Abstract:
An adjustable hanging device for securing an electronic device and being capable of angular adjustment is provided. One control screw is disposed for the operation along one dimension. When the adjustable hanging device is used for multi-dimensional angular adjustments, the control screws are disposed to extend to one operational side. Due to the mechanical integration and the compact design of the adjustable hanging device, the advantages of volume reduction and simpler manipulation at one operational side would be expectable.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an adjustable hanging device and, more particularly, to a device for hanging an electronic device where the hanging angles are adjustable. 
     2. Description of Related Art 
     As technologies continue advancing, electronic devices such as displays, speakers, projectors and monitors have become common and adapted to fulfil various purposes and conditions in our daily lives. Such electronic devices usually need to be hung or attached while operating. They are generally placed on the ground with stands, attached to the wall with mounting structures, or hung on the ceiling with hanging devices. In many cases, suspending such electronic devices with hanging devices is deemed to be a favorable option for utilizing space effectively and avoiding blocking visions of viewers. 
     It may be assumed that an electronic device does not need to be moved frequently if it is hung on the ceiling. For example, a projector is often hung on the ceiling in a meeting room with a fixed projection screen. Speakers and video recorders are commonly hung in an auditorium. However, minor adjustments are still required although such electronic devices are generally fixed in positions. For example, a projector might require minor adjustments in leveling, height or angles. 
     Existing hanging devices already disclose concepts and structures that may be adjusted in at least a position or angle. For example, a hanging device may be moved or rotated in three dimensions using three controlling screw rods and relevant mechanisms. However, within known controlling mechanisms and adjusting structures, the controlling ends (i.e. operable ends of the screw rods) are usually disposed on different sides of a hanging device due to limitations in structural design. 
     The space where a hanging device is disposed is defined with X-axis, Y-axis and Z-axis, wherein X-axis and Y-axis are perpendicular to each other and define a horizontal plane, and Z-axis is perpendicular to X-axis and Y-axis. The controlling ends of an existing hanging device extend in different directions, such as having a first controlling screw rod on the left side of the hanging device to rotate the hanging device around Z-axis, having a second controlling screw rod on the front side of the hanging device to rotate the hanging device around Y-axis, and having a third controlling screw rod at the bottom of the hanging device to rotate the hanging device around X-axis, thus to prevent different controlling and adjusting mechanisms of respective dimensions from interfering one another. 
     It is not easy for an user or technician to operate an electronic device hung on the ceiling, and it is even more difficult and complicated when controlling ends are disposed in different positions on the hanging device. 
     Therefore, it is desirable to provide a hanging device for electronic devices that allows users to easily adjust its positions and angles with ease. 
     SUMMARY OF THE INVENTION 
     The object of the present invention is to provide a hanging device that is not only used to attach an electronic device firmly, but also adjustable in positions and angles with ease. 
     To achieve the object, the structural design of the present invention includes a controlling screw rod corresponding to the adjusting requirement in a dimension. In a preferred embodiment, independent adjustments in three dimensions may be achieved through three controlling screw rods. 
     Another object of the present invention is to allow users to operate on the same side and adjust angles of the hanging device in different dimensions without interference one another&#39;s mechanism. In other words, unique structural design of the present invention overcomes shortfalls of interference between mechanisms in prior art. Mechanisms of each dimension are skillfully integrated to allow users to operate all controlling screw rods on the same side. As a result, both the size and the space required for operating the hanging device of present invention are smaller. 
     In order to achieve these objects, the present invention provides an adjustable hanging device including a bearing base, a dome member and a first adjusting module. The dome member includes two first inner flat surfaces oppositely facing each other and a first inner cambered surface connecting the two first inner flat surfaces. The first adjusting module includes a first sliding member, a first gear, a first screw rod and a first adjusting column. The first sliding member has two second outer flat surfaces oppositely facing away from each other and a second outer cambered surface connecting the two second outer flat surfaces. When the first sliding member is fitted in the dome member, the second outer cambered surface corresponds to the first inner cambered surface, and the second outer flat surfaces correspond to the first inner surfaces. The first gear is disposed concentrically on the bearing base and the first sliding member. The first gear has two wings, each of the wings respectively has a first curved groove, and one of the first curved grooves has a plurality of teeth. Each of the curved grooves has a first end and a second end. A first radius of curvature, defined by a straight line between a center of the first gear and the first end, is smaller than a second radius of curvature, defined by a straight line between the center of the first gear and the second end. The first screw rod engages with the teeth of the first gear. The first adjusting column is connected to the first sliding member and elongates through the first curved groove. While the first gear is driven by the first screw rod to rotate around a center, the first adjusting column and the first gear are capable of moving relatively due to the first adjusting column being restricted within the first curved groove, and further the second outer cambered surface is capable of relatively sliding with respect to the first inner cambered surface due to the restriction between the first inner flat surfaces and the second outer flat surfaces, so as drive the first sliding member relatively sliding with respect to the bearing base. 
     Other objects, advantages, and novel features of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of the adjustable hanging device of present invention; 
         FIGS. 2A and 2B  are perspective exploded views in different angles of the adjustable hanging device; 
         FIG. 3  is a perspective view of part of the adjustable hanging device, wherein the second sliding member is fitted in the first sliding member, and the first sliding member is disposed in the bearing base; 
         FIG. 4  is a perspective view of part of the adjustable hanging device, wherein the first gear and the first screw rod are disposed in the first housing; 
         FIG. 5A  is a top view of part of the adjustable hanging device; 
         FIG. 5B  is a side view of the adjustable hanging device corresponding to  FIG. 5A ; 
         FIG. 5C  is a top view of the first adjusting module of the adjustable hanging device in action; 
         FIG. 5D  is a side view of the adjustable hanging device in action corresponding to  FIG. 5C ; 
         FIG. 5E  is another top view of the first adjusting module of the adjustable hanging device in action; 
         FIG. 5F  is another side view of the adjustable hanging device in action corresponding to  FIG. 5E ; 
         FIG. 5G  is a schematic illustration of the first adjusting columns of  FIGS. 5A and 5C  relatively moving with respect to the first curved grooves of the first gear; 
         FIG. 5H  is another schematic illustration of the first adjusting columns of  FIGS. 5A and 5E  relatively moving with respect to the first curved grooves of the first gear; 
         FIG. 6  is a perspective view of the adjustable hanging device wherein the second gear and the second screw rod are disposed in the first housing; 
         FIG. 7A  is another top view of part of the adjustable hanging device; 
         FIG. 7B  is a side view of part of the adjustable hanging device corresponding to  FIG. 7A ; 
         FIG. 7C  is a top view of the second adjusting module of the adjustable hanging device in action; 
         FIG. 7D  is a side view of the second adjusting module in action corresponding to  FIG. 7C ; 
         FIG. 7E  is another top view of the second adjusting module of the adjustable hanging device in action; 
         FIG. 7F  is another side view of the second adjusting module in action corresponding to  FIG. 7E ; 
         FIG. 8  is a perspective view illustration of the third adjusting module disposed on the second housing of the adjustable hanging device; 
         FIG. 9A  is a top view of part of the adjustable hanging device; 
         FIG. 9B  is a top view of the third adjusting module of the hanging device in action; 
         FIG. 9C  is another top view of the third adjusting module of the hanging device in action; 
         FIG. 10  is a perspective view of the bracket of the adjustable hanging device; 
         FIG. 11  is a schematic illustration of the corresponding bracket and bearing base. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     With reference to  FIG. 1 , a perspective view of an adjustable hanging device of the present invention is shown. The adjustable hanging device comprises a bearing base  1 , a first adjusting module  2 , a second adjusting module  3 , a third adjusting module  4  and a bracket  6 . The bracket  6  is suitable to be attached to an electronic device such as a projector. Through relative movements of the first adjusting module  2 , the second adjusting module  3 , and the third adjusting module  4  in respect of the bearing base  1 , the electronic device is also relatively adjusted to the bearing base  1 . The electronic device may be adjusted in X-axis, Y-axis or Z-axis independently to achieve a best angle position. 
     First, detail structures of and operating relationship between the bearing base  1  and the first adjusting module  2  are disclosed. Referring to  FIGS. 2A and 2B , perspective exploded views in different angles of the adjustable hanging device of the present invention, with X-axis adjustment and relevant parts, are shown. The bearing base  1  includes a dome member  10 . The dome member  10  has two first inner flat surfaces  101   a  oppositely facing each other and a first inner cambered surface  101   b  connecting the two first flat surfaces  101   a . A center point  1011  is defined within the bearing base  1 . 
     Referring to  FIGS. 2A, 2B and 4 , the first adjusting module  2  in this embodiment includes a first sliding member  21 , a first gear  22 , a first screw rod  23 , two first adjusting columns  24  and a first shaft  25 . It should be noted that the number of the first adjusting columns  24  may be adjusted in other embodiments of the present invention. For example, if first adjusting module  2  has only one first adjusting column  24 , the function of the adjusting column  24  still remains. 
     Referring to  FIGS. 2A and 2B , the first sliding member  21  is shaped approximately to a dome corresponding to the dome member  10 , and has two second outer flat surfaces  210   a  oppositely facing away from each other and a second outer cambered surface  210   b  connecting the two outer flat surfaces  210   a . The first shaft  25  includes two shaft bodies  251  separately inserted on the external of the first sliding member  21 . The two first adjusting columns  24  are respectively connected to the first sliding member  21  and near the shaft bodies  251 . In the embodiment, the shaft bodies  251  are perpendicular to the first adjusting columns  24 , but not limited thereof. 
     Referring to  FIGS. 2A, 2B and 3 ,  FIG. 3  illustrates the first sliding member  21  being disposed in the bearing base  1 . When the first sliding member  21  is fitted in the dome member  10  of the bearing base  1 , the second outer cambered surface  210   b  corresponds to the first inner cambered surface  101   b , and the second outer flat surfaces  210   a  correspond to the first inner flat surfaces  101   a.    
     As shown in  FIG. 4 , the bearing base  1  of the adjustable hanging device includes a first housing  11  simultaneously enclosing the dome member  10  and the first sliding member  21 . The first housing  11  has a plurality of first holes  11   a  and the first adjusting columns  24  penetrate therethrough. Practically, the first holes  11   a , for the first adjusting columns  24  penetrating therethrough, are perpendicular to the first screw rod  23 . In other words, the first holes  11   a  extends perpendicularly to the extending direction of the first screw rod  23 , and the shaft bodies  251  of the first shaft  25  partially protrude through the side walls of the first housing  11 . 
       FIG. 4  further illustrates the assembly of the first gear  22 , the first screw rod  23 , the first sliding member  21  and the first housing  11 . The first gear  22  is disposed on the first housing  11  and concentrically fitted to the bearing base  1  and the first sliding member  21 . The first gear  22  has two wings  22   a , each of the wings  22   a  respectively has a first curved groove  220 , and one of the wings  22   a  has a plurality of teeth  22   b . Each of the first adjusting columns  24  respectively elongates through one of the first curved groove  220 . The first screw rod  23  engages with the teeth  22   b  of the first gear  22 . 
     It should be noted that the first housing  11  may be removed in other embodiments of the present invention. The first gear  22  may be disposed directly on the first sliding member  21 . Furthermore, in other embodiments of the present invention, the number of the curved grooves  220  may be adjusted according to the number of the first adjusting columns  24 . For example, if the first adjusting module  2  only has one first adjusting column  24 , there would be only one first curved groove  220  accordingly. 
       FIG. 5A , a top view of part of the adjustable hanging device, and  FIG. 5B , a side view of the adjustable hanging device corresponding to  FIG. 5A , illustrate the interactions between various parts. Referring to  FIG. 5A , X-axis and Y-axis are perpendicular and cross each other on the center  221  of the first gear  22 , and X-axis extends through the first shaft  25 . Therefore  FIG. 5A  is a top view of X-Y plane illustrating a status when the first adjusting module  2  and the dome member  10  are not having any interaction. 
     Referring to  FIG. 5B , Z-axis extends through the center point  1011  of the bearing base  1  and is perpendicular to the bearing base  1 . X-axis extends through the first shaft  25  and is parallel to the bearing base  1 . Therefore  FIG. 5B  is a side view of X-Z plane illustrating the first shaft  25 , X-axis and the bearing base  1  are perpendicular to Z-axis when the first sliding member  21  and the dome member  10  are not having any interaction. It should be noted that X-axis, Y-axis and Z-axis do not have to be perpendicular to one another. They can be approximately perpendicular. 
     In the embodiment, as shown in  FIG. 5A , the two first curved grooves  220  are disposed symmetrically with respect to Y-axis in the wings  22   a  of the first gear  22 . Each of the first curved grooves  220  has a first end  2201  and a second end  2202 . A first radius of curvature R 1 , defined by a straight line between the center  221  of the first gear  22  and the first end  2201 , is smaller than a second radius of curvature R 2 , defined by a straight line between the center  221  of the first gear  22  and the second end  2202 . In other words, a radius of curvature increases as it gets closer to the second end  2202  of either of the first curved grooves  220 . 
       FIG. 5C  is a top view illustrating the first sliding member  21  relatively slides with respect to the bearing base  1  when the first screw rod  23  is driving the first gear  22 .  FIG. 5D  is a side view illustration corresponding to  FIG. 5C .  FIG. 5E  is another top view illustrating the first sliding member  21  relatively slides with respect to the bearing base  1  when the first screw rod  23  is driving the first gear  22 .  FIG. 5F  is a side view illustration corresponding to  FIG. 5E . 
       FIG. 5G  is a schematic illustration of the first adjusting columns  24  of  FIGS. 5A and 5C  relatively moving with respect to the first curved grooves  220  of the first gear  22 .  FIG. 5H  is a schematic illustration of the first adjusting columns  24  of  FIGS. 5A and 5E  relatively moving with respect to the first curved grooves  220  of the first gear  22 . 
     Through the arrangement of various parts mentioned above, the first screw rod  23  drives the first gear  22  to rotate around the center  221 . As compared to the first gear  22  in  FIG. 5A , the first gear  22  in  FIG. 5C  rotates clockwise around the center  221 . The first adjusting columns  24  are restricted within the first curved grooves  220  and slides relatively in respect of the first gear  22 . In other words, the inner surface of the first curved grooves  220  push the first adjusting columns  24  to slide within the first curved grooves  220  when the first gear  22  is rotating. 
     While the first adjusting columns  24  are sliding, as shown in  FIG. 5G , each of the adjusting columns  24  moves from the center to the left (dot lines). One of the adjusting columns  24  (the first adjusting column  24  on the right hand side) is positioned in the second end  2202  of one of the first curved grooves  220 , and another one of the first adjusting columns  24  (the first adjusting column  24  on the left hand side) is positioned in the first end  2201  of another one of the first curved grooves. At the same time, the second outer cambered surface  210   b  relatively slides in respect of the first inner cambered surface  101   b  due to the restrictions of the first inner flat surfaces  101   a  and the second outer flat surfaces  210   a , so as to drive the first sliding member  21  relatively sliding with respect to the bearing base  1 . Therefore, the first shaft  25  is driven to deviate from X-axis and relatively tilts at a first angle θ 1  in respect of X-axis and the bearing base  1  from the side view of X-Z plane. 
     When the first screw rod  23  drives the first gear  22  to rotate anti-clockwise around the center  221  in  FIG. 5E , each of the adjusting columns  24  moves from the center to the right in  FIG. 5H , and one of the adjusting columns  24  (the first adjusting column  24  on the right hand side) is positioned in the first end  2201  of one of the first curved grooves  220 , and another one of the first adjusting columns  24  (the first adjusting column  24  on the left hand side) is positioned in the second end  2202  of another one of the first curved grooves. At the same time, the second outer cambered surface  210   b  relatively slides in respect of the first inner cambered surface  101   b  due to the restrictions of the first inner flat surfaces  101   a  and the second outer flat surface  210   a , so as to drive the first sliding member  21  relatively sliding with respect to the bearing base  1 . From the side view of X-Z plane, the first shaft  25  is driven to deviate from X-axis and relatively tilts at a first angle θ 1  in respect of X-axis and the bearing base  1 . In the embodiment, the first angle θ 1  is preferably between −5 and 5 degrees. However, the adjustable range of the first angle θ 1  may vary and does not have any specific limitation in other embodiments of the present invention. 
     And now, Y-axis adjustment and relevant parts will be discussed to disclose detailed structures of the second adjusting module  3 . With reference to  FIGS. 2A, 2B, 3 and 6 , the second adjusting module  3  includes a second sliding member  31 , a second gear  32 , a second screw rod  33 , two second adjusting columns  34  and a second shaft  35 . Also, it should be noted that the number of the second adjusting columns  34  may be adjusted in other embodiments of the present invention. 
     With reference to  FIGS. 2A and 2B , the second sliding member  31  has two third outer flat surfaces  310   a  oppositely facing away from each other and a third outer cambered surface  310   b  connecting the third outer flat surfaces  310   a . The second shaft  35  has two shaft bodies  351  separately inserted on the external of the second sliding member  31 . The two second adjusting columns  34  are respectively connected to the second sliding member  31  and near to the shaft bodies  351 . In the embodiment, the shaft bodies  351  are perpendicular to the second adjusting columns  34 , but not limited thereof. 
       FIG. 3  illustrates the second sliding member  31  fitting in the first sliding member  21 . As shown in  FIGS. 2A and 3 , the first sliding member  21  has two second inner flat surfaces  211   a  oppositely facing each other and a second inner cambered surface  211   b  connecting the two second inner flat surfaces  211   a . When the second sliding member  31  is fitted in the first sliding member  21 , the second inner cambered surface  211   b  corresponds to the third outer cambered surface  310   b , and each of the second inner flat surfaces  211   a  respectively corresponds to one of the third outer surfaces  310   a . The second adjusting columns  34  are connected to the second sliding members  31 . Similarly in the embodiment of the adjustable hanging device of the present invention shown in  FIG. 4 , the first housing  11  simultaneously encloses bearing base  1 , the first sliding member  21  and the second sliding member  31 , and allows the first adjusting columns  24  and the second adjusting columns  34  penetrate through the first holes  11   a . In the embodiment, as shown in  FIG. 6 , the first holes  11   a  penetrated by the second adjusting columns  34  are parallel to the second screw rod  33 . In other words, the first holes  11   a  penetrated by the second adjusting columns  34  and the first screw rod  23  extend in the same direction. 
       FIG. 6  illustrates the second gear  32  and the second screw rod  33  fitting in the first housing  11 . When the first gear  22  is fitted in the first housing  11  as shown in  FIG. 4 , the second gear  32  may be concentrically disposed on the first gear  22  as shown in  FIG. 6 . The second gear  32  has two wings  32   a , each of the wings  32   a  has a second curved groove  320 , and one of the wings  32   a  has a plurality of teeth  32   b . The second adjusting columns  34  elongate through the second curved grooves  320 . The second screw rod  33  engages with the teeth  32   b  of the second gear  32 . It should be noted that the number of curved grooves  320  may be adjusted according to the number of the second adjusting columns  34  in other embodiments of the present invention. For example, if the second adjusting module  3  only has a second adjusting column  34 , there is only one second curved groove  320  in correspondence to one second adjusting column  34 . 
       FIG. 7A  is a top view of part of the adjustable hanging device, and  FIG. 7B  is a side view corresponding to  FIG. 7A . In  FIG. 7A , in order to explain the interactions between various parts, it is assumed that X-axis and Y-axis are perpendicular to each other and cross on the center  321  of the second gear  32 . Y-axis extends through the second shaft  35  and X-axis extends through the first shaft  25 . Therefore,  FIG. 7A  is a top view of X-Y plane illustrating a status when the second sliding member  31  and the bearing base  1  are not having any interactions. In  FIG. 7B , it is assumed that Z-axis extends through the center point  1011  of the bearing base  1  and is perpendicular to the bearing base  1 . Y-axis extends through the second shaft  35  and is parallel to the bearing base  1 . Therefore,  FIG. 7B  is a side view of Y-Z plane illustrating the second sliding member  31  and the bearing base  1  are not having any interactions. The second shaft  35 , Y-axis and the bearing base  1  are perpendicular to Z-axis. 
     In the embodiment, as shown in  FIG. 7A , the two second curved grooves  320  are disposed symmetrically with respect to X-axis in the wings  32   a  of the second gear  32 . Each of the second curved grooves  320  has a third end  3201  and a fourth end  3202 . A third radius of curvature R 3 , defined by a straight line between the center  321  of the second gear  32  and the third end  3201 , is smaller than a fourth radius of curvature R 4 , defined by a straight line between the center  321  of the second gear  32  and the fourth end  3202 . In other words, a radius of curvature increases as it gets closer to the fourth end  3202  of either of the second curved grooves  320 . 
       FIG. 7C  is a top view illustrating the second sliding member  31  relatively slides with respect to the bearing base  1  when the second screw rod  33  is driving the second gear  32 .  FIG. 7D  is a side view illustration corresponding to  FIG. 7C .  FIG. 7E  is another top view illustrating the second sliding member  31  relatively slides with respect to the bearing base  1  when the second screw rod  33  is driving the second gear  32 .  FIG. 7F  is a side view illustration corresponding to  FIG. 7E . 
     Through the arrangement of various parts are discussed above and similar to the adjustment principle in X-axis, the second screw rod  33  drives the second gear  32  to rotate anti-clockwise around the center  321 . The inner surface of the second curved groove  320  pushes the second adjusting columns  34  to slide within the second curved groove  320 . Due to the restrictions of the second inner flat surfaces  211   a  and third outer flat surfaces  310   a , the third outer cambered surface  310   b  relatively slides in respect of the second inner cambered surface  211   b , so that the second sliding member  31  relatively slides in respect of the bearing base  1 . In the view of Y-Z plane, the second sliding member  31  relatively sliding in respect of the bearing base  1  causes the second shaft  35  to deviate from Y-axis and tilt in the second angle θ 2  in respect of the bearing base  1  and Y-axis. 
     In a contrary,  FIG. 7E  illustrates the second gear  32  rotating clockwise around the center  321  in the same movements disclosed earlier. In the view of Y-Z plane, the second shaft  35  is driven to deviate from Y-axis and tilt to the second angle θ 2  in respect of the bearing base  1  and Y-axis. In the embodiment, the second angle θ 2  is preferably between −5 and 5 degrees, but not limited thereto. 
     With reference to  FIGS. 2A, 2B and 3 , the bearing base  1  is formed with a first fixing hole  101  on the dome member  10 . The first sliding member  21  is formed with a first through hole  212 . The second sliding member  31  is formed with a second through hole  311 . A first screw  71  penetrates through the first through hole  212  and second through hole  311  to screw with the first fixing hole  101 . To avoid interference from the first screw  71  while the first sliding member  21  and the second sliding member  311  are sliding, the diameters of the first through hole  212  and second through hole  311  are larger than the diameter of the first screw  71 . 
       FIG. 10  is a schematic illustration of the bracket  6 . The bracket  6  includes a plurality of first bending portions  61  and a plurality of second bending portions  62 . Each of the first bending portions  61  has a second hole  61   a , as shown in  FIG. 6 , for accommodating ends of the first shaft  25  and the second shaft  35 . A plurality of second screws  72  are respectively fastened on the first shaft  25  and the second shaft  35 . 
       FIG. 11  is a schematic illustration of the corresponding bracket  6  and bearing base  1 . The bracket  6  has a third hole  62   a , and the dome member  10  of the bearing base  1  is disposed in the third hole  62   a . The second bending portions  62  of the bracket  6  may be attached to an electronic device (not shown). As shown in  FIGS. 5A to 5E and 7A to 7E , the bracket  6  moves together with the first shaft  25  in respective of the bearing base  1  when the first sliding member  21  is relatively sliding in respect of the bearing base  1 . The bracket  6  moves together with the second shaft  35  in respect of the bearing base  1  when the second sliding member  31  is relatively sliding in respect of the bearing base  1 . So that the electronic device attached to the bracket  6  relatively moves in respect of the bearing base  1 . 
     It should be noted that the third hole  62   a  of the bracket  6  is slightly larger than the diameter of the dome member  10  of the bearing base  1 , the second screws  72  are fastened on the first shaft  25  and second shaft  35  with a gap from their respective first bending portions  61 , and the diameters of the second holes  61   a  are larger than the diameters of the first shaft  25  and second shaft  35 , so that the bracket  6  is not over tightly attached to the first shaft  25  and second shaft  35 . Therefore, the first shaft  25  and second shaft  35  may freely rotate in respect of corresponding second holes  61   a . It will prevent the bracket  6  from being overly restricted or even locked while rotating on X-Z plane or Y-Z plane, or being unable to move in respect of the bearing base  1  because the third hole  62   a  is stuck with the dome member  10  of the bearing base  1 . 
     Referring to  FIGS. 4, 6 and 8 , wherein  FIG. 8  is schematic illustration of the partly assembly of the adjustable hanging device of the present invention. A plurality of third screws  73  respectively are screwed with the center through hole of the first gear  22 , the center through hole of the second gear  32 , the center through hole of the first housing  11  and the center through hole of the second housing  12 , so that they are connected to each other. Therefore, the center of the second housing  12  and the center point  1011  of the bearing base  1 , viewed from X-Y plane, are in the same position. 
     Lastly, Z-axis adjustment and relevant parts are discussed herefrom. With reference to  FIG. 8 , the bearing base  1  includes the second housing  12  enclosing the first adjusting module  2  and the second adjusting module  3 , is connected to the first housing  11 , and allows the first screw rod  23 , the second screw rod  33 , the first shaft  25  and the second shaft  35  to partly reveal. The third adjusting module  4  is disposed on the second housing  12  and fitted to the first adjusting module  2  and the second adjusting module  3 . The third adjusting module  4  includes a third screw rod  41 , a sliding block  42  and a third adjusting column  43 . The sliding block  42  has a thread portion  42   a  and a sliding groove  42   b . The thread portion  42   a  engages with the third screw rod  41 . The third adjusting column  43  is disposed on the second housing  12  and penetrates through the sliding groove  42   b , and thus drives the first adjusting module  2  and the second adjusting module  3 . More details will be discussed further. It should be noted that the sliding groove  42   b  penetrated by the third adjusting column  43  is perpendicular to the third screw rod  41 . In other words, the sliding groove  42   b , penetrated by the third adjusting column  43 , extends in a direction perpendicular to a extending direction of the third screw rod  41 . 
     Movements of the third adjusting module  4  are disclosed in more details herefrom.  FIG. 9A  is a top view of part of the adjustable hanging device. It is also assumed that X-axis is perpendicular to Y-axis, X-axis extends through the first shaft  25 , Y-axis extends through the second shaft  35 , and X-axis and Y-axis cross on the center of the second housing  12  (same as the center point  1011  of the bearing base  1 ). Hence  FIG. 9A  is a top view of X-Y plane illustrating a status when the third adjusting module  4  is not interacting with the bearing base  1 , the first adjusting module  2  and the second adjusting module  3 . The second housing  12  has the center which is the same as the center point  1011  of the bearing base  1 . The center point  1011  of the bearing base  1  may define a first circumference (A), and the third adjusting column  43  is on the first circumference (A). The center point  1011  of the bearing base  1  is aligned with the third adjusting column  43  on X-axis. 
       FIG. 9B  is a top view illustrating the first adjusting module  2  and the second adjusting module  3  rotate around the center point  1011  of the bearing base  1  when the third screw rod  41  is driving sliding block  42 .  FIG. 9C  is another top view illustrating a different rotating direction. When the third screw rod  41  is driving sliding block  42 , as shown in  FIG. 9B , the third adjusting column  43  not only relatively slides in the sliding groove  42   b , but also rotates anti-clockwise around the center point  1011 , so that the straight line between the third adjusting column  43  and the center point  1011  deviates from X-axis. Contrarily, as shown in  FIG. 9C , the third adjusting column  43  rotates clockwise around the center point  1011 . The third adjusting column  43  relatively rotates around the center point  1011 , drives the second housing  12  and the first housing  11  connected to the second housing  12  to rotate, and simultaneously drives the first adjusting module  2  and second adjusting module  3  enclosed in the first housing  11  and the second housing  12  to relatively rotate around the center point  1011  of the bearing base  1 . Since the bracket  6  is connected to the first shaft  25  and the second shaft  35 , the bracket  6  also rotates with the first adjusting module  2  and the second adjusting module  3 . With reference to  FIGS. 9B and 9C , the first shaft  25  and the second shaft  35  respectively and simultaneously deviate from X-axis and Y-axis, so that the first shaft  25  and the second shaft  35  simultaneously rotate clockwise or anti-clockwise on the X-Y plane. Therefore, when the first shaft  25  relatively rotates around the center point  1011  of the bearing base  1 , a third angle θ 3  is formed between X-axis and the straight line between the third adjusting column  43  and the center point  1011 . The third angle θ 3  is preferably between −5 and 5 degrees, but not limited thereto. 
     Through the arrangement of the three adjusting modules discussed above, the first screw rod  23 , the second screw rod  33  and the third screw rod  41  extend on the same operating side to the ease of an user. 
     Finally, as illustrated in  FIG. 1 , the adjustable hanging device may have a third housing  51  enclosing the third adjusting module  4  and allow the third screw rod  41  to partly reveal. The third housing  51  may be screwed with the third screw  73 . The third housing  51  may be connected to a fixing bracket that may be hung onto the ceiling. 
     In conclusion, it may be achieved to have the first screw rod, the second screw rod and the third screw rod on the same operating side through the structures of the first adjusting module, the second adjusting module and the third adjusting module mentioned above. A user may operate three screw rods to adjust positions of the electronic device in different dimensions with ease on the same side. The operation convenience is greatly improved. 
     Although the present invention has been explained in relation to its preferred embodiment, it is to be understood that many other possible modifications and variations can be made without departing from the spirit and scope of the invention as hereinafter claimed.