Glasses display system for displaying a virtual image in a user's field of vision using invisible micro-mirror elements.

Abstract

The disclosure relates to a spectacle display system (1) for displaying a virtual image in a user's field of vision, comprising a display unit (14) for emitting light (163", 161", 162") as computer-generated image information in a direction of emission and 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, comprising a plurality of micro-mirror elements (12, 12', 12") which are each tiltable in a carrier structure (200) and 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 the micro-mirror elements (12, 12', 12") and the support structure (200) are arranged in a liquid-filled sealed housing element (17a) of the deflection unit (17) to provide an enhanced immersion spectacle display system (1).

Description

Scope of the invention The disclosure 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 direction of emission and a deflection unit for deflecting the light emitted by the display unit as computer-generated image information into the user's eye, comprising a plurality of micro-mirror elements, each tiltable in a carrier structure, which each have a reflective surface for deflecting the light emitted by the display unit as computer-generated image information. background Eyeglass display systems for displaying a virtual image in a user's field of vision, commonly known as "augmented reality glasses" or "AR glasses," are able to overlay virtual objects in the form of virtual images onto the user's natural environment, thus virtually supplementing their field of vision. By displaying stereoscopic images, these virtual objects can be freely positioned in space. For this reason, it is advantageous to enable the largest possible virtually supplemented field of view and a display with high (angular) resolution in order to create an immersive feeling through the constant visibility and spatially consistent positioning of the virtual objects—namely, the feeling that the virtual objects are physical objects. The weight of such glasses also contributes to this immersive feeling, as it can create an unnatural sensation for the user, especially during head movements.The vergence-accommodation problem is also a well-known effect that is detrimental to the immersive feeling, or immersion. The vergence accommodation problem exists in all 3D displays that present 3D objects using two stereoscopic images. The 3D information, i.e., the object's distance from the eye, is given by the shifted stereoscopic images. This distance conflicts with the distance at which the eye focuses 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 stereoscopic image does not match the focus distance of the real environment, both scenes—the real and the virtual—cannot be viewed simultaneously, even though they are displayed in the same spatially fixed location within the environment. According to the current state of the art, various optical methods are known for projecting a virtual image onto the natural environment within the field of vision. However, it remains a technically unsolved problem to make the necessary optics sufficiently small to achieve a form factor and weight comparable to normal eyeglasses. Glasses that are too large represent a technical limitation for potential applications, as, for example, one would not accept a large product on one's 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 2020 206 392 A1 and DE 10 2023 101 777 A1. Patent US 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 projected in the peripheral field of vision. For this purpose, the eye's gaze direction is measured using eye-tracking sensors, and the projection optics are adjusted accordingly. AR glasses with transmissive beam splitters in the user's field of vision are explained in DE 10 2021 206 209 B3. Publication US 2020 0186761 A1 presents AR glasses that allow the focal length of the AR optics to be adjusted to display objects at different distances. This reveals a technical solution to the vergence accommodation problem. US 2020 0186761 A1 also includes an eye-tracking module to measure vergence eye parameters. Furthermore, it is proposed that these measurements be used to track the optics in relation to the eye, thus enabling eye-tracking for different eye positions. DE 60 2004 006 592 T2 discloses a microactuator for micromirrors with a dielectric emulsion. US 2021 0 356 646 A1 discloses micromirrors arranged in a liquid-filled cavity of a waveguide. The technical challenge therefore arises to provide a glasses display system with improved immersion, in particular with minimized weight and the largest possible virtually augmentable field of view, as well as the ability to address problems typical for AR glasses such as the vergence accommodation problem and / or the problem of visual acuity correction. overview This problem is solved by the subject matter of the independent claim. Advantageous embodiments arise from the dependent claims, the description, and the figures. One aspect concerns a glasses display system for showing a virtual image in a user's field of vision. This system includes a display unit that emits light as computer-generated image information in a specific direction, and a deflection unit that redirects the light emitted by the display unit into the user's eye. The light is emitted forward into the user's field of vision (forward, thus radiating the light into the field of vision). The deflection unit, equipped with at least the micro-mirror elements mentioned below, is positioned in the user's field of vision (in front of the user's eye(s)) and serves to redirect the light back (backward) into the user's eye(s). The deflection unit comprises numerous tiltable micro-mirror elements, each arranged within a support structure. These elements redirect the light emitted by the display unit as computer-generated image information into the user's eye. Each reflective surface is transparent to ambient light emanating from the user's field of vision. Therefore, the reflective surfaces can be considered semi-transparent mirrors. A multitude of micromirrors can, for example, be understood to mean at least 20, at least one hundred, or at least one thousand micromirrors. As is typical for micromirrors, the reflective surfaces are small, for example, <100 mm² or <20 mm². Since the micromirrors are movably mounted in the support structure, the reflective surfaces can be aligned in two dimensions. This allows the light emitted by the display unit to be redirected into the eye or pupil, even for different orientations and / or positions of the eye.Since the deflection unit, at least partially (i.e., partially or completely), and especially with its micro-mirror elements, is positioned in the optical path of ambient light from the user's field of vision to the user's eye, the virtual image corresponding to the computer-generated image information can be superimposed on real objects in the user's field of vision. This is because the micro-mirror elements (as required in AR glasses) are at least partially transparent to ambient light. For a more immersive experience with the largest possible, artifact-free virtual images, the deflection unit and / or the display unit is controlled depending on the orientation of the eye(s), for example, by the control unit described below. Advantageously, all micro-mirror elements (especially always and / or predominantly) are oriented at such an angle that only light from the display unit is directed into the user's eye. This prevents any light source positioned elsewhere from causing visible reflections in the eye. This avoids distracting light reflections and ghost images. This is particularly beneficial in outdoor applications where the sun, as a very bright light source, can cause otherwise unpleasant glare. A further resulting advantage is that a high reflectivity, such as a semi-transparent coating, can be chosen for the reflective surfaces of the micro-mirror elements, as even with high reflectivity, unwanted light reflections in the eye are not amplified. The display unit can generate the light by comprising one or more preferably planar screen elements ("displays") or one or more (laser) projector elements. In particular, the display unit can be a stereo display unit capable of generating a virtual stereo image in the user's field of vision. For this purpose, the stereo display unit can comprise two screen elements or two (laser) projector elements, each assigned to one of the user's eyes. For example, the screen elements or (laser) projector elements can each be arranged on a temple unit of the eyeglass display system, positioned laterally on the user. In one embodiment, the micromirror elements and the support structure can be arranged in a sealed housing element of the deflection unit filled with a liquid. The housing element can be positioned in front of the user's eyes, similar to the lenses of conventional eyeglasses. Accordingly, the liquid, the micromirror elements, and the support structure are arranged within an interior space of the housing element such that the micromirror elements and the support structure are surrounded by the liquid. The housing element is oil- and / or water-resistant and made of a material that is transparent (at least substantially) to ambient light and the light from the display unit, as is the case with conventional eyeglass lenses. The micromirror elements and the support structure are also advantageously made of a transparent material, as explained again below. The liquid bath containing the micromirror elements and support structure has a damping effect, suppressing vibrations and thus unwanted small, rapid changes in the angular orientation of the reflective surfaces. This is advantageous because the eye makes abrupt movements of up to 1000° per second and then rests. Furthermore, the liquid reduces the refractive index difference at the material interface, i.e., the surface between the liquid and the micromirror or support structure. This reduces Fresnel reflections and other refractive effects. Both of these reductions in reflections and effects decrease the visibility of the elements or structures in the liquid bath, similar to what is observed with glass components immersed in water.This avoids artifacts in the user's field of vision that would detract from the immersive experience and makes the use of the micro-mirror element arrangement ("micro-mirror array") directly in front of the user's eyes, within their field of vision, possible in the first place. The micro-mirror array is what enables the large-area virtual augmentation of the field of vision with higher (angular) resolution for the virtual image and is therefore a prerequisite for an immersive glasses display system with dimensions similar to those of standard eyeglasses. In a further embodiment, the micro-mirror elements and / or the support structure and / or other components surrounded by or adjacent to the liquid (such as an interior-facing side of the housing element) are each (at least substantially) transparent to the ambient light from the user's field of vision, as described above for the housing element. The micro-mirror elements and / or the support structure and / or other components are accordingly made of or with a respective transparent material having a first refractive index. In particular, the housing element and / or the micro-mirror elements and / or the support structure and / or the other components can be made of the same material, which facilitates the matching of their optical properties. The liquid for ambient light is also (at least essentially) transparent and has a second refractive index adapted to the first refractive index to minimize 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 specified limit of, for example, 0.005 over a given wavelength range of, for example, 400 nm to 700 nm and / or a given temperature range of, for example, 0° to 30°. The liquid can also be optimized for one or more sub-ranges of the respective ranges, for example, exhibiting a second refractive index particularly similar to the first in the wavelength range of 540 nm ± 30 nm and / or in the temperature range of 21° ± 2°. In this sub-area, a smaller maximum deviation limit can be specified, for example, 0.002. Such liquids, "refractive index matching liquids," are commercially available with the desired properties. Accordingly, it can be advantageous to actively control the temperature of the micromirror array, i.e., to measure it and adjust it to a target temperature or temperature range by heating or cooling. Therefore, a temperature control device for the liquid can be provided. This device can include a sensor unit for measuring the liquid temperature and a temperature control unit for adjusting the liquid temperature to a predetermined value, i.e., depending on the measured value and the predetermined temperature, either 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 in the wavelength range and / or angular range and / or temperature range, remains 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. Therefore, the micro-mirror elements can be arranged over a large area in front of the user's eyes without disturbing their perception of the surroundings and thus the virtual image, thereby significantly improving the immersive experience when using the glasses display system. In another embodiment, the micro-mirror elements are mechanically coupled to a common actuator element, in particular by means of a two-dimensional guide matrix structure. The guide matrix structure can be mechanically scanned by the support structure to achieve individual tilts (angular alignments) of the micro-mirror elements. Alternatively, each micro-mirror element can be coupled to an individual actuator element. In both cases, the angular alignment of the micro-mirror elements can be controlled via the common actuator element or the individual actuator elements according to a stored predefined setpoint, either in the form of a mechanical guide or, for example, a lookup table.The common or individual actuator elements can be configured to move at least some, and in particular most and / or all, of the micro-mirror elements independently and / or non-linearly. The angular orientations of the reflective surfaces can therefore be individually and / or non-linearly defined, for example, by the guide matrix structure and / or an actuator control setting. This individual and / or non-linear adjustment ensures that the redirected light always reaches the eye, resulting in larger, coherent virtual images. The common actuator element reduces the number of components required for the deflection unit that are located within the user's field of vision. This contributes to the reduced visibility of the structures within the user's field of vision, thus enhancing the immersive experience. The micro-mirror elements can each be equipped with an individual angle sensor to measure their respective angular orientation. This allows for a comparison of the target and actual angular orientation of the respective reflective surface, thus helping to reduce unwanted shifts of virtual pixels in the virtual image. With such angle sensors, small deviations from the target orientation on the order of 1 / 120° can be compensated for by means of a corresponding control signal for the actuator element(s) (and thus via software). In one embodiment, the reflective surfaces are hexagonal, and in particular, each micro-mirror element has a coating on its reflective surface. The reflective surfaces can have a diameter, in particular an overall height and / or width, of at least 1 mm, in particular at least 2 mm, and / or at most 10 mm, in particular at most 4 mm. The hexagonal shape allows for a particularly dense arrangement of the micro-mirror elements and a correspondingly high-resolution, two-dimensional display of the virtual image. Due to the reduced visibility of the micro-mirror elements and connected components, this is achieved with minimal artifacts without diminishing the immersive experience. If polarized light is used for the virtual image, it is advantageous to select a coating with increased reflectivity for the polarization used.Because when viewing the natural environment through the partially mirrored reflective surfaces, both polarization states are present in the natural ambient light, the effective transparency of the micromirror coating is therefore higher. The coating also allows for the definition of desired reflection properties without negatively affecting the visibility of the micromirror elements, which would otherwise be determined (for example, by the geometry of the micromirror elements). In a further embodiment, the reflective surfaces are provided to have at least partially different sizes, i.e., different widths and / or different heights. In particular, one or more reflective surfaces located closer to the user's central line of sight in a forward-facing neutral eye position can be smaller than one or more reflective surfaces located further away from the user's central line of sight. For the virtual image to be visible to the eye, the light from an output aperture ("exit aperture") of the display unit must be deflected into the pupil of the eye via the respective micromirror element. This establishes a relationship between the maximum size of the respective micromirror elements and the diameter of the output aperture of the display unit.In an advantageous embodiment, the respective reflective surfaces can be chosen to be as close as possible to, or equal to, the maximum size. The maximum size is smaller near the central viewing axis than further away. This approach takes advantage of the fact that this results in fewer mirror transitions where each virtual sub-image, visible via a single micromirror element, must connect to the adjacent sub-image. This sub-image must be calculated for each transition to avoid artifacts. A smaller number of micromirror elements thus reduces this computational effort. Furthermore, diffraction effects are minimized, which occur when the beam of light is clipped at the edge of each micromirror element if it only partially strikes the micromirror.The design with fewer micro-mirror elements thus minimizes these diffraction artifacts and enables an improved display of a virtual image and therefore improved immersion. In another embodiment, the reflective surfaces are concave. Alternatively or additionally, the reflective surfaces can be flat. The concave reflective surfaces enable particularly high light efficiency. This allows the light from only one physical pixel of the display unit to be imaged onto a specific micromirror, and from there it is precisely directed to the location in the user's eye intended for the virtual image. Accordingly, multiplexing is not required in this case. The concave reflective surfaces can also be designed to focus directly onto the display unit. This eliminates the need for additional optical elements, but all micromirror elements simultaneously image the display unit.As a result, a multiplexing method must be used to uniquely map pixel information (the light of a physical pixel of the display unit) in a viewing direction. Planar reflective surfaces are particularly advantageous when an additional focusing unit is provided in the optical path between the display unit and the deflection unit, for example, to resolve the vergence accommodation problem and / or to compensate for a user's visual impairment. This additional focusing unit allows the focus of the virtual image to always be adjusted to the current viewing direction. Information about the eye's orientation ("eye tracking"), as described below, can be used for this purpose. Preferably, the focus is changed uniformly for the entire virtual image, for example, by using an electrically adjustable liquid-controlled lens. However, other optical approaches are also possible, such as stacking multiple transparent displays.Planar reflective surfaces allow for the display of any focal distance without resulting imaging errors – other well-known beam splitter technologies, such as the so-called “waveguides”, must, however, be designed for a fixed, predetermined focal distance. 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), independent of the resolution of the vergence accommodation problem. In this case, an additional lens element must be placed in the optical path of the ambient light from the field of view to the eye, between the environment and the redirecting unit. For example, the user could wear their conventional glasses for vision correction over the AR glasses or use a suitable attachment. Further lens elements between the display unit and the redirecting unit allow for even finer vision correction. In one embodiment, the support structure and / or the micro-mirror elements and / or other components surrounded by the liquid are shaped such that the ambient light from the user's field of vision passes through interfaces between transparent material and liquid and / or between liquid and transparent material at least predominantly, for example from a predetermined sub-area of ​​the field of vision, at small angles, and in particular at least predominantly at angles of less than 45°. The ambient light should thus strike the aforementioned interfaces at a very shallow angle at as few points as possible, ideally nowhere, and at a steep angle at as many points as possible, ideally everywhere.Since ambient light from different areas of the field of vision strikes the aforementioned interfaces at different angles, particularly important parts can be selected for the given sub-area, for example, the area around the user's central line of sight. This allows for the selection of a geometry for the support structure and / or micro-mirror elements and / or other components that minimizes perceptible refraction and diffraction effects, thus further reducing the visibility of these components and their effects. In a further embodiment, the reflective surfaces of at least some micro-mirror elements, and in particular most micro-mirror elements, overlap in an orthogonal projection onto a plane perpendicular to the user's central line of sight. This applies when the micro-mirror elements or the reflective surfaces are oriented parallel (or, in the case of physical contact, as parallel as possible). The overlapping micro-mirror elements reduce diffraction effects and increase resolution. Preferably, the micro-mirror elements overlap only in areas where, during intended use (for example, within the range of angular orientations defined by the actuator element(s)), they are tilted sufficiently to prevent physical contact during operation.In particular, it can be provided that the reflective surfaces do not overlap in areas where, during intended use, they are perpendicular to the central viewing axis at least at one time. It can be designed so that the reflective surfaces of the micromirror elements overlap in the vicinity of the user's central line of sight in orthogonal projection. This design is advantageous because, in typical positions of the display unit on the side of a temple of the glasses, the micromirrors visible when looking straight ahead are tilted sufficiently to allow for mechanical overlap. Towards the side of the temple, there is an area where no overlap is possible. Thus, in the straight-ahead viewing area, a higher resolution can be achieved due to the overlap and the resulting reduction in diffraction effects, which is advantageous for use in AR glasses.In addition, people tend to turn their heads to look to the side in the medium term, in combination with looking in the central line of sight ("straight ahead"), rather than looking sideways with their eyes turned, so the increased resolution especially in the area of ​​the central line of sight ("straight ahead") improves immersion. In one embodiment, the micro-mirror elements are arranged in a one- or two-dimensionally curved surface. The curved surface can be defined as a two-dimensional manifold in three-dimensional space. The micro-mirror elements are thus arranged at least partially offset from one another in the direction of the central viewing axis. This is particularly advantageous in conjunction with the overlapping micro-mirror elements described above, as it allows overlap (with the described advantages) to be achieved in more areas, i.e., for more micro-mirror elements. In a further embodiment, the housing element is provided with an anti-reflective coating on one side facing the display unit, in particular an anti-reflective coating with locally varying anti-reflective properties. Since the light from the display unit is typically coupled laterally from the temple side into the deflecting unit and then reflected by the micro-mirror elements, reflection also occurs at the interface between the air and the transparent material of the housing element. This reflection is visible to the eye at different positions depending on the pupil position and is undesirable, but can be sufficiently reduced by the anti-reflective coating. This also reduces artifacts and thus increases immersion. In an advantageous configuration, the display unit can emit polarized light, particularly linearly polarized light, so that unwanted reflections can be further reduced by means of a specially designed anti-reflective coating. It is also advantageous to align the polarization direction accordingly for minimal reflection. If the light emission direction relative to the side of the housing element facing the display unit is chosen as close as possible to Brewster's angle, depending on the overall geometry of the spectacle-display system, unwanted reflections can be almost completely avoided. Anti-reflective coatings are also typically applied to conventional spectacle lenses to ensure clear vision of the natural environment.For the spectacle display system, it is therefore advantageous to choose a coating that enables both low reflection during normal viewing and low reflection of the light emitted by the display unit. Since the reflection of the light emitted by the display unit is only visible in a small area, locally variable coatings are advantageous. These eliminate the reflection of the light emitted by the display unit in the area of ​​the virtually augmented field of vision and significantly improve visibility in the remaining area. In one embodiment, the spectacle display system includes an eye-tracking device for determining the user's eye orientation and a control unit for controlling the redirection unit based on the eye orientation determination. This allows the light to be directed precisely into the eye's pupil, increasing light efficiency and avoiding undesirable effects such as "eye glow," where reflections of the redirected light appear in the user's eye. Due to the improved energy efficiency, the weight of components such as a battery and the size of the display unit, for example, can be reduced, further enhancing immersion. The control unit may also be configured to control the display unit according to an assignment rule stored within the control unit. This assignment rule may specify a mapping 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 assigned to different physical pixels for different eye orientations (and therefore at different times). This is because any movement of the micro-mirror elements always changes the mapping of physical pixels of the display unit to virtual pixels of the virtual image, and this changes differently for each pixel combination.This non-linear change is compensated for by the assignment rule, ensuring that the virtual pixels within the virtual image maintain their desired position. This improves image quality and enables particularly large virtual images. In one embodiment, an aperture unit, adjustable by means of a control signal, can be arranged in an optical path of the light between the display unit and the tiltable micro-mirror elements. The adjustable aperture unit is configured to adapt at least one beam position and / or at least one beam distance associated with the respective beam position for the light deflected at the reflective surfaces of the tiltable micro-mirror elements according to the control signal.The adjustable aperture unit allows the location of the light striking the deflection unit to be determined via the adjustable beam position, thus determining which micromirror elements the light hits, and / or the size of an area on the deflection unit upon which the light hits via the adjustable beam distance. This allows certain micromirror elements near the beam position to be excluded from illumination by the light, for example, micromirror elements that would only be partially illuminated with light at a larger beam distance (as explained in more detail below). This has the effect that, with the control signal and the adjustable aperture unit (which can also be called an adaptive aperture), an output aperture ("exit aperture") of the display unit can be dynamically set, i.e., varying over time, by a control signal. In general (i.e., when considering the display without an aperture unit), the exit aperture of the display unit is visible to the eye as a reflection across each micromirror element. If the exit aperture is very large, any necessary multiplexing becomes more complex, and the weight of the AR glasses increases without any added benefit. Therefore, when designing the exit aperture (i.e., its diameter), it is 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, and the virtually augmented field of view is relatively small. The exit aperture of the display unit therefore requires a certain minimum size to enable a light path from the display unit to the micromirror element and from the micromirror element to the eye for all AR viewing angles, i.e., for the largest possible virtually augmentable field of view. Pixel image information is thus projected as a beam of light with the diameter of the display unit's exit aperture onto the deflection unit, onto the micromirror elements (the "micromirror array" as a whole). A typical diameter for an exit aperture is, for example, 8 mm. A typical diameter for micromirror elements or their reflective surfaces is 2-4 mm. Thus, the beam of light from a pixel image falls on several adjacent micromirror elements simultaneously.Since each micromirror element is ideally aligned, depending on the eye's current orientation, so that the central line of sight from the pupil is projected onto the center of the display unit's exit aperture, it is possible for light from a pixel image, falling simultaneously on two adjacent micromirror elements, to be perceived by the eye at the same time. However, because adjacent micromirror elements are oriented differently, the same pixel image information is perceived from two differently reflected directions, resulting in one or more virtual ghost images. The adjustable aperture unit projects only a cropped beam of light 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. It is therefore advantageous to design the adjustable aperture unit such that, for each micromirror element, only viewing directions are provided for the virtual image where the light striking the respective micromirror element covers a larger area than on other, (nearest) neighboring micromirror elements. Extreme viewing directions, which primarily (i.e., at least predominantly) strike an adjacent micromirror element and only very slightly affect the micromirror element being viewed at any given time, for example, just barely grazing it, should accordingly no longer enter the exit aperture of the display unit. Accordingly, a small exit aperture of the display unit can be selected for each micromirror element viewed at a specific multiplexing time point, for example, within a time-division multiplexing process, in order to improve image quality.This is achieved with the adjustable aperture unit. This has the advantage of minimizing diffraction effects during image formation and achieving maximum sharpness of the virtual image. This is because a micromirror element acts as an aperture, deflecting only a small portion of the total beam of light originally emitted by the display unit into the eye. This means that the beam can be clipped if it is only partially reflected. It is known from optics that diffraction increases when the aperture is small. Therefore, it is advantageous to position the beam of light on the micromirror element using the adjustable aperture unit in such a way that it is not, or only minimally, clipped by the micromirror element. In another embodiment, the adjustable aperture unit is designed to adjust the beam position by adjusting at least one position of at least one transparent partial aperture area (i.e., one switched to transparent by means of the control signal) within a total aperture area that can be switched to transparent or opaque by means of the control signal. A remaining area of ​​the total aperture area complementary to the at least one partial area is opaque (i.e., switched to opaque by means of the control signal). Thus, one or more partial aperture areas can be switched to transparency, so that only these partial aperture areas are transparent to light from one or more pixel image information associated with the respective partial aperture area, and other pixel image information does 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 technique. This has the advantage of avoiding or at least reducing crosstalk of pixel image information, which, for example, results in the aforementioned ghosting. Thus, image quality is improved even for large fields of view, and the immersion of the system is enhanced. The described features and combinations of features, including those in the general introduction, as well as the features and combinations of features disclosed in the figure description or the figures themselves, 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 shown and described in the figures, but which can be generated by separately combining the individual features disclosed in the figures, are also part of the invention. Therefore, embodiments and combinations of features that do not include all the features of an originally formulated independent claim are also to be considered disclosed.Furthermore, embodiments and combinations of features that differ from the combinations of features or go beyond those described in the dependencies of the claims are to be considered disclosed. In the context of this disclosure, "transverse / along" can be understood as "at least substantially perpendicular / parallel," i.e., "perpendicular / parallel" or "essentially perpendicular / parallel," meaning perpendicular / parallel except for a specified deviation. The specified deviation may, for example, be at most 15°, preferably at most 5°, and most preferably at most 3°. Similarly, in the context of this disclosure, "oppositely oriented" can be understood as "at least substantially oppositely oriented," i.e., "at least substantially antiparallel oriented." The limitation "essentially" may also refer to a specified maximum permissible deviation, for example, at most 15%, preferably at most 5%, and most preferably at most 3%. Detailed description Exemplary embodiments are described in more detail below with reference to schematic drawings. Figure 1 shows a top view of one plane of an exemplary embodiment of a spectacle display system; Figure 2 shows a top view of one plane of an exemplary embodiment of a spectacle display system with offset and overlapping micro-mirror units; Figure 3 illustrates the optimization of the geometry of the micro-mirror units with regard to reduced visibility; Figure 4 shows a top view of one plane of an exemplary embodiment of a spectacle display system with an additional focusing unit and vision correction; Figure 5 shows exemplary refractive indices of liquid and transparent material as a function of wavelength; Figure 6 shows proportionate Fresnel reflections as a function of the angle of incidence for an exemplary wavelength; Figure 7 shows wavelength-dependent refractive effects as a function of the angle of incidence and the wavelength; Figure 8 shows...Fig. 8 shows a top view of one plane of an exemplary embodiment of a spectacle display system with concave reflective surfaces; Fig. 9 shows a top view of one plane of another exemplary embodiment of a spectacle display system with concave reflective surfaces; and Fig. 10 shows an illustration of the deflection of the micro-mirror units by means of a guide matrix structure; and Fig. 11 shows a front view and interior view of another exemplary embodiment of a spectacle display system. In the figures, identical or functionally equivalent features are provided with the same reference symbols. Fig. 1 shows a top view of one plane of an exemplary embodiment of a glasses display system, exemplified for one half, i.e., for one eye. The system can be extended symmetrically for two eyes. Figure 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) and is focused by an optic 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 optic 13 can comprise one or more lenses and / or mirrors and / or other optical components such as one or more (also adaptive, i.e., adjustable with a control signal) aperture units. The eye is oriented in a central viewing direction B (here parallel to the y-direction).If the micromirror elements 12, 12', 12" (for example, with typical dimensions of approximately 2 mm) are at least substantially transparent to ambient light, then both viewing 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 micromirror elements 12, 12', 12" are mounted so that they can be tilted and angularly aligned in two dimensions. The micro-mirror elements 12, 12', 12" and a support structure 200 (Fig. 10), not shown for clarity, for the micro-mirror elements 12, 12', 12" are arranged in a sealed housing element 17a filled with a liquid 23. The liquid 23 is selected such 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 immersed in a liquid with a nearly identical refractive index. Two effects occur in this process. First, Fresnel reflection, which occurs when transitioning from one medium to another with a different refractive index, disappears. Second, light rays are not refracted at the material interface.However, even with very small differences, partial and total internal reflection are still possible if the angles meet the interface at very shallow angles. This is shown and explained in more detail in Fig. 6. In conjunction with determining 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" from the optics 13 very precisely into the pupil 11 of the eye 10. In the event of 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" from the optics 13 again falls precisely on the pupil 11.In addition to the support structure for the micro-mirror elements 12, 12',12" the micro-mirror elements 12, 12',12" are also equipped here with one or more actuator elements (not shown for clarity) for adjusting the angular alignment and thus the respective reflection angles, and additionally with an individual angle sensor (also not shown here) for measuring the current angular alignment. This enables a control loop for tracking the micromirror elements 12, 12', 12", so that the light 163", 161", 162" from the optics 13 strikes 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 alignment of the micromirror elements 12, 12', 12" is calculated by a control unit and then compared with the actual position of the micromirror elements 12, 12', 12". The actuator element(s) then adjust 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. Maximum eye speeds of 1000° / s are known, from which a minimum processing speed can be derived. 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, now deviating from the central viewing direction B. Comparing Fig. 1a and Fig. 1b, it is noticeable that the light 161" is reflected as light 161 in Fig. 1a and as light 161b in Fig. 1b, with the lights 161b and 161 differing in their direction. This results in a change in the assignment of the respective virtual pixels of the virtual image to a respective physical pixel of the display unit 14, and the image information emitted by the display unit 14 in the direction 161" must be adapted to the changed angular orientation. Therefore, in the event of eye movement, not only should the orientation of the micromirror elements 12, 12', 12" be adjusted, but also the pixel-light image information generated on the display unit 14. Since the geometric arrangement of the projector to the micromirrors 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 pupil location (predetermined "eyebox") perceives that the virtual image has not shifted, and a corresponding assignment rule can be stored in a control unit of the display unit 14. The micromirror elements 12, 12', 12'' are preferably controlled such that the central line of sight, i.e., the line of sight that starts from the center of the pupil and strikes the associated micromirror element at its 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 micromirror elements 12, 12', 12'', as explained, changes the angle at which pixel image information is seen by the display unit 14, it can be advantageous that the micromirror elements 12, 12', 12'' are not continuously adjusted, but rather in steps based on a limit value that specifies how off-center the light 163b may strike the pupil 11 of the eye 10. It is advantageous that the eye makes micro-movements which, as a consequence, do not need to be compensated for.Furthermore, it is 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). The micro-mirror elements 12, 12', 12'' are shown in a plane in Fig. 1. As shown in Fig. 2, however, they can also be arranged on a one- or two-dimensionally curved surface. Accordingly, the micro-mirror elements 12, 12', 12'' are arranged offset from one another in the central viewing direction, which runs transversely to a principal extension plane of the deflection unit 17 (here the xz-plane). For example, two, several, or all of the nearest adjacent micro-mirror elements 12, 12', 12'' are arranged offset from one another. This is advantageous because spectacle lenses typically have curved surfaces, the so-called base curves, and thus the spectacle display system 1 can be designed to be more similar to conventional spectacles. Furthermore, more of the micro-mirror elements 12, 12',12'' can be formed with mutual overlap and / or the extent of the overlap of respective adjacent micro-mirror elements 12, 12',12'' can be increased. Fig. 3a shows different geometries of the micro-mirror elements and their consequences for undesired refraction and reflection effects. The Fresnel reflection, which occurs when transitioning from one medium to another with a different refractive index, disappears due to the liquid 23 having an almost identical refractive index to the material of the micro-mirror elements 12, 12', and the light rays 21, 21', 22, 22' are not refracted. However, even with very small differences, partial and total internal reflection are still possible if the light rays strike the respective interfaces at a very shallow angle. For example, light ray 22'' is shown as such a partially reflected light ray. Accordingly, two micro-mirror elements 12 and 12' with different geometries are shown in Fig. 3a. Both micro-mirror elements 12 and 12' create a semi-transparent reflective surface 25, for example, by applying a thin metal coating to the micro-mirror elements 12, 12'. The micro-mirror elements 12, 12' themselves are made, for example, of a plastic or glass with a first refractive index that matches the second refractive index of the surrounding liquid 23 as closely as possible. The difference between the two exemplary micro-mirror elements 12 and 12' in Fig. 3a lies in their geometric construction. Micro-mirror element 12' creates interfaces where the sight rays of the human eye 10, corresponding to the light ray 22, strike the optical interface at a shallow angle. In this case, depending on the actual angle, total or partial internal reflection can occur. These reflections obscure the transparency of the deflecting unit 17, as the partial reflections superimpose ghost images. Therefore, it is advantageous for the mechanical structures of the micro-mirror element to be designed such that sight rays pass through interfaces with refractive index transitions as orthogonally as possible. Thus, the geometry of micro-mirror elements 12 with a rounded back surface is preferable to the rectangular geometry of micro-mirror elements 12'. Figure 3b shows a correspondingly different geometry of a micro-mirror element 12''. In this figure, the micro-mirror element 12'' has a trapezoidal geometry in the cross-section shown, with the long side of the trapezoid corresponding to the reflection surface 25. The light ray 23 passing through the two parallel base sides of the trapezoid is parallel before and after the micro-mirror element 12'' as well as before and after the deflection unit. However, the light ray 23' passing only through the long base side of the trapezoid and one of the legs is not parallel, as the interface at the leg is traversed at too shallow an angle. The trapezoidal geometry of micro-mirror elements 12'' is therefore preferable to the rectangular geometry of micro-mirror elements 12', but not to the geometry of micro-mirror elements 12 with a rounded back side. Figure 4 shows a top view 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'', acting as adaptive optics, is adjusted in its focus by a control unit 110. Thus, for example, the focus of the virtual image can be selectively set either to infinity (beam path / light beam 112) or to a finite point (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 single virtual image. With an additional lens element 13''' between deflection unit 17 and the surroundings 100, a visual acuity correction can be integrated here without much effort. Its properties must then be taken into account accordingly by the control unit 110. Fig. 5 shows exemplary refractive indices of a liquid, here an oil, and a transparent material, here quartz glass, as a function of wavelengths (wavelength in nm) from 400 nm to 700 nm at an exemplary temperature. Curve 80 corresponds to the first refractive index of the liquid 23, and curve 81 to the second refractive index of the material of the micromirror elements 12, 12', 12''. It should be noted that the maximum difference between the first and second refractive indices is reached here at 400 nm and does not exceed the relatively small value of 0.004. For these refractive indices, the values ​​for Fresnel reflections and refractive effects illustrated in Figs. 6 and 7 are obtained, resulting in largely invisible material transitions and thus largely invisible micromirror elements 12, 12', 12'' and largely invisible support structure or housing element 17a.It should also be noted that reflections can occur on the inner surface 17b (Fig. 1) of the housing element 17a, which faces the user and display unit 14, acting as a boundary layer. These reflections are disruptive due to the y-direction offset of the inner surface 17b relative to the micro-mirror elements 12, 12', 12''. These disruptive reflections can be reduced or eliminated with an anti-reflective coating, such as that found on conventional eyeglasses. In Fig. 6a, curve 82 shows the Fresnel reflection as a percentage of the total intensity versus the angle of incidence in degrees for the combination of the two refractive indices from Fig. 4 for a wavelength of 450 nm. The difference in the refractive indices is approximately 0.002. An exponential increase in the proportion of the reflected intensity due to this effect is evident. The reflection is close to zero up to an angle of incidence greater than 80° and increases to 100% within a few degrees towards 90°, i.e., when the light is incident at a shallow angle, almost grazing the interface (the angle of incidence is measured relative to a normal to the interface). Figure 6b shows that the reflected light fraction is below 0.01% up to approximately 70°, and therefore Fresnel reflection plays no role below this angle of incidence. Figure 6b plots the Fresnel reflection as a percentage of the total intensity ("reflection in % (100% max)") against the angle of incidence in degrees for the combination of the two refractive indices from Figure 4 for a wavelength of 450 nm from 0° to 70°. Curve 82a shows the curve for s-polarized light, and curve 82b for p-polarized light. In addition to the Fresnel reflections shown in Fig. 6, refractive effects must also be considered, which likewise depend on the angle of incidence and wavelength. Accordingly, Fig. 7 shows the wavelength-dependent refractive effect, a change in direction in degrees, as a function of the angle of incidence and the wavelength from 400 nm to 700 nm. The temperature and refractive indices here correspond to those in Figs. 4 and 5. The solid curves 83a, 83i, and 83z describe the deflection of light incident from the optically denser medium to the optically less dense medium for wavelengths from 400 nm (curve 83a) to 700 nm (curve 83z). The dashed curves 84a..84i..84z describe the deflection of light passing from the optically less dense medium into the optically denser medium for wavelengths from 400nm (curve 84a) to 700nm (curve 84z). Deviations in a core area W around 0 degrees are not perceived by the user due to the angular resolution of the human eye, which is limited to approximately 1 / 60° = 0.0167, and are therefore not critical. Thus, for example, curves 83i and 84i show that angles of incidence up to approximately 38° for wavelengths above 550 nm cannot be perceived by the user and are therefore not critical. From such representations, an optimized geometry for the micro-mirror elements 12, 12', 12'' can be derived depending on the overall geometry of the spectacle display system 1. Figure 8 shows a top view of a plane of an exemplary embodiment of a glasses display system with concave reflective surfaces. The principle shown avoids the need for multiplexing. This approach is particularly light-efficient, as all the light 163'', 161'', 162'' is directed into the pupil 10 of the eye 11. For this purpose, the optics 13' are designed such that the light from the display unit 14 is projected onto an intermediate image 101. However, the intermediate image 101 does not need to be sharply focused. It can be advantageous, for example, to compensate for aberrations that occur due to subsequent reflection at a curved micromirror element 12, 12', 12'' at this point. The intermediate image 101 is selected such that it is projected into the pupil 11 of the eye 10 by a curved micromirror element 12, 12', 12''. Due to the geometric constellation of pupil position to micro-mirror element 12, 12', 12'' and the diameter of pupil 11 and micro-mirror elements 12, 12', 12'', a viewing area 102 or 103 is spanned by a micro-mirror element 12 or 12'.The intermediate image 101 is positioned so that adjacent viewing areas 102 and 103 do not overlap. Thus, the light 163'', 161'', 162'' of a physical pixel of the display unit 14 is projected only onto one micro-mirror element 12, 12', 12'' and no further multiplexing process is necessary. In the embodiment shown in Fig. 8, each light ray 104, 105 has its own intermediate focus 106, 107, which is imaged onto the display unit 14 by its own physical pixel. Because such light rays 105 not only strike one micro-mirror element 12, but also another micro-mirror element 12', and this is again imaged onto a separate physical pixel on the display unit 14, redundant physical pixels are necessary, i.e., more physical pixels than virtual pixels displayed in the virtual image. In one variant, the intermediate image 101 can also be designed such that adjacent viewing areas 102, 103 overlap. The corresponding micromirror elements 12, 12' are then designed so that the same intermediate focus 107 is used for the same viewing angles falling on the pupil 11, thus requiring only one physical pixel per viewing direction. This design is optically more demanding because the micromirror elements 12, 12', 12'' must not only produce a sharp image, but also control the distortion so that adjacent micromirror elements 12, 12', 12''' with different tilt angles must project a common intermediate image 101. In the design of the optics 13', it can be used that maximum sharpness only needs to be achieved for a central area, the so-called "foveated area", i.e. when the eye 10 is precisely aligned with the respective micro-mirror element 12, 12', 12'''.When the eye turns away, human visual performance drops rapidly and significantly, so that image errors are usually not perceived in this case. Fig. 9 shows a top view of a plane of another exemplary embodiment of a spectacle display system with concave reflective surfaces, which is similar to that shown in Fig. 8, but optionally does without the optics 13'. The micromirror elements 12, 12', 12''' are designed to focus directly onto the display unit 14. Additional optical elements 13''' can be inserted to improve image quality. Thus, all micromirror elements 12, 12', 12''' simultaneously image the display unit 14. To unambiguously image pixel information in a specific viewing direction, a multiplexing method must be used. A suitable multiplexing method is one based on a switchable, adjustable aperture unit, allowing unwanted micromirror elements 12, 12', 12'' to be blocked at any given time, while the aperture unit remains transparent only to desired micromirror elements. Such a switchable, adjustable aperture unit can be implemented, for example, using a liquid crystal shutter. In different embodiments, the focus of the micromirror elements 12, 12', 12''' can thus be located at different distances. Fig. 8 shows an example where the focus 101 is in front of the display unit 14. In Fig. 9, the focus is on the display. The focus can also be located behind the display unit 14 at infinity. The focal plane can therefore be freely selected in front of, on, or behind the display unit 14. If pixel information is mapped onto several micromirror elements 12, 12', 12''' simultaneously, a multiplexing method, such as the one described in the last paragraph, is necessary to unambiguously represent pixel information in one image direction. Fig. 10 shows an illustration of the deflection of the micro-mirror units using a guide matrix structure. Fig. 10a shows an example of a micro-mirror unit 12, which is arranged on a support structure 200 so that it can be tilted about two tilting axes K1, K2. A two-dimensional guide matrix structure 202 with respective guide surfaces 203a, 203a', 203b, 203c, 203d is formed on a common actuator element 201 (Fig. 10b). The respective micro-mirror units 12, 12', 12'' scan the guide matrix structure 202 in the form of the associated guide surfaces 203a, 203a', 203b, 203c, 203d with respective sensors 204a, 204a', 204b, 204c, 204d, one sensor per tilting axis K1, K2, so that when the actuator element 201 is displaced, the respective micro-mirror units 12, 12', 12'' can be tilted non-linearly by the displacement of the actuator element 201 in different ways according to the spatial shape of the guide surfaces 203a, 203a', 203b, 203c, 203d. In Fig. 10b, this is shown in a sectional view for one dimension of tilting. For example, two micro-mirror units 12, 12'' are tilted counterclockwise when the actuator element 201 is moved in the negative x-direction, while another micro-mirror unit 12' is tilted clockwise. Figure 11 shows another exemplary embodiment of a spectacle display system. As can be seen in Figure 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 within a field of view corresponding to that of conventional spectacles. Figure 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', which partially overlap, are shown by way of example. In the example shown, the micro-mirror units 12, 12', 12'' are offset in the y-direction and are also of different sizes. Micro-mirror unit 12'' has a larger reflective surface than micro-mirror unit 12', and micro-mirror unit 12' has a larger reflective surface than micro-mirror unit 12.

Claims

Spectacle display system (1) for displaying a virtual image in a user's field of vision, comprising: - a display unit (14) for emitting light (163", 161", 162") as computer-generated image information in a direction of emission; - 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, comprising a plurality of micro-mirror elements (12, 12', 12") which are each tiltable in a carrier structure (200) and each have a reflective surface (25) for deflecting the light (163", 161", 162") emitted by the display unit (14) as computer-generated image information;characterized in that the micro-mirror elements (12, 12', 12") and the support structure (200) are arranged in a sealed housing element (17a) of the deflection unit (17) filled with a liquid (23) and the micro-mirror elements or the support structure are each at least substantially transparent to ambient light from the user's field of vision. Eyeglass display system (1) according to the preceding claim, characterized in that the micro-mirror elements (12, 12', 12") and the support structure (200) are each at least substantially transparent to ambient light from the user's field of vision, in particular invisible to the user in at least one wavelength range and / or at least one angular range of the ambient light, and are made of or with a respective transparent material having a first refractive index; and the liquid (23) is also at least substantially transparent to ambient light and has a second refractive index adapted to the first refractive index in the sense of the smallest possible deviation. Eyeglass display system (1) according to one of the preceding claims, characterized in that the micro-mirror elements (12, 12',12") are mechanically coupled to a common actuator element (201), in particular by means of a two-dimensional guide matrix structure (202). Eyeglass display system (1) according to the preceding claim, characterized in that the actuator element (201) is configured to move at least some of the micro-mirror elements (12, 12',12"), in particular most of the micro-mirror elements (12, 12',12"), differently from each other and / or non-linearly. Eyeglass display system (1) according to one of the preceding claims, characterized in that the reflective surfaces (25) are each hexagonal reflective surfaces (25), and in particular the respective micro-mirror element (12, 12',12") has a coating on its reflective surface (25). Eyeglass display system (1) according to one of the preceding claims, characterized in that the reflective surfaces (25) have at least partially different sizes, in particular one or more reflective surfaces (25) closer to a central viewing axis (B) of the user have a smaller size than one or more reflective surfaces (25) further away from the central viewing axis (B) of the user. Eyeglass display system (1) according to one of the preceding claims, characterized in that the reflective surfaces (25) are concave reflective surfaces (25). Eyeglass display system (1) according to one of the preceding claims, characterized in that the carrier structure (200) and / or the micro-mirror elements (12, 12', 12") are shaped such that the ambient light from the user's field of vision passes through interfaces between transparent material and liquid (23) and / or between liquid (23) and transparent material at least predominantly at small angles, in particular at least predominantly at angles of less than 45°. Eyeglass display system (1) according to one of the preceding claims, characterized in that the reflective surfaces (25) of at least some micro-mirror elements (12, 12',12") overlap in an orthogonal projection onto a plane running perpendicular to the central viewing axis (B) of the user. Eyeglass display system (1) according to the preceding claim, characterized in that the reflective surfaces (25) of the micro-mirror elements (12, 12',12") overlap in a vicinity of the user's central line of sight (B) in the orthogonal projection. Eyeglass display system (1) according to one of the preceding claims, characterized in that the micro-mirror elements (12, 12',12") are arranged in a one- or two-dimensionally curved surface. Eyeglass display system (1) according to one of the preceding claims, characterized in that the housing element (17a) has an anti-reflective coating on a side (17b) facing the display unit (14), in particular an anti-reflective coating which varies locally in its anti-reflective properties. Eyeglass display system (1) according to one of the preceding claims, characterized by an eye tracking device (15) for determining the orientation of the user's eye (10), and a control unit for controlling the deflection unit (17) depending on the result of determining the orientation of the eye (10). Eyeglass display system (1) according to the preceding claim, characterized in that the control unit is also designed to control the display unit (14) according to an assignment rule stored in the control unit, wherein the assignment rule specifies an assignment of the respective virtual pixels of the virtual image to a respective physical pixel of the display unit (14) that changes depending on the orientation of the eye (10). Eyeglass display system (1) according to one of the preceding claims, characterized by a temperature control device for the liquid, comprising 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.

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