Patent Publication Number: US-2020278556-A1

Title: Head-mounted display device

Description:
TECHNICAL FIELD 
     The present disclosure relates to a head-mounted display device, and more particularly, to a head-mounted display device which can be easily worn and can measure biometric data of a user. 
     BACKGROUND ART 
     Typically, a head-mounted display (HMD) device is worn on a user&#39;s head and provides the user with virtual reality (VR) images to allow for spatial and temporal experience similar to the reality. 
     Such a head-mounted display device includes a body portion implemented as a goggle that is located around a user&#39;s eyes, and a strap portion implemented as a band that is connected to the body portion and is fixedly worn around the user&#39;s head. As a means for outputting a virtual reality image, a portable terminal device such as a smart phone is mounted at the body portion or a display device such as a monitor connected to a PC or the like is disposed. 
     Previously, a head-mounted display device merely provides a user with visual images output from the image output means installed in a portable terminal device, such that the user can enjoy a visual experience only. As a result, existing head-mounted display devices do not have many applications, and the type of the contents provided from the image output means is very limited. 
     In existing head-mounted display devices, the body portion and the strap portion are formed integrally or the strap portion is implemented as a band that surrounds the head and is made of a rubber material. Accordingly, it is not easy for a user to put on the existing head-mounted display devices. In addition, when a user wants to interrupt the virtual reality experience in order to look around, the user has to take off the device from the head, which is inconvenient. 
     In addition, since the body portion of an existing head-mounted display device is supported by a rubber band around the user&#39;s head, it can not be stably fixed to the user&#39;s face and thus may be deviated from the user&#39;s face during the experience. 
     In addition, in existing head-mounted display devices, a cushioning member is integrally disposed on a surface of the body, which comes in contact with the user&#39;s face. Accordingly, if the cushioning member is deformed or broken, it was not possible to replace it separately. Therefore, if the cushioning member is deformed or broken, the user has to replace the whole head-mounted display device or has to use the head-mounted display device with the cushioning material deformed or broken. 
     SUMMARY OF INVENTION 
     Technical Problem 
     In view of the above, an object of the present disclosure is to provide a head-mounted display device that can be easily put on and can measure biometric data of a user to sense the user&#39;s physical, cognitive and emotional changes. 
     It should be noted that objects of the present invention are not limited to the above-mentioned object; and other objects of the present invention will be apparent to those skilled in the art from the following descriptions. 
     Technical Solutions 
     According to an aspect of the present disclosure, there is provided a head-mounted display device, comprising: a display unit disposed to face a user&#39;s face when the user wears the device and configured to provide the user with virtual reality images via an image output means disposed on one side thereof; a first biometric data acquiring unit disposed at the display unit and configured to capture the user&#39;s face accommodated in the display unit when the user wears the device to acquire first biometric data; and a second biometric data acquiring unit disposed at the display unit and configured to come in contact with the user&#39;s skin when the user wears the device to acquire second biometric data. 
     The display assembly may include: a strap portion that is wearable on the user&#39;s head; and a display body that is rotatably coupled to the strap portion and being positioned in front of the user&#39;s face as the user operates, wherein the display body has a face-accommodating space on one side thereof where the user&#39;s face is to be accommodated, and a display-accommodating space on an opposite side thereof where the image output means is to be accommodated. 
     The strap portion may include: a strap body comprising a band portion having a head-accommodating space formed therein for receiving the user&#39;s head and fitting around the user&#39;s head when the user wears the device, and a band support extended from the band portion and rotatably coupled to a rotation support portion; an inner-diameter adjusting means disposed at the strap body to allow the user to adjust an inner diameter of the strap body; and a buffer portion disposed on an inner surface of the band portion to support the user&#39;s head when the user wears the device. 
     The inner-diameter adjusting means may include: an adjustment portion comprising a support plate coupled to the band portion, and a rotation adjusting member rotatably disposed at a center of the support plate and having a pinion gear on one side thereof; a guide plate disposed on an inner surface of the band portion to face the adjustment portion and has a guide rail formed on one surface thereof in a longitudinal direction; and a moving member that is accommodated in the guide rail and has a rack gear on one side thereof to be engaged with the pinion gear, and a coupling means coupled to the band portion on an opposite side thereof, wherein the moving member moves toward one side or an opposite side when the rotation adjusting member is rotated to adjust the inner diameter of the band portion. 
     The display body may include: a housing having openings in one side and the other side thereof which penetrate the housing; a rotation support portion accommodated in the housing to be rotatably coupled to the wearable portion and restricting an rotation angle of the display body; a clip frame disposed at the opening on the one side of the housing, having the display accommodating space on one side thereof, and linearly movable along the penetration direction of the housing; a face accommodating frame disposed at the opening on the other side of the housing and having the face accommodating space therein; lenses disposed at the face accommodating frame; and a focusing means coupled to the clip frame and configured to move the clip frame according to the user&#39;s operation to separate the display accommodating space from the lenses by a predetermined display. 
     The rotation support member may include: a rotation support body disposed at the display body and capable of accommodating a part of the strap portion; a rotation shaft penetrating the rotation support body and a part of the strap portion accommodated in the rotation support body to rotatably connect the rotation support body with the strap portion; a rotation restricting member coupled to the rotation support body and having projections on a surface thereof that faces the part of the strap portion so that the part of the strap portion is held by the projections when the display body is rotated; and an elastic member connecting the rotation support body with the part of the strap portion and elastically support the rotation support body. 
     The clip frame may include: a shielding portion accommodated in the housing portion to be disposed in front of the face-accommodating frame and comprising a hood surrounding the lenses and an extended portion extended from an end of the hood outwardly to be supported on an inner surface of the housing portion; a display support portion disposed in front of the shielding portion and comprising a first support portion for supporting a vertical load applied to the image output means, and a second support portion extended upwardly from an end of the first support portion for supporting the image output means supported by the first support portion toward the lenses; a cushion pad disposed at the first support portion and the second support portion to be in contact with the image output means; and a linearly-moving member disposed at the shielding portion, having a rack gear formed on a surface thereof in a longitudinal direction to be coupled with the focusing means, and converting a rotation movement of the focusing means into a linear movement to move the shielding portion linearly. 
     The face-accommodating frame may include a face-accommodating body having a coupling means to be coupled with the second biometric data acquiring unit on one surface thereof and having the face-accommodating space where the user&#39;s eyes and nose are to be accommodated; a shielding pad disposed at the face-accommodating body and in tight contact with the user&#39;s nose when the user wears the device to block light from being introduced into the face-accommodating space; and a socket disposed at the face-accommodating body and electrically connected to the second biometric data acquiring unit. 
     The focusing means may include: a pinion gear engaged with the rack gear of the linearly-moving member; a power transmission gear for transmitting rotational power to the pinion gear; and a handle coupled to the power transmission gear, partially exposed out of the housing portion, and transmitting rotational power to the power transmission gear according to the user&#39;s operation. 
     The first biometric data acquiring unit may include: an IR filter disposed in the face-accommodating frame and inclined with respect to a center axis of the lenses at a predetermined angle; an angle adjusting unit disposed between the clip frame and the face-accommodating frame and ratable within a predetermined angle; a capturing unit disposed at the angle adjusting unit and capable of capturing at least a part of the user&#39;s face to acquire the first biometric data; and an IR light source disposed at the angle adjusting unit and disposed around the capturing unit to emit light. 
     The angle adjusting unit may include: a frame disposed in the housing portion and having an accommodating space therein; an operating part comprising a main shaft rotatably coupled to the frame, a main gear coupled to the main shaft and rotatable with the main shaft, and an operating means coupled to the main shaft to rotate with the main gear and the main shaft, wherein a part of the operating means is exposed out of the housing portion so that the user can operate with it; and a rotating body comprising a rotating body accommodated in the frame, wherein the capturing unit and the IR light source are disposed on an inner side thereof, a driven shaft coupled to the rotating body and rotatably coupled to the frame, and a driven gear coupled with one side of the driven shaft to be engaged with the main gear and rotated with the rotating body and the driven shaft as the main gear is rotated. 
     The second biometric data acquiring unit may include: a mask body having a coupling means on one surface thereof that faces the display unit, and being detachably attached to the display unit; a sensing means disposed at the mask body and coming in contact with the user&#39;s skin when the user wear the device to sensing a biometric signal from the user to acquire the second biometric data; and a connector disposed at the mask body and electrically connected to the sensing means, wherein the connector is connected to the socket disposed at the display unit to transmit the second biometric data sensed by the sensing means. 
     Advantageous Effects 
     According to an exemplary embodiment of the present disclosure, the head-mounted display device can not only provide a user with virtual reality image but also acquire biometric data from the user&#39;s face who is watching the virtual reality image to thereby check the user&#39;s cognitive and emotional conditions. Accordingly, it is possible to develop contents including various experience elements. Furthermore, it is possible to improve satisfaction of the user&#39;s experience by providing contents suitable for the user&#39;s current conditions in real-time. 
     Further, since the display body is rotatably coupled to the strap portion and the strap portion is in the form of an annular structure which can be put on by one hand, the user can easily put it on and take it off to look around as desired. As a result, the convenience can be improved. 
     Further, the display body can be stably fixed to the user&#39;s face by the annular strap portion in the form of the structure. Furthermore, even if the user takes a strenuous action during the experience, it is possible to prevent the display body from being deviated from the user&#39;s face. 
     Further, as the mask body supporting the user&#39;s face can be detached from the display body, it is possible to easily replace the mask body, thereby increasing the lifetime of the device while saving the cost. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a perspective view of a front structure of a head-mounted display device according to an exemplary embodiment of the present disclosure; 
         FIG. 2  is a perspective view of a rear structure of the head-mounted display device according to the exemplary embodiment of the present disclosure; 
         FIG. 3  is a front view of the head-mounted display device according to the exemplary embodiment of the present disclosure; 
         FIG. 4  is a cross-sectional view taken along line IV-IV of  FIG. 3 ; 
         FIG. 5  is a side view of the head-mounted display device according to the exemplary embodiment of the present disclosure; 
         FIG. 6  is a cross-sectional view taken along line VI-VI of  FIG. 5 ; 
         FIG. 7  is a rear view of a display body of the head-mounted display device according to the exemplary embodiment of the present disclosure after a face-accommodating frame is removed from it; 
         FIG. 8  is a cross-sectional view taken along line VIII-VIII of  FIG. 3 ; 
         FIG. 9  is a cross-sectional view taken along line IX-IX of  FIG. 3 ; 
         FIG. 10  is an enlarged view of portion A of  FIG. 9 ; 
         FIG. 11  is a plan view of the display body of the head-mounted display device according to the exemplary embodiment of the present disclosure after a housing portion is removed from it; 
         FIG. 12  is a rear view of the display body of the head-mounted display device according to the exemplary embodiment of the present disclosure; 
         FIG. 13  is a front view of a first biometric data acquiring unit of the head-mounted display device according to the exemplary embodiment of the present disclosure; 
         FIG. 14  is a perspective view of a rear structure of the first biometric data acquiring unit of the head-mounted display device according to the exemplary embodiment of the present disclosure; 
         FIG. 15  is a front view of a frame of a second biometric data acquiring unit of the head-mounted display device according to the exemplary embodiment of the present disclosure; 
         FIG. 16  is a longitudinal sectional view of the second biometric data acquiring unit of the head-mounted display device according to the exemplary embodiment of the present disclosure; 
         FIG. 17  is a view showing a way how the second biometric data acquiring unit of the head-mounted display device according to the exemplary embodiment of the present disclosure comes in contact with the user; 
         FIG. 18  is a front view of a buffer portion disposed at frame of the second first biometric data acquiring unit of the head-mounted display device according to the exemplary embodiment of the present disclosure; 
         FIG. 19  is a cross-sectional view of a modification of a sensing means at the second biometric data acquiring unit of the head-mounted display device according to the exemplary embodiment of the present disclosure; 
         FIG. 20  is a front view of the second biometric data acquiring unit of the head-mounted display device according to the exemplary embodiment of the present disclosure. 
         FIG. 21  is a view showing a modification of a sensing means disposed at the second biometric data acquiring unit of the head-mounted display device according to the exemplary embodiment of the present disclosure; 
         FIG. 22  is a cross-sectional view of a connector at the second biometric data acquiring unit of the head-mounted display device according to the exemplary embodiment of the present disclosure; 
         FIG. 23  is a rear view of the second biometric data acquiring unit of the head-mounted display device according to the exemplary embodiment of the present disclosure. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Hereinafter, exemplary embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. 
     While the exemplary embodiments of the present disclosure are susceptible to various modifications and alternative forms, specific exemplary embodiments thereof are shown by way of example in the drawings and will herein be described in detail. 
     It should be understood, however, that the drawings and detailed description thereto are not intended to limit the exemplary embodiments of the present disclosure to the particular form disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the present disclosure as defined by the appended claims. 
     The terms first, second, third and the like in the description and in the claims are used for distinguishing between similar elements and not necessarily for describing a sequential or chronological order. The terms are used only for distinguishing one component from another component. 
     In the specification, it is to be noted that the terms “comprising” or “including” and the like are not to be construed as necessarily including all of the several features, numbers, steps, operations, components or combinations thereof described in the specification. Rather, some of the several features, numbers, steps, operations, components or combinations thereof may not be included or additional several features, numbers, steps, operations, components or combinations thereof are construed as being further included. It is to be understood that when one element is referred to as being “connected to” or “coupled to” another element, it may be connected directly to or coupled directly to another element or be connected to or coupled to another element, having the other element intervening therebetween. In contrast, when an element is referred to as being “directly connected” or “directly coupled” to another element, there are no intervening elements present. 
     As used herein, an element referred by the term “module” or “unit” performs at least one function or operation. The module or unit performing the function or operation may be implemented as hardware, software, or a combination of hardware and software. In addition, a plurality of “modules” or a plurality of “units” other than those that are to be performed in a particular hardware or at least one processor may be integrated into at least one module. As used herein, the singular forms are intended to include plural forms as well, unless the context clearly indicates otherwise. 
     In other instances, well known methods, procedures, components, and circuits have not been described in detail as not to unnecessarily obscure aspects of the exemplary embodiments presented 
     Referring to  FIGS. 1 and 2 , a head-mounted display device  1  according to an exemplary embodiment of the present disclosure (hereinafter referred to as a head-mounted display device  1 ) is worn on a user&#39;s head, provides the user with virtual reality (VR) images to allow for spatial and temporal experiences similar to the reality, and also measures the user&#39;s biometric data to sense physical, cognitive and emotional changes during the experience. The head-mounted display device  1  includes a display assembly  10 . 
     The display assembly  10  can be worn on a user&#39;s head, and one side of the display assembly  10  is disposed to face the user&#39;s face so that the user can see a virtual reality image when the user wears the device. On the side of the display assembly  10 , an image output means (not shown) for providing the user with a virtual reality image is disposed. For example, the image output means may include a portable terminal device such as a smart phone and a tablet PC, and a portable monitor connected to a PC to output an image provided from the PC. 
     Referring to  FIGS. 3 to 12 , the display assembly  10  will be described in more detail. 
     The display assembly  10  may include a strap portion  11 . 
     Referring to  FIG. 3 , the strap portion  11  may have in a structure that can be worn on the user&#39;s head. More specifically, the strap portion  11  may be formed in an annular band structure so as to surround a user&#39;s head when the user wears the device. 
     Referring to  FIGS. 4 and 5 , the strap portion  11  may include a strap body  111  and an inner-diameter adjusting means  112 . 
     The strap body  111  may be formed in a circular or elliptical ring shape having a cut-away portion, such that it may include a head-accommodating space  1111   a  on its inner side in which a user&#39;s head is accommodated, and a band portion  1111  fitting around the user&#39;s head when the user wears the device. In addition, the strap body  111  may include a band support  1112  that is extended in a direction from one end of the band portion  1111  and rotatably coupled to a display body  12  to be described later. On one side of the band support  1112 , a plurality of rotation supporting pieces  11121  may be formed, which protrudes outwardly from the inner side of the band support  1112  and accommodated in the display body  12  and is coupled with a rotation support portion  122  of the display body  12  to be described below. For example, the strap portion  11  may be made of a plastic material having a certain elasticity. A reinforcing means may be formed continuously along the inner surface of the strap portion  11  to supplement the strength of the strap portion  11 . 
     The inner-diameter adjusting means  112  may be disposed at the cut-away portion of the band portion  1111  to connect both ends of the band portion  1111  separated from each other at the cut-away portion. The user may move the ends of the band portion  1111  to adjust the inner diameter of the strap body  111 . 
     The inner-diameter adjusting means  112  will be described in more detail with reference to  FIGS. 4 and 6 . 
     The inner-diameter adjusting means  112  may include an adjustment portion  1121 . 
     The adjustment portion  1121  may be disposed between the separated two ends of the band portion  1111 , and may include a support plate  11211  that is coupled with the band portion  1111  to connect the separated two ends of the band portion  1111  to each other. For example, the support plate  11211  may be formed in an arc shape conforming to the inner surface of the band portion  1111  so as to be connected to the band portion  1111 , and may have a fastening means such as a hook on one side thereof so as to be coupled with the band portion  1111 . The adjustment portion  1121  may include a rotation adjusting member  11212  which is rotatably disposed at the central portion of the support plate  11211 . The rotation adjusting member  11212  may be rotatably disposed at the center portion of the support plate  11211 . The rotation adjusting member  11212  may include a grasping means disposed on the outer side of the band portion  1111  and a pinion gear  11212   a  disposed on the inner side of the band portion  1111 . 
     Further, the inner-diameter adjusting means  112  may include a guide plate  1122 . 
     The guide plate  1122  may be disposed on the inner surface of the band portion  1111  to be opposed to the support plate  11211  of the adjustment portion  1121  and may be formed in an arc shape conforming to the inner surface of the band portion  1111  so as to support the inner surface of the band portion  1111 . A guide rail  11221  may be formed along the longitudinal direction of the guide plate  1122  so that a moving member  1123  to be described later may be disposed on a surface of the guide plate  1122  in contact with the inner surface of the band portion  1111 . For example, more than one guide rails  11221  may be formed on the guide plate  1122  in the vertical direction of  FIG. 6 . In addition, the guide plate  1122  may have fastening means such as a hook on one side thereof to be coupled to the band portion  1111 . 
     In addition, the inner-diameter adjusting means  112  may include the moving member  1123 . 
     The moving member  1123  may be formed in an arc shape conforming to the inner surface of the guide plate  1122  so that it is accommodated in the guide rail  11221  and moves along the inner surface of the guide plate  1122 . A rack gear  11231  engaged with the pinion gear  11212   a  of the rotation adjusting member  11212  may be formed on one side of the moving member  1123 , and a coupling means coupled to the band portion  1111  may be formed on the other side of the moving member  1123 . Therefore, when the rotation adjusting member  11212  is rotated, the moving member  1123  may move toward one side or the other side along the inner surface of the guide plate  1122  and may move the separated two ends of the band portion  1111  so that they become close to or away from the rotation adjusting member  11212 , to adjust the inner diameter of the band portion  1111 . 
     The strap portion  11  may further include a buffer portion  113 . 
     Referring to  FIG. 4 , the buffer portion  113  may be disposed on the inner surface of the band portion  1111  and may support a user&#39;s head when the user wears the device. More specifically, the buffer portion  113  may include a mounting plate capable of being detachably attached to the inner surface of the band portion  1111 , a cushioning material attached to one surface of the mounting plate, and an outer cover disposed on the outer surface of the cushioning material and in contact with the user&#39;s skin when the user wears the device. For example, the mounting plate may be formed in a shape conforming to the inner surface of the band portion  1111 , and fastening means may be disposed on one surface of the mounting plate to fasten to the band portion  1111 . The cushioning material may be formed of a material such as sponge and latex having a predetermined thickness. The outer cover may be formed of a material such as fabric, leather and nylon. More than one buffer portions  113  may be disposed on the inner surface of the band portion  1111 . For example, the buffer portions  113  may be disposed at opposite positions, respectively, on the inner surface of the band portion  1111  so that they are located at front and rear of the user&#39;s head when the user wears the device. 
     The display assembly  10  may include a display body  12 . 
     Referring to  FIG. 4 , the display body  12  is rotatably coupled to the strap portion  11 , and may be positioned in front of a user&#39;s face as the user operates. A face-accommodating space  12   b  in which a part of a user&#39;s face is accommodated may be formed on one side of the display body  12 , and a display-accommodating space  12   a  in which the image output means is accommodated may be formed on the other side of the display body  12 . 
     The display body  12  will be described in more detail. 
     The display body  12  may include a housing portion  121 . 
     Referring to  FIGS. 7 and 8 , the housing portion  121  is formed in a tubular structure having openings at one end and the other end, respectively, which are connected to each other through the housing portion  121  in a direction. Accordingly, the housing portion  121  may accommodate therein the rotation support portion  122 , a clip frame  123 , a face-accommodating frame  124 , a focusing means  126  and a first biometric data acquiring unit  20 , which will be described in detail below. A cable protector  1211  may be formed on a side surface of the housing portion  121 , which protrudes outwardly so as to surround and support a cable (not shown) connected to the display body  12 . A through hole (not shown) may be formed in the other side surface of the housing portion  121  facing the cable protector  1211  so that a part of the focusing means  126  may be disposed therein. A movement restricting support  1212  may be formed on the inner surface of the housing portion  121 , which guides the movement of the clip frame  123  and restricts the movement of the clip frame  123  to maintain the minimum spacing between the display-accommodating space  12   a  and lenses  125 . 
     The display body  12  may further include the rotation support portion  122 . 
     Referring to  FIG. 9 , the rotation support portion  122  may be coupled to the housing portion  121  and is accommodated in the upper side in the housing portion  121  and may be rotatably coupled with the rotation support piece  11121  of the strap portion  11 . The rotation support portion  122  may limit the rotation angle of the display body  12 . 
     The rotation support portion  122  will be described in more detail with reference to  FIGS. 10 and 11 . 
     The rotation support portion  122  may include a rotation support body  1221 , a rotation shaft  1222 , a rotation restricting member  1223 , and an elastic member  1224 . 
     The rotation support body  1221  may be disposed in the housing portion  121  of the display body  12  and has an accommodating space therein so that a part of the strap portion  11 , that is, the rotation support piece  11121  can be accommodated in it. For example, a support structure may be formed at the center portion of the rotation support body  1221 , in which the rotation shaft  1222  is disposed. An accommodating space for accommodating the rotation support piece  11121  may be formed on either side of the center portion. 
     The rotation shaft  1222  is formed in the shape of a pin having a circular cross-section. As shown in  FIG. 4 , the rotation shaft  1222  may penetrate the rotation support body  1221  and a part of the strap portion  11  accommodated in the rotation support body  1221  (the rotation support piece  11121 ) to rotatably connect the rotation support body  1221  with the strap portion  11 . 
     Referring back to  FIGS. 10 and 11 , the rotation restricting member  1223  is coupled with the lower surface of the rotation support body  1221 . A plurality of projections  12231  may be formed on the surface of the rotation restricting member  1223  that faces a part of the strap portion  11  (the end of the rotation support piece  11121 ) so that a part of the strap portion  11  is stopped by the projections when the display body  12  is rotated. Accordingly, the user may rotate the display body  12  or the strap portion  11  upwardly or downwardly so that the end of the rotation support piece  11121  is stopped by one of the projections  12231 , thereby adjusting the rotation angle of the display body  12  or the strap portion  11 . For example, when the user wears the head-mounted display device  1 , the user first rotates the strap portion  11  upwardly so that the rotation support piece  11121  is stopped and supported by the projections  12231 , such that the strap portion  11  is fixed to the display body  12 , tilted at a certain angle. Subsequently, while the strap portion  11  is tilted fixedly, the user brings the surface of the display body  12  into tight contact with her/his face, and then rotates the strap portion  11  downwardly to put the strap portion  11  on her/his head. 
     On the other hand, if the user puts on the strap portion  11  first, the user rotates the display body  12  upwardly so that the projections  12231  are stopped and supported by the rotation support piece  11121 , such that the display body  12  is fixed to the strap portion  11 , tilted at a certain angle. Subsequently, while the display body  12  is tilted fixedly, the user puts the strap portion  11  on her/his head, and then rotates the display body  12  downwardly to bring the surface of the display body  12  in tight contact with the user&#39;s face. That is to say, the rotation restricting member  1223  fixes either the display body  12  or the strap portion  11  depending on the order that the user wears the device so that they are tilted at a certain angle, thereby preventing the display body  12  or the strap portion  11  comes down to the user&#39;s face or head when the user puts it on. As a result, the user can easily and stably put on the device. 
     The elastic member  1224  may connect the rotation support body  1221  with a part of the strap portion  11  and may elastically support the rotation support body  1221 . For example, the elastic member  1224  may be implemented as a tension coil spring having hooks at both ends thereof. More than one elastic members  1224  may be disposed on the inner side of the rotation support body  1221 . 
     The display body  12  may further include the clip frame  123 . 
     Referring to  FIG. 9 , the clip frame  123  is accommodated in the housing portion  121  to be disposed at one opening of the housing portion  121 , and is connected to the focusing means  126 , which will be described later. The clip frame  123  may be moved linearly toward one side or the other side along the direction in which the housing portion  121  is penetrated as being driven by the focusing means  126 . The display-accommodating space  12   a  in which the image output means can be disposed may be formed on one side of the clip frame  123 . 
     The clip frame  123  will be described in more detail. 
     The clip frame  123  may include a shielding portion  1231 , a display support portion  1232 , cushion pads  1233 , and a linearly-moving member  1234 . 
     The shielding portion  1231  is disposed around the front of the lenses  125  to be described later, and can block light or foreign substances from being introduced into the lenses  125 . More specifically, the shielding portion  1231  may be accommodated in the housing portion  121  to be disposed in front of the face-accommodating frame  124 , and may include a hood  12311  surrounding the front circumference of the lenses  125 , and an extended portion  12312  extended outwardly from the end of the hood  12311  and supported on the inner surface of the housing portion  121 . 
     The display support portion  1232  is disposed in front of the shielding portion  1231  to form the display-accommodating space  12   a  between the front surface of the shielding portion  1231  and the surface facing the front surface of the shielding portion  1231 , and may support the image output means placed in the display-accommodating space  12   a . More specifically, the display support portion  1232  may be disposed in front of the shielding portion  1231  and may include a first support portion  12321  for supporting a vertical load applied to the image output means, and a second support portion  12322  extended upwardly from the end of the first support portion  12321  for supporting the image output means supported by the first support portion  12321  toward the lenses  125 . For example, the second support portion  12322  may be extended from the end of the first support portion  12321  such that it is inclined toward the lenses  125  at a predetermined angle. Although not shown in the drawings, an elastic plate (not shown) may be further disposed on the inner side of the display support portion  1232 , which can bend the second support portion  12322  outwardly by a certain angle using an elastic force. By doing so, the width of the display-accommodating space  12   a  can be adjusted, so that image output means having different thicknesses can be mounted. 
     The cushion pads  1233  may be disposed on the front surface of the shielding portion  1231 , on one surface of the first support portion  12321  exposed to the display-accommodating space  12   a  and on one surface of the second support portion  12322  facing the front surface of the shielding portion  1231 , such that it may come in contact with the image output means (not shown). 
     For example, the cushion pads  1233  may absorb shock transmitted to the image output means and may be formed of a rubber or silicone material having a certain frictional force with respect to the object to support so as to prevent deviation of the image output means. 
     Referring to  FIG. 8 , the linearly-moving member  1234  may be disposed behind the shielding portion  1231  and may be extended in one direction by a predetermined length. A rack gear  12341  may be formed on one surface of the linearly-moving member  1234  along the longitudinal direction to be engaged with a pinion gear  1261  disposed at the focusing means  126 . Accordingly, as the pinion gear  1261  of the focusing means  126  is rotated, the linearly-moving member  1234  may convert the rotational motion of the focusing means  126  into a linear motion to linearly move the shielding portion  1231 . 
     The display body  12  may further include the face-accommodating frame  124 . 
     Referring to  FIGS. 4 and 12 , the face-accommodating frame  124  may be accommodated in the housing portion  121  to be disposed at the opening of the housing on the other side. The face-accommodating space  12   b  in which a part of the user&#39;s face is to be accommodated may be formed on the inner side of the face-accommodating frame  124 . 
     The face-accommodating frame  124  will be described in more detail. 
     The face-accommodating frame  124  may include a face-accommodating body  1241 , a shielding pad  1242 , and a socket  1243 . 
     The face-accommodating body  1241  may be disposed on the inner side of the housing portion  121  and may have a coupling means (not shown) on one surface thereof, which can be coupled with a second biometric data acquiring unit  30 . For example, the coupling means may be implemented with velcro. It is, however, to be understood that the present disclosure is not limited thereto. The coupling means may be implemented in a variety of ways as long as it can perform the same functionality. The face-accommodating space  12   b  in which a part of the user&#39;s face is to be accommodated may be formed on the inner side of the face-accommodating frame  1241 . Specifically, one side of the face-accommodating body  1241  in which the second biometric data acquiring unit  30  is to be disposed has a structure recessed to a predetermined depth toward the front, so that the face-accommodating space  12   b  in which the user&#39;s eyes and nose can be accommodated may be formed therein. When the user wears the head-mounted display device  1 , the face-accommodating space  12   b  is shielded from light and remains dark, like a darkroom. 
     The shielding pad  1242  may be disposed at the face-accommodating body  1241  and disposed in the face-accommodating space  12   b  in which the user&#39;s nose is to be located. Therefore, when a user wears the head-mounted display device  1 , the shielding pad  1242  is brought into tight contact with the user&#39;s nose located in the face-accommodating space  12   b , such that the light introduced into the face-accommodating space  12   b  from below the display body  12 . For example, the shielding pad  1242  may have a plurality of cut-out grooves formed therein and may be formed in a plate-like shape having a predetermined thickness. The shielding pad  1242  may be formed of rubber, silicone, a stretchable and flexible material, etc. so that the shielding pad  1242  having elasticity or stretchability can be in tight in contact with the user&#39;s nose when the shielding pad  1242  is pressed against the user&#39;s nose. In addition, a means for coupling to the face-accommodating body  1241  may be disposed on one surface of the shielding pad  1242 . 
     The socket  1243  may be disposed at the face-accommodating body  1241  and electrically connected to a connector  33  disposed at the second biometric data acquiring unit  30 . For example, the socket  1243  may include a connection pin connectable to a pin  332  of the connector  33 , and a magnetic substance detachably attached to a magnet  333  of the connector  33 . 
     The display body  12  may further include the lenses  125 . 
     Referring to  FIGS. 9 and 12 , more than one lenses  125  may be disposed inside the face-accommodating frame  124  and may be arranged symmetrically with respect to the width direction of the face-accommodating frame  124 . For example, annular fixing holes may be formed around the lenses  125  in the face-accommodating body  1241  to support the lenses  125 . The lenses  125  may have a spherical structure having two convex surfaces. 
     The display body  12  may further include the focusing means  126 . 
     Referring to  FIGS. 7 and 8 , the focusing means  126  may be accommodated in the housing portion  121  and coupled to the clip frame  123 . The focusing means  126  may move the clip frame  123  according to the user&#39;s operation so that the display-accommodating space  12   a  can be spaced from the lenses  125  by a predetermined distance. 
     More specifically, the focusing means  126  may include the pinion gear  1261  engaged with the rack gear  12341  of the linearly-moving member  1234 , and a power transmission gear  1262  for transmitting rotational power to the pinion gear  1261 . The focusing means  126  may be rotatably disposed in the housing portion  121  so that one side thereof is coupled to the power transmission gear  1262  and the other side thereof is exposed out of the housing portion  121  to form a handle  1263  that the user can grasp. Accordingly, the user may turn the handle  1263  clockwise or counterclockwise to transmit the rotational power to the power transmission gear  1262 . For example, more than one power transmission gears  1262  may be disposed. In addition, a gear protector for accommodating the power transmission gears  1262  therein may be disposed in the clip frame. 
     The head-mounted display device  1  further includes the first biometric data acquiring unit  20 . 
     Referring to  FIGS. 2 and 9 , the first biometric data acquiring unit  20  is disposed on the inner, lower side of the display assembly  10 , and captures the user&#39;s face accommodated in the display assembly  10  when the user wears the device to acquire the first biometric data from at least a part of the user&#39;s face. More specifically, the first biometric data acquiring unit  20  may acquire, from the captured image of the user&#39;s face accommodated in the display assembly  10 , identification information based on the eyes&#39; movement and the iris region around the pupil, changes in facial expressions based on muscular movements around the eyes, heart rate information based on changes in blood flow in the blood vessels around the eyes. 
     Referring to  FIGS. 7 and 9 , the first biometric data acquiring unit  20  may include an infrared ray (IR) filter  21  and an angle adjusting unit  22 . 
     The IR filter  21  may be disposed at the face-accommodating frame  124  and may be inclined at a predetermined angle with respect to the central axis direction of the lenses  125 . For example, the IR filter  21  may have a plate-like structure with a predetermined thickness and may be made of a transparent material that transmits infrared ray. 
     The angle adjusting unit  22  may be disposed rotatably within a predetermined angle between the clip frame  123  and the face-accommodating frame  124 . 
     The angle adjusting unit  22  will be described in more detail. 
     Referring to  FIGS. 13 and 14 , the angle adjusting unit  22  may include a frame  221 , an operating part  222 , and a rotating part  223 . 
     The frame  221  may be disposed at the housing portion  121 , and may have a space in which the operating part  222  and the rotating part  223  are accommodated. In addition, on either side of the frame  221 , a through hole may be formed in which a main shaft  2221  of the operating part  222 , and a driven shaft  2232  of the rotating part  223  are rotatably disposed, which will be described in detail below. 
     The operating part  222  is disposed at the frame  221  and is coupled to the rotating part  223  and can transmit rotational power to the rotating part  223  according to a user&#39;s operation. More specifically, the operating part  222  may include a main shaft  2221  rotatably coupled to the frame  221 , a main gear  2222  coupled to the main shaft  2221  and rotatable with the main shaft  2221 . In addition, the operating part  222  may include an operating means  2223  that is coupled to the main shaft  2221  to rotate with the main gear  2222  and the main shaft  2222 . A part of the operating means  2223  is exposed out of the housing portion  121  so that the user can operate with it. 
     The rotating part  223  may be disposed at the frame  221  to be coupled with the operation part  222  and may receive the rotational power from the operation part  222  to be rotated clockwise or counterclockwise. More specifically, the rotation part  223  may include a rotating body  2231  accommodated in the frame  221 . A capturing unit  23  and an IR light source  24 , which will be described later, may be disposed on the inner side of the rotating body  223 . The rotating body  223  may include the driven shaft  2232  coupled to the rotating body  2231  and rotatably coupled to the frame  221 , and a driven gear  2232  coupled with one side of the driven shaft  2232  to be engaged with the main gear  2222  and rotated with the rotating body  2231  and the driven shaft  2232  as the main gear  2222  is rotated. 
     The first biometric data acquiring unit  20  may further include the capturing unit  23  and the IR light source  24 . 
     Referring again to  FIGS. 7 and 9 , the capturing unit  23  is disposed at the angle adjusting unit  22  so that the angle can be adjusted according to the user&#39;s operation. In this manner, the capturing unit  23  may capture a particular portion or the whole of the user&#39;s face accommodated in the face-accommodating space  12   b  to acquire the first biometric data from at least a part of the user&#39;s face. For example, the capturing unit  23  may include a camera body including at least one lens therein, and an image sensor connected to the camera body. The capturing unit  23  located at the lower side of the display body  12  may be inclined at a predetermined angle with respect to the central axis of the lenses  125  so that the user&#39;s face accommodated in the face-accommodating space  12   b  can be captured. An infrared camera may be employed as the capturing unit  23 . 
     The IR light source  24  is disposed around the capturing unit  23  and may emit infrared light that can pass through the IR filter  21  when the capturing unit  23  is driven. Further, the IR light source  24  may be disposed at the angle adjusting unit  22 , so that the angle of the IR light source  24  may be adjusted according to a user&#39;s operation. Accordingly, the user may adjust the angle of the IR light source  24  to irradiate a particular portion or the whole of the user&#39;s face accommodated in the face-accommodating space  12   b  with light. For example, an infrared LED or an infrared lamp may be employed as the IR light source  24 . 
     The head-mounted display device  1  further includes the second biometric data acquiring unit  30 . 
     Referring to  FIG. 2 , the second biometric data acquiring unit  30  is detachably attached to the display assembly  10  and comes in contact with the user&#39;s skin when the user wears the device to acquire second biometric data, which is a biometric signal of the user. 
     The second biometric data acquiring unit  30  will be described in more detail with reference to  FIGS. 15 to 23 . 
     Referring to  FIGS. 2 and 15 , the second biometric data acquiring unit  30  may include a mask body  31 . 
     The mask body  31  may be formed in a curved structure along the width direction (y-axis direction) and the height direction (z-axis direction). The mask body  31  may have a viewing hole  311   a  formed therein which connects the lenses  125  disposed at the display assembly  10  with the user&#39;s eyes. 
     The mask body  31  may be detachably attached to the display assembly  10 . 
     Referring to  FIG. 15 , coupling means  314  for fixing the mask body  31  to the display assembly  10  may be disposed on the surface of the mask body  31  that faces the display assembly  10 . More specifically, a plurality of coupling means  314  may be disposed on the surface of the mask body  31  that is opposed to the surface of the mask body  31  where a sensing means  32  to be described later is disposed, and may be disposed at several regions along the edge of the mask body  31 . For example, the coupling members  314  may be implemented with velcro. 
     It is, however, to be understood that the present disclosure is not limited thereto. The coupling means may be implemented in a variety of ways as long as they can perform the same functionality. 
     The mask body  31  may further include a frame  311 . 
     Referring to  FIG. 16 , the frame  311  may face and surround the user&#39;s forehead and the eyes when the user wears the device. In addition, a viewing hole  311   a  may be formed on the inner side of the frame  311 , in which the user&#39;s eyes and nose may be located. 
     The frame  311  will be described in more detail. 
     The frame  311  may include a first support portion  3111  and a second support portion  3112 . 
     The first support portion  3111  may face the user&#39;s forehead when the user wears the device. A mounting groove  3111   a  may be formed at the center portion on the inner side of the first support portion  3111 , which is depressed to a certain depth in a direction (x-axis direction in  FIG. 1 ) so that the connector  33  to be described later may be disposed. In the mounting groove  3111   a , a through hole  3111   b  may be formed so that a part of the connector  33  disposed at the mounting groove  3111   a  is exposed to the outside of the frame  311 . For example, in the mounting groove  3111   a , a fastening hole may be further formed, in which a means for fastening the connector  33  to the first support portion  3111  (not shown) can be fastened. 
     The second support portion  3112  may be extended from one end and the other end of the first support portion  3111  and bent in the width direction of the mask body  31  (the y-axis direction in  FIG. 2 ) at the lower portion of the mask body  31 . In other words, the second support portion  3112  may be extended downwardly from the ends of the mask body  31  in the height direction of the mask body  31  (the z-axis direction in  FIG. 2 ) into curves. In addition, the second support portion  3112  may include a first extension portion extended in the vertical direction from the ends of the first support portion  3111  and a second extension portion extended in the horizontal direction from the ends of the first extension portion so that the second support portion  3112  may face the user&#39;s side head and zygoma when the user wear it. Accordingly, the viewing hole  311   a  may be formed on the inner side of the first support portion  3111  and the second support portion  3112 , in which the user&#39;s eyes and nose may be accommodated. Although not shown in the drawings, the second support portion  3112  may have a structure that allows the length thereof to be adjusted along the height direction of the mask body  31  (the z-axis direction in  FIG. 2 ). At this time, a length adjusting member (not shown) for guiding the movement of the second support portion  3112  and fixing the second support portion  3112  after it is moved to a predetermined position may be disposed on the inner side of the first support portion  3111  and the second support portion  3112 . Accordingly, the user can adjust the length of the second support portion  3112  appropriately for the positions of her/his eyes and nose to thereby stably support the display assembly  10 . 
     For example, the frame  311  may be made of a plastic material or a carbon material which has a certain strength against bending. The frame  311  may include a plurality of through holes passing through the frame  311  in order to make the frame portion  311  lighter. It is, however, to be understood that the material of the frame  311  is not limited thereto. 
     The mask body  31  may further include a buffer portion  312 . 
     Referring to  FIGS. 17 and 18 , the buffer portion  312  may be disposed on one surface of the frame  311  facing the user&#39;s face and may support the user&#39;s face when the user wears the device so that the load of the display assembly  10  may be evenly distributed on the user&#39;s face. 
     For example, the buffer portion  312  may be implemented as a foam made of a PE material having a predetermined thickness. It is, however, to be understood that the material of the buffer portion  312  is not limited thereto. The buffer portion  312  may be made of other materials such as a sponge, a gel, a latex and an air foam as long as it can perform the same function. As shown in  FIG. 19 , the buffer portion  312  may be disposed on a surface of the frame  311  and may be disposed along the edge of the frame  311 . 
     The mask body  31  may further include an elastic member  313 . 
     Referring to  FIGS. 17 and 18 , the elastic member  313  may be made up of an elastic fabric material having elasticity to surround the frame  311  and the buffer portion  312  and may support the sensing means  32  to be described below. A buffer space  313   a  may be formed between the frame  311  and the buffer portion  312  disposed at the edge of the frame  311 . When the user puts on the device, the elastic member  313  is pressed against the user&#39;s forehead and is pushed toward the buffer space  313   a  while being stretched outwardly, such that it is elastically deformed into a shape conforming to the user&#39;s forehead. As a result, the sensing means  32  disposed inside the elastic member  313  can be elastically supported so that the sensing means  32  can be in tight contact with the user&#39;s forehead. For example, the elastic member  313  may be made of a material having a higher elastic modulus than that of the buffer portion  312 . The surface of the elastic member  313  may be formed of nylon, suede, etc. so as to reduce the frictional force when it comes in contact with the user&#39;s skin. 
     The second biometric data acquiring unit  30  may include the sensing means  32 . 
     Referring to  FIGS. 17 and 18 , the sensing means  32  is disposed on the of the mask body  31  that faces the user&#39;s face when the user wears the device, and is elastically supported by the elastic member  313  of the mask body  31  to be in contact with the user&#39;s skin. Accordingly, the sensing means  32  can sense the second biometric data, which is a biometric signal from the user. In addition, the sensing means  32  may be implemented as a disk-shaped electrode made of a metal material or a thin-film electrode printed on a flexible substrate, and may sense the biometric signal from the user when it is connected to the display assembly  10  and receives power. For example, the sensing means  32  may be disposed on one side of the mask body  31  by pressing or bonding it. The sensing means  32  may be further subjected to a process for EMI shielding (Electro Magnetic Interference Shield) for shielding electromagnetic waves. 
     That is to say, the head-mounted display device  1  may include the buffer portion  312  which is disposed on one side of the mask body  31  to support a user&#39;s face so that the load of the display assembly  10  is evenly distributed on the user&#39;s face, and an elastic member  313  which is formed of an elastic fabric material and is stretched outwardly when it is pressed against the user&#39;s forehead so that it comes in tight contact with the user&#39;s forehead. In this manner, the sensing means  32  can be in contact with the user&#39;s skin stably and reliably. In addition, the display assembly  10  can stably support the user&#39;s face, and thus it is possible to prevent the display assembly  10  from being deviated from the user&#39;s face as the user takes actions. In addition, as the sensing means  32  is in tight contact with the user&#39;s forehead, it is possible prevent a gap from being formed between the user&#39;s skin and the sensing means  32 , thereby preventing the sensing means  32  from being separated. In addition, the sensing means  32  is elastically supported to thereby reduce the pressure applied to the user&#39;s forehead, such that it is possible to avoid a mark or a pain on the user&#39;s skin. 
     The sensing means  32  may have a structure that can be brought into tight contact with the user&#39;s forehead by using its own elastic force. 
     Referring to  FIG. 20 , the sensing means  32  may be disposed at the mask body  31  and may have an elastically-supported structure so that it is moved linearly in one direction when an external force is applied from the outside to be compressed, and is moved linearly in the opposite direction to be restored to its original state by the elastic force when the external force is released. 
     The sensing means  32  having the elastically-supported structure will be described in more detail. 
     The sensing means  32  may include a support ring  321 , a guide housing  322 , an electrode  323  and an elastic support member  324 . The support ring  321  may be formed in a annular shape with a press-fit groove that is recessed toward the inner center and is disposed along the circumference, and may be disposed at the mask body  31 . For example, the support ring  321  may be disposed at the mask body  31  by pressing it. The guide housing  322  may be fastened to the inside of the support ring  321 , and a guide hole  322   a  may be formed along the center axis direction therein. A step for restricting the movement of the electrode  323  may be formed in the guide housing  322 . For example, threads that can be engaged with each other may be formed on the outer circumferential surface of the guide housing  322  and the inner circumferential surface of the support ring  321 , respectively. The electrode  323  may be disposed inside the guide housing  322  and linearly movable along the guide hole  322   a . The side and the other side of the electrode  323  may protrude out of the guide housing  322 , respectively. A protruding piece may be formed on one side of the electrode  323 , which is held by the step formed in the guide housing  322 . The elastic support member  324  may be disposed inside the guide housing  322  and may be in the form of a coil spring to elastically support the electrode  323 . 
     The sensing means  32  having the elastically-supported structure may be disposed at the elastic member  313  of the mask body  31  or at the buffer portion  312  disposed on the surface of the frame  311 . If the sensing means  32  is disposed at the buffer portion  312 , the buffer portion  312  may be formed in a shape conforming to the surface of the frame  311  so as to be in contact with the user&#39;s skin. 
     At this time, the elastic member  313  may not be disposed at the mask body  31 . 
     The sensing means  32  may face a user&#39;s frontal lobe region when the user wears the device to sense the user&#39;s brain wave signal. 
     Referring to  FIGS. 18 and 21 , the sensing means  32  may be disposed at positions where the user&#39;s forehead is located when the user wears the device. Specifically, the sensing means may be disposed at the positions that face the surface of the first support portion  3111  where the user&#39;s forehead is located when the user wears the device. More than one sensing means  32  may be disposed. More specifically, the sensing means  32  may include a ground, a reference, and measurement terminals (Channel 1 and Channel 2). For example, the ground and the reference may be disposed at positions corresponding to the center of the first support  3111  and may be spaced apart from each other by a predetermined distance in the height direction of the mask body  31  (the z-axis direction). The measurement terminals Channel 1 and Channel 2 may be disposed on one side and the other side of the first support portion  3111  in the width direction of the mask body  31  (the y-axis direction) such that they are symmetrically with respect to the center portion of the first support portion  3111  where the ground and the reference are located. For example, more than one measurement terminals (Channel 1 and Channel 2) may be arranged. 
     In addition, the sensing means  32  may be disposed at the position where the user&#39;s side head and zygoma are located when the user wears the device, so that the user&#39;s biological signal can be sensed. 
     Referring to  FIGS. 16 and 21 , the sensing means  32  may be disposed at positions that face the surface of the second support portion  3112  such that it faces the user&#39;s side head and zygoma when the user wears the device. The sensing means  32  in contact with the user&#39;s side head and zygoma may sense at least one of the user&#39;s photoplethysmogram (PPG), electrocardiogram (ECG), electromyography (EMG) and skin temperature. 
     Although not shown in the drawings, the sensing means  32  may be electrically connected to other sensing means in contact with a user&#39;s body part other than the face. Accordingly, biometric signals other than the above-described biometric signal can be additionally sensed. For example, the sensing means  32  connected to the other sensing means may additionally sense body fat (a bioelectrical impedance analysis or BIA), stress response (a galvanic skin response or GSR), etc. 
     The sensing means  32  may have a structure that allows its position to be adjusted inside the mask body  31 . 
     Referring to  FIG. 22 , a movement adjusting member  325  for guiding the movement of the sensing means  32  according to a user&#39;s operation may be disposed on the mask body  31 . The movement adjusting member  325  may be formed in a ring shape, and a guide hole  325   a  for guiding the movement of the sensing means  32  may be formed in the movement adjusting member  325 . Although the guide hole  325   a  is shown as an arc shape curved along the horizontal direction in  FIG. 22 , the shape of the guide hole  325   a  is not limited thereto. The shape of the guide hole  325   a  may be altered into a variety of shapes as long as it can guide the movement of the sensing means  32  in the horizontal or vertical direction. 
     The second biometric data acquiring unit  30  may further include the connector  33 . 
     Referring to  FIGS. 17 and 23 , the connector  33  may be disposed at the mask body  31  to be electrically connected to the sensing means  32 , and may be connected to the socket  1243  formed in the display assembly  10  to transmit at least one second biometric data sensed by the sensing means  32  to a control means (not shown). The connector  33  may be coupled to the socket  1243  of the display assembly  10  using a magnetic force. For example, the connector  33  may include a connector housing  331  disposed at the mask body  31 , a pin  332  electrically connected to the sensing means  32  and disposed at an inner central portion of the connector housing  331 , and a magnet  333  disposed around the pin  332 . The connector  33  can be coupled to the socket  1243  by the magnetic force only when the connector  33  is aligned with the center of the socket  1243 . Accordingly, the user can quickly connect the connector  30  with the socket. The connector  33  can be more stably fixed to the socket  1243  by the magnetic force. 
     As described above, according to the exemplary embodiment of the present disclosure, the head-mounted display device can not only provide a user with virtual reality image but also acquire biometric data from the user&#39;s face who is watching the virtual reality image to thereby check the user&#39;s cognitive and emotional conditions. Accordingly, it is possible to develop contents including various experience elements. Furthermore, it is possible to improve satisfaction of the user&#39;s experience by providing contents suitable for the user&#39;s current conditions in real-time. 
     Further, since the display body  12  is rotatably coupled to the strap portion  11  and the strap portion  11  is in the form of an annular structure which can be put on by one hand, the user can easily put it on and take it off to look around as desired. As a result, the convenience can be improved. 
     Further, the display body  12  can be stably fixed to the user&#39;s face by the annular strap portion  11  in the form of the structure. Furthermore, even if the user takes a strenuous action during the experience, it is possible to prevent the display body  12  from being deviated from the user&#39;s face. 
     Further, as the mask body  31  supporting the user&#39;s face can be detached from the display body  12 , it is possible to easily replace the mask body  31 , thereby increasing the lifetime of the device while saving the cost. 
     Although the preferred embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims. Accordingly, such modifications, additions and substitutions should also be understood to fall within the scope of the present invention. 
     INDUSTRIAL APPLICABILITY 
     The head-mounted display device according to the exemplary embodiment of the present disclosure can be used in industrial fields such as games, education, national defense, medical care, etc., in which spatial and temporal experiences similar to the reality can be realized.