Head-mounted display device with vision correction

Abstract

The invention relates to a head-mounted display device with vision correction. A head mounted display may include a display system and an optical system in a housing. The display system may have a display that produces an image. A locator may be used to move the display relative to an eye position of an eye of a user. The adjustable optical system may include an adjustable lens, such as an adjustable cylindrical liquid crystal lens. When the user's eyes are in the eye position, the display may be viewed through the lens. A sensor may be incorporated into a head mounted display to measure refractive errors of a user's eye. The sensor may include a waveguide and a volume hologram and a camera for collecting light reflected from the retina of the user's eye. Viewing comfort may be improved by adjusting display position relative to eye position and / or by adjusting lens settings based on content presented on the display and / or measured refractive error.

Description

[0001] This application is a divisional application of the invention patent application with application date of May 3, 2018, application number 202111337486.4, and invention name “Head-mounted display device with vision correction”.

[0002] This patent application claims priority to provisional patent application 62 / 507,671 filed on May 17, 2017, which is hereby incorporated by reference in its entirety. Background Art

[0003] The present invention relates generally to optical systems, and more particularly to optical systems for head mounted devices.

[0004] Head-mounted devices such as virtual reality glasses and augmented reality glasses use displays to generate images and lenses to present the images to the user's eyes.

[0005] If care is not taken, head mounted devices can be very cumbersome and fatiguing to wear. Optical systems used for head mounted devices can be cumbersome and awkward, and may not be adequately adjustable. Extended use of a head mounted device with this type of optical system can be uncomfortable. Summary of the invention

[0006] A head mounted display device may include a display system and an optical system in a housing. The display system may have a display that generates an image. A positioner may be used to move the display relative to the user's eyes. The positioner may be used to adjust the horizontal distance of the displays from each other to accommodate differences in pupil distance between users, may be used to make vertical display position adjustments to accommodate differences in facial anatomy between users, and may be used to adjust the distance from the eyes to the display to change the focus.

[0007] The optical system may include an adjustable lens, such as an adjustable cylindrical liquid crystal lens. The display may be viewed through the lens. The optical system may include a fixed spherical lens used in conjunction with the adjustable cylindrical lens.

[0008] Sensors may be incorporated into the head mounted device to measure the refractive error of the user's eye. Viewing comfort may be improved by adjusting the display position relative to the eye position of the user's eye and / or adjusting the lens settings based on the content presented on the display and / or based on the measured refractive error of the eye. The sensors may include a waveguide and a volume hologram and a camera for collecting light reflected from the retina of the user's eye. Refractive errors such as hyperopia, myopia, and astigmatism may be corrected by tuning the lens and / or adjusting the display position. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1is an illustration of an illustrative head mounted device according to one embodiment.

[0010] Figure 2 is an illustration of an illustrative head mounted device with an adjustable display and lenses according to one embodiment.

[0011] Figure 3 is a cross-sectional side view of an illustrative adjustable lens according to one embodiment.

[0012] Figure 4 is to show how the Figure 3 Illustration of the refractive index of a lens.

[0013] Figure 5 is a diagram showing how to adjust when forming a Fresnel lens according to an embodiment. Figure 3 Illustration of the refractive index of a lens.

[0014] Fig. 6A is an illustration of an illustrative Shack-Hartmann sensor for a head mounted device according to one embodiment.

[0015] Figure 6B , Figure 6C and Fig.6D is a diagram of an alternative light source for a Shack-Hartmann sensor, according to an embodiment.

[0016] Fig. 7A and Figure 7B is a diagram of a source portion and a detector portion of a Tscherning sensor according to one embodiment.

[0017] Fig. 8A and Figure 8B is a diagram of a source portion and a detector portion of a ray tracing sensor according to one embodiment.

[0018] Fig. 9 is a flow chart of illustrative operations involved in operating a head mounted device according to an embodiment.

[0019] Fig.10 is a side view of an exemplary lens and associated vision correction lens according to one embodiment.

[0020] Fig.11 is a front view of an illustrative vision correction lens coupled to a lens holder according to one embodiment.

[0021] Fig.12 is a side view of an exemplary lens and associated Fresnel vision correction lens according to one embodiment.

[0022] Fig.13 is a front view of an illustrative spherical Fresnel lens according to one embodiment.

[0023] Fig.14 is a front view of an illustrative cylindrical Fresnel lens according to one embodiment. DETAILED DESCRIPTION

[0024] Head-mounted devices such as head-mounted displays can be used in virtual reality and augmented reality systems. For example, a pair of virtual reality glasses worn on a user's head can be used to provide virtual reality content to the user.

[0025] Figure 1 An exemplary system is shown in FIG. 1 , in which a head mounted device such as a pair of virtual reality glasses is used to provide virtual reality content to a user. Figure 1 As shown, head mounted display 10 may include a display system such as display system 40 that forms an image and may have an optical system such as optical system 20 through which a user (e.g., a user's eye 46) may view the image produced by display system 40 in direction 48.

[0026] Display system 40 may be based on a liquid crystal display, an organic light emitting diode display, a display having an array of crystalline semiconductor light emitting diode dies, a liquid crystal on silicon display, a micro-electromechanical system (MEM), and / or a display based on other display technologies. Separate left and right displays may be included in system 40 for the user's left and right eyes, or a single display may span both eyes.

[0027] Virtual content (e.g., image data for still and / or moving images) may be provided to the display system 40 using control circuitry 42 installed in the head mounted device 10 and / or control circuitry installed external to the head mounted device 10 (e.g., associated with a portable electronic device, laptop computer, or other computing device). The control circuitry 42 may include storage devices such as hard disk storage devices, volatile and non-volatile memory, electrically programmable storage devices used to form solid state drives, and other memories. The control circuitry 42 may also include one or more microprocessors, microcontrollers, digital signal processors, graphics processors, baseband processors, application specific integrated circuits, and other processing circuits. Communication circuitry in the circuitry 42 may be used to transmit and receive data (e.g., wirelessly and / or via a wired path). The control circuitry 42 may use the display system 40 to display visual content, such as virtual reality content (e.g., computer-generated content associated with a virtual world), pre-recorded video or other images for a movie or other media.

[0028] System 40 may include an electronically controlled positioner that may be used to adjust the position of a display in system 40. Lens system 20 may include an adjustable lens. During operation, control circuitry 42 may make positional adjustments to a display in system 40, may adjust an adjustable lens in lens system 20, and / or may make other adjustments to components of device 10 when using system 40 to present image content to a user.

[0029] Input-output devices 44 may be coupled to control circuitry 42. Input-output devices 44 may be used to collect user input from a user, may be used to measure the environment surrounding device 10, may be used to provide output to a user, and / or may be used to supply output to an external electronic device. Input-output devices 44 may include buttons, joysticks, keypads, keyboard keys, touch sensors, track pads, displays, touch screen displays, microphones, speakers, light emitting diodes for providing visual output to a user, sensors (e.g., force sensors, temperature sensors, magnetic sensors, accelerometers, gyroscopes, and / or other optical sensors for measuring the orientation, position, and / or movement of glasses 10, proximity sensors, capacitive touch sensors, strain gauges, gas sensors, pressure sensors, ambient light sensors, and / or other sensors). If desired, input-output devices 44 may include a sensing system for measuring eye characteristics of a user's eye 46. For example, a wavefront sensor (such as a Shack-Hartmann wavefront sensor, a Tscherning sensor, or a ray-tracking sensor) may be used to measure refractive errors in the user's eyes, such as astigmatism, hyperopia, and myopia. The device 44 may also include a camera (digital image sensor) for capturing images of the user's surroundings, a camera for performing gaze detection operations by viewing the eye 46, and / or other cameras.

[0030] Figure 2 is along Figure 1 Direction 48 (along Figure 2 FIG. 1 is a diagram of a portion of the head mounted device 10 viewed along the Z axis in FIG. Figure 2As shown, optical system components (such as left lens 20L and right lens 20R) and display system components (such as left display 40L and right display 40R for device 10) can be mounted in a housing such as housing 12. Housing 12 can have the shape of a frame for a pair of glasses (e.g., head mounted device 10 can resemble glasses), can have the shape of a helmet (e.g., head mounted device 10 can form a helmet mounted display), can have the shape of a pair of swimming goggles, or can have any other suitable housing shape that allows housing 12 to be worn on the head of a user. The following configuration may sometimes be described herein as an example: when the user views optical system 20 and display system 40 in direction 48, housing 12 supports optical system 20 and display system 40 in front of the user's eyes (e.g., eye 46). If desired, housing 12 can have other suitable configurations.

[0031] Housing 12 may be formed of plastic, metal, fiber composites such as carbon fiber materials, wood and other natural materials, glass, other materials, and / or combinations of two or more of these materials. Electronically controlled positioners (e.g., computer-controlled stepper motors, piezoelectric actuators, or other computer-controlled positioning devices controlled by control signals from control circuitry 42) may be coupled to components of device 10 and used to position the components at desired locations relative to housing 12 and relative to a user wearing device 10. For example, positioner 50X may be used to adjust the positions of respective X-axes of displays 40L and 40R. Positioner 50Y may be used to adjust the X-axes of displays 40L and 40R along the X-axis. Positioner 50Y may be used to adjust the X-axes of displays 40L and 40R along the X-axis. Figure 2The Y-axis of the device 10 adjusts the corresponding position of the displays 40L and 40R. The Z-axis position of the displays 40L and 40R (the distance from the displays 40L and 40R to the user's left eye and right eye 46, respectively) can be adjusted using the positioner 50Z. The positioner 50L (e.g., an X-axis, Y-axis, Z-axis and / or rotational positioner) can be used to adjust the position of the lenses 20L and 20R. The lens properties can also be electrically tuned in response to a control signal from the control circuit 42. The positioner in the device 10 can be coupled to the housing 12 (e.g., to move the position of the component relative to the housing 12) and / or can be coupled to a movable structure in the device 10 (e.g., to adjust the position of one component relative to another component or relative to a movable support structure). If desired, the lens 20L can be coupled to the display 40L using a fixed support structure, and the lens 20R can be coupled to the display 40R using a fixed support structure so that the display and the corresponding lens move together. In other configurations, the position of lenses 20L and 20R can be fixed (or adjustable) relative to the user's eyes, while the position of displays 40L and 40R relative to the user's eyes can be independently adjusted using positioners of displays 40L and 40R. In some arrangements, lens positioners 50L can be omitted. Arrangements in which lens positioners only provide rotational positioning of lenses 20L and 20R can also be used.

[0032] Adjustability of the position of displays 40L and 40R and / or lenses 20L and 20R along the Z-axis allows the image on displays 40L and 40R to be focused for the user. Inward and outward position adjustment parallel to the X-axis allows device 10 to accommodate users with different interpupillary distances. Each lens and faceplate pair (corresponding to one eye) must be adjusted together. Adjustment along the Y dimension allows device 10 to accommodate differences in user head and facial anatomy (e.g., placing displays and lenses at different heights relative to the user's eyes along the Y-axis). Positioner operation may be controlled in response to user input. For example, control circuitry 42 may use Figure 2 The locator is based on button press input, touch sensor input, voice input, on-screen menu selection, and / or Figure 1 Position adjustments may be made based on other user inputs from the device 44. Position adjustments (eg, for focusing) may also be made automatically by the control circuit 42 based on measured refractive properties of the user's eye.

[0033] In addition to using lens movement and / or display movement to perform focusing operations, lenses 20L and 20R may be electrically tuned based on control signals from control circuitry 42. Lenses 20L and 20R may be, for example, tunable lenses, such as tunable liquid crystal lenses or other lenses that may be dynamically tuned to exhibit different focal lengths. Figure 3In the example of FIG. 1 , the tunable lens 20T (e.g., lens 20L and / or lens 20R) has been formed by a pair of orthogonally oriented stacked tunable cylindrical lenses. Specifically, the tunable lens 20T has a first tunable cylindrical lens CL1 and a second tunable lens CL2 formed by a liquid crystal lens structure. A polarizer (e.g., a linear polarizer with aligned transmission axes) may be placed above CL2 and below CL1.

[0034] Lens 20T may include a substrate such as substrate 52. Substrate 52 may be formed of light-transmitting plastic, transparent glass, or other suitable transparent materials. Transparent conductive electrodes such as electrodes 54, 56, 58, and 60 may be formed on substrate 52. The transparent conductive electrodes may be formed of indium tin oxide or other transparent conductive materials. Photolithography and etching, shadow mask patterning, or other patterning techniques may be used to pattern the electrodes into a desired shape (e.g., rings, strips, pads in an array, etc.).

[0035] exist Figure 3 In one exemplary configuration shown, the lower electrode 54 of the adjustable cylindrical lens CL1 is formed of a blanket layer of transparent conductive material, while the upper electrode 56 of the adjustable cylindrical lens CL1 is formed of a patterned strip of transparent conductive material extending parallel to the Y axis. Liquid crystal material 62 is interposed between the electrodes 54 and 56. The refractive index of the liquid crystal material changes with an applied voltage (electric field through the liquid crystal). By independently adjusting the voltage on each electrode 56 across the dimension X, the refractive index of the liquid crystal material 62 can be adjusted under each electrode 56, and thus the focal length of the cylindrical lens CL1 can be adjusted.

[0036] Since the electrode 56 is along Figure 3 The Y-axis of the upper adjustable cylindrical lens CL2 extends, so the elongated axis of the cylindrical lens CL1 also extends parallel to the Y-axis. In the upper adjustable cylindrical lens CL2, the liquid crystal material 64 is interposed between the electrode 60 and the electrode 58. The electrode 58 can be a uniform layer of transparent conductive material, and the upper electrode 60 can be formed by patterned transparent conductive material strips extending parallel to the X-axis. By adjusting the voltage applied to the electrode strips of the electrode 60, the focal length of the adjustable cylindrical lens CL2 can be adjusted. The electrode strips of the electrode 60 extend along the X-axis, so the longitudinal axis of the lens CL2 also extends along the X-axis. Because the lenses CL1 and CL2 are perpendicular to each other, the cylindrical lens optical power selected in the orthogonal direction can be generated by tuning the lenses CL1 and CL2. The spherical lens optical power can be generated by parametrically driving both CL1 and CL2 (electrodes in X and Y).

[0037] Figure 4 is a diagram showing how the focal length of an adjustable cylindrical lens (e.g., the focal length of CL1) can be adjusted. In a first configuration, a smoothly varying voltage profile is applied to the electrode strips of the adjustable cylindrical lens so that the refractive index n of the lens is determined by Figure 4The refractive index profile 66 is characterized by the value of the refractive index n varying in a curved shape across the dimension X, thereby making a cylindrical lens from the liquid crystal material.

[0038] To tune the lens, another smoothly varying voltage profile (e.g., having a larger magnitude) may be applied to the liquid crystal material, thereby producing refractive index profile 68. As shown in these examples, the refractive index profile of the adjustable cylindrical lens may be dynamically adjusted to adjust the focal length of the lens (e.g., having a longer focal length and a weaker lens optical power as shown in profile 66, or having a shorter focal length and a stronger lens optical power as shown in profile 68). If desired, the refractive index profile of the adjustable cylindrical lens may be dynamically adjusted to adjust the focal length of the lens (e.g., having a longer focal length and a weaker lens optical power as shown in profile 66, or having a shorter focal length and a stronger lens optical power as shown in profile 68). Figure 5 The adjustable cylindrical lens refractive index profile 70 may be a type of refractive index profile to achieve a cylindrical lens of desired optical power using a Fresnel lens configuration.

[0039] In an adjustable lens configuration of the type shown in lens 20T, the longitudinal axes of lenses CL1 and CL2 are orthogonal, allowing a cylindrical lens to be dynamically generated along the X or Y axis. To help correct the vision of a user with astigmatism, lenses CL1 and CL2 of adjustable lens 20T can be used to control the cylindrical lens optical power along the X and / or Y dimension. If desired, the adjustable cylindrical lens can be rotated using a positioner. For example, lens system 20 may include a mechanically or electrically rotatable cylindrical adjustable lens that varies optical power (e.g., to compensate for eye astigmatism that is asymmetric about the X or Y axis). Configurations that fix the angular orientation of lens 20T and use electrical tuning to tune lens CL1 and / or lens CL2 are described herein as examples.

[0040] Lens system 20 may include a fixed (or adjustable) spherical lens aligned with lens 20L and a fixed (or adjustable) spherical lens aligned with lens 20R. When the spherical lens is combined with an adjustable cylindrical lens, device 10 can adjust the adjustable lenses in system 20 to correct the vision of the user's eye using an equivalent sphere (e.g., a combination of a spherical lens and a cylindrical lens, with appropriate optical power, can approximate the required aspherical lens to correct the user's astigmatism).

[0041] If desired, control circuitry 42 may automatically measure the refractive error of the user's eye using a sensor configured to function as an aberrometer (e.g., a Shack-Hartmann, Tscherning, or ray-tracing sensor or other suitable refractive error measurement device). Fig. 6A Other structures of the type shown in can be used to form a wavefront sensor, so that the size of the wavefront sensor can be reduced sufficiently to be carried in the head-mounted device 10.

[0042] Device 10 may include a display such as Fig. 6AEach display 40 may have an array of pixels P for generating an image. Figure 2 As depicted, device 10 may have two displays (e.g., displays 40L and 40R) for providing images to the user's left eye and right eye 46, respectively. Fig. 6A In the example of FIG. 4 , only one eye 46 and a corresponding display 40 are shown.

[0043] Figure 2 A position sensor of the type shown in can be used to adjust the position of display 40 relative to eye 46 so that the image is clear and can be viewed comfortably by the user. For example, the spacing between display 40 and eye 46 can be adjusted using a Z-axis positioner (as an example). Lens system 20 may include fixed and / or adjustable lenses (e.g., fixed and / or adjustable spherical lenses, adjustable cylindrical lenses, etc.).

[0044] exist Fig. 6A In a Shack-Hartmann sensor configuration of the type shown in FIG. 1 , a light source 72 and a camera 106 may be used to supply light to the eye 46 and to measure reflected light to measure optical properties of the eye 46. The light source 72 may generate light 74 of any suitable wavelength. For example, the light source 72 may be an infrared light source such as a laser or a light emitting diode that generates near infrared light (e.g., light of 750 to 1400 nm, light of at least 700 nm, light of at least 750 nm, light of at least 800 nm, light of less than 1500 nm, light of less than 1000 nm, light of less than 900 nm, or light of less than 850 nm, etc.). Other wavelengths of light (longer infrared wavelengths, visible wavelengths, etc.) may also be used if desired.

[0045] For a light source such as a laser, an objective lens 75, a pinhole aperture 76, a collimating lens 80, and an iris 81 can be used to collimate and control the beam size of the light 74. These optical elements constitute the collimating optical assembly 71. The objective lens 75 focuses the light 74 onto the pinhole aperture 76, which acts as a spatial filter to eliminate uneven intensity distribution in the light beam. A light beam with a smooth Gaussian distribution is emitted from the pinhole aperture 76. The lens 80 can be used to collect and collimate the spatially filtered light. The iris 81 can be used to control the size of the collimated light beam. The lenses and apertures in the assembly 71 can be fixed components, or can be adjusted manually or electronically in response to control signals from the control circuit 42.

[0046] The light source 72 may be a light emitting diode (LED) 73 emitting at any suitable wavelength. Due to the limited size of the LED, the light beam will diverge slightly after collimation. For LED light sources, the collimation optical assembly 71 may include different components to mitigate the divergence of the light beam after collimation. Figure 6BAn arrangement is shown in which an aspheric lens pair 77A collimates light 74 from an LED source 73. If desired, a single aspheric lens may be used for collimation. Figure 6C In , the collimating optical assembly 71 may contain only the LED 73 and the compound parabolic concentrator 77B. By sitting at the focus of the hollow parabolic mirror 77C, the light 74 may be collected and collimated. The parabolic concentrator 77B is advantageous in cases where the LED source 73 carries a large emission distribution that cannot be fully captured by a simple lens. Fig.6D In the embodiment of the present invention, assembly 71 may include lens array pair 77C and condenser lens 79. The combination of the two lens arrays produces uniform illumination, the beam size of which can be controlled by condenser lens 79. If desired, a single lens array may be used instead.

[0047] Input and output couplers such as volume holograms or other holographic couplers can be used to couple light into and out of the ends of waveguides 84 and 94. The couplers are directional, meaning that light can enter the volume hologram in one direction. For example, input coupler 82 can be used to couple light 74 into waveguide 84. Once coupled into waveguide 84, the light can travel in direction 93 within waveguide 94 to output coupler 86. Output coupler 86 can be aligned with the user's eye 46 (e.g., output coupler 86 can be interposed between display 40 (with lens 20) and the user's eye 46). With this configuration, output coupler 86 couples light traveling in direction 93 in waveguide 94 out of waveguide 94 and propagates toward eye 46, as shown by output light 88. This illuminates the user's eye with light 74. After passing through the lens of eye 46, light 88 is reflected in direction 48, as shown by reflected light 90. Input coupler 92 couples light 90 into waveguide 94. Couplers 86 and 92 may be tuned to the wavelength of light 74 and may therefore be transparent to the user when the user is viewing an image on display 40 in direction 48 .

[0048] In the waveguide 94, the light collected from the input coupler 92 travels in the direction 96 to the output coupler 83. The output coupler 83 couples the light that exits the waveguide 94 traveling in the direction 96 as output light 91 to the camera 106. The output light 91 passes through the lens 98, the low pass filter 100 (located at the focal point of the lens 98 and used to filter out noise in the light), and the lenslet array 102. The lenslet array 102 may include a two-dimensional array of lenses. These lenses focus the light 91 onto the camera 106 (e.g., a digital image sensor) in a two-dimensional array of spots 104.

[0049] The individual intensities of the spots in the two-dimensional pattern of spots 104 at camera 106 may be analyzed by control circuit system 42 to characterize any refractive error (e.g., astigmatism, myopia, or hyperopia) present in the user's eye 46. In one exemplary arrangement, control circuit 42 fits a Zernike polynomial to the measured intensities of spots 104 and processes the Zernike polynomial to determine the user's eye refractive error (e.g., a diopter value or other eyeglass prescription information specifying optical system settings to correct the user's vision by correcting the refractive error associated with eye 46). Control circuit 42 may then use information about the measured refractive error to adjust the position of display 40 relative to eye 46 and / or adjust one or more adjustable lenses in optical system 20.

[0050] For example, consider a myopic user with astigmatism whose right eye (OD) is prescribed with spherical: -3.00 diopters, cylindrical: -1.50 diopters, axis: 180°. This prescription indicates that the user requires spherical and cylindrical corrections of -3.00 and -1.5 diopters, respectively. The axis value of 180° indicates that the user's astigmatism correction is horizontal. In this scenario, spherical correction can be obtained by adjusting the spacing between the display 40 and the eye 46 using a Z-axis positioner, and cylindrical correction can be obtained by tuning a horizontally oriented adjustable cylindrical lens to produce a cylindrical lens power of -1.5 diopters. The user's right eye refractive error can be independently corrected by the control circuit 42 based on the measured characteristics of the user's right eye.

[0051] The content provided to the user may include distant images (e.g., images of mountains) and may include foreground content (e.g., images of people standing 50 cm from the user). Three-dimensional content may be provided by presenting slightly different images to the left and right eyes of the user using respective displays 40L and 40R.

[0052] Accommodation-fusion mismatch can potentially lead to eye fatigue. To minimize eye fatigue, the device 10 may perform operations that help allow the ciliary muscles used to relax. For example, the control circuit 42 may periodically (e.g., every 20 minutes) present distant content (e.g., content at a viewing distance of at least 20 feet away) to the user, and may instruct the user to view the distant content within a predetermined time period (e.g., 20 seconds). The diopter correction or other optical system settings associated with the device 10 may also be adjusted to help enhance the user's eye comfort. For example, the device 10 may be calibrated during manufacturing so that the control circuit 42 is able to place the display 14 and the optical system 20 in a low eye fatigue configuration during normal operation. When calibrating the device 10, the device 10 may be tested to determine the position of the display 40 corresponding to the virtual image at infinity focus. This calibration information may then be stored in the control circuit 42.

[0053] If the user has perfect vision (no eye correction is needed) and if device 10 is displaying distant content (e.g., content where the user's vision is associated with an object that is infinitely far away from the user), device 10 may adjust optical system 20 so that the additional diopter of device 10 is zero. In this arrangement, the user will be able to comfortably view distant content without eye strain.

[0054] As another example, if the user is nearsighted and typically requires a -1.00 diopter lens to comfortably view distant images, the control circuit 42 may make a -1.00 diopter adjustment when presenting distant images and increasing diopter changes as closer content is presented.

[0055] If desired, in addition to using a Shack-Hartmann sensor or measuring refractive error using a Shack-Hartmann sensor, a Tscherning sensor system or a ray tracking sensor system can also be used to sense eye characteristics.

[0056] exist Fig. 7A and Figure 7B 1 shows a portion of an exemplary Tscherning sensor system (Tscherning aberrometer). In a Tscherning sensor system, collimated light 74 from a light source such as a laser 72 or an LED 73 passes through a mask such as mask 120. Mask 120 has an array of openings, such as a circular array of openings having a grid pattern of rows and columns. The presence of mask 120 converts light 74 into a series of parallel beams aligned with the array of openings in mask 120. As shown in conjunction with Fig. 6A As described, these parallel light beams are coupled into waveguide 84 and directed to eye 46 as light 88. After passing through eye 46 and forming an image on the user's retina, these light beams return to waveguide 94 as light 90 ( Fig. 6A ). Waveguide 94 supplies light 90 as light 91 to lens 122, as shown in FIG. Figure 7B After light 91 passes through lens 122, camera 106 may measure the resulting array of light spots associated with the reflected light beams. Control circuitry 42 may analyze the measurements made by camera 106 to characterize the refractive error of the user's eye (eg, using Zernike polynomials).

[0057] If desired, light source 72, mask 120, and waveguide 84 may be omitted, and the array of light beams that would otherwise pass through mask 120 may instead be generated by presenting an array of spots on display 40. Just before sensing the user's eye, the user's eye may be placed in a relaxed state by forming an image on display 40 and moving the virtual target to infinity (e.g., by slowly increasing the spacing between display 40 and eye 46 until an infinity focus position is reached, and / or by adjusting a lens in system 20). In this type of scenario, the light spots in the array may be passed from display 40 to eye 46 without being routed to eye 46 using waveguide 84. Reflected light 90 (as light 91) may be supplied to camera 106 for analysis by control circuitry 42 (e.g., Zernike polynomial fitting, etc.).

[0058] The ray tracing aberrometer is Fig. 8A and Figure 8B 4. In the ray tracing system, a light beam 74 from a light source such as a laser 72 or an LED 73 is scanned by an electrically controlled beam scanning device such as a scanning mirror 124 (e.g., a mirror or other device controlled by the control circuit 42). The scanned light beam is projected onto the retina of the eye 46 through the waveguide 84, and the intensity of the light 74 is pulsed by the laser 72 or the LED 73. This assembly forms an array of spots on the retina of the eye 46. As each spot is projected onto the eye 46 in turn, the reflected light of that spot (e.g., see Fig. 6A The light 90) is guided to the lens 122 through the waveguide 94 as Figure 8B After passing through lens 122, camera 106 can capture an image of each spot, and control circuit 42 can analyze the captured image data (e.g., using Zernike polynomial fitting).

[0059] If desired, light for a ray tracing sensing system (ray tracing aberrometer) may be generated by forming a pattern on display 40 after relaxing the user's eye 46. For example, a circle (halo) or other pattern may be formed on display 40. Before taking eye measurements, the user's eye 46 may be relaxed by moving a virtual target formed of a circle or other pattern to an infinity focus position. In this type of configuration, light source 72, mask 120, and waveguide 84 may be omitted. During measurement, the circular pattern of light on display 40 is directed onto the user's retina and reflected as reflected light 90. After passing through waveguide 94 in direction 96 and exiting as light 91, camera 106 may capture an image of the circle (possibly with an ellipse) for analysis by control circuitry 42. The magnification of the ellipse may be used to determine the spherical portion of the user's prescription, the major and minor axes of the ellipse may be used to determine the cylindrical portion of the user's prescription, and the axis of the user's prescription may be determined from the angle of the major axis of the ellipse measured with camera 106.

[0060] Exemplary operations involving use of device 10 are described in Fig. 9 Shown in.

[0061] During the operation of block 108, device 10 may be calibrated. For example, a test device may be used to characterize device 10 (or a representative device from a batch of devices being calibrated). During the test, display 40 may create a test image while control circuitry 42 directs a positioner in device 10 to position display 40 at its infinity focus position and directs the lenses in lens system 20 to tune to their infinity focus positions. While the image is displayed, an image sensor (e.g., a prosthetic eye) or other test sensor may be placed at the location of a user's eye. Display position offsets and / or lens adjustment offsets that may be required to focus a virtual image at infinity onto the test sensor may then be determined and stored in device 10 to calibrate device 10 for future use by the user.

[0062] During user operation at block 110, device 10 may be adjusted (automatically and / or manually) so that lens 20 and display 40 are in an appropriate position relative to the user's eyes and face (e.g., so that lens 20 and display 40 are separated by an appropriate distance to match the user's interpupillary distance, so that lens 20 and display 40 have an appropriate Y position, etc.). After these initial adjustments are performed, device 10 may measure characteristics of the user's eyes (e.g., to automatically measure the refractive error of the user's eyes to determine the eye prescription for both the user's left and right eyes) using an eye sensing system (e.g., an aberrometer such as a Hartmann-Shack, Tscherning, or ray-tracing sensor or other suitable refractive error measurement device). If desired, the user may manually supply information about the user's prescription to control circuitry 42 using an input-output device. For example, the user may be prompted to supply prescription values ​​(sphere, cylinder, axis) using a touch screen, keypad, voice input, etc.

[0063] During operation of block 112, control circuitry may adjust the position of display 40 (e.g., the spacing of dimension Z of the left display from the user's left eye and the spacing of dimension Z of the right display from the user's right eye), and / or may adjust adjustable lenses in optical system 10 to focus content on display 40 for the user while correcting astigmatism, hyperopia, myopia, and other refractive errors in the user's vision. Focus may be adjusted based on the nature of the content being displayed (e.g., based on whether the content is distant content (such as mountains in a landscape) or close-up content (such as people nearby)) to minimize accommodation-fusion mismatch while taking into account user preferences and user refractive errors.

[0064] After adjusting the focus at block 112, control circuitry 42 may use display system 40 to display images for the user. While displaying the images, control circuitry 42 may determine whether any content is associated with distant objects (distant virtual objects, such as distant computer-generated mountains in a landscape), or with the user's relaxed eye focus state (eyes focused at infinity). A timer may be maintained to track the amount of time that elapses between time periods in which distant (e.g., infinity focus) content is displayed for more than a predetermined amount of time (e.g., at least 20 seconds, at least 10 seconds, a threshold time of less than 2 minutes, etc.).

[0065] When the timer expires (e.g., after a period of at least 15 minutes, at least 20 minutes, 10 to 30 minutes, less than 40 minutes, or other suitable time limit that does not allow the user to continue without relaxing the eyes), the control circuit 42 can conclude that it is time for the user to relax the eyes. Therefore, content at a long distance (e.g., infinity or greater than 20 feet away) can be presented to the user (block 116). As the user views the distant content (and as the control circuit 42 adjusts the position of the display 40 and the optical system 20 to their corresponding infinity focus states), the ciliary muscles in the user's eye 46 relax. After an appropriate eye relaxation time has passed (e.g., a period of at least 10 seconds, at least 20 seconds, at least 30 seconds, at least 15 to 30 seconds, less than 3 minutes, or other suitable relaxation time period), the process can return to block 112, as shown by line 118. Eye relaxation content (long distance) displayed during the operation of block 116 may include a message such as "Relax your eyes" presented at an infinity focus point or other suitable large distance, or may include embedded content (e.g., mountains at infinity focus or other suitable large distance) that is pressed into content that would otherwise be presented to the user. For example, a user playing a video game may be in a confined space and close to surrounding objects. To relax the user's eyes during the operation of block 116, a distant mountain view may be inserted into the video game, thereby avoiding the need to interrupt the user with a text message ("Relax your eyes") or other content that may interrupt the user's interest in the video game.

[0066] The user of device 10 may not have perfect vision. For example, the user may be nearsighted, may be farsighted, and / or may have astigmatism. To correct for imperfect vision, a vision correction lens may be coupled to device 10. For example, lens 20 may have a fixed portion and a removable vision correction portion.

[0067] For example, the vision correction lens may have positive power (to correct for hyperopia) or negative power (to correct for myopia). Astigmatism may also be corrected. Corrective lenses that correct for astigmatism are not rotationally symmetric. To ensure that a non-rotationally symmetric vision correction lens is properly oriented, device 10 may have a vision correction lens orientation feature (e.g., a magnetic correction structure or a mechanical coupling structure that accurately aligns the corrective lens when coupling the corrective lens to lens 20L or 20R in device 10, so that when the user wears device 10, the corrective lens has an ideal angular orientation relative to device 10 and display 40, and therefore to the user's eye).

[0068] exist Fig.10 An exemplary vision correction lens arrangement is shown in FIG. Fig.10In the example of FIG. 1 , vision correction lens 130 has been mounted in device 10 overlapping lens 20. Lens 20 may be a catadioptric lens or other suitable lens. Lens 20 may be tunable or may be fixed. Lens 130 may be rotationally symmetric or may be rotationally asymmetric. Fig.10 As shown, lens 130 may have a convex outer surface SF3 facing lens 20, and may have a concave inner surface. In a configuration where lens 130 is not rotationally symmetric to compensate for astigmatism, the concave inner surface of lens 130 may be characterized by a first curvature (shown by cross-sectional profile SF1) along a first dimension (e.g., along the X-axis), and may be characterized by a different second curvature (shown by cross-sectional profile SF2) along a second dimension (e.g., along the Y-axis). When lens 130 overlaps lens 20, a two-part lens is formed and corrected to compensate for the user's vision problems.

[0069] Vision correction lens 130 may have a support structure such as vision correction lens mounting ring 132. Lens 20 may be mounted in a support structure such as lens mounting structure 134 (e.g., a portion of a housing or other structural support in device 10). Structure 134 may have an opening (e.g., a circular opening or other suitably shaped opening) that receives mounting ring 132. When ring 132 is received within structure 134, alignment features associated with ring 132 and structure 134 precisely align vision correction ring 130 relative to structure 134 (e.g., determining the angular orientation of ring 132, and therefore vision correction lens 130, relative to lens 20, display 40, and other portions of device 10 to be less than 2°, less than 4°, or other suitable amount).

[0070] By way of an exemplary configuration, a magnetic alignment structure may be used on the ring 132 and the structure 134. Fig.11 As shown, for example, lens 130 may be mounted within ring 132, and when ring 132 is rotated within the circular opening of support structure 134, the lens may rotate relative to center point CP. In order to achieve the desired rotational alignment of vision correction lens 130 relative to structure 134 and the rest of device 10, ring 132 may be provided with one or more magnets, such as magnets 138 and 140, and structure 134 may be provided with one or more corresponding magnets 136 and 142. When vision correction lens 130 is mounted to device 10, the magnetic attraction between magnets 138 and 136 and the magnetic attraction between magnets 140 and 142 will help to align and maintain lens 130 in the desired angular orientation within device 10, thereby ensuring that lens 130 satisfactorily corrects the user's astigmatism.

[0071] If desired, the vision correction lens 130 may be a Fresnel lens, such as Fig.12As shown. Fresnel vision correction lens 130 (e.g., Fig.12 The lens 130) may be a spherical lens (eg, a rotationally symmetric lens), such as Fig.13 , or may be a cylindrical lens (e.g., a cylindrical lens without spherical power or a hybrid cylindrical-spherical lens), as shown in FIG. Fig.14 A front view of the rotationally asymmetric lens 130 is shown.

[0072] To ensure that the user's vision can be satisfactorily corrected when using device 10, vision correction lens 130 can be coupled to device 10 in alignment with lens 20 before using device 10. For example, a left vision correction lens can be coupled to device 10 in alignment with (overlapping) left lens 20L, and a right vision correction lens can be coupled to device 10 in alignment with right lens 20R. Vision correction lens 130 can be coupled to device 10 magnetically (e.g., using magnets and / or magnetic materials) using a threaded retaining ring, using a clamp, using an adhesive, and / or using other suitable mounting structures. In some configurations, vision correction lens 130 can be removably coupled to device 10 (e.g., so that a different user can replace vision correction lens 130 with another set of vision correction lenses if desired).

[0073] When vision correction lens 130 is incorporated into device 10, lenses 130 and 20 operate together. For example, lens 20 can be used to provide the majority of the diopter used to focus display 40, while lens 130 can correct for user-specific vision problems such as astigmatism, etc. If desired, an adjustable lens structure can be used in combination with vision correction lens 130 and / or other fixed lenses (e.g., catadioptric lenses, Fresnel lenses, etc.).

[0074] According to one embodiment, a head-mounted device is provided, the head-mounted device being configured to generate an image viewable by a user having an eye refractive error, the user's eye being located at an eye position, the head-mounted device comprising: a display configured to display the image; a lens through which the image is viewable; a sensor; a locator coupled to the display; and a control circuit configured to measure the refractive error using the sensor and to adjust the locator based on the measured refractive error.

[0075] According to another embodiment, the sensor comprises at least one waveguide.

[0076] According to another embodiment, the sensor includes an input coupler that couples light into the waveguide, and includes an output coupler that couples light out of the waveguide.

[0077] According to another embodiment, the output coupler is configured to allow the image to pass from the display to the eye position.

[0078] According to another embodiment, the input coupler and the output coupler are volume holograms.

[0079] According to another embodiment, the sensor further comprises a camera that measures light from the output coupler.

[0080] According to another embodiment, the head-mounted device also includes a light source selected from the group consisting of: a laser; and a light emitting diode that supplies light; an additional waveguide having an additional input coupler and an additional output coupler, the additional input coupler coupling the light into the additional waveguide, and the additional output coupler directing the light out of the additional waveguide toward the eye position.

[0081] According to another embodiment, the head-mounted device also includes a lens array inserted between the output coupler and the camera, wherein the control circuit is configured to measure the refractive error by analyzing the light spot generated by the lens array at the camera.

[0082] According to another embodiment, the sensor is configured to form a Shack-Hartmann aberrometer.

[0083] According to another embodiment, the sensor is configured to form a Tscherning aberrometer and the control circuit is configured to measure the refractive error by analyzing a light spot at the camera generated when the array of dots is displayed on the display.

[0084] According to another embodiment, the sensor is configured to form a ray tracing aberrometer and the control circuit is configured to measure the refractive error by analyzing a light pattern at the camera generated when the shape is displayed on the display.

[0085] According to another embodiment, the shape comprises a circle.

[0086] According to another embodiment, the control circuit is configured to allow the eye to relax by periodically presenting content on the display while adjusting at least one selected from the display and the lens to an infinity focus setting.

[0087] According to another embodiment, the head mounted device further includes an input-output device, and the control circuit is configured to receive user input regarding the refractive error using the input-output device.

[0088] According to another embodiment, the user input includes an eyeglass prescription, and the control circuit is configured to adjust the position of the display with the positioner based on the eyeglass prescription.

[0089] According to another embodiment, the lens includes an adjustable lens, and the control circuit is configured to adjust the adjustable lens based at least in part on the measured refractive error.

[0090] According to another embodiment, the tunable lens includes at least one tunable liquid crystal cylindrical lens, the measured refractive error is associated with astigmatism of the eye, and the control circuit is configured to adjust the tunable liquid crystal cylindrical lens to correct the astigmatism based on the measured refractive error.

[0091] According to another embodiment, the lens comprises a vision correction lens.

[0092] According to another embodiment, the vision correction lens is non-rotationally symmetric and is configured to compensate for astigmatism.

[0093] According to another embodiment, the vision correction lens is a Fresnel lens.

[0094] According to another embodiment, the lens includes a fixed lens and a removable vision correction lens configured to overlap the fixed lens.

[0095] According to another embodiment, the removable vision correction lens includes a rotational alignment structure configured to rotationally align the removable vision correction lens relative to the fixed lens.

[0096] According to another embodiment, the rotational alignment structure comprises a magnet.

[0097] According to one embodiment, a head-mounted device is provided, comprising: a display configured to display an image; a lens; a sensor comprising at least one hologram; and a control circuit configured to measure refractive error in an eye using the sensor and to adjust at least one of the positions of the lens and the display based on the measured refractive error.

[0098] According to another embodiment, the sensor includes a camera, the refractive error includes astigmatism, and the lens includes an adjustable liquid crystal cylindrical lens, and the control circuit is configured to adjust the adjustable liquid crystal cylindrical lens to correct the astigmatism when viewing the display.

[0099] According to one embodiment, a head-mounted device is provided, comprising: a display; a lens through which the display can be viewed from an eye position; a waveguide; a hologram on the waveguide through which the display can be viewed from an eye position; a camera; and a control circuit configured to measure a refractive error of the eye based on measurements of light leaving the waveguide by the camera.

[0100] The foregoing is merely illustrative and various modifications may be made to the embodiments described. The foregoing embodiments may be implemented independently or in any combination.

Claims

1. A head mounted device, comprising: shell; a display in the housing, wherein the display includes an array of pixels configured to provide a display image; and A fixed lens is coupled to the housing and overlaps the pixel array, wherein the housing is configured to receive a removable lens, and wherein the display image is viewable through the fixed lens and the removable lens when the removable lens is received by the housing.

2. The head mounted device according to claim 1, wherein: The removable lens is received at a position overlapping the fixed lens and overlapping the pixel array.

3. A head-mounted device according to claim 1, wherein the housing includes a support structure, the support structure is configured to receive a corresponding mounting structure of the removable lens, and wherein the mounting structure of the removable lens overlaps with the support structure when received by the support structure.

4. The head mounted device according to claim 3, wherein: The mounting structure of the removable lens includes a mounting ring surrounding a lens element of the removable lens.

5. The head-mounted device according to claim 4, wherein the support structure of the housing has an opening, and the fixed lens is arranged in the opening.

6. A head-mounted device according to claim 5, wherein when the removable lens is received by the support structure, the lens element overlaps the opening.

7. The head mounted device according to claim 3, further comprising: An alignment structure on the support structure is configured to rotationally align the removable lens relative to the support structure.

8. The head mounted device according to claim 7, wherein: The alignment structure on the support structure is configured to couple to corresponding alignment structure on the removable lens to maintain the removable lens in a specific rotational alignment relative to the support structure.

9. The head mounted device of claim 1, wherein the removable lens comprises a removable vision correction lens.

10. The head mounted device of claim 1, wherein the removable lens comprises a spherical lens.

11. The head mounted device of claim 1, wherein the removable lens comprises a cylindrical lens.

12. The head mounted device of claim 1, wherein the display is a left display, wherein the fixed lens is a left fixed lens, wherein the removable lens is a left removable lens, and wherein the head mounted device further comprises: Right monitor; and a right fixed lens, wherein the housing is configured to receive a right removable lens, and wherein the right display is viewable through the right fixed lens and the right removable lens when the right removable lens is received by the housing.

13. A head mounted device comprising: shell; a first display coupled to the housing and having a first array of pixels; a first lens coupled to the housing and overlapping the first pixel array; a second display coupled to the housing and having a second array of pixels; and a second lens coupled to the housing and overlapping the second pixel array, wherein the housing includes a support structure configured to receive a third lens at a position overlapping the first lens and the first pixel array and to receive a fourth lens at a position overlapping the second lens and the second pixel array.

14. The head mounted device of claim 13, wherein the first lens and the second lens are fixed within the housing, and wherein the third lens and the fourth lens are removable from the support structure of the housing.

15. The head mounted device of claim 13, wherein: The support structure provides a first opening and a second opening, wherein the position of the third lens overlaps with the first opening, and wherein the position of the fourth lens overlaps with the second opening.

16. The head mounted device of claim 15, wherein the first lens is disposed within the first opening, and wherein the second lens is disposed within the second opening.

17. A head mounted device comprising: shell; a display coupled to the housing, wherein the display includes an array of pixels; a fixed lens coupled to the housing and overlapping the pixel array; and An additional lens is removably coupled to the housing and overlaps the fixed lens and the pixel array.

18. The head mounted device of claim 17, wherein the housing includes a lens mounting structure, and a corresponding mounting structure of the additional lens is removably coupled to the lens mounting structure.

19. A head-mounted device according to claim 18, wherein the mounting structure of the additional lens includes a mounting ring surrounding the lens element of the removable lens.

20. The head mounted device of claim 19, wherein the lens mounting structure of the housing has an opening, the fixed lens is disposed in the opening, and wherein the lens element overlaps the opening of the lens mounting structure.

Images