Abstract:
A trackball includes a first circuit module adapted to control the amount and direction of movement of a pointer on a computer screen upon rotation of a ball on the first circuit module, and a second circuit module disposed below the first circuit module and adapted to make a menu selection upon pressing of the ball.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    The present invention relates to a trackball and, more particularly, to a such a trackball, which enables the operator to manipulate objects on the screen and to make menu selections simply by means of rotating and pressing the ball.  
           [0002]    In early days, the pointer on the computer screen of a computer system is controlled by the up, down, left and right keys. This pointer control method does not fit window operation environment. Therefore, optical mouse was developed. The mouse is connected to the computer by a wire, and incorporates one or more buttons that can be pressed. Moving the mouse across a flat surface causes a corresponding movement of the pointer. In this way, the operator can manipulate objects on the screen and make menu selections. The mouse is still not satisfactory in function because it must be moved across a flat surface when controlling the pointer on the computer screen. In order to eliminate this drawback, trackball was developed.  
           [0003]    [0003]FIG. 1 shows a trackball according to the prior art. This structure of trackball comprises a circuit module  1   a,  a two-dimensional optical shaft unit  2   a,  a ball holder  3   a,  a ball  4   a,  and a switch  5   a.  This trackball carries out the same function as a mouse, but remains stationary. However, when making a menu selection, the user must shift the finger to the enter button and then press the enter button. After a menu selection, the user must shift back the finger from the enter button to the ball again. This operation method is still not satisfactory in function.  
         SUMMARY OF THE INVENTION  
         [0004]    The present invention has been accomplished under the circumstances in view. It is the main object of the present invention to provide a trackball, which enables the user to directly make a menu selection simply by pressing the ball without leaving the finger from the ball. According to the present invention, the trackball comprises a first circuit module pivoted to upright support means in the housing of the trackball and adapted to control the amount and direction of movement of a pointer on a computer screen upon rotation of a ball on the first circuit module, and a second circuit module disposed below the first circuit module with a switch thereon supporting the free end of the first circuit module and adapted to make a menu selection upon pressing of the ball. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0005]    [0005]FIG. 1 is a perspective view showing the internal structure of a prior art trackball.  
         [0006]    [0006]FIG. 2 is an elevational view of a trackball constructed according to the present invention.  
         [0007]    [0007]FIG. 3 is a perspective view of the present invention, showing the top cover shell of the housing removed from the bottom cover shell.  
         [0008]    [0008]FIG. 4 is an exploded view of the present invention (the housing excluded).  
         [0009]    [0009]FIG. 5 is a longitudinal view in section in an enlarged scale of a part of the present invention.  
         [0010]    [0010]FIG. 6 is similar to FIG. 5 but showing the trackball operated.  
         [0011]    [0011]FIG. 7 is a transverse view in section in an enlarged scale of a part of the present invention.  
         [0012]    [0012]FIG. 8 is similar to FIG. 7 but showing the trackball operated. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0013]    Referring to FIGS. from  2  through  5 , a trackball is shown comprising a housing  6  formed of a top cover shell  61  having a circular opening  63  and a bottom cover shell  62 , and a circuit module unit, which is comprised of a first circuit module  11  and a second circuit module  12  respectively mounted in the housing  6  at different elevations. The first circuit module  11  incorporates a two-dimensional optical shaft unit  2  and a ball  4 . The aforesaid statement is similar to a conventional trackball. The features of the present invention are outlined hereinafter.  
         [0014]    The first circuit module  11  comprises a horizontal pivot shaft  31  disposed at one side  10  thereof and pivotally supported on upright supports  64 ; 65  inside the bottom cover shell  62 , and ball holder  3  adapted to support the ball  4 , i.e., the first circuit module  11  has a fixed end pivoted to the upright supports  64 ; 65  of the bottom cover shell  62  and a free end suspending above the second circuit module  12 . The ball  4  is a transparent spherical member rotatably mounted in the ball holder  3  and partially projecting out of the circular opening  63  of the top cover shell  61  of the housing  6 .  
         [0015]    The second circuit module  12  comprises a first switch  5  functions as enter button to make a menu selection. The first switch  5  is disposed at one side opposite to the pivot shaft  31  of the ball holder  3  and adapted to support the free end of the first circuit module  11 , i.e., the first circuit module  11  is supported on three bearing points above the second circuit module  12 . These three bearing points include a first bearing point at the first switch  5  of the second circuit module  12 , and second and third bearing points at the upright supports  64 ; 65  of the bottom cover shell  62 . In other words, the first circuit module  11  has a fixed end pivoted to the upright supports  64 ; 65  and a free end supported on the first switch  5 . When the user presses the ball  4 , the first circuit module  11  is lowered against the first switch  5  (see FIGS. 5 and 6 or FIGS.  7  and  8 ), thereby causing the first switch  5  to output a signal to the connected computer to make a menu selection.  
         [0016]    The second circuit module  12  further comprises a second switch  52  and a third switch  53  corresponding to the left button  66  and right button  67  of the top cover shell  61 , a fourth switch  54  and a fifth switch  55  at the front side thereof corresponding to the front button  68  of the bottom cover shell  62 . By means of pressing either end of the front button  68  of the bottom cover shell  62 , the fourth switch  54  or the fifth switch  55  is triggered to output a respective signal to the computer. The fourth switch  54  and the fifth switch  55  are mounted on a third circuit module  13 , which is vertically fastened to the front side of the second circuit module  12  and inserted into a plug hole  60  inside the bottom cover shell  62 . The second circuit module  12  has two rear positioning holes  14  respectively coupled to respective locating rods  69  inside the bottom cover shell  62 . During operation, the fourth switch  54  limits the down stroke of the first circuit module  11  when the user presses the ball  4  to lower the first circuit module  11  against the first switch  5 . After each down stroke of the first circuit module  11 , the spring power of the spring-supported press button of the first switch  5  immediately forces the first circuit module  11  upwards to its former position.  
         [0017]    The second circuit module  12  comprises a LED (light emitting diode)  16  aimed at the center through hole  32  of the ball holder  3  and the bottom side of the ball  4 . During the operation of the trackball, the light of the LED  16  passes through the transparent ball  4 , producing a lighting effect. The housing  6  is orthopedically engineered to fit the palm of the hand for comfortable operation.  
         [0018]    A prototype of trackball has been constructed with the features of FIGS.  2 ˜ 8 . The trackball functions smoothly to provide all of the features discussed earlier.  
         [0019]    Although a particular embodiment of the invention has been described in detail for purposes of illustration, various modifications and enhancements may be made without departing from the spirit and scope of the invention. Accordingly, the invention is not to be limited except as by the appended claims.