Abstract:
An electronic device ( 100 ) has a multi-state antenna ground structure ( 428, 500 ) integrated into the device housing. Configuration of the electronic device ( 100 ) for use in one of at least two operable configurations automatically causes a switching of the ground structure to improve antenna efficiency. Metal plates ( 416, 424 ) are secured within movable portions ( 104, 114 ) of the device housing such that in a first configuration the metal plates are in close proximity and act as a low impedance path for switching the ground structure to a first state. In a second configuration of the electronic device ( 100 ) the plates are separated an act as a high impedance path for switching the ground structure to a second state.

Description:
TECHNICAL FIELD  
         [0001]    This patent relates generally to wireless communication devices and more particularly to an electronic device having a multi-state antenna ground structure.  
         BACKGROUND  
         [0002]    Electronics devices such as cellular telephones, pagers, portable email and Internet appliances, personal digital assistants (PDAs), and the like are becoming smaller and multifunctional. For example, a cellular telephone may incorporate an electronic organizer, or a personal digital assistant may include an integrated camera and provide wireless email, Internet access, or even cellular telephone functionality.  
           [0003]    To facilitate the multifunctional aspects of these devices, designers have adopted numerous different form factors. For example, the cellular telephone body may open clamshell-style to reveal an enlarged keypad and screen to facilitate use of the device as an electronic organizer. Alternatively, the cellular telephone may include an enlarged screen that may be rotated outwardly from the body of the telephone to facility viewing of Internet content.  
           [0004]    Antennas for wireless electronic devices have traditionally been designed to extend outwardly from a portion of the device housing. Antennas have also been constructed internal of the device housing and integral with portions of the device housing. When integrated into a movable portion of the device housing, it is necessary to ensure the antenna will operate well in each of the disparate operating positions of the device. A difficulty in the antenna design arises when the device is operated in a configuration for which the antenna has not been tuned. This is because the impedance matching of the antenna is highly dependent upon the position of the antenna relative to the user and other electronics contained within the electronic device. If the antenna is not tuned to operate in that position, it may perform poorly. Thus, there is a need for an antenna that functions efficiently in an electronic device having numerous disparate operating positions.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0005]    The present patent is illustrated by way of examples and not limitations in the accompanying figures, in which like references indicate similar elements.  
         [0006]    [0006]FIG. 1 is a front perspective view of an electronic device incorporating a multi-state ground structure in a first operating configuration.  
         [0007]    [0007]FIG. 2 is a rear perspective view of the electronic device illustrated in FIG. 1.  
         [0008]    [0008]FIG. 3 is a front perspective view of the electronic device illustrated in FIG. 1 in a second operating configuration.  
         [0009]    [0009]FIG. 4 is a schematic representation of the electronic device illustrated in FIG. 1 in the second configuration.  
         [0010]    [0010]FIG. 5 is a circuit diagram of a multi-state ground structure for an electronic device. 
     
    
     DETAILED DESCRIPTION  
       [0011]    An electronic device, such as a cellular telephone, a pager, a wireless email/Internet appliance, and the like employs a switchable antenna ground structure that switches responsive to an operating mode of the electronic device. The antenna ground structure may switch from a first ground structure state to a second ground structure state, automatically upon reconfiguration of the device from a first operable configuration to a second operable configuration.  
         [0012]    Although the following text sets forth a detailed description of numerous different embodiments of the invention, it should be understood that the legal scope of the invention is defined by the words of the claims set forth at the end of this patent. The detailed description is to be construed as exemplary only and does not describe every possible embodiment of the invention because describing every possible embodiment would be impractical, if not impossible. Numerous alternative embodiments could be implemented, using either current technology or technology developed after the filing date of this patent, which would still fall within the scope of the claims defining the invention.  
         [0013]    It should also be understood that, unless a term is expressly defined in this patent using the sentence “As used herein, the term ‘______’ is hereby defined to mean . . . ” or a similar sentence, there is no intent to limit the meaning of that term, either expressly or by implication, beyond its plain or ordinary meaning, and such term should not be interpreted to be limited in scope based on any statement made in any section of this patent (other than the language of the claims). To the extent that any term recited in the claims at the end of this patent is referred to in this patent in a manner consistent with a single meaning, that is done for sake of clarity only so as to not confuse the reader, and it is not intended that such claim term by limited, by implication or otherwise, to that single meaning. Finally, unless a claim element is defined by reciting the word “means” and a function without the recital of any structure, it is not intended that the scope of any claim element be interpreted based on the application of 35 U.S.C. § 112, sixth paragraph.  
         [0014]    [0014]FIGS. 1-3 illustrate an electronic device  100  that has a plurality of operating modes and a corresponding plurality of operable configurations. As shown in FIG. 1, the electronic device  100  may operate as a cellular telephone. Thus, on a face  102  of a first housing member  104  there is disposed a display  106 , a speaker port  108 , a microphone port  109  and a keypad  10 . Secured to the first housing member  104  is an antenna structure  112 . As best viewed in FIG. 2, the electronic device  100  has a second housing member  114  that is hingedly secured to the first housing member  104  along a side  116  of the electronic device  100  by a hinge  134 . The antenna structure  112  has a round housing  118  encompassing the antenna and extending away from the face  112  through a relief  120  formed in the second housing member  114 . Thus, in the configuration of the electronic device  100  illustrated in FIGS. 1-2, the electronic device is and functions as an ordinary cellular telephone.  
         [0015]    Referring to FIG. 3, the electronic device  100  is shown in a second operable configuration. The first and second housing members  104 ,  112  are rotated open along the hinged side  116  to reveal a first inside face  122  formed on the first housing member  104  and a second inside face  124  formed on the second housing member. In the second configuration the electronic device  100  may be operable as an electronic organizer or a wireless email/Internet appliance. Disposed on the first face  122  are a display  126  and a speaker  128 , and disposed on the second face  124  is a keypad  130  and a microphone port  132 . Any suitable display, keypad, microphone and speaker may be employed to enable the electronic device to function in the manner intended for the second configuration.  
         [0016]    [0016]FIG. 4 illustrates the electronic device  100  structure schematically and functional elements in block diagram. The electronic device  100  includes a processor  400  that is coupled to a memory  402 . The processor  400  may contain a control program or the control program may be retained within the memory  402 . The control program directs operation of the processor  402  to control the operation of the electronic device  100  in its various operable configurations. The processor  402  is further coupled to a user interface  406 , such as the display  106 , speaker  108 , microphone  109  and keypad  110  when the electronic device  100  operates in a cellular telephone configuration (FIGS. 1 and 2) and the display  126 , speaker  128 , keypad  130  and microphone  132  when the electronic device operates in an electronic organizer configuration (FIG. 3).  
         [0017]    The electronic device  100  is a wireless device, and as such it includes a radio that includes a receiver  408  couple to the antenna  112  and to the processor  402 , and a transmitter  410  coupled to the processor and via a power amplifier  412  and balun  414  to the antenna  112 . The antenna  112  is further coupled to a conductive metal plate  416  that is secured within the first housing portion  104  near the first face  122 . The first face  122  covers the metal plate  416  such that it is not exposed. In the embodiment of an electronic device shown in FIGS. 1-4, the metal plate  416  is configured to correspond to the shape of the recess  120  formed in the second housing portion  114  adjacent the antenna  112 . The metal plate  416  is coupled by way of an RF connector  418  to the ground side of the antenna feed  420  coupling the balun, and hence the power amplifier  412  and the transmitter  410  to the antenna  112 . As shown in the equivalent circuit for RF operation in FIG. 5, the balun  414  isolates the metal plate  416  from the first housing portion ground structure  500  at the desired operating frequency.  
         [0018]    A second conductive metal plate  424  is secured within the second housing portion  114  near the second face  124 . The second face  124  covers the metal plate  424  such that it is not exposed. The metal plate  424  has a shape complimentary to the shape of metal plate  416  and is situated within the second housing portion adjacent the recess  120  formed therein. An RF connector  426  couples the metal plate  424  to a second housing portion ground structure  428 .  
         [0019]    As depicted in FIGS. 1-3, and without the multi-state ground structure of the electronic device  100  herein described, the contemplated multiple use modes would be incompatible from an antenna perspective. For discussion, the antenna  112  may be a monopole antenna contained with the round housing  118 . The monopole antenna is driven against the ground structure  500  of the first housing portion  104  so that the antenna  112  and its ground/counterpoise structure is out of the user&#39;s hand when the electronic device is in the second operable configuration (FIG. 2). When used as a cellular telephone in the configuration shown in FIG. 1, and without the described multi-state ground structure the first housing portion  104  would see the high antenna counterpoise current, and hence the antenna would experience poor efficiency when used in the presence of the user&#39;s head. It is desirable to have the ground structure  500  within the first housing portion  104  be the primary antenna counterpoise when the electronic device  100  is in the second operable configuration (FIG. 2) and to have the ground structure  428  within the second housing portion  114  be the primary antenna counterpoise when the electronic device  100  is in the first operable configuration (FIG. 1). The multi-state ground structure of the electronic device  100  provides this exactly.  
         [0020]    [0020]FIG. 5 illustrates schematically the effect of providing metal plates  416  and  424  within the first housing portion  104  and the second housing portion  114 , respectively to provide a switch (schematically shown by switch  504  in FIG. 5) between the ground structure  500  and the ground structure  428  depending on the configuration of the electronic device  100 . With the electronic device  100  in the configuration shown in FIG. 1, the metal plates  416  and  424  are in close proximity and act as a large capacitor (schematically shown as capacitor  506  in FIG. 5). The large capacitor  506  has low impedance at RF, and thus couples the second ground structure  428  with the antenna as the primary antenna counterpoise as the result of the relatively high impedance presented by the balun  414  and the ground structure  500  in this configuration. Essentially, the switch  504  is closed. With the electronic device in the second operable configuration shown in FIG. 3, the metal plates  416  and  424  are substantially separated and do not act as a capacitor. There exists high impedance between the antenna  112  and the ground structure  428  relative to the impedance presented by the balun  414  and the ground structure  500 , and the ground structure  500  acts as the primary antenna counterpoise. Essentially, the switch  504  is open. Thus, as can be seen from the embodiments described herein, a ground structure may be switched between multiple states for a given use mode.  
         [0021]    Referring again to FIG. 2, the antenna housing  118  may be configured to house in addition to the antenna  112  a peripheral device. An example of such a peripheral device is a camera  136 . Other peripheral devices may be disposed within the housing  136  such as an infra-red transceiver, an optical scanner, a biometric sensor for identifying a user and the like.  
         [0022]    Still other modifications and alternative embodiments of the invention will be apparent to those skilled in the art in view of the foregoing description. This description is to be construed as illustrative only, and is for the purpose of teaching those skilled in the art the best mode of carrying out the invention. The details of the structure and method may be varied substantially without departing from the spirit of the invention, and the exclusive use of all modifications which come within the scope of the appended claims is reserved.