Patent Publication Number: US-2007097628-A1

Title: Heat dissipation apparatus for multiple housing devices

Description:
FIELD OF THE INVENTION  
      The present invention relates generally to the field of heat dissipation and in particular to heat dissipation in multiple housing portable devices.  
     BACKGROUND OF THE INVENTION  
      As portable electronic devices incorporate faster microprocessors to accommodate higher data rates, larger displays and the like, heat generated by the electronic components increases also increases. Wireless communication devices, for example, incorporating multimedia functions such as audio streaming, TV broadcast reception and the like will increase the heat generation. This in turn causes the external surfaces of the device to reach uncomfortably warm temperatures, particularly for handheld devices.  
      Many of these portable devices are handheld, foldable clams shell devices wherein most of the heat generating components are housed in one of two or more housings for ease of manufacturing such as to limit the number of connections between multiple housings and the number of circuit boards needed to couple components together. Clam shell devices have the same electronics in general as candy bar from factor devices, however the same components are all or substantially all carried in one of the two housings, i.e. one half the clam shell, resulting in a smaller area carrying the same number of heat generating components. Thus, the smaller surface area increases the external surface temperature even further.  
      Some devices place a fan on the hot component in order to dissipate the heat. For example, fans are placed on some microprocessors in computers to keep the microprocessor cool. This, however, only cools the one component. Additionally, portable devices, handheld in particular, are continuously facing size constraints limiting the internal space for such cooling devices.  
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      The accompanying figures, where like reference numerals refer to identical or functionally similar elements throughout the separate views and which together with the detailed description below are incorporated in and form part of the specification, serve to further illustrate various embodiments and to explain various principles and advantages all in accordance with the present invention.  
       FIG. 1  illustrates a perspective view of an exemplary handheld device.  
       FIG. 2  illustrates an exemplary second housing exploded view of the handheld device.  
       FIG. 3  illustrates an exemplary first housing exploded view of the handheld device.  
       FIG. 4  illustrates an exemplary circuit board that is carried in the housing.  
       FIG. 5  illustrates an exemplary cross section of a housing and fan.  
       FIG. 6  illustrates an exemplary cross section of a housing and fan. 
    
    
      Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of embodiments of the present invention.  
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
      While the present invention is achievable by various forms of embodiment, there is shown in the drawings and described hereinafter several examples of embodiments with the understanding that the present disclosure is to be considered an exemplification of the invention and is not intended to limit the invention to the specific embodiments contained herein as will become more fully apparent from the discussion below. It is further understood that the heat dissipation method and apparatus of the present invention may be used more generally in any application where it is desirable to provide environment control.  
      A handheld device having a means for dissipating heat is disclosed. The device comprises a first housing having a first vent and at least one heat-generating component. The device also comprises a second housing having a second vent and a fan. The first housing is coupled to the second housing by a coupling that provides movement of the first housing and the second housings relative to one another. The coupling has an air flow passage between the first and second housings. The fan of the second housing induces air heated by the at least one heat-generating component to flow from the first housing.  
      Before describing in detail exemplary embodiments that are in accordance with the present invention, it should be observed that the embodiments reside primarily in combinations of components related to heat dissipation. Accordingly, the apparatus components have been represented where appropriate by conventional symbols in the drawings, showing only those specific details that are pertinent to understanding the embodiments of the present invention so as not to obscure the disclosure with details that will be readily apparent to those of ordinary skill in the art having the benefit of the description herein.  
      It is understood that the use of relational terms, if any, such as first and second, top and bottom, and the like are used solely to distinguish one from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. The terms “comprises,” “comprising,” or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. An element proceeded by “comprises . . . a” does not, without more constraints, preclude the existence of additional identical elements in the process, method, article, or apparatus that comprises the element. The terms “a” and “an” mean at least one. The term “exemplary” is intended to mean one example of the invention.  
       FIG. 1  illustrates a perspective view of an exemplary handheld device  100  having a first housing  102  and a second housing  104 . The first housing  102  and the second housing  104  are movably coupled together such that the first housing  102  moves relative to second housing  104 . In this exemplary embodiment, the first housing  102  is coupled by a coupling  106  to the second housing  104 . For example, a hinge, such as an exemplary single axis hinge may movably couple the first housing  102  to the second housing  104 . The first housing has a first housing coupling portion  108 . In this embodiment, the first housing coupling portion  108  comprises two hinge knuckles. The second housing  104  in this embodiment is a flip or cover that rotates about an axis of the coupling  106  from an open to a closed, folded, configuration such that they are stacked adjacently relative to one another. In an alternative embodiment, the first and second housing may slide relative to one another from an open and closed position. The coupling  106  provides movement of the first and second housings relative to one another, and the coupling provides an air flow passage between the first and second housings. The air flow passage extends between the first housing  102  and the second housing  104 .  
      In this exemplary embodiment, the handheld device is a wireless communication device such as a radiotelephone handset. The radiotelephone described herein is a representation of the type of wireless communication device that may benefit from the present invention. However, it is to be understood that the present invention may be applied to any type of multiple housing, hand-held or portable device including, but not limited to, the following devices: radiotelephones, cordless phones, paging devices, personal digital assistants, portable computers, pen-based or keyboard-based handheld devices, remote control units, portable media players (such as an MP3 or DVD player) and the like. Accordingly, any reference herein to the wireless communication device or radiotelephone  100  should also be considered to apply equally to other handheld or portable electronic devices.  
       FIG. 1  illustrates a fan  110 , shown in dotted line format, which is carried in the second housing  104 . The second housing  104  has a vent to allow air to pass between the inside of the housing and the outside. The second housing  104  may have one vent or a plurality of vents. In this exemplary embodiment, the second housing  104  includes a first vent  112 . The fan  110  induces air to flow thought the first vent  112 . The fan  110  is directly coupled or indirectly coupled to the first vent  112 . The position of the vent  112  within the second housing  104  may be located to cause the air to flow through the second housing  104  in a desired direction. For example, the position of the vent  112  in this exemplary embodiment, directs air out of the second housing  104  away from the user when the device is positioned up against the user&#39;s ear.  
      The first housing  102  has a vent to allow air to pass between the inside of the housing and the outside of the housing. The first housing  102  may have one vent or a plurality of vents as with the second housing  104 . In this exemplary embodiment, the first housing  102  carries a plurality of second vents  114 .  
      In this exemplary embodiment, the first vent  112  is an exhaust and the plurality of second vents  114  provide air inlets and therefore air flow is directed from the first housing  102  to the second housing  104 . The fan  110  induces air to enter through the plurality of second vents  114  into the first housing  102 , flow adjacent to the components and through the coupling  106  into the second housing  104  and exit the through the first vent  112 . It is to be understood that the direction of air flow is in this embodiment is one example, and that the air may b directed to flow from the second housing  104  to the first housing  102 . In the exemplary embodiment of  FIG. 1 , the second housing  104  carries the fan  110  and optionally a display  116  or a speaker  118  or both in this embodiment. It is to be understood that other components may be carried in the second housing  104 . Some handheld devices, flip or clamshell type device in particular, generally carry the electronic circuits such as the microprocessor, memory, transmitters and receivers, amplifiers and the like in one housing as they are all connected via a printed circuit board, limiting the number of connections that need to be carried from the first housing  102  to the second housing  104 , and as a result limits the space available in the housing.  
      It is to be understood that one skilled in the art will appreciate that there are many fans and fan modules available. For example, the fan  110  may be a vane axial fan, a radial fan, a mixed flow fan or the like. The fan may be a fan module that comprises a fan blade, a motor and a housing. It is to be understood that there are various way of securing the fan in the housing. For example, the fan may be screwed, glued, press-fit or the like into the second housing  104 . The orientation of the fan within the housing may depend on the amount of space available and the type of fan used. For example, a vane axial fan may be placed so that a long axis of the fan runs from a front to back of the device housing. In another embodiment, the fan may be a radial fan wherein the long axis of the fan may run parallel to the long axis of the device housing. The first housing ( 102 ) and the second housing  104  may have air guides that channel the air flow as induced by the fan  110 . The fan in the second housing ( 104 ), which is the flip housing of the handheld device, directs the airflow, and the heated air away from the user.  
       FIG. 2  illustrates an exemplary second housing exploded view  200  of the handheld device  100 . The second housing  104  is comprised of a body  202 , a first cover  204  and a second cover  206 . The fan  110  is carried on the body  202 . In this embodiment, the fan  110  is carried adjacent to the hinge  106 . The second housing  104  has a second housing coupling portion  208  which couples to the complimentary first housing coupling portion  108 . The second housing coupling portion  208  has an air passage  210  that allows air to move from the first housing  102  to the second housing  104 , in which the air flow is induced by the fan  110 .  
       FIG. 3  illustrates an exemplary first housing exploded view  300  of the handheld device  100 . The exemplary exploded view  300  shows the first housing coupling portion  108  which has a first housing portion air passage  302 . The first housing portion air passage  302  aligns with the second housing air passage  210  to allow air to flow between the first housing  102  and the second housing  104 . The first housing portion air passage  302  enter from the first housing  102  in the direction indicated by arrows  304  and into the second housing air passage indicated by arrow  306 .  
      Also shown in  FIG. 3  are optional air vents. For example, the vents may be positioned between the keys of the keypad creating keypad vents  308  that allow air to flow into the first housing  102  in the direction indicated by arrows  310 . Another alternative location for air vents in the first housing  102  are at the device bottom  312  wherein the device  100  has a connector (not shown). Air flows in the connector vent  314  indicated by the arrow  316 . Yet another alternative location for air vents is a side connector wherein air flows into the side as indicated by arrow  318 . It is to be understood that the locations are exemplary and not independent as all, or any combination of the vents may be present.  
      The fan  110  may also be located in the coupling  106  and not necessarily in the main body of the second housing  104 . The fan  110  may be located in a second housing coupling portion or a first housing coupling portion. For example when the hinge  106  has a first hinge portion coupled to or extending from the first housing  102  that engages a second hinge portion coupled to or extending from the second housing that integrally form the hinge  106 , the fan  110  may be placed in either hinge portion inducing air to flow between the two housings through the hinge.  
       FIG. 4  illustrates an exemplary circuit board  402  that is carried in the first housing  102 . The circuit board  402  carries circuit components  404  wherein at least one of which is a heat generating component  406 . The circuit board  402  dissipates heat from the at least one heat generating component. Air flow, indicated by arrows  408 , over the circuit board  402  and the circuit components  404  provides heat transfer, transporting air heated by the heat generating components, out from the first housing  102  thereby producing a cooling effect.  
      In this embodiment, the air flow direction is such that air enters the first housing  102  though the plurality of second vents  114  therein, and flows adjacent to the circuit board  402  and the circuit components  402 , through the first housing air passage  302  and the second housing air passage  210  of the coupling  106 , and out through the first vent  112  of the second housing  104 . The fan  110  may also be configured to induce airflow in other directions and is not limited to the airflow pattern of this exemplary embodiment. For example, air may enter through the first vent  112  of the second housing  104 , pass through the air passage of the coupling  106 , pass over the circuit components  302  and out through the plurality of second vents  114  in the first housing  102 .  
      The fan  110  may be configured within the second housing  104  in one of many configurations. The fan configuration within the second housing  104  may be a function of the type of fan  110 . In one exemplary embodiment illustrated in  FIG. 5 , a vane-axial fan is shown in a first fan configuration  500 . In this configuration  500 , the fan  110  is positioned such that the direction of air flow is parallel to the axis of rotation  502 . In this embodiment, the air flow is directed towards or away from the hinge  208  depending on the direction of the fan rotation. The position of the fan  110  within the housing  104  may be adjacent to the second housing coupling portion  208  as shown in  FIG. 5 . Alternatively, the fan  110  may be positioned away from the second housing coupling portion  208  or the fan  110  may be positioned within the second housing coupling portion  208 . For example the fan  110  may be positioned in the first housing coupling portion  108 , which is a hinge knuckle in one embodiment, of the hinge or a hinge barrel of the hinge  208  which is the second housing coupling portion in this exemplary embodiment.  
       FIG. 6  illustrates a radial fan in a second fan configuration  600 . In this configuration  600 , the fan  110  is positioned such that the axis of rotation  602  and thereby the air flow is directed into or out of the first cover  204 , the second cover  206  pr both. This configuration is suited for devices with thin housings, such as radiotelephone flips for example, as the short dimension of the fan  110  accommodates the thin housing. The radial fan has an exhaust direction perpendicular to axis of rotation. Therefore in this embodiment, air is drawn into the fan from the first vent  112  and the exhaust is directed toward the hinge inside of the housing.  
      While the preferred embodiments of the invention have been illustrated and described, it is to be understood that the invention is not so limited. Numerous modifications, changes, variations, substitutions and equivalents will occur to those skilled in the art without departing from the spirit and scope of the present invention as defined by the appended claims.