Abstract:
An input device for inputting information corresponding to a direction of inclination and an angle of inclination of a movable part into devices such as a computer. The input device includes a substantially spherical part provided at a lower end of said movable part; bearing means which rotatably supports said substantially spherical part of said movable part; a recovery means which rotates said substantially spherical part within said bearing means so as to recover the upright position of the movable part; and inclination detecting means which detects a direction of inclination and an angle of inclination of said movable part.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]    This application is a divisional application of application Ser. No. 09/285,884, filed Apr. 7, 1999, now allowed. 
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    1. Field of the Invention  
           [0003]    The present invention generally relates to an input device used in a computer system, and particularly relates to a pointing device for moving a cursor to a desired position in a display and to an acceleration-measuring apparatus.  
           [0004]    2. Description of the Related Art  
           [0005]    Recently, many computer systems are provided with pointing devices as well as keyboards, so as to provide a data input means of an improved operability.  
           [0006]    Pointing devices such as mouses and digitizers have been commonly used for desktop type computers. However, laptop type or notebook type portable computers require pointing devices which can be used at places where no flat working surface is available.  
           [0007]    Thus, various pointing devices, such as a track-ball type pointing device, which are reduced in size and do not require a flat working surface have been developed.  
           [0008]    [0008]FIG. 1 is a diagram showing an example of a pointing device  100  of the related art.  
           [0009]    As shown in FIG. 1, the pointing device  100  of the related art is provided with a rod  101 . The rod  101  and a supporting frame  102  are connected via a tightly wound coil spring  103 .  
           [0010]    A coordinate detecting part  104  is provided underneath the rod  101  and the supporting frame  102 . The coordinate detecting part  104  includes, for example, a light-emitting element  105  provided at a lower end of the rod  101  and a light-receiving element  106  mounted on a printed-circuit board  107  at a position opposing the light-emitting element  105 .  
           [0011]    The light-receiving element  106  may be a CCD having a number of light-receiving parts arranged in a matrix form. When the rod  101  is pushed in a desired direction with a horizontal force, the coil spring  103  is bent and a shaft center of the operating rod  101  is tilted. Thus, a direction of irradiation of the light-emitting element  105  changes.  
           [0012]    As a result, corresponding to a direction and an angle of inclination, a light beam from the light-emitting element  105  is incident on a specific light-receiving part on the light-receiving element  106 . Then, electric signals are output from the light-receiving parts provided on the light-receiving element  106  at positions corresponding to coordinates of the direction and the angle of inclination of the rod  101 .  
           [0013]    The above-described pointing device  100  of the related art has comparatively large size and weight. Therefore, the pointing device of the related art is cumbersome and difficult to handle with ease. That is to say, there is a problem that the pointing device is not suitable for use by small children.  
           [0014]    Therefore, there is a need for a pointing device which is usable for all ages. Further, there is a need for a pointing device with a reduced size and a good operability.  
         SUMMARY OF THE INVENTION  
         [0015]    Accordingly, it is a general object of the present invention to provide an input device which can satisfy the needs described above.  
           [0016]    It is another and more specific object of the present invention to provide an input device having an operating part which returns to its initial position when released.  
           [0017]    In order to achieve the above objects, an input device includes a substantially spherical part provided at a lower end of said movable part; bearing means which rotatably supports said substantially spherical part of said movable part; a recovery means which rotates said substantially spherical part within said bearing means so as to recover the upright position of the movable part; and inclination detecting means which detects a direction of inclination and an angle of inclination of said movable part.  
           [0018]    The input device described above may be embodied as a pointing device or as an acceleration measuring device. With the structure describe above, it is possible to obtain an input device with a reduced size.  
           [0019]    The recovery means may include a cover having a cylindrical part; a plurality of protrusions protruding outward from said substantially spherical part; a slider slidably provided in said cylindrical part of said cover, a lower end of said slider being supported by said protrusions; and a spring which downwardly spring-biases said slider.  
           [0020]    With the recovery means described above, the input device can be operated with less operational force. Further, it is ensured that the slider and the movable part will recover its original position.  
           [0021]    Other objects and further features of the present invention will be apparent from the following detailed description when read in conjunction with the accompanying drawings. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0022]    [0022]FIG. 1 is a diagram showing a pointing device of the related art.  
         [0023]    [0023]FIG. 2 is an exploded view showing an input device of a first embodiment of the present invention, embodied as a pointing device.  
         [0024]    [0024]FIG. 3 is a cross-sectional diagram showing the pointing device of the first embodiment of the present invention in an upright position.  
         [0025]    [0025]FIG. 4 is a cross-sectional diagram showing the pointing device of the first embodiment of the present invention in a tilted position.  
         [0026]    [0026]FIG. 5 is a diagram showing a first type of a spring used in the present invention which spring has a configuration of a compression coil spring.  
         [0027]    [0027]FIG. 6A is a diagram showing a second type of a spring used in the present invention which spring has a configuration of a tension coil spring.  
         [0028]    [0028]FIG. 6B is a cross-sectional diagram showing a pointing device of the first embodiment of the present invention using the tension coil spring shown in FIG. 6A.  
         [0029]    [0029]FIG. 6C is a graph of a force of a spring (operating force) against an angle of inclination, showing a characteristic of the tension coil spring shown in FIG. 6A.  
         [0030]    [0030]FIG. 7A is a diagram showing a third type of a spring used in the present invention which spring has a configuration of an unevenly pitched coil spring.  
         [0031]    [0031]FIG. 7B is a graph of a force of a spring (operating force) against an angle of inclination, showing a characteristic of the unevenly pitched coil spring shown in FIG. 7A.  
         [0032]    [0032]FIG. 8 is a schematic diagram showing the positioning of the protrusions with respect to the direction of operation, in a case where four protrusions are provided.  
         [0033]    [0033]FIGS. 9A to  9 C are side views showing various types of key tops, a disk type, a stick type and a dome type, respectively, used in the pointing device of the present invention.  
         [0034]    [0034]FIG. 10 is a diagram showing an example of an application of the pointing device of the present invention.  
         [0035]    [0035]FIG. 11 is an exploded view showing an input device of a second embodiment of the present invention, embodied as a pointing device.  
         [0036]    [0036]FIGS. 12A and 12B are cross-sectional diagrams showing the pointing device of the second embodiment of the present invention in an upright position and in a tilted position, respectively.  
         [0037]    [0037]FIG. 13A is a perspective diagram showing a stick assembly together with a housing.  
         [0038]    [0038]FIG. 13B is a top view showing the stick assembly together with the housing.  
         [0039]    [0039]FIG. 13C is a partial side view of the stick assembly and the housing, particularly showing one of the protrusions and its neighboring bosses.  
         [0040]    [0040]FIG. 14 is a perspective diagram of a slider shown together with a holder.  
         [0041]    [0041]FIG. 15 is a block diagram illustrating a signal processing circuit shown in FIG. 11.  
         [0042]    [0042]FIG. 16 is a diagram showing a graph of an output voltage (V) against an angle of inclination of a key-top main body.  
         [0043]    [0043]FIG. 17 is a diagram showing a chart of voltages and output values of a CPU.  
         [0044]    [0044]FIG. 18 is a diagram showing a graph of a velocity of a cursor against an output value of the CPU.  
         [0045]    [0045]FIG. 19 is a diagram showing a pointing device of a first variant of the second embodiment of the present invention.  
         [0046]    [0046]FIG. 20 is a diagram showing a holder and a housing of a pointing device of a second variant of the second embodiment of the present invention.  
         [0047]    [0047]FIG. 21 is a diagram showing a holder and a housing of a pointing device of a third variant of the second embodiment of the present invention.  
         [0048]    [0048]FIG. 22 is a diagram showing a holder and a housing of a pointing device of a fourth variant of the second embodiment of the present invention.  
         [0049]    [0049]FIG. 23 is a diagram showing a holder and a housing of a pointing device of a fifth variant of the second embodiment of the present invention.  
         [0050]    [0050]FIG. 24 is a diagram showing a holder and a housing of a pointing device of a sixth variant of the second embodiment of the present invention.  
         [0051]    [0051]FIG. 25 is a diagram showing a pointing device of a seventh variant of the second embodiment of the present invention.  
         [0052]    [0052]FIG. 26A is a diagram showing a pointing device of an eighth variant of the second embodiment of the present invention and FIG. 26B is a rubber spring used in the pointing device shown in FIG. 26A.  
         [0053]    [0053]FIG. 27 is a diagram showing a key top of a pointing device of a ninth variant of the second embodiment of the present invention.  
         [0054]    [0054]FIGS. 28A and 28B are diagrams showing a stick assembly of a pointing device of a tenth variant of the second embodiment of the present invention.  
         [0055]    [0055]FIG. 29 is an exploded view showing an input device of a third embodiment of the present invention, embodied as an acceleration-measuring apparatus.  
         [0056]    [0056]FIG. 30 is an exploded view showing an acceleration-detecting device shown in FIG. 29.  
         [0057]    [0057]FIGS. 31A and 31B are cross-sectional diagrams showing the acceleration-detecting device of the third embodiment of the present invention in an upright position and in a tilted position, respectively.  
         [0058]    [0058]FIG. 32 is a diagram showing a graph of an acceleration (G) against an angle of inclination of a key-top main body.  
         [0059]    [0059]FIG. 33 is a diagram showing a graph of an acceleration (G) against an output voltage (V).  
         [0060]    [0060]FIG. 34 is a diagram showing an example of application of the acceleration-measuring apparatus of the third embodiment of the present invention.  
         [0061]    [0061]FIG. 35 is a diagram showing a graph of a voltage (V) and an acceleration (G) against time. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0062]    In the following, principles and embodiments of the present invention will be described with reference to the accompanying drawings.  
         [0063]    [0063]FIG. 2 is an exploded view showing an input device of a first embodiment of the present invention, embodied as a pointing device  20 A.  
         [0064]    The pointing device  20 A of the present invention includes a cover  2  and a housing  8  accommodating an operating part  15 , a pressurizing part  16  and a coordinate detecting part  17 . The operating part  15  has a disk-type key top  1   a , a stick  5  and a holder  7 . The stick  5  is provided with a plurality of protrusions  12  arranged in a plane perpendicular to an axis of the stick  5  and passing through the center of inclination of the stick  5 . The pressurizing part  16  includes a slider  4  and a compression coil spring  3   a . The coordinate detecting part  17  includes a (permanent) magnet  6  and a magnetoelectric converting element  9 . All of the above-described components are assembled on a printed-circuit board (PCB)  10  so as to complete a pointing device as shown in FIG. 3.  
         [0065]    The pointing device  20 A is provided with the disk-type key top  1   a  (see FIG. 9A). However, the shape of the key top is not limited to the disk type, but can be a key top of any type, such as a dome-type key top  1   b  (see FIG. 9B) and a stick-type key top  1   c  (see FIG. 9C).  
         [0066]    By using the pointing device  20 A, it is possible to move a cursor to a desired position in a display. Further, as shown in FIG. 2, the pointing device  20 A of the present invention is provided with a plurality of bosses  11  on the housing  8  arranged in a concentric circle having a common center with the operating part  15  and provided between a plurality of protrusions  12 . Thus, it is possible to operate the pointing device in a more stable manner.  
         [0067]    As shown in FIG. 3, the holder  7  has a substantially hemispherical contact surface corresponding to a partly spherical bearing recess of the housing  8 . Referring to FIG. 4, when the key top  1   a  and the stick  5 , serving as a shaft, are tilted, the holder  7  slides on the recess of the housing  8  with the center of the hemispherical contact surface as a fulcrum (center of inclination). In this inclined state, the slider  4  is pushed up by at least one of the protrusions  12  and thus compresses the compression coil spring  3   a.    
         [0068]    The pointing device  20 A of the present invention includes the pressurizing part  16  which exerts a recovery force for the operating part  15  to return to an upright position. Therefore, when the operating part  15  is released, it will automatically return to the initial upright position as shown in FIG. 3. A single compression coil spring  3   a  is sufficient to bring the operating part  15  back into its upright position. FIG. 5 is a diagram of the compression coil spring  3   a  used in the present embodiment.  
         [0069]    Also, a tension coil spring  3   b  shown in FIG. 6A can be used in the pointing device of the present invention. FIG. 6B is a diagram showing a pointing device  20 B using the tension coil springs  3   b . As has been described with the compression coil spring  3   a , when the key top  1   a  and the stick  5 , serving as a shaft, are tilted, the holder  7  slides on the recess of the housing  8  with the center of the hemispherical contact surface as a fulcrum (center of inclination). In this inclined state, the slider  4  is pushed up by at least one of the protrusions  12  and pulls one of the tension coil springs  3   b . As shown in FIG. 6C, an angle of inclination of the operating part  15  is proportional to a force of the spring (operating force). Therefore, the operating force increases as the angle of inclination increases.  
         [0070]    The pointing device  20 B of the present invention includes the pressurizing part  16  which exerts a recovery force for the operating part  15  to return to an upright position. Therefore, when the operating part  15  is released, it will automatically return to the initial upright position shown in FIG. 6B. A plurality of tension coil springs  3   b  bring the operating part  15  back into its upright position.  
         [0071]    [0071]FIG. 7A is a diagram showing an unevenly pitched coil spring  3   c  which can be used in the pointing device of the present invention.  
         [0072]    As has been described with the compression coil spring  3   a , when the key top  1   a  and the stick  5 , serving as a shaft, are tilted, the holder  7  slides on the recess of the housing  8  with the center of the hemispherical contact surface as a fulcrum (center of inclination). In this inclined state, the slider  4  is pushed up by at least one of the protrusions  12  and compresses the unevenly pitched coil spring  3   c . In this case, as indicated in the graph shown in FIG. 7B, a fine operation (fine adjustment) and a coarse operation (coarse adjustment) are possible because of the difference in the strength of force exerted by the unevenly pitched coil spring  3   c.    
         [0073]    The pointing device  20 A of the present invention includes the pressurizing part  16  which exerts a recovery force for the operating part  15  to return to an upright position. Therefore, when the operating part  15  is released, it will automatically return to the initial upright position as shown in FIG. 3. A single unevenly pitched coil spring  3   c  is sufficient to bring the operating part  15  back into its upright position.  
         [0074]    In the pointing device of the present invention using any one of the springs shown in FIGS. 5, 6A and  7 A, the coordinate detecting part  17  detects a direction and an angle of inclination of the operating part  15  by converting the change in magnetic field of the magnet  6  into an electric signal and further processing this electric signal. As a result, it is possible to move a cursor in a desired direction (up, down, right, left and diagonally) in the display.  
         [0075]    In the following, an operation of the pointing device of the present invention for moving the cursor will be described.  
         [0076]    For example, consider a case where four protrusions  12  are provided on the stick  5 , constituting the operating part  15 , at equal intervals. Then, when the operating part  15  is tilted in a direction of one of the protrusions  12 , the slider  4  will be moved by a greater amount, whereas, when the operating part  15  is tilted in the direction between adjacent ones of the protrusions  12 , the slider  4  will be moved by a smaller amount. In other words, a greater operating force is required for tilting the operating part  15  in the direction of one of the protrusions  12 , and a smaller operating force is sufficient for tilting the operating part  15  in the direction between adjacent ones of the protrusions  12 .  
         [0077]    [0077]FIG. 8 is a schematic diagram showing the positioning of the protrusions  12  with respect to the direction of operation, in a case where four protrusions are provided. In FIG. 8, four directions between adjacent protrusions  12 , each of which directions requiring a smaller operating force, are arranged as up, down, right and left directions of the movement of the cursor, respectively. Therefore, since the direction of movement of the cursor can be sensed by hand according to the difference between the greater force and the smaller force, it is possible to realize an improved operability. Also, the number of protrusions  12  provided on the pointing device of the present invention is not limited to four or eight, but can be any number convenient for the operator.  
         [0078]    [0078]FIG. 10 is a diagram showing an example of an application of the pointing device of the present invention. The pointing device of the present invention is incorporated in a cordless remote control unit  21  for moving a cursor in a desired direction (up, down, right, left and diagonally) in the display. Also, an application of the pointing device of the present invention is not limited to a cordless remote control unit, but can also be applied to a remote control unit of a wired type or a built-in type mounted inside a computer.  
         [0079]    [0079]FIGS. 11, 12A and  12 B are diagrams showing an input device of a second embodiment of the present invention, embodied as a pointing device  120 A. In any of the following figures, components similar to the components shown in FIGS. 2 and 3 are indicated by the same reference numerals accompanied by a suffix. In the figures, an X-axis and a Y-axis are lying in a plane of an upper surface of a printed-circuit board  10 A and are mutually perpendicular. A Z-axis passes through a cross-point OA of the X- and Y-axes in a direction perpendicular to the plane of the upper surface of the printed-circuit board  10 A. An upward direction is shown by a reference Z 1  and a downward direction is shown by a reference Z 2 .  
         [0080]    As shown in FIGS. 11 and 12A, the pointing device  120 A includes a pointing device main-body assembly  121 A, the printed-circuit board  10 A and a signal processing circuit  127 A. Four magnetoelectric converting elements  9 AX 1 ,  9 AX 2 ,  9 AY 1  and  9 AY 2  are mounted on the printed-circuit board  10 A. The signal processing circuit  127 A processes the signals from the magnetoeletric converting elements  9 AX 1 ,  9 AX 2 ,  9 AY 1  and  9 AY 2  and outputs predetermined signals.  
         [0081]    As will be described later, the pointing device main-body assembly  121 A is assembled independently from the printed-circuit board  10 A. The pointing device main-body assembly  121 A is mounted on the printed-circuit board  10 A so as to cover the magnetoeletric converting elements  9 AX 1 ,  9 AX 2 ,  9 AY 1  and  9 AY 2  and in such a manner that a disk-type key top  1 A is protruded upward from a box-like outer case  122 A.  
         [0082]    First of all, the pointing device main-body assembly  121 A will be described. The pointing device main-body assembly  121 A includes an operating part  15 A and a pressurizing part  16 A, which are accommodated in a housing  8 A and covered by a cover  2 A.  
         [0083]    The pointing device main-body assembly  121 A is assembled in the following manner. First, a stick assembly  123 A is placed on the housing  8 A. Then, a slider  4 A is fitted on the stick assembly  123 A. Further, a single compression coil spring  3 Aa is mounted on the slider  4 A. The compression coil spring  3 Aa is covered by the cover  2 A, which is screwed onto the housing  8 A by means of screws  125 A. Then, the key top  1 A is fixed on a stick part  124 Aa protruding upward from the cover  2 A.  
         [0084]    The operating part  15 A includes the stick assembly  123 A and the key top  1 A fixed at the top end of the stick assembly  123 A.  
         [0085]    As shown in FIG. 11, the stick assembly  123 A includes a stick  124 A, a disk-shaped magnet  6 A magnetized in its thickness direction, and a hemispherical holder  7 A. The magnet  6 A is accommodated in the holder  7 A in a horizontal manner with its center lying on an axis (Z-axis) of the stick assembly  123 A. The stick  124 A includes the stick part  124 Aa and a hemispherical part  124 Ab provided at a lower end of the stick part  124 Aa. The hemispherical part  124 Ab is provided with eight protrusions  12 A provided radially at equal angular intervals in a plane perpendicular to the Z-axis.  
         [0086]    As shown in FIGS. 12A and 12B, the holder  7 A is fixed at the lower end of the stick  124 A, so that a spherical part  123 Aa is provided which is formed by the holder  7 A and the hemispherical part  124 Ab. The center of the spherical part  123 Aa is indicated by a reference OA 1 . In other words, the spherical part  123 Aa is provided at the lower end of the stick assembly  123 A. The protrusions  12 A are positioned in a plane lying through the center OA 1  in a direction perpendicular to the Z-axis. Also, the holder  7 A may take a form of a polyhedron which has a substantially hemispherical shape. Similarly, the spherical part  123 Aa may take a form of a polyhedron which has a substantially hemispherical shape.  
         [0087]    The key top  1 A includes a key-top main body  1 Aa and a hemispherical dome part  1 Ab provided at a lower end of the key-top main body  1 Aa. The key-top main body  1 Aa is configured as a disk having a size corresponding to a fingertip of the user and its top surface is provided with a projected part  1 Aa 1  so as to prevent a slippage of the finger tip. The dome part  1 Ab has a size sufficient for covering a cylindrical part  2 Aa of the cover  2 A. At the lower end of the key-top main body  1 Aa, a fitting recess  1 Ac having a rectangular opening is provided, which fitting recess  1 Ac projects into the dome part  1 Ab. The key top  1 A is secured at the top end of the stick  124 A with the fitting recess  1 Ac being fitted with a columnar part  124 Aa 1  at an upper end of the stick part  124 Aa protruding upward from the cylindrical part  2 Aa of the cover  2 A.  
         [0088]    As shown in FIG. 13A, the housing  8 A is provided with a receiving seat  8 Aa of a concave shape and eight bosses  11 A. The bosses  11 A are plate-like and are provided at equal angular intervals along the periphery of the receiving seat  8 Aa. The housing  8 A is made of an elastomeric material. Thus, the bosses  11  are elastic and are capable of being easily flexed in a peripheral direction of the receiving seat  8 Aa.  
         [0089]    The stick assembly  123 A is supported by the receiving seat  8 Aa in such a manner that the holder  7 A constituting a lower part of the spherical part  123 Aa is placed on the receiving seat  8 Aa with the surface of the holder  7 A being greased. The cover  2 A has a rim  2 Ac, which is provided so as to oppose the hemispherical part  124 Ab constituting an upper part of the spherical part  123 Aa. The rim  2 Ac and the hemispherical part  124 Ab are either mutually in contact or separated with a small gap. The rim  2 Ac is provided at a position closer to the center compared to the position of a flange  2 Ab. With the spherical part  123 Aa being supported in a rotatable manner by the receiving seat  8 Aa and the rim  2 Ac, the stick assembly  123 A may be inclined but is not movable as a unit in the X, Y and Z-directions.  
         [0090]    The receiving seat  8 Aa and the rim  2 Ac constitute a bearing part  126 A of the spherical part  123 Aa. The spherical part  123 Aa is rotatable inside the bearing part  126 A. As shown in FIG. 12A, the center OA 1  of the spherical part  123 Aa corresponds to the center OA 2  of the receiving seat  8 Aa. Also shown in FIG. 13B, each protrusion  12 A is positioned between neighboring bosses  11 A.  
         [0091]    [0091]FIG. 13C is a partial side view of the stick assembly and the housing, particularly showing one of the protrusions and its neighboring bosses. As shown in the figure, an upper surface  12 Aa of the protrusion  12 A is at a level slightly above a tip surface  11 Aa of the boss  11 A.  
         [0092]    When the stick assembly  123 A is pulled in the Z 1 -direction, the rim  2 Ac of the cover  2 A will receive the surface of the hemispherical part  124 Ab. Thus, the stick assembly  123 A is prevented from being expelled out of the cover  2 A.  
         [0093]    In the following, the pressurizing part  16 A including the slider  4 A and the compression coil spring  3 Aa will be described.  
         [0094]    As shown in FIGS. 12A and 14, the slider  4 A has a substantially cylindrical shape. The slider  4 A includes a compression-coil-spring accommodation part  4 Aa provided at an outer part and having an annular recessed shape, the flange  4 Ab provided on the upper surface and having an annular shape and a plurality of ribs  4 Ac provided on the peripheral surface. Each of the ribs  4 Ac extends in a direction parallel to an axis  4 AZ of the slider  4 A.  
         [0095]    The compression coil spring  3 Aa is mounted on the slider  4 A with its lower part being fitted into the compression-coil-spring accommodation part  4 Aa of the slider  4 A. The upper part of the compression coil spring  3 Aa is protruded upwards from the slider  4 A. Alternatively, the compression coil spring  3 Aa may be replaced with the unevenly pitched coil spring  3   c  shown in FIG. 7A.  
         [0096]    As shown in FIG. 12A, the slider  4 A is fitted with the hemispherical part  124 Ab of the stick assembly  123 A. Also, the slider  4 A is fitted outside the eight bosses  11 A. The annular flange  4 Ab of the slider  4 A is in touch with the upper surfaces of the eight radial protrusions  12 .  
         [0097]    The slider  4 A is fitted in the cylindrical part  2 Aa of the cover  2 A so as to be slidable in the Z 1 -Z 2  directions. The cover  2 A is provided with the annular flange  2 Ab protruding inward from the upper end of the cylindrical part  2 Aa. The upper end of the compression coil spring  3 Aa abuts the backside of the annular flange  2 Ab of the cover  2 A. The compression coil spring  3 Aa is in a slightly compressed state. The slider  4 A is held slightly above an upper surface of the housing  8 A.  
         [0098]    On the backside of the housing  8 A, there are recesses  8 Ab for accommodating the electromagnetic converting elements  9 AX 1 ,  9 AX 2 ,  9 AY 1 , and  9 AY 2 .  
         [0099]    The structure of the pointing device main-body assembly  121 A should be clear from the above descriptions.  
         [0100]    The printed-circuit board  10 A is provided with the electromagnetic converting elements  9 AX 1  and  9 AX 2 , which are provided along the X-axis at symmetrically opposite positions about the point OA. Similarly, the electromagnetic converting elements  9 AY 1  and  9 AY 2  are provided along the Y-axis at symmetrically opposite positions about the point OA.  
         [0101]    The pointing device  120 A is completed in the following manner. As shown in FIG. 12A, the pointing device main-body assembly  121 A is mounted on the PCB (printed-circuit board)  10 A such that the electromagnetic converting elements  9 AX 1 ,  9 AX 2 ,  9 AY 1  and  9 AY 2  are accommodated in the recesses  8 Ab. Further, the box-like outer case  122 A is mounted so as to cover the pointing device main-body assembly  121 A.  
         [0102]    The pointing device  120 A has the box-like outer case  122 A provided with an opening  122 Aa which fits with the dome part  1 Ab. The key-top main body  1 Aa protrudes upward from the outer case  122 A. The opening  122 Aa of the outer case  122 A is provided with a rim  122 Ab which covers the peripheral region of the dome part  1 Ab.  
         [0103]    The above-described pointing device main-body assembly  121 A is assembled independently of the printed-circuit board  10 A. The pointing device  120 A is completed by mounting the pointing device main-body assembly  121 A onto the printed-circuit board  10 A. Thus, the pointing device  120 A is manufactured with an improved efficiency compared to a method of manufacturing a pointing device in which components such as the stick assembly  123 A and sliders  4 A are assembled onto the printed-circuit board  10 A.  
         [0104]    When the pointing device  120 A is completed and the key-top main body  1 Aa is not being operated, the operating part  15 A is in an upright position. In the upright position, the compression coil spring  3 Aa exerts a spring-force, which presses the slider  4 A in a downward direction. The annular flange  2 Ab presses the eight protrusions  12 A equally in a downward direction. The stick assembly  123 A is in a vertical position with the key top  1 A being placed at the top.  
         [0105]    The magnet  6 A in the stick assembly  123 A is positioned directly above the point OA of the printed-circuit board  10 A, so that each of the magnetoelectric converting elements  9 AX 1 ,  9 AX 2 ,  9 AY 1  and  9 AY 2  is subjected to a magnetic field of equal strength. As will be described later, an output value of the signal processing circuit  127 A is 128 counts.  
         [0106]    As shown in FIG. 12B, the stick assembly  123 A can be inclined so that the slider  4 A is upwardly displaced while compressing the compressing coil spring  3 Aa. The direction of inclination can be any direction in the X-Y plane. The stick assembly  123 A is tilted so as to pivot about the point OA 1  (OA 2 ), so that the spherical part  123 Aa is pivoted about the point OA 1  (OA 2 ) in the bearing part  126 A and the hemispherical holder  7 A slides in the receiving seat  8 Aa. The stick assembly  123 A may be tilted until the protrusions  12 A come in contact with the rim  2 Ac of the cover  2 A.  
         [0107]    As shown in FIG. 12A, the center of pivotal movement of the stick assembly  123 A is not on the lower end surface of the stick assembly  123 A but is at a position above the lower end surface by an amount a. Therefore, a range of displacement of the key-top main body  1 Aa (range of operation) for tilting the stick assembly  123 A through a maximum predetermined angle will be smaller compared to a structure in which the stick assembly is tilted about its lower end which is in contact with the receiving seat. Thus, the pointing device  120 A has a reduced size.  
         [0108]    As shown in FIG. 12B, the pointing device  120 A is operated by a user in such a manner that the user&#39;s fingertip  149  is placed on the key-top main body  1 Aa so as to tilt the key top  1 A in a desired direction. The stick assembly  123 A may be tilted in any direction in the following manner. The spherical part  123 Aa is pivoted about the point OA 1  (OA 2 ) inside the bearing part  126 A and one or two of the eight protrusions  12 A push up the annular flange  2 Ab. The slider  4 A is displaced upwardly while compressing the compression coil spring  3 Aa.  
         [0109]    The hemispherical holder  7 A is pressed against the receiving seat  8 Aa with a spring force exerted by the compression coil spring  3 Aa, and slides in the receiving seat  8 Aa. The hemispherical holder  7 A is greased so that the holder  7 A slides smoothly in the receiving seat  8 Aa.  
         [0110]    As shown in FIG. 12A, the magnet  6 A is positioned slightly below the point OA 1 . Therefore, as shown in FIG. 12B, the magnet  6 A is displaced along an arc having a center at the point OA 1 . This causes an imbalance of the strength of magnetic field acting on each of the magnetoelectric converting elements  9 A. Thus, the signal processing circuit  127 A generates a signal corresponding to a direction of operation (direction of inclination) and an angle of inclination of the key-top main body  1 Aa.  
         [0111]    When the user releases his fingertip  149  from the key-top main body  1 Aa, the slider  4 A is pressed downward by a spring force of the compression coil spring  3 Aa. Then, the annular flange  2 Ab presses down the protrusions  12 A, which have been displaced in an upward direction, so as to achieve a state in which the eight protrusions  12 A are pressed down in an equal manner. Thus, the stick assembly  123 A and the key top  1 A recover the upright position shown in FIG. 12A.  
         [0112]    Referring to FIG. 13B, the pointing device  120 A will be described with respect to its resistive force, which differs according to the directions of operation. It can be seen from the figure that there is no protrusion provided in a direction opposite to the X 1 -direction. In other words, an extended line of the direction X 1  passes halfway between protrusions  12 A 1 ,  12 A 2 . In FIG. 13B, the protrusion  12 A 1  is provided in a direction opposite to a direction B.  
         [0113]    When the stick assembly  123 A is operated so as to tilt in the B-direction, the protrusion  12 A 1  pushes up the slider  4 A. When the stick assembly  123 A is operated so as to tilt in the X 1 -direction, the protrusions  12 A 1  and  12 A 2  will push up the slider  4 A. Now, the height of a tip of the protrusion  12 A 1  ( 12 A 2 ) will be compared between cases where the stick assembly  123 A is inclined through the same angle but in different directions. The tip of the protrusion  12 A 1  ( 12 A 2 ) will be at a slightly higher level when the stick assembly  123 A is inclined in the B-direction than when inclined in the X 1 -direction. Therefore, when the stick assembly  123 A is to be tilted in the B-direction, a greater operational force is required compared to a case where the stick assembly  123 A is to be inclined in the X 1 -direction. Thus, from such a difference in the operational force, the user can recognize the direction of operation of the pointing device  120 A.  
         [0114]    In FIG. 13B, arrows  151  indicate directions in which less operational force is required and thus operability is improved.  
         [0115]    In the following, advantageous points of the above-described pointing device  120 A and the pointing-device main-body assembly  121 A will be described.  
         [0116]    First, the pointing device  120 A and the pointing-device main body  121 A can be operated with a reduced operational force. As shown in FIG. 14, the slider  4 A and the cylindrical part  2 Aa of the cover  2 A are provided such that the plurality of the ribs  4 Ac on the peripheral surface of the slider  4 A are in contact with the inner surface of the cylindrical part  2 Aa. Thus, the slider  4 A and the cylindrical part  2 Aa of the cover  2 A are in line contact, rather than in surface contact. This reduces the friction caused by the slider  4 A sliding upward inside the cylindrical part  2 Aa of the cover  2 A as compared to a case of surface contact. Thus, the key top  1 A can be operated with less operational force and thus operability is improved.  
         [0117]    Secondly, the key-top main body  1 Aa is prevented from slipping out. As shown in FIGS. 12A and 12B, the rim  122 Ab of the outer case  122 A covers the peripheral part of the dome part  1 Ab. Therefore, even if the key-top main body  1 Aa is pulled upwards with a strong force, the outer case  122 A prevents the key top  1 A from falling off of the stick  124 A.  
         [0118]    Thirdly, the key-top  1 A is prevented from being rotated. As shown in FIGS. 11, 12A,  12 B and  13 A to  13 C, the key-top main body  1 Aa and the stick  124 A are connected by the fitting recess  1 Ac having a rectangular opening and the columnar part  124 Aa 1  being fitted together. Thus, the key top  1 A is prevented from being rotated with respect to the stick  124 A. Also, the protrusions  12 A on the stick assembly  123 A are each positioned between the neighboring bosses  11 A, so that the stick assembly  123 A is prevented from rotating with respect to the housing  8 A.  
         [0119]    Therefore, even if the user attempts to rotate the key top  1 A about the Z-axis, the protrusions  12 A will abut the bosses  11 A, so that the key top  1 A is prevented from being rotated. This structure is particularly useful when the key top  1 A has a given orientation, which may be indicated by indications provided on an upper surface of the key-top main body  1 Aa.  
         [0120]    Fourthly, the key-top main body  1 Aa does not break even if rotated with a strong force. As has been described above, the key top  1 A is prevented from being rotated by means of the protrusions  12 A and the bosses  11 A. However, there may be a case where a greater force is exerted on the key-top main body  1 Aa. Since the boss  11 A is made of an elastomeric material, as shown in FIG. 13C, when the protrusion  12 A presses the upper part of the boss  11 A, the boss  11 A will bend, as shown by a dash-dot line, and then will recover its original shape. Thus, although the protrusion  12 A is displaced beyond the boss  11 A and the key-top main body  1 Aa is rotated by a small amount, it is possible to avoid the breakage of the boss  11 A and the key-top main body  1 Aa.  
         [0121]    Finally, it is possible to prevent any contaminants from entering inside the outer casing  122 A. As shown in FIGS. 12A and 12B, the opening  122 Aa of the outer case  122 A is blocked by the dome part  1 Ab. Thus, the contaminants are prevented from entering inside the outer case  122 A.  
         [0122]    In the following, the signal processing circuit  127 A will be described.  
         [0123]    As shown in FIG. 15, the signal processing circuit  127 A includes two amplifiers  130 ,  131 , an A/D converter  132  and a central processing unit (CPU)  133 . The CPU  133  includes an arithmetic unit  140 , a storage unit  141 , a clock unit  142  and an interface unit  143 .  
         [0124]    The amplifier  130  differentially amplifies output voltages of the two electromagnetic converting elements  9 AX 1 ,  9 AX 2  provided along the X-axis. The amplifier  131  differentially amplifies output voltages of the two electromagnetic converting elements  9 AY 1 ,  9 AY 2  provided along the Y-axis. The amplified voltages are converted at the A/D converter  132  and then applied to the CPU  133 . In the CPU  133 , the converted data is compared with the data in the storage unit  141  in synchronous with the clock. Then the converted data is converted into a computer recognizable form at the interface unit  143  and then is output to a computer.  
         [0125]    [0125]FIG. 16 is a diagram showing a graph of an output voltage (V) differentially amplified at the amplifier  130  against an angle of inclination of the key-top main body  1 Aa, when the key-top main body  1 Aa is inclined in the X-Z plane. As can be seen from the graph, when the angle of inclination is zero, the voltage is b (V). As indicated by a line  1 , the voltage varies linearly with the angle of inclination. In the given example, the voltage a (V) is output when the angle of inclination is −30 degrees and the voltage c (V) is output when the angle of inclination is +30 degrees.  
         [0126]    [0126]FIG. 17 is a diagram showing a chart of a voltage and an output value of the CPU  133 . For instance, output values of the CPU  133  are 1 count, 128 counts and 256 counts at the voltages of a (V), b (V) and c (V), respectively.  
         [0127]    [0127]FIG. 18 is a diagram showing a graph of a velocity of a cursor on the display screen against an output value of the CPU  133 . As can be seen from line  11 , the cursor moves with a velocity A when the output value is 1 count and the cursor does not move when the output value is 128 counts. When the output count is 256 counts, the cursor moves in a velocity having the same magnitude but an opposite direction to that in the case of an output value of 1 count.  
         [0128]    Also, the direction of inclination of the key-top main body  1 Aa is determined at the CPU  133  based on the ratio between an output voltage of the amplifier  130  and an output voltage of the amplifier  131 .  
         [0129]    Thereby, by operating the key-top main body  1 Aa, the cursor on the display screen moves with a velocity having a direction corresponding to an angle of inclination of the key-top main body  1 Aa.  
         [0130]    In the following, variants of the pointing device of the second embodiment of the present invention will be described.  
         [0131]    [0131]FIG. 19 is a diagram showing a pointing device  120 B of a first variant of the second embodiment of the present invention. A key top  1 B has a hemispherical dome part  1 Bb provided with grooves  1 Bb 1  on its inner surface. A cover  2 B is provided with longitudinal ribs  2 Ba 1  on a peripheral surface of a cylindrical part  2 Ba. The grooves  1 Bb 1  and the ribs  2 Ba 1  are provided at 90 degree intervals in a peripheral direction. The key top  1 B is attached to the cover  2 B with the grooves  1 Bb 1  being fitted to the corresponding ones of the ribs  2 Ba 1 . Thus, the key top  1 B is prevented from being rotated with respect to the cover  2 B at four locations corresponding to the grooves  1 Bb 1 .  
         [0132]    [0132]FIG. 20 is a diagram showing a holder and a housing of a pointing device of a second variant of the second embodiment of the present invention. A stick assembly  123 C has a hemispherical holder  7 C provided with cross-shaped ribs  7 C 1 . A housing  8 C has a receiving seat  8 Ca provided with cross-shaped grooves  8 Ca 1  on its concave surface. The holder  7 C is supported by the receiving seat  8 Ca with the ribs  7 C 1  being fitted in the grooves  8 Ca 1 . Thus, the stick assembly  123 C (and thus a key top mounted there on) is prevented from being rotated with respect to the housing  8 C.  
         [0133]    [0133]FIG. 21 is a diagram showing a holder and a housing of a pointing device of a third variant of the second embodiment of the present invention. A housing  8 D has a receiving seat  8 Da provided with an annular raised part  8 Da 1  on its concave surface. A raised part  8 Da 1  has a semicircular cross section. The holder  7 D is supported by the receiving seat  8 Da at the annular raised part  8 Da 1 .  
         [0134]    A stick assembly  123 D is inclined in such a manner that the holder  7 D slides on the annular raised part  8 Da 1 . Therefore, the contact between the holder  7 D and the receiving seat  8 Da will be a line contact which results in less friction compared to a surface contact. Thus, less operational force is required for tilting the key-top main body and the pointing device has an improved operability.  
         [0135]    [0135]FIG. 22 is a diagram showing a holder and a housing of a pointing device of a fourth variant of the second embodiment of the present invention. A housing  8 E has a receiving seat  8 Ea provided with a cross-shaped raised part  8 Ea 1  on its concave surface instead of the annular raised part  8 Da 1  shown in FIG. 21. The raised part  8 Ea 1  has a semicircular cross-section.  
         [0136]    A stick assembly  123 E is inclined in such a manner that a holder  7 E slides on the cross-shaped raised part  8 Ea 1 . The holder  7 D and the receiving seat  8 Da are in line contact which each other. Thus, less operational force is required for tilting the key-top main body and the pointing device has an improved operability.  
         [0137]    [0137]FIG. 23 is a diagram showing a holder and a housing of a pointing device of a fifth variant of the second embodiment of the present invention. A housing  8 F has a receiving seat  8 Fa provided with three hemispherical protruded parts  8 Fa 1  on its concave surface instead of the annular raised part  8 Da 1  shown in FIG. 21. The hemispherical protruded parts  8 Fa 1  are provided at equal intervals in a peripheral direction.  
         [0138]    A stick assembly  123 F is inclined in such a manner that a holder  7 F slides on the protruded parts  8 Fa 1 . The holder  7 F and the receiving seat  8 Fa are in point contact which each other. Thus, less operational force is required for tilting the key-top main body and the pointing device has an improved operability.  
         [0139]    [0139]FIG. 24 is a diagram showing a holder and a housing of a pointing device of a sixth variant of the second embodiment of the present invention. If there is any contaminant between the receiving seat  8 Ga and a holder  7 G, the holder  7 G cannot slide smoothly. This can cause a reduction in an operability of the pointing device.  
         [0140]    In order to obviate such a drawback, a housing  8 G is provided with an opening  8 Ga 1  at the deepest position of the concave surface of the receiving seat  8 Ga. The contaminant having entered on the concave surface of the receiving seat  8 Ga will be gathered into the opening  8 Ga 1  by operations of a stick assembly  123 G. Thus, the contaminant is removed from the concave surface of the receiving seat  8 Ga and the pointing device can maintain its good operability.  
         [0141]    Also, as shown in FIG. 24 in a dash-dot line, grooves  8 Ga 2  may be provided instead of the opening  8 Ga 1 .  
         [0142]    [0142]FIGS. 25 and 26 are diagrams showing seventh and eighth variants of the second embodiment of the present invention in which variants of the compression coil spring  3 Aa are used.  
         [0143]    [0143]FIG. 25 is a diagram showing a pointing device  120 H of a seventh variant of the second embodiment of the present invention. The pointing device  120 H is provided with garter springs  3 H hooked between a slider  4 H and a housing  8 H. The garter spring  3 H is a ring-shaped coil spring and is used in place of the compression coil spring  3 Aa. The slider  4 H is biased in a downward direction with a spring force of the garter springs  3 H.  
         [0144]    [0144]FIG. 26A is a diagram showing a pointing device of an eighth variant of the second embodiment of the present invention and FIG. 26B is a rubber spring used in the pointing device shown in FIG. 26A. The pointing device  120 I is provided with dome-shaped rubber springs  31  between a slider  41  and a flange  21   b  of a cover  21  instead of the compression coil spring  3 Aa. The slider  41  is biased in a downward direction with a spring force of the rubber spring  31 . When the key top  11  is operated, the dome-shaped rubber spring  31  is elastically deformed as shown in FIG. 26B, and thus the slider  41  is biased in a downward direction.  
         [0145]    [0145]FIG. 27 is a diagram showing a key top of a pointing device of a ninth variant of the second embodiment of the present invention. A key top  1 J is provided with a stick part  1 Ja protruding upward from a hemispherical dome part  1 Jb. The user operates the key-top  1 J by pinching the stick part  1 Ja with his fingertips.  
         [0146]    [0146]FIGS. 28A and 28B are diagrams showing a stick assembly of a pointing device of a tenth variant of the second embodiment of the present invention. FIG. 28A shows a structure in which three protrusions  12 K are provided at equal angular intervals in radial directions perpendicular to the Z-axis. FIG. 28B shows a structure in which six protrusions  12 L are provided in radial directions at unequal angular intervals.  
         [0147]    Thick arrows  150  indicate directions in which greater operational force is required for tilting the stick assemblies  123 K,  123 L. Thin arrows  151  indicate directions in which less operational force is required for tilting the stick assemblies  123 K,  123 L.  
         [0148]    [0148]FIG. 29 is an exploded view showing an input device of a third embodiment of the present invention, embodied as an acceleration-measuring apparatus  160 . FIG. 30 is an exploded view showing an acceleration-detecting device  161  shown in FIG. 29. FIGS. 31A and 31B are cross-sectional diagrams showing the acceleration-detecting device  161  in an upright position and in a tilted position, respectively.  
         [0149]    [0149]FIG. 29 shows the acceleration-measuring apparatus  160  having a printed-circuit board  10 M provided with the acceleration-detecting device  161 , the CPU  133 , LEDs  162 - 1  to  162 - 3 , an infrared communication unit  163 , an acceleration measuring start switch  164  and a measurement data transfer start switch  165 . Further, key-tops  166  and  167  are mounted on the switches  164  and  165 , respectively, and are accommodated within a lower cover  168  and an upper cover  169 . The lower and upper covers  168  and  169  are fastened by means of screws. A button-type battery  170  is accommodated at the backside of the printed-circuit board  10 M and is covered by a lid  171 .  
         [0150]    Further, the acceleration-measuring apparatus  160  may be attached to a belt  172 . Thus, as shown in FIG. 34, a player  180  of a game may be equipped with the acceleration-measuring apparatus  160  on his wrists  181  and ankles  182 .  
         [0151]    The acceleration-detecting device  161  differs from the pointing-device main-body assembly  121 A of FIG. 11 in that, instead of the key-top  1 A, a disk-shaped weight  173  is provided inside a cup-shaped part  123  Mb at the top end of a stick assembly  123 M. Further, a dome-shaped cover  174  is provided so as to cover the weight  173 . The dome-shaped cover  174  opposes a dome-shaped transparent window  169   a  of the upper cover  169 .  
         [0152]    The stick assembly  123 M is provided with an annular flange  12 M instead of the protrusions  12 A in FIG. 11. The upper surface of the annular flange  12 M receives an annular flange  4 Mb of the slider  4 M. When the stick assembly  123 M is tilted, the annular flange  12 M pushes up the annular flange  4 Mb of the slider  4 M. Therefore, the resistive force exerted on the stick assembly  123 M is equal in all direction. In other word, the acceleration-detecting device  161  does not have a particular orientation. Thus, the acceleration-detecting device  161  is capable of accurately measuring accelerations in any direction in the X-Y plane.  
         [0153]    The housing  8 M does not include bosses equivalent to the bosses  11 A. Therefore, the stick assembly  123 M may be rotated about its axis (Z). However this does not cause any inconvenience. Here, the disk-shaped magnet magnetized in the direction of thickness is provided at a position on the axis (Z-axis) of the stick assembly  123 M. Therefore, even if the stick assembly  123 M is rotated about its axis (Z-axis), there will be no effect in detecting acceleration.  
         [0154]    Apart from the above-described points, the acceleration-detecting device  161  has a similar structure to that of the pointing-device main-body assembly  121 A of FIG. 11. In FIGS. 30, 31A and  31 B, similar components to those shown in FIG. 11 is shown by similar reference numerals and further description is omitted.  
         [0155]    The stick assembly  123 M can be inclined in any direction through  360  degrees (any two dimensional direction in the X-Y plane). Then, the slider  4 M is upwardly displaced while compressing the compressing coil spring  3 Ma. Therefore, when an acceleration acts on the weight  173 , as shown in FIG. 31B, the stick assembly  123 M will be tilted in a direction of the acceleration through an angle corresponding to a magnitude of the acceleration.  
         [0156]    [0156]FIG. 32 is a diagram showing a graph of an acceleration (G) against an angle of inclination of a key-top main body. As indicated by a line III, the angle of inclination of the stick assembly  123 M varies linearly against the acceleration acting on the weight  173 . Since the annular flange  12 M is in contact with the annular flange  4 Mb of the slider  4 M, the angle of inclination of the stick assembly  123 M varies linearly against the acceleration acting on the weight  173  in any two dimensional direction in the X-Y plane. When the acceleration acting on the weight  173  is reduced and finally becomes zero, the stick assembly  123 M recovers its upright position shown in FIG. 31A by the spring force of the compression coil spring  3 Ma.  
         [0157]    The signal processing circuit  127 M is identical to the signal processing circuit  127 A shown in FIG. 15. Here, the CPU  133  executes a process for detecting the acceleration.  
         [0158]    When there is acceleration acting on the acceleration-measuring apparatus  160 , as shown in FIG. 32, the angle of inclination of the stick assembly  123 M varies linearly with the acceleration acting on the weight  173 .  
         [0159]    [0159]FIG. 33 is a diagram showing a graph of an acceleration (G) against an output voltage (V). Now, as shown in FIG. 16, the angle of inclination of the stick assembly  123 M and the output voltages are directly proportional. Therefore, as shown in FIG. 33 with a line IV, accelerations of α,  0 , and β are detected at voltages a, b, and c, respectively.  
         [0160]    [0160]FIG. 34 is a diagram showing an example of an application of the acceleration-measuring apparatus of the third embodiment of the present invention. The player  180  of a game shakes his arms and legs with the acceleration-measuring apparatus  160  on his wrists and ankles. Then, a voltage wave form shown in FIG. 35 with a line V will be output from the amplifiers  130 ,  131  (see FIG. 15) of the signal processing circuits  127 M of the acceleration-measuring apparatus  160 .  
         [0161]    The CPU  133  measures at what speed (slowly or quickly) the player  180  has moved his arms and legs based on the magnitude of the acceleration and the time taken. Time is measured by taking synchronization with the clocks of the clock unit  142 .  
         [0162]    As shown in FIG. 34, when the player  180  moves his arms and legs as if he is a kick-boxing player, a virtual player  191  moves with a movement corresponding to a movement of the player  180 , and attacks a virtual opponent  192 .  
         [0163]    Also, the acceleration-detecting device  161  may be of a structure in which variants shown in FIGS. 20 and 26 are applied.  
         [0164]    Further, the present invention is not limited to these embodiments, but variations and modifications may be made without departing from the scope of the present invention.  
         [0165]    The present application is based on Japanese priority applications No. 10-99517 filed on Apr. 10, 1998, and No. 11-052468 filed on Mar. 1, 1999, the entire contents of which are hereby incorporated by reference.