Image display element and image display device comprising same

Abstract

[Problem] To provide an image display element capable of improving, in accordance with the position of a pupil, the quantity of light that enters an observation pupil to obtain a bright observation image. [Solution] This image display element is characterized by comprising a pixel and a nanostructure that is disposed on the pixel, wherein the nanostructure provides light from a light-emitting layer of the pixel with a phase difference distribution the center of which is a first center different from the center of the light-emitting layer in the radial direction of the nanostructure, and the first center is disposed along the circumferential direction of the nanostructure.

Description

Image display element and image display device having the same

[0001] This disclosure relates to an image display element and an image display device having the same.

[0002] In an image display device that allows an observer to view an image as an enlarged virtual image, it is necessary to deliver light from the pixels according to the position of the pupil. Figure 5 shows the relationship between the position of the observer's pupil and the directivity of light from pixel P, illustrating how the observer is viewing the light from pixel P through the optical system L. SP1 is the pupil when the observer is fixated on pixel P, and SP2 is the pupil when the observer is fixated on the area surrounding pixel P. The amount of light entering pupils SP1 and SP2 is determined by the directivity of the light from pixel P. When the observer is fixated on pixel P, the amount of light needs to be increased, while when the observer is fixated on the area surrounding pixel P, the amount of light does not need to be increased. Therefore, it is necessary to increase the directivity of light near the vertical direction. Patent Document 1 discloses a configuration that can generate light whose intensity and direction are modulated by an optical modulator.

[0003] International Publication No. 2013 / 086046

[0004] However, in the configuration of Patent Document 1, since light from multiple pixels is extracted by the same microlens, there are concerns that the resolution of the pixels may decrease or the efficiency of light extraction from each pixel may decrease in a 2D display.

[0005] To achieve the above objective, an image display element according to the present disclosure comprises a pixel and a nanostructure disposed on the pixel, wherein the nanostructure imparts a phase difference distribution to the light from the light-emitting layer, centered on a first center different from the center of the light-emitting layer of the pixel in the radial direction of the nanostructure, and the first center is arranged along the circumferential direction of the nanostructure.

[0006] This provides an image display element that can improve the amount of light entering the pupil according to its position, thereby achieving a brighter observation image.

[0007] This is a conceptual diagram of a nanostructure according to the first embodiment. This is a conceptual diagram of a nanostructure according to the second embodiment. This is a schematic cross-sectional diagram showing an example of a display device. This is a conceptual diagram representing an example of an image display device. This is a diagram showing the relationship between the position of the observer's pupil and the directivity of light from the pixels, as a conventional example.

[0008] The embodiments disclosed herein will now be described in detail with reference to the drawings. In each drawing, the same reference numeral is used for identical components, and redundant descriptions are omitted.

[0009] The image display element disclosed herein comprises a pixel and a nanostructure disposed on the pixel. The nanostructure imparts a phase difference distribution to the light from the light-emitting layer, centered on a first center different from the center of the light-emitting layer of the pixel in the radial direction of the nanostructure. The first center is positioned along the circumferential direction of the nanostructure. The image display element disclosed herein can be used, for example, in an image display device that causes an image to be observed by an observer as an enlarged virtual image by an optical system.

[0010] First, the nanostructure and the phase difference distribution provided by the nanostructure will be described. The nanostructure in this embodiment includes multiple unit structures (metaatoms). Each of the multiple unit structures has a sub-wavelength shape and dimensions. By controlling the amount of phase delay (amount of phase modulation) by the arrangement of the unit structures, the nanostructure can provide a desired phase difference distribution to the light from the light-emitting layer. The deflection effect of the nanostructure is represented by the phase difference distribution. For example, if the deflection effect of the nanostructure is a spherical lens, the phase difference distribution ψ ０ It can be expressed by the following formula.

[0011]

[0012] Here, f is the focal length of the spherical lens, r is the distance from the center of the spherical lens, and λ is the wavelength of the incident light.

[0013] Based on the above, nanostructures can impart a phase difference distribution centered on a desired position to the light emitted from the light-emitting layer, depending on the arrangement of the unit structures.

[0014] The unit structures constituting the nanostructures can be any shape that provides a sub-wavelength with a desired phase delay, and can be various shapes such as cylinders, rectangular prisms, or cross shapes. The arrangement of the unit structures may be a single shape or a combination of multiple shapes.

[0015] Furthermore, the phase difference distribution may more generally be a phase difference distribution expressed by the following polynomial as a rotational symmetry plane from the center.

[0016]

[0017] Here, h is the distance from the center.

[0018] Such a phase difference distribution ensures design freedom for the orientation characteristics of light obtained by the nanostructure. The relationship between the configuration of the center of the phase difference distribution and the obtained orientation characteristics of light will be described later. [First Embodiment] Figure 1 is a conceptual diagram of the nanostructure of this embodiment. Figure 1(A) shows the positional relationship between the center 1001 of the light-emitting layer 1000 of a pixel when viewed from the surface and the center (first center) 3000 of the phase difference distribution provided by the nanostructure 2000. The nanostructure 2000 provides a phase difference distribution to the light from the light-emitting layer 1000 that is centered on a first center 3000, which is different from the center 1001 of the light-emitting layer 1000, in the radial direction of the nanostructure 2000. The first center 3000 is arranged along the circumferential direction of the nanostructure 2000. Here, the radial direction and the circumferential direction correspond to the directions shown in Figure 1(A).

[0019] FIG. 1(B) is a cross-sectional view taken along line A-A' in FIG. 1(A). A region including the center of one retardation distribution from the center 1001 of the light-emitting layer 1000 is defined as region A11, and a region including the center of the other retardation distribution from the center 1001 of the light-emitting layer 1000 is defined as region A12. Light emitted from the light-emitting layer 1000 is deflected into a first orientation angle distribution R11 by the deflection action of the region A11, and deflected into a second orientation angle distribution R12 by the deflection action of the region A12. Since the first orientation angle distribution R11 and the second orientation angle distribution R12 overlap in an angle range close to the vertical direction (0°), the directivity near the vertical direction can be enhanced. For cross-sections other than that cut along line A-A', since there is isotropy in the circumferential direction of the nanostructure 2000, the directivity near the vertical direction can be similarly enhanced.

[0020] As described above, in the present embodiment, the nanostructure 2000 imparts a retardation distribution centered on a first center 3000 different from the center 1001 of the light-emitting layer 1000 of the pixel in the radial direction of the nanostructure 2000 to light from the light-emitting layer 1000. The first center 3000 is arranged along the circumferential direction of the nanostructure 2000. With this configuration, the directivity of light from the pixel is controlled, and in particular, the directivity near the vertical direction can be enhanced.

[0021] The upper limit θ of the first orientation angle distribution R11 １１＋ and the lower limit θ １１－ , and the upper limit θ of the second orientation angle distribution R12 １２＋ and the lower limit θ １２－ are each represented by the following formulas (1) to (4). Note that each value is an angle formed with the normal line of the light-emitting layer 1000, with counterclockwise defined as positive.

[0022] θ １１＋ =tan －１ {(ΔY+Y) / f}  (1)  θ １１－ =tan －１ {(ΔY−Y) / f}  (2)  θ １２＋ =tan －１ {−(ΔY−Y) / f}  (3)  θ １２－ =tan －１{-(ΔY+Y) / f} (4) where f is the focal length of the nanostructure 2000. Y is the radial length of the light-emitting layer 1000 (the size of the light-emitting layer 1000). ΔY is the distance between the first center 3000 and the center 1001 of the light-emitting layer 1000.

[0023] FIG. 1(C) shows the orientation characteristics of light obtained by the nanostructure 2000. It is preferable that the distance between the first center 3000 and the center 1001 of the light-emitting layer 1000 is shorter than the radial length of the light-emitting layer 1000, that is, ΔY<Y is satisfied. Thereby, θ １１－ <θ １２＋ is satisfied, and since the first orientation angle distribution R11 and the second orientation angle distribution R12 overlap, the directivity near the vertical direction can be enhanced. Even for cross sections other than the one cut along line A-A', since there is isotropy in the circumferential direction of the nanostructure 2000, the directivity near the vertical direction can be similarly enhanced.

[0024] The value ΔY / Y preferably satisfies the following conditional expression (5).

[0025] 0.10 < ΔY / Y < 0.90 (5) Conditional expression (5) defines the position of the first center 3000. When the value exceeds the upper limit of conditional expression (5), the overlapping angular region of the first orientation angle distribution R11 and the second orientation angle distribution R12 becomes too large, and the directivity near the vertical direction does not relatively increase, which is not preferable. When the value falls below the lower limit of conditional expression (5), the overlapping angular region of the first orientation angle distribution R11 and the second orientation angle distribution R12 becomes too small, which is not preferable.

[0026] It is more preferable to set the numerical range of conditional expression (5) to the numerical range of the following conditional expression (5a).

[0027] 0.15 < ΔY / Y < 0.85 (5a) Further, it is even more preferable to set the numerical range of conditional expression (5) to the numerical range of the following conditional expression (5b).

[0028] 0.20 < ΔY / Y < 0.80 (5b) Hereinafter, a specific configuration of the present embodiment will be described. In each numerical example, the relationship between the configuration of the nanostructure 2000 (the focal length, the distance between the first center 3000 and the center 1001 of the light-emitting layer 1000) and the obtained radiation angle distribution is shown in Table 1. In each numerical example, the radial length Y of the light-emitting layer 1000 is set to 1.0 µm. The angular width of the orientation angle distribution is set by the focal length of the nanostructure 2000. When the focal length increases, the angular width of the orientation angle distribution decreases, and when the focal length decreases, the angular width of the orientation angle distribution increases. Since the distance between the first center 3000 and the center 1001 of the light-emitting layer 1000 is shorter than the radial length of the light-emitting layer 1000, the first orientation angle distribution R11 and the second orientation angle distribution R12 overlap, and the directivity near the vertical direction can be improved. The overlapping angular region of the first orientation angle distribution and the second orientation angle distribution R12 is set by the distance between the first center 3000 and the center 1001 of the light-emitting layer 1000. When the distance between the first center 3000 and the center 1001 of the light-emitting layer 1000 increases, the overlapping angular region of the orientation angle distribution increases, so the directivity near the vertical direction can be further improved.

[0029]

[0030] [Second Embodiment] In the present embodiment, the nanostructure imparts, to light from the light-emitting layer, a phase difference distribution centered on a first center different from the center of the light-emitting layer, and a phase difference distribution centered on a second center different from the first center, in the radial direction of the nanostructure.

[0031] FIG. 2 is a conceptual diagram of the nanostructure of the present embodiment. FIG. 2(A) shows the positional relationship among the center 1001 of the light-emitting layer 1000, the first center 3000, and the second center 4000. FIG. 2(B) is a cross-sectional view taken along line B-B' in FIG. 2(A). The regions to which the first phase difference distribution is imparted are defined as peripheral regions A21 and A22, and the region to which the second phase difference distribution is imparted is defined as a central region A23. Light emitted from the light-emitting layer 1000 is deflected into a first orientation angle distribution R21 by the deflection effect of the peripheral region A21, a second orientation angle distribution R22 by the deflection effect of the peripheral region A22, and a third orientation angle distribution R23 by the deflection effect of the central region A23.

[0032] The upper limit θ of the first orientation angle distribution R21 ２１＋ and lower limit θ ２１－ , the upper limit θ of the second orientation angle distribution R22 ２２＋ and lower limit θ ２２－ , the upper limit θ of the third orientation angle distribution R23 ２３＋ and lower limit θ ２３－ These are expressed by the following equations (6) to (11). Note that each value is the angle made with the normal of the light-emitting layer 1000, with counterclockwise rotation being considered positive.

[0033] θ ２１＋ = tan －１ {(ΔY+Y) / f} (6) θ ２１－ = tan －１ {(ΔY-Y) / f} (7) θ ２２＋ = tan －１ {-(ΔY-Y) / f} (8) θ ２２－ = tan －１ {-(ΔY+Y) / f} (9) θ ２３＋ = tan －１ (Y / f) (10) θ ２３－ = tan －１ (-Y / f) (11) Here, f is the focal length of the nanostructure 2000. Y is the radial length of the light-emitting layer 1000. ΔY is the distance between the first center 3000 and the center 1001 of the light-emitting layer 1000.

[0034] Figure 2(C) shows the light orientation characteristics obtained by the nanostructure 2000. The distance between the first center 3000 and the center 1001 of the light-emitting layer 1000 is preferably longer than twice the radial length of the light-emitting layer 1000, i.e., ΔY / 2 > Y. This allows θ ２２＋ <θ ２３－ and θ ２３＋ <θ ２１－Therefore, the first orientation angle distribution R21 and the third orientation angle distribution R23 do not overlap, and the second orientation angle distribution R22 and the third orientation angle distribution R23 do not overlap. Thus, the directivity near the vertical direction can be enhanced. For cross-sections other than those cut along the B-B' line, the nanostructure 2000 is isotropic with respect to the circumferential direction, so similarly, the directivity near the vertical direction can be enhanced.

[0035] The value ΔY / Y preferably satisfies the following condition (12).

[0036] 2.10 < ΔY / Y < 5.00 (12) Condition (12) defines the position of the first center 3000. If the upper limit of condition (12) is exceeded, the angular ranges of the first orientation angle distribution R21 and the second orientation angle distribution R22 become too large, which is undesirable because the directivity near the vertical does not increase relatively. If the lower limit of condition (12) is exceeded, the angular ranges of the first orientation angle distribution R21 and the second orientation angle distribution R22 become too close to the third orientation angle distribution R23, which is undesirable because the directivity near the vertical does not increase relatively.

[0037] Furthermore, it is more preferable to set the numerical range of conditional expression (12) to the numerical range of conditional expression (12a) below.

[0038] 2.20 < ΔY / Y < 4.50 (12a) Furthermore, it is even more preferable to set the numerical range of conditional equation (13) to the numerical range of conditional equation (12b) below.

[0039] 2.30 < ΔY / Y < 4.00 (12b) The specific configuration of this embodiment will be described below. In each numerical example, the relationship between the configuration of the nanostructure 2000 (focal length, distance between the first center 3000 and the center 1001 of the light-emitting layer 1000) and the obtained radiation angle distribution is shown in Table 2. In each numerical example, the radial length Y of the light-emitting layer is set to 1.0 μm. The angular width of the orientation angle distribution is set by the focal length of the nanostructure. As the focal length increases, the angular width of the orientation angle distribution decreases, and as the focal length decreases, the angular width of the orientation angle distribution increases. The distance between the first center 3000 and the center 1001 of the light-emitting layer 1000 is longer than twice the radial length of the light-emitting layer 1000. Therefore, the first orientation angle distribution R21 and the third orientation angle distribution R23 do not overlap, and the second orientation angle distribution R22 and the third orientation angle distribution R23 do not overlap. This allows for improved directivity in the vertical direction.

[0040]

[0041] The following describes the configuration of the pixels (organic light-emitting elements) in this embodiment. [Configuration of Organic Light-Emitting Elements] The organic light-emitting element is provided on a substrate by forming an insulating layer, a first electrode, an organic compound layer, and a second electrode. A protective layer, a color filter, a microlens, etc., may be provided on the cathode. If a color filter is provided, a planarization layer may be provided between it and the protective layer. The planarization layer can be made of acrylic resin or the like. The same applies when a planarization layer is provided between the color filter and the microlens.

[0042] [Substrate] Examples of substrates include quartz, glass, silicon wafers, resins, and metals. Switching elements such as transistors and wiring may be provided on the substrate, and an insulating layer may be provided on top of them. The insulating layer can be made of any material that allows contact holes to be formed so that wiring can be formed between it and the first electrode, and that ensures insulation from wiring that is not connected. For example, resins such as polyimide, silicon oxide, silicon nitride, etc. can be used. [Electrodes] A pair of electrodes can be used. The pair of electrodes may be an anode and a cathode. When an electric field is applied in the direction in which the organic light-emitting element emits light, the electrode with the higher potential is the anode, and the other is the cathode. Alternatively, the electrode that supplies holes to the light-emitting layer may be the anode, and the electrode that supplies electrons may be the cathode.

[0043] The anode material should ideally have the largest possible work function. For example, elemental metals such as gold, platinum, silver, copper, nickel, palladium, cobalt, selenium, vanadium, and tungsten, or mixtures containing these, can be used. Alloys combining these metals, as well as metal oxides such as tin oxide, zinc oxide, indium oxide, tin-indium oxide (ITO), and zinc-indium oxide, can also be used. Conductive polymers such as polyaniline, polypyrrole, and polythiophene can also be used.

[0044] These electrode materials may be used individually or in combination of two or more types. Furthermore, the anode may consist of a single layer or multiple layers.

[0045] When used as a reflective electrode, materials such as chromium, aluminum, silver, titanium, tungsten, molybdenum, or alloys or laminates thereof can be used. It is also possible to use the above materials to function as a reflective film without serving as an electrode. Furthermore, when used as a transparent electrode, oxide transparent conductive layers such as indium tin oxide (ITO) or indium zinc oxide can be used, but are not limited to these. Photolithography technology can be used to form the electrodes.

[0046] On the other hand, materials with a small work function are preferred for the cathode. Examples include alkali metals such as lithium, alkaline earth metals such as calcium, and elemental metals or mixtures containing these, such as aluminum, titanium, manganese, silver, lead, and chromium. Alternatively, alloys combining these elemental metals can also be used. For example, magnesium-silver, aluminum-lithium, aluminum-magnesium, silver-copper, and zinc-silver can be used. Metal oxides such as indium tin oxide (ITO) can also be used. These electrode materials may be used individually or in combination of two or more. The cathode may also be a single-layer or multi-layer structure. Among these, silver is preferred, and a silver alloy is even more preferred to reduce silver aggregation. The alloy ratio is not important as long as silver aggregation is reduced. For example, the ratio of silver to other metals may be 1:1, 3:1, etc.

[0047] The cathode may be a top-emission element using an oxide conductive layer such as ITO, or a bottom-emission element using a reflective electrode such as aluminum (Al), and is not particularly limited. The method of forming the cathode is not particularly limited, but using DC and AC sputtering methods is more preferable because it provides good film coverage and makes it easier to reduce resistance. [Pixel separation layer] The pixel separation layer is formed from a silicon nitride (SiN), silicon oxynitride (SiO) film, or silicon oxide (SiO) film formed using chemical vapor deposition (CVD). In order to increase the in-plane resistance of the organic compound layer, it is preferable that the thickness of the organic compound layer, especially the hole transport layer, be thinly deposited on the sidewalls of the pixel separation layer. Specifically, by increasing the taper angle of the sidewalls of the pixel separation layer and the thickness of the pixel separation layer, the thickness of the sidewalls can be thinned by increasing vignetting during deposition.

[0048] On the other hand, it is preferable to adjust the taper angle of the sidewalls of the pixel isolation layer and the thickness of the pixel isolation layer to such an extent that no voids are formed in the protective layer formed on top of it. Since no voids are formed in the protective layer, the occurrence of defects in the protective layer can be reduced. Since the occurrence of defects in the protective layer is reduced, the decrease in reliability, such as the occurrence of dark spots and the occurrence of poor conductivity of the second electrode, can be reduced.

[0049] According to this embodiment, even if the taper angle of the side wall of the pixel isolation layer is not steep, it is possible to effectively suppress charge leakage to adjacent pixels. As a result of this study, it was found that sufficient reduction is possible if the taper angle is in the range of 60 degrees to 90 degrees. The thickness of the pixel isolation layer is preferably between 10 nm and 150 nm. Furthermore, the same effect can be obtained even if the device is composed only of pixel electrodes without a pixel isolation layer. However, in this case, it is preferable that the thickness of the pixel electrode be less than half that of the organic layer, or that the ends of the pixel electrodes be tapered forward to less than 60°, as this reduces short circuits in the organic light-emitting element. [Organic compound layer] The organic compound layer may be formed as a single layer or as multiple layers. When there are multiple layers, they may be called a hole injection layer, hole transport layer, electron blocking layer, light-emitting layer, hole blocking layer, electron transport layer, or electron injection layer depending on their function. The organic compound layer is mainly composed of organic compounds, but may also contain inorganic atoms and inorganic compounds. For example, it may contain copper, lithium, magnesium, aluminum, iridium, platinum, molybdenum, zinc, etc. The organic compound layer may be placed between the first electrode and the second electrode, or it may be placed in contact with the first electrode and the second electrode.

[0050] If there are multiple light-emitting layers, a charge generation section may be provided between the first and second light-emitting layers. The charge generation section may contain an organic compound with a minimum unoccupied molecular orbital energy (LUMO) of -5.0 eV or less. The same applies when the charge generation section is provided between the second and third light-emitting layers. [Protective layer] A protective layer may be provided on the second electrode. For example, by bonding glass with a desiccant on the second electrode, the intrusion of water and other substances into the organic compound layer can be reduced, thereby reducing the occurrence of display defects. In another embodiment, a passivation film of silicon nitride or the like may be provided on the cathode to reduce the intrusion of water and other substances into the organic compound layer. For example, after forming the cathode, the material may be transported to another chamber without breaking the vacuum, and a silicon nitride film with a thickness of 2 μm may be formed by CVD to serve as a protective layer. A protective layer may also be provided using atomic deposition (ALD) after film formation by CVD. The material of the film formed by ALD is not limited, but may be silicon nitride, silicon oxide, aluminum oxide, etc. Silicon nitride may be formed on the film formed by the ALD method using the CVD method. The film formed by the ALD method may have a thinner film thickness than the film formed by the CVD method. Specifically, it may be 50% or less, or even 10% or less. [Color filter] A color filter may be provided on the protective layer. For example, a color filter that takes into account the size of the organic light-emitting element may be provided on a separate substrate and bonded to the substrate on which the organic light-emitting element is provided, or a color filter may be patterned on the protective layer as described above using photolithography technology. The color filter may be made of a polymer. [Planarization layer] A planarization layer may be provided between the color filter and the protective layer. The planarization layer is provided for the purpose of reducing the unevenness of the layer below. It may also be called a material resin layer without limiting its purpose. The planarization layer may be made of an organic compound, and may be low molecular weight or high molecular weight, but high molecular weight is preferred.

[0051] The planarization layer may be provided above and below the color filter, and its constituent materials may be the same or different. Specifically, examples include polyvinylcarbazole resin, polycarbonate resin, polyester resin, ABS resin, acrylic resin, polyimide resin, phenolic resin, epoxy resin, silicone resin, urea resin, etc. [Microlens] The organic light-emitting device has an optical component made of nanostructures on its light-emitting side. The nanostructures are intended to increase the amount of light extracted from the organic light-emitting device and to control the direction of the extracted light. Their functions and preferred configurations are as described above.

[0052] The nanostructure has an arrangement of multiple unit structures. The nanostructure may be patterned on the color filter using photolithography. Alternatively, the nanostructure may be provided on another substrate and bonded to the color filter, or it may be arranged so that there is a gap between the color filter and the substrate. Examples of substrates include quartz, glass, and silicon wafers. The constituent material of the nanostructure may be a thermosetting resin or a photocurable resin depending on the processing process. [Opposite Substrate] An opposite substrate may be provided on the planarization layer. The opposite substrate is called an opposite substrate because it is provided in a position corresponding to the aforementioned substrate. The constituent material of the opposite substrate may be the same as that of the aforementioned substrate. The opposite substrate may be a second substrate if the aforementioned substrate is the first substrate. [Organic Layer] The organic compound layer (hole injection layer, hole transport layer, electron blocking layer, light-emitting layer, hole blocking layer, electron transport layer, electron injection layer, etc.) constituting the organic light-emitting element according to this embodiment is formed by the method shown below.

[0053] The organic compound layer constituting the organic light-emitting element according to this embodiment can be formed using a dry process such as vacuum deposition, ionization deposition, sputtering, or plasma deposition. Alternatively, instead of a dry process, a wet process can be used in which the layer is formed by dissolving the compound in a suitable solvent and applying a known coating method (e.g., spin coating, dipping, casting, LB method, inkjet method, etc.).

[0054] When layers are formed using methods such as vacuum deposition or solution coating, crystallization is less likely to occur, resulting in excellent stability over time. Furthermore, when forming films using coating methods, it is possible to combine the film with an appropriate binder resin.

[0055] Examples of the binder resins mentioned above include, but are not limited to, polyvinylcarbazole resin, polycarbonate resin, polyester resin, ABS resin, acrylic resin, polyimide resin, phenolic resin, epoxy resin, silicone resin, and urea resin.

[0056] Furthermore, these binder resins may be used individually as homopolymers or copolymers, or as a mixture of two or more types. In addition, known additives such as plasticizers, antioxidants, and ultraviolet absorbers may be used in combination as needed. [Pixel Circuit] The light-emitting device may have a pixel circuit connected to a light-emitting element. The pixel circuit may be an active-matrix type that independently controls the emission of light from a first light-emitting element and a second light-emitting element. The active-matrix type circuit may be voltage-programmed or current-programmed. The drive circuit has a pixel circuit for each pixel. The pixel circuit may have a light-emitting element, a transistor that controls the luminescence brightness of the light-emitting element, a transistor that controls the luminescence timing, a capacitor that holds the gate voltage of the transistor that controls the luminescence brightness, and a transistor for connecting to GND without going through the light-emitting element.

[0057] The light-emitting device has a display area and a peripheral area arranged around the display area. The display area has a pixel circuit, and the peripheral area has a display control circuit. The mobility of the transistors constituting the pixel circuit may be smaller than the mobility of the transistors constituting the display control circuit.

[0058] The slope of the current-voltage characteristics of the transistors constituting the pixel circuit may be smaller than the slope of the current-voltage characteristics of the transistors constituting the display control circuit. The slope of the current-voltage characteristics can be measured using the so-called Vg-Ig characteristic.

[0059] The transistors constituting the pixel circuit are transistors connected to light-emitting elements, such as the first light-emitting element. [Pixel] The organic light-emitting device has a plurality of pixels. Each pixel has sub-pixels that emit light of a different color from the others. The sub-pixels may each have, for example, RGB light-emitting colors.

[0060] A pixel emits light in a region also called the pixel aperture. This region is the same as the first region. The pixel aperture may be 15 μm or less, or 5 μm or more. More specifically, it may be 11 μm, 9.5 μm, 7.4 μm, 6.4 μm, etc.

[0061] The distance between subpixels may be 10 μm or less, specifically 8 μm, 7.4 μm, or 6.4 μm.

[0062] Pixels can take on known arrangements in a plan view. For example, they may be in a stripe arrangement, delta arrangement, pentile arrangement, or Bayer arrangement. The shape of subpixels in a plan view may be any known shape. For example, rectangles, rhombuses, hexagons, etc. Of course, even if it is not a precise shape, if it is close to a rectangle, it is included in the category of rectangles. The shape of subpixels and the pixel arrangement can be used in combination.

[0063] Figure 3(A) is a schematic diagram showing an example of the pixel arrangement and nanostructure arrangement of the image display element in this embodiment. Nanostructures 2000 are arranged according to the light-emitting layer 1000 of each pixel. The range of the nanostructure 2000 corresponding to a pixel may take any shape, such as a circle or a polygon. Furthermore, the range of each nanostructure 2000 may be arranged with space (regions not included in the range of any nanostructure 2000), or they may be arranged so that there are no regions not included in any nanostructure 2000. [Applications of Organic Light-Emitting Devices] Next, a display device according to this embodiment will be described with reference to the drawings.

[0064] Figure 3 is a schematic cross-sectional view showing an example of a display device having an organic light-emitting element and a transistor connected to this organic light-emitting element. The transistor is an example of an active element. The transistor may also be a thin-film transistor (TFT).

[0065] Figure 3(B) shows an example of a pixel, which is a component of the display device according to this embodiment. The pixel has sub-pixels 10. The sub-pixels are divided into 10R, 10G, and 10B based on their light emission. The light emission color may be distinguished by the wavelength emitted from the light-emitting layer, or the light emitted from the sub-pixel may be selectively transmitted or color-converted by a color filter or the like. Each sub-pixel has a reflective electrode 2 which is a first electrode, an insulating layer 3 covering the end of the reflective electrode 2, an organic compound layer 4 covering the first electrode and the insulating layer, a second electrode 5, a protective layer 6, and a color filter 7 on an interlayer insulating layer 1.

[0066] The interlayer insulating layer 1 may have transistors and capacitive elements placed in the layer below or inside it. The transistor and the first electrode may be electrically connected via a contact hole or the like (not shown).

[0067] The insulating layer 3 is also called a bank or pixel separation layer. It covers the edge of the first electrode and is arranged to surround the first electrode. The portion without the insulating layer is in contact with the organic compound layer 4 and becomes the light-emitting region.

[0068] The organic compound layer 4 includes a hole injection layer 41, a hole transport layer 42, a first light-emitting layer 43, a second light-emitting layer 44, and an electron transport layer 45.

[0069] The second electrode 5 may be a transparent electrode, a reflective electrode, or a semi-transparent electrode.

[0070] The protective layer 6 reduces the penetration of moisture into the organic compound layer. Although the protective layer is shown as a single layer, it may consist of multiple layers. Each layer may contain an inorganic compound layer and an organic compound layer.

[0071] The color filters 7 are classified into 7R, 7G, and 7B according to their color. The color filters may be formed on a planarization film (not shown). The color filters may also have a resin protective layer (not shown). Alternatively, the color filters may be formed on a protective layer 6, or they may be bonded together after being placed on an opposing substrate such as a glass substrate.

[0072] The display device 100 in Figure 3(C) shows an organic light-emitting element 26 and a TFT 18 as an example of a transistor. A substrate 11 made of glass, silicon, or the like is provided, with an insulating layer 12 on top of it. An active element 18 such as a TFT is placed on the insulating layer, and the gate electrode 13, gate insulating film 14, and semiconductor layer 15 of the active element are arranged therein. The TFT 18 is also composed of a semiconductor layer 15, a drain electrode 16, and a source electrode 17. An insulating film 19 is provided on top of the TFT 18. The anode 21 and the source electrode 17 that constitute the organic light-emitting element 26 are connected via a contact hole 20 provided in the insulating film.

[0073] The method of electrical connection between the electrodes (anode, cathode) included in the organic light-emitting element 26 and the electrodes (source electrode, drain electrode) included in the TFT is not limited to the configuration shown in Figure 3(B). In other words, it is sufficient for either the anode or cathode to be electrically connected to either the TFT source electrode or the drain electrode. TFT refers to a thin-film transistor.

[0074] In the display device 100 shown in Figure 3(C), the organic compound layer is depicted as a single layer, but the organic compound layer 22 may consist of multiple layers. A first protective layer 24 and a second protective layer 25 are provided on the cathode 23 to reduce the degradation of the organic light-emitting element.

[0075] In the display device 100 shown in Figure 3(C), a transistor is used as the switching element, but other switching elements may be used instead.

[0076] Furthermore, the transistor used in the display device 100 in Figure 3(C) is not limited to a transistor using a single-crystal silicon wafer, but may also be a thin-film transistor having an active layer on an insulating surface of the substrate. Examples of the active layer include non-single-crystal silicon such as single-crystal silicon, amorphous silicon, and microcrystalline silicon, and non-single-crystal oxide semiconductors such as indium zinc oxide and indium gallium zinc oxide. Thin-film transistors are also called TFT elements.

[0077] The transistors included in the display device 100 in Figure 3(C) may be formed within a substrate such as a Si substrate. Here, "formed within a substrate" means that the transistors are manufactured by processing the substrate itself, such as a Si substrate. In other words, having transistors within a substrate can be seen as the substrate and transistors being formed as a single unit.

[0078] The organic light-emitting element according to this embodiment has its luminescence controlled by a TFT, which is an example of a switching element, and by providing multiple organic light-emitting elements on the surface, an image can be displayed according to the luminescence of each element. The switching element according to this embodiment is not limited to a TFT, but may also be a transistor made of low-temperature polysilicon, or an active matrix driver formed on a substrate such as a Si substrate. "On the substrate" can also mean "within the substrate." Whether to provide a transistor within the substrate or to use a TFT is selected depending on the size of the display area; for example, if the size is about 0.5 inches, it is preferable to provide the organic light-emitting element on a Si substrate.

[0079] Figure 4 is a schematic diagram of an HMD (head-mounted display) 2301 as a display device according to this embodiment. Figure 4(A) is a schematic diagram showing a head-mounted display and an observer wearing it. The HMD 2301 is worn on the observer's head. Reference numeral 2302 indicates the observer's right eye, and reference numeral 2303 indicates the observer's left eye. Display lenses 2304 and 2305 constitute the right eye eyepiece optical system OR1, and display lenses 2306 and 2307 constitute the left eye eyepiece optical system OL1. Each eyepiece optical system is a coaxial optical system composed of a plurality (two) of display lenses. The observer's right eye 2302 is positioned in the exit pupil ER1 of the right eye eyepiece optical system OR1, and the observer's left eye 2303 is positioned in the exit pupil EL1 of the left eye eyepiece optical system OL1. The exit pupil ER1 is located at a distance E1 from the right eye eyepiece optical system OR1. Similarly, the exit pupil EL1 is located at a distance E1 from the left eyepiece optical system OL1. Optical films 2314 for lens protection and light focusing are provided on the surface of the right eyepiece optical system OR1 (the surface on the right eye 2302 side) and the surface of the left eyepiece optical system OL1 (the surface on the left eye 2303 side).

[0080] Reference numerals 2308 and 2309 indicate display devices for the right eye and left eye, respectively. These display devices may be the display devices according to Embodiment 1. Figure 4(B) is a schematic diagram showing an example in which the display device according to this embodiment is connected to an external device, and shows the appearance of the HMD 2301 and the personal computer 2350 connected thereto. Each display device displays a display image (original image) corresponding to the image signal output from the personal computer 2350. In this configuration, the connection is wired, but it may also be wireless. Furthermore, the HMD 2301 may be a standalone device with an image processing device built inside.

[0081] The right eyepiece optical system OR1 and the left eyepiece optical system OL1 guide light from the display devices 2308 and 2309 to the exit pupils ER1 and EL1, respectively, projecting an enlarged virtual image of the displayed image onto the observer's right eye 2302 and left eye 2303. This allows the observer to view the displayed image (or virtual image) shown on the display devices 2308 and 2309 through the right eyepiece optical system OR1 and the left eyepiece optical system OL1.

[0082] Although not shown in the diagram, the HMD2301 may have a control device. The control device functions as a power supply that provides power to the display devices 2308 and 2309, and also controls the operation of the display devices 2308 and 2309.

[0083] While preferred embodiments of the present disclosure have been described above, the present disclosure is not limited to these embodiments, and various modifications and changes are possible within the scope of its essence.

[0084] This application claims priority based on Japanese Patent Application No. 2025-051440, filed on March 26, 2025, and all of its contents are incorporated herein by reference.

Claims

1. An image display element comprising a pixel and a nanostructure disposed on the pixel, wherein the nanostructure imparts a phase difference distribution to the light from the light-emitting layer, centered on a first center different from the center of the light-emitting layer of the pixel in the radial direction of the nanostructure, and the first center is arranged along the circumferential direction of the nanostructure.

2. The image display element according to claim 1, characterized in that the distance between the first center and the center of the light-emitting layer is shorter than the radial length of the light-emitting layer.

3. The image display element according to claim 2, characterized in that, when ΔY is the distance between the first center and the center of the light-emitting layer, and Y is the radial length of the light-emitting layer, the condition 0.10 < ΔY / Y < 0.90 is satisfied.

4. The image display element according to claim 1, characterized in that the nanostructure imparts a phase difference distribution to the light from the light-emitting layer, centered on a second center different from the first center in the radial direction.

5. The image display element according to claim 4, characterized in that the distance between the first center and the center of the light-emitting layer is longer than twice the radial length of the light-emitting layer.

6. The image display element according to claim 5, characterized in that, when ΔY is the distance between the first center and the center of the light-emitting layer, and Y is the radial length of the light-emitting layer, the condition 2.10 < ΔY / Y < 5.00 is satisfied.

7. The image display element according to any one of claims 1 to 6, characterized in that the nanostructure includes a plurality of unit structures.

8. An image display device comprising an image display element according to any one of claims 1 to 7 and an optical system.

Images