Patent Publication Number: US-8110763-B2

Title: Key assembly and portable electronic device using the same

Description:
This application is related to co-pending U.S. Patent Applications (Publication No. US2010/0128460, US2010/0127899, US2010/0134965), entitled “KEY ASSEMBLY AND PORTABLE ELECTRONIC DEVICE USING THE SAME”, by Mu-Wen Yang et al. Such applications have the same assignee and inventorship as the present application and have been concurrently filed herewith. The above-identified applications are incorporated herein by reference. 
     BACKGROUND 
     1. Technical Field 
     The exemplary disclosure generally relates to key assemblies, and particularly to key assemblies used in portable electronic devices. 
     2. Description of Related Art 
     With the development of smaller and lighter electronic devices for portable use, key assemblies become more compact with individual keys more tightly spaced. Unfortunately, users of these portable electronics sometimes experience difficulty in activating keys that are close together; multiple and/or erroneous keys may be activated at the same time. This drawback exists not only in cellular telephones, but other portable electronic devices with key assemblies. 
     Therefore, there is room for improvement within the art. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Many aspects of the exemplary embodiments can be better understood with references to the following drawings. The components in the drawings are not necessarily drawn to scale, the emphasis instead being placed upon clearly illustrating the principles of the exemplary key assembly and portable electronic device using key assembly. Moreover, in the drawings like reference numerals designate corresponding parts throughout the several views. Wherever possible, the same reference numbers are used throughout the drawings to refer to the same or like elements of an exemplary embodiment. 
         FIG. 1  is an exploded view of one exemplary embodiment of a key assembly used in a portable electronic device, the portable electronic device including the key assembly, a housing, and a circuit board. 
         FIG. 2  is similar to  FIG. 1 , but showing the portable electronic device in another aspect. 
         FIG. 3  is an assembled, isometric view of the portable electronic device shown in  FIG. 1 . 
         FIG. 4  is a perspective view of the portable electronic device shown in  FIG. 3 . 
         FIG. 5  is a cross-sectional view of the portable electronic device shown in  FIG. 3 . 
         FIG. 6  is similar to  FIG. 4 , but one key being in pressed state. 
         FIG. 7  is a cross-sectional view of the portable electronic device shown in  FIG. 6 . 
     
    
    
     DETAILED DESCRIPTION 
     Referring to  FIGS. 1 and 2 , an exemplary embodiment of a key assembly  10  can be used on a portable electronic device  100 , such as a cellular phone or any electronic device where a key is desirable. The portable electronic device  100  includes a key assembly  10  and a circuit board  20 . The circuit board  20  has a first switch  22  and a second switch  24  spaced from the first switch  22 . The key assembly  10  is configured to press the first switch  22  and the second switch  24 , to control the circuit board  20 . 
     The key assembly  10  includes a key body  12 , two elastic elements  14  and a base plate  16 . The key body  12  and the elastic elements  14  are both mounted to the base plate  16 . The base plate  16  may be a portion of the housing of the portable electronic device  100  or may be a separate element mounted to the housing of the portable electronic device  100 . In this exemplary embodiment, the base plate  16  is a portion of the housing of the portable electronic device  100 . 
     The key body  12  includes an operating surface  1221  facing the outside of the portable electronic device, a contacting surface  1222  opposite to the operating surface  1221 , a first side surface  1223 , a second side surface  1224  opposite to the first side surface  1223 , a first end  1225  and a second end  1226  opposite to the first end  1225 . The operating surface  1221  has a trough  1227  transversely defined near a center thereof, thus the key body  12  is divided into a first key section  124  located one end of the trough  1227  and a second key section  126  located another end of the trough  1227 . The first key section  124  corresponds to the first switch  22 , the second key section  126  corresponds to the second switch  24 . The key body  12  further has two guiding blocks  1228  protruding from the first side surface  1223  and the second side surface  1224 , respectively. The guiding blocks  1228  are coaxial and are slidably assembled to the base plate  16 . 
     The operating surface  1221  has indicia  1229  respectively defined in the first key section  124  and the second key section  126 , to indicate the function of the first key section  124  and the second key section  126 . The indicia  1229  of the first key section  124  may be a “−”, to indicate the function of the second key section  126  is decreasing volume. The indicia  1229  of the second key section  126  may be a “+”, to indicate the function of the first key section  124  is increasing volume. 
     The key body  12  has a first arcuate contacting portion  1242  protruding from the contacting surface  1222  at the first key section  124 . The first contacting portion  1242  corresponds to and is configured to trigger the first switch  22 . The key body  12  has a second arcuate contacting portion  1262  protruding from the contacting surface  1222  at the second key section  126 . The second contacting portion  1262  corresponds to and is configured to trigger the second switch  24 . The first contacting portion  1242  and the second contacting portion  1262  may be constructed from an injection-molded thermoplastic elastomer and configured to produce a point contact sensation in a user&#39;s fingertip to provide tactile feedback when a user presses the key body  12 . 
     The key body  12  has a first securing section  1230  and a second securing section  1231  protruding outwardly from the first end  1225  thereof. The first securing section  1230  is spaced from and parallel to the second securing section  1231 , so a first securing space  1232  is formed between the first securing section  1230  and the second securing section  1231 . The key body  12  has a third securing section  1233  and a fourth securing section  1234  protruding outwardly from the first end  1225  thereof. The third securing section  1233  is spaced from and parallel to the fourth securing section  1234 , thus a second securing space  1235  is formed between the third securing section  1233  and the fourth securing section  1234 . In this exemplary embodiment, the first securing section  1230  and the third securing section  1233  are made of flexible material (e.g., thermoplastic elastomer), to facilitate assembling the key body  12  to the base plate  16 . The rationale of assembling the key body  12  to the base plate  16  will describe hereinafter. 
     Each elastic element  14  is an elastic plate including a U-shaped securing portion  142 , two compressing portions  144  and two rectangular resisting portions  146 . The compressing portions  144  respectively protrude from two opposite ends of the securing portion  142 . The distance between the compressing portions  144  gradually increases from the end near the securing portion  142  to the distal ends thereof. The resisting portions  146  oppositely protrude from a distal end of each compressing portion  144 . 
     The base plate  16  includes a peripheral wall  162  and a bottom wall  164  substantially perpendicularly connected to the peripheral wall  162 . The peripheral wall  162  has a hole  1621  defined therein corresponding to the key body  12 . The hole  1621  is sized and configured to engage with the key body  12 . The peripheral wall  162  has a first inner wall  1622 , a second inner wall  1623  opposite to the first inner wall  1622 , a third inner wall  1624  and a fourth inner wall  1625 , all of which are defined in the hole  1621 . The first inner wall  1622  is level with the bottom wall  164  and the second inner wall  1623  is parallel to the bottom wall  164 . The third inner wall  1624  and the fourth inner wall  1625  respectively connect the first inner wall  1622  with second inner wall  1623 . 
     The peripheral wall  162  further has two guiding grooves  1626  defined in the first inner wall  1622  and the second inner wall  1623 , respectively. The guiding grooves  1626  correspond to and are configured to accommodate the guiding blocks  1228  therein. The peripheral wall  162  has two securing grooves  1627  respectively defined in the third inner wall  1624  and the second inner wall  1623 , and the securing grooves  1627  is defined through an inner surface of the peripheral wall  162 . The securing grooves  1627  are configured to accommodate the securing portions  142  of the elastic elements  14 . Additionally, the peripheral wall  162  has a first receiving groove  1628  defined in the third inner wall  1624  and a second receiving groove  1629  defined in the fourth inner wall  1625 . The first receiving groove  1628  and the second receiving groove  1629  are both defined through an outer surface of the peripheral wall  162 . The first receiving groove  1628  is larger than and configured for accommodating the second securing section  1231 , so the second securing section  1231  can slide in the first receiving groove  1628 . The second receiving groove  1629  is larger than and configured for accommodating the fourth securing section  1234 , so the fourth securing section  1234  can slide in the second receiving groove  1629 . 
     Referring to  FIGS. 3 and 5 , to assemble the portable electronic device  100 , firstly, the securing portions  142  of the elastic elements  14  are latched in the securing grooves  1627  of the peripheral wall  162 , so the elastic elements  14  are latched to the base plate  16 . Secondly, the first securing section  1230  and the third securing section  1233  are bent to pass through the hole  1621 . Thirdly, the guiding blocks  1228  of the key body  12  are accommodated in the guiding grooves  1626  of the base plate  16 . At this time, the first securing section  1230  and the third securing section  1233  entirely enter into the base plate  16  and restore to their original state, the first securing space  1232  and the second securing space  1235  respectively accommodate one elastic element therein, the second securing section  1231  is accommodated in the first receiving groove  1628 , the fourth securing section  1234  is accommodated in the second receiving groove  1629 . Moreover, the compressing portions  144  of the elastic element are compressed to resist first end  1225  and the second end  1226 , respectively. Thus, the key body  12  is securely mounted to the base plate  16 . 
     After that, the circuit board  20  is mounted to the bottom wall  164 . At this stage, the first switch  22  is resisted against the area of the first contacting portion  1242  adjacent to the contacting surface  1222 . In other words, the first switch  22  is resisted against the first contacting portion  1242  but not against the high-point of the first contacting portion  1242 . The second switch  24  is resisted against the area of the second contacting portion  1262  adjacent to the contacting surface  1222 . In other words, the second switch  24  is resisted against the second contacting portion  1262  but not against the high-point of the second contacting portion  1262 . 
     Referring further to  FIGS. 6 and 7 , the function first key section  124  is described herein, but can also apply to the second key section  126 . Firstly, the first key section  124  is pushed in the direction of the arrow shown in  FIG. 4 , so the key body  12  is slid in the hole  1621  in the direction of the arrow shown in  FIG. 4 . At this time, the guiding blocks  1228  slide in the guiding grooves  1626 , the first end  1225  of key body  12  compress the compressing portion  144  in the first securing space  1232  to accumulate elastic force, thus the key body  12  can rebound when released. The first switch  22  moves toward to the high-point of the first contacting portion  1242 , i.e., the first contacting portion  1242  presses and triggers the first switch  22  in the direction of arrow shown in  FIG. 6 . Simultaneously, the second key section  126  moves in the direction of arrow shown in  FIG. 4 , i.e., the second switch  24  moves away from the high-point of the second contacting portion  1262 , to prevent from triggering the second switch  24 . Thus, a user&#39;s fingertip touches only one key section at a time, thus removing the possibility of hitting two keys simultaneously. 
     It is to be understood, however, that even though numerous characteristics and advantages of the exemplary disclosure have been set forth in the foregoing description, together with details of the structure and function of the disclosure, the disclosure is illustrative only, and changes may be made in detail, especially in matters of shape, size, and arrangement of parts within the principles of the disclosure to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.