Abstract:
A circuit board is mountable inside a case that houses a user interface device, such that the circuit board is proximate to a portion of an external wall of the case. The portion is situated such that when the case is oriented for the user interface device to be in communication with a user, the portion is conveniently between the circuit board and a location outside and relative to the case that is occupyable by an external device operable to communicate with the circuit board.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates to a method of mounting a radio frequency identification (“RFID”) module, for example an RFID coupler or controller combined with an antenna on one or more circuit boards. The method is particularly useful for mounting an RFID module in a general-purpose handheld computer, especially a ruggedized computer, but is not limited to such applications. While the method is particularly useful for mounting RFID modules, it is not limited to such applications and might beneficially be used to mount other types of circuit boards, particularly circuit boards for processing radio frequency signals. 
         [0003]    2. Description of Challenges in the Art 
         [0004]    Mounting a circuit board within a device presents a number of well-known challenges. Desirably, the mounting arrangement will successfully balance a number of requirements. The circuit board and its connection to the device should be able to survive expected hazards, such as impact to the device, particularly in the case of ruggedized devices. The circuit board should be easy to mount and dismount, particularly in the case of circuit boards that will be installed by end-users. The circuit board should be mounted so as to occupy space efficiently, so as not to block airflow or access to other components or connectors. 
         [0005]    All of these challenges are presented by the task of mounting an RFID module, for example within a ruggedized general-purpose handheld computer, to enable the computer to read data from and write data to RFID devices. However, mounting RFID modules presents additional challenges as well. With RFID modules, electromagnetic coupling is a particular concern. It is desirable to mount an RFID module such that:
       the RFID module is not a source of significant electromagnetic interference for other components;   other components are not a source of significant electromagnetic interference for the RFID module; and   there can be a good electromagnetic signal path between the RFID module and external RFID devices it might communicate with.       
 
         [0009]    In the case of RFID modules that communicate with passive RFID tags using a high frequency carrier signal, it is particularly helpful if the RFID module can be positioned close to the RFID tag in order to shorten the electromagnetic signal path and thus significantly reduce the necessary transmission power. 
       SUMMARY OF THE INVENTION 
       [0010]    The present invention is directed to these challenges. 
         [0011]    According to one aspect of the present invention, there is provided a method of mounting a circuit board inside a case adapted to house a user interface device, comprising mounting the circuit board proximate to a portion of an external wall of the case, the portion being situated such that when the case is oriented for the user interface device to be in communication with a user, the portion is conveniently between the circuit board and a location outside and relative to the case that is occupyable by an external device operable to communicate with the circuit board. 
         [0012]    The portion might be the closest wall of the case to the location and might be, for example, on the bottom of the case. The portion might be remote from other components within the case. The circuit board might be mounted on an inside surface of the portion and might even by mounted directly to that inside surface. The portion might include an access panel. 
         [0013]    Should the circuit board be disposed for radio communication with an external device in the location, the shortest or otherwise best communication path between the circuit board and the location might pass through the portion. In one arrangement, the circuit board might be a radio frequency identification module and the external device a radio frequency identification tag. In this vein, the radio frequency identification tag might be passive and the radio frequency identification module might communicate with the radio frequency identification tag using a high frequency carrier signal. 
         [0014]    The method might further include at least one of: (a) framing the circuit board with reinforcing ribs on the inside surface of the access panel; (b) sandwiching a resilient gasket between the access panel and the case; (c) mating at least one of the reinforcing ribs with the gasket; and (d) connecting the access panel to the case with a set of fasteners and complemental couplings that are distributed about the perimeter of the access panel. 
         [0015]    According to another aspect of the present invention, there is provided a method of mounting a circuit board inside a case, comprising mounting the circuit board on an access panel, for example mounting the circuit board directly to an inside surface of the access panel. 
         [0016]    The method might further include: framing the circuit board with reinforcing ribs on the inside surface of the access panel; sandwiching a resilient gasket between the access panel and the case; connecting the access panel to the case with a set of fasteners and complemental couplings that are distributed about the perimeter of the access panel; or mating at least one of the reinforcing ribs with the gasket. 
         [0017]    According to yet another aspect of the present invention, there is provided a method of mounting a circuit board inside a general-purpose handheld computer having a user interface device and a case with an access panel, comprising: (a) mounting the circuit board on the inside surface of the access panel; (b) framing the circuit board with reinforcing ribs on the inside surface of the access panel; (c) sandwiching a resilient gasket between the access panel and the case; and (d) connecting the access panel to the case with a set of fasteners and complemental couplings that are distributed about the perimeter of the access panel. The method might further include mating at least one of the reinforcing ribs with the gasket. 
         [0018]    In one arrangement, the access panel is situated such that when the case is oriented for the user interface device to be in communication with a user, the access panel is conveniently between the circuit board and a location outside and relative to the case that is occupyable by an external device operable to communicate with the circuit board. The access panel might be the closest part of the case to the location and might be, for example, on the bottom of the case. Additionally, the access panel might be remote from other components within the case. 
         [0019]    Where the circuit board is disposed for radio communication with an external device in the location, the shortest or otherwise best communication path between the circuit board and the location might pass through the access panel. For example, the circuit board might be a radio frequency identification module and the external device a radio frequency identification tag. In this vein, the radio frequency identification tag might be passive and the radio frequency identification module might communicate with the radio frequency identification tag using a high frequency carrier signal. 
         [0020]    According to still another aspect of the present invention, there is provided an apparatus for mounting a circuit board inside a case adapted to house a user interface device, comprising means for mounting the circuit board proximate to a portion of an external wall of the case, the portion being situated such that when the case is oriented for the user interface device to be in communication with a user, the portion is conveniently between the circuit board and a location outside and relative to the case that is occupyable by an external device operable to communicate with the circuit board. 
         [0021]    In this regard, the portion might be the closest wall of the case to the location and might in fact be on the bottom of the case. Additionally, the portion might be remote from other components within the case. 
         [0022]    Where the circuit board is disposed for radio communication with an external device in the location, the shortest or otherwise best communication path between the circuit board and the location might pass through the portion. For example, the circuit board might be a radio frequency identification module and the external device a radio frequency identification tag. In this vein, the radio frequency identification tag might be passive and the radio frequency identification module might communicate with the radio frequency identification tag using a high frequency carrier signal. 
         [0023]    The mounting means might include means for mounting the circuit board on an inside surface of the portion, possibly directly to the inside surface of the portion, or perhaps an access panel. 
         [0024]    The apparatus might further include at least one of: (a) means for framing the circuit board with reinforcing ribs on the inside surface of the access panel; (b) means for sandwiching a resilient gasket between the access panel and the case; (c) means for mating at least one of the reinforcing ribs with the gasket; and (d) means for connecting the access panel to the case with a set of fasteners and complemental couplings that are distributed about the perimeter of the access panel. 
         [0025]    According to another aspect of the present invention, there is provided an apparatus for mounting a circuit board inside a case, comprising means for mounting the circuit board on an access panel, perhaps directly to an inside surface of the access panel. 
         [0026]    The apparatus might further include: means for framing the circuit board with reinforcing ribs on the inside surface of the access panel; means for sandwiching a resilient gasket between the access panel and the case; means for connecting the access panel to the case with a set of fasteners and complemental couplings that are distributed about the perimeter of the access panel; or means for mating at least one of the reinforcing ribs with the gasket. 
         [0027]    According to another aspect of the present invention, there is provided an apparatus for mounting a circuit board inside a general-purpose handheld computer having a user interface device and a case with an access panel, comprising: (a) means for mounting the circuit board on the inside surface of the access panel; (b) means for framing the circuit board with reinforcing ribs on the inside surface of the access panel; (c) means for sandwiching a resilient gasket between the access panel and the case; and (d) means for connecting the access panel to the case with a set of fasteners and complemental couplings that are distributed about the perimeter of the access panel. The apparatus might also include means for mating at least one of the reinforcing ribs with the gasket. 
         [0028]    The apparatus might be characterized by the access panel being situated such that when the case is oriented for the user interface device to be in communication with a user, the access panel is conveniently between the circuit board and a location outside and relative to the case that is occupyable by an external device operable to communicate with the circuit board. 
         [0029]    In some arrangements, the access panel might be the closest part of the case to the location or might be on the bottom of the case. The access panel might be remote from other components within the case. 
         [0030]    Where the circuit board is disposed for radio communication with an external device in the location, the shortest or otherwise best communication path between the circuit board and the location might pass through the access panel. In some arrangements, the circuit board might be a radio frequency identification module and the external device a radio frequency identification tag. In this vein, the radio frequency identification tag might be passive and the radio frequency identification module might communicate with the radio frequency identification tag using a high frequency carrier signal. 
         [0031]    According to another aspect of the present invention, there is provided a case adapted to house a user interface device and to retain a circuit board proximate to a portion of its external wall, characterized by the portion being situated such that when the case is oriented for the user interface device to be in communication with a user, the portion is conveniently between the circuit board and a location outside and relative to the case that is occupyable by an external device operable to communicate with the circuit board. The portion might be the closest wall of the case to the location; it might be on the bottom of the case. As well, the portion is remote from other components within the case. 
         [0032]    Where the circuit board is retained in disposition for radio communication with an external device in the location, the shortest or otherwise best communication path between the circuit board and the location might pass through the portion. The circuit board might be, for example, a radio frequency identification module and the external device a radio frequency identification tag. In this vein, the radio frequency identification tag might be passive and the radio frequency identification module might communicate with the radio frequency identification tag using a high frequency carrier signal. 
         [0033]    The portion might be adapted to retain the circuit board proximate an inside surface or to retain the circuit board directly on the inside surface, in either case perhaps an access panel removable from the main body of the case. 
         [0034]    The case might further include: (a) reinforcing ribs on the inside surface of the access panel adapted to frame the circuit board; (b) a resilient gasket insertable between the access panel and the main body of the case; or (c) a set of fasteners and complemental couplings distributed about the perimeter of the access panel adapted to connect the access panel to the main body of the case. Additionally, at least one of the reinforcing ribs might be adapted to mate with the resilient gasket. 
         [0035]    According to still another aspect of the present invention, there is provided an apparatus for mounting a circuit board inside a case having an access in its external wall, comprising an access panel complemental with the access and adapted to retain the circuit board. The access panel might be adapted to retain the circuit board directly on an inside surface or might include reinforcing ribs on its inside surface for framing the circuit board. 
         [0036]    The apparatus might further include a resilient gasket insertable between the access panel and the case, in which case at least one of the reinforcing ribs might mate with the gasket. 
         [0037]    The apparatus might further include a set of fasteners and complemental couplings distributed about the perimeter of the access panel and the access for connecting the access panel to the case. 
         [0038]    According to still another aspect of the present invention, there is provided a general-purpose handheld computer having a user interface device and a case with an access panel, comprising: (a) reinforcing ribs on the inside surface of the access panel for framing a circuit board; (b) a resilient gasket insertable between the access panel and the case; and (d) a set of fasteners and complemental couplings that are distributed about the perimeter of the access panel for connecting the access panel to the case and sandwiching the gasket. At least one of the reinforcing ribs might be adapted to mate with the gasket. 
         [0039]    The apparatus might further include a circuit board adapted to be framed within the reinforcing ribs on the inside surface of the access panel. 
         [0040]    The apparatus might be characterized by the access panel being situated such that when the case is oriented for the user interface device to be in communication with a user, the access panel is conveniently between the circuit board and a location outside and relative to the case that is occupyable by an external device operable to communicate with the circuit board. 
         [0041]    The access panel might be the closest part of the case to the location, for example the access panel might be on the bottom of the case. Perhaps the access panel is remote from other components within the case. 
         [0042]    Where the circuit board is disposed for radio communication with an external device in the location, the shortest or otherwise best communication path between the circuit board and the location might pass through the access panel. For example, the circuit board might be a radio frequency identification module and the external device a radio frequency identification tag. In this vein, the radio frequency identification tag might be passive and the radio frequency identification module might communicate with the radio frequency identification tag using a high frequency carrier signal. 
       DESCRIPTION OF THE INVENTION 
       [0043]    The invention will be more fully illustrated by the following detailed description of non-limiting specific embodiments in conjunction with the accompanying drawing figures. In the figures, similar components and/or features may have the same reference label. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         [0044]      FIG. 1  is a perspective top-left-front view of a ruggedized general-purpose handheld computer; 
           [0045]      FIG. 2  is a perspective bottom-left-back view of the computer of  FIG. 1 , showing an access panel in the bottom surface of the computer; 
           [0046]      FIG. 3  is an exploded perspective top-left-front view of the computer of  FIG. 1 , with the access panel removed; 
           [0047]      FIG. 4  is an exploded perspective bottom-left-back view of the computer of  FIG. 1 , with the access panel removed; 
           [0048]      FIG. 5  is a perspective top-left-front view of the computer of  FIG. 1 , showing the access panel removed from the computer; 
           [0049]      FIG. 6  is a perspective bottom-left-back view of the computer of  FIG. 1 , showing the access panel removed from the computer; 
           [0050]      FIG. 7  is a plan sectional view of the computer of  FIG. 1 , viewed from the cutting plane A-A; 
           [0051]      FIG. 8  is a plan sectional view of the computer of  FIG. 1 , viewed from the cutting plane B-B; 
           [0052]      FIG. 9  is a lateral sectional view of the computer of  FIG. 1 , viewed from the cutting plane C-C; and 
           [0053]      FIG. 10  is an exploded lateral sectional view of the computer of  FIG. 1 , viewed from the cutting plane D-D. 
       
    
    
     DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS  
       [0054]    The invention will now be illustrated by way of explanation of non-limiting specific exemplary embodiments shown in the drawing figures and described in greater detail herein. 
         [0055]      FIG. 1  shows a ruggedized general-purpose handheld computer, generally illustrated at  10 . The computer  10  includes a ruggedized case  12  which protects an input device (here a keypad  14 ), an output device (here a liquid crystal display or LCD  16 ), and a main circuit board  18  (best seen in  FIGS. 4 ,  6 ,  8 ,  9  and  10 ) that provides the functionality of a general-purpose computer, including storage and processing of data and instructions and communication of data and instructions with peripheral devices, including the keypad  14  and the LCD  16 . To better enable communication with peripheral devices, the main circuit board  18  also includes a bus connector  20 , best seen in  FIGS. 8 ,  9  and  10 , to enable connection of a peripheral device to an address bus and/or a data bus (not shown) on the main circuit board  18 . 
         [0056]    The case  12  further includes an access panel  22  on its bottom surface. The panel  22  is secured to the case  12  by a set of fasteners  24 , for example threaded fasteners, generally distributed about its perimeter. As best seen in  FIGS. 4 and 9 , the fasteners  24  engage the case  12  through a set of complemental couplings  26 , for example nuts, attached to or integrated with the case  12 . As best seen in  FIGS. 3 ,  4 ,  5 ,  6 ,  9  and  10 , the case  12  and the panel  22  sandwich between them a resilient dust gasket  28 . As best seen in  FIGS. 3 ,  5 ,  7  and  10 , the panel  22  further includes a set of reinforcing ribs  30 , that desirably mate with the gasket  28  and frame a mounting area  32 , though neither the mating nor the framing need be continuous. 
         [0057]    As best seen in  FIGS. 3 ,  4 ,  5 ,  7 ,  9  and  10 , the computer  10  might also include an RFID module  34  for providing the computer  10  with the ability to read data from and write data to RFID devices (not shown) and to process such data. 
         [0058]    Although the RFID module  34  might be connected directly to the main circuit board  18  at the bus connector  20 , that arrangement could present a number of problems. First, an end-user might damage the main circuit board  18  when trying to insert the RFID module  34  into the bus connector  20  or might at least avoid making the connection for fear of causing such damage. Second, the RFID module  34  might obstruct access to the main circuit board  18 , such that it might be difficult to add other components, for example expansion cards for providing additional functionality or capacity. Third, when transmitting a radio frequency signal to an RFID device, the RFID module  34  is a source of electromagnetic radiation and should therefore be located remote from the main circuit board  18  to reduce interference. Fourth, when communicating with an RFID device, the RFID module  34  needs to be sufficiently close to the RFID device to establish a good radio frequency communication path and sufficiently remote from other components in the computer  10  to avoid interference from their electromagnetic radiation. For reliable communication, the RFID module  34  should be no more than a few inches from an RFID device and so the RFID module  34  should be located close to the wall of the case  12 , most desirably the bottom of the case so that when the RFID module  34  is aimed at an RFID device, the keypad  14  and the LCD  16  face the end-user. 
         [0059]    For the above reasons, it has been found that the inside surface of the access panel  22  is a suitable location to mount the RFID module  34 . The RFID module  34  can be sized and shaped to fit within the mounting area  32  framed by the reinforcing ribs  30 , the ribs helping to retain the RFID module  34  therewithin and providing protection against impact. The RFID module  34  is additionally protected by the resilient dust gasket  28 , which provides shock absorption against impact to the panel  22  and by the set of fasteners  24  and complemental couplings  26 , which are distributed about the perimeter of the panel  22  to better diffuse impact forces throughout to panel  22  and the case  12  as a whole. 
         [0060]    With the RFID module  34  so mounted on the access panel  22 , the bus connector  20  can include, either at manufacture or after-market, a flexible ribbon cable (not shown) or equivalent that an end-user can easily connect to the RFID module  34 , without applying force to the main circuit board  18 . 
         [0061]    Thus, it will be seen from the foregoing embodiments and examples that there has been described an advantageous way to mount a circuit board, and in particular an RFID module  34 , within a case  12 , for example the case  12  of a general-purpose handheld computer  10 . Advantages of the invention can be obtained by singly or in combination:
       mounting a RFID module  34 , directly or indirectly, to the inside surface of an access panel  22  in the case  12 ;   framing the RFID module  34  with reinforcing ribs  30  on the inside surface of the access panel  22 ;   sandwiching a resilient gasket  28  between the access panel  22  and the case  12 ;   connecting the access panel  22  to the case  12  with a set of fasteners  24  and complemental couplings  26  that are distributed about the perimeter of the panel  22 ;   mounting the RFID module  34  proximate to an external wall of the case  12  for shortening the radio frequency signal path to external devices;   mounting the RFID module  34  proximate to that external wall of the case  12 , typically the bottom wall, that in typical operation would provide the shortest or otherwise best radio frequency signal path to external devices when the keypad  14  and LCD  16  face the end-user; and   mounting the RFID module  34  remote from other components, including the main circuit board  18 , to avoid either being a significant source of electromagnetic interference to the other.       
 
         [0069]    While specific embodiments of the invention have been described and illustrated, such embodiments should be considered illustrative of the invention only and not as limiting the invention. It will be understood by those skilled in the art that various changes, modifications and substitutions can be made to the foregoing embodiments without departing from the principle and scope of the invention expressed in the claims made herein. While the invention has been described as having particular application to ruggedized, general-purpose handheld computers and RFID modules, those skilled in the art will recognize that aspects of the invention have wider application, for example for mounting other types of modules and circuit boards and for mounting in other types of devices, such as personal digital assistants, telephones, test equipment, and larger computers, including workstations, desktop computers and laptop computers.