Optical arrangement, head-up display and ar / VR-glasses

Abstract

An Optical arrangement is specified, comprising - a projector (1) which is configured to generate an image (2), - a waveguide (3) which is configured to receive the image (2) form the projector (1), and - a holographic element (4), which is configured to receive the image (2) from the waveguide (3) and to overlay the image (2), wherein - the waveguide (3) comprises an entrance region (3a) for receiving the image (2) from the projector (1), an exit region (3c) for relaying the image (2) to the holographic element (4), and at least one reflective surface (3b) for relaying the image (2) from the entrance region (3a) to the exit region (3c). The projector for example may comprise laser diodes or a micro-LED panel or a LCoS panel for image generation.

Description

[0001] Description

[0002] OPTICAL ARRANGEMENT, HEAD-UP DISPLAY AND AR / VR-GLASSES

[0003] An optical arrangement is specified.

[0004] One object to be solved is to specify an optical arrangement which is particularly compact in size.

[0005] Document US 20200371282 describes an optical arrangement and is herewith included by reference.

[0006] According to at least one aspect of the optical arrangement, the optical arrangement comprises a projector. The projector is configured to generate an image. For this the projector comprises at least one optoelectronic device which is configured to generate visible light during operation. For example, the projector is configured to generate a monochromatic or a polychromatic image.

[0007] For example the at least one optoelectronic device generates light, e.g. colored light like blue, red and green light.

[0008] This visible light is combined to form the image, e.g. by a scanning method.

[0009] In particular, the projector is configured to dynamically generate images, e.g. animated images or a sequence of images as, for example, a video clip.

[0010] According to at least one aspect of the optical arrangement, the optical arrangement comprises a waveguide which is configured to receive the image from the projector. For example , the light forming the image is coupled into the waveguide at an entrance region of the waveguide . For this , the proj ector can be arranged in the vicinity of the waveguide . Thereby it is also possible that an outer surface of the proj ector and an outer surface of the waveguide are optically coupled to each other or in direct contact with each other .

[0011] According to at least one aspect of the optical arrangement , the optical arrangement comprises a holographic element which is configured to receive the image , e . g . the light which forms the image , from the waveguide and to overlay the image .

[0012] For example , the holographic element is reflecting the light which is received from the waveguide into an eye or the eyes of a user of the optical arrangement and thereby the image is overlaid, for example , to the outside world or another image .

[0013] According to at least one aspect of the optical arrangement , the waveguide comprises the entrance region for receiving the image , e . g . the light forming the image , from the proj ector, an exit region for relaying the image to the holographic element and at least one reflective surface for relaying the image from the entrance region to the exit region .

[0014] For example , the image is relayed by the waveguide from the entrance region to the exit region by total internal reflection of the light which forms the image . Alternatively or additionally the at least one reflective surface of the waveguide can be coated with a reflective material , e . g . a metallic film in order to reflect the light . The holographic element is arranged in the vicinity of the exit region of the waveguide such that the image can be directly relayed to the holographic element or via an optical element arranged between the waveguide and the holographic element .

[0015] According to at least one aspect of the optical arrangement , the optical arrangement comprises : a proj ector which is configured to generate an image , a waveguide which is configured to receive the image form the proj ector, and a holographic element , which is configured to receive the image from the waveguide and to overlay the image , wherein the waveguide comprises an entrance region for receiving the image from the proj ector, an exit region for relaying the image to the holographic element , and at least one reflective surface for relaying the image from the entrance region to the exit region .

[0016] Here , an optical arrangement is speci fied . In particular an imaging relay waveguide for use with a holographic element like e . g . a holographic combiners is speci fied .

[0017] The optical arrangement can inter alia be used in augmented reality and / or virtual reality applications .

[0018] Holographic elements used for augmented reality systems require an optical system to pro j ect / relay the image information onto a holographic plane / combiner . This proj ection may happen in free space from a proj ector that may be located on the leg / arm of a pair of glasses , onto the holographic plane located on the lens of the glasses .

[0019] This type of system can be bulky and the optical path can be obstructed by the user' s facial features and hair . As every user has a di f ferent shaped face and head, it can be di f ficult to determine a suitable location for the proj ector to sit on the frame of the glasses that can suit every user, where the image can be ef ficiently directed towards the holographic plane / combiner , i . e . the holographic element .

[0020] The here described optical arrangement inter alia relies on the idea that by using a waveguide the image can be relayed from the proj ector to the holographic element without interference form otherwise disturbing factors like facial features of the user, hair of the user, type of glasses and so on .

[0021] According to at least one aspect of the optical arrangement , the waveguide is wedge-shaped, at least in parts . Thereby, it is possible that the waveguide has the shape of a wedge partly or completely . That is to say, the waveguide has , for example , at least two reflective plane surfaces which are not arranged in parallel with each other at least in places . Such a wedge-shaped waveguide can be produced rather cost- ef fectively and has a rather small lateral extension .

[0022] Concerning the wedge-shape of the waveguide , it is possible that a lateral extension of the waveguide is larger at the entrance region or close to the entrance region, e . g . in a region close to the proj ector than at the exit region or close to the exit region of the waveguide . Further, the lateral extension of the waveguide may decrease , for instance steadily or constantly, in a direction from the entrance region to the exit region . This direction, from the entrance region to the exit region, may be a vertical direction which runs perpendicular or at least oblique to the lateral direction .

[0023] According to at least one aspect of the optical arrangement , at least one of the at least one reflective surfaces of the waveguide is curved, at least in parts . For example , all reflective surfaces of the waveguide can be curved . Further, it is possible that a partly wedge-shaped waveguide is combined with a partly curved waveguide . Such waveguides with curved surfaces may be more di f ficult to produce than completely wedge-shaped waveguides , however they may display fewer optical aberrations during relaying the image .

[0024] According to at least one aspect of the optical arrangement , a first optical element is arranged between the proj ector and the entrance region of the waveguide .

[0025] The optical element forms the light received from the proj ector for entrance into the waveguide , for example such that the condition for total internal reflection of the light at the reflective surfaces of the waveguide can be better met .

[0026] For example , the first optical element can have a prismatic shape and / or comprise a lens . Thereby, it is possible that the first optical element and the waveguide are in direct contact with each other or are formed in one piece with each other . Such an optical element is particularly ef fective when combined with a wedge-shaped waveguide . According to at least one aspect of the optical arrangement , the arrangement comprises a second optical element which is arranged between the exit region of the waveguide and the holographic element . For example , the second optical element can have a prismatic shape and / or comprise a lens .

[0027] Also the second optical element can be in direct contact with the waveguide or can be formed in one piece with the waveguide .

[0028] Such a second optical element is particularly advantageous in combination with a wedge-shaped waveguide for forming the light at the exit region for a correct display of the image onto the holographic element .

[0029] According to at least one aspect of the optical arrangement the holographic element comprises a holographic combiner and / or a holographic optical element .

[0030] A holographic combiner is for example formed via a semitransparent surface which is used to overlay the image presented by the proj ector on top of the viewer' s physical world or another image .

[0031] For example , the combiner is transparent , enabling the viewer to see through it while simultaneously reflecting the dynamic digital information given by the image at the holographic plane of the holographic combiner . For example , the combiner can be formed with a flat piece of a transparent material that redirects the image using, for example , Fresnel reflection which is the result of an index di f ference between the transparent material and the surrounding air . A holographic optical element is a thin optical element that uses the principle of di f fraction to trans form an incident wavefront from the image into another predefined wavefront . Such a holographic optical element can also be made to act as a lens on curved surfaces . Other than the holographic combiner, the holographic optical element can be applied on curved surfaces .

[0032] According to at least one aspect of the optical arrangement the proj ector comprises at least one laser diode as an optoelectronic component for generating the image .

[0033] Alternatively, it is also possible that the image is generated using a Liquid Crystal on Silicon ( LCoS ) panel or a micro-LED panel that generates the image . In such a micro-LED panel single pixels or subpixels of the image can be generated by Micro LEDs .

[0034] As a broad definition, a micro-LED could be seen as any light emitting diode ( LED) - generally not a laser - with a particularly small si ze .

[0035] As a rule - and this is a very important criterion in addition to si ze - a growth substrate is removed from microLEDs , so that typical heights of such micro-LEDs are in the range of 1 . 5 pm to 10 pm, for example .

[0036] In principle , a micro-LED does not necessarily have to have a rectangular radiation emission surface . Generally, for example , an LED could have a radiation emission surface in which, in plan view of the layers of the layer stack, any lateral extent of the radiation emission surface is less than or equal to 100 qm or less than or equal to 70 qm .

[0037] For example , in the case of rectangular micro-LEDs , an edge length - especially in plan view of the layers of the layer stack - smaller than or equal to 70 qm or smaller than or equal to 50 qm is possible .

[0038] Mostly, such micro-LEDs are provided on wafers with - for the qLED non-destructively - detachable holding structures .

[0039] At present , micro-LEDs are mainly used in displays . The micro-LEDs form pixels or subpixels and emit light of a defined color . Small pixel si ze and a high density with close distances make micro-LEDs suitable , among others , for small monolithic displays for AR applications , especially data glasses . In addition, other applications are being developed, in particular regarding the use in data communication or pixelated lighting applications .

[0040] Di f ferent ways of spelling micro-LED, e . g . qLED, q-LED, uLED, u-LED or micro light emitting diode can be found in the relevant literature .

[0041] For example , the proj ector is configured to produce red, green and blue light by using one or more laser diodes or micro-LEDs .

[0042] The radiation emitted by the laser diodes , for example , forms the image by a scanning method and the laser radiation is directed via the waveguide onto the holographic optical element . According to at least one aspect of the optical arrangement the image is reflected directly from the holographic element into the eye of a viewer . This means that between the eye of the viewer and the holographic element , for example , there is no other waveguide and no other optical element . This allows for a particularly compact optical arrangement .

[0043] Further, a head-up display is speci fied . The here-speci fied head-up display comprises the here-described optical arrangement . That is to say, all features disclosed for the optical arrangement are also disclosed for the head-up display .

[0044] Further, the head-up display comprises a windscreen or a window pane wherein the holographic element of the optical arrangement is arranged on or into the windscreen or the window pane . For example , the head-up display can be integrated into the windscreen of a vehicle . From the windscreen or the window pane the image relayed to the holographic element is reflected into the eye of the user .

[0045] Further, AR ( augmented reality) and / or VR (Virtual Reality) glasses are speci fied which comprise a here-described optical arrangement . That is to say, all features disclosed for the optical arrangement are also disclosed for the AR / VR glasses .

[0046] Further, the glasses comprise a frame and at least one glass , e . g . a lens of the glasses . The proj ector is attached to the frame , e . g . to or into the leg or arm of the glasses .

[0047] The holographic optical element is arranged on or into the at least one glass . A here-described optical arrangement is particularly suited for such glasses as the arrangement is particularly compact in si ze and has a low weight .

[0048] According to at least one aspect of the AR / VR glasses , the at least one glass is translucent or switchable translucent . In the case that glass is switchable translucent it can be switched into an opaque , for example reflective , state . In such a way the AR glasses can be used as VR glasses .

[0049] Further advantageous embodiments and further embodiments of the herein described optical arrangement , the herein described head-up display and the herein described AR / VR- glasses become apparent from the following exemplary embodiments described in connection with the figures .

[0050] Figure 1 shows an exemplary embodiment of a here-described optical arrangement in a schematic sectional view .

[0051] Figure 2 shows a further exemplary embodiment of a here- described optical arrangement in a schematic sectional view .

[0052] Figure 3 shows an exemplary embodiment of here-described AR / VR glasses in a schematic spatial representation .

[0053] Figure 4 shows a further exemplary embodiment of here- described AR / VR glasses in a schematic spatial representation .

[0054] Figure 5 shows a schematic spatial representation of AR / VR glasses for describing the advantages of the here-described AR / VR glasses . Figure 6 shows a schematic spatial representation of an exemplary embodiment of a here-described head-up display .

[0055] In the exemplary embodiments and figures , identical , similar or identically acting elements are provided in each case with the same reference numerals . The elements illustrated and their si ze ratios to one another should not be regarded as being to scale , but rather individual elements , such as for example elements , components , devices and regions , may have been made exaggeratedly large to illustrate them better and / or to aid comprehension .

[0056] Figure 1 shows a schematic sectional view of an embodiment of a here-described optical arrangement . The optical arrangement comprises a proj ector 1 which is configured to generate an image 2 . For example , the proj ector 1 comprises a blue lightemitting laser diode IB, a red light-emitting laser diode 1R and a green light-emitting laser diode 1G . The laser diodes 1R, IB, 1C emit red, blue and green light during operation which forms the image 2 . Further, the proj ector 1 may comprise a MEMS device after the laser diodes 1R, IB, 1C . As an alternative the proj ector may comprise a micro-LED panel or LCoS panel for image generation .

[0057] Further, the optical arrangement comprises a waveguide 3 which is configured to receive the image 2 from the proj ector 1 .

[0058] The waveguide 3 comprises an entrance region 3a for receiving the image 2 from the proj ector 1 , an exit region 3c for relaying the image 2 to a holographic element 4 . The holographic element 4 is configured to receive the image 2 from the waveguide 3 and to overlay the image 2 , for example to the viewer' s view .

[0059] In the embodiment of Figure 1 the waveguide 3 is wedge- shaped . The waveguide comprises reflective surfaces 3b for which two reflective surfaces 3b which are arranged opposite to each other are arranged non-parallel with each other . The reflective surfaces 3b relay the image 2 from the entrance region 3a to the exit region 3c, for example by total internal reflection .

[0060] The optical arrangement further comprises a first optical element 5 between the proj ector 1 and the entrance region 3a of the waveguide 3 . The first optical element 5 and the waveguide 3 are in direct contact with each other or formed from one piece .

[0061] Further, the optical arrangement comprises a second optical element 6 which is arranged between the exit region 3c of the waveguide 3 and the holographic element 4 and which also can be in direct contact with the waveguide 3 or formed in one piece with the waveguide 3 . Advantageously, a lateral extension L of the optical arrangement with such a wedge- shaped waveguide can be rather small , for example the lateral extension can be 15 mm or less or 10 mm or less .

[0062] The first optical element 5 and / or the second optical element 6 may comprise a triangular shape in cross-section . In this way the optical elements are particularly easy to produce .

[0063] The holographic element 4 , e . g . comprises a holographic combiner . A holographic combiner comprises a semi-transparent surface that allows the viewer to see through it while reflecting dynamic digital information, the image 2 .

[0064] The proj ector 1 creates the image 2 that is superimposed on the outside world through the semi-transparent surface of the holographic element .

[0065] To increase the visibility of the image and make it more comfortable to see in daylight , the reflection from the semitransparent surface can be enhanced with a reflective coating on one side of the semi-transparent surface .

[0066] Alternatively, the holographic element 4 e . g . comprises a holographic optical element . A holographic optical element is a thin optical element that uses the principle of di f fraction to trans form an incident wavefront from the image into another predefined wavefront . Such a holographic optical element can also be made to act as a lens and can be applied on curved surfaces .

[0067] Here the use of a waveguide to relay the image from a proj ector exit to the hologram is proposed . The waveguides 3 presented here are shaped both in the forms of a 'wedge ' and / or a ' curve ' .

[0068] The wedge waveguide of figure 1 has added benefits for the image quality preservation . The curved waveguide of figure 2 mostly benefits the space reduction and adds flexibility in placing the proj ector . This may be beneficial when proj ectors need to be fitted onto variously designed frames . This can reduce the form factor considerably by bringing the projector further forward onto a frame of a pair of glasses, almost to the same plane as the hologram.

[0069] In simple terms, a waveguide 3 is used to relay a signal from one position / pro ector to another position / pupil through a medium. In this case, the signal is actually the image 2. The positions, which shall now be called entrance region 3a and exit region 3b, are for AR / VR glasses e.g. from the edge of the glasses where a projector could be placed on the arm of the frame (entrance) , to the lens of the glasses where a hologram will have been affixed either through lamination, embedding in a sandwich layer or some other form of fixation to the surface of the lens (exit) .

[0070] The medium, i.e. the material with which the waveguide is formed can be a polymer or glass which must have a refractive index (RI) change at the boundary / interf ace between the waveguide 3 and its neighboring material. The waveguide 3 uses total-internal-reflection (TIR) to achieve this propagation of the signal. The TIR condition is met when the incident angle within the medium is equal to or greater than the critical angle of said medium which can be calculated from the following equation: 0C = arcsin (n2 / nl ) , where 0C is the critical angle, nl is the RI of the medium in which the ray begins, and n2 is the RI of the medium at the interface of medium, e.g. the RI of the surrounding air.

[0071] The additional components here would be the waveguide itself, and the 'in' and 'out' coupling optics. The 'in' and 'out' coupling optics 5, 6 are vital to preserve the image quality that may be affected when travelling through the waveguide 3. They will also set the conditions for the TIR to take place most ef ficiently by defining and limiting the angle of incidence into the waveguide 3 .

[0072] Figure 2 shows a schematic sectional view of a further embodiment of a here-described optical arrangement . In this embodiment the at least one reflective surface 3b of the waveguide 3 is curved . This allows for fewer optical aberrations , even without the use of first and second optical 5 , 6 elements . For example such an optical arrangement can be free of any optical elements between the proj ector 1 and the waveguide 3 and between the waveguide and the holographic element . However, the lateral extension L of such an optical arrangement may be greater than the lateral extension of the arrangement according to the embodiment of Figure 1 . For example , the lateral extension is 25 mm or less or 20 mm or less .

[0073] Also in the embodiment of figure 2 a waveguide 3 is used to relay a signal from one position / pro ector to another position / pupil through a medium . In this case , the signal is actually the image 2 . The positions , which shall now be called entrance region 3a and exit region 3c, are in case of AR / VR glasses from the edge of the glasses where a proj ector 1 could be placed on the arm of the frame ( entrance ) , to the lens of the glasses where a hologram will have been af fixed either through lamination, embedding in a sandwich layer or some other form of fixation to the surface of the lens ( exit ) .

[0074] The medium of the waveguide 3 can be a polymer or glass which must have refractive index (RI ) change at the boundary / interf ace between the waveguide and its neighboring material . The waveguide 3 uses total-internal-reflection (TIR) to achieve this propagation of the signal. The TIR condition is met when the incident angle within the medium is equal to or greater than the critical angle of said medium which can be calculated form the following equation: 0C = arcsin (n2 / nl ) , where 0C is the critical angle, nl is the RI of the medium in which the ray begins, and n2 is the RI of the medium at the interface of medium e.g. the RI of the surrounding air.

[0075] The schematic spatial view of Figure 3 shows a first embodiment of here-described AR / VR glasses. The AR / VR glasses comprise an optical arrangement according to the embodiment of Figure 1 with an at least partly wedge-shaped waveguide 3. The projector 1 is attached to a frame 10, e.g. the arm or leg of the frame 10 of the glasses and the holographic element 4, for example a holographic combiner or a holographic optical element is arranged on or into at least one glass 11 of the AR / VR glasses. The glass 11 can e.g. be a lens of the glasses.

[0076] Thereby, the distance Z between the projector 1 and the glass 11 can be rather small, for example in the range of the lateral extension L.

[0077] In a schematic spatial view Figure 4 shows a further embodiment of here-described AR / VR glasses. In this embodiment the optical arrangement as, for example, described in connection with Figure 2 is used in which the waveguide 3 comprises at least one reflected surface 3b which is at least in parts curved. For this embodiment the distance Z between the projector 1 and the glasses 11 may be slightly greater than for the embodiment of Figure 3. For illustrating the advantages of a here described optical arrangement , Figure 5 shows an optical arrangement without a waveguide 3 . In this case , the proj ector proj ects the image directly onto a holographic element 4 . For such an arrangement the distance Z between the proj ector and the glass 11 would have to be much greater than that of the embodiments of Figures 3 and 4 and the arrangement would be less compact . Further, this type of system can be bulky and the optical path can be obstructed by the user' s facial features and hair . As every user has a di f ferent shaped face and head, it can be di f ficult to determine a suitable location for the proj ector 1 to sit on the frame 11 of the glasses that can suit every user, where the image can be ef ficiently directed towards the holographic plane / combiner .

[0078] In connection with Figure 6 , a schematic spatial view shows a head-up display with an embodiment of a here described optical arrangement , for example the optical arrangement as described in connection with Figure 1 . The head-up display comprises a windscreen 9 wherein the holographic element 4 is arranged on or into the windscreen .

[0079] In conclusion, it is described to use a waveguide 3 to relay the image from a proj ector 1 exit to the holographic element 4 . The waveguides 3 presented here are shaped both in the forms of a 'wedge ' or a ' curve ' or are combinations of these waveguides .

[0080] The wedge-shaped waveguide as depicted in figure 1 has added benefits for the image quality preservation that are discussed . The curved waveguide 3 mostly benefits the space reduction and adds flexibility in placing the proj ector 1 . This may be beneficial when proj ectors need to be fitted onto variously designed frames .

[0081] This can reduce the form factor considerably by bringing the proj ector 1 further forward onto a frame 11 of a pair of glasses , almost to the same plane as the holographic element 4 .

[0082] The advantages are maintaining good control of the ray bundle and angle distribution of said bundle , enhanced image si ze and enhanced region where the image 2 is being reflected .

[0083] By doing this , a slimmed down architecture is achieved whilst also preserving optimal image quality that in turn is relayed by the holographic element 4 through to the rest of the optical system .

[0084] Alternatively or additionally to the features described in connection with the figures , the exemplary embodiments shown in the figures can comprise further features described in the general part of the description . Moreover, features and embodiments of the figures can be combined with each other, even i f such combination is not explicitly described .

[0085] This patent application claims the priority of German patent applications 102023129416 . 4 and 102023119342 . 2 , the disclosure content of which is hereby incorporated by reference .

[0086] The invention is not restricted to the exemplary embodiments by the description on the basis of said exemplary embodiments . Rather, the invention encompasses any new feature and also any combination of features , which in particular comprises any combination of features in the patent claims and any combination of features in the exemplary embodiments , even i f this feature or this combination itsel f is not explicitly speci fied in the patent claims or exemplary embodiments .

[0087] Reference signs

[0088] 1 proj ector lb blue light emitting laser diode Ir red light emitting laser diode

[0089] 1g green light emitting laser diode

[0090] 2 image

[0091] 3 waveguide

[0092] 3a entrance region 3b reflective surface

[0093] 3c exit region

[0094] 4 holographic element

[0095] 5 first optical element

[0096] 6 second optical element L lateral extension

[0097] 10 frame

[0098] 11 glass

[0099] Z distance

Claims

Claims1. Optical arrangement comprising a projector (1) which is configured to generate an image (2) , a waveguide (3) which is configured to receive the image(2) form the projector (1) , and a holographic element (4) , which is configured to receive the image (2) from the waveguide (3) and to overlay the image (2) , wherein the waveguide (3) comprises an entrance region (3a) for receiving the image (2) from the projector (1) , an exit region (3c) for relaying the image (2) to the holographic element (4) , and at least one reflective surface (3b) for relaying the image (2) from the entrance region (3a) to the exit region (3c) .

2. Optical arrangement according to the previous claim, wherein the waveguide (3) is at least in parts wedge-shaped.

3. Optical arrangement according to at least one of the previous claims, wherein at least one of the at least one reflective surfaces (3b) is at least in parts curved.

4. Optical arrangement according to at least one of the previous claims further comprising a first optical element(5) which is arranged between the projector (1) and the entrance region (3a) of the waveguide (3) .

5. Optical arrangement according to at least one of the previous claims further comprising a second optical element(6) which is arranged between the exit region (3c) of the waveguide (3) and the holographic element (4) .

6. Optical arrangement according to at least one of the two previous claims, wherein the first optical element (5) is in direct contact with the waveguide (3) .

7. Optical arrangement according to at least one of the three previous claims, wherein the second optical element (6) is in direct contact with the waveguide (3) .

8. Optical arrangement according to at least one of the previous claims, wherein the holographic element (4) comprises a holographic combiner and / or a holographic optical element .

9. Optical arrangement according to at least one of the previous claims, wherein the projector (1) comprises at least one laser diode.

10. Optical arrangement according to at least one of the previous claims, wherein the projector (1) comprises a microLED panel.

11. Optical arrangement according to at least one of the previous claims, wherein the image (2) is reflected directly from the holographic element (4) into the eye of a viewer.

12. Head-up display comprising an optical arrangement according to at least one of the previous claims and a windscreen or window pane (9) , wherein the holographic element (4) is arranged on or into the windscreen or window pane .

13. AR / VR-glasses comprising- an optical arrangement according to at least one of the previous claims,- a frame (10) , and- at least one glass (11) , wherein - the projector (1) is attached to the frame (10) , and- the holographic element (4) is arranged on or into the at least one glass.

14. AR / VR-glasses according to the previous claims, wherein the at least one glass (11) is translucent or switchable translucent .

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