Projection device for multifield projection of images and information

Abstract

The invention relates to a projection device for projecting images and information, comprising at least two projectors (1i) for multifield projection from at least two light beams (2i), a waveguide (3), into which the at least two light beams (2i) can be coupled, and which has at least as many decoupling elements (31i) with first and second sub-regions as there are projectors (1i), also comprising at least two pupil multipliers (4i), which are arranged between the projectors (1i) and the waveguide (3) and divide each light beam (2i) into a first partial light beam (2i1) and at least one second partial light beam (2i2), wherein the pupil multipliers (4i) deflect each first partial light beam (2i1) into the first sub-region and each second partial light beam (2i2) or further partial light beams (2ii) into the second or a further sub-region of each of the decoupling elements (31i).

Description

title Projection device for multi-field projection of images and information Technical field of

[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 rotary oscillations around two resonant oscillation axes in order to to cause a nonlinear Lissajous projection in an observation field of a light beam incident on a deflection element.

[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 through total resection within the waveguide, 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 so 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, which are arranged between the projectors and the waveguide and are designed as amplitude splitter surfaces in order to reflect each light beam at least partially several times, or as diffractive structures in order to diffract each light beam several times, in such a way 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 designed to deflect each first partial light beam into the first partial area and each second or further partial light beam into the second partial area or in each case a further partial area 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. Therefore, it is advantageous if the individual projector has the largest possible field angle. While this is technically feasible, the waveguide must transmit the entire field angle range of the projector in this case. If the light in the waveguide is guided by total internal reflection, which is possible with inexpensive waveguides, As is often the case, 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 resection on the outer sides of the waveguide. For this purpose, the light beams should preferably be coupled into the waveguide at an angle that is 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 several 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 one 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 information to be displayed is divided by the evaluation unit 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 contrast. This allows light output 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. Show this: 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 is 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 is 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 coupling 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 is 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 is 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 shown in Fig. 1. The first embodiment of the projection device comprises three projectors 11, 12, and 13, each of which is designed to scan a light beam 2i over a field angle. The projection device further comprises a waveguide 3, which is arranged such that the three light beams 2i, 22, and 23 are coupled into the waveguide 3. The projection device has three output coupling elements 31i, each output coupling element 31i being illuminated by its associated projector T and having three partial regions (indicated by dashed lines). Three pupil multipliers 4i are arranged between the projectors 1i and the waveguide 3 such that each light beam 2i is divided into three partial light beams 2H, 2 i2 and 2 i3 is divided.

[0032] Each pupil multiplier 4i is designed such that each first partial light beam 2n is deflected by the first pupil multiplier 4i into a first partial area, each second partial light beam 2i2 is deflected by the pupil multiplier 42 into a second partial area, and each third partial light beam 2i3 is deflected by the third pupil multiplier 43 into a third partial area of one of the output coupling elements 31i.

[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. 2 shows a second embodiment of the projection device for multi-field projection of images and information. The second embodiment has four projectors I 1 - I 4 , four pupil multipliers 4 I - 4 , and four output coupling elements 31 1 - 31 4 . Each projector 1 i is assigned a pupil multiplier 4 i , whereby each pupil multiplier 4 i can be tailored to the respective projector T in terms of its properties and arrangement. This is particularly advantageous when the projectors T emit light in different wavelength ranges. In this case, imaging errors can be minimized by adapting each pupil multiplier 4 i to the wavelength range of the respective projector 1 i .

[0035] In the second embodiment according to Fig. 2 and a configuration shown in Fig. 3, each projector T comprises at least one microscanner embodied 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 T also comprise 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 2i are each scanned only in a 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 T can be controlled by the control unit 6 such that the information assigned to the first information group is displayed with increased intensity and / or increased contrast.

[0038] Fig. 3 shows a third embodiment of the projection device for multi-field projection of images and information. This embodiment has four projectors I1-I4, two pupil multipliers 4i and 42, and four output coupling elements 311-314. Each two projectors Ii are assigned a pupil multiplier 4i. Since only two pupil multipliers 4i and 42 are present, assembly and adjustment effort is reduced compared to the second embodiment. However, the requirements for the pupil multipliers 4i are increased.

[0039] In the prior art, it is common for all output coupling elements 31 i and projectors 1 i to be arranged such that each of the output coupling elements 31 i exhibits the same output coupling behavior. Fig. 4A shows, by way of example, a waveguide 3 together with output coupling elements 31 i of a projection device according to the prior art. The partial light beams 2 » are outputted essentially perpendicularly to a surface O of the waveguide 3 (thick arrows represent a mean output coupling direction of each output coupling element 31 i), whereby the partial light beams 2Ü remain at least partially unused, since in particular the edge rays (shown in dashed lines) do not contribute to the imaging or projection.

[0040] Fig. 4B shows a waveguide 3 together with output coupling elements 31i 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 embodiment, the output coupling elements 31 i, the pupil multipliers 4 i and the projectors T are designed and arranged such that projection angles ßi of the projectors T, at which the partial light beams 2» are output from the output coupling elements 31 i, overlap in a predetermined eyebox area E.

[0042] Furthermore, the partial light beams 2Ü are not coupled out perpendicularly to a surface O of the waveguide 3, and the projection angles ßi of the partial light beams 2» are different from one another. The partial light beams 2» are coupled out of the coupling elements 31i in the direction of the eyebox E, if possible.

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

[0044] Waveguides 3, especially diffractive ones, often have problems with the uniformity of the (multicolor) projection, since a single waveguide 3 often guides light of different wavelength ranges, resulting in aberrations and reducing image quality. Field stitching, as schematically shown in Fig. 5, can improve image quality during projection. Field stitching refers to a process in which multiple partial images or partial observation fields are seamlessly combined to form a single observation field or an overall image. The purpose of field stitching is to achieve a larger observation field without sacrificing detail.

[0045] Fig. 6 shows a pair of augmented reality glasses containing a projection device for multi-field projection of images and information. A waveguide 3 is integrated into each lens of the AR glasses, which has four output coupling elements 311-314. The partial light beams 2Ü are output by the output coupling elements 31i toward the eyes of a user, i.e., toward the temples of the AR glasses. List of reference symbols 1i projector 2i light beams 2Ü Partial light beam 3 waveguides 31 i Decoupling element 4i Pupil Multiplier 5 Sensor 6 Control unit 7 Evaluation unit ßi Projection angle li Intensity Total intensity E Eyebox(-area) O Surface

Claims

1. Projection device for projecting images and information, comprising: - at least two projectors (1 i), each designed to scan at least one light beam (2i) over a defined field angle in order to generate a multi-field projection with at least two light beams (2i) scanned by the at least two projectors (T), - a waveguide (3) which is arranged such that the at least two light beams (2i) can be coupled into the waveguide (3), and has at least as many output coupling elements (31i) as there are projectors (T) for defined field angles, wherein each output coupling element (31i) is illuminated by at least one projector (T) assigned to it and has a first and at least one second partial area, - at least two pupil multipliers (4i) which are arranged between the projectors (T) and the waveguide (3) and are designed as amplitude splitter surfaces in order to reflect and transmit each light beam (2i) several times in proportion, or as diffractive structures in order to diffract each light beam (2i) several times in proportion, such that each light beam (2i) is divided into a first partial light beam (2ii) and at least one second partial light beam (2 i2 ) is divided, - wherein the pupil multipliers (4i) are arranged to deflect each first partial light beam (2ii) into the first partial area and each second partial light beam (2i2) or further partial light beams (2Ü) into the second partial area or a further partial area of one of the output coupling elements (31i).

2. Projection device according to claim 1, wherein the coupling-out elements (31 i), the pupil multipliers (4 i) and the projectors (T) are designed and arranged such that projection angles (ßi) of the coupling-out elements (31 i), at which the partial light beams (2Ü) are coupled out of the coupling-out elements (31 i), overlap in a predetermined eyebox area (E).

3. Projection device according to claim 2, wherein the partial light beams (2Ü) are coupled out substantially obliquely to a surface (O) of the waveguide (3) and the projection angles (ßi) of the partial light beams (2Ü) are different from one another.

4. Projection device according to one of claims 1 to 3, wherein each projector (1 j) comprises at least one microscanner which is designed as a micro-electromechanical system (MEMS).

5. Projection device according to claim 4, wherein each microscanner is configured to effect a nonlinear Lissajous projection into an observation field.

6. Projection device according to one of claims 1 to 5, wherein there are as many pupil multipliers (4i) as projectors (1j).

7. Projection device according to one of claims 1 to 6, wherein there are as many output coupling elements (31 i) as projectors (1 j).

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 are controlled by the control unit (6) such that the partial light beams (2Ü) are each scanned only at a projection angle (ßi) which corresponds to the viewing direction.

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 (T) can be controlled by the control unit (6) such that the information which has been 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 from 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.

Images