Patent Publication Number: US-2018031842-A1

Title: Head-mounted display

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the priority benefit of China application serial no. 201610606220.8, filed on Jul. 28, 2016. The entirety of the above-mentioned patent application is hereby incorporated by reference herein and made a part of this specification. 
     BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The invention relates to a display, and particular relates to a head-mounted display. 
     Description of Related Art 
     Near eye displays (NED) or head-mounted displays (HMD) are currently considered to be wearable displays that are full of potential. The NEDs are divided into the augmented reality (AR)-type and virtual reality (VR)-type based on whether an image of the surroundings is also seen in actual use. Virtual reality emphasizes the sense of reality in a virtual world, namely a wide field of view that exceeds the extreme of human eyes. Augmented reality, on the other hand, focuses on providing the best image quality under the premise of making an apparatus more light-weighted. Currently, the key to the development of optical technologies for AR-type head-mounted displays is how the crucial requirements, namely field of view (FOV), size, weight, and appearance, are taken into consideration at the same time. 
     The information disclosed in this “Description of Related Art” section is only for enhancement understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known to a person of ordinary skilled in the art. Furthermore, the information disclosed in this “Description of Related Art” section does not mean that one or more problems to be solved by one or more embodiments of the invention were acknowledged by a person of ordinary skill in the art. 
     SUMMARY OF THE INVENTION 
     The invention provides a head-mounted display capable of expanding the user&#39;s field of view (FOV) and reducing a size and weight. 
     The invention provides a head-mounted display that is comfortable to wear. 
     Other objects and advantages of the invention can be further illustrated by the technical features broadly embodied and described as follows. 
     In order to achieve one or a part of or all of the objects or other objects, an embodiment of the invention is directed to a head-mounted display including an apparatus body and an image display device. The apparatus body includes a first part and a second part, and the second part is connected to the first part. The image display device is disposed at the apparatus body. The image display device is adapted to project a display image to a projection target. The image display device includes a fiber element and an imaging element. The fiber element is adapted to transmit an illumination beam. The imaging element is adapted to project an image beam to the projection target to display the display image. The fiber element is disposed at the first part of the apparatus body. The imaging element is disposed at one of the first part and the second part of the apparatus body. 
     Based on the above, the embodiments of the invention at least have one of the following advantages or effects. In the image display device according to the embodiments of the invention, the illumination beam required by the image display device to display the display image is transmitted by the fiber element, therefore the appearance of the head-mounted display is fashionable and the head-mounted display is comfortable to wear. Moreover, in the embodiment of the invention, the head-mounted display is also capable of expanding the user&#39;s field of view (FOV) and has a reduced size 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 
         FIG. 1  is a schematic view illustrating a head-mounted display according to an embodiment of the invention. 
         FIG. 2  is a schematic view illustrating a head-mounted display according to another embodiment of the invention. 
         FIG. 3  is an optical schematic view illustrating an image display device according to an embodiment of the invention. 
         FIG. 4  is a schematic view illustrating a light emitting element outputting an illumination beam to a fiber element according to an embodiment of the invention. 
         FIGS. 5 and 6  are schematic cross-sectional views illustrating cross-sections of fiber elements according to different embodiments of the invention. 
         FIGS. 7 and 8  are schematic side views illustrating light collimating elements according to different embodiments of the invention. 
     
    
    
     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 schematic view illustrating a head-mounted display according to an embodiment of the invention. Referring to  FIG. 1 , a head-mounted display  100  of the embodiment includes an apparatus body  110  and an image display device  120 . In the embodiment, the apparatus body  110  includes a first part  112  and a second part  114 , and the second part  114  is connected to the first part  112 . In the embodiment, the apparatus body  110  includes spectacles (glasses), for example. However, the type and configuration of the spectacles (glasses) shall not be construed as limitations on the invention. In the embodiment, the first part  112  includes at least one of a frame, a holder, and a hose pad. In the embodiment, the frame, the holder, and the nose pad may be separately manufactured and then assembled by using a screw or a similar fixer, for example. In an embodiment, the frame, the holder, and the nose pad may also be integrally formed. The invention does not intend to impose a limitation on the type and configuration of the apparatus body. In the embodiment, the second part  114  includes a glass. In the embodiment, the number of the glass may be one or two, for example, and the glass(es) may be assembled on the frame. In other embodiments, the first part  112  and the second part  114  may be integrally formed. For example, the first part  112  and the second part  114  may be integrally formed to be a goggle structure. 
     In the embodiment, the image display device  120  is disposed at the apparatus body  110 . In the embodiment, the image display device  120  is adapted to project a display image to a projection target by virtual image projection. In the embodiment, the projection target is a user&#39;s eye (e.g., a projection target  800  shown in  FIG. 3 ), for example. In other words, in the embodiment, the display image that the user&#39;s eye sees is presented as an enlarged virtual image. 
     In the embodiment, the image display device  120  includes a light emitting element  122 , a fiber element  124 , an image output element  126 , and an imaging element  128 . In the embodiment, the light emitting element  122 , the fiber element  124 , and the image output element  126  are disposed at the first part  112  of the apparatus body  110 . For example, the light emitting element  122  may be disposed at at least one of the frame and the holder of the spectacles (glasses). In the embodiment, the image output element  126  may be disposed at at least one of the frame and the nose pad of the spectacles (glasses). In the embodiment, the fiber element  124  may be disposed at at least one of the frame, the holder, and the nose pad of the spectacles (glasses). The fiber element  124  may extend linearly in a predetermined direction of the frame of the spectacles (glasses) or extend as a curved line or a folding line in a plurality of different directions of the frame of the spectacles (glasses), for example. The invention does not intend to impose a limitation on the arrangement of the fiber element with respect to the first part of the apparatus body. In the embodiment, the imaging element  128  is disposed in one of the first part  112  and the second part  114  of the apparatus body  110 . For example, the imaging element  128  may be integrated to the glass of the spectacles (glasses) or located at an inner side of the glass and tightly attached to the glass. 
     In the embodiment, the light emitting element  122  is adapted to output an illumination beam (e.g., an illumination beam L 1  shown in  FIG. 3 ) to the fiber element  124 . In the embodiment, the fiber element  124  is adapted to transmit the illumination beam from the light emitting element  122  to the image output element  126 . In the embodiment, the image output element  126  is adapted to modulate the illumination beam L 1  to form an image beam L 2 , and output the image beam L 2  to the imaging element  128 . In the embodiment, the imaging element  128  is adapted to project the image beam L 2  to the projection target by virtual image projection for displaying the display image. Namely, in the embodiment, the fiber element  124  is adapted to transmit the illumination beam L 1 , and the imaging element  128  is adapted to project the image beam to the projection target for displaying the display image. In the embodiment, an ambient beam L 3  is adapted to pass through the second part  114  of the apparatus body  110  and be projected to the projection target, for example, such that the head-mounted display  100  is enabled to provide an augmented reality (AR) function. However, the method of transmitting the illumination beam by the fiber element  124  according to the embodiment of the invention may also be used in a head-mounted display for virtual reality (VR) or mixed reality (MR). The invention does not intend to impose a limitation on the applicability of the fiber element. 
     In the embodiment, the fiber element  124  is used in the head-mounted display  100  as a transmitting medium of the illumination beam L 1  between the light emitting element  122  and the image output element  126 . In the embodiment, the light emitting element  122  is disposed at the frame of the spectacles (glasses) near the user&#39;s ear, for example. However, the invention is not limited thereto. In the embodiment, after the illumination beam L 1  emitted by the light emitting element  122  is coupled to the fiber element  124 , the fiber element  124  is arranged to extend to the nose pad of the spectacles (glasses) near the user&#39;s nasal bridge along the frame of the spectacles (glasses) by utilizing a flexible characteristic of the fiber  124 , so as to transmit the illumination beam L 1  to the image output element  126 . Besides, in an embodiment, the frame of the spectacles (glasses) may serve to enclose/cover the fiber element  124 , the fiber element  124  is embedded in the frame of the spectacles (glasses) in the first part  112  of the apparatus body  110 , and the head-mounted display  110  may look like a normal pair of glasses. 
     However, it should be understood that the invention does not intend to impose a limitation on the type and configuration of the apparatus body (e.g., spectacles, glasses).  FIG. 2  is a schematic view illustrating a head-mounted display according to another embodiment of the invention. Referring to  FIGS. 1 and 2 , a head-mounted display  200  of the embodiment is similar to the head-mounted display  100  in the embodiment shown in  FIG. 1 . The difference therebetween mainly lies in the configuration of an apparatus body  210 . For example, in the embodiment, a first part  212  of the apparatus body  210  does not completely enclose/cover the edge of a second part  214 . 
     Referring to  FIG. 2 , in the embodiment, a light emitting element  222  and an image output element  226  are respectively disposed at two different positions away from each other of the frame of the spectacles (glasses). In the embodiment, by utilizing the flexible characteristic of an fiber element  224 , the fiber element  224  may extend along the frame of the spectacles (glasses) in the head-mounted display  200 , such that the illumination beam L 1  emitted by the light emitting element  222  at the frame of the spectacles (glasses) near the ear of a user  900  may be transmitted to the image output element  226  at the nose pad of the spectacles (glasses) near the nasal bridge. In the embodiment, by moving the light emitting element  222  to the frame of the spectacles (glasses) near the ear, a space around the nose pad of the spectacles (glasses) near the nasal bridge may be less crowded. In the embodiment, since the light emitting element  222  and the image output element  226  are disposed at two different positions near the frame and the nose pad of the spectacles (glasses), the weights of the light emitting element  222  and the image output element  226  are respectively carried by the user&#39;s ear and nasal bridge. Thus, in the embodiment, the weight of the head-mounted display  200  is evenly distributed, thereby making the heat-mounted display  200  comfortable to wear. In the embodiment, the imaging element  238  is integrated to the glass of the spectacles (glasses), or the imaging element  238  is located at the inner side of the glass and tightly attached to the glass, and the fiber element  224  transmitting the illumination beam may be enclosed/covered in the frame of the spectacles (glasses) for example, so the appearance of the head-mounted display  200  is fashionable and the awkwardness/exaggeration of the head-mounted display  200  is reduced. 
     Besides, in the embodiment, the descriptions of the embodiment shown in  FIG. 1  have provided sufficient teaching, suggestions, and explanations for embodiment concerning the locations and operations of the respective components in the head-mounted display  200  of the embodiment. Thus, details in these regards will not be reiterated below. 
       FIG. 3  is an optical schematic view illustrating an image display device according to an embodiment of the invention. Referring to  FIG. 3 , an image display device  300  of the embodiment includes a light source module  310 , an image output element  326 , a lens element  330  (second lens element), and an imaging element  328 . In the embodiment, the light source module  310  includes a light emitting element  322 , a lens element  312  (first lens element), a fiber element  324 , and a light collimating element  314 . In the embodiment, the lens element  312  is disposed between the light emitting element  322  and the fiber element  324  on a transmitting path of the illumination beam L 1 . The light collimating element  314  is disposed between the fiber element  324  and the image output element  326  on the transmitting path of the illumination beam L 1 . The lens element  330  is disposed between the image output element  326  and the imaging element  328  on a transmitting path of the image beam L 2 . 
     Specifically, in the embodiment, the light emitting element  322  is adapted to output the illumination beam L 1  to the lens element  312 . In the embodiment, the lens element  312  is adapted to focus the illumination beam L 1  on the fiber element  324 . In the embodiment, the fiber element  324  is adapted to transmit the illumination beam L 1  from the lens element  312  to the light collimating element  314 . Then, in the embodiment, the light collimating element  314  is adapted to collimate the illumination beam and transmit the collimated illumination beam L 1  to the image output element  326 . In the embodiment, the image output element  326  is adapted to output the image beam L 2  to the lens element  330  according to/based on the illumination beam L 1 . In the embodiment, the lens element  330  then is adapted to focus the image beam L 2  on the imaging element  328 . In the embodiment, the imaging element  328  is adapted to project the image beam L 1  to the projection target  800  by virtual image projection for displaying the display image. In the embodiment, the projection target  800  is the user&#39;s eye, for example. 
     In the embodiment, the image display device  300  is disposed at the corresponding apparatus body in a way similar to that shown in the head-mounted display  100  or  200  in  FIG. 1 or 2 . For example, in the embodiment, with respect to the light collimating element  314 , the light emitting element  322  and the lens element  312  are collectively disposed at a first position of the first part of the apparatus body thereof, for example, such as the frame of the spectacles (glasses) near the user&#39;s ear. In the embodiment, with respect to the light emitting element  322  and the lens element  312 , the collimating element  314  and the image output element  326  are collectively disposed at a second position of the first part of the apparatus body, for example, such as the nose pad of the spectacles (glasses) near the user&#39;s nasal bridge. In the embodiment, as shown in the head-mounted display  100  or  200  in  FIG. 1 or 2 , the fiber element  324  may extend as a curve, for example, in a plurality of different directions of the apparatus body, so as to optically couple the lens element  312  and the light collimating element  314 . In an embodiment, the fiber element  324  may also extend as a folding line, for example, in a plurality of different directions of the apparatus body, so as to optically couple the lens element  312  and the light collimating element  314 . Alternatively, in an embodiment, the fiber element  324  may also extend linearly in a predetermined direction of the apparatus body, so as to optically couple the lens element  312  and the light collimating element  314 . 
     In the embodiment, the lens element  312  and the lens element  330  may be a variety of lens elements or a combination thereof, such as a lens, a mirror, a curve mirror, a prism, a mirror-prism, a mirror-lens, or a prism-lens. The invention does not intend to impose a limitation on the types of the lens element. In addition, the locations and operations of the other/respective components of the image display device  300  of the embodiment may be referred to the descriptions of the embodiments shown in  FIGS. 1 and 2 . 
       FIG. 4  is a schematic view illustrating a light emitting element outputting an illumination beam to a fiber element according to an embodiment of the invention. Referring to  FIGS. 3 and 4 , the image display device  300  is taken as an example. For a concise description,  FIG. 4  only illustrates the light emitting element  322  and the fiber element  324 , and the light emitting element  322  is disposed directly at an input end of the fiber element  324 . In the embodiment, the light emitting element  322  may operate synchronously with the image output element  326  under the control of an electronic circuit (not shown) in addition to providing the illumination beam L 1  to the image output element  326 . In the embodiment, the light emitting element  322  may be a light emitting diode (LED), a laser diode (LD), or other photoelectronic elements that are miniaturized and able to emit light, for example. The invention does not intend to impose a limitation on the type of the light emitting element. 
     Referring to  FIG. 3  again, in the embodiment, the illumination beam L 1  emitted by the light emitting element  322  is dispersed/divergent light and focuses on the input end of the fiber element  324  through the lens element  312 , so as to increase the optical coupling efficiency of the illumination beam L 1  entering the fiber element  324 . In the embodiment, the fiber element  324  is adapted to transmit the illumination beam L 1  to the image output element  326  from an output end of the fiber element  324 . In the embodiment, the fiber element  324  is a multimode fiber, for example. In the embodiment, the transmission of the illumination beam L 1  in the multimode fiber is as shown in  FIG. 4 . In the embodiment, a core inside the fiber element  324  is formed with a material having a high refractive index, and a cladding enclosing/covering an outer layer of the core is formed with a material having a low refractive index. Thus, the illumination beam L 1  may have total reflection at an interface between the core and the cladding, and the illumination beam L 1  in the core is thus transmitted through repetitive/continual total reflection. 
       FIGS. 5 and 6  are schematic cross-sectional views illustrating cross-sections of fiber elements according to different embodiments of the invention. Referring to  FIGS. 4 to 6 , in an exemplary embodiment of the invention, a diameter of the core of the multimode fiber is in a range from 50 micrometers to 125 micrometers, for example, and the diameter of the core is a single fiber diameter. In the embodiment, the fiber element  324  includes a plurality of fiber bundles, for example, and a cross-section of the fiber element  324  may be an optical fiber array  324 A or  324 B shown in  FIGS. 5 and 6 . In the embodiment, a structure of such fiber bundle is able to increase a light receiving area when the illumination beam L 1  is coupled to the fiber element  324 . However, the invention does not intend to impose a limitation on the type of the fiber element. 
       FIGS. 7 and 8  are schematic side views illustrating light collimating elements according to different embodiments of the invention. Referring to  FIGS. 4, 7, and 8 , in an exemplary embodiment of the invention, the light collimating element  314  is disposed between the fiber element  324  and the image output element  326  to adjust a distribution of a light shape of the illumination beam L 1  entering the image output element  326 , so that at least the distribution of the light shape of the illumination beam L 1  output by the fiber element  324  meets a requirement of the image output element  326 . In the embodiment, the light collimating element  314  may be in a configuration of a collimating lens shown in  FIG. 7  or a gradient reflective index (GRIN) lens shown in  FIG. 8 , for example. The invention does not intend to limit the type of the light collimating element. For example, the light collimating element  314  may be a Fresnel lens or a liquid crystal lens. 
     In view of the above, the embodiments of the invention at least have one of the following advantages or effects. In the image display device according to the embodiments of the invention, the illumination beam required by the image display device to display the display image is transmitted by the fiber element. In the embodiment of the invention, by utilizing the flexible characteristic of the fiber element, the fiber element may extend on the apparatus body, so as to optically couple the light emitting element and the image output element at different locations. In the embodiment of the invention, such configuration may reduce the crowdedness caused by a collective arrangement of the optical components on the apparatus body, and the weights of the components are also carried/shared by different parts of the user. Thus, in the embodiment of the invention, the weight of the head-mounted display is evenly distributed, thereby making the heat-mounted display comfortable to wear. In addition, in the embodiment of the invention, the imaging element is integrated to the glass of the spectacles (glasses), or the imaging element is located at the inner side of the glass and tightly attached to the glass, and the fiber element transmitting the illumination beam may be enclosed/covered in the frame of the spectacles (glasses), so the appearance of the head-mounted display is fashionable and the awkwardness/exaggeration of the head-mounted display is reduced. 
     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. 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.