Abstract:
The present invention provides a pointing stick device for use with a computer. The pointing stick device has a base plate having an aperture, a stick having a lower portion, at least one strain gauge attached on the lower portion, and a binding compound filling the space between the lower portion of the stick and the aperture of the base plate. The lower portion of the stick is tapered. The binding compound covers the strain gauges and fixes the lower portion of the stick vertically in the aperture of the base plate. When the stick is vertically depressed, the strain gauge installed on the lower portion of the stick senses the vertical downward pressure from reaction forces transmitted through the binding compound and generates the corresponding sensing signals.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a pointing stick device, and more particularly, to a pointing stick device with increased sensitivity in the vertical direction. 
     2. Description of the Prior Art 
     Pointing devices, such as keyboards, mice, joysticks and remote control devices, are widely used computer peripherals for controlling the movement, position and function of a cursor on a computer screen. The prior art pointing device can only control the two-dimensional movement of the cursor. This means that, after moving the cursor to the desired position, another button must be clicked to execute the desired function. Moreover, as 3-D pictures and 3-D animations become more widespread, a pointing device that can generate three-dimensional, rather than two-dimensional, signals will prove more convenient for users when controlling movements in a 3-D space. 
     Please refer to FIG.  1 . FIG. 1 is a cross-sectional diagram of a prior art pointing stick device  10 . The prior art pointing stick device  10  comprises a column-shaped stick  12  for controlling the two-dimensional movements of a cursor (not shown) on a computer screen. The stick  12  has an upper portion  13  and a lower portion  15 . The pointing stick device  10  further comprises a base plate  20  having an aperture  21  for fixing the stick  12 , a plurality of strain gauges  14  vertically installed on the lower portion  15  of the stick  12 , and a binding compound  22  filling the space between the lower portion  15  of the stick  12  and the aperture  21  of the base plate  20 . The strain gauges  14  sense pressure and generate corresponding sensing signals. The binding compound  22  fixes the lower portion  15  of the stick  12  vertically into the aperture  21  of the base plate  20 . 
     Please refer to FIG.  2 . FIG. 2 is a cross-sectional diagram of another prior art pointing stick device  30 . The main difference between the pointing stick device  30  and the pointing stick device  10  is that the pointing device  30  has a cover ring  26  installed on the periphery of the binding compound  22 . When the stick is bent by a horizontal force, the cover ring  26  will help generate the reaction forces that squeeze the plurality of strain gauges  14  installed on the stick  12 , and thereby cause the strain gauges  14  to generate the corresponding signals. 
     Please refer to FIG.  3  and FIG.  4 . FIG. 3 is a cross-sectional diagram of the pointing stick device  10  or  30  shown in FIG. 1 or FIG. 2 with a horizontal force acting on the stick  12 . The central line shown in FIG. 3 represents the bending direction of the stick  12  with the horizontal force. The bending of the stick  12  caused by the horizontal force will make the strain gauge  14  generate bending strain signals S x1 , S y1 . FIG. 4 is a cross-sectional diagram of the pointing stick device  10  or  30  shown in FIG. 1 or FIG. 2 with a vertical force acting on the stick  12 . The central line shown in FIG. 4 represents the direction of compression of the stick  12  with the vertical force. The compression of the stick  12  caused by the vertical force will make the strain gauge  14  generate compressive strain signals S z1 ) When a force is applied to the pointing stick device  10 ,  30 , the base plate  20  and the binding compound  22  will squeeze the strain gauges which then generate the strain signals S x1 , S y1 , and S z1.    
     However, the upper and lower portions  13 ,  15  of the stick  12  of the prior art pointing stick devices  10 ,  30  are of a vertical, columnar shape, as is the corresponding aperture  21  of the base plate  20 . Thus, when a force is applied to the pointing stick device  10 ,  30 , the strain signals S z1  in the Z direction are too insignificant to use. Although, in the pointing stick device  30 , there is the cover ring  26  installed on the lower portion  15  of the stick  12 , it still cannot intensify the strain signals S z1  in the Z direction. Furthermore, adding the cover ring  26  on the prior art pointing stick device  30  requires additional materials, gluing and working hours, raising production costs. Accordingly, how to design a pointing stick device with increased sensitivity in the X, Y (horizontal) and Z (vertical) directions becomes the goal for a designer to strive for. 
     SUMMARY OF THE INVENTION 
     It is therefore a primary objective of the present invention to provide a pointing stick device with increased sensitivity in the vertical direction to solve the above mentioned problems. 
     In a preferred embodiment, the present invention provides a pointing stick device for use with a computer. The pointing stick device comprises: 
     a base plate having an aperture; 
     a stick having an upper portion, and a lower portion with a tapering section; 
     at least one strain gauge installed on the lower portion for sensing pressure and generating corresponding sensing signals; and 
     a binding compound filling the space between a periphery of the lower portion of the stick and the aperture of the base plate and covering the strain gauge, for fixing the lower portion of the stick vertically in the aperture of the base plate; 
     wherein when the stick is vertically depressed, the strain gauge installed on the periphery of the lower portion of the stick can sense vertical downward pressure from reaction forces transmitted through the binding compound and generate the corresponding sensing signals. 
     It is an advantage of the present invention that the pointing stick device can increase the strain gauge sensitivity, especially in the vertical direction. 
     These and other objectives and advantages of the present invention will no doubt become obvious to those of ordinary skill in the art after having read the following detailed description of the preferred embodiment that is illustrated in the various figures and drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a cross-sectional diagram of a prior art pointing stick device  10 . 
     FIG. 2 is a cross-sectional diagram of another prior art pointing stick device  30 . 
     FIG. 3 is a cross-sectional diagram of the pointing stick device  10  or  30  shown in FIG. 1 or FIG. 2 with a horizontal force acting on the stick  12 . 
     FIG. 4 is a cross-sectional diagram of the pointing stick device  10  or  30  shown in FIG. 1 or FIG. 2 with a vertical force acting on the stick  12 . 
     FIG. 5 is a cross-sectional diagram of the present invention first embodiment pointing stick device  40 . 
     FIG. 6 is a cross-sectional diagram of the present invention second embodiment pointing stick device  80 . 
     FIG. 7 is a cross-sectional diagram of the present invention third embodiment pointing stick device  100 . 
     FIG. 8 is a cross-sectional diagram of the present invention first embodiment pointing stick device  40  under a horizontal force in the X and Y directions. 
     FIG. 9 is a cross-sectional diagram of the present invention first embodiment pointing stick device  40  under a vertical force in the Z direction. 
     FIG. 10 is a cross-sectional diagram of the present invention second embodiment pointing stick device  80  under a horizontal force in the X and Y directions. 
     FIG. 11 is a cross-sectional diagram of the present invention second embodiment pointing stick device  80  under a vertical force in the Z direction. 
     FIG. 12 is a cross-sectional diagram of the present invention third embodiment pointing stick device  100  under a horizontal force in the X and Y directions. 
     FIG. 13 is a cross-sectional diagram of the present invention third embodiment pointing stick device  100  under a vertical force in the Z direction. 
     FIG. 14 is a cross-sectional diagram of the present invention fourth embodiment pointing stick device  120 . 
     FIG. 15 is a cross-sectional diagram of the present invention fourth embodiment pointing stick device  120  under a horizontal force in the X and Y directions. 
     FIG. 16 is a cross-sectional diagram of the present invention fourth embodiment pointing stick device  120  under a vertical force in the Z direction. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Please refer to FIG.  5 . FIG. 5 is a cross-sectional diagram of the present invention first embodiment pointing stick device  40 . The pointing stick device  40  comprises a stick  42 , a base plate  50 , at least one strain gauge  44  and a binding compound  52 . The stick  42  comprises an upper portion  43  and a lower portion  45 . The lower portion  45  has a tapering section  46 . The base plate  50  has an aperture  51  with a conic surface  58  for containing and fixing the lower portion  45  of the stick  42 . 
     The binding compound  52  is used to fill the space between the lower portion  45  of the stick  42  and the aperture  51  of the base plate  50  in order to fix the lower portion  45  of the stick  42  vertically in the aperture  51  of the base plate  50 . The binding compound  52  is a solid material, such as epoxy. 
     The tapering section  46  of the stick  42  has four faces, and a strain gauge  44  is installed on each of these four faces to sense the pressure on the four faces and generate the corresponding sensing signals. The lower portions of the strain gauges  44  extend into the lower region  45  of the stick  42  and are covered by the binding compound  52 . Thus, the lower portions of the strain gauges  44  can easily sense the vertical downward pressure of the stick  42 . 
     As known from the prior art method, the lower portions of the strain gauges  44  are electrically connected to a certain circuit (not shown) to output the generated sensing signals. If the base plates  50 ,  90  are printed circuit boards, the circuit can be directly printed on them; if the base plate  50 ,  90  is made of some other materials such as plastic or metal, the circuit can be printed on a flexible printed circuit board, and then glued to the base plate  50 ,  90 . 
     Please refer to FIG.  6 . FIG. 6 is a cross-sectional diagram of the present invention second embodiment pointing stick device  80 . The main difference between the pointing stick device  80  and the pointing stick device  40  shown in FIG. 5 is in the shape between the two apertures  51 ,  71  of the pointing stick device  40 ,  80  respectively. The aperture  71  is of a vertical, columnar-shaped surface  78  rather than the downwardly tapering conic shape of the aperture  51  of the pointing stick device  40 . The lower portion  45  of the stick  42  of the pointing stick device  80  shown in FIG. 6 still has a tapering section  46  like that of the pointing stick device  40  shown in FIG.  5 . 
     Please refer to FIG.  7 . FIG. 7 is a cross-sectional diagram of the present invention third embodiment pointing stick device  100 . The main difference between the pointing stick device  100  and the pointing stick device  40  shown in FIG. 5 is in the shape of the two lower portions  45 ,  65  of the pointing stick device  40 ,  100  respectively. The lower portion  65  of the stick  62  of the pointing stick device  100  is of a vertical, columnar-shaped surface  68  rather than the tapering section  46  of the lower portion  45  of the stick  42  of the pointing stick device  40 . The aperture  51  of the base plate  50  of the pointing stick device  100  shown in FIG. 7 is still a downwardly tapering conic shape, like that of the pointing stick device  40  shown in FIG.  5 . 
     The lower portion  65  of the stick  62  is a four-faced columnar shape, and the strain gauges  44  are installed on each of the four faces of the lower portion  65  to sense the pressure on the four faces and generate the corresponding sensing signals. The lower portions of the strain gauges  44  extend into the lower region  65  of the stick  62  and are covered by the binding compound  52 . Thus, the lower portions of the strain gauges  44  can easily sense the vertical downward pressure of the stick  62 . 
     Please refer to FIG. 8 to FIG. 13, FIG.  15  and FIG.  16 . These figures show the situations when horizontal and vertical forces are applied to the present invention pointing stick devices  40 ,  80 ,  100 ,  120 . The arrows labeled F x  and F y  represent the horizontal forces, and the arrows labeled F z  represent the vertical forces. These pointing stick devices can be used to control the movements and position of a cursor on a computer screen in the X and Y directions and the function of the cursor. The pointing stick devices can also control the three-dimensional movements of a cursor in the X, Y and Z directions. 
     Please refer to FIG.  8 . FIG. 8 is a cross-sectional diagram of the present invention first embodiment pointing stick device  40  under a horizontal force in the X and Y directions. The central line shown in FIG. 8 represents the bending direction of the stick  42  from the horizontal force. When the present invention pointing stick device  40  undergoes a horizontal force F x , F y  in the X and Y directions, as with the prior art pointing stick device shown in FIG. 3, the bending of the stick  42  from the horizontal force makes the strain gauges  44  generate bending strain signals S x1 , S y1 . In addition, the normal reaction forces R x , R y , generated from the horizontal force F x , F y  through the binding compound  52 , squeeze the strain gauges  44  to make the strain gauges  44  generate strain signals S x2 , S y2 . In this case, the totality of strain signals of the present invention pointing device  40  under a horizontal force in the X and Y directions is S x1 ,+S x2 , S y1 +S y2    
     Please refer to FIG.  9 . FIG. 9 is a cross-sectional diagram of the present invention first embodiment pointing stick device  40  under a vertical force in the Z direction. The central line shown in FIG. 9 represents the direction of compression of the stick  42  from the vertical force. When a vertical force F z  in the Z direction is applied to the present invention pointing stick device  40 , as with the prior art pointing stick device shown in FIG. 4, the compression of the stick  42  caused by the vertical force makes the strain gauges  44  generate compressive strain signals S z1 . In addition, the normal reaction forces R z , generated from the vertical force F z  through the binding compound  52 , squeeze the strain gauges  44 , causing the strain gauges  44  to generate additional strain signals S z2 . In this case, the totality of strain signals of the present invention pointing device  40  under a vertical force in the Z directions is S z1 ,+S z2 . 
     Please refer to FIG.  10 . FIG. 10 is a cross-sectional diagram of the present invention second embodiment pointing stick device  80  under a horizontal force in the X and Y directions. The central line shown in FIG. 10 represents the bending direction of the stick  42  from the horizontal force. When a horizontal force F x , F y  in the X and Y directions is applied to the present invention pointing stick device  80 , as with the prior art pointing stick device shown in FIG. 3, the bending of the stick  42  caused by the horizontal force causes the strain gauges  44  to generate bending strain signals S x1 , S y1 . In addition, the reaction forces R x ′, R y ′, a normal component (normal to the tapering section  46  surface) of the reaction forces R z , R y  generated from the horizontal force F x , F y  through the binding compound  52 , squeeze the strain gauges  44 , causing them to generate strain signals S x2 ′, S y2 ′. In this case, the totality of strain signals of the present invention pointing device  80  is S x1 +S x2 ′, S y1 +S y2 ′. 
     Please refer to FIG.  11 . FIG. 11 is a cross-sectional diagram of the present invention second embodiment pointing stick device  80  under a vertical force in the Z direction. The central line shown in FIG. 11 represents the direction of compression of the stick  42  from the vertical force. When a vertical force F z  in the Z direction is applied to the present invention pointing stick  80 , as with the prior art pointing stick device shown in FIG. 4, the compression of the stick  42  caused by the vertical force makes the strain gauges  44  generate compressive strain signals S z1 . In addition, the normal reaction forces R z ′, a normal component (normal to the tapering section  46  surface) of the reaction forces R z  generated from the vertical force F z  through the binding compound  52 , squeeze the strain gauges  44 , causing them to generate strain signals S z2 ′. In this case, the totality of strain signals of the present invention pointing device  80  under a vertical force in the Z direction is S z1 +S z2 ′. 
     Please refer to FIG.  12 . FIG. 12 is a cross-sectional diagram of the present invention third embodiment pointing stick device  100  under a horizontal force in the X and Y directions. The central line shown in FIG. 12 represents the bending direction of the stick  62  from the horizontal force. When a horizontal force F x , F y , in the X and Y directions is applied to the present invention pointing stick device  100 , as with the prior art pointing stick device shown in FIG. 3, the bending of the stick  62  makes the strain gauges  44  generate bending strain signals S x1 , S y1 . In addition, the reaction forces R x ″, R y ″,a normal component (normal to the column-shaped surface  68 ) of the reaction forces R x , R y (normal to the aperture&#39;s bowl-shaped surface  58 ) generated from the horizontal force F x , F y  through the binding compound  52 , squeeze the strain gauges  44 , causing the strain gauges  44  to generate strain signals S x2 ″, S y2 ″. In this case, the totality of strain signals of the present invention pointing device  100  under a horizontal force is S x1 +S x2 ″, S y1 +S y2 ″. 
     Please refer to FIG.  13 . FIG. 13 is a cross-sectional diagram of the present invention third embodiment pointing stick device  100  under a vertical force in the Z direction. The central line shown in FIG. 13 represents the direction of compression of the stick  62  from the vertical force. When a vertical force F z  is applied to the present invention pointing stick device  100 , as with the prior art pointing stick device shown in FIG. 4, the compression of the stick  62  causes the strain gauge  44  to generate compressive strain signals S z1 . Additionally, though, the normal reaction forces R z ″, a normal component (normal to the column-shaped surface  68 ) of the reaction forces R z . (normal to the aperture&#39;s bowl-shaped surface  58 ) generated from the vertical force F z , through the binding compound  52 , squeeze the strain gauges  44  to generate strain signals S z2 ″. In this case, the totality of strain signals of the present invention pointing device  100  under a vertical force in Z direction is S z1 +S z2 ″. 
     Please refer to FIG.  14 . FIG. 14 is a cross-sectional diagram of the present invention fourth embodiment pointing stick device  120 . The present invention fourth embodiment pointing stick device  120  comprises a stick  62 , a base plate  90 , a base stand  92 , at least one strain gauge  44  and a binding compound  52 . The stick  62  has an upper portion  63  and a lower portion  65 . The lower portion  65  is contained and fixed in an aperture  91  of the base stand  92 , vertically fixing the stick  62  on the base plate  90 . The base plate  90  has an aperture  93  with a downwardly tapering surface  98 , and the base stand  92  is installed in the aperture  93  of the base plate  90  by an insert-molding method. In this case, the interface between base stand  92  and the base plate  90  is slidably fixed rather than glue-fixed. 
     The binding compound  52  is used to fill the space between the lower portion  65  of the stick  62  and the aperture  91  of the base stand  92  in order to fix the lower portion  45  of the stick  42  vertically to the base plate  90 . The binding compound  52  is a solid material, such as epoxy. 
     Please refer to FIG.  15 . FIG. 15 is a cross-sectional diagram of the present invention fourth embodiment pointing stick device  120  under a horizontal force in the X and Y directions. The central line shown in FIG. 15 represents the bending direction of the stick  62  from the horizontal force. When a horizontal force F x , F y  in the X and Y directions is applied to the present invention pointing stick device  120 , as with the prior art pointing stick device shown in FIG. 3, the bending of the stick  62  makes the strain gauges  44  generate bending strain signals S x1 , S y1 . In addition, the reaction forces R x ′″, R y ′″, a normal component (normal to the column-shaped surface  68 ) of the reaction forces R x , R y  (normal to the downwardly tapering surface  98 ) generated by the horizontal force F x , F y  through the binding compound  52  and the base stand  92 , squeeze the strain gauges  44 , causing the strain gauges  44  to generate strain signals S x2 ′″, S y2 ′″. In this case, the totality of strain signals of the present invention pointing device  120  under a horizontal force in the X and Y directions is S x1 +S x2 ′″, S y1 +S y2 ′″. 
     Please refer to FIG.  16 . FIG. 16 is a cross-sectional diagram of the present invention fourth embodiment pointing stick device  120  under a vertical force in the Z direction. The central line shown in FIG. 16 represents the direction of compression of the stick  62  from the vertical force. When the present invention pointing stick device  120  is under a vertical force F z , as with the prior art pointing stick device shown in FIG. 4, the compression of the stick  62  makes the strain gauges  44  generate compressive strain signals S z1 . In addition, the normal reaction forces R z ′″, a normal component (normal to the column-shaped surface  68 ) of the reaction forces R z  (normal to the downwardly tapering surface  98 ) generated by the vertical force F z  through the binding compound  52  and the base stand  92 , squeeze the strain gauges  44 , causing them to generate strain signals S z2 ′″. In this case, the totality of strain signals of the present invention pointing device  120  under a vertical force in the Z direction is S z1 +S z2 ′″. 
     In the contrast to the prior art pointing stick device  10 ,  30 , the lower portion  45  of the stick  42  of the present invention pointing stick device  40 ,  80  has a tapering section  46 , and the lower portions of the strain gauges  44  extend into the tapering section  46  of the stick  42 . The strain gauges can easily sense the vertical downward pressure of the stick  42 . Likewise, although the lower portion  65  of the stick  62  of the present invention pointing stick device  100 ,  120  is of a vertical, columnar shape, the corresponding aperture  51 ,  93  is of a downwardly tapering conic shape and, therefore, the strain gauges can easily sense the vertical downward pressure of the stick  42 . The present invention pointing stick device  40 ,  80 ,  100 , or  120  increases the sensitivity of the strain signals in the Z direction, as well as in the X and Y directions. 
     Those skilled in the art will readily observe that numerous modifications and alterations of the device may be made while retaining the teachings of the invention. Accordingly, the above disclosure should be construed as limited only by the metes and bounds of the appended claims.