Patent Publication Number: US-9852854-B1

Title: Slim-type keyboard

Description:
FIELD OF THE INVENTION 
     The present invention relates to a slim-type keyboard, and more particularly to a slim-type keyboard with cantilever strips. 
     BACKGROUND OF THE INVENTION 
     As known, keyboards are indispensable input devices for people in the modern societies. Generally, plural keys are installed on a top surface of the keyboard. Via the keyboard, the user can press one or more keys to input a command. However, the key of the conventional keyboard has to be provided with a scissors-type connecting element. Since the scissors-type connecting element occupies a lot of space, the thickness of the conventional keyboard is larger. For solving this drawback, a slim-type keyboard is introduced into the market. The slim-type keyboard is equipped with a cantilever structure in replace of the scissors-type connecting element. Generally, the cantilever structure comprises a connection end and a suspension end. The cantilever structure is disposed under the corresponding key to support the key. That is, the bottom surface of each key is contacted with the connection end and the suspension end. 
     However, the use of the cantilever structure as the support structure of the key still has some drawbacks. For example, when the key is pressed by the user&#39;s finger, the connection end and the suspension end are correspondingly moved downwardly. The traveling distance (i.e., the downwardly movable distance) of the suspension end is certainly larger than the traveling distance of the connection end. Consequently, while a single key is pressed down, the key region near the suspension end and the key region of the connection end provide different tactile feels to the user. Under this circumstance, the user feels the discomfort of operating the keyboard. 
     Moreover, there is a vacant region between every two adjacent keys of the conventional keyboard. The foreign matters such as dust particles or water drops readily fall down to a circuit board of the keyboard through the vacant region. The dust particles or water drops may result in a poor contact problem of the circuit board or cause damage of the circuit board. Therefore, the conventional keyboard needs to be further improved. 
     SUMMARY OF THE INVENTION 
     The present invention provides a slim-type keyboard with specially-designed cantilever strips. The cantilever strip comprises a U-shaped groove. When different regions of the cantilever strip are pressed, the tactile feel is identical. 
     In accordance with an aspect of the present invention, there is provided a slim-type keyboard. The slim-type keyboard includes a first flexible layer, a pressed frame and a circuit board. The first flexible layer includes plural pressed regions. The pressed frame is disposed under the first flexible layer. The pressed frame includes plural hollow regions and plural cantilever strips. The plural cantilever strips are defined by the plural hollow regions. Each of the plural cantilever strips includes a U-shaped groove, a connection end and a suspension end. The U-shaped groove opens to the suspension end. The plural cantilever strips are covered by the first flexible layer. The pressed regions are disposed over and aligned with the corresponding cantilever strips. When one of the plural pressed regions is pressed, the corresponding cantilever strip is pushed downwardly. The circuit board assembly includes a circuit board and plural dome switches. The plural dome switches are disposed on the circuit board. The plural cantilever strips are disposed over and aligned with the corresponding dome switches. When one of the plural cantilever strips is pushed downwardly, the corresponding dome switch is triggered. 
     In an embodiment, the first flexible layer is a one-piece structure, and the first flexible layer is made of a plastic material, a leather material or a fabric material. 
     In an embodiment, the plural pressed regions are protruded upwardly from a top surface of the first flexible layer, and a symbol or a character is printed on the corresponding pressed region. Alternatively, the plural pressed regions are formed on a top surface of the first flexible layer, and a symbol or a character is printed on the corresponding pressed region. 
     In an embodiment, the slim-type keyboard further includes a second flexible layer, and the second flexible layer is disposed under the circuit board assembly. A peripheral region of the first flexible layer and a peripheral region of the second flexible layer are attached on each other. An accommodation space is defined by the first flexible layer and the second flexible layer collaboratively. The pressed frame and the circuit board assembly are accommodated within the accommodation space. 
     In an embodiment, the circuit board assembly further includes a supporting plate, and the supporting plate is arranged between the circuit board and the second flexible layer. The supporting plate is a glass-reinforced epoxy laminate substrate (FR-4), a plastic substrate or a metal substrate, and the circuit board is a membrane circuit board. 
     In an embodiment, the circuit board includes a first slot, and the supporting plate includes a second slot. After the connection end of the cantilever strip is penetrated downwardly through the first slot and the second slot, the connection end is bent to form the bent structure. The bent structure has a top surface and a bottom surface. The top surface of the bent structure is contacted with the supporting plate. The bottom surface of the bent structure is contacted with the second flexible layer. 
     In an embodiment, the second flexible layer comprises a concave structure, and the bent structure is accommodated within the concave structure of the second flexible layer. 
     In an embodiment, the domes switches are metal dome switches or rubber dome switches. 
     In an embodiment, the slim-type keyboard fourth includes a first adhesive, and the first adhesive is arranged between the first flexible layer and the pressed frame. The first flexible layer and the pressed frame are combined together through the first adhesive. 
     In an embodiment, the slim-type keyboard fourth includes a second adhesive, and the second adhesive is arranged between the circuit board assembly and the second flexible layer. The circuit board assembly and the second flexible layer are combined together through the second adhesive. 
     In an embodiment, the circuit board is used as a supporting plate, and the supporting plate is a glass-reinforced epoxy laminate substrate (FR-4). The plural dome switches are disposed on the supporting plate. 
     The above objects and advantages of the present invention will become more readily apparent to those ordinarily skilled in the art after reviewing the following detailed description and accompanying drawings, in which: 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic perspective view illustrating the appearance of a slim-type keyboard according to an embodiment of the present invention; 
         FIG. 2  is a schematic exploded view illustrating a portion of the slim-type keyboard according to a first embodiment of the present invention; 
         FIG. 3  is a schematic top view illustrating the pressed frame of the slim-type keyboard according to the first embodiment of the present invention; 
         FIG. 4  is a cross-sectional view illustrating a portion of the slim-type keyboard according to the first embodiment of the present invention; 
         FIG. 5  is a schematic exploded view illustrating a portion of the slim-type keyboard according to a second embodiment of the present invention; and 
         FIG. 6  is a schematic exploded view illustrating a portion of the slim-type keyboard according to a third embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       FIG. 1  is a schematic perspective view illustrating the appearance of a slim-type keyboard according to an embodiment of the present invention. As shown in  FIG. 1 , the slim-type keyboard  1  of the present invention has no scissors-type connecting element. Consequently, the thickness of the keyboard of the present invention is reduced when compared with the conventional keyboard. The slim-type keyboard  1  comprises a first flexible layer  11  to be pressed by a user. The first flexible layer  11  comprises plural pressed regions  110 . A symbol or a character is printed on each pressed region  110 . Consequently, the pressed region  110  can be recognized by the user. When the pressed region  110  is pressed by the user, a corresponding command is generated. In an embodiment, the pressed region  110  is protruded upwardly from a top surface  11   a  of the first flexible layer  11 . Alternatively, in another embodiment, the pressed region  110  is formed on the top surface  11   a  of the first flexible layer  11  and at the same level as the top surface  11   a  of the first flexible layer  11 . 
       FIG. 2  is a schematic exploded view illustrating a portion of the slim-type keyboard according to a first embodiment of the present invention.  FIG. 3  is a schematic top view illustrating the pressed frame of the slim-type keyboard according to the first embodiment of the present invention. For succinctness, only nine pressed regions  110  of the slim-type keyboard  1  are shown in  FIGS. 2 and 3 . Please refer to  FIGS. 2 and 3 . The slim-type keyboard  1  comprises the first flexible layer  11 , a pressed frame  12 , a circuit board assembly  13  and a second flexible layer  14 . For assembling the slim-type keyboard  1 , the peripheral region of the first flexible layer  11  and the peripheral region of the second flexible layer  14  are attached on each other. Consequently, an accommodation space is defined by the first flexible layer  11  and the second flexible layer  14  collaboratively. The pressed frame  12  and the circuit board assembly  13  are accommodated within the accommodation space. That is, the components of the slim-type keyboard  1  from top to bottom include the first flexible layer  11 , the pressed frame  12 , the circuit board assembly  13  and the second flexible layer  14  sequentially. 
     Preferably but not exclusively, the bottommost layer of the slim-type keyboard  1  is the second flexible layer  14 . Optionally, the second flexible layer  14  is omitted. Under this circumstance, the circuit board assembly  13  is the bottommost layer of the slim-type keyboard  1 . Alternatively, the second flexible layer  14  is replaced by a rigid layer. 
     Please refer to  FIG. 3  again. The pressed frame  12  comprises a frame body  122 , plural cantilever strips  121  and plural hollow regions  120 . The contours of the cantilever strips  121  are defined by the hollow regions  120 . That is, a connection end  121   a  and a suspension end  121   b  of the cantilever strip  121  are defined by the hollow region  120 . The connection end  121   a  of the cantilever strip  121  is connected with the frame body  122 . The suspension end  121   b  of the cantilever strip  121  is a free end. Since the cantilever strips  121  of the slim-type keyboard  1  are elastically restorable, the cantilever strips  121  can replace the scissors-type connecting element of the conventional keyboard. 
     In this embodiment, the cantilever strip  121  further comprises a U-shaped groove  121   c . The U-shaped groove  121   c  is formed in an inner portion of the cantilever strip  121 . A bottom side of the U-shaped groove  121   c  is located near the connection end  121   a  of the cantilever strip  121 . The two lateral sides of the U-shaped groove  121   c  are extended along the two lateral sides of the suspension end  121   b  of the cantilever strip  121 . Consequently, the U-shaped groove  121   c  opens to the suspension end  121   b  of the cantilever strip  121 . Since the connection end  121   a  of the cantilever strip  121  is perforated by the bottom side and the two lateral sides of the U-shaped groove  121   c , an inner suspension part  123  is defined. The traveling distance of the inner suspension part  123  and the traveling distance of the suspension end  121   b  are substantially equal. Consequently, when the pressed position A near the connection end  121   a  or the pressed position B near the suspension end  121   b  is pressed by the user&#39;s finger, the tactile feel of pressing the pressed position A and the tactile feel of pressing the pressed position B are substantially identical and not distinguished. 
     Please refer to  FIGS. 2 and 3  again. The plural cantilever strips  121  are covered by the single first flexible layer  11 . Moreover, the pressed regions  110  of the first flexible layer  11  are disposed over and aligned with the plural cantilever strips  121 , respectively. Consequently, when one of the pressed regions  110  of the first flexible layer  11  is pressed, the corresponding cantilever strip  121  is pushed downwardly. In an embodiment, the first flexible layer  11  and the pressed frame  12  are combined together through a first adhesive  15 . 
       FIG. 4  is a cross-sectional view illustrating a portion of the slim-type keyboard according to the first embodiment of the present invention. Please refer to  FIGS. 2, 3 and 4 . The circuit board assembly  13  is disposed under the pressed frame  12 . The circuit board assembly  13  comprises plural dome switches  131 , a circuit board  132  and a supporting plate  133 . The domes switches  131  are metal dome switches or rubber dome switches. The domes switches  131  are disposed on the circuit board  132 . The plural cantilever strips  121  are disposed over and aligned with the plural dome switches  131 , respectively. When one of the cantilever strips  121  is pushed downwardly, the corresponding dome switch  131  is triggered. Preferably, each cantilever strip  121  has a contacting part  121   d . The contacting part  121   d  is protruded downwardly from the cantilever strip  121  and toward the circuit board assembly  13 . Consequently, the dome switch  131  can be pushed more precisely and effectively. That is, while the pressed region  110  of the first flexible layer  11  is pressed by the user, the corresponding cantilever strip  121  of the pressed frame  12  is pushed downwardly to trigger the corresponding dome switch  131  of the circuit board assembly  13 . 
     Preferably, the first flexible layer  11  is a one-piece structure, and the first flexible layer  11  is made of a plastic material, a leather material or a fabric material. As mentioned above, the first flexible layer  11  is a one-piece structure, and the top side of the pressed frame is covered by the first flexible layer  11 . Consequently, when the slim-type keyboard  1  is used, the foreign dust particles or water drops will not drop down to the circuit board  132 . In other words, the slim-type keyboard  1  has the waterproof and dust-proof benefits. 
     Moreover, the second flexible layer  14  is disposed under the circuit board assembly  13  for supporting the circuit board assembly  13 . The supporting plate  133  is arranged between the circuit board  132  and the second flexible layer  14 . The supporting plate  133  is used for supporting the circuit board  132 . Consequently, the overall structure of the slim-type keyboard  1  becomes stronger and denser. Moreover, the circuit board assembly  13  and the second flexible layer  14  are combined together through a second adhesive  16 . In an embodiment, the supporting plate  133  is a glass-reinforced epoxy laminate substrate (FR-4), a plastic substrate or a metal substrate, and the circuit board  132  is a membrane circuit board. 
       FIG. 5  is a schematic exploded view illustrating a portion of the slim-type keyboard according to a second embodiment of the present invention. Like the first embodiment, the slim-type keyboard  2  of this embodiment comprises a first flexible layer  21 , a pressed frame  22 , a circuit board assembly  23  and a second flexible layer  24 . The structures and functions of the first flexible layer  21 , the pressed frame  22 , the circuit board assembly  23  and the second flexible layer  24  are similar to the corresponding components of the first embodiment, and are not redundantly described herein. In comparison with the first embodiment, the slim-type keyboard  2  of this embodiment further comprises a raised frame  25 . The raised frame  25  is arranged between the pressed frame  22  and the circuit board assembly  23 . Due to the raised frame  25 , the pressed frame  22  and the circuit board assembly  23  are separated from each other by a predetermined distance. Consequently, when the key is pressed, the cantilever strip  221  of the pressed frame  22  has a sufficient traveling distance. 
       FIG. 6  is a schematic exploded view illustrating a portion of the slim-type keyboard according to a third embodiment of the present invention. For succinctness, only one pressed structure of the slim-type keyboard is shown. Like the first embodiment, the slim-type keyboard  3  of this embodiment comprises a first flexible layer  31 , a pressed frame  32 , a circuit board assembly  33  and a second flexible layer  34 . The pressed frame  32  comprises plural cantilever strips  321 . For succinctness, only one cantilever strip  321  is shown in  FIG. 6 . The circuit board assembly  33  comprises a circuit board  332  and a supporting plate  333 . In comparison with the first embodiment, the circuit board  332  of this embodiment further comprises a first slot  332   a  and the supporting plate  333  further comprises a second slot  333   a . Moreover, the cantilever strip  321  comprises a bent structure  3210 . Preferably, after a connection end  321   a  of the cantilever strip  321  is penetrated downwardly through the first slot  332   a  and the second slot  333   a , the connection end  321   a  is bent to form the bent structure  3210 . The bent structure  3210  has a top surface and a bottom surface. The top surface of the bent structure  3210  is contacted with the supporting plate  333 . The bottom surface of the bent structure  3210  is contacted with the second flexible layer  34 . The second flexible layer  34  comprises a concave structure  340 . The bent structure  3210  is accommodated within the concave structure  340 . Due to this design, the pressed frame  32  is combined with the circuit board assembly  33 . Like the above two embodiments, the pressed frame  32  is attached on the first flexible layer  31  through a first adhesive  35 , and the circuit board assembly  33  is attached on the second flexible layer  34  through a second adhesive  36 . Consequently, the slim-type keyboard  3  is assembled. 
     In the above three embodiments, the circuit board assembly  13 ,  23  or  33  comprises a circuit board (e.g., a membrane circuit board) and a supporting plate. In some embodiments, the supporting plate is not essential and is possibly omitted. Preferably, the circuit board has enhanced structural strength, and thus the circuit board has the function of the supporting plate. Under this circumstance, the circuit board is a glass-reinforced epoxy laminate substrate (FR-4) in replace of the membrane circuit board. 
     From the above descriptions, the slim-type keyboard of the present invention has specially-designed cantilever strips. When the cantilever strip is pressed by the user, the tactile feel of pressing the region near the connection end and the tactile feel of pressing the position near the suspension end are substantially identical. Moreover, the first flexible layer is a one-piece structure, and the top side of the pressed frame is covered by the first flexible layer. Consequently, the foreign dust particles or water drops will not drop down to the circuit board. Consequently, the slim-type keyboard has the waterproof and dust-proof benefits. 
     While the invention has been described in terms of what is presently considered to be the most practical and preferred embodiments, it is to be understood that the invention needs not be limited to the disclosed embodiments. On the contrary, it is intended to cover various modifications and similar arrangements included within the spirit and scope of the appended claims which are to be accorded with the broadest interpretation so as to encompass all modifications and similar structures.