Waveguide-type display device

Abstract

A waveguide-type display device is provided. The waveguide-type display device includes a waveguide through which an image travels, and a leaked image reducer configured to reduce emission of a leaked image, which is among the image and which leaks from the waveguide without total internal reflection in the waveguide, to the outside through a volume grating.

Description

[0001] Cross-references to related applications

[0002] This application claims priority to Korean Patent Application No. 10-2020-0175833, filed on December 15, 2020, with the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference in its entirety. Technical Field

[0003] Exemplary embodiments of this disclosure relate to waveguide-type display devices, and more specifically, to waveguide-type display devices capable of reducing the amount of images output to the outside. Background Technology

[0004] Virtual reality (VR) is a technology that allows humans to experience a sense of real life in a computer-generated virtual world. Augmented reality (AR) is a technology that allows virtual images to blend with the physical environment or space of the real world. Virtual reality displays, or near-eye displays that implement augmented reality, reproduce virtual images in space using a combination of optical and stereoscopic images. In such near-eye displays, display resolution and processing are crucial.

[0005] Near-eye displays utilize very thin waveguides and diffractive optical elements that direct image information from arbitrary light sources, allowing for compact design. In addition to their extreme thinness, these diffractive optical elements exhibit photoselectivity, responding only to light incident at specific angles and wavelengths. Diffractive optical elements can be designed to transmit light from a real object as is, and these properties allow them to respond only to light already transmitted into the waveguide, enabling augmented reality displays.

[0006] Furthermore, in display devices using waveguides and diffractive optical elements, light diffracted to higher-order terms by the diffractive optical elements can be emitted externally through the waveguide surface, causing noise emission. In other words, light diffracted to higher-order terms by the diffractive optical elements can be emitted in a direction different from the user's eye. This noise is a design obstacle and may potentially infringe on privacy because an external observer can view the user's image. Summary of the Invention

[0007] An exemplary embodiment provides a waveguide-type display device that reduces leakage images, i.e. noise, from the outside of the waveguide.

[0008] Additional aspects will be set forth in part in the description which follows and will be apparent in part from the description or may be learned by practice of exemplary embodiments.

[0009] According to one aspect of this disclosure, a waveguide-type display device is provided, comprising: a first waveguide; a first coupler provided on the first waveguide and configured to input light corresponding to an image into the first waveguide; a second coupler provided on the first waveguide and configured to output light propagating through the first waveguide to the outside of the first waveguide; and an optical element including a volumetric grating configured to reduce leakage light that leaves the first waveguide without total internal reflection.

[0010] Optical elements can also be configured to transmit light incident from the real environment.

[0011] Optical elements may be provided on a first region of a first waveguide, which is different from a second region on which a first coupler is provided and a third region on which a second coupler is provided.

[0012] The leaked light can have a diffraction order greater than or equal to 2, and the leaked light is generated by light diffracted by at least one of the first coupler and the second coupler and propagated through the first waveguide.

[0013] The optical element may include a deflection element configured to deflect light by at least a portion of the volume grating at a deflection angle greater than the angle of incidence of the leaking light, based on the leaking light incident on the volume grating.

[0014] The optical element may also include a second waveguide provided parallel to the first waveguide, wherein light deflected from the deflection element may be totally internally reflected and propagated in the second waveguide.

[0015] The deflection element can be provided between the first waveguide and the second waveguide.

[0016] The deflection element may have a first refractive index that is less than the second refractive index of the first waveguide and less than the third refractive index of the second waveguide.

[0017] The first waveguide, the second waveguide, and the deflection element can be arranged sequentially.

[0018] The deflection element may include a first deflection element and a second deflection element, wherein a second waveguide may be provided between the first deflection element and the second deflection element.

[0019] The optical element may also include a light absorber provided on the second waveguide.

[0020] Light absorbers can have an absorption rate of approximately 80% or more.

[0021] The optical absorber can be provided at at least one end of the second waveguide.

[0022] Light deflected by the deflection element can enter the first waveguide and propagate in the first waveguide through total internal reflection.

[0023] Optical elements may also include a light absorber provided on the first waveguide.

[0024] The deflection element may include a holographic optical element in which a volume grating is formed by interference between a reference light and a signal light, and wherein the deflection element may be configured to output a signal light that responds to the leakage light among a plurality of signal lights recorded in the deflection element.

[0025] The deflection element may include a metamaterial in which a volumetric grating is formed as an array of nanostructures with a size smaller than the wavelength of the leaked light, and the metamaterial alters the direction of the leaked light.

[0026] The optical element may include: a first optical element configured to reduce the leakage of light having a first optical characteristic to the outside of the leaked light; and a second optical element configured to reduce the leakage of light having a second optical characteristic to the outside of the leaked light, wherein the optical element is further configured to reduce the leakage of light having a third optical characteristic to the outside of the leaked light.

[0027] The first optical characteristic, the second optical characteristic, and the third optical characteristic correspond to different wavelengths.

[0028] The light with the first optical property is red light, the light with the second optical property is green light, and the light with the third optical property is blue light.

[0029] The waveguide-type display device may also include a third coupler provided on the optical element, wherein the third coupler is configured to allow the leaked light to be re-intruded onto the first waveguide.

[0030] The waveguide-type display device may also include an imaging device configured to provide an image to the first coupler.

[0031] Waveguide-type display devices can be near-eye display devices.

[0032] According to another aspect of this disclosure, a display device is provided, comprising: a communication circuit configured to receive a command signal from an external device; a display configured to output an image based on the command signal; a first waveguide configured to receive and propagate input light corresponding to the image; and an optical element configured to reduce leakage light in the light propagating through the first waveguide that leaves the first waveguide without total internal reflection.

[0033] According to another aspect of this disclosure, a display system is provided, comprising a first device and a second device. The first device includes: a display configured to output an image; a first waveguide configured to receive and propagate input light corresponding to the image; and an optical element configured to reduce leakage light in the light propagating through the first waveguide that leaves the first waveguide without total internal reflection. The second device includes a processor configured to output commands to control the display to output an image. Attached Figure Description

[0034] The above and other aspects, features, and advantages of certain exemplary embodiments of this disclosure will become more apparent from the following description, taken in conjunction with the accompanying drawings, in which:

[0035] Figure 1 This is a schematic diagram of a waveguide-type display device according to an exemplary embodiment;

[0036] Figure 2 This is an illustration showing a k-plot of a holographic optical element according to an exemplary embodiment;

[0037] Figure 3A This is a reference diagram illustrating a method for recording reference light and signal light in a holographic optical element according to an exemplary embodiment;

[0038] Figure 3B This is a reference diagram illustrating the output of signal light from a holographic optical element based on an incident leaked image, according to an exemplary embodiment.

[0039] Figure 4 This is an illustration of a display device according to an exemplary embodiment;

[0040] Figure 5 This is an illustration of a display device including a plurality of deflection elements according to an exemplary embodiment;

[0041] Figure 6 This is an illustration of a display device according to an exemplary embodiment, in which an optical coupler and a leaky image reducer share a waveguide;

[0042] Figure 7 This is an illustration of a display device including a plurality of leaky image reducers according to an exemplary embodiment;

[0043] Figure 8 This is an illustration of a display device for reusing leaked images according to an exemplary embodiment;

[0044] Figure 9A , 9B Each of 9C is a plan view illustrating a portion of a metamaterial according to an exemplary embodiment;

[0045] Figure 10This is an illustration showing a type of near-eye display device according to an exemplary embodiment; and

[0046] Figure 11 This is a block diagram illustrating a display device according to an exemplary embodiment. Detailed Implementation

[0047] Reference will now be made in detail to embodiments illustrated in the accompanying drawings, where similar reference numerals refer to similar elements throughout the drawings. Exemplary embodiments may take different forms and should not be construed as limited to the description set forth herein. Therefore, the exemplary embodiments described below with reference to the accompanying drawings are merely illustrative of aspects. As used herein, the term "and / or" includes any one of the associated enumerations and all combinations thereof. Expressions such as "at least one of..." modify the entire column of elements when following a column of elements, rather than individual elements within the column.

[0048] The inventive concept will now be described more fully with reference to the accompanying drawings, in which exemplary embodiments of the inventive concept are illustrated. The embodiments of the inventive concept are provided merely to embody the inventive concept and should not be construed as limiting the scope of the invention or restricting the scope of the invention. Exemplary embodiments that can be readily deduced by one of ordinary skill in the art from the detailed description of the inventive concept and the embodiments are to be construed as being included in the inventive concept.

[0049] It should also be understood that the terms "comprising" or "including" should not be construed as necessarily including all the constituent elements and operations described in the specification, nor should they be construed as excluding some of the constituent elements or operations or excluding additional constituent elements and operations. Furthermore, in the specification, the terms "unit" or "...module" refer to a unit or module that processes at least one function or operation, and can be implemented by hardware, software, or a combination of hardware and software.

[0050] It should be understood that, although the terms "first," "second," etc., may be used herein to describe various constituent elements, these constituent elements should not be limited by these terms. These terms are used only to distinguish one constituent element from another.

[0051] When using the expressions "above" or "on top of" to describe the orientation of a component, the orientation of the component can include not only "closely above / below / left / right in contact" but also "on / below / left / right in a non-contact manner." Examples of these embodiments will now be described in detail with reference to the accompanying drawings.

[0052] Figure 1 This is a schematic diagram of a waveguide-type display device 100 according to an exemplary embodiment. The waveguide-type display device 100 may be a near-eye display device.

[0053] Reference Figure 1 The waveguide-type display device 100 may include an imaging device 110 that provides an image and an optical coupler 120 that combines the image provided by the imaging device 110 with light generated in the real environment. The image may be light provided by the imaging device 110.

[0054] Imaging device 110 may include a light source for providing an image. Imaging device 110 may output an image based on an electrical signal. Imaging device 110 may include, for example, a liquid crystal display (LCD), a liquid crystal on silicon (LCoS), an organic light-emitting diode (OLED) display, a light-emitting diode (LED) display, etc.

[0055] Optical coupler 120 may include a first waveguide 122 that transmits images via total internal reflection and transmits light with respect to the external environment, an input coupler 124 that inputs or transmits images from imaging device 110 to the first waveguide 122, and an output coupler 126 that outputs images transmitted through the first waveguide 122 to the outside of the first waveguide 122.

[0056] The first waveguide 122 can propagate images via total internal reflection. The first waveguide 122 may include a transparent component, such as glass or a transparent plastic material.

[0057] An image incident on the input coupler 124 is diffracted by the input coupler 124 and enters the first waveguide 122, where it is transmitted along the length direction (e.g., the y-direction) of the first waveguide 122. The image can be incident on the input coupler 124 vertically or obliquely. The input coupler 124 can be a diffractive optical element or a holographic optical element that diffracts the incident image.

[0058] When the image traveling through the first waveguide 122 enters the output coupler 126, the image is output to the user's eye outside the first waveguide 122. Similar to the input coupler 124, the output coupler 126 can be a diffractive optical element or a deflector element 132 that diffracts the incident image.

[0059] Simultaneously, some images diffracted by the input coupler 124 and incident on the first waveguide 122 may not undergo total internal reflection within the first waveguide 122 and may be output to the outside through the surface of the first waveguide 122. For example, light incident on the output coupler 126 may be diffracted and enter the user's eye. However, some light may be diffracted, propagated in a direction different from the user's eye, and output to the outside through the surface of the first waveguide 122. For example, some light may be diffracted, propagated in a direction opposite to the user's eye, and output to the outside through the surface of the first waveguide 122 on the side opposite to the user's eye. The light propagated in the direction opposite to the user's eye may be a higher-order term, such as second-order or higher-order diffracted light.

[0060] The light emitted from the first waveguide 122 in the direction opposite to the user's eye is referred to as a leaked image because it contains image information. The leaked image can be observed by an observer other than the user. Because the leaked image includes various polarization states, wavelengths, and directional components, it is difficult to prevent the leaked image from being emitted externally.

[0061] The waveguide-type display device 100 according to an exemplary embodiment may further include a leakage image reducer 130, which reduces leakage image output to the outside by transmission through the surface of the first waveguide 122. The leakage image reducer 130 can prevent leakage image output to the outside and can also transmit light incident from the outside, i.e., the real environment. The leakage image reducer 130 can be provided on the area of ​​the first waveguide 122 where the input coupler 124 and the output coupler 126 are not arranged.

[0062] The leaked image reducer 130 may include a deflection element 132 configured to output light at an output angle greater than the incident angle of the leaked image, a second waveguide 134 that propagates the light output from the deflection element 132 via total internal reflection, and a light absorber 136 configured to absorb the light transmitted from the second waveguide 134.

[0063] The deflection element 132 can be arranged between the first waveguide 122 and the second waveguide 134. The deflection element 132 can have a refractive index that is lower than that of the first waveguide and the second waveguide 134. Therefore, the first waveguide 122 and the second waveguide 134 can be configured to propagate light with total internal reflection.

[0064] When a leaked image or light from the first waveguide 122 is incident on the deflection element 132, the deflection element 132 can output light into the second waveguide 134 at an output angle greater than the incident angle of the leaked image. The deflection element 132 may include holographic optical elements, metamaterials, polarizers, etc. The light output from the deflection element 132 may be the leaked image itself, or it may be a signal light that responds to the leaked image among the signal light recorded in the deflection element 132. The deflection element 132 outputs light at an output angle greater than the incident angle, and hereinafter, the light output from the deflection element 132 may be referred to as deflected light.

[0065] The second waveguide 134 can be arranged parallel to the first waveguide 122. The surface of the first waveguide 122 can be divided into a first surface facing the user's eye and a second surface facing a direction different from the user's eye, and the second waveguide 134 can be arranged on the outer surface of the first waveguide 122. For example, the surface of the first waveguide can have an inner surface facing the user's eye and an outer surface facing outward, and the second waveguide 134 can be arranged on the outer surface of the first waveguide 122. According to an exemplary embodiment, similar to the first waveguide 122, the second waveguide 134 may include a transparent component, such as glass or a transparent plastic material. Light output from the deflection element 132 can be totally internally reflected in the second waveguide 134 and can be transmitted to one end of the second waveguide 134.

[0066] The light absorber 136 may be disposed at at least one end of the second waveguide 134. Light transmitted through the second waveguide 134 is absorbed and disappears by the light absorber 136, thus preventing leakage of image output to the outside. According to an exemplary embodiment, the absorption rate of the light absorber 136 may be 80% or more. The light absorber 136 may include a black matrix material, a resin polymer, etc., but this disclosure is not limited thereto. Therefore, according to another exemplary embodiment, the absorption rate of the light absorber 136 may be different and the material of the light absorber 136 may be different.

[0067] The deflection element 132 may include a holographic optical element in which a reference light and a signal light are recorded in a volumetric grating. Of the signal light recorded on the holographic optical element, the signal light that responds to the leaked image can be output. The signal light can be output from the holographic optical element at an output angle greater than the incident angle of the leaked image, such that the signal light can undergo total internal reflection in the second waveguide 134.

[0068] The wavelength selectivity and angle selectivity of a holographic optical element can be controlled based on the thickness and refractive index of the materials included in the holographic optical element. The holographic optical element may include non-volatile materials. For example, it may include at least one of an optopolymer and an inorganic crystal. The holographic optical element may have a thickness ranging from about 1 mm to about 10 mm. For example, in an optopolymer with a thickness of about 3 mm, about 500 signal beams can be recorded as reference beams with a bandwidth of about 0.1 nm, while in an optopolymer with a thickness of about 5 mm, about 500 signal beams can be recorded as reference beams with a bandwidth of about 0.05 nm.

[0069] Figure 2 This is an illustration of a k-plot of a holographic optical element according to an exemplary embodiment. Reference light and signal light can be recorded on the holographic optical element to satisfy, for example... Figure 2 The grating conditions shown are illustrated. Figure 2 In the middle, K ref K represents the direction of propagation of the reference light. sig This indicates the direction of signal light transmission. When the reference light and signal light are recorded together in a holographic optical element, the direction of transmission is indicated by K in the holographic optical element. gra A volumetric grating can be formed in the direction.

[0070] When a leaked image is incident on a holographic optical element on which a volumetric grating is formed, a signal light that responds to the leaked image can be output from the signal light previously recorded on the holographic optical element. Here, the signal light that responds to the leaked image refers to the signal light recorded together with the same reference light as the leaked image.

[0071] On the other hand, the direction of light propagation when the critical angle that satisfies the total internal reflection condition in the second waveguide 134 is called K -reflected In this case, the preferred orientation is K of the volumetric grating. gra and the direction K of light transmitted at the critical angle -reflected They can be parallel to each other, so that light that is to be completely reflected will not reach the holographic optical element.

[0072] In the holographic optical element according to an exemplary embodiment, a volumetric grating can be formed in advance using a reference light and a signal light. While the reference light can vary depending on the optical characteristics of the leaked image and the angle of incidence, the signal light corresponding to each reference light can have an output angle that causes the signal light to be completely reflected in the second waveguide 134. Furthermore, the optical characteristics of the signal light can vary depending on the optical characteristics of the reference light, or can have an optical characteristic independent of the optical characteristics of the reference light.

[0073] Figure 3A This is a reference diagram illustrating a method for recording reference light and signal light in a holographic optical element according to an exemplary embodiment. (Refer to...) Figure 3A By using a reference light with the same optical properties and incident angle as the leaked image, the signal light can be recorded in a holographic optical element (HOE). Signal light L s It can be in the first reference light L r1 With the first incident angle θ r1 The holographic optical element HOE is illuminated under illumination. Signal light L... s incident angle θ s It can be greater than the first reference light L r1 First incident angle θ r1 Then, the first reference beam L r1 and signal light L s It is recorded in the form of a volumetric grating, therefore, the signal light L s It can be recorded in a holographic optical element (HOE). The reference light can include at least one of red, blue, and green light.

[0074] The signal light can be recorded in the holographic optical element (HOE) while the incident angle of the reference light is changed. Even if the incident angle of the reference light changes, the signal light L... s incident angle θ s It can also remain constant. Figure 3A The text describes recording signal light together with N reference lights according to various incident angles, but the embodiments are not limited to this.

[0075] Figure 3B This is a reference diagram illustrating the output signal light from the holographic optical element (HOE) based on the incident image of a leaked image according to an exemplary embodiment.

[0076] like Figure 3B As shown, the leaked image L i It can be at the first incident angle θ r1 It is incident on the holographic optical element HOE. At the first incident angle θ r1 Incident leakage image L i It can have the same angle as the first incident angle θ r1 The first incident reference beam L r1 Same optical properties. Incident leakage image L i The signal light and the first reference light L r1 The signal light L recorded together s It reacts, and the holographic optical element HOE can output signal light L. s Output signal light L s Output angle θ s It can be used with signal light L s The incident angle θ at the time of recording s Same; and the output signal light L sThe output direction can be the same as when the signal light L s The incident directions are the same when they are recorded.

[0077] Leakage image L i It can be at the second incident angle θ r2 It is incident on the holographic optical element HOE at a second incident angle θ. r2 Incident leakage image L i It can have the same characteristics as at the second incident angle θ r2 The incident second reference beam L r2 Same optical properties. Incident leakage image L i The signal light and the second reference light L r2 The signal light L recorded together s It reacts, and the holographic optical element HOE can output signal light L. s .

[0078] Regardless of the leaked image L i The incident direction of the signal light L output from the holographic optical element HOE is such that... s Output angle θ s They can be the same. Signal light L s Output angle θ s It can be a signal light L s The angle of total internal reflection in the second waveguide 134 is possible. Therefore, regardless of the incident angle of the leaked image, the signal light L... s All images are fully internally reflected in the second waveguide 134, thereby reducing the leakage of image output to the outside.

[0079] The signal light only responds to and is output from light that has the same optical properties as the reference light recorded along with it, but does not respond to light with different optical properties. Therefore, light incident from the outside will not respond to the holographic optical element (HOE) and can pass through it.

[0080] Figure 3A and 3B A transmissive holographic optical element is shown as deflection element 132, but it is not limited thereto. A reflective holographic optical element may also be used as deflection element 132.

[0081] Figure 4 This is an illustration of a display device 100a according to an exemplary embodiment. Figure 4The image leakage reducer 130a of the display device 100a may also include a second waveguide 134, a deflection element 132, and a light absorber 136. The second waveguide 134 may be arranged between the first waveguide 122 and the deflection element 132. The second waveguide 134 may have a refractive index less than or equal to that of the first waveguide 122, and the deflection element 132 may be reflective.

[0082] Of the images transmitted in the first waveguide 122, leaked images that do not undergo total internal reflection in the first waveguide 122 but leak through the surface of the first waveguide 122 can leave the first waveguide 122 and enter the second waveguide 134. The leaked images can be refracted as they are incident on the second waveguide 134.

[0083] A portion of the leaked image can be totally internally reflected in the second waveguide 134 and can be transmitted to one end of the second waveguide 134. Furthermore, by having the leaked image absorbed by the light absorber 136 arranged at one end of the second waveguide 134, the leaked image can be prevented from being output to the outside.

[0084] Furthermore, some other portions of the leaked image may not undergo total internal reflection in the second waveguide 134 and may pass through the surface of the second waveguide 134 and exit the second waveguide 134. A deflection element 132 disposed on the outer surface of the second waveguide 134 can respond to the incident leaked image that does not undergo total internal reflection in the second waveguide 134 to output deflected light that can undergo total internal reflection in the second waveguide 134. The deflected light can be transmitted along the length of the second waveguide 134 while undergoing total internal reflection. Furthermore, by having the leaked image absorbed by a light absorber 136 disposed at one end of the second waveguide 134, the leakage image can be prevented from being output to the outside.

[0085] According to an exemplary embodiment, Figure 4 The second waveguide 134 is arranged in contact with the first waveguide 122, and the second waveguide 134 may have a refractive index lower than that of the first waveguide 122. The deflection element 132 can be manufactured to output only deflected light with respect to light in the leaked image that is not totally internally reflected in the second waveguide 134. Therefore, the amount of volumetric grating in the deflection element 132 can be reduced.

[0086] The deflection element 132 may include both a transmission type deflection element and a reflection type deflection element.

[0087] Figure 5 This is an illustration of a display device 100b including a plurality of deflection elements according to an exemplary embodiment. Figure 5As shown, the plurality of deflection elements may include a first deflection element 132a and a second deflection element 132b, with a second waveguide 134 located therebetween separating the first deflection element 132a and the second deflection element 132b from each other. Therefore, a leaked image leaking from the first waveguide 122 can be deflected by the first deflection element 132a and enter the second waveguide 134. When the first deflection element 132a is a holographic optical element, the light deflected by the first deflection element 132a can be the signal light that responds to the leaked image among the signal lights recorded in the holographic optical element. The deflected light can be transmitted in the second waveguide 134 by total internal reflection and absorbed by the light absorber 136.

[0088] Furthermore, light that does not undergo total internal reflection in the second waveguide 134 and passes through the surface of the second waveguide 134 can be deflected again by the second deflecting element 132b and re-enter the second waveguide 134. The light deflected again by the second deflecting element 132b can undergo total internal reflection in the second waveguide 134 and proceed in parallel to be absorbed by the light absorber 136. The first deflecting element 132a and the second deflecting element 132b can function as a dual filter for leaked images.

[0089] The leak image reducer may not include a separate second waveguide 134 and may use the first waveguide 122.

[0090] Figure 6 This is an illustration of a display device 100c according to an exemplary embodiment, in which an optical coupler and a leakage image reducer 130c share a waveguide. (Comparison) Figure 1 and Figure 6 The deflection element 132 can be arranged on the outer surface of the first waveguide 122. The deflection element 132 can be arranged in the region of the first waveguide 122 where the input coupler 124 and the output coupler 126 are not arranged. The optical absorber 136 can be arranged at one end of the first waveguide 122.

[0091] The deflection element 132 can deflect the leaked image transmitted through the first waveguide 122 without total internal reflection. The deflected light can then be re-incident on the first waveguide 122, undergo total internal reflection in the first waveguide 122, travel along the length of the first waveguide 122, and can then be absorbed by the light absorber 136.

[0092] The leakage image reducer 130c can be configured as multiple leakage image reducers. For example, the leakage image reducer 130c may include multiple deflection elements that respond to each wavelength.

[0093] Figure 7 This is an illustration of a display device 100d comprising a plurality of image leakage reducers 130d according to an embodiment. Figure 7As shown, the leaked image reducer 130d may include a first leaked image reducer 130-1 that reduces the emission of light with a first optical characteristic from a leaked image, a second leaked image reducer 130-2 that reduces the emission of light with a second optical characteristic from a leaked image, and a third leaked image reducer 130-3 that reduces the emission of light with a third optical characteristic from a leaked image. The light with the first optical characteristic may be red light, the light with the second optical characteristic may be green light, and the light with the third optical characteristic may be blue light. However, this disclosure is not limited thereto.

[0094] Each of the first to third leak image reducers 130-1, 130-2 and 130-3 may include a deflection element 132 that outputs deflected light by responding to light having specific optical properties of a leak image, a second waveguide 134 for causing the light output from the deflection element 132 to travel in one direction by total internal reflection, and a light absorber 136 for absorbing the light transmitted through the second waveguide 134.

[0095] Each of the first to third leak image reducers 130-1, 130-2 and 130-3 only prevents leaked images with specific optical properties from being output to the outside. Therefore, the efficiency of the deflection element 132 included in each of the first to third leak image reducers 130-1, 130-2 and 130-3 can be improved.

[0096] according to Figure 7 The exemplary embodiments shown herein employ a plurality of leakage image reducers 130-1, 130-2, and 130-3 in response to each wavelength, but the embodiments are not limited thereto. For example, according to another exemplary embodiment, the plurality of leakage image reducers 130-1, 130-2, and 130-3 may respond to each incident angle of the leakage image.

[0097] according to Figure 1 , Figure 4 , Figure 5 , Figure 6 and Figure 7 The exemplary embodiment shown corresponds to the deflection of light from the leaked image being absorbed by the light absorber 136, but the embodiment is not limited thereto. For example, according to another exemplary embodiment, the leaked image can be re-intruded onto the first waveguide 122 to become an image intruded onto the user's eye.

[0098] Figure 8 This is an illustration of a display device 100e that reuses leaked images according to an exemplary embodiment. Figure 8As shown, optical coupler 120a may include a first input coupler 124a for inputting an image provided from imaging device 110 to first waveguide 122, and a second input coupler 124b for inputting light output from leakage image reducer 130d to first waveguide 122. Furthermore, a first output coupler 126 that outputs an image propagating through first waveguide 122 in the direction of the user's eye may be arranged on first waveguide 122, and a second output coupler 138 that outputs traveling light from second waveguide 134 to optical coupler 120a may be arranged on leakage image reducer 130d.

[0099] The first input coupler 124a can input an image output from the imaging device 110 into the first waveguide 122, and the image can be incident on the user's eye through the first output coupler 126 while undergoing total internal reflection in the first waveguide 122.

[0100] Simultaneously, the leaked image, i.e., the image transmitted through the first waveguide 122 without total internal reflection, is incident on the deflection element 132, and the deflection element 132 can output deflected light corresponding to the leaked image to the second waveguide 134. After total internal reflection in the second waveguide 134, the deflected light can re-enter the first waveguide 122 via the second output coupler 138 and the second input coupler 124b, thus entering the user's eye like an image.

[0101] To reuse the leaked image, the deflection element 132 can have a volumetric grating to output deflected light with the same image information as the leaked image. That is, the output deflected light that responds to the leaked image has the same image information, only transmitted in a different direction than the leaked image; therefore, the deflected light can be referred to as a diffracted leaked image. As described above, since the leaked image is reused, a decrease in image brightness due to the leaked image can be prevented while propagating through the first waveguide 122.

[0102] Although the deflection element 132 has been described using holographic optics, the embodiments are not limited thereto. For example, the deflection element 132 may comprise a metamaterial formed by arranging an array of nanostructures comprising multiple nanostructures to form a volumetric grating. This array of nanostructures may have a subwavelength dimension. Here, subwavelength refers to a dimension smaller than the wavelength of the light to be used (i.e., the leaked image).

[0103] Any dimension of the shape constituting the nanostructure, such as thickness, width, length, or at least one of the gaps between nanostructures, can have a subwavelength dimension. Metamaterials can alter the direction of light passing through them by controlling the phase change of light generated at the nanostructure interfaces. Optical properties, such as the operating wavelength of the metamaterial, can be controlled based on the size and arrangement of the multiple nanostructures constituting the metamaterial.

[0104] Metamaterials can include dielectrics. In the case of metal-based metamaterials, there is significant optical loss in the wavelength range of approximately 400 nm to approximately 700 nm (the visible light band). Dielectric metamaterials, however, function well even in the visible light band without significant loss. The dielectrics constituting the nanostructures of metamaterials can include, but are not limited to, dielectric materials such as silicon oxide (SiOx), silicon nitride (SiNx), titanium oxide (TiOx), aluminum oxide (AlOx), hafnium oxide (HfOx), etc., and can be modified in various ways.

[0105] Figures 9A to 9C Each of these is a plan view illustrating a portion of a metamaterial according to an exemplary embodiment.

[0106] Reference Figure 9A Metamaterials can include dielectric metamaterials and multiple nanostructures NS10. The multiple nanostructures NS10 can be arranged in a two-dimensional manner. The orientation of the nanostructures NS10 can gradually change from a first region to a second region of the metamaterial. The transmission path of light through the metamaterial can be altered by controlling the phase changes of light generated in the multiple nanostructures NS10.

[0107] The shape and arrangement of the multiple nanostructures NS10 constituting the metamaterial can be modified in various ways. These deformations... Figure 9B and Figure 9C As shown in [the image]. Figure 9B Multiple NS20 nanostructures were arranged within it, and in Figure 9C Multiple NS30 nanostructures are arranged within the metamaterial. The properties of the metamaterial can vary depending on the shape, size, and arrangement of the multiple nanostructures constituting the metamaterial. Nanostructures can have various shapes, such as rings, partially rings, H-shapes, I-shapes, and U-shapes. Furthermore, the metamaterial can comprise a single array of nanostructures or multiple stacked arrays of nanostructures. When a leakage image is incident on the metamaterial, the transmission direction can be altered through refraction, diffraction, transmission, etc., to output the leakage image.

[0108] The aforementioned waveguide-type display device can be a near-eye display device. For example, the display device can be applied to a head-mounted display (HMD). Furthermore, the display device 100 can be applied to an eyeglass-type display or a goggle-type display. Figure 10 This is an illustration of a type of near-eye display device 100 according to an exemplary embodiment.

[0109] Near-eye display devices can be used in conjunction with (or connected to) smartphones.

[0110] Figure 11 This is a block diagram illustrating a display device 100f according to an exemplary embodiment. (Refer to...) Figure 11 The display device 100f includes a first device D1 comprising an imaging device 110, an optical coupler 120, a leakage image reducer 130, and a first communication circuit 510, and a second device D2 comprising a second communication circuit 520 and a processor 300. The imaging device 110, the optical coupler 120, and the leakage image reducer 130 have already been described above, so detailed descriptions of them will be omitted.

[0111] The first device D1 can be a wearable device, such as an HMD; while the second device D2 can be an electronic device separate from the wearable device, such as a mobile phone or a computer.

[0112] The first communication circuit 510 and the second communication circuit 520 can provide control commands from the processor 300 to the imaging device 110. The first communication circuit 510 and the second communication circuit 520 may include short-range wireless communication circuits, mobile communication circuits, etc. According to an exemplary embodiment, the first communication circuit 510 and the second communication circuit 520 can provide control commands from the processor 300 to the leakage image reducer 130. For example, the processor 300 can output control commands to change the properties of the metamaterial in the deflection element 132 of the leakage image reducer 130.

[0113] The method of controlling the imaging device 110 by the processor 300 can be implemented as a software program including instructions stored in a computer-readable storage medium. According to an exemplary embodiment, the storage medium may be a memory or a storage device. As an apparatus capable of recalling stored instructions from the storage medium and operating according to the recalled instructions in accordance with the disclosed embodiments, the computer may include a display device according to the disclosed embodiments.

[0114] Although exemplary embodiments of waveguide-type displays have been described in detail with reference to the accompanying drawings illustrating exemplary embodiments of the present disclosure to aid in understanding the inventive concept, those skilled in the art will understand that various changes in form and detail may be made without departing from the spirit and scope of the inventive concept. Therefore, the scope of the inventive concept is not defined by the detailed description of the invention, but rather by the appended claims.

[0115] According to this disclosure, it is possible to reduce the output of images that leak from the outside of the waveguide.

[0116] It should be understood that the exemplary embodiments described herein should be considered descriptive only and not for limiting purposes. Descriptions of features or aspects in each embodiment should generally be considered applicable to other similar features or aspects in other embodiments. Although one or more exemplary embodiments have been described with reference to the accompanying drawings, those skilled in the art will understand that various changes in form and detail may be made without departing from the spirit and scope defined by the appended claims.

Claims

1. A waveguide-type display device, comprising: First waveguide; A first coupler is provided on the first waveguide and configured to input light corresponding to the image into the first waveguide; A second coupler is provided on the first waveguide and configured to output light propagating through the first waveguide to the outside of the first waveguide; as well as An optical element, comprising a volumetric grating configured to reduce leakage light that leaves the first waveguide without total internal reflection in light propagating through it. The optical element includes a deflection element configured to deflect the leaked light incident from the first waveguide onto the volumetric grating by at least a portion of the volumetric grating at a deflection angle greater than the incident angle of the leaked light. The light deflected by the deflection element enters the first waveguide and propagates within it via total internal reflection. The deflection element includes a holographic optical element in which the volumetric grating is formed by interference between a reference light and a signal light, or the deflection element includes a metamaterial in which the volumetric grating is formed as a nanostructure array having a size smaller than the wavelength of the leaked light, and the metamaterial alters the direction of the leaked light.

2. The waveguide-type display device according to claim 1, wherein, The optical element is also configured to transmit light incident from the real environment.

3. The waveguide-type display device according to claim 1, wherein, The optical element is provided on a first region of the first waveguide, which is different from the second region on which the first coupler is provided and the third region on which the second coupler is provided.

4. The waveguide-type display device according to claim 1, wherein, The leaked light has a diffraction order greater than or equal to 2, and the leaked light is generated by diffracting light propagating through the first waveguide by at least one of the first coupler and the second coupler.

5. The waveguide-type display device according to claim 1, wherein, The optical element further includes a second waveguide parallel to the first waveguide, and The light deflected by the deflection element is totally internally reflected and propagates in the second waveguide.

6. The waveguide-type display device according to claim 5, wherein, The deflection element is provided between the first waveguide and the second waveguide.

7. The waveguide-type display device according to claim 6, wherein, The deflection element has a first refractive index, which is less than the second refractive index of the first waveguide and less than the third refractive index of the second waveguide.

8. The waveguide-type display device according to claim 5, wherein, The first waveguide, the second waveguide, and the deflection element are arranged sequentially.

9. The waveguide-type display device according to claim 5, wherein, The deflection element includes a first deflection element and a second deflection element, and The second waveguide is provided between the first deflection element and the second deflection element.

10. The waveguide-type display device according to claim 5, wherein, The optical element also includes a light absorber provided on the second waveguide.

11. The waveguide-type display device according to claim 10, wherein, The light absorber has an absorption rate of 80% or more.

12. The waveguide-type display device according to claim 10, wherein, The optical absorber is provided at at least one end of the second waveguide.

13. The waveguide-type display device according to claim 1, wherein, The optical element further includes a light absorber provided on the first waveguide.

14. The waveguide-type display device according to claim 1, wherein, The deflection element is configured to output a signal light that responds to the leaked light among a plurality of signal lights recorded in the deflection element.

15. The waveguide-type display device according to claim 1, wherein, The optical element includes: A first optical element is configured to reduce the leakage of light having a first optical characteristic from the leaked light to the outside; and The second optical element is configured to reduce the leakage of light with second optical properties from the leaked light to the outside. The optical element is further configured to reduce the leakage of light with a third optical property to the outside.

16. The waveguide-type display device according to claim 15, wherein, The first optical characteristic, the second optical characteristic, and the third optical characteristic correspond to different wavelengths.

17. The waveguide-type display device according to claim 15, wherein, The light with the first optical property is red light. The light with the second optical property is green light, and The light with the third optical property is blue light.

18. The waveguide-type display device according to claim 1, further comprising a third coupler provided on the optical element, wherein, The third coupler is configured to allow the leaked light to be incident on the first waveguide again.

19. The waveguide-type display device of claim 12, further comprising an imaging device configured to provide an image to the first coupler.

20. The waveguide-type display device according to claim 12, wherein, The waveguide-type display device is a near-eye display device.

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