Abstract:
A synthetic jet device includes a housing, a connector within the housing configured to communicate with an exterior power source, driver electronics within the housing, a first membrane within the housing, and a second membrane within the housing.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    The subject matter disclosed herein relates to synthetic jets and more particularly to synthetic jet packaging. 
         [0002]    Microchips, LEDs, radio frequency components, memory chips, and other electronic devices may generate a significant amount of heat during use. These electronic devices should dissipate this energy in order to prevent damage and to extend their useful life. At times, the environment surrounding the electronic devices may be unable to provide the necessary cooling. In situations were the environment is unable to effectively cool, a cooling device may be included. The cooling device may therefore provide the necessary cooling in combination with the environment to extend the life and protect the electronic device. When including a cooling device to assist in heat removal, the cooling device itself may introduce a number of additional design challenges. 
       BRIEF DESCRIPTION OF THE INVENTION 
       [0003]    In one embodiment, a cooling system includes a housing, a connector within the housing capable of communicating with an exterior power source, driver electronics within the housing, and a first membrane within the housing structure, wherein the first membrane is connected to the driver electronics. 
         [0004]    In another embodiment, a synthetic jet device includes a housing, a connector within the housing configured to communicate with an exterior power source, driver electronics within the housing, a first membrane within the housing, and a second membrane within the housing. 
         [0005]    In another embodiment, a cooling device includes a housing, a connector within the housing configured to communicate with an exterior power source, driver electronics within the housing, and a first piezoelectric membrane, a second piezoelectric membrane, wherein the driver electronics is configured to cause motion of the first and second membrane by delivering electricity. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0006]    These and other features, aspects, and advantages of the present invention will become better understood when the following detailed description is read with reference to the accompanying drawings in which like characters represent like parts throughout the drawings, wherein: 
           [0007]      FIG. 1  is a block diagram of a synthetic jet device, in accordance with an embodiment of the invention; 
           [0008]      FIG. 2  is an exemplary synthetic jet compressing/expelling air; 
           [0009]      FIG. 3  is an exemplary synthetic jet expanding/ingesting air; 
           [0010]      FIG. 4  is a perspective view of a synthetic jet device, in accordance with an embodiment of the invention; 
           [0011]      FIG. 5  is a top view of the synthetic jet device in  FIG. 4 , in accordance with an embodiment of the invention; 
           [0012]      FIG. 6  is a perspective view of a synthetic jet device, in accordance with an embodiment of the invention; and 
           [0013]      FIG. 7  is a top view of the synthetic jet device in  FIG. 6 , in accordance with an embodiment of the invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0014]    Embodiments of the invention generally relate to a synthetic jet device for cooling electronic devices. For example, the device may provide convective cooling for microchips, LEDs, heatsinks, radio components, memory chips, etc. As discussed in detail below, the synthetic jet device advantageously combines all components into a single device. Specifically, the synthetic jet device includes a housing with a connector, power electronics, an actuator, and one or more membranes all within the housing. Furthermore, the device advantageously forms multiple synthetic jets by using the surfaces of the housing in combination with the membranes. Thus, the device creates additional synthetic jets without increasing the number of membranes. 
         [0015]    Turning to the figures,  FIG. 1  is a block diagram of a synthetic jet device  10 , in accordance with an embodiment of the invention. The synthetic jet device  10  includes a housing  12 , connector  14 , power electronics  16 , actuator  18 , and membrane  20 . As seen in  FIG. 1  the synthetic jet device advantageously includes the connector  14 , power electronics  16 , actuator  18 , and membrane  20  within housing  12 , thus, creating a self-contained unit. By including, all of these components in a single package the synthetic jet device  10  may advantageously be inserted into an existing system or may be simply removed and replaced when damaged. For example, a system in need of additional cooling may not need a special design to incorporate these components, but instead may provide the necessary power to operate the synthetic jet device  10 . 
         [0016]    During operation, the synthetic jet device  10  receives power from an external source through the connector  14 . The external power supply may provide power in the form of alternating current (A/C) or direct current (D/C). The connector  14  passes this power on to power electronics  16  through an electrical connection  22 . In addition to its function as an electrical connector, the connector  14  may also function as a physical connector. For example, the connector  14  may physically connect and orient the synthetic jet device  10  in a system. Thus, the connector  14  may properly position the synthetic jet device  10  to cool necessary components or locations in a system. Further, the connector  14  may facilitate electrical communication between the power electronics  16  and the system to which it attaches. Alternatively, the synthetic jet device  10  may be powered by a battery (not shown) in place of the connector  14 , such that the power electronics  16  are powered by the battery, rather than an external source. 
         [0017]    The power electronics  16  may be a general purpose integrated circuit or an application specific integrated circuit (ASIC). For example, the power electronics may include an ASIC designed specifically for the operation of the synthetic jet device  10 . During operation, the power electronics  16  control the timing and release of power to an actuator(s)  18  through an electrical connection  24 . For example, during operation, the power electronics  16  may receive signals through the connector  14  indicating that the system, electrical component, etc., needs more or less cooling. Specifically, the power electronics  16  may receive a signal indicating the need for increased cooling. The power electronics  16  may then increase power and/or timing to the actuator  18  for movement of the membrane  20 . Likewise, if less cooling is required the power electronics  16  may slow the timing and/or decrease power to the actuator(s)  18 . 
         [0018]    The actuator  18  may control movement of the membrane  20  in a variety of ways. For example, the actuator  18  may drive the membrane with an electromagnetic actuator, a piezoelectric actuator, a mechanical actuator (i.e., piston), etc. As the actuator  18  drives the membrane  20 , the membrane  20  moves air out of the housing  12  through an aperture  26 . As the air passes out of the housing  12  it creates a cooling convective airflow over a specific location or component in a system. This convective airflow may assist in preventing premature wear, damage, etc. by supporting heat removal. 
         [0019]      FIGS. 2 and 3  illustrate an exemplary synthetic jet  40  compressing/expelling and expanding/ingesting air. As will be appreciated, synthetic jets, such as the synthetic jet  40 , are zero-net-mass flow devices that include a cavity or volume of air  42  enclosed by at least one flexible membrane, and typically at least two flexible membranes  44 , and a small aperture  46  through which air can pass. The membranes  44  deform in a periodic manner causing a corresponding suction and expulsion of air through the aperture  46 . As air flows out of the synthetic jet  40  it impinges on surface  48  were it convectively cools the surface. 
         [0020]    As illustrated in  FIG. 2  the synthetic jet  40  is undergoing a compressing/expelling step. Specifically, the membranes  44  are moving in the direction of arrows  50 . As the membranes  44  move in the direction of the arrows  50  they reduce the volume  42  and create pressure. The increase in pressure creates a pressure differential between air inside the volume  42  and air outside of the aperture  46 . The difference in pressure causes the air  52  to flow out of the volume  42  and into the relatively low-pressure location outside the aperture  46 , until the pressure equalizes. 
         [0021]    In  FIG. 3 , the synthetic jet  40  is undergoing an expanding/ingesting air step. As illustrated, the membranes  44  are moving in the direction of arrows  56 , which increases the volume  42 . The expansion of volume  42  reduces the air pressure in volume  42 , creating an air pressure differential. The difference in pressure between the volume  42  and the air outside of the aperture  46  attracts the relatively high-pressure air  54  to enter the volume  42 , until the pressure equalizes. Once the volume  42  fills with air, the membranes  44  repeat the compressing/expelling step illustrated in  FIG. 2 . 
         [0022]    Accordingly, the synthetic jet  40  imparts a net positive momentum to its external fluid, here ambient air. During each cycle, this momentum manifests as a self-convecting vortex dipole that emanates away from the aperture  46 . The vortex dipole then impinges on the surface  48  to be cooled, i.e., microchips, LEDs, memory chips, etc., disturbing the boundary layer and convecting the heat away from its source. Over steady state conditions, this impingement mechanism develops circulation patterns near the heated component and facilitates mixing between the hot air and ambient fluid. 
         [0023]      FIG. 4  is a perspective view of a synthetic jet device  10 , in accordance with an embodiment of the invention. The synthetic jet device  10  includes a housing  70 , membranes  72 , and connector  74 . As illustrated the housing  70  forms an irregular shape with a generally rectangular portion  76  connected to a generally circular portion  78 . The rectangular portion  76  may advantageously provide sufficient room to include the connector  74  and power electronics (seen in  FIG. 5 ) within the same housing  70  as the membranes  72 . In addition, the housing  70  includes a top section  80  and a bottom section  82 . As illustrated, the top section  80  defines a top surface  84  and a sidewall  86 . The bottom section  82  may likewise define a bottom surface  88  and a sidewall  90 . 
         [0024]    It is the membranes  72  that create the cooling airflow. In the present embodiment, the two membranes  72  advantageously create three synthetic jets  92 ,  94 , and  96 . The first synthetic jet  92  is formed between a membrane  72  and the top section  80  of the housing  70 . The second synthetic jet  94  is formed between the two membranes  72 . The third synthetic jet  96  is formed between a membrane  72  and the bottom section  82  of the housing  70 . Thus, by using the top and bottom sections  80 ,  82  the device  10  creates two additional synthetic jets without additional membranes  72 . In other embodiments, there may be any number of membranes  72 , e.g., 1, 2, 3, 4, 5, 6, 7, etc. In still other embodiments, there may be a stiff disk in-between each of the membranes  72 . For example, a stiff disk may be positioned between membranes  72  in  FIG. 4 . The stiff disk in between membranes  72  may advantageously increase the synthetic jet count from three to four without adding an additional membrane  72 . 
         [0025]    In order to ingest and expel air with membranes  72  the housing  70  defines an aperture  98 . In the present embodiment the aperture  98  is formed in the housing opposite the connector  74 , but in other embodiments may be formed anywhere on the housing  70 . Furthermore, to improve airflow in and out of the housing  70  the sidewalls  86  and  90  may form an angle  100  with the aperture  98 . For example, the sides walls  86  and  90  may form an angle  100  of 0-90 degrees, 15-75 degrees, or 30-60 degrees with respect to the aperture  98 . Accordingly, optimization of the airflow including direction, speed, and volume may occur by changing the angle  100  and the size of aperture  98 . 
         [0026]    Furthermore, the top and bottom surfaces  84  and  88  may include apertures  102  to assist in ingesting and expelling air. The apertures  102  prevent excessive pressure buildup within the housing  70  that may damage the membranes  72  and hinder smooth fluid flow or reduce the performance of the synthetic jet. As illustrated, in  FIG. 4  there are two apertures  102  on the top surface  84 . While not shown in  FIG. 4 , there are similarly two apertures on the bottom surface  88 . In other embodiments, there may be any number of apertures  102 . For example, there may be 0, 1, 2, 3, 4, 5, 10, 15, 20, etc., apertures on the top or bottom surfaces  84  and  88 . Furthermore, and depending on the embodiment, these apertures  102  may form different shapes and occupy different positions on the top and bottom surfaces  84 ,  88 . 
         [0027]    In the present embodiment, the connector  74  is positioned opposite the aperture  98 . In other embodiments the connector may be positioned at different locations on the rectangular portion  76 . For example, the connector may be position at position  104 . The ability to move the connector  74  to different positions facilitates proper orientation of the device  10 . With proper orientation the device  10  may maximize cooling effectiveness. 
         [0028]      FIG. 5  is a top view of the synthetic jet device  10  in  FIG. 4  with the top surface  84  removed, in accordance with an embodiment of the invention. As illustrated, within the housing  70  is the connector  74 , membrane  72 , frame  120 , and power electronics  122 . The connector  74  includes two prongs  124  that conduct power to the power electronics  122  through electrical lines  126 . While in the present embodiment two prongs  124  are shown, other embodiments may include a connector  74  with apertures that receive prongs from the power source. Further, other types of connectors  74  may also be used. 
         [0029]    After passing through the connector  74  the power enters the power electronics  122 . As mentioned above, rectangular portion  76  may advantageously provide space to contain the power electronics  122  and connector  74 . Furthermore, the power electronics  122  may be an ASIC designed specifically for driving the synthetic jet device  10 . For example, the ASIC may time when the membranes  72  flex and how much they flex by controlling the amount and timing of power to the membranes  72 . Thus, the membranes  72  may bend in sync, out of sync, or one membrane may bend more than another membrane  72 , etc. 
         [0030]    As mentioned above, an electromagnetic actuator, a piezoelectric actuator, a mechanical actuator (i.e., piston), etc., may drive the membranes  72 . In the present embodiment, a piezoelectric actuator drives the membrane  72 . For example, the piezoelectric components may be similar to piezoelectric buzzer elements. In particular, the membrane includes a piezoelectric disk  128  connected with glue  130  to a shim (i.e., disk)  132 . Indeed, the glue  130  attaches and holds the piezoelectric disk  128  in position on the shim  132 . Furthermore, the shim  132  is held in place with the elastomeric frame  120 . Thus, the frame  120  permits oscillation of the membrane(s)  72  by suspending the piezoelectric disk  128  and shim  132  within the housing  70 . 
         [0031]    During operation, power exits the power electronics  122  through electrical line  134  and connects to the piezoelectric disk  128  at connection point  136 . In order for current to flow, a ground wire  138  connects to the shim  132  at connection point  140 . As the electricity enters the piezoelectric element  128  it causes the piezoelectric element  128  to expand. The expansion of the piezoelectric element  128  causes the membrane  72  to bend. For example, the piezoelectric element  128  may receive sinusoidal power causing the membrane  72  to bend sinusoidally up and down. This kind of movement causes the membrane(s)  72  to ingest and then expel air out of the housing  70 , thus, providing a cooling airflow. In addition to wires  134  and  138 , the device  10  includes wires  142  and  144 . While not shown, the wires  142  and  144  connect to the other membrane  72  providing power to the other piezoelectric disk. As explained above, in other embodiments there may be more than two membranes  72 . Each of these membranes requires power and as a result there may be an additional two wires exiting the power electronics  122  for each additional membrane  72 . 
         [0032]      FIG. 6  is a perspective view of a synthetic jet device  10 , in accordance with an embodiment of the invention. The synthetic jet device  10  includes a housing  160 , membranes  162 , and connector  164 . As illustrated, the housing  160  forms an irregular shape with a generally rectangular shape with rounded corners  166 . The housing  160  may advantageously provide sufficient room to include the connector  164  and power electronics (seen in  FIG. 7 ) within the same housing  160  as the membranes  162 . In addition, the housing  160  includes a top section  168  and a bottom section  170 . As illustrated, the top section  168  defines a top surface  172  and a sidewall  174 . The bottom section  170  may likewise define a bottom surface  176  and a sidewall  178 . 
         [0033]    Similar to the device described in  FIG. 4 , the device  10  of  FIG. 6  creates a cooling airflow with membranes  162 . Specifically, the two membranes  162  advantageously create three synthetic jets  180 ,  182 , and  184 . As explained above, by using the top and bottom sections  168 ,  170 , the device  10  creates two additional synthetic jets without additional membranes  162 . In other embodiments, there may be any number of membranes  162 , e.g., 1, 2, 3, 4, 5, 6, 7, etc. In still other embodiments, there may be a stiff disk in-between each of the membranes  162 . For example, a stiff disk may be positioned between membranes  162 . The stiff disk positioned between membranes  162  may advantageously increase the number of synthetic jets from three to four. 
         [0034]    In order to ingest and expel air with membranes  162  the housing  160  defines an aperture  186 . In the present embodiment the aperture  186  is formed in-between the rounded corners  166 , but in other embodiments may be formed anywhere on the housing  160 . Furthermore, to direct or improve airflow in and out of the housing  160  the sidewalls  174  and  178  may form an angle  188  with the aperture  186 . For example, the sides walls  174  and  178  may form an angle of 0-90 degrees, 15-75 degrees, or 30-60 degrees with respect to the aperture  186 . Accordingly, optimization of the airflow direction, speed, and volume may occur by changing the angle  188  and the size of aperture  186 . 
         [0035]    The housing  160  may also include apertures  190  on the top and bottom surfaces  172  and  176 . The apertures  190  may prevent excessive pressure buildup within the housing  160  that may cause damage to the membranes  162  and hinder smooth fluid flow. As illustrated, in  FIG. 6  there are two apertures  190  on the top surface. While not shown in  FIG. 6  there are similarly two apertures  190  on the bottom surface  176 . Moreover, while  FIG. 6  only illustrates two apertures  190 , other embodiments may include any number of apertures  190 . For example, there may be 0, 1, 2, 3, 4, 5, 10, 15, 20, etc., apertures on the top or bottom surfaces  172  and  176 . Depending on the embodiment, these apertures  190  may form different shapes and occupy different positions on the top and bottom surfaces  172 ,  176 . For example, the apertures  190  may be square-like, rectangular, oval-like, etc. 
         [0036]    In the present embodiment, the connector  164  includes two ports  192  instead of two prongs. Similar to the discussion above, and depending on the embodiment, the connector  164  may include ports, prongs, a ribbon connector, etc. Furthermore, the connector  164  may be positioned at different locations on the rectangular portion  160 . The ability to move the connector  164  to different positions facilitates placement and orientation of the device  10 . By properly orienting the device  10 , cooling effectiveness may improve. 
         [0037]      FIG. 7  is a top view of the synthetic jet device  10  in  FIG. 6  without the top section  168 , wherein the in accordance with an embodiment of the invention. As illustrated, the device  10  advantageously includes the connector  164 , membrane  162 , frame  200 , and power electronics  202  all within the housing  160 . 
         [0038]    The device  10  receives power through the connector  164 . The power may be supplied by an A/C or D/C source. The power travels along lines  204  to the power electronics  202 . As mentioned above, housing  160  may advantageously provide space to contain the power electronics  202  and connector  164 . Like the power electronics  122  of  FIG. 5 , the power electronics  202  may be an ASIC designed specifically for driving the synthetic jet device  10 . For example, the ASIC may time when the membranes  162  flex and how much they flex by controlling the amount and timing of power to the membranes  162 . Thus, the power electronics  202  may optimize the cooling flow while simultaneously saving power. 
         [0039]    As discussed above, an electromagnetic actuator, a piezoelectric actuator, a mechanical actuator (i.e., piston), etc., may drive the membranes  162 . In the present embodiment, a piezoelectric actuator drives the membrane  162 . As illustrated, the membrane  162  includes a piezoelectric disk  206  that connects with glue  208  to a shim (i.e., disk)  210 . More specifically, the glue  208  attaches and holds the piezoelectric disk  206  in place on the shim  210 . Furthermore, the shim  210  is held in place with the elastomeric frame  200 . Thus, the frame  200  suspends the piezoelectric disk  206  and shim  210  within the housing  160 . Accordingly, because of the suspension, the piezoelectric disk  206  is able to oscillate within the housing  160 . 
         [0040]    During operation, power travels through the power electronics  202  and power line  212  and into the piezoelectric disk  206  at connection point  214 . In order for current to flow, a ground wire  216  connects to the shim  210  at connection point  218 . As the electricity enters the piezoelectric element  206  it causes the piezoelectric element  206  to expand, and when the power stops it contracts. Thus, by expanding and contracting the piezoelectric element  206  the overall membrane  162  bends. For example, the piezoelectric element  206  may receive sinusoidal power causing the membrane  162  to bend sinusoidally up and down. This kind of movement causes the membrane(s)  162  to ingest and then expel air out of the housing  160 . In addition to wires  212  and  216 , the device  10  includes wires  220  and  222 . While not shown, the wires  220  and  222  connect to the other membrane  162  providing power to another piezoelectric disk (seen in  FIG. 6 ). In embodiments that include more than two membranes  162  there may be additional wires that connect the membranes  162  to the power electronics  202 . 
         [0041]    Technical effects of the invention include combining a connector, membranes, and power electronics, within a single housing. Accordingly, the device may cool an existing system, preventing the redesign of the system to include synthetic jets. Furthermore, because the device includes all the components within a single housing, it may be easily replaced when broken or used. Finally, the device advantageously uses the housing surfaces in combination with the membranes to form additional synthetic jets. 
         [0042]    This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.