The embodiments of the present invention are related to a solid-state lighting device, and in particular to a solid-state lighting device containing an ion wind fan.
It is well known that heat and the thermal management of heat is an issue for power light-emitting diodes (LEDs) used for illumination. Current LED light bulbs generally use a passive heat sink for thermal management. The body of the LED bulb is generally a metallic heat sink with fins to increase surface area for convection.
Heat sinks use conduction and convection to dissipate heat and thermally manage a 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 would have many disadvantages when used in an LED light device, such as noise, weight, size, efficiency, and reliability caused by the failure of moving parts and bearings.
A solid-state fan using ionic wind to move air addresses many of the disadvantages of conventional fans. However, integrating an ion wind fan into a solid-state lighting device present numerous challenges.
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
As described partially above, ion wind is generated by the ion wind fan 10 by applying a high voltage potential across the emitter 12 and collector 14 electrodes. This creates a strong electric field around the emitter electrodes 12, strong enough to ionize the air in the vicinity of the emitter electrodes 12, in effect creating a plasma region. The ions are attracted to collector electrode 12, and as they move in air gap along the electric field lines, the ions bump into neutral air molecules, creating airflow. On a real world collector electrode 14, air passage openings (not shown) allow the airflow to pass through the collector 14 thus creating an ion wind fan.
An example of such 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 the embodiment shown, the light bulb 40 includes a screw-type base 41 to mate with a standard light socket to receive electricity from the mains power. In other embodiments various other electrical connectors and sockets could be used. The light bulb 40 includes a bulb housing, broken out into the electronics housing 42 and the fan housing 43 in
The fan housing 43 includes a set of intake openings 46 and a set of exhaust openings that allow air to flow through the fan housing 43. The electronics housing 42 has a hollow cavity to house various electronics components, such as an LED power supply and driver, and the ion wind fan power supply. In one embodiment, this hollow cavity is then electrically from the fan housing 43.
In one embodiment, an ion wind fan 30 resides inside the fan housing 43, as shown in
The heat spreader 52 portion of the heat sink 50 acts as the top surface of the fan housing 43, so that the upstream fins 54 and downstream fins 53 of the heat sink 50 reside in the fan housing 43, so that the airflow generated by the ion wind fan 30 impinges on the heat sink fins. The heat sink 50 can be manufactured as a single cast piece of metal, but other manufacturing techniques can also be used. In yet other embodiments, the heat spreader 52 and the fins 53-4 can be assembled from separate subcomponents (e.g. by welding on each fin).
In one embodiment, the LED module 58 providing illumination is mounted on the heat spreader 52. In
Various commercially available LED modules 58 can be used, such as an ES-, RS-, or LS-Series LED Array available from BridgeLux Incorporated. However, any other LED engine, module, or array from any manufacturer can be used, in addition to other solid-state light engines currently available or not yet in existence. The bulb 40 also includes a cover/lens 58. The cover 58 is transparent or translucent, and may act as a lens or other optics.
One embodiment of the present invention is now described with reference to
The power conditioning electronics 72 can include various protection circuitry as well as a transformer or converter to alter the current to a format suited for the LED power supply 76 and an ion wind fan power supply 74. In one embodiment, the power conditioning circuit 72 includes a switched-mode power supply where the primary winding of the output transformer is part of the power conditioning 72 electronics and the IWF power supply 74 and the LED power supply 76 each have a secondary winding to the output transformer. However, the drive electronics 71 can be implemented is a variety of ways, and the specific implementations are not relevant to the various embodiments of the present invention.
Also shown in
In one embodiment, the LED module 89 uses direct current (DC) to power its LEDs. For example, a BridgeLux Part Number BXRA-C2002 ES-Serieas LED Array operates at around 16 volts (V) DC. Most currently available LED modules operate in the range of 7-30V DC. The LED power supply 76 is designed to provide current at the voltage required by the LED module 89.
The LED power supply 76 has a positive (high) terminal and a negative (low) terminal, denoted by a + and a − respectively. The voltage potential between the high voltage terminal 76(+) and the low voltage terminal 76(−) is the voltage at with the current is provided to the LED module 89. The LED module 89 also has a high voltage terminal 89(+) and a low voltage terminal 89(−). As is understood by those skilled in the art, the LED module 89 is powered by the LED power supply 76 by electrically coupling the high voltage terminals together—76(+) and 89(+)—and the respective low voltage terminals together—76(−) and 89(−)—as shown in
Similarly, in one embodiment, the emitter electrodes 81 of the ion wind fan 80 are connected to the high voltage terminal 74(+) of the ion wind fan power supply 74 and the collector electrode 82 is connected to the low voltage terminal 74(−). In other embodiments, the ion wind fan 80 may use negative corona or AC coronal implementations. In one embodiment, the voltage generated by the ion wind power supply is thousands of volts, and thus much exceeds the voltages produced by a typical LED power supply 76.
In one embodiment, the heat sink 86 and the heat sink fins 87 are made of electrically conductive material, such as metals like aluminum or copper. As explained above, the ion wind fan 80 operates by creating an electrostatic field and moving charged particles (ions). Since the ion wind fan 80 is physically positioned to provide forced convection for the heat sink 86, it is generally in relatively close proximity to the heat sink 89. In
Because of this proximity, the heat sink can become charged or conduct some current due to being in the electrostatic field or by impacts from moving charged particles. If the differential voltage across the heat sink 86 and the LED module 89 exceeds a certain threshold, arcing or other undesirable current flow can occur between the heat sink 86 and the LED module 89. In one embodiment, these issued caused by having an ion wind fan 80 in close proximity to a metallic heat sink 86 used to thermally manage an LED module 89 are addressed by electrically coupling the heat sink 86 to the low voltage terminal of the LED power supply 76(−), as shown in
Usually, a light socket is not grounded, and has only two electrical connections. Thus, the absolute potential of the low voltage terminal 76(−) is not always known, and is implementation specific. It usually will not be at the same potential as the “neutral” wire coming into the light socket, but in some cases it may be. However, the electric potential of the heat sink 86 is controlled by connecting it to the low voltage terminal 76(−) of the LED power supply 76, and thus not allowing it to float to whatever potential its environment would allow. In such an embodiment, the heat sink 86 cannot be grounded, but should be voltage controlled to be at the same potential as the LED module 89.
In one embodiment, the MCPCB is mounted on the heat sink 86 using a thermal interface material (TIM) 98 that acts both as an adhesive and as an efficient conductor of heat. In other embodiments, the MCPCB 86 can be directly coupled to the heat sink 86. In yet other embodiments in which no MCPCB is used, the LED package 94 can be directly mounted on the heat sink 86, or use a plurality of heat slugs in thermal contact with the heat sink 86.
In the embodiment shown, the heat sink 86 has two sets of fins 87, one upstream 87a and one downstream 87b of the ion wind fan 80, much like as shown in
In the descriptions above, various functional modules are given descriptive names, such as “ion wind fan power supply,” and “LED 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. Also, terms such as “lamp,” “light device,” “light bulb,” and the like are used interchangeably in this application, without limitation to any specific shape.
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 (as shown in the
Similarly, the isolator can be the substantially frame-like component shown in
Furthermore, various directional and orientational terms such as “front” and “back” and “rear,” “left” and “right,” “top” and “bottom,” and the like are used herein only for convenience. No fixed or absolute directional or orientational limitations are intended by the use of these words. For example, an LED light bulb may be installed facing down or facing up. Alternatively, various components may be oriented differently inside of the LED bulb without altering the fundamental nature of the scope and spirit of this invention.