Patent Publication Number: US-2023147618-A1

Title: Wearable display device and projection device

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the priority benefit of U.S. provisional application Ser. No. 63/275,963, filed on Nov. 5, 2021 and China application serial no. 202111548775.9, filed on Dec. 17, 2021. The entirety of the above-mentioned patent application is hereby incorporated by reference herein and made a part of this specification. 
    
    
     BACKGROUND 
     Technical Field 
     The disclosure relates to a display device and a projection device, in particular, the disclosure relates to a wearable display device and a projection device included therein. 
     Description of Related Art 
     Gaining increasing popularity in consumer markets in recent years, wearable display devices with augmented reality (AR) or virtual reality (VR) functions project an image beam onto an optical waveguide element by a projection device for users to experience virtual reality. The volume and weight of the wearable display device need to be reduced as much as possible so that the user may wear it easily. The projection device in the current wearable display device mostly adopts a framework of a light emitting diode (LED) module with digital micromirror devices (DMD). However, the current projection device needs to cooperate with a complex optical path guidance and imaging system, and uses a precise optical engine system to position each element inside the projection device, which leads to an increase in the size and weight of the wearable display device. 
     The information disclosed in this Background section is only for enhancement of understanding of the background of the described technology and therefore it may contain information that does not form the prior art that is already known to a person of ordinary skill in the art. Further, the information disclosed in the Background section does not mean that one or more problems to be resolved by one or more embodiments of the invention was acknowledged by a person of ordinary skill in the art. 
     SUMMARY 
     The disclosure is directed to a wearable display device, in which a projection device complies with design requirements of reduced volume and weight. 
     The disclosure is directed to a projection device, which complies with design requirements of reduced volume and weight. 
     Other objectives and advantages of the disclosure may be further illustrated by the technical features broadly embodied and described as follows. 
     In order to achieve one or a portion of or all of the objectives or other objectives, an embodiment of the disclosure provides a wearable display device including an optical waveguide element and a projection device. The projection device includes an optical engine main body, at least one light emitting unit, an optical combiner and a projection lens. The optical engine main body has at least one positioning structure. The light emitting unit is connected to the optical engine main body and configured to emit an illumination beam. The optical combiner is disposed in the optical engine main body and positioned at the positioning structure, the optical combiner is located on a transmission path of the illumination beam, and the optical combiner is configured to guide the illumination beam to form an image beam. The projection lens is connected to the optical engine main body, and the projection lens is located on a transmission path of the image beam and configured to project the image beam to the optical waveguide element. 
     In order to achieve one or a portion of or all of the objectives or other objectives, an embodiment of the disclosure provides a projection device including an optical engine main body, at least one light emitting unit, an optical combiner and a projection lens. The optical engine main body has at least one positioning structure. The light emitting unit is connected to the optical engine main body and configured to emit an illumination beam. The optical combiner is disposed in the optical engine main body and positioned at the positioning structure, the optical combiner is located on a transmission path of the illumination beam, and the optical combiner is configured to guide the illumination beam to form an image beam. The projection lens is connected to the optical engine main body, and the projection lens is located on a transmission path of the image beam and configured to project the image beam out. 
     In an embodiment of the disclosure, the optical engine main body has at least one first positioning portion, and the at least one first positioning portion includes at least one of a positioning hole and a positioning groove. 
     In an embodiment of the disclosure, the optical engine main body has a positioning surface and a plurality of connecting surfaces, each connecting surface is adjacent to the positioning surface, the at least one light emitting unit and the projection lens are respectively connected to the connecting surfaces, and the at least one first positioning portion is located on the positioning surface. 
     In an embodiment of the disclosure, the light emitting unit has at least one second positioning portion, and the at least one second positioning portion includes at least one of a positioning hole and a positioning edge. 
     In an embodiment of the disclosure, the light emitting unit includes a light emitting assembly and a back plate. The back plate has a front surface and a back surface opposite to each other, the front surface faces the optical engine main body, the light emitting assembly is disposed on the front surface, and the at least one second positioning portion is located on the back surface. 
     In an embodiment of the disclosure, the optical engine main body has a plurality of connecting surfaces, the at least one light emitting unit and the projection lens are respectively connected to the connecting surfaces, where at least one of the connecting surfaces has at least one dispensing groove. 
     In an embodiment of the disclosure, the positioning structure includes at least one of a positioning chute, a positioning hole, and a positioning block. 
     In an embodiment of the disclosure, a volume of the projection device is not more than 1.5 cubic centimeters. 
     Based on the above devices, the embodiments of the disclosure have at least one of the following advantages or effects. In the projection device of the disclosure, the illumination beam emitted by the at least one light emitting unit is guided by the optical combiner to become the image beam, and the image beam may be directly projected to the optical waveguide element by the projection lens to display an image frame. Moreover, the optical combiner is precisely positioned by the positioning structure of the optical engine main body. Compared with a framework in which a projection device in a conventional head-mounted (wearable) display device adopts a light emitting diode module with DMD, the wearable display device and the projection device of the disclosure may omit configuration of the DMD or other types of light valves, and is unnecessary to use a complex optical path guidance and imaging system, and unnecessary to use a precise optical engine system to position each element inside the projection device, which is more in line with the design requirements of reduced volume and weight. 
     Other objectives, features and advantages of the present invention will be further understood from the further technological features disclosed by the embodiments of the present invention wherein there are shown and described preferred embodiments of this invention, simply by way of illustration of modes best suited to carry out the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention. 
         FIG.  1    is a three-dimensional view of a wearable display device worn by a user according to an embodiment of the disclosure. 
         FIG.  2    is a three-dimensional view of partial components of the wearable display device of  FIG.  1   . 
         FIG.  3    is a three-dimensional view of partial components a projection device of  FIG.  2   . 
         FIG.  4    is a cross-sectional view of the projection device of  FIG.  3   . 
         FIG.  5    is an exploded view of the projection device of  FIG.  3   . 
         FIG.  6    is a rear view of the projection device of  FIG.  3   . 
         FIG.  7    is a schematic diagram of the projection device of  FIG.  3   . 
         FIG.  8    is a side view of a light emitting unit of  FIG.  6   . 
         FIG.  9    is a three-dimensional view of an optical engine main body according to an embodiment of the disclosure. 
         FIG.  10    is a three-dimensional view of an optical combiner according to an embodiment of the disclosure. 
         FIG.  11    is a three-dimensional view of an optical engine main body according to another embodiment of the disclosure. 
         FIG.  12    is a three-dimensional view of an optical combiner corresponding to the optical engine main body of  FIG.  11   . 
         FIG.  13    is a three-dimensional view of an optical engine main body of  FIG.  3   . 
         FIG.  14    is a three-dimensional view of partial components of a light emitting unit of  FIG.  3   . 
     
    
    
     DESCRIPTION OF THE EMBODIMENTS 
     In the following detailed description of the preferred embodiments, reference is made to the accompanying drawings which form a part hereof, and in which are shown by way of illustration specific embodiments in which the invention may be practiced. In this regard, directional terminology, such as “top,” “bottom,” “front,” “back,” etc., is used with reference to the orientation of the Figure(s) being described. The components of the present invention can be positioned in a number of different orientations. As such, the directional terminology is used for purposes of illustration and is in no way limiting. On the other hand, the drawings are only schematic and the sizes of components may be exaggerated for clarity. It is to be understood that other embodiments may be utilized and structural changes may be made without departing from the scope of the present invention. Also, it is to be understood that the phraseology and terminology used herein are for the purpose of description and should not be regarded as limiting. The use of “including,” “comprising,” or “having” and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. Unless limited otherwise, the terms “connected,” “coupled,” and “mounted” and variations thereof herein are used broadly and encompass direct and indirect connections, couplings, and mountings. Similarly, the terms “facing,” “faces” and variations thereof herein are used broadly and encompass direct and indirect facing, and “adjacent to” and variations thereof herein are used broadly and encompass directly and indirectly “adjacent to”. Therefore, the description of “A” component facing “B” component herein may contain the situations that “A” component directly faces “B” component or one or more additional components are between “A” component and “B” component. Also, the description of “A” component “adjacent to” “B” component herein may contain the situations that “A” component is directly “adjacent to” “B” component or one or more additional components are between “A” component and “B” component. Accordingly, the drawings and descriptions will be regarded as illustrative in nature and not as restrictive. 
       FIG.  1    is a three-dimensional view of a wearable display device worn by a user according to an embodiment of the disclosure.  FIG.  2    is a three-dimensional view of partial components of the wearable display device of  FIG.  1   . Referring to  FIG.  1    and  FIG.  2   , the wearable display device  10  of the embodiment includes at least one optical waveguide element  12  (two optical waveguide elements  12  are shown in  FIG.  1   ) and at least one projection device  100  (two projection devices  100  are shown in  FIG.  1   ). The wearable display device  10  may be worn on a user  50  as shown in  FIG.  1   , so that the two optical waveguide elements  12  respectively correspond to the two eyes of the user  50 , and each projection device  100  is configured to project an image beam to the corresponding optical waveguide element  12 , and then provide the user  50  with an image experience of augmented reality (AR) or virtual reality (VR) through optical structures included in the optical waveguide element  12  such as a diffractive structure or a light splitting element, etc. 
       FIG.  3    is a three-dimensional view of partial components the projection device of  FIG.  2   .  FIG.  4    is a cross-sectional view of the projection device of  FIG.  3   .  FIG.  5    is an exploded view of the projection device of  FIG.  3   .  FIG.  6    is a rear view of the projection device of  FIG.  3   , where a light emitting unit  120  is shown as transparent to show an optical combiner  130  in an optical engine main body  110 . Referring to  FIG.  3    to  FIG.  6   , the projection device  100  of the embodiment includes the optical engine main body  110 , at least one light emitting unit  120  (a plurality of light emitting units are shown in the figure), the optical combiner  130  and a projection lens  140 . The plurality of light emitting units  120  are, for example, a red micro light emitting diode, a green micro light emitting diode and a blue micro light emitting diode, respectively, and are connected to the optical engine main body  110 . The optical engine main body  110  is, for example, a frame and has a plurality of openings  110   a - 110   d . The optical combiner  130  is disposed in the optical engine maim body  110 , and the light emitting units  120  respectively face the optical combiner  130  through the openings  110   a - 110   c  of the optical engine main body  110 . The projection lens  140  is connected to the optical engine main body  110 , and the opening  110   d  is located between the projection lens  140  and the optical combiner  130 . 
       FIG.  7    is a schematic diagram of the projection device of  FIG.  3   . Referring to  FIG.  7   , the light emitting unit  120  is configured to emit an illumination beam L 1 . The optical combiner  130  is located on a transmission path of the illumination beam L 1 , and the optical combiner  130  is configured to guide the illumination light beam L 1  to form an image beam L 2 . The projection lens  140  is located on a transmission path of the image beam L 2  and configured to project the image beam L 2  to the optical waveguide element  12  (shown in  FIG.  1    and  FIG.  2   ). The illumination beam L 1  includes at least one of red light, green light and blue light. For example, red light emitted by a red micro light emitting diode is reflected by the optical combiner  130  to enter the projection lens  140 , blue light emitted by a blue micro light emitting diode is reflected by the optical combiner  130  to enter the projection lens  140 , and green light emitted by the green micro light emitting diode passes through the optical combiner  130  to enter the projection lens  140 . The image beam L 2  formed by at least one of the red light, green light and blue light (i.e., the aforementioned illumination beam L 1 ) is transmitted to the optical waveguide element  12  through the projection lens  140 , and the user may observe an image formed by the image beam L 2 . 
     As described above, in the projection device  100  of the embodiment, the illumination beam L 1  emitted by the light emitting units  120  is guided by the optical combiner  130  to form the image beam L 2 , and the image beam L 2  may be directly projected to the optical waveguide element  12  by the projection lens  140  to display an image frame. Compared with the framework in which the projection device in the conventional head-mounted (wearable) display device adopts the light emitting diode module with the DMD, the projection device  100  of the embodiment may omit configuration of the DMD or other types of light valves, and is unnecessary to use a complex optical path guidance and imaging system, and unnecessary to use a precise optical engine system to position each element inside the projection device, which is more in line with the design requirements of reduced volume and weight. In the embodiment, a volume of the projection device  100  is, for example, not greater than 1.5 cubic centimeters. 
       FIG.  8    is a side view of the light emitting unit of  FIG.  6   . Referring to  FIG.  6    and  FIG.  8   , the light-emitting unit  120  of the embodiment includes a light emitting assembly  122  and a back plate  124 . The back plate  124  has a front surface  124   a  and a back surface  124   b  opposite to each other, where the front surface  124   a  faces the optical engine main body  110  (shown in  FIG.  6   ), and the light emitting assembly  122  is disposed on the front surface  124   a  and faces the optical combiner  130  in the optical engine main body  110 . In the embodiment, the light emitting unit  120  is fixedly connected to the optical engine main body  110 . To be specific, the light emitting unit  120  is, for example, fixedly connected to the optical engine main body  110  through a structural feature of the front surface  124   a  or through additional structural components. The back surface  124   b  of the back plate  124  may be configured with a heat-dissipating material such as heat sinks, graphite sheets, copper foils, etc., to improve heat dissipation efficiency. In the embodiment, the light emitting assembly  122  may include a micro light emitting diode array, and the micro light emitting diode array at least partially emits light according to an image to be displayed. In the embodiment, the three light emitting assemblies  122  respectively emit red light, green light, and blue light (i.e., the aforementioned illumination beam L 1 ) simultaneously or not simultaneously at specific array positions, and the image beam L 2  is formed after being guided by the optical combiner  130 . 
       FIG.  9    is a three-dimensional view of an optical engine main body according to an embodiment of the disclosure.  FIG.  10    is a three-dimensional view of an optical combiner according to an embodiment of the disclosure. Referring to  FIG.  9    and  FIG.  10   , the optical engine main body  110  of the embodiment has a plurality of positioning structures. In the embodiment, the optical engine main body  110  is embodied as having three positioning blocks  1101  and a positioning chute  1102 , and the optical combiner  130  is positioned at these positioning structures. To be specific, the three positioning blocks  1101  respectively lean against the optical combiner  130  in three axial directions perpendicular to each other. Moreover, as shown in  FIG.  10   , the optical combiner  130  has a boss  1301  corresponding to the positioning chute  1102 , and the boss  1301  is positioned on the positioning chute  1102  in a sliding manner. In the embodiment, the optical combiner  130  is, for example, a combined prism or other optical elements capable of combining a plurality of light path, and a material of the optical combiner  130  is, for example, glass or a transparent plastic material. 
     The positioning structure of the embodiment of the disclosure has various forms, which is described below with reference of following figures.  FIG.  11    is a three-dimensional view of an optical engine main body according to another embodiment of the disclosure.  FIG.  12    is a three-dimensional view of an optical combiner corresponding to the optical engine main body of  FIG.  11   . A difference between the embodiment shown in  FIG.  11    and  FIG.  12    and the previous embodiment ( FIG.  9    and  FIG.  10   ) is that the positioning structure of the optical engine main body  110  shown in  FIG.  11    further includes a plurality of positioning holes  1103  on a plane, and in the embodiment, the optical engine main body  110  is embodied as having two positioning holes  1103 , and the optical combiner  130  shown in  FIG.  12    correspondingly has positioning protrusions  1302 , and in the embodiment, the optical combiner  130  is embodied as having two positioning protrusions  1302 . The positioning protrusions  1302  of the optical combiner  130  may be positioned in the positioning holes  1103  of the optical engine main body  110 . In another embodiment, the positioning structure of the optical engine main body  110  may only include three positioning blocks  1101 , and an outer surface of the optical combiner  130  leans against the three positioning blocks  1101 , so that the optical combiner  130  may be positioned to the optical engine main body  110 . Alternatively, the positioning structure of the optical engine main body  110  may only include two positioning blocks  1101  and one positioning chute  1102 , and the embodiment of the disclosure does not limit the specific numbers of the positioning blocks  1101  and the positioning chute  1102 . 
       FIG.  13    is a three-dimensional view of the optical engine main body of  FIG.  3   .  FIG.  14    is a three-dimensional view of partial components of the light emitting unit of  FIG.  3   . Referring to  FIG.  13    first, the optical engine main body  110  of the embodiment has a positioning surface S 1  and a plurality of connecting surfaces S 2 , and each connecting surface S 2  is adjacent to the positioning surface S 1 . In the embodiment, the connecting surfaces S 2  respectively have openings  110   a - 110   d , and the plurality of light emitting units  120  and the projection lens  140  may be respectively connected to the connecting surfaces S 2  by gluing, buckling, and/or positioning holes, etc. The optical engine main body  110  has a plurality of first positioning portions on the positioning surface S 1 . In the embodiment, the first positioning portions are embodied as having a positioning hole  1104  and a positioning groove  1105 . In addition, as shown in  FIG.  14   , the light emitting unit  120  has a second positioning portion. In the embodiment, the second positioning portion is embodied as having positioning holes  1201  and positioning edges  1202 . The positioning holes  1201  are located on the back surface  124   b  of the back plate  124 , and the positioning edges  1202  are side edges of the back plate  124 . During a process of assembling the projection device  100 , the first positioning portions and the second positioning portions may be positioned by a positioning machine, so that the projection device  100  may be assembled accurately. The second positioning portion of the light emitting unit  120  includes at least two positioning holes  1201 , or the second positioning portion includes at least one positioning hole  1201  and one positioning edge  1202 , so that the positioning machine may position the light emitting unit  120 . The positioning hole  1201  may be, for example, a circular positioning hole or round positioning hole, and the disclosure does not limit a specific appearance of the positioning hole  1201 . In addition, a diameter of the positioning hole  1201  is, for example, greater than 0.8 mm, a depth of the positioning hole  1201  is, for example, greater than 0.3 mm, and a length of the positioning edge  1202  is, for example, greater than 0.3 mm to facilitate the positioning machine positioning the light emitting unit  120 . In other embodiments, the positioning machine may not only position the positioning holes  1201  and/or the positioning edges  1202  of the back plate  124  as described above, but may also position a cover class of the light emitting assembly  122 . The positioning machine may, for example, perform six-axis (up and down, left and right, front and rear) positioning on the light emitting unit  120  of the projection device  100 , and positioning accuracy thereof may, for example, reach 4 μm. In an embodiment, the positioning machine is, for example, an auto alignment (AA) optical engine. 
     In an embodiment, referring to  FIG.  13   , the connecting surfaces S 2  of the optical engine main body  110  further has a dispensing groove G, which is used for pre-dispensing adhesive before the optical engine main body  110  and the light emitting unit  120  or the projection lens  140  are positioned and assembled, so that the corresponding light emitting unit  120  or the projection lens  140  is adhered to the connecting surface S 2  after positioning and assembling. In another embodiment, each connecting surface S 2  may not have the dispensing groove, and pre-dispensing may be directly performed on the connecting surface S 2  so that the corresponding light emitting unit  120  or the projection lens  140  is adhered to the connecting surface S 2  after positioning and assembling. In the embodiment, a dispensing width on the connecting surface S 2  is, for example, greater than 0.5 mm, and a dispensing thickness is, for example, less than 0.5 mm. 
     In summary, the embodiments of the disclosure have at least one of the following advantages or effects. In the projection device of the disclosure, the illumination beam emitted by the light emitting unit is guided by the optical combiner to become the image beam, which may be directly projected to the optical waveguide element by the projection lens to display an image frame. Moreover, the optical combiner is precisely positioned by the positioning structure of the optical engine main body, and the optical engine main body o and the light emitting unit may have positioning portions, which are used by the positioning machine for positioning during the assembling process. Compared with a framework in which a projection device in a conventional head-mounted (wearable) display device adopts a light emitting diode module with DMD, the wearable display device and the projection device of the disclosure may omit configuration of the DMD or other types of light valves, and is unnecessary to use a complex optical path guidance and imaging system, and unnecessary to use a precise optical engine system to position each element inside the projection device, which is more in line with the design requirements of reduced volume and weight. 
     The foregoing description of the preferred embodiments of the invention has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form or to exemplary embodiments disclosed. Accordingly, the foregoing description should be regarded as illustrative rather than restrictive. Obviously, many modifications and variations will be apparent to practitioners skilled in this art. The embodiments are chosen and described in order to best explain the principles of the invention and its best mode practical application, thereby to enable persons skilled in the art to understand the invention for various embodiments and with various modifications as are suited to the particular use or implementation contemplated. It is intended that the scope of the invention be defined by the claims appended hereto and their equivalents in which all terms are meant in their broadest reasonable sense unless otherwise indicated. Therefore, the term “the invention,” “the present invention,” or the like does not necessarily limit the claim scope to a specific embodiment, and the reference to particularly preferred exemplary embodiments of the invention does not imply a limitation on the invention, and no such limitation is to be inferred. The invention is limited only by the spirit and scope of the appended claims. Moreover, these claims may refer to use “first,” “second,” etc. following with noun or element. Such terms should be understood as a nomenclature and should not be construed as giving the limitation on the number of the elements modified by such nomenclature unless specific number has been given. The abstract of the disclosure is provided to comply with the rules requiring an abstract, which will allow a searcher to quickly ascertain the subject matter of the technical disclosure of any patent issued from this disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims. Any advantages and benefits described may not apply to all embodiments of the invention. It should be appreciated that variations may be made in the embodiments described by persons skilled in the art without departing from the scope of the present invention as defined by the following claims. Moreover, no element and component in the present disclosure is intended to be dedicated to the public regardless of whether the element or component is explicitly recited in the following claims.