Display apparatus and system having the same

Abstract

A display device is disclosed. The disclosed display device comprises at least one virtual object image source, at least one display device for displaying the virtual object image, and at least one variable lens, wherein the at least one variable lens comprises at least two variable optical cells.

Description

Technology Field

[0001] An exemplary embodiment relates to an augmented reality or virtual reality (AR,VR) system, and more specifically, to a display device including a variable lens that adjusts the image focus in a display device of an augmented reality or virtual reality (AR,VR) system according to the position of a virtual image, the position of the eye, and the position of an object, and a system including the same. Background Technology

[0002] In augmented reality or virtual reality (AR, VR) systems, it is important to develop devices that display virtual images for users, particularly augmented reality images superimposed on real-world images. From the user's perspective, image display in AR and VR systems requires realistic depth perception of virtual reality images, high visual acuity (especially for users with refractive errors), and the ability to provide relatively high performance with the minimum size of the display device. On the other hand, from the perspective of AR and VR system developers, display devices require a wide range of optical power adjustment (minimum -4 diopters to +4 diopters), small adjustment steps (e.g., 0.25 diopters), and a small form factor for application in systems, such as headsets, head-mounted devices, or smart glasses. One of the existing problems is the vergence-accommodation conflict, which causes user eye strain. Most AR and VR headsets have a fixed focal length and cannot transform virtual images within this focal length. As a result, the eye's vergence and the distance at which the user's eyes focus during accommodation do not lie in a single plane. This can cause eye fatigue, headaches, and nausea in users. When virtual objects at a fixed focal distance as well as real objects located at different distances are observed simultaneously through an AR device, so-called convergent accommodation mismatch (VAC) occurs. In this case, when the eye focuses on an object, it can focus on either the virtual object or an observable object in the real external world, but it cannot focus on both objects simultaneously. In the case of VR, VAC conflict occurs when the focal plane (the eye's accommodation from the display) does not align with the relative size of the object (the eye's convergence axis from the object). The problem to be solved

[0003] An exemplary embodiment provides a display device capable of varying the focal length and a system including the same. means of solving the problem

[0004] A display device according to an exemplary embodiment includes at least one virtual object image source; and at least one variable lens; wherein the at least one variable lens includes at least two variable optical cells, and each of the at least two variable optical cells includes an electrode pattern for adjusting the focal length of the at least one variable lens, and the electrode pattern may be configured so that the optical power of the at least one variable lens changes to an equidistant dioptic step.

[0005] The above equidistant diopter step Δ may be 0.25 diopters.

[0006] The above at least two variable optical cells may include a first variable optical cell having a first electrode, a second electrode and a first liquid crystal layer between the first electrode and the second electrode, and a second variable optical cell having a third electrode, a fourth electrode and a second liquid crystal layer between the third electrode and the fourth electrode.

[0007] The above at least one variable lens includes a first variable lens and a second variable lens, and further includes a light guide plate that transmits light from the virtual object image source, and the light guide plate may be disposed between the first variable lens and the second variable lens.

[0008] The first variable lens can be configured to be positioned in front of the user's eyes.

[0009] The display device further includes a light guide plate that transmits light from the virtual object image source, and the at least one variable lens may include a first variable lens disposed between the virtual object image source and the light guide plate, and a second variable lens disposed outside of the light guide plate.

[0010] The above electrode pattern may include concentric ring electrodes and a circular electrode positioned at the center of the concentric ring electrodes.

[0011] The above electrode pattern may include parallel strip electrodes arranged in a horizontal or vertical direction.

[0012] The above at least one variable lens may include a first variable lens having a first optical power and a second variable lens having a second optical power that is equal in magnitude to the first optical power but opposite in sign.

[0013] The above at least one variable lens may include a first variable lens having a first optical power and a second optical power for correcting a user's refraction error, and a second variable lens having a third optical power that is equal in magnitude to the first optical power but opposite in sign.

[0014] At least one variable lens may include a first variable lens having a first optical power and a second optical power for correcting a user's refraction error, and a second variable lens having a third optical power equal to the second optical power.

[0015] The above at least two variable optical cells may include a polarization-dependent electrode pattern.

[0016] The above at least two variable optical cells may include polarization-independent electrode patterns.

[0017] The above at least one variable lens may be circular.

[0018] The above at least one variable lens may have a rectangular shape or a polygonal shape.

[0019] The above at least one variable lens may be configured to have optical power for correcting the user's refractive error.

[0020] The above at least one variable lens can be configured to have zero optical power.

[0021] The above at least one variable lens may be configured to have a total optical power in the range of (-4) to (+4) diopters.

[0022] The above display device can be applied to an augmented reality (AR) system.

[0023] The above display device can be applied to a virtual reality (VR) system. Effects of the invention

[0024] A display device according to an exemplary embodiment can adjust optical power in equidistant dioptric steps by at least one variable lens. By doing so, a wide range of total optical power can be provided.

[0025] A system including a display device according to an exemplary embodiment can be applied to an AR system or a VR system and can reduce eye strain for the user. Brief explanation of the drawing

[0026] The drawings are provided herein to aid in understanding the essence of the invention. The drawings are schematic and are not drawn to scale. The drawings are for illustrative purposes only and are not intended to limit the scope of the invention. FIG. 1 schematically illustrates a display device according to an exemplary embodiment. FIG. 2 illustrates an example of a variable lens of a display device according to an exemplary embodiment. FIG. 3 illustrates a ring electrode pattern of a display device according to an exemplary embodiment. FIG. 4 illustrates examples of variable lenses of a display device according to an exemplary embodiment. FIG. 5 illustrates an example of a variable lens of a display device according to an exemplary embodiment. Figure 6 illustrates a modified example of the display device shown in Figure 1. Figure 7 illustrates a modified example of the display device shown in Figure 1. FIG. 8 schematically illustrates a display device according to another exemplary embodiment. Figure 9 illustrates a modified example of the display device shown in Figure 8. FIG. 10 illustrates a modified example of the display device shown in FIG. 8. FIG. 11 shows an equidistant diopteric step of a display device according to an exemplary embodiment. FIG. 12 shows an equidistant diopteric step of a display device according to another exemplary embodiment. FIG. 13 schematically illustrates a display device according to another exemplary embodiment. FIG. 14 is a diagram illustrating the operation of a variable optical cell having a strip electrode pattern of a display device according to an exemplary embodiment. FIG. 15 is a diagram illustrating the operation of a variable optical cell having a strip electrode pattern of a display device according to an exemplary embodiment. FIG. 16 is a diagram illustrating the operation of a variable optical cell having a concentric ring electrode pattern of a display device according to an exemplary embodiment. FIG. 17 is a diagram illustrating the operation of a variable optical cell having a concentric ring electrode pattern of a display device according to an exemplary embodiment. FIG. 18 illustrates an example in which four variable optical cells having a strip electrode pattern are provided in a display device according to an exemplary embodiment. FIG. 19 illustrates an example in which two variable optical cells having a concentric ring electrode pattern are provided in a display device according to an exemplary embodiment. Specific details for implementing the invention

[0027] Hereinafter, a display device according to various embodiments and a system including the same will be described in detail with reference to the attached drawings. In the following drawings, the same reference numerals refer to the same components, and the size of each component in the drawings may be exaggerated for clarity and convenience of explanation. Terms such as "first," "second," etc., may be used to describe various components, but the components should not be limited by these terms. The terms are used solely for the purpose of distinguishing one component from another.

[0028] A singular expression includes a plural expression unless the context clearly indicates otherwise. Furthermore, when a part is described as "comprising" a certain component, this means that, unless specifically stated otherwise, it does not exclude other components but may include additional components. Additionally, the size or thickness of each component in the drawings may be exaggerated for clarity of explanation. Furthermore, when a specific material layer is described as existing on a substrate or another layer, that material layer may exist in direct contact with the substrate or other layer, or a third layer may exist between them. Also, since the materials constituting each layer in the following examples are exemplary, other materials may be used.

[0029] Additionally, terms such as “...part,” “module,” etc., as described in the specification refer to a unit that processes at least one function or operation, and this may be implemented in hardware or software, or as a combination of hardware and software.

[0030] The specific embodiments described in this embodiment are examples and do not limit the technical scope in any way. For the sake of brevity of the specification, descriptions of conventional electronic configurations, control systems, software, and other functional aspects of said systems may be omitted. Additionally, the connections of lines or connecting members between components shown in the drawings are illustrative of functional connections and / or physical or circuit connections, and may be replaced or additionally represented as various functional connections, physical connections, or circuit connections in the actual device.

[0031] The use of the term “above” and similar descriptive terms may apply to both the singular and plural forms.

[0032] Unless there is an explicit statement that the steps constituting the method must be performed in the described order, they may be performed in a suitable order. Furthermore, the use of all exemplary terms (e.g., etc.) is merely intended to describe the technical concept in detail and, unless limited by the claims, such terms do not limit the scope of the rights.

[0033] FIG. 1 schematically illustrates a display device according to an exemplary embodiment. The display device (100) may include at least two variable lenses for each of the user's eyes (E). For example, the display device (100) may include a first variable lens (LC1) and a second variable lens (LC2) for each of the user's eyes (E). The display device (100) may include a virtual object image source (110) and a light guide plate (120) that transmits light from the virtual object image source (110). The virtual object image source (110) may include, for example, a liquid crystal display, an OLED display, an LED display, etc.

[0034] A virtual object image source (110) may be located at one end of a light guide plate (120). A first and second variable lens (LC1) (LC2) may be located at the other end of the light guide plate (120). Optical radiation forming a virtual object image may be transmitted from the virtual object image source (110) to the first variable lens (LC1) along the light guide plate (120).

[0035] As can be seen in FIG. 1, light output from the light guide plate (120) can be transmitted to the user's eye (E) through the first variable lens (LC1). The first variable lens (LC1) can move the virtual object image along the optical axis and eliminate the convergence-accommodation conflict of the eye.

[0036] The second variable lens (LC2) is configured to compensate for the optical power induced by the first variable lens (LC1), allowing the user to observe objects in the external (real) world without interference and distortion, as if looking directly at the external world without a headset. This allows the user to feel as if they are looking at the external world with their naked eye without an AR system. At least one variable lens can be combined with a virtual object image source through a light guide plate (120). One end of the light guide plate (120) can be combined with a virtual object image source (110) and can generate a virtual object image having optical power of D0 = 0 (parallel beam) through at least one variable lens.

[0037] The other end of the light guide plate (120) may be positioned between the first and second variable lenses (LC1) (LC2). Optical radiation forming a virtual object image transmitted by the light guide plate (120) is reflected from the inner surface of the light guide plate (120) by internal total reflection and enters the user's eye (E) through the first variable lens (LC1).

[0038] At least one variable lens may each include at least two variable optical cells. At least one variable lens may have a stacked structure in which at least two variable optical cells are stacked. FIG. 2 illustrates an example of a variable optical cell.

[0039] Referring to FIG. 2, at least two variable optical cells (130) may include, for example, a first variable optical cell (131) and a second variable optical cell (141). The first variable optical cell (131) may include a first electrode (133), a second electrode (135), and a first liquid crystal layer (134) between the first electrode (133) and the second electrode (135). The first electrode (133) may be provided on a first substrate (132). The second electrode (135) may be provided on a second substrate (136). The first substrate (132) and the second substrate (136) may be, for example, transparent substrates. The first electrode (133) may be provided as pixel electrodes spaced apart from each other, and the second electrode (135) may be provided as a common electrode. Voltage may be applied independently through the first electrode (133). That is, the first electrode (133) may be an addressable electrode. The positions of the first electrode (133) and the second electrode (135) may be interchangeable.

[0040] The second variable optical cell (141) may include a third electrode (137), a fourth electrode (139), and a second liquid crystal layer (138) between the third electrode (137) and the fourth electrode (139). The third electrode (137) may be provided on the second substrate (136), and the fourth electrode (139) may be provided on the third substrate (140). The second substrate (136) may be used in common for the second electrode (135) and the third electrode (137). That is, the second electrode (135) may be provided on one side of the substrate (136), and the third electrode (137) may be provided on the other side of the substrate (136). However, it is not limited thereto, and it is also possible to provide a substrate for each of the second electrode (135) and the third electrode (137).

[0041] The third electrode (137) may be provided as a common electrode, and the fourth electrode (139) may be provided as pixel electrodes spaced apart from each other. Voltage may be applied independently through the fourth electrode (139). That is, the fourth electrode (139) may be an addressable electrode. The positions of the third electrode (137) and the fourth electrode (139) may be interchangeable. The second substrate (136) may include an insulating material.

[0042] Referring to FIG. 3, the first electrode (133) and the fourth electrode (139) may each include an electrode pattern arranged spaced apart from each other. For example, the first electrode (133) and the fourth electrode (139) may have a concentric ring electrode pattern. However, the structure of the electrode pattern is not limited thereto and can be changed in various ways, such as a parallel strip electrode pattern. This will be described later.

[0043] The first electrode (133) and the fourth electrode (139) may include, for example, a plurality of Fresnel regions (150). Each of the plurality of Fresnel regions (150) may include at least one electrode (151). Each of the plurality of Fresnel regions (150) may be provided with a different number of electrodes (151). Additionally, the first electrode (133) and the fourth electrode (139) may each be provided with a different number of Fresnel regions. The focal length of the variable lens can be adjusted by controlling the number of Fresnel regions, the number of electrodes, the electrode pattern, etc.

[0044] Meanwhile, the first and second variable lenses (LC1) (LC2) may have various cross-sectional shapes, such as a square cross-sectional shape (Fig. 4a), a circular cross-sectional shape (Fig. 4b), and a pentagonal cross-sectional shape (Fig. 4c), as shown in FIG. 4. The first and second variable lenses (LC1) (LC2) are not limited to these and may have various shapes, such as polygons and curves.

[0045] Although FIG. 2 illustrates an example in which a variable lens includes two variable optical cells, as shown in FIG. 5, the variable lens includes first to nth variable optical cells (1, 2, ..., n) and the first to nth variable optical cells (1, 2, ..., n) can be stacked. If the number of variable optical cells is large, the range of optical power may increase, but the volume of the entire system may increase, so the number of variable optical cells can be adjusted as needed.

[0046] Lens aperture and optical power range are key parameters of display devices in augmented reality (AR) and virtual reality (VR) systems. AR and VR systems require a large aperture to provide a realistic perception of the depth of field of virtual object images. However, in the case of variable lenses with a large aperture, the lens radius (r) increases, and since the achievable optical power decreases as the lens radius (r) increases, the range of optical power (D) may be limited.

[0047] The maximum number of electrodes (Nmax) for the optical power (D) of the variable lens is as follows.

[0048] <Equation 1>

[0049] Here, Nmax represents the maximum number of addressable electrodes per Fresnel region for a variable lens having optical power (D), lens radius (r), and wavelength (λ). In a variable optical cell, addressable electrodes are arranged, and for a period including the electrode sizes and the distances between electrodes, (△R) represents a technical limit equal to the sum of the minimum width of the technically possible electrodes and the minimum distance between the technically possible electrodes. Here, the sum of the width of the last electrode and the distance from the last electrode to the previous electrode has a value greater than or equal to the technical limit (△R).

[0050] According to an exemplary embodiment, a display device for an augmented reality or virtual reality (AR, VR) system includes at least one variable lens, and each of the at least one variable lens may include at least two variable optical cells. The at least two variable optical cells include an electrode pattern configured to adjust the focal length of the variable lens, so that the optical power of the variable lens can be adjusted to change in equidistant dioptric steps (△).

[0051] An exemplary embodiment can provide a wide range of optical power, for example, a range of (-4) diopters to (+4) diopters, and a large aperture of the lens, for example, at least 20 mm. This can be realized by a combination of multiple variable optical cells and the respective interrelated electrode patterns and the number of electrodes.

[0052] According to an exemplary embodiment, the optical power range is selected to be from (-Dmax) to (Dmax), and this can be provided to a display device having an equidistant dioptic stage (△) by using a lens having a lens radius (r) and a technical limitation (△R) of the electrode array period.

[0053] Meanwhile, minimum diffraction efficiency ( ) can be selected according to the actual requirements of the optical system. Based on the selected diffraction efficiency, the number of phase levels (L) per Fresnel region for the variable lens is calculated by the following equation.

[0054] <Equation 2>

[0055] According to an exemplary embodiment, the equidistant dioptric step (△) may be provided as follows: A first variable optical cell (131) having minimum optical power is selected, and a system inequality This is resolved, and accordingly, a value (k1) can be obtained. N1 represents the minimum number of electrodes. The maximum optical power of the first variable optical cell (131) is calculated by the value (k1), where k1 is a variable of optical power. k1 indicates how many times greater the maximum optical power is than the minimum optical power for a given lens. L is the number of phase levels per Fresnel region for a given lens. A is a constant calculated by the following formula.

[0056] <Equation 3>

[0057] Using the obtained value (k1), the minimum number of electrodes (N1) can be obtained for the first variable optical cell (131). Accordingly, the electrode structure of the first variable optical cell (131) can be determined according to the presented calculation of the minimum and maximum optical power for the first variable optical cell (131) and the minimum number of electrodes required to provide these optical powers.

[0058] Next, minimum optical power A second variable optical cell (141) having is selected, and a system inequality This is resolved, and a maximum value for the value (k2) can be obtained. Along with this, the maximum optical power for the second variable optical cell (141) This can be obtained. For the obtained value k2, the minimum number of electrodes (N2) per one Fresnel region of the second variable optical cell (141) is determined, where N2 can be determined by the values ​​N1, L, and Δ.

[0059] If a solution to the aforementioned system inequality for the second variable optical cell (141) cannot be found, this means that more variable optical cells are required. And, in addition to the aforementioned first and second variable optical cells (131)(141), minimum optical power A third variable optical cell having may be further provided. An example in which three or more variable optical cells are provided is illustrated in FIG. 5.

[0060] For the third variable optical cell, the solution to the following system inequality can be found.

[0061]

[0062] The maximum value for k2 is obtained, and together with this, the maximum optical power for the second variable optical cell is obtained, and then the maximum value for k3 and the maximum optical power for the third variable optical cell are obtained. A value can be obtained. Using the obtained values ​​k2 and k3, a minimum number of electrodes (N2) per Fresnel region for the second variable optical cell can be obtained, and then a minimum number of electrodes (N3) per Fresnel region for the third variable optical cell can be obtained.

[0063] According to an exemplary embodiment, the number of variable lenses, each comprising at least two variable optical cells, may be selected according to a specific embodiment of the display device according to the exemplary embodiment in an augmented reality (AR) system or a virtual reality (VR) system. For example, at least one variable lens may be provided for implementation in an AR / VR system. The number of variable lenses in the display device does not necessarily depend on the absence or presence of the need for vision correction, because the optical power of the lens that moves the virtual image may change according to the amount of refractive error according to the user's vision.

[0064] Accordingly, according to exemplary embodiments, the need for additional lenses designed for vision correction can be eliminated. Nevertheless, in some embodiments, variable lenses designed to correct the user's vision may be used, but it should be understood that the scope of the invention is not limited to these embodiments and generally does not need to be. In other words, it is not necessary to use separate variable lenses for the user's vision correction. The following embodiments having one or two variable lenses applied to an AR or VR system will be considered.

[0065] A display device according to an exemplary embodiment may include one or more variable lenses. Each variable lens may include at least two variable optical cells. In the embodiment, the number of variable optical cells for each of the at least one variable lens and the number of electrodes of the variable optical cells may be determined by technical limitations such as the required optical power range, the required equidistant dioptric step, the required diffraction efficiency, and the minimum period of the electrodes that are technically possible.

[0066] As mentioned above, the number of variable lenses in a display device according to an exemplary embodiment may be determined by whether the display device is used in an AR system or a VR system, and whether the user's vision is normal or requires correction, etc. In a display device applied to a VR system, at least one variable lens comprising at least two variable optical cells may be provided. The variable lens may be designed to transform a virtual object image according to a required optical power range and a required equidistant diopteric step (i.e., required for VAC problem solving).

[0067] When the user's vision correction is required (i.e., when the user's vision deviates from normal), the display device of the AR system may be equipped with two or more variable lenses, each containing at least two variable optical cells. On the other hand, when the user's vision correction is required (i.e., when the user's vision deviates from normal), the display device of the VR system may be equipped with at least one variable lens, each containing at least two variable optical cells. That is, in this case, it is also possible to provide only one variable lens.

[0068] A variable lens can serve to convert a virtual object image into the required optical power range and the required equidistant dioptric step (i.e., VAC problem solving). However, unlike in the case of a user's normal vision, the value of the optical power of at least one variable lens used can be adjusted by the value of the refractive error according to the user's vision.

[0069] An example of a change in a variable lens combined with a virtual object image source (110) by a light guide plate (120) is shown in FIG. 6.

[0070] Referring to FIG. 6, the display device (100) may include a first variable lens (LC1) and a second variable lens (LC2). The first variable lens (LC1) can convert a virtual object image into a plane identical to the focal plane where a real object in the external world is located (solving the VAC problem). The second variable lens (LC2) can adjust the focal length of a real object image received from the external world. This allows the user to observe the external world through the AR system with the same clarity and sharpness as the virtual object image. In this case, the optical power of the second variable lens (LC2) may be configured to have the same magnitude as the optical power of the first variable lens (LC1) but with the opposite sign. That is, the first variable lens (LC1) may have an optical power of (Dvirt), and the second variable lens (LC2) may have an optical power of (-Dvirt).

[0071] In this case, two or more variable lenses in the AR system may each include two or more variable optical cells. For example, the first variable lens (LC1) and the second variable lens (LC2) may each include two or more variable optical cells. Thus, each variable lens can independently adjust its focal length (optical power) within the required range and under given limitations.

[0072] According to the embodiment illustrated in FIG. 6, the first variable lens (LC1) and the second variable lens (LC2) may have optical power (-Dvirt + Dvirt = 0) of the same size but opposite sign. Thus, the virtual object image can move by a focal length corresponding to the optical power of the first variable lens (LC1). Meanwhile, since the total optical power (-Dvirt + Dvirt = 0) of the image of the external world is 0, it can be perceived by the user's eyes as if there were no AR device mounted on the head. In this embodiment, correction of refractive errors of the user's eyes is not provided.

[0073] In the embodiment illustrated in FIG. 7, correction of the user's refractive error, that is, correction of the user's vision so that the user can observe a clear and sharp virtual object image and a real object, may be provided. In this embodiment, the first variable lens (LC1) may have a first optical power (Dvirt) and a second optical power (Derr_eye). The first optical power (Dvirt) can transform the virtual object image by the required focal length, and the second optical power (Derr_eye) can correct the user's refractive error.

[0074] The second variable lens (LC2) may have a third optical power (-Dvirt) that is equal in magnitude to the first optical power (Dvirt) but has the opposite sign. As a result, the virtual object image is moved by the first variable lens (LC1) by a focal length corresponding to the total optical power (Dvirt + Derr_eye), which is the sum of the first optical power (virt) and the second optical power (Derr + Derr_eye), so that the virtual object image can be viewed without optical refraction error. In addition, regarding the actual object image, the user can view the actual object image clearly because the optical power is adjusted to (-Dvirt + Dvirt + Derr_eye) by the first variable lens (LC1) and the second variable lens (LC2) to account for optical refraction error. In other words, the optical power corresponding to the focal length of the image from the outside world consists only of the optical power (Derr_eye) required to correct the user's refraction error, so the user can view the image from the outside world clearly.

[0075] FIG. 8 schematically illustrates a display device according to another exemplary embodiment.

[0076] The display device (200) may be applied to an augmented reality system or a virtual reality system. The display device (200) may include at least one variable lens for each of the user's eyes (E).

[0077] The display device (200) may include, for example, a first variable lens (LC1) and a second variable lens (LC2). The display device (200) may include a virtual object image source (210) and a light guide plate (220) that transmits light from the virtual object image source (210).

[0078] A virtual object image source (210) may be provided at one end of the light guide plate (220). A first variable lens (LC1) may be located between one end of the light guide plate (220) and the virtual object image source (210). A second variable lens (LC2) may be located at the other end of the light guide plate (220). A second variable lens (LC2) may be located at the outer end of the light guide plate (220). Here, the outer end of the light guide plate (220) may represent the side far from the human eye (E).

[0079] The first variable lens (LC1) and the second variable lens (LC2) may each include at least two variable optical cells. The at least two variable optical cells may include, for example, a first variable optical cell and a second variable optical cell, and since the first and second variable optical cells are the same as those shown in FIGS. 2 and 3, a detailed description is omitted here.

[0080] The light radiation passing through the first variable lens (LC1) can be transmitted through the light guide plate (220). The light radiation is transmitted through total internal reflection of the light guide plate (220) and enters the user's eye (E).

[0081] FIG. 9 is intended to explain the operation of a display device (200) according to the embodiment illustrated in FIG. 8.

[0082] The first variable lens (LC1) may have a first optical power (Dvirt) required to transform a virtual object image by the required focal length. Meanwhile, in this embodiment, a second variable lens (LC2) may be optionally provided. That is, it is possible to remove the second variable lens (LC2). Alternatively, the power of the variable optical cell of the second variable lens (LC2) may be turned off to make the optical power zero. Therefore, in this exemplary embodiment, when the user has normal vision, it is possible to provide only one variable lens because the first variable lens (LC1) can be prevented from being directly positioned toward the user's eye (E) by the light guide plate (220) in order to apply this embodiment to an AR system.

[0083] In this embodiment, the first variable lens (LC1) can be positioned out of reach of the user's eyes. For example, as shown in FIG. 9, the first variable lens (LC1) can be positioned between the virtual object image source (210) and the light guide plate (220). Consequently, in this embodiment, the virtual object image is moved by a focal length corresponding to the optical power of the first variable lens (LC1), and regarding the external object image, the image from the outside world can be viewed with the naked eye as if there were no head-mounted device. This is because the second variable lens (LC2) is absent or the power of the variable optical cell of the second variable lens (LC2) is turned off, that is, the optical power of the second variable lens (LC2) is zero.

[0084] FIG. 10 is illustrated to explain the operation of the embodiment of FIG. 8 when the correction of the user's eye refraction error is performed.

[0085] In this embodiment, the first variable lens (LC1) may have a first optical power (Dvirt) and a second optical power (Derr_eye). The first optical power (Dvirt) corresponds to the optical power required to convert a virtual object image by the required focal length, and the second optical power (Derr_eye) corresponds to the optical power required to correct the refractive error of the user's eye. The second variable lens (LC2) may have a third optical power (Derr_eye) required to correct the refractive error of the user's eye.

[0086] As a result, the virtual object image is moved by a focal length corresponding to the total optical power (Dvirt + Derr_eye), which is the sum of the first optical power (Dvirt) and the second optical power (Deye). At this time, since the optical power is adjusted taking into account the refractive error of the eye, the user can see the virtual object image clearly.

[0087] Since the third optical power (Derr_eye), which corresponds to the focal length of the image from the external world, consists only of the optical power necessary to correct the refractive error of the user's eye, the user can clearly see the image from the external world without refractive error.

[0088] According to an exemplary embodiment, a display device for an augmented reality (AR) or virtual reality (VR) system may provide an equidistant optical power step (△) (or an equidistant dioptic step). The number of equidistant dioptic steps (△) and phase levels (L) may determine the number of electrodes (N1) for the first variable optical cell (131). N1 may determine the radius and width of the electrode pattern, etc.

[0089] The electrode pattern (their radius and width) of the second variable optical cell (141) can be determined by a value N2 equal to the minimum number of electrodes required to ensure the maximum optical power of the second variable optical cell (141) under given limits. The value N2 can be obtained from the value N1 of the first variable optical cell (131). This indicates that the electrode pattern of the second variable optical cell (141) can be determined by the electrode pattern of the first variable optical cell (131) under given limits and requirements for the optical system.

[0090] In an exemplary embodiment, the electrodes of each variable optical cell may have a ring shape and be arranged concentrically. Refer to FIG. 3 for an electrode pattern with a concentric structure. The concentric electrode pattern may include a first electrode to an nth electrode. The first electrode may have a circular shape and be located at the center of the electrode pattern. However, the electrode pattern is not limited thereto, and various shapes are possible, such as a parallel strip shape or a polygonal array. Additionally, an electrode pattern with an irregular shape may be used.

[0091] A variable lens including at least two variable optical cells may have a rectangular, circular, or any other suitable aperture shape depending on the shape of the electrode pattern. The shape of the lens aperture may vary, such as circular, rectangular, or polygonal (see FIG. 4).

[0092] The lens aperture can be linked to the type of variable lens, such as actual requirements for the system, size limitations, and requirements regarding the shape and size of the electrodes. For example, to form a spherical variable lens where the transmitted light does not depend on the incident light polarization, four variable optical cells with strip-shaped parallel electrodes may be provided. In this way, light with x-direction polarization and y-direction polarization can be focused. Additionally, to focus light with both x-direction polarization and y-direction polarization, two variable optical cells with concentric ring electrodes may be provided to achieve the same result as when four variable optical cells with strip-shaped parallel electrodes are provided.

[0093] Depending on different factors, one or more different embodiments of the variable optical cell may be preferred within the scope of legal protection of the present invention. For example, the variable optical cell may be controlled by the need to reduce the thickness of the optical system (in this case, a ring electrode is selected) or the simplicity of electrode manufacturing (in this case, a strip electrode is selected), etc.

[0094] Electrode patterns including concentric ring electrodes will be considered below as non-limiting examples, and those skilled in the art will understand that electrode patterns may also be implemented in other configurations explicitly listed herein.

[0095] In one example, the variable optical cell may include, for example, an aperture diameter of 20 mm and a concentric ring electrode pattern. Referring to FIGS. 2 and 3, the first variable optical cell (131) may include, for example, 24 Fresnel regions (150). The electrodes of each Fresnel region (150) may have a predetermined width and a gap (distance designated as g) between adjacent electrodes. The second variable optical cell (141) may include, for example, 96 Fresnel regions (150). In this case, the first variable optical cell (131) may provide optical power in the range of 0.25 diopters to 1 diopter (for the variable optical cell having 24 Fresnel regions). And, the second variable optical cell (141) may provide optical power in the range of 1 diopter to 3 diopters (for the variable optical cell having 96 Fresnel regions). And, the total optical power range by the first and second variable optical cells (131)(141) may be 0 to 4 diopters.

[0096] Two variable optical cells can provide an equidistant dioptric step (Δ) within the total optical power range provided by them.

[0097] FIG. 11 shows that the focal length is varied with an equidistant dioptic step (Δ) by a first variable lens (LC1) and a second variable lens (LC2). For example, an exemplary display device may provide an equidistant dioptic step of 0.25 D. Thus, it may provide optical power of 0, 0.25 D, 0.5 D, ..., 4 D. However, the equidistant dioptic step is not limited thereto.

[0098] FIG. 12 illustrates an example of compensating for refractive errors to correct a user's vision. An equidistant dioptric step of (-0.25)D can be provided by the first variable lens (LC1) and the second variable lens (LC2). Thus, optical power of (-0.25 D), (-0.5 D), ..., (-4D) can be provided.

[0099] According to an exemplary embodiment, a first variable lens can be used to convert a virtual object image into the field of view of an AR / VR system while maintaining the user's ability to observe the real world. The first variable lens (LC1) can convert the virtual object image into the field of view of an AR / VR system while simultaneously maintaining the user's ability to observe the external real world (in the case of an AR system). Additionally, a second variable lens (LC2) can be used without positional correction of the image received from the external real world. As a result, the user can view a clear image of the real world and the virtual object image transmitted within the user's field of view within the same focal point (see FIG. 1, 6, 7).

[0100] In another embodiment, a first variable lens (LC1) may be positioned between a virtual object image source (210) and a light guide plate (220). A light beam propagates from the virtual object image source through the first variable lens (LC1) and is transmitted to the user's eye through the light guide plate (220). A second variable lens (LC2) is positioned on the opposite side of the light guide plate (220) from the user's field of vision (see FIG. 8, 9, 10).

[0101] However, using a light guide plate to transmit optical radiation is not essential for all embodiments. In other words, a display device may be implemented without using a light guide plate. For example, a beam splitter may be used to separate light rays from the external world and from a virtual image source.

[0102] Alternatively, referring to FIG. 13, in another embodiment, a virtual object image source (270) may be positioned directly in front of at least one variable lens (280). For example, the virtual object image source (270) may be provided to each eye of the user. And, at least one variable lens (280) may be provided to correspond to each virtual object image source (270). In this case, the focus is adjusted by the at least one variable lens (280) so that the virtual object image provided by the virtual object image source (270) can be provided to a virtual focal plane. Thereby, the vergence-accommodation conflict of the user's eye can be resolved.

[0103] Meanwhile, in any embodiment, there may be no air gap between the variable optical cells constituting each variable lens. Additionally, it should be noted that the number of variable optical cells used in the variable lens according to the present invention is not necessarily limited to two.

[0104] In other embodiments, a larger number of variable optical cells may be provided to solve specific problems (e.g., expanding the optical power range, increasing the number of optical power correction steps, etc.). A variable lens formed by a stack (set) of variable optical cells may be arranged using a light guide plate.

[0105] Additionally, the variable optical cell may be configured to be polarization-dependent or non-polarization-dependent with respect to incident light. For example, a polarization-dependent configuration may be used in a variable optical cell having a strip electrode pattern in which electrodes are arranged in parallel. For example, as shown in FIG. 14, the first variable optical cell (331) may have vertically arranged strip electrodes (332), and the second variable optical cell (341) may have horizontally arranged strip electrodes (342). Here, as shown in FIG. 14, when the liquid crystal layer (333) has a direction along the X-axis, the variable optical cell can focus light with polarization along the X-axis. As shown in FIG. 15, when the liquid crystal layer (333) has a direction along the Y-axis, the light can focus with polarization along the Y-axis.

[0106] Various means and methods for focusing polarized or non-polarized light will be obvious to those skilled in the art. As an example, a drawing for focusing light is disclosed below. Development of a liquid crystal adaptive lens with a circular electrode for imaging applications by Sun YN et al. / / Integrated Optics: Devices, Materials and Technology VII. - International Society for Optics and Photonics (2003. - T. 4987. - C. 209-220.).

[0107] Light can be focused into a line (e.g., through a cylindrical lens) or a point (e.g., through a spherical lens). A cylindrical lens can be used to focus light polarized along the Y-axis, for example. In an embodiment having a strip electrode pattern, the direction of the electrodes can be used to focus light corresponding to the direction of the focus line and the direction of the director.

[0108] In a variable optical cell, incident light can be parallel to the polarization axis (e.g., the Y-axis). When using a cylindrical lens with a strip electrode pattern, for unpolarized light, two variable optical cells with strip electrodes are used to focus the light, and the direction of the electrode of the first variable optical cell is perpendicular to the direction of the electrode of the second variable optical cell, and the direction of the electrode of the first variable optical cell can coincide with the direction of the line where the light is focused.

[0109] The direction of the director of the first variable optical cell may be parallel to the X-axis (polarized along the X-axis), and the direction of the director of the second variable optical cell may be parallel to the Y-axis (polarized along the Y-axis). When focusing using a spherical lens with a strip electrode pattern, for example, when focusing light polarized along the Y-axis, light can be focused using two variable optical cells. With a parallel strip electrode pattern, the direction of the electrode in the first variable optical cell may be perpendicular to the direction of the electrode in the second variable optical cell. In this case, light can be focused to a point.

[0110] The orientation of the electrodes can be parallel to the line through which incident light focuses onto each variable optical cell using the strip electrodes. Each variable optical cell may have a director direction corresponding to the Y direction to focus, for example, light polarized along the Y-axis.

[0111] Referring to FIG. 16, in an embodiment having a ring electrode pattern (351), a variable optical cell (410) may be provided to focus light polarized along the Y-axis, for example, using a spherical lens. The direction of the variable optical cell (410) may be parallel to the polarization direction (Y-axis) of the incident light.

[0112] Referring to FIG. 17, in an embodiment having a ring electrode pattern (421), a variable optical cell (420) may be provided to focus light polarized along the X-axis, for example, using a spherical lens. The direction of the variable optical cell (420) may be parallel to the polarization direction (X-axis) of the incident light.

[0113] Referring to FIG. 18, in an embodiment having a strip electrode pattern, first to fourth variable optical cells (510)(520)(530)(540) may be provided to focus unpolarized light through a spherical lens. The first to fourth variable optical cells (510)(520)(530)(540) may each include first to fourth strip electrodes (511)(521)(531)(541) arranged in parallel. The first strip electrode (511) may be arranged in a direction perpendicular to the second strip electrode (521). The third strip electrode (531) may be arranged in a direction perpendicular to the fourth strip electrode (541). The first strip electrode (511) and the third strip electrode (531) may be arranged parallel to each other. The third strip electrode (531) and the fourth strip electrode (541) can be arranged parallel to each other.

[0114] The first and second variable optical cells (551)(552) may have a direction of a director corresponding to the Y direction to focus light polarized along the Y axis. The third and fourth variable optical cells (553)(554) may have a direction of a director corresponding to the X direction to focus light polarized along the X axis.

[0115] Referring to FIG. 19, in an embodiment having a ring electrode pattern (611), first and second variable optical cells (610) (620) may be provided to focus unpolarized light through a spherical lens. The first variable optical cell (610) may have a direction parallel to the Y-axis to focus light polarized along the Y-axis. The second variable optical cell (620) may have a direction parallel to the X-axis to focus light polarized along the X-axis.

[0116] The above description is merely a few embodiments for focusing using a variable optical cell having a strip electrode pattern and a ring electrode pattern, and the electrode structure is not limited thereto. It will be obvious to those skilled in the art that other embodiments may have the electrode pattern in other possible configurations. All embodiments that are clearly described and apparent from the information disclosed herein may be included within the scope of legal protection of the present invention.

[0117] The effect of the electrodes on the orientation (polarization) of the liquid crystal in the electrode pattern of a variable optical cell and the effect on the optical power of a variable lens including at least two variable optical cells are as follows. The voltage applied to the electrodes changes the orientation of the liquid crystal, and as a result, the refractive index value of the liquid crystal changes. Since the electrodes are arranged along the entire surface of the variable optical cell and a specific voltage is applied to each electrode, a voltage profile is formed in this way, which can form a phase profile of a lens having the required optical power.

[0118] The transition from the voltage profile to the phase profile is carried out by the phase's dependence on voltage, and this dependence can be determined by the properties of optically active materials such as liquid crystals. (For details, refer to Chen RH Liquid Crystal Displays: Fundamentals and Technology - John Wiley & Sons (2011) or Den Boer W. Active Matrix Liquid Crystal Displays: Fundamentals and Applications - Elsevier, 2011).

[0119] According to an exemplary embodiment, a display device for an augmented reality or virtual reality (AR / VR) system is provided, which may include at least one variable lens for each of the user's eyes. The variable lens may include at least two variable optical cells. If the number of variable optical cells is greater than two, a stack (set) of variable optical cells may be used. There may be no air gap between at least two variable optical cells.

[0120] For example, the number of variable optical cells is 6, which is the maximum number of variable optical cells when used in an AR augmented reality system with a lens thickness of 1.5 mm. However, this is merely an example and is not limited thereto. In an exemplary embodiment, the variable lens is thin, and the number of variable optical cells also depends on the thickness of the substrate used for the electrode pattern.

[0121] The optical power provided by such variable lenses is directly proportional to the number of variable optical cells; however, an increase in the number of variable optical cells used can negatively affect other parameters of the proposed device, potentially increasing its weight, size, and cost. Therefore, the optical power and the number of variable optical cells can be appropriately adjusted.

[0122] At least two variable optical cells having concentric, spaced-apart ring electrode patterns will be described. In an exemplary embodiment, the diameter of the lens having a variable focus formed by at least two variable optical cells may be, for example, 20 mm. However, this is only an example and is not limited thereto.

[0123] A variable lens comprising at least two variable optical cells may have steps of Δ = 0.25 diopters and provide a maximum optical power of Δ = 4 diopters. The maximum optical power should not be considered to limit or restrict the scope of the invention.

[0124] In an exemplary embodiment, the diffraction efficiency η(L) = 81.1% of the lens can be realized with L = 4 phase levels per Fresnel region. The radius of the variable lens can be r = 10 mm. For the electrode arrangement period of each electrode pattern of at least two stacks (sets) of the variable optical cell, a technical restriction can be established where the sum of the period (△R) equal to the size of the electrode and the distance between the electrodes (indicated by the symbol g in the mathematical formula) is 4 μm, and the distance between the electrodes is 1 μm.

[0125] And, with respect to the above lens parameters, considering the diffraction efficiency η(L) of the lens mentioned above, It is (see mathematical equation 3).

[0126] In this embodiment, for each of the two variable optical cells, the number of electrodes in the electrode pattern of the variable optical cell can be obtained as follows. For the first variable optical cell, the difference between the number of electrodes (N1) and the optical power (k1) per Fresnel region can be obtained from the following system inequality:

[0127] <Equation 4>

[0128] Here, known values ​​of L and Δ are substituted into the system inequality, the value of the constant A is calculated, and the system can be solved by finding the maximum possible value (k1). To manufacture an optimal variable optical cell, it is necessary to ensure the maximum possible variable of optical power under these limitations. For this value (k1), a minimum value (N1) can be found. To manufacture an optimal variable optical cell, it is necessary to find the minimum number of electrodes that provide this variable at a given optical power.

[0129] In addition, the value (k1) is needed to find the parameters k2 and N2 of the second variable optical cell, and the value (N1) is needed to calculate the radius and width of the ring electrode of the first variable optical cell.

[0130] For the second variable optical cell, the number of electrodes (N2) of the electrode pattern can be obtained from the following system inequality.

[0131] <Equation 5>

[0132] Value (k1) and given value (D max ) is substituted into the system inequality of the second variable optical cell, and this system can be solved by finding the possible maximum value (k2) (maximum value according to the given limit for the second variable optical cell). For the value (k2), a minimum value (N2) is found. The value (N2) is equal to the minimum number of electrodes required to provide the optical power variable. The value (N2) is needed to calculate the radius and width of the ring electrode of the second variable optical cell.

[0133] Additionally, in this embodiment, the radius of the ring electrode can be calculated for the first and second variable optical cells as follows. A general approach for calculating the radius of a concentric ring electrode is disclosed, for example, in Li G. et al.’s High-efficiency switchable electro-optical diffraction lens for ophthalmic applications / / Proceedings of the National Academy of Sciences. - 2006. - T. 103. - №. 16. - C. 6100-6104.

[0134] For each electrode with the number (mi,nj), the following can be calculated. In the first variable optical cell, it can be calculated as follows.

[0135] ,

[0136] <Equation 6>

[0137]

[0138] <Equation 7>

[0139] Here, r int is the inner radius of the electrode with the number (mi,nj), and r ext is the outer radius, mi is the number of Fresnel regions (150 in FIG. 3), and nj is the number of electrodes in one Fresnel region. Each Fresnel region (150) has a unique electrode number. That is, the first Fresnel region has electrodes (1, 2, 3, ...,) and the second Fresnel region has electrodes (1, 2, 3 ... etc.). is the maximum number of Fresnel regions for the first variable optical cell having radius (r), providing a dioptric step Δ at the radiation wavelength (λ), N1 is the number of electrodes per Fresnel region for the first variable optical cell (131 in FIG. 2), λ is the wavelength of the incident radiation, and g is the distance between the electrodes.

[0140] The width of the ring electrode for the first variable optical cell is calculated according to the following formula.

[0141] <Equation 8>

[0142] For the second variable optical cell, the same parameter is calculated according to the following equation

[0143] ,

[0144] ; <Equation 9>

[0145]

[0146] <Equation 10>

[0147]

[0148] <Equation 11>

[0149] Here, mj is the number of Fresnel regions (150 in FIG. 3) of the electrode pattern of the second variable optical cell, and nj is the number of electrodes in one Fresnel region m d2 is the maximum number of Fresnel regions for the second variable optical cell having radius (r), providing a dioptric step Δ at radiation wavelength (λ), and N2 is the number of electrodes per Fresnel region for the second variable optical cell (141 in FIG. 2).

[0150] As described above, the electrode patterns of the first variable optical cell and the second variable optical cell can be configured.

[0151] As an example, the electrodes of each variable optical cell may be made of indium tin oxide (ITO), but are not limited thereto. In other embodiments, the electrodes may be made of other transparent conductive materials widely known to those skilled in the art, e.g., indium oxide, tin oxide, indium zinc oxide (IZO), zinc oxide, etc.

[0152] According to exemplary embodiments, liquid crystal (in this case, the variable optical cell may be referred to as a variable liquid crystal cell) or polymer gel may be used as the optically active material in a variable optical cell. Specific examples of optically active materials will be apparent to those skilled in the art based on the information provided herein. Although the present invention is described using the example of a liquid crystal variable optical cell, the principle thereof can be equally applied to optically variable cells based on polymer gels and other optically active materials. In a liquid crystal variable optical cell according to exemplary embodiments, the adjustment of focus may be performed by electrodes constituting an electrode pattern in each variable optical cell. The adjustment mechanism of the electrodes is based on two principles.

[0153] According to the first principle, addressable electrodes, that is, electrodes of the electrode pattern of a variable optical cell to which a voltage corresponding to them is supplied, can be selected. The selection of addressable electrodes can be linked to the selection of the required optical power. The optical power can vary depending on the number of Fresnel regions. That is, addressable electrodes can be selected according to the number and location of the activated Fresnel regions.

[0154] According to the second principle, the value of the voltage applied to the electrode can be determined based on the voltage's dependence on phase, and the characteristics of any optically active material, that is, a material capable of introducing a phase delay depending on the applied voltage as light passes through it. When selecting the optically active material of a variable optical cell, it is necessary to know the dependence of the phase delay of light on the voltage at the electrode of the electrode pattern. Furthermore, to simulate the introduction of a specific optical power, it is necessary to apply a voltage to the electrode such that the phase delay profile of the output light matches that of an ideal thin lens having the same optical power. The entire process can be automated by standard algorithms well known in the art. For details, one may refer, for example, to US20150277151.

[0155] In an exemplary embodiment, the number of Fresnel regions may be 24 (md1 = 24) for the first variable optical cell and 96 (md2 = 96) for the second variable optical cell. The number of phase levels for both variable optical cells is L = 4. The maximum optical power of the first variable optical cell is 1 diopter, and the maximum optical power of the second variable optical cell is 3 diopters, which can provide a total maximum optical power of 4 diopters.

[0156] In the first variable optical cell, each Fresnel region may include 24 ring electrodes (Ni=24), and in the second variable optical cell, each Fresnel region may include 12 ring electrodes (N2=12). Accordingly, in an exemplary embodiment, there are 576 electrodes in the electrode pattern of the first variable optical cell and 1,152 electrodes in the electrode pattern of the second variable optical cell. These parameters are obtained for an exemplary embodiment and should not be interpreted as limiting the scope of the invention or as being preferred.

[0157] Additionally, as illustrated in FIG. 2, a variable lens comprising at least two variable optical cells may include a first substrate (132) associated with a first variable optical cell (131), a second substrate (136) which is a common substrate of the first variable optical cell (131) and the second adjustable optical cell (141), and a third substrate (140) associated with the second variable optical cell. On both sides of the second substrate (136), a second electrode (135) which is a common electrode of the first and second variable optical cells (131)(141) and a third electrode (137) may be provided. The second and third electrodes (135)(137)) may be coated with a conductor that is transparent in the visible light range, for example, indium tin oxide (ITO), indium oxide, tin oxide, indium zinc oxide (IZO), zinc oxide, etc.

[0158] As can be seen from the above calculation, with respect to the first substrate (132), the parameters for each electrode adjacent thereto are calculated as follows.

[0159] For each electrode with Fresnel region numbers mi = 1, … , d1, And, if the serial numbers of the electrodes within a single Fresnel region are nj = 1, … , N1, the inner radius and outer radius of the electrode are calculated according to the following formula:

[0160] <Equation 12>

[0161]

[0162] In the embodiment under consideration, the first electrode in the first Fresnel region of the first variable optical cell (131) has an outer radius It has the shape of a circle.

[0163] For the ring electrode (number other than 1) associated with the first substrate (132) of the first variable optical cell (131), the following formula applies.

[0164] <Equation 13>

[0165] For the third substrate (140) related to the second variable optical cell (141), the parameter for the fourth electrode (139) having a number (mi;nj) is calculated as follows.

[0166] The numbers mi= 1,… , md2, In the case of the fourth electrode (139) where nj= 1,…, N2, N2 is determined by Equation (5), and the inner and outer radii are calculated according to the following formula.

[0167]

[0168] <Equation 14>

[0169] The provided mathematical formula 11 may be applied to the ring-shaped fourth electrode (139) associated with the third substrate (140) of the second variable optical cell (141). The substrate material in the variable optical cell is selected from materials transparent to visible light, such as glass, plastic, and quartz, but is not limited thereto. The thickness of the substrate according to an exemplary embodiment may have a range of, for example, 3 to 200 μm. The thickness of the electrode deposited on the substrate may have a range of, for example, 30 to 200 nm, depending on the selected electrode material, for example, indium tin oxide (ITO), indium oxide, tin oxide, indium zinc oxide (IZO), zinc oxide, etc.

[0170] In a specific embodiment of the present invention, the principle for selecting the thickness of the substrate and the electrode based on the materials of the electrode and the substrate is well known in the art.

[0171] The electrode pattern of the variable optical cell according to an exemplary embodiment may be arranged in layers (e.g., 2-3 layers, but not limited thereto) to provide a small distance (e.g., 1 to 3 microns) between the electrodes. Since the total thickness of the variable lens depends relatively heavily on the thickness of the substrate compared to the thickness of the electrodes, the thickness of the substrate is important when using multiple variable optical cells.

[0172] As illustrated in FIG. 13, a display device for an AR / VR system may have a virtual object image source placed in front of the user's eyes to display virtual object images. When a virtual object image source is placed in front of the eyes in this way, it may obstruct the user from seeing the outside world. Therefore, in an augmented reality (AR) system, the virtual object image source may be transparent to provide the user with an observation of the outside world.

[0173] In the case of an augmented reality system, the display device enables the external world and a virtual object image superimposed on an image of the external world to be observed with the same clarity. Additionally, the position of the user's virtual object image can coincide with the position of a corresponding external object.

[0174] When a display device according to an exemplary embodiment is applied to an augmented reality (AR) system, the virtual object image source may be manufactured from a material that is transparent to the visible light range, such as glass, plastic, or quartz. However, it is not limited thereto.

[0175] When a display device is applied to a virtual reality (VR) system, the virtual object image source may include, for example, an active matrix having a liquid crystal display (LCD), organic LED (OLED), inorganic LED (ILED), organic light-emitting diode (AMOLED), transparent organic light-emitting diode (TOLED), quantum dot display (QOLED, QLED), etc. However, the display device is not limited to these.

[0176] In an embodiment for use in an AR system and a VR system, one virtual object image source or multiple virtual object image sources may be provided. For example, one virtual object image source may be provided for each eye of the user. In this case, as described above, by using a variable lens comprising at least two variable optical cells, a virtual object (along with external world objects if necessary) having the depth of field required for the user's field of vision can be displayed. Additionally, if necessary, to correct the user's vision, such as myopia / sightedness or presbyopia, the at least two variable optical cells perform a role similar to that of the eye's lens and cornea, and the possibility of dynamic adjustment of the corneal analog may be provided in addition to the possibility of dynamic adjustment of the eye's lens analog (during the adjustment process). The corneal analog may not exist in the human eye, but may exist in the eye patterns of some birds of prey, such as the red-tailed hawk, where the shape of the cornea can change.

[0177] The first variable optical cell provides "coarse adjustment" of eye accommodation within the same diopter, and the second variable optical cell can provide "fine adjustment" within, for example, three diopters. This is the total optical power It can provide the full range of optical power provided by the variable lens according to the exemplary embodiment. This eliminates the vergence-accommodation conflict of the user's eye and allows the user to observe images of virtual objects along with images of the external world, if necessary, without discomfort.

[0178] A display device according to an exemplary embodiment may be part of an AR / VR system for various purposes, which may be implemented in the form of, for example, a virtual reality helmet or an augmented reality helmet, smart glasses, a headset, or a head-mounted device. A display device according to various embodiments may include one variable lens for a user's eye or one variable lens for each user's eye. In a display device according to an exemplary embodiment, the focus adjustment of the variable lens may be controlled by various software and / or hardware by adjusting the voltage applied to the addressable electrode in the electrode pattern of the corresponding variable optical cell.

[0179] The control of the focus adjustment of the variable lens may be specifically designed for this purpose, or the display device may include one or more processors, integrated circuits, etc., included in the AR / VR system. These functions may be provided along with other functions for the operation of the AR / VR system. One or more processors may control the focus adjustment of the variable lens under the control of software stored on a computer-readable medium and / or distributed by known wired and / or wireless data transmission technologies. The software may be implemented in any suitable programming language and / or in the form of executable machine code and may be stored in the memory of the AR / VR system or on an external medium including a remote medium from the AR / VR system. The software may be connected to the AR / VR system via a well-known data network. All known embodiments of one or more processors, computer programs, and computer-readable media suitable for controlling the focus adjustment of the variable lens in the display device according to the exemplary embodiment may be included within the scope of legal protection of the present invention. In the display device according to the exemplary embodiment, the focus of the variable lens may be controlled based on various input data. Among these, data of virtual object images, displayed to the user of the AR / VR system and represented as a virtual object image source according to one or more processors, user input data, data related to the user's vision characteristics, and data from one or more sensors included in the AR / VR system, and / or data from external sources transmitted to the AR / VR system via any known wired and / or wireless data network, etc., are obvious to those skilled in the art.

[0180] Those skilled in the art will understand that only some of the possible examples of the technology, materials, and technical means by which exemplary embodiments can be implemented are described and illustrated in the drawings. The above detailed description of embodiments of the invention is not intended to limit or define the scope of legal protection of the invention. Other embodiments falling within the scope of the invention may be considered by those skilled in the art after carefully reading the above description with reference to the accompanying drawings, and all such obvious modifications, changes, and / or equivalent substitutions are within the scope of the invention. All sources of prior art cited and discussed herein are incorporated by reference to the invention as applicable. Although the invention has been described and illustrated with reference to various embodiments, those skilled in the art will understand that various variations in form and specific details may be made without departing from the scope of the invention. It is defined only by the claims and equivalents provided below. Explanation of the symbols

[0181] LC1, LC2: Variable lenses 110,210: Virtual object image source 120,220: Light guide plate 131: First variable optical cell 132,136,140: Substrate 133,135,137,139: Electrodes 150: Fresnel zone

Claims

Claim 1 At least one virtual object image source; and at least one variable lens; wherein the at least one variable lens comprises at least two variable optical cells, each of the at least two variable optical cells comprises an electrode pattern for adjusting the focal length of the at least one variable lens, the electrode pattern is configured such that the optical power of the at least one variable lens changes in an equidistant dioptic step, and the at least two variable optical cells comprise a first variable optical cell having a first electrode, a second electrode, and a first liquid crystal layer between the first electrode and the second electrode, and a second variable optical cell having a third electrode, a fourth electrode, and a second liquid crystal layer between the third electrode and the fourth electrode, wherein the first electrode is provided on a first substrate, the second electrode is provided on one side of a second substrate, the third electrode is provided on the other side of the second substrate, and the fourth electrode is provided on a third substrate, wherein the first electrode and the fourth electrode each comprise a ring electrode pattern arranged spaced apart from each other, and the second electrode and the third electrode each comprise a common electrode, and the first electrode and the fourth electrode comprise a plurality of Fresnel regions A display device comprising, wherein each of the plurality of Fresnel regions includes a different number of electrodes. Claim 2 A display device according to claim 1, wherein the equidistant diopter step Δ is 0.25 diopters. Claim 3 delete Claim 4 A display device according to claim 1, wherein the at least one variable lens comprises a first variable lens and a second variable lens, and further comprises a light guide plate that transmits light from the virtual object image source, wherein the light guide plate is disposed between the first variable lens and the second variable lens. Claim 5 ◈Claim 5 was abandoned upon payment of the registration fee.◈ A display device according to Claim 4, wherein the first variable lens is configured to be positioned in front of the user's eyes. Claim 6 A display device according to claim 1, further comprising a light guide plate that transmits light from the virtual object image source, wherein the at least one variable lens comprises a first variable lens disposed between the virtual object image source and the light guide plate and a second variable lens disposed outside of the light guide plate. Claim 7 ◈Claim 7 was abandoned upon payment of the registration fee.◈ A display device according to Claim 1, wherein the electrode pattern comprises concentric ring electrodes and a circular electrode disposed at the center of the concentric ring electrodes. Claim 8 ◈Claim 8 was abandoned upon payment of the registration fee.◈ The display device according to Claim 1, wherein the electrode pattern comprises parallel strip electrodes arranged in a horizontal or vertical direction. Claim 9 A display device according to claim 1, wherein the at least one variable lens comprises a first variable lens having a first optical power and a second variable lens having a second optical power having the same magnitude as the first optical power but opposite sign. Claim 10 A display device according to claim 1, wherein the at least one variable lens comprises a first variable lens having a first optical power and a second optical power for correcting a user's refraction error, and a second variable lens having a third optical power having the same magnitude as the first optical power but opposite sign. Claim 11 ◈Claim 11 was abandoned upon payment of the registration fee.◈ The display device according to Claim 1, wherein at least one variable lens comprises a first variable lens having a first optical power and a second optical power for correcting a user's refraction error, and a second variable lens having a third optical power equal to the second optical power. Claim 12 ◈Claim 12 was abandoned upon payment of the registration fee.◈ A display device according to Claim 1, wherein the at least two variable optical cells comprise a polarization-dependent electrode pattern. Claim 13 ◈Claim 13 was abandoned upon payment of the registration fee.◈ A display device according to Claim 1, wherein the at least two variable optical cells comprise polarization-independent electrode patterns. Claim 14 ◈Claim 14 was abandoned upon payment of the registration fee.◈ A display device according to Claim 1, wherein at least one variable lens is circular. Claim 15 ◈Claim 15 was abandoned upon payment of the registration fee.◈ A display device according to Claim 1, wherein at least one variable lens has a rectangular shape or a polygonal shape. Claim 16 A display device according to claim 1, wherein at least one variable lens is configured to have optical power for correcting a user's refraction error. Claim 17 ◈Claim 17 was abandoned upon payment of the registration fee.◈ A display device according to Claim 1, wherein at least one variable lens is configured to have 0 optical power. Claim 18 A display device according to claim 1, wherein at least one variable lens is configured to have a total optical power in the range of (-4) to (+4) diopters. Claim 19 An augmented reality (AR) system comprising a display device according to any one of claims 1, 2, 4 through 18. Claim 20 A virtual reality (VR) system comprising a display device according to any one of claims 1, 2, 4 through 18.

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