Abstract:
A keyboard. A membrane circuit board includes a plurality of switches. At least one keycap is disposed on the membrane circuit board and includes a plurality of activating pillars respectively corresponding to and separated from the switches. When the keycap is moved toward the membrane circuit board, one of the activating pillars compresses one of the switches, outputting a signal corresponding to the keycap.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The invention relates to keyboards, and more particularly to keyboards providing enhanced operational sensitivity. 
         [0003]    2. Description of the Related Art 
         [0004]    A conventional key structure of a remote control comprises a keycap, a conductive elastomer, a switch (such as an edge connector), and a printed circuit board. The switch is disposed on the printed circuit board. The conductive elastomer is connected to the keycap and corresponds to the switch. An operator can press the keycap, forcing the conductive elastomer connected thereto to compress the switch. The switch is thus activated and outputs a corresponding signal. 
         [0005]    Nevertheless, the conventional key structure has many drawbacks. To effectively activate the switch, the operator must press the center of the keycap. Specifically, when the operator presses corners of the keycap, the conductive elastomer often cannot compress the switch, causing ineffective operation of the key structure. Moreover, due to manufacturing considerations, the conventional key structure cannot provide waterproof and dustproof functions. Furthermore, the conductive elastomer often contains silicon oil. After long-term use, the conductive elastomer is easily broken and the silicon oil leaks from the interior thereof, causing damage to the entire key structure. Additionally, the conductive elastomer is expensive, such that the manufacturing costs of the key structure cannot be reduced. 
         [0006]    Moreover, referring to  FIG. 4 , a conventional key structure  1  comprises a circuit board  10  and a key assembly  20 . The key assembly  20  comprises multiple keys  21  and multiple protrusions  22 . Each protrusion  22  corresponds to each key  21  and is disposed thereunder. When one of the keys  21  is pressed, the protrusion  22  disposed thereunder compresses the circuit board  10 , outputting a corresponding signal. 
         [0007]    Nevertheless, as the entire key assembly  20  often comprises soft material, power or kinetic energy from pressing the key  21  is offset by deformation of the key assembly  20 . Displacement of the corresponding protrusion  22  is insufficient and thus the protrusion  22  cannot exactly compress the circuit board  10 . Accordingly, the key  21  must be pressed again to function, causing inconvenience of operation. The aforementioned problem is particularly obvious with a multiple key. 
         [0008]    Hence, there is a need for a keyboard providing soft tactile sensitivity for the operator and appropriate rigidity for efficient operation. 
       BRIEF SUMMARY OF THE INVENTION 
       [0009]    A detailed description is given in the following embodiments with reference to the accompanying drawings. 
         [0010]    An exemplary embodiment of the invention provides a keyboard comprising a membrane circuit board and at least one keycap. The membrane circuit board comprises a plurality of switches. The keycap is disposed on the membrane circuit board and comprises a plurality of activating pillars respectively corresponding to and separated from the switches. When the keycap is moved toward the membrane circuit board, the activating pillars compress the switches, outputting a signal corresponding to the keycap. 
         [0011]    The keyboard further comprises at least one resilient member disposed between the keycap and the membrane circuit board and covering the switches and activating pillars. 
         [0012]    The activating pillars are uniformly distributed over the keycap. 
         [0013]    The activating pillars are distributed over the center and corners of the keycap, respectively. 
         [0014]    The keycap comprises elastic material. 
         [0015]    Another exemplary embodiment of the invention provides a keyboard comprising a membrane circuit board, a plurality of keycaps, and a reinforcement sheet. The membrane circuit board comprises a plurality of switches. The keycaps are disposed on the membrane circuit board and comprise elastic material. Each keycap comprises an activating pillar corresponding to each switch. One of the keycaps is provided with a multiple keycap. The reinforcement sheet is disposed between the multiple keycap and the membrane circuit board. The hardness of the reinforcement sheet exceeds that of the multiple keycap. 
         [0016]    The keycap comprises rubber. 
         [0017]    The reinforcement sheet comprises stiff plastic or metal. 
         [0018]    The stiff plastic comprises PET. 
         [0019]    The reinforcement sheet comprises a hole through which the activating pillar of the multiple keycap passes. 
         [0020]    The reinforcement sheet is integrally formed with the multiple keycap by insert molding. 
         [0021]    The reinforcement sheet is attached to the multiple keycap. 
         [0022]    The multiple keycap comprises an Enter keycap, a Shift keycap, a Space keycap, or a Backspace keycap. 
     
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0023]    The invention can be more fully understood by reading the subsequent detailed description and examples with references made to the accompanying drawings, wherein: 
           [0024]      FIG. 1A  is a partial side view of a keyboard of a first embodiment of the invention; 
           [0025]      FIG. 1B  is a partial top view of the keyboard of the first embodiment of the invention; 
           [0026]      FIG. 2A  is a partial side view of a keyboard of a second embodiment of the invention; 
           [0027]      FIG. 2B  is a partial top view of the keyboard of the second embodiment of the invention; 
           [0028]      FIG. 3A  is a partial side view of a keyboard of a third embodiment of the invention; 
           [0029]      FIG. 3B  is a partial top view of the keyboard of the third embodiment of the invention; and 
           [0030]      FIG. 4  is a schematic partial cross section of a conventional key structure. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0031]    The following description is of the best-contemplated mode of carrying out the invention. This description is made for the purpose of illustrating the general principles of the invention and should not be taken in a limiting sense. The scope of the invention is best determined by reference to the appended claims. 
       First Embodiment 
       [0032]    Referring to  FIG. 1A  and  FIG. 1B , a keyboard  100  comprises a base plate  110 , a membrane circuit board  120 , a plurality of keycaps  130 , and a plurality of resilient members  140 . 
         [0033]    The membrane circuit board  120  is disposed on the base plate  110  and comprises a plurality of switches  121 . 
         [0034]    The keycaps  130  are disposed on the membrane circuit board  120 . Each keycap  130  comprises a plurality of activating pillars  131  respectively corresponding to and separated from the switches  121 . Specifically, the disposition and number of the switches  121  of the membrane circuit board  120  correspond to those of the activating pillars  131  of the keycaps  130 . Moreover, the activating pillars  131  are uniformly distributed over each keycap  130 . More specifically, as shown in  FIG. 1B , the activating pillars  131  are distributed over the center and corners of each keycap  130 , respectively. 
         [0035]    As shown in  FIG. 1A  and  FIG. 1B , each resilient member  140  is disposed between each keycap  130  and the membrane circuit board  120  and covers the activating pillars  131  of each keycap  130  and the switches  121  corresponding thereto. 
         [0036]    When a certain keycap  130  is pressed to move toward the membrane circuit board  120 , the pillars  131  compress the switches  121 , outputting a signal corresponding to the certain keycap  130 . On the other hand, after being released, the certain keycap  130  returns to an original position by resilience provided by a corresponding resilient member  140 . 
         [0037]    Accordingly, uniformly distributed over each keycap  130  (or distributed over the center and corners of each keycap  130 , respectively), the activating pillars  131  thereof can compress the switches  121  of the membrane circuit board  120  even though the center thereof is not pressed (i.e. only corners of the keycap  130  are pressed), thereby outputting a signal corresponding thereto. Ineffective operation of the keyboard  100  is thus prevented. Namely, operational sensitivity of the keyboard  100  is effectively enhanced, such that the keyboard  100  can provide convenient and rapid operation. 
         [0038]    Moreover, as each resilient member  140  covers the activating pillars  131  of each keycap  130  and the switches  121  corresponding thereto, external particles (such as, water and dusts) cannot enter a space between each keycap  130  and the membrane circuit board  120 . The keyboard  100  thus provides waterproof and dustproof functions. 
         [0039]    Furthermore, the keyboard  100  omits conductive elastomers, thus providing reduced manufacturing costs and simplified assembly. 
         [0040]    Additionally, the keyboard  100  provides extensive applicability. For example, the keyboard  100  can be applied as a remote control or a computer input device. 
       Second Embodiment 
       [0041]    Referring to  FIG. 2A  and  FIG. 2B , a keyboard  200  comprises a base plate  210 , a membrane circuit board  220 , and a key assembly  230 . 
         [0042]    The membrane circuit board  220  is disposed on the base plate  210  and comprises a plurality of switches  221 . 
         [0043]    The key assembly  230  is disposed on the membrane circuit board  220  and covers the switches  221  of the membrane circuit board  220 . Moreover, the key assembly  230  comprises a plurality of keycaps  231 . In this embodiment, the key assembly  230  comprises elastic material. Namely, the keycaps  231  comprise elastic material, such as rubber. Each keycap  231  comprises a plurality of activating pillars  231   a  respectively corresponding to and separated from the switches  221 . Specifically, the disposition and number of the switches  221  of the membrane circuit board  220  correspond to those of the activating pillars  231   a  of the keycaps  230 . Moreover, the activating pillars  231   a  are uniformly distributed over each keycap  231 . More specifically, as shown in  FIG. 2B , the activating pillars  231   a  are distributed over the center and corners of each keycap  231 , respectively. 
         [0044]    When a certain keycap  231  is pressed to move toward the membrane circuit board  220 , the pillars  231   a  compress the switches  221 , outputting a signal corresponding to the certain keycap  231 . On the other hand, after being released, the certain keycap  231  returns to an original status by resilience itself. 
         [0045]    Accordingly, uniformly distributed over each keycap  231  (or distributed over the center and corners of each keycap  231 , respectively), the activating pillars  231   a  thereof can compress the switches  221  of the membrane circuit board  220  even though the center thereof is not pressed (i.e. only corners of the keycap  231  are pressed), thereby outputting a signal corresponding thereto. Ineffective operation of the keyboard  200  is thus prevented. Namely, operational sensitivity of the keyboard  200  is effectively enhanced, such that the keyboard  200  can provide convenient and rapid operation. 
         [0046]    Moreover, as the key assembly  230  covers the switches  221  of the membrane circuit board  220 , external particles (such as, water and dusts) cannot enter a space between the keycaps  231  and the membrane circuit board  220 . The keyboard  200  thus provides waterproof and dustproof functions. 
         [0047]    Similarly, the keyboard  200  omits conductive elastomers, thus providing reduced manufacturing costs and simplified assembly. 
         [0048]    Similarly, the keyboard  200  provides extensive applicability. For example, the keyboard  200  can be applied as a remote control or a computer input device. 
       Third Embodiment 
       [0049]    Referring to  FIG. 3A  and  FIG. 3B , a keyboard  200 ′ comprises a base plate  210 , a membrane circuit board  220 , a plurality of keycaps  231 , a plurality of keycaps  232 , and a plurality of reinforcement sheets  240  ( FIG. 3A  and  FIG. 3B  show only a keycap  232  and a reinforcement sheet  240  for simplicity of description). 
         [0050]    The membrane circuit board  220  is disposed on the base plate  210  and comprises a plurality of switches  221 . 
         [0051]    The keycaps  231  and  232  are disposed on the membrane circuit board  220  and comprise elastic material, such as rubber. In this embodiment, the keycaps  231  are common keycaps and the keycaps  232  are multiple keycaps, such as an Enter keycap, a Shift keycap, a Space keycap, and a Backspace keycap. Namely, the size of each keycap  232  exceeds that of each keycap  231 . Moreover, each keycap  231  comprises multiple activating pillars  231   a  and each keycap  232  comprises multiple activating pillars  232   a . The position and number of the switches  221  of the membrane circuit board  220  correspond to those of the activating pillars  231   a  and activating pillars  232   a . Namely, each activating pillar  231   a  or each activating pillar  232   a  corresponds to and is separated from each switch  221 . 
         [0052]    Each reinforcement sheet  240  is disposed between each keycap  232  (multiple keycap) and the membrane circuit board  220  and comprises a plurality of holes  241  (as shown in  FIG. 3A ) through which the activating pillars  232   a  of each keycap  232  (multiple keycap) respectively pass. Specifically, the hardness of the reinforcement sheets  240  exceeds that of the keycaps  232  (multiple keycaps). For example, the reinforcement sheets  240  may comprise stiff plastic (such as PET) or metal, such that the hardness of the reinforcement sheets  240  exceeds that of the keycaps  232  (multiple keycaps) comprising rubber. Moreover, each reinforcement sheet  240  may be attached to each keycap  232  (multiple keycap) or integrally formed with each keycap  232  (multiple keycap) by insert molding. 
         [0053]    When the keycap  232  (multiple keycap) is pressed, the keycap  232  (multiple keycap) and reinforcement sheet  240  move toward the membrane circuit board  220 . The activating pillars  232   a  of the keycap  232  (multiple keycap) compress the switches  221  of the membrane circuit board  220 , outputting a signal corresponding to the keycap  232  (multiple keycap). 
         [0054]    Accordingly, as the rubber keycap  232  (multiple keycap) combined with the reinforcement sheet  240  provides enhanced rigidity, hard and soft tactile sensitivity can be obtained when an operator presses the keycap  232  (multiple keycap). Moreover, as the rubber keycap  232  (multiple keycap) combined with the reinforcement sheet  240  provides enhanced rigidity, the switches  221  of the membrane circuit board  220  can be exactly compressed when the keycap  232  (multiple keycap) is pressed, reducing inconvenience of operation. Additionally, as the reinforcement sheet  240  is disposed between the keycap  232  (multiple keycap) and the membrane circuit board  220 , aesthetical appearance of the keyboard  200 ′ is not adversely affected. 
         [0055]    While the invention has been described by way of example and in terms of preferred embodiment, it is to be understood that the invention is not limited thereto. To the contrary, it is intended to cover various modifications and similar arrangements (as would be apparent to those skilled in the art). Therefore, the scope of the appended claims should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements.