Stereoscopic image display device and optical sheet

Abstract

The present invention addresses the problem of providing a stereoscopic image display device having a high display contrast and an optical sheet capable of obtaining a high display contrast when used in a stereoscopic image display device. A self-luminous image display device includes a lens array, a directivity control layer, and a self-luminous image display element in this order, one surface of the lens array has a planar shape, the other surface has a curved surface shape, and the directivity control layer is disposed on the planar surface side of the lens array. The directivity control layer has the highest brightness in the normal direction of the other surface when light is irradiated from the one surface side.

Description

Technical Field

[0001] This invention relates to a stereoscopic image display device and an optical sheet for the stereoscopic image display device. Background Technology

[0002] A stereoscopic image display device is known, which displays stereoscopic images by combining lens arrays such as columnar lenses and microlens arrays on image display elements such as liquid crystal displays.

[0003] For example, Patent Document 1 describes a stereoscopic image display device (three-dimensional image display device) which includes: The display device includes a display panel capable of simultaneously displaying multiple images with parallax. Multiple display pixels that display multiple images with parallax are grouped together, and the display pixel group is arranged in a matrix. A cylindrical lens is disposed on the image light emission side of the display panel. Multiple unit lenses, approximately cylindrical or approximately elliptical cylindrical in shape, are arranged on the emission side surface, causing the image light of multiple images with parallax to be emitted in predetermined directions respectively; and A light control sheet is disposed between the cylindrical lens and the display panel, with the light-transmitting part and the light-absorbing part arranged alternately along the arrangement direction of the unit lens. Previous technical documents Patent documents

[0004] Patent Document 1: Japanese Patent Application Publication No. 2012-93631 Summary of the Invention The technical problem to be solved by the invention

[0005] A stereoscopic image display device using this lens array divides the image into multiple images corresponding to the parallax of the left and right eyeballs, arranges the divided images, and displays them. An observer views the image through the lens array, thereby reconstructing the image at the positions of the observer's left and right eyeballs and observing it as a stereoscopic image. That is, with a stereoscopic image display device using such a lens array and image display element, the observer can observe stereoscopic images with the naked eye without using special glasses such as glasses with polarizers.

[0006] However, the display contrast of conventional stereoscopic image display devices that allow the naked eye to observe stereoscopic images is insufficient and needs improvement.

[0007] The purpose of this invention is to solve the problems of the prior art and to provide a stereoscopic image display device with high display contrast and an optical sheet that can improve the display contrast when used in a stereoscopic image display device. means for solving technical problems

[0008] To achieve this objective, the present invention has the following structure. [1] A stereoscopic image display device, comprising, in sequence: A lens array, which arranges multiple lenses in a planar shape; Directional control layer; and Self-emissive image display element, One side of the lens array is planar, while the other side has a curved shape. A directional control layer is disposed on the planar side of the lens array. The directional control layer is selected from the group consisting of an anisotropic absorption layer of dichroic material, a diffraction element, a metasurface structure and a polarizer, and a phase difference layer and a polarizer. The directional control layer is the layer whose brightness is highest in the normal direction of the other surface of the directional control layer when light is shone from one surface side of the directional control layer. [2] According to the stereoscopic image display device described in [1], wherein, The directional control layer is an anisotropic absorption layer containing dichroic material, and the central axis of transmittance is parallel to the normal direction of the planar surface of the lens array. [3] According to the stereoscopic image display device described in [2], wherein, The anisotropic absorption layer contains a liquid crystal compound that is vertically oriented. [4] The stereoscopic image display device according to any one of [1] to [3], wherein, The lens array consists of cylindrical lenses. [5] According to the stereoscopic image display device described in [4], wherein, A polarizer is also present between the image display element and the orientation control layer. The transmission axis of the polarizer is orthogonal to the length direction of the lens that forms the cylindrical lens. [6] The stereoscopic image display device according to any one of [1] to [3], wherein, The lens array is a microlens array. [7] An optical sheet comprising: a lens array arranging a plurality of lenses in a planar configuration; and an anisotropic absorption layer comprising a dichroic material, wherein... One side of the lens array is planar, while the other side has a curved shape. An anisotropic absorption layer is disposed on the planar side of the lens array. The transmittance central axis of the anisotropic absorption layer is parallel to the normal direction of the planar surface of the lens array. [8] According to the optical sheet described in [7], wherein, The anisotropic absorption layer contains a liquid crystal compound that is vertically oriented. [9] The optical sheet according to [7] or [8], wherein, The lens array consists of cylindrical lenses.

[10] According to the optical sheet described in [9], wherein, A polarizer is also present on the side of the anisotropic absorption layer opposite to the lens array side. The transmission axis of the polarizer is orthogonal to the length direction of the lens that forms the cylindrical lens.

[11] The optical sheet according to [7] or [8], wherein, The lens array is a microlens array. Invention Effects

[0009] According to the present invention, a stereoscopic image display device with high display contrast and an optical sheet that can obtain high display contrast when used in a stereoscopic image display device are provided. Attached Figure Description

[0010] Figure 1 This is a diagram that conceptually illustrates an example of the stereoscopic image display device of the present invention. Figure 2 This is a diagram that conceptually represents an example of the light-emitting characteristics of a light-emitting element in an image display element. Figure 3 This is a diagram illustrating an example of the light-emitting characteristics of the light-emitting elements in an image display element. Figure 4 It is a graph representing the simulation results of the absorption characteristics of the anisotropic absorption layer. Figure 5 It is a graph showing the simulation results of the light quantity distribution after the light is transmitted through the anisotropic absorption layer. Figure 6 This is a diagram that conceptually illustrates another example of the stereoscopic image display device of the present invention. Figure 7 It is a graph showing the simulation results of the transmittance in the laminate of the anisotropic absorption layer and the polarizer. Figure 8 It is a graph showing the simulation results of the light quantity distribution of the stack of anisotropic absorption layer and polarizer transmitted through it. Detailed Implementation

[0011] The stereoscopic image display device and optical sheet of the present invention will be described in detail below. The following description is based on a representative embodiment of the present invention, but the present invention is not limited to this embodiment. In addition, in this specification, the numerical range indicated by “~” represents the range including the values ​​recorded before and after “~” as the lower limit and upper limit values. Furthermore, the figures shown below are conceptual diagrams used to illustrate the present invention. Therefore, the shape, size, thickness, and positional relationships of the components, such as their arrangement and spacing, may not necessarily correspond to the actual device in the figures.

[0012] Figure 1 The present invention is conceptually illustrated as an example of a stereoscopic image display device. Figure 1 The stereoscopic image display device 10 shown includes, in sequence, an image display element 12, an anisotropic absorption layer 14, and a microlens array 16. The anisotropic absorption layer 14 is the directional control layer in this invention. Furthermore, the microlens array 16 is the lens array in this invention.

[0013] In the stereoscopic image display device of the present invention, the lens array arranges (distributes) multiple lenses into a planar shape, wherein one planar surface and another curved surface are arranged. Furthermore, in the present invention, the planar surface is not limited to a perfectly flat surface, but also includes substantially flat surfaces such as those with unavoidable unevenness. In this invention, a curved surface of a lens array means that the surface does not include vertices where two straight lines intersect or edges where two planes intersect. Specifically, it means that the lenses constituting the lens array are lenses that do not include vertices like those of an axonocone lens or edges like those of a prism.

[0014] Furthermore, the anisotropic absorption layer 14 contains a dichroic material, and the central axis of the transmittance is parallel to the normal direction of the planar surface of the microlens array 16 (lens array). Furthermore, the normal direction is the direction orthogonal to the surface of the sheet-like material (layer, film, plate). And, a normal refers to a line orthogonal to the surface of the sheet-like material. That is, the combination of the anisotropic absorption layer 14 and the microlens array 16 (lens array) constitutes the optical sheet of the present invention. Therefore, Figure 1 The stereoscopic image display device 10 shown is a stereoscopic image display device of the present invention using the optical sheet of the present invention.

[0015] In the stereoscopic image display device of the present invention, in addition to the anisotropic absorption layer 14 shown in the figure example, a stack of diffraction elements, metasurface structures and polarizers, and phase difference layers and polarizers can also be used as the directional control layer. This will be described in detail later.

[0016] In the stereoscopic image display device 10 of the present invention, the image display element 12 is a self-emissive image display element. As long as the image display element 12 is a self-emissive image display element, it can utilize known image display elements (image display devices, displays). As an example of an image display element, LED (Light Emitting Diode) display elements, micro LED display elements, and organic EL (ElectroLuminescence) display elements (OLED (Organic Light Emitting Diode)) are preferably exemplified.

[0017] In the stereoscopic image display device 10 of the present invention, the image display element 12 is a conventional self-emissive image display element. In the stereoscopic image display device 10, similar to the image display element of a known stereoscopic image display device that can be observed by the naked eye using a lens array, the image display element 12 divides and arranges multiple images corresponding to the viewer's viewpoint according to the microlens array 16. In this respect, the same applies to the use of other lens arrays such as cylindrical lenses in the stereoscopic image display device of the present invention.

[0018] In the stereoscopic image display device 10 of the present invention, as long as the microlens array 16 is also a structure with one side being planar and the other side having a curved shape, it is possible to utilize the known microlens arrays used in various stereoscopic image display devices that use lens arrays to display stereoscopic images to the naked eye.

[0019] Furthermore, in the stereoscopic image display device of the present invention, the lens array is not limited to the microlens array 16. That is, in the stereoscopic image display device of the present invention, the lens array is a lens array in which multiple lenses are arranged in a planar shape. As long as one surface is planar and the other surface has the curved shape described above, various known lens arrays for stereoscopic image display devices that can be observed by the naked eye can be used. In addition to the microlens array 16 shown in the figure, other examples of such lens arrays include cylindrical lenses, compound eye lenses, and other structures in which a spherical or semi-cylindrical shape is configured as a convex structure.

[0020] Here, in the stereoscopic image display device 10 of the present invention, the microlens array 16, i.e., the lens array, is configured with its planar surface facing the anisotropic absorption layer 14, i.e., the directivity control layer. That is, the microlens array 16 is configured with its planar surface facing the image display element 12. In other words, the anisotropic absorption layer 14 is disposed on the planar side of the microlens array 16.

[0021] The stereoscopic image display device of the present invention comprises, in sequence, a lens array, a directional control layer and an image display element. Therefore, in the stereoscopic image display device 10 of the present invention, an anisotropic absorption layer 14 is provided between the image display element 12 and the microlens array 16. That is, in the stereoscopic image display device 10, the image displayed by the image display element 12 is transmitted through the anisotropic absorption layer 14 and incident into the microlens array 16, and is refracted by the microlens array 16 to be observed by the observer as a stereoscopic image.

[0022] Here, the anisotropic absorption layer 14 is the directional control layer in this invention, and is a layer containing dichroic material, with the transmittance central axis parallel to the normal direction of the planar surface of the microlens array 16 (lens array). Furthermore, in this invention, "parallel to the normal direction of the planar surface of the microlens array 16" includes not only being completely parallel to the normal direction of the planar surface, but also an angle range of ±5° relative to the normal direction of the planar surface. The same applies to descriptions such as the normal direction in the directional control layer and the parallelism of the main surfaces of components.

[0023] In this invention, a directivity control layer refers to a layer whose brightness is highest in the normal direction of the other surface of the directivity control layer when light is irradiated from one surface of the layer. Specifically, the directivity control layer is a layer in which the brightness of the light transmitted from the other surface of the layer is highest in the normal direction when light is irradiated from one surface of the layer in various directions by changing the polar angle and azimuth angle in various ways. In addition, in this invention, as described above, the normal direction includes not only the direction that is completely consistent with the normal of the main surface, i.e., the direction that is completely orthogonal to the main surface (orthogonal line), but also an angular range of ±5° relative to the normal of the main surface. That is, regarding the directionality control layer, light incident from the normal direction of the main surface is directly transmitted. In contrast, the directionality control layer absorbs light incident at an angle relative to the normal direction of the main surface, or changes the light path to be parallel to the normal direction of the main surface and emits light. In addition, the main surface refers to the largest surface of a sheet (film, plate, layer), which is usually the two surfaces in the thickness direction of the sheet.

[0024] As described above, the anisotropic absorption layer 14 is a directional control layer and contains a dichroic material, with its transmittance central axis parallel to the normal direction of the planar surface of the microlens array 16. In this invention, the transmittance center axis refers to the direction in which the transmittance is highest when the polar angle and azimuth angle are varied and measured from the surface of the layer in various directions. In the anisotropic absorption layer 14, where the central axis of transmittance is parallel to the normal direction of the planar surface of the microlens array 16, light incident from the normal direction of the planar surface of the microlens array 16 is directly transmitted, while light incident from the tilted direction relative to the normal is absorbed. Typically, in the stereoscopic image display device 10 of the present invention, the anisotropic absorption layer 14 is arranged with its main surface parallel to the planar surface of the microlens array 16. Therefore, in the stereoscopic image display device 10, the normal direction of the planar surface of the microlens array 16 is aligned with the normal direction of the main surface of the anisotropic absorption layer 14. In the following description, the normal direction of the planar surface of the microlens array 16 and the normal direction of the main surface of the anisotropic absorption layer 14 will also be referred to as the "normal direction".

[0025] That is, the stereoscopic image display device 10 sets the light of the image displayed by the self-emissive image display element 12 to travel in the normal direction (approximately normal direction) through the anisotropic absorption layer 14, and causes the light traveling in the normal direction to be incident on the microlens array 16 to display the stereoscopic image. In the stereoscopic image display device 10 of the present invention, which uses a microlens array 16 (lens array) to display stereoscopic images that can be viewed by the naked eye, an anisotropic absorption layer 14 (directivity control layer) is provided between the microlens array 16 and the image display element 12, thereby improving the display contrast of the stereoscopic image.

[0026] The stereoscopic image display device 10 shown in the figure uses a microlens array 16, which is a so-called light field display. This stereoscopic image display device uses a lens array, such as a microlens array, positioned between the image display element and the observer to reconfigure the image on the image display element according to the viewing angle, and the collection of images from each lens of the microlens array reconstructs the original image at the viewing point. If the image on the image display element is configured in such a way that the reconstructed image at the respective positions of the observer's left and right eyeballs reproduces the observer's left and right parallax, then the observer can experience a stereoscopic image display with the naked eye. The same applies to stereoscopic image display devices that use lens arrays such as cylindrical lenses.

[0027] As described above, the microlens array 16 can utilize a known microlens array for stereoscopic image display. Therefore, the shape of the microlens array (lens array) can be varied depending on the resolution, pixel structure, and image quality of the image display element used. For the sake of simplicity, an array of microlenses consisting of plano-convex lenses arranged with simple spherical surfaces will be used as an example in this description. However, the scope of this invention is not necessarily limited to these examples. For instance, plano-concave lenses may be used instead of plano-convex lenses. Furthermore, the lenses may not be spherical but aspherical in shape.

[0028] When using a plano-convex lens with the planar side facing the image display element side, the light rays incident on the lens from the image display element side are preferably parallel to the optical axis of the lens. However, it is known that the light distribution of each pixel constituting a practical image display element, especially the pixels constituting a self-emissive display device which is advantageous in terms of power consumption, exhibits a certain degree of angular expansion, even assuming an ideal point light source. Furthermore, each pixel constituting an image display element is, for example, a light-emitting point (point light source). Therefore, in the light distribution of a point light source, light emitted from the light source at an angle greater than a certain degree becomes stray light that does not form an image on the observer's pupil, thus reducing the contrast of the displayed image. That is, this stray light, as light unrelated to the image, is emitted from the lenses constituting the lens array and is visually recognized as background light distributed throughout the observer's field of vision; therefore, the greater its amount, the lower the display contrast.

[0029] The stereoscopic image display device of the present invention provides a directional control layer between the image display element and the lens array, thereby reducing stray light components. As described above, the stereoscopic image display device 10 of the example figure provides an anisotropic absorption layer 14 as a directional control layer between the image display element 12 and the microlens array 16, thereby reducing stray light components. The stereoscopic image display device of the present invention has one or more of the following as a directional control layer: an anisotropic absorption layer 14, a diffraction element, a metasurface structure and polarizer, a phase difference layer and polarizer stack, selected from the example shown in the figure. That is, the stereoscopic image display device of the present invention has an ultrafine structure or a diffraction-type optical path control element and a directional control layer that uses angle-selective reflection or absorption on a flat plate as a directional control layer. Therefore, the desired stray light removal effect can be achieved without precise alignment of the directional control layer with the light-emitting elements (pixels) of the image display element, thereby improving contrast. In particular, in order to display stereoscopic images with a natural sense of depth, when using high-resolution image display elements exceeding 100ppi, any misalignment will affect the display contrast. Therefore, the aforementioned orientation control layer is necessary.

[0030] To display naturally perceptible stereoscopic images using a stereoscopic imaging device, an angular separation capability approximately half the distance between human pupils is required. Furthermore, the average distance between human pupils is about 5 cm. Therefore, assuming utilization at a distance of approximately 1 meter from the stereoscopic image display device, a single pixel (light-emitting point) on the image display element only needs to be reconfigured within an angle range of approximately 1.5°. As an example, in the case of a microlens array using a material with a refractive index of 1.6 and multiple lenses with a radius of curvature of 1 mm and an outer diameter of 0.8 mm, in order to achieve this configuration, the calculation is that the interval between the light emitted from adjacent pixels (light-emitting points) is about 0.02 mm. Assuming that the light-emitting elements constituting each pixel are point light sources, light emitted at angles exceeding this range becomes stray light that reduces the display contrast, as it falls within the range of light entering the pupil of an observer from adjacent pixels and thus forming the image. Therefore, it is preferable to set a cone with the aforementioned interval (0.02 μm) as the diameter of the base and the distance from the light-emitting element to the lens as the height, and to remove light outside this cone. Furthermore, if the distance from the light-emitting element to the surface formed by the outer diameter of the lens is assumed to be 0.4 mm, then light outside the range of ±2.5° is preferably removed relative to the direction parallel to the optical axis of the lens. In other words, the surface formed by the outer diameter of the lens refers to the planar surface of the microlens array.

[0031] For example, as an image display element, assuming a micro-LED display element, the light distribution from the bare chip as a light-emitting element is assumed to be as follows: Figure 2 and Figure 3 The light distribution shown is a uniformly diffused type from a point light source. At this point, more than 90% of the light emitted from the light-emitting element becomes stray light, causing a decrease in display contrast. In contrast, the following scenario is simulated: an anisotropic absorption layer is provided containing dichroic pigments, with its transmittance center axis aligned with the normal direction, i.e., the normal direction of the plane of the lens array (the normal direction of the main surface of the layer) as described above. As an example, within any cross-section of the anisotropic absorption layer, the transmittance of the anisotropic absorption layer relative to the incident angle of light is as follows: Figure 4 As shown. If this anisotropic absorption layer is disposed on the image display surface side (light emitting surface side) of the image display element, it will have the following properties: Figure 2 and Figure 3 The light intensity distribution of the light emitted by the light-emitting element shown is as follows: Figure 5 It changes as shown. As a result, the amount of light that becomes stray light can be reduced to about 60% compared to the light emitted from the bare chip.

[0032] That is, according to the stereoscopic image display device 10 of the present invention, the anisotropic absorption layer 14 can absorb light from the range of adjacent pixels that become stray light from the light emitted from each pixel (light-emitting element / light-emitting point) of the self-emissive image display element 12, and selectively incident light that travels in the normal direction through the observer's pupil onto the microlens array 16. As a result, the stereoscopic image display device 10 of the present invention can suppress the decrease in display contrast caused by stray light and display a stereoscopic image with high display contrast.

[0033] In the stereoscopic image display device 10 of the present invention, the anisotropic absorption layer 14 contains a dichroic material, and the central axis of transmittance is parallel to the normal direction. As described above, the main surface of the anisotropic absorption layer 14 is parallel to the planar surface of the microlens array 16. Therefore, an example of anisotropic absorption layer 14 is a layer in which the dichroic material is oriented perpendicularly to the main surface of the layer.

[0034] In this invention, dichroic substances refer to pigments whose absorbance varies depending on direction. Dichroic substances may or may not exhibit liquid crystal properties.

[0035] There are no particular limitations on dichroic substances. Examples include visible light absorbing substances (dichroic pigments), luminescent substances (fluorescent substances, phosphorescent substances), ultraviolet light absorbing substances, infrared light absorbing substances, nonlinear optical substances, carbon nanotubes, and inorganic substances (e.g., quantum rods). Previously known dichroic substances (dichroic pigments) can be used. Specifically, examples include paragraphs

[0067] to

[0071] of Japanese Patent Application Publication No. 2013-228706, paragraphs

[0008] to

[0026] of Japanese Patent Application Publication No. 2013-227532, paragraphs

[0008] to

[0015] of Japanese Patent Application Publication No. 2013-209367, paragraphs

[0045] to

[0058] of Japanese Patent Application Publication No. 2013-14883, paragraphs

[0012] to

[0029] of Japanese Patent Application Publication No. 2013-101328, paragraphs

[0009] to

[0017] of Japanese Patent Application Publication No. 2013-37353, and paragraph

[0051] of Japanese Patent Application Publication No. 2013-37353.

[0065] paragraphs,

[0049] to

[0073] paragraphs of Japanese Patent Application Publication No. 2012-63387,

[0016] to

[0018] paragraphs of Japanese Patent Application Publication No. Hei 11-305036,

[0009] to

[0011] paragraphs of Japanese Patent Application Publication No. 2001-133630,

[0030] to

[0169] paragraphs of Japanese Patent Application Publication No. 2011-215337,

[0021] to

[0075] paragraphs of Japanese Patent Application Publication No. 2010-106242,

[0011] to

[0025] paragraphs of Japanese Patent Application Publication No. 2010-215846,

[0017] to

[0065] paragraphs of Japanese Patent Application Publication No. 2011-048311. Paragraph 0069, paragraphs

[0013] to

[0133] of Japanese Patent Application Publication No. 2011-213610, paragraphs

[0074] to

[0246] of Japanese Patent Application Publication No. 2011-237513, paragraphs

[0005] to

[0051] of Japanese Patent Application Publication No. 2016-006502, paragraphs

[0014] to

[0032] of Japanese Patent Application Publication No. 2018-053167, paragraphs

[0014] to

[0033] of Japanese Patent Application Publication No. 2020-11716, paragraphs

[0005] to

[0041] of International Publication No. 2016 / 060173, paragraphs

[0008] to

[0041] of International Publication No. 2016 / 136561. Paragraph 0062, paragraphs

[0014] to

[0033] of International Publication No. 2017 / 154835, paragraphs

[0014] to

[0033] of International Publication No. 2017 / 154695, paragraphs

[0013] to

[0037] of International Publication No. 2017 / 195833, paragraphs

[0014] to

[0034] of International Publication No. 2018 / 164252, paragraphs

[0021] to

[0030] of International Publication No. 2018 / 186503, paragraphs

[0043] to

[0063] of International Publication No. 2019 / 189345, paragraphs

[0043] to

[0085] of International Publication No. 2019 / 225468,The dichroic substances described in International Publication No. 2020 / 004106, paragraphs

[0050] to

[0074] , and International Publication No. 2021 / 044843, paragraphs

[0015] to

[0038] .

[0036] In this invention, two or more dichroic substances can be used together. For example, from the viewpoint of making the anisotropic absorption layer 14 nearly black, it is preferable to use at least one dichroic material having a maximum absorption wavelength in the wavelength range of 370 to 550 nm and at least one dichroic material having a maximum absorption wavelength in the wavelength range of 500 to 700 nm.

[0037] There is no particular limitation on the method of forming the anisotropic absorption layer 14, and various known methods that can orient the dichroic material perpendicularly to the main surface of the layer can be used. As an example, from the viewpoint of oriented dichroic materials with high orientation degree, a method of forming a liquid crystal composition containing a liquid crystal compound together with the aforementioned dichroic material is preferred. In this invention, the liquid crystal compound is a liquid crystal compound that does not exhibit dichroism. The liquid crystal compound can be either a low-molecular-weight liquid crystal compound or a high-molecular-weight liquid crystal compound, but from the viewpoint of obtaining a high degree of orientation, a high-molecular-weight liquid crystal compound is preferred. Here, "low-molecular-weight liquid crystal compound" refers to a liquid crystal compound that does not have repeating units in its chemical structure. And "high-molecular-weight liquid crystal compound" refers to a liquid crystal compound that has repeating units in its chemical structure. Examples of low-molecular-weight liquid crystal compounds include those described in Japanese Patent Application Publication No. 2013-228706. Examples of polymeric liquid crystal compounds include, for instance, the thermotropic liquid crystal polymer described in Japanese Patent Application Publication No. 2011-237513. Furthermore, the polymeric liquid crystal compound may have crosslinking groups (e.g., acryloyl and methacryloyl groups) at its ends. Liquid crystal compounds can be used alone or in combination with two or more. From the perspective of achieving better orientation of the anisotropic absorption layer 14, the liquid crystal compound preferably comprises a polymeric liquid crystal compound. Furthermore, the liquid crystal composition may contain solvents, polymerization initiators, surface modifiers, alignment agents, and other components.

[0038] This anisotropic absorption layer 14 can be formed using known methods. For example, in the formation of the anisotropic absorption layer 14 using the liquid crystal composition, firstly, the liquid crystal composition is coated onto an alignment film that imparts an orientation to the liquid crystal compound. Then, by heating and / or cooling the liquid crystal composition, or by repeatedly heating and cooling, the liquid crystal compound is oriented in the thickness direction. Through this orientation of the liquid crystal compound, the dichroic material is also oriented in the thickness direction in the same way. Then, as needed, the liquid crystal composition is cured by ultraviolet irradiation or the like, thereby forming an anisotropic absorption layer 14 in which the dichroic material is oriented in the thickness direction.

[0039] As described above, in the stereoscopic image display device of the present invention, cylindrical lenses can preferably be used as the lens array. As mentioned above, cylindrical lenses can utilize various known cylindrical lenses used for displaying stereoscopic images to the naked eye.

[0040] Here, as Figure 6 As conceptually illustrated, when using a cylindrical lens 20 as a lens array, it is preferable to provide a polarizer 24 between the image display element 12 and the anisotropic absorption layer 14. Furthermore, in Figure 6 In order to simplify the accompanying drawings and make the structure of the present invention easier to understand, only two lenses constituting the cylindrical lens 20 are shown. However, it is well known that a cylindrical lens is actually formed by arranging multiple elongated lenses in a direction orthogonal to the length direction. At this time, the polarizer 24 is configured such that the transmission axis 24a is orthogonal to the longitudinal direction of the lens constituting the cylindrical lens. That is, the polarizer 24 blocks linearly polarized light along the longitudinal direction of the lens constituting the cylindrical lens.

[0041] As described above, the anisotropic absorption layer 14 contains a dichroic material and has a transmittance central axis in the normal direction. That is, the anisotropic absorption layer 14 is a layer formed by oriented the dichroic material perpendicular to the main surface. This anisotropic absorption layer 14 transmits light incident along the normal direction, while absorbing light incident from the tilted direction relative to the normal. Here, the anisotropic absorption layer 14 preferably absorbs linearly polarized light in light incident from an oblique direction relative to the normal direction of the main surface, but has a low absorption rate for linearly polarized light in directions orthogonal to the normal. In other words, the anisotropic absorption layer 14 preferably absorbs linearly polarized light in light incident from an oblique direction in the orientation direction of the dichroic material, but has a low absorption rate for linearly polarized light in directions orthogonal to the orientation direction of the dichroic material. That is, the anisotropic absorption layer 14 preferably absorbs linearly polarized light in the direction orthogonal to the length direction of the lens constituting the cylindrical lens from the light incident from the oblique direction, but the absorption rate of linearly polarized light in the length direction of the lens constituting the cylindrical lens is low.

[0042] In contrast, such as Figure 6 As shown, when the cylindrical lens 20 is used as a lens array, it is preferable to provide a polarizer 24 between the image display element 12 and the anisotropic absorption layer 14, which sets the transmission axis 24a in a direction orthogonal to the length direction of the lens constituting the cylindrical lens 20. Thus, in the light incident obliquely into the anisotropic absorption layer 14, the linearly polarized light in the longitudinal direction of the lens constituting the low-absorption cylindrical lens 20 based on the anisotropic absorption layer 14 can be blocked by the polarizer 24, that is, the light can be removed in advance, so that only the obliquely incident light of the linearly polarized light in the orthogonal direction is incident into the anisotropic absorption layer 14. as a result, Figure 6 The stereoscopic image display device shown can further reduce the amount of light entering the range of adjacent pixels that become stray light, and more appropriately suppress the decrease in display contrast caused by stray light, thereby displaying a stereoscopic image with high contrast.

[0043] The following shows simulation results when a polarizer 24 is provided between the anisotropic absorption layer 14 and the image display element 12. like Figure 6 As shown, when the transmission axis 24a is aligned with the direction orthogonal to the length direction of the lens and a polarizer 24 is provided between the anisotropic absorption layer 14 and the image display element 12, the transmittance of the stack of the polarizer and the anisotropic absorption layer relative to the incident angle of light is as follows: Figure 7 As shown. Figure 8 As shown, this laminate makes the material from the above-mentioned Figure 3 The light intensity distribution of the light emitted by the light-emitting element, as shown in the light intensity distribution diagram, changes. Therefore, compared with the case where light is directly incident from the light-emitting element onto the cylindrical lens 20, the amount of light that can become stray light is reduced to about 20%. The results indicate that in a stereoscopic image display device that uses a cylindrical lens 20 as a lens array and an anisotropic absorption layer 14 as a directionality control layer, a polarizer 24 is configured such that the longitudinal direction of the lens constituting the cylindrical lens 20 is orthogonal to the direction of the transmission axis 24a, thereby achieving a particularly good improvement in display contrast.

[0044] For example, even if the light-emitting element is a surface-emitting type, such as an OLED display element, when using a high-resolution display element with a resolution of over 100ppi, the light-emitting element is small enough to be simulated as a point light source, even in surface-emitting types like OLEDs. Therefore, the same effect as described above can be achieved.

[0045] Optical plate 24 can utilize various known linear polarizers (linear polarizers). Therefore, the optical element 24 can be either reflective or absorptive. Examples of polarizers 24 include iodine-based polarizers, dye-based polarizers utilizing dichroic dyes, polyene-based polarizers, wire grid polarizers, and thin films with stretched dielectric multilayers as described in Japanese Patent Application Publication No. 2011-053705.

[0046] As described above, in the stereoscopic image display device of the present invention, except Figure 1 and Figure 6 In addition to the anisotropic absorption layer 14 containing dichroic material, the directional control layer can also utilize a stack of diffractive elements, metasurface structures and polarizers, and a phase difference layer and polarizers. In addition, these directional control layers can be used in multiples as needed.

[0047] Specifically, as a diffraction element that serves as a directional control layer, a diffraction element can be used that utilizes the diffraction phenomenon to diffract light components at a high angle relative to the optical axis, and sets the direction of the optical axis, i.e., the normal direction. Examples of such diffraction elements include those composed of surface relief holograms, volume holograms, and liquid crystal diffraction elements.

[0048] Furthermore, as a directional control layer, it can also be a transmissive metasurface structure with the direction of light incident at an angle relative to the normal direction set to the normal direction. Metasurface structures can be formed by arranging multiple microstructures corresponding to the wavelength of the displayed stereoscopic image using various known metasurface structures. Regarding such metasurface structures, they can be designed using known methods based on the transmission characteristics of the target light (electromagnetic wave). As an example, commercially available simulation software is used to calculate the amplitude and phase of the light transmitted through the microstructures, and the arrangement of the microstructures is set to achieve the distribution of the phase modulation (refractive index) as the target.

[0049] Furthermore, as a directional control layer, a stack consisting of a polarizer, a phase difference layer, and a polarizer arranged in sequence, with the transmission axes of the polarizers arranged parallel or orthogonal to each other, can be used. More specifically, an example is illustrated by a stack having a polarizer, a λ / 2 waveplate, and another polarizer in sequence, with the transmission axes of the polarizers orthogonal to each other. The λ / 2 plate is configured at 45° relative to the transmission axes of each polarizer, exhibiting negative biaxiality (nx > ny > nz). In this stack, as an example, light incident from the normal direction transmits only P-polarized light in the first polarizer, converts this P-polarized light to S-polarized light in the λ / 2 plate, and transmits S-polarized light in the second polarizer. In contrast, the larger the polar angle of light incident from the tilted direction, the more the phase change is amplified by the retardation Rth in the thickness direction of the λ / 2 plate, thus becoming elliptically polarized light, and the transmittance of the second polarizer decreases. As a result, the directivity of the light can be controlled primarily by treating the transmitted light as light in the normal direction. In other words, the polar angle refers to the angle relative to the normal. The larger the thickness retardation Rth of λ / 2, the greater the angular selectivity it exhibits. λ / 2 plates can be mixed-orientation plates. In this stack, various known polarizers and retardation layers can be used. Furthermore, the polarizer can be either an absorptive or a reflective type. Furthermore, in this stack, as long as the polarizer, phase difference layer and polarizer are arranged in this order, they can be stacked with other layers in between, and can also be laminated to form a stacked structure.

[0050] However, as a directional control layer, it is more preferable to use a layer that can appropriately absorb and remove light that has an angle relative to the normal direction from the light emitted from the image display element 12 (light-emitting element), and can set the transmittance of the light in the normal direction to be relatively high, thereby improving the light utilization efficiency. Furthermore, it is also more preferable to use a layer that requires fewer layers and thus results in less interface reflection. Figure 1 and Figure 6 The anisotropic absorption layer 14 containing dichroic pigments is shown. That is, in the stereoscopic image display device of the present invention, the optical sheet of the present invention is preferably used, which has a lens array and an anisotropic absorption layer containing dichroic pigments. One surface of the lens array is planar and the other surface is curved. An anisotropic absorption layer is disposed on the planar surface side of the lens array, and the transmittance central axis of the anisotropic absorption layer is parallel to the normal direction of the planar surface of the lens array.

[0051] The stereoscopic image display device and optical sheet of the present invention have been described in detail above. However, the present invention is not limited to the above examples. Various improvements and modifications can be made without departing from the spirit of the present invention. Industrial availability

[0052] It can be preferably used in head-mounted displays such as VR (Virtual Reality) goggles. Symbol Explanation

[0053] 10-Stereoscopic image display device, 12-Image display element, 14-Anisotropic absorption layer, 16-Microlens array, 20-Columnar lens, 24-Polarizer.

Claims

1. A stereoscopic image display device, comprising, in sequence: A lens array, which arranges multiple lenses in a planar shape; Directional control layer; and Self-emissive image display element, One surface of the lens array is planar, and the other surface of the lens array has a curved shape. The directional control layer is disposed on the planar side of the lens array. The directional control layer is selected from the group consisting of an anisotropic absorption layer containing dichroic material, a diffraction element, a metasurface structure, and a stack of a polarizer and a phase difference layer and a polarizer. The directional control layer is the layer whose brightness is highest in the normal direction of the other surface of the directional control layer when light is shone from one surface side of the directional control layer.

2. The stereoscopic image display device according to claim 1, wherein, The directional control layer is an anisotropic absorption layer containing the dichroic material, and the central axis of transmittance is parallel to the normal direction of the planar surface of the lens array.

3. The stereoscopic image display device according to claim 2, wherein, The anisotropic absorption layer comprises a liquid crystal compound that is vertically oriented.

4. The stereoscopic image display device according to claim 1 or 2, wherein, The lens array is a cylindrical lens.

5. The stereoscopic image display device according to claim 4, wherein, A polarizer is also provided between the image display element and the orientation control layer. The transmission axis of the polarizer is orthogonal to the length direction of the lens constituting the cylindrical lens.

6. The stereoscopic image display device according to claim 1 or 2, wherein, The lens array is a microlens array.

7. An optical sheet comprising: a lens array arranging a plurality of lenses in a planar configuration; and an anisotropic absorption layer comprising a dichroic material, wherein, One surface of the lens array is planar, and the other surface of the lens array has a curved shape. The anisotropic absorption layer is disposed on the planar side of the lens array. The transmittance central axis of the anisotropic absorption layer is parallel to the normal direction of the planar surface of the lens array.

8. The optical sheet according to claim 7, wherein, The anisotropic absorption layer comprises a liquid crystal compound that is vertically oriented.

9. The optical sheet according to claim 7 or 8, wherein, The lens array is a cylindrical lens.

10. The optical sheet according to claim 9, wherein, A polarizer is also provided on the side of the anisotropic absorption layer opposite to the lens array side. The transmission axis of the polarizer is orthogonal to the length direction of the lens constituting the cylindrical lens.

11. The optical sheet according to claim 7 or 8, wherein, The lens array is a microlens array.

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