Abstract:
A keypad that provides excellent operability even in a virtual keyboard on a touch panel. The keypad comprises a base body  11 , which covers the touch panel, and key tops  12 , which are formed at positions corresponding to sensing areas of the touch panel. Each of the key tops  12  is formed to get in contact with the sensing area corresponding to the key top in question by pushing of the key top.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    The present invention relates to a keypad. 
         [0002]    Presently, mobile computers with wireless LAN are blooming, and many portable devices are used. Among such devices, there is a tablet computer provided with a touch-sensitive liquid crystal display. A tablet computer is not mounted with a keyboard specially as its input unit, and a touch panel integrated with a display can be used to perform input operation. Such a touch panel, which can be operated by directly touching a screen with a finger or the like, has been used frequently in industrial fields such as a Point Of Sale System (POS) and an Automated Teller Machine (ATM) until now. Recently, however, a touch panel is used in a consumer device, and its operability is improved further by employing the “multi-touch” function that sells intuitive operation and allows a touch of two points on the panel at one time. 
         [0003]      FIG. 5  shows an example of such a computer. A tablet computer  90  is general one of a plate shape, comprising a frame part  91  and a touch panel  92 . The touch panel  92  comprises; a screen keyboard display area  92   a  as a virtual keyboard shown on the display; and a text display area  92   b  for displaying text consisting of letters, symbols, and the like (i.e. characters). The screen keyboard area  92   a  is a virtual keyboard showing a key arrangement (for example, the QWERTY arrangement) of an ordinary keyboard, and here comprises a plurality of character display areas  92   c  corresponding to keys respectively. Each character display area is a sensing area that senses contact of or pressing by a fingertip or a pen point. When such contact or pressing is sensed, a character assigned to the display area in question is displayed in the text display area  92   b.    
         [0004]    As such a touch panel, there are various types of touch panels such as: a resistance film type, which responds to pressure by a pen, a finger, or the like; a capacitance type, which senses a change in the capacitance between a fingertip and a conductive film; an electromagnetic induction type, which utilize electromagnetic induction caused by bringing a pen closer; and a built-in optical sensor type, which optically recognizes a movement of a fingertip or a pen. In the types allowing use of a finger tip among these types, i.e. in the resistance film type, the capacitance type and the built-in optical sensor type, a user can use a screen keyboard as illustrated in  FIG. 5  in the same finger position as that in an ordinary keyboard. 
         [0005]    However, as for character input operation, the operability of such a screen keyboard does not come up to an ordinary keyboard yet. This is because the display of a plate shape makes it difficult to input relying on feeling in fingertips. This causes, for example, input failure owing to touching at an inappropriate part in touch-typing or difficulty in confirming the home position. Accordingly, it is difficult to input without an error unless by visual touching or single-finger touching. 
         [0006]    On the other hand, the below-mentioned Patent Document 1 discloses a mobile keyboard. This, however, spoils portability of a mobile computer.
   Patent Document 1; Japanese Unexamined Patent Application Laid-Open No. 2002-73256   
 
         [0008]    Thus, an object of the present invention is to provide a keypad that gives a superior operational feeling even for a two-handed virtual keyboard on a touch panel. 
       SUMMARY OF THE INVENTION 
       [0009]    To solve the above problems, the present invention provides a keypad comprising a base body  11 , which covers a touch panel, and key tops  12 , which are formed at positions corresponding to sensing areas of the touch panel. Each of the key tops  12  is formed to get in contact with the sensing area corresponding to the key top in question by pushing of the key top. 
         [0010]    According to the present invention, it is possible to provide a keypad that gives excellent operability even in a virtual keyboard on a touch panel. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]      FIG. 1  is an explanatory view showing a keypad  1  according to a first embodiment of the present invention; 
           [0012]      FIG. 2  shows  2 ( a ) a traverse cross-section view of the keypad  1  of the first embodiment of the present invention; and  2 ( b ) a perspective view of the keypad  1  of the first embodiment of the present invention; 
           [0013]      FIG. 3  is a cross-section view of the keypad  1  of the first embodiment of the present invention; 
           [0014]      FIG. 4  shows  4 ( a ) a cross-section view of a key top  121  used in a keypad of a modification 1 according to the present invention;  4 ( b ) a cross-section view of a key top  122  used in a keypad of a modification 2 according to the present invention; and  4 ( c ) a cross-section view of a key top  123  used in a keypad of a modification 3 according to the present invention; and 
           [0015]      FIG. 5  is an explanatory view showing a conventional tablet computer  90 . 
       
    
    
     DETAILED DESCRIPTION 
       [0016]    Now, embodiments of the present invention will be described referring to the drawings. 
       First Embodiment 
       [0017]      FIG. 1  is an explanatory view showing a keypad  1  according to a first embodiment of the present invention.  FIG. 2(   a ) is a traverse cross-section view of the keypad  1  of the first embodiment of the present invention. And,  FIG. 2(   b ) is a perspective view of the keypad  1  of the first embodiment of the present invention. 
         [0018]    As shown in  FIG. 1  and  FIGS. 2(   a ) and  2 ( b ), the keypad  1  as an embodiment of the present invention comprises: a base body  11  of a plate shape; and key tops  12  formed respectively to be positioned over and to correspond to character display areas (sensing areas)  92   c.    
         [0019]    The keypad  1  is used in a state that the keypad  1  is detachably overlaid upon a virtual keyboard displayed on a touch panel  92  of an ordinary tablet computer  90 . Here, it is intended that the keypad  1  covers a screen keyboard display area  92   a  and side surfaces of the tablet computer  90 . 
         [0020]    The keypad  1  of this arrangement can be obtained by molding of an elastic material. As an elastic material, may be mentioned, for example, polymer such as rubber, silicone, polyethylene, polyurethane, and elastomer. By using such a material, it is possible to mold a thin and flexible keypad  1  so that the keypad  1  is deformed by pressing with a user&#39;s finger and the original form is restored by releasing the pressure. 
         [0021]    As shown in  FIG. 2(   a ), the base body  11  has tabs  11   a  at both ends. By fixing the tabs  11   a  on the side and back surfaces of the tablet computer  90 , the keypad  1  can be fitted well on the tablet computer  90 . The invention is not limited to this arrangement. It is possible to use a keypad that is wound on the tablet computer. Or, a keypad may be fixed by means of a band, or by using or providing suction cups. 
         [0022]    As shown in  FIG. 2(   b ), each key top  12  has: a hollow edge portion  12   a  that is formed to rise from the base body  11 ; a concave portion  12   b  that is formed within the edge portion and recessed into a dome shape; and a through hole  12   c  that is formed roughly in the center of the concave portion. Here, the edge portion  12   a  is formed to be nearly equal in size to a character display area  92   c . Further, here the key top  12  is held in a state of floating from the character display area  92   c  to avoid contact with the sensing area (See  FIG. 3) . Here, a sponge material may be used on the base body  11  at the portion corresponding to the periphery of each character display area  92   c , or on the contrary may be used in wide contact with each character display area  92   c , so as to avoid false operation caused by an unintended touch or by the weight of the keypad itself. Further, although not shown, it is possible to augment the feeling of the keys by employing a structure that emits a sound due to shape change when a key top  12  changes its shape by depression of the key top  12 . 
         [0023]    Here, the layout of the key tops  12  is of a three-line configuration conforming to the QWERTY layout, i.e. the layout of an ordinary keyboard. However, any layout may be employed. Further, the key tops  12  may have marks  12   d  such as projections to indicate the home position. Further, the key tops  12  or the keypad  1  itself may be formed to be transparent or semitransparent so that a user can see characters corresponding respectively to the keys. Of course it is possible to arrange that a character displayed in a character display area  92   c  can be seen through the through hole  12   c . Or, a character  12   e  may be displayed for example by printing on each key top  12 . In particular, when the keypad  1  is used at a dark place, it is favorable that the keypad  1  or at least the key tops  12  have translucency. 
         [0024]    Hereinafter, specific usage of the above-described keypad  1  will be described.  FIG. 3  is a cross-section of the keypad  1  of the first embodiment of the present invention. 
         [0025]    As shown in  FIG. 3 , a user puts his fingertip  100  in the dome-shaped concave portion  12   b  of a key top  12  positioned over the character display area  92   c  of any character that the user wants to input, and pushes the concave portion  12   b . Then, the key top  12  is deformed, being bent downward (toward the touch panel). In the case where the touch panel  92  is of the capacitance type, contact of the user&#39;s fingertip  100  with the character display area  92   c  through the through hole  12   c  is detected, and the character assigned to the character display area  92   c  is displayed in the text display area  92   b . On the other hand, in the case where the touch panel  92  is of the resistance film type, pressuring of the character display area  92   c  by the bottom of the key top  12  or the user&#39;s fingertip  100  is detected, and the character assigned to the character display area  92   c  is displayed in the text display area  92   b . When the finger is disengaged from the key top  12 , then the key top  12  returns to the original shape. Of course, it is possible to operate a touch panel of another type such as the built-in optical sensor type. 
         [0026]    According to the thus-described shape of key top  12 , a user&#39;s finger is naturally led onto the through hole  12   c  opened over the character display area  92   c  corresponding to the character that the user wants to input, and thus the user can perform input operation (touching) at a right point. Accordingly, it is possible to reduce false operation significantly. Further, the location of each key top  12  (or a character display area  92   c ) can be found through a touch of a fingertip, and therefore touch-typing can be carried out easily too. Further, it is possible to get proper feeling of typing, and thus a good operational feeling and pleasantness are obtained. 
         [0027]    Hereinabove, one embodiment of keypad according to the present invention has been described. The above-described keypad is not restrictive, and many alternatives, modifications and variations are obvious to those skilled in the art. In the following, such variations will be described. 
       [Variation 1] 
       [0028]      FIG. 4(   a ) is a cross-section of a key top  121  formed in a keypad of a variation 1 according to the present invention. In the following description of variations, the same symbols are used to indicate the same components as those in the above embodiment, and thus their detailed description will be omitted. 
         [0029]    Although the key top  121  of this variation has the almost same configuration as that of the key top  12  of the first embodiment, this key top  121  is different from the key top  12  of the first embodiment in that this key top  121  has a convex portion  121   c  toward the touch panel instead of the through hole  12   c . When, in the key top  121  of this arrangement, a user pushes the concave portion  12   b , the convex portion  121   c  presses the character display area  92   c . By detecting this pressuring, input operation is fulfilled. This arrangement is particularly suitable for the case of the resistance film type. 
       [Variation 2] 
       [0030]      FIG. 4(   b ) is a cross-section of a key top  122  formed in a keypad of a variation 2 according to the present invention. 
         [0031]    Although the key top  122  of this variation has the almost same configuration as that of the key top  121  of the variation 1, this key top  122  is different from the key top  121  of the variation 1 in that this key top  122  has a convex portion  122   c  of a conductive material instead of the convex portion  121   c  of the variation 1. When, in the key top  122  of this arrangement, a user pushes the concave portion  12   b , the convex portion  122   c  contacts with the character display area  92   c . By detecting this touch, input operation is fulfilled. This arrangement is suitable for both the capacitance type and the resistance film type of touch panels  92 . The convex portion  122   c  may be formed of a hard material so that a hit sound due to a hit is emitted when the convex portion  122   c  contacts with the character display area  92   c . Even if the whole convex portion  122   c  is not formed of a conductive material, it is sufficient that the surface is coated with a conductive coating material, or includes such material, or is partly attached with such material so that a fingertip  100  connects electrically with the sensing area. 
       [Variation 3] 
       [0032]      FIG. 4(   c ) is a cross-section of a key top  123  formed in a keypad of a variation 3 according to the present invention. 
         [0033]    Although the key top  123  of this variation has the almost same configuration as that of the key top  121  of the variation 1, this key top  123  is different from the key top  121  of the variation 1 in that this key top  123  has a convex portion  123   c  having a reflecting surface instead of the convex portion  121   c  of the variation 1. The key top  123  of this arrangement is particularly suitable for the built-in optical sensor type that has optical sensors embedded in a transistor-shaped surface of a liquid crystal panel. More specifically, when a user pushes the concave portion  12   b , the convex portion  123   c  contacts with the character display area  92   c . By detecting the reflection or shadow of the contact portion, input operation is fulfilled. This reflecting surface can be formed by attaching a reflecting member adapted for an optical sensor, or by painting or printing. Further, the material of the key top  123  may be a transparent material so that it is hard for an optical sensor to sense the key top  123 . Or, to prevent surface reflection, the surface of the key top  123  may be subjected to, for example, grain or hair line finishing in order to scatter or absorb light. Further, judgment of a push of a key is performed by software installed on the tablet computer on the basis of the sensing level of an optical sensor. The threshold of sensing level may be adjusted when the keypad is used. The threshold should be set such that a push of a key top is judged to be a push of a key. 
         [0034]    Thus, the keypad  1  of the present invention can be adapted for various types of sensing techniques. Of course, the touch panel is not limited to the above-described one, and the keypad  1  of the present invention can be applied to any touch panel whose input operation can be performed by contact of a finger or an object. Further, it is possible to use a combination of the characteristics of the above-described embodiments and variations. 
         [0035]    It is not necessary to form a through hole or a convex portion in the key top. In the case of the resistance film type, input operation can be performed sufficiently only if the bottom of the concave portion  12   b  presses the character display area  92   c.    
         [0036]    Further, regardless of the type of virtual screen keyboard, the keypad  1  of the present invention can be easily adapted to any virtual screen keyboard by replacing with the corresponding keypad  1 . 
         [0037]    It is further possible to make each sensing area on the touch panel side smaller so that pressing through the through hole or by the convex portion can be detected with pinpoint accuracy. This can reduce false operation furthermore. Further, it is possible to arrange that the keypad  1  covers also the other area than the character display area in order to protect the whole surface of the display area. 
         [0038]      1 : keypad,  11 : base body,  11   a : tab,  12 ,  121 ,  122  and  123 : key tops,  12   a : edge portion,  12   b : concave portion,  12   c : through hole,  12   d : marks,  12   e : character,  121   c ,  122   c  and  123   c : convex portions,  90 : tablet computer,  91 : frame part,  92 : touch panel,  92   a : screen keyboard display area,  92   b : text display area,  92   c : character display area,  100 : fingertip