Patent Publication Number: US-2011058317-A1

Title: Height adjusting mechanism for electronic device and electronic device provided with the same

Description:
TECHNICAL FIELD 
     The present invention relates to a height adjusting mechanism used for adjusting the height of an electronic device and an electronic device provided with the same. 
     BACKGROUND ART 
     Some electronic devices, like a projector, for example, for projecting an image on the projection plane such as a screen, need to adjust their height when used. Such electronic devices are generally provided with height adjusting mechanisms having a support leg. Projectors provided with height adjusting mechanisms having a support leg can adjust image projecting positions by varying the length of the support leg to change the height to the surface on which the projector is placed or to change the angle of projection. 
     Some height adjusting mechanisms are called as “crew type”, the crew type height adjusting mechanisms have a support leg which has a screw rod inserted into a tapped hole formed on the bottom plate of the housing of an electronic device. The screw type height adjusting mechanism is configured such that a support leg is rotated in order to vary the amount of a screw rod inserted to the tapped hole for allowing the length of the support leg extending below the bottom surface of a housing to be changed. 
       FIG. 1  is a cross sectional view depicting a screw type height adjusting mechanism related to the invention of the present application, and  FIG. 2  is an exploded perspective view depicting the height adjusting mechanism shown in  FIG. 1 . 
     Height adjusting mechanism  101  includes fixing portion  103   a  provided on housing  103  of an electronic device and having through hole  103   b  defined therein, tapped member  102  having tapped hole  102   a  therein and adapted to be fixed inside through hole  103   b,  and support leg  104  having screw rod  104   a  adapted to be inserted into tapped hole  102   a  in tapped member  102 . Leg part  104   b  for supporting the electronic device is disposed at the lower end portion of screw rod  104   a.    
     For height adjusting mechanism  101 , support leg  104  is rotated in order to vary the amount of screw rod  104   a  inserted into tapped member  102  for allowing the length of support leg  104  extending below the bottom surface of housing  103  to be changed. 
     Housing  103  is made of a resin material for reducing the entire weight of the electronic device and production costs, and fixing portion  103   a  is formed in one piece with housing  103 . On the other hand, screw rod  102  is made of a metal material. 
     For the screw type height adjusting mechanism, a metal screw rod is generally used. Because it is sometimes difficult for the metal screw rod to sufficiently mate with the tapped hole that is directly formed in the resin housing, a metal tapped member that is engaged with the screw rod is mounted in a through hole formed on the housing. For the tapped member, a metal nut or a metal plate formed with a tapped hole therein is used. The metal nut is fixed by being press-fit into the through hole formed on the housing and thermally welded thereto, whereas the metal plate formed with the tapped hole is fixed by being screwed to inner surface of the housing. 
     In height adjusting mechanism  101 , a metal nut is used for tapped member  102 . In mounting work, tapped member  102  is press-fit into through hole  103   b  in fixing portion  103   a  with a press-fit tool while being heated, and tapped member  102  is thermally welded to the inner wall surface of through hole  103   a.  Further, in height adjusting mechanism  101 , because tapped member  102  is thermally welded to the inner wall surface of through hole  103   a,  it is necessary to use a tool or the like to remove tapped member  102  from housing  103  in disassembly operation for recycle. As described above, height adjusting mechanism  101  takes time and effort in mounting and dismounting work. 
     JP2007-173469A describes a height adjusting mechanism that solves these disadvantages. In this height adjusting mechanism, an elastically deformable engagement portion is provided in a tapped member, and the tapped member can be inserted into the through hole formed in the fixing portion in a state in which the engagement portion is elastically deformed. The tapped member inserted into the through hole is vertically fixed to the fixing portion by allowing the engagement portion to engage with the fixing portion. Furthermore, because the tapped member inserted into the through hole is formed so as to cover the entire circumference of the through hole with no clearance, the engagement portion of the tapped member is not removed from the fixing portion and is held in the through hole. 
     Consequently, in this height adjusting mechanism, in assembly operation, the tapped member is inserted into the through hole formed in the fixing portion by elastically deforming the engagement portion, and accordingly it is made possible to readily fix the tapped member to the fixing portion. In addition, in disassembly operation, the engagement of the engagement portion with the fixing portion is released by elastically deforming the engagement part, and consequently readily removing the tapped member fixed to the fixing portion from the fixing portion is made possible. 
     However, in the height adjusting mechanism described in JP2007-173469A, because a housing is made of a resin material, it is elastically deformed by an external impact or the like. Because the tapped member is not fixed to the fixing portion in the radial direction of the through hole, when the fixing portion in the housing is elastically deformed, a clearance can sometimes be created between the tapped member and the inner wall surface of the through hole. On this account, it can be considered that the engagement portion comes off from the fixing portion to cause the tapped member to fall off from the through hole. 
     SUMMARY OF THE INVENTION 
     An object of the present invention is to provide a height adjusting mechanism that can facilitate operation to assemble and disassemble and that can stably support an electronic device. 
     A height adjusting mechanism according to the present invention includes a fixing portion having a through hole formed therein; a tapped member having a thread groove formed thereon, wherein a rear side, which is the reverse side of a surface on which the thread groove is formed, covers at least a part of an inner wall surface of the through hole; and a support leg having a screw rod formed with a thread ridge formed thereon in a longitudinal direction, the screw rod being inserted into the through hole such that the thread ridge is in engaging relation with the thread groove, wherein the fixing portion and the tapped member are engaged with each other to cause the tapped member to be fixed to the fixing portion in a penetrating direction of the through hole and in a radial direction of the through hole. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a cross sectional side view depicting a height adjusting mechanism related to the invention of the present application; 
         FIG. 2  is an exploded perspective view depicting the height adjusting mechanism shown in  FIG. 1 ; 
         FIG. 3  is a cross sectional side view depicting a height adjusting mechanism according to a first embodiment of the present invention; 
         FIG. 4  shows perspective views depicting a tapped member of the height adjusting mechanism shown in  FIG. 3 ; 
         FIG. 5  is an exploded perspective view depicting the height adjusting mechanism shown in  FIG. 3 ; and 
         FIG. 6  is a side view depicting an electronic device according to a second embodiment of the present invention. 
     
    
    
     BEST MODE FOR CARRYING OUT THE INVENTION 
     Next, embodiments of the present invention will be described with reference to the drawings. 
     First embodiment 
     First, a height adjusting mechanism according to a first embodiment of the present invention will be described with reference to  FIGS. 3 to 6 .  FIG. 3  is a cross sectional side view depicting the height adjusting mechanism according to the first embodiment of the present invention. 
     Height adjusting mechanism  1  includes fixing portion  3   a  that is disposed on housing  3  of an electronic device and that has through hole  3   b  formed therein, tapped member  2  that is mounted on fixing portion  3   a  so as to cover a part of the inner wall surface of through hole  3   b , and support leg  4  that has screw rod  4   a  adapted to be inserted into through hole  3   b  in fixing portion  3   a.  Leg part  4   b  for supporting the electronic device is disposed at the lower end portion of screw rod  4   a.    
     Fixing portion  3   a  is made of a resin material and formed in one piece with housing  3 . Tapped member  2  is formed with thread groove  12  therein, and screw rod  4   a  is formed with thread ridge  14  in the longitudinal direction. A part of thread ridge  14  formed over the entire circumference of screw rod  4   a  and thread groove  12  formed inside tapped member  2  are engaged with each other to allow screw rod  4   a  to hold tapped member  2 . 
     In height adjusting mechanism  1 , support leg  4  is rotated in order to vary the amount of screw rod  4   a  inserted into through hole  3   b,  and consequently the length of the portion of support leg  4  extending below the bottom surface of housing  3  can be changed. 
       FIG. 4  shows perspective views depicting the tapped member of the height adjusting mechanism according to the embodiment.  FIG. 4(   a ) shows tapped member  2  on thread groove  12  side, and  FIG. 4(   b ) shows the rear side of tapped member  2 , which is the reverse side of thread groove  12 . At the upper and lower end portions of tapped member  2 , engagement portions  12   a  and  12   b  extended to the rear side are disposed, respectively. First engagement holes  22   a  and  22   b  are respectively formed in engagement portions  12   a  and  12   b.  Further, second engagement hole  22   c  is formed on the rear side which opposite to the face on which thread groove  12  of tapped member  2  is formed. 
       FIG. 5  is an exploded perspective view depicting the height adjusting mechanism according to the embodiment.  FIG. 5  shows housing  3  is partially omitted. First projecting portions  13   a  and  13   b  are formed on the top surface and the under surface of fixing portion  3   a  in housing  3 , respectively. Also, second projecting portion  13   c  is formed on the inner wall surface of through hole  3   b  in fixing portion  3   a.    
     Tapped member  2  is mounted on fixing portion  3   a  such that the rear side covers a part of the inner wall surface of through hole  3   b  and engagement portion  12   a  and engagement portion  12   b  come into contact with the top surface and the under surface of fixing portion  3   a , respectively. Consequently, in height adjusting mechanism  1 , tapped member  2  is vertically fixed to fixing portion  3   a.    
     Furthermore, in height adjusting mechanism  1 , projecting portions  13   a  and  13   b  of fixing portion  3   a  and engagement holes  22   a  and  22   b  of tapped member  2  are engaged with each other, respectively, and projecting portions  13   a  and  13   b  of fixing portion  3   a  are then inserted into engagement holes  22   a  and  22   b  of tapped member  2 , respectively, in the penetrating direction of through hole  3   b.  Consequently, tapped member  2  is fixed to fixing portion  3   a  also in the radial direction of through hole  3   b.    
     In addition, in height adjusting mechanism  1 , projecting portion  13   c  of fixing portion  3   a  and engagement hole  22   c  in tapped member  2  are engaged with each other, and projecting portion  13   c  on the inner wall surface of through hole  3   b  is then inserted into engagement hole  22   c  in tapped member  2  in the radial direction of through hole  3   b.  Accordingly, eliminating such an event in which tapped member  2  moves along the inner wall surface of through hole  3   b  is made possible. In this situation, such an event in which engagement portions  12   a  and  12   b  are elastically deformed to cause engagement holes  22   a  and  22   b  to come off from projecting portions  13   a  and  13   b  can be prevented. Additionally, because the load born from fixing portion  3   a  onto engagement portions  12   a  and  12   b  can be reduced, it also become possible to prevent engagement portions  12   a  and  12   b  from being damaged. 
     As described above, in height adjusting mechanism  1 , even though housing  3  is elastically deformed due to an external impact or the like, the electronic device can be stably supported because engagement portions  12   a  and  12   b  do not tend to be removed from fixing portion  3   a.    
     Further, in height adjusting mechanism  1 , in assembly operation, engagement portion  12   a  and  12   b  are placed so as to come into contact with the top surface and the under surface of fixing portion  3   a,  respectively, and therefore, readily mounting tapped member  2  on fixing portion  3   a  becomes possible. Furthermore, in disassembly operation, the engagement of projecting portions  13   a  and  13   b  of fixing portion  3   a  with engagement holes  22   a  and  22   b  of tapped member  2  is released to readily remove tapped member  2  which has been mounted on fixing portion  3   a  from fixing portion  3   a.    
     In typical height adjusting mechanisms, the tapped member is provided so as to cover the entire inner wall surface of the through hole in the fixing portion. However, in some cases, including the case of mounting the height adjusting mechanism on light-weight, small-sized electronic devices, it is sufficient that the tapped member can be held by the screw rod by using a small amount of force. In this case, an electronic device can be sufficiently stably supported when the tapped member is provided so as to cover a part of the inner wall surface of the through hole. 
     In such height adjusting mechanisms, such as the height adjusting mechanism described in JP2007-173469A in which the tapped member is fixed only vertically to the fixing portion, when the tapped member is provided so as to cover a part of the inner wall surface of the through hole, the tapped member can easily be removed from the fixing portion because it is not fixed to the fixing portion in the radial direction of the through hole. 
     On the other hand, in height adjusting mechanism  1  according to the embodiment, as discussed above, because tapped member  2  is fixed to fixing portion  3   a,  also in the radial direction of through hole  3   b,  preventing tapped member  2  from being removed from fixing portion  3   a  also becomes possible. On this account, in the height adjusting mechanism according to the embodiment, also in the case of providing the tapped member so as to cover a part of the inner wall surface of the through hole, electronic devices can be stably supported. Accordingly, reducing the size of the tapped member becomes possible, and the entire weight of the electronic device and material and processing costs thus can be reduced. 
     Further, in height adjusting mechanism  1  according to this embodiment, tapped member  2  has engagement holes  22   a,    22   b,  and  22   c  therein, and fixing portion  3   a  has projecting portions  13   a,    13   b,  and  13   c  thereon. However, contrary to this, such a configuration is possible in which the tapped member has projecting portions and the fixing portion has engagement holes therein for engaging the projecting portions with the engagement holes. 
     Furthermore, in height adjusting mechanism  1 , a single tapped member is provided that covers a part of the inner wall surface of the through hole formed in the fixing portion. However, a plurality of tapped members may be provided. Also, a single tapped member that covers the entire inner wall surface of the through hole may be provided. 
     Additionally, the material for forming the tapped member and the screw rod is not restricted to a metal material, which may be a resin material. Because the resin material generally has strength lower than that of the metal material, when the tapped member and the screw rod are made of a resin material, the force of the screw rod that is used to hold the tapped member is smaller than that in the case in which they are made of metal materials. However, the surface of the tapped member on which the thread groove is formed is widened, or a plurality of the tapped members are provided, as necessary, and consequently such configurations can be provided in which the screw rod sufficiently grips the tapped member. Also, the diameter of the screw rod or the thread ridge on the screw rod can be made larger, and a tapped member correspondingly adapted thereto is used to also enhance the strength of the screw rod to grip the tapped member. 
     Second embodiment 
     Next, an electronic device according to a second embodiment of the present invention will be described with reference to  FIG. 6 .  FIG. 6  consists of side views depicting an electronic device according to a second embodiment of the present invention. In this embodiment, a projector, as an exemplary electronic device, is mounted with height adjusting mechanisms  1  according to the first embodiment. Projector  31  has projecting unit  32  on the front part for projecting video, and height adjusting mechanisms  1  at four corners on the bottom surface of housing  3 . 
     In projector  31  shown in  FIG. 6(   a ), the length of support legs  4  of four height adjusting mechanisms  1  extending from the bottom surface of housing  3  is equally varied so as to change the height of projector  31  to reach the surface on which the projector is placed. 
     Further, as shown in  FIG. 6(   b ), not the length of rear support leg  4 , but the length of front support leg  4 , that extend from the bottom surface of housing  3 , is varied to change the projection angle of projector  31 . 
     In addition, projector  31  according to this embodiment has four height adjusting mechanisms  1 . However, in addition to this, a variety of configurations can be provided including such configurations in which two height adjusting mechanisms  1  are provided on the front side and in which one is provided on the rear side and two on the front side.