Abstract:
The major characteristic of the present invention lies in the adoption of electromagnetic means to translate the spin of a wheel module into continuous electrical signals. A permanent magnet is incorporated in the wheel module to provide magnetic field. Two sensors tangential to the spinning direction of the permanent magnet are used to detect the variations of the magnetic field from the spin of the wheel module in accordance with the Hall Effect.

Description:
TECHNICAL FIELD OF THE INVENTION 
       [0001]    The present invention generally relates to pointing devices, and more particularly to a scroll wheel device for use in a pointing device to translate the spin of a wheel module into corresponding electrical signals. 
       DESCRIPTION OF THE PRIOR ART 
       [0002]    In addition to the conventional pointing and clicking functions, a recent innovation in computer mice is to integrate a scroll wheel that allows a user to scroll the onscreen image of a document like a Web page or spreadsheet vertically (up/down) and/or horizontally. 
         [0003]    Usually a mechanical switch encoder is adopted to translate the spin of the scroll wheel into signals that a computer can use. The mechanical switch encoder has a number of disadvantages. First, as a mechanical means, the switch encoder may suffer deteriorated contact after a period of usage, thereby limiting its operation life. Secondly, with its inherent limitation, the switch encoder has a limited scrolling resolution and cannot provide continuous scrolling. 
         [0004]    Even though some computer mice adopt optical encoders to obviate some of the shortcomings of the mechanical switch encoder, the optical encoder still suffers some disadvantages. For example, the scrolling resolution is affected by the diameter of the scroll wheel. To achieve high scrolling resolution, a bigger scroll wheel has to be adopted and the optical encoder is therefore not appropriate for a miniature pointing device. If a smaller scroll wheel is used, the scrolling resolution again is limited. 
       SUMMARY OF THE INVENTION 
       [0005]    Accordingly, a novel scroll wheel device is provided herein to obviate the shortcomings of the present invention. 
         [0006]    The major characteristic of the present invention lies in the adoption of electromagnetic means to perform the translation. A permanent magnet is incorporated in a wheel module to provide magnetic field. Two sensors tangential to the spinning direction of the permanent magnet are used to detect the variations of the magnetic field from the spin of the wheel module in accordance with the Hall Effect. 
         [0007]    Compared to conventional mechanical or optical means, the present invention provides a number of advantages. First of all, the scroll wheel device is able to provide analog or continuous electrical signals and therefore is able to achieve significantly greater scrolling resolution and smooth scrolling of the onscreen image. Secondly, the scrolling resolution is not related to the diameter of the wheel module and therefore the scroll wheel device may be integrated into miniature electronic devices. 
         [0008]    The foregoing objectives and summary provide only a brief introduction to the present invention. To fully appreciate these and other objects of the present invention as well as the invention itself, all of which will become apparent to those skilled in the art, the following detailed description of the invention and the claims should be read in conjunction with the accompanying drawings. Throughout the specification and drawings identical reference numerals refer to identical or similar parts. 
         [0009]    Many other advantages and features of the present invention will become manifest to those versed in the art upon making reference to the detailed description and the accompanying sheets of drawings in which a preferred structural embodiment incorporating the principles of the present invention is shown by way of illustrative example. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]      FIG. 1  is a perspective view showing a first embodiment of the present invention installed inside a computer mouse. 
           [0011]      FIG. 2  is a perspective view of the first embodiment of  FIG. 1 . 
           [0012]      FIG. 3  is a perspective exploded view showing the various components of the first embodiment of  FIG. 1 . 
           [0013]      FIG. 4  is a perspective exploded view showing the various components of a second embodiment of the present invention. 
           [0014]      FIG. 5  is a sectional view of the first embodiment of  FIG. 1 . 
           [0015]      FIG. 6  is a profile view of the signal extraction unit of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0016]    The following descriptions are exemplary embodiments only, and are not intended to limit the scope, applicability or configuration of the invention in any way. Rather, the following description provides a convenient illustration for implementing exemplary embodiments of the invention. Various changes to the described embodiments may be made in the function and arrangement of the elements described without departing from the scope of the invention as set forth in the appended claims. 
         [0017]    In the following, a computer mouse is mainly used as an example to explain the embodiment of the present invention. However, the principle of the present invention may be readily applied to various types of other pointing or electronic devices. 
         [0018]      FIG. 1  shows an embodiment of the present invention housed inside a computer mouse  1 , with a top cover of the computer mouse  1  removed to reveal the details inside. As further illustrated in  FIG. 2 , the present embodiment contains a wheel module  2  and a signal extraction unit  3 , integrated to a pedestal  25  to jointly provide the function of a scroll wheel. 
         [0019]    As illustrated in  FIGS. 3 and 5 , the wheel module  2  contains cylindrical main ring  23  having an anti-slippery ring  24  coaxially embedded in the circumference of the main ring  23 . The wheel module  2  further contains cylindrical axle  22  axially threaded in and tightly joined with the main ring  23 . The axle  22  has two tips  222  extended beyond its two end surfaces for an appropriate distance. At a first end of the axle  22 , the end surface is concaved to form a socket (not numbered) and the tip  222  there has a thicker axial base  221  so that a ring-shaped permanent magnet  21  can be tightly fitted on the thicker base  221  and housed in the socket. The wheel module  2  is assembled as such so that, when the main ring  23  is turned, the axle  22  and the magnet  21  are turned synchronously. 
         [0020]    As shown in  FIGS. 2 ,  3 , and  5 , the pedestal  25  is a frame forming a generally rectangular space  251  for housing the wheel module  2  inside. The pedestal  25  therefore surrounds the wheel module  2  diametrically. There are two corresponding holes  252  on the two opposing longer sides (hereinafter, the first and second sides) of the pedestal  25 , respectively, for the accommodation of the tips  222  of the wheel module  2 . As such, the wheel module  2  is rotatably mounted on the pedestal  25  with the permanent magnet  21  adjacent to the first side of the pedestal  25 . On the outer surface of the first side of the pedestal  25 , a rectangular seat  253  is provided to accommodate the approximately rectangular signal extraction unit  3 . Also on the outer surface of the first side of the pedestal  25  is a pair of laterally opposing clasps  2511  to reliably hold the signal extraction unit  3  inside the seat  253 . 
         [0021]    As further shown in  FIG. 6 , the signal extraction unit  3  is mainly a circuit board  31  having two sensors  32  electrically connected to the circuit board  31 . Please note that the two sensors  32  are arranged so that they are tangential to the spinning direction of the permanent magnet  21 . According to the Hall Effect, as the permanent magnet  21  turns, the two sensors  32  are able to pick up the variations of the magnetic field produced by the permanent magnet  21  and then translate to corresponding electrical signals. 
         [0022]      FIG. 4  shows a second embodiment of the present invention to enhance the positioning of the permanent magnet  21 . As illustrated, a cylindrical auxiliary ring  26  is provided so that the axle  22  is first threaded axially into a second end of the auxiliary ring  26  and the combination is then threaded axially into the main ring  23 . To tightly join the axle  22  and the auxiliary ring  26  together, at least a wedge  223  is provided along the circumference of the axle  22  and at least a notch  261  is provided along the circumference of the auxiliary ring  26 , corresponding to the wedge  223 . As such, when the axle  22  is threaded into the auxiliary ring  26 , the wedge  223  is embedded into the corresponding notch  261 . Please note that a first end of the auxiliary ring  26  opposite to the second end has an aperture (not shown) smaller than the diameter of the permanent magnet  21 . As such, the permanent magnet  21  is reliably sandwiched between the axle  22  and the auxiliary ring  26 . 
         [0023]    It will be understood that each of the elements described above, or two or more together may also find a useful application in other types of methods differing from the type described above. 
         [0024]    While certain novel features of this invention have been shown and described and are pointed out in the annexed claim, it is not intended to be limited to the details above, since it will be understood that various omissions, modifications, substitutions and changes in the forms and details of the device illustrated and in its operation can be made by those skilled in the art without departing in any way from the split of the present invention.