Patent Publication Number: US-6667734-B2

Title: Joy stick

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to a joy stick, and more particularly to the joy stick in which restoring accuracy of cranks arranged in a casing has been enhanced. 
     An example of a related joy stick of this type will be described referring to FIGS. 9 and 10. In the drawings, a joy stick  1  is composed of a base table  2 , a helical spring  3  and a spring holder  4  mounted on the base table  2  in this order, a cam  5  received in a recess  4   a  formed on an upper face of the spring holder  4 , and an operating stick  6  attached to the cam  5  at its lower part, and a box-like casing  7  which is open at its lower face and attached to the base table  2  at its lower end part. 
     In the casing  7 , there is disposed a lower crank  8 . Shafts  8   a  projecting from both ends of the lower crank  8  are rotatably engaged in axial bores which are formed in a left side plate  7   a  and a right side plate  7   b  of the casing  7 . 
     The lower crank  8  is provided in its central area with a hole  8   b  through which the cam  5  is adapted to be idly inserted. A pin  9  is passed through the lower crank  8  and the cam  5  so that the lower crank  8  and the cam  5  can freely pivot in a direction of an arrow X around the pin  9 . Therefore, the spring holder  4  is biased upward by the helical spring  3 , and accordingly, the cam  5  and the lower crank  8  are always pressed upward by the spring holder  4 . 
     Moreover, an upper crank  10  which perpendicularly intersects the lower crank  8  is disposed in the casing  7 . Shafts  10   a  projecting from the upper crank  10  in a direction to the back and the forth in the drawing are rotatably engaged in axial bores (not shown) which are formed in a front side plate (not shown) and a back side plate  7   c  of the casing  7 . 
     In a central area of the upper crank  10 , there is formed a guide groove  10   b  in which the operating stick  6  is idly engaged so as to be pivotable in the direction of the arrow Y. In addition, a variable resistor  11  for detecting rotation angles of the lower clank  8  is provided on an outer face of the left side plate  7   a  of the casing  7 . A rotary shaft (not shown) of the variable resistor  11  is coupled to the left hand shaft  8   a  of the lower crank  8 . 
     In the same manner, a variable resistor (not shown) for detecting rotation angles of the upper clank  10  is provided on the back side plate  7   c  of the casing  7 , and the variable resistor is coupled to one of the shafts  10   a  of the upper crank  10 . 
     In the joy stick constructed in this manner, by operating the operating stick  6  in the direction of the arrow Y, the lower crank  8  is rotated as indicated by an arrow A, and the rotation angles are detected by the variable resistor  11  thereby controlling an object to be controlled. 
     Similarly, by operating the operating stick  6  in the direction of the arrow X, the upper crank  10  is rotated, and the rotation angles are detected by the variable resistor. In conducting these operations, when the operating stick  6  is tilted to the left, for example, as shown in FIG. 10, the spring holder  4  is pressed by the cam  5  which rotates along with the operating stick  6 , and thus, the helical spring  3  will be compressed. 
     When the operating stick  6  in this state is released by an operator&#39;s finger, the operating stick  6  will be restored to a neutral position as shown in FIG. 9, along with the cam  5  by resilient restoring force of the helical spring  3 . When the lower crank  8  is rotated by operating the operating stick  6  in the direction of arrow Y, the operating stick  6  will act in the same manner. 
     In addition to a problem of the above described joy stick  1  that the guide groove  10   b  of the upper crank  10  may be worn by repeated operations of the operating stick  6 , but there is also a problem that the restored position of the upper crank  10  may change due to a backlash or a clearance between components in terms of accuracy, and the variable resistor  11  may not be accurately restored to the determined neutral position, resulting in inaccurate output of the control of the joy stick  1 . 
     SUMMARY OF THE INVENTION 
     It is therefore an object of the present invention is to provide a joy stick which is excellent in restoring accuracy of the cranks to the neutral position and free from such confusion in the control. 
     In order to achieve the above object, according to the present invention, there is provided a joy stick, comprising: 
     an operating stick; 
     a first crank, which supports the operating stick so as to be pivotable in a first direction; 
     first flat faces, which are formed at lower both end portions in the first direction of the first crank; 
     a second crank, which supports the operating stick so as to be pivotable in a second direction which is perpendicular to the first direction; 
     second flat faces, which are formed at lower both end portions in the second direction of the second crank; 
     a restoration member, which is arranged coaxially with the operating stick which is situated at a neutral position thereof, the restoration member including a flat top face brought into contact with the first flat faces and the second flat faces; and 
     a spring member, which is arranged coaxially with the restoration member, the spring member urging the restoration member toward the first flat faces and the second flat faces. 
     In this configuration, the restoration member is biased upward by the spring member, thus enabling the first crank and the second crank to be accurately restored to the neutral position. Therefore, irrespective of wear of the first crank and the second crank, the restoring accuracy of the first crank and the second crank can be maintained. At the same time, the number of the components will be decreased, thus attaining a low manufacturing cost. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The above objects and advantages of the present invention will become more apparent by describing in detail preferred exemplary embodiments thereof with reference to the accompanying drawings, wherein like reference numerals designate like or corresponding parts throughout the several views, and wherein: 
     FIG. 1 is a longitudinal sectional view showing one embodiment of a joy stick according to the invention; 
     FIG. 2 is an exploded perspective view of the joy stick; 
     FIG. 3 is a partially-exploded perspective view of the joy stick; 
     FIG. 4A is a back side view of a base table incorporated in the joy stick; 
     FIG. 4B is a left side view of the base table; 
     FIG. 4C is a plan view of the base table; 
     FIG. 4D is a right side view of the base table; 
     FIG. 4E is a front view of the base table; 
     FIG. 4F is a sectional view taken along a line F—F of FIG.  4 C. 
     FIG. 5A is a plan view of a first crank incorporated in the joy stick; 
     FIG. 5B is a front view of the first crank; 
     FIG. 5C is a right side view of the first crank; 
     FIG. 6A is a plan view of a second crank incorporated in the joy stick; 
     FIG. 6B is a front view of the second crank; 
     FIG. 6C is a right side view of the second crank; 
     FIG. 6D is a bottom view of the second crank; 
     FIG. 7A is a detailed view of a spring holder incorporated in the joy stick; 
     FIG. 7B is a sectional view taken along a line G—G of FIG. 7A; 
     FIG. 8 is a detailed view showing an operating stick incorporated in the joy stick; 
     FIG. 9 is a longitudinal sectional view of a related joy stick; and 
     FIG. 10 is a longitudinal sectional view showing operation of the related joy stick. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Now, one embodiment of the joy stick according to the invention will be described in detail referring to the accompanying drawings. As shown in FIGS. 1 and 2, a joy stick  20  includes a base table  22  fitted to an open side of a casing  21 , a first crank  23  and a second crank  24  perpendicularly intersecting with each other and disposed in the casing  21 . A spring holder  26  is pressure contacted to respective lower faces of opposite end parts of the first crank  23  and the second crank  24 . A helical spring  27  is interposed between the spring holder  26  and a groove  25  formed in the base table  22  (see FIGS. 4A to  4 F). 
     The first crank  23  has shafts  28  projecting from both ends thereof as shown in FIGS. 5A,  5 B and SC and rotatably engaged in axial bores  30 A,  31 A formed in side plates  29 A,  29 B of the casing  21  as shown in FIG.  3 . In the same manner, the second crank  24  has shafts  33  projecting from both ends thereof as shown in FIGS. 6A,  6 B,  6 C and  6 D and rotatably engaged in axial bores  31 B,  31 B formed in left and right side plates  29 C,  29 D of the casing  21  as shown in FIG.  3 . 
     The first crank  23  is further provided with arm portions  32  at base ends of the shafts  28 , and flat face portions  32   a  are formed on lower faces of the arm portions  32 . In the same manner, the second crank  24  is provided with arm portions  34  at base ends of the shafts  33 , and flat face portions  35  are formed on lower faces of the arm portions  34 . The spring holder  26  is resiliently abutted against these flat face portions  32   a,    35  by means of the helical spring  27 . Further, as shown in FIGS. 7A and 7B, an annular groove  36  is formed at a lower face of a circumferential part of the spring holder  26  to idly receive the helical spring  27 . 
     As shown in FIGS. 6A to  6 D, the second crank  24  is provided with a connecting portion  37  for coupling the arm portions  34 . A shaft  38  is provided at a center of the connecting portion  37 , and an arcuate groove  39  is formed around an outer circumference of the shaft  38 . A groove  41  and a head  42  formed at a distal end of an operating stick  40  (see FIG. 8) are engaged with the shaft  38  and the groove  39 , and at the same time, an arm portion  43  of the operating stick  40  passes through a guide groove  45  formed between guide portions  44  of the first crank  23 , and projects upward through a stick hole  31  C formed in an upper plate  29  of the casing  21 . 
     One of coupling portions  46  shown in FIGS. 1 and 6A to  6 D is coupled to a variable resistor  47 . Similarly, one of coupling portions  48  shown in FIGS. 5A to  5 C is connected to a variable resistor (not shown). 
     Now, operation of the joy stick  20  will be described. As shown in FIG. 1, the operating stick  40  is grasped and tilted to the left and the right in a direction of an arrow B (or an arrow D in FIG. 3) thereby to rotate the first crank  23 , and the angle of the rotation is detected by the variable resistor (not shown). In the same manner, the operating stick  40  is tilted back and forth in a direction of an arrow C (or an arrow E in FIG. 3) thereby to rotate the second crank  24 , and the angle of the rotation is detected by the variable resistor  47 . 
     By releasing the grasp of the operating stick  40 , the first crank  23  and the second crank  24  are restored to a neutral position as shown in FIG. 1 by resilient restoring force of the helical spring  27 . On this occasion, the spring holder  26  which swings following compressive restoring action of the helical spring  27  always resiliently abuts against the flat face portions  32   a  of the first crank  23  and the flat face portions  35  of the second crank  24  respectively to rotate the first crank  23  and the second crank  24 . Therefore, an angle of the restoration will be constant, irrespective of engaging accuracy or progress of wear of the first crank  23  and the second crank  24  with respect to the operating stick  40 . 
     In the meantime, the cams and pins which have been incorporated in the related joy stick are not required for assembling the joy stick of the present invention, and further, because the assembling work can be conducted from only one direction as shown in FIG. 2, the joy stick can be easily assembled and number of the components will be decreased. 
     When manufacturing the components, because the engaging accuracy and wear of the first crank  23  and the second crank  24  with respect to the operating stick  40  will not badly affect the restoring accuracy, it will be possible to loosen the engaging accuracy, and production and quality control will be made easier. Further, because the spring holder  26  and the flat face portions  32   a,    35  are tightly brought into face-to-face contact with each other and will not slide, it will be possible to improve operability of the operating stick  40 . Thus, it will be possible to decrease the resilient restoring force of the helical spring  27 , and the joy stick  20  can be made compact as small as possible. 
     Although in the above described embodiment, the invention has been described referring to an example in which the variable resistors are employed as detecting means for detecting the rotation angles of the upper and the lower cranks, the detecting means should not be restricted to the variable resistor, but may be an encoder of a rotary type, for example. 
     Although the present invention has been shown and described with reference to specific preferred embodiments, various changes and modifications will be apparent to those skilled in the art from the teachings herein. Such changes and modifications as are obvious are deemed to come within the spirit, scope and contemplation of the invention as defined in the appended claims.