Patent Publication Number: US-2018031841-A1

Title: Head-mounted display

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the priority benefit of China application serial no. 201610604870.9, 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 (NEDs) or head-mounted displays (HMDs) 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 can also be 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, can be 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 skill 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 having a reduced size and weight. 
     The invention provides a head-mounted display that has a fashionable appearance and 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 connected to the first part. The image display device is disposed in the apparatus body. The image display device is configured to project an image to a projection target. The image display device includes an image output element, a plurality of lens elements, and an imaging element. The image output element outputs an image beam transmitted to the imaging element through the lens elements. The imaging element projects an image beam to the projection target by virtual image projection, so as to display the image. The image output element and the lens elements are disposed in the first part of the apparatus body. The projection target is located on a reference plane, and a projection of the image output element on the reference plane is above the projection target. 
     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 respective optical elements are at least disposed dispersedly in the first part of the apparatus body. Therefore, the appearance of the head-mounted display is fashionable and the head-mounted display is comfortable to wear. Moreover, the head-mounted display is also capable of expanding the user&#39;s 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 a schematic view illustrating a head-mounted display according to another embodiment of the invention. 
         FIG. 4  is an optical schematic view illustrating an image display device according to an embodiment of the invention. 
         FIG. 5  is an optical schematic view illustrating a light source module according to an embodiment 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 this embodiment includes an apparatus body  110  and an image display device  120 . The apparatus body  110  includes a first part  112  and a second part  114  connected to the first part  112 . In this embodiment, the apparatus body  110  includes spectacles, for example. However, the type and configuration of the spectacles shall not be construed as limitations on the invention. The first part  112  includes at least one of a frame, a holder, and a nose pad. In this 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  110 . The second part  114  includes a lens. The number of the lens may be one or two or more, for example, and the lens 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 this embodiment, the image display device  120  is disposed in the apparatus body  110 . The image display device  120  is adapted to project an image to a projection target by virtual image projection. The projection target may be a user&#39;s eye (e.g., a projection target  800 , the pupil of the user&#39;s eye, shown in  FIG. 4 ), for example. In this embodiment, the image display device  120  includes a light source module  122 , an image output element  126 , an imaging element  128 , a plurality of lens elements  121 _ 1 ,  121 _ 2 , and  121 _ 3 , and a mirror element  123 . In this embodiment, the lens elements  121 _ 1 ,  121 _ 2 , and  121 _ 3  are disposed on a transmitting path of an image beam L 2  generated by the image output element  126 . In addition, the lens elements  121 _ 1 ,  121 _ 2 , and  121 _ 3  are disposed between the image output element  126  and the imaging element  128 . The mirror element  123  is disposed on the transmitting path of the image beam L 2 , and the mirror element  123  is disposed between the lens elements  121 _ 2  and  121 _ 3 . In this embodiment, the light source module  122 , the image output element  126 , the lens elements  121 _ 1 ,  121 _ 2 , and  121 _ 3 , and the mirror element  123  are disposed dispersedly in the first part  112  of the apparatus body  110 . For example, the light source module  122  may be disposed at the holder. The image output element  126  may be disposed at the frame. The lens elements  121 _ 1 ,  121 _ 2 , and  121 _ 3  are disposed dispersedly in the first part  112  of the apparatus body  110 . In this 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 onto the lens of the spectacles or located at an inner side of the lens and tightly attached to the lens. The imaging element  128  may be a transflective film or a splitter, for example, and may be formed on the lens by coating, for example. However, it should be understood that the invention is not limited thereto. 
     In this embodiment, the light source module  122  is configured to output the illumination beam L 1  to the image output element  126 . The image output element  126  modulates the illumination beam L 1 , and outputs the image beam L 2  to the lens elements  121 _ 1 ,  121 _ 2 , and  121 _ 3  and the mirror element  123 . The image beam L 2  is transmitted to the imaging element  128  through the lens elements  121 _ 1 ,  121 _ 2 , and  121 _ 3  and the mirror element  123 . The imaging element  128  then transmits the image beam L 2  to the projection target  800  by virtual image projection, so as to display the image. In this embodiment, the mirror element  123  is configured to change the transmitting path of the image beam L 2 . For example, the mirror element  123  includes a reflective mirror configured to reflect the image beam L 2  from the lens element  121 _ 2  to the lens element  121 _ 3  as well as changing the direction of the image beam L 2 . The number of the mirror element  123  in this embodiment is one, for example. However, based on the designs of different light paths, the number of the mirror element  123  may also be plural. The invention does not intend to impose a limitation on the number of the lens element  123 . 
     In this embodiment, an ambient beam L 3  passes through the second part  114  of the apparatus body  110  and is transmitted to the projection target, for example, such that the head-mounted display  100  is enabled to provide an augmented reality function. However, the method of dispersedly disposing the respective components of the image display device  120  in the embodiments of the invention may also be used in a head-mounted display for virtual reality or mixed reality (MR). The invention does not intend to impose a limitation on the applicability of the image display device  120 . 
     In this embodiment, the image output element  126 , the lens elements  121 _ 1 ,  121 _ 2 , and  121 _ 3 , and the mirror element  123  are arranged along the first part  112  and the second part  114 . For example, in this embodiment, an area where the image output element  126 , the lens elements  121 _ 1 ,  121 _ 2 , and  121 _ 3 , and the mirror element  123  are arranged is near a position of the user&#39;s nose. The position is where the first part  112  and the second part  114  are connected. In this embodiment, the illumination beam L 1  is emitted by the light source module  122 . After passing through the image output element  126 , the illumination beam L 1  becomes a beam carrying image information (i.e., the image beam L 2 ). Then, the image beam L 2  is transmitted into the user&#39;s eye after passing through the lens elements  121 _ 1 ,  121 _ 2 , and  121 _ 3 , the mirror element  123 , and the imaging element  128 , and is focused on the retina by the crystalline lens (as a virtual image, for example) and forms an image. 
     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).  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 this 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  and the number of lens elements. For example, in this embodiment, a first part  212  of the apparatus body  210  does not completely enclose the edge of a second part  214 . In this embodiment, the number of lens elements is 2, and the lens elements are respectively disposed on the transmitting path of the image beam L 2  and between an image output element  226  and a mirror element  223  and between the mirror element  223  and an imaging element  228 . 
     In this embodiment, the projection target is located on a reference plane, and a projection of the image output element  226  on the reference plane is above the projection target. For example, the projection target is the eye of a user  900 , and the reference plane may be a general surface of the face of the user  900 . In this embodiment, the projection of the image output element  226  on the surface of the face of the user  900  is located above the eye and near the eyebrow of the user  900 . In other words, the projection of the image output element  226  on the reference plane is above the projection target. In this embodiment, the lens elements  221 _ 1  and  221 _ 2  are located on an inner side of the eye and are close to the nasal bridge while away from the ear. 
     In this embodiment, with the user  900  as reference, a light source module  222  is disposed on a left side of the user  900 . A traveling direction of a light path is from left to right and then back to left. Namely, the image beam L 2  is transmitted from the user&#39;s  900  eyebrow to his/her nasal bridge, and then transmitted from the nasal bridge to the eye. Moreover, in this embodiment, the imaging element  228  may be integrated onto and combined together with the lens or, as shown in  FIG. 1 , disposed at the inner side of the lens and tightly attached to the lens. In this embodiment, a light source module  310  is disposed at the holder of the spectacles, for example, as shown in  FIGS. 1 to 3 . However, the invention does not intend to impose a limitation on a location of the light source module  310 . In this embodiment, based on practical needs, the light source module  310  may also be disposed at the frame or other appropriate locations. 
     Besides, 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 this embodiment. Thus, details in these regards will not be reiterated below. 
       FIG. 3  is a schematic view illustrating a head-mounted display according to another embodiment of the invention. Referring to  FIGS. 1 and 3 , a head-mounted display  400  of this 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  410 , the number of lens elements, and the number of mirror elements, for example. Besides, for a concise description, the light source module is not shown in  FIG. 3 . 
     Specifically, in this embodiment, there are four lens elements, namely lens elements  421 _ 1 ,  421 _ 2 ,  421 _ 3 , and  421 _ 4 . The lens elements  421 _ 1 ,  421 _ 2 , and  421 _ 3  are disposed on the transmitting path of the image beam L 2  and located between an image output element  426  and a mirror element  423 _ 1 . The lens element  421 _ 4  is disposed on the transmitting path of the image beam L 2  and located between a mirror element  423 _ 2  and an imaging element  428 . The imaging element  428  is disposed in a first part  412  and near the nose pad, for example. In this embodiment, there are two mirror elements, namely the mirror elements  423 _ 1  and  423 _ 2 . The mirror elements  423 _ 1  and  423 _ 2  are disposed between the lens element  421 _ 3  and the lens element  421 _ 4  on the transmitting path of the image beam L 2 . 
     In this embodiment, a distance between the lens element  421 _ 1  and the mirror element  423 _ 1  on an optical axis A is d 1 , a distance between the mirror element  423 _ 1  and the mirror element  423 _ 2  on the optical axis A is d 2 , a distance between the mirror element  423 _ 2  and the lens element  421 _ 4  on the optical axis A is d 3 , and a distance between the imaging element  428  and a projection target  700  is d 4 . In this embodiment, a ratio of a total of the distances d 1 , d 2 , and d 3  to the distance d 4  may be in a range from 2 to 2.5, and such ratio may facilitate an imaging quality of an image display device  420 . For example, in an embodiment, the total of the distances d 1 , d 2 , and d 3  is 38.33 millimeters, for example, the distance d 4  is 16.5 millimeters, for example, and a ratio of the total of the distances d 1 , d 2 , and d 3  to the distance d 4  is about 2.3. The distances and the ratio thereof described above merely serve as an example. It should be understood that the invention is not limited thereto. 
     Besides, the descriptions of the embodiments shown in  FIGS. 1 and 2  have provided sufficient teaching, suggestions, and explanations for embodiment concerning the locations and operations of the respective components in the head-mounted display  400  of this embodiment. Thus, details in these regards will not be reiterated below. 
       FIG. 4  is an optical schematic view illustrating an image display device according to an embodiment of the invention.  FIG. 5  is an optical schematic view illustrating a light source module according to an embodiment of the invention. Referring to  FIGS. 4 and 5 , an image display device  300  includes the light source module  310 , an image output element  326 , a lens module  330  and an imaging element  328 . In this embodiment, the lens module  330  is disposed between the image output element  326  and the imaging element  328  on the transmitting path of the image beam L 2 . The lens module  330  includes one or more lens elements, one or more mirror elements, and a combination thereof, for example. The invention does not intend to impose a limitation on the types of optical elements included in the lens module  330 . 
     In this embodiment, the light source module  310  includes a light emitting element  322 , a lens element  312 , a light transmitting element  324 , and a light collimating element  314 . In this embodiment, the lens element  312  is disposed between the light emitting element  322  and the light transmitting element  324  on a transmitting path of the illumination beam L 1 . The light collimating element  314  is disposed between the light transmitting element  324  and the image output element  326  on the transmitting path of the illumination beam L 1 . 
     Specifically, in this embodiment, the light emitting element  322  provides the illumination beam L 1  that the image output element  326  needs, and outputs the illumination beam L 1  to the lens element  312 . The lens element  312  focuses the illumination beam L 1  on the light transmitting element  324 . The light transmitting element  324  transmits the illumination beam L 1  from the lens element  312  to the light collimating element  314 . Then, the light collimating element  314  collimates the illumination beam and transmits the collimated illumination beam L 1  to the image output element  326 . 
     The image output element  326  outputs the image beam L 2  to the lens module  330  based on the illumination beam L 1 . The lens module  330  then focuses the image beam L 2  on the imaging element  328 . The imaging element  328  projects the image beam L 2  to the projection target  800 , so as to display the image. The projection target  800  is the user&#39;s eye, for example. 
     In this embodiment, the lens element  312  and the lens elements included in the lens module  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  312  and the lens module  330 . 
     In this embodiment, the light transmitting element  324  may be a wave guide, an optical fiber, an integral rod, a light pipe, or the like, for example, and the invention does not intend to impose a limitation on the types of the light transmitting element  324 . In this embodiment, the light collimating element  314  is disposed between the light transmitting element  324  and the image output element  326  to adjust a distribution of a light shape of the illumination beam L 1  when the illumination beam L 1  enters the image output element  326 , so that at least the distribution of the light shape of the illumination beam L 1  output by the light transmitting element  324  meets a requirement of the image output element  326 . The light collimating element  314  may be a Fresnel lens, a liquid crystal lens, or a gradient reflective index (GRIN) lens, for example. However, the invention does not intend to impose a limitation on the types of the light collimating element  134 . Here, an area of the image output element  326  irradiated by the collimated illumination beam L 1  provided by the light collimating element  314  is greater than an effective light emitting area of the image output element  326 . The effective light emitting area of the of the image output element  326  here refers to an area where the image output element  326  adjusts the illumination beam L 1 , such as a liquid crystal adjustable area in a liquid crystal panel. The image output element  326  may be a light modulating device such as a digital micromirror device (DMD), or liquid crystal on silicon (LCoS), for example. 
     In this embodiment, the imaging element  328  is configured to change a traveling direction of the image beam L 2  received from the lens module  330  to transmit the image beam L 2  to the projection target  800  without completely reflecting the ambient beam L 3 . In this way, the user is able see the image of the surrounding in perspective. In this embodiment, the imaging element  328  is an optical element such as a transreflective optical element, a curve half-mirror, a liquid crystal lens, a diffraction component, a holography component, a Fresnel lens, or the like. The invention does not intend to impose a limitation on the type of the imaging element  328 . 
     In this embodiment, the image display device  300  is disposed on the corresponding apparatus body in a way similar to that shown in the head-mounted display  100 ,  200 , or  400  in  FIG. 1, 2 , or  3 . Besides, the descriptions of the embodiments shown in  FIGS. 1, 2, and 3  have provided sufficient teaching, suggestions, and explanations for embodiment concerning the locations and operations of the respective components in the image display device  300  of this embodiment. Thus, details in these regards will not be reiterated below. 
     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 respective optical components are disposed dispersedly on the apparatus body. Such configuration may reduce the crowdedness caused by a collective arrangement of the respective optical components on the apparatus body, and the weights of the components are also shared by different parts of the user. Thus, the weight of the head-mounted display is evenly distributed, thereby making the heat-mounted display comfortable to wear. In addition, since the imaging element is integrated onto the lens of the spectacles or located at the inner side of the lens and tightly attached to the lens, the appearance of the head-mounted display is fashionable, and the awkwardness is significantly 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. 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.