Abstract:
A tilt foot mechanism includes: two or more tilt feet that allow adjustment of the length of extension with respect to the bottom surface of the case of a projector; two or more locking levers that are each provided corresponding to each of the tilt feet; an elastic part that presses each of the locking levers against a corresponding tilt foot to thus lock the tilt foot; and a control button for causing the two or more locking levers to simultaneously separate from the tilt feet against the pressure of the elastic part.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to a tilt foot mechanism for a projector. 
   2. Description of the Related Art 
   A projector is an image display device of the projection-type for displaying image by projecting image lights on a projection surface such as a screen. Accordingly, obtaining the desired image necessitates adjustment of not only the distance between the projector and the projection surface and the relative positions of the projector and projection surface, but also the angle of the projector. Feet (tilt-feet) having adjustable lengths are thus provided on the bottom surface of the projector case whereby the angle of the projector can be adjusted by modifying the lengths of the tilt feet. This angle adjustment includes both the adjustment of the angle of inclination in the vertical direction and the adjustment of the angle of inclination in the horizontal direction. 
   The arrangement of the above-described tilt feet can take three forms. In the first type of projector, a single tilt foot is provided at the front of the bottom of the case, and two tilt feet are provided at the rear. In this type of projector, the angle of inclination in the vertical direction is adjusted chiefly by means of the front tilt foot, and the angle of inclination in the horizontal direction is adjusted chiefly by means of the two rear tilt feet. In the second type of projector, two tilt feet are provided at the front of the case bottom, and a fixed foot (rear foot) having a fixed, nonadjustable length is provided at the rear. In this type of projector, the angle of inclination in both the vertical and horizontal directions is adjusted by means of the two tilt feet. In the third type of projector, two tilt feet are provided at the front of the bottom of the case, and two tilt feet are also provided at the rear. In this type of projector, the angle of inclination in the vertical and horizontal directions can be adjusted by means of any of the tilt feet. 
     FIGS. 1A and 1B  show one example of a tilt foot of the prior art.  FIG. 1A  shows tilt foot  70  in the locked state, and  FIG. 1B  shows tilt foot  70  in the released state. Tilt foot  70  includes shaft  71  that projects from the bottom surface of the case and foot  72  that contacts the installation surface such as the top surface of a table. Shaft  71  passes through opening  76  of locking lever  75  that can slide back and forth. One end of compressed spring  74  is secured to any point of the case and the other end is secured to locking lever  75 . 
   Accordingly, the restoring force F 1  of spring  74  presses the inner surface (locking surface  77 ) of opening  76  of locking lever  75  against shaft  71 , thereby locking shaft  71  (refer to FIG.  1 A). However, when a control button (not shown) is pressed, a force F 2  in the opposite direction of the restoring force F 1  acts upon locking lever  75  by way of a release mechanism that is not shown in the figure, whereby locking lever  75  slides and locking surface  77  separates from shaft  71  (refer to FIG.  1 B). As a result, the locked state of shaft  71  is released, and the length of the extension of shaft  71  can be adjusted. After the length of the extension of shaft  71  has been adjusted to the desired length, the control button is released, and locking lever  75  automatically returns to its original position, whereby shaft  71  is again locked. 
     FIGS. 2A and 2B  show another example of a tilt foot of the prior art.  FIG. 2A  shows tilt foot  80  in the locked state, and  FIG. 2B  shows tilt foot  80  in the released state. Tilt foot  80  includes shaft  81  that protrudes from the bottom surface of the case and foot  82  that contacts installation surface  83  such as the top surface of a table. Shaft  81  passes through opening  86  of locking lever  85  that can slide back and forth, and projection  87  is formed on the inner surface of opening  86 . Locking lever  85  is rotatably supported by means of axis of rotation  88 , and one end of locking lever  85  is secured to one end of spring  84 . The other end of spring  84  is secured to any position of the case. 
   Accordingly, the restoring force F 1  of spring  84  normally presses projection  87  of locking lever  85  against shaft  81 , thereby locking shaft  81  (refer to FIG.  2 A). However, when a control button (not shown in the figure) is pressed, force F 2  acts upon locking lever  85  by way of a release mechanism (not shown in the figure) such that locking lever  85  rotates around axis of rotation  88  as the fulcrum and projection  87  separates from shaft  81  (refer to FIG.  2 B). As a result, the locked state of shaft  81  is released, and the length of the extension of shaft  81  can be adjusted. After the length of the extension of shaft  81  has been adjusted to the desired length, the control button is released and locking lever  85  automatically returns to its original position, whereby shaft  81  is again locked. 
   As described in the foregoing explanation, one control button was provided for one tilt foot in the prior art. In other words, only one foot could be locked or released through the manipulation of one control button. Accordingly, adjusting the lengths of protrusion of two or more tilt feet necessitated the separate manipulation of two or more control buttons, and operability was extremely poor. 
   SUMMARY OF THE INVENTION 
   It is an object of the present invention: to provide a tilt foot mechanism that can solve the above-described problem of the prior art; and to provide a projector that is provided with such a tilt foot mechanism. 
   The projector tilt foot mechanism of the present invention includes a release mechanism that, through the manipulation of a single control button, causes two or more locking levers that are usually pressing against two or more tilt feet to simultaneously separate from the corresponding tilt feet. 
   In one release mechanism, rotating levers are linked to each of the locking levers. When the control button is pressed, the two or more rotating levers simultaneously rotate, whereby the two or more locking levers that are linked to the rotating levers simultaneously move and separate from the tilt feet. As an example, depressions are formed in each of the locking levers and control button, one end of each of the rotating levers being caught by the depression in a corresponding locking lever, and the other end of each of the rotating levers being caught by the depression in the control button. Alternatively, one end of each of the rotating levers is rotatably linked to a corresponding locking lever by a linking pin, and the other end is rotatably linked to the control button by a linking pin. 
   The restoring force of an elastic part causes each of the locking levers to press against a corresponding tilt foot. The elastic part may directly press a locking lever against the tilt foot, or may indirectly press a locking lever against a tilt foot by way of the control button and a rotating lever. A locking lever can be provided with a locking surface that is pressed against the outer circumference of a tilt foot. Irregularities can be formed on the locking surface, these irregularities meshing with irregularities that are formed on the outer circumference of the tilt foot. The locking surface can also be formed from an elastic material. Forming irregularities on the locking surface or forming the locking surface from an elastic material allows more secure locking of the tilt foot. 
   The above and other objects, features, and advantages of the present invention will become apparent from the following description with reference to the accompanying drawings, which illustrate examples of the present invention. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1A  shows one example of a tilt foot of the prior art with the tilt foot in the locked state. 
       FIG. 1B  shows the released state of the tilt foot shown in FIG.  1 A. 
       FIG. 2A  shows another example of a tilt foot of the prior art with the tilt foot in the locked state. 
       FIG. 2B  shows the released state of the tilt foot shown in FIG.  2 A. 
       FIG. 3A  shows the first embodiment of the projector of the present invention with the tilt foot in the locked state. 
       FIG. 3B  shows the released state of the tilt foot shown in FIG.  3 A. 
       FIG. 4A  shows the use of the tilt feet to adjust the vertical angle of the projector. 
       FIG. 4B  shows the use of the tilt feet to adjust the horizontal tilt angle of the projector. 
       FIG. 5  shows a modification of the projector that is shown in  FIGS. 3A and 3B . 
       FIG. 6  shows a modification of the projector that is shown in  FIGS. 3A and 3B  that differs from the modification shown in FIG.  5 . 
       FIG. 7A  shows the second embodiment of the projector of the present invention with the tilt foot in the locked state. 
       FIG. 7B  shows the released state of the tilt foot shown in FIG.  7 A. 
       FIG. 8A  shows the third embodiment of the projector of the present invention with the tilt foot in the locked state. 
       FIG. 8B  shows the released state of the tilt foot shown in FIG.  8 A. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   As shown in  FIGS. 3A and 3B , projector  100  of the present embodiment includes first tilt foot  10 , second tilt foot  20 , and rear foot  40  (refer to FIG.  4 A). The two tilt feet  10  and  20  are provided on both sides at the front of the bottom surface of case  1  of projector  100 , and rear foot  40  is provided in the center of the rear of the bottom surface.  FIG. 3A  shows the locked state of first tilt foot  10  and second tilt foot  20 , and  FIG. 3B  shows the released state of first tilt foot  10  and second tilt foot  20 . 
   First tilt foot  10  includes shaft  11  that passes in and out of a hole that is provided in the bottom surface of case  1 , and foot  12  that contacts an installation surface such as the top surface of a table. Similarly, second tilt foot  20  includes shaft  21  that passes in and out of another hole that is provided in the bottom surface of case  1 , and foot  22  that contacts an installation surface such as the top surface of a table. 
   Control button  2  is provided between the two shafts  11  and  21 ; and first rotating lever  14 , first locking lever  13 , and first spring  16  are provided between control button  2  and shaft  11 . First rotating lever  14  is rotatably supported by first axis of rotation  15 , and is further provided with a protrusion on each end. One of the protrusions of first rotating lever  14  is caught by the depression of control button  2 , and the other protrusion is caught by the depression of first locking lever  13 . First locking lever  13  is able to slide back and forth in a direction that is orthogonal to the direction of movement of shaft  11  and is ordinarily pressed against the side of shaft  11  under the restoring force F 1  of first spring  16 , which is set in a compressed state. Accordingly, when control button  2  is not being manipulated, locking surface  17  of first locking lever  13  is pressed against the outer surface of shaft  11  by first spring  16 , whereby shaft  11  is locked. A multiplicity of irregularities, (for example thread ridges and thread grooves) is formed on locking surface  17  and on the outer surface of shaft  11 , and intermeshing of the irregularities that are formed on locking surface  17  with the irregularities that are formed on the outer surface of shaft  11  securely locks shaft  11 . 
   Second rotating lever  24 , second locking lever  23 , and second spring  26  are provided between control button  2  and shaft  21 . Second rotating lever  24  is rotatably supported by second axis of rotation  25  and is provided with a protrusion on each end. One of the protrusions of second rotating lever  24  is caught by the depression of control button  2 , and the other protrusion is caught by the depression in second locking lever  23 . Second locking lever  23  is capable of sliding back and forth in a direction that is orthogonal to the direction of movement of shaft  21 , and is ordinarily pressed against the side of shaft  21  by the restoring force F 1  of second spring  26 , which is set in a compressed state. Accordingly, when control button  2  is not being manipulated, second spring  26  presses second locking lever  23  against the side of shaft  21 , whereby locking surface  27  is pressed against the outer surface of shaft  21  and shaft  21  is locked. A multiplicity of irregularities (for example, thread ridges and thread grooves) is formed in locking surface  27  and in the outer surface of shaft  21 , and intermeshing between the irregularities that are formed in locking surface  27  and the irregularities that are formed in the outer surface of shaft  21  securely lock shaft  21 . 
   If male screw threads or female screw threads are formed on the outer surface of shafts  11  and  21 , female screw threads or male screw threads that mesh with the male screw threads or female screw threads formed on the outer surface of shafts  11  and  21  can be formed on the inside surfaces of the holes in the bottom surface of the case through which these shafts  11  and  21  pass, and these screw pitches can then be used to fine-adjust the lengths of extension of shafts  11  and  21 . 
   Instead of forming irregularities on locking surfaces  17  and  27  of looking levers  13  and  23 , locking surfaces  17  and  27  can be formed from an elastic material having great frictional resistance such as rubber, whereby shafts  11  and  21  can be securely locked. 
   In projector  100  of the present embodiment having the above-described construction, when control button  2  is pressed by force F 2  toward the interior of case  1  an inward distance of L 2 , locking levers  13  and  23  slide against the restoring force F 1  of springs  16  and  26  due to the leverage of rotating levers  14  and  24 , and locking surfaces  17  and  27  separate from shafts  11  and  21 . More specifically, when control button  2  is pressed in, one end of each of two rotating levers  14  and  24  that is caught by the depression of control button  2  is lifted up and rotating levers  14  and  24  each rotate with axes of rotation  15  and  25  as fulcrums, as shown in FIG.  3 B. When rotating levers  14  and  24  rotate, the other ends of each of rotating levers  14  and  24  that are caught in the depressions of the two locking levers  13  and  23  move in the direction of mutual approach, and the two locking levers  13  and  23  are thus caused to slide inwardly. As a result, locking surfaces  17  and  27  of locking levers  13  and  23  are separated from the outer surfaces of shafts  11  and  21 , and the locked state is released. 
   With the release of the locked state of the two shafts  11  and  21 , the lengths of first tilt foot  10  and second tilt foot  20  can be adjusted and the angle of projector  100  also adjusted. For example, if first tilt foot  10  and second tilt foot  20  are made shorter as shown in  FIG. 4A , image  200 B that was projected onto area “a” of screen  200  can be shifted downward and projected onto area “b.” Conversely, if first tilt foot  10  and second tilt foot  20  are made longer, image  200 A that was projected onto area “b” of screen  200  can be shifted upward and projected onto area “a.” Alternatively, if first tilt foot  10  is made longer than second tilt foot  20  as shown in  FIG. 4B , image  200 C that was projected onto screen  200  can be tilted as shown by image  200 D. As is obvious from the above-described construction, when first tilt foot  10  and second tilt foot  20  have reached the desired lengths, simply releasing pressure upon control button  2  causes simultaneous locking of first tilt foot  10  and second tilt foot  20 . 
   The present invention as described hereinabove allows the locked state of two or more tilt feet to be simultaneously released through the manipulation of a single control button. In addition, two or more tilt feet that are in the released state can be simultaneously locked through the manipulation of a single control button. 
     FIG. 5  shows a modification of projector  100  that is shown in  FIGS. 3A and 3B . In the projector that is shown in  FIG. 5 , rotating levers  14  and  24  that are shown in  FIGS. 3A and 3B  are modified to rotating levers  14 A and  24 A in which one end is extended in the vertical direction, whereby control button  2  can be arranged in a more interior position of case  1 . As can be clearly understood from  FIG. 5 , the position of control button  2  can be freely altered in the vertical direction by simply modifying the length of one end of each of first rotating lever  14 A and second rotating lever  24 A. 
   In addition, control button  2  and rotating lever  14  that are depicted by solid lines in  FIG. 5  are imaginary components that are depicted to indicate positions of control button  2  and rotating lever  14  that are shown in  FIGS. 3A and 3B . 
     FIG. 6  shows another modification of projector  100  that is shown in  FIGS. 3A and 3B . In the projector that is shown in  FIG. 6 , control button  2  is offset toward tilt foot  20  that is shown in FIG.  3 A and  FIG. 3B  by modifying locking lever  13  that is shown in  FIGS. 3A and 3B  to a longer locking lever  13 B and by modifying locking lever  23  to a shorter locking lever (not shown in FIG.  6 ). Obviously, control button  2  can be offset toward tilt foot  10  if locking lever  23  that is shown in  FIGS. 3A and 3B  is converted to a longer locking lever and locking lever  13  is converted to a shorter locking lever. Further, it will be clear that the control button can be arranged at any position between the two tilt feet by freely setting the length of the two locking lever. 
   In addition, control button  2  and locking lever  13  that are depicted by solid lines in  FIG. 6  are imaginary components that are depicted to indicate positions of control button  2  and locking lever  13  that are shown in  FIGS. 3A and 3B . 
     FIGS. 7A and 7B  show another embodiment of the projector of the present invention.  FIG. 7A  shows a case in which first tilt foot  210  and second tilt foot  220  are locked, and  FIG. 7B  shows a case in which the locked state of first tilt foot  210  and second tilt foot  220  is released. 
   Projector  200  that is shown in  FIGS. 7A and 7B  is advantageous in that the shape of the rotating levers is simple. First rotating lever  214  and second rotating lever  224  that are shown in  FIGS. 7A and 7B  are actually nothing more than thin rectangular plates. 
   One end of first rotating lever  214  is rotatably linked to first locking lever  213  by first linking pin  219 A, and the other end is rotatably linked to control button  202  by second linking pin  219 B. One end of second rotating lever  224  is rotatably linked to second locking lever  223  by third linking pin  229 A, and the other end is rotatably linked to control button  202  by fourth linking pin  229 B. In other words, first rotating lever  214  is rotatably linked to first locking lever  213  and control button  202 , and second rotating lever  224  is rotatably linked to second locking lever  223  and control button  202 . Accordingly, as shown in  FIG. 7B , when control button  202  is pushed upward, first locking lever  213  and second locking lever  223  move similarly to first locking lever  13  and second locking lever  23  that are shown in  FIG. 3B , and the locked state of the two tilt feet  210  and  220  is released simultaneously. 
   First rotating lever  214  and second rotating lever  224  that are shown in  FIGS. 7A and 7B  can also be constituted by flexible wires. Forming first rotating lever  214  and second rotating lever  224  by wires enables a reduction of the weight of projector  200 . When first rotating lever  214  is formed from wire, one end of the wire is wound around first linking pin  219 A and the other end is wound around second linking pin  219 B. Further, when second rotating lever  224  is formed from wire, one end of the wire is wound around third linking pin  229 A and the other end is wound around fourth linking pin  229 B. Alternatively, one end of the wire can be secured directly to locking lever and control button, whereby the first to fourth linking pins can be omitted. 
     FIGS. 8A and 8B  show a modification of projector  200  that is shown in  FIGS. 7A and 7B .  FIG. 8A  shows first tilt foot  210  and second tilt foot  220  in the locked state, and  FIG. 8B  shows first tilt foot  210  and second tilt foot  220  when the locked state is released. Of the components of projector  200  that are shown in  FIGS. 8A and 8B , components that are identical to those of projector  200  shown in  FIGS. 7A and 7B  are given the same reference numerals, and redundant explanation is here omitted. 
   Projector  200  that is shown in  FIGS. 8A and 8B  has the advantage of reducing the number of springs for pressing the locking levers against the shafts. Specifically, only one spring is used in projector  200  that is shown in  FIGS. 8A and 8B . 
   Projector  200  that is shown in  FIGS. 8A and 8B  is provided with third spring  236  in place of first spring  216  and second spring  226  that are shown in  FIGS. 7A and 7B . Third spring  236  is arranged inside case  1  in a compressed state, one end being secured to any point of case  1 , and the other end being secured to the rear surface of control button  202 . Control button  202  is therefore ordinarily subjected to downward pressure under the restoring force F 1  of third spring  236 , whereby first locking lever  213  is ordinarily pressed by way of first rotating lever  214  against the side of shaft  211 . Similarly, second locking lever  223  is ordinarily pressed by way of second rotating lever  224  against the side of shaft  221 . As a result, when control button  202  is not being manipulated, the restoring force F 1  of third spring  236  causes locking surface  217  of first locking lever  213  to be pressed against the outer surface of shaft  211  and locking surface  227  of second locking lever  223  to be pressed against the outer surface of shaft  221 , whereby shafts  211  and  221  are locked. 
   However, as shown in  FIG. 8B , when control button  202  is lifted upward, first rotating lever  214  and second rotating lever  224  move similarly to the first rotating lever  214  and second rotating lever  224  shown in  FIG. 7B , and the locked state of shafts  211  and  221  is simultaneously released. 
   The shafts, feet, locking levers, rotating levers, and control button that have been described thus far are fabricated from resin or metal. Alternatively, the shafts, feet, locking levers, rotating levers, and control button can also be fabricated by a die-casting method. 
   While preferred embodiments of the present invention have been described using specific terms, such description is for illustrative purposes only, and it is to be understood that changes and variations may be made without departing from the spirit or scope of the following claims.