Eyewear display system for displaying a virtual image in a field of view of a user, comprising an aperture scanner

Abstract

The invention relates to an eyewear display system (1) for displaying a virtual image in a field of view of a user, the eyewear display system comprising: a display unit (14) for emitting light (163", 161", 162") as computer-generated image information in an emission direction; a deflection unit (17) for deflecting the light (163'', 161'', 162'') emitted by the display unit (14) as computer-generated image information into an eye (10) of the user; a plurality of micromirror elements (12, 12', 12") which can each be tilted in a support structure and which each have a reflective surface (25) for deflecting the light (163'', 161'', 162'') emitted by the display unit (14) as computer-generated image information; wherein an aperture unit (70), which is arranged in an optical path of the light (163'', 161'', 162'') between the display unit (14) and the tiltable micromirror elements (12, 12', 12") and can be adapted by means of a control signal, is designed to adapt at least one beam position (70b', 70b'', 70b*) of the light deflected by the reflective surfaces (25) of the tiltable micromirror elements (12, 12', 12") according to the control signal, in order to provide an eyewear display system (1) which offers improved immersion.

Description

[0001] title

[0002] Glasses display system for displaying a virtual image in a user's field of view with an aperture scanner

[0003] Scope of the invention

[0004] The disclosure relates to a spectacle display system for displaying a virtual image in a field of vision of a user, comprising a display unit for emitting a light as computer-generated image information in an emission direction and comprising a deflection unit for deflecting the light emitted by the display unit as computer-generated image information into an eye of the user, comprising a plurality of micro-mirror elements, each tiltable in a support structure, which each have a reflection surface for deflecting the light emitted by the display unit as computer-generated image information.

[0005] background

[0006] Glasses display systems for displaying a virtual image in a user's field of vision, "augmented reality glasses" or "AR glasses" for short, are able to overlay virtual objects in the form of virtual images onto the natural environment in the user's field of vision, thus virtually supplementing the field of vision. By displaying stereo images, these virtual objects can be placed freely in space. For this reason, it is advantageous to enable the largest possible virtually supplementable field of vision and a display with high (angular) resolution in order to create an immersive feeling through permanent visibility and spatially consistent positioning of the virtual objects, namely the feeling that the virtual objects are physical objects. The weight of such glasses in particular contributes to the immersive feeling, which can lead to an unnatural feeling for the user, especially when moving the head. The so-calledVergence accommodation problem is also a well-known effect that detracts from the immersive feeling.

[0007] The vergence accommodation problem exists in all 3D displays that show 3D objects using two stereo images. The 3D information, i.e., the distance of the object from the eye, is determined by the shifted stereo images. This distance conflicts with the distance at which the eye is focused to see a sharp image. A related problem arises in AR applications where virtual 3D objects are integrated into a real 3D environment. If the focus distance of the stereo image does not match the focus distance for the real environment, both scenes—the real and the virtual—cannot be viewed simultaneously, even though they are spatially fixed at the same location in the environment.

[0008] According to the state of the art, various optical methods are known for projecting a virtual image into the field of view of the natural environment. However, it is a technically unsolved problem to make the necessary optics small enough to achieve the form factor and weight of normal glasses. Glasses that are too large represent a technical limitation of the possible applications, since, for example, one would not accept a large product on the face in every everyday situation. Excessive weight means that AR glasses can only be worn for a limited time. Exemplary solutions are described in DE 10 2020206 392 A1 or DE 102023 101 777 A1.

[0009] US Patent No. 10,623,707 B2 describes AR glasses with a high-resolution image for the central field of vision (fovea centralis) and a lower-resolution image area projected into the peripheral field of vision. For this purpose, the eye's gaze direction is measured using an eye-tracking sensor, and the projection optics are adjusted accordingly.

[0010] The publications US 20200186761 A1 and US 11422274 B2 present AR glasses that allow the focal length of the AR optics to be adjusted to display objects at different distances. Thus, a technical solution to the vergence accommodation problem is disclosed. US 20200186761 A1 also includes an eye-tracking module for measuring vergence eye parameters. Furthermore, it is proposed to use these measured values ​​to track the eye with optics to enable eye tracking for different eye positions.

[0011] The technical task is therefore to provide a glasses display system with improved immersion, in particular with minimized weight and the largest possible virtually augmentable field of view with the best possible image quality, as well as the possibility of addressing problems typical for AR glasses such as the vergence accommodation problem and / or the problem of visual acuity correction.

[0012] overview

[0013] This problem is solved by the subject matter of the independent claim. Advantageous embodiments emerge from the dependent claims, the description, and the figures.

[0014] One aspect relates to a spectacle display system for displaying a virtual image in a user's field of vision, comprising a display unit for emitting light as computer-generated image information in a radiation direction and a deflection unit for deflecting the light emitted by the display unit as computer-generated image information into an eye of the user. The radiation direction preferably runs at least substantially in the direction of the user's field of vision (forward, so the light is emitted into the field of vision). The deflection unit, with at least the micro-mirror elements mentioned below, is arranged in the user's field of vision (in front of the user's eye(s)) and serves to deflect the light back (backward) into the user's eye(s).

[0015] The deflection unit has a plurality of tiltable micro-mirror elements, each arranged in a support structure, which each have a reflective surface for deflecting the light emitted by the display unit as computer-generated image information into the user's eye. The reflective surface is permeable to ambient light emitted from the environment in front of the user in their field of vision towards the eye. The reflective surfaces can therefore be regarded as semi-transparent reflective surfaces. Accordingly, a micro-mirror element can also have multiple reflective surfaces. This is the case, for example, when the micro-mirror elements each have a substrate, in particular a glass substrate, with a coating. One side of the substrate can be coated and an opposite side of the substrate can be uncoated, for example.Accordingly, two reflections can occur, with one side as a reflection surface and the opposite side as another reflection surface.

[0016] The reflection on the coated side can be adjusted (technologically) as desired using a suitable coating (designed to achieve a desired optical effect). The reflection on the uncoated side is then based on a Fresnel reflection resulting from the change in the refractive index of the substrate and the surroundings (e.g., the liquid of the housing element mentioned below). For micromirror elements stored in liquid, the latter reflection is typically very low, since typical glass substrates and liquids have very similar refractive indices. Alternatively, the opposite side of the substrate can also be coated.For example, this can be a counterforce coating which, in contrast to a coating designed for optical effect, is designed to compensate for stresses that occur between the substrate and its coating on the one hand and that can lead to a curvature of the substrate. The reflective surface, which is technologically adjusted, can also be located within the volume of the micro-mirror element, so that a total of three reflective surfaces can then be present. In this case, two further reflections are present at the interfaces between the micro-mirror element and the environment (ideally the liquid). The further reflections can be of a subordinate nature, i.e. significantly weaker than the (main) reflection at the technologically adjusted reflective surface. For example, the further reflections can be one or more orders of magnitude weaker than the main reflection.It is also possible to apply a coating to one side and the opposite side designed to achieve a desired optical effect. This allows, for example, the (main) reflections on the front and back of the substrate to be technologically adjusted, i.e., their optical properties can be adjusted. Multiple coatings on one side of the substrate are also possible; accordingly, the micromirror elements can each have a multitude of reflective surfaces.

[0017] A multitude of micromirrors can be understood here, for example, as at least 20, at least one hundred, or at least one thousand micromirrors. The reflecting surfaces are small, as is typical for micromirrors, for example, <100 mm. 2 or <20mm 2Since the micromirrors are movably mounted in the support structure, the reflective surfaces can each be aligned with their angular orientation in two dimensions. This means that the light emitted by the display unit, the light from the display unit, can be redirected into the eye or pupil for different orientations and / or positions of the eye. Since the deflection unit is at least partially (i.e. partially or completely), in particular with the micromirror elements, arranged in an optical path of ambient light from the user's field of vision into the user's eye, the virtual image corresponding to the computer-generated image information in the user's field of vision can be overlaid with real objects in the environment, since the micromirror elements are at least partially transparent to light from the environment (ambient light) (as required for AR glasses).For a better immersive feeling with virtual images that are as large as possible and as free of artifacts as possible, the deflection unit and / or the display unit are controlled depending on the orientation of the eye(s), for example with the control unit described below.

[0018] Advantageously, all or at least a large proportion (preferably almost all) of the micro-mirror elements (in particular always and / or predominantly) are angularly aligned (at least in a standard operating mode of the spectacle display system) such that only light from the display unit can be directed into the user's eye. In the standard operating mode, this angular alignment can be provided regardless of whether the micro-mirror element(s) are illuminated by the display unit or not. This has the advantage that no light source placed elsewhere leads to a visible reflection in the eye. This avoids annoying light reflections visible as ghost images. This is particularly advantageous for applications in outdoor environments, where the sun, as a very bright light source, can lead to otherwise unpleasant stray light reflections.A resulting further advantage is that a high reflectance, for example a semi-transparent coating, can be selected for the reflection surfaces of the micro-mirror elements, since even with high reflectance, unwanted light reflections in the eye cannot be amplified.

[0019] In addition, a power-saving operating mode of the spectacle display system can be provided, in which (in particular only) micro-mirror elements not illuminated by the display unit are brought into a predetermined resting orientation. In the resting orientation, an actuator with the actuator element(s) mentioned below can then be fully or partially deactivated. For example, the micro-mirror elements can be brought into the resting orientation when no virtual image is displayed or the virtual image has large / prolonged black areas. Preferably, the micro-mirror elements are only moved again when they are illuminated again by the display unit. The resting orientation of the micro-mirror elements can be predetermined such that they correspond to a resting position of the respectively assigned eye.In the resting orientation of the micro-mirror elements, essentially only light from the display unit is directed into the user's eye when the eye is in its resting position. In this case, however, the reflection condition is not met and disruptive reflections of light coupled in from behind can occur. Undesired reflections of ambient light can therefore sometimes cause visual artifacts, but it has been shown that people predominantly keep their eyes in the aforementioned resting or neutral gaze position, so that the likelihood of artifacts occurring is minimized. Overall, it is therefore advantageous to select the resting orientation of the micro-mirror elements according to the resting position of the eye, so that the reflection condition into the exit aperture of the projector is met most of the time, even when the actuators are switched off.

[0020] Alternatively or additionally, a high-quality operating mode can also be provided in which the angular alignment of the micro-mirror elements is continuously adjusted, i.e., the micro-mirror elements are constantly tracked by the eye movements (e.g., even when no virtual image is displayed or the virtual image has large / prolonged black areas). It can also be provided that the glasses display system has a sensor device (e.g., a camera sensor device) that detects and / or evaluates the environment, for example, with regard to prevailing lighting conditions, as well as an automatic switching device that is designed to automatically switch back and forth between different operating modes based on one or more predefined switching criteria.For example, the switching criterion can be based on the probability of bright light spots (which can easily lead to distracting reflections) evaluated by the sensor device, so that power-saving mode is activated with a lower probability and high-quality operating mode with a higher probability. The environment can also be recorded and analyzed for location data; for example, bright light spots are more likely to occur when the glasses display system is used outdoors than indoors. By specifying an appropriate control scheme, power consumption and immersion can be optimized.

[0021] The display unit can have one or more preferably flat screen elements ("displays") for generating the light, but also one or more (laser) projector elements. In particular, the display unit can be a stereo display unit which is suitable for generating a virtual stereo image in the field of vision. For this purpose, the stereo display unit can have two screen elements or two (laser) projector elements, each of which is assigned to one of the two eyes of the user. For example, the screen elements or

[0022] (Laser) projector elements are each arranged on a temple unit of the spectacle display system, located to the side of the user. Ideally, the light from a light-generating pixel element of the display unit should only fall on one micro-mirror element and not be visible simultaneously via one or more neighboring micro-mirror elements. In the latter case, the same pixel information would be perceived from two different spatial directions, i.e., as two different virtual pixels (image points of the virtual image), since neighboring micro-mirror elements are generally tilted relative to one another at an angle other than zero, i.e., are aligned differently.

[0023] In one embodiment, it can be provided that the micro-mirror elements and the support structure are arranged in a sealed housing element of the deflection unit that is filled with a liquid. The housing element can be arranged in front of the user's eyes, similar to the lenses of conventional eyeglasses. Accordingly, the liquid, the micro-mirror elements, and the support structure are arranged in an interior of the housing element such that the micro-mirror elements and the support structure are surrounded by the liquid. The housing element is accordingly oil-tight and / or waterproof and is made of or with a material that is (at least substantially) transparent to the ambient light and the light of the display unit, as is the case with conventional eyeglass lenses. The micro-mirror elements and the support structure are also advantageously made of a transparent material, as will be explained again below.

[0024] The liquid bath of micro-mirror elements and support structure has a damping effect, suppressing vibrations and thus unwanted small, rapid changes in the angular alignment of the reflecting surfaces. This is advantageous because the eye performs sudden movements of up to 1000° per second and then rests. Furthermore, the liquid reduces a difference in refractive index at the material transition, i.e., the interface between the liquid and the micro-mirror or support structure. This reduces Fresnel reflections on the one hand, and other refractive effects on the other. Both the reduction of reflections and effects reduces the visibility of the elements or structures in the liquid bath, as is known, for example, from glass components immersed in water.This avoids artifacts in the field of view that would detract from the user's immersive experience, and makes the use of the micro-mirror element arrangement ("micro-mirror array") directly in front of the user's eyes in their field of view possible in the first place. However, the micro-mirror array enables the large-area virtual extension of the field of view with greater (angular) resolution for the virtual image and is thus a prerequisite for an immersive glasses display system with dimensions similar to those of commercially available glasses.

[0025] In a further embodiment, it is provided that the micro-mirror elements and / or the support structure and / or further components which are surrounded by the liquid or border the liquid (such as a side of the housing element facing the interior) are each (at least substantially) transparent to the ambient light from the user's field of vision, as also described above for the housing element. The micro-mirror elements and / or the support structure and / or further components are accordingly made from or with a respective transparent material with a first refractive index. In particular, the housing element and / or the micro-mirror elements and / or the support structure and / or the further components can be made from the same material, which facilitates the adaptation of the optical properties to one another.

[0026] The liquid is also (at least essentially) transparent to ambient light and has a second refractive index adapted to the first refractive index in order to ensure the smallest possible deviation. Accordingly, the liquid must be selected such that the second refractive index does not deviate from the first refractive index by more than a predetermined limit value of, for example, 0.005 over a predetermined wavelength range of, for example, 400 nm - 700 nm and / or a predetermined temperature range of, for example, 0° - 30°. The liquid can also be optimized for one or more sub-ranges of the respective ranges, for example, in the wavelength range of 540 nm + / - 30 nm and / or in the temperature range of 21° + / - 2°, having a second refractive index particularly similar to the first refractive index. In this sub-range, a smaller maximum limit value for the deviation can be specified accordingly, for example 0.002.Such liquids, called "refractive index matching liquids," are commercially available with desired properties. Accordingly, it may be advantageous to actively control the temperature of the micro-mirror array, i.e., to measure it and set a target temperature or target temperature range by heating or cooling. A temperature control device for the liquid may therefore 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., depending on the measured value and the predetermined temperature, either for heating or cooling. Thus, temperature-dependent deviations can be avoided or at least reduced.This means that the ambient light is refracted so little as it passes through the deflection unit that any change in the ambient light, particularly at least in the wavelength range of the ambient light and / or at least in an angular range of the ambient light and / or at least in the temperature range, is below the user's perception threshold. As a result, the material transitions and thus the micro-mirror elements and / or the support structure and / or other components surrounded by the liquid become virtually invisible to the user. Thus, the micro-mirror elements can be arranged over a large area in front of the user's eyes without disrupting their perception of the environment and thus of the virtual image, significantly improving the immersive experience when using the glasses display system.

[0027] In one embodiment, it can be provided that an aperture unit that can be adjusted by means of a control signal is arranged in an optical path of the light between the display unit and the tiltable micro-mirror elements. The adjustable aperture unit is designed to adjust at least one beam position on the deflection unit and / or at least one beam width associated with the respective beam position on the deflection unit for the light deflected at the reflection surfaces of the tiltable micro-mirror elements according to the control signal.The adjustable aperture unit can thus be used to determine the location of the light striking the deflection unit via the adjustable beam position and thus the micro-mirror elements the light strikes, and / or to determine the size of an area on the deflection unit onto which the light strikes via the adjustable beam width. This allows certain micro-mirror elements near the beam position to be excluded from being illuminated by the light, for example, micro-mirror elements which would only be illuminated to a small extent with a larger beam (as explained in more detail below). The adjustable aperture unit can be viewed or referred to as an aperture scanner, since it enables local scanning of the display unit orthe deflection unit, in which an effective aperture ("exit aperture") is set by the adjustable diaphragm unit and can also be dynamically adjusted with the dynamically adjustable beam width.

[0028] This has the effect that with the control signal and the adjustable aperture unit (which can also be referred to as an adaptive aperture), an exit aperture of the display unit that is effective at the micro-mirror elements can be set dynamically, i.e. in a time-varying manner, by means of a control signal.

[0029] In particular, the adjustable aperture unit can be arranged in an optical path from the display unit to the deflection unit between a projector optics and the display unit. As explained, the display unit may or may not have one or more optics. These optics of the display unit can be designed, in particular, to image the physical pixels of the display unit such that the corresponding virtual image point (pixel of the virtual image) can be perceived in the eye with the desired sharpness. The optics of the display unit can have (micro)lenses arranged in parallel in the beam path (as opposed to serially), in particular a microlens arrangement ("microlens array") with a plurality of microlens elements arranged in parallel in the beam path. Such microlens elements can, for example, have a diameter of less than 1000 μm, preferably less than 500 μm, and / or greater than 50 μm.

[0030] The projector optics can comprise one or more lenses (macroscopic compared to the microlens elements of the microlens array described above). Preferably, the display unit is not arranged in a focal plane of the projector optics onto which a parallel beam coming from the micromirror elements is imaged. Arranging the display unit in the focal plane of the projector optics promotes crosstalk between respective physical pixels of the display unit in different neighboring micromirror elements. In particular, the focal plane can be arranged between the adjustable aperture unit and the projector optics. The projector optics thus contribute to improved immersion by reducing the requirements for the adjustable aperture unit.

[0031] Alternatively or additionally, the projector optics can be designed to

[0032] 1 1 1

[0033] Imaging formula - = - + - to sharply image the micro-mirror elements on another focal plane. The adjustable aperture unit is then preferably used in the further

[0034] This allows the beam position and / or beam width to be particularly well adapted to the respective dimensions and / or positions of the micro-mirror elements, which improves image quality and thus immersion.

[0035] Through multiplexing, as can be implemented by the adjustable aperture unit, one and the same display area of ​​a display of the display unit can be imaged onto different micro-mirror elements at different times.

[0036] In general (i.e., when viewed without an aperture unit), the effective exit aperture of the display unit is visible to the eye as a mirror image across each micro-mirror element. If the exit aperture is chosen to be very large, any necessary multiplexing, for example, becomes more complex, and the weight of the AR glasses increases without any added value. When designing the exit aperture (i.e., its diameter), it is therefore desirable to achieve the smallest possible diameter. If the exit aperture of the display unit is too small, a virtual image cannot be projected for every direction the user is looking in. The virtually expandable field of view is therefore relatively small, or a large number of micro-mirror elements would result in gaps in the virtual image because not every (required) virtual pixel would result in a line of sight to a physical pixel.

[0037] The exit aperture of the display unit therefore requires a certain minimum size to enable a light path from the display unit to the micro-mirror element and from the micro-mirror element to the eye for all AR viewing angles, i.e., the largest possible virtually complete field of view. A pixel image information is thus projected as a beam of rays with the diameter of the display unit's exit aperture onto the deflection unit, onto the micro-mirror elements (the "micro-mirror array" as a whole). A typical diameter of an exit aperture, for example, is 8 mm. A typical diameter for micro-mirror elements or their reflective surfaces is 2-4 mm. Thus, the beam of rays from a pixel image information falls on several neighboring micro-mirror elements simultaneously.Since each micro-mirror element is ideally aligned, depending on the current orientation of the eye, so that the central visual ray from the pupil is projected into the center of the exit aperture of the display unit, it can happen that light from a pixel image information incident on two neighboring micro-mirror elements simultaneously can also be seen in the eye simultaneously. However, because neighboring micro-mirror elements are aligned differently, the same pixel image information is perceived from two different reflected directions, resulting in one or more virtual ghost images.

[0038] The adjustable aperture unit ensures that only a cropped beam of rays is projected onto the different micro-mirror elements for each pixel of image information, so that as little light as possible falls on the (nearest) neighboring micro-mirror elements, or only light that does not hit the pupil and is therefore not visible, or only such a small amount of light that this light is not perceived as disturbing.

[0039] It is therefore advantageous to design the adjustable aperture unit in such a way that for each micro-mirror element only viewing directions for the virtual image are provided in which the light striking the respective micro-mirror element takes up a larger area than on other, (nearest) neighboring micro-mirror elements. Extreme viewing directions which primarily (i.e. at least predominantly) strike a neighboring micro-mirror element and in doing so only hit the respective micro-mirror element being viewed (at a particular point in time) to a very small extent, for example just barely grazing it, should accordingly no longer hit the exit aperture of the display unit. Accordingly, a small exit aperture of the display unit can be selected for each micro-mirror element being viewed at a particular point in time, for example as part of a time multiplexing, in order to improve the image quality.This is achieved with the adjustable aperture unit. An example of such a case is illustrated in Fig. 7f.

[0040] This has the advantage that diffraction effects during image formation are minimized and maximum sharpness of the virtual image can be achieved. This is because a micro-mirror element, which only deflects a small portion of the total beam originally emitted by the display unit into the eye, acts as an aperture. This means that the beam can be clipped if it is only partially reflected. It is known from optics that if the aperture is chosen to be small, diffraction increases. It is therefore advantageous to position the beam on the micro-mirror element using the adjustable aperture unit in such a way that it is not or almost not clipped by the micro-mirror element. The diffraction effect is illustrated as an example in Fig. 7c.

[0041] In another embodiment, it is provided that the adjustable aperture unit is designed to adapt the beam position by adapting at least one position of at least one transparent partial aperture region, i.e. one switched transparent by means of the control signal, within an overall aperture region that can be switched transparent or opaque by the control signal. A remaining region of the overall aperture region that is complementary to the at least one partial region is opaque, i.e. switched opaque by means of the control signal. Thus, one or more partial aperture regions can be switched transparent, so that only these partial aperture regions are permeable to light from one or more pieces of pixel image information assigned to the respective partial aperture region, and other pieces of pixel image information do not reach the deflection unit.As described below, the location of the transparent sub-area(s) can vary over time, for example, to implement a time-division multiplexing process. This has the advantage of avoiding or at least reducing crosstalk of the pixel image information, which can result in the ghost images mentioned above, for example. This improves image quality even for large fields of view and increases the immersion of the system. As explained further below, the terms "transparent sub-area" and "opaque residual area" can also be understood to mean that the light in the sub-area and residual area is modified in a way other than absorption, such that light falling on transparent sub-areas is ultimately visible to the user and light falling on opaque residual areas is ultimately invisible to the user. As explained below, this can occur as an alternative to absorption, for example, by changes in the polarization properties of the respective light.

[0042] It can be provided that several different, in particular non-adjacent, partial aperture regions are switched transparent at the same time. For example, the simultaneously switched partial aperture regions can each correspond to one or more adjacent switchable pixels of one or more pixelated liquid crystal elements. Each of the simultaneously switched transparent partial aperture regions is preferably assigned to a different physical pixel of the display unit, i.e. transparent to light from a different physical pixel of the display unit. This increases the luminous intensity of the virtual image. In particular, the different simultaneously switched transparent partial aperture regions can belong to different groups of partial aperture regions, wherein the individual partial aperture regions of the different groups of partial aperture regions are assigned to different physical pixels of the display unit.In this way, time multiplexing can be implemented, in which the physical pixel of the display unit assigned to the respective group provides the computer-generated image information as light for the pixel of the virtual image assigned to the transparently switched partial aperture area of ​​the respective group of partial aperture areas at different times.

[0043] In a further embodiment, the adjustable aperture unit comprises or is a mechanoelectric aperture element. The mechanoelectric aperture element has an aperture that is displaced in a plane transverse to the optical path of the transmitted light when the beam position is adjusted, for example, by a micro-electro-mechanical mirror ("MEMS mirror"). Alternatively or additionally, also to the embodiments explained below with pixelated (in particular ferroelectric) liquid crystal elements, the aperture unit can comprise one or more switchable polarization diffraction gratings. When the beam position is adjusted, the transmitted light can be deflected in several different directions depending on an applied voltage.To achieve a lateral shift, an inverse diffraction grating is placed downstream of each diffraction grating, so that the first diffraction grating causes a change in angle, while the second grating compensates for this change. Offsetting these two diffraction gratings in the direction of the optical axis results in a lateral shift of the original aperture on a plane orthogonal to the optical axis. A corresponding technical implementation is published in: Guo, Qi, et al. "Fast switching beam steering based on ferroelectric liquid crystal phase shutter and polarization grating." Liquid Crystals 46.9, (2019): 1383-1388.In a further embodiment, it is provided that the adjustable aperture unit is designed to adapt, in addition to the at least one beam position, a beam width assigned to the respective beam position(s) for the light deflected at the reflection surfaces of the tiltable micro-mirror elements in accordance with the control signal. The beam width can be adapted in particular by adapting an area and / or a diameter of the at least one transparent partial aperture region assigned to the respective beam position within the overall aperture region that can be switched to be transparent (in particular transparent or opaque) by the control signal. The beam width can in particular also be adapted differently for different beam positions. This optimizes the image quality, in particular also for differently sized reflection surfaces of the micro-mirror elements at different beam positions.By depending on the control signal, the beam width can be adjusted (and / or specified) over time and / or for time-varying beam positions. This can improve the performance of a multiplexing process and increase image quality.

[0044] In one embodiment, the beam width of the emitted light in the optical path in front of the adjustable aperture unit is larger than the diameter of the reflecting surface(s) of the illuminated micromirror elements. This applies to parallelized light; otherwise, the beam widths at the reflecting surfaces with and without the aperture unit are compared. This allows the effective beam width to be optimized particularly well, since it is particularly easy to specify a beam position with favorable, i.e., large-area irradiation of one or more reflecting surfaces.

[0045] In one embodiment, the adjustable aperture unit is configured to adjust the beam width such that it is smaller than the diameter of the reflective surface(s) of the respective illuminated micro-mirror elements, in particular (in the case of micro-mirror elements with differently sized reflective surfaces) of one of the illuminated micro-mirror elements. This allows the light to be directed from the deflection unit into the eye with particularly few artifacts (e.g., ghost images), which increases image quality and thus immersion of the system.

[0046] In a further embodiment, it is provided that the adjustable aperture unit is designed to adjust the beam position and beam width for the light in such a way that at least (in particular always) a large portion of the light transmitted through the adjustable aperture unit illuminates the reflection surface of exactly one of the micro-mirror elements in the form of exactly one light beam. Alternatively, it can be provided that the transmitted light illuminates several micro-mirror elements in the form of several (in particular disjoint) transmitted light beams, wherein each of the transmitted light beams, with the beam position and beam width predetermined by the adjustable aperture unit, is illuminated precisely with at least a large portion of the light of the respective light beam. This can be achieved, for example, by simultaneously switching several partial aperture areas of the overall aperture area transparent.A majority can be understood to mean at least 50%, preferably at least 65%, particularly preferably at least 80%. This allows a particularly bright, sharp virtual image to be displayed. In both cases, the display unit can be switched off in certain areas, so that not only is the aperture unit prevented from (already generated, emitted) light from adversely affecting the deflection unit, but this is also achieved through more targeted emission of light. On the one hand, this is more energy-efficient, and on the other hand, depending on the geometric interplay of the user's line of sight and the geometry of the AR glasses, beam adjustment via the aperture unit alone or beam adjustment via the aperture unit in combination with beam adjustment via the partially switched off display unit delivers results that lead to better image quality.Area-by-area switching can also be used to create spatially separated virtual pixels at a given time, given a given adjustment or setting of the aperture unit with several spatially separated active physical pixels. Light from different physical pixels then passes through a transparent partial aperture area at a given time, creating virtual pixels at spatially separated locations. Area-by-area switching reduces artifacts and improves image composition.

[0047] In another embodiment, a frame rate is specified for the computer-generated image information; and the aperture unit is designed to adjust (in particular change) the beam width and / or beam position several times within the time period specified for an image according to the frame rate. The beam width and / or beam position are thus adjusted / changed at an adjustment frequency (“sub-frame rate”) that is higher than the frame rate, which results from the frame rate times the number of beam positions (which correspond to the scan positions of the exit aperture). The pixel image information of a pixel may then only be displayed in one or a few sub-images within an individual image (“frames”). In order to control the display unit, in addition to the pixel image information, a scan position, i.e.The angular deflection of the corresponding micro-mirror element(s) through which the light is transmitted by the aperture unit at the corresponding times must be known. The angular deflection then determines when the respective pixel image information is displayed, or vice versa, as is known from scanning processes.

[0048] In particular, if the exit aperture of the display unit is larger than the reflective surface of a micro-mirror element, there is more than one scan position for the exit aperture for each frame, where the light falls on a micro-mirror such that the corresponding pixel image information is visible to the eye only for this spatial direction reflected on the micro-mirror. Thus, in the form of the aforementioned (sub-frame) time-multiplexing, different virtual pixels of the virtual image can be technically realized by the same physical pixel of the display unit. This requires a display unit that, through its pixels, can display several (at least two) pieces of pixel image information in a sub-frame of the individual images in a manner synchronized with the change in the angular orientation of the micro-mirror elements (which function as exit aperture scanners).

[0049] This results in the special technical effect of creating more virtual pixels than physical pixels. For example, if the light is reflected from the side, a 50° field of view covered by the display unit may be necessary. If this field of view is doubled by the mirrors, then approximately only 50° / 100° = 1 Z of the virtual pixels is physically required, and all other virtual pixels are realized by time-multiplexing neighboring physical pixels. This has the advantage of allowing the use of a smaller display, enabling further miniaturization of the overall system.

[0050] It can be provided that the aperture unit is designed to adapt the beam position to at least three, in particular at least 7, preferably at least 10, and particularly preferably at least 200, most particularly preferably 400 different beam positions within the time period specified for an image according to the refresh rate. Respective transparent partial aperture regions can be assigned to the respective different beam positions. The number of transparent partial aperture regions determined by the number of beam positions can, for example, be switched to transparent simultaneously. This allows the light to be directed particularly flexibly onto the micro-mirror elements, so that particularly high image quality can be achieved.

[0051] The aperture unit can be configured to adjust the beam width and / or beam position at a frequency of at least 100 Hz, preferably at least 1000 Hz, particularly preferably at least 20 kHz. A frequency of at least 100 kHz is also possible. pLEDs are particularly suitable for this purpose, as they can be operated at a very high on / off switching frequency (currently up to 300 kHz) and thus achieve high brightness (light intensity).

[0052] Accordingly, a control unit can be provided which is configured to control the adjustable aperture unit using the control signal and the display unit using a further control signal according to a time-division multiplexing scheme, in which at least two virtual pixels of the virtual image are assigned to a physical pixel of the display unit. Time-division multiplexing thus ensures that light from a physical pixel is directed onto the reflective surfaces of different micromirror elements at different times.

[0053] For example, using a GPU as the control unit, an image can be calculated that is to be displayed as a virtual image. Each pixel of the image describes a piece of pixel image information that is to be displayed for a spatial direction in the user's field of vision. In the method presented here, however, the mirrors move continuously in order to direct the light into the viewer's pupil as the orientation of the eye changes. Although the radiation direction of the display unit is constant, the light rays deflected in the deflection unit are observed, and after each movement of a micro-mirror element, a new assignment of physical pixel to virtual pixel in the specified spatial direction must be calculated in order to display the image information in the specified spatial direction. For this purpose, the angular orientation or direction of each micro-mirror element must be known.For this purpose, the individual micro-mirror elements can be equipped with an individual angle sensor for measuring the respective angular orientation, or the micro-mirror elements can be controlled so precisely that the controlled position is known with sufficient accuracy. For example, the corresponding pixel-to-spatial direction assignment rule can be stored in a lookup table for each mirror position. The assignment rule can thus be used to specify an assignment of the respective virtual pixels of the virtual image to a respective physical pixel of the display unit that changes depending on the orientation of the eye. The content of a virtual pixel can thus be specified according to the assignment rule for different orientations of the eye (and thus at different times) by different physical pixels and / or by different micro-mirror elements or their angular orientation.

[0054] In the case of a resulting blend from one micro-mirror element to another micro-mirror element, the intensity of a beam of rays that hits both micro-mirror elements can be reduced in the eye because not the full area of ​​the beam of rays hits the eye, e.g. if, in the limiting case, half the beam of rays hits each micro-mirror element. This is illustrated as an example in Fig. 7c. Compared to a beam path in which the beam of rays hits the micro-mirror element in the middle, the observer's eye perceives a reduced intensity in this case. As explained further below, it can be advantageous to increase the physical brightness of the assigned physical pixel accordingly in this case, so that the user perceives a homogeneous image brightness.

[0055] In one embodiment, the aperture unit comprises or is one or more pixelated liquid crystal element(s), in particular with a bistable liquid crystal, which can be divided into individually switchable volumes. Pixels of such pixelated liquid crystal elements that can be individually switchable to transparent or opaque can, as the smallest switchable unit, individually or together with neighboring pixels, form partial aperture regions of the aperture unit that can be switched to transparent or opaque. One possibility is to arrange the pixelated liquid crystal element (and thus the aperture unit at least partially, i.e. partially or entirely) in the beam path close to the deflection unit, for example by integrating it into the spectacle lens.Another possibility is to arrange the pixelated liquid crystal element (and thus the aperture unit at least partially, i.e., partially or entirely) in the beam path near the display unit, for example, by integrating it into an optic of the display unit or arranging it on the optic. Arranging it in the beam path near a unit can, for example, mean arranging it in the 25%, in particular 10%, of the beam path closest to the respective unit. The advantage of the pixelated liquid crystal element is that the beam position and / or the beam width can be adjusted very quickly and very precisely, and thus individual micro-mirror elements can be easily "switched on" or "activated," i.e., used to display the virtual image by irradiating the individual micro-mirror element. This allows, for example, time-division multiplexing with good image quality to be realized.The liquid crystal element(s) do not have to be arranged in one plane. Depending on the distance between the nearest neighboring micro-mirror elements, degrees of freedom can arise which allow a more free positioning of the liquid crystal elements in different planes. By switching the aperture unit, in this case the liquid crystal element(s), it is only necessary to prevent a physical pixel of the display unit from being perceived via two micro-mirror elements at the same time. For this purpose, it can also be sufficient if one (or more) additional beam paths leading to the eye from a physical pixel are attenuated in intensity to such an extent that they are not perceived as disturbing (compared to a primarily perceived beam path from this or other physical pixels).

[0056] However, using a simple pixelated liquid crystal element near the deflection unit without any additional elements results in the problem that the AR glasses become opaque to ambient light, since most of the micro-mirror elements are "switched off" at one point in time during time-multiplexing. This results in very low transmission even at high scanning speeds.

[0057] To avoid this problem, one embodiment provides that the pixelated liquid crystal element is or comprises (in particular only) a switchable wave plate, and the diaphragm unit comprises, in addition to the liquid crystal element, a first and, in particular, also a second static polarization element, which, in the case of two polarization elements, are each transparent to different polarizations. For example, the first polarization element can be transparent to s-polarized light and the second polarization element to p-polarized light, or vice versa, or this can apply analogously to two other, for example, circularly polarized states. The first polarization element is arranged in the optical path between the display element and the pixelated liquid crystal element, preferably on the display unit and / or in the beam path near or in the display unit.The second polarization element is arranged in the optical path between the pixelated liquid crystal element and the micro-mirror elements, preferably at the deflection unit and / or in the beam path near or in the deflection unit.

[0058] If only the first polarization element is present, it is preferably arranged on the deflection unit and / or in the beam path near or in the deflection unit in the optical path between the display element and the pixelated liquid crystal element. The first polarization element can, for example, be transparent to s- or p-polarized light. In this embodiment, the first polarization element is arranged such that light deflected into the eye by the deflection unit also passes through it. In this embodiment, light perceived by the user thus passes through the first polarization element twice with the first but without the second polarization element. The switchable wave plate is then a switchable λ / 4 plate, whereby the light linearly polarized by the first polarization element is converted into circularly polarized light.When reflected at or in the deflection unit, the circular polarization is converted, i.e., clockwise rotating light is converted into counterclockwise rotating light, or vice versa. When the light passes through the switchable wave plate and the first polarization element again, the aperture unit, i.e., the switchable wave plate, can be adjusted to select which lights are transmitted through the aperture unit and which are not. Since the ambient light can be assumed to be unpolarized to a good approximation, the view of the natural surroundings remains unobstructed in this case.

[0059] The adjustable aperture unit is designed to adjust the beam position of the light incident on the micro-mirror elements by adjusting the polarization conversion properties of the overall aperture area (formed in particular by the liquid crystal element / wave plate with the second polarization element), either to convert the polarization in the transparent partial area(s) in combination with maintaining the polarization in the remaining area of ​​the overall aperture area that is different from the partial area(s), or vice versa. For example, in an embodiment with two polarization elements, unpolarized light emitted by the display unit can first be converted by the first polarization element into a first polarization, e.g., s-polarization. In the at least one transparent partial area of ​​the aperture unit, the polarization is converted, e.g.,brought into p-polarization, retained in the remaining area. In front of the micro-mirror elements, the light of both polarizations hits the second polarization element, which is only transparent to the light of the second polarization. By selecting the transparent partial aperture area, and knowing a geometric relationship between the display unit, aperture unit, deflection unit, and eye position, it is possible to set which micro-mirror elements are irradiated with light and which are not. The transparent partial aperture area is then specified in this case according to the above definition as the aperture area through which light falls (is transmitted), which ultimately reaches the user's eye and is thus visible due to the adaptable properties of the aperture unit in the transparent partial aperture area.The opaque residual aperture area is then defined in the present case according to the above definition as the aperture area through which light falls (transmits) and ultimately does not reach the user's eye and is thus invisible due to the adjustable properties of the aperture unit in the opaque residual aperture area.

[0060] The light of the second polarization reflected by the illuminated micro-mirror element is then superimposed with the (typically unpolarized) ambient light and, after passing through the second polarization element and the pixelated liquid crystal element, is beamed into the user's eye. Since the ambient light is also polarized, the AR glasses are darkened, similar to sunglasses, since only one polarization state, i.e., half of the light, can be transmitted by the second polarization element.

[0061] As an alternative to arranging the pixelated liquid crystal element near the deflection unit, one embodiment may provide for the pixelated liquid crystal element to be arranged near the display unit. This places the pixelated liquid crystal element in the beam path between the display unit and the deflection unit, but not in the beam path between the micro-mirror element and the eye. This avoids a dimming effect similar to that of sunglasses, as in the above embodiment.

[0062] In this case, the adjustable aperture unit can be used to scan the exit aperture of the display unit in discrete positions by successively switching different sub-areas of a total aperture area irradiated by the display unit transparent and making the respective remaining areas opaque. The transparent sub-areas can be circular, square, or hexagonal, for example. Sub-areas that are transparent to successive magazines can overlap. Thus, the transparent sub-areas form one or more sub-apertures at a time step.

[0063] As an alternative to the overlapping sub-apertures described in the last paragraph, the partial areas made transparent in successive magazines can also be selected to be disjoint. The exit aperture of the display unit is thus divided into adjacent areas or sub-apertures for scanning by the micro-mirror elements. This has the advantage that only a few sub-frames have to be displayed by the display unit, i.e. the requirements for the speed of the display unit and the necessary brightness intensity are lower. This takes advantage of the fact that light that falls simultaneously on a micro-mirror element and its nearest neighbor generally does not hit the pupil of the eye in both cases: Since a neighboring micro-mirror element has a different angular position, the light from the neighboring mirror generally hits next to the pupil in this case.The reduced minimum requirements for the display unit also have a positive effect on image quality.

[0064] The electrical structures required to switch the liquid crystal element can lead to diffraction effects in transmission, which can degrade the image. However, these diffraction effects can be influenced by selecting the size of the structures so that the diffraction orders do not reach the eye and are therefore invisible to the user. A particular advantage is that the micro-mirror elements are very small, so even slight angular deviations in the light passing through the aperture unit no longer reach the pupil of the eye.

[0065] In a further embodiment, the spectacle display system comprises an additional focusing unit, in particular with or consisting of an electrically adjustable, fluid-controlled lens, which is arranged in or on the display unit. The focusing unit is designed to shift a focal plane for the light emitted by the display unit according to an additional control signal. The focusing unit can accordingly be referred to as an adaptive focusing unit. The additional focusing unit can be designed, for example, to resolve the vergence accommodation problem and / or to compensate for a visual impairment of the user.

[0066] By choosing an adaptive aperture (in the form of an adjustable aperture unit) that is smaller than the pupil of the human eye (i.e., a transparent partial aperture area for the adjustable aperture unit that is smaller than the pupil), the depth of field of the projected image is increased. As a result, the virtual image is not only sharp at a defined distance, but over a certain area as perceived by humans. In this way, the image can be displayed in focus at different distances without an additional focusing unit, provided these distances lie within the depth of field, thereby advantageously solving the vergence accommodation problem. The beneficial effect of small effective apertures on depth of field can also be combined with a focusing unit to sharply depict areas larger than the depth of field at different distances in front of the eye.

[0067] Since the adaptive aperture unit and the eye's pupil limit the effective diameter of the optical path of a virtual pixel, the requirements for the projection optics are advantageously reduced. This allows for a large f-number in the projection optics, i.e., a large aperture, while a sharp image only needs to be guaranteed for a small area of ​​the optics. This simplifies the design and manufacture of the projection optics. A larger f-number also enables a shorter focal length and thus the use of a smaller display, which is advantageous for a miniaturized design.

[0068] The additional focusing unit allows the focus of the virtual image to always be adjusted to the position of the current viewing direction. Information on eye orientation ("eye tracking") can be used for this purpose, as described further below. Preferably, the focus is changed uniformly for the entire virtual image, for example, by using an electrically adjustable liquid lens. However, other optical approaches are also possible, for example, by stacking several transparent displays. Flat reflection surfaces allow any focus distance of the display unit to be displayed without causing aberrations. Other known beam splitter technologies, such as so-called "waveguides," in contrast, must be designed for a fixed, predetermined focus distance.

[0069] With the additional focusing unit, particularly the fluid-controlled lens, a user's visual impairment can be dynamically compensated (i.e., individually for different users) regardless of the resolution of the vergence accommodation problem. In this case, an additional lens element must be placed in an optical path of the ambient light from the field of vision to the eye, between the environment and the deflection unit. For example, it is conceivable that the user wears their conventional glasses for visual acuity correction over the AR glasses or uses a corresponding attachment. With additional lens elements between the display unit and the deflection unit, the visual acuity correction can be further refined.

[0070] If an additional focusing unit is present, it is particularly advantageous if the reflection surfaces are flat. This allows for the greatest possible flexibility and range of applications for the focusing unit. In contrast, concave reflection surfaces enable particularly high light efficiency. With concave reflection surfaces, the light from just one physical pixel of the display unit is imaged onto a respective micromirror, which then redirects it to the location in the user's eye intended for the virtual image. Accordingly, multiplexing is not required in this case. The concave reflection surfaces can also be selected to focus directly on the display unit. This eliminates the need for additional optical elements, but all micromirror elements image the display unit simultaneously.As a result, a multiplexing process must be used to map pixel information (the light from a physical pixel of the display unit) unambiguously in a single viewing direction. Regardless of the flat or concave shape, the reflecting surfaces can be of different sizes and / or at least partially overlap. A hexagonal shape is advantageous due to its good surface coverage.

[0071] In one embodiment, the glasses display system comprises an eye-tracking device ("eye tracking") for determining the orientation of the user's eye, as well as a control unit for controlling the deflection unit depending on the result of determining the eye's orientation. This allows the light to be directed specifically into the pupil of the eye, increasing light efficiency and avoiding undesirable effects such as "eye glow," in which third parties see reflections of the deflected light in the user's eye. Due to the improved energy efficiency, the weight of, for example, a battery, as well as the required size of, for example, the display unit, can be reduced, which also leads to improved immersion.

[0072] It can be provided that the control unit is also designed to control the display unit according to an assignment rule stored in the control unit. In this case, the assignment rule can specify an assignment of the respective virtual pixels of the virtual image to a respective physical pixel of the display unit that changes depending on the orientation of the eye. The content of a virtual pixel is thus specified by different physical pixels for different orientations of the eye (and thus at different times). This is because, when the micro-mirror elements move, the assignments of physical pixels of the display unit to virtual pixels of the virtual image are always changed, and in a different way for each pixel combination.This nonlinear change is compensated for by the mapping rule, so that the virtual pixels retain their desired position within the virtual image. This increases image quality and enables particularly large virtual images.

[0073] In a further embodiment, the display unit is configured to adjust the intensity of the light emitted toward the respective beam position for each beam position adjusted by the aperture unit. In particular, this can be done by aligning the light flux of the light arriving at different beam positions, either consecutively or simultaneously. The alignment is to be understood in the context of the virtual image to be displayed. Due to the aligned light flux for the different beam positions, the virtual image should be perceived by the user as having a uniform brightness; however, the virtual image may have brighter and darker image areas.The adjusted intensity serves to homogenize the image brightness in the sense of compensating for light losses caused by the aperture unit in the respective viewing directions and to achieve a two-dimensionally specified light intensity profile for the virtual image.

[0074] The described features and feature combinations, including those in the general introduction, as well as the features and feature combinations disclosed in the description of the figures or the figures alone, can be used not only alone or in the described combination, but also with other features or without some of the disclosed features, without departing from the scope of the invention. Consequently, embodiments that are not explicitly illustrated and described in the figures, but that can be created by separately combining the individual features disclosed in the figures, are also part of the invention. Therefore, embodiments and feature combinations that do not encompass all features of an originally formulated independent claim are also to be considered disclosed.Furthermore, embodiments and combinations of features are to be considered as disclosed which deviate from the combinations of features or go beyond those described in the dependencies of the claims.

[0075] In the context of this disclosure, "transverse / alongitudinal" can be understood as "at least substantially perpendicular / parallel", i.e., "vertical / parallel" or "substantially perpendicular / parallel", i.e., perpendicular / parallel except for a predetermined deviation. The predetermined deviation can, for example, be at most 15°, preferably at most 5°, particularly preferably at most 3°. Accordingly, "oppositely oriented" in the context of this disclosure can be understood as "at least substantially oppositely oriented", i.e., "at least substantially antiparallel oriented". The restriction "substantially" can also refer to a maximum permissible deviation specified as a percentage, for example, at most 15%, preferably at most 5%, particularly preferably at most 3%.

[0076] Detailed description

[0077] Exemplary embodiments are described in more detail below with reference to schematic drawings.

[0078] Fig. 1 is a plan view of an exemplary embodiment of a spectacle display system;

[0079] Fig. 2 is a further plan view of the embodiment of Fig. 1 in which an effective pixel multiplication is illustrated;

[0080] Fig. 3 is another plan view of the embodiment of Fig. 1 in which effective pixel merging is illustrated;

[0081] Fig. 4 is an additional plan view of the embodiment of Fig. 1 in which a combined use of a transparent partial aperture area is illustrated;

[0082] Fig. 5 a schematic diagram of the effect of finite aperture sizes;

[0083] Fig. 6 is a plan view of exemplary embodiments of a diaphragm unit;

[0084] Fig. 7 exemplary illustrations of different beam positions on a micromirror array;

[0085] Fig. 8 exemplary embodiments with a diaphragm unit arranged on the deflection unit;

[0086] Fig.9 is a plan view of an exemplary embodiment of a spectacle display system with additional focusing unit and prescription correction;

[0087] Fig. 10 shows another embodiment of a spectacle display system in a glare situation;

[0088] Fig. 11 is a front view and interior view of another exemplary embodiment of a spectacle display system;

[0089] Fig. 12 shows a further schematic illustration of an exemplary embodiment of a spectacle display system; and Fig. 13 shows a series of schematic diagrams illustrating different forms of multiplexing.

[0090] In the figures, identical or functionally equivalent features are provided with the same reference numerals.

[0091] Figure 1 shows a plan view of an exemplary embodiment of a spectacle display system, illustrating one half, i.e., one eye. The system can be expanded accordingly, symmetrically, for two eyes.

[0092] Fig. 1a shows one half of the spectacle display system 1, for example, the left half from above or the right half from below. Light 163", 161", 162" is emitted by a display unit 14 (here arranged laterally), which in this case is imaged by an optics 13 such that this light 163", 161", 162" is (partially) reflected by micro-mirror elements such as 12, 12', 12" of a deflection unit 17 and strikes the pupil 11 of the eye 10. The optics 13 can comprise one or more lenses and / or mirrors and / or other optical components. The eye is oriented in a central viewing direction B (here parallel to the y-direction).If the micro-mirror elements 12, 12', 12" (for example, with typical dimensions of approximately 2 mm) are designed to be at least substantially transparent to ambient light, then both a viewing of the natural environment 100 according to light rays such as 161', 162', 163' is possible, and a virtual image with light rays 161", 162", 163" can be superimposed on the light rays 161', 162', 163' of an ambient light. The optics 13 can be designed such that the virtual image can be viewed sharply at a finite or infinite distance. The micro-mirror elements 12, 12', 12" are mounted so as to be movably tiltable, so that their angular orientation can be adjusted in two dimensions.

[0093] In the present example, the micro-mirror elements 12, 12', 12" and a support structure for the micro-mirror elements 12, 12', 12" (not shown for reasons of clarity) are optionally arranged in a sealed housing element 17a filled with a liquid 23. The liquid 23 is selected in such a way that the refractive index between the micro-mirror element material(s) and the liquid is as identical as possible. It is known that glass components become invisible when they are immersed in a liquid that has a nearly identical refractive index. Two effects occur here. Firstly, the Fresnel reflection, which occurs when transitioning from one medium to another with a different refractive index, disappears. Secondly, light rays are not refracted at the material transition.However, even with very small differences, there is still the possibility of partial reflection and total internal reflection if the angles meet the interface very flatly.

[0094] In the present embodiment shown, in conjunction with an exemplary determination of the orientation of the eyes 10 and thus the position of the pupils 11 by means of an eye tracking device 15, it is possible to direct the light 163", 161", 162" of the optics 13 very specifically into the pupil 11 of the eye 10. In the event of an eye movement, for example a lateral eye movement as shown in Fig. 1b, with a changed position of the pupil 11, the micro-mirror elements 12, 12', 12" are aligned accordingly so that the light 163", 161", 162" of the optics 13 again hits the pupil 11 precisely.In addition to the support structure for the micro-mirror elements 12, 12', 12", the micro-mirror elements 12, 12', 12" are also equipped with one or more actuator elements (not shown for reasons of clarity) for adjusting the angular orientation and thus the respective reflection angles, and in the present case additionally with an individual angle sensor (also not shown here) for measuring the current angular orientation.

[0095] This enables a control loop for tracking the micro-mirror elements 12, 12', 12", so that the light 163", 161", 162" of the optics 13 hits the pupil 11 of the eye 10. For this purpose, the position of the pupil 11 is measured with the eye tracking device 15, and the target angular orientation of the micro-mirror elements 12, 12', 12" is calculated by a control unit and subsequently compared with the actual position of the micro-mirror elements 12, 12', 12". The actuator element(s) then regulates the difference between the actual and target positions, aiming for a sufficiently high speed so that the eye 10 can perceive the virtual image stably even when moving. Speeds of 1000% are known as the maximum eye speed, from which a minimum processing speed can be derived.

[0096] When the angular orientation of the micro-mirror elements 12, 12', 12" changes, the viewing direction also changes with the new orientation of the eye 10, which now deviates from the central viewing direction B. When comparing Fig. 1a and 1b, it is noticeable that the light 161" is reflected as light 161 in Fig. 1a and as light 161b in Fig. 1b, whereby the lights 161b and 161 differ in their direction. This has the consequence that the assignment of the respective virtual pixels of the virtual image to a respective physical pixel of the display unit 14 changes, and the image information emitted in direction 161" by the display unit 14 must be adapted to the changed angular orientation.

[0097] Thus, in the event of an eye movement, not only the orientation of the micro-mirror elements 12, 12', 12" should be adjusted, but also the pixel light image information generated on the display unit 14. However, since the geometric arrangement of the projector to the micro-mirror is known, the laws of optics can be used to calculate which new image information must be displayed so that the human observer at a given location of the pupil (given "eyebox") has the impression that the virtual image has not shifted, and a corresponding assignment rule can be stored in a control unit of the display unit 14.

[0098] The control of the micro-mirror elements 12, 12', 12" is preferably carried out in such a way that the central viewing beam, i.e. the viewing beam that starts from the center of the pupil and hits the associated micro-mirror element in the center, is deflected, for example, along light 163b in Fig. 1b, to the center of the optics 13. Since a change in the inclination of the micro-mirror elements 12, 12', 12" changes the angle at which a pixel image information is seen by the display unit 14, as explained, it may be advantageous not to continuously adjust the micro-mirror elements 12, 12', 12" but in steps based on a limit value that specifies how off-center the light 163b may hit the pupil 11 of the eye 10. It is advantageous that the eye makes micro-movements that do not need to be corrected as a result.It is also advantageous that the micro-mirror elements 12, 12', 12" are embedded in the liquid 23, which has a damping effect and suppresses vibrations (i.e. small, rapid angular movements).

[0099] Furthermore, in the present case, an aperture unit 70 that can be adjusted by means of a control signal is arranged in an optical path of the light between the display unit 14 and the tiltable micro-mirror elements 12, 12', 12" of the deflection unit 17. In the present case, the aperture unit 70 is arranged in the optical path or beam path near the display unit. This dynamically adjustable aperture unit 70 is designed to adjust at least one beam position for the light deflected at the reflection surfaces 25 of the tiltable micro-mirror elements 12, 12', 12" according to the control signal, as explained in more detail by way of example with reference to Fig. 2.

[0100] Figure 2 shows a further top view of the embodiment of Fig. 1, illustrating effective pixel multiplication. The exit aperture 41 of the display unit 14 is defined by the optics 13 used here. The aperture 41 is larger than the micro-mirror elements 12, 12', 12" or their reflection surfaces 25. Thus, the emitted light for a physical pixel 14a of the display unit 14 is a light beam with edge rays 60 that simultaneously impinges on several neighboring micro-mirror elements 12, 12', 12" and possibly others. The light beam thereby forms a pixel image information item of the display 14. Since neighboring micro-mirror elements 12, 12', 12" have different inclinations, the image information of the same physical pixel 14a becomes visible in the human eye 10 through several light beams 61, 62, and 63.However, this would occur at different surrounding positions 100a, 100b, 100c, which would cause the image information of pixel 14a to repeat for different spatial angles. This corresponds to artifacts known as ghosting.

[0101] Such artifacts can be prevented by the adjustable aperture unit 70, which, as a function of an adjustable aperture downstream in the beam path, adjusts or reduces the beam position of the light beam with the marginal rays 60, in this case also its diameter, so that only one of the micro-mirror elements 12, 12', 12" is illuminated. This can be achieved by switching a partial aperture area 70b (Fig. 6) transparent within a transparent and / or opaque switchable overall aperture area 70a (Fig. 6). The relationship between exit aperture 41, diameter 40 (Fig. 3) and size of pupil 11 is explained further below with reference to Fig. 5.

[0102] On the other hand, time multiplexing can also be implemented with the adjustable aperture unit 70 by making different partial aperture areas of the overall aperture area transparent at different time steps and making the respective remaining areas (which may include the partial aperture areas switched transparent at other time steps) opaque. Exemplary designs of the aperture unit 70 or the aperture area of ​​the aperture unit 70 are shown in Figs. 6a-6c.

[0103] In both cases, a unique, in particular one-to-one, assignment of pixel image information to a micromirror is established.

[0104] Figure 3 shows another top view of the embodiment of Figure 1, illustrating effective pixel merging. Alternatively or in addition to the case described in Figure 2, in which different virtual pixels can be generated with one physical pixel, it is also possible to form a virtual pixel with different physical pixels, whereby the different physical pixels and different transparent aperture areas can operate simultaneously or at different times in a time-division multiplexing process. This is described below.

[0105] The aperture unit 70 is adapted or adjusted in this case such that two partial aperture areas 70b, 70bb at the edge of the overall aperture area 70a are transparent, and a central remaining aperture area is opaque. Two different physical pixels of the display unit 14 (not shown) are active, so that a first light 161" (of the first pixel) passes through the aperture unit 70 in a first direction toward the deflection unit 17, and a second light 162" (of the second pixel) passes through the aperture unit 70 in a second direction toward the deflection unit. Since the two pixels are arranged at different locations, the two directions differ.

[0106] To better illustrate the functionality of the aperture unit 70, in addition to the lights or light beams 161", 162" transmitted in the configuration shown, the corresponding full lights or full light beams 161*, 162* are also shown. The full lights or full light beams 161*, 162* correspond to the light generated by the first or second physical pixel, respectively, which is transmitted by the aperture unit 70 when the entire aperture area 70a is completely switched to transparent. These full lights 161*, 162* have a beam width W that corresponds to the aperture of the aperture unit 70. Since this aperture and thus the beam width W is significantly larger than a micro-mirror element 12, 12', the full lights 161*, 162* strike several micro-mirror elements (not shown here) in the plane E.

[0107] By adjusting the position and / or size of the transparent partial aperture area(s) 70b, 70bb, a beam position and / or a beam width wl, w2 of the transparent partial aperture area(s) 70b, 70bb can be specified. This also specifies which micro-mirror elements 12, 12' the corresponding lights 161", 162" impinge on. Together with the respective angular orientation of the micro-mirror elements 12, 12' illuminated by the lights 161", 162", the viewing direction for the corresponding virtual pixel is specified.

[0108] In the example shown, the viewing direction for the virtual pixel at the ambient position 100a runs exactly in the middle between two micro-mirror elements 12, 12'. Both micro-mirror elements 12, 12' are tilted in such a way that the lights or light beams 161, 162 deflected or reflected by them run parallel to each other. Since the two micro-mirror elements 12, 12' are (nearest) neighbors, the lights 161, 162 merge into one another, thus being separated by a distance that is smaller than human resolving power. In the example shown, the resulting combined light beam 161, 162 thus has a beam width wl+w2 which corresponds to the sum of the individual beam widths. However, the beam width wl+w2 can also be smaller or slightly larger.

[0109] The shown generation of a virtual pixel using two physical pixels is also explained in Fig. 7d. Fig. 4 shows an additional plan view of the embodiment of Fig. 1, in which a transparent partial aperture area is used in combination. Shown here are three physical pixels A, B, C of the display unit 14 as an example. Their lights 161", 162", 163" each pass through the identically configured (same) transparent partial aperture area 70b. Since the different physical pixels A, B, C are arranged at different locations, their lights 161", 162", 163" are imaged onto different micro-mirror elements 12, 12', 12", which are arranged far apart from one another here, with the same aperture setting of the aperture unit 70. In doing so, they generate respective virtual pixels with a suitable angular alignment of the micro-mirror elements 12, 12', 12".This preferably occurs simultaneously, as this allows the switching frequency of the aperture unit to be reduced in time-division multiplexing. The result is that, with time-division multiplexing with an exemplary number of 100 different aperture settings, i.e., 100 different positions for the transparent partial aperture area 70b shown, 1 / 100 of the physical pixels of the display unit are active for the time of one position of the partial aperture area 70b, similar to a sparse matrix.

[0110] Figure 5 shows a schematic diagram of the effect of finite aperture sizes. In the spectacle display system shown in Figs. 1 and 2, three apertures interact: the diameter of the pupil 11, the diameter 40 of the respective micro-mirror element 12, 12', 12", and the exit aperture of the display unit 14, which is determined in this case by the optics 13. In Fig. 5, the corresponding optical system was drawn one after the other for clarity, with the optical axis 42, and the deflection ignored. Depending on the line of sight or viewing ray and the distance between the apertures, different apertures can limit the diameter of the relevant beam of emitted light. Viewing ray 44 at the top of Fig. 5, for example, is a limiting case as the maximum angle possible through the pupil 11 when viewing a mirror image with the mirror diameter 40 shown.However, viewing ray 44 does not fall on the aperture 41 of the optics 13 and thus no light can be emitted by the display unit 14 in this angular range. Instead, the viewing ray 43 has the maximum possible angle at which light from the aperture of the optics 13 is visible in the eye 10. However, a beam of rays (shown here with parallelized light) is relevant in order to increase the light intensity of the image and minimize diffraction effects. A full beam of rays 45 with edge rays 46 is shown in the center of Fig. 5. At the bottom of Fig. 5, a smaller beam of rays 48 is shown which, at the given angle, is limited by the size of the aperture 41 corresponding to the edge rays 47. It is therefore advantageous to select the largest possible aperture 41 of the optics 13 and thus open up many viewing angles with full brightness for the virtual image.However, this conflicts with the need for the smallest possible optics 13 to save weight and enable a slim AR glasses design. In this technical conflict, several adjacent micromirror elements 12, 12', 12" must be considered to ensure that a large, continuous image, i.e., without gaps due to missing virtual pixels, is visible to the eye 10. In this design, the aperture 41 of the optics is chosen to be as small as possible.

[0111] Fig. 6 shows a plan view of exemplary embodiments of an aperture unit. As shown in Fig. 6a, the adjustable aperture unit 70 here comprises an electrically adjustable or switchable overall aperture area 70a, which can be used for the purpose of a multiplexing process. For this purpose, the switchable overall aperture area 70a is used as an aperture, here with a diameter of 41. The switchable overall aperture area 70a is switched to transparent in a partial aperture area 70b and opaque in the remaining aperture area 70c. In this case, the size of the transparent partial aperture region 70b is selected such that a diameter of the beam bundle that can transmit through the transparent partial aperture region 70b - and thus the beam width of the light that is deflected at the deflection unit 17 - is less than or equal to the diameter 40 of the reflection surface 25 of a micro-mirror element 12, 12', 12".Since the diameter 41 is larger than diameter 40, there is also a position of the transparent partial aperture area 70b, and thus a beam position for the light deflected at the deflection unit 17, in which the resulting beam bundle only falls on one micro-mirror element 12 and not also partially on one or more adjacent micro-mirror elements 12', 12".

[0112] If, as shown in Fig. 6b, the transparent partial aperture region 70b is then additionally displaced step by step as a transmission region, e.g., along a spiral path 72, then for each viewing angle defined by a physical pixel, a position can be found for the transparent partial aperture region 70b at which the transmitted light only falls on one micro-mirror element 12 and is thus only deflected by this one micro-mirror element 12. The displacement of the transparent partial aperture region 70b can occur continuously or, as shown here, at discrete positions such as 71, 71', etc. If a light beam only falls on one micro-mirror element 12, then a virtual image of the associated physical pixel is created only at one surrounding position 100a (Fig. 2) and not at further surrounding positions 100b, 100c.

[0113] Fig. 6c shows an embodiment of a diaphragm unit with a liquid crystal element as the overall diaphragm region 70a. By means of a plurality of linear electrodes 70d, 70e, 70f, which are arranged one behind the other in the optical path with different orientations, a transparent partial diaphragm region 70b can be freely defined in size and position in the overall diaphragm region 70a. The electrodes define the pixel areas in which a liquid crystal of the liquid crystal element can be switched. In the case shown, with an orientation of the different linear electrodes 70d, 70e, 70f at an angle of 120° to one another, a hexagonal shape of the transparent partial diaphragm region 70b results. This is particularly advantageous with a hexagonal shape of the reflection surfaces 25. In addition, this technical implementation is advantageous because no transistors are required within the overall diaphragm region, as is the case, for example,This is the case with liquid crystal displays, because the electrodes 70d, 70e, 70f run to the edge and can be contacted there.

[0114] As can be seen from the relationships shown in Fig. 5, it can be advantageous to support a maximum beam intensity of 50% of the beam intensity available for each physical pixel for each micro-mirror element 12 (i.e. less than the maximum beam width of the light emitted by the pixel, in particular the parallelized light). This advantage arises from the size of the aperture 41 that must be designed under this restriction (cf. Fig. 6). If the aperture 41 is to be designed such that all beam widths or all bundle diameters are supported, then the aperture 41 becomes comparatively large. In this case, the diameter 41 would have to be selected to be large enough that even light beam 44 would strike the aperture. If, instead, the restriction is placed so that only light bundles with an intensity of up to 50% at the location of the mirror diameter 40 are to be supported, then the diameter 41 can be selected to be significantly smaller.This has a further advantage, as a truncated aperture causes greater diffraction, thus reducing the maximum achievable resolution. The resulting decrease in intensity in the virtual image can be compensated by increasing the light emission per area of ​​the display unit. Since the geometric conditions for each pixel are known, appropriate compensation is feasible, for example, using a lookup table previously generated through calibration.

[0115] As a starting point for the design of the size of the micro-mirror elements 12, 12", 12"' or their reflection surfaces 25, the requirement can be chosen that for a given effective exit aperture, at least 50% of the achievable intensity should always be achieved with only one reflection surface 25, if the viewing direction is aligned with the light beam centrally striking the micro-mirror element. It should always be ensured that a gapless virtual image should be createable. A gap can describe not only a missing virtual pixel, but also a virtual pixel with a lower intensity that can no longer be sufficiently compensated by a higher emitted intensity (a virtual pixel whose brightness thus deviates noticeably from a given brightness profile for the virtual image).

[0116] Additional boundary conditions include:

[0117] - the geometry of the relative arrangement of display unit 14 to deflection unit 17 to eye 10, and / or

[0118] - the smallest possible exit aperture of the display unit 14, and / or

[0119] - the smallest possible diffraction effects on the micro-mirror elements 12, 12', 12" (better for larger reflection surfaces 25), and / or

[0120] - the relative angular alignment of adjacent micro-mirror elements 12, 12', 12" (larger differences reduce the number of artifacts such as ghost images when light partially falls on adjacent micro-mirror elements 12, 12', 12"), and / or

[0121] - the step size of the adjustable aperture unit and thus a spatial distance between successive positions for the transparent partial aperture area(s) 70b in a time-multiplexing / scanning method (with a small step size, a position of the partial aperture area 70b and thus a beam position can always be found at which all light transmitted through the aperture unit 70 falls on only one micro-mirror element 12, 12', 12"), and / or

[0122] - the maximum switching speed for the entire aperture range 70a of the aperture unit 70 (a refresh rate of 60-120Hz should be achieved).

[0123] Figure 7 shows exemplary illustrations of different beam positions on a respective micromirror array. In the partial images, the positions of the various relevant apertures 11, 40, 41 are projected onto a projection plane E (Fig. 3), which essentially runs through the micromirror elements 12, 12', 12". The largest diameter is the projection 70a' of the entire aperture area 70a, the second largest diameter is the projection 11' of the pupil 11 with the central viewing point 11", and the smallest diameter is the beam position 70b', drawn as a projection of the transparent partial aperture area 70b, whose diameter corresponds to the beam diameter of the light transmitted through the aperture unit 70. The projection 11' corresponds to a virtual pixel, and the projections 70a', 70b' each correspond to a physical pixel of the display unit 14.For projection 70a', it is assumed that the entire aperture area 70a is completely transparent. The partial images show situations corresponding to different virtual pixels, i.e., different viewing directions.

[0124] It should be noted here that beams of light are drawn as circles. Due to the angular constellations, in reality they are often ellipses, although beams of any shape are conceivable depending on the aperture. For the sake of simplicity and clarity, this aspect is ignored in the illustrations, and the functionality is explained using circular geometries.

[0125] Figure 7a shows a situation in which a virtual pixel is observed which is arranged such that the viewing point 11" essentially hits the micro-mirror element 12 shown centrally. With a larger transparent partial area 70b (and thus beam position 70b' with a larger beam width), the light transmitted through the aperture unit 70 would not only (essentially) hit the micro-mirror element 12 but also the six neighboring micro-mirror elements 12', 12". Since the micro-mirror elements 12, 12', 12" are generally tilted differently, the light deflected by the micro-mirror elements 12, 12', 12" would be imaged in seven different spatial directions. The adjustable aperture unit 70 determines the position and size of the transparent partial aperture area 70b, i.e.the beam position 70b' and beam direction of the transmitted light are adjusted and reduced in size such that the light is (essentially) only deflected by the central micro-mirror element 12.

[0126] It is also possible for a physical pixel to generate multiple virtual pixels by rapidly adjusting the position of the transparent partial aperture area 70b and thus the beam position 70b'. This corresponds to a time-multiplexing method. For example, in the situation shown, the aperture unit 70 could also direct light to the pupil from viewing direction 11** with pupil projection 11* if the angular orientation of the micro-mirror element 12' is suitably adjusted. This is explained by way of example with reference to Fig. 3 above.

[0127] Figure 7b shows a situation in which the observed virtual pixel corresponds to a viewing point 11" that is slightly shifted from the center of the micro-mirror element 12. In the case shown, the beam position 70b' is now selected such that the associated light beam is nevertheless (essentially only) reflected into the eye by the central micro-mirror element 12. The beam position is therefore shifted relative to the viewing direction 11".

[0128] With the same viewing direction, as shown in Fig. 7c, the beam position 70b' could also be selected such that light also falls on the neighboring micro-mirror elements 12', 12". For example, this can be the case if the beam position from Fig. 7a is maintained relative to the viewing direction 11", in contrast to Fig. 7b. If such overlaps of the light with different micro-mirror elements 12, 12', 12" are slight, this can be irrelevant: This is because the neighboring micro-mirror elements 12, 12', 12" have different orientations and generally correspond to only the light from the central micro-mirror element 12 reaching the eye 11. However, the beam width of the light perceived by the user is not only limited by the adjustable aperture unit ("adaptive aperture"), but is also cut off at the edge of the central micro-mirror element 12, which effectively reduces the aperture.The effective beam width corresponding to the hatched portion of the beam surface in beam position 70b' is reduced, which, as a smaller aperture, reduces the resolution. Accordingly, it is usually more advantageous to adjust the beam position relative to viewing direction 11", as shown in Fig. 7b.

[0129] However, there are also cases where this is different. If the transparent partial area 70b and thus its projection 70b' are shifted from position to position in discrete steps, the ideal position of the transparent partial aperture area (shown as an example in Fig. 5b) and thus the ideal beam position cannot be selected for each (physical and / or virtual) pixel. As a technical compromise, the selection of a beam position with a reduced effective beam width, as shown in Fig. 5c, can then be accepted in order to take advantage of the fact that a smaller number of discrete positions of the transparent partial aperture area 70b must be scanned.This smaller number of scan positions has the advantage of a higher achievable brightness for the virtual image, since switching the beam positions 70b' by discretely shifting the partial aperture area 70b requires time during which no light can be transmitted, which reduces the light intensity of the virtual image. However, the brighter the virtual image, the more immersive the perception of the virtual image, since only a sufficiently bright virtual image can prevent the surroundings from shining through the image.

[0130] Figure 7d shows a limiting case corresponding to Fig. 3, in which the viewing direction 11" and thus the observed virtual pixel lies exactly in the middle between two micro-mirror elements 12, 12'. The observed virtual pixel can thus be assigned to two different physical pixels, since the two micro-mirror elements 12, 12' can have different angular orientations, i.e. can be tilted differently. For each physical pixel, respective projections are shown here: for the first physical pixel, whose light is deflected by the first micro-mirror element 12, the projection / beam position 70a', 70b', and for the second physical pixel, whose light is deflected by the second micro-mirror element 12', the projection / beam position 70a", 70b".

[0131] Depending on requirements, in the case shown, one physical pixel can be used for the virtual pixel, or two, possibly even more physical pixels for the one virtual pixel to increase the intensity of this virtual pixel. Fig. 7e shows a case in which the viewing direction 11" and thus the observed virtual pixel lies exactly in the middle between three micro-mirror elements 12, 12', 12". Analogous to Fig. 7d, a third physical pixel can thus additionally be used via the beam position 70b" in the projection 70a" to increase the brightness of the virtual pixel.

[0132] Figure 7f shows the beam positions of many physical pixels on a common micro-mirror element 12. The lights of the different pixels all pass through the aperture unit 70 through the same transparent partial aperture area 70b. However, since the light of each physical pixel leaves the display unit 14 at a different angle, the associated beam positions 70b', 70b", ..70b* on the common micro-mirror element 12 are shifted from one another. For improved brightness of the virtual image, it is advantageous to use several physical pixels simultaneously for a (scan) position of the transparent partial aperture area 70b and thus of the aperture unit 70. This is shown as an example in Fig. 3. However, only pixels should be used (i.e., activated or switched on) that fall entirely onto a common micro-mirror element 12, or at least as shown in Fig.As shown in Fig. 7c, they overlap so significantly with the common micro-mirror element 12 that they are imaged into the pupil 11 as only one virtual pixel. Alternatively or additionally, physical pixels can be used that are far enough apart not to overlap in the virtual image. This is shown as an example in Fig. 4.

[0133] Fig. 8 shows a further exemplary embodiment with an aperture unit arranged on the deflection unit. In contrast to the embodiments shown in Figs. 1 and 2, the aperture unit 70 is arranged near or, as shown in Fig. 8b, within the deflection unit 17. This allows an alternative multiplexing method to be implemented. The multiplexing is implemented essentially near the plane of the micro-mirror elements 12, 12', 12".

[0134] As shown in Fig. 8a, a static first polarizer 90 is inserted into the beam path so that the light striking the micro-mirror elements 12, 12', 12" is fully polarized. Furthermore, a birefringent pixelated switchable (pixelated) liquid crystal element 91 is used to electrically switchably change the polarization, whereby only two states are relevant. With a further static polarizer 92, the individual segments of the segmented liquid crystal 91 can be switched to change the polarization, individual segments 93, 93', 93", and other segments 94 can be switched to maintain polarization, similar to a liquid crystal screen. Thus, light from the display unit 14 falling through the polarization-changing segments 93, 93', 93" is ultimately visible to the user, while light from the display unit 14 falling through the polarization-maintaining segments 94 is ultimately invisible to the user.The liquid crystal element 91 with the second polarization element 92 thus defines the transparent partial aperture regions 70b and the opaque remaining aperture regions 70c. The segments 93, 93', 93", 94 of the liquid crystal element 91 are sized so that light passing through only strikes one of the micromirror elements 12, 12', 12". Depending on the diameter 41 of the exit aperture, several segments, such as 93, 93', 94, can also be used simultaneously.

[0135] 93" polarization-changing and thus the corresponding partial aperture areas 70b are switched transparent. Since only one polarization filter is placed between eye 10 and the natural environment, eye 10 can see the natural environment 100 regardless of the switching state of liquid crystal element 91, albeit with a 50% reduced intensity, as is known from sunglasses. Depending on the design of the polarization states (linear or circular), it may be necessary to place a static wave plate between the second polarizer 92 and micro-mirror elements 12, 12', 12" so that the reflected light can again transmit the polarization filter 92.

[0136] This is shown in greater detail in Fig. 8b. In the example, the display unit 14 emits light or light rays 161", 162", 163" with s- and p-polarization. In the first polarization unit 90, the light rays 161", 162", 163" are s-polarized. In the transparent partial aperture areas 70b of the aperture unit 70, the polarization of light is changed by the liquid crystal element 92 and maintained in the opaque partial aperture areas 70b of the aperture unit 70. In the present case, the light rays 161", 162" are p-polarized and can thus pass through the aperture unit 70 to the micro-mirror elements 12, 12'. The still s-polarized light beam 163", however, is absorbed by the second polarization element 92 and cannot pass through the aperture unit 70. The light beams 161", 162" are reflected by the micro-mirror element 12 and are visible as light beams 161, 162 to the eye 10 and thus to the user, just like the ambient light orthe ambient light rays 100a, 100b.

[0137] Figure 8c shows an embodiment without the second polarization element 92, in which the aperture unit 70 with the liquid crystal element 91 and the first polarization element 90 is arranged close to, here in the deflection unit 17. The liquid crystal element 91 is designed in this case as a switchable λ / 4 plate and thus reverses the polarization of circularly polarized light.

[0138] Light rays 161", 162", which are emitted by the display unit 14 as p+s polarized light, thus first pass through the first polarization element 90 and the liquid crystal element 91 before being deflected by the micro-mirror elements 12, 12'. The light rays 161", 162" are initially linearly polarized, here s-polarized, by the first polarization element 90. A light ray 161", which passes through a transparent partial aperture region 70b, is converted into light with a circular polarization, here I-polarized light. A light ray 162", which passes through an opaque residual aperture region 70c, is converted into light with a different circular polarization, here r-polarized light.

[0139] Upon reflection from the micro-mirror elements 12, 12', the circular polarization is reversed. This results in only the light 161" from the display unit 14, which has passed through the transparent partial aperture area 70b, being transmitted through the polarization element 90 and thus being visible. Light 162", which only passes through the opaque remaining aperture area 70c, has the incorrect polarization for the polarization element 90 and is absorbed by it. Light from surrounding positions 100a, 100b is not visibly influenced by the liquid crystal element 91; only the overall intensity is reduced by the polarization element 90, similar to sunglasses. Fig. 9 shows a plan view of one plane of an exemplary embodiment of a spectacle display system with an additional focusing unit and, in this case, also vision correction.The additional focusing unit 13" as adaptive optics is adjusted in its focus by a control unit 110. For example, the focus of the virtual image can be set either to infinity (beam path / light beam 112) or to finite (beam path / light beam 111). This solves the vergence accommodation problem. If the focus can be adjusted faster than a frame rate, different focal planes can even be set within a virtual image.

[0140] With an additional lens element 13'" between the deflection unit 17 and the environment 100, a visual acuity correction can be integrated without great effort. Its properties are then to be taken into account accordingly by the control unit 110.

[0141] Figure 10 shows another embodiment of a glasses display system in a glare situation. Another person 143 can look into the display unit 14 with their eyes 10" (the optics 13 is formed here as part of the display unit 14). Thus, there is a risk that person 143 will be dazzled. Since the glasses display system 1 uses cameras 142, 142', for example, to determine their orientation in space, these cameras 142, 142' and / or other sensors such as the eye tracking device 15 can measure the eye positions 10, 10' of the user. This also allows the calculation of an angular range 145 in which emitted light dazzles the opposite person 143. The control of the display unit 14 can thus be informed that there is a risk of dazzling in the angular range 145 and, for example, no content will be displayed in this area or only with reduced intensity.

[0142] Fig. 11 shows another exemplary embodiment of a spectacle display system. As can be seen from Fig. 11a, the spectacle display system 1 in this example has a deflection unit 17 with a plurality of micro-mirror units 12, 12', 12'', which are arranged over a large area in a field of view corresponding to that of conventional spectacles. Fig. 11b shows an interior view of the deflection unit 17 with the many micro-mirror units 12, 12', 12". Adjacent micro-mirror units 12, 12' are shown here as examples, which partially overlap. In the example shown, the micro-mirror units 12, 12', 12" are arranged offset in the y-direction and are also of different sizes. Micro-mirror unit 12" has a larger reflection surface than micro-mirror unit 12', and micro-mirror unit 12' has a larger reflection surface than micro-mirror unit 12.

[0143] Fig. 12 shows a further schematic illustration of an exemplary embodiment of a spectacle display system. As in the previously described embodiments, light beams 161", 162" generated in a display unit 14 are redirected into the respective eye 10 via micro-mirror elements 12, 12", 12'". Each light beam 161, 162 redirected into the eye 10 corresponds to a pixel of the virtual (AR) image. The eye 10 can thus perceive an angular range of the virtual image associated with the respective micro-mirror element 12, 12", 12'" via each of the micro-mirror elements 12, 12", 12'".

[0144] Furthermore, the spectacle display system 1, as is known, comprises the display unit 14 and the adjustable aperture unit 70, as well as an optic 13 between the adjustable aperture unit 70 and the display unit 14, and in this exemplary embodiment also a projector optic 130 between the adjustable aperture unit 70 and the deflection unit 17. For better clarity of the illustration, the display unit 14 and the adjustable aperture unit 70, the optic 13 and the projector optic 130 are shown here with a common optical axis O enlarged at an arbitrary position in Fig. 12.

[0145] The light rays 161", 162" reflected by the micro-mirror elements 12, 12", 12'" reach the eye 10 from the display unit 14 through a projector optics 130 (shown schematically in Fig. 12 with three indicated lenses). This projector optics 130 images at least substantially onto a sharpness or focal plane Fl, on which the display unit 14 or the display of the display unit 14 is not arranged. There, the angular ranges assigned to the respective micro-mirror elements 12, 12", 12'" would lead to overlapping areas, as shown in more detail in Figs. 13a-13e. There, five areas 120a-120e are shown in the focal plane Fl by way of example, each of which overlaps with its nearest neighbors. In the case of overlapping areas, a physical pixel of the display unit 14 is thus visible in the eye 10 via more than one micro-mirror element 12, 12", 12"'.

[0146] The projector optics 130 is arranged and / or configured within the glasses display system 1 such that, according to the imaging formula 7 = - + 7, a further f 9 b

[0147] The focal plane provides a sharp image of the micro-mirror elements 12, 12", 12'". In this further focal plane, the adjustable aperture unit 70 is arranged. The adjustable aperture unit 70 is advantageously designed such that a transparent and opaque switchable pixel of the adjustable aperture unit 70 corresponds at least substantially to the imaged area of ​​the respectively assigned micro-mirror element 12, 12", 12'".

[0148] The optics 13 (here arranged between the adjustable aperture unit 70 and the display unit 14) are advantageously designed to image the physical pixels of the display unit 14 such that the light beam generated by the respective physical pixel can be perceived in the eye 10 with the desired sharpness. Accordingly, the optics 13 can also include or be the above-mentioned additional focusing unit 13". Alternatively, the optics 13 can also be arranged in the beam path between the adjustable aperture unit 70 and the projector optics 130. For example, the adjustable aperture unit 70 can also be arranged in the beam path between the display unit 14 and an optics 13 embodied as a microlens array, as explained below.

[0149] As illustrated in the schematic diagrams of Fig. 13, the multiplexing approach in the shown setup can achieve a wide range of different degrees of redundancy in the use of the physical pixels by using different optics.

[0150] Fig. 13a illustrates an embodiment in which one and the same area of ​​the display of the display unit 14 corresponds to all areas 120a-120e of the virtual image, each of which is imaged onto a single micro-mirror element. Accordingly, in pure time-multiplexing, at a predetermined point in time, for example, an image content 140a is assigned to area 120a of the virtual image via a transparently switched aperture pixel 70-1. At this point in time, the other aperture pixels 70-2 to 70-5 are then opaque. At a subsequent point in time, for example, image content 140b, which at the subsequent point in time occupies the same area of ​​the display of the display unit 14 as the image content 140a previously, can be assigned to the area 120b of the virtual image via a transparently switched aperture pixel 70-2, ie displayed there, wherein the remaining aperture pixels 70-1 and 70-3 to 70-5 are opaque, etc. pp. The aperture pixels 70-1,..70-5 can correspond to the above-mentioned segments 93, 93', 93", 94 and / or vice versa. Aperture pixels 70-1,.. 70-5 and segments 93, 93', 93", 94 can also correspond to the switchable partial aperture areas 70a.

[0151] Alternatively, the optics 13 can also map mutually shifted and / or scaled (then partial) regions of the display unit 14 onto the respective regions 120a-120e of the virtual image. This is illustrated in Fig. 13b for shifted image contents 140a-140e. Another possibility is to specify groups of aperture pixels 70-1,... 70-5 that share a sub-region of the display area of ​​the display unit 14. This is illustrated in Fig. 13c and has the advantage that several aperture pixels 70-1,... 70-5, namely one aperture pixel 70-1,... 70-5 per group, can be open simultaneously without cross-fading occurring. Due to the resulting parallel use of the aperture unit 70, a sufficiently bright virtual image can be generated with a lower light intensity of the display unit 14 than would be the case with pure time-multiplexing of the aperture pixels 70-1, .. 70-5.

[0152] Finally, in the case shown in Fig. 13d, no multiplexing is required. The optics 13 comprises, or in this case is, a microlens arrangement ("microlens array") with a plurality of microlens elements arranged parallel in the beam path. The microlens elements 13a-13e are designed to image spatially disjointly displayed image contents 140a-140e on the display of the display unit 14. This allows all image contents to be displayed simultaneously without multiplexing. Displays with low maximum brightness can also be used as display technology, e.g., OLED technology, which cannot achieve such high intensities for a short time as is the case, for example, with pLED displays.

[0153] Finally, Fig. 13e illustrates the case of an adjustable aperture unit 70 integrated into the optics 13. In this case, the adjustable aperture unit 70 is arranged in the further focal plane, like the optics 13.

Claims

Claims 1. Glasses display system (1) for displaying a virtual image in a field of view of a user, with - a display unit (14) for emitting a light (163", 161", 162") as computer-generated image information in a radiation direction; - a deflection unit (17) for deflecting the light (163", 161", 162") emitted by the display unit (14) as computer-generated image information into an eye (10) of the user, with a plurality of micro-mirror elements (12, 12', 12") each tiltable in a support structure, which each have at least one reflection surface (25) for deflecting the light (163", 161", 162") emitted by the display unit (14) as computer-generated image information; characterized by - an aperture unit (70) arranged in an optical path of the light (163", 161", 162") between the display unit (14) and the tiltable micro-mirror elements (12, 12', 12"), which aperture unit is adjustable by means of a control signal and is designed to adjust at least one beam position (70b', 70b", 70b*) for the light deflected at the reflection surfaces (25) of the tiltable micro-mirror elements (12, 12', 12") in accordance with the control signal.

2. Spectacle display system (1) according to the preceding claim, characterized in that the adjustable aperture unit is arranged in an optical path from the display unit (14) to the deflection unit (17) between an optic (13, 130), in particular a projector optic (130) and / or an optic (13) designed as a microlens arrangement, of the spectacle display system (1) and the display unit (14).

3. Spectacle display system (1) according to one of the preceding claims, characterized in that the adjustable aperture unit (70) is designed to adjust the at least one beam position (70b', 70b", 70b*) by adjusting at least one position of a respective transparent partial aperture area (70b) within an overall aperture area (70a) that can be made transparent by the control signal.

4. Spectacle display system (1) according to one of the preceding claims, characterized in that the adjustable aperture unit (70) is designed to adapt, in addition to the beam position (70b', 70b", 70b*), a beam width associated with the beam position (70b', 70b", 70b*) for the light deflected at the reflection surfaces (25) of the tiltable micro-mirror elements (12, 12', 12") according to the control signal.

5. Spectacle display system (1) according to one of the preceding claims, characterized in that the adjustable aperture unit (70) is designed to adjust the beam width such that it is smaller than the diameter (40) of the reflection surface (25) or the reflection surfaces (25) of the respective illuminated micro-mirror elements.

6. Spectacle display system (1) according to one of the preceding claims, characterized in that the adjustable aperture unit (70) is designed to adjust the beam position (70b', 70b", 70b*) and the beam width for the light in such a way that a large part of the light (163", 161", 162") transmitted through the adjustable aperture unit (70) illuminates the reflection surface (25) of exactly one micro-mirror element (12, 12', 12"), in particular in combination with a partial shutdown of the display unit.

7. Glasses display system (1) according to one of the preceding claims, characterized in that - a refresh rate is specified for the computer-generated image information; and - the aperture unit (70) is designed to adjust the beam width and / or beam position (70b', 70b", 70b*) several times within the time period specified for an image according to the refresh rate.

8. Spectacle display system (1) according to the preceding claim, characterized in that the aperture unit (70) is designed to adapt the beam position (70b', 70b", 70b*) to at least three, in particular at least 7, preferably at least 10 and particularly preferably at least 200 different beam positions within the time period predetermined according to the refresh rate for an image.

9. Spectacle display system (1) according to one of the preceding claims, characterized in that the aperture unit (70) is designed to simultaneously switch transparent a plurality of different, preferably 3 or more different, in particular non-adjacent, partial aperture regions (70b) within a transparent and / or opaque switchable overall aperture region (70a) of the aperture unit (70), wherein the different simultaneously switchable partial aperture regions (70b) belong to different groups of partial aperture regions (70b), and the partial aperture regions (70b) of the different groups of partial aperture regions (70b) are assigned to different physical pixels of the display unit (14).

10. Spectacle display system (1) according to one of the preceding claims, characterized in that the aperture unit (70) is designed to adjust the beam width and / or beam position (70b', 70b", 70b*) with a frequency of at least 100 Hz, preferably at least 1000 Hz, particularly preferably at least 20 kHz.

11. Spectacle display system (1) according to one of the preceding claims, characterized in that the aperture unit (70) comprises a pixelated liquid crystal element (91) or a such is.

12. Glasses display system (1) according to the preceding claim, characterized in that - the pixelated liquid crystal element (91) is or comprises a switchable wave plate; - the aperture unit (70) comprises, in addition to the liquid crystal element, a first static polarization element (90) which is transparent to a first polarization and which is arranged in the optical path between the display element (14) and the pixelated liquid crystal element (91), preferably on the display unit (14) or on the deflection unit (17); and - in particular, the aperture unit (70) comprises, in addition to the liquid crystal element, a first and a second static polarization element (92), which is permeable to a second polarization different from the first polarization and which is arranged between the pixelated liquid crystal element (91) and the micro-mirror elements (12, 12', 12"), preferably on the deflection unit (17); and - the adjustable aperture unit (70) is designed to adapt the beam position (70b', 70b", 70b*) by adapting the polarization conversion property of the overall aperture area (70a) either to convert the polarization in the transparent partial area(s) (70b) in combination with maintaining the polarization in the remaining area of the overall aperture area (70a) different from the transparent partial area(s) (70b), or vice versa.

13. Glasses display system (1) according to one of the preceding claims, characterized by - a control unit which is designed to control the adjustable aperture unit (70) by means of the control signal and the display unit (14) with a further control signal according to a time-multiplexing, in which at least two virtual pixels of the virtual image are assigned to one physical pixel of the display unit (14).

14. Spectacle display system (1) according to one of the preceding claims, characterized by an additional focusing unit, in particular with or consisting of an electrically adjustable liquid-controlled lens, in or on the display unit (14), which is designed to shift a focal plane for the light emitted by the display unit (14) according to an additional control signal.

15. Spectacle display system (1) according to one of the preceding claims, characterized in that the display unit (14) is designed to adapt, for the beam position (70b', 70b", 70b*) adjusted by the diaphragm unit (70), in each case also an intensity of the light emitted towards the respective beam position (70b', 70b", 70b*), in particular such that a light flux of the light reaching different beam positions (70b', 70b", 70b*) one after the other or simultaneously is equalized.

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