Abstract:
A computer and a method according to which an assembly is provided for electrostatically moving air for cooling the interior of the computer. The assembly includes an ionization strip for selectively receiving high voltage, such that when the high voltage is applied to the ionization strip, charged air rushes toward a heat sink disposed in the computer, thereby creating an airflow through the heat sink.

Description:
BACKGROUND  
         [0001]    The present disclosure relates, in general, to a computer, or other similar electronic device, and, more particularly, to such a computer and method according to which an assembly is provided for electrostatically moving air for cooling the interior of the computer.  
           [0002]    As computers, such as central processing units, servers, and other similar types of electronic devices, grow in speed and capacity, power consumed within the system per unit volume (power density) increases dramatically. Consequently, each new generation of computer components generates more heat than the previous generation. It is essential to remove such heat from the computer to ensure that the components remain within their normal operating temperature ranges. Otherwise, the components will have a reduced lifetime, or in some cases, will fail immediately.  
           [0003]    In the past, the most popular technique of dissipating heat from a computer has been to provide an internal fan, or fan assembly, to mechanically apply a relatively high-velocity air across the surface of the internal components to cool the components. This raises the convective heat transfer coefficient for the surface of the internal components, thereby increasing the convection cooling.  
           [0004]    Although a fan-based system provides reasonably effective cooling, it has several drawbacks. For example, in relatively large systems, a standard sized fan does not have the capacity to cool the internal components, and so a larger fan, or a series of fans must be used. This takes up valuable space in the computer, and creates greater fan noise. Likewise, forcing the air through the computer causes turbulence, which, as will be described, limits the cooling effectiveness. Finally, the fans have mechanically wearing parts, which are relatively unreliable, considering the importance of their role in cooling the computer.  
           [0005]    Accordingly, what is needed is a computer incorporating a relatively smaller, quieter, and more efficient assembly for cooling the interior of the computer. It has been shown under laboratory conditions that in the same volumetric flow, electrostatic air movement transfers more heat than a mechanical fan (see “Heat Transfer Enhancement in a Convective Field by Applying Ionic Wind,” Tada, Takimoto, and Hayashi; Gordon and Breach Publishing Group; http://www.gbhap.com/fulltext/230/T960100F230.htm). However, until now, the disadvantages associated with electrostatic cooling, such as ozone formation and the required high voltage have discouraged use with computers.  
         SUMMARY  
         [0006]    An embodiment of the present invention is directed to a computer and a method according to which an assembly is provided for electrostatically moving air for cooling the interior of the computer. To this end, a computer includes a heat-producing component in the computer chassis. A heat sink is adjacent the component. An ionization strip is adjacent the heat sink. When high voltage is applied to the strip, charged air rushes toward the heat sink creating a cooling airflow. 
       
    
    
     DESCRIPTION OF THE DRAWINGS  
       [0007]    [0007]FIG. 1 is a diagrammatic view of an embodiment of a computer.  
         [0008]    [0008]FIG. 2 is a schematic view of a cooling assembly for the computer of FIG. 1.  
         [0009]    [0009]FIG. 3 a  is a schematic view of air movement in a heat sink of the cooling assembly of FIG. 2.  
         [0010]    [0010]FIG. 3 b  is a schematic view of forced air movement through a heat sink.  
         [0011]    [0011]FIG. 4 is a top plan view of an ionization strip of the cooling assembly of FIG. 2.  
         [0012]    [0012]FIG. 5 a  is a plan view of one side of the ionization strip of FIG. 4.  
         [0013]    [0013]FIG. 5 b  is a plan view of another side the ionization strip of FIG. 4.  
         [0014]    [0014]FIG. 5 c  is a cross-sectional view of the ionization strip of FIG. 4. 
     
    
     DETAILED DESCRIPTION  
       [0015]    [0015]FIG. 1 illustrates a computer, generally referred to by the reference numeral  10 . The computer is understood to be in the form of a desktop computer, a server, a tower computer, or the like. The computer  10  includes a chassis  12  in which a motherboard  14  is mounted. A processor  16  is connected to the motherboard  14 , and a plurality of memory devices, or modules  18 , and two input/output (I/O) devices  20  are mounted on the motherboard. Two buses  22   a  and  22   b  are also provided on the motherboard  14  and connect the processor  16  to the memory modules  18  and to the input/output devices  20 , respectively.  
         [0016]    A power supply  24  is connected to the motherboard  14 . A pair of cable assemblies  26   a  and  26   b  connect the motherboard to a hard drive unit  28   a  and a disk drive unit  28   b , respectively. It is understood that other components, electrical traces, electrical circuits and related devices (not shown) are provided in the chassis  12 . Because these are all conventional, they will not be described in any further detail.  
         [0017]    Referring now to FIG. 2, a cooling assembly is shown for using electrostatic principles to create air movement through the computer of FIG. 1 for cooling the components, the assembly being generally referred to by the reference numeral  30 . The assembly  30  comprises an electrical connector  32  connecting the power supply (not depicted) to a step-up circuit  34 . The step-up circuit  34  is connected via an electrical connector  36  to a ground  38 . Another electrical connector  40  connects the step-up circuit  34  to an ionization strip  42 .  
         [0018]    As will be explained in greater detail in the description of operation, the ionization strip  42  receives high voltage at the direction of the step-up circuit  34 . The high voltage ionizes the surrounding air, which, as represented by the arrows A 1 , then rushes toward a heat sink  44  across a gap  45 . The distance across gap  45  is dependent on the voltage used, but is a distance beyond where arcing would occur. In one embodiment, the gap distance would be 10% to 20% greater than the distance where arcing would occur. The heat sink may be formed from an aluminum alloy or other conventional heat sink materials. The heat sink  44  is connected to the ground  38  via an electrical connector  46 .  
         [0019]    As mentioned above, ozone (O 3 ) is created when air is ionized. In one embodiment, the surface or channels of the heat sink  44  are coated (painted, sputtered, electro-plated, or annealed) with a catalyst that breaks down ozone created by the ionization of the air, and converts it back to normal oxygen (O 2 ). Examples of such a catalyst are Platinum, Manganese Dioxide, Manganese Oxide, Iodonium, Teledyne WaterPik LTC-95, Engelhard Corp. proprietary catalyst (i.e., U.S. Pat. No. 4,343,776), and Titanium Dioxide, although other ozone decomposing catalysts are contemplated. Some of these catalysts also break down other pollutants found in the air as well. The extent of the decomposition depends on how many ozone molecules come in contact with the catalyst.  
         [0020]    The charged air A 1  enters a plurality of channels  48  formed in the heat sink  44 . The entry of the charged air A 1  into the channels  48  creates a net movement of air, or airflow, denoted A t , through each of the channels  48 . The greater the voltage that is applied to the ionization strip  42 , the more air will be ionized as the charged air A 1 , and thus, the greater the volume of airflow A t  will be created. As such, it can be appreciated that the airflow A t  is directly related to the amount of voltage supplied to the ionization strip  42 , and thus, the step-up circuit  34  indirectly controls the airflow A t .  
         [0021]    It is understood that the heat sink  44  is disposed adjacent to a heat-producing component, such as a processor (not depicted). Heat is transferred from the component to the heat sink  44 , and thence by convection to the airflow A t . Therefore, the air currents exiting the channels  48 , represented by the arrows A 2 , have a higher temperature than the ambient air entering the heat sink  44 . The amount of heat transferred from the heat sink  44 , and hence from the component, can be increased by increasing the airflow A t . For simplicity, this heat transfer process from component to heat sink to airflow is referred to as cooling.  
         [0022]    A thermostat  50  is disposed in the vicinity of the heat sink  44  for determining the temperature of the environment, or ambient air, surrounding the component. The thermostat  50  is connected to the step-up circuit  34  via an electrical connector  52 . Thus, a closed loop is formed between the step-up circuit  34  and the thermostat  50 . As observed above, the amount of airflow A t  can be controlled by changing the voltage supplied to the ionization strip  42  to create more cooling or less cooling.  
         [0023]    In one embodiment, a heat pipe  54  may also be connected to the heat sink  44 . Cooling produced by the removal of heat via airflow A t  in the channel  48  at one end  54   a  of the heat pipe causes heat, represented as phantom arrow B, to be drawn into the distal end  54   b  of the heat pipe. The heat is then exhausted along with the currents A 2 .  
         [0024]    In operation, a high voltage, for example, 1KV to 12KV, is applied to the ionization strip  42  via the electrical connector  40 . The voltage range is found in other consumer electronics devices, such as monitors and televisions, and it is understood that the assembly  30  comprises conventional means for isolating the high voltage that the assembly  30  comprises conventional means for isolating the high voltage discharge from users. The embodiment also contemplates voltages much larger than 12KV, as those voltages can correspondingly increase the airflow.  
         [0025]    Upon reception of the high voltage, the air surrounding the ionization strip  42  is ionized, which can normally be observed as a blue glow. The charged air A 1  then quickly accelerates toward and into the grounded conductive heat sink  44  via electrostatic (ionic) effects. It can be appreciated that the greater the surface area of the ionization strip  42 , the greater the volume of air that will be moved. Likewise, as mentioned above, a greater volume of air can be ionized with a higher voltage.  
         [0026]    The closed loop formed between the step-up circuit  34  and the thermostat  50  can be used to keep the component environment at a relatively constant temperature. For example, if no cooling were needed, no voltage would be supplied to the ionization strip  42  via the step-up circuit  34 . If maximum cooling were needed, the ionization strip  42  would be supplied with as high a voltage as practicable, thus causing the largest amount of air to be ionized and thus maximizing the airflow A t , and hence maximizing the cooling. The ability of the assembly  30  to adjust the voltage to control the airflow A t  has a significant efficiency advantage for reducing power consumption, as can be readily appreciated.  
         [0027]    Referring to FIG. 3 a , the charged air A 1  is illustratively depicted as divided into six exemplary portions, depicted as arrows A 1a-f . By virtue of the charge received from the ionization strip  42 , each of the charged air portions A 1a-f  seeks to ground with the surface defining a channel  48  of the heat sink  44 . This causes great turbulence of air currents, which are depicted with arrows as A c , in the channel  48 . The ionization enables a high percentage of the air currents A c  to contact the surface of the heat sink  44 . This contact results in maximum heat transfer from heat sink to air, and is considerably more efficient at transferring heat into the airflow A t  than traditional fan based techniques, which will be described with respect to FIG. 3 b . The increase in efficiency represented in FIG. 3 a  would enable the use of smaller and lighter weight heat sinks than those presently used in fan cooled computer products, which is advantageous, especially for portable computers.  
         [0028]    Moreover, in the coated heat sink embodiment, almost all of the ozone molecules would connect with the heat sink  44 , and hence the catalyst, meaning that almost all of the ozone will be converted to oxygen (this includes any ozone which existed in the ambient air prior to ionization). Therefore, using the assembly  30  for cooling could result in the air leaving the computer being cleaner than the air going into the computer.  
         [0029]    Referring to FIG. 3 b , as compared to the foregoing, a conventional fan  56  pushes an air current, denoted as C 1 , to a channel  48 ′ of a heat sink  44 ′. The air current C 1  is illustrated as divided into six exemplary portions, depicted as arrows C 1a-f . As will be observed from FIG. 3 b , merely forcing air with a fan does not insure that all molecules of the airflow will make physical contact with the surface of the heat sink. For example, any heat transferred to air currents C 1c  and C 1d  would result from less heat transfer efficient air-to-air contact with turbulent currents C c , and not from direct contact with the wall of the heat sink  44 ′. Thus, relatively less heat is transferred to the airflow, denoted C t , than would be transferred to the airflow A t  (FIG. 3 a ) above. Likewise, if a catalyst were applied to the heat sink  44 ′, the conversion of pollutants would be considerably less efficient, although air leaving the computer would still be cleaner than the air going into the computer.  
         [0030]    As opposed to fan-based cooling systems, the assembly  30  (FIG. 2) provides greater reliability, as there are no moving parts to wear out, and achieves greater efficiency, both thermally and catalytically, using the same volume of airflow. Due to the more efficient heat transfer provided by the assembly  30 , smaller, lower weight, heat sinks may be used. Furthermore, the assembly  30  is not limited to a relatively bulky diameter like a fan, allowing for flatter, thinner, chassis designs. Finally, the assembly  30  provides quieter operation, and the lack of fan noise creates a better user experience. In the coated heat sink embodiment, the assembly  30  even improves air quality in the immediate vicinity of the computer.  
         [0031]    Referring now to FIG. 2 and FIGS.  4 - 5   c , in one embodiment, the ionization strip  42  comprises a plate  60 . The plate  60  is formed from a conductive metal, preferably of a stainless steel, although it is understood that any conductive metal may be used. The plate  60  has a receptacle  62  for receiving the electrical connector  40  (FIG. 2), and consequently, high voltage. The plate  60  has a first edge  64  (FIG. 5 a ), and a second edge  66  (FIG. 5 b ).  
         [0032]    A plurality of spikes  68  protrude from the second edge  66 , terminating in sharp points  70 . As illustrated in FIGS.  4 - 5   c , the remaining edges of the plate  60  are rounded. For reliable operation, it is important that the only sharp edges on the plate  60  are at the points  70  of the spikes  68 , because high voltage ionization will occur along any sharp edges.  
         [0033]    It is understood that in the assembly  30  (FIG. 2), the spikes  68  are directed toward the heat sink  44  (FIG. 2). In one embodiment, the spikes  68  correspond to the channels  48  of the heat sink  44 . It can be appreciated that the gap  45 , FIG. 2, may vary in distance, but must be small enough that the charged air A 1  grounds with the heat sink  44 . Although five spikes  68  are depicted, it is understood that the embodiment contemplates varying numbers of spikes. It can be appreciated that the greater the number of spikes, the more ionization of surrounding air that will occur, and the greater the airflow that will be produced.  
         [0034]    For illustrative purposes, the plate has a length l (FIG. 5 b ), a thickness h (FIG. 5 b ), and a width w (FIG. 4 and  5   c ), the width comprising the plate width a combined with the spike length b. In one example, which is given only for illustrative purposes, and in no way limits the scope of the plate dimensions, the plate  60  has the dimensions listed in Table 1, below.  
                                         TABLE 1                                   Dimension   Inches                                        l   2.75           h   0.0625           w   0.5           a   0.25           b   0.25                      
 
         [0035]    However, it is understood that the plate  60  is contemplated to have many other, different dimensions in addition to those listed in Table  1 , and particularly, that the dimensions are contemplated to vary greatly as the assembly  30  is adapted for use in various sizes and types of computers.  
         [0036]    For example, the ionization strip  42  may comprise an embodiment without spikes (not depicted). This embodiment could take the form of a flat plate with rounded edges on three edges an having a sharpened fourth edge, the plate having a cross section similar to that depicted in FIG. 5 c , but along its entire length. Ionization would occur along the length of the sharpened edge. Similarly, a conductive wire could also be used as the ionization strip  42 , particularly if the wire were flattened on a side to form an edge.  
         [0037]    Likewise, it is understood that all spatial references are for the purpose of example only and are not meant to limit the invention. Furthermore, this disclosure shows and describes illustrative embodiments, however, the disclosure contemplates a wide range of modifications, changes, and substitutions without departing from the scope of the disclosed embodiments. For example, the number of spikes, shape of the ionization strip, and its dimensions can be varied widely.  
         [0038]    Also, the embodiments described above are not limited to the use of a computer in a desktop orientation, but are equally applicable to other types and orientations of the computers, even other electronic components. Other modifications, changes and substitutions are intended in the foregoing disclosure and in some instances some features of the disclosure will be employed without a corresponding use of other features. Accordingly, it is appropriate that the appended claims be construed broadly and in a manner consistent with the scope of the disclosure.