Patent Publication Number: US-2020301148-A1

Title: Optical device

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority from and the benefit of Korean Patent Application No. 10-2019-0030469, filed on Mar. 18, 2019, which is hereby incorporated by reference for all purposes as if fully set forth herein. 
     BACKGROUND 
     Field 
     Exemplary embodiments of the present invention relate to an optical device. 
     Discussion of the Background 
     Augmented reality is a technique of superimposing a virtual image on a real image viewed by a user&#39;s eyes and displaying them as a single image. The virtual image may be an image in the form of text or graphics, and the real image may be information about an actual object observed in the field of view of a device. 
     An optical device may include a plurality of optical members for changing an optical path of a virtual image displayed on a display device to provide the virtual image to the user&#39;s eyes. In this case, the optical path from the display device to the user&#39;s eyes is long and complicated, and the size of the optical device may be increased due to the plurality of optical members. 
     Recently, the optical device is provided in the form of a pair of glasses so that the user can easily carry it, and it can be easily worn or taken off. When the size of the optical device increases, it is difficult to realize the optical device. By using a convex lens having a short focal length as an optical member, it is possible to reduce the optical path from the display device to the user&#39;s eyes. However, in this case, the image quality of the virtual image viewed by the user may be lowered due to the chromatic aberration of the convex lens having a short focal length. 
     The above information disclosed in this Background section is only for understanding of the background of the inventive concepts, and, therefore, it may contain information that does not constitute prior art. 
     SUMMARY 
     Embodiments of the present disclosure provide an optical device capable of preventing or reducing a decrease in image quality of a virtual image viewed by a user due to chromatic aberration of a convex lens having a short focal length. 
     Additional features of the inventive concepts will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of is the inventive concepts. 
     According to one or more exemplary embodiments of the invention, an optical device includes: a lens including a first lens portion having a first curved surface with a first curvature and a second lens portion having a second curved surface corresponding to the first curved surface; a display device disposed on a first side surface of the lens; a convex lens disposed between the first side surface of the lens and the display device; and a reflector disposed on the first curved surface of the first lens portion of the lens, the reflector configured to reflect light of the display device refracted by the convex lens toward a user&#39;s eye. 
     The lens may include an adhesive disposed between the first lens portion and the second lens portion, the adhesive adhering the first curved surface of the first lens portion to the second curved surface of the second lens portion. 
     The first curved surface of the first lens portion may be concave away from the second lens portion, and the second curved surface of the second lens portion may be convex toward the first curved surface of the first lens portion. 
     The first curvature may be less than or equal to 0.01 mm −1 . 
     The reflector may include a reflecting surface having a concave curved surface. 
     A first lens surface of the convex lens facing the display device may be convex toward the display device, and a second lens surface of the convex lens facing the lens may be flat. 
     A first lens surface of the convex lens facing the display device may be flat, and a second lens surface of the convex lens facing the lens may be convex. 
     A first lens surface of the convex lens facing the display device may be convex toward the display device, and a second lens surface of the convex lens facing the lens may be convex toward the lens. 
     The optical device may further include: a first spacer disposed between the display device and the convex lens; and a second spacer disposed between the convex lens and the lens. 
     According to one or more exemplary embodiments of the invention, an optical device includes: a lens including a first lens portion having a first curved surface with a first curvature and a second lens portion having a second curved surface corresponding to the first curved surface; and a first reflector and a second reflector disposed on the first curved surface of the lens, the first reflector and the second reflector configured to reflect light of the display device refracted by the convex lens toward a user&#39;s eye, wherein the first reflector and the second reflector comprise reflecting surfaces having a concave curved surface. 
     A curvature of the reflecting surface of the first reflector may be equal to a curvature of the reflecting surface of the second reflector. 
     The first reflector and the second reflector may be arranged in parallel in a width direction of the lens. 
     The first reflector and the second reflector may not be arranged in parallel in a height direction of the lens. 
     The optical device may further include: a display device disposed on a first side surface of the lens; and a convex lens disposed between the first side surface of the lens and the display device. 
     The first curved surface of the first lens portion may be concave away from the second lens portion, and the second curved surface of the second lens portion may be convex toward the first curved surface of the first lens portion. 
     The first curvature is less than or equal to 0.01 mm −1 . 
     The optical device may further include: a first spacer disposed between the display device and the convex lens; and a second spacer disposed between the convex lens and the lens. 
     It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate exemplary embodiments of the invention, and together with the description serve to explain the inventive concepts. 
         FIG. 1  is a perspective view showing an optical device according to an exemplary embodiment. 
         FIG. 2  is an exploded perspective view showing an optical device according to an exemplary embodiment. 
         FIG. 3  is a perspective view showing an example of a first lens, a first convex lens and a first display device of  FIG. 2 . 
         FIG. 4  is an exemplary diagram illustrating an augmented reality realizing method of an optical device according to an exemplary embodiment. 
         FIG. 5  is an exploded perspective view showing an example of the first lens and the reflectors of  FIG. 3 . 
         FIG. 6  is a plan view showing an example of the first lens of  FIG. 3 . 
         FIG. 7  is a front view showing an example of the first lens of  FIG. 3 . 
         FIG. 8  is a side view showing an example taken along a sectional line I-I′ of  FIG. 6 . 
         FIG. 9  is a side view showing an example taken along a sectional line II-II′ of  FIG. 6 . 
         FIG. 10  is a side view showing an example taken along a sectional line of  FIG. 7 . 
         FIG. 11  is a side view showing an example taken along a sectional line IV-IV′ of  FIG. 7 . 
         FIGS. 12, 13, and 14  show examples of a virtual image displayed on the first display device, which is displayed to the user according to the curvature of the first curved surface of the first lens. 
         FIG. 15  is a plan view showing an example of the first display device of  FIG. 3 . 
         FIG. 16  is a cross-sectional view specifically showing a display area of the first display panel of  FIG. 14 . 
         FIG. 17  is an exploded perspective view showing an optical device according to an exemplary embodiment. 
         FIG. 18  is an exploded perspective view showing an optical device according to another exemplary embodiment. 
     
    
    
     DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS 
     In the following description, for the purposes of explanation, numerous specific is details are set forth in order to provide a thorough understanding of various exemplary embodiments or implementations of the invention. As used herein “embodiments” and “implementations” are interchangeable words that are non-limiting examples of devices or methods employing one or more of the inventive concepts disclosed herein. It is apparent, however, that various exemplary embodiments may be practiced without these specific details or with one or more equivalent arrangements. In other instances, well-known structures and devices are shown in block diagram form in order to avoid unnecessarily obscuring various exemplary embodiments. Further, various exemplary embodiments may be different, but do not have to be exclusive. For example, specific shapes, configurations, and characteristics of an exemplary embodiment may be used or implemented in another exemplary embodiment without departing from the inventive concepts. 
     Unless otherwise specified, the illustrated exemplary embodiments are to be understood as providing exemplary features of varying detail of some ways in which the inventive concepts may be implemented in practice. Therefore, unless otherwise specified, the features, components, modules, layers, films, panels, regions, and/or aspects, etc. (hereinafter individually or collectively referred to as “elements”), of the various embodiments may be otherwise combined, separated, interchanged, and/or rearranged without departing from the inventive concepts. 
     The use of cross-hatching and/or shading in the accompanying drawings is generally provided to clarify boundaries between adjacent elements. As such, neither the presence nor the absence of cross-hatching or shading conveys or indicates any preference or requirement for particular materials, material properties, dimensions, proportions, commonalities between illustrated elements, and/or any other characteristic, attribute, property, etc., of the elements, unless specified. Further, in the accompanying drawings, the size and relative sizes of is elements may be exaggerated for clarity and/or descriptive purposes. When an exemplary embodiment may be implemented differently, a specific process order may be performed differently from the described order. For example, two consecutively described processes may be performed substantially at the same time or performed in an order opposite to the described order. Also, like reference numerals denote like elements. 
     When an element, such as a layer, is referred to as being “on,” “connected to,” or “coupled to” another element or layer, it may be directly on, connected to, or coupled to the other element or layer or intervening elements or layers may be present. When, however, an element or layer is referred to as being “directly on,” “directly connected to,” or “directly coupled to” another element or layer, there are no intervening elements or layers present. To this end, the term “connected” may refer to physical, electrical, and/or fluid connection, with or without intervening elements. Further, the X-axis, the Y-axis, and the Z-axis are not limited to three axes of a rectangular coordinate system, such as the x, y, and z axes, and may be interpreted in a broader sense. For example, the X-axis, the Y-axis, and the Z-axis may be perpendicular to one another, or may represent different directions that are not perpendicular to one another. For the purposes of this disclosure, “at least one of X, Y, and Z” and “at least one selected from the group consisting of X, Y, and Z” may be construed as X only, Y only, Z only, or any combination of two or more of X, Y, and Z, such as, for instance, XYZ, XYY, YZ, and ZZ. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. 
     Although the terms “first,” “second,” etc. may be used herein to describe various types of elements, these elements should not be limited by these terms. These terms are used to distinguish one element from another element. Thus, a first element discussed below could be termed a second element without departing from the teachings of the disclosure. 
     Spatially relative terms, such as “beneath,” “below,” “under,” “lower,” “above,” “upper,” “over,” “higher,” “side” (e.g., as in “sidewall”), and the like, may be used herein for descriptive purposes, and, thereby, to describe one elements relationship to another element(s) as illustrated in the drawings. Spatially relative terms are intended to encompass different orientations of an apparatus in use, operation, and/or manufacture in addition to the orientation depicted in the drawings. For example, if the apparatus in the drawings is turned over, elements described as “below” or “beneath” other elements or features would then be oriented “above” the other elements or features. Thus, the exemplary term “below” can encompass both an orientation of above and below. Furthermore, the apparatus may be otherwise oriented (e.g., rotated 90 degrees or at other orientations), and, as such, the spatially relative descriptors used herein interpreted accordingly. 
     The terminology used herein is for the purpose of describing particular embodiments and is not intended to be limiting. As used herein, the singular forms, “a,” “an,” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. Moreover, the terms “comprises,” “comprising,” “includes,” and/or “including,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, components, and/or groups thereof, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. It is also noted that, as used herein, the terms “substantially,” “about,” and other similar terms, are used as terms of approximation and not as terms of degree, and, as such, are utilized to account for inherent deviations in measured, calculated, and/or provided values that would be recognized by one of ordinary skill in the art. 
     Various exemplary embodiments are described herein with reference to sectional and/or exploded illustrations that are schematic illustrations of idealized exemplary embodiments and/or intermediate structures. As such, variations from the shapes of the illustrations as a result, for example, of manufacturing techniques and/or tolerances, are to be expected. Thus, exemplary embodiments disclosed herein should not necessarily be construed as limited to the particular illustrated shapes of regions, but are to include deviations in shapes that result from, for instance, manufacturing. In this manner, regions illustrated in the drawings may be schematic in nature and the shapes of these regions may not reflect actual shapes of regions of a device and, as such, are not necessarily intended to be limiting. 
     As customary in the field, some exemplary embodiments are described and illustrated in the accompanying drawings in terms of functional blocks, units, and/or modules. Those skilled in the art will appreciate that these blocks, units, and/or modules are physically implemented by electronic (or optical) circuits, such as logic circuits, discrete components, microprocessors, hard-wired circuits, memory elements, wiring connections, and the like, which may be formed using semiconductor-based fabrication techniques or other manufacturing technologies. In the case of the blocks, units, and/or modules being implemented by microprocessors or other similar hardware, they may be programmed and controlled using software (e.g., microcode) to perform various functions discussed herein and may optionally be driven by firmware and/or software. It is also contemplated that each block, unit, and/or module may be implemented by dedicated hardware, or as a combination of dedicated hardware to perform some functions and a processor (e.g., one or more programmed microprocessors and associated circuitry) to perform other functions. Also, each block, unit, and/or module of some exemplary embodiments may be physically separated into two or more interacting and discrete blocks, units, and/or modules without departing from the scope of the inventive concepts. Further, the blocks, units, and/or modules of some exemplary embodiments may be physically combined into more complex blocks, units, and/or modules without departing from the scope of the inventive concepts. 
     Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure is a part. Terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and should not be interpreted in an idealized or overly formal sense, unless expressly so defined herein. 
       FIG. 1  is a perspective view showing an optical device according to an exemplary embodiment.  FIG. 2  is an exploded perspective view showing an optical device according to an exemplary embodiment. 
     Referring to  FIGS. 1 and 2 , an optical device  1  according to an exemplary embodiment includes a support frame  20 , a first lens frame  21 , a second lens frame  22 , a first frame leg  31 , a second frame leg  32 , a first lens  110 , a second lens  120 , a first display device  210 , a second display device  220 , a first convex lens  310 , a second convex lens  320 , first to fifth reflectors  411 ,  412 ,  413 ,  414 , and  415 , and sixth to tenth reflectors  421 ,  422 ,  423 ,  424 , and  425 . 
     The terms “above,” “top” and “upper surface” as used herein refer to a Z-axis direction, and the terms “below,” “bottom”, “lower surface” as used herein refers to a direction opposite to the Z-axis direction. Further, the term “left” as used herein refers to a direction opposite to an X-axis direction, the term “right” as used herein refers to the X-axis direction, the term “upper” as used herein refers to a Y-axis direction, and the term “lower” as used herein refers to a direction opposite to the Y-axis direction. 
     The support frame  20  serves to support the first lens  110  and the second lens  120  in cooperation with the first lens frame  21  and the second lens frame  22 . The first lens  110  may be surrounded by the support frame  20  and the first lens frame  21 . The second lens  120  may be surrounded by the support frame  20  and the second lens frame  22 . 
     The support frame  20  may be disposed on the upper side surface of the first lens  110  and the upper side surface of the second lens  120 . The support frame  20  may be elongated in a width direction (X-axis direction) of the first lens  110 . 
     The first lens frame  21  may be disposed on the left side surface, the lower side surface and the right side surface of the first lens  110 . The first lens frame  21  may be coupled to the support frame  20 . The second lens frame  22  may be disposed on the left side surface, the lower side surface, and the right side surface of the second lens  120 . The second lens frame  22  may be coupled to the support frame  20 . Each of the first lens frame  21  and the second lens frame  22  may include a nose pad. 
     Although it is illustrated in  FIG. 2  that the support frame  20 , the first lens frame  21  and the second lens frame  22  are separately formed and coupled, the present disclosure is not limited thereto. The support frame  20 , the first lens frame  21  and the second lens frame  22  may be formed integrally with each other. 
     The first frame leg  31  may be fixed to the left end of the lower side surface of the support frame  20 . The second frame leg  32  may be fixed to the right end of the lower side surface of the support frame  20 . Each of the first frame leg  31  and the second frame leg  32  may be fixed to the support frame  20  by a fixing member such as a screw. 
     Each of the support frame  20 , the first lens frame  21 , the second lens frame  22 , the first frame leg  31  and the second frame leg  32  may include plastic, metal, or both plastic and metal. The first lens frame  21  and the second lens frame  22  may be omitted. 
     Each of the first lens  110  and the second lens  120  may be formed of glass or plastic in a transparent or translucent manner. Thus, the user can view a real image through the first lens  110  and the second lens  120 . The first lens  110  and the second lens  120  may have a refractive power in consideration of the visual acuity of the user. 
     Each of the first lens  110  and the second lens  120  may be formed as a hexahedron having an upper surface, a lower surface and first to fourth side surfaces which are quadrangular. The upper surface of the first lens  110  is a surface facing a right eye RE of the user, and may be an exit surface from which the light of the first display device  210  is emitted by the first to fourth reflectors  411 ,  412 ,  413 , and  414 . The lower surface of the first lens  110  may be an outer surface of the first lens  110 . The upper surface of the second lens  120  is a surface facing a left eye LE of the user, and may be an exit surface from which the light of the second display device  220  is emitted by the fifth to eighth reflectors  421 ,  422 ,  423 , and  424 . The lower surface of the second lens  120  may be an outer surface of the second lens  120 . 
     Each of the first lens  110  and the second lens  120  is not limited to that shown in  FIGS. 1 and 2 , and may be formed as a polyhedron having a first surface, a second surface and side surfaces, which are polygonal. In addition to the polyhedron, each of the first lens  110  and the second lens  120  may be formed in other shapes such as a cylinder, an elliptic cylinder, a semicircular cylinder, a semi-elliptic cylinder, a distorted cylinder, or a distorted semicircular cylinder. The distorted cylinder and semicircular cylinder refer to a cylinder and a semicircular cylinder having a non-constant diameter. 
     The first to fifth reflectors  411 ,  412 ,  413 ,  414 , and  415  are disposed in the first lens  110 . The sixth to tenth reflectors  421 ,  422 ,  423 ,  424 , and  425  are disposed in the second lens  120 . Each of the first to fifth reflectors  411 ,  412 ,  413 ,  414 , and  415  and the sixth to tenth reflectors  421 ,  422 ,  423 ,  424 , and  425  may be a small mirror such as a pin mirror. Although  FIGS. 1 and 2  illustrate that each of the first to fifth reflectors  411 ,  412 ,  413 ,  414 , and  415  and the sixth to tenth reflectors  421 ,  422 ,  423 ,  424 , and  425  has a circular cross section in a plan view, it may have an elliptical or polygonal cross section in addition to the circular shape. 
     The first to fifth reflectors  411 ,  412 ,  413 ,  414 , and  415  may reflect an image displayed on the first display device  210  and provide the reflected image to the user&#39;s right eye RE. The sixth to tenth reflectors  421 ,  422 ,  423 ,  424 , and  425  may reflect an image displayed on the second display device  220  and provide the reflected image to the user&#39;s left eye LE. 
     Each of the first to fifth reflectors  411 ,  412 ,  413 ,  414 , and  415  and the sixth to tenth reflectors  421 ,  422 ,  423 ,  424 , and  425  may be formed to be smaller in size than the pupil of the right eye RE or left eye LE. For example, each of the first to fifth reflectors  411 ,  412 ,  413 ,  414 , and  415  and the sixth to tenth reflectors  421 ,  422 ,  423 ,  424 , and  425  may be formed to have a diameter of 500 μm to 4 mm. In this case, since the user focuses on the real image, it is difficult to recognize the first to fifth reflectors  411 ,  412 ,  413 ,  414 , and  415  and the sixth to tenth reflectors  421 ,  422 ,  423 ,  424 , and  425 . However, as the size of each of the first to fifth reflectors  411 ,  412 ,  413 ,  414 , and  415  and the sixth to tenth reflectors  421 ,  422 ,  423 ,  424 , and  425  decreases, the luminance of the image of the first display device  210  provided to the user&#39;s right eye RE and the luminance of the image of the second display device  220  provided to the user&#39;s left eye LE may decrease. Thus, the size of each of the first to fifth reflectors  411 ,  412 ,  413 ,  414 , and  415  and the sixth to tenth reflectors  421 ,  422 ,  423 ,  424 , and  425  may be set in consideration of whether the user can recognize the mirror and the luminance of the image provided to the user. 
     Each of the first to fifth reflectors  411 ,  412 ,  413 ,  414 , and  415  and the sixth to tenth reflectors  421 ,  422 ,  423 ,  424 , and  425  may have a cylindrical shape as shown in  FIGS. 1 and 2 . In this case, each of the first to fifth reflectors  411 ,  412 ,  413 ,  414 , and  415  and the sixth to tenth reflectors  421 ,  422 ,  423 ,  424 , and  425  may include two bottom surfaces, and one of the two bottom surfaces facing the first display device  210  or the second display device  220  may be defined as a reflecting surface. 
     The reflecting surface of each of the first to fifth reflectors  411 ,  412 ,  413 ,  414 , and  415  and the sixth to tenth reflectors  421 ,  422 ,  423 ,  424 , and  425  may be formed as a concave curved surface having a curvature. In this case, the image of the first display device  210  reflected by the first to fifth reflectors  411 ,  412 ,  413 ,  414 , and  415  may have a predetermined focal length. Further, the image of the second display device  220  reflected by the sixth to tenth reflectors  421 ,  422 ,  423 ,  424 , and  425  may have a predetermined focal length. 
     Although  FIGS. 1 and 2  illustrate that five reflectors  411 ,  412 ,  413 ,  414 , and  415  are disposed in the first lens  110  and five reflectors  421 ,  422 ,  423 ,  424 , and  425  are disposed in the second lens  120 , the number of reflectors disposed in the first lens  110  and the number of reflectors disposed in the second lens  120  are not limited thereto. More than five reflectors may be disposed in each of the first lens  110  and the second lens  120 . 
     Each of the first display device  210  and the second display device  220  displays a virtual image for realizing an augmented reality. The first display device  210  may include a first display panel  211 , a first circuit board  212  having a first driving circuit. The second display device  220  may include a second display panel  221 , a second circuit board  222  having a second driving circuit. 
     The first display panel  211  may be disposed on a first side surface of the first lens  110  and the second display panel  221  may be disposed on a first side surface of the second lens  120 . For example, the first display panel  211  may be disposed on the upper side surface of the first lens  110 , and the second display panel  221  may be disposed on the upper side surface of the second lens  120 . In this case, the first display panel  211  and the second display panel  221  can be covered by the support frame  20 . The arrangement position of the first display panel  211  and the arrangement position of the second display panel  221  are not limited to those shown in  FIGS. 1 and 2 . 
     Each of the first display panel  211  and the second display panel  221  may be a flexible display panel with flexibility, which can be bent. For example, each of the first display panel  211  and the second display panel  221  may be an organic light emitting display panel or an organic light emitting display panel including quantum dots. In this specification, a case where each of the first display panel  211  and the second display panel  221  is formed as an organic light emitting display panel as shown in  FIG. 16  will be described mainly. 
     The first circuit board  212  may be attached to one end and the other end of the first display panel  211 . The second circuit board  222  may be attached to one end of the second display panel  221 . The first circuit board  212  and the second circuit board  222  may be flexible printed circuit boards, which can be bent. 
     A power supply unit for supplying power to the first display device  210  and the second display device  220  may be embedded in any one of the first frame leg  31  and the second frame leg  32 . In this case, a first cable for connecting the first circuit board  212  to the power supply unit and a second cable for connecting the second circuit board  222  to the power supply unit may be additionally disposed. When the power source unit is embedded in the second frame leg  32 , the first cable may be extended to the second frame leg  32 . The length of the first cable may be longer than the length of the second cable. 
     The first convex lens  310  may be disposed between the first side surface of the first lens  110  and the first display device  210 , and the second convex lens  320  may be disposed between the first side surface of the second lens  120  and the second display device  220 . 
     Each of the first convex lens  310  and the second convex lens  320  may be formed as a flat convex lens. For example, as shown in  FIG. 2 , each of the first convex lens  310  and the second convex lens  320  may be formed such that one surface facing the first display device  210  is flat and the other surface facing the first side surface of the first lens  110  is convex. Alternatively, as shown in  FIG. 18 , each of the first convex lens  310  and the second convex lens  320  may be formed such that one surface facing the first display device  210  is convex and the other surface facing the first side surface of the first lens  110  is flat. 
     Alternatively, each of the first convex lens  310  and the second convex lens  320  may be formed as a biconvex lens. For example, as shown in  FIG. 17 , each of the first convex lens  310  and the second convex lens  320  may be formed such that both of one surface facing the first display device  210  or the second display device  220  and the other surface facing the first side surface of the first lens  110  are convex. 
     The reflecting surface of each of the first to fifth reflectors  411 ,  412 ,  413 ,  414 , and  415  and the sixth to tenth reflectors  421 ,  422 ,  423 ,  424 , and  425  may be formed as a concave curved surface having a curvature. The distance at which the image of the first display device  210  is viewed may be determined by the focal length of the first convex lens  310  and the focal length of each of the first to fifth reflectors  411 ,  412 ,  413 ,  414 , and  415 . The focal length of each of the first to fifth reflectors  411 ,  412 ,  413 ,  414 , and  415  may be determined depending on the curvature of the reflecting surface of each of the first to fifth reflectors  411 ,  412 ,  413 ,  414 , and  415 . In addition, the curvature of the reflecting surface of each of the first to fifth reflectors  411 ,  412 ,  413 ,  414 , and  415  may be determined by the curvature of a first curved surface CS 1 . The distance at which the image of the second display device  220  is viewed may be determined by the focal length of the second convex lens  320  and the focal length of each of the sixth to tenth reflectors  421 ,  422 ,  423 ,  424 , and  425 . The focal length of each of the sixth to tenth reflectors  421 ,  422 ,  423 ,  424 , and  425  may be determined depending on the curvature of the reflecting surface of each of the sixth to tenth reflectors  421 ,  422 ,  423 ,  424 , and  425 . In addition, the curvature of the reflecting surface of each of the sixth to tenth reflectors  421 ,  422 ,  423 ,  424 , and  425  may be determined by the curvature of the first curved surface CS 1 . 
     Even if the focal length of the first convex lens  310  is not reduced, the distance at which the image of the first display device  210  is viewed may be shortened by the focal length of each of the first to fifth reflectors  411 ,  412 ,  413 ,  414 , and  415 . Further, even if the focal length of the second convex lens  320  is not reduced, the distance at which the image of the second display device  220  is viewed may be shortened by the focal length of each of the sixth to tenth reflectors  421 ,  422 ,  423 ,  424 , and  425 . Therefore, even if the focal length of each of the first convex lens  310  and the second convex lens  320  is not reduced, an optical path from the display device to the user&#39;s eyes can be reduced, thereby reducing the size of the optical device. Also, it is possible to prevent or suppress deterioration in the image quality of the virtual image viewed by the user due to the chromatic aberration of the first convex lens  310  and the second convex lens  320  having short focal lengths. 
     A polarizing film may be disposed between the first side surface of the first lens  110  and the first convex lens  310  and between each side surface of the second lens  120  and the second convex lens  320 . The polarizing film may include a phase retardation film such as a linear polarizer plate and a quarter-wave (λ/4) plate. In this case, the linear polarizer plate may be disposed on the first side surface of the first lens  110  or the first side surface of the second lens  120 , and the phase retardation film may be disposed between the linear polarizer plate and the first convex lens  310  or the second convex lens  320 . Accordingly, the polarizing film can prevent or suppress light incident on the first display device  210  from the first side surface of the first lens  110  from being reflected by the first display device  210  and emitted to the first side surface of the first lens  110 , while providing the light of the first display device  210  to the first side surface of the first lens  110 . Also, the polarizing film can prevent or suppress light incident on the second display device  220  from the first side surface of the second lens  120  from being reflected by the second display device  220  and emitted to the first side surface of the second lens  120 , while providing the light of the second display device  220  to the first side surface of the second lens  120 . 
       FIG. 3  is a perspective view showing an example of the first lens, the first convex lens and the first display device of  FIG. 2 .  FIG. 4  is an exemplary diagram illustrating an augmented reality realizing method of an optical device according to an exemplary embodiment.  FIG. 5  is an exploded perspective view showing an example of the first lens and the reflectors of  FIG. 3 .  FIG. 6  is a plan view showing an example of the first lens of  FIG. 3 .  FIG. 7  is a front view showing an example of the first lens of  FIG. 3 .  FIG. 8  is a side view showing an example taken along a sectional line I-I′ of  FIG. 6 .  FIG. 9  is a side view showing an example taken along a sectional line II-II′ of  FIG. 6 .  FIG. 10  is a side view showing an example taken along a sectional line III-III′ of  FIG. 7 .  FIG. 11  is a side view showing an example taken along a sectional line IV-IV′ of  FIG. 7 . 
       FIG. 4  shows the first lens  110 , the first display device  210  and the first convex lens  310  as viewed from the left side of  FIG. 3 . Accordingly, among the first to fifth reflectors  411 ,  412 ,  413 ,  414 , and  415 , only the first reflector  411  and the third reflector  413  are illustrated.  FIG. 6  shows the first lens  110  in a top view.  FIG. 7  shows the first lens  110  in a top and side view. 
     Referring to  FIGS. 3, 4, 5, 6, 7, 8, 9, 10, and 11 , the first lens  110  may include a first lens portion  111 , a second lens portion  112  and an adhesive  113 . 
     The first lens portion  111  may include a first curved surface CS 1  having a concave curved surface with a first curvature, a first lower surface BSS 1  having a rectangular shape, a first left surface LSS 1  and a first right surface RSS 1  having a trapezoidal shape, a first upper surface US 1  sharing a first side of a curved line with the first curved surface CS 1 , and a lower surface BS 1  sharing a second side of a curved line with the first curved surface CS 1 . The first curved surface CS 1  may be a curved surface which is concave toward the lower side surface of the first lens portion  111 . 
     The second lens portion  112  may include a second curved surface CS 2  having a convex curved surface with a second curvature, a second upper surface USS 2  having a rectangular shape, a second left surface LSS 2  and a second right surface RSS 2  having a trapezoidal shape, a second upper surface US 2  sharing a first side of a curve line with the second curved surface CS 2 , and a lower surface BS 2  sharing a second side of a curved line with the second curved surface CS 2 . The second curved surface CS 2  may be a curved surface which is convex toward the first curved surface CS 1  of the first lens portion  111 . 
     The adhesive  113  is disposed between the first curved surface CS 1  of the first lens portion  111  and the second curved surface CS 2  of the second lens portion  112 . The first curved surface CS 1  of the first lens portion  111  and the second curved surface CS 2  of the second lens portion  112  may be bonded to each other. The adhesive  113  may be an optically clear resin (OCR) or an optically clear adhesive (OCA). 
     The refractive index of the first lens portion  111  may be substantially equal to the refractive index of the second lens portion  112 . In order to minimize an influence of the adhesive  113  causing refraction and reflection of the light of the first display device  210  provided to the first lens  110 , it may be designed to match the refractive index of the adhesive  113  with the refractive index of the first lens portion  111  and the refractive index of the second lens portion  112 . In this case, it is preferable that the refractive index of the adhesive  113  is substantially equal to the refractive index of the first lens portion  111  and the refractive index of the second lens portion  112 . However, a difference between the refractive index of the adhesive  113  and the refractive index of the first lens portion  111  and a difference between the refractive index of the adhesive  113  and the refractive index of the second lens portion  112  may be less than or equal to 0.1. 
     The first to fifth reflectors  411 ,  412 ,  413 ,  414 , and  415  may be disposed on the first curved surface CS 1  of the first lens portion  111 . The first to fifth reflectors  411 ,  412 ,  413 ,  414 , and  415  may be formed by depositing metal such as silver (Ag) having high reflectivity on the first curved surface CS 1  of the first lens portion  111 . Since the first curved surface CS 1  is formed as a concave curved surface with the first curvature, the reflecting surface of each of the first to fifth reflectors  411 ,  412 ,  413 ,  414 , and  415  may be formed as a concave curved surface with a curvature. 
     Since the first to fifth reflectors  411 ,  412 ,  413 ,  414 , and  415  are disposed on the first curved surface CS 1  of the first lens portion  111 , the curvature of the reflecting surface of the first reflector  411 , the curvature of the reflecting surface of the second reflector  412 , the curvature of the reflecting surface of the third reflector  413 , the curvature of the reflecting surface of the fourth reflector  414 , and the curvature of the reflecting surface of the fifth reflector  415  may be substantially the same. Further, since the first to fifth reflectors  411 ,  412 ,  413 ,  414 , and  415  are thinly deposited on the first curved surface CS 1  of the first lens portion  111 , the curvature of the reflecting surface of the first reflector  411 , the curvature of the reflecting surface of the second reflector  412 , the curvature of the reflecting surface of the third reflector  413 , the curvature of the reflecting surface of the fourth reflector  414 , and the curvature of the reflecting surface of the fifth reflector  415  may be substantially the same as the first curvature of the first curved surface CS 1 . 
     As shown in  FIG. 4 , after a virtual image IM displayed by the first display device  210  is condensed by the first convex lens  310  and provided to the first to fifth reflectors  411 ,  412 ,  413 ,  414 , and  415 , it may be reflected by the first to fifth reflectors  411 ,  412 ,  413 ,  414 , and  415  and emitted from an exit surface OS of the first lens  110  as an image B. The virtual image IM reflected by the first to fifth reflectors  411 ,  412 ,  413 ,  414 , and  415  may be emitted from the exit surface OS of the first lens  110  and formed as one point on the retina of the user&#39;s right eye RE. Therefore, even if the user does not move the focus adjusted to object A corresponding to the real image, the user can view both the object A corresponding to the real image and the virtual image IM as an image B. 
     Since the reflecting surface of each of the first to fifth reflectors  411 ,  412 ,  413 ,  414 , and  415  is formed as concave curved surface having a curvature, the image of the first display device  210  reflected by each of the first to fifth reflectors  411 ,  412 ,  413 ,  414 , and  415  may have a predetermined focal length. The distance at which the image of the first display device  210  is viewed may be determined by the first convex lens  310  and each of the first to fifth reflectors  411 ,  412 ,  413 ,  414 , and  415 . 
     First, the distance at which the image of the first display device  210  is viewed, which is determined by the first convex lens  310 , can be calculated by Eq. 1: 
     
       
         
           
             
               
                 
                   
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     where f1 is a focal length of the first convex lens  310 , a1 is a distance between the first convex lens  310  and the first display device  210 , and b1 is a distance at which the image of the first display device  210  is viewed by the first convex lens  310 . 
     In this case, the distance at which the image of the first display device  210  is viewed, which is determined by the first reflector  411 , can be calculated by Eq. 2: 
     
       
         
           
             
               
                 
                   
                     
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                   Eq 
                   . 
                   
                       
                   
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     where f2 is a focal length of the first reflector  411 , b1 is a distance at which the image of the first display device  210  is viewed by the first convex lens  310 , c1 is a distance between the first convex lens  310  and the first reflector  411 , and b2 is a distance at which the image of the first display device  210  is viewed by the first convex lens  310  and the first reflector  411 . 
     When b2 is substantially equal to the optical distance from the first reflector  411  to the retina of the user&#39;s right eye RE, the image of the first display device  210  may be formed on the retina of the user&#39;s right eye RE by the first convex lens  310  and the first reflector  411 . Therefore, as shown in  FIG. 4 , even if the user does not move the focus adjusted to the object A corresponding to the real image, the user can view both the object A corresponding to the real image and the virtual image IM. 
     Further, since b2 may be changed by the focal length f1 of the first convex lens  310  and the focal length f2 of the first reflector  411 , by adjusting the focal length f1 of the first convex lens  310  and the focal length f2 of the first reflector  411 , b2 can be adjusted to the optical distance from the first reflector  411  to the retina of the user&#39;s right eye RE. 
     The focal length f2 of the first reflector  411  may be determined according to the curvature of the reflecting surface of the first reflector  411 , and the curvature of the reflecting surface of the first reflector  411  may be determined by the curvature of the first curved surface CS 1 . Therefore, the focal length f2 of the first reflector  411  can be adjusted by changing the curvature of the first curved surface CS 1 . 
     Since the distance at which the image of the first display device  210  is viewed by the first convex lens  310  and each of the second to fifth reflectors  412 ,  413 ,  414 , and  415  is the same as the distance at which the image of the first display device  210  is viewed by the first convex lens  310  and the first reflector  411  described in conjunction with Eq. 1 and Eq. 2, a detailed description thereof will be omitted. Further, since the distance at which the image of the second display device  220  is viewed by the second convex lens  320  and each of the sixth to tenth reflectors  421 ,  422 ,  423 ,  424 , and  425  is the same as the distance at which the image of the first display device  210  is viewed by the first convex lens  310  and the first reflector  411  described in conjunction with Eq. 1 and Eq. 2, a detailed description thereof will be omitted. 
     As shown in  FIGS. 6, 7, and 10 , the first reflector  411  and the second reflector  412  may be arranged in parallel in the width direction (X-axis direction) of the first lens  110 . The first reflector  411  may be disposed closer to the left side surface, and the second reflector  412  may be disposed closer to the right side surface. 
     As shown in  FIGS. 6, 7, and 11 , the third reflector  413 , the fourth reflector  414 , and the fifth reflector  415  may be arranged in parallel in the width direction (X-axis direction) of the first lens  110 . The fourth reflector  414  may be disposed between the third reflector  413 , and the fourth reflector  414  in the width direction (X-axis direction) of the first lens  110 . The third reflector  413  may be disposed closer to the left side surface, and the fifth reflector  415  may be disposed closer to the right side surface. 
     As shown in  FIGS. 6, 7, 8, and 9 , each of the first reflector  411  and the second reflector  412  may not be arranged in parallel with any one of the third reflector  413 , the fourth reflector  414 , and the fifth reflector  415  in the height direction (Y-axis direction) of the first lens  110 . In this case, each of the first reflector  411  and the second reflector  412  may not overlap at all with any one of the third reflector  413 , the fourth reflector  414 , and the fifth reflector  415  in the height direction (Y-axis direction) of the first lens  110 . Alternatively, each of the first reflector  411  and the second reflector  412  may partially overlap any one of the third reflector  413 , the fourth reflector  414 , and the fifth reflector  415  in the height direction (Y-axis direction) of the first lens  110 . 
     A first spacer  510  for maintaining a distance between the first display device  210  and the first convex lens  310  may be disposed between the first display device  210  and the first convex lens  310 . A second spacer  520  for maintaining a distance between the first convex lens  310  and the first lens  110  may be disposed between the first convex lens  310  and the first side surface of the first lens  110 . 
     Meanwhile, the first display device  210 , the second display device  220 , the second convex lens  320  and the sixth to tenth reflectors  421 ,  422 ,  423 ,  424 , and  425  may be implemented in substantially the same manner as the first lens  110 , the first display device  210 , the first convex lens  310  and the first to fifth reflectors  411 ,  412 ,  413 ,  414 , and  415  described with reference to  FIGS. 3, 4, 5, 6, 7, 8, 9, 10, and 11 . Thus, a description of the first display device  210 , the second display device  220 , the second convex lens  320  and the sixth to tenth reflectors  421 ,  422 ,  423 ,  424 , and  425  will be omitted. 
     According to the exemplary embodiment shown in  FIGS. 3, 4, 5, 6, 7, 8, 9, 10 , and  11 , after an image of a display device is refracted through a convex lens, it is reflected by a reflector having a concave curved surface and provided to the user&#39;s eyes. Thus, the distance at which the image of the display device is viewed may be determined by the focal length of the convex lens and the focal length of the reflector. Therefore, even if the focal length of the convex lens is not reduced, the image of the display device can be provided to the user&#39;s eyes. 
     In addition, it is possible to prevent or reduce a decrease in image quality of a virtual image viewed by the user due to the chromatic aberration of the convex lens having a short focal length. 
       FIGS. 12, 13, and 14  show examples of a virtual image displayed on the first display device, which is displayed to the user according to the curvature of the first curved surface of the first lens. 
       FIG. 12  shows a virtual image of the first display device  210  displayed to the user when the curvature K of the first curved surface CS 1  of the first lens  110  is 0.015 mm −1 .  FIG. 13  shows a virtual image of the first display device  210  displayed to the user when the curvature K of the first curved surface CS 1  of the first lens  110  is 0.01 mm −1 .  FIG. 14  shows a virtual image of the first display device  210  displayed to the user when the curvature K of the first curved surface CS 1  of the first lens  110  is 0.006 mm −1 . 
     In the examples of  FIGS. 12, 13, and 14 , twenty-one reflectors were disposed on the first curved surface CS 1  of the first lens  110 , and a virtual image of the first display device  210  was reflected by the twenty-one reflectors to provide virtual images to the user as shown in  FIGS. 12, 13, and 14 . 
     When the curvature K of the first curved surface CS 1  is 0.015 mm −1  as shown in  FIG. 12 , since the virtual image of the first display device  210  is not focused on the user&#39;s retina, the virtual image is blurred. 
     When the curvature K of the first curved surface CS 1  is 0.01 mm −1  as shown in  FIG. 13 , since the virtual image of the first display device  210  is focused near the user&#39;s retina, the user can view the virtual image of the first display device  210  to some extent. 
     When the curvature K of the first curved surface CS 1  is 0.006 mm −1  as shown in  FIG. 14 , since the virtual image of the first display device  210  is focused on the user&#39;s retina, the user can properly view the virtual image of the first display device  210 . 
     Since the first to fifth reflectors  411 ,  412 ,  413 ,  414 , and  415  are disposed on the first curved surface CS 1  of the first lens  110 , the curvature of the reflecting surface of each of the first to fifth reflectors  411 ,  412 ,  413 ,  414 , and  415  depends on the curvature K of the first curved surface CS 1  of the first lens  110 . Further, the distance at which the virtual image of the first display device  210  is viewed may be determined by the first lens  110  and each of the first to fifth reflectors  411 ,  412 ,  413 ,  414 , and  415 . Therefore, the curvature K of the first curved surface CS 1  of the first lens  110  according to the focal length of the first convex lens  310  can be optimally determined through a preliminary experiment. 
       FIG. 15  is a plan view showing an example of the first display device of  FIG. 3 . 
     Referring to  FIG. 15 , the first display panel  211  of the first display device  210  may include a display area DA, a pad area PA, a scan driving circuit portion SDC and an integrated driving circuit portion DDC. 
     The display area DA may include data lines DL, scan lines SL and pixels PX. As shown in  FIG. 15 , the data lines DL may be arranged in the width direction (X-axis direction) of the first lens  110  and the scan lines SL may be arranged in the thickness direction (Z-axis direction) of the first lens  110 . The pixels PX may be arranged in regions defined by the data lines DL and the scan lines SL. For example, the pixels PX may be arranged in the intersection regions of the data lines DL and the scan lines SL. A detailed description of the pixels PX of the display area DA will be given later with reference to  FIG. 16 . 
     The pad area PA includes routing lines RL connected to the integrated driving circuit portion DDC and pads DP connected to the routing lines RL. The pads DP may be electrically connected to the first circuit board  212 . The first circuit board  212  may be attached onto the pads DP using an anisotropic conductive film. 
     The scan driving circuit portion SDC may be disposed on the first side of the display area DA. The scan driving circuit portion SDC may be disposed adjacent to the long side of the display area DA. The scan driving circuit portion SDC is connected to the scan lines SL of the display area DA. The scan driving circuit portion SDC may receive a scan control signal from the integrated driving circuit portion DDC, generate scan signals according to a scan control signal, and sequentially apply the scan signals to the scan lines SL. 
     The scan driving circuit portion SDC may include thin film transistors as switch elements. In this case, the thin film transistors of the scan driving circuit portion SDC may be formed simultaneously with the thin film transistors of the pixels PX of the display area DA. 
     The integrated driving circuit portion DDC may be disposed on the second side of the display area DA. The integrated driving circuit portion DDC may be disposed adjacent to the short side of the display area DA. The integrated driving circuit portion DDC may be disposed in the pad area PA. Alternatively, the integrated driving circuit portion DDC may be disposed on the first circuit board  212 . The integrated driving circuit portion DDC may be formed of an integrated circuit. 
     The integrated driving circuit portion DDC receives the timing signals and the video data through the routing lines RL. The integrated driving circuit portion DDC may generate a scan control signal from the timing signals and output the scan control signal to the scan driving circuit portion SDC. The integrated driving circuit portion DDC may generate a data control signal from the timing signals. The integrated driving circuit portion DDC may generate and apply data voltages to the data lines DL during a period in which the scan signals are applied according to the data control signal and the video data. 
       FIG. 16  is a cross-sectional view specifically showing the display area of the first display panel of  FIG. 14 . 
     Referring to  FIG. 16 , the display area DA of the first display device  210  may include a substrate  1100 , a thin film transistor layer  1230 , a light emitting element layer  1240 , and a thin film encapsulation layer  1300 . 
     The thin film transistor layer  1230  is formed on the substrate  1100 . The thin film transistor layer  1230  includes thin film transistors  1235 , a gate insulating film  1236 , an interlayer insulating film  1237 , a protective film  1238 , and a planarization film  1239 . 
     A buffer film may be formed on the substrate  1100 . The buffer film may be formed on the substrate  1100  to protect the thin film transistors  1235  and light emitting elements from moisture penetrating through the substrate  1100  susceptible to moisture permeation. The buffer film may include a plurality of alternately stacked inorganic films. For example, the buffer film may be formed of multiple films in which one or more inorganic films of a silicon oxide film (SiOx), a silicon nitride film (SiNx), and SiON are alternately stacked. The buffer film may be omitted. 
     The thin film transistors  1235  are formed on the buffer film. Each of the thin film transistors  1235  includes an active layer  1231 , a gate electrode  1232 , a source electrode  1233  and a drain electrode  1234 . Although  FIG. 3  illustrates that each of the thin film transistors  1235  is formed by a top gate method in which the gate electrode  1232  is formed above the active layer  1231 , the present disclosure is not limited thereto. That is, each of the thin film transistors  1235  may be formed by a bottom gate method in which the gate electrode  1232  is located below the active layer  1231  or a double gate method in which the gate electrode  1232  is located both above and below the active layer  1231 . 
     The active layer  1231  is formed on the buffer film. The active layer  1231  may be formed of a silicon-based semiconductor material or an oxide-based semiconductor material. A light shielding layer for shielding external light incident on the active layer  1231  may be formed between the buffer film and the active layer  1231 . 
     The gate insulating film  1236  may be formed on the active layer  1231 . The gate insulating film  1236  may be formed of an inorganic film, for example, a silicon oxide film (SiOx), a silicon nitride film (SiNx), or a multilayer film thereof. 
     The gate electrode  1232  and a gate line may be formed on the gate insulating film  1236 . The gate electrode  1232  and the gate line may be formed as a single layer or multiple layers made of any one of molybdenum (Mo), aluminum (Al), chromium (Cr), gold (Au), titanium (Ti), nickel (Ni), neodymium (Nd) and copper (Cu) or an alloy thereof. 
     The interlayer insulating film  1237  may be formed on the gate electrode  1232  and the gate line. The interlayer insulating film  1237  may be formed of an inorganic film, for example, a silicon oxide film (SiOx), a silicon nitride film (SiNx), or a multilayer film thereof. 
     The source electrode  1233 , the drain electrode  1234  and a data line may be formed on the interlayer insulating film  1237 . Each of the source electrode  1233  and the drain electrode  1234  may be connected to the active layer  1231  via a contact hole passing through the gate insulating film  1236  and the interlayer insulating film  1237 . The source electrode  1233 , the drain electrode  1234  and the data line may be formed as a single layer or multiple layers made of any one of molybdenum (Mo), aluminum (Al), chromium (Cr), gold (Au), titanium (Ti), nickel (Ni), neodymium (Nd) and copper (Cu) or an alloy thereof. 
     The protective film  1238  for insulating the thin film transistor  1235  may be formed on the source electrode  1233 , the drain electrode  1234  and the data line. The protective film  1238  may be formed of an inorganic film, for example, a silicon oxide film (SiOx), a silicon nitride film (SiNx), or a multilayer film thereof. 
     The planarization film  1239  may be formed on the protective film  1238  to flatten a step due to the thin film transistors  1235 . The planarization film  1239  may be formed of an organic film such as an acryl resin, an epoxy resin, a phenolic resin, a polyamide resin, or a polyimide resin. 
     The light emitting element layer  1240  is formed on the thin film transistor layer  1230 . The light emitting element layer  1240  includes light emitting elements and a pixel defining layer  1244 . 
     The light emitting elements and the pixel defining layer  1244  are formed on the planarization film  1239 . The light emitting element may be an organic light emitting device. In this case, the light emitting element may include an anode electrode  1241 , light emitting layers  1242  and a cathode electrode  1243 . 
     The anode electrode  1241  may be formed on the planarization film  1239 . The anode electrode  1241  may be connected to the source electrode  1233  of the thin film transistor  1235  via the contact hole passing through the protective film  1238  and the planarization film  1239 . 
     The pixel defining layer  1244  may be formed to cover the edge of the anode electrode  1241  on the planarization film  1239  to partition the pixels. That is, the pixel defining layer  1244  serves as a pixel defining layer for defining pixels. Each of the pixels represents a region where the anode electrode  1241 , the light emitting layer  1242  and the cathode electrode  1243  are stacked sequentially and holes from the anode electrode  1241  and electrons from the cathode electrode  1243  are coupled to each other in the light emitting layer  1242  to emit light. 
     The light emitting layer  1242  is formed on the anode electrode  1241  and the pixel defining layer  1244 . The light emitting layer  1242  may be an organic light emitting layer. The light emitting layer  1242  may emit one of red light, green light and blue light. The peak wavelength range of red light may be about 620 nm to 750 nm, and the peak wavelength range of green light may be about 495 nm to 570 nm. Further, the peak wavelength range of blue light may be about 450 nm to 495 nm. Alternatively, the light emitting layer  1242  may be a white light emitting layer that emits white light. In this case, the red light emitting layer, the green light emitting layer, and the blue light emitting layer may have a laminated form, and may be a common layer formed commonly to the pixels. In this case, the display device  200  may further include a separate color filter for displaying a red, green or blue color. 
     The light emitting layer  1242  may include a hole transporting layer, a light emitting layer, and an electron transporting layer. In addition, the light emitting layer  1242  may be formed in a tandem structure of two or more stacks, in which case a charge generating layer may be formed between the stacks. 
     The cathode electrode  1243  is formed on the light emitting layer  1242 . The cathode electrode  1243  may be formed to cover the light emitting layer  1242 . The cathode electrode  1243  may be a common layer formed commonly to the pixels. 
     In a case where the light emitting element layer  1240  is formed by a top emission method in which light is emitted upward, the anode electrode  1241  may be formed of a metal material having high reflectivity to have a laminated structure of aluminum and titanium (Ti/Al/Ti), a laminated structure of aluminum and ITO (ITO/AUITO), an APC alloy, and a laminated structure of an APC alloy and ITO (ITO/APC/ITO). The APC alloy is an alloy of silver (Ag), palladium (Pd) and copper (Cu). Further, the cathode electrode  1243  may be formed of a transparent conductive material (TCO) such as ITO or IZO that can transmit light or a semi-transmissive conductive material such as magnesium (Mg), silver (Ag), or an alloy of magnesium (Mg) and silver (Ag). When the cathode electrode  1243  is formed of a semi-transmissive conductive material, the light emission efficiency can be increased by microcavity. 
     In a case where the light emitting element layer  1240  is formed by a bottom emission method in which light is emitted downward, the anode electrode  1241  may be formed of a transparent conductive material (TCO) such as ITO or IZO or a semi-transmissive conductive material such as magnesium (Mg), silver (Ag), or an alloy of magnesium (Mg) and silver (Ag). The cathode electrode  1243  may be formed of a metal material having high reflectivity to have a laminated structure of aluminum and titanium (Ti/Al/Ti), a laminated structure of aluminum and ITO (ITO/Al/ITO), an APC alloy, and a laminated structure of an APC alloy and ITO (ITO/APC/ITO). When the anode electrode  1241  is formed of a semi-transmissive conductive material, the light emission efficiency can be increased by microcavity. 
     The thin film encapsulation layer  1300  is formed on the light emitting element layer  1240 . The thin film encapsulation layer  1300  prevents or suppresses oxygen or moisture from permeating the light emitting layer  1242  and the cathode electrode  1243 . To this end, the thin film encapsulation layer  1300  may comprise at least one inorganic film. The inorganic film may be formed of silicon nitride, aluminum nitride, zirconium nitride, titanium nitride, hafnium nitride, tantalum nitride, silicon oxide, aluminum oxide, or titanium oxide. Further, the thin film encapsulation layer  1300  may further include at least one organic film. The organic film may be formed to have a thickness sufficient to prevent or suppress particles from penetrating the thin film encapsulation layer  1300  and being injected into the light emitting layer  1242  and the cathode electrode  1243 . The organic film may include any one of epoxy, acrylate or urethane acrylate. Instead of the thin film encapsulation layer  1300 , an encapsulation substrate may be disposed on the light emitting element layer  1240 . 
     According to the exemplary embodiments of the present disclosure, an image of a display device is refracted through a convex lens and reflected by a reflector having a concave curved surface to be provided to the user&#39;s eyes. Thus, the distance at which the image of the display device is viewed may be determined by the focal length of the convex lens and the focal length of the reflector. Therefore, without reducing the focal length of the convex lens, the image of the display device can be appropriately provided to the user&#39;s eyes. In addition, it is possible to prevent or reduce a decrease in image quality of a virtual image viewed by the user due to the chromatic aberration of the convex lens having a short focal length. 
     Although certain exemplary embodiments and implementations have been described herein, other exemplary embodiments and modifications will be apparent from this is description. Accordingly, the inventive concepts are not limited to such embodiments, but rather to the broader scope of the appended claims and various obvious modifications and equivalent arrangements as would be apparent to a person of ordinary skill in the art.