Projection device for multi-field projection of images or information

Abstract

Projection device for projecting images and information, comprising at least two projectors (1 i ), each of which is used to scan at least one light beam (2 i ) are designed over a defined field angle, for multi-field projection from at least two light beams (2 i ), a waveguide (3) arranged so that the at least two light beams (2 i ) can be coupled into the waveguide (3), and at least as many coupling-out elements (31 i ), such as projectors (1 i ), wherein each coupling element (31 i ) by at least one projector (1 i ) and has a first and at least one second partial area, at least two pupil multipliers (4 i ) that is located between the projectors (1 i) and the waveguide (3) and are designed as amplitude splitter surfaces or as diffractive structures so that each light beam (2 i ) into a first partial light beam (2 i1 ) and at least a second partial light beam (2 i2 ), with the pupil multipliers (4 i ) are arranged so that each first partial light beam (2 i1 ) in the first partial area and every second partial light beam (2 i2 ) or further partial light beams (2 ii ) into the second or a further sub-area of each of the coupling elements (31 i ) to distract.

Description

Technical field of the invention

[0001] The invention relates to a projection device for multi-field projection of images and information, which can be used in particular in augmented reality applications.

[0002] Augmented reality (AR) refers to the computer-assisted extension of reality perception that addresses at least one of the human sensory modalities. However, AR is often understood to refer only to the visual representation of information, namely the supplementation of images or videos with computer-generated additional information and / or virtual objects by means of overlay or superimposition. In particular, the visual representation or projection of images, user interfaces, or information, such as directions, weather information, or news, is a common application of AR and is increasingly being used in so-called AR glasses, which can display images, user interfaces, or information directly on the user's lenses or retina.

[0003] A microscanner (also known as a micro-electro-mechanical system, or MEMS for short) can be used to project images or text information. A beam of light, generated by a light source located, for example, in the temple of an AR headset, is deflected onto the microscanner and then shaped. The light beam can then be scanned by the microscanner, creating an image in a field of view. Such an imaging system with a microscanner requires comparatively few optical elements, allowing for the creation of small and cost-effective projectors. State of the art

[0004] A microscanner is described, for example, in DE 10 2021 116 151 B3. The MEMS scanner disclosed therein can perform simultaneous rotational oscillations around two resonant oscillation axes in order to create a nonlinear Lissajous projection in an observation field by deflecting a light beam incident on a deflection element during the oscillations.

[0005] The oscillations scan a field of view (FOV) at high frequencies in a scan pattern resembling a Lissajous figure. Unlike conventional raster scanning methods, which periodically scan the FOV from top to bottom at maximum resolution, this allows hundreds of partial images to be processed simultaneously, enabling smoother motion representation. Furthermore, artifacts in the three-dimensional perception of fast-moving objects are greatly reduced.

[0006] In projection devices where the light beams emitted by projectors are coupled into a waveguide and guided by total internal reflection, the viewing field of the projection device, within which a user can perceive an image, is limited by the critical angle of total internal reflection. To enlarge the viewing field, a waveguide material with a high refractive index can be used for the waveguide, since the angular range of total internal reflection increases with increasing refractive index of the waveguide material. However, the use of materials with very high refractive indices is not suitable for mass production due to the high material costs. Description of the invention

[0007] It is therefore an object of the invention to provide a projection device for projecting images and information in which a viewing field is significantly enlarged and which can be manufactured cost-effectively. Furthermore, it is an object of the invention to provide augmented reality glasses containing a projection device with a significantly enlarged viewing field.

[0008] The object is achieved according to the invention by a projection device for projecting images and information, comprising at least two projectors, each designed to scan at least one light beam over a defined field angle, a waveguide arranged such that the at least two light beams can be coupled into the waveguide, and having at least as many output coupling elements as there are projectors for defined field angles, wherein each output coupling element is illuminated by at least one associated projector and has a first and at least one second partial area, at least two pupil multipliers arranged between the projectors and the waveguide and designed as amplitude splitter surfaces to reflect each light beam at least partially several times, or as diffractive structures to diffract each light beam partially several times,that each light beam is divided into a first partial light beam and at least one second partial light beam, wherein the pupil multipliers are arranged to deflect each first partial light beam into the first partial region and each second or further partial light beam into the second partial region or in each case a further partial region of one of the output coupling elements.

[0009] In the field of augmented reality, the term "field of view" refers to the visible area that the AR application or device overlays on the user's physical environment. The field of view is typically measured in degrees and can be specified horizontally, vertically, or diagonally. A larger field of view enables a more comprehensive integration of virtual elements into the physical world, creating a more immersive AR experience. It is often desirable to provide the largest possible field of view to optimize the user experience and minimize the boundaries between the real and virtual worlds.

[0010] Multi-field projection, as defined by the invention, is a technique in which an optical system, specifically a projection device, projects one or more images into multiple areas simultaneously. Multi-field projection makes it possible to significantly enlarge an observation field. Furthermore, it is possible to direct the light beams through the pupil multipliers and the output coupling elements in such a way that only a small portion, if any, of the light beams falls into an observation field that does not coincide with an eyebox or the user's field of vision. Thus, no or only a small portion of the light beams is lost during projection, and the projection efficiency of the projection device can be improved.

[0011] An advantage of using multiple projectors and multiple output windows is that a summary field angle, which results from all field angles of the individual projectors, is larger on one viewer side than the individual field angles of the projectors.

[0012] If only one projector is used, the total field angle is equal to the field angle of the projector. Thus, it is advantageous if the individual projector has the largest possible field angle. While this is technically feasible, the waveguide must then transmit the entire field angle range of the projector. If the light is guided in the waveguide by total internal reflection, which is often the case with inexpensive waveguides, the refractive index of the waveguide must be very high. This severely limits the degrees of freedom for other properties of the projection device, as there is little flexibility in both the waveguide material and the arrangement of the projector and waveguide.

[0013] Therefore, it is advantageous to use multiple projectors and multiple output ports: This results in greater flexibility in the selection of materials and the arrangement of the optical components of the projection device. This allows, for example, the weight of the projection device to be reduced and / or the compactness of the projection device to be increased, and more cost-effective projectors and waveguides can be used.

[0014] The projection angle ranges in which the partial light beams are scanned preferably have an overlap so that no boundaries are visible between the areas scanned by the partial light beams.

[0015] The waveguide is preferably substantially plate-shaped and made of a material through which the light beams emitted by the projectors can propagate. The light beams preferably propagate through the waveguide by total internal reflection at the outer sides of the waveguide. To this end, the light beams should preferably be coupled into the waveguide at an angle greater than the angle of total internal reflection. The angle of total internal reflection depends on the material from which the waveguide is made. The waveguide is preferably made of a material with a refractive index greater than 1.8. More preferably, the waveguide is made of a material with a refractive index greater than 2.0. The waveguide can consist of multiple layers or of just a single layer.The waveguide is advantageously a plate made of glass or plastic, for example, polymethyl methacrylate (PMMA), polycarbonate (PC), polystyrene (PS), or polyethylene terephthalate glycol (PETG). Particularly preferred is the lens of a pair of augmented reality glasses or the windshield of a motor vehicle. The waveguide can also be incorporated into any other medium.

[0016] The waveguide has several output coupling elements. The output coupling elements are preferably optical elements designed as output coupling gratings. Alternatively, the output coupling elements are also preferably prisms or mirrors integrated into the waveguide. The output coupling elements can also be designed to shape the respective light beams.

[0017] The output coupling elements, the pupil multipliers and the projectors are designed and arranged in such a way that each partial light beam is scanned at a specific projection angle after exiting the waveguide.

[0018] The waveguide can preferably also have multiple coupling elements. The coupling elements are essentially identical in structure to the output gratings and are designed to couple the light beams emitted by the projectors into the waveguide.

[0019] The pupil multiplier can increase the size of the exit pupil of the projection device. The pupil multiplier is a beam splitter or an arrangement of beam splitters that splits the light beam into several, preferably parallel, partial light beams. It can also be formed by diffractive structures that diffract the light beam. The diffractive structures can also be designed as holographic optical elements.

[0020] Advantageously, the output coupling elements, the pupil multipliers, and the projectors are designed and arranged such that the projection angles of the output coupling elements, at which the partial light beams are output from the output coupling elements, overlap within a predefined eyebox area (hereinafter also referred to as the "eyebox"). This reduces the proportion of the light beams that are normally lost and increases projection efficiency. The area around the eyebox is filled or illuminated asymmetrically. This means that not every point in the area around the eyebox is illuminated by the same number of light sources or projectors.

[0021] The projection angle is the angle at which the partial light beams are output from the output coupling elements. The field angle is the angle at which a light beam is emitted by a projector. Each projection angle is therefore determined by a field angle as well as the arrangement and design of the pupil multipliers, the waveguide, and the output coupling elements.

[0022] The "eyebox" is the area that receives light from all projection angles of the partial light beams. This is where an eye or pupil sees the entire image. If the eye is moved sideways out of the eyebox, it sees a shrinking portion of the image field, unlike a true exit pupil (e.g., in a microscope). If the area around the eyebox, in which part of the image field is still visible but which, by definition, no longer belongs to the eyebox, becomes smaller, the optical efficiency of the projection device can be improved, thus extending battery life.

[0023] Preferably, the partial light beams are not coupled out perpendicular to a surface of the waveguide and the projection angles are different from each other.

[0024] Preferably, each projector comprises at least one microscanner. The microscanner can, in particular, be embodied as a micro-electro-mechanical system (MEMS) and / or be designed to effect a nonlinear Lissajous projection into the observation field. The microscanner is configured to scan the light beam across the observation field, thereby generating an image on the observation field. By scanning the at least one light beam along a Lissajous figure, hundreds of partial images can be processed simultaneously, enabling a smoother representation of motion. Furthermore, artifacts in the user's three-dimensional perception of fast-moving objects are greatly reduced.

[0025] Preferably, there are as many pupil multipliers as projectors. Alternatively or additionally, there are just as many output coupling elements as projectors. If each projector is assigned exactly one pupil multiplier and one output coupling element, each pupil multiplier and each output coupling element can be tailored to the associated projector. Thus, the pupil multipliers and the output coupling elements can be tailored, for example, to the spectral range and / or the field angle of each projector, thereby reducing the requirements for the pupil multipliers and the output coupling elements while still achieving better imaging quality. There can also be more or fewer projectors and / or output coupling elements than projectors.

[0026] If the projection device comprises a microscanner, it can advantageously additionally comprise a sensor for detecting a viewing direction and a control unit. The microscanners are controlled by the control unit such that the partial light beams are each scanned only at a projection angle that corresponds to the user's viewing direction. Thus, the projection angle follows the viewing direction and areas not in the user's field of vision are not illuminated. This can save power and transmitted data bandwidth.

[0027] For the purposes of the invention, the direction of view refers to the orientation of a user’s head and eyes.

[0028] The projection device can preferably comprise a control unit and an evaluation unit, whereby the evaluation unit divides the information to be displayed into a first information group and at least one second information group, and the projectors are controlled by the control unit such that the information assigned to the first information group can be displayed with increased intensity and / or increased contrast. This allows light power to be saved for the information assigned to the second information group.

[0029] The object is further achieved by augmented reality glasses containing a projection device for multi-field projection of images and information according to one of the described embodiments. Short description of the drawings

[0030] The invention will be described in more detail below by means of exemplary embodiments based on drawings. Each index i represents an arbitrary natural number. These show: Fig. 1 A plan view of a first embodiment of a projection device for multi-field projection of images and information with three projectors, three pupil multipliers and three output coupling elements, Fig. 2 a plan view of a second embodiment of the projection device for multi-field projection of images and information with four projectors, four pupil multipliers and four output coupling elements, Fig. 3 a plan view of a third embodiment of the projection device for multi-field projection of images and information with four projectors, two pupil multipliers and four output coupling elements, Fig. 4A is a side view of a waveguide including decoupling elements of a projection device according to the prior art, Fig. 4B is a side view of a waveguide including output coupling elements of a fourth embodiment of the projection device for multi-field projection of images and information with three output coupling elements, Fig. 5 a side view of a waveguide including coupling elements of a fourth embodiment of the projection device for multi-field projection of images and information with five coupling elements as well as the intensities of the respective coupled partial light beams over the projection angles, and Fig. 6 a view of augmented reality glasses containing a projection device for multi-field projection of images and information. Detailed description of the drawings

[0031] A first embodiment of a projection device for multi-field projection of images and information is described in Fig. 1. The first embodiment of the projection device comprises three projectors 11, 12 and 13, each for scanning a light beam 2 i over a field angle. The projection device further comprises a waveguide 3, which is arranged such that the three light beams 21, 22 and 23 are coupled into the waveguide 3. The projection device has three output coupling elements 31 i where each decoupling element 31 i from the projector assigned to it 1 i illuminated and has three sub-areas (marked by dashed lines). Between the projectors 1 i and the waveguide 3 are three pupil multipliers 4 i arranged so that each light beam 2 i into three partial light beams 2 i1 , 2 i2 and 2 i3is divided.

[0032] Each pupil multiplier 4 i is designed so that each first partial light beam 2 i1 through the first pupil multiplier 41 into a first partial area, every second partial light beam 2 i2 through the pupil multiplier 42 into a second partial area and every third partial light beam 2i3 through the third pupil multiplier 43 into a third partial area of one of the output coupling elements 31 i is distracted.

[0033] In the first embodiment, the waveguide 3 has the shape of a lens of AR glasses. The projectors 11, 12, and 13, the output coupling elements 311, 312, and 313, and the pupil multipliers 41, 42, and 43 are each mounted in or on the waveguide 3.

[0034] Fig. Figure 2 shows a second embodiment of the projection device for multi-field projection of images and information. The second embodiment has four projectors 11-14, four pupil multipliers 41-44, and four output coupling elements 311-314. Each projector 1 i is a pupil multiplier 4 i assigned, whereby each pupil multiplier 4 i to the respective projector 1 i in terms of its properties and arrangement. This is particularly advantageous when the projectors 1 i Emit light in different wavelength ranges. In this case, aberrations can be corrected by adjusting each pupil multiplier 4 i to the wavelength range of the respective projector 1 i be minimized.

[0035] In the second version according to Fig. 2 and one in Fig. 3 shown design, each projector includes 1 iat least one microscanner configured as a microelectromechanical system (MEMS). The microscanners are depicted as circular or disc-shaped structures. Each microscanner is designed to produce a nonlinear Lissajous projection into an observation field. The projectors 1 i also include light sources (not shown) and components for beam guidance and shaping (also not shown).

[0036] The projection device further comprises a sensor 5 for detecting a viewing direction and a control unit 6. The microscanners can be controlled by the control unit 6 such that the (partial) light beams 2 i can only be scanned in one field or projection angle that corresponds to the viewing direction.

[0037] The second embodiment of the projection device also includes an evaluation unit 7. The evaluation unit 7 can divide the information to be displayed into a first information group and at least one second information group. The projectors 1 i can be controlled by the control unit 6 so that the information assigned to the first information group is displayed with increased intensity and / or increased contrast.

[0038] Fig. Figure 3 shows a third embodiment of the projection device for multi-field projection of images and information. This embodiment has four projectors 11-14, two pupil multipliers 41 and 42, and four output coupling elements 311-314. Two projectors 1 i is a pupil multiplier 4 iSince there are only two pupil multipliers 41 and 42, the assembly and adjustment effort is reduced compared to the second version. In return, the requirements for the pupil multipliers 4 i increased.

[0039] In the state of the art, it is common that all decoupling elements 31 i and projectors 1 i are arranged so that each of the coupling elements 31 i has the same coupling behavior. A waveguide 3 including coupling elements 31 i a projection device according to the state of the art shows, for example, Fig. 4A. The partial light beams 2 ii are coupled out essentially perpendicular to a surface O of the waveguide 3 (thick arrows represent a mean coupling-out direction of each coupling-out element 31 i ), whereby the partial light beams 2 iiremain at least partially unused, since in particular the marginal rays (shown in dashed lines) do not contribute to the image or projection.

[0040] In Fig. 4B is a waveguide 3 including decoupling elements 31 i according to a fourth embodiment of the projection device for multi-field projection of images and information with three output coupling elements 311-313.

[0041] In the fourth version, the decoupling elements 31 i , the pupil multipliers 4 i and the projectors 1 i designed and arranged so that the projection angle β i the projectors 1 i , under which the partial light beams 2 ii from the decoupling elements 31 i are decoupled, superimposed in a given eyebox area E.

[0042] In addition, the partial light beams 2 iinot perpendicular to a surface O of the waveguide 3 and the projection angles β i the partial light beam 2 ii are different from each other. The partial light beams 2 ii are directed as far as possible towards the eyebox E from the output elements 31 i decoupled.

[0043] A waveguide 3 including coupling elements 31 i shows Fig. 5 in a fourth embodiment of the projection device for multi-field projection of images and information with five output elements 311-315. In Fig. 5 are also the intensities I i the respective decoupled partial light beams 2 ii over the projection angles βi. The resulting intensities I i resulting total intensity I ges is also shown (in a thicker line). It results for each point from the sum of the individual intensities I i .

[0044] Waveguides 3, especially diffractive ones, often have problems with the uniformity of the (multi-colored) projection, since a single waveguide 3 often guides light of different wavelength ranges, which results in aberrations and reduces image quality. Field stitching, as used in Fig. As shown schematically in Figure 5, the image quality during projection can be improved. Field stitching refers to a process in which multiple partial images or partial observation fields are seamlessly combined into a single observation field or overall image. The purpose of fieldstitching is to achieve a larger observation field without sacrificing detail.

[0045] Augmented reality glasses containing a projection device for multi-field projection of images and information show Fig.6. A waveguide 3 is integrated into each lens of the AR glasses, which has four output coupling elements 311-314. The partial light beams 2 ii are from the decoupling elements 31 i towards the eyes of a user, i.e. towards the temples of the AR glasses. List of reference symbols 1 i projector 2 i beam of light 2 ii Partial light beam 3 waveguides 31 i Decoupling element 4 i Pupil multiplier 5 Sensor 6 Control unit 7 Evaluation unit β i Projection angle I i intensity I ges Total intensity E Eyebox(-area) O Surface QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] DE 10 2021 116 151 B3

[0004]

Claims

[1] Projection device for projecting images and information, comprising: - at least two projectors (1 i ), each of which is used to scan at least one light beam (2 i ) are designed over a defined field angle to enable multi-field projection with at least two projectors (1 i ) scanned at least two light beams (2 i ) to generate - a waveguide (3) arranged so that the at least two light beams (2 i ) can be coupled into the waveguide (3), and at least as many coupling-out elements (31 i ), such as projectors (1 i ) for defined field angles, whereby each coupling element (31 i ) by at least one projector (1 i ) is illuminated and has a first and at least one second partial area, - at least two pupil multipliers (4 i) that is located between the projectors (1 i ) and the waveguide (3) and as amplitude splitter surfaces to each light beam (2 i ) to reflect and transmit several times proportionally, or as diffractive structures to separate each light beam (2 i ) to diffract several times proportionally, are designed so that each light beam (2 i ) into a first partial light beam (2 i1 ) and at least a second partial light beam (2 i2 ) is divided, - where the pupil multipliers (4 i ) are arranged so that each first partial light beam (2 i1 ) in the first partial area and every second partial light beam (2 i2 ) or further partial light beams (2 ii ) into the second sub-area or a further sub-area of one of the coupling-out elements (31 i ) to distract. [2] Projection device according to claim 1, wherein the coupling-out elements (31 i), the pupil multipliers (4 i ) and the projectors (1 i ) are designed and arranged so that the projection angle (β i ) of the decoupling elements (31 i ), under which the partial light beams (2 ii ) from the decoupling elements (31 i ) are overlaid in a given eyebox area (E). [3] Projection device according to claim 2, wherein the partial light beams (2 ii ) are coupled out essentially obliquely to a surface (O) of the waveguide (3) and the projection angles (β i ) the partial light beams (2 ii ) are different from each other. [4] Projection device according to one of claims 1 to 3, wherein each projector (1 i ) comprises at least one microscanner designed as a micro-electromechanical system (MEMS). [5] Projection device according to claim 4, wherein each microscanner is adapted to effect a non-linear Lissajous projection into an observation field. [6] Projection device according to one of claims 1 to 5, wherein as many pupil multipliers (4 i ) such as projectors (1 i ) are present. [7] Projection device according to one of claims 1 to 6, wherein as many coupling-out elements (31 i ) such as projectors (1 i ) are present. [8] Projection device according to one of claims 4 to 7, wherein the projection device comprises a sensor (5) for detecting a viewing direction and a control unit (6), and the microscanners (by the control unit (6) are controlled such that the partial light beams (2 ii ) only in one projection angle (β i ) corresponding to the direction of view. [9] Projection device according to one of claims 1 to 8, wherein the projection device comprises a control unit (6) and an evaluation unit (7), whereby information to be displayed can be divided by the evaluation unit (7) into a first information group and at least one second information group and the projectors (1 i ) can be controlled by the control unit (6) in such a way that the information assigned to the first information group can be displayed with increased intensity and / or increased contrast. [10] Projection device according to one of claims 1 to 9, wherein the waveguide (3) is formed of plastic. [11] Augmented reality glasses containing a projection device for multi-field projection of images and information according to one of claims 1 to 10.

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