Abstract:
A keypad assembly for a mobile terminal includes a shielding element to prevent sound leakage from or into a sound port that is used to guide sound to a terminal microphone. A mobile terminal may include a printed circuit board (PCB) coupled to a keypad assembly and mounted within a case or housing, wherein a microphone is integral with the PCB. The shielding element is located between the microphone and the terminal case to form part of the sound port, and may be integrated with the keypad assembly.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
       [0001]    Pursuant to 35 U.S.C. § 119(a), this application claims the benefit of earlier filing date and right of priority to Korean Patent Application No. 10-2006-0112159, filed on Nov. 14, 2006, the contents of which are hereby incorporated by reference in their entirety. 
       FIELD OF THE INVENTION 
       [0002]    The present invention relates to a keypad assembly, and more particularly, to a keypad assembly capable of preventing sound from leaking from or into a sound port used for directing sound to a microphone installed in a mobile terminal. 
       DISCUSSION OF THE RELATED ART 
       [0003]    Generally, mobile terminals include mobile phones, PDAs, and the like, which are hand-held wireless communication devices capable of allowing individuals to exchange images, voice communications, and text messages, or to use a variety of services over network connections. 
         [0004]    Recently, mobile terminals include many more functions than the basic function of providing simple communication similar to telephones. Current terminals include advanced features such as a game player, a MP3 file player, a digital camera, a video on demand (VOD) player, and an electrical dictionary. 
         [0005]    Terminals have been developed into a variety of shapes including bar-type, flip-type, folder-type, and slide-type terminals. Consumers prefer smaller and lighter terminals, and the thickness of the terminals has been increasingly reduced. Very thin bar-type terminals are now sold. 
         [0006]    Referring to  FIGS. 1 and 2 , a conventional slide-type terminal comprises a main body  10  including a keypad  11  for text input, and a sliding cover  20  coupled to a front surface of the main body  10 , wherein the sliding cover  20  slides over the main body  10 . 
         [0007]    The main body  10  has a battery  13  coupled to a rear surface and a microphone opening  12  for receiving voice signals. The sliding cover  20  has a liquid crystal screen  21  for displaying an image, an speaker opening  22  for providing sound output, and function keys  23  to execute special functions. 
         [0008]    To have a conversation using the slide-type terminal, the sliding cover  20  is opened exposing the keypad  11  and the microphone opening  12 . A call is initiated by providing calling numbers using the keypad  11 , and when connected, a conversation is accomplished using the microphone opening  12  and the speaker opening  22 . 
         [0009]    In the above description, a microphone  32  is mounted on a circuit board  30  at a position below the microphone opening  12 . The microphone  32  serves to convert sound, guided into the microphone  32  through the microphone opening  12 , into electrical signals. When a gap exists between the microphone opening  12  and the microphone  32 , sound may leak from this gap. That is, a voice conversation may leak from the gap between the microphone opening  12  and the microphone  32  into the interior of the main body  10  rather than being wholly introduced into the microphone  32 . This creates the problem of attenuating the sound volume transmitted to the microphone  32 . 
         [0010]    Furthermore, sound from the speaker (not shown) may leak from a similar gap beneath the speaker opening  22  may be transmitted to the microphone  32  by passing through interior portion of the sliding cover  20  and the main body  10  thereby causing feedback to the other party. This feedback causes the other party to hear an echo of his voice transmitted by microphone  22 . 
       SUMMARY OF THE INVENTION 
       [0011]    Accordingly, the present invention is directed to a keypad assembly and a mobile terminal using the keypad assembly that substantially overcome one or more problems due to limitations and disadvantages of the related art. 
         [0012]    An object of the present invention is to provide a keypad assembly capable of preventing sound leaking into or from a sound guide. A shielding element may be integrally formed with the keypad assembly. 
         [0013]    Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention. The objectives and other advantages of the invention may be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings. 
         [0014]    In one embodiment, a keypad assembly includes a keypad having user input keys, and a sound port formed in the keypad and configured to direct sound to a microphone. The keypad assembly also includes a shielding element cooperating with the sound port and which is configured to direct sound to the microphone, wherein the shielding element is located between the keypad and the microphone. The shielding element may be located relative to a portion of a top side of the microphone and extending along at least a portion of a side or sides of the microphone. The shielding element is configured to fill at least a portion of a gap between the keypad and a printed circuit board. 
         [0015]    The shielding element may be located between the keypad and a first side of a printed circuit board (PCB) and may be configured to direct the sound to the microphone located on a second side of the PCB. 
         [0016]    The shielding element may be integrally formed with the keypad, or may be a separate member configured to be attached to the keypad. 
         [0017]    The user input keys form a two-dimensional array of keys, and the sound port may be located between adjacent keys of the input keys. 
         [0018]    In another embodiment, a mobile terminal includes a circuitry supporting substrate having circuitry for implementing functions associated with the mobile terminal, a microphone coupled to the circuit board and configured to receive sound, and a keypad assembly configured to cooperate with the circuitry supporting substrate and microphone, wherein the keypad assembly has a keypad comprising user input keys and a first sound port formed in the keypad and configured to direct sound to the microphone. The microphone may be coupled to either a top side or a lower side of the circuitry supporting substrate. 
         [0019]    The terminal may also include a second sound port formed in the circuitry supporting substrate, in which the second sound port is located to cooperate with the first sound port and is configured to direct the sound to the microphone. 
         [0020]    The keypad assembly further includes a shielding element cooperating with the first sound port and which is configured to direct the sound to the microphone, in which the shielding element is located relative to a portion of a top side of the microphone and extending along at least a portion of a side or sides of the microphone. The shielding element is located between the keypad and the microphone, and is formed to fill at least a portion of a gap between the keypad and a printed circuit board. The shielding element may be integrally formed with the keypad or may be a separate member configured to be attached to the keypad. 
         [0021]    The user input keys form a two-dimensional array of keys, and the first sound port may be located between adjacent keys of the input keys. 
         [0022]    The terminal may also include a housing for enclosing the circuitry supporting substrate, the microphone, and the keypad assembly, and a second sound port formed in the housing and configured to cooperate with the first sound port to direct the sound to the microphone. 
         [0023]    It is to be understood that both the foregoing general description and the following detailed description of the present invention are exemplary and explanatory and are intended to provide further explanation of the invention as claimed. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0024]    The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this application, illustrate embodiments of the invention and together with the description serve to explain the principle of the invention. 
           [0025]      FIG. 1  is a perspective view of a conventional mobile terminal. 
           [0026]      FIG. 2  is a plan view showing a microphone installed in the conventional mobile terminal. 
           [0027]      FIG. 3  is a sectional perspective view illustrating a shielding element of the terminal according to one embodiment of the present invention. 
           [0028]      FIG. 4  is a plan view of the mobile terminal of  FIG. 3 . 
           [0029]      FIG. 5  is a plan view illustrating a keypad assembly having a shielding element according to one embodiment of the present invention. 
           [0030]      FIG. 6  is a bottom view of the keypad assembly shown in  FIG. 5 . 
           [0031]      FIG. 7  is a plan view of a circuit board having a microphone according to another embodiment of the present invention. 
           [0032]      FIG. 8  is a plan view of a keypad having a shielding element as shown in  FIG. 7 . 
           [0033]      FIG. 9  is a partial enlarged view showing the installation of a shielding element associated with the microphone of  FIG. 8 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0034]    Reference will now be made in detail to the embodiments of the present invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts. 
         [0035]    Referring to  FIGS. 3 to 6 , a keypad assembly, according to one embodiment of the present invention, comprises a keypad  150 , at least one sound port  130  located on the keypad  150  and used to guide sound to a microphone  120 , and a shielding element  140  filling a gap between the microphone  120  and the sound port  130 . The shielding element  140  prevents sound leaking into the microphone  120  from the main body  100 . 
         [0036]    A terminal having the keypad assembly comprises a circuit board  110  having electronic components implementing the terminal functions, the microphone  120  located on the circuit board  110  to receive sound, and the keypad assembly provided on an upper portion of the circuit board  110 . 
         [0037]    Although one embodiment of the present invention will be described based on the configuration provided on a main body  100  of a slide-type terminal, it should be understood that the configuration may be provided on a sliding cover (not shown) rather than the main body  100 . The configuration described above also may be applicable to other types of terminals, including folder-type and bar-type terminals. 
         [0038]    The microphone  120  is located on the circuit board  110  and converts sound into electrical signals. The microphone may be located separately from but electrically connected to the circuit board  110 . A small-size high-performance semiconductor microphone  120  may be used. 
         [0039]    When the microphone  120  is installed on the circuit board  110 , the microphone  120  is typically attached to a lower surface of the circuit board  110 . Such an arrangement minimizes the overall thickness of the terminal. An alternative configuration, in which the microphone  120  is mounted on another position of the circuit board  110 , will be described later with respect to another embodiment. 
         [0040]    The sound port  130  is provided to guide external sound to the microphone  120 . To prevent the leakage of sound being introduced into the microphone  120 , the shielding element  140  is provided to fill the gap between the microphone  120  and the sound port  130 . 
         [0041]    The shielding element  140  seals the sound path thereby preventing sound leakage and eliminates attenuation of the sound transmission. Further, the shielding element prevents extraneous sound from entering the sound path and effectively eliminates feedback from the speaker (not shown) to the microphone  120 . 
         [0042]    The shielding element  140  has a first hole  142  for allowing the sound, introduced into the sound port  130 , to be transmitted to the microphone  120 . The first hole  142  of the shielding element  140  defines the sound path while preventing sound leakage into or from the first hole  142 . 
         [0043]    The circuit board  110  has a second hole  112  near the microphone  120 . The second hole  112  allows the sound to be transmitted through the upper and lower surfaces of the circuit board  110 . Since the microphone  120  is attached to the lower surface of the circuit board  110 , preferably, the second hole  112  is formed at a position of the circuit board  110  corresponding to the microphone  120  in order to guide sound into the microphone  120 . 
         [0044]    In this embodiment, the shielding element  140  is provided in a gap between the upper surface of the circuit board  110  and the sound port  130 , thereby preventing the sound leakage into the microphone  120 . The sound port  130  may be a perforation in the case  102  that forms the outer surface of the main body  100 . In this case, the sound port  130  is exposed to the outside similar to a conventional microphone opening, and serves to guide sound. 
         [0045]    However, according to one embodiment, the sound port  130  is preferably integrated with the keypad  150 . When the sound port  130  is integrated with the keypad  150 , a microphone opening  104  is provided in the case  102  at a position corresponding to the sound port  130 , enabling the sound port  130  to communicate with the outside. 
         [0046]    As shown in  FIGS. 5 and 6 , the keypad  150 , sound port  130 , and shielding element  140  may constitute a single keypad assembly. Specifically, the sound port  130  may be located in a lower portion of the keypad  150 . A plurality of keypad fixing holes  152  are arranged along the periphery of the keypad  150 . The keypad fixing holes  152  are engaged with protrusions (not shown) formed in the circuit board  110  or case  102 , to secure the keypad  150  at a fixed position. The position of the sound port  130  may be appropriately selected so as not to overlap with the keypad fixing holes  152 . 
         [0047]    Here, the sound port  130  can be provided at various desired positions on the keypad  150 , for example, at the middle of the lower portion or the left or right distal end of the lower portion of the keypad  150 , or the center portion of the keypad  150 . The position of the sound port  130  can be appropriately selected so as not to interfere with the key input operation of the keypad  150 . Then, positions of the shielding element  140 , microphone  120 , first hole  142 , and second hole  112  are determined to correspond to the position of the sound port  130 . 
         [0048]    The shielding element  140  may be integrally formed with the keypad  150 . Specifically, the shielding element  140  may be integrally formed at the lower surface of the keypad  150  at the same position as the sound port  130 . For example, if the keypad  150  is fabricated by insert injection molding, the shielding element  140  is also fabricated by injection molding together with the keypad  150  and thus, can be integrally formed at a position of the keypad  150 . 
         [0049]    If the shielding element  140  is integrally formed with the keypad  150 , attachment and alignment errors are eliminated thereby reducing assembly interference problems. The shielding element  140  also may be prepared as a separate member and attached to the lower surface of the keypad  150  using an adhesive or other method of fastening. 
         [0050]    Whether the shielding element  140  is integrally formed or prepared as the separate member to be attached as described above, the shielding element  140  is fixedly mounted along with the keypad  150  in the course of assembling the terminal. Therefore, by carefully inserting the keypad fixing holes  152  on the protrusions of the keypad  150  or case  102 , the sound port  130 , first hole  142 , and second hole  112  can be aligned. 
         [0051]    As described above, manufacturing and assembling the keypad  150 , sound port  130 , and shielding element  140  as a single assembly has the advantages of reducing the rate of defective products and increasing the convenience and accuracy of overall assembly. 
         [0052]    A plurality of first holes  142  may be perforated in the shielding element  140  to diversify the path of sound. Of course, it is preferable that, when the plurality of first holes  142  is provided, a plurality of second holes  112  and a plurality of sound ports  130  be provided corresponding to the number of the first holes  142 . 
         [0053]    The shielding element  140  may be made of a flexible material and when integrally formed with the keypad  150 , the shielding element  140  may be made of the same material as that of the keypad  150 . 
         [0054]    Preferably, the shielding element  140  has a thickness larger than the distance between the upper surface of the circuit board  110  and the sound port  130 . With this configuration, when the shielding element  140  is assembled together with the keypad  150 , the circuit board  110 , and the case  102 , the shielding element  140  is compressed between the circuit board  110  and the sound port  130 . Since the shielding element  140  is made of a flexible material, the shielding element  140  can come into close contact with contact surfaces of both the circuit board  110  and the sound port  130 . As a result, the leakage of sound can be more efficiently prevented. 
         [0055]    The case  102  is assembled such that the microphone opening  104  and the sound port  130  are in close contact with each other allowing sound to be guided through the microphone opening  104 , sound port  130 , first hole  142 , and the second hole  112 , and introduced into the microphone  120  without the possibility of leakage. 
         [0056]    The shape of the shielding element  140  can be changed to conform to the installation space. Although the shielding element  140  is illustrated with a rectangular cross section when viewed from a direction parallel to the keypad  150 , other polygonal or circular cross sectional shapes are also possible. 
         [0057]    Another embodiment is described with reference to  FIGS. 7 to 9 . A microphone  220  according to one embodiment is attached to the upper surface of the circuit board  210 . Although shown at the center of the circuit board  210 , the microphone  220  may be located according to design requirements. 
         [0058]    When the microphone  220  is located on the upper surface of the circuit board  210 , the shielding element  240  is configured to cover a portion of the microphone  220  extending upward from the upper surface of the circuit board  210 . 
         [0059]    Similarly, the shielding element  240  may be provided on a keypad  250 . The shielding element  240  may be in the form of a cap protruding from the upper surface of the keypad  250 , to cover the microphone  220 . 
         [0060]    The keypad  250  in this embodiment has substantially the same configuration as the previous embodiment except for the configuration of the shielding element  240 . Accordingly, other elements of the keypad  250  including, for example, keypad fixing holes  252 , are identical to those of the previous embodiment. 
         [0061]    Meanwhile, in the present embodiment, it is preferable that a sound port (not shown) be formed in a case (not shown) forming the outer appearance of the terminal body. The sound port is located above the shielding element  240  when assembled in the case. When completely assembled, the sound port is in close contact with the shielding element  240 . The shielding element  240  has a first hole  242  allowing sound to be introduced into the sound port and transmitted to the microphone  220 . 
         [0062]    In conclusion, the sound port and the first hole  242  are aligned, and sound is transmitted to the microphone  220  along the sound path defined by both the sound port and the first hole  242 . In this case, the shielding element  240  seals a gap between the sound port and the microphone  220  preventing sound leakage. The shielding element  240  has a thickness sufficient to seal the gap between the sound port and the microphone  220 . 
         [0063]    It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the inventions. Thus, it is intended that the present invention covers the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.