See-through type display apparatus and electronic device including the same

Abstract

The disclosed projection-type display device includes an image projector that outputs image light; a waveguide that transmits the image light output from the image projector to the user's field of vision; and a first lens with negative refractive power and a second lens with positive refractive power, respectively disposed on both sides of the waveguide. The first lens and the second lens each include one or more meta-lenses and are configured to operate as lenses with almost no chromatic aberration, thereby enabling good image quality and the realization of a thin optical system.

Description

Technology Field

[0001] The disclosed embodiments relate to a transparent display device and an electronic device including the same. Background Technology

[0002] Recently, there has been growing interest in ultra-small display devices that can be applied as wearable display devices for implementing virtual reality devices, augmented reality devices, and the like.

[0003] Methods to lighten and thin ultra-small display devices while maintaining the image quality delivered to the user's eyes are continuously being sought, and as an example for this, light waveguide-based optical systems are being utilized. The problem to be solved

[0004] A transparent display device having a thin and convenient structure for wearing is provided. means of solving the problem

[0005] According to an embodiment, a projection display device is provided, comprising: a projection projector that outputs image light; a waveguide that transmits the image light output from the projection projector to a user's field of vision, the waveguide having a first surface on which the image light is output and a second surface facing the first surface; a first lens disposed on the first surface, having a negative refractive power and including one or more meta-lenses; and a second lens disposed on the second surface, having a positive refractive power.

[0006] The first lens may include: a first meta lens disposed on the first surface and having a negative refractive power; a second meta lens disposed at a first distance from the first meta lens and having a positive refractive power; and a third meta lens disposed at a second distance from the second meta lens and having a negative refractive power.

[0007] The first lens may further include a first spacer disposed between the first meta lens and the second meta lens and having a thickness corresponding to the first distance; and a second spacer disposed between the second meta lens and the third meta lens and having a thickness corresponding to the second distance.

[0008] The first spacer and the second spacer may have the same refractive index and the same thickness.

[0009] The first lens may include: a first meta lens disposed on the first surface and having a positive refractive power; a second meta lens disposed at a first distance from the first meta lens and having a negative refractive power; and a third meta lens disposed at a second distance from the second meta lens and having a positive refractive power.

[0010] The second lens above may be a refractive lens having one surface that is a convex curve.

[0011] The second lens may include one or more meta lenses.

[0012] The second lens may include: a first meta lens having a positive refractive power; a second meta lens having a negative refractive power and positioned at a first distance from the first meta lens; and a third meta lens having a positive refractive power and positioned at a second distance from the second meta lens.

[0013] The second lens may further include a first spacer disposed between the first meta lens and the second meta lens and having a thickness corresponding to the first distance; and a second spacer disposed between the second meta lens and the third meta lens and having a thickness corresponding to the second distance.

[0014] The first spacer and the second spacer may have the same refractive index and the same thickness.

[0015] The above first distance and the above second distance are d min There is an issue, and d min ... is as follows, where f is the focal length of the second lens, D is the effective diameter of the second lens, and n g is the refractive index, θ of the first spacer and the second spacer. max is the maximum deflection angle of the incident light by the first meta-lens.

[0016]

[0017] The second lens may further include a blocking member that blocks light incident on the second lens from passing through the center of the second meta-lens.

[0018] The blocking member may be positioned at the center of the first meta-lens.

[0019] The above blocking member can be positioned at the center of the second meta-lens.

[0020] The above blocking member has a diameter D 0min It could be more than that, D 0min is as follows, where f is the focal length of the second lens, D is the effective diameter of the second lens, and n g is the refractive index of the first spacer and the second spacer, θ max is the maximum deflection angle of the incident light by the first meta-lens.

[0021]

[0022] The absolute value of the negative refractive power exhibited by the first lens may differ from the absolute value of the positive refractive power exhibited by the second lens.

[0023] The above-described transparent display device may further include a removable vision correction lens disposed adjacent to the first lens.

[0024] The above-mentioned vision correction lens may be a meta lens.

[0025] According to an embodiment, an electronic device is provided comprising: any one of the above-described transparent display devices; and a processor that controls the transparent display device to output an additional image suitable for the environment in which the user is looking.

[0026] The above-described transparent display device may be an eye-wearable device. Effects of the invention

[0027] The above-described transparent display device is based on a waveguide and a meta-lens, and can implement a thin optical system with almost no chromatic aberration.

[0028] The above-described transparent display device has a structure that is convenient for application to wearable devices and can be applied to various electronic devices such as augmented reality devices. Brief explanation of the drawing

[0029] FIG. 1 is a conceptual diagram showing the schematic configuration of a transparent display device according to an embodiment. FIG. 2 is a conceptual diagram showing the schematic configuration of a transparent display device according to a comparative example. FIG. 3 is a conceptual diagram showing the schematic structure of a first lens provided in a projection-type display device according to an embodiment and an optical path showing a negative refractive power without chromatic aberration. Figure 4 is a graph exemplarily showing the phase profile of three meta-lenses forming the first lens of Figure 3. FIG. 5 is a conceptual diagram showing the schematic structure of a first lens of another example provided in a projection-type display device according to an embodiment and an optical path showing a negative refractive power without chromatic aberration. FIG. 6 shows the schematic structure of a second lens provided in a transparent display device according to an embodiment. Figure 7 is a graph exemplifying the phase profile of the three meta-lenses forming the second lens of Figure 6. Figure 8 is a graph showing the relationship between the thickness of the spacer and the focal length for various maximum deflection angles by the first metalens in the second lens of Figure 6. FIG. 9 is a graph showing the relationship between the diameter of the blocking member and the focal length for various maximum deflection angles by the first metalens in the second lens of FIG. 6. FIG. 10 shows the schematic structure of a second lens of another example provided in a transparent display device according to an embodiment. FIG. 11 is a plan view showing the schematic structure of a meta-lens provided in a transparent display device according to an embodiment. FIGS. 12 and FIGS. 13 are cross-sectional views showing an exemplary cross-sectional structure of the meta-lens of FIG. 11. FIG. 14 shows the schematic structure of a transparent display device according to another embodiment. FIG. 15 shows the schematic structure of a transparent display device according to another embodiment. FIG. 16 is a conceptual diagram showing the schematic structure of an augmented reality device according to an embodiment. FIGS. 17 and 18 show the external appearance of various electronic devices employing a transparent display device according to an embodiment. FIG. 19 is a block diagram of an electronic device according to an embodiment. Specific details for implementing the invention

[0030] Hereinafter, embodiments will be described in detail with reference to the attached drawings. The described embodiments are merely illustrative, and various modifications are possible from these embodiments. 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.

[0031] In the following, terms described as "upper" or "upper" may include not only those directly above in contact, but also those above without contact.

[0032] Terms such as first, second, etc., may be used to describe various components, but are used solely for the purpose of distinguishing one component from another. These terms do not limit the difference in the material or structure of the components.

[0033] A singular expression includes a plural expression unless the context clearly indicates otherwise. Furthermore, when a part is said to "include" a certain component, this means that, unless specifically stated otherwise, it does not exclude other components but may include additional components.

[0034] 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.

[0035] The use of the term “above” and similar descriptive terms may apply to both the singular and plural forms.

[0036] 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.

[0037] FIG. 1 is a conceptual diagram showing the schematic configuration of a transparent display device according to an embodiment.

[0038] Referring to FIG. 1, a projection display device (1000) includes an image projector (100) that outputs image light (L1), a waveguide (400) that transmits image light (L1) to the user's field of vision, a first lens (600) having negative refractive power disposed adjacent to a first surface (400a) which is the light-emitting surface of the waveguide (400), and a second lens (200) having positive refractive power disposed adjacent to a second surface (400b) facing the first surface (400a).

[0039] A transparent display device (1000) is a device that combines video light (L1) provided by a video projector (100) and ambient light (L2) containing a real environment in front of the user and provides it to the user. Through the transparent display device (1000), the user can view the first image (I1) provided by the video projector (100) and the second image (I2), which is the real environment, together.

[0040] The waveguide (400) acts as an optical coupler that combines image light (L1) and ambient light (L2) and provides them to the user's eye. It is transparent to the ambient light (L2) incident parallel to the first direction (Z direction) toward the user's field of vision, and changes the path of the image light (L1) incident from a direction different from the first direction to a direction parallel to the first direction (Z direction) so that it faces the user's field of vision.

[0041] The image light (L1) provided by the image projector (100) travels through the inside of the waveguide (400) and is emitted through the first surface (400a), and is transmitted to the user's field of vision through the first lens (600). At this time, due to the first lens (600) having negative refractive power, the user perceives the first image (I1) as coming from a predetermined virtual plane, that is, at the focal length (F) position of the first lens (600).

[0042] In order for the ambient light (L2) containing the second image (I2) of the real image in front of the user to be transmitted to the user's field of vision without the action of refractive power, the second lens (200) may have a positive refractive power of a size that cancels out the negative refractive power of the first lens (600).

[0043] Alternatively, the absolute value of the negative refractive power of the first lens (600) may be greater than the absolute value of the positive refractive power of the second lens (200), and accordingly, it may also function as a lens that corrects the vision of a user with myopia.

[0044] Alternatively, the absolute value of the negative refractive power of the first lens (600) may be smaller than the absolute value of the positive refractive power of the second lens (200), and accordingly, it may also function as a lens that corrects the vision of a hyperopic user.

[0045] In other words, the combined refractive power of the first lens (600) and the second lens (200) can be set to have a desired negative value or a desired positive value suitable for the user's eyesight.

[0046] In the projection display device (1000) of the embodiment, the first lens (600) and the second lens (200) may each include one or more meta-lenses. A meta-lens is a lens that exhibits a refractive power effect by implementing a phase distribution capable of deflecting incident light at different angles depending on the position using a plurality of nanostructures having shape dimensions of a sub-wavelength. The sub-wavelength refers to a value smaller than the center wavelength of the wavelength band of the image light (L1) emitted from the image projector (100), which is the operating wavelength of the projection display device (1000). Light incident on a plurality of nano-nanostructures that exhibit a difference in refractive index from surrounding materials undergoes a refractive index distribution according to the shape and arrangement of the nanostructures, and the phase is delayed. The degree of phase delay varies depending on the position representing the refractive index distribution, and accordingly, the shape of the wavefront connecting points with the same phase changes from before it is incident on the nanostructures, that is, the incident light is deflected. The meta-lenses included in the first lens (600) and the second lens (200) include a plurality of nanostructures of a shape and arrangement capable of implementing a phase distribution corresponding to the refractive power that each lens is intended to represent. The expression 'phase' used in the description refers to a relative phase, i.e., 'phase delay,' based on the position immediately after passing through the nanostructures, before experiencing the refractive index distribution formed by the nanostructures. An exemplary detailed structure of the first lens (600) and the second lens (200), and an exemplary detailed structure of the meta-lenses included in the first lens (600) and the second lens (200) will be described later.

[0047] These meta-lenses can have a very thin thickness compared to conventional refractive lenses that form refractive power by adjusting the curved shape, that is, the degree and form of concave or convexity, and can also be configured in detail to operate as nearly achromatic lenses with almost no chromatic aberration.

[0048] For example, looking at the comparative example of the transparent display device (1) illustrated in FIG. 2, the transparent display device (1) includes an image projector (100), a waveguide (40), and convex lenses (40) and concave lenses (60) respectively placed on both sides of the waveguide (40). A vision correction lens (70) having a curved surface may be further provided in the path of light coming from the concave lens (60) toward the user.

[0049] The thickness of the concave lens (60), convex lens (20), and vision correction lens (70) provided in the transparent display device (1) becomes thicker as the refractive power increases, as the refractive power is formed in a curved shape, and the total thickness (TH') can be several mm to several cm or more. Such thickness may be a factor that makes it uncomfortable to wear, for example, when the transparent display device (1) is implemented as a glasses-type device.

[0050] A transparent display device (1000) according to an embodiment includes a first lens (600) with negative refractive power and a second lens (200) with positive refractive power, which do not employ a physical curved shape. Additionally, the first lens (600) may also function as a vision correction lens, so that the total thickness (TH) can be reduced. For example, the thickness TH may be about 8 mm or less.

[0051] Again, referring to FIG. 1, we will examine the detailed configuration of the transparent display device (1000).

[0052] The image projector (100) includes a display element (not shown) that modulates light according to image information to be displayed to an observer to form image light, and one or more optical elements (not shown) that transmit the image light formed by the display element toward a waveguide (400).

[0053] The type of image formed by the display element provided in the image projector (100) is not particularly limited and may be, for example, a two-dimensional image or a three-dimensional image. The three-dimensional image may be, for example, a stereo image, a hologram image, a light field image, or an IP (integral photography) image, and may also include a multi-view or super multi-view type image.

[0054] The display element may include, for example, an LCoS (liquid crystal on silicon) element, an LCD (liquid crystal display) element, an OLED (organic light emitting diode) display element, and a DMD (digital micromirror device), and may also include next-generation display elements such as Micro LED and QD (quantum dot) LED. When the display element provided in the image projector (100) is a non-emissive element such as an LCD, a light source that provides light for forming an image to the display element may be further included.

[0055] The image projector (100) may be equipped with an optical element, such as a path switching member or a lens, to transmit the image light (L1) formed by the display element to the waveguide (400). For example, a beam splitter that changes the path of the image light (L1), a relay lens that magnifies or reduces the image light, a spatial filter for noise removal, etc., may be included, but is not limited thereto, and various known optical systems may be used.

[0056] The waveguide (400) is made of an optically transparent material and may be made of glass or transparent plastic having a refractive index greater than 1. Here, "transparent material" means a material through which image light (L1) formed by an image projector (100) can pass, and the transparency may not be 100% and may have a certain color.

[0057] The waveguide (400) includes a first surface (400a) and a second surface (400b) facing each other, and incident image light (L1) propagates inside the waveguide (400) while undergoing total reflection on the first surface (400a) and the second surface (400b). The waveguide (400) may be equipped with an input coupler (not shown) that inputs the image light (L1) at an angle that causes total reflection inside the waveguide (400), and an output coupler (not shown) that outputs the image light (L1) by breaking the total reflection condition occurring inside the waveguide (400), and the image light (L1) may be emitted through the first surface (400a) by the output coupler. The input coupler and output coupler may be formed at appropriate locations on the first surface (400a) and the second surface (400b) of the waveguide (400), and may be formed on different surfaces, or both may be formed on the first surface (400a), or both may be formed on the second surface (400b). In the drawing, the image light from the image projector (100) is shown as being incident on the side of the waveguide (400), but this is an illustration for convenience and is not limited thereto.

[0058] FIG. 3 is a conceptual diagram showing the schematic structure of a first lens provided in a projection-type display device according to an embodiment and an optical path showing negative refractive power without chromatic aberration, and FIG. 4 is a graph exemplarily showing the phase profile of each of the three metalens provided in the first lens of FIG. 3.

[0059] Referring to FIG. 3, the first lens (600) includes a first metalens (610), a second metalens (620), and a third metalens (630). The first metalens (610) and the second metalens (620) may be separated by a distance d1, and the second metalens (620) and the third metalens (630) may be separated by a distance d2. A first spacer (650) with a thickness d1 and a refractive index n1 may be placed between the first metalens (610) and the second metalens (620), and a second spacer (660) with a thickness d2 and a refractive index n2 may be placed between the second metalens (620) and the third metalens (630). d1 and d2 may be equal to each other, and n1 and n2 may be equal to each other. However, it is not limited thereto.

[0060] The first lens (600) utilizes three metalens that have chromatic aberration to achieve a negative refractive power that is almost achromatic. That is, the first metalens (610), the second metalens (620), and the third metalens (630) have chromatic aberration and each have a negative refractive power, a positive refractive power, and a negative refractive power, respectively.

[0061] Chromatic aberration occurs when the phase delay dispersion due to the nanostructures forming the metalens is zero, that is, when ∂φ / ∂λ is zero. The phase delays, φ1, φ2, and φ3 due to the first metalens (610), the second metalens (620), and the second metalens (630), respectively, may have a phase profile according to position as exemplified in FIG. 4. These phase profiles are identical regardless of wavelength, or have a form shifted by a constant between different wavelengths, that is, the phase delay dispersion is zero. Light incident on a metalens having chromatic aberration is deflected at different angles depending on the wavelength and emitted in different directions. The chromatic aberration exhibited by the metalens is a negative chromatic aberration in which the wavelength and focal length are inversely proportional, which is the opposite tendency to the positive chromatic aberration exhibited by a general refractive lens, which exhibits a focal length proportional to the wavelength.

[0062] Light incident on the first lens (600) passes through the first metalens (610) and is deflected by negative refractive power. At this time, the degree of deflection varies depending on the wavelength, and the light is separated into red light (R), green light (G), and blue light (B) and directed in different directions. The longer the wavelength, the greater the angle of deflection; that is, the angle of deflection is greatest for red light (R), followed by green light (G) and then blue light (B), in that order. The light separated in this way passes through the second metalens (620) and is subjected to positive refractive power, and then passes through the third metalens (630) and is subjected to negative refractive power. Even when passing through the second metalens (620), the deflection angle of the red light (R) is the largest, followed by the green light (G) and the blue light (B), and after being incident on the third metalens (630) at different angles of incidence, the red light (R), green light (G), and blue light (B) all face in the same direction after passing through the third metalens (630).

[0063] The details constituting the configuration of the first lens (600) of negative refractive power without chromatic aberration, as described in FIGS. 3 and 4, can be expressed as follows.

[0064]

[0065] Here, f1, f2, and f3 are the focal lengths of the first metalens (610), the second metalens (620), and the third metalens (630), respectively, d1=d2=d, and n1=n2=n g This is the case. F is the focal length of the first lens.

[0066]

[0067] φ1, φ2, and φ3 are phase delays caused by the first metalens (610), the second metalens (620), and the second metalens (630), respectively, and λ0 is the center wavelength of the operating wavelength band of the first lens (600).

[0068] Depending on the desired F value, f1, f2, and f3 can be determined from the above equations.

[0069] For example, F=-1m, d=1mm, n g If = 1.46, f1=-36.33mm, f2=18.85mm, f3=-36.33mm, or f1=37.70mm, f2=-18.17mm, f3=37.73mm.

[0070] From this, it can be seen that a negative refractive power without chromatic aberration can be realized with a refractive power combination different from that of Fig. 3.

[0071] FIG. 5 is a conceptual diagram showing the schematic structure of a first lens of another example provided in a projection-type display device according to an embodiment and an optical path showing a negative refractive power without chromatic aberration.

[0072] Referring to FIG. 5, the first lens (601) includes a first metalens (611), a second metalens (621), and a third metalens (631), each having chromatic aberration, and the first metalens (611), the second metalens (621), and the third metalens (631) each have positive refractive power, negative refractive power, and positive refractive power, respectively. The first metalens (611) and the second metalens (621) may be separated by a distance d1, and the second metalens (621) and the third metalens (631) may be separated by a distance d2. A first spacer (651) with thickness d1 and refractive index n1 may be placed between the first metalens (611) and the second metalens (621), and a second spacer (661) with thickness d2 and refractive index n2 may be placed between the second metalens (621) and the third metalens (631). d1 and d2 may be equal to each other, and n1 and n2 may be equal to each other. However, it is not limited thereto.

[0073] The first lens (601) of FIG. 5 differs from the first lens (600) of FIG. 3 in the refractive power of each of the first metalens (611), the second metalens (621), and the third metalens (631), and with this configuration, the first lens (601) exhibits a negative refractive power with almost no chromatic aberration, similar to the first lens (600) of FIG. 3.

[0074] Light incident on the first lens (601) passes through the first metalens (611) and is deflected by positive refractive power. At this time, the degree of deflection varies depending on the wavelength, causing the light to be separated into red light (R), green light (G), and blue light (B) and directed in different directions. The longer the wavelength, the greater the angle of deflection; that is, the angle of deflection is largest for red light (R), followed by green light (G) and then blue light (B), in that order. The light separated in this way passes through the second metalens (621) and is subjected to negative refractive power, and then passes through the third metalens (631) and is subjected to positive refractive power. Even when passing through the second metalens (621), the magnitude of the deflection angle is greatest for red light (R), and decreases in the order of green light (G) and blue light (B). After being incident on the third metalens (631) at different angles of incidence, the red light (R), green light (G), and blue light (B) all face in the same direction after passing through the third metalens (631).

[0075] FIG. 6 shows a schematic structure of a second lens provided in a transparent display device according to an embodiment. FIG. 7 is a graph showing the phase of three meta-lenses forming the second lens of FIG. 6.

[0076] The second lens (200) is a lens having positive refractive power with almost no chromatic aberration. The second lens (200) includes a first metalens (210), a second metalens (220), and a third metalens (230). The first metalens (210), the second metalens (220), and the third metalens (230) may each have positive refractive power, negative refractive power, and positive refractive power, respectively. The first metalens (210) and the second metalens (220) may be separated by a distance d1, and the second metalens (220) and the third metalens (230) may be separated by a distance d2. A first spacer (250) with thickness d1 and refractive index n1 may be placed between the first metalens (210) and the second metalens (220), and a second spacer (230) with thickness d2 and refractive index n2 may be placed between the second metalens (220) and the third metalens (230). d1 and d2 may be equal to each other, and n1 and n2 may be equal to each other. However, it is not limited thereto.

[0077] A blocking member (280) may be further provided in the second lens (200). The position of the blocking member (280) is not particularly limited as long as it can block light incident on the second lens (200) from passing through the center of the second metalens (220). The blocking member (280) can block light incident on the second lens (200) from passing through the center of the first metalens (210), the second metalens (220), and the third metalens (230). The reason for the placement of the blocking member (280) is that, as shown in FIG. 7, there exists a singular point at the center of each of the first metalens (210), the second metalens (220), and the third metalens (230) where the sign and magnitude of the refractive power change abruptly, which can disrupt the continuous chromatic aberration optical path conditions and create scattered light noise. As described, the blocking member (280) may be positioned at the center of the first metalens (210).

[0078] The phase profiles of the first metalens (210), the second metalens (220), and the third metalens (230) can be determined so that the second lens (200) has a refractive power with almost no chromatic aberration.

[0079] The chromatic aberration of the second lens (200) is related to the phase delay dispersion, i.e., dФ / dλ, that the second lens (200) exhibits, and for the achromatic property, a phase delay dispersion profile of a predetermined requirement must be satisfied.

[0080] For example, the phase of the first metalens (210) and the third metalens (230) is φ(r), and the phase of the second metalens (220) is φ m Let Φ(r, λ) be the phase of the second lens (200), and the following equation can be satisfied.

[0081]

[0082] Here, d=d1=d2, n g =n1=n2, k0=2π / λ0. λ0 is the center wavelength of the operating wavelength band.

[0083] As a solution to the above equation, phase delay profiles φ1, φ2, and φ3 can be obtained by each of the first metalens (210), second metalens (220), and third metalens (230) as illustrated in FIG. 7.

[0084] If the effective diameter of the second lens (200) is D and the focal length of the second lens (200) is f, and the maximum phase delay dispersion (Δ(dФ / dλ)) is assumed as follows,

[0085]

[0086] Minimum thickness value of the first spacer (250) and the second spacer (260), d min It is as follows.

[0087]

[0088] Minimum diameter, D of the blocking member (280) 0minIt is as follows.

[0089]

[0090] D 0min It can also be expressed as follows.

[0091]

[0092] Here, D is the effective aperture of the second lens (200), f is the focal length of the second lens (200), and θ max is the maximum deflection angle of the incident light by the first metalens (210).

[0093] θ max Assuming is 45 degrees, D 0min It is as follows.

[0094]

[0095] For example, D=1cm, f=5cm, n g In the case where =1.45, D 0min Silver 0.4mm, d min =1.2mm.

[0096] Figure 8 is a graph showing the relationship between the thickness of the spacer and the focal length for various maximum deflection angles by the first metalens in the second lens of Figure 6.

[0097] The graphs are for the case where d1=d2=d, and θ from 1˚ to 15˚ max Regarding the value It shows the relationship between d and focal length. Given θ max Since the maximum focal length that can be implemented is limited, a meaningful minimum value of d can be set from the graph.

[0098] FIG. 9 is a graph showing the relationship between the diameter of the blocking member and the focal length for various maximum deflection angles by the first metalens in the second lens of FIG. 6.

[0099] The graphs are for the case where d1=d2=d, and θ from 1˚ to 15˚ max Regarding the value The relationship between the diameter D0 of the blocking member and the focal length is shown. Given θ max Since the maximum focal length that can be implemented is limited, a meaningful minimum value of D0 can be set from the graph.

[0100] FIG. 10 shows the schematic structure of a second lens of another example provided in a transparent display device according to an embodiment.

[0101] In this embodiment, the second lens (201) differs from the second lens (200) of FIG. 6 only in the position of the blocking member (280), and the rest is substantially the same. As illustrated, the blocking member (280) can be positioned at the center of the second metalens (220).

[0102] Minimum thickness of the first spacer (250) and the second spacer (260), d min , minimum diameter of the blocking member (280), D 0min It can satisfy the aforementioned equation.

[0103] As described above, the metalens forming the first lens (600)(601) and the second lens (200)(201) that can be provided in the projection-type display device (1000), namely, the first metalens (610)(611), the second metalens (620)(621), and the third metalens (630)(631) of the first lens (600)(601), and the first metalens (210), the second metalens (220), and the third metalens (230) of the second lens (200), each have a structure that implements a predetermined phase profile, and we will examine an exemplary structure thereof.

[0104] FIG. 11 is a plan view showing the schematic structure of a meta-lens provided in a transparent display device according to an embodiment.

[0105] The meta-lens (ML) includes a plurality of nanostructures (NS) to exhibit a predetermined phase delay profile for incident light. The nanostructures (NS) may be disposed on a support layer (SP). The support layer (SP) may be any one of the spacer layers illustrated in FIGS. 3, 5, 6, and 10. The nanostructures (NS) may have shape dimensions smaller than the center wavelength (λ0) of the operating wavelength band. The nanostructures (NS) may have a minimum wavelength (λ0) of the operating wavelength band. m It may have shape dimensions of a subwavelength smaller than ). The operating wavelength band may be the visible light band. The nanostructure (NS) has a refractive index different from that of the support layer (SP) and other surrounding materials. The metalens (ML) can implement various phase profiles for incident light depending on the arrangement of the nanostructure (NS), and can be applied as the first metalens (610)(611), second metalens (620)(621), and third metalens (630)(631) of the first lens (600)(601) as described above, and the first metalens (210), second metalens (220), and third metalens (230) of the second lens (200).

[0106] A meta-lens (ML) comprises a plurality of phase modulation regions (R) including a plurality of nanostructures (NS) whose shape, size, and arrangement are determined according to established rules. k ...includes ). In FIG. 11, for convenience, only a few nanostructures (NS) are shown exemplarily, but multiple phase modulation regions (R k Multiple nanostructures (NS) are arranged in each )

[0107] Multiple phase modulation regions may be arranged along a predetermined direction defining the phase profile, and this direction may be a radial direction (r) away from the center (C) of the meta-lens (ML), as illustrated. However, it is not limited thereto.

[0108] The rules set in each region of the meta-lens (ML) are applied to parameters such as the shape, size (width, height), spacing, and arrangement form of the nanostructure (NS), and can be set according to the phase profile that the meta-lens (ML) intends to implement overall, for example, the phase profile exemplified in FIG. 4 or FIG. 7.

[0109] When light is incident on a meta-lens (ML) along the Z direction and passes through the meta-lens (ML), the light encounters a refractive index distribution according to an array of multiple nanostructures (NS) that have a refractive index different from that of the surrounding material. The position of the wavefront connecting points with the same phase in the path of light differs before and after encountering the refractive index distribution according to the array of nanostructures (NS), which is expressed as a phase delay. The degree of phase delay depends on the position (x, y coordinates) on a plane perpendicular to the direction of light propagation (Z direction) at the position immediately after the light passes through the nanostructures (NS) of the meta-lens (ML), and forms the transmission phase profile of the meta-lens (ML). If the transmission phase profile is polar symmetric with respect to the Z-axis passing through the center (C) of the meta-lens (ML) or has rotational symmetry of a certain angle, the phase profile can be expressed as a function of the distance r from the center (C). Based on this desired phase profile, the detailed shape, size, and arrangement of the nanostructures (NS) at each location can be determined.

[0110] A plurality of phase modulation regions are each regions representing a phase modulation pattern of a predetermined range. The plurality of phase modulation regions are a first region (R1), a second region (R2), ..., the Nth region (R1), arranged sequentially along the radial direction (r) from the center (C) of the meta-lens (ML). N ...including etc. As illustrated, the first region (R1) is circular, and the second region (R2) to the Nth region (R N ) may be an annular region. The first region (R1) to the Nth region (RN ) is a region representing a phase delay of a predetermined range, for example, a phase delay of 2π radians. Although such region divisions are not indicated on the horizontal axis of the phase profile graphs shown in FIGS. 4 and 7, the region where the phase range of the vertical axis corresponding to the center of the horizontal axis is 2π radians can be considered to correspond to the same phase modulation region.

[0111] Total number of phase modulation regions (N), width of each region (W1,..W k ,.. W N ), and the phase profile within each region can be a key variable in the performance of the meta-lens (ML).

[0112] For the meta-lens (ML) to function as a lens having refractive power, each region (R k The width of ) can be set non-uniform, for example, to decrease or increase as it moves from the center (C) to the periphery. Two adjacent regions (R k )(R k+1 ) is a region representing the same phase modulation range, and since the width in the radial direction (r) is different, the slopes of the phase change along the radial direction are different, and the slopes can vary even within each region. Accordingly, when incident light passes through each position of the meta-lens (ML), it can deflect at different angles between regions and within regions. In this way, after passing through the meta-lens (ML), the incident light is subjected to a refractive force that causes it to converge or diverge.

[0113] Area (R k The distribution of the number and width of ) is related to the magnitude (absolute value) of the effective aperture and refractive power of the meta-lens (ML), and each region (R k The sign of the refractive power can be determined depending on the rules within ). For example, the greater the refractive power, the narrower the region (R k ) can be used more, and each area (R kIn the ) positive refractive power can be realized by an arrangement of rules in which the size of the nanostructure (NS) decreases along the radial direction (an arrangement in which the phase decreases), and negative refractive power can be realized by an arrangement of rules in which the size of the nanostructure (NS) increases along the radial direction (an arrangement in which the phase increases).

[0114] FIGS. 12 and FIGS. 13 show exemplary cross-sectional views of the meta-lens of FIG. 11.

[0115] The metalens (ML) comprises a support layer (SP) and a plurality of nanostructures (NS) disposed on the support layer (SP). Between the plurality of nanostructures (NS), an surrounding material layer (EN) made of a material with a refractive index different from that of the nanostructures (NS) may be formed. Unlike what is illustrated, the surrounding material layer (EN) may be formed to a height greater than that of the nanostructures (NS), that is, to cover the top of the nanostructures (NS). The nanostructures (NS) may be arranged in a single layer as in FIG. 12, or in two layers as in FIG. 13, or in multiple layers of three or more.

[0116] The support layer (SP) has a transparent property to light in the operating wavelength band of the meta-lens (ML) and can be made of any one of the materials among glass (fused silica, BK7, etc.), quartz, polymer (PMMA, SU-8, etc.) and other transparent plastics.

[0117] The nanostructure (NS) is composed of a material having a difference in refractive index from surrounding materials, such as an surrounding material layer (EN) and a support layer (SP). For example, it may have a high refractive index with a difference of 0.2 or more from the refractive index of surrounding materials, or a low refractive index with a difference of 0.2 or more from the refractive index of surrounding materials. The difference in refractive index may be 0.2 or more, or 0.5 or more.

[0118] When the nanostructure (NS) is made of a material with a higher refractive index than the surrounding material, the nanostructure (NS) may include at least one of c-Si, p-Si, a-Si III-V compound semiconductors (GaAs, GaP, GaN, GaAs, etc.), SiC, TiO2, and SiN, and the surrounding material with a lower refractive index may include polymer materials such as SU-8, PMMA, SiO2, or SOG.

[0119] When the nanostructure (NS) is made of a material with a lower refractive index than the surrounding material, the nanostructure (NS) may include SiO2 or air, and the surrounding material with a high refractive index may include at least one of c-Si, p-Si, a-Si III-V compound semiconductors (GaAs, GaP, GaN, GaAs, etc.), SiC, TiO2, and SiN.

[0120] The nanostructure (NS) is the operating wavelength of the transparent display device (1000), that is, the minimum wavelength of the image light formed by the image projector (100). m It can have shape dimensions smaller than ). For example, the spacing between adjacent nanostructures (NS) is the minimum operating wavelength ( m It can be between 1 / 2 and 2 / 3 of ). The height of the nanostructure (NS) is 0.5λ m ~7 m It can be within the range of.

[0121] Nanostructures (NS) can have a cylindrical shape, and can also have various shapes such as polygonal columns and elliptical columns.

[0122] FIGS. 11 to 13 describe common details of meta-lenses that may be included in the first lens (600) (601) and second lens (200) (201) provided in the transparent display device (1000) according to the embodiment, and the shape and arrangement of nanostructures provided in each may be set to suit the refractive power to be implemented by each meta-lens.

[0123] FIG. 14 shows the schematic structure of a transparent display device according to another embodiment.

[0124] A transparent display device (1001) comprises an image projector (100) that outputs image light (L1), a waveguide (400) that transmits image light (L1) to the user's field of vision, a first lens (600) having negative refractive power disposed adjacent to a first surface (400a) which is the light-emitting surface of the waveguide (400), and a second lens (300) having positive refractive power disposed adjacent to a second surface (400b) facing the first surface (400a).

[0125] The transparent display device (1001) of the present embodiment differs from the transparent display device (1000) of FIG. 1 in that the second lens (300) is a refractive lens having one side as a convex curved surface, and the rest is substantially the same.

[0126] FIG. 15 shows the schematic structure of a transparent display device according to another embodiment.

[0127] A transparent display device (1002) comprises an image projector (100) that outputs image light (L1), a waveguide (400) that transmits image light (L1) to the user's field of vision, a first lens (600) having negative refractive power disposed adjacent to a first surface (400a) which is the light-emitting surface of the waveguide (400), and a second lens (200) having positive refractive power disposed adjacent to a second surface (400b) facing the first surface (400a).

[0128] The transparent display device (1002) also differs from the transparent display device (1000) of FIG. 1 in that it further includes a vision correction lens (700) positioned adjacent to the first lens (600), and the rest of the configuration is substantially the same.

[0129] The vision correction lens (700) may have a configuration that allows it to be attached to and detached from the first lens (600), for example, so as to be attached to and detached from the transparent display device (1002). The vision correction lens (700) may also be a meta lens (ML) as described above.

[0130] The vision correction lens (700) may have a refractive power suitable for the user's vision and may be assembled to the first lens (600) by the user's choice. In other words, the transparent display device (1002) of the present embodiment may include the transparent display device (1000) of FIG. 1 and a plurality of types of vision correction lenses (700) that can be assembled thereto, and one of the plurality of types of vision correction lenses (700) may be selected and assembled to the first lens (600) according to the user.

[0131] The aforementioned transparent display devices can be applied to various types of electronic devices. The aforementioned transparent display devices can be applied, for example, to augmented reality devices, to multi-video display devices, or to vehicle head-up display devices.

[0132] FIG. 16 is a conceptual diagram showing the schematic structure of an augmented reality device according to an embodiment.

[0133] The augmented reality device (2000) includes a transparent display device (1000) that provides image light (L1) and a processor (1510) that controls the transparent display device (1000) to output additional images suitable for the environment the user is looking at. The augmented reality device (2000) may also include a memory (1520) in which codes of programs to be executed on the processor (1510), other data, etc., are stored, and may also include a sensor (1530) that recognizes the user environment.

[0134] The augmented reality device (2000) is a display device that further enhances the effect of reality by combining and displaying virtual objects or information over a real-world environment. For example, additional information about the environment provided by the real world can be formed by an image projector (100) at the observer's location and provided to the observer. Such an augmented reality (AR) display can be applied to a ubiquitous environment or an Internet of Things (IoT) environment.

[0135] The image of the real world is not limited to a real environment and, for example, may be an image formed by another image device. In this case, the augmented reality device (2000) may be called a multi-image display device that displays two images together.

[0136] The augmented reality device (2000) has been exemplified as an optical system configuration provided to a single eye, but is not limited thereto and may be implemented as an optical system separately provided to both eyes.

[0137] The augmented reality device combines video light (L1) and ambient light (L2) and transmits them to the observer's field of vision. At this time, the transparent display device (1000) can be controlled by a processor (1510) so that the video light (L1) includes additional information that corresponds to the user environment. For example, the user environment is recognized by a sensor (1530), and considering the recognition result, an image of additional information suitable thereto can be formed at the image projector (100) of the transparent display device (1000).

[0138] The transparent display device (1000) provided in the augmented reality device (2000) is illustrated as the transparent display device of FIG. 1, but is not limited thereto, and a transparent display device (1001)(1002) of another embodiment or a display device modified therefrom may be employed.

[0139] The above-described transparent display devices can be configured in a wearable form. All or part of the components of the transparent display devices can be configured in a wearable form.

[0140] FIGS. 17 to 18 show the external appearance of various electronic devices employing a transparent display device according to an embodiment.

[0141] FIG. 17 shows the external appearance of an electronic device, for example, an augmented reality device, employing a transparent display device according to an embodiment. As shown in FIG. 17, the transparent display device can be applied as an eye-wearable device, such as a glasses-type display. However, it is not limited thereto and can be applied as a head-mounted display (HMD), a goggle-type display, etc., and can have a form such as a contact lens that is worn directly on the eye.

[0142] A glasses-type augmented reality device (2000) like Fig. 17 may be operated in conjunction with an electronic device such as a smartphone and may provide virtual reality (VR), augmented reality (AR), or mixed reality (MR).

[0143] The transparent display device according to the embodiment may be applied as a head-up display (HUD) (2100) of a car, as shown in FIG. 18.

[0144] FIG. 19 is a block diagram of an electronic device according to an embodiment.

[0145] Referring to FIG. 19, in a network environment (2200), an electronic device (2201) may communicate with another electronic device (2202) through a first network (2298) (short-range wireless communication network, etc.) or with another electronic device (2204) and / or a server (2208) through a second network (2299) (long-range wireless communication network, etc.). The electronic device (2201) may communicate with the electronic device (2204) through the server (2208). The electronic device (2201) may include a processor (2220), memory (2230), input device (2250), sound output device (2255), display device (2260), audio module (2270), sensor module (2210), interface (2277), haptic module (2279), camera module (2280), power management module (2288), battery (2289), communication module (2290), subscriber identification module (2296), and / or antenna module (2297). Some of these components may be omitted from the electronic device (2201), or other components may be added. Some of these components may be implemented as a single integrated circuit. For example, a fingerprint sensor of the sensor module (2210), or an iris sensor, an ambient light sensor, etc., may be implemented by being embedded in the display device (2260) (display, etc.).

[0146] The processor (2220) can execute software (program (2240), etc.) to control one or more other components (hardware, software components, etc.) of the electronic device (2201) connected to the processor (2220) and can perform various data processing or operations. As part of the data processing or operations, the processor (2220) can load commands and / or data received from other components (sensor module (2210), communication module (2290), etc.) into volatile memory (2232), process the commands and / or data stored in volatile memory (2232), and store the resulting data in non-volatile memory (2234). The processor (2220) may include a main processor (2221) (central processing unit, application processor, etc.) and an auxiliary processor (2223) (graphics processing unit, image signal processor, sensor hub processor, communication processor, etc.) that can operate independently or together with it. The auxiliary processor (2223) uses less power than the main processor (2221) and can perform specialized functions.

[0147] The auxiliary processor (2223) can control the functions and / or states associated with some of the components of the electronic device (2201), such as the display device (2260), sensor module (2210), communication module (2290), etc., on behalf of the main processor (2221) while the main processor (2221) is in an inactive state (sleep state), or together with the main processor (2221) while the main processor (2221) is in an active state (application execution state). The auxiliary processor (2223) (image signal processor, communication processor, etc.) may also be implemented as part of other functionally related components (camera module (2280), communication module (2290), etc.).

[0148] The memory (2230) can store various data required by components of the electronic device (2201), such as a processor (2220), a sensor module (2210), etc. The data may include, for example, input data and / or output data for software (program (2240), etc.) and related commands. The memory (2230) may include volatile memory (2232) and / or non-volatile memory (2234).

[0149] The program (2240) may be stored as software in memory (2230) and may include an operating system (2242), middleware (2244) and / or an application (2246).

[0150] The input device (2250) can receive commands and / or data to be used for a component (processor (2220), etc.) of the electronic device (2201) from outside the electronic device (2201) (user, etc.). The input device (2250) may include a microphone, a mouse, a keyboard, and / or a digital pen (stylus pen, etc.).

[0151] The sound output device (2255) can output a sound signal to the outside of the electronic device (2201). The sound output device (2255) may include a speaker and / or a receiver. The speaker may be used for general purposes, such as multimedia playback or recording playback, and the receiver may be used to receive incoming calls. The receiver may be combined as part of the speaker or implemented as a separate, independent device.

[0152] The display device (2260) can visually provide information to the outside of the electronic device (2201). The display device (2260) may include a display, a holographic device, or a projector and a control circuit for controlling said device. The display device (2260) may include a touch circuitry configured to detect a touch and / or a sensor circuit (such as a pressure sensor) configured to measure the intensity of the force generated by the touch. The display device (2260) may be provided in multiple units. One of the multiple display devices (2260) may include any one of the above-described transparent display devices (1000)(1001)(1002) or a transparent display device having a structure modified from them. The transparent display device provided as part of the display device (2260) may have a configuration physically separated from the main body of the electronic device (2201) and may have a form such as, for example, a glasses-type device.

[0153] The audio module (2270) can convert sound into an electrical signal or, conversely, convert an electrical signal into sound. The audio module (2270) can acquire sound through an input device (2250) or output sound through a sound output device (2255) and / or a speaker and / or headphones of another electronic device (electronic device (2102), etc.) that is directly or wirelessly connected to the electronic device (2201).

[0154] The sensor module (2210) can detect the operating state (power, temperature, etc.) of the electronic device (2201) or the external environmental state (user state, etc.) and generate an electrical signal and / or data value corresponding to the detected state. The sensor module (2210) may include a fingerprint sensor, an accelerometer, a position sensor, a 3D sensor, etc., and may also include an iris sensor, a gyroscope sensor, a barometric pressure sensor, a magnetic sensor, a grip sensor, a proximity sensor, a color sensor, an IR (infrared) sensor, a biosensor, a temperature sensor, a humidity sensor, and / or an illuminance sensor.

[0155] The interface (2277) may support one or more specified protocols that can be used for the electronic device (2201) to be connected directly or wirelessly to another electronic device (electronic device (2102), etc.). The interface (2277) may include an HDMI (High Definition Multimedia Interface), a USB (Universal Serial Bus) interface, an SD card interface, and / or an audio interface.

[0156] The connection terminal (2278) may include a connector that allows the electronic device (2201) to be physically connected to another electronic device (electronic device (2102), etc.). The connection terminal (2278) may include an HDMI connector, a USB connector, an SD card connector, and / or an audio connector (headphone connector, etc.).

[0157] The haptic module (2279) can convert electrical signals into mechanical stimulation (vibration, movement, etc.) or electrical stimulation that can be perceived by the user through tactile or kinesthetic senses. The haptic module (2279) may include a motor, a piezoelectric element, and / or an electric stimulation device.

[0158] The camera module (2280) can capture still images and video. The camera module (2280) may include a lens assembly including one or more lenses, image sensors, image signal processors, and / or flashes.

[0159] The application (2246) may include one or more applications that are executed in conjunction with the display device (2260). Such applications may enable additional information suitable for the user environment to be displayed on the display device (2260). For example, the camera module (2280) may be utilized as a sensor that recognizes the user environment, and necessary additional information may be displayed on the display device (2260) according to the recognized result.

[0160] The power management module (2288) can manage the power supplied to the electronic device (2201). The power management module (2288) can be implemented as part of a Power Management Integrated Circuit (PMIC).

[0161] The battery (2289) can supply power to the components of the electronic device (2201). The battery (2289) may include a non-rechargeable primary battery, a rechargeable secondary battery and / or a fuel cell.

[0162] The communication module (2290) can support the establishment of a direct (wired) communication channel and / or a wireless communication channel between an electronic device (2201) and another electronic device (electronic device (2202), electronic device (2204), server (2208), etc.), and the performance of communication through the established communication channel. The communication module (2290) may include one or more communication processors that operate independently of the processor (2220) (application processor, etc.) and support direct communication and / or wireless communication. The communication module (2290) may include a wireless communication module (2292) (cellular communication module, short-range wireless communication module, GNSS (Global Navigation Satellite System, etc.) communication module) and / or a wired communication module (2294) (LAN (Local Area Network) communication module, power line communication module, etc.). Among these communication modules, the corresponding communication module can communicate with other electronic devices through a first network (2298) (a short-range communication network such as Bluetooth, WiFi Direct, or IrDA (Infrared Data Association)) or a second network (2299) (a long-range communication network such as a cellular network, the Internet, or a computer network (LAN, WAN, etc.). These various types of communication modules may be integrated into a single component (single chip, etc.) or implemented as multiple separate components (multiple chips). The wireless communication module (2292) can identify and authenticate an electronic device (2201) within a communication network such as the first network (2298) and / or the second network (2299) using subscriber information (such as an International Mobile Subscriber Identifier (IMSI)) stored in the subscriber identification module (2296).

[0163] The antenna module (2297) can transmit signals and / or power to or from the outside (other electronic devices, etc.). The antenna may include a radiator made of a conductive pattern formed on a substrate (PCB, etc.). The antenna module (2297) may include one or multiple antennas. If multiple antennas are included, the communication module (2290) may select an antenna suitable for a communication method used in a communication network, such as a first network (2298) and / or a second network (2299), from among the multiple antennas. Through the selected antenna, signals and / or power may be transmitted or received between the communication module (2290) and other electronic devices. In addition to the antenna, other components (RFIC, etc.) may be included as part of the antenna module (2297).

[0164] Some of the components can be connected to each other and exchange signals (commands, data, etc.) through communication methods between peripheral devices (bus, GPIO (General Purpose Input and Output), SPI (Serial Peripheral Interface), MIPI (Mobile Industry Processor Interface), etc.).

[0165] Commands or data may be transmitted or received between the electronic device (2201) and an external electronic device (2204) through a server (2208) connected to a second network (2299). The other electronic devices (2202, 2204) may be of the same or different type as the electronic device (2201). All or part of the operations performed on the electronic device (2201) may be performed on one or more of the other electronic devices (2202, 2204) or the server (2208). For example, when the electronic device (2201) needs to perform a function or service, instead of performing the function or service itself, it may request one or more other electronic devices to perform part or all of that function or service. One or more other electronic devices that receive the request may perform additional functions or services related to the request and transmit the results of the execution to the electronic device (2201). To this end, cloud computing, distributed computing, and / or client-server computing technologies may be used.

[0166] Although the above-described transparent display device and the electronic device including it have been described with reference to the embodiments illustrated in the drawings, this is merely illustrative, and those skilled in the art will understand that various modifications and equivalent alternative embodiments are possible therefrom. Therefore, the disclosed embodiments should be considered in an illustrative rather than a restrictive sense. The scope of the rights is defined in the claims, not in the foregoing description, and all variations within the scope of equivalence should be interpreted as being included within the scope of the rights. Explanation of the symbols

[0167] 1000, 1001, 1002: Transparent display device 100: Video Projector 200, 201: Second lens 400: Waveguide 600, 601: First lens 610, 620, 630, 611, 621, 631, 210, 220, 230, ML: Metalens NS: Nanostructures EN: Surrounding material layer

Claims

Claim 1 A projection display device comprising: a projection projector that outputs image light; a waveguide that transmits the image light output from the projection projector to a user's field of vision, the waveguide having a first surface on which the image light is output and a second surface facing the first surface; a first lens disposed on the first surface, having a negative refractive power and including one or more meta-lenses; and a second lens disposed on the second surface, having a positive refractive power. Claim 2 A see-through display device according to claim 1, wherein the first lens comprises: a first meta lens disposed on the first surface and having a negative refractive power; a second meta lens disposed at a first distance from the first meta lens and having a positive refractive power; and a third meta lens disposed at a second distance from the second meta lens and having a negative refractive power. Claim 3 A see-through display device according to claim 2, further comprising: a first spacer having a thickness corresponding to the first distance disposed between the first meta lens and the second meta lens; and a second spacer having a thickness corresponding to the second distance disposed between the second meta lens and the third meta lens. Claim 4 In paragraph 3, the first spacer and the second spacer have the same refractive index and the same thickness, in a transparent display device. Claim 5 A projection-type display device according to claim 1, wherein the first lens comprises: a first meta lens disposed on the first surface and having a positive refractive power; a second meta lens disposed at a first distance from the first meta lens and having a negative refractive power; and a third meta lens disposed at a second distance from the second meta lens and having a positive refractive power. Claim 6 A projection-type display device according to claim 1, wherein the second lens is a refractive lens having one convex surface. Claim 7 A see-through display device according to claim 1, wherein the second lens comprises one or more meta lenses. Claim 8 A projection-type display device according to claim 7, wherein the second lens comprises: a first meta lens having a positive refractive power; a second meta lens having a negative refractive power and disposed at a first distance from the first meta lens; and a third meta lens having a positive refractive power and disposed at a second distance from the second meta lens. Claim 9 A see-through display device according to claim 8, further comprising: a first spacer having a thickness corresponding to the first distance disposed between the first meta lens and the second meta lens; and a second spacer having a thickness corresponding to the second distance disposed between the second meta lens and the third meta lens. Claim 10 In claim 9, the first spacer and the second spacer have the same refractive index and the same thickness, in a transparent display device. Claim 11 In Clause 10, the above first distance and the above second distance are d min Lee Sang-in, transparent display device.d min ... is as follows, where f is the focal length of the second lens, D is the effective diameter of the second lens, and n g is the refractive index, θ of the first spacer and the second spacer. max is the maximum deflection angle of the incident light by the first meta-lens. Claim 12 A see-through display device according to claim 10, wherein the second lens further comprises a blocking member that blocks light incident on the second lens from passing through the center of the second meta lens. Claim 13 In paragraph 12, the blocking member is a transparent display device positioned at the center of the first meta-lens. Claim 14 In paragraph 12, the blocking member is a transparent display device positioned at the center of the second meta-lens. Claim 15 In Clause 14, the above blocking member has a diameter of Do min Lee Sang-in, transparent display device.Do min is as follows, where f is the focal length of the second lens, D is the effective diameter of the second lens, and n g is the refractive index of the first spacer and the second spacer, θ max is the maximum deflection angle of the incident light by the first meta-lens. Claim 16 A projection-type display device according to claim 1, wherein the absolute value of the negative refractive power exhibited by the first lens is different from the absolute value of the positive refractive power exhibited by the second lens. Claim 17 A see-through display device according to claim 1, further comprising a removable vision correction lens disposed adjacent to the first lens. Claim 18 In Clause 17, the above-mentioned vision correction lens is a metal lens, and the transparent display device. Claim 19 An electronic device comprising: a transparent display device according to any one of claims 1 to 18; and a processor that controls the transparent display device to output an additional image suitable for the environment the user is looking at. Claim 20 In paragraph 19, the above-mentioned transparent display device is an electronic device that is an eye-wearable device.

Images