Abstract:
A key mechanism for an input device includes a key having an axle that is coupled to a guide in the housing of the input device in a manner such that the key pivots about the axle when the key is depressed, while allowing the axle to simultaneously move up or down within the guide.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The present invention relates to a key mechanism, and in particular, to a key mechanism fitted in a computer input device. The key has an adjustable suspended axle positioned on the input device in a manner so that it can be pivoted and moved linearly.  
           [0003]    2. Description of the Prior Art  
           [0004]    Nowadays, the computer mouse has become almost a standard peripheral device that is equipped with every computer system. Besides functioning to move the cursor on the screen, the computer mouse also performs a very important and extremely useful function in ticking icons on the screen. Therefore, it is desirable to upgrade the key mechanism of a computer mouse to provide (1) a better feel of touch, (2) a stable depressing motion, and (3) a key mechanism that occupies less space within the housing of the mouse.  
           [0005]    [0005]FIG. 1 illustrates a prior art key mechanism structure for a computer mouse  9 . The computer mouse  9  has an upper housing  91  and a lower housing  92  that together house several conventional micro switches and other conventional mouse components  94 , such as a PC board, a ball, etc. The computer mouse  9  has several keys  95 , with each key  95  having a protrusion  951  extending down through the upper housing  91  and contacting a micro switch  96 . A fixed-arm mechanism is used to provide a positioning and depressing function for the keys  95 . According to this fixed-arm mechanism, each key  95  has an extending arm  952  having a located opening  953 . The extending arm  952  extends into the interior of the computer mouse  9  and is coupled to a positioning pillar  911  of the upper housing  91 . The extending arm  952  is also supported by a hook  912  extending down from the upper housing  91 . Thus, the hook  912  acts as a fulcrum while the key  95  is depressed so as to function like a fixed-arm structure. When a key  95  is depressed by a user, the key  95  will downwardly curve the extending arm  952  to activate the micro switch  96 , which not only provides a rebounding force, but also relocates the key  95  and its deformed extending arm  952 .  
           [0006]    In order to provide better feel of the touch on each key  95 , and to upgrade the stability of the depressing motion on the key  95  (i.e., to achieve the accurate rebounding of the micro switch  96  when the key  95  is depressed), the extending arm  952  should be as long as possible such that the user will not feel the differences of the rebounding of the key  95  when the user applies force on any part of the key  95 . However, the recent trend has seen the sizes of various computer input devices (including for computer mice) become smaller. In addition, add-on equipments and peripherals have become more and more popular, such as data gathering devices and storing devices, finger print identification devices, smart card reading devices, and memory card/memory stick reading devices. Therefore, given the size restrictions of computer input devices, it will be difficult to fit these devices inside the computer input device. To overcome this disadvantage, one possible solution is to keep the extending arm  952  short, but the user will need to endure a less-than-optimum feel when touching (i.e., depressing) the key  95 , and the user may need to exert a greater force if the depressed portion of the key  95  is close to the hook  912 . A second possible solution is to thin the thickness of the extending arm  952  near the hook  912 , but this may lead to deformation of the extending arm  952  during molding or after extended use by the user.  
         SUMMARY OF THE DISCLOSURE  
         [0007]    It is an object of the present invention to provide a suspended axle key mechanism for use in an input device that provides a better feel of touch, a stable depression motion, and which occupies less space inside the input device.  
           [0008]    It is another object of the present invention to provide keys for an input device that can be easily assembled.  
           [0009]    In order to accomplish the objects of the present invention, the present invention provides a key mechanism for an input device that includes a key having an axle that is coupled to a guide in the housing of the input device in a manner such that the key pivots about the axle when the key is depressed, while allowing the axle to simultaneously move up or down within the guide. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0010]    [0010]FIG. 1 is a sectional view of a key mechanism of a conventional input device.  
         [0011]    [0011]FIG. 2 is a perspective view of an input device according to the present invention.  
         [0012]    [0012]FIG. 3 is a cross-sectional view of the input device of FIG. 2 taken along line A-A thereof.  
         [0013]    [0013]FIG. 4 is an exploded perspective view of the input device of FIG. 2. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0014]    The following detailed description is of the best presently contemplated modes of carrying out the invention. This description is not to be taken in a limiting sense, but is made merely for the purpose of illustrating general principles of embodiments of the invention. The scope of the invention is best defined by the appended claims.  
         [0015]    FIGS.  2 - 4  illustrate one preferred embodiment for the present invention, which is embodied in the form of a computer input device  1 , which can be an optical computer mouse or a traditional computer mouse that operates with a roller ball. The input device  1  has a main body or housing  10  defining an interior space  100 . The input device  1  also has a cover  20 , a plurality of keys  30 , a plurality of micro switches  72 , and a printed circuit board (PCB) 71 that embodies other known and conventional components of an input device (which are not described in any further detail because such components and their operations are well-known in the art). The micro switches  72  can be coupled to the PCB 71, and both the micro switches  72  and the PCB  71  are located inside the space  100 . Each of the keys  31  has a protrusion  32  extending down through a corresponding aperture  109  provided on the main body  10 . Each protrusion  32  corresponds to one of the micro switches  72 . Each protrusion  32  slightly contacts its corresponding micro switch  72 , and activates the micro switch  72  when the corresponding key  31  is depressed.  
         [0016]    Referring now to FIGS. 3 and 4, each of the keys  31  has a generally L-shaped arm  33  that is connected along an inner end to the key  31 , with a suspended axle  34  connected to each arm  33 . In one possible embodiment of the present invention, the key  31 , the arm  33  and the suspended axle  34  are molded in one piece. At least one opening  19  is provided in the upper surface of the main body  10 . Each opening  19  corresponds to one key  31 , so that if, for example, two keys  31  are provided, then two corresponding openings  19  will be provided.  
         [0017]    At least one well  191  is positioned inside the interior space  100 , with each well  191  being accessed by a corresponding opening  19 . Each well  191  is defined by at least two opposing walls  192  and  193 . A vertical groove  108  is provided in each wall  192  and  193 , with each opposing vertical groove  108  in the same well  191  being aligned with each other. A recess  18  is positioned inside each well  191  beneath the grooves  108 . During assembly, each arm  33  is fitted into the opening  19  and the axle  34  is pivotally coupled to the opposing grooves  108  in the opposing walls  192  and  193  of one of the wells  191 . When the axle  34  is pivotally fitted inside the pair of grooves  18 , the axle  34  can be moved up and down within the grooves  18 . In other words, when each key  31  is depressed, the key  31  is capable of not only turning pivotally about the suspended axle  34 , but is also capable of moving up and down inside the opposing grooves  18 .  
         [0018]    Each suspended axle  34  can be supported by a resilient element  36 . The resilient element  36  can be a spiral spring, torque spring, rubber plate spring and the like, and preferably provides a supporting force to the suspended axle  34 . According to the present invention, the resilient element  36  is positioned in the recess  18  so as to apply biased support to the downward movement of the suspended axle  34 . When no force is applied to the key  31 , the resilient element  36  will normally bias the axle  34  upwardly towards the top of the grooves  108 .  
         [0019]    When the user depresses the key  31  at a location away from the suspended axle  34 , the key  31  will turn pivotally about the suspended axle  34 . On the other hand, when the user depresses the key  31  at a location near the suspended axle  34 , then the key  31  will not only turn pivotally about the suspended axle  34 , but will also simultaneously move up or down along the grooves  108 . As a result, the user will not feel the rebounding of the key  31  when force is applied to any part of the key  31 .  
         [0020]    Thus, the present invention omits the necessity of a lengthy extending arm  952 , thereby facilitating use in small-sized input devices. This also enables many add-on peripherals and devices to be easily installed inside the input device  1 . In addition, such add-on devices can be protected from the contamination of exposure to the ambience by the cover  20  as shown in FIG. 3.  
         [0021]    The present invention also overcomes the above-mentioned disadvantages by providing a suspended axle  34  that cushions the rebounding of the keys  31 . The construction of the keys  31 , and its axles  34 , provides numerous benefits in that (i) the construction is simple and inexpensive to manufacture and assemble, and (2) the construction is durable which ensures extended use with minimal deformation.  
         [0022]    While the description above refers to particular embodiments of the present invention, it will be understood that many modifications may be made without departing from the spirit thereof. The accompanying claims are intended to cover such modifications as would fall within the true scope and spirit of the present invention.