Patent Publication Number: US-9851766-B2

Title: Apparatus and method to efficiently cool a computing device

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of and claims the benefit of priority to previously filed U.S. patent application Ser. No. 14/711,638, filed May 13, 2015, entitled “Apparatus and Method to Efficiently Cool a Computing Device,” which is a divisional of and claims the benefit of priority to previously filed U.S. patent application Ser. No. 11/244,496, filed Sep. 30, 2005, entitled “Apparatus and Method to Efficiently Use Cooling Air”, both of which are incorporated herein by reference in their entirety. 
    
    
     BACKGROUND 
     1. Field 
     The present invention relates to the field of heat management of computing devices, and in particular the cooling of heat generating components and exterior walls of mobile computing devices. 
     2. Discussion of Related Art 
     Heat management can be critical in many applications. Excessive heat can cause damage to or degrade the performance of mechanical, chemical, electric, and other types of devices. Heat management becomes more critical as technology advances and newer devices continue to become smaller and more complex, and as a result run at higher power levels and/or power densities. 
     Modern electronic circuits, because of their high density and small size, often generate a substantial amount of heat. Complex integrated circuits (ICs), especially microprocessors, generate so much heat that they are often unable to operate without some sort of cooling system. Further, even if an IC is able to operate, excess heat can degrade an IC&#39;s performance and can adversely affect its reliability over time. Inadequate cooling can cause problems in central processing units (CPUs) used in personal computers (PCs), which can result in system crashes, lockups, surprise reboots, and other errors. The risk of such problems can become especially acute in the tight confines found inside mobile computers and other portable computing and electronic devices. 
     As the processing powers of mobile computing devices continue to increase, the temperatures of the outer walls of the mobile computing devices will continue to rise to unacceptable levels. The temperatures are becoming the highest within the regions of the memory, central processing unit (CPU), chipset and voltage regulator (VR). To overcome the increase of heat in these locations, vents have been placed in strategic locations to reduce the temperatures. 
     Prior methods for dealing with such cooling problems have included using simple vent systems in the outer walls of a mobile device. But, as the amount of cooling air available within mobile computing devices is reduced as the mobile devices are scaled down, the vent system becomes less and less efficient. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1A  is an illustration of an embodiment of a cross-sectional view of a louvered vent within a mobile computing device. 
         FIGS. 1B-1D  illustrate cross-sectional views of different embodiments of the shape of the louvered vent. 
         FIG. 2A  is an illustration of an overhead view of an embodiment of the inside surface of a wall having a row of louvered vents. 
         FIG. 2B  is an illustration of an overhead view of an embodiment of the outside surface of a wall having a row of louvered vents. 
         FIG. 2C  is an illustration of an overhead view of an embodiment of the outside surface of a wall having a series of rows of louvered vents. 
         FIG. 3A  is an illustration of a cross-sectional view of an embodiment of a nozzle vent within a mobile computing device. 
         FIG. 3B  is an illustration of a cross-sectional view of an embodiment of a manifold of nozzle vents. 
         FIG. 4A  illustrates an embodiment of an inside view of a wall having nozzle vents. 
         FIG. 4B  is an illustration of an embodiment of an outside view of a wall having nozzle vents. 
         FIG. 5  is an illustration of an embodiment of a mobile computing device system that may employ embodiments of louvered vents or nozzle vents to cool the mobile computing device system. 
     
    
    
     DETAILED DESCRIPTION 
     Described herein are methods and devices to decrease the temperatures of the walls of mobile computing devices and of the components within the mobile computing devices. In the following description numerous specific details are set forth. One of ordinary skill in the art, however, will appreciate that these specific details are not necessary to practice embodiments of the invention. While certain exemplary embodiments of the invention are described and shown in the accompanying drawings, it is to be understood that such embodiments are merely illustrative and not restrictive of the current invention, and that this invention is not restricted to the specific constructions and arrangements shown and described because modifications may occur to those ordinarily skilled in the art. In other instances, well known semiconductor fabrication processes, techniques, materials, equipment, etc., have not been set forth in particular detail in order to not unnecessarily obscure embodiments of the present invention. 
     Embodiments disclosed herein include devices to cool the walls of a mobile computing device and to cool the heat generating components of the mobile computing device. In one embodiment, a louvered vent is formed within an external wall of a mobile computing device to create an air curtain between the external wall and a heat generating component to cool the external wall. In another embodiment, a nozzle vent is formed within the external wall of a mobile computing device to flow cooling air at a heat generating component to cool the heat generating component. 
       FIG. 1A  illustrates an embodiment of a louvered vent  110  that has been formed within the external wall  120  of a mobile computing device  100  to form an air curtain  130  between the external wall  120  and a heat generating component  140  to cool the external wall. An air curtain  130  is a thin film of air that is formed along the inside of the external wall  120 . The air curtain  130  is formed inside the mobile computing device  100  to supplement the average airflow  150  available on the inside of the mobile computing device  100 . The air curtain  130  is formed by the fluid dynamics of the louvered vent  110 . The purpose of the air curtain  130  is to isolate the external wall  120  from the heat generating components  140 . The shape of the louvered vent  110  is designed to redirect the flow of the air coming into the mobile computing device  100  from outside of the external wall  120 . The louvered vent  110  illustrated in  FIG. 1A  is a curved louvered vent  110 .  FIGS. 1B, 1C and 1D  illustrate alternative embodiments of the shape of the louvered vent  110 . 
     In  FIG. 1B  an angled louvered vent  110  is illustrated. The angled louvered vent  110  of  FIG. 1B  may have any angle with respect to the external wall  120  that is sufficient to form a curtain of cooling air  130 , but more particularly may have an angle with respect to the external wall  120  in the approximate range of 15 degrees and 45 degrees. 
       FIG. 1C  illustrates a squared of chamber louvered vent  110 . The height  102  of the squared off chamber may vary depending on the dimensions of the interior of the mobile computing device  100 , but in one particular embodiment where the mobile computing device  100  is a laptop computer, the height  102  of the squared off chamber may be in the approximate range of 1 millimeters (mm)-3 mm. The length  104  of the squared off chamber louvered vent  110  may be any length sufficient to form the air curtain  130  along the external wall  120 . 
       FIG. 1D  illustrates a hooded louvered vent  110 . The hooded louvered vent  110  may be curved, angled, or squared and forms an enclosed louvered vent  110  to more specifically focus the air curtain  130 . The hooded louvered vent  110  may have a width and a height sufficient to create an air curtain  130  that is capable of reducing the temperature of the external wall  120 . 
       FIGS. 2A and 2B  illustrate an embodiment of angled louvered vents  110  formed in a row  105  in an external wall  120  of a mobile computing device  100 .  FIG. 2A  illustrates a top view of the inside surface of the external wall  120 . The row  105  of louvered vents  110  is seen in this figure. A row  105  of louvered vents  110  may be used to form many air curtains  130  along the inside surface of the external wall  120 . The multiple air curtains  130  may in effect form a continuous air curtain  130 .  FIG. 2B  illustrates a bottom view of the outside surface of the external wall  120  to illustrate the openings  160  of the louvered vents  110 . In an alternate embodiment, not shown, a louvered vent  110  may be formed that crosses a substantial width or length of the external wall  120 . Many variations of length, width, and positioning of the louvered vents  110  may be used depending on the placement of the heat generating components  140  within the mobile computing device and depending on how many air curtains are sufficient to cool the external wall  120 . 
       FIG. 2C  illustrates an embodiment where a series of rows  105  of louvered vents  110  are positioned to create an air curtain formed of the combined series of air curtains  130  over substantially the entire external wall  120 . The rows  105  of the louvered vents may be positioned approximately 10 mm-30 mm apart. The distance between the rows  105  of louvered vents  110  is determined by the distance at which the air curtain begins to break up so that the next row  105  of louvered vents  110  can take over to form an air curtain over the external wall  120  to cool the external wall  120 . 
     In an embodiment, the positioning of the louvered vents  110  may be determined by the placement of the heat generating components within the mobile computing device  100 . In this embodiment, the louvered vents  110  may be positioned to one side of the heat generating components  140  so that an air curtain  130  is formed substantially beneath the heat generating components  140  as illustrated in  FIG. 1A . The louvered vents  110  described in these embodiments may decrease the temperature of the external wall  120  by approximately 20%-25% or more. The amount by which the temperature of the external wall  120  is decreased may vary depending on the type of louvered vent  110 , the number of louvered vents  110 , and the positioning of the louvered vents  110 . 
     The louvered vents  110  may be formed within the external wall  120  by machining, stamping, or molding, for example. The louvered vents  110  may be formed of any material such as plastic polymers or metal. In one embodiment, the louvered vents  110  are formed of metal and have a length sufficient to provide electromagnetic interference (EMI) shielding. 
       FIG. 3A  illustrates an embodiment of a mobile computing device  300  having a nozzle vent  310 . The mobile computing device  300  has a heat generating component  340  and an external wall  320  near the heat generating component  340 . The nozzle vent  310  is formed within the external wall  320  to flow cooling air at the heat generating component  340 . By directing the flow of the cooling air  305  through the nozzle vent  310 , significant heat transfer rates between the cooling air  305  and the heat generating component  340  can be achieved. Additionally, the use of the available cooling air is maximized. In one embodiment, the center vertical axis  312  of the nozzle vent  310  of  FIG. 3A  may be at a 90 degree angle with respect to the external wall  320  and pointed directly at the heat generating component  340 . In an alternate embodiment, the center vertical axis  312  of the nozzle vent  310  may be angled with respect to the external wall  320 . The angle  315  that is formed between the external wall  320  and the center vertical axis  312  of the nozzle jet may be between approximately 30 degrees and 90 degrees, and more particularly approximately 45 degrees. The nozzle vent  310  may be angled to direct the cooling air  305  at the heat generating component  340  to bring the cooling air  305  into contact with as much surface area of the heat generating component  340  as possible. 
       FIG. 3B  illustrates an embodiment of a mobile computing device  300  where a manifold  350  of nozzle vents  310  is used to distribute the cooling air  305  to specific locations of a heat generating component  340 . The manifold  350  may also be used to direct cooling air  305  to more than one heat generating component  340 . The nozzle vents  310  that are part of the manifold  350  may also be arranged at various angles relative to the external wall  320  to direct the cooling air  305  to strategic locations to maximize the cooling of the heat generating components  340 . 
       FIGS. 4A and 4B  illustrate an embodiment of an external wall  320  of a mobile computing device  300 . The external wall  320  of the  FIGS. 4A and 4B  has two manifolds  350  of nozzle vents  310  and two individual nozzle vents  310 . These figures illustrate a portion of an embodiment of an external wall and are not meant to be limiting in any way.  FIG. 4A  illustrates the inside surface  400  of an external wall  320 . The inside surface of the external wall  320  may have any arrangement of individual nozzles  310  and nozzle manifolds  350  possible, depending on the layout of the heat generating components  340  within the mobile computing device  300 . 
       FIG. 4A  illustrates one example of an outside surface  410  of the external wall  320  having one possible layout of nozzle vents  310 . In one embodiment each of the nozzle vents  310  within the mobile computing device may have the same dimensions. In another embodiment, the dimensions of the nozzle vents  310  within the mobile computing device  300  may vary depending on the size of the heat generating components  340 . The diameter  360  of the openings  365  and the diameter of the base  370  of the nozzle vents  310  may vary depending on the amount of cooling air  305  needed to cool down the heat generating components to a temperature sufficient to prevent the excessive heating of the external wall  320  of the mobile computing device. The diameter  360  of the openings  365  of the nozzle vents  310  and the diameter of the base  370  of the nozzle vents  310  may be varied depending on the size of the heat generating components  340  and the amount of cooling air  305  needed. In one embodiment, the diameter of the openings  365  of the nozzle vents may be in the approximate range of 2 millimeters (mm) and 5 mm and the diameter of the base  370  of the nozzle vents may be in the approximate range of 5 mm and 10 mm. 
     Alternatively a manifold  350  of nozzle vents  310  may be used to provide the necessary amount of cooling air  305 .  FIG. 4A  illustrates two examples of a manifold  350  of nozzle vents  310 . The manifolds  350  may have any number of nozzle vents  310  depending on the size and/or number of heat generating components  340  within the mobile computing device. The dimensions of the nozzle vents  310  that are part of a manifold  350  may be similar or different than the dimensions of the individual nozzle vents  310  on the inside surface of the external wall  320  of a mobile computing device  300 .  FIG. 4B  illustrates the outside of the external wall  320 , illustrating the base openings  375  of the nozzle vents  310  and the manifold openings  380 . In an alternate embodiment, the external wall  320  may further include one or more louvered vents  110  to form an air curtain between the external wall  320  and the heat generating components  340  to create a buffer of cooler air between the external wall  320  and the heat generating component  340 . 
       FIG. 5  illustrates a block diagram of an example computer system that may use an embodiment of the louvered vents  110  or nozzle vents  310  to cool the external walls or heat generating components of a mobile computing device. In one embodiment, computer system  500  comprises a communication mechanism or bus  511  for communicating information, and an integrated circuit component such as a processor  512  coupled with bus  511  for processing information. One or more of the heat generating components or devices in the computer system  500  such as the processor  512  or a chip set  536  may be cooled by an embodiment of the nozzle vents  310  in combination with the louvered vents  110  to cool the external walls of the mobile computing device. 
     Computer system  500  further comprises a random access memory (RAM) or other dynamic storage device  504  (referred to as main memory) coupled to bus  511  for storing information and instructions to be executed by processor  512 . Main memory  504  also may be used for storing temporary variables or other intermediate information during execution of instructions by processor  512 . 
     Firmware  503  may be a combination of software and hardware, such as Electronically Programmable Read-Only Memory (EPROM) that has the operations for the routine recorded on the EPROM. The firmware  503  may embed foundation code, basic input/output system code (BIOS), or other similar code. The firmware  503  may make it possible for the computer system  500  to boot itself. 
     Computer system  500  also comprises a read-only memory (ROM) and/or other static storage device  506  coupled to bus  511  for storing static information and instructions for processor  512 . The static storage device  506  may store OS level and application level software. 
     Computer system  500  may further be coupled to a display device  521 , such as a cathode ray tube (CRT) or liquid crystal display (LCD), coupled to bus  511  for displaying information to a computer user. A chipset, such as chipset  536 , may interface with the display device  521 . 
     An alphanumeric input device (keyboard)  522 , including alphanumeric and other keys, may also be coupled to bus  511  for communicating information and command selections to processor  512 . An additional user input device is cursor control device  523 , such as a mouse, trackball, trackpad, stylus, or cursor direction keys, coupled to bus  511  for communicating direction information and command selections to processor  512 , and for controlling cursor movement on a display device  512 . A chipset, such as chipset  536 , may interface with the input output devices. 
     Another device that may be coupled to bus  511  is a hard copy device  524 , which may be used for printing instructions, data, or other information on a medium such as paper, film, or similar types of media. Furthermore, a sound recording and playback device, such as a speaker and/or microphone (not shown) may optionally be coupled to bus  511  for audio interfacing with computer system  500 . Another device that may be coupled to bus  511  is a wired/wireless communication capability  525 . 
     Computer system  500  has a power supply  528  such as a battery, AC power plug connection and rectifier, etc. 
     Several embodiments of the invention have thus been described. However, those of ordinary skill in the art will recognize that the invention is not limited to the embodiments described, but can be practiced with modification and alteration within the scope and spirit of the appended claims that follow.