Patent Publication Number: US-8122783-B2

Title: Joystick and method of manufacturing the same

Description:
BACKGROUND OF THE INVENTION 
     This invention relates to joysticks. More specifically, this invention relates to a joystick using a three axis Hall Effect sensor in order to provide operation of a device. 
     Joysticks have been used for many years for varying operations. Joysticks not only have been used in gaming arts but additionally have been used in association with hydraulic devices such as cranes, fork lifts and the like. Specifically, joysticks allow for compact multi-dimensional actuation of a device. Known in the art are several types of joysticks including joysticks based on a “gimbal” mechanism wherein a magnet moves on a hemisphere centered at the IC (the sensor). Specifically, axial magnetization is provided wherein the flux density is provided through the following equations:
 
 B   x =SIN(α)COS(β)
 
 B   y =COS(α)SIN(β)
 
 B   z =COS(α)COS(β)
 
     Another type of joystick that exists is considered a “ball and socket” joint wherein the magnet moves on a hemisphere centered about the pivot point. Specifically, axial magnetization is provided wherein the flux density is described through a slightly more complex set of equations as can be shown as follows:
 
α=ATAN( V   x /(( K   z   V   z ) 2 +( K   t   V   y ) 2 ) 1/2 )
 
β=ATAN( V   y /(( K   z   V   z ) 2 +( K   t   V   x ) 2 ) 1/2 )
 
     In both applications multiple pieces are used in order to manufacture the joysticks. For example, in the “gimbal” mechanism a main shaft is provided with a magnet at the end wherein the shaft is attached to a movable device that has a center axis aligned with the three axis sensor. Thus, as the shaft pivots about this axis the movement of the magnet is detected by the three axis sensor. As a result of the multiple pieces provided to manufacture this joystick the manufacturing process is expensive. 
     Therefore, a principle object of the present invention is to provide an improved joystick that allows for sensing three axis directional movement. 
     Yet another object of the present invention is to provide a cost effective method of manufacturing a joystick. 
     These and other objects, features, or advantages of the present invention will become apparent from the specification and claims. 
     BRIEF SUMMARY OF THE INVENTION 
     A joystick having a movable member that is of one-piece construction that extends from a shaft portion to a spherical portion wherein the diameter of the shaft portion is less than the diameter of the spherical portion. An actuating member is secured to the shaft portion of the movable member to provide actuation of the movable member. A magnet is disposed within the spherical portion of the movable member at the bottom of the sphere extending upwardly and is off center from a center point of the spherical portion. A three axis sensor is disposed underneath, adjacent, and in spaced relation to the spherical portion and magnet of the movable member such that movement of the actuating member positions the magnet in a hemispherical pattern along the three axis sensor. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a side cut away perspective view of a joystick; and 
         FIG. 2  is a sectional view of a joystick. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The figure shows a joystick  10  that is comprised of an actuating member  12  such as a knob that is used to actuate a movable member  14  that contains a magnet  16  disposed therein such that movement of the movable member  14  is sensed by a three axis sensor  18 . The three axis sensor is electrically connected to a PBC (printed circuit board)  20  and the components are disposed within a housing  22  wherein a conical spring  24  connects the housing  22  to the movable member  14 . While the three axis sensor  18  may be any sensor that is able to detect three axes of movement in a preferred embodiment the three axis sensor  18  is a three axis Hall Effect sensor. Additionally, the actuating member  12  is able to move in any axial direction and is biased by the conical spring  24  to a non-actuated or neutral position wherein no net force is provided on the actuating member  12 . 
     The actuating member  12  is conically shaped having a centrally located concave portion  26  located on a top surface wherein a side wall  28  extends outwardly and downwardly from the centrally located concave portion  26 . Extending from the bottom of the actuating member  12  is a centrally located annular flange  30  that extends downwardly to receive the movable member  14 . A seal  32  contacts the bottom of the actuating member  12  and surrounds the housing  22  to connect the housing  22  to the actuating member  12 . As a result of the structure of the actuating member  12  movement in any direction is provided. 
     Movable member  14  is comprised of a shaft portion  34  and a spherical portion  36  that extends from the shaft portion  34 . Specifically, the shaft portion  34  has a diameter that is less than the diameter of the spherical portion  36 . Both the shaft portion  34  and spherical portion  36  are centered on a central axis  38  upon which the movable member could be rotated. The shaft portion  34  is at a first end  40  of the movable member  14  and has a rounded section  42  that rotatably fits within the annular flange  30  of the actuating member  12 . Meanwhile, the spherical portion  36  has a center point  44  located along the central axis  38  and extends to a second end  46  wherein the magnet  16  is located. Specifically, the magnet  16  extends from the second end  46  towards the center point  44  of the spherical portion  36 . In a preferred embodiment the magnet  16  is a cylindrical magnet and does not extend to the center point  44  and thus is considered off center. 
     Disposed below the magnet  16  and in spaced relation is a three axis sensor  18  that is electrically connected to a PCB (printed circuit board)  20 . Additionally, electrically connected on the printed circuit board  20  is a light emitting diode (LED)  48 . The operation of the LED  48  is independently controlled. The LED  48  can be triggered to indicate specific operating modes, or can be turned on continuously to provide backlighting. In a preferred embodiment the actuating member  12  and movable member  14  are both made of a transparent material such that when the light emitting diode emits light a user can detect the light. Further, in a preferred embodiment the transparent material is a plastic, and more specifically, injected molded plastic. 
     The housing  22  extends from a first end  50  to a second end  54  adjacent the printed circuit board  20 . The conical spring  24  extends between the first end  50  and around the shaft portion  34  of the movable member  14  to provide a biasing force on the actuating member  12 . Thus, the conical spring  24  always forces the actuating member  12  to a non actuated or neutral position. Additionally, surrounding the housing  22  is a retainer  56  adjacent the second end  54  of the housing  22  such that the joystick  10  may be placed into and retained within a device. 
     During the manufacturing process, plastic is injection molded in order to form the movable member  14 . Specifically, the plastic is molded to provide the shaft portion  34  and spherical portion  36  wherein the shaft portion has a diameter less than the diameter of the spherical portion  36 . During the injection molding process magnet  16  is over molded in the spherical portion such that the shaft portion  34 , spherical portion  36 , and magnet  16  are all within one single component. In a preferred embodiment the plastic is transparent such that the magnet  16  may be seen by an observer after injection molding occurs. 
     Next, during the manufacturing process the actuating member  12  is secured to the rounded section  42  of the movable member  14 . Next, the three axis sensor  18  is placed on a printed circuit board  20  and a light emitting diode  48  is placed adjacent to the three axis sensor  18 . At that point in time the printed circuit board  20  is placed underneath and adjacent to the second end  46  of the movable member  14  such that movement of the actuating member  12  positions the magnet  16  in a hemispherical pattern along the three axis sensor  18 . 
     The printed circuit board  20  and movable member  14  are disposed within housing  22  such that the printed circuit board  20  is adjacent the second end  54  of housing  22 . The conically shaped coil  24  is inserted between first end  50  of housing  22  and around the shaft portion  34  of the movable member  14  to provide the needed biasing force. At this point in time the seal  32  is secured between the actuating member  12  and housing  22 . Thus, the end result is joystick  10 . 
     The resulting joystick  10  provides a magnet  16  that is embodied into a movable member  14  for the use of triggering a three axis sensor  18  within a joystick application. The three axis sensor  18  senses the position of the magnet  16  in relationship to the surface center of the sensor  18 . The movement of the magnet position is achieved by the use of a ball and socket type design. 
     By using the injection molding process three elements; the magnet  16 , the spherical ball portion  36  and shaft portion  34  are all presented in a single component. The magnet  16  is positioned axially along the central axis  38  of the shaft portion  34  and is located off the center point  44  of the spherical portion  36 . This allows for the magnet  16  to be positioned in an infinitely hemispherical pattern along the surface of the sensor  18  about the center point  44  of the spherical portion  36  of the movable member  14  during actuation. 
     The use of this design also allows for axial rotation of the magnet  16  encompassing another potential function within the joystick  10 . Meanwhile, the incorporation of the light emitting diode  48  into the system using the printed circuit board  20  in conjunction with using translucent material for the actuating and movable members  12 ,  14  allows light to be emitted for operator interface. The use of plastic material, injection molding process and part incorporation, also reduces the overall cost of the joystick  10 . Preferably, the movable member and specifically the shaft portion  34  and spherical portion  36  are injection molded with the magnet  16  being over molded all within a single process or operation. 
     The above discussed joystick  10  and manufacturing process provide several advantages over previous joysticks provided. Specifically, the feature of the movable member  14  having both the shaft portion  34  and spherical portion  36  in one entity and comprised of an austenitic material provides reduction in manufacturing cost and allows the light emitting diode  48  to be seen when it is illuminated. Additionally, the location of the magnet  16  within the spherical portion  36  wherein the magnet is positioned axially along the central axis  38  of the shaft portion  34  and is located off center of the spherical portion  36  is new and provides for enhanced detection and operation. 
     Another feature and advantage is the incorporation of the axial rotation function with the spherical portion  36  and actuating shaft assembly. Further, the use of the conical compression spring  24  allows the spring  24  to act on the top housing and movable member  14  to bias the movable member  14  back to a neutral position. Specifically, the conical compression spring  24  has a bending load induced during actuation and after release the bending load reactive force is used to return the movable member  14  and actuating member  12  to neutral. 
     Another advantage is the use of the light emitting diode  48  within the joystick  10 . Thus, when the movable member and actuating member  14 ,  12  are made of a translucent material the emitted light can be carried to the point of operator interface. Therefore, at the very least all of the stated objectives have been met. 
     It will be appreciated by those skilled in the art that other various modifications could be made to the device without departing from the spirit and scope of this invention. All such modifications and changes fall within the scope of the claims and are intended to be covered thereby.