Ray direction control element, display device, and manufacturing method of ray direction control element

Abstract

To provide a ray direction control element having high transmittance, a display device, and a manufacturing method of the ray direction control element in a state in which an angle distribution of emission light is wide.SOLUTION: A ray direction control element 100 includes: a light transmissive region 30 sandwiched by a first light transmissive substrate 10 and a second light transmissive substrate 20; a light absorption region 40 positioned in a region to the light transmissive region 30; a light transmissive dispersion medium 52 sealed into the light absorption region 40; and an electrophoresis particle 54 dispersed to the light transmissive dispersion medium 52. The light transmissive region 30 includes: a first light transmissive region 32 extending toward the second light transmissive substrate 20 from the first light transmissive substrate 10; and a second light transmissive region 34 extending toward the second light transmissive substrate 20 from the first light transmissive region 32. A height H1 of the first light transmissive region 32 is lower than a height H2 of the second light transmissive region 34 and a width D1 of the first light transmissive region 32 is larger than a width D2 of the second light transmissive region 34.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a light ray direction control element, a display device, and a method for manufacturing a light ray direction control element.

Background Art

[0002] A light ray direction control element that controls the emission range of transmitted light is known. For example, Patent Document 1 discloses a first and a second transparent substrate arranged such that their main surfaces face each other, a conductive light-shielding pattern arranged on the first transparent substrate, a transparent conductive film arranged on the second transparent substrate, a plurality of light-transmitting regions arranged on the first transparent substrate, and an electrophoresis element arranged between adjacent light-transmitting regions and composed of light-shielding electrophoresis particles and a permeable dispersant. In the optical element of Patent Document 1, by adjusting the potential difference between the conductive light-shielding pattern and the transparent conductive film, the dispersion state of the electrophoresis particles is changed, and the emission range of the light transmitted through the light-transmitting region and the dispersant is changed.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the optical element of Patent Document 1, a wide viewing angle state (wide emission range) is realized by aggregating electrophoresis particles near the conductive light-shielding pattern. However, in the wide viewing angle state, it is desired to increase the transmittance of the optical element. In order to increase the transmittance of the optical element in the wide viewing angle state, it is possible to narrow the region where the electrophoresis particles are aggregated (that is, the interval between the light-transmitting regions) and increase the aperture ratio of the optical element in the wide viewing angle state.

[0005] On the other hand, in order to change the range of light emission, it is also necessary to form light-transmitting regions with a high aspect ratio. In Patent Document 1, since light-transmitting regions are formed from a photosensitive resin (photoresist), it is difficult to form light-transmitting regions with a high aspect ratio at narrower intervals.

[0006] This disclosure is made in view of the above circumstances and aims to provide a light ray direction control element, a display device, and a method for manufacturing a light ray direction control element that have high transmittance when the angular distribution of emitted light is wide. [Means for solving the problem]

[0007] To achieve the above objective, the ray direction control element relating to the first aspect is: A first translucent substrate having a first translucent electrode on its main surface, A second translucent substrate facing the first translucent substrate and having a second translucent electrode on its main surface facing the main surface of the first translucent substrate, A plurality of light-transmitting regions are arranged in a predetermined direction and sandwiched between the first light-transmitting substrate and the second light-transmitting substrate, A plurality of light-absorbing regions located between the light-transmitting regions, A light-transmitting dispersion medium is enclosed in the aforementioned light-absorbing region, The invention comprises electrophoretic particles that absorb light, are dispersed in the light-transmitting dispersion medium, and whose dispersion state changes depending on the applied voltage, Each of the light-transmitting regions includes a first light-transmitting region extending perpendicularly to the main surface of the first light-transmitting substrate from the main surface of the first light-transmitting substrate toward the second light-transmitting substrate, and a second light-transmitting region extending perpendicularly to the main surface of the first light-transmitting substrate from the upper surface of the first light-transmitting region toward the second light-transmitting substrate. Each of the light-absorbing regions has a first light-absorbing region located between the first light-transmitting regions and a second light-absorbing region located between the second light-transmitting regions. The height of the first light-transmitting region from the main surface of the first light-transmitting substrate is lower than the height of the second light-transmitting region from the top surface of the first light-transmitting region. When viewed in cross-section with respect to the main surface of the first translucent substrate, including the predetermined direction, the width of the first translucent region is wider than the width of the second translucent region.

[0008] The display device relating to the second aspect is, The light ray direction control element described above, It is equipped with a display panel, The light ray direction control element is located on the display surface of the display panel.

[0009] The display device relating to the third aspect is, The light ray direction control element described above, A transmissive liquid crystal display panel, The system comprises a backlight positioned on the opposite side of the display surface of the transmissive liquid crystal display panel and supplying light to the transmissive liquid crystal display panel, The light ray direction control element is positioned between the transmissive liquid crystal display panel and the backlight.

[0010] The method for manufacturing a ray direction control element relating to the fourth aspect is: A step of preparing a mold having a mold substrate, a plurality of first column portions provided perpendicular to the main surface of the mold substrate and arranged in a predetermined direction, and a second column portion provided perpendicular to the main surface of the mold substrate on the upper surface of each of the plurality of first column portions, The process of filling the mold with a translucent resin, A step of pressing the main surface of a first translucent substrate having a first translucent electrode on its main surface against the translucent resin exposed between the second columnar portion and the second columnar portion, A step of curing the translucent resin by pressing the main surface of the first translucent substrate against it, A step of releasing the mold from the cured translucent resin to form a plurality of translucent layers on the main surface of the first translucent substrate, each layer having a first translucent layer having a shape corresponding to the shape of the space between adjacent second column portions, and a second translucent layer having a shape corresponding to the shape of the space between adjacent first column portions. A step of pressing a second translucent substrate onto the plurality of translucent layers, the second translucent substrate having a second translucent electrode on the main surface facing the first translucent substrate and the main surface facing the main surface of the first translucent substrate, The process includes filling the light-transmitting layers with a light-transmitting dispersion medium in which electrophoretic particles that absorb light and whose dispersion state changes depending on the applied voltage are dispersed, The height of the space between adjacent second columns is lower than the height of the space between adjacent first columns. When viewed in cross-section with respect to the main surface of the mold substrate, including the predetermined direction, the width of the space between adjacent second column portions is wider than the width of the space between adjacent first column portions.

[0011] The method for manufacturing a ray direction control element relating to the fifth aspect is: A step of forming a light-shielding layer at predetermined intervals on the main surface of a first light-transmitting substrate having a first light-transmitting electrode on its main surface, A step of laminating a first layer, formed from a photosensitive light-transmitting material and covering the light-shielding layer, onto the main surface of the first light-transmitting substrate to a predetermined first thickness, A step of exposing the first layer from the side of the first light-transmitting substrate, A step of laminating a second layer, formed from a photosensitive translucent material, onto the exposed first layer, with a predetermined second thickness that is greater than the predetermined first thickness, A step of exposing the region located between the light-shielding layers of the second layer when viewed from the side of the second layer, with a width narrower than the predetermined interval of the light-shielding layers, The process involves developing the exposed first layer and the exposed second layer to form a plurality of light-transmitting layers on the main surface of the first light-transmitting substrate, A step of pressing a second translucent substrate onto the plurality of translucent layers, the second translucent substrate having a second translucent electrode on the main surface facing the first translucent substrate and the main surface facing the main surface of the first translucent substrate, The process includes filling the light-transmitting layers with a light-transmitting dispersion medium in which electrophoretic particles that absorb light and whose dispersion state changes depending on the applied voltage are dispersed. [Effects of the Invention]

[0012] According to the present disclosure, since the height of the first light-transmitting region is lower than the height of the second light-transmitting region and the width of the first light-transmitting region is wider than the width of the second light-transmitting region, the first light-absorbing region located between the first light-transmitting regions can be narrowed in plan view, and the transmittance of the light-ray direction control element in a state where the angular distribution of the emitted light is wide can be improved.

Brief Description of the Drawings

[0013] [Figure 1] It is a cross-sectional view showing a light-ray direction control element according to Embodiment 1. [Figure 2] It is a schematic view showing a display device according to Embodiment 1. [Figure 3] It is a perspective view showing a first light-transmitting region, a second light-transmitting region, a first light-absorbing region, and a second light-absorbing region according to Embodiment 1. [Figure 4] It is a schematic view showing a narrow viewing angle mode according to Embodiment 1. [Figure 5] It is a view showing the angular distribution of the emitted light of the light-ray direction control element in a plane parallel to the XZ plane according to Embodiment 1. [Figure 6] It is a schematic view showing a first wide viewing angle mode according to Embodiment 1. [Figure 7] It is a plan view showing the light-ray direction control element in the first wide viewing angle mode according to Embodiment 1. [Figure 8] It is a flowchart showing a method for manufacturing a light-ray direction control element according to Embodiment 1. [Figure 9] It is a schematic view showing a mold according to Embodiment 1. [Figure 10] It is a schematic view showing a mold, a light-transmissive resin, according to Embodiment 1. [Figure 11] It is a schematic view showing a mold, a light-transmissive resin, and a first light-transmissive substrate according to Embodiment 1. [Figure 12] It is a schematic view showing a first light-transmissive substrate and a light-transmissive layer according to Embodiment 1. [Figure 13] It is a schematic view showing a first light-transmissive substrate, a light-transmissive layer, and a second light-transmissive substrate according to Embodiment 1. [Figure 14]This is a schematic diagram showing the second wide-field mode according to Embodiment 2. [Figure 15] This figure shows the angular distribution of the emitted light from the ray direction control element in a plane parallel to the XZ plane, according to Embodiment 2. [Figure 16] This is a cross-sectional view showing a ray direction control element according to Embodiment 3. [Figure 17] This is a cross-sectional view showing a ray direction control element according to Embodiment 4. [Figure 18] This is a schematic diagram showing the maximum emission angle according to Embodiment 5. [Figure 19] This figure shows the height of the second light-transmitting region and the maximum emission angle according to Embodiment 5. [Figure 20] This is a flowchart showing a method for manufacturing a light ray direction control element according to Embodiment 6. [Figure 21] This is a schematic diagram showing the light-shielding layer according to Embodiment 6. [Figure 22] This is a schematic diagram showing the first layer according to Embodiment 6. [Figure 23] This is a schematic diagram showing the exposure of the first layer according to Embodiment 6. [Figure 24] This is a schematic diagram showing the second layer according to Embodiment 6. [Figure 25] This is a schematic diagram showing the exposure of the second layer according to Embodiment 6. [Figure 26] This is a schematic diagram showing the first translucent substrate and translucent layer according to Embodiment 6. [Figure 27] This is a schematic diagram showing a modified light ray direction control element. [Figure 28] This is a schematic diagram showing the first light-transmitting region related to a modified example. [Figure 29] This is a schematic diagram showing the first light-transmitting region related to a modified example. [Figure 30] This is a schematic diagram showing the first light-transmitting region related to a modified example. [Figure 31] This is a schematic diagram illustrating the retention of electrophoretic particles. [Figure 32] This is a schematic diagram showing the first light-transmitting region related to a modified example. [Figure 33]This is a schematic diagram showing the first light-transmitting region related to a modified example. [Figure 34] This is a schematic diagram showing the first light-transmitting region related to a modified example. [Figure 35] This is a schematic diagram showing a modified display device. [Figure 36] This is a schematic diagram showing a modified display device. [Modes for carrying out the invention]

[0014] The ray direction control element and display device according to the embodiment will be described below with reference to the drawings.

[0015] <Embodiment 1> Referring to Figures 1 to 13, the light direction control element 100 and the display device 300 according to this embodiment will be described. As shown in Figure 1, the light direction control element 100 comprises a first translucent substrate 10, a second translucent substrate 20, a translucent region 30, and a light absorption region 40. The light absorption region 40 contains a translucent dispersion medium 52 and electrophoretic particles 54. The translucent region 30 has a first translucent region 32 and a second translucent region 34. The light absorption region 40 also has a first light absorption region 42 and a second light absorption region 44. In the light direction control element 100, the dispersion state of the electrophoretic particles in the translucent dispersion medium 52 changes due to the voltage applied to the electrophoretic particles 54 from an external power source (not shown), and the angular distribution of the emitted light from the light direction control element 100 changes. For ease of understanding, in this specification, the rightward direction (rightward direction on the paper) of the light ray direction control element 100 in Figure 1 will be described as the +X direction, the upward direction (upward direction on the paper) as the +Z direction, and the direction perpendicular to the +X and +Z directions (backward direction on the paper) as the +Y direction. Furthermore, the X direction will also be described as the left-right direction, and the Z direction as the up-down direction.

[0016] As shown in Figure 2, the light ray direction control element 100, together with the display panel 210, constitutes the display device 300. The display device 300 is mounted on smartphones, laptop computers, vehicles, information displays, etc. The display panel 210 displays characters, images, etc. The display panel 210 is a liquid crystal display panel, an organic EL (Electro Luminescence) display panel, a micro LED (Light Emitting Diode) display panel, etc.

[0017] The light ray direction control element 100 controls the angular distribution of light (angular distribution of emitted light) emitted from the display panel 210 and transmitted through the light ray direction control element 100. The light ray direction control element 100 is positioned on the display surface of the display panel 210.

[0018] Returning to Figure 1, the first translucent substrate 10 of the light ray direction control element 100 transmits visible light. The first translucent substrate 10 is, for example, a flat glass substrate. The first translucent substrate 10 has a first translucent electrode 12 on its first main surface 10a. In this embodiment, the first translucent electrode 12 is formed from ITO (Indium Tin Oxide) over the entire surface of the first main surface 10a. An insulating layer (not shown) is also provided on the first translucent electrode 12. The insulating layer is, for example, formed from silicon oxide (SiO2).

[0019] The second translucent substrate 20 of the light ray direction control element 100 transmits visible light, similar to the first translucent substrate 10. The second translucent substrate 20 is, for example, a flat glass substrate. The second translucent substrate 20 has a second translucent electrode 22 on the first main surface 20a. The second translucent electrode 22 is formed from ITO over the entire surface of the first main surface 20a. An insulating layer is also provided on the second translucent electrode 22.

[0020] The second translucent substrate 20 faces the first translucent substrate 10. In this embodiment, the first main surface 10a of the first translucent substrate 10 and the first main surface 20a of the second translucent substrate 20 face each other.

[0021] The light-transmitting region 30 of the light ray direction control element 100 is a region that transmits visible light. The light-transmitting region 30 is aligned in the X direction and is sandwiched between the first translucent substrate 10 and the second translucent substrate 20. The light-transmitting region 30 is, for example, a translucent layer formed from a translucent resin. As shown in Figure 1, the light-transmitting region 30 has a first translucent region 32 and a second translucent region 34. In this embodiment, the X direction corresponds to a predetermined direction.

[0022] The first light-transmitting region 32 is provided on the first main surface 10a of the first light-transmitting substrate 10. As shown in Figures 1 and 3, the first light-transmitting region 32 has a rectangular parallelepiped shape that extends perpendicularly to the first main surface 10a of the first light-transmitting substrate 10 (i.e., extends in the +Z direction) toward the second light-transmitting substrate 20 from the first main surface 10a of the first light-transmitting substrate 10. The first light-transmitting region 32 also extends in the Y direction (depth direction). The first light-transmitting regions 32 are arranged in the X direction at intervals corresponding to the width D3 of the first light-absorbing region 42, which will be described later. Note that the interval of the first light-transmitting regions 32 refers to the interval between the sides of adjacent first light-transmitting regions 32.

[0023] The height H1 of the first light-transmitting region 32 from the first main surface 10a of the first light-transmitting substrate 10 is lower than the height H2 of the second light-transmitting region 34, which will be described later. When viewed in cross-section in an XZ cross-section, that is, a cross-section that includes the X direction (a predetermined direction) and is perpendicular to the first main surface 10a of the first light-transmitting substrate 10 and the first main surface 20a of the second light-transmitting substrate 20, the width D1 of the first light-transmitting region 32 is wider than the width D2 of the second light-transmitting region 34, which will be described later. The more specific configuration of the first light-transmitting region 32 will be described later. Note that the height H1 of the first light-transmitting region 32 from the first main surface 10a of the first light-transmitting substrate 10 will also be referred to as the height H1 of the first light-transmitting region 32.

[0024] In this embodiment, since the width D1 of the first light-transmitting region 32 is wide, the adhesion between the first light-transmitting substrate 10 and the first light-transmitting region 32 (light-transmitting layer) is improved. As a result, peeling of the light-transmitting region 30 (light-transmitting layer) from the first light-transmitting substrate 10 is suppressed, and the durability of the light ray direction control element 100 is improved.

[0025] The second light-transmitting region 34 has a rectangular parallelepiped shape that extends perpendicularly to the first main surface 10a of the first light-transmitting substrate 10 from the upper surface (+Z side surface) 32a of the first light-transmitting region 32 toward the second light-transmitting substrate 20. The second light-transmitting region 34 also extends in the Y direction. The second light-transmitting regions 34 are arranged in the X direction at intervals corresponding to the width D4 of the second light-absorbing region 44, which will be described later. The height H2 of the second light-transmitting region 34 from the upper surface 32a of the first light-transmitting region 32 is higher than the height H1 of the first light-transmitting region 32, and when viewed in cross-section in the XZ section, the width D2 of the second light-transmitting region 34 is narrower than the width D1 of the first light-transmitting region 32. The more specific configuration of the second light-transmitting region 34 will be described later. Note that the interval of the second light-transmitting regions 34 refers to the interval between the sides of adjacent second light-transmitting regions 34. Furthermore, the height H2 of the second light-transmitting region 34 from the upper surface 32a of the first light-transmitting region 32 is also referred to as the height H2 of the second light-transmitting region 34.

[0026] As shown in Figures 1 and 3, the light absorption region 40 of the light ray direction control element 100 is the region between adjacent light-transmitting regions 30. The light absorption region 40 has a first light absorption region 42 and a second light absorption region 44. The light absorption region 40 is formed by forming a light-transmitting region 30 on the first main surface 10a of the first light-transmitting substrate 10, as will be described later. The first light absorption region 42 is formed from adjacent first light-transmitting regions 32, and the second light absorption region 44 is formed from adjacent second light-transmitting regions 34.

[0027] The first light-absorbing region 42 is the region between adjacent first light-transmitting regions 32. Similar to the first light-transmitting regions 32, the first light-absorbing region 42 extends perpendicularly to the first main surface 10a of the first light-transmitting substrate 10 toward the second light-transmitting substrate 20. The second light-absorbing region 44 is the region between adjacent second light-transmitting regions 34, and extends perpendicularly to the first main surface 10a of the first light-transmitting substrate 10 toward the second light-transmitting substrate 20. Note that both the first light-absorbing region 42 and the second light-absorbing region 44 extend in the Y direction.

[0028] In this embodiment, the first light-absorbing region 42 is the region between adjacent first light-transmitting regions 32, so the height of the first light-absorbing region 42 from the first main surface 10a of the first light-transmitting substrate 10 is equal to the height H1 of the first light-transmitting region 32 from the first main surface 10a of the first light-transmitting substrate 10. Also, the second light-absorbing region 44 is the region between adjacent second light-transmitting regions 34, so the height of the second light-absorbing region 44 from the upper surface 42a of the first light-absorbing region 42 is equal to the height H2 of the second light-transmitting region 34 from the upper surface 32a of the first light-transmitting region 32. Furthermore, since the height H1 of the first light-transmitting region 32 is lower than the height H2 of the second light-transmitting region 34, the height H1 of the first light-absorbing region 42 is lower than the height H2 of the second light-absorbing region 44. Furthermore, the height of the first light-absorbing region 42 from the first main surface 10a of the first translucent substrate 10 is also referred to as the height H1 of the first light-absorbing region 42, and the height of the second light-absorbing region 44 from the upper surface 42a of the first light-absorbing region 42 is also referred to as the height H2 of the second light-absorbing region 44.

[0029] Furthermore, when viewed in cross-section along the XZ line, the width D1 of the first light-transmitting region 32 is narrower than the width D2 of the second light-transmitting region 34. Therefore, when viewed in cross-section along the XZ line, the width D3 of the first light-absorbing region 42 is narrower than the width D4 of the second light-absorbing region 44. The more specific configurations of the first light-absorbing region 42 and the second light-absorbing region 44 will be described later.

[0030] The translucent dispersion medium 52 of the light ray direction control element 100 is enclosed in the light absorption region 40. The translucent dispersion medium 52 transmits visible light. The translucent dispersion medium 52 disperses the electrophoretic particles 54.

[0031] The electrophoretic particles 54 of the light direction control element 100 are dispersed in a translucent dispersion medium 52 and absorb visible light. The electrophoretic particles 54 are positively or negatively charged, and their dispersion state in the translucent dispersion medium 52 changes depending on the voltage applied by the first translucent electrode 12 and the second translucent electrode 22. The electrophoretic particles 54 are, for example, charged carbon black particles. In this embodiment, it is assumed that the electrophoretic particles 54 are negatively charged.

[0032] The translucent dispersion medium 52 and the electrophoretic particles 54 dispersed in the translucent dispersion medium 52 are enclosed in the light-absorbing region 40. Therefore, the light-absorbing region 40 (first light-absorbing region 42 and second light-absorbing region 44) functions as an electrophoretic element together with the first translucent electrode 12 and the second translucent electrode 22. By controlling the potential V1 of the first translucent electrode 12 and the potential V2 of the second translucent electrode 22, the dispersion state of the electrophoretic particles 54 can be changed, and the light-absorbing region 40 can be made to function as a light-absorbing layer corresponding to the dispersion state of the electrophoretic particles 54.

[0033] Here, we will explain the operation of the ray direction control element 100. Here, we will explain the operation of the ray direction control element 100 assuming that a surface light source (uniformly diffuse surface light source) 700, which has a constant brightness regardless of the viewing direction, is placed on the first translucent substrate 10 side of the ray direction control element 100. The ray direction control element 100 controls the angular distribution of light 710 incident from the -Z direction and emits it in the +Z direction.

[0034] (Narrow field of view mode) When the potential V1 of the first transparent electrode 12 and the potential V2 of the second transparent electrode 22 are equal, and no voltage is applied to the electrophoretic particles 54, the electrophoretic particles 54 are uniformly dispersed throughout the light-absorbing region 40, and the light-absorbing region 40 (the first light-absorbing region 42 and the second light-absorbing region 44) functions as a light-absorbing layer throughout. Hereafter, this state will be referred to as the narrow-field mode.

[0035] When viewed in cross-section in the XZ plane, the first light absorption region 42 and the second light absorption region 44 are perpendicular to the first main surface 10a of the first translucent substrate 10. Therefore, in the narrow field of view mode, as shown in Figure 4, of the light 710 incident from the surface light source 700, light other than that near the +Z direction is absorbed by the first light absorption region 42 and the second light absorption region 44. Also, in the XZ plane, of the light 710 incident from the surface light source 700, light near the +Z direction is emitted from the ray direction control element 100. Therefore, if the +X direction is 0°, the +Z direction is 90°, and the -X direction is 180°, in a plane parallel to the XZ plane, the light emitted from the ray direction control element 100 in the narrow field of view mode has a narrow angular distribution near 90° (+Z direction), as shown in Figure 5.

[0036] In a plane parallel to the YZ plane that includes the first light-transmitting region 32 and the second light-transmitting region 34, the first light-transmitting region 32 and the second light-transmitting region 34 extend in the Y direction, so the light emitted from the ray direction control element 100 in the narrow field of view mode has a uniform angular distribution. In other planes parallel to the YZ plane, the first light-absorbing region 42 and the second light-absorbing region 44 extend in the Y direction, so the light 710 incident from the surface light source 700 is absorbed by the first light-absorbing region 42 and the second light-absorbing region 44. Note that a plane parallel to the YZ plane includes the YZ plane.

[0037] As described above, in the narrow field of view mode, the light emitted from the ray direction control element 100 has a narrow angular distribution near 90° (+Z direction) in a plane parallel to the XZ plane, and a uniform angular distribution in a plane parallel to the YZ plane that includes the first light-transmitting region 32 and the second light-transmitting region 34. Therefore, in the narrow field of view mode, the ray direction control element 100 can limit the viewing angle of the display device 300 in the left-right direction (X direction) to near the front (+Z direction).

[0038] (First wide-field mode) When the potential V1 of the first transparent electrode 12 is made greater than the potential V2 of the second transparent electrode 22, and a predetermined first voltage is applied to the electrophoretic particles 54, the negatively charged electrophoretic particles 54 gather in the first light absorption region 42, and only the first light absorption region 42 functions as a light absorption layer. Hereinafter, this state will be referred to as the first wide-field mode.

[0039] In the first wide-field mode, only the first light absorption region 42 functions as a light absorption layer, and the height H1 of the first light absorption region 42 from the first main surface 10a of the first translucent substrate 10 is lower than the height H2 of the second light absorption region 44 from the upper surface 42a of the first light absorption region 42. Therefore, when viewed in cross-section in the XZ plane, as shown in Figure 6, only a portion of the incident light 710 incident from the surface light source 700 that has a large angle with respect to the +Z direction is absorbed by the first light absorption region 42, and the other incident light is emitted from the ray direction control element 100. That is, in a plane parallel to the XZ plane, the light emitted from the ray direction control element 100 in the first wide-field mode has a wide angular distribution, as shown in Figure 5.

[0040] In a plane parallel to the YZ plane that includes the first light-transmitting region 32 and the second light-transmitting region 34, the first light-transmitting region 32 and the second light-transmitting region 34 extend in the Y direction, so the light emitted from the ray direction control element 100 in the narrow field mode has a uniform angular distribution. In other planes parallel to the YZ plane, the first light-absorbing region 42 extends in the Y direction, so the light 710 incident from the surface light source 700 is absorbed by the first light-absorbing region 42.

[0041] As described above, in the first wide-view mode, the light emitted from the ray direction control element 100 has a wide angular distribution in a plane parallel to the XZ plane and a uniform angular distribution in a plane parallel to the YZ plane that includes the first light-transmitting region 32 and the second light-transmitting region 34. Therefore, in the first wide-view mode, the ray direction control element 100 hardly restricts the viewing angle of the display device 300. The first wide-view mode refers to a state in which the angular distribution of the emitted light is wide.

[0042] The more specific configurations of the first light-transmitting region 32, the second light-transmitting region 34, the first light-absorbing region 42, and the second light-absorbing region 44 will now be described. As an example, the light-transmitting region 30 is formed with a height H1 of 25 μm for the first light-transmitting region 32, a width D1 of 45 μm for the first light-transmitting region 32, a height H2 of 120 μm for the second light-transmitting region 34, and a width D2 of 40 μm for the second light-transmitting region 34. The light-absorbing region 40 is formed with a height H1 of 25 μm for the first light-absorbing region 42, a width D3 (spacing between the first light-transmitting regions 32) of the first light-absorbing region 42, and a width D4 (spacing between the second light-transmitting regions 34) of the second light-absorbing region 44, which is 10 μm. The height H of the light-transmitting region 30 and the light-absorbing region 40 from the first main surface 10a of the first translucent substrate 10 is 145 μm.

[0043] The above light absorption region 40 is filled with a translucent dispersion medium 52 containing, for example, 4% by weight of electrophoretic particles 54 with an average particle size of 120 nm. Specifically, the particle density of the electrophoretic particles 54 is 0.5 g / cm³. 3 The maximum packing density of the electrophoretic particles 54 in the light absorption region 40 is set to 71.6% (74% in the most densely packed state), and the solvent density of the light-transmitting dispersion medium 52 is set to 0.75 g / cm³. 3 If the length (depth) in the Y direction of the light-transmitting region 30 and the light-absorbing region 40 is Lμm, then, as shown in equation (1) below, the electrophoretic particles 54 can be packed into 21.8μm of the height H1 (25μm) of the first light-absorbing region 42.

[0044]

number

[0045] When the first wide-field mode light direction control element 100, having the above configuration, is viewed from the +Z direction in a plan view as shown in Figure 7, the aperture ratio of the first wide-field mode light direction control element 100 is 90% ((45 / 50) × 100). On the other hand, when the light absorption region 40 is formed only by the second light absorption region 44 (hereinafter referred to as the comparative example), the aperture ratio of the wide-field mode light direction control element is 80% ((40 / 50) × 100). Note that in Figure 7, the first translucent substrate 10, the second translucent substrate 20, etc., are omitted for ease of understanding.

[0046] In this embodiment, the height H1 of the first light-transmitting region 32 that forms the first light-absorbing region 42 where electrophoretic particles 54 gather in the first wide-field mode is lower than the height H2 of the second light-transmitting region 34, and the aspect ratio of the first light-transmitting region 32 is small, so the spacing of the first light-transmitting regions 32 (i.e., the width D3 of the first light-absorbing region 42) can be easily narrowed. Since the width D1 of the first light-transmitting region 32 is wider than the width D2 of the second light-transmitting region 34, the width D3 of the first light-absorbing region 42 where electrophoretic particles 54 gather in the first wide-field mode becomes narrower than the width D4 of the second light-absorbing region 44, and as in the example above, the aperture ratio of the light-direction control element 100 in the first wide-field mode can be increased. Since the aperture ratio in the first wide-field mode is high, the transmittance of the light-direction control element 100 in the first wide-field mode can be increased, as shown in Figure 5.

[0047] Next, a method for manufacturing the light ray direction control element 100 will be described. Figure 8 is a flowchart of the method for manufacturing the light ray direction control element 100. The method for manufacturing the light ray direction control element 100 includes the steps of: preparing a mold 400 (step S100); filling the mold 400 with a light-transmitting resin 450 (step S102); pressing the first main surface 10a of the first light-transmitting substrate 10 against the light-transmitting resin 450 exposed from between the second column portions 424 (step S104); curing the light-transmitting resin 450 (step S106); and releasing the mold 400 from the cured light-transmitting resin 450 to form a plurality of light-transmitting layers 60 on the first main surface 10a of the first light-transmitting substrate 10 (step S108).

[0048] The method for manufacturing the light ray direction control element 100 further includes the steps of pressing a second translucent substrate 20 onto a plurality of translucent layers 60 (step S110) and filling the spaces between the translucent layers 60 with a translucent dispersion medium 52 in which electrophoretic particles 54 are dispersed (step S112).

[0049] In step S100, a mold 400 is prepared using known photolithography techniques to form a light-transmitting region 30 on the first main surface 10a of the first translucent substrate 10. As shown in Figure 9, the mold 400 comprises a mold substrate 410 and columnar portions 420. The mold substrate 410 is, for example, a silicon substrate. The columnar portions 420 are formed on the first main surface 410a of the mold substrate 410 from a chemically amplified photoresist: SU-8 (trade name, Nippon Kayaku Co., Ltd.) using known photolithography techniques. The shape of the columnar portions 420 corresponds to the light-absorbing region 40 of the light-direction control element 100. The shape of the space between adjacent columnar portions 420 corresponds to the shape of the light-transmitting region 30 of the light-direction control element 100.

[0050] The column portion 420 has a first column portion 422 and a second column portion 424. The first column portion 422 is provided perpendicular to the first main surface 410a of the mold substrate 410 and has a rectangular parallelepiped shape. The first column portions 422 are arranged in the X direction such that the spacing W21 between adjacent first column portions 422a (the +X side surface and the -X side surface) is equal to the width D2 of the second light-transmitting region 34 of the light ray direction control element 100, and they extend in the Z and Y directions. The height H21 of the first column portion 422 from the first main surface 410a of the mold substrate 410 is equal to the height H2 of the second light-absorbing region 44 and the second light-transmitting region 34. Also, when viewed in cross-section in the XZ section, the width D41 of the first column portion 422 is equal to the width D4 of the second light-absorbing region 44. The shape of the first column portion 422 corresponds to the shape of the second light absorption region 44 of the light ray direction control element 100, and the shape of the space 432 between adjacent first column portions 422 corresponds to the shape of the second light-transmitting region 34 of the light ray direction control element 100.

[0051] The second column portion 424 is provided on the upper surface (+Z side surface) 422b of the first column portion 422, perpendicular to the first main surface 410a, and has a rectangular parallelepiped shape. The second column portions 424 are arranged in the X direction, with the spacing W11 between adjacent second column portions 424a equal to the width D1 of the first light-transmitting region 32 of the light ray direction control element 100, and extend in the Z and Y directions. The height H11 of the second column portion 424 from the upper surface 422b of the first column portion 422 is equal to the height H1 of the first light-absorbing region 42 and the first light-transmitting region 32. Also, when viewed in cross-section in the XZ section, the width D31 of the second column portion 424 is equal to the width D3 of the first light-absorbing region 42. The shape of the second column portion 424 corresponds to the shape of the first light absorption region 42 of the light ray direction control element 100, and the shape of the space 434 between adjacent second column portions 424 corresponds to the shape of the first light-transmitting region 32 of the light ray direction control element 100.

[0052] In this embodiment, the height H21 of the first column portion 422 is equal to the height H2 of the second light-absorbing region 44 and the second light-transmitting region 34, and the height H11 of the second column portion 424 is equal to the height H1 of the first light-absorbing region 42 and the first light-transmitting region 32. Since the height H1 of the first light-absorbing region 42 and the first light-transmitting region 32 is lower than the height H2 of the second light-absorbing region 44 and the second light-transmitting region 34, the height H11 of the second column portion 424 (i.e., the height of the space 434 between adjacent second column portions 424) is lower than the height H21 of the first column portion 422 (i.e., the height of the space 432 between adjacent first column portions 422).

[0053] Furthermore, the spacing W21 of the first column sections 422 is equal to the width D2 of the second light-transmitting region 34, and the spacing W11 of the second column sections 424 is equal to the width D1 of the first light-transmitting region 32. Since the width D1 of the first light-transmitting region 32 is wider than the width D2 of the second light-transmitting region 34, the spacing W11 of the second column sections 424 (i.e., the width of the space 434 between adjacent second column sections 424) is wider than the spacing W21 of the first column sections 422 (i.e., the width of the space 432 between adjacent first column sections 422).

[0054] In step S102, as shown in Figure 10, a translucent resin 450 is filled between the column portions 420 of the mold 400. The filled translucent resin 450 is degassed. The translucent resin 450 is, for example, a thermosetting silicone resin.

[0055] In step S104, as shown in Figure 11, the first main surface 10a of the first translucent substrate 10 is pressed against the second column portion 424 and the translucent resin 450 exposed between the second column portion 424.

[0056] In step S106, the translucent resin 450, which is pressed against the first main surface 10a of the first translucent substrate 10, is heated and cured.

[0057] In step S108, as shown in Figure 12, the mold 400 is released from the cured translucent resin 450 to form a translucent layer 60 on the first main surface 10a of the first translucent substrate 10. The translucent layer 60 is formed from a first translucent layer 62 having a shape corresponding to the space 434 between adjacent second column portions 424, and a second translucent layer 64 having a shape corresponding to the space 432 between adjacent first column portions 422. The shape of the space 434 between adjacent second column portions 424 corresponds to the shape of the first translucent region 32 of the light ray direction control element 100, and the space 432 between adjacent first column portions 422 corresponds to the shape of the second translucent region 34 of the light ray direction control element 100. Therefore, in this step, a translucent layer 60 corresponding to the translucent region 30 of the light ray direction control element 100 is formed on the first main surface 10a of the first translucent substrate 10.

[0058] In step S110, as shown in Figure 13, the first main surface 20a of the second translucent substrate 20 is placed opposite the first main surface 10a of the first translucent substrate 10, and the second translucent substrate 20 is pressed onto the translucent layer 60.

[0059] In step S112, a translucent dispersion medium 52 containing electrophoretic particles 54 is filled between the translucent layers 60. This forms light-absorbing regions 40 (a first light-absorbing region 42 and a second light-absorbing region 44). The light-absorbing regions 40 are sealed with an adhesive.

[0060] As described above, the light ray direction control element 100 can be manufactured. In this embodiment, since the portion corresponding to the first light-transmitting region 32, which is arranged at a narrow interval (width D3 of the first light-absorbing region 42), is formed from the second column portion 424 of the mold 400, which is formed at a wide interval W11 (first light-transmitting layer 62), the light ray direction control element 100 can be easily manufactured.

[0061] As described above, the height H1 of the first light-transmitting region 32 forming the first light-absorbing region 42 is lower than the height H2 of the second light-transmitting region 34, and the width D1 of the first light-transmitting region 32 is wider than the width D2 of the second light-transmitting region 34. Therefore, the width D3 of the first light-absorbing region 42 where electrophoretic particles 54 gather in the first wide-field mode (a state in which the angular distribution of emitted light is wide) can be narrowed, and the aperture ratio of the light-direction control element 100 in the first wide-field mode can be increased. Consequently, the transmittance of the light-direction control element 100 in the first wide-field mode can be increased. In addition, because the width D1 of the first light-transmitting region 32 is wide, the adhesion between the first light-transmitting substrate 10 and the first light-transmitting region 32 (light-transmitting layer) can be improved, and the durability of the light-direction control element 100 can be increased.

[0062] <Embodiment 2> In the first wide-field mode of Embodiment 1, only the first light absorption region 42 functions as a light absorption layer. When the angular distribution of the emitted light from the light direction control element 100 is wide, the first light absorption region 42 and a portion of the second light absorption region 44 may also function as a light absorption layer. Hereinafter, the state in which the first light absorption region 42 and a portion of the second light absorption region 44 function as a light absorption layer will be described as the second wide-field mode. The other configurations of this embodiment, excluding the regions that function as light absorption layers, are the same as in Embodiment 1.

[0063] In the second wide-field mode, a predetermined second voltage, lower than the predetermined first voltage in the first wide-field mode, is applied to the electrophoretic particles 54. As a result, as shown in Figure 14, the electrophoretic particles 54 gather on the first translucent substrate 10 side, and the region 46 on the first light absorption region 42 side of the second light absorption region 44 functions as a light absorption layer.

[0064] In the second wide-field mode, the electrophoretic particles 54 also accumulate in the first light-absorbing region 42 located on the first translucent substrate 10 side, so the optical density (OD (Optical Density) value) of region 46 of the second light-absorbing region 44 is low. As a result, some of the light 710 incident on region 46 of the second light-absorbing region 44 passes through region 46 of the second light-absorbing region 44 and is emitted from the light direction control element 100. Therefore, in the second wide-field mode, similar to the first wide-field mode, the light direction control element 100 hardly restricts the viewing angle of the display device 300. Also, since some of the light 710 incident on region 46 of the second light-absorbing region 44 is emitted from the light direction control element 100, the transmittance of the light direction control element 100 in the second wide-field mode is higher than that of the comparative example in which the light-absorbing region 40 is formed only by the second light-absorbing region 44, as shown in Figure 15.

[0065] As described above, by applying a predetermined second voltage lower than a predetermined first voltage to the electrophoretic particles 54, the electrophoretic particles 54 are concentrated on the first translucent substrate 10 side, and even in the second wide-field mode (a state in which the angular distribution of emitted light is wide), in which the first light absorption region 42 and a part of the second light absorption region 44 (region 46) function as a light absorption layer, the transmittance of the ray direction control element 100 can be increased.

[0066] <Embodiment 3> In Embodiment 1 and Embodiment 2, the second light-transmitting region 34 of the light ray direction control element 100 has a rectangular parallelepiped shape, and when viewed in cross-section in the XZ plane, the second light-transmitting region 34 has a rectangular shape. When viewed in cross-section in the XZ plane, the second light-transmitting region 34 may have other shapes.

[0067] For example, as shown in Figure 16, when viewed in cross-section in the XZ plane, the second light-transmitting region 34 may have a trapezoidal shape (tapered shape). In this embodiment, the second light-transmitting region 34 has a trapezoidal shape in which the width D2b on the -Z side is wider than the width D2a on the +Z side. For example, the width D2b is 40 μm and the width D2a is 36 μm to 30 μm. The other dimensions of the light-transmitting region 30 are the same as in the example of Embodiment 1.

[0068] In this embodiment, since the width D2b on the -Z side of the second light-transmitting region 34 is wider than the width D2a on the +Z side of the second light-transmitting region 34, the width of the second light-absorbing region 44 narrows towards the first light-absorbing region 42, and the electrophoretic particles 54 can be easily collected in the first light-absorbing region 42 located on the -Z side.

[0069] <Embodiment 4> In Embodiment 1 and Embodiment 2, the first light-transmitting region 32 of the light ray direction control element 100 has a rectangular parallelepiped shape, and when viewed in cross-section in the XZ plane, the first light-transmitting region 32 has a rectangular shape. When viewed in cross-section in the XZ plane, the first light-transmitting region 32 may have other shapes.

[0070] For example, as shown in Figure 17, when viewed in cross-section in the XZ plane, the first light-transmitting region 32 may have a trapezoidal shape (tapered shape). In this embodiment, the first light-transmitting region 32 has a trapezoidal shape in which the width D1b on the -Z side is wider than the width D1a on the +Z side. For example, the width D1a is 45 μm and the width D1b is 47 μm. Also, for example, the width D3a on the +Z side of the first light-absorbing region 42 is 5 μm and the width D3b on the -Z side of the first light-absorbing region 42 is 3 μm. The other dimensions of the light-transmitting region 30 are the same as in the example of Embodiment 1.

[0071] In this embodiment, since the width D1b on the -Z side of the first light-transmitting region 32 is wider than the width D1a on the +Z side of the first light-transmitting region 32, the electrophoretic particles 54 can be easily collected in the first light-absorbing region 42.

[0072] <Embodiment 5> In one example of Embodiment 1, the ratio of the height H1 (25 μm) of the first light-transmitting region 32 to the height H2 (120 μm) of the second light-transmitting region 34 is 1:4.8. In the light ray direction control elements 100 of Embodiments 1 to 4, it is preferable that the ratio of the height H1 of the first light-transmitting region 32 to the height H2 of the second light-transmitting region 34 is 1:2.6 or higher.

[0073] For example, when the ray direction control element 100 of Embodiment 1 is viewed in cross-section in the XZ region, the maximum emission angle θ1 of light emitted from the ray direction control element 100 with respect to the +Z direction is given by Figure 18 and the following equation (2), neglecting the refraction of light in the first translucent substrate 10 and the second translucent substrate 20. Here, n is the refractive index of the translucent region 30, and θ2 is the angle of light incident on the ray direction control element 100 with respect to the +Z direction.

[0074]

number

[0075] Figure 19 shows the relationship between the height H2 of the second translucent region 34, obtained from equation (2), and the maximum emission angle θ1, when the height H1 of the first translucent region 32 is 25 μm, the width D1 of the first translucent region 32 is 45 μm, and the width D2 of the second translucent region 34 is 40 μm, similar to an example of Embodiment 1. As shown in Figure 19, when the refractive index n of the translucent region 30 is 1.5 and the height H2 of the second translucent region 34 is 65 μm or more (i.e., the ratio of the height H1 of the first translucent region 32 to the height H2 of the second translucent region 34 is 1:2.6), the maximum emission angle θ1 can be made 40° or less. Therefore, when the refractive index n of the translucent region 30 is 1.5 and the ratio of the height H1 of the first translucent region 32 to the height H2 of the second translucent region 34 is 1:2.6 or less, the left-right viewing angle of the display device 300 can be made 80° or less.

[0076] <Embodiment 6> In Embodiment 1, the ray direction control element 100 is manufactured using a mold. The ray direction control element 100 may also be manufactured using photolithography technology.

[0077] Figure 20 is a flowchart showing the manufacturing method of the light ray direction control element 100 of this embodiment. The manufacturing method of the light ray direction control element 100 of this embodiment includes the steps of: forming a light-shielding layer 502 at a predetermined interval W1 on the first main surface 10a of the first light-transmitting substrate 10 (step S200); laminating a first layer 504 formed from a photosensitive light-transmitting material with a predetermined first thickness D51 (step S202); exposing the first layer 504 from the side of the first light-transmitting substrate 10 (step S204); and laminating a second layer 506 formed from a photosensitive light-transmitting material on the exposed first layer 504 with a predetermined second thickness D52 that is thicker than the predetermined first thickness D51 (step S206).

[0078] The manufacturing method for the light direction control element 100 of this embodiment further includes the steps of: exposing a region 506a located between the light-shielding layer 502 of the second layer 506 from the side of the second layer 506 with a width D22 narrower than a predetermined spacing W1 of the light-shielding layer 502 (step S208); developing the exposed first layer 504 and the exposed second layer 506 to form a plurality of light-transmitting layers 60 on the first main surface 10a of the first light-transmitting substrate 10 (step S210); pressing the second light-transmitting substrate 20 onto the plurality of light-transmitting layers 60 (step S212); and filling the spaces between the light-transmitting layers 60 with a light-transmitting dispersion medium 52 in which electrophoretic particles 54 are dispersed (step S214).

[0079] In step S200, as shown in Figure 21, a plurality of light-shielding layers 502 are formed on the first main surface 10a of the first translucent substrate 10, aligned in the X direction. The light-shielding layers 502 block the light that exposes the translucent material forming the first layer 504 and the second layer 506. The light-shielding layers 502 are formed from chromium, aluminum, or the like. When viewed in cross-section in the XZ section, the light-shielding layers 502 are formed at predetermined intervals W1 and have a width D32. The predetermined interval W1 is equal to the width D1 of the first translucent region 32 of the light ray direction control element 100. The width D32 is equal to the width D3 of the first light absorption region 42, i.e., the interval of the first translucent region 32. The predetermined interval W1 refers to the distance between the sides of adjacent light-shielding layers 502.

[0080] In step S202, a first layer 504 formed from a light-transmitting material is laminated on the first main surface 10a of the first light-transmitting substrate 10 with a predetermined first thickness D51. The light-transmitting material is photosensitive. Furthermore, as shown in Figure 22, the first layer 504 is formed on the first main surface 10a of the first light-transmitting substrate 10, covering the light-shielding layer 502. The predetermined first thickness D51 is equal to the height H1 of the first light-transmitting region 32 and the first light-absorbing region 42. The photosensitive light-transmitting material is, for example, SU-8.

[0081] In step S204, first, the laminated first layer 504 is pre-baked (95°C, 3 hours) to remove the solvent contained in the laminated first layer 504. Next, as shown in Figure 23, the first layer 504 is exposed from the first translucent substrate 10 side without using a mask. The thickness D51 of the first layer 504 is equal to the height H1 of the first translucent region 32 and the first light-absorbing region 42, and a light-shielding layer 502 having a width D32 equal to the width D3 of the first light-absorbing region 42 is formed at intervals W1 equal to the width D1 of the first translucent region 32 of the light-direction control element 100. Therefore, the region corresponding to the first translucent region 32 of the light-direction control element 100 is exposed.

[0082] In step S204, after exposing the first layer 504, a Post Exposure Bake (PEB) process is performed (95°C, 25 minutes).

[0083] In step S206, as shown in Figure 24, a second layer 506 formed from a translucent material is laminated on the exposed first layer 504 with a predetermined second thickness D52. The translucent material forming the second layer 506 is photosensitive. The translucent material forming the second layer 506 and the translucent material forming the first layer 504 may be the same or different. The predetermined second thickness D52 is equal to the height H2 of the second light-transmitting region 34 and the second light-absorbing region 44, and is thicker than the predetermined first thickness D51.

[0084] In step S208, first, the stacked second layer 506 is pre-baked (95°C, 30 minutes). Next, as shown in Figure 25, using a mask M, the region 506a located between the light-shielding layers 502 of the second layer 506 when viewed from above is exposed with a width D22. The width D22 is equal to the width D2 of the second light-transmitting region 34 and is narrower than the predetermined spacing W1 of the light-shielding layers 502. The thickness D52 of the second layer 506 is equal to the height H2 of the second light-transmitting region 34 and the second light-absorbing region 44, and the width D22 is equal to the width D2 of the second light-transmitting region 34, so the region corresponding to the second light-transmitting region 34 of the light-ray direction control element 100 is exposed.

[0085] In step S208, after exposing the second layer 506, PEB treatment is performed (95°C, 25 minutes).

[0086] In step S210, the exposed first layer 504 and the exposed second layer 506 are developed with a developer. After development, the first layer 504 and the second layer 506 are rinsed with a rinsing solution and post-baked (150°C, 30 minutes). As a result, as shown in Figure 26, multiple light-transmitting layers 60 are formed on the first main surface 10a of the first light-transmitting substrate 10.

[0087] In this embodiment, in step S204, the region corresponding to the first light-transmitting region 32 of the first layer 504 is exposed, and in step S208, the region corresponding to the second light-transmitting region 34 of the second layer 506 is exposed. Therefore, in this step, a light-transmitting layer 60 corresponding to the light-transmitting region 30 of the light-ray direction control element 100 is formed on the first main surface 10a of the first light-transmitting substrate 10.

[0088] Steps S212 and S214 in this embodiment are the same as steps S110 and S112 in Embodiment 1.

[0089] As described above, the light ray direction control element 100 can be manufactured. In step S204 of this embodiment, the region of the first layer 504 corresponding to the first light-transmitting region 32 is exposed from the side of the first light-transmitting substrate 10. As a result, the first layer 504 is exposed through a light-shielding layer 502 having a width D32 equal to the spacing of the first light-transmitting regions 32 (width D3 of the first light-absorbing region 42), so that the portion corresponding to the first light-transmitting regions 32 arranged at narrow intervals (width D3 of the first light-absorbing region 42) can be easily formed, and the light ray direction control element 100 can be easily manufactured. In this embodiment, the light-shielding layer 502 is located on the first main surface 10a of the first light-transmitting substrate 10. Since the light-shielding layer 502 is located within the light-absorbing region 40, the light-shielding layer 502 does not affect the characteristics of the light ray direction control element 100.

[0090] <Variation> While embodiments have been described above, this disclosure can be modified in various ways without departing from its essence.

[0091] For example, the first translucent substrate 10 and the second translucent substrate 20 may be formed from a translucent resin. Also, the electrophoretic particles 54 may be positively charged.

[0092] In this embodiment, the mold 400 is manufactured using a known photolithography technique. The mold 400 may also be manufactured by cutting a metal (e.g., silicon). Alternatively, the mold 400 may be a plated nickel (Ni) mold, a copper (Cu) mold, or the like.

[0093] In this embodiment, the columnar portion 420 is formed from a chemically amplified photoresist: SU-8. The columnar portion 420 may be formed from other resists. For example, the columnar portion 420 may be formed from a negative-type resist: KMPR (trade name, Nippon Kayaku Co., Ltd.). Alternatively, the columnar portion 420 may be formed using a dry film resist.

[0094] In this embodiment, a thermosetting silicone resin is used as the translucent resin 450. The translucent resin 450 may also be a thermosetting epoxy resin, a thermosetting acrylic resin, or the like.

[0095] Furthermore, the translucent resin 450 may be a UV (Ultra Violet) curing resin (silicone resin, epoxy resin, acrylic resin, etc.). When a UV curing resin is used as the translucent resin 450, the translucent resin 450 is cured by irradiating it with UV light from either the first translucent substrate 10 side or the second translucent substrate 20 side (step S106).

[0096] In this embodiment, the light 710 incident on the light direction control element 100 is incident on the first translucent substrate 10 side (-Z side). As shown in Figure 27, the light 710 may also be incident on the light direction control element 100 from the second translucent substrate 20 side (+Z side). In this case, the light direction control element 100 controls the angular distribution of the light 710 incident from the +Z direction and emits it in the -Z direction.

[0097] In one example of Embodiment 1, the electrophoretic particles 54 can be packed into 21.8 μm of the height H1 (25 μm) of the first light absorption region 42. In the first wide-angle mode, the electrophoretic particles 54 only need to be packed into a height less than or equal to the height H1 of the first light absorption region 42.

[0098] In this embodiment, the ray direction control element 100 operates in a first wide-field mode, a second wide-field mode, and a narrow-field mode. The ray direction control element 100 may also operate in a first wide-field mode and a narrow-field mode. Furthermore, the ray direction control element 100 may also operate in a second wide-field mode and a narrow-field mode.

[0099] When the light direction control element 100 operates in the second wide-field mode and the narrow-field mode, the electrophoretic particles 54 dispersed in the translucent dispersion medium 52 may have a concentration or volume that fills the regions 46 of the first light absorption region 42 and the second light absorption region 44 when a voltage of a predetermined second voltage or higher is applied.

[0100] In Embodiment 3, when viewed in an XZ cross-section, the second light-transmitting region 34 has a trapezoidal shape. In Embodiment 4, the first light-transmitting region 32 has a trapezoidal shape. When viewed in an XZ cross-section, both the first light-transmitting region 32 and the second light-transmitting region 34 may have a trapezoidal shape.

[0101] In Embodiments 1 to 4, the side surface of the first light-transmitting region 32 is planar, but the side surface of the first light-transmitting region 32 may be curved, as shown in Figure 28. For example, the width D1b on the -Z side of the first light-transmitting region 32 is 47 μm, and the width D3b on the -Z side of the first light-absorbing region 42 is 3 μm. Furthermore, the corner 32b of the first light-transmitting region 32 may be curved, as shown in Figure 29.

[0102] In the trapezoidal first light-transmitting region 32, as shown in Figure 30, the width D1b on the -Z side is wider than the width D1a on the +Z side, and the width D1a on the +Z side of the first light-transmitting region 32 may be equal to the width D2 of the second light-transmitting region 34 (width on the -Z side). Thus, the width D1 of the first light-transmitting region 32 continuously widens toward the first light-transmitting substrate 10 from the width D2 of the second light-transmitting region 34 (width on the -Z side) to the width D1b on the -Z side. Therefore, as shown in Figure 31, in the first wide-field mode, it is possible to suppress the retention of some of the electrophoretic particles 54 on the step portion 38 (upper surface 32a of the first light-transmitting region 32) between the first light-transmitting region 32 and the second light-transmitting region 34. By suppressing the retention of electrophoretic particles 54, the transmittance of the light direction control element 100 in the first wide-field mode can be further increased.

[0103] It is sufficient that there is no step portion 38 between the first light-transmitting region 32 and the second light-transmitting region 34. For example, in the modified example described above (Figure 30), the side surface of the first light-transmitting region 32 is planar, but the side surface of the first light-transmitting region 32 may be curved, as shown in Figures 32 and 33. In this modified example as well, the width D1b on the -Z side is wider than the width D1a on the +Z side, and the width D1a on the +Z side of the first light-transmitting region 32 is equal to the width D2 (-Z side width) of the second light-transmitting region 34. The width D1 of the first light-transmitting region 32 widens continuously toward the first light-transmitting substrate 10 from the width D2 (-Z side width) of the second light-transmitting region 34 to the width D1b on the -Z side. In this modified example as well, similar to the modified example described above, the step portion 38 between the first light-transmitting region 32 and the second light-transmitting region 34 can be eliminated, and the residue of electrophoretic particles 54 can be suppressed. By suppressing the residue of electrophoretic particles 54, the transmittance of the ray direction control element 100 in the first wide-field mode can be further increased.

[0104] Furthermore, as shown in Figure 34, the step portion 38 between the first light-transmitting region 32 and the second light-transmitting region 34 may be eliminated by cutting out the corner portion 32b of the first light-transmitting region 32 in a curved shape. In this modified example as well, the width D1 of the first light-transmitting region 32 continuously widens toward the first light-transmitting substrate 10 from the width D2 of the second light-transmitting region 34 (width on the -Z side) to the width D1b on the -Z side. In this modified example as well, the residue of electrophoretic particles 54 can be suppressed. By suppressing the residue of electrophoretic particles 54, the transmittance of the ray direction control element 100 in the first wide-field mode can be further increased.

[0105] The display device 300 may consist of a light ray direction control element 100, a transmissive liquid crystal display panel 215, and a backlight 220, as shown in Figure 35. The backlight 220 is positioned on the opposite side of the display surface of the transmissive liquid crystal display panel 215 and supplies light to the transmissive liquid crystal display panel 215. The light ray direction control element 100 is positioned between the transmissive liquid crystal display panel 215 and the backlight 220 and controls the angular distribution of the light supplied from the backlight 220 to the transmissive liquid crystal display panel 215.

[0106] Furthermore, as shown in Figure 36, the ray direction control element 100 may be placed on the display surface of the transmissive liquid crystal display panel 215.

[0107] While preferred embodiments have been described above, this disclosure is not limited to any particular embodiment, and includes the invention described in the claims and its equivalents. [Explanation of symbols]

[0108] 10 First light-transmitting substrate, 10a First main surface, 12 First light-transmitting electrode, 20 Second light-transmitting substrate, 20a First main surface, 22 Second light-transmitting electrode, 30 Light-transmitting region, 32 First light-transmitting region, 32a Top surface, 32b Corner, 34 Second light-transmitting region, 38 Stepped portion, 40 Light-absorbing region, 42 First light-absorbing region, 42a Top surface, 44 Second light-absorbing region, 46 Region, 52 Light-transmitting dispersion medium, 54 Electrophoretic particles, 60 Light-transmitting layer, 62 First light-transmitting layer, 64 Second light-transmitting layer, 100 Light ray direction control element, 210 Display panel, 215 Transmissive liquid crystal display panel, 220 Backlight, 300 Display device, 400 Mold, 410 Molded substrate, 410a First main surface, 420 Column portion, 422 1st column, 422a side, 422b top, 424 2nd column, 424a side, 432,434 space, 450 translucent resin, 502 light shielding layer, 504 1st layer, 506 2nd layer, 506a area, 700 surface light source, 710 Light, D1,D1a,D1b,D2,D2a,D2b,D22,D3,D3a,D3b,D31,D32,D4,D41 width, D51,D52 thickness, H1,H2,H11,H21 height, W1,W11,W21 interval, n refractive index, M mask, θ1 maximum output angle, θ2 angle

Claims

1. a first translucent substrate having a first translucent electrode on a principal surface thereof; a second light-transmitting substrate facing the first light-transmitting substrate and having a second light-transmitting electrode on a main surface facing the main surface of the first light-transmitting substrate; a plurality of light-transmitting regions arranged in a predetermined direction and sandwiched between the first light-transmitting substrate and the second light-transmitting substrate; a plurality of light absorbing regions positioned between the light transmitting regions; a light-transmitting dispersion medium enclosed in the light-absorbing region; electrophoretic particles that absorb light, are dispersed in the light-transmitting dispersion medium, and whose dispersion state changes depending on an applied voltage; each of the light-transmitting regions includes a first light-transmitting region extending from the main surface of the first light-transmitting substrate toward the second light-transmitting substrate, perpendicular to the main surface of the first light-transmitting substrate; and a second light-transmitting region extending from an upper surface of the first light-transmitting region toward the second light-transmitting substrate, perpendicular to the main surface of the first light-transmitting substrate; each of the light absorbing regions has a first light absorbing region located between the first light transmitting regions and a second light absorbing region located between the second light transmitting regions; a height of the first light-transmitting region from the main surface of the first light-transmitting substrate is lower than a height of the second light-transmitting region from an upper surface of the first light-transmitting region; When viewed in a cross section that includes the predetermined direction and is perpendicular to the main surface of the first light-transmitting substrate, a width of the first light-transmitting region is wider than a width of the second light-transmitting region. Beam direction control element.

2. when a predetermined first voltage is applied between the first light-transmitting electrode and the second light-transmitting electrode, the electrophoretic particles gather within the first light-absorbing region; 10. The beam direction control element of claim 1.

3. when a predetermined second voltage is applied between the first light-transmitting electrode and the second light-transmitting electrode, the electrophoretic particles gather on the first light-transmitting substrate side; 10. The beam direction control element of claim 1.

4. a ratio of a height of the first light-transmitting region from the main surface of the first light-transmitting substrate to a height of the second light-transmitting region from the upper surface of the first light-transmitting region is 1:2.6 or more; 10. The beam direction control element of claim 1.

5. the width of the first light-transmitting region continuously increases from the width of the second light-transmitting region toward the first light-transmitting substrate; 10. The beam direction control element of claim 1.

6. A beam direction control element according to any one of claims 1 to 5; a display panel, the light direction control element is disposed on the display surface of the display panel; Display device.

7. A beam direction control element according to any one of claims 1 to 5; a transmissive liquid crystal display panel; a backlight disposed on the opposite side of the display surface of the transmissive liquid crystal display panel to supply light to the transmissive liquid crystal display panel; the light direction control element is disposed between the transmissive liquid crystal display panel and the backlight; Display device.

8. a step of preparing a mold having a mold substrate, a plurality of first pillar portions arranged on a main surface of the mold substrate perpendicular to the main surface and aligned in a predetermined direction, and a second pillar portion arranged on an upper surface of each of the plurality of first pillar portions perpendicular to the main surface of the mold substrate; filling the mold with a light-transmitting resin; a step of pressing a main surface of a first light-transmitting substrate having a first light-transmitting electrode on the main surface against the second columnar portions and the light-transmitting resin exposed between the second columnar portions; curing the light-transmitting resin pressed against the main surface of the first light-transmitting substrate; a step of releasing the mold from the cured light-transmitting resin and forming a plurality of light-transmitting layers on the main surface of the first light-transmitting substrate, the light-transmitting layers including first light-transmitting layers having shapes corresponding to the shapes of the spaces between adjacent second columnar portions and second light-transmitting layers having shapes corresponding to the shapes of the spaces between adjacent first columnar portions; a step of pressure-bonding a second light-transmitting substrate, which faces the first light-transmitting substrate and has a second light-transmitting electrode on a main surface facing the main surface of the first light-transmitting substrate, onto the plurality of light-transmitting layers; and filling a transparent dispersion medium between the light-transmitting layers, the transparent dispersion medium containing dispersed electrophoretic particles that absorb light and whose dispersion state changes depending on an applied voltage, The height of the space between the adjacent second pillar portions is lower than the height of the space between the adjacent first pillar portions, When viewed in a cross section that includes the predetermined direction and is perpendicular to the main surface of the mold substrate, the width of a space between adjacent second columnar portions is wider than the width of a space between adjacent first columnar portions. Method for manufacturing a beam direction control element.

9. forming a light-shielding layer at a predetermined interval on a main surface of a first light-transmitting substrate having a first light-transmitting electrode on the main surface; a step of laminating a first layer made of a light-sensitive light-transmitting material and covering the light-shielding layer on the main surface of the first light-transmitting substrate to a predetermined first thickness; exposing the first layer to light from the side of the first light-transmitting substrate; laminating a second layer made of a light-sensitive, light-transmitting material on the exposed first layer to a second predetermined thickness that is thicker than the first predetermined thickness; exposing a region of the second layer located between the light-shielding layers in a plan view from the second layer side to light with a width narrower than the predetermined interval between the light-shielding layers; developing the exposed first layer and the exposed second layer to form a plurality of light-transmitting layers on the major surface of the first light-transmitting substrate; a step of pressure-bonding a second light-transmitting substrate, which faces the first light-transmitting substrate and has a second light-transmitting electrode on a main surface facing the main surface of the first light-transmitting substrate, onto the plurality of light-transmitting layers; and filling a transparent dispersion medium between the light-transmitting layers, the transparent dispersion medium containing dispersed electrophoretic particles that absorb light and whose dispersion state changes depending on an applied voltage. Method for manufacturing a beam direction control element.

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