Abstract:
A key switch can generate several signals is provided. The key switch includes a key top, a body, a first electronic circuit, a second electronic circuit, and a switch mechanism. Pressing the key top, the switch key generates a first signal while the first electronic circuit is closed by the switch mechanism; the switch key generates a second signal while the second electronic circuit is closed; and the switch key generates a third signal while both the first electronic circuit and the second electronic circuit is closed.

Description:
BACKGROUND 
       [0001]    1. Technical Field 
         [0002]    The present disclosure relates generally to a switch configuration for a keying operation and, more particularly, to a key-entry switch device (hereinafter referred to as key switch) preferably used for a keyboard incorporated as an input device in electronic equipment. 
         [0003]    2. Description of Related Art 
         [0004]    User input devices are used with many types of electronic devices to input data and commands. It is well known that a user may have to press more than one key of a keyboard at the same time to input a desired character or command. For example, the “1” key of the keyboard of a desktop computer can be used for both “1” and “!”. If the user presses just the one key, the default signal “1” is input. If, however, the user wants to input the “!” character, then the user should press and hold the “shift” key and then press the “1” key. 
         [0005]    The above becomes even more inconvenient when adopted by handheld or portable devices such as PDAs, where space is at a premium and it is difficult to selectively press more than one key at a time. Therefore, what is needed is a key switch that can generate several different signals. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0006]    The components of the drawings are not necessarily drawn to scale, the emphasis instead being placed upon clearly illustrating the principles of a key switch. Moreover, in the drawings, like reference numerals designate corresponding parts throughout several views. 
           [0007]      FIG. 1  is a schematic view showing a structure of a key switch in accordance with an exemplary embodiment, the key switch including a key top, a switch mechanism, a body, a first electronic circuit, and a second electronic circuit. 
           [0008]      FIG. 2  is a schematic diagram illustrating the key switch of  FIG. 1  in a first state when a second metal sheet of the switch mechanism is moved downwardly and contacts the first electronic circuit as the key top is pressed. 
           [0009]      FIG. 3  is an illustration for explaining the key switch of  FIG. 1  in a second state when a second metal sheet of the switch mechanism is moved downwardly and contacts the second electronic circuit as the key top is pressed further. 
           [0010]      FIG. 4  is an illustration for explaining the key switch of  FIG. 1  in a third state when the first metal sheet contacts the further electronic circuit and the first metal sheet contacts the first electronic circuit simultaneously. 
           [0011]      FIG. 5  is an illustration for explaining the key switch of  FIG. 1  in a fourth state when both metal sheets do not contact the electronic circuits. 
           [0012]      FIG. 6  is an illustration for explaining the key switch of  FIG. 1  in a another state when the first metal sheet contacts the bottom of the first electronic circuit while the key switch is restored to the original position. 
       
    
    
     DETAILED DESCRIPTION 
       [0013]    The embodiments of the present invention are described below in detail, with reference to the accompanying drawings. 
         [0014]      FIG. 1  is a schematic view showing a structure of a key switch in accordance with an exemplary embodiment. The key switch  1  includes at least a key top  12 , a switch mechanism  13 , a body  15 , a first electronic circuit  21 , and a second electronic circuit  22 . Each of the electronic circuits  21  and  22  has two contact sections. For example, in the embodiment as shown in  FIG. 1 , the first electronic circuit  21  has two contact sections  21   a , and the second electronic circuit  22  has two contact sections  22   a . In this embodiment the key switch can be in any one of four states. A first state when it is not being pressed, a second state where it is partially pressed, a third stated when it is pressed even further, and a fourth state when it is fully pressed. Each state can produce a unique signal according to which circuits are opened and closed at that state. In other embodiments more or less states are possible and will be evident from the explanation of the present embodiment below. 
         [0015]    The key top  12 , disposed above the switch mechanism  13 , is configured to be pressed by a user. The key top  12  can be upwardly and downwardly moved, by being pressed and through the resilient interlocking action of the switch mechanism  13  respectively. In the exemplary embodiment, the key top  12  is made of insulation material, and the key top  12  can be a dish-like component having a generally rectangular shape. 
         [0016]    The switch mechanism  13  is configured for selectively contacting the contact sections of the electronic circuits  21  and/or  22  in accordance with a vertical (upward-and-downward) movement of the key top  12 . Starting with the key top  12  as the top most portion, the switch mechanism  13  includes a first metal sheet  13   a , a first elastic element  13   b , a second metal sheet  13   c , and a second elastic element  13   d . The first metal sheet  13   a  and the second metal sheet  13   c  are connected to opposite ends of the first elastic element  13   b  respectively. The first metal sheet  13   a  is mounted under the key top  12 . One end of the second elastic element  13   d  is connected to the second metal sheet  13   c , and the other end of the second elastic element  13   d  is connected to an upper surface of the support plate  15   a . When the key top  12  is pressed, the downward movement elastically deforms the first metal sheet  13   a . The length of the first metal sheet  13   a  is longer than the distance between the two contact sections  21   a  of the first electronic circuit  21 , the second metal sheet is elastic, and the length of the second metal sheet  13   c  is longer than the distance between the two contact sections  22   a  of the second electronic circuit  22 , to ensure proper connectivity of first/second metal sheets  13   a / 13   c  with the electronic circuits  21 / 22  in use. In addition, the elasticity coefficient of the first elastic element  13   b  is greater than the elasticity coefficient of the second elastic element  13   d . Accordingly, as the key top  12  is pressed, the deformation of the second elastic element  13   d  is greater than the deformation of the first elastic element  13   b.    
         [0017]    The first electronic circuit  21  is mounted over the second electronic circuit  22 . Further, both the first electronic circuit  21  and the second circuit  22  are fixed on the body  15 . 
         [0018]    When the key top  12  is partially pressed, the first elastic element  13   b  and the second elastic element  13   d  are both deformed, accordingly, the first metal sheet  13   a  and the second metal sheet  13   c  are moved down. The second metal sheet  13   c  is moved down and contacts the contact sections  21   a , the first electronic circuit  21  is closed, and the key switch  10  generates a first signal, see  FIG. 2 . 
         [0019]    Referring to  FIG. 3 , as the key top  12  is pressed even further, the second metal sheet  13   c  is deformed and passes beyond the contact sections  21   a , to contact the contact sections  22   a , thus the second electronic circuit  22  is closed, and the key switch  10  generates a second signal. 
         [0020]    Referring to  FIG. 4 , when the key top  12  is fully pressed, the first metal sheet  13   a  contacts the contact sections  21   a , and at the same time, the second metal sheet  13   c  contacts the contact sections  22   a , that is, both the first electronic circuit  21  and the second electronic circuit  22  are closed, and the key switch  10  generates a third signal. In addition, when the second metal sheet  13   c  contacts the contact sections  22   a , the second metal sheet  13   c  is supported by the second electronic circuit  22   a , accordingly, the second elastic element  13   d  is maintained in a current deformed state and will not be deformed further. 
         [0021]    Referring to  FIGS. 1 and 5 , in this embodiment, when the contact sections  21   a  and  22   a  are not closed, namely, both the first electronic circuit  21  and the second electronic circuit  22  are not closed, no signal is generated by the key switch  10 . 
         [0022]    The upper surface of the second metal sheet  13   c  is covered with a resinous material, or other insulation. When the key top  12  is released, the first elastic element  13   b  and the second elastic element  13   d  rebound, and the key top  12  returns to the original position. During returning the key top  12  to the original position, while the second metal sheet  13   c  contacts the bottom of a pair of the first/second contact sections (see  FIG. 6 ), the key switch  10  generates no signal because of insulation of the upper surface of the second metal sheet  13   c.    
         [0023]    For the purpose of easily understanding the exemplary embodiment, an exemplary process of generating three signals, for example, three numerals (e.g., 1, 2, 3) through the key switch  10  is described as follows. As the user presses the key top  12  slightly, the switch mechanism  13  moves downwardly, when the second metal sheet  13   c  contacts the contact sections  21   a , the first electronic circuit  21  is closed, and the key switch  12  generates the first signal, e.g., numeral “1”. As the user presses the key top  12  even further, when the second metal sheet  13   c  contacts a the contact sections  22   a , the second electronic circuit  22  is closed, and the key switch  10  generates the second signal, e.g., numeral “2”. As the user presses the key top  12  further more, when the first metal sheet  13   a  contacts the contact sections  21   a  and the second metal sheet  13   c  contacts the contact sections  22   a  synchronously, both the first electronic circuit  21  and the second electronic circuit  22  are closed, and the key switch  10  generates the third signal, e.g., numeral “3”. Therefore, three numerals (1, 2, 3) can be obtained through the key switch  10 . 
         [0024]    Although the present invention has been specifically described on the basis of the exemplary embodiment thereof, the invention is not to be construed as being limited thereto. Various changes or modifications may be made to the embodiment without departing from the scope and spirit of the invention.