Optical element and luminaire

Abstract

To provide an optical element capable of controlling distribution of light or light distribution pattern.SOLUTION: An optical element includes two laminated liquid crystal cells. Each of the two liquid crystal cells includes: a first substrate on which a first transparent electrode and a second transparent electrode are arranged alternately in a first direction; a second substrate on which a third transparent electrode and a fourth transparent electrode are arranged alternately in a second direction intersecting the first direction; and a liquid crystal between the first substrate and the second substrate. The second substrate of one liquid crystal cell of the two liquid crystal cell is adjacent to the first substrate of the other liquid crystal cell of the two liquid crystal cells.SELECTED DRAWING: Figure 2A

Description

[Technical field]

[0001] An embodiment of the present invention relates to an optical element capable of controlling light distribution, and an illumination device including an optical element capable of controlling light distribution. [Background technology]

[0002] Conventionally, optical elements that utilize the change in refractive index of liquid crystals by adjusting the voltage applied to the liquid crystal, so-called liquid crystal lenses, have been known. In addition, development of lighting devices using light sources and liquid crystal lenses is underway (for example, see Patent Document 1, Patent Document 2, or Patent Document 3). [Prior art documents] [Patent documents]

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

[0004] However, the lighting device described in Patent Document 1 or Patent Document 2 merely aims to use a liquid crystal lens to control the spreading distribution of light, i.e., the light distribution angle of light, and to collect light. In other words, the lighting device described in Patent Document 1 or Patent Document 2 has a limited light distribution pattern that is concentric. In addition, the beam shaping device described in Patent Document 3 requires a liquid crystal cell with a complex configuration to obtain a variation in the light orientation pattern, such as changing the light distribution pattern by changing the pattern of electrodes applied to the liquid crystal, and thus has poor mass productivity.

[0005] In view of the above problems, an object of one embodiment of the present invention is to provide an optical element capable of controlling the light distribution or light distribution pattern of light, and an object of one embodiment of the present invention is to provide an illumination device capable of controlling the light distribution or light distribution pattern of light. [Means for solving the problem]

[0006] An optical element according to one embodiment of the present invention is an optical element including two stacked liquid crystal cells, each of which includes a first substrate having first transparent electrodes and second transparent electrodes alternately arranged in a first direction, a second substrate having third transparent electrodes and fourth transparent electrodes alternately arranged in a second direction intersecting the first direction, and liquid crystal between the first substrate and the second substrate, and the second substrate of one of the two liquid crystal cells is adjacent to the first substrate of the other of the two liquid crystal cells.

[0007] Moreover, an illumination device according to one embodiment of the present invention includes a light source and the optical element. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic perspective view of an optical element according to one embodiment of the present invention. [Figure 2A] 1 is a schematic cross-sectional view of an optical element according to one embodiment of the present invention. [Figure 2B] 1 is a schematic cross-sectional view of an optical element according to one embodiment of the present invention. [Figure 3A] FIG. 2 is a schematic plan view showing the arrangement of a first transparent electrode and a second transparent electrode on a first substrate in an optical element according to one embodiment of the present invention. [Figure 3B] FIG. 2 is a schematic plan view showing the arrangement of a third transparent electrode and a fourth transparent electrode on a second substrate in an optical element according to one embodiment of the present invention. [Figure 4A] 2 is a schematic cross-sectional view showing the orientation of liquid crystals in a liquid crystal layer in an optical element according to one embodiment of the present invention. FIG. [Figure 4B]2 is a schematic cross-sectional view showing the orientation of liquid crystals in a liquid crystal layer in an optical element according to one embodiment of the present invention. FIG. [Figure 5A] FIG. 2 is a schematic perspective view showing the orientation of liquid crystal molecules in a liquid crystal layer when a voltage is applied in an optical element according to one embodiment of the present invention. [Figure 5B] 3 is a schematic cross-sectional view showing the orientation of liquid crystal molecules in a liquid crystal layer when a voltage is applied in an optical element according to one embodiment of the present invention. FIG. [Figure 5C] 3 is a schematic cross-sectional view showing the orientation of liquid crystal molecules in a liquid crystal layer when a voltage is applied in an optical element according to one embodiment of the present invention. FIG. [Figure 6A] 1A to 1C are schematic cross-sectional views illustrating control of light distribution by an optical element according to an embodiment of the present invention. [Figure 6B] 1A to 1C are schematic cross-sectional views illustrating control of light distribution by an optical element according to an embodiment of the present invention. [Figure 7A] 4 is a timing chart showing voltages applied to each transparent electrode included in an optical element according to one embodiment of the present invention. [Figure 7B] 7B is a photograph of a light distribution pattern obtained by applying the potentials shown in FIG. 7A to each transparent electrode in an optical element according to one embodiment of the present invention. [Figure 8A] 4 is a timing chart showing voltages applied to each transparent electrode included in an optical element according to one embodiment of the present invention. [Figure 8B] 8B is a photograph of a light distribution pattern obtained by applying the potentials shown in FIG. 8A to each transparent electrode in an optical element according to one embodiment of the present invention. [Figure 9A] 4 is a timing chart showing voltages applied to each transparent electrode included in an optical element according to one embodiment of the present invention. [Figure 9B] 9B is a photograph of a light distribution pattern obtained by applying the potentials shown in FIG. 9A to each transparent electrode in an optical element according to one embodiment of the present invention. [Figure 10] 4 is a timing chart showing voltages applied to each transparent electrode included in an optical element according to one embodiment of the present invention. [Figure 11] 1 is a graph showing relative front luminance versus d / p in a liquid crystal cell of an optical element according to one embodiment of the present invention. [Figure 12] 1 is a schematic diagram showing a configuration of an illumination device according to an embodiment of the present invention; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

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

[0010] In order to clarify the description, the drawings may show the width, thickness, shape, etc. of each part in a schematic manner compared to the actual embodiment, but these are merely examples, and the illustrated shapes themselves do not limit the interpretation of the present invention. In addition, in the drawings, elements having the same functions as those explained in the drawings already shown in the specification may be given the same reference numerals even in different drawings, and duplicate explanations may be omitted.

[0011] When a film is processed to form multiple structures, each structure may have a different function or role, and each structure may be formed on a different base. However, these multiple structures are derived from a film formed as the same layer in the same process, and have the same material. Therefore, these multiple films are defined as existing in the same layer.

[0012] When expressing an aspect in which a structure is placed on top of another structure, the term "above" is used, unless otherwise specified, to include both a case in which another structure is placed directly above, in contact with, a structure, and a case in which another structure is placed above, via yet another structure.

[0013] First Embodiment An optical element 10 according to one embodiment of the present invention will be described with reference to FIGS.

[0014] [1. Configuration of optical elements] Fig. 1 is a schematic perspective view of an optical element 10 according to one embodiment of the present invention. As shown in Fig. 1, the optical element 10 includes a first liquid crystal cell 110, a second liquid crystal cell 120, and an optical elastic resin layer 130. The optical elastic resin layer 130 is provided between the first liquid crystal cell 110 and the second liquid crystal cell 120. That is, the first liquid crystal cell 110 and the second liquid crystal cell 120 are laminated in the z-axis direction with the optical elastic resin layer 130 sandwiched therebetween.

[0015] The optical elastic resin layer 130 can bond and fix the first liquid crystal cell 110 and the second liquid crystal cell 120. As the optical elastic resin layer 130, an adhesive material containing an optical elastic resin, for example, an acrylic resin having light transmission properties, can be used.

[0016] Figures 2A and 2B are schematic cross-sectional views of an optical element 10 according to one embodiment of the present invention. Specifically, Figure 2A is a schematic cross-sectional view in a zx plane cut along line A1-A2 shown in Figure 1, and Figure 2B is a schematic cross-sectional view in a yz plane cut along line B1-B2 shown in Figure 1. In the following, the x-axis direction and the y-axis direction may be referred to as a first direction and a second direction, respectively.

[0017] The first liquid crystal cell 110 includes a first substrate 111-1, a second substrate 111-2, a first transparent electrode 112-1, a second transparent electrode 112-2, a third transparent electrode 112-3, a fourth transparent electrode 112-4, a liquid crystal layer 113, a first alignment film 114-1, a second alignment film 114-2, and a sealant 115. The second liquid crystal cell 120 includes a first substrate 121-1, a second substrate 121-2, a first transparent electrode 122-1, a second transparent electrode 122-2, a third transparent electrode 122-3, a fourth transparent electrode 122-4, a liquid crystal layer 123, a first alignment film 124-1, a second alignment film 124-2, and a sealant 125.

[0018] The optical element 10 has two liquid crystal cells, and it is preferable that the two liquid crystal cells have the same configuration. Therefore, in the following, only the configuration of the first liquid crystal cell 110 will be described, and for convenience, the description of the configuration of the second liquid crystal cell 120 may be omitted.

[0019] A first transparent electrode 112-1 and a second transparent electrode 112-2 are provided on the first substrate 111-1. Also, a first alignment film 114-1 is provided to cover the surfaces of the first transparent electrode 112-1, the second transparent electrode 112-2, and the first substrate 111-1.

[0020] A third transparent electrode 112-3 and a fourth transparent electrode 112-4 are provided on the second substrate 111-2. In addition, a second alignment film 114-2 is provided to cover the surfaces of the third transparent electrode 112-3, the fourth transparent electrode 112-4, and the second substrate 111-2.

[0021] The first substrate 111-1 and the second substrate 111-2 are arranged so that the first transparent electrode 112-1 and the second transparent electrode 112-2 on the first substrate 111-1 face each other, and the third transparent electrode 112-3 and the fourth transparent electrode 112-4 on the second substrate 111-2 face each other.

[0022] Also, a sealant 115 is disposed on the periphery of each of the first substrate 111-1 and the second substrate 111-2. That is, the first substrate 111-1 and the second substrate 111-2 are bonded via the sealant 115. Also, liquid crystal is sealed in a space surrounded by the first substrate 111-1 (more specifically, the first alignment film 114-1), the second substrate 111-2 (more specifically, the second alignment film 114-2), and the sealant 115, and a liquid crystal layer 113 is formed.

[0023] Each of the first substrate 111-1 and the second substrate 111-2 may be a rigid substrate having light transmission properties, such as a glass substrate, a quartz substrate, a sapphire substrate, etc. Also, each of the first substrate 111-1 and the second substrate 111-2 may be a flexible substrate having light transmission properties, such as a polyimide resin substrate, an acrylic resin substrate, a siloxane resin substrate, or a fluororesin substrate.

[0024] Each of the first transparent electrode 112-1, the second transparent electrode 112-2, the third transparent electrode 112-3, and the fourth transparent electrode 112-4 functions as an electrode for forming an electric field in the liquid crystal layer 113. Each of the first transparent electrode 112-1, the second transparent electrode 112-2, the third transparent electrode 112-3, and the fourth transparent electrode 112-4 is made of a transparent conductive material such as indium tin oxide (ITO) or indium zinc oxide (IZO).

[0025] The liquid crystal layer 113 can refract the light passing therethrough or change the polarization state of the light passing therethrough depending on the orientation state of the liquid crystal molecules. For example, nematic liquid crystal can be used as the liquid crystal of the liquid crystal layer 113. In this embodiment, the liquid crystal is of the positive type, but it is also possible to adopt a negative type by changing the initial orientation direction of the liquid crystal molecules. In addition, the liquid crystal preferably contains a chiral agent that imparts a twist to the liquid crystal molecules.

[0026] Each of the first alignment film 114-1 and the second alignment film 114-2 aligns the liquid crystal molecules in the liquid crystal layer 113 in a predetermined direction. Each of the first alignment film 114-1 and the second alignment film 114-2 can be made of, for example, a polyimide resin. Each of the first alignment film 114-1 and the second alignment film 114-2 may be given an alignment characteristic by an alignment treatment such as a rubbing method or a photo-alignment method. The rubbing method is a method of rubbing the surface of the alignment film in one direction. The photo-alignment method is a method of irradiating the alignment film with linearly polarized ultraviolet light.

[0027] The sealant 115 bonds and fixes the first substrate 111-1 and the second substrate 111-2. For example, an epoxy resin adhesive or an acrylic resin adhesive can be used as the sealant 115. The adhesive may be an ultraviolet curing type or a thermosetting type.

[0028] Although the details will be described later, the optical element 10 includes two liquid crystal cells (first liquid crystal cell 110 and second liquid crystal cell 120) and is therefore capable of controlling the distribution of unpolarized light and forming a light distribution pattern. Therefore, there is no need to provide a pair of polarizing plates, such as those provided on the front and back surfaces of a liquid crystal display element, on the outer surfaces of each substrate.

[0029] [2. Placement of transparent electrodes] The arrangement of each of the first transparent electrode 112-1, the second transparent electrode 112-2, the third transparent electrode 112-3, and the fourth transparent electrode 112-4 will be described in detail with reference to FIGS. 3A and 3B.

[0030] Fig. 3A is a schematic plan view showing the arrangement of the first transparent electrode 112-1 and the second transparent electrode 112-2 on the first substrate 111-1 in the optical element 10 according to one embodiment of the present invention. Fig. 3B is a schematic plan view showing the arrangement of the third transparent electrode 112-3 and the fourth transparent electrode 112-4 on the second substrate 111-2 in the optical element 10 according to one embodiment of the present invention. Note that Figs. 3A and 3B each show the arrangement of the transparent electrodes as viewed from the first liquid crystal layer 115-1 side.

[0031] As shown in FIG. 3A, each of the first transparent electrode 112-1 and the second transparent electrode 112-2 has a first width a1 in the x-axis direction and extends in the y-axis direction. The first transparent electrode 112-1 and the second transparent electrode 112-2 have a first inter-electrode distance b1 in the x-axis direction and are alternately arranged. That is, the first transparent electrode 112-1 and the second transparent electrode 112-2 have a first pitch p1, and p1=a1+b1 is satisfied. The first transparent electrode 112-1 and the second transparent electrode 112-2 are electrically connected to the first wiring 116-1 and the second wiring 116-2 formed on the first substrate 111-1, respectively. The first wiring 116-1 may be formed under the first transparent electrode 112-1, or may be formed on the first transparent electrode 112-1. In this case, the first wiring 116-1 may be made of metal. The first wiring 116-1 may be formed in the same layer as the first transparent electrode 112-1. The same applies to the second wiring 116-2.

[0032] The first alignment film 114-1 is aligned in the x-axis direction. In this case, the long axes of the liquid crystal molecules on the first substrate 111-1 side among the liquid crystal molecules constituting the liquid crystal layer 113 are aligned along the x-axis direction in the absence of an electric field. That is, the alignment direction (x-axis direction) of the first alignment film 114-1 and the extension direction (y-axis direction) of the first transparent electrode 112-1 or the second transparent electrode 112-2 are orthogonal to each other. The alignment process may be an alignment process by rubbing or photo-alignment. The alignment directions of the first alignment film 114-1 and the second alignment film 114-2 may be perpendicular to each other as long as they are perpendicular to each other, and each alignment direction may intersect with the extension direction of the transparent electrode on which the first alignment film 114-1 or the second alignment film 114-2 is provided at an angle other than a right angle.

[0033] As shown in FIG. 3B, each of the third transparent electrode 112-3 and the fourth transparent electrode 112-4 has a second width a2 in the y-axis direction and extends in the x-axis direction. The third transparent electrode 112-3 and the fourth transparent electrode 112-4 have a second inter-electrode distance b2 in the y-axis direction and are alternately arranged. That is, the third transparent electrode 112-3 and the fourth transparent electrode 112-4 have a second pitch p2, and satisfy p2=a2+b2. The third transparent electrode 112-3 and the fourth transparent electrode 112-4 are electrically connected to the third wiring 116-3 and the fourth wiring 116-4 formed on the second substrate 111-2, respectively. The third wiring 116-3 and the fourth wiring 116-4 may be formed under the third transparent electrode 112-3 and the fourth transparent electrode 112-4, or may be formed on the third transparent electrode 112-3 and the fourth transparent electrode 112-4. In this case, the third wiring 116-3 and the fourth wiring 116-4 may be formed of a metal. In addition, the third wiring 116-3 and the fourth wiring 116-4 may be formed in the same layer as the third transparent electrode 112-3 and the fourth transparent electrode 112-4.

[0034] The second alignment film 114-2 is subjected to an alignment treatment in the y-axis direction. In this case, the long axes of the liquid crystal molecules on the second substrate 111-2 side among those constituting the liquid crystal layer 113 are aligned along the y-axis direction in the absence of an electric field. That is, the alignment direction (y-axis direction) of the second alignment film 114-2 is perpendicular to the extension direction (x-axis direction) of the third transparent electrode 112-3 or the fourth transparent electrode 112-4.

[0035] It can also be said that the first transparent electrode 112-1 and the second transparent electrode 112-2 are formed on the first substrate 111-1 in a comb-like pattern having a first pitch p1. Similarly, it can also be said that the third transparent electrode 112-3 and the fourth transparent electrode 112-4 are formed on the second substrate 111-2 in a comb-like pattern having a second pitch p2.

[0036] In the first liquid crystal cell 110, the first transparent electrode 112-1 and the second transparent electrode 112-2 face the third transparent electrode 112-3 and the fourth transparent electrode 112-4 via the liquid crystal layer 113. Here, the direction in which the first transparent electrode 112-1 and the second transparent electrode 112-2 extend (y-axis direction) is perpendicular to the direction in which the third transparent electrode 112-3 and the fourth transparent electrode extend (x-axis direction). In other words, the comb-shaped electrode pattern formed on the first substrate 111-1 and the comb-shaped electrode pattern formed on the second substrate are perpendicular to each other in a plan view. In addition, a fifth wiring 116-5 and a sixth wiring 116-6 are formed on the first substrate 111-1. When the first substrate 111-1 and the second substrate 111-2 are attached to each other, the third wiring 116-3 and the fourth wiring 116-4 are electrically connected to the fifth wiring 116-5 and the sixth wiring 116-6 provided on the first substrate 111-1, respectively. The electrical connection between the third wiring 116-3 and the fifth wiring 116-5 and the electrical connection between the fourth wiring 116-4 and the sixth wiring 116-6 can be made using, for example, silver paste or conductive particles (including particles coated with metal).

[0037] In this embodiment, the first direction in which the first transparent electrodes 112-1 and the second transparent electrodes 112-2 are alternately arranged and the second direction in which the third transparent electrodes 112-3 and the fourth transparent electrodes 112-4 are alternately arranged are orthogonal to each other, but as long as they intersect, the intersection angle may be other than 90 degrees. In addition, the first transparent electrodes 112-1 and the second transparent electrodes 112-2 of the first substrate 111-1 intersect with the third transparent electrodes 112-3 and the fourth transparent electrodes 112-4 of the second substrate, so that the orientation of the liquid crystal in the liquid crystal layer 113 can be controlled by controlling the voltage applied to each transparent electrode, as described later. This allows the orientation or light distribution pattern of light to be controlled.

[0038] On the first substrate 111-1 or the second substrate 111-2, a photospacer (not shown) is formed to maintain the distance therebetween.

[0039] Each of the first wiring 116-1, the second wiring 116-2, the third wiring 116-3, the fourth wiring 116-4, the fifth wiring 116-5, and the sixth wiring 116-6 can be made of, for example, a metal material such as aluminum or molybdenum, or a transparent conductive material such as indium tin oxide (ITO) or indium zinc oxide (IZO). Each of the first wiring 116-1, the second wiring 116-2, the fifth wiring 116-5, and the sixth wiring 116-6 may be provided with a terminal for connecting to an external device.

[0040] The first wiring 116-1, the second wiring 116-2, the fifth wiring 116-5 (or the third wiring 116-3), and the sixth wiring 116-6 (or the fourth wiring 116-4) are electrically insulated from each other. Therefore, in the first liquid crystal cell 110, the orientation of the liquid crystal molecules in the liquid crystal layer 113 can be controlled by applying different voltages to the first transparent electrode 112-1, the second transparent electrode 112-2, the third transparent electrode 112-3, and the fourth transparent electrode 112-4, respectively.

[0041] [3. Control of liquid crystal alignment] The alignment of the liquid crystal in the liquid crystal layer 113 will be described in detail with reference to FIG. 4A and FIG. 4B.

[0042] 4A and 4B are schematic cross-sectional views showing the orientation of liquid crystal molecules in a liquid crystal layer 113 in an optical element 10 according to one embodiment of the present invention. Figures 4A and 4B correspond to parts of the cross-sectional views of the first liquid crystal cell 110 shown in Figures 2A and 2B, respectively.

[0043] As shown in FIG. 4A and FIG. 4B, the first substrate 111-1 and the second substrate 111-2 are bonded together to have a substrate distance d. The first alignment film 114-1 of the first substrate 111-1 and the second alignment film 114-2 of the second substrate 111-2 are aligned in the x-axis direction and the y-axis direction, respectively. Therefore, in the liquid crystal layer 113, the liquid crystal molecules on the first substrate 111-1 side are aligned with their major axes along the x-axis direction when no voltage is applied to the transparent electrodes (for convenience, in FIG. 4A and FIG. 4B, the alignment direction of the liquid crystal molecules aligned in the left-right direction of the paper is indicated by an arrow). That is, the alignment direction of the liquid crystal molecules on the first substrate 111-1 side is perpendicular to the extension direction of the first transparent electrode 112-1 and the second transparent electrode 112-2. In addition, the liquid crystal molecules on the second substrate 111-2 side are aligned with their major axes along the y-axis direction when no voltage is applied to the transparent electrodes (for convenience, in FIG. 4A and FIG. 4B, the alignment direction of the liquid crystal molecules aligned in the normal direction to the paper surface is indicated by a symbol of a circle with a cross inside). That is, the alignment direction of the liquid crystal molecules on the second substrate 111-2 side is perpendicular to the extending direction of the third transparent electrode 112-3 and the fourth transparent electrode 112-4. Therefore, the liquid crystal molecules of the liquid crystal layer 113 are aligned in the z-axis direction in a state where they are twisted by 90 degrees from the first substrate 111-1 to the second substrate 111-2. More specifically, in FIG. 4A, the liquid crystal molecules on the first substrate 111-1 side are aligned with their major axes facing the x-axis direction (left-right direction on the paper surface) along the alignment direction of the first alignment film 114-1. The liquid crystal molecules on the second substrate 111-2 side are aligned with their major axes pointing in the y-axis direction (normal to the page) along the alignment direction of the second alignment film 114-2. The liquid crystal molecules between them gradually change the orientation of their major axes from the x-axis direction to the y-axis direction as they move from the first substrate 111-1 to the second substrate 111-2.

[0044] Next, the alignment of the liquid crystal in the liquid crystal layer 113 when a voltage is applied will be described in detail with reference to FIGS. 5A to 5C.

[0045] FIG. 5A is a schematic perspective view showing the orientation of liquid crystal molecules in the liquid crystal layer 113 when a voltage is applied in the optical element 10 according to one embodiment of the present invention. Also, FIG. 5B and FIG. 5C are schematic cross-sectional views showing the orientation of liquid crystal molecules in the liquid crystal layer 113 when a voltage is applied in the optical element 10 according to one embodiment of the present invention. In FIG. 5A, the first alignment film 114-1 and the second alignment film 114-2 are omitted for convenience. Also, in FIG. 5B and FIG. 5C, the alignment directions of the first alignment film 114-1 and the second alignment film 114-2 are illustrated using an arrow or a symbol with a cross in a circle, as in FIG. 4A and FIG. 4B.

[0046] In Fig. 5A to Fig. 5C, a low potential is applied to the first transparent electrode 112-1 and the third transparent electrode 112-3, and a high potential is applied to the second transparent electrode 112-2 and the fourth transparent electrode 112-4 (for convenience, in Fig. 5A to Fig. 5C, the low potential and the high potential are illustrated using the symbols "-" and "+", respectively). That is, a potential difference is generated between the first transparent electrode 112-1 and the second transparent electrode 112-2 and between the third transparent electrode 112-3 and the fourth transparent electrode 112-4. In this case, the liquid crystal molecules on the first substrate 111-1 side are oriented according to the electric field (potential distribution) generated between the first transparent electrode 112-1 and the second transparent electrode 112-2. That is, the long axes of the liquid crystal molecules on the first substrate 111-1 are aligned along the direction from the first transparent electrode 112-1 to the second transparent electrode 112-2. Similarly, the liquid crystal molecules on the second substrate 111-2 are aligned along the direction from the third transparent electrode 112-3 to the fourth transparent electrode 112-4. In the following description, the electric field generated between adjacent transparent electrodes on the same substrate may be referred to as a lateral electric field.

[0047] The orientation of the liquid crystal molecules will now be described in detail. The liquid crystal molecules on the first substrate 111-1 side are aligned in the x-axis direction in the absence of an electric field, and the orientation of the liquid crystal molecules is the same as the direction of the transverse electric field between the first transparent electrode 112-1 and the second transparent electrode 112-2. Therefore, the orientation of the liquid crystal molecules located almost at the center between the first transparent electrode 112-1 and the second transparent electrode 112-2 in a plan view is hardly changed even by the transverse electric field. Moreover, the liquid crystal molecules closer to the first transparent electrode 112-1 or the second transparent electrode 112-2 than the center are aligned with a tilt in the z-axis direction in response to the transverse electric field. Therefore, as shown in FIG. 5B, due to the influence of the transverse electric field between the first transparent electrode 112-1 and the second transparent electrode 112-2, the liquid crystal molecules on the first substrate 111-1 side are oriented in a convex arc shape from the first transparent electrode 112-1 to the second transparent electrode 112-2 as viewed from the first substrate 111-1 for each adjacent transparent electrode. Similarly, the liquid crystal molecules on the second substrate 111-2 side are oriented in the y-axis direction, but the orientation of the liquid crystal molecules is the same as the direction of the transverse electric field between the third transparent electrode 112-3 and the fourth transparent electrode 112-4. Therefore, the orientation of the liquid crystal molecules located almost at the center between the third transparent electrode 112-3 and the fourth transparent electrode 112-4 is hardly changed even by the transverse electric field. In addition, the liquid crystal molecules closer to the third transparent electrode 112-3 or the fourth transparent electrode 112-4 than the center are oriented with a tilt in the z-axis direction. 5C, due to the influence of the transverse electric field between the third transparent electrode 112-3 and the fourth transparent electrode 112-4, the liquid crystal molecules on the second substrate 111-2 side are aligned in a convex arc shape from the third transparent electrode 112-3 to the fourth transparent electrode 112-4 as viewed from the second substrate 111-2 for each space between adjacent transparent electrodes. Therefore, light incident on the liquid crystal layer 113 is diffused in accordance with the refractive index distribution of the liquid crystal molecules aligned in a convex arc shape on the first substrate 111-1 side or the second substrate 111-2 side.

[0048] Since the first substrate 111-1 and the second substrate 111-2 are sufficiently separated by a substrate distance d, the horizontal electric field between the first transparent electrode 112-1 and the second transparent electrode 112-2 of the first substrate 111-1 does not affect the alignment of the liquid crystal molecules on the second substrate 111-2 side, or the effect is negligibly small. Similarly, the horizontal electric field between the third transparent electrode 112-3 and the fourth transparent electrode 112-4 of the second substrate 111-2 does not affect the alignment of the liquid crystal molecules on the first substrate 111-1 side, or the effect is negligibly small.

[0049] In this specification, the liquid crystal layer 113 (or liquid crystal molecules) on the first substrate 111-1 side refers to the liquid crystal layer (or liquid crystal molecules) from the surface of the first substrate 111-1 to d / 2. Similarly, the liquid crystal layer 113 (or liquid crystal molecules) on the second substrate 111-2 side refers to the liquid crystal layer (or liquid crystal molecules) from the surface of the second substrate 111-2 to d / 2.

[0050] In the first liquid crystal cell 110, the orientation of the liquid crystal molecules in the liquid crystal layer 113 can be changed by controlling the voltages applied to the first transparent electrode 112-1, the second transparent electrode 112-2, the third transparent electrode 112-3, and the fourth transparent electrode. The change in the orientation of the liquid crystal molecules changes the refractive index distribution of the liquid crystal layer 113. Therefore, the first liquid crystal cell 110 can diffuse the light passing through it. The optical element 10 can control the light distribution or light distribution pattern of the light passing through the optical element 10 by utilizing the change in the refractive index distribution of the liquid crystal layer 113 of the first liquid crystal cell 110 and the liquid crystal layer 123 of the second liquid crystal cell 120.

[0051] [5. Control of light distribution or orientation pattern using optical elements] The control of the light distribution or light distribution pattern by the optical element 10 will be described in detail with reference to FIGS. 6A and 6B.

[0052] 6A and 6B are schematic cross-sectional views for explaining the control of light distribution by the optical element 10 according to an embodiment of the present invention. The optical element 10 shown in FIG. 6A and FIG. 6B corresponds to a part of the cross-sectional view of the first liquid crystal cell 110 and the second liquid crystal cell 120 shown in FIG. 2A. In the optical element 10 shown in FIG. 6A, no potential is applied to any of the transparent electrodes. In addition, in the optical element 10 shown in FIG. 6B, a low potential is applied to the first transparent electrode 112-1 and the third transparent electrode 112-3 of the first liquid crystal cell 110, and a high potential is applied to the second transparent electrode 112-2 and the fourth transparent electrode 112-4. Similarly, a low potential is applied to the first transparent electrode 122-1 and the third transparent electrode 122-3 of the second liquid crystal cell 120, and a high potential is applied to the second transparent electrode 122-2 and the fourth transparent electrode 122-4. In FIG. 6B, for convenience, low potential and high potential are illustrated using the symbols "-" and "+", respectively.

[0053] In the optical element 10 shown in FIG. 6A and FIG. 6B, the first alignment film 114-1 of the first liquid crystal cell 110 and the first alignment film 124-1 of the second liquid crystal cell 120 are aligned in the x-axis direction. On the other hand, the second alignment film 114-2 of the first liquid crystal cell 110 and the second alignment film 124-2 of the second liquid crystal cell 120 are aligned in the y-axis direction. Therefore, in the first liquid crystal cell 110, the alignment direction of the first alignment film 114-1 is the x-axis direction, and the alignment direction of the second alignment film 114-2 is the y-axis direction. Similarly, in the second liquid crystal cell 120, the alignment direction of the first alignment film 124-1 is the x-axis direction, and the alignment direction of the second alignment film 124-2 is the y-axis direction.

[0054] In the optical element 10 in which the first liquid crystal cell 110 and the second liquid crystal cell 120 are laminated, the first transparent electrode 112-1 of the first liquid crystal cell 110 and the first transparent electrode 122-1 of the second liquid crystal cell 120 overlap each other so as to be substantially aligned in the extension direction in a plan view. The same applies to the other transparent electrodes. However, the first liquid crystal cell 110 and the second liquid crystal cell 120 may be arranged such that the first transparent electrode 112-1 of the first liquid crystal cell 110 and the first transparent electrode 122-1 of the second liquid crystal cell 120 overlap each other with a slight deviation in the x-axis direction or the y-axis direction. More specifically, in a plan view, the first transparent electrode 112-1 of the first liquid crystal cell 110 and the first transparent electrode 122-1 of the second liquid crystal cell 120 overlap each other partially or entirely in the extension direction. Alternatively, the first transparent electrode 112-1 of the first liquid crystal cell 110 and the first transparent electrode 122-1 of the second liquid crystal cell 120 need not overlap each other as long as they extend in the same direction.

[0055] In Figures 6A and 6B, light is incident on the first substrate 111-1 of the first liquid crystal cell 110 in a direction perpendicular to the first substrate 111-1, and is emitted from the second substrate 121-2 of the second liquid crystal cell 120. The light incident on the first substrate 111-1 of the first liquid crystal cell 110 has polarization in the x-axis direction (P-polarized component) and polarization in the y-axis direction (S-polarized component). For convenience, the following description will refer to the x-axis direction polarized component of the light emitted from the light source as the first polarized component 310 and the y-axis direction polarized component as the second polarized component 320, and will explain the process in which these polarized components pass through the optical element 10 of Figure 6B.

[0056] First polarized component 310 and second polarized component 320 correspond to the P polarized component and the S polarized component of the light emitted from the light source, respectively (see (1) in FIG. 6B). Note that in FIG. 6A and FIG. 6B, the P polarized component is illustrated using an arrow (arrow pointing in the horizontal direction on the page), and the S polarized component is illustrated using a symbol of a circle with a cross (arrow pointing in the normal direction on the page).

[0057] The liquid crystal molecules of the liquid crystal layer 113 on the first substrate 111-1 side of the first liquid crystal cell 110 have their major axes oriented along the x-axis direction, so that when a transverse electric field is generated between the first transparent electrode 112-1 and the second transparent electrode 112-2, the liquid crystal molecules have a refractive index distribution in the x-axis direction, as shown in Fig. 6B. Also, the liquid crystal molecules of the liquid crystal layer 113 on the second substrate 111-2 side of the first liquid crystal cell 110 have their major axes oriented along the y-axis direction, so that when a transverse electric field is generated between the third transparent electrode 112-3 and the fourth transparent electrode 112-4, the liquid crystal molecules have a refractive index distribution in the y-axis direction.

[0058] Therefore, the first polarized component 310 incident on the optical element 10 (more specifically, the first liquid crystal cell 110) is changed to an S-polarized component according to the twist of the liquid crystal orientation as it travels toward the second substrate 111-2 after being incident on the first substrate 111-1 (see (2) to (4) in FIG. 6B). More specifically, the first polarized component 310 has a polarization axis in the x-axis direction on the first substrate 111-1 side, but the polarization axis gradually changes while passing through the thickness direction of the liquid crystal layer 113, and has a polarization axis in the y-axis direction on the second substrate 111-2 side, and then is emitted from the second substrate 111-2 side (see (5) in FIG. 6B). Here, as shown in FIG. 6B, when a transverse electric field is generated between the first transparent electrode 112-1 and the second transparent electrode 112-2, the orientation state of the liquid crystal molecules changes as shown in FIG. 5A under the influence of the transverse electric field, and the refractive index distribution changes. Moreover, the first polarized component 310, on the first substrate 111-1 side, has a polarization axis parallel to the alignment direction of the liquid crystal molecules of the liquid crystal layer 113 on the first substrate 111-1 side, and therefore diffuses in the x-axis direction according to the change in the refractive index distribution of the liquid crystal molecules. Moreover, the polarization axis of the first polarized component 310 becomes parallel to the alignment direction of the liquid crystal molecules of the liquid crystal layer 113 on the second substrate 111-2 side by changing the polarization axis from the x-axis direction to the y-axis direction in the liquid crystal layer 113. Here, as shown in FIG. 6B, when a transverse electric field is generated between the third transparent electrode 112-3 and the fourth transparent electrode 112-4, the alignment state of the liquid crystal molecules changes as shown in FIG. 5B under the influence of the transverse electric field, and the refractive index distribution changes. Therefore, the first polarized component 310 diffuses in the y-axis direction according to the change in the refractive index distribution of the liquid crystal molecules.

[0059] 6B, the second polarized light component 320, which was an S-polarized light component before entering the optical element 10 (more specifically, the first liquid crystal cell 110), enters the first substrate 111-1 and then changes to a P-polarized light component due to the twist of the liquid crystal orientation as it travels toward the second substrate 111-2 (see (2) to (4) in FIG. 6B). More specifically, the second polarized light component 320 has a polarization axis in the y-axis direction on the first substrate 111-1 side, but gradually changes its polarization axis while passing through the thickness direction of the liquid crystal layer 113, and has a polarization axis in the x-axis direction on the second substrate 111-2 side, and is then emitted from the second substrate 111-2 side (see (5) in FIG. 6B). Here, even if a transverse electric field is generated between the first transparent electrode 112-1 and the second transparent electrode 112-2, the second polarized component 320 is not affected by the refractive index distribution of the liquid crystal molecules on the first substrate 111-1 side because the polarization axis of the second polarized component 320 is perpendicular to the alignment direction of the liquid crystal molecules of the liquid crystal layer 113 on the first substrate 111-1 side, and passes through as it is without being diffused. In addition, by changing the polarization axis of the second polarized component 320 from the y-axis direction to the x-axis direction in the liquid crystal layer 113, the polarization axis of the second polarized component 320 is also perpendicular to the alignment direction of the liquid crystal molecules on the second substrate 111-2 side, and passes through as it is without being affected by the refractive index distribution of the liquid crystal molecules.

[0060] In other words, the second polarized component 320, which was an S-polarized component before entering the optical element 10, changes its polarization axis from the y-axis direction to the x-axis direction as it passes through the first liquid crystal cell 110 and becomes a P-polarized component, but does not undergo diffusion like the first polarized component 310.

[0061] The liquid crystal molecules in the liquid crystal layer 123 of the second liquid crystal cell 120 have a refractive index distribution similar to that of the liquid crystal molecules in the liquid crystal layer 113 of the first liquid crystal cell 110. Therefore, in the second liquid crystal cell 120, the same phenomenon as that in the first liquid crystal cell 110 basically occurs. On the other hand, the polarization axes of the first polarized component 310 and the second polarized component 320 are switched by passing through the first liquid crystal cell 110, and therefore the polarized components affected by the refractive index distribution of the liquid crystal molecules in the liquid crystal layer 113 are also switched. That is, as shown in Fig. 6B, even if a transverse electric field is generated between the first transparent electrode 122-1 and the second transparent electrode 122-2 and between the third transparent electrode 122-3 and the fourth transparent electrode 112-4 of the second liquid crystal cell 120, the first polarized component 310 passing through the second liquid crystal cell 120 changes its polarization axis from the y-axis direction back to the x-axis direction (see (6) to (8) in Fig. 6B), but does not diffuse. On the other hand, the second polarized component 320 passing through the second liquid crystal cell 120 changes its polarization axis from the x-axis direction back to the y-axis direction (see (6) to (8) in Fig. 6B), and is diffused due to the influence of the refractive index distribution of the liquid crystal molecules in the liquid crystal layer 123.

[0062] As can be seen from the above, in the optical element 10, by stacking two liquid crystal cells having the same structure, the polarization direction of the light incident on the optical element 10 is changed twice, and as a result, the polarization direction before and after the incident can be made to remain the same (see (1) and (9) in FIG. 6B). On the other hand, the optical element 10 can change the refractive index distribution of the liquid crystal molecules in the liquid crystal layer of the liquid crystal cell, and refract the light that passes through. More specifically, the first liquid crystal cell 110 diffuses the light of the first polarized component 310 (P polarized component) in the x-axis direction, the y-axis direction, or both the x-axis and y-axis directions, and the second liquid crystal cell 120 diffuses the light of the second polarized component 320 (S polarized component) in the x-axis direction, the y-axis direction, or both the x-axis and y-axis directions. Therefore, the optical element 10 can diffuse unpolarized light without changing the polarization state of the light.

[0063] In the above, the process of diffusing and changing the polarization axis of each polarized component as it passes through optical element 10 has been described mainly with reference to FIG. 6B. Optical element 10 in FIG. 6A is in a state where no potential is applied to each transparent electrode (a state where there is no potential difference between adjacent transparent electrodes), and changes the polarization axis of the polarized component in the same way as the optical element in FIG. 6B, except that it does not diffuse the polarized components. To avoid duplication of explanation, the polarized components passing through the optical element in FIG. 6A are assigned the same reference numerals as (1) to (9) in FIG. 6B, and the explanation thereof will be omitted.

[0064] As shown in FIG. 6A and FIG. 6B, an optical elastic resin layer 130 is provided between the first liquid crystal cell 110 and the second liquid crystal cell 120. Light may also be refracted at the interface between the second substrate 111-2 of the first liquid crystal cell 110 and the optical elastic resin layer 130, or at the interface between the first substrate 121-1 of the second liquid crystal cell 120 and the optical elastic resin layer 130. Therefore, it is preferable that the refractive index of the optical elastic resin of the optical elastic resin layer 130 is close to the refractive index of the second substrate 111-2 of the first liquid crystal cell 110 and the first substrate 121-1 of the second liquid crystal cell 120. In addition, the optical element 10 is disposed close to a light source, and the temperature may increase due to heat from the light source. In this case, in order to mitigate the effects of thermal expansion of the optical elastic resin of the optical elastic resin layer 130, it is preferable that the thickness of the optical elastic resin layer 130 is greater than the inter-substrate distance d between the first substrate 111-1 and the second substrate 111-2 in the first liquid crystal cell 110 or between the first substrate 121-1 and the second substrate 121-2 in the second liquid crystal cell 120.

[0065] The optical element 10 not only diffuses light, but also controls the light distribution by applying an electric potential to each transparent electrode, thereby forming a predetermined light distribution pattern. Some examples of light distribution patterns controlled by the optical element 10 are illustrated below with reference to Figs. 7A to 10. However, the light distribution patterns controlled by the optical element 10 are not limited to these. Note that the signs of the electric potentials (V 11 etc.) are as shown in Table 1.

[0066] [Table 1]

[0067] For convenience, the potentials applied to each transparent electrode are described below as a first potential (variable potential, e.g., low potential 0V and high potential 30V), a second potential (variable potential, e.g., low potential 0V and high potential 30V) that is inverted in phase with the first potential, and a third potential (intermediate potential, e.g., 15V). The third potential is a potential between the low potential and the high potential, and may be a fixed potential or a variable potential. Note that the voltage values ​​are not limited to 0V, 15V, and 30V shown in Figs. 7A to 10.

[0068] [Example 1: Light distribution pattern spreading in the x-axis direction] Fig. 7A is a timing chart showing potentials applied to each transparent electrode included in optical element 10 according to one embodiment of the present invention, and Fig. 7B is a photograph of a light distribution pattern obtained by applying the potentials shown in Fig. 7A to each transparent electrode in optical element 10 according to one embodiment of the present invention.

[0069] In the first liquid crystal cell 110, a first potential and a second potential are applied to the first transparent electrode 112-1 and the second transparent electrode 112-2, respectively. A third potential is applied to each of the third transparent electrode 112-3 and the fourth transparent electrode 112-4. The first potential applied to the first transparent electrode 112-1 and the second potential applied to the second transparent electrode 112-2 are in phase with each other. Therefore, a potential difference (for example, +30V or -30V) is generated between the first transparent electrode 112-1 and the second transparent electrode 112-2. In contrast, there is no potential between the third transparent electrode 112-3 and the fourth transparent electrode 112-4 on the second substrate 111-2 side. In addition, regardless of the state of the third transparent electrode 112-3 and the fourth transparent electrode 112-4 on the second substrate 111-2, a potential of +15V or -15V is generated between them and the first transparent electrode 112-1 or the second transparent electrode 112-2 on the first substrate 111-1, and when viewed in absolute values, there is no bias in the potential difference between one transparent electrode on the first substrate 111-1 and the other transparent electrode on the first substrate 111-1.

[0070] As a result, the liquid crystal molecules on the first substrate 111-1 side change their alignment state in accordance with the potential difference between the first transparent electrode 112-1 and the second transparent electrode 112-2 (see, for example, FIGS. 5A to 5C). On the other hand, the liquid crystal molecules on the second substrate 111-2 side do not change their alignment direction from the initial alignment direction because there is no potential difference between the third transparent electrode 112-3 and the fourth transparent electrode 112-4 and the first substrate 111-1 and the second substrate 111-2 are sufficiently far apart so that they are not affected by the potential on the first substrate 111-1 side. Furthermore, since the third potential applied to the third transparent electrode 112-3 and the fourth transparent electrode 112-4 is an intermediate potential between the first potential and the second potential, even if low potentials and high potentials are alternately applied to the first transparent electrode 112-1 and the second transparent electrode 112-2, no capacitance is accumulated and the orientation state of the liquid crystal molecules on the second substrate 111-2 side does not change.

[0071] In the second liquid crystal cell 120, a first potential and a second potential are applied to the first transparent electrode 122-1 and the second transparent electrode 122-2, respectively. A third potential is applied to each of the third transparent electrode 122-3 and the fourth transparent electrode 122-4. The first potential applied to the first transparent electrode 122-1 and the second potential applied to the second transparent electrode 122-2 are in phase with each other. Therefore, a potential difference (for example, +30V or -30V) is generated between the first transparent electrode 122-1 and the second transparent electrode 122-2. In contrast, there is no potential between the third transparent electrode 122-3 and the fourth transparent electrode 122-4 on the second substrate 121-2 side. In addition, regardless of the state, the third transparent electrode 122-3 and the fourth transparent electrode 122-4 on the second substrate 121-2 side have +15V or -15V between them and the first transparent electrode 122-1 or the second transparent electrode 122-2 on the first substrate 121-1 side, and when viewed in absolute values, there is no bias in the potential difference between one transparent electrode on the first substrate 121-1 side and the other transparent electrode on the first substrate 121-1 side.

[0072] As a result, the liquid crystal molecules on the first substrate 121-1 side change their alignment state in accordance with the potential difference between the first transparent electrode 122-1 and the second transparent electrode 122-2 (see, for example, FIGS. 5A to 5C). On the other hand, the liquid crystal molecules on the second substrate 121-2 side do not change their alignment direction from the initial alignment direction because there is no potential difference between the third transparent electrode 122-3 and the fourth transparent electrode 122-4 and the first substrate 121-1 and the second substrate 121-2 are sufficiently separated from each other so that they are not affected by the potential on the first substrate 121-1 side. Furthermore, since the third potential applied to the third transparent electrode 122-3 and the fourth transparent electrode 122-4 is an intermediate potential between the first potential and the second potential, even if low potentials and high potentials are alternately applied to the first transparent electrode 122-1 and the second transparent electrode 122-2, no capacitance is accumulated and the orientation state of the liquid crystal molecules on the second substrate 121-2 side does not change.

[0073] Also, as shown in FIG. 7A, the potential fluctuations of the first transparent electrode 112-1 and the second transparent electrode 112-2 of the first liquid crystal cell 110 are synchronized with the potential fluctuations of the first transparent electrode 122-1 and the second transparent electrode 122-2 of the second liquid crystal cell 120, respectively.

[0074] When the above-mentioned potentials are applied to the transparent electrodes, the liquid crystal molecules of the liquid crystal layer 113 on the first substrate 111-1 side of the first liquid crystal cell 110 can refract light polarized in the x-axis direction in the x-axis direction. Therefore, the first liquid crystal cell 110 can diffuse light polarized in the x-axis direction.

[0075] In addition, the liquid crystal molecules of the liquid crystal layer 123 on the first substrate 121-1 side of the second liquid crystal cell 120 also refract light polarized in the x-axis direction into the x-axis direction, so that the second liquid crystal cell 120 also diffuses light polarized in the x-axis direction.

[0076] That is, when the potential of each transparent electrode is as shown in FIG. 7A, in the optical element 10, when light is incident from the first substrate 111-1 side of the first liquid crystal cell 110 (meaning that light is irradiated from the lower side of the first liquid crystal cell 110 toward the first substrate 111-1 as shown in FIG. 6A and FIG. 6B; the same applies below), in the process of passing through the first liquid crystal cell 110, the first polarized component 310 having a polarization axis in the x-axis direction is diffused in the x-axis direction on the first substrate 111-1 side, while changing its polarization axis to the y-axis direction. On the other hand, the second polarized component 320 having polarization in the y-axis direction is not diffused, and changes its polarization axis from the y-axis direction to the x-axis direction. Then, these polarized components are incident as they are on the second liquid crystal cell 120. The second polarized component 320, which has its polarization axis changed from the y-axis direction to the x-axis direction without being diffused in the first liquid crystal cell 110, is diffused in the x-axis direction in the process of passing through the second liquid crystal cell 120, and then its polarization axis is changed to the y-axis direction. On the other hand, the first polarized component 310, which has its polarization axis changed from the x-axis direction to the y-axis direction while being diffused in the first liquid crystal cell 110, is changed in its polarization axis from the y-axis direction to the x-axis direction without being diffused. As a result, the light incident on the optical element 10 is diffused in the x-axis direction in the process of passing through the first liquid crystal cell 110 or the second liquid crystal cell 120. Therefore, the light transmitted through the optical element 10 can form a light distribution pattern A spreading in the x-axis direction, as shown in FIG. 7B.

[0077] [Example 2: Light distribution pattern spreading in the y-axis direction] Fig. 8A is a timing chart showing voltages applied to each transparent electrode included in optical element 10 according to one embodiment of the present invention, and Fig. 8B is a photograph of a light distribution pattern obtained by applying the potentials shown in Fig. 8A to each transparent electrode in optical element 10 according to one embodiment of the present invention.

[0078] In the first liquid crystal cell 110, a third potential is applied to each of the first transparent electrode 112-1 and the second transparent electrode 112-2. A first potential and a second potential are applied to the third transparent electrode 112-3 and the fourth transparent electrode 112-4, respectively. The first potential applied to the third transparent electrode 112-3 and the second potential applied to the fourth transparent electrode 112-4 are in phase with each other. Therefore, a potential difference (for example, +30V or -30V) is generated between the third transparent electrode 112-3 and the fourth transparent electrode 112-4. In contrast, there is no potential between the first transparent electrode 112-1 and the second transparent electrode 112-2 on the first substrate 111-1 side. Furthermore, regardless of the state of the first transparent electrode 112-1 and the second transparent electrode 112-2 on the first substrate 111-1 side, a potential of +15V or -15V is generated between them and the third transparent electrode 112-3 or the fourth transparent electrode 112-4 on the second substrate 111-2 side, and when viewed in absolute values, there is no bias in the potential difference between one transparent electrode on the second substrate 111-2 side and the other transparent electrode on the second substrate 111-2 side.

[0079] As a result, the liquid crystal molecules on the second substrate 111-2 side change their alignment state in accordance with the potential difference between the third transparent electrode 112-3 and the fourth transparent electrode 112-4 (see, for example, FIGS. 5A to 5C). On the other hand, the liquid crystal molecules on the first substrate 111-1 side do not change their alignment direction from the initial alignment direction because there is no potential difference between the first transparent electrode 112-1 and the second transparent electrode 112-2 and the first substrate 111-1 and the second substrate 111-2 are sufficiently far apart so that they are not affected by the potential on the second substrate 111-2 side. Furthermore, since the third potential applied to the first transparent electrode 112-1 and the second transparent electrode 112-2 is an intermediate potential between the first potential and the second potential, even if low potentials and high potentials are alternately applied to the third transparent electrode 112-3 and the fourth transparent electrode 112-4, no capacitance is accumulated and the orientation state of the liquid crystal molecules on the first substrate 111-1 side does not change.

[0080] In the second liquid crystal cell 120, a third potential is applied to each of the first transparent electrode 122-1 and the second transparent electrode 122-2. A first potential and a second potential are applied to the third transparent electrode 122-3 and the fourth transparent electrode 122-4, respectively. The first potential applied to the third transparent electrode 122-3 and the second potential applied to the fourth transparent electrode 122-4 are in phase with each other. Therefore, a potential difference (for example, +30V or -30V) is generated between the third transparent electrode 122-3 and the fourth transparent electrode 122-4. In contrast, there is no potential between the first transparent electrode 122-1 and the second transparent electrode 122-2 on the first substrate 121-1 side. Furthermore, regardless of the state of the first transparent electrode 122-1 and the second transparent electrode 122-2 on the first substrate 121-1 side, a potential of +15V or -15V is generated between them and the third transparent electrode 122-3 or the fourth transparent electrode 122-4 on the second substrate 121-2 side, and when viewed in absolute values, there is no bias in the potential difference between one transparent electrode on the second substrate 121-2 side and the other transparent electrode on the second substrate 121-2 side.

[0081] As a result, the liquid crystal molecules on the second substrate 121-2 side change their alignment state in accordance with the potential difference between the third transparent electrode 122-3 and the fourth transparent electrode 122-4 (see, for example, FIGS. 5A to 5C). On the other hand, the liquid crystal molecules on the first substrate 121-1 side do not change their alignment direction from the initial alignment direction because there is no potential difference between the first transparent electrode 122-1 and the second transparent electrode 122-2 and the first substrate 121-1 and the second substrate 121-2 are sufficiently separated from each other so that they are not affected by the potential on the second substrate 121-2 side. Furthermore, since the third potential applied to the first transparent electrode 122-1 and the second transparent electrode 122-2 is an intermediate potential between the first potential and the second potential, even if low potentials and high potentials are alternately applied to the third transparent electrode 122-3 and the fourth transparent electrode 122-4, no capacitance is accumulated and the orientation state of the liquid crystal molecules on the first substrate 121-1 side does not change.

[0082] Also, as shown in FIG. 8B, the potential fluctuations of the third transparent electrode 112-3 and the fourth transparent electrode 112-4 of the first liquid crystal cell 110 are synchronized with the potential fluctuations of the third transparent electrode 122-3 and the fourth transparent electrode 122-4 of the second liquid crystal cell 120, respectively.

[0083] When the above-mentioned potentials are applied to the transparent electrodes, the liquid crystal molecules of the liquid crystal layer 113 on the second substrate 111-2 side of the first liquid crystal cell 110 refract light polarized in the y-axis direction in the y-axis direction. Therefore, the first liquid crystal cell 110 diffuses light polarized in the y-axis direction in the y-axis direction.

[0084] In addition, the liquid crystal molecules of the liquid crystal layer 123 on the second substrate 121-2 side of the second liquid crystal cell 120 also refract light polarized in the y-axis direction in the y-axis direction, so that the second liquid crystal cell 120 also diffuses light polarized in the y-axis direction in the y-axis direction.

[0085] That is, when the potential of each transparent electrode is as shown in FIG. 8A, when light is incident from the first substrate 111-1 side of the first liquid crystal cell 110, the first polarized component 310 having polarization in the x-axis direction is diffused in the y-axis direction on the second substrate 111-2 side while changing the polarization axis from the x-axis direction to the y-axis direction in the process of passing through the first liquid crystal cell 110. On the other hand, the second polarized component 320 having polarization in the y-axis direction is not diffused and changes the polarization axis from the y-axis direction to the x-axis direction. Then, these polarized components are incident on the second liquid crystal cell 120 as they are. The second polarized component 320 having the polarization axis changed from the y-axis direction to the x-axis direction without being diffused in the first liquid crystal cell 110 is diffused in the y-axis direction on the second substrate 121-2 side while changing the polarization axis in the process of passing through the second liquid crystal cell 120. On the other hand, the first polarized component 310, which has its polarization axis changed from the x-axis direction to the y-axis direction while being diffused in the first liquid crystal cell 110, changes its polarization axis from the y-axis direction to the x-axis direction without being diffused. As a result, the light incident on the optical element 10 is diffused in the y-axis direction while passing through the first liquid crystal cell 110 or the second liquid crystal cell 120. Therefore, the light transmitted through the optical element 10 can form a light distribution pattern B spreading in the y-axis direction, as shown in FIG. 8B.

[0086] [Example 3: Cross-shaped light distribution pattern] Fig. 9A is a timing chart showing potentials applied to each transparent electrode included in optical element 10 according to one embodiment of the present invention, and Fig. 9B is a photograph of a light distribution pattern obtained by applying the potentials shown in Fig. 9A to each transparent electrode in optical element 10 according to one embodiment of the present invention.

[0087] In the first liquid crystal cell 110, a first potential and a second potential are applied to the first transparent electrode 112-1 and the second transparent electrode 112-2, respectively. A third potential is applied to each of the third transparent electrode 112-3 and the fourth transparent electrode 112-4. The first potential applied to the first transparent electrode 112-1 and the second potential applied to the second transparent electrode 112-2 are in phase with each other. Therefore, a potential difference (for example, +30V or -30V) is generated between the first transparent electrode 112-1 and the second transparent electrode 112-2. In contrast, there is no potential between the third transparent electrode 112-3 and the fourth transparent electrode 112-4 on the second substrate 111-2 side. In addition, regardless of the state of the third transparent electrode 112-3 and the fourth transparent electrode 112-4 on the second substrate 111-2, a potential of +15V or -15V is generated between them and the first transparent electrode 112-1 or the second transparent electrode 112-2 on the first substrate 111-1, and when viewed in absolute values, there is no bias in the potential difference between one transparent electrode on the first substrate 111-1 and the other transparent electrode on the first substrate 111-1.

[0088] As a result, the liquid crystal molecules on the first substrate 111-1 side change their alignment state in accordance with the potential difference between the first transparent electrode 112-1 and the second transparent electrode 112-2 (see, for example, FIGS. 5A to 5C). On the other hand, the liquid crystal molecules on the second substrate 111-2 side do not change their alignment direction from the initial alignment direction because there is no potential difference between the third transparent electrode 112-3 and the fourth transparent electrode 112-4 and the first substrate 111-1 and the second substrate 111-2 are sufficiently far apart so that they are not affected by the potential on the first substrate 111-1 side. Furthermore, since the third potential applied to the third transparent electrode 112-3 and the fourth transparent electrode 112-4 is an intermediate potential between the first potential and the second potential, even if low potentials and high potentials are alternately applied to the first transparent electrode 112-1 and the second transparent electrode 112-2, no capacitance is accumulated and the orientation state of the liquid crystal molecules on the second substrate 111-2 side does not change.

[0089] In the second liquid crystal cell 120, a third potential is applied to each of the first transparent electrode 122-1 and the second transparent electrode 122-2. A first potential and a second potential are applied to the third transparent electrode 122-3 and the fourth transparent electrode 122-4, respectively. The first potential applied to the third transparent electrode 122-3 and the second potential applied to the fourth transparent electrode 122-4 are in phase with each other. Therefore, a potential difference (for example, +30V or -30V) is generated between the third transparent electrode 122-3 and the fourth transparent electrode 122-4. In contrast, there is no potential between the first transparent electrode 122-1 and the second transparent electrode 122-2 on the first substrate 121-1 side. Furthermore, regardless of the state of the first transparent electrode 122-1 and the second transparent electrode 122-2 on the first substrate 121-1 side, a potential of +15V or -15V is generated between them and the third transparent electrode 122-3 or the fourth transparent electrode 122-4 on the second substrate 121-2 side, and when viewed in absolute values, there is no bias in the potential difference between one transparent electrode on the second substrate 121-2 side and the other transparent electrode on the second substrate 121-2 side.

[0090] As a result, the liquid crystal molecules on the second substrate 121-2 side change their alignment state in accordance with the potential difference between the third transparent electrode 122-3 and the fourth transparent electrode 122-4 (see, for example, FIGS. 5A to 5C). On the other hand, the liquid crystal molecules on the first substrate 121-1 side do not change their alignment direction from the initial alignment direction because there is no potential difference between the first transparent electrode 122-1 and the second transparent electrode 122-2 and the first substrate 121-1 and the second substrate 121-2 are sufficiently separated from each other so that they are not affected by the potential on the second substrate 121-2 side. Furthermore, since the third potential applied to the first transparent electrode 122-1 and the second transparent electrode 122-2 is an intermediate potential between the first potential and the second potential, even if low potentials and high potentials are alternately applied to the third transparent electrode 122-3 and the fourth transparent electrode 122-4, no capacitance is accumulated and the orientation state of the liquid crystal molecules on the first substrate 121-1 side does not change.

[0091] Also, as shown in FIG. 9A, the potential fluctuations of the first transparent electrode 112-1 and the second transparent electrode 112-2 of the first liquid crystal cell 110 are synchronized with the potential fluctuations of the third transparent electrode 122-3 and the fourth transparent electrode 122-4 of the second liquid crystal cell 120, respectively.

[0092] When the above-mentioned potentials are applied to the transparent electrodes, the liquid crystal molecules of the liquid crystal layer 113 on the first substrate 111-1 side of the first liquid crystal cell 110 refract light polarized in the x-axis direction in the x-axis direction. Therefore, the first liquid crystal cell 110 diffuses light polarized in the x-axis direction.

[0093] Furthermore, the liquid crystal molecules of the liquid crystal layer 123 on the second substrate 121-2 side of the second liquid crystal cell 120 refract light polarized in the y-axis direction in the y-axis direction, so that the second liquid crystal cell 120 diffuses light polarized in the y-axis direction in the y-axis direction.

[0094] That is, when the potential of each transparent electrode is as shown in FIG. 9A, when light is incident on the optical element 10 from the first substrate 111-1 side of the first liquid crystal cell 110, the first polarized component 310 having polarization in the x-axis direction is diffused in the x-axis direction on the first substrate 111-1 side while changing the polarization axis from the x-axis direction to the y-axis direction in the process of passing through the first liquid crystal cell 110. On the other hand, the second polarized component 320 having polarization in the y-axis direction is not diffused and changes the polarization axis from the y-axis direction to the x-axis direction. Then, these polarized components are incident on the second liquid crystal cell 120 as they are. The second polarized component 320 having its polarization axis changed from the y-axis direction to the x-axis direction without being diffused in the first liquid crystal cell 110 is diffused in the y-axis direction on the second substrate 121-2 side while changing the polarization axis from the x-axis direction to the y-axis direction in the process of passing through the second liquid crystal cell 120. On the other hand, the first polarized component 310, which has its polarization axis changed from the x-axis direction to the y-axis direction while being diffused in the first liquid crystal cell 110, changes its polarization axis from the y-axis direction to the x-axis direction without being diffused. In this manner, the light incident on the optical element 10 is diffused in the x-axis direction while the first polarized component 310 passes through the first liquid crystal cell 110, and is diffused in the y-axis direction while the second polarized component 320 passes through the second liquid crystal cell 120. Therefore, the light transmitted through the optical element 10 can form a light distribution pattern C that spreads in a cross shape, as shown in FIG. 9B.

[0095] As described above, the cross-shaped light distribution pattern is formed by mainly diffusing the first polarized component 310 by applying the potential shown in FIG. 9A to each transparent electrode, but the cross-shaped light distribution pattern can be formed by diffusing the second polarized component 320 by changing the potential supplied to each transparent electrode. Specifically, in the first liquid crystal cell 110, the first potential and the second potential are applied to the third transparent electrode 112-3 and the fourth transparent electrode 112-4, respectively, and the third potential is applied to the first transparent electrode 112-1 and the second transparent electrode 112-2, respectively. In the second liquid crystal cell 120, the first potential and the second potential are applied to the first transparent electrode 122-1 and the second transparent electrode 122-2, respectively, and the third potential is applied to the third transparent electrode 122-3 and the fourth transparent electrode 122-4, respectively. As a result, a cross-shaped light distribution pattern is formed by diffusing mainly the second polarized component 320.

[0096] [Example 4: Light distribution pattern spreading in a rectangle] FIG. 10 is a timing chart showing voltages applied to each transparent electrode included in the optical element 10 according to one embodiment of the present invention.

[0097] In the first liquid crystal cell 110, a first potential is applied to each of the first transparent electrode 112-1 and the third transparent electrode 112-3. A second potential is applied to each of the second transparent electrode 112-2 and the fourth transparent electrode 112-4. The first potential applied to the first transparent electrode 112-1 and the third transparent electrode 112-3 and the second potential applied to the second transparent electrode 112-2 and the fourth transparent electrode 112-4 are in phase with each other. Therefore, a potential difference (for example, +30V or -30V) is generated between the first transparent electrode 112-1 and the second transparent electrode 112-2 and between the third transparent electrode 112-3 and the fourth transparent electrode 112-4. Furthermore, a potential difference (for example, +30 V or −30 V) is generated between the first transparent electrode 112-1 and the fourth transparent electrode 112-4 and between the second transparent electrode 112-2 and the third transparent electrode 112-3.

[0098] As a result, the liquid crystal molecules on the first substrate 111-1 side change their alignment state in accordance with the potential difference between the first transparent electrode 112-1 and the second transparent electrode 112-2 (see, for example, FIGS. 5A to 5C). The liquid crystal molecules on the second substrate 111-2 side change their alignment state in accordance with the potential difference between the third transparent electrode 112-3 and the fourth transparent electrode 112-4 (see, for example, FIGS. 5A to 5C). Note that, since the first substrate 111-1 and the second substrate 111-2 are sufficiently separated from each other, the influence of the first potential applied to the third transparent electrode 112-3 or the second potential applied to the fourth transparent electrode 112-4 on the liquid crystal molecules on the first substrate 111-1 side is slight. Similarly, the influence of the first potential applied to the first transparent electrode 112-1 or the second potential applied to the second transparent electrode 112-2 on the liquid crystal molecules on the second substrate 111-2 side is slight.

[0099] In the second liquid crystal cell 120, a first potential is applied to each of the first transparent electrode 122-1 and the third transparent electrode 122-3. A second potential is applied to each of the second transparent electrode 122-2 and the fourth transparent electrode 122-4. The first potential applied to the first transparent electrode 122-1 and the third transparent electrode 122-3 and the second potential applied to the second transparent electrode 122-2 and the fourth transparent electrode 122-4 are in phase with each other. Therefore, a potential difference (for example, +30V or -30V) is generated between the first transparent electrode 122-1 and the second transparent electrode 122-2 and between the third transparent electrode 122-3 and the fourth transparent electrode 122-4. Furthermore, a potential difference (for example, +30 V or −30 V) is generated between the first transparent electrode 122-1 and the fourth transparent electrode 122-4 and between the second transparent electrode 122-2 and the third transparent electrode 122-3.

[0100] As a result, the liquid crystal molecules on the first substrate 121-1 side change their alignment state in accordance with the potential difference between the first transparent electrode 122-1 and the second transparent electrode 122-2 (see, for example, FIGS. 5A to 5C). The liquid crystal molecules on the second substrate 121-2 side change their alignment state in accordance with the potential difference between the third transparent electrode 122-3 and the fourth transparent electrode 122-4 (see, for example, FIGS. 5A to 5C). Note that, since the first substrate 121-1 and the second substrate 121-2 are sufficiently separated from each other, the influence of the first potential applied to the third transparent electrode 122-3 or the second potential applied to the fourth transparent electrode 122-4 on the liquid crystal molecules on the first substrate 121-1 side is slight. Similarly, the influence of the first potential applied to the first transparent electrode 122-1 or the second potential applied to the second transparent electrode 122-2 on the liquid crystal molecules on the second substrate 121-2 side is slight.

[0101] 10, the potential fluctuations of the first transparent electrode 112-1 and the third transparent electrode 112-3 of the first liquid crystal cell 110 and the potential fluctuations of the first transparent electrode 122-1 and the third transparent electrode 122-3 of the second liquid crystal cell 120 are synchronized with each other. Also, the potential fluctuations of the second transparent electrode 112-2 and the fourth transparent electrode 112-4 of the first liquid crystal cell 110 and the potential fluctuations of the second transparent electrode 122-2 and the fourth transparent electrode 122-4 of the second liquid crystal cell 120 are synchronized with each other.

[0102] When the above-mentioned potentials are applied to the transparent electrodes, the liquid crystal molecules of the liquid crystal layer 113 on the first substrate 111-1 side of the first liquid crystal cell 110 refract light polarized in the x-axis direction into the x-axis direction. Also, the liquid crystal molecules of the liquid crystal layer 113 on the second substrate 111-2 side of the first liquid crystal cell 110 refract light polarized in the y-axis direction into the y-axis direction. Therefore, the first liquid crystal cell 110 diffuses light polarized in the x-axis direction in both the x-axis and y-directions.

[0103] Moreover, the liquid crystal molecules of the liquid crystal layer 123 on the first substrate 121-1 side of the second liquid crystal cell 120 refract light polarized in the x-axis direction into the x-axis direction. Moreover, the liquid crystal of the liquid crystal layer 123 on the second substrate 121-2 side of the second liquid crystal cell 120 refracts light polarized in the y-axis direction into the y-axis direction. Therefore, the second liquid crystal cell 120 also diffuses light polarized in the x-axis direction in the x-axis and y directions.

[0104] That is, when the potential of each transparent electrode is as shown in FIG. 10, in the optical element 10, when light is incident from the first substrate 111-1 side of the first liquid crystal cell 110, the first polarized component 310 having polarization in the x-axis direction is diffused in the x-axis direction on the first substrate 111-1 side while changing the polarization axis from the x-axis direction to the y-axis direction in the process of passing through the first liquid crystal cell 110. Also, the first polarized component 310 whose polarization axis has been changed from the x-axis direction to the y-axis direction is diffused in the y-axis direction on the second substrate 111-2 side. On the other hand, the second polarized component 320 having polarization in the y-axis direction is not diffused and changes the polarization axis from the y-axis direction to the x-axis direction. Then, these polarized components are incident on the second liquid crystal cell 120 as they are. The second polarized component 320, which has its polarization axis changed from the y-axis direction to the x-axis direction without being diffused in the first liquid crystal cell 110, changes its polarization axis from the x-axis direction to the y-axis direction while being diffused in the x-axis direction on the first substrate 121-1 side in the process of passing through the second liquid crystal cell 120. The second polarized component 320, which has its polarization axis changed from the x-axis direction to the y-axis direction, is diffused in the y-axis direction on the second substrate 121-2 side. On the other hand, the first polarized component 310, which has its polarization axis changed from the x-axis direction to the y-axis direction while being diffused in the first liquid crystal cell 110, changes its polarization axis from the y-axis direction to the x-axis direction without being diffused. In this way, the light incident on the optical element 10 is diffused in the x-axis and y-axis directions while the first polarized component 310 passes through the first liquid crystal cell 110, and is diffused in the x-axis and y-axis directions while the second polarized component 320 passes through the second liquid crystal cell 120. Therefore, the light transmitted through the optical element 10 can form a light distribution pattern that spreads in a rectangular shape.

[0105] Although several light distribution patterns have been exemplified above, the light distribution angle, which indicates the distribution of light distribution, can be controlled by the magnitude of the voltage applied to the transparent electrodes. For example, by increasing the voltage applied to the transparent electrodes, the light distribution angle becomes larger, and a light distribution pattern in which the light is more diffused can be obtained. The light distribution angle can also be controlled by, for example, the distance d between the substrates or the pitch p.

[0106] [4. Correlation between board distance and pitch] The correlation between the substrate distance d and the pitch p will be described in detail with reference to FIG.

[0107] FIG. 11 is a graph showing the relative front luminance (relative luminance at 0 degrees) versus d / p in the liquid crystal cell of the optical element 10 according to one embodiment of the present invention. The substrate distance d is the distance between the first substrate 111-1 and the second substrate 111-2 of the first liquid crystal cell 110 (or the distance between the first substrate 121-1 and the second substrate 121-2 of the second liquid crystal cell 120) as shown in FIGS. 4A to 5B. The pitch p is the first pitch p1 shown in FIG. 3A (or the second pitch p2 shown in FIG. 3B). The relative front luminance is the luminance of the light that is incident from the first substrate 111-1 and emitted from the second substrate 111-2 in the perpendicular direction (0 degrees) of the second substrate 111-2. The graph shown in FIG. 11 is normalized with the luminance of the light when the optical element 10 is not present (when there is only a light source) being 1. Therefore, the y-axis of the graph shown in FIG. 11 can also be said to be the relative luminance ratio when the luminance in the absence of the optical element 10 is taken as 1.

[0108] 11 was obtained, the first transparent electrode 112-1 and the second transparent electrode 112-2 were formed on the first substrate 111-1, but the third transparent electrode 112-3 and the fourth transparent electrode 112-4 were not formed on the second substrate 111-2. When measuring the luminance, a low potential (0V) was applied to the first transparent electrode 112-1, and a high potential (30V) was applied to the second transparent electrode 112-2.

[0109] As shown in FIG. 11, the relative front luminance decreases as d / p increases, but the rate of decrease in the relative front luminance is significantly different between d / p<1 and d / p≧1. At d / p<1, the relative front luminance decreases significantly as d / p approaches 1, but the measured front luminance ratio is about 0.2 to 0.4. This indicates that the luminance decreases due to the diffusion of light by the liquid crystal cell, but the diffusion is not yet sufficient. In contrast, at d / p≧1, the relative front luminance becomes 0.1 or less, and the relative front luminance remains stable even if d / p is increased thereafter. This indicates that the diffusion of light by the liquid crystal cell is sufficient at d / p≧1. That is, excellent light diffusion is obtained at d / p≧1. Therefore, in the optical element 10, it is preferable that the substrate distance d and the pitch p satisfy d / p≧1, and it is more preferable that they satisfy d / p≧2.

[0110] Furthermore, the transparent electrode material has a high refractive index, which may affect the transmittance of the liquid crystal cell. Therefore, it is preferable that the width of the transparent electrode is small. In other words, it is preferable that the inter-electrode distance b (the first inter-electrode distance b1 or the second inter-electrode distance b2 shown in FIG. 3A or FIG. 3B) is equal to or smaller than the width a of the transparent electrode (the first width a1 or the second width a2 shown in FIG. 3A or FIG. 3B). For example, when expressing the inter-electrode distance b in relation to the pitch p, it is preferable that p / 2≦b is satisfied.

[0111] As described above, the optical element 10 of this embodiment has two liquid crystal cells, and by controlling the voltage applied to each transparent electrode, the light distribution or light distribution pattern of the light passing through the optical element 10 can be easily controlled.

[0112] <Second embodiment> The configuration of an illumination device 20 according to an embodiment of the present invention will be described with reference to FIG.

[0113] Fig. 12 is a schematic diagram showing a configuration of an illumination device 20 according to one embodiment of the present invention. As shown in Fig. 12, the illumination device 20 includes an optical element 10, a light source 210, a convex lens 220, and a reflector 230. The convex lens 220 is disposed between the optical element 10 and the light source 210. The reflector 230 is disposed so as to surround the space between the light source 210 and the convex lens 220.

[0114] The light source 210 can emit light. For example, a light bulb, a fluorescent lamp, a cold cathode fluorescent lamp, a light emitting diode (LED), or a laser diode (LD) can be used as the light source 210. Preferably, the light source 210 of the lighting device 20 is an LED. The lighting device 20 using an LED with high light emitting efficiency as the light source 210 has high brightness and low power consumption. The LED and LD include an organic light emitting diode (OLED) and an organic laser diode (LD), respectively.

[0115] The convex lens 220 can collect the light emitted from the light source 210 and make the collected light incident on the optical element 10.

[0116] The reflector 230 can reflect the light emitted from the light source 210 and make the reflected light incident on the convex lens. The shape of the reflector 230 is, for example, substantially conical, but is not limited to this. The surface of the reflector 230 may be flat or curved.

[0117] Furthermore, the lighting device 20 may include a control unit that controls the voltage applied to the transparent electrodes, so that various light orientation patterns can be formed.

[0118] As described above, since the lighting device 20 according to this embodiment includes the optical element 10, the light distribution or light distribution pattern of the light emitted from the lighting device 20 can be easily controlled.

[0119] Within the scope of the concept of the present invention, those skilled in the art may make various modifications and alterations, and it is understood that these modifications and alterations also fall within the scope of the present invention. For example, those in which a person skilled in the art appropriately adds, deletes, or modifies components of the above-mentioned embodiments, or adds, omits, or modifies conditions of steps, are also included in the scope of the present invention as long as they include the gist of the present invention.

[0120] Furthermore, other effects and advantages brought about by the aspects of this embodiment that are obvious from the description in this specification or that can be appropriately thought of by a person skilled in the art are naturally understood to be brought about by the present invention. [Explanation of symbols]

[0121] 10: optical element, 20: lighting device, 110: first liquid crystal cell, 111-1: first substrate, 111-2: second substrate, 112-1: first transparent electrode, 112-2: second transparent electrode, 112-3: third transparent electrode, 112-4: fourth transparent electrode, 113: liquid crystal layer, 114-1: first alignment film, 114-2: second alignment film, 115: sealing material, 116-1: first wiring, 116-2: second wiring, 116-3: third wiring, 116-4: fourth wiring, 116-5: fifth wiring, 116-6: sixth wiring, 120: second liquid crystal cell, 121-1: first substrate, 121-2: second substrate, 122-1: first transparent electrode, 122-2: second transparent electrode, 122-3: third transparent electrode, 122-4: fourth transparent electrode, 123: liquid crystal layer, 124-1: first alignment film, 124-2: second alignment film, 125: sealing material, 130: optical elastic resin layer, 210: light source, 220: convex lens, 230: reflector, 310: first polarized light component, 320: second polarized light component

Claims

1. An optical element comprising: a first liquid crystal cell on which light including a first polarized component having a first polarization axis in a first direction and a second polarized component having a second polarization axis in a second direction intersecting the first direction is incident; and a second liquid crystal cell stacked on the first liquid crystal cell so that the light after passing through the first liquid crystal cell is incident on the second liquid crystal cell, Each of the first liquid crystal cell and the second liquid crystal cell comprises: A first substrate; a first transparent electrode and a second transparent electrode arranged alternately in the first direction on the first substrate, each of the first transparent electrodes extending in the second direction; a first alignment film covering the first transparent electrode and the second transparent electrode and having an alignment direction in the first direction; A second substrate; third and fourth transparent electrodes arranged alternately in the second direction on the second substrate, each extending in the first direction; a second alignment film covering the third transparent electrode and the fourth transparent electrode and having an alignment direction in the second direction; a liquid crystal layer between the first substrate and the second substrate; liquid crystal molecules in the liquid crystal layer are aligned in accordance with the alignment direction of the first alignment film and the alignment direction of the second alignment film such that a major axis changes from the first direction to the second direction from the first substrate side to the second substrate side; the second substrate of the first liquid crystal cell is adjacent to the first substrate of the second liquid crystal cell; In an off state in which no potential is applied to the first transparent electrode to the fourth transparent electrode of each of the first liquid crystal cell and the second liquid crystal cell, in each of the first liquid crystal cell and the second liquid crystal cell, when the light passes through the liquid crystal layer from the first substrate to the second substrate, the polarization axis of each of the first polarization component and the second polarization component changes such that the first polarization axis and the second polarization axis change to the second polarization axis and the first polarization axis, respectively; In an on-state in which a potential difference is generated between the first transparent electrode and the second transparent electrode of each of the first liquid crystal cell and the second liquid crystal cell, In the first liquid crystal cell, when the light passes through the liquid crystal layer from the first substrate to the second substrate, the polarization axes of the first polarization component and the second polarization component change so that the first polarization axis and the second polarization axis change to the second polarization axis and the first polarization axis, respectively, and the first polarization component is diffused in the second direction on the second substrate side, An optical element in which, in the second liquid crystal cell, when the light passes through the liquid crystal layer from the first substrate to the second substrate, the polarization axes of the first polarization component and the second polarization component change so that the first polarization axis and the second polarization axis change to the second polarization axis and the first polarization axis, respectively, and the second polarization component is diffused in the second direction on the second substrate side.

2. The optical element of claim 1 , wherein the second direction is orthogonal to the first direction.

3. a substrate distance d between the first substrate and the second substrate, and a first pitch p between the first transparent electrode and the second transparent electrode; １ By d / p １ 3. The optical element according to claim 1, wherein the optical element satisfies .gtoreq.

1.

4. d / p １ The optical element according to claim 3 , which satisfies ≧2.

5. The first pitch p １ and a first inter-electrode distance b between the first transparent electrode and the second transparent electrode. １ By p １ / 2≦b １ The optical element according to claim 3 or 4, which satisfies the above.

6. The distance d between the substrates and the second pitch p between the third transparent electrode and the fourth transparent electrode ２ is d / p ２ 6. The optical element according to claim 3, wherein .gtoreq.1 is satisfied.

7. d / p ２ The optical element according to claim 6 , which satisfies ≧2.

8. The second pitch p ２ and a second inter-electrode distance b between the third transparent electrode and the fourth transparent electrode. ２ By p ２ / 2≦b ２ The optical element according to claim 6 or 7, which satisfies the above.

9. 9. The optical element according to claim 1, wherein the second substrate of the first liquid crystal cell and the first substrate of the second liquid crystal cell are adjacent to each other via an optical elastic resin layer.

10. 10. The optical element according to claim 1, wherein different voltages are applied to the first transparent electrode, the second transparent electrode, the third transparent electrode, and the fourth transparent electrode.

11. In plan view, the first transparent electrode of the first liquid crystal cell and the first transparent electrode of the second liquid crystal cell overlap each other in an extension direction; the second transparent electrode of the first liquid crystal cell and the second transparent electrode of the second liquid crystal cell overlap each other in an extension direction; the third transparent electrode of the first liquid crystal cell and the third transparent electrode of the second liquid crystal cell overlap each other in an extension direction; 11 . The optical element according to claim 1 , wherein the fourth transparent electrode of the first liquid crystal cell and the fourth transparent electrode of the second liquid crystal cell overlap with each other in an extension direction.

12. In plan view, the first transparent electrode of the first liquid crystal cell and the first transparent electrode of the second liquid crystal cell are overlapped so as to substantially coincide with each other in an extension direction; the second transparent electrode of the first liquid crystal cell and the second transparent electrode of the second liquid crystal cell are overlapped so as to substantially coincide with each other in an extension direction; the third transparent electrode of the first liquid crystal cell and the third transparent electrode of the second liquid crystal cell are overlapped so as to substantially coincide with each other in an extension direction; 11. The optical element according to claim 1, wherein the fourth transparent electrode of the first liquid crystal cell and the fourth transparent electrode of the second liquid crystal cell overlap each other so as to be substantially aligned in the extension direction.

13. A light source; An illumination device comprising: an optical element according to claim 1 .

14. The illumination device of claim 13 , further comprising a convex lens between the light source and the optical element.

15. 15. The lighting device according to claim 13, further comprising a reflector that reflects the light emitted from the light source so as to be incident on the optical element.

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