Abstract:
A directional input device with a light directing shaft that avoids wear and tear caused by physical contact between a shaft and a sensor surface. A directional input device according to the present teachings includes a light emitter and a shaft having a surface that reflects light from the light emitter. A directional input device according to the present teachings further includes a set of light sensing elements that are positioned to detect a position of the shaft by sensing light reflected from the shaft.

Description:
BACKGROUND  
       [0001]     Directional input devices may be employed in a variety of systems including computer systems, game systems, simulators, specialized vehicles, controllers, and remote control applications, to name a few examples. Examples of directional input devices include joysticks and joypads.  
         [0002]     A directional input device may include a shaft that may be manipulated by a user. A movement of a shaft may be used to provide a directional input for a computer system, game console, controller, etc. For example, a shaft of a directional input device may be moved to the left to indicate a “left” input. Similarly, a shaft of a directional input device may be moved to the right, up, or down, to provide corresponding directional inputs.  
         [0003]     A directional input device may include a sensor surface for sensing the movements of its shaft. For example, a sensor surface may include a set of structures that make physical contact with a shaft and form electrical circuits that indicate the up, down, left, right, etc., positions of the shaft. Unfortunately, the cumulative effects of physical contact between a moving shaft and a sensor surface may cause wear and tear in the structures on the sensor surface and the shaft. The wear and tear of a sensor surface and a shaft may cause failures when detecting movements of a shaft with consequential failures in detecting directional inputs from a user.  
       SUMMARY OF THE INVENTION  
       [0004]     A directional input device with a light directing shaft is disclosed that avoids wear and tear caused by physical contact between a shaft and a sensor surface. A directional input device according to the present teachings includes a light emitter and a shaft having a surface that reflects light from the light emitter. A directional input device according to the present teachings further includes a set of light sensing elements that are positioned to detect a position of the shaft by sensing light reflected from the shaft.  
         [0005]     Other features and advantages of the present invention will be apparent from the detailed description that follows.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0006]     The present invention is described with respect to particular exemplary embodiments thereof and reference is accordingly made to the drawings in which:  
         [0007]      FIGS. 1   a - 1   b  show a top view and a side view, respectively, of a directional input device according to the present teachings;  
         [0008]      FIG. 2  shows light rays reflected from a reflecting surface of a shaft according to the present teachings;  
         [0009]      FIG. 3  shows a top view of another embodiment of a directional input device according to the present teachings;  
         [0010]      FIG. 4  shows a top view of yet another embodiment of a directional input device according to the present teachings;  
         [0011]      FIG. 5  shows a top view of another embodiment of a directional input device according to the present teachings;  
     
    
     DETAILED DESCRIPTION  
       [0012]      FIGS. 1   a - 1   b  show a top view and a side view, respectively, of a directional input device  10  according to the present teachings. The directional input device  10  includes a shaft  12  having a reflecting surface  14 , e.g. a reflective coating, that enables the shaft  12  to direct light emitted from a light emitter  30  back onto a sensor surface  18  in response to manipulation of the shaft  12  by a user.  
         [0013]     The sensor surface  18  includes a set of light sensing elements  20 - 23 , e.g. photodiodes. The light sensing elements  20 - 23  are placed at selected positions with respect to a set of x-y axes of the sensor surface  18 . The positions of the light sensing elements  20 - 23  are selected to detect movements of the shaft  12  with respect to the x-y axes by detecting light from the light emitter  30  that is reflected by the reflecting surface  14 .  
         [0014]     A tilting movement of the shaft  12 , e.g. a tilting movement indicated by an arrow  16 , causes reflected light from the light emitter  30  to illuminate one of the light sensing elements  20 - 23  depending on the movement of the shaft  12 . A pair of amplifiers  40 - 42  detect which of the light sensing elements  20 - 23  is illuminated by detecting the high or low signal states of the light sensing elements  20 - 23 .  
         [0015]      FIG. 2  shows an example set of light rays  100  that depict reflected from the reflecting surface  14  of the shaft  12  when the shaft  12  is rotated to the right, i.e. the +X direction. In the +X position of the shaft  12 , the light sensing element  20  is illuminated with reflected light from the light emitter  30 . As a consequence, the light sensing element  20  functions as a +X sensor, e.g. for an “Right” movement a joypad or joystick.  
         [0016]     Similarly, the light sensing element  22  functions as a −X sensor, e.g. for a “Left” movement of a joypad or joystick, because it is illuminated when the shaft  12  is moved to the left. Likewise, the light sensing elements  21  and  23  function as −Y (Down) and +Y (Up) sensors for movements of the shaft  12 .  
         [0017]     Table 1 summarizes the signal states of the light sensing elements  20 - 23  in response to a set of predetermined positions of the shaft  12 .  
                                       TABLE 1                                   +X   −X   +Y   −Y   Position                           Low   Low   Low   Low   Center                           (Home)           High   Low   Low   Low   Right           Low   High   Low   Low   Left           Low   Low   High   Low   Up           Low   Low   Low   High   Down           High   Low   High   Low   Upper                           Right           High   Low   Low   High   Lower                           Right           Low   High   High   Low   Upper Left           Low   High   Low   High   Lower Left                      
 
         [0018]      FIG. 3  shows a top view of another embodiment of the directional input device  10 . In this embodiment, the sensor surface  18  includes the light sensing elements  20 - 23  as an inner set of light sensors and further includes a set of light sensing elements  50 - 53  as an outer set of light sensors. The light sensing elements  50 - 53  are placed at selected positions with respect to the x-y axes of the sensor surface  18  to detect far movements of the shaft  12 , e.g. for an acceleration function of the directional input device  10 . A pair of amplifiers  60 - 62  detect which of the light sensing elements  50 - 53  is illuminated.  
         [0019]     For example, a movement of the shaft  12  to the far right, i.e. the far +X direction, illuminates the light sensing element  50 . As a consequence, the light sensing element  50  functions as a Far +X sensor (e.g. Accelerate Right). Similarly, the light sensing element  52  functions as a Far −X sensor (e.g. Accelerate Left) because it is illuminated when the shaft  12  is moved to the far left. Likewise, the light sensing elements  51  and  53  function as Far −Y (e.g. Accelerate Down) and Far +Y (e.g. Accelerate Up).  
         [0020]     Table 2 summarizes the signal states of the light sensing elements  20 - 23  and  50 - 53  in response to a set of predetermined positions of the shaft  12 .  
                                               TABLE 2                       Far +X   Far −X   Far +Y   Far −Y   Near +X   Near −X   Near +Y   Near −Y   Position                   Low   Low   Low   Low   Low   Low   Low   Low   Center                                       (Home)       Low   Low   Low   Low   High   Low   Low   Low   Right       Low   Low   Low   Low   Low   High   Low   Low   Left       Low   Low   Low   Low   Low   Low   High   Low   Up       Low   Low   Low   Low   Low   Low   Low   High   Down       Low   Low   Low   Low   High   Low   High   Low   Upper                                       Right       Low   Low   Low   Low   High   Low   Low   High   Lower                                       Right       Low   Low   Low   Low   Low   High   High   Low   Upper Left       Low   Low   Low   Low   Low   High   Low   High   Lower Left       High   Low   Low   Low   High   Low   Low   Low   Accelerate                                       Right       Low   High   Low   Low   Low   High   Low   Low   Accelerate                                       Left       Low   Low   High   Low   Low   Low   High   Low   Accelerate                                       Up       Low   Low   Low   High   Low   Low   Low   High   Accelerate                                       Down       High   Low   High   Low   High   Low   High   Low   Accelerate                                       Upper                                       Right       High   Low   Low   High   High   Low   Low   High   Accelerate                                       Lower                                       Right       Low   High   High   Low   Low   High   High   Low   Accelerate                                       Upper Left       Low   High   Low   High   Low   High   Low   High   Accelerate                                       Lower Left                  
 
         [0021]      FIG. 4  shows a top view of yet another embodiment of the directional input device  10 . In this embodiment, the light sensing elements  20 - 23  and  50 - 53  have respective apertures  60 - 63  and  70 - 73  for receiving light reflected from the light emitter  30 . Each aperture  60 - 63  and  70 - 73  has a pie shape. The apertures  60 - 63  form an inner circular light collection area for sensing near +X, near −X, near +Y, and near −Y movements of the shaft  12 . The apertures  70 - 73  form an outer circular light collection area for sensing far +X, far −X, far +Y, and far −Y movements of the shaft  12 .  
         [0022]      FIG. 5  shows a top view of another embodiment of the directional input device  10 . In this embodiment, the sensor surface  18  includes a set of light sensing elements  80 - 87  that are positioned to detect down, lower left, left, upper left, up, upper right, right, and lower right movements, respectively, of the shaft  12 . The light sensing elements  80 - 87  have respective apertures  90 - 97  for receiving light reflected from the light emitter  30 . Each aperture  90 - 97  has a sector shape with a variable width so that it accepts more light at its far end away from a center position of the light emitter  30  in comparison to the amount of light it accepts at its end near the center position. Each aperture  90 - 97  even at its widest is selected to be narrower than the width of the light beam reflected from the light emitter  30 . An illumination of the wide end of each aperture  90 - 97  yields a larger sensor signal than illumination if its narrow end. As a consequence, the magnitude of a sensor signal yielded by each light sensing element  80 - 87  indicates a relative position, i.e. near or far, of a light beam along its length. Therefore, the strength of the sensor signals from the light sensing elements  80 - 87  in this embodiment indicate the relative of movement of the shaft  12  with respect to the length of the corresponding aperture  90 - 97  and may be used, for example, as an accelerate function of the directional input device  10 .  
         [0023]     The foregoing detailed description of the present invention is provided for the purposes of illustration and is not intended to be exhaustive or to limit the invention to the precise embodiment disclosed. Accordingly, the scope of the present invention is defined by the appended claims.