Near-eye display with reduced visual artifacts

Abstract

A near-eye display device system includes a first lens and a frame supporting the first lens in front of a first eye of a user. The system also includes a display screen having a red, green, blue (RGB) emission spectra which may include a red emission band having a full width half maximum of 70 nm + / -15nm, and a green emission band having a full width half maximum 70 nm + / -15nm. The first lens may include a dispersion correction lens and has a numerical aperture of 0.1 or less, or no-dispersion correction and a numerical aperture of 0.25 or less.

Description

NEAR-EYE DISPLAY WITH REDUCED VISUAL ARTIFACTSInventors:Pingfan Wu Ning LuCLAIM OF PRIORITY

[0001] This application claims priority to U.S. Provisional Patent Application No. 63 / 649,947, entitled “NEAR-EYE DISPLAY WITH REDUCED VISUAL ARTIFACTS”, filed May 21 , 2024, which is incorporated by reference herein in its entirety.FIELD

[0002] The following is related generally to the field of viewing devices and, more specifically, to virtual and mixed reality displays.BACKGROUND

[0003] Near eye displays are used in myriad virtual and augmented reality devices. One consequence of near eye-displays is the “screen door effect”. The screen door effect (SDE) is a visual anomaly that appears in near eye displays, including virtual reality (VR) displays, augmented reality (AR) displays and other head-mounted displays (HMDs). The SDE is characterized by a visible grid-like pattern of fine lines or gaps resembling a screen door between pixels on a screen in front of a human eye viewing the display device. The SDE arises because the resolution of current neareye displays is not high enough to match the visual acuity of the human eye. Consequently, when viewed up close, the individual pixels and the spaces between them become noticeable, creating the SDE. The SDE can be a distraction and negatively impact the perceived quality of the VR experience.

[0004] The SDE may be considered similar to a reverse of aliasing problem that affected early computer monitors and (liquid crystal display) LCD televisions, when the modulation transfer function (MTF) of the imaging optics and the eye are higher than the pixel density or spatial resolution of the display. Traditionally, attempts to solve thisproblem have involved increasing the display resolution or using algorithms or optics to blur the image.

[0005] Vergence is the simultaneous movement of both eyes in opposite directions to obtain or maintain single binocular vision. When focusing on a near object, the eyes converge (move towards each other), and when focusing on a distant object, they diverge (move away from each other). Accommodation refers to the process by which the eye's lens changes shape to focus light on the retina. This adjustment allows us to see objects clearly at different distances. When viewing a near object, the ciliary muscles contract, causing the lens to thicken and increase its optical power. Conversely, when looking at a distant object, these muscles relax, and the lens flattens to decrease its optical power. Vergence-accommodation conflict (VAC) is a visual phenomenon that occurs when the brain receives mismatching cues between vergence and accommodation of the eye. This VAC commonly occurs in virtual reality devices, augmented reality devices, and other types of stereoscopic displays. The effect can be unpleasant and cause eye strain. Vergence or independent inward / outward rotation of eyes is engaged to fixate on objects and perceive them as single. Incorrect vergencies can cause double vision. Accommodation is the eye’s focusing mechanism and it is engaged to produce a sharp image on a retina. Both mechanisms are neurally linked forming the accommodation-convergence reflex of eyes. In normal conditions, the human visual system expects vergence and accommodation distances to match. When viewing most artificial 3D images or displays, vergence and accommodation distances for the most part are mismatched. The human visual system has not evolved to view these types of artificial 3D images comfortably, so VAC can be a very unpleasant sensation for the viewer.SUMMARY

[0006] One general aspect includes a near-eye display device system. The near - eye display device system also includes a first lens. The system also includes a display screen having a red, green, blue (RGB) emission spectra may include a red (R) emission band having a full width half maximum of 70 nm + / -10nm, and a green (G) emission band having a full width half maximum 70 nm + / -10nm. The system alsoincludes a frame supporting the first lens in between a first eye of a user and the display screen.

[0007] Implementations may include the near-eye display device system wherein the display screen has a blue emission band having a full width half maximum 30 nm or less. Implementations may include the near-eye display device system of any of the foregoing implementations wherein the RGB emission specta comprises a red emission band having a full width half maximum of 80 nm + / - 5nm, and a green emission band having a full width half maximum 80 nm + / - 5nm. Implementations may include the near-eye display device system wherein the first lens comprises a multielement lens. Implementations may include the near-eye display device system wherein the first lens has a dispersion correction lens and has a numerical aperture (NA) size of 0.25 or less. Implementations may include the near-eye display device system of any of the foregoing implementations wherein the first lens has is a dispersion correction lens and has a numerical aperture (NA) of 0.1 or less. Implementations may include the near-eye display device system wherein the first lens comprises a single element lens. Implementations may include the near-eye display device system wherein the first lens has no dispersion correction and has a numerical aperture 0.25 or less. Implementations may include the near-eye display device system wherein the first lens has no dispersion correction and has a numerical aperture 0.1 or less. Implementations may include the near-eye display device system wherein the first lens is a microlens array having no dispersion correction. Implementations may include the near-eye display device system of any foregoing implementation further including a processor configured to: render images for presentation on the display screen. Implementations may include the near-eye display device system of any foregoing implementation including a second lens, a frame supporting the second lens in front of a second eye of a user; a second display screen having an RGB emission spectra may include a red emission band having a full width half maximum of 70 nm + / -10nm, and a green emission band having a full width half maximum 70 nm + / -10nm.

[0008] One general aspect includes a near-eye display device system. The near - eye display device system includes a first lens. The system also includes a framesupporting the first lens in front of a first eye of a user. The system also includes a display screen having an RGB emission spectra. The system also includes where the first lens has a dispersion correction lens and has a numerical aperture 0.1 or less.

[0009] Implementations may include the near-eye display device system wherein the first lens comprises a multi-element lens. Implementations may include the near- eye display device system where the RGB emission spectra may include a red emission band having a full width half maximum of 70 nm + / -10nm, and a green emission band having a full width half maximum 70 nm + / -10nm. Implementations may include the near-eye display device system of any of the foregoing implementations wherein the RGB emission specta comprises a red emission band having a full width half maximum of 80 nm + / - 5nm, and a green emission band having a full width half maximum 80 nm + / - 5nm. Implementations may include the near-eye display device system of any foregoing implementation wherein the display screen has a blue emission band having a full width half maximum 30 nm or less. Implementations may include the near-eye display device system of any foregoing implementation further including a processor configured to: render images for presentation on the display screen. Implementations may include the near-eye display device system of any foregoing implementation further including a second lens, a frame supporting the second lens in front of a second eye of a user and the second lens has a dispersion correction lens and. Implementations may include the near-eye display device system of any foregoing implementation wherein the display screen comprises a first display screen associated with the first eye and first lens and a second display screen associated with the second eye and second lens. Implementations may include the near-eye display device system of any foregoing implementation wherein each display screen is a microdisplay. Implementations may include the near-eye display device system of any foregoing implementation wherein each display screen is a partially transmissive and partially reflective panel.

[0010] One general aspect includes a near-eye display device. The near - eye display device also includes a first lens. The device also includes a frame supporting the first lens in front of a first eye of a user. The device also includes a display screen having an RGB emission spectra. The device also includes where the first lens has no dispersion correction and has a numerical aperture 0.25 or less.

[0011] Implementations may include the near-eye display device where the RGB emission spectra may include a red emission band having a full width half maximum of 70 nm + / -10nm, and a green emission band having a full width half maximum 70 nm + / -10nm. Implementations may include the near-eye display device of any of the foregoing implementations wherein the RGB emission specta comprises a red emission band having a full width half maximum of 80 nm + / - 5nm, and a green emission band having a full width half maximum 80 nm + / - 5nm. Implementations may include the near-eye display device wherein display screen has a blue emission band having a full width half maximum 30 nm or less. Implementations may include the near- eye display device system wherein the first lens is a single element lens. Implementations may include the near-eye display device wherein first lens is a microlens array having no dispersion correction. Implementations may include the near-eye display device further including a processor configured to: render images for presentation on the display screen. Implementations may include the near-eye display device system of any foregoing implementation further including a second lens, a frame supporting the second lens in front of a second eye of a user and the second lens has no dispersion correction and has a numerical aperture 0.25 or less.

[0012] Another general aspect includes a user equipment device. The user equipment device includes a first lens. The device also includes a frame supporting the to place the first lens at a distance in front of a first eye of a user. The device also includes a display screen having an RGB emission spectra. The device also includes a storage medium may include computer instructions. The device also includes one or more processors coupled to communicate with the storage medium, where the one or more processors execute the instructions to cause the device to create an image on the display screen. The device also includes where the emission spectra of the display screen may include a red emission band having a full width half maximum of 70 nm + / -10nm, and a green emission band having a full width half maximum 70 nm + / -10nm. Implementations may include the user equipment device wherein the display screen has a blue emission band having a full width half maximum 30 nm or less.

[0013] Another general aspect includes a user equipment device which includes a first lens. The device also includes a frame supporting the first lens in front of a first eye of a user. The device also includes a display screen having an RGB emissionspectra. The device also includes a storage medium may include computer instructions. The device also includes one or more processors coupled to communicate with the storage medium, where the one or more processors execute the instructions to cause the device to create an image on the display screen. The device also includes where the first lens includes a dispersion correction and has a numerical aperture 0.1 or less.

[0014] Implementations may include the foregoing user equipment device of where the emission spectra of the display screen may include a red emission band having a full width half maximum of 70 nm + / -10nm, and a green emission band having a full width half maximum 70 nm + / -1 Onm. Implementations may include the user equipment device of any of the foregoing implementations wherein the RGB emission specta comprises a red emission band having a full width half maximum of 80 nm + / - 5nm, and a green emission band having a full width half maximum 80 nm + / - 5nm. Implementations may include the user equipment device of where the display screen has a blue emission band having a full width half maximum 30 nm or less.

[0015] One general aspect includes a user equipment device which includes a first lens. The device also includes a frame supporting the first lens in front of a first eye of a user. The device also includes a display screen having an RGB emission spectra. The device also includes a storage medium which may include computer instructions. The device also includes one or more processors coupled to communicate with the storage medium, where the one or more processors execute the instructions to cause the device create an image on the display screen. The device also includes where the first lens includes no dispersion correction and has an aperture diameter of 5 mm or less.

[0016] Implementations may include the above user equipment device of where the emission spectra of the display screen may include a red emission band having a full width half maximum of 70 nm + / -10nm, and a green emission band having a full width half maximum 70 nm + / -1 Onm. Implementations may include the user equipment device of where the display screen has a blue emission band having a full width half maximum 30 nm or less.

[0017] This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter. The claimed subject matter is not limited to implementations that solve any or all disadvantages noted in the Background.BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Aspects of the present disclosure are illustrated by way of example and are not limited by the accompanying Figures for which like references indicate elements.

[0019] Figures 1A and 1 B are views of a user wearing a head-mounted, near-eye display device.

[0020] FIG. 2 illustrates the unity of rendering binocular display.

[0021] FIG. 3 illustrates an arrangement for an embodiment of an immerse display.

[0022] FIG. 4 is a block diagram of a testing setup in accordance with the disclosed technology.

[0023] FIG. 5A is an emission spectrum of a typical display.

[0024] FIG. 5B illustrates a graph of luminous efficiency of the eye.

[0025] FIG. 5C is an emission spectrum illustrating the bandwidth of RGB emissions in a display in accordance with the disclosed technology.

[0026] FIG. 6A is a plan view of a lens such as that used embodiments herein.

[0027] FIG. 6B is a cutaway view along line A-A in FIG. 6A.

[0028] FIGs. 6C and 6D are illustrations of multi-element pancake lenses suitable for use with the described technology.

[0029] FIG. 7 is a graph of 20% of the Modular Transfer Function (MTF) in Cycles per Degree (CPD) vs. the eye accommodation depth in diopters with a dispersion correcting lens having an aperture of 5mm.

[0030] FIG. 8 is a graph of 20% of the MTF in CPD vs. the eye accommodation depth in diopters with a dispersion correcting lens having an aperture of 2 mm.

[0031] FIG. 9 is a graph of 20% of the MTF in CPD vs. the eye accommodation depth in diopters for a non-dispersion correcting lens aperture 2 mm for a display with 43 nm FWHM bandwidth in the green and red emission spectra.

[0032] FIG. 10 is a graph of 20% of the MTF in CPD vs. the eye accommodation depth in diopters for a non-dispersion correcting lens aperture 2 mm for a display with 70 nm FWHM bandwidth in the green and red emission spectra.

[0033] FIG. 11 is a block diagram of a near eye display device.DETAILED DESCRIPTION

[0034] Techniques are described for reducing or eliminating the screen door effect and easing vergence-accommodation conflict in near eye (virtual, augmented or mixed reality) display devices. In embodiments, near eye displays are formed with multi-pixel display panels wherein each pixel comprises a display element of a given display technology but which is designed to have a wide spectral bandwidth in the green and red spectra. This may include a display having an RGB emission spectra with a red (R) emission band having a full width half maximum of 70 nm + / - 15nm (and in some embodiments 80 nm + / - 5nm), and a green (G) emission band having a full width half maximum 70 nm + / - 10nm (and in some embodiments 80 nm + / - 5nm). In some embodiments, the display screen is further configured to have a blue (B) emission band having a full width half maximum of 25 nm + / -20nm or less. In other embodiments, other types of displays may be used. In near eye displays for augmented reality devices, display elements may be positioned out of the line of vision of a user’s eye and images transmitted to a see-through, partially reflective panel in front of the eye using, for example, waveguides.

[0035] In embodiments, the disclosed technology provides an increased spectral bandwidth in the green and red spectra. The increased display spectral bandwidth so that the peak resolution of the optics can be matched by the peak resolution of the display panels in cycles per degree (CPD). CPD is a measure used to describe how well one can see details of an object without them appearing blurry. It represents the number of line pairs (alternating black and white stripes) that one can distinguish within one degree of your visual field. CPD is closely related to spatial frequency, which is expressed as the number of cycles (line pairs) per degree of visual angle. It’s commonly used in visual perception studies, especially when examining contrast sensitivity. The Modulation Transfer Function (MTF) characterizes the sharpness of a photographic imaging system or its components (such as lenses, film, image sensors, etc.). The MTF curve shows how well the system reproduces different spatial frequencies (measured in CPD) at various pupil sizes.

[0036] According to the Shannon Sampling Principle, a sampling rate is equal to twice the bandwidth (2B), which is the minimum required to capture a signal without aliasing (distortion). Thus, the display resolution in pixel per degree should be higher than two times (2x) of that display optics and eye resolution in cycles per degree. In embodiments, a focusing lens with a lower numerical aperture than conventionally used lenses is used to focus a user’s vision on the display in a near eye display device. Such a reduced numerical aperture lens can comprise a dispersion correcting lens. In embodiments, a focusing lens which does not correct dispersion may be used with a conventional numeric aperture or a reduced numerical aperture. Through decreasing the display optics numerical apertures and broadening the display emission spectra, the retina image peak resolution is reduced and eye depth of focus ranges are extended.

[0037] The making and use of embodiments of this disclosure are discussed in detail below. It should be appreciated, however, that the concepts disclosed herein can be embodied in a wide variety of specific contexts, and that the specific embodiments discussed herein are merely illustrative and do not serve to limit the scope of the claims. Further, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of this disclosure as defined by the appended claims.

[0038] Figures 1 A and 1 B are a side and top view of a near-eye display device 100 which may comprise a virtual reality or augmented reality display device worn by a user 10. FIG. 1A is a side view of the display device 100, and FIG. 1 B is a top view of the display device 100. The near-eye display device 100 may include a high-resolution display screen 110, often formed of light emitting diodes (LEDs), organic light-emitting diodes (OLEDs) or liquid crystal displays (LCDs). Display screen 110 is positioned close to the eyes, may be comprised of two separate screens, one for each eye, or one large screen for both eyes, and is usually compact (on the order of 1 - 2.5 inches across). The near-eye display device 100 includes optical elements to provide user 10 with a wide field of view (FOV) and high image quality. Shown in FIGs. 1 A and 1 B is a focusing lens 120 to provide magnification of the display screen 110 to user 10. The lens may be lightweight and thin to prevent adding excessive weight.

[0039] Although not separately illustrated in Figures 1A-1 B, the near-eye display device 100 may include or be coupled to a processing device (as in the embodiment of FIG. 11 ). The display device 100 may be separate from or integrated within any portion of, or attached to, the frame of device 100. The near-eye display device 100, or a processing device incorporated therein or attached thereto, may include one or more visual sensors, audio sensors, position sensors, environment sensors, and the like. Examples of the sensors include cameras such as wide-angle cameras, infrared cameras, or the like; depth sensors such as Lidar (light detection and ranging); position sensors such as orientation sensors, magnetometers, or the like; motion sensors such as accelerometers, gravity sensors, gyroscopes, or the like; environment sensors such as light sensors, temperature sensors, humidity sensors, air pressure sensors, or the like; audio sensors such as microphones; medical sensors such as blood-oxygen sensors, brain wave sensors, pulse oximeter sensors, optical heart rate sensors, or the like; and / or satellite navigation sensors such as global positioning system (GPS) sensors; or the like. Near-eye display device 100 may include adjustable straps and padding for a secure fit, ventilation systems to prevent fogging, and audio components like headphones or speakers for spatial sound. Some devices also feature adjustable interpupil lary distance (IPD) mechanisms to ensure that the lenses align with the user's eyes, further enhancing comfort and reducing eye strain during prolonged use.

[0040] FIG. 2 illustrates the unity of rendering binocular display, such as would be used for the near eye display device 100. A binocular image is a pair of images that are viewed simultaneously through a binocular vision system, such as user 100 eyes. In FIG. 2 left and right eyes 201 L and 201 R are shown. When viewing a display, the eyes will be a distance “d” to the display screen 231 and separated by an interpupillary distance IPD. Locating the lens 120 within the display device 100 can incorporate the design of a human binocular vision model discussed below. For example, parameters can include average eye height of a human (men=1635mm, woman=1545mm), average IPD of a human (between 50 - 75 mm, with an average of 63mm), and average eye field of vision (142 degrees horizontal, 165 degrees vertical).

[0041] FIG. 3 illustrates image formation geometry for an immersive display in more detail. FIG. 3 illustrates a side view of an arrangement for an embodiment of a near eye display. An eye 701 is viewing a micro display 231 of height h’ through a lens 305 of focal length f that is separated from the micro display 231 by a distance of d’, where a micro display 231 and lens 305 are part of a head mounted display HMD 339. In the side view of FIG. 3, only the one eye and corresponding micro display and lens are shown, but a similar lens and micro display can be included in HMD 339 for the other eye. The eye 201 will perceive a virtual image 331 of height h at a distance from the lens of D.

[0042] In a near-eye binocular display such as FIGs. 1A, 1B, and 3, the image plane becomes the virtual image plane 331. The rendered display on the micro display panel 231 relates to deye. In most cases, since deye«D, system designs ignore the parameter deye. For example, a typical set of values are deye=10mm, D=500mm. In embodiments, deyecan be in a range of 9mm - 20mm.

[0043] FIG. 4 depicts an experimental setup utilized in evaluating the technology described herein. In FIG. 4, two display panels 460, 470 are positioned adjacent to two lenses 440, 450 for evaluation by an eye model 420, 430 coupled to a processing device 410. In embodiments disclosed herein, two types of displays were considered - one LCD and one OLED. The displays 460, 470 may comprise arrays of display elements (LCDs and OLEDs), each display element comprising a pixel. In one test, a 1000 (1 K) pixel LCD display comprises each display 460, 470, such as, for example,a BOE® VS019U0M-NH0-DKP0 (BOE Technology Group Co., Ltd.) having a size of 1.89” (diagonal), with 1600 x 1200 pixels, at a 24.0 pm pitch, with each subpixel at 10 pm x 5.8 pm, with a 0.4 pm wide gap between each subpixel. In another evaluation, each display panel 460, 470 comprises an OLED display such as a BOE® VX135KDP, having a 1.35”- diagonal size, with 3552 x 3840 pixels, a 7 pm subpixel pitch with a hexagonal pattern, and each subpixel having a diameter around 2.6 pm. For an OLED display, the emission central wavelengths for Red Green and Blue are, respectively, 611 nm, 527 nm, and 457nm, with full width at half maximum (FWHM) bandwidths of R 53nm, G 43nm, and B 25nm. Lenses 440, 450 may comprise a NTKJ® FE10, microlenses with a focal length f=10mm and 1 ,98mm pitch. In another test, a Thorlabs AC050 doublet lens with a focal length of f=10mm, a corrected dispersion and a maximum 5mm clear aperture (numerical aperture of 0.25) was used. In embodiments, as discussed herein, the present technology uses an acrylate microlens array, having a focal length of f=10mm, a clear aperture of D=2mm in each lens. The numerical aperture of each microlens unit is 0.1. (The numerical aperture (NA) of a lens is a measure of its ability to collect and focus light. NA can be calculated from the focal length (f) and diameter (D) of the lens: NA = D / (2f).

[0044] The models 440, 450 are based on the Arizona Eye Model which is a computer simulation of the human eye, comprising several components that mimic the optical and visual properties of the human visual system. The model includes the cornea, anterior chamber, lens, vitreous humor, retina and optic nerve. The model accounts for refractive errors, pupil size, accommodation and apparitions. The models 440, 450 are implemented by processor device 410. In the experimental setup of FIG. 4, the Arizona 2015 eye model (described in J. Schwiegerling, Field Guide to Visual and Ophthalmic Optics, SPIE Press, Bellingham, WA (2004)) was modified by shortening the thickness from the posterior lens to the retina, thereby shifting the eye model's reference wavelength from 589.29nm to 550nm. This modified Arizona eye model is referred to herein as the “AZ-modified” model.

[0045] FIG. 5A illustrates an emission spectrum for a conventional LCD or OLED display such as that evaluated in the test setup of FIG. 4. The wavelengths illustrated for the blue 501 , green 503 and red 505 spectra are exemplary. As illustrated therein, LEDs typically transmit on a narrow band of wavelengths, with the peaks of blue 501illustrated at approximately 450nm, 503 at 530nm and red 505 at 640nm, with full-with- at-half-maximum (FWHM) bandwidths on the order of 20 - 30 nm.

[0046] FIG. 5B illustrates a graph of the luminous efficiency of the eye. FIG 5B illustrates the Color and Vision Research Laboratories (CVRL) standardized cone vs. luminous efficiency for a human eye for red 601 , green 603 and blue 605 wavelengths, and showing 2-degree 609 and 10 degree 607 luminous efficiency. The CVRL provides standardized data related to human color vision, including spectral sensitivity functions for human cone photoreceptors. Cone cells are one of two types of photoreceptor cells found in the retinas of the eyes of many vertebrates, including humans. These cells are responsible for color vision. Humans typically have three types of cone cells, each sensitive to different wavelengths of light corresponding to red, green, and blue colors. Luminous efficiency refers to the effectiveness with which electromagnetic radiation, particularly light, produces a visual response in humans. It is a measure of how well a light source produces visible light as perceived by the human eye, considering that the eye has varying sensitivity to different wavelengths of light.

[0047] FIG. 5C illustrates an emission spectrum for a first embodiment of a display element in a display device in accordance with the described technology. In contrast to known, prior art systems which utilize ever smaller, more compact narrowing of the display RGB emission FWHM bandwidth to as low as 1 nm, the described technology uses wider bandwidths for display elements in the green and red spectrums. In embodiments, as illustrated in FIG. 5C, the green 601 and red 603 bandwidths are widened to a FWHM bandwidth of 70 nm (+ / - 15nm) for at least the green and red emission range. In another embodiment, both of these emission bands may have a FWHM of 80 nm + / - 5nm, or any combination of value approximate to these values. Thus, the FWHM of the green and red emission bands may range, for example from 60 nm to as much as 85 or 90 nm. In embodiments, the FWHN of the blue 605 emission range is 25nm (+ / - 10nm) or less. In other embodiments, the blue emission range may be widened as well.

[0048] Human eyes are wired to broad band light spectra, while display emissions are “narrow” bandwidth. In essence, the disclosed technology de-focuses vision to lower the resolution. To create LCD, LED or OLED devices having the requisitebandwidths, a broader green and red emission spectra may be created by controlling the materials used to create the display elements. In OLEDs, this is directly related to the emissive materials, while in LCDs, it may also involve the use of backlight and color filters. Manufacturing LCD and OLED screens to have a broader green and red emission involves using host materials for the green and red emission spectra combined with green-emitting phosphorescent or fluorescent dyes and / or adjusting the molecular structure of these dyes to broaden the emission spectrum. Similarly, adjusting the red emission spectrum involves incorporating red-emitting materials that have been chemically engineered to emit over a broader spectrum as defined herein. In edge-lit or direct-lit LCDs, one may use LEDs that emit a broad spectrum of light and can be achieved by using multiple phosphors that emit at different wavelengths within the green and red ranges.

[0049] The broadening of the FWHM bandwidth blurs the image on the display screen while reducing the screen door effect. This also increases the spot size -- the area on the retina where light from a single pixel on the screen is focused. The spot size of a display is proportional to the depth of focus. The described embodiments provide a larger spot size which results in a longer depth of focus thereby requiring less effort to focus on the part of a wearer.

[0050] In addition to the foregoing, or in the alternative thereto, in another embodiment, this defocusing of user vision is accomplished using optical elements in the near eye display device 100. By decreasing the peak-to-peak resolution of the display, the peak itself is broader, providing a larger depth of focus. In a near eye display, the distance from the eye to the display is fixed, but because it is desirable for the user to experience 3D effects, it is desirable for the display to have as large a depth of focus as possible.

[0051] Typical HMD displays have an optical element in the form of a focal lens within the display to allow the eye to focus on the display. FIGs. 6A and 6B show an exemplary commercial lens used in HMD devices and / or to test the described technology for use in HMD devices. One such lens 600 which was tested with the test setup of FIG. 4 was a Thorlab® AC050-10 lens with a clear aperture diameter D=5mm. The numerical aperture of such lens was 0.25.

[0052] The Thorlab® lens is illustrated in FIGs. 6A and 6B and comprises achromatic doublets comprising lens elements 610 and 620 which are optimized to provide a nearly constant focal length across a broad bandwidth. This is accomplished by utilizing a multi-element design to minimize the chromatic aberration of the lens. Dispersion in the first (positive) element 610 of the doublet is corrected by the second (negative) element 620, resulting in better broadband performance than spherical singlets or aspheric lenses.

[0053] In embodiments, the described technology achieves CPD by using a focusing lens with a lower numeric aperture than conventionally used in a near eye display device. "CPD" is a measure of the perfect absorption of light in an optical system, where incoming light waves are completely absorbed by a material without any reflection or transmission.

[0054] Such a reduced numeric aperture lens can comprise a dispersion correcting lens such as that shown in FIGs. 6A and 6B. In one embodiment, the aperture diameter of 5 mm of the Thorlab® lens is reduced to 2mm. The numerical apertures was reduced from 0.25 to 0.1 . In embodiments, this reduction can be achieved by applying a mechanical cover or coating to the lens to reduce the aperture. In other embodiments, a focusing lens may be manufactured with the reduced size aperture.

[0055] In further embodiments, a focusing lens without dispersion correction can be used. Using a single element lens, the dispersion is not corrected. For example, an acrylate microlens array, having a focal length f=10mm and an aperture (A) diameter D=2mm may be used. Such dispersion would further augment the dispersion or defocus on eye retina. Thus, for an OLED display with RGB peaks at 505.5 nm, 527 nm, and 548.5nm, the combined peak resolution is around 42 CPD. If the bandwidth is broadened to 80nm, the peak resolution drops to less than 35 CPD. This measure of 35 CPD (or 70 pixel per degree) is a resolution that current display technology can reach.

[0056] Experimental results were obtained using the Thorlab® AC050-10-A doublet lens which corrects the dispersion in visible wavelength and has nominal focal length of 10mm. This lens was modified to have a clear aperture of 5mm and 2mm. In the experiment setup, the distance from a 4K OLED display system was fixed andmodeled the aforementioned displays using the modified Arizona model, with eye accommodation as variable. Based on BOE® OLED display’s central wavelength at 527nm and full-width-half-maximum bandwidth of 43nm, the PSF’s of three wavelengths: 505.5 nm, 527 nm, and 548.5nm were modeled, and then overlapped the three wavelengths with the weight of eye sensitivity, respectively, 0.2185, 0.821 , 0.4935, according to CVRL cone sensitivity to calculate the averaged PSF. From the average PSF, the MTF of the combined spot was calculated.

[0057] FIGs. 6C and 6D illustrate two types of multi-element lenses which may comprise pancake lenses suitable for use in HMD displays. Pancake lenses are a lens module that uses a folded optical path to make the total length of the optical path shorter. FIG. 6C illustrates a first type of pancake lens where each of the lens elements is sandwiched together. The lens includes a first element 622, second element 624 and third element 624. As illustrated in FIG. 6C, the collection of lens elements and (optionally) film layers are tightly packed together, using the interaction between the film layers to make the previously only straight light path of light reflected between the film layers again and again. The structure minimizes light loss and reflections between lenses, enhancing the overall visual experience. FIG. 6D illustrates a second type of pancake lens where light refracts through element 632, element 634 and element 634, further refining the image quality and reducing optical aberrations. Each of the multilens structures may be used in an HMD device in accordance with the described technology.

[0058] FIG 7 illustrates a plot of the resolution in cycles per degree when the MTF (modulation transfer function) dropped to 20%. When the Thorlab® AC050 lens at 5mm clear aperture, the peak eye resolution was around 70 CPD. When the aperture diameter is reduced to 2mm, the peak resolution dropped to 48 CPD as illustrated in FIG. 8.

[0059] FIGs. 9 and 10 illustrated the effect of widening the FWHM of the red and green bands of the display elements in the micro display. FIG. 9 shows the spatial frequency in cycles per degree at MTF dropping to 0.2 with acrylate single element lens D=2mm clear aperture for green light central emission 527nm and 43nm FWHM bandwidth, and green light central emission 550nm and 80nm FWHM bandwidth.

[0060] A by-product of these embodiments is that the display depth of focus has expanded when the peak resolution has been lowered. As understood, as long as the eye retina image is higher than 5 cycles per degree, that eye can accommodate the VAC (vergence accommodation contraction). Using doublet at 5mm clear aperture and 43nm OLED green emission bandwidth, the above 8 CPD accommodation range is from 1.5625 to 2.875 diopter or 1.3 diopters. While using two strategies of 2mm clear aperture and 80nm emission bandwidth, the above 8 CPD accommodation range would become 1.75 to 4.375 diopter or 2.63 diopters. This effectively doubles the depth of focus. By optimizing the depth of focus, more natural depth cues may better align with the human visual system's vergence and accommodation responses thereby reducing the vergence-accommodation conflict.

[0061] FIG. 11 illustrates a network processing device 1100 which may comprise a near eye display device comprising an AR / VR processing device implementing the technology discussed herein. The network processing device 1100 may be integrated into a headset 100a or may be provided in a housing which is separate from but connected to the headset 100a comprising a near-eye display device as discussed herein.

[0062] Device 1100 may comprise a central processing unit (CPU) 1110, a graphics processing unit (GPU) 1120, a memory 1125, a mass storage device 1130, and an I / O interface 1115 connected to a bus 1170. The I / O interface 1115 may be connected to a headset 100a where the components of the network processing device are illustrated in FIG. 11 are not integrated with the headset 100a. The bus 1170 may be one or more of any type of several bus architectures including a memory bus or memory controller, a peripheral bus, or the like. A network interface 1135 enables the network processing device to communicate over a network 1000 with other processing devices such as those described herein. In embodiments, network processing device 1100 may contain multiple instances of a component, such as multiple processing units, processors, memories, interfaces, etc.

[0063] The mass storage device 1130 may comprise any type of storage device configured to store data, programs, and other information and to make the data, programs, and other information accessible via the bus 1170. The mass storage device 1130 may comprise, for example, one or more of a solid-state drive, hard diskdrive, a magnetic disk drive, an optical disk drive, or the like. The mass storage device 1130 includes instructions which when executed by the CPU (or processor) cause the processor to perform the methods described herein. The mass storage 1130 may include code in the form of application modules 1134 stored thereon, comprising instructions for causing the CPU to implement the components of natural movement application which are illustrated as present in memory 1125 in FIG. 11.

[0064] The CPU 1110 may comprise any type of electronic data processor. Memory 1125 may comprise any type of system memory such as static randomaccess memory (SRAM), dynamic random-access memory (DRAM), synchronous DRAM (SDRAM), read-only memory (ROM), a combination thereof, or the like. In an embodiment, memory 1125 may include ROM for use at boot-up, and DRAM for program and data storage for use while executing programs. In embodiments, the memory 1125 is non-transitory. In one embodiment, the memory 1125 includes computer-readable instructions that are executed by the processor(s) 1110 and 1120 to implement embodiments of the disclosed technology.

[0065] In one embodiment, the memory 1125 includes instances of various AR / VR applications 1150, and an image generator 1155. Stored versions of each of these components may be provided in mass storage 1130 in application modules comprising code instructing the CPU and GPU to implement applications and images associated with the applications on the display screens discussed herein.

[0066] Human visual panel tests on 1 K-resolution-2” LCD and 4K-resolution-1.35” OLED microdisplays confirmed that lowering the display system peak resolution, reducing the aperture size of the focusing lens, and / or removing dispersion correction in the lens, made the display images more continuous and enabled long range depth- of-focus.

[0067] Although the technology is described with respect to display screens shown in front of user’s eyes, in near eye displays for augmented reality devices, display elements may be positioned out of the line of vision of a user’s eye and images transmitted to a see-through, partially reflective panel in front of the eye using, for example, waveguides. In such systems, the disclosed FWHM bandwidths used herein can be generated in the display drivers (generally LED or OLED) and used inaugmented reality systems. As such, a display screen may comprise a microdisplay or a partially reflective, partially transmissive panel in front of the eye. The display screen does not include the display optics (e.g. a focusing lens) which may comprise a single focusing lens or multiple-element lenses.

[0068] It is understood that the present subject matter may be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein. Rather, these embodiments are provided so that this subject matter will be thorough and complete and will fully convey the disclosure to those skilled in the art. Indeed, the subject matter is intended to cover alternatives, modifications and equivalents of these embodiments, which are included within the scope and spirit of the subject matter as defined by the appended claims. Furthermore, in the following detailed description of the present subject matter, numerous specific details are set forth in order to provide a thorough understanding of the present subject matter. However, it will be clear to those of ordinary skill in the art that the present subject matter may be practiced without such specific details.

[0069] Aspects of the present disclosure are described herein with reference to flowchart illustrations and / or block diagrams of methods, apparatuses (systems) and computer program products according to embodiments of the disclosure. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable instruction execution apparatus, create a mechanism for implementing the functions / acts specified in the flowchart and / or block diagram block or blocks.

[0070] The description of the present disclosure has been presented for purposes of illustration and description but is not intended to be exhaustive or limited to the disclosure in the form disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the disclosure. The aspects of the disclosure herein were chosen and described in order to best explain the principles of the disclosure and the practical application, and toenable others of ordinary skill in the art to understand the disclosure with various modifications as are suited to the particular use contemplated.

[0071] Although the subject matter has been described in language specific to structural features and / or methodological acts, it is to be understood that the subject matter defined in the appended claims is not necessarily limited to the specific features or acts described above. Rather, the specific features and acts described above are disclosed as example forms of implementing the claims.

Claims

CLAIMSWhat is claimed is:1 . A near-eye display device system, comprising: a first lens; a display screen having a red, green, blue (RGB) emission spectra comprising a red emission band having a full width half maximum of 70 nm + / - 15nm, and a green emission band having a full width half maximum 70 nm + / - 15nm, and a frame supporting the first lens between a first eye of a user and the display screen.

2. The near-eye display device system claim 1 , wherein the display screen has a blue emission band having a full width half maximum 30 nm or less.

3. The near-eye display device system of claim 1 wherein the RGB emission spectra comprises a red emission band having a full width half maximum of 80 nm + / - 5nm, and a green emission band having a full width half maximum 80 nm + / - 5nm.

4. The near eye display device system of claim 1 wherein the first lens comprises a multi-element lens.

5. The near-eye display device system of any of claims 1 through 4 wherein the first lens has a dispersion correction lens and has a numerical aperture of 0.25 or less.

6. The near-eye display device system of any of claims 1 through 4 wherein the first lens has is a dispersion correction lens and has a numerical aperture of 0.1 or less.

7. The near eye display device system of claim 1 wherein the first lens comprises a single element lens.

8. The near-eye display device system of any of claims 2 or 7 wherein the first lens has no dispersion correction and has a numerical aperture of 0.25 or less.

9. The near-eye display device system of any of claims 2 or 7 wherein the first lens has no dispersion correction and has a numerical aperture of 0.1 or less.

10. The near-eye display device system of claim 2 wherein the first lens is a microlens array having no dispersion correction.11 . The near-eye display device system of any of claims 1 through 10 further including a processor configured to: render images for presentation on the display screen.

12. The near-eye display device system of any of claims 1 through 11 further comprising: a second lens, a frame supporting the second lens in front of a second eye of a user and at least the display screen.

13. The near-eye display device system of any of claims 1 through 12 wherein the display screen comprises a first display screen associated with the first eye and first lens and a second display screen associated with the second eye and second lens.

14. The near-eye display device of any of claims 1 - 13 wherein each display screen is a microdisplay.

15. The near-eye display device of any of claims 1 - 12 wherein each display screen is a partially transmissive and partially reflective panel.

16. A near-eye display device system, comprising: a first lens; a display screen having a red, green, blue (RGB) emission spectra;a frame supporting the first lens at a position between a first eye of a user and the display screen; and wherein the first lens has a dispersion correction lens and has a numerical aperture of 0.1 or less.

17. The near eye display device system of claim 16 wherein the first lens comprises a multi-element lens.

18. The near-eye display device system of any of claims 16 or 17 wherein the RGB emission spectra comprising a red emission band having a full width half maximum of 70nm + / - 15nm, and a green emission band having a full width half maximum 70 nm + / - 15nm.

19. The near-eye display device system of any of claims 16 through 18, wherein the display screen has a blue emission band having a full width half maximum 30 nm or less.

20. The near-eye display device system of claims 16 through 19 wherein the RGB emission specta comprises a red emission band having a full width half maximum of 80 nm + / - 5nm, and a green emission band having a full width half maximum 80 nm + / - 5nm.21 . The near-eye display device system of any of claims 16 through 20 further including a processor configured to: render images for presentation on the display screen.

22. The near-eye display device system of any of claims 16 through 21 further comprising: a second lens, a frame supporting the second lens between a second eye of a user and the display screen;wherein the second lens has a dispersion correction lens and has a numerical aperture 0.1 or less.

23. The near-eye display device system of any of claims 16 through 22 wherein the display screen comprises a first display screen associated with the first eye and first lens and a second display screen associated with the second eye and second lens.

24. The near-eye display device of any of claims 16 through 23 wherein each display screen is a microdisplay.

25. The near-eye display device of any of claims 16 through 22 wherein each display screen is a partially transmissive and partially reflective panel.

26. A near-eye display device, comprising: a first lens; a frame supporting the first lens in front of a first eye of a user; a display screen having a red, green, blue (RGB) emission spectra; and wherein the first lens has no dispersion correction and has a numerical aperture of 0.25 or less.

27. The near-eye display device of claim 26 wherein the RGB emission spectra comprising a red emission band having a full width half maximum of 70 nm + / - 15nm, and a green emission band having a full width half maximum 70 nm + / - 15nm.

28. The near-eye display device system of claims 26 through 27 wherein the RGB emission spectra comprises a red emission band having a full width half maximum of 80 nm + / - 5nm, and a green emission band having a full width half maximum 80 nm + / - 5nm.

29. The near-eye display device of any of claims 26 through 28, wherein the display screen has a blue emission band having a full width half maximum 30 nm or less.

30. The near eye display device system any of claims 26 through 28 wherein the first lens comprises a single element lens.31 . The near-eye display device of any of claims 26 through 28 wherein the first lens is a microlens array having no dispersion correction.

32. The near-eye display device of any of claims 26 through 30 further including a processor configured to: render images for presentation on the display screen.

33. The near-eye display device of any of claims 26 through 32 further comprising: a second lens, a frame supporting the second lens in front of a second eye of a user; wherein the second lens has no dispersion correction and has a numerical aperture of 0.25 or less.

34. A user equipment device, comprising: a first lens; a frame supporting the first lens in front of a first eye of a user; a display screen having a red, green, blue (RGB) emission spectra; a storage medium comprising computer instructions; one or more processors coupled to communicate with the storage medium, wherein the one or more processors execute the instructions to cause the device create an image on the display screen; wherein the emission spectra of the display screen comprising a red emission band having a full width half maximum of 70 nm + / - 15nm, and a green emission band having a full width half maximum 70 nm + / - 15nm.

35. The user equipment device of claim 24 wherein the display screen has a blue emission band having a full width half maximum 30 nm or less.

36. The user equipment device of claim 34 wherein the emission spetra of the display screen comprises a red emission band having a full width half maximum of 80 nm + / - 5nm, and a green emission band having a full width half maximum 80 nm + / - 5nm.

37. A user equipment device, comprising: a first lens; a frame supporting the first lens in front of a first eye of a user; a display screen having an RGB emission spectra; a storage medium comprising computer instructions; one or more processors coupled to communicate with the storage medium, wherein the one or more processors execute the instructions to cause the device create an image on the display screen; wherein the first lens includes a dispersion correction and has a numerical aperture 0.1 or less.

38. A user equipment device, comprising: a first lens; a frame supporting the first lens in front of a first eye of a user; a display screen having an RGB emission spectra; a storage medium comprising computer instructions; one or more processors coupled to communicate with the storage medium, wherein the one or more processors execute the instructions to cause the device create an image on the display screen; wherein the first lens includes no dispersion correction and has a numerical aperture 0.25 or less.

39. The user equipment device of any of claims 37 or 38 wherein the emission spectra of the display screen comprising a red emission band having a full width half maximum of 70 nm + / - 15nm, and a green emission band having a full width half maximum 70 nm + / - 15nm.

40. The user equipment device of claim 39 wherein the display screen has a blue emission band having a full width half maximum 30 nm or less.

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