Patent Application
20110174468
The embodiments of the present invention are related to ion wind fans, and in particular to a collector electrode for an ion wind fan.
It is well known that heat can be a problem in many electronics device environments, and that overheating can lead to failure of components such as integrated circuits (e.g. a central processing unit (CPU) of a computer) and other electronic components. Most electronics devices, from LED lighting to computers and entertainment devices, implements some form of thermal management to remove excess heat.
Heat sinks are a common passive tool used for thermal management. Heat sinks use conduction and convection to dissipate heat and thermally manage the heat-producing component. To increase the heat dissipation of a heat sink, a conventional rotary fan or blower fan has been used to move air across the surface of the heat sink, referred to generally as forced convection. Conventional fans have many disadvantages when used in consumer electronics products, such as noise, weight, size, and reliability caused by the failure of moving parts and bearings.
A solid-state fan using ionic wind to move air addresses the disadvantages of conventional fans. However, providing an ion wind fan that meets the requirements of consumer electronics devices presents numerous challenges not addressed by any currently existing ionic wind device. For example, ozone (O3) generated by an ion wind fan may need to be mitigated.
Ozone is a pollutant produced by ionic fans. It can cause some adverse health effects and is regulated by numerous government agencies. In addition, ozone has a strong odor that is considered unpleasant at any but the lowest concentration. At very low concentrations, however, ozone is either undetectable by humans or may give the sense of a “fresh and clean” environment.
Ozone produced by an ionic fan can be removed by a catalysis reaction. A common catalyst is Manganese Oxide (MnO), but other known catalysts exist, such as Platinum, Manganese Dioxide, Iodonium, and Titanium Dioxide. When ozone contacts the catalyst it is converted back into normal oxygen (02).
The present invention will now be described in detail with reference to the drawings, which are provided as illustrative examples of the invention so as to enable those skilled in the art to practice the invention. Notably, the figures and examples below are not meant to limit the scope of the present invention to a single embodiment, but other embodiments are possible by way of interchange of some or all of the described or illustrated elements. Moreover, where certain elements of the present invention can be partially or fully implemented using known components, only those portions of such known components that are necessary for an understanding of the present invention will be described, and detailed descriptions of other portions of such known components will be omitted so as not to obscure the invention. In the present specification, an embodiment showing a singular component should not necessarily be so limited; rather the principles thereof can be extended to other embodiments including a plurality of the same component, and vice-versa, unless explicitly stated otherwise herein. Moreover, applicants do not intend for any term in the specification or claims to be ascribed an uncommon or special meaning unless explicitly set forth as such. Further, the present invention encompasses present and future known equivalents to the known components referred to herein by way of illustration.
Ion wind or corona wind generally refers to the gas flow that is established between two electrodes, one sharp and the other blunt, when a high voltage is applied between the electrodes. The air is partially ionized in the region of high electric field near the sharp electrode. The ions that are attracted to the more distant blunt electrode collide with neutral (uncharged) molecules en route to the collector electrode and create a pumping action resulting in air movement. The high voltage sharp electrode is generally referred to as the emitter electrode or corona electrode, and the grounded blunt electrode is generally referred to as the counter electrode, getter electrode, or collector electrode.
The general concept of ion wind—also sometimes referred to as ionic wind and corona wind even though these concepts are not entirely synonymous—has been known for some time. For example, U.S. Pat. No. 4,210,847 to Shannon, et al., dated Jul. 1, 1980, titled “Electric Wind Generator” describes a corona wind device using a needle as the sharp corona electrode and a mesh screen as the blunt collector electrode. The concept of ion wind has been implemented in relatively large-scale air filtration devices, such as the Sharper Image Ionic Breeze.
An electronic device may need thermal management for an integrated circuit—such as a chip or a processor—that produces heat, or some other heat source, such as a light emitting diode (LED). Some example systems that can use an ion wind fan for thermal management include computers, laptops, gaming devices, projectors, television sets, set-top boxes, servers, NAS devices, memory devices, LED lighting devices, LED display devices, smart-phones, music players and other mobile devices, and generally any device having a heat source requiring thermal management.
The electronic device can have a system power supply 16 or can receive power directly from the mains AC via a wall outlet, Edison socket, or other outlet type. For example, in the case of a laptop computer, the laptop will have a system power supply such as a battery that provides electric power to the electronic components of the laptop. In the case of a wall-plug device such as a gaming device, television set, or LED lighting solution (lamp or bulb), the system power supply 16 will receive the 110V mains AC (in the U.S.A, 220V in the EU) current from an electrical outlet or socket.
The system power supply 16 for such a plug or screw-in device will also convert the mains AC into the appropriate voltage and type of current needed by the device (e.g., 20-50V DC for an LED lamp). While the system power supply 16 is shown as separate from the IWFPS 20, in some embodiments, one power supply can provide the appropriate voltage to both an ion wind fan 10 and other components of the electronic device. For example, a single driver can be design to drive the LEDs of and LED lamp and an ion wind fan included in the LED lamp.
The electronic device also includes a heat source (not shown), and may also include a passive thermal management element, such as a heat sink (also not shown). To assist in heat transfer, an ion wind fan 10 is provided in the system to help move air across the surface of the heat source or the heat sink, or just to generally circulate air (or some other gas) inside the device. In prior art systems, conventional rotary fans with rotating fan blades have been used for this purpose.
As discussed above, the ion wind fan 10 operates by creating a high electric field around one or more emitter electrodes 12 resulting in the generation of ions, which are then attracted to a collector electrode 14. In
Similarly, the collector electrode 14 is shown simply as a plate in
To create the high electric field necessary for ion generation, the ion wind fan 10 is connected to an ion wind power supply 20. The ion wind power supply 20 is a high-voltage power supply that can apply a high voltage potential across the emitter electrodes 12 and the collector electrode 14. The ion wind fan power supply 20 (hereinafter sometimes referred to as “IWFPS”) is electrically coupled to and receives electrical power from the system power supply 16. Usually for electronic devices, the system power supply 16 provides low-voltage direct current (DC) power. For example, a laptop computer system power supply would likely output approximately 5-12V DC, while the power supply for an LED light fixture would likely output approximately 20-70V DC.
The high voltage DC generated by the IWFPS 20 is then electrically coupled to the emitter electrodes 12 of the ion wind fan 10 via a lead wire 17. The collector electrode 14 is connected back to the IWFPS 20 via return/ground wire 18, to ground the collector electrode 14 thereby creating a high voltage potential across the emitters 12 and the collector 14 electrodes. The return wire 18 can be connected to a system, local, or absolute high-voltage ground using conventional techniques.
While the system shown in and described with reference to
The IWFPS 20 may include other components. Furthermore, in some embodiments, some of the components listed above may be omitted or replaced by similar or equivalent circuits. For example, the IWFPS 20 is described only as an example. Many different kinds and types of power supplies can be used as the IWFPS 20, including power supplies that do not have a transformers or other components shown in
An example of an ion wind fan is now described with reference to
The collector electrode 32 and the emitter electrodes 36 are both supported by an isolator 34. The isolator is made of a dielectric material, such as plastic, ceramic, and the like. The “isolator” component is thusly named as it functions to electrically isolate the emitter electrodes 36 from the collector electrode 32, and to physically support these electrodes. As such the isolator also can establish the spatial relationship between the electrodes, sometimes referred to under the rubric of electrode geometry. The isolator 34 can be made from one integral piece—as shown in FIG. 2A—or it can be made of multiple parts and pieces.
In the embodiment shown in
The ion wind fan 30—in the embodiment shown in FIG. 2A—is substantially rectangular in top view. The longitudinal axis of the ion wind fan 30 is denoted with the dotted arrow labeled “A.” The ion wind fan 30 has two ends opposite each other along the longitudinal axis. The emitter electrodes 36 are suspended between the two ends of the ion wind fan 30.
In one embodiment, the emitter electrodes 36 are supported at the ends of the ion wind fan 30 by an emitter support 38 portion of the isolator 34. The emitter support 38a at the left end of the ion wind fan 30 is most visible in
In the embodiment shown in
Thus, while in one embodiment the emitter support 38a is a substantially rectangular solid portion of the isolator 34 that connects the two elongated side portions of the isolator 34, in other embodiments the emitter supports 38 can have many other shapes and orientations. For example, a part of the center portion of the emitter support 38a between the emitter electrodes 36 could be cut away without substantially affecting the function of the emitter support 38a.
The emitter support 38a is shown as extending to the end of the ion wind fan 30. However, in other embodiments, the emitter support 38a can end before the end of the ion wind fan 30. The emitter support 38a is also shown as having a curved section at its outside edge to smooth out the 90 degree bend in the wire emitter electrodes 36. This is an optional feature not related to the embodiments of the present invention described herein.
Indeed, the actual attachment of the emitter electrodes 36 to either the emitter support 38 or some other portion of the isolator 34 is not material to the embodiments of the present invention, and therefore will not be discussed in much detail for simplicity and ease of understanding. The emitter electrodes 36 are shown as extending downward from the left end of the ion wind fan 30 and they are connected to the power supply via some wire or bus, as is the collector electrode 32. The emitter supports 38 need not have any particular shape of contact with the emitter electrodes 36. The emitter supports 38 are the portions of the isolator 34 that define the physical spatial relationship between the emitter electrodes 34 and other components of the ion wind fan 30. How exactly the emitter supports 38 are in contact with the emitter electrodes 36 (grooves, stakes, friction, posts, welding, epoxy) are not germane to the embodiments of the present invention.
Though wire sag and other emitter irregularities will create some variance, in one embodiment the air gap 39 between the emitter electrodes 36 and the bottom plane of the collector electrode 32 is substantially constant (within a 5% variation). In other embodiments, the air gap 39 can be more variable. The size of the air gap 39 is dependent on the spatial relationship between the electrodes established by the emitter supports 38 (which are not visible in
In one embodiment of the present invention, the catalyst is only placed in areas of maximum ozone production and concentration. The catalyst has a cost associated with it for the expensive material used, and for the decreased heat dissipation of the heat sink where it is coated with the catalyst. One theoretical reaction model developed by the Applicants predicts that Ozone is highly concentrated downstream of the corona electrodes of the EHD fan. Thus, according to one embodiment—as shown in FIG. 4—special catalyst coated fins are added to a heat sink at a location directly downstream of each corona electrode. For example, in the case of a wire-type corona electrode, the high concentration region will be a long, thin-sheet-like region in the wake of the corona electrode. A catalyst coated fin in this region is predicted to remove ozone at a greater rate at than any other location. Conventional heat sinks do not generally employ horizontal fins not in this manner, as they are not the most efficient configuration for heat dissipation.
Additional fins can be added to conduct/convect heat in any direction. In one embodiment—such as the example shown in FIG. 5—the additional fins can also be coated with the catalyst, to further increase the Ozone removal capacity of the heatsink. The system removes ozone more efficiently than a system without specially located fins. The improved ozone destruction occurs without substantially increasing the flow resistance or impacting the heat transfer rate of the cooling system. In one embodiment, shown in
The rate of ozone production in an EHD fan is reduced at elevated temperatures. If the air were pre-heated prior to reaching the EHD fan, then the EHD fan will produce less ozone. Less ozone production in the fan means less ozone to remove at the catalyst-coated downstream heat sink. In one embodiment, as shown in
An embodiment that improves the ozone catalyzing effectiveness of the fins is shown in 9A. In this embodiment the fins downstream are offset from the fins upstream. This breaks up the boundary layer and puts the ozone in more intimate contact with the catalyst. The staggered fins will also improve the heat dissipation of the heat sink. However, this embodiment exhibits a higher flow resistance and requires additional pumping energy.
An embodiment that increases the total surface area of fins is shown in 9B. In this embodiment additional fins are placed in between a “normal” finned heat sink. The extra surface area will catalyze more ozone. However, like the previous embodiment, it will have a higher resistance to flow.
Another embodiment, shown in
A typical cooling system is located within an enclosure of some type, example: inside the case of a laptop computer or inside some other electronics consumer device, such as an LED light bulb or other lighting device. An embodiment is shown in
Ozone destruction is limited by the surface area coated with the catalyst. Prior art heat sinks are generally constructed as a fin-stack of planar fins, such as the fin shown in
Such a straight-finned heat sink—as shown in FIG. 8A—designed only for heat transfer has a limited amount of surface area for ozone catalysis for the volume of the heat sink. Thus, in one embodiment of the present invention, additional surface area can be incorporated into the same volume by contouring the fins. For example,
In one embodiment, a heat sink can be created by stacking multiple contoured heat sink fins having the shape shown in
In yet another embodiment, as shown in
In one embodiment, a heat sink can be created by stacking multiple contoured heat sink fins having the shape shown in
In yet another embodiment, the fins have a wavelike profile, thus increasing surface area. Such fins can be arranged to form teardrop shaped channels if stacked in opposing facing rows, as explained above. Many additional shapes, contours, and channel geometries are possible.
While the heat sinks shown in
While the example ion wind fan described and pictured above are shown as having two emitter electrodes, any number of emitter electrodes can be used, including one, to create one or more-channel ion wind fans. While most electronics cooling applications using a wire emitter will have between 1-10 emitter electrodes, the invention is not limited to any range of emitter electrodes used.
In the descriptions above, various functional modules are given descriptive names, such as “ion wind fan power supply.” The functionality of these modules can be implemented in software, firmware, hardware, or a combination of the above. None of the specific modules or terms—including “power supply” or “ion wind fan”—imply or describe a physical enclosure or separation of the module or component from other system components.
Furthermore, descriptive names such as “emitter electrode,” “collector electrode,” and “isolator,” are merely descriptive and can be implemented in a variety of ways. For example, the “collector electrode,” can be implemented as one piece of metallic structure, but it can also be made of multiple members spaced apart, and connected by wires or other electrical connections to the same voltage potential, such as ground.
Similarly, the isolator can be the substantially frame-like component shown in
This application claims priority to U.S. Provisional Application Ser. No. 61/233,112 filed Aug. 11, 2009, the contents of which are incorporated herein by reference in their entirety.
| Number | Date | Country | |
|---|---|---|---|
| 61233112 | Aug 2009 | US |
