the sealant, and a liquid crystal layer 150 is provided between the first substrate 111 and the second substrate 112. An adhesive containing an epoxy resin or an acrylic resin is used as the sealant. The adhesive may be ultraviolet-curable or thermosetting.

[0024] For example, a rigid substrate having light-transmitting properties, such as a glass substrate, a quartz substrate, or a sapphire substrate, is used as each of the first substrate 111 and the second substrate 112. Alternatively, for example, a flexible substrate having light-transmitting properties, such as a polyimide resin substrate, an acrylic resin substrate, a siloxane resin substrate, or a fluororesin substrate, can also be used as each of the first substrate 111 and the second substrate 112.

[0025] Each of the first transparent electrode 121, the second transparent electrode 122, the third transparent electrode 123, and the fourth transparent electrode 124 functions as an electrode for forming an electric field in the liquid crystal layer 150. For example, each of the first transparent electrode 121, the second transparent electrode 122, the third transparent electrode 123, and the fourth transparent electrode 124 is made of a transparent conductive material such as indium tin oxide (ITO) or indium zinc oxide (IZO).

[0026] Each of the first alignment film 131 and the second alignment film 132 aligns the long axes of the liquid crystal molecules in the liquid crystal layer 150 in a predetermined direction. That is, when no voltage is supplied to the transparent electrode 120, the liquid crystal molecules in the liquid crystal layer 150 are oriented according to the alignment characteristics of the first alignment film 131 or the second alignment film (for convenience of explanation, the long axis direction of the liquid crystal molecules will be referred to as the alignment direction of the liquid crystal molecules below). For example, each of the first alignment film 131 and the second alignment film 132 may be made of a polyimide resin or the like. Each of the first alignment film 131 and the second alignment film 132 may be given alignment characteristics 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.

[0027] In the liquid crystal cell 100, alignment characteristics are imparted to the first alignment film 131 and the second alignment film 132 so that the alignment direction of the liquid crystal molecules is perpendicular to the extension direction of the transparent electrode 120. For ease of explanation, in Figures 3A and 3B, the alignment direction of the liquid crystal molecules in the liquid crystal layer 150 is indicated using arrows and symbols with a cross inside a circle. The arrows indicate that the alignment direction of the liquid crystal molecules is parallel to the paper surface, and the symbols with a cross inside a circle indicate that the alignment direction of the liquid crystal molecules is perpendicular to the paper surface. In the liquid crystal cell 100 according to this embodiment, the alignment direction of the liquid crystal molecules on the first substrate 111 side is the y-axis direction, and the alignment direction of the liquid crystal molecules on the second substrate 112 side is the x-axis direction.

[0028] The liquid crystal layer 150 contains liquid crystal. The liquid crystal layer 150 can refract light passing through it or change the polarization of the light passing through it depending on the orientation direction of the liquid crystal molecules in the liquid crystal. 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 a positive type, but it is also possible to apply a negative type instead of a positive type by changing the orientation direction of the liquid crystal molecules when no voltage is supplied to the transparent electrode 120. In addition, it is preferable that the liquid crystal contains a chiral agent that imparts a twist to the liquid crystal molecules.

[0029] 3A and 3B, the first liquid crystal cell 100-1 and the second liquid crystal cell 100-2 are stacked such that the second substrate 112 of the first liquid crystal cell 100-1 faces the first substrate 111 of the second liquid crystal cell 100-2. A base material 170 provided with a light diffusion layer 170a is adhered to the second substrate 112 of the second liquid crystal cell 100-2 via an adhesive layer 160.

[0030] For example, an optically transparent adhesive or the like can be used as the adhesive layer 160. The optically transparent adhesive may be in the form of a film or a liquid. In the case of a liquid optically transparent adhesive, the optically transparent adhesive is applied onto the second substrate 112 of the second liquid crystal cell 100-2, the base material 170 is attached, and then the optically transparent adhesive is cured by ultraviolet light or heat. In this way, the adhesive layer 160 is formed between the second substrate 112 of the second liquid crystal cell 100-2 and the base material 170.

[0031] For example, a rigid substrate having light-transmitting properties, such as a glass substrate, a quartz substrate, or a sapphire substrate, is used as the base material 170. Furthermore, for example, a flexible substrate having light-transmitting properties, such as a polyimide resin substrate, an acrylic resin substrate, a siloxane resin substrate, or a fluororesin substrate, can also be used as each of the first substrate 111 and the second substrate 112.

[0032] When each of the first substrate 111, the second substrate 112, and the base material 170 is a glass substrate, the base material 170 is preferably a tempered glass substrate having a higher strength than the glass substrates constituting the first substrate 111 and the second substrate 112. By using a tempered glass substrate as the base material 170, the strength of the optical element 11 can be improved and the color temperature can be increased.

[0033] The light diffusion layer 170a is provided on the second surface of the substrate 170. The light diffusion layer 170a can be formed by processing the second surface of the substrate 170 using, for example, an etching process or a sandblasting process. The light diffusion layer 170a can also be formed by providing a film on the second surface of the substrate 170. For example, the light diffusion layer 170a containing the filler can be formed by providing a film containing a filler on the second surface of the substrate 170.

[0034] The light diffusion layer 170a has an uneven surface or contains a filler therein, thereby diffusing light that passes through the light diffusion layer 170a. The light diffusion layer 170a is opaque. The haze of the light diffusion layer 170a is 50% or more, preferably 60% or more, and more preferably 70% or more. In the lighting device 1 according to this embodiment, light whose light distribution is controlled by the liquid crystal cell 100 is diffused by the light diffusion layer 170a and emitted. Therefore, the wavelength dependency of the light emitted from the lighting device 1 is reduced, and the lighting device 1 can suppress coloring of the light distribution.

[0035] In this embodiment, a configuration using a so-called anti-glare film including the adhesive layer 160 and the substrate 170 on which the light diffusion layer 170a is provided can also be applied.

[0036] 4 is a schematic exploded plan view showing the connection configuration of the transparent electrodes 120 of the liquid crystal cell 100 according to one embodiment of the present invention. While Fig. 4 is a plan view of the liquid crystal cell 100 as viewed from the top (positive z-axis direction), for ease of explanation, some of the components are omitted and the first substrate 111 and the second substrate 112 are indicated by dotted lines.

[0037] The first substrate 111 is provided with a first terminal T1 to a fourth terminal T4, a first connection electrode C1 to a fourth connection electrode C4, and a first wiring W1 to a fourth wiring W4, while the second substrate 112 is provided with a fifth terminal T5 to an eighth terminal T8, a fifth connection electrode C5 to an eighth connection electrode C8, and a fifth wiring W5 to an eighth wiring W8.

[0038] The first terminal T1 is electrically connected to the first connection electrode C1 via the first wiring W1. The second terminal T2 is electrically connected to the second connection electrode C2 via the second wiring W2. The third terminal T3 is electrically connected to the third connection electrode C3 via the third wiring W3. The fourth terminal T4 is electrically connected to the fourth connection electrode C4 via the fourth wiring W4. The fifth terminal T5 is electrically connected to the fifth connection electrode C5 via the fifth wiring W5. The sixth terminal T6 is electrically connected to the sixth connection electrode C6 via the sixth wiring W6. The seventh terminal T7 is electrically connected to the seventh connection electrode C7 via the seventh wiring W7. The eighth terminal T8 is electrically connected to the eighth connection electrode C8 via the eighth wiring W8.

[0039] Each of the first connection electrode C1 to the eighth connection electrode is an electrode for electrically connecting the wiring on the first substrate 111 side to the wiring on the second substrate 112 side. The first connection electrode C1 to the fourth connection electrode C4 are electrically connected to the fifth connection electrode C5 to the eighth connection electrode C8 via conductive members, respectively. Therefore, the first terminal T1 to the fourth terminal T4 are electrically connected to the fifth terminal T5 to the eighth terminal T8, respectively.

[0040] The first terminal T1 to the eighth terminal T8 are terminals for connecting to a flexible printed circuit board FPC (see FIGS. 1 and 2). The first terminal T1 to the fourth terminal T4 are provided at an end of the first substrate 111 and exposed from the second substrate 112. The fifth terminal T5 to the eighth terminal T8 are provided at an end of the second substrate 112 and exposed from the first substrate 111. The fifth terminal T5 to the eighth terminal T8 are provided on the opposite side to the first terminal T1 to the fourth terminal T4.

[0041] The plurality of first transparent electrodes 121 extending in the x-axis direction are electrically connected to the second wiring W2. A voltage can be supplied to the plurality of first transparent electrodes 121 via the second terminal T2 or the sixth terminal. The plurality of second transparent electrodes 122 extending in the x-axis direction are electrically connected to the third wiring W3. A voltage can be supplied to the plurality of second transparent electrodes 122 via the third terminal T3 or the seventh terminal T7. The plurality of third transparent electrodes 123 extending in the y-axis direction are electrically connected to the fifth wiring W5. A voltage can be supplied to the plurality of third transparent electrodes 123 via the first terminal T1 or the fifth terminal T5. The plurality of fourth transparent electrodes 124 extending in the y-axis direction are electrically connected to the eighth wiring W8. A voltage can be supplied to the plurality of fourth transparent electrodes 124 via the fourth terminal T4 or the eighth terminal T8.

[0042] In the liquid crystal cell 100, a voltage is supplied to the first transparent electrode 121 to the fourth transparent electrode 124 via a flexible printed circuit board FPC connected to the first terminal T1 to the fourth terminal T4 or the fifth terminal T5 to the eighth terminal T8. The flexible printed circuit board FPC may be connected to one of the first terminal T1 to the fourth terminal T4 and the fifth terminal T5 to the eighth terminal T8, or the flexible printed circuit board FPC may be connected to both the first terminal T1 to the fourth terminal T4 and the fifth terminal T5 to the eighth terminal T8.

[0043] Although the above description has been given of the optical element 11 having a configuration in which the first liquid crystal cell 100-1 and the second liquid crystal cell 100-2 are stacked in the same orientation, the optical element 11 may also have a configuration in which the second liquid crystal cell 100-2 is stacked rotated 180 degrees relative to the first liquid crystal cell 100-1. In this case, in a top view, the fifth terminal T5 to the eighth terminal T8 of the second liquid crystal cell 100-2 overlap the first terminal T1 to the fourth terminal T4 of the first liquid crystal cell 100-1, respectively. However, even in this case, the extension direction of the transparent electrodes 120 of the second liquid crystal cell 100-2 is the same as the extension direction of the transparent electrodes of the first liquid crystal cell 100-1.

[0044] 5A and 5B are schematic cross-sectional views illustrating the optical characteristics of the liquid crystal cell 100 according to one embodiment of the present invention. Specifically, Fig. 5A shows the liquid crystal cell 100 in a state where no voltage is supplied to the transparent electrode 120, and Fig. 5B shows the liquid crystal cell 100 in a state where a voltage is supplied to the transparent electrode 120.

[0045] As shown in FIG. 5A , the liquid crystal molecules on the first substrate 111 side in the liquid crystal layer 150 are aligned in the y-axis direction, and the liquid crystal molecules on the second substrate 112 side in the liquid crystal layer 150 are aligned in the x-axis direction. Therefore, when no voltage is supplied to any of the first transparent electrode 121 to the fourth transparent electrode 124, the alignment direction of the liquid crystal molecules in the liquid crystal layer 150 changes from the y-axis direction to the x-axis direction as they move from the first substrate 111 to the second substrate 112, and the alignment is twisted by 90 degrees. In this case, the polarization plane (or polarization axis) of light passing through the liquid crystal layer 150 is rotated by 90 degrees in accordance with the alignment direction of the liquid crystal molecules. In other words, the light passing through the liquid crystal layer 150 is optically rotated. Specifically, of the light incident on the first substrate 111, a first polarized component 1000-1 having a polarization axis in the x-axis direction has its polarization axis rotated by 90 degrees when passing through the liquid crystal cell 100, and is emitted from the second substrate 112 with its polarization axis in the y-axis direction. Furthermore, of the light incident on the first substrate 111, a second polarized component 1000-2 having a polarization axis in the y-axis direction has its polarization axis rotated by 90 degrees when passing through the liquid crystal cell 100, and is emitted from the second substrate 112 with its polarization axis in the x-axis direction.

[0046] As shown in FIG. 5B , when different voltages are applied to two adjacent transparent electrodes 120, a potential difference is generated between the two adjacent transparent electrodes 120, generating an electric field (hereinafter referred to as a "transverse electric field") between the two adjacent transparent electrodes 120. In this case, the orientation state of the liquid crystal molecules in the liquid crystal layer 150 changes due to the influence of the transverse electric field. Specifically, the liquid crystal molecules in the liquid crystal layer 150 are oriented so as to be twisted 90 degrees as they move from the first substrate 111 toward the second substrate 112. The liquid crystal molecules on the first substrate 111 side are oriented in a convex arc shape in the y-axis direction by the transverse electric field between the first transparent electrode 121 and the second transparent electrode 122, while the liquid crystal molecules on the second substrate 112 side are oriented in a convex arc shape in the x-axis direction by the transverse electric field between the third transparent electrode 123 and the fourth transparent electrode 124. The liquid crystal molecules oriented in a convex arc shape have a refractive index distribution, and polarized components of light having a polarization axis in the same direction as the orientation direction of the liquid crystal molecules are diffused. Specifically, the first polarized component 1000-1 has a polarization axis that is oriented in a direction different from the alignment direction of the liquid crystal molecules on the first substrate 111 side and the second substrate 112 side, and therefore the first polarized component 1000-1 is not diffused on the first substrate 111 side and the second substrate 112 side. On the other hand, the second polarized component 1000-2 has a polarization axis that is oriented in the same direction as the alignment direction of the liquid crystal molecules on the first substrate 111 side and the second substrate 112 side, and therefore the second polarized component 1000-2 is diffused on the first substrate 111 side and the second substrate 112 side.

[0047] The cell gap d, which is the distance between the first substrate 111 and the second substrate 112, is sufficiently larger than the distance between two adjacent transparent electrodes 120 (for example, 8 μm≦d≦50 μm, preferably 10 μm≦d≦30 μm, and more preferably 15 μm≦d≦25 μm). Therefore, the transverse electric field generated on the first substrate 111 side and the second substrate 112 side has almost no effect on the liquid crystal molecules located near the center between the first substrate 111 and the second substrate 112.

[0048] As described above, in the liquid crystal cell 100, the orientation of the liquid crystal molecules in the liquid crystal layer 150 can be changed by the voltage supplied to the transparent electrode 120, thereby controlling the diffusion of light passing through the liquid crystal cell 100. In the lighting device 1, the voltage supplied to the transparent electrodes 120 of the two liquid crystal cells 100 included in the optical element 11 is controlled. This allows the lighting device 1 to emit light with various light distributions.

[0049] 6 is a flowchart illustrating a method for manufacturing the optical element 11 according to one embodiment of the present invention. As shown in FIG. 6, the method for manufacturing the optical element 11 includes steps S100 to S130. Each step will be described in order below, but the method for manufacturing the optical element 11 may include steps other than steps S100 to S130.

[0050] In step S100, a first liquid crystal cell 100-1 and a second liquid crystal cell 100-2 included in the optical element 11 are fabricated. That is, in step S100, a plurality of liquid crystal cells 100 having the same structure are fabricated. Specifically, a first alignment film 131 is applied so as to cover the first transparent electrode 121 and the second transparent electrode 122 formed on the first substrate 111. Furthermore, a second alignment film 132 is applied so as to cover the third transparent electrode 123 and the fourth transparent electrode 124 formed on the second substrate 112. Thereafter, a sealant is applied to the periphery of the first substrate 111 or the second substrate 112, and then liquid crystal is injected between the first substrate 111 and the second substrate 112, and the first substrate 111 and the second substrate 112 are bonded together. In this way, the first substrate 111 and the second substrate 112 are bonded together by the sealant, and the liquid crystal cell 100 is fabricated.

[0051] In step S110, a substrate 170 provided with a light diffusion layer 170a is prepared separately from the preparation of the liquid crystal cell 100. Specifically, an etching process or a sandblasting process is performed on the second surface of the substrate 170 to form the light diffusion layer 170a on the second surface of the substrate 170. Alternatively, a film containing a filler may be applied onto the second surface of the substrate 170 to form the light diffusion layer 170a on the second surface of the substrate 170.

[0052] In step S120, the first liquid crystal cell 100-1 and the second liquid crystal cell 100-2 prepared in step S100 are bonded together. Specifically, an optically transparent adhesive is applied as an adhesive layer 160 onto the second substrate 112 of the first liquid crystal cell 100-1, or an optically transparent adhesive film is attached, and then the first liquid crystal cell 100-1 and the second liquid crystal cell 100-2 are bonded together so that the second substrate 112 of the first liquid crystal cell 100-1 and the first substrate 111 of the second liquid crystal cell 100-2 face each other. This bonds the first liquid crystal cell 100-1 and the second liquid crystal cell 100-2 together via the adhesive layer 160.

[0053] In step S130, the second liquid crystal cell 100-2, which has been bonded to the first liquid crystal cell 100-1 in step S120, is bonded to the substrate 170 provided with the light diffusion layer 170a produced in step S110. Specifically, an optically transparent adhesive is applied as the adhesive layer 160 onto the second substrate 112 of the second liquid crystal cell 100-2, or an optically transparent adhesive film is attached, and then the second liquid crystal cell 100-2 and the substrate 170 are bonded together so that the second substrate 112 of the second liquid crystal cell 100-2 and the first surface of the substrate 170 face each other. This bonds the second liquid crystal cell 100-2 and the substrate 170 via the adhesive layer 160.

[0054] Although the optical element 11 can be manufactured by the above-described manufacturing method, the manufacturing method of the optical element 11 is not limited to this. For example, in step S130, the optical element 11 can also be manufactured by attaching an anti-glare film composed of the adhesive layer 160, the base material 170, and the light diffusion layer 170a to the second substrate 112 of the second liquid crystal cell 100-2.

[0055] According to this embodiment, the light whose light distribution has been controlled while passing through the plurality of liquid crystal cells 100 is diffused when passing through the light diffusion layer 170a. Therefore, the irregularity of the direction of the light emitted from the lighting device 1 increases, and as a result, coloring of the light distribution can be suppressed.

[0056] 7, a description will be given of an illumination device 1A that is a modification of the illumination device 1. Note that, in the following, a description of the configuration of the illumination device 1A that is similar to the configuration of the illumination device 1 may be omitted.

[0057] 7 is a schematic side view showing the configuration of an illumination device 1A according to one embodiment of the present invention. The illumination device 1A includes an optical element 11A and a light source 20.

[0058] 7, in the optical element 11A, a substrate 170, a first liquid crystal cell 100-1, and a second liquid crystal cell 100-2 are stacked in order from the side closest to the light source 20. That is, a light diffusion layer 170a provided on the substrate 170 faces the light source 20. Therefore, in the lighting device 1A according to this modification, the light emitted from the light source 20 passes through the light diffusion layer 170a, and then the light distribution is controlled by the multiple liquid crystal cells 100.

[0059] According to this modification, the light emitted from the light source 20 is diffused by the light diffusion layer 170a and can be incident on the first liquid crystal cell 100-1 from various directions. Therefore, the irregularity of the direction of the light passing through the optical element 11A increases, and the irregularity of the direction of the light emitted from the lighting device 1A also increases, resulting in suppression of coloring of the light distribution.

[0060] <Second Modification of First Embodiment> With reference to Fig. 8 , a description will be given of an illumination device 1B which is another modification of the illumination device 1. Note that, in the following, description of the configuration of the illumination device 1B which is similar to the configuration of the illumination device 1 may be omitted.

[0061] 8 is a schematic side view showing the configuration of an illumination device 1B according to one embodiment of the present invention. The illumination device 1B includes an optical element 11B and a light source 20.

[0062] As shown in FIG. 8 , the optical element 11B includes two substrates 170. One of the two substrates 170 is bonded to the first liquid crystal cell 100-1 via an adhesive layer 160. The other of the two substrates 170 is bonded to the second liquid crystal cell 100-2 via an adhesive layer 160. A light diffusion layer 170a is provided on each of the two substrates 170. That is, the optical element 11B includes light diffusion layers 170a provided on both outer sides of the plurality of liquid crystal cells 100. Therefore, in the lighting device 1B according to this modification, light emitted from the light source 20 passes through one light diffusion layer 170a, has its light distribution controlled by the plurality of liquid crystal cells 100, and then passes through the other light diffusion layer 170a.

[0063] When the optical element 11 includes two spaced apart light diffusion layers 170a as in this modified example, the total haze obtained by adding up the haze of the two light diffusion layers 170a is 50% or more, preferably 60% or more, and more preferably 70% or more.

[0064] According to this modification, light emitted from the light source 20 is diffused by the light diffusion layer 170a and can be incident on the first liquid crystal cell 100-1 from various directions. Furthermore, the light whose light distribution has been controlled while passing through the plurality of liquid crystal cells 100 is diffused when passing through the light diffusion layer 170a. Therefore, the irregularity of the direction of the light emitted from the lighting device 1B increases, and as a result, coloring of the light distribution can be suppressed.

[0065] 9 , a description will be given of an illumination device 1C that is another modification of the illumination device 1. Note that, in the following, a description of the configuration of the illumination device 1C that is similar to the configuration of the illumination device 1 may be omitted.

[0066] 9 is a schematic side view showing the configuration of an illumination device 1C according to one embodiment of the present invention. The illumination device 1C includes an optical element 11C and a light source 20.

[0067] 9 , the optical element 11C includes, in order from the side closest to the light source, a first liquid crystal cell 100-1, a second liquid crystal cell 100-2, a third liquid crystal cell 100-3, a fourth liquid crystal cell 100-4, and a substrate 170 stacked thereon. The third liquid crystal cell 100-3 and the fourth liquid crystal cell 100-4 have the same configuration as the first liquid crystal cell 100-1 and the second liquid crystal cell 100-2. However, the third liquid crystal cell 100-3 and the fourth liquid crystal cell 100-4 differ from the first liquid crystal cell 100-1 and the second liquid crystal cell 100-2 in the extending direction of the transparent electrodes 120. In each of the third liquid crystal cell 100-3 and the fourth liquid crystal cell 100-4, the first transparent electrodes 121 and the second transparent electrodes 122 extend in the y-axis direction and are alternately arranged in the x-axis direction. The third transparent electrodes 123 and the fourth transparent electrodes 124 extend in the x-axis direction and are alternately arranged in the y-axis direction. That is, the third liquid crystal cell 100-3 and the fourth liquid crystal cell 100-4 are stacked at a 90-degree angle with respect to the first liquid crystal cell 100-1 and the second liquid crystal cell 100-2.

[0068] In the optical element 11C, the number of times that light passing through the optical element 11C is diffused or concentrated increases due to the increased number of liquid crystal cells 100. Therefore, the lighting device 1C can control even more types of light distribution.

[0069] The number of liquid crystal cells 100 in the optical element 11C is not limited to four. The number of liquid crystal cells 100 may be three, or may be five or more.

[0070] According to this modification, the light whose light distribution has been controlled while passing through the liquid crystal cells 100 is diffused when passing through the light diffusion layer 170a. This increases the irregularity in the direction of the light emitted from the lighting device 1C, thereby suppressing coloring of the light distribution.

[0071] 10 and 11 , an illumination device 2 including an optical element 12 will be described. Note that, in the following, description of the configuration of the illumination device 2 that is similar to the configuration of the illumination device 1 may be omitted.

[0072] 10 is a schematic side view showing the configuration of an illumination device 2 according to an embodiment of the present invention. The illumination device 2 includes an optical element 12 and a light source 20.

[0073] 10 , in the optical element 12, a first liquid crystal cell 100-1 and a second liquid crystal cell 100-2 are stacked in order from the side closest to the light source 20. The first liquid crystal cell 100-1 and the second liquid crystal cell 100-2 are bonded together via an adhesive layer 160. A light diffusion layer 111a is provided on the outer surface of the first substrate 111 of the liquid crystal cell 100. Furthermore, a light diffusion layer 112a is provided on the outer surface of the second substrate 112 of the liquid crystal cell 100. Therefore, the adhesive layer 160 is in contact with the light diffusion layer 112a provided on the second substrate 112 of the first liquid crystal cell 100-1 and the light diffusion layer 112a provided on the first substrate 111 of the second liquid crystal cell 100-2. On the other hand, the light diffusion layer 111a provided on the first substrate 111 of the first liquid crystal cell 100-1 and the light diffusion layer 112a provided on the second substrate 112 of the second liquid crystal cell 100-2 are exposed. That is, the optical element 12 includes the light diffusion layer 111a and the light diffusion layer 112a provided on both outer sides of the plurality of liquid crystal cells 100. Therefore, in the lighting device 2 according to this embodiment, the light emitted from the light source 20 passes through the light diffusion layer 111a that is not in contact with the adhesive layer 160, and then has its light distribution controlled by the plurality of liquid crystal cells 100, and passes through the light diffusion layer 112a that is not in contact with the adhesive layer 160.

[0074] The light diffusion layer 111a and the light diffusion layer 112a are respectively formed directly on the first substrate 111 and the second substrate 112. The light diffusion layer 111a and the light diffusion layer 112a can be formed by processing the outer surfaces of the first substrate 111 and the second substrate 112 using, for example, an etching process or a sandblasting process.

[0075] The light diffusion layers 111a and 112a have unevenness and function to diffuse light that passes through them. However, if the light diffusion layers 111a and 112a come into contact with the adhesive layer 160, the light diffusion function of the light diffusion layers 111a and 112a will be reduced or lost. Therefore, in the optical element 12, the light diffusion layers 111a and 112a, which are provided on both outer sides of the multiple liquid crystal cells 100 and do not come into contact with the adhesive layer 160, have the effect of suppressing coloring of the light distribution. The light diffusion layers 111a and 112a, which do not come into contact with the adhesive layer 160, are opaque. Therefore, in the optical element 12, the total haze, which is the sum of the hazes of the light diffusion layers 111a and 112a provided on both outer sides of the multiple liquid crystal cells 100, is 50% or more, preferably 60% or more, and more preferably 70% or more.

[0076] 11 is a flowchart illustrating a method for manufacturing the optical element 12 according to one embodiment of the present invention. As shown in FIG. 11, the method for manufacturing the optical element 12 includes steps S200 to S240. Each step will be described in order below, but the method for manufacturing the optical element 12 may include steps other than steps S200 to S240.

[0077] In step S200, a first electrode pattern including a first transparent electrode 121 and a second transparent electrode 122 and a second electrode pattern including a third transparent electrode 123 and a fourth transparent electrode 124 are formed on one surface of a large-area substrate (e.g., mother glass). The first electrode pattern and the second electrode pattern are formed in different regions.

[0078] In step S210, the other surface of the large-area substrate is subjected to surface treatment. Specifically, the other surface of the large-area substrate is subjected to etching or sandblasting. As a result, a light diffusion layer is formed on the other surface of the large-area substrate.

[0079] In step S220, the large-area substrate is divided. Specifically, the large-area substrate is divided so that the region where the first electrode pattern is formed and the region where the second electrode pattern is formed are separated. This produces a first substrate 111 on which the first electrode pattern, i.e., the first transparent electrode 121 and the second transparent electrode 122, is formed, and a second substrate 112 on which the second electrode pattern, i.e., the third transparent electrode 123 and the fourth transparent electrode 124, is formed. Because a light diffusion layer is formed on the other surface of the large-area substrate in step S210, the first substrate 111 and the second substrate 112 produced in step S220 each include a surface on which the light diffusion layer 111a and the light diffusion layer 112a are formed.

[0080] In step S230, the first liquid crystal cell 100-1 and the second liquid crystal cell 100-2 included in the optical element 11 are fabricated. Step S230 is similar to step S100 described in the first embodiment, and therefore a description thereof will be omitted here.

[0081] In step S240, the first liquid crystal cell 100-1 and the second liquid crystal cell 100-2 prepared in step S230 are bonded together. Step S240 is the same as step S120 described in the first embodiment, and therefore will not be described here.

[0082] Although the optical element 12 can be manufactured by the above-described manufacturing method, the manufacturing method of the optical element 12 is not limited to this. For example, in step S200, two large-area substrates may be used, and a first electrode pattern may be formed on one large-area substrate and a second electrode pattern may be formed on the other large-area substrate. In this case, a first substrate 111 on which a first transparent electrode 121 and a second transparent electrode 122 are formed is manufactured from one large-area substrate, and a second substrate 112 on which a third transparent electrode 123 and a fourth transparent electrode 124 are formed is manufactured from the other large-area substrate.

[0083] According to this embodiment, light emitted from the light source 20 is diffused by the light diffusion layer 111a that is not in contact with the adhesive layer 160, and can be incident on the first liquid crystal cell 100-1 from various directions. Furthermore, the light whose light distribution has been controlled while passing through the plurality of liquid crystal cells 100 is diffused when passing through the light diffusion layer 112a that is not in contact with the adhesive layer 160. Therefore, the irregularity in the direction of the light emitted from the lighting device 2 increases, and as a result, coloring of the light distribution can be suppressed.

[0084] 12 , a description will be given of an illumination device 2A that is a modification of the illumination device 2. Note that, in the following, a description of the configuration of the illumination device 2A that is similar to the configuration of the illumination device 2 may be omitted.

[0085] 12 is a schematic side view showing the configuration of an illumination device 2A according to one embodiment of the present invention. The illumination device 2A includes an optical element 12A and a light source 20.

[0086] As shown in FIG. 12 , in the optical element 12A, a light diffusion layer 112a is provided only on the second substrate 112 of the liquid crystal cell 100. The light diffusion layer 112a provided on the second substrate 112 of the first liquid crystal cell 100-1 is in contact with the adhesive layer 160. Therefore, although the light diffusion layer 112a provided on the second substrate 112 of the first liquid crystal cell 100-1 has an uneven surface, it has almost no light diffusion function. In the optical element 12A, the light diffusion layer 112a provided on the second substrate 112 of the second liquid crystal cell 100-2, which is not in contact with the adhesive layer 160, has the effect of suppressing coloring of the light distribution. Therefore, in the optical element 12A, the haze of the light diffusion layer 112a provided on the outer side of the multiple liquid crystal cells 100 is 50% or more, preferably 60% or more, and more preferably 70% or more.

[0087] According to this modification, the light whose light distribution has been controlled while passing through the plurality of liquid crystal cells 100 is diffused when passing through the light diffusion layer 112a that is not in contact with the adhesive layer 160. Therefore, the irregularity in the direction of the light emitted from the lighting device 2 increases, and as a result, coloring of the light distribution can be suppressed.

[0088] 13 and 14 , a description will be given of an illumination device 2B that is another modification of the illumination device 2. Note that, in the following, a description of the configuration of the illumination device 2B that is similar to the configuration of the illumination device 2 may be omitted.

[0089] Fig. 13 is a schematic side view showing the configuration of an illumination device 2B according to an embodiment of the present invention. Fig. 14 is a schematic perspective view showing the configuration of an illumination device 2B according to an embodiment of the present invention. The illumination device 2B includes an optical element 12B and a light source 20.

[0090] 13, in the optical element 12B, a first liquid crystal cell 100-1 and a second liquid crystal cell 100-2 are stacked in order from the side closest to the light source. The stacking order of the liquid crystal cells 100 in the optical element 12B is the same as the stacking order of the liquid crystal cells 100 in the optical element 12A. However, the orientation of the second liquid crystal cell 100-2 in the optical element 12B is different from that in the optical element 12A. In the optical element 12B, the first liquid crystal cell 100-1 and the second liquid crystal cell 100-2 are bonded via an adhesive layer 160 so that the second substrate 112 of the first liquid crystal cell 100-1 and the second substrate 112 of the second liquid crystal cell 100-2 face each other. In addition, in the optical element 12B, the first substrate 111 and the second substrate 112 of the second liquid crystal cell 100-2 are not only inverted and stacked on top of the first liquid crystal cell 100-1, but are also rotated 180 degrees relative to the first liquid crystal cell 100-1, as shown in Figure 14.

[0091] FIG. 14 shows two flexible printed circuit boards FPC: a flexible printed circuit board FPC1 connected to the first liquid crystal cell 100-1, and a flexible printed circuit board FPC2 connected to the second liquid crystal cell 100-2. The flexible printed circuit board FPC1 is electrically connected to the first terminal T1 to the fourth terminal T4 provided on the first substrate 111 of the first liquid crystal cell 100-1. Meanwhile, the flexible printed circuit board FPC2 is electrically connected to the fifth terminal T5 to the eighth terminal T8 provided on the second substrate 112 of the second liquid crystal cell 100-2. As shown in FIG. 14, in the optical element 12B, two flexible printed circuit boards FPC can be connected at one end surface side. This simplifies the mounting of the optical element 12B.

[0092] In addition, in the optical element 12B, the extension direction of the first transparent electrode 121 and the second transparent electrode 122 may not be parallel to the x-axis direction, and the extension direction of the third transparent electrode 123 and the fourth transparent electrode 124 may not be parallel to the y-axis direction. Here, with reference to Fig. 15 , a case where the extension direction of the transparent electrode 120 is not the x-axis direction or the y-axis direction will be described.

[0093] Fig. 15 is a schematic exploded plan view showing the extension direction of the transparent electrode 120 of the optical element 12B according to one embodiment of the present invention. Fig. 15 is a plan view of the optical element 12B as viewed from above (the +z-axis direction). For ease of explanation, some of the components are omitted, and the first substrate 111 and the second substrate 112 are indicated by dotted lines.

[0094] 15 , on the first substrate 111 of the first liquid crystal cell 100-1, the extension directions of the first transparent electrode 121 and the second transparent electrode 122 are in a direction that forms a first positive angle (+θ1) with respect to the x-axis direction. On the other hand, on the second substrate 112 of the first liquid crystal cell 100-1, the extension directions of the third transparent electrode 123 and the fourth transparent electrode 124 are in a direction that forms a second positive angle (+θ2) with respect to the y-axis direction. As described above, in the second liquid crystal cell 100-2, the first substrate 111 and the second substrate 112 are inverted upside down and are further rotated 180 degrees with respect to the first liquid crystal cell 100-1. 15 , on the second substrate 112 of the second liquid crystal cell 100-2, the extension directions of the third transparent electrode 123 and the fourth transparent electrode 124 are in a direction that forms a negative second angle (−θ2) with respect to the y-axis direction. On the first substrate 111 of the second liquid crystal cell 100-2, the extension directions of the first transparent electrode 121 and the second transparent electrode 122 are in a direction that forms a negative second angle (−θ1) with respect to the x-axis direction. Here, the first angle θ1 and the second angle θ2 are each 1 degree or greater, preferably 2 degrees or greater, and more preferably 3 degrees or greater. The upper limits of the first angle θ1 and the second angle θ2 are not particularly limited, but may be, for example, 15 degrees or less, 10 degrees or less, or 5 degrees or less.

[0095] As described above, in the optical element 12B, not only the extending directions of the transparent electrodes 120 on the first substrate 111 and the second substrate 112 of the first liquid crystal cell 100-1 but also the extending directions of the transparent electrodes 120 on the second substrate 112 and the first substrate 111 of the second liquid crystal cell 100-2 are different. Therefore, the interference effect of light passing through the optical element 12B is suppressed, and moire can be reduced.

[0096] According to this modification, light emitted from the light source 20 is diffused by the light diffusion layer 111a and can be incident on the first liquid crystal cell 100-1 from various directions. Furthermore, the light whose light distribution has been controlled while passing through the plurality of liquid crystal cells 100 is diffused when passing through the light diffusion layer 112a. Therefore, the irregularity of the direction of the light emitted from the lighting device 2B increases, and as a result, coloring of the light distribution can be suppressed.

[0097] 16 and 17 , an illumination device 3 including an optical element 13 will be described. Note that, in the following, a description of the configuration of the illumination device 3 that is similar to the configuration of the illumination device 1 or the illumination device 2 may be omitted.

[0098] 16 is a schematic side view showing the configuration of an illumination device 3 according to an embodiment of the present invention. The illumination device 3 includes an optical element 13 and a light source 20.

[0099] 16, in the optical element 13, a first liquid crystal cell 100-1 and a second liquid crystal cell 100-2 are stacked in order from the side closest to the light source. A light diffusion layer 160a is disposed between the first liquid crystal cell 100-1 and the second liquid crystal cell 100-2. The light diffusion layer 160a contains a filler and an adhesive. Therefore, the first liquid crystal cell 100-1 and the second liquid crystal cell 100-2 are bonded together via the light diffusion layer 160a.

[0100] As described above, the light diffusion layer 160a contains an adhesive and therefore has an adhesive function. Furthermore, the light diffusion layer 160a contains a filler, which can diffuse light passing through the light diffusion layer 160a. Unlike the light diffusion layers 170a, 111a, and 112a, the light diffusion layer 160a has a filler mixed in the adhesive that has a light diffusion function. Therefore, the light diffusion layer 160a can have a light diffusion function not only outside the plurality of liquid crystal cells 100 but also when disposed between the plurality of liquid crystal cells 100. In the optical element 13, the haze of the light diffusion layer 160a is 50% or more, preferably 60% or more, and more preferably 70% or more. In this embodiment, the light diffusion layer 160a of the optical element 13 diffuses light, reducing the wavelength dependency of light emitted from the lighting device 3, thereby suppressing coloring of the light distribution in the lighting device 3.

[0101] 17 is a flowchart illustrating a method for manufacturing the optical element 13 according to one embodiment of the present invention. As shown in FIG. 17, the method for manufacturing the optical element 13 includes steps S300 to S320. Each step will be described in order below, but the method for manufacturing the optical element 13 may include steps other than steps S300 to S320.

[0102] In step S300, a first liquid crystal cell 100-1 and a second liquid crystal cell 100-2 are fabricated to be included in the optical element 13. Step S300 is similar to step S100 described in the first embodiment, and therefore a description thereof will be omitted here.

[0103] In step S310, a light diffusion layer 160a having an adhesive function is formed on the second substrate 112 of the first liquid crystal cell 100-1. Specifically, a film containing a filler and an adhesive is applied to the second substrate 112 of the first liquid crystal cell 100-1 to form the light diffusion layer 160a. Alternatively, the light diffusion layer 160a may be formed by attaching an optically transparent adhesive film containing a filler and an adhesive to the second substrate 112 of the first liquid crystal cell 100-1.

[0104] In step S320, the first liquid crystal cell 100-1 and the second liquid crystal cell 100-2 are bonded together so that the second substrate 112 of the first liquid crystal cell 100-1 faces the first substrate 111 of the second liquid crystal cell 100-2. As a result, the first liquid crystal cell 100-1 and the second liquid crystal cell 100-2 are bonded together with the light diffusion layer 160a interposed therebetween, and the optical element 13 is manufactured.

[0105] According to this embodiment, the light emitted from the light source 20 has its light distribution controlled while passing through the liquid crystal cells 100, and is diffused when passing through the light diffusion layer 160a. Therefore, the irregularity of the direction of the light emitted from the lighting device 3 increases, and as a result, coloring of the light distribution can be suppressed.

[0106] 18 , a description will be given of an illumination device 3A that is a modification of the illumination device 3. Note that, in the following, a description of the configuration of the illumination device 3A that is similar to the configuration of the illumination device 3 may be omitted.

[0107] 18 is a schematic side view showing the configuration of an illumination device 3A according to one embodiment of the present invention. The illumination device 3A includes an optical element 13A and a light source 20.

[0108] As shown in FIG. 18 , the optical element 13A includes a first liquid crystal cell 100-1, a second liquid crystal cell 100-2, and a substrate 170 stacked in order from the side closest to the light source 20. The first liquid crystal cell 100-1 and the second liquid crystal cell 100-2 are bonded together via a light diffusion layer 160a. The second liquid crystal cell 100-2 and the substrate 170 are also bonded together via a light diffusion layer 160a. In the optical element 13A, each of the two light diffusion layers 160a has the effect of suppressing coloring of the light distribution. Therefore, in the optical element 13A, the total haze, which is the sum of the hazes of the two light diffusion layers 160a, is 50% or more, preferably 60% or more, and more preferably 70% or more.

[0109] The light diffusion layer 160a and the substrate 170 provided on the second liquid crystal cell 100-2 may be configured as a single member such as a so-called anti-glare film.

[0110] Furthermore, since the base material 170 is provided on the outside of the optical element 13A, the base material 170 protects the optical element 13A.

[0111] According to this modification, the light emitted from the light source 20 has its light distribution controlled while passing through the plurality of liquid crystal cells 100, and is diffused when passing through the plurality of light diffusion layers 160a. Therefore, the irregularity of the direction of the light emitted from the lighting device 3A increases, and as a result, coloring of the light distribution can be suppressed.

[0112] The optical element 13A may also be configured to have multiple light diffusion layers 160a between the first liquid crystal cell 100-1 and the second liquid crystal cell 100-2, or between the second liquid crystal cell 100-2 and the substrate 170. Even in this case, the total haze, which is the sum of the hazes of the multiple light diffusion layers 160a included in the optical element 13A, is 50% or more, preferably 60% or more, and more preferably 70% or more. By providing multiple light diffusion layers 160a, the haze of each light diffusion layer 160a can be reduced.

[0113] 19 , a description will be given of an illumination device 3B, which is another modification of the illumination device 3. Note that, in the following, a description of the configuration of the illumination device 3B that is similar to the configuration of the illumination device 3 may be omitted.

[0114] 19 is a schematic side view showing the configuration of an illumination device 3B according to one embodiment of the present invention. The illumination device 3B includes an optical element 13B and a light source 20.

[0115] As shown in FIG. 19 , in the optical element 13B, a first liquid crystal cell 100-1, a second liquid crystal cell 100-2, and a substrate 170 are stacked in order from the side closest to the light source 20. The first liquid crystal cell 100-1 and the second liquid crystal cell 100-2 are bonded via a light diffusion layer 160a. The second liquid crystal cell 100-2 and the substrate 170 are bonded via an adhesive layer 160. A light diffusion layer 170a is provided on the second surface of the substrate 170. In the optical element 13B, the light diffusion layer 160a and the light diffusion layer 170a have the effect of suppressing coloring of the light distribution. Therefore, in the optical element 13B, the total haze, which is the sum of the hazes of the light diffusion layer 160a and the light diffusion layer 170a, is 50% or more, preferably 60% or more, and more preferably 70% or more.

[0116] The adhesive layer 160, the substrate 170, and the light diffusion layer 170a provided on the second liquid crystal cell 100-2 may be configured as a single member such as a so-called anti-glare film.

[0117] According to this modification, the light emitted from the light source 20 has its light distribution controlled while passing through the plurality of liquid crystal cells 100, and is diffused when passing through the light diffusion layers 160 a and 170 a. Therefore, the irregularity in the direction of the light emitted from the lighting device 3B increases, and as a result, coloring of the light distribution can be suppressed.

[0118] 20 , a description will be given of an illumination device 3C that is another modification of the illumination device 3. Note that, in the following, a description of the configuration of the illumination device 3C that is similar to the configuration of the illumination device 3 may be omitted.

[0119] 20 is a schematic side view showing the configuration of an illumination device 3C according to one embodiment of the present invention. The illumination device 3C includes an optical element 13C and a light source 20.

[0120] 20, in optical element 13C, a first liquid crystal cell 100-1, a second liquid crystal cell 100-2, a third liquid crystal cell 100-3, a fourth liquid crystal cell 100-4, and a substrate 170 are stacked in order from the side closest to the light source. The third liquid crystal cell 100-3 and the fourth liquid crystal cell 100-4 are stacked and rotated 90 degrees with respect to the first liquid crystal cell 100-1 and the second liquid crystal cell 100-2.

[0121] The first liquid crystal cell 100-1 and the second liquid crystal cell 100-2 are bonded together via a light diffusion layer 160a. The second liquid crystal cell 100-2 and the third liquid crystal cell 100-3 are also bonded together via a light diffusion layer 160a. The third liquid crystal cell 100-3 and the fourth liquid crystal cell 100-4 are also bonded together via a light diffusion layer 160a. The fourth liquid crystal cell 100-4 and the substrate 170 are bonded together via an adhesive layer 160. In the optical element 13C, the three light diffusion layers 160a and the light diffusion layer 170a have the effect of suppressing coloring of the light distribution. Therefore, in the optical element 13C, the total haze, which is the sum of the hazes of the three light diffusion layers 160a and the light diffusion layer 170a, is 50% or more, preferably 60% or more, and more preferably 70% or more.

[0122] In the optical element 13C, the number of light diffusion layers 160a can be increased, and therefore the haze of each light diffusion layer 160a can be reduced.

[0123] According to this modification, the light emitted from the light source 20 has its light distribution controlled while passing through the plurality of liquid crystal cells 100, and is diffused when passing through the three light diffusion layers 160 a and 170 a. Therefore, the irregularity in the direction of the light emitted from the lighting device 3B increases, and as a result, coloring of the light distribution can be suppressed.

[0124] Fourth Embodiment The optical element 11 described in the first embodiment, the optical element 12 described in the second embodiment, and the optical element 13 described in the third embodiment each have at least one light diffusion layer with high haze. Because a light diffusion layer with high haze is opaque, it may be difficult to read a marker for alignment during the bonding process. When the light diffusion layer is partially provided, alignment using the marker is possible by placing the marker in a translucent region that does not overlap with the light diffusion layer in a planar view. However, in the optical element 12, optical element 12A, and optical element 12B described in the second embodiment, the light diffusion layer 111a or the light diffusion layer 112a is formed on the first substrate 111 or the second substrate 112, making it difficult to partially provide the light diffusion layer 111a or the light diffusion layer 112a. Therefore, below, using optical element 12, optical element 12A, and optical element 12B as examples, we will explain a method of bonding first liquid crystal cell 100-1 and second liquid crystal cell 100-2 when a light diffusion layer 111a or a light diffusion layer 112a is provided on the entire surface of first substrate 111 or second substrate 112.

[0125] [1. Method for bonding the first liquid crystal cell 100-1 and the second liquid crystal cell 100-2 in the optical element 12] FIG. 21 is a schematic plan view illustrating a method for bonding the first liquid crystal cell 100-1 and the second liquid crystal cell 100-2 in the optical element 12 according to one embodiment of the present invention.

[0126] In the optical element 12, a light diffusion layer 111a and a light diffusion layer 112a are provided on the first substrate 111 and the second substrate 112 of the liquid crystal cell 100, respectively (see FIG. 10). That is, the optical element 12 includes a light diffusion layer 111a and a light diffusion layer 112a having high haze that are provided on the outer surfaces of the optical element 12. In the optical element 12, the first liquid crystal cell 100-1 and the second liquid crystal cell 100-2 can be bonded together using an alignment jig 500, as shown in FIG.

[0127] In a plan view, the first liquid crystal cell 100-1 and the second liquid crystal cell 100-2 have an octagonal shape. In addition, in a top view, the second liquid crystal cell 100-2 has at least two end faces that coincide with those of the first liquid crystal cell 100-1. The alignment jig 500 includes a first wall surface 501 and a second wall surface 502, and has a "L" shape in which the first wall surface 501 and the second wall surface 502 are connected. The angle formed by the first wall surface 501 and the second wall surface 502 not only coincides with the angle formed by the two end faces of the first liquid crystal cell 100-1, but also coincides with the angle formed by the two end faces of the second liquid crystal cell 100-2. Therefore, when two end faces of the first liquid crystal cell 100-1 and two end faces of the second liquid crystal cell 100-2 are brought into contact with the first wall surface 501 and the second wall surface 502 of the alignment jig 500, the first liquid crystal cell 100-1 and the second liquid crystal cell 100-2 are aligned in a top view. That is, the first liquid crystal cell 100-1 and the second liquid crystal cell 100-2 can be aligned. Thereafter, when the first liquid crystal cell 100-1 and the second liquid crystal cell 100-2 are pressed together so that they are adjacent to each other, the first liquid crystal cell 100-1 and the second liquid crystal cell 100-2 are bonded to each other via the adhesive layer 160.

[0128] In the above-described bonding method, alignment is performed based on the outer shape of the optical element 12, so there is no need to provide markers on the first substrate 111 and the second substrate 112. The above-described bonding method can be applied even when the planar shape of the optical element 12 is a polygon other than an octagon. The above-described bonding method can also be applied even when the planar shape of the optical element 12 is circular or elliptical. When the planar shape of the optical element 12 is circular or elliptical, the alignment jig 500 has a wall surface that coincides with the arc of the end face of the optical element 12 that follows the circular or elliptical shape.

[0129] 2. Method of bonding the first liquid crystal cell 100-1 and the second liquid crystal cell 100-2 in the optical element 12A] Fig. 22 is a schematic top view showing the configuration of the liquid crystal cell 100 of the optical element 12A according to one embodiment of the present invention. Fig. 23 is a schematic exploded plan view showing the connection configuration of the transparent electrodes 120 of the liquid crystal cell 100 of the optical element 12A according to one embodiment of the present invention. Fig. 24 is a schematic side view illustrating a method of bonding the first liquid crystal cell 100-1 and the second liquid crystal cell 100-2 in the optical element 12A according to one embodiment of the present invention.

[0130] In the optical element 12A, a light diffusion layer 112a is provided only on the second substrate 112 of the liquid crystal cell 100 (see FIG. 12). In the optical element 12A according to this embodiment, as shown in FIG. 22, the size of the second substrate 112 on which the light diffusion layer 112a is provided is smaller than the size of the first substrate 111. In a top view, the first substrate 111 includes two peripheral regions exposed from the second substrate 112. In the optical element 12A, a first terminal T1 to an eighth terminal T8 are provided on the first substrate 111. One of the two peripheral regions is provided with a first terminal T1 to a fourth terminal T4 and a first marker M1. The other of the two peripheral regions is provided with a fifth terminal T5 to an eighth terminal T8 and a second marker M2.

[0131] As described above, in the optical element 12A according to this embodiment, the first terminal T1 to the eighth terminal T8 are provided on the first substrate 111, and therefore, as shown in FIG. 23 , the second connection electrode C2, the third connection electrode C3, the sixth connection electrode C6, and the seventh connection electrode C7 are not required to electrically connect the first transparent electrode 121 and the second transparent electrode 122 to the wiring on the second substrate 112. The fifth terminal T5 is electrically connected to the first terminal T1 via the first wiring W1. The sixth terminal T6 is electrically connected to the second terminal T2 via the second wiring W2. The seventh terminal T7 is electrically connected to the third terminal T3 via the third wiring W3. The eighth terminal T8 is electrically connected to the fourth terminal T4 via the fourth wiring W4.

[0132] 24, the second liquid crystal cell 100-2 is rotated 180 degrees relative to the first liquid crystal cell 100-1, and is disposed on the first liquid crystal cell 100-1 so that the first marker M1 and the second marker M2 of the second liquid crystal cell 100-2 overlap with the second marker M2 and the first marker M1 of the first liquid crystal cell 100-1, respectively. The two peripheral regions where the first marker M1 and the second marker M2 are provided do not overlap with the light diffusion layers 112a of the first liquid crystal cell 100-1 and the second liquid crystal cell 100-2. Therefore, the first liquid crystal cell 100-1 and the second liquid crystal cell 100-2 can be aligned using the first marker M1 and the second marker M2. Thereafter, when the first liquid crystal cell 100-1 and the second liquid crystal cell 100-2 are pressed together so that they are close to each other, the first liquid crystal cell 100-1 and the second liquid crystal cell 100-2 are bonded together via the adhesive layer 160.

[0133] 3. Method for bonding the first liquid crystal cell 100-1 and the second liquid crystal cell 100-2 in the optical element 12B] FIG. 25 is a schematic side view illustrating a method for bonding the first liquid crystal cell 100-1 and the second liquid crystal cell 100-2 in the optical element 12B according to one embodiment of the present invention.

[0134] In the optical element 12B, a light diffusion layer 111a is provided only on the first substrate 111 of the liquid crystal cell 100 (see FIG. 13 ). The first substrate 111 and the second substrate 112 of the liquid crystal cell 100 include peripheral regions exposed from the second substrate 112 and the first substrate 111, respectively. As shown in FIG. 25 , a first marker M1 is provided in the peripheral region of the first substrate 111 exposed from the second substrate 112. Furthermore, a second marker M2 is provided in the peripheral region of the second substrate 112 exposed from the first substrate 111.

[0135] In FIG. 25, the second liquid crystal cell 100-2 is inverted and rotated 180 degrees relative to the first liquid crystal cell 100-1. The first marker M1 and the second marker M2 of the second liquid crystal cell 100-2 are disposed on the first liquid crystal cell 100-1 so as to overlap the second marker M2 and the first marker M1 of the first liquid crystal cell 100-1, respectively. The first marker M1 and the second marker M2 overlap the light diffusion layer 111a. However, the light diffusion layer 111a is not disposed between the first marker M1 and the second marker M2. Therefore, the first marker M1 and the second marker M2 can be read from the side of the peripheral region where the light diffusion layer 111a is not provided. Therefore, the first liquid crystal cell 100-1 and the second liquid crystal cell 100-2 can be aligned using the first marker M1 and the second marker M2. Thereafter, when the first liquid crystal cell 100-1 and the second liquid crystal cell 100-2 are pressed together so that they are close to each other, the first liquid crystal cell 100-1 and the second liquid crystal cell 100-2 are bonded together via the adhesive layer 160.

[0136] In this embodiment, the bonding process of the optical elements 12, 12A, and 12B described in the second embodiment has been described, but the above-described bonding method can also be applied to the bonding process of optical elements other than the optical elements 12, 12A, and 12B.

[0137] Within the scope of the concept of the present invention, a person skilled in the art may conceive of various modifications and alterations, and it is understood that these modifications and alterations also fall within the scope of the present invention. For example, to the above-described embodiments, a person skilled in the art may appropriately add or delete components or modify the design, or add or omit steps or change conditions, and these modifications and alterations are also included within the scope of the present invention as long as they maintain the gist of the present invention.

[0138] Furthermore, other effects and advantages brought about by each embodiment that are clear from the description in this specification or that can be appropriately conceived by a person skilled in the art are naturally understood to be brought about by the present invention.

[0139] 1, 1A, 1B, 1C, 2, 2A, 2B, 3, 3A, 3B, 3C: lighting device, 11, 11A, 11B, 11C, 12, 12A, 12B, 13, 13A, 13B, 13C: optical element, 20: light source, 100: liquid crystal cell, 100-1: first liquid crystal cell, 100-2: second liquid crystal cell, 100-3: third liquid crystal cell, 100-4: fourth liquid crystal cell, 111: first substrate, 111a: light diffusion layer, 112: second substrate, 112a: light diffusion layer, 120: transparent electrode, 121: first transparent electrode, 122: second transparent electrode, 123: third transparent electrode, 124: fourth transparent electrode, 131: First alignment film, 132: Second alignment film, 150: Liquid crystal layer, 160: Adhesive layer, 160a: Light diffusion layer, 170: Base material, 170a: Light diffusion layer, 500: Alignment jig, 501: First wall surface, 502: Second wall surface, 1000-1: First polarized component, 1000-2: Second polarized component, FPC, FPC1, FPC2: Flexible printed circuit board, C1: First connection electrode, C2: Second connection electrode, C3: Third connection electrode, C4: Fourth connection electrode, C5: Fifth connection electrode, C6: Sixth connection electrode, C7: Seventh connection electrode, C8: Eighth connection electrode, T1: First terminal, T2: Second terminal, T3: Third terminal, T4: fourth terminal, T5: fifth terminal, T6: sixth terminal, T7: seventh terminal, T8: eighth terminal, W1: first wiring, W2: second wiring, W3: third wiring, W4: fourth wiring, W5: fifth wiring, W6: sixth wiring, W7: seventh wiring, W8: eighth wiring

Claims

1. An optical element comprising: a plurality of liquid crystal cells including a first liquid crystal cell and a second liquid crystal cell stacked on the first liquid crystal cell; and at least one light diffusing layer overlapping the plurality of liquid crystal cells, wherein each of the first liquid crystal cell and the second liquid crystal cell comprises: a first substrate on which first transparent electrodes and second transparent electrodes extending in a first direction are alternately and repeatedly arranged in a second direction different from the first direction; a second substrate on which third transparent electrodes and fourth transparent electrodes extending in a third direction are alternately and repeatedly arranged in a fourth direction different from the third direction; and a first liquid crystal layer between the first substrate and the second substrate, wherein the total haze, calculated by adding up the hazes of one or more light diffusing layers provided outside the plurality of liquid crystal cells among the at least one light diffusing layer, is 50% or more.

2. The optical element according to claim 1, wherein the first liquid crystal cell and the second liquid crystal cell are stacked such that the second substrate of the first liquid crystal cell faces the first substrate of the second liquid crystal cell, and the at least one light diffusing layer includes a first light diffusing layer, and the first light diffusing layer is provided on one side of the first substrate of the first liquid crystal cell and the second substrate of the second liquid crystal cell.

3. The optical element of claim 2, wherein the first light diffusing layer is provided on a first surface of the base material, and a second surface of the base material opposite the first surface is bonded via an adhesive layer to one surface of the first substrate of the first liquid crystal cell and one surface of the second substrate of the second liquid crystal cell.

4. The optical element according to claim 2, wherein the first light diffusing layer contains a filler and an adhesive, and the first light diffusing layer is provided in contact with one surface of the first substrate of the first liquid crystal cell and one surface of the second substrate of the second liquid crystal cell.

5. The optical element according to claim 2, wherein the at least one light diffusing layer further includes a second light diffusing layer, the second light diffusing layer being provided on the other side of the first substrate of the first liquid crystal cell and the second substrate of the second liquid crystal cell.

6. The optical element of claim 1, wherein the first liquid crystal cell and the second liquid crystal cell are stacked such that the second substrate of the first liquid crystal cell faces the first substrate of the second liquid crystal cell, the at least one light diffusing layer includes a first light diffusing layer and a second light diffusing layer, the first light diffusing layer is provided on the surface of the second substrate of the first liquid crystal cell, and the second light diffusing layer is provided on the surface of the second substrate of the second liquid crystal cell.

7. The optical element according to claim 6, wherein the at least one light diffusing layer further includes a third light diffusing layer and a fourth light diffusing layer, the third light diffusing layer being provided on the surface of the first substrate of the first liquid crystal cell, and the fourth light diffusing layer being provided on the surface of the first substrate of the second liquid crystal cell.

8. The optical element described in claim 1, wherein the first liquid crystal cell and the second liquid crystal cell are stacked so that the second substrate of the first liquid crystal cell faces the second substrate of the second liquid crystal cell, the at least one light diffusing layer includes a first light diffusing layer and a second light diffusing layer, the first light diffusing layer is provided on the surface of the first substrate of the first liquid crystal cell, and the second light diffusing layer is provided on the surface of the first substrate of the second liquid crystal cell.

9. The optical element according to claim 8, wherein the first direction has a first angle with respect to a direction perpendicular to the second direction, and the third direction has a second angle with respect to a direction perpendicular to the fourth direction.

10. The optical element of claim 1, wherein the plurality of liquid crystal cells further include a third liquid crystal cell stacked on the second liquid crystal cell and a fourth liquid crystal cell stacked on the third liquid crystal cell, and each of the third liquid crystal cell and the fourth liquid crystal cell includes: a third substrate on which fifth transparent electrodes and sixth transparent electrodes extending in the second direction are alternately and repeatedly arranged in the first direction; a fourth substrate on which seventh transparent electrodes and eighth transparent electrodes extending in the first direction are alternately and repeatedly arranged in the second direction; and a second liquid crystal layer between the third substrate and the fourth substrate.

11. A liquid crystal display device comprising a plurality of liquid crystal cells including a first liquid crystal cell and a second liquid crystal cell stacked on the first liquid crystal cell; and at least one light diffusion layer overlapping the plurality of liquid crystal cells, wherein each of the first liquid crystal cell and the second liquid crystal cell comprises: a first substrate on which first transparent electrodes and second transparent electrodes extending in a first direction are alternately and repeatedly arranged in a second direction different from the first direction; a second substrate on which third transparent electrodes and fourth transparent electrodes extending in a third direction are alternately and repeatedly arranged in a fourth direction different from the third direction; and a first liquid crystal layer between the first substrate and the second substrate, wherein the at least one light diffusion layer comprises a first light diffusion layer, and the first light diffusion layer comprises a first filler and a first adhesive, and the first liquid crystal cell and the second liquid crystal cell are bonded via the first light diffusion layer, An optical element, wherein the total haze of the at least one light diffusing layer is 50% or more.

12. The optical element described in claim 11, wherein the at least one light diffusing layer further includes a second light diffusing layer provided outside the plurality of liquid crystal cells, the second light diffusing layer including a second filler and a second adhesive, and the second light diffusing layer is provided in contact with one surface of the first substrate of the first liquid crystal cell and one surface of the second substrate of the second liquid crystal cell.

13. The optical element described in claim 11, wherein the at least one light diffusing layer further includes a second light diffusing layer provided outside the plurality of liquid crystal cells, the second light diffusing layer being provided on a first surface of a substrate, and a second surface of the substrate opposite to the first surface being bonded via an adhesive to one surface of the first substrate of the first liquid crystal cell and the second substrate of the second liquid crystal cell.

14. The optical element described in claim 11, wherein the first liquid crystal cell and the second liquid crystal cell are stacked so that the second substrate of the first liquid crystal cell faces the second substrate of the second liquid crystal cell, the at least one light diffusing layer further includes a second light diffusing layer and a third light diffusing layer, the second light diffusing layer is provided on the surface of the first substrate of the first liquid crystal cell, and the third light diffusing layer is provided on the surface of the first substrate of the second liquid crystal cell.

15. The optical element of claim 11, wherein the first direction has a first angle with respect to a direction perpendicular to the second direction, and the third direction has a second angle with respect to a direction perpendicular to the fourth direction.

16. The plurality of liquid crystal cells further include a third liquid crystal cell stacked on the second liquid crystal cell and a fourth liquid crystal cell stacked on the third liquid crystal cell, each of the third liquid crystal cell and the fourth liquid crystal cell including: a third substrate on which fifth transparent electrodes and sixth transparent electrodes extending in the second direction are alternately and repeatedly arranged in the first direction; a fourth substrate on which seventh transparent electrodes and eighth transparent electrodes extending in the first direction are alternately and repeatedly arranged in the second direction; and a second liquid crystal layer between the third substrate and the fourth substrate; the at least one light diffusion layer further includes a second light diffusion layer and a third light diffusion layer; the second light diffusion layer includes a second filler and a second adhesive; the third light diffusion layer includes a third filler and a third adhesive; the second liquid crystal cell and the third liquid crystal cell are bonded via the second light diffusion layer; The optical element according to claim 11 , wherein the third liquid crystal cell and the fourth liquid crystal cell are bonded together via the third light diffusing layer.

17. An illumination device comprising the optical element according to any one of claims 1 to 16 and a light source disposed on the side of the first liquid crystal cell.

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