System and method for cooling an electronic device

BACKGROUND

0001The housing of a portable electronic device generally defines a space in which various heat-generating components are contained. The heat-generating components are typically mounted on boards, which are themselves attached to the housing. Larger portable electronic devices, such as, laptops, are known to include conductive or phase change mechanisms, such as, heat pipes, that move heat from the heat-generating components to other locations in the electronic devices for dispersing the heat. The dispersal of heat is often enhanced through use of fans, which are configured to move air for the purpose of dissipating heat from the phase change mechanism or from the heat-generating components themselves. The larger portable electronic devices are often capable of employing heat-generating components having relatively high power densities because they are typically equipped with equipped with sufficiently large batteries to enable the fans to be operational whenever the heat-generating components are in operation.

0002Smaller portable electronic devices, however, are typically not equipped with phase change mechanisms or fans because they often do not include components that generate relatively large amounts of heat. Instead, the heat generated by these components is typically dissipated through the housing of the devices. As the computing power of the smaller portable electronic devices increases, however, conventional techniques for dissipating the heat generated by these components will most likely be inadequate. To dissipate the ever-increasing heat loads, the smaller portable electronic devices are likely to include powered cooling devices, such as fans. However, because the batteries contained in smaller portable electronic devices are relatively small, the additional power requirements of the powered cooling devices will negatively affect the performance of the batteries, thereby negatively affecting the performance of the electronic devices themselves.

0003It would therefore be beneficial to have the ability to cool relatively high power density heat-generating components in relatively small portable electronic devices, while substantially maximizing battery performance.

BRIEF DESCRIPTION OF THE DRAWINGS

0004Features of the present invention will become apparent to those skilled in the art from the following description with reference to the figures, in which:

0005<figref idref="DRAWINGS">FIG. 1</figref> shows a simplified block diagram of a system for cooling an electronic device, according to an embodiment of the invention;

0006<figref idref="DRAWINGS">FIG. 2A</figref> shows a simplified schematic diagram of a front section of an electronic device in which the cooling system depicted in <figref idref="DRAWINGS">FIG. 1</figref> may be implemented, according to an embodiment of the invention;

0007<figref idref="DRAWINGS">FIGS. 2B and 2C</figref>, respectively show cross-sectional side views of the electronic device taken along lines “IIB-IIB” in <figref idref="DRAWINGS">FIG. 2A</figref>, according to embodiments of the invention;

0008<figref idref="DRAWINGS">FIGS. 2D-2F</figref>, respectively, show configurations depicting various manners in which an active cooling device may be implemented to cool a passive cooling device, according to embodiments of the invention; and

0009<figref idref="DRAWINGS">FIG. 3</figref> depicts a flow diagram of a method for cooling an electronic device having at least one heat-generating component, according to an embodiment of the invention.

DETAILED DESCRIPTION

0010For simplicity and illustrative purposes, the present invention is described by referring mainly to an exemplary embodiment thereof. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. It will be apparent however, to one of ordinary skill in the art, that the present invention may be practiced without limitation to these specific details. In other instances, well known methods and structures have not been described in detail so as not to unnecessarily obscure the present invention.

0011Disclosed herein are a method and system for cooling an electronic device and an electronic device having the cooling system. The cooling system includes both a passive cooling device, which does not require electrical energy, and an active cooling device, which requires electrical energy. The cooling system also includes a controller configured to activate the active cooling device after the passive cooling device has absorbed at least some of the heat generated by a heat-generating component of the electronic device. In one example, the controller may activate the active cooling device after a predetermined threshold condition has occurred following an initial cooling of the heat-generating component by the passive cooling device. More particularly, for instance, the controller activate the active cooling device after the controller determines that the ability of the passive cooling device to cool the heat-generating component has substantially expired.

0012Through implementation of the method and system disclosed herein, the amount of power required to adequately cool heat-generating components of electronic devices may substantially be minimized. Therefore, battery performance in portable electronic devices may also be substantially optimized.

0013With reference first to <figref idref="DRAWINGS">FIG. 1</figref>, there is shown a simplified block diagram <b>100</b> of a system <b>102</b> for cooling an electronic device <b>120</b> having one or more heat-generating components <b>122</b>, according to an example. It should be understood that the following description of the block diagram <b>100</b> is but one manner of a variety of different manners in which such a cooling system <b>102</b> may be configured. In addition, it should be understood that the cooling system <b>102</b> may include additional components and that some of the components described herein may be removed and/or modified without departing from the scope of the cooling system <b>102</b>. For instance, the cooling system <b>102</b> may include any reasonably suitable number of input devices, cooling devices, etc., as well as other components, which may be implemented in the operations of the cooling system <b>102</b>. In addition, although not shown, the electronic device <b>120</b> may include additional components, such as, an input, a memory, a display, etc.

0014Generally speaking, the cooling system <b>102</b> is designed and configured to cool one or more heat-generating components <b>122</b>, such as, processors, displays, memories, power supplies, etc., of electronic devices <b>120</b>. More particularly, the cooling system <b>102</b> is configured to substantially minimize the amount of power used in adequately dissipating the heat generated by the one or more heat-generating components <b>122</b>. In one regard, the energy usage is substantially minimized by activating an active cooling device <b>106</b> after a predetermined threshold condition is met, such as, when a passive cooling device <b>104</b> is no longer capable of adequately dissipating the heat generated by the heat-generating component(s) <b>122</b>. The predetermined threshold condition, however, may also be based upon the temperatures of the heat-generating component(s) <b>122</b>, the length of time that the heat-generating component(s) <b>122</b> have been active, etc.

0015As shown in <figref idref="DRAWINGS">FIG. 1</figref>, the cooling system <b>102</b> includes a passive cooling device <b>104</b> and an active cooling device <b>106</b>. The passive cooling device <b>104</b> and the active cooling device <b>106</b> are configured to dissipate heat generated by one or more of the heat-generating components <b>122</b>. The passive cooling device <b>104</b> is configured to dissipate heat generated by the heat-generating component(s) <b>122</b> without requiring electrical power. In this regard, the passive cooling device <b>104</b> may comprise, for instance, a phase change material (“PCM”) that is configured to change phase from a solid to a liquid or from a liquid to a gas at a predetermined temperature.

0016The PCM generally operates to dissipate heat generated by the heat-generating component(s) <b>122</b> by absorbing the heat by changing phase. As such, the ability of the passive cooling device <b>104</b> to cool the heat-generating component(s) <b>122</b> is designed to expire after a predetermined amount of heat is absorbed from the heat-generating component(s) <b>122</b>. In other words, for instance, the materials forming the PCM contained in the passive cooling device <b>104</b> may be selected such that the PCM changes phase at a predicted rate depending upon the amount of heat known to be generated by the heat-generating components(s) <b>122</b>.

0017In addition or alternatively to the PCM, the passive cooling device <b>104</b> may include a heat sink into which cooling fluid is conveyed. The cooling fluid may comprise the PCM or another reasonably suitable material capable of absorbing heat from a heat source, the heat-generating component(s) <b>122</b>, and conveying it to a heat sink. By way of example, the cooling fluid may comprise, a refrigerant, water, water at reduced pressure, Fluourinert™, etc. Again, the ability of the passive cooling device <b>104</b> to cool the heat-generating component(s) <b>122</b> is designed to expire after a predetermined amount of heat has been removed from the heat-generating component(s) <b>122</b>.

0018The active cooling device <b>106</b> generally comprises an electrically-powered cooling mechanism. Examples of suitable active cooling devices <b>106</b> include, for instance, air movers, such as, blowers, fans, vortex generators, etc., refrigeration systems, such as, a solid-state thermoelectric device, etc. In the example where the active cooling device <b>106</b> comprises an air mover, the active cooling device <b>106</b> may be configured and arranged to cool the heat-generating component(s) <b>122</b> directly by causing air to flow over or around the heat-generating component(s) <b>122</b>. In addition, or alternatively, the active cooling device <b>106</b> may be configured and arranged to cool the heat generating component(s) <b>122</b> indirectly by causing air to flow over, for instance, the fins of a heat sink, where the heat sink is configured to receive cooling heated by the heat-generating component(s) <b>122</b>. As a yet further example, the active cooling device <b>106</b> may be configured and arranged to indirectly cool the heat-generating component(s) <b>122</b> by cooling the passive cooling device <b>104</b> either directly or indirectly.

0019In the example where the active cooling device <b>106</b> comprises a refrigeration system, the active cooling device <b>106</b> may include one or more cold plates through which refrigerant flows. The heated refrigerant may be cooled, for instance, through implementation of a condenser, such as, a heat sink having fins, and a fan configured and arranged to dissipate heat from the heat sink. In this example, the cold plate(s) may be attached directly to the heat-generating component(s) <b>122</b> and the refrigerant may absorb the heat generated by the heat-generating component(s) <b>122</b> as it flows through the cold plate(s). In addition, or alternatively, the cold plate(s) may be attached to the passive cooling device <b>104</b>, in which case, the refrigerant may absorb heat from the passive cooling device <b>104</b>.

0020In any of the examples above, the active cooling device <b>106</b> may be controlled by a controller <b>110</b>. The controller <b>110</b> may comprise a computing mechanism, such as, for instance, a microprocessor, a micro-controller, an application specific integrated circuit (ASIC), and the like, configured to perform various processing functions. In addition, or alternatively, the controller <b>110</b> may comprise software operating in any of a number of computing mechanisms, such as a processor of the electronic device <b>120</b>. The controller <b>110</b> may further be configured to perform other processing functions in addition to the cooling function described herein.

0021The controller <b>110</b> may communicate with a memory (not shown) configured to provide storage of software, algorithms, and the like, that provide the functionality of the controller <b>110</b>. The memory may be implemented as a combination of volatile and non-volatile memory, such as DRAM, EEPROM, MRAM, flash memory, and the like. In addition, or alternatively, the memory may comprise a device configured to read from and write to a removable media, such as, a floppy disk, a CD-ROM, a DVD-ROM, or other optical or magnetic media.

0022In any regard, the controller <b>110</b> is programmed to control the active cooling device <b>106</b> to substantially minimize the amount of power the active cooling device <b>106</b> draws from a battery <b>112</b>. More particularly, for instance, the controller <b>110</b> is programmed to enable a sufficient amount of time to pass following a predetermined event before activating the active cooling device <b>106</b>, to thereby provide the passive cooling device <b>104</b> with adequate time to cool the heat-generating component(s) <b>122</b> before electrical energy from the battery <b>112</b> is expended in operating the active cooling device <b>106</b>. The controller <b>110</b> may therefore activate the active cooling device <b>106</b> after a determination that a predetermined threshold condition has occurred, where the predetermined threshold condition is selected to occur after the cooling ability of the passive cooling device <b>104</b> has substantially expired. The terms “substantially expired” is intended to include both instances where the cooling ability is about to expire and where the cooling ability has already expired.

0023The input device <b>114</b> may provide input to the controller <b>110</b>, which the controller <b>110</b> may use in determining when to activate the active cooling device <b>106</b>. The input device <b>114</b> may comprise, for instance, a timer, a temperature sensor, a combination thereof, etc. If the input device <b>114</b> comprises a timer, the timer may become initiated when the electronic device <b>120</b> is activated. By way of example, if the electronic device <b>120</b> comprises a cellular telephone, the timer may become initiated when the electronic device <b>120</b> is turned on, when the electronic device <b>120</b> is employed to place or receive a telephone call or is otherwise taken out of a standby mode, etc.

0024As another example, if the electronic device <b>120</b> comprises a laptop computer, a personal digital assistant, a portable game console, an MP3 player, etc., the timer may become initiated in response to a determination that the activity of the electronic device <b>120</b> has reached or exceeded a predetermined activity level. The predetermined activity level may be defined, for instance, as a level in which the heat-generating component(s) <b>122</b> in the electronic device <b>120</b> are generating sufficient heat to warrant cooling of the heat-generating component(s) <b>122</b> in addition to the cooling afforded by the passive cooling device <b>104</b>.

0025In either example, the timer may be implemented to track the length of time the electronic device <b>120</b> is operated at or beyond a predetermined activity level. The controller <b>110</b> may receive the tracked time and may activate the active cooling device <b>106</b> in response to a predetermined amount of time expiring, as described in greater detail herein below.

0026If the input device <b>114</b> comprises a temperature sensor, the input device <b>114</b> may be configured and arranged to detect the temperatures of one or more heat-generating components <b>122</b>, the temperature of the passive cooling device <b>104</b>, the temperatures of one or more cold plates, etc. In addition, the controller <b>110</b> may receive the detected temperature from the input device <b>114</b> and may control operations of the active cooling device <b>106</b> based upon the detected temperature as described in greater detail herein below.

0027According to an example, the controller <b>110</b> may also be programmed to vary operations of one or more of the heat-generating components <b>122</b> to substantially reduce the amount of power the heat-generating component(s) <b>122</b> draw from the battery <b>112</b>. By way of example, if the heat-generating component <b>122</b> comprises a display, the controller <b>110</b> may automatically reduce the brightness of the display, for instance, once the active cooling device <b>106</b> is activated. In this regard, the controller <b>110</b> may substantially delay or prevent activation of the active cooling device <b>106</b> by reducing the amount of heat generated by the heat-generating component(s) <b>122</b>.

0028With reference now to <figref idref="DRAWINGS">FIG. 2A</figref>, there is shown a simplified schematic diagram of a front section of an electronic device <b>120</b> in which the cooling system <b>102</b> may be implemented, according to an example. It should be understood that the electronic device <b>120</b> may include additional components and that some of the components described herein may be removed and/or modified without departing from the scope of the electronic device. In addition, although particular reference is made to the electronic device <b>120</b> as comprising a cellular telephone, it should be appreciated that the following description of the electronic device <b>120</b> is applicable to various other electronic devices, such as, laptop computers, personal digital assistants, portable game consoles, portable video players, MP3 players, etc.

0029In the example of the electronic device <b>120</b> depicted in <figref idref="DRAWINGS">FIG. 2A</figref>, the electronic device <b>120</b> includes a housing <b>200</b> within which the cooling system <b>102</b> and the heat-generating components <b>122</b> are contained. The electronic device <b>120</b> is also depicted as including a display <b>202</b> and a plurality of input keys <b>204</b>. The display <b>202</b> may comprise a heat-generating component <b>122</b>.

0030Turning now to <figref idref="DRAWINGS">FIG. 2B</figref>, there is shown a cross-sectional side view of the electronic device <b>120</b> taken along lines “IIB-IIB” in <figref idref="DRAWINGS">FIG. 2A</figref>, according to an example. It should be understood that the depiction of the electronic device <b>120</b> is a simplified one and that the electronic device <b>120</b> will include additional features, such as, for instance, a battery, a speaker, interface mechanisms, wires, etc. Accordingly, the electronic device <b>120</b> should not be construed as being limited to the elements depicted in <figref idref="DRAWINGS">FIG. 2B</figref>, but that <figref idref="DRAWINGS">FIG. 2B</figref> merely provides an illustrative example of part of an electronic device <b>120</b> configured to implement the cooling system <b>102</b> disclosed herein.

0031As shown in <figref idref="DRAWINGS">FIG. 2B</figref>, the cooling system <b>102</b> is encapsulated within a housing <b>200</b> of the electronic device <b>120</b>. The cooling system <b>102</b>, more particularly, includes the passive cooling device <b>104</b> and the active cooling device <b>106</b> discussed above with respect to <figref idref="DRAWINGS">FIG. 1</figref>. In addition, <figref idref="DRAWINGS">FIG. 2B</figref> depicts an example of a manner in which the passive cooling device <b>104</b> and the active cooling device <b>106</b> may be integrated with the other components forming the electronic device <b>120</b>.

0032The passive cooling device <b>104</b> is depicted as including a number of separate passive cooling devices <b>210</b>, <b>212</b>, and <b>214</b>. According to an example, the first passive cooling device <b>210</b> generally comprises a phase-change material (PCM) hermetically sealed in an encapsulation. The PCM may comprise a material, such as wax, that is at a solid state at ambient temperatures, but turns into a liquid at relatively higher temperatures. The temperatures at which the PCM changes phase may be controlled by varying the types of materials used to form the PCM. In addition, the encapsulation may be formed of a heat conductive material, such as metallic foil, configured to both hermetically seal the PCM when it is in liquid form and to cause the PCM to return to its original shape when hardening back into solid form.

0033The first passive cooling device <b>210</b> may form the back cover of the electronic device <b>120</b>. In this regard, the first passive cooling device <b>210</b> may readily transfer heat from within the housing of the electronic device <b>120</b> to the environment outside of the housing. It should, however, be understood that the electronic device <b>120</b> may include a back cover to protect the first passive cooling device <b>210</b>, which may be designed to dissipate heat from the first passive cooling device <b>210</b>. In addition, although the first passive cooling device <b>210</b> has been depicted as covering substantially the entire height of the electronic device <b>120</b>, the first passive cooling device <b>210</b> may have a height that is relatively smaller than the electronic device <b>120</b> without departing from a scope of the electronic device <b>120</b> disclosed herein.

0034According to an example, the first passive cooling device <b>210</b> may be readily replaceable. Thus, for instance, once the first passive cooling device <b>210</b> has changed phase from a solid to a liquid and has thus reduced its ability to absorb heat, the first passive cooling device <b>210</b> may be removed to be cooled and may be replaced with another first passive cooling device <b>210</b>.

0035According to a further example, the encapsulation of the first passive cooling device <b>210</b> may be deformable, such that the encapsulation conforms to a user's hand. In this example, for instance, the heat may be dissipated from the first passive cooling device <b>210</b> and into the user's hand. In addition, if the electronic device <b>120</b> includes a back cover, the back cover may comprise a deformable material.

0036As shown in <figref idref="DRAWINGS">FIG. 2B</figref>, the second passive cooling device <b>212</b> is composed of a conduit <b>216</b> and cold plates <b>218</b>, through which the conduit <b>216</b> passes. The second passive cooling device <b>212</b> is also depicted as including a heat sink <b>220</b>, which may be formed of a plurality of fins to thereby increase heat dissipation from the heat sink <b>220</b>. In operation, a cooling fluid or a phase-change material is supplied through the conduit <b>216</b> and absorbs heat from the heat generating components <b>122</b> through the cold plates <b>218</b>.

0037The heat generating components <b>122</b> are depicted as being attached to respective cold plates <b>218</b> with a conductive material <b>222</b>, such as thermally conductive adhesive, paste, strip, etc. Likewise, the cold plates <b>218</b> are depicted as being attached to the first passive cooling device <b>210</b> with a conductive material <b>224</b>, such as, thermally conductive adhesive <b>224</b>. The cold plates <b>218</b> are themselves formed of a thermally conductive material, such as, copper, aluminum, or the like. As such, heat generated by the heat-generating components <b>122</b> may be conducted through the thermally conductive adhesives <b>222</b> and <b>224</b>, and through the cold plates <b>218</b> to be absorbed into the first passive cooling device <b>210</b>.

0038The third passive cooling device <b>214</b> may also include a PCM encapsulated in a heat conductive material, similar to the first passive cooling device <b>210</b>. However, as shown in <figref idref="DRAWINGS">FIG. 2B</figref>, the third passive cooling device <b>214</b> is positioned behind the screen <b>202</b> and may be positioned to absorb heat generated by the display <b>202</b>. The third passive cooling device <b>214</b>, may, alternatively be formed of a thermally conductive material, similar to the cold plates <b>218</b> and the conduit <b>216</b> may be configured to also deliver and remove cooling fluid from the third passive cooling device <b>214</b>.

0039According to another example, the second passive cooling device <b>212</b> may function as part of the active cooling device <b>106</b>. In this example, a pump may be provided to pressurize the cooling fluid contained in the conduit <b>116</b> to thereby cause the cooling fluid to flow through the cold plates <b>218</b> and through the heat sink <b>220</b>, where heat absorbed into the cooling fluid may be dissipated. In addition, the conduit <b>216</b> in this example may be formed into a loop, such that, the cooling fluid may be re-circulated through the cold plates <b>218</b> and the heat sink <b>220</b> to thereby provide substantially continuous cooling to the heat-generating components <b>122</b>.

0040The active cooling device <b>106</b> is depicted as also including a fan <b>230</b> configured and arranged to supply airflow over the heat sink <b>220</b> to thereby substantially enhance dissipation of heat from the heat sink <b>220</b>. More particularly, and as shown, the fan <b>230</b> may be configured to draw air into or out of the housing <b>200</b> through openings <b>232</b>. As such, although the fan <b>230</b> has been positioned to supply air across the heat sink <b>220</b>, the fan <b>230</b> may also be configured to supply airflow over the heat-generating components <b>122</b> to thereby dissipate heat directly from the heat-generating components <b>122</b>.

0041As described in greater detail herein below, the active cooling device <b>106</b> including the fan <b>230</b> and in certain instances, the second passive cooling device <b>212</b>, may be activated according to a control scheme designed to substantially minimize power requirements of the active cooling device <b>106</b>. In this regard, for instance, the fan <b>230</b> may be connected to a circuit board <b>240</b> to which a controller <b>110</b>, which may comprise one of the heat-generating components <b>122</b>, is connected.

0042Turning now to <figref idref="DRAWINGS">FIG. 2C</figref>, there is shown a cross-sectional side view of the electronic device <b>120</b> taken along lines “IIB-IIB” in <figref idref="DRAWINGS">FIG. 2A</figref>, according to another example. As with <figref idref="DRAWINGS">FIG. 2B</figref>, it should be understood that the depiction of the electronic device <b>120</b> is a simplified one and that the electronic device <b>120</b> will include additional features and that the electronic device <b>120</b> should not be construed as being limited to the elements depicted in <figref idref="DRAWINGS">FIG. 2C</figref>. In addition, <figref idref="DRAWINGS">FIG. 2C</figref> contains many of the same features as discussed above with respect to <figref idref="DRAWINGS">FIG. 2B</figref>. As such, only those features that differ from <figref idref="DRAWINGS">FIG. 2B</figref> will be described.

0043The major distinction from <figref idref="DRAWINGS">FIG. 2B</figref> is that the first passive cooling device <b>210</b>′ in <figref idref="DRAWINGS">FIG. 2C</figref> is occupies a relatively larger space in the electronic device <b>120</b>. As shown, the heat-generating components <b>122</b> is surrounded by the PCM of the first passive cooling device <b>210</b>′. In one example, the PCM may be in direct contact with the heat-generating components <b>122</b> and the heat-generating components may therefore be capable of operating when the PCM changes to a liquid state. In another example, an impermeable barrier (not shown) may be positioned between the heat-generating components <b>122</b> and the PCM. In addition, a back cover <b>234</b> may be provided to at least one of hold and protect the components contained in the electronic device <b>120</b>. The back cover <b>234</b> may be rigid or may be flexible as discussed above.

0044Although the active cooling device <b>212</b> has been depicted as being outside of the first passive cooling device <b>210</b>′, the active cooling device <b>212</b> may also be positioned within the first passive cooling device <b>210</b>′. In this example, the first passive cooling device <b>210</b>′ may occupy a substantially larger area within the electronic device <b>120</b>. In addition, the fan <b>230</b> and the heat sink <b>220</b> may be positioned cause air to flow through the electronic device <b>120</b> in a direction that is substantially perpendicular to that shown in <figref idref="DRAWINGS">FIG. 2C</figref>. Alternatively, gaps may be created through the first passive cooling device <b>210</b>′ to enable air to flow through the electronic device <b>120</b>.

0045<figref idref="DRAWINGS">FIGS. 2D-2F</figref> show additional examples of various configurations in which the active cooling device <b>106</b> is configured and arranged to directly cool the passive cooling device <b>104</b>.

0046With reference first to <figref idref="DRAWINGS">FIG. 2D</figref>, there is shown a cross-sectional side view of part of the cooling system <b>102</b> in which the active cooling device <b>106</b> is configured and arranged to cool the PCM contained in the passive cooling device <b>104</b> by cooling an exterior of the passive cooling device <b>104</b>, according to an example. As shown, the active cooling device <b>106</b> includes the conduit <b>216</b>, which is configured to contact a relatively large surface area of the passive cooling device <b>104</b>. As such, the conduit <b>216</b> may have a substantially “S”-shaped configuration. In addition, the conduit <b>216</b> may be arranged, for instance, within an outer casing of the electronic device <b>120</b>.

0047With reference now to <figref idref="DRAWINGS">FIG. 2E</figref>, there is shown a cross-sectional side view of part of the cooling system <b>102</b>, similar to the configuration depicted in <figref idref="DRAWINGS">FIG. 2D</figref>, according to another example. In the cooling system <b>102</b> depicted in <figref idref="DRAWINGS">FIG. 2E</figref>, however, the conduit <b>216</b> of the active cooling device <b>106</b> is depicted as being integrated within the passive cooling device <b>104</b>. As such, the active cooling device <b>106</b> may directly cool, for instance, the PCM contained in the passive cooling device <b>104</b> to thereby return the PCM to a solid form.

0048Turning now to <figref idref="DRAWINGS">FIG. 2F</figref>, there is shown a cross-sectional side view of part of the cooling system <b>102</b>, according to a further example. As shown in <figref idref="DRAWINGS">FIG. 2F</figref>, a plurality of heat-generating components <b>122</b> may be positioned in a stacked arrangement with sections <b>250</b> of the passive cooling device <b>104</b> extending between the heat-generating components <b>122</b>. In this arrangement, the sections <b>250</b> of the passive cooling device <b>104</b> may include openings <b>252</b> extending therethrough to generally enable the heat-generating components <b>122</b> to communicate with each other or through the circuit board <b>240</b>. In addition, at least a portion of the passive cooling device <b>104</b> may be attached to a cold plate <b>218</b> through a thermally conductive adhesive <b>224</b>. As such, the configuration depicted in <figref idref="DRAWINGS">FIG. 2F</figref> generally enables a plurality of heat-generating components <b>122</b>, such as, electronic chips, to be arranged in a relatively high density configuration, while providing sufficient cooling to the heat-generating components <b>122</b> to enable the relatively high density stacked configuration.

0049In any of the examples discussed above with respect to <figref idref="DRAWINGS">FIGS. 2A-2F</figref>, the active cooling device <b>106</b> may include a pump (not shown) configured to cause cooling fluid, such as, water, refrigerant, etc., to travel through the conduit <b>216</b> to absorb heat from either or both of the passive cooling device <b>104</b> and the heat-generating components <b>122</b>. In addition, or alternatively, the active cooling device <b>106</b> may comprise a thermoelectric cooling device.

0050Various manners in which the cooling system <b>102</b> may be implemented will now be described with respect to <figref idref="DRAWINGS">FIG. 3</figref>, which depicts a flow diagram of a method <b>300</b> for cooling an electronic device having at least one heat generating component <b>122</b>, according to an example. It should be understood that the following description of the method <b>300</b> is but one manner of a variety of different manners in which such a method <b>300</b> may be implemented. In addition, it should be understood that the method <b>300</b> may include additional steps and that some of the steps described herein may be removed and/or modified without departing from a scope of the method <b>300</b>.

0051The following description of the method <b>300</b> is described with particular reference to the components depicted in FIGS. <b>1</b> and <b>2</b>A-<b>2</b>F. It should, however, be understood that the method <b>300</b> may be performed by a cooling system whose components differ from or comprise variations of the components depicted in FIGS. <b>1</b> and <b>2</b>A-<b>2</b>F, without departing from a scope of the method <b>300</b>.

0052Generally speaking, the method <b>300</b> may be implemented by a cooling system <b>102</b> housed in an electronic device <b>120</b>, such as a cellular telephone, a laptop computer, a personal digital assistant, a portable game console, an MP3 player, etc. More particularly, for instance, the controller <b>110</b> of the cooling system <b>102</b> may implement the method <b>300</b> to generally minimize the amount of energy the cooling system <b>102</b> uses in cooling the heat-generating components <b>122</b> of the electronic device <b>120</b>.

0053At step <b>302</b>, the controller <b>110</b> may monitor the electronic device <b>120</b> generally or one or more of the heat-generating components <b>122</b> more specifically. The controller <b>110</b> may monitor the activity by, for instance, monitoring the power states of the heat-generating component(s) <b>122</b>, the amount of power the heat-generating component(s) <b>122</b> are consuming, the power states or power consumption rates of the heat-generating component(s) <b>122</b> over time by integrating the area under a curve depicting the power states over time, etc. The power states of the heat-generating component(s) <b>122</b> may comprise the power states specified in the Advanced Configuration and Power Interface (ACPI) specification.

0054In the examples above, the controller <b>110</b> may predict when the PCM of the first passive cooling device <b>210</b> is near its saturation condition based upon the amount of time the heat-generating component(s) <b>122</b> are at a certain power consumption level. In other words, the controller <b>110</b> may calculate the amount of heat energy the PCM has absorbed based upon the amount of power the heat-generating component(s) <b>122</b> has consumed as well as the length of time at which the power was consumed. In addition, the controller <b>110</b> may compare that heat energy level to a predetermined heat energy level that the PCM is designed to absorb prior to becoming saturated. The controller <b>110</b> may moreover predict when saturation of the PCM is likely to occur and may thus control activation of the active cooling device <b>214</b> accordingly.

0055As another example, the controller <b>110</b> may receive information from the input device <b>114</b>, such as, temperature, activation of the heat-generating component(s) <b>122</b>, the lengths of time the heat-generating component(s) <b>122</b> have been active, etc.

0056As indicated at step <b>304</b>, under normal operating conditions, such as, when the passive cooling device <b>104</b> is capable of adequately cooling the heat-generating component(s) <b>122</b>, heat generated by the heat-generating component(s) <b>122</b> is absorbed by the passive cooling device <b>104</b>, to thereby cool the heat-generating component(s) <b>122</b>. As described above, more than one passive cooling device <b>104</b>, such as, the passive cooling devices <b>210</b> and <b>212</b>, may be implemented to dissipate heat generated by the heat-generating component(s) <b>122</b>. While the passive cooling device <b>104</b> is cooling the heat-generating component(s) <b>122</b>, the controller <b>110</b> may determine whether a predetermined threshold condition has occurred, as indicated at step <b>306</b>.

0057The predetermined threshold condition may comprise, for instance, the passage of a predetermined amount of time since the heat-generating component(s) <b>122</b> have been activated, the temperatures of the heat-generating component(s) <b>122</b> reaching a predetermined level, the temperature of the passive cooling device <b>104</b> reaching a predetermined level, etc. In any of the examples above, the predetermined condition may be predicated upon, for instance, the ability of the passive cooling device <b>104</b> to adequately cool the heat-generating component(s) <b>122</b>. By way of example, the predetermined levels may be based upon the amount of time the PCM in the passive cooling device <b>104</b> takes to substantially or completely change phase. In instances where the input device <b>114</b> comprises a temperature sensor, the predetermined level may be determined as having occurred if the temperature rises at a predefined rate, which may be indicative of the PCM being unable to absorb additional heat.

0058As a first example, therefore, where the predetermined threshold condition is the passage of time, the controller <b>110</b> may determine that a predetermined threshold condition has occurred if a predetermined amount of time has elapsed since the heat-generating component(s) <b>122</b> were activated or otherwise began dissipating heat. As another example, where the predetermined threshold condition is temperature, the controller <b>110</b> may determine that a predetermined threshold condition has occurred if the heat-generating component(s) <b>122</b> or the passive cooling device <b>104</b> reaches a predefined temperature, if the rate at which the temperature of the heat-generating component(s) <b>122</b> or the passive cooling device <b>104</b> increases exceeds a predefined rate, etc.

0059If the controller <b>110</b> determines that the predetermined condition has not occurred at step <b>306</b>, the controller <b>110</b> may continue to monitor the activity of the electronic device <b>120</b>/heat-generating component(s) <b>122</b> at step <b>302</b>, which may include enabling the passive cooling device <b>104</b> to continue absorbing heat from the heat-generating component(s) <b>122</b> at step <b>304</b>.

0060If, however, the controller <b>110</b> determines that the predetermined condition has occurred at step <b>306</b>, the controller <b>110</b> may activate the active cooling device <b>106</b> at step <b>308</b> to thereby cool either or both of the heat-generating component(s) <b>122</b> and the passive cooling device <b>104</b>, in one or more various manners as described above. According to another example, the controller <b>110</b> may attempt to delay activation of the active cooling device <b>106</b> at step <b>308</b> by, for instance, substantially balancing performance of the heat-generating component(s) <b>122</b> and the active cooling device <b>106</b>. In other words, the controller <b>110</b> may reduce the amount of heat dissipated by the heat-generating component(s) <b>122</b> by reducing their performance levels. For instance, the controller <b>110</b> may cause a low-resolution video to be displayed instead of a high resolution display, the controller <b>110</b> may reduce or deactivate the display <b>202</b>, etc.

0061According to an example, the controller <b>110</b> may receive instructions from a user regarding the level of heat generated by the heat-generating component(s) <b>122</b>. For instance, the user may select a power conservation mode, in which the controller <b>110</b> deactivates that display <b>202</b> or outputs low-resolution video, etc. The user may also select a high power mode, in which the controller <b>110</b> maximizes performance while sacrificing energy conservation.

0062After activating the active cooling device <b>106</b>, the controller <b>106</b> may continue to monitor the activity level, for instance, by continuing to monitor the information received from the input device <b>114</b>. While monitoring the activity level, the controller <b>110</b> may determine whether the activity level has decreased below a predetermined level at step <b>310</b>. The predetermined level may be based upon, for instance, the temperatures of the heat-generating component(s) <b>122</b>, the temperature of the passive cooling device <b>104</b>, the length of time the active cooling device <b>106</b> has been active, etc. Again, the predetermined level may be predicated upon the ability of the passive cooling device <b>104</b> to adequately dissipate heat generated by the heat-generating component(s) <b>122</b>.

0063If the activity level has not decreased below the predetermined level at step <b>310</b>, the controller <b>110</b> may continue to cool either or both of the heat-generating component(s) <b>122</b> and the passive cooling device <b>104</b> with the active cooling device <b>106</b>. According to an example, the controller <b>110</b> may activate the active cooling device <b>106</b> to its maximum operating level during a first iteration of step <b>306</b>. According to another example, however, the controller <b>110</b> may gradually increase the operating level of the active cooling device <b>106</b>, for instance, as the length of time the heat-generating component(s) <b>122</b> are active. In this example, the controller <b>110</b> may increase the active cooling device <b>106</b> operating level during each iteration of steps <b>308</b> and <b>310</b> until the active cooling device <b>106</b> has reached its maximum operating level or until the heat-generating(s) <b>122</b> become inactive. By way of example, the controller <b>110</b> may operate the fan <b>230</b> at a low level for a predetermined amount of time and may increase the fan <b>230</b> operating level as the heat-generating component(s) <b>122</b> continues to generate heat. The controller <b>110</b> may increase the fan <b>230</b> operating level in either of a continuous or a stepped manner depending upon a configuration of the fan <b>230</b> control system.

0064If one or more attempts at cooling the heat-generating component(s) <b>122</b> are unsuccessful, which may be an indication that the heat-generating component(s) <b>122</b> are operating at relatively high levels, the controller <b>110</b> may initiate a controlled shutdown procedure of the electronic device <b>120</b>. The controlled shutdown procedure may include automatically backing up or saving current settings and then shutting down the electronic device <b>120</b>. As such, the electronic device <b>120</b> may be shutdown in a manner that enables a user to substantially easily restore the settings on the electronic device <b>120</b>.

0065If, however, the activity level has decreased below the predetermined level at step <b>310</b>, the controller <b>110</b> may de-activate the active cooling device <b>106</b>. In addition, the controller <b>110</b> may continuously implement the method <b>300</b> such that the amount of energy required to cool the heat-generating component(s) <b>122</b> may substantially be minimized, while still providing adequate cooling.

0066By way of a particular example in which the electronic device <b>120</b> comprises a cellular telephone, the passive cooling device <b>104</b> may be sufficient to adequately cool the heat-generating component(s) <b>122</b> during short duration calls and the active cooling device <b>106</b> may be used when the calls exceed a predetermined amount of time. As another example, the passive cooling device <b>104</b> may be sufficient to cool the heat-generating component(s) <b>122</b> during calls and texting sessions, however, the active cooling device <b>106</b> may be activated when the cellular telephone is employed to display video. In this regard, the amount of power required from the battery to cool the heat-generating component(s) <b>122</b> may substantially be minimized.

0067Some of the operations set forth in the method <b>300</b> may be contained as a utility, program, or subprogram, in any desired computer accessible medium. In addition, the method <b>300</b> may be embodied by a computer program, which may exist in a variety of forms both active and inactive. For example, it can exist as software program(s) comprised of program instructions in source code, object code, executable code or other formats. Any of the above may be embodied on a computer readable medium, which include storage devices and signals, in compressed or uncompressed form.

0068Exemplary computer readable storage devices include conventional computer system RAM, ROM, EPROM, EEPROM, and magnetic or optical disks or tapes. Exemplary computer readable signals, whether modulated using a carrier or not, are signals that a computer system hosting or running the computer program can be configured to access, including signals downloaded through the Internet or other networks. Concrete examples of the foregoing include distribution of the programs on a CD ROM or via Internet download. In a sense, the Internet itself, as an abstract entity, is a computer readable medium. The same is true of computer networks in general. It is therefore to be understood that any electronic device capable of executing the above-described functions may perform those functions enumerated above.

0069What has been described and illustrated herein is a preferred embodiment of the invention along with some of its variations. The terms, descriptions and figures used herein are set forth by way of illustration only and are not meant as limitations. Those skilled in the art will recognize that many variations are possible within the scope of the invention, which is intended to be defined by the following claims—and their equivalents—in which all terms are meant in their broadest reasonable sense unless otherwise indicated.