Abstract:
A key input device in which an input key is oscillated with respect to an opposing surface facing a bottom portion thereof and in which depression of the opposing surface with the input key at a normal operating point situated above a contact portion of a board causes the input key to tilt in a normal oscillating direction to effect input at the contact portion. Either the bottom portion of the input key or the opposing surface is equipped with guide protrusions arranged symmetrically with respect to an imaginary line extending along the normal oscillating direction of the input key. Depression of the opposing surface with the input key at an erroneous operating point deviated from the normal operating point results in the guide protrusions guiding the input key to tilt in the normal oscillating direction while abutting either the bottom portion of the input key or the opposing surface.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The present invention relates to a key input device equipped with an input key for a pushbutton switch for the input operation of an electronic apparatus, e.g., a portable information terminal, such as a mobile telephone or PDA, an AV apparatus, a car navigation system, and a remote controller for various apparatuses.  
           [0003]    2. Description of the Related Art  
           [0004]    An electronic apparatus is equipped with a number of input keys for executing the functions thereof. Recently, with the advent of multifunction apparatuses, it has now become quite a common practice to provide an apparatus with a key input device in which a single input key is used for a number of different input purposes.  
           [0005]    As an example of an apparatus equipped with such a key input device, FIG. 14 shows a mobile telephone  1 . This mobile telephone  1  is equipped with an input key group  2  with numerals, symbols, patterns, etc. Above the input key group  2 , there is provided an input key  3  of an elliptical flat configuration having upper, lower, right, and left triangular symbols. This input key  3  is generally called a multi-point input key or a multi-directional input key and has a pressurizing operation surface  4  with triangular symbols  4   a . By appropriately depressing one of these triangular symbols  4   a  of the pressurizing operation surface  4 , it is possible to select from items displayed on a display screen  5 , and to move a cursor on the display screen  5  up and down and to the right and left. Of course, under the input key  3  making these operations possible, there are provided, under the triangular symbols  4   a , a printed circuit board (not shown) and contact portions thereof. When one of the triangular symbols  4   a  is depressed, the input key  3  oscillates so as to be tilted (sink) by a predetermined amount to bring the contact portion of the printed circuit board into conduction, whereby the circuit board is closed to realize the operations as described above.  
           [0006]    This input key  3  enabling multiple operations as described above, which advantageously allows an apparatus incorporating it to meet the mutually contradictory requirements of multifunctionality and space saving, is widely used not only in the mobile telephone  1  as shown but also in various apparatuses. However, in actuality, it does not always provide satisfactory results in terms of operability.  
           [0007]    For example, in the above-described input key  3 , as long as each triangular symbol  4   a  is correctly depressed, it is possible to bring the corresponding contact portion of the printed circuit board into conduction. However, if it is depressed at an erroneous operating point deviated therefrom, the contact portions corresponding to adjacent, other triangular symbols  4   a  will also be brought into conduction. Such duplex input will necessitate re-input or lead to malfunction of the mobile telephone  1 .  
           [0008]    This problem in operability is experienced not only with the input key  3  called a multi-point input key having a plurality of operating points (triangular symbols  4   a ), but also with an input key called a seesaw key having only two operating points on a rectangular or elliptical depressing operation surface and an input key called a mono-directional key having only one operating point on a rectangular or elliptical depressing operation surface. That is, there are cases where the contact portion of the printed circuit board is not brought into conduction even when the operator believes that he has depressed the operating point.  
         SUMMARY OF THE INVENTION  
         [0009]    The present invention has been made in view of the above problem in the prior art. It is accordingly an object of the present invention to provide a key input device with superior operability which helps to realize correct input even when an erroneous operating point deviated from the normal operating point has been depressed.  
           [0010]    In order to attain the above-mentioned object, according to the present invention, there is provided a key input device in which an input key can be oscillated with respect to an opposing surface facing a bottom portion thereof and in which depression of the opposing surface with the input key at a normal operating point situated above a contact portion of a board causes the input key to be tilted in a normal oscillating direction to effect input at the contact portion, characterized in that one of the bottom portion of the input key and the opposing surface is equipped with guide protrusions arranged symmetrically with respect to an imaginary line extending along the normal oscillating direction of the input key, and that depression of the opposing surface with the input key at an erroneous operating point deviated from the normal operating point results in the guide protrusions guiding the input key so as to be tilted in the normal oscillating direction while abutting one of the bottom portion of the input key and the opposing surface.  
           [0011]    In accordance with this invention, one of the bottom portion of the input key and the opposing surface is provided with guide protrusions arranged symmetrically with respect to an imaginary line extending along the normal oscillating direction of the input key. Thus, even when the opposing surface is depressed with the input key at an erroneous operating point deviated from the normal operating point, the guide protrusions guide the input key so as to be tilted in the normal oscillating direction while abutting with the bottom portion of the input key or the opposing surface. Accordingly, as in the case in which the input key is depressed as the normal operating point, the input key is guided so as to be tilted in the normal oscillating direction during the oscillation process, whereby input is correctly effected through the contact portion of the circuit board. Thus, it is possible to achieve a satisfactory operability for key input.  
           [0012]    Note that the term “opposing surface” as used herein implies a planar element opposed to the bottom portion of the input key. More specifically, for example, in the case in which the bottom portion of the input key faces a printed circuit board consisting of insulating hard resin with metal circuit wiring, the upper surface thereof constitutes the “opposing surface”. In the case in which the bottom portion of the input key faces a membrane switch, the upper surface of the upper flexible resin film constitutes the “opposing surface”. And, the operability in key input can be made satisfactory as stated above also if the guide protrusions are provided on this opposing surface instead of being provided on the bottom portion of the input key.  
           [0013]    The key input device may have a structure in which the abutting portion of the guide protrusions is formed as a downwardly sloped surface.  
           [0014]    In this invention, the abutting portion of the guide protrusions is formed as a downwardly inclined surface, so that the tilting in the oscillating direction can be effected smoothly, and the operability can be made satisfactory also in terms of operating feel.  
           [0015]    The key input device may have a structure in which a fulcrum protrusion serving as an oscillation fulcrum for the input key is formed on one of the bottom portion of the input key and the opposing surface.  
           [0016]    In this invention, due to the formation of the fulcrum protrusion, it is possible to reliably support the input key to be depressed, making it possible to oscillate it smoothly.  
           [0017]    And, as a form of the key input device equipped with this fulcrum protrusion, the present invention provides a key input device in which the guide protrusions are formed integrally with the fulcrum protrusion.  
           [0018]    In this construction of the invention, in which the guide protrusions are formed integrally with the fulcrum protrusion serving as the oscillation fulcrum for the input key, even if the opposing surface is depressed with the input key at an erroneous operating point deviated from the normal operating point, it is possible, immediately after the oscillation start, to guide the input key so as to be inclined in the normal oscillating direction. Further, since it is possible to quickly transfer the pressurizing force due to the depressing operation from the fulcrum protrusion to the guide protrusions, the durability of the fulcrum protrusion is also improved, thus providing a key input device suitable, in particular, for an apparatus frequently subjected to depressing operation.  
           [0019]    Further, as another form of the key input device equipped with a fulcrum protrusion, the present invention provides a key input device in which the guide protrusions are spaced apart from the fulcrum protrusion.  
           [0020]    This construction of the invention, in which the fulcrum protrusion is spaced part from the guide protrusions, proves particularly effective, for example, in a case in which the requisite oscillation stroke (depression amount) of the input key between the depression start and the conduction of the contact portion is relatively long. That is, when the oscillation stroke of the input key is long, the contact portion can be brought into conduction more correctly if the input key is guided by the guide protrusions so as to be inclined in the normal oscillating direction at a point in time when the input key has been oscillated to some degree since the oscillation start, in other words, at a position nearer to the contact portion.  
           [0021]    The key input device may have a structure in which the input key is a multi-point input key having a plurality of normal operating points that are annularly arranged.  
           [0022]    In accordance with this invention, input can be effected at each operating point even in the case of a multi-point input key in which normal operating points are arranged in an annular fashion.  
           [0023]    The key input device may have a structure in which a guide protrusion is provided in a radial imaginary line extending from a central point of the input key so as to divide into two the interval between adjacent normal operating points.  
           [0024]    In accordance with this invention, the guide protrusions are provided in a radial imaginary line extending from the central point of the input key so as to divide the interval between adjacent normal operating points into two, so that there is no need to form an individual guide protrusion for each normal operating point since one guide protrusion can serve adjacent normal operating points.  
           [0025]    And, an input key to which the above-described key input device is applicable can be formed as a film key sheet in which a key top main body of resin is formed on the back side of a resin film whose front side constitutes the operation surface. As another example of this input key can be formed as a key pad in which a key top main body of hard resin is joined to a key sheet of soft resin. And, as a more specific example of an input key to be realized by the film-integrated-type resin key top and the keypad, it is possible, for example, to provide an input key called a seesaw key with only two operating points on a rectangular or elliptical depressing operation surface, or an input key called a mono-directional key with only one operating point on a rectangular or elliptical depressing operation surface, to which the key input device of the present invention described above is also applicable.  
           [0026]    The above description of this invention should not be construed restrictively. The objectives, advantages, features, and uses of this invention will become more apparent from the following description given with reference to the accompanying drawings. Further, it is to be understood that various modifications, which are made without departing from the gist of this invention fall within the scope of the invention. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0027]    In the accompanying drawings:  
         [0028]    [0028]FIG. 1 is a plan view of a key pad to which a first embodiment of the present invention is applied;  
         [0029]    [0029]FIG. 2 is an enlarged partial view of the back side of the multi-point input key indicated by the alternate long and short dashed lines in FIG. 1;  
         [0030]    [0030]FIG. 3 is an enlarged outside perspective view of an appearance of the oscillation guides (fulcrum protrusion and guide protrusions) shown in FIG. 2;  
         [0031]    [0031]FIGS. 4A through 4D are diagrams illustrating the operation of the multi-point input key, of which FIG. 4A is a plan view of the multi-point input key, FIG. 4B is a sectional view taken along the line SA-SA of FIG. 4A showing the multi-point input key when it is not operated, FIG. 4C is a sectional view equivalent to FIG. 4B showing how the key is tilted when an erroneous operating point P is depressed, and FIG. 4D is a sectional view equivalent to FIG. 4B showing how the key is tilted in the normal oscillating direction;  
         [0032]    [0032]FIG. 5 is an outside perspective view of an appearance of an oscillation guide according to another embodiment of the present invention;  
         [0033]    [0033]FIG. 6 is a bottom view of a multi-point input key according to a second embodiment of the present invention;  
         [0034]    [0034]FIG. 7 is a sectional view taken along the line SB-SB of FIG. 6;  
         [0035]    [0035]FIG. 8 is a plan view of a key pad to which a third embodiment of the present invention is applied;  
         [0036]    [0036]FIG. 9 is a sectional view taken along the line SC-SC of FIG. 8;  
         [0037]    [0037]FIGS. 10A through 10C are diagrams showing a multi-point input key according to a fourth embodiment of the present invention, of which FIG. 10A is a plan view thereof, FIG. 10B is a sectional view taken along the line SD-SD of FIG. 10A, and FIG. 10C is a bottom view thereof;  
         [0038]    [0038]FIG. 11 is an outside perspective view of an appearance of a printed circuit board equipped with an oscillation guide according to still another embodiment of the present invention;  
         [0039]    [0039]FIG. 12 is an exploded perspective view of a membrane switch;  
         [0040]    [0040]FIG. 13 is an outward perspective view showing an example in which the membrane switch of FIG. 12 is equipped with a fulcrum protrusion and guide protrusions; and  
         [0041]    [0041]FIG. 14 is an outward front view of a mobile telephone. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0042]    Embodiments of the present invention will now be described with reference to the drawings. While the embodiments described below are applied to a mobile telephone, they are also applicable to the input key of an input pushbutton switch for other electronic apparatuses, such as a portable information terminal like PDA, an AV apparatus, a car navigation system, and a remote controller for various apparatuses. Further, the portions common to the following embodiments are indicated by the same reference numerals, and a redundant description will be omitted.  
         [0043]    First Embodiment (FIGS.  1  Through  5 )  
         [0044]    [0044]FIG. 1 shows a film key sheet  10  which can be mounted to the above-described mobile telephone  1 . An input key group  11  and a multi-point input key  12  are formed on this film key sheet  10 . The key input device of the present invention is applied to the multi-point input key  12 . The method of manufacturing this film key sheet  10  will be schematically described. First, a protrusion of a configuration corresponding to the input key group  11  and the multi-point input key  12  is formed by performing drawing on a resin film with a molding die. Next, this resin film is placed in an injection molding die, and liquid resin obtained by melting a thermoplastic resin etc. is poured into the inner space of each protrusion and is cured, whereby a key top main body integrated with the resin film is formed. Thus, the multi-point input key  12  is formed as a film-integrated-type resin key top in which a key top main body  14  (See FIG. 2) is formed on the back side of a flexible resin film  13 .  
         [0045]    The multi-point input key  12  has a depressing operation surface  15  with upper, lower, right, and left triangular symbols  16   a ,  16   b ,  16   c , and  16   d  serving as the “normal operating points.” These triangular symbols  16   a  through  16   d  are formed by printing on the resin film. The figures and symbols of the input key group  11  are also formed by printing on the resin film.  
         [0046]    As shown in FIGS. 2 and 4, on the bottom portion  14   a  of the key top main body  14  (the multi-point input key  12 ), there are formed downwardly directed push members  17   a ,  17   b ,  17   c , and  17   d  in correspondence with the triangular symbols  16   a  through  16   d . Further, as shown in FIGS. 2 and 3, substantially at the center of the bottom portion  14   a  corresponding to the center of the depressing operation surface  15 , there is formed an X-shaped, downwardly protruding oscillation guide  18 . This oscillation guide  18  constitutes the main feature of this embodiment. Its most protrusive, central portion is formed as a fulcrum protrusion  19  oscillatably supporting the multi-point input key  12 , with the ridge portions radially extending from the fulcrum protrusion  19  constituting guide protrusions  20   a  through  20   d . In this way, the fulcrum protrusion  19  and the guide protrusions  20   a  through  20   d  are integrated as the oscillation guide  18 , so that, even if an erroneous operating point deviated from the normal operating point is depressed, it is possible for the multi-point input key  12  to be guided so as to be tilted in the normal oscillating direction in the same manner as in the case in which depression is effected at the normal operating points ( 16   a  through  16   d ). Further, since the pressurizing force applied at the time of depressing operation can be transferred from the fulcrum protrusion  19  to the guide protrusions  20   a  through  20   d , the durability of the fulcrum protrusion  19  is also improved, thus providing a key input device particularly suitable for the mobile telephone  1 , on which depressing operation is frequently conducted.  
         [0047]    As shown in FIG. 3, the guide protrusions  20   a  through  20   d  are formed as gently curved slopes extending from the base end on the fulcrum protrusion  19  side in contact with the printed circuit board to their respective distal ends, making it possible to effect the tilting of the multi-point input key  12  smoothly to thereby achieve an improvement also in terms of operating feel. Further, the guide protrusions  20   a  through  20   d  have the same longitudinal length, and exhibit the same amount of protrusion from the bottom surface  14   a  at each longitudinal position thereof. When the opposing surface facing the guide protrusions  20   a  through  20   d  (which, in this embodiment, is the surface of the printed circuit board) exhibits differences in height, it is possible to impart differences in protrusion amount to the guide protrusions  20   a  through  20   d  in correspondence therewith. And, when the multi-point input key  12  is depressed at an erroneous operating point, the longitudinally extending edge portions  20   e  of the respective guide protrusions  20   a  through  20   d  come into contact with the printed circuit board, causing the multi-point input key  12  to be guided so as to be inclined in the normal oscillating direction using the edge portions  20   e  as fulcrums.  
         [0048]    As shown in FIG. 2, the adjacent guide protrusions  20   a  through  20   d  are arranged alternately with the normal oscillating directions  21   a ,  21   b ,  21   c , and  21   d , in one of which the multi-point input key  12  is tilted when it is depressed right on the corresponding one of the triangular symbols  16   a  through  16   d  indicating the normal operating points. The normal oscillating directions  21   a  through  21   d  are indicated by imaginary lines connecting the central point Pc of the fulcrum protrusion  19  with the centers of triangular symbols  16   a  through  16   d  or the center of the push members  17   a  through  17   d . Further, as shown in FIG. 4A, the guide protrusions  20   a  through  20   d  are formed along imaginary radial lines  21   e  and  21   f  extending right between the adjacent ones of the triangular symbols  16   a  through  16   d  or of the push members  17   a  through  17   d . Thus, if, for example, an erroneous operating point deviated from the normal operating point indicated by the triangular symbol  16   a  is depressed, the guide protrusions  20   d  and  20   a  function so as to cause the multi-point input key  12  to be tilted in the normal oscillating direction  21   a . Similarly, for the triangular symbols  16   b ,  16   c , and  16   d , the guide protrusions  20   a  and  20   b , the guide protrusions  20   b  and  20   c , and the guide protrusions  20   c  and  20   d  perform the same function, respectively.  
         [0049]    Next, an example of the operation of the multi-point input key  12 , constructed above, will be illustrated. Under the push members  17   a  through  17   d  formed under the triangular symbols  16   a  through  16   d  of the multi-point input key  12 , there are respectively provided on the printed circuit board  22  contact portions  22   a  through  22   d  composed of metal disc springs and board circuits. While, by way of example, the case in which input is effected by depressing the triangular symbol  16   c  will be described with reference to FIGS. 4A through 4D, the manner of operation to be described also applies to the cases in which input is effected by depressing one of the other triangular symbols  16   a ,  16   b , and  16   d.    
         [0050]    When the multi-point input key is depressed from right above the triangular symbol  16   c , input can be effected correctly through the contact portion  22   c  of the printed circuit board  22 , whereas when a pressurizing force Fm is applied to an erroneous operating point Pm deviated from the normal operating point indicated by the triangular symbol  16   c  (FIGS. 4A and 4B), the multi-point input key  12  will make an attempt to incline in an oscillating direction  21   m  deviated from the normal oscillating direction  21   c , through the fulcrum protrusion  19  of the oscillating guide  18  in contact with the printed circuit board  22 . However, in this inclining process, the edge portion  20   e  of the guide protrusion  20   c  opposed to the push member  17   c  comes into contact with the printed circuit board  22 , so that the multi-point input key  12  is oscillated so as to be tilted inwardly from the erroneous oscillating direction  21   m  toward the normal oscillating direction  21   c  using the edge portion  20   e  as a fulcrum. And, as shown in FIGS. 4C and 4D, as a result of this oscillation, both the guide protrusions  20   b  and  20   c  eventually come into contact with the printed circuit board  22 . Thus, even if the erroneous operating point Pm thereon is depressed, the multi-point input key  12  is tilted in the normal oscillating direction  21   c . Thus, there is no fear of input being effected simultaneously through the adjacent contact portions  22   c  and  22   d  when input ought to be effected solely through the contact portion  22   c , or of an input error occurring at the contact portion  22   c.    
         [0051]    What has been described above is not restricted to the erroneous operating point Pm. Depressing any other point in the sector-shaped area R surrounded by the alternate long and short dashed lines inclusive of the imaginary lines  21   e  and  21   f  in FIG. 4A, will cause the edge portion  20   e  of the guide protrusion  20   b  or the edge portion  20   e  of the guide protrusion  20   c , opposed to the push member  17   c , to come into contact with the printed circuit board  22 , making it always possible for the multi-point input key  12  to be tilted in the normal oscillating direction, using the edge portion as a fulcrum.  
         [0052]    [0052]FIG. 5 shows a possible example of a modification of the oscillation guide  18  of the multi-point input key  12  described above. This oscillation guide  23  also has a fulcrum protrusion  24  and guide protrusions  25   a  through  25   d . The guide protrusions  25   a  through  25   d  have ridge portions  26   a  through  26   d , respectively, which, like the edge portions of the above-described guide protrusions  20   a  through  20   d , are adapted to come into contact with the printed circuit board  22 , enabling the multi-point input key  12  to be tilted in the normal oscillating directions  21   a  through  21   d . Further, the intersection of the ridge portions  26   a  through  26   d  constitutes the fulcrum protrusion  24 , which is in point contact with the printed circuit board  22 , thus oscillatably supporting the multi-point input key  12 . Thus, in this oscillation guide  23  with the fulcrum protrusion  24  and the guide protrusions  25   a  through  25   d , the oscillation of the multi-point input key  12  is further facilitated.  
         [0053]    Second Embodiment (FIGS. 6 and 7)  
         [0054]    [0054]FIGS. 6 and 7 show a second embodiment, which, like the first embodiment, is applied to a multi-point input key  30 . This multi-point input key  30  is also formed as a film-integrated resin key top formed by integrating a flexible resin film  31  with a key top main body  32  of hard resin. A fulcrum protrusion  33  and guide protrusions  34   a  through  34   d  are formed as separate members on a bottom portion  32   a  of the key top main body  32 . This construction makes this multi-point input key different from the multi-point input key  12  of the first embodiment. However, with this construction also, it is possible to achieve the same effect as that of the multi-point input key  12  of the first embodiment. Furthermore, when the requisite oscillation stroke for bringing the contact portions  22   a  through  22   d  of the printed circuit board  22  into conduction is long, this construction proves advantageous. For, the guide protrusions  34   a  through  34   d  are spaced apart from the fulcrum protrusion  33 , so that the multi-point input key  30  is guided so as to be tilted in the normal oscillating directions  21   a  through  21   d  at positions nearer to the contact portions  22   a  through  22   d  of the printed circuit board  22 . Thus, the multi-point input key  30  of this embodiment is advantageous in that it makes it possible to bring the contact portions  22   a  through  22   d  of the printed circuit board  22  into conduction more accurately.  
         [0055]    Third Embodiment (FIGS. 8 and 9)  
         [0056]    [0056]FIG. 8 shows a key pad  40  to which a third embodiment of the present invention is applied. The key pad  40  is equipped with input key groups  41   a  and  41   b . Numeral  42  indicates a multi-point input key according to the third embodiment. Instead of being formed as a film-integrated resin key top as in the embodiments described above, this multi-point input key  42  is composed, as shown in FIG. 9, of a key sheet  43  formed of a rubber-like resilient material such as silicone rubber or thermoplastic elastomer and a separate key top main body  44  of hard resin glued thereto with an adhesive or the like. Thus, the key top main body  44  of the multi-point input key  42  is supported by a one-step higher seat portion  46  through the intermediation of a skirt portion  45  of the key sheet  43 .  
         [0057]    As the above-mentioned structure is employed, in the multi-point input key  42 , only guide protrusions  47   a  through  47   d  and push members  48   a  through  48   d  are formed on a bottom portion  46   a  of the seat portion  46 , and no fulcrum protrusion  19 ,  24 , and  33  as provided in the above-described embodiments is formed. The multi-point input key  42  of this embodiment, in which the key top main body  44  is supported by the seat portion  46  through the intermediation of the skirt portion  45 , is capable of oscillation despite the abolition of the fulcrum protrusion. Further, even if an erroneous operating point is depressed, the multi-point input key  42  can be guided so as to be tilted in the normal oscillating direction ( 21   a  through  21   d ) due to the guide protrusions  47   a  through  47   d  of the seat portion  46 , making it possible to accurately bring the contact portions  22   a  through  22   d  of the printed circuit board  22  into conduction through depression.  
         [0058]    Fourth Embodiment (FIGS. 10A Through 10C)  
         [0059]    [0059]FIGS. 10A through 10C are partial enlarged views of a multi-point input key  50  provided on a key pad. As in the third embodiment, the multi-point input key  50  is formed by joining a key top main body  52  of hard resin to a key sheet  51  of a rubber-like resilient material. As in the first embodiment, an oscillation guide  55  equipped with a fulcrum protrusion  53  and guide protrusions  54   a  through  54   d  protrudes downwards from the key sheet  51 . Numerals  56   a  through  56   d  indicate push members, at the tips of which are provided contact portions  57  with conductive ink applied thereto. Further, the key top main body  52  is of a stick-like configuration, which differs from the flat depressing operation surface  15  of the above-described embodiments. In operating the input key, the key top main body is tilted toward a position directly above each push member  56  (normal operating point) in order that the push member  56  may be moved downwards. Due to its stick-like configuration, the key top main body  52  can be tilted in all directions very easily, so that it is more liable to be tilted in an oscillating direction deviated from the positions directly above the push members  56   a  through  56   d . However, in the multi-point input key  50  of this embodiment, due to the formation of the above-mentioned guide protrusions  54   a  through  54   d , even if operation is performed in such a way as to tilt the key top main body in an erroneous oscillating direction, the key top main body  52  is eventually tilted in the normal oscillating direction, that is, toward the positions directly above the push members  56   a  through  56   d.    
         [0060]    Other Embodiments (FIGS.  11  Through  13 )  
         [0061]    While in the above-described embodiments the linear guide protrusions  20   a  through  20   d ,  25   a  through  25   d ,  34   a  through  34   d ,  47   a  through  47   d , and  54   a  through  54   d  are used, it is not always necessary for the guide protrusions to be of a continuous configuration. For example, it is also possible to form a plurality of columnar members spaced apart from each other, whose height gradually decreases from the oscillation base end toward the oscillation distal end, and use them as the guide protrusions.  
         [0062]    Further, while in the above-described embodiments the multi-point input keys  12 ,  30 ,  42 , and  50  have four normal operating points, the number of normal operating points maybe larger or smaller than four. And, the guide protrusions maybe formed in correspondence with the number of normal operating points. Further, apart from the elliptical one, the depressing operation surface  15  may also be, for example, of a polygonal or circular configuration.  
         [0063]    Further, while in the above-described embodiments the fulcrum protrusions  19 ,  24 ,  33 , and  53  and the guide protrusions  20   a  through  20   d ,  25   a  through  25   d ,  34   a  through  34   d ,  47   a  through  47   d , and  54   a  through  54   d  are formed on the key top main body  14 ,  32  or the key sheet  43 ,  51 , it is also possible to form them on the printed circuit board  22  constituting the “opposing surface” facing the bottom portions  14   a ,  32   a ,  46   a , and  51   a  of the multi-point input keys  12 ,  30 ,  42 , and  50 . FIG. 11 shows an example of such a construction, in which the same oscillation guide  23  formed of thermoplastic resin or the like as shown in FIG. 5 is mounted to a printed circuit board  22  equipped with contact portions  22   a  through  22   d  by means of a fixing means such as adhesive or double-faced tape.  
         [0064]    While in the above-described embodiments the printed circuit board  22  constitutes the “opposing surface” facing the bottom portion  14   a ,  32   a ,  46   a , and  51   a  of the multi-point input key  12 ,  30 ,  42 , and  50 , it is also possible, as shown in FIG. 12, to use a membrane switch  58  instead of the printed circuit board  22 . This membrane switch has a basic structure in which upper and lower films  59  and  60  consisting of flexible resin films are stacked together through the intermediation of a spacer  61  consisting of a double-faced tape or the like. Formed on the upper film  59  are upper contacts  59   a  through  59   d , to which conductive ink or the like is applied to cure thereon. Similarly, lower contacts  60   a  through  60   d  are formed on the lower film  60 . And, when the upper film  59  is pressurized from above the upper contacts  59   a  through  59   d , the upper contacts  59   a  through  59   d  come into contact with the lower contacts  60   a  through  60   d  through holes  61   a  through  61   d  of the spacer  61  to thereby effect input. Thus, the upper contacts  59   a  through  59   d  and the lower contacts  60   a  through  60   d  correspond to the contact portions  22   a  through  22   d  of the printed circuit board  22  of the above embodiments. In the case of this membrane switch  58 , the upper surface of the upper film  59  constitutes the “opposing surface.” And, as shown in FIG. 13, the fulcrum protrusion  62  and guide protrusions  63   a  through  63   d  like those shown in FIG. 6, formed of thermoplastic resin or the like, can be mounted to the upper film  59  of FIG. 12 by a fixing means such as adhesive or double-faced tape.  
         [0065]    In the key input device of the present invention, even if an erroneous operating point deviated from the normal operating point is depressed, the input key can be tilted in the normal oscillating direction for correct input, thus providing a satisfactory operability and making it possible to minimize input errors as less as possible.