Eyewear display system for displaying virtual images within the user's field of view using invisible micromirror elements

Abstract

To provide an eyewear display system that offers improved immersion, minimizes weight in particular, has the largest possible substantially complementary field of view, and has the ability to address issues such as convergence-accommodation conflict and / or vision correction problems. [Solution] An eyewear display system for displaying a virtual image within the user's field of view, comprising: a display unit for emitting light rays as computer-generated image information in a radial direction; and a deflection unit for deflecting light rays toward the user's eyes, wherein at least one micromirror element is tilted within a carrier structure and each has a reflective surface for deflecting light rays emitted by the display unit as computer-generated image information, the system comprising at least one micromirror element and the carrier structure arranged within a sealed housing element of the deflection unit filled with liquid to provide an eyewear display system that provides improved immersion.

Description

Technical Field

[0001] This application claims priority to International Application No. PCT / IB2024 / 062381, filed on December 9, 2024, the entire disclosure of which is incorporated herein by reference.

[0002] The present disclosure relates to an eyewear display system for displaying a virtual image within a user's field of view, comprising a display unit for emitting light rays in a light emission direction as computer-generated image information, and a deflection unit for deflecting the light rays emitted by the display unit as computer-generated image information towards the user's eyes, wherein at least one micromirror element can be tilted within a carrier structure and each has at least one reflecting surface for deflecting the light rays emitted by the display unit as computer-generated image information.

Background Art

[0003] An eyewear display system for displaying a virtual image within a user's field of view, known as "augmented reality glasses" or simply "AR glasses", can superimpose virtual objects in the form of virtual images onto the user's field of view of the natural environment, thereby virtually complementing the field of view. By displaying stereoscopic images, these virtual objects can be freely placed within the space. For this reason, it is advantageous to enable a display with as wide a virtually complementable field of view and high (angular) resolution as possible in order to create a sense of immersion through the permanent visibility and spatially consistent positioning of the virtual objects, i.e., the feeling as if the virtual objects were physical objects. The weight of such glasses is also a factor affecting the sense of immersion and can contribute to an unnatural feeling for the user, especially when moving the head. The so-called problem of vergence adjustment conflict is also a well-known effect that impairs immersion, i.e., immersion.

[0004] The convergence-accommodation discrepancy problem exists in all 3D displays that use two stereo images to display 3D objects. The 3D information, i.e., the distance from the eye to the object, is given by the shifted stereo images. This distance differs from the distance at which the eye focuses to see a sharp image. A similar problem arises in AR applications when virtual 3D objects are integrated into a real 3D environment. If the focal length of the stereo images does not match the focal length of the real environment, it is not possible to see both the real and virtual scenes simultaneously, even if they are displayed in the same location within the environment.

[0005] Prior art has shown various optical methods for mirroring virtual images within the field of view of a natural environment. However, making the necessary optical systems small enough to achieve the form factor and weight factor of ordinary eyeglasses remains a technically unresolved problem. Eyeglasses that are too large impose technical limitations on possible applications, for example, because people will not accept wearing a large product on their face in everyday situations. If the eyeglasses are too heavy, AR glasses can only be worn for a limited time. Examples of possible solutions are described in German Patent DE 10 2020 206 392 A1 and German Patent DE 10 2023 101 777 A1.

[0006] U.S. Patent No. US 10 623 707 B2 describes augmented reality (AR) glasses that project a high-resolution image onto the central field of view (fovea) and a lower-resolution image area onto the peripheral field of view. To achieve this, the direction of gaze is measured using eye-tracking sensor technology, and the projection optics are adjusted accordingly.

[0007] U.S. Patent Applications US 2020 0186761 A1 and U.S. Patent Applications US 11 422 274 B2 present a method that allows the focal length of an AR optical system to be adjusted to display objects at different distances. This reveals a technical solution to the convergence-accommodation inconsistency problem. U.S. Patent Application US 2020 0186761 A1 also includes an eye-tracking module that measures convergence-divergence eye parameters. In addition, it is proposed to use these measurements to track the optical system to the eye in order to enable eye-tracking for different eye positions.

[0008] Therefore, the technical challenge is to provide an eyewear display system that offers improved immersion, minimizes weight in particular, has the largest possible substantially complementary field of view, and is also capable of addressing typical problems with AR glasses, such as convergence-accommodation inconsistencies and / or vision correction issues. [Prior art documents] [Patent Documents]

[0009] [Patent Document 1] German Patent No. DE 10 2020 206 392 A1 [Patent Document 2] German Patent No. DE 10 2023 101 777 A1 [Patent Document 3] United States Patent No. US 10 623 707 B2 [Patent Document 4] U.S. Patent Application Publication No. US 2020 0186761 A1 [Patent Document 5] United States Patent No. US 11 422 274 B2 [Overview of the project] [Problems that the invention aims to solve]

[0010] This problem is solved by the subject matter of the independent claim. Favorable implementation forms are evident from the dependent claims, description, and figures. [Means for solving the problem]

[0011] One embodiment relates to an eyewear display system for displaying a virtual image within a user's field of view, comprising a display unit for emitting light as computer-generated image information in an emission direction, and a deflection unit for deflecting the light emitted by the display unit towards the user's eyes as computer-generated image information. The emission direction is preferably at least substantially toward the user's field of view (forward, so that the light is emitted into the field of view), and the deflection unit is configured to be positioned at least within the user's field of view (in front of one or both of the user's eyes) together with at least one micromirror element as described below, and is used to deflect the light back towards one or both of the user's eyes.

[0012] The deflection unit has at least one micromirror element, i.e., one or more, in particular, a plurality of tiltable micromirror elements, each of which is configured to be arranged within a carrier structure, and each of which has a reflective surface for deflecting light emitted by the display unit towards the user's eyes as computer-generated image information. The reflective surface transmits ambient light emitted from the environment in front of the user within the user's field of view toward the eyes. The reflective surface can therefore be considered a semi-transparent mirror surface. Thus, a micromirror element can also have multiple mirror surfaces. This is the case, for example, when each of the one or more micromirror elements has a coated substrate, in particular a glass substrate. For example, one side of the substrate may be coated and the opposite side of the substrate may not be coated. Thus, two reflections may then occur, in which case one side shall be one reflective surface and the opposite side shall be the other reflective surface.

[0013] The reflection of a coated surface can be (technically) tuned in a desired manner using a suitable coating (designed to produce a desired optical effect), while the reflection of an uncoated surface is based on Fresnel reflection resulting from changes in the refractive index of the substrate and the environment (e.g., the liquid in the housing element described below). In the case of one or more micromirror elements stored in a liquid, the reflectivity of the latter is generally very low, as the refractive indices of the typical glass and liquid used as the substrate are very similar. Alternatively, the opposite side of the substrate may also have a coating. For example, this may be a counterforce coating, which, in contrast to a coating designed to produce an optical effect, is designed to compensate for stresses that occur between the substrate and the coating on one side, which could lead to warping of the substrate. The technically tuned reflective surface may be located within the volume of the micromirror element, and a total of three reflective surfaces may be present. In this case, there are two additional reflections at the interface between the micromirror element and the environment (ideally the liquid). The additional reflections may be of a dependent nature, i.e., significantly weaker than the (primary) reflection on the technically tuned reflective surface. For example, additional reflections may be one or more orders of magnitude weaker than the primary reflection. It is also possible to coat one side and the opposing side with a coating designed to achieve the desired optical effect. This allows, for example, the (primary) reflections on the front and back of the substrate to be technically tuned, i.e., the optical properties to be tuned. Multiple coatings can be applied to one side of the substrate, and one or more micromirror elements may each have multiple reflective surfaces.

[0014] Multiple micromirrors can be understood to mean, for example, at least two, at least twenty, at least 100, or at least 1000 micromirrors. As is typical with micromirrors, the reflective surface is small, for example, <100mm. 2or <20mm. One or more micromirrors are movably mounted within the carrier structure so that the reflective surfaces can be aligned in two dimensions by angular alignment. This allows the light emitted by the display unit, i.e., the light from the display unit, to be deflected towards the eye or pupil for different orientations and / or positions of the eye. The deflection unit is configured to be positioned at least partially (i.e., partially or completely), particularly with one or more micromirror elements, in the optical path of ambient light from the user's field of view to the user's eye so that the virtual image corresponding to the computer-generated image information can be superimposed on actual objects in the environment within the user's field of view, because one or more micromirror elements (as required for AR glasses) transmit at least partially the light from the environment (ambient light). To obtain a better sense of immersion with the largest possible artifact-free virtual image, the deflection unit and / or display unit are controlled according to the orientation of one or both eyes, for example, using a control unit as described below.

[0015] Advantageously, all or at least most (preferably almost all) of one or more micromirror elements are aligned with their angular alignment such that, at least in the standard operating mode of the eyewear display system, only light from the display unit is directed towards the user's eyes. In the standard operating mode, this angular alignment may be provided regardless of whether the micromirror elements are illuminated by the display unit. This has the advantage that other light sources do not cause visible reflections in the eye. This prevents annoying light reflections that appear as ghost images. This is particularly advantageous for outdoor applications where the sun, as a very bright light source, could otherwise cause unpleasant light reflections. A further advantage resulting from this is that high reflectivity, such as a semi-transparent coating, can be selected for the reflective surfaces of one or more micromirror elements, because even with high reflectivity, undesirable light reflections in the eye cannot be amplified.

[0016] In addition, a power-saving operating mode may be provided for the glasses display system, in which micromirror elements (in particular, only) that are not illuminated by the display unit are moved to or aligned to a predetermined stationary position. In the stationary position, the actuator system having the actuator elements described below may be completely or partially deactivated. For example, one or more micromirror elements may be moved to the stationary position when no virtual image is displayed or when the virtual image has a large / long black area. Preferably, one or more micromirror elements are moved again only when illuminated by the display unit. The stationary position of one or more micromirror elements may be specified to correspond to the stationary position of each eye. In the stationary alignment of one or more micromirror elements, the light from the display unit is directed essentially only to the user's eye when the eye is in its stationary position. However, in this case, the reflection conditions are not met and interference reflections may occur due to light coupled from behind. Undesirable reflections from ambient light can cause visual artifacts under some circumstances, but it has been shown that people mostly keep their eyes in the aforementioned stationary position or neutral gaze position, minimizing the possibility of artifacts occurring. Overall, it is therefore advantageous to select a stationary alignment of one or more micromirror elements depending on the stationary position of the eye, so that the reflection conditions at the projector's output port are met for most of the time, even when the actuator is switched off.

[0017] Alternatively, or in addition, a high-quality operating mode may be provided in which the angular alignment of one or more micromirror elements is continuously adjusted, i.e., one or more micromirror elements are always tracked in accordance with eye movements (e.g., even when a virtual image is not displayed or when there are large / long black areas in the virtual image). It may also be specified that the eyewear display system has a sensor device (e.g., a camera sensor device) that detects and / or evaluates the environment, for example with respect to general lighting conditions, and an automatic switching device designed to automatically switch between different operating modes based on one or more predetermined switching criteria. One switching criterion could be, for example, the probability of occurrence of bright light spots (which can easily cause distracting reflections) evaluated by the sensor device, with the power-saving mode activated when this probability is low and the high-quality operating mode activated when this probability is high. The environment may also be recorded and analyzed with respect to location data, for example, when using the eyewear display system outdoors, bright light spots are more likely to occur than indoors. Power consumption and immersion can be optimized by specifying appropriate control schemes.

[0018] The display unit may have one or more preferably flat screens or display elements ("displays") for generating light, but may also have one or more (laser) projector elements. In particular, the display unit can be a stereo display unit suitable for generating a virtual stereo image within the field of view. For this purpose, the stereo display unit may have two screen elements or two (laser) projector elements, each element assigned to one of the user's eyes. For example, the screen elements or (laser) projector elements may each be arranged and configured on the temple unit of the glasses display system on the user's side. Where possible, light from the light-generating pixel elements of the display unit should strike only one micromirror element and not be seen simultaneously through one or more adjacent micromirror elements. In the latter case, adjacent micromirror elements are generally tilted at a non-zero angle to each other, i.e., they are given different alignments, so that the same pixel information will be perceived in two different spatial directions, i.e., as two different virtual pixels (image points of a virtual image).

[0019] In one embodiment, the display unit may include a light-emitting display, in particular a so-called "microdisplay," and further a microlens array, a so-called "microlens array." The microlens array has a plurality of microlens elements arranged in parallel (as opposed to a series arrangement) in the beam path from the light-generating display of the display unit to the output hole of the display unit. Such microlens elements may have a diameter of, for example, less than 1000 μm, preferably less than 500 μm, and / or greater than 50 μm. Preferably, the display unit also has a projector optical system (particularly for chromatic aberration correction) having a plurality of optical lenses. The projector optical system is arranged in the beam path between the microlens array and the output hole. In particular, the projector optical system is designed to guide light from just one microlens element of the microlens array to a corresponding micromirror element. Thus, exactly one micromirror element may be assigned to each microlens element used during the operation of the eyewear display system. The optical imaging achieved by the projector optics therefore ensures that the light emitted from the microlens elements is visible or perceptible only through exactly one micromirror. This has the advantage that multiplexing is not required (or only a small amount is required when using the adjustable aperture unit described below), meaning that all (or many, when using the adjustable aperture unit) of one or more micromirror elements can simultaneously display virtual pixels. In contrast to the multiplexing approach, a lower light intensity of the light-generating pixel elements is therefore sufficient, because the pixel elements can be switched on / operated for the entire duration of a single frame, not just for a (very short) portion of a single frame. Therefore, low-brightness display technologies such as organic light-emitting diodes (OLEDs) can also be used.

[0020] When the projector optical system is corrected for chromatic aberration, the associated optical image is also corrected for chromatic aberration, and thus each image from the microlens element to the micromirror element for the primary colors of the display unit is at least essentially wavelength independent. The primary colors are typically red, green, and blue. The purpose is to technically ensure that the resulting field of view for each micromirror element is limited to only one microlens element, thereby preventing crosstalk in the image content.

[0021] Preferably, for each microlens element, its own pixel element area on the light - generating display is assigned. The light from the light - generating pixel elements of this pixel element area is imaged only through one microlens element. The microlens element and the projector optical system can be adapted to each other such that, in addition to imaging the plane of the microlens element onto the plane of one or more micromirror elements, a sharp image of the light - generating pixel elements is also projected onto an "eye box" associated with the user's eye or the position of the eye. The plane can also be a curved plane or other two - dimensional manifold in three - dimensional space. Preferably, the aforementioned adjustment is performed under boundary conditions where the maximum image sharpness of the virtual image is achieved when the eye is focused on the center of each micromirror element. In this alignment, the eye sees each micromirror element with maximum imaging performance. Since the imaging performance of the eye rapidly and sharply decreases towards the side, the resulting decrease in imaging for the micromirror elements towards the side of the central line of sight is not a problem. When the display unit is arranged within or on the template of the glasses display system, the plane of the microlens element and the plane of one or more micromirror elements are inclined with respect to each other. Thus, a shine - proof optical system can be selected for the projector optical system. In principle, however, the optical system can be adapted to an alternative geometric arrangement of the display unit with respect to the deflection unit.

[0022] In a further embodiment, the microlens array is configured to be moved, and in particular shifted, relative to the photogenerating display by a focus actuator. This is particularly advantageous because the focal length of the microlens array is relatively short, for example, less than 2 mm, preferably less than 1 mm. As a result, only small amounts of mobility / displacement, for example less than 2 mm, preferably less than 1 mm, are required to improve the virtual image in terms of improved focusing. For example, the focal plane can be quickly shifted when the user's eye jumps from one virtual object to another. This can mitigate the convergence-accommodation contradiction problem and, consequently, improve immersion.

[0023] In another embodiment, not all micromirror elements are assigned to microlens elements. Therefore, there may be more micromirror elements than microlens elements. Thus, micromirror elements not assigned to microlens elements are then imaged directly onto the photogenerating display via the projector optics, or the corresponding pixel element area of ​​the photogenerating display is imaged onto the micromirror elements not assigned to microlens elements. Preferably, micromirror elements not assigned to microlens elements are positioned closer to the outer edge of the field of view, i.e., closer to each adjacent temple of the eyeglass display system, than one or more micromirror elements assigned to microlens elements. This is advantageous because in the nose region of the field of view, the angular distance from one micromirror element to the next micromirror element is typically reduced, which increases the risk of unwanted crosstalk from one micromirror element to the next adjacent micromirror element. This is because the distance between the micromirror elements and the display unit is significantly larger in the temple region than in the bridge region. The angular distance is determined by the difference in the inclination angles of adjacent micromirror elements.

[0024] In a further embodiment, the microlens array is designed to correct and / or compensate for the dispersion of light emitted by the light-generating display. This can be achieved, for example, using additional diffractive structures as part of the microlens array and / or using (outer) boundary surfaces (also referred to as interfaces) that are inclined with respect to each other. Such mutually inclined boundary surfaces can compensate for dispersion in a manner similar to the prism effect. This improves the image quality and results in an improvement in immersion.

[0025] In one embodiment, one or more micromirror elements and support structures can be arranged and configured within a sealed housing element of a deflection unit filled with a liquid. The housing element can be arranged and configured in front of the user's eye, similar to a conventional glasses lens. Thus, the liquid and one or more micromirror elements and support structures are arranged and configured within the interior space of the housing element such that the one or more micromirror elements and support structures are surrounded by the liquid. The housing element is impermeable to oil and / or water and is made of or uses a material that is at least substantially transparent to ambient light and light from the display unit, similar to the case of a conventional glasses lens. The one or more micromirror elements and support structures are also, preferably, made of a transparent material, as will be described again below.

[0026] The liquid bath of micromirror elements and support structures has a damping effect, suppressing vibrations and preventing undesirable small abrupt changes in the angular alignment of the reflective surface. This is advantageous because the eye performs abrupt movements of up to 1000° per second and then comes to a stop. In addition, the liquid reduces material transitions, i.e., the difference in refractive index at the interface between the liquid and the micromirror or support structure. This reduces Fresnel reflection on the one hand and other refractive effects on the other. The reduction of both reflection and effect reduces the visibility of elements or structures in the liquid bath, as is known from, for example, glass components immersed in water. This prevents in-field artifacts that detract from the user's immersive experience and allows the use of micromirror element placement configurations in which more micromirror elements ("micromirror arrays") are placed directly in the field of view in front of the user's eyes. However, micromirror arrays enable virtual interpolation over a wide area of ​​the field of view with greater (angular) resolution for the virtual image and are therefore a prerequisite for immersive glasses display systems with dimensions similar to commercially available glasses.

[0027] In a further embodiment, one or more mirror elements and / or support structures and / or other components surrounded by or adjacent to the liquid (such as the inner-facing sides of the housing element) are specified to be (at least substantially) transparent, as described above for the housing element. The micromirror elements and / or support structures and / or other components are made from or using transparent materials having a first refractive index. In particular, the housing element and / or one or more micromirror elements and / or support structures and / or other components may be made from the same material, which facilitates the matching of their optical properties with one another.

[0028] The liquid is also transparent (at least essentially) to ambient light and has a second refractive index that is tuned to match the first refractive index with respect to the smallest possible deviation. In particular, the second refractive index (preferably at a defined temperature value within the temperature range specified below) can be equal to the first refractive index for at least one wavelength within the green wavelength range. Thus, the liquid should be selected so that the second refractive index does not deviate by a specified limit value, for example, 0.005, over a specified wavelength range, for example, 400 nm to 700 nm and / or a specified temperature range, for example, 0° to 30°. The liquid can also be optimized for one or more subranges of each range, for example, having a second refractive index that is particularly similar to the first refractive index in a wavelength range of 540 nm ± 30 nm and / or a temperature range of 21° ± 2°. The similarity in the green wavelength range (520 nm to 565 nm) is particularly advantageous because artifacts in the green wavelength range have been shown to be perceived by humans with higher resolution than in the red or blue wavelength ranges. In this subrange, particularly in the green wavelength range, a smaller maximum limit value for this deviation, e.g., 0.002, may be specified. Preferably, the refractive index curves of the liquid and the first material plotted over this wavelength range intersect within the green wavelength range. Such liquids are known as "refractive index matching liquids," and those with the desired properties are commercially available. It may therefore be advantageous to actively control the temperature of one or more micromirror elements, i.e., measure it and set a target temperature or target temperature range by heating or cooling. Thus, a temperature control device for the liquid may be provided. The temperature control device may comprise a sensor unit for measuring the temperature of the liquid and a temperature control unit for adjusting the temperature of the liquid to a predetermined temperature value, i.e., according to the measured value and the predetermined temperature, for either heating or cooling. In this way, temperature-dependent deviations can be avoided or at least reduced.

[0029] This means that because ambient light is refracted very little as it passes through the deflection unit, any changes in ambient light remain at least within the wavelength range of the ambient light and / or at least within the angular range of the ambient light and / or at least below the user's perceptual threshold of temperature. As a result, the material transitions, and therefore one or more micromirror elements and / or carrier structures and / or other components surrounded by the liquid are substantially invisible to the user. This means that one or more micromirror elements can be positioned and configured over a wide area in front of the user's eyes without interfering with the user's perception of the environment and therefore the virtual image, significantly improving the sense of immersion when using the eyewear display system.

[0030] In another embodiment, one or more micromirror elements are mechanically coupled to a common actuator element, particularly using a two-dimensional guide matrix structure. The guide matrix structure may be mechanically scanned by a carrier structure to achieve individual tilts (angular alignments) of one or more micromirror elements. Alternatively, it may be specified that one or more micromirror elements are each coupled to a separate actuator element. In both cases, the angular alignment of one or more micromirror elements may be controlled via a common or individual actuator element according to stored specifications, once in the form of a mechanical guide mechanism and once, for example, in the form of a lookup table. The common or individual actuator elements may be designed to move at least some of the one or more micromirror elements, particularly most and / or all of the one or more micromirror elements, differently from each other and / or nonlinearly. Thus, the angular alignment of the reflective surfaces may be specified individually and / or nonlinearly, for example, by the guide matrix structure and / or actuator control specifications. This individual and / or nonlinear adjustment ensures that deflected light always reaches the eye and that a larger, coherent virtual image is also formed. Common actuator elements reduce the number of components required for a deflection unit configured to be placed within the user's field of view. This helps to reduce the visibility of structures within the user's field of view, thereby improving immersion.

[0031] One or more micromirror elements can each be equipped with a separate angle sensor to measure their respective angular alignment. This allows the target and actual angular alignment of each reflective surface to be compared, thereby helping to reduce any undesirable virtual pixels in the virtual image. Using such angle sensors, small deviations from the target on the order of 1 / 120° can be compensated (and therefore by software) using corresponding control signals to one or more actuator elements.

[0032] In one embodiment, the reflective surface is a hexagonal reflective surface, and in particular, each micromirror element has a coating on its reflective surface. The reflective surface may have a diameter of at least 1 mm, particularly at least 2 mm, and / or up to 10 mm, particularly up to 4 mm, in particular a total height, and / or width. This hexagonal shape allows for a flat display corresponding to that of a high-resolution virtual image, which also results in a low artifact level without reducing immersion, due to the particularly high density arrangement configuration of the micromirror elements and the reduced visibility of one or more micromirror elements and associated components. When polarization is used for the virtual image, it is advantageous to select a coating with high reflectivity for the polarization used. For example, a reflectivity of 20% may be selected. The reflectivity may deviate by less than 10% (and therefore between 10% and 30%), preferably less than 5% (and therefore between 15% and 25%), over the range of relevant (visible) wavelengths. This is because, when viewing the natural environment through a partially mirrored reflective surface, both polarization states are present in the natural ambient light, thus increasing the effective transparency of one or more micromirror coatings. The coatings also allow for the definition of desired reflective properties without adversely affecting the visibility of one or more micromirror elements, which would otherwise be affected (for example, by the shape of one or more micromirror elements).

[0033] A coating whose reflective properties are matched to the emission spectrum of the display unit, particularly to the maximal values ​​within the emission spectrum, is especially advantageous. Typically, a display unit has several spectral maximal values ​​("peaks"), generally for red, green, and blue. Therefore, it is advantageous to select a higher reflectivity for a partial wavelength range located around these maximal values, and the lowest possible reflectivity, preferably at least essentially zero, for the remaining wavelength range. The partial wavelength range located around the maximal values ​​is separated by an intermediate wavelength range. The partial wavelength range around the maximal values ​​can have a width of, for example, 40 nm, particularly 30 nm, preferably 20 nm, and most preferably 5 nm. This has the advantage that a wider spectral width, and therefore more natural ambient light, generally reaches the eye. In effect, this increases transparency without reducing the efficiency of the system. These maximal values ​​can be designed to have reflectivity up to 100%, for example, with an average transmittance of 90%, without significantly reducing the average transmittance.

[0034] Therefore, it is particularly advantageous to combine the higher reflectivity described with narrow spectral maxima of the primary colors of the display unit (such as the aforementioned red, green, and blue). For example, the emission spectrum of the display unit may be selected so that the maxima have a maximum of 40 nm, particularly a maximum of 20 nm, preferably a maximum of 10 nm, and especially preferably a maximum full width at half maximum (FWHM) of 2 nm. Ideally, the display unit (or the light from the display unit used for the virtual image) has more than three maxima. In addition to further enhanced transparency to natural ambient light, this spectral limitation has the advantage that dispersion color correction does not have to be performed over a wide wavelength range, but is performed only over small ranges (e.g., three) within the wavelength range (particularly blue, green, and red), thus significantly simplifying the process.

[0035] Therefore, when micromirror elements are arranged and configured in a medium such as a liquid, light is dispersed due to the wavelength dependence of the change in refractive index. Light from the display unit strikes the gas-liquid interface at a certain angle, is then reflected by the micromirror elements, and generally takes on a new angle. At this new angle, the light re-enters the gas-liquid interface and exits it at a different third angle. This is known from dispersion prisms, where the wavelength of light is split. This splitting must be corrected in the optical system of the spectacle display system. This is particularly advantageous when the spectral range to be corrected can be as small as possible, because it is especially desirable that one or more micromirror elements reflect only small spectral peaks or reflect only around small spectral peaks. This allows for high system efficiency, high system clarity, and high image quality to be achieved through simplified dispersion correction.

[0036] In a further embodiment, the reflective surfaces are specified to have at least partially different sizes, i.e., different widths and / or different heights. In particular, one or more reflective surfaces closer to the user's central visual axis in a neutral position facing forward may be smaller in size than one or more reflective surfaces further away from the user's central visual axis. In order for the virtual image to be visible, the light emanating from the output hole of the display unit must be deflected into the pupil of the eye through each micromirror element. This results in a relationship between the maximum size of each micromirror element and the diameter of the output hole of the display unit. In an advantageous embodiment, each reflective surface may be selected to be as close as possible to or equal to the maximum size. The maximum size is smaller closer to the central visual axis than further away from it. This takes advantage of the fact that each virtual subimage that can be seen through only one micromirror element has fewer mirror transitions that must connect to adjacent subimages. These subimages must be computed for each transition to avoid artifacts. Therefore, reducing the number of micromirror elements reduces this computational burden. Diffraction effects caused by beam truncation when the beam only partially hits the micromirror within the edge region of each micromirror element are also minimized. Therefore, in designs with fewer micromirror elements, these diffraction artifacts are minimized, enabling improved display of virtual images and thus improving immersion.

[0037] In particularly advantageous embodiments, the number of micromirror elements is reduced to one, i.e., a single micromirror element is directed towards each eye. Correspondingly, the size of the reflective surface may be larger in this case than that described above. That is, the diameter of the reflective surface, especially the total height and / or width, may be greater than 10 mm. Reducing the number of micromirror elements also has the advantage that the alignment of one micromirror element does not need to be adjusted to match that of adjacent micromirror elements. Therefore, the precision of the micromirror alignment only needs to meet the requirements for directing light to the pupil, and does not need to meet the more stringent requirement of minimal deviation from the alignment of adjacent micromirror elements. Furthermore, diffraction effects at the boundaries between adjacent micromirror elements are avoided, resulting in higher image quality. The optical efficiency is tripled because the overlap of three adjacent micromirror elements requires three times the optical redundancy. Eliminating the overlap of adjacent micromirror elements also allows for simplification of the optical system. Furthermore, manufacturing is also simplified because there are no manufacturing tolerances for adjacent micromirror elements.

[0038] In another embodiment, the reflective surface is a concave reflective surface. Alternatively or in addition, the reflective surface can be a flat reflective surface. A concave reflective surface enables particularly high optical efficiency. This makes it possible to ensure that light from just one physical pixel of the display unit is imaged onto each micromirror and then deflected from there to the user's eye position directed towards the virtual image in a targeted manner. Thus, in this case, multiplexing is not necessary. A concave reflective surface may also be selected to focus directly onto the display unit. This eliminates the need for additional optical elements, but all one or more micromirror elements simultaneously image the display unit. As a result, a multiplexing method must be used to clearly image the pixel information (light from the physical pixels of the display unit) in one line of sight direction.

[0039] A planar reflective surface is particularly advantageous when an additional focusing unit is provided in the optical path between the display unit and the deflection unit, for example, to solve convergence-accommodation inconsistencies and / or to compensate for the user's visual impairment. The additional focusing unit allows the focus of the virtual image to always be adjusted to the position in the current line of sight. For this purpose, information about the orientation of the eye ("target tracking") may be used, as described below. Preferably, the focus for the entire virtual image is uniformly changed, for example, by using an electrically adjustable liquid-controlled lens ("liquid lens"). However, other optical approaches are also possible, for example, by stacking several transparent displays. With a planar reflective surface, any focal length of the display unit can be displayed without causing imaging errors—other known beam splitter techniques, such as waveguides, must be designed to accommodate a given focal length.

[0040] By using additional focusing units, particularly liquid-controlled lenses, the user's visual impairment can be dynamically compensated (i.e., individually for different users) regardless of the resolution of the convergence-accommodation contradiction problem. In this case, the additional lens element must be placed in the optical path of peripheral light from the field of view to the eye between the environment and the deflection unit. Here, for example, the user may intend to wear conventional glasses over the AR glasses or use a corresponding attachment for vision correction. Vision correction can be further fine-tuned by providing an additional lens element between the display unit and the deflection unit.

[0041] In one embodiment, the support structure and / or other components surrounded by one or more micromirror elements and / or liquid are shaped so that ambient light from the user's field of view passes through the interface between the transparent material and the liquid and / or the interface between the liquid and the transparent material at least largely at a small angle, particularly at least largely less than 45°, from a given subregion of the field of view. Thus, ambient light strikes the aforementioned interface at very shallow angles at only a few points, ideally no points at all, and at steep angles at as many points as possible, ideally everywhere. Since ambient light strikes the aforementioned interface from different regions of the field of view at different angles, particularly important parts can be selected for a designated subregion, for example, the region surrounding the user's central line of sight. This means that a geometric shape is selected for the carrier structure and / or one or more micromirror elements and / or other components that minimizes perceptible refraction and diffraction effects, and therefore further reduces the visibility of the aforementioned components due to the aforementioned effects.

[0042] In a further embodiment, it is specified that the reflective surfaces of at least some of the multiple micromirror elements, particularly most of these micromirror elements, overlap in an orthogonal projection onto a plane extending across the user's central line of sight. This applies when the micromirror elements or reflective surfaces are oriented parallel (parallel as much as possible in the case of physical contact). Overlapping the micromirror elements can reduce diffraction effects and increase resolution. Preferably, the micromirror elements overlap only within a region where the micromirror elements are sufficiently tilted during intended use (e.g., within a region of angular alignment used, such as that specified by the actuator element), so that no physical contact occurs during operation. In particular, it may be specified that the reflective surfaces do not overlap within a region where they are perpendicular to the central visual axis at least at a given point in time during intended use.

[0043] It can be stipulated that the reflective surfaces of multiple micromirror elements overlap within the environment of the user's central visual axis in orthogonal projection. This design is advantageous because, in the typical position of the display unit on the side of the eyeglass frame, the micromirrors visible when looking straight ahead are tilted sufficiently so that overlapping is mechanically possible. Then, towards the side of the temple, there is an area where overlapping is not possible. Therefore, due to the reduction of overlap and the resulting diffraction effect, higher resolution can be achieved in the area of ​​looking straight ahead, which is advantageous for use in AR glasses. In addition, when looking to the side, people turn their heads and eyes midway through the period, rather than turning their eyes to look to the side, and this is combined with looking along the central visual axis ("straight ahead"), which means that improved resolution along the central visual axis ("straight ahead" line of sight) improves immersion.

[0044] In one embodiment, one or more micromirror elements are arranged and configured on a one-dimensional or two-dimensional curved surface. In addition to or alternatively, support structures and / or common actuator elements may extend along a one-dimensional or two-dimensional curved surface. Furthermore, sealed housing elements may extend along a one-dimensional or two-dimensional curved surface, as is known from standard eyeglasses with curved lenses. The curved surface can be defined as a two-dimensional manifold in three-dimensional space. One or more micromirror elements are therefore arranged and configured to be at least partially offset from one another in the direction of the central viewing axis. This is particularly advantageous in combination with the overlapping micromirror elements described above, as it allows overlap (with the advantages described above) to be achieved over a larger area, i.e., for more micromirror elements.

[0045] In a further embodiment, the housing element has an anti-reflective coating on the side facing the display unit, particularly an anti-reflective coating having locally varying anti-reflective properties. Light from the display unit is typically coupled to the deflection unit from the side of the temple and then reflected at one or more micromirror elements, so reflection also occurs at the interface between the air and the transparent material of the housing element. Depending on the position of the pupil, this reflection is visible at different positions and is undesirable, but can be sufficiently reduced by the anti-reflective coating. This also reduces artifacts and enhances immersion.

[0046] In one advantageous modification, the display unit can emit polarized light, particularly linearly polarized light, and undesirable reflections can be further reduced by using an anti-reflective coating suited to this. It is also advantageous to appropriately align the polarization direction to minimize reflections. In this way, undesirable reflections can be almost completely avoided if the direction of light emission with respect to the side of the housing element facing the display unit is selected to be as close as possible to the Brewster angle according to the overall geometric shape of the spectacle display system. Anti-reflective coatings are also typically applied to conventional spectacle lenses to allow viewing of the natural environment. Therefore, in a spectacle display system, it is advantageous to select a coating that allows for both low reflection when normally viewed and low reflection of light emitted by the display unit. Since the reflection of light emitted from the display unit is only visible in a small area, a locally variable coating is advantageous that eliminates the reflection of light emitted by the display unit in a virtually complementary area of ​​the field of view, improving clarity in the remaining area.

[0047] In one embodiment, the glasses display system comprises an eye-tracking device for determining the orientation of the user's eyes, and a control unit for controlling a deflection unit according to the result of determining the eye orientation. This allows light to be directed specifically towards the pupil of the eye, which increases light efficiency and avoids undesirable effects such as "eye glare" where a third party sees the deflected light reflected in the user's eyes. Due to the improved energy efficiency, for example, the weight of the battery and for example, the required size of the display unit can be reduced, resulting in improved immersion.

[0048] It may also be specified that the control unit is designed to control the display unit according to assignment rules stored within the control unit. The assignment rules may specify the assignment of each virtual pixel of the virtual image to each physical pixel of the display unit, which changes depending on the eye orientation. Thus, the content of the virtual pixels is specified by different physical pixels (and therefore at different times) for different eye orientations. This is because, as one or more micromirror elements move, the assignment of the physical pixels of the display unit to the virtual pixels of the virtual image is always changed, and in a different way for each combination of pixels. This non-linear change is compensated for by the assignment rules so that the virtual pixels in the virtual image maintain their desired positions. This improves image quality and, in particular, enables the use of large virtual images.

[0049] In one embodiment, an aperture unit, which can be adjusted using a control signal, may be provided in the optical path of light between the display unit and one or more tiltable micromirror elements, or within the display unit. The adjustable aperture unit is designed to adjust at least one beam position and / or at least one beam width assigned to each beam position for light deflected by the reflective surfaces of one or more tiltable micromirror elements according to the control signal. Thus, the adjustable aperture unit can be used via the adjustable beam position to determine the arrangement of light striking a deflection unit or other optical system such as a microlens array, e.g., the display unit, and therefore which of the one or more micromirror elements the light strikes, and / or via the adjustable beam width to determine the size of the area on the deflection unit that is struck by the light. This means that some micromirror elements near the beam position may be excluded from being illuminated by light, for example, one or more micromirror elements that would receive only a small amount of light if the beam width is larger (as described in more detail below).

[0050] This has the effect that, using control signals and adjustable aperture units (which may also be called adaptive apertures), the emission holes of the display unit can be set to be dynamically, i.e., variable with respect to time, by the control signals. As described above, multiplexing can also be implemented when using a display unit having an emissive display with a downstream microlens array, along with the corresponding benefit of enhanced spatial resolution. This combines the advantages of different technical approaches.

[0051] Generally (i.e., when viewed without an aperture unit), the output aperture of the display unit is visible as a mirrored image through one or more micromirror elements. If the output aperture is very large, any multiplexing that may be required becomes more complex, and the weight of the AR glasses increases without adding any value. Therefore, when designing the output aperture (i.e., its diameter), it is desirable to achieve the smallest possible diameter. If the output aperture of the display unit is too small, it will not be possible to project a virtual image in any direction of the user's line of sight, which means that the virtually expandable field of view will be relatively small.

[0052] Therefore, the output aperture of the display unit requires a specific minimum size to make the optical paths from the display unit to the micromirror elements, and from the micromirror elements to the eye, usable for all AR viewing angles, i.e., the largest possible virtually complementary field of view. Thus, the pixel image information is projected onto the deflection unit, one or more micromirror elements (collectively, a "micromirror array") as a beam of light having the diameter of the output aperture of the display unit. A typical diameter of the output aperture is, for example, 8 mm. A typical diameter of a micromirror element or its reflective surface is 2-4 mm. Thus, the beam of pixel image information can strike multiple adjacent micromirror elements simultaneously. Each of the one or more micromirror elements is ideally aligned according to the current orientation of the eye so that the central optical beam from the pupil is imaged at the center of the output aperture of the display unit, so it is possible that light from pixel image information striking two adjacent micromirror elements simultaneously can also be seen simultaneously in the eye. However, because adjacent micromirror elements are aligned in different ways, the same pixel image information is perceived in two different directions of reflection, resulting in one or more virtual ghost images.

[0053] The adjustable aperture unit ensures that only the cropped light beam is projected onto different micromirror elements or microlenses of the microlens array for each pixel image information, so that as little light as possible strikes each (next) adjacent micromirror element or microlens, or only light that does not strike the pupil and is therefore invisible.

[0054] Therefore, it is advantageous to design an adjustable aperture unit for each of one or more micromirror elements such that the light striking each micromirror element is given only a line of sight direction to a virtual image covering a larger area than that on other (nearest) adjacent micromirror elements. Extreme line of sight directions that primarily (i.e., at least largely) strike adjacent micromirror elements and only slightly, for example, graze, the micromirror element being viewed (at a given time) should, accordingly, no longer strike the output aperture of the display unit. Thus, the small output aperture of the display unit can be selected for each micromirror element viewed at each multiplexing point in time, for example, within a time-multiplexing framework, to improve image quality. This is achieved using an adjustable aperture unit and / or microlens array.

[0055] This has the advantage that diffraction effects during image formation are minimized, and the maximum clarity of the virtual image can be achieved. This is because the micromirror elements, which originally deflect only a small portion of the entire beam emitted to the eye by the display unit, act as apertures. In other words, the beam can be blocked when it is only partially reflected. It is known in optics that diffraction increases when the aperture is small. Therefore, it is advantageous to position the beam on the micromirror elements using an aperture unit that can be adjusted so that the beam is not blocked, or is only partially blocked, by the micromirror elements.

[0056] In another embodiment, the adjustable aperture unit is designed to adjust the beam position by adjusting the position of at least one partial aperture region within the entire aperture region, which can be switched to transparent or opaque using a control signal, and which is transparent, i.e., can be switched to transparent using a control signal. The remaining region of the entire aperture region complementary to at least one partial aperture region is opaque, i.e., can be switched to opaque using a control signal. Thus, one or more partial aperture regions can be switched to transparent so that only these partial aperture regions transmit light from one or more pixel image information items assigned to each partial aperture region, and other pixel image information items do not reach the deflection unit. As described below, the arrangement of one or more transparent partial regions changes over time, thereby enabling, for example, a time-multiplexing method. This has the advantage that, for example, crosstalk of pixel image information, which results in the ghost images described above, is avoided or at least reduced. This improves image quality even with large fields of view and enhances system immersion.

[0057] The features and combinations of features described, including those described in the general introduction, as well as features and combinations of features disclosed in the diagrams or solely in the diagrams, may be used not only individually or in the described combinations, but also together with other features or without some of the disclosed features, without departing from the scope of the invention. Consequently, embodiments that may be produced by distinct combinations of individual features disclosed in the diagrams, but not explicitly shown and described in the diagrams, are also part of the invention. Therefore, embodiments and combinations of features that do not include all the features of the initially formulated independent claims are also considered disclosed. Furthermore, embodiments and combinations of features that deviate from the combinations of features or exceed those described in the dependent claims are also considered disclosed.

[0058] In the context of this disclosure, phrases such as “across / along” may be understood as “at least substantially perpendicular / parallel,” i.e., “perpendicular / parallel” or “substantially perpendicular / parallel,” i.e., perpendicular / parallel except for a specified deviation. The specified deviation could be, for example, up to 15°, preferably up to 5°, and particularly preferably up to 3°. Thus, in the context of this disclosure, phrases such as “oriented in the opposite direction” may be understood as “oriented at least substantially opposite direction,” i.e., “oriented at least substantially antiparallel.” Furthermore, the restriction “essentially” may refer to a maximum allowable deviation on a percentage basis, e.g., up to 15%, preferably up to 5%, and particularly preferably up to 3%.

[0059] The following sections will describe exemplary embodiments in detail with reference to schematic diagrams. [Brief explanation of the drawing]

[0060] [Figure 1] This is a top view of a plan view of an exemplary embodiment of an eyewear display system. [Figure 2] This is a top plan view of an exemplary embodiment of an eyewear display system having offset and overlapping micromirror units. [Figure 3] This figure illustrates the optimization of the geometric shape of a micromirror unit to reduce visibility. [Figure 4] This is a top plan view of an exemplary embodiment of an eyewear display system having an additional focusing unit and vision correction function. [Figure 5] This figure shows the illustrative refractive indices of liquids and transparent materials as a function of wavelength. [Figure 6] This figure shows the proportional Fresnel reflection as a function of the incident angle with respect to the example wavelength. [Figure 7] This figure shows the wavelength-dependent refractive effect as a function of the incident angle and wavelength. [Figure 8] This is a top view of a plan view of an exemplary embodiment of an eyewear display system having a concave reflective surface. [Figure 9] This is a top view of another exemplary embodiment of an eyewear display system having a concave reflective surface. [Figure 10] This figure illustrates the deflection of a micromirror unit using a guide matrix structure. [Figure 11] Front and interior views of another exemplary embodiment of an eyewear display system. [Figure 12] This is a top plan view of an exemplary embodiment of an eyewear display system having exactly one micromirror element for each eye. [Modes for carrying out the invention]

[0061] In the diagram, identical or functionally identical features are indicated by the same reference symbol.

[0062] Figure 1 is a top plan view of an exemplary embodiment of an eyewear display system for, for example, one half, i.e., one eye. For both eyes, the system can be appropriately complemented symmetrically.

[0063] Figure 1a shows one half of the spectacle display system 1, for example, the left half viewed from above, or the right half viewed from below. Rays 163', 161', and 162' are emitted by the display unit 14 (located laterally in this case), which are then imaged by the optical system 13 such that the rays 163', 161', and 162' are (partially) reflected onto the pupil 11 of the eye 10 by one micromirror element of the deflection unit 17, or, in the illustrated example, multiple micromirror elements such as 12, 12', and 12'. The optical system 13 may include one or more lenses and / or mirrors and / or other optical components such as one or more aperture units (which are also adaptive, i.e., controllable by control signals). The optical system 13 may also include, or be, a microlens array having multiple microlens elements and / or a projector optical system, as illustrated in the general description.

[0064] Here, the eye is oriented in the central line of sight direction B (which is parallel to the y-direction). If one or more micromirror elements 12, 12', 12' (for example, having typical dimensions of about 2 mm) are designed to transmit at least substantially ambient light, it is possible to view the natural environment 100 according to rays such as 161', 162', 163', and the ambient light rays 161', 162', 163' can be superimposed with the virtual image by the rays 161', 162', 163'. The optical system 13 may be designed so that the virtual image can be viewed clearly at a finite or infinite distance. The micromirror elements 12, 12', 12' are mounted so as to be tiltable, allowing them to be arranged in two dimensions.

[0065] One or more micromirror elements 12, 12', 12', and a support structure 200 for the micromirror elements 12, 12', 12' (Figure 10), not shown for clarity, are arranged and configured within a sealed housing element 17a filled with liquid 23. The liquid 23 is selected so that the refractive index of the material of the micromirror element and the liquid are as identical as possible. It is known that when immersed in a liquid with nearly identical refractive indices, the glass component becomes invisible. This results in two effects. On the one hand, Fresnel reflection that occurs during transitions from one medium to the other medium with a different refractive index disappears. Secondly, light rays are not refracted by material transitions. However, even very small differences, if the angle at the interface is very flat, still leave the possibility of partial and total internal reflection. This is illustrated and explained in detail in Figure 6.

[0066] In the present invention, in conjunction with determining the orientation of the eye 10 and thus the position of the pupil 11 using the eye-tracking device 15, it is possible to direct the rays 163', 161', and 162' from the optical system 13 to the pupil 11 of the eye 10 with great precision. In the event of eye movement, for example, lateral eye movement where the position of the pupil 11 changes, as shown in Figure 1b, one or more micromirror elements 12, 12', 12' are positioned so as to ensure that the rays 163', 161', and 162' from the optical system 13 accurately strike the pupil 11 again. In addition to the carrier structure for the micromirror elements 12, 12', 12', the micromirror elements 12, 12', 12' also include one or more actuator elements (not shown for clarity) for adjusting the angular arrangement, and thus the respective reflection angles, and in this case, also include separate angle sensors (not shown) for measuring the current angular arrangement.

[0067] This enables the use of a control loop to track one or more micromirror elements 12, 12', 12' so that rays 163', 161', 162' from the optical system 13 strike the pupil 11 of the eye 10. For this purpose, the position of the pupil 11 is measured using an eye-tracking device 15, and the target angular arrangement of the micromirror elements 12, 12', 12' is calculated using a control unit and compared to the actual positions of the micromirror elements 12, 12', 12'. The actuator elements then compensate for the difference between the ACTUAL and TARGET values, aiming for a speed fast enough to allow the virtual image to be perceived as stable even when the eye 10 is moving. The maximum speed of the eye is known to be 1000° / s, from which the minimum processing speed can be derived.

[0068] When the angular arrangement of one or more micromirror elements 12, 12', 12' changes, the new orientation of the eye 10 also changes the line of sight, which will then deviate from the central line of sight direction B. Comparing Figure 1a and Figure 1b, we can see that in Figure 1a the ray 161' is reflected as ray 161, and in Figure 1b it is reflected as ray 161b, and rays 161b and 161 have different directions. As a result, the assignment of each virtual pixel of the virtual image to each physical pixel of the display unit 14 changes, and the image information emitted by the display unit 14 in direction 161' must be adapted to the changed angular arrangement or orientation.

[0069] Therefore, when eye movements occur, not only should the orientation of one or more micromirror elements 12, 12', 12' be adjusted, but the pixel light image information generated on the display unit 14 should also be adjusted. However, since the geometric arrangement configuration from the projector to the micromirrors is known, the laws of optics can be used to calculate what new image information must be displayed so that a human viewer has the impression that the virtual image is not distorted at a given position of the pupil (a designated "eye box"), and the corresponding assignment rules can be stored in the control unit of the display unit 14.

[0070] One or more micromirror elements 12, 12', 12' are preferably controlled so that the central line of sight beam, i.e., the line of sight beam starting from the center of the pupil and striking the assigned micromirror element at the center, is deflected toward the center of the optical system 13, for example, along the ray 163b in Figure 1b. Since changes in the tilt of the micromirror elements 12, 12', 12' change the angle at which the pixel image information from the display unit 14 is seen, as described, it may be advantageous for the micromirror elements 12, 12', 12' to be adjusted in steps rather than continuously, based on a threshold that determines how far off-center the ray 163b can strike the pupil 11 of the eye 10. It is advantageous that the eye makes small movements, and as a result, does not need to be compensated for. It is also advantageous that the micromirror elements 12, 12', 12' are embedded in the liquid 23, which has a damping effect and suppresses vibrations (i.e., small, sharp angular movements).

[0071] One or more micromirror elements 12, 12', 12' are depicted in a plane in Figure 1. However, they can also be arranged on a one-dimensional or two-dimensional curved surface, as shown in Figure 2. The micromirror elements 12, 12', 12' are arranged offset from each other in the central line of sight direction traversing the main extension plane (here the xz plane) of the deflection unit 17. For example, two, some, or all of each adjacent micromirror element 12, 12', 12' are arranged offset with respect to each other. This is advantageous because eyeglass lenses typically have a curved surface known as the base surface, and therefore the eyeglass display system 1 can be designed to be more similar to conventional eyeglasses. Furthermore, this also allows more of the micromirror elements 12, 12', 12' to overlap each other, and / or the degree of overlap of each adjacent micromirror element 12, 12', 12' to be increased.

[0072] Figure 3A shows different geometric shapes of one or more micromirror elements, along with the results for undesirable refraction and reflection effects. Liquid 23, having a refractive index nearly identical to that of the material of the micromirror elements 12, 12', eliminates Fresnel reflection that occurs during transitions from one medium to the other with a different refractive index, and the light rays 21, 21', 22, 22' are not refracted.

[0073] However, even very small differences still leave the possibility of partial and total internal reflection when light rays strike each interface at a very flat angle. For example, ray 22' is shown as such a partially reflected ray. Thus, Figure 3a shows two micromirror elements 12 and 12' having different shapes. Both micromirror elements 12, 12' achieve a translucent reflective surface 25 by, for example, applying a thin metallic coating to the micromirror elements 12, 12'. The micromirror elements 12, 12' themselves are made of, for example, plastic or glass having a first refractive index that matches as closely as possible to the second refractive index of the surrounding liquid 23.

[0074] The difference between the two exemplary micromirror elements 12 and 12' in Figure 3a lies in their geometric design, so that micromirror element 12' forms an interface where the visible light rays of the human eye 10 corresponding to the light beam 22 strike the optical interface at a flat angle. In this case, total or partial reflection may occur depending on the actual angle. These reflections cloud the transparency of the deflection unit 17, as partial reflections superimpose ghost images. Therefore, it is advantageous for the mechanical structure of the micromirror element to be designed so that the visible light rays pass through the interface with refractive index transitions as orthogonally as possible. Thus, the geometric shape of micromirror element 12, which has a rounded rear side, is preferred over the rectangular geometric shape of micromirror element 12'.

[0075] Figure 3b shows an alternative geometric shape of the micromirror element 12'. Here, the micromirror element 12' has a trapezoidal geometric shape in the illustrated cross-section, where the longer side of the trapezoid corresponds to the reflective surface 25. The light beam 23 passing through the two parallel bases of the trapezoid runs parallel to the front and back of the micromirror element 12' and to the front and back of the deflection unit. However, the light beam 23' passing through only the long base and one of the legs of the trapezoid does not run parallel because the boundary surface of the leg passes at an angle that is too flat. Therefore, the trapezoidal geometric shape of the micromirror element 12' is preferable to the rectangular geometric shape of the micromirror element 12', but is less preferable to the geometric shape of the micromirror element 12 having a rounded back surface.

[0076] Figure 4 is a top plan view of an exemplary embodiment of an eyewear display system having an additional focusing unit, and in this case, a visual acuity correction function. The additional focusing unit 13' as an adaptive optical system is focused by the control unit 110. For example, the focus of the virtual image can be set to either infinity (beam path / light beam 112) or a finite distance (beam path / light beam 111). This solves the convergence accommodation contradiction problem. If the focus can be adjusted faster than the image update rate, different focal planes can be set within the virtual image.

[0077] If a lens element 13' is added between the deflection unit 17 and the environment 100, visual acuity correction can be incorporated with little effort. Its characteristics then must be taken into consideration by the control unit 110.

[0078] Figure 5 shows examples of refractive indices for a liquid, in this case oil, and a transparent material, in this case quartz glass, as a function of wavelength in nanometers from 400 nm to 700 nm at exemplary temperatures. Curve 80 corresponds to the first refractive index of the liquid 23, and curve 81 corresponds to the second refractive index of the material of one or more micromirror elements 12, 12', 12'. Note that the maximum difference between the first and second refractive indices is reached here at 400 nm and does not exceed a relatively small amount of 0.004. It is particularly advantageous when the two curves 80, 81 intersect in the green wavelength range (520 nm to 565 nm) because artifacts in the green wavelength range have been found to be perceived by humans with higher resolution than in the red and blue ranges. For these refractive indices, the values ​​exemplified in Figures 6 and 7 for Fresnel reflection and refraction effects are obtained as a result, which results in mostly invisible material transitions, and therefore mostly invisible micromirror elements 12, 12', 12', and mostly invisible carrier structures or mostly invisible housing elements 17a. It should also be noted that at this point, reflections may also occur on the inside 17b (Figure 1) of the housing element 17a facing the user and display unit 14 as a boundary layer. These cause interference due to the y-direction offset of the inside 17b with respect to the micromirror elements 12, 12', 12'. These interference reflections can be reduced or eliminated using anti-reflective coatings, as commonly used on conventional eyeglasses.

[0079] In Figure 6a, curve 82 shows the Fresnel reflection as a percentage of the total intensity with respect to the angle of incidence in degrees for two refractive index combinations from Figure 4 at a wavelength of 450 nm. The difference in refractive index here is approximately 0.002. It is clear that the percentage of reflected intensity increases exponentially due to this effect. The reflection is close to zero up to an angle of incidence greater than 80°, and increases to 100% in the range of a few degrees from 90°, i.e., when the light strikes almost flatly, barely grazing the boundary layer (the angle of incidence is measured with respect to the direction perpendicular to the interface).

[0080] Figure 6b shows that a portion of the reflected light is less than 0.01% up to approximately 70°, meaning that Fresnel reflection does not play a significant role below this angle of incidence. Figure 6b shows the Fresnel reflection as a percentage of total intensity per degree of incidence ("per degree of incidence") for two refractive index combinations from Figure 4 for wavelengths of 450 nm from 0° to 70°. Curve 82a shows the curve for s-polarized light, and curve 82b shows the curve for p-polarized light.

[0081] In addition to Fresnel reflection from Figure 6, the refractive effect must also be considered, which similarly depends on the angle of incidence and wavelength. Therefore, Figure 7 shows the wavelength-dependent refractive effect, i.e., the degree-based deflection ("degree-based change in direction"), as a function of the degree-based angle of incidence ("degree-based angle of incidence") and wavelength from 400 nm to 700 nm. The temperature and refractive index again correspond to the temperature and refractive index in Figures 4 and 5. The solid curves 83a...83i...83z represent the deflection when light is incident from an optically dense medium to an optically thin medium for wavelengths from 400 nm (curve 83a) to 700 nm (curve 83z). The dashed curves 84a...84i...84z represent the deflection when light strikes an optically dense medium from an optically thin medium for wavelengths from 400 nm (curve 84a) to 700 nm (curve 84z).

[0082] Distractions in the core region W near 0° are limited to approximately 1 / 60° = 0.0167, which are imperceptible to the user due to the angular resolution of the human eye and therefore insignificant. Thus, for example, curves 83i and 84i show that incident angles up to approximately 38° for wavelengths greater than 550 nm cannot be perceived by the user and are therefore insignificant. From such representations, the optimized geometric shapes for one or more micromirror elements 12, 12', and 12' can be derived in accordance with the overall geometric shape of the glasses display system 1.

[0083] Figure 8 is a top plan view of an exemplary embodiment of an eyewear display system having a concave reflective surface. The illustrated principle allows for the avoidance of multiplexing methods.

[0084] This approach is particularly light-efficient because all of the light rays 163', 161', and 162' are directed towards the pupil 10 of the eye 11. For this purpose, the optical system 13' is designed so that light from the display unit 14 is projected onto the intermediate image 101. However, the intermediate image 101 does not need to be sharply focused. For example, it may be advantageous to compensate at this point for imaging errors caused by subsequent reflections on the curved micromirror elements 12, 12', 12'. The intermediate image 101 is selected so that it is imaged onto the pupil 11 of the eye 10 by the curved micromirror elements 12, 12', 12'. Due to the geometric arrangement of the pupil position relative to the micromirror elements 12, 12', 12' and the diameters of the pupil 11 and the micromirror elements 12, 12', 12', the resulting fields of view 102 and 103 are covered by the micromirror elements 12 and 12', respectively. The intermediate image 101 is positioned so that the adjacent field of view areas 102 and 103 do not overlap. Therefore, the light rays 163', 161', and 162' of the physical pixels of the display unit 14 are only imaged onto one micromirror element 12, 12', 12', and no further multiplexing is required.

[0085] In the embodiment shown in Figure 8, each light beam 104, 105 has its own intermediate focus 106, 107, which is mapped to its own physical pixel on the display unit 14. Such a light beam 105 strikes not only one micromirror element 12 but also another micromirror element 12', which is again mapped to another physical pixel on the display unit 14, thus requiring redundant physical pixels, i.e., more physical pixels are represented in the virtual image than are represented in the virtual image.

[0086] In one modified form, the intermediate image 101 may also be designed so that adjacent field of view regions 102 and 103 overlap. The corresponding micromirror elements 12 and 12' are then designed so that the same intermediate focal point 107 is used for the same field of view angle corresponding to the pupil 11, and thus only one physical pixel is required for each field of view direction. This design has more stringent optical requirements, as not only must the micromirror elements 12, 12', and 12' produce sharp images, but distortion must be controlled so that adjacent micromirror elements 12, 12', and 12' with different inclination angles reproduce a common intermediate image 101. When designing the optical system 13', it can be taken advantage of the fact that maximum sharpness must be achieved only in the central region, the so-called "foveal region," i.e., when the eye 10 is precisely positioned with each micromirror element 12, 12', and 12'. When the eye 10 is turned away, human imaging ability rapidly deteriorates, so in this case, image errors are usually not perceived.

[0087] Figure 9 is a top plan view of another exemplary embodiment of an eyewear display system having a concave reflective surface, similar to that shown in Figure 8, but optionally without the optical system 13'.

[0088] One or more micromirror elements 12, 12', 12' are designed to focus directly onto the display unit 14. Additional optical elements 13'' may be inserted to improve image quality. Thus, all micromirror elements 12, 12', 12'' are imaged onto the display unit 14 simultaneously. Therefore, a multiplexing method must be used to clearly image pixel information in the line of sight. A multiplexing method based on a switchable and adaptable aperture unit is suitable for this purpose, so that unwanted micromirror elements 12, 12', 12' are hidden at any given time, and the aperture unit is transparent only to the desired micromirror elements. Such a switchable and adaptable aperture unit may be implemented, for example, using a liquid crystal shutter.

[0089] In different embodiments, the focal points of one or more micromirror elements 12, 12', 12' may therefore be located at different distances. Figure 8 shows an example where the focal point 101 is located in front of the display unit 14. In Figure 9, the focal point is located on the display. The focal point may be located behind the display unit 14 at infinity. The focal plane can therefore be freely selected to be in front of, above, or behind the display unit 14. When pixel information is mapped simultaneously onto multiple micromirror elements 12, 12', 12''', a multiplexing method, such as those described in the last paragraph, is required to clearly display the pixel information in one image direction.

[0090] Figure 10 illustrates the deflection of one or more micromirror units using a guide matrix structure.

[0091] Figure 10a shows an example of a micromirror unit 12 configured to be tiltable around two tilt axes K1 and K2, positioned on a carrier structure 200. A two-dimensional guide matrix structure 202, each having guide surfaces 203a, 203a', 203b, 203c, and 203d, is formed on a common actuator element 201 (Figure 10b). Each micromirror unit 12, 12', 12' probes the guide matrix structure 202 in the form of associated guide surfaces 203a, 203a', 203b, 203c, 203d with each sensor 204a, 204a', 204b, 204c, 204d, with one sensor provided for each tilt axis K1, K2, and thereby, when the actuator element 201 is displaced, each micromirror unit 12, 12', 12' can be tilted nonlinearly from the displacement of the actuator element 201 in different ways from each other according to the spatial shape of the guide surfaces 203a, 203a', 203b, 203c, 203d.

[0092] Figure 10b illustrates this in a cross-sectional view with respect to one dimension of the inclination. For example, when the actuator element 201 is displaced in the negative x-direction, two micromirror units 12, 12' are tilted counterclockwise, and the other micromirror unit 12' is tilted clockwise.

[0093] Figure 11 shows another exemplary embodiment of the eyewear display system. As can be seen in Figure 11a, the eyewear display system 1 in this example comprises a deflection unit 17 having multiple micromirror units 12, 12', 12' configured to be positioned over a large area of ​​the field of view corresponding to the field of view of conventional eyeglasses. Figure 11b shows an internal view of the deflection unit 17 having a number of micromirror units 12, 12', 12'. Adjacent micromirror units 12, 12' are shown here as an example and some overlap. In the illustrated example, one or more micromirror units 12, 12', 12' are configured to be positioned offset in the y direction and also have different sizes. Micromirror unit 12' has a larger reflective surface than micromirror unit 12', and micromirror unit 12' has a larger reflective surface than micromirror unit 12.

[0094] Corresponding to Figure 1, Figure 12 shows a top plan view of an exemplary embodiment of the eyewear display system for, for example, one half, i.e., one eye. For both eyes, the system can be appropriately symmetrically complemented. In this embodiment, the deflection unit 17 has only one micromirror element 12 (for each eye, and therefore a total of two micromirror elements). The components of this embodiment may correspond to the components of the embodiments in Figure 1 or any other figure unless otherwise stated.

[0095] Similar to Figure 1a, Figure 12a shows one half of the spectacle display system 1, for example, the left half viewed from above, or the right half viewed from below. Rays 163', 161', and 162' are emitted by the display unit 14 (located laterally in this case), which are then imaged by the optical system 13 so that the rays 163', 161', and 162' are (partially) reflected onto the pupil 11 of the eye 10 by just one micromirror element of the deflection unit 17 in the illustrated example.

[0096] As shown in Figure 1a, the eye is oriented in the central line of sight direction B (parallel to the y-direction here). Here again, if the micromirror element 12 is designed to transmit ambient light at least substantially, it is possible to see the natural environment 100 according to rays such as 161', 162', 163', and the ambient light rays 161', 162', 163' can be superimposed with the virtual image by rays 161', 162', 163'. The micromirror element 12 is mounted in a tiltable manner, allowing it to be positioned in two dimensions.

[0097] Corresponding to the embodiments in Figures 1a and 1b, when the orientation of the eye 10 changes the line of sight direction, which deviates from the central line of sight direction B, the angular arrangement of the micromirror elements 12 also changes. Comparing Figures 12a and 12b, it can be seen that in Figure 12a, the ray 161' is reflected as ray 161, while in Figure 12b, it is reflected as ray 161b, and rays 161b and 161 have different directions. As a result, the assignment of each virtual pixel of the virtual image to each physical pixel of the display unit 14 changes, and the image information emitted by the display unit 14 in direction 161' must be adapted to the changed angular arrangement or orientation. [Explanation of Symbols]

[0098] K1, K2 tilt axis 1. Eyeglass display system 10 eyes 11 Pupil 12, 12', 12' micromirror elements 13 Optical system 13' optics 13' Focusing Unit 13'' optical element 14 Display Unit 15 Eye-tracking devices 17 Deflection Unit 17a Housing element 17b inside 21, 21', 22, 22' rays 23 liquid 25 Translucent reflective surface 80 curves 81 curve 82 curve 83a curve 83i curve 83z curve 84a curve 84i curve 84z curve 101 Intermediate image 102 and 103 field of view areas 104, 105 Light beams 106, 107 intermediate focus 110 Control Unit 111 Beampath / Optical Beam 112 Beampath / Optical Beam 161', 162', 163' rays 161', 162', 163' rays 163b Ray of light 200 Support structure 201 Common Actuator Elements 202 Two-dimensional guide matrix structure 203a, 203a', 203b, 203c, 203d Guide surfaces

Claims

1. Eyewear display system (1) for displaying a virtual image within the user's field of view, - A display unit (14) for emitting light rays (163', 161', 162') in the emission direction as computer-generated image information, - A deflection unit (17) for deflecting light rays (163', 161', 162') emitted by the display unit (14) as computer-generated image information (162') toward the user's eye (10), wherein at least one micromirror element (12, 12', 12') can each be tilted within a carrier structure (200), and each has at least one reflective surface (25) for deflecting light rays (163', 161', 162') emitted by the display unit (14) as computer-generated image information, Equipped with, The at least one micromirror element (12, 12', 12') and the support structure (200) are arranged within a sealed housing element (17a) of the deflection unit (17), the sealed housing element (17a) is filled with liquid (23), - The at least one micromirror element (12, 12', 12') or the support structure (200) is made from or using the respective transparent materials having a first refractive index. - The liquid (23) has a second refractive index that conforms to the first refractive index in the sense of the smallest possible deviation, - An eyewear display system (1) wherein the deviation between the first refractive index and the second refractive index is smaller than the maximum limit value in the green wavelength range.

2. - Each of the at least one micromirror element (12, 12', 12') and / or the support structure (200) transmits at least substantially ambient light from the user's field of view and is invisible to the user in at least one wavelength range and / or at least one angular range of the ambient light, and is made of or using the respective transparent material. - The eyewear display system (1) according to claim 1, further characterized in that the liquid (23) is at least substantially transparent to the surroundings, and in particular the second refractive index is equal to the first refractive index for at least one wavelength in the green wavelength range.

3. The eyewear display system (1) according to any one of claims 1 to 2, characterized in that at least one micromirror element (12, 12', 12') is mechanically coupled to an actuator element (201).

4. The eyewear display system (1) according to any one of claims 1 to 3, characterized in that the deflection unit (17) comprises exactly one micromirror element (12, 12', 12') for each eye.

5. The eyewear display system (1) according to any one of claims 1 to 4, characterized in that each of the at least one micromirror elements (12, 12', 12') has a coating on a reflective surface (25) whose reflective properties are matched to the emission spectrum of the display unit.

6. The eyewear display system (1) according to any one of claims 1 to 5, characterized in that the reflective properties of the coating are matched to the maximum value of the emission spectrum.

7. The eyewear display system (1) according to any one of claims 1 to 6, characterized in that the support structure (200) and / or the at least one micromirror element (12, 12', 12') is shaped so that ambient light from the user's field of view passes through the interface between the transparent material and the liquid (23), and / or the interface between the liquid (23) and the transparent material, at least mostly at a small angle, and particularly at least mostly at an angle of less than 45°.

8. The eyewear display system (1) according to any one of claims 1 to 7, characterized in that the deviation between the first refractive index and the second refractive index is smaller in the green wavelength range than in any other subrange of the visible spectrum, in particular all other subranges.

9. The eyewear display system (1) according to any one of claims 1 to 8, characterized in that the maximum limit value for the deviation in the green wavelength range is 0.005, particularly 0.

002.

10. The eyewear display system (1) according to any one of claims 1 to 9, characterized in that the support structure (200) and / or the common actuator element (201) extend along a one-dimensional or two-dimensional curved surface.

11. The eyewear display system (1) according to any one of claims 1 to 10, characterized in that the housing element (17a) has an anti-reflective coating on the side (17b) facing the display unit (14), particularly an anti-reflective coating having locally changing anti-reflective properties, and / or an anti-reflective coating that conforms to the polarization from the display unit.

12. - An eye-tracking device (15) for determining the orientation of the user's eye (10), - An eyewear display system (1) according to any one of claims 1 to 11, characterized by a control unit for controlling the deflection unit (17) according to the result of determining the orientation of the eye (10).

13. The eyewear display system (1) according to any one of claims 1 to 12, wherein the control unit is also designed to control the display unit (14) in accordance with assignment rules stored in the control unit, the assignment rules specify the assignment of each virtual pixel of the virtual image to each physical pixel of the display unit (14) which changes in accordance with the orientation of the eye (10).

14. - In the standard operating mode, one of the micromirror elements (12) or at least almost all of the micromirror elements (12, 12', 12') are arranged in an angular configuration of the glasses display system (1) such that only light from the display unit (14) is directed to the user's eye (10) by each of the micromirror elements (12, 12', 12'), and / or - In a power-saving operating mode of the glasses display system (1), one or more of the micromirror elements (12, 12', 12') that are not illuminated by the display unit (14) are placed in a predetermined stationary position, and in the stationary position, the essentially sole light from the display unit (14) is directed towards the user's eye (10) when the eye (10) is in a stationary position, particularly when the actuator element (201) is stopped, the eyewear display system (1) according to any one of claims 12 to 13.

Images