Display device comprising guide with reflective coatings

Abstract

To provide a display device including guides for propagating rays from one or more image sources to an observer by using a combination of refractive index interfaces and reflective coatings.SOLUTION: A display device may include a guide, a back side coating, a front side coating, an input coupler, an output coupler, and an image source. The guide may include a guide front side and a guide back side opposite the guide front side. The back side coating may line the guide back side and may reflect rays in a first waveband. The front side coating may line the guide front side and may reflect rays in a second waveband. The image source may emit rays toward the guide. The input coupler may receive the rays emitted by the image source and couple the rays into the guide. The output coupler may receive rays propagated along the guide between the guide back side and the guide front side and emit the received rays from the guide front side.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001]

[0001] Some augmented reality (AR) devices, mixed reality (MR) devices, and virtual reality (VR) devices include a visual display that utilizes a light guide or waveguide, hereinafter collectively referred to as a “guide”.

Background Art

[0002] Such visual displays generally couple light into the guide, use total internal reflection (TIR) within the guide to propagate such light along the guide to another location, and out-couple the light from the guide to the user. Since the confinement within the guide is based on TIR, the refractive index of the material used to implement the guide affects the performance characteristics of the guide. That is, a material with a higher refractive index allows for a wider range of angles at which light propagates within the guide, thereby achieving a wider field of view (FOV) or a wider generated image. Further, applications beyond AR, MR, and VR devices may benefit from confinement of light within the guide at a certain wavelength or wavelength range while allowing light of other wavelengths or wavelength ranges to pass through the guide.

[0003]

[0002] However, high refractive index materials (e.g., materials having a refractive index greater than 2) are generally more costly than materials having a lower refractive index. Thus, high refractive index materials are generally prohibitively costly for AR devices, MR devices, and / or VR devices for the general consumer. Further, the guide has an inherently limited range of angles at which light can be confined by the TIR effect.

Summary of the Invention

[0004]

[0003] By using a combination of a refractive index interface and a reflective coating, a display device comprising a waveguide that propagates light rays from one or more image sources to an observer is illustrated and / or described in relation to at least one of the figures and is more fully shown in the claims. The reflective coating supplements the refractive index interface and can increase the angle at which light rays propagate through the waveguide. In this way, the display device can achieve a wider field of view (FOV) or a wider generated image than what is possible with waveguides formed of other low refractive index materials.

[0005]

[0004] These and other advantages, aspects, and novel features of the present disclosure, as well as details of the illustrated embodiments of the present disclosure, will be more fully understood from the following description and the drawings.

[0005] Various features and advantages of the present disclosure can be more readily understood by referring to the following detailed description taken in conjunction with the accompanying drawings, in which like reference numerals indicate like structural elements.

Brief Description of the Drawings

[0006]

Figure 1

[0006] A block diagram of a computing device comprising a display device.

Figure 2A

[0007] FIG. 1 shows an embodiment of a display device suitable for the display device of FIG. 1, and is a diagram showing that the display device has a waveguide with a reflective coating.

Figure 2B

[0008] FIG. 2A is a graph of the transmission characteristics of the reflective coating of the display device of FIG. 2A.

Figure 3A

[0009] FIG. 1 shows an embodiment of a display device suitable for the display device of FIG. 1, and is a diagram showing that the display device has a waveguide with a reflective coating.

Figure 3B

[0010] FIG. 3A is a graph of the transmission characteristics of the reflective coating of the display device of FIG. 3A.

Figure 4A

[0011] FIG. 1 shows an embodiment of a display device suitable for the display device of FIG. 1, and is a view showing that the display device has a plurality of guides each provided with a reflective coating.

Figure 4B

[0012] FIG. 6 is a graph of the transmission characteristics of the reflective coating of each guide of the display device of FIG. 4A.

Figure 4C

Figure 4D

Figure 5

[0013] FIG. 1 shows an embodiment of a head-mounted display device suitable for the display device of FIG. 1.

Figure 6A

[0014] FIG. 6A is a view showing Snell's law.

Figure 6B

Figure 7

[0015] FIG. 27 is a view showing how much the reflective coating can increase the angular range in which the guides of the display devices of FIGS. 2A, 3A, 4A, and 5 can internally reflect light rays. DETAILED DESCRIPTION OF THE INVENTION

[0007]

[0016] The following discussion provides various examples of display devices and various examples of computing devices including such display devices. Such examples are non-limiting, and the appended claims should not be limited to the specific examples disclosed. In the following discussion, the terms "example" and "for example" are non-limiting.

[0008]

[0017] The figures illustrate a general manner of construction, and descriptions as well as details of well-known features and techniques may be omitted in order to avoid unnecessarily obscuring the present disclosure. Further, the elements of the figures are not necessarily to scale. For example, some dimensions of the elements of the figures may be exaggerated relative to other elements to assist in improving the understanding of the examples discussed in the present disclosure. The same reference numerals in different figures represent the same elements.

[0009]

[0018] The term “and / or” means any one or more of the items in a list conjoined by “and / or”. As an example, “x and / or y” means any element of the three-element set {(x), (y), (x, y)}. As another example, “x, y, and / or z” means any element of the seven-element set {(x), (y), (z), (x, y), (x, z), (y, z), (x, y, z)}.

[0010]

[0019] The terms “comprises,” “comprising,” “includes,” and / or “including” are “open-ended” terms that specify the presence of the recited features but do not preclude the presence or addition of one or more other features.

[0011]

[0020] The terms such as “first,” “second,” etc. may be used herein to describe various elements, and these elements should not be limited by these terms. These terms are only used to distinguish one element from another. Thus, for example, without departing from the teachings of the present disclosure, the first element discussed in the present disclosure may be referred to as the second element.

[0012]

[0021] Unless otherwise specified, the term "coupled" is used to describe two elements that are in direct contact with each other or two elements that are indirectly connected by one or more other elements. For example, if element A is coupled to element B, element A may be in direct contact with element B or may be indirectly connected to element B by an intervening element C. Similarly, the terms "over" or "on" are used to describe two elements that are in direct contact with each other or two elements that are indirectly connected by one or more other elements.

[0013]

[0022] Aspects of the present disclosure are directed to a display device or another device. Such a device may include a waveguide, a back coating, a front coating, an input coupler, an output coupler, and an image source. The waveguide includes a waveguide front face and a waveguide back face opposite the waveguide front face. The back coating may line or coat the waveguide back face and may reflect light rays in a first wavelength band. The front coating may line or coat the waveguide front face and may reflect light rays in a second wavelength band. The image source may emit light rays toward the waveguide. The input coupler may receive light rays emitted by the image source and couple the light rays into the waveguide. The output coupler may receive light rays propagated along the waveguide between the waveguide back face and the waveguide front face and emit the received light rays from the waveguide front face. Some embodiments of the display device or other device may utilize other techniques for coupling light into the waveguide. For example, such a device may place a light source inside the waveguide, couple light into the edge of the waveguide, and use a prism to couple light into the waveguide. Conversely, some embodiments of the display device or other device may utilize other techniques for coupling light out of and / or into a sensor. For example, such a device may place a sensor inside the waveguide, couple light out of the edge of the waveguide, or use a prism to couple light out of the waveguide.

[0014]

[0023] A further aspect of the present disclosure is directed to methods for a display device or another device. The method can include emitting light rays from an image source and coupling the light rays from the image source into a waveguide comprising a guide front having a front coating and a guide back having a back coating. The method can also include reflecting a first portion of the light rays between the guide front and the guide back based on a refractive index interface of the guide front and the guide back, and reflecting a second portion of the light rays between the front coating and the back coating based on a common reflection wavelength band of the front coating and the back coating. Further, the method can include out-coupling the first and second portions of the light rays from the guide front. Some exemplary methods for a display device or other device can utilize other techniques for coupling light into the waveguide. For example, such methods can include disposing a light source inside the waveguide, coupling light into the edge of the waveguide, or using a prism to couple light into the waveguide. Conversely, some exemplary methods for a display device or another device can utilize other techniques for coupling light out of the waveguide and / or into a sensor. For example, such methods can include disposing a sensor inside the waveguide, coupling light out of the edge of the waveguide, or using a prism to couple light out of the waveguide.

[0015]

[0024] Referring to FIG. 1, a block diagram of a computing device 100 is shown. The computing device 100 can include one or more processors 110, one or more storage devices 120, a display device 130, and various input / output (I / O) devices 150. In various embodiments, the computing device 100 can be implemented as an augmented reality (AR) device, a mixed reality (MR) device, a virtual reality (VR) device, or some other computing device form factor.

[0016]

[0025] Computing device 100 may include a bus and / or other interconnects that operably couple a processor 110, a memory device 120, a display device 130, and an I / O device 150 to each other. The processor 110 may be configured to execute instructions and, as a result of executing such instructions, manipulate data and control the operation of other components of the computing device 100. For this purpose, the processor 110 may include general-purpose processors available from various vendors, such as x86 processors, ARM processors, etc. However, the processor 110 may also be implemented using application-specific processors and / or other analog and / or digital logic circuits.

[0017]

[0026] The memory device 120 may include one or more volatile memory devices and / or one or more non-volatile memory devices. Generally, the memory device 120 may store software and / or firmware instructions that may be executed by the processor 110. The memory device 120 may store various types of data that may be accessed, modified, or operated on by the processor 110 in response to executing the instructions. For this purpose, the memory device 120 may include random access memory (RAM) devices, read-only memory (ROM) devices, solid-state drive (SSD) drives, flash memory devices, etc. In some embodiments, one or more of the devices of the memory device 120 may be integrated with one or more processors 110.

[0018]

[0027] The display device 130 may emit light rays to present images and / or other visual outputs. Specifically, the display device 130 may emit such light rays in response to the processor 110 executing instructions. As will be described in more detail below, the display device 130 may include a guide along which light rays from an image source propagate to the front surface of the display device 130.

[0019]

[0028] The other I / O device 150 may provide a device that enables a user or another device (e.g., another computing device, a networking device, etc.) to interact with the computing device 100. For example, the I / O device 150 may include buttons, a touch screen, a keyboard, a microphone, an audio speaker, etc., through which a person can interact with the computing device 100. The I / O device 150 may also include a network interface that enables the computing device 100 to communicate with other computing devices and / or networking devices. For this purpose, the networking interface may include a wired networking interface such as an Ethernet (IEEE802.3) interface, a wireless networking interface such as a WiFi (IEEE802.11) interface, a Bluetooth (IEEE802.15.1) interface, a wireless or mobile interface such as a cellular interface (GSM, CDMA, LTE, etc.), and / or any other type of networking interface that can provide a communication link between the computing device 100 and other computing devices and / or networking devices.

[0020]

[0029] The foregoing describes aspects of computing device 100. However, there can be significant variations in the actual implementation of computing device 100. For example, a headset implementation of computing device 100 may use very different components and may have a very different architecture than a smartphone implementation of computing device 100. Despite such differences, still, a computing device generally includes a processor that executes software and / or firmware instructions to implement various functions. Accordingly, the foregoing aspects of computing device 100 are presented from a non-limiting perspective and are presented overall from an exemplary perspective. A headset implementation of computing device 100 may use very different components and may have a very different architecture than a smartphone implementation of computing device 100. Despite such differences, still, a computing device generally includes a processor that executes software and / or firmware instructions to implement various functions. Accordingly, the foregoing aspects of computing device 100 are presented from a non-limiting perspective and are presented overall from an exemplary perspective.

[0021]

[0030] Some aspects of the present disclosure may be particularly useful for a computing device implemented as an AR device, an MR device, or a VR device. Some aspects of the present disclosure may also be beneficial for a display device of a smartphone, a computer monitor, a tablet, or other device that may utilize a guide or light transport layer for light projection or light reception. However, the present disclosure contemplates that aspects will find utility across a vast array of different computing devices, computing platforms, and / or other environments and is not intended to limit the scope of the present disclosure to any particular computing device, computing platform, and / or environment that may be recited in the appended claims.

[0022]

[0031] Next, referring to FIG. 2A, a display device 200 is shown. The display device 200 may be suitable for implementing the display device 130 of FIG. 1. The display device 200 may include an image source 210, a waveguide 220, an input coupler 231, an output coupler 232, a rear reflective coating 241, and a front reflective coating 242. The image source 210 may include a liquid crystal display (LCD) device, a liquid-crystal on silicon (LCoS) device, a light-emitting diode (LED) device, an organic light-emitting diode (OLED) device, a quantum dot device, an interferometric modulator device, or other image generation device.

[0023]

[0032] The waveguide 220 may include one or more dielectric layers that define a waveguide rear surface 221, a waveguide front surface 222 opposite the waveguide rear surface 221, and a waveguide sidewall 223 between the waveguide rear surface 221 and the waveguide front surface 222. The waveguide 220 may further include an input coupler 231 along the waveguide rear surface 221 and an output coupler 232 along the waveguide front surface 222.

[0024]

[0033] The waveguide 220 may include a rear reflective coating 241 along the waveguide rear surface 221 and a front reflective coating 242 along the waveguide front surface 222. The image source 210 may be disposed below or behind the waveguide rear surface 221 such that light or other electromagnetic rays 211 emitted by the image source 210 are aligned with the input coupler 231.

[0025]

[0034] The waveguide rear surface 221, the waveguide front surface 222, and the respective coatings 241, 242 may cooperate to confine the light rays 211 within the waveguide 220 and send the confined light rays 211 from the input coupler 231 to the output coupler 232. In various embodiments, the thickness of one or more dielectric layers forming the waveguide 220 may be defined such that the waveguide 220 supports propagation of a discrete set of modes or a continuum of modes.

[0026]

[0035] The input coupler 231 can be arranged along the guide rear surface 221. The input coupler 231 can be constructed to enable the light ray 211 emitted by the image source 210 to enter the guide 220 through the guide rear surface 221. In some embodiments, the input coupler 231 is arranged along other sides and / or surfaces of the guide 220 (e.g., the guide sidewall 223) and can receive the light ray 211 emitted by an image source aligned with such a side of the guide 220. Conversely, the output coupler 232 can be arranged along the guide front surface 222. The output coupler 232 can be constructed to enable the light ray 211 to exit the guide 220 through the guide front surface 222. In some embodiments the output coupler 232 is arranged along other sides and / or surfaces of the guide 220 (e.g., the guide sidewall 223) and can enable the light ray 211 to exit through such a side of the guide 220.

[0027]

[0036] The couplers 231, 232 can be prism couplers, diffraction couplers, metasurface couplers, or other types of optical couplers well-known in the art. The couplers 231, 232 can be embedded within one or more layers of the guide 220, etched within one or more layers of the guide 220, or attached onto the guide front surface 222, guide rear surface 221, or guide sidewall 223. Thus, the guide 220 can achieve out-coupling of the light ray 211 from the guide front surface 222.

[0028]

[0037] Although shown with a single input coupler 231 and a single output coupler 232, display device 200 may include multiple input couplers 231 and / or output couplers 232, and thus may provide multiple incoupling and / or outcoupling regions in waveguide 220. Further, output coupler 232 may be designed to have multiple outcoupling or uncoupling regions. The multiple outcoupling or uncoupling regions may be useful, for example, in extending the spatial extent of the outcoupling area by outcoupling light rays with respect to several bounces within waveguide 220.

[0029]

[0038] For clarity, FIG. 2A shows a single light ray 211 generated by image source 210. However, in various embodiments, image source 210 may generate several light rays 211 within a certain field of view (FOV). Further, image source 210 may generate light rays 211 of multiple wavelengths.

[0030]

[0039] Output coupler 232 may be designed to minimize interference with light rays from the surrounding environment (e.g., light rays from the external world) passing through waveguide 220. Hereinafter, such light rays are referred to as world light 280. Specifically, by selecting an appropriate grating pitch and / or reducing the refractive index contrast of output coupler 232, output coupler 232 may be arranged without interfering with world light 280 or without significantly interfering therewith. Output coupler 232 may extend to cover most of waveguide front face 222, or may be confined to discrete areas of waveguide 220 as shown.

[0031]

[0040] When the couplers 231, 232 are implemented as diffraction grating couplers having the same period, the light beam 211 emitted by the display device 200 should experience little or no distortion due to diffraction grating dispersion. However, if the period of the input coupler 231 is different from that of the output coupler 232, the light beam 211 may experience image distortion due to the inconsistent dispersion of the couplers 231, 232. Similarly, when the input coupler 231 is implemented as a prism coupler and the output coupler 232 is implemented as a grating coupler, or vice versa, the resulting signal emitted by the display device 200 may experience image distortion due to the inconsistent dispersion of the couplers 231, 232. Therefore, the display device 200 may include other elements such as optical elements embedded in the waveguide 220 that compensate for such distortion. Additionally, the software executed by the processor 110 and used to drive the image source 210 may modify the light beam 211 emitted by the image source 210 to compensate for such distortion.

[0032]

[0041] For MR devices and VR devices, the display device 200 generally provides the light beam generated by the image source 210 to the observer 290 without concern for providing light beams from other image sources. For example, the display device 200 of an MR device or VR device does not provide world light 280 to the observer 290. There is such a situation. Therefore, for the display device 200 of such a device, it is not necessary to allow the world light 280 to pass through the back surface 221 of the waveguide and proceed from the front surface 222 of the waveguide to the observer 290. Therefore, the reflective coatings 241, 242 of such devices may each have any broad reflective wavelength band (for example, the entire visible light wavelength band).

[0033]

[0042] Conversely, in an AR device, the display device 200 can provide not only the light rays emitted from the image source 210 to the observer 290, but also the world light 280 to the observer 290. In such an AR device, the reflective coatings 241, 242 extend over a part of the visible light wavelength band, and generally, the world light 280 can exit through the guide rear surface 221 and out of the guide front surface 222 and reach the observer 290. In this way, the observer 290 can simultaneously observe light rays from both the image source 210 and the surrounding environment. World light transmission may not be essential for an MR device and / or a VR device, but the reflective coatings 241, 242 of the display device 200 for some embodiments of the MR and / or VR devices can similarly extend over a part of the visible light wavelength band range as in the AR device.

[0034]

[0043] For example, the reflective coatings 241, 242 can be designed to have high reflectivity (low transmittance) over the green (G) wavelength band and have an operating angular range generated by the image source 210 and the input coupler 231. Further, the reflective coatings 241, 242 can be designed to have high transmittance over other visible light wavelength bands. Due to such reflectivity, the reflective coatings 241, 242 can generally allow the world light 280 from the surrounding environment to pass through the waveguide 220 and reach the observer 290, while allowing the light rays in the green (G) wavelength band to propagate from the image source 210 to the observer 290.

[0035]

[0044] The graph of FIG. 2B shows such reflectivity of the coatings 241, 242. The values shown for the green (G) wavelength band, the coating reflection band, and the reflection / transmission values of the graph are merely exemplary and do not limit the present disclosure unless specifically present in the appended claims. In various embodiments, the coatings 241, 242 can compensate for possible batch-to-batch variations and / or temperature variations of the green (G) wavelength band light rays emitted by the image source 210. Similarly, the reflectivity wavelength band of the coatings 241, 242 can compensate for possible temperature shifts and changes in the incident angle of the light rays with respect to the coatings 241, 242.

[0036]

[0045] In various embodiments, coatings 241, 242 are implemented similarly. Thus, coatings 241, 242 provide the same or substantially the same reflection wavelength band, and thus cooperate to propagate light ray 211 within the reflection wavelength bands of coatings 241, 242. In some embodiments, coatings 241, 242 may provide different reflection wavelength bands. In such embodiments, coatings 241, 242 may cooperate to propagate light ray 211 within a common wavelength band (e.g., a portion of two overlapping wavelength bands).

[0037]

[0046] In various embodiments, coatings 241, 242 may comprise alternating layers of dielectric materials and / or metallic materials having different refractive indices. For example, coatings 241, 242 may comprise alternating layers of a high refractive index material and a low refractive index material. In such embodiments, the high refractive index material may be selected from tantalum oxide, titanium oxide, silicon carbide, silicon nitride, aluminum nitride, etc. The low refractive index material may be selected from epoxy, aluminum oxide, silicon oxide, etc.

[0038]

[0047] The structure of the alternating layers may provide coatings 242, 242 with a reflective structure having a layer thickness of approximately a constant wavelength for reflection of light of a corresponding wavelength. For example, the region of interest may comprise a quarter wavelength stack having a layer thickness of one quarter of the wavelength to be reflected. In such embodiments, to reduce the width of the region, one of the layer types (e.g., the high refractive index material layer or the low refractive index material layer) provides a layer thickness of about 1.5 times or more of a quarter wavelength, and the layer of the stack may be shifted from a quarter wavelength such that the other layer type provides a layer thickness reduced from a quarter wavelength to less than or equal to one tenth of a quarter wavelength.

[0039]

[0048] A waveguide 220 formed from a high refractive index material (e.g., a material having a refractive index greater than 2) can propagate light rays over a wider angular range than a waveguide 220 formed from a low refractive index material. A wider angular range may be desirable to provide a display device 200 with a wider field of view (FOV), but high refractive index materials are generally more costly than low refractive index materials. Further, simply forming the waveguide 220 from several layers of low refractive index material does not provide a wider angular range for light propagating through the waveguide 220.

[0040]

[0049] A layer of material 601 is shown in FIG. 6A, and a light ray exits into the surrounding medium 603 at an angle A1 within the medium with respect to the normal. If the material 601 has a refractive index N1, the surrounding medium 603 has a refractive index N3, and a layer of material 602 with a refractive index N2 is added, the final exit angle A3 does not change. See, for example, FIG. 6B. According to Snell's law, N1*sin(A1)=N2*sin(A2)=N3*sin(A3) Thus, simply stacking additional layers of low refractive index material on the waveguide 220 may not improve the field of view of the display device 200.

[0041]

[0050] Accordingly, the display device 200 includes reflective coatings 241, 242 to supplement or increase the angular range reflected by the waveguide 220 for the refractive index interface. As shown in FIG. 7, the refractive index interface of the waveguide 220 may provide a first angular range 701 within which light rays internally reflect. The coatings 241, 242 may be designed to internally reflect light rays at a second angular range 702. As shown, the reflective coatings 241, 242 may be designed such that the second angular range 702 includes additional angles that do not exist within the first angular range 701 provided by the refractive index interface. For this purpose, the ranges 701, 702 may be separate or may partially overlap. The net result is that the refractive index interface and the coatings 241, 242 cooperate to improve the angle at which the light ray 211 internally reflects and thus provide a wider viewing field by the display device 200.

[0042]

[0051] Referring next to FIG. 3A, another embodiment of a display device is shown. The display device 201 may be suitable for implementing the display device 130 of FIG. 1. As shown, the display device 201 may include an image source 210, a waveguide 220, an input coupler 231, an output coupler 232, a rear reflective coating 243, and a front reflective coating 244. The image source 210 may include a liquid crystal display (LCD) device, a liquid-crystal on silicon (LCoS) device, a light-emitting diode (LED) device, an organic light-emitting diode (OLED) device, a quantum dot device, an interferometric modulator device, or other image generation device.

[0043]

[0052] The display device 201 can be implemented in the same manner as the display device 200. However, the coatings 243 and 244 of the display device 201 are different from the coatings 243 and 244 of the display device 200. Specifically, in addition to the green (G) wavelength band of the coatings 241 and 242, the coatings 243 and 244 can be designed to have high reflectance (low transmittance) across the red (R) wavelength band and the blue (B) wavelength band. Furthermore, the reflective coatings 243 and 244 can be designed to have high transmittance across other visible light wavelength bands. Due to such reflectance, the reflective coatings 243 and 244 can generally allow ambient world light 280 from the surrounding environment to pass through the waveguide 220 and reach the observer 290, and at the same time, allow light rays in the red (R), green (G), and blue (B) wavelength bands to propagate from the image source 210 to the observer 290.

[0044]

[0053] The graph of FIG. 3B shows such reflectance of the coatings 243 and 244. The values shown for the red (R), green (G), and blue (B) wavelength bands, the coating reflection bands, and the reflection / transmission values of the graph are merely exemplary and do not limit the present disclosure unless specifically recited in the appended claims. In various embodiments, the coatings 243 and 244 can compensate for possible batch-to-batch variations and / or temperature variations of light rays in the red (R), green (G), and / or blue (B) wavelength bands emitted by the image source 210. Similarly, the reflectance wavelength bands of the coatings 243 and 244 can compensate for possible temperature shifts and changes in the angle of incidence of light rays on the coatings 243 and 244.

[0045]

[0054] Next, referring to FIG. 4A, another embodiment of the display device is shown. The display device 202 may be suitable for implementing the display device 130 of FIG. 1. As shown, the display device 202 may include image sources 210r, 210g, 210b, guides 220r, 220g, 220b, input couplers 231r, 231g, 231b, output couplers 232r, 232g, 232b, rear reflection coatings 241r, 241g, 241b, and front reflection coatings 242r, 242g, 242b. The image sources 210r, 210g, 210b may be disposed under or behind the guide rear surface 221r.

[0046]

[0055] Each of the guides 220r, 220g, 220b may be implemented in the same manner as the guide 220 of the display device 200. Specifically, each of the guides 220r, 220g, 220b may have respective guide rear surfaces 221r, 221g, 221b, respective guide front surfaces 222r, 222g, 222b opposite to the respective guide rear surfaces 221r, 221g, 221b, and respective guide sidewalls 223r, 223g, 223b between the respective guide rear surfaces 221r, 221g, 221b and the respective guide front surfaces 222r, 222g, 222b. Each of the guides 220r, 220g, 220b may further include input couplers 231r, 231g, 231b along the guide rear surfaces 221r, 221g, 221b and output couplers 232r, 232g, 232b along the guide front surfaces 222r, 222g, 222b.

[0047]

[0056] Each of the guides 220r, 220g, 220b may include respective rear surface reflection coatings 241r, 241g, 241b along the guide rear surfaces 221r, 221g, 221b and front surface reflection coatings 242r, 242g, 242b along the guide front surfaces 222r, 222g, 222b. Each image source 210r, 210g, 210b may be disposed below or behind the guide rear surface 221r such that the light rays 211r, 211g, 211b emitted by the image sources 210r, 210g, 210b are aligned with the respective input couplers 231r, 231g, 231b. In this way, the light rays 211r, 211b, 211g may be incoupled into the respective guides 220r, 220b, 220g. Although shown as three separate image sources, in some embodiments, the image sources 210r, 210g, 210b may be provided by a single imaging device.

[0048]

[0057] The output couplers 232r, 232g, 232b of the guides 220r, 220g, 220b may be aligned perpendicular to each other such that the outcoupled light rays of the lower guide pass through the output coupler of the upper guide. Specifically, the guide 220b may be disposed above the guide 220g, and the output coupler 232b of the guide 220b may be disposed above the output coupler 232g of the guide 220g. Further, the guide 220g may be disposed above the guide 220r, and the output coupler 232g of the guide 220g may be disposed above the output coupler 232r of the guide 220r. In this way, the outcoupled light ray 211r of the guide 220r may pass through the guides 220g, 220b disposed above the guide 220r and the respective output couplers 232g, 232b disposed above the guide 220r. Similarly, the outcoupled light ray 211g of the guide 220g may pass through the guide 220b disposed above the guide 220g and its output coupler 232b. Accordingly, the observer 290 may receive the light rays 211r, 211g, 211b of the image sources 210r, 210g, 210b through the guide front surface 222b.

[0049]

[0058] The display device 202 may transport light rays 211r, 211b, 211g from the image sources 210r, 210g, 210b to the observer 290. Specifically, the display device 202 may couple the light rays 211r, 211g, 211b into their respective guides 220r, 220g, 220b via the input couplers 231r, 231g, 231b. The total internal reflection (TIR) inside the guides 220r, 220g, 220b and the reflectivity of their coatings are combined to confine the light rays 211r, 211g, 211b and allow them to propagate from the input couplers 231r, 231g, 231b to the output couplers 232r, 232g, 232b. The output couplers 232r, 232g, 232b may then radiate or out-couple the light rays 211r, 211g, 211b from their guide fronts 222r, 222g, 222b to the observer 290.

[0050]

[0059] As shown in FIG. 4A, the display device 202 may support three different wavelength bands (e.g., red, green, blue). However, the display device 202 may be implemented with any number of wavelength bands by using an appropriate number of guides. Further, in an exemplary embodiment, the guide 220b includes a guide front 222b that interfaces with the external environment (e.g., air). In some embodiments, an air gap is maintained between each of the guides 220r, 220g, 220b, ensuring that both the guide fronts 222r, 222g, 222b and the guide rears 221r, 221g, 221b interface with a medium (e.g., air) having the same refractive index. This ensures that the fronts and rears of each of the guides 220r, 220g, 220b achieve the same internal refraction.

[0051]

[0060] The graph of FIG. 4B shows the reflectance of coatings 241r and 242r. The graph of FIG. 4C shows the reflectance of coatings 241g and 242g. The graph of FIG. 4D shows the reflectance of coatings 241b and 242b. The values shown for each wavelength band (e.g., red (R), green (G), and blue (B)), for the coating reflection bands, and the reflectance / transmittance values of the graphs are merely exemplary and do not limit the present disclosure unless specifically recited in the appended claims. In various embodiments, the coatings may compensate for possible batch-to-batch variations and / or temperature variations in the wavelength bands of the light rays emitted by each image source 210r, 210g, 210b. Similarly, the reflectance wavelength bands of coatings 241r, 241g, 241b, 242r, 242g, 242g may compensate for possible temperature shifts and changes in the angle of incidence of the light rays with respect to coatings 241r, 241g, 241b, 242r, 242g, 242g.

[0052]

[0061] Next, referring to FIG. 5, another embodiment of a display device is shown. Display device 203 may be suitable for implementing display device 130 of FIG. 1. Display device 203 may include a first display device 203R for the first eye 290R of observer 290 and a second display device 203L for the second eye 290L of observer 290. In various embodiments, display device 203 may be glasses, a visor, a headset, or other AR / MR / VR de It can be implemented as a head-mounted device such as a spray device form factor. For this purpose, the display device 203 may include a frame 205 having arms 207R, 207L, and a bridge 209. The arms 207R, 207L are disposed proximate to the outer ends of the display devices 203R, 203L, and the bridge 209 may span between the inner ends of the display devices 203R, 203L. The frame 205 holds the first display device 203R and the second display device 203L and may be placed on the face of the observer 290. Specifically, the observer 290 places the arms 207R, 207L above the observer 290's ears and places the bridge 209 above the nasal bridge of the observer 290's nose, thereby placing the first display device 203R and the second display device 203L in front of the observer 290's eyes 290R, 290L, respectively.

[0053]

[0062] As shown, each display device 203R, 203L may be implemented in the same manner as the display device 200. That is, the first display device 203R may include an image source 210R, a waveguide 220R, an input coupler 231R, an output coupler 232R, a rear reflective coating 241R, and a front reflective coating 242R. Similarly, the second display device 203L may include an image source 210L, a waveguide 220L, an input coupler 231L, an output coupler 232L, a rear reflective coating 241L, and a front reflective coating 242L.

[0054]

[0063] In some embodiments, the display device 203 may include additional AR / MR / VR components such as, for example, an eye-tracking module, a 3D sensing module, a remote controller module, a video camera, a microphone, and / or a speaker. In AR applications, the display devices 203R, 203L may be implemented to allow world light 280 to pass through respective waveguides 220R, 220L and reach the eyes 290R, 290L of the observer 290. In VR or MR applications, the display devices 203R, 203L may be implemented to prevent world light 280 from passing through respective waveguides 220R, 220L. Accordingly, the coatings 241R, 241L, 242R, 242L may be implemented with a high reflectivity wavelength band wider than the green (G) wavelength band of the display device 200. In some embodiments, the high reflectivity wavelength band of the coatings 241R, 241L, 242R, 242L may extend across the entire visible light wavelength band.

[0055]

[0064] Those skilled in the art will understand that this disclosure includes references to some examples, but that various changes can be made and equivalents can be substituted without departing from the scope of this disclosure. Further, modifications can be made to the disclosed examples without departing from the scope of this disclosure. For example, the display devices 200, 201, 202, 203 possess various described features. Additional display device embodiments can mix, match, and / or combine the features of the display devices 200, 201, 202, 203. Accordingly, the appended claims are not limited to the disclosed examples and are intended to encompass all embodiments within their respective scopes.

Description of the Reference Numerals

[0056] 100 Computing Device 110 Processor 120 Memory Device 130 Display Device 150 Input / Output (I / O) Device 200 Display Device 201 Display device 202 Display device 203 Display device 205 Frame 207 Arm 209 Bridge 210 Image source 220 Guide 221 Rear side of guide 222 Front side of guide 223 Side wall of guide 231 Input coupler 232 Output coupler 241 Rear reflection coating 242 Front reflection coating 243 Rear reflection coating 244 Front reflection coating 280 World light 290 Observer 601 Material 603 Surrounding medium

Claims

1. a first image source configured to emit a first image source beam; a first guide including a first guide front surface and a first guide rear surface opposite the first guide front surface; A display device comprising: a first back-guide surface coating along the first back-guide surface that reflects light in a first wavelength band of the first image source light; a first front guide surface coating along the first front guide surface that reflects light in a second wavelength band of the first image source light; the first wavelength band spans a first portion of the visible light wavelength band; the second wavelength band spans a second portion of the visible wavelength band; the first guide front surface coating and the first guide rear surface coating confine and propagate within the first guide a portion of the first image source light beam within both the first wavelength band and the second wavelength band, and present the portion of the first image source light beam to an observer through the first guide front surface. Display device.

2. 10. The display device of claim 1, a first guide input coupler configured to couple the first image source light beam into the first guide; a first guide output coupler configured to emit from the first guide front surface the portions of the first image source light beam within both the first waveband and the second waveband; A display device comprising:

3. 10. The display device of claim 1, the first guide provides a refractive index interface that internally reflects light rays within a first angular range of the first image source light rays; the first guide back surface coating and the first guide front surface coating cooperate to provide internal reflection for rays within a second angular range of the first image source rays. Display device.

4. 4. The display device of claim 3, wherein the first angle range and the second angle range overlap.

5. 4. The display device of claim 3, wherein the first and second angular ranges do not overlap.

6. 4. The display device of claim 3, wherein the second angular range is at least partially outside the first angular range.

7. 10. The display device of claim 1, wherein the first guide front coating and the first guide back coating each comprise one or more dielectric layers.

8. 10. The display device of claim 1, wherein the first guide front coating and the first guide back coating each comprise one or more metal layers.

9. 10. The display device of claim 1, wherein the first waveband and the second waveband overlap.

10. 10. The display device of claim 1, wherein the first wavelength band and the second wavelength band are substantially the same.

11. 10. The display device of claim 1, the first guide back surface coating is configured to reflect light rays within any of a first plurality of non-overlapping wavelength bands of the first image source light rays, the first wavelength band being included; the first guiding front surface coating is configured to reflect light rays of the first image source light within any of a second plurality of non-overlapping wavelength bands including the second wavelength band, and each wavelength band of the first plurality of non-overlapping wavelength bands is substantially the same as a corresponding wavelength band of the second plurality of non-overlapping wavelength bands. Display device.

12. 10. The display device of claim 1, a second image source configured to emit a second image source beam; a second guide including a second guide front surface and a second guide rear surface opposite the second guide front surface; Equipped with a second back guide surface coating along the second back guide surface that reflects light in a third wavelength band of the second image source light; a second front guide surface coating along the second front guide surface that reflects light in a fourth wavelength band of the second image source light; the third wavelength band spans a third portion of the visible light wavelength band; the fourth wavelength band spans a fourth portion of the visible light wavelength band; the second guide front surface coating and the second guide rear surface coating confine and propagate within the second guide a portion of the second image source light beam within both the third wavelength band and the fourth wavelength band, and present the portion of the second image source light beam to the observer through the second guide front surface. Display device.

13. 13. The display device of claim 12, comprising a frame, the frame comprising: a first arm adjacent to the first guide outer end of the first guide; a second arm adjacent to the second guide outer end of the second guide; a bridge between a first guide inner end of the first guide and a second guide inner end of the second guide; a display device.

14. 13. The display device of claim 12, wherein the second rear guide surface is disposed above the first front guide surface.

15. 15. The display device of claim 14, comprising an air gap between the second guide rear surface and the first guide front surface.

16. 13. A display device according to claim 12, a third image source configured to emit a third image source beam; a third guide including a third guide front surface and a third guide rear surface opposite to the third guide front surface; Equipped with a third guide back surface coating along the third guide back surface that reflects light in a fifth wavelength band of the third image source light; a third front guide surface coating along the third front guide surface that reflects light in a sixth wavelength band of the third image source light; the fifth wavelength band spans a fifth portion of the visible light wavelength band; the sixth wavelength band spans a sixth portion of the visible light wavelength band; the third guide front surface coating and the third guide rear surface coating confine and propagate within the third guide a portion of the third image source light beam within both the fifth wavelength band and the sixth wavelength band, and present the portion of the third image source light beam to the observer through the third guide front surface. Display device.

17. 17. A display device according to claim 16, the first wavelength band and the second wavelength band correspond to a red wavelength band; the third wavelength band and the fourth wavelength band correspond to a green wavelength band; the fifth wavelength band and the sixth wavelength band correspond to a blue wavelength band; Display device.

18. 17. The display device of claim 16, comprising an imaging device, the imaging device including the first image source, the second image source, and the third image source.

Images