Abstract:
A user changes the shapes of the side frames from the shapes at the positions indicated by dashed lines at which no external force is applied to those at the positions indicated by dashed lines, and mounts the side frames on the head. As a result, the side frames and rear mount pads perfectly fit on the head, as indicated by solid lines. The user therefore can see video on a main body of a display unit in a natural state without any strain.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a head mount display having a visual apparatus to be mounted on the head of a user to allow him/her to see video. 
     2. Related Background Art 
     A visual apparatus called a head mount display that is mounted on the head of a user to allow him/her to see the video displayed on a display unit is disclosed in Japanese Patent Application Laid-Open Nos. 7-84210, 7-181422, and 7-333547. This head mount display is used to enjoy video or the like with a sense of reality in an arbitrary place without influencing the surroundings, and hence is required to be lightweight, comfortable to wear, and excellent in portability. 
     (1) The head mount display in Japanese Patent Application Laid-Open No. 7-84210 is a mount apparatus having a mount portion whose rear portion is cut. According to this apparatus, a press support member using an elastic member made of a metal, synthetic resin, or the like is pressed against the head of the user. With this operation, the user can wear the apparatus comfortably without any restraint felt at the back of the head. In addition, the apparatus can be easily attached/detached on/from the head of the user from the front. 
     (2) The head mount display in Japanese Patent Application Laid-Open No. 7-181422 is designed such that the mount unit surrounds the head of the observer. This mount unit is biased to the sides of the head to fix it on the head. 
     (3) The video display apparatus in Japanese Patent Application Laid-Open No. 7-333547 has a display unit mounted on a mount frame, and a movable frame mounted on the mount frame. With this structure, this movable frame is biased to fix the apparatus on the head of the user. 
     FIG. 15 is a side view of another conventional head mount display. An image display unit  101  is coupled to a mount member  103  through a support member  102  having two hinges  102   a  and  102   b . A forehead pad  104  is mounted on the mount member  103 . The forehead pad  104  is comprised of a pad  105   a , a pad base  105   b , and a base  106 . 
     When this apparatus is to be used, the mount member  103  is mounted on an observer S, and the pad  105   a  of the forehead pad  104  is brought into contact with the forehead of the observer. In this case, visual axis adjustment between the image display unit  101  and an eyeball of the observer is performed by using the two hinges  102   a  and  102   b.    
     SUMMARY OF THE INVENTION 
     According to the conventional head mount display (1), although easy mounting and elimination of discomfort from the head can be realized, the pressing force adjustment mechanism attached to the press support member increases the weight of the apparatus and hampers comfort in wearing the apparatus. In addition, owing to the frame partly cut and shaped to surround the head, the apparatus becomes large in size. This interferes with portability that allows the user to enjoy video in an arbitrary place. 
     In addition, since the press support member made of an elastic member such as a metal or synthetic resin member is pressed against the head to fix the apparatus on the head, if a synthetic resin or the like is used, the press support member creeps after a long period of use, and the biasing force needs to be sequentially adjusted. Eventually, the necessary biasing force may not be obtained. Assume that a metal is used for the press support member. In this case, since no caution is exercised in selecting the material and cross-sectional shape, if the press support member is spread when the user wears the apparatus on his or her head, the internal stress exceeds the elastic limit, resulting in a loss of biasing force. Likewise, adjustment for spring force is sequentially required, and the necessary biasing force may not be obtained eventually. 
     According to the head mount display (2), since the display unit is fixed on the head of the observer with the headband-like mount unit, it is troublesome to properly wear the apparatus. In addition, the display unit is relatively heavy, and the display unit must be fixed on the head with a strong force. This gives the observer a sense of restraint, and the observer&#39;s hair curls in a wrong way when he/she wears the apparatus. 
     The video display apparatus (3) can be mounted on the head of the user from the front of the face and hence has good portability. Since this apparatus does not compress the entire perimeter of the head, no sense of restraint is locally produced. However, the movable frame is biased against the head, and the mount frame receives the repulsion of the basing force. For this reason, the mount frame must have high rigidity. As a result, the frame becomes heavy, impairing the comfort upon wearing the apparatus. 
     It is an object of the present invention to provide a lightweight head mount display which solves the above problems, can be easily mounted on the head of a user, and has high portability. 
     In order to achieve the above object, a head mount display comprising a display unit having a display element and optical means for enlarging/displaying an image on the display element, a first frame extending substantially conforming to a forehead of a user, first support portion mounted on the first frame at a predetermined angle, and support means for supporting the display unit on the first frame, wherein the first frame is formed by bending a metal rod, metal pipe, or metal plate, first and second hinges are mounted on two end portions of the first frame, the other end of each of the first and second hinges supports a corresponding one of first and second side frames, which respectively have second and third support portions, have shapes bent inwardly, and have elasticity in a direction in which the first and second side frames bend, to allow each of the side frames to rotate in a direction of the head, and the first, second, and third support portions are biased with biasing forces produced by spreading the first and second side frames, thereby producing a force that allows the pads to be worn on the head. 
     According to the present invention, there is provided a head mount display comprising a display unit having a display element and optical means for enlarging/displaying an image on the display element, a first frame extending substantially conforming to a forehead of a user, first support portion mounted on the first frame at a predetermined angle, and support means for supporting the display unit on the first frame, wherein the first frame is formed by coating a core member obtained by bending a metal rod, metal pipe, or metal plate with a resin film, first and second hinges are mounted on two end portions of the first frame, the other end of each of the first and second hinges supports a corresponding one of first and second side frames, which respectively have second and third support portions, have shapes bent inwardly, and have elasticity in a direction in which the first and second side frames bend, to allow each of the side frames to rotate in a direction of the head, and the first, second, and third support portions are biased with biasing forces produced by spreading the first and second side frames, thereby producing a force that allows the pads to be worn on the head. 
     According to the present invention, there is provided a head mount display comprising a display unit having a display element and optical means for enlarging/displaying an image on the display element, a first frame extending substantially conforming to a forehead of a user, first support portion mounted on the first frame at a predetermined angle, and support means for supporting the display unit on the first frame, wherein the first frame is formed by bending a metal rod, metal pipe, or metal plate, first and second hinges are mounted on two end portions of the first frame, the other end of each of the first and second hinges supports a corresponding one of first and second side frames, which have shapes bent inwardly and have elasticity in a direction in which the first and second side frames bend, to allow each of the side frames to rotate in a direction of the head, the first and second side frames respectively have third and fourth hinges mounted on end portions different from the end portions coupled to the first and second hinges, first and second press members respectively having second and third support portions are respectively supported on the third and fourth hinges to be rotatable in a direction of the head, and the first, second, and third support portions are biased with biasing forces produced by spreading the first and second side frames, thereby producing a force that allows the pads to be worn on the head. 
     According to the present invention, there is provided a head mount display comprising a display unit having a display element and optical means for enlarging/displaying an image on the display element, a first frame extending substantially conforming to a forehead of a user, first support portion mounted on the first frame at a predetermined angle, and support means for supporting the display unit on the first frame, wherein the first frame is formed by bending a metal rod, metal pipe, or metal plate, first and second hinges are mounted on two end portions of the first frame, the other end of each of the first and second hinges supports a corresponding one of first and second side frames, which have shapes bent inwardly and have elasticity in a direction in which the first and second side frames bend, to allow each of the side frames to rotate in a direction of the head, the first and second side frames respectively have first and second elastic members mounted on end portions different from the end portions coupled to the first and second hinges, first and second press members respectively having second and third support portions are respectively supported on the first and second elastic members to be foldable in a direction of the head, and the first, second, and third support portions are biased with biasing forces produced by spreading the first and second side frames, thereby producing a force that allows the pads to be worn on the head. 
     The head mount display that obtains a biasing biasing force of the elastic side frames can be made lightweight as a whole, and comfortable to wear. In addition, this apparatus is easy to wear and realizes excellent portability. 
     The head mount display uses the side frames coated with a resin and hence gives the user a soft feel when the support portion comes into contact with the head of the user. Even a person having an allergy to metals can use the display for a long period of time. 
     The head mount display having the frames and press member that can be folded in two is comfort to wear. This apparatus can be folded into a very compact structure and hence can improve the portability. 
     The head mount display designed to be folded in two by using the elastic members and press members is more comfortable to wear. This apparatus can be folded into a compact structure and hence can improve the portability. 
     The conventional apparatus shown in FIG. 15 uses one hinge  102   b  to adjust the visual axis height between the image display unit  101  and the eyeball. If the visual axis of the observer S matches a position where the forehead pad  104  approaches the displayed image in terms of height, the image display unit  101  pivots on the hinge  102   a  on the mount member  103  side to move to the position indicated by a chain double-dashed line  101 ′ away from the eyeball. As a result, the weight moment of the image display unit  101  increases to give the observer S a sense of heaviness, and the observer will suffer from fatigue after a long period of use. 
     When a plurality of observers S are to use one display apparatus, each observer S must adjust the visual axis height every time he/she uses it in order to adjust the visual height in accordance with each observer S. This is inconvenient when each observer wants to immediately observe video. In addition, even if only one observer S is to use the apparatus, the visual axis height easily goes out of adjustment upon reception of an external force or the like. 
     It is another object of the present invention to provide a head mount display apparatus which solves the above problems and can be worn stably without changing the weight moment by keeping the distance between the eyeballs and the forehead pad constant. 
     In order to achieve this object, according to the present invention, there is provided a head mount display apparatus comprising a display unit including a display element and optical means for enlarging and displaying an image on the display element, and mount means for mounting the display unit on a front surface of a head of a user, wherein the mount means has a mount pad that comes into contact with a forehead of the user at least upon being mounted, and the mount pad is movable in a direction of height with respect to the display unit to allow adjustment of a position where the mount pad comes into contact with the forehead of the user. 
     In addition, according to the present invention, there is provided a head mount display apparatus comprising a display unit including a display element and optical means for enlarging and displaying an image on the display element, and mount means for mounting the display unit on a front surface of a head of a user, wherein the mount means has a mount frame supporting the display unit and a mount pad that is supported by the mount frame and comes into contact with a forehead of the user upon being mounted, and the mount pad is movable in a direction of height with respect to the display unit to allow adjustment of a position where the mount pad comes into contact with the forehead of the user. 
     In using the head mount display apparatus, the user can adjust the visual axis between the image display unit and the eyeballs by vertically moving the mount pads without moving the display unit. The user can therefore adjust the visual axis optimally and easily while observing the image. Since the display unit does not move back and force with respect to the user, the distance between the eyeballs and the mount means is kept constant, and the user can wear it stably without any change in weight moment. In addition, since the visual axis adjustment unit can be assembled from a small number of parts, reductions in the number of assembly steps and weight can be attained. This apparatus can maintain an optimal visual axis adjustment position for the user for a long period of time with easy adjustment. 
     Furthermore, when this head mount display apparatus is to be used by a plurality of users, even if the display unit is not adjusted to the optimal position for the eyes of each user, he/she can easily re-adjust the display unit to the optimal adjustment position for his/her eyes. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of the first embodiment of the present invention; 
     FIG. 2 is a plan view of the embodiment; 
     FIG. 3 is a side view of the embodiment in a mounted state; 
     FIG. 4 is a side view of a side frame; 
     FIG. 5 is a plan view of the side frame; 
     FIG. 6 is a perspective view of the second embodiment of the present invention; 
     FIG. 7 is a plan view of the third embodiment of the present invention; 
     FIG. 8 is a plan view of the embodiment in a folded state; 
     FIG. 9 is a sectional view of the fourth embodiment before visual axis adjustment; 
     FIG. 10 is a front view of the embodiment; 
     FIG. 11 is a front view of the embodiment in a knob adjustment state; 
     FIG. 12 is a sectional view of the embodiment after visual axis adjustment; 
     FIG. 13 is a front view of the embodiment; 
     FIG. 14 is a perspective view of the fifth embodiment of the present invention; and 
     FIG. 15 is a side view of the display unit of the prior art. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The present invention will be described in detail below with reference to the accompanying drawings. 
     FIG. 1 is a perspective view of the first embodiment. A main body  1  of a display unit incorporates a backlight, a liquid crystal panel, a display circuit, and an optical means. The main body  1  is fixed to a front frame  3  with screws, by brazing, or the like through a support member  2  made of, e.g., a synthetic resin or titanium. For example, the front frame  3  is formed by bending a titanium rod member to have a shape almost conforming to the front surface of the head of a user S, as shown in FIGS. 2 and 3. The support member  2  is fixed to substantially the middle of the front frame  3  with screws or the like. In addition, hinges  4 L and  4 R are fixed to the two ends of the front frame  3  by brazing, caulking, or the like. 
     The support member  2  has pivots  2   a  and  2   b  at two positions. The main body  1  is axially supported by the pivot  2   a  to be rotatable back and forth with a predetermined frictional force with respect to the user S. For example, two front mount pads  5  are axially supported by the pivot  2   b  to be pivotal vertically within a predetermined angular range with respect to the user S. A spring (not shown) is hooked between the support member  2  and the front mount pads  5  so the front mount pads  5  is biased downward, with respect to the user, around the pivot  2   b  of the support member  2 . 
     Each of side frames  6 L and  6 R made of, e.g., a stainless steel alloy, titanium, a titanium alloy, or a super-elastic alloy is coupled to the other end of a corresponding one of the hinges  4 L and  4 R. The side frames  6 L and  6 R are bent in the form indicated by dashed lines A in FIG. 2 before the frames are mounted on the head of the user. The side frames  6 L and  6 R are axially supported by the hinges  4 L and  4 R to be pivotal within predetermined angular ranges with respect to the front frame  3 . Each of rear pads  7 L and  7 R is mounted on the other end of a corresponding one of the side frames  6 L and  6 R. 
     The hinges  4 L and  4 R are mounted at positions where the side frames  6 L and  6 R are located on the extended lines of the front frame  3  and the two end faces of the front frame  3  come into contact with the end faces of the side frames  6 L and  6 R. The side frames  6 L and  6 R cannot be spread outwardly from the extended lines of the front frame  3  but can be folded inwardly. 
     The side frames  6 L and  6 R are shaped to be softer and more elastic than the front frame  3 . More specifically, as shown in FIG. 4, each of the hinges  4 L and  4 R gradually decreases in height h rearward toward the position at which it is fixed. In addition, as shown in FIG. 5, each of the hinges  4 L and  4 R gradually increases in thickness t rearward toward the position at which it is fixed. 
     Furthermore, a cable  8  extending from a video tape deck, personal computer, or the like (not shown) is connected to the main body  1 . The cable  8  is fixed to the side frame  6 L with a hook  9 . 
     At the positions indicated by the dashed lines A in FIG. 2, no external force acts on the side frames  6 L and  6 R. When the user S wants to wear the side frames  6 L and  6 R, he/she change the shapes of the side frames  6 L and  6 R from those at these positions to those at the positions indicated by dashed lines B in FIG.  2 . At this time, the front frame  3  hardly deforms because it has higher rigidity than the side frames  6 L and  6 R. In addition, internal stress is produced in the side frames  6 L and  6 R to become a biasing force. However, since the cross-sectional areas of the portions of the side frames  6 L and  6 R which are located near the hinges  4 L and  4 R are larger than those of the portions of the side frames  6 L and  6 R which are located far from the hinges  4 L and  4 R, this internal stress is dispersed. This prevents the sprint properties of the side frames  6 L and  6 R from being impaired beyond the elastic limit. 
     When the user S wears the head mount display, the side frames  6 L and  6 R and the rear pads  7 L and  7 R are located at the positions indicated by the solid lines in FIG.  2 . As a result, the head mount display fits on the head of the user S, as shown in FIG.  3 . If a person having a small head wears this display, the pressure on the head decreases so the display may become loose. In contrast to this, if a person having a large head wears the display, the pressure becomes so high that the user has a headache. However, these problems can be solved by using a material having a low Young&#39;s modulus and a high elastic limit, such as a stainless steel alloy, titanium, a titanium alloy, or a super-elastic alloy for the side frames  6 L and  6 R. Any user can therefore wear the display comfortably to his/her satisfaction regardless of the size of the head. In addition, the user can carry this display with the side frames  6 L and  6 R being folded inward at the hinges  4 L and  4 R, thus making the overall apparatus compact in size. 
     The user S wears this head mount display to watch video displayed on the main body  1  on the basis of a signal from a video signal generating means such as a video tape deck. 
     FIG. 6 is a perspective view of the second embodiment. In this embodiment, the front frame  3  and the side frames  6 L and  6 R of the second embodiment are coated with an elastomer or the like. The same reference numerals in the second embodiment denote the same parts as in the first embodiment. A coating frame  11  is formed on a front frame  3  by insert molding with polyester elastomer. Likewise, coating frames  12 L and  12 R are formed on side frames  6 L and  6 R by insert molding with polyester elastomer. Each of the side frames  6 L and  6 R is coated with the elastomer and bent to have a predetermined biasing force. 
     With this arrangement, since no metal portion protrudes outside, the frames come into contact with the head with a soft feel. Even if, therefore, a person having an allergy to metals wears the display for a relatively long period of time of several tens of minutes to several hours, he/she can safely use the display without any problem. In addition, if a hook  9  for fixing a cable is integrally formed on the coating frame  12 L, the display appears tidy in terms of design and function. This increases the degree of freedom in design and can realize a smart appearance that gives the user confidence in terms of strength. Furthermore, if the side frames  6 L and  6 R and the coating frames  12 L and  12 R are integrally formed by molding with an elastomer or the like, the overall weight of the apparatus can be decreased. 
     FIG. 7 is a plan view schematically showing the third embodiment. The same reference numerals in this embodiment denote the same parts as in the first embodiment. The side frames  6 L and  6 R of the first embodiment are divided into first side frames  21 L and  21 R and second side frames  22 L and  22 R. These frames are coupled to each other through second hinges  23 L and  23 R. For example, the side frames  21 L,  21 R,  22 L, and  22 R are made of a stainless steel alloy, titanium, a titanium alloy, or a super-elastic alloy and are bent inwardly to the direction of the head. One end of each of the first side frames  21 L and  21 R is axially supported by a corresponding one of first hinges  4 L and  4 R to be pivotal within a predetermined angular range with respect to a front frame  3 . The other end of each of the first side frames  21 L and  21 R is axially supported by a corresponding one of the second hinges  23 L and  23 R to be rotatable within a predetermined angular range with respect to a corresponding one of the first side frames  21 L and  21 R. 
     The first hinges  4 L and  4 R are mounted at positions where the first side frames  21 L and  21 R are located on the extended lines of the first hinges  4 L and  4 R and the end faces of the front frame  3  come into contact with the end faces of the first side frames  21 L and  21 R. The first side frames  21 L and  21 R cannot be spread outwardly from the extended lines of the front frame  3  but can be folded inwardly. 
     Likewise, the second hinges  23 L and  23 R are mounted at positions where the second side frames  22 L and  22 R are located on the extended lines of the first side frames  21 L and  21 R and the end faces of the first side frames  21 L and  21 R come into contact with the end faces of the second side frames  22 L and  22 R. The second side frames  22 L and  22 R cannot be spread outwardly from the extended lines of the first side frames  21 L and  21 R but can be folded inwardly. 
     When the user wants to wear the head mount display, he/she unfolds the first and second side frames  21 L,  21 R,  22 L, and  22 R that are bent inwardly, and fixes the display on his/her head while rear pads  7 L and  7 R press the head with, in particular, the biasing force generated by the second side frames  22 L and  22 R. 
     When the head mount display is not used, the first and second side frames  21 L,  21 R,  22 L, and  22 R can be folded inwardly at the first hinges  4 L and  4 R and the second hinges  23 L and  23 R, as shown in FIG.  8 . This makes the display compact and improves the portability. 
     In place of the first side frames  21 L and  21 R, other elastic members, e.g., rubber or spring members, can be used. 
     FIGS. 9 to  13  show the fourth embodiment. FIG. 9 is a sectional view of the embodiment before visual axis adjustment. FIG. 10 is a front view of the embodiment. FIG. 11 is a front view of the embodiment in the process of visual axis adjustment. FIG. 12 is a sectional view of the embodiment after visual axis adjustment. FIG. 13 is a front view of the embodiment. A display unit  111  of the head mount display incorporates a prism  112  including a total reflection mirror, an image display means  113 , an illumination means  114 , and an electric circuit board  115 . The electric circuit board  115  is connected to the image display means  113  and the illumination means  114  through a wire harness, flexible cable, or the like. A mount frame  116  that supports the display unit  111  is made of an elastic material such as a metal or synthetic resin. If a metal is used, heat can be dissipated from the display unit  111 . The display unit  111  is held on a hinge portion  117  and coupled to the mount frame  116  to be vertically pivotal. 
     A base  118  is mounted on the mount frame  116 . The base  118  is fixed with screws or an adhesive, by welding, or the like. If the mount frame  116  is a molded product made of a synthetic resin, the mount frame  116  and the base  118  can be integrally molded. The base  118  has a frame-like shape with a plurality of recesses formed in its inner surface. In addition, marks such as the numbers 1, 2, and 3, the letters A, B, and C, or the like may be printed or inscribed on a portion near the recesses/projections of the base  118 . 
     A forehead pad  119  is fixed to the base  118 . The forehead pad  119  is comprised of a pad  119   a  made of an elastic material such as a rubber or foamed sponge material and a pad base  119   b . The pad  119   a  and the pad base  119   b  are joined to each other with an adhesive, double-sided adhesive tape, or the like. The pad base  119   b  has two projections  119   c  that conform to the recesses/projections in the inner surface of the base  118  and engage with the recesses/projections of the base  118  to be held. Two adjustment knobs  120  are formed near the projections of the base  118 . To move the forehead pad  119 , the user exerts external forces on the adjustment knobs  120  in the directions in which the adjustment knobs  120  come close to each other. As a result, as shown in FIG. 11, the projections  119   c  of the pad base  119   b  move from the recesses/projections of the base  118  and engage with arbitrary recesses/projections of the base  118 , as shown in FIGS. 12 and 13. 
     Assume that an observer S wants to adjust the image display unit to the upper visual axis after he/she wears the display. In this case, the observer moves the display unit  111  upward by moving the forehead pad  119  upward with respect to the base  118 , thereby adjusting the display unit  111 . The image displayed on the image display means  113  is illuminated by the illumination means  114 . This image light strikes the prism  112  including the total reflection mirror. As a result, an enlarged virtual image reaches an observer&#39;s eye E, and the observer S can visually check the enlarged image with an optimal visual axis. 
     FIG. 14 is a perspective view of the fifth embodiment. In the fourth embodiment, the forehead pad  119  slides on the display unit  111 . In the fifth embodiment, the forehead pad is divided into two parts, which are pivoted to change the vertical positions of the display unit and the forehead pads. 
     A display unit  121  incorporates a backlight, a liquid crystal panel, a display circuit, and an optical means. The display unit  121  is mounted on a mount frame  122  through a support member  123 . The output of the display unit  121  is connected to a signal source such as a video tape deck or personal computer (not shown) through a cable  124 . The cable  124  is fixed to the mount frame  122  with a hook  125 . For example, the mount frame  122  is formed by bending a titanium rod member and has a shape almost conforming to the front surface of the head of a user. The support member  123  made of a synthetic resin or titanium is fixed to substantially the middle of the mount frame  122  with screws or the like. First and second hinges  126  and  127  are mounted on the two ends of the mount frame  122  by brazing, caulking, or the like. 
     The support member  123  has first and second rotating shafts  123   a  and  123   b . The first rotating shaft  123   a  axially supports the display unit  121  to allow it to rotate back and forth with a predetermined frictional force. The second rotating shaft  123   b  axially supports first and second forehead pads  128  and  129  through pivots  128   a  and  129   a  to allow the pads to vertically pivot within predetermined angular ranges. The pivots  128   a  and  129   a  allow the first and second forehead pads  128  and  129  to pivot within a plane roughly perpendicular to the visual axis. The pivots  128   a  and  129   a  are supported by clicks or the like such that their positions are selectively determined. 
     Each of first and second cranes  130  and  131  made of stainless steel alloy, titanium, a titanium alloy, or a super-elastic alloy is coupled to the other end of each of hinges  126  and  127 . The hinges  126  and  127  respectively allow the cranes  130  and  131  to rotate within predetermined angular ranges with respect to the mount frame  122 . In addition, each of first and second pads  132  and  133  for the back of the head is mounted on the other end of each of the cranes  130  and  131 . 
     The first and second hinges  126  and  127  are mounted at positions where the first and second cranes  130  and  131  are located on the extended lines of the mount frame  122  and the end faces of the mount frame  122  come into contact with the end faces of the first and second cranes  130  and  131 . The first and second cranes  130  and  131  cannot be spread outwardly from the extended lines of the mount frame  122  but can be folded inwardly. 
     With this arrangement, the user can easily wear the display unit  121  like glasses. If the user wearing the display feels that the visual axis does not match the height of the display unit  121 , he/she selects and sets the rotating positions of the first and second forehead pads  128  and  129  to proper positions, thereby practically changing the vertical positions at which the forehead pads  128  and  129  come into contact with the forehead of the user. This allows the forehead pads to conform to the shape of the face or head of any user. When video based on an electrical signal from a video signal generating means such as a video tape deck (not shown) is displayed on the display unit  121  after the position of the display unit  121  is adjusted to the optimal position in this manner, the observer can see the enlarged video.