The present invention is related to ion wind fans, and in particular to reducing ozone produced by 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, such as light emitting diodes, chips, and so on. Heat sinks are a common device used to prevent overheating. Heat sinks dissipate heat from a heat source using conduction and convection. To increase the heat dissipation of a heat sink, conventional rotary fans have been used to move air across the surface of the heat sink to increase convection. Conventional fans have many disadvantages when used in consumer electronics products, such as noise, weight, size, and failure of moving parts and bearings. A solid-state fan using ion wind, also known as corona 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.
One potential drawback of ion wind devices is that the high electric field that results in ion generation and ultimately ionic wind, also generates ozone (O3). Ground-level ozone—as opposed to ozone found in the ozone layer of the stratosphere—is a considered a pollutant and can be harmful to the lungs if inhaled in large concentrations. In large concentrations, ozone also has an unpleasant odor.
The problem of ozone production in ion wind fans has been known for some time. For example, U.S. Pat. No. 6,522,536 to Brewer et al., entitled “Electrostatic Cooling of a Computer,” discloses an ion wind device consisting of a high voltage ionization strip that ionizes the air, and a grounded heat sink that attracts the ions creating ionic wind. Brewer et al. describes coating the surface or channels of the heat sink with a catalyst that breaks down ozone.
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 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.
The electronic device will include the heat source (not shown), and a heat sink 12 to dissipate heat from the hear source. Since
As discussed above, the ion wind fan 10 operates by creating a high electric field around one or more emitter electrodes resulting in the generation of ions, which are then attracted to a collector electrode, thereby creating airflow. The airflow thus created can then be used to move air through the channels of a heat sink, such as the heat sink 12 shown in
As explained above, some ion wind fans 10 generate ozone. One way to mitigate ozone production described in U.S. Pat. No. 6,522,536 to Brewer et al., entitled “Electrostatic Cooling of a Computer,” is coating the surface and the channels of the heat sink 12 with a catalyst that breaks down ozone. There are several shortcomings of the catalyst-coated heat sink disclosed by the '536 patent. In the '536 patent, the heat sink itself is used as a collector electrode. However, in many embodiments, it is preferable to not electrically ground the heat sink and provide a heat sink that is separate physically from the ion wind fan, as shown in
As shown in
One embodiment of a heat sink having protruding ozone catalyzing fins is now described with reference to
In one embodiment, the slots 22 are disposed substantially perpendicular to the side of the fin 20, however angles other than 90 degrees may be used. In the embodiment illustrated by
In
A heat sink 30 utilizing the fin 20 having slots 22 and ozone catalyst fins 24 is illustrated in a side-view in
In one embodiment, the width of the ozone catalyst fin 24a is greater than the depth of the slot 22a, causing ozone catalyst fin 24a to protrude from the heat sink 30 and from the heat sink fin 20. In
These ranges are large, as the optimum sizing of both the heat sink 30 and the ozone catalyst fins 24 is dependent on various application-specific factors such as the size and temperature of the heat source, the power of the ion wind fan, the number of emitter electrodes, the airflow and pressure generated by the ion wind fan, the amount of ozone generated by the ion wind fan, and other such design considerations. The embodiments of the present invention are not limited to any particular size or percentage protrusion.
In
A frontal-view of the heat sink 30 is shown in
In contrast, the lower ozone catalyst fin 24b is shown to be flush with the sides of the heat sink 30. In other embodiments, other ozone catalyst fins 24 can be shorter in length than the heat sink 30 in wide. While the embodiments described with reference to
For example, a fin-stack type heat sink 40 having three ozone catalyst fins is shown and described with reference to
One reason it can be advantageous for an ozone catalyst fin to protrude from a heat sink, is that ozone concentrations tend to be highest near the ion wind fan, but positioning a heat sink in the immediate vicinity of an ion wind fan without leaving a gap an result in high airflow restriction.
The heat sink 50 can be similar or even identical to the embodiments described with reference to
The fins 52 extend substantially perpendicular from the base 56 and form channels for airflow. Ozone catalyst fins 54a and 54b are provided horizontally across the heat sink 50, such that the ozone catalyst fins 54 extend substantially perpendicular to both the air flow generated by the ion wind fan 60 and the orientation of the fins 52 and channels. In one embodiment, the ozone catalyst fins 54 are positioned substantially parallel to the base 56.
In one embodiment, the ion wind fan 60 is positioned so that the protruding portions of the ozone catalyst fins 54 are very near the collector 64 of the ion wind fan 60, without actually contacting the collector 64. In one embodiment, the distance between the collector 64 and the ozone catalyst fins 54 is in the range of 0-1 mm, but larger separations can also be used.
In one embodiment, the ozone catalyst fins 54 are positioned so that they are as close as possible to the emitter electrodes 62 of the ion wind fan 60. In some ion wind fans, ozone is generated in the vicinity of the emitter electrodes. In the embodiment shown in
As shown in
This is visually demonstrated in
In other embodiments, there need not be an equal number of emitter electrodes and ozone catalyst fins. For example, the heat sink 50 of
In the descriptions of some of the Figures above, the ozone catalyst fins have been described as being associated an emitter electrode. However, in other embodiments, there need not be a one-to-one association between ozone catalyst fins and emitter electrodes. The invention is not limited to any specific number of ozone catalyst fins or emitter electrodes of the ion wind fan. For example, for an ion wind fan using a pin grid array as emitter electrodes, there are likely to be many more emitter electrodes in the ion wind fan than ozone catalyst fins on the heat sink.
Furthermore, in
In the descriptions above, the ion wind fan has not been described in much detail, as embodiments of the present invention can be used with any ion wind device. Furthermore, the ozone catalyst fins described above can be attached or otherwise part of any type of heat sink. The present invention is not limited to vertical-fin-on-base type heat sinks that are used above for purposes of illustration.
In the descriptions above, the ozone catalyst fins are described as being inserted into slots on heat sink fins to attach the ozone catalyst fins to heat sinks. However, any other means of attachment can be used. Furthermore, the ozone catalyst fins do not need to be separately attached to the heat sink. In some embodiments, the heat sink can be integrally formed with ozone catalyst fins, for example during the molding, pressing, snapping, or other forming process. Furthermore, the heat sink may not be a fin-type heat sink. Embodiments of the present invention can be implemented, for example, in a pin-type heat sink as well.
In the description above, and in the claims below, the term “substantially” generally mean within a minor variation, based on context. For example, the heat sink fins projecting substantially perpendicular from the base of the heat sink means that the fins can project at angles 80-100 degrees for example, but not 45 degrees.
In the descriptions above, various functional modules are given descriptive names, such as “ozone catalyst fin,” “ion wind fan,” and “heat sink fin.” These terms are descriptive. For example, fins do not necessarily have to be fin shaped; many shapes can be used.
The present application claims the priority benefit of U.S. Provisional Patent Application No. 61/233,112, entitled “MITIGATING OZONE IN A DEVICE HAVING AN EHD SOLID STATE FAN”, filed Aug. 11, 2009, which is hereby incorporated by reference in its entirety.
Number | Date | Country | |
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61233112 | Aug 2009 | US |