US20110108051A1 - Ultrasonic Hairstyling Device - Google Patents

Abstract

A device for styling hair includes a handle and a barrel extending from the handle. The barrel has a styling surface spaced from the handle, and the styling surface is configured for winding the hair around the barrel. The device further includes a heating element in thermal communication with the barrel to transfer heat to the hair via the styling surface of the barrel, and an ultrasonic transducer configured to generate ultrasonic vibrations. The ultrasonic transducer is disposed within the barrel to transmit the ultrasonic vibrations to the hair via the styling surface of the barrel.

Description

CROSS-REFERENCE TO RELATED APPLICATION
• This application claims the benefit of U.S. provisional application entitled “Ultrasonic Curling Iron,” filed Oct. 6, 2009, and assigned Ser. No. 61/249,074, and U.S. provisional application entitled “Ultrasonic Flat Iron,” filed Oct. 28, 2009, and assigned Ser. No. 61/255,657, the entire disclosures of which are hereby expressly incorporated by reference.
BACKGROUND OF THE DISCLOSURE
• 1. Field of the Disclosure
• The present disclosure is generally directed to hairstyling devices, and more particularly to curling irons and flat irons.
• 2. Description of Related Art
• Traditional techniques for styling hair involve the application of heat. Attempts to style hair faster or create more robust holds have been based on increasing the amount of heat applied to the hair. The heat acts upon water molecules contained in the center of the hair. Restructuring the hydrogen bonds between the water molecules allows the hair to retain the desired styling.
• Unfortunately, elevated amounts of applied heat tend to dry and damage hair, rendering the hair difficult to style, reducing shine, and ultimately resulting in unhealthy hair. Excessive heat can damage the outer layers of the hair, i.e., the cuticle, resulting in split ends. The hair becomes more limp and unable to hold desired styling, once the cuticle and inner shaft of the hair lose the water content that would otherwise provide strength.
SUMMARY OF THE DISCLOSURE
• In accordance with one aspect of the disclosure, a device for styling hair includes a handle, a barrel extending from the handle and having a styling surface spaced from the handle, the styling surface being configured for winding the hair around the barrel, a heating element in thermal communication with the barrel to transfer heat to the hair via the styling surface of the barrel, and an ultrasonic transducer configured to generate ultrasonic vibrations. The ultrasonic transducer is disposed within the barrel to transmit the ultrasonic vibrations to the hair via the styling surface of the barrel.
• The handle and the barrel may be oriented along a longitudinal axis, and the ultrasonic transducer may be oriented along the longitudinal axis such that the ultrasonic vibrations are generated in a direction parallel to the longitudinal axis. The ultrasonic transducer may then include a horn with a rim in contact with an interior surface of the barrel that defines an annular interface through which the ultrasonic vibrations travel.
• In some cases, the ultrasonic transducer includes a horn in contact with the barrel. Alternatively or additionally, the barrel may terminate at an end cap, and the ultrasonic transducer may include a horn in contact with the end cap. Alternatively or additionally, the barrel has a length equal to a wavelength of the ultrasonic vibrations or a multiple of the wavelength.
• In accordance with another aspect of the disclosure, a device for styling hair includes an elongate housing defining a handle grip surface and a styling surface spaced from the handle grip surface, a plate pivotally coupled to the elongate housing to clamp the hair between the plate and the styling surface, a heating element in thermal communication with the styling surface or the plate to transfer heat to the hair, and an ultrasonic transducer configured to generate ultrasonic vibrations. The ultrasonic transducer is disposed within the elongate housing to transmit the ultrasonic vibrations to the hair via the styling surface.
• The elongate housing may be oriented along a longitudinal axis. The ultrasonic transducer may be oriented along the longitudinal axis such that the ultrasonic vibrations are generated in a direction parallel to the longitudinal axis. The ultrasonic transducer may then include a horn with a rim in contact with an interior surface of the elongate housing that defines an annular interface through which the ultrasonic vibrations travel.
• The ultrasonic transducer may include a horn in contact with the elongate housing. The elongate housing may include a barrel that terminates at an end cap. The plate may then be curved to match a curvature of the barrel, and the ultrasonic transducer may then include a horn in contact with the end cap.
• The device may further include a wand pivotally coupled to the housing. The plate may be mounted on the wand, and the plate and the styling surface may be flat.
• In some cases, the device further includes a flat plate mounted on the elongate housing. The flat plate may then have a first side that defines the styling surface and a second side in contact with the ultrasonic transducer. The ultrasonic transducer may be oriented in alignment with the elongate housing. The ultrasonic transducer may include a horn adapter to direct the ultrasonic vibrations laterally toward the flat plate. Alternatively or additionally, the flat plate has a length equal to a wavelength of the ultrasonic vibrations or a multiple of the wavelength.
• The elongate housing may include a handle that defines the handle grip surface and may further include a barrel extending from the handle and defining the styling surface.
BRIEF DESCRIPTION OF THE DRAWINGS
• Objects, features, and advantages of the present invention will become apparent upon reading the following description in conjunction with the drawing figures, in which like reference numerals identify like elements in the figures.
• FIG. 1 is a perspective, cutaway view of an exemplary curling iron constructed in accordance with one or more aspects of the disclosure.
• FIG. 2 is a perspective, end view of the curling iron ofFIG. 1 to depict an exemplary ultrasonic transducer in greater detail.
• FIG. 3 is a perspective view of the ultrasonic transducer ofFIG. 2 to depict one or more aspects of the disclosure relating to embodiments having a Langevin transducer configuration.
• FIG. 4 is a cross-sectional view of a housing of the curling iron shown inFIGS. 1 and 2 taken along the lines4-4 ofFIG. 2 to depict the mounting of the ultrasonic transducer ofFIGS. 1-3 within the housing in an axial orientation and barrel position in accordance with several aspects of the disclosure.
• FIG. 5 is a schematic diagram of an exemplary drive circuit for controlling the operation of the ultrasonic transducer ofFIGS. 2-4.
• FIG. 6 is a perspective, cutaway view of an exemplary flat iron constructed in accordance with one or more aspects of the disclosure.
• FIG. 7 is a perspective, partial view of an arm of an exemplary flat iron constructed in accordance with another embodiment.
• FIG. 8 is a perspective view of an exemplary ultrasonic transducer of the flat irons ofFIGS. 6 and 7.
• FIG. 9 is a cross-sectional view of an arm of a flat iron similar to the view shown inFIG. 4 to depict an exemplary mounting of the ultrasonic transducer ofFIG. 8 within the arm.
• FIG. 10 is a schematic diagram of another exemplary drive circuit for controlling the operation of the ultrasonic transducers of the disclosed hairstyling devices.
• FIGS. 11A and 11B are graphical diagrams of data collected during energy transmission testing of the disclosed hairstyling devices.
• FIG. 12 is a perspective, end view of another exemplary curling iron constructed in accordance with an alternative embodiment in which an ultrasonic transducer is secured to an exterior barrel surface.
• FIG. 13 is a perspective view of an alternative transducer mounting configuration in which a modified Langevin transducer transfers vibration energy radially through a flattened horn surface.
DETAILED DESCRIPTION OF THE DISCLOSURE
• The disclosure is generally directed to an ultrasonic hair styling device that transmits ultrasonic vibrations to the hair to reduce the amount of heat applied for styling. The disclosed devices generally improve hairstyling by decreasing the time and temperature level of the applied heat, thereby improving the overall health of the hair, increasing shine, and improving styling hold. In this way, users of the disclosed devices can style hair faster and create longer-lasting holds without having to resort to the application of more heat. Instead of conventional styling heat levels of 400-450° F., use of the disclosed devices has effectively styled hair at temperature levels around about 250° F. to about 350° F.
• The ultrasonic vibrations generally apply energy to the hair via the styling elements or surfaces in contact with the hair. The energy from the ultrasonic vibrations then adds to the energy applied by the heat such that the total energy reaches a level appropriate for styling. The energy from the ultrasonic vibrations also results in improved heat distribution in the styling elements or surfaces, which may also help reduce the time needed to achieve and set the desired styling. In hairstyling devices involving wet-to-dry operation, the ultrasonic vibrations lead to faster drying and, thus, lower amounts of applied heat. For these reasons, the likelihood or risk of damage to the hair decreases.
• Although described below in connection with curling irons and flat irons, the ultrasonic vibrations may be useful in connection with a variety of hair styling tools or techniques. Thus, the disclosed hair styling devices are not limited to curling irons or flat irons. Nonetheless, in some cases, the ultrasonic vibrations may be transferred while the hair is clamped or otherwise fixed between styling tools or elements. In this way, contact between the vibrating elements of the disclosed devices in the hair is ensured.
• Turning to the drawing figures,FIG. 1 depicts a curlingiron20 having anelongate housing22. A base portion of thehousing22 forms ahandle24 from which abarrel26 of thehousing22 extends. Thehandle24 provides ahandle grip surface28 for an operator of the curlingiron20 to grasp during use. Thebarrel26 provides astyling surface30 spaced from thehandle grip surface28 to avoid or minimize unwanted user contact with thestyling surface30. Thestyling surface30 is generally configured for winding hair to be styled around thebarrel26 to form curls or other styling effects. To that end, theelongate housing22 and each portion thereof may be generally cylindrically shaped, although thehandle24 and thebarrel26 may be shaped otherwise and, moreover, need not be similarly shaped. Thehandle24 and thebarrel26 are configured such that thehousing22 is shaped as a wand or an arm.
• Thehandle24 and thebarrel26 may be integrally formed to any desired extent. Thehandle24, for instance, may include a rubberized, plastic, or other grip (not shown) mounted upon an extension of thebarrel26. In other cases, one or both of the portions of theelongate housing22 may be formed via interlocking or interconnected half- or other shells. For example, thehandle24 may include a molded, two-piece construction consisting of two matching, half-cylinder plastic covers secured to one another via one or more screw or other fasteners. These and other parts of thehandle24 may be constructed of a variety of materials other than plastics, including stainless steel. Thebarrel26 may include one or more components constructed of stainless steel, iron, aluminum, or other thermally conductive materials. In some cases, thehandle24 and thebarrel26 are discrete structures connected to one another via one or more fasteners, one or more snap-fit connectors, or some other coupling mechanism. Alternatively, thehandle24 may be configured as a sleeve that fits over a tube or other housing that runs the length of the device to also form thebarrel26.
• Thehandle24 includes a number of user interface or control elements. To this end, thehandle24 may have a non-circular cross-sectional shape. The example shown, for instance, has a longitudinal ridge31 that runs the entire length of thehandle24. The ridge31 presents a panel or other section of thegrip surface28 for the user interface or control elements. The ridge31 and other projections may also improve thegrip surface28. In other cases, thehandle24 may have an oval or other non-circular cross-sectional shape to configure thegrip surface28 in a desired manner. Similarly, thebarrel26 need not have a circular cross-sectional shape as shown in the event that, for instance, a different curl or other styling effect is desired.
• Both thehandle24 and thebarrel26 are configured as hollow tubes to accommodate a number of functional elements, such as electrical components and circuitry. These components generally support the operation of the curlingiron20, which includes ultrasonic vibration as described below. In this example, thehandle24 houses acircuit board32 shaped as an elongate strip oriented lengthwise and mounted within thehandle24 via one or more screw or other fasteners. Thebarrel26, in turn, houses one ormore heating elements34 and anultrasonic transducer36. Theheating elements34 are generally disposed within thebarrel26 in thermal communication with thestyling surface30 to transfer heat to the hair wound around thebarrel26. In this example, eachheating element34 includes a thermallyconductive strip38 disposed and extending along an interior wall of thebarrel26. Eachstrip38 may have any desired shape, including, for instance, a flat or curved plate. Both theheating elements34 and theultrasonic transducer36 are generally oriented lengthwise within thebarrel26.
• Eachheating element34 may be conventionally constructed and configured. Suitable heating element materials include ceramics and metals. In this example, eachheating element34 includes an elongate, flat, ceramic plate disposed upon a flat or other mount inside thebarrel26. Each mount may be constructed of a heat conductive material to encourage the transfer of heat from theheating element34 to thestyling surface30 of thebarrel26. Thebarrel26 in this case has a pair of opposing heating elements positioned lengthwise within thebarrel26. Eachheating element34 may run the length of thebarrel26 or any desired segment thereof. In this example, eachheating element34 extends from an inner end of thebarrel26 to theelectronic transducer36, stopping short of the outer end of thebarrel26 as shown. Any number ofheating elements34 may be disposed within thebarrel26 at a variety of locations, including those that reach the outer end of thebarrel26 as with, for instance, the embodiment described below. One potential advantage of the disclosed hair styling devices, however, is that the number, size, or intensity of theheating elements34 may be reduced as a result of the application of ultrasonic vibrations, as described below. Nonetheless, the disclosed hair styling devices may still include a conventional amount of heating capacity to provide the operator with various operational options, including a non-ultrasonic option. In these and other ways, the curlingiron20, for instance, may be configured to present a range of possible heating levels to the operator to accommodate different hairstyling requirements arising from, for instance, differing hair thickness.
• The curlingiron20 also includes aclip assembly40 pivotally secured to theelongate housing22. Theclip assembly40 may include one or more springs or other elastic elements to bias theclip assembly40 toward thebarrel26 to thereby clamp and hold the hair in position between thestyling surface30 of thebarrel26 and aplate42 of theclip assembly40. Theplate42 extends lengthwise along thebarrel26 and has astyling surface44 on an inward facing side. Theplate42 is generally capable of moving thestyling surface44 into a position facing or opposite from thestyling surface30 of thebarrel26. Thebarrel26 and theplate42 may be configured so that the shapes of the styling surfaces30 and44 are matching or complementary. For instance, theplate42 may be curved to an extent to match the curvature of thebarrel26.
• In this example, theplate42 is pivotally coupled to theelongate housing22 via apivot link46 of theclip assembly40. Thepivot link46 has one or more ends that terminate at a respective pivot joint or hinge48 at which theclip assembly40 is secured to theelongate housing22. In this example, theclip assembly40 has two diametrically opposed pivot joints48 at an inner orproximate end50 of thebarrel26. Each pivot joint48 includes a pin, bolt, orother pivot element52 that passes through thepivot link46 and thebarrel26. Thepivot link46 generally extends laterally outward from thebarrel26 to form alever54, which may, in turn, include agrip surface56 to facilitate operator engagement during operation. The manner in which theclip assembly40 is pivotally coupled may vary considerably. For instance, in some cases, theclip assembly40 is secured to thehandle24.
• The shape, construction, and other characteristics of thehandle24, thebarrel26, and theclip assembly40 may vary considerably from the example shown. A variety of different configurations and constructions are well suited for use with the ultrasonic features of the disclosed hairstyling devices.
• Thecircuit board32 includes a number ofcircuit elements58 to control eachheating element34 and theultrasonic transducer36. The circuitry responsible for controlling the heating and ultrasonic vibrating functions may be integrated to any desired extent. In some cases, a separate circuit board may be disposed within theelongate housing22 to handle one of the two functions alone. In any event, thecircuit elements58 may be disposed in a location within the elongate housing22 (e.g., near a base end of the handle24) to avoid the heat generated by theheating elements34. Because one or more of thecircuit elements58 may also constitute sources of heat, thecircuit elements58 may be nonetheless configured for operation in an elevated temperature environment. Temperature levels within thehousing22 may exceed normal operating temperatures even though thecircuit elements58 are spaced from theheating elements34. To help dissipate heat, one or more of thecircuit elements58 may include aheat sink60. For example, one or more copper elements may be disposed upon acircuit board32 or a respective one of thecircuit elements58. In some cases, the curlingiron20 may include a barrier, divider, wall, or other element within thehousing22 to block the transmission of heat from thebarrel26 to the components within thehandle24.
• Thecircuit board32 is coupled to a power source via apower cord62. In other examples, thecircuit board32 is coupled to a battery or other portable power source, which may be rechargeable via, for instance, thepower cord62. Thecircuit board32 is also coupled to one or more control orinput elements64. One or more of thecontrol elements64 may be directed to activating and deactivating the curlingiron20 or one or more operational features thereof, including ultrasonic vibration.Other control elements64 may be directed to selecting or determining operational parameters, such as heat level and ultrasonic vibration. For instance, an operator may be given an opportunity to adjust the heat level to a lower temperature when the ultrasonic vibration feature is activated. In other cases, the heat level is automatically reduced upon activation of the ultrasonic vibration feature. More generally, an operator may adjust the temperature level to customize the curlingiron20 for personal use requirements or preferences.
• The positioning, structural configuration, and other physical characteristics of the electrical and circuit-related components of the curlingiron20 may also vary considerably from the example shown. For example, circuit elements may be disposed on more than one circuit board or otherwise spaced apart to improve heat dissipation. Details regarding the electrical characteristics of the circuit-related components are provided below.
• As described below, theultrasonic transducer36 is generally configured to generate ultrasonic vibrations to improve and facilitate hairstyling through lower levels of applied heat. In this example, theultrasonic transducer36 includes an assembly of components disposed within thebarrel26. In that way, the vibrations generated by thetransducer36 are transmitted through thebarrel26 to thestyling surface30, at which point the vibrations are, in turn, transmitted to the hair in contact therewith. To that end, theultrasonic transducer36 is generally disposed in a position that allows the vibrations to be transmitted to thestyling surface30 and, ultimately, to the hair being styled. In this example, thetransducer36 is mounted or oriented lengthwise along a longitudinal axis of thebarrel26. The longitudinal axes of thebarrel26 and thetransducer36 are aligned such that the ultrasonic vibrations are generated in a direction parallel to the longitudinal axis. This transducer orientation allows the size and length of thetransducer36 to be maximized in the limited space available within thebarrel26. However, as shown with the examples described below, the location and orientation of thetransducer36 may vary, including, for instance, non-axial orientation involving a radial mount.
• With reference now to aFIG. 2, a partial view of the curlingiron20 is shown to depict one possible location of the ultrasonic transducer in greater detail. In this example, theultrasonic transducer36 is disposed adjacent an end cap or plug66 of thebarrel26. Thetransducer36 is shown in phantom to depict how afront face68 of theultrasonic transducer36 is in contact with theend cap66. To this end, thetransducer36 is positioned at an outer ordistal end69 of thebarrel26 such that thefront face68 abuts theend cap66. As described further below, thetransducer36 is also positioned, shaped and sized for further contact with thebarrel26. Generally speaking, the width of thetransducer36 may result in contact with the longitudinal wall(s) of thebarrel26. In this case, thetransducer36 is configured such that an inner longitudinal wall of thebarrel26 is contacted by arim70 of thetransducer36 to form an annular interface at thefront face68. In this way, the vibrations generated by thetransducer36 may be transmitted to thestyling surface30 via both theend cap66 and the annular interface with thebarrel26. As also shown inFIG. 3, therim70 extends along the longitudinal axis of thetransducer36 to form a cylindrical surface or band for the annular interface with thebarrel26.
• Theultrasonic transducer36 may be disposed at other locations within theelongate housing22. For example, thetransducer36 may be disposed at theinner end50 of thebarrel26. In that case, thefront face68 of thetransducer36 may again be adjacent another end cap or other face (not shown) to maximize the surface area of the interface between thetransducer36 and thebarrel26. In such cases, thetransducer36 may not extend the entire width of thebarrel26 so as to allow electrical connections and other elements to pass by thetransducer36 to reach the heating elements34 (FIG. 1). To that end, therim70 may include a gap or spacing to act as a pass-through for wiring, etc. In other cases, the annual interface may be the sole transmission conduit for the ultrasonic vibrations. If thetransducer36 is disposed not at either end of thebarrel26, but rather at a point therebetween, the contact between therim70 and the inner surface of thebarrel26 may form the only transmission conduit between thebarrel26 and thetransducer36 for the ultrasonic vibrations. Still other cases may position thetransducer36 within thehandle24, at a wall or other element separating thehandle24 and thebarrel26, or at any other location within thehousing22.
• Theultrasonic transducer36 may be secured within theelongate housing22 via an adhesive layer orfilm72 between therim70 and the inner surface of the barrel26 (also shown inFIG. 4). A variety of adhesive materials are well suited for the mounting, including, for instance, those products commercially available from 3M Corporation, which may be applied to the inner surface(s) of thebarrel26. The 3M adhesive products may be configured as a pressure-sensitive film. The adhesive material is generally insensitive to the elevated heat levels within thebarrel26. The material from 3M Corporation is rated for use at up to 550 F degrees. Theadhesive layer72 generally addresses the challenge of securing thetransducer36 without dampening or otherwise interfering with the transmission of the ultrasonic vibrations. To that end, theadhesive layer72 may be configured and applied as a thin film. In some cases, theultrasonic transducer36 is alternatively or additionally inserted into thebarrel26 or, more generally, theelongate housing22 in a pressure-fit arrangement. In that way, the ultrasonic vibrations do not experience a significant barrier to transmission through the annular or other interface between thetransducer36 and thestyling surface30. Furthermore, an adhesive layer need not be applied between thetransducer36 and theend cap66, thereby allowing the vibrations to pass through that interface without adhesive-related dissipation.
• FIG. 3 shows theultrasonic transducer36 in greater detail. Thetransducer36 generally includes ahorn80, apiezoelectric section82, and areflector84. In this example, these stages of thetransducer36 are arranged in the Langevin configuration. Thehorn80 is generally configured as a front-end stage to transmit the ultrasonic vibrations generated in thepiezoelectric section82. To that end, thehorn80 is shaped and otherwise configured for efficient transfer and transmission of the vibrations. In this example, thehorn80 is shaped as a truncated cone (or frustum) such that a tapered section of increasing diameter extends forward from thepiezoelectric section82. Thehorn80 terminates in afront face86, which may be flat to maximize contact with theend cap66, the barrel26 (FIG. 1) or other component of thehousing22. Thereflector84 is positioned behind thepiezoelectric section82 as a back-end stage of thetransducer36 generally designed to reflect or direct the ultrasonic vibrations in the desired transmission direction through the front end stage (e.g., through thefront face86 of thehorn80 toward thebarrel26 or the housing22). Thereflector84 is sized and weighted to that end. For example, a solid cylinder of stainless steel or other dense material may be used as thereflector84. Thereflector84 is set at a distance that is a direct multiple of the wavelength of the vibrations so that wave reflections will be in phase with the waves emanating from thepiezoelectric section82.
• Thepiezoelectric section82 is disposed between the front- and back-end stages of thetransducer36. Thepiezoelectric section82 includes a set ofpiezoelectric discs88 arranged in a stack. Eachdisc88 may be made of Lead zirconate titanate (PZT) or other piezoelectric ceramic(s) or other material(s) with the piezoelectric property of changing shape upon the application of an electric field. PZT and other ceramic materials are useful in the curling iron context due to heat compatibility, as theheating elements34 are conventionally raised to temperature levels of approximately 400-450° F. for hairstyling (or 250-350° F. with the benefit of ultrasonic vibration as described herein). Thepiezoelectric discs88 as well as thetransducer36 are commercially available from Sunnytec Electronics Co. Ltd. (Taiwan). The disc stack is generally configured so that the vibrations generated by thediscs88 are in phase for constructive amplification. In this case, the stack includes fourdiscs88 oriented axially, or longitudinally, within the housing22 (FIG. 1). Other disc arrangements are possible, but an even number of discs is useful for maintaining a constructive interference scenario for the vibrations.Electrodes90 are positioned on each side of thediscs88 to apply an excitation or drive signal to eachdisc88. The excitation signal may include an AC component with, for instance, a 160 Volt peak-to-peak amplitude. The amplitude may be increased to amplify the strength of the resulting vibrations. Amplitudes as high as 320 V peak-to-peak have been found to be suitable. The number ofpiezoelectric discs88 may be increased to accommodate the higher amplitudes. Other characteristics of the excitation signal, including frequency, may be established through pulse density modulation. The frequency (or effective frequency) of the excitation signal generally determines the frequency of the vibrations generated by thetransducer36. As a result, the excitation signal frequency is generally selected in accordance with the desired vibration frequency of thetransducer36.
• Positive and negative pairs of theelectrodes90 are reached viaU-shaped contacts92, which generally run along the stack lengthwise before bending radially inward toward theelectrodes90. Eachcontact92, in turn, is connected to wiring (not shown) that leads to the circuit board32 (FIG. 1). Thecontacts92 may be integrally formed with theelectrodes90. More generally, eachcontact92 may be configured as a plate having a flat section. In some cases, the flat section of the plate may provide a stable surface for mounting thetransducer36 within the housing22 (FIG. 1).
• The three stages of thetransducer36 are secured to one another by a bolt orother fastener94 that extends axially forward from thereflector84 through thediscs88 of thepiezoelectric stage82 to reach thehorn80. To that end, eachdisc88 and eachelectrode90 may have a hole (not shown) formed in the center thereof to allow thebolt94 to pass through. Thebolt94 may have a threadedend96 configured to engage a matching threaded opening (not shown) in thehorn80. Thebolt94 may be welded or otherwise fixed to thereflector84 at its other end. In some cases, thebolt94 may be integrally formed with thereflector84. During assembly of thetransducer36, thereflector84 is rotated relative to thehorn80 for compression of the stages of thetransducer36. Thehorn80 and thereflector84 include opposed pairs of flattenedsections98,100, respectively, to allow a wrench or other tool to help tighten the assembly to reach a suitable level of compression.
• FIG. 4 shows the exemplary axial mounting of thetransducer36 within theouter end69 of thebarrel26 in greater detail. Thefront face68 of thehorn80 is disposed along, and in contact with, theend cap66 of thebarrel26. Therim70 is sized so that the annular interface and contact between thetransducer36 and thebarrel26 spans the entire circumference of aninner surface102 of thebarrel26. In this case, theadhesive layer72 is, in fact, limited to the annular interface such that the vibrations passing through the front face/end cap interface avoid any dampening or suppression that would otherwise arise from the presence of an intermediate adhesive layer. Theadhesive layer72 may also be used to secure theend cap66 in place at theouter end69 of thebarrel26. Additional mounting hardware (not shown) may be disposed within thebarrel26 to hold thetransducer36 in place.
• Theheating elements34 in this example are disposed along theinner surface102 of thebarrel26. However, theheating elements34 need not be curved to match the curvature of thebarrel26 and, thus, need not be disposed in contact with theinner surface102 across their entire width or length. Instead, theheating elements34 are more generally disposed along thebarrel26 at a radial position outward of thetransducer36 and either directly or indirectly coupled to theinner surface102. An indirect coupling may include heat-conductive mounting hardware (not shown) that establishes the transmission of heat from theelements34 to theinner surface102 and, from there, through thebarrel26 to thestyling surface30 opposite theinner surface102.
• Thetransducer36 has an overall axial length L_Tand a horn length L_H, as defined inFIG. 4. Generally speaking, these length dimensions are selected to maximize the generation and transmission of ultrasonic vibrations through resonance of thetransducer36. To that end, the dimensions L_Tand L_Hmay be about λ/2 and λ/4, respectively, where λ is the wavelength of the ultrasonic vibrations generated by thetransducer36. When these length conditions are met (or approximately met), thetransducer36 may be driven to an oscillation mode having a node (where vibration amplitudes are at or near a minimum) at arear face104 of thereflector84 and an anti-node (where vibration amplitudes are at or near a maximum) at thefront face68 of thehorn80. Under these conditions, the vibrations generated by thetransducer36 form standing waves within thetransducer36, effectively reflecting from the back-stage reflector84 and combining in phase with those traveling forward to thehorn80 to reach thefront face68 at peak strength. In one example, the overall axial length L_Tis 56 mm and the horn length L_His 17 mm.
• Notwithstanding the foregoing, the diameter of thebarrel26 may present challenges for the design and mounting of thetransducer36 and thereby cause a deviation from the ideal λ/4 configuration. In some cases, the diameter of therim70 of thehorn80 may be limited by the diameter of thebarrel26. As a result, the length of thehorn80 may be shorter than the optimal length in order to achieve resonant operation with the other stages of thetransducer36. In one example with a 1.5″ diameter barrel, thehorn80 is shorter than the optimal length to ensure that thehorn80 resonates at the same frequency as the piezoelectric stage. The shorter horn length also helps to maintain a proper mass differential between the reflector and horn stages in the interest of ensuring that the vibrations are directed toward the horn.
• With the horn-shaped (or frustoconical) transducer configuration shown inFIGS. 1-4, the lengths may be selected for operation at a number of natural resonant frequencies between about 20 kHz and about 1 MHz. In some cases, thepiezoelectric discs88 may be configured such that the operating (i.e., vibration) frequency exceeds about 50 kHz. The vibration frequency for one exemplary embodiment involving the horn-shaped transducer configuration was above about 60 kHz and, in some cases, about 87.5 kHz. The vibration frequency may be selected in accordance with other operational parameters, including power consumption, temperature level, weight, and size. Differences in barrel geometry and size may result in different resonant frequencies. Thus, the foregoing operational frequencies are exemplary in nature due to the exemplary nature of thetransducer assembly36, which has a front face diameter of 29.5 mm, a disc/reflector diameter 15.04 mm, and a reflector length of 25.44 mm.
• During operation, the vibrations generated by thepiezoelectric discs88 travel axially forward to thehorn80. Once at thehorn80, the vibrations travel further forward to transmit energy to theend cap66 via thefront face68. The vibrations of thehorn80 also spread radially to transfer energy to thebarrel26 via the annular interface between therim70 and theinner surface102 of the barrel. Through these transmission paths, the ultrasonic energy eventually reaches the hair clamped between thestyling surface30 and the styling surface44 (FIG. 1). There, the ultrasonic energy is applied to the moisture entrapped in the medulla of the hair.
• The transmission of ultrasonic energy improves the styling of the hair by facilitating heat transfer within thebarrel26 and by accelerating the restructuring of hydrogen bonds with the hair. On the one hand, the ultrasonic vibrations result in more efficient transfer of heat from theheating elements34 to the hair through excitation of the molecules within thebarrel26. The excitation of the barrel molecules lowers the heat transfer resistance of thebarrel26. More effective transmission of heat through thebarrel26 lowers the possibility of undesirable hot spots along the barrel, which could otherwise damage hair. More effective heat transmission also lowers the overall heating required to raise the temperature of areas along thebarrel26 other than the hot spots. The general result is more uniform distribution of heat along thebarrel26. Turning to the effects on the hair itself, the vibrations apply energy to the hydrogen bonds between the water molecules in the medulla of the hair. To style hair, these weak electrochemical bonds are broken so that the molecular bonds can be reformed with the molecules in different positions. The ultrasonic energy supplies part of the total amount of energy required to break the bonds. As a consequence, less energy is required from the heat, which ultimately helps to prevent damage to the hair follicle resulting from the heat. For all of these reasons, the hair can be styled faster, which, in turn, lowers the total amount of heat applied to the hair, thereby reducing the possibility for damage.
• With reference now toFIG. 5, an exemplary drive circuit110 for the ultrasonic transducer36 (FIGS. 1-4) includes several components for controlling and generating the drive signal. The circuit110 as shown does not include any components for controlling or powering the heating elements34 (FIGS. 1 and 4). However, the drive and heating control circuitry may be integrated to any desired extent. For example, the input control parameters for activation/deactivation, heating levels (e.g., low, medium and high), and ultrasonic operation may be delivered to both the drive and heating control circuitry for integrated operation. The circuit110 includes anEMI line filter112, which is optional depending on whether interference on the AC power line provided to the curlingiron20 is considered a problem. In some cases, such interference or other noise may affect the operation of the circuit110 to an extent that the drive signal includes harmonic or other undesired frequency components. The operation of the curlingiron20 may, as a result, become less efficient (e.g., through diversion of power away from the effective frequencies). Alternatively or additionally, the presence of undesired components in the drive signal may lead to vibration at undesired frequencies, such as audible frequencies. In this example, the filtered AC line power is provided to a high voltage AC-to-DC converter114 and a low voltage AC-to-DC converter116. Thehigh voltage converter114 includes abridge rectifier118 and capacitor C3 configured to generate a high DC voltage input V_hv suitable for use in generating the drive signal. Thelow voltage converter116 includes abridge rectifier120 and avoltage regulating network122 to generate an output suitable for use as a power supply Vcc for the logic devices of the circuit110. In this case, thenetwork122 includes a Zener diode D3 to lower the output of thebridge rectifier120 and aregulator124 to generate a stable power supply voltage Vcc of 12 Volts. Theregulator124 may include one of the linear regulators commercially available from National Semiconductor Corporation associated with product number LM78L12.
• The exemplary drive circuit110 is configured as a full H-bridge driver circuit. Other control circuits may instead include other self-oscillating, switched power supplies, such as a half bridge driver circuit. Still other alternatives may be based on a driven circuit configuration in which, for instance, a crystal is used to set an operating frequency. In this case, the power supply voltage Vcc is provided to atimer126 configured and set in astable mode for use as an oscillator. To that end, thetimer126 is coupled to a resistor R12 to set the frequency and duty cycle parameters. A commercially available timer suitable for use as thetimer126 may be obtained from National Semiconductor Corporation associated with product number LM555. The oscillating output of thetimer126 may be provided to adivider128 configured to, for instance, reduce the duty cycle by 50%. A full-bridge driver130 receives the oscillating signal to develop switch control signals for two full-bridge switch circuit pairs132. In operation, the switch circuit pairs132 are selectively activated in accordance with the switch control signals to generate an AC output drive signal based on the high DC voltage input V_hv and apply the signal to the ultrasonic transducer (FIGS. 1-4) to drive thetransducer36 for generation of the ultrasonic vibrations.
• One or more of the above-identified integrated circuit chips or circuit components may be coupled to a heat sink. The heat sink(s) help maintain the operating temperatures of the chips and components to levels within a desired operating temperature range. The heat generated by the heating elements34 (FIG. 1) as well as the heat generated by the operation of the drive circuit110 itself may lead to temperatures within the housing22 (FIG. 1) that would otherwise be elevated to undesirable levels. That said, the operation of the oscillator and other AC-related components of the circuit110 has been found to remain functional despite the heat levels reached during operation. For instance, the operating temperatures may result in a slight shift in the frequency of the drive signal. In some cases, the frequency shift may be inconsequential, while in other cases other parameters can be adjusted to compensate for the shift.
• In some cases, one or more circuit elements may be incorporated into the drive circuit110 to address spurious vibration modes or other undesired vibrations. For example, a potentiometer may be added to prevent undesirable harmonic frequencies of the drive signal frequency from reaching the transducer. Otherwise, the harmonic frequencies may be audible to the operator of the curling iron or the operator's pets. The potentiometer may be configured to modify the duty cycle of the oscillator output.
• The drive signal generated by the circuit110 may have a peak-to-peak amplitude of about 160 Volts. With the full H-bridge driver is used, the amplitude may be increased to as high as 320 Volts, in which case the number of piezoelectric discs may be increased accordingly to accommodate the higher amplitude. Thus, the amplitude may fall within the range of about 160 Volts to about 320 Volts for some embodiments. With these amplitudes, the drive signal may, for instance, provide 10-100 Watts of power to the ultrasonic transducer. The amplitudes may exceed that range in some cases (e.g., transformer-based circuits) to deliver more energy to the hair and the barrel, although at the cost of increased component size and weight.
• The drive circuit110 does not include a transformer to generate the high AC drive voltage, despite the prevalence of transformers in ultrasonic drive circuits. A transformer would add significant and undesirable amounts of size and weight to the hairstyling device. While the non-transformer drive circuit described above may be limited to lower drive voltage amplitudes, that factor can be offset by the selection of the drive frequency and optimal tuning of the transducer horn. For example, the transducer geometry may be adjusted and analyzed to operate at a natural resonant frequency of the transducer. An FEA package was used to analyze and determine the natural resonant frequencies. Geometric adjustments then led to an operational frequency close to the natural resonant frequency of the transducer and the drive frequency of the piezoelectric discs. The mounting of the transducer may also lead to improved transfer of the axial horn vibrations to the barrel. Notwithstanding the foregoing, all component values shown inFIG. 5 are exemplary in nature in multiple respects, including, for instance, that the component values are directed to generating a drive signal with a frequency of 40 kHz.
• Turning toFIG. 6, the benefits of ultrasonic vibration are now described in connection with another exemplary hairstyling device. Like the curlingiron20 described above, aflat iron140 is configured to transmit ultrasonic energy to the hair being styled via one or more styling surfaces. In this case, the styling surface(s) are flat for hair straightening rather than curved for hair curling. Differences relating to ultrasonic vibration between the hairstyling devices are driven by the device geometries. For example, some of the differences relate to the direction in which the vibrations propagate. With flat and other non-circular device geometries, the vibrations may travel laterally, longitudinally, or any combination thereof. These and other differences and similarities are described further below.
• Theflat iron140 includes an elongate housing142 that has several components in common with thehousing22 described above. The housing142 similarly defines ahandle grip surface144 and astyling surface146 spaced from thehandle grip surface144. Aplate148 is also pivotally coupled to the housing142 to clamp the hair between astyling surface149 of theplate148 and thestyling surface146. In this case, however, theplate148 is carried by another elongate housing150 (rather than a clip), and thestyling surface146 is an exterior face of anotherplate152 carried by the housing142. Thehousing150 is configured as a pivoting arm (or wand) with a proximal, linked end154 upon which a pivot joint156 is mounted for coupling with a proximal, linkedend158 of the pivoting arm (or wand) of the housing142. The two wands or arms extend outward from the linked ends to define a longitudinal axis of eachhousing142,150. Theplates148 and152 are disposed at distal, free ends160 and162 of the housing arms, respectively, at locations disposing the styling surfaces146,149 opposite one another. Thehousing150 also has ahandle grip surface164 so that an operator can grasp the two wand-shapedhousings142,150 to bring the styling surfaces146,149 toward one another. In this manner, theplates148,152 can act as pressure plates to apply pressure to the hair to be styled therebetween. The pivot joint156 is spring-loaded to bias theflat iron140 open when no inward force is applied to the handle grip surfaces144,164.
• Eachplate148,152 may be fixedly or otherwise mounted within a recess, notch, or other hole in its respective housing. The plates may be made from stainless steel, aluminum, copper, or any other suitably thermal conductive material. Eachhousing142,150 may be made from stainless steel, aluminum, plastic, or any other desired material.
• Theflat iron140 also includes apower cord166 for delivery of power to one or more control circuits (not shown) disposed within one or both of thehousings142,150. In this case, a control circuit may be disposed within the housing142 in proximity to a control panel168 that includesuser interface elements170,172 for operator control of theflat iron140. The control panel168 may be used to activate and deactivate an ultrasonic vibration feature of theflat iron140 provided by anultrasonic transducer174. The control panel168 may also be used to select a temperature level or other operational parameters. Heat is applied to the hair clamped between the styling surfaces146,149 via one ormore heating elements176 in thermal communication with a respective one of thesurfaces146,149. Eachheating element176 may be configured as a flat plate secured to an interior side of one of theplates148,152. In this case, the housing142 is shown with one of theheating elements176, although, in other cases, theother housing150 may contain the sole (or an additional) heating element secured to theplate148.
• Theultrasonic transducer174 is again configured as an assembly of sections or stages disposed within a hollow interior space of a wand or arm of the hairstyling device. Thetransducer174 is generally configured to generate ultrasonic vibrations to facilitate energy transmission with one or both of thepressure plates148,152 and to transfer vibration energy to the hair clamped therebetween. However, in this case, the interior space provided by eachhousing142,150 of theflat iron140 may not be sufficiently large or appropriately shaped to mount the Langevin transducer described above in a manner that disposes the front face of the horn in contact with a matching surface within the housing. However, it may remain beneficial to orient thetransducer174 axially within the housing, with the longitudinal axes of thetransducer174 and the housing aligned. Consequently, thetransducer174 in the depicted example is configured with ahorn178 having an adapter that translates the longitudinal, axial vibration into vibration in a lateral direction toward one of theplate152. To that end, thehorn178 includes an L- or elbow-shapedhead180 that projects forward from a cylindrical section of thehorn178 adjacent apiezoelectric stage182. After extending forward, the L-shapedhead180 projects laterally downward to place anouter end183 in contact with an interior surface184 of theplate152. The remainder of thetransducer174 may rest upon, and be secured to theheating element176 or other surface or component within the housing142. A similarly mounted transducer may be housed within thehousing150 for transmission of ultrasonic vibrations through theplate148. In operation, the vibration mode causes thehead180 to move laterally (as opposed to axially) toward and away from theplate152. Thetransducer174 thus vibrates along a hammer-like motion path.
• Despite the directional translation of the vibration propagation achieved by thehead180, the profile of the flat iron wands or arms may, in some cases, be too thin to mount thetransducer174 within the housing. The thickness of theheating element176 may also be a factor. Part of the problem may also arise from a transducer selected or configured for a desired resonant frequency, power capacity, or other operational parameter that ends up being too large for the housing.
• FIG. 7 depicts one optional solution in which a flat iron wand orarm190 has amain housing192 and atransducer cover194. Themain housing192 may be configured in a similar manner to those described above, with the exception of a hole on an outward facingside196 from which thetransducer cover194 flares or extends laterally outward. In this way, thetransducer cover194 defines a secondary housing or enclosure that provides additional space for an interior transducer mount. The transducer (not shown) may have a configuration like any of the transducers described herein, including the Langevin configuration shown inFIG. 3. Thus, the transducer may be mounted in longitudinal alignment as described above, with or without the adapter translation that allows the transducer to meet the interior surface of aplate198. However, with sufficient additional space under thecover194, the transducer may be mounted laterally with the front face of an adapter-free Langevin horn in contact with the interior surface of theplate198, such that the longitudinal axis of the transducer is orthogonal to the longitudinal axis of themain housing192. Thus, themain housing192 and thetransducer cover194 may be shaped as desired and, furthermore, be integrally formed to any desired extent, including, for instance, as a unitary molded component.
• With reference now toFIGS. 8 and 9, aLangevin transducer200 with a vibration-translatinghorn adapter202 is shown in greater detail. Starting from a back end, thetransducer200 has areflector stage204 in compression fit with apiezoelectric stage206 and ahorn stage208. The reflector andpiezoelectric stages204,206 may be configured in a manner similar to the example described above. Thehorn stage208 may have acylindrical section210 having aninner end212 adjacent thepiezoelectric stage206 and anouter end214 adjacent thehorn adapter202. Theouter end214 may have a flat face from which an axially orientedarm216 of thehorn adapter202 extends forward. Thearm216 may be integrally formed with thecylindrical section210 to any desired extent or, alternatively, be attached to thecylindrical section210 via a variety of different attachment techniques (e.g., welding, adhesive, etc.). Thearm216 projects outward until reaching a corner orshoulder218 of theadapter202, at which point anotherarm220 projects laterally downward. Thearms216,220 need not be rectilinear as shown, and may be solid, hollow, or any combination thereof.
• As shown inFIG. 9, a bottom or downward facingsurface222 of thearm220 is disposed in contact with aninner face224 of astyling plate226. Theface224 is exposed for such contact between aheating element227 and aninward face228 of ahousing230. Thehorn adapter202 may be secured to theinner face224 via an adhesive layer or film. Alternatively or additionally, theadapter202 may be fixed to theplate226 via welding or other attachment techniques. In some cases, thehorn adapter202 is fixed in place by mounting hardware that engages thehousing230 or theheating element227. For example, the mounting hardware may engageelectrode plates232 of thepiezoelectric stage206. Theadapter202 may be optionally attached to an inner surface of theheating element227 or other component or surface within thehousing228.
• The overall length L_Tand horn length L_Hdimensions of thetransducer200 may be selected in accordance with the above-described considerations. The horn length includes the combined length of thecylindrical section210 and theadapter202. The length of thereflector stage204 is noted as L_Rand may be a direct multiple of the wavelength in the interest of constructive interference (as is the case with the above-described example).
• As described above, thetransducer200 may be configured with dimensions offset from the desired lengths in order to ensure that the horn resonates at substantially the same frequency as the ceramic discs of the piezoelectric stage. As a result, the piezoelectric discs are driven with a frequency corresponding with the resonant frequency of the transducer. Thus, the horn length is shorter than λ/4. One exemplary transducer has a main body length of 56 mm, a horn length of 28 mm, a disc diameter of 15.04 mm, a cylindrical horn section diameter of 16.25 mm, an adapter (hammer) width of 12 mm, and an adapter (hammer) lateral extension width (or height) of 15 mm.
• Operation of the transducer configuration shown inFIGS. 8 and 9 has been shown to provide a number of optional resonance points between about 20 kHz and about 1 MHz that may be selected as the operating frequency. The transducer has effectively transmitted ultrasonic energy at about 67.5 kHz, about 75 kHz, and about 77.5 kHz.
• With reference now toFIG. 10, adrive circuit240 is configured for controlling the transducer ofFIGS. 8 and 9. Thedrive circuit240 has several features in common with the drive circuit described above and may, in fact, be used to control the other transducers described herein. Thedrive circuit240 is also generally configured as a full H-bridge driver, albeit with different circuit elements. For instance, thecircuit240 includes abridge rectifier242 to develop the high DC voltage from which the drive signal is generated. An output of the bridge rectifier is also delivered to an AC-to-DC converter244 for generation of a 15 Volt power supply, which, in turn, is fed to aregulator246 that develops a 5 Volt power supply used by anoscillator248 and aninverter250. Theoscillator248 establishes the frequency of the drive signal by passing its oscillating output to a pair of full-bridge drivers252, either directly or indirectly through theinverter250. Eachdriver252 then sends switch control signals in accordance with the oscillator frequency to a pair ofswitch circuits254, the terminals of which are connected across the transducer discs in the full H-bridge configuration.
• FIGS. 11A and 11B graphically depict the results of experiments that show the increases in energy transmission arising from the application of ultrasonic vibrations. With a curling iron configured as described above in connection withFIG. 1, the power transmission increased about 14% when the ultrasonic vibrations were applied. With the flat iron ofFIG. 6, the power transmission increased at least about 10%. The increases were measured via a determination of the amount of energy transferred to a wet cloth. Specifically, the barrel (or flat plate) was heated to its maximum temperature setting with the ultrasonic transducer both turned on and turned off. In each case, a wet cloth with a known weight was applied to the barrel (or plate), and the iron was allowed to heat the cloth for five minutes. The cloth was then weighed to determine how much water has been removed. From that determination, the amount of energy transferred to the cloth was calculated. The same curling (or flat) iron was used in each case so that thermal masses, maximum temperatures, and other iron variables remained constant.
• FIG. 12 shows anultrasonic curling iron260 constructed in accordance with another exemplary embodiment. The curlingiron260 may be similar to the curling iron described above with the exception of the transducer and heating element locations. In this case, anultrasonic transducer262 is disposed outside of abarrel264. Even though thetransducer262 is not housed within thebarrel264, thetransducer262 is again disposed and oriented along the longitudinal axis of thebarrel264. Thetransducer262 is secured to anexterior side266 of anend cap268 of thebarrel264 in any desired manner. As described above, thetransducer262 may have a horn with a flat front face to maximize the surface area in contact with theexterior side266 of theend cap268. Thetransducer262 may be housed within anenclosure270 coupled to thebarrel264 via one or more fasteners, an adhesive layer, or any other attachment mechanism. This alternative location for thetransducer262 may provide design flexibility if, in fact, space within thebarrel264 is too limited for a desired transducer configuration, size, geometry, etc. Thetransducer262 is shown schematically inFIG. 12, and need not have the Langevin transducer configuration shown. Despite the alternative transducer location, the vibration transmission path still passes through astyling surface272 of thebarrel264.
• One advantage of this exterior mounting of the embodiment ofFIG. 12 is that the heating element(s) may run the entire length of thebarrel264. With thetransducer262 not disposed within thebarrel264, thetransducer262 does not block the extension of the heating elements. As a result, the heating elements (or one end thereof) may be disposed at or near adistal end274 of the barrel.
• FIG. 13 depicts another alternative Langevin-based transducer configuration that does not rely on a lateral translation of the vibrations via a horn adapter. In this example, atransducer280 includes a substantiallyfrustoconical horn stage282 extending forward from piezoelectric and reflector stages284,286. Thehorn stage282 is generally shaped so that a contact interface with aplate288 disposed along thehorn stage282 is formed. To that end, thehorn stage282 includes a pair of diametrically opposedflat surfaces290, each of which may have a parabolic outline. Thesurfaces290 may lie in parallel planes such that, when thetransducer280 is oriented axially along theplate288, one of thesurfaces290 lies flat against a top side of theplate288 to increase the contact surface area. To that end, anopening292 in aheating element294 may provide access to the top side of theplate288. In other cases, theopening292 may be cut out to match the shape of the transducer surface.
• Generally speaking, the material(s) from which the transducer horns described above are made are selected to ensure effective transmission of the ultrasonic vibrations through the interface between the horn and the barrel, plate, or other component. Effective transmission generally avoids reflection at the interface, which may occur in situations where the impedance of the materials on either side of the interface do not sufficiently match. Suitable materials for the transmission of ultrasonic vibrations in the context of hairstyling devices include aluminum and duraluminum because the acoustic impedance of these materials is approximately halfway between (i.e., an average of) the acoustic impedances of the ceramic (PZT) discs (45 MRay) and the water in the hair being styled (1.5 MRay), i.e., the final medium. Aluminum and duraluminum, for instance, have acoustic impedances of 17.3 MRay and 17.6 MRay, respectively. Duraluminum may be preferable over aluminum because it is harder. Other materials may be used, including those that have crystalline or polycrystalline material structures.
• Notwithstanding the advantages of the foregoing examples, the transducer may be mounted in a variety of locations on the hairstyling devices. For instance, the transducer may be mounted on the clip or clamp of a curling iron. The transducers also need not be oriented axially, i.e., along the longitudinal axis of barrel. Even when the transducer is oriented axially, the horn may be configured to transmit vibrations in a direction transverse to the longitudinal axis of the barrel. Thus, the vibrations may be transmitted through the barrel, plate, or other housing structure radially, longitudinally, laterally, or any combination thereof. A variety of other translation sections other than the elbow-shaped adapter described above may be used to change the direction of the vibrations. Each housing or styling surface may contain or have more than one transducer associated therewith.
• The transducers may be mounted on a flat surface extruded onto the inner surface of the above-described barrels or wands. The flat surface may be similar to those formed for supporting heating elements. The transducers may alternatively or additionally mounted to an end of the plates described above for transmission of the vibration longitudinally.
• The plate with which the transducer is contact in some of the above-described embodiments may be floating relative to the wand or arm housing via one or more springs. The plate is indirectly coupled to the wand housing via the spring(s), in contrast to the plates described above which are rigidly fixed to the wand housing. The separation or indirect coupling of the plate and the wand housing may reduce the amount of vibration energy absorbed by, or dissipated via, the housing.
• The above-described barrels, plates and other objects with which the transducers are in contact may be sized to maximize wave transmission within the plate or object. For instance, the plate or barrel may have a length or other dimension equal to the wavelength or a direct multiple thereof.
• Other ultrasonic generators may be used. As described above, the device responsible for generating the ultrasonic vibrations may be located at various positions, including those within the barrel, handle, arm, wand, or other hollow structure or housing, as well as those exterior to, but in contact with, such structures, as well as those in contact with some other element in contact with the hair, such as a clip or clamp. Thus, in some cases, the ultrasonic generator is not in direct contact with the barrel or other iron structure.
• The construction and configuration of the wands, arms, and elongate housings of the devices described above may vary widely from the examples shown. They need not be of uniform construction, circumference, diameter, or two-piece construction
• The disclosed hairstyling devices are not limited to curling irons with clips or spring-loaded clamps. The ultrasonic vibrations may be applied to the hair via clipless wands in which the hair is wrapped around a rod or styled using an iron with a Marcel handle.
• A variety of horn shapes may be used with the disclosed hairstyling devices. The transducer horns are not limited to cylindrical or frustoconical shapes. In this way, the disclosed hairstyling devices may accommodate a wide range of barrel diameters and shapes. The disclosed hairstyling devices are also not limited to Langevin transducers or bolt-clamped transducer stacks. A variety of different piezoelectric arrangements may be used, such that the configuration and construction of the sections, stages, or components may vary from the examples shown above.
• Although certain curling irons and flat irons have been described herein in accordance with the teachings of the present disclosure, the scope of coverage of this disclosure is not limited thereto. On the contrary, all embodiments of the teachings of the disclosure that fairly fall within the scope of permissible equivalents are disclosed by implication herein.

Claims (17)

1. A device for styling hair comprising:

a handle;

a barrel extending from the handle and having a styling surface spaced from the handle, the styling surface being configured for winding the hair around the barrel;

a heating element in thermal communication with the barrel to transfer heat to the hair via the styling surface of the barrel; and

an ultrasonic transducer configured to generate ultrasonic vibrations, wherein the ultrasonic transducer is disposed within the barrel to transmit the ultrasonic vibrations to the hair via the styling surface of the barrel.

2. The device ofclaim 1, wherein the handle and the barrel are oriented along a longitudinal axis, and wherein the ultrasonic transducer is oriented along the longitudinal axis such that the ultrasonic vibrations are generated in a direction parallel to the longitudinal axis.

3. The device ofclaim 2, wherein the ultrasonic transducer includes a horn with a rim in contact with an interior surface of the barrel that defines an annular interface through which the ultrasonic vibrations travel.

4. The device ofclaim 1, wherein the ultrasonic transducer includes a horn in contact with the barrel.

5. The device ofclaim 1, wherein the barrel terminates at an end cap, and wherein the ultrasonic transducer includes a horn in contact with the end cap.

6. The device ofclaim 1, wherein the barrel has a length equal to a wavelength of the ultrasonic vibrations or a multiple of the wavelength.

7. A device for styling hair comprising:

an elongate housing defining a handle grip surface and a styling surface spaced from the handle grip surface;

a plate pivotally coupled to the elongate housing to clamp the hair between the plate and the styling surface;

a heating element in thermal communication with the styling surface or the plate to transfer heat to the hair; and

an ultrasonic transducer configured to generate ultrasonic vibrations, wherein the ultrasonic transducer is disposed within the elongate housing to transmit the ultrasonic vibrations to the hair via the styling surface.

8. The device ofclaim 7, wherein the elongate housing is oriented along a longitudinal axis, and wherein the ultrasonic transducer is oriented along the longitudinal axis such that the ultrasonic vibrations are generated in a direction parallel to the longitudinal axis.

9. The device ofclaim 8, wherein the ultrasonic transducer includes a horn with a rim in contact with an interior surface of the elongate housing that defines an annular interface through which the ultrasonic vibrations travel.

10. The device ofclaim 7, wherein the ultrasonic transducer includes a horn in contact with the elongate housing.

11. The device ofclaim 7, wherein the elongate housing includes a barrel that terminates at an end cap, wherein the plate is curved to match a curvature of the barrel, and wherein the ultrasonic transducer includes a horn in contact with the end cap.

12. The device ofclaim 11, wherein the barrel has a length equal to a wavelength of the ultrasonic vibrations or a multiple of the wavelength.

13. The device ofclaim 7, further comprising a wand pivotally coupled to the housing, wherein the plate is mounted on the wand, and wherein the plate and the styling surface are flat.

14. The device ofclaim 7, further comprising a flat plate mounted on the elongate housing, the flat plate having a first side that defines the styling surface and a second side in contact with the ultrasonic transducer.

15. The device ofclaim 14, wherein the ultrasonic transducer is oriented in alignment with the elongate housing, and wherein the ultrasonic transducer includes a horn adapter to direct the ultrasonic vibrations laterally toward the flat plate.

16. The device ofclaim 14, wherein the flat plate has a length equal to a wavelength of the ultrasonic vibrations or a multiple of the wavelength.

17. The device ofclaim 7, wherein the elongate housing includes a handle that defines the handle grip surface and further includes a barrel extending from the handle and defining the styling surface.

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