Synthetic Jet Actuators and Ejectors and Methods For Using The Same

Abstract

A thermal management system is provided which comprises (a) a synthetic jet actuator; and (b) a frame having at least one element therein which pressingly engages said synthetic jet actuator.

Description

FIELD OF THE DISCLOSURE

The present disclosure relates generally to synthetic jet ejectors, and more particularly to systems and methods for attaching heat sinks to synthetic jet ejectors.

BACKGROUND OF THE DISCLOSURE

A variety of thermal management devices are known to the art, including conventional fan based systems, piezoelectric systems, and synthetic jet ejectors. The latter type of system has emerged as a highly efficient and versatile solution, especially in applications where thermal management is required at the local level.

Various examples of synthetic jet ejectors are known to the art. Earlier examples are described in U.S. Pat. No. 5,758,823 (Glezer et al.), entitled “Synthetic Jet Actuator and Applications Thereof”; U.S. Pat. No. 5,894,990 (Glezer et al.), entitled “Synthetic Jet Actuator and Applications Thereof”; U.S. Pat. No. 5,988,522 (Glezer et al.), entitled Synthetic Jet Actuators for Modifying the Direction of Fluid Flows”; U.S. Pat. No. 6,056,204 (Glezer et al.), entitled “Synthetic Jet Actuators for Mixing Applications”; U.S. Pat. No. 6,123,145 (Glezer et al.), entitled “Synthetic Jet Actuators for Cooling Heated Bodies and Environments”; and U.S. 6,588,497 (Glezer et al.), entitled “System and Method for Thermal Management by Synthetic Jet Ejector Channel Cooling Techniques.

Further advances have been made in the art of synthetic jet ejectors, both with respect to synthetic jet ejector technology in general and with respect to the applications of this technology. Some examples of these advances are described in U.S. Pat. No. 7,252,140 (Glezer et al.), entitled “Apparatus and Method for Enhanced Heat Transfer”; U.S. 7,606,029 (Mahalingam et al.), entitled “Thermal Management System for Distributed Heat Sources”; U.S. Pat. No. 7,607,470 (Glezer et al.), entitled “Synthetic Jet Heat Pipe Thermal Management System”; U.S. Pat. No. 7,760,499 (Darbin et al.), entitled “Thermal Management System for Card Cages”; U.S. Pat. No. 7,768,779 (Heffington et al.), entitled “Synthetic Jet Ejector with Viewing Window and Temporal Aliasing”; U.S. Pat. No. 7,784,972 (Heffington et al.), entitled “Thermal Management System for LED Array”; U.S. Pat. No. 7,819,556 (Heffington et al.), entitled “Thermal Management System for LED Array”; U.S. Pat. No. 7,932,535 (Mahalingam et al.), entitled “Synthetic Jet Cooling System for LED Module”; U.S. Pat. No. 8,030,886 (Mahalingam et al.), entitled “Thermal Management of Batteries Using Synthetic Jets”; U.S. Pat. No. 8,035,966 (Reichenbach et al.), entitled “Electronics Package for Synthetic Jet Ejectors”; U.S. Pat. No. 8,006,410 (Booth et al.), entitled “Light Fixture with Multiple LEDs and Synthetic Jet Thermal Management System”; U.S. Pat. No. 8,069,910 (Beltran et al.), entitled “Acoustic Resonator for Synthetic Jet Generation for Thermal Management”; and U.S. Pat. No. 8,136,576 (Grimm), entitled “Vibration Isolation System for Synthetic Jet Devices”.

In addition to the foregoing, other advances have been made in the art of synthetic jet ejectors, both with respect to synthetic jet ejector technology in general and with respect to the applications of this technology. Some examples of these advances are described in U.S. 20100263838 (Mahalingam et al.), entitled “Synthetic Jet Ejector for Augmentation of Pumped Liquid Loop Cooling and Enhancement of Pool and Flow Boiling”; U.S. 20100039012 (Grimm), entitled “Advanced Synjet Cooler Design For LED Light Modules”; U.S. 20100033071 (Heffington et al.), entitled “Thermal Management of LED Illumination Devices”; U.S. 20090141065 (Darbin et al.), entitled “Method and Apparatus for Controlling Diaphragm Displacement in Synthetic Jet Actuators”; U.S. 20090109625 (Booth et al.), entitled Light Fixture with Multiple LEDs and Synthetic Jet Thermal Management System“; U.S. 20090084866 (Grimm et al.), entitled Vibration Balanced Synthetic Jet Ejector”; U.S. 20080219007 (Heffington et al.), entitled “Thermal Management System for LED Array”; U.S. 20080151541 (Heffington et al.), entitled “Thermal Management System for LED Array”; U.S. 20080043061 (Glezer et al.), entitled “Methods for Reducing the Non-Linear Behavior of Actuators Used for Synthetic Jets”; U.S. 20080009187 (Grimm et al.), entitled “Moldable Housing design for Synthetic Jet Ejector”; U.S. 20070096118 (Mahalingam et al.), entitled “Synthetic Jet Cooling System for LED Module”; U.S. 20070023169 (Mahalingam et al.), entitled “Synthetic Jet Ejector for Augmentation of Pumped Liquid Loop Cooling and Enhancement of Pool and Flow Boiling”; U.S. 20070119573 (Mahalingam et al.), entitled “Synthetic Jet Ejector for the Thermal Management of PCI Cards”; U.S. 20070119575 (Glezer et al.), entitled “Synthetic Jet Heat Pipe Thermal Management System”; U.S. 20070127210 (Mahalingam et al.), entitled “Thermal Management System for Distributed Heat Sources”; and U.S. 20070141453 (Mahalingam et al.), entitled “Thermal Management of Batteries using Synthetic Jets”.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an illustration depicting the manner in which a synthetic jet actuator operates.

FIG. 2 is an illustration of a typical two-sided coil-type linear motor of the general type frequently used in actuators for synthetic jet ejectors.

FIGS. 3-6 are illustrations of a press attachment system for a synthetic jet ejector.

FIG. 7 is an illustration of an actuator equipped with threading to rotatingly engage a housing.

FIG. 8 is an illustration of a typical two-sided coil-type linear motor of the general type frequently used in actuators for synthetic jet ejectors.

FIG. 9 is an illustration of a heat sink with a back iron for a synthetic jet ejector attached thereto.

FIG. 10 is an illustration of a heat sink with a housing component molded onto a surface thereof

FIG. 11 is an illustration of a heat sink with a housing component molded onto a surface thereof

FIG. 12 is an illustration of a prior art LED mounted on a heat sink with an intervening conductive carrier.

FIG. 13 is an illustration of an LED mounted on a heat sink without an intervening conductive carrier.

FIG. 14 is an illustration of a typical two-sided coil-type linear motor of the general type frequently used in actuators for synthetic jet ejectors.

FIG. 15 is a perspective view of a first embodiment of a diaphragm made in accordance with the teachings herein.

FIG. 16 is a perspective view of, partially in section, of the diaphragm of FIG. 15.

FIG. 17 is a perspective view illustrating the interface between the diaphragm of FIG. 15 and the bobbin and retaining ring of the synthetic jet actuator.

FIG. 18 is a perspective view of a second embodiment of a diaphragm made in accordance with the teachings herein.

FIG. 19 is a perspective view of, partially in section, of the diaphragm of FIG. 18.

FIG. 20 is a perspective view illustrating the interface between the diaphragm of FIG. 18 and the heat sink and housing of the synthetic jet actuator.

FIG. 21 is an illustration of a means for attaching a diaphragm of a synthetic jet actuator directly to the walls of a heat sink.

FIGS. 22-25 illustrate a 2-phase moving motor coil configuration for a synthetic jet actuator.

FIGS. 26-36 illustrate a synthetic jet ejector design in accordance with the teachings herein which implements a 2-Piece actuator assembly into a synthetic jet thermal management system.

FIG. 37 illustrates a single motor dual piston differential pulsed air actuator in accordance with the teachings herein.

FIGS. 38-41 illustrate a dual actuator synthetic jet ejector with a unified magnetic field.

FIGS. 42-43 illustrate a diaphragm with a bellows shape formed in it, and having an oblong coil wrapped around the perimeter of the bellows.

FIG. 44 depicts a low profile thermal management system which uses synthetic jets and a spider-like suspension movement.

FIG. 45 illustrates an integrated flat coil and flat piston which may be utilized to reduce the axial height of an actuator used in a synthetic jet thermal management system.

FIGS. 46-47 depict a modular synthetic jet engine.

FIGS. 48-50 depict a multi-point spring suspension for synthetic jet actuators.

FIG. 51 illustrates a perpendicular synthetic jet engine.

FIGS. 52-69 depict a one piece bobbin/diaphragm flange made in accordance with the teachings herein.

FIGS. 70-72 depict a single magnetic synthetic actuator design in accordance with the teachings herein.

FIG. 73 is an illustration of a moving coil synthetic jet actuator which includes an inkjet printed interconnect.

FIG. 74 is an illustration of a synthetic jet actuator which utilizes a method for routing tinsel leads to avoid contact with the surround.

FIG. 75 is an illustration of a synthetic jet actuator which utilizes a method for routing tinsel leads to avoid contact with the surround.

FIG. 76 is a side view, partially in section, which illustrates a voice coil equipped with through-motor voice coil leads.

FIG. 77 is a top view of the voice coil of FIG. 76.

FIG. 78 is a top view of a synthetic jet actuator which utilizes tinsel routing scheme that avoids contact with the surround.

FIG. 79 is a top view of a synthetic jet actuator having a conventional tinsel deployment.

FIG. 80 is a cross-sectional view of the synthetic jet actuator of FIG. 79.

FIG. 81 is a top view of a synthetic jet actuator having a tinsel deployment in accordance with the teachings herein.

FIG. 82 is a cross-sectional view of the synthetic jet actuator of FIG. 81.

FIG. 83 is a cross-sectional view showing a tinsel-free synthetic jet actuator in accordance with the teachings herein.

FIG. 84 is a top view of the synthetic jet actuator of FIG. 83.

FIGS. 85-87 are illustrations of tinsel-free synthetic jet actuators in accordance with the teachings herein which have patterned metal diaphragm interconnects.

FIG. 88 is a top view of an synthetic jet actuator in accordance with the teachings herein which utilizes a spiral tinsel routing design.

FIG. 89 is a perspective view of an apparatus for using fiber optic reflectance sensors to measure displacements in the diaphragm of a synthetic jet actuator.

FIG. 90 depicts an integrated circuit (ASIC) that may be used to drive an LED array.

FIG. 91 depicts an LED lamp that is powered by 110/220VAC Mains power and is cooled by a synthetic jet ejector which is also powered by 110/220 V AC Mains power.

FIGS. 92-96 illustrate a method which uses the changing capacitance between moving conductive plates to determine the relative position of the moving diaphragm (one of the plates) to a fixed plate such as a housing cover or base plate.

FIGS. 97-99 are diagrams illustrating diaphragm motion/ displacement/capacitance measurements.

FIGS. 100-101 depict a synthetic jet actuator control with integrated IR sensing of target temperature.

FIG. 102 is a graph of power (W) as a function of frequency (Hz).

FIG. 103 is a graph of phase (degree) as a function of frequency (Hz).

FIG. 104 is an illustration of a means for optically measuring dynamic actuator diaphragm position.

SUMMARY OF THE DISCLOSURE

In one aspect, a method is provided for assembling a thermal management system. The method comprises (a) providing a synthetic jet actuator; (b) providing a PCB having a frame attached thereto which is equipped with at least one element therein which pressingly engages the synthetic jet actuator; and (c) attaching the synthetic jet actuator to said frame by way of the element.

In another aspect, a thermal management system is provided which comprises (a) a synthetic jet actuator; and (b) a frame having at least one element therein which pressingly engages said synthetic jet actuator.

In a further aspect, a thermal management system is provided which comprises (a) a synthetic jet actuator equipped with a first mating feature; and (b) a housing equipped with a second mating feature; wherein the first mating feature rotatingly engages the second mating feature, and wherein at least one of the first and second mating features is a threaded surface.

In another aspect, a thermal management system is provided which comprises a heat sink, and a synthetic jet actuator comprising a stator and a voice coil; wherein said stator includes a back iron that is either attached to, or is integral with, said heat sink.

In another aspect, a method is provided for making a thermal management device equipped with a synthetic jet ejector, a heat sink and a housing. The method comprises placing the heat sink into a mold; and using the mold to form a portion of the housing.

In a further aspect, a light source is provided which comprises a heat sink; and an LED mounted on said heat sink such that a surface of the LED is in physical contact with a surface of the heat sink.

In still another aspect, a synthetic jet actuator is provided which comprises a diaphragm having an inner perimeter and an outer perimeter; and a clamp which physically secures at least a portion of at least one of the inner and outer perimeters into place.

In another aspect, a synthetic jet actuator is provided which comprises a diaphragm having an inner and outer perimeter; a first protrusion disposed on at least one of said inner and outer perimeters; and a first member which engages said first protrusion, thereby securing at least a portion of at least one of the inner and outer perimeters into place.

In a further aspect, a synthetic jet actuator is provided which comprises a diaphragm having an inner and outer perimeter; a first protrusion disposed on at least one of said inner and outer perimeters; and engaging means for engaging said first protrusion, thereby securing said diaphragm in place.

In a further aspect, a synthetic jet actuator is provided which comprises a diaphragm; and a frame which supports said diaphragm; wherein said frame is equipped with a first threaded surface.

In yet another aspect, a synthetic jet actuator is provided which comprises (a) a diaphragm; (b) a coil former; and first and second motor coils spaced apart and disposed along the axis of the coil former such that, when the diaphragm is in a first position, the first coil is disposed in the center of the magnetic inductance field, and when the diaphragm is in a second position, the second coil is disposed in the center of the magnetic inductance field.

In another aspect, a method is provided for forming tinsel on a synthetic jet actuator. The method comprises (a) providing a synthetic jet actuator assembly comprising a coil, driver electronics, and a surround; and (b) completing an electrical circuit between the coil and the driver electronics by depositing a conductive ink across the surround.

In another aspect, a synthetic jet actuator is provided which comprises (a) a coil, driver electronics, and a surround; and (b) a conductive ink which extends across the surround and which forms an electrical circuit between the coil and the driver electronics.

In a further aspect, a synthetic jet actuator is provided which comprises (a) a diaphragm equipped with a surround; (b) a voice coil having first and second terminal portions; (c) a pot structure having first and second portions which are electrically isolated from each other; (d) a first portion of tinsel having a first end which is in electrical communication with said first terminal portion of said voice coil, and a second end which is in electrical communication with said first portion of said pot structure; and (e) a second portion of tinsel having a first end which is in electrical communication with said second terminal portion of said voice coil, and a second end which is in electrical communication with said second portion of said pot structure.

In still another aspect, a synthetic jet actuator is provided which comprises (a) a diaphragm equipped with a surround; (b) a voice coil having first and second terminal portions; (c) a pot structure having first and second passageways defined therein; (d) a first portion of tinsel which extends through said first passage way and which is in electrical communication with said first terminal portion of said voice coil; and (e) a second portion of tinsel which extends through said second passage way and which is in electrical communication with said second terminal portion of said voice coil.

In another aspect, a synthetic jet actuator is provided which comprises (a) a diaphragm equipped with a surround; (b) a voice coil having first and second terminal portions; (c) a pot structure having first and second passageways defined therein; (d) a first conductive element which extends through said first passage way and which is in electrical communication with said first terminal portion of said voice coil; and (e) a second portion of tinsel which extends through said second passage way and which is in electrical communication with said second terminal portion of said voice coil.

In a further aspect, a synthetic jet actuator is provided which comprises (a) a diaphragm equipped with a surround; and (b) a plurality of electrically conductive elements integrated with said surround.

In still another aspect, a method is provided for calibrating a synthetic jet actuator is provided. The method comprises (a) providing a synthetic jet actuator which is equipped with a diaphragm and disposed within a housing, wherein the housing has an aperture therein; (b) providing a measuring device which measures the displacement of a diaphragm in a synthetic jet actuator, the device including a first portion which releasably engages the aperture and a second portion which includes an optic reflectance sensor and which extends through the aperture so that, when the first portion releasably engages the aperture, the reflectance sensor is properly positioned with respect to the diaphragm to sense reflections from the diaphragm; (c) releasably engaging the aperture with the first portion; (d) measuring the displacement of the diaphragm with the measuring device; and (e) using the measured displacement to calibrate the synthetic jet actuator.

DETAILED DESCRIPTION

The devices and methodologies disclosed herein utilize synthetic jet actuators or synthetic jet ejectors. Prior to describing these devices and methodologies, a brief explanation of a typical synthetic jet ejector, and the manner in which it operates to create a synthetic jet, may be useful.

The formation of a synthetic jet may be appreciated with respect to FIGS. 1-3. FIG. 1 depicts a synthetic jet ejector 101 comprising a housing 103 which defines and encloses an internal chamber 105. The housing 103 and chamber 105 may take virtually any geometric configuration, but for purposes of discussion and understanding, the housing 103 is shown in cross-section in FIG. 1 to have a rigid side wall 107, a rigid front wall 109, and a rear diaphragm 111 that is flexible to an extent to permit movement of the diaphragm 111 inwardly and outwardly relative to the chamber 105. The front wall 109 has an orifice 113 therein (see FIG. 1) which may be of various geometric shapes. The orifice 113 diametrically opposes the rear diaphragm 111 and fluidically connects the internal chamber 105 to an external environment having ambient fluid 115.

The movement of the flexible diaphragm 111 may be controlled by any suitable control system 117. For example, the diaphragm may be moved by a voice coil actuator. The diaphragm 111 may also be equipped with a metal layer, and a metal electrode may be disposed adjacent to, but spaced from, the metal layer so that the diaphragm 111 can be moved via an electrical bias imposed between the electrode and the metal layer. Moreover, the generation of the electrical bias can be controlled by any suitable device, for example but not limited to, a computer, logic processor, or signal generator. The control system 117 can cause the diaphragm 111 to move periodically or to modulate in time-harmonic motion, thus forcing fluid in and out of the orifice 113.

Alternatively, a piezoelectric actuator could be attached to the diaphragm 111. The control system would, in that case, cause the piezoelectric actuator to vibrate and thereby move the diaphragm 111 in time-harmonic motion. The method of causing the diaphragm 111 to modulate is not particularly limited to any particular means or structure.

The operation of the synthetic jet ejector 101 will now be described with reference to FIGS. 2-3. FIG. 2 depicts the synthetic jet ejector 101 as the diaphragm 111 is controlled to move inward into the chamber 105, as depicted by arrow 125. The chamber 105 has its volume decreased and fluid is ejected through the orifice 113. As the fluid exits the chamber 105 through the orifice 113, the flow separates at the (preferably sharp) edges of the orifice 113 and creates vortex sheets 121. These vortex sheets 121 roll into vortices 123 and begin to move away from the edges of the orifice 109 in the direction indicated by arrow 119.

FIG. 3 depicts the synthetic jet ejector 101 as the diaphragm 111 is controlled to move outward with respect to the chamber 105, as depicted by arrow 127. The chamber 105 has its volume increased and ambient fluid 115 rushes into the chamber 105 as depicted by the set of arrows 129. The diaphragm 111 is controlled by the control system 117 so that, when the diaphragm 111 moves away from the chamber 105, the vortices 123 are already removed from the edges of the orifice 113 and thus are not affected by the ambient fluid 115 being drawn into the chamber 105. Meanwhile, a jet of ambient fluid 115 is synthesized by the vortices 123, thus creating strong entrainment of ambient fluid drawn from large distances away from the orifice 109.

Many of the synthetic jet actuators developed thus far utilize a voice coil, and hence are movable coil type linear motors. Such motors move directly on a straight line, and thus have high operational speeds and allow precise control over positioning.

In movable coil type linear motors, a movable unit performs linear motion due to thrust generated between a coil unit and one or more permanent magnets. According to the number and position of the permanent magnets, the movable coil type linear motor is classified as a one-sided linear motor or a two-sided linear motor. That is, the movable coil type linear motor is classified into the one-sided linear motor and two-sided linear motor according to whether the permanent magnets which are stators are installed at one side or both sides of the coil unit.

Referring to FIG. 2, the two-sided type linear motor includes a stator 1 and a movable unit 2. The stator 1 is composed of a ‘U’ shaped stator back iron 3, and a plurality of permanent magnets 4 sequentially aligned on the facing surfaces of the stator back iron 3 in which N and S polarities are alternately generated. The movable unit 2 includes a movable unit back iron 5 positioned at an upper opening unit side of the stator back iron 3, and a coil unit 6 installed between the permanent magnets 4 at the lower portion of the movable unit back iron 5 with a constant gap (C). In a state where the stator 1 and the movable unit 2 are separated by the gap (C), as a predetermined distance, when current is applied to the coil unit 6, thrust is generated between the permanent magnets 4 due to the Fleming's left-hand law, and thus the movable unit 2 performs the direct linear motion due to the thrust.

When a control device (not shown) applies current to the coil unit 6, the current is transferred to a coil of the coil unit 6, and magnetic field and thrust are generated between the permanent magnets 4 and the coil unit 6 installed inside the stator back iron 3, thereby moving the movable unit 2 in the front/rear direction. Here, the control device (not shown) controls a movement speed of the movable unit 2 and thrust by the movement according to a winding number of the coil and the supply current.

While synthetic jet ejectors have many advantages, at present, their wide scale commercial use is hindered by the cost of manufacturing these devices, and in particular, by the parts and tooling requirements necessitated by existing synthetic jet ejector designs. Moreover, given the continually shrinking sizes of the devices that serve as hosts to synthetic jet ejectors (and the thermal management systems incorporating them), there is a need in the art for a means by which the dimensions of synthetic jet actuators and synthetic jet ejectors can be reduced. In addition, further improvements are desirable with respect to the expected lifetimes of these devices.

At least some of the foregoing issues are attributable to the bond requirements between the inner perimeter of the diaphragm and the other components of the actuator (e.g., the bobbin), and/or the bond requirements between the outer perimeter of the diaphragm and the other components of the actuator (e.g., the heat sink and/or housing). Frequently, the bond between these components is a silicone-plastic or silicone-metal bond. In addition to the dissimilarity between the materials of these components, the bond interfaces at these locations are subject to considerable stress and represent a common point of failure. This is especially so since the diaphragm is one of the few moving components of these devices.

It has been found that the ease of assembly for a device incorporating a synthetic jet ejector or synthetic jet actuator may be enhanced, and the cost of such a device may be reduced, by providing such a device with a means for readily incorporating it into a host device. This may be achieved, for example, by providing a synthetic jet actuator which may be attached to a substrate, such as, for example, a PCI board, through a press-on attachment. Such a design avoids the need for a gluing process, which is the typical means currently used to incorporate a synthetic jet ejector or synthetic jet actuator into a host device. A similar end may be achieved by providing a synthetic jet actuator equipped with a first mating element, and a housing equipped with a second mating element, wherein the first and second mating elements rotatingly engage each other, and wherein at least one of the first and second mating elements is a threaded surface.

FIGS. 3-6 depict an embodiment of a device in accordance with the teachings herein. Currently, a low profile synthetic jet ejector is mounted onto a PCI heat sink using cantilevered spring bars and a rubber isolator. This allows the synthetic jet ejector to move independently of the heat sink, but requires that the synthetic jet ejector has adequate clearance for movement. In applications where there is not enough space for such a mounting system, the synthetic jet ejector may be mounted rigidly to the heat sink and PCI card.

One way to do this is with a press on attachment system. First, the synthetic jet ejector is attached to the board with pins which help position it relative to the sink. Then an adhesive is applied to prevent further motion.

The synthetic jet ejector housing has two bosses with cylindrical holes under the front nozzles, one of which has a chamfer under the hole (FIGS. 3-4). The heat sink will have two cantilevered bars attached, which extend vertically, each with a pin on the end which fits into the bosses on the synthetic jet ejector housing (FIG. 5). One pin is chamfered to facilitate assembly. The cantilevered bars are made from stamped steel, with stiffness low enough to permit elastic bending. First, the hinge boss in the housing will be slid over the un-chamfered pin. Next, the flexible support is bent so that the second pin is clear of the housing, allowing the housing to be lowered between the pins. Once the housing is lowered, and the flexible support is released, inserting the pin into the corresponding boss (FIG. 6). The bottom of the actuator housing is then attached to the board with adhesive.

FIG. 7 illustrates another approach to the foregoing problem. As noted above, currently, synthetic jet actuators are glued into their housings. These glues add cost, time, and reliability risk to the product. It has now been found that this problem may be overcome by adding some threads to the actuators outer surfaces that allow for easy screwing in and sealing of the actuator into the housing. Features may also be added to grip the actuator and make it easy to install.

Many of the synthetic jet actuators developed thus far utilize a voice coil, and hence are movable coil type linear motors. Such motors move directly on a straight line, and thus have high operational speeds and allow precise control over positioning.

In movable coil type linear motors, a movable unit performs linear motion due to thrust generated between a coil unit and one or more permanent magnets. According to the number and position of the permanent magnets, the movable coil type linear motor is classified as a one-sided linear motor or a two-sided linear motor. That is, the movable coil type linear motor is classified into the one-sided linear motor and two-sided linear motor according to whether the permanent magnets which are stators are installed at one side or both sides of the coil unit.

Referring to FIG. 8, the two-sided type linear motor includes a stator 1 and a movable unit 2. The stator 1 is composed of a ‘U’ shaped stator back iron 3, and a plurality of permanent magnets 4 sequentially aligned on the facing surfaces of the stator back iron 3 in which N and S polarities are alternately generated. The movable unit 2 includes a movable unit back iron 5 positioned at an upper opening unit side of the stator back iron 3, and a coil unit 6 installed between the permanent magnets 4 at the lower portion of the movable unit back iron 5 with a constant gap (C). In a state where the stator 1 and the movable unit 2 are separated by the gap (C), as a predetermined distance, when current is applied to the coil unit 6, thrust is generated between the permanent magnets 4 due to the Fleming's left-hand law, and thus the movable unit 2 performs the direct linear motion due to the thrust.

When a control device (not shown) applies current to the coil unit 6, the current is transferred to a coil of the coil unit 6, and magnetic field and thrust are generated between the permanent magnets 4 and the coil unit 6 installed inside the stator back iron 3, thereby moving the movable unit 2 in the front/rear direction. Here, the control device (not shown) controls a movement speed of the movable unit 2 and thrust by the movement according to a winding number of the coil and the supply current.

While synthetic jet ejectors have many advantages, at present, their wide scale commercial use is hindered by the cost of manufacturing these devices, and in particular, by the parts and tooling requirements necessitated by existing synthetic jet ejector designs. Moreover, given the continually shrinking sizes of the devices that serve as hosts to synthetic jet ejectors (and the thermal management systems incorporating them), there is a need in the art for a means by which the dimensions of synthetic jet actuators and synthetic jet ejectors can be reduced. In addition, further improvements are desirable with respect to the expected lifetimes of these devices.

It has been found that some of the foregoing infirmities may be addressed by designing the synthetic jet actuator such that the back iron of the synthetic jet actuator is attached to, or incorporated into, the heat sink of a thermal management device incorporating a synthetic jet ejector. Such a configuration allows for the size of the host device to be minimized.

It has further been found that some of the foregoing infirmities may be addressed by replacing the threaded standoff typically used to join a heat sink and a portion of the housing (such as the housing lid) with a housing portion that is molded in situ onto a surface of the heat sink. As a result, these elements are joined during the molding process, thus eliminating the need for the threaded standoff commonly used, or for other fasteners or screws used to affix the housing portion to the heat sink. This approach also avoids the extra assembly steps inherent in the use of such fasteners, screws or threaded standoffs.

It has also been found that some of the foregoing infirmities may be addressed by eliminating unnecessary components of thermally managed devices. For example, in an LED light source equipped with a heat sink (which may be cooled by a synthetic jet ejector), the conductive carrier disposed between the LED and the heat sink may be eliminated. Since each thermal interface adds resistance to the heat removal path, the resulting device may offer less resistance to heat flow and may improve thermal spreading. Moreover, since the light output, reliability and spectral quality of LEDs and lasers are influenced by the temperature of the LED and are typically adversely affected when the device is heated to higher temperatures, this approach may improve these characteristics.

It has further been found that the ease of assembly for a device incorporating a synthetic jet ejector or synthetic jet actuator may be enhanced, and the cost of such a device may be reduced, by providing such a device with a means for readily incorporating it into a host device. This may be achieved, for example, by providing a surface of the synthetic jet ejector or synthetic jet actuator with a threaded surface which can rotatingly engage a suitable (and preferably complimentary) surface in the host device. Such a design also avoids the need for a gluing process, which is the typical means currently used to incorporate a synthetic jet ejector or synthetic jet actuator into a host device.

Many of the synthetic jet actuators developed thus far utilize a voice coil, and hence are movable coil type linear motors. Such motors move directly on a straight line, and thus have high operational speeds and allow precise control over positioning.

In movable coil type linear motors, a movable unit performs linear motion due to thrust generated between a coil unit and one or more permanent magnets. According to the number and position of the permanent magnets, the movable coil type linear motor is classified as a one-sided linear motor or a two-sided linear motor. That is, the movable coil type linear motor is classified into the one-sided linear motor and two-sided linear motor according to whether the permanent magnets which are stators are installed at one side or both sides of the coil unit.

Referring to FIG. 14, the two-sided type linear motor includes a stator 1 and a movable unit 2. The stator 1 is composed of a ‘U’ shaped stator back iron 3, and a plurality of permanent magnets 4 sequentially aligned on the facing surfaces of the stator back iron 3 in which N and S polarities are alternately generated. The movable unit 2 includes a movable unit back iron 5 positioned at an upper opening unit side of the stator back iron 3, and a coil unit 6 installed between the permanent magnets 4 at the lower portion of the movable unit back iron 5 with a constant gap (C). In a state where the stator 1 and the movable unit 2 are separated by the gap (C), as a predetermined distance, when current is applied to the coil unit 6, thrust is generated between the permanent magnets 4 due to the Fleming's left-hand law, and thus the movable unit 2 performs the direct linear motion due to the thrust.

When a control device (not shown) applies current to the coil unit 6, the current is transferred to a coil of the coil unit 6, and magnetic field and thrust are generated between the permanent magnets 4 and the coil unit 6 installed inside the stator back iron 3, thereby moving the movable unit 2 in the front/rear direction. Here, the control device (not shown) controls a movement speed of the movable unit 2 and thrust by the movement according to a winding number of the coil and the supply current.

While synthetic jet ejectors have many advantages, at present, their wide scale commercial use is hindered by the cost of manufacturing these devices, and in particular, by the parts and tooling requirements necessitated by existing synthetic jet ejector designs. Moreover, given the continually shrinking sizes of the devices that serve as hosts to synthetic jet ejectors (and the thermal management systems incorporating them), there is a need in the art for a means by which the dimensions of synthetic jet actuators and synthetic jet ejectors can be reduced. In addition, further improvements are desirable with respect to the expected lifetimes of these devices.

At least some of the foregoing issues are attributable to the bond requirements between the inner perimeter of the diaphragm and the other components of the actuator (e.g., the bobbin), and/or the bond requirements between the outer perimeter of the diaphragm and the other components of the actuator (e.g., the heat sink and/or housing). Frequently, the bond between these components is a silicone-plastic or silicone-metal bond. In addition to the dissimilarity between the materials of these components, the bond interfaces at these locations are subject to considerable stress and represent a common point of failure. This is especially so since the diaphragm is one of the few moving components of these devices.

It has now been found that some of the foregoing infirmities may be addressed by designing the synthetic jet actuator such that one or both of the inner and outer perimeters of the diaphragm are physically clamped in place. Such a configuration avoids the need for an adhesive bond in one or both of these areas, especially in embodiments in which one or both of these areas of the diaphragm are equipped with one or more protrusions (such as one or more annular ridges) that may be engaged by a housing element, a voice coil, a clamp, a ring, or another suitable member.

FIGS. 2-5 illustrate a 2-phase moving motor coil configuration for a synthetic jet actuator. The synthetic jet actuator is constructed with two separate moving motor coils, some distance apart along the axis of the coil former. They are spaced so that when the diaphragm is in its location the farthest away from the pot, the lower coil is in the center of the magnetic inductance field (or where flux density is at a maximum), and when the diaphragm is in its location closest to the motor pot, the top coil is in the center of the magnetic inductance field (or where flux density is at a maximum).

The two coils may be powered separately, so that when one coil is not in the center of the B field no energy is wasted powering it. Also, the amplitude and phase of each coil may be controlled separately, such that the overall motor force could be made more constant over the actuator's stroke, or such that peak BL force occurs at the top or bottom of the stroke.

FIGS. 6-16 illustrate a synthetic jet ejector design in accordance with the teachings herein. The design implements a 2-Piece actuator assembly into a synthetic jet thermal management system. This design does away with the traditional actuator frame, and provides for separate actuator component subassemblies to be installed directly into the cooler housing assembly. This uni-frame construction has many advantages, some of which are (a) lower total cost; (b) elimination of adhesives for sealing the actuator into the housing, or for sealing the motor to the housing; (c) improved airflow and acoustics (no spokes in the way, smaller internal volume); and (d) improved design flexibility and smaller housing external dimensions.

FIG. 17 illustrates a single motor dual piston differential pulsed air actuator in accordance with the teachings herein. The actuator features a moving coil driven diaphragm which is coupled to a second diaphragm through a spring. The masses and spring constant are chosen so that the system resonance is lower than the operating frequency. In this way, the two diaphragms will move out-of-phase, thus minimizing vibration.

FIGS. 18-21 illustrate a dual actuator synthetic jet ejector with a unified magnetic field. In a dual actuator system where actuators are mounted back to back (bottom image), the magnetic field lines of both actuators are partially closed through the bottom of the pots to the sidewalls and partially through the bottom to the adjacent actuator (as drawn in red). This is a source of flux loss, since there are adjacent magnetic layers with opposing magnetization (*). In order to improve this, the present synthetic jet ejector uses a cylindrical (or other suited shape) pot for outer walls (A, upper figure) and a combination of ferromagnetic materials and magnets on the inside of the actuator motor (B). This could be a single magnet or multiple ones, with top plates and slugs as needed. The inner part of the motor would then be suspended by non-magnetic materials, such as a plastic or aluminum or an otherwise pressed or fixed insert (C). This directs the flux without losses through the top and bottom. Furthermore, this design may provide a more uniform magnetic field distribution where the fields for top and bottom actuators, given symmetric geometries, must be nearly identical.

FIGS. 22-23 illustrate a diaphragm with a bellows shape formed in it. An oblong coil is wrapped around the perimeter of the bellows. The coil may be a separate piece, or it may be molded into the diaphragm. The diaphragm bellows-coil is suspended above a permanent magnet. Driving an electric current through the coil in one direction will cause the bellows to shrink and expel air. Reversing the current causes the bellows to expand and fill with air.

FIG. 24 depicts a low profile thermal management system which uses synthetic jets and a spider-like suspension movement. Synthetic jets that are created by a vibrating membrane create more airflow if the cavity behind the membrane (diaphragm) contributes to the air flow. However, in small keep-out-spaces and cyclindrical applications where it is either impossible or impractical to create an access path to the rear diaphragm cavity, the present thermal management system may be utilized. This system uses a standard actuator as it is used in synthetic jet ejectors, but the center disk of the diaphragm is cut open just inside the coil former circumference. A bellows-like seal to the outer ring of the diaphragm is attached to the diaphragm such that makes an airtight separation between outer diaphragm ring (“Zone 1” in drawing) and the inner opening (“Zone 2”). Additionally, it may be necessary in some applications to introduce venting holes in the motor structure or coil former to allow unhindered air flow from the back side of the diaphragm to through the center opening.

As an additional side effect, the center seal can act as a secondary suspension (known as a “spider” in the speaker industry) to assist in controlling the movement of the actuator. This spider may reduce or inhibit rocking of the actuator.

FIG. 25 illustrates an integrated flat coil and flat piston which may be utilized to reduce the axial height of an actuator used in a synthetic jet thermal management system. By making a flat wound voice coil etched or laminated on a flat piston, one may reduce the height of an actuator. The design utilizes all the top fringe flux of a slightly modified from standard actuator motor. However, there is no coil in an air gap, so the overall height of the device may be smaller. A metal such as aluminum may be used as a substrate/piston to reduce the heat buildup in the driven coil.

FIGS. 26-27 depict a modular synthetic jet engine. The concept is to have synthetic jet ejector engines of a fixed diameter, but with different levels of stroke. By making different center sections with different motors, synthetic jet ejectors of varying stroke can be made by selecting diaphragms that are capable of going to much higher stroke than the 3 mm or 5 mm provided by some current models.

FIGS. 28-30 depict a multi-point spring suspension for synthetic jet actuators. The difficulty in designing a reliable and linear actuator lies in creating the right spring forces in the surround or spider structure while achieving design goals for resonant frequency, moving mass and motor parameters. The approach reflected in the present design takes the non-linearity out of that puzzle by providing a linear, manufacturable, durable, tunable spring force design, possibly even with redundancy. At three or more locations underneath the diaphragm leaf-spring like structures in the shape of a diamond or such (could also be snake like) are attached such that neither the attachment points nor the spring itself experiences large stresses. The spring geometry could feature round or sharp corners, multiple stages, or any other geometric features required to make it fit the requirements. The surround would then only serve as a stabilizer and air seal.

FIG. 31 illustrates a perpendicular synthetic jet engine. To accommodate difficult form factors for synthetic jet ejector engines, this alternate construction for the driving of the oscillating membrane in synthetic jet actuators is proposed. Advantages may be found in the integration into replacement light bulbs and there are benefits for vibration control. The idea consists of a bistable flexible membrane that is suspended in such a way that it either likes to rest arched in one orientation or the other. This can be done, for example, by constraining the suspension to be closer together than the membrane is long or wide. Other than that there are few requirements on shape and size. Attention must be paid to the air tightness to a degree on the perimeter of the membrane. The motor that drives the forced oscillations of the membrane is situated with its push/pull axis in line with the average membrane plane, pulling and pushing perpendicular to the orientation that is widely known for speakers. By pulling and pushing we can encourage the membrane to shift positions from one equilibrium position to the other causing the desired oscillation which is needed to produce the synthetic jet action.

FIGS. 32-52 depict a one piece bobbin/diaphragm flange made in accordance with the teachings herein.

The devices and methodologies described above represent notable improvements in synthetic jet technology. However, a number of problems still exist in the art. In particular, many synthetic jet ejectors require the use of tinsel wires or flexible circuit connections between the coil terminals of a moving synthetic jet actuator. These types of connections are prone to breaking or wear, present manufacturing difficulties, and also create surfaces that other components may become caught on or entangled with.

It has now been found that some of the foregoing problems may be overcome through embodiments described herein which avoid the need for tinsel wires or a flexible circuit connection between the coil terminals of a moving coil actuator. This may be accomplished, for example, by utilizing Polymer Thick Film (PTF) conductive inks that may be printed on three-dimensional surfaces using inkjet deposition technologies.

It has further been found that some of the foregoing problems may be overcome by soldering the tinsel leads coming from the diaphragm to the pot magnet structure. The pot magnet structure is preferably in two semicircular halves that do not have electrical contact with each other, thus eliminating contact with the surround.

It has also been found that some of the foregoing problems may be overcome by routing tinsel leads coming from the diaphragm through via holes in the pot structure or frame before reaching the diametric location of the surround, or by using other tinsel routing methodologies as described herein.

FIG. 2 shows a particular, non-limiting embodiment of a printed interconnect for moving actuators in accordance with the teachings herein. As seen therein, a moving coil synthetic jet actuator 201 is provided which comprises a plastic bobbin 203 and actuator basket 205. A pair of terminal pins 207 are inserted into the bobbin 203 and actuator basket 205, and a printed interconnect 209 is provided which extends between the terminal pin in the actuator basket 205 to the terminal pin in the bobbin 203.

Various printable conductive inks may be utilized to form the printed interconnect 209. Preferably, the printable conductive ink is a polymer thick film (PTF) based ink, though conductive inks based on fired high solids compositions or nanoparticles may also be utilized. These inks allow circuits to be drawn or printed on a variety of substrate materials, including polyester or paper, and may contain conductive ingredients or fillers such as powdered or flaked silver, carbon or graphite. These inks may be deposited using inkjet material deposition techniques, which may utilize a print head equipped with piezoelectric crystals.

By utilizing terminal pins 207 inserted into the plastic bobbin 203 and actuator basket 205, the PTF conductive ink 209 can be printed in a trace or plane shape that extends across the roll of the surround 211 and connects the voice coil 213 to the driver board electronics 215. This conductive ink 209 may be bonded to the surround 211 of the actuator 201, thus ensuring that the electrical connection travels in unison with the surround 211 and cannot contact any other parts to cause acoustic artifacts.

The surround 211 can be shaped to minimize bending in any region and to provide high reliability in a dynamic flex environment. Since the surface where the printing of the conductive ink 209 is deposited is on the outside of the synthetic jet actuator 201, this step may be performed after the complete synthetic jet actuator assembly is assembled and (if applicable) ultrasonically welded together. This method is also compatible with automated assembly techniques, since it does not require a tinsel wire or flexible circuit to be carefully woven through the support structure of the synthetic jet actuator.

FIG. 3 depicts a particular, non-limiting embodiment of a device and methodology for routing tinsel leads in accordance herein, and which avoids contact with the surround. In the embodiment depicted therein, a synthetic jet actuator 301 is provided which comprises a diaphragm 303 equipped with a surround 305, a voice coil 307 disposed around a coil former (not shown), a suspension 309, a magnet 311, a top plate 313, and a pot 315. The pot 315, magnet 311 and top plate 313 are split into opposing semicircular halves that are electrically isolated from each other. This may be achieved by the provision of a gap 317 or by the disposition of a dielectric material disposed between the semicircular halves.

First and second portions of tinsel 319 are arranged such that one end of each portion of tinsel 319 is attached to one of the semicircular halves of the pot 315 by way of a solder joint 321, and the other end of each portion of tinsel 319 is attached to a lead on the coil 307. Positive and negative electrical leads 323 are attached to one of the semicircular halves of the pot 315 by way of a solder joint 321. This arrangement eliminates any contact between the tinsel 319 and the surround 305.

FIG. 4 depicts another particular embodiment of a device and method for routing tinsel leads in accordance with the teachings herein which avoid contact with the surround. In the embodiment depicted therein, a synthetic jet actuator 401 is provided which comprises a diaphragm 403 equipped with a surround 405, a voice coil 407 on a coil former, a magnet 411, a top plate 413, and a pot 415. First and second portions of tinsel 419 or wire are routed through passageways 425 provided in the structure of the pot 415, and are held in place by a portion of glue 421 applied to one end of the passageways 425. The tinsel 419 or wires may then be attached to the drive electronics through a bar acting as a single leaf spring, by a helical spring, or by other means.

The passageways 425 are preferably large enough to provide clearance so that the tinsel 419 or wires do not come into contact with the moving parts of the synthetic jet actuator 401. Also, it is preferable that the travel path of the diaphragm 403 be uniform (normal to the voice coil 407). This wire routing method will help improve reliability as well as acoustics due to tinsel noise. As with the previous embodiment, this arrangement may be used to eliminate any contact between the tinsel 419 and the surround 405.

FIGS. 5-6 depict another particular embodiment of a device and methodology in accordance herein which avoids contact between tinsel and the surround. In the embodiment depicted therein, a synthetic jet actuator 501 is provided which comprises a diaphragm 503 equipped with a surround 505, a coil 507 on a coil former, a suspension 509, a magnet 511, a top plate 513, and a pot 515. First and second portions of wire 519, which may be the same wire used to form the voice coil or may be separate (possibly thicker and stiffer) wire leads, are routed through passageways 525 provided in the structure of the pot 515. Each of the first and second portions of wire 519 may be attached to a spring 523 on the other end of the passageways 525. As with the previous embodiment, this arrangement may be utilized to eliminate any contact that might otherwise occur between the tinsel and the surround 505.

FIG. 7 depicts a further particular embodiment of a device and methodology in accordance with the teachings herein which avoids contact between tinsel and the surround. In the embodiment depicted therein, a synthetic jet actuator 601 is provided which comprises a voice coil 603 disposed on a coil former (not shown) and a surround 605. A plurality of tinsel leads 607 are woven into the material of the surround 605. The tinsel leads 607 preferably extend in a non-linear (e.g., curved, tortuous or sinusoidal) path across the surround.

FIGS. 10-11 depict another particular, non-limiting embodiment of a synthetic jet actuator in accordance with the teachings herein. The actuator 701 depicted therein comprises a diaphragm 703 equipped with a surround 705, a coil 707 (see FIG. 11) on a coil former (not shown), a magnet 711 and a basket 715. The actuator 701 incorporates a tinsel-less design that utilizes a carbon nanotube coating 719 on the diaphragm 703 to form a conductive, elastomeric diaphragm 703. The corresponding conventional actuator 702 (without a carbon nanotube coating 719) is shown in FIGS. 8-9.

In a preferred embodiment of this approach, the carbon nanotube coating 719 on the actuator diaphragm 703 is a thin, preferably elastomeric layer that connects the center of the actuator 701 to the edge of the basket 715 along the surface of the diaphragm 703. This provides an electrical connection between the voice coil 707 and a power source, without interfering with the internal geometry or volume of the synthetic jet actuator 701. By contrast, the corresponding conventional synthetic jet actuator 702 depicted in FIGS. 10-11 uses tinsels or flexible circuits 722 to connect the voice coil 707 to the power source. Such use of tinsels or flexible circuits 722 occupies part of the internal volume of the synthetic jet actuator 701, and may present design issues with respect to the internal geometry. By contrast, as noted above, the actuator 701 of FIGS. 10-11 uses a carbon nanotube coating 719 to connect the coil 707 to the outside power source, thus leaving extra internal volume and allowing for more extensive design space.

FIGS. 12-13 illustrate another particular, non-limiting embodiment of a synthetic jet actuator in accordance with the teachings herein which incorporates a tinsel-less design. The actuator 801 depicted therein comprises a diaphragm 803, a voice coil 807 on a coil former 808, an upper outer contact ring 831, a lower outer contact ring 833, an upper inner contact ring 835, a lower inner contact ring 837, and an inner sleeve 839. The diaphragm 803 has opposing upper 841 and lower 843 major surfaces which are electrically conductive. The diaphragm 803 preferably comprises a polymeric material and is preferably metalized on both sides. The inner sleeve 839 is equipped with metal splines 845 which allow the voice coil 807 to be in electrical contact with the upper surface 841 of the diaphragm 803. In addition, the coil former 808, which is preferably not electrically conductive, is equipped with 90° notches to permit the splines 845 in the inner sleeve 839 to press fit with the upper inner contact ring 835.

It will be appreciated that the synthetic jet actuator 801 of FIGS. 12-13 employs a conductive diaphragm 803 that replaces the tinsel connections normally used to make electrical connection to the voice coil 807. The design employs crimp and press-fit fittings to permit automated assembly and long travel of the diaphragm 803 that is often limited by conventional tinsel connections.

FIGS. 14-16 illustrate a particular, non-limiting embodiment of a tinsel-free synthetic jet actuator in accordance with the teachings herein which utilizes a patterned metal speaker interconnect. The synthetic jet actuator 901 depicted therein comprises a diaphragm 903 equipped with a surround 905, and a voice coil 907 on a coil former 909. The actuator 901 includes a patterned metal interconnect 910 for forming an electrical connection between the voice coil 907 and the diaphragm 903.

The diaphragm 903 and surround material 905 are coated (e.g., through vapor deposition, sputtering, plating, or otherwise depositing metal or other conductive materials) with a patterned conductive structure to provide a current path to and from the wires of the voice coil 907. Preferably, electrical connections are made to the metallic coating through the use of a suitable adhesive, by soldering, or the like. The metal coating may be implemented in various shapes and patterns as necessary to achieve the desired electrical and mechanical properties and a suitable lifetime. The electrical contact may be made by pressing, press fitting, crimping, clamping, or through the use of other suitable means.

In a preferred embodiment, an insulating diaphragm 903 is utilized which is coated on one, and preferably on both, sides to provide a current path to and from the voice coil 907. The connection may be made by crimping the top and bottom of the diaphragm 903 to the voice coil former 909. In some embodiments, the entire diaphragm 903 may be made of a material that can be doped, irradiated or otherwise treated so as to change its properties from conductive to non-conductive (or from non-conductive to conductive) to provide two distinct current paths to the voice coil 907.

The foregoing methods may also be combined with other methods, such as the use of tinsel wires, to achieve desired electrical and mechanical properties and a suitable lifetime. Moreover, to aid in current routing, the voice coil 907 may be coated or patterned using methodologies such as those described above.

FIG. 17 illustrates another particular, non-limiting embodiment of a synthetic jet actuator in accordance with the teachings herein. The actuator 1001 depicted therein comprises a voice coil 1003, a diaphragm 1005, and one or more portions of tinsel 1007 which extend from the voice coil 1003 to the edge of the diaphragm 1005. The synthetic jet actuator 1001 depicted utilizes a spiral routing scheme for the tinsel 1007 so as to minimize flexing and improve reliability.

It is typically necessary to connect the moving voice coil of a synthetic jet actuator to a fixed point for external electrical power to drive the coil. The wires used for this connection are specially designed for long flexure life. The synthetic jet actuator 1001 of FIG. 17 is advantageous in that the tinsel 1007 or wires utilized for this connection minimize flex stress concentration, such as at the termination points, thus helping to improve reliability. In particular, by using the tinsel routing scheme described herein, the flexing is distributed along an extended length and minimizes the flexure of any point along the tinsel 1007. This approach also helps to prevent resonant looping motion.

The diaphragm 1005, which is driven by the motion of the voice coil 1003, often is made with reinforcing ribs or rings molded into it to give more uniform motion, to prevent buckling, and to add strength. By molding the rings as spirals from the coil connection points near the center to the outer rim of the diaphragm 1005, the strength benefits can be obtained. Moreover, by routing the tinsel 1007 along the spirals (e.g., next to the ridge of the spirals or between these ridges), the tinsel 1007 is flexed only a very small amount, and uniformly along the entire path from the voice coil 1003 to the fixed termination point. Hence, instead of having the end-to-end displacement of the tinsel 1007 occur over approximately one radial length, it can occur over 2πx the radial length or longer if the spiral makes several revolutions between the center and the outer perimeter of the diaphragm 1005.

Several variations are possible with the foregoing embodiment. Typically, at least two tinsels will be required to connect the voice coil to an external power source. In some embodiments, a single spiral may be provided in the diaphragm with both tinsels run adjacent to each other, and with the tinsels electrically insulated from each other. In other embodiments, a separate spiral may be provided for each tinsel. The tinsel may be disposed on the top or bottom surface of the diaphragm, or both. One or more tabs may be provided on the rim of the diaphragm to make electrical connections to the tinsel.

In some embodiments of the devices and methodologies described herein, the voice coils utilized may be powered through electrical induction. In accordance with such methods, electrical power is delivered to the voice coil without tinsels (e.g., wirelessly) by using an electric inductance effect. An external coil is used to emit the AC magnetic field, which in turn is picked up by the voice coil or a secondary pick up coil to power the voice coil.

While thermal management systems which utilize synthetic jets to enhance cooling have many desirable properties, further improvements in these devices are required to meet evolving challenges in the art.

For example, at present, many synthetic jet actuators require a separate calibration step before the actuator is installed inside the housing of a thermal management device. Since calibration requires the use of displacement sensors to detect the motion of the actuators and adjust the control values to meet a target displacement amplitude, at present, calibration typically occurs when the actuator is outside of the housing so that inexpensive sensors can be used and so that aiming of these sensors is simplified.

However, it has now been found that, by utilizing Ther optic reflectance sensors such as those produced by Phiftec (www.philtec.com), these displacement measurements can be made while the actuator/engine is inside the housing by providing a small hole in the housing situated over the target region of the actuator (see FIG. 2). The sensor head consists of a fiber optic bundle encased in a milled metal assembly. This milled metal assembly has a shaft and flange that can be sized to mate with a hole in the housing and position the sensor head at the precise location and depth needed to make the displacement measurement. Since the hole in the housing is small and is effectively sealed when the sensor is inserted, no changes to dynamic loading of the actuator occur and the calibration is performed tinder the exact conditions the device is expected to operate under. In the case of an engine that is integrated into a heat sink such as a light bulb replacement the metal core board which carries the LEDs and attaches to the heat sink can be used to seal this hole on one side of the engine.

After calibration, the sensor is removed, and the hole can be sealed by means of a membrane with pressure sensitive backing, a screw, plastic plug, caulk/gap filler, or deformation of a plastic feature on the housing (heat staking) The benefits of this approach are reduced assembly/handling time, improved calibration accuracy, and higher confidence in device operation after final assembly.

FIG. 3 depicts an integrated circuit (ASIC) that may be used to drive an LED array for lighting purposes and also drive the actuators of a synthetic jet ejector based cooling system to provide cooling for those LEDs with minimum space and cost. For the purposes of LED light bulbs intended to replace existing incandescent light bulbs several aspects are important:

1) Size/form factor

2) Cost

3) Power factor

A single IC can address these 3 factors in a SynJet cooled LED lighting application.

To minimize the need for large charge storage capacitors and achieve maximum power factor, both the synthetic jet ejector and the LED array will be driven with a waveform that has a sinusoidal current at the same frequency as the AC line input (50 or 60 Hz). Synchronization with the line power frequency can be achieved with a zero crossing detector.

The block diagram of FIG. 3 shows one possible implementation of this type of system. The core logic of the LED and SynJet controller will be powered from a linear regulator that receives input power from the rectified version of the input line power. The input power requirements for this core logic are small so only a small holdup capacitor is needed and power dissipation in the linear regulator is low. By having a direct connection to the input power waveform, it is also possible for the synthetic jet ejector control portion of the IC to react immediately to input changes from TRIAC based dimmers, rather than indirectly through the OV-5V control input that is present on existing stand-alone synthetic jet ejector driver ASICs.

The LED array may be powered from a non-isolated buck regulator that is controlled by the ASIC. The ASIC would monitor the current through the LED array and use this measurement to maintain a constant current regulation through the LEDs. The forward voltage developed across the LED array would not be well regulated due to variations in LED characteristics, but would provide a lower voltage intermediate node that could be provided to an H-Bridge driver. This HBridge driver would drive the actuators in the synthetic jet ejector cooler and would also be controlled from the ASIC.

Monitoring the forward voltage of the LEDs could also potentially be used as a means of inferring their temperature and this information could be used to scale back the synthetic jet ejector cooling and improve acoustics when cooling is not needed, Because the controller is regulating the measured current through the LED array, no flicker in the light output wilt result from the HBridge tapping current from the buck supply. This system may be utilized to produce a low cost, low part count implementation of a LED controller and synthetic jet ejector driver that leverages feature advantages that can only be achieved when the IC has control over the entire system.

FIG. 4 depicts an LED lamp that is powered by 110/220VAC Mains power and is cooled by a synthetic jet ejector which is also powered by 110/220 V AC Mains power. The way this is accomplished may be utilized to produce a simple, reliable, low cost device.

With reference to FIG. 4, the following comments may be made with respect to the circuit description:

• • 1. PI plugs into the standard wall power outlet which provides either 110VAC at 60 Hz or 220VAC at 50 Hz,
  • 2. F1 provides a current limit fuse for safety. Its value will depend upon the power required by the LED array primarily. S1 selects the operating line voltage and configures T1 input windins and the LED array for proper operation at the voltage selected.
  • 3. T1 steps down the mains line voltage to a low voltage suitable to drive the synthetic jet ejector cooler, typically in the range of 5 to 12 VAC at the line frequency.
  • 4. R1 and R2 may be optional in some designs. They are used to set the synthetic jet ejector drive voltage and current to the value required by the product application. Additionally, PTC type resistors may be used to provide automatic compensation of the synthetic jet ejector drive voltage with changes in temperature.
  • 5. R3 and R4 are LED current limiting resistors and are selected based on the particular LED selected, and the LED operating voltage (110 or 220VAC). Note: Lamps intended to be powered by 110VAC use LEDs rated for 110VAC operation while lamps intended for 220VAC must be outfitted with, either two II OV AC LED arrays in series or a 220 V AC array.
  • 6. The Syn Jet's internal actuators typically employ a 8 +/− 1 ohm DCR coils and while a dual actuator configuration is shown here, the design could use a single or other multiply configurations.
  • 7. Since there are no “active” circuits in this design, generally no EMI filters are required, however, it may be desirable to include an AC line filter on the input to minimize the amount of audible band noise that is conducted to the actuators from the Mains line power in applications where acoustic noise levels must be minimized.

The foregoing circuit has the following advantages:

• • 1. The entire lamp and cooling drive employs the minimum number of components resulting in high reliability and lower overhead costs associated with engineering, documenting, purchasing and stocking many more components used and current electronic circuit designs.
  • 2. The low currents (usually in the range of 20 to 50 mAmps) used to drive the LEDs results in lower LED operating temperatures due to smaller I²R losses even though much smaller wire may be used than is used in the typical high brightness LEDs which have typical forward current in the range of 1 ampere. This also reduces the amount of cooling required by the LEDs, allowing smaller heat sinks and smaller synthetic jet ejectors.
  • 2. The synthetic jet actuators can be fabricated with an FO that will result in and F1 at or very near the mains line frequency, thereby minimizing the drive current required and the size and cost of T1.
  • 4. Acoustic tests on a prototype show acoustic sound pressure levels are very similar to those achieved with more complex electronic driver circuits (i.e. <25 dba at 60 Hz) without any filtering of any kind. The parasitic capacitors that are part of every AC transformer seem to help to form an intrinsic low pass filter that reduces conducted noise levels to the synthetic jet actuators. Versions built for International use at a mains line frequency of 50 Hz will sound even more quiet than the 25 dba achieved at 60 Hz.

FIGS. 5-9 illustrate a method which uses the changing capacitance between moving conductive plates to determine the relative position of the moving diaphragm (one of the plates) to a fixed plate such as a housing cover or base plate. The varying capacitance can be used with appropriate signal analysis electronics for feedback control of the motion, to predict end of travel conditions, to convert non-linear motion into linear motion, etc.

In a preferred embodiment depicted, a single conductive aluminum disk has been attached to the moving diaphragm, and a two piece conductive aluminum disk (half moons) has been attached to the underside of a cover placed above the diaphragm. As the diaphragm moves, the capacitance as measured between terminals on the half moon changes creating a measurable position signal.

It is to be noted that, based on the small values of capacitance and the change, this is likely to require the following:

(a) a very high Z input buffer amplifier; or

(b) the use of a 1-10 MHz signal and filter; or

(c) possibly as oscillator with this C as the frequency tuning, plus a counter or other suitable circuit to measure small C and delta C.

FIGS. 10-11 depict a synthetic jet actuator control with integrated IR sensing of target temperature. While this concept was developed for use in synthetic jet electronic actuator control, it could be applied in other areas where electromagnet transducers, fans or motors are in use to cool a target device. FIG. 10 illustrates a synthetic jet example configuration, while FIG. 11 illustrates how other devices such as fans may be controlled using this method.

The primary drive signal is a Pulse Width Modulated (PWM) signal that is generated by the system controller or microprocessor. For multiple targets, addition PWM or similar control signals must be generated by the same or multiple controllers/microprocessors.

The IR sensor is mounted in the Syn Jet housing so as to be aimed at the target area to be controlled. The output signal from the IR sensor is connected to the drive electronics so it can measure the signal amplitude (voltage, current or frequency depending on the specific type of sensor used). The controller makes periodic measurements of the IR senor signal amplitude then per the on board software control algorithm, adjusts the output drive signal to affect an increase or decrease in cooling so as to maintain a temperature equal to or below a required temperature limit that assures proper operation of the target device.

The sensor mounting can be a “molded in” design or a “stick on” up-grade, The sensor cam be in a hard fixed position mount or in a mount that permits “aiming” it at the target.

With reference to FIG. 11, this feature could be implemented on fans in many ways including but not limited to:

(a) a “stick on” sensor that is connected to external Fan control circuit able to measure IR sensor.

(b) a side mounted sensor that is connected to the fans built in control circuit, or external control circuit.

(c) a combination “stick on” or “mold in” fan control circuit with integral IR temperature sensor.

(d) a sensor in a pivotable or flexible aimable “stick on” mount.

The foregoing approach has several advantages. These include:

(a) There is no need to install thermocouples or other temperature sensors on the target device and connect them to the control circuit.

(b) Small size and low cost

(c) Can be easily added as a stand-alone up-grade, just provide appropriate power connection.

FIGS. 12-14 illustrate a synthetic jet thermal management device with target protection/control. The device depicted has the ability to monitor target device temperature and/or power consumption and interrupt target power if a failure/over-temperature condition occurs and/or indicate to a host system controller via a logic level change or a text message indicating the problem.

By integrating the monitoring and I or target power switching functions into the synthetic jet controller, the benefits of the synthetic jet solution are greater, the overall cost is lower and the target device is fully protected by ‘fail safe operation’ should a failure occur in the synthetic jet ejector or target device occur.

FIG. 12 depicts the circuitry for power interruption upon failure condition detection.

FIG. 13 depicts the circuitry for target power monitor of failure condition detection. It is to be noted that the current sensor can be located in the target return instead of in the positive side. It is also to be noted that the target status signal can be used to drive an LED or audio alarm to indicate a problem. Finally, it is to be noted that UART can be used to output a text error message to the host controller.

FIG. 14 depicts a combination target power monitor of failure condition detection with a power switch target power. It is to be noted that the current sensor can be located in the target return instead of in the positive side. It is also to be noted that the target status signal can be used to drive an LED or audio alarm to indicate a problem. It is also to be noted that UART can be used to output a text error message to the host controller. Finally, it is to be noted that a sense FET transistor may be used to combine both the current sensing and power switching functions into a single component.

FIGS. 15-16 illustrate a method for tracking changes in synthetic jet resonance. In order to maximize synthetic jet ejector performance, it is important to operate the air-moving actuators at the maximum possible displacement and frequency. Power consumption of a synthetic jet ejector operating at a given displacement is a strong function of frequency,

In the typical power vs frequency curve (see the black trace in FIG. 15), it can be seen that there is significant power efficiency advantage in operating at the system resonant frequency of about 110 Hz. Unfortunately, the resonant frequency is a strong function of operating temperature, and the age of the actuator.

A method is provided herein for finding and tracking the resonant frequency so that as temperature and operating conditions change, the system can always be operated at the resonant frequency. The method relies upon the rapid change of input impedance phase that occurs at the resonant frequency. The plot in FIG. 16 shows the input impedance of a typical cooler. Note that the phase of the input impedance changes abruptly from positive to negative at resonance. This makes it easy to detect resonance in the presence of noise by the following method:

1. Set a register equal to zero.

2. Find the time at which the input voltage crosses through zero volts, call this t_v.

3. Find the time at which the input current crosses through zero amps, call this t_i.

4. If tv<ti then the phase is negative otherwise the phase is positive.

5. Increment the register if the phase is positive otherwise decrement the register.

6. Repeat steps 2 through 6 a large number of times (typically a few hundred).

7. If the register is positive, the phase is positive, the system is operating below resonance.

so the drive frequency is increased.

8. Repeat steps 1 through 7 continuously to find and track resonance.

It is important as resonance is tracked to make appropriate adjustments to the back-emf target which the displacement control-loop is using to maintain displacement.

The target is proportional to frequency, so the target must be increased or decreased as the frequency is varied.

It is also important to implement voltage, current and power limiting. The power amplifier driving the cooler must not be operated beyond its limits. If this occurs, displacement control will be lost, and/or the amplifier and/or cooler may be damaged. Limiting can be implemented in the control software by reducing the drive voltage when limit conditions are detected. This will typically happen at lower temperatures (when the cooler resonance is higher in frequency, and when the actuator suspension is stiffer/more lossy.

It has also been found that the use of a piezoelectric film co-molded or integral to the suspension or diaphragm of an actuator or transducer may allow active feedback and suspension and/or motion control of a device.

With reference to FIG. 17, an optical position sensor is described for dynamic detection of the diaphragm's position in the actuator housing. This detector uses an optical beam emitter emitting a narrow beam that strikes a small, highly reflective area on the surface of the diaphragm. The geometry is such that a maximum signal is received by the detector when the actuator diaphragm is in the maximum down position. In all other positions of the diaphragm, the signal received is smaller.

By detecting the Max Down position, the diaphragm can be controlled to prevent “bottoming out” with related acoustic & mechanical loss of performance. This inventions allows repeatable measurement of an individual actuator's Max Down position, and is generally applicable to compensate for production variations, temperature and ageing effects while allowing full range of motion for best cooling. The emitter/aperture assembly may be separate or integrated into the housing, similarly for the detector assembly.

Although the detector will work with the emitter and detector mounted in various positions, by mounting them on the periphery of the housing and in an upper corner, they will not be a constraint on the diaphragm motion nor the maximum thickness of the overall actuator/housing assembly. They are in an area above the surround, and its motion does not encroach.

This sensor includes extensions to include multiple emitters and detector assemblies to detect other desired positions, such as Neutral or Max Up. The assemblies may be mounted at 90 degrees from each other (in the case of two assemblies), one could measure Max Down, and the Max Up. Also, one emitter could, with signal conditioning, work with two detectors, as a simple extension of this concept. Rate of change of the detected signal can give velocity information, and with two detectors an average velocity can be measured.

The reflective single spot or stripe in the center of the diaphragm is described above. This approach can be extended to other configurations. The reflective material can be applied in multiple stripes or other configurations to give diaphragm position feedback information.

Applying single or multiple emitter/detector assemblies also gives additional signals for determination and compensation for changes in diaphragm/surround spring constant and B-field variations.

The above description of the present invention is illustrative, and is not intended to be limiting. It will thus be appreciated that various additions, substitutions and modifications may be made to the above described embodiments without departing from the scope of the present invention. Accordingly, the scope of the present invention should be construed in reference to the appended claims.

Claims

1-19. (canceled)

20. A synthetic jet actuator, comprising: a diaphragm equipped with a surround;a voice coil having first and second terminal portions;a pot structure having first and second portions which are electrically isolated from each other;a first portion of tinsel having a first end which is in electrical communication with said first terminal portion of said voice coil, and a second end which is in electrical communication with said first portion of said pot structure; anda second portion of tinsel having a first end which is in electrical communication with said second terminal portion of said voice coil, and a second end which is in electrical communication with said second portion of said pot structure.

21. The synthetic jet actuator of claim 20, wherein said first and second portions of said pot structure are spaced apart from each other.

22. The synthetic jet actuator of claim 20, wherein said first and second portions of said pot structure have a dielectric material disposed between them.

23. The synthetic jet actuator of claim 20, further comprising a magnet having first and second portions which are electrically isolated from each other.

24. The synthetic jet actuator of claim 23, wherein said first and second portions of said magnet are spaced apart from each other.

25. The synthetic jet actuator of claim 23, wherein said first and second portions of said magnet have a dielectric material disposed between them.

26. The synthetic jet actuator of claim 23, wherein said magnet is disposed on, and in contact with, said pot structure.

27. The synthetic jet actuator of claim 23, further comprising a top plate disposed on said magnet, said top plate having first and second portions which are electrically isolated from each other.

28. The synthetic jet actuator of claim 27, wherein said first and second portions of said magnet are spaced apart from each other.

29. The synthetic jet actuator of claim 27, wherein said first and second portions of said magnet have a dielectric material disposed between them.

30. The synthetic jet actuator of claim 20, wherein said voice coil and said pot structure are spaced apart from said diaphragm.

31. The synthetic jet actuator of claim 20, wherein said pot structure is annular in shape.

32. A synthetic jet actuator, comprising: a diaphragm equipped with a surround;a voice coil having first and second terminal portions;a pot structure having first and second passageways defined therein;a first conductive element which extends through said first passage way and which is in electrical communication with said first terminal portion of said voice coil; and a second portion of tinsel which extends through said second passage way and which is in electrical communication with said second terminal portion of said voice coil.

33. The synthetic jet actuator of claim 32, wherein said voice coil and said pot structure are spaced apart from said diaphragm.

34. The synthetic jet actuator of claim 32, wherein said pot structure is annular in shape.

35. The synthetic jet actuator of claim 32, wherein at least one of said first and second conductive elements is a portion of tinsel.

36. The synthetic jet actuator of claim 32, wherein each of said first and second conductive elements is a portion of tinsel.

37. The synthetic jet actuator of claim 32, wherein said voice coil comprises a first wire, and wherein at least one of said first and second conductive elements comprises said first wire.

38. The synthetic jet actuator of claim 32, wherein said voice coil comprises a first wire, and wherein both of said first and second conductive elements comprises said first wire.

39. The synthetic jet actuator of claim 32, wherein said voice coil comprises a first wire, and wherein at least one of said first and second conductive elements comprises a second wire of larger caliper than said first wire.

40-112. (canceled)