Image projection device for the polychromatic projection of an image into a viewing field

Abstract

The invention relates to an image projection device for the polychromatic projection of an image into a viewing field (7), wherein the image projection device (2) comprises: a plurality of MEMS projectors (11R, G, B) for image projection by means of electromagnetic radiation, wherein the emission spectra of the radiation from the MEMS projectors (11R, G, B) differ from one another in at least one wavelength range; and a waveguide device (1) for guiding the radiation that can be emitted by the MEMS projectors (11R, G, B), wherein the waveguide device (1) has: one or more waveguides (3); for each MEMS projector (11R, G, B), a separate coupling-in device (4) for coupling at least a portion of the radiation that can be emitted by the MEMS projector (11R, G, B) into the or an associated waveguide (3) such that the beam paths of the different MEMS projectors (11R, G, B) in the waveguide device (1) extend spatially separated from one another at least in sections; and, for each waveguide (3), at least one coupling-out device (5) for coupling out at least a portion of the radiation guided through the waveguide (3) into the viewing field (7) located outside the waveguide device (1), such that the coupled-out radiation from the different MEMS projectors (11R, G, B) combines in the viewing field (7) to form a projected polychromatic overall image.

Description

[0001] IMAGE PROJECTION DEVICE FOR POLYCHROMATIC PROJECTION OF AN IMAGE INTO AN OBSERVATION FIELD

[0002] The present invention relates to an image projection device for polychromatically projecting an image into an observation field, as well as to glasses and a handheld projector, each comprising such an image projection device.

[0003] The projection of images is no longer limited to long-distance projection, such as on screens in cinemas, event halls, or meeting rooms (for example, for presentations). Rather, it has recently gained enormous importance in the technical field of so-called extended reality (XR), especially as close-up projection, especially in connection with so-called "XR glasses." The term "extended reality (XR)" should be understood as a collective term for augmented reality (AR), virtual reality (VR), and mixed reality (MR). These technologies all aim to combine or mirror the physical world with a "digital twin world" that can interact with it.

[0004] Depending on the type of XR, the viewer is presented with only artificial images (in VR) or a combination of artificial and real images (in AR and MR), whereby the real images can also be or include a reproduction of images captured using image sensors.

[0005] A display of XR images to a viewer can be achieved specifically by presenting the images to the viewer via glasses and thus in the near field of the human eye (XR glasses). While one known technology, particularly suitable for VR, uses classic display technology in the glasses (the glasses have screens (displays) that are thus worn close to the eyes), another display technology is based on optically coupling the images to be displayed into one or both lenses in such a way that a viewer (particularly the wearer of the glasses) perceives them as images displayed on the surface of the lenses. Another alternative is the use of head-up display technology, which, similar to the technology of the same name known from automotive technology, projects the images from outside the lenses onto them as a projection surface.

[0006] One particularly space-saving way to project images is to use microscanner systems designed as projectors. They contain one or more microscanners, which in technical terms are also referred to as "MEMS scanners", "MEMS mirrors" or "micromirrors", or in English in particular as "micro-scanners" or "micro-scanning mirrors" or "MEMS mirrors". These are micro-electro-mechanical systems (MEMS), more precisely micro-opto-electro-mechanical systems (MOEMS), from the class of micromirror actuators for the dynamic modulation of electromagnetic radiation, in particular visible light. Depending on the design, the modulating movement of an individual mirror can be translational or rotational about at least one axis.In the first case, a phase-shifting effect is achieved, while in the second case, a deflection of the incident electromagnetic radiation in a direction dependent on the current orientation of the mirror is achieved. In some microscanner designs, which can also be used in particular within the scope of the present invention, the modulating movement of an individual mirror is, at least partly, rotational. In contrast to mirror arrays, in which the modulation of incident light occurs via the interaction of several mirrors on a single MEMS component, the modulation in microscanners is typically generated via a single mirror per MEMS component (microscanner).

[0007] Microscanners can therefore be used, in particular, to deflect electromagnetic radiation by modulating the deflection direction of an incident electromagnetic beam, particularly a laser beam, using a deflection element (“mirror”). This can be used, in particular, to create a Lissajous projection of the beam into an observation field. This allows imaging tasks, in particular, to be solved and display functionalities to be realized.

[0008] The term "Lissajous projection" (and variations thereof), as used herein, is to be understood in particular as a scanning of an observation field by means of electromagnetic radiation, which is effected by at least two mutually orthogonal harmonic oscillations of a deflection device deflecting the radiation into the observation field, in particular a single deflection element or a combination of at least two deflection elements, in particular mirrors.

[0009] A microscanner can be implemented in a mostly plate-shaped substrate, especially a semiconductor chip. Microscanners often have a mirror plate (deflection plate) suspended laterally on elastically stretchable springs. A distinction is made between single-axis mirrors, which are preferably mounted for rotation about only a single axis, and dual-axis and multi-axis mirrors, in which rotations (especially rotational oscillations) about a corresponding number of different axes (oscillation axes) are possible, especially simultaneously.

[0010] A microscanner system for deflecting an electromagnetic beam can thus, in particular, comprise a biaxial microscanner, i.e., a microscanner with two different non-parallel, in particular mutually orthogonal, oscillation axes. However, it is also possible for the microscanner system to comprise a combination of two or more individual microscanners, in particular single-axis microscanners, arranged such that the incident beam can be deflected successively by the various individual microscanners of the microscanner system to generate a two-dimensional deflection pattern, such as a raster scan or a Lissajous pattern. In a microscanner system with a combination of two or three single-axis microscanners, their non-parallel oscillation axes can, in particular, be orthogonal to one another in pairs.

[0011] The term “MEMS projector” is understood herein to mean a projector which has a MEMS, in particular a microscanner system, and at least one radiation source for providing electromagnetic radiation to be deflected by the MEMS to effect an image projection.

[0012] For a range of different MEMS projector applications, particularly for applications in the field of so-called "wearables," i.e., electronics worn on the body, very compact and cost-effective MEMS projectors are required, especially laser MEMS projectors. A key design for this purpose features one or more microscanners for beam deflection and one or more laser sources. Wearables include, in particular, virtual reality (VR) glasses, augmented reality (AR) glasses, mixed reality (MR) glasses, and other body-worn imaging devices, as well as other portable image projectors (sometimes referred to as "pico-projectors"). The waves of the radiation generated by the radiation sources (especially laser sources) can lie in the visible range of the spectrum and can be, in particular, primary colors of a color model for a color space.For example, in the case of an RGB color model, the radiation sources can be provided by three laser sources, e.g., laser diodes, each configured to emit red, yellow, or blue laser light. With a view to achieving high user comfort and high display quality for image projection devices, particularly in connection with so-called wearables, which also include XR glasses and other portable image projectors, it is desirable to achieve a high degree of miniaturization while simultaneously maintaining high image quality for image projection devices for use (particularly as components or parts) in portable projection devices.

[0013] One object of the present invention is to address the above-mentioned problem. In particular, it is intended to provide an image projection device suitable for image display using XR glasses, especially very lightweight XR glasses.

[0014] To solve this problem, the respective devices are proposed according to the teaching of the independent claims. Various embodiments and further developments of the solution are the subject of the subclaims.

[0015] A first aspect of the solution presented here concerns an image projection device for polychromatically projecting an image into an observation field. The image projection device comprises:

[0016] (i) a plurality of MEMS projectors for image projection by means of electromagnetic radiation, wherein the emission spectra of the radiation of the MEMS projectors differ from one another in at least one wavelength range; and

[0017] (ii) a waveguide device for guiding the radiation emittable by the MEMS projectors.

[0018] This waveguide device has:

[0019] (ii-1) one or more waveguides;

[0020] (ii-2) a separate coupling device for each MEMS projector for at least partially coupling the radiation emitted by the respective MEMS projector into the associated waveguide(s) in such a way that the respective beam paths of the various MEMS projectors extend spatially separated from one another in the waveguide device, at least in sections; and

[0021] (ii-3) at least one output device per waveguide for at least partially outputting the radiation guided through the waveguide into the observation field located outside the waveguide device, such that the output radiation from the various MEMS projectors in the observation field is superimposed to form a projected polychromatic overall image. The term "image projection," as used herein, refers to an enlarged, reduced, or otherwise modified transmission of an image onto a projection surface. Accordingly, the term "image projection device" is understood herein to refer to a device configured to perform an image projection.

[0022] The term "polychromatic", as used herein, in contrast to "monochromatic", refers to the multi-color nature of electromagnetic radiation. In this context, the term is not restricted to radiation from the region of the electromagnetic spectrum visible to the human eye (i.e., light), but can also or instead refer to other regions of the spectrum, such as infrared or ultraviolet radiation. Polychromatic radiation is thus to be understood as radiation in whose spectrum not only radiation in a very narrow (i.e., monochromatic) wavelength range occurs, but at several significantly different wavelengths (e.g., by > 10 nm). Thus, more than just one spectral color (also in the above-mentioned expanded sense beyond light) is present in polychromatic radiation.

[0023] The term "waveguide," as used herein, refers to a body configured to conduct electromagnetic radiation within its interior as a wave from one location to the next, in this case between the input coupling device and the output coupling device. Optical fibers, in particular, are considered waveguides. The waveguiding within the body can, in particular, be based solely or partially on the effect of total internal reflection. With regard to the aforementioned application of XR glasses, a waveguide can, in particular, be designed as a spectacle lens or integrated therein. Besides glass, other spectacle lens materials are also possible, such as plastics that are largely transparent in the relevant wavelength range (cf. plastic spectacle lenses in conventional visual aids, sunglasses, or other safety goggles).

[0024] The term "coupling device," as used herein, refers to a device suitable for coupling electromagnetic radiation into a waveguide. In particular, a coupling device may comprise an optical grating (diffraction grating). Such a coupling device of a waveguide is also often referred to in technical terms as a "pupil" or "entrance pupil." It may, in particular, have a rectangular, circular, or elliptical shape.

[0025] In contrast, the term "outcoupling device," as used herein, refers to a device suitable for coupling electromagnetic radiation out of a waveguide. In particular, an outcoupling device can comprise an optical grating (diffraction grating). Technically, an input coupling device can be designed in particular similarly to an input coupling device, so that in this case, the two devices do not differ as such. Rather, their function is determined by their arrangement in the beam path, in that radiation is coupled in at the input coupling device, which is then at least partially guided through the waveguide to the location of the output coupling device (waveguiding can be based in particular on the phenomenon of total internal reflection (ITR)), where it is then at least partially decoupled from the waveguide again.

[0026] In an image projection device according to the invention, the radiation provided by the MEMS projectors is coupled into the waveguide device in a spatially separate manner. This allows, in particular, the propagation paths of the beams from the various MEMS projectors to be kept separate within the waveguide device, at least in some sections, so that dispersion-related effects that could adversely affect image quality can be reduced or even largely avoided. Dispersion can occur, in particular, in each of the waveguides as well as at the coupling and / or decoupling devices.

[0027] This also improves the uniformity and average transmission, i.e., the cumulative radiation transmission across the wavelengths of all participating MEMS projectors, across the observation field (in the case of XR glasses, this means the wearer's field of vision). The projected image can thus be improved to the extent that it appears brighter and more uniform to the viewer in terms of color reproduction.

[0028] Due to the color-separated coupling, the different colored radiation beams from the various MEMS projectors do not need to be combined or superimposed before coupling into the waveguide device. In particular, it is possible to use monochromatic MEMS projectors, one for each required spectral color, which together project a polychromatic image using the waveguide device.

[0029] A further achievable advantage can be that the beam trajectories of the individual MEMS scanners (microscanners) can run independently (= asynchronously) of one another. In this case, it is possible, primarily when using a Lissajous projection, to reduce any "flicker artifacts" during projection to such an extent that they are less noticeable to the viewer, thus leading to a more pleasant image impression. With regard to the desired miniaturization, the use of particularly small projectors is advantageous, which is achieved in the present solution by the MEMS design of the MEMS projectors. Particularly advantageous designs will be described below in the context of various embodiments.Furthermore, particularly compact designs for MEMS projectors that can be used within the solution are described in detail in the following patent applications, the contents of which are incorporated herein in their entirety by reference:

[0030] DE 10 2023 114 273.9, DE 10 2023 114 283.6, DE 10 2023 115 670.5

[0031] DE 10 2023 115 640.3, DE 10 2022 134 418.5, DE 10 2023 115 654.3

[0032] DE 10 2023 120 394.0, DE 10 2023 120 395.9.

[0033] In the following, various exemplary embodiments of the image projection device are described, which, unless this is expressly excluded or is technically impossible, can be combined with each other as desired and with the other aspects of the solution described below.

[0034] In some embodiments, at least one of the MEMS projectors is configured to emit monochromatic radiation. This enables a reduction in the complexity of the MEMS projection compared to polychromatic MEMS projectors.

[0035] In some embodiments, the image projection device specifically comprises at least three monochromatic MEMS projectors, whose emission wavelengths are selected to be different such that together they span an at least three-dimensional color space, in particular according to the RGB color model. Thus, the combination of the waveguide device according to the invention with the monochromatic MEMS projectors enables polychromatic image projection with high color variability.

[0036] In some embodiments, the waveguide device comprises one, in particular exactly one, waveguide, which has a separate coupling device for each MEMS projector for at least partially coupling the radiation emittable by the respective MEMS projector into the waveguide such that the respective emitted radiation beams of the various MEMS projectors run spatially separated from one another in the waveguide, at least in sections. This enables, in particular, implementations in which the radiation beams of the various MEMS projectors run along at least partially separate beam paths within a single waveguide of the waveguide device (with the aforementioned advantages with regard to dispersion) and are nevertheless coupled out of the waveguide into the observation field at a common coupling device in order to jointly display a polychromatic image.

[0037] In some embodiments, a replication device is arranged in the beam path of at least one of the beams for at least partial deflection (so-called pupil replication) of the beam. This allows particularly effective separate beam paths for the various beams of the MEMS projectors coupled into the same waveguide, such that the beams converge (in particular only) in the region of the output device and superimpose to form a polychromatic image. Thus, the aforementioned undesirable dispersion-related effects on the image can be minimized.

[0038] In some embodiments, the waveguide device comprises a plurality of waveguides, each of which is assigned to one of the MEMS projectors in such a way that its radiation can be at least partially coupled into a coupling device of the respective waveguide, so that the respective beam bundles of the various MEMS projectors extend through different waveguides and are thus spatially separated from one another, at least in sections. This allows for a particularly clear separation of the beam paths between the coupling and the output. In particular, these beam paths can now even run parallel to one another. The individual waveguides can thus be simplified.For coupling out, each of the waveguides advantageously has its own coupling device, wherein the coupling devices of the different waveguides spatially overlap, so that the beams coupled out from the different waveguides can overlap in the observation field, in particular already in the area of ​​overlap, to form the projected polychromatic image.

[0039] In some embodiments with multiple waveguides, these waveguides are each formed as flat or curved plates and arranged one above the other as different layers of a stack. In particular, the waveguides stacked in this way can together form a lens of XR glasses or be a component thereof, allowing a particularly compact, solution-based implementation with strong beam path separation for the beams of different MEMS projectors, especially for such devices.

[0040] In some embodiments, the waveguiding device is configured such that the radiation guided by it from at least two of the MEMS projectors exits the waveguiding device at a radiation exit surface on the surface of the waveguiding device that is common for this radiation. In this way, superposition can be achieved already at the location of the radiation exit (and not just deeper in the field of observation). This is particularly advantageous with regard to enabling very short spatial distances between the radiation exit surface and the observer's eye. The output coupling device(s) of the waveguide(s) are then expediently arranged in the region of the radiation exit surface (i.e. spatially overlapping and preferably in close spatial proximity to it).

[0041] In some embodiments, at least one of the ME MS projectors has a microscanner as an imaging element for image projection. As already mentioned at the beginning, this allows for particularly compact designs and good image quality.

[0042] In some of these embodiments, at least one MEMS projector with a microscanner is configured to operate its microscanner as a Lissajous microscanner. For this purpose, appropriate control logic may be provided, in particular, to control a drive of the microscanner, more precisely its deflection element (mirror), to generate a Lissajous-shaped trajectory (which can also be done, in particular, within the framework of trajectory control).

[0043] In some embodiments, at least two of the MEMS projectors are designed as separate components. This allows for at least largely individual optimization of each of the MEMS projectors, independent of the others. This also allows for maximum freedom regarding the placement of the MEMS projectors relative to the waveguide device, although the respective location of the coupling devices must usually be determined depending on the location of the associated MEMS projector, or vice versa.

[0044] In some embodiments, instead or additionally, at least two of the MEMS projectors are monolithically integrated into a common substrate. This allows for particularly compact designs. In particular, individual housing for each MEMS projector can be dispensed with in favor of a space-saving common housing for the integrated MEMS projectors. Furthermore, due to the integration, production can be parallelized and thus made more efficient.

[0045] Specifically, in some of these embodiments, the image projection device can have at least three MEMS projectors that are monolithically integrated into the common substrate and positioned in a row arrangement extending along a straight line. The distances between the respective MEMS mirror of the MEMS projectors and the associated entrance pupil can then be selected to be the same for all MEMS projectors, and thus colors or spectra, in particular for manufacturing reasons. The effort (manufacturing, installation space) for such an integrated solution can then be reduced compared to the sum of the efforts for three separate monochrome projectors. In particular, by eliminating "partition walls" between the adjacent elements of the various MEMS projectors, manufacturing steps such as "die separation" and "assembly of all MEMS projectors into one assembly" can be eliminated.In this way, a particularly dense packing of the components can be achieved and the length of their arrangement along the straight line can be kept short or shortened.

[0046] In particular, the straight line can coincide with a virtual coupling-tilt axis or run parallel to it, so that in the MEMS projectors, during operation, radiation to be imaged by the associated microscanner is directed in a radial direction relative to the coupling-tilt axis onto a movable deflection element of the respective microscanner.

[0047] In some further embodiments, the image projection device comprises at least three MEMS projectors that are monolithically integrated into the common substrate and positioned in a triangular configuration. This allows, in particular, a particularly compact image projection device to be produced, which may, in particular, exhibit (threefold) rotational symmetry. Accordingly, the triangular configuration may, in particular, correspond to an equilateral triangle.

[0048] A second aspect of the solution relates to glasses, in particular XR glasses, comprising an image projection device according to the first aspect for the polychromatic projection of an image into a field of view overlapping with the field of observation of an observer wearing the glasses.

[0049] A third aspect of the solution relates to a handheld projector, comprising an image projection device according to the first aspect for polychromatically projecting an image onto a projection surface located in the field of view, e.g., a wall or screen. A handheld projector is also commonly referred to as a pico projector.

[0050] The features and advantages explained with regard to the first aspect of the solution also apply accordingly to the other aspects of the solution. The solution is explained in more detail below using drawings that merely represent exemplary embodiments. Further advantages, features, and possible applications of the present solution emerge from the following detailed description in conjunction with the figures, each of which merely represents exemplary embodiments.

[0051] It shows:

[0052] Fig. 1 shows an exemplary embodiment of a waveguide device in the form of a spectacle lens with three stacked waveguides, each with its own coupling device designed as an entrance pupil;

[0053] Fig. 2 shows several different detailed views of the waveguide device from Fig. 1;

[0054] Fig. 3 shows a further exemplary embodiment of a waveguide device in the form of a spectacle lens with a single waveguide with three spatially separated coupling devices, here specifically arranged in series and each designed as an entrance pupil for an associated MEMS projector;

[0055] Fig. 4 shows an exemplary embodiment of an image projection device with a waveguide device with three stacked waveguides and three MEMS projectors, each of which is assigned to one of the waveguides and is in particular monochromatic;

[0056] Fig. 5 shows a further exemplary embodiment of an image projection device with a waveguide device with three stacked waveguides and three MEMS projectors, each assigned to one of the waveguides, in particular each monochromatic, which are monolithically integrated and arranged in series;

[0057] Fig. 6 shows a perspective view of a first exemplary embodiment of a monolithically integrated combination of three MEMS projectors in a single component, which can be used in particular in the embodiment of Fig. 5;

[0058] Fig. 7 shows a perspective view of a second exemplary embodiment of a monolithically integrated combination of three MEMS projectors in a single component, which can be used in particular in the embodiment of Fig. 5;

[0059] Fig. 8 shows a perspective view of a third exemplary embodiment of a monolithically integrated combination of three MEMS projectors in a single component, which can be used in particular in the embodiment of Fig. 4; and

[0060] Fig. 9 shows an exemplary embodiment of a handheld projector with an image projection device according to the solution.

[0061] In the exemplary first embodiment of a waveguide device 1 of an image projection device 2 according to the solution, illustrated in Fig. 1 (cf. e.g. Fig. 4), this is designed in the shape of a spectacle lens and has three layers stacked on top of one another, each forming a waveguide 3. The individual layers can in particular be made of a glass or polymer material (plastic) that is at least partially transparent to the wavelengths or wavelength ranges of the electromagnetic radiation to be conducted through them (in the present case of a spectacle lens shape, therefore typically light). Each of the waveguides 3 can guide electromagnetic radiation (waves) in its interior as traveling waves due to total internal reflection occurring at its interfaces.Accordingly, an intermediate layer (not shown) can be located between each two adjacent waveguides 3, the refractive index of which is lower than that of the waveguides 3 adjacent to it.

[0062] Each of the waveguides 3 has its own coupling device 4, which is designed, for example, with a circular area (as shown), and which is spatially separated from the coupling devices 4 of the other waveguides 3. Each coupling device 4 has an optical grating (diffraction grating), in particular a Bragg grating, in order to at least partially couple radiation incident on the coupling device 4 from outside the associated waveguide 3 into the waveguide 3. Each of the waveguides 3 and its associated coupling device 4 can in particular be assigned to a specific wavelength range or, in the case of monochromatic radiation, even to only a single spectral color. In particular, a grating constant of the optical grating can be selected depending thereon in order to optimize the coupling of the respective radiation, for example with regard to the (e.g.in relation to the radiation energy) of the radiation incident on the grating, which is coupled into the associated waveguide 3. In a central region of the waveguide device 1, through which in particular a main line of sight (straight ahead view) of a spectacle wearer can run through the waveguide device 1 when this is used as a spectacle lens for XR spectacles, in particular AR or MR spectacles, an associated decoupling device 5 is arranged for each waveguide 3, which is configured to decouple the radiation guided through the respective waveguide 3 from it, so that it can leave the respective waveguide 3 at the decoupling device 5.The output coupling devices 5 of the various waveguides 3 are arranged spatially overlapping in the region of a radiation exit surface 6 such that the radiations output from the individual waveguides 3 overlap at the radiation exit surface 6 to form an overall image in order to project this overall image into an observation field 7 adjacent to the radiation exit surface 6. A human eye of the spectacle wearer can expediently be located in the observation field 7 in order to visually capture the projected overall image.

[0063] Fig. 2 illustrates a further embodiment of a waveguide device 1, which represents a further development of the waveguide device 1 from Fig. 1 in that here the entrance pupils or coupling devices 4 are arranged in a row along a straight line. In the upper left area of ​​Fig. 2, a waveguide device 1 designed as a right-hand lens 1a (from the perspective of the spectacle wearer) can be seen, and in the upper right area of ​​Fig. 2, a waveguide device 1 designed as a left-hand lens 1b (from the perspective of the spectacle wearer).

[0064] In the lower part of Fig. 2, a sectional view through the left spectacle lens 1b along the section line AA and along the stacking direction of the stacked waveguides 3 is shown, from which the depth position of the coupling devices 4 for each waveguide 3 can be seen.

[0065] The outer surface of the waveguide 3 shown at the bottom in Fig. 2, which, when used as a lens for spectacles, faces the wearer's face and where the MEMS projectors 11 R, G, B can be attached to provide the radiation (see Fig. 5), corresponds to the lens surface located at the top right in the image, on whose surface the coupling device 4 for this waveguide 3 is located. The coupling devices 4 of the other waveguides 3, in contrast, are located correspondingly lower, each on the boundary surface of the respective waveguide 3 facing the lowest waveguide 3.

[0066] Fig. 3 illustrates an alternative embodiment of a waveguide device 1, in which only a single waveguide 3 is provided. In order to nevertheless achieve, at least partially, separate beam paths for the beams arriving at different entrance pupils or coupling devices 4, replication devices 8 are arranged at various locations within the waveguide 3 for at least partially deflecting the respective beams reaching them in the direction of the radiation exit surface 6. These can again be optical gratings, in particular Bragg gratings, which are positioned and oriented with respect to the grating alignment depending on the location of the associated entrance pupil and the radiation exit surface 6.

[0067] Specifically, as shown, three spatially separated entrance pupils, in particular arranged in series, can be provided on the waveguide 3. In order to be able to span an RGB color space, for example, a first entrance pupil 4R for red light, a second entrance pupil 4G for yellow light and a third entrance pupil 4B for blue light can be present. The respective light can for this purpose be monochromatic, so that essentially only three different spectral colors are used to generate the projection. The coupling devices 4 of the three entrance pupils are each defined with regard to their grating constants and their grating orientation such that the light beam (in particular laser beam) of the associated color coupled into them propagates predominantly as a bundle of rays to the associated replication device 8, where it is deflected towards the radiation exit surface 6.Overall, the blue light thus results from a first "blue" beam path 9B leading to the associated replication device 8 and a second "blue" beam path 10B leading from the replication device 8 to the radiation exit surface. The same applies to the other two colors (first "yellow" beam path 9G and second "yellow" beam path 10G) or (first "red" beam path 9R and second "red" beam path 10R).

[0068] Fig. 4 illustrates (proportionately for only one spectacle lens) in a front view and a rear view an exemplary embodiment of an image projection device 2 based on the waveguide device 1 from Fig. 1. To generate the radiation to be projected, an associated MEMS projector 11 R, G, B is arranged on the waveguide device 1 for each waveguide 3 in such a way that it can radiate its radiation into the respective entrance pupil of the waveguide 3 of the waveguide device 1 assigned to it. In the present example, a first MEMS projector 11 R for red light, a second MEMS projector 11 G for yellow light, and a third MEMS projector 11 B for blue light are provided to span an RGB color space (of course, other color spaces are also conceivable), each of which is designed as a separate component with its own housing.Preferably, they are each designed to emit monochromatic light of the corresponding color, for example by means of a laser diode of the corresponding color as radiation source 12R,G,B.

[0069] Fig. 5 illustrates (proportionately for only one spectacle lens) a further exemplary embodiment of an image projection device 2, but based on the waveguide device 1 from Fig. 2 with entrance pupils arranged in a row. In contrast to Fig. 4, here the MEMS projectors 11 R, G, B for the different wavelength (ranges) or colors are monolithically integrated in a single component 13 and are also arranged in a row corresponding to the sequence of the entrance pupils. In this way, a very small form factor can be achieved for the component 13. Fig. 5 also shows the beam paths between a respective radiation source 12 R, G, B (e.g. laser diode or LED) of the MEMS projectors 11 R, G, B, to a respective microscanner arranged in the component 13 and from there as a mirrored (deflected or scanned) beam to the associated entrance pupil in the waveguide device 1 orthe left lens 1 b is shown as cylindrical envelopes.

[0070] Fig. 6 illustrates a perspective view of a first exemplary embodiment of a monolithically integrated combination of three MEMS projectors 11 R, G, B in a single component 13, which may in particular correspond to the component 13 from the embodiment of Fig. 5.

[0071] The component 13 has a multi-layer structure, whereby in this case, in simplified form, only a base substrate 14 is provided, which in particular can consist largely of a semiconductor material, for example silicon, in which one or more integrated circuits for controlling or driving the microscanners and / or for driving the radiation sources 12R,G,B (e.g., laser diodes) of the MEMS projectors 11R,G,B are formed. The deflection elements (mirrors) of the microscanners are formed in an overlying MEMS layer 15, which can also be made, at least predominantly, of a semiconductor material, and are movably suspended in such a way that they can execute a two-dimensional rotational oscillation in order to scan the beam incident on them from the respectively assigned radiation source 12R,G,B into the entrance pupil of the assigned waveguide 3 (not shown here).The MEMS projectors 11 R, G, B are arranged in a row along a straight line that coincides with or runs parallel to a coupling tilt axis 16 of the optical image at the deflection elements of the microscanners. The component 13 can, in particular, also be used in combination with the single-layer embodiment of the waveguide device 1 from Fig. 3. Fig. 7 illustrates, in a perspective view, a second exemplary embodiment of a monolithically integrated combination of three MEMS projectors 11 R, G, B in a single component 13, which can, in particular, correspond to the component 13 from the embodiment of Fig. 5. This embodiment largely corresponds to that of Fig. 6, but with a compensation layer 17 arranged on the MEMS layer 15, which has at least one surface tilted relative to the stacking direction of the layers.In particular, the compensation layer 17 can have a gable roof shape on its outer side, in which the tilted surface forms a first roof surface 17a. The first roof surface 17a is tilted such that the radiation sources 12R, G, B are arranged on or in it and have an optical axis running orthogonal thereto. The second roof surface 17b of the gable roof shape, in turn, is tilted such that an optical axis (or central axis) of the radiation deflected (scanned) by the microscanners runs orthogonal to this second roof surface 17b. The second roof surface 17b is thus configured to be mounted in planar contact with a surface of the waveguide device 1 such that the scanned radiation from the microscanners can be radiated into the associated entrance pupil on this surface of the waveguide device 1.

[0072] Fig. 8 illustrates a perspective view of a third exemplary embodiment of a monolithically integrated combination of three MEMS projectors 11 R, G, B in a single component 13. Unlike in Fig. 7, the three MEMS projectors 11 R, G, B are not arranged in series here, but in a triangular configuration, in particular in the configuration of an equilateral triangle. The same applies accordingly to the associated radiation sources 12 R, G, B of the three MEMS projectors 11 R, G, B. The outer surface 17c serves here as a roof surface, which can in particular be flat and extend orthogonally to the stacking direction of the layers. It is configured to be mounted in contact with a surface of the waveguide device 1 in such a way that the scanned radiation of the microscanners can be radiated into the associated entrance pupil on this surface of the waveguide device 1.

[0073] The layered structure of the component 13, in particular according to Figure 7 or Figure 8, can in particular correspond to one of those described in detail in DE 10 2023 132 003.3, the content of which is incorporated herein in its entirety by reference.

[0074] Fig. 9 shows an exemplary embodiment of a handheld projector 18 (pico projector) whose size and weight are designed to be easily portable with one hand, similar to a mobile phone, headphones, a mini speaker, or other mobile electronic devices, particularly from the consumer electronics sector, and powered by an integrated battery. For example, its weight may be in the range of one kilogram, and its maximum dimensions may be in the range of 20 cm or less.

[0075] The handheld projector 18 contains, within a housing 20, an image projection device 2, which in its construction, at least fundamentally (i.e., at least except for a specific shape of the waveguide device 1), can correspond to one of the embodiments from Figures 1 to 3, in the present case, by way of example, that from Figure 2.

[0076] To serve as a polychromatic projection device, the image projection device 2 comprises the component 13, which in turn contains three different MEMS projectors 11R, 11G, and 11B, as described above. The component 13 is mechanically and optically coupled to the three-layer waveguide device 1 with three waveguides via the compensation layer 17. Corresponding to Fig. 2 (lower part of the figure), the coupling devices 4 of the various entrance pupils are also shown in Fig. 9.

[0077] The radiation guided by the waveguide device 1 exits the waveguide device 1 at least partially at the radiation exit surface 6 into the observation field 7, in which an imaging optics system, such as one or more lenses, can optionally be arranged to image the projected image emerging from the radiation exit surface 6. The polychromatic image projected by the handheld projector 18 (e.g., a single image or image sequence, in particular a video) can be directed, for example, onto a projection surface, such as a wall or a screen, or the like, to make it clearly visible to viewers.

[0078] List of reference symbols

[0079] 1 waveguide device

[0080] 1a right lens

[0081] 1b left lens

[0082] 2 Image projection device

[0083] 3 waveguides

[0084] 4 coupling device

[0085] 4R first entrance pupil

[0086] 4G second entrance pupil

[0087] 4B third entrance pupil

[0088] 5 Decoupling device

[0089] 6 Radiation exit surface

[0090] 7 Observation field

[0091] 8 replication facilities

[0092] 9B first "blue" ray path

[0093] 9G first "yellow" beam path

[0094] 9R first "red" ray path

[0095] 10B second "blue" ray path

[0096] 10G second "yellow" beam path

[0097] 10R second "red" beam path

[0098] 11R.GB MEMS projectors

[0099] 11 R first MEMS projector

[0100] 11G second MEMS projector

[0101] 11 B third MEMS projector

[0102] 12R.GB radiation source

[0103] 13 Component

[0104] 14 Basic substrate

[0105] 15 MEMS layer

[0106] 16 coupling tilt axis

[0107] 17 Leveling layer

[0108] 17a first roof area

[0109] 17b second roof area

[0110] 17c Roof area in Fig. 8

[0111] 18 Handheld Projector

[0112] 19 Imaging optics, especially lens

[0113] 20 housings

Claims

Patent claims 1 . Image projection device (2) for the polychromatic projection of an image into an observation field (7), wherein the image projection device (2) comprises: a plurality of MEMS projectors (11 R, G, B) for image projection by means of electromagnetic radiation, wherein the emission spectra of the radiation of the MEMS projectors (11 R, G, B) differ from one another in at least one wavelength range; and a waveguide device (1) for guiding the radiation emittable by the MEMS projectors (11 R, G, B), wherein the waveguide device (1) comprises: one or more waveguides (3); for each MEMS projector (11 R, G, B), a separate coupling device (4) for at least partially coupling the radiation emittable by the respective MEMS projector (11 R, G, B) into the respective MEMS projector(s).an associated one of the waveguides (3) such that the respective beam paths of the various MEMS projectors (11 R, G, B) in the waveguide device (1) run spatially separated from one another at least in sections; and at least one decoupling device (5) for each waveguide (3) for at least partially decoupling the radiation guided through the waveguide (3) into the observation field (7) located outside the waveguide device (1) such that the decoupled radiation of the various MEMS projectors (11 R, G, B) is superimposed in the observation field (7) to form a projected polychromatic overall image.

2. Image projection device (2) according to claim 1, wherein at least one of the MEMS projectors (11 R,G,B) is configured to emit monochromatic radiation.

3. Image projection device (2) according to claim 2, wherein the image projection device (2) has at least three monochromatic MEMS projectors (11 R, G, B), whose emission wavelengths are selected to be different such that together they span an at least three-dimensional color space, in particular according to the RGB color model.

4. Image projection device (2) according to one of the preceding claims, wherein the waveguide device (1) has a waveguide (3) which has a separate coupling device (4) for each MEMS projector (11R,G,B) for at least partially coupling the radiation emittable by the respective MEMS projector (11R,G,B) into the waveguide (3) in such a way that the respective emitted radiation beams of the various MEMS projectors (11R,G,B) run spatially separated from one another in the waveguide (3) at least in sections.

5. Image projection device (2) according to claim 4, wherein a replication device (8) for at least partially deflecting the beam is arranged in the beam path of at least one of the beams.

6. Image projection device (2) according to one of claims 1 to 3, wherein the waveguide device (1) has a plurality of waveguides (3), to each of which one of the MEMS projectors (11 R, G, B) is assigned such that its radiation can be coupled at least partially into a coupling device (4) of the respective waveguide (3), so that the respective beams of the various MEMS projectors (11 R, G, B) run through different waveguides (3) and thus at least partially spatially separated from one another.

7. Image projection device (2) according to claim 6, wherein the waveguides (3) are each formed as flat or curved plates and are arranged stacked one above the other as different layers of a stack.

8. Image projection device (2) according to one of the preceding claims, wherein the waveguiding device (3) is configured such that the radiation guided by it from at least two of the MEMS projectors (11R, G, B) exits the waveguiding device (3) at a radiation exit surface (6) common to this radiation on the surface of the waveguiding device (3).

9. Image projection device (2) according to one of the preceding claims, wherein at least one of the MEMS projectors (11R, G, B) has a microscanner as an imaging element for image projection.

10. Image projection device (2) according to claim 9, wherein the at least one MEMS projector (11R,G,B) with microscanner is configured to operate its microscanner as a Lissajous microscanner.

11. Image projection device (2) according to one of the preceding claims, wherein at least two of the MEMS projectors (11R,G,B) are designed as separate components.

12. Image projection device (2) according to one of claims 1 to 10, wherein at least two of the MEMS projectors (11R,G,B) are monolithically integrated in a common substrate.

13. Image projection device (2) according to claim 12, wherein the image projection device (2) comprises at least three MEMS projectors (11 R, G, B) which are monolithically integrated in the common substrate and are positioned in a row arrangement extending along a straight line.

14. Image projection device (2) according to claim 13 in combination with claim 9 or 10, wherein the straight line coincides with a virtual coupling-tilt axis or runs parallel thereto, so that in the MEMS projectors (11R, G, B) during their operation, radiation to be imaged by the associated microscanner is directed in a radial direction relative to the coupling-tilt axis onto a movable deflection element of the respective microscanner.

15. Image projection device (2) according to claim 12, wherein the image projection device (2) comprises at least three MEMS projectors (11 R, G, B) which are monolithically integrated in the common substrate and positioned in a triangular constellation.

16. Glasses, in particular XR glasses, comprising an image projection device (2) according to one of the preceding claims for the polychromatic projection of an image into a field of view overlapping with the observation field (7) of an observer wearing the glasses.

17. Handheld projector (18), comprising an image projection device (2) according to one of claims 1 to 15 for the polychromatic projection of an image onto a projection surface located in the observation field (7).

Images