Abstract:
A coordinates input apparatus for designating a particular set of coordinates in three-dimensional space, the coordinates input apparatus includes a substantially box-like frame, an operating part tiltably positioned within the frame, a printed circuit board supporting the frame, a magnet, a plurality of magnetoelectric transducers and a magnetic plate. The magnet and the plurality of magnetoelectric transducers are fixedly mounted on an upper surface of the printed circuit board opposite the magnetic plate, the magnet is disposed so that one pole faces the magnetic plate, the magnetic plate is disposed on a lower surface of the operating part opposite the magnet and tiltably supported by the frame via the operating part, the plurality of magnetoelectric transducers are disposed around an outer rim of the magnet and output voltage signals indicating voltage values that vary according to a change in distance between the magnetoelectric transducers and the magnetic plate, such that the voltage signals indicate a set of coordinates in three-dimensional space.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an improved coordinates input apparatus, and more particularly, to a pointing apparatus that can be used without the need for special operating space. 
     2. Description of Related Art 
     In recent years, easy-to-operate pointing apparatus have come to be widely used instead of keyboards as an input means for computers and the like. 
     For example, a mouse or a digitizer can be used with desktop computers and the like. 
     However, the laptop and other portable computers that have become popular in recent years are often used outdoors, in vehicles, and so forth, that is, in locations where there is no flat surface on which to rest the computer. As a result, there is often little or no space in which to operate a pointing apparatus such as a mouse or digitizer. Additionally, as portable computers have become more compact the need for the pointing apparatus to become smaller has grown as well. 
     Additionally, cellular telephones have come to be equipped with a pointing apparatus. Given the small size of cell phones, the pointing apparatuses used on these devices are required to be even smaller than those used on portable computers and the like. 
     In response to such requirements, a pointing apparatus that tilts when pressed and the angle of tilt sensed has been suggested as one type of suitable pointing apparatus that is compact and requires very little space to operate. 
     A description of such a conventional compact pointing apparatus will now be given with reference to FIGS. 1,  2 ,  3  and  4 . 
     FIG. 1 is a diagram showing a front cross-sectional view of a conventional pointing apparatus illustrating a state in which the key top operating portion of the apparatus is substantially vertical. FIG. 2 is a diagram showing a front cross-sectional view of a conventional pointing apparatus illustrating a state in which the key top operating portion of the apparatus is tilted. FIG. 3 is a diagram illustrating a spatial relation between a magnet and a magnetoelectric transducer of the pointing apparatus shown in FIGS. 1 and 2. FIG. 4 is a diagram showing a side view of the magnet and magnetoelectric transducer of FIG.  3 . 
     According to the conventional art, a pointing apparatus  1  comprises an operating part  2 , a pressure part  3  and a coordinates sensor  4 . 
     The operating part  2  comprises a key top  2   a , a stick  2   b  fixedly mounted to one end part of the key top  2   a,  and a holder  2   c  composed of two halves that form a sphere when joined together. 
     The pressure part  3  comprises a slider  3   a  movable in a vertical direction along a frame  5  and a coil spring  3   b  that continuously presses the slider  3   a  in a downward direction. 
     The coordinates sensor  4  comprises a magnet  4   a  provided on an interior of the holder  2   c  and a plurality of magnetoelectric transducers  4   b  mounted on a printed circuit board  6  bonded to a bottom surface of the frame  5 , the magnetoelectric transducers  4   b  being recessedly mounted in a bottom surface of the holder  2   c . It should be noted that there are actually four magnetoelectric transducers  4   b - 1  through  4   b - 4  displaced a certain distance from the center line of the magnet  4   a,  as can be seen in FIG.  3 . 
     In the pointing apparatus  1  having the structure described above, pressing and moving the key top  2   a  manually slides the slider  3   a  upward against the spring force of the coil spring  3   b  and, as shown in FIG. 2, the stick  2   b  is tilted in a given direction. At this time, the magnet  4   a  built into the holder  2   c  is tilted with respect to the magnetoelectric transducer  4   b  mounted on the printed circuit board  6 . 
     Then, by releasing the key top  2   a,  the spring force of the compressed coil spring  3   b  returns the key top  2   a  to an original position before it was manipulated, thus returning the positional relation between the magnet  4   a  and the magnetoelectric transducer  4   b  to an initial state as well. 
     A description will now be given of the principle upon which the coordinates detector of the pointing apparatus  1  operates. 
     In a case in which the stick  2   b  is perpendicular to the printed circuit board  6  as shown in FIG. 1, as shown by the solid line in FIG. 4 the magnet  4   a  is separated from the four magnetoelectric transducers  4   b  (shown as  4   b - 1  through  4   b - 4  in FIG. 3) by a certain distance, and accordingly the magnetic field imparted to the magnetoelectric transducers  4   b - 1  through  4   b - 4  is essentially equal, so that for example, if the direction from which the magnetic field is sensed is perpendicular to the printed circuit board  6 , then the sensed magnetic field direction components B 1  through B 4  of the magnetic flux density through the magnetoelectric transducers  4   b - 1  through  4   b - 4  would be substantially equal, and thus the output voltage of the magnetoelectric transducers would also be essentially equal. 
     By contrast, if the stick  2   b  is tilted with respect to the printed circuit board  6  as shown in FIG. 2, then the distance separating the magnet  4   a  from the magneto-electric elements  4   b  changes as indicated by the dashed line in FIG.  4 . In the case of FIG. 4, the magnet  4   a  simultaneously approaches the magnetoelectric transducer  4   b - 1  and moves further away from the magnetoelectric transducer  4   b - 3 , so the sensed magnetic field direction component B 1  increases while the sensed magnetic field direction component B 3  decreases and the output voltages from the magnetoelectric transducers  4   b - 1  and  4   b - 3  change as well, with an angle of inclination θ of the key top  2   a  deduced from a calculation of the difference in output between the magnetoelectric transducers  4   b - 1  and  4   b - 3  and further converted into an X-axis coordinate value for the purpose of moving a cursor on a display (coordinate space). Similarly, by calculating the difference in output voltages between the magnetoelectric transducers  4   b - 2  and  4   b - 4  the angle of inclination θ of the key top  2   a  can be converted in a Y-axis coordinate value. That is, XY coordinate values can be obtained when the stick  2   b  tilts in a given direction based on the direction and angle of that tilt. These XY coordinates are input into a computer and the direction, extent and speed of movement of the pointer or cursor then displayed on the display. 
     However, with the conventional pointing apparatus as described above, efforts to further miniaturize the pointing apparatus such as for example by shrinking the magnet and magnetoelectric transducers, has diminished the strength of the magnetic field generated and has led to a situation in which dimensional tolerances in the magnetoelectric transducers show up as unevenness in the performance of the finished apparatus with increased frequency, which is undesirable. Additionally, other measures to reduce the size of the pointing apparatus such as, for example, reducing the distance between the magnet and the magnetoelectric transducers and reducing the distance between each of the plurality of magnetoelectric transducers, has led to a situation in which the magnet and the magnetoelectric transducers physically interfere with each other, that is, the magnet collides with the magnetoelectric transducer when the magnet is tilted during operation of the pointing apparatus. 
     Accordingly, there are physical limitations to the reduction in the size of the components of the pointing apparatus attendant upon efforts to make personal computers, cell phones and the like more compact. 
     BRIEF SUMMARY OF THE INVENTION 
     Accordingly, it is an object of the present invention to provide an improved and useful coordinates input apparatus in which the above-described disadvantage is eliminated, and more specifically, to provide an improved and useful coordinates input apparatus capable of accommodating further reductions in size. 
     The above-described object of the present invention is achieved by a coordinates input apparatus for designating a particular set of coordinates in three-dimensional space, the coordinates input apparatus comprising: 
     a substantially box-like frame; 
     an operating part tiltably positioned within the frame; 
     a printed circuit board supporting the frame; 
     a magnet; 
     a plurality of magnetoelectric transducers; and 
     a magnetic plate, 
     the magnet and the plurality of magnetoelectric transducers fixedly mounted on an upper surface of the printed circuit board opposite the magnetic plate, the magnet disposed so that one pole faces the magnetic plate, the magnetic plate disposed on a lower surface of the operating part opposite the magnet and tiltably supported by the frame via the operating part, the plurality of magnetoelectric transducers disposed around an outer rim of the magnet and outputting voltage signals indicating voltage values that vary according to a change in distance between the magnetoelectric transducers and the magnetic plate, such that the voltage signals indicate a set of coordinates in three-dimensional space. 
     According to this aspect of the invention, the coordinates input apparatus can be made thinner and more compact than is the case with the conventional art. 
     Other objects, features and advantages of the present invention will become more apparent from the following detailed description when read in conjunction with the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a diagram showing a front cross-sectional view of a conventional pointing apparatus illustrating a state in which the key top operating portion of the apparatus is substantially vertical; 
     FIG. 2 is a diagram showing a front cross-sectional view of a conventional pointing apparatus in order to describe a state in which the key top operating portion of the apparatus is tilted; 
     FIG. 3 is a diagram illustrating a spatial relation between a magnet and a magnetoelectric transducer of the pointing apparatus shown in FIGS. 1 and 2; 
     FIG. 4 is a diagram showing a side view of the magnet and magnetoelectric transducer of FIG. 3; 
     FIG. 5 is a front cross-sectional view of a coordinates input apparatus according to a first embodiment of the present invention; 
     FIG. 6 is a front cross-sectional view of a coordinates input apparatus according to a second embodiment of the present invention; 
     FIG. 7 is a perspective view of a magnetic plate used in the coordinates input apparatus according to a second embodiment of the present invention; 
     FIG. 8 is a front cross-sectional view of a coordinates input apparatus according to a third embodiment of the present invention; 
     FIG. 9 is a front cross-sectional view of a coordinates input apparatus according to a fourth embodiment of the present invention; 
     FIG. 10 is a front cross-sectional view of a coordinates input apparatus according to a fifth embodiment of the present invention; 
     FIG. 11 is a perspective view of a magnetic plate used in the coordinates input apparatus according to a fifth embodiment of the present invention; 
     FIG. 12 is a front cross-sectional view of a coordinates input apparatus according to a sixth embodiment of the present invention; 
     FIG. 13 is a front cross-sectional view of a coordinates input apparatus according to a seventh embodiment of the present invention; 
     FIG. 14 is a front cross-sectional view of a coordinates input apparatus according to an eighth embodiment of the present invention; 
     FIG. 15 is a front cross-sectional view of a coordinates input apparatus according to a ninth embodiment of the present invention; 
     FIG. 16 is a front cross-sectional view of a coordinates input apparatus according to a tenth embodiment of the present invention; 
     FIG. 17 is an exploded perspective view of the coordinates input apparatus according to the tenth embodiment of the present invention; and 
     FIG. 18 is a front cross-sectional view of a coordinates input apparatus according to an eleventh embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     A description will now be given of embodiments of the present invention, with reference to the accompanying drawings. It should be noted that identical or corresponding elements in the embodiments are given identical or corresponding reference numbers in all drawings, with detailed descriptions of such elements given once and thereafter omitted. 
     At the outset, it should be noted that the magnetic plates are yokes made of a flexible magnetic material. 
     Additionally, it should be noted that the sets of coordinates include both two-dimensional (that is, XY coordinates) as well as three-dimensional (XYZ) coordinates. 
     Additionally, it should be noted that the basic operating principles of the coordinates input apparatus according to the present invention are essentially identical to that governing the conventional art as described above, so a detailed description thereof shall be omitted. 
     A description will now be given of a coordinates input apparatus according to a first embodiment of the present invention, with reference to the accompanying drawings. 
     FIG. 5 is a front cross-sectional view of a coordinates input apparatus according to a first embodiment of the present invention. 
     As shown in the diagram, the coordinates input apparatus  10  according to the first embodiment of the present invention comprises a frame  12 , a magnet  14 , four magnetoelectric transducers  16   a,    16   b ,  16   c  and  16   d  ( 16   b  and  16   d  not, however, shown in the diagram; refer instead to magnetoelectric transducers  4   b - 1  through  4   b - 4  shown in FIG.  3 ), and a magnetic plate  18 , hereinafter referred to as a first magnetic plate  18 . 
     The magnet  14  is shaped substantially in the form of a cylinder, and is mounted atop a printed circuit board  20  that also functions as a floor surface of the frame  12 . 
     In this case, the magnet  14  is disposed so that a North magnet pole N faces toward the top of FIG.  5 . 
     The magnetoelectric transducers  16   a ,  16   b ,  16   c  and  16   d  are Hall elements, and are disposed atop the printed circuit board  20  around the periphery of the magnet  14  but at a distance from the periphery of the magnet  14 . 
     The first magnetic plate  18  is formed substantially in the shape of a thin magnetic disc made of a flexible magnetic material, and is disposed opposite and above the magnet  14  and the magnetoelectric transducers  16   a ,  16   b ,  16   c  and  16   d . The first magnetic plate  18  is fixedly attached to a bottom surface of an operating part  22 . The operating part  22  is shaped substantially in the form of a disk, with an outer peripheral rim  22   a  thereof bent downward so as to extend toward the magnetoelectric transducers  16   a ,  16   b ,  16   c  and  16   d  without, however, actually contacting the magnetoelectric transducers  16   a ,  16   b ,  16   c  and  16   d . Additionally, a support  24  that forms a portion of the operating part  22  is fixedly attached to a central portion of the bottom surface of the magnetic plate  18 , a lower edge of the support  24  contacting a top surface of the magnet  14 . The operating part  22  is supported by the support  24  so as to be slidable along the frame  12 , that is, tiltable in any direction. 
     In the coordinates input apparatus  10  having the structure described above, a magnetic flux generated from the magnet  14  is conducted by the first magnetic plate  18  to the magnetoelectric transducers  16   a ,  16   b ,  16   c  and  16   d.    
     Accordingly, by tilting the operating part  22  in a desired direction and placing the magnetic plate  18  in a tilted state so as to specify a set of coordinates, a larger magnetic flux is conducted by one end portion  18   a  of the first magnetic plate  18  approaching the North magnetic pole surface of the magnet  14  to the magnetoelectric transducer  16   a  located beneath the magnetic plate portion  18   a . Conversely, another end portion  18   b  of the magnetic plate  18  that is opposite the end portion  18   a  described above is tilted upward and away from the North magnetic pole surface, so a relatively reduced output is obtained from the magnetoelectric transducer  16   c  located beneath the end portion  18   b  as compared to before the magnetic plate was tilted. By determining the difference in output between the two magnetoelectric transducers  16   a  and  16   c  the angle of inclination θ1 of the magnetic plate  18  can be determined, and from the angle of inclination θ1 the direction, angle and speed of movement of the cursor or pointer can be determined. 
     Compared to the conventional art, the coordinates input apparatus  10  described above, merely by the addition of the first magnetic plate  18  which does however increase the size of the coordinates input apparatus, nevertheless results in a reduction in the overall size and particularly the thickness of the unit in which it is inserted because (1) the magnet  14  and the magnetoelectric transducers  16   a ,  16   b ,  16   c  and  16   d  are provided on the same surface of the printed circuit board  20 , and (2) the magnetic plate  18  itself is thin. 
     Additionally, the coordinates input apparatus  10  described above can utilize compact, inexpensive Hall elements for the magnetoelectric transducers  16   a ,  16   b ,  16   c  and  16   d , thus making it possible to produce a compact coordinates input apparatus at low cost. 
     A description will now be given of a coordinates input apparatus according to a second embodiment of the present invention, with reference to FIGS. 6 and 7. 
     FIG. 6 is a front cross-sectional view of a coordinates input apparatus according to a second embodiment of the present invention. FIG. 7 is a perspective view of a magnetic plate used in the coordinates input apparatus according to a second embodiment of the present invention. 
     As can be seen from the diagrams, the coordinates input apparatus  26  according to the second embodiment of the present invention has essentially the same basic structure as the coordinates input apparatus  10  according to the first embodiment of the present invention as described above. 
     The main difference between the first and second embodiments is that in the latter, the first magnetic plate  28  is provided with four projecting flange portions  28   a,    28   b,    28   c  and  28   d  on a peripheral rim of the first magnetic plate  28  bent at right angles to the plate  28 , the flanges extending toward the magnetoelectric transducers  16   a ,  16   b ,  16   c  and  16   d  without actually contacting the magnetoelectric transducers  16   a ,  16   b ,  16   c  and  16   d.    
     In the coordinates input apparatus  26  having the structure described above, because the four flanges  28   a,    28   b,    28   c  and  28   d  are positioned closer to the magnetoelectric transducers  16   a ,  16   b ,  16   c  and  16   d  than the other parts of the rim of the first magnetic plate  28 , any difference in output is magnified and so it is possible to reduce the size of the magnet  14 . 
     A description will now be given of a coordinates input apparatus according to a third embodiment of the present invention, with reference to FIG.  8 . 
     FIG. 8 is a front cross-sectional view of a coordinates input apparatus according to a third embodiment of the present invention. 
     As can be seen from the diagram, the coordinates input apparatus  30  according to the third embodiment of the present invention has a basic structure that is essentially the same as that of the coordinates input apparatus  26  according to the second embodiment of the present invention as described above. 
     The main difference between the second and third embodiments is that in the latter, a second magnetic plate  32  is provided on a back surface of the printed circuit board  20  mounting the magnetoelectric transducers  16   a ,  16   b ,  16   c  and  16   d  and the magnet  14 . 
     In the coordinates input apparatus  30  having the structure described above, most of the magnetic flux generated between the North and South magnetic poles on the top and bottom of the magnet  14  is enclosed within the projected space between the magnetic plates  28 ,  32  and imparted to the magnetoelectric transducers  16   a ,  16   b ,  16   c  and  16   d , so a smaller magnet  14  can be used to obtain a given output. 
     A description will now be given of a coordinates input apparatus according to a fourth embodiment of the present invention, with reference to FIG.  9 . 
     FIG. 9 is a front cross-sectional view of a coordinates input apparatus according to a fourth embodiment of the present invention. 
     As can be seen from the diagram, the coordinates input apparatus  34  according to the fourth embodiment of the present invention comprises a frame (not, however, shown in the diagram), a magnet  36 , four magnetoelectric transducers (not shown in the diagram), and a first magnetic plate  40 , and therefore has essentially the same basic structural elements as the coordinates input apparatus  10  according to the first embodiment of the present invention as described above. 
     The coordinates input apparatus  34  according to the fourth embodiment differs from the coordinates input apparatus  10  according to the first embodiment insofar as the coordinates input apparatus  34  according to the fourth embodiment has a magnet  36  that is substantially annular in shape. Additionally, in contrast to the coordinates input apparatus  10  according to the first embodiment, in which the four magnetoelectric transducers  16   a ,  16   b ,  16   c  and  16   d  are separated from each other, the four magnetoelectric transducers  16   a ,  16   b ,  16   c  and  16   d  of the coordinates input apparatus  34  are accommodated within a package  38 . Additionally, the magnetic plate  40  is substantially disc-shaped, with an aperture  40   a  located in a center thereof. 
     Additionally, the coordinates input apparatus  34  differs from the coordinates input apparatus  10  in that the package  38  that accommodates the four magnetoelectric transducers  16   a ,  16   b ,  16   c  and  16   d  is located inboard of the magnet  36 , whereas in the coordinates input apparatus  10  the four magnetoelectric transducers  16   a ,  16   b ,  16   c  and  16   d  are located outside the magnet  14 . 
     In the coordinates input apparatus  34  having the structure described above, because the package  38  is positioned inboard of the magnet  36  the coordinates input apparatus  34  as a whole can be made more compact than the conventional unit. 
     A description will now be given of a coordinates input apparatus according to a fifth embodiment of the present invention, with reference to FIGS. 10 and 11. 
     FIG. 10 is a front cross-sectional view of a coordinates input apparatus according to a fifth embodiment of the present invention. FIG. 11 is a perspective view of a magnetic plate used in the coordinates input apparatus according to a fifth embodiment of the present invention. 
     As can be seen from the diagrams, the coordinates input apparatus  42  according to the fifth embodiment of the present invention has a basic structure that is essentially the same as that of the coordinates input apparatus  34  according to the second embodiment of the present invention as described above. 
     However, the coordinates input apparatus  42  according to the fifth embodiment differs from the coordinates input apparatus  34  according to the second embodiment insofar as, in the former, four distinct flanges  44   b - 44   e  bent downward so as to project toward the package  38  without actually contacting the package  38  are formed along the rim of the aperture  44   a  of the disc-shaped magnetic plate  44 . 
     In the coordinates input apparatus  42  having the structure described above, a relatively large differential output signal can be obtained because the flanges  44   b - 44   e  are positioned closer to the package  38  than other parts of the disc-shaped magnetic plate  44 , and thus a smaller magnet  36  can be used to obtain a given output. 
     A description will now be given of a coordinates input apparatus according to a sixth embodiment of the present invention, with reference to FIG.  12 . 
     FIG. 12 is a front cross-sectional view of a coordinates input apparatus according to a sixth embodiment of the present invention. 
     As can be seen from the diagrams, the coordinates input apparatus  46  according to the fifth embodiment of the present invention has a basic structure that is essentially the same as that of the coordinates input apparatus  42  according to the fifth embodiment of the present invention as described above. 
     However, the coordinates input apparatus  46  according to the sixth embodiment differs from the coordinates input apparatus  42  according to the fifth embodiment insofar as, in the former, a second magnetic plate  47  is provided on a back surface of the printed circuit board  20  mounting the package  38  and the magnet  36 . 
     In the coordinates input apparatus  46  having the structure described above, most of the magnetic flux generated from the North and South magnetic poles of the magnet  36  is contained within the projected space between the first and second magnetic bodies  44 ,  47  and imparted to the package  38 , so a smaller magnet  36  can be used to obtain a given output. 
     A description will now be given of a coordinates input apparatus according to a seventh embodiment of the present invention, with reference to FIG.  13 . 
     FIG. 13 is a front cross-sectional view of a coordinates input apparatus according to a seventh embodiment of the present invention. 
     Insofar as the coordinates input apparatus  48  according to the seventh embodiment of the present invention comprises a frame (not shown in the diagram), a magnet  50 , a package  52  accommodating four magnetoelectric transducers (not shown in the diagram) and a second magnetic plate  50 , the coordinates input apparatus  48  according to the seventh embodiment has the same basic structure as that of the coordinates input apparatus  34  according to the fourth embodiment. 
     However, the coordinates input apparatus  48  according to the seventh embodiment differs from the coordinates input apparatus  34  according to the fourth embodiment insofar as, in the former, the magnet  50  is annular in shape and provided on a bottom of a disc-shaped magnetic plate  54  having an aperture  54   a  in the center thereof such that one of the magnetic poles is disposed opposite the printed circuit board  20  mounting the package  52 . It should be noted that the package  52  is positioned within a projected area inboard of the magnet  50 . 
     In the coordinates input apparatus  48  having the structure described above, the magnet  50  can be made thinner than is the case with the conventional coordinates input apparatus which has no disc-shaped magnetic plate  54 . 
     A description will now be given of a coordinates input apparatus according to an eighth embodiment of the present invention, with reference to FIG.  14 . 
     FIG. 14 is a front cross-sectional view of a coordinates input apparatus according to an eighth embodiment of the present invention. 
     As can be seen from the diagram, a coordinates input apparatus  56  according to an eighth embodiment of the present invention has a basic structure that is essentially the same as that of the coordinates input apparatus  48  according to the seventh embodiment of the present invention as described above. 
     However, the coordinates input apparatus  56  according to the eighth embodiment differs from the coordinates input apparatus  48  according to the seventh embodiment insofar as, in contrast to the second magnetic plate  54  of the latter, in the former four distinct flanges  58   b - 58   e  (though only  58   b  and  58   d  are shown in the diagram) bent downward so as to project toward the package  38  without actually contacting the package  52  are formed along the rim of the aperture  58   a  of the second magnetic plate  58 . 
     In the coordinates input apparatus  56  having the structure described above, a relatively large differential output signal can be obtained because the flanges  58   b - 58   e  are positioned closer to the package  52  than other parts of the disc-shaped magnetic plate  44 , and thus a smaller magnet  50  can be used to obtain a given output. 
     A description will now be given of a coordinates input apparatus according to a ninth embodiment of the present invention, with reference to FIG.  15 . 
     FIG. 15 is a front cross-sectional view of a coordinates input apparatus according to a ninth embodiment of the present invention. 
     As can be seen from the diagram, a coordinates input apparatus  60  according to a ninth embodiment of the present invention has a basic structure that is essentially the same as that of the coordinates input apparatus  56  according to the eighth embodiment of the present invention as described above. 
     However, the coordinates input apparatus  60  according to the ninth embodiment differs from the coordinates input apparatus  56  according to the eighth embodiment insofar as the former provides a second magnetic plate  62  on the back surface of the printed circuit board  20  mounting the package  52 . 
     In the coordinates input apparatus  60  having the structure described above, most of the magnetic flux generated from the North and South magnetic poles of the magnet  50  is contained within the projected space between the first and second magnetic plates  58 ,  62  and imparted to the package  52 , so a smaller magnet  50  can be used to obtain a given output. 
     A description will now be given of a coordinates input apparatus according to a tenth embodiment of the present invention, with reference to FIGS. 16 and 17. 
     FIG. 16 is a front cross-sectional view of a coordinates input apparatus according to a tenth embodiment of the present invention. FIG. 17 is an exploded perspective view of a coordinates input apparatus according to a tenth embodiment of the present invention. 
     As shown in the diagrams, a coordinates input apparatus  64  according to the tenth embodiment of the present invention comprises a magnet  66 , four Hall elements as magnetoelectric transducers (not shown in the diagrams) accommodated within a package (an integrated Hall element)  68 , a first magnetic plate  70  and a second magnetic plate  72 . Further, the first magnetic plate  70  is tiltably supported by an elastic supporting member  74  made of an elastomer material, the elastic supporting member  74  also forming a frame that accommodates the magnet  66  and so forth. 
     The magnet  66  is substantially annular in shape, and mounted on the printed circuit board so that the North magnetic pole surface faces upward. The package  68  is mounted on the printed circuit board  20  inboard of the magnet  66 . 
     The second magnetic plate  72  is fixedly mounted on the back of the printed circuit board  20 . 
     The elastic supporting member  74  is a substantially annular member in shape, having a flexible intermediate portion  74   a , an upper edge portion  74   c  and a lower edge portion  74   b  that covers the magnet  66  and a portion of the printed circuit board  74   b , the lower edge portion  74   b  being fixedly mounted on the printed circuit board  20  and the magnet  66 . 
     The first magnetic plate  70  is fixedly mounted on the upper edge  74   c  of the elastic member  74 . The first magnetic plate  70  is substantially disc-shaped, with a cylinder extending perpendicularly downward from a rim of an aperture portion  70   a  in a center of the disc-shaped first magnetic plate  70 . Rim  70   b  is positioned so as to be near the package  68 . 
     The substantially disk-shaped operating part  22  is mounted on the top surface of the first magnetic plate  70  so as to contact a projecting rim portion  22   b.  An outer rim portion  22   a  of the substantially disk-shaped operating part  22  is bent so as to project downward and is fixedly mounted on the upper edge  74   c  of the elastic supporting member  74 . 
     In the coordinates input apparatus  64  having the structure described above, pressing an upper rim of the substantially disk-shaped operating part  22  causes the flexible intermediate portion  74   a  of the elastic supporting member  74  to bend, enabling the substantially disk-shaped operating part  22  to tilt in any direction. Additionally, by releasing the substantially disk-shaped operating part  22 , a restorative spring force of the flexible intermediate portion  74   a  of the elastic supporting member  74  causes the substantially disk-shaped operating part  22  to return to a horizontal position. 
     A more detailed description will now be given of the coordinates input apparatus  64 . 
     The magnet  66  is a ferrite magnet, the first magnetic plate  70  is made of soft iron and has a thickness of approximately 0.5 mm, an outer diameter of 12 mm φ, and an inner diameter of 3 mm φ, the outer peripheral rim  22   a  having a height of 1 mm. The first magnetic plate  70  may be made of a ferromagnetic material such as nickel, permalloy and the like, having a relative permeability of 1000μ. The distance between the North magnetic pole surface of the magnet  66  and the bottom surface of the first magnetic plate  70  is 1 mm. The printed circuit board  20  is 0.6 mm thick. The second magnetic plate  72  is a disc approximately 12 mm in diameter, with a nickel plating formed on the surface of the disc to a depth of approximately 30 μm. 
     In the coordinates input apparatus  64  having the structure described above, tilting an operating part  22  so that a center left edge of an outer peripheral rim  22   a  of the first magnetic plate  70  comes approximately 0.6 mm closer to the North magnetic pole causes the Hall element to read 150 mV 0.1 T/5 V and the output differential between two opposed Hall elements to be approximately 30 mV, a level that approximates the output differential when the operating part  2  of the conventional pointing device  1  is at maximum tilt. Accordingly, the coordinates input apparatus  64  can be comparatively thinner than the conventional pointing device  1  yet still operate with the same degree of sensitivity. 
     A description will now be given of a coordinates input apparatus according to an eleventh embodiment of the present invention, with reference to FIG.  18 . 
     FIG. 18 is a front cross-sectional view of a coordinates input apparatus according to an eleventh embodiment of the present invention. 
     The coordinates input apparatus  78  according to the eleventh embodiment of the present invention comprises a printed circuit board  20 , a package  52 , a magnet  50  and a first magnetic plate  58  like those of the coordinates input apparatus  56  according to the eighth embodiment of the present invention as shown in FIG.  14 . Additionally, the coordinates input apparatus  78  according to the eleventh embodiment also has an operating part  22  and a frame  12  like the coordinates input apparatus  10  according to the first embodiment of the present invention. However, the first magnetic plate  58  is not fixedly attached to the operating part  22 . 
     As shown in the diagram, the coordinates input apparatus  78  is provided with an annular magnet  80  on the back side of the substrate  20 . The magnet  80  is positioned so that the South magnetic pole faces the South magnetic pole of the magnet  50 . 
     By controlling the distance between the magnet  50  and the magnet  80  as appropriate, then in a state in which the coordinates input apparatus  78  is not operating the repellent force arising between the magnet  50  and the magnet  80  causes the magnet  50  to rise, pushing the operating part  22  upward via the second magnetic plate  58  so that the outer peripheral rim  22   a  of the operating part  22  engages the frame  12 . 
     By pressing the rim of the operating part  22  with a force sufficient to overcome the repellent force described above, the operating part  22  can be tilted in any direction. By releasing the operating part  22 , the repellent force arising between the magnet  50  and the magnet  80  returns the operating part  22  to the horizontal position. 
     In the coordinates input apparatus  78  having the structure described above, the repellent force arising between the magnet  50  and the magnet  80  is employed as a retaining means for tiltably holding the first magnetic plate  58  within the frame  12  and the operating part  22 , so the structure of the apparatus is simplified and can also be made more compact. Additionally, it can be appreciated that the unavoidable wear on the elastic supporting member produced by repeated use in a case in which an elastic supporting member is used is eliminated. 
     The above description is provided in order to enable any person skilled in the art to make and use the invention and sets forth the best mode contemplated by the inventors of carrying out the invention. 
     The present invention is not limited to the specifically disclosed embodiments, and variations and modifications may be made without departing from the scope and spirit of the present invention. 
     The present application is based on Japanese Priority Application No. 2000-342411, filed on Nov. 9, 2000, the contents of which are hereby incorporated by reference.